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Biomedical subjects

P Groza

Publications and source records attributed to P Groza.

At least 19 recordsLinked to original sources
PubMed1991

Digestive histochemical reactions in rats after space flight of different duration.

Different histochemical reactions were searched in the digestive tract of rats that flighted on Soviet biosatellites, 5, 7, 13, 14 and 18 1/2 days (2). Space flight decreased glycoprotein (GP) content of sublingual glands and of gastric and intestinal mucosa, and increased reactions for leucin-aminopeptidase (LAP) and acid phosphatase (ACP) of the small intestine. These responses were in relation with the duration of the flight. For searching some possible mechanism by which they occurred, same investigations were done in rats submitted at soil level to a contention hypokinesia (HK), for mimicking space flight. After HK, similar histochemical responses were founded as after the true flight. The evolution of histochemical responses paralleled the corticosterone hypersecretion, suggesting a causal correlation, but they were also the same in adrenalectomised rats. Effectory hormonal pathways are thus further to be searched, as well as a correlation with the intermediary metabolism, as a similar evolution was founded in pancreatic, insulin secreting, B cells.

Animals↗
PubMed1978

A method for continuous electrocardiodynamic monitoring.

A new method is presented for the monitoring of cardiac time intervals, e.g. in clinical and industrial work investigation. The methods yields 'on-line' the electrocardiodynamic time profile during rest as well as effort, and has applications in health care, sports and occupational medicine. By means of analog processing of an electrocardiographic signal, ear densitogram and beat-by-beat display of the measured cardiac time intervals as amplitude-modulated pulses, an 'electrocardiodynamic time profile' is obtained. In order to estimate the accuracy and the limitations of the method, a comparison with computerized methods was performed. In an ergonomic experiment carried out by a Romanian-Swedish research team, analog and digital methods for the detection of cardiac time intervals showed good agreement.

Adolescent↗
PubMed1975

Variations in the activTY OF SOME BRAIN AND PLASMA ENZYMES UNDER THE INFLUENCE OF +Gz acceleration.

The present paper refers to the activity of some enzymes associated with the cellular cytomembranes in the plasma and brain of guinea pigs exposed to the action of repeated +10Gz acceleration. Immediately after the last run, diminution of enzymatic activity in the brain supernate ran parralel to a rise in plasma enzymatic activity. Variations in enzymatic activity suggested the liberation of enzymes connected with the neuronal organelles, perhaps consequent to alterations in the permeability or structure of the neuronal cytomembranes. These alterations might also be interpreted as being accompanied by permeabilization of the blood-brain barrier, with release of enzymes from the neuronal structures into the plasma. Changes in the permeability of the neuronal membranes might be attributed to several factors: cerebral hypoxia following the hemodynamic and ventilation alterations induced by hypergravitation, the influence upon the membrane permeability of hormones released in excess under the stress of acceleration, and the strain to which the central nervous system neurones are subjected by the multitude of afferent impulses with a starting point in the various types of receptors stimulated by hypergravitation.

Acceleration↗
PubMed1975

Effects of 2200-m hypoxia on glucidic metabolism.

Rats exposed for different intervals (1, 3 and 6 hours, the first day, and then 6 hours a day for 9 days) to a 2200-m hypoxia presented metabolic changes demonstrating an anaerobic glucose utilization. Thus, in accordance with other authors, at different depressurization values the liver homogenate had increased lactate and pyruvate concentrations, decreased NAD and NADH2 concentrations and a decreased ATP formation, demonstrating the inefficient glucide metabolization. These modifications were evident in the first hours of depressurization, but did not occur under acclimatization during the 9 days of exposure. The LDH concentration remained practically unchanged, which might be explained by its explained by its excessive presence in relation to the normal exercise solicitation. A urinary hypercompensatory alkalinization was also recorded.

Adenosine Triphosphate↗
PubMed1975

Glucidic and lipidic metabolic changes in rats induced by irradiation and the effect of adrenalectomy.

In experiments on X-irradiated rats (1000 R) the hepatic glycogen, total lipids, phospholipids content, and plasma glucose, cholesterol and beta-lipoprotein concentration were determined in intact and adrenalectomized animals. It was confirmed that irradiation produces a hepatic glycogen and blood glucose increased concentration. The glucidic metabolic response on irradiation is diminished by adrenalectomy. The adrenalectomy-induced modifications in the lipid metabolism of irradiated rats are more inconstant, which corresponds with its relative independence from glucocorticoid hormones.

Adrenal Cortex↗
PubMed1975

Plasma corticosterone secretion in rats after irradiation.

In this material it was confirmed that the irradiated rats present a two-phase corticosterone hypersecretion. The responses are greater to higher doses of irradiation (700 R as compared with 500 R). The postirradiation hyperglycemia is not correlated with the corticosterone hypersecretion, having its peak value a day before.

Adrenal Cortex↗
PubMed1975

Hypergravitation and sympatho-adrenergic reactivity.

