Biomedical subjects

J F Wang

Publications and source records attributed to J F Wang.

At least 55 records · Page 3Linked to original sources

PubMed2001

[Sensitive and rapid analysis of nitrophenols and herbicides by capillary zone electrophoresis (CZE)].

11 Nitrophenols and some acidic herbicides have been separated by modified CZE. Good separation of such compounds can be achieved in less than 10 min by simply modifying the run buffer with organic solvents such as methanol, acetonitrile in a concentration of 40% (V/V). The limits of detection (LODs) for nitrophenols by UV-absorption at 215 nm were 0.5 mg/L-1.1 mg/L. Solid phase extraction was used to preconcentrate nitrophenols and some herbicides to reach an LOD at microgram/L levels. Typical samples have been analyzed.

Electrophoresis, Capillary↗

PubMed2001

[Cloning and sequencing of cytochrome c oxidase II(COII) gene of three species of mosquitoes].

OBJECTIVE: To determine and compare the complete sequence of COII gene from Anopheles sinensis, Aedes albopictus and Culex quinquefasciatus and to identify the molecular homology among these mosquitoes. METHODS: The recombinant plasmids including COII gene from the three species of mosquitoes were obtained by the T-A cloning technique, and the COII genes were sequenced and analyzed. RESULTS: The homology of the COII gene nucleotide sequence and the deduced amino acid sequence of COII among the three species of mosquitoes varied from 84.1% to 87.9% and from 85.1% to 89.5%, respectively. The C + G content of COII gene was 23.2%-24.9%, the frequency of transversion higher than that of transition. CONCLUSION: Aedes albopictus and Culex quinquefasciatus are closely related species at their COII molecular level according to COII gene.

Aedes↗

PubMed2000

Increased hippocampal supragranular Timm staining in subjects with bipolar disorder.

Biochemical and structural abnormalities have been reported in hippocampus of subjects with mood disorders. This study examined the organization of mossy fibers in anterior hippocampus of subjects obtained from the Stanley Neuropathology Consortium. Frozen postmortem hippocampal sections from subjects with major depression, bipolar disorder, schizophrenia and non-psychiatric controls were stained using the Neo-Timm procedure, which selectively stains mossy fibers. Increased Timm staining in the supragranular layer was found in subjects with bipolar disorder relative to control subjects. These results are suggestive of neuronal sprouting in hippocampus of subjects with bipolar disorder. There were no significant associations between supragranular Timm staining and suicide, length illness or drug treatment at the time of death.

Adult↗

PubMed2000

Chronic valproate treatment increases expression of endoplasmic reticulum stress proteins in the rat cerebral cortex and hippocampus.

BACKGROUND: Sodium valproate is a highly effective treatment for bipolar disorder, but its mechanism of action remains poorly understood. We recently found with differential display polymerase chain reaction that valproate regulates the expression of the endoplasmic reticulum stress protein GRP78 in the rat cerebral cortex. In our study, we investigated the effect of this drug on the other members of the endoplasmic reticulum stress protein family, GRP94 and calreticulin, and we studied the brain regional distribution of GRP78, GRP94, and calreticulin. METHODS: Immunohistochemistry was used to measure protein levels of GRP78, GRP94, and calreticulin after treatment with sodium valproate (300 mg/kg, intraperitoneal) in specific rat brain regions. RESULTS: We report here that chronic treatment with valproate also increased expression of other members of the endoplasmic reticulum stress protein family, such as GRP94 and calreticulin. The brain regional distribution of these changes was similar for all three proteins, with marked increase detected in the frontal cortex, parietal cortex, and CA1 region of the hippocampus. CONCLUSIONS: Because GRP78, GRP94, and calreticulin possess molecular chaperone activity and bind Ca(2+) in the endoplasmic reticulum, the pharmacologic action of valproate may involve one or more of these processes.

