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Find video protocols related to scientific articles indexed in Pubmed.
Melatonin pretreatment improves the survival and function of transplanted mesenchymal stem cells after focal cerebral ischemia.
Cell Transplant
PUBLISHED: 10-21-2014
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Mesenchymal stem cell (MSC) transplantation has been shown to be beneficial in treating cerebral ischemia. However, such benefit is limited by the low survival of transplanted MSCs in an ischemic microenvironment. Previous studies showed that melatonin pretreatment can increase MSC survival in the ischemic kidney. However, whether it will improve MSC survival in cerebral ischemia is unknown. Our study examined the effect of melatonin pretreatment on MSCs under ischemia-related conditions in vitro and after transplantation into ischemic rat brain. Results showed that melatonin pretreatment greatly increased survival of MSCs in vitro and reduced their apoptosis after transplantation into ischemic brain. Melatonin-treated MSCs (MT-MSCs) further reduced brain infarction and improved neurobehavioral outcomes. Angiogenesis, neurogenesis, and the expression of vascular endothelial growth factor (VEGF) were greatly increased in the MT-MSC-treated rats. Melatonin treatment increased the level of p-ERK1/2 in MSCs, which can be blocked by the melatonin receptor antagonist luzindole. ERK phosphorylation inhibitor U0126 completely reversed the protective effects of melatonin, suggesting that melatonin improves MSC survival and function through activating the ERK1/2 signaling pathway. Thus, stem cells pretreated by melatonin may represent a feasible approach for improving the beneficial effects of stem cell therapy for cerebral ischemia.
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Materials processing routes to trap-free halide perovskites.
Nano Lett.
PUBLISHED: 10-13-2014
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Photovoltaic devices based on lead iodide perovskite films have seen rapid advancements, recently achieving an impressive 17.9% certified solar power conversion efficiency. Reports have consistently emphasized that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films grown under iodine-rich conditions are prone to a high density of deep electronic traps (recombination centers), while the use of a chloride precursor avoids the formation of key defects (Pb atom substituted by I) responsible for short diffusion lengths and poor photovoltaic performance. Furthermore, the lowest-energy surfaces of perovskite crystals are found to be entirely trap-free, preserving both electron and hole delocalization to a remarkable degree, helping to account for explaining the success of polycrystalline perovskite films. We construct perovskite films from I-poor conditions using a lead acetate precursor, and our measurement of a long (600 ± 40 nm) diffusion length confirms this new picture of the importance of growth conditions.
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Perovskite Thin Films via Atomic Layer Deposition.
Adv. Mater. Weinheim
PUBLISHED: 08-28-2014
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A new method to deposit perovskite thin films which benefit from the thickness control and conformality of atomic layer deposition (ALD) is detailed. A seed layer of ALD PbS is place-exchanged with PbI2 and subsequently CH3 NH3 PbI3 perovskite. These films show promising optical properties, with gain coefficients of 3200 ± 830 cm(-1) .
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Genome-wide Hi-C analyses in wild-type and mutants reveal high-resolution chromatin interactions in Arabidopsis.
Mol. Cell
PUBLISHED: 08-14-2014
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Chromosomes form 3D structures that are critical to the regulation of cellular and genetic processes. Here, we present a study of global chromatin interaction patterns in Arabidopsis thaliana. Our genome-wide approach confirmed interactions that were previously observed by other methods as well as uncovered long-range interactions such as those among small heterochromatic regions embedded in euchromatic arms. We also found that interactions are correlated with various epigenetic marks that are localized in active or silenced chromatin. Arabidopsis chromosomes do not contain large local interactive domains that resemble the topological domains described in animals but, instead, contain relatively small interactive regions scattered around the genome that contain H3K27me3 or H3K9me2. We generated interaction maps in mutants that are defective in specific epigenetic pathways and found altered interaction patterns that correlate with changes in the epigenome. These analyses provide further insights into molecular mechanisms of epigenetic regulation of the genome.
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Roles of small RNAs in soybean defense against Phytophthora sojae infection.
Plant J.
PUBLISHED: 06-11-2014
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The genus Phytophthora consists of many notorious pathogens of crops and forestry trees. At present, battling Phytophthora diseases is challenging due to a lack of understanding of their pathogenesis. We investigated the role of small RNAs in regulating soybean defense in response to infection by Phytophthora sojae, the second most destructive pathogen of soybean. Small RNAs, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are universal regulators that repress target gene expression in eukaryotes. We identified known and novel small RNAs that differentially accumulated during P. sojae infection in soybean roots. Among them, miR393 and miR166 were induced by heat-inactivated P. sojae hyphae, indicating that they may be involved in soybean basal defense. Indeed, knocking down the level of mature miR393 led to enhanced susceptibility of soybean to P. sojae; furthermore, the expression of isoflavonoid biosynthetic genes was drastically reduced in miR393 knockdown roots. These data suggest that miR393 promotes soybean defense against P. sojae. In addition to miRNAs, P. sojae infection also resulted in increased accumulation of phased siRNAs (phasiRNAs) that are predominantly generated from canonical resistance genes encoding nucleotide binding-leucine rich repeat proteins and genes encoding pentatricopeptide repeat-containing proteins. This work identifies specific miRNAs and phasiRNAs that regulate defense-associated genes in soybean during Phytophthora infection.
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mTOR signaling inhibition modulates macrophage/microglia-mediated neuroinflammation and secondary injury via regulatory T cells after focal ischemia.
J. Immunol.
PUBLISHED: 05-14-2014
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Signaling by the mammalian target of rapamycin (mTOR) plays an important role in the modulation of both innate and adaptive immune responses. However, the role and underlying mechanism of mTOR signaling in poststroke neuroinflammation are largely unexplored. In this study, we injected rapamycin, a mTOR inhibitor, by the intracerebroventricular route 6 h after focal ischemic stroke in rats. We found that rapamycin significantly reduced lesion volume and improved behavioral deficits. Notably, infiltration of ?? T cells and granulocytes, which are detrimental to the ischemic brain, was profoundly reduced after rapamycin treatment, as was the production of proinflammatory cytokines and chemokines by macrophages and microglia. Rapamycin treatment prevented brain macrophage polarization toward the M1 type. In addition, we also found that rapamycin significantly enhanced anti-inflammation activity of regulatory T cells (Tregs), which decreased production of proinflammatory cytokines and chemokines by macrophages and microglia. Depletion of Tregs partially elevated macrophage/microglia-induced neuroinflammation after stroke. Our data suggest that rapamycin can attenuate secondary injury and motor deficits after focal ischemia by enhancing the anti-inflammation activity of Tregs to restrain poststroke neuroinflammation.
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Air-stable n-type colloidal quantum dot solids.
Nat Mater
PUBLISHED: 05-02-2014
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Colloidal quantum dots (CQDs) offer promise in flexible electronics, light sensing and energy conversion. These applications rely on rectifying junctions that require the creation of high-quality CQD solids that are controllably n-type (electron-rich) or p-type (hole-rich). Unfortunately, n-type semiconductors made using soft matter are notoriously prone to oxidation within minutes of air exposure. Here we report high-performance, air-stable n-type CQD solids. Using density functional theory we identify inorganic passivants that bind strongly to the CQD surface and repel oxidative attack. A materials processing strategy that wards off strong protic attack by polar solvents enabled the synthesis of an air-stable n-type PbS CQD solid. This material was used to build an air-processed inverted quantum junction device, which shows the highest current density from any CQD solar cell and a solar power conversion efficiency as high as 8%. We also feature the n-type CQD solid in the rapid, sensitive, and specific detection of atmospheric NO2. This work paves the way for new families of electronic devices that leverage air-stable quantum-tuned materials.
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Association between leukocyte mitochondrial DNA content and risk of coronary heart disease: A case-control study.
Atherosclerosis
PUBLISHED: 04-25-2014
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Compelling epidemiological evidence indicates that alterations of mitochondrial DNA (mtDNA), including mutations and abnormal content of mtDNA, are associated with the initiation and development of cardiovascular disease. This study was undertaken to investigate whether mtDNA content in peripheral blood leukocytes (PBLs) could be used as a risk predictor for coronary heart disease (CHD).
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Characterization of the microbial community in the rhizosphere of Phragmites australis (cav.) trin ex. steudel growing in the Sun Island Wetland.
Water Environ. Res.
PUBLISHED: 04-17-2014
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Rhizospheric microorganisms are important for environmental conservancy. The constancy and variability of the microorganisms in the rhizosphere of Phragmites australis in relation to the spatiotemporal variations in wetland ecosystems were studied. During the peak and trough of the vegetative period of the Phragmites australis growing across the hydrologic gradients of the Sun Island Wetland, Biolog and denaturing gradient gel electrophoresis (DGGE) were used to investigate the rhizospheric microbial characteristics. Both methods demonstrated that the microbial activity, richness, and diversity decreased from summer to autumn. However, these properties did not show significant correlation with hydrologic gradient, except that the genetic richness and diversity of the fungi decreased with it. Cluster analysis also demonstrated that the rhizospheric microbial community seemed to be largely affected by a vegetative period. In addition, this research was extended to a broader range of determining the universal microorganisms, which showed notable adaptability.
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Reprint of: construction of Specific Parallel Amplification of RNA Ends (SPARE) libraries for the systematic identification of plant microRNA processing intermediates.
Methods
PUBLISHED: 04-13-2014
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MicroRNAs (miRNAs) are small RNAs that derive from endogenous precursors harboring foldback structures. Plant miRNA precursors are quite variable in their size and shape. Still, the miRNA processing machinery, consisting of DICER-LIKE1 (DCL1) and accessory proteins recognize structural features on the precursors to cleave them at specific places releasing the mature miRNAs. The identification of miRNA processing intermediates in plants has mostly relied on a modified 5' RACE method, designed to detect the 5' end of uncapped RNAs. However, this method is time consuming and is, therefore, only practical for the analysis of a handful miRNAs. Here, we present a modification of this approach in order to perform genome-wide analysis of miRNA processing intermediates. Briefly, a reverse transcription is performed with a mixture of specific primers designed against all known miRNA precursors. miRNA processing intermediates are then specifically amplified to generate a library and subjected to deep sequencing. This method, called SPARE (Specific Parallel Amplification of 5' RNA Ends) allows the identification of processing intermediates for most of the Arabidopsis miRNAs. The results enable the determination of the DCL1 processing direction and the cleavage sites introduced by miRNA processing machinery in the precursors. The SPARE method can be easily adapted to detect miRNA-processing intermediates in other systems.