The cardiac frequency and adrenal and urinary catecholamine content were investigated on 10-minutes centrifuged rats (+6 Gz). It was found that the heart responds in an individual manner, with a general tendency to tachycardia. Under the same conditions after 1 1/2 minute the adrenal noradrenaline response was absent, after 3' and 6' the adrenal noradrenaline content was augmented and the adrenaline one diminished, and after 10' the response vanished. Hypergravitation does not change the urinary noradrenaline elimination collected after 10 minutes of centrifugation, but that of adrenaline is augmented in one of the two explored animal groups. The difference between the two groups may be explained by the great individual variations, as results from the cardial frequency (appreciated by teleelectrocardiogram). The environmental stress produces similar but more reduced catecholamine modifications.

Acceleration↗
PubMed1975

Effects of mild hypoxia (2200 m) on catecholamine and corticosterone secretion.

In experiments carried out in male Wistar rats submitted in laboratory to a 2200-m depressurization the urinary noradrenaline and adrenaline elimination, as well as the plasma corticosterone level were investigated. In rats previously submitted 12 days only to the environmental stress the true depressurization (7 days) produced a relatively increased noradrenaline and adrenaline elimination. A similar increased catecholamine output was observed in rats submitted directly to hypoxia. The plasma corticosterone level was unmodified by hypoxia of the same value.

Adrenal Glands↗
PubMed1975

Daniel Danielopolu.

Explore the source record for details and available documents.

History, 20th Century↗
PubMedDate not supplied

Na+ and K+ dependent ATP-ase and structural modifications in hypokinetic rats.

In rats the hypokinetic state obtained by restraint in special cages, produces after 30 days, a marked decrease in Na+ and K+ dependent ATP-ase in the skeletal muscle. After 15 days hypokinesia the enzymatic content of the investigated tissues did not change. In the left cardiac ventricular muscle Na+ and K+ dependent ATP-ase decreased after 15 days and particularly after 30 days hypokinesia. These changes were brought about by the hypofunctional state of both muscles, which also produced structural alterations. In the skeletal and cardiac muscles electron microscopy revealed fibrillar atrophy and mitochondrial alterations typical of an affected function. In the cardiac muscle, in which these changes were more accentuated, the dissociation of the intercalar disc was also noted, aspects partially described by others.

Adenosine Triphosphatases↗
PubMedDate not supplied

Digestive structural modifications in rats submitted to 15 days of hypokinetical conditions.

Restraining rats for 14 days in special cages in order to determine a hypokinetical state decreased mucopolysaccharide secretion in submaxillary glands and gastric mucosa. In the small intestine and in the colon, concomitantly with an enzymatic (leucine-aminopeptidase and acid phosphatase) hypersecretion as results from specific histochemical reactions. These modifications show maximum intensity at the end of the interval. The corticosterone plasmatic level determined in the same interval also increased, suggesting this way to a causal relation. The histomorphological changes presented delayed reaction. This material is in accord with our previous investigations as well as with some literature data.

Acid Phosphatase↗
PubMedDate not supplied

Plasma renin activity, aldosterone and cortisol in relation with postural changes in dogs.

Experiments were carried out in six dogs anesthetized with chloralose, fixed on a tilting table and moved from the supine to the vertical posture. In one dog this postural change was done after cutting both Hering nerves, and in another one after bilateral nephrectomy (BN), these experiments being orientative. Changing the supine to the vertical posture was followed by increase in plasma renin activity (PRA) and in aldosterone and cortisol plasma concentration (p.c.) Between PRA and aldosterone p.c., there was a slight correlation, but between aldosterone and cortisol this was evident. Therefore it may be supposed that aldosterone hypersecretion is produced by ACTH hypersecretion, a common stimulatory pathway for both hormones. This stimulatory mechanism is sustained by the orientative experiment on dogs, with BN, in which supine to vertical changed posture was followed by an important aldosterone hypersecretion despite minimal values of PRA.

Aldosterone↗
PubMedDate not supplied

Coagulation and fibrinolysis in rats after confinement hypokinesia.

Our previous experiments (14) (15) dealt with the dynamic of the fluid-coagulant equilibrium in rats after exposure to confinement hypokinesia (CHK) at different time intervals, 1, 3, 7, 21, 28 and 35 days. We found a decreased Quiq and Howell time (QT and HT) in some relation with the time of exposure, with a tendency to normalization after 21 days. The same evolution was shown by the number of thrombocytes and of the euglobulin lysis time (ELT). In this work we prolonged the exposure to CHK for 60 days, an interval after which a series of other functional parameters significantly approached initial control values (16). We found an important approach to normal values also with the QT, HT, Elt and with the number of thrombocytes. Concomitantly, the plasma concentration of corticosterone (the principal glucocorticoid of rats), that increased over shorter intervals, approached also control values after 60 days of exposure to CHK. Nevertheless, it can not explain the changes of coagulability, because it decreases after adrenalectomy but the QT, HT and thrombocytes are already decreased. For these and other reasons it results that the relation of adrenal hormones to coagulation needs be further clarified.

Adrenal Cortex Hormones↗