[Pancreatic glucagon receptor radioassay with liver cell plasma membrane in normal and streptozotocin-induced diabetic rats]

Pancreatic glucagon receptor radioassay has been developed with rat liver cell plasma membrane prepared with sucrose gradient centrifugation. 125I-glucagon was prepared in this laboratory and the separation of B/F was done by low speed centrifugation with addition of PEG (W/V, 20%) and normal human serum. The specific binding of 125I-glucagon was 25%-35% and nonspecific binding was less than 5%. Reproducibility within and between- assay was 6.83% and 8.40% (CV%), respectively. Binding characteristics of glucagon receptor of normal and streptozotocin-induced diabetic rats were determined by using two methods, receptor dilution and conventional competitive binding assay. The results showed that there were no marked differences concerning high and low binding affinities between normal and diabetic rats, but the concentration of binding sites for both high and low affinity receptors was significantly higher for diabetic rats than normal rats. The possible mechanisms for the above results have been discussed.

On-line high-performance liquid chromatography for the determination of cephalosporin C and by-products in complex fermentation broths

A fully automated high-performance liquid chromatographic system was developed for optimization of cephalosporin C production. Using a simple, isocratic, reversed-phase method, cephalosporin C, deacetylcephalosporin C, deacetoxycephalosporin C, penicillin N, methionine and its decomposition product 2-hydroxy-4-methylmercaptobutyric acid were determined. The method worked reliably for 250 h and supplied information on the influence of many parameters of the process.

Protective effect of danshen during myocardial ischemia and reperfusion: an isolated rat heart study

The effect of Danshen (Radix salviae miltiorrhizae) on mechanical activity and coronary flow rate of isolated rat hearts was examined to assess the ability of Danshen to protect the myocardium against the effects of ischemia and reperfusion. After 20 min of control perfusion, in the presence or absence of Danshen, the hearts were made totally ischemic for 30 min and then reperfused for 30 min. Danshen had a negative inotropic effect and caused an increase of coronary flow rate. During post-ischemic reperfusion recovery of left ventricular developed pressure in the Danshen-treated hearts was significantly better and contracture was significantly less than in the untreated hearts. The results indicate that Danshen protects the heart against some of the deleterious effects of ischemia and reperfusion.

Comparison of particulate 3,3',5,5'-tetramethylbenzidine and 3,3'-diaminobenzidine as chromogenic substrates for immunoblot

In horseradish peroxidase (EC: 1.11.1.7)-dependent immunoblot assays, particulate 3,3',5,5'-tetramethylbenzidine (TMB) is shown to be a more efficient immunoblot substrate than the standard substrate 3,3'-diaminobenzidine (DAB), because TMB is easily prepared, stable, and less carcinogenic than is DAB. Assays of antibody in a serially diluted human immunodeficiency virus (HIV) control serum (CDC reference CAT# VS2151) have the same sensitivity limits with both DAB and TMB (1:312,500). Complete, working substrate solutions of H2O2/TMB/enhancer and of H2O2/DAB were stored at room temperatures and at 48 degrees C respectively. Periodic tests showed the TMB substrate system to be functional after four weeks at 48 degrees C and after eight weeks at room temperature, while the DAB system was functional after one week at 48 degrees C and after four weeks at room temperature. The stability, safety, and convenience of the commercially available TMB kits make this substrate ideal for immunoblot tests.

[Measurement of the anterior chamber depth with the slitlamp and the keratometer]

A simple and accurate formula for the measurement of the anterior chamber depth with keratometer and slitlamp is described. The calculation takes into consideration the curvature of the anterior corneal surface and the refractive index of the aqueous. The method was tested with a model of anterior chamber double-blindly and proved accurate and reliable. The average anterior chamber depth of 50 patients (100 eyes) measured by this method was 2.97 +/- 0.22 mm.

Effect of A-nor steroids and oestradiol on progesterone production by human luteal cells

Cell suspensions were prepared from human corpora lutea obtained during the mid-luteal phase. Progesterone production was assessed after short-term incubation of luteal cell suspensions. Luteal cells were very sensitive to hCG, the concentration required for 50% maximum response being 0.01 i.u./ml, and the response was 5 times higher than the basal production. Oestradiol (1-100 microM) induced a significant dose-related decrease in both basal and hCG-stimulated progesterone production. The A-nor steroidal compounds anordrin and AF-45 reduced hCG-stimulated progesterone production only at the high concentration of 100 microM. The ED50 values were approximately 3 microM, 75 microM and 100 microM for oestradiol, AF-45 and anordrin respectively. Anordrin showed no significant effects on basal progesterone production. In addition, oestradiol markedly inhibited the activity of 3 beta-hydroxysteroid dehydrogenase in luteal cells, expressed by the conversion of pregnenolone to progesterone, but the inhibitory effects of anordrin and AF-45 were negligible or relatively low. The effects of anordrin and AF-45 were different from those of oestradiol on progesterone production by human luteal cells in vitro, indicating that neither substance is likely to be a useful luteolytic agent in women.