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In JoVE (1)
- Using a Fluorescent PCR-capillary Gel Electrophoresis Technique to Genotype CRISPR/Cas9-mediated Knockout Mutants in a High-throughput Format
Other Publications (171)
- Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi
- Molecular & Cellular Proteomics : MCP
- Cancer Research
- Clinical Cancer Research : an Official Journal of the American Association for Cancer Research
- The Journal of Biological Chemistry
- Biophysical Chemistry
- The Journal of Biological Chemistry
- Biophysical Chemistry
- Proceedings of the National Academy of Sciences of the United States of America
- Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi
- Langmuir : the ACS Journal of Surfaces and Colloids
- Cell Cycle (Georgetown, Tex.)
- Annals of the New York Academy of Sciences
- Langmuir : the ACS Journal of Surfaces and Colloids
- The American Journal of Chinese Medicine
- Methods in Molecular Biology (Clifton, N.J.)
- Biosensors & Bioelectronics
- Chemical Communications (Cambridge, England)
- Physiologia Plantarum
- Biosensors & Bioelectronics
- Biosensors & Bioelectronics
- Biosensors & Bioelectronics
- Biosensors & Bioelectronics
- The Analyst
- Biosensors & Bioelectronics
- Analytical Chemistry
- Biosensors & Bioelectronics
- Molecular Vision
- Chemical Communications (Cambridge, England)
- The Analyst
- Biosensors & Bioelectronics
- Biosensors & Bioelectronics
- Zhonghua Xin Xue Guan Bing Za Zhi
- Biosensors & Bioelectronics
- Langmuir : the ACS Journal of Surfaces and Colloids
- Journal of Epidemiology
- Organic Letters
- Journal of Cell Science
- Biosensors & Bioelectronics
- [Zhonghua Yan Ke Za Zhi] Chinese Journal of Ophthalmology
- PloS One
- Molecular Vision
- Mediators of Inflammation
- Journal of Occupational Health
- Scandinavian Journal of Public Health
- The American Journal of Emergency Medicine
- Biosensors & Bioelectronics
- Zhongguo Fei Ai Za Zhi = Chinese Journal of Lung Cancer
- Bioscience Reports
- Molecular Vision
- Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu
- Molecules (Basel, Switzerland)
- Small (Weinheim an Der Bergstrasse, Germany)
- Molecular BioSystems
- Zhongguo Zhong Yao Za Zhi = Zhongguo Zhongyao Zazhi = China Journal of Chinese Materia Medica
- Xenobiotica; the Fate of Foreign Compounds in Biological Systems
- European Journal of Dermatology : EJD
- Molecular Medicine Reports
- Small (Weinheim an Der Bergstrasse, Germany)
- Vascular Cell
- International Journal of Molecular Sciences
- Lung Cancer (Amsterdam, Netherlands)
- ANZ Journal of Surgery
- PLoS Genetics
- Journal of Assisted Reproduction and Genetics
- Evidence-based Complementary and Alternative Medicine : ECAM
- Journal of Occupational Health
- BMC Medical Genomics
- Zhong Xi Yi Jie He Xue Bao = Journal of Chinese Integrative Medicine
- Nature Cell Biology
- Annual Review of Pathology
- Chemical Communications (Cambridge, England)
- Molecular Carcinogenesis
- Molecular BioSystems
- Nanomedicine : Nanotechnology, Biology, and Medicine
- Molecular Cancer Research : MCR
- Frontiers of Medicine
- Clinical Cancer Research : an Official Journal of the American Association for Cancer Research
- Angewandte Chemie (International Ed. in English)
- International Journal of Health Services : Planning, Administration, Evaluation
- Journal of Immunology (Baltimore, Md. : 1950)
- Applied Optics
- Zhonghua Zhong Liu Za Zhi [Chinese Journal of Oncology]
- Social Psychiatry and Psychiatric Epidemiology
- Molecular and Cellular Biology
- ACS Nano
- Journal of Nanobiotechnology
- Stem Cell Reports
- Pathology Oncology Research : POR
- Applied Optics
- Nature Genetics
- Scientific Reports
- Free Radical Biology & Medicine
- PloS One
- Cancer Cytopathology
- Journal of Pharmaceutical Sciences
- Cancer Research
- Clinical Cancer Research : an Official Journal of the American Association for Cancer Research
- Toxicology and Applied Pharmacology
- PloS One
- Drug Design, Development and Therapy
- Beilstein Journal of Nanotechnology
- Beilstein Journal of Nanotechnology
- Zhonghua Yi Shi Za Zhi (Beijing, China : 1980)
- Molecular Carcinogenesis
- Methods (San Diego, Calif.)
- Molecular Neurobiology
- Biochimica Et Biophysica Acta
- Biology of Blood and Marrow Transplantation : Journal of the American Society for Blood and Marrow Transplantation
- International Journal of Cardiology
- International Archives of Occupational and Environmental Health
- Tumour Biology : the Journal of the International Society for Oncodevelopmental Biology and Medicine
- FEBS Letters
- The Journal of Clinical Investigation
- Plant Physiology
- Drug Metabolism and Disposition: the Biological Fate of Chemicals
- Nanomedicine : Nanotechnology, Biology, and Medicine
- Health Affairs (Project Hope)
- International Journal of Clinical and Experimental Medicine
- Journal of Medicinal Chemistry
- Nature Chemistry
- Cancer Biomarkers : Section A of Disease Markers
- Scientific Reports
- PloS One
- Journal of Occupational and Environmental Medicine
- Scientific Reports
- International Journal of Clinical and Experimental Pathology
- The International Journal of Biochemistry & Cell Biology
- Small (Weinheim an Der Bergstrasse, Germany)
- Cancer Letters
- Stem Cells (Dayton, Ohio)
- European Journal of Pharmacology
- Molecular BioSystems
- Small (Weinheim an Der Bergstrasse, Germany)
- Scientific Reports
- The Journal of Clinical Investigation
- Nature Communications
- Scientific Reports
- Chemical Communications (Cambridge, England)
- Clinical Cancer Research : an Official Journal of the American Association for Cancer Research
- Cell Death & Disease
- Molecular BioSystems
- Accounts of Chemical Research
- ACS Applied Materials & Interfaces
- Journal of the American Chemical Society
Articles by Shang Li in JoVE
Using a Fluorescent PCR-capillary Gel Electrophoresis Technique to Genotype CRISPR/Cas9-mediated Knockout Mutants in a High-throughput Format
Muhammad Khairul Ramlee1, Jing Wang1, Alice M. S. Cheung1, Shang Li1
1Cancer & Stem Cell Biology Programme, Duke-NUS Medical School
Other articles by Shang Li on PubMed
[Effects of Three Different Iodine Interventions on the Speed of Normalization of Enlarged Thyroid Gland Due to Iodine Deficiency]
Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi. Aug, 2002 | Pubmed ID: 12411067
To compare the effects of three different iodine interventions on the speed of normalization of enlarged thyroid gland.
Proteomic Analysis of Oxidative Stress-resistant Cells: a Specific Role for Aldose Reductase Overexpression in Cytoprotection
Molecular & Cellular Proteomics : MCP. Feb, 2004 | Pubmed ID: 14676331
We are using a proteomic approach that combines two-dimensional electrophoresis and tandem mass spectrometry to detect and identify proteins that are differentially expressed in a cell line that is resistant to oxidative stress. The resistant cell line (OC14 cells) was developed previously through chronic exposure of a parent cell line (HA1 cells) to increasing hydrogen peroxide concentrations. Biochemical analyses of this system by other investigators have identified elevated content and activity of several classical antioxidant proteins that have established roles in oxidative stress resistance, but do not provide a complete explanation of this resistance. The proteomics studies described here have identified the enzyme aldose reductase (AR) as 4-fold more abundant in the resistant OC14 cells than in the HA1 controls. Based on this observation, the role of AR in the resistant phenotype was investigated by using a combination of AR induction with ethoxyquin and AR inhibition with Alrestatin to test the cytotoxicity of two oxidation-derived aldehydes: acrolein and glycolaldehyde. The results show that AR induction in HA1 cells provides protection against both acrolein- and glycolaldehyde-induced cytotoxicity. Furthermore, glutathione depletion sensitizes the cells to the acrolein-induced toxicity, but not the glycolaldehyde-induced toxicity, while AR inhibition sensitizes the cells to both acrolein- and glycolaldehyde-induced. These observations are consistent with a significant role for AR in the oxidative stress-resistant phenotype. These studies also illustrate the productive use of proteomic methods to investigate the molecular mechanisms of oxidative stress.
Rapid Inhibition of Cancer Cell Growth Induced by Lentiviral Delivery and Expression of Mutant-template Telomerase RNA and Anti-telomerase Short-interfering RNA
Cancer Research. Jul, 2004 | Pubmed ID: 15256453
In human cancers, telomeres are commonly maintained by elevated levels of the ribonucleoprotein enzyme telomerase, which contains an intrinsic templating RNA moiety (human telomerase RNA; hTER) and the core protein (human telomerase reverse transcriptase). We developed a lentiviral system for efficient overexpression of mutant-template human telomerase RNA (MT-hTer) to add mutant DNA to telomeres in cancer cells. We show that such MT-hTer overexpression rapidly inhibits cell growth and induces apoptosis in telomerase-positive precancerous or cancer cells but not in telomerase-negative cells. These rapid effects occurred independent of wild-type p53 and telomere length. Tumor growth and progression were significantly decreased in xenografts of human tumor cells overexpressing MT-hTers. Expression of a hairpin short-interfering RNA that specifically targeted the endogenous wild-type hTER template region, but spared the MT-hTers, also caused p53-independent cell growth inhibition and apoptosis, and when coexpressed with MT-hTer, synergistically killed cancer cells. Hence, anti-wild-type-hTER short-interfering RNA and MT-hTers may act through distinct pathways and, particularly in combination, represent a promising approach to anticancer therapies.
Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Aug, 2004 | Pubmed ID: 15297398
To test ribozymes targeting mouse telomerase RNA (mTER) for suppression of the progression of B16-F10 murine melanoma metastases in vivo.
Cellular and Gene Expression Responses Involved in the Rapid Growth Inhibition of Human Cancer Cells by RNA Interference-mediated Depletion of Telomerase RNA
The Journal of Biological Chemistry. Jun, 2005 | Pubmed ID: 15831499
Inhibition of the up-regulated telomerase activity in cancer cells has previously been shown to slow cell growth but only after prior telomere shortening. Previously, we have reported that, unexpectedly, a hairpin short interfering RNA specifically targeting human telomerase RNA rapidly inhibits the growth of human cancer cells independently of p53 or telomere length and without bulk telomere shortening (Li, S., Rosenberg, J. E., Donjacour, A. A., Botchkina, I. L., Hom, Y. K., Cunha, G. R., and Blackburn, E. H. (2004) Cancer Res. 64, 4833-4840). Here we have demonstrated that such telomerase RNA knockdown in cancer cells does not cause telomere uncapping but rather induces changes in the global gene expression profile indicative of a novel response pathway, which includes suppression of specific genes implicated in angiogenesis and metastasis, and is distinct from the expression profile changes induced by telomere-uncapping mutant template telomerase RNAs. These cellular responses to depleting telomerase in human cancer cells together suggest that cancer cells are "telomerase-addicted" and uncover functions of telomerase in tumor growth and progression in addition to telomere maintenance.
Spectrometric and Voltammetric Investigation of Interaction of Neutral Red with Calf Thymus DNA: PH Effect
Biophysical Chemistry. Oct, 2005 | Pubmed ID: 16051423
The interaction of neutral red (NR) with calf thymus DNA (CT DNA) was investigated by spectrometric (UV-vis, circular dichroism and fluorescence) and voltammetric techniques. It was shown that the interaction of NR with DNA depended on the values of R (R is defined as the ratio of the concentration of NR to that of CT DNA) and pH of the solution. NR intercalated into CT DNA base pairs at lower R value (R < 2.4) and following by NR aggregating along the helical surface of DNA at higher R value (R > 2.4) in pH 6.0 solution. Interestingly, we found that at lower R value, NR intercalated into CT DNA with its long axis perpendicular or parallel to the dyad axis of DNA in the solution of pH 6.0. While in pH 7.0 solution, NR bound with CT DNA through intercalation and electrostatic interactions. The electrochemical inactive complexes, NR-2CT DNA, 3NR-CT DNA, and NR-CT DNA were formed when NR interacted with nucleic acids in pH 6.0 and 7.2 solutions, respectively. The corresponding intrinsic binding constants for these complexes were obtained by UV-vis and fluorescence spectrometric methods, respectively. The CD spectra showed that the conformation of CT DNA was converted from right-handed B-DNA to left-handed Z-DNA due to the aggregating of NR along the surface of DNA in pH 6.0 solution, whereas a conversion from B-DNA to C-DNA was induced due to the interaction of DNA with NR in pH 7.2 solution. Finally, two binding modes of NR with CT DNA in aqueous with different values of pH were shown in the scheme.
Crystal Structure of the First KH Domain of Human Poly(C)-binding Protein-2 in Complex with a C-rich Strand of Human Telomeric DNA at 1.7 A
The Journal of Biological Chemistry. Nov, 2005 | Pubmed ID: 16186123
Recognition of poly(C) DNA and RNA sequences in mammalian cells is achieved by a subfamily of the KH (hnRNP K homology) domain-containing proteins known as poly(C)-binding proteins (PCBPs). To reveal the molecular basis of poly(C) sequence recognition, we have determined the crystal structure, at 1.7-A resolution, of PCBP2 KH1 in complex with a 7-nucleotide DNA sequence (5'-AACCCTA-3') corresponding to one repeat of the human C-rich strand telomeric DNA. The protein-DNA interaction is mediated by the combination of several stabilizing forces including hydrogen bonding, electrostatic interactions, van der Waals contacts, and shape complementarities. Specific recognition of the three cytosine residues is realized by a dense network of hydrogen bonds involving the side chains of two conserved lysines and one glutamic acid. The co-crystal structure also reveals a protein-protein dimerization interface of PCBP2 KH1 located on the opposite side of the protein from the DNA binding groove. Numerous stabilizing protein-protein interactions, including hydrophobic contacts, stacking of aromatic side chains, and a large number of hydrogen bonds, indicate that the protein-protein interaction interface is most likely genuine. Interaction of PCBP2 KH1 with the C-rich strand of human telomeric DNA suggests that PCBPs may participate in mechanisms involved in the regulation of telomere/telomerase functions.
Cytochrome C Superstructure Biocomposite Nucleated by Gold Nanoparticle: Thermal Stability and Voltammetric Behavior
Biomacromolecules. Nov-Dec, 2005 | Pubmed ID: 16283723
The thermal stability of cytochrome c (cyt c) after Au-nanoparticle-directed association has been studied by various spectroscopic (electronic absorption, resonance Raman, and circular dichroism) and electrochemical methods. The results show that the thermal stability of the Au-cyt c superstructure biocomposite formed by the electrostatic and hydrophobic interactions among the associated proteins increases significantly. It is mainly caused by strong hydrophobicity of the associated cyt c in Au-cyt c superstructure at high temperature, which results from the compact secondary structure and the packing of hydrophobic side chains around the Trp 59 and heme. In addition, the formation of bis-His configuration of heme is facilitated by the tightly self-associated state of cyt c in the Au-cyt c superstructure. The electrostatic coupling of the opposite charges among shells of the adsorbed proteins due to the formation of the superstructure biocomposite can reduce repulsions among the same charges in protein. These factors are also important for enhancing the stability of the associated cyt c. Furthermore, the voltammetric behavior of Au-cyt c at DNA modified glassy carbon electrode has been investigated for extending the application of Au-cyt c.
Biophysical Chemistry. Jun, 2006 | Pubmed ID: 16494994
Conformational changes of beta-lactoglobulin (beta-LG) induced by anionic phospholipid (dimyristoylphosphatidylglycerol, DMPG) at physiological conditions (pH 7.0) have been investigated by UV-VIS, circular dichroism (CD) and fluorescence spectra. The experimental results suggest that beta-LG-DMPG interactions cause beta-LG a structural reorganization of the secondary structure elements accompanied by an increase in alpha-helical content, and a loosening of the protein tertiary structure. The interaction forces between beta-LG and DMPG are further evaluated by fluorescence spectra. The fluorescence spectral data show that conformational changes in the protein are driven by electrostatic interaction at first, then by hydrophobic interaction between a protein with a negative net charge and a negatively charged phospholipid.
Proceedings of the National Academy of Sciences of the United States of America. Jul, 2006 | Pubmed ID: 16847266
Recent studies have demonstrated a role for telomerase in driving tumor progression, but its mechanism of action remains unclear. Here we show that stable, ribozyme-mediated suppression of mouse telomerase RNA reduced telomerase RNA expression, telomerase activity, and telomere length, which significantly reduced tumor invasion and metastatic potential. Our studies reveal that previously unidentified effects of telomerase may mediate its tumor-promoting effects. First, reducing telomerase activity induced a more dendritic morphology, accompanied by increased melanin content and increased expression of tyrosinase, a key enzyme in melanin biosynthesis. Second, gene expression profiling revealed that telomerase targeting down-regulated expression of several glycolytic pathway genes, with a corresponding decrease in glucose consumption and lactate production. Thus, telomerase activity controls the glycolytic pathway, potentially altering the energy state of tumor cells and thereby modulating tyrosinase activity and melanin production. These studies have important implications for understanding the mechanisms by which telomerase promotes tumor invasion and metastasis.
[Evaluation on the Sustainable Elimination of Iodine Deficiency Disorders in Jiangsu Province After Universal Salt Iodization for Ten Years]
Zhonghua Liu Xing Bing Xue Za Zhi = Zhonghua Liuxingbingxue Zazhi. Sep, 2006 | Pubmed ID: 17299974
PH-dependent Protein Conformational Changes in Albumin:gold Nanoparticle Bioconjugates: a Spectroscopic Study
Langmuir : the ACS Journal of Surfaces and Colloids. Feb, 2007 | Pubmed ID: 17249699
The conformational changes of bovine serum albumin (BSA) in the albumin:gold nanoparticle bioconjugates were investigated in detail by various spectroscopic techniques including UV-vis absorption, fluorescence, circular dichroism, and Fourier transform infrared spectroscopies. Our studies suggested that albumin in the bioconjugates that was prepared by the common adsorption method underwent substantial conformational changes at both secondary and tertiary structure levels. BSA was found to adopt a more flexible conformational state on the boundary surface of gold nanoparticles as a result of the conformational changes in the bioconjugates. The conformational changes at pH 3.8, 7.0, and 9.0, which corresponded to different isomeric forms of albumin, were investigated, respectively, to probe the pH effect on the conformational changes of BSA in the bioconjugates. The results showed that the pH of the medium influenced the changes greatly and that fluorescence and circular dichroism studies further indicated that the changes were larger at higher pH.
Cell Cycle (Georgetown, Tex.). Mar, 2007 | Pubmed ID: 17312399
To date, the major function attributed to telomerase has been the elongation of telomeres. Recent studies have assigned new biochemical properties to telomerase by implicating a role in tumor metastasis and cellular differentiation by virtue of its modulation of novel cell signaling pathways such as glycolysis. In this Perspective we will discuss these recent results that have provided additional insight into the involvement of telomerase in cellular processes other than telomere maintenance at chromosome ends.
Development of a Microfluidic Device for Detection of Pathogens in Oral Samples Using Upconverting Phosphor Technology (UPT)
Annals of the New York Academy of Sciences. Mar, 2007 | Pubmed ID: 17435143
Confirmatory detection of diseases, such as HIV and HIV-associated pathogens in a rapid point-of-care (POC) diagnostic remains a goal for disease control, prevention, and therapy. If a sample could be analyzed onsite with a verified result, the individual could be counseled immediately and appropriate therapy initiated. Our group is focused on developing a microfluidic "lab-on-a-chip" that will simultaneously identify antigens, antibodies, RNA, and DNA using a single oral sample. The approach has been to design individual modules for each assay that uses similar components (e.g., valves, heaters, metering chambers, mixers) installed on a polycarbonate base with a common reporter system. Assay miniaturization reduces the overall analysis time, increases accuracy by simultaneously identifying multiple targets, and enhances detector sensitivity by upconverting phosphor technology (UPT). Our microfluidic approach employs four interrelated components: (1) sample acquisition-OraSure UPlink collectors that pick-up and release bacteria, soluble analytes, and viruses from an oral sample; (2) microfluidic processing-movement of microliter volumes of analyte, target analyte extraction and amplification; (3) detection of analytes using UPT particles in a lateral flow system; and (4) software for processing the results. Ultimately, the oral-based microscale diagnostic system will detect viruses and bacteria, associated pathogen antigens and nucleic acids, and antibodies to these pathogens.
Preparation of DNA-silver Nanohybrids in Multilayer Nanoreactors by in Situ Electrochemical Reduction, Characterization, and Application
Langmuir : the ACS Journal of Surfaces and Colloids. Jul, 2007 | Pubmed ID: 17552547
Novel nanocomposite films containing DNA-silver nanohybrids have been successfully fabricated by combined use of the layer-by-layer self-assembly technique and an in situ electrochemical reduction method with the DNA-Ag+ complex as one of the building blocks. UV-vis absorption spectroscopy was employed to monitor the buildup of the multilayer films, which suggested a progressive deposition with almost an equal amount of the DNA-Ag+ complex in each cycle. The following electrochemical reduction of silver resulted in the formation of metal nanoparticles in the film, which was evidenced by the evolution of the intense plasmon absorption band originating from silver. Scanning electron microscopy indicated that the particles formed in the multilayer films possessed good monodispersity and stability, thanks to the surrounding polymers. X-ray photoelectron spectroscopy further confirmed the presence of the main components (such as DNA and metallic silver) of the nanocomposite films. In addition, we show that the size of the metal nanoparticles and the optical property of the film could be readily tuned by manipulating the assembly conditions. Furthermore, the feasibility of the as-prepared nanocomposite films functioning as a surface-enhanced Raman scattering active substrate for sensing purposes was investigated, and the results showed great enhancement of the Raman signal of two probe molecules, Rhodamine 6G and 4-aminothiophenol.
