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Biomedical subjects

M Tóth

Publications and source records attributed to M Tóth.

At least 91 records · Page 5Linked to original sources

[Endocrinologic complications of neurofibromatosis type 1].

Neurofibromatosis type 1 is the most common autosomal dominant inheritable disease, which is often associated with secondary forms of hypertension and with tumors of neuroectodermal origin. The authors present the results of evaluation of 60 members of 3 families. Of the 60 family members, 13 subjects had symptoms of neurofibromatosis type 1 disease, of which 7 subjects were evaluated. The case histories of patients are discussed: (1) An incidentally discovered adrenal tumor was proved to be a pheochromocytoma. (2) Because of complaints similar to thyrotoxicosis, thyrostatic drugs were administered for years without effect and, finally, an adrenal phaeochromocytoma was diagnosed after the presence of neurofibromatosis was established. (3) Preeclamptic pregnancy of a young primigravida complicated with severe HELLP syndrome (hemolysis-elevated liver enzymes-low platelet count) led to thorough evaluation which revealed renal artery stenosis. In this patient, percutaneous renal artery angioplasty resulted in a complete cessation of hypertension. (4) Glucocortocoid replacement therapy in a patient with neurofibromatosis type 1 resulted in a complete normalization of both secondary adrenal insufficiency and a previously unexplained iron-refractor iron-deficient anemia. The case histories of the patients demonstrate a lack of in-depth knowledge of neurofibromatosis in clinical practice. A regular follow-up of neurofibromatosis patients is suggested in specialized health centers.

Adrenal Gland Neoplasms↗

Population-based case control study of folic acid supplementation during pregnancy.

Previous studies have demonstrated that periconceptional folic acid/multivitamin supplementation reduced the occurrence of neural tube defects. A case control analysis has been conducted in the dataset of the Hungarian Case Control Surveillance of Congenital Abnormalities, 1980-1991. In the study period, 54.9% of 30,663 pregnant women who had healthy babies (negative control group) were supplemented with high doses (in general 2 x 3 mg) of folic acid per day. In those 17,300 pregnant women who had offspring with congenital abnormalities, the rate of folic acid supplementation was 50.4%. Exposure histories: preconceptional, I, II, III, and IV-IX postconceptional months were determined by record reviews and questionnaire assessment. The case control pair analysis showed a significant protection after folic acid supplementation during the critical period of cardiovascular defects, neural tube defects, cleft lip with or without cleft palate and posterior cleft palate.

Case-Control Studies↗

Continuous production of ethanol using yeast cells immobilized in preformed cellulose beads.

Saccharomyces cerevisiae cells were immobilized on preformed cellulose beads by adsorption. The fermentation capacity of the immobilized yeast cells was found to be practically independent of the hydrogen ion concentration between pH 3.1 and 6.25. The fermentation capacity was maximal at 30 degrees C. The immobilized yeast cells were used for continuous production of ethanol in a fluidized-bead reactor. The average values characteristic for the process were an ethanol concentration of 41.9 +/- 0.1 g1(-1), a fermentation efficiency of 82.9 +/- 2.1% and a volumetric productivity of 3.94 +/- 0.52 g1(-1) h-1.

Adsorption↗

Optimization of blends of synthetic pheromone components for trapping male limabean pod borers (Etiella zinckenella Tr.) (Lepidoptera: Phycitidae): preliminary evidence on geographical differences.

From the five previously identified pheromone components of the limabean pod borer (Etiella zinckenella Tr.) (Lepidoptera: Phycitidae), the 100:3 mixture of (Z)-11-tetradecenyl acetate and (Z)-9-tetradecenyl acetate was necessary for maximal attraction of males into traps in tests performed in Hungary. The addition of (E)-11-tetradecenyl acetate in percentages higher than 10-30% generally had an adverse effect on catches, while the addition of the other two compounds present in pheromone extracts had no influence on catches. In contrast to the results in Hungary, none of the traps baited with combinations of the above compounds captured any moths in tests performed in Taiwan, suggesting possible geographical differences in pheromonal response of European and Eastern Asian populations of E. zinckenella.

