Biomedical subjects

Zhuo Yu

Publications and source records attributed to Zhuo Yu.

7 recordsLinked to original sources

PubMed2005

[Influence on the cytokines expression on hepatic tissue by inhibition the signal pathway of inflammatory mediators following extensive hepatectomy in rats].

OBJECTIVE: To investigate the impact of AG490, a cytokine signaling inhibitor, on cytokine signaling pathway with phosphorylation levels of Janus kinase 2 (Jak2) and singal transducers and activators of transcription 3 (Stat3), and liver pro-/anti-inflammatory cytokine expressions. METHODS: Rats were divided into two groups after surgery: control group, without treatment; AG490 group, with AG490 (1 mg.kg(-1).12 h(-1)) administration intraperitoneally, immediately and through 36 hs after the operation. Western blotting was used to detect the levels of phosphorylated Jak2 and Stat3. Semi-quantitative RT-PCR was employed to examine Interleukin-6 (IL-6) and Interleukin-10 (IL-10) expression. RESULTS: At 8 h and 12 h post-operatively, the phosphorylation levels of Jak2 and Stat3 were significantly inhibited in the AG490 group when compared with the control group. The DNA levels of IL-6 in the liver of the AG490 group rat at the same time points were also decreased, whereas IL-10 levels markedly increased. These changes made the ratio of IL-6/IL-10 dropped significantly. CONCLUSIONS: AG490 ameliorates the overwhelming inflammatory response via a mechanism of blocking cytokine signaling transduction and consequently suppresses the ratio of pro-/anti-inflammatory cytokine expression, which exerts potential clinical implications of use of anti-inflammatory agents in hepatic surgery.

Animals↗

PubMed2005

[Mechanisms of increased survival rate by administration of AG490 in rats following extensive liver resection].

OBJECTIVE: To study the mechanism by which AG490 improves the survival rate of rats following extensive liver resection. METHODS: Thirty-eight rats were randomly divided into two groups after surgery: control group (n=10), without treatment; (2) AG490 group (n=28), with AG490 (1 mg x kg(-1) x 12 h(-1)) administrated intraperitoneally immediately and 36 hours after the operation. The survival rate was observed and the serum liver functions were measured. RESULTS: The survival rates of control group and AG490 group were 0% and 25%. AG490 group had significantly better blood glucose and aminotransferase levels (P < 0.05) than control group; serum bilirubin levels significantly decreased 48 hours after the operation. Serum protein levels in both two groups had slow decrease but without statistical significance (P > 0.05). CONCLUSIONS: AG490 can significantly increase the survival rate of rats following extensive liver resection. Such a benefit mainly results from the protection towards residual liver function rather than from the promotion of liver regeneration.

Alanine Transaminase↗

PubMed2004

Analysis of longitudinal marginal structural models.

In this article we construct and study estimators of the causal effect of a time-dependent treatment on survival in longitudinal studies. We employ a particular marginal structural model (MSM), proposed by Robins (2000), and follow a general methodology for constructing estimating functions in censored data models. The inverse probability of treatment weighted (IPTW) estimator of Robins et al. (2000) is used as an initial estimator and forms the basis for an improved, one-step estimator that is consistent and asymptotically linear when the treatment mechanism is consistently estimated. We extend these methods to handle informative censoring. The proposed methodology is employed to estimate the causal effect of exercise on mortality in a longitudinal study of seniors in Sonoma County. A simulation study demonstrates the bias of naive estimators in the presence of time-dependent confounders and also shows the efficiency gain of the IPTW estimator, even in the absence such confounding. The efficiency gain of the improved, one-step estimator is demonstrated through simulation.

Aged↗

PubMed2004

Effects of physical activity and body composition on functional limitation in the elderly: application of the marginal structural model.

BACKGROUND: Study of the influence of physical activity and body composition in the context of the disablement process requires analytic techniques that can address time-dependent confounding related to exposures for the occurrence of functional limitation and disability. METHODS: We applied logistic marginal structural models to explore causal relationships between leisure time physical activity and a measure of relative muscle mass (the lean:fat mass ratio) and self-reported functional limitation. Subjects (n = 1655) were members of a population-based cohort recruited in Sonoma, California, in 1993-1994 (median age 70 years); they were surveyed 3 times over 6.5 years. RESULTS: Based on the marginal structural model, the causal odds ratio for functional limitation with a 0.5-unit increment in relative muscle mass was 0.56 in women (95% CI = 0.46-0.67). This reduction in odds was not altered by adjustment for baseline covariates. The corresponding causal odds ratio in men was 0.77 (0.65-0.92). This also was not influenced by baseline covariates or levels of physical activity. There was evidence for an independent causal effect of increased levels of physical activity on reduction of odds of functional limitation for men but not for women. Obese women experienced no protective effect of increased lean-to-fat mass. Normal-weight women experienced a benefit with increasing levels of physical activity. CONCLUSIONS: Marginal structural models provide a means to address time-dependent confounding, which can occur in longitudinal studies. These analyses indicate that leisure time physical activity exerts its beneficial effects through reductions in fat mass relative to lean body mass.

