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Biomedical subjects

R Bernat

Publications and source records attributed to R Bernat.

At least 37 records · Page 2Linked to original sources
PubMedDate not supplied

Experimental studies on osmotic mechanisms and vegetative regulations of intraocular hydrodynamics as well as the distribution of elecrolytes and amino-acids in refractive environments of the eye.

The studies were carried out on the influence of hyperosmolar loading with glycerol and hypoosmotic glucose, as well as on the effect of pharmacological stimulation of the adrenergic system after sympathetic decentralization of the eyes, and of the cholinergic stimulation, on intraocular hydrodynamics, and on the distribution of electrolytes and amino-acids in refractive environments. The results showed a dependence between the changes in blood osmolality and osmotic intraocular activity, and the secretion and flow of the aqueous humor, as well as the distribution of electrolytes and amino-acids. No specific, antagonistic influence of the adrenergic and cholinergic stimulation on the hydrodynamics and the distribution of electrolytes and amino-acids in refractive environments has been found. The opposite reactions to stimulation of adrenergic alpha or beta-receptors have been observed.

Amino Acids↗
PubMedDate not supplied

Catecholamines in the rat brain during hypoglycemic convulsions and coma.

The purpose of the study was to investigate the relation between the catecholamines: noradrenaline and dopamine in the rat brain on one hand and hypoglycemic convulsions and coma on the other. Concentrations of noradrenaline in the hypothalamus, brain stem and cerebral cortex were decreased during hypoglycemic convulsions and were lower during coma than those during convulsions. Dopamine concentration in the striatum was decreased during convulsions and coma. It was shown that the decrease in concentration of catecholamines was a result of hypoglycemia but not of insulin action itself. Clonidine- alpha 2 agonist accelerated occurrence and prolonged duration of hypoglycemic convulsions. Haloperidol-dopamine receptor blocker had no effect on the time of occurrence or duration of convulsions and coma. The results indicate that noradrenaline may exert an inhibitory influence on hypoglycemic convulsions. No evidence has been provided to support involvement of dopamine in the control of hypoglycemic convulsions and coma.

Animals↗
PubMedDate not supplied

Effect of proteolytic activation on intraocular hydrodynamics the pressure of O2, CO2 and pH in the aqueous humor.

The effect of proteolytic activation on the tonographic indices and secretion of the aqueous humor was studied. It was found that active peptides rise the secretion of intraocular fluids increasing the permeability of capillary plexuses and decreasing the metabolic processes in the structures secreting the aqueous. They may perticipate in haemodynamic and hydrodynamic intraocular autoregulation.

Animals↗
PubMedDate not supplied

Glutathione concentration and peptidase activity in the lens after exposure to microwaves.

This study was undertaken for observation of early changes in glutathione concentration and the activity of carboxypeptidase A and aminopeptidase in the cortex and core of the lens as well as for determination of the cumulating effect of microwave energy after repeated exposures to microwaves. Experiments were carried out on New Zealand rabbits. The control group was compared to experimental groups exposed every day for 5 minutes to microwave irradiation of the eyeballs at power densities of 5 X 10(-3) W/cm2 and 10 X 10(-3) W/cm2 during 10, 20 and 30 days. Differences were found between the control group and the groups of animals exposed to microwaves in which the glutathione concentration in the cortex and core of the lens was decreasing with time in proportion to the number of exposures. Parallelly to the number of days of exposure to microwaves the enzymatic activity of carboxypeptidase A and aminopeptidase increased in the cortex of the lens. The observed changes demonstrate cumulation of the absorbed microwave energy leading to changes in the permeability of the capsule and membranes of lenticular fibres which lead to secondary metabolic disturbances in the lens of the eye.

Aminopeptidases↗
PubMedDate not supplied

The effect of arfonad on blood proteins and nitrogen components in experimental shock.

In experiments performed on anaesthetized dogs the effects of dye shock and peptone shock on changes in serum osmolality, haematocrit value, amino acid level in serum and erythrocytes, and serum total protein and protein fraction levels were determined. In further experid (0.1 mg/kg). It was found that Arfonad exerts an inhibitory effect on the shock-induced reduction in the serum osmolality, plasma volume and on the albumin level.

Animals↗