Biomedical subjects

J F Wang

Publications and source records attributed to J F Wang.

At least 37 records · Page 2Linked to original sources

PubMed2001

Molecular scaffold of a new pokeweed antifungal peptide deduced by 1H nuclear magnetic resonance.

The antifungal peptide from seeds of Phytolacca americana (Pokeweed), designated PAFP-S hereinafter, is a recently found cationic peptide which consists of 38 amino acid residues and exhibits a broad spectrum of antifungal activity, including inhibition of certain saprophytic fungi and some plant pathogens. The secondary structure and three cysteine pairings have been investigated by 1H NMR analysis. The results show that the molecular scaffold of PAFP-S features a triple-stranded antiparallel beta-sheet knotted by a typical disulfide bridge motif, which characterizes the knottin fold. CD spectroscopy indicates a high stability of the molecule in solution. Therefore, PAFP-S should be a new member of the knottin structural family and the first antifungal peptide that adopts the knottin-like fold.

Amino Acid Motifs↗

PubMed2001

Solution structure of PAFP-S: a new knottin-type antifungal peptide from the seeds of Phytolacca americana.

The three-dimensional solution structure of PAFP-S, an antifungal peptide extracted from the seeds of Phytolacca americana, was determined using 1H NMR spectroscopy. This cationic peptide contains 38 amino acid residues. Its structure was determined from 302 distance restraints and 36 dihedral restraints derived from NOEs and coupling constants. The peptide has six cysteines involved in three disulfide bonds. The previously unassigned parings have now been determined from NMR data. The solution structure of PAFP-S is presented as a set of 20 structures using ab initio dynamic simulated annealing, with an average RMS deviation of 1.68 A for the backbone heavy atoms and 2.19 A for all heavy atoms, respectively. For the well-defined triple-stranded beta-sheet involving residues 8-10, 23-27, and 32-36, the corresponding values were 0.39 and 1.25 A. The global fold involves a cystine-knotted three-stranded antiparallel beta-sheet (residues 8-10, 23-27, 32-36), a flexible loop (residues 14-19), and four beta-reverse turns (residues 4-8, 11-14, 19-22, 28-32). This structure features all the characteristics of the knottin fold. It is the first structural model of an antifungal peptide that adopts a knottin-type structure. PAFP-S has an extended hydrophobic surface comprised of residues Tyr23, Phe25, Ile27, Tyr32, and Val34. The side chains of these residues are well-defined in the NMR structure. Several hydrophilic and positively charged residues (Arg9, Arg38, and Lys36) surround the hydrophobic surface, giving PAFP-S an amphiphilic character which would be the main structural basis of its biological function.

Amino Acid Sequence↗

PubMed2001

Stimulation of beta 1 integrin induces tyrosine phosphorylation of vascular endothelial growth factor receptor-3 and modulates cell migration.

Interactions between integrins and tyrosine kinase receptors can modulate a variety of cell functions. We observed a cooperative interaction between the beta(1) integrin and vascular endothelial growth factor receptor-3 (VEGFR-3 or Flt4) that appeared to be required for cell migration. By using VEGFR-3-transfected 293 cells (293/VEGFR-3) or primary dermal microvascular endothelial cells (DMEC), we found that stimulation with either soluble or immobilized extracellular matrix (ECM) proteins, collagen or fibronectin (FN), resulted in the increased tyrosine phosphorylation of VEGFR-3 in the absence of a cognate ligand. This increased tyrosine phosphorylation of VEGFR-3 was diminished by pretreatment with a blocking antibody against the beta(1) integrin. Cross-linking with anti-beta(1) integrin antibody induced a similar degree of tyrosine phosphorylation of VEGFR-3. Stimulation with collagen or FN induced an association between beta(1) integrin and VEGFR-3 in both 293/VEGFR-3 and primary DMEC cells. Collagen or FN-induced tyrosine phosphorylation of VEGFR-3 was inhibited by treatment with cytochalasin D, an inhibitor of actin polymerization. Collagen or FN was able to induce the migration of 293/VEGFR-3 or DMEC cells to a limited extent. However, migration was dramatically enhanced when a gradient of the cognate ligand, VEGF-D, was added. VEGF-D failed to induce cell migration in the absence of ECM proteins. Introducing a mutation at the kinase domain of VEGFR-3 or treatment with blocking antibody against either VEGFR-3 or beta(1) integrin inhibited cell migration induced by ECM and VEGF-D, indicating that signals from both beta(1) integrin and VEGFR-3 are required for this cell function.

