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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
PubMed1995

Effects of L-alanine and L-alanine peptides on the chemotaxis of tetrahymena: evolutionary conclusions.

L-alanine and its peptides (L-Ala-2-6) do not attract or repulse Tetrahymena in a 10(-8) M concentration. In 10(-10) M concentration there is a consistent repellent effect. Twenty four hours after L-alanine or L-alanine-peptides' pretreatment (imprinting) the progeny generation of the cells react differently to the same materials. L-Alanine, L-alanine penta- and hexapeptide in both concentrations are chemoattractant, while L-alanine tetrapeptide is repellent. L-Alanine dipeptide is inert in 10(-10) M and repellent at 10(-8) M concentrations, while L-alanine tripeptide is strongly repellent at 10(-10) M and attractant at 10(-8) M concentrations. This means, that the first encounter (imprinting) with an exogenous amino acid or peptide is decisive to the later reaction of the protozoan cell. The chain length is important in the imprinting, however the reaction is not consistent. The experiments call the attention to the significance of imprinting in the receptor and hormone evolution.

Alanine↗
PubMed1995

Hormonal imprinting: neonatal treatment of rats with the peroxysome proliferator clofibrate irreversibly affects sexual behaviour.

In the rat, the peroxysome proliferator activated receptor (PPAR) inducer clofibrate can moderately influence the hormone (testosterone) level and, after single perinatal treatment, irreversibly affects sexual behavior through the mechanism of hormonal imprinting. The thymic glucocorticoid and estrogen receptors weren't significantly influenced. The experiments call the attention to the universality of false imprinting by molecules able to bind to the steroid/thyroid receptor superfamily, and point to the different sensitivity to different ligands.

Animals↗
PubMed1995

Effect of prenatal allylestrenol treatment (hormonal imprinting) on the serum testosterone and progesterone level in adult rats.

1. Female rats were treated with allylestrenol on the 15th, 17th and 19th days of their pregnancy. 2. Serum testosterone and progesterone level of their three months old offspring were higher than control in males and females, respectively. 3. Serum progesterone levels of females, treated both prenatally and in adulthood, does not differ from control values. Serum testosterone level of males, treated prenatally and in adulthood, is lower than control. 4. One single allylestrenol treatment in adulthood does not make changes in testosterone concentration in males, but progesterone level is elevated in females. 5. Our experiments draw attention to the dangers of prenatal allylestrenol treatments (administered in case of endangered pregnancies) which may have long lasting effects on sexual steroid hormone levels.

Aging↗
PubMed1995

Effect of nifedipine treatment (imprinting) of rat feti and newborns on the responsiveness of adult rat's uterus. Extension of the imprinting theory.

1. The uterus of adult progeny of rats treated with nifedipine during the late phase of pregnancy react in vitro to oxytocin less and the contractility of ones treated with higher dose (100 micrograms) disappears. 2. There is a more pronounced deficiency or lack of responsiveness in five week old animals treated with nifedipine neonatally. 3. The experiments demonstrate that perinatal imprinting can be developed not only on hormone receptors and enzymes but on ion (Ca2+) channels of the plasma membrane. Consideration of this fact might have an importance in clinical aspects too.

Animals↗
PubMed1995

Effects of the mammalian vasoconstrictor peptide, endothelin-1, on Tetrahymena pyriformis GL, and the immunocytological detection of endogenous endothelin-like activity.

The vasoconstrictor endothelin-1 (ET-1) is shown to have significant physiological effects on a unicellular organism, Tetrahymena pyriformis. These responses include: (1) A significant increase in intracellular [Ca2+] induced by 10(-10) M ET-1; (2) Increased chemotaxis, maximal at 10(-10) M; and (3) A small inhibition of proliferation at the 10(-13)-10(-12) M concentration range. Immunocytochemical detection of endogenous ET-1 using rabbit antibodies directed against human or porcine ET-1 indicates that this is a further example of the widening group of vertebrate hormones now known to be synthesized by Tetrahymena. These observations suggest that hormones are of considerable antiquity in their phylogenetic appearance and have been highly conserved throughout evolution.

Animals↗
PubMed1995

Pubertal benzpyrene exposition decreases durably the sexual activity of the adult male and female rats.

Single benzpyrene treatment of 5 week old male and female rats significantly decreased their sexual activity at 3 months of age. Among the hormone preparations used nandrolone was comparatively practically ineffective, while estradiol decreased the lordosis quotient of females. In males benzpyrene produced a total failure of ejaculation. These results draw attention to the wide time-scale of receptorine and behavioral effects of the aromatic hydrocarbon, benzpyrene. These effects are detectable following fetal, neonatal or pubertal treatments, especially in females. In males, the negative effect was manifested after neonatal and pubertal treatments only. The experiments suggest that in some cases hormonal imprinting does not develop solely in the perinatal period but it might develop later.

Anabolic Agents↗
PubMed1995

Effect of neonatal allylestrenol treatment (hormonal imprinting) on the serum testosterone and progesterone concentration in adult rat.

Serum testosterone concentration was significantly elevated in adult male rats by a single perinatal allylestrenol administration. One week after a second allylestrenol treatment in adulthood the hormone concentration dropped below the control values. Serum progesterone concentration was significantly lowered in adult female rats by a single perinatal allylestrenol administration. Following a second allylestrenol treatment in adulthood the hormone concentration reached the control values. These experiments demonstrate that the hormonal imprinting caused by allylestrenol (a steroid used in the treatment of endangered pregnancy) not only acts at receptor level and produces changes in sexual behaviour, but also induces modifications in serum hormone concentrations.

Aging↗
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↗