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Biomedical subjects

J A Staessen

Publications and source records attributed to J A Staessen.

At least 127 records · Page 7Linked to original sources
PubMed1996

Public health implications of environmental exposure to cadmium and lead: an overview of epidemiological studies in Belgium. Working Groups.

The CadmiBel Study was a cross-sectional population study that investigated the health effects of environmental exposure to cadmium and lead. The 2327 participants constituted a random sample of the population of four Belgian districts, chosen in order to provide a wide range of environmental exposure to cadmium. After adjustment for confounding factors, such as smoking and occupational exposure, the urinary cadmium excretion, a measure of lifetime exposure, was nearly 30% higher in the polluted areas. The CadmiBel Study produced evidence inconsistent with the hypothesis that environmental exposure to cadmium and lead would lead to an increase in blood pressure and to a higher prevalence of hypertension and other cardiovascular diseases. On the other hand, the serum alkaline phosphatase activity and the urinary excretion of calcium were significantly and positively correlated with urinary cadmium in both sexes. These findings suggested that the homeostasis of calcium was gradually affected as cadmium accumulated in the body. Furthermore, several markers of renal tubular dysfunction (urinary excretion of retinol-binding-protein, N-acetyl-beta-glucosaminidase, beta 2-microglobulin and amino acids) were significantly and positively associated with urinary cadmium. Across 10 small areas of which six were polluted with cadmium, an inverse association existed between the creatinine clearance and several indexes of environmental exposure to cadmium (cadmium concentration in the soil, cadmium content of locally grown vegetables, the inhabitants' 24 h urinary cadmium excretion). In the CadmiBel Study, the creatinine clearance was also inversely correlated with the concentrations of lead and zinc protoporphyrin in the blood. Thus, environmental exposure to cadmium and lead was associated with alterations in renal function. The significance in terms of morbidity and mortality of the functional disturbances observed in the CadmiBel Study, and the possible strategies to prevent the transfer of cadmium from the environment to man are under investigation in the prospective PheeCad Study in which half of the Cadmibel participants have been enrolled (participation rate 80%).

Adult↗
PubMed1996

Treatment of hypertensive patients according to the conventional or ambulatory pressure: a progress report on the APTH trial. APTH Investigators. Ambulatory Blood Pressure and Treatment of Hypertension.

The main objective of the Ambulatory Blood Pressure and Treatment of Hypertension (APTH) trial 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 single-blind placebo, hypertensive patients were randomized to two groups, one in which the target pressure was a sitting diastolic pressure from 80 through 89 mm Hg on conventional sphygmomanometry (conventional blood pressure [CBP] group), and one in which a daytime (from 10 to 20 h) diastolic pressure from 80 through 89 mm Hg had to be achieved (ambulatory blood pressure [ABP] group). After randomization all patients were started on lisinopril 10 mg/day. One month later lisinopril could be continued at 10 or 20 mg/day or discontinued depending on the attained blood pressure level. This article is an interim report on 207 patients followed for two months into the trial. At one month lisinopril was discontinued more frequently in the ABP than the CBP group (24 vs 9 patients, p = 0.004). Nevertheless at two months, blood pressure control was not significantly different in the two treatment groups. The baseline-adjusted differences in systolic pressure between the two treatment arms of the trial (ABP-CBP group) were +2.7 mm Hg (95% confidence interval [CI]): -2.9, +8.3) for the conventional pressure, +0.4 mm Hg (CI: -4.3, +5.1) for the 24 h pressure, -0.1 mm Hg (CI: -5.1, +4.8) for the daytime pressure and -0.7 mm Hg (CI: -6.7, +5.4) for the night-time pressure. The corresponding differences in diastolic pressure were -1.3 mm Hg (CI: -4, +1.4), +0.1 mm Hg (CI: -3, +3.1), -1.1 mmgH (CI: -4.4, +2.1) and +0.3 mm Hg (CI: -3.7, +4.3), respectively. Thus, the present findings do not refute the APTH research hypothesis. In terms of blood pressure control and the number of patients remaining on antihypertensive drugs, treatment based on ambulatory recordings may be preferable to treatment guided by conventional sphygmomanometry.

Antihypertensive Agents↗
PubMed1996

Associations of orthostatic blood pressure fall in older patients with isolated systolic hypertension. Syst-Eur Investigators.

