Biomedical subjects

I Kovács

Publications and source records attributed to I Kovács.

At least 19 recordsLinked to original sources

PubMed2001

[Effect of ciprofibrate on the endothelial dysfunction of patients with combined dyslipidemia].

Endothelial dysfunction can be detected in the early phase of atherosclerosis. Two unresolved questions have been raised the wether, (1) the dyslipidemic state alone without any other risk factors can be harmful for the endothelial function measured by ultrasound, and (2) the use of the antilipidemic fibrate is sufficient to influence the endothelial functions. From 38 subjects with solitary combined dyslipidaemia 32 (84%) showed endothelial dysfunction measured by flow mediated vasodilatation (FMD) on the forearm and this group of patients was featured only by higher fibrinogen levels (no differences on BMI, serum lipid and glucose level). The patients with endothelial dysfunction were treated with 100 mg of ciprofibrate per day (12 women, 20 men, average age: 44.6 +/- 9 years, BMI 24.6 +/- 3.4 kg/m2). The pretreatment serum lipid levels were: total cholesterol 6.9 +/- 0.4, triglyceride 4.2 +/- 0.3, HDL cholesterol 1.13 +/- 0.21 mmol/l. After the 4 weeks treatment period the cholesterol and triglyceride level decreased, the concentration of HDL cholesterol increased significantly, which changes were in correspondence with significant improvement of FMD (3.9 +/- 0.7% vs. 7.0 +/- 1.6%). The level of fibrinogen also declined significantly. At the 8th week there were no significant further changes compared to the data received at the 4th week. Using the lineal regressive analysis the improved vasodilatator respond at both check points was correlated only with the fall of total cholesterol level. The ciprofibrate was suspended after the 8th week for a 4 weeks period and the triglyceride and the fibrinogen levels increased whereas the HDL cholesterol level decreased significantly. The FMD impaired significantly (to 5.8 +/- 1.2%). There were no correlations among the changes. The results demonstrated the lipid and probably non-lipid-factors are important in these early damages of endothelial functions.

Adult↗

PubMed2001

Quinazolone-alkyl-carboxylic acid derivatives inhibit transmembrane Ca(2+) ion flux to (+)-(S)-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid.

Comparison of the kinetics of the inward Ca(2+) ion flux to (S)-alpha-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid [(S)-AMPA] in cerebrocortical homogenates and that of the previously reported transmembrane Na(+) ion influx mediated by an AMPA receptor in hippocampal homogenates established that the agonist-induced opening of the AMPA receptor channels occurs in two kinetically distinguishable phases. Here we report that the 2-methyl-4-oxo-3H-quinazoline-3-acetic acid (Q1) inhibits the major slow-phase response specifically, whereas the acetyl piperidine derivative (Q5) is a more potent inhibitor of the fast-phase response. Both the quinazolone-3-propionic acid (Q2) and the quinazolone-3-acetic acid methyl ester (Q3) enhanced the slow-phase response to (S)-AMPA. The information provided by docking different Q1, Q2, and Q5 models at the ligand-binding core of iGluRs were used to define agonistic and antagonistic modes of interactions. Based on the effects of quinazolone-3-alkyl-carboxylic acid derivatives on specific [(3)H]Glu binding and kinetically distinguishable Ca(2+) ion permeability responses to (S)-AMPA and molecular modeling, the fast- and the slow-phase (S)-AMPA-elicited Ca(2+) ion fluxes were corresponded to different subunit compositions and degrees of S1S2 bridging interaction relative to substitution of kainate thereupon. Substitutions of agonists and antagonists into the iGluR2 S1S2 ligand binding core induced different modes of domain-domain bridging.

Acetates↗

PubMed2001

Glucocorticosteroid dependent decrease in the activity of calcineurin in the peripheral blood mononuclear cells of patients with systemic lupus erythematosus.

