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Biomedical subjects

P Groza

Publications and source records attributed to P Groza.

At least 91 records · Page 5Linked to original sources
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↗
PubMedDate not supplied

Histochemical alterations in the digestive tract of rats after 13 days of flight in the "Cosmos 1887" biosatellite.

In rats recovered after 13 days of cosmic flight a diminution of acid and neutral glycoproteins was observed in the gastric mucosa and proximal segments of the small intestine: the decrease was less evident in the sublingual glands and colon. Leucine aminopeptidase and acid phosphatase in the small intestine were intensified. No significant changes were observed in the other enzymes investigated. Acid phosphatase showed a more intense activity in the endocrine pancreas B cells. The alterations observed after 13 days of flight in the "Cosmos 1887" biosatellite are significant but less marked than after 18 days of flight, and more accentuated than after 5-7 days of flight.

Animals↗
PubMedDate not supplied

Blood coagulation and fibrinolysis in hyperthermic rats.

Exposure of rats to an environment of +40 degrees C that increases central (rectal) temperature to about 40 degrees C, importantly decrease the number of thrombocytes, the blood coagulation (the Quick time and Howel time) and euglobulin lysis time (ELT). In order to search for the mechanism responsible for coagulability and fibrinolysis we studied the relations of these changes with the sympatheticoadrenergic system and with the adrenal hormonal secretion. Some parameters were thus explored after adrenalectomy and under the influence of a beta-blocking agent, Eraldin. Adrenalectomy moderately reduced these decreasing effects, excepting the ELT. Eraldin has a contrary effect. Adrenalectomy acts by suppressing the corticoid reaction and by diminishing the catecholamineones. Since Eraldin influences coagulation and fibrinolysis in an opposite sense than adrenalectomy, it may be concluded that catecholamines do moderate the effect of heating, inhibiting and not stimulating circulation, as assumed. On the contrary, corticoids (gluco- or mineralo-) contribute to the effect, influencing coagulation in hyperthermia. Both influences are slight, not determinant. Supplementary explorations revealed that repeated daily exposure for 1-2 or 3 weeks, simply in the cages in which hyperthermia was subsequently produced, decreased also the number of thrombocites, the QT and the ELT, especially the last one. The HT was less influenced. It results that these exposures, produced effects similar with hyperthermia. Heating rats after these daily repeated exposures does not influence these already changed parameters.

Adrenal Glands↗
PubMedDate not supplied

Effects of a seven-day hypokinesia on the digestive tract of nonpregnant and pregnant rats.

Hypokinesia (HK) produced by a 7-day contention of pregnant rats in small cages is followed by a discrete decrease of PAS reaction for glycoproteins in the submandibular and sublingual glands, in the mucosa of the stomach, duodenum, small intestine and colon, and also by a small but evident increase of that for leucineaminopeptidase and acid phosphatase in the duodenum and in the intestine. The moderation of these reactions may be explained by the small interval of contention, and not by pregnancy, because the changes are similar in male rats after the same interval. After a longer interval, these reactions change in the same manner but they are more evident, as results from our previous studies. They are not connected with a corticosterone hypersecretion (the principal glucocorticoid in rat) because adrenalectomy does not influence them as results from our previous research. HK increases the 4 and 5 isoenzymes of lactic dehydrogenase (LDH) in the stomach. In the small intestine appeared only the LDH 4 and 5 isoenzymes, HK increases LDH5 isoenzyme. Adrenalectomy increases all LDH isoenzymes of gastric mucosa, and in the small intestine all five fractions appeared, but with a slight activity of LDH 1 and 2. This relation between adrenal hormones and these isoenzymes must be further studied, especially after HK. After a 7-day HK, nonpregnant female rats present an augmented total gastric acid output (TAO), as previously found by us in males. After adrenalectomy this acid hypersecretion disappeared. Even smaller values for TAO were found. Pregnancy considerably increased TAO which may be due, as we have already found, to a blood pH decrease. After HK this hypersecretion decreased remaining nevertheless great. Progeni born of rats submitted to HK have, after 30 days of life, an augmented TAO. Parts of this research were carried out in order to reproduce by HK, at ground level, the 5-day orbital flight conditions of the soviet Cosmos 1514 biosatellite containing pregnant rats in which we studied some identical parameters.

Acid-Base Equilibrium↗
PubMedDate not supplied

Histochemistry of the gastrointestinal tract in pregnant rats subjected to cosmic flight and in their progeny (Cosmos 1514).

Investigations were carried out in the digestive tract of pregnant rats submitted to 5 days orbital flight, as well as in rats aged 30 and 100 days, to which the pregnant experimental rats had given birth. The flight produces, in pregnant rats, a mild reduction of the glycoproteins of the salivary glands, of the gastric mucosa and the goblet cells of the small intestine, as well as an augmented activity of some intestinal enzymes. The progeny born after flight presents at 30 days a mild decrease of the glycoproteins in the sublingual gland and stomach and a slight increase in the activity of some enzymes in the small intestine. In 100-day-old rats, the differences between control and experimental group are not significant.

Animals↗
PubMedDate not supplied

The "involuntary postcontraction" mechanism or the postcontractile elastic restitution.

Unquestionable experimental proofs are brought forward in support of the non-cortical origin of "involuntary postcontraction". The mechanism of this phenomenon is purely passive and it originates in the elastic component of the muscular organ. Far from inducing the postcontractile event, cortical induction brakes it. The results obtained up to now enable the authors to consider that the analysis of postcontraction provides quantifiable information of great practical importance on the type and momental functional state of human nervous system.

Animals↗