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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 145 records · Page 8Linked to original sources
PubMed1995

Effect of adrenocorticotropic hormone (ACTH) and insulin on the phagocytic capacity of Tetrahymena.

Adrenocorticotropic hormone (ACTH) and insulin negatively influenced the phagocytic activity of Tetrahymena. The two hormones had diverse effects after 4 hr of treatments on no-test-particle containing, "0-cells". At this time the number of "0 cells" was significantly lower in the ACTH-treated groups, while in the insulin-treated groups there was an increase of "0-cells" compared to the control and to the results of the starting experiment. Considering previous results, when small molecular weight hormones, if did at all, positively influenced phagocytosis in Tetrahymena, the experiments call the attention to the differences caused by the size of the signal molecules. In the light of the literary data on hormone effects to phagocytosis in mammals and men, the similarity of the effects in species being very far from each other in evolution, could be concluded.

Adrenocorticotropic Hormone↗
PubMed1995

Effects of G-protein activator fluorides, protein kinase C activator phorbol ester and protein kinase inhibitor on insulin binding and hormonal imprinting of Tetrahymena.

AlCl3, BeCl2 and NaF do not influence the insulin binding of Tetrahymena immediately after treatment, but 24 h later insulin binding is decreased or increased by NaF in a dose-dependent manner, AlCl3 barely influences the binding, and BeCl2 increases it. The effect of all the three fluorides is dose-dependent. While NaF and AlF4 decrease binding at low doses and increase the binding at higher doses, BeF3 increases the insulin binding enormously. NaF does not permit insulin imprinting to be developed, AlF4 inhibits or amplifies the imprinting in a dose-dependent manner, while BeF3 allows imprinting to develop. After 24 h the protein kinase C (PKC) activator phorbol ester (PMA) increases the insulin binding to a similar degree as does the insulin imprinting itself. There was only one dose of the three tested in which PMA inhibited the development of insulin imprinting, whereas the PKC inhibitor reduced insulin binding after 24 h, but could not inhibit insulin imprinting.

Aluminum Compounds↗
PubMed1995

Effects of atrial natriuretic peptide on the unicellular Tetrahymena pyriformis model.

The vertebral hormone, atrial natriuretic peptide (ANP) has characteristic effects in Tetrahymena cells. ANP is able to induce the release of sodium ions, probably via the membrane rather than the contractile vacuole. The hormone is a potent inhibitor of Chinese ink-phagocytosis. A 10(-12) M concentration of ANP has the maximum positive effect on the division of cells but long-term treatments indicate the presence of a down-regulation-like mechanism. ANP has a strong chemoattractant characteristic between 10(-13) and 10(-11) M concentrations. Significant concentration dependent FITC-ANP binding at pretreatments of 10(-12) M suggest the presence of special receptor-dependent mechanisms which are responsible for the development of hormonal imprinting. The similarities between the most effective concentrations (10(-13) - 10(-12) M) and the human serum level of ANP shows that the effects of ANP have a more evolutionary background than previously considered.

Animals↗
PubMed1995

Effect of 3-amino-1-propanol, indomethacin and 4-bromophenacyl bromide on the hormone binding of insulin pretreated Tetrahymena: influence of phospholipid metabolism disturbances on hormonal imprinting.

The compound 3-amino-1-propanol which replaces ethanolamine in phosphatidyl-ethanolamine and inhibits transformation of it, hindered insulin imprinting of Tetrahymena. Indomethacin, an inhibitor of prostaglandin synthesis and arachidonate metabolism provoked negative imprinting. 4-Bromophenacyl bromide, a phospholipase A2 inhibitor, hindered imprintability by insulin. Immediately after treatment these substances inhibited insulin binding. The experiment calls attention to the importance of intactness of metabolic pathways and second messenger systems in the mechanism of imprinting.

Acetophenones↗
PubMed1994

Role of proline in the imprinting developed by dipeptides--in Tetrahymena. Possible role in hormone evolution.

The effects of proline and serine dipeptides containing phenylalanine, alanine and leucine on the behaviour of receptors of Tetrahymena were investigated. Only proline-containing dipeptides were able to develop positive imprinting, and the activity depended on which other amino acid was present in the dipeptide. In contrast to the positive imprinting effect of the dipeptides Pro-Phe and Pro-Ala, the dipeptide Pro-Pro and Pro-Leu caused negative imprinting. Serine dipeptides produced negative imprinting in all cases. The possible importance of proline in the evolution of hormone specificity is discussed.

