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Biomedical subjects

Yue Chen

Publications and source records attributed to Yue Chen.

At least 91 records · Page 5Linked to original sources
PubMed2005

Differential effect of damp housing on respiratory health in women.

OBJECTIVE: To investigate the effect of exposure to damp housing on respiratory symptoms in women and men. METHOD: We examined sex differences in the relationship between damp housing and respiratory symptoms in a cross-sectional survey of 1988 adults, 18 to 74 years of age, using a self-administered questionnaire. We used chi (2) and t-tests to test associations between potential risk factors and respiratory symptoms in men and women. We used multiple logistic regression modelling to determine adjusted odds ratios for several possible symptoms and home dampness. All multivariate analyses were stratified by sex. RESULTS: Men had a significantly higher prevalence of chronic wheeze compared with women. The prevalence of chronic wheeze, wheeze with shortness of breath, and allergy were higher for women reporting damp housing compared with those not reporting damp housing. No significant associations between damp housing and respiratory symptoms were found in men. CONCLUSION: These data raise the possibility that women may be more susceptible to the effects of damp housing than men are.

Adult↗
PubMed2004

Use of a Clostridium perfringens vector to express high levels of SIV p27 protein for the development of an oral SIV vaccine.

Clostridium perfringens is a normal bacterial flora of the small and large intestines of humans and other animals. The current study investigates the potential use of a noncytotoxic C. perfringens as an oral vaccine vehicle for expression and intestinal delivery of a large amount of SIV antigens. Here we report the construction of a recombinant C. perfringens vaccine vector expressing high levels of SIV p27 during sporulation. Following oral administration of this recombinant C. perfringens vaccine vector to mice, large amounts of intact p27 protein were detected in the terminal ileum where the majority of Peyer's Patches (PPs) are located. Furthermore, dendritic cells (DCs) beneath the mucosal surface in the PPs were able to capture SIV p27 antigen, when PPs were exposed to C. perfringens expressing SIV p27 antigen. In addition, uptake of C. perfringens was able to induce maturation of mouse DCs. These results support the potential use of C. perfringens as an oral SIV/HIV vaccine vector.

Administration, Oral↗
PubMed2004

Effect of short-term exposure to low levels of gaseous pollutants on chronic obstructive pulmonary disease hospitalizations.

We examined the associations between gaseous pollutants and hospitalization for chronic obstructive pulmonary diseases (COPD) among elderly people living in Vancouver, British Columbia, Canada, a city in which ambient air pollution levels are relatively low. We regressed the logarithm of daily counts of acute COPD hospitalization during the 5-year period from 1994 to 1998 on the daily mean levels of each pollutant, after accounting for seasonal and subseasonal fluctuations, non-Poisson dispersion, and weather variables. Nitrogen dioxide and carbon monoxide were significantly associated with hospitalization for COPD, and the magnitude of effects was increased slightly with increasing days of exposure averaging, with the relative risk for a 7-day average being 1.11 (95%CI: 1.04, 1.20) and 1.08 (1.02, 1.13) for nitrogen dioxide and carbon monoxide, respectively. There was no significant association between either sulfur dioxide or ozone and COPD hospitalization. The combined relative risk for all four gaseous pollutants on COPD hospitalization was 1.21. The effects of gaseous pollutants on COPD hospitalization were not significant after adjustment for PM(10), although its inclusion did not have a marked effect on the point estimates for relative risks. Nitrogen dioxide has a significant impact on COPD hospitalization. Further studies are needed to separate the effects of single pollutants from the combined effects of the complex mixture of air pollutants in urban atmospheres.

Aged↗
PubMed2004

Isolation and characterization of a novel DNA methyltransferase complex linking DNMT3B with components of the mitotic chromosome condensation machinery.