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Determining causal exposure-response relationships with randomized concentration-controlled trials.
J Biopharm Stat
PUBLISHED: 04-05-2014
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Determining causal effects in exposure-response relationships is an important but also a challenging task since confounding factors that affect both drug exposure and response often exist and lead to confounding biases in causal effect estimation. Randomized concentration control (RCC) trials are designed to eliminate or to reduce the confounding bias. However, statistical issues in the design and analysis of these trials have not been examined closely in the literature. Analysis of dose-exposure relationship may also be affected by confounding factors if they affect dose adjustments. We examined these issues and suggest methodological and practical solutions. In particular, we proposed using instrumental variables (IV) for the estimation of causal effects in both exposure-response and dose-exposure relationships. We also examined the impacts of confounded treatment heterogeneity on the IV estimate for RCC trials. We illustrated these approaches with a trial design scenario showing the importance of considering multiple practical factors that may alter the performance of the IV estimate. The performance of the IV estimates was examined by simulations for a wide range of scenarios. The results showed clear advantages for the IV estimates over routine estimates. Some situations in which the IV estimates may fail were also identified.
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Test hysteresis in pharmacokinetic/pharmacodynamic relationship with mixed-effect models: an instrumental model approach.
J Biopharm Stat
PUBLISHED: 03-11-2014
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Hysteresis often occurs between drug exposure and response. To model the hysteresis, one approach is to combine an effect compartment with an instantaneous exposure-response model. The combined model may not be easy to fit when the exposure-response model contains random effects. Therefore, it is sometimes useful to test existence of the hysteresis without fitting the model with an effect compartment. Although the likelihood ratio test and Wald test can be implemented based on a fitted model, they do not solve problems in fitting the combined model such as nonconvergence. Fitting a model without the effect compartment is often much easier, as the model contains fewer parameters with random effects. We propose a novel yet simple test based on an instrumental model that only requires fitting an instantaneous exposure-response model. For a wide range of pharmacokinetic/pharmacodynamic (PK/PD) models, this test can be implemented using commonly used software. The test can be used based on a parametric PK model or based on a nonparametric approach such as linear interpolation. The performance of the proposed test was compared with a test based on lagged covariate models and examined by a simulation study and illustrated by implementing it to an analysis of the relationship between drug concentration and QT interval in a cardiac safety trial.
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Dicer-like 3 produces transposable element-associated 24-nt siRNAs that control agricultural traits in rice.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 02-19-2014
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Transposable elements (TEs) and repetitive sequences make up over 35% of the rice (Oryza sativa) genome. The host regulates the activity of different TEs by different epigenetic mechanisms, including DNA methylation, histone H3K9 methylation, and histone H3K4 demethylation. TEs can also affect the expression of host genes. For example, miniature inverted repeat TEs (MITEs), dispersed high copy-number DNA TEs, can influence the expression of nearby genes. In plants, 24-nt small interfering RNAs (siRNAs) are mainly derived from repeats and TEs. However, the extent to which TEs, particularly MITEs associated with 24-nt siRNAs, affect gene expression remains elusive. Here, we show that the rice Dicer-like 3 homolog OsDCL3a is primarily responsible for 24-nt siRNA processing. Impairing OsDCL3a expression by RNA interference caused phenotypes affecting important agricultural traits; these phenotypes include dwarfism, larger flag leaf angle, and fewer secondary branches. We used small RNA deep sequencing to identify 535,054 24-nt siRNA clusters. Of these clusters, ?82% were OsDCL3a-dependent and showed significant enrichment of MITEs. Reduction of OsDCL3a function reduced the 24-nt siRNAs predominantly from MITEs and elevated expression of nearby genes. OsDCL3a directly targets genes involved in gibberellin and brassinosteroid homeostasis; OsDCL3a deficiency may affect these genes, thus causing the phenotypes of dwarfism and enlarged flag leaf angle. Our work identifies OsDCL3a-dependent 24-nt siRNAs derived from MITEs as broadly functioning regulators for fine-tuning gene expression, which may reflect a conserved epigenetic mechanism in higher plants with genomes rich in dispersed repeats or TEs.
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8-oxoguanine DNA glycosylase-1 augments proinflammatory gene expression by facilitating the recruitment of site-specific transcription factors.
J. Immunol.
PUBLISHED: 01-31-2014
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Among the insidious DNA base lesions, 8-oxo-7,8-dihydroguanine (8-oxoG) is one of the most abundant, a lesion that arises through the attack by reactive oxygen species on guanine, especially when located in cis-regulatory elements. 8-oxoG is repaired by the 8-oxoguanine glycosylase 1 (OGG1)-initiated DNA base excision repair pathway. In this study, we investigated whether 8-oxoG repair by OGG1 in promoter regions is compatible with a prompt gene expression and a host innate immune response. For this purpose, we used a mouse model of airway inflammation, supplemented with cell cultures, chromatin immunoprecipitation, small interfering RNA knockdown, real-time PCR, and comet and reporter transcription assays. Our data show that exposure of cells to TNF-? altered cellular redox, increased the 8-oxoG level in DNA, recruited OGG1 to promoter sequences, and transiently inhibited base excision repair of 8-oxoG. Promoter-associated OGG1 then enhanced NF-?B/RelA binding to cis-elements and facilitated recruitment of specificity protein 1, transcription initiation factor II-D, and p-RNA polymerase II, resulting in the rapid expression of chemokines/cytokines and inflammatory cell accumulation in mouse airways. Small interfering RNA depletion of OGG1 or prevention of guanine oxidation significantly decreased TNF-?-induced inflammatory responses. Taken together, these results show that nonproductive binding of OGG1 to 8-oxoG in promoter sequences could be an epigenetic mechanism to modulate gene expression for a prompt innate immune response.
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miRNAs trigger widespread epigenetically activated siRNAs from transposons in Arabidopsis.
Nature
PUBLISHED: 01-22-2014
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In plants, post-transcriptional gene silencing (PTGS) is mediated by DICER-LIKE 1 (DCL1)-dependent microRNAs (miRNAs), which also trigger 21-nucleotide secondary short interfering RNAs (siRNAs) via RNA-DEPENDENT RNA POLYMERASE 6 (RDR6), DCL4 and ARGONAUTE 1 (AGO1), whereas transcriptional gene silencing (TGS) of transposons is mediated by 24-nucleotide heterochromatic (het)siRNAs, RDR2, DCL3 and AGO4 (ref. 4). Transposons can also give rise to abundant 21-nucleotide 'epigenetically activated' small interfering RNAs (easiRNAs) in DECREASED DNA METHYLATION 1 (ddm1) and DNA METHYLTRANSFERASE 1 (met1) mutants, as well as in the vegetative nucleus of pollen grains and in dedifferentiated plant cell cultures. Here we show that easiRNAs in Arabidopsis thaliana resemble secondary siRNAs, in that thousands of transposon transcripts are specifically targeted by more than 50 miRNAs for cleavage and processing by RDR6. Loss of RDR6, DCL4 or DCL1 in a ddm1 background results in loss of 21-nucleotide easiRNAs and severe infertility, but 24-nucleotide hetsiRNAs are partially restored, supporting an antagonistic relationship between PTGS and TGS. Thus miRNA-directed easiRNA biogenesis is a latent mechanism that specifically targets transposon transcripts, but only when they are epigenetically reactivated during reprogramming of the germ line. This ancient recognition mechanism may have been retained both by transposons to evade long-term heterochromatic silencing and by their hosts for genome defence.
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Effect of HMGB1 on the paracrine action of EPC promotes post-ischemic neovascularization in mice.
Stem Cells
PUBLISHED: 01-10-2014
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Transplantation of endothelial progenitor cells (EPCs) leads to better outcomes in experimental stroke, but the mechanism remains unclear. It was reported that astrocytic-high mobility group box1 (HMGB1) promoted endogenous EPC-mediated neurovascular remodeling during stroke recovery. It is unclear whether HMGB1 involves in exogenous EPC-mediated stroke recovery. In this study, we aim to explore whether microglial HMGB1 contributes to human peripheral blood-derived (hPB)-EPCs-mediated neurovascular remodeling by modulating the paracrine function of exogenous hPB-EPCs. Coculturing hPB-EPCs with lipopolysaccharides stimulated BV2 cells upregulated Interleukin-8 expression in hPB-EPCs; this was blocked by treating BV2 cells with HMGB1 inhibitor Glycyrrhizin. Conditioned medium (CM) of hPB-EPCs cocultured with BV2 cells promoted the viability and tube formation of human umbilical cord vein cells. Inhibiting either HMGB1 or IL-8 could block the effect of hPB-EPCs CM. In vivo study showed hPB-EPCs transplantation improved neurobehavioral outcomes, reduced brain atrophy volume, and enhanced neovascularization in transient middle cerebral artery occlusion (tMCAO) mice. Intraperitoneally administration of HMGB1 inhibitor glycyrrhizin blocked the beneficial effect of hPB-EPC transplantation. We did not observe the integration of green fluorescent protein-labeled hPB-EPCs with microvessels in peri-infarct areas at day-14 after tMCAO. In summary, the result suggested that HMGB1 upregulation in postischemic brain could promote exogenous hPB-EPC-mediated stroke recovery by modulating paracrine function of hPB-EPCs.
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Rapamycin attenuates mitochondrial dysfunction via activation of mitophagy in experimental ischemic stroke.
Biochem. Biophys. Res. Commun.