Animals↗

PubMed2000

Increased expression of endoplasmic reticulum stress proteins following chronic valproate treatment of rat C6 glioma cells.

The anticonvulsant sodium valproate has been shown to be an effective treatment for bipolar disorder, however, its precise mechanism of action has yet to be determined. It has been suggested that adaptational changes in gene expression are critical for valproate's prophylactic effects. Previous studies in our lab have shown that one gene that may be regulated by valproate is the 78-kilodalton glucose-regulated protein (GRP78). We report that treatment of rat C6 glioma cells with valproate can also increase the expression of additional endoplasmic reticulum stress proteins, GRP94 and calreticulin. All three proteins showed similar concentration-dependent increases in messenger RNA abundance. Chronic (seven days) treatment significantly increased GRP78 and GRP94 messenger RNA expression, whereas calreticulin expression increased after both acute and chronic treatment. Increases in mRNA expression corresponded to a similar increase in protein expression. The roles of GRP78, GRP94 and calreticulin as molecular chaperones and calcium binding proteins, suggest that these results might have functional relevance to the therapeutic action of valproate.

Animals↗

PubMed2000

Stromal cell-derived factor-1alpha stimulates tyrosine phosphorylation of multiple focal adhesion proteins and induces migration of hematopoietic progenitor cells: roles of phosphoinositide-3 kinase and protein kinase C.

The stromal cell-derived factor-1 (SDF-1) is an alpha chemokine that binds to the CXCR4 receptor. Knock-out studies in mice demonstrate that this ligand-receptor pair is essential in hematopoiesis. One function of SDF-1 appears to be the regulation of migration of hematopoietic progenitor cells. We previously characterized signal transduction pathways induced by SDF-1alpha in human hematopoietic progenitors and found tyrosine phosphorylation of focal adhesion components, including the related adhesion focal tyrosine kinase (RAFTK), the adaptor molecule p130 Cas, and the cytoskeletal protein paxillin. To better understand the functional role of signaling molecules connecting the CXCR4 receptor to the process of hematopoietic migration, we studied SDF-1alpha-mediated pathways in a model hematopoietic progenitor cell line (CTS), as well as in primary human bone marrow CD34(+) cells. We observed that several other focal adhesion components, including focal adhesion kinase (FAK) and the adaptor molecules Crk and Crk-L, are phosphorylated on SDF-1alpha stimulation. Using a series of specific small molecule inhibitors, both protein kinase C (PKC) and phosphoinositide-3 kinase (PI-3K) appeared to be required for SDF-1alpha-mediated phosphorylation of focal adhesion proteins and the migration of both CTS and primary marrow CD34(+) cells, whereas the mitogen-activated protein kinases ERK-1 and -2 were not. These studies further delineate the molecular pathways mediating hematopoietic progenitor migration and response to an essential chemokine, SDF-1alpha. (Blood. 2000;95:2505-2513)

Animals↗

PubMed2000

Comparative morphometric evaluation of peripheral nerves and muscle fibers in myotonic dystrophy.

We compared peripheral nerve fibers and muscle fibers in myotonic dystrophy (MD) using a computer-assisted device for morphometry. In the 17 cases with MD studied, the sural nerves of 14 cases (82%) showed various degrees of reduction of the myelin sheath area (MSA) per endoneurial area. Of these, 8 cases (47%) presented with a mild reduction of the MSA, 5 cases (29.4%) with moderate reduction, and one case (6%) with severe reduction. The number of myelinated nerve fibers was not significantly reduced in MD when compared with control nerves, due to clusters of small regenerated nerve fibers. The mean diameter of the muscle fibers in 6 of the 17 cases was less than 40 microm. Of these 6 severely affected cases, 5 revealed a considerable reduction of the MSA. Other cases, which appeared to be normal in respect to the diameter of muscle fibers, showed various degrees of reduction of the MSA. Thus, there is usually, but not always a morphometric correlation of the severity of changes between peripheral nerves and muscle. The severity of the peripheral neuropathy appears to depend largely on the patient's age, the stage of the disorder, and the time of progression. Electron microscopic examination of sural nerves showed significant, though non-specific pathological changes.

