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Biomedical subjects

K Wang

Publications and source records attributed to K Wang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Reproducibility of the masseteric exteroceptive suppression period using stimulus-response curves.

The present study evaluated the reproducibility of the late exteroceptive suppression period (ES2) and of pain perception. The surface electro-myogram (EMG) was recorded from the left masseter muscle in 12 males and 12 females (22-31 year). Thirteen fixed stimulus intensities from 5 to 25 mA with 2.5 mA intervals were applied at random to the left mental area, and stimulus-response (S-R) curves were built for each subject. The first stimulation intensity at which the ES2 appeared was defined the reflex threshold, while the lowest stimulus intensity the subjects scored as painful, was called the pain threshold. Using the S-R curves, the other reflex parameters (appearance level, saturation level, slope from appearance to saturation, maximum duration of ES2, and maximum suppression degree) were also determined. Two measurement sessions were scheduled. Both the reflex and the pain sensation appeared at significantly lower stimulus intensity in females than males (P < 0.05). The reflex threshold, the reflex appearance and saturation level showed a significant decrease from the first to second session (P < 0.05), while the pain threshold was significantly higher during the second session (P < 0.01). By contrast, a good reproducibility was found for the maximum duration and suppression degree of ES2. Consequently, if S-R curves would be used to study the relation between the ES2 parameters and stimulus intensity in normal subjects for their applicability in clinical conditions, maximum duration and maximum suppression degree should be focused upon, in order to avoid session and gender effects as confounding factors.

Adult↗
PubMed2006

Quantitative-trait-locus mapping in the presence of locus heterogeneity.

Locus heterogeneity is a concern for quantitative trait locus mapping where phenotypes are likely to be influenced by more than one gene. We introduce a model which generalizes the locus heterogeneity model of Smith (1961) from dichotomous traits to quantitative traits and consider some test statistics for this model. The type I error rates and the power of these statistics are assessed through simulation studies. These statistics are applied to a linkage study of asthma genes.

Asthma↗
PubMed2006

Evaluation of Dicyphus hersperus (Heteroptera: Miridae) for biological control of Frankliniella occidentalis (Thysanoptera: Thripidae) on greenhouse tomato.

The effectiveness of inoculative releases of the mirid predator Dicyphus hesperus Knight for control of Frankliniella occidentalis (Pergande) on greenhouse tomatoes was evaluated in terms of suppression of the population densities of F. occidentalis and associated fruit damage in the presence of the predator over two seasonal trials. An inoculative release of one D. hesperus per plant (approximately 0.1:10 predator:prey ratio) at a high F. occidentalis population density (140 thrips per plant) suppressed the thrips population density to a significantly lower level, compared with the nonrelease greenhouse, but not below a thrips level that caused economic fruit damage. As the predator:prey ratio increased to approximately 0.5:10 D. hesperus:F. occidentalis, the mean percentage of the thrips-damaged fruit in the D. hesperus release greenhouse decreased to 1.6%. However, the amount of fruit feeding by D. hesperus was highly correlated to the availability of prey (or predator:prey ratio) under greenhouse conditions. D. hesperus-induced fruit damage occurred when the predator:prey ratio was >1:10 D. hesperus:F. occidentalis. Considering the potential risk of fruit damage by D. hesperus and the need for effective control of F. occidentalis, a 0.5-1:10 D. hesperus:F. occidentalis ratio is recommended when the thrips population density is in the range of 60-150 thrips per plant.

Animals↗
PubMed2006

[Phenotype of peripheral blood mononuclear cells derived dendritic cells from patients with chronic hepatitis B.].

