Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 145 records · Page 8Linked to original sources

PubMed1993

Presence in and effects of pineal indoleamines at very low level of phylogeny.

The unicellular organism Tetrahymena contains serotonin and is able to take up the hormone from its milieu. The serotonin content of the cell changes as a function of the presence of foreign exogenous hormones. This indicates a possible role of serotonin as a chemical mediator. Exogenous serotonin stimulates the RNA synthesis of Tetrahymena, and it was the only one among the hormones studied which kept the RNA level durably high. Serotonin stimulates phagocytosis and growth of Tetrahymena, and its precursors also stimulate growth. Serotonin can imprint Tetrahymena, and as a consequence of this the effect of the hormone increases in the case of further encounters. Treatment with serotonin-related molecules soon after imprinting can reduce the effect of imprinting. Melatonin can contract the pigment cells of Planaria; however, its precursors serotonin and tryptamine can do this more intensely. Both melatonin and serotonin can influence the regeneration of Planaria, with effects which differ when different phenomena are studied. Evolutionary theories are discussed.

Animals↗

PubMed1993

The effect of epinephrine on the intracellular free calcium of parent and Ki-ras-transfected NIH3T3 cells.

Here we describe differences in the formation of the epinephrine-induced Ca2+ transients between parent and Ki-ras-transformed NIH3T3 fibroblasts. These transients proved to be the results of an efflux from both the thapsigargin-sensitive and -insensitive intracellular pools. While the epinephrine-induced detachment of the ras-transformed cells might be due to cytoskeletal and/or cell-matrix alterations.

3T3 Cells↗

PubMed1993

The binding of diazepam in the mitochondria of Tetrahymena pyriformis as detected by quantitative high resolution autoradiography.

Tritiated diazepam accumulates mainly in the mitochondria of the unicellular Tetrahymena. This is the case in both a single (the first encounter) and a repeated (one day or a week after the first) administration of the drug. When imprinting of Tetrahymena by diazepam (the first encounter) is followed a week later by the administration of the labelled drug, the membranes of the vesicles, too, show the appearance of label. Regarding the studies presented here, the unicellular Tetrahymena also contain diazepam receptors in the mitochondria as suggested for cells of higher rank animals.

Animals↗

PubMed1993

Anabolic steroid (nandrolone) treatment during adolescence decreases the number of glucocorticoid and estrogen receptors in adult female rats.

The density of thymic glucocorticoid receptors and the density of uterus estrogen receptors (I) decreased significantly in adult female Wistar rats following nandrolone treatment at the age of six and seven weeks. There was no significant alteration of thymic glucocorticoid receptor density in males. Affinity of glucocorticoid and estrogen receptors did not differ from the controls significantly. The results demonstrate that the receptors of immature cells can be imprinted in adolescence similarly to those in the perinatal period and chemical substances capable of binding to the immature receptors can result in prolonged alteration of their binding character. This phenomenon should be taken into consideration especially in the case of nandrolone administration which can be used as a doping substance.

Animals↗

PubMed1993

Effect on inhibitors of glycoprotein synthesis (swainsonine, 1-deoxynojirimycin) on hormonal imprinting and lectin binding in Tetrahymena pyriformis.

Glycoprotein synthesis inhibitors (swainsonine = SW and 1-deoxynojirimycin = DNJ) influenced the insulin binding, insulin provoked hormonal imprinting and lectin binding of Tetrahymena. Insulin binding was increased and lectin binding decreased by both of them immediately after treatment, however, SW decreased insulin binding and both of them increased lectin binding after 24 h. SW inhibited, DNJ allowed the development of insulin imprinting. This means that the disturbance of glycosylation in general does not influence, but the blocking of mannosidase II disturbs the process of imprinting.

1-Deoxynojirimycin↗

PubMed1993

Uterus estrogen receptors' binding capacity is reduced in rat if exposed by benzpyrene neonatally.

During the critical period of receptor maturation within the first 5 days after birth female rats were treated with benzpyrene three times and their uterus estrogen receptor characteristic were examined in adulthood. Estrogen receptor density decreased significantly. There was no alteration in receptor affinity. Present experiment draws attention to the disadvantageous effect of aromatic hydrocarbons coming from the polluted air on steroid receptor development.

Animals↗

PubMed1993

The role of receptors of the plasma membrane and nuclear envelope in the failure of insulin imprinting in starving Tetrahymena.

