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Biomedical subjects

T Thien

Publications and source records attributed to T Thien.

At least 253 records · Page 14Linked to original sources
PubMed1986

Normal sympathetic neural activity in patients with mitral valve prolapse.

The hemodynamic and neurohumoral responses to head-up tilt and isometric exercise were studied in 14 mitral valve prolapse (MVP) patients with and 10 MVP patients without complaints and in 16 healthy control subjects. Plasma catecholamines at rest were not different between the three groups and neither were their changes during either test. The hemodynamic changes during head-up tilt were not different between the three groups. The symptomatic MVP patients showed a lower rise in diastolic blood pressure (14.3 +/- 6.4%) than the controls (22.9 +/- 9.6%) (p less than 0.05) during isometric exercise. In view of the fact that the neurohumoral responses to both tests were the same for all groups, we cannot support the suggestions from other studies that MVP patients have an impaired or enhanced sympathetic tone. Moreover, since there were no differences between symptomatic and asymptomatic MVP patients it is doubtful whether the complaints of symptomatic MVP patients are related to a high sympathetic neural activity.

Adult↗
PubMed1986

Influence of slow calcium-channel blockade on the cardiovascular effects of coffee.

An increase in blood pressure after coffee and caffeine has recently been reported. A possible pharmacological mechanism for this pressor response is a rise in the intracellular calcium concentration, caused by an increase in calcium influx due to a direct effect of caffeine. Accordingly, the cardiovascular effects of drinking coffee after placebo and verapamil 3 X 80 mg in 1 day in 10 normotensive volunteers have been examined in a single-blind study. After placebo, coffee led to an increase in blood pressure (7/14 mm Hg), and a fall in heart rate (-7 beats/min); forearm blood flow did not change. Plasma epinephrine rose (257%), plasma norepinephrine did not change and the plasma renin activity fell significantly. The haemodynamic and humoral changes after coffee were not altered by pretreatment with verapamil. It is concluded that increased transmembrane calcium influx after caffeine does not appear to be an important pharmacological mechanism for the circulatory effects of coffee.

Adult↗
PubMed1986

Double-blind, placebo-controlled study of prazosin in Raynaud's phenomenon.

We performed a randomized, double-blind, placebo-controlled, crossover study of the therapeutic efficacy of prazosin (1 mg t.i.d.) in 24 patients with Raynaud's phenomenon. Comparison of prazosin vs. placebo showed a moderate subjective improvement with a reduction of the daily number (P = 0.003) and duration (P = 0.02) of attacks. Patients showed a marked preference (P = 0.0002) for prazosin. Finger skin temperature and laser Doppler estimated finger skin blood flow, assessed during a standard finger cooling test, revealed a beneficial effect of prazosin (P = 0.0001 and P = 0.003, respectively). No differences in reaction to therapy could be found between patients with Raynaud's disease and secondary Raynaud's phenomenon. We conclude that prazosin is useful in the treatment of digital vasospastic disease, with an overall good response in two thirds of patients.

Adolescent↗
PubMed1986

The role of epinephrine in the circulatory effects of coffee.

The circulatory response to coffee was studied in 10 normotensive, 10 bilaterally adrenalectomized, and 10 hypertensive subjects. In the normotensive group, drinking coffee exerted a rise in blood pressure (+5.1/+11.5 mm Hg), a fall in heart rate (-6.0 bpm), a rise in plasma epinephrine (+257.2%), and no change in plasma norepinephrine. The response to coffee in the hypertensive group was similar or even enhanced. In the patients who had undergone adrenalectomy, the coffee-induced rise of diastolic blood pressure was attenuated (+7.9 mm Hg; P less than 0.05), whereas plasma norepinephrine showed a fall (-20.8%) and plasma epinephrine remained undetectable throughout all tests. Additionally, a fall of plasma renin activity after coffee was observed in all three groups. We conclude that the pressor response to coffee is not purely a result of circulating epinephrine or to stimulation of the renin-angiotensin-aldosterone system. On the other hand, the coffee-induced increase of plasma epinephrine may increase the pressor response to coffee.

Adrenalectomy↗
PubMed1986

The influence of intrinsic sympathomimetic activity and beta-1 receptor selectivity on the recovery of finger skin temperature after finger cooling in normotensive subjects.