BACKGROUND: The aim of this study was to access phenotype changes of dendritic cells (DC) cultured from peripheral blood mononuclear cells (PBMC) in patients with chronic hepatitis B and to reveal the relationship between phenotype of DC and ALT or HBV DNA. METHODS: Indices of ALT and serum HBV DNA were measured in 37 patients with chronic hepatitis B and 21 healthy controls. Peripheral blood mononuclear cells were isolated from all patients and healthy controls, and cultured with granulocyte-macrophage colony-stumilating factor (GM-CSF), interleukin-4 (IL-4) and tumor necrosis factor- (TNF-)in RPMI 1640 medium that contained 10% fetal calf serum. After culturing for 7 days, the DC was counted and the phenotypes were detected by FACS. Then the data were statistically analysed. RESULTS: The DC was significantly fewer (P less than 0.05) in patients with chronic hepatitis B than the controls. In particular, the expressive level of CD83 and CD86 on DC's surface from patients with chronic hepatitis B were also significantly lower (P less than 0.05) than that from the controls. In the patients with hepatitis B, the indices of DC had a significantly negative correlation with the level of serum HBV DNA (P less than 0.05), but no significant relationship was found between ALT and indices of DC (P greater than 0.05). CONCLUSION: The DC cultured from patients with chronic hepatitis B were few and had immature phenotype. These changes had a significantly negative correlation with the level of serum HBV DNA, but had not correlation with the inflammatory reaction levels in the liver. DC was associated with the clearance of HBV in patients with hepatitis B.

Animals↗
PubMed2005

Effects of masticatory muscle fatigue without and with experimental pain on jaw-stretch reflexes in healthy men and women.

OBJECTIVE: To examine the effects of experimentally evoked masticatory muscle fatigue, without and with experimental muscle pain, on the short-latency jaw-stretch reflex, using a randomised crossover design. METHODS: Reflexes were evoked in both the masseter and temporalis muscles in 15 men and 13 women. The study was performed in two blocks, both containing 3 experimental conditions (before, directly after, and 15 min after provocation). Provocation consisted of a fatiguing chewing test, followed by an intramuscular injection of either isotonic saline (IS; non-painful) or hypertonic saline (HS; painful). RESULTS: No significant effects of the experimental condition 'fatigue+IS' were found for any of the reflex outcome variables. For each muscle, the 'fatigue+HS' condition yielded significantly higher normalized reflex amplitudes than the other conditions. Several muscles displayed gender differences regarding both onset latency and normalized reflex amplitude. CONCLUSIONS: Experimentally evoked mild-to-moderate muscle fatigue does not modulate the human jaw-stretch reflex. On the other hand, experimental muscle pain, evoked after the performance of a fatiguing chewing test, does yield a facilitation of this reflex. The gender differences found in both onset latency and peak-to-peak amplitude stress the need to take gender into consideration in future jaw reflex studies. SIGNIFICANCE: The sensitivity of the human jaw-stretch reflex can be modulated by HS-induced muscle pain; not by muscle fatigue that is provoked by intense chewing.

Adult↗
PubMed2005

Tumor necrosis factor alpha (TNF-alpha) coordinately regulates the expression of specific matrix metalloproteinases (MMPS) and angiogenic factors during fracture healing.