PUBLISHED: 01-10-2014
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Rapamycin has been demonstrated to exhibit neuroprotective functions via the activation of autophagy in a cerebral ischemia model. However, the involvement of mitophagy in this process and its contribution to the protection of mitochondrial function remains unknown. The present study explored the characteristics of mitophagy after cerebral ischemia and the effect of rapamycin on mitochondrial function. Male Sprague-Dawley rats underwent transient middle cerebral artery occlusion (tMCAO). Neurological deficits scores; infarct volumes; mitophagy morphology; and the levels of malondialdehyde (MDA), adenosine triphosphate (ATP) and mitochondrial membrane potentials (??m) were examined. The expression of LC3, Beclin-1 and p62 in the mitochondrial fraction combined with transmission electronic microscopy were used to explore mitophagic activity after ischemia. We also blocked autophagosome formation using 3-methyladenine (3-MA) to check the linkage between the mitochondrial protective effect of rapamycin and enhanced mitophagy. We observed that rapamycin significantly enhanced mitophagy, as evidenced by the increase in LC3-II and Beclin-1 expression in the mitochondria and p62 translocation to the mitochondria. Rapamycin reduced infarct volume, improved neurological outcomes and inhibited mitochondrial dysfunction compared with the control animals (p<0.05). However, these protective effects were reversed by 3-methyladenine treatment after rapamycin. The present study indicates that rapamycin treatment attenuates mitochondrial dysfunction following cerebral ischemia, which is linked to enhanced mitophagy.
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Neural stem cell protects aged rat brain from ischemia-reperfusion injury through neurogenesis and angiogenesis.
J. Cereb. Blood Flow Metab.
PUBLISHED: 01-07-2014
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Neural stem cells (NSCs) show therapeutic potential for ischemia in young-adult animals. However, the effect of aging on NSC therapy is largely unknown. In this work, NSCs were transplanted into aged (24-month-old) and young-adult (3-month-old) rats at 1 day after stroke. Infarct volume and neurobehavioral outcomes were examined. The number of differentiated NSCs was compared in aged and young-adult ischemic rats and angiogenesis and neurogenesis were also determined. We found that aged rats developed larger infarcts than young-adult rats after ischemia (P<0.05). The neurobehavioral outcome was also worse for aged rats comparing with young-adult rats. Brain infarction and neurologic deficits were attenuated after NSC transplantation in both aged and young-adult rats. The number of survived NSCs in aged rats was similar to that of the young-adult rats (P>0.05) and most of them were differentiated into glial fibrillary acidic protein(+) (GFAP(+)) cells. More importantly, angiogenesis and neurogenesis were greatly enhanced in both aged and young-adult rats after transplantation compared with phosphate-buffered saline (PBS) control (P<0.05), accompanied by increased expression of vascular endothelial growth factor (VEGF). Our results showed that NSC therapy reduced ischemic brain injury, along with increased angiogenesis and neurogenesis in aged rats, suggesting that aging-related microenvironment does not preclude a beneficial response to NSCs transplantation during cerebral ischemia.
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8-Oxoguanine DNA glycosylase-1-mediated DNA repair is associated with Rho GTPase activation and ?-smooth muscle actin polymerization.
Free Radic. Biol. Med.
PUBLISHED: 01-04-2014
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Reactive oxygen species (ROS) are activators of cell signaling and modify cellular molecules, including DNA. 8-Oxo-7,8-dihydroguanine (8-oxoG) is one of the prominent lesions in oxidatively damaged DNA, whose accumulation is causally linked to various diseases and aging processes, whereas its etiological relevance is unclear. 8-OxoG is repaired by the 8-oxoguanine DNA glycosylase-1 (OGG1)-initiated DNA base excision repair (BER) pathway. OGG1 binds free 8-oxoG and this complex functions as an activator of Ras family GTPases. Here we examined whether OGG1-initiated BER is associated with the activation of Rho GTPase and mediates changes in the cytoskeleton. To test this possibility, we induced OGG1-initiated BER in cultured cells and mouse lungs and used molecular approaches such as active Rho pull-down assays, siRNA ablation of gene expression, immune blotting, and microscopic imaging. We found that OGG1 physically interacts with Rho GTPase and, in the presence of 8-oxoG base, increases Rho-GTP levels in cultured cells and lungs, which mediates ?-smooth muscle actin (?-SMA) polymerization into stress fibers and increases the level of ?-SMA in insoluble cellular/tissue fractions. These changes were absent in cells lacking OGG1. These unexpected data and those showing that 8-oxoG repair is a lifetime process suggest that, via Rho GTPase, OGG1 could be involved in the cytoskeletal changes and organ remodeling observed in various chronic diseases.
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Methylene blue promotes quiescence of rat neural progenitor cells.
Front Cell Neurosci
PUBLISHED: 01-01-2014
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Neural stem cell-based treatment holds a new therapeutic opportunity for neurodegenerative disorders. Here, we investigated the effect of methylene blue on proliferation and differentiation of rat neural progenitor cells (NPCs) both in vitro and in vivo. We found that methylene blue inhibited proliferation and promoted quiescence of NPCs in vitro without affecting committed neuronal differentiation. Consistently, intracerebroventricular infusion of methylene blue significantly inhibited NPC proliferation at the subventricular zone (SVZ). Methylene blue inhibited mTOR signaling along with down-regulation of cyclins in NPCs in vitro and in vivo. In summary, our study indicates that methylene blue may delay NPC senescence through enhancing NPCs quiescence.
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Neurogenesis in neurological and psychiatric diseases and brain injury: From bench to bedside.
Prog. Neurobiol.
PUBLISHED: 10-06-2013
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Researchers who have uncovered the presence of stem cells in an adults central nervous system have not only challenged the dogma that new neurons cannot be generated during adulthood, but also shed light on the etiology and disease mechanisms underlying many neurological and psychiatric disorders. Brain trauma, neurodegenerative diseases, and psychiatric disorders pose enormous burdens at both personal and societal levels. Although medications for these disorders are widely used, the treatment mechanisms underlying the illnesses remain largely elusive. In the past decade, an increasing amount of evidence indicate that adult neurogenesis (i.e. generating new CNS neurons during adulthood) may be involved in the pathology of different CNS disorders, and thus neurogenesis may be a potential target area for treatments. Although the new neurons were shown to be a major player in mediating treatment efficacy of neurological and psychotropic drugs on cognitive functions, it is still debatable if the altered production of new neurons can cause the disorders. This review hence seeks to discuss pre and current clinical studies that demonstrate the functional impact adult neurogenesis have on neurological and psychiatric illnesses while examining the related underlying disease mechanisms.
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Parallel analysis of RNA ends enhances global investigation of microRNAs and target RNAs of Brachypodium distachyon.
Genome Biol.
PUBLISHED: 09-24-2013
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The wild grass Brachypodium distachyon has emerged as a model system for temperate grasses and biofuel plants. However, the global analysis of miRNAs, molecules known to be key for eukaryotic gene regulation, has been limited in B. distachyon to studies examining a few samples or that rely on computational predictions. Similarly an in-depth global analysis of miRNA-mediated target cleavage using Parallel Analysis of RNA Ends (PARE) data is lacking in B. distachyon.
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Multiple RNA recognition patterns during microRNA biogenesis in plants.
Genome Res.
PUBLISHED: 08-29-2013
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MicroRNAs (miRNAs) derive from longer precursors with fold-back structures. While animal miRNA precursors have homogenous structures, plant precursors comprise a collection of fold-backs with variable size and shape. Here, we design an approach to systematically analyze miRNA processing intermediates and characterize the biogenesis of most of the evolutionarily conserved miRNAs present in Arabidopsis thaliana. We found that plant miRNAs are processed by four mechanisms, depending on the sequential direction of the processing machinery and the number of cuts required to release the miRNA. Classification of the precursors according to their processing mechanism revealed specific structural determinants for each group. We found that the complexity of the miRNA processing pathways occurs in both ancient and evolutionarily young sequences and that members of the same family can be processed in different ways. We observed that different structural determinants compete for the processing machinery and that alternative miRNAs can be generated from a single precursor. The results provide an explanation for the structural diversity of miRNA precursors in plants and new insights toward the understanding of the biogenesis of small RNAs.
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Effect of photocurrent enhancement in porphyrin-graphene covalent hybrids.
Mater Sci Eng C Mater Biol Appl
PUBLISHED: 07-30-2013
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Graphene oxide (GO) sheets were covalently functionalized with 5-p-aminophenyl-10,15,20-triphenylporphyrin (NH2TPP) by an amidation reaction between the amino group in NH2TPP and carboxyl groups in GO. The Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning and transmission electron microscopies reveal that NH2TPP covalent bonds form on the double surface of graphene oxide sheets, generating a unique nano-framework, i.e., NH2TPP-graphene-NH2TPP. Its UV-visible spectroscopy reveals that the absorption spectrum is not a linear superposition of the spectra of NH2TPP and graphene oxide, because a 59nm red shift of the strong graphene oxide absorption is observed from 238 to 297nm, with significant spectral broadening between 300 and 700nm. Fluorescence emission spectroscopy indicates efficient quenching of NH2TPP photoluminescence in this hybrid material, suggesting that photo-induced electron transfer occurs at the interface between NH2TPP and GO. A reversible on/off photo-current density of 47mA/cm(2) is observed when NH2TPP-graphene-NH2TPP hybrid sandwiches are subjected to pulsed white-light illumination. Covalently-bound porphyrins decrease the optical HOMO/LUMO band gap of graphene oxide by ?1eV, according to UV-visible spectroscopy. Cyclic voltammetry predicts a small HOMO/LUMO band gap of 0.84eV for NH2TPP-graphene-NH2TPP hybrid sandwiches, which is consistent with efficient electron transfer and fluorescence quenching.
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Assessment of three techniques for delivering stem cells to the heart using PET and MR imaging.
EJNMMI Res
PUBLISHED: 07-24-2013
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Stem cell therapy has a promising potential for the curing of various degenerative diseases, including congestive heart failure (CHF). In this study, we determined the efficacy of different delivery methods for stem cell administration to the heart for the treatment of CHF. Both positron emission tomography (PET) and magnetic resonance imaging (MRI) were utilized to assess the distribution of delivered stem cells.
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Plant microRNAs display differential 3 truncation and tailing modifications that are ARGONAUTE1 dependent and conserved across species.
