Biomedical subjects
Publications and source records attributed to Yan Wang.
As one of the mechanisms for stable multiwavelength oscillation in a fiber Raman ring laser, an inhomogeneous loss induced by intraline four-wave mixing in a fiber Raman laser is physically explained and experimentally validated by comparison of laser peak gain and power gain as well as the gain spectra at several pump levels.
The present report describes the preparation and characterization of large-bore particle-entrapped monolithic precolumns, which are suitable for incorporation into a two-dimensional liquid chromatography (2D-LC) system for proteome analysis. The fritless precolumns with different inner diameter (i.d.) (320 and 530 microm) were rapidly and successfully prepared by entrapping octadecylsilica (ODS) particles (5 microm, 300 A) prepacked into fused silica capillaries with a sol-gel network, which was formed by hydrolysis and polycondensation of methyltriethoxysilane (MTES). By optimizing the composition of the sol solution, the resulting large-bore monolithic precolumns of 5 mm length allow a flow rate of 20 microL/min loading buffer at a reasonable low back pressure of 25 bar or less and are capable of withstanding up to 300 bar inlet pressure. Scanning electron micrograms of the precolumns profile showed that the evolving sol-gel network joined particles to each other and onto the column wall, and no cracking or shrinkage of the column bed was observed even in 530 microm-i.d. capillary. The performance of the particle-entrapped monolithic precolumns used for preconcentration and desalting of proteolytic digest was evaluated by on-line coupling the large-bore precolumns with a capillary reversed-phase liquid chromatographic (RPLC) column followed by UV detection. The laboratory-made monolithic precolumns with 320 and 530 microm i.d. were characterized by using BSA tryptic digest or peptide standards as the analytes with respect to sample loading capacity, linearity, recovery and reproducibility, etc. The results indicate that the large-bore and short precolumns (5 mm x 320 microm i.d. or 5 mm x 530 microm i.d.) allow sample fast loading at a flow rate of 30 or 60 microL/min. The precolumns also have a mass loading capacity for BSA peptides of about 70 microg and for standard peptides of about 80 microg. Good linear calibration curves (R2 > 0.99) were obtained and the limits of detection (signal-to-noise ratio, S/N = 3) were improved by more than 60-fold and were between 0.53 and 1.32 ng/microL even with a UV absorbance detector. The total recovery was found to be approximately 90-100% for BSA digest and standard peptides. The day-to-day relative standard deviation (RSD) values for recoveries of BSA peptides on a single precolumn ranged from 4.66 to 7.56% and 2.68 to 3.05% for precolumn back pressure, while the column-to-column RSD values were 3.51-6.13% and 1.22-1.26% for recoveries of BSA peptides and precolumn back pressure, respectively. With good precolumn reproducibility, no significant degradation or decrease in precolumn performance was showed even after approximately 150 preconcentration/desorption cycles. The precolumns also proved to be resistant to salt buffer with high concentration and low-pH mobile phase. The large-bore particle-entrapped monolithic precolumns will be further used in a high-throughput 2D-LC array system coupled with tandem matrix assisted laser desorption/ionization-time of flight-time of flight-mass spectrometry (MALDI-TOF-TOF-MS) detection for proteome analysis.
Cytochrome P450 arachidonic acid (AA) epoxygenase metabolites, the epoxyeicosatrienoic acids (EETs), dilate arteries via hyperpolarization of smooth muscle cells and also have nonvasodilatory effects within the vasculature. The present study investigated the angiogenic effects of endogenous and exogenous EETs and the relevant signaling mechanisms involved. Bovine aortic endothelial cells (BAECs) were incubated with synthetic EETs or infected with recombinant adeno-associated viruses (rAAVs) containing CYP2C11-NADPH-cytochrome P450 oxidoreductase (CYPOR), CYP2J2, or CYP102 F87V mutant to increase endogenous levels of EETs. The following endpoints were measured: BAEC proliferation, migration, capillary formation, and in vivo angiogenesis. The potential involvement of various signaling pathways was explored using selective inhibitors. The results showed that transfection with either rAAV-CYP2C11-CYPOR, rAAV-CYP2J2, or rAAV-CYP102 F87V, or incubation with EETs promoted BAEC proliferation, increased migration of BAECs as assessed by Transwell analysis and wound healing assays, and enhanced capillary tubule formation as determined by chicken embryo chorioallantoic membrane assays and tube formation tests on matrigel. The effects of EETs on proliferation, migration, and capillary tubule formation were attenuated by inhibitors of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 (PI3)-kinase/Akt pathways and partially attenuated by an endothelial nitric-oxide synthase (eNOS) inhibitor but not by a protein kinase C inhibitor. In a rat ischemic hind limb model, rAAV-mediated AA epoxygenase transfection induced angiogenesis. We conclude that AA epoxygenase metabolites can promote angiogenesis, which may provide protection to ischemic tissues. The results also suggest that the angiogenic effects of EETs involve the MAPK and PI3-kinase/Akt signaling pathways, and to some extent, the eNOS pathway.