Adult↗

PubMed2000

Increased temporal cortex ER stress proteins in depressed subjects who died by suicide.

Regulation of ER stress proteins, such as the 78-kilodalton glucose regulated protein (GRP78) by chronic treatment with mood stabilizing drugs suggests that this family of proteins may be involved in the pathophysiology of mood disorders. Indeed, increased levels of GRP78, GRP94, and calreticulin, a third member of the ER stress protein family, were found in temporal cortex of subjects with major depressive disorder who died by suicide compared with controls and subjects who died by other means. No such differences were found in subjects with other psychiatric disorders such as bipolar disorder or schizophrenia. These data suggest a potential role for ER stress proteins in severe depression that merits further study.

Adult↗

PubMed2000

Mice mutant for Egfr and Shp2 have defective cardiac semilunar valvulogenesis.

Atrioventricular and semilunar valve abnormalities are common birth defects, but how cardiac valvulogenesis is directed remains largely unknown. During studies of genetic interaction between Egfr, encoding the epidermal growth factor receptor, and Ptpn11, encoding the protein-tyrosine-phosphatase Shp2, we discovered that Egfr is required for semilunar, but not atrioventricular, valve development. Although unnoticed in earlier studies, mice homozygous for the hypomorphic Egfr allele waved-2 (Egfrwa2/wa2) exhibit semilunar valve enlargement resulting from over-abundant mesenchymal cells. Egfr-/- mice (CD1 background) have similar defects. The penetrance and severity of the defects in Egfrwa2/wa2 mice are enhanced by heterozygosity for a targeted mutation of exon 2 of Ptpn11 (ref. 3). Compound (Egfrwa2/wa2:Ptpn11+/-) mutant mice also show premature lethality. Electrocardiography, echocardiography and haemodynamic analyses showed that affected mice develop aortic stenosis and regurgitation. Our results identify the Egfr and Shp2 as components of a growth-factor signalling pathway required specifically for semilunar valvulogenesis, support the hypothesis that Shp2 is required for Egfr signalling in vivo, and provide an animal model for aortic valve disease.

Abnormalities, Multiple↗

PubMed2000

A dose-response effect from chocolate consumption on plasma epicatechin and oxidative damage.

Evidence from epidemiological studies suggests that a diet high in plant foods and rich in polyphenols is inversely associated with a risk for cardiovascular and other chronic diseases. Chocolate, like red wine and green tea, is a polyphenol-rich food, primarily containing procyanidin polyphenols. These polyphenols are hypothesized to provide cardioprotective effects due to their ability to scavenge free radicals and inhibit lipid oxidation. Herein, we demonstrate that 2 h after the ingestion of a procyanidin-rich chocolate containing 5.3 mg total procyanidin/g, of which 1.3 mg/g was (-)-epicatechin (epicatechin), plasma levels of epicatechin increased 133 +/- 27, 258 +/- 29 and 355 +/- 49 nmol/L in individuals who consumed 27, 53 and 80 g of chocolate, respectively. That the rise in plasma epicatechin levels was functionally significant is suggested by observations of trends for dose-response increases in the plasma antioxidant capacity and decreases in plasma lipid oxidation products. The above data support the theories that in healthy adults, 1) a positive relationship exists between procyanidin consumption and plasma procyanidin concentration and 2) the rise in plasma epicatechin contributes to the ability of plasma to scavenge free radicals and to inhibit lipid peroxidation.

Adult↗

PubMed2000

Resistance of tomato line Hawaii7996 to Ralstonia solanacearum Pss4 in Taiwan is controlled mainly by a major strain-specific locus.

