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Biomedical subjects

A Amery

Publications and source records attributed to A Amery.

At least 109 records · Page 6Linked to original sources
PubMed1991

The effect of antihypertensive treatment on electrocardiogram voltages in the EWPHE trial.

Long-term effects of antihypertensive treatment on various electrocardiogram (ECG) voltages and the association between ECG findings at randomization and subsequent mortality were evaluated in the double-blind, placebo-controlled trial of elderly hypertensive patients, conducted by the European Working Party on High Blood Pressure in the Elderly (EWPHE). Patients were treated with a combination of hydrochlorothiazide and triamterene or matching placebo; methyldopa or placebo was added if blood pressures remained high. RaVL and SV1 + RV5 at randomization were related to systolic blood pressure (SBP) and RaVL was also related to diastolic blood pressure (DBP), after adjustment for age, gender, and body mass index (BMI). When adjusted for age and body mass index, the decreases in RaVL and SV1 + RV5 were not correlated with the changes in SBP after 1 year of active treatment but the decreases in SV1 + RV5 were positively related to the fall in DBP. After 4 years of active treatment, the fall in SBP was associated with decreases in RaVL and in SV1 + RV5, after adjustment for age and changes in BMI.

Aged↗
PubMed1991

Effects of exposure to cadmium on calcium metabolism: a population study.

The objective was to investigate the hypothesis that environmental exposure to cadmium may affect calcium metabolism in the population at large. The 1987 participants (965 men and 1022 women), from 20 to 80 years old, constituted a random sample of the population of four Belgian districts. The urinary excretion of cadmium, a measure of lifetime exposure, averaged 9.3 nmol/24 h in men (range 0.4-324 nmol/24 h) and 7.1 nmol/24 h (range 0.1-71 nmol/24 h) in women. Serum alkaline phosphatase activity and the urinary excretion of calcium correlated significantly and positively with urinary cadmium excretion in both men and women, and serum total calcium concentration negatively with urinary cadmium excretion in men only. The regression coefficients obtained after adjustment for significant covariates indicated that when urinary cadmium excretion increased twofold, serum alkaline phosphatase activity and urinary calcium excretion rose by 3-4% and 0.25 mmol/24 h respectively, whereas in men serum total calcium concentration fell by 6 mumol/l. After adjustment for significant covariates the relation between serum total calcium concentration and urinary cadmium excretion was not significant in women. The findings suggest that even at environmental exposure levels calcium metabolism is gradually affected, as cadmium accumulates in the body. The morbidity associated with this phenomenon in industrialised countries remains presently unknown and requires further investigation.

Adult↗
PubMed1991

Effect of cadmium on transmembrane Na+ and K+ transport systems in human erythrocytes.

The effects of cadmium (Cd2+) on Na+,K(+)-ATPase in disrupted human erythrocyte membranes and on various transmembrane Na+ and K+ transport systems in intact erythrocyte suspensions were studied. Cadmium2+ inhibited the erythrocyte Na+,K(+)-ATPase enzyme with a 50% inhibition at a Cd2+ concentration of 6.25 microM. The Cd2+ inhibition in the human erythrocyte was non-competitive with respect to Na+,K+, and ATP. Cadmium2+ exerted no acute effect, however, on the Na+,K(+)-ATPase pump activity as measured by the ouabain sensitive 86Rb uptake or Na+ efflux in intact red blood cells. Cadmium2+ also inhibited the Ca2+ dependent K+ channels in human red blood cells, whereas it had no effect on Na+,K+ cotransport, Na+,Li+ countertransport, anion carrier, and the number of active Na+ pump units. The data indicate that in human erythrocytes under acute conditions Cd2+ exerts an inhibitory effect on Na+,K(+)-ATPase enzyme in disrupted erythrocytes and the Ca2+ stimulated K+ efflux in intact red blood cells without affecting the Na+ pump, Na+,K+ cotransport, and Na+,Li+ countertransport activity.

Biological Transport, Active↗
PubMed1991

Effect of prostaglandin inhibition by indomethacin on plasma active and inactive renin concentration in men.

