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Biomedical subjects

A Studer

Publications and source records attributed to A Studer.

At least 55 records · Page 3Linked to original sources
PubMed1984

Does amiodarone affect heart rate by inhibiting the intracellular generation of triiodothyronine from thyroxine?

The hypothesis that the antiarrhythmic drug amiodarone slows down the heart rate by its inhibitory action on the intracellular conversion of thyroxine (T4) to 3,5,3' triiodothyronine (T3) was investigated. For this purpose we compared the effect of amiodarone with that of another potent inhibitor of the T4----T3 conversion, i.e. the radiographic contrast medium iopanoic acid, on the heart rate of unanaesthetized guinea-pigs. Both amiodarone and, to an even greater extent, iopanoic acid induced an increase in serum 3.5',3' triiodothyronine (reverse T3), indicating effective inhibition of T4----T3 conversion. Both amiodarone and iopanoic acid were accumulated in the liver and in the heart (measured as iodine). While amiodarone induced bradycardia, iopanoic acid did not change the heart rate. Supraphysiological amounts of exogenous T3 reverted the amiodarone induced bradycardia to near normal values. A comparable effect was observed with isoprenaline. The intracellular inhibition of the T4----T3 conversion is not the ultimate mode of the action of the amiodarone effect on heart rate. It is thought that amiodarone interacts with T3 at its receptor or somewhere later along the pathway from the T3-receptor interaction to the final effect of T3 on heart rate.

Amiodarone↗
PubMed1983

Effect of pindolol and propranolol on plasma renin and aldosterone in patients with renal allograft.

To investigate the effect of propranolol and pindolol on renin and aldosterone secretion, blood samples of 12 nephrectomized kidney transplant recipients were taken after 1 hour in supine position and 30 and 60 minutes after posture change. This procedure was repeated after 4 days under pindolol (3 X 5 mg/day) or propranolol (4 X 40 mg/day). Both pindolol and propranolol suppressed the significant orthostatic rise of plasma renin activity (PRA) seen without medication. Pindolol increased basal PRA markedly, whereas basal PRA under propranolol was the same as without betablockers. Plasma aldosterone (PA) showed significant orthostatic rise under all conditions and thus did not parallel PRA under betablockers. Suppression of PRA response to posture change by betablockers indicates that circulating catecholamines may be involved in orthostatic PRA regulation. The intrinsic sympathetic activity of pindolol results in an increase of basal PRA. In nephrectomized renal transplant recipients, postural PA changes do not seem to be triggered by PRA.

Adult↗
PubMed1982

[Weight reduction and blood pressure].

112 patients (78 hypertensives and 34 normotensives) received guidance from a specially trained dietitian on a low-calorie diet. During a mean control period of 10.8 months with a comparable number of visits in each group, the following results were observed: 51% (n = 40) of hypertensive patients achieved a significant weight reduction. In 28% (n = 22) antihypertensive medication was constant and in 23% (n = 18) this medication was reduced or withdrawn. 37% (n = 29) showed no significant changes in body weight or blood pressure and 12% (n = 9) dropped out. In 22 patients a weight reduction of 8.5 kg with a significant fall in blood pressure from 156/99 to 137/90 mm Hg was observed. In 18 hypertensives a weight reduction of 8.5 kg allowed reduction or withdrawal of antihypertensive medication with blood pressure remaining unchanged (139/91 vs. 135/90 mm Hg). Similar results were achieved in 34 normotensive obese patients: 59% (n = 20) had significant weight reduction, 32% (n = 11) no significant reduction in weight or blood pressure, and 9% (n = 3) dropped out. 20 patients with a reduction of 9 kg showed a significant fall in blood pressure from 132/84 to 123/80 mm Hg. The results demonstrate the favourable effect of weight reduction on blood pressure. The time-consuming nature of the frequent and intensive checks should, however, be borne in mind.

Adult↗
PubMed1982

[Blood pressure, renin angiotensin aldosterone system and other cardiovascular risk factors in children of essential hypertensives (author's transl)].

