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Find video protocols related to scientific articles indexed in Pubmed.
Slow Binding and Conformation Selective Properties of ERK1/2 Inhibitors.
Biochemistry
PUBLISHED: 10-29-2014
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The mitogen-activated protein (MAP) kinase pathway is a validated target for anti-cancer therapy. Clinical outcomes with inhibitors of pathway effectors , B-Raf and MKK1/2, demonstrate acquired resistance via up-regulation of the kinase activity of extracellular signal-regulated kinases 1 and 2 (ERK1/2). Thus, inhibitors of ERK1/2, alone or in combination with other MAP kinase inhibitors, are potentially important therapeutic treatments for tumors with acquired resistance. The structures and potencies of different ERK inhibitors have been published, but their mechanistic and kinetic characteristics have not been compared. Here we perform kinetic studies on six representative ERK inhibitors, with potencies varying from 100 pM to 20 µM. Compounds with significant biological activity (IC50<100 nM) that inhibit in the sub-nanomolar range (Vertex-11e, SCH772984) display slow-onset inhibition and represent the first inhibitors of ERK2 known to demonstrate slow dissociation (0.2 h-1 and 1.1 h-1, respectively). By developing a kinetic competition assay, we demonstrate that Vertex-11e binds with differing affinities to inactive, unphosphorylated vs active, phosphorylated forms of ERK2. NMR HMQC measurements show that Vertex-11e favors distinct conformational states in the inactive vs active forms. Thus, a high affinity, slow dissociation inhibitor of ERK favors different enzyme conformations depending on the activity state of the kinase.
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Transcriptional coactivator CBP upregulates hTERT expression and tumor growth and predicts poor prognosis in human lung cancers.
Oncotarget
PUBLISHED: 10-09-2014
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Upregulated expression and activation of human telomerase reverse transcriptase (hTERT) is a hallmarker of lung tumorigenesis. However, the mechanism underlying the aberrant hTERT activity in lung cancer cells remains poorly understood. In this study, we found the transcriptional co-activator CBP as a new hTERT promoter-binding protein that regulated hTERT expression and tumor growth in lung adenocarcinoma cells using a biotin-streptavidin-bead pulldown technique. Chromatin immunoprecipitation assay verified the immortalized cell and tumor cell-specific binding of CBP on hTERT promoter. Overexpression of exogenous CBP upregulated the expression of the hTERT promoter-driven luciferase and endogenous hTERT protein in lung cancer cells. Conversely, inhibition of CBP by CBP-specific siRNA or its chemical inhibitor repressed the expression of hTERT promoter-driven luciferase and endogenous hTERT protein as well as telomerase activity. Moreover, inhibition of CBP expression or activity also significantly reduced the proliferation of lung cancer cells in vitro and tumor growth in an xenograft mouse model in vivo. Immunohistochemical analysis of tissue microarrays of lung cancers revealed a positive correlation between CBP and hTERT. Importantly, the patients with high CBP and hTERT expression had a significantly shorter overall survival. Furthermore, CBP was found to interact with and acetylate transactivator Sp1 in lung cancer cells. Inhibition of CBP by CBP-specific siRNA or its chemical inhibitor significantly inhibited Sp1 acetylation and its binding to the hTERT promoter. Collectively, our results indicate that CBP contributes to the upregulation of hTERT expression and tumor growth, and overexpression of CBP predicts poor prognosis in human lung cancers.
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Soluble toll-like receptor 2 is significantly elevated in HIV-1 infected breast milk and inhibits HIV-1 induced cellular activation, inflammation and infection.
AIDS
PUBLISHED: 09-30-2014
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We previously demonstrated that immunodepletion of soluble Toll-like receptor 2 (sTLR2) from human breast milk significantly increased HIV infection in vitro. The aims of this study were to characterize sTLR2 levels in breast milk from HIV-infected and uninfected women, and identify a mechanism by which sTLR2 inhibits HIV-induced cellular activation and infection.
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A small synthetic molecule forms selective potassium channels to regulate cell membrane potential and blood vessel tone.
Org. Biomol. Chem.
PUBLISHED: 09-03-2014
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In living cell membranes, K(+) permeability is higher than that of other ions such as Na(+) and Cl(-) owing to abundantly expressed K(+) channels. Polarized membrane potential is mainly established by K(+) outward flow because the K(+) concentration in the intracellular side is much higher than that in the extracellular side. We have found that the small synthetic molecule 1 is capable of self-assembling into selective K(+) channels, enhancing K(+) permeability and hyperpolarizing liposome membrane potential. Interestingly, molecule 1 also functions as K(+) channel hyperpolarizing living cell membrane potential and relaxing agonist-induced blood vessel contraction. Therefore, it may have the potential to become a lead compound for the treatment of human diseases associated with K(+) channel dysfunction.
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[Association of glucose transporter 4 gene polymorphism with hypoxia caused by obstructive sleep apnea syndrome and with related inflammatory factors].
Zhongguo Yi Xue Ke Xue Yuan Xue Bao
PUBLISHED: 09-02-2014
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To investigate the relationship between genetic polymorphisms of glucose transporter 4 (GLUT4) and hypoxia caused by obstructive sleep apnea syndrome (OSAS) as well as with related inflammatory factors.
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Gamabufotalin, a bufadienolide compound from toad venom, suppresses COX-2 expression through targeting IKK?/NF-?B signaling pathway in lung cancer cells.
Mol. Cancer
PUBLISHED: 08-31-2014
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Gamabufotalin (CS-6), a major bufadienolide of Chansu, has been used for cancer therapy due to its desirable metabolic stability and less adverse effect. However, the underlying mechanism of CS-6 involved in anti-tumor activity remains poorly understood.
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Elevated expression of long intergenic non-coding RNA HOTAIR in a basal-like variant of MCF-7 breast cancer cells.
Mol. Carcinog.
PUBLISHED: 08-15-2014
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Epigenetic regulation of gene expression is critical to phenotypic maintenance and transition of human breast cancer cells. HOX antisense intergenic RNA (HOTAIR) is a long intergenic non-coding RNA that epigenetically represses gene expression via recruitment of enhancer of zeste homolog 2 (EZH2), a histone methyltransferase. Elevated expression of HOTAIR promotes progression of breast cancer. In the current study we examined the expression and function of HOTAIR in MCF-7-TNR cells, a derivative of the luminal-like breast cancer cell line MCF-7 that acquired resistance to TNF-?-induced cell death. The expression of HOTAIR, markers of the luminal-like and basal-like subtypes, and growth were compared between MCF-7 and MCF-7-TNR cells. These variables were further assessed upon inhibition of HOTAIR, EZH2, p38 MAPK, and SRC kinase in MCF-7-TNR cells. When compared with MCF-7 cells, MCF-7-TNR cells exhibited an increase in the expression of HOTAIR, which correlated with characteristics of a luminal-like to basal-like transition as evidenced by dysregulated gene expression and accelerated growth. MCF-7-TNR cells exhibited reduced suppressive histone H3 lysine27 trimethylation on the HOTAIR promoter. Inhibition of HOTAIR and EZH2 attenuated the luminal-like to basal-like transition in terms of gene expression and growth in MCF-7-TNR cells. Inhibition of p38 and SRC diminished HOTAIR expression and the basal-like phenotype in MCF-7-TNR cells. HOTAIR was robustly expressed in the native basal-like breast cancer cells and inhibition of HOTAIR reduced the basal-like gene expression and growth. Our findings suggest HOTAIR-mediated regulation of gene expression and growth associated with the basal-like phenotype of breast cancer cells. © 2014 Wiley Periodicals, Inc.
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Desmodeleganine, a new alkaloid from the leaves of Desmodium elegans as a potential monoamine oxidase inhibitor.
Fitoterapia
PUBLISHED: 08-04-2014
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Desmodeleganine (1), a new potential monoamine oxidase inhibitor, along with three known alkaloids, bufotenin (2), hydroxy-N, N-dimethyltryptamine N(12)-oxide (3), 2-(5-methoxy-1H-indol-3-yl)-N, and N-dimethylethylamine (4) were isolated from the leaves of Desmodium elegans. Their structures were elucidated by IR, MS, 1D and 2D NMR spectra. 1 showed strong monoamine oxidase inhibitory activity with IC50 value of 13.92 ± 1.5 ?M, when the IC50 value of iproniazid as a standard was 6.5 ± 0.5 ?M. The molecular modeling was also performed to explore the binding mode of compounds 1, 2 at the active site of MAO-A and MAO-B.
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[In vitro study of xylitol on the growth and acid production of Actinomyces viscosus].
Hua Xi Kou Qiang Yi Xue Za Zhi
PUBLISHED: 07-19-2014
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This research aimed to study the inhibitory effect of xylitol on the growth and acid production of Actinomyces viscosus (A. viscosus).
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Negative pressure cavitation-microwave assisted preparation of extract of Pyrola incarnata Fisch. rich in hyperin, 2'-O-galloylhyperin and chimaphilin and evaluation of its antioxidant activity.
Food Chem
PUBLISHED: 07-18-2014
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A novel and effective extraction method, namely negative pressure cavitation-microwave assisted extraction technique (NMAE), was developed for the preparation of extracts of Pyrola incarnata Fisch., which are rich in the main constituents hyperin, 2'-O-galloylhyperin and chimaphilin. Single factor experiments and Box-Behnken design (BBD) were combined with a response surface methodology to examine factors affecting extraction. Maximum extraction yields of hyperin, 2'-O-galloylhyperin and chimaphilin (1.339±0.029, 4.831±0.117 and 0.329±0.011mg/g, respectively) were achieved under the following optimised conditions: 700W microwave power, 50°C extraction temperature, 30:1mL/g liquid-solid ratio, -0.05MPa negative pressure, 55% ethanol concentration and 12min extraction time. First-order kinetics equation demonstrated that NMAE offered significant savings in extraction time, and enhancing extraction efficiency. Furthermore, NMAE extracts yielded excellent antioxidant activity (IC50 0.121mg/mL for DPPH 2.896mmol FeSO4/g DW FRAP).
