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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 379 records · Page 21Linked to original sources
PubMed1983

A functional study of concanavalin A-histamine binding site overlap in Tetrahymena phagocytosis test.

Treatment with histamine stimulated the phagocytotic activity of the Tetrahymena to a measurable degree, which was still demonstrable after a week (about 40 generations). Concanavalin A, which binds to the same membrane binding site as histamine, inhibited the stimulatory action of subsequently added histamine, but did not in itself influence phagocytotic activity in any way. The inhibitory effect of Con A on the histamine binding site proved to be dose-dependent. These observations stress the importance of investigating the functional context--as sole realistic measure--of receptor--ligand bindings.

Animals↗
PubMed1983

Impact of neonatal treatment with cardioactive glycosides (digoxin, ouabain) on receptor binding capacity, blood level and cardiac function in the adult rat. Extension of the imprinting theory.

A single neonatal treatment with a cardioactive glycoside (ouabain, digoxin) altered the response of the adult rat to digitaloid treatment. As demonstrated by RIA, re-exposure to digoxin at 2 months of age was followed within 30 min by a more than twofold increase in serum digoxin over the not pretreated control and, although a steady concentration decrease followed, the experimental rats still had a higher serum digoxin level than the controls at 4 h. In the not presensitized control group the serum digoxin peak appeared at 60 min at a considerably lower level than the 30-min maximum of the experimental rats. Neonatal pretreatment with ouabain depressed myocardial ouabain binding, but enhanced the Na+ K+ -ATPase activity. The above differences were conspicuous in the functional response, yet a greater atrial response to the positive inotropic action of K-strophanthoside and a greater ventricular response to beta adrenergic excitation were readily seen in the experimental group. It follows that not only hormones, but also other ligands acting at receptor level can be regarded as potential inducers of imprinting.

Animals↗
PubMed1983

Lectins in the unicellular Tetrahymena. II. Impact of nutrition and sugar treatment on anti-lectin binding.

Tetrahymena pyriformis GL cells showed partly intracytoplasmic, partly intramembraneous accumulation of lectin-like proteins in conditions of starvation, as demonstrated cytochemically by reaction with antibodies to pea, lens, bean, Datura, and snail lectin. The lectins binding to simple sugars tended to accumulate in the membrane, whereas those capable of interacting with hexosamines in the cytoplasm. While the fluorescence pattern of lectin localization was generally homogeneous in normally nourished cells, it assumed a variegated appearance in starved cells, owing to patching of the membrane, and spot-like accumulation of lectins in the cytoplasm, presumably within membranes of endocytosed vesicles. Snail lectin was an exception, since its distribution remained homogeneous also in conditions of starvation.

Animals↗
PubMed1983

Lectins in the unicellular Tetrahymena. I. Lectin detection with FITC-labeled anti-lectins.

FITC-labeled antibodies prepared in rabbits to bean, pea, lens, datura, and snail lectin indicated by immunological reaction presence in the Tetrahymena of corresponding lectin-like components. The latter localized partly on the surface, partly inside the body of the unicellular. The specificity of the anti-lectins was ascertained by immunological and hemagglutination tests, and by examining antibody binding after pretreatment of the Tetrahymena with lectin or sugar.

Animals↗
PubMed1983

Comparative study of the internalization and nuclear localization of amino acid type hormones in Tetrahymena and rat lymphocytes.

Tetrahymena pyriformis GL cells and rat thymic lymphocytes equally showed intranuclear incorporation of triiodothyronine, diiodotyrosine, histamine, serotonin, epinephrine and corticosterone--used as control--on exposure to labelled hormones. All hormones appeared in the nucleus in a predominantly heterochromatic localization. Lymphocytes, although smaller in size, incorporated more hormone than Tetrahymena. The intranuclear accumulation of corticosterone did not differ between Tetrahymena and thymocytes, and was high in both relative to total incorporation by the cell. Autoradiographically detected localizations did not notably vary with the type of cell or hormone.

Amino Acids↗
PubMed1983

Incorporation of hormones and hormone-like materials by rat lymphocytes at different ontogenetic stages.

The quantities of hormones and hormone-like materials (histamine, dopamine, epinephrine, diiodotyrosine and corticosterone, in the following collectively: hormones) incorporated by the lymphocytes of neonatal rats were several orders greater than those taken up by the lymphocytes of adult rats. Uptake tended to decrease by one week of age, but it was still 2-3 times greater than in adulthood. It fell to a minimum at two weeks to one month of age, then it increased slightly by 2 or 6-8 months of age.

Amino Acids↗
PubMed1983

Influence of hormone concentration and time factor on TSH-FSH imprinting and overlap in CHO cells.