The effect of inhibition of prostaglandin synthesis by indomethacin on active renin and on acid-activable inactive renin was studied in nine healthy, sodium-replete men, both at rest and exercise. These volunteers were investigated after pretreatment with placebo or indomethacin, 150 mg daily for 3 days. Indomethacin induced a decrease in active (p = 0.004), total (p less than 0.001), and inactive (p = 0.02) renin at rest recumbent on average by 42, 19, and 8%, respectively, and at rest sitting on average by 45, 15, and 3%, respectively. Inhibition of prostaglandins with indomethacin reduced (p less than 0.001) active and total renin at each level of work load but not (p = 0.32) inactive renin. However, the exercise-induced stimulation (p less than 0.05) of active and total renin still occur during indomethacin. Indomethacin reduced (p less than 0.001) at rest sitting and at maximal exercise the plasma concentrations of immunoreactive prostaglandins E2 by 50 and 54%, respectively, prostaglandin F2 alpha by 36 and 39%, respectively, and 13,14-dihydro-15-keto-prostaglandin F alpha by 38 and 60%, respectively. The urinary excretion of immunoreactive prostaglandin E2 and F2 alpha was also reduced.

Adult↗
PubMed1991

Heritability of aerobic power and anaerobic energy generation during exercise.

Twenty-nine pairs of monozygotic twins and 19 pairs of dizygotic twins, all male, ages 18-31 yr, performed a graded uninterrupted exercise test on the bicycle ergometer to exhaustion. By use of path analysis, the genetic variance of measured peak O2 uptake was estimated at 77% (P less than 0.001), at 71% (P less than 0.001) after adjustment for weight and skinfold thickness, and at 66% (P less than 0.001) after additional adjustment for weekly hours of sports participation. O2 uptake at a heart rate of 150 beats/min, a submaximal estimate of exercise capacity, showed less genetic variance, i.e., 61% (P less than 0.001) before and 50% (P less than 0.001) after weight adjustment and only 16% (NS) after correction for life-style factors. Similarly, the heritability of peak O2 uptake, when estimated from submaximal data, was 68% (P less than 0.001), 40% (P = 0.05), and 26% (NS), respectively. Mechanical efficiency had no significant genetic component. O2 uptake at the respiratory exchange ratio of 0.95 and the slope of the curvilinear relationship between CO2 output and O2 uptake, used to assess the anaerobic energy generation during progressive exercise, showed significant (P less than 0.001) genetic variance before (72 and 74%) and after adjustment for weight (67 and 69%) and sports participation (63 and 57%). The heritability of peak aerobic power remained significant (58%; P less than 0.001) after adjustment for these expressions of anaerobic energy generation. In conclusion, the genetic variance of measured peak O2 uptake is significant and persists after adjustment for anthropometric characteristics, life-style factors, anaerobic energy generation, and mechanical efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Prognostic significance of exercise versus resting blood pressure in hypertensive men.

The outcome of 143 male hypertensive patients, investigated in the period 1972-1982, was ascertained in 1989 to determine if brachial artery pressure measured during a progressive graded exercise test on the bicycle ergometer is a better predictor of mortality and cardiovascular events than pressure at rest. During the total follow-up time of 1,573 patient years, 27 patients suffered at least one fatal or nonfatal cardiovascular event and 13 patients died. Using the Cox regression model, the age-adjusted relative hazard rates of systolic pressure at supine rest, at 50 W, at peak work load, and at 50% of peak exercise capacity were significant for total mortality (p less than or equal to 0.01) and for cardiovascular events (p less than or equal to 0.03). Pressure during exercise, however, did not significantly (p = 0.11-0.97) predict the outcome of the patients when age and pressure at rest were taken into account. The results were similar for diastolic pressure. In conclusion, intra-arterial pressures at rest and during submaximal and peak exercise significantly predict mortality and the incidence of cardiovascular events in hypertensive men, independent of age. However, there is no additional prognostic precision of the exercise pressures when age and the rest pressure are taken into account.

Adolescent↗
PubMed1991

Treatment of isolated systolic hypertension in the elderly.

Isolated systolic hypertension affects between 10 and 20% of the elderly population and carries a substantial risk of cardiovascular complications. As no prospective, randomized trials have produced scientific evidence of a treatment benefit in elderly patients with isolated systolic hypertension, opinion on when and how to treat this condition differs among expert committees as well as among individual doctors. This article reviews the present treatment policies in patients with isolated systolic hypertension. It describes the ongoing intervention studies that have been designed to examine the hypothesis that antihypertensive treatment confers a benefit to elderly patients with isolated systolic hypertension in terms of a reduced morbidity and mortality. The Syst-Eur trial, which was recently initiated by the European Working Party on High Blood Pressure in the Elderly, is described in greater detail.