Biomacromolecules. Jul, 2007 | Pubmed ID: 17563113
Supramolecular organized multilayers were constructed by multiwalled carbon nanotubes modified with ferrocene-derivatized poly(allylamine) redox polymer and glucose oxidase by electrostatic self-assembly. From the analysis of voltammetric signals and fluorescence results, a linear increment of the coverage of enzyme per bilayer was estimated, which demonstrated that the multilayer is constructed in a spatially ordered manner. The cyclic voltammograms obtained from the indium tin oxide (ITO) electrodes coated by the (Fc-PAH@CNT/GOx)n multilayers revealed that bioelectrocatalytic response is directly correlated to the number of deposited bilayers; that is, the sensitivity is tunable by controlling the number of bilayers associated with ITO electrodes. The incorporation of redox-polymer-functionalized carbon nanotubes (CNT) into enzyme films resulted in a 6-10-fold increase in the glucose electrocatalytic current; the bimolecular rate constant of FADH2 oxidation (wiring efficiency) was increased up to 12-fold. Impedance spectroscopy data have yielded the electron diffusion coefficient (De) of this nanostructure to be over 10(-8) cm2 s(-1), which is typically higher than those systems without CNT by at least a factor of 10, indicating that electron transport in the new supramolecular architecture was enhanced by communication of the redox active site of enzyme, redox polymer, and CNT.
Safety and Tolerability of Ganoderma Lucidum in Healthy Subjects: a Double-blind Randomized Placebo-controlled Trial
The American Journal of Chinese Medicine. 2007 | Pubmed ID: 17597499
Ganoderma lucidum is a herbal medicine commonly used in oriental countries as a remedy for treating various medical conditions. In this controlled study, we evaluated the safety and tolerance of oral administration of Ganoderma lucidum in 16 human volunteers who received 2 grams of the extract or placebo twice daily for 10 consecutive days. During the study, information from subjective questionnaires were obtained, electrocardiograms, complete blood counts, blood chemistry analysis and urinalysis were performed. In addition, blood tests reflecting immunity were done. Our data showed that compared to placebo group, no adverse effects were observed after the extract intake. Although there were no obvious changes in CD4, CD8, and CD19 levels after the extract, CD56 cell count increased during the study and returned to baseline 10 days after the herbal intake. However, due to relatively high variability and small sample size, this CD56 increase did not achieve statistical significance, and remains to be re-evaluated in the future. It appears that an additional long-term safety and tolerance trial with herbal dose-escalating design is warranted.
Methods in Molecular Biology (Clifton, N.J.). 2007 | Pubmed ID: 18369821
More than 85% of human cancers and over 70% of immortalized human cell lines have highly elevated telomerase activity. In contrast, telomerase activity is down-regulated in most human adult somatic cells, except stem cells and germ cells. These results are consistent with telomerase conferring a selective advantage for continued proliferation of malignant cells and present a unique target for cancer gene therapy. In line with this view, our recent results suggest that knockdown of telomerase RNA in human or in mouse cancer cells by ribozyme or RNA interference (RNAi) diminishes telomerase activity and inhibits cancer cell growth both in vitro and in vivo. Such telomerase inhibiting agents represent a promising novel cancer therapeutic strategy. In this chapter, we will discuss the knockdown of telomerase RNA by hammerhead ribozyme and RNAi. Both techniques are mediated by sequence-specific recognition of target RNA by a guide RNA molecule, which then results in the nucleolytic degradation of the RNA target.
Enhanced Resonance Light Scattering Based on Biocatalytic Growth of Gold Nanoparticles for Biosensors Design
Biosensors & Bioelectronics. Feb, 2008 | Pubmed ID: 18068347
The biocatalytic growth of gold nanoparticles (Au-NPs) has been employed in the design of new optical biosensors based on the enhanced resonance light scattering (RLS) signals. Both absorption spectroscopy and transmission electron microscopy (TEM) analysis revealed Au-NP seeds could be effectively enlarged upon the reaction with H(2)O(2), an important metabolite that could be generated by many biocatalytic reactions. Upon the stepwise enlargement of Au-NPs, the light scattering intensity could be greatly enhanced, which then allowed the quantitative detection of the analyte, H(2)O(2). Further combination of the biocatalytic reaction that can yield H(2)O(2) by using the enzyme, glucose oxidase, with the enlargement of Au-NPs enabled the design of a sensitive glucose biosensor using the RLS technique. In the present study, we could achieve the detection of glucose in a linear range of 1.0 x 10(-6) M to 1.1 x 10(-4) M, with detection limit of 6.8 x 10(-7) M.
Facile Preparation of Water-soluble Fluorescent Silver Nanoclusters Using a Polyelectrolyte Template
Chemical Communications (Cambridge, England). Mar, 2008 | Pubmed ID: 18292899
We report a new approach for the synthesis of fluorescent and water-soluble Ag nanoclusters, using the common polyelectrolyte poly(methacrylic acid) as the template.
Effects of Long-term Chilling on Ultrastructure and Antioxidant Activity in Leaves of Two Cucumber Cultivars Under Low Light
Physiologia Plantarum. Apr, 2008 | Pubmed ID: 18334000
Cucumber (Cucumis sativus L.) cv. Xintaimici (a chilling-resistant cultivar) and cv. Jinyan no. 4 (a chilling-sensitive cultivar) were subjected to two temperatures (15/15 and 25/18 degrees C) under low light (100 mumol m(-2) s(-1)) to understand the relationship between ultrastructural changes and the antioxidant abilities caused by low temperature (15/15 degrees C). We also aimed to find indicators for chilling resistance that could be used on a routine basis in breeding programs of greenhouse crops. At the 15/15 degrees C treatment, the membranes of chloroplast, mitochondrion, ER and plasma were not significantly changed in Xintaimici, whereas they were seriously affected in Jinyan no. 4. This result was consistent with the changes of malonaldehyde in chilling-stressed cucumber leaves. The antioxidant activities were changed under low temperature according to cultivar-expected resistance, relating in part to the described ultrastructural changes. The activities of superoxide dismutase (EC 126.96.36.199) and guaiacol peroxidase (EC 188.8.131.52) increased in chilling-stressed leaves of both cultivars, but the two enzymes were not responsible for the difference between cucumber cultivars. At 15/15 degrees C, contents of GSH and activities of glutathione reductase (GR, EC 184.108.40.206) increased more in leaves of Xintaimici than in those of Jinyan no. 4, while catalase (CAT, EC 220.127.116.11) activities decreased less. GSH, GR and CAT were affected by low temperature and cultivars and correlated with the difference in ultrastructure between chilling-stressed cucumber cultivars. We propose that the three antioxidants might be therefore used as biochemical indicators to screen chilling-resistant cucumber cultivars.
A Biofuel Cell with Enhanced Performance by Multilayer Biocatalyst Immobilized on Highly Ordered Macroporous Electrode
Biosensors & Bioelectronics. Oct, 2008 | Pubmed ID: 18495469
A one-compartment glucose/O(2) biofuel cell based on an electrostatic layer-by-layer (LbL) technique on three-dimensional ordered macroporous (3DOM) gold electrode was described. A 3DOM gold electrode was synthesized electrochemically by an inverted colloidal crystal template technique. Then the macroporous gold electrodes were functionalized with Au nanoparticles (AuNPs) and enzyme, glucose dehydrogenase (GDH) or laccase. The (AuNPs/GDH)(n) multilayer modified macroporous gold electrode showed excellent bioelectrocatalytic activity towards glucose. The direct electroreduction towards oxygen was realized at (AuNPs/laccase)(n) films on 3DOM gold electrodes. The maximum power density of the cell with the macroporous film as matrix was 178 microW cm(-2) at 226 mV, which was 16 times larger than that of the biofuel cell with the flat electrode under the same condition. The proposed method is simple and would be applicable to enhance the power output of miniaturized biofuel cell.
Highly Ordered Mesoporous Carbons As Electrode Material for the Construction of Electrochemical Dehydrogenase- and Oxidase-based Biosensors
Biosensors & Bioelectronics. Nov, 2008 | Pubmed ID: 18541421
In this work, the excellent catalytic activity of highly ordered mesoporous carbons (OMCs) to the electrooxidation of nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)) was described for the construction of electrochemical alcohol dehydrogenase (ADH) and glucose oxidase (GOD)-based biosensors. The high density of edge-plane-like defective sites and high specific surface area of OMCs could be responsible for the electrocatalytic behavior at OMCs modified glassy carbon electrode (OMCs/GE), which induced a substantial decrease in the overpotential of NADH and H(2)O(2) oxidation reaction compared to carbon nanotubes modified glassy carbon electrode (CNTs/GE). Such ability of OMCs permits effective low-potential amperometric biosensing of ethanol and glucose, respectively, at Nafion/ADH-OMCs/GE and Nafion/GOD-OMCs/GE. Especially, as an amperometric glucose biosensor, Nafion/GOD-OMCs/GE showed large determination range (500-15,000 micromoll(-1)), high sensitivity (0.053 nA micromol(-1)), fast (9+/-1s) and stable response (amperometric response retained 90% of the initial activity after 10h stirring of 2 mmoll(-1) glucose solution) to glucose as well as the effective discrimination to the possible interferences, which may make it to readily satisfy the need for the routine clinical diagnosis of diabetes. By comparing the electrochemical performance of OMCs with that of CNTs as electrode material for the construction of ADH- and GOD-biosensors in this work, we reveal that OMCs could be a favorable and promising carbon electrode material for constructing other electrochemical dehydrogenase- and oxidase-based biosensors, which may have wide potential applications in biocatalysis, bioelectronics and biofuel cells.
A Sensitive NADH and Glucose Biosensor Tuned by Visible Light Based on Thionine Bridged Carbon Nanotubes and Gold Nanoparticles Multilayer
Biosensors & Bioelectronics. Dec, 2008 | Pubmed ID: 18818067
A NADH and glucose biosensor based on thionine cross-linked multiwalled carbon nanotubes (MWNTs) and Au nanoparticles (Au NPs) multilayer functionalized indium-doped tin oxide (ITO) electrode were presented in this paper. The effect of light irradiation on the enhancement of bioelectrocatalytic processes of the biocatalytic systems by the photovoltaic effect was investigated. This bioelectrode exhibited excellent catalytic activity of the oxidation towards dihydronicotinamide adenine dinucleotide (NADH). Most interesting, the performance of this NADH sensor could be tuned by the visible light. When the biosensor was performed in the dark, the anodic current increased linearly with NADH concentration over the range from 0.5 to 237 microM with detection limit 0.1 microM and sensitivity 17 nA microM(-1). The sensitivity became 115 nA microM(-1) with detection limit 0.05 microM with the light irradiation. Compared with the reaction in dark, the sensitivity increased around 7 folds while the detection limit decreased 2 folds. The glucose biosensor also exhibited the same behavior. The linear range was from 10 microM to 2.56 mM with the sensitivity of 7.8 microAmM(-1) and detection limit 5.0 microM in the dark. After the light irradiation, the linear range was from 1 microM to 3.25 mM with the sensitivity of 18.5 microA mM(-1) and detection limit 0.7 microM. It indicated a potential to provide an operational access to develop new kinds of photocontrolled dehydrogenase enzyme-based bioelectronics.
Detection of Neurotransmitters by a Light Scattering Technique Based on Seed-mediated Growth of Gold Nanoparticles
Nanotechnology. Mar, 2008 | Pubmed ID: 21817669
A simple light scattering detection method for neurotransmitters has been developed, based on the growth of gold nanoparticles. Neurotransmitters (dopamine, L-dopa, noradrenaline and adrenaline) can effectively function as active reducing agents for generating gold nanoparticles, which result in enhanced light scattering signals. The strong light scattering of gold nanoparticles then allows the quantitative detection of the neurotransmitters simply by using a common spectrofluorometer. In particular, Au-nanoparticle seeds were added to facilitate the growth of nanoparticles, which was found to enhance the sensing performance greatly. Using this light scattering technique based on the seed-mediated growth of gold nanoparticles, detection limits of 4.4 × 10(-7) M, 3.5 × 10(-7) M, 4.1 × 10(-7) M, and 7.7 × 10(-7) M were achieved for dopamine, L-dopa, noradrenaline and adrenaline, respectively. The present strategy can be extended to detect other biologically important molecules in a very fast, simple and sensitive way, and may have potential applications in a wide range of fields.
Biosensors & Bioelectronics. Feb, 2009 | Pubmed ID: 18823770
In this work, we report the application of novel, water-soluble fluorescent Ag clusters in fluorescent sensors for detecting cysteine, an important biological analyte. The fluorescence of poly(methacrylic acid) (PMAA)-templated Ag clusters was found to be quenched effectively by cysteine, but not when the other alpha-amino acids were present. By virtue of the specific response, a new, simple, and sensitive fluorescent method for detecting cysteine has been developed based on Ag clusters. The present assay allows for the selective determination of cysteine in the range of 2.5 x 10(-8) to 6.0 x 10(-6)M with a detection limit of 20 nM at a signal-to-noise ratio of 3. Based on the absorption and fluorescence studies, we suggested that cysteine quenched the emission by the thiol-adsorption-accelerated oxidation of the emissive Ag clusters. The present study shows a promising step toward the application of silver clusters, a new class of attractive fluorescence probes.
The Analyst. Jan, 2009 | Pubmed ID: 19082182
A new fluorescent sensor for the sensitive and selective detection of cyanide (CN(-)) in aqueous media was developed herein. The sensing approach is based on CN(-)-modulated quenching behavior of Cu(2+) toward the photoluminescence (PL) of CdTe quantum dots (QDs). In the presence of CN(-), the PL of QDs that have been quenched by Cu(2+) was found to be efficiently recovered, which then allows the detection of CN(-) in a very simple approach. Experimental results showed that the pH of the buffer solution, concentration of copper ions, and size of CdTe QDs all influenced the response of the sensor to CN(-). Under the optimal conditions, a good linear relationship between the PL intensity and the concentration of CN(-) can be obtained in the range of 3.0 x 10(-7) to 1.2 x 10(-5) M, with a detection limit as low as 1.5 x 10(-7) M. In addition, the present fluorescent sensor possesses remarkable selectivity for cyanide over other anions, and negligible influences were observed on the cyanide detection by the coexistence of other anions or biological species (such as albumin and typical blood constituents). Therefore, we expect the proposed copper ion-modified QDs to be an efficient and reliable sensing system to monitor cyanide concentration in environmental or clinical applications.
Electrochemiluminescence Detection of NADH and Ethanol Based on Partial Sulfonation of Sol-gel Network with Gold Nanoparticles
Biosensors & Bioelectronics. Mar, 2009 | Pubmed ID: 19110411
We developed a stable, sensitive electrochemiluminescence (ECL) biosensor based on the synthesis of a new sol-gel material with the ion-exchange capacity sol-gel to coimmobilize the Ru(bpy)(3)(2+) and enzyme. The partial sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) film acted as both an ion exchanger for the immobilization of Ru(bpy)(3)(2+) and a matrix to immobilize gold nanoparticles (AuNPs). The AuNPs/PSSG/Ru(bpy)(3)(2+) film modified electrode allowed sensitive the ECL detection of NADH as low as 1 nM. Such an ability of AuNPs/PSSG/Ru(bpy)(3)(2+) film to promote the electron transfer between Ru(bpy)(3)(2+) and the electrode suggested a new, promising biocompatible platform for the development of dehydrogenase-based ECL biosensors. With alcohol dehydrogenase (ADH) as a model, we then constructed an ethanol biosensor, which had a linear range of 5 microM to 5.2 mM with a detection limit of 12nM.
Cdk1-dependent Phosphorylation of Cdc13 Coordinates Telomere Elongation During Cell-cycle Progression
Cell. Jan, 2009 | Pubmed ID: 19135888
Elongation of telomeres by telomerase replenishes the loss of terminal telomeric DNA repeats during each cell cycle. In budding yeast, Cdc13 plays an essential role in telomere length homeostasis, partly through its interactions with both the telomerase complex and the competing Stn1-Ten1 complex. Previous studies in yeast have shown that telomere elongation by telomerase is cell cycle dependent, but the mechanism underlying this dependence is unclear. In S. cerevisiae, a single cyclin-dependent kinase Cdk1 (Cdc28) coordinates the serial events required for the cell division cycle, but no Cdk1 substrate has been identified among telomerase and telomere-associated factors. Here we show that Cdk1-dependent phosphorylation of Cdc13 is essential for efficient recruitment of the yeast telomerase complex to telomeres by favoring the interaction of Cdc13 with Est1 rather than the competing Stn1-Ten1 complex. These results provide a direct mechanistic link between coordination of telomere elongation and cell-cycle progression in vivo.
Design of Fluorescent Assays for Cyanide and Hydrogen Peroxide Based on the Inner Filter Effect of Metal Nanoparticles
Analytical Chemistry. Feb, 2009 | Pubmed ID: 19140677
We have demonstrated the design of a new type fluorescent assay based on the inner filter effect (IFE) of metal nanoparticles (NPs), which is conceptually different from the previously reported metal NPs-based fluorescent assays. With a high extinction coefficient and tunable plasmon absorption feature, metal NPs are expected to be capable of functioning as a powerful absorber to tune the emission of the fluorophore in the IFE-based fluorescent assays. In this work, we presented two proof-of-concept examples based on the IFE of Au NPs by choosing MDMO-PPV as a model fluorophore, whose fluorescence could be tuned by the absorbance of Au NPs with a much higher sensitivity than the corresponding absorbance approach. While the first assay worked in a turn-on mode upon the etching of Au NPs by the analyte, CN(-), the second one functioned in a turn-off mode upon the catalytic growth of Au NPs by the analyte, H(2)O(2). As a result, the present IFE-based approach can detect cyanide ranging from 1.0 x 10(-6) to 6.0 x 10(-4) M with a detection limit of 6.0 x 10(-7) M and H(2)O(2) ranging from 1.5 x 10(-7) to 2.2 x 10(-5) M with a detection limit of 8.5 x 10(-8) M, respectively. Notably, the present IFE-based approach allows the design of fluorescent assays in a more simple, time-saving, and economical approach when compared with conventional metal NPs-based fluorescent assays, since no modification step of the fluorophore was needed any more.
Biosensors & Bioelectronics. May, 2009 | Pubmed ID: 19321330
This study demonstrates a novel compartment-less glucose/O(2) biofuel cell (BFC) based on highly ordered mesoporous carbons (OMCs) with three-dimensionally (3D) interconnected and ordered pore structures. OMCs are used as supports for both stably confining the electrocatalyst (i.e., meldola's blue, MDB) for NADH oxidation and the anodic biocatalyst (i.e., NAD(+)-dependent glucose dehydrogenase, GDH) for glucose oxidation, and for facilitating direct electrochemistry of the cathodic biocatalyst (i.e., laccase, LAC) for O(2) electroreduction. In 0.10 M pH 6.0 PBS containing 20 mM NAD(+) and 60 mM glucose under the air-saturated atmosphere, the open circuit voltage (0.82 V) and the maximum power output (38.7 microW cm(-2) (at 0.54 V)) of the assembled compartment-less OMCs-based BFC are both higher than those of carbon nanotubes (CNTs)-based BFC (0.75 V and 2.1 microW cm(-2) (at 0.46 V)). These may make OMCs to be another kind of robust and advanced carbon electrode material besides CNTs for BFCs applications.
Expression of Toll-like Receptor 4 in Uvea-resident Tissue Macrophages During Endotoxin-induced Uveitis
Molecular Vision. 2009 | Pubmed ID: 19347047
To investigate the dynamics and distribution of toll-like receptor 4 (TLR4)-positive cells and resident tissue macrophages in the uvea during endotoxin-induced uveitis (EIU) in Wistar rats.
Sensitive Turn-on Fluorescent Detection of Cyanide Based on the Dissolution of Fluorophore Functionalized Gold Nanoparticles
Chemical Communications (Cambridge, England). Jun, 2009 | Pubmed ID: 19462092
We report a simple fluorescent method for sensitive cyanide detection based on the dissolution of Rhodamine B-adsorbed gold nanoparticles by cyanide.
The Analyst. Jul, 2009 | Pubmed ID: 19562218
A simple, sensitive fluorescent method for detecting cyanide has been developed based on the inner filter effect (IFE) of silver nanoparticles (Ag NPs). With a high extinction coefficient and tunable plasmon absorption feature, Ag NPs are expected to be a powerful absorber to tune the emission of the fluorophore in the IFE-based fluorescent assays. In the present work, we developed a turn-on fluorescent assay for cyanide based on the strong absorption of Ag NPs to both excitation and emission light of an isolated fluorescence indicator. In the presence of cyanide, the absorber Ag NPs will dissolve gradually, which then leads to recovery of the IFE-decreased emission of the fluorophore. The concentration of Ag NPs in the detection system was found to affect the fluorescence response toward cyanide greatly. Under the optimum conditions, the present IFE-based approach can detect cyanide ranging from 5.0 x 10(-7) to 6.0 x 10(-4) M with a detection limit of 2.5 x 10(-7) M, which is much lower than the corresponding absorbance-based approach and compares favorably with other reported fluorescent methods. In addition, the present method possesses a good selectivity for cyanide over other common anions and further application in cyanide-spiked water samples suggested a recovery between 98.2 and 101.4%. Therefore, our proposed IFE-based fluorescent method is expected to be applied for cyanide determination in practical applications.