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Genome-wide analysis of gestational gene-environment interactions in the developing kidney.
Physiol. Genomics
PUBLISHED: 07-08-2014
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The G protein-coupled bradykinin B2 receptor (Bdkrb2) plays an important role in regulation of blood pressure under conditions of excess salt intake. Our previous work has shown that Bdkrb2 also plays a developmental role since Bdkrb2(-/-) embryos, but not their wild-type or heterozygous littermates, are prone to renal dysgenesis in response to gestational high salt intake. Although impaired terminal differentiation and apoptosis are consistent findings in the Bdkrb2(-/-) mutant kidneys, the developmental pathways downstream of gene-environment interactions leading to the renal phenotype remain unknown. Here, we performed genome-wide transcriptional profiling on embryonic kidneys from salt-stressed Bdkrb2(+/+) and Bdkrb2(-/-) embryos. The results reveal significant alterations in key pathways regulating Wnt signaling, apoptosis, embryonic development, and cell-matrix interactions. In silico analysis reveal that nearly 12% of differentially regulated genes harbor one or more Pax2 DNA-binding sites in their promoter region. Further analysis shows that metanephric kidneys of salt-stressed Bdkrb2(-/-) have a significant downregulation of Pax2 gene expression. This was corroborated in Bdkrb2(-/-);Pax2(GFP+/tg) mice, demonstrating that Pax2 transcriptional activity is significantly repressed by gestational salt-Bdkrb2 interactions. We conclude that gestational gene (Bdkrb2) and environment (salt) interactions cooperate to impact gene expression programs in the developing kidney. Suppression of Pax2 likely contributes to the defects in epithelial survival, growth, and differentiation in salt-stressed BdkrB2(-/-) mice.
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Indoleacetic acid derivatives from the seeds of Ziziphus jujuba var. spinosa.
Fitoterapia
PUBLISHED: 07-05-2014
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A pair of diastereoisomers, the N-glycosylated derivatives of dioxindole-3-hydroxy-3-acetic acid 1-2, and their conjugates with flavonoids 3-8, was isolated from the seeds of Ziziphus jujuba var. spinosa. Their structures were elucidated by NMR spectroscopic analyses, and the absolute configurations were determined by circular dichroism method. Compounds 3-10 were evaluated for the antioxidant capacity, using the radical absorbance capacity (ORAC) assay.
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[Research progress in the study of brain microdialysis in glioma].
Yao Xue Xue Bao
PUBLISHED: 07-01-2014
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Glioma is the most common form of brain cancer. Despite recent advances in the treatment of solid tumors, there are few effective treatments for malignant gliomas due to its infiltrative nature. It has important significance to improve the treatment of glioma through in-depth understanding the intracerebral metabolic characteristics and pharmacokinetics of chemotherapeutics. Brain microdialysis (B-MD), an effective method to monitor central nervous system anticancer drug disposition, conditions of drugs through the blood-brain barrier, basic pathophysiologic metabolism, bioactive compounds and the changes of neurotransmitter in brain, provides the unique opportunity to allow the simultaneous determination of unbound concentrations of drugs in several tissues, and directly measure gliomas biochemistry continuously. B-MD has been able to monitor the change of brain drugs, metabolites and neurotransmitters, dynamic analysis of the drug concentration and pharmacological effect after administration, pharmacodynamic interaction between drugs, receptor mechanism of drug transport, as well as feedback information of internal environment. B-MD is expected to provide reference for clinical individual chemotherapy of glioma, but also provide powerful tools for the evaluation of new anticancer drugs in vivo. In this review, a comprehensive overview of B-MD for studies on glioma is elucidated with special emphasis on its application to neurochemistry and pharmacokinetic studies.
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Norsampsones A-D, four new decarbonyl polycyclic polyprenylated acylphloroglucinols from Hypericum sampsonii.
Org. Lett.
PUBLISHED: 06-16-2014
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Norsampsones A-D (1-4), four new decarbonyl polycyclic polyprenylated acylphloroglucinols, together with a new biogenetically related compound hypersampsone M (5), were isolated from the aerial parts of Hypericum sampsonii. Norsampsones A-D featured an unprecedented carbon skeleton with the loss of C-2 carbonyl in the phloroglucinol ring. All structures were determined by extensive NMR spectroscopic methods, ECD calculation, and single-crystal X-ray diffraction.
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Eremophilane-type sesquiterpenoids with diverse skeletons from Ligularia sagitta.
J. Nat. Prod.
PUBLISHED: 06-10-2014
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Five new highly oxygenated eremophilane-type sesquiterpenoids, possessing C19 (1 and 2), C15 (3 and 4), and C14 (8) skeletons, along with eight known eremophilenolides were obtained from the aerial parts of Ligularia sagitta. The absolute configuration of 1 was assigned by X-ray diffraction analysis and that of 3 by ECD spectroscopy. Compounds 1-10 were evaluated for their antibacterial activities against Staphyloccocus aureus, Bacillus subtilis, Escherichia coli, Bacillus cereus, and Erwinia carotovora. Compounds 4 and 5 displayed broad-spectrum inhibitory activity against these bacteria with MIC values of approximately 7.25 ?g/mL, followed by 3 and 6 with MIC values in the range of 23.0-125.0 ?g/mL. Compounds 3 and 8 showed mild activity against three human tumor cell lines (IC50 ? 13 ?M). Preliminary structure-activity relationships for these eremophilenolides are reported.
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[Inversion and spatial-temporal distribution analysis on PM5.0 inhalable particulate in Beijing].
Huan Jing Ke Xue
PUBLISHED: 05-13-2014
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Study on urban spatial characteristics of inhalable particulate and its influencing factors has an important practical significance for the development of more effective inhalable particulate pollution control policy. On the basis of the actual sampling and remote sensing data processing, a correlation model was established between the difference vegetation index (DVI) values of TM images and the measured values of the corresponding PM5.0 particulate matter, and PM5.0 distributions from 2008 to 2010 in Beijing were acquired by the use of inversion experiments and their accuracies were tested. Furthermore, the impact of NDBI and NDMI on PM5.0 was explored, as well as the spatial and temporal characteristics of inhalable particulate within the five rings of Beijing. The results showed that: (1) the PM5.0 inversion method using DVI was feasible, and the inversion accuracy was acceptable; (2) Overall, in 2008, PM5.0 particulate matter pollution was the lightest in the study area. The higher values of particle pollution were distributed between the southwest third ring road and southwest fourth ring road, as well as between the southeast third ring road and southeast fourth ring road, and the lower values of particle pollution were distributed around the northwest fifth ring road; (3) NDBI and NDMI had equal significant impact on inhalable particulate, which respectively showed significant negative correlation and positive correlation.
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[Association of interleukin-1? genetic polymorphisms with obstructive sleep apnea syndrome].
Zhongguo Yi Xue Ke Xue Yuan Xue Bao
PUBLISHED: 05-06-2014
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To investigate the association between interleukin(IL)-1? genetic polymorphisms and obstructive sleep apnea syndrome(OSAS).
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[Clinical epidemiology and histological characteristics of patients with lung cancer in West China Hospital of Sichuan University].
Sichuan Da Xue Xue Bao Yi Xue Ban
PUBLISHED: 04-23-2014
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To identify changes in patterns of primary bronchogenic carcinoma.
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The marine-derived fungal metabolite, terrein, inhibits cell proliferation and induces cell cycle arrest in human ovarian cancer cells.
Int. J. Mol. Med.
PUBLISHED: 04-07-2014
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The difficulties faced in the effective treatment of ovarian cancer are multifactorial, but are mainly associated with relapse and drug resistance. Cancer stem-like cells have been reported to be an important contributor to these hindering factors. In this study, we aimed to investigate the anticancer activities of a bioactive fungal metabolite, namely terrein, against the human epithelial ovarian cancer cell line, SKOV3, primary human ovarian cancer cells and ovarian cancer stem-like cells. Terrein was separated and purified from the fermentation metabolites of the marine sponge-derived fungus, Aspergillus terreus strain PF26. Its anticancer activities against ovarian cancer cells were investigated by cell proliferation assay, cell migration assay, cell apoptosis and cell cycle assays. The ovarian cancer stem-like cells were enriched and cultured in a serum-free in vitro suspension system. Terrein inhibited the proliferation of the ovarian cancer cells by inducing G2/M phase cell cycle arrest. The underlying mechanisms involved the suppression of the expression of LIN28, an important marker gene of stemness in ovarian cancer stem cells. Of note, our study also demonstrated the ability of terrein to inhibit the proliferation of ovarian cancer stem-like cells, in which the expression of LIN28 was also downregulated. Our findings reveal that terrein (produced by fermention) may prove to be a promising drug candidate for the treatment of ovarian cancer by inhibiting the proliferation of cancer stem-like cells.
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Chimaphilin induces apoptosis in human breast cancer MCF-7 cells through a ROS-mediated mitochondrial pathway.
Food Chem. Toxicol.