A double-blind randomized study was designed to investigate differences in the recovery of finger skin temperature after finger cooling during dosing with placebo or one of four beta-blockers: propranolol, atenolol, pindolol, and acebutolol. In 11 normotensive nonsmoking subjects, finger skin temperature was measured with a thermocouple before and 20 minutes after immersion of one hand in a water bath at 16 degrees C. This finger cooling test caused no significant changes in systemic hemodynamics such as arterial blood pressure, heart rate, and forearm blood flow. The recovery of finger skin temperature during propranolol dosing was better than that during pindolol and atenolol dosing. There were no differences between the recoveries of skin temperature during pindolol, atenolol, and acebutolol dosing. Thus we could demonstrate no favorable effect of intrinsic sympathomimetic activity or beta 1-selectivity on the recovery of finger skin temperature after finger cooling.

Acebutolol↗
PubMed1986

The effects of sulindac and indomethacin on the anti-hypertensive and diuretic action of hydrochlorothiazide in patients with mild to moderate essential hypertension.

In this double-blind two period crossover study, we investigated the effect of indomethacin and sulindac on blood pressure in 25 hypertensive patients being treated with hydrochlorothiazide. The study consisted of seven 4 week periods. In the first and the last period the patients took placebos, in period two, four and six they were treated with hydrochlorothiazide 50 mg once daily alone, and in the third and fifth period hydrochlorothiazide 50 mg once daily was given in combination with either indomethacin 50 mg twice daily or sulindac 200 mg twice daily in double-blind random order. Blood pressure, measured by sphygmomanometer and arteriosonde, and body weight were determined every 2 weeks. Compared with placebo hydrochlorothiazide decreased the mean arterial pressure by 8%. Addition of both indomethacin and sulindac resulted in only slight and generally similar changes of this blood pressure lowering effect. This was found both for the whole group and when both treatment sequence groups were analysed separately. In contrast to sulindac, indomethacin attenuated the hydrochlorothiazide-induced decreases of body weight, plasma potassium and the increase of plasma renin activity. Both non-steroidal anti-inflammatory drugs (NSAID) reduced the 24 h urinary excretion of prostaglandins (PGs), i.e. PGF2 alpha, 6 ketoPGF1 alpha and thromboxane B2 except PGE2. From this study it can be concluded that, in contrast to sulindac, indomethacin attenuated the diuretic action of hydrochlorothiazide, however apparently without consequences for its long-term blood pressure lowering effect. This study does not support the hypothesis that the difference between the two NSAIDs can be explained by different effects on renal PG synthesis.

Adult↗
PubMed1985

Circulatory effects of coffee in relation to the pharmacokinetics of caffeine.

Drinking coffee results in an increase in blood pressure (BP) after an interval of caffeine abstinence. During chronic caffeine intake this pressor response disappears and adaptation to the circulatory effects of caffeine develops. This study was designed to determine whether a pressor response to coffee occurs during chronic caffeine intake if low basal plasma caffeine levels are achieved by a period of caffeine abstinence, defined by individual plasma caffeine half-life. In 8 normotensive subjects, circulatory measurements were studied after ingestion of coffee in 2 strengths, decaffeinated coffee and hot water after a caffeine abstinence of 4.5 times individual caffeine half-life. These measurements were compared to the same protocol without intervention. Coffee of both strengths resulted in a similar increase in BP (diastolic BP +/- 15%). The coffee-induced increase in forearm blood flow and plasma epinephrine levels were less pronounced. Decaffeinated coffee induced a smaller increase of diastolic BP, and after water, no changes were observed. Additionally, a negative correlation was found between the coffee-induced BP increase and basal plasma caffeine level in a group of 30 normotensive subjects (r = -0.71, p less than 0.001). During chronic caffeine intake, subjects with short plasma caffeine half-life are exposed to a pressor response after drinking coffee, despite the phenomenon of adaptation.

Adult↗
PubMed1985

The cardiovascular effects of regular and decaffeinated coffee.

In a single-blind study the effects of drinking two cups of regular or decaffeinated coffee on blood pressure, heart rate, forearm blood flow and plasma concentrations of caffeine, renin and catecholamines were studied in 12 normotensive subjects. Drinking regular coffee led to a rise of blood pressure, a fall of heart rate and an increase of plasma catecholamines. Decaffeinated coffee induced a smaller increase of diastolic blood pressure without changing other parameters. This study shows that the cardiovascular effects of drinking coffee are mainly the result of its caffeine content.

