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Biomedical subjects

J Kunert-Radek

Publications and source records attributed to J Kunert-Radek.

At least 73 records · Page 4Linked to original sources
PubMed1979

Biphasic inhibitory and stimulatory effects of thyrotropin on the mitotic activity of thyroid explants cultured in vitro.

An influence of thyrotropin (TSH), dibutyryl cyclic AMP (dbcAMP), triiodothyronine (T3) and thyroxine (T4) on the mitotic incidence in the organ-cultured rat thyroid was studied. The study has revealed biphasic inhibitory and stimulatory effects of TSH on the thyroid mitotic activity. The inhibitory effect occurred 14 h after an exposure of the thyroid explants to TSH and was enhanced by T3. A similar inhibitory effect was observed after an exposure of the explants to dbcAMP. 24 h after the exposure of the thyroid explants to TSH a stimulatory effect on the mitotic incidence was observed. The latter effect was not reproduced by dbcAMP.

Animals↗
PubMed1978

Ultrastructure of rat pinealocytes in vitro: influence of gonadotropic hormones and LH-RH.

The influence of gonadotropic hormones on the ultrastructure of rat pinealocytesin short-term organ culture was studied. Human chorionic gonadotropin (HCG), as well as pregnant mare serum gonadotropin (PMSG), caused a marked activation of pinealocytes. An hypothesis is discussed implying the presence of a feedback mechanism between the pineal organ and the hypothalamo-hypophysial system.

Animals↗
PubMed1978

Influence of cholinergic receptor blockade and stimulation on the anterior pituitary mitotic activity.

The effects of pilocarpine and atropine on the mitotic incidence in the anterior pituitary in male and ovariectomized estradiol-pretreated female rats was investigated. It was shown that pilocarpine stimulated, while atropine inhibited, the anterior pituitary mitotic activity. It was also shown that carbachol enhanced the mitotic incidence in the organ-cultured anterior pituitary and its effect was blocked by scopolamine. The existence of the muscarinic cholinergic receptor within the anterior pituitary, as well as its involvement in the control of the anterior pituitary mitotic activity, is suggested.

Animals↗
PubMed1977

Effect of thyroxine and of thyrotropin releasing hormone on cyclic AMP concentration in the anterior pituitary gland in vitro.

The effect TRH and thyroxine (T4) in vitro on the content of cAMP in the anterior pituitary gland in rat have been investigated. Thyroxine did not significantly affect this concentration, but TRH produced approximately a two-fold increase in the pituitary cAMP content. Preincubation of the anterior pituitary together with T4--under the conditions when the latter inhibited both proliferative and secretory response of the gland to TRH--did not prevent the elevation of cAMP due to TRH. It is assumed that T4 must have exerted its inhibitory effect outside of the cyclic AMP system.

Animals↗
PubMed1975

Investigations upon adenohypophysial cell proliferation in vitro: influence of oestradiol, thyrotropin releasing hormone, dibutyryl cyclic AMP and theophylline.

Mitotic indices were counted in adenohypophysial fragments cultured in vitromthe cultures exposed to 17-beta oestradiol, synthetic thyrotropin releasing hormone (TRH) and dibutyryl cyclic AMP showed a higher number of mitoses as compared with respective controls. However, theophylline decreased the mitotic index in cultured adenohypophysis.

Animals↗
PubMed1975

Influence of thyrotropin releasing hormone and dibutyryl cyclic adenosine 3',5'-monophosphate on ultrastructure of adenohypophysis in organ culture.

Ultrastructure of adenohypophysis in organ culture exposed to thyrotropin releasing hormone or dibutyryl cyclic adenosine 3',5'-monophosphate has been investigated. The features of increased secretory activity of glandular cells as well as the occurrence of a strongly osmiophilic substance in the intercellular spaces was observed in cultures exposed to both investigated factors.

Animals↗
PubMedDate not supplied

Effects of somatostatin and its analogues on tyrosine kinase activity in rodent tumors.

The effects of native somatostatin-14 (SS-14) and of its two analogues, octreotide and CH-275, on the activity of tyrosine kinases (TK) in two rodent tumors (rat pituitary tumor and murine colonic cancer) were studied in vitro. The activity of TK was measured in tissue homogenates using gamma[(32)P]ATP as the donor of the phosphoryl group and poly(Glu(80), Tyr(20)) as a substrate. It was found that native SS-14 inhibited TK activity in both investigated tumors. Octreotide, which acts preferentially via somatostatin receptor subtype 2 (SSTR2), was very effective in inhibiting TK activity in the rat pituitary tumor, but it is a rather weak inhibitor of TK activity in murine colonic cancer. CH-275, a selective ligand of the SSTR1 subtype of SS receptors, suppressed TK activity in the pituitary tumor but was ineffective in the colonic cancer. It is hypothesized that the effect of neuropeptide somatostatin (SS-14) on murine colonic cancer is exerted via the subtype of receptor which does not interact with CH-275 and has no or low affinity for octreotide (SSTR 4, 3 or 5?).

Animals↗
PubMedDate not supplied

Evaluation of interleukins, ACTH, cortisol and prolactin concentrations in the blood of patients with parkinson's disease.

Parkinson's disease (PD) is characterized by a markedly decreased number of nigrostriatal dopaminergic neurons. The pathogenesis of PD is still unknown; among other etiological factors, immunological abnormalities have been suggested. Recently, interleukin-2 (IL-2) has been hypothesized to be an endogenous cytokine that regulates striatal dopaminergic function. We examined the plasma concentrations of IL-1, IL-2, IL-6 and blood levels of ACTH, cortisol and prolactin of 21 patients with PD without any previous treatment. Age- and sex-matched subjects without any neurological or immune disorders were used as controls. Significantly higher serum concentrations of IL-2 in patients with PD were found. Treatment with antiparkinsonian drugs reduced IL-2 levels in these patients. Our results suggested a functional relationship between central dopaminergic and immune systems and a possible involvement of the latter in the pathogenesis of PD.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

[Pituitary resistance to thyroid hormone--a case report].

Pituitary resistance to thyroid hormone is a very rare cause of hyperthyroidism. It is characterized by normal, or elevated TSH concentration with high concentration of T3 and T4. Here, we present a case of a 24-year-old woman who suffered from mild thyrotoxicosis and diffuse goiter for several years. She had elevated fT3 and fT4 with slightly elevated TSH concentration. Pituitary adenoma was excluded as magnetic resonance imaging showed normal pituitary gland, alpha subunit was within normal range and TSH concentration increased after TRH administration. Sonography revealed normoechogenic, slightly enlarged thyroid gland. Previously, she was given thiamazole, but without any significant amelioration. Thus, the diagnosis of the syndrome of pituitary resistance to thyroid hormone was established. The patient was given bromocriptine at a dose of 10 mg per day. After 2 months of treatment she achieved a state of constant euthyrosis and following next few months thyroid volume diminished.

Adult↗
PubMedDate not supplied

Diazepam inhibits proliferation of the mouse spleen lymphocytes in vitro.

The effects of diazepam (1-100 microM) on the incorporation of 3H-thymidine into DNA of the mouse spleen lymphocytes in vitro have been investigated. A dose-dependent inhibition of lymphocyte DNA synthesis has been found. A 70% inhibition occurred with 100 microM diazepam concentration.

Animals↗