OBJECTIVE: To compare the activity of calcineurin in the peripheral blood mononuclear cells (PBMC) of 32 patients with systemic lupus erythematosus (SLE) and 35 healthy controls. METHODS: The activity of calcineurin was assayed in the supernatants of sonicated mononuclear cells. RESULTS: There was no significant difference in the calcineurin activity of patients with SLE not taking glucocorticosteroids (GCS) compared with the healthy controls. On the other hand, the activity of calcineurin was reduced in patients with SLE taking GCS, correlating negatively with the dose of GCS. The stimulation of PBMC by phorbol ester and calcium ionophore decreased the calcineurin activity both in patients with SLE and in healthy controls. GCS could also reduce calcineurin activity in the mononuclear cells of healthy subjects in vitro. CONCLUSIONS: In patients with SLE the decrease in the calcineurin activity of PBMC depended on the dose of GCS used for treatment, and it was not a disease specific alteration. The higher the dose of GCS, the greater the inhibition of calcineurin activity. The reduction of calcineurin activity is a new element in the immunosuppressive effects of GCS during the treatment of patients with SLE.

Adolescent↗

PubMed2001

Contour integration deficits in anisometropic amblyopia.

PURPOSE: Previous retrospective studies have found that integration of orientation information along contours defined by Gabor patches is abnormal in strabismic, but not in anisometropic, amblyopia. This study was conducted to reexamine the question of whether anisometropic amblyopes have contour integration deficits prospectively in an untreated sample, to isolate the effects of the disease from the effects of prior treatment-factors that may have confounded the results in previous retrospective studies. METHODS: Contour detection thresholds, optotype acuity, and stereoacuity were measured in a group of 19 newly diagnosed anisometropic amblyopes before initiation of occlusion therapy. Contour detection thresholds were measured using a card-based procedure. RESULTS: Significant interocular differences in contour detection thresholds were present in 14 of the 19 patients with anisometropic amblyopia. CONCLUSIONS: Contour integration deficits are a common, but not universal, finding in untreated anisometropic amblyopia. Differences in the prevalence of contour integration deficits between the present study and that of another study may lie in differences in treatment history and/or in the sensitivity of the two different contour integration tasks.

Adolescent↗

PubMed2001

[The role of percutaneous radiologic interventions in the treatment of pancreatic pseudocysts].

Authors evaluate the indications and results of percutaneous puncture and drainage of pancreatic pseudocysts. The interventions were performed in 20 patients. The first line treatment is usually surgical. Percutaneous drainage or aspiration is suggested if the patient is symptomatic, the size of pseudocyst is between 3 and 6 cms and when it can be punctured using radiological procedures, without the risk of damaging other organs. Previous peripancreatic operation, high-risk surgical intervention and the refusal of the operation by the patient should also be considered. Percutaneous drainage is an alternative method for the treatment of pancreatic pseudocysts. The advantages of this procedure are: It is minimally invasive, complications are rare and reintervention is possible. Disadvantage is high risk of recurrence.

Adult↗

PubMed2001

Decreased arachidonic acid release in peripheral blood monocytes of patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the release of arachidonic acid (AA) in unfractionated peripheral blood mononuclear cells (PBMC), separated monocytes and T lymphocytes of patients with systemic lupus erythematosus (SLE). METHODS: AA release was measured in cells from 56 patients with SLE and from 48 controls. Of the 56 patients with SLE, 38 were receiving glucocorticosteroids and 18 were not. [3H]AA was incorporated into the membranes of PBMC and purified subsets of monocytes and T lymphocytes. The release of [3H]AA was measured both in nonstimulated cells cultured for 24 h and in cell cultures stimulated by phorbol ester (PMA) and Ca2+ ionophore for 4 h. RESULTS: In the PBMC of SLE patients not taking glucocorticosteroids, the release of AA was decreased in both stimulated and nonstimulated cells. There was a decrease of AA production in monocytes but not in T lymphocytes. This phenomenon could be observed in the active and inactive phases of the disease. CONCLUSION: A defect in AA production may exist in the peripheral monocytes of patients with SLE, resulting in decreased release of AA in patients not receiving glucocorticosteroid therapy.

Adolescent↗

PubMed2000

Differences in the changes of allergen-specific IgE serum levels and the chemiluminescence of peripheral blood phagocytes in patients with allergic rhinoconjunctivitis during the ragweed season.