Cell Movement↗

PubMed2001

Increased hippocampal BDNF immunoreactivity in subjects treated with antidepressant medication.

BACKGROUND: The cAMP signaling pathway, and its downstream neurotrophic factor BDNF, are major targets of antidepressant medications. Abnormalities in this pathway have previously been reported in postmortem brain of subjects with mood disorders. This study was designed to test whether the diagnosis of a mood disorder, or treatment with an antidepressant or mood stabilizer was associated with changes in hippocampal BDNF in postmortem brain. METHODS: Frozen postmortem anterior hippocampus sections were obtained from the Stanley Foundation Neuropathology Consortium. Tissue from subjects with major depression, bipolar disorder, schizophrenia and nonpsychiatric control subjects were stained for BDNF using immunohistochemistry. RESULTS: Increased BDNF expression was found in dentate gyrus, hilus and supragranular regions in subjects treated with antidepressant medications at the time of death, compared with antidepressant-untreated subjects. Furthermore, there was a trend toward increased BDNF expression in hilar and supragranular regions in depressed subjects treated with antidepressants, compared with the subjects not on these medications at the time of death. CONCLUSIONS: These findings are consistent with recent studies measuring CREB levels in this same subject sample, and support current animal and cellular models of antidepressant function.

Adult↗

PubMed2001

Metoprolol attenuates postischemic depressed myocardial function in papillary muscles isolated from normal and postinfarction rat hearts.

The present study was designed to test the hypothesis that metoprolol treatment may enhance tolerance to ischemia in normal and postinfarction rat myocardium. Myocardial infarction was induced by permanent ligation of the left coronary artery in adult rats. Animals were divided into sham-operated and infarction groups with or without metoprolol treatment. Metoprolol treatment (60 mg/kg/day via gastric gavage) was started on the second day after surgery and continued until sacrifice at 6 weeks after myocardial infarction. Isometric force and intracellular Ca(2+) ([Ca(2+)](i)) transients were simultaneously recorded in isolated left ventricular papillary muscles. Ischemia was simulated by immersing the muscles into fluorocarbon with hypoxia. Metoprolol treatment induced a significant improvement of isometric force and ameliorated diastolic [Ca(2+)](i) overload in postinfarction rat myocardium at baseline. Metoprolol treatment also reduced diastolic [Ca(2+)](i), ameliorated the depression of developed tension during ischemia, and enhanced recovery of postischemic depressed myocardial function in sham-operated and postinfarction rat papillary muscles. Protein levels of the sarcoplasmic reticulum Ca(2+) ATPase of left ventricles and postischemic papillary muscles from metoprolol-treated rats were higher than those in placebo-treated animals. We concluded, therefore, that metoprolol treatment produced appreciable improvement of intracellular Ca(2+) handling during ischemia-reoxygenation cycles, and enhanced recovery of postischemic depressed myocardial function in both normal and postinfarction rat myocardium.

Adrenergic beta-Antagonists↗

PubMed2001

Janus kinase 2 is involved in stromal cell-derived factor-1alpha-induced tyrosine phosphorylation of focal adhesion proteins and migration of hematopoietic progenitor cells.

