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Biomedical subjects

Yue Chen

Publications and source records attributed to Yue Chen.

At least 55 records · Page 3Linked to original sources
PubMed2005

An epidemiological study of primary nocturnal enuresis in Chinese children and adolescents.

AIMS: Assessment of the prevalence of primary nocturnal enuresis (PNE) and its risk factors in Chinese children and adolescents in the central areas of mainland China. METHODS: A cross-sectional study of PNE was performed by distributing 11799 self-administered questionnaires to parents of 5-18-year-old students in 32 schools of Henan province China. The questionnaire asked about sociodemographic data, PNE data, physical or psychological disorders, and family stressors. The PNE children were divided into a pediatric group (age 5-12) and an adolescent group (age 13-18). RESULTS: The response rate was 88% (10383/11799) in which 10088 (85.5%) were qualified to enter the final statistical analysis. The overall prevalence of PNE was 4.07% (95%CI 3.68-4.46) and that of marked PNE was 1.46% (95%CI 1.23-1.69). PNE was significantly more in boys than in girls. The prevalence decreased with age without gender bias. Of all enuretic children, 21.17% had daytime urinary symptoms and 22.87% had a positive family history. Only 6.08% of PNE had sought professional help. The episodic severity of PNE, associated daytime symptoms, positive family history, and seeking for professional help in adolescent group were significantly higher than those of pediatric group. Age, inhabitation (living in rural or urban areas), arousal dysfunction, associated daytime symptoms and family history were found to be significant predictors of marked PNE. Among PNE cases with a positive family history, there was no significant difference in the familial distribution between boys and girls. CONCLUSIONS: The prevalence of age-related PNE from Chinese school children is lower than those reported from western countries and other Asian countries. Age, inhabitation (rural or urban), arousal dysfunction, associated daytime symptom and family history are significant as predictors of marked PNE. The misconceptions among Chinese parents require health education intervention.

Adolescent↗
PubMed2005

High-throughput identification of in-gel digested proteins by rapid, isocratic HPLC/MS/MS.

The high sensitivity and accuracy of mass spectrometry for identifying proteins has led to an explosive expansion of proteomics research, necessitating rapid procedures for HPLC/MS/MS analysis. Current HPLC/MS/MS analysis usually relies on elution of peptides from the HPLC column with a gradient that takes a total of 45-70 min for each cycle, limiting sample throughput and the speed of protein identification. Here we report a simple method for high-throughput protein identification, using isocratic, either methanol- or acetonitrile-based buffer systems, HPLC elution into an LTQ mass spectrometer. This procedure allows each cycle of highly sensitive HPLC/MS/MS analysis to be completed in 5 min, thus boosting the efficiency of HPLC/MS/MS analysis 9-14-fold. Using this method, each operator can acquire HPLC/MS/MS data for 96 in-gel proteolytic digests in one 8-h working day. The method can easily be implemented in any laboratory with an LTQ mass spectrometer. This protocol should find wide application in mass spectrometry laboratories that require high-throughput analysis but are limited by inefficient use of machine time.

Acetonitriles↗
PubMed2005

Point mutation at single tyrosine residue of novel oncogene NOK abrogates tumorigenesis in nude mice.

Receptor protein-tyrosine kinases (RPTKs) are tightly regulated during normal cellular processes including cell growth, differentiation, and metabolism. Recently, a RPTK-like molecule named novel oncogene with kinase-domain (NOK) has been cloned and characterized. Overexpression of NOK caused severe cellular transformation as well as tumorigenesis and metastasis in nude mice. In the current study, we generated two tyrosine-->phenylalanine (Y-->F) point mutations (Y327F and Y356F) within the endodomain of NOK that are well conserved in many RPTK subfamilies and are the potential tyrosine phosphorylation sites important for major intracellular signaling. Using BaF3 cells stably expressing the ectodomain of mouse erythropoietin receptor, and the transmembrane and endodomain of NOK (BaF3-E/N), we were able to show that point mutations at either Y327 or Y356 dramatically blocked cellular transformation by NOK as examined by colony formation and cellular DNA synthesis. In addition, tumorigenesis induced by BaF3-E/N was completely abrogated upon the introduction of either single mutation. Importantly, signaling studies revealed that the activation of extracellular signal-regulated kinase was inhibited by Y356F and was significantly reduced by Y327F. Both mutations significantly impaired Akt phosphorylation. Interestingly, both mutations did not affect the kinase activity of NOK. Moreover, apoptotic analysis revealed that both mutations accelerated cell death by activating caspase-3-mediated pathways. Thus, our study shows that these potential tyrosine phosphorylation sites may play critical roles in NOK-mediated tumorigenesis both in vitro and in vivo.