The activation of glial cells has been thought to be a universal and important reaction to trauma and pathology in the mammalian central nervous system. The mechanism of glial activation is not completely clear to date, but numerous cytokines have been demonstrated to effectively influence the process in vitro and in vivo. Here we reported the axotomy-induced upregulation of interferon-gamma (IFN-gamma) receptor mRNA in the mouse hippocampus following transections of the entorhinal afferents. Northern blot analysis showed that the transcripts of IFN-gamma receptor were upregulated in a transient manner in the deafferented mouse hippocampus. In situ hybridization confirmed the temporal upregulation of IFN-gamma receptor mRNA specifically in the denervated areas of the mouse hippocampus, which showed that the expression of IFN-gamma receptor mRNA rose slightly at 2 days postlesion, increased remarkably at 3 days postlesion, nearly reached the maximum at 7 days postlesion, and almost returned to control levels at 15 days postlesion. Double labeling further proved that the upregulated IFN-gamma receptor mRNA was confined to reactive astrocytes. At 2 and 3 days postlesion, we also observed the expression of IFN-gamma mRNA by a small number of cells in the denervated areas. We noted that the upregulation of both IFN-gamma and its receptor expression coincided spatiotemporally with astroglial activation, suggesting the potential involvement of IFN-gamma and its receptor in the activation process of astrocytes in the hippocampus following entorhinal deafferentation.
Several new ethynyl- and ethenyl-4-phenylamino-3-quinolinecarbonitriles were synthesized and tested for Src inhibition. Derivatives bearing an ethenyl or ethynyl substituent at C-6 showed decreased Src inhibitory activity. Incorporation of an ethenylpyridine N-oxide group at C-7 provided 20b, a 0.6 nM inhibitor of Src enzymatic activity with excellent cellular potency.
Fragile X syndrome is a leading heritable cause of mental retardation that results from the loss of FMR1 gene function. A Drosophila model for Fragile X syndrome, based on the loss of dfmr1 activity, exhibits phenotypes that bear similarity to Fragile X-related symptoms. Herein, we demonstrate that treatment with metabotropic glutamate receptor (mGluR) antagonists or lithium can rescue courtship and mushroom body defects observed in these flies. Furthermore, we demonstrate that dfmr1 mutants display cognitive deficits in experience-dependent modification of courtship behavior, and treatment with mGluR antagonists or lithium restores these memory defects. These findings implicate enhanced mGluR signaling as the underlying cause of the cognitive, as well as some of the behavioral and neuronal, phenotypes observed in the Drosophila Fragile X model. They also raise the possibility that compounds having similar effects on metabotropic glutamate receptors may ameliorate cognitive and behavioral defects observed in Fragile X patients.
As a continuation of our SAR studies of dipeptidyl aspartyl-fmk as caspase inhibitors, we explored the replacement of the P2 alpha-amino acid by a peptidomimetic alpha-hydroxy acid. These alpha-carbamoyl-alkylcarbonyl-aspartyl fluoromethylketones were found to be potent caspase inhibitors, and the SAR of these compounds is similar to the corresponding dipeptidyl aspartyl-fmk. MX1153, (S)-3-methyl-2-(phenylcarbamoyl)butanoyl-Asp-fmk, is identified as a potent broad-spectrum caspase inhibitor, and is selective for caspases versus other proteases. MX1153 also has good activity in the cell apoptosis protection assays and is active in the mouse liver apoptosis model.