Animals↗

Calcium-dependent nitric oxide synthesis is potently stimulated by tetrahydrobiopterin in human primordial placenta.

Homogenized first trimester human placenta exhibits both Ca(2+)-dependent (90-95 per cent) and Ca(2+)-independent (5-10 per cent) nitric oxide (NO)-synthesizing activities. Addition of tetrahydrobiopterin (BH4) to homogenates containing Ca2+ in maximally activating concentrations (> 0.5 microM) results in a further 2-2.5-fold activation of NO synthesis, with half-maximal stimulation observed at 26 +/- 8.2 microM BH4 (mean +/- SEM, n = 4). Chelation of Ca2+ in the medium abolishes the stimulatory effect, indicating that only a Ca2(+)-dependent NO-synthase (NOS) isoform is activated by BH4. Based on our previous findings, we suggest that this isoform is the endothelial or Type III NOS. Importantly, BH4 has no significant effect on the Ca2(+)-dependency of NOS activity, the apparent Km values for Ca2+ are comparable in the absence (1.8 +/- 0.4 microM, mean +/- SEM, n = 6) or presence (2.5 +/- 0.6 microM, mean +/- SEM, n = 6) of 50 microM BH4. The BH4 content of these placentae is 207.4 +/- 86.7 pmol/g wet tissue (mean +/- s.d., n = 9), therefore, BH4 added to the homogenate does not simply restore the concentrations that occur endogenously. The results provide the first evidence that in the early human placenta, a constitutively expressed CA 2(+)-dependent NOS isoform is stimulated by exogenous BH4, raising the possibility that BH4 is an important regulator of NOS activity in this tissue. This novel aspect of the NO-generating pathway may have implications in the aetiology and treatment of pregnancy-induced hypertension and pre-eclampsia.

Arginine↗

Granulomatous hypophysitis associated with Takayasu's disease.

We report a case of Takayasu's disease, presenting with symptoms of fever, anaemia, elevated erythrocyte sedimentation rate, anterior pituitary failure and mild diabetes insipidus. A pituitary mass with suprasellar extension mimicking a pituitary adenoma was found, and histological examination revealed granulomatous hypophysitis. The diagnosis of Takayasu's disease was established after the development of a multiple arterial occlusive disease. We suggest that Takayasu's disease should be considered in the differential diagnosis of granulomatous hypophysitis of unknown origin.

Blood Sedimentation↗

Production of ouabain by rat adrenocortical cells.

Our aim was to identify which adrenocortical cells produce ouabain and how it is regulated in vitro. With the help of an ouabain radioimmunoassay developed in our laboratory, we found that ouabain is produced both by zona glomerulosa and fasciculata cells. Our results were confirmed by reverse-phase HPLC. ACTH increased ouabain production in both cell types. Angiotensin-II, as well as changes in the potassium concentration of the incubation medium, affected ouabain production only in the zona glomerulosa.

Adrenal Cortex↗

Prostaglandin E2 activates phospholipase C and elevates intracellular calcium in cultured myometrial cells: involvement of EP1 and EP3 receptor subtypes.

PGE2 is a powerful modulator of uterine contractility, but there is uncertainty as to which receptor subtypes (EP1, EP2, EP3, or EP4), G proteins, and second messenger systems are activated by PGE2 in myometrium. Here we show that in cultured human myometrial cells, PGE2 (1-100 microM) activates phospholipase C (PLC) up to 500% over the control level and elevates intracellular calcium ([Ca2+]i) from the resting level of 60-90 nM up to 350 nM in a concentration-dependent manner. Stimulation by the receptor subtype-selective analogs GR63799X (EP3), sulprostone (EP3 > EP1), and misoprostol (EP3 > EP2 > EP1) indicates that these effects are transmitted through EP3 receptors. Both effects are resistant to pertussis toxin (PT). Lower concentrations of PGE2 (1-300 nM) increase [Ca2+]i via a PT-sensitive pathway, without PLC activation. This [Ca2+]i increase occurs after an inverse dose-related delay and is inhibited by the selective EP1 antagonist AH6809 and calcium channel blockers. By comparison, oxytocin stimulates PLC up to 1000% over the control level and elevates [Ca2+]i up to 800 nM in a concentration-dependent manner without any measurable delay; both effects are partly sensitive to PT. These data provide functional evidence for the presence of different stimulatory mechanisms for PGE2 in myometrium: 1) a low affinity receptor (probably EP3D) that activates PLC through a PT-insensitive pathway; and 2) a high affinity receptor (probably EP1), independent from PLC and involving a PT-sensitive G protein (G(i)?). Both pathways lead to elevation of [Ca2+]i.

