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J Kovács

Publications and source records attributed to J Kovács.

At least 19 recordsLinked to original sources
PubMed1995

The role of cerebral microvessels in the elimination of histamine released during postasphyxial reperfusion in newborn piglets.

Histamine, released from intracerebral sources during hypoxic-ischemic conditions, may take part in the pathogenesis of neonatal brain injuries. In order to elucidate the possible role of cerebral microvessels in the elimination of histamine from the extracellular space, we determined the concentration of histamine using a modified radioenzymatic method in plasma taken from the internal jugular vein, in cerebrospinal fluid, and in capillary-rich fraction of cerebral microvessels prepared from cortex in 12 sham-operated piglets. Then, bilateral pneumothorax was induced in 20 piglets, samples were taken from the same compartments as from the controls before and during asphyxia, as well as 15 and 180 min thereafter, respectively. Plasma histamine level was significantly (P < 0.05) elevated in animals during hypoxic cardiovascular and metabolic failure (13.5 +/- 1.9 nM l-1) compared to value measured in the control group (2.2 +/- 0.5 nM l-1), preceding any detectable change of histamine concentration in cerebrospinal fluid (5.2 +/- 1.9 versus 3.8 +/- 1.1 nM l-1, respectively) or in cerebral microvessels (8.4 +/- 0.8 versus 7.1 +/- 0.6 pM (mg protein)-1). After resuscitation, histamine levels in plasma samples remained high during the early (15 min, 16.2 +/- 4.3 nM x l-1) and late (180 min, 15.3 +/- 2.9 nM l-1) reperfusion period. By contrast, histamine concentration was increased considerably (P < 0.05) in cerebrospinal fluid samples obtained 15 min (12.8 +/- 6.5 nM l-1), but not 180 min (5.2 +/- 1.9 nM l-1) after resuscitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Elastase given intracisternally opens blood-brain barrier in newborn piglets.

The effect of elastase on the blood-brain barrier (BBB) permeability was intravitally studied by fluorescence photomacroscope using the open cranial window technique in newborn piglets. Eleven animals (group 1) were given intracisternal injection of porcine elastase (1.0 micrograms), while 7 piglets served as controls (group 2). Elastase administration resulted in spotty sodium fluorescein (MW 376 daltons) extravasations in pial venules in all animals of group 1 78 +/- 4 min (mean +/- SEM) after the challenge, and in a 2-fold increase (p < 0.05) in brain sodium fluorescein uptake both in occipital cortex and white matter. The concentration of elastase-alpha 1-proteinase inhibitor complex increased significantly (p < 0.05) in cerebrospinal fluid samples in group 1, 2 and 4 h after the injection, while it did not change in sera. A significant pleocytosis and leukocytosis was also seen in group 1, while there was no change in laboratory data and BBB remained tight in group 2. BBB permeability changes during neonatal meningitis may be caused, at least partially, by elastase.

Animals↗
PubMed1995

X-irradiation-induced disorganization of cytoskeletal filaments and cell contacts in HT29 cells.

Organization of cytoskeleton and cell contacts were studied by immunochemistry and electron microscopy in confluent HT29 cultured cells following exposure to 0.5 and 1.0 Gy doses of X-ray. Microtubules were resistant to irradiation, whereas, the actin and intermediate filaments disrupted rapidly following the treatment and their components appeared as clumps of actin and cytokeratin aggregates in the cytoplasm as demonstrated by immunochemistry. Loss of cell contacts and decrease in the number of desmosomes was also characteristic of irradiated cells. Electron microscopy revealed intact desmosomes in control cells and abnormal desmosomes in the irradiated samples characterized by the absence of tonofilaments. The perinuclear filament network and cortical filaments were well detectable by electron microscopy. Under the effect of irradiation, the perinuclear filaments almost disappeared and, at the same time, small bundles of filaments were formed irregularly in the cytoplasm associated with amorphous material.

