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Biomedical subjects

S Q Chen

Publications and source records attributed to S Q Chen.

At least 19 recordsLinked to original sources
PubMed2001

Phenotype analysis of cytochrome P450 2C19 in Chinese subjects with mephenytoin S/R enantiomeric ratio in urine measured by chiral GC.

A chiral gas chromatographic method with FID was developed for the determination of S- and R-mephenytoin in human urine. The assay is linear from 25 to 800 ng/mL for each enantiomer and the limit of detection and limit of quantitation were 12 and 25ng/mL for each enantiomer, respectively. The method affords average recoveries of 74.41 +/- 3.93% and 73.78 +/- 3.02% for S- and R-mephenytoin, respectively. The method allows the phenotype study of CYP2C19 in Chinese subjects. The phenotype pattern of 90 Chinese volunteers was determined, in which 26 volunteers received phenotyping and genotyping tests. The results of phenotype analysis showed that the interindividual variation was marked. The mephenytoin S/R enantiomeric ratios in urine of 11 volunteers were > or = 0.95 and identified as poor metabolizers. The frequency of poor metabolizers was 12.2% in the Chinese subjects tested. A good relationship between phenotype and genotype analysis of CYP2C19 was observed.

Aryl Hydrocarbon Hydroxylases↗
PubMed1999

Correlation between cytochrome P-450 CYP2D6 (CYP2D6) genotype and phenotype.

AIM: To study the correlation between CYP2D6 genotype and its phenotype. METHODS: CYP2D6 genotyping was made by detecting CYP2D6*3, *4, *6, and *7 alleles with an allele-specific polymerase chain reaction procedure. RESULTS: The CYP2D6 genotypes were well correlated with its phenotypes in all 125 extensive metabolizers and in 43 poor metabolizers. Extensive metabolizers had at least one wildtype CYP2D6 gene and the genotypes were *1/*1, *1/*3, and *1/*4. Poor metabolizers were found to be homozygous mutants of CYP2D6 gene and the genotypes were *3/*4, *4/*4, *3/*6, *4/*7, *4/*6, and *6/*6. CONCLUSION: Genotype could be used to screen variations of CYP2D6 expression.

Adult↗
PubMed1997

Physiological basis for long life span.

A collection of clinical data is reported on nonagenarians in comparison to an 'average' population of younger age. The results of these clinical data indicated that a vital physiological basis for long life span probably existed. The basis include a better micro-blood-flow state, a better cardiac, immune (nature killer cell activity), adrenocortical, hepatic and renal function, and a higher level of high density lipoprotein cholesterol. It is suggested that the method, including Chinese traditional medicine, to improve the micro-blood-flow, nature killer cell activity, high density lipoprotein cholesterol and vital organ function may be beneficial for life preservation and aging retarding.

Aged↗
PubMed1997

[Distinguishing CYP2D6 homozygous and heterozygous extensive metabolizers by dextromethorphan phenotyping].

A more sensitive procedure was developed to phenotype cytochrome P450 2D6 metabolism by a less toxic probe drug--dextromethorphan. The sensitivity of the determination of dextromethorphan in urine samples was up to 1 ng.ml-1. This method was employed to phenotype three groups of subjects. The results showed that there was a difference between extensive metabolizers which were genotyped as homozygotes and heterozygotes. Although the difference was not as big as the difference with poor metabolizers which were genotyped as homozygous mutants. It suggests that "gene copy" is a true factor in the expression of CYP2D6 genes.

Chromatography, High Pressure Liquid↗
PubMed1995

[Role of afferent renal nerves in 2K2C Goldblatt hypertension].

In order to study the role of afferent renal nerves in 2K2C Goldblatt hypertension, the renal afferent nerves were selectively lesioned by bilateral T9-L2 spinal dorsal rhizotomy before clipping (internal diameter, 0.3 mm) of birenal arteries. Systolic blood pressure of the rat was measured by tail-cuff method. Concentrations of catecholamines, Ang II, and aldosterone were determined respectively by HPLC-EC and RIA, and vascular structural changes were measured by blood vessel micro-image analysis system coupled with a computer. The results showed that the concentrations of NE and E in medulla oblongata, adrenal gland and plasma, and of plasma Ang II and aldosterone as well as body weight of the rat were all significantly increased. The heart coefficient (heart wt/body wt), the media thickness, and the media thickness/lumen diameter in superior mesenteric arteries were also increased in 2K2C hypertensive rats (clipping, 6 wk) as compared with those in control rats. Bilateral rhizotomy delayed development of 2K2C hypertension and prevented above-mentioned vascular structural changes, the NE and E concentrations of medulla oblongata, adrenal gland and plasma were all decreased, hypothalamic NE and E were increased, and plasma Ang II level was not significantly changed. These results suggest that afferent renal nerves may play a partial role in the development of hypertension in 2K2C rats by activating sympathetic nervous system as a result of affecting metabolic activities of brain catecholaminergic neurons, and that high-plasma Ang II and aldosterone as well as heart hypertrophy and proliferation of vascular smooth muscle cells may also participate in the pathogenesis of hypertension in 2K2C rats.

Afferent Pathways↗
PubMed1995

[Epidemiological study of hepatitis C virus (HCV) infection in plasmapheresis and blood donors].