Plant Cell
PUBLISHED: 07-09-2013
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Plant small RNAs are 3 methylated by the methyltransferase HUA1 ENHANCER1 (HEN1). In plant hen1 mutants, 3 modifications of small RNAs, including oligo-uridylation (tailing), are associated with accelerated degradation of microRNAs (miRNAs). By sequencing small RNAs of the wild type and hen1 mutants from Arabidopsis thaliana, rice (Oryza sativa), and maize (Zea mays), we found 3 truncation prior to tailing is widespread in these mutants. Moreover, the patterns of miRNA truncation and tailing differ substantially among miRNA families but are conserved across species. The same patterns are also observable in wild-type libraries from a broad range of species, only at lower abundances. ARGONAUTE (AGO1), even with defective slicer activity, can bind these truncated and tailed variants of miRNAs. An ago1 mutation in hen1 suppressed such 3 modifications, indicating that they occur while miRNAs are in association with AGO1, either during or after RNA-induced silencing complex assembly. Our results showed AGO1-bound miRNAs are actively 3 truncated and tailed, possibly reflecting the activity of cofactors acting in conserved patterns in miRNA degradation.
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Construction of Specific Parallel Amplification of RNA Ends (SPARE) libraries for the systematic identification of plant microRNA processing intermediates.
Methods
PUBLISHED: 07-08-2013
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MicroRNAs (miRNAs) are small RNAs that derive from endogenous precursors harboring foldback structures. Plant miRNA precursors are quite variable in their size and shape. Still, the miRNA processing machinery, consisting of DICER-LIKE1 (DCL1) and accessory proteins recognize structural features on the precursors to cleave them at specific places releasing the mature miRNAs. The identification of miRNA processing intermediates in plants has mostly relied on a modified 5 RACE method, designed to detect the 5 end of uncapped RNAs. However, this method is time consuming and is, therefore, only practical for the analysis of a handful miRNAs. Here, we present a modification of this approach in order to perform genome-wide analysis of miRNA processing intermediates. Briefly, a reverse transcription is performed with a mixture of specific primers designed against all known miRNA precursors. miRNA processing intermediates are then specifically amplified to generate a library and subjected to deep sequencing. This method, called SPARE (Specific Parallel Amplification of 5 RNA Ends) allows the identification of processing intermediates for most of the Arabidopsis miRNAs. The results enable the determination of the DCL1 processing direction and the cleavage sites introduced by miRNA processing machinery in the precursors. The SPARE method can be easily adapted to detect miRNA-processing intermediates in other systems.
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A microfluidic origami electrochemiluminescence aptamer-device based on a porous Au-paper electrode and a phenyleneethynylene derivative.
Chem. Commun. (Camb.)
PUBLISHED: 06-28-2013
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A simple, low-cost, and sensitive 3D microfluidic origami electrochemiluminescence aptamer-device was developed based on a novel gold nanoparticle modified porous paper working electrode for point-of-care diagnosis.
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Doping control via molecularly engineered surface ligand coordination.
Adv. Mater. Weinheim
PUBLISHED: 06-18-2013
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A means to control the net doping of a CQD solid is identified via the design of the bidentate ligand crosslinking the material. The strategy does not rely on implementing different atmospheres at different steps in device processing, but instead is a robust strategy implemented in a single processing ambient. We achieve an order of magnitude difference in doping that allows us to build a graded photovoltaic device and maintain high current and voltage at maximum power-point conditions.
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p85-RhoGDI2, a novel complex, is required for PSGL-1-induced ?1 integrin-mediated lymphocyte adhesion to VCAM-1.
Int. J. Biochem. Cell Biol.
PUBLISHED: 06-03-2013
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P-selectin glycoprotein ligand-1 and ?1 integrin play essential roles in T cell trafficking during inflammation. E-selectin and vascular cell adhesion molecule-1 are their ligands expressed on inflammation-activated endothelium. During the tethering and rolling of lymphocytes on endothelium, P-selectin glycoprotein ligand-1 binds E-selectin and induces signals. Subsequently, ?1 integrin is activated and mediates stable adhesion. However, the intracellular signal pathways from PSGL-1 to ?1 integrin have not yet been fully understood. Here, we find that p85, a regulatory subunit of phosphoinositide 3-kinase, forms a novel complex with Rho-GDP dissociation inhibitor-2, a lymphocyte-specific RhoGTPases dissociation inhibitor. Phosporylations of the p85-bound Rho-GDP dissociation inhibitor-2 on 130 and 153 tyrosine residues by c-Abl and Src were required for the complex to be recruited to P-selectin glycoprotein ligand-1 and thereby regulate ?1 integrin-mediated T cell adhesion to vascular cell adhesion molecule-1. Both shRNAs to Rho-GDP dissociation inhibitor-2 and p85 and over-expression of Rho-GDP dissociation inhibitor-2 Y130F and Y153F significantly reduced the above-mentioned adhesion. Although Rho-GDP dissociation inhibitor-2 in the p85-Rho-GDP dissociation inhibitor-2 complex was also phosphorylated on 24 tyrosine residue by Syk, the phosphorylation is not required for the adhesion. Taken together, we find that specific phosphorylations on 130 and 153 tyrosine residues of p85-bound Rho-GDP dissociation inhibitor-2 are pivotal for P-selectin glycoprotein ligand-1-induced ?1 integrin-mediated lymphocyte adhesion to vascular cell adhesion molecule-1. This will shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.
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Comprehensive investigation of microRNAs enhanced by analysis of sequence variants, expression patterns, ARGONAUTE loading, and target cleavage.
Plant Physiol.
PUBLISHED: 05-24-2013
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MicroRNAs (miRNAs) are a class of small RNAs that typically function by guiding the cleavage of target messenger RNAs. They have been shown to play major roles in a variety of plant processes, including development, and responses to pathogens and environmental stresses. To identify new miRNAs and regulation in Arabidopsis (Arabidopsis thaliana), 27 small RNA libraries were constructed and sequenced from various tissues, stresses, and small RNA biogenesis mutants, resulting in 95 million genome-matched sequences. The use of rdr2 to enrich the miRNA population greatly enhanced this analysis and led to the discovery of new miRNAs arising from both known and new precursors, increasing the total number of Arabidopsis miRNAs by about 10%. Parallel Analysis of RNA Ends data provide evidence that the majority guide target cleavage. Many libraries represented novel stress/tissue conditions, such as submergence-stressed flowers, which enabled the identification of new stress regulation of both miRNAs and their targets, all of which were validated in wild-type plants. By combining small RNA expression analysis with ARGONAUTE immunoprecipitation data and global target cleavage data from Parallel Analysis of RNA Ends, a much more complete picture of Arabidopsis miRNAs was obtained. In particular, the discovery of ARGONAUTE loading and target cleavage biases gave important insights into tissue-specific expression patterns, pathogen responses, and the role of sequence variation among closely related miRNA family members that would not be evident without this combinatorial approach.
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mTOR activation in immature cells of primary nasopharyngeal carcinoma and anti-tumor effect of rapamycin in vitro and in vivo.
Cancer Lett.
PUBLISHED: 05-10-2013
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The mammalian target of rapamycin (mTOR) signaling is a key pathway in the progression of different cancers and in the homeostasis of stem cells. Here, we investigated the link between mTOR signaling and cancer stem cells (CSCs) in nasopharyngeal carcinoma (NPC). We found that human primary NPC expressed embryonic stem cell (ESC) markers: CD133, SOX2 and OCT4 as well as pmTOR and pS6. Primary ESC-positive NPC cells could form secondary NPC in BALB/c nude mice. Rapamycin, an mTOR inhibitor, significantly suppressed ESC-positive NPC cell growth in vitro and tumor formation in vivo. Our findings suggest that mTOR signaling is activated in CSC-like cells and plays an important role in NPC growth.
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Rapid construction of parallel analysis of RNA end (PARE) libraries for Illumina sequencing.
Methods
PUBLISHED: 05-08-2013
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MicroRNAs (miRNAs) are ?21nt small RNAs that pair to their target mRNAs and in many cases trigger cleavage, particularly in plants. Although many computational tools can predict miRNA:mRNA interactions, it remains critical to validate cleavage events, due to miRNA function in translational repression or due to high rates of false positives (over 90%) for unvalidated target predictions. A few years ago, three laboratories described similar methods to validate cleavage of miRNA targets by the cloning en masse of 5 ends of cleaved or uncapped mRNAs. To take advantage of the recent progress in high-throughput sequencing technology, we have devised an updated protocol to (1) enable much faster library preparation, and (2) reduce the cost by pooling indexed samples together for sequencing. Here we provide a step-by-step protocol for PARE library construction, starting from total RNA. This protocol has been successfully used in our laboratory to validate miRNA targets in a variety of plant species. We also provide advice for troubleshooting on some common issues.
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Melatonin pretreatment improves the survival and function of transplanted mesenchymal stem cells after focal cerebral ischemia.
Cell Transplant
PUBLISHED: 05-03-2013
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Mesenchymal stem cell (MSC) transplantation has been shown to be beneficial intreating cerebral ischemia. However, such benefit is limited by the low survival oftransplanted MSCs in an ischemic microenvironment. Previous studies showed thatmelatonin pretreatment can increase MSC survival in the ischemic kidney. However, whetherit will improve MSC survival in cerebral ischemia is unknown. Our study examined the effectof melatonin pretreatment on MSCs under ischemia-related conditions in vitro and aftertransplantation into ischemic rat brain. Results showed that melatonin pretreatment greatlyincreased MSC survival in vitro and reduced their apoptosis after transplantation intoischemic brain. Melatonin-treated MSCs (MT-MSCs) further reduced brain infarction andimproved neurobehavioral outcomes. Angiogenesis, neurogenesis and the expression ofvascular endothelial growth factor (VEGF) were greatly increased in the MT-MSC-treatedrats. Melatonin treatment increased the level of p-Erk1/2 in MSCs, which can be blocked bythe melatonin receptor antagonist luzindole. Erk phosphorylation inhibitor U0126 completelyreversed the protective effects of melatonin, suggesting that melatonin improves MSCsurvival and function through activating the Erk1/2 signaling pathway. Thus, stem cellspretreated by melatonin may represent a feasible approach for improving the beneficialeffects of stem cell therapy for cerebral ischemia.
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Physiological stressors and invasive plant infections alter the small RNA transcriptome of the rice blast fungus, Magnaporthe oryzae.