Recent studies from our laboratory demonstrate that TNF-alpha signaling contributes to the regulation of chondrocyte apoptosis and a lack of TNF-alpha signaling leads to a persistence of cartilaginous callus and delayed resorption of mineralized cartilage. This study examines how delays in the endochondral repair process affect the expression of specific mediators of proteolytic cartilage turnover and vascularization. Simple closed fractures were produced in wild type and TNF-alpha receptor (p55-/-/p75-/-)-deficient mice. Using ribonuclease protection assay (RPA) and microarray analysis, the expression of multiple mRNAs for various angiogenic factors and the metalloproteinase gene family were measured in fracture calluses. The direct actions of TNFalpha on the expression of specific angiogenic factors and metalloproteinases (MMPs) was examined in both cultured callus cells and articular chondrocytes to compare the effects of TNF-alpha in growth cartilage versus articular cartilage. MMPs 2, 9, 13, and 14 were quantitatively the most prevalent metalloproteases and all showed peaks in expression during the chondrogenic period. In the absence of TNF-alpha signaling, the expression of all of these mRNAs was reduced. The angiopoietin families of vascular regulators and their receptors were expressed at much higher levels than the VEGFs and their receptors and while the angiopoietins showed diminished or delayed expression in the absence of TNF-alpha signaling, VEGF and its receptors remained unaltered. The expression of vascular endothelial growth inhibitor (VEGI or TNFSF15) showed a near absence in its expression in the TNF-alpha receptor-deficient mice. In vitro assessment of cultured fracture callus cells in comparison to primary articular chondrocytes showed that TNF-alpha treatment specifically induced the expression of MMP9, MMP14, VEGI, and Angiopoietin 2. These results suggest that TNF-alpha signaling in chondrocytes controls vascularization of cartilage through the regulation of angiopoietin and VEGI factors which play counterbalancing roles in the induction of growth arrest, or apoptosis in endothelial cells. Furthermore, TNF-alpha appears to regulate, in part, the expression of two key proteolytic enzymes, MMP 9 and MMP14 that are known to be crucial to the progression of vascularization and turnover of mineralized cartilage. Thus, TNF-alpha signaling in healing fractures appears to coordinate the expression of specific regulators of endothelial cell survival and metalloproteolytic enzymes and is essential in the transition and progression of the endochondral phase of fracture repair.

Angiogenic Proteins↗
PubMed2005

Ramifications of impaired PRPP synthesis in Saccharomyces cerevisiae.

The model eukaryote Saccharomyces cerevisiae is well suited to investigate the causes of metabolic disturbance. PRPP [5-phospho-D-ribosyl-1(alpha)-pyrophosphate] may be regarded as a junction of carbon and nitrogen metabolism. As a result of this central position, perturbations in its synthesis can give rise to many unexpected cellular events, such as impaired cell integrity. We have taken advantage of S. cerevisiae's genetic tractability to investigate the metabolic links responsible for connecting the biochemical intermediate PRPP to apparently unrelated cellular functions. This approach provides insight into the co-ordination of different biological processes.

Molecular Structure↗
PubMed2005

In Saccharomyces cerevisiae, impaired PRPP synthesis is accompanied by valproate and Li+ sensitivity.

The biosynthetic intermediate PRPP (phosphoribosylpyrophosphate) has a central role in cellular biochemistry since it links carbon and nitrogen metabolism. Its importance may be reflected in the fact that, in the Saccharomyces cerevisiae (yeast) genome, there are five unlinked genes, PRS1-PRS5, each of which is theoretically capable of encoding the enzyme synthesizing PRPP. Interference with the complement of PRS genes in S. cerevisiae has far-reaching consequences for yeast physiology and has uncovered unexpected metabolic links including cell wall integrity and phospholipid metabolism.

Binding Sites↗
PubMed2005

Bone scintigraphy in common tumors with osteolytic components.

Osteolytic lesions are frequently encountered in clinical practice. Radionuclide bone scans with technetium-99m-labeled diphosphonates are often performed in the evaluation of both solitary and multiple osteolytic lesions. In this pictorial review, we critically evaluate the current role of bone scan in common osteolytic tumors including aneurysmal bone cyst, simple bone cyst, fibrous dysplasia, nonossifying fibroma, giant cell tumor, eosinophilic granuloma, enchondroma, chondrosarcoma, osteosarcoma, Ewing sarcoma, myeloma, and metastases. The merits and limitations of bone scanning are emphasized.

Aged↗
PubMed2005

Clinical and genetic study on a new Chinese family with benign familial infantile seizures.