Proper patterns of genome-wide DNA methylation, mediated by DNA methyltransferases DNMT1, -3A and -3B, are essential for embryonic development and genomic stability in mammalian cells. The de novo DNA methyltransferase DNMT3B is of particular interest because it is frequently overexpressed in tumor cells and is mutated in immunodeficiency, centromere instability and facial anomalies (ICF) syndrome. In order to gain a better understanding of DNMT3B, in terms of the targeting of its methylation activity and its role in genome stability, we biochemically purified endogenous DNMT3B from HeLa cells. DNMT3B co-purifies and interacts, both in vivo and in vitro, with several components of the condensin complex (hCAP-C, hCAP-E and hCAP-G) and KIF4A. Condensin mediates genome-wide chromosome condensation at the onset of mitosis and is critical for proper segregation of sister chromatids. KIF4A is proposed to be a motor protein carrying DNA as cargo. DNMT3B also interacts with histone deacetylase 1 (HDAC1), the co-repressor SIN3A and the ATP-dependent chromatin remodeling enzyme hSNF2H. Further more, DNMT3B co-localizes with condensin and KIF4A on condensed chromosomes throughout mitosis. These studies therefore reveal the first direct link between the machineries regulating DNA methylation and mitotic chromosome condensation in mammalian cells.

Adenosine Triphosphatases↗
PubMed2004

A novel protein tyrosine kinase NOK that shares homology with platelet- derived growth factor/fibroblast growth factor receptors induces tumorigenesis and metastasis in nude mice.

Receptor protein tyrosine kinases (RPTKs) play important roles in the regulation of a variety of cellular processes including cell migration, proliferation, and protection from apoptosis. Here, we report the identification and characterization of a novel RPTK-like molecule that has a critical role in induction of tumorigenesis and metastasis and is termed Novel Oncogene with Kinase-domain (NOK). NOK contains a putative single transmembrane domain and a conserved intracellular tyrosine kinase domain that shares homology with members of the platelet-derived growth factor/fibroblast growth factor receptor superfamily. NOK was exclusively located in the cytoplasm. NOK mRNAs were detected in limited human organs and expressed with the highest abundance in the prostate. A variety of tumor cells also expressed the NOK mRNAs. We demonstrated that NIH3T3 and BaF3 cells could be strongly transformed by the expression of the NOK gene as examined by colony formation experiment. In addition, BaF3 cells with the stable expression of NOK induced rapid tumorigenesis in nude mice. Interestingly, these NOK-expressing tumor cells could promptly invade and spread into various distinct organs and form metastatic foci, eventually leading to the rapid death of these animals. Moreover, molecular mechanism studies indicated that NOK could concomitantly activate both MAP kinase and phosphatidylinositol 3'-kinases (PI3K) pathways in stable BaF3 cells. Thus, our results both in vitro and in vivo suggest that NOK is a novel oncogene with the capacity of promoting cell transformation, tumorigenesis, and metastasis.

Animals↗
PubMed2004

Compromised late-stage motion processing in schizophrenia.

BACKGROUND: Visual motion processing is compromised in schizophrenia, as shown in deficient velocity discrimination. Processing of motion signals comprises progressive stages along the geniculate-striate-extrastriate-cortex pathway. Based on neurophysiologic and brain lesion studies, a velocity discrimination deficit can implicate early-stage motion processing if it is contrast-dependent or late-stage motion processing if it is contrast-independent. METHODS: To determine which stage underlies the deficient velocity discrimination in schizophrenia, we examined the effects of visual contrast on velocity discrimination. We measured velocity discrimination thresholds in schizophrenia patients (n = 34) and normal control subjects (n = 17) at both low and high contrasts, using each subject's contrast detection threshold to equate contrast levels. RESULTS: Schizophrenia patients showed poor velocity discrimination that improved little with high contrast, whereas normal control subjects showed enhanced velocity discrimination with increased contrast. CONCLUSIONS: The finding that the velocity discrimination deficit in schizophrenia is independent of contrast modulation implicates the later, rather than the earlier, stages of motion processing, which is mediated in the extrastriate cortex.

Adult↗
PubMed2004

Gaseous air pollutants and asthma hospitalization of children with low household income in Vancouver, British Columbia, Canada.