Stromal cell-derived factor-1 (SDF-1), the ligand for the CXCR4 receptor, is a highly efficacious chemoattractant for CD34(+) hematopoietic progenitor cells. However, the SDF-1/CXCR4 signaling pathways that regulate hematopoiesis are still not well defined. This study reports that SDF-1alpha can stimulate the tyrosine phosphorylation of Janus kinase 2 (JAK2) and other members of the JAK/signal transduction and activation of transcription (STAT) family, including JAK1, tyrosine kinase 2, STAT2, and STAT4 in the human progenitor cell line, CTS. SDF-1alpha stimulation of these cells also enhanced the association of JAK2 with phosphatidylinositol 3 (PI3)-kinase. This enhanced association was abolished by pretreatment of cells with AG490, a specific JAK2 inhibitor. Furthermore, pretreatment of CTS cells with AG490 significantly inhibited SDF-1alpha-induced PI3-kinase activity, and inhibition of JAK2 with AG490 ablated the SDF-1alpha-induced tyrosine phosphorylation of multiple focal adhesion proteins (including focal adhesion kinase, related adhesion focal tyrosine kinase, paxillin, CrkII, CrkL, and p130Cas). Chemotaxis assays showed that inhibition of JAK2 diminished SDF-1alpha-induced migration in both CTS cells and CD34(+) human bone marrow progenitor cells. Hence, these results suggest that JAK2 is required for CXCR4 receptor-mediated signaling that regulates cytoskeletal proteins and cell migration through PI3-kinase pathways in hematopoietic progenitor cells. (Blood. 2001;97:3342-3348)

Adaptor Proteins, Signal Transducing↗

PubMed2001

HIV-1 Tat promotes monocyte chemoattractant protein-1 secretion followed by transmigration of monocytes.

The mechanism whereby HIV-infected cells transit from the bloodstream into tissues is not well defined. This phenomenon was addressed by studying the effects of HIV-1 Tat, a protein secreted by infected cells, on human lung microvascular endothelial cells (HMVEC-Ls). It was found that monocyte chemoattractant protein-1 (MCP-1) was released from HMVEC-Ls in a dose- and time-dependent manner after Tat treatment. MCP-1 is a potent beta-chemokine that recruits monocytes and T cells and promotes cell adhesion and transmigration across an endothelial monolayer. It was also observed that MCP-1 and the culture medium from Tat-treated HMVEC-Ls were chemotactic for CD14(+) monocytes from human peripheral blood and for THP-1, a promonocytic cell line used as a model system. To characterize the signaling pathways underlying the observed induction of MCP-1, HMVEC-Ls were treated with 2 different protein kinase inhibitors: PD98059, a MAP kinase inhibitor, and GF109203X, a protein kinase C (PKC) inhibitor. MCP-1 release was significantly reduced when PKC was inhibited, and slightly decreased when PI3 kinase was blocked; no effect on MCP-1 release was observed on MAP kinase inhibition. Similarly, transmigration of THP-1 cells was significantly impaired by the PKC inhibitor, but not by the other tested inhibitors. These data indicate that the HIV-1 Tat protein may act as a protocytokine by causing the release of MCP-1 from the endothelial monolayer, and thereby facilitating monocyte transmigration into tissues via a PKC signaling pathway.

Cell Culture Techniques↗

PubMed2001

Determination of retinoids in human serum, tocopherol and retinyl acetate in pharmaceuticals by RP-LC with electrochemical detection.

A liquid chromatography with a electrochemical detector method has been developed of the quantitative measurement for the three retinoids in human serum (13-cis and all-trans retinoic acid and retinol), as well as tocopherol acetate, retinyl acetate and retinol in pharmaceuticals. The detection cell consisted of a glassy carbon electrode held at 1.0 V versus an Ag/AgCl reference electrode. The maximum electrochemical signal was obtained with a supporting electrolyte containing 92% methanol 0.1 M acetate buffer (pH 4.72) as the mobile phase. The quantification limits are 0.5, 0.2, 0.4, 0.5, 0.8 and 0.8 ng for tocopherol acetate, all-trans-RA, 13-cis-RA, retinol, retinal and retinyl acetate, respectively. The electrooxidation process is applied for the simultaneous quantitative determination of retinoids in human serum. Comparison with results obtained from HPLC-UV shows agreement.

Adult↗

PubMed2001

Identification of mood stabilizer-regulated genes by differential-display PCR.

