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Biomedical subjects

J Staessen

Publications and source records attributed to J Staessen.

At least 55 records · Page 3Linked to original sources
PubMed1994

Influence of cholesterol lowering on plasma membrane lipids and cationic transport systems.

BACKGROUND: In order to determine whether alterations in membrane lipids affect transmembrane cationic transport systems in erythrocytes and platelets, cationic fluxes and intracellular cationic concentrations were measured in hypercholesterolaemic patients before and during administration of an inhibitor of 3-hydroxy-3-methlglutaryl coenzyme A reductase. METHODS: After a 1-month run-in placebo period on a lipid-lowering diet the patients were treated, in a double-blind manner, with either placebo (n = 25) or pravastatin (n = 25) for 6 months. Placebo or pravastatin (10 mg during the first month, 20 mg during the second month and 40 mg during the remaining 4 months) was administered once a day in the evening. RESULTS: Compared with the placebo group, the erythrocyte and platelet membrane cholesterol content was reduced in the patients treated with pravastatin. The intra-erythrocyte and intraplatelet Na+ concentration was reduced during pravastatin administration, whereas the activity of the erythrocyte and platelet Na(+)-K+ pump was increased. However, the intra-erythrocyte and intraplatelet K+, Mg2+ and cytosolic Ca2+ concentrations, and water content, as well as the activities of the erythrocyte Na(+)-Li+ countertransporter and Na+,K+ cotransporter, and Na+ and K+ leakage, were not changed during pravastatin treatment. CONCLUSIONS: The present data show that cholesterol lowering in hypercholesterolaemic patients may result in a significant decrease in erythrocyte and platelet membrane cholesterol content. These changes in membrane cholesterol are accompanied by an increase in activity of the Na(+)-K+ pump and a decrease in intra-erythrocyte and intraplatelet Na+ concentrations.

Biological Transport↗
PubMed1994

Mechanical and other factors relating to left ventricular hypertrophy.

Although the development of left ventricular hypertrophy in hypertension is explained as a response to increases in pressure load and wall tension, the relationship between left ventricular mass and conventional blood pressure is usually weak. This may be due to the lack of standardization and the small number of blood pressure measurements in some studies. However, even 24-h blood pressure monitoring can explain only around 25% of the variation in left ventricular mass, and repeated blood pressure measurements over 30 years have not proved better in this respect. Therefore, other factors have been considered, including anthropometric and demographic characteristics; genetic influences; differences in salt intake, physical activity and alcohol consumption; neurohumoral factors; duration of hypertension; and previous antihypertensive treatment. Antihypertensive treatment may reduce left ventricular mass and a number of prospective, randomized, comparative studies have assessed whether some (classes of) drugs are more effective than others. A meta-analysis of such studies, comparing diuretics, beta-blockers, calcium antagonists and/or angiotensin-converting enzyme (ACE) inhibitors, suggests that the reduction of left ventricular mass with each of these classes is similar to the reduction obtained with the other three classes statistically combined. Of particular interest is the observation that the four studies which specifically compared an ACE inhibitor and a calcium antagonist concluded that their effects on left ventricular mass did not significantly differ. Furthermore, that agents such as minoxidil and hydralazine do not reduce left ventricular mass.

Antihypertensive Agents↗
PubMed1993

Implications for trials in progress of publication of positive results.

It is not easy to decide, when results from similar trials appear, whether a trial still underway should be stopped or not. The weight of the other evidence has to be taken into account--as indeed it has to be for decisions by clinicians and by health service managers outside the settings of a trial. Taking the Systolic Hypertension in the Elderly Trial (SHEP) as an example, we show how its results are not unequivocal (ie, there is no proof beyond reasonable doubt). This verdict justifies the continuation of similar trials in progress. More generally--but again for individual clinicians and for trial organisers and again with SHEP as the example--we illustrate a bayesian approach to trial-termination decisions.

Aged↗
PubMed1993

Response of ambulatory blood pressure to antihypertensive therapy guided by clinic pressure.

