Biomedical subjects

Jun Wang

Publications and source records attributed to Jun Wang.

At least 145 records · Page 8Linked to original sources

PubMed2006

Syphilis among female sex workers in southwestern China: potential for HIV transmission.

OBJECTIVE: The objective of this study was to investigate the prevalence and risk factors of syphilis infection among female sex workers in a southwestern Chinese city along a drug trafficking route. METHODS: From December 2004 to January 2005, 343 female sex workers (FSWs) were recruited through community outreach and peer referring. Confidential questionnaire interviews were administered to collect information on sexual and other sexually transmitted diseases/HIV risk behaviors. Cervical and blood samples were collected to test for syphilis and HIV antibodies and Neisseria gonorrhoeae infection; Condyloma acuminatum infection was diagnosed clinically. RESULTS: Of 343 FSWs, 15.7% were infected with syphilis. The prevalence of HIV, gonorrhea, and C. acuminatum was 0.6%, 2.0%, and 1.5%, respectively. The subtype of 2 HIV-1 infections was both CRF 07BC. Nearly 10% of FSWs reported using illicit drugs. Consistent use, inconsistent use, and never use of condoms with commercial sex clients in the last month were reported by 53.9%, 38.5%, and 7.6% FSWs, respectively. Longer duration of sex work (odds ratio [OR] = 1.98; 95% confidence interval [CI] = 1.08-3.62), working at low-end establishments (OR = 2.03; 95% CI = 1.10-3.76), and if primary sex partners had sex with other women in the past 6 months (OR = 2.06; 95% CI = 1.08-3.91) were independently associated with syphilis infection. CONCLUSIONS: High prevalence of syphilis and overlapped unprotected commercial sex and drug using behaviors among FSWs along a drug-trafficking route may suggest a potential for rapid spread of HIV from injection drug users to FSWs and then to the general population and underscore the urgency of preventive interventions to break the bridge of FSWs for HIV/sexually transmitted disease spread.

Adolescent↗

PubMed2006

Effects of haplotypes in the interleukin 1beta promoter on lipopolysaccharide-induced interleukin 1beta expression.

Previous studies have indicated that there are 3 common haplotypes composed of the -1470, -511, and -31 loci in the interleukin 1beta (IL-1beta) promoter in the Chinese population. The purpose of this study was to investigate the relationship between these haplotypes and lipopolysaccharide (LPS)-stimulated IL-1beta expression by whole blood leukocytes in vitro and to evaluate the effects of these haplotypes on IL-1beta gene transcription. Genomic DNAs were obtained from 105 healthy subjects. The genotypes at the 3 sites of the IL-1beta promoter were determined by restriction fragment length polymorphism analysis. Haplotype frequency was evaluated by using the Arlequin software. Plasma IL-1beta level was measured by enzyme-linked immunosorbent assay. The transcriptional activity of the haplotypes was determined by in vitro reporter gene. The results indicated that after the exposure to LPS, whole blood leukocytes from subjects with the homozygous haplotype -1470G, -511C, and -31T (G-C-T) produced more IL-1beta in vitro than those from subjects with haplotype -1470C, -511T, and -31C (C-T-C) and that the transcriptional activity of the haplotype G-C-T was also higher than that of the haplotype C-T-C. It is suggested that the haplotypes of the IL-1beta promoter influence the expression and transcriptional activity of the IL-1beta gene and that the upregulation of IL-1beta gene expression after LPS exposure in subjects with haplotype G-C-T may be due to an increased transcriptional activity of the haplotype.

Asian People↗

PubMed2006

Multifractal ECG mapping of ventricular epicardium during regional ischemia in the pig.

