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Biomedical subjects

A Meier

Publications and source records attributed to A Meier.

At least 91 records · Page 5Linked to original sources
PubMed1981

Catecholamines, renin, aldosterone, and blood volume during chronic minoxidil therapy.

Several pressor factors were studied before and during chronic minoxidil therapy (median dose 27.5 mg/day) in 16 patients with hypertension that was refractory to conventional drugs. Following treatment with minoxidil and intensified diuretic therapy, blood pressure was decreased markedly; pulse rate, body weight, plasma volume, plasma aldosterone and epinephrine levels were not significantly altered, while plasma renin activity tended to be increased. Supine and upright plasma norepinephrine concentrations were increased by 140 (P less than 0.005) and 50% (P less than 0.05), respectively, but no significant change in urinary norepinephrine excretion was apparent. The latter parameter may not be a close index of sympathetic activity in patients with severe hypertension treated with minoxidil. While a search for underlying pheochromocytoma is always indicated in refractory hypertension, it appears mandatory to evaluate plasma catecholamines prior to or following discontinuation of treatment with minoxidil, to avoid a wrong diagnosis of pheochromocytoma.

Aldosterone↗
PubMed1981

Relationship between plasma catecholamines and urinary catecholamine excretion rates in normal subjects and certain diseased states.

Relationships between plasma norepinephrine (PNE) or epinephrine (PE) and urinary norepinephrine (UNE) or epinephrine (UE) excretion rates were studied in 37 normal subjects, 39 patients with benign essential hypertension, 23 with unilateral renal hypertension, and 20 with bilateral renal disease (serum creatinine 2.3 +/- 2.6 mg/100 ml). measurements were also performed after 6 weeks of diuretic treatment in 27 normal subjects and all patients with essential hypertension. In the untreated state, PNE and UNE values were generally normal in essential or unilateral renal hypertension; PNE tended to be decreased in diabetics and increased in bilateral renal disease. Diuretic treatment caused a tendency for slightly increased PNE and UNE. UNE correlated significantly with supine PNE or upright PNE or their mean value, and this relationship appeared to be comparable between untreated normal subjects and the various patients groups, except for a tendency for slightly higher PNE at given UNE values in bilateral renal disease. No significant correlations between UE and PE were apparent in the normal subjects or patient groups. These data demonstrate a dissociation of UE from PE levels. In contrast, UNE is an approximative index of PNE, and this relationship appeared to be generally unaltered in essential or unilateral renal hypertension. In patients with bilateral renal disease the slight shift of this relationship indicates that consideration of renal function is necessary for interpretation of NE levels.

Adult↗
PubMed1981

Diuretic treatment and serum lipoproteins: effects of tienilic acid and indapamide.

Treatment with the commonly used diuretic, chlorthalidone, has previously been found to increase the serum low-density-lipoprotein cholesterol (LDL-C) fraction. Therefore, the effects of two new agents, tienilic acid (a combined diuretic-uricosuric) and indapamide on serum lipid and lipoprotein levels were assessed. Six weeks of treatment with tienilic acid, 250 mg/day, markedly decreased serum uric acid and significantly increased LDL-C and triglycerides in 16 men. In contrast, indapamide 2.5 mg/day, had no apparent influence on serum lipids or lipoproteins in 18 men.

Diuretics↗
PubMed1981

Chronic treatment with the new potent vasodilator Ro 12-4713 in moderate to severe hypertension: effects on blood pressure, endocrine function, sodium and plasma volume.

The antihypertensive efficacy and endocrine profile of the new antihypertensive agent, Ro 12-4713, were evaluated in 23 patients (17 men and 6 women) with moderate to severe arterial hypertension. Following addition of Ro 12-4713 to pre-existing therapy with diuretics and beta-blockers or sympatholytics, blood pressure in most of the patients was normalized within one month by a daily dose of 60 to 120 mg. Heart rate was only slightly increased. Orthostatic hypotension was not observed. Weight gain or oedema formation occurred in 14 patients within the first four weeks, but could be controlled satisfactorily by intensified diuretic therapy. Increased hair growth occurred in most of the patients. After a mean duration of treatment of 2.8 months, plasma volume and plasma and urine sodium were unaltered, and plasma potassium was slightly decreased. Plasma renin activity was doubled, whereas plasma aldosterone concentrations were unaltered. Plasma norepinephrine levels were high before and increased only slightly during chronic Ro 12-4713 treatment, whereas urinary norepinephrine excretion was unchanged. Plasma and urinary epinephrine were unaltered by Ro 12-4713. Ro 12-4713 appears to be a potent vasodilator for the combination treatment of hypertension in men.

