Search PubMed⌕ Search

Biomedical subjects

Y Xu

Publications and source records attributed to Y Xu.

At least 37 records · Page 2Linked to original sources
PubMed2006

A preliminary risk assessment of organochlorines accumulated in fish to the Indo-Pacific humpback dolphin (Sousa chinensis) in the Northwestern waters of Hong Kong.

The Indo-Pacific humpback dolphin is considered threatened due to several factors including pollution in Hong Kong and the risks due to consumption of fish tainted with polychlorinated biphenyls (PCBs) and organochlorine pesticides were assessed. Six species of fish Collichthys lucida, Pseudosciaena crocea, Johnius sp., Thryssa sp., Mugil sp. and Trichiurus sp., which comprise the main prey species of humpback dolphins were collected for analyses. Risks due to total PCBs, total TEQs, PCB 118 and the pesticides were assessed with the use of toxicity reference values as the threshold reference benchmarks. The calculated risk quotients (RQs) showed that the risks associated with organochlorines were generally low. The highest RQ was associated with total TEQs suggesting that dioxin-like PCBs may pose the highest risk to the dolphins. The HCHs, total PCBs and heptachlor had comparatively high RQs and thus they should also be the priority organochlorines that would require further investigation.

Animals↗
PubMed2006

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio).

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 microg l-1 for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid- reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity.

Animals↗
PubMed2006

Transcriptional profiling suggests that Barrett's metaplasia is an early intermediate stage in esophageal adenocarcinogenesis.

To investigate the relationship between Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC), we determined gene expression profiles of discrete pathological stages of esophageal neoplasia using a sequence-verified human cDNA microarray. Fifty one RNAs, comprising 24 normal esophagi (NE), 18 BEs, and nine EACs were hybridized to cDNA microarrays. Five statistical analyses were used for the data analysis. Genes showing significantly different expression levels among the three sample groups were identified. Genes were grouped into functional categories based on the Gene Ontology Consortium. Surprisingly, the expression pattern of BE was significantly more similar to EAC than to NE, notwithstanding the known histopathologic differences between BE and EAC. The pattern of NE was clearly distinct from that of EAC. Thirty-six genes were the most differentially modulated, according to these microarray data, in BE-associated neoplastic progression. Twelve genes were significantly differentially expressed in cancer-associated BE's plus EAC (as a single combined tissue group) vs noncancer-associated BE's. These genes represent potential biomarkers to diagnose EAC at its early stages. Our results demonstrate that molecular events at the transcriptional level in BE are remarkably similar to BE's-associated adenocarcinoma of the esophagus. This finding alarmingly implies that BE is biologically closer to cancer than to normal esophagus, and that the cancer risk of BE is perhaps higher than we had imagined. These findings suggest that changes modulated at the molecular biologic level supervene earlier than histologic changes, and that BE is an early intermediate stage in the process of EAC.

Adenocarcinoma↗
PubMed2006

Nuclear emissions during self-nucleated acoustic cavitation.

A unique, new stand-alone acoustic inertial confinement nuclear fusion test device was successfully tested. Experiments using four different liquid types were conducted in which bubbles were self-nucleated without the use of external neutrons. Four independent detection systems were used (i.e., a neutron track plastic detector to provide unambiguous visible records for fast neutrons, a detector, a NE-113-type liquid scintillation detector, and a NaI gamma ray detector). Statistically significant nuclear emissions were observed for deuterated benzene and acetone mixtures but not for heavy water. The measured neutron energy was <or=2.45 MeV, which is indicative of deuterium-deuterium (D-D) fusion. Neutron emission rates were in the range approximately 5x10(3) n/s to approximately 10(4) n/s and followed the inverse law dependence with distance. Control experiments did not result in statistically significant neutron or gamma ray emissions.

Journal Article↗
PubMed2006

Transmission disequilibrium test provides evidence of association between promoter polymorphisms in 22q11 gene DGCR14 and schizophrenia.