Calcium↗

Human brain microvessel endothelial cell culture as a model system to study vascular factors of ischemic brain.

Cerebral ischemia is caused by reduced blood supply at the microcirculatory level. In the microvessels, the main elements of the reperfusion injury following brain ischemia are the transformation of endothelial cell-surface from anticoagulant to procoagulant property, leukocyte adhesion, sludge or clot formation. There is a paucity of information on how hemostatic factors, cytokines, lipoprotein(a) (Lp(a)) and endothelin-1 (ET-1), being responsible for ischemic/reperfusion injury, interact with human brain microvessel endothelium (HBEC). There are no data furthermore about the expression of complement proteins of HBEC influenced by cytokines or fibrinolytic factors. Previously we established optimal conditions for culturing HBEC. Cell contraction induced by thrombin, plasmin, miniplasmin was recorded. The reassembly of F-actin was observed after thrombin treatment. ICAM-1 upregulation was measured following TNF-alpha, IL-1-alpha and thrombin incubation. Plasmin and miniplasmin downregulated the ICAM-1 in our cell culture system. Lp(a) modulated the thromboresistant cell-surface by reduction of t-PA and u-PA, but PAI-1 remained unchanged. Lp(a) modulated the ET-1 production by early increasing and late decreasing, in a bimodal manner. The increased secretion of ET-1 by cytokines (TNF-alpha, IL-1-alpha) was reduced in the presence of Lp(a). Gradual increase of complement proteins (factor H, factor B, C4) was induced by cytokines. Plasmin and miniplasmin augmented a rapid increase of C4. Some factors of complex relationship between regulators and modulators of endothelial adhesion molecules have been demonstrated in a human cell culture system prepared from brain microvessel endothelium. A unified concept of sequential events of ischemia/reperfusion in the brain has not yet developed.

Biological Factors↗

Phosphatidylcholine cycle: an intracellular signaling mechanism in the primordial human placenta.

The effects of 4 beta-phorbol-12-myristate-13-acetate (PMA) and 1,2-sn-dioctanoylglycerol (DOCG) on the rate of labeling of phosphatidylcholine (PC) with (32P)phosphate and the rate of formation of (3H)phosphatidylethanol (PET) from PC labeled with (3H)myristic acid were investigated in vitro in minced placentae obtained from first trimester human pregnancies. Maximally effective concentrations of PMA (1 microM) or DOCG (125-250 microM) stimulate PC-labeling with (32P)phosphate along different time courses: responses to DOCG and PMA require 30 and 60 min, respectively. The early response to DOCG is attended by a rapid accumulation of 32P)PCDOCG followed by a decline from the peak value in the second 30 min. The PMA effect is accompanied by increased rate of formation of (32P)phosphatidic acid (PA). Importantly, the effects of PMA and DOCG on PC-labeling are additive and PMA does not have any effect on the labeling of PCDOCG. These findings indicate that PMA stimulates degradation and the attendant turnover of PC, whereas a greater part of the DOCG-effect comes from the stimulation of PC synthesis de novo. Consistent with this notion is the finding that PMA enhances the PC-selective phospholipase D activity (measured by the formation of PET) 2.4-fold, whereas the effect of DOCG is smaller (1.4-1.8-fold) and not additive with that of PMA. The results provide evidence for the presence of functional PC-cycle in the primordial human placenta. The cycle can be triggered by a single addition of PMA and to a lesser extent by DOCG. The smaller effect of DOCG may be related to its short lifetime in the tissue, which is sufficient, however, to stimulate the activity of the regulatory enzyme (CTP: choline cytidylyl transferase) of PC synthesis. Since the effect of PMA on PC-labeling is diminished by protein kinase C inhibitors, this enzyme appears to be involved in the stimulation of PC-cycle by DAG and its analogs.

