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Find video protocols related to scientific articles indexed in Pubmed.
Zinc and the prooxidant heart failure phenotype.
J. Cardiovasc. Pharmacol.
PUBLISHED: 10-08-2014
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: Neurohormonal activation with attendant aldosteronism contributes to the clinical appearance of congestive heart failure (CHF). Aldosteronism is intrinsically coupled to Zn and Ca dyshomeostasis, in which consequent hypozincemia compromises Zn homeostasis and Zn-based antioxidant defenses that contribute to the CHF prooxidant phenotype. Ionized hypocalcemia leads to secondary hyperparathyroidism with parathyroid hormone-mediated Ca overloading of diverse cells, including cardiomyocytes. When mitochondrial Ca overload exceeds a threshold, myocyte necrosis follows. The reciprocal regulation involving cytosolic free [Zn]i as antioxidant and [Ca]i as prooxidant can be uncoupled in favor of Zn-based antioxidant defenses. Increased [Zn]i acts as a multifaceted antioxidant by: (1) inhibiting Ca entry through L-type channels and hence cardioprotectant from the Ca-driven mitochondriocentric signal-transducer effector pathway to nonischemic necrosis, (2) serving as catalytic regulator of Cu/Zn-superoxide dismutase, and (3) activating its cytosolic sensor, metal-responsive transcription factor that regulates the expression of relevant antioxidant defense genes. Albeit present in subnanomolar range, increased cytosolic free [Zn]i enhances antioxidant capacity that confers cardioprotection. It can be achieved exogenously by ZnSO4 supplementation or endogenously using a ?3-receptor agonist (eg, nebivolol) that enhances NO generation to release inactive cytosolic Zn bound to metallothionein. By recognizing the pathophysiologic relevance of Zn dyshomeostasis in the prooxidant CHF phenotype and by exploiting the pharmacophysiologic potential of [Zn]i as antioxidant, vulnerable cardiomyocytes under assault from neurohormonal activation can be protected and the myocardium spared from adverse structural remodeling.
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miR-124/ATF-6, A Novel Lifespan Extension Pathway of Astragalus Polysaccharide in C. elegans.
J. Cell. Biochem.
PUBLISHED: 09-04-2014
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MicroRNAs (miRNAs), especially evolutionarily conserved miRNAs play critical roles in regulating various biological process. However, the functions of conserved miRNAs in longevity are still largely unknown. Astragalus polysaccharide (APS) was recently shown to extend lifespan of Caenorhabditis elegans (C. elegans), but its molecular mechanisms have not been fully understood. In the present study, we characterize that microRNA mediated a novel longevity pathway of APS in C. elegans. We found that APS markedly extended the lifespan of C. elegans at the second and the fourth stages. A highly conserved miRNA miR-124 was significantly upregulated in APS-treated C. elegans. Overexpression miR-124 caused the lifespan extension of C. elegans and vice versa, indicating miR-124 regulates the longevity of C. elegans. Using luciferase assay, atf-6 was established as a target gene of miR-124 which acting on three binding sites at atf-6 3'UTR. Consistently, agomir-cel-miR-124 was also shown to inhibit ATF-6 expression in C. elegans. APS-treated C. elegans showed the down-regulation of atf-6 at protein level. Furthermore, the knockdown of atf-6 by RNAi extended the lifespan of C. elegans, indicating atf-6 regulated by miR-124 contributes to lifespan extension. Taken together, miR-124 regulating ATF-6 is a new potential longevity signal pathway, which underlies the lifespan-extending effects of APS in C. elegans. J. Cell. Biochem. © 2014 Wiley Periodicals, Inc.
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Platelet-derived growth factor blockade on cardiac remodeling following infarction.
Mol. Cell. Biochem.
PUBLISHED: 08-23-2014
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Cardiac repair and remodeling occur following myocardial infarction (MI). Our previous study demonstrated that platelet-derived growth factor (PDGF)-A/-D and PDGF receptors (PDGFR) are increased in the infarcted heart, with cells expressing PDGFR primarily endothelial and fibroblast-like cells. In the present study, we tested the hypothesis that PDGF contributes to cardiac angiogenesis and fibrogenesis post-MI. Rats with experimental MI were treated with either a PDGFR antagonist (Imatinib, 40 mg/kg/day) or vehicle by gavage, and sham-operated rats served as the controls. Cardiac fibrogenesis, angiogenesis, and ventricular function were detected at weeks 1 and 4 post-MI. We found that (1) transforming growth factor (TGF)-?1, tissue inhibitors of metalloproteinases (TIMP)-1/-2, and type I collagen mRNA were all significantly increased in the infarcted heart at week 1 post-MI, while PDGFR blockade significantly reduced these fibrogenic mediators in the noninfarcted myocardium as compared to controls; (2) fibrosis developed in both the infarcted and noninfarcted myocardium at week 4 with PDGFR blockade significantly suppressing collagen volume in the noninfarcted myocardium; (3) angiogenesis was activated in the infarcted myocardium, particularly at week 1, and was not altered by treatment with imatinib; and (4) ventricular dysfunction was evident in MI rats at week 4, and mildly improved with imatinib treatment. These observations indicated that PDGF can contribute to the development of cardiac interstitial fibrosis in the noninfarcted myocardium, but does not alter scar formation in the infarcted myocardium. Further, this study suggests the potential therapeutic effects of PDGFR blockade on interstitial fibrosis of the infarcted heart.
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CD82 Restrains Pathological Angiogenesis by Altering Lipid Raft Clustering and CD44 Trafficking in Endothelial Cells.
Circulation
PUBLISHED: 08-22-2014
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Angiogenesis is crucial for many pathological processes and becomes a therapeutic strategy against diseases ranging from inflammation to cancer. The regulatory mechanism of angiogenesis remains unclear. Although tetraspanin CD82 is widely expressed in various endothelial cells (ECs), its vascular function is unknown.
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[Antimicrobial resistance characteristics of and disinfectant-resistant gene distribution in Staphylococcus aureus isolates from male urogenital tract infection].
Zhonghua Nan Ke Xue
PUBLISHED: 08-07-2014
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To study the antibiotic- and disinfectant-resistance features of and disinfectant-resistant gene distribution in Staphylococcus aureus (Sa) isolated from the urogenital tract of male patients with urogenital tract infection (UTI). total of 152 Sa isolates were collected from the urethral discharge specimens from male UTI patients. The minimum inhibition concentration (MIC) of antimicrobial agents and disinfectants commonly used against Sa were tested by standard ager dilution; the methicillin-resistant Sa (MRSA) isolates detected by cefoxitin disk diffusion and mecA gene amplification; Staphylococcal cassette chromosome mec (SCCmec) genotyping performed by multiplex PCR; the disinfectants gene qac (quaternary ammonium compound) amplified by PCR; and the clonal relatedness of qacA/B-positive MRSA isolates investigated by pulsed-field gel electrophoresis (PFGE).
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7, 8-Dihydroxyflavone induces synapse expression of AMPA GluA1 and ameliorates cognitive and spine abnormalities in a mouse model of fragile X syndrome.
Neuropharmacology
PUBLISHED: 06-14-2014
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Fragile X syndrome (FXS) is characterized by immature dendritic spine architectures and cognitive impairment. 7, 8-Dihydroxyflavone (7, 8-DHF) has recently been identified as a high affinity tropomyosin receptor kinase B (TrkB) agonist. The purpose of this paper was to examine the utility of 7, 8-DHF as an effective pharmacotherapeutic agent that targets dendritic pathology and cognitive impairments in FXS mutant. We synthesized pharmacologic, behavioral, and biochemical approaches to examine the effects of 7, 8-DHF on spatial and fear memory functions, and morphological spine abnormalities in fragile X mental retardation 1 (Fmr1) gene knock-out mice. The study found that 4 weeks of treatment with 7, 8-DHF improved spatial and fear memory, and ameliorated morphological spine abnormalities including the number and elongation of spines in the hippocampus and amygdala. Further mechanism analysis revealed that 7, 8-DHF enhanced the expression of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) GluA1 receptor, but reduced the normal levels of GluA2 at the synapses in Fmr1. Potentially related to drug-induced changes in AMPA receptor subunits, 7, 8-DHF at the synapses led to phosphorylation of specific serine sites on subunits Ser818 and Ser813 of GluA1, and Ser880 of GluA2, as well as phosphorylation of TrkB, calcium/calmodulin-dependent protein kinase II, and protein kinase C. However, 7, 8-DHF neither affected behavioral performance nor increased TrkB phosphorylation in WT mice, which suggested that it had FXS-specific correcting effect. Altogether, these results demonstrated that 7, 8-DHF improved learning and memory, and reduced abnormalities in spine morphology, thus providing a potential pharmacotherapeutic strategy for FXS.
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A systems biology approach to study the biology characteristics of esophageal squamous cell carcinoma by integrating microRNA and messenger RNA expression profiling.
Cell Biochem. Biophys.
PUBLISHED: 06-14-2014
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Esophageal squamous cell carcinoma (ESCC) is one of the most malignant tumors. The aim of this study was to investigate the biology characteristics of ESCC by analyzing microRNA and mRNA expression profile. We used BRB-array tools to analyze the deregulated microRNA and mRNA between esophageal squamous cell carcinomas and paired normal adjacent tissues. We used miRTrail and protein-protein interaction methods to explore the related pathways and networks of deregulated microRNA and mRNA. By combining the results of pathways and networks, we found that the deregulated microRNA and their deregulated target mRNA are enriched in the following pathways: DNA replication, cell cycle, ECM-receptor interaction, focal adhesion, mismatch repair, and pathways in cancer. The results showed that many deregulated microRNAs and mRNAs may play a vital role in the pathogenesis of ESCC, and the systems biology approach is very helpful to explore molecular mechanism of ESCC.
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Identification of the protopanaxatriol synthase gene CYP6H for ginsenoside biosynthesis in Panax quinquefolius.
Funct. Integr. Genomics
PUBLISHED: 06-10-2014
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Panax quinquefolius is one of perennial herbs and well known for its outstanding pharmacological activity. Ginsenosides are thought to be the main active ingredients in P. quinquefolius and exist in many kinds of plant genus Panax (ginseng). Protopanaxatriol synthase, which is considered cytochrome P450 (CYP450) in ginsenoside biosynthesis pathway can convert protopanaxadiol into protopanaxatriol. However, the protopanaxatriol synthase gene in P. quinquefolius has not been identified. Here, we cloned and identified a protopanaxatriol synthase gene from P. quinquefolius (CYP6H, GenBank accession no. KC190491) at the first time, reverse transcription-PCR (RT-PCR) analysis showed no obvious transcription change of CYP6H in methyl jasmonate (MeJA)-induced hairy roots. Ectopic expression of CYP6H in Saccharomyces cerevisiae resulted in the production of protopanaxatriol with added exogenous protopanaxadiol and confirmed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC/APCIMS). Moreover, high-performance liquid chromatography (HPLC) analysis shows that RNA interferences of CYP6H in transgenic hairy roots could increase the accumulation of protopanaxadiol-type ginsenosides and decrease the accumulation of protopanaxatriol-type ginsenosides, whereas the effect of overexpression CYP6H in transgenic hairy roots was contrary. Our study indicated that CYP6H is a gene encoding protopanaxadiol 6-hydroxylase which could convert protopanaxadiol into protopanaxatriol in P. quinquefolius ginsenoside biosynthesis, we also have confirmed the function of CYP6H on effect accumulation of ginsenosides.
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MicroRNA-23a mediates mitochondrial compromise in estrogen deficiency-induced concentric remodeling via targeting PGC-1?.