PUBLISHED: 03-21-2014
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Chimaphilin, 2,7-dimethyl-1,4-naphthoquinone, is extracted from pyrola [Passiflora incarnata Fisch.]. In this study, the anticancer activity and underlying mechanisms of chimaphilin toward human breast cancer MCF-7 cells are firstly investigated. Chimaphilin could inhibit the viability of MCF-7 cells in a concentration-dependent manner, and the IC50 value was 43.30?M for 24h. Chimaphilin markedly induced apoptosis through the investigation of characteristic apoptotic morphological changes, nuclear DNA fragmentation, annexin V-FITC/propidium iodide (PI) double staining. Flow cytometry assay revealed that chimaphilin triggered a significant generation of ROS and disruption of mitochondrial membrane potential. Additionally, western blotting assay showed that chimaphilin suppressed Bcl-2 level and enhanced Bad level, then activated caspase-9 and caspase-3, and further activated the poly ADP-ribose polymerase (PARP), finally induced cell apoptosis involving the mitochondrial pathway. Furthermore, free radical scavengers N-acetyl-L-cysteine (NAC) pretreatment test testified that chimaphilin could increase the generation of ROS, then induce cell apoptosis. In general, the present results demonstrated that chimaphilin induced apoptosis in human breast cancer MCF-7 cells via a ROS-mediated mitochondrial pathway.
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Liver Med23 ablation improves glucose and lipid metabolism through modulating FOXO1 activity.
Cell Res.
PUBLISHED: 03-18-2014
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Mediator complex is a molecular hub integrating signaling, transcription factors, and RNA polymerase II (RNAPII) machinery. Mediator MED23 is involved in adipogenesis and smooth muscle cell differentiation, suggesting its role in energy homeostasis. Here, through the generation and analysis of a liver-specific Med23-knockout mouse, we found that liver Med23 deletion improved glucose and lipid metabolism, as well as insulin responsiveness, and prevented diet-induced obesity. Remarkably, acute hepatic Med23 knockdown in db/db mice significantly improved the lipid profile and glucose tolerance. Mechanistically, MED23 participates in gluconeogenesis and cholesterol synthesis through modulating the transcriptional activity of FOXO1, a key metabolic transcription factor. Indeed, hepatic Med23 deletion impaired the Mediator and RNAPII recruitment and attenuated the expression of FOXO1 target genes. Moreover, this functional interaction between FOXO1 and MED23 is evolutionarily conserved, as the in vivo activities of dFOXO in larval fat body and in adult wing can be partially blocked by Med23 knockdown in Drosophila. Collectively, our data revealed Mediator MED23 as a novel regulator for energy homeostasis, suggesting potential therapeutic strategies against metabolic diseases.
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Development of a proficiency testing program for the HIV-1 BED incidence assay in China.
Sci Rep
PUBLISHED: 03-13-2014
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The HIV-1 BED incidence assay was adopted in China in 2005 for HIV-1 incidence surveillance. A proficiency testing (PT) program was established in 2006 to provide quality assurance services. The BED PT program consisted of two components, an international program provided by the U.S. Centers for Disease Control and Prevention from 2006 and a domestic program started by the National HIV/HCV Reference Laboratory in 2011. Each PT panel consisted of eight coded specimens distributed to participating laboratories semi-annually, and testing results were collected and analyzed. The number of participating laboratories increased progressively from 2006 to 2012. The Chinese HIV-1 incidence laboratory network performed satisfactorily both in international and domestic PT programs. We also demonstrated that the BED assay was highly reproducible among participating laboratories. Our success and lessons learned can be readily replicated in other countries or regions contemplating the establishment of a PT program for assay-based HIV incidence estimation.
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Sodium arsenite induces ROS-dependent autophagic cell death in pancreatic ?-cells.
Food Chem. Toxicol.
PUBLISHED: 03-12-2014
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Inorganic arsenic is a worldwide environmental pollutant. Inorganic arsenic's positive relationship with the incidence of type 2 diabetes mellitus arouses concerns associated with its etiology in diabetes among the general human population. In this study, the inhibitor of autophagosome formation, 3-methyladenine, protected the cells against sodium arsenite cytotoxicity, and the autophagy stimulator rapamycin further decreased the cell viability of sodium arsenite-treated INS-1 cells. These finding suggested the hypothesis that autophagic cell death contributed to sodium arsenite-induced cytotoxicity in INS-1 cells. Sodium arsenite increased the autophagosome-positive puncta in INS-1 cells observed under a fluorescence microscope, and this effect was confirmed by the elevated LC3-II levels detected through Western blot. The LC3 turnover assay indicated that the accumulation of autophagosomes in the arsenite-treated INS-1 cells was due to increased formation rather than impaired degradation. The pretreatment of INS-1 cells with the ROS inhibitor NAC reduced autophagosome formation and reversed the sodium arsenite cytotoxicity, indicating that sodium arsenite-induced autophagic cell death was ROS-dependent. In summary, the precise molecular mechanisms through which arsenic is related to diabetes have not been completely elucidated, but the ROS-dependent autophagic cell death of pancreatic ?-cells described in this study may help to elucidate the underlying mechanism.
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[Relationship between female dyslipidemia and polymorphism of suppressor of cytokine signaling-3 in Xinjiang Uygur population].
Zhongguo Yi Xue Ke Xue Yuan Xue Bao
PUBLISHED: 03-04-2014
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To explore whether the polymorphism of suppressor of cytokine signaling-3(SOCS-3)and dyslipidemia are correlated in Uygur females.
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Surgical treatment of poor grade middle cerebral artery aneurysms associated with large sylvian hematomas following prophylactic hinged craniectomy.
J. Huazhong Univ. Sci. Technol. Med. Sci.
PUBLISHED: 02-28-2014
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The clinical characteristics of patients who presented in poor clinical grade due to ruptured middle cerebral artery aneurysms (MCAAs) associated with large sylvian hematomas (SylH) were analyzed and an ingenious designed prophylactic hinged craniectomy was introduced. Twenty-eight patients were graded into Hunt-Hess grades IV-V and emergency standard micro-neurosurgeries (aneurysm clipping, hematoma evacuation and prophylactic hinged craniectomy) were performed, and their clinical data were retrospectively analyzed. 46.43% of the patients reached encouraged favorable outcomes on discharge. The favorable outcome group and the poor outcome group significantly differed in terms of patients' anisocoria, Hunt-Hess grade before surgery, extent of the midline shift and time to the surgery after bleeding (P<0.05). There were no significant differences in age, sex, volume and location of the hematoma, size of aneurysm between the favorable and poor groups (P>0.05). However, ingenious designed prophylactic hinged craniectomy efficiently reduced the patients' intracranial pressure (ICP) after surgery. It was suggested that preoperative conditions such as Hunt-Hess grading, extent of the midline shift and the occurrence of cerebral hernia affect the prognosis of patients, but time to the surgery after bleeding and prophylactic hinged craniectomy are of significant importance for optimizing the prognosis of MCAA patients presenting with large SylH.
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Extracellular-regulated kinase 2 is activated by the enhancement of hinge flexibility.
J. Mol. Biol.
PUBLISHED: 02-05-2014
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Protein motions underlie conformational and entropic contributions to enzyme catalysis; however, relatively little is known about the ways in which this occurs. Studies of the mitogen-activated protein kinase ERK2 (extracellular-regulated protein kinase 2) by hydrogen-exchange mass spectrometry suggest that activation enhances backbone flexibility at the linker between N- and C-terminal domains while altering nucleotide binding mode. Here, we address the hypothesis that enhanced backbone flexibility within the hinge region facilitates kinase activation. We show that hinge mutations enhancing flexibility promote changes in the nucleotide binding mode consistent with domain movement, without requiring phosphorylation. They also lead to the activation of monophosphorylated ERK2, a form that is normally inactive. The hinge mutations bypass the need for pTyr but not pThr, suggesting that Tyr phosphorylation controls hinge motions. In agreement, monophosphorylation of pTyr enhances both hinge flexibility and nucleotide binding mode, measured by hydrogen-exchange mass spectrometry. Our findings demonstrate that regulated protein motions underlie kinase activation. Our working model is that constraints to domain movement in ERK2 are overcome by phosphorylation at pTyr, which increases hinge dynamics to promote the active conformation of the catalytic site.
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Phosphorylation releases constraints to domain motion in ERK2.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 02-03-2014
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Protein motions control enzyme catalysis through mechanisms that are incompletely understood. Here NMR (13)C relaxation dispersion experiments were used to monitor changes in side-chain motions that occur in response to activation by phosphorylation of the MAP kinase ERK2. NMR data for the methyl side chains on Ile, Leu, and Val residues showed changes in conformational exchange dynamics in the microsecond-to-millisecond time regime between the different activity states of ERK2. In inactive, unphosphorylated ERK2, localized conformational exchange was observed among methyl side chains, with little evidence for coupling between residues. Upon dual phosphorylation by MAP kinase kinase 1, the dynamics of assigned methyls in ERK2 were altered throughout the conserved kinase core, including many residues in the catalytic pocket. The majority of residues in active ERK2 fit to a single conformational exchange process, with kex ? 300 s(-1) (kAB ? 240 s(-1)/kBA ? 60 s(-1)) and pA/pB ? 20%/80%, suggesting global domain motions involving interconversion between two states. A mutant of ERK2, engineered to enhance conformational mobility at the hinge region linking the N- and C-terminal domains, also induced two-state conformational exchange throughout the kinase core, with exchange properties of kex ? 500 s(-1) (kAB ? 15 s(-1)/kBA ? 485 s(-1)) and pA/pB ? 97%/3%. Thus, phosphorylation and activation of ERK2 lead to a dramatic shift in conformational exchange dynamics, likely through release of constraints at the hinge.
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Alistonitrine A, a caged monoterpene indole alkaloid from Alstonia scholaris.
Org. Lett.
PUBLISHED: 02-03-2014
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Alistonitrine A, a new monoterpene indole alkaloid incorporating a third nitrogen atom, was isolated from the leaves of Alstonia scholaris and found to possess an unprecedented caged skeleton with a unique 6/5/6/5/5/6 ring system. Its structure and absolute configuration were established by extensive spectroscopic analyses and electron circular dichroism calculations. A plausible biogenetic pathway has been proposed for the biosynthesis of alistonitrine A from picrinine.