Diglycerides↗

Effect of chlorpromazine on the synthesis of neutral lipids and phospholipids from [3H]glycerol in the primordial human placenta.

Addition of chlorpromazine (CPZ) of 100 microM final concentration to fragments of primordial human placenta incubated in vitro with [3H]glycerol results in the following changes in the labelling of various neutral lipids and phospholipids: (1) rapid accumulation of [3H]phosphatidic acid (PA) to a 2.31 +/- 0.12-fold (mean +/- s.d., P < 0.05) higher steady-state level within 5 min; (2) a dramatic, 5-6-fold (5.74 +/- 0.31, P < 0.01) increase in [3H]phosphatidylinositol (PI) synthesis within 5-10 min, followed by progressive PI accumulation; (3) gradual accumulation of [3H]1,2-diacylglycerol (DAG) reaching approximately 1.7-fold (1.72 +/- 0.14, P < 0.05) higher steady-state level at 30 min; and (4) an approximately 20 and 30% decrease in [3H]triacylglycerol (TG) and [3H]phosphatidylcholine (PC) formation, respectively, which begins to become evident between 10-30 min. As dose-response studies indicate, accumulations of PI and DAG are most susceptible to CPZ. They respond in the concentration range of 10-50 microM, while only higher drug concentrations (100-250 microM) affect the synthesis of PA, PC and TG significantly. Finally, dioctanoylethyleneglycol (DOEG), a structural analogue of the diacyl moiety of PA and DAG, selectively inhibits the basal synthesis (0.59 +/- 0.15, P < 0.05) as well as the CPZ-induced rise (0.49 +/- 0.11, P < 0.02) of PI. These results suggest that CPZ-induced increase in the concentrations of PI and 1,2-DAG may interfere with signal-transduction pathways in the placenta of pregnant patients treated with CPZ. Furthermore, DOEG is able to antagonize the CPZ effect which directs lipid biosynthesis towards the formation of PI.

Chlorpromazine↗

Effects of Asp-179 mutations in TEMpUC19 beta-lactamase on susceptibility to beta-lactams.

To examine the effect of disruption of the salt bridge (between Arg-164 and Asp-179 [numbering of Ambler et al. (Biochem J. 267:269-272, 1991)]) that anchors the conserved omega-loop in class A beta-lactamases, we obtained mutant enzymes with each of the 19 other amino acid residues replacing Asp-179 in the TEM beta-lactamase encoded by pUC19 and studied the level of resistance to various beta-lactams conferred by each enzyme. All mutations of Asp-179 compromised the level of resistance to ampicillin, but most of them enhanced resistance to ceftazidime. In contrast, mutations of Asp-179 generally impaired the low levels of resistance to cefepime and aztreonam. One might expect to find clinical isolates with mutant TEM beta-lactamases with replacements of Asp-179 that express an expanded spectrum of resistance to beta-lactams including ceftazidime.

Ampicillin Resistance↗

Ventricular tachycardias induced by intracoronary administration of endothelin-1 in dogs.

In 12 anesthetized, open-chest mongrel dogs, endothelin-1 (ET-1) was infused into the left anterior descending coronary artery through an indwelling catheter at a dose of 30 pmol.min-1 for 30 min (n = 8). In four dogs the ET-1 dose was increased to 60 pmol/min for 10 min. Programmed electrical stimulation was used for electrophysiologic studies. Coronary blood flow was reduced by 32% on average without any ischemic ECG signs. QT time (186 +/- 3 ms vs. 218 +/- 6, p < 0.05, and 225 +/- 9, p < 0.05, p < 0.05). Ventricular irritability increased in all cases; ventricular extrasystoles, and nonsustained and sustained tachycardias occurred and, in 11 cases, ventricular fibrillation terminated the experiments. In two dogs, early afterdepolarization was recorded. Therefore, ET-1 is capable of inducing fatal ventricular arrythmias at least partly independent of its vasoconstrictor effect. QT prolongation appears to have a pathophysiologic role in this arrythmogenic effect.

