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Biomedical subjects

H Yang

Publications and source records attributed to H Yang.

At least 37 records · Page 2Linked to original sources
PubMed2005

Workplace and HIV-related sexual behaviours and perceptions among female migrant workers.

Data from 1,543 female migrants working in eight occupational clusters in Beijing and Nanjing, China were analysed to examine the association of workplace with HIV-related behaviours and perceptions. For sexually experienced women (n = 666, 43.2%), those working in entertainment establishments or personal service (e.g., nightclubs, dancing halls, barbershops, beauty salons, massage parlours, etc.) engaged in risky sexual practices twice as frequently as those working in non-entertainment establishments (e.g. restaurants, stalls, domestic service, factories, etc.). About 10% of women in the entertainment establishments reported having sold sex, 30% having multiple sexual partners and 40% having sex with men with multiple sexual partners. The rate of consistent condom use was less than 15%. They also tended to have a higher level of perceptions of both peer risk involvement and positive expectancy of risk behaviours, and lower perceptions of severity of STDs and HIV. For women who were not sexually experienced, those working in 'stalls' or 'domestic service' tended to perceive higher peer risk involvement, less severity of HIV infection, and less effectiveness of protective behaviour. The occupational pattern of sexual risk behaviours and perceptions observed in the current study indicates employment conditions are associated with HIV risk. Intervention strategies should be tailored to address occupational-related factors.

Adolescent↗
PubMed2005

Ex vivo expansion of umbilical cord blood.

The efficacy of cord blood (CB) transplantation is limited by the low cell dose available. Low cell doses at transplant are correlated with delayed engraftment, prolonged neutropenia and thrombocytopenia and elevated risk of graft failure. To potentially improve the efficacy of CB transplantation, approaches have been taken to increase the cell dose available. One approach is the transplantation of multiple cord units, another the use of ex vivo expansion. Evidence for a functional and phenotypic heterogeneity exists within the HSC population and one concern associated with ex vivo expansion is that the expansion of lower 'quality' hematopoietic progenitor cells (HPC) occurs at the expense of higher 'quality' HPC, thereby impacting the reserve of the graft. There is evidence that this is a valid concern while other evidence suggests that higher quality HPC are preserved and not exhausted. Currently, ex vivo expansion processes include: (1) liquid expansion: CD34+ or CD133+ cells are selected and cultured in medium containing factors targeting the proliferation and self-renewal of primitive hematopoietic progenitors; (2) co-culture expansion: unmanipulated CB cells are cultured with stromal components of the hematopoietic microenvironment, specifically mesenchymal stem cells (MSC), in medium containing growth factors; and (3) continuous perfusion: CB HPC are cultured with growth factors in 'bioreactors' rather than in static cultures. These approaches are discussed. Ultimately, the goal of ex vivo expansion is to increase the available dose of the CB cells responsible for successful engraftment, thereby reducing the time to engraftment and reducing the risk of graft failure.

Cell Culture Techniques↗
PubMed2005

High overall in vitro efficiency of porcine handmade cloning (HMC) combining partial zona digestion and oocyte trisection with sequential culture.

We investigated the in vitro developmental competence of porcine embryos produced from in vitro matured (IVM) oocytes by improved HMC and parthenogenetic activation (PA). Embryos were cultured in a modified North Carolina State University (NCSU37) medium. Firstly, we compared the developmental competence between oocytes from sows and gilts by zona-intact (ZI) and zona-free (ZF) PA. Significantly higher (p < 0.05) blastocyst rates were obtained from sow oocytes (42 +/- 4% for ZF and 55 +/- 6% for ZI) than gilt oocytes (20 +/- 2% for ZF and 26 +/- 5% for ZI). Secondly, sow oocytes were used to establish the modified HMC that was based on a modified enucleation with partial zona digestion and trisection of porcine oocytes and the use of three cytoplasts and one somatic cell for embryo reconstruction. In vitro fertilization (IVF) and in parallel ZF PA were used as the control systems. After oocyte trisection, >90% of oocyte fragments were recovered, resulting in an average of 37 reconstructed embryos from 100 oocytes. Blastocyst rates of HMC, IVF, and ZF PA embryos were 17 +/- 4%, 30 +/- 6%, and 47 +/- 4%, respectively. Our results prove that HMC in pigs may result in high in vitro efficiency up until the blastocyst stage. In vivo developmental competence will be confirmed in embryo transfer experiments.

