A possible correlation between unscheduled DNA repair and cholesterolemia in Wistar rat, modulated by vitamin E.

Cholesterol plays a critical role not only in modulating membrane structure and dynamics but also in its metabolic pathway, to interfere with cell growth and proliferation processes. Having this aim in mind, we have suggested an investigation, by radioisotopic techniques, of the effect of vitamin E (alpha-tocopherol, 3 mg/kg b.w. in daily doses, for 7 days) on the unscheduled DNA biosynthesis, induced by Romanian cytostatic Lomustin (Nipalkin or CCNU at the dose of 10 mg/kg b.w in acute administration, for 24 h), both on normally fed animals and on rats having a hypercholesterolemic diet, for 30 days. Considering the scientific data from the literature, according to which there is an inverse correlation between the serum cholesterol level and the risk of developing cancer, we tried to investigate the possible influence of Wistar rat cholesterolemic background on the nuclear unscheduled DNA biosynthesis, essential for the conservation of the cell genome integrity. So, it has been noticed that: 1) the DNA lesions induced by the alkylant and tested by the uptake of 3H-Thymidine (200 microCi/100 g b.w.) are reduced after vitamin E treatment, suggesting a protective effect of the antioxidant on the genetic material. 2) on a hypercholesterolemic background the administration of Lomustin produces a decrease of cholesterolemia, suggesting the development of a "facilitating environment" for CCNU action, which appears to confirm the data from the biographical sources. 3) using 3H-Cholesterol (150 microCi/100 g b.w.) to estimate its intracellular liver incorporation suggests a possible displacement of cholesterol from the tissue compartment to the serum one and reverse, event which appears to be correlated with unscheduled DNA biosynthesis. This sustains the idea of the intracellular cholesterol necessity during the nucleic acid biosynthesis as well as in genome aggression.

Spin-spin relaxation times in myocardial hypertrophy induced by endocrine agents in rat.

Magnetic resonance techniques afford a significant advantage for noninvasive diagnosis of cardiovascular pathology. The purpose of our present study was to assay the proton nuclear magnetic resonance (1H-NMR) sensitivity in the differential diagnosis of certain endocrine cardiovascular complications. In this context, we investigated the water state and content in the hypertrophied myocardium. Male and female Wistar rats were treated with different hormones (hydrocortisone acetate, testosterone, estradiol, thyroid hormones) in combination with isoproterenol (a synthetic catecholamine that induces myocardial ischemia and hypertrophy). The animals were sacrificed after 20 days of treatment and samples of integral myocardium and left ventricular myocardium were analyzed on a 1H-NMR AREMI spectrometer (0.6 T; proton resonance at 25 MHz). The estimation of T2 was made by Carr Purcell-Meiboom-Gill pulse sequence. The data were fitted to a bi-exponential curve, yielding short (T21) values for bound water and long (T22) values for free water. In order to evaluate the myocardial hypertrophy, the following ratios were calculated: integral myocardium to body weight; left ventricle to body weight; left ventricle to integral myocardium. The first two ratios were also calculated for dried tissue, in order to estimate its contribution to myocardial hypertrophy. Our findings demonstrate that myocardial hypertrophy is associated with a decrease of T22, as a consequence of the increase in the dried component (i.e. proteins) of the tissue, while the total tissue water (H2Ot%), measured by gravimetry) was not significantly modified. Nevertheless, it is reasonable that the increase in the protein content would be proportional with the increase in H2Ot%. The decrease of T21 seems to be proportional with the level of left ventricle hypertrophy in female groups. The 1H-NMR measurements were much sensitive for the differential diagnosis of myocardial hypertrophy in the case of left ventricle.

Chemical carcinogenesis as a factor altering the tissue ability to bind hormones. Benzo(a)pyrene--insulin interrelationship.