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Reconstituting the epidemic history of mono lineage of HIV-1 CRF01_AE in Guizhou province, Southern China.
Infect. Genet. Evol.
PUBLISHED: 01-27-2014
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Guizhou province, located between border provinces and Central province of China, plays a crucial role in the transmission of HIV-1, implying it is important to monitor the epidemic of HIV-1 in this region. Available HIV-1 infected patients' plasma (n=78) were collected from Tongren city, Eastern Guizhou. Full-length gag, partial pol and env gene sequences were amplified and analyzed using phylogenetic, recombinant and Bayesian molecular clock approaches. Phylogenetic and recombinant analyses showed that CRF01_AE predominated among injecting drug users and heterosexuals in Tongren city with 85.9% proportion, it was followed by B' (5.1%), CRF07_BC (3.8%), CRF08_BC (3.8%), and B (1.3%). Moreover, 98.5% of CRF01_AE strains belonged to the distinct lineage CRF01_AE-v previously found in Guangxi province. To infer the most probable origin of CRF01_AE-v in Guizhou province, we download all available full length of CRF01_AE gag, pol and env gene region sequences from China in Los Alamos HIV sequence database. Phylodynamic and phylogeographic analyses revealed that the expanding CRF01_AE-v epidemic in Guizhou province was the result of local epidemic driven by multiple independent introductions of CRF01_AE-v strains from Guangxi province in early 2000s. High prevalence of CRF01_AE in Guizhou province may bridge the epidemic to Central China. It provides a new insight for the understanding of HIV-1 epidemic in Guizhou province and makes the evolutionary history of CRF01_AE in China more intact.
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Estrogen-provided cardiac protection following burn trauma is mediated through a reduction in mitochondria-derived DAMPs.
Am. J. Physiol. Heart Circ. Physiol.
PUBLISHED: 01-24-2014
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Mitochondria-derived danger-associated molecular patterns (DAMPs) play important roles in sterile inflammation after acute injuries. This study was designed to test the hypothesis that 17?-estradiol protects the heart via suppressing myocardial mitochondrial DAMPs after burn injury using an animal model. Sprague-Dawley rats were given a third-degree scald burn comprising 40% total body surface area (TBSA). 17?-Estradiol, 0.5 mg/kg, or control vehicle was administered subcutaneously 15 min following burn. The heart was harvested 24 h postburn. Estradiol showed significant inhibition on the productivity of H2O2 and oxidation of lipid molecules in the mitochondria. Estradiol increased mitochondrial antioxidant defense via enhancing the activities and expression of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Estradiol also protected mitochondrial respiratory function and structural integrity. In parallel, estradiol remarkably decreased burn-induced release of mitochondrial cytochrome c and mitochondrial DNA (mtDNA) into cytoplasm. Further, estradiol inhibited myocardial apoptosis, shown by its suppression on DNA laddering and downregulation of caspase 1 and caspase 3. Estradiol's anti-inflammatory effect was demonstrated by reduction in systemic and cardiac cytokines (TNF-?, IL-1?, and IL-6), decrease in NF-?B activation, and attenuation of the expression of inflammasome component ASC in the heart of burned rats. Estradiol-provided cardiac protection was shown by reduction in myocardial injury marker troponin-I, amendment of heart morphology, and improvement of cardiac contractility after burn injury. Together, these data suggest that postburn administration of 17?-estradiol protects the heart via an effective control over the generation of mitochondrial DAMPs (mtROS, cytochrome c, and mtDNA) that incite cardiac apoptosis and inflammation.
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Ultrafast all-optical graphene modulator.
Nano Lett.
PUBLISHED: 01-13-2014
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Graphene is an optical material of unusual characteristics because of its linearly dispersive conduction and valence bands and the strong interband transitions. It allows broadband light-matter interactions with ultrafast responses and can be readily pasted to surfaces of functional structures for photonic and optoelectronic applications. Recently, graphene-based optical modulators have been demonstrated with electrical tuning of the Fermi level of graphene. Their operation bandwidth, however, was limited to about 1 GHz by the response of the driving electrical circuit. Clearly, this can be improved by an all-optical approach. Here, we show that a graphene-clad microfiber all-optical modulator can achieve a modulation depth of 38% and a response time of ? 2.2 ps, limited only by the intrinsic carrier relaxation time of graphene. This modulator is compatible with current high-speed fiber-optic communication networks and may open the door to meet future demand of ultrafast optical signal processing.
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The prognostic implications of microvascular density and lymphatic vessel density in esophageal squamous cell carcinoma: Comparative analysis between the traditional whole sections and the tissue microarray.
Acta Histochem.
PUBLISHED: 01-09-2014
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Focal distribution of microvascular and lymphatic vessels is a critical issue in cancer, and is measured by tissue microarray (TMA) construction from paraffin-embedded surgically obtained tissues, a process that may not accurately reflect true focal distribution. The aim of this study was to assess the concordance of microvascular density (MVD) and lymphatic vessel density (LVD) in TMAs with corresponding whole sections, and to correlate the MVD or LVD with clinicopathological parameters in 124 cases of esophageal squamous cell carcinoma (ESCC). MVD, determined by CD105 immunohistochemistry of whole sections, was strongly associated with lymph node metastasis (p=0.000) and pTNM stage (p=0.001). Kaplan-Meier survival analysis showed that increasing CD105 microvessel count correlated with decreasing survival (p<0.001). The same result was acquired when MVD was calculated from tissue microarrays. Analysis of continuous data showed a highly significant correlation between whole sections and TMA data (Pearson r=0.522, p<0.001). Increasing LVD, as determined by D2-40 immunohistochemistry of whole sections, correlated with decreasing survival, but this relationship was undetectable using TMAs. In conclusion, we demonstrate that for the selected endothelial markers, TMAs can provide a realistic and reliable estimate of the extent of MVD, but not LVD in ESCC samples.
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Mdm2 is required for maintenance of the nephrogenic niche.
Dev. Biol.
PUBLISHED: 01-08-2014
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The balance between nephron progenitor cell (NPC) renewal, survival and differentiation ultimately determines nephron endowment and thus susceptibile to chronic kidney disease and hypertension. Embryos lacking the p53-E3 ubiquitin ligase, Murine double minute 2 (Mdm2), die secondary to p53-mediated apoptosis and growth arrest, demonstrating the absolute requirement of Mdm2 in embryogenesis. Although Mdm2 is required in the maintenance of hematopoietic stem cells, its role in renewal and differentiation of stem/progenitor cells during kidney organogenesis is not well defined. Here we examine the role of the Mdm2-p53 pathway in NPC renewal and fate in mice. The Six2-GFP::Cre(tg/+) mediated inactivation of Mdm2 in the NPC (NPC(Mdm)2(-/-)) results in perinatal lethality. NPC(Mdm)2(-/-) neonates have hypo-dysplastic kidneys, patchy depletion of the nephrogenic zone and pockets of superficially placed, ectopic, well-differentiated proximal tubules. NPC(Mdm2-/-) metanephroi exhibit thinning of the progenitor GFP(+)/Six2(+) population and a marked reduction or loss of progenitor markers Amphiphysin, Cited1, Sall1 and Pax2. This is accompanied by aberrant accumulation of phospho-?H2AX and p53, and elevated apoptosis together with reduced cell proliferation. E13.5-E15.5 NPC(Mdm2-/-) kidneys show reduced expression of Eya1, Pax2 and Bmp7 while the few surviving nephron precursors maintain expression of Wnt4, Lhx1, Pax2, and Pax8. Lineage fate analysis and section immunofluorescence revealed that NPC(Mdm2-/-) kidneys have severely reduced renal parenchyma embedded in an expanded stroma. Six2-GFP::Cre(tg/+); Mdm2(f/f) mice bred into a p53 null background ensures survival of the GFP-positive, self-renewing progenitor mesenchyme and therefore restores normal renal development and postnatal survival of mice. In conclusion, the Mdm2-p53 pathway is essential to the maintenance of the nephron progenitor niche.
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Perfluorooctane sulfonate blocked autophagy flux and induced lysosome membrane permeabilization in HepG2 cells.
Food Chem. Toxicol.
PUBLISHED: 01-07-2014
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Perfluorooctane sulfonate (PFOS) is an emerging persistent organic pollutant widely distributed in the environment, wildlife and human. In this study, as observed under the transmission electron microscope, PFOS increased autophagosome numbers in HepG2 cells, and it was confirmed by elevated LC3-II levels in Western blot analysis. PFOS increased P62 level and chloroquine failed to further increase the expression of LC3-II after PFOS treatment, indicating that the accumulation of autophagosome was due to impaired degradation rather than increased formation. With acridine orange staining, we found PFOS caused lysosomal membrane permeabilization (LMP). In this study, autophasome formation inhibitor 3-methyladenine protected cells against PFOS toxicity, autophagy stimulator rapamycin further decreased cell viability and increased LDH release, cathepsin inhibitor did not influence cell viability of PFOS-treated HepG2 cells significantly. These further supported the notion that autophagic cell death contributed to PFOS-induced hepatotoxicity. In summary, the data of the present study revealed that PFOS induced LMP and consequent blockage of autophagy flux, leading to an excessive accumulation of the autophagosomes and turning autophagy into a destructive process eventually. This finding will provide clues for effective prevention and treatment of PFOS-induced hepatic disease.
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Effects of histone deacetylase inhibitors on the early development of bovine androgenetic embryos.