Nanocomposite Based on Depositing Platinum Nanostructure Onto Carbon Nanotubes Through a One-pot, Facile Synthesis Method for Amperometric Sensing
Talanta. Oct, 2009 | Pubmed ID: 19635352
Platinum nanoparticles (Pt NPs) were deposited onto multi-walled carbon nanotubes (MWNTs) through direct chemical reduction without any other stabilizing agents. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry were employed to characterize the morphology of the as-prepared nanocomposite (noted as Pt NPs-MWNTs) and further identify the Pt NPs on the surface of MWNTs. The nanocomposite demonstrated the ability to electrocatalyze the oxidation of hydrogen peroxide and substantially raises the response current. A sensitivity of 591.33 microA mM(-1) cm(-2) was obtained at Pt NPs-MWNTs modified electrode. Thus, we immobilized glucose oxidase (GOD) as a model enzyme on the nanocomposite-based electrode with a thin layer of Nafion to fabricate a glucose biosensor, which showed sensitive and fast response to glucose. The influence of the GOD loading was investigated and the biosensor with an enzyme loading concentration of 10 mg/mL shows optimal performance for glucose detection, that is, a detection limit of 3 microM and a response time of 3s, respectively.
Biosensors & Bioelectronics. Oct, 2009 | Pubmed ID: 19683912
In this work, a new fluorescent method for sensitive detection of biological thiols in human plasma was developed using a near-infrared (NIR) fluorescent dye, FR 730. The sensing approach was based on the strong affinity of thiols to gold and highly efficient fluorescent quenching ability of gold nanoparticles (Au NPs). In the presence of thiols, the NIR fluorescence would enhance dramatically due to desorption of FR 730 from the surfaces of Au NPs, which allowed the analysis of thiol-containing amino acids in a very simple approach. The size of Au NPs was found to affect the fluorescent assay and the best response for cysteine detection was achieved when using Au NPs with the diameter of 24 nm, where a linear range of 2.5 x 10(-8)M to 4.0 x 10(-6)M and a detection limit of as low as 10nM was obtained. This method also demonstrated a high selectivity to thiol-containing amino acids due to the strong affinity of thiols to gold. An important feature of the method is that the present fluorescent assay works in the NIR region, which is particularly favorable for the optical detection/imaging of biological samples. The method was successfully applied to the determination of thiols in a complex multicomponent mixture such as human plasma, which suggests our proposed method has great potential for diagnostic purposes.
Organic-inorganic Hybrid Material for the Cells Immobilization: Long-term Viability Mechanism and Application in BOD Sensors
Biosensors & Bioelectronics. Oct, 2009 | Pubmed ID: 19726176
In this paper, organic-inorganic hybrid material, which is composed of silica and the grafting copolymer of poly (vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)), was employed to immobilize Trichosporon cutaneum strain 2.570 cells. Cells entrapped into the hybrid material were found to keep a long-term viability. The mechanism of such a long-term viability was investigated by using confocal laser scanning microscopy (CLSM). Our studies revealed that arthroconidia produced in the extracellular material might play an important role in keeping the long-term viability of the immobilized microorganism. After the arthroconidia were activated, an electrochemical biochemical oxygen demand (BOD) sensor based on cell/hybrid material-modified supporting membrane was constructed for verifying the proposed mechanism. The results and insight gained from the present experiments can be widely used to various biosensor designs.
Zhonghua Xin Xue Guan Bing Za Zhi. May, 2009 | Pubmed ID: 19781225
To observe the association between job stress (effort-reward imbalance model)and blood lipids among university staff in Yunnan province.
A Biofuel Cell with a Single-walled Carbon Nanohorn-based Bioanode Operating at Physiological Condition
Biosensors & Bioelectronics. Feb, 2010 | Pubmed ID: 20006485
Single-walled carbon nanohorns (SWNHs), a new type of carbon nanomaterials, possess excellent catalytic properties, high-purity, and low toxicities, which make them suitable for bioelectrochemical application. Here a biofuel cell anode has been developed by using SWNHs as the support for redox mediator and biocatalyst for the first time. Cyclic voltammetric results show SWNHs promotes the electropolymerization of methylene blue (MB) and the resulted nanocomposite (poly MB-SWNHs) exhibits prominent catalytic ability to the oxidation of nicotinamide adenine dinucleotide. Glucose dehydrogenase was then immobilized on the poly MB-SWNHs modified electrode for the oxidation of glucose. Employing Pt nanoparticles supported on functionalized TiO(2) colloidal spheres with nanoporous surface as cathode catalyst, the as-assembled glucose/O(2) biofuel cell operate at the physiological condition with good performance.
A Facile and Controllable Strategy to Synthesize Au-Ag Alloy Nanoparticles Within Polyelectrolyte Multilayer Nanoreactors Upon Thermal Reduction
Langmuir : the ACS Journal of Surfaces and Colloids. May, 2010 | Pubmed ID: 20017511
A new synthesis strategy has been developed for the preparation of bimetallic gold-silver (Au-Ag) alloy nanoparticles by the virtue of polyelectrolyte multilayer (PEM) nanoreactors. By controlling the assembly conditions, gold and silver ions can be effectively loaded onto the PEM composed of polyethylenimine (PEI) and poly(acrylic acid) (PAA) simultaneously. Upon further thermal treatment, Au-Ag alloy nanoparticles with sizes of ca. 3.8 nm formed in the PEM, which were characterized in detail by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and energy-dispersive X-ray (EDX) analysis. Appearance of a single plasmon band in the visible region and lack of apparent core-shell structures in the TEM images confirm the formation of homogeneous Au-Ag alloy nanoparticles. In addition, the surface plasmon absorption band of the Au-Ag alloy nanoparticles shows linear blue-shift with increasing Ag content, which also supported the formation of alloy nanoparticles. Several key parameters of the present strategy have been investigated, which showed that pH of both the assembly solution and gold salt solution and the choice of polymers for constructing PEM, as well as the reduction approach, all played an important role in successfully synthesizing bimetallic Au-Ag nanoparticles. The formation mechanism of alloy nanoparticles has also been discussed based on the spectral evolution during the thermal reduction.
Measuring Effort-reward Imbalance in School Settings: a Novel Approach and Its Association with Self-rated Health
Journal of Epidemiology. 2010 | Pubmed ID: 20037260
We attempted to apply the model of effort-reward imbalance (ERI) to school settings in order to measure students' psychosocial stress and analyze its association with self-rated health in adolescents.
Total Synthesis and Biological Evaluation of Largazole and Derivatives with Promising Selectivity for Cancers Cells
Organic Letters. Mar, 2010 | Pubmed ID: 20184338
The efficient total synthesis of the natural substance largazole is described. Using this strategy, a small library of largazole analogs was developed. Structure-activity relationship studies suggested that the geometry of the alkene in the side chain is critical. While the largazole's analogues with trans-alkene are potent for the antiproliferative effect, those with cis-alkene are completely inactive. Most importantly, replacement of valine with tyrosine in largazole increased selectivity toward human cancer cells over human normal cells more than 100-fold.
Talanta. Jun, 2010 | Pubmed ID: 20441880
Monitoring biochemical oxygen demand (BOD) by mediator method (BOD(Med)) has been developed for recent years and deaerated condition was generally adopted to avoid the effect of oxygen, but the deaerated condition was unfavorable in practical applications. Herein, we first proposed another way to explore non-deaerated BOD(Med) (called NDA-BOD(Med)) method utilizing ferricyanide, which was reduced by Escherichia coli upon catalyzing organic substrate to produce ferrocyanide. We attempted to explain the feasibility of NDA-BOD(Med) by the two aspects. Firstly, the obtained biodegradation efficiencies of the bacteria under the deaerated and non-deaerated conditions were similar, and the concentration of O(2) (0.25mM at 8mg/L O(2)) is 1-2 order of magnitude lower than that of mediator commonly used (55mM ferricyanide), so the effect of O(2) to measurements could be neglected. Secondly, the relationship between the artificial and the natural electron acceptor was investigated, and it was found that the oxygen consumption in the NDA-BOD(Med) measurement was mainly contributed to endogenous values. Furthermore, the performance of present NDA-BOD(Med) was reported, and this method was optimized for measuring the low-concentration samples, synthetic wastewater and real polluted wastewater. The NDA-BOD(Med) provides a simple and efficient way in rapid BOD determinations, especially advantageous for in situ monitoring of water system.
Sequential and Gamma-secretase-dependent Processing of the Betacellulin Precursor Generates a Palmitoylated Intracellular-domain Fragment That Inhibits Cell Growth
Journal of Cell Science. Jul, 2010 | Pubmed ID: 20530572
Betacellulin (BTC) belongs to the family of epidermal growth factor (EGF)-like growth factors that are expressed as transmembrane precursors and undergo proteolytic ectodomain shedding to release soluble mature ligands. BTC is a dual-specificity ligand for ErbB1 and ErbB4 receptors, and can activate unique signal-transduction pathways that are beneficial for the function, survival and regeneration of pancreatic beta-cells. We have previously shown that BTC precursor (proBTC) is cleaved by ADAM10 to generate soluble ligand and a stable, transmembrane remnant (BTC-CTF). In this study, we analyzed the fate of the BTC-CTF in greater detail. We demonstrated that proBTC is cleaved by ADAM10 to produce BTC-CTF, which then undergoes intramembrane processing by presenilin-1- and/or presenilin-2-dependent gamma-secretase to generate an intracellular-domain fragment (BTC-ICD). We found that the proBTC cytoplasmic domain is palmitoylated and that palmitoylation is not required for ADAM10-dependent cleavage but is necessary for the stability and gamma-secretase-dependent processing of BTC-CTF to generate BTC-ICD. Additionally, palmitoylation is required for nuclear-membrane localization of BTC-ICD, as demonstrated by the redistribution of non-palmitoylated BTC-ICD mutant to the nucleoplasm. Importantly, a novel receptor-independent role for BTC-ICD signaling is suggested by the ability of BTC-ICD to inhibit cell growth in vitro.
Biosensors & Bioelectronics. Sep, 2010 | Pubmed ID: 20627512
In this study, we reported on the construction of a stable single-chamber ethanol/O(2) biofuel cell harvesting energy from the ethanol and alcoholic beverage. We prepared a composite film which consisted of partially sulfonated (3-mercaptopropyl)-trimethoxysilane sol-gel (PSSG) and chitosan (CHI). The combination of ion-exchange capacity sol-gel and biopolymer chitosan not only provided the attached sites for mediator MDB and AuNPs to facilitate the electron transfer along the substrate reaction, but also gave the suitable microenvironment to retain the enzyme activity in long term. The ethanol bioanode was constructed with the film coimmobilized dehydrogenase (ADH), Meldola's blue (MDB) and gold nanoparticles (AuNPs). The MDB/AuNPs/PSSG-CHI-ADH composite modified electrode showed prominent electrocatalytic activity towards the oxidation of ethanol. The oxygen biocathode consisted of laccase and AuNPs immobilized on the PSSG-CHI composite membrane. The AuNPs/PSSG-CHI-laccase modified electrode catalyzed four-electron reduction of O(2) to water, without any mediator. The assembled single-chamber biofuel cell exhibited good stability and power output towards ethanol. The open-circuit voltage of this biofuel cell was 860 mV. The maximum power density of the biofuel cell was 1.56 mWcm(-2) at 550 mV. Most interestingly, this biofuel cell showed the similar performance when the alcoholic beverage acted as the fuel. When this biofuel cell ran with wine as the fuel, the maximum power output density was 3.21 mAcm(-2) and the maximum power density was 1.78 mWcm(-2) at 680 mV of the cell voltage. Our system exhibited stable and high power output in the multi-component substrate condition. This cell has great potential for the development and practical application of bioethanol fuel cell.
[Zhonghua Yan Ke Za Zhi] Chinese Journal of Ophthalmology. Apr, 2010 | Pubmed ID: 20654065
To investigate the dynamics and distribution of toll-like receptor 4 (TLR4) in uvea-resident tissue macrophages during endotoxin-induced uveitis (EIU) in Wistar rats.
AuAg Bimetallic Nanoparticles Film Fabricated Based on H2O2-mediated Silver Reduction and Its Application
Talanta. Jun, 2010 | Pubmed ID: 20685444
A method to fabricate AuAg bimetallic nanoparticles film by H(2)O(2)-mediated reduction of silver was reported. Gold nanoparticles (Au NPs) were first adsorbed onto the surface of a self-assembled 2-aminoethanethiol monolayer-modified gold film or 3-aminopropyltriethoxysilane (APTES) monolayer-modified quartz slide. Upon further treatment of this modified film with the solution containing silver nitrate (AgNO(3)) and H(2)O(2), silver was deposited on the surface of Au NPs. The size of the AuAg bimetallic particles could be readily tuned by manipulating the concentration of H(2)O(2). Surface plasmon resonance (SPR) was used to investigate the process, the deposition of silver on Au NPs modified gold film resulted in an obvious decrease of depth in the SPR reflectance intensity and minimum angle curves (SPR R-theta curves), which may be utilized for the quantitative SPR detection of the analyte, H(2)O(2). Combination of the biocatalytic reaction that could yield H(2)O(2) by using the enzyme, glucose oxidase, with the deposition of silver may enable the design of a glucose biosensor by SPR technique. Furthermore, we evaluated the AuAg bimetallic nanoparticles film for their ability to be an effective substrate for surface-enhanced Raman scattering (SERS).
Calycosin Promotes Angiogenesis Involving Estrogen Receptor and Mitogen-activated Protein Kinase (MAPK) Signaling Pathway in Zebrafish and HUVEC
PloS One. 2010 | Pubmed ID: 20686605
Angiogenesis plays an important role in a wide range of physiological processes, and many diseases are associated with the dysregulation of angiogenesis. Radix Astragali is a Chinese medicinal herb commonly used for treating cardiovascular disorders and has been shown to possess angiogenic effect in previous studies but its active constituent and underlying mechanism remain unclear. The present study investigates the angiogenic effects of calycosin, a major isoflavonoid isolated from Radix Astragali, in vitro and in vivo.
The Expression of Cytokines in the Aqueous Humor and Serum During Endotoxin-induced Uveitis in C3H/HeN Mice
Molecular Vision. 2010 | Pubmed ID: 20806043
The cytokines present in the aqueous humor and serum of C3H/HeN mice with endotoxin-induced acute anterior uveitis were analyzed, and the potential role of the cytokines in the pathogenesis of the disease was investigated.
Mediators of Inflammation. 2010 | Pubmed ID: 20847811
To observe the expression of Toll-like receptor-4 (TLR4), myeloid differentiation factor 88 (MyD88), and nuclear factor kappa B p65 (NF-ÎºB p65) in iris tissue during endotoxin-induced uveitis (EIU) and evaluate the significance of these factors in uveitis.
Work and Family Stress is Associated with Menstrual Disorders but Not with Fibrocystic Changes: Cross-sectional Findings in Chinese Working Women
Journal of Occupational Health. 2010 | Pubmed ID: 20944439
To explore the separate and combined effects of work and family stress on menstrual disorders and fibrocystic changes in Chinese working women.
Talanta. Nov, 2010 | Pubmed ID: 21035639
In this paper, we first reported the viable but nonculturable (VBNC) cells used for fabricating biosensor. The organic-inorganic hybrid material composed of silica and the grafting copolymer of poly(vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)) was used to immobilize microbial cells for biosensor fabrication. The VBNC cells were formed after the hybrid material dried, showing the cell walls were sacrificed. With the intracellular enzymes as core and the "sacrificed" cell walls as shell, the present VBNC cells maybe considered as a core/shell structure. The extracellular material worked as the scaffold for core/shell structure. The core/shell structure and the scaffold structure were demonstrated by single-cell level image analysis using confocal laser scanning microscopy (CLSM). The electrochemical method was adopted for further examining the enzyme activity of VBNC cells. The VBNC cells did not need nutrient treatment and other physicochemical factors for cell growth, which is a significant contribution for storing biosensor. A glucose-glutamic acid biosensor fabricated by the VBNC cells exhibited long-term storage stability for 100 days.
Psychosocial Work Environment and Intention to Leave the Nursing Profession: Results from the Longitudinal Chinese NEXT Study
Scandinavian Journal of Public Health. Feb, 2010 | Pubmed ID: 21172773
A shortage of nurses happens not only in developed countries, but also in developing countries, such as in China, but the nurse turnover here makes the situation worse. Why do Chinese nurses want to leave the nursing profession? Our hypothesis is that unfavourable psychosocial work environment could predict nurses' intention to leave (ITL).
The American Journal of Emergency Medicine. Mar, 2011 | Pubmed ID: 20674236
Acute epiglottitis is a true airway emergency in the emergency department (ED). The patient may appear very toxic and rapidly progress to respiratory distress and life-threatening condition. The inflammatory process includes not only epiglottis but also the rest of the supraglottic area including the vallecula, aryepiglottic folds, and arytenoids. Soft tissue swelling over this windpipe area can be very dramatic. The criterion standard of diagnosis is direct inspection of cherry red and swollen epiglottis by laryngoscopy in the operation room with immediate access to anesthetists or ear, nose, and throat specialists. However, before the patients are well prepared, the clinical condition may critically go downhill; and any intention to visualize the throat can result in severe and fatal airway spasm. Thumbprint sign on lateral radiography of neck is typical, but it may be extremely risky to let a patient leave the consulting room for the study if respiratory distress has developed. We demonstrate a safe and practical way to investigate the epiglottis by bedside ultrasonography to visualize the "alphabet P sign" in a longitudinal view through thyrohyoid membrane by emergency physician in the ED.
Biosensors & Bioelectronics. Jan, 2011 | Pubmed ID: 20970316
In this work, biomolecule-stabilized Au nanoclusters were demonstrated as a novel fluorescence probe for sensitive and selective detection of glucose. The fluorescence of Au nanoclusters was found to be quenched effectively by the enzymatically generated hydrogen peroxide (H(2)O(2)). By virtue of the specific response, the present assay allowed for the selective determination of glucose in the range of 1.0×10(-5) M to 0.5×10(-3) M with a detection limit of 5.0×10(-6) M. The absorption spectroscopy, X-ray photoelectron spectroscopy (XPS) and fluorescence decay studies were then performed to discuss the quenching mechanism. In addition, we demonstrated the application of the present approach in real serum samples, which suggested its great potential for diagnostic purposes.
Zhongguo Fei Ai Za Zhi = Chinese Journal of Lung Cancer. Jan, 2011 | Pubmed ID: 21219832
uPA and ET-1 proteins have been reported to be up-regulated in some of human cancers. The aim of this study is to investigate the alteration and clinical relevance of uPA and ET-1 protein levels in non-small cell lung cancer (NSCLC).
Bioscience Reports. Jun, 2011 | Pubmed ID: 21250944
Telomeres are essential for the stability and complete replication of linear chromosomes. Telomere elongation by telomerase counteracts the telomere shortening due to the incomplete replication of chromosome ends by DNA polymerase. Telomere elongation is cell-cycle-regulated and coupled to DNA replication during S-phase. However, the molecular mechanisms that underlie such cell-cycle-dependent telomere elongation by telomerase remain largely unknown. Several aspects of telomere replication in budding yeast, including the modulation of telomere chromatin structure, telomere end processing, recruitment of telomere-binding proteins and telomerase complex to telomere as well as the coupling of DNA replication to telomere elongation during cell cycle progression will be discussed, and the potential roles of Cdk (cyclin-dependent kinase) in these processes will be illustrated.
Molecular Vision. 2011 | Pubmed ID: 21264236
To investigate the roles of activation of macrophages isolated from C3H/HeN and C3H/HeJ mice and stimulated by lipopolysaccharide (LPS), and toll-like receptor 4-mediated signal transduction in the development of acute anterior uveitis.
Nanoscale. May, 2011 | Pubmed ID: 21311796
We report a facile strategy to synthesize water-soluble, fluorescent gold nanoclusters (AuNCs) in one step by using a mild reductant, tetrakis(hydroxymethyl)phosphonium chloride (THPC). A zwitterionic functional ligand, D-penicillamine (DPA), as a capping agent endowed the AuNCs with excellent stability in aqueous solvent over the physiologically relevant pH range. The DPA-capped AuNCs displayed excitation and emission bands at 400 and 610 nm, respectively; the fluorescence quantum yield was 1.3%. The effect of borohydride reduction on the optical spectra and X-ray photoelectron spectroscopy (XPS) results indicated that the AuNC luminescence is closely related to the presence of Au(I) on their surfaces. In a first optical imaging application, we studied internalization of the AuNCs by live HeLa cells using confocal microscopy with two-photon excitation. A cell viability assay revealed good biocompatibility of these AuNCs. Our studies demonstrate a great potential of DPA-stabilized AuNCs as fluorescent nanoprobes in bioimaging and related applications.
Guang Pu Xue Yu Guang Pu Fen Xi = Guang Pu. Mar, 2011 | Pubmed ID: 21595201
The characteristics of striations in cylindrical hollow cathode discharge were investigated experimentally. The emission intensity and spectra of striations were measured, and the spatial characteristics of electron excitation temperature and relative electron density were calculated. It is shown that the emission intensity, the electron excitation temperature and the electron density appear as a periodic structure. The electrons have higher excitation temperature but lower density in the bright regions compared with the dark regions. The electron excitation temperature in the bright regions decreases from the cathode to the anode. It is also shown that the electron excitation temperature increases with increasing current.
Synthetic Routes and Biological Evaluation of Largazole and Its Analogues As Potent Histone Deacetylase Inhibitors
Molecules (Basel, Switzerland). Jun, 2011 | Pubmed ID: 21654576
Natural products with interesting biological properties and structural diversity have often served as valuable lead drug candidates for the treatment of various human diseases. Largazole, isolated from the marine cyanobacterium Symploca sp. has exhibited potent inhibitory activity against many cancer cell lines. Besides, it shows remarkable selectivity between transformed and nontransformed cells, which is the main disadvantage of other antitumor natural products such as paclitaxel and actinomycin D. Due to its potential as a potent and selective anticancer drug candidate, a great deal of attention has been focused on largazole and its analogues. It is the aim of this review to highlight synthetic aspects of largazole and its analogues as well as their preliminary structure-activity relationship studies.
Helicobacter. Aug, 2011 | Pubmed ID: 21762264
Helicobacter pylori infection appears to be a protective factor for gastroesophageal reflux disease (GERD). However, H. pylori is associated with the subtype of esophageal carcinoma, and long-term proton-pump inhibition usage would cause gastric atrophy in patients with persistent H. pylori infection, which is a precancerous lesion. The relationship between H. pylori infection and GERD is still unclear. We aimed to confirm whether the eradication of H. pylori would worsen or improve symptomatic or endoscopic GERD.
