Search PubMed⌕ Search

Biomedical subjects

W Zhang

Publications and source records attributed to W Zhang.

At least 73 records · Page 4Linked to original sources
PubMed2005

Microsatellite markers associated with resistance to Marek's disease in commercial layer chickens.

The objective of the current study was to identify QTL conferring resistance to Marek's disease (MD) in commercial layer chickens. To generate the resource population, 2 partially inbred lines that differed in MD-caused mortality were intermated to produce 5 backcross families. Vaccinated chicks were challenged with very virulent plus (vv+) MD virus strain 648A at 6 d and monitored for MD symptoms. A recent field isolate of the MD virus was used because the lines were resistant to commonly used older laboratory strains. Selective genotyping was employed using 81 microsatellites selected based on prior results with selective DNA pooling. Linear regression and Cox proportional hazard models were used to detect associations between marker genotypes and survival. Significance thresholds were validated by simulation. Seven and 6 markers were significant based on proportion of false positive and false discovery rate thresholds less than 0.2, respectively. Seventeen markers were associated with MD survival considering a comparison-wise error rate of 0.10, which is about twice the number expected by chance, indicating that at least some of the associations represent true effects. Thus, the present study shows that loci affecting MD resistance can be mapped in commercial layer lines. More comprehensive studies are under way to confirm and extend these results.

Animals↗
PubMed2005

Genetic analysis on the direct response to divergent selection for phytate phosphorus bioavailability in a randombred chicken population.

The current study was undertaken to evaluate the direct response to 3 generations of divergent selection for phytate P bioavailability (PBA) in the Athens-Canadian randombred chicken population. Cumulated divergent response (R(C)) was measured as the line difference in PBA at a given generation after adjusting for hatch and sex effects. Results showed a significant response at generation (G)1. The R(C) was unchanged from G1 to G2 and increased (1.62%) from G2 to G3 (P < 0.01) due to the application of best linear unbiased prediction (BLUP) selection in the line selected for high PBA at G2. The average BLUP estimated breeding values were used to estimate the genetic trend for the selected trait across generations. The results showed that the genetic trend was symmetric at G1 and G2 but asymmetric at G3. The application of mixed model methodology was effective in separating the environmental component from phenotypic change. When the data of the high (H) line or the low (L) line in the selected generations (G1 to G3) were combined with the data from the base population (G0), the heritability estimates for PBA were 0.07 +/- 0.02 and 0.09 +/- 0.02, respectively. The line selected for high PBA showed gain, and the line selected for low PBA showed a decrease in estimated breeding values across the generations. The results demonstrated that modest progress could be obtained by incorporating PBA into selection programs. However, other correlated traits of economic importance need to be evaluated before any decision to incorporate selection of PBA into breeding schemes be initiated.

Animals↗
PubMed2005

Correlated responses to divergent selection for phytate phosphorus bioavailability in a randombred chicken population.

The current study was undertaken to evaluate the correlated responses to 3 generations of divergent selection for phytate phosphorus bioavailability (PBA) in the Athens-Canadian randombred chicken population. The traits studied were BW at 4 wk of age, BW gain (BWG), feed consumption (FC), and feed conversion ratio (FCR) during a period of 3 d. The first evaluation criterion was the cumulated divergent correlated response (CR(C)), which was calculated as the line difference of the least square means of phenotypic values for each trait at a given generation after adjustment for sex and hatch effects. The results showed a consistent correlated response in BW across generations. The CR(C) at generation G3 was 26.8 g (P < 0.01). The chickens in the low PBA line (L line) had higher BW than the high PBA line (H line). The CR(C) for BWG, FC, and FCR were significant (P < 0.05) only at G3. The second evaluation criterion was the average best linear unbiased prediction estimated breeding value (EBV). The results showed asymmetric genetic trends in BW, BWG, and FC, and the correlated responses were mainly due to the genetic changes that occurred in H line because little genetic change occurred in L line across generations. At G3, the line differences of EBV were close to the CR(C) values for all the traits except FCR. This suggested that CR(C) and EBV criteria would tend to be consistent with the increase across generations. However, at G1 and G2, the line differences of the EBV actually deviated from the CR(C) values for BWG and FC. The inconsistency could be attributed to experimental errors and genetic drift that were not accounted by the fixed model for obtaining CR(C).

Animals↗
PubMed2005

Identification of a new HLA-B*56 variant, B*5614.

In this report, the novel allele B*5614 is presented. The allele was identified in a Chinese individual by sequence-based typing. HLA-B*5614 differs from B*5608 by a single nucleotide at position 277G-->C in exon 2. This results in an amino acid change from Gly to Arg at codon 93.

Alleles↗
PubMed2005

Identification of HLA-B*5136 in the Chinese population.