Cell Communication↗
PubMed1994

[Rare late complication of transcystic drainage].

The authors performed 3539 successful endoscopic retrograde cholangio-panreatographies between 1982 and 1992. In 1160 (32.7%) of the cases was revealed some kind of pathological condition. In connection with one case, following conventional cholecystectomy, a very rare complication was diagnosed by endoscopic means. There was a stent-like object, hanging into the duodenal lumen, through a parapapillar fistula. This was surgically removed. It turned retrospectively out that the removal of K-32 feeding tube used as a transcystic drain 18 years earlier had managed only partially. After this period of time did it cause a biliary flow obstruction and a choledocho-duodenal fistula. The endoscopic diagnostic possibilities, course of disease and treatment is presented hereby.

Adult↗
PubMed1994

Ligand-modulated cross-bridging of microtubules by phosphofructokinase.

The interaction of phosphofructokinase and microtubules results in mutual effects: decreases overall activity of the kinase and alters the ultrastructural organization of microtubules. Electron microscopic studies provide direct evidence for the periodical cross-bridges of microtubules by the kinase. 3-4 closely aligned tubules are connected by rows of highly periodic lateral arms about 13 nm long and 12 nm wide. The bundling activity of the enzyme seems to be specific since aldolase, which also interacts with microtubules, does not cross-link tubules, but it impedes the binding of the kinase to tubules. ATP, ADP and fructose bisphosphates inhibit the cross-bridges of microtubules by phosphofruktokinase to a different extent and concentration dependent manner. The kinase complexed with specific metabolites inducing distinct conformers does not interact with tubules. Microtubules cross-linked by the kinase became partly resistant to the depolymerizing action of vinblastine.

Ligands↗
PubMed1994

The role of histamine in brain oedema formation.

The effects of histamine on the cerebral endothelial cells were studied. To determine if the extent of brain oedema formation could be reduced with histamine receptor antagonists, mepyramine (H1-receptor blocker), metiamide, cimetidine and ranitidine (H2-receptor antagonists) were administered at a dose of 5 mg/kg body weight 4, 2 and 0 h before the onset of experimental pneumothorax induced in newborn piglets. Mepyramine and ranitidine given 2 h before the induction of EBP prevented the accumulation of water, sodium and albumin in samples taken from the parietal cortex. In other experiments, carried out on Sprague-Dawley rats of CFY strain after permanent bilateral common carotid ligation (BCCL), the accumulation of water and sodium in the ischemic brain tissue could also be prevented in a dose dependent manner by intraperitoneal injections of ranitidine given 30 min before the surgery. Taken together, these results provide pharmacological evidence for the involvement of histamine receptors in the pathogenesis of brain oedema. Consequently, the use of histamine receptor blockers both in the prevention and in the treatment of brain oedema can be recommended.

Animals↗
PubMed1994

Analysis of the oral manifestations of systemic sclerosis.

The oral signs and symptoms in 32 patients with systemic sclerosis were evaluated. Oral mucosal telangiectasia was present in 18 cases (56.3%) and was not restricted to the limited form of systemic sclerosis. The interincisal distance was significantly decreased in the patients with systemic sclerosis compared with the 17 controls (p < 0.001). The distance between the vermillion borders was also significantly decreased when the 14 patients with salivary hypofunction were compared with the 18 cases without decreased salivary secretion (p < 0.05). Twenty-two (69%) of the patients exhibited keratoconjunctivitis sicca, salivary hypofunction, or both. Lip biopsy was performed in 16 cases. Two cases with inflammatory signs characteristic of Sjögren's syndrome were found, and six patients showed the histologic signs of labial gland fibrosis. Five of these cases belonged to the group of limited cutaneous systemic sclerosis that indicates the generalized nature of the fibrotic processes even in systemic sclerosis with less extensive skin involvement. Of the 10 cases investigated by electron microscopy, all but one showed a thickening of the capillary basal lamina, lamellar arrangement within the basement membrane, or capillary endothelial vacuolization. Three of these cases belonged to the patients with disease onset within 2 years, showing that capillary vascular lesion is present in the early cases and that vascular injury affects even those tissues that do not seem to be evidently involved by clinical examination.