Aged↗
PubMed1991

Reference values for the ambulatory blood pressure and the blood pressure measured at home: a population study.

In order to determine reference values for the ambulatory blood pressure, a population sample of 328 subjects, aged 20-81 years, who reported themselves to be in good health, was investigated. The ambulatory blood pressure was recorded over 24 h, taking measurements at 20 min intervals from 8 am to 10 pm, and at 45 min intervals from 10 pm to 8 am. Blood pressure was also measured by trained observers on each of two separate home visits (5 readings per visit). The ambulatory blood pressure in the 328 subjects averaged 118/71 mmHg over 24 h, 124/76 mmHg during the day (10 am-8 pm), and 108/62 mmHg at night (0 am-6 am). Blood pressure measured by an observer at the occasion of the second home visit was 4/5 mmHg lower (P less than 0.001) than the daytime ambulatory blood pressure. The 95th centiles for the daytime ambulatory pressures were 144/95 mmHg in 85 men below age 50; 154/90 mmHg in 74 men aged greater than or equal to 50 years; 132/85 mmHg in 96 women below age 50; and 151/91 mmHg in 73 women aged greater than or equal to 50 years. The 95th centiles for the nighttime pressures in these four sex-age groups were 124/79, 140/83, 121/70, and 132/72 mmHg, respectively.

Adult↗
PubMed1991

Isolated systolic hypertension in the elderly: implications of Systolic Hypertension in the Elderly Program (SHEP) for clinical practice and for the ongoing trials.

The Systolic Hypertension in the Elderly Program (SHEP) was a double-blind placebo-controlled outcome trial on the treatment of isolated systolic hypertension (systolic pressure: 160-219 mmHg and diastolic pressure less than 90 mmHg). From 447, 921 screenes (age greater than or equal to 60 years) 4,736 patients were randomised. A significant reduction of non-fatal stroke (37%), non-fatal myocardial infarction (33%) and left ventricular failure (54%) was observed in the active treatment group. By contrast, the reduction in transient ischaemic attacks (25%), and in total (13%), cardiovascular (20%), cerebrovascular (29%) and coronary (20%) mortality did not reach a level of statistical significance. SHEP is a landmark trial on the treatment of isolated systolic hypertension (ISH) in the elderly. However, the question to what extent the SHEP results can be extrapolated to clinical practice remains open for debate. Indeed, it is possible that due to selection, the SHEP patients were not entirely representative of the elderly with ISH in the population at large. By contrast with previous intervention studies in elderly patients with combined systolic and diastolic hypertension, the SHEP trail did not demonstrate a significant beneficial effect of antihypertensive treatment on any of the cardiovascular mortality endpoints. Confirmation or rejection of the SHEP results in other trials, including the Syst-Eur study, conducted by the rejection of the SHEP results in other trials, including the Syst-Eur study, conducted by the European Working Party on High Blood Pressure in the Elderly and the Chinese trial in elderly ISH patients, is now awaited.

Aged↗
PubMed1991

Methods for describing the diurnal blood pressure curve.

Ambulatory blood pressure recordings supply information on the blood pressure variation during habitual daily activities and sleep. Whether the circadian blood pressure curve is modulated by an endogenous clock or whether the diurnal fluctuations in blood pressure are mainly or exclusively determined by the pattern of activity remains disputed. Whatever the underlying mechanism, most experts agree that it still remains to be ascertained whether the blood pressure profile can help in unraveling the pathophysiology of hypertension and determining a subject's cardiovascular risk. The methods for parametrizing the diurnal blood pressure curve in individual subjects, summarized in this article, may provide summary statistics for larger groups of individuals or for the population at large.

Activities of Daily Living↗
PubMed1991

An inventory of studies on ambulatory blood pressure in large groups of subjects.

We made an inventory of 19 studies that have been or are being undertaken to better characterize the distribution of ambulatory blood pressure in the population at large or in larger groups of individuals selected from the population. No study was without some degree of selection in the recruitment of its subjects, but none of the subjects was selected or excluded on the basis of ambulatory blood pressure. These studies could provide the data required to define more precise, age- and sex-specific, diagnostic criteria for ambulatory blood pressure measurement in day-to-day clinical practice.