In the present study, blood pressure, the renin angiotensin aldosterone system, and other cardiovascular risk factors, such as glucose, cholesterine, and triglycerides, were investigated in 294 offspring of essential hypertensives (5-34 years) and in 122 children of normotensive parents (5-34 years). Offspring of essential hypertensives showed statistically significant higher systolic and diastolic blood pressure values than those of normotensive parents (p less than 0.003, less than 0.005, respectively). Furthermore, in children of hypertensive parents a statistically significant higher body weight and body mass index than in controls could be observed (p less than 0.006, less than 0.001, respectively). With the exception of statistically significant, lower mean supine plasma aldosterone values (p less than 0.02) in children of hypertensive parents, no major differences between the two groups were seen in stimulated aldosterone, supine and stimulated plasma renin activity, and plasma cortisol. Furthermore, in the present study, 41 hypertensive parents, 65 (normotensive) spouses of hypertensives, and 47 (normotensive) parents of control children were investigated. As expected, hypertensive parents showed statistically significant higher blood pressure values than parents of control children and their spouses (p less than 0.001). Interestingly, hypertensive parents had not only a higher body mass index than control parents but also than their spouses (p less than 0.01 and less than 0.02, respectively). These findings support a genetic disposition as being the underlying cause of higher body weight in hypertensives and make it less probable that a higher food intake in hypertensive families is responsible for this phenomenon. The results of the present study indicate that early body weight control in children of hypertensive parents may be an important contribution to the prevention of hypertension.

Adolescent↗
PubMed1982

Long-term experience with captopril in severe hypertension.

1 The long-term effect of the converting-enzyme inhibitor captopril was investigated in 76 patients with various forms of severe hypertension, most cases being resistant to a standardised triple therapy (100 mg hydrochlorothiazide or 80-500 mg frusemide; 320 mg propranolol; and 200 mg hydralazine). 2 In each of the three groups examined (essential, renovascular, and renal parenchymatous hypertension) captopril led to a prompt and sustained reduction in systolic and diastolic blood pressure. Up to an observation time of 2 1/2 years patients with renovascular hypertension showed a more pronounced fall in mean diastolic blood pressures than those with essential hypertension. About 90% of all patients required a diuretic and a substantial percentage of patients needed propranolol as a third drug. 3 The most frequent side effects were skin manifestations, taste disturbances, dizziness, and non-productive cough. Serious adverse effects were rare and included one case of leucopenia and one of the nephrotic syndrome, both of them reversed after withdrawal of captopril. Further analysis showed that side effects occurred mainly in patients with impaired kidney function receiving relatively high dosages of captopril (greater than 200 mg/day). 4 Our results show that captopril is a very potent blood-pressure-lowering agent in severe hypertension, especially in cases with renovascular hypertension.

Adult↗
PubMed1981

Renal venous renin activity in various forms of curable renal hypertension.

The diagnostic and predictive value of renal venous renin determinations was investigated in 73 patients who had various forms of hypertension associated with unilateral renal disease and who were operated upon. Patients with fibromuscular hyperplasia showed a markedly higher cure rate than cases with arteriosclerotic renal artery stenosis (64% vs. 25%) and were less frequently not improved (4% vs. 12%). Patients with unilateral (non-vascular) small kidney and patients with unilateral hydronephrosis showed comparable high cure rates (53% and 50%, respectively), whereas in no patient with a unilateral renal cyst did postoperative blood pressure return to normal. In the present study no statistically significant correlation was found between postoperative pressure reduction and PRA-ratios in either the whole group of patients or in the various subgroups. A negative PRA-ratio (less than or equal to 1.4) was found in 36% of all cured patients. In particular, cured patients with fibromuscular hyperplasia showed a high percentage (38%) of falsely negative tests. As expected, characteristic differences were observed in simple clinical data between cured and improved patients. Patients with normal postoperative blood pressure were significantly young (34.7 +/- 13.6 years) than improved cases (47.3 +/- 10.8 years; P less than 0.001) and cured patients showed lower preoperative blood pressure values (192 +/- 29/119 +/- 15) than improved ones (214 +/- 31/126 +/-117 mm Hg). Thus our results document a limited prognostic value of renal venous renin determination in patients with hypertension due to unilateral renal disease.

Adolescent↗
PubMed1980

[Captopril in treatment-resistant hypertension (author's transl)].

