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Biomedical subjects

W R Adam

Publications and source records attributed to W R Adam.

At least 55 records · Page 3Linked to original sources
PubMed1983

Cyproheptadine and mineralocorticoid effector mechanisms.

Cyproheptadine has recently been reported to blunt the furosemide-induced rise in PRA in normal subjects and to acutely lower plasma aldosterone levels in patients with hyperaldosteronism due to bilateral adrenal hyperplasia; both actions have tentatively been ascribed to the antiserotoninergic action of the drug. We here describe receptor studies showing cyproheptadine to occupy mineralocorticoid, but not glucocorticoid, receptors in rat and mouse kidney. On bioassay, cyproheptadine is a partial mineralocorticoid agonist/predominant antagonist.

Adrenalectomy↗
PubMed1982

Comparison of oral and intravenous radiosulfate spaces in dialysis patients.

Radiosulfate spaces were measured after intravenous and oral radiosulfate in dialysis patients. Radiosulfate spaces after oral administration were consistently higher than after intravenous administration, which gave results within the accepted normal range. The increased radiosulfate space after oral administration was due to, either delayed absorption, or sequestering of the radiosulfate in an unknown space.

Administration, Oral↗
PubMed1982

The mechanism of mineralocorticoid action of carbenoxolone.

The principal side effects of the drug carbenoxolone (Biogastrone; 18 beta-glycyrrhetinic acid sodium hemisuccinate) are sodium retention, hypokalemic alkalosis, suppressed plasma renin, and hypertension. In previous animal studies, carbenoxolone appeared not to have intrinsic mineralocorticoid activity but, rather, to enhance aldosterone action by displacing it from nonspecific binding sites. We here report studies showing that carbenoxolone has demonstrable affinity for rat kidney mineralocorticoid receptors, intrinsic mineralocorticoid activity in the adrenalectomized rat at doses consistent with its receptor affinity, and, in addition, a powerful action of amplifying the electrolyte effects of near-maximal doses of aldosterone.

Adrenalectomy↗
PubMed1982

Labetalol, beta blockers, and acute deterioration of chronic airway obstruction.

The effects on lung function of labetalol (a combined alpha and beta adrenergic receptor blocker) and three beta adrenergic receptor blockers (propranolol, atenolol, metoprolol) have been assessed in patients with chronic airflow obstruction using a double-blind trial. With the dosages used, all drugs produced an equivalent fall of blood pressure. Propranolol was the only drug that significantly increased airways obstruction (FEV1, specific airways resistance). Following salbutamol, labetalol was associated with a significantly greater improvement of airflow than either propranolol or metoprolol. On these acute studies, the order of preference for beta blocking drugs in management of hypertension in patients with obstructive airways disease, would be labetalol, (atenolol) or (metoprolol) and then propranolol.

Adrenergic beta-Antagonists↗
PubMed1982

A double-blind comparison of verapamil and labetalol in hypertensive patients with coexisting chronic obstructive airways disease.

A randomized, double-blind, cross-over trial was carried out in nine hypertensive patients with coexisting chronic obstructive lung disease to evaluate the hypotensive efficacy and safety of verapamil and labetalol. The effects on respiratory function were also assessed. Verapamil in doses of 160 mg twice daily was equally effective as 200 mg twice daily of labetalol. Labetalol significantly reduced both forced expiration volume at 1 s (FEV1) and forced vital capacity (FVC), suggesting a bronchoconstrictor effect. Verapamil was devoid of any such effect. Neither drug caused significant side effects.

Aged↗
PubMed1981

Orally active mineralocorticoid agonists and antagonists: delta 1-derivatives of aldosterone and 18-deoxyaldosterone.