Exposure of Chinese hamster ovarian cell cultures (cell line CHO) to TSH of FSH gave rise to hormonal imprinting. In earlier studies re-exposure after 48 h displayed a considerable increase in hormone binding. In the present experiments similar increase was demonstrated with an interval of five days. After 14 days, the increment was of lesser degree or even a decrease was noted in hormone-binding capacity. Although the CHO line originates from the target cells of gonadotropin, long-term positive imprinting was greater for TSH than for FSH, imprinting for FSH being negative rather than positive. The experimental results suggest that even very low concentrations (10(-13) mol) of hormone induce imprinting after an exposure as short as 60 min.

Animals↗
PubMed1983

Attempt to disturb receptor memory in a unicellular (Tetrahymena) model system.

The effect of a hormone-like substance first reaching a receptor is of decisive importance in the unicellular (Tetrahymena) model system. The effect of the similar or dissimilar molecule after the first or second pretreatment depends to a great extent on pretreatment if it was carried out by a similar substance, but it does not depend on it if the agent used for pretreatment was different chemically. Receptor memory developing after hormonal imprinting can thus be disturbed by molecules of similar nature, but the effect of a different molecule--if it acts immediately after the imprinting--cannot be neglected, either.

Alkaloids↗
PubMed1983

Interaction of thyrotropin (TSH) and gonadotropins in the function of genital organs. Effect of TSH and gonadotropin pretreatment (hormonal imprinting) of newborn rats on hormonal overlap in adult animals.

At the age of 25 days the TSH-gonadotropin overlap is minimal in rats and extremely high doses of TSH are required to produce gonadotropin-like responses. Although the effect may be due also to some occasional contamination, nevertheless a single treatment of newborn animals (hormonal imprinting) with either hormone augmented the response to a second treatment with either hormone performed at 25 days of age. Newborn rats pretreated with either TSH or gonadotropin were exposed to a second TSH challenge at the age of 25 days exhibited responses which were not commeasurable to those observed after gonadotropin treatment alone. However, the amplifying action of TSH pretreatment with regard to the second response to gonadotropin was comparable or even more apparent than that of gonadotropin pretreatment.

Animals↗
PubMed1983

Influence of endocytosis-stimulating hormones on the protein binding capacity of the cell membrane.

Histamine and serotonin enhanced the adsorption of fluorescein isothiocyanate (FITC)-labelled bovine serum albumin (BSA) to the membrane of Tetrahymena in a statistically significant and biologically relevant degree, while the similar action of insulin and epinephrine was not significant in either respect. The degree of hormonal influence on BSA-binding was similar to that exerted by the same hormones on the phagocytosis of protozoa in earlier studies. This supports the hypothetical implication that enhancement of protein adsorption to the cell membrane is an important element in the endocytosis stimulating action of histamine and serotonin.

Animals↗
PubMed1983

Interaction of thyrotropin (TSH) and gonadotropins in the function of genital organs I. Investigations in the frog.

Earlier data indicate that TSH, which has a structure similar to that of gonadotropins, is able to evoke ejaculation in the frog (Galli-Mainini reaction). The present experiments provide evidence that TSH, in a dose that by itself is ineffective, is able to potentiate the effect of HCG. This action of TSH is more pronounced if the drug is administered prior to HCG; it is less evident upon simultaneous administration. Since FSH + LH has similar effects the experiments provide further evidence for the concept that TSH acts like gonadotropin in this system.

Animals↗
PubMed1983

Lectin (concanavalin A) binding to rat hepatocytes in different stages of cell differentiation.

A substantial part of hepatocytes originating from 19-day rat embryos are capable of binding concanavalin-A (Con-A) in the initial stage of culturing, and all embryonic hepatocytes acquire the binding property later on (until 24 days). Although the proportions of Con-A binding hepatocytes also are considerable in cultures derived from newborn and one-week old rats, they do not increase to 100% during culturing, and the cell of newborn rats show a marked decrease rather than increase in percentual Con-A binding capacity during the second part of the culturing period. The quantitative relations of Con-A binding sites were statistically identical in all age categories studied, and seem thus be independent of the age of the animal or culture.

Aging↗
PubMed1983

Effect of repeated treatments with sympathomimetic drugs on planarian glucose metabolism.

In response to sympathomimetic drugs (epinephrine, dopamine, isoproterenol, ephedrine), glucose utilization was enhanced in planarians. Upon repeated treatment with test substances one week after the first exposure the rate of glucose utilization differed from that observed at the first exposure. Under such conditions the responses appeared to vary depending on which of the drugs was used at the first exposure. After the elapse of two additional weeks the phenomenon (memory) was not further increased but the responses still differed from those recorded at the first exposure or two weeks after a single exposure.

Animals↗