BMC Genomics
PUBLISHED: 05-02-2013
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The rice blast fungus, Magnaporthe oryzae is a destructive pathogen of rice and other related crops, causing significant yield losses worldwide. Endogenous small RNAs (sRNAs), including small interfering RNAs (siRNAs) and microRNAs (miRNAs) are critical components of gene regulation in many eukaryotic organisms. Recently several new species of sRNAs have been identified in fungi. This fact along with the availability of genome sequence makes M. oryzae a compelling target for sRNA profiling. We have examined sRNA species and their biosynthetic genes in M. oryzae, and the degree to which these elements regulate fungal stress responses. To this end, we have characterized sRNAs under different physiological stress conditions, which had not yet been examined in this fungus.
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A rapid in situ immobilization of D-amino acid oxidase based on immobilized metal affinity chromatography.
Bioprocess Biosyst Eng
PUBLISHED: 05-01-2013
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A rapid in situ immobilization process was developed based on conventional separation technique of immobilized metal affinity chromatography (IMAC) and was studied in the case of D-amino acid oxidase (DAAO) with binding-enhancing Heli-tag (His-Arg-Asn-Tyr-Gly-Gly-Cys-Cys-Gly). A recombinant Escherichia coli strain JM105 (?ase)/pGEMK-R-DAAO-Heli was successfully constructed to synthesize chimeric protein DAAO-Heli. Without additional purification procedure, the tagged enzyme DAAO-Heli could be directly immobilized to EP-IDA-Ni(2+) support with purity of 90 % and DAAO activity of over 70 U/g support. Experimental results showed that the immobilized DAAO-Heli was 73 times more thermally stable than free enzyme. Besides, it remained 67 % of initial activity after 100 cycles of batch catalysis and its operational stability was improved 36 times than that of the previously IMAC-immobilized DAAO-His. Furthermore, the epoxy (EP) support could be easily recovered and repeatedly used with simple steps, which could reduce the immobilization costs significantly.
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[A cohort study on risk factors of lung cancer in Yunnan tin miners].
Zhongguo Fei Ai Za Zhi
PUBLISHED: 04-23-2013
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Smoking is a major cause of lung cancer. Studies of lung cancer among miners have shown that occupational exposure also played an important role. The aim of this study is to investigate radon, cigarette use and other risk factors of lung cancer in Yunnan tin miners and to provide a scientific basis for the prevention and control of occupational lung cancer.
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In situ assembly of porous Au-paper electrode and functionalization of magnetic silica nanoparticles with HRP via click chemistry for Microcystin-LR immunoassay.
Biosens Bioelectron
PUBLISHED: 03-22-2013
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A simple, low-cost and sensitive origami electrochemical immunoassay-device was developed based on a novel gold nanoparticle modified porous paper working electrode (Au-PWE) for point-of-care testing. Azide-functionalized Au-PWE was prepared by the functionalization of Au-PWE with 1-azidoundecan-11-thiol. Alkyne end-terminated antibody was prepared with 4-pentynoic acid and antibody by the 1-ethyl-3-(3-(dimethylamino) propyl) carbodiimide hydrochloride and N-hydroxysuccinimide activation reaction. Alkyne-antibody was coupled to azido-Au-PWE by click reaction as a recognition element. Nearly monodispersed sphere-like silica-coated ferroferric oxide (Fe3O4@SiO2) nanoparticles were prepared via the reverse microemulsion method. Azide-functionalized Fe3O4@SiO2 was prepared by the functionalization of silica shell with 3-bromopropyltrichlorosilane followed by substitution with sodium azide. Alkyne-functionalized antibody and horse radish peroxidase were coupled to azide-functionalized Fe3O4@SiO2 by click reaction as signal label. Horse radish peroxidase and ferroferric oxide could catalyze the oxidation of thionine in the presence of hydrogen peroxide. After the sandwich immunoreaction, the current was proportional to the logarithm of the Microcystin-LR. The linear regression equation was i(?A)=119.89+46.27 log cMC-LR (?g/mL) in the range from 0.01 to 200 ?g/mL. The limit of detection was 0.004 ?g/mL. This immunoassay would provide a universal immunoassay method in environmental monitoring and public health.
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Electrochemiluminescence of blue-luminescent graphene quantum dots and its application in ultrasensitive aptasensor for adenosine triphosphate detection.
Biosens Bioelectron
PUBLISHED: 02-23-2013
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A simple approach based on exfoliating and disintegrating treatments for graphite oxide, followed by hydrothermal synthesis, was developed to prepare water-soluble graphene quantum dots (GQDs). The as-prepared GQDs exhibited bright blue emission under ultraviolet irradiation (?365nm), and showed an excitation-independent photoluminescence feature. More importantly, a newly anodic electrochemiluminescence (ECL) was observed from the water-soluble GQDs with H2O2 as coreactant for the first time, and the ECL induced a strong light emission at a low potential (ca. 0.4V vs. Ag/AgCl). The ECL mechanism is investigated in detail. Employing SiO2 nanospheres as signal carrier, a novel SiO2/GQDs ECL signal amplification labels were synthesized based on which a ultrasensitive ECL aptamer sensor was proposed. Under the optimized experimental conditions, the proposed ECL aptamer sensor exhibited excellent analytical performance for adenosine triphosphate (ATP) determination, ranging from 5.0×10(-12) to 5.0×10(-9)molL(-1) with the detection limit of 1.5×10(-12)molL(-1). Due to the low cytotoxicity and excellent biocompatibility, GQDs are demonstrated to be an eco-friendly material as well as excellent ECL labeling agents for biosensor.
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[Clinical research progress of direct surgical repair of lumbar spondylolysis in young patients].
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi
PUBLISHED: 02-23-2013
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To review and summarize the surgical techniques and their outcomes for the treatment of lumbar spondylolysis in young patients by direct surgical repair.
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Effects of vegetative-periodic-induced rhizosphere variation on the uptake and translocation of metals in Phragmites australis (Cav.) Trin ex. Steudel growing in the Sun Island Wetland.
Ecotoxicology
PUBLISHED: 02-09-2013
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To evaluate the vegetative periodic effect of rhizosphere on the patterns of metal bioaccumulation, the concentrations of Mg, K, Ca, Mn, Zn, Fe, Cu, Cr, Ni, Cd and Pb in the corresponding rhizosphere soil and tissues of Phragmites australis growing in the Sun Island wetland (Harbin, China) were compared. The concentrations of Zn, Fe, Cu, Cr, Ni, Cd and Pb in roots were higher than in shoots, suggesting that roots are the primary accumulation organs for these metals and there exists an exclusion strategy for metal tolerance. In contrast, the rest of the metals showed an opposite trend, suggesting that they were not restricted in roots. Harvesting would particularly be an effective method to remove Mn from the environment. The concentrations of metals in shoots were generally higher in autumn than in summer, suggesting that Ph. australis possesses an efficient root-to-shoot translocation system, which is activated at the end of the growing season and allows more metals into the senescent tissues. Furthermore, metal bioaccumulation of Ph. australis was affected by vegetative periodic variation through the changing of physicochemical and microbial conditions. The rhizospheric microbial characteristics were significantly related to the concentrations of Mg, K, Zn, Fe and Cu, suggesting that microbial influence on metal accumulation is specific and selective, not eurytopic.
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Graded doping for enhanced colloidal quantum dot photovoltaics.
Adv. Mater. Weinheim
PUBLISHED: 02-05-2013
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A novel approach to improving all-inorganic colloidal quantum dot (CQD) homojunction solar cells by engineering the doping spatial profile to produce a doping gradient within the n-type absorber is presented. The doping gradient greatly improves carrier collection and enhances the voltages attainable by the device, leading to a 1 power point power conversion efficiency (PCE) improvement over previous inorganic CQD solar cells.
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Biogenesis and function of rice small RNAs from non-coding RNA precursors.
Curr. Opin. Plant Biol.
PUBLISHED: 01-30-2013
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Non-coding RNAs, especially small RNAs, play important roles in many biological processes. Several small RNA types, including microRNAs (miRNAs) and small interfering RNAs (siRNAs), are well-described in rice (Oryza sativa), although much remains to be learned about their function. Many small RNAs along with their targets have been characterized with deep sequencing technologies. Some special classes of these small RNAs have been found to be unique to rice or within the larger group of grasses. The functional and biological roles of numerous plants small RNAs have been described in detail, including functions as varied as the regulation of tissue development, phase transition, or abiotic and biotic stress resistance. Mutant analysis has proven useful in the genetic identification of components involved in small RNA biogenesis and also in identification of regulatory functions of small RNAs. Although many small RNAs have been identified by deep sequencing in rice, their precise regulatory functions and cell-type specificity are in many cases still unknown.
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Silica-coated superparamagnetic iron oxide nanoparticles targeting of EPCs in ischemic brain injury.
Biomaterials
PUBLISHED: 01-17-2013
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Intravenous transplantation of endothelial progenitor cells (EPCs) reduced ischemic brain injury. However, less cell homing to damaged sites limited its functions. In present study, we labeled EPCs with silica-coated superparamagnetic iron oxide nanoparticles (SiO4@SPIONs) and applied exterior magnetic field to guide SiO4@SPIONs-labeled EPCs (SiO4@SPIONs-EPCs) to the ischemic hemisphere of the brain. We optimized SiO4@SPIONs labeling dose, which did not affect proliferation, migration and tube formation of EPCs in vitro. SiO4@SPIONs-EPCs homing was greatly increased in ischemic hemisphere with magnetic field treatment in mice underwent transient middle cerebral artery occlusion (tMCAO). Injection of SiO4@SPIONs-EPCs and followed by magnetic field treatment showed improved neurobehavioral outcomes, reduced brain atrophic volume, increased microvessel density and VEGF expression in the ischemic perifocal region compared to groups without magnetic field treatment (p < 0.05). Our results demonstrated that exterior magnetic field could guide SiO4@SPIONs-EPCs to ischemic region and enhance therapeutic effect, suggesting that magnetic-guided SiO4@SPIONs-EPCs delivery is a promising approach in cerebral ischemic therapy.
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Eu(3+)-induced aggregates of diblock copolymers and their photoluminescent property.
