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Biomedical subjects

A Németh

Publications and source records attributed to A Németh.

At least 19 recordsLinked to original sources
PubMed1995

[Molecular genetic markers of Alzheimer dementia].

Alzheimer's dementia (AD) is a progressive neurodegenerative disease which is one of the most common forms of dementia in the above 65 years old age group. Diagnosis is based upon evaluation of cognitive skills, elimination of other dementia associated diseases and on cranial CT examination. However, definitive diagnosis is proved only by neurohistological findings. The etiology of the disease is unknown and effective treatment is not available. Intensive research into the pathomechanism of the disease revealed a connection between increased frequency of apolipoprotein E4 allele and later onset of AD. The aim of the author's research was to characterize apolipoprotein E polymorphisms in AD patients and to examine immunological factors which could play an important role in the development of the disease such as the polymorphism of complement and lipoprotein(a) [Lp(a)] alleles previously had not been investigated. 35 AD patients (26 female, 9 male) were examined (mean age 66.4 years +/- 8.7 SD). 18 of these patients showed late onset of the disease. The E4 allele was significantly more frequent in both early and late onset groups compared to controls (0.29 vs. 0.14 and 0.33 vs 0.09). The high frequency of apo E4 found in the early onset group in this study differs from other international data. Serum lipid, lipoproteins, Lp(a) concentrations and Lp(a) phenotype distribution showed no significant difference compared to controls. Furthermore, it was found that the frequency of complement C4AQ0 (null) and Bf F alleles was higher in the late onset AD group compared to controls (0.35 vs 0.139 and 0.305 vs. 0.225) suggesting an active involvement of the complement system in the pathogenesis of this disease.

Age Factors↗
PubMed1995

[Helicobacter pylori in benign gastroduodenal diseases].

(A light- and electronmicroscopic study). We have examined the occurrence of Helicobacter pylori (HP) in 2937 gastric antral biopsy specimens from 979 patients with upper gastrointestinal symptoms. The incidence of HP proved to be 50.5%. The endoscopic diagnoses were: gastritis (62 cases), gastric erosion (425), gastric ulcer (51), duodenitis (22), duodenal erosion (119), duodenal ulcer (122) and the HP incidence was 29, 46, 63,, 50, 66 and 73%, respectively. Microscopic findings were: chronic gastritis (442), chronic active gastritis (356) and normal mucosa (181). The prevalence of HP in these groups was 43%, 78% and 11%, respectively. The activity of gastritis was in good correlation with HP infection. We did not see epithelial damage, and found only a few instances of mucus depletion. Electronmicroscopic examination was performed in order to investigate the morphology of bacterium and its relation to the mucosal cells. We observed mild loss of microvilli on the cell surface and did not see any cell invasion by bacteria.

Adolescent↗
PubMed1994

Dynamism of cytoprotective and antisecretory drugs in patients with unhealed gastric and duodenal ulcers.

A continuous multiclinical, randomized and prospective study has been carried out in our department to compare the efficacy of different cytoprotective (sucralfate, DE-NOL, Vitamin A) and antisecretory drugs (atropine, cimetidine, ranitidine, famotidine, pirenzepine) on ulcer healing in patients with chronic gastric ulcer (GU) and duodenal ulcer (DU). A total of 441 patients were randomized in different groups. The patients were treated with atropine (1 mg/day), cimetidine (1000 mg/day), ranitidine (300 mg/day), famotidine (80 mg/day), pirenzepine (50 mg/day), sucralfate (1000 mg/day), Vitamin A (3 x 50,000 IU/day) alone or in combination with cyproheptadinum (3 x 4 mg/day) DE-NOL (3 x 5 mL/day) and Tisacid (Al-Mg-hydroxycarbonicum; in different doses). Endoscopy (planimetric evaluation of ulcer sizes), measurements of clinical changes in patients' complaints, antacid consumption and laboratory tests (blood counts, urine, kidney and liver functions, electrolytes, pH status) were carried out at the beginning and 2, 4 and 6 weeks after treatment with different drugs. The incidence of ulcers, changes of ulcer sizes, subjective pain score and antacid consumption were noted at the abovementioned times. There were 20 or more patients in each group. The dynamism of ulcer healing rate was studied on the unhealed GU and DU. Our results showed that the ulcer size decreased significantly in all groups in GU and DU patients treated with cytoprotective and antisecretory drugs. Summed pain score (expressed as per cent of basic values) and antacid consumption decreased significantly in all groups. As well, some differences were found in the dynamism of ulcer healing at 2 weeks after the treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Antacids↗
PubMed1994

Phaseolus vulgaris lectin labelled and GABA immunogold stained terminals in nucleus rotundus. An EM study.