Animals↗
PubMed2005

Maternal cigarette smoking and the risk of pregnancy-induced hypertension and eclampsia.

BACKGROUND: Although previous studies have found that maternal smoking decreases the risk of pregnancy-induced hypertension (PIH), the difference of this effect between primiparous and multiparous women has not been well studied and the results of the exposure-response relationships between maternal smoking and PIH are inconsistent. No previous study has specifically examined the relationship between maternal smoking and eclampsia. METHODS: We analysed data from a population-based retrospective cohort study of 3 153 944 singleton pregnancies in the US. The data were derived from the national linked birth/infant mortality database for 1998. Multiple logistic regressions were used to describe the relationship between cigarette smoking and PIH and eclampsia. RESULTS: The adjusted odds ratios (ORs) [95% confidence intervals (95% CIs)] for PIH were 0.80 (0.77-0.83) for primiparous women and 0.81 (0.78-0.83) for multiparous women among smokers compared with non-smokers. The corresponding adjusted ORs (95% CIs) for eclampsia were 0.74 (0.66-0.82) and 0.75 (0.68-0.83), respectively. For PIH, the adjusted OR (95% CI) for smokers vs non-smokers were 0.82 (0.79-0.86), 0.81 (0.78-0.83), 0.80 (0.77-0.83), and 0.88 (0.79-0.98), respectively, for 1-5, 6-10, 11-20, and >20 cigarettes per day (test for trend: P = 0.86). The corresponding figures for eclampsia were 0.85 (0.75-0.95), 0.74 (0.66-0.82), 0.68 (0.58-0.78), and 0.73 (0.49-1.04), respectively (test for trend: P = 0.02). CONCLUSION: Maternal cigarette smoking decreases the risk of PIH and eclampsia, with a significant inverse exposure-response relationship apparent for eclampsia.

Adolescent↗
PubMed2005

Myosin light chain kinase and myosin phosphorylation effect frequency-dependent potentiation of skeletal muscle contraction.

Repetitive stimulation potentiates contractile tension of fast-twitch skeletal muscle. We examined the role of myosin regulatory light chain (RLC) phosphorylation in this physiological response by ablating Ca(2+)/calmodulin-dependent skeletal muscle myosin light chain kinase (MLCK) gene expression. Western blot and quantitative-PCR showed that MLCK is expressed predominantly in fast-twitch skeletal muscle fibers with insignificant amounts in heart and smooth muscle. In contrast, smooth muscle MLCK had a more ubiquitous tissue distribution, with the greatest expression observed in smooth muscle tissue. Ablation of the MYLK2 gene in mice resulted in loss of skeletal muscle MLCK expression, with no change in smooth muscle MLCK expression. In isolated fast-twitch skeletal muscles from these knockout mice, there was no significant increase in RLC phosphorylation in response to repetitive electrical stimulation. Furthermore, isometric twitch-tension potentiation after a brief tetanus (posttetanic twitch potentiation) or low-frequency twitch potentiation (staircase) was attenuated relative to responses in muscles from wild-type mice. Interestingly, the site of phosphorylation of the small amount of monophosphorylated RLC in the knockout mice was the same site phosphorylated by MLCK, indicating a potential alternative signaling pathway affecting contractile potentiation. Loss of skeletal muscle MLCK expression had no effect on cardiac RLC phosphorylation. These results identify myosin light chain phosphorylation by the dedicated skeletal muscle Ca(2+)/calmodulin-dependent MLCK as a primary biochemical mechanism for tension potentiation due to repetitive stimulation in fast-twitch skeletal muscle.

Animals↗
PubMed2005

Synthesis and evaluation of a technetium-99m-labeled diethylenetriaminepentaacetate-deoxyglucose complex ([99mTc]-DTPA-DG) as a potential imaging modality for tumors.

This study describes the radiolabeling and preliminary biologic testing of diethylenetriaminepentaacetic acid (DTPA)-deoxyglucose (DG) labeled with (99m)Tc. A one-step [(99m)Tc]-DTPA-DG kit was prepared using the stannous chloride reduction method. When (99m)TcO(4)(-) was added to the DTPA-DG kit at room temperature the radiochemical purity 30 min later was 99.2%, and it remained >98.6% for 6 h. Rapid blood clearance of [(99m)Tc]-DTPA-DG was observed in in vivo biodistribution, the main route of clearance was via the kidneys. No significant accumulation in any other organs was seen. The tumor-to-brain and tumor-to-muscle concentration ratios for [(99m)Tc]-DTPA-DG uptake were higher than those for fluorine-18-flurodeoxyglucose ((18)F-FDG). Scintigraphic results demonstrated the feasibility of [(99m)Tc]-DTPA-DG imaging tumors. The [(99m)Tc]-DTPA-DG complex is a potential imaging agent due to the ideal physical characteristics of the radionuclide, ease of preparation, low cost, early accumulation and the preference for the renal route of excretion.