Myocardial ischemia creates abnormal electrophysiological substrates that can result in life-threatening ventricular arrhythmias. Early clinical identification of ischemia in patients is important to managing their condition. We analyzed electrograms from an ischemia-reperfusion animal model in order to investigate the relationship between myocardial ischemia and variability of electrocardiogram (ECG) multifractality. Ventricular epicardial electropotential maps from the anesthetized pig during LAD ischemia-reperfusion were analyzed using multifractal methods. A new parameter called the singularity spectrum area reference dispersion (SARD) is presented to represent the temporal evolution of multifractality. By contrasting the ventricular epicardial SARD and range of singularity strength (delta alpha) maps against activation-recovery interval (ARI) maps, we found that the dispersions of SARD and dleta alpha increased following the onset of ischemia and decreased with tissue recovery. In addition, steep spatial gradients of SARD and delta alpha corresponded to locations of ischemia, although the distribution of multifractality did not reflect the degree of myocardial ischemia. However, the multifractality of the ventricular epicardial electrograms was useful for classifying the recoverability of ischemic tissue. Myocardial ischemia significantly influenced the multifractality of ventricular electrical activity. Recoverability of ischemic myocardium can be classified using the multifractality of ventricular epicardial electrograms. The location and size of regions of severe ischemic myocardium with poor recoverability is detectable using these methods.

Animals↗

PubMed2006

Improved conditions for global exponential stability of recurrent neural networks with time-varying delays.

This paper presents new theoretical results on global exponential stability of recurrent neural networks with bounded activation functions and time-varying delays. The stability conditions depend on external inputs, connection weights, and time delays of recurrent neural networks. Using these results, the global exponential stability of recurrent neural networks can be derived, and the estimated location of the equilibrium point can be obtained. As typical representatives, the Hopfield neural network (HNN) and the cellular neural network (CNN) are examined in detail.

Algorithms↗

PubMed2006

Multiperiodicity of discrete-time delayed neural networks evoked by periodic external inputs.

In this paper, the multiperiodicity of a general class of discrete-time delayed neural networks (DTDNNs) is formulated and studied. Several sufficient conditions are obtained to ensure n-neuron DTDNNs can have 2n periodic orbits and these periodic orbits are locally attractive. In addition, we give the conditions for a periodic orbit to be locally or globally attractive when the periodic orbit locates in a designated region. As two typical representatives, the Hopfield neural network and the cellular neural network are examined in detail. These conditions improve and extend the existing stability results in the literature. Simulations results are also discussed in three illustrative examples.

Algorithms↗

PubMed2006

Solving pseudomonotone variational inequalities and pseudoconvex optimization problems using the projection neural network.

In recent years, a recurrent neural network called projection neural network was proposed for solving monotone variational inequalities and related convex optimization problems. In this paper, we show that the projection neural network can also be used to solve pseudomonotone variational inequalities and related pseudoconvex optimization problems. Under various pseudomonotonicity conditions and other conditions, the projection neural network is proved to be stable in the sense of Lyapunov and globally convergent, globally asymptotically stable, and globally exponentially stable. Since monotonicity is a special case of pseudomononicity, the projection neural network can be applied to solve a broader class of constrained optimization problems related to variational inequalities. Moreover, a new concept, called componentwise pseudomononicity, different from pseudomononicity in general, is introduced. Under this new concept, two stability results of the projection neural network for solving variational inequalities are also obtained. Finally, numerical examples show the effectiveness and performance of the projection neural network.

Algorithms↗

PubMed2006

A simplified dual neural network for quadratic programming with its KWTA application.

The design, analysis, and application of a new recurrent neural network for quadratic programming, called simplified dual neural network, are discussed. The analysis mainly concentrates on the convergence property and the computational complexity of the neural network. The simplified dual neural network is shown to be globally convergent to the exact optimal solution. The complexity of the neural network architecture is reduced with the number of neurons equal to the number of inequality constraints. Its application to k-winners-take-all (KWTA) operation is discussed to demonstrate how to solve problems with this neural network.

Algorithms↗

PubMed2006

Intravenous transplantation of mesenchymal stem cells improves cardiac performance after acute myocardial ischemia in female rats.

