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Biomedical subjects

G Adám

Publications and source records attributed to G Adám.

At least 19 recordsLinked to original sources
PubMed1992

The influence of monocular viewing on heart period variability.

Monocular viewing seems to differentially activate the cerebral hemispheres. Viewing with only one eye is accompanied by a relatively greater activation of the contralateral hemisphere. In this study heart periods were measured during binocular, left and right monocular viewing in 29 right-handed males. Power spectral analysis of heart period variability showed that the amount of heart rate fluctuations in the 0.07-0.13 Hz frequency range (the mid-frequency peak of the spectrum) depends on the viewing eye. Only viewing with the left eye produced a significant increase of the mid-frequency peak. It is known that sympathetic activity contributes strongly to the mid-frequency component of the heart rate. Therefore, it is concluded that the effects of left monocular viewing result in an increased sympathetic influence on the sinoatrial node.

Adolescent↗
PubMed1992

Mouse microtubule-associated protein 2 expression in transgenic Drosophila.

Full-length mouse microtubule-associated protein 2 complementary DNA inserted between Drosophila heat-shock protein 70 promoter and trailer was introduced in the germ-line of Drosophila melanogaster by P element-mediated transformation. Three transformant lines contained microtubule-associated protein 2 complementary DNA in sense orientation and two in antisense orientation. All sense lines produced microtubule-associated protein 2 after heat-shock in several tissues at low level. In the adult brain, high-level microtubule associated protein 2 expression independent of heat induction occurred in specific neuron types in each sense transformant, suggesting the action of neuron-specific enhancer genes. High microtubule-associated protein 2 levels are expected to interfere with the cells' activity by forming unphysiological cross-links, which may help elucidate the function of the given neurons.

Animals↗
PubMed1990

Hemispheric preference and obesity.

This study investigated the relationship of hemispheric preference--the tendency to activate one hemisphere rather than the other--and obesity, on 37 right-handed, male university students. Hemispheric preference was assessed by the directionality of conjugate lateral eye movements, and the degree of obesity was determined by the body mass index (BMI). The results showed that right hemisphere preferent subjects ("left-movers") are less obese than left hemisphere preferents ("right-movers").

Adolescent↗
PubMed1990

The effect of lateral visual fixation and the direction of eye movements on heartbeat discrimination.

This study was undertaken to determine whether the asymmetrical activation of the two cerebral hemispheres affects the accuracy of heartbeat perception. Hemispheric preference--the tendency to activate one hemisphere rather than the other--was assessed by the directionality of conjugate lateral eye movements. Actual differential hemispheric activation was achieved by contralateral visual fixation. The results of 44 right-handed male subjects showed that right hemisphere preferent subjects ("left-movers") performed better on a heartbeat discrimination task than left hemisphere preferent subjects ("right-movers"). The direction of lateral visual fixation also influenced heartbeat discrimination: subjects fixating to the left were more accurate than those fixating to the right.

Adolescent↗
PubMed1990

Detection of colon distension in colonostomy patients.

Inborn and learned ability to detect mild, nonpainful distension of the sygmoid colon was examined in 22 patients who underwent colonostomy one year or more before the investigation. The colon was distended by a balloon inserted 10 cm below the orifice of the artificial anus. Each subject participated in three sessions on three consecutive weeks with several experimental tasks in each session. During each task, the patient received the colon stimulus (the "signal") 25 times randomly paired with masking auditory or annular skin stimuli (around the stoma or 15 cm medially to it). The masking (warning) stimuli were administered in series of 50, representing the "noise," according to signal-detection paradigms. The subjects had to indicate after each administration of the warning noise stimulus whether or not they thought the colon stimulus had been presented. In all three sessions, learning tasks were included using reinforcement of successful detection trials. Seven subjects out of 22 were considered good perceivers, 9 persons were considered medium perceivers, and the remaining 6 subjects were considered poor perceivers. According to the data of the first two groups, it can be hypothesized that most patients have some inherent sensitivity of colon distension, and that learning improves this initial ability. However, the role of skin, peritoneal, or interstitial receptors in colon distension detection cannot be excluded.

Adult↗
PubMed1988

Casein kinases I and II bound to pig brain microtubules.

1. Microtubules prepared from pig brain by two cycles of assembly-disassembly comprise cyclic nucleotide-independent protein kinase activity with phosvitin and troponin T as substrates. 2. Phosphocellulose chromatography resolved two phosvitin kinase activity peaks, one of which coincided with the troponin T kinase peak. 3. The activity peak corresponding to troponin T kinase was inhibited by heparin (I50 = 0.06 micrograms/ml), whereas the other phosvitin kinase peak was unaffected. 4. Both kinase fractions phosphorylated tubulin and microtubule-associated protein (MAP-2). 5. It is concluded that pig brain microtubules contain bound casein kinases I and II. The association may target the action of these kinases toward microtubular proteins in vivo.

Animals↗
PubMed1988

Microtubule-associated cyclic AMP-dependent protein kinase in Drosophila melanogaster.

