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V Schreiber

Publications and source records attributed to V Schreiber.

At least 19 recordsLinked to original sources
PubMed1992

[Correlation between urinary excretion of neopterin and levels of thyroid gland hormones in patients with goiter].

The authors assessed in 18 patients with goitre the urinary excretion of neopterin and the blood level of thyroid hormones. They revealed a significant correlation between urinary neopterin excretion and the thyroxine (T4) and triiodothyronine (T3) blood level. This correlation did not apply in female patients treated with large doses of Carbimazol: these patients had a high neopterin excretion, while the thyroid hormone levels were only slightly elevated. This suggests again that Carbimazol has in addition to an antithyroid effect also an immunomodulating action.

Biopterins↗
PubMed1992

[EDRF-NO. The endothelium-derived relaxing factor is nitric oxide].

The author reviews findings assembled during the last 20 years on the endothelium-derived relaxing factor (EDRF), and in particular findings assembled the last five years which revealed that EDRF is identical with nitric oxide, NO. The enzyme NO synthetase produces NO from l-arginine with the concurrent formation of citrulline and is present not only in the endothelium of the vascular wall but also in cerebral neurons and other tissues. NO is probably also the effective factor of the vasodilatating action of organic nitrates (nitroglycerol, amyl nitrite, sodium nitroprusside). In recent years these findings are applied also in clinical work. In atherosclerosis of the coronary vessels NO formation is obviously reduced and l-arginine infusion may improve the coronary blood supply in patients with hypercholesterolaemia. Inhalation of NO has been tried in pulmonary hypertension. Antidotes of NO (methylene blue) conversely may prevent hypotension in hepatic failure. Infusion of an antidote of l arginine prevents hypotension in septic shock. This is due to the fact that an excess of NO is formed from macrophages during infections. NO is, however, also mutagenic and there are reports on its participation in the genesis of genetic and neoplastic diseases.

Animals↗
PubMed1992

The human poly(ADP-ribose) polymerase nuclear localization signal is a bipartite element functionally separate from DNA binding and catalytic activity.

Poly(ADP-ribose) polymerase (PARP, EC 2.4.2.30) is a zinc finger DNA-binding protein involved in DNA repair processes in eukaryotes. By deletion and extensive site-directed mutagenesis, its DNA-binding domain fused to the N-terminus of beta-galactosidase was shown to contain a nuclear localization signal (NLS) of the form KRK-X(11)-KKKSKK (residues 207-226). In vitro, both the DNA-binding capacity and the polymerizing activity of PARP are independent of the nuclear location function. Each basic cluster is essential but not sufficient on its own for this function, while both motifs together are. Crucial basic amino acids (K207, R208 and K222) in each of these two motifs are required for nuclear homing. The results presented here support the concept that the human PARP NLS is an autonomous functional element and belongs to the class of bipartite NLSs. We show that the linear distance between the two basic clusters is not crucial. Insertional mutation analysis leading to a partial reversion of the cytoplasmic phenotype displayed by the mutant K222I highlights the crucial positioning of this lysine. The structure-function relationship of the second cluster of basic residues is discussed.

Amino Acid Sequence↗
PubMed1992

Different effects of oestradiol benzoate and norethisterone on the blood flow and mineral content in rat bones.

In three experiments (2 on females, 1 on males), we determined the blood flow in the tibia and the distal part of the femur, together with cardiac output (by means of 85Sr-microspheres), tibial bone density and tibial ash weight related to bone volume. We found that 1) the bone blood flow always fell significantly after oestradiol benzoate, 2) no change occurred after norethisterone in doses corresponding to those of oestradiol benzoate, but the blood flow showed a tendency to fall after doses one order higher (it decreased significantly in one case only), 3) the density of the tibia and tibial ash weight related to bone volume rose nonsignificantly after oestradiol benzoate, but fell (mostly statistically significantly) after norethisterone. The lowering of the bone mineral indexes in rat bones after norethisterone is a surprising and potentially significant finding requiring further verification.

Animals↗
PubMed1992

The increase in cAMP and cGMP levels in the oestrogenized rat hypophysis.