J. Mol. Cell. Cardiol.
PUBLISHED: 05-28-2014
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It is well known that menopause could worsen age-related ventricular concentric remodeling following estrogen (E2) deficiency. However the underlying mechanisms of such phenomena are not fully understood. Mitochondria, as the 'cellular power station' of hearts, play an important role in maintaining normal cardiac function and structure. Therefore, the present study aims to investigate whether mitochondrial compromise is responsible for E2 deficiency associated concentric remodeling and, if so, what is its underlying molecular mechanism. We found evident concentric remodeling pattern in both postmenopausal and ovariectomized (OVX) mice, which could be attenuated by E2 replacement. Further study showed mitochondrial structural damages and respiratory function impairment in myocardium of both postmenopausal and OVX mice and E2 supplement reversed mitochondrial dysfunction in OVX mice, suggesting that E2 deficiency could induce mitochondrial compromise in the heart. Then, peroxisome proliferator-activated receptor-? co-activator 1-? (PGC-1?), a key mitochondrial function and biology regulator, was found significantly reduced in both postmenopausal and OVX mice. The reduction of PGC-1? protein level in OVX mice could be rescued by E2 delivery, indicating that E2 could positively regulate PGC-1? expression. Next, we found that microRNA-23a (miR-23a) could be negatively regulated by E2 in both myocardium and cultured cardiomyocytes. Moreover, miR-23a could directly downregulate PGC-1? expression in cardiomyocytes via binding to its 3'UTR which implied that miR-23a could be critical for the downregulation of PGC-1? under E2 deficiency. Overexpression of miR-23a was also found to damage mitochondria in cultured cardiomyocytes, ascribed to PGC-1? downregulation. Taken together, E2 deficiency may cause mitochondrial compromise through miR-23a-mediated PGC-1? downregulation, which may subsequently lead to the menopause-associated concentric remodeling.
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Hepatitis A virus and the origins of picornaviruses.
Nature
PUBLISHED: 05-12-2014
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Hepatitis A virus (HAV) remains enigmatic, despite 1.4 million cases worldwide annually. It differs radically from other picornaviruses, existing in an enveloped form and being unusually stable, both genetically and physically, but has proved difficult to study. Here we report high-resolution X-ray structures for the mature virus and the empty particle. The structures of the two particles are indistinguishable, apart from some disorder on the inside of the empty particle. The full virus contains the small viral protein VP4, whereas the empty particle harbours only the uncleaved precursor, VP0. The smooth particle surface is devoid of depressions that might correspond to receptor-binding sites. Peptide scanning data extend the previously reported VP3 antigenic site, while structure-based predictions suggest further epitopes. HAV contains no pocket factor and can withstand remarkably high temperature and low pH, and empty particles are even more robust than full particles. The virus probably uncoats via a novel mechanism, being assembled differently to other picornaviruses. It utilizes a VP2 'domain swap' characteristic of insect picorna-like viruses, and structure-based phylogenetic analysis places HAV between typical picornaviruses and the insect viruses. The enigmatic properties of HAV may reflect its position as a link between 'modern' picornaviruses and the more 'primitive' precursor insect viruses; for instance, HAV retains the ability to move from cell-to-cell by transcytosis.
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Small dedifferentiated cardiomyocytes bordering on microdomains of fibrosis: evidence for reverse remodeling with assisted recovery.
J. Cardiovasc. Pharmacol.
PUBLISHED: 05-03-2014
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With the perspective of functional myocardial regeneration, we investigated small cardiomyocytes bordering on microdomains of fibrosis, where they are dedifferentiated re-expressing fetal genes, and determined: (1) whether they are atrophied segments of the myofiber syncytium, (2) their redox state, (3) their anatomic relationship to activated myofibroblasts (myoFb), given their putative regulatory role in myocyte dedifferentiation and redifferentiation, (4) the relevance of proteolytic ligases of the ubiquitin-proteasome system as a mechanistic link to their size, and (5) whether they could be rescued from their dedifferentiated phenotype. Chronic aldosterone/salt treatment (ALDOST) was invoked, where hypertensive heart disease with attendant myocardial fibrosis creates the fibrillar collagen substrate for myocyte sequestration, with propensity for disuse atrophy, activated myoFb, and oxidative stress. To address phenotype rescue, 4 weeks of ALDOST was terminated followed by 4 weeks of neurohormonal withdrawal combined with a regimen of exogenous antioxidants, ZnSO4, and nebivolol (assisted recovery). Compared with controls, at 4 weeks of ALDOST, we found small myocytes to be: (1) sequestered by collagen fibrils emanating from microdomains of fibrosis and representing atrophic segments of the myofiber syncytia, (2) dedifferentiated re-expressing fetal genes (?-myosin heavy chain and atrial natriuretic peptide), (3) proximal to activated myoFb expressing ?-smooth muscle actin microfilaments and angiotensin-converting enzyme, (4) expressing reactive oxygen species and nitric oxide with increased tissue 8-isoprostane, coupled to ventricular diastolic and systolic dysfunction, and (5) associated with upregulated redox-sensitive proteolytic ligases MuRF1 and atrogin-1. In a separate study, we did not find evidence of myocyte replication (BrdU labeling) or expression of stem cell antigen (c-Kit) at weeks 1-4 ALDOST. Assisted recovery caused complete disappearance of myoFb from sites of fibrosis with redifferentiation of these myocytes, loss of oxidative stress, and ubiquitin-proteasome system activation, with restoration of nitric oxide and improved ventricular function. Thus, small dedifferentiated myocytes bordering on microdomains of fibrosis can re-differentiate and represent a potential source of autologous cells for functional myocardial regeneration.
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The isolation and characterization of dammarenediol synthase gene from Panax quinquefolius and its heterologous co-expression with cytochrome P450 gene PqD12H in yeast.
Funct. Integr. Genomics
PUBLISHED: 04-14-2014
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Panax quinquefolius is one of perennial herbs and well known for its outstanding pharmacological activity. Ginsenosides are thought to be the main active ingredients in Panax quinquefolius and exist in many kinds of plant genus Panax (ginseng). Dammarenediol synthase, which is considered as a key enzyme in ginsenoside biosynthesis pathway can convert 2, 3-oxidosqualene into dammarenediol-II. However, the dammarenediol synthase gene in Panax quinquefolius has not been identified. Here, we cloned and identified a dammarenediol synthase gene from Panax quinquefolius (PqDS, GenBank accession No. KC316048) at the first time, and reverse transcription-PCR (RT-PCR) analysis also showed an obvious transcription increase of PqDS in the methyl jasmonate (MeJA)-induced hairy roots. Ectopic expression of PqDS in yeast resulted in the production of dammarenediol-II was confirmed by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry (LC/APCIMS). Moreover, overexpression of PqDS in transgenic hairy roots could increase the transcription of gene PqDS and another P450 gene PqD12H (encoding protopanaxadiol synthase in Panax quinquefolius), the accumulation of ginsenosides also increased at the same time. In addition, both PqDS and PqD12H gene co-expressed in recombinant yeast result in the production of protopanaxadiol was detected by LC/APCIMS; this result also provides a new strategy for the abundant production of protopanaxadiol in vitro.
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Chimaphilin induces apoptosis in human breast cancer MCF-7 cells through a ROS-mediated mitochondrial pathway.
Food Chem. Toxicol.
PUBLISHED: 03-21-2014
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Chimaphilin, 2,7-dimethyl-1,4-naphthoquinone, is extracted from pyrola [Passiflora incarnata Fisch.]. In this study, the anticancer activity and underlying mechanisms of chimaphilin toward human breast cancer MCF-7 cells are firstly investigated. Chimaphilin could inhibit the viability of MCF-7 cells in a concentration-dependent manner, and the IC50 value was 43.30?M for 24h. Chimaphilin markedly induced apoptosis through the investigation of characteristic apoptotic morphological changes, nuclear DNA fragmentation, annexin V-FITC/propidium iodide (PI) double staining. Flow cytometry assay revealed that chimaphilin triggered a significant generation of ROS and disruption of mitochondrial membrane potential. Additionally, western blotting assay showed that chimaphilin suppressed Bcl-2 level and enhanced Bad level, then activated caspase-9 and caspase-3, and further activated the poly ADP-ribose polymerase (PARP), finally induced cell apoptosis involving the mitochondrial pathway. Furthermore, free radical scavengers N-acetyl-L-cysteine (NAC) pretreatment test testified that chimaphilin could increase the generation of ROS, then induce cell apoptosis. In general, the present results demonstrated that chimaphilin induced apoptosis in human breast cancer MCF-7 cells via a ROS-mediated mitochondrial pathway.
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Data mining and bioinformatics of the expression data of esophageal squamous cell carcinoma.
Cell Biochem. Biophys.
PUBLISHED: 03-06-2014
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The aim is to explore the molecular regulation mechanism of the pathogenesis of the esophageal squamous cell carcinoma. The expression data of esophageal squamous cell carcinoma were obtained from the GEO database. The differential expression genes were identified by the BRB-array tools and the pathway was analyzed by DAVID online tools. The class comparison analysis showed that there were 376 differential expression genes. These genes involved in many tumor-related pathways. What is more, these pathways had common genes. As a conclusion, it was helpful to comprehensively understand the pathogenesis of esophageal squamous carcinoma using data mining and bioinformatics analysis of esophageal squamous cell carcinoma. It would offer new ideas for target therapy of the esophageal squamous cell carcinoma.
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Pharmacophore-based virtual screening and experimental validation of novel inhibitors against cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphosphatase.
J Chem Inf Model
PUBLISHED: 02-21-2014
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Cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphoshatase (cy-FBP/SBPase) is a potential enzymatic target for screening of novel inhibitors that can combat harmful algal blooms. In the present study, we targeted the substrate binding pocket of cy-FBP/SBPase. A series of novel hit compounds from the SPECs database were selected by using a pharmacophore-based virtual screening strategy. Most of the compounds tested exhibited moderate inhibitory activities (IC50 = 20.7-176.9 ?M) against cy-FBP/SBPase. Compound 2 and its analogues 10 and 11 exhibited strong inhibitory activities, with IC50 values of 20.7, 13.4, and 19.0 ?M against cy-FBP/SBPase in vitro and EC50 values of 12.3, 10.9, and 2.9 ppm against cyanobacteria Synechocystis PCC6803 in vivo, respectively. The compound 10 was selected in order to perform a refined docking study to investigate the rational binding mode of inhibitors with cy-FBP/SBPase. Furthermore, possible interactions of the residues with inhibitors were examined by site-directed mutagenesis, enzymatic assays, and fluorescence spectral analyses. The results provide insight into the binding mode between the inhibitors and the substrate binding pocket. The observed theoretical and experimental results are in concert, indicating that the modeling strategies and screening methods employed are appropriate to search for novel lead compounds having both structural diversity and high inhibitory activity against cy-FBP/SBPase.
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Vascular endothelial growth factor-C: its unrevealed role in fibrogenesis.
Am. J. Physiol. Heart Circ. Physiol.
PUBLISHED: 01-24-2014
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Vascular endothelial growth factor (VEGF)-C is a key mediator of lymphangiogenesis. Our recent study shows that VEGF-C/VEGF receptors (VEGFR)-3 are significantly increased in the infarcted rat myocardium, where VEGFR-3 is expressed not only in lymph ducts but also in myofibroblasts, indicating that VEGF-C has an unrevealed role in fibrogenesis during cardiac repair. The current study is to explore the regulation and molecular mechanisms of VEGF-C in fibrogenesis. The potential regulation of VEGF-C on myofibroblast differentiation/growth/migration, collagen degradation/synthesis, and transforming growth factor (TGF)-? and ERK pathways was detected in cultured cardiac myofibroblasts. Our results showed that VEGF-C significantly increased myofibroblast proliferation, migration, and type I/III collagen production. Matrix metalloproteinase (MMP)-2 and -9 were significantly elevated in the medium of VEGF-C-treated cells, coincident with increased tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. Furthermore, VEGF-C activated the TGF-?1 pathway and ERK phosphorylation, which was significantly suppressed by TGF-? or ERK blockade. This is the first study indicating that in addition to lymphangiogenesis, VEGF-C is also involved in fibrogenesis through stimulation of myofibroblast proliferation, migration, and collagen synthesis, via activation of the TGF-?1 and ERK pathways.
