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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1996

Effect of neomycin on glycosyl-phosphatidylinositol and phosphatidylinositol system of Tetrahymena.

Neomycin does not inhibit but increases the incorporation of 32P into phosphatidylinositols of Tetrahymena. This elevation is due to neomycin inhibition on the turnover of the phosphatidylinositol (PI) system. Neomycin also prevents the synthesis of glycosyl-phosphatidylinositol (GPI). These experiments draw attention to the inhibitory effect of neomycin both on GPI synthesis and PI turnover, and the connection between these systems. An explanation for the inhibitory effect of neomycin on hormonal imprinting is discussed.

Animals↗
PubMed1996

Effect of perinatal triiodothyronine (T3) treatment on thymic glucocorticoid and estrogen receptors and uterus estrogen receptors. Receptor selectivity during hormonal imprinting.

Triiodothyronine (T3) treatment at 1, 3 and 5 days after birth significantly increased the binding capacity (density) of the thymus glucocorticoid receptor of male and female rats in adult age. There was no change in the binding capacity of uterine and thymic estrogen receptors. The experiments point to the sensitivity of developing hormone receptors and call the attention to the possibility of overlap between the members of the steroid receptor superfamily at the perinatal critical period. This overlap is not dependent on the structure of the hormone, however it is dependent on the structure of receptors and acceptors. The difference in the reaction of glucocorticoid and estrogen receptors shows the differences in the sensitivity of receptors to false imprinting.

Animals↗
PubMed1996

Effect of neonatal treatment with monoclonal antibody to thyrotropin (TSH) receptor on the thyroxin (T4) level and certain parameters of the internal genital organs of adult rats.

Treatment of newborn rats with a single dose of monoclonal antibody to TSH receptor, caused permanent changes in the body weight, T4 level, and different sexual parameters. There are considerable sex and organ dependent differences in the sensitivity. Body weight and physical condition of males deteriorates, while the condition of the females is constant. However, T4 level of females significantly increases while that of the males does not change. The weight of seminal vesicle increases, while ovarian weight decreases. Effect of hCG treatment in adult age is inhibited by neonatal antibody (to TSH receptor) treatment. The experiment calls the attention to the imprinter effect of antibodies in the neonatal critical period, which effect could be manifested on the antibody's own (provoked) or foreign (related) receptor.

Animals↗
PubMed1996

Benzpyrene treatment decreases the sexual activity of adult rats, what is reversed in neonatally allylestrenol treated animals.

In neonatally allylestrenol treated animals in adult age a single benzpyrene treatment significantly decreases the female and significantly increases the male rat's sexual activity. Three month old females display the negative sexual behavioral effect of neonatal allylestrenol treatment less than the six month old ones. The benzpyrene treatment in adult age decreases the sexual activity of male rats. The experiments call the attention to the modifying effect of perinatal steroid treatments to similar exposure in adult age.

Aging↗
PubMed1996

Effects of local anaesthetics and phenothiazines on 32P-incorporation into the inositol phospholipids and glycosyl phosphatidylinositol of Tetrahymena pyriformis GL.

In Tetrahymena local anaesthetics significantly decreased, while phenothiazines completely inhibited, the uptake of 32P into inositol phospholipids. Glycosyl phosphatidylinositol (GPl) synthesis was also reduced by phenothiazines, in contrast to local anaesthetics which significantly increased the GPl synthesis. The results present interpretation of prior observations that inositol phospholipids and GPl in the unicellular Tetrahymena play an essential role in signal transduction similar to the cells of multicellular organisms. Hormonal imprinting does not develop in the presence of phenothiazines or local anaesthetics in Tetrahymena.

Anesthetics, Local↗
PubMed1995

Long-lasting persistence of elevated sister-chromatid exchange frequencies induced by perinatal benzo(a)pyrene treatment in rat bone-marrow cells.

In this work the possibility that a mutagenic factor acting in utero or in the perinatal period might lead to elevated mutagenic rates in bone-marrow cells after a considerable period of time was examined. An aromatic hydrocarbon, benzo(a)pyrene was used as the test substance. Benzo(a)pyrene treatments resulted in significantly higher sister-chromatid exchange (SCE)-frequencies in both fetal and neonatal groups in both sexes, even four months after exposure. In a second experiment we examined whether mutagenic exposure suffered in utero could make the individual more susceptible to mutagenic effects in adulthood. Preliminary results indicate that such a possibility could exist.

Animals↗
PubMed1995

Effects of choline and ethanolamine on the synthesis and breakdown of the inositol phospholipid (PI) system in Tetrahymena.

Lower concentrations of choline chloride and ethanolamine (10(-3) M; 10(-5) M) increased phosphatidyl inositol (PI), phosphatidyl inositol monophosphate (PIP) and phosphatidyl inositol bisphosphate (PIP2) level of Tetrahymena, while higher concentrations (10(-2) M) decreased them. These two substances also influenced, however in a less obvious way, the transformation of inositol phospholipids. The experiments draw attention to the sensitivity of the precursors of the second messenger system at a phylogenetically low level.

Animals↗