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Biomedical subjects

A Amery

Publications and source records attributed to A Amery.

At least 127 records · Page 7Linked to original sources
PubMed1990

[Converting-enzyme inhibitors in the treatment of elderly hypertension patients].

According to this review of available data on converting enzyme inhibitors in elderly hypertensives, the drugs' hypotensive action has been clearly established and seems to be similar in degree to that of diuretics. Adverse reactions during converting enzyme inhibitor treatment in the elderly may be slightly more frequent than in younger patients, but whether this is related to the drugs themselves or to the general characteristics of elderly hypertensives has not been established. Likewise, whether or not the hypotensive action of converting enzyme inhibitors is age-related is as yet unknown. Finally, studies on the impact of converting enzyme inhibitors on morbidity, mortality and general well being in elderly patients have not been carried out or published. Thus, while the drugs appear to have usefulness in the older hypertensive, their benefits and precise use in this age group are not as yet definitive.

Aged↗
PubMed1990

Erythrocyte concentrations and transmembrane fluxes of sodium and potassium in essential hypertension: role of intrinsic and environmental factors.

The intraerythrocyte sodium concentration is increased in the erythrocytes of Zaïrean Bantu with untreated hypertension, while the red blood cell potassium is not different from that of normotensive subjects. Compared with whites, normotensive healthy blacks have a higher intracellular concentration of sodium due to a depressed activity of the sodium-potassium pump. Normotensive healthy males with a positive familial background of hypertension display higher erythrocyte sodium and lower cotransport activity. None of the two measurements offer a clear-cut genetic marker of essential hypertension. In healthy women, the erythrocyte sodium concentration is lowered during the luteal as compared with the follicular phase of the menstrual cycle. This variability explains the difference observed between men and women. A low-sodium diet stimulates the activity of the sodium-potassium ATPase pump, which leads to a decrease in the erythrocyte sodium concentration. Both alterations reverse only slowly during sodium repletion. It is therefore suggested that an adequate matching for race, sex, stage of the menstrual cycle (in women), family history of hypertension, and the amount of sodium in the diet should be a prerequisite for valid conclusions when interpreting the erythrocyte concentration and fluxes of sodium.

Biological Transport, Active↗
PubMed1990

Inheritance of heart structure and physical exercise capacity: a study of left ventricular structure and exercise capacity in 7-year-old twins.

The maximal aerobic power of endurance athletes is high and their heart is characterized by a larger left ventricular internal dimension than in non-athletes, and a proportional increase of wall thickness; these traits may be inherited and/or the consequence of intense physical training. To assess the influence of inheritance on physical exercise capacity and on echocardiographically determined cardiac structure, and to limit the effect of environmental factors as much as possible, we studied 15 monozygotic and 19 dizygotic 6- to 8-year-old twin pairs. Exercise capacity was expressed as the times at which the heart rates of, respectively, 150 and 170 beats min-1 were reached during a progressive exercise test on the treadmill. For these exercise times the within-pair variance was significantly larger in dizygotic compared with monozygotic twins. Therefore significant genetic variance was inferred, both when the exercise times were expressed as absolute values and after adjustment for body weight and gender. As for cardiac structure at rest, the results did not suggest a significant influence of genetic endowment on left ventricular internal diameter or on wall thickness; genetic variance was significant, however, for calculated left ventricular mass (P less than 0.05) and left ventricular mass adjusted for body weight and gender. The results are compatible with the notion that the high aerobic power of endurance athletes is at least partly inherited. Left ventricular internal dimension and wall thickness, which distinguish an athlete's heart at rest from the heart of a non-athlete, do not show a significant genetic component, suggesting that the qualities characteristic of an athlete's heart, at least as assessed at rest, are not inherited. The inheritance of aerobic power may be due to inheritance of non-cardiac factors or to cardiac features which are only expressed during exercise.

Blood Pressure↗
PubMed1990

Treatment of the elderly hypertensive patient.

It is generally accepted that increased blood pressure, especially high systolic blood pressure, is a major risk indicator in people over 60 years of age. Retrospective analyses of published trials show that when the elevation in arterial pressure has been firmly established by repeated blood pressure measurements, antihypertensive treatment should be considered for the following subgroups. (1) All elderly hypertensive patients with grade III or IV retinopathy, congestive heart failure or cerebral infarction or hemorrhage should be treated regardless of age or degree of blood pressure elevation. (2) In elderly patients with established mild hypertension and no symptoms or complications, non-pharmacological treatment should be started in patients less than 80 years of age, with antihypertensive drugs prescribed if diastolic pressure reaches 100 mmHg or more over 3 months or 95 mmHg or more over 6 months of follow-up. The therapeutic benefit of pharmacologic antihypertensive treatment has not yet been established in hypertensive patients over 80 years of age or in those with isolated systolic hypertension. All things considered, the indication to intervene pharmacologically should be viewed as becoming gradually more compelling as blood pressure rises. The more closely a patient's characteristics match those of a subset of elderly hypertensive patients in whom therapeutic benefit has been proven, the greater the need for pharmacologic treatment.