Animals↗
PubMed2005

Serum immunoglobulins in psoriatic erythroderma.

The cause of psoriatic erythroderma (PE) is still unknown. Elevation of serum IgE has been reported in erythroderma, and as serum hyper-IgE is Th2 cell dominated it is of interest to investigate the serum IgE level in PE. In this study, the level of immunoglobulins in the sera of PE patients was analysed by a retrospective case-control study using psoriasis vulgaris (PV) patients as controls. The PE and PV patients were matched in a 1:3 pattern: the first three age and sex matched PV inpatients were selected. All of the subjects were nonatopic and without allergic history. The serum IgE level was found to be elevated in 81.3% of the PE group, which is much higher than that (6.3%) of the controls (odds ratio, 65.0; 95% CI, 11.7-361.2; P < 0.001; chi2 test). The mean level of serum IgE was much higher in the PE group (272.38 +/- 207.63 IU/mL vs. 53.20 +/- 86.05 IU/mL, P < 0.001, Student's t-test). No differences were found for other immunoglobulins. These results suggest that in PE the Th1/Th2 cell imbalance may be switched from Th1 dominant to Th2 dominant. The exact role of serum IgE in PE should be investigated further.

Adolescent↗
PubMed2005

Activity of adefovir dipivoxil against all patterns of lamivudine-resistant hepatitis B viruses in patients.

One hundred and thirty-one post-liver transplantation patients with chronic hepatitis B and failing lamivudine therapy with detectable serum hepatitis B virus (HBV) deoxyribonucleic acid by hybridization assays or > or =1 x 10(6) copies/mL by polymerase chain reaction, and elevated alanine transaminase levels despite continuous lamivudine, were enrolled in an open-label study of adefovir dipivoxil. The B and C domains of HBV polymerase were sequenced for baseline samples to determine the presence of lamivudine resistance mutations. The results showed that 98% of the samples had tyrosine-methionine-aspartate-aspartate (YMDD) mutations, indicating a strong correlation between the above clinical definition of lamivudine treatment failure and the presence of YMDD mutations. In addition to the rtM204V/I and the rtL180M mutations, the mutation rtV173L was identified in 19% of patients. Four major patterns of lamivudine-resistant HBV were identified: rtL180M + rtM204V (60%), rtV173L + rtL180M + rtM204V (19%), rtM204I (9%) and rtL180M + rtM204I (9%). Treatment with adefovir dipivoxil showed similar antiviral efficacy in patients with lamivudine-resistant virus from all four patterns.

Adenine↗
PubMed2005

Recurrence of symptomatic atrial fibrillation after successful catheter ablation of atrioventricular accessory pathways: a multivariate regression analysis.

The primary aim of this study is to investigate the factors related to the recurrence of atrial fibrillation (AF) after a successful ablation of atrioventricular accessory pathway. Thirty-seven patients with spontaneous AF (study group) were selected from 401 consecutive patients who underwent radiofrequency catheter ablation of atrioventricular accessory pathway. A multivariate regression analysis was used in order to evaluate the relationships between AF recurrence and patients' age, sex, atrial size, left ventricular function, location of accessory pathways, heart rate during atrioventricular re-entrant tachycardia and atrial vulnerability (induction of sustained AF) after a successful ablation. Atrioventricular accessory pathway was abolished in 36 of the study group patients and 351 of the control group patients. During the follow-up of 36 +/- 11 months, four patients (11.1%) from the study group experienced sustained AF. Multivariate regression analysis showed that, in patients with pre-ablation AF, older age and post-ablation atrial vulnerability were the only independent predictive factors for AF recurrence. We concluded that radiofrequency catheter ablation of atrioventricular accessory pathway greatly reduces the risk of AF in patients who had a history of symptomatic AF. Older patients and patients with inducible AF after accessory pathway ablation are at an increased risk of AF recurrence. These patients should be closely monitored after successful ablation of atrioventricular accessory pathways.