Having injected Phaseolus Vulgaris Lectin (PhA-L) iontophoretically to subpretectal (SP) and postero-ventralis (PV) thalamic nuclei, labelled fibers and terminals appeared in nucleus rotundus (Rt). The PhA-L immunostained fibers are divided dichotomically and they develop long terminal sections with large varicosities. In EM preparates PhA-L labelled terminals were observed establishing axo-somatic, axo-dendritic symmetrical synapses. These terminals were stained by GABA immunogold procedure and proved to be GABA-ergic, i.e. the neurons of SP and PV nuclei supply the principal neurons of Rt with GABA positive terminals, which are located on specific, exponent loci of the principal neuron.

Animals↗
PubMed1992

Quantitative immuno-gold labelling and ultrastructural preservation after cryofixation (combined with different freeze-substitution and embedding protocols) and after chemical fixation and cryosectioning. Analysis of the secretory organelle matrix of Paramecium trichocysts.

Among the variety of parameters affecting immuno-gold labelling efficiency, mainly the effects of different preparative protocols were tested. Preservation of ultrastructure and of antigenicity are the salient features of this study. We have labelled insoluble components of the secretory matrix of Paramecium trichocysts with specific antisera, using 10 nm colloidal gold particles. The highest labelling efficiency was obtained with fast freezing (cryofixation, either by sandwich or spray-freezing), freeze-substitution in methanol (without added fixatives) and hydrophilic Lowicryls, particularly when applied at low temperatures (K11M at 193 K). The presence of different chemical fixatives always reduced the labelling density and some recommendations from the literature do not appear advisable. Methods commencing with fixation at greater than or equal to 0 degree C, such as "progressive lowering of temperature" (PLT) or preparation of cryostat sections, i.e. with chemical pretreatments, always resulted in lower labelling density. Our data appear, therefore, relevant for optimal immuno-gold labelling of insoluble antigens and emphasize the potential of cryofixation as a primary preparation step. In addition, ultrastructural preservation was also superior after cryofixation.

Acrylic Resins↗
PubMed1992

Mechanisms of vagal nerve in gastric mucosal defense: unchanged gastric emptying and increased vascular permeability.

Gastric cytoprotection in response to different agents (prostaglandins, carotenoids, etc.) failed to occur after surgical vagotomy. Decreased gastric emptying and the increased vascular permeability were tested in ethanol-treated rats without and with bilateral surgical vagotomy. The experiments were carried out on Sprague-Dawley rats. The animals were fasted for 24 h before experiments. Bilateral surgical vagotomy or only laparatomy were carried out at 30 min before administration of ethanol (96%, 1 ml). The animals were killed at 0, 1, 5, 15, and 60 min after ethanol administration, when the number and severity of gastric mucosal lesions were noted. In another series of experiments, the animal received Evans blue (1 mg/100 g) i.v. 15 min before killing. The gastric contents were collected and the glandular mucosa was scraped. Evans blue was extracted in chloroform, and its concentration was spectrophotometrically measured. It has been found that (a) both number of lesions and severity of ethanol-induced gastric mucosal damage were larger at each time period in surgically vagotomized rats than in rats with intact vagal nerves; (b) the increased vascular permeability was significantly higher in gastric mucosa at an early period in surgically vagotomized rats compared to rats with intact vagal nerve; (c) the increased vascular events preceded the development of macroscopic appearance of gastric mucosa damage in both groups of animals; and (d) the time-related responses were the same in both groups of animals. It is concluded that increased vascular permeability, but not gastric emptying, probably has some role in the failure of the development of gastric cytoprotection in surgically vagotomized rats.

Animals↗
PubMed1992

Some data on GABA-ergic innervation of nucleus rotundus in chicks.

The EM preparates displayed in the nucleus rotundus also symmetrical type of synapses with flattened vesicles, known this type as inhibitory synapsis. To prove this supposition and to find the sources of inhibitory terminals GABA-immunostaining was applied in the diencephalon of chicks. The preparates were examined by light- and electronmicroscope. In nucl. rotundus the large terminal profiles on the cell membrane of principal neurons, on the dendrites and branching areas of terminal branchings of dendrites proved to be GABA positive. The sources of GABA-ergic fibers seemed to be the subpretectal and ventral posterior thalamic nuclei.

Animals↗
PubMed1991

Effect of phototherapy on 3H-imipramine binding sites in patients with SAD, non-SAD and in healthy controls.

The effect of incandescent light treatment on the density of 3H-imipramine binding sites (Bmax) was investigated in 17 patients with seasonal affective disorder, in eight patients with non-seasonal depression and in six healthy volunteers. A significant increase in mean Bmax value parallel to a marked improvement of the depressive symptoms was found only in patients with SAD. No effect was observed either on mean Bmax value or on clinical symptoms in patients with non-SAD and on mean Bmax value in healthy volunteers.

