Polygraphic recording in the rat by a miniaturized radiotelemetric technic]

The authors describe the results obtained on rats by a method of four channel telemetric recording system. The transmitter with a range of a few meters, has a pass band from 0,3 to 400 Hz, weighs 4 grams and can operate autonomously for a minimum of 10 days.     

Thermal melting and circular dichroism of DNA complexes with (Lys-Ala-Ala)10 and (Lys-Ala-Ala)n: effect of polypeptide chain length

DNA complexes with polypeptides (Lys-Ala-Ala)₁)] and (Lys-Ala-Ala)₃₄ have been studied using the methods of thermal melting and circular dichroism. Derivative melting curves of (Lys-Ala-Ala)₁₀ DNA differed substantially from those of (Lys-Ala-Ala)₃₄ prepared either by salt gradient dialysis or by direct mixing. Melting curves of the former complex were unimodal or bimodal with T_m increasing continuously withn input lysin-to-DNA phosphate ratio (r); those of the latter complex consisted of three separate transitions with T_m values almost independent of r. Complete reversibility of binding in the (Lys-Ala-Ala)₁₀-DNA system but a slow redistribution of (Lys-Ala-Ala)₃₄ on DNA at low temperature were found in the redistribution experiments Much faster redistribution from denatured to native DNA occurs at the temperature of melting, contributing to the unusual trimodal melting pattern. Circular dichroism curves are very similar for both complexes and indicate little change of DNA conformation upon polypeptide binding.     

In vitro effect of 5 alpha-androstane-3 beta, 17 beta diol on the liberation of follicle stimulating hormone (FSH) induced by LH-RH

A continuous flow incubation (perifusion) was used to examine the effect of 5 alpha-androstane-3 beta, 17 beta diol 3 beta diol) on the release of FSH induced by LH-RH. Over a 3 h-period the 3 beta diol exerts inhibitory effects on male and female pituitaries at high dose (1 microgram/ml) and only on male pituitaries at low dose (100 ng/ml).     

Adrenergic reactions of sheep rumen in vitro

The alpha and beta-adrenergic responses of the isolated muscle of sheep rumen were analysed by pharmacodynamic methods after administration of alpha and beta-adrenergic agonists and alpha and beta-adrenergic antagonists. It was found that phenylephrine, and in a lower degree propranolol, stimulated contractions of isolated muscle of sheep rumen while adrenaline, noradrenaline, isoprenaline, phenoxybenzamine and regitine inhibited these contractions. Propranolol abolished the dilating (atonic) effect of catecholamines on the isolated muscles of sheep rumen and previous blockade of beta-adrenergic receptors with propranolol reversed the dilating effects of catecholamines. It is concluded that noradrenaline has an ambiceptor effect (similar to that of adrenaline) on the isolated muscle of the rumen.     

Histochemical study of the myelin-associated carbohydrates.

Myelin-associated carbohydrates were studied by means of histochemical techniques in the central nervous system of birds and mammals. Polianions in the surface of myelin and in interfascicular oligodendroglia were detected using histochemical techniques. Glycoproteins were studied by means of concanavalin A. The Con-A-PO-DAB sequence was used. Concanavalin-A-binding sites were detected in oligodendroglia and on the myelin surface. Similar results were observed in both birds and mammals. The processes of the interfascicular oligodendroglia also contain carbohydrates. A close association between the carbohydrates of these glial processes and the myelin surface carbohydrates was demonstrated, and their probable identity is assumed.