OBJECTIVE: To analyze the clinical diagnosis and treatment of hepatic hydatid disease and its epidemiological characteristics in Yili river valley. METHODS: Retrospective investigation was carried out on 2049 cases collected in 1993-2003. Clinical diagnosis was made by ways of intradermal test, serological test, ultrasound, X-ray, CT and/or MRI, majority of them received surgical operation. RESULTS: Among the 2049 cases, cystic hydatidosis occupied 96% (1965/2049), while 4% (84/2049) were alveolar hydatidosis. 99% (2034/2049) accepted surgery including hepatolobectomy, endocystomy and hydatidostomy in 302 cases (14.7%) without relapses. 754 cases (36.7%) received chemotherapy (praziquantel, albendazole) after surgical operation. The disease distributed in agri-pastoral areas along the valley. Local residents from different minorities had a close contact with dogs, 54% of the cases were females and 48% of the cases were in the group of 25-49 years old. The incidence tends to decline in the years. CONCLUSION: Hydatidosis is still an important health problem in the region. Further practices for improving treatment especially surgical intervention and for epidemiological investigation are needed.
We have developed a visualization methodology, called a "cluster overlap distribution map" (CODM), for comparing the clustering results of time series gene expression profiles generated under two different conditions. Although various clustering algorithms for gene expression data have been proposed, there are few effective methods to compare clustering results for different conditions. With CODM, the utilization of three-dimensional space and color allows intuitive visualization of changes in cluster set composition, changes in the expression patterns of genes between the two conditions, and relationship with other known gene information, such as transcription factors. We applied CODM to time series gene expression profiles obtained from rat four-vessel occlusion models combined with systemic hypotension and time-matched sham control animals (with sham operation), identifying distinct pattern alteration between the two. Comparisons of dynamic changes of time series gene expression levels under different conditions are important in various fields of gene expression profiling analysis, including toxicogenomics and pharmacogenomics. CODM will be valuable for various types of analyses within these fields, because it integrates and simultaneously visualizes various types of information across clustering results.
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The pathogenesis of immune-mediated myocarditis depends on genetic and environmental factors. To study the genetic mechanisms, we have developed a model of experimental autoimmune myocarditis in the A.SW mouse. Here we provide evidence that loci on murine chromosome 6, and possibly chromosome 1, are involved in regulating susceptibility. Moreover, these loci overlap with loci implicated in other autoimmune diseases including diabetes in the NOD mouse. These two loci also regulate apoptosis in thymocytes as well as peripheral T cells in the NOD mouse, and we report further that A.SW mice demonstrate the same characteristics in apoptosis. These results suggest that common pathogenetic mechanisms involving apoptosis of both thymic and peripheral T cells are shared by multiple autoimmune diseases.
OBJECTIVE: To investigate the feasibility of reconstruction of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) with hamstring tendons knot implant fixation. METHODS: Fifty-two cases of ACL and PCL old injury were reconstructed under the arthroscopy with double bundles hamstring tendons knot implant fixated in the bottle-necked femoral tunnel. The tibia side were fixated by tendon weave suture cross tied a knot at the bone bridge of tibia. In this group reconstruction of ACL was in 25, PCL and ACL at the same time reconstruction in 15, PCL in 12. The failure test and displacement evaluation were used to study the biomechanics of reconstruction of ACL by hamstring tendon knot implant fixation (n = 13) in porcine knees. The control group were reconstructed with bone-patellar tendon-bone B-PT-B and interference screw (n = 11). The tibia side tendon weave suture immobility by cross tied a knot at the tibia bone bridge (n = 7) and interference screw in the tibia tunnel (n = 8). RESULTS: Forty-nine cases were followed up, average 14.6 months. The results of Lanchman test was negative in 46 cases, positive in 3 cases. Preoperative Lysholm score was 56.7, and postoperative was 92.8. According to the knee joint effective evaluate standard, 46 were excellent and 3 good. The maximal pull-out force of hamstring tendons knot implanted fixation had been greater than B-PT-B fixation by interference screw. There were similar displacement in 100 N and 400 N load between hamstring tendons knot implant fixation and B-PT-B (P > 0.05). Peak force test maximal displacement evaluation and failure energy absorption measurement showed that hamstring tendons knot implant fixation was significantly greater than B-PT-B (P < 0.01). The failure test and displacement evaluation of tendon fixation by weave suture knot at the tibia bone bridge cross tie were greater than B-PT-B fixation by interference screw. CONCLUSION: The methods of reconstruct of ACL and PCL by hamstring tendons knot implant fixation are feasible. The advantages include: it is biological fixation, not machine fixation; it may benefit for tendons with bone tunnel healing and decrease medical cost. Decreasing or eliminating displacement is helpful to prevent relaxation after reconstruction of ACL and PCL.