An increasing body of evidence demonstrates that lithium and valproate have a regulatory effect on signal transduction pathways. Alteration of signalling molecules triggers changes in gene expression which are thought to contribute to the therapeutic effects of these drugs on bipolar disorder. Differential-display PCR was used to identify genes in rat cerebral cortex that are regulated by chronic treatment with lithium and valproate. One novel lithium-regulated gene was identified and was characterized and studied further with 5'-RACE-PCR and library screening. We also found that valproate regulated the expression of the 78-kDa glucose-regulated protein (GRP78). Chronic treatment with valproate has also been found to increase gene transcription, mRNA and protein levels of GRP78. These results suggest novel targets for lithium and valproate that may be relevant to their mechanism of action. The data further our understanding of the mechanism of the action of mood stabilizers, and help identify new targets for genetic studies and therapeutic strategies in bipolar disorder.

Animals↗

PubMed2001

Attenuated lapinized chinese strain of classical swine fever virus: complete nucleotide sequence and character of 3'-noncoding region.

The complete nucleotide sequence including precise 5'- and 3'-terminal non-coding regions (NCRs) of the attenuated lapinized Chinese strain (HCLV) of Classical Swine Fever Virus (CSFV) was determined from overlapping cDNA clones constructed by separated RT-PCR and rapid amplification of cDNA ends (RACE) methods. The genomic RNA of the HCLV strain consists of 12.310 nucleotides (nts) including 374 nts and 242nts in the 5'- and 3'-NCRs, respectively. It contains one large open reading frame (ORF) encoding a polyprotein of 3,898 amino acids with a calculated molecular weight of 437.6 kDa. There is one notable insertion of 12 continuous nts, CTTTTTTCTTTT in the 3'-NCR of HCLV genomic cDNA when compared with its parental virulent Shimen strain. Sequence alignment of partial 3'-NCR reveals two groups of CSFV vaccine strains carrying similar T-rich insertions at different positions in this region. Computer-predicted secondary structures suggest that T-rich insertion greatly change the structures and thus decrease the promoter functions of 3'-NCRs during the replications of these two groups of CSFV vaccine strains.

3' Untranslated Regions↗

PubMed2001

Gene expression differences in bipolar disorder revealed by cDNA array analysis of post-mortem frontal cortex.

Previous studies have implicated a number of biochemical pathways in the etiology of bipolar disorder (BD). However, the precise abnormalities underlying this disorder remain to be established. To investigate novel factors that may be important in the pathophysiology of BD, we utilized cDNA expression arrays to examine differences in expression of up to 1200 genes known to be involved in potentially relevant biochemical processes. This investigation was undertaken in post-mortem samples of frontal cortex tissue from patients with BD and matched controls, obtained (n = 10/group) from the Stanley Foundation Neuropathology Consortium. Results include significant (greater than 35% change in signal intensity) differences between BD and controls in a number of genes (n = 24). Selected targets were analyzed by RT-PCR, which confirmed a decrease in transforming growth factor-beta1 (TGF-beta 1), and an increase in both caspase-8 precursor (casp-8) and transducer of erbB2 (Tob) expression in BD. We further observed a significant decrease of TGF-beta 1 mRNA levels in BD by RT-PCR in individual post-mortem samples. Given the neuroprotective role attributed to this inhibitory cytokine, our results suggest that the down-regulation of TGF-beta 1 may lead to various neurotoxic insults potentially involved in the etiology of certain mood disorders.

Adult↗

PubMed2001

Chocolate procyanidins decrease the leukotriene-prostacyclin ratio in humans and human aortic endothelial cells.

