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Biomedical subjects

T Thien

Publications and source records attributed to T Thien.

At least 271 records · Page 15Linked to original sources
PubMed1983

Hemodynamic effects of isometric exercise and mental arithmetic in hypertension treated with selective and nonselective beta-blockade.

Hypertensive patients have an unfavorable pressor response to exogenous epinephrine during nonselective beta-blockade. We studied hemodynamics during epinephrine release induced by handgrip exercise and mental arithmetic to examine the clinical relevance of this phenomenon. Twenty-two hypertensive patients were examined in a double-blind crossover experiment with placebo, propranolol (240 mg daily), placebo-washout, and metoprolol (300 mg daily). Changes induced by stress tests for systolic and diastolic blood pressure, heart rate (HR), and forearm blood flow (FBF) were of the same order on both beta-blockers. Rises in HR and FBF were equally reduced by both drugs. Neither handgrip exercise nor mental arithmetic induced significant differences in reaction during selective and nonselective beta-blockade.

Adolescent↗
PubMed1983

Effects of intravenous endralazine in essential hypertension.

The effects of endralazine, administered intravenously, on blood pressure, heart rate, forearm blood flow, plasma renin activity, aldosterone, adrenaline and noradrenaline were studied in five patients with essential hypertension. Endralazine reduced peripheral vascular resistance, resulting in decrease in mean arterial pressure from 141 to 116 mm Hg and increase in heart rate from 67 to 92 beats/min. Plasma renin activity, adrenaline and noradrenaline increased significantly after endralazine infusion. All effects observed are consistent with endralazine acting as a peripheral vasodilating drug.

Adult↗
PubMed1983

Acute treatment of hypertension with slow infusion of diazoxide.

We have treated 81 patients who had hypertension with slow intravenous infusion of diazoxide (15 mg/min; 5 mg/kg of body weight). Blood pressure was reduced effectively both in patients with severe hypertension (n = 40) and in patients with a hypertensive crisis (n = 34); the decrease of mean arterial pressure (delta MAP) being -17.0% +/- 1.2% (mean +/- SEM) and -19.7% +/- 1.5%, respectively. However, the delta MAP was significantly greater in patients with preeclampsia (-26.0% +/- 3.0%). In all instances BP fell gradually and then decreased only slightly after discontinuation of the infusion. Thus, the potentially hazardous, steep, and exaggerated fall of BP, observed after bolus injections, can be avoided. Electrocardiographic signs of myocardial ischemia were seen in two patients. No other serious side effects were observed. We conclude that, even in patients with a hypertensive crisis, slow infusion is a safe and effective procedure for the reduction of BP.

Adult↗
PubMed1982

Radioenzymatic assay of plasma adrenaline and noradrenaline: evidence for a catechol-O-methyltransferase (COMT) inhibiting factor associated with essential hypertension.

During the evaluation of a modified radioenzymatic determination of plasma adrenaline and noradrenaline, it has been found that there exists a highly significant (p less than 0.001) negative correlation between the amount of radioactivity incorporated in the internal standard added to plasma and the period during which the plasma had been stored at -25 degrees C, but only in plasma from patients with essential hypertension. Plasma from normotensive persons exhibits a complete lack of correlation between these factors. The consequences of the hypertension-associated COMT-inhibiting factor for the assays' specifications are discussed and data are presented for comparison with a recently described uremia-associated COMT-inhibitor (Demassieux et al, Clin Chim Acta 115, 377--391; 1981).

Animals↗
PubMed1982

Effect of low-dose epinephrine infusion on hemodynamics after selective and nonselective beta-blockade in hypertension.

We studied hemodynamic effects of low doses of epinephrine in five hypertensive patients receiving long-term treatment with propranolol and metoprolol. Epinephrine was infused at graded rates of 0.5, 1.0, 2.0, and 4.0 micrograms/min. During propranolol treatment epinephrine induced a marked pressor effect at all rates. There was a considerable rise in systolic as well as in diastolic blood pressure and heart rate fell. During metoprolol treatment there was only a slight rise in blood pressure and heart rate rose. Forearm blood flow was decreased by epinephrine during propranolol. Calculated forearm vascular resistance showed opposite effects. We conclude that infusion of small doses of epinephrine results in a marked difference in reaction in propranolol- and metoprolol-treated patients and that this may have relevance in the choice of beta blocker to be used in the treatment of hypertension.

Adrenergic beta-Antagonists↗
PubMed1982

Effects of cold exposure on blood pressure, heart rate and forearm blood flow in normotensives during selective and non-selective beta-adrenoceptor blockade.