Starvation for 2 h does not disturb the insulin binding of Tetrahymena. At the same time imprinting does not develop at the first encounter with insulin and a down regulation is observed after 168 h. Starvation for 2 h reduces the insulin binding of the nucleus to the half value after starvation for 24 h and this change in binding becomes settled by 48 h. Imprinting is not elicited either in the nuclear membrane. The down-regulation can be observed also after 48 h but it is not present in the 168-h measurements. The experiments emphasize the increased sensitivity of binding sites of the nuclear envelope and the role of it in the development of imprinting.

Animals↗

PubMed1993

Pheromone and insulin induced chemotaxis in Tetrahymena.

Cytodex spheres impregnated with insulin had a repellent effect at the first encounter and an attractive effect at the second encounter with Tetrahymena pyriformis. Tricosene, one of the two pheromones investigated had a positive chemotactic effect at the first encounter with the cells and this effect was increased following pretreatment (imprinting) with tricosene. Bornyl acetate expressed a negative effect on first use and was neutral on imprinted cells. The experiments demonstrate that not only hormones but also pheromones can serve as signal molecules for Tetrahymena. Moreover, the development of imprinting was observed. The effects and the imprintability were not a general characteristic of the pheromones which originate from the individual characters of the molecules. The development of imprinting can alter the direction of the effect of stimulus mediated by receptors.

Animals↗

PubMed1993

Nucleolar changes in the oocytes of newborn rats treated with follicle stimulating hormone (FSH).

In the ovaries of newborn rats the exogenous follicle stimulating hormone (FSH) given in a large dose leads to the appearance of uncommon structures in the nucleoli of the oocytes. Fuzzy filaments sometimes with chiasma-like connections appear and ring-like structures in connection with, or independent of, the nucleoli are seen. The results demonstrate the possible appearance of a morphological response of oocytes to FSH prior to any detectable biochemical or receptor binding evidence.

Animals↗

PubMed1993

The effect of an electric field on the release of hexosaminidase in Tetrahymena.

The activity of beta-D-hexosaminidase was detected by spectrofluorometry in the growth media of three species of Tetrahymena. The enzyme activity was about six times higher in T. pyriformis compared with the wild cells of T. thermophila, while the MS-1 mutant of T. thermophila manifested very low enzyme activity under the same experimental conditions. An electric field and electrical pulses produced significant though different increases in enzyme activity in media of wild and mutant T. thermophila. In contrast, T. pyriformis responded to the field pulses by decreasing the activity of the enzymes detected in the growth media.

Animals↗

PubMed1993

The effect of insulin on the liver cells of newborn rats. An electron microscopic study.

The liver of newborn rats contains neither glycogen nor lipid droplets. These latter, sometimes in fusion, still could be found in the cytoplasm and the nucleus as well, following a five-minute action of insulin at a dose of 0.2 IU/animal. The lipid droplets were in close relationship with the mitochondria. This time the glycogen, either in fields or rosettes, was missing. Thirty minutes after treatment the fields of glycogen could be well seen. The experiments demonstrated an exclusive sequence of events starting with the receptor and its signal insulin on neonatal liver cells and resulting in a morphological picture (involving first lipid droplets, then glycogen), similar to that of the adult liver cells.

Animals↗

PubMed1993

Response to thyroid stimulating hormone in 1-week-old rat thyroid gland after pretreatment with the same hormone in newborn conditions (hormonal imprinting).

Compared with control animals without hormone action, newborn rats treated with thyroid stimulating hormone (TSH) developed more exocytotic vesicles and enlarged endoplasmic reticulum filled with products in the thyroid gland up to the first postnatal week. A single administration of the hormone in newborn rats (imprinting) resulted in a long-lasting effect on the functioning of the cells of the thyroid gland. Single hormone action in postnatal 1-week-old animals provoked the discharge of products from the cells into the follicles of the thyroid gland with a concurrent endocytosis within 5 min after treatment. A similar but more vigorous effect was demonstrable in animals treated with TSH in newborn (hormonal imprinting) and postnatal 1-week-old conditions. Such events were accompanied by the death of certain cells while others developed myelin-like structures and showed signs of folliculogenesis in the cytoplasm.

Animals↗

PubMed1993

Fetal and neonatal action of a polycyclic hydrocarbon (benzpyrene) or a synthetic steroid hormone (allylestrenol) as reflected by the sexual behaviour of adult rats.

