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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1995

Effect of phorbol 12-myristate 13-acetate (PMA) on the phosphoinositol (PI) system in Tetrahymena. Study of the 32P incorporation and breakdown of phospholipids.

Phorbol 12-myristate 13-acetate (PMA) treatment elicited an increased 32P incorporation into phospholipids namely phosphatidyl-inositol (PI); phosphatidyl-inositol-4-phosphate (PIP); phosphatidyl-inositol-4,5-bis-phosphate (PIP2); phosphatidyl-acid (PA); phosphatidyl-choline (PC) and phosphatidyl-ethanolamine (PE) particularly at the 20-30th min after treatment. The ratio of members of the phosphoinositol system, especially PIP and PI, related to the total phospholipid content was increased. PMA (2 x 10(-7) M) was the most effective of the three concentrations tested. The results call attention to the presence of a working phosphoinositol system in Protozoa.

Animals↗
PubMed1995

A confocal microscopic evaluation of the effects of insulin imprinting on the binding of Concanavalin A by Tetrahymena Pyriformis.

With confocal microscopy it is possible to study the Concanavalin A (Con A) binding characteristics of the surface and interior of a single cell by viewing optical sections. It was observed in Tetrahymena pyriformis that Con A bound both to the plasma membrane and to intracellular structures. Incubation of cells with a competing sugar a-methylmannopyranoside, decreased binding. Hormonal imprinting with insulin resulted in an increase in binding of Con A to the cell surface and a decrease in intracellular binding. It is possible that the intracellular binding sites may migrate to the plasma membrane.

Animals↗
PubMed1995

Insulin treatment (hormonal imprinting) increases the insulin production of the unicellular tetrahymena long term. Is there a simultaneous formation of hormone receptor and hormone?

Insulin treatment of Tetrahymena pyriformis resulted in a long-lasting increase in the insulin content of the cells. After about 200 generations, insulin levels significantly higher than in the control were demonstrated by using a quantitative immunocytochemical method. Although the insulin content fluctuated from day to day, it was always higher in the insulin pre-treated (imprinted) cells than in the controls. The results emphasise the simultaneous stimulation of hormone and receptor formation by hormonal imprinting.

Animals↗
PubMed1995

Human cytokines interleukin (IL)-3 and IL-6 affect the growth and insulin binding of the unicellular organism Tetrahymena.

Interleukin (IL)-3 and IL-6 significantly increase the growth rate of the unicellular organism, Tetrahymena. The effect elicited by IL-3 is long lasting as it was also detectable after 20 generations. Effect of IL-6 was detectable as long as the substance was present in the cell culture. Pretreatment with IL-3 did not enhance the proliferative response to subsequent IL-3 treatment, but the second exposure to IL-3 considerably depressed the active proliferation of Tetrahymena cells. However, a positive 'priming effect' elicited by IL-6 resulted in an increased growth rate following repeated IL-6 stimulation. Insulin binding to the plasma membrane of Tetrahymena was increased by IL-6 but not by IL-3 after 24 hours, and this enhancement appeared even after one hour incubation. If the cells were pretreated with insulin, IL-6 did not influence insulin binding, while an inhibition by IL-3 was observed. These results direct attention to the similarities of actions induced by IL-3 and IL-6 at different levels of phylogeny probably due to the presence of cytokine receptor-like structures on this unicellular organism.

Animals↗
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↗