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Biomedical subjects

R Cârmaciu

Publications and source records attributed to R Cârmaciu.

12 recordsLinked to original sources
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↗
PubMedDate not supplied

The adaption to environmental factors: hazard or programme.

Any living structure, from cell to the entire organism, can adapt to internal or external factors only by triggering pre-existing mechanisms. All these mechanisms have a morphological support programmed within foetal inactive genes or adult genes with low activity. These genes are activated by a chain of reactions that usually starts with perceiving the stimulus at the membrane level and finishes with the synthesis of some proteins (enzymes, membrane receptors, etc.). The adaptative changes of the enzymatic and structural register would be impossible without the activation of genes other than those operating in normal condition. It is obvious that the same pre-existing genetic mechanism also functions in myocardial hypertrophy or neoangiogenesis. Actually, "a genetic orchestra" is ready to perform at a given moment the new tone suggested by the ever changing condition under which the myocardial fiber acts. However, the concept of programmed adaption has not only a theoretical value; in medical practice, the prediction, prevention and treatment of ischemic heart disease will benefit from the theoretic support of understanding the cardiac adaptative behaviour. It is obvious that this adaptation programmes cannot always save the heart from necrosis and the subject from death due to fatal arrhythmias or cardiogenic shock.

Adaptation, Physiological↗
PubMedDate not supplied

The role of the Gregg phenomenon in cardiac performance.

The Gregg phenomenon has not, yet, a full and complete explanation. We are allowed to consider it a "garden house"-like effect. Positive inotropic factors are released as a consequence of "shear stress" phenomenon following an increased coronarian flow. In our study, it is more probably a "garden house"-like effect that causes a sarcomere stretch. This could explain the increased left ventricle performance found, in some circumstances, in our study. We used the data obtained by coronarography in 22 patients carrying various degrees of coronarian obstruction and we assessed the left ventricle performance during the repeated injection of contrast medium, that increases the pressure in the coronarian bed. The results obtained support the theory regarding the Gregg effect but do not allow us to consider this effect as a fundamental determinant of the cardiac performance.

Coronary Angiography↗
PubMedDate not supplied

Effects of a high-tension electric field on the secretion of antidiuretic hormone in rats.

White male Wistar rats exposed a single time for 120 minutes to the action of an electric field of 100 kV/m and 50 Hz present a very important increase of the plasma concentration of antidiuretic hormone (ADH). In the case of a 360-minute exposure a 30 per cent reduction of the diuresis as compared with the control takes concomitantly place.

Animals↗
PubMedDate not supplied

The sympatho-adrenergic response in hyperthermia.

The sympatho-adrenergic reaction was investigated in heated rats under the influence of a ganglioblocking agent--hexamethonium. The overheating at a 40 degrees environmental temperature produced in a relatively short interval (after 157 min on an average) the death of the animals. An initial bradycardia was followed by a tachycardic phase. In the prelethal phase there appeared bradyarrhythmia produced by conductibility troubles and activation of ectopic ventricular centers. The survival time was not influenced by hexamethonium in spite of its hypothermic action. In blood, heating produced an increased concentration of noradrenaline and adrenaline. Hexamethonium, which reduced the rectal temperature, markedly decreased both blood catecholamines concentration. On this background heating likewise produced a relative increase of both blood catecholamines content. The catecholamines changes in adrenal glands presented less significant modifications.

Animals↗
PubMedDate not supplied

[The effect of continuous illumination and an inverse rhythm (light-darkness) on fibrinolysis].

The studies of chronobiology on biological phenomena revealed the existence of a human internal mechanism ("biological clock") which controls biological events according to each function of the body. Most of the programmed and genetically fixed rhythms can be changed and synchronized by external factors. Starting from these data and from our previous studies which emphasised an intradian rhythm of the proteolytic blood coagulation and fibrinolytic systems we observed the behaviour of the fibrinolytic system in modified environmental conditions (continuous illumination and inversed day-night rhythm). Our experiments were performed on 180 Wistar rats both male and female, submitted to continuous illumination and inversed rhythm for 1, 3 and 5 weeks. We studied plasma fibrinolytic activity (PFA) through euglobulin lysis time (ELT) at three different moments of the day: 8:30, 18:30 and 8:30 the next day. The study revealed intradian variations of PFA regardless of the type and time of submission. Thus: continuous illumination for 1, 3, 5 weeks determined a decrease of PFA (prolonged ELT) during the second part of the day, less important at 5 weeks. Inversed day-night rhythm for 1 and 3 weeks determined the same intradian behaviour of PFA but less important than continuous illumination. PFA variations in our experimental conditions suggest an alteration of its biological rhythm.

Animals↗
PubMedDate not supplied

[Fibrinolysis during pregnancy. The pre- and postpartal changes].

Our previous research as well as data in literature (Yuasas, Ishizawa M.--1992) emphasised increased plasma fibrinolytic activity (PFA) in women during labor. Starting from these data we have tried to observe plasma fibrinolytic activity studied through euglobulin lysis time (ELT) in women during pregnancy and after delivery. We studied 25 healthy pregnant women aged between 18 and 30 years which were tested in the seventh month, during labour and at 48 hours after delivery. Blood samples were taken from the antecubital vein by venous puncture. The study showed an increased PFA (shortened ELT) only during labor; in the seventh month and at 48 hours after delivery ELT had almost the same values.

Adolescent↗
PubMedDate not supplied

Blood and urinary catecholamine variations under the action of a high voltage electric field.

White Wistar male rats, weighing 150 +/- 20 g, adapted to the laboratory ambience during 12 days, were exposed to an electric field of 100 kV/m for 360 minutes in acute (once) or chronic experiment (12 days running). Urinary (nanogram h-1) and blood catecholamines (microgram/100 ml) showed a significant increase as compared to the controls, adapted to the ambience but not exposed to an electric field. The most accentuated increase was that of adrenaline in the acute experiment. In the chronic experiment the adrenaline response gradually failled.

Animals↗
PubMedDate not supplied

The effect of a high-voltage electric fiedl on neurosecretion and on certain diencephalic protein fractions in the rat.

Exposure of Wistar male rats to an electric field of 100 lV/m for 120 minutes produced intense mobilization of the neurosecretory material in the supraoptic and paraventricular nuclei and significant changes in some protein fractions of the hypothalamus, pineal body and neurohypophysis. The significance and possible mechanisms of these effects are discussed.

Animals↗