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Biomedical subjects

J Takács

Publications and source records attributed to J Takács.

At least 19 recordsLinked to original sources
PubMed1992

[Experience with using a myocutaneous flap, obtained from the gluteus maximus, in covering sacral decubitus wounds].

Nonsurgical treatment of pressure sores of the sacral region showed in long term poor results. After a short review of surgical procedures the method of gluteus maximus myocutaneous flaps is described. The results suggest that the method offers a well vascularised and resistant soft tissue cover of the pressure sore and it can be performed in any surgical department. Stay in hospital may decrease significantly and the hope for a complete rehabilitation increases.

Buttocks↗
PubMed1992

Effect of dark rearing on the volume of visual cortex (areas 17 and 18) and number of visual cortical cells in young kittens.

The surface area, total volume, and total number of neurons of areas 17 and 18 in one hemisphere of dark-reared (DR), dark-reared and light-exposed (DRL), and normally reared (NR) kittens were studied at the age of 6 weeks. The thickness of the visual cortex was lower by 13% and 11% (area 17) and by 17% and 16% (area 18) in DR and DRL groups, respectively, when compared with similar cortical areas in NR kittens. The surface area values of area 17 were nearly the same in DR and DRL kittens, both being, however, 37% smaller than in NR animals. The surface area of area 18 was significantly smaller than that of area 17 in each group, and was also lower in DR (by 27%) and DRL (by 21%) groups when compared with the NR group. As a consequence of dark rearing, the numerical density of cortical neurons in area 17 amounted to about double of the value observed in normally reared kittens and was also significantly higher in area 18. The numerical density of nerve cells of DRL kittens fell between the DR and NR groups. The total cortical volume of area 17 was similar in DR and DRL groups but it was by 46% (DR) and by 44% (DRL) smaller than in NR kittens. In each experimental group, the total volume of area 18 was significantly smaller than that of area 17. The cortical volume of area 18 was also smaller than in the NR group by 39% and 34% in DR and DRL groups, respectively. In DR and NR kittens, the total numbers of neurons in areas 17 (DR = 26.4 million, NR = 25.7 million) and 18 (DR = 8.5 million, NR = 9.0 million) were essentially similar. In the DRL groups a significantly smaller number of cortical neurons was found both in area 17 (21.5 million) and in area 18 (6.8 million). It is concluded that, in spite of considerable differences in the cortical thickness, surface area, numerical density, and total cortical volume, the absolute numbers of neurons in area 17 and 18 of visually deprived (DR) and NR kittens do not differ at 6 weeks of age. The main deficit in cortical organization following dark rearing, therefore, appears to be confined mainly to the neuropil, as a result of an underdevelopment of neuronal processes and of depressed synaptic organization.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

GABA-containing neuronal processes in normal and cortically deafferented dorsal lateral geniculate nucleus of the cat: an immunogold and quantitative EM study.

The qualitative and quantitative synaptology of flat synaptic vesicle containing "F" type terminals was analysed in normal and in chronically cortically deafferented dorsal Lateral Geniculate Nucleus (dLGN) of the cat using an electron microscopic immunogold technique for visualization of GABA. A direct correlation was found between the density (number of gold particles) of GABA immunostaining and the number of synaptic vesicles in different F terminals. This suggested a quantitative relationship between transmitter content and the number of vesicles in the labeled terminals. Not only the number but also the size of synaptic vesicles was found to be different in the two main groups of F profiles, i.e. the axonal F1 and dendritic F2 terminals. Measurement of the size of synaptic vesicles in F1 axon terminals revealed two subpopulations of these endings: "F11" and "F12" terminals with vesicle diameters of 31.56 +/- 0.08 nm and 33.73 +/- 0.12 nm (P less than 0.01; Chi2 test) respectively. The size of synaptic vesicles in axonal F12 terminals was identical to that found in F2 dendritic profiles, suggesting that both processes belonged to the same, intrageniculate (interneuronal) cell population. F11 terminals, however, appeared to be axonal endings of extrageniculate (most probably of perigeniculate) neurons. Quantitative analysis of the two types of GABAergic axon terminals revealed the geniculocortical relay cells to be the main postsynaptic targets for F11 (extrageniculate) terminals while F12 axons terminated equally on both interneurons and relay cells. Following chronic decortication of the dLGN, the distribution pattern of both GABAergic axonal types had changed considerably. As a result of a severe loss in relay cells, more F11 and F12 axon terminals were found on GABA-containing interneuronal processes than on relay cells. An increase in the number of F1 axonal terminals per neuron was also revealed, (particularly on GABAergic interneurons), suggesting a compensatory reactive synaptogenesis by both F axonal types following decortication.