Adult↗
PubMed2005

First experience with direct, selective factor Xa inhibition in patients with non-ST-elevation acute coronary syndromes: results of the XaNADU-ACS Trial.

BACKGROUND: Unfractionated heparin is widely used in patients with non-ST-elevation acute coronary syndromes but has important limitations. Anticoagulants with predictable kinetics and anticoagulant effects, better efficacy, and greater safety are needed. OBJECTIVE: To investigate the efficacy and safety of a direct, selective factor Xa inhibitor, DX-9065a (Daiichi Pharmaceuticals LTD, Inc.) compared with heparin, in patients with non-ST-elevation acute coronary syndromes. PATIENTS AND METHODS: Patients (n = 402) from the USA, Canada, and Japan were randomized to blinded, weight-adjusted heparin, low-dose DX-9065a, or high-dose DX-9065a. RESULTS: The primary efficacy endpoint of death, myocardial infarction, urgent revascularization, or ischemia on continuous ST-segment monitoring occurred in 33.6%, 34.3%, and 31.3% of patients assigned to heparin, low-dose DX-9065a, and high-dose DX-9065a (P = 0.91 for heparin vs. combined DX-9065a). The composite of death, myocardial infarction, or urgent revascularization occurred in 19.5%, 19.3%, and 11.9% (P = 0.125 for heparin vs. high-dose DX-9065a) of patients; major or minor bleeding occurred in 7.7%, 4.2%, and 7.0% of patients; and major bleeding in 3.3%, 0.8%, and 0.9% of patients. Higher concentrations of DX-9065a were associated with a lower likelihood of ischemic events (P = 0.03) and a non-significant tendency toward a higher likelihood of major bleeding (P = 0.32). CONCLUSIONS: In this small phase II trial, there was a non-significant tendency toward a reduction in ischemic events and bleeding with DX-9065a compared with heparin in patients with acute coronary syndromes. The absence of an effect on ST-monitor ischemia warrants further investigation. These data provide the rationale for adequately powered studies of DX-9065a in acute coronary syndromes or percutaneous intervention.

Acute Disease↗
PubMed2005

Variations in the behaviors to novel objects among five inbred strains of mice.

Novelty stimuli cause various behavioral responses, such as exploration and avoidance, and contextual variables may contribute to the behavioral outputs. Here, we tried to compare the behavioral responses to novel objects of five inbred strains of mice (C57BL/6J, 129/svJae, C3H/HeJ, BALB/cJ and DBA/2J) by using a modified novel object test where a small light-weight cube wrapped with paper was presented to mice in a home cage without beddings. In response to these objects, the C57BL/6J, 129/svJae and C3H/HeJ mice showed mild exploratory behaviors, such as approaching, sniffing or brief contact. In striking contrast, the BALB/cJ and DBA/2J mice, which have been known to show high avoidance/low exploration in other behavioral paradigms, exhibited play-like secondary reactions toward the objects after initial primary exploratory behaviors. Specifically, DBA/2J mice would move the object around in the cage, holding it with their mouths, and BALB/cJ mice would gnaw the object, eventually stripping off the wrapping paper. Such behaviors decreased when similar objects were presented repeatedly. The present results suggest that active manipulations of novel objects may be a relevant parameter for measuring novelty-induced behaviors in mice and appear to be strongly influenced by genetic factors.

Animals↗
PubMed2005

Atazanavir signature I50L resistance substitution accounts for unique phenotype of increased susceptibility to other protease inhibitors in a variety of human immunodeficiency virus type 1 genetic backbones.