Mesenchymal stem cells (MSCs) are potential sources of cells for tissue repairing. However, little information is available regarding the therapeutic potency of intravenously transplanted MSCs for myocardial ischemia (MI). In the present study, MSCs were isolated from bone marrow of male rats and expanded in vitro. Three hours after ligation of left anterior descending artery, the transplanted group received an infusion of MSCs through the tail vein. At the same time, a coronary-ligated control group was injected with culture medium. Homing of MSCs to the heart was assessed by expression of the Y chromosome sry gene using fluorescent in situ hybridization (FISH). At 1 week or 8 weeks after transplantation, sry positive cells were present in cardiac tissue in the transplanted group, but not in the hearts of control group. Cardiomyocytes, smooth muscle cells, and endothelial cells that bore sry gene were identified in transplanted group at 8 weeks after transplantation. Ultrastructural observation revealed that a large number of capillary and some immature myocytes were found to survive in the ischemia region. MSCs transplantation also decreased LVEDP pressure and -dP/dt, but increased LVSP and +dP/dt. The cardiac infarct size was significantly smaller in transplanted group than in control group. Our data suggest that intravenously transplanted MSCs improve cardiac performance and promote the regeneration of blood vessels and cardiomyocytes.

Acute Disease↗

PubMed2006

Conserved residues in juxtamembrane region of the extracellular domain of nicastrin are essential for gamma-secretase complex formation.

The Alzheimer's disease-linked protein, presenilin, forms the active site of the gamma-secretase enzyme complex. However, three other proteins, nicastrin (NCT), PEN-2 and APH-1, are required for enzyme activity. This complex is responsible for cleaving the beta-amyloid precursor protein to produce amyloid beta and the intracellular domain (AICD). Although much research has focused on the regions of presenilin that are important for gamma-secretase function, less is known about NCT. To further our understanding of the role of NCT in gamma-secretase activity and complex formation, we have undertaken a systematic evaluation of conserved residues in the juxtamembrane region of the extracellular domain of NCT. Two mutants, S632A and W648A, greatly reduce gamma-secretase activity, as seen by a reduction in amyloid beta and AICD levels. Several lines of evidence suggest that these mutations result in reduced gamma-secretase activity because they affect the ability of NCT to stably associate with the other gamma-secretase components. Since NCT and APH-1 must first bind in order for presenilin and PEN-2 to stably join the complex, we propose that S632 and W648 are essential for a stable interaction with APH-1.

Amyloid Precursor Protein Secretases↗

PubMed2006

Rapid induction of apoptosis in gastrulating mouse embryos by ethanol and its prevention by HB-EGF.

BACKGROUND: Ethanol exposure during gastrulation and early neurulation induces apoptosis within certain embryonic cell populations, leading to craniofacial and neurological defects. There is currently little information about the initial kinetics of ethanol-induced apoptosis, and interest in the ability of endogenous survival factors to moderate apoptosis is growing. Ethanol alters intracellular signaling, leading to cell death in chick embryos, suggesting that apoptosis could occur rapidly and that signaling pathways activated by survival factors might reduce apoptosis. METHODS: Pregnant mice were intubated with 1, 2, or 4 g/kg ethanol on day 7.5 of embryogenesis (E7.5) 1, 3, or 6, hours before harvesting gastrulation-stage embryos. Control animals received maltose/dextran. Blood alcohol concentrations (BAC) were determined by gas chromatography. E7.5 embryos isolated from untreated dams were cultured in vitro for 1 or 3 hr with 0 or 400 mg% ethanol and 0 or 5 nM heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF). Apoptosis was quantified using fluorescence microscopy to detect annexin V binding and DNA fragmentation [terminal deoxynucleotidyl transferase-mediated dUTP-X nick end labeling (TUNEL)] in whole-mount or sectioned embryos. RESULTS: Both annexin V binding and TUNEL were elevated (p < 0.05) in embryos exposed in utero to 1 g/kg ethanol for 3 hours, increasing linearly with time and ethanol concentration. Apoptosis increased (p < 0.05) in all germ cell layers. Mice treated with 4 g/kg sustained BAC of 400 mg% for nearly 3 hours, significantly increasing apoptosis within the first hour. Cultured embryos exposed to 400 mg% ethanol displayed 2- to 3-fold more TUNEL than vehicle-treated embryos (p < 0.05); however, exogenous HB-EGF prevented apoptosis. CONCLUSIONS: Ethanol rapidly produced apoptosis in gastrulation-stage embryos, consistent with induction by intracellular signaling. The ethanol-induced apoptotic pathway was blocked by the endogenous survival factor, HB-EGF. Differences in the expression of survival factors within individual embryos could be partly responsible for variations in the teratogenic effects of ethanol among offspring exposed prenatally.