J Colloid Interface Sci
PUBLISHED: 01-09-2013
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A general protocol to prepare photoluminescent polymeric aggregates with multiple morphological structures was proposed in this article. The amphiphilic diblock copolymer, polystyrene-block-poly (acrylic acid) (PS-b-PAA) which acted as the polymer ligand, was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Eu(3+) ions were selected as the cross-linkers to coordinate with the carboxyl groups along PAA segments of the diblock copolymer, resulting in cross-linked PAA networks as the core. At the same time, PS coronas still kept their solubility to the solvent phase, preventing the precipitation of the complex. The obtained aggregates dispersed well in dimethyl formamide (DMF) instead of precipitation occurred in complex systems between non-block copolymers and lanthanide ions. It is the first time that the aggregates with rich morphological structures, including ordinary micelles, rod-wrapped micelles, sun-shaped micelles, vesicles and large compound micelles (LCMs), were obtained by adjusting the molar ratio or the concentration of Eu(3+) ions and diblock copolymer. Importantly, the aggregates have enhanced photoluminescent properties via the coordination between Eu(3+) and diblock copolymer at their optimal ratio. The obtained aggregates are convenient for further processing, such as spin-coating and casting. This strategy can also be applied to other coordination systems between diblock copolymers and lanthanide ions.
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Lipid Raft Is Required for PSGL-1 Ligation Induced HL-60 Cell Adhesion on ICAM-1.
PLoS ONE
PUBLISHED: 01-01-2013
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P-selectin glycoprotein ligand-1 (PSGL-1) and integrins are adhesion molecules that play critical roles in host defense and innate immunity. PSGL-1 mediates leukocyte rolling and primes leukocytes for integrin-mediated adhesion. However, the mechanism that PSGL-1 as a rolling receptor in regulating integrin activation has not been well characterized. Here, we investigate the function of lipid raft in regulating PSGL-1 induced ?2 integrin-mediated HL-60 cells adhesion. PSGL-1 ligation with antibody enhances the ?2 integrin activation and ?2 integrin-dependent adhesion to ICAM-1. Importantly, with the treatment of methyl-?-cyclodextrin (M?CD), we confirm the role of lipid raft in regulating the activation of ?2 integrin. Furthermore, we find that the protein level of PSGL-1 decreased in raft fractions in M?CD treated cells. PSGL-1 ligation induces the recruitment of spleen tyrosine kinase (Syk), a tyrosine kinase and Vav1 (the pivotal downstream effector of Syk signaling pathway involved in cytoskeleton regulation) to lipid raft. Inhibition of Syk activity with pharmacologic inhibitor strongly reduces HL-60 cells adhesion, implicating Syk is crucial for PSGL-1 mediated ?2 integrin activation. Taken together, we report that ligation of PSGL-1 on HL-60 cells activates ?2 integrin, for which lipid raft integrity and Syk activation are responsible. These ?ndings have shed new light on the mechanisms that connect leukocyte initial rolling with subsequent adhesion.
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Surgery-related thrombosis critically affects the brain infarct volume in mice following transient middle cerebral artery occlusion.
PLoS ONE
PUBLISHED: 01-01-2013
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Transient middle cerebral artery occlusion (tMCAO) model is widely used to mimic human focal ischemic stroke in order to study ischemia/reperfusion brain injury in rodents. In tMCAO model, intraluminal suture technique is widely used to achieve ischemia and reperfusion. However, variation of infarct volume in this model often requires large sample size, which hinders the progress of preclinical research. Our previous study demonstrated that infarct volume was related to the success of reperfusion although the reason remained unclear. The aim of present study is to explore the relationship between focal thrombus formation and model reproducibility with respect to infarct volume. We hypothesize that suture-induced thrombosis causes infarct volume variability due to insufficient reperfusion after suture withdrawal. Seventy-two adult male CD-1 mice underwent 90 minutes of tMCAO with or without intraperitoneal administration of heparin. Dynamic synchrotron radiation microangiography (SRA) and laser speckle contrast imaging (LSCI) were performed before and after tMCAO to observe the cerebral vascular morphology and to measure the cerebral blood flow in vivo. Infarct volume and neurological score were examined to evaluate severity of ischemic brain injury. We found that the rate of successful reperfusion was much higher in heparin-treated mice compared to that in heparin-free mice according to the result of SRA and LSCI at 1 and 3 hours after suture withdrawal (p<0.05). Pathological features and SRA revealed that thrombus formed in the internal carotid artery, middle cerebral artery or anterior cerebral artery, which blocked reperfusion following tMCAO. LSCI showed that cortical collateral circulation could be disturbed by thrombi. Our results demonstrated that suture-induced thrombosis was a critical element, which affects the success of reperfusion. Appropriate heparin management provides a useful approach for improving reproducibility of reperfusion model in mice.
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MicroRNAs as master regulators of the plant NB-LRR defense gene family via the production of phased, trans-acting siRNAs.
Genes Dev.
PUBLISHED: 12-14-2011
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Legumes and many nonleguminous plants enter symbiotic interactions with microbes, and it is poorly understood how host plants respond to promote beneficial, symbiotic microbial interactions while suppressing those that are deleterious or pathogenic. Trans-acting siRNAs (tasiRNAs) negatively regulate target transcripts and are characterized by siRNAs spaced in 21-nucleotide (nt) "phased" intervals, a pattern formed by DICER-LIKE 4 (DCL4) processing. A search for phased siRNAs (phasiRNAs) found at least 114 Medicago loci, the majority of which were defense-related NB-LRR-encoding genes. We identified three highly abundant 22-nt microRNA (miRNA) families that target conserved domains in these NB-LRRs and trigger the production of trans-acting siRNAs. High levels of small RNAs were matched to >60% of all ?540 encoded Medicago NB-LRRs; in the potato, a model for mycorrhizal interactions, phasiRNAs were also produced from NB-LRRs. DCL2 and SGS3 transcripts were also cleaved by these 22-nt miRNAs, generating phasiRNAs, suggesting synchronization between silencing and pathogen defense pathways. In addition, a new example of apparent "two-hit" phasiRNA processing was identified. Our data reveal complex tasiRNA-based regulation of NB-LRRs that potentially evolved to facilitate symbiotic interactions and demonstrate miRNAs as master regulators of a large gene family via the targeting of highly conserved, protein-coding motifs, a new paradigm for miRNA function.
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Massive analysis of rice small RNAs: mechanistic implications of regulated microRNAs and variants for differential target RNA cleavage.
Plant Cell
PUBLISHED: 12-09-2011
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Small RNAs have a variety of important roles in plant development, stress responses, and other processes. They exert their influence by guiding mRNA cleavage, translational repression, and chromatin modification. To identify previously unknown rice (Oryza sativa) microRNAs (miRNAs) and those regulated by environmental stress, 62 small RNA libraries were constructed from rice plants and used for deep sequencing with Illumina technology. The libraries represent several tissues from control plants and plants subjected to different environmental stress treatments. More than 94 million genome-matched reads were obtained, resulting in more than 16 million distinct small RNA sequences. This allowed an evaluation of ~400 annotated miRNAs with current criteria and the finding that among these, ~150 had small interfering RNA-like characteristics. Seventy-six new miRNAs were found, and miRNAs regulated in response to water stress, nutrient stress, or temperature stress were identified. Among the new examples of miRNA regulation were members of the same miRNA family that were differentially regulated in different organs and had distinct sequences Some of these distinct family members result in differential target cleavage and provide new insight about how an agriculturally important rice phenotype could be regulated in the panicle. This high-resolution analysis of rice miRNAs should be relevant to plant miRNAs in general, particularly in the Poaceae.
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Why a Bayesian approach to safety analysis in pharmacovigilance is important.
Pharm Stat
PUBLISHED: 12-05-2011
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Large databases of routinely collected data are a valuable source of information for detecting potential associations between drugs and adverse events (AE). A pharmacovigilance system starts with a scan of these databases for potential signals of drug-AE associations that will subsequently be examined by experts to aid in regulatory decision-making. The signal generation process faces some key challenges: (1) an enormous volume of drug-AE combinations need to be tested (i.e. the problem of multiple testing); (2) the results are not in a format that allows the incorporation of accumulated experience and knowledge for future signal generation; and (3) the signal generation process ignores information captured from other processes in the pharmacovigilance system and does not allow feedback. Bayesian methods have been developed for signal generation in pharmacovigilance, although the full potential of these methods has not been realised. For instance, Bayesian hierarchical models will allow the incorporation of established medical and epidemiological knowledge into the priors for each drug-AE combination. Moreover, the outputs from this analysis can be incorporated into decision-making tools to help in signal validation and posterior actions to be taken by the regulators and companies. We discuss in this paper the apparent advantage of the Bayesian methods used in safety signal generation and the similarities and differences between the two widely used Bayesian methods. We will also propose the use of Bayesian hierarchical models to address the three key challenges and discuss the reasons why Bayesian methodology still have not been fully utilised in pharmacovigilance activities.
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A review of risk measures in pharmacoepidemiology with tips for statisticians in the pharmaceutical industry.
Pharm Stat
PUBLISHED: 11-30-2011
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Pharmacoepidemiology is the study of the therapeutic effects, risk, and use of drugs in large populations, which applies epidemiological methods and reasoning. As reflected in the recent strengthening of the pharmacovigilance legislation in Europe, greater attention has been placed to epidemiological research in response to an increasing call by the public for further post-marketing studies on the safety and efficacy of drugs. Various measures of risk are used in pharmacoepidemiology to quantify the probability of experiencing an adverse outcome and capture the relative increases in risk between treated and untreated populations: cumulative incidence, incidence rate, absolute risk reduction, relative risk, odds ratio, incidence rate ratio, and time to event outcomes. We review in this paper the commonly used measures of risk in pharmacoepidemiology and provide some practical tips for the industry statistician.
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Roles of DCL4 and DCL3b in rice phased small RNA biogenesis.
Plant J.