One-pot Synthesis of Near-infrared Fluorescent Gold Clusters for Cellular Fluorescence Lifetime Imaging
Small (Weinheim an Der Bergstrasse, Germany). Sep, 2011 | Pubmed ID: 21809441
A facile strategy to synthesize water-soluble fluorescent gold nanoclusters (Au NCs) stabilized with the bidentate ligand dihydrolipoic acid (DHLA) is reported. The DHLA-capped Au NCs are characterized by UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The Au NCs possess many attractive features including ultrasmall size, bright near-infrared luminescence, high colloidal stability, and good biocompatibility, making them promising imaging agents for biomedical and cellular imaging applications. Moreover, their long fluorescence lifetime (>100 ns) makes them attractive as labels in fluorescence lifetime imaging (FLIM) applications. As an example, the internalization of Au NCs by live HeLa cells is visualized using the FLIM technique.
Molecular BioSystems. Nov, 2011 | Pubmed ID: 21909574
Angiogenesis plays an important role in a wide range of physiological processes and many diseases are associated with the dysregulation of angiogenesis. The commonly used Chinese herbal medicine Radix Astragali (known as Huang qi in Chinese) is a potential candidate for treating this type of disease. Calycosin, a major isoflavonoid in Radix Astragali, was identified in our earlier study and shown to induce angiogenesis in human umbilical vein endothelial cells (HUVEC) in vitro and in zebrafish embryos in vivo. Using zebrafish as a testing model, we investigated the angiogenic effect of calycosin on the subintestinal vessels (SIVs) in zebrafish embryos. Our findings using transcriptional profiling by deep sequencing, and confirmed by quantitative real-time PCR (qPCR), demonstrate that calycosin modulated vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and ErbB signaling pathways. The inhibitory effects of calycosin-induced phenotypic responses by several pathway-specific inhibitors (VRI, SU5402, MEK1/2 Inhibitor, Wortmannin and LY294002) further identified the potential involvement of VEGF(R) and FGF(R) signaling pathways in the angiogenic activities of calycosin. We present a comprehensive framework of study using fluorescence microscopy, transcriptomics and qPCR to demonstrate the proangiogenic effects of calycosin in vivo. The data have elucidated the connection between morphological observations and genomic evidence, indicating the potential roles of several key signaling pathways in angiogenesis.
[Influence of SGHWJN Particles on Mediators of Inflammation in Esophageal Tissues of Rat with Reflux Esophagitis]
Zhongguo Zhong Yao Za Zhi = Zhongguo Zhongyao Zazhi = China Journal of Chinese Materia Medica. Sep, 2011 | Pubmed ID: 22121815
To study the influence of SGHWJN particles on inflammation and the mediators of inflammation in esophageal tissues of rat with reflux esophagitis.
Xenobiotica; the Fate of Foreign Compounds in Biological Systems. Mar, 2012 | Pubmed ID: 21961561
Although zebrafish has become a popular animal model for drug discovery and screening, drug metabolism in zebrafish remains largely unknown. In this study, we probed the metabolic capability of zebrafish larvae with calycosin, one of the major isoflavone constituents of Radix Astragali that was previously demonstrated to be angiogenic in the zebrafish model. The metabolism of calycosin and accumulation of its metabolites in zebrafish larvae were determined using an LC-MS/MS method. Calycosin showed a slow but steady decrease from the culture medium as well as a steady accumulation in zebrafish larvae. Calycosin underwent major conjugation and minor oxidation in zebrafish larvae. A total of ten calycosin metabolites formed from glucuronidation, glucosylation, sulfation, oxidation or a combination of two of these metabolisms were identified, most of which were reported for the first time. Most metabolites increased steadily in the larvae over 24-h experimental period. The dominant phase II conjugation of calycosin in zebrafish larvae matched well with existing knowledge of isoflavone metabolism in mammalians. The findings shed a light in certain degree of similarity of phase II drug metabolism between zebrafish larvae and mammals and warrant further investigation on feasibility of adopting the zebrafish larvae as a whole-organism model for examining drug metabolism.
Angelica Sinensis Isolate SBD.4: Composition, Gene Expression Profiling, Mechanism of Action and Effect on Wounds, in Rats and Humans
European Journal of Dermatology : EJD. Jan-Feb, 2012 | Pubmed ID: 22146555
This report characterizes an aqueous isolate (SBD.4) of one of the most broadly used Chinese medicinal herbs, Angelica sinensis, from the perspective of its application in skin and wound care. SBD.4 has been chemically defined and was found to increase the strength of healed wounds in retired breeder (older) rats. Furthermore, the mechanism of action of this Angelica sinensis isolate was tested in the zebrafish angiogenesis model, and in human skin substitutes by DNA microarray, revealing a bioactivity profile consistent with skin repair and regeneration. When combined with several types of wound dressings, SBD.4 increased type I collagen production in human dermal fibroblasts, and when formulated in nanosilver hydrocolloid dressing, it was found effective in chronic ulcer management in humans, demonstrating that botanical high-tech wound dressings can be successfully developed to improve the treatment of chronic lesions in humans.
Molecular Medicine Reports. Mar, 2012 | Pubmed ID: 22179585
Astragaloside IV (AS-IV) is a natural product isolated from the Chinese medical herb, Radix Astragali, which has been reported to be a potential candidate for treating diseases associated with abnormal angiogenesis; however, the effect of AS-IV on angiogenesis and its underlying mechanisms are yet to be fully elucidated. In the present study, we investigated the angiogenic effect of AS-IV in vitro using human umbilical vein endothelial cells (HUVECs), and in vivo using zebrafish. AS-IV was found to stimulate the proliferation and migration of HUVECs in an XTT assay and a wound healing migration assay, respectively. Moreover, AS-IV stimulated the invasive ability of HUVECs and significantly increased the mean tube length of HUVECs in Matrigel. AS-IV induced an angiogenic response in HUVECs and enhanced mRNA expression of vascular endothelial growth factor (VEGF) and a VEGF receptor known as kinase‑domain region/fetal liver kinase-1/VEGF receptor 2 (KDR/Flk-1/VEGFR2), as well as activation of Akt as demonstrated by quantitative real-time PCR and Western blot analysis, respectively. The AS-IV-induced proliferation of HUVECs was capable of being suppressed by a KDR inhibitor (SU5416) and an Akt inhibitor (SH-6). AS-IV also rescued blood vessel loss in Tg (fli-1:EGFP) zebrafish. Altogether, our results suggest that AS-IV exerts potential pro-angiogenic effects in vitro and in vivo, and that its pro-angiogenic activity probably involves both VEGF- and Akt-dependent signaling pathways.
Small (Weinheim an Der Bergstrasse, Germany). Mar, 2012 | Pubmed ID: 22213653
The interaction of proteins with ultrasmall gold nanoclusters (Au NCs) is investigated. Upon protein association, the fluorescence of Au NCs is significantly enhanced and, concomitantly, their luminescence lifetime is prolonged. The results stress the importance of investigating the behavior of fluorescent metal NCs in complex biological environment for advancing their bio-nanotechnology applications.
Vascular Cell. 2012 | Pubmed ID: 22357377
Astragali Radix has been used widely for the treatment of cardiovascular and cerebrovascular diseases, and to enhance endurance and stamina in traditional Chinese medicine (TCM) for over 2000 years. The polysaccharide constituents of Astragali Radix (ARP) are considered as one of the major constituents contributing to the multiple pharmacological effects of this medicinal plant. The purpose of the study is to evaluate the vascular regenerative activities of ARPs in a chemically-induced blood vessel loss model in zebrafish.
International Journal of Molecular Sciences. 2012 | Pubmed ID: 22408441
In our previous study, we found that acute anterior uveitis (AAU) could be induced in wild-type mice (C3H/HeN), but it could not be induced in TLR4 gene-deficient mice (C3H/HeJ), we concluded that the translocation of transcription factor nuclear factor-κB (NF-κB) may play an important role. In this study, we examined the concentration of different cytokines in the aqueous humor of C3H/HeN mice and C3H/HeJ mice with the aim of exploring the role of different cytokines in the lipopolysaccharide (LPS) and TLR4-mediated signal transduction in the development of AAU.
Prognostic Significance of MCM7 Expression in the Bronchial Brushings of Patients with Non-small Cell Lung Cancer (NSCLC)
Lung Cancer (Amsterdam, Netherlands). Jul, 2012 | Pubmed ID: 22456526
To identify potential biomarkers for the prognosis of non-small cell lung cancer (NSCLC) patients by using bronchial brushing specimens.
Microwave-assisted Rapid Synthesis of Luminescent Gold Nanoclusters for Sensing Hg2+ in Living Cells Using Fluorescence Imaging
Nanoscale. Jul, 2012 | Pubmed ID: 22460520
A microwave-assisted strategy for synthesizing dihydrolipoic acid (DHLA) capped fluorescent gold nanoclusters (AuNCs) has been developed. Irradiation with microwaves during synthesis enhanced the fluorescence quantum yield (QY) of AuNCs by about five-fold and shortened the reaction time from hours to several minutes. The as-synthesized DHLA-AuNCs possessed bright near-infrared fluorescence (QY: 2.9%), ultrasmall hydrodynamic diameter (3.3 nm), good colloidal stability over the physiologically relevant pH range of 5-10 as well as low cytotoxicity toward HeLa cells. Moreover, these DHLA-AuNCs were capable of sensing Hg(2+) through the specific interaction between Hg(2+) and Au(+) on the surface of AuNCs; the limit of detection (LOD) was 0.5 nM. A potential application in imaging intracellular Hg(2+) in HeLa cells was demonstrated by using spinning disc confocal microscopy.
ANZ Journal of Surgery. Jan-Feb, 2012 | Pubmed ID: 22507490
For proven gastro-oesophageal reflux disease, partial fundoplication is considered as effective as Nissen, but with fewer side effects. The aim of this meta-analysis was to compare the effect of laparoscopic partial fundoplication (LPF) with laparoscopic Nissen fundoplication (LNF).
PLoS Genetics. 2012 | Pubmed ID: 22685420
MicroRNAs (miRNAs) play important roles in normal cellular differentiation and oncogenesis. microRNA93 (mir-93), a member of the mir106b-25 cluster, located in intron 13 of the MCM7 gene, although frequently overexpressed in human malignancies may also function as a tumor suppressor gene. Using a series of breast cancer cell lines representing different stages of differentiation and mouse xenograft models, we demonstrate that mir-93 modulates the fate of breast cancer stem cells (BCSCs) by regulating their proliferation and differentiation states. In "claudin(low)" SUM159 cells, expression of mir-93 induces Mesenchymal-Epithelial Transition (MET) associated with downregulation of TGFβ signaling and downregulates multiple stem cell regulatory genes, including JAK1, STAT3, AKT3, SOX4, EZH1, and HMGA2, resulting in cancer stem cell (CSC) depletion. Enforced expression of mir-93 completely blocks tumor development in mammary fat pads and development of metastases following intracardiac injection in mouse xenografts. The effect of mir-93 on the CSC population is dependent on the cellular differentiation state, with mir-93 expression increasing the CSC population in MCF7 cells that display a more differentiated "luminal" phenotype. mir-93 also regulates the proliferation and differentiation of normal breast stem cells isolated from reduction mammoplasties. These studies demonstrate that miRNAs can regulate the states and fates of normal and malignant mammary stem cells, findings which have important biological and clinical implications.
Journal of Assisted Reproduction and Genetics. Sep, 2012 | Pubmed ID: 22733316
To reevaluate the effect of isolated teratozoospermia on IVF and determine if there was any therapeutic benefit to isolated teratozoospermia by ICSI, since there are no widely accepted criteria for the treatment technique about isolated teratozoospermia.
From Omics to Drug Metabolism and High Content Screen of Natural Product in Zebrafish: a New Model for Discovery of Neuroactive Compound
Evidence-based Complementary and Alternative Medicine : ECAM. 2012 | Pubmed ID: 22919414
The zebrafish (Danio rerio) has recently become a common model in the fields of genetics, environmental science, toxicology, and especially drug screening. Zebrafish has emerged as a biomedically relevant model for in vivo high content drug screening and the simultaneous determination of multiple efficacy parameters, including behaviour, selectivity, and toxicity in the content of the whole organism. A zebrafish behavioural assay has been demonstrated as a novel, rapid, and high-throughput approach to the discovery of neuroactive, psychoactive, and memory-modulating compounds. Recent studies found a functional similarity of drug metabolism systems in zebrafish and mammals, providing a clue with why some compounds are active in zebrafish in vivo but not in vitro, as well as providing grounds for the rationales supporting the use of a zebrafish screen to identify prodrugs. Here, we discuss the advantages of the zebrafish model for evaluating drug metabolism and the mode of pharmacological action with the emerging omics approaches. Why this model is suitable for identifying lead compounds from natural products for therapy of disorders with multifactorial etiopathogenesis and imbalance of angiogenesis, such as Parkinson's disease, epilepsy, cardiotoxicity, cerebral hemorrhage, dyslipidemia, and hyperlipidemia, is addressed.
Journal of Occupational Health. 2012 | Pubmed ID: 23060028
Work stress is an emergent risk in occupational health in China, and its measurement is still a critical issue. The aim of this study was to examine the reliability and validity of a short version of the effort-reward imbalance (ERI) questionnaire in a sample of Chinese workers.
Levofloxacin-containing Triple and Sequential Therapy or Standard Sequential Therapy As the First Line Treatment for Helicobacter Pylori Eradication in China
Helicobacter. Dec, 2012 | Pubmed ID: 23067317
To compare the efficacy and the adverse effects of levofloxacin-containing triple therapy, standard sequential therapy, and levofloxacin-containing sequential therapy as first-line treatment for Helicobacter pylori eradication.
BMC Medical Genomics. Nov, 2012 | Pubmed ID: 23158542
Rectal cancer is one of the most common cancers in the world. Early detection and early therapy are important for the control of death caused by rectal cancer. The present study aims to investigate the genomic alterations in rectal adenoma and carcinoma.
Zhong Xi Yi Jie He Xue Bao = Journal of Chinese Integrative Medicine. Nov, 2012 | Pubmed ID: 23158936
Traditional Chinese medicine (TCM) exhibits a broad range of effects on biological activity that is probably due to interactions of complex chemical constituents with multiple targets in the body. Understanding the active chemical constituents in TCM is very important in providing rationales for the clinical usage of TCM. The zebrafish (Danio rerio) has recently become a popular model in the field of drug screening, specifically emerging as an important vertebrate model for in vivo high-content drug screening of multiple efficacy parameters and whole-organism toxicity. The authors also discussed the advantages of the zebrafish model for evaluating drug metabolism. Zebrafish usage in TCM screening should be a viable approach that helps identify active chemical markers, biological pathways and mechanistic actions of TCM.
Nature Cell Biology. Dec, 2012 | Pubmed ID: 23159929
Although elongation of telomeres is thought to be the prime function of reactivated telomerase in cancers, this activity alone does not account for all of the properties that telomerase reactivation attributes to human cancer cells. Here, we uncover a link between telomerase and NF-κB, a master regulator of inflammation. We observe that while blocking NF-κB signalling can inhibit effects of telomerase overexpression on processes relevant to transformation, increasing NF-κB activity can functionally substitute for reduced telomerase activity. Telomerase directly regulates NF-κB-dependent gene expression by binding to the NF-κB p65 subunit and recruitment to a subset of NF-κB promoters such as those of IL-6 and TNF-α, cytokines that are critical for inflammation and cancer progression. As NF-κB can transcriptionally upregulate telomerase levels, our findings suggest that a feed-forward regulation between them could be the key mechanistic basis for the coexistence of chronic inflammation and sustained telomerase activity in human cancers.
Annual Review of Pathology. Jan, 2013 | Pubmed ID: 22934675
Telomere biology plays a critical and complex role in the initiation and progression of cancer. Although telomere dysfunction resulting from replicative attrition constrains tumor growth by engaging DNA-damage signaling pathways, it can also promote tumorigenesis by causing oncogenic chromosomal rearrangements. Expression of the telomerase enzyme enables telomere-length homeostasis and allows tumor cells to escape the antiproliferative barrier posed by short telomeres. Telomeres and telomerase also function independently of one another. Recent work has suggested that telomerase promotes cell growth through pathways unrelated to telomere maintenance, and a subset of tumors elongate telomeres through telomerase-independent mechanisms. In an effort to exploit the integral link between telomere biology and cancer growth, investigators have developed several telomerase-based therapeutic strategies, which are currently in clinical trials. Here, we broadly review the state of the field with a particular focus on recent developments of interest.
Gold Nanocluster-based Electrochemically Controlled Fluorescence Switch Surface with Prussian Blue As the Electrical Signal Receptor
Chemical Communications (Cambridge, England). Jan, 2013 | Pubmed ID: 23174852
A highly robust electrochemically controlled fluorescence switch based on ultrasmall Au nanoclusters has been designed by the aid of the electrochemical redox reaction of prussian blue.
Nanoscale. Feb, 2013 | Pubmed ID: 23322237
We have studied cellular uptake of ultrasmall fluorescent gold nanoclusters (AuNCs) by HeLa cells by confocal fluorescence microscopy in combination with quantitative image analysis. Water solubilized, lipoic acid-protected AuNCs, which had an overall hydrodynamic diameter of 3.3 nm and emitted fluorescence in the near-infrared region at ∼700 nm, were observed to accumulate on the cell membrane prior to internalization. The internalization mechanisms were analyzed using inhibitors known to interfere with specific pathways. Cellular uptake of AuNCs is energy-dependent and involves multiple mechanisms: clathrin-mediated endocytosis and macropinocytosis appear to play a significant role, whereas the caveolin-mediated pathway contributes only to a lesser extent. Co-labeling of different cell organelles showed that intracellular trafficking of AuNCs mainly follows through endosomal pathways. The AuNCs were ultimately transferred to lysosomes; they were completely excluded from the nucleus even after 24 h.
Inhibition of Atypical Protein Kinase CÎ¹ Induces Apoptosis Through Autophagic Degradation of Î²-catenin in Esophageal Cancer Cells
Molecular Carcinogenesis. Jan, 2013 | Pubmed ID: 23359356
Atypical protein kinase CÎ¹ (PKCÎ¹) has been identified as an oncoprotein in esophageal squamous cell carcinomas. However, the mechanisms underlying the role of PKCÎ¹ in this disease remain unclear. In the present work, we found that inhibition of PKCÎ¹ expression by RNAi induced apoptosis via the down-regulation of Î²-catenin in esophageal cancer cells. Furthermore, we found that PKCÎ¹ regulated Î²-catenin in an autophagy dependent way. Since down-regulation of Î²-catenin induced by knockdown of PKCÎ¹ could be rescued by autophagy inhibition; knockdown of PKCÎ¹ activated autophagy and promoted the recruitment of Î²-catenin into autophagosome. These results suggested that PKCÎ¹ positively regulated Î²-catenin through negatively regulated autophagy and depletion of PKCÎ¹ promoted apoptosis via autophagic degradation of Î²-catenin in esophageal cancer cells. These data provide new insights into PKCÎ¹ signaling in human cancer. Â© 2013 Wiley Periodicals, Inc.
Molecular BioSystems. Jun, 2013 | Pubmed ID: 23549429
Rho kinases (ROCK1 and ROCK2) belong to serine/threonine (Ser/Thr) protein kinase family, and play the central roles in the organization of the actin cytoskeleton. Therefore, Rho kinases have become attractive targets for the treatments of many diseases, such as cancer, renal disease, hypertension, ischemia, and stroke. In order to develop small-molecule inhibitors of ROCK1, molecular docking was utilized to virtually screen two chemical databases and identify molecules that interact with ROCK1. A small set of virtual hits was purchased and submitted to a series of experimental assays. The in vitro enzyme-based and cell-based assays reveal that 12 compounds have good inhibitory activity against ROCK1 in the micro molar regime (IC50 values between about 7 and 28 μM) and antitumor activity against lung cancer, breast cancer or/and myeloma cell lines. The structural analysis shows that two active compounds present novel scaffolds and are potential leads for the development of novel anti-cancer drugs. We then characterized the interaction patterns between ROCK1 and two inhibitors with novel scaffolds by molecular dynamics (MD) simulations and free energy decomposition analysis. In addition, the pharmacological effect of the two ROCK1 inhibitors with novel scaffolds on atorvastatin-induced cerebral hemorrhage was evaluated by using zebrafish model, and one compound candidate is able to prevent atorvastatin-induced cerebral hemorrhage effectively.
Protective Role of Functionalized Single Walled Carbon Nanotubes Enhance Ex Vivo Expansion of Hematopoietic Stem and Progenitor Cells in Human Umbilical Cord Blood
Nanomedicine : Nanotechnology, Biology, and Medicine. Nov, 2013 | Pubmed ID: 23732300
In this study, carboxylic acid functionalized single walled carbon nanotubes (f-SWCNT-COOH) was shown to support the viability and ex vivo expansion of freeze-thawed, non-enriched hematopoietic stem and progenitor cells (HSPC) in human umbilical cord blood-mononucleated cells (UCB-MNC). Our in vitro experiments showed that f-SWCNT-COOH increased the viability of the CD45(+) cells even without cytokine stimulation. It also reduced mitochondrial superoxides and caspase activity in CD45(+) cells. f-SWCNT-COOH drastically reduced the proportions of CD45(-) cells in the non-enriched UCB-MNC. Phenotypic expression analysis and functional colony forming units (CFU) showed significant ex vivo expansion of HSPC, particularly of CD45(+)CD34(+)CD38(-) population and granulocyte-macrophage (GM) colonies, in f-SWCNT-COOH augmented cultures supplemented with basal cytokines. In vivo data suggested that f-SWCNT-COOH expanded UCB-MNC could repopulate immunodeficient mice models with minimal acute or sub-acute symptoms of graft-versus-host disease (GVHD) and f-SWCNT-COOH dependent toxicity.
