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Biomedical subjects

Y Zhang

Publications and source records attributed to Y Zhang.

At least 127 records · Page 7Linked to original sources
PubMed2005

Glutathione S-transferase polymorphisms and ovarian cancer treatment and survival.

OBJECTIVE: Members of the glutathione S-transferase (GST) family have been shown to have functional polymorphisms that may affect drug metabolism and influence the effects of chemotherapy and survival from cancer. GSTM1, GSTT1, and GSTP1 genotypes were evaluated for their role in ovarian cancer treatment and survival. METHODS: DNA was extracted from tumor tissues of 215 patients diagnosed with primary epithelial ovarian cancer. GSTM1 and GSTT1 genotypes were determined by multiplex PCR; GSTP1 genotypes were assessed with PCR-RFLP. Associations between GST polymorphisms and risk of ovarian cancer progression or death were analyzed using Cox proportional hazards regression; subgroups of patients receiving different chemotherapeutics were also evaluated. RESULTS: GST polymorphisms were not found to be associated with patient or tumor characteristics or response to treatment. However, GSTM1 null patients were less likely to have disease progression (HR: 0.65, 95% CI: 0.43-0.99) or to die (HR: 0.68, 95% CI: 0.45-1.03) compared to patients with GSTM1. Patients with GSTM1 null and GSTP1 ile/val or val/val (reduced function) had a further reduction in risk of disease progression compared to patients with GSTM1 or GSTP1 ile/ile (HR: 0.42, 95% CI: 0.24-0.75). A similar association was also suggested for overall survival (HR: 0.61, 95% CI: 0.36-1.05). Subgroup analyses indicated that the effects of GST on survival were more pronounced among patients treated with specific chemotherapeutics. CONCLUSION: These findings support the idea that reduced GST function may improve ovarian cancer survival after post-operative chemotherapy; evaluation of GST functional polymorphisms may help to predict ovarian cancer prognosis.

Adult↗
PubMed2005

Maxillofacial Injury Severity Score: proposal of a new scoring system.

In this study a new injury severity score system, the Maxillofacial Injury Severity Score (MFISS), was developed to evaluate the characteristics of injury from maxillofacial trauma. Nine hundred and two cases of maxillofacial trauma were included in this study to evaluate injury severity using the MFISS, which was designed on the basis of Abbreviated Injury Scale, 1990 revision (AIS-90), and defined as the product of the sum of the three highest maxillofacial AIS scores and the sum of the injury severity scores for three maxillofacial functional parameters, malocclusion (MO), limited mouth opening (LMO), and facial deformity (FD). The correlation analysis was undertaken with the dependent factor of cost and number of days of stay in hospital. The results demonstrated a significant difference (P < 0.01) between bone and soft-tissue injuries and among various regional fractures. There was correlation (P < 0.01) between the MFISS and the cost of treatment and days of stay in hospital. The newly established MFISS thus characterizes maxillofacial injury severity while reflecting the management costs and treatment complexity.

Adolescent↗
PubMed2005

Trapeziometacarpal subluxation predisposes to incident trapeziometacarpal osteoarthritis (OA): the Framingham Study.

OBJECTIVE: Osteoarthritis (OA) of the thumb carpo-metacarpal joint is a common condition that can lead to substantial pain, instability, deformity, and loss of motion. It has been hypothesized that instability of the trapeziometacarpal joint combined with strenuous use can potentially lead to OA. However, as yet there have been no longitudinal evaluations to determine if this hypothesis is true. We examined the relation of radial subluxation to the risk of radiographic OA at trapeziometacarpal joint. METHODS: We conducted a nested case-control study. We restricted our evaluation of cases to subjects with no radiographic trapeziometacarpal OA at baseline (1967). We defined incident trapeziometacarpal OA as the development of a modified Kellgren and Lawrence grade>or=2 in that joint at a later examination (1992-1993). Radial subluxation of the base of the first metacarpal off the trapezium and the amount of the base of the first metacarpal covering the articulating surface of the trapezium were measured using a digital calculation caliper. We examined the relation of gender-specific quartile groups of radial subluxation to the risk of trapeziometacarpal OA using a conditional logistic regression model. RESULTS: We assessed 203 men and 431 women. After adjusting for age, handedness, number of other joints with OA, and grip strength, the odds ratios for the risk of trapeziometacarpal OA in men were 1.0, 1.8, 2.7, and 3.1 from the lowest quartile of radial subluxation to the highest quartile, respectively (P for trend=0.015). There was no significant relationship between radial subluxation quartiles and incident trapeziometacarpal OA in women. CONCLUSION: This study provides evidence that radial subluxation predisposes to subsequent OA of the trapeziometacarpal joint in men.

