Dynamics of the direction of static connections in the electrical activity of the cerebral cortex in the cat

Data have been obtained on three cats for analysis of statistic connections of electrical activity in the visual, parietal and somatosensory cortical zones during development of evoked potentials to photic signal in these areas, and also in periods previous to photic stimulation and on traces of its action. An increase in shown of the influence of activity in the visual area on that of the somatosensory zone in post-stimulus periods and a sharp increase of two-way connections between these areas against the background of a relative equilibrium of direct and backward connections in trace periods.     

Mechanism of strengthening of the contractile activity in the duodenum and in the jejunum in psychogenic stress in rabbits

In experiments on unanaesthetized rabbits myoelectric activity (contractile activity index) of proximal (postpyloric) and distal sites of duodenum, and proximal part of jejunum was studied under stress induced by fastening a rabbit to a table in supine position. In both sites of duodenum, the stress impact induced a short-time decrease of contractile activity which was followed by its increase that exceeded the initial level. In the proximal part ofjejunum, the increase of contractile activity took place only during the second part of stress response. The strengthening of the contractile activity of the proximal part of duodenum was preserved after muscarinic or nicotinic cholinoceptor blockage, and after beta-receptor blockage. It was concluded that the contractile response of the proximal part of duodenum did not result from the contribution of central or local neurogenic mechanism, including excitatory cholinergic one, but was humoral in origin. The strengthening of the contractile activity of the distal part of duodenum and proximal part ofjejunum was abolished by muscarinic cholinoceptor and beta-receptor blockage, and resulted from the action of circulating catecholamines on the excitatory beta-adrenoceptor, localized on the cholinergic neurones of the enteric nervous system.     

Potentiation of the gastro-protective effect of sulglicotide in the presence of cimetidine in the rat

The effects of sulglicotide, alone or combined with cimetidine, have been investigated on mucosal lesions induced in rats by pylorus ligation. In the same animals, the measurement of acid and pepsin output and of soluble and barrier mucus has been performed. Dose-dependent sulglicotide prevented the development of mucosal lesions and its protective effect was achieved without significant modifications in gastric acid secretion. The secretion of pepsin and of mucus was markedly inhibited at every dosage of the compound. Neither the damage to gastric mucosa nor the secretion of acid, pepsin and mucus were affected by cimetidine. The combination of the highest doses of both compounds resulted in a synergistic gastro-protective effect, not dependent on a synergistic effect on the reduction in acid secretion.     

Examination of the role of follicle stimulating hormone in estrogen biosynthesis in vivo and in vitro in the ovary of the cyclic hamster

The effect of neutralizing endogenous follicle stimulating hormone (FSH) or luteinizing hormone (LH) with specific antisera on the in vivo and in vitro synthesis of estrogen in the ovary of cycling hamster was studied. Neutralization of FSH or LH on proestrus resulted in a reduction in the estradiol concentration of the ovary on diestrus-2 and next proestrus, suggesting an impairment in follicular development. Injection of FSH antiserum at 0900 h of diestrus-2 significantly reduced the ovarian estradiol concentration within 6--7 h. Further, these ovaries on incubation with testosterone (T) in vitro at 1600 h of the same day or the next day synthesized significantly lower amounts of estradiol, compared to corresponding control ovaries. Although testosterone itself, in the absence of endogenous FSH, could stimulate estrogen synthesis to some extent, FSH had to be supplemented with T to restore estrogen synthesis to the level seen in control ovaries incubated with T. Lack of FSH thus appeared to affect the aromatization step in the estrogen biosynthetic pathway in the ovary of hamster on diestrus-2. In contrast to this, FSH antiserum given on the morning of proestrus had no effect on the in vivo and in vitro synthesis of estrogen, when examined 6--7 h later. The results suggest that there could be a difference in the need for FSH at different times of the cycle. Neutralization of LH either on diestrus-2 or proestrus resulted in a drastic reduction in estradiol concentration of the ovary. This block was at the level of androgen synthesis, since supplementing testerone alone in vitro could stimulate estrogen synthesis to a more or less similar extent as in the ovaries of control hamsters.     

Role of the mitochondrion in the regulation of protein synthesis in the eucaryote Saccharomyces cerevisiae

Summary Induction of several enzymes is abolished in respiratory deficient strains of Saccharomyces cerevisiae. Such block depends on the integrity of the mitochondrial protein sinthesizing machinery. A model is proposed which is based on a double control of protein synthesis, a negative regulation similar to that described in E. coli and a positive regulation mediated by mitochondria.     

