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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 109 records · Page 6Linked to original sources
PubMed1997

Indomethacin alters phospholipid and arachidonate metabolism in Tetrahymena pyriformis.

Indomethacin an inhibitor of the cyclooxygenase pathway for arachidonate metabolism in vertebrates, totally inhibited 32P incorporation into phospholipids at a dose of 2.0 or 5.0 mM in Tetrahymena. Treatment with 0.1 mM indomethacin caused higher arachidonic acid (AA) incorporation into phosphatidylinositol (PI) and lower incorporation into phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylinositol (4,5) bisphosphate (PIP2). The same treatments in the presence of 3H-AA resulted in a significantly elevated 3H-diacylglycerol (DAG) level and free AA level compared with control cells. Indomethacin influences the lipid cycle and therefore the inositol phosphate cycle in Tetrahymena.

Animals↗
PubMed1997

PLA2 activity in Tetrahymena pyriformis. Effects of inhibitors and stimulators.

Phospholipase A2 (PLA2) is an enzyme which participates in signalling mechanisms cleaving arachidonate from sn-2 position of glycerophospholipids. In this study we have verified the existence of a PLA2-like activity in the free living protozoan, Tetrahymena pyriformis GL. This activity is Ca(2+)-independent, EDTA (10 mM) has no effect on its activity. Quinacrine (0.1 mM) and 4-bromophenacyl bromide (BPB; 0.1 mM) inhibited, melittin (20 micrograms/ml) significantly stimulated the PLA2 activity and the release of free arachidonic acid (AA) from 1-acyl 2-14C-arachidonyl-3-phosphatidylethanolamine substrate. Melittin stimulated PLA2 hyperactivity is CA(2+)-dependent. There was no considerable alteration in the PLA2 activity by stimulation of the activity by tyrosine kinase (with vanadate, H2O2), phospholipase C (PLC) (with phorbol 12, 13-dibutyrate) or G-proteins (with NaF, AlF4), thus in Tetrahymena PLA2 activity seems to be independent of these--in Tetrahymena (also functioning)--signalling pathways. Treatment with quinacrine and BPB leads to decreased synthesis and disturbed breakdown of phospholipids and phosphoinositides. These findings suggest that PLA2 activity is in connection with the phospholipid metabolism of Tetrahymena.

Acetophenones↗
PubMed1997

Mitochondrial dehydrogenases in different taxa of tetrahymena: effect of insulin.

Mitochondrial dehydrogenase activity was measured in seven taxa of Tetrahymena (T. pyriformis G1. T. hegewishi, T. malaccensis, T. pigmentosa, T. shapiro, T. thermophila CU-399, T. thermophila MS-1). Enzyme activity was different in the taxa investigated. Insulin reduced enzyme activity in six of the seven taxa studied. The duration of activity reduction was relatively long (5-10 min.) in most of the cases, and in T. hegewishi this lasted up to the end of the measurements (30 min.). There was no interrelation between the basic dehydrogenase activity of the taxon and the effect of insulin. There was also no correlation between the degree of relationship (of the taxa) and the dehydrogenase profile after insulin treatment.

Animals↗
PubMed1997

Imprinting effects of proline containing dipeptides (proline-glycine, proline-leucine, proline-valine and their retro variants) in tetrahymena. Evolutionary conclusions.

Proline-glycine, proline-leucine and proline-valine dipeptides and their retro variants were used in the experiments to study the effects of pretreatment (imprinting) in Tetrahymena, by investigating fluorescein isothiocyanate (FITC)-conjugated peptide binding. The protozoan organism could differentiate between the proline-dipeptides containing different partner amino-acids and between the dipeptides having the amino acids in reversed positions. The effect of imprinting was positive or negative and this was dependent on the type of the partner amino acid and on its position. Pro-Gly and Pro-Leu induced positive imprinting (elevated FITC-dipeptide binding) and Pro-Val induced negative imprinting (decrease of FITC-peptide binding). There was positive imprinting induction in two cases for the retro FITC-peptide and in one case for the FITC-conjugate of the imprinter peptide itself. The highest positive imprinting (almost 60% increase) was induced by Pro-Gly for FITC-Gly-Pro. Considering earlier--chemotaxis--experiments, the results of the present--binding--studies run parallel with the physiological effects. The experiments call attention to the sharp differentiating ability of small peptides at a unicellular level, that could have some role in the selection of molecules for hormone formation, during evolution.

Animals↗
PubMed1997

Effect of perinatal vitamin A or retinoic acid treatment (hormonal imprinting) on the sexual behavior of adult rats.

Single neonatal treatment with vitamin A (retinol) dramatically reduced the sexual activity of adult male rats. In females there was a significant decrease in the Meyerson index and a non significant decrease in the lordosis quotient. The effect of three perinatal treatments (at the first, third and fifth day) with all-trans retinoic acid was much weaker, causing only a significant increase in the time of the first ejaculation in males and non-significant decrease in the lordosis quotient of females. The experiments call attention to the false imprinting provoking effect of materials acting on members of the steroid receptor superfamily with possible human health aspect.

