Biomedica biochimica acta最新文献

Groups of each 8 male Long-Evans rats were treated with 1 or 10 micrograms/kg LHRH intraperitoneally and compared with control rats which received the vehicle fluid (NaCl-solution). Ambulatory activity in an open field (OF), entrance to central fields and the mobility index were significantly decreased by both doses. Correspondingly, wheel running and movement velocity were significantly decreased. A further group of 8 rats with chronically implanted electrodes which was habituated to sessions showed an increase of slow-wave sleep and a significant reduction of waking and active states with maximal expression 45 min after ip application of 10 micrograms/kg LHRH. Paradoxical sleep was slightly reduced. Sleep-wakefulness cyclograms showed increase of a sleep phase duration to 175% and of single slow wave sleep phase duration to 140% after LHRH. Phases of drowsiness were also prolonged.

A new method for the preparation of a neoglycoprotein (chemically mannosylated bovine serum albumin, D-Man.BSA) is described using the homobifunctional reagent divinylsulphone.D-Man.BSA purified by affinity chromatography on ConA-Sepharose 4B shows microheterogeneity as demonstrated by immunoaffinity electrophoresis with free ConA in the first-dimension gel. The dissociation constant K for the neoglycoprotein-ConA complex has been calculated to be 2.5.10(-5) M. Biotinylated D-Man.BSA is a useful reagent to detect carbohydrate binding proteins of L1210 leukemia cells on blots. The neoglycoprotein labelled with colloidal gold may be used to demonstrate L1210 cell surface D-Man binding proteins by preembedding electron microscopy.

Long-Evans hooded rats were not able neither to reach criterion of active avoidance tasks in a Y-maze and in a jump test, nor in brightness discrimination after lesions of the NRTP without preoperative experience in these tests. After preoperative consolidation of active avoidance, the retention of Y-maze avoidance performance was zero and of jump test avoidance at 25%. The Y-maze avoidance was again relearned except in the task with 2:2 alternation of goals whereas retention of brightness discrimination was not affected. In the jump test, avoidance relearning was evidently retarded. Ambulatory and exploratory behaviour in the open field were significantly reduced after NRTP lesions. The NRTP is evidently involved in the establishment and control of goal-directed behaviour.

Almitrine bismesylate simulates the effects of arterial hypoxia in producing a specific and long-lasting excitation of the peripheral arterial chemoreceptors. Previous work has shown that almitrine produces a diuresis and natriuresis when given intravenously to anaesthetised rats in a stable mannitol induced diuresis. This response is abolished by glossopharyngeal nerve section implying that it is afferently mediated via the carotid body chemoreceptors. We have studied further the efferent limb of this response. The diuresis and natriuresis occurs without significant detectable changes in effective renal plasma flow and glomerular filtration rate suggesting that it is produced mainly by inhibition of renal tubular sodium and water reabsorption. Almitrine produces a diuresis and natriuresis in rats after bilateral nephrectomy and transplantation of a kidney from a donor rat. This effect is not therefore efferently mediated by the renal nerves and probably involves a humoral agent. Almitrine produces a diuresis and natriuresis in rats after bilateral adrenalectomy and in rats with congenital hypothalamic diabetes insipidus indicating that neither adrenal hormones nor changes in antidiuretic hormone levels are implicated.

Pharmacokinetic studies with the arterial chemoreceptor stimulant almitrine (100 mg per os) were performed in 12 healthy volunteers and 8 patients with essential hypertension stage I in order to evaluate the suitability of the drug for physiological tests. The parent compound was determined gas-chromatographically. Almitrine was absorbed with maximal serum levels after 1.8 +/- 0.4 h in healthy volunteers and 1.5 +/- 0.3 h in patients. The elimination proceeded biexponentially with terminal half-lives from 14.6 to 43.4 h in volunteers and 12.5-45.0 h in patients. Further characteristics were large distribution volumes (16.1 +/- 4.5 ml/g in healthy volunteers, 13.9 +/- 4.7 ml/g in patients) and large interindividual variations of all pharmacokinetic parameters by a factor of 2 to 6. Significant differences between healthy individuals and patients were not observed. The drug was well tolerated. The pharmacokinetic properties of almitrine should be included into its evaluation as a test compound.

The S'-subsite specificity of the endoproteinase Glu/Asp-C from Actinomyces sp. was studied by acyl transfer reactions using amino-acid- and peptide-derived nucleophilic amino components. The following results were obtained: 1. The enzyme prefers amino acid amides with hydrophobic side chains in P'i position. In addition, positively charged functions in this position favour S'-P' interactions significantly. 2. Stereospecific binding is a prerequisite for nucleophilic efficiency. 3. Dipeptide amides are more efficient amino components in comparison to free dipeptides whereas oligoglycines show a poor nucleophilic behaviour independent of chain length.

Administration of stobadine, a cardioprotective substance in investigation prevents a decrease in the content of protein SH groups and glutathione in hearts of rats treated with high doses of isoproterenol (ISO) (30 mg/kg). Moreover, stobadine also attenuated the increase in the content of malondialdehyde and activities of catalase and glutathione reductase as well as a diminution in the GSH/GSSG ratio observed in heart mitochondria isolated from ISO-treated animals. Since stobadine may be considered as a scavenger of reactive oxygen species (ROS), the above effects of the latter substance support the assumption about a possible involvement of reactive oxygen species (ROS) in some processes initiated by administration of ISO in doses inducing cardiac hypertrophy. However our results also indicate that ROS-mediated processes are not necessarily involved in the mechanism of induction of cardiac hypertrophy itself.

Alpha-amylase from Thermoactinomyces vulgaris (strain 94-2A) was purified by cellulose chromatography and gel-chromatography on Sephadex G-75 and subsequently characterised. The enzyme shows a single band in the polyacrylamide gel electrophoresis (PAGE). The isoelectric point was determined to be pH 5.4, and the molecular mass was estimated as 53,000 Dalton by PAGE. The amino acid composition was determined; it shows characteristics of other microbial alpha-amylases. A comparison of the N-terminal sequence with that of other alpha-amylases shows a homology of 66.6% to Taka-amylase. The pH-optimum for the alpha-amylase activity is 4.8 to 6.0 and the temperature optimum 62.5 degrees C. The heat inactivation was investigated under different conditions (temperature, time, Ca2+, EDTA).

Dichloromethane sensitizes the myocardium to arrhythmia development in response to catecholamines. The effects of acute dichloromethane exposure (3.1, 6.2 or 12.4 mmol/kg) on cardiovascular actions of epinephrine (1 or 4 micrograms/kg iv) and norepinephrine (2 or 10 micrograms/kg iv) in the urethane-anaesthetized rat model was investigated. Hypertensive epinephrine effects as well as reflex bradycardia after epinephrine and norepinephrine injections were augmented in dichloromethane-exposed rats. Moreover we observed an enhanced negative dromotropic epinephrine action. The transient T-wave elevation after catecholamine injection was markedly increased in animals treated with 12.4 mmol/kg dichloromethane. The results show that dichloromethane exposure modifies cardiovascular actions after catecholamine administration. The release by dichloromethane of endogenous catecholamines could play a role in the manifestation of these effects.