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Biomedical subjects

G Csaba

Publications and source records attributed to G Csaba.

At least 433 records · Page 24Linked to original sources
PubMed1981

Investigation of histamine-antihistamine differentiation ability of Tetrahymena receptors, by means of lectins and antihistamine antibodies.

Histamine antagonists bind to the histamine receptors of Tetrahymena, and their presence can be shown by immunocytofluorimetry. The binding of histamine is inhibited by antagonists structurally similar to histamine, regardless whether they bind to H1 or H2 receptors, but it is not inhibited by phenindamine, a compound structurally highly different from histamine. That part of H1 receptor which binds to both concanavalin A (con-A) and histamine probably contains primarily simple sugars, and secondly, glycosamine oligomers. At the H2 binding sites, on the other hand, acetylgalactosamine and its derivatives dominate. The present findings in the light of earlier functional experiments, suggest that in Tetrahymena, binding and effect are separated from each other to a certain degree.

Animals↗
PubMed1981

Effect of cortisol, deoxycorticosterone and 19-nortestosterone on the gametogenesis of the snail Helix pomatia.

Gametogenesis of the snail was shown to be affected by cortisol, deoxycorticosterone and 19-nortestosterone. An activation of the ovogenetic apparatus while uncertain responses of spermiogenesis were observed. On the basis of effects of non-gonadospecific steroids it is concluded that the receptors of the snail's spermiocytes are not selective. The spermatogenesis was influenced more significantly by 19-nortestosterone as compared to testosterone, having been examined earlier.

Animals↗
PubMed1981

Effect of high-dose thyrotropic hormone treatment on the cells of the newborn rat thyroid.

Newborn rats were given 5 I.U. thyrotropic hormone (TSH) either in a single dose or in daily 1 I.U. doses for 5 days. The treatment resulted in the activation of only certain cells of the follicular epithelium. This suggests that the thyroid is responsive in newborn age but not all its cells react. The differences in the response to TSH may be due to different timing of receptor maturation, to the phasic nature of response and to the uneven presence of receptors. It is assumed that cells possessing receptors multiply to form the mature tissue.

Animals↗
PubMed1980

An immunocytochemical method for histamine detection.

An anti-histaminic immune serum, prepared in New Zealand male rabbits by immunization with a chemospecific antigen (diazotized para-amino-benzoyl-azohistamine) was labeled with fluorescein isothiocyanate for the purpose of histamine detection or was employed for demonstration of histamine using fluorescein-labeled protein A. The IgG fraction of the hyperimmune serum was isolated, purified, and tested for specificity by binding to 3H-histamine or to histamine-containing or histamine-treated cells. Histological preparations used for detection of histamine should be fixed preferably in Carnoy solution. The procedure can also be employed for ultra-histochemical detection of histamine, using ferritin-conjugated antibody or the peroxidase technique.

Animals↗
PubMed1980

Amplification of hormone receptors by neonatal oxytocin and vasopressin treatment.

Newborn rats were treated once with 2 Units of vasopressin (VP) or oxytocin, respectively. At the age of 2 months and 1 year, respectively, the reactivity of isolated aortic strips to vasopressin and noradrenaline was tested. In young adults animals vasopressin pretreatment enhanced whilst oxytocin pretreatment decreased the responsiveness of aortic strips to VP. In elder specimens both types of pretreatment resulted in an increased late sensitivity to VP. The norepinephrine-sensitivity was higher in the young adults pretreated with oxytocin, whilst in the elder ones vasopressin-retreatment gave the same late effect. It could be established that the hormone excess produced in the neonatal age led to the "amplification" of hormone receptors and this alteration provided to be permanent. A compound which is similar to but not identical with the hormone--in our case, oxytocin--would elicit an alteration of a less unindirectional and permanent type; late sensitivity changes in both directions may occur.

Age Factors↗
PubMed1980

Durable sensitization of hormone receptors during differentiation in regenerating planarians by treatment with homologous or analogous hormone molecules.

Hormonal (dopamine, epinephrine) treatment of planarians during total regeneration (sensitizing treatment) resulted in amplification of the receptors, which accounted for an increased response to later hormone exposure (provocative treatment). While not presensitized specimens showed an identical increase of glucose uptake upon provocative treatment with either hormone, dopamine proved to be more active than epinephrine regardless of homologous or analogous presensitization. The glucose-uptake-enhancing effect of dopamine was independent of the presensitizing dose level, whereas that of epinephrine was not, having increased as the presensitizer concentration was elevated. The experimental observations indicate that the hormone receptors may become modified, i.e. durably amplified, during the differentiation stage and that exposure of the differentiating receptor to a structurally dissimilar, analogous molecule may result not only in deformation, but also in amplification of the receptor.