Adult↗
PubMed1985

The course of blood pressure after a meal: a difference between young and elderly subjects.

The effect of a standardized breakfast (405 kcal) on blood pressure and heart rate was studied in 25 healthy elderly subjects (mean age 79.8 +/- 5.7 years) and in 20 healthy young volunteers (mean age 31.5 +/- 4.8 years). In the elderly the maximal fall of systolic blood pressure was 7.1 +/- 1.5% and of diastolic blood pressure 14.1 +/- 1.7% at 50 min after the start of the breakfast. In the younger group, blood pressure did not change significantly after breakfast. In both groups heart rate increased significantly. The postprandial blood pressure reduction in the elderly was correlated with preprandial blood pressure. There was also a significant correlation between blood pressure reduction and age if corrected for preprandial blood pressure. In conclusion, in contrast to the younger subjects, elderly healthy subjects showed a clear blood pressure reduction after breakfast.

Adult↗
PubMed1984

Influence of non-steroidal anti-inflammatory drugs on diuretic treatment of mild to moderate essential hypertension.

In an open triple crossover study in 10 patients with mild to moderate essential hypertension the influence was investigated of adding indomethacin 50 mg, naproxen 250 mg, or sulindac 200 mg, each twice daily for four weeks, to diuretic treatment with hydrochlorothiazide 50 mg a day. After two weeks' treatment with indomethacin a slight increase in blood pressure was observed, whereas both sulindac and naproxen tended to enhance the antihypertensive effect of hydrochlorothiazide. After treatment for four weeks, however, the effects of all three drugs on blood pressure appeared to be blunted. Furthermore, body weight increased significantly during treatment with indomethacin but not during treatment with naproxen or sulindac. No significant changes were found for various biochemical variables, including concentrations of plasma electrolytes and serum creatinine and albumin, plasma renin activity, plasma aldosterone concentration, and 24 hour urinary excretion of sodium and potassium, with the exception, however, of an increase in plasma potassium concentration during treatment with indomethacin. These observations suggest that the interaction of indomethacin, naproxen, and sulindac with diuretic treatment in mild to moderate essential hypertension is transient and of minor clinical importance.

Adult↗
PubMed1984

Exocrine pancreatic insufficiency and idiopathic haemochromatosis.

The case history of a 34-year-old patient with precirrhotic idiopathic haemochromatosis and severe chronic steatorrhoea is presented. The pancreas had a normal appearance on ultrasonography and endoscopic retrograde pancreaticography. However, pancreatic function tests revealed significant abnormalities. The pancreatic output of trypsin, amylase, lipase and bicarbonate was deficient and basal and stimulated serum pancreatic polypeptide levels were subnormal. In contrast, the oral glucose tolerance test was unimpaired. The pancreatic insufficiency had started suddenly during a summer vacation and may have had a viral aetiology. The hypothesis is advanced that in haemochromatosis the iron-laden pancreatic acinar and PP-producing cells are more susceptible to damage by viruses than normal pancreatic cells.

Adult↗
PubMed1983

Hemodynamic and humoral effects of coffee after beta 1-selective and nonselective beta-blockade.

Several studies report a substantial rise in plasma catecholamines after caffeine. Epinephrine infusion induces a pressor response after nonselective beta-blockade. We studied the hemodynamic and humoral effects of drinking coffee after placebo and after both nonselective (propranolol) and beta 1-selective (metoprolol) blockade in 12 normotensive subjects. After placebo, coffee induced a rise in systolic and diastolic blood pressure and a fall in heart rate, whereas forearm blood flow did not change. Plasma catecholamines, especially epinephrine (+150%), rose and plasma renin activity, fell after drinking coffee. The effects of coffee on blood pressure, forearm blood flow, and all humoral parameters were not altered by pretreatment with propranolol or metoprolol. The fall in heart rate after coffee, however, seemed to be greater during propranolol. We conclude that the rise in plasma epinephrine after coffee was too small to reveal differences in reaction in propranolol- and metoprolol-pretreated subjects.

Adolescent↗