Aged↗
PubMed1990

Is a high serum cholesterol level associated with longer survival in elderly hypertensives?

The relationship between serum total cholesterol, measured at randomization, and mortality was investigated in 822 patients, who were followed for an average of 3.1 years in a double-blind trial, conducted by the European Working Party on High Blood Pressure in the Elderly. Serum cholesterol, measured at randomization, was 0.54 mmol/l higher in women than in men, and declined with increasing age in both men (0.028 mmol/l per year) and women (0.036 mmol/l per year). During follow-up on randomized treatment, cholesterol fell by a similar amount with placebo (0.11 mmol/l per year) and with active treatment (0.14 mmol/l per year). Active treatment consisted of hydrochlorothiazide (25-50 mg/day) plus triamterene (50-100 mg/day) with the addition of alpha-methyldopa (0.5-2.0 g/day) in one-third of the patients. Serum total cholesterol, measured at randomization, was independently and inversely correlated with total (P = 0.03), non-cardiovascular (P = 0.03) and cancer (P = 0.04) mortality during follow-up on double-blind treatment. Total and non-cardiovascular mortality were also negatively correlated with haemoglobin and body weight at randomization.

Aged↗
PubMed1990

Age-related effects of placebo and active treatment in patients beyond the age of 60 years: the need for a proper control group.

The age-related response to placebo and active antihypertensive treatment was evaluated in 742 elderly hypertensive patients who were followed in the double-blind placebo-controlled trial conducted by the European Working Party on High blood pressure in the Elderly (EWPHE). In the two treatment groups, the fall in systolic and diastolic blood pressures after 3 months was negatively correlated with age (P less than 0.02), indicating that the hypotensive effect of placebo and active treatment was more pronounced in older patients. Further comparison of the two treatment groups failed to demonstrate any statistical differences in the slopes of the hypotensive effect on age. These conclusions were not altered by cumulative adjustments for baseline blood pressure, pulse rate, serum creatinine and the presence of cardiovascular complications at entry. In conclusion, in the present study, a similar blood-pressure-lowering action which increased with age was observed on active and placebo treatment; thus, proof that an observed age-related hypotensive effect is caused by a particular drug requires comparison with a control group on placebo.

Aged↗
PubMed1990

Influence of opioid antagonism on plasma catecholamines in pheochromocytoma patients.

The present study investigated whether in vivo endogenous opioids inhibit the secretory activity of pheochromocytomas and whether opioid antagonists may be useful in the diagnosis of pheochromocytoma. In six patients with pheochromocytoma in whom the diagnosis was histologically confirmed after surgery, mean intraarterial blood pressure (BP) increased by 45 mm Hg within 3 min after intravenous (i.v.) injection of 2 mg glucagon (95% confidence interval 23-68 mm Hg); heart rate (HR) remained unchanged, whereas plasma norepinephrine (NE) increased by 216% (31-658%) and plasma epinephrine (EPI) increased by 203% (37-571%). Although glucagon stimulation confirmed the secretory potential of the pheochromocytomas, opioid antagonism by a 10-mg i.v. bolus of naloxone produced no significant change in plasma NE and EPI concentrations or intraarterial pressure. The present study does not support the hypothesis that release of catecholamines from pheochromocytomas is inhibited by endogenous opioids. Use of opioid antagonists as a tool in the diagnosis of pheochromocytoma therefore cannot be recommended.

Adrenal Gland Neoplasms↗
PubMed1990

Health effects of environmental exposure to cadmium: objectives, design and organization of the Cadmibel Study: a cross-sectional morbidity study carried out in Belgium from 1985 to 1989.

Cadmium is a cumulative environmental pollutant. For the general population mainly exposed by the oral route and through tobacco smoke inhalation, the kidney is the critical organ. Belgium is the principal producer of cadmium in Europe, and certain areas of the country are polluted by cadmium mainly because of past emissions from nonferrous industries. Preliminary studies carried out in one polluted area have suggested that environmental pollution might lead to an increased uptake of cadmium by the human body and possibly to health effects. Thus, a large-scale morbidity study has been initiated to assess the validity of this hypothesis. The present paper describes the protocol of this study. Its main objectives are to determine to what extent environmental exposure to cadmium resulting from industrial emissions may lead to accumulation of the metal in the human organism; to establish whether or not environmental exposure may induce renal changes and/or influence blood pressure; and to assess the acceptable internal dose of cadmium for the general population. The study design takes advantage of the fact that biological indicators of exposure, body burden, and early nephrotoxic effects of cadmium are available, which increase the likelihood of detecting a cause-effect relationship.