Recent research has suggested that the DiGeorge syndrome critical region gene 14 (DGCR14) exhibits activity differences of more than 1.5 fold between the haplotypes of the variants in the promoter region. DGCR14 is located at 22q11.21, an acknowledged region for susceptibility to schizophrenia. To test the hypothesis that DGCR14 may be involved in the etiology of the disease, we carried out a family-based association study between the reported functional markers and schizophrenia in 235 Chinese Han trios. We found significant evidence of preferential transmission of the promoter variants of DGCR14 across all the trios (Best p-value = 0.00038, Global p-value = 0.0008). The positive results have suggested that DGCR14 is likely to play an important role in the etiology of schizophrenia in the Chinese Han population.

Adult↗
PubMed2006

Dopamine-D1 and -D2 receptors differentially regulate synapsin II expression in the rat brain.

We previously demonstrated that chronic treatment with the dopamine-D2 receptor antagonist, haloperidol, increases mRNA and protein content of the phosphoprotein, synapsin II, in the rat striatum. Since dopamine-D2 receptor antagonism and dopamine-D1 receptor blockade can have opposing effects on gene expression, the present investigation compared the effects of haloperidol with those of the dopamine-D1 receptor antagonist, R-[+]-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH23390), on the expression of synapsin II protein. Haloperidol and SCH23390 respectively elevated and reduced concentrations of the molecule in mouse primary midbrain cell cultures. Additional experiments revealed that the dopamine-D1 receptor agonist, R-[+]-1-phenyl-2,3,4,5-tetrahydro-(1H)-3-benzapezine-7,8-diol (SKF38393), upregulated the phosphoprotein in these cells. Furthermore, in vivo rat studies demonstrated that chronic haloperidol treatment increases synapsin II protein expression in the medial prefrontal cortex and nucleus accumbens, as was observed in the striatum. In contrast, chronic SCH23390 administration reduced concentrations of this protein in all of these regions, although the reductions seen in the medial prefrontal cortex were insignificant. Neither haloperidol nor the dopamine-D1 receptor antagonist affected synapsin I protein expression in any of the studied brain areas. Based on these findings, we propose dopamine receptors may specifically regulate synapsin II expression through a cyclic AMP-dependent pathway. Since synapsin II is involved in neurotransmitter release and synaptogenesis, and changes in synaptic efficacy and structure are suggested in schizophrenia as well as in haloperidol treatment, our findings offer insight into the mechanistic actions of the antipsychotic agent at the synaptic level.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2006

Preclinical assessment of the feasibility of applying controlled release oral drug delivery to a lead series of atypical antipsychotics.

In this paper, we present a preclinical approach for evaluating the feasibility of applying controlled-release (CR) oral drug delivery to increase the duration of exposure and lower the C(max) of compounds in a lead series of short half-life atypical antipsychotics. Three lead compounds in the series had demonstrated potential pharmacological benefits for the treatment of psychosis, in preclinical studies. However, the compounds showed evidence of insufficient half-lives to enable a once-a-day (QD) product using immediate-release (IR) oral delivery. To evaluate and compare the potential for oral CR delivery to extend the duration of action and thereby enable QD administration, the in vitro solubility and permeability, and the duodenal and colonic absorption of three compounds in the series were measured. Based on the results, one candidate was selected for advancement that showed moderate in vitro solubility, but had the highest in vitro permeability and ratio of colonic to duodenal bioavailability (0.9) in the rat. The results from this study provided evidence that a CR drug delivery system could be used to extend the duration of exposure of the compounds in the series and a scientific basis for selecting one of the three compounds as a candidate.

Administration, Oral↗
PubMed2006

Methylenetetrahydrofolate reductase gene polymorphism, homocysteine and risk of macroangiopathy in Type 2 diabetes mellitus.