Afferent Pathways↗
PubMed1991

Number of GABA-immunopositive and GABA-immunonegative neurons in various types of neocortical transplants.

Quantitative investigation of GABA-immunopositive and GABA-immunonegative neurons was performed in grafts of embryonic tissue of somatosensory cortex, (1) injected intraparenchymally into the barrel field of adult rats (n = 5); (2) placed in an acute cavity in the same area (n = 9); or (3) implanted into the anterior eye chamber (n = 5). Analysis of initial embryonic tissue at the age of grafting (E17) demonstrated high numerical density of neurons both GABA-positive and other. Six months after grafting the total neuronal density was higher than in normal cortex in both groups of intracortical grafts, but was lower than normal in the intraocular grafts. The numerical density of GABA-positive somata, however, decreased in all types of the grafts, and their ratio to GABA-negative neurons was significantly lower than in normal neocortical tissue. The total numerical density of the neurons in the grafts had strong positive correlation to the degree of morphological graft/host integration, which was evaluated as a ratio of extent of area of direct graft/host neuropil confluence versus the total extent of the border. The mean diameters of nuclei of GABA-negative cells in both groups of intracortical grafts did not differ from those of the intact neocortex, but in the isolated grafts they were substantially larger. Nuclei and somata of the GABA-positive cells, however, were hypertrophic in all groups of grafts, and especially in the intraocular ones. Measurements of the diameters of host neocortical neurons adjacent to the grafts also exhibited a less marked but still significant hypertrophy. The possible role of various factors (synaptic, trophic, functional), determining the described alterations in neuronal populations within the grafts is discussed.

Animals↗
PubMed1991

Quantitative estimation of the ratio of GABA-immunoreactive cells in neocortical grafts.

Somatosensory anlage from 17-18 day old rat embryos were transplanted in place of the removed barrel cortex in adult rats. Six to eight months after transplantation, the grafts were either completely separated by glial scar or partly separated and partly confluent with the host neocortex. Each was studied histologically and immunostained for GABA. It was found that in partly confluent grafts the neuronal density was similar or even higher than in the host cortex, while the cell number in the separate grafts was much lower than in the nearby host cortex. The number of GABA-positive cells, however, was in all grafts significantly lower (2.9% on average) than in the normal cortex (11.8% on average). The decline in GABA-stained nerve cells was highest in separated grafts, but was somewhat less marked in transplants partly confluent with the host tissue. The possible role of partial or total deafferentation as well as the relative vulnerability of the transplanted tissue by temporary hypoxia and other metabolic disturbances are discussed as the probable factors in selective decline of GABA-ergic cells in the transplanted somatosensory cortex.

Animals↗
PubMed1990

Plasticity of GABA- and glutamate-containing terminals in the mouse thalamic ventrobasal complex deprived of vibrissal afferents: an immunogold-electron microscopic study.

GABA and glutamate immunogold staining demonstrated that nerve cells of the thalamic ventrobasal complex (VB) of mice were positive exclusively for glutamate. None of the neuronal perikarya reacted the GABA antibody. By using alternate thin sections of the normal VB, it was also shown that large "specific" somatosensory and small corticothalamic terminals, both of which contained spherical synaptic vesicles, exhibited only glutamate-like immunoreactivity. A third axonal type, containing flat-ovoid synaptic vesicles, stained only for GABA. Seventy-five days after coagulation of the vibrissal follicles in newborn mice, a characteristic multiplication of GABA positive axon terminals was observed. In addition, it was demonstrated that, similarly to modified cortical endings (Hámori et al., J. Comp. Neurol. 254:166-183, '86), many GABA positive terminals appeared as specific afferent endings, replacing the missing "specific" vibrissal afferents. This finding shows a remarkable plasticity of inhibitory GABA axons during developmental synaptogenesis and provides further evidence that the size, location, and the type of attachment of presynaptic terminals are dependent on their postsynaptic target.

Afferent Pathways↗
PubMed1990

Immunogold electron microscopic demonstration of glutamate and GABA in normal and deafferented cerebellar cortex: correlation between transmitter content and synaptic vesicle size.