Three loci for benign familial infantile seizures (BFIS, traditionally named benign familial infantile convulsions) have been mapped to the chromosome regions of 19q12-13.1, 2q24, and 16p12-q12. We characterized the clinical features of a newly discovered Chinese family with BFIS and investigated whether it is linked to these loci. A four-generation Chinese family was investigated and nineteen family members were examined. Fourteen microsatellite markers covering the three BFIS loci on the chromosome regions of 19q12-13.1, 2q24, and 16p12-q12 were genotyped. Linkage analysis was performed. The main clinical features of our patients include onset of afebrile seizures between 3 and 10 months, normal psychomotor development, normal interictal electroencephalogram (EEG), and autosomal dominant inheritance. Magnetic resonance imaging (MRI) changes were found in the proband. Two-point LOD scores are < -2.0 at the recombination rate of 0.0 for all the markers on the 2q24 region. Multipoint LOD scores are < -3.0 for the regions of 19q12-13.1 and 16p12-q12. Linkage analysis showed no evidence that the disease gene of this BFIS family is linked to the chromosome regions previously identified as the critical regions of the disease. Another chromosome region harboring the disease gene may exist in the new Chinese family.

Adult↗
PubMed2005

A likelihood approach for quantitative-trait-locus mapping with selected pedigrees.

Selective sampling is a cost-effective design for mapping quantitative trait loci (QTLs). A unified framework, which naturally combines two complementary sources of linkage information in the data, is proposed for the mapping of QTLs using selected pedigrees. Score statistics for detecting linkage are introduced for single-locus models (univariate or bivariate phenotypes) and two-locus epistasis models. A computer implementation of the methods for single-locus univariate-phenotype models is provided for nuclear families with arbitrary number of sibs and is freely available.

Algorithms↗
PubMed2005

Effect of ribavirin on intracellular and plasma pharmacokinetics of nucleoside reverse transcriptase inhibitors in patients with human immunodeficiency virus-hepatitis C virus coinfection: results of a randomized clinical study.

The intracellular triphosphorylation and plasma pharmacokinetics of lamivudine (3TC), stavudine (d4T), and zidovudine (ZDV) were assessed in a pharmacokinetic substudy, in 56 human immunodeficiency virus-hepatitis C virus (HIV-HCV) coinfected patients receiving peginterferon alfa-2a (40KD) 180 microg/week plus either placebo or ribavirin (RBV) 800 mg/day in the AIDS PEGASYS Ribavirin International Coinfection Trial. There were no significant differences between patients treated with RBV and placebo in plasma pharmacokinetics parameters for the nucleoside reverse transcriptase inhibitors (NRTIs) at steady state (weeks 8 to 12): ratios of least squares mean of area under the plasma concentration-time curve (AUC(0-12 h)) were 1.17 (95% confidence interval, 0.91 to 1.51) for 3TC, 1.44 (95% confidence interval, 0.58 to 3.60) for d4T and 0.85 (95% confidence interval, 0.50 to 1.45) for ZDV, and ratios of least squares mean plasma C(max) were 1.33 (95% confidence interval, 0.99 to 1.78), 1.06 (95% confidence interval, 0.68 to 1.65), and 0.84 (95% confidence interval, 0.46 to 1.53), respectively. Concentrations of NRTI triphosphate (TP) metabolites in relation to those of the triphosphates of endogenous deoxythymidine-triphosphate (dTTP) and deoxcytidine-triphosphate (dCTP) were similar in the RBV and placebo groups. Differences (RBV to placebo) in least squares mean ratios of AUC(0-12 h) at steady state were 0.274 (95% confidence interval, -0.37 to 0.91) for 3TC-TP:dCTP, 0.009 (95% confidence interval, -0.06 to 0.08) for d4T-TP:dTTP, and -0.081 (95% confidence interval, -0.40 to 0.24) for ZDV-TP:dTTP. RBV did not adversely affect HIV-1 replication. In summary, RBV 800 mg/day administered in combination with peginterferon alfa-2a (40KD) does not significantly affect the intracellular phosphorylation or plasma pharmacokinetics of 3TC, d4T, and ZDV in HIV-HCV-coinfected patients.

Adult↗
PubMed2005

BioMediator data integration: beyond genomics to neuroscience data.

The BioMediator system developed at the University of Washington (UW) provides a theoretical and practical foundation for data integration across diverse biomedical research domains and various data types. In this paper we demonstrate the generalizability of its architecture through its application to the UW Human Brain Project (HBP) for understanding language organization in the brain. We first describe the system architecture and the characteristics of the four data sources developed by the UW HBP. Second we present the process of developing the application prototype for HBP neuroscience researchers posing queries across these semantically and syntactically heterogeneous neurophysiologic data sources. Then we discuss the benefits and potential limitations of the BioMediator system as a general data integration solution for different user groups in genomic and neuroscience research domains.