Adult↗
PubMed1981

Beta-receptor-blocking agents may reverse or prevent diuretic-induced increases in serum low-density lipoprotein cholesterol.

1. The effect of treatment with a thiazide-like diuretic alone or combined with a beta-adrenoceptor blocker on serum lipoproteins was investigated in 35 patients with essential hypertension. 2. In group I (18 patients), serum low-density lipoprotein cholesterol was increased (P less than 0.001) during monotherapy with chlorthalidone (100 mg/day) but not during combined chlorthalidone--beta-blocker therapy. 3. This tendency was similar in subgroups studied with an inverse sequence of drug administration. In subgroup IA (11 men), a 22% increase (P less than 0.01) in low-density lipoprotein cholesterol after 6 weeks of chlorthalidone was reversed after use of a beta-blocker as well as chlorthalidone; in subgroup IB (five men, two post-menopausal women), low-density lipoprotein cholesterol was increased by 41% (P less than 0.05) above placebo values 6 weeks after withdrawal of the beta-blocker from combination therapy. 4. In group II (18 men), low-density lipoprotein cholesterol was increased by 13% (P less than 0.025) after 4 weeks of monotherapy with clopamide (5 mg/day) but restored to control levels 4 weeks after addition of pindolol (10 mg/day). 5. No significant changes occurred during any treatment phase in high-density lipoprotein cholesterol. 6. Certain beta-receptor blocking agents may prevent or reverse diuretic-induced increases in serum low-density lipoprotein cholesterol.

Adolescent↗
PubMed1981

Correction of altered noradrenaline reactivity in essential hypertension by indapamide.

Fourteen patients with untreated mild to moderate essential hypertension had on average an abnormally high cardiovascular reactivity to exogenous noradrenaline and angiotension II, while plasma noradrenaline, renin activity, exchangeable body sodium, and blood volume were normal. Treatment with a low dose of indapamide (2.5 mg/day) for six weeks decreased blood pressure by 10% in these hypertensive patients but not in 13 normal control subjects. Plasma or blood volume and exchangeable sodium were not changed significantly; nevertheless, the latter, and body weight, tended to be decreased slightly. Though a mild reduction in extracellular sodium in both normal and hypertensive subjects appears possible, it may not per se fully explain indapamide's blood pressure-lowering effect in essential hypertension. Indapamide induced a mild decrease in angiotensin II pressor responsiveness in normal or hypertensive subjects, but a possible depressor influence from this change was probably antagonised by a concomitant pronounced increase in plasma renin activity. In hypertensive patients, the abnormally high noradrenaline reactivity was corrected by indapamide without an accompanying increase in endogenous plasma noradrenaline levels. Indapamide-induced changes in blood pressure correlated with those in noradrenaline pressor dose. It was concluded, therefore, that indapamide may decrease blood pressure in essential hypertension at least in part by lowering an abnormally high cardiovascular noradrenaline reactivity without causing an equivalent increase in adrenergic nervous activity.

Adolescent↗
PubMed1980

Norepinephrine clearance and pressor effect in normal and hypertensive man.

Whether and to what extent the sympathetic nervous system participates in the development of essential hypertension has remained largely unclear. The role of the adrenergic effector - cardiovascular response axis in the pathogenesis of essential hypertension was investigated by combined analysis of blood levels, total plasma clearance and cardiovascular pressor effects of norepinephrine (NE). Measurements of plasma NE and blood pressure were performed before, during and after an intravenous infusion of NE at stepwise increasing rates in approximately age and sex-matched groups of 28 normal subjects and 35 patients with essential hypertension. The threshold of the pressor effect of NE was lower in hypertensive than in normal subjects (20 +/- 10 vs. 42 +/- 26 ng/kg min; P < 0.001); but the slope of the dose - resonse curve and basal endogenous plasma NE were in the average similar. Total plasma NE clearance estimated under steady state conditions was similar in normal and hypertensive subjects (5.3 +/- 2.5 vs. 5.4 +/- 2.31/min). NE clearance corrleated inversely with basal plasma NE in normal subjects (r = 0.57; P < 0.005). The plasma half-life of NE was about 2 min. These findings demonstrate that basal blood levels and total plasma clearance of NE during NE infusion are usually normal in essential hypertension. A low threshold of the pressor effect of NE in the presence of normal adrenergic activity may contribute to the development and/or maintenance of essential hypertension.

Adolescent↗
PubMed1980

Age-rated profile of cardiovascular reactivity to norepinephrine and angiotensin II in normal and hypertensive man.