The objective of this study was to compare the changes in the values of allergen-specific serum IgE levels and zymosan-induced whole blood chemiluminescence (CL) in 41 patients who had exclusively only ragweed allergy in the season of acute symptoms of disease in July, August and September. All patients had allergic rhinitis or rhinoconjunctivitis. Each patient was investigated as a self-control. The ragweed-specific IgE levels were measured by enzyme immunoassay (EIA). The luminol amplified zymosan-induced CL of whole human blood was detected. The allergen-specific serum IgE levels showed slight, but not significant, gradually increasing elevations during the whole season. On the other hand, significant increases were found in the values of the basal but especially in the zymosan-stimulated CL of peripheral blood phagocytes during the acute phase of allergy. Both the basal and the zymosan-induced CL reflected significantly the activated state of the immune system. These observations clearly show that there are well detectable signs of the systemic activation of the immune system in allergic rhinoconjunctivitis beside the local alterations. In addition, the measurements of the basal and zymosan-induced CL of peripheral phagocytes could clearly reflect the clinical state of disease in vitro.

Adult↗

PubMed2000

Nuclear localization of a hypoxia-inducible novel non-symbiotic hemoglobin in cultured alfalfa cells.

We have isolated a 483-bp-long full-length cDNA clone encoding a non-symbiotic hemoglobin called Mhb1, the first one found in alfalfa. This non-symbiotic hemoglobin is a single copy gene localized in linkage group 4 in diploid Medicago genome. The Mhb1 mRNA was found only in the roots of alfalfa plants. The Mhb1 gene was inducible by hypoxia and showed no induction by cold stress treatment. The Mhb1 transcript level increased at the G2/M boundary in a synchronized alfalfa cell suspension culture. The majority of Mhb1 protein was shown to be localized in the nucleus and smaller amounts were detected in the cytoplasm. A potential link to the nitric oxide signalling pathway is also discussed.

Amino Acid Sequence↗

PubMed2000

Perceptual organization, the disorganization syndrome, and context processing in chronic schizophrenia.

Schizophrenia patients' perceptual organization abilities were assessed with a psychophysically well-controlled measure of contour integration. Compared with psychiatric and staff controls, schizophrenia patients were less able to detect contours comprising Gabor elements as the detection of these contours relied increasingly on long-range spatial interactions. Impaired task performance was also found to correlate significantly with higher levels of disorganized symptomatology. These data provide further evidence for impaired perceptual grouping in schizophrenia. In addition, the findings support the hypothesis that a common cortical processing algorithm involving contextual coordination is impaired in schizophrenia, leading to reduced binding of object features in vision, and reduced contextual disambiguation of linguistic information during thought and speech.

Adult↗

PubMed2000

[Changes of authorship characteristics in Hungarian medical publications in the period of 1967-97].

Authorship characteristics of publications appeared in the 1967-1977-1987-1997 volumes of the Orvosi Hetilap (Medical Weekly) were analysed and compared with corresponding data in the international medical literature. Following results were achieved: 1. The total number of medical publications gradually decreased although the number of pages of the volumes steadily increased during the period studied; this could be explained rather by a changed structure or editorial policy than by lowering of the readiness for publishing. 2. The number of authors per paper gradually increased over a period of forty years, the same trend was observed in the world literature as well. 3. Heads of department are more and more included among the authors; previously they gave preference to the first place, presently they figure mostly as last authors. 4. As to the origin of the communications the pattern did nor change essentially: about half of the papers came from university departments, while about 20 to 30 per cent of the authors worked in hospitals; the remaining papers were the result of cooperations. 5. Both the absolute number of ratio of the dual publication of "original" articles decreased in the last twenty years; the language used for dual publication in international journals markedly changed: while in 1967 both English and German were used with the same frequency, in 1997 English was chosen in 95 per cent of dual publications.--Results were discussed rather shortly, similar studies in the international literature were cited, but authors did not intend neither to outline their's point of view nor to to take part in the current international discussion on authorship.

Authorship↗

PubMed2000

Deramciclane inhibits N-methyl-D-aspartate receptor function.