Microtubules were prepared from head extracts of the adult fruit fly, Drosophila melanogaster, by one-step, taxol-assisted polymerization. The microtubular fraction displayed cyclic AMP-dependent protein kinase (protein kinase A) activity, as witnessed by endogenous protein phosphorylation and by protein kinase assay. Microtubule-bound protein kinase A amounts to 4-5% of total soluble kinase activity, which is almost an order of magnitude less than in mammals. The high-molecular-weight microtubule-associated protein-2 (MAP-2), the main binding species for protein kinase A in mammalian brain microtubules, is not detectable in the fly system by protein staining and immunoblotting with anti-pig MAP-2 serum, as well as by hybridization of fly DNA with a cDNA probe for human MAP-2. Cyclic AMP removes a major part of the regulatory (R) subunit of the enzyme from Drosophila microtubules, as demonstrated by enzyme assay, autophosphorylation of R subunit, and quantitating cyclic AMP binding sites. It is proposed that permanently elevated cyclic AMP levels may elute protein kinase A from crucial intracellular binding sites, thereby interfering with signal transduction.

Animals↗
PubMed1986

Blood-brain barrier damage during the acute stage of subarachnoid hemorrhage, as exemplified by a new animal model.

Models have been devised and characterized in the laboratory rat for studying the neuropathology of subarachnoid hemorrhage. Several ways of injecting blood via different routes have been tried; cortical subarachnoid administration is the most reproducible suitable model. The location of injected blood was detected in histological sections. In this rat model for subarachnoid hemorrhage, the arterial blood pressure and the intracranial pressure did not elevate significantly, and the influence of major ischemic components in the development of brain edema could also be ruled out. Measurements performed on the water, electrolyte, and albumin contents of brain tissue have clearly indicated that the brain edema developing in the acute stage of rat experimental subarachnoid hemorrhage could be classified as having a primarily vasogenic component as well. These findings may have implications in the treatment of subarachnoid hemorrhage.

Acute Disease↗
PubMed1985

Kainic acid neurotoxicity: characterization of blood-brain barrier damage.

The alterations in the water, sodium (Na) and potassium (K) contents of the frontoparietal cortex, hippocampus and thalamus as well as the protein permeability of the blood-brain barrier were investigated in rats 4 h after systemic kainic acid administration. Increases in the water and Na contents and a decrease in the K content were observed together with Evans blue extravasation in the thalamus area indicating the development of vasogenic brain edema. Changes observed in the ion contents of the frontoparietal cortex and hippocampus may be due to a general cell membrane permeability damage but are not caused by a primary disturbance of the blood-brain barrier.

Animals↗
PubMed1984

Prevention by macrocortin of global cerebral ischemia in Sprague-Dawley rats.

We have previously shown that dexamethasone protects female Sprague-Dawley CFY rats against global cerebral ischemia induced by bilateral carotid artery ligation. In the present study, macrocortin derived from rat peritoneal cells exposed to dexamethasone was found to exhibit antiphospholipase A2 activity and to provide significant protection against the fatal consequences of carotid artery ligation. These results suggest that the cerebroprotective effect of glucocorticoids may be related to macrocortin production.

Animals↗
PubMed1984

Cerebroprotective effect of dexamethasone by increasing the tolerance to hypoxia and preventing brain oedema in newborn piglets with experimental pneumothorax.

The effect of dexamethasone (DXM) pretreatment in newborn piglets with experimental pneumothorax (EPT) was studied. Neither low DXM doses nor those administered 1 or 2 h prior to the induction of EPT were found to be effective against its course. In contrast, 5 mg/kg of body wt. of DXM given subcutaneously 4 h prior to EPT improved significantly both the tolerance and laboratory data of the animals. The extent of brain oedema, measured 4 h after recovery, was also considerably lowered. Actinomycin D pretreatment prevented almost completely the beneficial effect offered by DXM suggesting the involvement of newly synthesized protein(s) in the cerebroprotective effect of DXM.

Animals↗
PubMed1984

The blood-brain barrier in hypoxia: ultrastructural aspects and adenylate cyclase activity of brain capillaries.

The ultrastructure of brain microvessels, their permeability to serum albumin, the activities of some endothelial enzymes and the effect of histamine were investigated in rats after a prolonged hypobaric-hypoxic treatment. After prolonged hypoxia, the permeation of serum albumin into endothelial cells increased together with the number of pinocytotic vesicles of the endothelium. Intracarotid histamine stimulated this process even further, and its effect was mediated by H2-histamine receptors. After hypoxia the specific activity of capillary alkaline phosphatase and gamma-glutamyl transpeptidase remained unchanged, while that of adenylate cyclase was greatly increased. Histamine did not modify the structure of tight junctions of isolated capillaries of normoxic animals. Both hypoxia- and histamine-induced modification of the brain microvessels were accompanied by an increase of pinocytosis, which may be stimulated by the activation of capillary adenylate cyclase.

Animals↗