Antibodies, Antinuclear↗
PubMed1994

Effects of modulated microwave and X-ray irradiation on the activity and distribution of Ca(2+)-ATPase in small intestine epithelial cells.

The distribution and activity of Ca(2+)-ATPase were investigated by histochemical methods in small intestine epithelial cells of mice following total body 2450 MHz low frequency (16 Hz) microwave and X-ray irradiation. In the control animals, enzyme activities were found in the brush border and on lateral membranes, including junctional areas of the cells. The enzyme activity of lateral membranes was inhibited by quercetin, a specific inhibitor of Ca(2+)-ATPase. Immediately after square modulated (16 Hz) 2450 MHz microwave irradiation at 1 mW/cm2 power densities, we observed a decreased activity of Ca(2+)-ATPase on the lateral membrane regions. The X-ray irradiation (1 Gy) induced a similar decrease of Ca(2+)-ATPase activity which was reversible within 24 hours. "5 Gy" doses resulted in a decrease of enzyme activities on both apical and lateral membrane areas persisting up to 24 hours following irradiation.

Animals↗
PubMed1993

Immunogold localisation of ubiquitin-protein conjugates in Sf9 insect cells. Implications for the biogenesis of lysosome-related organelles.

Immunogold electron microscopy with antibodies which primarily detect ubiquitin-protein conjugates shows conjugate-specific gold particles enriched severalfold in acid phosphatase-positive lysosomes and multivesicular bodies in insect Sf9 cells. The observations demonstrate that ubiquitinated proteins are associated with small acid phosphatase-containing primary lysosomes (transport vesicles) and indicate a pathway in which primary lysosomes fuse with multivesicular bodies to generate mature lysosome-related structures.

Acid Phosphatase↗
PubMed1993

[New cases of celiac disease detected by anti-endomysial antibody test in families of gluten-sensitive patients and among children examined for non-specific gastrointestinal complaints].

Among 228 relatives of 101 gluten-sensitive patients, 13 anti-endomysium antibody (EmA) positive persons (7 children and 6 adults) were identified. In 12/13 cases jejunal biopsy confirmed severe villous atrophy consistent with celiac disease. In the single EmA positive sibling without villous atrophy the histology is thought to be influenced by a steroid treatment because of pulmonary disease. By routine EmA-testing 12 unexpected EmA positive patients were found out of 756 children with complaints and laboratory results otherwise not justifying jejunal biopsy at the first evaluation. Their initial diagnoses were: proteinuria, colitis, Crohn's disease, rickets, recurrent vomiting, resolved postinfectious lactase deficiency, "previously excluded" celiac disease. Severe villous atrophy could be demonstrated in all EmA positive patients subsequently. In further 204 EmA negative children the biopsy showed no atrophy. EmA positivity may reveal clinically not apparent severe villous atrophy emphasizing the role of a new non invasive and highly specific serological screening method for celiac disease.

Adolescent↗
PubMed1993

Escherichia coli 0111 B4 lipopolysaccharide given intracisternally induces blood-brain barrier opening during experimental neonatal meningitis in piglets.