PTP1B Contributes to Calreticulin-induced Metastatic Phenotypes in Esophageal Squamous Cell Carcinoma
Molecular Cancer Research : MCR. Sep, 2013 | Pubmed ID: 23814025
Calreticulin (CRT) is a Ca(2+)-binding chaperone protein that alters cellular Ca(2+)-homeostasis in the endoplasmic reticulum (ER). Previously it was shown that CRT was overexpressed in esophageal squamous cell carcinoma (ESCC), and elevated CRT expression promoted the migration and invasion of ESCC cells. In the present study, the mechanisms underlying the role of CRT in esophageal carcinoma progression were investigated. Critically, depletion of CRT or protein-tyrosine phosphatase 1B (PTP1B) reduced ESCC cell migration and metastasis to the lung, whereas restoration of PTP1B protein levels rescued cell migration in CRT-silenced cells. Knockdown of CRT decreased PTP1B protein expression by reducing phosphorylation at the Y694 site of STAT5A, whereas knockdown of PTP1B reduced ERK1/2 phosphorylation at T204. Immunohistochemical analysis of CRT and PTP1B expression in ESCC patient tissues was strongly correlated. Importantly, PTP1B expression was associated with poor survival in patients with CRT overexpression. Overall, these data indicate a novel signaling pathway connecting CRT, STAT5A, PTP1B, and ERK1/2 in the regulation of ESCC cell migration.
Frontiers of Medicine. Dec, 2013 | Pubmed ID: 24002746
Esophageal squamous cell carcinoma (ESCC) is one of the most common types of gastrointestinal cancers, and the fourth leading cause of cancer-related deaths in China. Early detection and intervention in time may dramatically increase the survival of the patients by initiating treatment regimens during earlier stages of ESCC or even during precancerous stages. Molecular classification will be useful for subtyping esophageal tumors or precancerous lesions to improve current therapeutics or early intervention of the disease. In this review, we summarize the findings in investigating the molecular alterations and clinical relevance of ESCC.
Consistent and Differential Genetic Aberrations Between Esophageal Dysplasia and Squamous Cell Carcinoma Detected by Array Comparative Genomic Hybridization
Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Nov, 2013 | Pubmed ID: 24009147
Our aim was to identify frequent genomic aberrations in both esophageal squamous cell carcinoma (ESCC) and esophageal dysplasia and to discover important copy number-driving genes and microRNAs (miRNA) in ESCC.
Angewandte Chemie (International Ed. in English). Oct, 2013 | Pubmed ID: 24039076
The "gold standard" for nanothermometry: The application of ultrasmall, near-IR-emitting fluorescent gold nanoclusters (AuNCs) for temperature sensing has been explored. AuNC-based fluorescent nanothermometry features excellent thermal sensitivity and simultaneous temperature sensing and imaging in HeLa cells.
Psychosocial Work Environment and Intention to Leave the Nursing Profession: a Cross-national Prospective Study of Eight Countries
International Journal of Health Services : Planning, Administration, Evaluation. 2013 | Pubmed ID: 24066419
Many countries throughout the world are facing a serious nursing shortage, and retention of nurses also is a challenge. The aim of this study was to compare the predictive contribution of a broad spectrum of psychosocial work factors, including job strain, effort-reward imbalance, and alternative employment opportunity, to the probability of intention to leave the nursing profession. A total of 7,990 registered female nurses working in hospitals in eight countries (Germany, Italy, France, The Netherlands, Belgium, Poland, Slovakia, and China) were included in the one-year prospective study. A standardized questionnaire on job strain, effort-reward imbalance, employment opportunity, and intention to leave the nursing profession was used in the survey. Multilevel logistic regression modeling was used to analyze the data. Results showed that an imbalance between high effort and low reward (in particular, poor promotion prospects) and good employment opportunity at baseline were independently associated with a new intention to leave the nursing profession at follow-up. However, job strain appeared to have relatively less explanatory power. Findings suggest that interventions to improve the psychosocial work environment, especially the reciprocity experienced between effort and reward, may be effective in improving retention of nurses and tackling the international nursing shortage.
Journal of Immunology (Baltimore, Md. : 1950). Dec, 2013 | Pubmed ID: 24184558
Central memory T lymphocytes were reported to develop after acute but not chronic infection, which prompted this feasibility study on generating long-term CD8 T cells ex vivo, by applying a culture condition that simulates an acute infection. During 35 d of culture, naive T cells (CD45RA(+), CD127(+), CCR7(+), CD62L(+), CXCR3(+)) first developed into effector T cells (CD45RA(+/-), CD127(+/-), CCR7(+/-), CD62L(+), CXCR3(+)), followed by three intermediate stages: intermediate T cells 1 (CD45RO(+), CD127(+/-), CCR7(+), CD62L(+), CXCR3(+)), intermediate T cells 2 (CD45RO(+), CD127(-), CCR7(-), CD62L(+), CXCR3(+)), and intermediate T cells 3 (CD45RO(+/-), CD127(+), CCR7(+), CD62L(-), CXCR3(+)) before reverting to stable CD45RA(+) central memory T cells (CD45RA(+), CD127(+), CCR7(+), CD62L(+), CXCR3(+)). If both anti-CD3 and the inflammatory milieu persisted beyond day 10, intermediate T cells 2 gradually developed into effector memory T cells (CD45RO(+), CD127(-), CCR7(-), CD62L(-), CXCR3(+)). Furthermore, intermediate T cells 2 or effector memory T cells, when cultured in persistent inflammatory cytokines devoid of anti-CD3, were converted to central memory T cells (CD45RO(+), CCR7(+), CD62L(+)). Overall, these results support ex vivo memory-like T lymphocyte production and favor a developmental pathway including both divergent and linear relationships.
Applied Optics. Nov, 2013 | Pubmed ID: 24216668
An array of passive silicon-on-insulator optical devices is laid out in repeating patterns on four foundry-fabricated wafers. The physical and optical characterization of these microrings, racetrack resonators, and directional couplers are found to exhibit significant variation in optical response. A device-heating experiment carried out on a number of different devices demonstrates that thermal effects are independent of the device's location on the wafer. An analysis of the variation of the optical responses of the room-temperature devices is used to determine the process variation. We find that if we form successive arrays of the values of a quantity of interest (the peak wavelength of a transfer function) at a single device at some point on the wafer, and then increase the size of the array by including the values of the devices at ever greater distances from the original, then the variance of the values of the successive arrays increases linearly with the linear extent of the sample. That is, the process variation exhibits "random walk" pattern with spatial extent. We express the process variation in units of variance per length and find that our measured values agree with others in the literature; that is, the process variation is approximately 1 nm2/cm.
[Overexpression of P-Stat3 and Mcl-1, and Their Correlation with Differentiation and Apoptotic Resistance in Esophageal Squamous Cell Carcinoma]
Zhonghua Zhong Liu Za Zhi [Chinese Journal of Oncology]. Aug, 2013 | Pubmed ID: 24314214
To detect the expression of phosphorylated-signal transducer and activator of transcription 3 (p-Stat3) and myeloid leukemia-1 (Mcl-1) as well as their correlation, and to investigate the functional role of Stat3 and Mcl-1 in the pathogenesis of esophageal squamous cell carcinoma (ESCC).
Social Psychiatry and Psychiatric Epidemiology. Feb, 2014 | Pubmed ID: 23811953
Suicide is one of the leading causes of death during adolescence worldwide. This study, using a sample of Chinese adolescents, examines associations of a stressful psychosocial school environment with suicidal ideation, which were rarely investigated so far.
Cdk1 Regulates the Temporal Recruitment of Telomerase and Cdc13-Stn1-Ten1 Complex for Telomere Replication
Molecular and Cellular Biology. Jan, 2014 | Pubmed ID: 24164896
In budding yeast (Saccharomyces cerevisiae), the cell cycle-dependent telomere elongation by telomerase is controlled by the cyclin-dependent kinase 1 (Cdk1). The telomere length homeostasis is balanced between telomerase-unextendable and telomerase-extendable states that both require Cdc13. The recruitment of telomerase complex by Cdc13 promotes telomere elongation, while the formation of Cdc13-Stn1-Ten1 (CST) complex at the telomere blocks telomere elongation by telomerase. However, the cellular signaling that regulates the timing of the telomerase-extendable and telomerase-unextendable states is largely unknown. Phosphorylation of Cdc13 by Cdk1 promotes the interaction between Cdc13 and Est1 and hence telomere elongation. Here, we show that Cdk1 also phosphorylates Stn1 at threonine 223 and serine 250 both in vitro and in vivo, and these phosphorylation events are essential for the stability of the CST complexes at the telomeres. By controlling the timing of Cdc13 and Stn1 phosphorylations during cell cycle progression, Cdk1 regulates the temporal recruitment of telomerase complexes and CST complexes to the telomeres to facilitate telomere maintenance.
Impact of Protein Modification on the Protein Corona on Nanoparticles and Nanoparticle-cell Interactions
ACS Nano. Jan, 2014 | Pubmed ID: 24377255
Recent studies have firmly established that cellular uptake of nanoparticles is strongly affected by the presence and the physicochemical properties of a protein adsorption layer around these nanoparticles. Here, we have modified human serum albumin (HSA), a serum protein often used in model studies of protein adsorption onto nanoparticles, to alter its surface charge distribution and investigated the consequences for protein corona formation around small (radius ∼5 nm), dihydrolipoic acid-coated quantum dots (DHLA-QDs) by using fluorescence correlation spectroscopy. HSA modified by succinic anhydride (HSAsuc) to generate additional carboxyl groups on the protein surface showed a 3-fold decreased binding affinity toward the nanoparticles. A 1000-fold enhanced affinity was observed for HSA modified by ethylenediamine (HSAam) to increase the number of amino functions on the protein surface. Remarkably, HSAsuc formed a much thicker protein adsorption layer (8.1 nm) than native HSA (3.3 nm), indicating that it binds in a distinctly different orientation on the nanoparticle, whereas the HSAam corona (4.6 nm) is only slightly thicker. Notably, protein binding to DHLA-QDs was found to be entirely reversible, independent of the modification. We have also measured the extent and kinetics of internalization of these nanoparticles without and with adsorbed native and modified HSA by HeLa cells. Pronounced variations were observed, indicating that even small physicochemical changes of the protein corona may affect biological responses.
Journal of Nanobiotechnology. Feb, 2014 | Pubmed ID: 24491160
With the rapid advancement of nanoscience and nanotechnology, detailed knowledge of interactions between engineered nanomaterials and cells, tissues and organisms has become increasingly important, especially in regard to possible hazards to human health. This review intends to give an overview of current research on nano-bio interactions, with a focus on the effects of NP size on their interactions with live cells. We summarize common techniques to characterize NP size, highlight recent work on the impact of NP size on active and passive cellular internalization and intracellular localization. Cytotoxic effects are also discussed.
Breast Cancer Stem Cells Transition Between Epithelial and Mesenchymal States Reflective of Their Normal Counterparts
Stem Cell Reports. Jan, 2014 | Pubmed ID: 24511467
Previous studies have suggested that breast cancer stem cells (BCSCs) mediate metastasis, are resistant to radiation and chemotherapy, and contribute to relapse. Although several BCSC markers have been described, it is unclear whether these markers identify the same or independent BCSCs. Here, we show that BCSCs exist in distinct mesenchymal-like (epithelial-mesenchymal transition [EMT]) and epithelial-like (mesenchymal-epithelial transition [MET]) states. Mesenchymal-like BCSCs characterized as CD24(-)CD44(+) are primarily quiescent and localized at the tumor invasive front, whereas epithelial-like BCSCs express aldehyde dehydrogenase (ALDH), are proliferative, and are located more centrally. The gene-expression profiles of mesenchymal-like and epithelial-like BCSCs are remarkably similar across different molecular subtypes of breast cancer, and resemble those of distinct basal and luminal stem cells found in the normal breast. We propose that the plasticity of BCSCs that allows them to transition between EMT- and MET-like states endows these cells with the capacity for tissue invasion, dissemination, and growth at metastatic sites.
Pathology Oncology Research : POR. Apr, 2014 | Pubmed ID: 24531888
Based on our previous experiments, this study is to further investigate the functional significance of miR-181a and its target gene in gastric cancer. Expression of miR-181a was detected by qRT-PCR in three normal gastric tissues and three human gastric cancer cell lines (SGC-7901, MGC-803, and BGC-823 cells). After transfection with miR-181a inhibitor, proliferation, apoptosis, migration, and invasion of the SGC-7901 cells were evaluated. Ataxia-telangiectasia mutation (ATM) was predicted as a target gene of miR-181a with bioinformatics analysis, and was verified by lucifersae reporter assay. Expression of ATM protein in HEK293T cells and tissues was measured by Western Blot. Expression of ATM mRNA in HEK293T cells was measured by RT-PCR. Compared with three non-tumour tissues, the expression of miR-181a in three gastric cancer cells was significantly increased by 26.68, 14.83 and 14.96 folds; Compared with Negative Control(NC) and blank groups, transfection of miR-181a inhibitor led to inhibition of SGC7901 cell proliferation, invasion, and migration as well as promotion of apoptosis. A luciferase reporter assay demonstrated that ATM was a direct target of miR-181a, miR-181a mimics transfection down regulated ATM mRNA and protein expression. There was inverse correlation between miR-181a and ATM protein expression in gastric cancer and normal gastric tissues. Our study demonstrates that over-expression of miR-181a might be involved in development of gastric cancer by promoting proliferation and inhibiting apoptosis probably through directly targeting ATM. miR-181a modulation may be a potential strategy for the development of miRNA-based therapy of gastric cancer.
Applied Optics. Mar, 2014 | Pubmed ID: 24663369
Three sets of devices were simulated, designed, and laid out for fabrication in the EuroPractice shuttle program and then measured in-house after fabrication. A combination of analytical and numerical modeling is used to extract the dispersion curves that define the effective index of refraction as a function of wavelength for three different classes of silicon photonic devices, namely, micro-ring resonators, racetrack resonators, and directional couplers. The results of this phenomenological study are made plausible by the linearity of the extracted dispersion curves with wavelength over the wavelength regime of interest (S and C bands) and the use of the determined effective indices to reconstruct the measured transmission as a function of wavelength curves in close agreement with experiment. The extracted effective indices can be used to place limits on the actual fabricated values of waveguide widths, thicknesses, radii of curvature, and coupling gaps.
Nature Genetics. May, 2014 | Pubmed ID: 24686850
Esophageal squamous cell carcinoma (ESCC) is prevalent worldwide and particularly common in certain regions of Asia. Here we report the whole-exome or targeted deep sequencing of 139 paired ESCC cases, and analysis of somatic copy number variations (SCNV) of over 180 ESCCs. We identified previously uncharacterized mutated genes such as FAT1, FAT2, ZNF750 and KMT2D, in addition to those already known (TP53, PIK3CA and NOTCH1). Further SCNV evaluation, immunohistochemistry and biological analysis suggested their functional relevance in ESCC. Notably, RTK-MAPK-PI3K pathways, cell cycle and epigenetic regulation are frequently dysregulated by multiple molecular mechanisms in this cancer. Our approaches also uncovered many druggable candidates, and XPO1 was further explored as a therapeutic target because it showed both gene mutation and protein overexpression. Our integrated study unmasks a number of novel genetic lesions in ESCC and provides an important molecular foundation for understanding esophageal tumors and developing therapeutic targets.
Network Based Analyses of Gene Expression Profile of LCN2 Overexpression in Esophageal Squamous Cell Carcinoma
Scientific Reports. Jun, 2014 | Pubmed ID: 24954627
LCN2 (lipocalin 2) is a member of the lipocalin family of proteins that transport small, hydrophobic ligands. LCN2 is elevated in various cancers including esophageal squamous cell carcinoma (ESCC). In this study, LCN2 was overexpressed in the EC109 ESCC cell line and we applied integrated analyses of the gene expression data to identify protein-protein interactions (PPI) network to enhance our understanding of the role of LCN2 in ESCC. Through further mining of PPI sub-networks, hundreds of differentially expressed genes (DEGs) were identified to interact with thousands of other proteins. Subcellular localization analyses found the DEGs and their directly or indirectly interacting proteins distributed in multiple layers, which was applied to analyze the possible paths between two DEGs. Gene Ontology annotation generated a functional annotation map and found hundreds of significant terms, especially those associated with the known and potential roles of LCN2 protein. The algorithm of Random Walk with Restart was applied to prioritize the DEGs and identified several cancer-related DEGs ranked closest to LCN2 protein. These analyses based on PPI network have greatly expanded our understanding of the mRNA expression profile of LCN2 overexpression for future examination of the roles and mechanisms of LCN2.
Discovery of a Benzofuran Derivative (MBPTA) As a Novel ROCK Inhibitor That Protects Against MPP⁺-induced Oxidative Stress and Cell Death in SH-SY5Y Cells
Free Radical Biology & Medicine. Sep, 2014 | Pubmed ID: 24973649
Parkinson disease (PD) is a neurodegenerative disease with multifactorial etiopathogenesis. The discovery of drug candidates that act on new targets of PD is required to address the varied pathological aspects and modify the disease process. In this study, a small compound, 2-(5-methyl-1-benzofuran-3-yl)-N-(5-propylsulfanyl-1,3,4-thiadiazol-2-yl) acetamide (MBPTA) was identified as a novel Rho-associated protein kinase inhibitor with significant protective effects against 1-methyl-4-phenylpyridinium ion (MPP(+))-induced damage in SH-SY5Y neuroblastoma cells. Further investigation showed that pretreatment of SH-SY5Y cells with MBPTA significantly suppressed MPP(+)-induced cell death by restoring abnormal changes in nuclear morphology, mitochondrial membrane potential, and numerous apoptotic regulators. MBPTA was able to inhibit MPP(+)-induced reactive oxygen species (ROS)/NO generation, overexpression of inducible NO synthase, and activation of NF-κB, indicating the critical role of MBPTA in regulating ROS/NO-mediated cell death. Furthermore, MBPTA was shown to activate PI3K/Akt survival signaling, and its cytoprotective effect was abolished by PI3K and Akt inhibitors. The structural comparison of a series of MBPTA analogs revealed that the benzofuran moiety probably plays a crucial role in the anti-oxidative stress action. Taken together, these results suggest that MBPTA protects against MPP(+)-induced apoptosis in a neuronal cell line through inhibition of ROS/NO generation and activation of PI3K/Akt signaling.
In Vivo Angiogenesis Screening and Mechanism of Action of Novel Tanshinone Derivatives Produced by One-pot Combinatorial Modification of Natural Tanshinone Mixture from Salvia Miltiorrhiza
PloS One. 2014 | Pubmed ID: 24992590
Natural products present in low quantity in herb medicines constitute an important source of chemical diversity. However, the isolation of sufficient amounts of these low abundant constituents for structural modification has been a challenge for several decades and subsequently halts research on the utilization of this important source of chemical entities for drug discovery and development. And, pro-angiogenic therapies are being explored as options to treat cardio-cerebral vascular diseases and wound healing recently. The present study investigates the pro-angiogenic potential of tanshinone derivatives produced by one-pot synthesis using zebrafish model.
Cancer Cytopathology. Nov, 2014 | Pubmed ID: 25045014
To date, no robust biomarkers have been available in clinical practice that can provide an early diagnostic evaluation of lung cancer. The objective of this study was to identify potential biomarkers for the early detection of lung cancer using bronchial brushing specimens.
Nanosuspension Development of Scutellarein As an Active and Rapid Orally Absorbed Precursor of Its BCS Class IV Glycoside Scutellarin
Journal of Pharmaceutical Sciences. Nov, 2014 | Pubmed ID: 25187229
This work addressed solubility and membrane permeability problems of Biopharmaceutics Classification System (BCS) Class IV glycoside scutellarin (SG) by developing a nanosuspension of its aglycone scutellarein (S) as a precursor. An S nanosuspension containing poloxamer 188 was prepared using antisolvent precipitation where hydroxypropyl-β-cyclodextrin was utilized as a lyophilizing protectant. Particle size and polydispersity index after redispersion were 342.6 ± 18.2 and 0.32 ± 0.06 nm, respectively. The dissolution rate of the S nanosuspension was superior compared with the physical mixture. No free S, but SG and SG's isomer were detected in plasma following oral delivery of SG or S, S nanosuspension or physical mixture of S. The Cmax values of SG after dosing with the S nanosuspension were 12.0, 8.0, and 4.5-fold higher than the SG, S, or physical mixture, respectively. The Tmax and mean residence time (MRTlast ) of SG after dosing with the S nanosuspension were significantly shorter than S and SG. Treatments with SG, S, or S nanosuspensions reduced the hemorrhage rate in a zebrafish model, but the S nanosuspension exhibited the strongest rescue effect. This study highlights a new strategy to circumvent BCS Class IV flavonoid glycosides using a formulation of their aglycone as a precursor to accelerate oral absorption and improve bioactivity.
Cancer Research. Nov, 2014 | Pubmed ID: 25217527
miRNAs are essential for self-renewal and differentiation of normal and malignant stem cells by regulating the expression of key stem cell regulatory genes. Here, we report evidence implicating the miR100 in self-renewal of cancer stem-like cells (CSC). We found that miR100 expression levels relate to the cellular differentiation state, with lowest expression in cells displaying stem cell markers. Utilizing a tetracycline-inducible lentivirus to elevate expression of miR100 in human cells, we found that increasing miR100 levels decreased the production of breast CSCs. This effect was correlated with an inhibition of cancer cell proliferation in vitro and in mouse tumor xenografts due to attenuated expression of the CSC regulatory genes SMARCA5, SMARCD1, and BMPR2. Furthermore, miR100 induction in breast CSCs immediately upon their orthotopic implantation or intracardiac injection completely blocked tumor growth and metastasis formation. Clinically, we observed a significant association between miR100 expression in breast cancer specimens and patient survival. Our results suggest that miR100 is required to direct CSC self-renewal and differentiation.