Effects of the novel anxiolytic drug deramciclane on excitatory amino acid release and transmembrane Ca(2+) ion flux processes were compared in rat cerebrocortical homogenates containing resealed plasmalemma fragments and nerve endings. Deramciclane (10 microM) significantly inhibited [(3)H]D-aspartate release and transmembrane Ca(2+) flux to N-methyl-D-aspartate in the absence of Mg(2+). By contrast, inhibition of [(3)H]D-aspartate release and transmembrane Ca(2+) flux evoked by 0.1 mM (S)-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate in the presence of Mg(2+) and 10 microM cyclothiazide by 10 microM deramciclane was not significant. In the presence of N-methyl-D-aspartate receptor antagonists, deramciclane (10 microM) did not inhibit [(3)H]D-aspartate release to N-methyl-D-aspartate. These results suggest an involvement of the inhibition of a presynaptic N-methyl-D-aspartate receptor in the anxiolytic properties of deramciclane.

4-Aminopyridine↗

PubMed2000

[Successful surgical treatment of ruptured left ventricular aneurysm].

Authors report on the successful surgical treatment of a ruptured left ventricular aneurysm that resulted in cardiogenic shock. Pathogenesis and complications of left ventricular aneurysm as well as the diagnostic and treatment modalities are summarized. Authors emphasize that the quick and close co-operation between their departments was a prerequisite of the success.

Aneurysm, Ruptured↗

PubMed2000

A new test of contour integration deficits in patients with a history of disrupted binocular experience during visual development.

Previous studies have suggested that the integration of orientation information across space is impaired in amblyopia. We developed a method for quantifying orientation-domain processing using a test format that is suitable for clinical application. The test comprises a graded series of cards where each card includes a closed path (contour) of high contrast Gabor signals embedded in a random background of Gabor signals. Contour visibility in both normals and patients with histories of abnormal binocular vision depends jointly on the spacing of elements on the contour as well as background element density. Strabismic amblyopes show significant degradation of performance compared to normals. Small but significant losses in sensitivity were also observed in a group of non-amblyopic strabismus patients. Threshold measurements made with contrast reducing diffusers indicated that the amblyopic loss is not due to the reduced contrast sensitivity of the amblyopic eye. An abnormal pattern of long-range connectivity between spatial filters or a loss of such connectivity appears to be the primary source of contour integration deficits in amblyopia and strabismus.

Adolescent↗

PubMed2000

Human development of perceptual organization.

Two relevant dimensions are revealed within which developmental patterns of perceptual organization might be investigated. Within the local-integrative dimension, employing a contour integration task, we found indications that spatial integration develops slowly. We also found reduced contextual modulation of a local target in children employing the Ebbinghaus illusion. Within the action-perception dimension, we hypothesize a relatively slow development of the perceptual system (mediated by the ventral visual stream), as compared to the development of the action system (mediated by the dorsal visual stream). Taken together, the data indicate that long-range neuronal connectivity supporting perceptual organization in the posterior pole of the brain, and in the ventral visual pathway is not fully developed in young children.

Adolescent↗

PubMed2000

Inhibition of calcineurin activity and protection against cyclosporine A induced cytotoxicity by prednisolone sodium succinate in human peripheral mononuclear cells.

We have investigated the effects of prednisolone sodium succinate (Pss) and cyclosporin A (CSA), applied alone or concurrently, on the release of arachidonic acid (AA) (cytosolic phospholipase A(2) (cPLA(2)) activity) and on the calcineurin (CN) activity of human peripheral blood mononuclear cells (PBMC). The cytotoxic damage to the cells treated by the drugs was estimated by the release of lactate dehydrogenase (LDH). We found that Pss (10(-5) M) could inhibit the CN activity and higher concentrations (10(-4) M) could decrease the cytotoxic damage caused by CSA (10(-4) M) during their combined application. CSA had no specific effect on the release of AA from the cells. In the combined clinical use of glucocorticosteroids (GCS) and CSA, their additive inhibitory effect on CN activity and the protective membrane influence of GCS against the cytotoxicity of CSA may be beneficial.

Adult↗

PubMed2000

Kinetically distinguishable AMPA receptors in rat hippocampus are associated with the loss of glutamate-sensitive conformational transitions.

