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Articles by T Xu
Total Records ( 2 ) for T Xu
  L Wang , B Wu , Y Sun , T Xu , X Zhang , M Zhou and W. Jiang
  Background

Previous studies have indicated that protein kinase C (PKC) may enhance endothelial nitric oxide synthase (eNOS) activation, although the detailed mechanism(s) remains unclear. In this study, we investigated the roles of PKC isoforms in regulating propofol-induced eNOS activation in human umbilical vein endothelial cells (HUVECs).

Methods

We applied western blot (WB) analysis to investigate the effects of propofol on Ser1177 phosphorylation-dependent eNOS activation in HUVECs. Nitrite (NO2) accumulation was measured using the Griess assay. The phosphatidylinositol 3-kinase/Akt (PI3K/Akt) pathway was examined by WB assay. Propofol-induced translocation of individual PKC isoforms in subcellular fractions in HUVECs was analysed using WB assay.

Results

In HUVECs, protocol treatment (1–100 µM) for 10 min induced a concentration-dependent increase in phosphorylation of eNOS at Ser1177. The NO production was also increased accordingly. PKC inhibitors, bisindolylmaleimide I (0.1–1 µM), and staurosporine (20 and 100 nM), effectively blocked propofol-induced eNOS activation and NO production. Further analyses in fractionated endothelial lysate showed that short-term propofol treatment (50 µM) led to translocation of PKC-, PKC-, PKC-, PKC-, and PKC- from cytosolic to membrane fractions, which could also be inhibited by both PKC inhibitors. These data revealed that the differential redistribution of these isozymes is indispensable for propofol-induced eNOS activation. In addition, Akt was not phosphorylated in response to propofol at Ser473 or Thr308.

Conclusions

Propofol induces the Ser1177 phosphorylation-dependent eNOS activation through the drug-stimulated translocation of PKC isoforms to distinct intracellular sites in HUVECs, which is independent of PI3K/Akt-independent pathway.

  T Du , M. R Lewin , H Wang , X Ji , H. H Bohn , T Xu , L Xu , Y Zhang and Y. Li
  Objective

To investigate the circadian and seasonal patterns in the presentation of acute upper gastrointestinal bleeding (AUGIB) in Beijing, China.

Methods

Medical records of the Beijing Emergency Medical Service System (EMSS) for 1 August 2005 to 31 July 2007 were reviewed; all patients diagnosed with AUGIB were included in the study.

Results

2580 patients were recorded in the EMSS system with a diagnosis of AUGIB during the study period. 1888 (73%) were male and 692 (27%) were female. Mean age was 53±20 years for male patients and 63±21 years for female patients. Significant differences in the presentation of AUGIB were noticed between seasons (p<0.001) and months (p<0.001). The number of cases in cold months (from December to April) was significantly higher than that in warm months (June to September). There was a significant circadian rhythm; there were fewer cases during daytime hours compared with night-time hours (p<0.001).

Conclusions

The presentation of AUGIB in Beijing has a clear seasonal and circadian rhythm. Circadian and seasonal rhythms associated with AUGIB may aid in identifying modifiable risk factors in individuals and populations.

 
 
 
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