Calreticulin Promotes Migration and Invasion of Esophageal Cancer Cells by Upregulating Neuropilin-1 Expression Via STAT5A
Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Dec, 2014 | Pubmed ID: 25231404
We previously revealed that the calreticulin (CRT) gene is a candidate oncogene promoting cell migration and invasion and that neuropilin-1 (NRP1) is a possible effector downstream of CRT in esophageal squamous carcinoma cells. This study aims to explore the mechanisms underlying the migration and invasion of esophageal cancer cells regulated by CRT through NRP1.
VEGFR Tyrosine Kinase Inhibitor II (VRI) Induced Vascular Insufficiency in Zebrafish As a Model for Studying Vascular Toxicity and Vascular Preservation
Toxicology and Applied Pharmacology. Nov, 2014 | Pubmed ID: 25234792
In ischemic disorders such as chronic wounds and myocardial ischemia, there is inadequate tissue perfusion due to vascular insufficiency. Besides, it has been observed that prolonged use of anti-angiogenic agents in cancer therapy produces cardiovascular toxicity caused by impaired vessel integrity and regeneration. In the present study, we used VEGFR tyrosine kinase inhibitor II (VRI) to chemically induce vascular insufficiency in zebrafish in vivo and human umbilical vein endothelial cells (HUVEC) in vitro to further study the mechanisms of vascular morphogenesis in these pathological conditions. We also explored the possibility of treating vascular insufficiency by enhancing vascular regeneration and repair with pharmacological intervention. We observed that pretreatment of VRI induced blood vessel loss in developing zebrafish by inhibiting angiogenesis and increasing endothelial cell apoptosis, accompanied by down-regulation of kdr, kdrl and flt-1 genes expression. The VRI-induced blood vessel loss in zebrafish could be restored by post-treatment of calycosin, a cardiovascular protective isoflavone. Similarly, VRI induced cytotoxicity and apoptosis in HUVEC which could be rescued by calycosin post-treatment. Further investigation of the underlying mechanisms showed that the PI3K/AKT/Bad cell survival pathway was a main contributor of the vascular regenerative effect of calycosin. These findings indicated that the cardiovascular toxicity in anti-angiogenic therapy was mainly caused by insufficient endothelial cell survival, suggesting its essential role in vascular integrity, repair and regeneration. In addition, we showed that VRI-induced blood vessel loss in zebrafish represented a simple and effective in vivo model for studying vascular insufficiency and evaluating cancer drug vascular toxicities.
PloS One. 2014 | Pubmed ID: 25337715
Esophageal squamous cell carcinoma (ESCC) is a common cancer with poor prognosis. In order to identify useful biomarkers for accurately classifying prognostic risks for ESCC patients, we examined the expression of six proteins by immunohistochemistry (IHC) in 590 paraffin-embedded ESCC samples. The candidate proteins include p53, EGFR, c-KIT, TIMP1 and PI3K-p110α reported to be altered in ESCC tissues as well as another important component of PI3K, PI3K-p85α. Of the six proteins tested, p53, EGFR, c-KIT, TIMP1 and PI3K-p85α were detected with high expression in 43.0%, 36.6%, 55.9%, 70.7% and 57.1% of tumors, respectively. Significant associations were found between high expression of PI3K-p85α, EGFR and p53 and poor prognosis (P = 0.00111; 0.00001; 0.00426). Applying these three proteins as an IHC panel could divide patients into different subgroups (P<0.000001). Multivariate cox regression analysis indicated that the three-protein panel was an independent prognostic factor with very high statistical significance (HR = 2.090, 95% CI: 1.621-2.696, P = 0.00000001). The data suggest that the three-protein panel of PI3K-p85α, EGFR and p53 is an important candidate biomarker for the prognosis of patients with ESCC.
Drug Design, Development and Therapy. 2014 | Pubmed ID: 25525333
Multidrug resistance (MDR) in tumors renders many currently available chemotherapeutic drugs ineffective. Research in nanobiotechnology-based therapeutic alternatives has provided innovative and promising strategies to overcome MDR. The aim of this study was to investigate whether the new strategy of a co-loaded reversal agent and chemotherapeutic drug with shortened carbon nanotubes (CNTs) would show useful effects on the real-time reversal of tumor MDR. CNTs were cut and purified via ultrasonication and oxidative acid treatment to optimize their length for drug-delivery vehicles, then verapamil (Ver) and doxorubicin (Dox) were co-loaded on shortened CNTs (denoted as Ver/Dox/shortened CNTs), which acted as a drug delivery system. The multidrug resistant leukemia K562/A02 cells were treated with the denoted Ver/Dox/shortened CNTs. The real-time reversal of tumor MDR were evaluated by flow cytometer, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, acridine orange/ethidium bromide staining, and Western blot analysis. In the same MDR tumor cells the new strategy of a co-loaded reversal agent and chemotherapeutic drug with CNTs could inhibit the function of P-glycoprotein in real-time by Ver as reversal agent, significantly increase the uptake of Dox, enhance the sensitivity of the MDR cancer cells to the chemotherapeutic agent, and induce apoptosis. It was therefore concluded that a co-loaded reversal agent and chemotherapeutic drug with shortened CNTs could have real-time reversal ability of MDR in tumors, which could represent a promising approach in cancer therapy.
Effects of Surface Functionalization on the Adsorption of Human Serum Albumin Onto Nanoparticles - a Fluorescence Correlation Spectroscopy Study
Beilstein Journal of Nanotechnology. 2014 | Pubmed ID: 25551031
By using fluorescence correlation spectroscopy (FCS), we have studied the adsorption of human serum albumin (HSA) onto Fe-Pt nanoparticles (NPs, 6 nm radius), CdSe/ZnS quantum dots (QDs, 5 nm radius) and Au and Ag nanoclusters (1-4 nm radius), which are enshrouded by various water-solubilizing surface layers exposing different chemical functional groups (carboxyl, amino and both), thereby endowing the NPs with different surface charges. We have also measured the effects of modified surface functionalizations on the protein via succinylation and amination. A step-wise increase in hydrodynamic radius with protein concentration was always observed, revealing formation of protein monolayers coating the NPs, independent of their surface charge. The differences in the thickness of the protein corona were rationalized in terms of the different orientations in which HSA adsorbs onto the NPs. The midpoints of the binding transition, which quantifies the affinity of HSA toward the NP, were observed to differ by almost four orders of magnitude. These variations can be understood in terms of specific Coulombic interactions between the proteins and the NP surfaces.
Nanoparticle Interactions with Live Cells: Quantitative Fluorescence Microscopy of Nanoparticle Size Effects
Beilstein Journal of Nanotechnology. 2014 | Pubmed ID: 25551067
Engineered nanomaterials are known to enter human cells, often via active endocytosis. Mechanistic details of the interactions between nanoparticles (NPs) with cells are still not well enough understood. NP size is a key parameter that controls the endocytic mechanism and affects the cellular uptake yield. Therefore, we have systematically analyzed the cellular uptake of fluorescent NPs in the size range of 3.3-100 nm (diameter) by live cells. By using spinning disk confocal microscopy in combination with quantitative image analysis, we studied the time courses of NP association with the cell membrane and subsequent internalization. NPs with diameters of less than 10 nm were observed to accumulate at the plasma membrane before being internalized by the cells. In contrast, larger NPs (100 nm) were directly internalized without prior accumulation at the plasma membrane, regardless of their surface charges. We attribute this distinct size dependence to the requirement of a sufficiently strong local interaction of the NPs with the endocytic machinery in order to trigger the subsequent internalization.
[Exploration and Analysis of the Thought of Medical Education in the Shanghai New Chinese Medical College]
Zhonghua Yi Shi Za Zhi (Beijing, China : 1980). Nov, 2014 | Pubmed ID: 25620358
Shanghai New Chinese Medical College set up by Zhu Nanshan and his sons, Zhu Xiaonan and Zhu Hegao, was a medical college of traditional Chinese medicine (TCM) with the most innovative spirit in modern time. Its affiliated research institute held the principle of "realizing the scientific truth of TCM, training TCM advanced talents", marking the beginning of the pioneering of "scientific TCM". The educational plan, clinical research and academic organization based on "carrying forward the quintessence of Chinese culture, absorbing and digesting the new knowledge" showed a certain influence at home and abroad. The College advocated the combination of communicating with famous physicians and the study of theory, cultivation of students' organization and academic society, launching of journals, and organizing students' research associations was aiming at the satisfaction of the social needs and teaching orientation. Its running experience provided useful reference for modern TCM medical education.
Overexpression of DNAJB6 Promotes Colorectal Cancer Cell Invasion Through an IQGAP1/ERK-dependent Signaling Pathway
Molecular Carcinogenesis. Oct, 2015 | Pubmed ID: 25044025
DNAJB6 is a member of the heat shock protein 40 (Hsp40) family. We here investigated the clinical correlation and biological role of DNAJB6 overexpression in colorectal cancer (CRC). The expression of DNAJB6 protein was examined in 200 cases of colorectal adenocarcinomas by immunohistochemistry (IHC) technology. Gene transfection and RNA interference were performed to determine the effect of DNAJB6 expression on the invasion of CRC cells and to explore the underlying molecular mechanisms in vitro and in vivo. Overexpression of DNAJB6 was found in 39% (78/200) of the CRC tissues, especially in tumors at pT4 as compared with at pT1-3 (P = 0.02). A Kaplan-Meier survival analysis revealed a correlation between DNAJB6 expression and overall survival (OS) times (P = 0.003). Multivariate analysis confirmed that DNAJB6 overexpression was an independent prognostic factor for CRC (P = 0.002). RNA interference-mediated silencing of the DNAJB6 gene inhibited the invasion of CRC cells in vitro were accompanied by a significant reduction in the protein levels of IQ-domain GTPase-activating protein 1 (IQGAP1) and phosphorylated ERK (pERK). An in vivo assay showed that inhibition of DNAJB6 expression decreased the lung metastases of CRC cells. IHC analysis of serial sections showed that there was a positive correlation between DNAJB6 and IQGAP1 expression in primary CRC tissues (P = 0.013). The data suggest that DNAJB6 plays an important oncogenic role in CRC cell invasion by up-regulating IQGAP1 and activating the ERK signaling pathway and that DNAJB6 may be used as a prognostic marker for CRC.
Recent Advances in Structure-based Drug Design and Virtual Screening of VEGFR Tyrosine Kinase Inhibitors
Methods (San Diego, Calif.). Jan, 2015 | Pubmed ID: 25239735
During the past decade, developments in computational processing and X-ray crystallography have allowed virtual screening become integrated into drug discovery campaigns. This review focuses on the recent advancements in the drug discovery of VEGFR2 tyrosine kinase inhibitors (VEGFR2 TKIs) by using in silico methodologies. An introduction for the methodology framework of pharmacophore modeling, molecular docking and structure-based design are provided. We discuss the recent studies on the structures of VEGFR2 protein kinase in different binding modes, and the insights on molecular interactions gained from knowledge of the co-crystal structures complex with structurally diverse VEGFR2 inhibitors. We provide some aspects of model construction and molecular docking techniques. Several representative examples of successful applications on VEGFR2 virtual screening for hit discovery, lead optimization and structure-based design are also presented.
Molecular Neurobiology. Dec, 2015 | Pubmed ID: 25344318
Astrocytes play an important role in the pathogenesis of glaucoma. Abnormal activation and/or proliferation of astrocytes, termed astrogliosis, have been observed during optic nerve degeneration. Our previous study identified signal transducer and activator of transcription 3 (STAT3) signaling as an important regulator of astrogliosis in the optic nerve in a rat transient ischemia/reperfusion model. In this study, we used pharmacological inhibition of STAT3 activation in the same model to assess whether it could attenuate reactive astrogliosis and to observe its influence on optic nerve damage and retinal ganglion cell (RGC) damage. Our findings show that retrobulbar inhibition of STAT3 in optic nerve head astrocytes leads to (a) increased nerve fiber bundle survival in the optic nerve, (b) increased nerve fiber bundle and RGC survival in the retina, (c) decreased astrocyte reactivation in the optic nerve (d) decreased remodeling of astrocytes in the optic nerve, and (e) no influence of astrocyte reactivation inside the retina. Taken together, the Janus kinase/STAT3 pathway contributes to astrocyte reactivation in the optic nerve, which plays a pivotal role in neurodegeneration after transient ischemia/reperfusion in vivo. Inhibition of this pathway provides a potential therapeutic strategy for the treatment of glaucomatous neuropathy, and could extend to other neurodegenerative diseases.
Basal Flt1 Tyrosine Kinase Activity is a Positive Regulator of Endothelial Survival and Vascularization During Zebrafish Embryogenesis
Biochimica Et Biophysica Acta. Feb, 2015 | Pubmed ID: 25450186
The role of Kdr (VEGFR-2/Flk-1) in vascular formation has been well described, but the role of Flt1 (VEGFR-1) is not well studied and is generally considered as a decoy receptor for trapping VEGF.
Gene. Feb, 2015 | Pubmed ID: 25497831
The purpose of this study was to assess the protective effect of low molecular weight heparin (LMWH) on acute lung injury (ALI) in rats induced by sepsis. Rat ALI model was reproduced by cecal ligation and puncture (CLP). All rats were randomly divided into three groups (n=50): control group (A), ALI group (B), and LMWH-treated group (C). Group A received a sham operation and the other groups underwent CLP operation. Groups A and B accepted intraperitoneal injection (i.p.) of normal saline (NS) at a dose of 2.0 ml kg(-1) and ceftriaxone (30 mg kg(-1)), group C was intraperitoneally injected with additional LMWH (150 U kg(-1)) except saline and ceftriaxone. Blood was collected and lung tissue was harvested at the designated time points for analysis. The lung specimens were harvested for morphological studies, immunohistochemistry examination. Lung tissue edema was evaluated by tissue water content. The levels of lung tissue myeloperoxidase (MPO) were determined. Meanwhile, the nuclear factor-kappa B (NF-κB) activation, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) levels, high mobility group box 1 (HMGB1) and intercellular adhesion molecule-1 (ICAM-1) protein levels in the lung were studied. There was a significant difference in each index between groups A and B (P<0.05). Treatment with LMWH significantly decreased the expression of TNF-α, IL-1β, HMGB1 and ICAM-1 in the lungs of ALI rats. Similarly, treatment with LMWH dramatically diminished sepsis-induced neutrophil sequestration and markedly reduced the enhanced lung permeability. In the present study, LMWH administration inhibited the nuclear translocation of NF-κB in the lungs. These data suggest that LMWH attenuates inflammation and ameliorates lung pathology in CLP-induced sepsis in a rat model.
Expansion and Homing of Umbilical Cord Blood Hematopoietic Stem and Progenitor Cells for Clinical Transplantation
Biology of Blood and Marrow Transplantation : Journal of the American Society for Blood and Marrow Transplantation. Jun, 2015 | Pubmed ID: 25555449
The successful expansion of hematopoietic stem and progenitor cells (HSPCs) from umbilical cord blood (UCB) for transplantation could revolutionize clinical practice by improving transplantation-related outcomes and making available UCB units that have suboptimal cell doses for transplantation. New cytokine combinations appear able to promote HSPC growth with minimal differentiation into mature precursors and new agents, such as insulin-like growth factor-binding protein 2, are being used in clinical trials. Molecules that simulate the HSPC niche, such as Notch ligand, have also shown promise. Further improvements have been made with the use of mesenchymal stromal cells, which have made possible UCB expansion without a potentially deleterious prior CD34/CD133 cell selection step. Chemical molecules, such as copper chelators, nicotinamide, and aryl hydrocarbon antagonists, have shown excellent outcomes in clinical studies. The use of bioreactors could further add to HSPC studies in future. Drugs that could improve HSPC homing also appear to have potential in improving engraftment times in UCB transplantation. Technologies to expand HSPC from UCB and to enhance the homing of these cells appear to have attained the goal of accelerating hematopoietic recovery. Further discoveries and clinical studies are likely to make the goal of true HSPC expansion a reality for many applications in future.
Effort-reward Imbalance at Work Increases the Risk of the Metabolic Syndrome: a Prospective Study in Chinese University Staff
International Journal of Cardiology. Mar, 2015 | Pubmed ID: 25594932
Psychosocial Work Characteristics and Needle Stick and Sharps Injuries Among Nurses in China: a Prospective Study
International Archives of Occupational and Environmental Health. Oct, 2015 | Pubmed ID: 25605612
Psychosocial work characteristics may be associated with needle stick and sharps injuries (NSIs) among nurses. The current evidence is, however, sparse, inconclusive, and mainly limited to cross-sectional investigations. We aimed to contribute prospective data.
Tumour Biology : the Journal of the International Society for Oncodevelopmental Biology and Medicine. Jun, 2015 | Pubmed ID: 25631750
Lung cancer is the leading cause of cancer-related death worldwide. Transforming growth factor-β receptor II (TGF-βRII) plays an important role in the regulation of proliferation and progression in cancer. Statins have been documented to exhibit anticancer and cancer chemopreventive properties. However, the effects and mechanisms of simvastatin on the development of lung cancer are still unclear. In the present study, quiescent A549 cells were treated in vitro with fetal bovine serum (FBS) in the presence or absence of simvastatin. MTT, Western blot, and real-time qPCR were used to detect cell viability, activation of ERK, and expression of TGF-βRII at the protein and RNA level. Our results demonstrated that simvastatin inhibited activation of ERK, downregulated expression of TGF-βRII, and suppressed A549 cell proliferation. Furthermore, the effects of simvastatin can be reversed by farnesyl pyrophosphate (FPP). Therefore, these results suggest that simvastatin may inhibit A549 cell proliferation and downregulate TGF-βRII expression by inhibiting activation of ERK. Our findings may advance the current understanding of the effects of simvastatin on cancer progression and contribute to the study of cancer treatment.
Role of MicroRNA221 in Regulating Normal Mammary Epithelial Hierarchy and Breast Cancer Stem-like Cells
Oncotarget. Feb, 2015 | Pubmed ID: 25686829
Increasing evidence suggests that lineage specific subpopulations and stem-like cells exist in normal and malignant breast tissues. Epigenetic mechanisms maintaining this hierarchical homeostasis remain to be investigated. In this study, we found the level of microRNA221 (miR-221) was higher in stem-like and myoepithelial cells than in luminal cells isolated from normal and malignant breast tissue. In normal breast cells, over-expression of miR-221 generated more myoepithelial cells whereas knock-down of miR-221 increased luminal cells. Over-expression of miR-221 stimulated stem-like cells in luminal type of cancer and the miR-221 level was correlated with clinical outcome in breast cancer patients. Epithelial-mesenchymal transition (EMT) was induced by overexpression of miR-221 in normal and breast cancer cells. The EMT related gene ATXN1 was found to be a miR-221 target gene regulating breast cell hierarchy. In conclusion, we propose that miR-221 contributes to lineage homeostasis of normal and malignant breast epithelium.
FEBS Letters. Apr, 2015 | Pubmed ID: 25749370
Besides its canonical function of catalyzing the formation of telomeric repeats, many groups have recently reported non-canonical functions of hTERT in particular, and telomerase in general. Regulating transcription is the central basis of non-canonical functions of telomerase. However, unlike reverse transcriptase activity of telomerase that requires only a few molecules of enzymatically active hTERT, non-canonical functions of hTERT or other telomerase components theoretically require several hundred copies. Here, we provide the first direct quantification of all the telomerase components in human cancer cell lines. We demonstrate that telomerase components do not exist in a 1:1 stoichiometric ratio, and there are several hundred copies of hTERT in cells. This provides the molecular basis of hTERT to function in other signaling cascades, including transcription.
The Journal of Clinical Investigation. May, 2015 | Pubmed ID: 25893605
Constitutively active MYC and reactivated telomerase often coexist in cancers. While reactivation of telomerase is thought to be essential for replicative immortality, MYC, in conjunction with cofactors, confers several growth advantages to cancer cells. It is known that the reactivation of TERT, the catalytic subunit of telomerase, is limiting for reconstituting telomerase activity in tumors. However, while reactivation of TERT has been functionally linked to the acquisition of several "hallmarks of cancer" in tumors, the molecular mechanisms by which this occurs and whether these mechanisms are distinct from the role of telomerase on telomeres is not clear. Here, we demonstrated that first-generation TERT-null mice, unlike Terc-null mice, show delayed onset of MYC-induced lymphomagenesis. We further determined that TERT is a regulator of MYC stability in cancer. TERT stabilized MYC levels on chromatin, contributing to either activation or repression of its target genes. TERT regulated MYC ubiquitination and proteasomal degradation, and this effect of TERT was independent of its reverse transcriptase activity and role in telomere elongation. Based on these data, we conclude that reactivation of TERT, a direct transcriptional MYC target in tumors, provides a feed-forward mechanism to potentiate MYC-dependent oncogenesis.
Low Affinity Binding of Plasma Proteins to Lipid-coated Quantum Dots As Observed by in Situ Fluorescence Correlation Spectroscopy
Nanoscale. Jun, 2015 | Pubmed ID: 25975280
Protein binding to lipid-coated nanoparticles has been pursued quantitatively by using fluorescence correlation spectroscopy. The binding of three important plasma proteins to lipid-enwrapped quantum dots (QDs) shows very low affinity, with an apparent dissociation coefficient in the range of several hundred micromolar. Thus, the tendency to adsorb is orders of magnitude weaker than for QDs coated with dihydrolipoic acid.
