Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 199 records · Page 11Linked to original sources

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↗

PubMed1992

The effect of thyrotropic hormone (TSH) on the thyroid gland of the newborn rat. An electron microscopic study.

The activity of the thyroid gland of the newborn rat is influenced by the treatment of TSH. Shortly after hormone injection, its effects can be detected in the synthesis and storage of the colloid. In a longer term (30 min and 60 min) the morphological signs of resorption and secretion are evident. At this early age the cellular compartments involved in the secretory pathway of the cells are still not complete in maturation (less developed Golgi complex, missing secretory vesicles and micropinocytotic vesicles). According to our results, even TSH administration cannot influence this picture in the short term. Our work supports the intracellular way of folliculogenesis, and the TSH action as a promoter in this way.

Animals↗

PubMed1992

Specificity of insulin binding by plasma and nuclear membrane receptors in Tetrahymena: similarities and dissimilarities at the two levels.

The plasma membrane and nuclear envelope of Tetrahymena are equally able to bind insulin both specifically and otherwise. Primary interaction with exogenous insulin (imprinting) accounted for an increase in the specificity of binding which became even more pronounced in the distant offspring generations of the imprinted cells. Virgin Tetrahymena cells not imprinted with insulin showed a greater specificity of insulin binding at the nuclear than at the plasma membrane level. This difference became equalized under the influence of imprinting with exogenous insulin which increased the specificity of binding at the plasma membrane level.

Animals↗

PubMed1992

Impact of starvation on hormone binding and hormonal imprinting in Tetrahymena.

Tetrahymena cells maintained (starved) in a physiological salt solution showed a considerable decrease in insulin binding capacity. The cells previously imprinted with insulin showed a comparable relative binding decrease after a similar exposure. This change was reversible by prolonged maintenance in plain nutrient medium after which the binding capacity of the imprinted cells increased appreciably over the control. The cells maintained (starved) in salt solution for 2 h were no longer imprintable with insulin; it follows that prolonged starvation not only reduced the recognition potential, but also extinguished the imprintability of Tetrahymena cells.

Animals↗

PubMed1991

EGF receptor induction and insulin-EGF overlap in Tetrahymena.

Offspring generations of Tetrahymena pretreated (imprinted) with insulin showed a greater binding capacity for the hormone than offspring of untreated ones. The epidermal growth factor (EGF) imprinted for insulin to a greater degree than insulin itself, and vice versa: insulin imprinted for EGF more efficiently than EGF itself. These phenomena can be explained by the overlap of insulin and EGF on one another's receptors in Tetrahymena.

Animals↗

PubMed1991

Impact of neonatal benzpyrene imprinting on thymocytic dexamethasone binding in ascitic tumor bearing rats.

1. Rats treated with a single dose of benzpyrene when newborn and inoculated with Walker's ascitic tumor cells when 6 weeks old showed 6 and 9 days later an unequivocal increase, whereas 15 and 20 days later an unequivocal decrease, in dexamethasone binding capacity (receptor number) relative to the control, i.e. a reversion of receptor activity in the course of tumor genesis. 2. The reversion of receptor activity showed a parallelism with the increase of tumor mortality over the control. 3. The experimental observations support the conclusion that neonatal exposure to benzpyrene has a depressive effect on general resistance that is reflected (or probably caused?) among others by a decrease in the binding capacity of glucocorticoid receptors.

Animals↗

PubMed1991

Lasting impact of a single benzpyrene treatment in pre-natal and growing age on the thymic glucocorticoid receptors of rats.

1. Rats exposed to benzpyrene in utero at 19 days of pre-natal life showed a relative decrease in the number of thymic glucocorticoid receptors at 6 weeks of age. 2. Primary exposure to benzpyrene at 6 weeks of age had a similar effect on females 4 weeks later, but did not change the glucocorticoid receptor number of males. 3. In utero exposure accounted for an increase in the fetal cytochrome P450 level within 1 day, whereas exposure at 6 weeks of age did not change it within 4 weeks. 4. It appears that exposure to benzpyrene gives rise to a faulty imprinting of the thymic glucocorticoid receptor in both fetal and growing age, to judge from a lasting change in the receptor number.