Associations of gaseous air pollutants (including carbon monoxide, sulfur dioxide, nitrogen dioxide, and ozone) with asthma hospitalization, stratified by sex and socioeconomic status, were examined among children 6-12 years of age in Vancouver, British Columbia, Canada, between 1987 and 1998. Relative risks for an exposure increment corresponding to the interquartile range for each gaseous air pollutant were estimated for asthma hospitalization after adjustment for weather conditions, including daily maximum and minimum temperatures as well as average relative humidity. Similar results were obtained by using locally weighted smoothing functions (LOESS) with default convergence criteria and by using natural cubic splines with a more stringent setting. Exposures to nitrogen dioxide were found to be significantly and positively associated with asthma hospitalization for males in the low socioeconomic group but not in the high socioeconomic group. For females, this same pattern of association was observed for exposures to sulfur dioxide. No significantly positive associations were found between carbon monoxide and ozone and asthma hospitalization in either low or high socioeconomic groups.

Air Pollutants↗
PubMed2004

Ecological measures of socioeconomic status and hospital readmissions for asthma among Canadian adults.

BACKGROUND: Lack of an association between area-based socioeconomic status (SES) and readmission for asthma was investigated in a country with a universal health care system. METHODS: Data linkage analysis was conducted based on hospitalization data from Statistics Canada's Person-oriented Information Database and area-based SES data from the 1996 Census. Hospital records for 8333 asthma patients aged 20-64 years in all Canadian provinces except Quebec who were admitted in 1995/1996 were linked to determine the number of patients who were rehospitalized within the same fiscal year. The area-based SES of the patients was defined according to the average personal income and proportion of residents with a university degree in an enumeration area (EA). Incidence rates of readmission for asthma were calculated based on the total years at risk. Cox's proportional hazard model was used to adjust for age, sex, province, and length of stay for first admission. RESULTS: The incidence rate of asthma rehospitalization was 31.6 per 100 person-years for men and 37.2 per 100 person-years for women. Neither average EA income or education level was significantly associated with rehospitalization for asthma. Women living in poor areas tended to have an increased incidence of asthma rehospitalization, but the difference was not significant after adjustment for covariates using the Cox regression model. CONCLUSION: Socioeconomic status measured at the neighborhood level has no significant impact on rehospitalization for asthma among Canadian adults.

Adult↗
PubMed2004

Determinants of breast-feeding and weaning in Alberta, Canada.

OBJECTIVE: To assess the determinants of breast-feeding initiation and duration at the population level in Alberta, Canada. METHODS: Determinants of breast-feeding were assessed based on data from a sample of 1113 women, who represented 150,898 fertile women in Alberta, in the second cycle of the National Population Health Survey conducted 1996-97. Logistic regression analysis was used to estimate the independent effects of various determinants of breast-feeding initiation and duration dichotomized at 4 weeks, 8 weeks, 12 weeks, and 6 months postpartum. All analyses used analytic weights to take both the average design effect and population weights for the complex survey design into account. RESULTS: The proportion of breast-feeding initiation was 85.6%. It was observed that 71.3% of mothers continued breast-feeding for at least 3 months, and 37.2% of mothers breast-fed their infants for more than 6 months. Determinants of breast-feeding initiation were marital status, education, maternal smoking behaviour, and annual family income. White women and women who were older than 35 years of age were more likely to continue breast-feeding for longer periods, whereas those who smoked during pregnancy were less likely to breast-feed their infants for extended periods. The primary reasons for weaning were breast problems at less than 1 week, insufficient milk production during weeks 1 to 12, and infants who weaned themselves after 3 months. CONCLUSIONS: Smoking cessation during pregnancy, adequate treatment of early breast problems, and breast-feeding promotion campaigns targeting socioeconomically disadvantaged populations could serve to increase breast-feeding in Canada.

Adolescent↗
PubMed2004

HBV infection and familial aggregation of liver cancer: an analysis of case-control family study.