Cell Reprogram
PUBLISHED: 01-04-2014
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Histone acetylation is one of the most important posttranslational modifications that contribute to transcriptional initiation and chromatin remodeling. In our previous study, we enhanced sperm chromatin remodeling within the bovine sperm injection-derived androgenentic (SpI-AG) embryos by sperm pretreatment, and thereby improved their early developmental competence. In this study, we found that blastocyst development of SpI-AG embryos could be elevated by the histone deacetylase inhibitor (HDACi). First, we optimized the efficacy of two histone deacetylase inhibitors [trichostatin A (TSA) and Scriptaid (SCR)] in a dose (0, 5, 10, 20, 50, and 100?nM for TSA; 0, 50, 100, 200, 300, and 500 nM for SCR, respectively) and time-dependent (0, 10, 15, 20, and 25?h) manner on the developmental capacity of these embryos. Furthermore, we quantitatively assessed the alterations in histone H3 and H4 overall acetylation levels and blastocyst quality of SpI-AG embryos by immunofluorescence staining. We found a significantly improved morula and blastocyst development rate of SpI-AG embryos at a mild dose of TSA (20 nM) or SCR (200?nM) for 15?h after embryo activation. Furthermore, both HDACi noticeably increased the levels of acetylated histone H3 and H4 in SpI-AG blastocyst embryos, whereas, SCR treatment improved the quality of blastocysts when compared with control group. In conclusion, HDACi is beneficial for early development of bovine SpI-AG embryos and can be used to improve the efficiency of its in vitro production.
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Genetic redundancy, proximity, and functionality of lspA, the target of antibiotic TA, in the Myxococcus xanthus producer strain.
J. Bacteriol.
PUBLISHED: 01-03-2014
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We recently showed that type II signal peptidase (SPaseII) encoded by lspA is the target of an antibiotic called TA (myxovirescin), which is made by Myxococcus xanthus. SPaseII cleaves the signal peptide during bacterial lipoprotein processing. Bacteria typically contain one lspA gene; however, strikingly, the M. xanthus DK1622 genome contains four (lspA1 to lspA4). Since two of these genes, lspA3 and lspA4, are located in the giant TA biosynthetic gene cluster, we hypothesized they may play a role in TA resistance. To investigate the functions of the four M. xanthus lspA (lspA(Mx)) genes, we conducted sequence comparisons and found that they contained nearly all the conserved residues characteristic of SPaseII family members. Genetic studies found that an Escherichia coli ?lspA mutation could be complemented by any of the lspA(Mx) genes in an lpp mutant background, but not in an E. coli lpp(+) background. Because Lpp is the most abundant E. coli lipoprotein, these results suggest the M. xanthus proteins do not function as efficiently as the host enzyme. In E. coli, overexpression of each of the LspA(Mx) proteins conferred TA and globomycin resistance, although LspA3 conferred the highest degree of resistance. In M. xanthus, each lspA(Mx) gene could be deleted and was therefore dispensable for growth. However, lspA3 or lspA4 deletion mutants each exhibited a tan phase variation bias, which likely accounts for their reduced-swarming and delayed-development phenotypes. In summary, we propose that all four LspA(Mx) proteins function as SPaseIIs and that LspA3 and LspA4 might also have roles in TA resistance and regulation, respectively.
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Melatonin enhances the anti-tumor effect of fisetin by inhibiting COX-2/iNOS and NF-?B/p300 signaling pathways.
PLoS ONE
PUBLISHED: 01-01-2014
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Melatonin is a hormone identified in plants and pineal glands of mammals and possesses diverse physiological functions. Fisetin is a bio-flavonoid widely found in plants and exerts antitumor activity in several types of human cancers. However, the combinational effect of melatonin and fisetin on antitumor activity, especially in melanoma treatment, remains unclear. Here, we tested the hypothesis that melatonin could enhance the antitumor activity of fisetin in melanoma cells and identified the underlying molecular mechanisms. The combinational treatment of melanoma cells with fisetin and melatonin significantly enhanced the inhibitions of cell viability, cell migration and clone formation, and the induction of apoptosis when compared with the treatment of fisetin alone. Moreover, such enhancement of antitumor effect by melatonin was found to be mediated through the modulation of the multiply signaling pathways in melanoma cells. The combinational treatment of fisetin with melatonin increased the cleavage of PARP proteins, triggered more release of cytochrome-c from the mitochondrial inter-membrane, enhanced the inhibition of COX-2 and iNOS expression, repressed the nuclear localization of p300 and NF-?B proteins, and abrogated the binding of NF-?B on COX-2 promoter. Thus, these results demonstrated that melatonin potentiated the anti-tumor effect of fisetin in melanoma cells by activating cytochrome-c-dependent apoptotic pathway and inhibiting COX-2/iNOS and NF-?B/p300 signaling pathways, and our study suggests the potential of such a combinational treatment of natural products in melanoma therapy.
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Mouse endometrial stromal cells and progesterone inhibit the activation and regulate the differentiation and antibody secretion of mouse B cells.
Int J Clin Exp Pathol
PUBLISHED: 01-01-2014
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The regulation mechanism for the B cells in the female reproductive tract (FRT) is unclear now. The aim of this study was to analysis the effect of progesterone and mouse endometrium stromal cells (ESCs) on B cells and explore it roles in modulating B cells-mediated immune responses. We primary isolated mouse ESCs from endometrium of BALB/c mice and B cells from spleen cells of BALB/c mice, and then constructed these two kind of cells co-culture system, and treated with or without progesterone. We found that both treatment with progesterone and co-culture with ESCs reduced the expression of co-stimulatory molecules CD80 and CD86 on mouse B cells from spleen cells. In addition, the expression of CD138 (syndecan-1) on B cells was increased after co-culture with ESCs, however, progesterone could partly reduce this effect. Unlike progesterone, ESCs alone promoted the proliferation and stimulated the secretion level of antibodies IgG and IgA of B cells. Our current results progesterone and ESCs could inhibit the activation of B cells through deceasing CD80 and CD86 expression, regulated the differentiation status of B cells by up-regulating the expression of CD138 together, and might further inhibit the antigen presentation function of B cells, which is beneficial to the establishment of fertilization and pregnancy. In addition, ESCs also promoted the proliferation and antibody secretion, which might participate in the resisting infections during non pregnancy and pregnancy.
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[Association study of PRDM16 gene polymorphisms with essential hypertension in Xinjiang Uygur population].
Zhonghua Yi Xue Yi Chuan Xue Za Zhi
PUBLISHED: 12-12-2013
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To assess the association of polymorphisms of PR domain containing 16 gene (PRDM16) with essential hypertension in ethnic Uygur population from Xinjiang, China.
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Sperm capacitation combined with removal of the sperm acrosome and plasma membrane enhances paternal nucleus remodelling and early development of bovine androgenetic embryos.
Reprod. Fertil. Dev.
PUBLISHED: 11-10-2013
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The androgenetic embryo is a useful model for functional analysis of the paternal genome during embryogenesis. However, few studies have focused on the factors involved in the suppressed developmental competence of such embryos or why sperm cloning-derived androgenetic embryos fail to develop beyond the morula stage in large domestic animals. To overcome this developmental failure, we tried to improve sperm decondensation, as well as to enhance embryonic development by sperm capacitation and removal of the acrosome and plasma membrane before injection of the spermatozoa. Before injection of the spermatozoa, we quantified the effects of sperm capacitation combined with sperm pretreatment on the acrosome and plasma membrane status. We also evaluated sperm decondensation potential, sperm viability and chromatin integrity. Immunostaining data showed that the sperm acrosome and plasma membrane could be more efficiently removed after capacitation. Dithiothreitol-induced sperm decondensation potential was improved with capacitation and removal of the acrosome and plasma membrane. Although most spermatozoa lost viability after pretreatment, their chromatin remained integrated. The patterns of paternal chromatin remodelling within uncleaved androgenetic embryos and the nucleus morphology of cleaved embryos indicated that capacitation combined with membrane disruption could make injected spermatozoa decondense synchronously not only with each other, but also with the developmental pace of the ooplasm. We successfully produced androgenetic blastocysts, and efficiency increased with sperm pretreatment. In conclusion, sperm decondensation and the early development of androgenetic embryos were enhanced with sperm capacitation and removal of the acrosome and plasma membrane prior to sperm injection.
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Tentative identification of sex-specific antibodies and their application for screening bovine sperm proteins for sex-specificity.
Mol. Biol. Rep.
PUBLISHED: 10-30-2013
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Our previous studies indicated that a purified rabbit antiserum against X-sperm contained sex-specific antibodies (SSAbs) which preferentially bound to sex-sorted X-sperm. The specificity of sex-specific antiserum was initially demonstrated using flow cytometry only, which resulted in uncertainty. In this study, the putative SSAbs against bovine X-sperm (XSSAb) were produced by a series of immunological approaches, and the effectiveness of separation of sperm using putative XSSAb was validated. Subsequently, the XSSAb was used to immunoprecipitate sex-specific proteins (SSPs) in bovine sperm, followed by two-dimensional gel electrophoresis. The results showed 7.6, 15.2 and 52.1 % of sex-sorted Y-sperm, sex-sorted X-sperm and unsorted sperm were recognized by the neutralized rabbit antisera against X-sperm, respectively. Also the purity of separation of sperm using putative XSSAb reached 74.3 % when the immunologically separated sperm were injected into oocytes. In addition, three candidate SSP sports about 30 kDa were captured by the XSSAb. Our results confirmed that the putative XSSAb contained SSAbs, and implied that these three protein sports might be SSPs in bovine X-sperm. This provides a potentially more efficient method for sorting sperm and lays a foundation for future search for SSPs.
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Hybrid photon-plasmon nanowire lasers.
Nano Lett.