OBJECTIVES: To investigate the associations of the orthostatic blood pressure changes in older patients with isolated systolic hypertension. METHODS: A total of 2716 patients, 917 men and 1799 women, aged > or = 60 years, were examined at three separate outpatient visits whilst receiving placebo during the single-blind run-in phase of the Syst-Eur trial. The orthostatic blood pressure changes were calculated by subtracting the average of two blood pressure readings with the patient in the supine position from the mean of two readings obtained after the patient had stood for 2 min. An orthostatic blood pressure drop by at least 20 mmHg systolic or 10 mmHg diastolic was considered exaggerated. RESULTS: For the three run-in visits combined, the supine blood pressure was 175 +/- 13 mmHg systolic and 86 +/- 6 mmHg diastolic (means +/- SD). With the patients standing the systolic blood pressure was 5 +/- 12 mmHg lower, whereas the diastolic blood pressure was 2 +/- 7 mmHg higher. An exaggerated fall in systolic blood pressure was observed on at least 1 visit in 21.0% of the patients and on all three visits in 2.5%. The corresponding values for diastolic blood pressure were 9.7 and 0.4%. The orthostatic fall in systolic blood pressure increased with previous antihypertensive treatment, age and smoking, but decreased with a higher sitting pulse rate and usual alcohol consumption versus none. The rise in diastolic blood pressure upon standing was higher in women than in men, was curvilinearly associated with age and increased with the sitting diastolic blood pressure. By multiple logistic regression analysis, the odds of having a persistent or occasional exaggerated orthostatic fall in systolic blood pressure were 22% higher in women than in men. The odds increased with previous antihypertensive treatment (by 42%), age (by 1.4%/year), electrocardiographic left ventricular mass (by 15%/mV) and sitting systolic blood pressure (by 0.9%/mmHg), but decreased with sitting pulse rate (by 1.9%/beat per min). An exaggerated orthostatic fall in diastolic blood pressure was 30% more likely in men; the likelihood increased with age (by 6.4%/year) and decreased with sitting diastolic blood pressure (by 6.6%/mmHg). CONCLUSION: An exaggerated orthostatic blood pressure fall in older patients with isolated systolic hypertension is associated mainly with gender, age and blood pressure level. Previous antihypertensive treatment, a lower pulse rate and a lower electrocardiographic left ventricular mass were also associated with an exaggerated orthostatic fall in systolic blood pressure.

Age Factors↗
PubMed1996

Prevalence and persistency of orthostatic blood pressure fall in older patients with isolated systolic hypertension. Syst-Eur Investigators.

Postural hypotension in older people has been the subject of many studies, but there remains some doubt as to its true prevalence. This study investigated the prevalence and persistency of an exaggerated orthostatic blood pressure (BP) fall in a large group of older patients with isolated systolic hypertension. A total of 2716 patients, 917 men and 1799 women, whose age ranged from 60-100 years, were examined at three separate outpatient visits on a placebo in the single-blind run-in phase of the Syst-Eur Trial. The supine and standing BPs at each visit were the averages of two readings. An exaggerated BP fall was defined as a drop in systolic pressure by at least 20 mm Hg 2 min after assuming the standing from the supine position, or as a drop in the diastolic pressure by at least 10 mm Hg. The reproducibility of orthostatic BP changes was evaluated by the Bland and Altman technique. With the three run-in visits combined, the sitting pressure averaged ( +/- standard deviation) 174 +/- 11 mm Hg systolic and 86 +/- 6 mm Hg diastolic. Systolic pressure fell on average by 5 +/- 12 mm Hg from the supine to the standing position, whereas diastolic pressure increased by 2 +/- 7 mm Hg. The percentage of patients showing an exaggerated orthostatic BP fall was constant at each of the three run-in visits, ie 11-12% for systolic pressure and 4% for diastolic pressure. An exaggerated BP fall at each of the three run-in visits was only present in 3% of the patients for systolic pressure and in 0.4% for diastolic pressure. An exaggerated BP fall at the run-in visits was not associated with dizziness and syncope, which occurred in only 1% of the patients. The orthostatic fall in systolic, but not diastolic pressure, was greater (0.6 mm Hg; P < 0.05) at the second than at the first visit. The repeatability coefficients tended to be higher (60-65%), signifying lower reproducibility, than those for the BP levels (45-55%). An exaggerated fall in systolic or diastolic pressure may occasionally occur in nearly 10% of older patients with isolated systolic hypertension even without antihypertensive drug therapy, but a persistent orthostatic response in only rarely observed.

Aged↗
PubMed1995

Once-daily antihypertensive treatment with calcium antagonists: utopia or reality?