The effect of delta 1 unsaturation on the oral effectiveness of a representative mineralocorticoid agonist and antagonist was investigated in an adrenalectomized rat bioassay. Dehydrogenation at the 1.2 position did not alter the qualitative nature of the mineralocorticoid activity of the parent compound. Thus delta 1-aldosterone (21,18-dihydroxy-11 beta, 18-oxido-1,4-pregnadiene-3,20-dione) retained pure mineralocorticoid agonism, and delta 1-18-deoxyaldosterone (21-hydroxy-11 beta, 18-oxido-1,4-pregnadiene-3,20-dione)demonstrated the same relative degree of predominant antagonism as 18-deoxyaldosterone (21-hydroxy-11 beta, 18-oxido-4-=pregnene-3,20-dione) itself. In each instance, receptor affinity was diminished by 1,2 unsaturation, but this effect was offset by the greater bioavailability of the delta 1 derivatives on oral administration. (Endocrinology 108: 517, 1981)

Administration, Oral↗
PubMed1981

19-Nor progesterone is a mineralocorticoid agonist.

19-Nor progesterone (19-nor P) has previously been shown to have a approximately 3-fold higher affinity for mineralocorticoid receptors than progesterone (P), its C-19 methylated parent steroid; in contrast, 19-nor aldosterone has less than 1% the mineralocorticoid receptor affinity of aldosterone. In the present study we have compared P and 19-nor P, in terms of their mineralocorticoid activity in an adrenalectomized rat urinary K+/Na+ bioassay system. Progesterone, as previously has been shown, is a mineralocorticoid antagonist with no agonist activity. In contrast, 19-nor progesterone is a full mineralocorticoid agonist, with no discernible antagonist activity. Loss of the C19 methyl is thus followed by profound changes in mineralocorticoid activity (aldosterone: agonist to inactive; progesterone: antagonist to agonist). In the light of the recent demonstration of C19 demethylation by the kidney, such changes in mineralocorticoid activity may be implicated in currently unexplained syndromes of sodium retention.

Adrenalectomy↗
PubMed1981

Significance, mechanisms and control of renal ammoniagenesis.

Ammonia is quantitatively the major buffer for hydrogen ion in the urine. Further, the excretion of ammonia can be varied by acid base status and is therefore of homeostatic importance. Acid base status exerts its effect on ammonia excretion both directly and also via an effect on renal ammonia production from glutamine. The mechanism of the effect of acid base status on glutamine deamidation and deamination is uncertain. Apart from its homeostatic role in health and disease alterations in renal ammonia production may assume pathological importance in potassium depletion and uric acid urolithiasis.

Acid-Base Equilibrium↗
PubMed1980

Hydrothorax with peritoneal dialysis: radionuclide detection of a pleuro-peritoneal connection.

Unilateral hydrothorax occurring during peritoneal dialysis is well described and has been presumed to be secondary to a pleuroperitoneal communication. Diagnosis of these communications usually requires invasive procedures. A non-invasive method of confirmation of abnormal pleuro-peritoneal communication using radionuclide scanning is outlined. The occurrence of this complication has usually meant cessation of this type of dialysis. However, this patient illustrates that continuation of peritoneal dialysis is possible.

Female↗
PubMed1979

Duration of effect of different diuretics.

Twenty-four patients with hypertension were treated with chlorothiazide, chlorthalidone, and frusemide. Each diuretic had a significant and similar antihypertensive effect. After cessation of the administration of diuretics, the antihypertensive effect persisted for a longer time with chlorthalidone than with the other two drugs. The full antihypertensive effect of chlorthalidone and chlorothiazide was still present 24 hours after the administration of the drugs was ceased, and the full effect of chlorthalidone was present 72 hours after the administration of the drug was ceased. Side effects related to a rapid diuresis were more common with frusemide. The study indicated that chlorthalidone could be given at 48-hour or 72-hour intervals, and that other diuretics may be given once daily to exert their full antihypertensive action.

Aged↗
PubMed1979

The mineralocorticoid antagonist activity of an 11 beta,18-oxidopregnane.

Removal of the 18-hydroxy group of the hemiacetal form of aldosterone transforms its activity from that of pure agonist to predominant antagonist. The 18-deoxy derivative possesses one third of the binding affinity of aldosterone for the cytoplasmic mineralocorticoid receptor of rat kidney and exhibits an approximate 2:1 antagonist to agonist ratio in both toad bladder and adrenalectomized rat bioassay systems. The promising properties of the 11 beta,18-oxidopregnane tested included very low androgen receptor affinity and approximately equal effectiveness in vitro and in vivo in displacing aldosterone from mineralocorticoid-binding sites in the rat.

Aldosterone↗