Adult↗
PubMed1990

Reference values for ambulatory blood pressure: a meta-analysis.

The aim of the present study was to perform a meta-analysis of published studies in an attempt to determine the mean and range of normal ambulatory blood pressure. Twenty-two studies, including a total of 2638 subjects, were reviewed. Most studies were compatible with a mean 24-h ambulatory pressure in the range of 115/70-120/75 mmHg, a mean daytime pressure of 120/75-125/80 mmHg and a mean night-time pressure of 105/60-110/65 mmHg. With weighting for the number of subjects included in the individual studies, the 24-h ambulatory pressure averaged 117/72 mmHg, the daytime pressure 122/77 mmHg and the night-time pressure 106/64 mmHg. The night:day pressure ratio averaged 0.87 for systolic and 0.83 for diastolic pressure, ranging from 0.79 to 0.92 and from 0.75 to 0.90, respectively, across the individual studies. With the mean +/- 2 standard deviation intervals in the various studies taken as normal, the range of normality averaged 97/57-137/87 mmHg over 24 h, 101/62-143/91 mmHg for the daytime pressure and 86/48-127/79 mmHg for the night-time pressure. Until the results of prospective studies on the relationship between ambulatory blood pressure and the incidence of cardiovascular morbidity and mortality become available, these estimates of normal ambulatory pressure could be applied as reference values in clinical practice.

Adolescent↗
PubMed1990

Antihypertensive effect of doxazosin and atenolol in short- and long-term double-blind comparison.

The antihypertensive effect and safety of doxazosin once daily as well as the effect on serum lipids was compared with that of atenolol once daily in 40 patients with mild to moderate hypertension. During the first 4 weeks, all patients received placebo therapy. During the subsequent 46 weeks, patients were randomized to doxazosin or atenolol treatment. Treatment was initiated with 1 mg doxazosin or 50 mg atenolol once daily. The dose could be doubled biweekly for 10 weeks until a final dose of 16 mg doxazosin or 100 mg atenolol was reached. The patients then entered the maintenance phase for 36 weeks. The average final dose of doxazosin was 9.2 +/- 1.3 (SEM) mg and that of atenolol was 76.5 +/- 6.2 mg. During the 46 weeks of active treatment, the recumbent diastolic blood pressure (DBP) tended to be lower (p less than 0.05) in patients receiving atenolol at 10, 12, and 22 weeks of treatment. Recumbent systolic BP (SBP) and standing SBP and DBP were not different, however, between patients receiving doxazosin and those receiving atenolol. Recumbent and standing heart rate (HR) were lower (p less than 0.01) during atenolol. The decrease in serum total triglycerides, total cholesterol, and low-density lipoprotein (LDL)-cholesterol after 46 weeks of doxazosin was different (p less than 0.05) from the changes observed during atenolol therapy. Our data indicate that the antihypertensive action of doxazosin is accompanied by favorable effects on serum lipids.

Adult↗
PubMed1990

Intervention trials in elderly hypertensive patients: a review.

Results from total and cause-specific mortality from various randomly allocated intervention trials of antihypertensive drug treatment in elderly hypertensives have been reviewed, compared and pooled. Mortality from all causes tended to decrease in all trials, but this decrease was not statistically significant in any of the trials separately, nor when all results were pooled. When the results of all the trials were combined, there was a significant overall decrease in cardiovascular mortality of 28%. This decrease was mainly related to a significant reduction in cerebrovascular mortality of 41%. Mortality from ischaemic heart disease also tended to decrease by 28%, but statistical significance was not reached.

Age Factors↗
PubMed1990

Effects of nitrendipine and atenolol on blood pressure and intracellular sodium in hypertensive blacks.