OBJECTIVES: Hepatitis B virus (HBV) infection is one of the most important risk factors for hepatocellular carcinoma (HCC). The specific aim of this study is to assess the influence of HBV infection on familial aggregation of HCC. METHODS: We conducted a population-based case-control family study of liver cancer in Taixing, China, in 2001-2002, with a total of 3611 individuals from 202 case families and 202 control families. Conditional logistic regression was used for the case-control data. The approach of GEE2 was used to analyze the family data and age and sex were adjusted in all marginal regression models. RESULTS: The odds ratio for HBV associated with HCC was 41.39 (95% confidence interval (CI): 23.03-74.30). The relatives of cases had a higher risk of liver cancer compared with the relatives of controls with a conditional odds-ratio of 3.06 (95% CI: 1.48-6.33). The association parameters among first- and second-degree relatives were no longer statistically significant when HbsAg was taken into consideration. CONCLUSION: HBV infection was likely a main reason for the familial aggregation of liver cancer in Southern China.

Adult↗
PubMed2004

Influence of relatively low level of particulate ar pollution on hospitalization for COPD in elderly people.

To assess the association between relatively low levels of size-fractioned particulate matter (PM) and hospitalization for chronic obstructive pulmonary disease (COPD), we conducted a time-series analysis among elderly people 65 yr of age or more living in Vancouver between June 1995 and March 1999. Measures of thoracic PM (PM(10)), fine PM (PM(2.5)), coarse PM (PM(10-2.5)), and coefficient of haze (COH) were examined over periods varying from 1 to 7 days prior to hospital admissions. Generalized additive models (GAMs; general linear models, GLMs) were used, and temporal trends and seasonal and subseasonal cycles in COPD hospitalizations were removed by using GLM with parametric natural cubic splines. The relative risks were calculated based on an incremental exposure corresponding to the interquartile range of these measures, and were adjusted for daily weather conditions and gaseous pollutants. PM measures had a positive effect on COPD hospitalization, especially 0 to 2 days prior to the admissions, before copollutants were accounted for. For 3-day average levels of exposure the relative risk estimates were 1.13 (95% confidence interval: 1.05-1.21) for PM(10), 1.08 (1.02-1.15) for PM(2.5), 1.09 (1.03-1.16) for PM(10-2.5), and 1.05 (1.01-1.09) for COH. The associations were no longer significant when NO(2) was included in the models. We concluded that the particle-related measures were significantly associated with COPD hospitalization in the Vancouver area, where the level of air pollution is relatively low, but the effects were not independent of other air pollutants.

Aged↗
PubMed2004

CHIP mediates degradation of Smad proteins and potentially regulates Smad-induced transcription.

Transforming growth factor beta (TGF-beta)/bone morphogenetic protein (BMP) family ligands interact with specific membrane receptor complexes that have serine/threonine kinase activities. The receptor phosphorylation and activation induced by the ligands leads to phosphorylation of the Smad proteins, which translocate to the nucleus, controlling gene expression. Thus, regulation of Smad proteins is a key step in TGF-beta/BMP-induced signal transduction. Here we report a novel mechanism of the regulation of SMAD-mediated signaling, by which the Smad1 protein level is controlled through expression of the CHIP protein. CHIP is a U-box-dependent E3 ubiquitin ligase, previously identified as a cochaperon protein. However, we have isolated CHIP as a Smad-interacting protein in a yeast two-hybrid screen using Smad1 as bait. Furthermore we have shown CHIP-Smad interaction using the (35)S-labeled CHIP protein, which can interact with glutathione S-transferase (GST)-Smad1 and GST-Smad4 in an in vitro protein-binding assay. The CHIP-Smad interaction has been confirmed in vivo in mammalian cells through coimmunoprecipitation. Interestingly, we demonstrate that the coexpression of Smad1 and Smad4 with the CHIP protein results in the degradation of the Smad proteins through a ubiquitin-mediated process. Consistent with the observation that CHIP induces Smad1 degradation, we further show that the expression of CHIP can inhibit the transcriptional activities of the Smad1/Smad4 complex induced by BMP signals. Intriguingly, pBS/U6/CHIPi, which diminishes CHIP expression, significantly enhanced Smad1/Smad4- or BMPRIB(QD)-induced gene transcription. These results suggest that CHIP can interact with the Smad1/Smad4 proteins and block BMP signal transduction through the ubiquitin-mediated degradation of Smad proteins.