Brain↗
PubMed2005

A pilot bridging data integration and analytics: BioMediator and R?

Biological research today involves aggregating and analyzing large amounts of data from disparate sources. Tools such as the University of Washington's BioMediator system integrate heterogeneous data. Analytic packages such as the R environment have a rich set of tools to analyze biomedical research data. Our pilot project bridged data integration and analytics in a general way by successfully incorporating the BioMediator system into the R platform for specific analyses on neurophysiologic research data.

Brain↗
PubMed2004

Human hepatitis B virus X protein promotes cell proliferation and inhibits cell apoptosis through interacting with a serine protease Hepsin.

The X protein of human hepatitis B virus (HBV) acts as an indirect transcriptional transactivator to regulate the expression of many viral and cellular genes as well as playing a critical role in the development of hepatocellular carcinoma. While the biological importance of HBx has been well established, the cellular and molecular bases of its function remain largely undefined. In this study, we isolated a new HBV field strain from a patient with chronic viral infection. The X protein encoded by this virus was used as a bait protein for screening a human liver cDNA library using a yeast two-hybrid system. Several cell proteins were identified as new HBx interacting partners, including a transmembrane serine protease, Hepsin. Direct interaction between HBx and Hepsin proteins was confirmed by in vitro and in vivo co-immunoprecipitation assays. HBx also co-localized with Hepsin in human cells as determined by confocal immunofluorescence microscopy. The interaction between HBx and Hepsin protein appeared to play a role in both promoting cell proliferation and blocking apoptosis in human liver tumor cell and normal liver cell lines. In addition, the complex of HBx and Hepsin promoted the expression of HBeAg in Hep G2.2.1.5 cells indicating that the association of these two proteins stimulated viral replication.

Apoptosis↗
PubMed2004

Searches for B0 decays to combinations of two charmless isoscalar mesons.

We search for B meson decays into two-body combinations of eta, eta', omega, and phi mesons from 89 x 10(6) BB pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at SLAC. We find the branching fraction B(B0-->etaomega)=(4.0(+1.3)(-1.2)+/-0.4)x10(-6) with a significance of 4.3 sigma. For the other decay modes we set the following 90% confidence level upper limits on the branching fractions, in units of 10(-6): B(B0-->etaeta)<2.8, B(B0-->etaeta')<4.6, B(B0-->eta'eta')<10, B(B0-->eta'omega)<2.8, B(B0-->etaphi)<1.0, B(B0-->eta'phi)<4.5, and B(B0-->phiphi)<1.5.

Journal Article↗
PubMed2004

Search for B+/--->[K(-/+)pi(+/-)](D)K+/- and upper limit on the b-->u amplitude in B+/--->DK+/-.

We search for B+/--->[K(-/+)pi(+/-)](D)K+/- decays, where [K(-/+)pi(+/-)](D) indicates that the K-/+pi(+/-) pair originates from the decay of a D0 or D (0). Results are based on 120x10(6) Upsilon(4S)-->BB decays collected with the BABAR detector at SLAC. We set an upper limit on the ratio R(Kpi) identical with[Gamma(B+-->[K(-)pi(+)](D)K+)+Gamma(B--->[K(+)pi(-)](D)K-)][Gamma(B+-->[K(+)pi(-)](D) / K+)+Gamma(B--->[K(-)pi(+)](D)K-)]<0.026 (90% C.L.). This constrains the amplitude ratio r(B) identical with|A(B--->D 0K-)/A(B--->D0K-)|<0.22 (90% C.L.), consistent with expectations. The small value of r(B) favored by our analysis suggests that the determination of the Cabibbo-Kobayashi-Maskawa phase gamma from B-->DK will be difficult.

Journal Article↗