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Biomedical subjects

Xu Chen

Publications and source records attributed to Xu Chen.

43 records · Page 3Linked to original sources
PubMed2003

[Fluoride concentration in saliva after use of fluoride varnish].

OBJECTIVE: The purpose of this vivo study was to compare fluoride concentration in saliva of patients treated with fluoride varnish and fluoride solution. METHODS: 20 5-year-old children were selected and divided into fluoride varnish and fluoride solution groups. The samples of unstimulated whole saliva were collected at base-line before and after 0.25h,0.5h,1h,2h,6h,12h,24h treatment with fluoride varnish and fluoride solution. Saliva fluoride concentrations were measured using an ion-specific electrode. RESULTS: After 0.25h,0.5h,1h,2h,6h treatment with fluoride varnish, the values of salivary fluoride concentration were higher than baseline,the values of fluoride varnish group were higher than those in fluoride solution group after 0.5h to 6h. CONCLUSION: Compared with fluoride solution, fluoride varnish maintained a longer time of high salivary fluoride concentration.

Child, Preschool↗
PubMed2003

[An analysis of the state of teeth of 961 elderly cadres in Shenyang City].

OBJECTIVE: To assess the current state of teeth in elderly cadres in Shenyang City. METHODS: According to the standards of the 2nd national oral health sampling survey, 961 elderly cadres, above 60 years old, were examined. The results were processed using SPSS. RESULTS: 67.12% had dental caries and among them 33.18% were completely treated. The mean numbers of decayed and filled teeth in persons with caries become higher with the increase of ages (P<0.05). 80.65% of individuals had lost partial or all of their teeth. The mean number of lost teeth was 7.38. The number of teeth present had a negative correlation to ages (P<0.01). The state of periodontal health also had a negative correlation to ages(P<0.01). 10.20% was the edentate and 98.98% of them were wearing complete dentures. Among the elderly with part of their teeth lost, 36.04% had prosthetic restoration. CONCLUSION: Teeth loss is common in elderly population. Dental caries and periodontal diseases are two main causes. To increase the treatment rates of dental disease, it is evident to improve the oral health awareness in elder persons.

Age Factors↗
PubMed2002

Cholesterol depletion from the plasma membrane triggers ligand-independent activation of the epidermal growth factor receptor.

We recently demonstrated that depletion of plasma membrane cholesterol with methyl-beta-cyclodextrin (MbetaCD) caused activation of MAPK (Chen, X., and Resh, M. D. (2001) J. Biol. Chem. 276, 34617-34623). MAPK activation was phosphatidylinositol 3-kinase (PI3K)-dependent and involved increased tyrosine phosphorylation of the p85 subunit of PI3K. We next determined whether MbetaCD treatment induced tyrosine phosphorylation of other cellular proteins. Here we report that cholesterol depletion of serum-starved COS-1 cells with MbetaCD or filipin caused an increase in Tyr(P) levels of a 180-kDa protein that was identified as the epidermal growth factor receptor (EGFR). Cross-linking experiments showed that MbetaCD induced dimerization of EGFR, indicative of receptor activation. Reagents that block release of membrane-bound EGFR ligands did not affect MbetaCD-induced tyrosine phosphorylation of EGFR, indicating that MbetaCD activation of EGFR is ligand-independent. Moreover, MbetaCD treatment resulted in increased tyrosine phosphorylation of EGFR downstream targets and Ras activation. Incubation of cells with the specific EGFR inhibitor AG4178 blocked MbetaCD-induced phosphorylation of EGFR, SHC, phospholipase C-gamma, and Gab-1 as well as MAPK activation. We conclude that cholesterol depletion from the plasma membrane by MbetaCD causes ligand-independent activation of EGFR, resulting in MAPK activation by PI3K and Ras-dependent mechanisms. Moreover, these studies reveal a novel mode of action of MbetaCD, in addition to its ability to disrupt membrane rafts.

3T3 Cells↗
PubMed2002

Some new aspects in biosensors.

This paper reviews recent advances in biosensors contributed mainly by our laboratory. The biosensors, based on the new immobilization materials - sol-gel organic-inorganic hybrid materials, cryohydrogel (or organohydrogel) and bilayer lipid membranes, are presented. The analytical performances of the biosensors are discussed. Applications of the biosensors in extreme environment are emphasized. A new generation of biosensors - surface plasmon resonance biosensors and capacitance biosensors, are also described.

Biosensing Techniques↗
PubMed2002

[Protective effects of Zn-metallothionein on erythrocyte membrane of rats with severe scalding after delayed resuscitation].

OBJECTIVE: To study the antagonism of Zn-metallothionein (Zn-MT) to oxidative stress of rats with severe scalding after delayed resuscitation. METHODS: 27 Wistar rats were randomly divided into three groups: normal control; burn with delayed fluid resuscitation group; and Zn-MT protected group. The rats were scalded with 30% total body surface area (TBSA) third degree burn. Four hours after injury, they were resuscitated, but Zn-MT (1 x 10(-5) mol/L) was given in the third group rats. 24 hours after they were scalded, blood was taken, RBCs were separated and labeled with electron spin resonance (ESR) spin label 3-maleimido-proxy l to detect membrane protein conformation. The serum was collected and added into the reaction system of xanthine, xanthine oxidase and ESR spin trap 5, 5-dimethylpyroline-N-oxide to assay the levels of superoxide dismutase (SOD) by ESR. RESULTS: The ratios of strong solidity and weak solidity of RBC membrane proteins in the three groups were 0.352 +/- 0.043, 0.409 +/- 0.027, and 0.386 +/- 0.062 respectively, and the revolved times of membrane proteins were 1.300 +/- 0.210, 1.576 +/- 0.190 and 1.381 +/- 0.210 seconds respectively. Compared to the first group, the membrane protein conformation in the second group was changed remarkably, and the speed of membrane protein movement decreased significantly. However, those changes were alleviated obviously by Zn-MT. The SOD levels in serum of the three groups rats were 73.2% +/- 1.4%, 48.8% +/- 3.8% and 66.8% +/- 3.2% respectively. Compared to the normal control group, the SOD levels in serum of the second group decreased obviously. However, an excess of oxygen free radicals produced after injury could be scavenged by Zn-MT. CONCLUSION: RBC membrane proteins of rats with severe scalding after delayed resuscitation were injured by oxygen free radicals produced after injury, and Zn-MT could alleviate this injury.

Animals↗