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Autocrine and paracrine function of Angiotensin 1-7 in tissue repair during hypertension.
Am. J. Hypertens.
PUBLISHED: 01-15-2014
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Angiotensin-converting enzyme 2 (ACE2) cleaves angiotensin (Ang) II to generate Ang1-7, which mediates cellular actions through Mas receptors (MasR). Hypertension is accompanied by high or low circulating AngII levels and cardiac/renal injury. The purpose of this study is to explore (i) whether circulating AngII affects ACE2/MasR expressions in the hypertensive heart and kidney; and (ii) whether Ang1-7 regulates cardiac repair/remodeling responses through MasR during hypertension.
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Self-assembled micelles based on pH-sensitive PAE-g-MPEG-cholesterol block copolymer for anticancer drug delivery.
Int J Nanomedicine
PUBLISHED: 01-01-2014
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A novel amphiphilic triblock pH-sensitive poly(?-amino ester)-g-poly(ethylene glycol) methyl ether-cholesterol (PAE-g-MPEG-Chol) was designed and synthesized via the Michael-type step polymerization and esterification condensation method. The synthesized copolymer was determined with proton nuclear magnetic resonance and gel permeation chromatography. The grafting percentages of MPEG and cholesterol were determined as 10.93% and 62.02%, calculated from the area of the characteristic peaks, respectively. The amphiphilic copolymer was confirmed to self-assemble into core/shell micelles in aqueous solution at low concentrations. The critical micelle concentrations were 6.92 and 15.14 mg/L at pH of 7.4 and 6.0, respectively, obviously influenced by the changes of pH values. The solubility of pH-responsive PAE segment could be transformed depending on the different values of pH because of protonation-deprotonation of the amino groups, resulting in pH sensitivity of the copolymer. The average particle size of micelles increased from 125 nm to 165 nm with the pH decreasing, and the zeta potential was also significantly changed. Doxorubicin (DOX) was entrapped into the polymeric micelles with a high drug loading level. The in vitro DOX release from the micelles was distinctly enhanced with the pH decreasing from 7.4 to 6.0. Toxicity testing proved that the DOX-loaded micelles exhibited high cytotoxicity in HepG2 cells, whereas the copolymer showed low toxicity. The results demonstrated how pH-sensitive PAE-g-MPEG-Chol micelles were proved to be a potential vector in hydrophobic drug delivery for tumor therapy.
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Early transcriptional responses of bovine chorioallantoic membrane explants to wild type, ?virB2 or ?btpB Brucella abortus infection.
PLoS ONE
PUBLISHED: 01-01-2014
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The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM) explants inoculated with wild type (strain 2308), ?virB2 or ?btpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05) were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ?virB2 or the ?btpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ?virB and ?btpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion.
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Establishment of Paclitaxel-resistant Breast Cancer Cell Line and Nude Mice Models, and Underlying Multidrug Resistance Mechanisms in Vitro and in Vivo.
Asian Pac. J. Cancer Prev.
PUBLISHED: 12-03-2013
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Background: Breast cancer is a common malignant tumor which affects health of women and multidrug resistance (MDR) is one of the main factors leading to failure of chemotherapy. This study was conducted to establish paclitaxel-resistant breast cancer cell line and nude mice models to explore underlying mechanisms of MDR. Methods: The breast cancer drug-sensitive cell line MCF-7 (MCF-7/S) was exposed in stepwise escalating paclitaxel (TAX) to induce a resistant cell line MCF-7/TAX. Cell sensitivity to drugs and growth curves were measured by MTT assay. Changes of cell morphology and ultrastructure were examined by optical and electron microscopy. The cell cycle distribution was determined by flow cytometry. Furthermore, expression of proteins related to breast cancer occurrence and MDR was tested by immunocytochemistry. In Vivo, nude mice were injected with MCF-7/S and MCF-7/TAX cells and weights and tumor sizes were observed after paclitaxel treatment. In addition, proteins involved breast cancer and MDR were detected by immunohistochemistry. Results: Compared to MCF-7/S, MCF-7/TAX cells had a higher resistance to paclitaxel, cross-resistance and prolonged doubling time. Moreover, MCF-7/TAX showed obvious alterations of ultrastructure. Estrogen receptor (ER) expression was low in drug resistant cells and tumors while expression of human epidermal growth factor receptor 2 (HER2) and Ki-67 was up-regulated. P-glycoprotein (P-gp), lung resistance-related protein (LRP) and glutathione-S-transferase-? (GST-?) involved in the MDR phenotype of resistant cells and tumors were all overexpressed. Conclusion: The underlying MDR mechanism of breast cancer may involve increased expression of P-gp, LRP and GST-?.
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ANXA2 Regulates the Behavior of SGC-7901 Cells.
Asian Pac. J. Cancer Prev.
PUBLISHED: 12-03-2013
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ANXA2, a member of the annexin family, is overexpressed and plays important roles in tumor development. However, the significance of ANXA2 expression in gastric carcinoma has not been clarified.To elucidate its roles in growth of gastric cancer, ANXA2 expression in SGC-7901 cells was inhibited with a designated siRNA, then cell proliferation, cell cycling, apoptosis and motility were determined by MTT assay, flow cytometry, Hoechst 33342 staining and wound healing assay, respectively. To further assess the behavior of ANXA2 deleted SGC- 7901 cells, changes of microstructures were observed under fluorescence microscopy, laser scanning confocal microscopy and electron microscopy. We found that inhibition of ANXA2 expression caused cell proliferation to decrease significantly with G1 arrest, motility to be reduced with changes in pseudopodia/filopodia structure and F-actin and ?-tubulin expression, and apoptosis to be enhanced albeit without significance. At the same time, ANXA2 deletion resulted in fewer pseudopodia/filopodia, non-stained areas were increased, contact inhibition among cells reappeared, and expression of F-actin and ?-tubulin was decreased, with induction of polymerized disassembled forms. Taken together, these data suggest that ANXA2 overexpression is important to maintain the malignancy of cancer cells, and this member of the annexin family has potential to be considered as a target for the gene therapy of gastric carcinoma.
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Structural and biochemical characterization of fructose-1,6/sedoheptulose-1,7-bisphosphatase from the cyanobacterium Synechocystis strain 6803.
FEBS J.
PUBLISHED: 10-22-2013
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Cyanobacterial fructose-1,6/sedoheptulose-1,7-bisphosphatase (cy-FBP/SBPase) plays a vital role in gluconeogenesis and in the photosynthetic carbon reduction pathway, and is thus a potential enzymatic target for inhibition of harmful cyanobacterial blooms. Here, we describe the crystal structure of cy-FBP/SBPase in complex with AMP and fructose-1,6-bisphosphate (FBP). The allosteric inhibitor AMP and the substrate FBP exhibit an unusual binding mode when in complex with cy-FBP/SBPase. Binding mode analysis suggested that AMP bound to the allosteric sites near the interface across the up/down subunit pairs C1C4 and C2C3 in the center of the tetramer, while FBP binds opposite to the interface between the horizontal subunit pairs C1C2 or C3C4. We identified a series of residues important for FBP and AMP binding, and suggest formation of a disulfide linkage between Cys75 and Cys99. Further analysis indicates that cy-FBP/SBPase may be regulated through ligand binding and alteration of the structure of the enzyme complex. The interactions between ligands and cy-FBP/SBPase are different from those of ligand-bound structures of other FBPase family members, and thus provide new insight into the molecular mechanisms of structure and catalysis of cy-FBP/SBPase. Our studies provide insight into the evolution of this enzyme family, and may help in the design of inhibitors aimed at preventing toxic cyanobacterial blooms.
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Dissipative particle dynamics studies of doxorubicin-loaded micelles assembled from four-arm star triblock polymers 4AS-PCL-b-PDEAEMA-b-PPEGMA and their pH-release mechanism.
J Phys Chem B
PUBLISHED: 10-17-2013
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Dissipative particle dynamics (DPD) simulation was applied to investigate the microstructures of the micelles self-assembled from pH-sensitive four-arm star triblock poly(?-caprolactone)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (4AS-PCL-b-PDEAEMA-b-PPEGMA). In the optimized system, the micelles have a core-mesosphere-shell three-layer structure. The drug-loading process and its distribution at different formulations in the micelles were studied. The results show that DOX molecules distributed in the core and the interface between the core and the mesosphere, suggesting the potential encapsulation capacity of DOX molecules. More drugs were loaded in the micelles with the increase in DOX, and the size of micelles became larger. However, some openings start to generate on the PEG shell when the DOX reaches a certain concentration. By changing the pH values of the system, different morphologies of the micelles were acquired after the pH-sensitive blocks PDEAEMA were protonated, the mechanism of which was also analyzed through correlating functions. The results indicated that the sudden increase in solubility parameter of the pH-sensitive blocks and the swelling of the micelles were the key factors on the change of morphologies. Furthermore, with the decrease in pH value, the number and size of the cracks on the surface of the micelles were larger, which may have a direct effect on the drug release. In conclusion, 4AS-PCL-b-PDEAEMA-b-PPEGMA has great promising applications in delivering hydrophobic anticancer drugs for improved cancer therapy.
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Prognostic Value of Treadmill Stress Echocardiography at Extremes of Exercise Performance: Submaximal <85% Maximum Predicted Heart Rate versus High Exercise Capacity ?10 Metabolic Equivalents.
Echocardiography
PUBLISHED: 10-15-2013
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Submaximal stress testing or achieving <85% maximum predicted heart rate (MPHR) may lead to nondiagnostic results and indeterminate outcomes. High exercise capacity (?10 metabolic equivalents, METS) is a predictor of favorable prognosis. The purpose of this study was to evaluate the prognostic value of submaximal or high exercise capacity stress echocardiography.
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Atrophic cardiomyocyte signaling in hypertensive heart disease.
J. Cardiovasc. Pharmacol.
PUBLISHED: 10-03-2013
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: Cardinal pathological features of hypertensive heart disease (HHD) include not only hypertrophied cardiomyocytes and foci of scattered microscopic scarring, a footprint of prior necrosis, but also small myocytes ensnared by fibrillar collagen where disuse atrophy with protein degradation would be predicted. Whether atrophic signaling is concordant with the appearance of HHD and involves oxidative and endoplasmic reticulum (ER) stress remains unexplored. Herein, we examine these possibilities focusing on the left ventricle and cardiomyocytes harvested from hypertensive rats receiving 4 weeks aldosterone/salt treatment (ALDOST) alone or together with ZnSO4, a nonvasoactive antioxidant, with the potential to attenuate atrophy and optimize hypertrophy. Compared with untreated age-/sex-/strain-matched controls, ALDOST was accompanied by (1) left ventricle hypertrophy with preserved systolic function; (2) concordant cardiomyocyte atrophy (<1000 ?m) found at sites bordering on fibrosis where they were reexpressing ?-myosin heavy chain; and (3) upregulation of ubiquitin ligases, muscle RING-finger protein-1 and atrogin-1, and elevated 8-isoprostane and unfolded protein ER response with messenger RNA upregulation of stress markers. ZnSO4 cotreatment reduced lipid peroxidation, fibrosis, and the number of atrophic myocytes, together with a further increase in cell area and width of atrophied and hypertrophied myocytes, and improved systolic function but did not attenuate elevated blood pressure. We conclude that atrophic signaling, concordant with hypertrophy, occurs in the presence of a reparative fibrosis and induction of oxidative and ER stress at sites of scarring where myocytes are atrophied. ZnSO4 cotreatment in HHD with ALDOST attenuates the number of atrophic myocytes, optimizes size of atrophied and hypertrophied myocytes, and improves systolic function.