PUBLISHED: 10-21-2013
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Metallic and plasmonic nanolasers have attracted growing interest recently. Plasmonic lasers demonstrated so far operate in hybrid photon-plasmon modes in transverse dimensions, rendering it impossible to separate photonic from plasmonic components. Thus only the far-field photonic component can be measured and utilized directly. But spatially separated plasmon modes are highly desired for applications including high-efficiency coupling of single-photon emitters and ultrasensitivity optical sensing. Here, we report a nanowire (NW) laser that offers subdiffraction-limited beam size and spatially separated plasmon cavity modes. By near-field coupling a high-gain CdSe NW and a 100 nm diameter Ag NW, we demonstrate a hybrid photon-plasmon laser operating at 723 nm wavelength at room temperature, with a plasmon mode area of 0.008?(2). This device simultaneously provides spatially separated photonic far-field output and highly localized coherent plasmon modes, which may open up new avenues in the fields of integrated nanophotonic circuits, biosensing, and quantum information processing.
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Discovery of a selective NaV1.7 inhibitor from centipede venom with analgesic efficacy exceeding morphine in rodent pain models.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 09-30-2013
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Loss-of-function mutations in the human voltage-gated sodium channel NaV1.7 result in a congenital indifference to pain. Selective inhibitors of NaV1.7 are therefore likely to be powerful analgesics for treating a broad range of pain conditions. Herein we describe the identification of µ-SLPTX-Ssm6a, a unique 46-residue peptide from centipede venom that potently inhibits NaV1.7 with an IC50 of ?25 nM. µ-SLPTX-Ssm6a has more than 150-fold selectivity for NaV1.7 over all other human NaV subtypes, with the exception of NaV1.2, for which the selectivity is 32-fold. µ-SLPTX-Ssm6a contains three disulfide bonds with a unique connectivity pattern, and it has no significant sequence homology with any previously characterized peptide or protein. µ-SLPTX-Ssm6a proved to be a more potent analgesic than morphine in a rodent model of chemical-induced pain, and it was equipotent with morphine in rodent models of thermal and acid-induced pain. This study establishes µ-SPTX-Ssm6a as a promising lead molecule for the development of novel analgesics targeting NaV1.7, which might be suitable for treating a wide range of human pain pathologies.
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New clerodane diterpenoid glycosides from the aerial parts of Nannoglottis carpesioides.
Fitoterapia
PUBLISHED: 09-11-2013
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Three new clerodane diterpenoid glycosides with l-arabinose (1-3), together with ten known compounds including phytol-type diterpenes; cycloartane-type, ursane-type, and oleanane-type triterpenes, were isolated from the aerial parts of Nannoglottis carpesioides which a Chinese endemic genus. The structures of the new compounds 1-3 were identified based on chemical and spectroscopic studies, including one- and two-dimensional NMR, HRESIMS, UV, and IR results. Their absolute configurations were determined by the application of theory calculations of optical rotation, which were compared with the experimental data. New aglycone 1a and l-arabinose were obtained by acid hydrolysis of 1 and GC-MS analysis. The cytotoxicities of some isolated compounds against a panel of human cancer cell lines were evaluated by the MTT assay. Clerodane diterpenoides are the characteristic chemical constituents and may be used as chemical markers of the genus Nannoglottis.
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[Quality survey of different species of clematidis radix et rhizoma].
Zhongguo Zhong Yao Za Zhi
PUBLISHED: 08-16-2013
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Quality survey of different species of Clematidis Radix et Rhizoma was made by determining the content of hederagenin and oleanolic acid from Clematidis Radix et Rhizoma. The result showed that only a few samples of Clematis chinensis met the quality standard for Clematidis Radix et Rhizoma in Chinese Pharmacopoeia 2010 Edition.
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[Preparation and optical properties of MgAl2O4/Ce:YAG transparent ceramics].
Guang Pu Xue Yu Guang Pu Fen Xi
PUBLISHED: 08-03-2013
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High-purity ultrafine MgAl2O4 powder was synthesized by metal-alkoxide method and calcining for 2-4 h. And then MgAl2O4/Ce:YAG transparent ceramics were fabricated by hot-pressed sintering and hot isostatic pressed sintering technique with YAG:Ce powder and MgAl2O4 powder. The transparent ceramics were characterized by XRD, SEM, EDS and fluorescence spectrometer, respectively. The results show that the crystal phase of the transparent ceramic was composed of MgAl2O4 and YAG,and the YAG phase dispersed well in the matrix of MgAl2O4. The excitation spectra had a weak band at 345 nm and a strong band at 475 nm. The broad emission peaks at about 533 nm were attributed to 5d-->4f transition of Ce3+ ions. Decay curves for the fluorescence of MgAl2O4/Ce:YAG transparent ceramic test show that the lifetime of the Ce:YAG glass ceramic was 59.74 ns. All results show that MgAl2O4/Ce:YAG transparent ceramic may be a promising fluorescent material for white LED applications.
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Association between TLR4 polymorphism and periodontitis susceptibility: a meta-analysis.
Crit. Rev. Eukaryot. Gene Expr.
PUBLISHED: 07-25-2013
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TLR4 has been implicated in periodontal disease, but the association between the TLR4 Asp299Gly and Thr399Ile polymorphisms and the risk of periodontal disease remains unclear. Therefore, the aim of this study was to investigate the association between the TLR4 Asp299Gly and Thr399Ile polymorphism and periodontal disease. A search of electronic databases identified previous studies evaluating the association of the polymorphisms of TLR4 and periodontitis risk. The association was evaluated by odds ratio (OR) and its 95% confidence interval (CI). The results showed that TLR4 Asp299Gly and Thr399Ile were not associated with a significant risk of periodontitis (OR = 0.96, 95% CI = 0.80-1.16 for G versus A; OR = 1.39, 95% CI = 0.82-2.36 for AG/GG versus AA; OR = 1.05, 95% CI = 0.52-2.15 for T versus C; OR = 0.76, 95% CI = 0.55-1.04 for CT/TT versus CC). In the stratified analyses, there was no significantly increased risk for the studies of chronic periodontitis and aggressive periodontitis. Our meta-analysis revealed that the two common TLR4 polymorphisms, Asp299Gly and Thr399Ile, have no association with the likelihood of periodontitis. In a subgroup analysis by ethnicity and periodontitis type, the results also did not show any association. However, there was a significant increased risk for periodontitis in recessive models of Asp299Gly. The effect of genetic networks and their mutual interactions in the TLR4 signaling pathway on periodontitis susceptibility needs further study.
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Overnutrition stimulates intestinal epithelium proliferation through ?-catenin signaling in obese mice.
Diabetes
PUBLISHED: 07-24-2013
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Obesity is a major risk factor for type 2 diabetes and cardiovascular diseases. And overnutrition is a leading cause of obesity. After most nutrients are ingested, they are absorbed in the small intestine. Signals from ?-catenin are essential to maintain development of the small intestine and homeostasis. In this study, we used a hyperphagia db/db obese mouse model and a high-fat diet (HFD)-induced obesity mouse model to investigate the effects of overnutrition on intestinal function and ?-catenin signaling. The ?-catenin protein was upregulated along with inactivation of glycogen synthase kinase (GSK)-3? in the intestines of both db/db and HFD mice. Proliferation of intestinal epithelial stem cells, villi length, nutrient absorption, and body weight also increased in both models. These changes were reversed by caloric restriction in db/db mice and by ?-catenin inhibitor JW55 (a small molecule that increases ?-catenin degradation) in HFD mice. Parallel, in vitro experiments showed that ?-catenin accumulation and cell proliferation stimulated by glucose were blocked by the ?-catenin inhibitor FH535. And the GSK-3 inhibitor CHIR98014 in an intestinal epithelial cell line increased ?-catenin accumulation and cyclin D1 expression. These results suggested that, besides contribution to intestinal development and homeostasis, GSK-3?/?-catenin signaling plays a central role in intestinal morphological and functional changes in response to overnutrition. Manipulating the GSK-3?/?-catenin signaling pathway in intestinal epithelium might become a therapeutic intervention for obesity induced by overnutrition.
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The viscous characterization of hydroxyethyl starch (HES) plasma volume expanders in a non-Newtonian blood analog.
Biorheology
PUBLISHED: 07-19-2013
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Although information pertaining to the viscous characterization of HES 130/0.4 Voluven® and HES 260/0.45 Pentaspan® is available, quantification is limited to 100% concentrations. We focus here on the quantification of their viscous behavior along with HES 130/0.4 Volulyte® in a shear thinning non-Newtonian blood analog of aqueous xanthan gum and glycerol. Dynamic viscosities of multiple batches of HES fluids were measured through capillary viscometry. The viscous behavior of 100%, 25% and 12.5% concentrations were then measured through a closed flow loop across physiologically relevant flow rates. Measured viscosities were 2.57 millipascal second (mPa·s) 6.52 mPa·s and 2.48 mPa·s for HES 130/0.4 Voluven®, HES 260/0.45 and HES 130/0.4 Volulyte®, respectively. Pipe flow analysis found that all HES fluids displayed Newtonian behavior at 100% concentrations. 25% concentrations of both HES 130/0.4 fluids decreased analog viscosity 23%-29% at a flow rate of 1.0 ml/s and 16%-21% at a flow rate of 22.5 ml/s. At a flow rate of 22.5 ml/s, 25% and 12.5% concentrations of HES 260/0.45 resulted in analog viscosity changes of 3.9%-4.5%. Capillary viscosity reductions of approximately 7% and 14.5% in HES 130/0.4 Voluven® and HES 260/0.45 suggest changes in molecular composition to batches previously measured. Maintenance of analog viscosity suggests that HES 260/0.45 would be suitable as a high viscosity plasma expander in extreme hemodilution through preservation of microcirculatory function and wall shear stress (WSS).
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Histone signature of metanephric mesenchyme cell lines.