Thirty-five hypertensive black patients were randomized in a double-blind fashion to receive either atenolol 100 mg per day (n = 17) or nitrendipine 20 mg daily (n = 18) for six weeks. Atenolol and nitrendipine significantly reduced blood pressure (P less than 0.05 or less). However, the magnitude of the decrease in supine systolic blood pressure (SBP) and diastolic blood pressure (DBP), and in standing diastolic pressure was more pronounced (P less than 0.05 or less) in the nitrendipine than in the atenolol group. Neither of the drugs significantly affected the erythrocyte sodium and potassium concentrations or the ouabain-sensitive efflux of sodium. In multiple regression analysis the changes in supine SBP and DBP with nitrendipine were independently and negatively correlated with the patients' age and initial blood pressure, and positively with the change in supine pulse rate; the change in supine SBP was also negatively correlated with initial erythrocyte sodium concentration. Our results suggest that nitrendipine is more efficient than atenolol in hypertensive blacks and that besides older age and higher pre-treatment. BP levels, a higher intracellular sodium concentration could predict a greater response to nitrendipine.

Atenolol↗
PubMed1990

Evidence for a curvilinear relation between blood pressure and urinary sodium in men.

With the use of a linear model, the relation between urinary sodium and blood pressure has been reported to be positive, non-significant, or negative. The hypothesis that this relationship is more complex than linear was investigated in two different study populations, which were independently recruited and examined by different observers. In 1,071 men randomly selected from the general population and in an unrelated sample of 1,209 military men, systolic and diastolic blood pressure were correlated with urinary sodium following a model, which included both the linear and quadratic terms of urinary sodium. In both groups of men, these second order models, adjusted for age and body mass index, provided a better fit (P less than 0.05) than the relationships with only the linear term of urinary sodium. The quadratic models explained from 0.35 to 1.10% of the blood pressure variance. Third order models, which in addition included the cubic term of urinary sodium, did not further improve the correlations between systolic and diastolic blood pressure and urinary sodium in men. In 1,010 women drawn from the general population and in 499 military women, neither the first nor the second order correlations between systolic and diastolic blood pressure and urinary sodium were statistically significant. In conclusion, the present results, reproducible in two different study populations, suggest that a second order model is more appropriate than a simple linear correlation to describe the weak relationship between blood pressure and urinary sodium in men. However, recommendations for the prevention of hypertension must not be changed, until the present findings are confirmed by intervention studies.

Adolescent↗
PubMed1990

Inhibition of human erythrocyte and leukocyte Na+, K(+)-pump activity by lysophosphatidylcholines.

Synthetic lysophosphatidylcholines (LPCs) were examined for their effects on erythrocyte and leukocyte Na+,K(+)-pump activity, on erythrocyte Na+,K(+)-cotransport activity and on the passive permeability of the red blood cell membrane. Erythrocyte and leukocyte Na+,K(+)-pump activity was estimated by ouabain-sensitive 86Rb-uptake and erythrocyte Na+,K(+)-cotransport activity by bumetanide-sensitive 86Rb-uptake. Bumetanide, ouabain-resistant 86Rb-uptake was considered as a measure of the passive permeability of the red blood cell membrane. LPCs containing long chain fatty acids such as myristoyl, palmitoyl, lauroyl, stearoyl and oleoyl inhibited erythrocyte and leukocyte Na+,K(+)-pump activity and erythrocyte Na+,K(+)-cotransport activity, while they stimulated the passive membrane permeability of the red blood cells. LPCs containing lauroyl, the shortest fatty acid in this group, had the lowest inhibitory activity, while LPCs with intermediate chain length fatty acids such as caproyl and decanoyl had no effect. The order of inhibitory action of these LPCs on erythrocyte and leukocyte Na+,K(+)-pump activity was: palmitoyl greater than stearoyl greater than myristoyl greater than oleoyl greater than lauroyl.

Adult↗
PubMed1989

Urapidil-induced hemodynamic changes in humans.

In hypertensive patients as well as in normal subjects urapidil has a hypotensive action. This is mainly mediated by a peripheral alpha 1-adrenoceptor blockade with a decrease in systemic vascular resistance; in addition, during acute animal experiments a centrally mediated hypotensive action was demonstrated, possibly by 5-hydroxytryptamine1A (5-HT1A)-receptor stimulation. Studies in humans showed an increase in cardiac output, which was not always significant; it did result either from an increased heart rate or an increased stroke volume. Acute changes in pulmonary hemodynamics after administration of urapidil were most pronounced in patients with pulmonary hypertension: pulmonary artery pressure and pulmonary vascular resistance decreased significantly and pulmonary capillary wedge pressure decreased nonsignificantly. A small reduction in pulmonary artery pressure and capillary wedge pressure were seen in patients with congestive heart failure and in patients in whom acute blood pressure elevation developed after coronary bypass surgery. In patients with essential hypertension forearm, renal and splanchnic flow were shown to increase and vascular resistance to decrease significantly after acute intravenous doses of urapidil. The hemodynamic changes during chronic therapy are largely unknown, except for systemic vascular resistance which remains decreased.

Acute Disease↗