Blood Pressure↗
PubMed1991

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

Inhibitors of the angiotensin conversion enzyme are used more and more for the treatment of hypertension patients. In this literature-review the efficiency of these drugs in lowering the blood pressure of aged patients is examined, as well as their relation to age and their influence on the morbidity and mortality of older people.

Aged↗
PubMed1991

Ambulatory blood pressure monitoring in clinical trials.

Monitoring ambulatory blood pressure, instead of taking pressure readings in hospital, avoids the so-called white-coat effect and allows more readings to be obtained over a longer period of time. It improves the accuracy of the blood pressure estimate and increases the statistical power of therapeutic trials for hypertension. Subjects with white-coat or office hypertension can be detected by ambulatory blood pressure monitoring and excluded from clinical trials. In 23 studies, including a total of 3304 normotensive subjects, the 24-h ambulatory blood pressure averaged 118/72 mmHg; the daytime and night-time pressures were 123/76 mmHg and 106/64 mmHg, respectively. If the mean plus two standard deviation (s.d.) interval is considered the upper limit of normal, the meta-analysis suggested that hypertension may be suspected if the 24-h pressure exceeds 129/87 mmHg, or if the daytime or night-time pressures are higher than 146/91 mmHg or 127/79 mmHg, respectively. On balance, most studies suggest that placebo effects on blood pressure are not observed when blood pressure is measured with ambulatory recorders. If confirmed, this observation indicates that it is possible to simplify the design of trials in the field of hypertension. Ambulatory blood pressure readings should be obtained with properly validated monitors. If the recordings are of sufficient quality, editing does not increase the precision of the subsequent statistical analyses. The statistical analyses should account for diurnal rhythms, and subject and treatment effects.

Antihypertensive Agents↗
PubMed1991

Exercise blood pressure and target organ damage in essential hypertension.

To study whether exercise blood pressure is more closely related to the complications of hypertension than resting blood pressure, 169 patients with essential hypertension, aged 16-66 years, (WHO stages I and II), underwent a graded uninterrupted exercise test on the bicycle ergometer up to exhaustion. BP was measured in intra-arterially. Target organ damage was assessed by eye-fundus grade and by electrocardiographic voltage criteria and T-wave patterns. After adjustment for relevant covariates (age, gender, body height and weight), the manifestations of target organ damage were significantly related to systolic (r ranging from 0.19 to 0.39) and diastolic (r ranging from 0.11 to 0.30) intra-arterial pressure at supine rest. The complications of hypertension were not more closely related to BP during upright submaximal and peak exercise than to resting BP, and exercise BP did not contribute independently from BP at rest to their variance. In conclusion, exercise BP is not better related to target organ damage than BP at rest in patients with essential hypertension.

Adolescent↗
PubMed1990

Renal effects of cadmium body burden of the general population.

In a cross-sectional population study to assess whether environmental exposure to cadmium is associated with renal dysfunction, 1699 subjects aged 20-80 years were studied as a random sample of four areas of Belgium with varying degrees of cadmium pollution. After standardisation for several possible confounding factors, five variables (urinary excretion of retinol-binding protein, N-acetyl-beta-glucosaminidase, beta 2-microglobulin, aminoacids, and calcium) were significantly associated with the urinary excretion of cadmium (as a marker of cadmium body burden), suggesting the presence of tubular dysfunction. There was a 10% probability of values of these variables being abnormal when cadmium excretion exceeded 2-4 micrograms/24 h. Excretion reached this threshold in 10% of non-smokers. There was also evidence that diabetic patients may be more susceptible to the toxic effect of cadmium on the renal proximal tubule.

Acetylglucosaminidase↗
PubMed1990

[Hemodynamic effects of urapidil in men].

In hypertensive patients as well as in normal subjects, urapidil has a hypotensive action. This is mainly mediated by a peripheral alpha adrenoceptor blockade with a decrease in systemic vascular resistance. In addition, acute animal experiments demonstrated a centrally mediated hypotensive action, possibly by 5-hydroxytryptamine1A-receptor stimulation. Studies in humans showed an increase in cardiac output, which was not always significant; it resulted 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 non-significantly. A small reduction in pulmonary artery pressure and capillary wedge pressure was 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 flows were shown to increase and vascular resistance to decrease significantly after an acute intravenous doses of urapidil. The hemodynamic changes that occur during chronic therapy are largely unknown, except for systemic vascular resistance which remains decreased.

Antihypertensive Agents↗