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[Metastatic characteristics of lymph node in supraclavicular zone and radiotherapy target volume for limited-stage small cell lung cancer].
Zhonghua Yi Xue Za Zhi
PUBLISHED: 09-14-2013
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To explore the reasonable radiotherapy range by analyzing the characteristics of supraclavicular lymph node metastasis in limited-stage small cell lung cancer (LS-SCLC).
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An open conformation determined by a structural switch for 2A protease from coxsackievirus A16.
Protein Cell
PUBLISHED: 08-21-2013
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Coxsackievirus A16 belongs to the family Picornaviridae, and is a major agent of hand-foot-and-mouth disease that infects mostly children, and to date no vaccines or antiviral therapies are available. 2A protease of enterovirus is a nonstructural protein and possesses both self-cleavage activity and the ability to cleave the eukaryotic translation initiation factor 4G. Here we present the crystal structure of coxsackievirus A16 2A protease, which interestingly forms hexamers in crystal as well as in solution. This structure shows an open conformation, with its active site accessible, ready for substrate binding and cleavage activity. In conjunction with a previously reported "closed" state structure of human rhinovirus 2, we were able to develop a detailed hypothesis for the conformational conversion triggered by two "switcher" residues Glu88 and Tyr89 located within the bll2-cII loop. Substrate recognition assays revealed that amino acid residues P1, P2 and P4 are essential for substrate specificity, which was verified by our substrate binding model. In addition, we compared the in vitro cleavage efficiency of 2A proteases from coxsackievirus A16 and enterovirus 71 upon the same substrates by fluorescence resonance energy transfer (FRET), and observed higher protease activity of enterovirus 71 compared to that of coxsackievirus A16. In conclusion, our study shows an open conformation of coxsackievirus A16 2A protease and the underlying mechanisms for conformational conversion and substrate specificity. These new insights should facilitate the future rational design of efficient 2A protease inhibitors.
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Enhancement of perovskite-based solar cells employing core-shell metal nanoparticles.
Nano Lett.
PUBLISHED: 08-19-2013
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Recently, inorganic and hybrid light absorbers such as quantum dots and organometal halide perovskites have been studied and applied in fabricating thin-film photovoltaic devices because of their low-cost and potential for high efficiency. Further boosting the performance of solution processed thin-film solar cells without detrimentally increasing the complexity of the device architecture is critically important for commercialization. Here, we demonstrate photocurrent and efficiency enhancement in meso-superstructured organometal halide perovskite solar cells incorporating core-shell Au@SiO2 nanoparticles (NPs) delivering a device efficiency of up to 11.4%. We attribute the origin of enhanced photocurrent to a previously unobserved and unexpected mechanism of reduced exciton binding energy with the incorporation of the metal nanoparticles, rather than enhanced light absorption. Our findings represent a new aspect and lever for the application of metal nanoparticles in photovoltaics and could lead to facile tuning of exciton binding energies in perovskite semiconductors.
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Nebivolol: a multifaceted antioxidant and cardioprotectant in hypertensive heart disease.
J. Cardiovasc. Pharmacol.
PUBLISHED: 08-08-2013
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Cardiomyocyte necrosis with attendant microscopic scarring is a pathological feature of human hypertensive heart disease (HHD). Understanding the pathophysiological origins of necrosis is integral to its prevention. In a rat model of HHD associated with aldosterone/salt treatment (ALDOST), myocyte necrosis is attributable to oxidative stress induced by cytosolic-free [Ca]i and mitochondrial [Ca]m overloading in which the rate of reactive oxygen species generation overwhelms their rate of detoxification by endogenous Zn-based antioxidant defenses. We hypothesized that nebivolol (Neb), unlike another ?1 adrenergic receptor antagonist atenolol (Aten), would have a multifaceted antioxidant potential based on its dual property as a ?3 receptor agonist, which activates endothelial nitric oxide synthase to stimulate nitric oxide (NO) generation. NO promotes the release of cytosolic Zn sequestered inactive by its binding protein, metallothionein. Given the reciprocal regulation between these cations, increased [Zn]i reduces Ca entry and attendant rise in [Ca]i and [Ca]m. Herein, we examined the antioxidant and cardioprotectant properties of Neb and Aten in rats receiving 4 weeks ALDOST. Compared with untreated age-/sex-matched controls, ALDOST alone or ALDOST with Aten, Neb cotreatment induced endothelial nitric oxide synthase activation, NO generation and a marked increase in [Zn]i with associated decline in [Ca]i and [Ca]m. Attendant antioxidant profile at subcellular and cellular levels included attenuation of mitochondrial H2O2 production and lipid peroxidation expressed as reduced 8-isoprostane concentrations in both mitochondria and cardiac tissue. Myocyte salvage was expressed as reduced microscopic scarring and tissue collagen volume fraction. Neb is a multifaceted antioxidant with unique properties as cardioprotectant in HHD.
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Structure-based design and synthesis of novel dual-target inhibitors against cyanobacterial fructose-1,6-bisphosphate aldolase and fructose-1,6-bisphosphatase.
J. Agric. Food Chem.
PUBLISHED: 07-26-2013
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Cyanobacteria class II fructose-1,6-bisphoshate aldolase (Cy-FBA-II) and cyanobacteria fructose-1,6-bisphosphatase (Cy-FBPase) are two neighboring key regulatory enzymes in the Calvin cycle of the cyanobacteria photosynthesis system. Each of them might be taken as a potential target for designing novel inhibitors to chemically control harmful algal blooms (HABs). In the present paper, a series of novel inhibitors were rationally designed, synthesized, and optimized based upon the structural and interactional information of both Cy-FBA-II and Cy-FBPase, and their inhibitory activities were examined in vitro and in vivo. The experimental results showed that compounds L19e-L19g exhibited moderate inhibitory activities (IC50 = 28.1-103.2 ?M) against both Cy-FBA-II and Cy-FBPase; compounds L19a-L19d, L19h, L20a-L20d exhibited high Cy-FBA-II inhibitory activities (IC50 = 2.3-16.9 ?M) and moderate Cy-FBPase inhibitory activities (IC50 = 31.5-141.2 ?M); however, compounds L20e-L20h could potently inhibit both Cy-FBA-II and Cy-FBPase with IC50 values less than 30 ?M, which demonstrated more or less dual-target inhibitors feature. Moreover, most of them exhibited potent algicide activity (EC50 = 0.8-22.3 ppm) against cyanobacteria Synechocystis sp. PCC 6803.
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HMDO-promoted peptide and protein synthesis in ionic liquids.
J. Org. Chem.
PUBLISHED: 07-05-2013
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Hexamethyldisiloxane (HMDO) has been developed to efficiently promote the metal-free direct coupling of an amino function of one cysteine-free peptide or protein and a C-terminal thioester of the second peptide in ionic liquids. The amide-coupling reaction proceeds smoothly under mild conditions to afford the corresponding products in good to excellent yields (63-94%). Peptide couplings were also achieved using in-situ-generated thioesters by the thioesterification of oxo esters.
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Correlation analysis of angiotensin-converting enzyme, angiotensinogen, and endothelial nitric oxide synthase gene polymorphisms and the progression of immunoglobulin A nephropathy/membranous nephropathy.
Hum. Pathol.
PUBLISHED: 06-15-2013
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The purpose of our study was to evaluate the correlation of polymorphisms in angiotensinogen (AGT), angiotensin-converting enzyme (ACE), and endothelial nitric oxide synthase (eNOS) genes and the development and prognostic implications for immunoglobulin A nephropathy (IgAN)/membranous nephropathy (MN). A polymerase chain reaction was performed for the AGT, ACE, and eNOS genes, followed by DNA sequencing and statistical analysis. There was a difference in ACE gene type II and type I between the IgAN and MN groups (P < .05) and in eNOS gene TT type and T type between the IgAN and MN groups (P < .05 and P < .01). In the IgAN group, significant differences were observed between ACE gene polymorphism and the age group of 20 years or less, male sex group, with/without hematuria, and high blood urea nitrogen (BUN; P < .05 or P < .01); between AGT gene polymorphism and with/without hematuria, high BUN, and pathologic classification (P < .05 or P < .01); and between eNOS gene polymorphism and high BUN and pathologic classification (P < .05 or P < .01). However, in the MN group, significant differences were observed between ACE gene polymorphism and the degree of proteinuria and high BUN (P < .001 and P < .05), between AGT gene polymorphism and with/without hematuria (P < .05), and between eNOS gene polymorphism and the degree of proteinuria and high BUN (P < .05 and P < .01). The ACE, AGT, and eNOS genes were correlated with the development of renal function failure in IgAN, whereas the ACE and eNOS genes were associated with the degree of proteinuria and the development of renal function failure in MN.
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[Application of capillary zone electrophoresis in the interaction analysis of protein C with protein C activator from Agkistrodon acutus venom].
Se Pu
PUBLISHED: 05-15-2013
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A new capillary zone electrophoresis method (CZE) has been established for the interaction analysis of protein C (PC) with a protein C activator (PCA) from Agkistrodon acutus venom. The analysis was performed on an uncoated fused-silica capillary with 75 microm i.d. and a total length of 60.2 cm (50 cm to the detector) with a buffer solution of 50 mmol/L Tris-HCl (pH 7.4) and 198 nm of wavelength. The factors which influence the separation of the PCA, such as buffer solution and ion concentration, and the interaction between the PCA and PC incubated for different times at 37.5 degrees C were studied. The linear range was from 10 to 300 mg/L. The limit of detection was 3 mg/L (S/N = 3). The relative standard deviation (RSD) for the migration time of the PCA was 0.56%. The RSD for the peak area was 3.8% (n = 6). The equal volumes of the PCA (200 mg/L) and PC (60 mg/L) were incubated for five minutes, at which their binding rate reached the maximum. And no hydrolyzed peptide chain from PC was found in the electropherogram. The PCA from Agkistrodon acutus venom could activate PC directly through changing the space conformation of PC. The method is simple, and highly sensitive with high resolution, and will provide important theoretical basis for the rapid detection of venom proteins and their activities in the future.
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Quantitative proteomics reveals the temperature-dependent proteins encoded by a series of cluster genes in thermoanaerobacter tengcongensis.
Mol. Cell Proteomics
PUBLISHED: 05-12-2013
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Comprehensive and quantitative information of the thermophile proteome is an important source for understanding of the survival mechanism under high growth temperature. Thermoanaerobacter tengcongensis (T. tengcongensis), a typical anaerobic thermophilic eubacterium, was selected to quantitatively evaluate its protein abundance changes in response to four different temperatures. With optimized procedures of isobaric tags for relative and absolute quantitation quantitative proteomics (iTRAQ), such as peptide fractionation with high-pH reverse phase (RP) high performance liquid chromatography (HPLC), tandem MS acquisition mode in LTQ Orbitrap Velos MS, and evaluation of the quantification algorithms, high quality of the quantitative information of the peptides identified were acquired. In total, 1589 unique proteins were identified and defined 251 as the temperature-dependent proteins. Analysis of genomic locations toward the correspondent genes of these temperature-dependent proteins revealed that more than 30% were contiguous units with relevant biological functions, which are likely to form the operon structures in T. tengcongensis. The RNA sequencing (RNA-seq) data further demonstrated that these cluster genes were cotranscribed, and their mRNA abundance changes responding to temperature exhibited the similar trends as the proteomic results, suggesting that the temperature-dependent proteins are highly associated with the correspondent transcription status. Hence, the operon regulation is likely an energy-efficient mode for T. tengcongensis survival. In addition, evaluation to the functions of differential proteomes indicated that the abundance of the proteins participating in sulfur-respiration on the plasma membrane was decreased as the temperature increased, whereas the glycolysis-related protein abundance was increased. The energy supply in T. tengcongensis at high temperature is, therefore, speculated not mainly through the respiration chain reactions.