Plant Physiology. Jul, 2015 | Pubmed ID: 26002908
Sugars not only serve as energy and cellular carbon skeleton but also function as signaling molecules regulating growth and development in plants. Understanding the molecular mechanisms in sugar signaling pathways will provide more information for improving plant growth and development. Here, we describe a sugar-hypersensitive recessive mutant, tang1. Light-grown tang1 mutants have short roots and increased starch and anthocyanin contents when grown on high-sugar concentration medium. Dark-grown tang1 plants exhibit sugar-hypersensitive hypocotyl elongation and enhanced dark development. The tang1 mutants also show an enhanced response to abscisic acid but reduced response to ethylene. Thus, tang1 displays a range of alterations in sugar signaling-related responses. The TANG1 gene was isolated by a map-based cloning approach and encodes a previously uncharacterized unique protein with a predicted Symplekin tight-junction protein C terminus. Expression analysis indicates that TANG1 is ubiquitously expressed at moderate levels in different organs and throughout the Arabidopsis (Arabidopsis thaliana) life cycle; however, its expression is not affected by high-sugar treatment. Genetic analysis shows that PRL1 and TANG1 have additive effects on sugar-related responses. Furthermore, the mutation of TANG1 does not affect the expression of genes involved in known sugar signaling pathways. Taken together, these results suggest that TANG1, a unique gene, plays an important role in sugar responses in Arabidopsis.
The Presystemic Interplay Between Gut Microbiota and Orally Administered Calycosin-7-O-β-D-Glucoside
Drug Metabolism and Disposition: the Biological Fate of Chemicals. Oct, 2015 | Pubmed ID: 26101224
Presystemic interactions with gut microbiota might play important roles in the holistic action of herbal medicines in their traditional oral applications. However, research interests usually focus on biologic activities of the in vivo available herb-derived components and their exposure in circulation. In this study, we illustrated the importance of studying the presystemic interplay with gut microbiota for understanding the holistic actions of medicinal herbs by using calycosin-7-O-β-D-glucoside (C7G), the most abundant flavonoid and chemical marker in Astragali Radix, as a model compound. When C7G was orally administrated to rats, calycosin-3'-O-glucuronide (G2) was the major circulating component in the blood together with a minor calycosin but not C7G. Rat gut microbiota hydrolyzed C7G in vitro rapidly and produced its aglycone calycosin. Calycosin exhibited higher permeability than C7G and further underwent extensive glucuronidation to yield 3'-glucuronide as the dominant metabolite. Bioactivity assays revealed that G2 exhibited similar or more potent proangiogenic effects than calycosin in human umbilical vein endothelial cells in vitro and in the vascular endothelial growth factor receptor tyrosine kinase inhibitor II-induced blood vessel loss model in zebrafish. More interestingly, the incubation of C7G with gut microbiota from both normal and colitic rats showed a probiotics-like effect through stimulating the growth of the beneficial bacteria Lactobacillus and Bifidobacterium. In conclusion, C7G interacts reciprocally with gut microbiota after oral dosing, which makes it not only an angiogenic prodrug but also a modulator of gut microbiota.
Mitochondrial Superoxide Reduction and Cytokine Secretion Skewing by Carbon Nanotube Scaffolds Enhance Ex Vivo Expansion of Human Cord Blood Hematopoietic Progenitors
Nanomedicine : Nanotechnology, Biology, and Medicine. Oct, 2015 | Pubmed ID: 26115640
In this study, we report that surface functional groups of single walled carbon nanotubes (f-SWCNT) are critical for mediating survival and ex vivo expansion of hematopoietic stem and progenitor cells (HSPC) in human umbilical cord blood (UCB). In comparison to amide (-O-NH2) and polyethylene-glycol (-PEG) functionalized SWCNT, carboxylic acid (-COOH) variants gave optimal viability support which correlated with maximal reduction of lethal mitochondrial superoxides in HSPC. Cytokine array illustrated that f-SWCNT-COOH maintained higher proportion of HSPC associated cytokines and minimal level of differentiation promoting factors. Transplantation of f-SWCNT-COOH expanded grafts in sub-lethally irradiated immunodeficient mice resulted in higher engraftment of HSPC in bone marrow compared to control when they were co-transplanted with non-expanded cells from the same UCB. Expanded grafts mediated higher survival rate of mice compared to non-expanded grafts due to lower graft-versus-host-disease which is likely a consequence of proportion of immune cells in the grafts.
Simulations Show Diagnostic Testing For Malaria In Young African Children Can Be Cost-Saving Or Cost-Effective
Health Affairs (Project Hope). Jul, 2015 | Pubmed ID: 26153315
Malaria imposes a substantial global disease burden. It disproportionately affects sub-Saharan Africans, particularly young children. In an effort to improve disease management, the World Health Organization (WHO) recommended in 2010 that countries test children younger than age five who present with suspected malaria fever to confirm the diagnosis instead of treating them presumptively with antimalarial drugs. Costs and concerns about the overall health impact of such diagnostic testing for malaria in children remain barriers to full implementation. Using data from national Malaria Indicator Surveys, we estimated two-stage microsimulation models for Angola, Tanzania, and Uganda to assess the policy's cost-effectiveness. We found that diagnostic testing for malaria in children younger than five is cost-saving in Angola. In Tanzania and Uganda the cost per life-year gained is $5.54 and $94.28, respectively. The costs projected for Tanzania and Uganda are less than the WHO standard of $150 per life-year gained. Our results were robust under varying assumptions about cost, prevalence of malaria, and behavior, and they strongly suggest the pursuit of policies that facilitate full implementation of testing for malaria in children younger than five.
Modified Glasgow Prognostic Score Predicting High Conversion Ratio in Opioid Switching from Oral Oxycodone to Transdermal Fentanyl in Patients with Cancer Pain
International Journal of Clinical and Experimental Medicine. 2015 | Pubmed ID: 26221306
The aim of this study was to identify predictive factors for higher conversion ratio in opioid switching from oral oxycodone to transdermal fentanyl (TDF) in patients with cancer pain. The participants of this study were 156 hospitalized cancer patients who underwent opioid switching from oral oxycodone to TDF at the Affiliated Hospital of Binzhou Medical University between January 1st, 2010 and March 31st, 2014. Patient characteristics, modified Glasgow Prognostic Score (mGPS), daily oxycodone dose, and reasons for opioid switching were retrospectively collected. The effect of variables on the conversion ratio was analyzed by multiple regression analysis to identify the predictive factors for higher conversion ratio in opioid switching from oral oxycodone to TDF. The results showed that the mGPS (odds ratio [OR], 2.358; 95% CI 1.379-4.031; P = 0.002), the reason for opioid switching (OR, 0.497; 95% CI, 0.298-0.828; P = 0.007) and equivalent oral morphine dose (OR, 1.700; 95% CI, 1.008-2.867; P = 0.046) were found to be significant predictors requiring higher conversion ratio in opioid switching. This study indicates that higher mGPS, poor pain control before switching and higher equivalent oral morphine dose are significant predictors of a need for higher conversion ratio in opioid switching from oral oxycodone to TDF. These results could contribute to the establishment of evidence-based medicine in cancer pain relief.
Discovery of Novel Class I Histone Deacetylase Inhibitors with Promising in Vitro and in Vivo Antitumor Activities
Journal of Medicinal Chemistry. Oct, 2015 | Pubmed ID: 26331334
A successful structure-based design of novel cyclic depsipeptides that selectively target class I HDAC isoforms is described. Compound 11 has an IC50 of 2.78 nM for binding to the HDAC1 protein, and the prodrugs 12 and 13 also exhibit promising antiproliferative activities in the nanomolar range against various cancer cell lines. Compounds 12 and 13 show more than 20-fold selectivity toward human cancer cells over human normal cells in comparison with romidepsin (FK228), demonstrating low probability of toxic side effects. In addition, compound 13 exhibits excellent in vivo anticancer activities in a human prostate carcinoma (Du145) xenograft model with no observed toxicity. Thus, prodrug 13 has therapeutic potential as a new class of anticancer agent for further clinical translation.
Loss of MiR-200b Promotes Invasion Via Activating the Kindlin-2/integrin β1/AKT Pathway in Esophageal Squamous Cell Carcinoma: An E-cadherin-independent Mechanism
Oncotarget. Oct, 2015 | Pubmed ID: 26334393
Our previous studies have shown that loss of miR-200b enhances the invasiveness of esophageal squamous cell carcinoma (ESCC) cells. However, whether the miR-200-ZEB1/2-E-cadherin regulatory cascade, a master regulator of epithelial-to-mesenchymal transition (EMT), is involved in the regulation of ESCC invasion remains elusive. Here, we show that miR-200b represses ESCC cell invasion in vivo without altering the expression of E-cadherin and vimentin, two surrogate markers of EMT. However, an inverse correlation was observed between the expression levels of miR-200b and ZEB1/2 in both ESCC cell lines (n = 7, P < 0.05) and ESCC tumor samples (n = 88, P < 0.05). Methylation of E-cadherin gene was found to block the regulation of E-cadherin by the miR-200b-ZEB1/2 axis, indicating that an E-cadherin-independent mechanism can mediate the biological function of miR-200b in ESCC. We revealed that miR-200b suppresses the integrin β1-AKT pathway via targeting Kindlin-2 to mitigate ESCC cell invasiveness. In two independent cohorts of ESCC samples (n = 20 and n = 53, respectively), Kindlin-2 expression positively correlated with the activation status of both the integrin signaling pathway and the PI3K-AKT signaling pathway (both P < 0.01). These data highlight that suppression of the Kindlin-2-integrin β1-AKT regulatory axis is an alternative mechanism underlying the tumor suppressor function of miR-200b in ESCC.
Identification of Genomic Biomarkers Associated with the Clinicopathological Parameters and Prognosis of Esophageal Squamous Cell Carcinoma
Cancer Biomarkers : Section A of Disease Markers. 2015 | Pubmed ID: 26406417
At present no objective prognostic biomarkers have been established in esophageal squamous cell carcinoma (ESCC).
Subpathway-GMir: Identifying MiRNA-mediated Metabolic Subpathways by Integrating Condition-specific Genes, MicroRNAs, and Pathway Topologies
Oncotarget. Nov, 2015 | Pubmed ID: 26472186
MicroRNAs (miRNAs) regulate disease-relevant metabolic pathways. However, most current pathway identification methods fail to consider miRNAs in addition to genes when analyzing pathways. We developed a powerful method called Subpathway-GMir to construct miRNA-regulated metabolic pathways and to identify miRNA-mediated subpathways by considering condition-specific genes, miRNAs, and pathway topologies. We used Subpathway-GMir to analyze two liver hepatocellular carcinomas (LIHC), one stomach adenocarcinoma (STAD), and one type 2 diabetes (T2D) data sets. Results indicate that Subpathway-GMir is more effective in identifying phenotype-associated metabolic pathways than other methods and our results are reproducible and robust. Subpathway-GMir provides a flexible platform for identifying abnormal metabolic subpathways mediated by miRNAs, and may help to clarify the roles that miRNAs play in a variety of diseases. The Subpathway-GMir method has been implemented as a freely available R package.
High-throughput Genotyping of CRISPR/Cas9-mediated Mutants Using Fluorescent PCR-capillary Gel Electrophoresis
Scientific Reports. Oct, 2015 | Pubmed ID: 26498861
Recent advances in the engineering of sequence-specific synthetic nucleases provide enormous opportunities for genetic manipulation of gene expression in order to study their cellular function in vivo. However, current genotyping methods to detect these programmable nuclease-induced insertion/deletion (indel) mutations in targeted human cells are not compatible for high-throughput screening of knockout clones due to inherent limitations and high cost. Here, we describe an efficient method of genotyping clonal CRISPR/Cas9-mediated mutants in a high-throughput manner involving the use of a direct lysis buffer to extract crude genomic DNA straight from cells in culture, and fluorescent PCR coupled with capillary gel electrophoresis. This technique also allows for genotyping of multiplexed gene targeting in a single clone. Overall, this time- and cost-saving technique is able to circumvent the limitations of current genotyping methods and support high-throughput screening of nuclease-induced mutants.
Low Goiter Rate Associated with Small Average Thyroid Volume in Schoolchildren After the Elimination of Iodine Deficiency Disorders
PloS One. 2015 | Pubmed ID: 26513146
After the implementation of the universal salt iodization (USI) program in 1996, seven cross-sectional school-based surveys have been conducted to monitor iodine deficiency disorders (IDD) among children in eastern China.
The Association Between Effort-Reward Imbalance and Depressive Symptoms Is Modified by Selection, Optimization, and Compensation Strategy
Journal of Occupational and Environmental Medicine. Nov, 2015 | Pubmed ID: 26539771
To examine the main and interactive effects of effort-reward imbalance (ERI) and selection, optimization, and compensation (SOC) strategy on depressive symptoms among the working population in the City of Kumning, China.
Scientific Reports. Nov, 2015 | Pubmed ID: 26568398
Formononetin is an isoflavone that has been shown to display estrogenic properties and induce angiogenesis activities. However, the interrelationship between the estrogenic properties and angiogenesis activities of formononetin are not well defined. In the present study, docking and enzymatic assay demonstrated that formononetin displayed direct binding to the ligand-binding domain (LBD) of estrogen receptor alpha (ERα) with an agonistic property. Results from Human Umbilical Vein Endothelial Cells (HUVEC) by using real-time migration xCELLigence system, immunofluorescence and western blotting provided strong evidences of formononetin induced endothelial cell migration and dramatic actin cytoskeleton spatial modification through ERα-enhanced-ROCK-II/MMP2/9 signaling pathways. In addition, results from co-immunoprecipitation suggested formononetin induced cell migration via recruiting of ERα/ROCK-II activated complex formation. More interestingly, in zebrafish embryo we observed that formononetin significantly promoted angiogenic sproutings in the subintestinal vessels (SIVs) that could be completely abolished by ROCK inhibitor. In this study, we elucidated the underlying mechanisms that formononetin produced proangiogenesis effects through an ERα-enhanced ROCK-II signaling pathways. Results from the present study also expand our knowledge about the enigmatic underlying mechanisms of phytoestrogenic compounds in the promotion of angiogenesis in relation to ERα and ROCK interaction in endothelial cells and their relationship with actin assembly and cell migration.
Association Between MUC5B Polymorphism and Susceptibility and Severity of Idiopathic Pulmonary Fibrosis
International Journal of Clinical and Experimental Pathology. 2015 | Pubmed ID: 26823827
Idiopathic pulmonary fibrosis (IPF) is a group of lung diseases that cause irreversible architectural distortion and impair gas, and finally progressive pulmonary functional decline and death, in which the common variant in the promoter region of the mucin 5B (MUC5B) gene may be involved. The present study aims to investigate whether variants within the MUC5B gene rs35705950 contributed to IPF susceptibility and severity in Chinese Han Population.
The International Journal of Biochemistry & Cell Biology. Jun, 2016 | Pubmed ID: 26408503
Metal nanoclusters (NCs) are a new type of nanoprobe with great potential in various biological applications. For biocompatible and efficient utilization of NCs, a thorough understanding of their interactions with biological systems is highly important. Herein, we focus on recent studies addressing interactions between metal NCs and proteins as well as implications for their further biological application. These findings show that protein adsorption not only affects the photophysical properties of NCs, but also influences their subsequent biological behavior, i.e., cellular uptake and cytotoxicity. Moreover, specific protein-NC interactions have also been harnessed to develop novel protein discrimination strategies.
In Situ Monitoring of the Intracellular Stability of Nanoparticles by Using Fluorescence Lifetime Imaging
Small (Weinheim an Der Bergstrasse, Germany). Feb, 2016 | Pubmed ID: 26708212
FLIMaging nanoparticle degradation: semiconductor and metal nanoparticle degradation has been observed in live cells over 3 d via the change of the characteristic luminescence lifetime using fluorescence lifetime imaging microscopy (FLIM). Thus, FLIM is a simple yet robust tool to examine the intracellular stability of photoluminescent nanoparticles in live cells, tissues, and organisms.
Mitotic Regulator Nlp Interacts with XPA/ERCC1 Complexes and Regulates Nucleotide Excision Repair (NER) in Response to UV Radiation
Cancer Letters. Apr, 2016 | Pubmed ID: 26805762
Cellular response to DNA damage, including ionizing radiation (IR) and UV radiation, is critical for the maintenance of genomic fidelity. Defects of DNA repair often result in genomic instability and malignant cell transformation. Centrosomal protein Nlp (ninein-like protein) has been characterized as an important cell cycle regulator that is required for proper mitotic progression. In this study, we demonstrate that Nlp is able to improve nucleotide excision repair (NER) activity and protects cells against UV radiation. Upon exposure of cells to UVC, Nlp is translocated into the nucleus. The C-terminus (1030-1382) of Nlp is necessary and sufficient for its nuclear import. Upon UVC radiation, Nlp interacts with XPA and ERCC1, and enhances their association. Interestingly, down-regulated expression of Nlp is found to be associated with human skin cancers, indicating that dysregulated Nlp might be related to the development of human skin cancers. Taken together, this study identifies mitotic protein Nlp as a new and important member of NER pathway and thus provides novel insights into understanding of regulatory machinery involved in NER.
Construction and Analysis of Cardiac Hypertrophy-associated LncRNA-mRNA Network Based on Competitive Endogenous RNA Reveal Functional LncRNAs in Cardiac Hypertrophy
Oncotarget. Mar, 2016 | Pubmed ID: 26872060
Cardiac hypertrophy (CH) could increase cardiac after-load and lead to heart failure. Recent studies have suggested that long non-coding RNA (lncRNA) played a crucial role in the process of the cardiac hypertrophy, such as Mhrt, TERMINATOR. Some studies have further found a new interacting mechanism, competitive endogenous RNA (ceRNA), of which lncRNA could interact with micro-RNAs (miRNA) and indirectly interact with mRNAs through competing interactions. However, the mechanism of ceRNA regulated by lncRNA in the CH remained unclear. In our study, we generated a global triple network containing mRNA, miRNA and lncRNA, and extracted a CH related lncRNA-mRNA network (CHLMN) through integrating the data from starbase, miRanda database and gene expression profile. Based on the ceRNA mechanism, we analyzed the characters of CHLMN and found that 3 lncRNAs (SLC26A4-AS1, RP11-344E13.3 and MAGI1-IT1) were high related to CH. We further performed cluster module analysis and random walk with restart for the CHLMN, finally 14 lncRNAs had been discovered as the potential CH related disease genes. Our results showed that lncRNA played an important role in the CH and could shed new light to the understanding underlying mechanisms of the CH.
Super-resolution Imaging-based Single Particle Tracking Reveals Dynamics of Nanoparticle Internalization by Live Cells
Nanoscale. Apr, 2016 | Pubmed ID: 27001905
By combining super-resolution photoactivation localization microscopy with single particle tracking, we have visualized the endocytic process in the live-cell environment with nanoparticles (NPs) of different size and surface functionalization. This allowed us to analyze the dynamics of NPs interacting with cells with high spatial and temporal resolution. We identified two distinctly different types of pathways by which NPs are internalized via clathrin-coated pits (CCPs). Predominantly, NPs first bind to the membrane and, subsequently, CCPs form at this site. However, there are also instances where a NP diffuses on the membrane and utilizes a preformed CCP. Moreover, we have applied this new method to further explore the effects of size and surface functionalization on the NP dynamics on the plasma membrane and the ensuing endocytosis.
ANO1 Protein As a Potential Biomarker for Esophageal Cancer Prognosis and Precancerous Lesion Development Prediction
Oncotarget. Apr, 2016 | Pubmed ID: 27016410
Anoctamin 1 (ANO1) has been found to be overexpressed in esophageal squamous cell carcinoma (ESCC) in our previous study. Herein we showed the clinical relevance of ANO1 alterations with ESCC and esophageal precancerous lesion progression.
SpringerPlus. 2016 | Pubmed ID: 27026929
In recent studies, sulforaphane (SFN) has been seen to demonstrate antioxidant and anti-tumor activities. In the present study, the viability inhibition effects of SFN in U251MG glioblastoma cells were analyzed by MTS. Morphology changes were observed by microscope. Apoptotic effects of SFN were evaluated by annexin V binding capacity with flow cytometric analysis. Invasion inhibition effects of SFN were tested by the invasion assay. The molecular mechanisms of apoptotic effects and invasion inhibition effects of SFN were detected by western blot and gelatin zymography. The results indicated that SFN has potent apoptotic effects and invasion inhibition effects against U251MG glioblastoma cells. These effects are both dose dependent. Taken together, SFN possessed apoptotic activity on U251MG cells indicated by increased annexin V-binding capacity, Bad, Bax, cytochrome C expression, and decreased Bcl-2 and survivin expressions. SFN inhibited invasion in U251MG cells via upregulation of E-cadherin and downregulation of MMP-2, MMP-9 and Galectin-3.
Gut. May, 2016 | Pubmed ID: 27196599
Oesophageal squamous cell carcinoma (OSCC) is an aggressive malignancy and the major histological subtype of oesophageal cancer. Although recent large-scale genomic analysis has improved the description of the genetic abnormalities of OSCC, few targetable genomic lesions have been identified, and no molecular therapy is available. This study aims to identify druggable candidates in this tumour.
Distinct Responses of Stem Cells to Telomere Uncapping-A Potential Strategy to Improve the Safety of Cell Therapy
Stem Cells (Dayton, Ohio). Oct, 2016 | Pubmed ID: 27299710
In most human somatic cells, the lack of telomerase activity results in progressive telomere shortening during each cell division. Eventually, DNA damage responses triggered by critically short telomeres induce an irreversible cell cycle arrest termed replicative senescence. However, the cellular responses of human pluripotent stem cells to telomere uncapping remain unknown. We generated telomerase knockout human embryonic stem (ES) cells through gene targeting. Telomerase inactivation in ES cells results in progressive telomere shortening. Telomere DNA damage in ES cells and neural progenitor cells induces rapid apoptosis when telomeres are uncapped, in contrast to fibroblast cells that enter a state of replicative senescence. Significantly, telomerase inactivation limits the proliferation capacity of human ES cells without affecting their pluripotency. By targeting telomerase activity, we can functionally separate the two unique properties of human pluripotent stem cells, namely unlimited self-renewal and pluripotency. We show that the potential of ES cells to form teratomas in vivo is dictated by their telomere length. By controlling telomere length of ES cells through telomerase inactivation, we can inhibit teratoma formation and potentially improve the safety of cell therapies involving terminally differentiated cells as well as specific progenitor cells that do not require sustained cellular proliferation in vivo, and thus sustained telomerase activity. Stem Cells 2016;34:2471-2484.