Binding Sites↗
PubMed2004

Two visual motion processing deficits in developmental dyslexia associated with different reading skills deficits.

Developmental dyslexia is associated with deficits in the processing of visual motion stimuli, and some evidence suggests that these motion processing deficits are related to various reading subskills deficits. However, little is known about the mechanisms underlying such associations. This study lays a richer groundwork for exploration of such mechanisms by more comprehensively and rigorously characterizing the relationship between motion processing deficits and reading subskills deficits. Thirty-six adult participants, 19 of whom had a history of developmental dyslexia, completed a battery of visual, cognitive, and reading tests. This battery combined motion processing and reading subskills measures used across previous studies and added carefully matched visual processing control tasks. Results suggest that there are in fact two distinct motion processing deficits in developmental dyslexia, rather than one as assumed by previous research, and that each of these deficits is associated with a different type of reading subskills deficit. A deficit in detecting coherent motion is selectively associated with low accuracy on reading subskills tests, and a deficit in discriminating velocities is selectively associated with slow performance on these same tests. In addition, evidence from visual processing control tasks as well as self-reports of ADHD symptoms suggests that these motion processing deficits are specific to the domain of visual motion, and result neither from a broader visual deficit, nor from the sort of generalized attention deficit commonly comorbid with developmental dyslexia. Finally, dissociation between these two motion processing deficits suggests that they may have distinct neural and functional underpinnings. The two distinct patterns of motion processing and reading deficits demonstrated by this study may reflect separable underlying neurocognitive mechanisms of developmental dyslexia.

Adult↗
PubMed2004

Effect of weight reduction on respiratory function and airway reactivity in obese women.

BACKGROUND: Population-based studies have documented an association between obesity and an increased prevalence of asthma in women. METHODS: We prospectively studied 58 obese women with a body mass index of > 30 kg/m(2), 24 of whom had asthma, who were enrolled in an intensive 6-month weight loss program to determine whether loss of body mass would be correlated with improvements in bronchial reactivity, lung function, and disease-specific health status. RESULTS: Patients lost an average of 20 kg over the 6-month period. For every 10% relative loss of weight, the FVC improved by 92 mL (p = 0.05) and the FEV(1) improved by 73 mL (p = 0.04), however, bronchial reactivity did not significantly change with weight loss (p = 0.23). Patients who lost > 13% of their pretreatment weight experienced improvements in FEV(1) (p = 0.01), FVC (p = 0.02), and total lung capacity (p = 0.05) compared to patients in the lowest quartile who failed to lose significant amounts of weight. Neither group experienced any significant change in methacholine responsiveness (p = 0.57). Patients who completed the 6-month weight loss program experienced improvements in respiratory health status, irrespective of weight loss. CONCLUSION: We concluded that weight loss can improve lung function in obese women, however, the improvements appear to be independent of changes in airway reactivity.

Adult↗
PubMed2004

Effects of overexpression of CXCL10 (cytokine-responsive gene-2) on MA-10 mouse Leydig tumor cell steroidogenesis and proliferation.