Role of dominant motivation in organizing the functions of the higher divisions of the auditory analyzer in the cat

In chronic experiments on cats, reorganization of initial interrelations between alpha-activity of higher parts of the auditory analyzer during acoustic stimulation was of a selective character and depended on motivational properties of the elicited excitation. A conditioned acoustic signal of alimentary situation, greatly intensified the functional conjugation of the majority of studied auditory projections and a number of non-specific structures, while in a defence situation there was a considerable reduction of correlative dependence between compared characteristics of the auditory centers state and a change in the hierarchy of their functional interrelations.     

Regulation of the total functional state of the brain in dogs in the presence of the 1st and repeated increases in total illumination

The influence of the first and repeated increases of total illumination of the experimental chamber on conditioned activity was studied in chronic experiments on six dogs by the secretory alimentary conditioned reflex method. It was found that such repeated functional loads exert a training effect on the mechanism regulating the general functional state of the brain. In preliminarily trained animals different components of the conditioned reflex are rapidly and synchronously reorganized. In non-trained animals the reorganization of the brain general functional state was prolonged and accompanied by development of a pronounced emotional stress. It has been assumed that training of the functions controlling the general functional state of the brain is based on conditioned mechanisms. An important part is played by the mechanism of conditioned inhibition, which prevents a prolonged retention and reproduction of an excessively intensive level of emotional stress.     

Role of the nongravid part of the uterus in the luteolytic effects of estrogen in pregnant rats

Effects of a low dose of estradiol on the luteal function were studied in intact pregnant rats. The pregnant rats received daily sc injections of 0.1 microgram estradiol or sesame oil from day 7 to 14 of pregnancy (day 1 = day of insemination). Serum progesterone levels on day 15 were significantly lower in the estrogen-treated group than in the oil-treated group. In order to study how estrogen induced luteolysis, the pregnant rats received each of the following treatments on day 7 of pregnancy: (1) The uterus except that containing a single conceptus was removed by hysterectomy (hysterectomy group); (2) All but a single conceptus were removed by aspiration, so that rats carried only a single conceptus with the whole part of the nongravid uterus (aspiration group). Each group of rats received also sc injections of 0.1 microgram estradiol or sesame oil from day 7 to 14 of pregnancy. Estradiol treatment caused a significant decline in serum progesterone levels in the aspiration group on day 15, but this was not the case in the hysterectomy group. There was no significant difference in serum LH levels among any of the groups on day 15 of pregnancy. These results indicated that estradiol induced luteolysis in the intact pregnant rats, which would, at least in part, be mediated through the uterus.     

Participation of the estradiol receptor in the hormonal inhibition of cyclic nucleotide phosphodiesterase in the uterus

The role of estradiol receptor was studied in the inhibitory effect of hormone on the cyclic nucleotide phosphodiesterase from immature Wistar rat uterus. It was shown that the preparative separation of the enzyme and hormone receptor by ultracentrifugation in isokinetic sucrose density gradient results in a 2.5-3-fold decrease of the estradiol effect on phosphodiesterase. This effect is completely restored after adding the separated estradiol receptor to the phosphodiesterase devoid of it. The effect of estradiol on the phosphodiesterase activity depends on a degree of receptor component aggregation: the action of estradiol on the enzyme intensities after transformation of receptor into the dissociated form (4S) and removes in the presence of the receptor component associated form (8S).     

Seasonal changes in the adrenergic fibers in the wall of the microvessels of the cheek pouch of the hamster, Mesocricetus auratus

Adrenergic innervation has been investigated by fluorescent histochemical method with glyoxylic acid. Adrenergic fibers were found in summer period on the arterioles with a diameter varying from 100 to 30 micron, their fluorescence being significantly lower than that in the vessels of microcirculatory bed of the mesentery, tongue, femoral muscles of the same animal. No adrenergic fibers were revealed on the arterioles with a smaller diameter, on veins and venules. In winter period, fluorescence is completely absent from all the vessels of the cheek pouch, which may be due to the decrease in the level of catecholamines in the nerves and other tissues during hibernation.     

Dependence of the anticipatory change in the grip force in the catching task on the result of the preceding trial

A sitting subject held a cup between the thumb and the index finger. Light or heavy objects fell into the cup in a random order. The anticipatory grip force at the moment when the falling object touched the bottom of the cup was measured. The grip force in the trials following the fall of a light object was smaller than in the trials following the fall of a heavy object and did not depend on the object mass in the current trial. Thus, the anticipatory increase in the grip force was planned on the basis of the result of the preceding trial.     