Transections of the entorhinal afferent fibers to hippocampus, perforant path (PP), result in the denervation in specific hippocampal subregions, which is followed by a series of plastic events including axon sprouting and reactive synaptogenesis. Many growth-associated molecules are thought to participate in these events. In the present study, we proved the upregulation of ephrin-A2 in the denervated areas of the ipsilateral hippocampus following PP transections. Interestingly, when the elevation of ephrin-A2 reached the maximum axon sprouting in the denervated areas almost finished, implying the possible inhibitory effect of ephrin-A2 on sprouting. In addition, ephrin-A2 expression was observed in synapses during reactive synaptogenesis, suggesting that this molecule might also be implicated in the formation and maturation of synapses in the denervated areas.
AIM: Chronic hepatitis B virus (HBV) infection is predominantly treated with interferon alpha (IFN-alpha), which results in an efficient reduction of the viral load only in 20-40% of treated patients. Mutations at HBV precore prevail in different clinical status of HBV infection. The roles of precore mutation in the progression of chronic hepatitis and interferon sensitivity are still unknown. The aim of this study was to explore if there was any relationship between HBV precore mutation and sensitivity to interferon in vitro. METHODS: HBV replication-competent recombinant constructs with different patterns of precore mutations were developed. Then the recombinants were transiently transfected into hepatoma cell line (Huh7) by calcium phosphate transfection method. With or without IFN, viral products in culture medium were collected and quantified 3 d after transfection. RESULTS: We obtained 4 recombinant constructs by orientation-cloning 1.2-fold-overlength HBV genome into pUC18 vector via the EcoRI and Hind III and PCR mediated site-directed mutagenesis method. All the recombinants contained mutations within precore region. Huh7 cells transfected with recombinants secreted HBsAg and HBV particles into the cell culture medium, indicating that all the recombinants were replication-competent. By comparing the amount of HBV DNA in the medium, we found that HBV DNA in medium reflecting HBV replication efficiency was different in different recombinants. Recombinants containing precore mutation had fewer HBV DNAs in culture medium than wild type. This result showed that recombinants containing precore mutation had lower replication efficiency than wild type. HBV DNA was decreased in pUC18-HBV1.2-WT recombinants after IFN was added while others with precore mutations were not, indicating that HBV harboring precore mutation was less sensitive to IFN in cell culture system. CONCLUSION: These data indicate that HBV harboring precore mutation may be resistant to IFN in vitro.
Cofilin, an essential regulator of actin filament dynamics, is inactivated by phosphorylation at Ser-3 and reactivated by dephosphorylation. Although cofilin undergoes dephosphorylation in response to extracellular stimuli that elevate intracellular Ca2+ concentrations, signaling mechanisms mediating Ca2+-induced cofilin dephosphorylation have remained unknown. We investigated the role of Slingshot (SSH) 1L, a member of a SSH family of protein phosphatases, in mediating Ca2+-induced cofilin dephosphorylation. The Ca2+ ionophore A23187 and Ca2+-mobilizing agonists, ATP and histamine, induced SSH1L activation and cofilin dephosphorylation in cultured cells. A23187- or histamine-induced SSH1L activation and cofilin dephosphorylation were blocked by calcineurin inhibitors or a dominant-negative form of calcineurin, indicating that calcineurin mediates Ca2+-induced SSH1L activation and cofilin dephosphorylation. Importantly, knockdown of SSH1L expression by RNA interference abolished A23187- or calcineurin-induced cofilin dephosphorylation. Furthermore, calcineurin dephosphorylated SSH1L and increased the cofilin-phosphatase activity of SSH1L in cell-free assays. Based on these findings, we suggest that Ca2+-induced cofilin dephosphorylation is mediated by calcineurin-dependent activation of SSH1L.