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Angiotensin 1-7 Promotes Cardiac Angiogenesis Following Infarction.
Curr Vasc Pharmacol
PUBLISHED: 05-01-2013
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Angiogenesis is central to cardiac repair following myocardial infarction (MI). Cardiac angiotensin converting enzyme (ACE)2 is significantly increased postMI, which is coincident with activated angiogenesis. The function of ACE2 is to generate angiotensin (Ang)1-7, an active peptide with cellular actions mediated by Mas receptors. The current study is to determine whether Ang(1-7) is involved in cardiac angiogenesis and facilitates cardiac repair. In the first portion of the study, the temporal expressions of cardiac ACE2 and Mas receptors were detected in rats with MI. In the second portion, MI rats were treated with or without a Mas receptor antagonist, A779 (1mg/kg/day given by minipump) for 7 days. Vascular density and expression of angiogenic mediators in the infarcted myocardium and cardiac function were examined. Compared to controls, ACE2 and Mas receptor levels were significantly increased in the infarcted myocardium for 4 weeks of the observation period. Newly formed vessels were evident in the infarcted myocardium at day 7. Mas receptor blockade significantly reduced vascular density in the infarcted myocardium and impaired ventricular function. In addition, A779 treatment significantly suppressed the cardiac expressions of vascular endothelial growth factor (VEGF)-D and matrix metalloproteinase (MMP)-9 but not expression of other angiogenic mediators, including monocyte chemoattactant protein (MCP-1), VEGF-C, transforming growth factor (TGF)-?1 and integrin ?3. These observations indicate that Ang(1-7) promotes angiogenesis via stimulating the expression of cardiac VEGF-D and MMP-9, thus facilitating cardiac repair and ventricular function.
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Effect of body mass index on outcome in patients with suspected coronary artery disease referred for stress echocardiography.
Am. J. Cardiol.
PUBLISHED: 04-29-2013
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In patients with hypertension, heart failure, or coronary artery disease (CAD), obese patients have been shown to have a lower cardiac event rate compared with normal weight counterparts. This phenomenon has been termed the "obesity paradox." We sought to determine whether the obesity paradox exists in a cohort of patients referred for stress echocardiography. We evaluated 4,103 patients with suspected CAD (58 ± 13 years; 42% men) undergoing stress echocardiography (52% exercise and 47% dobutamine). Patients were divided into 3 groups on the basis of body mass index (BMI): 18.5 to 24.9, 25 to 29.9, and >30 kg/m(2). During the follow-up of 8.2 ± 3.6 years, there were 683 deaths (17%). Myocardial ischemia was present in 21% of the population. Myocardial ischemia was more prevalent in patients with a BMI of 18.5 to 24.9 kg/m(2) (26%) than those with a BMI of 25 to 29.9 kg/m(2) (21%) and >30 kg/m(2) (18%). Patients with a BMI of >30 kg/m(2) had the lowest death rate (1.2%/year) compared with those with a BMI of 25 to 29.9 kg/m(2) (1.75%/year) and 18.5 to 24.9 kg/m(2) (2.9%/year; p <0.001). After adjusting for significant clinical variables including exercise capacity, patients with higher BMI (>30 kg/m(2) and 25 to 29.9 kg/m(2)) had less risk of mortality compared with those with a BMI of 18.5 to 24.9 kg/m(2) (hazard ratio 0.58, 95% confidence interval 0.47 to 0.72, p <0.0001 and hazard ratio 0.69, 95% confidence interval 0.57 to 0.82, p <0.0001, respectively). In conclusion, higher survival rate in patients with higher BMI as previously described in patients with hypertension, heart failure, and CAD extends to patients with suspected CAD referred for stress echocardiography, independent of exercise capacity.
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Platelet-derived growth factor-D promotes fibrogenesis of cardiac fibroblasts.
Am. J. Physiol. Heart Circ. Physiol.
PUBLISHED: 04-12-2013
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Platelet-derived growth factor (PDGF)-D is a newly recognized member of the PDGF family with its role just now being understood. Our previous study shows that PDGF-D and its receptors (PDGFR-?) are significantly increased in the infarcted heart, where PDGFR-? is primarily expressed by fibroblasts, indicating the involvement of PDGF-D in the development of cardiac fibrosis. In continuing with these findings, the current study explored the molecular basis of PDGF-D on fibrogenesis. Rat cardiac fibroblasts were isolated and treated with PDGF-D (200 ng/ml medium). The potential regulation of PDGF-D on fibroblast growth, phenotype change, collagen turnover, and the transforming growth factor (TGF)-? pathway were explored. We found: 1) PDGF-D significantly elevated cardiac fibroblast proliferation, myofibroblast (myoFb) differentiation, and type I collagen secretion; 2) matrix metalloproteinase (MMP)-1, MMP-2, and MMP-9 protein levels were significantly elevated in PDGF-D-treated cells, which were coincident with increased expressions of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2; 3) PDGF-D significantly enhanced TGF-?1 synthesis, which was eliminated by TGF-? blockade with small-interfering RNA (siRNA); 4) the stimulatory role of PDGF-D on fibroblast proliferation and collagen synthesis was abolished by TGF-? blockade; and 5) TGF-? siRNA treatment significantly suppressed PDGF-D synthesis in fibroblasts. These observations indicate that PDGF-D promotes fibrogenesis through multiple mechanisms. Coelevations of TIMPs and MMPs counterbalance collagen degradation. The profibrogenic role of PDGF-D is mediated through activation of the TGF-?1 pathway. TGF-?1 exerts positive feedback on PDGF-D synthesis. These findings suggest the potential therapeutic effect of PDGFR blockade on interstitial fibrosis in the infarcted heart.
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Aspidin BB, a phloroglucinol derivative, induces cell cycle arrest and apoptosis in human ovarian HO-8910 cells.
Chem. Biol. Interact.
PUBLISHED: 04-06-2013
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Aspidin BB, an effective phloroglucinol derivative from Dryopteris fragrans (L.) Schott, has been previously reported to exert high biological activities. In this study, we analyzed the underlying mechanisms of aspidin BB on human ovarian cancer cell line, HO-8910. Aspidin BB significantly inhibited HO-8910 cell proliferation in a dose- and time-dependent manner. The IC50 values were 15.02, 25.79 and 68.81?M after 72, 48 and 24h treatment, respectively. Meanwhile, aspidin BB markedly induced apoptosis evidenced by characteristic apoptotic morphological changes, nuclear DNA fragmentation, annexin V-FITC/propidium iodide (PI) double staining and S peak. Western blot analysis showed that aspidin BB suppressed Bcl-2 expression and enhanced Bax expression to desintegrate the outer mitochondrial membrane, then caused cytochrome c release which led to the activation of effector caspase-3, and further cleaved the poly ADP-ribose polymerase (PARP) in the nucleus, finally induced cell apoptosis. Furthermore, aspidin BB provoked S phase arrest in HO-8910 cells with up-regulation of pRb, E2F1, CDK2, cyclin E and cyclin A proteins. Taken together, these findings support the conclusion that aspidin BB exhibits cytotoxicity towards human ovarian cancer HO-8910 cells through induction of apoptosis via mitochondrial pathway and arresting cell cycle progression in S phase.
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Biomimetic engineering of nanofibrous gelatin scaffolds with noncollagenous proteins for enhanced bone regeneration.
Tissue Eng Part A
PUBLISHED: 04-05-2013
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Biomimetic approaches are widely used in scaffolding designs to enhance tissue regeneration. In this study, we integrated noncollagenous proteins (NCPs) from bone extracellular matrix (ECM) with three-dimensional nanofibrous gelatin (NF-Gelatin) scaffolds to form an artificial matrix (NF-Gelatin-NCPs) mimicking both the nano-structured architecture and chemical composition of natural bone ECM. Through a chemical coupling process, the NCPs were evenly distributed over all the surfaces (inner and outer) of the NF-gelatin-NCPs. The in vitro study showed that the number of osteoblasts (MC3T3-E1) on the NF-Gelatin-NCPs was significantly higher than that on the NF-Gelatin after being cultured for 14 days. Both the alkaline phosphatase (ALP) activity and the expression of osteogenic genes (OPN, BSP, DMP1, CON, and Runx2) were significantly higher in the NF-Gelatin-NCPs than in the NF-Gelatin at 3 weeks. Von Kossa staining, backscattered scanning electron microscopy, and microcomputed tomography all revealed a higher amount of mineral deposition in the NF-Gelatin-NCPs than in the NF-Gelatin after in vitro culturing for 3 weeks. The in vivo calvarial defect study indicated that the NF-Gelatin-NCPs recruited more host cells to the defect and regenerated a higher amount of bone than the controls after implantation for 6 weeks. Immunohistochemical staining also showed high-level mineralization of the bone matrix in the NF-Gelatin-NCPs. Taken together, both the in vitro and in vivo results confirmed that the incorporation of NCPs onto the surfaces of the NF-Gelatin scaffold significantly enhanced osteogenesis and mineralization. Biomimetic engineering of the surfaces of the NF-Gelatin scaffold with NCPs, therefore, is a promising strategy to enhance bone regeneration.
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Imaging high-intensity focused ultrasound-induced tissue denaturation by multispectral photoacoustic method: an ex vivo study.
Appl Opt
PUBLISHED: 03-13-2013
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We present an ex vivo study for the first time, to the best of our knowledge, in multispectral photoacoustic imaging (PAI) of tissue denaturation induced by high-intensity focused ultrasound (HIFU) in this paper. Tissue of bovine muscle was thermally treated in a heated water bath and by HIFU, and then was imaged using a multispectral photoacoustic approach. Light at multiple optical wavelengths between 700 and 900 nm was delivered to the treated bovine muscle tissue to excite the photoacoustic signal. Apparent tissue denaturation has been observed in multispectral photoacoustic images after being treated in a water bath and by HIFU. It is interesting that the denaturation is more striking at shorter optical wavelength photoacoustic images than at longer optical wavelength photoacoustic images. Multispectral photoacoustic images of the tissue denaturation were further analyzed and the photoacoustic spectrums of the denaturized tissue were calculated in this paper. This study suggests that a multispectral PAI approach might be a promising tool to evaluate tissue denaturation induced by HIFU treatment.
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Design and syntheses of novel N-((4-oxo-4H-chromen-3-yl)methylene)benzohydrazide as inhibitors of cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphosphatase.
Bioorg. Med. Chem.
PUBLISHED: 03-01-2013
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Cyanobacterial fructose-1,6-/sedoheptulose-1,7-bisphoshatase (Cy-FBP/SBPase) is an important target enzyme for finding inhibitors to solve harmful algal bloom (HAB). In this study, as potential inhibitors of Cy-FBP/SBPase, a series of novel chromone-connecting benzohydrazone compounds (Novel N-((4-oxo-4H-chromen-3-yl)methylene)benzohydrazide) were designed and synthesized. Their inhibitory activities against Cy-FBP/SBPase were further examined in vitro. Some of these compounds, such as f6-f8, f11, f12 and f16, exhibit higher inhibitory activities (IC50=11.2-16.1 ?M), especially, the compound f7 was identified as the most potent inhibitor with IC50 value of 11.2 ?M. The probable binding-mode of compound f7 was further analyzed carefully by molecular docking methods. These results indicate that compound f7 could be used as a lead compound for further optimization and might have potential to be developed as a new algicide.
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Both the mevalonate and the non-mevalonate pathways are involved in ginsenoside biosynthesis.