The present study was carried out on the uptake of 125I-insulin in the tissues or organs (liver, subcutaneous adipose tissue, striated muscle, renal cortex, frontal lobes of the brain) of normal Wistar rats or from animals treated with benzo(a)pyrene, a powerful carcinogen which s metabolically activated in the liver. The carcinogen was administered as follows: (a) in adult life by a single injected dose; (b) in early fetal life by administration to pregnant females and (c) in late fetal life, likewise by administration to the mothers. The results of combined administrations were studied as well. The ability of normal tissues to take up insulin was determined. The administration of a single benzo(a)pyrene dose produced marked alterations in binding of the hormone in some of the tissues, which might be attributed to certain general changes in the properties of the cell membranes. It has to be underlined that after the contact with the carcinogen in fetal life, the tissular ability to take up insulin is irreversibly and non-uniformly altered. This ability is easily influenced by a new carcinogenic dose.

Proofs concerning the existence, in the blood of hypertensive patients, of some serum factors influencing the vascular smooth muscle and the myocardium physiology.

Starting from the existence of some autoimmune diseases (i.e. bronchial asthma or miastenia gravis) we asked ourselves if some plasmatic factors do exist, influencing the receptor--mediator relations in cardiovascular system during some illnesses having unknown etiology, as arterial hypertension. For this reason, in this work was tested the hypothesis that, in some chronic cardiovascular diseases would exist factors circulating and affecting the functions of the cellular membranes of the arterial wall, particularly of the smooth muscle cells and myocardial cells. Our results show a significant modification of the calcium fluxes and of some neuromediators uptake at the hypertensive patients.

Influence of sex and glucocorticoid hormones on 3H cholesterol uptake in the aortic wall and 3H adrenaline in the brain.

The mechanisms involved in the atherogenesis process and the connection of the latter with stress were studied, by trying to elucidate the difference in the response of the two sexes to the causative factors. To this purpose, the role of the sex hormones (testosterone, estradiol, progesterone) and glucocorticoids (hydrocortisone hemisuccinate) in 3H cholesterol uptake in the aortic wall and 3H adrenaline in the brain was investigated. In males, the results show that these hormones favoured the uptake of the two markers whose level was significantly raised (p greater than 0.05; p greater than 0.01) as against the controls all along the 20 days of treatment. In females, the level of 3H cholesterol in the aorta and 3H adrenaline in the brain had a statistical significance (p greater than 0.05) only in the first days of treatment but after the 6th day it began to decline.

Chromatin structure, number, volume and position of nucleoli in rat hepatocyte after treatment with benzo(a)pyrene and N-acetylaminofluorene.

In Wistar rat liver, after the acute treatment with two carcinogenic substances - benzo(a)pyrene and N-acetylaminofluorene - changes involving the nucleus are observed 2, 4 and 6 hours later. The electron-microscopic aspect of the chromatin, as well as the number and volume of nucleoli are altered. The parameters considered (number, mean volume and total nucleolar volume related to nuclear number) showed a movement of the nucleoli inside the nucleus from and towards the nuclear membrane, as a reaction to the chemical oncogenic stress. Thus, there is a relative variation of the number of nucleoli which come into contact with the nuclear envelope or occur within the nucleus. The number and volume are increased 2 hours after the treatment in the case of the nucleoli placed close to the nuclear membrane; the same process is observed after 4-6 hours in nucleoli located centrally. In the experiments described, the reversibility of most of these changes 24 hours after the treatment appears as being the rule.

Deuterium oxide effects upon three parameters characterizing the activity of glycerol-extracted muscle: phosphate release, ATP-induced shortening, and 22Na+ distribution.

ATP splitting activity is progressively reduced with increasing heavy water (D2)) concentration. In contrast, sarcomere shorteining inhibition produced by D2O does not significantly depend on its concentration. Even at low concentration, the presence of D2O does reduce the excessive accumulation of radioactive sodium within glycerinated frog muscle. These heavy water effects on muscular contraction and soidum distribution can be interpreted to indicate adsorbed water within the cells. Evaluation of these experimental results in terms of Gibbs free enthalpy of binding at the adsorption sites of D20 or H20 is in good agreement with the data in the literature.

The gastrointestinal tract in hypokinetic rats.