Animals↗
PubMed1994

A calcium-dependent protein kinase is present in tetrahymena.

A Ca(2+)-dependent protein kinase of Tetrahymena thermophila has been partially purified and characterized. The molecular mass of the enzyme is less than that of similar enzymes (for example protein kinase C), being about 55 kDa. After purification and in the presence of Ca2+ the enzyme activity increased. The promoter of protein kinase C (PKC) activity, phorbol myristate acetate (PMA), increased the activity while the protein kinase inhibitor H-7 decreased the activity of the enzyme. The experiments demonstrate the presence, activity and similarity to vertebrate enzymes of a protein kinase at a low level of phylogeny.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Chemotactic response of unicellular Tetrahymena to a leukocyte attractant peptide and its repellent derivative: evolutionary conclusions.

Chemotactic properties of the leukocyte chemoattractant N-formyl-Norleucine-Leucine-Phenylalanine (NLP) and its antagonist N-t-BOC-Norleucine-Leucine-Phenylalanine (BOC-NLP) were investigated in unicellular Tetrahymena pyriformis cells. NLP express its attractant character in a two-peak profile of concentration course (maximum at 10(-8)-10(-7) M and 10(-11) M) while BOC-NLP has a constant repellent character (maximum at 10(-12) M). The observed homology of action concurs with our theory about the wide evolutionary background of signal molecules and receptors.

Animals↗
PubMed1994

Insulin pretreatment (imprinting) produces elevated capacity in the insulin binding of Tetrahymena. Different binding by the cilia of the body and oral field.

Gold-labeled insulin is bound first of all to the cilia of the oral field of Tetrahymena. A primary treatment (hormonal imprinting) with insulin increases the binding capacity even after 24h and makes it more sensitive for appearance a week later, within a minute of giving insulin-gold. The food vacuoles contain insulin-gold in pretreated cells or without pretreatment as well, though in imprinted situations the label can be found in pinocytotic vesicles at the bases of cilia in the oral field. Altogether, a functional difference can be observed between the cilia of the oral and non-oral surfaces of Tetrahymena and hormonal imprinting has a specifying effect on the binding of labeled hormone.

Animals↗
PubMed1994

Effect of insulin on the incorporation of 3H-inositol into the inositol phospholipids (PI, PIP, PIP2) and glycosyl-phosphatidylinositols (GPIs) of tetrahymena pyriformis.

The unicellular tetrahymena contains inositol phospholipids (PI, PIP, PIP2) and GPIs. Treatment with 10(-5) M insulin decreases the total 3H-inositol incorporation and incorporation into PI. 24 h after 10(-6) M insulin treatment there is an elevation of these parameters. Second treatment with 10(-6) M insulin doubles and 10(-5) M decreases these levels. This means that the effect on phosphoinositide turnover by insulin in Tetrahymena is rather concentration dependent. Inositol incorporation into GPIs is also influenced by insulin.

Animals↗
PubMed1994

Immunocytochemical verification of the insulin receptor's specificity in the nuclear envelope of Tetrahymena. Comparison with receptors of the plasma membrane.

The unicellular Tetrahymena possess hormone receptors in the nuclear envelope similarly to higher rank animals. These receptors bind insulin and their specificity is detectable by monoclonal antibodies developed to insulin. The hormonal (insulin) pretreatment (imprinting) of the cell did not alter the binding capacity of the nuclear membrane, demonstrated by antibody-technique. The specific binding characteristics of the plasma membrane was demonstrated and this was significantly increased following imprinting. In the nucleus of Tetrahymena presence of insulin was not detected by immunocytochemical method.

Animals↗
PubMed1994

Influence of insulin on the movement of Tetrahymena pyriformis. Hormonal imprinting alters the velocity.

Treatment with insulin, cyclic adenosine monophosphate (cAMP) or theophylline, which uniformly influence the intracellular cAMP level, accounted for appreciable changes in the movement of Tetrahymena pyriformis. All applied treatments caused a quantitative decrease in the percentage of relatively rapid movements (straight and spiral swimming) and a proportional increase in that of slow movements (standing, turn, creeping). A single treatment with insulin caused a quantitative decrease in fast movements and a quantitative increase in slow movements also in the offspring generations and reexposure to insulin had a similar, but even stronger effect.