Animals↗
PubMed1980

Changes of receptor cooperation in Tetrahymena by re-exposure to hormones.

The hormone combination epinephrine + diiodotyrosine inhibited the growth of Tetrahymena cells on first exposure, but stimulated it markedly on re-exposure. It appears that amplification of the receptor by the hormone does take place at the first encounter, regardless of whether the response of the cells was positive or negative. The amplifying effect persists over several generations. The intensity of stimulation by the second exposure was directly related with the duration of the first one. Prolongation of the first exposure accounted for a switch-over from negative to positive influence.

Animals↗
PubMed1980

Long lasting amplification and deformation of thyroid receptors after thyrotropin (TSH) and gonadotropin (GTH) treatment of chickens in the foetal period.

Gonadotropin or TSH treatment of the chick embryo influences the T4 production of the one-month-old animal if TSH is given on a second occasion. Hormone treatment on the 8th day of life was ineffective, while previous treatment of the 12-day-old embryo resulted in a significantly more pronounced elevation of serum T4 level compared to the control when provoked by TSH in the one-month-old animal and a significant reduction in the animals subjected to gonadotropin pretreatment.

Animals↗
PubMed1980

Receptor amplifying effect of serotonin and serotonin analogues in a protozoan (Tetrahymena) model system.

A 72-hour treatment of Tetrahymena with serotonin analogues at a concentration of 10(-9) mmole/l resulted in a decrease of the reproduction rate, whereas serotonin itself was ineffective. On the second exposure to antagonists, cellular division was enhanced but its rate remained around or below the control value, while the second exposure to serotonin produced a more marked effect than the first one did, which finding implies a receptor amplification. The most pronounced receptor amplification was caused by the first exposure to serotonin. This observation indicates that the receptor is rather selective as regards the amplification effect.

Animals↗
PubMed1980

Dose dependence of the thyrotropin (TSH) receptor damaging effect of gonadotropin in the newborn rats.

A single gonadotropin treatment of newborn rats influenced the thyrotropin (TSH) provoked thyroxine (T4) production of 2 months old animals. On pretreatment with 10, 20, 50, 100 and 200 I.U. of gonadotropin, the T4 blood level of animals given 10 and 200 I.U. differed scarcely from the controls treated only by TSH, while intermediary doses had a damaging effect as the T4 values were well below the control values measured in animals treated by TSH in adulthood.

Animals↗
PubMed1980

Detection of histamine binding sites (receptors) in Tetrahymena by fluorescence technique.

Examinations with fluorescein isothiocyanate (FITC)-bovine serum albumin histamine conjugate and with FITC-labeled antibodies to histamine have shown that the unicellular Tetrahymena possess histamine binding sites (receptors) which are localized on the cilia of the cell body. No histamine is bound by the interciliar membrane regions and by the cilia of the oral fields.

Animals↗
PubMed1980

Histological analysis of the overlapping effect of hypophyseal hormones on the cockerel's testes.

Histological examination of cockerel testes revealed the overlapping effects of FSH and TSH. Within the dose-range studied (20-160 microgram FSH and 27.5-220 microgram TSH), both hormones increased the cell number in the seminiferous cords including the number of spermatogonia, primary spermatocytes and pre-Sertoli cells. They also enhanced the mitotic activity of spermatogonia and accelerated spermatogenesis. Peak effects were observed after treatment with 160 microgram FSH and 55 microgram TSH dose. Liquefaction of cords due to hormone treatment was indicative of an acceleration of testicular ontogeny. Cross-effects of the two hormones were explained by receptor immaturity i.e. in the early stage of ontogenesis the receptors can bind both hormones due to the similarities in their structure. The maximum effects of the hormones were different, that of FSH being more marked.

Animals↗
PubMed1980

Effect of combined gonadotropin-thyrotropin treatment on development of testis and ovarium in the chickling.

Both TSH and gonadotropins stimulate the gonads in the perinatal period. Gonadotropins influence primarily the parenchyma and they induce an increase in the diameter of seminiferous tubules, and of the thickness of the ovarian cortex. TSH acts primarily on the interstice, but it acts also on the parenchyma and this action is more pronounced in the testis than in the ovary. The hormones can replace each other, and gonadotropins enhance the effect of TSH on the interstice.

Animals↗