Action Potentials↗

Human pericardial fluid contains the highest amount of endothelin-1 of all mammalian biologic fluids thus far tested.

Immunoreactive endothelin-1 (ET-1) levels were measured in the pericardial fluid (PF), plasma (PL), and atrial and ventricular tissues of 16 cardiac surgical patients. ET-1 was higher in the PF (73 +/- 11 pg/ml) than in the PL/3.33 +/- 0.51 pg/ml; p < 0.05/. PF/PL ratio ranged from 8 to as high as 200. An inverse relationship was found between the NYHA stage and ET-1 concentrations in PF, whereas ET-1 in PL did not have any relation to the NYHA stage of the disease. In HPLC analysis, the total immunoreactive ET-1 in PF from five different patients co-eluted with the human ET-1 standard. The results indicate that ET-1 concentrations in human PF can be several-fold those in the PL. The source and function of the ET-1 in PF requires further investigation.

Body Fluids↗

Effects of chlorpromazine on the rate of synthesis of various glycerolipids from [3H]glucose in the human primordial placenta.

The in vitro effect of chlorpromazine (CPZ) on the biosynthesis of various neutral and phospholipids of the 8-10 week old human placenta from [3H]glucose has been studied. Time course (with 0.5 mM CPZ) and dose-response (with 0.1-1.0 mM CPZ) experiments were performed. In order to investigate the significance of the cationic nature of CPZ, the effects were compared with those of 0.05% (v/v) Triton X-100, a nonionic amphiphile, and with the effects of the combined treatments with CPZ and Triton. The results provide evidence that (I) CPZ and Triton stimulate the formation of phosphatidic acid (PA) from glucose, (II) CPZ but not Triton inhibits the activity of phosphatidic phosphohydrolase (PPH), (III) both compounds inhibit the activity of diacylglycerol (DAG)-acyltransferase with an attendant rise of the levels of DAG and phosphatidylcholine (PC), (IV) the combined treatment decreases PC formation presumably due to inhibition of citidylyl transferase activity, (V) CPZ treatment leads to accumulation of labelled phosphatidylinositol (PI) irrespective of the presence or absence of Triton, and (VI) CPZ cannot promote the formation of PI from PA accumulating in response to Triton. The cationic nature of CPZ seems to play specific roles in the inhibition of PPH activity and in the activation of phosphatidyltransferase, both of which direct intermediates toward PI. On the other hand, the amphipathic nature of CPZ and Triton appears sufficient to account for the inhibited DAG-acyltransferase and citidylyl transferase activities.

Chlorpromazine↗

[Thyroid-stimulating hormone-secreting pituitary adenoma].

A 40-year-old male patient with a 2 years history of recurring hyperthyroidism is presented with clinical hyperthyroidism and diffuse goiter. Despite thyreostatic treatment and surgical thyroid ablation the hyperthyroidism recurred. The patient had laboratory evidence of hyperthyroidism and his serum TSH was persistently and enormously elevated (T4:214 nmol/l, T3:6.9 nmol/l, TSH:218 mIU/l)> Computed tomography and magnetic resonance imaging confirmed a pituitary mass of 7 cm in a-p diameter, with supra-, parasellar and sphenoidal extension. The pituitary adenoma was partially resected by transsphenoidal surgery, which failed to result in a substantial decrease in the serum thyrotropin level. Pituitary irradiation and a long-term somatostatin analog octreotide treatment (300-600 micrograms/die) combined with bromocriptine therapy resulted in a significant, but still incomplete suppression of thyrotropin secretion (TSH level about 15 mIU/l) and persisting mild hyperthyroidism. The size of the adenoma was unchanged during the two years of highdose octreotide treatment period. According to our best knowledge this is the first reported case of a thyrotropin-secreting pituitary adenoma in Hungary.

Adult↗