Plant Cell Rep.
PUBLISHED: 02-28-2013
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When one of them was inhibited, the two pathways could compensate with each other to guarantee normal growth. Moreover, the sterol biosynthesis inhibitor miconazole could enhance ginsenoside level. Ginsenosides, a kind of triterpenoid saponins derived from isopentenyl pyrophosphate (IPP), represent the main pharmacologically active constituents of ginseng. In plants, two pathways contribute to IPP biosynthesis, namely, the mevalonate pathway in cytosol and the non-mevalonate pathway in plastids. This motivates biologists to clarify the roles of the two pathways in biosynthesis of IPP-derived compounds. Here, we demonstrated that both pathways are involved in ginsenoside biosynthesis, based on the analysis of the effects from suppressing either or both of the pathways on ginsenoside accumulation in Panax ginseng hairy roots with mevinolin and fosmidomycin as specific inhibitors for the mevalonate and the non-mevalonate pathways, respectively. Furthermore, the sterol biosynthesis inhibitor miconazole could enhance ginsenoside levels in the hairy roots. These results shed some light on the way toward better understanding of ginsenoside biosynthesis.
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Indole-based fluorescent sensors for selective detection of Hg2+.
J Fluoresc
PUBLISHED: 02-24-2013
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A series of indole-based fluorescent chemosensors 1-4 were prepared and investigated characteristick features with transition metal ions. Sensors 1 and 2 were selective for Hg(2+) ion among a series of metal ions in H2O-DMSO with association constants of 4.60×10(4) and 5.90×10(4)?M(-1) and detection limits of 140 and 101.6 ?M, respectively.
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Modification of oxidative stress on gene expression profiling in the rat infarcted heart.
Mol. Cell. Biochem.
PUBLISHED: 01-30-2013
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Cardiac oxidative stress is developed following myocardial infarction (MI) particularly in the first week of MI. The influence of reactive oxygen species (ROS) on gene expression profiling and molecular pathways in the infarcted myocardium remains uncertain and is explored in the present study. Rats with MI were treated with or without antioxidants for 1 week. Normal rats served as controls. Cardiac oxidative stress and gene profiling were investigated. Compared to normal hearts, malondialdehyde, a marker of oxidative stress, was significantly increased in the infarcted myocardium, which was significantly suppressed by antioxidants. Microarray assay showed that over a thousand genes were differentially expressed in the infarcted myocardium. Antioxidants significantly altered the expression of 159 genes compared to untreated MI rats. Ingenuity pathway analysis indicated that multiple pathway networks were affected by antioxidants, including those related to cell movement, growth/development, death, and inflammatory/fibrotic responses. IPA further identified that these changes were primarily related to NF?B, p38 MAPK, and ER?1/2 pathways. Hub genes were identified in the associated gene networks. This study reveals the gene networks associated with cardiac oxidative stress postMI. These observations indicate that ROS regulate various molecular and cellular actions related to cardiac repair/remodeling through multiple gene networks.
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Radiotherapy and chemotherapy are associated with improved outcomes over surgery and chemotherapy in the management of limited-stage small cell esophageal carcinoma.
Radiother Oncol
PUBLISHED: 01-20-2013
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This retrospective study evaluates the efficacy and safety of surgery and chemotherapy (S +CT) vs. radiotherapy and CT (RT+CT) in patients with limited stage small cell esophageal cancer (LS-SCEC).
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Identification of risk factors and characteristics of supraclavicular lymph node metastasis in patients with small cell lung cancer.
Med. Oncol.
PUBLISHED: 01-17-2013
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Thoracic radiotherapy provides a survival benefit in patients with limited-stage disease of small cell lung cancer (LS-SCLC), but inclusion and exclusion of prophylactic irradiation of the supraclavicular area are still controversial. This study analyses the risk factors and characteristics of lymph node metastases in the supraclavicular area of LS-SCLC patients, which could help in developing a better radiotherapy for the patients. A total of 239 patients with LS-SCLC were included in this retrospective analysis. Clinical characteristics and mediastinal lymph node metastasis were analyzed for association with SCM, and the SCM pattern was further analyzed based on the treatment planning CT scans. The SCM incidence was 34.7 % (83 of 239). The multivariate analysis showed that only the mediastinal level 2 (OR = 16.101, P = 0.000) and level 3 (OR = 5.597, P = 0.000) lymph node metastases were significantly associated with SCM. As the most frequently involved region, supraclavicular level I lymph node metastases were identified in 61 of 83 patients (73.5 %), followed by level III, level IV, level V, and level II lymph node metastases, accounting a total of 95.2 % for level I and/or III lymph node metastases, whereas the incidence of skip metastasis was only 4.8 %. SCLC patients with mediastinal level 2 and level 3 lymph node metastasis were at high risk of SCM. If prophylactic irradiation therapy is considered, the nodal clinical target volume of irradiation should include bilateral lower para-recurrent laryngeal neural region (level I) and the para-internal jugular venous region (level III).
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Innate immune recognition of flagellin limits systemic persistence of Brucella.
Cell. Microbiol.
PUBLISHED: 01-07-2013
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Brucella are facultative intracellular bacteria that cause chronic infections by limiting innate immune recognition. It is currently unknown whether Brucella?FliC flagellin, the monomeric subunit of flagellar filament, is sensed by the host during infection. Here, we used two mutants of Brucella melitensis, either lacking or overexpressing flagellin, to show that FliC hinders bacterial replication in vivo. The use of cells and mice genetically deficient for different components of inflammasomes suggested that FliC was a target of the cytosolic innate immune receptor NLRC4?in vivo but not in macrophages in vitro where the response to FliC was nevertheless dependent on the cytosolic adaptor ASC, therefore suggesting a new pathway of cytosolic flagellin sensing. However, our work also suggested that the lack of TLR5 activity of Brucella flagellin and the regulation of its synthesis and/or delivery into host cells are both part of the stealthy strategy of Brucella towards the innate immune system. Nevertheless, as a flagellin-deficient mutant of B.?melitensis wasfound to cause histologically demonstrable injuries in the spleen of infected mice, we suggested that recognition of FliC plays a role in the immunological stand-off between Brucella and its host, which is characterized by a persistent infection with limited inflammatory pathology.
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Picornavirus uncoating intermediate captured in atomic detail.
Nat Commun
PUBLISHED: 01-06-2013
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It remains largely mysterious how the genomes of non-enveloped eukaryotic viruses are transferred across a membrane into the host cell. Picornaviruses are simple models for such viruses, and initiate this uncoating process through particle expansion, which reveals channels through which internal capsid proteins and the viral genome presumably exit the particle, although this has not been clearly seen until now. Here we present the atomic structure of an uncoating intermediate for the major human picornavirus pathogen CAV16, which reveals VP1 partly extruded from the capsid, poised to embed in the host membrane. Together with previous low-resolution results, we are able to propose a detailed hypothesis for the ordered egress of the internal proteins, using two distinct sets of channels through the capsid, and suggest a structural link to the condensed RNA within the particle, which may be involved in triggering RNA release.
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Partial blocking of mouse DSPP processing by substitution of Gly(451)-Asp(452) bond suggests the presence of secondary cleavage site(s).
Connect. Tissue Res.
PUBLISHED: 12-16-2011
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Dentin sialophosphoprotein (DSPP) in the extracellular matrix of dentin is cleaved into dentin sialoprotein and dentin phosphoprotein, which originate from the NH(2)-terminal and COOH-terminal regions of DSPP, respectively. In the proteolytic processing of mouse DSPP, the peptide bond at Gly(451)-Asp(452) has been shown to be cleaved by bone morphogenetic protein 1 (BMP1)/Tolloid-like metalloproteinases. In this study, we generated transgenic mice expressing a mutant DSPP in which Asp(452) was substituted by Ala(452). Protein chemistry analyses of extracts from the long bone of these transgenic mice showed that the D452A substitution partially blocked DSPP processing in vivo. When the full-length form of mutant DSPP (designated "D452A-DSPP") isolated from the transgenic mice was treated with BMP1 in vitro, a portion of the D452A-DSPP was cleaved, suggesting the presence of secondary peptide bond(s) that can be broken by BMP1. To identify the potential secondary DSPP cleavage site(s), site-directed mutagenesis was performed to generate nine DNA constructs expressing DSPP-bearing substitutions at potential scission sites. These different types of mutant DSPP made in eukaryotic cell lines were treated with BMP1 and the digestion products were assessed by Western immunoblotting. All of the mutant DSPP molecular species were partially cleaved by BMP1, giving rise to a protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to that of normal dentin sialoprotein. Taken together, we concluded that in addition to the peptide bond Gly(451)-Asp(452), there must be a cryptic cleavage site or sites close to Asp(452) in the mouse DSPP that can be cleaved by BMP1.
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A simple and highly selective receptor for iodide in aqueous solution.
Analyst
PUBLISHED: 12-09-2011
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We synthesized a simple fluorescent receptor 3 bearing two boronic acid groups as recognition sites. The recognition behaviour of receptor 3 towards various anions was evaluated in THF/H(2)O (1:1, v/v) solution. Receptor 3 showed high selectivity for iodide among a series of anions. Fluorescence spectroscopy and computational calculations revealed that the electrostatic interaction played a crucial role in its high selectivity for iodide.
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Expression of dentin sialophosphoprotein in non-mineralized tissues.
J. Histochem. Cytochem.
PUBLISHED: 11-02-2011
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Dentin sialophosphoprotein (DSPP) and its cleaved products, dentin phosphoprotein (DPP) and dentin sialoprotein (DSP), play important roles in biomineralization. Believed to be tooth specific, the authors group revealed its expression in bone, and more recently, they and other groups also showed its expression in a few types of soft tissues. In this study, the authors systematically examined the expression of DSPP in a variety of non-mineralized tissues using reverse-transcription polymerase chain reaction (RT-PCR), real-time PCR, Western immunoblotting, and immunohistochemistry analyses in wild-type mice as well as ?-galactosidase assays in the Dspp lacZ knock-in mice. These approaches showed the presence of DSPP in the salivary glands, cartilage, liver, kidney, and brain and its absence in the heart and spleen. Real-time PCR showed that the expression levels of DSPP mRNA in salivary glands, cartilage, liver, and kidney were higher than in the bone. Interestingly, DSPP was observed in the pericytes of blood vessels in the dental pulp, which are believed to be able to differentiate into odontoblasts. On the basis of these observations, the authors conclude that DSPP and/or its cleaved products may fulfill important functions in certain non-mineralized tissues in addition to its role in biomineralization.
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Study on the interaction between cyanobacteria FBP/SBPase and metal ions.
Spectrochim Acta A Mol Biomol Spectrosc
PUBLISHED: 10-28-2011
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Fructose-1,6-/sedoheptulose-1,7-bisphosphatase (FBP/SBPase) is a potential important target enzyme for finding inhibitors to solve harmful algal bloom. In this paper, the interactions between FBP/SBPase and metal ions were studied by enzyme activity analysis, fluorescence and molecular modeling method. The enzyme activity analysis showed that FBP/SBPase can be activated by Mg2+ or Mn2+ but cannot be activated by Ca2+ or Zn2+. Spectroscopic analysis of emission quenching showed that quenching mechanism of FBP/SBPase with Mg2+ or Mn2+ was static quenching mechanism while that of Ca2+ or Zn2+ was dynamic quenching process. Hydrogen bonds and van der Waals interaction might be the predominant intermolecular forces in stabilizing FBP/SBPase-Mg2+ while hydrophobic forces were the predominant intermolecular forces in stabilizing FBP/SBPase-Mn2+. Microenvironment and conformation of FBP/SBPase were changed in binding reaction. The effect of metal ions and important amino acid residues on FBP/SBPase-metal ion complex was also discussed by molecular modeling study.