Chemokines have been implicated in tumor growth, angiogenesis, metastasis and the host immune response to malignant cells. Infection and autoimmune disorders can reduce androgen production by Leydig cells and adversely affect spermatogenesis. Cytokine-responsive gene-2 (crg-2) (systematic name CXCL10, also known as interferon-gamma-inducible protein 10 (IP-10)) is a potent chemokine expressed predominantly by macrophages and Leydig cells in the testis. CXCL10 binds to CXCR3 receptor (a G-protein-coupled receptor) and acts via Gialpha protein. We have shown previously that CXCL10 is differentially expressed in normal Leydig cells, inhibited by human chorionic gonadotropin and induced by interferon-gamma, interleukin-1alpha and tumor necrosis factor-alpha. The purpose of the present study was to determine the effects of overexpression of CXCL10 by transfection experiments in MA-10 cells on cell growth, CXCR3 expression, progesterone synthesis and steroidogenic acute regulatory protein (StAR D1, a key regulatory factor in steroidogenesis) gene expression. We cloned the complete CXCL10 cDNA in a mammalian expression vector with the CMV promoter, pcDNA3.1D/V5-His-TOPO, and confirmed its expression with rat CXCL10 antibody and V5 antibody. Results showed large amounts of CXCL10 protein secreted in the medium in the CXCL10 transfectants by Western blotting. The production of CXCL10 mRNA ranged from 30-50-fold more (n=6) in the transfected cells than the control cells, as determined by semiquantitative and real-time RT-PCR. 8-Br-cAMP downregulated CXCL10 mRNA expression and stimulated CXCR3 mRNA expression. Transfection of MA-10 cells with CXCL10 decreased cAMP-induced progesterone synthesis from 38.5+/-1.7 ng/ml (1.5 x 10(5) cells/ml) in control cells to 23.2+/-1.5 ng in transfected cells (P<0.01). 8-Br-cAMP (0.2 mM)-induced StAR D1 mRNA was decreased 30-40% by transfection with CXCL10. Interestingly, overexpression of CXCL10 induced the expression of its receptor CXCR3 gene, as determined by RT-PCR and fluorescence-activated cell sorter (FACS) analysis. Transfection of CXCL10 also significantly decreased insulin-like growth factor-I (IGF-I, 100 ng/ ml)-induced [3H]thymidine incorporation into DNA. These data suggest that CXCL10 also inhibits MA-10 tumor cell proliferation. In conclusion, CXCL10 inhibits StAR D1 expression, decreases progesterone synthesis and inhibits cell proliferation. CXCL10 has the potential to be used in gene therapy for prostate cancer due to its antiangiogenic effect and its inhibitory effect on steroidogenesis.

Animals↗
PubMed2004

Association between particulate air pollution and first hospital admission for childhood respiratory illness in Vancouver, Canada.

In this study, the authors assessed the impact of particulate air pollution on first respiratory hospitalization. Study subjects were children less than 3 years of age living in Vancouver, British Columbia, who had their first hospitalization as a result of any respiratory disease (ICD-9 codes 460-519) during the period from June 1, 1995, to March 31, 1999. The authors used logistic regression to estimate the associations between ambient concentrations of particulate matter (PM) and first hospitalization. The adjusted odds ratios for first respiratory hospitalization associated with mean and maximal PM10-2.5 with a lag of 3 days were 1.12 (95% confidence interval: 0.98, 1.28) and 1.13 (1.00, 1.27). After adjustment for gaseous pollutants, the corresponding odds ratios were 1.22 (1.02, 1.48) and 1.14 (0.99, 1.32). The data indicated the possibility of harmful effects from coarse PM on first hospitalization for respiratory disease in early childhood.

Air Pollutants↗
PubMed2004

[Expression of telomerase reverse transcriptase and its significance in human fetal lung development].

OBJECTIVE: To investigate the expression and distribution of telomerase reverse transcriptase (hTERT) and its significance during the development of epithelial stem cells in human fatal lungs. METHODS: Human lung tissues were obtained at abortion from 37 fetuses 10-34 weeks of gestational age with parental consent, and the expression of hTERT in these tissues was examined by immunohistochemistry. RESULTS: In fetuses of 10 weeks old, hTERT was detected mainly in the epithelial cells of the proximal bronchi in the fetal lung, and migrated gradually to the distal bronchi as the lung developed. The hTERT expression level peaked at 17-20 weeks of gestation and then decreased over the period of alveolarization that occurred at about 25-26 weeks. In the later gestation period, strongly positive epithelial cells became concentrated in discrete patches near the basal membrane of the airway and scattered in only a few of the pulmonary alveoli. Morphologically, these cells resembled the basal cells and type II alveolar epithelial cells (AEC) or their progenitor cells. CONCLUSIONS: Telomerase expression and activity are hallmarks of the pulmonary stem or progenitor cells that maintain undifferentiated state and self-renewal capacity, and it plays a crucial role in the normal differentiation and regeneration of the bronchial and alveolar epithelial cells to maintain the epithelial integrity.

DNA-Binding Proteins↗