We report here a new HLA-B*5136 allele identified by sequence-based typing in the Chinese population. The new B*5136 allele showed four nucleotides difference with B*5108 at exon 3, which are two point mutations at nucleotide positions 527 T-->A and 583 C-->T, and two substitutions at adjacent nucleotide positions 559 C-->A and 560 T-->C. This results in three amino acid changes from Val to Glu at codon 177, Leu to Thr at codon 187, and His to Tyr at codon 195.

Alleles↗
PubMed2005

Oligonucleotide microarray for HLA-DRB1 genotyping: preparation and clinical evaluation.

In this study, HLA-DRB1 gene was genotyped by using the microarray technique. Oligonucleotide probes were designed based on partial sequences of various genotypes of HLA-DRB1, and were fixed on a silylated slide to form a microarray. The second exon of HLA-DRB1 gene in the extracted genomic DNA samples was amplified and labelled by means of polymerase chain reaction (PCR); then it was hybridized to the microarray. The microarray was scanned, and the result was analysed in order to determine the genotypes of HLA-DRB1 of the tested sample. A total of 1574 of 1592 clinical samples had accordant results of genotypes in either microarray assay or PCR-SSP assay; 8 of 10 samples that had inconsistent results of genotypes were proved to be microarray-assay reliable by confirmation of DNA sequencing. It is concluded that microarray is an alternative reliable method for HLA-DRB1 genotyping.

China↗
PubMed2005

Viremia and nasal and rectal shedding of rotavirus in gnotobiotic pigs inoculated with Wa human rotavirus.

Respiratory symptoms with rotavirus shedding in nasopharyngeal secretions have been reported in children with and without gastrointestinal symptoms (Zheng et al., 1991, J. Med. Virol. 34:29-37). To investigate if attenuated and virulent human rotavirus (HRV) strains cause upper respiratory tract infections or viremia in gnotobiotic pigs, we inoculated them with attenuated or virulent HRV intranasally, intravenously, or orally or via feeding tube (gavage) and assayed virus shedding. After oral or intranasal inoculation with attenuated HRV, the pigs remained asymptomatic, but 79 to 95% shed virus nasally and 5 to 17% shed virus rectally. After inoculation by gavage, no pigs shed virus nasally or rectally, but all pigs seroconverted with antibodies to HRV. No viremia was detected through postinoculation day 10. Controls inoculated intranasally with nonreplicating rotavirus-like particles or mock inoculated did not shed virus. In contrast, 100% of pigs inoculated with virulent HRV (oral, intranasal, or gavage) developed diarrhea, shed virus nasally and rectally, and had viremia. The infectivity of sera from the viremic virulent HRV-inoculated pigs was confirmed by inoculating gnotobiotic pigs orally with pooled HRV-positive serum. Serum-inoculated pigs developed diarrhea and fecal and nasal virus shedding and seroconverted with serum and intestinal HRV antibodies. Pigs inoculated intravenously with serum or intestinal contents from the viremic virulent HRV-inoculated pigs developed diarrhea, virus shedding, and viremia, similar to the orally inoculated pigs. This study provides new evidence that virulent HRV causes transient viremia and upper respiratory tract infection in addition to gastrointestinal infection in gnotobiotic pigs, confirming previous reports of rotavirus antigenemia (Blutt et al., Lancet 362:1445-1449, 2003). Our data also suggest that intestinal infection might be initiated from the basolateral side of the epithelial cells via viremia. Additionally, virus shedding patterns indicate a different pathogenesis for attenuated versus virulent HRV.

Animals↗
PubMed2005

Aerobic walking or strengthening exercise for osteoarthritis of the knee? A systematic review.

OBJECTIVE: To compare the efficacy of aerobic walking and home based quadriceps strengthening exercises in patients with knee osteoarthritis. METHODS: The Medline, Pubmed, EMBASE, CINAHL, and PEDro databases and the Cochrane controlled trials register were searched for randomised controlled trials (RCTs) of subjects with knee osteoarthritis comparing aerobic walking or home based quadriceps strengthening exercise with a non-exercise control group. Methodological quality of retrieved RCTs was assessed. Outcome data were abstracted for pain and self reported disability and the effect size calculated for each outcome. RCTs were grouped according to exercise mode and the data pooled using both fixed and random effects models. RESULTS: 35 RCTs were identified, 13 of which met inclusion criteria and provided data suitable for further analysis. Pooled effect sizes for pain were 0.52 for aerobic walking and 0.39 for quadriceps strengthening. For self reported disability, pooled effect sizes were 0.46 for aerobic walking and 0.32 for quadriceps strengthening. CONCLUSIONS: Both aerobic walking and home based quadriceps strengthening exercise reduce pain and disability from knee osteoarthritis but no difference between them was found on indirect comparison.

