Biomedical subjects

Sun Li

Publications and source records attributed to Sun Li.

4 recordsLinked to original sources

PubMed2006

KCNE2, a down-regulated gene identified by in silico analysis, suppressed proliferation of gastric cancer cells.

It is important to identify the differentially expressed gene in gastric cancer for elucidating the molecular mechanisms of tumorigenesis of stomach. Here, 38 genes differentially expressed genes between gastric cancer and normal gastric mucosa by in silico approaches. A potassium channel protein KCNE2, identified as a down-regulated gene in gastric cancer, was chosen for further study. We investigated the expression of KCNE2 in gastric cancer tissues and cell lines and examined the effect of KCNE2 on proliferation of gastric cancer. The expression of KCNE2 was markedly down-regulated in gastric cancer tissues and cell lines. Forced overexpression of KCNE2 suppressed the growth of SGC7901 cells and cell cycle progression significantly, which might be related to the down-regulation of Cyclin D1. KCNE2 also inhibited SGC7901 cell growth in soft agar and its tumorigenicity in nude mice. Taken together, our work showed that in silico analysis approaches could be used to identify cancer-related genes effectively. KCNE2, as a novel down-regulated gene in gastric cancer, suppressed cell proliferation and tumorigenesis of stomach.

Animals↗

PubMed2005

Decrease of CD4+ T-lymphocytes in children exposed to environmental lead.

The effects of environmental lead on the immune system of young children were assessed by determining the peripheral blood lymphocytes CD3+, CD4+, CD8+, B(CD19+) counts, and natural killer (CD16+CD56+) cells in 35 preschool children whose mean blood lead level was 140.6 microg/L. The results were compared to an age- and sex-matched control group with a mean blood lead level of 64.3 microg/L. Compared to the controls, a significant reduction in the percentage of CD4+ cells and a significant increase of CD8+ cells were seen in the high-lead group. The negative correlation between the percentage of CD4+ cells and blood lead levels was found to be significant (p<0.01). These results suggest that exposure to environmental lead might result in alterations in the immune function of young children.

Antigens, CD19↗

PubMed2004

Preschool children's lead levels in rural communities of Zhejiang province, China.

The aim of the study was to determine mean blood lead levels (BLLs) and prevalence of elevated BLLs among preschool children aged 3-6 years in Zhejian rural communities, China. Data were gathered by means of a questionnaire and blood lead analyses for 217 children who attended six randomly selected kindergartens. BLLs ranged from 25-437 microg/l. Arithmetic mean was 95 microg/l and standard deviation was 56 microg/l. BLLs of 63 samples (29.0%) were > or =100 microg/l. Children with BLLs > or =100 microg/l came from families with a higher proportion of their fathers or mothers working in conditions of potential exposure to lead, as compared to those with BLLs <100 microg/l (P < 0.01). A significantly higher proportion of children with BLLs > or =100 micro/l lived in buildings that were located near small industries, such as mechanics, furniture, or paint shop, as compared to those with BLLs <100 microg/l (P < 0.01). In conclusion, the data indicate that high levels of childhood lead exposures even prevail in rural communities and deserve authorities' attention. With the recent ban of leaded gasoline in China, emphasis should shift to other sources of exposure in children.

Child↗

PubMed2002

Ca(2+) influx through the osteoclastic plasma membrane ryanodine receptor.

We predict that the type 2 ryanodine receptor isoform (RyR-2) located in the osteoclastic membrane functions as a Ca(2+) influx channel and as a divalent cation (Ca(2+)) sensor. Cytosolic Ca(2+) measurements revealed Ca(2+) influx in osteoclasts at depolarized membrane potentials. The cytosolic Ca(2+) change was, as expected, not seen in Ca(2+)-free medium and was blocked by the RyR modulator ryanodine. In contrast, at basal membrane potentials (approximately 25 mV) ryanodine triggered extracellular Ca(2+) influx that was blocked by Ni(2+). In parallel, single-channel recordings obtained from inside-out excised patches revealed a divalent cation-selective approximately 60-pS conductance in symmetric solutions of Ba-aspartate [Ba-Asp; reversal potential (E(rev)) approximately 0 mV]. In the presence of a Ba(2+) gradient, i.e., with Ba-Asp in the pipette and Na-Asp in the bath, channel conductance increased to approximately 120 pS and E(rev) shifted to 21 mV. The conductance was tentatively classified as a RyR-gated Ca(2+) channel as it displayed characteristic metastable states and was sensitive to ruthenium red and a specific anti-RyR antibody, Ab(34). To demonstrate that extracellular Ca(2+) sensing occurred at the osteoclastic surface rather than intracellularly, we performed protease protection assays using pronase. Preincubation with pronase resulted in markedly attenuated cytosolic Ca(2+) signals triggered by either Ni(2+) (5 mM) or Cd(2+) (50 microM). Finally, intracellular application of antiserum Ab(34) potently inhibited divalent cation sensing. Together, these results strongly suggest the existence of 1) a membrane-resident Ca(2+) influx channel sensitive to RyR modulators; 2) an extracellular, as opposed to intracellular, divalent cation activation site; and 3) a cytosolic CaM-binding regulatory site for RyR. It is likely therefore that the surface RyR-2 not only gates Ca(2+) influx but also functions as a sensor for extracellular divalent cations.

Animals↗