Adult↗
PubMed2005

TSPY is a cancer testis antigen expressed in human hepatocellular carcinoma.

In search for genes associated with hepatocellular carcinoma (HCC) by cDNA microarray, we found that the transcription of TSPY, 'testis-specific protein Y-encoded', was upregulated in HCC. Investigation of a broad spectrum of normal and malignant tissues by RT-PCR revealed the TSPY transcript selectively expressed in normal testis, different histological types of human neoplastic tissues, and tumour cell lines. The expression of TSPY in cancer cells was further confirmed by in situ hybridisation. Indirect immunofluorescence microscopy analysis showed that TSPY was localised mainly in the cytoplasm of transiently transfected cells. Testis-specific protein Y-encoded was detected in 50% (16 of 32) of well- and moderately differentiated HCC patients, in 16% (four of 25) of poorly differentiated HCC patients, and in 5% (one of 19) of renal cell cancer patients. A serological survey revealed that 6.6% (seven of 106) HCC patients had anti-TSPY antibody response, demonstrating the immunogenicity of TSPY in humans. In conclusion, these data suggest that TSPY is a novel cancer/testis (CT) antigen and may be a potential candidate in vaccine strategy for immunotherapy in HCC patients.

Antigens, Neoplasm↗
PubMed2005

Degradation of methyl isothiocyanate and chloropicrin in forest nursery soils.

Recent studies have observed enhanced degradation of methyl isothiocyanate (MITC) from repeated fumigation in agricultural soils. Little is known about fumigant degradation in forest and nursery soils. This study was conducted to determine degradation rates of MITC and chloropicrin (CP) in two forest soils and the impacts of nursery management on degradation of MITC and CP. The half-life values of MITC and CP were evaluated in the laboratory under isothermal conditions (22 +/- 2 degrees C). Three rates representing 0.5x, 1x, and 2x field application rates for each fumigant were used in laboratory incubations. Effect of microbial degradation was determined by conducting incubations with both fresh and sterilized soils. Soil moisture effects were also studied. There was no difference in MITC or CP degradation between fumigated and nonfumigated forest nursery soils. Soil sterilization and high soil moisture content (15% by wt.) reduced MITC and CP degradation. The degradation rates of MITC and CP varied with factors such as nursery history, fumigant application rates, and freshness of tested soils.

Biodegradation, Environmental↗
PubMed2005

Colloidal rings in a liquid mixture.

We investigate the self-assembly of colloidal particles on microscopic decane droplets in water and show that, by use of paramagnetic colloids, it is possible to assemble ringlike structures that can be controlled with a magnetic field. Moreover, the use of paramagnetic colloids allows us to determine the attractive forces between the colloids located at the three-phase contact line between decane, water, and air. The attractive force is in the femtonewton range and is attributed to capillary interactions due to interface deformations. When the liquid emulsion dries on a glass slide, we observe solid deposits in the form of microscopic rings of varying diameters.

Journal Article↗
PubMed2005

Measurement of the D(s)+ lifetime.

A high statistics measurement of the D(s)+ lifetime from the Fermilab fixed-target FOCUS photoproduction experiment is presented. We describe the analysis of the two decay modes, D(s)+ --> phi(1020)pi+ and D(s)+ -->K*(892)0K+, used for the measurement. The measured lifetime is 507.4 +/- 5.5(stat) +/- 5.1(syst) fs using 8961 +/- 105 D(s)+ --> phi(1020)pi+ and 4680 +/- 90 D(s)+ --> K*(892)0K+ decays. This is a significant improvement over the present world average.

Journal Article↗
PubMed2005

In vitro expression and analysis of secreted fowlpox virus CC chemokine-like proteins Fpv060, Fpv061, Fpv116 and Fpv121.