Disability Evaluation↗
PubMed2005

Non-specific tolerance induced by staphylococcal enterotoxin B in treating high risk corneal transplantation in rats.

AIMS: To explore the role of staphylococcal enterotoxin B (SEB) in treating high risk corneal keratoplasty in rats. METHODS: Rat corneal high risk transplantation rejection models were set up using Fisher 344 and Lewis rats. The experimental rats were injected intraperitoneally with 0.2 ml SEB at different concentrations before keratoplasty. The rejection indexes of the allograft were recorded and the lymphocyte infiltration in the allograft and the percentage of the lymphocyte subpopulation in the lymphatic organs were also examined. Lymphocyte proliferation ability and the concentration of IL-2 and IL-10 in the serum were also evaluated. RESULTS: Compared with the control group, SEB prolonged the survival time of the allograft significantly from 7 to 12 days. It could also reduce CD4(+) and CD8(+) lymphocyte infiltration in the allograft and minimise the percentage of CD4(+) and CD8(+) lymphocytes in the lymphatic organs. The lymphocyte proliferation ability was also weakened. However, the percentage of CD4(+) NK T lymphocytes in the lymphatic organs was raised. The serum concentration of IL-10 was higher but IL-2 was lower in the SEB treated groups. CONCLUSIONS: SEB prolonged the survival time of the allograft in high risk rat corneal allo-transplantation, which may be caused by T cell deletion and acquisition of non-specific tolerance.

Animals↗
PubMed2005

The signaling network of tumor invasion.

The ability of a cell to invade its surroundings is an important hallmark of malignant tumors and results from aberrant cell signaling mechanisms. The signal transduction that leads to tumor invasion can be broken down into major pathways. Even though the pathway systems are distinct in themselves, none of these pathways operate independently when it comes to transmitting signals that culminate in an invasive phenotype. That is, the malignant change in one receptor not only leads to malignant changes directly downstream but can also affect the molecules of many other pathways. Three major pathway systems involved in tumor invasion are discussed in this review: the integrin system, the insulin-like growth factor system, and the Rho family GTPases. Here we see that although the individual signaling systems can each contribute to invasion, each system is networked to others and should not be considered isolated. Each system is first reviewed as independent contributors to an invasive phenotype and then discussed in the context of interacting pathways that collectively result in tumor invasion.

Animals↗
PubMed2005

A single-gene biomarker identifies breast cancers associated with immature cell type and short duration of prior breastfeeding.

The pathogenesis of breast cancers that do not express estrogen receptors or Her-2/neu receptors (ER-/HER2- phenotype) is incompletely understood. We had observed markedly elevated gene expression of gamma-aminobutyric acid type A (GABA(A)) receptor subunit pi (GABApi, GABRP) in some breast cancers with ER-/HER2- phenotype. In this study, transcriptional profiles (TxPs) were obtained from 82 primary invasive breast cancers by oligonucleotide microarrays. Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to measure GABApi gene expression in a separate cohort of 121 invasive breast cancers. GABApi gene expression values from TxP and RT-PCR were standardized and compared with clinicopathologic characteristics in the 203 patients. GABApi gene expression was increased in 16% of breast cancers (13/82 TxP, 20/ 121 RT-PCR), particularly in breast cancers with ER-/HER2- phenotype (60%), and breast cancers with basal-like genomic profile (60%). The profile of genes coexpressed with GABApi in these tumors was consistent with an immature cell type. In multivariate linear regression analysis, the level of GABApi gene expression was associated with ER-/HER2- phenotype (P < 0.0001), younger age at diagnosis (P = 0.0003), and shorter lifetime duration of breastfeeding (< or = 6 months) in all women (P = 0.017) and specifically in parous women (P = 0.013). GABApi gene expression was also associated with combinations of high grade with ER-/HER2- phenotype (P = 0.002), and with Hispanic ethnicity (P = 0.036). GABApi gene expression is increased in breast cancers of immature (undifferentiated) cell type and is significantly associated with shorter lifetime history of breastfeeding and with high-grade breast cancer in Hispanic women.

Biomarkers, Tumor↗
PubMed2005

Successful resuscitation after carbon dioxide embolism during laparoscopic-assisted abdomino-perineal resection.

We report a 67-year-old woman who underwent laparoscopic-assisted abdomino-perineal resection for rectal carcinoma. She sustained hypotension of 40/20 mmHg associated with bradycardia (heart rate 30 to 45 beats per minute) and an end-tidal carbon dioxide level of zero when she was raised to a head-up position at the end of surgery to facilitate pelvic irrigation. Pulmonary air embolism was confirmed by aspiration of 15 millilitres of foamy blood from her central venous line. Resuscitation was successful and she recovered completely with no neurological deficits.