Substitution of leucine for isoleucine at residue 50 (I50L) of human immunodeficiency virus (HIV) protease is the signature substitution for atazanavir (ATV) resistance. A unique phenotypic profile has been associated with viruses containing the I50L substitution, which produces ATV-specific resistance and increased susceptibility to most other approved HIV protease inhibitors (PIs). The basis for this unique phenotype has not been clearly elucidated. In this report, a direct effect of I50L on the susceptibility to the PI class is described. Cell-based protease assays using wild-type and PI-resistant proteases from laboratory and clinical isolates and in vitro antiviral assays were used to demonstrate a strong concordance between changes in PI susceptibility at the level of protease inhibition and changes in susceptibility observed at the level of virus infection. The results show that the induction of ATV resistance and increased susceptibility to other PIs by the I50L substitution is likely determined at the level of protease inhibition. Moreover, the I50L substitution functions to increase PI susceptibility even in the presence of other primary and secondary PI resistance substitutions. These findings may have implications regarding the optimal sequencing of PI therapies necessary to preserve PI treatment options of patients with ATV-resistant HIV infections.

Amino Acid Substitution↗
PubMed2005

Relation of sexual risks and prevention practices with individuals' stigmatising beliefs towards HIV infected individuals: an exploratory study.

OBJECTIVE: To investigate how an individual's stigmatising beliefs towards people living with HIV are related to his or her own sexual risk and protective behaviours. METHODS: A cross sectional survey was conducted to assess HIV related stigmatising beliefs, risk sexual behaviours, and preventive practices among sexually experienced rural to urban migrants aged 18-30 years in 2002 in Beijing and Nanjing, two large Chinese cities. RESULTS: Among 2153 migrants, 7.2% reported having had more than one sexual partner in the previous month, 9.9% had commercial sex partners, and 12.5% had an episode of a sexually transmitted disease (STD). Only 18% reported frequently or always using condoms, with 20% sometimes or occasionally using them. 57% of the Chinese migrants were willing to take a voluntary HIV test, and 65% had HIV related stigmatising beliefs towards people living with HIV. Multiple logistic regression analysis depicts that individual's stigmatising beliefs towards people with HIV were positively associated with having had an episode of an STD, having multiple sex partners, or having had commercial sex partners, and were negatively associated with condom use and the willingness to accept an HIV test. CONCLUSION: The finding that one's own stigmatising belief is a potential barrier to HIV related preventive practices highlights the difficulties and challenges in implementing behavioural interventions.

Adolescent↗
PubMed2005

Tuberculosis in Calgary, Canada, 1995-2002: site of disease and drug susceptibility.

SETTING: A centre managing all tuberculosis (TB) cases in the population of the Calgary region in Canada. OBJECTIVE: To facilitate the diagnosis and management of TB by examining the distribution of TB by site of disease and the prevalence and pattern of drug-resistant Mycobacterium tuberculosis in a north American setting. DESIGN: A retrospective analysis of data collected at the time of diagnosis of all TB cases recorded during the 8-year period 1995-2002. Data collected included demographic information, site of disease, method of diagnosis and M. tuberculosis drug susceptibility. RESULTS: During the 8-year period, 435 cases of TB were diagnosed: 49% had exclusively extra-pulmonary disease. Lymph node disease (usually cervical) accounted for 44% of the extra-pulmonary cases. A culture of M. tuberculosis resistant to at least one first-line anti-tuberculosis drug was detected in 16% of the initial isolates. All of the resistant strains were found in foreign-born patients and resistance was more common in patients from Asia (19%) and in previously treated patients (26%). CONCLUSION: Extra-pulmonary TB is common in the foreign-born population in the Calgary region, and this pattern may be more widespread than is realised. Drug-resistant strains of TB were more common in foreign-born and previously treated patients.

Alberta↗
PubMed2004

The value of plant collections in ethnopharmacology: a case study of an 85-year-old black cohosh (Actaea racemosa L.) sample.

