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Y Lei

Publications and source records attributed to Y Lei.

62 records · Page 4Linked to original sources
PubMed1993

[Studies on a radioligand-receptor binding assay of human chorionic gonadotropin in rat testis].

A radioligand-receptor binding assay for human chorionic gonadotropin (HCG) has been established with cell membranes preparation of rat testis. Partially purified cell membranes preparation was prepared from rat testis by sucrose density gradient ultracentrifuge. The binding assay was performed by incubating 125I-HCG with rat testis cell membranes preparation at 30 degrees C for 1.5 h in a total incubation volume of 0.5 ml. Scatchard plot analysis for the binding assay revealed a linear binding plot and yielded a bound capacity of testis cell membranes receptors of 0.36 x 10(-12) mol/micrograms protein. KD of 0.45 x 10(-10) mol/L. Hill coefficient was 0.976. Studies on the kinetics of the reaction of radioligand-receptor binding showed that the mean values for the association rate (k1) and dissociation constants (k2) were individually 0.41 x 10(-3) pmol/min and 2.12 x 10(-3) pmol/min; the dissociation plot was two-phase, with 15 x 10(-3) pmol/min of fast-phase and 1.5 x 10(-3) pmol/min of slow-phase.

Animals↗
PubMed1992

[Clinical epidemiological study on risk factors of coronary heart disease in 743 subjects].

This paper sums up the clinical epidemiological investigation data on risk factors (RF) of coronary heart disease (CHD) among 743 office workers, with an average age of 61.0 +/- 8.0. The investigation involved factors relating to history, physical examination, biochemistry, blood rheology and TCM Syndrome Differentiation. According to the results of the computerized single-factor correlation analysis, the incidence of CHD in RF exposed group was obviously higher than that of unexposed one, 65 RF such as hypertension, diabetes, hyperlipemia, smoking, body weight, HDL-C/TC, blood viscosity etc. were recorded. Using multivariate regressive analysis it revealed that hypertension, diabetes, total cholesterol, heavy cigarette smoking, overweight, diastolic pressure, cortisol, TCM senile index, Blood Stasis Syndrome, Qi Stagnation Syndrome, Qi Deficiency Syndrome and Heart Deficiency Syndrome were the main RF. The result concerning RF of Western medicine (WM) was in conformity with that at home and abroad. In addition, some TCM-RF were selected which couldn't be replaced by WM-RF. These indicate that there are TCM-RF and WM-RF in the development of CHD and it is better to adopt the method for preventing and treating CHD with combined TCM-WM. As to TCM-RF of CHD, the authors consider that there are both the factors of Deficiency and Excess, so preventing and treating CHD should aim at reinforcing the Deficiency and reducing the Excess.

Adult↗
PubMed1991

Ofloxacin-resistant Pseudomonas aeruginosa mutants with elevated drug extrusion across the inner membrane.

We selected the quinolone-resistant mutants from the protein F deficient Pseudomonas aeruginosa. The mutants showed cross-resistance to tetracycline, minocycline and chloramphenicol, but not to the beta-lactam antibiotics. The MIC of ofloxacin (OFLX) against the mutants, but not in the parent, became 2 to 4 times lower as the medium pH was raised from 6.5 to 8.5. The mutants accumulated about half as much OFLX as the parent. The OFLX accumulation in the mutants increased 6.5- to 8-fold in the presence of 100 mM carbonyl cyanide m-chlorophenylhydrazone, while that in the parent was 4-fold. The OFLX sensitivity of the mutant DNA-gyrase was comparable with that of the parent's enzyme. These results suggest that the resistance of these mutants to OFLX is associated with the membrane potential dependent drug efflux.

Anti-Bacterial Agents↗
PubMed1991

Factors that influence the permeability assay of the outer membrane of Pseudomonas aeruginosa.

Brief exposure of Pseudomonas aeruginosa to a temperature of 10 degrees C or lower caused a significant leakage of the periplasmic beta-lactamase into the medium. The extent of leakage increased as the incubation temperature was lowered to 4 degrees C and reached a maximum at 0 degrees C. Cells grown in the presence of beta-lactamase inducers were unsuitable for the permeability assay. It was found that the diffusion rates of beta-lactams through the outer membrane of P. aeruginosa were much lower than those previously reported, as assayed under refined conditions. The diffusion rates of beta-lactams in one of the mutants tested were an order of magnitude lower than those of the other strains, despite the fact that the outer membrane protein profile of the strain appeared to be indistinguishable from those of the others. These results suggest that beta-lactam antibiotics diffuse through the outer membrane of P. aeruginosa, at least partly, through a non-porin pathway.

Cell Membrane Permeability↗
PubMed1990

Radiolabeling of Necator americanus third stage larvae with 75Se-methionine.

Third stage larvae of Necator americanus were radiolabeled with 75Se-methionine by two methods. Larvae labeled in aqueous cultures contained 188 and 25 cpm per sheathed and ex-sheathed larva, respectively. Larvae labeled in coproculture incorporated 25 and 18 cpm per sheathed and ex-sheathed larva, respectively. All of the label was decayed in 5 days from larvae labeled in aqueous cultures, whereas appreciable amounts of radioactivity were still detectable at day 7 of chase period in coproculture labeled larvae.

Animals↗
PubMed1989

[Affinity of penicillin-binding proteins of Escherichia coli K-12 for furbenicillin and other beta-lactam antibiotics].

Penicillin-binding proteins (PBP) are vitally important targets in relation to the killing of bacteria by beta-lactams. The affinities of PBP of Escherichia coli K 12 for ampicillin, mecillinam and for ureidopenicillins were studied by sodium dodecylsulphate polyacrylamide slab gel electrophoresis and fluorography. The results showed that furbenicillin, a semisynthetic ureidopenicillin developed in China, bound to all 3 essential target proteins of E coli. The IC50 values of furbenicillin to PBP 1 b, PBP 2 and PBP 3 were 4.55 mg/L, 0.37 mg/L and 0.06 mg/L, respectively. The affinities of the 3 proteins of E coli for furbenicillin were 2.5-, 3.5-, and 2.5-fold, respectively higher than that of azlocillin. Mecillinam bound exclusively to PBP 2 (IC50: 0.16 mg/L). Mezlocillin and piperacillin showed higher affinities for PBP 3 than furbenicillin, but their affinities for PBP 1 b and PBP 2 were much lower than furbenicillin.

Anti-Bacterial Agents↗