European Journal of Pharmacology. Oct, 2016 | Pubmed ID: 27471159
Andrographolide is among the most promising anti-tumor and anti-angiogenic components in Andrographis paniculata but its poor bioavailability and limited efficacy pose difficulties for its therapeutic development. Therefore, improving its pharmaceutical features and potency, by modifying its chemical structure, is desirable. In the present study, a new andrographolide derivative (AGP-40) was synthesized and characterized for its anti-angiogenic properties. Human umbilical vein endothelial cells (HUVECs) and zebrafish models were used to identify the anti-angiogenic activity of AGP-40. AGP-40 significantly suppressed the formation of blood vessels in zebrafish and inhibited proliferation, migration and tube formation in vitro. The anti-angiogenic effects of AGP-40 are at least partially mediated via the PI3K/Akt and MEK/Erk(1/2) signaling pathways. Furthermore, AGP-40 exhibited stronger anti-proliferative effects than andrographolide against A549, HepG2, Hela cancer cell lines. This study is the first to demonstrate the promising anti-angiogenic activity of the new andrographolide derivative AGP-40. Our results indicate that AGP-40 could serve as a potential therapeutic agent for the treatment and prevention of diseases associated with excessive angiogenesis.
RWCFusion: Identifying Phenotype-specific Cancer Driver Gene Fusions Based on Fusion Pair Random Walk Scoring Method
Oncotarget. Sep, 2016 | Pubmed ID: 27506935
While gene fusions have been increasingly detected by next-generation sequencing (NGS) technologies based methods in human cancers, these methods have limitations in identifying driver fusions. In addition, the existing methods to identify driver gene fusions ignored the specificity among different cancers or only considered their local rather than global topology features in networks. Here, we proposed a novel network-based method, called RWCFusion, to identify phenotype-specific cancer driver gene fusions. To evaluate its performance, we used leave-one-out cross-validation in 35 cancers and achieved a high AUC value 0.925 for overall cancers and an average 0.929 for signal cancer. Furthermore, we classified 35 cancers into two classes: haematological and solid, of which the haematological got a highly AUC which is up to 0.968. Finally, we applied RWCFusion to breast cancer and found that top 13 gene fusions, such as BCAS3-BCAS4, NOTCH-NUP214, MED13-BCAS3 and CARM-SMARCA4, have been previously proved to be drivers for breast cancer. Additionally, 8 among the top 10 of the remaining candidate gene fusions, such as SULF2-ZNF217, MED1-ACSF2, and ACACA-STAC2, were inferred to be potential driver gene fusions of breast cancer by us.
Molecular BioSystems. Oct, 2016 | Pubmed ID: 27539139
Esophageal cancer (EC) is the sixth most common cause of death from cancer and has two principal histological subtypes: esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC). In addition, Barrett's esophagus (BE), due to its strong association with EAC, is generally considered to be a premalignant condition of EAC. lncRNAs are believed to function in initiation and progression of multiple cancers, and therefore should play prominent, but unknown roles in the determination and behavior of different EC subtypes. In this study, by using expression profile re-annotation and differential expression (DE) analysis, we identified DE-lncRNAs and DE-protein-coding genes (DE-PCGs), and then constructed a lncRNA-PCG network, using co-expressed DE-lncRNAs (550) and DE-PCGs (5236), which was also annotated for EC subtypes. After module mining of the network, we obtained twenty candidate lncRNA-PCG modules that were ranked by gene expression and subtype-specification. Within the top four modules, we identified an ESCC specific module, two EAC-BE-specific modules and a heterologous module. Novel candidate lncRNAs were identified, in addition to lncRNAs known to be functionally connected to EC, and could be responsible for the subtype disparities in the GO biological process and at pathway levels.
Genes. Aug, 2016 | Pubmed ID: 27548225
Embryonic stem cells and induced pluripotent stem cells have the ability to maintain their telomere length via expression of an enzymatic complex called telomerase. Similarly, more than 85%-90% of cancer cells are found to upregulate the expression of telomerase, conferring them with the potential to proliferate indefinitely. Telomerase Reverse Transcriptase (TERT), the catalytic subunit of telomerase holoenzyme, is the rate-limiting factor in reconstituting telomerase activity in vivo. To date, the expression and function of the human Telomerase Reverse Transcriptase (hTERT) gene are known to be regulated at various molecular levels (including genetic, mRNA, protein and subcellular localization) by a number of diverse factors. Among these means of regulation, transcription modulation is the most important, as evident in its tight regulation in cancer cell survival as well as pluripotent stem cell maintenance and differentiation. Here, we discuss how hTERT gene transcription is regulated, mainly focusing on the contribution of trans-acting factors such as transcription factors and epigenetic modifiers, as well as genetic alterations in hTERT proximal promoter.
Small (Weinheim an Der Bergstrasse, Germany). Sep, 2016 | Pubmed ID: 27606563
Biological responses of cells and organisms to nanoparticle exposure crucially depend on the properties of the protein adsorption layer ("protein corona") forming on nanoparticle surfaces and their characterization is a crucial step toward a deep, mechanistic understanding of their build-up. Previously, adsorption of one type of model protein on nanoparticles was systematically studied in situ by using fluorescence correlation spectroscopy. Here, the first such study of interactions is presented between water-solubilized CdSe/ZnS quantum dots (QDs) and a complex biofluid, human blood serum. Despite the large number of proteins in serum, a protein layer of well-defined (average) thickness forming on QD surfaces is observed. Both the thickness and the apparent binding affinity depend on the type of QD surface ligand. Kinetic experiments reveal that the protein corona formed from serum is irreversibly bound, whereas the one formed from human serum albumin was earlier observed to be reversible. By using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry, the most abundant serum proteins contributing to the formation of a hard corona on the QDs are identified.
Subpathway-CorSP: Identification of Metabolic Subpathways Via Integrating Expression Correlations and Topological Features Between Metabolites and Genes of Interest Within Pathways
Scientific Reports. Sep, 2016 | Pubmed ID: 27625019
Metabolic pathway analysis is a popular strategy for comprehensively researching metabolites and genes of interest associated with specific diseases. However, the traditional pathway identification methods do not accurately consider the combined effect of these interesting molecules and neglects expression correlations or topological features embedded in the pathways. In this study, we propose a powerful method, Subpathway-CorSP, for identifying metabolic subpathway regions. This method improved on original pathway identification methods by using a subpathway identification strategy and emphasizing expression correlations between metabolites and genes of interest based on topological features within the metabolic pathways. We analyzed a prostate cancer data set and its metastatic sub-group data set with detailed comparison of Subpathway-CorSP with four traditional pathway identification methods. Subpathway-CorSP was able to identify multiple subpathway regions whose entire corresponding pathways were not detected by traditional pathway identification methods. Further evidences indicated that Subpathway-CorSP provided a robust and efficient way of reliably recalling cancer-related subpathways and locating novel subpathways by the combined effect of metabolites and genes. This was a novel subpathway strategy based on systematically considering expression correlations and topological features between metabolites and genes of interest within given pathways.
The Journal of Clinical Investigation. Oct, 2016 | Pubmed ID: 27643433
Transcriptional reactivation of telomerase reverse transcriptase (TERT) reconstitutes telomerase activity in the majority of human cancers. Here, we found that ectopic TERT expression increases cell proliferation, while acute reductions in TERT levels lead to a dramatic loss of proliferation without any change in telomere length, suggesting that the effects of TERT could be telomere independent. We observed that TERT determines the growth rate of cancer cells by directly regulating global protein synthesis independently of its catalytic activity. Genome-wide TERT binding across 5 cancer cell lines and 2 embryonic stem cell lines revealed that endogenous TERT, driven by mutant promoters or oncogenes, directly associates with the RNA polymerase III (pol III) subunit RPC32 and enhances its recruitment to chromatin, resulting in increased RNA pol III occupancy and tRNA expression in cancers. TERT-deficient mice displayed marked delays in polyomavirus middle T oncogene-induced (PyMT-induced) mammary tumorigenesis, increased survival, and reductions in tRNA levels. Ectopic expression of either RPC32 or TERT restored tRNA levels and proliferation defects in TERT-depleted cells. Finally, we determined that levels of TERT and tRNA correlated in breast and liver cancer samples. Together, these data suggest the existence of a unifying mechanism by which TERT enhances translation in cells to regulate cancer cell proliferation.
Nature Communications. Sep, 2016 | Pubmed ID: 27677335
Regulatory enhancer elements in solid tumours remain poorly characterized. Here we apply micro-scale chromatin profiling to survey the distal enhancer landscape of primary gastric adenocarcinoma (GC), a leading cause of global cancer mortality. Integrating 110 epigenomic profiles from primary GCs, normal gastric tissues and cell lines, we highlight 36,973 predicted enhancers and 3,759 predicted super-enhancers respectively. Cell-line-defined super-enhancers can be subclassified by their somatic alteration status into somatic gain, loss and unaltered categories, each displaying distinct epigenetic, transcriptional and pathway enrichments. Somatic gain super-enhancers are associated with complex chromatin interaction profiles, expression patterns correlated with patient outcome and dense co-occupancy of the transcription factors CDX2 and HNF4α. Somatic super-enhancers are also enriched in genetic risk SNPs associated with cancer predisposition. Our results reveal a genome-wide reprogramming of the GC enhancer and super-enhancer landscape during tumorigenesis, contributing to dysregulated local and regional cancer gene expression.
Downregulation of Oncogenic RAS and C-Myc Expression in MOLT-4 Leukaemia Cells by a Salicylaldehyde Semicarbazone Copper(II) Complex
Scientific Reports. Nov, 2016 | Pubmed ID: 27841290
Copper complexes with potent anti-tumor effect have been extensively developed. Most investigations of their modes of action focused on the biomolecular targets but not the signal transduction between target binding and cell death. We have previously shown that the cytotoxic complex pyridine(2,4-dihydroxybenzaldehyde dibenzyl semicarbazone)copper(II) (complex 1) shows selective binding to human telomeric G-quadruplex DNA over double-stranded DNA in vitro. Herein, we elucidate the mechanism of action by which complex 1 induces apoptosis in MOLT-4 cells. Complex 1 accumulates in the nuclei and differentially downregulates the expression of c-Myc, c-Kit and KRAS oncogenes. Chemical affinity capture assay results show that the complex is associated with c-Myc and KRAS quadruplex sequences in MOLT-4 cells. We further showed that the reduction in Ras protein expression resulted in attenuated MEK-ERK and PI3K-Akt signalling activities, leading to the activation of caspase-dependent apoptosis. Notably, complex 1 increased the sensitivity of MOLT-4 cells to cisplatin and vice versa. Overall, we demonstrated that complex 1 induces apoptosis, at least in part, by suppressing KRAS, c-Kit and c-Myc oncogene expression and the pro-survival MEK-ERK and PI3K-Akt signalling pathways.
Tumor-cell Targeting Polydiacetylene Micelles Encapsulated with an Antitumor Drug for the Treatment of Ovarian Cancer
Chemical Communications (Cambridge, England). Jan, 2017 | Pubmed ID: 27995230
Peptide functionalized polydiacetylene (PDA) micelles encapsulated with camptothecin (CPT) kill ovarian cancer cells by the lysosome release of anticancer drug CPT. Moreover, the sub-30 nm PDA micelles penetrate efficiently into a tumor for enhanced therapeutic efficacy.
Biomaterials. Mar, 2017 | Pubmed ID: 28011190
Efficient and site-specific delivery of anticancer drugs to tumors is important in the development of effective cancer chemotherapy. As an undecapeptide of the tachykinin neuropeptide family, the substance P (SP)/neurokinin-1 receptor (NK1R) system has been identified as a promising ligand-receptor pair in tumor-specific drug delivery. However, the rational design of suitable theranostic agents with high drug loading capacity and tumor targeting for cancer patients remains a great challenge. Herein, we report a dendritic strategy that utilizes the two amine functionalities of lysine to create branch points that allow conjugation of the anticancer drug 5-fluorouracil (5-FU) to the tumor-targeting ligand substance P, along with an additional near-infrared (NIR) squaraine dye, to construct a theranostic dendritic agent, P-FU 4. This cytotoxic theranostic agent, containing four carboxyl-modified 5-FU molecules, has several desirable advantages: i) the ability to self-assemble into nanoparticles; ii) enhanced cytotoxicity with high drug loading capacity (16%) and a specific receptor-targeted interaction with NK1R through the SP moiety; and iii) a high NIR squaraine fluorescence efficiency due to the specific dendron isolation, avoiding aggregation-mediated quenching. As demonstrated in this report, the cytotoxic activity of P-FU 4 is dose-dependent against the tested cancer cells. The improved drug loading capacity with dendritic branching distinctly enhanced cytotoxicity to tumor cells but had little effect on the viability of normal cells. P-FU 4 was preferentially taken up by tumor cells through a receptor-mediated interaction, which was monitored by effective NIR fluorescence with high tissue penetration. Studies using a mouse model revealed that P-FU 4 can significantly inhibit tumor progression, with a tumor-inhibition rate of 60.2%. The receptor-targeted cytotoxic dendritic theranostic agent is highly preferable to standard chemotherapeutic treatments and decreases the negative side effects of medications on healthy cells, which establishes its utility in drug delivery and cancer chemotherapy.
Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Jan, 2017 | Pubmed ID: 28034904
PARP inhibitors have shown promising results in early studies for treatment of breast cancer susceptibility gene (BRCA)-deficient breast cancers; however, resistance ultimately develops. Furthermore, the benefit of PARP inhibitors (PARPi) in triple-negative breast cancers (TNBC) remains unknown. Recent evidence indicates that in TNBCs, cells that display "cancer stem cell" properties are resistant to conventional treatments, mediate tumor metastasis, and contribute to recurrence. The sensitivity of breast cancer stem cells (CSC) to PARPi is unknown.
Cell Death & Disease. Jan, 2017 | Pubmed ID: 28079885
The deregulation of lineage control programs is often associated with the progression of haematological malignancies. The molecular regulators of lineage choices in the context of tyrosine kinase inhibitor (TKI) resistance remain poorly understood in chronic myeloid leukemia (CML). To find a potential molecular regulator contributing to lineage distribution and TKI resistance, we undertook an RNA-sequencing approach for identifying microRNAs (miRNAs). Following an unbiased screen, elevated miRNA182-5p levels were detected in Bcr-Abl-inhibited K562 cells (CML blast crisis cell line) and in a panel of CML patients. Earlier, miRNA182-5p upregulation was reported in several solid tumours and haematological malignancies. We undertook a strategy involving transient modulation and CRISPR/Cas9 (clustered regularly interspersed short palindromic repeats)-mediated knockout of the MIR182 locus in CML cells. The lineage contribution was assessed by methylcellulose colony formation assay. The transient modulation of miRNA182-5p revealed a biased phenotype. Strikingly, Δ182 cells (homozygous deletion of MIR182 locus) produced a marked shift in lineage distribution. The phenotype was rescued by ectopic expression of miRNA182-5p in Δ182 cells. A bioinformatic analysis and Hes1 modulation data suggested that Hes1 could be a putative target of miRNA182-5p. A reciprocal relationship between miRNA182-5p and Hes1 was seen in the context of TK inhibition. In conclusion, we reveal a key role for miRNA182-5p in restricting the myeloid development of leukemic cells. We propose that the Δ182 cell line will be valuable in designing experiments for next-generation pharmacological interventions.
An Andrographolide Derivative AGP-26b Exhibiting Anti-angiogenic Activity in HUVECs and Zebrafish Via Blocking the VEGFA/VEGFR2 Signaling Pathway
Molecular BioSystems. Feb, 2017 | Pubmed ID: 28098292
The aim of this study is to investigate the anti-angiogenic properties of andrographolide derivatives AGP-26a (12β-isomer), AGP-26b (12α-isomer) and AGP-26 (4 : 1 mixture of AGP-26a and AGP-26b) in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) and the Tg(fli-1a:EGFP)y1 zebrafish model were used to identify the anti-angiogenic activities of AGP-26, AGP-26a, and AGP-26b. The results showed that AGP-26b exhibits the strongest inhibitory effect on VEGF-induced proliferation, migration, invasion and formation of capillary-like structures in HUVECs. In the zebrafish model, AGP-26b also showed the strongest suppression of ISV development. Further studies showed that the underlying mechanism of the anti-angiogenic effects of AGP-26b was at least partly through the blockage of the VEGF/VEGFR2 signaling pathways. AGP-26b blocked the activation of VEGFR2. Consequently, the phosphorylation of key intracellular proangiogenic kinases such as Src family kinase (Src), focal adhesion kinase (Fak), mitogen-activated protein kinase (MEK), extracellular signal-regulated kinase 1 and 2 (Erk1/2) and Akt induced by VEGF was suppressed by treatment with AGP-26b. Moreover, AGP-26b reduced the protein expression of matrix metalloproteinases (MMP-9 but not MMP-2) in HUVECs. These results provide evidence supporting the notion that AGP-26b may serve as a potential therapeutic anti-angiogenic agent.
In Situ Characterization of Protein Adsorption Onto Nanoparticles by Fluorescence Correlation Spectroscopy
Accounts of Chemical Research. Feb, 2017 | Pubmed ID: 28145686
Nanotechnology holds great promise for applications in many fields including biology and medicine. Unfortunately, the processes occurring at the interface between nanomaterials and living systems are exceedingly complex and not yet well understood, which has significantly hampered the realization of many nanobiotechnology applications. Whenever nanoparticles (NPs) are incorporated by a living organism, a protein adsorption layer, also known as the "protein corona", forms on the NP surface. Accordingly, living organisms interact with protein-coated rather than bare NPs, and their biological responses depend on the nature of the protein corona. In recent years, a wide variety of biophysical techniques have been employed to elucidate mechanistic aspects of NP-protein interactions. In most studies, NPs are immersed in protein or biofluid (e.g., blood serum) solutions and then separated from the liquid for analysis. Because this approach may modify the composition and structure of the protein corona, our group has pioneered the use of fluorescence correlation spectroscopy (FCS) as an in situ technique, capable of examining NP-protein interactions while the NPs are suspended in biological fluids. FCS allows us to measure, with subnanometer precision and as a function of protein concentration, the increase in hydrodynamic radius of the NPs due to protein adsorption. This Account aims at reviewing recent progress in the exploration of NP-protein interactions by using FCS. In vitro FCS studies of the adsorption of important serum proteins onto water-solubilized luminescent NPs always showed a stepwise increase of the NP radius upon protein binding in the form of a binding isotherm, regardless of the type of NP and its specific surface functionalization. This observation indicates formation of a protein monolayer on the NP. Structure-based calculations of protein surface potentials revealed that positively charged patches on the proteins interact electrostatically with negatively charged NP surfaces, and the observed protein layer thickness always matched the known molecular dimensions of the proteins binding in certain orientations. Temperature and NP surface functionalization have also been identified as important parameters controlling protein corona formation. Notably, while the corona formed from a single type of serum protein was reversible, protein adsorption from complex biological media such as blood serum was entirely irreversible. These quantitative in vitro studies are of great relevance to the bio-nano community and especially to researchers developing engineered nanomaterials for biological and biomedical applications. Future efforts will be directed toward elucidating kinetic aspects of protein corona formation and the detailed structure of the adsorbed proteins at the molecular level. To better appreciate the biological responses triggered by NP exposure, more efforts will be devoted to the exploration of the biomolecular corona as it forms on NPs in contact with living cells, tissues, and even entire model organisms. These studies are challenging when performed in a well-controlled and quantitative fashion and rely on the availability of sophisticated analytical tools, particularly, quantitative optical imaging techniques including FCS and related fluctuation methods.
Ultrasmall Pt Nanoclusters As Robust Peroxidase Mimics for Colorimetric Detection of Glucose in Human Serum
ACS Applied Materials & Interfaces. Mar, 2017 | Pubmed ID: 28244734
In this work, a new type of ultrasmall Pt nanoclusters (Pt NCs) was prepared via a facile one-pot approach by using yeast extract as the reductant and stabilizer. Besides their excellent water solubility, these yeast extract-stabilized Pt NCs also possess attractive peroxidase mimicking property. They can efficiently catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the coexistence of hydrogen peroxide (H2O2). Catalytic mechanism analysis suggested that the peroxidase mimicking activity of these Pt NCs might originate from their characteristic of accelerating electron transfer between TMB and H2O2, and their enzymatic kinetics followed typical Michaelis-Menten theory. On the basis of these findings, we developed a new highly sensitive colorimetric method for glucose detection, and the limit of detection was calculated as low as 0.28 μM (S/N = 3). Further application of the present system for glucose detection in human serum has been successfully demonstrated, suggesting its promising utilization as robust peroxidase mimics in the clinical diagnosis, pharmaceutical, and environmental chemistry fields.
Redox-Neutral α-Arylation of Alkyl Nitriles with Aryl Sulfoxides: A Rapid Electrophilic Rearrangement
Journal of the American Chemical Society. Mar, 2017 | Pubmed ID: 28245112
A facile α-arylation of nitriles has been developed by simply introducing Tf2O and DABCO to the mixture of nitriles and aryl sulfoxides. The transformation consists of two sequential steps: (i) Tf2O-initiated electrophilic assembly and and (ii) DABCO-triggered rearrangement. Each step can be tuned independently by changing the temperature and/or base. This adjustability allows the method to accommodate a wide range of substrates. Notable features of this new protocol include remarkable efficiency (20 min, -30 °C), exclusive regioselectivity, and high functional group compatibility, which can be challenging issues in traditional approaches. NMR studies not only identified a unique, highly unstable sulfonium imine complex but also demonstrated the importance of temperature in the formation and manipulation of this key intermediate. Further DFT calculations suggested that an electrophilic assembly, followed by removal of HOTf (by base), and finally [3,3]-sigmatropic rearrangement are three key stages in the reaction. The versatile transformability of the products and easy scalability of this reaction are also exhibited here.