Bacterial wilt caused by the soilborne bacterium Ralstonia solanacearum attacks hundreds of plant species, including many agriculturally important crops. Natural resistance to this disease has been found in some species and is usually inherited as a polygenic trait. In tomato, a model crop plant, genetic analysis previously revealed the involvement of several QTL (quantitative trait loci) controlling resistance and, in all of these studies with different strains of the pathogen, loci on chromosome 6 played the predominant role in controlling this trait. Using quantitative data collected from a greenhouse test F3 population, we identified a new locus on chromosome 12 that appears to be active specifically against a race 1 biovar 3 Pss4 bacterial strain endemic to Taiwan. Chromosome 6 still contributes significantly to the control of the resistance, and weaker associations of the trait to other regions of the genome are observed. These results are discussed in the context of current molecular knowledge about the strain specificity of disease resistance genes.

Chromosome Mapping↗

PubMed2000

Lymphocyte function-associated antigen 1 is a receptor for Pasteurella haemolytica leukotoxin in bovine leukocytes.

Pasteurella (Mannheimia) haemolytica leukotoxin (Lkt) causes cell type- and species-specific effects in ruminant leukocytes. Recent studies indicate that P. haemolytica Lkt binds to bovine CD18, the common subunit of all beta2 integrins. We designed experiments with the following objectives: to identify which member of the beta2 integrins is a receptor for Lkt; to determine whether Lkt binding to the receptor is target cell (bovine leukocytes) specific; to define the relationships between Lkt binding to the receptor, calcium elevation, and cytolysis; and to determine whether a correlation exists between Lkt receptor expression and the magnitude of target cell cytolysis. We compared Lkt-induced cytolysis in neutrophils from control calves and from calves with bovine leukocyte adhesion deficiency (BLAD), because neutrophils from BLAD-homozygous calves exhibit reduced beta2 integrin expression. The results demonstrate for the first time that Lkt binds to bovine CD11a and CD18 (lymphocyte function-associated antigen 1 [LFA-1]). The binding was abolished by anti-CD11a or anti-CD18 monoclonal antibody (MAb). Lkt-induced calcium elevation in bovine alveolar macrophages (BAMs) was inhibited by anti-CD11a or anti-CD18 MAb (65 to 94% and 37 to 98%, respectively, at 5 and 50 Lkt units per ml; P < 0.05). Lkt-induced cytolysis in neutrophils and BAMs was also inhibited by anti-CD11a or anti-CD18 MAb in a concentration-dependent manner. Lkt bound to porcine LFA-1 but did not induce calcium elevation or cytolysis. In neutrophils from BLAD calves, Lkt-induced cytolysis was decreased by 44% compared to that of neutrophils from control calves (P < 0.05). These results indicate that LFA-1 is a Lkt receptor, Lkt binding to LFA-1 is not target cell specific, Lkt binding to bovine LFA-1 correlates with calcium elevation and cytolysis, and bovine LFA-1 expression correlates with the magnitude of Lkt-induced target cell cytolysis.

Animals↗

PubMed2000

Depressed tolerance to fluorocarbon-simulated ischemia in failing myocardium due to impaired [Ca(2+)](i) modulation.

The aim of this study was to investigate the tolerance of failing myocardium from postinfarction rats to simulated ischemia. Myocardial infarction (MI) was induced by ligation of the left coronary artery in male Wistar rats. Isometric force and free intracellular Ca(2+) concentration ([Ca(2+)](i)) were measured in isolated left ventricular papillary muscles from sham-operated and post-MI animals 6 wk after surgery. Ischemia was simulated by using fluorocarbon immersion with hypoxia. Results showed that mechanical performance was depressed during the period of hypoxia in physiological salt solution (44 +/- 7% of baseline in sham vs. 30 +/- 6% of baseline in MI, P < 0.05) or ischemia (16 +/- 2% of baseline in sham vs. 9 +/- 1% of baseline in MI, P < 0.01) accompanied by no corresponding decrease of peak [Ca(2+)](i) (hypoxia: 51 +/- 8% of baseline in sham vs. 46 +/- 7% of baseline in MI, P = NS; ischemia: 47 +/- 5% of baseline in sham, 39 +/- 7% of baseline in MI, P = NS). After reoxygenation, [Ca(2+)](i) rapidly returned to near preischemic basal levels, whereas developed tension in fluorocarbon remained significantly lower. This dissociation between peak [Ca(2+)](i) and isometric contractility was more pronounced in the failing myocardium from postinfarction rats. In conclusion, more severe impairment of [Ca(2+)](i) homeostasis in the failing myocardium from postinfarction rats increases susceptibility to ischemia-reperfusion injury.