Animals↗
PubMed2005

Construction and characterization of an infectious molecular clone of HIV-1 subtype A of Indian origin.

India has the second highest number of HIV-1 infected people next to South Africa. The predominant proportion of HIV-1 circulating in India is of subtype C origin, with a small fraction made up of subtypes A and B. In this report, we describe the construction and characterization of the first full-length infectious molecular clone p1579A-1 HIV-1, from an HIV-1 subtype A infected person from India, using long PCR and successive ligation of the amplimers. Phylogenetic analysis of the sequence of the entire proviral DNA and LTR confirmed p1579A-1 to be an HIV-1 subtype A. Analysis of the env gene of p1579A-1 showed a conserved GPGQ motif and the absence of basic amino acids at positions 11 and 25 suggesting CCR5 coreceptor usage. Analysis of env N-linked glycosylation sites revealed fewer sites in the V1 region of envelope compared to other subtype A. Transcription factor binding site analysis of the LTR sequences identified conserved as well as unique transcription factor binding sites (TFBS) in p1579A-1. This infectious clone of HIV-1 can be useful to study the molecular mechanism of dominance of subtype C in India.

Adolescent↗
PubMed2005

In a retrospective study of chronic obstructive pulmonary disease inpatients, respiratory comorbidities were significantly associated with prognosis.

BACKGROUND AND OBJECTIVE: Comorbidities may be related to the prognosis for chronic obstructive pulmonary disease (COPD). We examined respiratory comorbidities associated with length of stay and in-hospital mortality among COPD patients. METHODS: We used the Hospital Person Oriented Information (HPOI) database of Statistics Canada for a 5-year period. Over 4 years (fiscal years 1994-1995 to 1998-1999), 143,135 records listed COPD as the most responsible diagnosis for men and 122,065 records for women aged 40 years or more, and 75,780 men and 69,539 women were admitted to hospital at least once. Logistic regression modeling was used to examine the relationships between respiratory comorbidities and hospital outcomes adjusting for covariates. RESULTS: Of the COPD patients, 10% had pneumonia-influenza and 3% had asthma as comorbid conditions. Women had a higher prevalence of asthma than men. The median length of stay at hospital was approximately 7 days, and 95% of patients were discharged alive. The odds ratio (95% confidence interval) for pneumonia-influenza in relation to in-hospital death was 3.56 (3.31, 3.83) for men and 3.29 (3.00, 3.61) for women. For comorbid asthma the corresponding odds ratios were 0.56 (0.36, 0.61) and 0.54 (0.35, 0.57), respectively. CONCLUSIONS: COPD inpatients with pneumonia-influenza had a worse prognosis and those with asthma had a better prognosis.

Adult↗
PubMed2005

Cancer mortality among US men and women with asthma and hay fever.

The relation between self-reported physician-diagnosed asthma and/or hay fever and cancer mortality was explored in a prospective cohort study of 1,102,247 US men and women who were cancer-free at baseline. During 18 years of follow-up, from 1982 to 2000, there were 81,114 cancer deaths. Cox proportional hazards models were used to obtain adjusted relative risks for all cancer mortality and for cancer mortality at 12 sites associated with allergy indicators. There were significant inverse associations between a history of both asthma and hay fever and overall cancer mortality (relative risk (RR) = 0.88, 95% confidence interval (CI): 0.83, 0.93) and colorectal cancer mortality (RR = 0.76, 95% CI: 0.64, 0.91) in comparison with persons with neither of these allergic conditions. A history of hay fever only was associated with a significantly lowered risk of pancreatic cancer mortality, and a history of asthma only was associated with a significantly lowered risk of leukemia mortality. In never smokers, these associations persisted but were no longer significant. Results for mortality from cancer at other sites were less consistent. Collectively, these results suggest an inverse association between a history of allergy and cancer mortality; however, the strength of evidence for this association is limited.

Adult↗
PubMed2005

Changing age-pattern of hospitalisation risk of chronic obstructive pulmonary disease in men and women in Canada.