The interrelationships among age, cardiovascular pressor reactivity to intravenously infused norepinephrine (NE) or angiotensin II, and endogenous plasma NE or renin (PRA) levels were evaluated i 31 normal subjects and 37 patients with essential hypertension. In normal subjects both angiotensin II pressor dose and PRA decreased progressively with aging. Angiotensin pressor dose correlated positively with PRA (r = 0.41, P < 0.025) and inversely with age (r = -0.46, P < 0.02). NE pressor dose and basal plasma NE were also positively correlated (r = 0.53, P < 0.005), but the two factors remained largely unchanged with aging. Findings in essential hypertension differed in certain aspects. Angiotensin II pressor dose did not correlate with either basal PRA or age; and pressor doses of NE and angiotensin II tended to be lower in some patients than in normal subjects. These findings indicate that aging is accompanied by a physiologic increase in cardiovascular reactivity to angiotensin II, probably due to a concomitant decrease in circulating renin. The dissociation between angiotensin pressor dose and PRA in essential hypertension suggests an interference from an other factor.

Adult↗
PubMed1980

Time course of C-type retrovirus expression in mice submitted to osteosarcomagenic doses of 224radium.

Virus particles with the biochemical properties of C-type retroviruses appeared transiently in bone tissues of (C3H x 101) f1 hybrid mice early after treatment with 224 Radium; such particles were then again detected in the bones of the irradiated animals at the onset of osteosarcoma formation and in the osteosarcomas. Antibodies against a murine retrovirus isolated from a 224 Ra-induced osteosarcoma were produced and detected in the serum of the 224 Ra-treated animals within a month after treatment began. The antibody levels plateaued to a maximum after about 2 months and remained elevated until the tumors started to develop. The antibody concentration in the serum of these irradiated animals decreased then progressively to reach levels similar to those observed in untreated controls. It thus appears that the imminence of osteosarcoma development can be predicted by monitoring the anti-C-type virus antibody levels in the serum of the irradiated mice. These experiments also strongly suggest that treatment with 224Radium induces expression of endogenous viruses in the animals.

Animals↗
PubMed1980

[Comparison of oral diazoxide and minoxidil in refractory hypertension].

The efficacy and side effects of two potent vasodilatators, namely diazoxide and minoxidil given orally, were compared in 11 patients who had hypertension refractory to conventional drug treatment. The latter included diuretics, betablockers and/or sympatholytics, and either dihydralazine or prazosin. In a crossover approach, dihydralazine and prazosin were withdrawn and replaced by diazoxide or minoxidil. In nine patients the diazoxide phase preceded the minoxidil treatment, while in two it followed minoxidil treatment. Before introduction of the more potent vasodilators blood pressure averaged 181/107 mm Hg in the supine and 161/103 mm Hg in the upright position. Both, oral diazoxide (median dose 400 mg/d( and minoxidil (medium dose 17.5 mg/d) produced similar decreases (p < 0.02) in mean arterial pressure (-15%) in the supine and (-11 vs. -12%) in the upright position. They caused a comparable tendency for sodium retention and weight gain which could be satisfactorily controlled with increased diuretic therapy, except in one patient. Hypertrichosis occurred with both drugs, but tended to be somewhat milder with diazoxide. Electrocardiograms remained generally unchanged. Plasma glucose levels were increased during diazoxide treatment in six patients necessitating interruption of this therapy in four patients. It is concluded that the antihypertensive potency and most side effect of orally administered diazoxide are comparable to those of minoxidil, except for diazoxide-related hyperglycemia which may limit the use of this substance.

Blood Glucose↗
PubMed1980

Increased serum low-density lipoprotein cholesterol in men treated short-term with the diuretic chlorthalidone.

The effect of the diuretic chlorthalidone (100 mg/day for 6 weeks) on serum lipoproteins was evaluated in 37 subjects. In 19 men with essential hypertension (aged 41 +/- 3 yr), 8 normal men (26 +/- 3 yr), or all of these men considered together, chlorthalidone significantly increased serum low density lipoprotein--cholesterol (LDL-C) by 20% (p less than 0.05 to less than 0.01). There was also a tendency for increased LDL-C in seven postmenopausal women (+/- 15%) but not in three premenopausal women with essential hypertension. High density lipoprotein--cholesterol was not significantly changed in hypertensive women or normal men and decreased slightly (p less than 0.05) in hypertensive men. Apolipoproteins A-I, A-II, and B were not changed significantly in women or men. Diuretic-induced lipoprotein alterations were not associated with altered plasma volume and unrelated to variations in serum potassium, glucose, insulin levels, blood pressure, and body weight. Short-term diuretic therapy with chlorthalidone may increase serum LDL-C in young or middle-aged men with normal or high blood pressure.

Adolescent↗