Aged↗
PubMed2005

Anaerobic bio-hydrogen production using pre-heated river sediments as seed sludge.

Anaerobic bio-hydrogen production is the focus in the field of bio-energy resources. In this paper, a series of batch experiments were conducted to investigate the effects of several factors on anaerobic bio-hydrogen producing process carried out by pre-heated river sediments. The results showed that several factors such as substrate and its concentration, temperature and the initial pH value could affect the anaerobic bio-hydrogen production in different levels. At 35 degrees C and the initial pH of 6.5, using glucose of 20,000 mg COD/L as substrate, the highest hydrogen production of 323.8 ml-H2/g TVS in a 100 ml batch reactor was reached, the specific hydrogen production rate was 37.7 ml-H2/g TVS h, and the hydrogen content was 51.2%. Thereafter using the same pre-heated river sediments as seed sludge, continuous anaerobic bio-hydrogen production was achieved successfully in a lab-scale CSTR with gas-separator. At the organic loading rate of 36 kg COD/m3 d, the highest hydrogen production was 6.3-6.7 l-H2/l-reactor d, the specific hydrogen production was 1.3-1.4 mol-H2/mol-glucose, and the hydrogen content in the gas was 52.3%. The effluent of the bio-reactor contained some small molecular organics, mainly including ethanol, acetate, butyrate and their molar proportion is 1:1:0.6.

Acetates↗
PubMed2004

Subcellular vesicular aggregations of GABAB R1a and R1b receptors increase with age in neurons of the developing mouse brain.

GABA(B) receptors play a critical neuromodulatory role in the central nervous system. It has been suggested that both the functional role and the cellular distribution of GABA(B) receptors in the neuronal network change during post-natal maturation. In the present study, the cellular and subcellular distribution patterns of the GABA(B) R1a/b receptors have been analysed in different brain regions of the mouse using immunocytochemistry with isoform-specific antisera. GABA(B) R1-immunoreactivity (IR) was present from the first post-natal day (P0) on in most regions of the brain. Neurones exhibited diffuse GABA(B) R1-IR labelling throughout somata and larger proximal dendrites as well as some fine neuronal processes. After P5, distinct punctuated staining was apparent. The number of such GABA(B) IR granules per cell increased with age in a sigmoidal manner from P5 to P60. Electron microscopy revealed GABA(B) IR as clusters of small clear vesicles of 30-50 nm diameter within the cytoplasm and close to the cell membrane at extrasynaptic locations, as well as at pre-synaptic and post-synaptic specialisations. The increase in GABA(B) R1-IR punctuate staining during brain maturation points to increasing functional participation and heterogeneity of GABA(B) receptors as the complexity of the central nervous system expands with growth and development.

Aging↗
PubMed2004

Chinese herbal medicine for atopic eczema.

BACKGROUND: Traditional Chinese herbal mixtures have been used to treat atopic eczema for many years. Their efficacy has attracted public attention and recently some clinical trials have been undertaken. OBJECTIVES: To assess the effects of Chinese herbal mixtures in the treatment of atopic eczema. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) ( January 2004), the Cochrane Skin Group Specialised Register (January 2004), MEDLINE (1966 to January 2004), EMBASE (1980 to January 2004), CINHL (1980 to January 2004) and a number of complementary medicine databases. In addition, the cited references of all trials identified and key review articles were searched. Pharmaceutical companies involved in oral traditional Chinese herbs and experts in the field were contacted. SELECTION CRITERIA: Randomised controlled trials of Chinese herbal mixtures used in the treatment of atopic eczema. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied eligibility criteria, assessed the quality of the trials and extracted data. Any discrepancies were discussed to achieve consensus. MAIN RESULTS: Four randomised controlled trials, with eight weeks for each phase, met the inclusion criteria. The trials randomised 159 participants aged from 1 to 60 years. The withdrawal rates ranged from 7.5% to 22.5% and no trial used intention to treat analysis. Three trials were randomised placebo controlled, two-phase cross-over designs assessing the same Chinese herbal mixture, Zemaphyte. In two of these three trials the reduction in erythema and surface damage was greater on Zemaphyte than on placebo, and participants slept better and itched less and expressed a preference for Zemaphyte. The fourth trial was an open-label design comparing Zemaphyte in herbal form with Zemaphyte as a freeze dried preparation. There was a reduction in erythema and surface damage with both formulations, but no comparison between the two formulations was reported. Some adverse effects were reported in all four trials, but none were regarded as serious. REVIEWERS' CONCLUSIONS: Chinese herbal mixtures may be effective in the treatment of atopic eczema. However, only four small poorly reported RCTs of the same product, Zemaphyte, were found and the results were heterogeneous. Further well-designed, larger scale trials are required, but Zemaphyte is no longer being manufactured.

Dermatitis, Atopic↗