PUBLISHED: 11-23-2011
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Higher plants have evolved multiple proteins in the RNase III family to produce and regulate different classes of small RNAs with specialized molecular functions. In rice (Oryza sativa), numerous genomic clusters are targeted by one of two microRNAs (miRNAs), miR2118 and miR2275, to produce secondary small interfering RNAs (siRNAs) of either 21 or 24 nucleotides in a phased manner. The biogenesis requirements or the functions of the phased small RNAs are completely unknown. Here we examine the rice Dicer-Like (DCL) family, including OsDCL1, -3a, -3b and -4. By deep sequencing of small RNAs from different tissues of the wild type and osdcl4-1, we revealed that the processing of 21-nucleotide siRNAs, including trans-acting siRNAs (tasiRNA) and over 1000 phased small RNA loci, was largely dependent on OsDCL4. Surprisingly, the processing of 24-nucleotide phased small RNA requires the DCL3 homolog OsDCL3b rather than OsDCL3a, suggesting functional divergence within DCL3 family. RNA ligase-mediated 5 rapid amplification of cDNA ends and parallel analysis of RNA ends (PARE)/degradome analysis confirmed that most of the 21- and 24-nucleotide phased small RNA clusters were initiated from the target sites of miR2118 and miR2275, respectively. Furthermore, the accumulation of the two triggering miRNAs requires OsDCL1 activity. Finally, we show that phased small RNAs are preferentially produced in the male reproductive organs and are likely to be conserved in monocots. Our results revealed significant roles of OsDCL4, OsDCL3b and OsDCL1 in the 21- and 24-nucleotide phased small RNA biogenesis pathway in rice.
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Ubiquitination of heat shock protein 27 is mediated by its interaction with Smad ubiquitination regulatory factor 2 in A549 cells.
Exp. Lung Res.
PUBLISHED: 10-03-2011
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Smad ubiquitination regulatory factor 2 (Smurf2) is a crucial part of the ubiquitin-proteasome pathway (UPP) that regulates cellular signal transduction via ubiquitin-dependent degradation of some substrates and receptors. The biological function of Smurf2 in lung diseases, however, is not clear. In this study, the authors found that overexpression of Smurf2 altered the subcellular localization and distribution of heat shock protein 27 (HSP27), and induced a decrease of HSP27 protein levels through HSP27 degradation by the UPP in human lung adenocarcinoma epithelial cell line A549. Colocalized assay using confocal microscopy and coimmunoprecipitated reciprocally by either antibody indicated the interaction between Smurf2 and HSP27, which suggested that Smurf2 mediated ubiquitylation-dependent degradation of HSP27 through their interaction in A549 cells.
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Nonparametric estimation for cumulative duration of adverse events.
Biom J
PUBLISHED: 09-15-2011
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Analysis of adverse events (AE) for drug safety assessment presents challenges to statisticians in observational studies as well as in clinical trials since AEs are typically recurrent with varying duration and severity. Routine analyses often concentrate on the number of patients who had at least one occurrence of a specific AE or a group of AEs, or the time to occurrence of the first event. We argue that other information in AE data particularly cumulative duration of events is also important, particularly for benefit-risk assessment. We propose a nonparametric method to estimate the mean cumulative duration (MCD) based on the nonparametric cumulative mean function estimate, together with a robust estimate for the variance of the estimate, as in Lawless and Nadeau (1995). This approach can be easily used to analyze multiple, overlapped and severity weighted AE durations. This method can also be used for estimating the difference between two MCDs. Estimation in the presence of censoring due to informative dropouts and/or a terminal event is also considered. The method can be implemented in standard softwares such as SAS. We illustrate the use of the method with a numerical example. Small sample properties of this approach are examined via simulation.
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Genome sequence of Agrobacterium tumefaciens strain F2, a bioflocculant-producing bacterium.
J. Bacteriol.
PUBLISHED: 09-15-2011
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Agrobacterium tumefaciens F2 is an efficient bioflocculant-producing bacterium. But the genes related to the metabolic pathway of bioflocculant biosynthesis in strain F2 are unknown. We present the draft genome of A. tumefaciens F2. It could provide further insight into the biosynthetic mechanism of polysaccharide-like bioflocculant in strain F2.
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Three-dimensional paper-based electrochemiluminescence immunodevice for multiplexed measurement of biomarkers and point-of-care testing.
Biomaterials
PUBLISHED: 08-28-2011
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In this work, electrochemiluminescence (ECL) immunoassay was introduced into the recently proposed microfluidic paper-based analytical device (?PADs) based on directly screen-printed electrodes on paper for the very first time. The screen-printed paper-electrodes will be more important for further development of this paper-based ECL device in simple, low-cost and disposable application than commercialized ones. To further perform high-performance, high-throughput, simple and inexpensive ECL immunoassay on ?PAD for point-of-care testing, a wax-patterned three-dimensional (3D) paper-based ECL device was demonstrated for the very first time. In this 3D paper-based ECL device, eight carbon working electrodes including their conductive pads were screen-printed on a piece of square paper and shared the same Ag/AgCl reference and carbon counter electrodes on another piece of square paper after stacking. Using typical tris-(bipyridine)-ruthenium (?) - tri-n-propylamine ECL system, the application test of this 3D paper-based ECL device was performed through the diagnosis of four tumor markers in real clinical serum samples. With the aid of a facile device-holder and a section-switch assembled on the analyzer, eight working electrodes were sequentially placed into the circuit to trigger the ECL reaction in the sweeping range from 0.5 to 1.1 V at room temperature. In addition, this 3D paper-based ECL device can be easily integrated and combined with the recently emerging paper electronics to further develop simple, sensitive, low-cost, disposable and portable ?PAD for point-of-care testing, public health and environmental monitoring in remote regions, developing or developed countries.
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Opportunities for minimization of confounding in observational research.
Pharm Stat
PUBLISHED: 07-01-2011
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Observational epidemiological studies are increasingly used in pharmaceutical research to evaluate the safety and effectiveness of medicines. Such studies can complement findings from randomized clinical trials by involving larger and more generalizable patient populations by accruing greater durations of follow-up and by representing what happens more typically in the clinical setting. However, the interpretation of exposure effects in observational studies is almost always complicated by non-random exposure allocation, which can result in confounding and potentially lead to misleading conclusions. Confounding occurs when an extraneous factor, related to both the exposure and the outcome of interest, partly or entirely explains the relationship observed between the study exposure and the outcome. Although randomization can eliminate confounding by distributing all such extraneous factors equally across the levels of a given exposure, methods for dealing with confounding in observational studies include a careful choice of study design and the possible use of advanced analytical methods. The aim of this paper is to introduce some of the approaches that can be used to help minimize the impact of confounding in observational research to the reader working in the pharmaceutical industry.
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hElp3 directly modulates the expression of HSP70 gene in HeLa cells via HAT activity.
PLoS ONE
PUBLISHED: 06-30-2011
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Human Elongator complex, which plays a key role in transcript elongation in vitro assay, is incredibly similar in either components or function to its yeast counterpart. However, there are only a few studies focusing on its target gene characterization in vivo. We studied the effect of down-regulation of the human elongation protein 3 (hELP3) on the expression of HSP70 through antisense strategy. Transfecting antisense plasmid p1107 into HeLa cells highly suppressed hELP3 expression, and substantially reduced expression of HSP70 mRNA and protein. Furthermore, chromatin immunoprecipitation assay (ChIP Assay) revealed that hElp3 participates in the transcription elongation of HSPA1A in HeLa cells. Finally, complementation and ChIP Assay in yeast showed that hElp3 can not only complement the growth and slow activation of HSP70 (SSA3) gene transcription, but also directly regulates the transcription of SSA3. On the contrary, these functions are lost when the HAT domain is deleted from hElp3. These data suggest that hElp3 can regulate the transcription of HSP70 gene, and the HAT domain of hElp3 is essential for this function. These findings now provide novel insights and evidence of the functions of hELP3 in human cells.
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The Medicago genome provides insight into the evolution of rhizobial symbioses.
Nevin D Young, Frédéric Debellé, Giles E D Oldroyd, Rene Geurts, Steven B Cannon, Michael K Udvardi, Vagner A Benedito, Klaus F X Mayer, Jérôme Gouzy, Heiko Schoof, Yves Van de Peer, Sebastian Proost, Douglas R Cook, Blake C Meyers, Manuel Spannagl, Foo Cheung, Stéphane De Mita, Vivek Krishnakumar, Heidrun Gundlach, Shiguo Zhou, Joann Mudge, Arvind K Bharti, Jeremy D Murray, Marina A Naoumkina, Benjamin Rosen, Kevin A T Silverstein, Haibao Tang, Stephane Rombauts, Patrick X Zhao, Peng Zhou, Valérie Barbe, Philippe Bardou, Michael Bechner, Arnaud Bellec, Anne Berger, Hélène Berges, Shelby Bidwell, Ton Bisseling, Nathalie Choisne, Arnaud Couloux, Roxanne Denny, Shweta Deshpande, Xinbin Dai, Jeff J Doyle, Anne-Marie Dudez, Andrew D Farmer, Stéphanie Fouteau, Carolien Franken, Chrystel Gibelin, John Gish, Steven Goldstein, Alvaro J González, Pamela J Green, Asis Hallab, Marijke Hartog, Axin Hua, Sean J Humphray, Dong-Hoon Jeong, Yi Jing, Anika Jöcker, Steve M Kenton, Dong-Jin Kim, Kathrin Klee, Hongshing Lai, Chunting Lang, Shaoping Lin, Simone L Macmil, Ghislaine Magdelenat, Lucy Matthews, Jamison McCorrison, Erin L Monaghan, Jeong-Hwan Mun, Fares Z Najar, Christine Nicholson, Céline Noirot, Majesta O'Bleness, Charles R Paule, Julie Poulain, Florent Prion, Baifang Qin, Chunmei Qu, Ernest F Retzel, Claire Riddle, Erika Sallet, Sylvie Samain, Nicolas Samson, Iryna Sanders, Olivier Saurat, Claude Scarpelli, Thomas Schiex, Béatrice Ségurens, Andrew J Severin, D Janine Sherrier, Ruihua Shi, Sarah Sims, Susan R Singer, Senjuti Sinharoy, Lieven Sterck, Agnès Viollet, Bing-Bing Wang, Keqin Wang, Mingyi Wang, Xiaohong Wang, Jens Warfsmann, Jean Weissenbach, Doug D White, Jim D White, Graham B Wiley, Patrick Wincker, Yanbo Xing, Limei Yang, Ziyun Yao, Fu Ying, Jixian Zhai, Liping Zhou, Antoine Zuber, Jean Dénarié, Richard A Dixon, Gregory D May, David C Schwartz, Jane Rogers, Francis Quetier, Christopher D Town, Bruce A Roe.