Male and female rats were given oestradiol benzoate (1 mg s.c. twice a week for 3 weeks) and/or sodium nitroprusside (SN), a donor of nitric oxide (NO), which was administered in their food in amounts of 0.2 or 0.6 mg/rat/day. Neither oestradiol-induced hypertrophy of the hypophysis, nor the serum prolactin (PRL) level, was affected by the simultaneous administration of SN. The PRL content of the hypophysis rose after oestradiol in the males, but the increase was again uninfluenced by the simultaneous administration of SN and the cAMP content of the hypophysis--raised after oestradiol--was likewise unaffected. The amount of cGMP in the hypophysis after oestradiol rose only in males. Both the serum and the hypophyseal prolactin level were found to be correlated to the cAMP and the cGMP content of the hypophysis. It was found that the simultaneous administration of SN together with oestradiol slightly reduced the increase in the cGMP content of the hypophysis elicited with oestradiol treatment only.

Animals↗
PubMed1992

[A new agent--nitric oxide].

A review of findings pertaining to EDRF (endothelium derived relaxation factor) which proved to be nitric oxide, NO. After an account of the vasodilatating action of NO in the cardiovascular system the main attention is devoted to macrophages, the source of NO and to the formation of NO during activation of infections and during septic shock. NO participates also in the cytotoxicity of macrophages. NO may be the cause of hypotension in hepatic failure. Cumulation of endogenous inhibitors of NO formation in renal failure may be the cause of hypertension. The author analyzes other clinical effects of NO with regard to impotence and diabetes: NO stimulates insulin secretion from the B-cells of the islets of Langerhans. Attention is also drawn to the possible function of NO in the pituitary, in particular with regard to the arginine test which stimulates STH secretion.

Animals↗
PubMed1991

[Endocrinology 1990-1991].

The author presents an account of selected important findings in endocrinology during the last year. The mediator of action of STH, IGF-I, was tested as a protein anabolic in a child with Laron's nanism. STH is about to be tested as a geriatric drug. A non-peptide vasopressin antagonist was described. Melatonin is being tested in sleep disorders. A combination of methimazol and thyroxine is more suitable for treatment of Graves-Basedow's disease than the goitrogen alone. Dermal vasoconstriction can be an indicator of the effectiveness of glucocorticoids in asthma. Significant advances were made in the sphere of the new hormone, NO: it is not only an effective vasorelaxing agent but also a neuromodulator and participates in the natural lymphocytic cytotoxicity. Marked advances were made as regards knowledge of the endogenous ligand for benzodiazepine receptors.

Endocrine System Diseases↗
PubMed1991

[Endocrinology 1989-1990].

In a brief review the author presents selected results of endocrinological research, published in 1989 to 1990. In the sphere of peptide hormones he mentions findings on the reduced level of the endothelial relaxation factor in the blood stream in atherosclerosis, the classification of endothelin with neuropeptides and the existence of a vasopressin antagonist which causes polyuria after operations of the hypothalamus. Hybrid hormones (biotechnologically prepared combined molecules), mammastatins (inhibitors of proliferation of mammary cell cultures lacking in transformed cultures) and adipsin (a peptide factor lacking in some types of experimental obesity) are other recent advances. Findings on endogenous benzodiazepine substances (occupying receptors for diazepines) and of an endogeneous factor for receptors for tetrahydrocanabinols supplement the contemporary picture. Adrenocortex stimulating immunoglobulins may be the cause of hyperplasia of the adrenal cortex, similarly as TSI is the cause of Graves-Basedow's disease. In the latter evidence of a retroviral aetiology was provided.

Cushing Syndrome↗
PubMed1991

Poly(ADP-ribose) polymerase: molecular biological aspects.

A number of roles have been ascribed to poly(ADP-ribose) polymerase* including involvement in DNA repair, cell proliferation, differentiation and transformation. Cloning of the gene has allowed the development of molecular biological approaches to elucidate the structure and the function(s) of this highly conserved enzyme. This article will review the recent results obtained in this field.

Amino Acid Sequence↗
PubMed1991

Estradiol-induced adenohypophyseal growth reaction and beta-adrenergic receptors.