The four CC chemokine-like proteins (Fpv060, Fpv061, Fpv116 and Fpv121) of fowlpox virus (FWPV) were over-expressed as His-tagged versions from a T7 promoter/EMCV IRES construct in vitro, by coupled transcription/translation, or in cell culture, by co-infection with two recombinant FWPVs (one expressing the chemokine-like protein and one expressing T7 RNA polymerase). All, except Fpv116, appeared to be glycosylated in the presence of microsomal membranes in vitro. In culture, all were secreted (even though secretion of Fpv061 was not predicted). Secreted forms of Fpv060 and Fpv121 were the most abundant forms of those two proteins. Glycosidase analysis of cellular and secreted forms confirmed that Fpv060, Fpv061 and Fpv121 were N-glycosylated and that the most abundant, cellular form of Fpv061 had been glycosylated but remained Endo H-sensitive (retained in the endoplasmic reticulum or Golgi). N-terminal sequence analysis of His-tagged Fpv060 and Fpv121 showed that they were processed at the predicted signal cleavage sites. Fpv060- and Fpv061-specific antipeptide sera allowed confirmation that the expression, processing and secretion of the native proteins were as determined for the His-tagged proteins. Isolation of knock-out mutants showed that all four proteins were non-essential for replication in tissue culture.

Amino Acid Sequence↗
PubMed2005

Quantitative relationship between functionally active telomerase and major telomerase components (hTERT and hTR) in acute leukaemia cells.

Functionally active telomerase is affected at various steps including transcriptional and post-transcriptional levels of major telomerase components (hTR and human telomerase reverse transcriptase (hTERT)). We therefore developed a rapid and sensitive method to quantify hTERT and its splicing variants as well as the hTR by a Taqman real-time reverse transcriptase-polymerase chain reaction to determine whether their altered expression may contribute to telomere attrition in vivo or not. Fresh leukaemia cells obtained from 38 consecutive patients were used in this study. The enzymatic level of telomerase activity measured by TRAP assay was generally associated with the copy numbers of full-length hTERT+alpha+beta mRNA (P=0.0024), but did not correlate with hTR expression (P=0.6753). In spite of high copy numbers of full-length hTERT mRNA, telomerase activity was low in some cases correlating with low copy numbers of hTR, raising the possibility that alteration of the hTR : hTERT ratio may affect functionally active telomerase activity in vivo. The spliced nonactive hTERT mRNA tends to be lower in patients with high telomerase activity, suggesting that this epiphenomenon may play some role in telomerase regulation. An understanding of the complexities of telomerase gene regulation in biologically heterogeneous leukaemia cells may offer new therapeutic approaches to the treatment of acute leukaemia.

Adolescent↗
PubMed2005

Gene discovery and expression profiling in porcine Peyer's patch.

Peyer's patches of the intestinal mucosa are essential for host defense and immune regulation in the enteric system. To better understand molecular mechanisms of Peyer's patch function, we have screened for differentially expressed genes specific to Peyer's patch. cDNA libraries were created from normal Peyer's patch, immune stimulated Peyer's patch, and pooled cDNA subtracted with fibroblast RNA. From the subtracted library, 3687 expressed sequence tags (ESTs), representing 2414 unique nucleotide sequences, were isolated, identified by BLAST searches against public databases, and spotted onto a microarray for gene expression profiling. Approximately 30% of these ESTs BLAST to genes of unknown function and 20% have no known homology in the public databases (novel genes). Of the novel genes, 70% are expressed in normal immune tissues by microarray analysis, suggesting that at least 371 of the unidentified EST sequences from the subtracted library are novel porcine genes and can now be further characterized to determine their function in the porcine Peyer's patch. We surmise that the products of these genes participate in biochemical and cellular functions related to the unique immunological and gastroenterological functions of the small intestine. The BLAST and gene ontology information for each of the subtracted library EST sequences, the normal and immune stimulated libraries, and the microarray are all valuable resources that will facilitate further examination of the biological function of porcine Peyer's patch tissue.

Animals↗
PubMed2005

Effect of petroleum-containing wastewater irrigation on bacterial diversities and enzymatic activities in a paddy soil irrigation area.