BACKGROUND: Polyphenolic phytochemicals inhibit vascular and inflammatory processes that contribute to disease. These effects are hypothesized to result from polyphenol-mediated alterations in cellular eicosanoid synthesis. OBJECTIVE: The objective was to determine and compare the ability of cocoa procyanidins to alter eicosanoid synthesis in human subjects and cultured human aortic endothelial cells. DESIGN: After an overnight fast, 10 healthy subjects (4 men and 6 women) consumed 37 g low-procyanidin (0.09 mg/g) and high-procyanidin (4.0 mg/g) chocolate; the treatments were separated by 1 wk. The investigation had a randomized, blinded, crossover design. Plasma samples were collected before treatment and 2 and 6 h after treatment. Eicosanoids were quantitated by enzyme immunoassay. Endothelial cells were treated in vitro with procyanidins to determine whether the effects of procyanidin in vivo were associated with procyanidin-induced alterations in endothelial cell eicosanoid synthesis. RESULTS: Relative to the effects of the low-procyanidin chocolate, high-procyanidin chocolate induced increases in plasma prostacyclin (32%; P<0.05) and decreases in plasma leukotrienes (29%; P<0.04). After the in vitro procyanidin treatments, aortic endothelial cells synthesized twice as much 6-keto-prostaglandin F(1alpha) (P<0.01) and 16% less leukotriene (P<0.05) as did control cells. The in vitro and in vivo effects of procyanidins on plasma leukotriene-prostacyclin ratios in culture medium were also comparable: decreases of 58% and 52%, respectively. CONCLUSION: Data from this short-term investigation support the concept that certain food-derived flavonoids can favorably alter eicosanoid synthesis in humans, providing a plausible hypothesis for a mechanism by which they can decrease platelet activation in humans.

Adult↗

PubMed2001

Physician control of pediatric antimicrobial use in Beijing, China, and its rural environs.

BACKGROUND: Antibiotic resistance is recognized as an increasing problem in China. It is widely believed that because antibiotics are available without a prescription, changing physician prescribing behaviors will not decrease inappropriate usage. This study identified the sources of antibiotics and the important influence that physicians have on antibiotic use by children in one region of China. METHODS: Trained medical professionals surveyed parents of children attending several kindergartens in urban Beijing and rural Gu'An, Hebei County. Parents completed a questionnaire concerning the children's recent illnesses, care-seeking patterns and antibiotic use. The team also observed hospital- and non-hospital-based pharmacy purchases of antibiotics for children, assessed the proportion accompanied by a prescription and then interviewed parents about factors influencing those purchases. RESULTS: Of 241 urban and 143 rural kindergarten parents, 76 to 82% usually obtained children's antibiotics from a hospital pharmacy (with a prescription). For 84% the first source of care was usually a physician (primarily western medicine, sometimes traditional Chinese medicine). Only 5% of antibiotics were obtained from independent vendors without prior physician consultation. Among 229 observed antibiotic purchases 72% occurred at hospital-based facilities, even after longer observation times at nonhospital pharmacies. Prescriptions accompanied all hospital-based antibiotic purchases, contrasting with 18% of nonhospital transactions (P < 0.001). Together 86% of parents self-reported that the observed purchase stemmed from a doctor's recommendation. CONCLUSIONS: Doctors directly and indirectly controlled the majority of antibiotic usage for childhood illnesses in Beijing and Gu'An (Hebei County). Physician education and implementation of treatment guidelines might substantially reduce inappropriate antimicrobial usage and help prevent antimicrobial resistance in this region.

Anti-Bacterial Agents↗

PubMed2001

Differential patterns of cocaine-induced organ toxicity in murine heart versus liver.

To determine cocaine's toxicity in different organs, BALB/c mice were intraperitoneally injected daily for 15 days with either saline or cocaine: 10 mg/kg, 30 mg/kg, or 60 mg/kg. Cardiac function, hepatic pathophysiology, heart and liver apoptosis, and tumor necrosis factor (TNF-alpha) levels were analyzed. After administration of cocaine, cardiac function decreased. Inflammatory cell infiltration and eosinophilic contraction bands were visible in the hearts of mice treated with 60mg/kg cocaine. Moreover, histopathology demonstrated that cocaine caused hepatic necrosis. TdT-mediated dUTP nick end-labeling (TUNEL) staining and DNA ladder analysis indicated that cocaine caused apoptosis in both the heart and liver. Moreover, immunoassay showed that TNF-alpha levels significantly increased in the heart and liver with cocaine administration. However, our RT-PCR study showed that there was no significant difference in either the heart or liver in the levels of mRNA for TNF-alpha between cocaine-treated and saline control mice. The present study demonstrated that cocaine is toxic to multiple organs, and at low dose can induce hepatic damage without gross pathological injury to the heart. The results suggest that the liver is more sensitive than the heart to cocaine toxicity, and induction of apoptosis or TNF-alpha elevation may be a common mechanism responsible for cocaines toxicity.