In Wistar rats kept for 15, 30 and 60 days in a hypokinetic state in special cages, alteration of some gastrointestinal glands was studied by means of histochemical and electron microscopic methods. After 15-30 days of hypokinesia, a decrease was found in the muco-polysaccharide content of the submaxillary, gastric and duodenal glands. The intestinal goblet cells appeared vacuolated. The oxyntic cells, which secrete HCl, as well as the G antral cells, which secrete gastrin, were in an active state. The hypokinetic rats exhibited increased gastric secretion. The electron microscopic aspect of the principal cells corresponded to augmented pepsin secretion. The enterocytes showed an increase in their leucine aminopeptidase, acid phosphatase and glucose-6-phosphatase content. In the submucosa of the fundus of the stomach an accumulation of eosinophils was observed. These modifications were more striking after 15 than after 30 days, and disappeared after 60 days of hypokinesia. These morphological and functional changes may be explained by glucocorticoid hypersecretion corresponding to a stress reaction.

Modifications of ouabain inhibition of xenon accumulation in red blood cells. Implications regarding cell water structuring.

Ouabain is known to depress uptake of xenon by red blood cells, but it is now found that the depressive effects of phenolsulfonphthalein (PSP) or heavy water are even more marked. Ouabain partly reverses those effects in a manner suggesting it exerts a constant action on xenon exchange regardless of the presence or absence of PSP or D2O. Processes analogous to exchange diffusion between certain anesthetic substances and xenon were also observed. The theoretical consequences of the findings are discussed.

Biochemical changes in the rat brain associated with dinitrophenol-induced brain edema.

The present paper was designed to the study of cerebral edema induced by intracarotid infusion of dinitrophenol. The determinations included variations in three lysosomal enzymes (acid phosphatase, cathepsin C and beta-glucuronidase), Na+-K+-ATP-ase, changes in cerebral RNA and protein concentrations and the synthesis of these macromolecules in vitro. In experimental brain edema a drastic drop in the activity of lysosomal enzymes took place. The acid phosphatase decreased to less than 30% of controls. Cathepsin C and beta-glucuronidase were reduced about 30% and 50% of control levels respectively. Protein concentration in the cerebral tissue also decreased by more than 50%. The concentration of RNA, RNA synthesis, and the level of Na+-K+-ATP-ase remained unchanged. Protein synthesis was stimulated by 75% (against controls). All these phenomena were suppressed when the animals subjected to the action of dinitrophenol were concomitantly treated with the antiacidotic substance, tris (hydroxymethyl) aminomethane.

[Study of cellular immunity in rheumatoid arthritis]. / Etude de l'immunité cellulaire dans la polyarthrite rhumatoïde.

The responsiveness to mitogens of the in vitro cultural peripheral blood lymphocytes from 60 patients with rheumatoid arthritis (RA) and from controls was evaluated in terms of H3 TdR uptake. The size of the response was tested for a correlation with the percentages of T and B lymphocytes, determined by E and EAC rosette test, as well as with the various alterations of the clinical and biological parameters. In the RA cultures an elevated level of spontaneous H3 TdR uptake was found, which could be an in vitro carry-over of an activation in vivo. No significant statistical differences were found between rheumatic and control groups as regards: 1 degrees--the H3 TdR uptake induced both by PHA and SLO; 2 degrees--the proportion of the circulating T and B lymphocytes. The only positive correlation evidenced by this study in RA patients was that between the proportion of B lymphocytes and the gammaglobulin level in the plasma.

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.

The effect of +Gz acceleration upon lactate, pyruvate and some nucleotides in the nervous tissue of the guinea pig.

The present paper was designed to the study of the effects of hypoxia induced by positive accelerations upon energy metabolism in the brain. Variations in the amount of lactate, pyruvate, ATP, ADP and AMP were determined immediately after centrifugation and after intervals of 30 to 90 minutes. An increase in the quantity of lactate and pyruvate, and a diminution of ATP running parallel to an increase in AMP were noted immediately after centrifugation. These variations almost entirely disappeared 90 minutes after centrifugation. These findings drew attention to a possible imbalance of the neuronal energy processes, which might bring about, even for short periods, alteration of the neuronal function.

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.