Effects of petroleum contamination on bacterial diversities and enzymatic activities in paddy soils were investigated in the Shenfu irrigation area, the largest area irrigated by oil-containing wastewater for more than 50 yr in northeastern China. Bacterial diversities were determined by conventional colony morphology typing techniques and 16S rDNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Dehydrogenase, hydrogen peroxidase, polyphenol oxidase, urease, and substrate-induced respiration (SIR) were measured to evaluate the effects of petroleum-containing wastewater irrigation on soil biochemical characteristics. Results showed that paddy soil total petroleum hydrocarbon (TPH) concentration in the irrigation area varied from 277.11 to 5213.37 mg kg(-1) dry soil. Soil TPH concentration declined along the gradient of the irrigation channel from up- to downstream. At the current pollution level, the paddy soil TPH concentration was positively correlated with the colony forming units (CFU) of aerobic heterotrophic bacteria (AHB) (r = 0.928, p < 0.001) and the genetic diversity based on DGGE profiles (r = 0.655, p < 0.05). The bacterial diversities in the soils based on colony morphotypes of AHB also increased with TPH concentration (r = 0.598), but not significant statistically (p = 0.052). Analysis of soil enzyme activities indicated a significant positive correlation between soil TPH concentration and activities of dehydrogenases (r = 0.974, p < 0.001), hydrogen peroxidases (r = 0.957, p < 0.001), polyphenol oxidases (r = 0.886, p < 0.001), and SIR (r = 0.916, p < 0.001). On the contrary, the urease activity showed a negative correlation with paddy soil TPH concentration (r = -0.814, p = 0.002), and could be used as a sensitive indicator of petroleum contamination.

Agriculture↗
PubMed2005

Maternal hormone levels among populations at high and low risk of testicular germ cell cancer.

Ethnic differences in maternal oestrogen levels have been suggested as explaining the significantly higher risk of testicular germ cell tumours (TGCT) of white men than black men in the United States. We therefore examined levels of maternal oestrogens, as well as testosterone and alphafetoprotein (AFP), in 150 black and 150 white mothers in the Collaborative Perinatal Project. Serum levels of estradiol (total, free and bioavailable), estriol, testosterone (total, free and bioavailable), sex hormone binding globulin (SHBG), and AFP were examined during first and third trimesters. We found that the black mothers, rather than the white mothers, had significantly higher estradiol levels in first trimester (P=0.05). Black mothers also had significantly higher levels of all testosterone (P<0.001) and AFP (P<0.001) in both trimesters. In addition, the ratios of sex hormones (estradiol/testosterone) were significantly lower among black mothers. These findings provide little support to the oestrogen hypothesis, but are consistent with higher levels of testosterones and/or AFP being associated with reduced risk of TGCT; alternatively, lower oestrogen/androgen ratios may be associated with reduced risk.

Adult↗
PubMed2005

Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)-g-poly(vinylpyrrolidone): association behavior in aqueous solution and interaction with anionic surfactants.

In this work, we aimed to study the association and interaction behavior of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) block copolymers grafted with poly(vinylpyrrolidone). Critical micellization concentrations were determined using fluorescent probes (pyrene) and critical micellization temperatures characterizing temperature-dependent transitions from monomers to multimolecular micelles were measured. The thermal responsiveness of the copolymer is not affected by the grafting. The hydrodynamic radius of the graft copolymer micelles is found to be greater than that of the original copolymer micelles. The graft copolymer is found to form anisotropic aggregates. The structure of the graft copolymer micelles is less disrupted by the anionic surfactant sodium dodecyl sulfate, compared to the ungraft copolymer.

Journal Article↗
PubMed2005

Leptin resistance exacerbates diet-induced obesity and is associated with diminished maximal leptin signalling capacity in rats.

AIMS/HYPOTHESIS: Leptin resistance is generally considered a consequence of obesity. We postulated that leptin resistance is associated with diminished hypothalamic leptin signalling capacity and that leptin resistance is causal to obesity. We assessed maximal leptin-mediated binding of the transcription factor signal transducer and activator of transcription 3 (STAT3), and the response to high-fat feeding in lean leptin-resistant rats. MATERIALS AND METHODS: Recombinant adeno-associated virus encoding rat leptin cDNA (rAAV-leptin) or control vector were administered by intracerebroventricular injection to lean F344 x BN rats for up to 150 days, and food consumption, body weight, serum leptin and glucose tolerance were measured. Leptin-mediated hypothalamic transcription factor binding was assessed at day 150 following an intracerebroventricular injection of 2 mug leptin. Rats pretreated with either control or rAAV-leptin vector for 94 days were given a high-fat diet, and energy intake, body weight gain and adiposity were examined. RESULTS: The rAAV-leptin-treated rats initially responded to leptin gene delivery then became leptin-resistant. They displayed persistent submaximal hypothalamic leptin signalling and enhanced insulin sensitivity, yet maximal hypothalamic signalling capacity was decreased by more than 50%. On a high-fat diet, the leptin-resistant rats consumed more energy, gained more weight and accumulated greater visceral fat mass than controls. CONCLUSIONS/INTERPRETATION: The maximal hypothalamic leptin signalling capacity was diminished in leptin-resistant rats receiving central rAAV-leptin gene therapy. Moreover, this leptin-invoked leptin resistance perturbs the regulation of energy homeostasis in response to high fat exposure, producing augmented energy consumption. This, coupled with potential hypersensitivity to insulin, creates a milieu favouring fat deposition. Our data suggest that leptin resistance is both a consequence and cause of obesity.

