Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 19 recordsLinked to original sources

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↗

PubMed1992

Benzpyrene exposure at 15 days of prenatal life reduces the binding capacity of thymic glucocorticoid receptors in adulthood.

1. The offspring of female rats treated with a single dose of benzpyrene on day 15 of gestation showed in adulthood a significant relative decrease in the number of thymic glucocorticoid receptors, without an appreciable decrease in binding affinity. 2. There is experimental evidence that exposure to a hormone analogue in the early stage of organogenesis effects receptor development and the maternal organism fails to confer protection against that untoward influence.

Animals↗

PubMed1992

Influence of gonadotropin (FSH + LH) and thyrotropin (TSH) on the multiplication of Chinese hamster ovary (CHO) cells. Impact of the age of the culture.

CHO cells repeatedly treated with gonadotropin showed peak division rates after their third exposure and a decrease in the mitotic rate after their fourth exposure. Thyrotropin induced a considerable decrease in the mitotic rate following the first exposure, a significant increase after the second and a further decrease following the third and fourth exposures. The pattern did not differ between the two hormones when the cells were exposed further. The age (density of the cell cultures) had an appreciable influence on hormone-provoked changes in the mitotic rate, this differing only in intensity and never in the response following the initial re-exposure.

Animals↗

PubMed1992

Life-long effect of a single neonatal treatment with estradiol or progesterone on rat uterine estrogen receptor binding capacity.

Rats treated with a single dose of 17 beta-estradiol or progesterone within 24 h of birth were subjected to ovariectomy at 8 weeks of age and were nine days later examined for the binding capacity of the uterine estradiol receptors by saturation and competition tests (with diethylstilbestrol used as competitor). The Bmax value of the neonatally estradiol-treated rats (6.78 x 10(-10) M) was significantly decreased relative to the control (1.99 x 10(-9) M). The competition analysis affirmed these results. Neonatal progesterone treatment also accounted for a significant decrease (1.25 x 10(-9) M) in receptor concentration relative to the control (1.66 x 10(-9) M). Considering the competition analysis the decrease was less than in the case of estradiol and not even significant by saturation analysis. The uterine mass did not differ between the experimental and control rats, but part of those treated with estradiol developed ovarian cysts. It follows that not only synthetic steroids (DES, allylestrenol), but also an excessive presence of the physiological steroid hormone during the critical period of receptor maturation can account for a decrease in uterine receptor concentration in adulthood.

Animals↗

PubMed1992

Impact of serum concentration of the medium and fasting on the imprintability of the insulin receptors of Chang liver cells.

When the cells of the Chang cell line came into interaction with a hormone (insulin) an imprinting-like phenomenon took place. The binding capacity of the receptors strengthened and this feature was transmitted to the descendant generations. The quality of the nutrient medium influenced the development of imprinting, when the cells were maintained in a medium containing 2% serum it was more difficult to evoke imprinting than in case the cells were kept in a medium containing 10% serum. If the cells were cultured kept in Tyrode (physiological) solution for 24 hours the possibility to evoke imprinting was lost. Difference could be observed between the behaviour of receptors in nuclear membrane and that of receptors in the plasma membrane; i.e. changes were more dynamic in the plasma membrane.

Cell Line↗

PubMed1992

Impact of single neonatal allylestrenol treatment on the estrus cycle of rats treated with FSH+LH or TSH.

Neonatal allylestrenol treatment administered to female rats significantly increases the duration of estrus phase in the sexual cycle. Treatment with follicle stimulating hormone (FSH) + luteinizing hormone (LH) in adulthood prolongs the duration of estrus even on its own; the effect, however, is more pronounced in those animals who were treated (imprinted) with allylestrenol neonatally. When administered to the control animals, the chemically related thyreotrop hormone (TSH) is either indifferent or it even decreases the estrus index. In animals having received neonatal allylestrenol treatment, however, TSH administration increases significantly the duration of the estrus phase. Either with or without FSH+LH treatment, the ratio of estrogenic to gestagenic phase increases following neonatal allylestrenol treatment. The experiments call attention to the potential functional risks inherent in neonatal allylestrenol treatment. The actual risks, however, seem to be smaller than the effects seen at the receptor level.

Allylestrenol↗

PubMed1992

Impact of combined hormonal pretreatment (insulin+TSH) on the imprinting of hormones administered in combination to Chinese hamster ovary cell culture.

Cultured Chinese hamster ovary (CHO) cells were treated (imprinted) with insulin and with thyrotropin (TSH) related to gonadotropins (FSH+LH). When one week later the treatment was repeated with one of the hormones, considerable differences could be observed in the binding capacity of the cells. In the hormone combination TSH was able to evoke persistent imprinting only to a markedly lesser degree than insulin, meanwhile the imprintatory effect of insulin was of greater extent even on the cell regarded to be unspecific for insulin. Hormone treatment of one hour duration--when investigated immediately after--did not extinct the binding capacity to TSH but enhanced that to insulin. With the deterioration of the conditions of culturing, the enhanced binding capacity disappeared.