Epigenetics
PUBLISHED: 07-18-2013
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The metanephric mesenchyme (MM) gives rise to nephrons, the filtering units of the mature kidney. The MM is composed of uninduced (Six2(high)/Lhx1(low)) and induced (Wnt-stimulated, Six2(low)/Lhx1(high)) cells. The global epigenetic state of MM cells is unknown, partly due to technical difficulty in isolating sufficient numbers of homogenous cell populations. We therefore took advantage of two mouse clonal cell lines representing the uninduced (mK3) and induced (mK4) metanephric mesenchyme (based on gene expression profiles and ability to induce branching of ureteric bud). ChIP-Seq revealed that whereas H3K4me3 active region "peaks" are enriched in metabolic genes, H3K27me3 peaks decorate mesenchyme and epithelial cell fate commitment genes. In uninduced mK3 cells, promoters of "stemness" genes (e.g., Six2, Osr1) are enriched with H3K4me3 peaks; these are lost in induced mK4 cells. ChIP-qPCR confirmed this finding and further demonstrated that G9a/H3K9me2 occupy the promoter region of Six2 in induced cells, consistent with the inactive state of transcription. Conversely, genes that mark the induced epithelialized state (e.g., Lhx1, Pax8), transition from a non-permissive to an active chromatin signature in mK3 vs. mK4 cells, respectively. Importantly, stimulation of Wnt signaling in uninduced mK3 cells provokes an active chromatin state (high H3K4me3, low H3K27me3), recruitment of ?-catenin, and loss of pre-bound histone methyltransferase Ezh2 in silent induced genes followed by activation of transcription. We conclude that the chromatin signature of uninduced and induced cells correlates strongly with their gene expression states, suggesting a role of chromatin-based mechanisms in MM cell fate.
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An effective negative pressure cavitation-microwave assisted extraction for determination of phenolic compounds in P. calliantha H. Andr.
Analyst
PUBLISHED: 06-13-2013
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A novel negative pressure and microwave assisted extraction technique (NMAE) was first proposed and applied for extraction of phenolic compounds from pyrola. [C?MIM]BF? aqueous solution was selected as extraction solvent. Optimal extraction conditions were microwave power 700 W, negative pressure -0.07 MPa, temperature 40 °C, liquid-solid ratio 20 : 1, ionic liquid (IL) concentration 0.5 M, extraction time 15 min. The predominance of NMAE was investigated by comparing with microwave-assisted extraction (MAE) and negative pressure cavitation extraction (NPCE) using a first-order kinetics equation. The C? values of the target compounds by NMAE were from 0.406 to 5.977 mg g?¹ higher than these by MAE and NPCE, which indicated that NMAE had higher extraction yields. The K values of NMAE were also the highest; it was testified that the target compounds could be transferred from matrix into solvent much more effectively by NMAE than by MAE and NPCE. In addition, the NMAE method was validated in terms of repeatability and reproducibility, the relative standard deviation for relative recovery was lower than 5.43 and 8.78%, respectively. Therefore, NMAE was a developed extraction technique for analytical sample preparation. The RP-HPLC-UV method was also successfully applied for the quantification of six target compounds in pyrola.
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[Mass spectrum characterization of five valepotriates by electrospray ionization tandem mass spectrometry].
Zhongguo Zhong Yao Za Zhi
PUBLISHED: 05-30-2013
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To discuss mass spectrum characterization of five valepotriates including monoene type (didrovaltrate), diene type (valtrate, acevaltrate) and four-olefinic type (baldrinal and homobaldrinal) by electrospray ionization tandem mass spectrometry (ESI-MS(n)).
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PPAR?-inactive ?2-troglitazone independently triggers ER stress and apoptosis in breast cancer cells.
Mol. Carcinog.
PUBLISHED: 05-23-2013
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Our aim was to better understand peroxisome proliferator-activated receptor gamma (PPAR?)-independent pathways involved in anti-cancer effects of thiazolidinediones (TZDs). We focused on ?2-troglitazone (?2-TGZ), a PPAR? inactive TZD that affects breast cancer cell viability. Appearance of TUNEL positive cells, changes in mitochondrial membrane potential, cleavage of poly(ADP-ribose) polymerase (PARP)-1 and caspase-7 revealed that apoptosis occurred in both hormone-dependent MCF7 and hormone-independent MDA-MB-231 breast cancer cells after 24 and 48?h of treatment. A microarray study identified endoplasmic reticulum (ER) stress as an essential cellular function since many genes involved in ER stress were upregulated in MCF7 cells following ?2-TGZ treatment. ?2-TGZ-induced ER stress was further confirmed in MCF7 cells by phosphorylation of pancreatic endoplasmic reticulum kinase-like endoplasmic reticulum kinase (PERK) and its target eIF2? after 1.5?h, rapid increase in activating transcription factor (ATF) 3 mRNA levels, splicing of X-box binding protein 1 (XBP1) after 3?h, accumulation of binding immunogloblulin protein (BiP) and CCAAT-enhancer-binding protein homologous protein (CHOP) after 6?h. Immunofluorescence microscopy indicated that CHOP was relocalized to the nucleus of treated cells. Similarly, in MDA-MB-231 cells, overexpression of ATF3, splicing of XBP1, and accumulation of BiP and CHOP were observed following ?2-TGZ treatment. In MCF7 cells, knock-down of CHOP or the inhibition of c-Jun N-terminal kinase (JNK) did not impair cleavage of PARP-1 and caspase-7. Altogether, our results show that ER stress is an early response of major types of breast cancer cells to ?2-TGZ, prior to, but not causative of apoptosis. © 2013 Wiley Periodicals, Inc.
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A three-dimensional polycatenation framework: catena-poly[[diaquabis(4-{4-[4-(pyridin-4-yl)phenoxy]phenyl}pyridine)nickel(II)]-?2-naphthalene-2,6-dicarboxylato].
Acta Crystallogr C
PUBLISHED: 05-14-2013
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In the title compound, [Ni(C12H6O4)(C22H16N2O)2(H2O)2]n, the Ni(2+) cation resides on a centre of inversion in a slightly distorted octahedral [N2O4] environment. The two carboxylate groups of each naphthalene-2,6-dicarboxylate (NDC(2-)) ligand, which reside on centres of inversion, link the Ni(II) cations into a one-dimensional chain. Identical chains are linked by intermolecular hydrogen bonds between coordinated water molecules and the uncoordinated N atoms of 4-{4-[4-(pyridin-4-yl)phenoxy]phenyl}pyridine ligands to form (4,4)-topological sheets, and then the different sheets are interlocked in an inclined fashion to give a three-dimensional polycatenation network. The stability of the structure is further enhanced by ?-? stacking interactions between pyridine and benzene rings.
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Abnormal expression of chondroitin sulphate N-acetylgalactosaminyltransferase 1 and Hapln-1 in cartilage with Kashin-Beck disease and primary osteoarthritis.
Int Orthop
PUBLISHED: 04-16-2013
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Kashin-Beck disease (KBD) is an endemic degenerative osteoarthritis associated with extracellular matrix degradation. The aim of this investigation was to evaluate the role of targeting genes in the pathogenesis of KBD and primary osteoarthritis (OA) involved in extracellular matrix degradation.
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Isolation, characterization and acetylcholinesterase inhibitory activity of alkaloids from roots of Stemona sessilifolia.
Fitoterapia
PUBLISHED: 03-25-2013
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Two new alkaloids, named stenine A (1) and stenine B (2), along with the known compounds neostenine (3), stenine (4) and neotuberostemonine (5), were isolated from the roots of Stemona sessilifolia. Their structures were elucidated by 1D- and 2D-NMR spectra and X-ray single-crystal diffraction experiment. Anti-acetylcholinesterase (AChE) activity of compounds 1-5 were also tested. Compounds 2 and 4 showed significant anti-acetylcholinesterase activities, with IC50 values of 2.1±0.2 ?M and 19.8±2.5 ?M, resp. The mode of AChE inhibition by Compound 2 (the most potential AChE inhibitor) was reversible and competitive. In addition, molecular modeling was performed to explore the binding mode of compound 2 with AChE.
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[Association of MK2 gene polymorphisms with low-density lipoprotein cholesterol and tumor necrosis factor-alpha in Uygur population from Hetian area of Xinjiang].
Zhongguo Yi Xue Ke Xue Yuan Xue Bao
PUBLISHED: 03-09-2013
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To investigate the association of MK2 gene with low density lipoprotein cholesterol (LDL-C) and tumor necrosis factor-alpha (TNF-?) between different gender in Xinjiang Uygur population.
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A facile and efficient strategy to enhance hydrophilicity of zwitterionic sulfoalkylbetaine type monoliths.
J Chromatogr A
PUBLISHED: 02-28-2013
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In order to prepare zwitterionic HILIC monolithic columns with high polarity, the highly hydrophilic monomer N,N-dimethyl-N-acryloyloxyethyl-N-(3-sulfopropyl)ammonium betaine (SPDA) and crosslinker N,N-methylenebisacrylamide (MBA) were employed for developing a novel sulfoalkylbetaine type stationary phase. The polymerization parameters were systematically optimized in order to obtain a satisfactory performance for column permeability, mechanical stability, hydrophilicity, efficiency and selectivity. Compared to the previously reported poly(N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl)ammonium betaine-co-ethylene dimethacrylate) (poly(SPE-co-EDMA)) monolith and the poly(SPDA-co-EDMA) monolith that we developed, a significantly enhanced hydrophilicity was obtained on the poly(SPDA-co-MBA) monolithic column, illustrated by the lowered critical composition of the mobile phase corresponding to the transition from the HILIC to the RP mode. Excellent permeability, reproducibility and stability were achieved on this optimized poly(SPDA-co-MBA) monolith. A column efficiency of 70,000plates/m was obtained for the analysis of bases at a linear velocity of 1.95mm/s. As expected, by studying the influence of mobile phase pH and salt concentration on their retention, a weak electrostatic repulsion interaction for negatively charged analytes was also observed at low organic solvent content on the poly(SPDA-co-MBA) monolithic column. The final optimized poly(SPDA-co-MBA) monolith exhibited good selectivity for a series of polar compounds, such as phenols, bases, benzoic acid derivatives, small peptides, urea and allantoin.