Adult↗
PubMed1991

Effects of photosensitization and low-power helium-neon laser irradiation on liposomes and cell membranes.

Low-power He-Ne laser irradiation causes a well-defined and energy dependent cell destruction of in vitro cultured cell lines sensitized by hematoporphyrin derivative (HPD). The mechanism of this photosensitization was studied by measuring with polarization microscopic, scanning electron microscopic, and electron-spin-resonance (ESR) spectroscopic parameters. The cell damage caused by photosensitization and laser irradiation seems to be a complex process, however the biological membranes seem to be one of the primary targets. The energy of laser light causes rotation and resonance changes of macromolecules and the water molecules, resulting in an increased structural order of the submembraneous components in the living cells, detectable microscopically. During the photosensitization process, the red (630 nm) He-Ne laser light, during a one-photon energy activation, causes excitation of hematoporphyrin molecules to their triplet state. The excitation of HPD molecules results in a multi-step, free-radical generating effect, measured by ESR spectroscopy and studied by the ultrastructural changes of membrane organization and cell shape. Similar effects could be observed on in vitro lipid-water liposome membranes.

Animals↗
PubMed1990

Inhibition of potassium-induced release of histamine from mast cells by tetraethylammonium and tetramethylammonium.

In accordance with our previous results, a marked release of histamine (HA) from rat peritoneal mast cells was initiated by 150 mM KCl in the absence of extracellular Ca2+. This release could be reduced by 20-60 mM tetraethylammonium (TEA) or tetramethylammonium (TMA), the non-selective K(+)-channel blockers, Ouabain, the general inhibitor of (Na+ + K+) ATP-ase, failed to produce any changes in this release. The action of TEA discriminated between the initiation of HA release evoked by different agents, producing a blockade of the K(+)-induced but not the 48/80-stimulated HA release. In total, these data suggest the presence of TEA/TMA-sensitive K(+)-channels in the mast cell membrane and their involvement in one of the possible pathways for the initiation of HA release.

Animals↗
PubMed1989

Broncho-Vaxom inhibits histamine release from rat mast cells induced by compound 48/80 and ionophore A23187.

Broncho-Vaxom (BV) inhibited in dose-dependent manner the release of histamine from and degranulation of isolated rat peritoneal mast cells stimulated with compound 48/80 and the ionophore A23187. Inhibition persisted after removal of BV from the incubation medium before stimulation, but did not occur when bovine serum albumin (BSA) was used instead of BV. Binding of BV to mast cells was observed by electron microscopy on cells that had been incubated with colloidal-gold labelled BV. There was no significant difference between the binding of BV gold and BSA gold to the mast cells. Washing before fixation removed most of the BV gold from the cells. This study establishes BV as an in vitro histamine release inhibitor.

Adjuvants, Immunologic↗
PubMed1989

Membrane fluidity of trophoblast cells and susceptibility to natural cytotoxicity.

This study examines the relationship between membrane lipid microviscosity and susceptibility of villous trophoblast to lysis by natural cytotoxic cells. Trophoblast-enriched cell suspensions prepared from term human placentae were treated with cholesteryl hemisuccinate (CHS)--a modulator of membrane lipid microviscosity. CHS-treated cells were more susceptible targets for natural lymphocyte cytotoxicity than were untreated controls. In binding experiments, increased binding of lymphocytes to CHS-treated target cells was found. Preincubation with progesterone prevented membrane rigidification by CHS. Progesterone, cortisol, and estriol restored the impaired resistance of CHS-treated trophoblast cells to lysis. We determined microviscosity and progesterone concentration in villous surface membranes, prepared from placentae from idiopathic spontaneous abortions and normal first-trimester pregnancies. An inverse relationship was found between progesterone content and microviscosity of the membranes. Microviscosity of the membranes from abortion placentae was significantly higher (P less than .01) and progesterone concentration was significantly lower (P less than .001) than those in the membranes of normal first trimester placentae.

Abortion, Induced↗
PubMed1989

Drug metabolism in drug-induced liver diseases: pathogenetic role of active metabolites.

Three cases with drug-induced liver diseases (hepatitis caused by hydralasine, steatosis caused by methimazole, choletasis caused by birth control pill) were investigated with respect to their drug metabolising ability. Clinical diagnoses were based on the exclusion of other pathogenetic factors, on histological findings of liver biopsy specimens and on the clinical chemical tests. Investigation of biotransforming ability was carried out using test materials (menthol loading, antipyrine, sulfadimidine, caffeine, indocyanine green kinetics) and measurement of D-glucaric acid excretion. In all cases the results show a defective capacity in some respect of drug metabolism. Possible pathogenetic role of reactive metabolites is discussed in the pathomechanism of genesis of drug-induced liver diseases.

Adult↗