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First assessment of three-dimensional quantitative photoacoustic tomography for in vivo detection of osteoarthritis in the finger joints.
Med Phys
PUBLISHED: 08-24-2011
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The purpose of this pilot clinical study is to assess three-dimensional (3-D) quantitative photoacoustic tomography (qPAT) for in vivo detection of osteoarthritis (OA) in the finger joints.
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Tetraspanin CD151 maintains vascular stability by balancing the forces of cell adhesion and cytoskeletal tension.
Blood
PUBLISHED: 08-10-2011
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Tetraspanin CD151 is highly expressed in endothelial cells and regulates pathologic angiogenesis. However, the mechanism by which CD151 promotes vascular morphogenesis and whether CD151 engages other vascular functions are unclear. Here we report that CD151 is required for maintaining endothelial capillary-like structures formed in vitro and the integrity of endothelial cell-cell and cell-matrix contacts in vivo. In addition, vascular permeability is markedly enhanced in the absence of CD151. As a global regulator of endothelial cell-cell and cell-matrix adhesions, CD151 is needed for the optimal functions of various cell adhesion proteins. The loss of CD151 elevates actin cytoskeletal traction by up-regulating RhoA signaling and diminishes actin cortical meshwork by down-regulating Rac1 activity. The inhibition of RhoA or activation of cAMP signaling stabilizes CD151-silenced or -null endothelial structure in vascular morphogenesis. Together, our data demonstrate that CD151 maintains vascular stability by promoting endothelial cell adhesions, especially cell-cell adhesion, and confining cytoskeletal tension.
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Prognostic value of stress echocardiogram in patients with angiographically significant coronary artery disease.
Am. J. Cardiol.
PUBLISHED: 07-31-2011
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The purpose of this study was to evaluate the prognostic value of stress echocardiography in patients with angiographically significant coronary artery disease (CAD). Two hundred sixty patients (mean age 63 ± 10 years, 58% men) who underwent stress echocardiography (41% treadmill, 59% dobutamine) and coronary angiography within 3 months and without intervening coronary revascularization were evaluated. All patients had significant CAD as defined by coronary stenosis ?70% in major epicardial vessels or branches (45% had single-vessel disease, and 55% had multivessel disease). The left ventricle was divided into 16 segments and scored on a 5-point scale of wall motion. Patients with abnormal results on stress echocardiography were defined as those with stress-induced ischemia (increase in wall motion score of ?1 grade). Follow-up (3.1 ± 1.2 years) for nonfatal myocardial infarction (n = 23) and cardiac death (n = 6) was obtained. In patients with angiographically significant CAD, stress echocardiography effectively risk stratified normal (no ischemia, n = 91) in contrast to abnormal (ischemia, n = 169) groups for cardiac events (event rate 1.0%/year vs 4.9%/year, p = 0.01). Multivariate logistic regression analysis identified multivessel CAD (hazard ratio 2.53, 95% confidence interval 1.16 to 5.51, p = 0.02) and number of segments in which ischemia was present (hazard ratio 4.31, 95% confidence interval 1.29 to 14.38, p = 0.01) as predictors of cardiac events. A Cox proportional-hazards model for cardiac events showed small, significant incremental value of stress echocardiography over coronary angiography (p = 0.02) and the highest global chi-square value for both (p = 0.004). In conclusion, in patients with angiographically significant CAD, (1) normal results on stress echocardiography conferred a benign prognosis (event rate 1.0%/year), and (2) stress echocardiographic results (no ischemia vs ischemia) added incremental prognostic value to coronary angiographic results, and (3) stress echocardiography and coronary angiography together provided additive prognostic value, with the highest global chi-square value.
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Spironolactone prevents the inducibility of ventricular tachyarrhythmia in rats with aldosteronism.
J. Cardiovasc. Pharmacol.
PUBLISHED: 07-15-2011
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Myocardial fibrosis is considered a substrate for fatal ventricular arrhythmias (VAs). In rats receiving aldosterone/salt treatment (ALDOST) for ?4 weeks, foci of myocardial scarring that replace necrotic cardiomyocytes appear scattered throughout the right and left sides of the heart. We hypothesized that this adverse structural remodeling would promote the inducibility of VA, which could be prevented by cotreatment with spironolactone (A+Spiro), an aldosterone receptor antagonist and cardioprotective agent. In controls and each treatment group, we monitored: (1) electrocardiogram, ventricular electrogram, and arterial pressure before, during, and after bipolar electrical stimulation of the right ventricular outflow tract and apex at a strength 3× the pacing threshold, using both programmed stimulation with premature extra stimuli and 50-Hz burst pacing for 3 different durations; and (2) myocardial collagen volume fraction (CVF) as a marker of cardiac fibrosis. We found that VA (duration >200 ms accompanied by declining arterial pressure) was more inducible (P < 0.05) at 4 weeks (4 of 6) and with even greater frequency at 6 weeks (9 of 10) of ALDOST versus controls (0 of 6) and A+Spiro for 6 weeks (2 of 11). CVF (%) was proportionally increased (P < 0.05) at 4 and 6 weeks (8.4 ± 0.74 and 13.9 ± 1.9, respectively) of ALDOST compared with control group (2.6 ± 0.4) and A+Spiro group (5.3 ± 0.7). However, the effective refractory period was indistinguishable between groups, whereas the probability of VA was nonlinearly related to CVF. Thus, in rats with aldosteronism, in which a reduction in effective refractory period was not evident, the mechanism for VA susceptibility is presumably linked to a decrease in conduction velocity and/or increased dispersion of refractoriness, probably caused by consequential myocardial fibrosis.
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Influences of the thickness, misalignment, and dispersion of the Savart polariscope on the optical path difference and spectral resolution in the polarization interference imaging spectrometer.
Appl Opt
PUBLISHED: 07-12-2011
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After reviewing the spectrum-dividing principle of the Savart polariscope (SP) in the polarization interference imaging spectrometer (PIIS) that we developed, we analyze the influences of the thickness, misalignment, and dispersion of the SP on the optical path difference (OPD). The theoretical expression of the OPD for the misalignment of the SP optical axis is deduced, and the OPD is analyzed when the incident plane is parallel, at 45°, or orthogonal to the principal section of the left plate of the SP. The selective thickness of the single Savart plate is analyzed when it is placed at the ideal and misalignment positions. The influence of dispersion of the SP on the OPD is analyzed when the misalignment error is ±1. The relationships between the OPD and wavelength are simulated and validated with experiments. This work can provide theoretical and practical guidance for the design, calibration, modulation, innovation, experiment, and engineering of the PIIS.
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Different roles of membrane potentials in electrotaxis and chemotaxis of dictyostelium cells.
Eukaryotic Cell
PUBLISHED: 07-08-2011
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Many types of cells migrate directionally in direct current (DC) electric fields (EFs), a phenomenon termed galvanotaxis or electrotaxis. The directional sensing mechanisms responsible for this response to EFs, however, remain unknown. Exposing cells to an EF causes changes in plasma membrane potentials (V(m)). Exploiting the ability of Dictyostelium cells to tolerate drastic V(m) changes, we investigated the role of V(m) in electrotaxis and, in parallel, in chemotaxis. We used three independent factors to control V(m): extracellular pH, extracellular [K(+)], and electroporation. Changes in V(m) were monitored with microelectrode recording techniques. Depolarized V(m) was observed under acidic (pH 5.0) and alkaline (pH 9.0) conditions as well as under higher extracellular [K(+)] conditions. Electroporation permeabilized the cell membrane and significantly reduced the V(m), which gradually recovered over 40 min. We then recorded the electrotactic behaviors of Dictyostelium cells with a defined V(m) using these three techniques. The directionality (directedness of electrotaxis) was quantified and compared to that of chemotaxis (chemotactic index). We found that a reduced V(m) significantly impaired electrotaxis without significantly affecting random motility or chemotaxis. We conclude that extracellular pH, [K(+)], and electroporation all significantly affected electrotaxis, which appeared to be mediated by the changes in V(m). The initial directional sensing mechanisms for electrotaxis therefore differ from those of chemotaxis and may be mediated by changes in resting V(m).
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Airway epithelial wounds in rhesus monkey generate ionic currents that guide cell migration to promote healing.
J. Appl. Physiol.
PUBLISHED: 06-30-2011
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Damage to the respiratory epithelium is one of the most critical steps to many life-threatening diseases, such as acute respiratory distress syndrome and chronic obstructive pulmonary disease. The mechanisms underlying repair of the damaged epithelium have not yet been fully elucidated. Here we provide experimental evidence suggesting a novel mechanism for wound repair: endogenous electric currents. It is known that the airway epithelium maintains a voltage difference referred to as the transepithelial potential. Using a noninvasive vibrating probe, we demonstrate that wounds in the epithelium of trachea from rhesus monkeys generate significant outward electric currents. A small slit wound produced an outward current (1.59 ?A/cm(2)), which could be enhanced (nearly doubled) by the ion transport stimulator aminophylline. In addition, inhibiting cystic fibrosis transmembrane conductance regulator (CFTR) with CFTR(Inh)-172 significantly reduced wound currents (0.17 ?A/cm(2)), implicating an important role of ion transporters in wound induced electric potentials. Time-lapse video microscopy showed that applied electric fields (EFs) induced robust directional migration of primary tracheobronchial epithelial cells from rhesus monkeys, towards the cathode, with a threshold of <23 mV/mm. Reversal of the field polarity induced cell migration towards the new cathode. We further demonstrate that application of an EF promoted wound healing in a monolayer wound healing assay. Our results suggest that endogenous electric currents at sites of tracheal epithelial injury may direct cell migration, which could benefit restitution of damaged airway mucosa. Manipulation of ion transport may lead to novel therapeutic approaches to repair damaged respiratory epithelium.
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[Analysis of the clinical effects of anatomical plate and combined external fixator for the treatment of the elderly intertrochanteric hip fractures].
Zhongguo Gu Shang
PUBLISHED: 06-22-2011
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To summarize the therapeutic experience and analyse the clinical effects of anatomical plate and combined external fixator for the treatment of elderly intertrochanteric hip fractures.
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A set of novel microsatellite markers developed for the traditional Tibetan medicinal plant Halenia elliptica (Gentianaceae).
Am. J. Bot.
PUBLISHED: 06-10-2011
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Microsatellite primers were developed in the traditional Tibetan medicinal plant Halenia elliptica D. Don to investigate its genetic diversity and population genetic structure.
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Mitochondria-targeted cardioprotection in aldosteronism.
J. Cardiovasc. Pharmacol.
PUBLISHED: 06-02-2011
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Chronic aldosterone/salt treatment (ALDOST) is accompanied by an adverse structural remodeling of myocardium that includes multiple foci of microscopic scarring representing morphologic footprints of cardiomyocyte necrosis. Our previous studies suggested that signal-transducer-effector pathway leading to necrotic cell death during ALDOST includes intramitochondrial Ca overloading, together with an induction of oxidative stress and opening of the mitochondrial permeability transition pore (mPTP). To further validate this concept, we hypothesized that mitochondria-targeted interventions will prove to be cardioprotective. Accordingly, 8-week-old male Sprague-Dawley rats receiving 4 weeks ALDOST were cotreated with either quercetin, a flavonoid with mitochondrial antioxidant properties, or cyclosporine A (CsA), an mPTP inhibitor, and compared with ALDOST alone or untreated, age/sex-matched controls. We monitored mitochondrial free Ca and biomarkers of oxidative stress, including 8-isoprostane and H2O2 production; mPTP opening; total Ca in cardiac tissue; and collagen volume fraction to quantify replacement fibrosis, a biomarker of cardiomyocyte necrosis, and employed terminal deoxynucleotidyl transferase dUTP nick end labeling assay to address apoptosis in coronal sections of ventricular myocardium. Compared with controls, at 4 weeks ALDOST we found a marked increase in mitochondrial H2O2 production and 8-isoprostane levels, an increased propensity for mPTP opening, and greater concentrations of mitochondrial free [Ca]m and total tissue Ca, coupled with a 5-fold rise in collagen volume fraction without any terminal deoxynucleotidyl transferase dUTP nick end labeling-based evidence of cardiomyocyte apoptosis. Each of these pathophysiologic responses to ALDOST was prevented by quercetin or cyclosporine A cotreatment. Thus, mitochondria play a central role in initiating the cellular-subcellular mechanisms that lead to necrotic cell death and myocardial scarring. This destructive cycle can be interrupted and myocardium salvaged with its structure preserved by mitochondria-targeted cardioprotective strategies.
