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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 217 records · Page 12Linked to original sources
PubMed1991

An attempt at transmission of hormonal imprinting between foreign cell lines.

Hormonal imprinting is transmitted from imprinted to virgin cells of the same cell line. No transmission of imprinting occurred between Chinese hamster ovary (CHO) and human Chang liver cells, and the presence of the latter reduced rather than enhanced the thyrotropic hormone (TSH) binding capacity of the CHO cells. While hormone binding capacity was relatively homogeneous in the control and the mixed cell cultures, it was not homogeneous in the homologous imprinted plus virgin cell population, indicating a continuous transmission of imprinting from the former to the latter.

Animals↗
PubMed1990

Involvement of the phosphoinositol (PI) system in the mechanism of hormonal imprinting.

Certain components of the phosphoinositol (PI) system are present in the unicellular Tetrahymena. Treatment of Tetrahymena with insulin did not alter the relative proportions of the examined six phospholipid components (PIP2, PIP, phosphatidylcholine, phosphatidylethanolamine, PI, PA), but the primary interaction (imprinting) with insulin accounted for an about 75% decrease in the PIP2-level and an about 20% increase in the phosphatidylethanolamine level. The experimental results strongly suggest that hormonal imprinting accounted for adjustment of the second messenger systems of Tetrahymena to an energy saving level.

Animals↗
PubMed1990

Impact of 5-azacytidine on insulin binding and insulin-induced receptor formation in tetrahymena.

The unicellular Tetrahymena is able to bind the vertebrate hormone insulin, and the binding sites presented by it become amplified under hormonal influence. The increased binding capacity for insulin reappears in many offspring generations. 5-azacytidine inhibits insulin binding and the insulin-induced formation of binding sites as well in the cell generation directly involved in interaction, but enhances insulin binding in the daughter cell generations. The nutrient medium of the cells whose binding capacity was enhanced by azacytidine treatment transmitted the information accounting for increased binding to "virgin" cells not previously treated with azacytidine.

Animals↗
PubMed1990

Evidence of the receptor nature of the binding sites induced in Tetrahymena by insulin treatment. A quantitative cytofluorimetric technique for the study of binding kinetics.

Tetrahymena pyriformis GL cells pretreated (imprinted) and not pretreated with insulin showed dissimilar quantitative relations of FITC-insulin binding. Displacement of FITC-insulin by unlabelled insulin was considerably less in the control than in the imprinted series. The curve for saturation of the binding sites with FITC-insulin resembled a true saturation curve. The imprinted cells bound considerably more hormone in a shorter time than the control cells at identical levels of exposure. The dissociation of bound hormone from the imprinted cells increased over the control at 23 degrees C, and to a still greater degree at 4 degrees C. The effect of the pH of the medium on the dissociation of bound FITC-insulin also differed between the imprinted and not imprinted cells. Thus the proposed cytofluorimetric assay of binding kinetics demonstrated the actual conditions of receptor activity, and indicated that the induced insulin binding sites of Tetrahymena behaved similarly to 'classical' receptors.

Animals↗
PubMed1990

Cytoplasmic manifestation of the nuclear membrane's hormone binding capacity during cell division.

Binding of insulin and thyrotropic hormone (TSH) to the nuclear membrane of Chang liver cells was demonstrated by qualitative and quantitative cytofluorimetry, which failed to substantiate a similar binding affinity for BSA. It appears that in the dividing cell the binding structures (receptors) of the nuclear membrane migrate in the cytoplasm together with the chromosomes by the end of the prophase and become reorganized in the nucleus around the telophase. The fluorescence which indicated binding also appeared in the midbody region during division of the two daughter cells. These experimental observations strongly suggest that, after cell division, only part of the nuclear membrane's receptor complement has to be resynthesized in the daughter cells, because the receptor number required by a single cell is conserved in cytoplasmic membrane details of nuclear membrane origin.

Animals↗
PubMed1990

Influence of imprinting with A and B chains of insulin on binding and functional changes in tetrahymena.

Insulin and its A and B chain increased the quantity of intracellular PAS-positive material (glycogen) in tetrahymena, whereas the combined A + B chains decreased it. Imprinting--previous interaction--with insulin, its A and B chains in themselves and with the A + B chain increased the hormone binding capacity of tetrahymena, but the functional effect of imprinting (storage or breakdown of glycogen) showed a different tendency with insulin and A + B chain on the one hand, and A chain and B chain on the other. Since the imprinting potential of a molecule promotes the induction of receptor formation, the fact remains that both component chains of insulin were able to act as potential imprinters, although the A chain was superior to the B chain in this respect throughout, and combined treatment with the A + B chain ultimately induced the formation of a similar binding site as insulin itself.

Animals↗
PubMed1990

Effect of insulin imprinting on the 3H-amino acid uptake of the Tetrahymena.

Insulin imprinting given to the unicellular Tetrahymena considerably increases the uptake and intracellular storage of amino acids even many generations after the actual contact with the hormone. On the other hand, both the first and the second contacts with insulin increase the rate of the excretion of the stored amino acids. On the basis of the results obtained it seems to be possible that both protein synthesis and exocytosis of the Tetrahymena change as an effect of imprinting, either in general or specifically due to the formation of new hormone receptors.

Amino Acids↗
PubMed1990

Influence of enkephalins on the ACTH-induced hormonal imprinting in tetrahymena.

Both adrenocorticotrop hormone (ACTH) and the synthetic enkephalins investigated evoked imprinting in Tetrahymena and led to increased hormone binding at further contact with ACTH. Neither molecule evoked, however, imprinting for the enkephalins. The pentapeptide enkephalin containing also proline had the most pronounced imprinting effect and, when given together with ACTH, it increased the imprintatory effect of ACTH considerably. In all the situations investigated the enkephalin tetrapeptide inhibited the positive effect of the enkephalin pentapeptide, whereas it did not influence the imprintatory effect of ACTH. Similarities can be found between the pharmacological and imprinting effects of enkephalin in mammals, and the effects seen in the present investigations.