Animals↗
PubMed2005

In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms.

The estrogenic activity of 70% EtOH extracts of 32 traditional Chinese medicinal plants, selected according to their reported efficacy for the treatment of menopausal symptoms, was assessed using a recombinant yeast system with both a human estrogen receptor expression plasmid and a reporter plasmid. Among them, 11 (34%) species proved to be active. Polygonum cuspidatum had the highest estrogenic relative potency (RP) (3.28 x 10(-3)), followed by Rheumpalmatum (3.85 x 10(-4)), Cassia obtusifolia (3.49 x 10(-4)), Polygonum multiflorum (2.87 x 10(-4)), Epimedium brevicornum (2.30 x 10(-4)), Psoralea corylifolia (1.90 x 10(-4)), Cynomorium songaricum (1.78 x 10(-4)), Belamcanda chinensis (1.26 x 10(-4)), Scutellaria baicalensis (8.77 x 10(-5)), Astragalus membranaceus (8.47 x 10(-5)) and Pueraria lobata (6.17 x 10(-5)). The EC(50) value of 17beta-estradiol used as the positive control was 0.205+/-0.025 ng/ml (RP=100). This study gave support to the reported efficacy of Chinese medicines used for hormone replacement therapy.

Female↗
PubMed2005

Changes in the index of sweat ion concentration with increasing sweat during passive heat stress in humans.

To investigate the pattern changes in the index of sweat ion concentration at skin surface with increasing sweat during passive heat stress in humans, we measured conductivity of the perfused water with sweat as the index of sweat ion concentration and sweat rate, continuously at the chest skin surface. Eight healthy subjects (22.4 +/-1.0 years) were passively heated by lower-leg immersion in a hot water bath of 42 degrees C for 50 min in an ambient temperature of 28 degrees C and relative humidity of 50%. The internal temperature (Tor) thresholds of sweat rate and index of sweat ion concentration were almost similar. Concomitant onset for the index of sweat ion concentration and sweat rate occurred but two types of linear regression lines were identified in the relationship between the index of sweat ion concentration and sweat rate at a boundary sweat rate value of 0.30 +/- 0.08 mg cm(-2) min(-1). The slope of the regression line at low levels of sweat (slope 0.02 +/- 0.01 V mg(-1) cm(-2) min(-1)) was significantly gradual compared with that at moderate levels of sweat (slope 0.30 +/- 0.08 V mg(-1) cm(-2) min(-1)) (P<0.05). These results suggest that at low levels of sweat the index of sweat ion concentration responds gradually with respect to sweat rate, which may be due to the ion reabsorption capacity of the sweat duct, and then the index of sweat ion concentration increased steeply with sweat rate.

Adult↗
PubMed2005

Characterization of human primary enamel organ epithelial cells in vitro.

UNLABELLED: Tooth enamel is formed by ameloblasts, which are derived from the epithelial cells of the enamel organ. OBJECTIVE: The purpose of this study was to grow human ameloblast-like epithelial cells in culture. DESIGN: Human fetal tooth organs were isolated, and the cells were separated by digestion in collagenase/dispase. The cells were cultured in KGM-2 media with and without serum and at different calcium concentrations. The expression of enamel matrix proteins was analyzed by RT-PCR and cytokeratin 14 was detected by immunohistochemistry. The cells were further characterized by osteogenesis/odontogenesis-related DNA array. RESULTS: Cells isolated from the tooth organs grown in KGM-2 media containing 2-10% serum, were mixture of cobblestone and spindle shaped cells. Culturing these cells in KGM-2 with 0.05 mM calcium was selective for cobblestone ameloblasts-like cells (CAB), which were immunopositive for cytokeratin 14. Amelogenin, ameloblastin, enamelin, MMP-20 and KLK-4 were detected in CAB cells by RT-PCR. Osteogenesis SuperArray analyses could not detect the presence of typical molecules related to mesenchymal odontoblast or osteoblast lineage cells in these cultures. CONCLUSIONS: These studies showed that cobblestone-shaped ameloblast-like cells are selected from the tooth organ cells, by culture in KGM-2 media with 0.05 mM calcium.

Ameloblasts↗