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[Effects of GM3 on proliferation, apoptosis and VEGF expression in human lung adenocarcinoma cell line A549 cells].
Zhonghua Zhong Liu Za Zhi
PUBLISHED: 05-18-2011
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To determine the effect of exogenous GM3 on proliferation, apoptosis and VEGF expression in human lung adenocarcinoma cell line A549 cells.
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Mitochondriocentric pathway to cardiomyocyte necrosis in aldosteronism: cardioprotective responses to carvedilol and nebivolol.
J. Cardiovasc. Pharmacol.
PUBLISHED: 05-12-2011
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Foci of fibrosis, footprints of cardiomyocyte necrosis, are scattered throughout the failing myocardium and are a major component to its pathologic remodeling. Understanding pathogenic mechanisms contributing to hormone-mediated necrosis is therefore fundamental to developing cardioprotective strategies. In this context, a mitochondriocentric signal-transducer-effector pathway to necrosis is emerging. Our first objective, using cardiomyocytes and subsarcolemmal mitochondria (SSM) harvested from rats receiving a 4-week aldosterone/salt treatment (ALDOST), was to identify the major components of this pathway. Second, to validate this pathway, we used mitochondria-targeted pharmaceutical interventions as cardioprotective strategies using 4-week cotreatment with either carvedilol (Carv) or nebivolol (Nebiv). Compared with controls, we found the 4-week ALDOST to be accompanied by elevated cardiomyocyte free [Ca(2+)]i and SSM free [Ca(2+)]m; increased H(2)O(2) production and 8-isoprostane in SSM, cardiac tissue, and plasma; and enhanced opening of mitochondrial permeability transition pore (mPTP) and myocardial scarring. Increments in the antioxidant capacity augmented by increased cytosolic free [Zn(2+)]i were overwhelmed. Cotreatment with either Carv or Nebiv attenuated [Ca(2+)]i and [Ca(2+)]m overloading, prevented oxidative stress, and reduced mPTP opening while augmenting [Zn(2+)]i and conferring cardioprotection. Thus, major components of the mitochondriocentric signal-transducer-effector pathway to cardiomyocyte necrosis seen with ALDOST include intracellular Ca overloading coupled to oxidative stress and mPTP opening. This subcellular pathway can be favorably regulated by Carv or Nebiv cotreatment to salvage cardiomyocytes and prevent fibrosis.
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Roles of DMP1 processing in osteogenesis, dentinogenesis and chondrogenesis.
Cells Tissues Organs (Print)
PUBLISHED: 05-09-2011
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Dentin matrix protein 1 (DMP1) is an acidic protein that plays critical roles in osteogenesis and dentinogenesis. Protein chemistry studies have demonstrated that DMP1 primarily exists as processed NH?? and COOH-terminal fragments in the extracellular matrix of bone and dentin. Our earlier work showed that the substitution of Asp²¹³ (a residue at a cleavage site) by Ala²¹³ blocks the processing of mouse DMP1 in vitro. Recently, we generated transgenic mice expressing this mutant DMP1 (designated D213A-DMP1). By crossbreeding these transgenic mice with Dmp1-knockout (Dmp1-KO) mice, we obtained mice expressing the D213A-DMP1 transgene in the Dmp1-null background (named Dmp1-KO/D213A-Tg mice). In this study, we analyzed the long bone, mandible, dentin, and cartilage of Dmp1-KO/D213A-Tg mice in comparison with wild-type, Dmp1-KO, and Dmp1-KO mice expressing the normal DMP1 transgene (Dmp1-KO/normal-Tg). Our results showed that D213A-DMP1 was barely cleaved in the dentin matrix of Dmp1-KO/D213A-Tg mice and the expression of D213A-DMP1 failed to rescue the developmental defects in Dmp1-null mice. Interestingly, enlarged growth plates and condylar cartilages were observed in Dmp1-KO/D213A-Tg mice, indicating a potential role of the full-length form of DMP1 in chondrogenesis.
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Mesoscopic simulations on the aggregation behavior of pH-responsive polymeric micelles for drug delivery.
J Colloid Interface Sci
PUBLISHED: 05-03-2011
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Computer simulations, dissipative particle dynamics (DPD) and mesoscopic dynamics (MesoDyn), are performed to study the aggregation behavior of pH-sensitive micelles self-assembled from amphiphilic polymer poly(methyl methacrylate-co-methacrylic acid)-b-poly(poly-(ethylene glycol) methyl ether monomethacrylate), P(MMA-co-MAA)-b-PPEGMA. Ibuprofen (IBU) is selected as the model drug. It can be seen from DPD simulations that P(MMA-co-MAA)-b-PPEGMA and IBU form spherical core-shell micelles at certain compositions, and IBU molecules distribute inside the core formed by hydrophobic MMA. The polymer molecules aggregate first, and then IBU diffuses into the aggregate, forming drug-loaded nanoparticles. With different compositions of polymer and IBU, aggregate morphologies in water are observed as sphere, column and lamella. From MesoDyn results, with less hydrophobic MMA beads, the polymer chains are more difficult to form ordered aggregates, and the order parameters get equilibrated in a longer time. The pH value also affects the aggregate process. At pH<5, the polymer could form traditional core-shell micelles. But at pH>5, the morphology of micelles is found to be anomalous and loose for releasing drug. MAA aggregates on the surface, instead of the inside. The simulation results are qualitatively consistent with the experimental results.
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Platelet-derived growth factor involvement in myocardial remodeling following infarction.
J. Mol. Cell. Cardiol.
PUBLISHED: 04-20-2011
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Cardiac remodeling occurs in the infarcted heart (MI). The underlying regulatory mechanisms are under investigation. Platelet-derived growth factor (PDGF) is a family of growth factors that stimulates cell growth, differentiation and migration. Herein, we sought to determine whether PDGF is involved in cardiac repair/remodeling following MI. The temporal and spatial expressions of PDGF isoforms (A, B, C and D) and PDGF receptor (PDGFR)-? and ? as well as cell types expressing PDGF were examined in the infarcted rat heart. Sham-operated rats served as controls. We found that the normal myocardium expressed all PDGF isoforms, and cell types expressing PDGF were primarily interstitial cells. Following MI, PDGF-A and D were significantly increased in the infarcted myocardium during 6 weeks of the observation period and cells expressing PDGF-A and D were primarily endothelial cells, macrophages and myofibroblasts (myoFb). PDGF-B and C expressions were, however, reduced in the infarcted heart. In the noninfarcted myocardium, PDGF-D expression was increased in the late stage of MI and cells expressing PDGF-D were predominantly fibroblasts. Both PDGFR-? and ? were significantly increased in the infarcted myocardium in the early and late stages of MI and in the noninfarcted myocardium in the late stage of MI. Enhanced PDGF-A, PDGF-D and PDGFR are coincident with angiogenesis, and inflammatory and fibrogenic responses in the infarcted myocardium, suggesting their regulation on cardiac repair. Elevated PDGF-D in the noninfarcted myocardium suggests its involvement in the development of interstitial fibrosis that appears in the late stage of MI.
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Prehension synergies during smooth changes of the external torque.
Exp Brain Res
PUBLISHED: 04-05-2011
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We studied characteristics of digit action and their co-variation patterns across trials (prehension synergies) during static holding of an object while the external torque could change slowly and smoothly. The subjects held in the air an instrumented handle with an attachment that allowed a smooth change in the external torque over about 12 s; the load was always kept constant. Series of trials were performed under three conditions: The torque could be zero throughout the trial, or it could change slowly requiring a smooth change of the effort from a non-zero pronation value to zero (PR-0) or from a non-zero supination value to zero (SU-0). The handle was kept vertical at all times. Indices of variance and co-variation of elemental variables (forces and moments of force produced by individual digits) stabilizing such performance variables as total normal force, total tangential force, and total moment of force were computed at two levels of an assumed control hierarchy. At the upper level, the task is shared between the thumb and virtual finger (an imagined digit with the mechanical action equal to that of the four fingers), while at the lower level, the action of the virtual finger is shared among the actual four fingers. We analyzed the total moment of force as the sum of the moments of force produced by the thumb and virtual finger and also as the sum of the moments of force produced by the normal forces and tangential forces. The results showed that the adjustments in the total moment of force were produced primarily with changes in the moment produced by the virtual finger and by changes in the moment produced by the normal forces. The normal force of the thumb at the final state (which was the same across conditions) was larger in the two conditions with changes in the external torque. The safety margin was significantly higher in the PR-0 condition, and it dropped with the decrease in the external torque. A co-contraction index was computed to reflect the moment of force production by the fingers acting against the total moment produced by the virtual finger. It was higher for the SU-0 condition. Most variance indices dropped with a decrease in the external torque. The co-variation indices, however, remained unchanged over the trial duration. They showed signs of a trade-off between the two levels of the assumed hierarchy: larger indices at the higher level corresponded to smaller indices at the lower level. This study and the previous one (Sun et al. in Exp Brain Res 209:571-585, 2011) document several previously unknown features of prehensile tasks. The results show that characteristics of digit action and interaction in such tasks depend not only on the magnitudes of external constraints but also on a variety of other factors including time changes in the constraints and their history.
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Speed-difficulty trade-off in speech: Chinese versus English.
Exp Brain Res
PUBLISHED: 03-26-2011
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This study continues the investigation of the previously described speed-difficulty trade-off in picture description tasks. In particular, we tested a hypothesis that the Mandarin Chinese and American English are similar in showing logarithmic dependences between speech time and index of difficulty (ID), while they differ significantly in the amount of time needed to describe simple pictures, this difference increases for more complex pictures, and it is associated with a proportional difference in the number of syllables used. Subjects (eight Chinese speakers and eight English speakers) were tested in pairs. One subject (the Speaker) described simple pictures, while the other subject (the Performer) tried to reproduce the pictures based on the verbal description as quickly as possible with a set of objects. The Chinese speakers initiated speech production significantly faster than the English speakers. Speech time scaled linearly with ln(ID) in all subjects, but the regression coefficient was significantly higher in the English speakers as compared with the Chinese speakers. The number of errors was somewhat lower in the Chinese participants (not significantly). The Chinese pairs also showed a shorter delay between the initiation of speech and initiation of action by the Performer, shorter movement time by the Performer, and shorter overall performance time. The number of syllables scaled with ID, and the Chinese speakers used significantly smaller numbers of syllables. Speech rate was comparable between the two groups, about 3 syllables/s; it dropped for more complex pictures (higher ID). When asked to reproduce the same pictures without speaking, movement time scaled linearly with ln(ID); the Chinese performers were slower than the English performers. We conclude that natural languages show a speed-difficulty trade-off similar to Fitts law; the trade-offs in movement and speech production are likely to originate at a cognitive level. The time advantage of the Chinese participants originates not from similarity of the simple pictures and Chinese written characters and not from more sloppy performance. It is linked to using fewer syllables to transmit the same information. We suggest that natural languages may differ by informational density defined as the amount of information transmitted by a given number of syllables.
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