The objective of this prospective study was to define the limits below which ambulatory blood pressure (BP) does not decrease in patients with essential hypertension, when the decision to institute and intensify drug treatment is based on conventional blood pressure measurements. After a 1 month placebo run-in period, 30 patients were treated for 1 year with the converting enzyme inhibitor lisinopril or the calcium antagonist isradipine; dose adjustments and the decision to add hydrochlorothiazide were based on conventional blood pressure measurements in the clinic. Ambulatory blood pressure was recorded during 24 h in the run-in period and after 16, 24, and 52 weeks of active therapy. The baseline ambulatory blood pressure below which pressure does, on average, not decrease during active treatment was defined as the pressure at which the regression line between the on-treatment pressure and blood pressure in the run-in period intersects the line of identity. The systolic/diastolic blood pressure limits were similar for the three assessments during active treatment and averaged 128/88 mm Hg for daytime, 106/73 mm Hg for nighttime pressure, and 119/81 mm Hg for the whole 24 h, with upper 95% confidence limits of 137/93, 115/78, and 127/86 mm Hg, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Smoking and blood pressure in the leg.

OBJECTIVES: To determine whether the calf:brachial ratio for systolic blood pressure is reduced in both current and ex-smokers of cigarettes. DESIGN: Cross-sectional study of the calf:brachial systolic blood pressure ratio and smoking history. SUBJECTS: Four hundred and ten male and 138 female civil servants aged 35-59 years working in the Department of the Environment Building, London. RESULTS: In men the systolic blood pressure ratio (Doppler calf:auscultatory brachial) decreased above the age of 50 years. However, different patterns were observed in those who had smoked at some time and those who had never smoked. In those who had never smoked the ratio in men aged 35-44 years was lower than that in men aged 55-59 years. In those who had smoked the average ratio rose from the age of 35-44 years to the age of 45-49 years and then fell to below the former value at the age of 55-59 years. There was a significant difference between lifelong non-smokers and current smokers at age 55-59 years. The pattern was similar in both male ex- and current smokers, and ex-smokers had results intermediate between those for current smokers and those who had never smoked. In women who had never smoked the ratio increased from the age of 35-44 years to the age of 50-59 years. In women aged 50-59 who currently smoke or used to smoke cigarettes the average ratio was close to that for women aged 35-44 years who had never smoked. CONCLUSIONS: The calf:brachial systolic blood pressure ratio is a simple measurement that may prove useful in detecting the early adverse effects of smoking on peripheral vascular disease. Lower ratios at older ages occurred in both current and ex-smokers, and the effects of smoking on peripheral arterial disease may not be easily reversible at older ages.

Adult↗
PubMed1993

Does isradipine modified release 5 mg once daily reduce blood pressure for 24 hours?

Twelve patients with essential hypertension were randomized in a double-blind cross-over study to investigate the blood pressure BP-lowering activity of isradipine regular formulation (RF) 2.5 mg twice daily (between 7 and 8 a.m. and at approximately 6 p.m.), and isradipine modified release (MR), 5 mg once daily (between 7 and 8 a.m.). The two randomized treatment periods were separated by a placebo period. Patient compliance was similar between placebo and isradipine RF and MR treatment. As compared with placebo, isradipine RF decreased daytime BP by 10 mm Hg systolic (SBP, p < 0.001) and by 6 mm Hg diastolic (DBP, p < 0.01), and night SBP and DBP by 7 (p < 0.05) and 3 mm Hg (P = NS), respectively. Isradipine MR reduced the daytime SBP 8 mm Hg (p < 0.05) and DBP by 3 mm Hg (p = NS), and the night SBP by 1 mm Hg (p = NS) and DBP by < 1 mm Hg (P = NS). Analysis of variance showed that the interaction terms between the effects of treatment and time of day were not significant for SBP (F = 1.56, p = 0.24) or DBP (F = 1.40, p = 0.26) with isradipine RF treatment, but they were significant for SBP (F = 6.33, p = 0.03) and DBP (F = 5.12, p = 0.04) with isradipine MR treatment. Therefore, the BP-lowering effect of isradipine MR 5 mg once daily appears to weaken as the day progresses.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Influence of antihypertensive drugs on exercise capacity.

Both single dose and short term diuretic treatment adversely affect maximal exercise capacity and the duration of prolonged submaximal exercise. However, insufficient data are available to establish the effect of long term diuretic treatment on exercise capacity. beta-Blockade reduces maximal aerobic power by approximately 7%. In addition, the capacity for prolonged submaximal exercise appears to be markedly impaired in normotensive and hypertensive patients, particularly when nonselective beta-blockers are prescribed. Fewer data are available for other drugs, but, whatever the mechanism of vasodilation, drugs that reduce systemic vascular resistance do not seem to have any effect on exercise capacity.