OBJECTIVE: A polymorphism in the gene for methylenetetrahydrofolate reductase (MTHFR) has been reported to be associated with hyperhomocysteinemia and risk for atherosclerotic vascular diseases. In this case-control study, we examined the distribution of the MTHFR genotypes in the Chinese population and clarified the relationship between the gene polymorphism for MTHFR and macroangiopathy in Chinese Type 2 diabetes mellitus. METHODS: Two hundred and sixteen unrelated patients with Type 2 diabetes mellitus, 112 of whom had macroangiopathy, and 114 healthy control subjects, were recruited. The MTHFR C677T genotype was analyzed by polymerase chain reaction-restriction fragment length polymorphism. Plasma total homocysteine levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. RESULTS: In 114 healthy control subjects, the frequency of the mutant T allele was 31.1%. The genotype distribution did not differ between control subjects and Type 2 diabetic patients (chi2=3.03, p=0.220). Genotypic analysis revealed that the MTHFR genotype was different between diabetic patients with and without macroangiopathy (chi2=12.42, p=0.002). Type 2 diabetic patients with macroangiopathy displayed a greater prevalence of T allele than Type 2 diabetic patients without macroangiopathy (44.6 vs 29.3%; chi2=10.82, p=0.001). The odds ratio for macroangiopathy in Type 2 diabetic patients in presence of T allele was 1.94 [confidence interval (CI) 95%: 1.31-2.89]. Moreover, plasma homocysteine levels were markedly higher in individuals with TT genotype than those with CC or CT genotype. CONCLUSIONS: The C677T mutation of MTHFR gene is common in the Chinese population. MTHFR C677T gene polymorphism associated with a predisposition to increased plasma homocysteine levels could constitute a useful predictive marker for macroangiopathy in Chinese Type 2 diabetic patients.

Case-Control Studies↗
PubMed2006

Expression of Eph receptor tyrosine kinases and their ligands in human Granulosa lutein cells and human umbilical vein endothelial cells.

Corpus luteum development is regulated by gonadotropins and accompanied by extremely rapid vascularization of the avascular granulosa cell compartiment by endothelial cells (EC). The proliferation of Granulosa cells (GC) and EC is a complex interplay and takes place in a spatially and temporarily coordinated manner. The erythropoietin-producing hepatoma amplified sequence (Eph) receptors and their ligands-the ephrins- are a recently detected family of membrane located protein tyrosine kinases which play a crucial role in the growth and development of nerve and blood vessel network. We report about the mRNA expression pattern of Ephs and their ligands in human GC, in human EC, and in carcinoma cell lines OvCar-3 and Hela. The mRNA of EphA4, EphA7, ephrinA4, ephrinB1 and ephrinB2 was detected in GC and EC, while EphA2 was expressed only in GC. The expression of various Ephs and ephrins did not change in GC after stimulation with human chorion gonadotropin. Our study analyzes for the first time the expression of the complete human Eph/ephriny-system in GC and in EC. The remarkable similarity between these two cell types supports the theory of a functional relationship of EC and GC. In addition, it was shown that hCG is not a major determinant of Eph/ephrin regulation in GC.

Cell Separation↗
PubMed2006

Combination of antagonistic yeasts with two food additives for control of brown rot caused by Monilinia fructicola on sweet cherry fruit.

AIMS: To evaluate beneficial effect of two food additives, ammonium molybdate (NH4-Mo) and sodium bicarbonate (NaBi), on antagonistic yeasts for control of brown rot caused by Monilinia fructicola in sweet cherry fruit under various storage conditions. The mechanisms of action by which food additives enhance the efficacy of antagonistic yeasts were also evaluated. METHODS AND RESULTS: Biocontrol activity of Pichia membranefaciens and Cryptococcus laurentii against brown rot in sweet cherry fruit was improved by addition of 5 mmol l(-1) NH4-Mo or 2% NaBi when stored in air at 20 and 0 degrees C, and in controlled atmosphere (CA) storage with 10% O2 + 10% CO2 at 0 degrees C. Population dynamics of P. membranefaciens in the wounds of fruit were inhibited by NH4-Mo at 20 degrees C after 1 day of incubation and growth of C. laurentii was inhibited by NH4-Mo at 0 degrees C in CA storage after 60 days. In contrast, NaBi did not significantly influence growth of the two yeasts in fruit wounds under various storage conditions except that the growth of P. membranefaciens was stimulated after storage for 45 days at 0 degrees C in CA storage. When used alone, the two additives showed effective control of brown rot in sweet cherry fruit and the efficacy was closely correlated with the concentrations used. The result of in vitro indicated that growth of M. fructicola was significantly inhibited by NH4-Mo and NaBi. CONCLUSION: Application of additives improved biocontrol of brown rot on sweet cherry fruit under various storage conditions. It is postulated that the enhancement of disease control is directly because of the inhibitory effects of additives on pathogen growth, and indirectly because of the relatively little influence of additives on the growth of antagonistic yeasts. SIGNIFICANCE AND IMPACT OF THE STUDY: The results obtained in this study suggest that an integration of NH4-Mo or NaBi with biocontrol agents has great potential in commercial management of postharvest diseases of fruit.