Ethnopharmacological collections of plants used in traditional medical systems are a valuable but often underappreciated resource for scientific investigation. These collections contain many samples of plants currently employed in herbal and pharmaceutical medicine, and questions on stability and storage life can be examined using these historic collections as vouchers. A sample of black cohosh (Actaea racemosa L.), collected in 1919 by the physician and plant explorer Henry Hurd Rusby, was recently identified in the collections of The New York Botanical Garden and analyzed for its triterpene glycosidic and phenolic constituents qualitatively and quantitatively by high-performance liquid chromatography-photodiode array detector (HPLC-PDA) and liquid chromatography-mass spectrophotometry (LC-MS). A comparison of the triterpene glycosidic and phenolic constituents of the 85-year-old plant sample with those of a modern collection of Actaea racemosa showed the similarity of the two samples, confirming the stability of the older sample, despite its curation over the years under a variety of conditions. Quantitative analyses indicated that both plant samples have similar amounts of the four major triterpene glycosides, but the total amount of the six major phenolic constituents measured in the 85-year-old plant material is lower than the amount measured in the modern plant material. Methanol extracts of the two plant materials were tested for their antioxidant activity, and both extracts showed similar antioxidant activity.

Antioxidants↗
PubMed2004

Functional and molecular characterization of a volume-activated chloride channel in rabbit corneal epithelial cells.

We characterized the functional and molecular properties of a volume-regulated anion channel (VRAC) in SV40-immortalized rabbit corneal epithelial cells (tRCE), since they mediate a robust regulatory volume decrease (RVD) response during exposure to a hypotonic challenge. Whole-cell patch clamp-monitored chloride currents and light-scattering measurements evaluated temporal cell-volume responsiveness to hypoosmotic challenges. Exposure to 200 mOsm medium elicited an outwardly-rectifying current (VACC), which was reversible upon reperfusion with isotonic (300 mOsm) medium. VACC and RVD were chloride-dependent because either chloride removal or application of NPPB (100 microM) suppressed these responses. VACC behavior exhibited voltage-dependent inhibition in the presence of DIDS (500 microM), whereas inhibition by both NPPB (100 microM) and niflumic acid (500 microM) was voltage-independent. VACC was insensitive to glibenclamide (250 microM), verapamil (500 microM) or removal of extracellular calcium. Phorbol dibutyrate, PDBu, (100 nM) had no effect on activated VACC. However, preincubation with PDBu prior to hypotonic challenge prevented VACC and RVD responses as well as prolonged characteristic time. An inactive phorbol ester analogue had no effect on RVD behavior. Moreover, Northern blot analysis verified expression of ClC-3 gene transcripts. The presence of ClC-3 transcripts along with the correspondence between the effects of known ClC-3 inhibitors on VACC and RVD suggest that ClC-3 activation underlies these responses to hypotonic-induced cell swelling.

Animals↗
PubMed2004

Genome-wide analysis of defense-responsive genes in bacterial blight resistance of rice mediated by the recessive R gene xa13.

Defense responses triggered by dominant and recessive disease resistance (R) genes are presumed to be regulated by different molecular mechanisms. In order to characterize the genes activated in defense responses against bacterial blight mediated by the recessive R gene xa13, two pathogen-induced subtraction cDNA libraries were constructed using the resistant rice line IRBB13--which carries xa13--and its susceptible, near-isogenic, parental line IR24. Clustering analysis of expressed sequence tags (ESTs) identified 702 unique expressed sequences as being involved in the defense responses triggered by xa13; 16% of these are new rice ESTs. These sequences define 702 genes, putatively encoding a wide range of products, including defense-responsive genes commonly involved in different host-pathogen interactions, genes that have not previously been reported to be associated with pathogen-induced defense responses, and genes (38%) with no homology to previously described functional genes. In addition, R-like genes putatively encoding nucleotide-binding site/leucine rich repeat (NBS-LRR) and LRR receptor kinase proteins were observed to be induced in the disease resistance activated by xa13. A total of 568 defense-responsive ESTs were mapped to 588 loci on the rice molecular linkage map through bioinformatic analysis. About 48% of the mapped ESTs co-localized with quantitative trait loci (QTLs) for resistance to various rice diseases, including bacterial blight, rice blast, sheath blight and yellow mottle virus. Furthermore, some defense-responsive sequences were conserved at similar locations on different chromosomes. These results reveal the complexity of xa13-mediated resistance. The information obtained in this study provides a large source of candidate genes for understanding the molecular bases of defense responses activated by recessive R genes and of quantitative disease resistance.

Chromosomes, Plant↗