Cranial cartilages: Players in the evolution of the cranium during evolution of the chordates in general and of the vertebrates in particular

The present contribution is chiefly a review, augmented by some new results on amphioxus and lamprey anatomy, that draws on paleontological and developmental data to suggest a scenario for cranial cartilage evolution in the phylum chordata. Consideration is given to the cartilage-related tissues of invertebrate chordates (amphioxus and some fossil groups like vetulicolians) as well as in the two major divisions of the subphylum Vertebrata (namely, agnathans, and gnathostomes). In the invertebrate chordates, which can be considered plausible proxy ancestors of the vertebrates, only a viscerocranium is present, whereas a neurocranium is absent. For this situation, we examine how cartilage-related tissues of this head region prefigure the cellular cartilage types in the vertebrates. We then focus on the vertebrate neurocranium, where cyclostomes evidently lack neural-crest derived trabecular cartilage (although this point needs to be established more firmly). In the more complex gnathostome, several neural-crest derived cartilage types are present: namely, the trabecular cartilages of the prechordal region and the parachordal cartilage the chordal region. In sum, we present an evolutionary framework for cranial cartilage evolution in chordates and suggest aspects of the subject that should profit from additional study.     

Effect of high bromide levels in the organism on the biological half-life of iodine in the rat

In experiments on rats, a significant influence of an extraordinarily high bromide intake on the whole-body biological half-life of iodine was established. Very high bromide intake (1) decreased the amount of radioiodide accumulated in the thyroid, (2) changed the proportion between the amount of iodine retained in the thyroid and the total amount of absorbed iodine, (3) significantly shortened the biological half-life of iodine in the thyroid from approximately 101 h to 33 h in animals maintained on an iodine-sufficient diet and from 92 h to about 30 h in rats fed a low-iodine diet, and (4) changed the time-course (added a further phase) of iodine elimination from the body. These changes were caused, with high probability, by an increase of iodine elimination by kidneys due to an excess of bromide. The overall picture of iodine elimination in animals fed the low-iodine diet was similar to that in animals maintained on iodine-sufficient diet. Presented in part at the 20th Workshop on Macro and Trace Elements held in Jena (Germany) on December 1–2, 2000.     

Positive residues involved in the voltage-gating of the mitochondrial porin-channel are localized in the external moiety of the pore.

The role of positive charges located on the hydrophilic surface of the mitochondrial outer membrane channel was investigated by studying the interaction between LDAO-solubilized porin and a cation-exchanger column. The binding of porin to the column material was inhibited when the elution buffer had a pH of 9 or when 2 mM dextran sulfate was added to the buffer at neutral pH. Interestingly, the addition of a synthetic copolymer of methacrylate, maleate and styrene known as a potent modulator of the voltage-dependence, did not influence the interaction between column material and porin. Incubation of porin with fluorescein isothiocyanate (FITC) resulted in the isolation of a porin fraction in which on average two lysines located on the surface of the pore-forming complex per 35 kDa polypeptide were modified. The voltage-dependence of the fluorescein isothiocyanate modified porin was strongly decreased as compared with the unmodified porin. The experiments presented here give the first biochemical evidence that positively charged lysine residues located on the surface of the channel-forming complex are responsible for the gating of the mitochondrial porin-channel.     

Psychological Attributes of the Culture of the Ukrainians in the Modern Stage of the Development of Society and Trends in Changes in These Attributes in the Post-Soviet Period

The authors of the article focus on the transition of the former Soviet state of Ukraine to a market economy. One aspect of the analysis is the cultural values and attitudes of the citizens in a new situation. Market economy and entrepreneurship demand new types of motivation and individual values from people. A challenge for social psychology in the country is the further elaboration of methodological basis of research.     

Assessing protein co-evolution in the context of the tree of life assists in the prediction of the interactome

The identification of the whole set of protein interactions taking place in an organism is one of the main tasks in genomics, proteomics and systems biology. One of the computational techniques used by many investigators for studying and predicting protein interactions is the comparison of evolutionary histories (phylogenetic trees), under the hypothesis that interacting proteins would be subject to a similar evolutionary pressure resulting in a similar topology of the corresponding trees. Here, we present a new approach to predict protein interactions from phylogenetic trees, which incorporates information on the overall evolutionary histories of the species (i.e. the canonical "tree of life") in order to correct by the expected background similarity due to the underlying speciation events. We test the new approach in the largest set of annotated interacting proteins for Escherichia coli. This assessment of co-evolution in the context of the tree of life leads to a highly significant improvement (P(N) by sign test approximately 10E-6) in predicting interaction partners with respect to the previous technique, which does not incorporate information on the overall speciation tree. For half of the proteins we found a real interactor among the 6.4% top scores, compared with the 16.5% by the previous method. We applied the new method to the whole E.coli proteome and propose functions for some hypothetical proteins based on their predicted interactors. The new approach allows us also to detect non-canonical evolutionary events, in particular horizontal gene transfers. We also show that taking into account these non-canonical evolutionary events when assessing the similarity between evolutionary trees improves the performance of the method predicting interactions.     

