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Biomedical subjects

I Varga

Publications and source records attributed to I Varga.

At least 109 records · Page 6Linked to original sources
PubMed1991

Dissociation of plasma atrial natriuretic peptide responses to upright posture and furosemide administration in patients with normal-, low renin essential hypertension and primary aldosteronism.

Plasma levels of atrial natriuretic peptide (ANP) were measured in patients with normal renin essential hypertension (n = 12), low renin essential hypertension (n = 11) and primary aldosteronism due to aldosterone producing adenoma (APA, n = 8) and idiopathic hyperaldosteronism (IHA, n = 3) after overnight rest in the supine position and after 4 h upright posture and furosemide administration. Plasma renin activity (PRA) and aldosterone (Aldo) levels were also determined. Compared to normal renin essential hypertension (33.6 +/- 2.2 pg/ml), basal plasma ANP was significantly higher in low renin essential hypertension (66.8 +/- 6 pg/ml), IHA (54.1 +/- 6.3 pg/ml) and APA before (62.4 +/- 4.9 pg/ml) but not after adrenal surgery (22 +/- 3 pg/ml). After upright posture and furosemide administration plasma ANP was decreased (p less than 0.01) in patients with low renin and, less markedly, with normal renin essential hypertension, however not in IHA and APA. In about half of the patients with low renin essential hypertension, unchanged PRA after upright posture and furosemide administration was associated with increased plasma Aldo and decreased ANP levels. We conclude that (i) the relatively high basal plasma ANP levels in low renin essential hypertension, IHA and APA may reflect the presence of volume expansion in these patients; (ii) the hormonal responses to upright posture and furosemide administration in patients with normal and low renin essential hypertension may indicate a counterregulatory role of ANP during activation of the renin-angiotensin-aldosterone system; (iii) the high plasma ANP, which is unresponsive to upright posture and furosemide administration, in patients with APA and IHA may be a potentially interesting new finding whose pathophysiological significance remains to be established.

Adult↗
PubMed1991

Thrombosis prophylaxis with subcutaneous heparin Ca injection in the course of caesarean sections.

Subcutaneous low-dose Heparin Ca injections were given as prophylactic treatment to 31 women who were candidates for Caesarean section and were at high risk of thrombo-embolism. Postoperative deep vein thrombosis or pulmonary embolism did not occur in the treated cases. Local or systemic haemorrhages or other reactions were not observed. The controlled haematological parameters changed as expected. According to the opinion of the authors Heparin Ca may be successfully used for the prevention of the postoperative complications of Caesarean section.

Adult↗
PubMed1990

Thyrotropin-releasing hormone increases plasma atrial natriuretic peptide levels in human.

The effect of thyrotropin-releasing hormone (TRH) on plasma atrial natriuretic peptide (ANP), TSH, prolactin, cortisol and aldosterone levels in 26 patients with normal pituitary and thyroid gland function was examined. Bolus iv injection of 200 micrograms TRH produced, between 0 and 60 min, a significant gradual rise of plasma ANP concentrations from 30.4 +/- 2.3 to 54.8 +/- 6.4 pg/ml (mean +/- SE). Plasma prolactin and TSH concentrations increased four- and six-fold of basal values with peak responses at 15 and 30 min, respectively, whereas plasma cortisol and aldosterone concentrations remained unchanged after the drug treatment. The patients had no significant changes in blood pressure or pulse rate. We conclude that there may be indirect mechanism(s) which result in increased ANP levels after TRH administration.

Adult↗
PubMed1990

An antioxidant drug, silibinin, modulates steroid secretion in human pathological adrenocortical cells.