Neonatal bacterial meningitis remains a life-threatening infection, and severe neurologic sequelae may be left in survivors as well. The goal of the study was to develop and characterize a porcine model of the disease with intravital observation of the permeability changes in cerebral microvessels. Eighteen newborn piglets were given doses of 0 ng (group 1), 20 ng (group 2), and 200 ng (group 3) of Escherichia coli 0111 B4 endotoxin (LPS) intracisternally (n = 6 in each group). Cardiovascular parameters were without changes, but a compensated metabolic acidosis occurred in group 3 4 h after LPS injection. Using the open cranial window technique combined with fluorescence excitation, there was no blood-brain barrier leakage in pial-arachnoid microvessels for sodium fluorescein during the 4 h of experiments in group 1 piglets, whereas spotty extravasations occurred in group 2 and in group 3 after the LPS injections (70.5 +/- 10.5 and 55.2 +/- 4.1 min, respectively, mean +/- SEM). A dose-dependent increase in sodium fluorescein uptake in brain regions examined (parietal and occipital cortex, cerebellum, and periventricular white matter) was also found by fluorescence spectrophotometry. LPS-treated piglets had developed pleocytosis. Four h after the challenge, the white blood cell counts in cerebrospinal fluid were (mean +/- SD): group 1, 8.2 +/- 7.6 microL-1; group 2, 453 +/- 703 microL-1; and group 3, 1 027 +/- 620 microL-1, respectively, whereas there was no change in white blood cell count of peripheral blood samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Morphological and histochemical changes in intercellular junctional complexes in epithelial cells of mouse small intestine upon X-irradiation: changes of ruthenium red permeability and calcium content.

Changes of calcium-content and permeability of tight junction following X-irradiation were investigated in mouse intestinal epithelial cells by electron microscopy. In the control animals the lower parts of tight junctional area as well as the other junctional elements and the intercellular space are labeled by pyroantimonate precipitates, which contain calcium as revealed by electron spectroscopy and electron energy loss spectrometry. X-irradiation, parallel with morphological changes, lead to rapid decrease of pyroantimonate precipitable calcium content and increase of the permeability of tight junctions indicated by the penetration of ruthenium red into the intercellular space. These changes were readily reversible following 0,5 Gy doses of irradiation however, they persisted up to 24 hours following 5 Gy irradiation. We conclude that irradiation at the applied doses can transiently destabilize the tight junctions in the epithelial layer of the small intestine, presumably through a calcium dependent mechanism.

Animals↗
PubMed1993

Effects of modulated and continuous microwave irradiation on pyroantimonate precipitable calcium content in junctional complex of mouse small intestine.

The pyroantimonate precipitable calcium content of intestinal epithelial cells was investigated in mice following total body irradiation with 2450 MHz continuous and low frequency (16 Hz) square modulated waves. In the control animals the reaction products appeared in the intercellular space of adjacent cells including intermediate junctions and desmosomes and were absent in the area of tight junctions. Immediately after low frequency modulated microwave irradiation at 0.5 and 1mW/cm2 power densities, a rapid distribution of pyroantimonate precipitable calcium content was observed. The pyroantimonate deposits were located on the cytoplasmic side of lateral membrane, in the area of junctional complex, including tight junction, and in other parts of lateral plasma membrane. These changes were reversible and 24 hours after the irradiation the distribution of pyroantimonate deposits was similar to the control. Continuous waves with same energy not altered the distribution of precipitable calcium. We conclude the low frequency modulated microwave irradiation can modify the calcium distribution without heat effects.

Animals↗
PubMed1992

Recombinant human tumor necrosis factor alpha constricts pial arterioles and increases blood-brain barrier permeability in newborn piglets.

Tumor necrosis factor alpha (TNF alpha) plays a significant role in the pathogenesis of central nervous system infections. We investigated the effect of intracisternal injection of recombinant human TNF alpha (50-50,000 IU) on pial vasoreactivity and blood-brain barrier permeability in newborn piglets. The cytokine administration resulted in arterial vasoconstrictions, blood-brain barrier opening for Na-fluorescein (mol. wt. 376 Da) and increased Na-fluorescein uptake in brain regions examined (parietal and occipital cortex, cerebellum, pons/medulla, periventricular white matter) in a dose-dependent manner. TNF alpha may be involved in the pathophysiology of neonatal brain injuries.

Animals↗