The effect of administration of estradiol benzoate on beta-adrenergic receptors of rat adenohypophyseal cells was studied. Twenty days' administration of estradiol benzoate was followed by an increase of adenohypophyseal weight and a decrease in specific binding of 3H-dihydroalprenolol (3H-DHA). In contrast to thyroid hormone treatment which induced an increase in 3H-DHA binding, thyroid hormone treatment decreased both the growth reaction and the reaction of beta-adrenergic receptors after estradiol. Although the relationship between the adenohypophyseal receptors and the growth reaction is unclear, changes in beta-adrenergic receptors after hormonal therapy can be one of pathophysiological conditions that may influence this reaction.

Animals↗
PubMed1991

The effect of experimental hyperthyroidism on renal and adrenal weight increase in mice.

The mouse kidneys are enlarged after the administration of thyroxine and this influence is not mediated through androgens. The administration of thyroxine increased the weight of the adrenals and the level of plasma corticosterone. Besides the direct effect of the thyroid hormones on the kidney, our findings indicate that the excess of triiodothyronine and thyroxine stimulates the activity of adrenals indirectly and evokes hyperadrenocorticism which could be related to the action of adrenal steroids on kidney function and kidney growth. In accordance with the above mentioned hypothesis it has been shown that aminoglutethimide, a potent blocker of adrenal steroidogenesis, decreases the level of plasma corticosterone and inhibits the enlargement of the kidney in hyperthyroid mice in spite of the high serum thyroxine values.

Adrenal Glands↗
PubMed1990

[Metamorphosis today].

In conjunction with the 100th anniversary of birth of the Czech physiologist V. Laufberger who discovered in 1913 the possibility to induce metamorphosis in neotenous larvae of axolotls by feeding them with thyroid gland, the author gives an account on the development of knowledge regarding metamorphosis in amphibia. He analyzes the participation of endocrine glands, in particular thyroid hormones and prolactin. Special attention is devoted to mechanisms leading to resorption of the tail in tadpoles, i. e. the activation of lysosomal enzymes due to the action of thyroid hormones. Prolactin has an inhibitory effect on metamorphosis. An important part is obviously played by deiodination of the prohormone thyroxine in target tissues to active triiodothyronine. Recently it was demonstrated that during metamorphosis a significant role is played by apoptosis (controlled non-inflammatory absorption of superfluous cells).

Ambystoma↗
PubMed1990

Preferential accumulation of radioactivity in rat kidneys after the administration of 125I-labelled Fab antidigitalis antibodies.

125I-labelled Fab antidigitalis antibodies were administered i.p. to rats, whose organs were removed 20 h later and examined for radioactivity. Maximum radioactivity was found in the thyroid region, followed by the kidneys, liver, adrenals, heart, skeletal muscle and brain. The radioactivity of kidneys was greater than in any of the other organs except the thyroid, where it probably resulted from the uptake of radioiodine, released from the antibodies. After injection of Na125I there was no difference between the kidneys and the liver. In kidney homogenates, radioactivity was present both in the 100,000xg pellet and in the supernatant. The possibility of accumulation or production of the endogenous digitalis-like factor in the kidneys is discussed.

Animals↗
PubMed1990

Increased number of beta-adrenergic receptors on cells of the rat adenohypophysis after thyroid hormone administration.

The authors studied the effect of administration of thyroid hormones on the beta-adrenergic receptors of rat adenohypophyseal cells. The administration of triiodothyronine and thyroxine was followed by an increase in specific binding for 3H-dihydroalprenolol. No significant differences were found in cyclic adenosine monophosphate levels before and after isoprenaline stimulation. The significance of changes in these receptors for the hyperplastic reaction after oestrogens is discussed with reference to the inhibitory effect of the thyroid hormones on hyperplasia of the adenohypophyseal cells after the administration of oestradiol.

Animals↗
PubMed1989

[Increased urinary excretion of neopterin in patients with Graves-Basedow disease].

In 12 patients with Graves'-Basedows' disease treated with carbimazole, the mean urinary neopterin, excretion (indicator of stimulation of cellular immunity) was 757.17 +/- 184.17 (95% confidence limit) mumol/mol creatinine with a range of 367-1420. In 12 healthy subjects of matching age and sex who served as controls the mean excretion was 422.0 +/- 96.38 (range 115 to 711, p less than 0.01). It cannot be ruled out that this increase is due to the immunomodulating action of carbimazole.

Biopterins↗