Acta biologica Academiae Scientiarum Hungaricae最新文献

Late effect of the perinatal administration of oestradiol dipropionate on pituitary gonadotrophs and the morphology of the LH-RH neuronal system was tested both in male and female rats. Oestrogen caused a severe reduction in the number and size of immunodetectable gonadotrophs in both sexes. By the 90th day of life, however, immunomorphology and distribution of the gonadotroph cells had became normal, and also the LH-RH system of the animals was similar to that of the intact controls. The lack of vaginal cycles indicated, however, that oestrogen might have permanently impaired higher brain centers regulating cyclic gonadotroph hormone release.

The paper presents morphological evidence that upon deafferentation small Golgi cells and granule cells of the cerebellar cortex as well as geniculo-cortical relay cells of the Lateral Geniculate Nucleus develop presynaptic sites on their otherwise exclusively postsynaptic dendrites. The new synapses are, therefore, mostly dendro-dendritic, a logical consequence of the fact that in the absence of axonal sprouting in the two regions, the reactive synaptogenesis in the cerebellar cortex and LGN is accomplished by the participation of the (newly formed) presynaptic dendrites.

Nuclear protein phosphatase (phosphoprotein phosphohydrolase, EC. 3.1.3.16, abbreviated: NPPase) was extracted from rat liver cell nuclei and subnuclear fractions under different conditions. NPPase activity proved to be strongly bound to chromatin and its presence cannot be explained by an incomplete removal of the cytoplasm from nuclear preparations. The small extent of activation of NPPase after treatment with ethanol or mercaptoethanol suggests that NPPase is present in the nucleus in its activated form. On the other hand, cytoplasmic protein phosphatase (abbreviated: NPPase) from rat liver also showed only a small extent of activation after precipitation with ammonium sulphate or ethanol. Therefore, the pronounced activation of cytoplasmic PPase, which has been observed in rabbit liver and skeletal muscle, cannot be used for differentiation between cytoplasmic and nuclear PPases in rat liver.

A coulometric model system is described which facilitates the quantitative study of the kinetics of transformation of amorphous calcium phosphate (ACP) into calcium-hydroxy-apatite (CHA) crystals. Proteoglycans of high molecular weight and over-sulphated polysaccharides (Arteparon, dextran sulphate) delayed CHA crystal formation. The results have enabled us to characterize the structure activity relationship of inhibitors of CHA formation, and to postulate a general structural requirement for molecules with inhibitory effect. As working mechanism, binding of calcium ions by sulphate groups of polyanions was supposed, which might reversibly impair "the critical nuclei formation", and/or further deposition of calcium ions in the CHA crystals. The clinical, therapeutical significance of the determination of the threshold concentration of different compounds is discussed.

In rabbits, the right hind limb was immobilized by means of plaster cast for 1, 2, 4 or 6 weeks and the activities of some metabolic enzymes: GOT, GPT, LDH, aldolase and acid phosphatase (in part of lysosomal origin), were examined in the slow m. soleus, and in the fast m. gastrocnemius. The former muscle is known to have mainly an oxidative, while the latter mainly a glycolytic type of metabolism. The activities of enzymes highly involved in the metabolism of the muscle diminished for a certain time during atrophy, then a relative rise occurred. Acid phosphatase activity likewise decreased after an initial relative increase. Reduction of enzymatic activities is explained by the activation of proteolytic enzymes, on the basis of measurements performed in these experiments and of results published by others. The decrease of enzymatic activity was more marked in the muscle which in normal state exhibits higher activity than in the other type of muscle studied. Thus, in the gastrocnemius a high rate of degradation of glycolytic enzymes was observed, while in the soleus degradation of oxidative enzymes prevailed. This phenomenon leads to the dedifferentiation of the muscle cell during immobilization.

The Golgi method more than hundred years old can reveal new results also in the current research of CNS. The study provides examples for using the Golgi method and demonstrates the types of neurons, the various types of interneurons, characterizes the stellate cells in layer IV of the cortex. The Golgi method is applicable for the observation of maturation process and also for demonstrating different pathological alterations of neurons in the CNS.

Studies on fluorescent histochemical localization of monoamines in strips of connective tissue teared off the electric organ of Torpedo marmorata revealed an extensive system of yellow fluorescent nerve fibres. No green fluorescent (catecholamine-containing) axons were found in this region. The significance of the presence of indole-containing axons in the connective tissue of the electric organ is in accordance with previous findings on a high level of serotonin in the Torpedo electric organ and contradicts the general assumption that the electric tissue is a source of purely cholinergic nerve endings.

An account of the origin of the term liaison brain leads on to an historical account of its usage, particularly in voluntary movement. Empirical evidence was provided by the readiness potential of Kornhuber and associates, which even indicated a key role for the supplementary motor area, SMA. It was found by Brinkman and Porter that in voluntary movement many neurones of the SMA were activated probably up to 200 msec before the pyramidal tract discharge. Then came the (133)Xe investigations of regional cerebral blood flow by Roland and associates to reveal that there was neuronal activity in the SMA of both sides during a continued series of voluntary movements, and that his even occurred when the movement was being thought of but not executed. The microstructure and connectivities of the SMAS are considered in relationship to its proposed key role in being excited by the mental act of intention and then calling up the appropriate motor programs to give the desired movement: each mental intention would act on the SMA in a specific manner; the SMA has an 'inventory' and the 'addresses' of stored subroutines of all learnt motor programs and so is able to institute the desired movement by its neuronal connectivites. In conclusion there is a general account of the concept of the liaison brain both for intention and perception.