Animals↗
PubMed1997

Transgenerational effect of a single neonatal benzpyrene treatment (imprinting) on the sexual behavior of adult female rats.

Male and female rats were neonatally treated with a single dose of benzpyrene. The adult animals were mated inter se, forming control-control, benzpyrene (female)-control, benzpyrene (male)-control, and benzpyrene-benzpyrene treated couples. In the F1 and F2 generations (without any further treatment) the females's sexual behavior was tested to Meyerson index and lordosis quotient after ovariectomy and hormone treatment, using experienced males. In the F1 generation both indices were significantly reduced in the maternally treated, paternally untreated groups, however this reduction was not present in the group where the treatment was maternal and paternal alike. In the F2 generation, beside the more expressed reduction in the grandmaternally treated group, a moderate reduction in the sexual activity of progenies having treated grandfather or two treated grandparents were observed. The experiment call attention to the transgenerational sexual behavioral effect of a dangerous environment pollutant, benzpyrene.

Animals↗
PubMed1997

Effects of the amino sugars, glucosamine, mannosamine, or the fluorinated derivative 2-deoxy-fluoroglucose on the phosphatidyl inositol and glycosyl phosphatidyl inositol systems of Tetrahymena.

Sugar derivatives which have an inhibitory effect on glycosyl phosphatidyl inositol (GPI) synthesis in mammals, primarily prevented 32P incorporation in the unicellular Tetrahymena. Incorporation of 3H-mannose and 3H-inositol was induced by mannosamine. While there was a uniform effect of sugar analogues in mammals, they could not elicit totally similar effects in Tetrahymena. Analogues of sugar also affected synthesis in the phosphatidyl inositol (PI) system. Synthesis of GPI in Tetrahymena was different from that in mammals, but the metabolism of GPI and PI revealed similarities.

Animals↗
PubMed1997

Accumulation of insulin-gold particles in the oral apparatus of Tetrahymena after insulin pretreatment (imprinting).

The oral apparatus and body ciliature of untreated control cells bind insulin-gold very rarely. From 1 day to 1 week after insulin pretreatment (hormonal imprinting) an enormous quantity of insulin-gold was bound by the oral cilia, completely filling the region, while the insulin-gold on the body ciliature is scattered. The binding was specific for insulin, since polyethylene glycol (PEG)-gold was not bound at all. The results call attention to the binding and the increasing role of hormonal (insulin) imprinting, and particularly to the marked role of the oral region in this binding. The roles of mucocyst extrusion and specific binding by receptors are discussed.

Animals↗
PubMed1996

Investigations of receptor-mediated phagocytosis by hormone-induced (imprinted) Tetrahymena pyriformis.

Receptor-mediated endocytosis by Tetrahvmena pyriformis was studied using tetramethylrhodamine isothiocyanate-labeled concanavalin A (TRITC-Con A) with fluorescence and confocal microscopy. In the presence of insulin, or 24 h after insulin pretreatment (hormonal imprinting), the binding and uptake of TRITC-Con A increased when compared to controls, owing to the binding of TRITC-Con A to sugar oligomers of insulin receptors. Mannose inhibited the binding of Con A, thus demonstrating the specificity of binding. Histamine, a phagocytosis-promoting factor in mammals and Tetrahymena, and galactose, did not influence the uptake of TRITC-Con A.

Animals↗
PubMed1996

Effect of insulin on the phospholipase-D activity of untreated and insulin-pretreated (hormonally imprinted) Tetrahymena.

Insulin treatment of the unicellular Tetrahymena enormously increases the activity of phospholipase D (PLD) within 30 min. Insulin pretreatment (hormonal imprinting) does not influence basal PLD activity after 24 h. The second insulin treatment failed to stimulate PLD activity in insulin imprinted Tetrahymena. The results suggest the presence of the functional PLD activity in Tetrahymena and that hormonal imprinting modifies signal transduction to PLD, as previously reported in calmodulin activation and phophatidylinositol 4,5-bis-phosphate (PIP2) synthesis.

Animals↗
PubMed1996

Imprinting effects of three amino acids (alanine, lysine and glycine) and their oligopeptides in Tetrahymena pyriformis. Data from the hormone and hormone receptor evolution.

Hormonal imprinting takes place at the first encounter of the hormone and receptor, and results in a changed binding capacity and reaction of the cell and its progeny generations. The imprinting effect of three amino acids and their oligopeptides is studied using fluorescent-labelled peptides. Glycine and lysine could provoke positive imprinting (increased binding in the progeny generations) for their own peptides, but alanine could not. Mostly positive imprinting was provoked by glycine and lysine peptides for their own peptides of different chain length. The optimal chain length provoking self-imprinting was four for glycine, two for lysine and three for alanine. Except in this case, alanine was neutral or provoked mostly negative imprinting. After reaching the optimal chain length, there is a decline in binding. Evolutionary conclusions are discussed.