We actively adopted method to control hepatitis C (HC) epidemic in blood sampling. ELISA was used to detect anti-HCV antibody in different groups of 2348 blood donors. The positive rates of anti-HCV for plasmaphersis and whole blood donors were 0.58% (2/343) and 1.34% (27/2005) respectively, with no statistical significance (P > 0.05). The positive rates of anti-HCV for plasmapheresis donors in 1-2 years and over 9 years were 0.99% (7/701) and 0.74% (2/270) respectively. There was no significant difference (P > 0.05) either. The positive rates of anti-HCV for plasmapheresis donors in 1992 and in 1994 were 1.64% (7/426), and 0.58% (2/343). The results showed that HCV infection rate did not increase in plasmapheresis donors, nor did it increase parallel with the increasing gears of blood donnation.

Blood Donors↗
PubMed1995

[Mutagenic effects of bimolane].

AIM: To study the genotoxicity of bimolane. METHODS: Bimolane 5, 10, and 15 mg . kg-1 was injected i.p. in mice to investigate its effects on chromosome/chromatid aberrations of bone marrow cells. Mutagenic effects on TA97, TA98, TA100, TA102 were studied in Ames test. RESULTS: Bimolane 5, 10, and 15 mg . kg-1 induced of chromosome/chromatid aberrations, and the frequency of aberration cells (ACF) induced by bimolane increased markedly (P < 0.01); Bimolane without S9 showed mutagenic to TA98 and TA102 at the concentrations of 100 and 150 micrograms/plate in Ames test. CONCLUSION: Bimolane is a kind of genotoxic compound.

Animals↗
PubMed1994

Suppressing effects of human fetal cell extract on micronuclei induced by cyclophosphamide in mice.

The genotoxicity of human fetal cell extract (HFCE) and its effect on the frequency of micronucleated polychromatic erythrocytes (PCE-MNF) in mice induced by cyclophosphamide (CP) were studied. Statistically significant differences were not found between the control group and each group treated with HFCE (0.3, 3, 30 mg/kg bw). CP (200 mg/kg bw) induced a marked increase in MNF (P < 0.01). Administered together with CP, HFCE suppressed the increase of MNF induced by CP. The reduction effect is dependent on the dose of HFCE. At doses of 3 and 30 mg/kg bw HFCE, MNF decreased markedly (P < 0.05 and < 0.01, respectively). It showed that HFCE did not induce micronucleus formation, while it could suppress the micronucleus formation induced by CP in mice. The results suggested that HFCE might be antimutagenic and have potential value in clinical application.

Animals↗
PubMed1994

[Amplification of C-erB-2 oncogene in colon carcinomas].

Differential PCR has been used to detect the variance of c-erbB-2 gene copies in 23 colon carcinoma tissues. It was found that amplification of c-erbB-2 gene existed in 7 out of 23 (30%) cases. All of the three high-middle differentiated colon carcinomas had amplification of c-erbB-2 gene in our specimens. It was higher than that of the middle differentiated colon carcinomas (P < 0.05). The rate of amplification of c-erbB-2 gene in patients with positive lymph node was approximately two times as high as that in negative nodo patients, but this difference was not significant (P > 0.20).

Adenocarcinoma↗
PubMed1992

[A study on the regulation of ACTH secretion in rat pituitary cells].

In addition to method of ACTH RIA, a rat pituitary cell perfusion system was developed for the assessment of pituitary cells in stimulating and inhibiting ACTH secretion induced by some substances. Hypothalamic extract stimulated the ACTH secretion in a dose-dependent manner. AVP, cAMP, Ca2+, K+, noradrenaline, metoclopramide and haloperidol also had some stimulating effect. Dexamethasone and dopamine inhibited the basal ACTH secretion of pituitary cell and antagonized the effect of the various stimulating substances. Cyproheptadine could antagonize the effect of some of the stimulating substances while GABA had no marked inhibiting effect.

Adrenocorticotropic Hormone↗
PubMed1989

Biochemical and morphological studies of steady state and lipopolysaccaride treated bovine articular cartilage explant cultures.

Explants of bovine articular cartilage were cultured for up to 50 days in 20% fetal calf serum in the presence or absence of the endotoxin lipopolysaccharide (LPS); or in various protocols involving different treatment times with LPS followed by recovery times in the absence of LPS. Cultures were measured in terms of rates of proteoglycan synthesis (incorporation of [35S]sulfate), proteoglycan contents and collagen contents. Histological sections were prepared for both light and electron microscopy. In fetal calf serum, the rates of synthesis and contents of proteoglycans per collagen remained constant, while for LPS treated cultures both parameters decreased. For recovery groups, the rates of proteoglycan synthesis increased during the time of recovery if the LPS treatment times were relatively short (2 weeks or less) and if the tissue was obtained from younger animals; net increase in proteoglycan contents occurred infrequently if at all during recovery protocols. Histological examinations revealed that chondrocytes in cultures maintained in fetal calf serum appeared normal with large stores of glycogen. In LPS treated cultures, chondrocytes were depleted of glycogen stores and contained numerous lipid droplets. In recovery cultures, chondrocytes replenished their glycogen contents, but the lipid droplets remained. For both LPS treated and recovery groups the extracellular matrix was depleted of proteoglycans with time in culture. The results provide further evidence for the ability of this explant culture system to maintain steady state metabolic parameters for proteoglycan metabolism over long time periods and for its utility to study reagents which regulate or perturb these parameters.

Aging↗