BACKGROUND: T cell factor-4 (TCF-4) plays an important role in development and carcinogenesis. Recently, the role of TCF-4 has been described in colon cancer and other cancers. However, whether TCF-4 plays a similar role in lung cancer is unknown. To answer this question, we studied the expression of TCF-4 protein and mRNA in non-small-cell lung cancer (NSCLC) and the relation of TCF-4 expression pattern to histological type and cell differentiation. METHODS: Tissue samples from sixty cases of pathologically diagnosed NSCLC and eight normal tissue samples were obtained between September 2001 and March 2003. Immunohistochemistry was used to investigate the distribution of TCF-4 protein. The staining patterns of the tumors were divided into 4 categories: nuclear staining alone or nuclear staining greater than cytoplasmic staining; cytoplasmic staining or cytoplasmic staining greater than nuclear staining; equal nuclear and cytoplasmic staining; no nuclear staining or cytoplasmic staining. The integrated optical density (OD) values of all sections were analyzed by UIC MetaMorph image analysis software. The expression of TCF-4 mRNA was detected by one-step reverse transcription-polymerase chain reaction (RT-PCR). The integrated density values of the PCR products were analyzed semi-quantitatively. RESULTS: Immunohistochemistry showed that there was no expression of TCF-4 in normal tissue. However, TCF-4 was expressed in 86.7% (52/60) of NSCLC samples, mainly in the nuclei of tumor cells. Furthermore, there was a significant difference in TCF-4 localization patterns between squamous cell carcinomas and adenocarcinomas (P < 0.05). The integrated OD values of TCF-4 expression was significantly higher in tumors with moderate-poor cell differentiation than in well differentiated tumors (51.63 +/- 6.67 vs 46.13 +/- 12.31, P < 0.01). There was no TCF-4 mRNA expression in normal tissue. However, 63.9% (23/36) of carcinoma samples expressed TCF-4 mRNA. TCF-4 mRNA expression was significantly higher in tumors with moderate-poor cell differentiation than in well differentiated tumors (P < 0.05). There were no significant differences in mRNA expression in comparison with histological type. CONCLUSIONS: The sub-cellular distribution of TCF-4 may correlate with NSCLC histological type. High expression of TCF-4 mRNA and protein may be associated with the degree of cell differentiation in NSCLC.
Cells acquire cholesterol in part by endocytosis of cholesteryl ester containing lipoproteins. In endosomes and lysosomes cholesteryl ester is hydrolyzed by acidic cholesteryl ester hydrolase producing cholesterol and fatty acids. Under certain pathological conditions, however, such as in atherosclerosis, excessive levels of cholesteryl ester accumulate in lysosomes for reasons that are poorly understood. Here, we have studied endosomal and lysosomal cholesteryl ester metabolism in cultured mouse macrophages and with cell-free extracts. We show that net hydrolysis of cholesteryl ester is coupled to the transfer of cholesterol to membranes. When membrane cholesterol levels are low, absorption of cholesterol effectively drives cholesteryl ester hydrolysis. When cholesterol levels in acceptor membranes approach saturation or when cholesterol export is blocked, cholesterol is re-esterified in endosomes. These results reveal a new facet of cellular cholesterol homeostasis and provide a potential explanation for cholesteryl ester accumulation in lysosomes of atherosclerotic cells.
Gametogenetin (Ggn) is a testicular germ cell-specific gene specifically expressed from late pachytene spermatocytes through round spermatids. The function of gametogenetin protein 1 (GGN1) remains unknown. Here, we used the yeast two-hybrid approach to look for more GGN1 interacting proteins. We found that gametogenetin binding protein 1 (GGNBP1), gametogenetin binding protein 2 (GGNBP2) and ornithine decarboxylase antizyme 3 (OAZ3) were potential GGN1 interaction partners. We determined the regions mediating the interactions and further showed the interactions between the proteins in mammalian cells by colocalization and coimmunoprecipitation experiments. Our work suggested that GGN1, GGNBP1, GGNBP2 and OAZ3 could be involved in a common process associated with spermatogenesis.