Catecholaminergic component of the action of a heptapeptide analog of ACTH4-10 on the open-field behavior of rats

Heptapeptide Met-Glu-His-Phe-Pro-Gly-Pro (ACTH4-10 analog) at a dose of 0.015 mg/kg failed to alter open field behaviour of rats in the first test series. The peptide abolished amphetamine-induced stimulation of the exploratory and grooming behaviour. Extinction of the rats' exploratory behaviour during second test series in the open field (7 days later) was disturbed when haloperidol or apomorphine were injected before the first test series. When the peptide was administered with haloperidol or apomorphine, the extinction tended to become normal. Heptapeptide failed to change noradrenaline, dopamine or 5-hydroxytryptamine content in the rat forebrain. However, this peptide at a concentration of 10(-4) M moderately diminished tyrosine hydroxylation velocity in the rat striatal or hypothalamic synaptosomes, the effect depending on tyrosine concentration. These data suggest the involvement of catecholaminergic component into the heptapeptide action on the behaviour of rats.     

Monodeiodination of thyroxine to 3, 5, 3'-triiodothyronine and to 3, 3', 5'-triiodothyronine in isolated dog renal cortical tubuli

Monodeiodination of T4 to T3 and rT3 in the intact cells of dog renal tubuli and glomeruli was investigated. The tubuli and glomeruli were obtained by a sieve method. T4 (2 micrograms/ml) was incubated in Tris-HCl buffer, pH 7.5, with renal cells (180 micrograms protein/ml) and 5 mM DTT for 1 h at 37 degrees C and the T3 and rT3 generated during incubation were measured by specific radioimmunoassays. In order of decreasing activity, dog renal cortical tubuli, cortical homogenate, glomeruli and medullary tubuli were capable of converting T4 to T3. Net rT3 production from T4 in cortical tubuli was also greater than that in cortical homogenate. The conversion of T4 to T3 and also to rT3 in cortical tubuli was enzymatic in nature, since the reactions showed dependence on time and protein concentration; instability to heating; temperature and pH optimum. The production of T3 and rT3 from T4 was maximum at pH 6.5 and at pH 9.5, respectively, indicating that two different enzymic systems, a 5- and a 5'-monodeiodinase, might be involved in the deiodination of the tyrosyl and the phenolic ring of T4 in dog kidney.     

Control of infection in general practice: a survey and recommendations.

Twenty general practices in four areas in Britain were surveyed to establish their needs for and practices of sterilising and disinfecting equipment. Of the 327 items of equipment and instruments examined in the survey, 190 were satisfactorily decontaminated, 100 were treated in a way judged to result in doubtful decontamination, and in 37 cases treatment was considered unsatisfactory. Decontamination apparatuses (autoclaves, hot air ovens, and hot water disinfectors) were generally in good working order, but the use of chemical disinfectants was often inappropriate. Recommendations were made on appropriate methods of decontamination for various items in common use in general practice. By virtue of the large numbers of patients treated by general practitioners there is a substantial possibility of transmitting infection; having appropriate methods for decontaminating instruments and equipment is therefore imperative.     

Production of the mutant E strain of Rickettsia prowazekii by mutagen exposure

The possibility of obtaining the mutants of R. prowazekii, strain E, by exposing these organisms to the action of N-methyl-N-nitro-N-nitrosoguanidine was studied; this substance, used in doses of 5-10 micrograms, showed a mutagenic effect on rickettsiae suspended in physiological saline, after their exposure for 10-20 minutes at 37 degrees C. The mutants thus obtained proved to be resistant to erythromycin and rifampicin and were characterized by heterogeneity in the degree and stability of their antibiotic resistance. The effectiveness of selection was increased if mutagen-treated rickettsiae were selected after the first passage in chick embryos. The induced mutants differed from the original rickettsial strain by their lower infectiosity for chick embryos.     

Immunotoxicotherapy: protective effect of anti-colchicine antibodies in acute colchicine poisoning in rabbits and mice

Anti-colchicine antibodies are able to neutralize toxic effects of colchicine after acute intoxication in rabbits and mice. The protecting effect is demonstrated by active immunization (rabbits) or passive immunization (mice). These data suggest that the immunotoxicotherapy may be useful for compounds (colchicine) with intracellular action.     

Platelet-activating factor. Evidence for 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine as the active component (a new class of lipid chemical mediators).

A glyceryl ether containing phosphoglyceride, 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (Ac-GEPC), has been shown to have a biological activity indistinguishable from that of naturally generated (rabbit) platelet activating factor (PAF). Its biochemical and biological properties so closely parallel those of naturally occurring PAF that we propose they are one and the same compound. Both PAF and AcGEPC could be converted to an inactive form through base-catalyzed methanolysis and restored to 100% functional activity by reaction with acetic anhydride. The synthetic lipid, AcGEPC, elicited 50% secretion of serotonin from rabbit platelets at a level of 10(-10) M (based on phosphorus). A propionyl derivative had somewhat comparable activity towards platelets, whereas the butyryl homologue was some 7-fold less active and the stearoyl derivative was inactive. These short chain acylglyceryl ether phosphoglycerides represent an entirely new, potent and unique class of lipid chemical mediators. 1-Acyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (AcLL) also exhibited activity towards platelets but was some 200-fold less active than AcGepc. the propionyl lysolecithin behaved quite similarly to AcLL, but butyryl and stearoyl lysolecithins showed no activity.     

Trial of an erythrocyte antigenic diagnostic agent for detecting antibodies to Coxiella burnetii

A new method for the preparation of Q-fever erythrocyte antigenic diagnosticum, adaptable to large-scale production, has been developed, and the diagnosticum thus obtained has been found to be highly specific and sensitive. The combined use of the complement fixation and passive hemagglutination tests enhances the effectiveness of the serological study, as it not only ensures a more complete detection of antibodies to C. burnetii, phase I, in humans and cattle, but also gives more precise indications on the time of infection.     

New data on abiogenic synthesis of prebiological compounds in volcanic processes

Volcanoes were deduced to be high-productive generators of complex organic compounds. Ash-gas clouds produced by volcanic eruptions can be considered as many-kilometer chemical reactors with a wide range of temperatures and pressures, powerful electric discharges and a large catalytic surface. In the eruption products investigated, nitrogen-containing components of nucleic acids of uracil type, metal complexes of porphyrins and porphyrins in the metal-free form and polycyclic aromatic hydrocarbons have been found. In all, 54 carbon-containing compounds have been identified in the volcanic juvenile ash and in volcanic bombs and 13 groups of carbon-containing compounds whose composition is yet unidentified have been found.