Animals↗

PubMed2000

Enhanced gene expression of Na(+)/Ca(2+) exchanger attenuates ischemic and hypoxic contractile dysfunction.

Enhanced gene expression of the Na(+)/Ca(2+) exchanger in failing hearts may be a compensatory mechanism to promote influx and efflux of Ca(2+), despite impairment of the sarcoplasmic reticulum (SR). To explore this, we monitored intracellular calcium (Ca(i)(2+)) and cardiac function in mouse hearts engineered to overexpress the Na(+)/Ca(2+) exchanger and subjected to ischemia and hypoxia, conditions known to impair SR Ca(i)(2+) transport and contractility. Although baseline Ca(i)(2+) and function were similar between transgenic and wild-type hearts, significant differences were observed during ischemia and hypoxia. During early ischemia, Ca(i)(2+) was preserved in transgenic hearts but significantly altered in wild-type hearts. Transgenic hearts maintained 40% of pressure-generating capacity during early ischemia, whereas wild-type hearts maintained only 25% (P < 0.01). During hypoxia, neither peak nor diastolic Ca(i)(2+) decreased in transgenic hearts. In contrast, both peak and diastolic Ca(i)(2+) decreased significantly in wild-type hearts. The decline of Ca(i)(2+) was abbreviated in hypoxic transgenic hearts but prolonged in wild-type hearts. Peak systolic pressure decreased by nearly 10% in hypoxic transgenic hearts and >25% in wild-type hearts (P < 0.001). These data demonstrate that enhanced gene expression of the Na(+)/Ca(2+) exchanger preserves Ca(i)(2+) homeostasis during ischemia and hypoxia, thereby preserving cardiac function in the acutely failing heart.

Animals↗

PubMed2000

Exon 5 and spermine regulate deactivation of NMDA receptor subtypes.

Deactivation of N-methyl-D-aspartate (NMDA) channels after brief agonist exposure determines the duration of their synaptic activation during excitatory neurotransmission. We performed patch-clamp recordings of L-glutamate responses from human embryonic kidney tumoral cells (HEK293) expressing NR1 subunit variants lacking exon 5 together with the NR2B subunit. These responses had deactivation components that lasted several seconds. The presence of exon 5 or spermine greatly accelerated deactivation of L-glutamate responses through alterations in desensitization. These effects were also observed at positive holding potentials and in the presence of physiological Mg(2+). Thus NR1 splicing and polyamines may have profound effects on the kinetics of NMDA receptor-mediated synaptic transmission.

Cell Line↗

PubMed2000

Analysis of in situ protease activity in chronic adult periodontitis patients: expression of activated MMP-2 and a 40 kDa serine protease.