Haemodynamic effects of a cold pressor test (foot immersion for 6 min in water at 5 degrees C) without medication and after the non-selective beta-adrenoceptor blocker propranolol and the selective beta-adrenoceptor blocker metoprolol were studied in 17 volunteers. In the control study as well as in the study with the beta-adrenoceptor blockers cold exposure caused comparable changes, namely a blood pressure rise and a reduction of forearm blood flow. The increase in heart rate during cold exposure was clearly and equally reduced by both beta-adrenoceptor blockers. Plasma noradrenaline rose significantly by 47%, plasma adrenaline did not change. It is concluded, that as to this kind of stress, beta 1-selective-adrenoceptor blockade confers no important advantage over non-selective beta-adrenoceptor blockade.

Adolescent↗
PubMed1981

Haemodynamic effects of cigarette smoking during chronic selective and non-selective beta-adrenoceptor blockade in patients with hypertension.

1 Haemodynamic effects of cigarette smoking before and during chronic treatment with propranolol and metoprolol were studied in 16 patients with essential hypertension. 2 Smoking of cigarettes induced an increase in blood pressure of the same degree in all experimental sessions. Heart rate increased by 16 beats/min during smoking alone, but increased significantly less, when a beta-adrenoceptor blocker was used. Forearm blood flow decreased during smoking in both medication periods. 3 Plasma adrenaline rose significantly during smoking from 0.37 nmol/l to 0.77 nmol/l; plasma noradrenaline did not change. 4 It is concluded that the blood pressure changes induced by smoking are not essentially altered during chronic treatment with selective or non-selective beta-adrenoceptor blockade. Only the increase in heart rate is significantly less pronounced during treatment with both drugs.

Adolescent↗
PubMed1980

Infusion of diazoxide in severe hypertension during pregnancy.

Eight patients with severe pre-eclampsia or eclampsia were treated with diazoxide. The drug was administered on 3 occasions as a bolus injection (300 mg within 10 sec) and on 8 occasions as an infusion (15 mg/min, total amount 5 mg/kg body weight). The hypotensive effect at 30 and 60 min (stable hypotensive effect) and at 7 h (long-term effect) were the same with both modes of administration. The maximal decrease in blood pressure was reached in 5 min after bolus injection, compared to 25 min with the infusion. If diazoxide is used in severe pre-eclampsia and eclampsia, it should be administered preferably by the infusion method, because this results in a more gradual decline in blood pressure. Furthermore, the administration can easily be interrupted in cases of an exaggerated drop in blood pressure.

Adult↗
PubMed1980

Serum concentrations of immunoreactive calcitonin in patients with hypergastrinaemia.

In order to test tthe hypothesis that chronically elevated serum gastrin levels induce hypercalcitoninaemia, we have measured serum calcitonin levels in patients with chronic hypergastrinaemia. Basal serum calcitonin concentrations were found to be elevated in 2 of 23 patients with Zollinger-Ellison syndrome, but not in 16 patients with hypergastrinaemia due to achlorhydria or a single patient with primary hypergastrinaemia of antral origin. Both Zollinger-Ellison patients with hypercalcitoninaemia (0.31 and 0.79 ng/ml) had multiple endocrine adenomatosis type 1, but no medullary carcinoma of the thyroid. The hypercalcitoninaemia in these patients does not seem to be related to multiple endocrine adenomatosis type 1, since serum calcitonin was normal in 12 normogastrinaemic patients with hyperparathyroidism from families with multiple endocrine adenomatosis type 1. We conclude that chronically elevated serum gastrin levels do not result in hypercalcitoninaemia.

Calcitonin↗
PubMed1979

Influence of selective and non-selective beta-adrenoreceptor blockade on the haemodynamic effect of adrenaline during combined antihypertensive drug therapy.

1. Haemodynamic effects of adrenaline were studied in 27 hypertensive patients, succesively during treatment with propranol and metoprolol. In 12 patients beta-adrenoreceptor blockade was combined with diuretics and in 15 patients the blockade was combined with vasodilators. 2. During propranolol adrenaline caused a marked pressor effect: there was a considerable rise in systolic as well as in diastolic blood pressure and a marked fall in heart rate. During metoprolol there was only a slight rise in blood pressure and an increase in heart rate. 3. Forearm blood flow was decreased by adrenaline during propranolol and was increased during metoprolol. Calculated vascular resistance showed opposite changes. 4. Results were essentially the same when beta-adrenoreceptor blockade was combined with diuretics or with vasodilators and did not differ from previous results obtained in patients treated by blockade alone. 5. If adrenaline infusion can be considered as a model for acute stress, our results seem to favour a selective beta 1-adrenoreceptor blocking agent over a non-selective one, even when the blocker is combined with a diuretic or a vasodilator.

Adult↗