Romanian journal of physiology : physiological sciences最新文献

We have investigated the impact of POLYAS I and POLYAS II polyphenolic biopreparations - specifically separated and purified from Asclepias syriaca leaves, and characterized in vitro as cytotoxic and/or cytostatic agents - on the tumor generation process. A series of in vivo tests of their effect on the development of Guerin T-8 lymphotropic epithelioma and Walker 256 carcinosarcoma were conducted. In a first stage of preclinical trial we had used several tests meant to evaluate their antitumoural activity indices. The same tests were then used under similar experimental conditions in the solid tumoral systems mentioned. A comparative analysis of the antitumoral activity evaluation indices resulting from our tests with the reference indices set by the American and German preclinical screening programs pointed to their compatibility. Thus, we found similar values of mean tumoral regressions, of the ratio between mean tumoral weights of the treated and control groups, respectively, of the T/C products resulting from successive re-tests. Also T/C values resulting from retests were within the limits of admissible variability range. All those results highlighted the antineoplastic pharmacotherapeutic effect of the polyphenolic biopreparations and also proved that effect to be replicable. The qualitative evaluation of the pharmacodynamic action of those preparations was a condition for their further quantitative pharmacological evaluation in point of antitumoral therapeutic effectiveness in a preclinical stage.

The comparative study of the vascular effects of agmatine and L-arginine as physiological precursors of NO indicated the following: When administered intravenously, both vasoactive substances produced a decrease of the systemic blood pressure in rats and rabbits, diminished in the case of agmatine and suppressed in that of arginine by the previous administration of L-NAME. Myorelaxing vascular effects were obtained in isolated thoracic aorta rings, precontracted with phenylephrine and noradrenaline. Endothelium removal suppressed the myorelaxing properties of L-arginine, without affecting the effects of agmatine, both before and after administration of L-NAME or yohimbine. The persistence of the relaxing effects of agmatine after NOS and guanylate-cyclase inhibition with methylene blue excludes the participation of NO and cGMP in their occurrence. The enhancement of agmatine myorelaxation by moxonidine pleads for the stimulation of imidazoline receptors.

Within the complex mechanism of hepatic encephalopathy resulting from alcohol poisoning, a significant pathogenic role seems to relate to lipid peroxides (free radicals generated by chronic alcohol poisoning itself). Oxidative aggression is emphasized by the diminishing antioxidative capacity of the body resulting from serious liver injury brought about by chronic ethyl poisoning. The poisoning influences the whole functional capacity of the liver, hepatic protein synthesis included, which also means ceruloplasmin and siderophilin synthesis; the two latter elements make up AOS Cp-Tr which neutralizes the harmful activity of Cu and Fe excess and stimulates release of free radicals of oxygen. The purpose of our research was to study the redox balance alteration in blood in a group of patients who were in a critical condition and had been admitted to the somatic patients ward of the "Prof. Dr. Alexandru Obregia" Neurology and Psychiatry Hospital and who were suffering from hepatic encephalopathy resulting from ethyl poisoning.

The study focused on the effects of intracerebroventricular (i.c.v.) administration of adenosine (10(-7)-10(-5) M) on water metabolism and some electrolytes in adults rats. The i.c.v. administered adenosine decreases both spontaneous and angiotensin II (Ang II) induced ingestion of sodium chloride solution (9/1000). Urinary release was differently influenced. Thus, while the released urinary volume increased in the first 4 hours after adenosine injection, it was not significantly modified on successive administration of adenosine and Ang II. Adenosine decreases the urinary releases of Na+ and K+ and dramatically reduces only Ang II-induced natriuresis. Finally, we can conclude that neural chains involved in the control of uptake and release of water and some ions, include neurons and/or purinergic interneurons.

Pre- and post-pubertal Wistar rats were injected i.m. with a single dose equivalent to 1 UI of Calcitonin (Calsyn-50 Rorer, Swiss). Its effects upon the thymus and adrenals were assessed after 1, 3 and respectively, 8 days since injection. The results pointed to differences of reaction of the thymus and adrenals dependent on rat ages and on the period of hormone persistence in the organism. The effects in mature rats are characterized by a stress state, reflected in adrenal reaction, but without impact upon the thymus in point of biochemical parameters. In rats of that age, modifications in both organs are much reduced after 8 days since calcitonin injection. In pubertal rats, adrenal activity is temperate, and thymus registers modification of DNA, of oxygen consumption and of nitrogen aminic after 3 days since injection. This modification is maintained for 8 days.

Administration of L-thyroxin in a dose of 30 micrograms/chicken, i.m. and 2-thiouracyl in a dose of 0.3 mg/chicken, i.m. for an interval of 3 days, determined, at the thymus level, increases of total protein content in the Tu group, in parallel with decreases of the nitrogen of free amino acids level in the Tx group, increases of DNA content in the Tx group and an increase of the thymus weight in both groups. Modifications are due to the action of thyroxin, on the one hand, and on the other to the doses of antithyroid drug which determines a raise of T4 content in the plasma and the manifestation of activities specific to this hormone.