Activities of Daily Living↗

PubMed2004

[Identification of the triploid hybrid chromosomes of Elymus canadensis L. x Hordeum brivisubulatum Link. by genomic in situ hybridization].

AThe intergeneric F1 hybrid between Elymus canadensis L. and Hordeum brivisubulatum Link. is a triploid (2n = 3x = 21 ), in which 7 chromosomes,that is equal to the base number of parent's chromosomes, were lost. In order to indentify the chromosome constitution of the triploid F1 hybrid of E. canadensis L. x H. brivisubulatum Link., the genomic in situ hybridization of F1 root tip cell chromosome DNA that H. brivisubulatum H1 H1 H2H2 genome DNA labeled with Biotin-16-dUTP was conducted using E. canadensis SSH(c)H(c) genome as blocking DNA. The result showed that the chromosomes of triploid F1 hybrid consisted of 7 chromosomes from E. canadensis S genome and 14 chromosomes from H. brivisubulatum H1 H2 genome while the 7 chromosomes of Hc genome of E. canadensis were lost.

Chimera↗

PubMed2004

[Effect of extract from Tripterygium hypoglaucum on proliferation and apoptosis of vascular smooth muscle cells].

OBJECTIVE: To study the effect of THW-4, an extract from Trypterygium hypoglaucum on proliferation and apoptosis of vascular smooth muscle cells (VSMC). METHODS: VSMC derived from rabbit aorta were cultured in vitro and different concentrations of THW-4 were added in experimental groups. Cell proliferation was evaluated by MTT and apoptosis by transmission electron microscopy (TEM), TUNEL assay and Annexin V-FITC/PI double labelled assay. RESULTS: The inhibitory effects of THW-4 on proliferation of VSMC displayed dose-time dependently, with the IC50 value of 15.6 microg/L at 48 hrs. Incubated with THW-4 (10-100 microg/L) for 56 hrs, VSMC mainly appeared early stage apoptosis and the percentage of apoptosis was found to raise along with the increase of the THW-4 concentration. Typical images of apoptosis could be observed under TEM and TUNEL assay showed increase of DNA segments with karyorrhexis and pyknosis after THW-4 treatment for 72 hrs. Analysis of cell cycle indicated the THW-4 mainly lead to the blockage of VSMC in G2/M stage. CONCLUSION: THW-4 could inhibit the proliferation and induce the apoptosis of VSMC in vitro, suggesting that THW-4 is a potential agent for prevention of restenosis following angioplasty.

Animals↗

PubMed2004

[Combined gene therapy enhances collateral vascularization in coronary artery occlusion swine model].

OBJECTIVE: To investigate the efficacy of combined gene transfer of vascular endothelial growth factor (VEGF) and angiotensin-1 (Ang-1) in swine coronary artery occlusion. METHODS: Swine underwent left thoracotomy followed by ligation of left anterior descending coronary artery. Constructed PCD(2)/VEGF and/or PCD(2)/Ang-1 eukaryotic expression plasmid was directly injected into the swine myocardium. RT-PCR, immunohistochemistry, capillary density and arteriole density were used to detect gene expression and biological effect. Coronary angiography was done to evaluate collateral circulation of the occluded artery. RESULTS: High levels of VEGF and Ang-1 mRNA and protein expression were detected. There was a significant increase in the number of capillaries and arterioles as compared with a control group (P < 0.05). Capillary density and arteriole density of the combination therapy group were higher than those of the swing receiving either therapy alone. Coronary angiography showed better collateral circulation in the combination therapy group. CONCLUSIONS: Direct injection of PCD(2)/VEGF and PCD(2)/Ang-1 can transfect the myocardium and express VEGF and Ang-1 protein. Combined gene transfer of VEGF and Ang-1 can increase capillary and arteriole number and enhance collateral circulation of the occluded coronary artery more effectively.

Angiotensin I↗