Ascomycota↗
PubMed2006

Chimaeric protein improved immunogenicity compared with fusion protein of Ag85B and ESAT-6 antigens of Mycobacterium tuberculosis.

Antigen 85B (Ag85B) and ESAT-6 are important immunodominant antigens of Mycobacterium tuberculosis, and both are very promising vaccine candidate molecules. In this study, we relied on the T-cell epitopes of Ag85B and ESAT-6 to design a chimaeric protein by inserting ESAT-6 into Ag85B from the amino acids 167-182. We found the ratio of IgG2b/IgG1 and the secretion of interferon (IFN)-gamma in the mice vaccinated with the new protein with adjuvant MPL and TDM were higher than the mice immunized with fusion protein Ag85B-ESAT-6, which have been reported and could induce levels of protective immunity similar to BCG in the mouse model of tuberculosis (TB) infection. These results suggest that the chimaeric protein Ag85B(N)-ESAT-6-Ag85B(C) is a strong candidate for further study and the T-cell epitopes of the antigens should be considered when we design the subunit vaccine.

Acyltransferases↗
PubMed2006

Three-dimensional dose verification for intensity modulated radiation therapy using optical CT based polymer gel dosimetry.

Dose distributions generated from intensity-modulated-radiation-therapy (IMRT) treatment planning present high dose gradient regions in the boundaries between the target and the surrounding critical organs. Dose accuracy in these areas can be critical, and may affect the treatment. With the increasing use of IMRT in radiotherapy, there is an increased need for a dosimeter that allows for accurate determination of three-dimensional (3D) dose distributions with high spatial resolution. In this study, polymer gel dosimetry and an optical CT scanner have been employed to implement 3D dose verification for IMRT. A plastic cylinder of 17 cm diameter and 12 cm height, filled with BANG3 polymer gels (MGS Research, Inc., Madison, CT) and modified to optimal dose-response characteristics, was used for IMRT dose verification. The cylindrical gel phantom was immersed in a 24 x 24 x 20 cm water tank for an IMRT irradiation. The irradiated gel sample was then scanned with an optical CT scanner (MGS Research Inc., Madison, CT) utilizing a single He-Ne laser beam and a single photodiode detector. Similar to the x-ray CT process, filtered back-projection was used to reconstruct the 3D dose distribution. The dose distributions measured from the gel were compared with those from the IMRT treatment planning system. For comparative dosimetry, a solid water phantom of 24 x 24 x 20 cm, having the same geometry as the water tank for the gel phantom, was used for EDR2 film and ion chamber measurements. Root mean square (rms) deviations for both dose difference and distance-to-agreement (DTA) were used in three-dimensional analysis of the dose distribution comparison between treatment planning calculations and the gel measurement. Comparison of planar dose distributions among gel dosimeter, film, and the treatment planning system showed that the isodose lines were in good agreement on selected planes in axial, coronal, and sagittal orientations. Absolute point-dose verification was performed with ion chamber measurements at four different points, varying from 48% to 110% of the prescribed dose. The measured and calculated doses were found to agree to within 4.2% at all measurement points. For the comparison between the gel measurement and treatment planning calculations, rms deviations were 2%-6% for dose difference and 1-3 mm for DTA, at 60%-110% doses levels. The results from this study show that optical CT based polymer gel dosimetry has the potential to provide a high resolution, accurate, three-dimensional tool for IMRT dose distribution verification.

Algorithms↗
PubMed2006

Renal replacement lipomatosis.