Selective labeling of mossy fiber terminals and parallel fibers was obtained in rat cerebellar cortex by a glutamate antibody produced and characterized by Hepler et al. The high-resolution electron microscopic immunogold demonstration of this amino acid offered the possibility of determining the size and shape of synaptic vesicles in glutamate-positive mossy endings. Mossy terminals that stained with the glutamate antibody formed two distinct populations, one with spherical synaptic vesicles with an average diameter of 34.0 nm (more than 90% of all mossy fiber endings) and one with pleomorphic and smaller synaptic vesicles which had an average diameter of 28.5 nm. We present experimental evidence that the mossy terminals with large round vesicles are of extracerebellar origin, whereas those with small pleomorphic synaptic vesicles are endings of nucleocortical fibers. The presence of two distinct classes of gamma-aminobutyric acid (GABA)-containing axon terminals within cerebellar glomeruli has also been demonstrated; those originating from the cerebellar nuclei contain large (36.2 nm) synaptic vesicles, whereas the majority of GABA-stained axon terminals that are of local (cortical) origin contain small (29.1 nm) synaptic vesicles. It therefore appears that, at least in the case of glutamate and GABA, morphological characterization of the axon terminals based on the size and shape of synaptic vesicles is not a reliable indicator of their functional nature (i.e., whether they are excitatory or inhibitory); convincing evidence for the identity of the transmitter can be obtained only by electron microscopic immunostaining procedures. Our results also suggest the existence of both inhibitory and excitatory feedback from cerebellar nuclei to cerebellar cortex.

Animals↗
PubMed1990

[Hepatobiliary gammagraphy in the diagnosis of Dubin-Johnson syndrome in children].

Using hepatobiliary gammagraphy (99mTc-EHIDA), the authors made 26 examinations in six families with Dubin-Johnson's syndrome. From a series of gammagrams they evaluated the hepatobiliary kinetics and from measurements of the activity of series of blood samples they assessed the half-time of decline of the rapid (Tk1) and slow (Tk2) phase of the curve and the percentage of retention in blood during the 45th minute (R45). The values in a group of normal subjects were 3.4 +/- 0.6 min., 49.1 +/- 8.5 min. and 9.9 +/- 1.7%. In 12 patients with a fully developed clinical picture the liver was visualized intensively and homogeneously within 10 min., in 10 it was enlarged. The intrahepatic biliary pathways were not visualized the passage of activity into the intestinal lumen was delayed above 60 to 120 min., and the increased retention in the liver persisted for more than 120 min. The gallbladder was visualized in six but late and with low intensity. Tk1 was 4.3 to 10.0 min., R45 16.7 to 30.0%. In 9 subjects with the clinically inapparent form the visualization of the intrahepatic pathways was only indicated, the gallbladder was not visualized only in one patient. A protracted retention in the liver was in seven subjects above 60 min., in 2 above 90 min. and in 1 above 120 min. Tk1 was 4.0 to 9.0 min. and R45 12.0 to 27.1%. Hepatobiliary gammagraphy with evaluation of blood clearance of the pharmaceutical preparation is a non-invasive method which helps in the diagnosis of Dubin-Johnson's syndrome.

Adolescent↗
PubMed1979

The ultrastructure of human pituitary adenomas.

Ultrastructural examination of 28 human pituitary adenomas was performed. Findings were correlated to the clinical history and light microscopic observations. As revealed by light and electron microscopy 15 adenomas were of the chromophobe type causing no endocrine dysfunction. In 8 cases acidophilic adenomas were associated with endocrine symptoms. In this group two adenomas were of the densely granulated type, whereas 6 of the sparsely granulated type. The latter showed marked ultrastructural signs of enhanced secretory activity. Five cases corresponding electronmicroscopically to sparsely granulated acidophilic adenomas but causing no endocrine symptoms constituted a separate group. They suggest the possibility of the production of abnormal proteins by this type of adenoma cells. Oncocyte cell-groups were seen in chromophobe adenomas. Morphometric data on granule size and distribution proved to be useful in the differentiation of chromophobe and acidophilic adenomas. Hypertrophic cell organelles, filamentous and tubular structures are interpreted as ultrastructural signs of cellular adaptation.

Adenoma↗
PubMed1978

Morphological and biochemical studies on the effect of agents with liver protecting properties.

The liver protective effect of Aicaphosphate in CC1(4)-induced acute, as well as CC1(4)-and thioacetamide-induced subacute and chronic liver damages is demonstrated. The effect of the protective drugs was studied in the forms of pre-, simultaneous and delayed treatment in acute and chronic liver damages induced by various toxic agents. The degree of liver damage was determined by morphological and biochemical methods, complementary to each other. For the completion of histological studies and morphometry used for the determination of the degree of fibrosis biochemical investigations are performed. In acute liver damage the determination of DNA, protein and lipid contents of the liver tissue and the radioactive aminoacid incorporation rate should be carried out with a simultaneous analysis of the serum enzymes. In chronic liver damage, the measurement of the hydroxyproline and DNA contents of the liver give useful data for the determination of the severity of the lesion and the effect of the protective drugs, respectively.

Acetamides↗