Because human adrenocortical cells from different adrenal disorders exhibit pathologically altered corticosteroid synthesis, and free radical mechanisms may induce pathological changes in the activities of corticosteroid biosynthetic enzymes (cytochrome P-450), we examined the effect of an antioxidant, silibinin, on basal and ACTH-stimulated secretion of several corticosteroids in isolated adrenal cells from an aldosterone-producing adenoma, atrophied adrenal tissues surrounding the adenoma, and hyperplastic adrenals from Cushing's syndrome. In the presence of a high concentration (100 mumol/l) of silibinin, variably diminished secretion of basal aldosterone, corticosterone, cortisol, 18-OH-corticosterone and 11-deoxycorticosterone was found. In contrast, the addition of 0.01 mumol silibinin/l, which failed to produce a clear effect on basal corticosteroid secretion, resulted in a potentiation of ACTH-stimulated secretion of several corticosteroids in the adenomatous and hyperplastic adrenocortical cells. These results suggest that the dose-dependent dual effect of silibinin on corticosteroid secretion may be attributed to corresponding changes in the activities of cytochrome P-450 enzymes, and that stimulation of ACTH-induced corticosteroidogenesis by silibinin is presumably due to the antioxidant property of the drug.

18-Hydroxycorticosterone↗
PubMed1988

Atrial natriuretic peptide directly inhibits corticosteroid biosynthesis in human aldosterone-producing adenoma.

The effect of human atrial natriuretic peptide (hANP) on aldosterone, 18-OH-cortisterone, corticosterone, deoxycorticosterone, and cortisol secretion was examined in isolated human aldosteronoma cells from five patients with primary aldosteronism. hANP exerted a nearly identical inhibitory action on basal secretion of each of these steroids and antagonized also the stimulating effects of ACTH, serotonin, metoclopramide and vasoactive intestinal polypeptide. The results suggest that in human aldosteronoma cells hANP may be a non-selective inhibitor of corticosteroid biosynthesis and that the site of inhibition of steroidogenesis may be localized to the early pathway of steroid biosynthesis.

Adenoma↗
PubMed1987

Immunohistochemical localization of atrial natriuretic peptide in primary aldosteronism.

Using the immunoperoxidase method with specific antibody, we examined the presence of atrial natriuretic peptide (ANP) in adrenal tissues of a patient with primary aldosteronism and those derived from a patient with Cushing's syndrome. We found cells immunopositive for ANP in primary aldosteronism but not in Cushing's syndrome. In primary aldosteronism, we noted positively stained cells mainly but not exclusively in the adenomatous tissue. These results demonstrate for the first time the presence of immunoreactive ANP in adrenal tissues of a patient with primary aldosteronism and suggest that adrenal ANP may have potentially important impacts on aldosterone secretion in this disorder.

Adrenal Glands↗
PubMed1985

Riboflavin (vitamin B2) treatment of neonatal pathological jaundice.

The effect of traditional blue-light and riboflavin combined with blue-light was compared in newborns affected by ABO incompatibility, admitted for exchange transfusion. During the period of preparation for the intervention 14 patients were treated with blue light alone and 14 patients with riboflavin combined with phototherapy. A single dose of 10 mg/kg riboflavin was administered intravenously. The duration of treatment was three hours in both groups. The effect of phototherapy was markedly enhanced by the additional riboflavin, by the end of the 3-hour period a significant fall of serum bilirubin was demonstrated in the 14 patients treated with blue light and riboflavin while in the patients treated with phototherapy alone the bilirubin level continued to rise. There was no difference in the activity of the antioxidant enzymes superoxide dismutase and catalase, and in lipid peroxidation between the groups.

ABO Blood-Group System↗
PubMed1984

ACTH sensitivity of isolated human pathological adrenocortical cells: variability of responses in aldosterone, corticosterone, deoxycorticosterone and cortisol production.