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Variation of active constituents and antioxidant activity in pyrola [P. incarnata Fisch.] from different sites in Northeast China.
Food Chem
PUBLISHED: 02-20-2013
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The variation of antioxidant activity and active components in pyrola [Passiflora incarnata Fisch.] from eight sites in Northeast China were investigated. Total phenolic and flavonoid contents were determined and varied within the range of 39.66-181.48 mg/g and 2.47-22.11 mg/g, respectively. Antioxidant activities were determined by scavenging activity against DPPH and ABTS, by a reducing power test and by a ?-carotene-linoleic acid bleaching test. The IC50 of Tahe samples determined by the DPPH test was 0.106±0.006 mg/mL which was very close to that of Vc (0.076±0.004 mg/mL). The Tahe samples had good antioxidant activity. Principal component activity analysis indicated that the Tahe samples of P. incarnata had the highest potential antioxidant properties, and may be a valuable antioxidant natural resource in the northeast of China.
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Transport and Retention of Selected Engineered Nanoparticles by Porous Media in the Presence of a Biofilm.
Environ. Sci. Technol.
PUBLISHED: 02-13-2013
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Column experiments were conducted to investigate the transport of aqueous C(60) (aqu-nC(60)), fullerol, silver nanoparticles (NPs) coated with polyvinylpyrrolidone (Ag-PVP) and stabilized by citrate (Ag-CIT) in biofilm-laden porous media. Gram-negative Pseudomonas aeruginosa (PA) and Gram-positive Bacillus cereus (BC) biofilm-laden glass beads were selected to represent the bacterial interfaces NPs might encounter in the natural aquatic environment. The biomass distribution, extracellular polymeric substances (EPS) components, electrokinetic property, and hydrophobicity of these interfaces were characterized, and the hydrophobicity was found to correlate with the quantity of proteins in EPS. The retention of NPs on glass beads coated with bovine serum albumin (BSA) and alginate were also studied. Except for Ag-PVP, the affinity of NPs for porous medium, indicated by attachment efficiency ?, increased in the presence of biofilms, BSA and alginate. For hydrophobic aqu-nC(60), the larger the proteins/polysaccharides ratio, the larger the ?, suggesting the hydrophobic interaction determines the attachment of aqu-nC(60) to the collector surface. Uncharged PVP stabilized Ag-PVP by steric repulsion, and the attachment to glass beads was not enhanced by biofilm. The presence of divalent ion Ca(2+) significantly hydrophobized biofilm, BSA, and alginate-coated glass beads and further retarded the mobility of aqu-nC(60), fullerol, and Ag-CIT; while Ag-PVP was again sterically stabilized.
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Comparative transcriptome analysis to investigate the high starch accumulation of duckweed (Landoltia punctata) under nutrient starvation.
Biotechnol Biofuels
PUBLISHED: 02-01-2013
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Duckweed can thrive on anthropogenic wastewater and produce tremendous biomass production. Due to its relatively high starch and low lignin percentage, duckweed is a good candidate for bioethanol fermentation. Previous studies have observed that water devoid of nutrients is good for starch accumulation, but its molecular mechanism remains unrevealed.
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Genetic variations in the KCNJ5 gene in primary aldosteronism patients from Xinjiang, China.
PLoS ONE
PUBLISHED: 01-31-2013
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Primary aldosteronism (PA) is the most common endocrine form of secondary hypertension, and one of the most common subtypes of sporadic PA is aldosterone-producing adenoma (APA). Recently, two somatic mutations of the KCNJ5 gene were implicated in APA, and two germline mutations were associated with familial hyperaldosteronism III.
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Prevalence and risk factors of hepatitis C and B virus infections in hemodialysis patients and their spouses: a multicenter study in Beijing, China.
J. Med. Virol.
PUBLISHED: 01-24-2013
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Hemodialysis patients are at risk for hepatitis C and B virus infections. This study investigated the prevalences and risk factors of HCV and HBV infection and the distribution of HCV genotypes among hemodialysis patients and their spouses. From August to November 2011, a cross-sectional study was conducted on 20 hemodialysis units in Beijing to investigate prevalences and risk factors for markers of HCV and HBV among 2,120 patients and 409 spouses. In hemodialysis patients, prevalences of anti-HCV, HCV RNA, and hepatitis B surface antigen (HBsAg) were 6.1%, 4.6%, and 7.0%, respectively. The prevalence of HCV antibodies among spouses was 0.5%, of HCV RNA was 0.2%, and of HBsAg was 4.2%. Risk factors for HCV infection were dialysis duration, blood transfusion, and attending more than one dialysis unit. HBV infection was independently associated with age, family member with hepatitis infection, gender, and surgery. The predominant HCV genotypes were 1b (89.0%) and 2a (7.7%), and genotypes 3a, 3b, and 6a were each 1.1%. A significant decrease in HCV and HBV prevalences in Chinese dialysis units showed that infection control measures were effective. However, because nosocomial transmissions persist, strict adherence to infection control measures should be emphasized to reduce the risk of transmission.
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Mediator MED23 regulates basal transcription in vivo via an interaction with P-TEFb.
Transcription
PUBLISHED: 01-24-2013
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The Mediator is a multi-subunit complex that transduces regulatory information from transcription regulators to the RNA polymerase II apparatus. Growing evidence suggests that Mediator plays roles in multiple stages of eukaryotic transcription, including elongation. However, the detailed mechanism by which Mediator regulates elongation remains elusive. In this study, we demonstrate that Mediator MED23 subunit controls a basal level of transcription by recruiting elongation factor P-TEFb, via an interaction with its CDK9 subunit. The mRNA level of Egr1, a MED23-controlled model gene, is reduced 4-5 fold in Med23 (-/-) ES cells under an unstimulated condition, but Med23-deficiency does not alter the occupancies of RNAP II, GTFs, Mediator complex, or activator ELK1 at the Egr1 promoter. Instead, Med23 depletion results in a significant decrease in P-TEFb and RNAP II (Ser2P) binding at the coding region, but no changes for several other elongation regulators, such as DSIF and NELF. ChIP-seq revealed that Med23-deficiency partially reduced the P-TEFb occupancy at a set of MED23-regulated gene promoters. Further, we demonstrate that MED23 interacts with CDK9 in vivo and in vitro. Collectively, these results provide the mechanistic insight into how Mediator promotes RNAP II into transcription elongation.
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Eleven new highly oxygenated triterpenoids from the leaves and stems of Schisandra chinensis.
Org. Biomol. Chem.
PUBLISHED: 01-16-2013
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Eleven new triterpenoids, schinchinenins A–H (1–8) and schinchinenlactones A–C (9–11) together with three known triterpenoids, henrischinins A–C (12–14), were isolated from the leaves and stems of Schisandra chinensis by bioassay-guided fractionation. Schinchinenin A (1) is the first example of a highly oxygenated triterpenoid characterized by a 5/5/7/6/5-fused pentacyclic ring and a 3-one-2-oxabicyclo[3.2.1]-octane moiety. Schinchinenins E and F (5 and 6) are highly oxygenated triterpenoids that contain a hydroperoxyl moiety, which is rare in compounds from the Schisandra genus. The structures and stereochemistry of 1–11 were elucidated using spectroscopic analysis, single-crystal X-ray diffraction, computational optical rotation, chemical transformation, and CD exciton chirality methods. The activities of compounds 1, 2, 7, and 12–14 against HSV-2 and adenovirus were evaluated for the first time, and of these compounds, 13 was the most active inhibitor of HSV-2, with a selectivity index value as high as 29.95.
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A clustering protocol for wireless sensor networks based on energy potential field.
ScientificWorldJournal
PUBLISHED: 01-01-2013
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It is the core issue of researching that how to prolong the lifetime of wireless sensor network. The purpose of this paper is to illustrate a clustering protocol LEACH-PF, which is a multihop routing algorithm with energy potential field of divided clusters. In LEACH-PF, the network is divided into a number of subnetworks and each subnetwork has a cluster head. These clusters construct an intercluster routing tree according to the potential difference of different equipotential fields. The other member nodes of the subnetworks communicate with their cluster head directly, so as to complete regional coverage. The results of simulation show that LEACH-PF can reduce energy consumption of the network effectively and prolong the network lifetime.
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[Clinical analysis of level II occult metastasis of papillary thyroid carcinoma].
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 12-20-2011
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To analyze the relevant factors occult II lymph node metastases in papillary thyroid carcinoma (PTC) with clinical factors.
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Three self-penetrated, interlocked, and polycatenated supramolecular isomers via one-pot synthesis and crystallization.
Chem. Commun. (Camb.)
PUBLISHED: 12-02-2011
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Three supramolecular isomers, {[Cd(2)(TPOM)(hfipbb)(2)]·x/y/zsolvent}(n) (1-3), have been synthesized and characterized by one-pot reaction. Even though the compositions of 1-3 are the same, they generate different structures. Reactions over various time periods were found to influence the formation of supramolecular isomers, and there is little influence on this system under other conditions.
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[Relationship between rs3865418 polymorphism of neural precursor cell expressed developmentally downregulated 4-like gene and obesity in Kazakh general population].
Zhongguo Yi Xue Ke Xue Yuan Xue Bao
PUBLISHED: 11-25-2011
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To investigate the relationships between rs3865418 polymorphism of neural precursor cell expressed developmentally downregulated 4-like gene and obesity in Kazakh general population.
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