Animals↗

PubMed2006

Expression of a laccase cDNA from Trametes sp. AH28-2 in Pichia pastoris and mutagenesis of transformants by nitrogen ion implantation.

A laccase cDNA from Trametes sp. AH28-2 was expressed in Pichia pastoris, with the highest expression level of 4.0 mg L-1 (1360 U mg-1). The apparent Km (24.6 microM) for ABTS (2,2'-azinobis [3-ethylbenzothia-zoline-6-sulfonic acid]) and the carbohydrate content of the recombinant laccase A (rLacA) are approximately identical to those of the native LacA (nLacA). However, the two enzymes differed in the pH optimum when both ABTS and guaiacol served as substrates. The optimum pH for enzyme stability is 5.5 for rLacA. Thermal stability was also investigated. The mutagenesis of rLacA utilizing low-energy nitrogen ion implantation resulted in the isolation of a yeast clone that produced 7.7 mg L-1 (1085 U mg-1) of laccase, 92.5% more than the nonirradiated control (4.0 mg L-1). Compared with rLacA, the mutant LacA (mLacA) with five amino-acid residue changes in the coding sequence showed a slight change in its catalytic ability but superior thermal stability.

Cloning, Molecular↗

PubMed2006

The antimalarial artemisinin synergizes with antibiotics to protect against lethal live Escherichia coli challenge by decreasing proinflammatory cytokine release.

In the present study artemisinin (ART) was found to have potent anti-inflammatory effects in animal models of sepsis induced by CpG-containing oligodeoxy-nucleotides (CpG ODN), lipopolysaccharide (LPS), heat-killed Escherichia coli 35218 or live E. coli. Furthermore, we found that ART protected mice from a lethal challenge by CpG ODN, LPS, or heat-killed E. coli in a dose-dependent manner and that the protection was related to a reduction in serum tumor necrosis factor alpha (TNF-alpha). More significantly, the administration of ART together with ampicillin or unasyn (a complex of ampicillin and sulbactam) decreased mortality from 100 to 66.7% or 33.3%, respectively, in mice subjected to a lethal live E. coli challenge. Together with the observation that ART alone does not inhibit bacterial growth, this result suggests that ART protection is achieved as a result of its anti-inflammatory activity rather than an antimicrobial effect. In RAW264.7 cells, pretreatment with ART potently inhibited TNF-alpha and interleukin-6 release induced by CpG ODN, LPS, or heat-killed E. coli in a dose- and time-dependent manner. Experiments utilizing affinity sensor technology revealed no direct binding of ART with CpG ODN or LPS. Flow cytometry further showed that ART did not alter binding of CpG ODN to cell surfaces or the internalization of CpG ODN. In addition, upregulated levels of TLR9 and TLR4 mRNA were not attenuated by ART treatment. ART treatment did, however, block the NF-kappaB activation induced by CpG ODN, LPS, or heat-killed E. coli. These findings provide compelling evidence that ART may be an important potential drug for sepsis treatment.

Animals↗

PubMed2006

Discovery of FabH/FabF inhibitors from natural products.

Condensing enzymes are essential in type II fatty acid synthesis and are promising targets for antibacterial drug discovery. Recently, a new approach using a xylose-inducible plasmid to express antisense RNA in Staphylococcus aureus has been described; however, the actual mechanism was not delineated. In this paper, the mechanism of decreased target protein production by expression of antisense RNA was investigated using Northern blotting. This revealed that the antisense RNA acts posttranscriptionally by targeting mRNA, leading to 5' mRNA degradation. Using this technology, a two-plate assay was developed in order to identify FabF/FabH target-specific cell-permeable inhibitors by screening of natural product extracts. Over 250,000 natural product fermentation broths were screened and then confirmed in biochemical assays, yielding a hit rate of 0.1%. All known natural product FabH and FabF inhibitors, including cerulenin, thiolactomycin, thiotetromycin, and Tü3010, were discovered using this whole-cell mechanism-based screening approach. Phomallenic acids, which are new inhibitors of FabF, were also discovered. These new inhibitors exhibited target selectivity in the gel elongation assay and in the whole-cell-based two-plate assay. Phomallenic acid C showed good antibacterial activity, about 20-fold better than that of thiolactomycin and cerulenin, against S. aureus. It exhibited a spectrum of antibacterial activity against clinically important pathogens including methicillin-resistant Staphylococcus aureus, Bacillus subtilis, and Haemophilus influenzae.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗

PubMed2006

Multiperiodicity and exponential attractivity evoked by periodic external inputs in delayed cellular neural networks.

We show that an n-neuron cellular neural network with time-varying delay can have 2(n) periodic orbits located in saturation regions and these periodic orbits are locally exponentially attractive. In addition, we give some conditions for ascertaining periodic orbits to be locally or globally exponentially attractive and allow them to locate in any designated region. As a special case of exponential periodicity, exponential stability of delayed cellular neural networks is also characterized. These conditions improve and extend the existing results in the literature. To illustrate and compare the results, simulation results are discussed in three numerical examples.

Models, Neurological↗

PubMed2006

Distribution of WDR36 DNA sequence variants in patients with primary open-angle glaucoma.

PURPOSE: To determine the distribution of WDR36 sequence variants in a cohort of patients with primary open-angle glaucoma (POAG) in the United States. METHODS: All of the 23 coding exons and flanking introns of the WDR36 gene were sequenced in 118 probands from families with at least two members affected by POAG, 6 probands from juvenile-onset POAG families, and 108 control individuals. RESULTS: Thirty-two WDR36 sequence variants were found in this population of patients with POAG. Nonsynonymous single-nucleotide polymorphisms (SNPs), including those previously described as "disease-causing" and "disease susceptibility," were found in 17% of POAG patients and 4% of control subjects. Although the distribution of WDR36 variants in the pedigrees did not show consistent segregation with the disease, the WDR36 sequence variants were found more frequently in patients with more severe disease. CONCLUSIONS: The results of this study suggest that abnormalities in WDR36 alone are not sufficient to cause POAG. The association of WDR36 sequence variants with more severe disease in affected individuals suggests that defects in the WDR36 gene can contribute to POAG and that WDR36 may be a glaucoma modifier gene.

Adult↗

PubMed2006

Studies on vibration characteristics of a pear using finite element method.

The variation of the vibration characteristics of a Huanghua pear was investigated using finite element simulations. A new image processing technique was used to obtain the unsymmetrical and un-spherical geometrical model of a pear. The vibration characteristics of this type of pear with the correlation of its behavior with geometrical configurations and material characteristics were investigated using numerical modal analysis. The results showed that the eigenfrequency increased with the increasing pear Young's modulus, while decreased with increasing pear density, and decreased with increasing pear volume. The results of this study provided foundation for further investigations of the physical characteristics of fruits and vegetables by using finite element simulations.

Computer Simulation↗

PubMed2006

Design and synthesis of novel chemokine analogs derived from vMIP-II.

Stepwise solid phase synthesis using the Fmoc chemistry is reported for a panel of 71-residue and novel unnatural chemokine analogs derived from vMIP-II. This demonstrates the feasibility of using this synthetic method to generate de novo designed protein ligand molecules to study the biology and pharmacology of chemokine receptors.

Amino Acid Sequence↗

PubMed2006

Recognition of protein coding genes in the yeast genome based on the relative-entropy of DNA.

In this paper, a new protein coding gene-finding algorithm specific for the yeast genome at 96% accuracy is proposed. Five-fold cross-validation tests are performed to confirm the above accuracy. By the new algorithm, the number of protein coding genes in the yeast genome is re-estimated. The estimate is based on the assumption that the unknown genes have similar statistical properties to the known genes. It is found that the number of protein coding genes in the 16 yeast chromosomes is less than or equal to 5,873, significantly coincident with the widely accepted range 5,800-6,000.

Algorithms↗