Aging↗

PubMed1991

Persistent influence of neonatal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treatment on glucocorticoid receptors and on the microsomal enzyme system.

Neonatal treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) accounted for a considerable decrease in the number of thymic glucocorticoid receptors in both male and female rats, as assessed at 6 weeks of age. TCDD also gave rise to a marked and prolonged increase in microsomal enzyme activity in the female rats but had practically no such effect on the males. These experimental observations attract attention on to the lasting microsomal inducer effect of the herbicide contaminant dioxin which damages foreign receptors and substantiate the chemical imprinting potential of aromatic hydrocarbons.

Animals↗

PubMed1991

Turnover and intranuclear localization of 125I-insulin in Tetrahymena. An autoradiographic study.

The unicellular Tetrahymena first internalized, then partly released the labelled insulin. Insulin-pretreated (imprinted) Tetrahymena cells behaved differently from non-pretreated cells, in that they retained a greater part of internalized insulin in the cytoplasm. Additional exposure to excessive non-labelled (cold) insulin caused a decrease in intracellular labelled insulin retention. Internalized insulin also entered the nucleus of Tetrahymena, where it was found in a heterochromatic localization.

Animals↗

PubMed1991

Impact of neonatal benzpyrene imprinting on liver microsomal enzyme induction by benzpyrene and phenobarbital in adulthood.

A single neonatal treatment of rats with benzpyrene accounted for a durable induction of the liver microsomal enzyme (PSMO) system. Neonatal treatment with benzpyrene enhanced the inducing action of phenobarbital administrated in adulthood, but did not change the effect of benzpyrene treatment in the adult age. It follows that the imprinting and inducing effects of the neonatal benzpyrene treatment took different trends.

Animals↗

PubMed1991

Binding of lectins (Con-A, lens, helix, PHA) to binding sites induced in Tetrahymena by insulin and lectins.

Concanavalin-A (Con-A) gave rise to a moderate aggregation in untreated (control) Tetrahymena pyriformis GL populations. The cells pretreated (imprinted) with insulin or lectins underwent aggregation earlier and to a greater degree than the untreated control cells. Lens lectin, although of the same sugar specificity as Con-A, was considerably less active than the latter. Helix lectin and phytohaemagglutinin (PHA), although of similar sugar specificity, accounted for a dissimilar extent of cell aggregation, in that Helix lectin was comparable in activity to Con-A. Pretreatment (imprinting) with insulin enhanced the aggregation inducing effect of those lectins which were capable of overlapping on the insulin receptor owing to similar specificity.

Animals↗

PubMed1991

Impact of neonatal benzpyrene pretreatment (imprinting) on the hepatic 3H-benzpyrene intake and output in adult rat liver. Investigation into the hepatic localization of benzpyrene in adult rats.

One hour after treatment with 3H-benzpyrene, grains appeared for the most part above the hepatocellular surface, heterochromatin and dense vacuoles, whereas 24 h later they were associated mainly with the dense vacuoles and smooth-surfaced endoplasmic reticulum and only, a few were still present above the heterochromatin. Neonatal pretreatment (imprinting) with benzpyrene accounted for an earlier appearance of benzpyrene in the hepatocytes relative to the non-pretreated control, but while labelled benzpyrene had practically disappeared from the liver of imprinted rats within 24 h, it still persisted in the liver of control rats at a level approximating the 4 h value.

Animals↗

PubMed1991

Impact of neonatal benzpyrene pretreatment (imprinting) on the hepatic 3H-benzpyrene intake and output in adult rat liver. Investigation into the hepatic localization of benzpyrene in adult rats.

Aging↗

PubMed1991

Influence of insulin and biogenic amines on the division of Chang liver cells after primary exposure (imprinting) and repeated treatments.

Cells of the Chang liver line responded differently to insulin and histamine exposure and re-exposure after five pretreatments. The mitotic index showed a considerable relative decrease 72 h after the last pretreatment. The response to serotonin did not differ between pretreatment and re-exposure. The effect of insulin and of biogenic amines was positive at the primary exposure and negative 72 h after repeated pretreatments.

Animals↗