26 patients with severe hypertension (10 essential, 9 renal parenchymatous, 7 renovascular) and a mean age of 42 years were treated with the new oral converting enzyme inhibitor captopril (SQ 14225). During the initial phase with a standardized triple therapy (STT) consisting of propranolol (maximum 320 mg/day), hydralazine (maximum 200 mg/day) and hydrochlorothiazide (maximum 100 mg/day) or furosemide (maximum 250 mg/day) mean systolic and diastolic blood pressure values remained almost unchanged (184 +/- 32/111 +/- 17 mm Hg to 179 +/- 34/112 +/- 19 mm Hg), indicating true therapy resistance to conventional antihypertensive therapy. After discontinuing each antihypertensive agent captopril was then titrated from 3 X 25 mg/day to a maximum of 4 X 150 mg/day. Mean systolic and diastolic blood pressure values 2, 4, 8, and 16 weeks after starting captopril were 154/95, 155/97, 149/93 and 143/91 mm Hg. The corresponding mean captopril doses were 242, 280, 325 and 299 mg daily. During captopril medication mean systolic and diastolic blood pressure values were significantly lower (p less than 0.05 to p less than 0.005) than during STT. Throughout the observation period of 16 weeks only 15% of the cases were on monotherapy with captopril whereas 62% needed the addition of a diuretic (hydrochlorothiazide or furosemide). In 23% of the cases even the combination of captopril and diuretic was insufficient and thus propranolol was added as a third drug. The side effects observed were 1 case with renal water and fluid retention and with reversible skin rash and 1 with pruritus. The results demonstrate that captopril has good blood pressure lowering activity in patients with treatment-resistant hypertension. However, in the majority of our cases the addition of a diuretic was necessary. Finally, some patients required a beta-blocker as a third drug.

Adult↗
PubMed1980

Lateralization procedures in primary aldosteronism.

The diagnostic validity of adrenal isotopic scanning, adrenal venous aldosterone, adrenal phlebography and computed abdominal tomography (CT) was studied in 44 patients with primary aldosteronism. In all patients the diagnosis was confirmed by surgery (unilateral adrenal adenoma n = 32, bilateral adrenal hyperplasia n = 12). Both adrenal scintiscan, adrenal venous aldosterone and CT allowed in a comparable high percentage of patients (71%0 the exact classification of the adrenal lesion(s), whereas adrenal phlebography could distinguish adenoma from hyperplasia in 57%. Marked differences between the lateralization procedures, however, were observed in predicting incorrect preoperative indentification: adrenal scintiscan 29%, adrenal venous aldosterone 3%, adrenal veno-graphy 6% and CT 0%. Finally, the percentage of patients in whom no differentiation between the two main subgroups of primary aldosteronism could be obtain varied between 0% with adrenal isotopic scanning and 37% with adrenal phlebography (CT 29% and adrenal venous aldosterone 26%). Both scintiscan and adrenal venous aldosterone were not improved by the administration of dexamethasone. Our findings document that adrenal venous aldosterone determinations, adrenal isotopic scanning and computed tomography are equally valid in differentiating unilateral adenoma from bilateral adrenal hyperplasia in primary aldosteronism. However, adrenal scintiscan is hampered by a relative high percentage of incorrect results independant whether dexamethasone was used or not. Contrary, adrenal venous aldosterone and computed tomography seemed to have no or only a minor risk in assuming an incorrect classification of the adrenal lesion(s).

Adenoma↗
PubMed1980

[Prevalence of hypertension and borderline hypertension in students. Comparison with a non-student group].

A blood pressure detection program was conducted at the University of Zurich in June 1978. Three consecutive blood pressure measurements using random-zero mercury sphygmomanometers (n = 4) were performed in 1364 students and 440 other subjects by 8 different investigators. Height and body weight were also measured and used to calculate the body mass index (Quetelet index). Personal history, physical activity, smoking and dietary habits were analyzed with the aid of a questionnaire. In comparison to initially measured values, there was a statistically significant decrease in systolic and diastolic pressure readings as the trial proceeded (p less than 0.001). Based on the mean value of all three measurements, hypertension was observed in only 1.7% of the male and 0.9% of the female students. In the other subjects covered by the trial the comparable values were 7.9% in males and 4.5% in females. The true prevalence of hypertension (addition of those persons with normotensive blood pressure values and simultaneous antihypertensive therapy) was 1.9% in male and 1.1% in female students, whereas 12.0% of the male and 8.5% of the female non-students suffered from hypertension. The prevalence of border-line hypertension (mean value of all three tests) was 7.4% in male and 3.0% in female students. Corresponding values for the other subjects tested were 18.7% (males) and 11.6% (females).

Adult↗