BACKGROUND: Periodontitis is characterized by extensive destruction of the gingival tissues and associated supporting structures of the teeth. Although the pathogenesis of the various forms of this disease is not completely understood, host-derived proteases are believed to have an important role. In this study, we analyzed human tissue samples from chronic adult periodontitis patients to assess the levels of specific proteases and determine the effect of pH and tetracyclines on their activity. METHODS: Gingival tissue samples were obtained from patients with chronic adult periodontitis (probing depths ranged from 5 to 9 mm) and periodontally healthy controls. Tissue extracts were prepared and analyzed for protease activity by zymography and Western blotting. RESULTS: Maximal protease activity from clinically normal and diseased tissues was observed at pH 8. Latent matrix metalloproteinase (MMP)-9 and MMP-2 were expressed in all samples examined, while active MMP-2 was detected only in tissues obtained from patients with clinical disease. The MMP activities were differentially inhibited by derivatives of tetracycline. At pH 6, a protease with a mass of approximately 40 kDa was observed in diseased samples. The enzymatic activity was inhibited by phenylmethylsulfonyl fluoride, suggesting it is a serine protease. CONCLUSIONS: The results of the current study substantiate the proposed role of host-derived proteases in the pathogenesis of chronic adult periodontitis. Specifically, they indicate that activated MMP-2 and a 40 kDa serine protease are involved in tissue destruction associated with this form of periodontal disease and also suggest that tissue pH influences protease activity in situ.

Adult↗

PubMed2000

Molecular and cell biology of skin wound healing in a pig model.

To define the pattern of change at the molecular and cellular levels during the healing of excisional skin wounds in the skeletally immature pig, mRNA levels for relevant molecules were assessed by semiquantitative RT-PCR using porcine specific primer sets and RNA isolated from normal skin and samples at various time post-wounding. Analysis of cellular change was assessed by DNA quantification and histology of tissue sections. The results demonstrated that the changes in the pattern of RNA and DNA content of the scar tissue were consistent with the observed increasing cellularity. The mRNA levels for collagen I, III, HSP47, IL-1, TGF-beta, MMP-1, -2 and -9, TIMP-1, -2, and-4, PAI-1, versican were significantly elevated during healing; levels for biglycan and fibromodulin were not significantly altered; and the mRNA levels for TIMP-3 were depressed. These findings suggest that skin wound healing is a series of complex matrix-cell interactions that involve cellular migration and inflammation, followed by proliferation of fibroblasts with new collagen synthesis, and lastly tissue remodeling of the scar.

Animals↗

PubMed2000

A soluble fibroblast growth factor receptor is released from HL-60 promyelocytic leukemia cells: implications for paracrine growth control.

The biological activities of fibroblast growth factors (FGF) are mediated by specific cell membrane receptors (FGFR), which have three immunoglobulin-like IgG domains in the extracellular region. The carboxy-terminal segment of the third IgG domain of FGFR1 could be encoded by different exons, designated IIIa, IIIb, or IIIc. While exons IIIb or IIIc encode receptor forms with both intracellular and extracellular domains, the FGF receptor becomes potentially a secreted form lacking the intracellular domain and the transmembrane region when exon IIIa is expressed. Using reverse transcription polymerase chain reaction, we have found that mRNAs encoding the nucleotide sequences of FGFR1-IIIa and FGFR1-IIIc are expressed in HL-60 cells. FGFR1-IIIa fragment was synthesized by a glutathione S-transferase gene fusion system. The purified 33 kDa FGFR1-IIIa fragment fusion protein could bind [125I]-labelled FGF-2 in Western ligand blot analysis. Three species of proteins with the molecular weights of 82, 60, and 50 kDa were identified in serum-free, conditioned medium from HL-60 cells by Western blot using an antiserum against purified FGFR1-IIIa fragment fusion protein. Exposure to FGF-2 caused an increase in [3H]-thymidine incorporation into DNA of HL-60 cells and increased cell proliferation, but the addition of FGFR1-IIIa fragment fusion protein inhibited FGF-2-stimulated DNA synthesis and caused a dose-dependent inhibition of FGF-2-stimulated cell proliferation. The effects on DNA synthesis were partly reversed by antibody against the FGFR1-IIIa fragment. These results indicate that both cell membrane spanning and secreted FGF receptors are expressed in HL-60 cells, and that the actions of FGFs as paracrine growth factors could be modulated by secreted FGF receptor forms.

Blotting, Western↗