Antihypertensive Agents↗
PubMed1993

The older hypertensive. Assessment and treatment.

A meta-analysis is presented of 8 therapeutic trials in elderly hypertensive patients. In an intention-to-treat analysis, cardiovascular mortality was decreased on average by 22% (95% confidence interval ranging from -32% to -10%). This decrease was explained by both a reduction in coronary mortality by 26% (-40% to -9%) and in cerebrovascular mortality by 33% (-50% to -9%). The effectiveness of therapy in terms of reducing cardiovascular mortality is not established with confidence in those trials where the diastolic blood pressure at randomization is below 95 mmHg or in the patients above 75 years of age. A goal blood pressure is not definitively established, but a reduction of the systolic blood pressure to about 150 mmHg may be optimal. Extrapolation of the trial results to the elderly population with systolo-diastolic hypertension at large seems acceptable for the western population, but may be premature for the Asian and African elderly. Beta-blockers and especially diuretics are recommended as first-line drugs in elderly patients with symptomless, uncomplicated hypertension, since the effectiveness of other drugs in reducing morbidity and mortality is not yet established. Recommendation for treatment of symptomless patients with isolated systolic hypertension may be premature. The ongoing Syst-Eur and Syst-Chin trials may provide further information.

Aged↗
PubMed1993

Nitrendipine in older patients with isolated systolic hypertension: second progress report on the SYST-EUR trial.

This report from the double-blind placebo-controlled SYST-EUR trial investigated whether modern antihypertensive drugs are suitable for maintaining long-term BP control in older (> or = 60 years of age) subjects with isolated systolic hypertension (SBP 160-219 mmHg and DBP < 95 mmHg). Active treatment consisted of nitredipine (10-40 mg/day) with the possible addition of enalapril (5-20 mg/day) and hydrochlorothiazide (12.5-25 mg/day), if necessary to reduce SBP to < 150 mmHg and by > or = 20 mmHg. Matching placebos were used in the control group. This analysis was restricted to 18 months of follow-up. The placebo (n = 456) and active treatment (n = 485) groups had similar characteristics at randomisation (sitting pressure 176/85 mmHg; age 73 years). SBP fell (P < 0.001) on average 10 mmHg more on active treatment than on placebo and DBP 4 mmHg more. Fewer patients remained on monotherapy in the placebo than in the active treatment group (P < 0.001); on placebo the second and third line medications were started earlier (P < 0.001). Nitrendipine tablets were discontinued in nine patients on placebo and in 29 patients assigned to active treatment (P < 0.001). In conclusion, a significant BP reduction can be achieved and maintained in older patients with isolated systolic hypertension treated with a calcium antagonist (associated with a converting-enzyme inhibitor and a thiazide, where necessary). Whether this BP reduction results in a clinically meaningful decrease of cardiovascular complications is under investigation.

Aged↗
PubMed1993

APTH--a trial on ambulatory blood pressure monitoring and treatment of hypertension: objectives and protocol.

Study is to test the hypothesis that antihypertensive treatment based on ambulatory monitoring may be more beneficial than treatment guided by conventional sphygmomanometry. After a 2 month run-in period on placebo, eligible hypertensive patients (sitting diastolic pressure > 95 mm Hg on conventional measurement) will be randomized into 2 groups, one in which the target pressure is a sitting diastolic pressure from 80 through 89 mm Hg on conventional sphygmomanometry, and one in which a daytime (from 10 to 20 h) ambulatory diastolic pressure from 80 through 89 mm Hg should be achieved. For 6 months following randomization, treatment consisting of lisinopril 10-20 mg per day, associated with 12.5 mg hydrochlorothiazide and 5 mg amlodipine, as necessary, will be stepwise adjusted in order to reach the goal pressure. During this period of the trial the doctor making the therapeutic decisions at the Coordinating Office will be kept blinded with respect to the type of measurement guiding therapy. A final period of 4 months, during which treatment will be adjusted by the patient's personal physician according to the current recommendations, concludes the trial. The outcome measures include the blood pressure level on conventional and ambulatory measurement, the amount of drugs required to achieve the goal blood pressure, side-effects evaluated by a self-administered questionnaire and left ventricular mass as assessed by electrocardiography and echocardiography.