OBJECTIVE: To examine the changing pattern of age distributions of hospitalisation for chronic obstructive pulmonary disease (COPD) among Canadian men and women. DESIGN: Retrospective cohort study. PARTICIPANTS: 257,604 COPD inpatients aged 55-90 years with 463,089 hospital admissions during a 3-year study period (1994/95, 1995/96 and 1996/97) in Canada. MAIN OUTCOME MEASURES: COPD listed as one of the first five underlying diagnoses (broad definition, 463,089 hospitalisations) or as first diagnosis (narrow definition, 142,770 hospitalisations). RESULTS: Overall, men were more likely to have hospitalisations for COPD and had a higher proportion of death at hospital than did women. The 3-year cumulative incidence was 42.2/1,000 for the broadly defined COPD hospitalisation and 14.0/1,000 for the narrowly defined COPD hospitalisation, and steadily increased with increasing age. The relative risk for women versus men gradually increased with decreasing age, and was significantly greater than unity in the 55-59 year group for narrowly defined COPD hospitalisation. CONCLUSIONS: In terms of impact on secondary care COPD is a disease of the elderly and is becoming more common in women, particularly in younger age groups.

Age Distribution↗
PubMed2005

Visual motion integration in schizophrenia patients, their first-degree relatives, and patients with bipolar disorder.

Many schizophrenia patients show degraded detection of coherent motion. This visual deficit may (1) be a consequence of having a specifically schizophrenic psychosis, (2) be a non-specific effect of suffering from a severe illness (i.e., "generalized deficit"), or (3) reflect properties of the visual motion processing system that play an antecedent, possibly causal role in the pathophysiology of a disposition to schizophrenia. To distinguish among these possibilities, we measured the accuracy of detecting the direction of coherent motion in 29 schizophrenia patients, 20 first-degree relatives of schizophrenia patients, 19 patients with bipolar disorder and 33 normal controls. The task requires the integration of dynamic signals from stochastic random dot patterns in order to discern the direction of their motion. Schizophrenia patients, as a group, showed significantly elevated thresholds for detecting the direction of coherent motion, but relatives of schizophrenia patients and patients with bipolar disorder did not differ from normal controls on this task. The results indicate that visual motion integration, normally mediated in motion-sensitive brain areas such as the Middle Temporal Area, is impaired in patients with a clinically manifest schizophrenic psychosis, but is intact in patients with a non-schizophrenic psychosis (bipolar disorder) and in the relatives of schizophrenia patients. Our findings suggest that deficiencies in integrating motion signals, while specific for schizophrenia, do not seem to be a co-familial trait.

Adult↗
PubMed2005

Photosynthetic acclimation in rice leaves to free-air CO2 enrichment related to both ribulose-1,5-bisphosphate carboxylation limitation and ribulose-1,5-bisphosphate regeneration limitation.

Net photosynthetic rates (Pns) in leaves were compared between rice plants grown in ambient air control and free-air CO2 enrichment (FACE, about 200 micromol mol(-1) above ambient) treatment rings. When measured at the same CO2 concentration, the Pn of FACE leaves decreased significantly, indicating that photosynthetic acclimation to high CO2 occurs. Although stomatal conductance (Gs) in FACE leaves was markedly decreased, intercellular CO2 concentrations (Ci) were almost the same in FACE and ambient leaves, indicating that the photosynthetic acclimation is not caused by the decreased Gs. Furthermore, carboxylation efficiency and maximal Pn, both light and CO2-saturated Pn, were decreased in FACE leaves, as shown by the Pn-Ci curves. In addition, the soluble protein, Rubisco (ribulose-1,5-bisphosphate caboxylase/oxygenase), and its activase contents as well as the sucrose-phosphate synthase activity decreased significantly, while some soluble sugar, inorganic phosphate, chlorophyll and light-harvesting complex II (LHC II) contents increased in FACE leaves. It appears that the photosynthetic acclimation in rice leaves is related to both ribulose-1,5-bisphosphate (RuBP) carboxylation limitation and RuBP regeneration limitation.

Acclimatization↗
PubMed2005

Summarizing complexity in high dimensions.

High-dimensional, multispectral data on complex physical systems are increasingly common. As the amount of information in data sets increases, the difficulty of effectively utilizing it also increases. For such data, summary information is required for understanding and modeling the underlying dynamics. It is here proposed to use an extension of computational mechanics [C. R. Shalizi and J. P. Crutchfield, J. Stat. Phys. 104, 817 (2001)] to arbitrary spatiotemporal and spectral dimension, for providing such summary information. An example of the use of these tools to identify state evolution in the brain, an archetypal, complex biophysical system, serves as an illustration.

