Ultrastructural Changes in the Penumbra of the Local Cerebral Infarction in Rats.

We studied changes in the ultrastructure of synapses and myelin nerve fibers that develop in the penumbra in 4 and 12 h and 2 and 4 days after modeling infarction in the frontoparietal cortex in rats. Ischemic stroke was induced by injection of a photosensitive dye into their bloodstream followed by illumination of the brain surface with a halogen lamp. Visible ultrastructural changes were observed in the penumbra zone, namely in the axodendritic and axospinous synapses; they consisted in polymorphism and disorganization of synaptic vesicles, mitochondrial swelling, swelling and vacuolization of the postsynaptic fragments of dendrites, and shortening and osmiophilia of the active zone.

RADON HORMESIS IN EPILEPTIC PATHOGENESIS AND PREDICTORS OF OXIDATIVE STRESS.

Numerous experimental and clinical studies have shown that oxidative stress (OS) plays an important role in the development of epilepsy. The epileptic seizures themselves are caused by OS and, under conditions of a hypermetabolic state, cause an intensive production of reactive oxygen species (ROS) in the brain. The reason for this is called a change in the energy balance in the brain.

Some Aspects of Role of Nitric Oxide in the Mechanisms of Hypertension (Experimental Study).

Background: Modulation of endothelial function is a therapeutic option to reduce some of the significant complications of hypertension. However, the relationship between endothelial dysfunction reduced nitric oxide (NO) production, and the development of hypertension is not fully understood. To establish a potential pathogenetic link between impaired NO synthesis and hypertension, we investigated the results of competitive interaction of the substrate of NO synthase, L-arginine, and its analog, an non-selective inhibitor of NO synthase, N-nitro-methyl ether-L-arginine (L-NAME), in experimental rats.

CHANGES IN ARTERIOLE REACTIVITY TO NORADRENALINE UNDER CONDITIONS OF HYPERHOMOCYSTEINEMIA.

The aim of the research was the experimental study of one of the possible mechanisms performing contractile activity of arterioles in hyperhomocysteinemic animals. Moderate hyperhomocysteinemia was induced in male rats (120-160 g., n=12) by adding L-methionine to the drinking water during 4 weeks.

EFFECTS OF HIGH AND LOW DOSES OF ETHANOL, GIVEN TO RATS DURING THE PROCESS OF PREGNANCY, ON THE BEHAVIOR AND THE BLOOD RHEOLOGICAL PROPERTIES OF THEIR OFFSPRINGS.

In our experiments it has been established that during pregnancy the impact of ethanol high dose on rats' offspring induces a well pronounced increase of plasma viscosity, which is extremely important in blood circulation. The disruption of blood circulation causes a hypoxic condition (especially, in nervous tissues) and the disturbance of its functioning. This is the result of what has been seen in the behavioral experiments of female rats' offspring under the influence of ethanol high dose.

[SOME PHYSIOLOGICAL PROCESSES IN ISCHEMIC PENUMBRA OF THE BRAIN (REVIEW)].

The zone of penumbra in ischemic brain tissue lies below the local cerebral blood flow threshold for electrocortical silence but above that for anoxic depolarization and massive ionic dyshomeostasis. Conflicting data concerning the width of therapeutic window in which successful reperfusion of blood still is possible, are cited in this paper. The role of temperature in development of ischemic stroke is also considered.

EFFECT OF FREE RADICALS ON CALCITONIN-GENE-RELATED PEPTIDE MEDIATED VASODILATION.

It is known that in some pathological conditions, due to the formation of a large number of free oxygen radicals, the cardiovascular system is severely affected. However, the effect of free radicals on CGRP-mediated vasodilation remains unclear. The aim of this work was to study the effect of free radicals on CGRP-mediated neurogenic vasodilation on preparations of an isolated rabbit lingual artery.

[Possible mechanism of hyperemia in the skin caused by non-painful mechanical pressure].

It is believed that hyperemia in the skin, resulting from applied weak mechanical pressure delays the development of ischemia, and that it is a defensive neurovascular reaction against the local pressure, which can be considered as a critical point in terms of prevention of ischemia and, respectively, the risk for development of bedsores. Taking into account that nitric oxide can be released from autonomic nerves and make a significant contribution to the functioning of the mechanism of neurogenic vasodilation in different tissues, and the fact that the same role can also play the calcitonin gene-related peptide, the aim of this study was to clarify the role of each of these factors in the development of local hyperemia caused by non-painful, mechanical pressure on the skin. In experiments on white rats with a quantitative measurement of the intensity of skin blood flow, it was confirmed that in case of non-painful pressure acting on the skin, two-phase reaction of local blood flow appears - at first there is an increase in its level, and then an exponential decrease with stabilization at a level below the initial one.

Neuroprotective treatment of cerebral infarction: an experimental study.

We investigated the effect of the amniotic-derived peptide Plaferon-LB on cerebral tissue damage during photochemical insults in rats. Plaferon-LB (US patent number: 20070123467 A1) was extracted from the amniochorionic membrane of a human placenta and showed a relatively strong antihypoxic effect compared to other interferon. Thrombotic infarction was induced by photochemical illumination after intravenous injection of Rose Bengal.

[Iodine deficiency in the prenatal period may form learning ability deficiency in the postnatal period].

The present study analysis the changes in learning ability of the progeny of rats suffered from iodine deficiency. Reduction of serum thyroxin in the mothers' blood during three months before mating and whole period of gestation to an average level of 4,7+/-0,6 ng/ml, significantly worsened the learning ability in progeny, and the reduction to 1,1+/-0,4 ng/ml - completely deprived progeny's learning ability. Passage of the maze for these animals was purely probabilistic in nature without any signs of learning We can conclude that the diet with very low iodine content results in a low level of thyroxin in maternal serum and neurological deficiency in progeny manifested by learning disability during maze testing.

Hyperthermia-induced morphological changes in cerebral tissue of the rat.

The sensitivity of cerebral tissue to hyperthermia, its immediate effect, manifested by histological changes and the role of local blood flow, blood rheological properties, and the possible role of free radicals in development of mentioned changes have been studied. Through the cranial window local area of cerebral surface was irrigated by artificial CSF heated up to 41, 43 or 45 degrees C. Serial brain coronal sections 50 microm thick were analyzed under light microscope.

[Regulatory mechanims of smooth muscles contractility in the cerebral arteries].

The results obtained in the experiments on large cerebral arteries are summarized in the presented article. It was declared that direct application of these data to the properties and peculiarities of contractile activity having place in smooth muscles of the small arteries is not fully admissible, because these vessels have different spatial organization and rheological properties. More over, in accordance with the functional heterogeneity conception, such an application is not generally acceptable even from the theoretical point of view.

Changes in tumor tissue oxygenation during microwave hyperthermia: clinical relevance.

As previously described (Bicher 1981) TpO2 and blood flow increase in tumor as temperature increases until 41 degrees C and decrease thereafter (microcirculation "breaking point"). In the present clinical study using O2 microelectrodes this response was reproduced in over 54 treatment sessions. However, it was found that as treatment progresses (patients are treated for one hour 10 times, twice weekly, and concomitantly receive 4000 rads of ionizing radiation) the initial increase of blood flow and TpO2 is reduced and there is immediate decrease in tissue oxygenation.