Nature
PUBLISHED: 06-13-2011
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Legumes (Fabaceae or Leguminosae) are unique among cultivated plants for their ability to carry out endosymbiotic nitrogen fixation with rhizobial bacteria, a process that takes place in a specialized structure known as the nodule. Legumes belong to one of the two main groups of eurosids, the Fabidae, which includes most species capable of endosymbiotic nitrogen fixation. Legumes comprise several evolutionary lineages derived from a common ancestor 60 million years ago (Myr ago). Papilionoids are the largest clade, dating nearly to the origin of legumes and containing most cultivated species. Medicago truncatula is a long-established model for the study of legume biology. Here we describe the draft sequence of the M. truncatula euchromatin based on a recently completed BAC assembly supplemented with Illumina shotgun sequence, together capturing ?94% of all M. truncatula genes. A whole-genome duplication (WGD) approximately 58 Myr ago had a major role in shaping the M. truncatula genome and thereby contributed to the evolution of endosymbiotic nitrogen fixation. Subsequent to the WGD, the M. truncatula genome experienced higher levels of rearrangement than two other sequenced legumes, Glycine max and Lotus japonicus. M. truncatula is a close relative of alfalfa (Medicago sativa), a widely cultivated crop with limited genomics tools and complex autotetraploid genetics. As such, the M. truncatula genome sequence provides significant opportunities to expand alfalfas genomic toolbox.
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Biological improvement on combined mycelial pellet for aniline treatment by tourmaline in SBR process.
Bioresour. Technol.
PUBLISHED: 05-10-2011
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As a biomass carrier, mycelial pellet of Aspergillus niger Y3 was used to immobilize the aniline-degrading bacterium Acinetobacter calcoaceticus JH-9 and the mix culture of the COD rapid degrading bacteria in this study. Tourmaline was added to this system in order to improve the aniline removal performance using combined mycelial pellet. Flask experiments were performed to investigate the promotion mechanism. The results showed that the start-up time was shorted from 7 cycles to only 1 cycle. The aniline and COD concentration in effluent were much lower in the tourmaline-adding system. It was suggested that tourmaline could enhance the number and activity of the aniline-degrading bacteria immobilized on the mycelial pellet. Therefore, the performance of mycelial pellet as a biomass carrier could be improved by tourmaline.
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Mimotope ELISA for detection of broad spectrum antibody against avian H5N1 influenza virus.
PLoS ONE
PUBLISHED: 04-12-2011
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We have raised a panel of broad spectrum neutralizing monoclonal antibodies against the highly pathogenic H5N1 avian influenza virus, which neutralize the infectivity of, and afford protection against infection by, most of the major genetic groups of the virus evolved since 1997. Peptide mimics reactive with one of these broad spectrum H5N1 neutralizing antibodies, 8H5, were identified from random phage display libraries.
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Plk1-mediated phosphorylation of UAP56 regulates the stability of UAP56.
Mol. Biol. Rep.
PUBLISHED: 03-25-2011
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Polo-like kinase 1 (Plk1) is a conserved serine/threonine protein kinase that plays pivotal roles during the cell cycle and cell proliferation. Although a number of important targets have been identified, the mechanism of Plk1-regulated pathways and the bulk of the Plk1 interactome are largely unknown. Here, we demonstrate that Plk1 interacts with the DExH/D RNA helicase, UAP56. The protein levels of UAP56 and Plk1 are inversely correlated during the cell cycle. We also show that Plk1 phosphorylates UAP56 in vitro and in vivo and that Plk1-dependent phosphorylation of UAP56 triggers ubiquitination and degradation of UAP56 through proteasomes. This result suggests that Plk1-mediated phosphorylation of UAP56 regulates the stability of UAP56. Our results will be helpful in further understanding mRNA metabolism, cell cycle progression, and the link between mRNA metabolism and cellular function.
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Histopathological and biochemical alternations of the heart induced by acute cadmium exposure in the freshwater crab Sinopotamon yangtsekiense.
Chemosphere
PUBLISHED: 03-01-2011
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Cadmium (Cd) is a highly toxic element in water. Its toxicity has been attributed to oxidative stress mediated by free radicals. Here we investigated the effects of Cd on the histopathology, antioxidant enzymes and lipid peroxidation of crustacean heart. The freshwater crabs Sinopotamon yangtsekiense were exposed to different concentrations of Cd for 1, 3, 5 and 7d. After exposure, histological abnormalities were discovered, including myocardial edema, vacuolar and vitreous degeneration, and infiltration of inflammatory cells. Additionally, alterations in nuclei, mitochondria, rough endoplasmic reticulum as well as myofibrils were observed. Meanwhile, superoxide dismutase (SOD) activity was significantly increased after Cd exposure. Catalase (CAT) activity was only increased in the group exposed to 14.50 mg L(-1) Cd on day 5 and decreased with increasing Cd concentration and exposure time. Glutathione peroxidase (GPx) activity was increased in groups treated with 29.00, 58.00 and 116.00 mg L(-1) on days 1 and 3, and decreased thereafter. Besides, malondialdehyde (MDA) levels were significantly increased after 3d of Cd exposure at all the indicated concentrations. These results showed that acute Cd exposure led to harmful effects on the histology of crab heart, which are most likely linked to Cd-induced oxidative stress.
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Viability and proliferation potential of adipose-derived stem cells following labeling with a positron-emitting radiotracer.
Eur. J. Nucl. Med. Mol. Imaging
PUBLISHED: 02-01-2011
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Adipose-derived stem cells (ASCs) have promising potential in regenerative medicine and cell therapy. Our objective is to examine the biological function of the labeled stem cells following labeling with a readily available positron emission tomography (PET) tracer, (18)F-fluoro-2-deoxy-D: -glucose (FDG). In this work we characterize labeling efficiency through assessment of FDG uptake and retention by the ASCs and the effect of FDG on cell viability, proliferation, transdifferentiation, and cell function in vitro using rat ASCs.
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High prevalence of HIV type 1 subtype B among heterosexuals in Western Hubei, Central China: bridging the epidemic into the general population.
AIDS Res. Hum. Retroviruses
PUBLISHED: 01-27-2011
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A molecular epidemiological investigation (n = 62) conducted in western Hubei, Central China, revealed that HIV-1 subtype B (Thailand variant of subtype B) predominated not only among former plasma donors (FPDs) (29/29, 100%) but also among heterosexuals (27/31, 87%), suggesting that subtype B appears to bridge the spread from FPDs in the general population in this particular area in Central China.
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Statistical aspects in comparative benefit-risk assessment: challenges and opportunities for pharmaceutical statisticians.
Pharm Stat
PUBLISHED: 01-13-2011
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Benefit-risk assessment is a fundamental element of drug development with the aim to strengthen decision making for the benefit of public health. Appropriate benefit-risk assessment can provide useful information for proactive intervention in health care settings, which could save lives, reduce litigation, improve patient safety and health care outcomes, and furthermore, lower overall health care costs. Recent development in this area presents challenges and opportunities to statisticians in the pharmaceutical industry. We review the development and examine statistical issues in comparative benefit-risk assessment. We argue that a structured benefit-risk assessment should be a multi-disciplinary effort involving experts in clinical science, safety assessment, decision science, health economics, epidemiology and statistics. Well planned and conducted analyses with clear consideration on benefit and risk are critical for appropriate benefit-risk assessment. Pharmaceutical statisticians should extend their knowledge to relevant areas such as pharmaco-epidemiology, decision analysis, modeling, and simulation to play an increasingly important role in comparative benefit-risk assessment.
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Performance of enhanced biological SBR process for aniline treatment by mycelial pellet as biomass carrier.
Bioresour. Technol.
PUBLISHED: 09-06-2010
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Mycelial pellet of Aspergillus niger Y3 was used as a biomass carrier to immobilize the aniline-degrading bacterium, Acinetobacter calcoaceticus JH-9 and the mix culture of the COD rapid degradation bacteria. In order to investigate its removal effect on aniline and COD, the combined mycelial pellets were applied in the SBR. Comparison of the performances was conducted between another SBR inoculated with sole strain JH-9 and the above SBR. The results showed that the stable degradations of aniline and COD were observed in both reactors. In the SBR with combined mycelial pellet, the biological removal efficiency was about 0.9 mg aniline/(L·d). It was much higher than that in the activated sludge reactor. Meanwhile, the performances of the sedimentation velocity, liquid-solid phase separation and the effluent quality were better in the SBR. According to SEM images and PCR-DGGE analysis, the species immobilized on the biomass carrier were more predominant in this system.
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Many-to-one comparison after sample size reestimation for trials with multiple treatment arms and treatment selection.
J Biopharm Stat
PUBLISHED: 08-20-2010
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Sample size reestimation (SSRE) provides a useful tool to change the sample size when an interim look reveals that the original sample size is inadequate. To control the overall type I error, for testing one hypothesis, several approaches have been proposed to construct a statistic so that its distribution is independent to the SSRE under the null hypothesis. We considered a similar approach for comparisons between multiple treatment arms and placebo, allowing the change of sample sizes in all arms depending on interim information. A construction of statistics similar to that for a single hypothesis test is proposed. When the changes of sample sizes in different arms are proportional, we show that one-step and stepwise Dunnett tests can be used directly on statistics constructed in the proposed way. The approach can also be applied to clinical trials with SSRE and treatment selection at interim. The proposed approach is evaluated with simulations under different situations.
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[Differentiation of bone marrow mesenchymal stem cells into nucleus pulposus-like cells transfected by SOX9 eukaryotic expression vector in vitro].
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi
PUBLISHED: 08-11-2010
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The biological treatment of intervertebral disc degeneration becomes a research hotspot in recent years. It is necessary to find an effective approach to induce bone marrow mesenchymal stem cells (BMSCs) differentiate to disc cells which could make application of cell transplantation as a treatment of intervertebral disc degeneration. To investigate the effects of the recombinant plasmid pcDNA3.1IE-SOX9Flag on differentiation of rabbit BMSCs into nucleus pulposus-like cells.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.