We report a relatively rare case of renal replacement lipomatosis presenting as a renal mass. Computed tomography revealed a predominantly low-density and roundish mass, with an irregular renal parenchyma, high-density calcification, and abundant low-density fat. The differential diagnosis before surgery was squamous cell carcinoma, teratoma, or angiomyolipoma of the kidney. The case was initially misdiagnosed, because we had no experience with this disease. After mass exploration, histological examination confirmed the diagnosis of renal replacement lipomatosis. The patient was free from signs of recurrence 10 months after the operation.

Female↗
PubMed2006

Variables which might predict the response to salvage radiotherapy in chinese patients with biochemical failure after radical prostatectomy.

BACKGROUND/AIMS: To evaluate the relationship between the variables and the outcomes of salvage radiotherapy (sRT) to find some predictors of sRT. METHODS: The medical records of 56 patients receiving sRT for biochemical failure after radical prostatectomy (RP) were available for retrospective review. sRT was defined as external beam radiotherapy for patients with a continuous increase in the prostate-specific antigen (PSA) level of >or=0.2 ng/ml after RP. Response was defined as achievement of a PSA nadir of 6 months were all responders. The response rate in patients with seminal vesicle invasion was 42.9% (6/14) versus 76.2% (32/42) in patients without seminal vesicle invasion (OR=0.119, p=0.015). CONCLUSION: PSADT and the state of seminal vesicle invasion were good predictors of response to sRT. sRT was especially effective when the PSADT was >6 months and in patients without seminal vesicle invasion.

China↗
PubMed2006

Application of uncertainty and sensitivity analysis in river basin management.

Considering uncertainty in the decision-making process in river basin management is important because uncertainty is regarded as one of the main obstacles to sound decision-making. In case of high uncertainty, the risks of making a wrong decision could be quite high, which may have severe consequences. This paper applies a screening sensitivity analysis method, the Morris method, to investigate the propagation of uncertainty from factors in a flood damage model into the model outputs and explores the importance of factors based on the sensitivity analysis. Uncertainty reduction in the most influential factors identified by the Morris method is proposed as a means to reduce the uncertainty in model outputs. In this way the risks of making a wrong decision could be reduced. The results in this paper show that the Morris method is an efficient approach to help reduce the uncertainty in model outputs.

Conservation of Natural Resources↗
PubMed2006

Removal of boron (B) from waste liquors.

This paper explores the use of electrocoagulation to remove boron from waste effluent in comparison with alum coagulation. In treating model test wastes, greater boron removals were achieved with electrocoagulation at low doses than conventional alum coagulation when reaction was undertaken for the same conditions (pH 8.5, and initial boron concentration was 500 mg/L). Al electrocoagulation can achieve good boron removal performance (68.3%) at a dose of 2.1 (as molar ratio of Al:B, and for current density of 62.1 A/m2), while alum coagulation can only achieve the maximum boron removal of 56% at a dose of 2.4. Also, Al electrocoagulation can remove 15-20% more boron than alum coagulation for the same dose compared in the treatment of both model test wastes and industry effluent. The estimation of running costs shows that to achieve 75% boron removal from industry waste effluent, i.e. removing 150 g of boron from 1 m3 of effluent, electrocoagulation was 6.2 times cheaper than alum coagulation. The economic advantage of electrocoagulation in the treatment of boron-containing waste effluent is thus significant.

Alum Compounds↗
PubMed2005

The distance to the Perseus spiral arm in the Milky Way.

We have measured the distance to the massive star-forming region W3OH in the Perseus spiral arm of the Milky Way to be 1.95 +/- 0.04 kiloparsecs (5.86 x10(16) km). This distance was determined by triangulation, with Earth's orbit as one segment of a triangle, using the Very Long Baseline Array. This resolves the long-standing problem that there is a discrepancy of a factor of 2 between different techniques used to determine distances. The reason for the discrepancy is that this portion of the Perseus arm has anomalous motions. The orientation of the anomalous motion agrees with spiral density-wave theory, but the magnitude of the motion is somewhat larger than most models predict.

Journal Article↗