Animals↗
PubMed1994

Breastmilk can mediate chemical imprinting. Benzpyrene exposure during lactation reduces the thymic glucocorticoid receptor density of the offspring.

1. Prolonged benzpyrene treatment during lactation reduced the number of glucocorticoid receptors of offspring in adulthood significantly without altering the receptor affinity. 2. Dexamethasone treatment identical to benzpyrene exposure had no effect either on receptor number or affinity. 3. The results of the present investigations draw attention to the possible way of receptor alteration via breastmilk.

Animals↗
PubMed1994

Benzpyrene treatment in adulthood increases the testosterone level in neonatally steroid(allylestrenol)-treated male rats.

1. Serum testosterone level was significantly elevated in adult male rats after a single perinatal allylestrenol administration. 2. Benzpyrene treatment of adult rats perinatally treated with allylestrenol, did not cause changes 1 week after benzpyrene treatment, but 3 weeks later an extremely high serum testosterone level was found. 3. In control animals benzpyrene administration in adulthood did not influence the serum testosterone level either 1 or 3 weeks following the treatment.

Allylestrenol↗
PubMed1994

Effect of treatment with contraceptive steroids on the sexual behaviour of rats pretreated with benzpyrene or allylestrenol in fetal or neonatal age.

Treatments with contraceptive steroids significantly reduced the receptivity of adult female rats. This effect was not observed in ovariectomized females treated with high doses of estrogen and gestagen hormones prior to the investigation. The receptivity was also significantly reduced in rats treated with steroids (allylestrenol or benzpyrene) in their fetal or neonatal age, as it was demonstrated in previous experiments. The contraceptive treatment of the above described, pretreated adults resulted in improved function of receptivity, but it had no difference compared to the group which was only treated with anticoncipient. This means that neonatal treatment with allylestrenol or benzpyrene does not influence the effects of contraceptive steroids on the sexual behaviour (receptivity). The two effects are not additive.

Allylestrenol↗
PubMed1994

Effect of permanent starvation on the insulin receptors of the nuclear envelope of Tetrahymena.

Insulin receptors of Tetrahymena following a two-hour starvation (one cell generation) can bind the insulin similarly to the fed, control cells. The nuclear envelope of Tetrahymena cells which have already met the hormone (imprinted cells) can bind the insulin significantly stronger than the control. This binding capacity has a mild decrease after a two-hour starvation; after 18-hour starvation the decreasing effect is more expressed and reaches the control level. On the ground of the experiments it is probable that the insulin receptors of the plasma membrane and the nuclear envelope are identical.

Animals↗
PubMed1994

Change in insulin binding capacity of plasma membrane and nuclear envelope of Tetrahymena following a single long-term pretreatment and several short-term pretreatments (imprinting) with insulin.

Following insulin pretreatment (hormonal imprinting) of Tetrahymena cells there was an increased binding of insulin both in the plasma membrane and in the nuclear envelope of the offspring generations. A short (1 x 15 min) treatment did not produce imprinting in the plasma membrane but a 1 h treatment was sufficient. A similar short (1 x 15 min) treatment was enough to develop imprinting in the nuclear envelope and this is the treatment which induced the highest response. In the nuclear membrane there was a significant difference in the effect of 4 x 15 min and 1 x 60 min treatments but there was no effect in the plasma membrane. The effect of imprinting was observed after 48 h (16-20 generations). The repeated treatment of imprinted cells did not induce a further increase in the binding of the hormone.

Animals↗
PubMed1994

Tetrahymena cells distinguish insulin preparations according to either their amorphous and crystalline form or their bovine and porcine origin: aspects of hormone binding and chemotaxis in relation to imprinting.

Bovine insulin had a strong negative effect on the chemotaxis of Tetrahymena at the first encounter with the hormone. The crystalline porcine insulin proved to be neutral, while the amorphous porcine insulin had a significant positive chemotactic effect. At the second encounter with the hormone the presence of imprinting was detectable with bovine insulin and induced a significant positive chemotaxis. The chemotactic effect of amorphous porcine insulin was depressed while crystalline porcine insulin expressed the most significant positive chemotactic effect. In the binding of hormones there was unambiguous positive imprinting independently from the species specificity and from the physicochemical condition of the insulins. Tetrahymena discriminated at both the first and second encounters between the bovine and porcine insulins which differed in two amino acids. The imprinter capacity evident in binding was independent of the chemotactic preference and the imprinting embodied in chemotaxis.

Animals↗