Animals↗

PubMed1992

Specific insulin binding by, and imprintability of, the nuclear membrane of Tetrahymena.

Cellular nuclei isolated from Tetrahymena were able to bind FITC-labelled insulin, and pretreatment with different concentrations of unlabelled insulin accounted for a decrease in FITC-insulin binding of the nuclear membrane. This strongly suggests an association of specific insulin receptors with the nuclear envelope of Tetrahymena. Nuclei isolated 1 week after primary exposure of Tetrahymena cells to insulin showed a 50% binding increase over the controls. This supports the implication that hormonal (insulin) imprinting also involves the receptors of the nuclear membrane of the imprinted cells.

Animals↗

PubMed1992

Effect of pretreatments (imprinting) with different concentrations of insulin on insulin binding of nuclear envelope and plasma membrane in Tetrahymena.

About 4 h following treatment with 10(-6) - 10(-10) M insulin (imprinting) there was a down-regulation both in the plasma membrane and in the nuclear envelope of Tetrahymena, i.e. there was a decrease in the binding value related to the control. In each concentration tested the imprinting resulted in increased FITC-insulin binding after 24 and 48 h of treatment; the imprinting was independent of the concentrations. In the case of the plasma membrane the power of binding was directly proportional to the increase of the hormone concentration participating in the imprinting. For the nuclear envelope the optimal concentration was 10(-8) M. At very low concentrations (10(-10) M) the binding resulting in imprinting was insignificant in the plasma membrane but it was still present in the nucleus.

Animals↗

PubMed1992

Impact of weather changes on the growth of the unicellular Blepharisma undulans (Stein).

The growth of Blepharisma undulans (Stein) cells durably treated and not treated with insulin was followed up for three months with special regard a possible impact of meteorological factors on the growth rate. The growth rate of the protozoon was not appreciably altered by weather changes but the growth curves for cells treated and not treated with insulin indicated opposing trends of multiplication under the influence of approaching weather fronts. Warm fronts which have a parasympathic effect and cold fronts which have a sympathetic effect uniformly enhanced the growth rate of the untreated cells and retarded that of the insulin treated cells.

Animals↗

PubMed1992

Studies into secretions of Tetrahymena: enzymes secreted into inorganic medium.

The peptides secreted by Tetrahymena cells into inorganic medium were chromatographed. Six fractions showing a marked enzyme-like activity were examined for influence on certain physiological parameters of Tetrahymena. The enzymatically active fractions increased the phagocytic activity of Tetrahymena and decreased its binding capacity for lectins and hormone (insulin), but enhanced insulin imprinting at primary interaction. It remains to be clarified whether these effects were due to the enzymatic or other components of the fractions investigated, or to lack of the compensatory influence of the fractions not studied.

Animals↗

PubMed1992

Impact of a single insulin treatment (imprinting) applied during liver regeneration on hepatic insulin receptor development, blood glucose level and liver function parameters in adult rats.

Rats subjected to partial hepatectomy (surgical removal of two thirds of the liver) showed no appreciable change in serum cholesterol, bilirubin, albumin, total protein and A/G values at 2, 5, 12 and 21 days after the intervention. The enzyme activities characteristic of liver damage (GOT, GPT, LDH, AP) were high in the control group and low in the insulin-imprinted group at 2 days, tended to normalize in both groups at 5 days and changed slightly at 12 days. The blood glucose level was markedly decreased in the control group and to a lesser degree also in the experimental group at 2 and 5 days of sampling. Insulin treatment (loading) performed at 2 and 5 days accounted for a drop of blood glucose which was followed by normalization within 2 h. Starving value and response to insulin loading uniformly fell into the physiological range at 21 days, whereas at 12 days no normalization occurred in either group within 2 h of insulin loading, although the starving value was physiological. The binding capacity of the insulin receptor was markedly low in the control group as long as 12 days, and tended to normalize by 21 days. In the insulin-imprinted group the binding capacity increased over the control at 2 and 5 days and normalized by 12 days.

Animals↗

PubMed1992

Phospholipid content of untreated and insulin treated cells of Neurospora crassa (wall-less strain).

Phosphatidylcholine (51.2%) and phosphatidyl-ethanolamine (38.3%) are the most abundant phospholipids in the wall-less strain of Neurospora crassa. Insulin treatment exerted no change on the amount of phosphoinositides, although some previous results proved the existence of specific insulin receptors and specific effect of insulin on glucose metabolism in these cells. Long (20 h) treatment with insulin also failed to cause biologically significant changes.

Insulin↗

PubMed1992

Chloroquine inhibits the insulin binding and the imprinting of nuclear envelope in Tetrahymena.

Chloroquine possessing lysosomotrop effects inhibits the development of insulin imprinting both on the plasma membrane and the nuclear envelope. Simultaneously chloroquine can inhibit the insulin binding in the nucleus itself but not in the plasma membrane. There is a dose dependent increase of binding of labelled insulin to the nuclear envelope. The control related binding of nuclei pretreated with insulin or chloroquine is similar and have a direct ratio, independently of the applied concentrations.

Animals↗