Amlodipine↗
PubMed1993

Health effects of environmental exposure to cadmium in a population study.

The Cadmibel Study is a cross-sectional population study, which investigated the hypothesis that environmental exposure of the population to cadmium would result in health effects. The 2,327 participants constituted a random sample of the population of four Belgian districts, chosen to provide a wide range of environmental exposure to cadmium. The urinary cadmium excretion, a measure of lifetime exposure, averaged 9.3 nmol/24h in men (range 0.4-325 nmol/24h) and 7.2 nmol (0.1-71 nmol/24h) in women. The Cadmibel Study refuted the hypothesis that exposure to cadmium would lead to an increase in BP and in the prevalence of hypertension and other cardiovascular diseases. Serum alkaline phosphatase activity and the urinary excretion of calcium correlated significantly and positively with urinary cadmium in both sexes. These findings suggest that the calcium metabolism is gradually affected, as cadmium accumulates in the body. Furthermore, several markers of renal tubular function (urinary excretion of retinol binding protein, N-acetyl-beta-glucosaminidase, beta 2-microglobulin and aminoacids) were significantly and positively associated with urinary cadmium. There was a 10% probability of abnormal values of these markers of tubular function when urinary cadmium exceeded +/- 20 nmol/24h. However, the morbidity associated with the functional changes, observed in the Cadmibel Study, remains presently unknown and requires further investigation, preferably in a longitudinal population studies.

Adult↗
PubMed1992

The increase in blood pressure with age and body mass index is overestimated by conventional sphygmomanometry.

This cross-sectional study investigated whether the technique of blood pressure measurement used (conventional sphygmomanometry vs. ambulatory monitoring) affects the relation between blood pressure and both age and body mass index. Two independent data sets were analyzed. The first comprised 328 subjects (48% men) drawn from the population of a small Belgian town, and the second comprised 776 Irish bank employees (51% men). Age ranged from 17 years to 81 years, and body mass index (weight (kg)/height (m)2) ranged from 16.6 to 40.2. Twenty-four-hour ambulatory blood pressure was lower than blood pressure measured by a nurse in both the Belgian population sample (118/71 mmHg vs. 122/73 mmHg) and the Irish employees (118/72 mmHg vs. 119/76 mmHg). When blood pressure was measured by an observer, the well-established relations between systolic and diastolic blood pressure and both age and body mass index were evident. When the analyses were repeated using 24-hour measurements, the increment (cross-sectionally assessed) in blood pressure with age was weaker, especially in young and middle-aged subjects (20-60 years), while the increase in blood pressure with body mass index was also reduced. The within-subject differences between the conventional and ambulatory blood pressure measurements increased with older age and greater body mass index. Several other relations with blood pressure as the response variable may require revision in light of the present findings.

Adult↗
PubMed1992

Treatment of the older hypertensive: paradigms, practices, and proofs.

Recent outcome trials in patients above age 60 with systolo-diastolic hypertension are reviewed. The meta-analysis suggests that antihypertensive drug therapy can decrease cardiovascular and coronary mortality in selected patients. Based on these studies it is suggested that antihypertensive drug therapy is indicated in patients between age 60 and 75 when the diastolic pressure remains above 95 mmHg after repeated measurements. A target for systolic b.p. is not definitely established but a pressure of 150 mmHg may serve as a temporary proposal. Whether uncomplicated isolated systolic hypertension in symptomless patients should be treated is still under investigation.

Aged↗
PubMed1992

Twenty-four hour blood pressure monitoring in the Syst-Eur trial.

This article describes the objectives and protocol of a study on ambulatory blood pressure in elderly patients with isolated systolic hypertension. This study constitutes an optional side-project to the Syst-Eur trial. The multicentre Syst-Eur trial investigates whether antihypertensive treatment of elderly patients with isolated systolic hypertension will influence the incidence of stroke. Secondary endpoints include cardiovascular events, such as myocardial infarction. The main objective of the side-project is to investigate whether ambulatory blood pressure monitoring will improve the prediction of cardiovascular complications based on blood pressure measurement in the clinic. The side-project also provides the opportunity to evaluate the diurnal profile of blood pressure in elderly patients with isolated systolic hypertension randomized to placebo or active antihypertensive treatment.

Aged↗