The functional role of the pedunculopontine nucleus in the regulation of the electrical activity of entopeduncular neurons in the rat

The purpose of this study was to investigate the influence of the pedunculopontine nucleus (PPN) on the electrical activity of entopeduncular nucleus (EP) in the rat and to analyze the influence of the subthalamic nucleus (STN) on the PPN-evoked responses of EP cells. Most of the EP neurons recorded (65.1%) were identified electrophysiologically as output cells projecting to the lateral habenula while only a minority (3.8%) were output cells to the PPN. Stimulation of the PPN in intact rats caused a short-latency (2.5 +/- 2.0, S.D. ms) activation in 22.6% and suppression of activity in 8.5% of EP neurons recorded. The mean impulse rate of EP neurons in intact rats was 27.0 +/- 5.5, S.D. imp./s and the overall mean interspike interval 36.8 +/- 7.1, S.D. ms. In rats where the PPN had been destroyed 10-12 days before recording by a local microinjection of kainic acid only a few EP neurons were still responsive to stimulation of the PPN showing suppression of activity. In these rats the kainate lesion slowed the impulse spontaneous activity to 14.3 +/- 6.3, S.D. imp./s and markedly altered the distribution of interspike intervals in 62.5% of the EP neurons recorded. The overall mean interspike interval in this group of deregulated neurons was 68.2 +/- 20.1, S.D. ms. A small kainate lesion of the STN placed 4-5 days before recording, on the other hand, did not affect the spontaneous activity of EP cells but increased the percentage of cells which were activated (43.6%) by stimulating the PPN. The present data demonstrate a predominant activatory influence of the PPN on EP cells and suggest that destruction of the STN may affect the responsiveness of entopeduncular cells to stimulation of the PPN possibly through the removal of a tonic inhibitory STN influence on the EP.     

Immunohistochemical localization of the transferrin receptor in the seminiferous epithelium of the rat

The transferrin receptor has been immunohistochemically localized in the seminiferous epithelium of the rat with a monoclonal antibody, MRC OX26, which recognizes the transferrin receptor glycoprotein. The receptor was detectable on mitotically and meiotically dividing germ cells and, less abundantly, on round spermatids. It was lost from germ cells during spermatid elongation and was undetectable on immature spermatozoa. The transferrin receptor was also present on Sertoli cells in the testes of immature animals and on Sertoli cells in the testes of aspermatogenic animals that had been irradiated in utero. It was not detectable on Sertoli cells in the testes of cryptorchid animals. These studies demonstrate that the transferrin receptor is abundant on dividing germ cells as well as dividing somatic cells.     

Studies on the involvement of prostaglandins in implantation in the rat

Studies of prostaglandin (PG) production by uterine homogenates of rats in early pseudopregnancy and pregnancy showed that production of 6-oxo-PGF-1 alpha, PGF-2 alpha and PGE-2 peaked on Day 5 of pseudopregnancy whereas only 6-oxo-PGF-1 alpha and PGE-2 peaked on Day 5 of pregnancy, the day of implantation. 6-Oxo-PGF-1 alpha was the major product in both reproductive states. Indomethacin treatment of rats during early pregnancy caused a delay in implantation, a significant reduction in uterine weight, and a much reduced number or absence of implanted blastocysts in the uterus on Day 9. Plasma progesterone levels were also significantly lower in indomethacin-treated, pregnant rats. These findings support roles for prostaglandins in implantation, and in fetal development.     

Features of corticofugal effects of the motor area of the cortex on processing of heterogeneous afferentation in the parafascicular complex of the thalamus in the cat

Evoked potentials to somatic and visual stimuli were recorded in the parafascicular complex (parafascicular nuclei--centrum medianum--Pf--CM) of the thalamus of cats anaesthetized by nembutal. Cooling of the motor cortex was also used. The influence of the motor cortex on processing of the visual and somatic afferent signals at the thalamic level was found to be direct but different by its character. The motor cortex exerted unidirectional facilitatory modulatory action of a tonic type on the processing of visual afferentation and general facilitatory influence against the background of which particular excitatory and inhibitory effects were seen which it exerted on the processing of somatic signals. Episodically the motor cortex completely controlled the afferent inputs activated by somatic impulses. The motor cortical area non-equally influenced afferentation of the same modality forming the different components of the evoked potentials in Pf--CM. On the base of our present and earlier obtained data an idea has been formed of existence of a general principle of differentiated influences of polysensory areas on heterogeneous afferentation on nonspecific and association thalamic nuclei, and of realization of these influences through separation of functionally isolated subsystems in descending pathways. Each of the subsystems by closing separate thalamo-cortical circuits might transmit signals of a single modality.