In vitro aldosterone, deoxycorticosterone, corticosterone and cortisol production of human adrenocortical cells derived from adenomas (Conn's syndrome, Cushing's syndrome), from hyperplastic adrenals (Cushing's syndrome) and from adrenals surrounding aldosteronoma are described. Cells from adenomas causing either Cushing's syndrome or Conn's syndrome harboured the highest basal and ACTH-stimulated corticosteroid production. Adrenocortical cells derived from micronodular hyperplasia causing Cushing's syndrome and cells from cortisol producing adenoma displayed predominantly cortisol and corticosterone secretion both under basal conditions and following stimulation with ACTH. Aldosteronoma cells showed highly variable aldosterone, deoxycorticosterone, corticosterone and cortisol response to ACTH. However, in aldosteronoma cell suspensions, the basal and ACTH-stimulated ratios of aldosterone to cortisol were increased when compared to ratios of steroids produced by cells from other adrenal tissues. Chronic treatment with spironolactone of patients with Conn's syndrome before surgery was associated with a decreased ratio of aldosterone to corticosterone, revealing that 18-hydroxylase in aldosteronoma cells may be inhibited during long-term therapy. Non-tumorous cells isolated from adrenals surrounding aldosteronoma displayed less aldosterone prior to and after stimulation with ACTH than aldosteronoma cells.

Adenoma↗
PubMed1982

Large-scale management systems and parasite populations: coccidia in rabbits.

Broiler rabbit production has become an important branch of animal protein and fur production, not only in the traditionally rabbit breeding and consuming countries, but recently in many other countries of the world. The profitability of the rabbit industry is dependent primarily on the good feed conversion. Aspects of this include factors such as morbidity and mortality of infections, adequate knowledge and fulfilment of both accommodation and nutritional requirements, appropriate breeding systems, etc. There is much controversy about the role of coccidia in the losses of intensified rabbit breeding enterprises. There is no doubt about the significance of Eimeria stiedai which may cause condemnation of large amounts of liver as a result of infection in rabbit colonies of small holders. However, this parasite is rare in large scale rabbit farms. In the latter, intestinal coccidiosis is most frequently--although not invariably--incriminated either as a primary or more often as a predisposing factor of intestinal enteropathies causing severe mortality, mainly in the early post-weaning period. The ability to isolate and maintain species of Eimeria in specific pathogen-free (SPF) rabbits has made it possible to characterize them, such as the most pathogenic E. intestinalis and E. flavescens: the pathogenic E. magna, E. irresidua and E. piriformis; and the least pathogenic E. perforans, E. neoleporis (syn. of E. coecicola) and E. media species. Prophylactic measures are dealt with briefly, and laboratory and field trials with the currently most promising rabbit anti-coccidial drugs (Lerbek, robenidine and salinomycin) are dealt with in more detail.

Animals↗
PubMed1982

Met-enkephalin inhibits mineralocorticoid production in isolated human aldosteronoma cells.

In vitro application of the morphinomimetic met-enkephalin resulted in inhibition of mineralocorticoid production by aldosterone-producing adenomas. Aldosterone, deoxycorticosterone, and corticosterone production by adrenocortical cells isolated from aldosteronomas has been studied under basal conditions and after stimulation with ACTH-(1-24). The blocking effect of met-enkephalin on the rate of aldosterone, deoxycorticosterone, and corticosterone release was significant at a concentration as low as 10(-11) M (P less than 0.001, P less than 0.01, and P less than 0.001, respectively). Dose-dependent inhibition of steroid biosynthesis became more apparent with increasing amounts of met-enkephalin in the incubation medium (10(-11)-10(-5) M); at a concentration of 10(-5) M, met-enkephalin decreased the production of aldosterone by 45%, that of deoxycorticosterone by 51%, and that of corticosterone by 44%. Increased steroid biosynthesis stimulated by ACTH-(1-24) was also significantly blocked by met-enkephalin. In a concentration of 10(-5) M, met-enkephalin produced significant decreases in aldosterone (P less than 0.001), deoxycorticosterone (P less than 0.05), and corticosterone (P less than 0.001) production compared to the peak values obtained after stimulation with 0.85 X 10(-10) M ACTH-(1-24). These data allow us to conclude that the inhibitory effect of met-enkephalin on mineralocorticoid production exerted at the level of the adrenals might be complementary to the factor(s) thought to be involved in the regulation of adrenal steroid production, playing a role similar to that of the biogenic amines originating in the adrenal medulla and regulating the adrenal cortex by a peripheral neurohumoral paracrine mechanism.

Adenoma↗