Alzheimer Disease↗
PubMed2005

Synthesis and structural identification of a highly ordered mesoporous organosilica with large cagelike pores.

Using 1,2-bis(trimethoxysilyl)ethane as organosiloxane precursor and a triblock copolymer surfactant, Pluronic F127, as template, a highly ordered mesoporous organosilica with large cagelike pores has been successfully synthesized. Its structure was resolved to be 3-D cubic Fmm by high-resolution transmission electron microscopy. The intergrowth of hexagonal close-packed and cubic close-packed phases was observed in this material. The effect of different siliceous precursors on the mesostructure was also investigated.

Ethane↗
PubMed2005

Identification of a novel glutathione adduct of diclofenac, 4'-hydroxy-2'-glutathion-deschloro-diclofenac, upon incubation with human liver microsomes.

Clinical use of the nonsteroidal anti-inflammatory drug diclofenac (DF) is associated with an incidence of idiosyncratic hepatoxicity. The formation of reactive metabolites of DF in vivo has been proposed to be responsible for such toxicity. One type of reactive metabolite, a benzoquinone imine of DF formed through oxidation by cytochromes P450, can be trapped by glutathione in vitro in liver microsomes to form glutathione (GS) adducts. Three GS adducts from DF were reported in the literature, namely, 5-hydroxy (OH)-4-glutathione-DF, 4'-OH-3'-glutathione-DF and 5-OH-6-glutathione-DF, and they all have the same molecular weight of 616. Recently, we developed a sensitive and high throughput method for the detection of GS adducts from liver microsome incubation. This method uses a constant neutral loss scan of m/z 129, a "structure-characteristic" fragment for GS adduct, on an automated chip-based nanoelectrospray (Advion NanoMate 100) attached to a tandem mass spectrometer (Sciex API 3000). The analysis of GS adducts from human liver microsome incubation with DF by the NanoMate 100-API 3000 method unambiguously revealed a new adduct ion with m/z 583 (MH+), in addition to the known adduct peak with m/z 617 (MH+). This new adduct was further confirmed to be 4'-OH-2'-glutathion-deschloro-diclofenac by liquid chromatography (LC) tandem mass spectrometry (MS), LC/MS-NMR, and comparison to a synthetic standard.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Uniformity of ionization response of structurally diverse analytes using a chip-based nanoelectrospray ionization source.

The major drawback of liquid chromatography/mass spectrometry (LC/MS) for the analysis of mixtures is the non-quantitative nature of these studies. The ionization efficiency of the various components in the mixture (e.g., a compound and its metabolites) can vary greatly and, therefore, relative intensities of signals cannot be related to relative abundance. A chip-based nanoelectrospray ionization source was used to compare the ionization efficiencies of compounds with different physical-chemical characteristics. The data indicate that the ionization efficiencies vary much less with the chip-based device than by LC/MS. This was ascribed to the generation of a much higher electric field around the nozzles, which supplies a large excess of protons to the small droplets and reduces/eliminates the differences in the ionization efficiency for the analytes.

Animals↗
PubMed2005

The association between allergy and rheumatoid arthritis in the Canadian population.

BACKGROUND: Antagonism between Th1 and Th2 lymphocyte mediated responses has been proposed to explain the observed 20th Century population increase in Th2 mediated allergic disease and reciprocal decrease in infectious disease, which stimulates a Th1 mediated response. OBJECTIVE: To determine if Th1/Th2 antagonism would be consistent with associations between non-infectious diseases, we tested the hypothesis that the population prevalence of Th2 mediated allergies is inversely related to the prevalence of Th1 mediated rheumatoid arthritis. METHODS: The analysis was based on data from the Canadian Community Health Survey conducted by Statistics Canada in 2000-2001 of those at least 12 years of age from 125,129 households. Each subject was asked if he or she had certain chronic health conditions that had been diagnosed by a health professional. Logistic regression models were used to evaluate the association between rheumatoid arthritis and allergies with consideration of other important variables. RESULTS: Allergy history was positively related to the prevalence of rheumatoid arthritis both in women (adjusted odds ratio (OR): 1.57, 95% CI: 1.43, 1.73) and in men (adjusted OR: 1.55, 95% CI: 1.36, 1.77). CONCLUSIONS: The reported population prevalences of allergies and rheumatoid arthritis were positively associated and not explained by Th1/Th2 anatagonism suggesting that this mechanism may only be applicable to the association between an infectious and an immunologic disease. Mechanisms accounting for positive associations between immunologic diseases deserve further study.

Adolescent↗