Allylestrenol or benzpyrene, given either between the 15th and 19th days of fetal life or from birth to the postnatal 7th day, caused dramatic decrease in the sexual activity of adult female rats. Allylestrenol, given in fetal life, resulted in a profound increase in the sexual activity of male rats. Given in newborn conditions, a decrease of sexual activity was caused by the same chemical. Considering, that one of the molecules has importance in medical practice and the other is an environmental pollutant, the experiments forecast the probability of modification in the sexual behaviour of human adults.

Allylestrenol↗

PubMed1992

Effect of vanadate and ouabain on insulin binding and insulin imprinting in Tetrahymena.

Na-metavanadate and ouabain that act on Na+K(+)-ATPase had no influence on insulin binding to Tetrahymena immediately after treatment, but after 24 h considerably enhanced the binding capacity of generations of progeny. The increase in binding was of a similar magnitude to that elicited by insulin imprinting. Vanadate failed to increase the imprinting potential of insulin while ouabain even prevented insulin imprinting when administered together with insulin, but, did not affect imprinting when administered after insulin. By analogy with higher organisms it appears that inhibition of Na+K(+)-ATPase plays no role in the insulin-like effect of vanadate on the unicellular Tetrahymena, as judged also from the capacity to bind insulin of the generations of offspring.

Animals↗

PubMed1992

Effect of inhibitors and activators of tyrosine kinase on insulin imprinting in Tetrahymena.

Primary exposure of Tetrahymena cells to insulin gave rise to hormonal (insulin) imprinting in the offspring generations, as judged from the increase in binding upon reexposure to insulin. Vanadate mimicked the action of insulin, inasmuch as it also induced imprinting for insulin, whereas the other tyrosine kinase activator tested, namely H2O2, had no such effect. However, combined treatment with vanadate+H2O2 + insulin induced a more pronounced imprinting for insulin than either insulin or vanadate on their own. The tyrosine kinase inhibitor genistein, a plant flavonoid, did not change the value for insulin binding significantly relative to the control immediately after exposure, but increased it slightly in the offspring generations after 24 h at high dilution. Upon combination with insulin, 10(-4)M genistein inhibited imprinting by insulin. These experimental observations suggest that there may be a key role for tyrosine kinase activity in the mechanism (development) of imprinting.

Animals↗

PubMed1992

Insulin antagonizes the phagocytosis stimulating action of histamine in Tetrahymena.

Histamine increased specifically the phagocytic activity of the unicellular Tetrahymena, whereas insulin had no influence on it. Insulin antagonized the phagocytosis stimulating action of histamine after simultaneous exposure and after preexposure two days earlier as well, although in the latter case to a lesser degree. Double exposure to a combination of histamine+insulin didn't influence the phagocytic activity at all, demonstrating the histamine antagonizing effect of insulin in this model.

Animals↗

PubMed1992

Effect of contraceptive treatment on thymic glucocorticoid receptors and hepatic microsomal enzyme system of adult rats.

Contraceptive steroid treatment accounted for about a 30 per cent decrease in the number of thymic glucocorticoid receptors of adult rats. Neonatal allylestrenol treatment had no influence on that treatment. The activity of the hepatic microsomal (PSMO) enzyme system was not changed by the contraceptive treatment. It appears that contraceptive treatment may account for overlaps on receptors in adulthood.

Aging↗

PubMed1992

Oxytocin and vasopressin change the activity of the contractile vacuole in Tetrahymena: newer contributions to the phylogeny of hormones and hormone receptors.

1. Primary interaction with oxytocin accounted for a significant prolongation of the time interval between two systolic contractions of the contractile vacuole in Tetrahymena, whereas primary interaction with vasopressin had no appreciable influence on that functional parameter. 2. Primary treatment (imprinting) with vasopressin increased sensitivity to vasopressin and reduced responsiveness to oxytocin. 3. Primary treatment (imprinting) with oxytocin did not increase cellular response either to oxytocin or to vasopressin on second exposure. 4. Oxytocin, which is chemically related to the antidiuretic hormone vasopressin, influences the water metabolism in protozoa; vasopressin develops a similar effect after imprinting. 5. The experimental observations allow conclusions on certain events involved in the phylogenesis of hormones and receptors.

Animals↗