Alanine↗
PubMed1996

Chemotaxis of the unicellular green alga Dunaliella salina and the ciliated Tetrahymena pyriformis--effects of glycine, lysine, and alanine, and their oligopeptides.

Chemotactic properties of amino acids (L-alanine, glycine and L-lysine) and their oligopeptides (10(-6) M) and binding sites to these ligands were investigated in two unicellular models, the heterotrophic Tetrahymena pyriformis and the auxotrophic Dunaliella salina. Chemotaxis of Dunaliella induced by simple amino acids and their derivatives demonstrated that binding sites (receptors) for food molecules are not only present in the membrane but are also able to induce their basic physiological response. In Tetrahymena, substances with special molecular structure and properties (polar, hydrophilic character of the signal peptide chain)-5-L-Lys, 5-Gly- were required for chemoattraction, other peptides tested, lacking the required structure, were repellent. Divergences in chemotaxis and binding assays of both species suggest that trends of functional and binding parameters do not run parallel at this level of evolution.

Alanine↗
PubMed1996

Effect of neonatal allylestrenol treatment and adult benzpyrene treatment on rat thymus glucocorticoid receptors.

1. Neonatal treatment with allylestrenol caused an increase in the number of glucocorticoid receptors in the thymus in the adult. 2. Benzpyrene treatment of adult animals persistently reduced the glucocorticoid receptor number in rats that were not submitted to neonatal treatment. This effect was not observed in adult animals following neonatal treatment with allylestrenol. 3. The experiment calls attention to the permanent effect of steroid imprinting and to the developmental stage dependence of the direction of imprinting. 4. The effect of neonatal steroid treatment on a later steroid influence is also demonstrated.

Allylestrenol↗
PubMed1996

Contraceptive treatment increases the affinity of uterine estrogen receptor in adult rat: perinatal gestagen treatment changes the reaction.

Uterus estrogen receptor affinity increases in adult rats if treated with contraceptive, without receptor density change. Uterus estrogen receptor density decreases in adulthood following allylestrenol (Gestanon) treatment perinatally with receptor affinity unchanging. In perinatally allylestrenol treated rats contraceptive treatment resulted in the decrease of receptor affinity and increase of density, related to the only perinatally allylestrenol treated animals. The results draw attention to the fact that contraceptives may influence the estrogen receptor state of the uterus and the pregnancy maintaining treatment (by allylestrenol) may influence the state of uterine estrogen receptors for life via the later effect of contraceptives commonly dosed.

Allylestrenol↗
PubMed1996

Changes in sexual behavior of adult male and female rats neonatally treated with vitamin D3.

1. Neonatal treatment of rats with vitamin D3 resulted in a change of sexual behavior in adulthood. 2. 2.5 mg vitamin D3 completely inhibited the ejaculation of males without any apparent influence on sexual desire. 250 mg vitamin D3 influenced both the desire and ejaculation. 3. Sexual activity of females was depressed by both doses. 4. The experiments demonstrate that vitamin D3, a steroid in structure, given in the critical period of hormonal imprinting may influence steroid hormone-receptor commanded events for life, in a way similar to the effects exhibited by synthetic steroid hormone analogues and benzpyrene in earlier studies.

Analysis of Variance↗
PubMed1996

The relationship of the endoplasmic reticulum to the Golgi complex in Tetrahymena pyriformis.

The endoplasmic reticulum (ER) and the closely connected, single dictyosomal Golgi apparatus of Tetrahymena pyriformis cells showed random distribution in the cytoplasm. Ribosomes were evident, and coated vesicles pinched off from the ER were seen. The membranes of the endoplasmic reticulum generally formed a tube-like structure, although after histamine treatment multiple, folded and circular structures were observed. The number of coated vesicles detaching from the endoplasmic reticulum increased as a result of histamine treatment.

Animals↗
PubMed1996

Different and selective chemotactic responses of Tetrahymena pyriformis to two families of signal molecules: lectins and peptide hormones.

Tetrahymena chemotactically responds to the presence of different signal molecules. The response elicited is different to peptide hormones and to lectins however the cell distinguishes the individual members of the two groups. The negative chemotactic effect is characteristic of the hormones tested and it is especially true for oxytocin and vasopressin, however Tetrahymena distinguishes also these two hormones. While the effect of hormones was mainly independent to the concentration tested, lectins elicit an increasing chemoattractant effect above 10(-9) M concentration. Below 10(-9) M the sugar specific, receptor level effect of lectins is probable. The experiments draw attention to the perceptional selectivity of Tetrahymena embodied in chemotaxis.

Animals↗