We describe a stopped-flow method to study alpha-amino-7-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-kainate receptor-mediated Na+ ion flux through native membranes. Resealed plasmalemma vesicles and nerve endings from the rat hippocampus were mixed rapidly with a membrane impermeant form of the fluorescence indicator, sodium binding benzofurane oxazole and the changes in fluorescence intensity in response to various [Glu] on the time scale of 0.04 ms-10 s were monitored at a sampling rate of 6.55 kHz. Inhibitors like ouabain (1 mM) and 5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate (dizocilpine, 50 microM) enhanced Na+ ion translocation under low-[Na+] and physiological conditions, respectively. Dependence of AMPA-kainate receptor kinetics on [Glu] was described in a model of channel activation by faster and slower desensitizing receptors. The model accounted for almost all of the Na+ ion flux activity in the 30 microM-10 mM range of [Glu]. We found that the values of the initial rate constant for Na+ ion influx, JA, and rate constant for desensitization, alpha, for the faster desensitizing receptor were dependent on data sampling rate, whereas the initial rate constant for Na+ ion flux through the slower desensitizing receptor, JB, varied much less with the sampling rate. These phenomena can be described by (1) a fractal model of short-lived AMPA-kainate receptor channel with many closely spaced states (fractal dimension approximately 1.8) and (2) a model of long-lived AMPA-kainate receptor channel with two discrete states.

Animals↗

PubMed2000

Protein phosphatase 2A holoenzyme and its subunits from Medicago sativa.

We detected an about 200 kDa holoenzyme of protein phosphatase 2A (PP2A) in the crude extract of Medicago sativa microcallus cells by gel permeation chromatography. By polymerase chain reaction (PCR) we isolated two M. sativa cDNA fragments corresponding to the catalytic (C) subunit, and one each coding for the A and the B regulatory subunits of PP2A. The C subunit sequences were different from that published previously, indicating the existence of at least three different isoforms in M. sativa. Using the PCR fragments as probes, we obtained two distinct full-length clones for both the A and B subunits from an alfalfa cDNA library. Our results demonstrate that the components of the PP2A holoenzyme, namely the catalytic and regulatory subunits, are present in alfalfa in several isoforms and that their sequences are highly similar to their plant, yeast and animal counterparts. The distinct regulatory subunit genes are constitutively expressed during the cell cycle. Interestingly, two A-B subunit pairs had parallel mRNA steady-state levels in different plant tissues suggesting that not all of the possible isoform combinations are present in all tissues. The expression of the MsPP2A Bbeta subunit form was induced by abscisic acid indicating a specific function for this protein in the stress response.

Abscisic Acid↗

PubMed2000

Inhibition of serine/threonine-specific protein phosphatases causes premature activation of cdc2MsF kinase at G2/M transition and early mitotic microtubule organisation in alfalfa.

Reversible phosphorylation of serine/threonine residues of cell cycle-regulatory proteins is one of the key molecular mechanisms controlling eukaryotic cell division. In plants, the protein kinase partners (i.e. p34cdc2/CDC28-related kinases) have been extensively studied, while the role of counter-acting protein phosphatases is less well understood. We used endothall (ET) as a cell-permeable inhibitor of serine/threonine-specific protein phosphatases to alter cytological and biochemical characteristics of cell division in cultured alfalfa cells. A high concentration of ET (10 and 50 microM) inhibited both protein phosphatases 1 and 2 (PP1 and PP2A), while a low concentration (1 microM) of ET-treatment primarily reduced the PP2A activity. High concentrations of the inhibitor increased the frequency of hypercondensed early and late prophase chromosomes that could not enter metaphase. In contrast, a low concentration of ET did not interfere with chromosomal events but caused significant alterations in the organisation of microtubules. Exposure of cells to 1 microM ET resulted in disturbance of preprophase band formation, increase in the number of nuclei with prophase microtubule assembly, premature polarisation of the spindle, and abnormal phragmoplast maturation. Under the same conditions, the ET-treated cells exhibited an early increase in cdc2MsF kinase activity. These results suggest that PP2A contributes to the control of mitotic kinase activities and microtubule organisation. Normal chromosome condensation and mitotic progression are dependent on both PP1 and PP2A activities. The presented data support the functional role of protein phosphatases in the co-ordination of chromosomal and microtubule events in dividing plant cells.

Chromosomes↗