Acta biologica et medica Germanica最新文献

The partially inbred strain of BB-Wistar rats showed a varying incidence of the insulin-dependent diabetes-like syndrome. The serological typing of a large sample of BB rats verified the homozygosity for the RTlu haplotype, whereas its parental non-inbred Wistar stock segregated for RTlu and RTla haplotypes. The histogenetical typing of BB rats by skin grafting showed a significantly prolonged rejection of grafts from RTla donors unusual in other RTlu recipients. The presumption of some recombinational or mutational events in the RTl haplotype of BB rats was not verified by the simple F1 skin grafting test from LEW.1U/RTlu standard/donors to F1/LEW X BB/recipients. Skin grafts survived permanently. When trying to get a clear-cut answer whether the RTlu haplotype is associated with the spontaneous occurrence of diabetes in F2/LEW X BB/ X /LEW X BB/hybrids, only 7.4% of RTlu homozygotes were found among 359 weaned animals. Moreover, the partial strain of BB rats became extinct with the F1 generation mainly due to an infection by the mycoplasma. A new sample of outbred BB rats with a low incidence of spontaneous diabetes was found as homogeneous for the RTlu haplotype, too. Preliminary results of typing these rats for the secondary antibody response to pig insulin indicate the low responsiveness contrary to the results given earlier for the RTlu typing strains as high responders. All these results support the idea that the RTlu haplotype of the BB rats might be a variant carrying some mutational change(s) at the RTl.B region.

By acid extraction, ethanol precipitation, affinity chromatography on 4-phenylbutylamine-Sepharose 4B and gel filtration on Sephadex G-100, calf liver neutral proteinase was purified. The purified enzyme was electrophoretically homogeneous and over 2000 times more active than the starting homogenate. The molecular weight, determined by SDS electrophoresis, was calculated as 27000. The pH optimum of the enzyme for whole calf thymus histones and N-benzoyltyrosine, ethyl ester (BTEE) was at 7.0 and 7.0-7.5. The Km value for histones was 2% and for BTEE 1.66 mM. The enzyme was strongly inhibited by soya-bean trypsin inhibitor and leucocyte intracellular I-1A inhibitor and less by alpha 1-antitrypsin and leucocyte inhibitor I-1B. The enzyme hydrolyzed only selected protein substrates, such as total thymus histones, Lys-rich histones, nucleoprotein and substance P, but not Arg-rich histones, hemoglobin and casein. The enzyme showed chymotrypsin-like properties by cleavage of substance P at the carboxyl groups of phenylalanine and leucine.

The effects of DL-tryptophan on photic evoked potentials (photic after discharges--PhNE, photic recruitment--PhR, photic evoked primary potential--PhEP) and basic activity of EEG were investigated in freely moving rats with chronically implanted electrodes in various areas of cortex. DL-tryptophan increased the number of PhNE potentials and particularly the number of NE potentials per answered lightflashes (NE/bLB). The effects depend on dosage of DL-tryptophan. The double impulse stimulation confirmed these results. The power spectral show an increased synchronization of the background EEG activity. The results are discussed in connection with local serotoninergic effects and influences on vigilance by 5-hydroxytryptamine.

The described analysis of physiological time series gives an example of how the relations between such series can be computed. We had performed force-varied isometric hand-grip contractions. After testing the corresponding prerequisites we investigated the interrelations between the force-induced responses of heart rate, blood pressure, pulse-transit time and force.

The effect of the memory improving substance methylglucamine orotate (MGO) on intracranial self-stimulation was investigated in rats. Self-stimulation (0.2 mn square pulses; 100 Hz frequency; 400 mn chain; 100-300 micro A current) was performed using electrodes in the lateral hypothalamus. MGO was administered intraperitoneally in doses of 112.5 mg/kg and 225 mg/kg or intraventricularly in a dose of 225 micrograms per rat. In chronic experiments, daily intraperitoneal injections of 225 mg/kg MGO were given during 10 days. The results show that intracranial self-stimulation is scarcely influenced by a single injection of retention improving MGO doses, but increased significantly by repeated MGO application.

The effect of trans fatty acids and essential fatty acid deficiency upon the activities of cholinesterase and monoamine oxidase in livers, hearts, brains and lungs of rats was studied. This study was performed using three groups of male albino rats. Two out of these three groups were fed essential fatty acid low diets containing 10% hydrogenated coconut oil (HCNO) or margarine stock (MS, partially hydrogenated soybean oil) while the third group was fed an adequate supply of essential fatty acids through a diet containing 10% corn oil (CO). In the group of rats fed HCNO the activities of cholinesterase and monoamine oxidase in their livers, hearts, brains and lungs were not significantly different from those of the control group fed CO. In the group of rats fed MS, the activity of cholinesterase was significantly decreased in the livers, hearts and brains, but not affected in the lungs, while the activity of monoamine oxidase was significantly decreased in the livers and hearts but not affected in the brains and lungs as compared to the control group fed CO. The levels of serum total lipids, total cholesterol and triglycerides were elevated in both groups of rats fed HCNO or MS than in the group fed CO, but this elevation was more highly significant in the group fed MS than in the group fed HCNO.

The variability of visually evoked potentials (VEP) during spontaneous changes of behavioural activity was investigated in freely moving rats with electrodes in the visual and frontal cortex, olfactory bulb and other brain structures. Averaged VEP were recorded and compared during periods of characteristic behaviour types like drowsiness, relaxed wakefulness, attentiveness, grooming and exploratory behaviour. These behavioural patterns, which are clearly distinguishable by observation, were characterized by a certain degree of visually evoked afterdischarges, recorded movements, EEG-patterns and mean respiration rate. The evaluation of early components of the VEP from single recorded samples and of the correspondent momentary respiration rate (respiration intervals) revealed strongly negative correlations. In general, the increasing behavioural activity is characterized by a decrease in the amplitudes of VEP-components, inversely correlated to the log of momentary respiration rate. During drowsiness and enhanced attentiveness, certain components are increased. During strong movements and distraction of attention (e.g. intensive scratching and licking) the VEP-components were decreased stronger. The negative complex around 62 ms increased during certain forms of behavioural activation and locomotion. The VEP-component N31, the respiration rate, and the quotient N31: N61 were found suitable parameters to characterize certain types of behaviour in comparison to relaxed wakefulness.

Respiration of washed ejaculated bull spermatozoa with exogenous succinate is drastically increased after a sudden cooling of spermatozoa (cold shock). Loss of intactness of the cellular membrane occurs in a small temperature range between about 16 degrees C and 8 degrees C. A low cooling rate in critical temperature range connected with a sufficient equilibration time at this temperatures strongly restricts the damage of the spermatozoal membrane.

Subsequently to a hypoxic exposure of adult rats the stimulus induced release of dopamine from striatum slices in inhibited for several days. Depending on the treatment with piracetam the restitution of this inhibition is accelerated manifold, though piracetam does not prevent the acute effect of hypoxia on dopamine release. The particular hypoxia related vulnerability of the potassium evoked dopamine release and the time course of piracetam effect obviously point to drug induced anabolic processes rebuilding vesicle storage sites.