Adrenocorticotropic Hormone↗
PubMed1990

Effect of insulin, prednisolone and diiodothyronine on 3H-uridine intake and localization in Tetrahymena.

Quantitative light and electron microscopic autoradiography demonstrated a dissimilar effect of insulin, prednisolone and diiodothyronine on the incorporation and localization of 3H-uridine in Tetrahymena. After treatment with insulin for 1 h, uridine was rapidly incorporated, and after initial accumulation in the cytoplasm its intracellular level tended to drop below the control. Total uridine incorporation was lower than in the control cells. In Tetrahymena treated with prednisolone or diiodothyronine, uridine incorporation was relatively slow, but the intracellular uridine level increased significantly over the control. Re-exposure to the hormone had no significant influence in the case of insulin, but altered the quantitative relations of uridine incorporation significantly in the case of the morphogenetic hormones prednisolone and T2.

Animals↗
PubMed1990

Effect of gonadotropin (FSH-LH) and thyrotropin (TSH) treatment in adolescence on TSH-sensitivity in adult rats.

Hormonal imprinting is characteristic of the neonatal age, in which the receptor of the target cell matures, i.e. acquires its adult binding capacity, and cellular response becomes established in presence of the adequate hormone. The normal course of imprinting may be altered by certain molecules (related hormones, hormone analogons) which are able to bind to the receptor of the adequate hormone. The chemically related gonadotropic and thyrotropic hormones may overlap on each other's receptors not only in the perinatal age, but also in the early adulthood, and this overlap of the binding may give rise to an imprinting-like effect. An example of this phenomenon was observed in the present study, in which rats of seven weeks of age treated with gonadotropin showed a significant decrease in thyroidic response to TSH, and exposure to TSH failed to increase their basic thyroxine concentration to the normal (control) level. This depressive effect of gonadotropin was slightly reduced in the presence of LPS (endotoxin), causing membrane perturbation, while pretreatment with LPS and TSH accounted for an increased sensitivity to TSH in later phases of the rat's life. These experimental observations support the possibility of a special form of imprinting in adolescence.

Aging↗
PubMed1990

Persistence of receptor "memory" induced in Tetrahymena by insulin imprinting.

Tetrahymena cells treated (imprinted) with insulin on a single occasion bound significantly more insulin than the control cells for as many as 70 days, i.e. over 664 generation changes. Although late reexposure to insulin reduced the binding of labeled hormone for 24 h, the binding value of the imprinted cells still increased significantly over the control. Maintenance under anaerobic conditions for 80 days accounted for a temporary suspension of the effect of imprinting which was, however, recovered within a week of return to aerobic conditions, in an even stronger form than observed in cultures maintained without an anaerobic episode. The experiments demonstrated that the imprinting-induced receptor "memory" lasted long, but was vulnerable to treatment with another polypeptide hormone.

Animals↗
PubMed1990

Cell-to-cell transmission of hormonal imprinting persists long in Tetrahymena.

Replicating and replication-inhibited (maintained under anaerobic conditions) Tetrahymena cells were still able to transmit to "virgin" cells insulin-induced hormonal imprinting after four weeks, i.e. after about 220 to 280 generation changes. The effect of imprinting was not uniformly demonstrable during that period, and the cells maintained under anaerobic conditions even showed a decrease in insulin binding capacity after two weeks. It appears that in the majority of the cases, the intensity of transmitted imprinting greatly depends on that of the genuine imprinting.

Animals↗
PubMed1990

Duration of the microsomal enzyme (cytochrome b560ms) inducer action and imprinting potential of a steroid in Tetrahymena.

Tetrahymena subjected to a three-day exposure to the steroid triamcinolone exhibited a decreased microsomal enzyme activity, three days after treatment, followed by a slight and a considerable activity increase over the control at one and two weeks after treatment, respectively. Reexposure to triamicinolone after return to plain medium for three days accounted for a marked increase in the inducer action which, however, failed to persist for an appreciable time.

Animals↗
PubMed1990

Overlap of concanavalin-A and insulin imprinting in rat thymocytes.

The thymocytic insulin binding in rats treated with the hormone neonatally on a single occasion increased considerably compared to the untreated control by 3 months of age. Treatment with Concanavalin-A also accounted for an increase in adult insulin binding, whereas neonatal treatment with insulin did not alter the binding relations of Concanavalin-A in adulthood.

Aging↗
PubMed1990

Permanence of the cell-to-cell transmission of insulin induced hormonal imprinting.

When insulin-treated (imprinted) Chang liver cell cultures were mixed with cultures which did not receive insulin treatment the information of imprinting was transmitted to the cultures which were not in direct contact with insulin. The ability of the cells to transmit imprinting was long lasting and could be detected even after four weeks, when it was nearly of the same degree as at the first measurement. Difference was found between the binding capacity of the receptors of the plasma membrane and those of the nuclear membrane.

Animals↗
PubMed1990

Impact of pretreatment (imprinting) with insulin on insulin-induced mitotic activity in Chang and CHO cell lines.

Primary interaction with insulin increased the mitotic activity of Chang liver and Chinese hamster ovary (CHO) cells. Re-exposure to insulin accounted for a significant increase of mitoses over the control, but for a considerable decrease thereof relative to the effect of primary exposure. The hormone had a more pronounced effect on its direct target cells (Chang liver cells) than on the CHO cells.

Animals↗