[Study on 125I-labeled human chorinic gonadotropin after purification through gel electrophoresis]

Radioiodination of HCG with 125I Na using chloramine-T is widely employed. However, 125I-HCG damages in storage and thus results in decrease of immunological and biological activities. When 125I-HCG was in store as long as 30 days, the immunological activity and biological activity decreased from 100% to 33.1% and 44.0%, respectively. We used polyacrylamide gel electrophoresis to purify 125I-HCG which had been kept in store for 30 days since radiolabeling, and we found the binding capacities of purified 125I-HCG increased. The combination rates of purified 125I-HCG with antibody and receptors accounted for 90.5% and 95.3% of those of 125I-HCG 1 day after radiolabeling. These results suggest that 125I-HCG which has been stored for a period since radiolabeling should be purified before use.

[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.

[Therapeutic effects of Chinese drugs on early renal damage of rats caused by fish bile]

The therapeutic effects of Salvia miltiorrhizae, Typha angustifolia, Rheum palmatum preparations on early renal damage of rats caused by fish bile were observed. These drugs were effective in reducing serum creatinine, urinary NAGase, count of necrosed epithelial cells of proximal tubule and that of glomerular filled with RBC in Bowman's space (P < 0.05), and also effective in increasing creatinine clearance (P < 0.05).

[Studies on preparation technology of microspheres of contraceptives]

Contraceptive poly ethylglycol-lactide (PEGL), an artificial biodegradable polymer microsphere was prepared by a solvent evaporation process using levonorgestrel (LNG) and estradiol (E2) as model drugs and PEGL as the core material. The experimental conditions were optimized, the mean volume diameter obtained being 30 microns and rate of encapsulation 75-82%. In vitro, it was found that the drug release rate decreased with decreasing drug content in the microspheres. The microspheres of the contraceptive maintained anticonception duration in mice for over 6 months, indicating that the microspheres have remarkably long acting sustained release action.

Exon skipping gives rise to alternatively spliced forms of the estrogen receptor in breast tumor cells

We have previously described three messenger RNA variants coding for the human estrogen receptor (ER) [1]. These variants were identified using the polymerase chain reaction to perform directed cloning of ER cDNAs synthesized from polyadenylated RNA extracted from the human breast cancer cell line T47D. Each of the variants is characterized by the precise deletion of a single exon within the protein coding region of this message and was presumably derived by inaccurate or promiscuous splicing of primary estrogen receptor transcripts. We report here the results of RNAse protection experiments which independently confirm the existence of these splicing variants in T47D cells. Similar analysis of RNA from MCF-7 cells also revealed the presence of variant ER transcripts, suggesting that they may be a common finding in tumor cell lines which express the estrogen receptor. However, attempts to identify splicing variants in a number of nominally ER-negative cell lines using either RNAse protection or PCR amplification were without success.

[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.

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.

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.

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.

[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.