Alanine Transaminase↗

PubMed2001

[Purification and biological activity of rh-leptin expressed in Escherichia coli].

The human leptin was successfully expressed with high level in E. coli under the control of PL promotor. The yield of recombinant protein was over 40% of total cellular protein and expressed as inclusion bodies. The recombinant human leptin (rh-leptin) was purified with gel filtration, anion-exchange and reverse chromatography. Refolding was achieved by gradually reducing denaturant using a diafiltration method. The refolded rh-leptin was characterized by SDS-PAGE, Western-blotting and its first 15 amino acid residues sequence of the N-terminal. The purified product was found to be biologically active, reducing the food intake and body weight gain upon testing in BALB/c mice.

Animals↗

PubMed2001

[Anterior lumbar interbody fusion of canine with allograft cortical ring plus autogenous cancellus].

OBJECTIVE: To prove the biological characteristics of spinal intervertebral fusion with allograft cortical ring plus autogenous cancellus from iliac bone (called as composite ring). METHODS: Eight hybrid dogs were adopted in the study. The composite ring and autogenous tri-cortical blocks were implanted into the intervertebral space of dogs respectively. The intervertebral discs were removed before implantation. The fusion segments were evaluated by x-ray, histological examinations at 1, 2, 4 and 6 months after operation to compare the healing status of two implants. RESULTS: The X-ray film and histological examination showed the lumbar interbody was fused after 4 months of operation in composite ring group, while the autogenous iliac bone blocks fused with peripheral bone tissue after 6 months of operation. Composite ring healed more quickly and completely, showed different osteogenesis behavior compared with that of massive allografts. CONCLUSION: Composite ring can promote the fusion of intervertebral body and can be used as a potential material for spinal surgery.

Animals↗

PubMed2001

[Studies of mtDNA haplotype polymorphism of Rongcheng population in China].

The loss of one copy of two 9-bp repeats in mtDNA non-coding region V is often found in Asia and Pacific populations. Two hundred and ten samples from Rongcheng county, Shandong province were detected with the deletion frequency of 12.4%. A distribution map of frequencies of mtDNA 9-bp deletion among Asian and Pacific population was made with reference to other published data. Further discussion was made for the hypotheses of affinity and original model of those populations. PCR-RFLP was conducted to obtain the mtDNA polymorphism information in five other mtDNA regions except the 9-bp deletion in 95 samples. Twenty-seven different mtDNA haplotypes were found, and the relationships among these haplotypes have been analyzed by using MEGA2.0 and PHYLIP 3.57. Two new RFLP sites caused by point mutation were also found, which have not been reported in Chinese populations.

Adolescent↗

PubMed2001

The pig as a model for excisional skin wound healing: characterization of the molecular and cellular biology, and bacteriology of the healing process.

A pig model of wound healing was developed by excision of 2-cm-diameter full thickness skin in young Yorkshire pigs. The results indicated that wound re-epithelialization in this animal model took an average of 20 days. Analysis of cellular change was assessed by use of DNA quantification and determination of apoptotic cells in tissue sections. The results indicate that RNA and DNA contents paralleled each other throughout the healing process, and observed changes in the pattern of RNA and DNA content of the scar tissues were consistent with cell loss due to apoptosis in this model. Expression of mRNA for relevant genes was assessed by use of semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis, using porcine specific primer sets and RNA isolated from normal skin and specimens obtained at various times after wounding. The mRNA values for tumor necrosis factor-alpha (TNF-alpha), connective tissue growth factor (CTGF), insulin-like growth factor II (IGF-II), and decorin were significantly high at specific times after wounding, but mRNA values for the transcription factors (c-fos and c-jun) were significantly decreased. Quantitative bacteriologic results indicated that the total bacterial count in this animal model reached 10(9) colony-forming units (CFU)/g, with the highest value at post-wounding day 7, and Pseudomonas aeruginosa and Staphylocococci aureus were the most common bacteria detected in this model. Further definition of this model should identify unique points in the healing process, and such information could lead to development of therapeutic interventions to improve skin wound healing.

Animals↗