Ten Sprague-Dawley male rats were sensitised with ovalbumin. The effect of hydrogen peroxide on the constrictor effect of acetylcholine was studied in the isolated tracheal muscle. Preincubation with hydrogen peroxide (H2O2) 10(-3) M (1 min/30 min) does not modify the acetylcholine constrictor effect in the control group. Ovalbumin sensitisation enhanced the acetylcholine constrictor effect (mean value of 19%) irrespective of dosage, comparatively with the control group. Short- and long-term preincubation with hydrogen peroxide enhanced the acetylcholine effect in the sensitised group, irrespective of dosage, comparatively with the control group. A relationship between dosage, contractile response and time of incubation was noticed only in the sensitised group.

This research concentrated on the hydroelectrolytic balance response after centrifugation (+5G/30 minutes, five times) in two lots of rats: one lot made up of animals with normal cerebral excitability, and another one of animals prone to audiogenic seizure. Both before and after centrifugation, we determined: water (ml/24 hrs.) and sodium chloride (mEq/24 hrs.) consumption; dependence of sodium, potassium and water elimination on the amount of sodium ingested (mEq/24 hrs.). We also determined the renal capacity of sodium concentration and the mineral-corticoid response based on the urine Na/K ratio and on the determination of plasma renin activity (PRA). Data obtained show that audiogenic seizure-prone rats consume less sodium and water after centrifugation, unlike normoexcitable rats in which there have been no differences in this respect. Exposure to hypergravitation induces in both lots an increase of sodium, potassium and water elimination. Renal elimination of water is greater in the normoexcitable animals than in the seizure-prone ones. By contrast, sodium elimination is greater in the audiogenic seizure-prone animals. Urine sodium concentration is lower in the seizure-prone animals, consistent with the amounts of water eliminated. Their mineral-corticoid response is intensely diminished after centrifugation in comparison to that of the control, normo-excitable animals. PRA is diminished in both lots. Our findings support the assumption that seizure-prone rats are unable to adaptatively respond to acceleration by preserving sodium through the intervention of cortico-surrenal mechanisms. As water is not preserved, it seems that in this category of animals, both during and after centrifugation, it is mostly the hypothalamo-retrohypophyseal mechanisms that come into play. This could be the outcome of disturbances occurring in the mechanisms of blood sodium transport that are deficient in the seizure-prone animals.

In order to study the influence of lithium on the cellular environment, we conducted research in multiple experimental models: groups of rats with normal cerebral excitability and groups susceptible to audiogenic convulsion, rat neuroglia cultures and perfusion of dog isolated head. We assumed blood composition to be a good indicator of cell environment composition. Blood serotonin level differs in the two groups of animals. Lithium induces a decrease of blood serotonin and an increase of amine concentration in some of the cerebral regions of rats susceptible to audiogenic convulsions. Inverse effects occur in rats with normal cerebral excitability. In the perfused, isolated head of a dog, lithium immediately decreases blood serotonin level. Na and water have a diminished metabolization during the first 24 hrs. in both animal groups. Decrease in metabolization is somewhat greater in hyperexcitable animals. Within 48 hrs. after lithium injection, there is an increase of Na metabolization, probably determined by its storage in the interstice. Renal elimination of K decreases under the influence of lithium 48 hrs. after administering one dose of lithium. Lithium induces, immediately after injection, a decrease of blood Na concentration in the efferent flow of the jugular vein of a perfused dog head. When used in cell cultures, lithium (2 mM concentration) stimulates glial cells division (astrocytes, oligodendrocytes), increases their growth and aging rates. The effects of lithium may be due to its toxicity. Therefore, lithium alters the composition of the cellular environment depending on dose and on the state of the body.

In order to evaluate the effect of the acute viral hepatitis on arterial blood flow we performed duplex Doppler US on 30 patients with acute viral hepatitis (AVH) and compared the results with those obtained on 20 normal volunteers. Hepatic artery flow (HAF) was significantly increased with the patients suffering from acute viral hepatitis. The data obtained show that the increase of arterial blood flow is not always associated with the increase of arterial velocities. We could put in evidence the presence of the hepatic artery response to altered portal blood flow (arterial buffer) during a AVH. If the increase of HAF is absolutely necessary for recovery from hepatitis, excessive increase of HAF seems to increase the time of recovery. In our study, the evolution of acute viral hepatitis was good when the HAF values did not exceed 65% of liver supply. The increase of arterial blood flow over 65% seems to limit the portal supply of the liver and in this way the amounts of regenerating substances which bathe the liver cells. The HAF value plays an important role in acute viral hepatitis evolution, so that the exploration of HAF and hepatic artery velocities may be a reliable examination in order to monitor the evolution of this disease.