Although a large number of antihypertensive drugs have been approved for once- or twice-daily dosing, no standardized set of evidence is required to demonstrate that the blood pressure reduction is sustained for 24 h. The recent literature on calcium antagonists was therefore searched for the arguments usually put forward to objectify a long duration of action. Most studies relied on ambulatory blood pressure monitoring. However, several published reports were difficult to interpret for a variety of reasons, such as: (1) a non-blinded non-randomized study design; (2) a statistical analysis, which was discordant with the study design; (3) analyses confined to the 24 h, day-time and night-time pressure means; (4) the absence of a baseline adjustment and/or formal statistical testing; (5) the "post hoc" subdivision of patients into responders and non-responders; and (6) the absence of a well-specified time-frame linking drug intake to the observed antihypertensive effects. According to the authors' interpretation, amlodipine, diltiazem SR (modified release), felodipine SR, isradipine SR, nifedipine SR, nitrendipine and verapamil SR have all been confirmed to reduce both the conventional and the 24 h blood pressure. Some studies went beyond the 24 h blood pressure means and also presented separate results for the day-time (or awake) and night-time (or sleeping) periods, or investigated the blood pressure reduction at the end of the dosing interval, or compared the diurnal blood pressure profiles on different treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure Monitoring, Ambulatory↗
PubMed1995

The relationships between left ventricular mass and daytime and night-time blood pressures: a meta-analysis of comparative studies.

OBJECTIVE: To review the literature to examine critically the assertion that night-time blood pressure is a better predictor of echocardiographic left ventricular mass than daytime blood pressure, and that left ventricular mass is inversely related to the day-night blood pressure difference. STUDY SELECTION: Published studies in which left ventricular mass (index) of normotensive or hypertensive individuals, or both, was related to automated blood pressure measurement during the day and night, or their difference, or both. RESULTS OF DATA ANALYSIS: The meta-analysis of 19 comparative studies, involving 1223 participants, indicates that the weighted correlation coefficient for the relationship between left ventricular mass (index) and systolic night-time blood pressure (0.44; 95% confidence limit 0.39-0.48) is not significantly different from the correlation with systolic daytime blood pressure (0.48; 95% confidence limit 0.44-0.52; P > 0.2). The corresponding correlation coefficients for diastolic blood pressure both average 0.37. In half of the eight studies in which the association between left ventricular mass (index) and the day-night difference in blood pressure was analysed, investigators found no significant relationship between those variables; in the others, the variance of the mass (index) that can be explained by the blood pressure difference is 15% at the most. CONCLUSION: The overall analysis suggests that night-time blood pressure is not a significantly better predictor of left ventricular mass than daytime blood pressure is, and that the relationship to the day-night blood pressure difference is not a unanimous finding and is only ever weakly significant.

Blood Pressure↗
PubMed1995

A consensus view on the technique of ambulatory blood pressure monitoring. The Fourth International Consensus Conference on 24-Hour Ambulatory Blood Pressure Monitoring.

This review, based on the Fourth International Consensus Conference on Ambulatory Blood Pressure Monitoring (Leuven, Belgium, 1994), deals with the technical aspects of ambulatory blood pressure monitoring. Ambulatory blood pressure monitoring by noninvasive intermittent techniques is widely used despite artifacts due to cuff size, movement, body position, short-term blood pressure variability, and interference with sleep. The performance of the currently available monitors under truly ambulatory conditions and during exercise remains a matter of debate, as are the procedures required to validate portable monitors under these circumstances. There is general agreement that whenever a monitor is to be used in special populations, such as older subjects or pregnant women, or in special conditions, such as exercise, a specific demonstration of its accuracy in these defined subgroups or conditions is warranted. Whether the auscultatory or oscillometric method is preferred remains controversial because each technique has specific advantages and disadvantages and because both can provide accurate results. Most experts in the field strongly believe that manufacturers should disclose the algorithms of their devices and that they should specify all changes made to the hardware and software of a previously validated monitor. Finally, the development of the volume-clamp method, which makes continuous noninvasive registration of blood pressure at the finger possible in both stationary and ambulatory conditions, opens new perspectives in research, in particular in relation to short-term blood pressure variability.

Adult↗
PubMed1995

The trough-to-peak ratio as an instrument to evaluate antihypertensive drugs. The APTH Investigators. Ambulatory Blood Pressure and Treatment of Hypertension Trial.

The U.S. Food and Drug Administration designed the trough-to-peak ratio as an instrument for the evaluation of long-acting antihypertensive drugs, but the ratios are usually reported without accounting for interindividual variability. This study investigated how the trough-to-peak ratio would be affected by interindividual and intraindividual variability and by smoothing of the diurnal blood pressure profiles. The ambulatory blood pressure was recorded on placebo in 143 hypertensive patients (diastolic pressure on conventional measurement > 95 mm Hg). After 2 months, the recordings were repeated on 10 mg (n = 66) or 20 mg (n = 77) lisinopril given once daily between 7 and 11 PM. The baseline-adjusted trough-to-peak ratios were determined from diurnal blood pressure profiles with 1-hour precision. Lisinopril reduced (+/- SD) the 24-hour pressure by 16 +/- 17 mm Hg for systolic and 10 +/- 10 mm Hg for diastolic (P < .001). According to the usual approach, disregarding interindividual variability, the trough-to-peak ratio was 0.72 for systolic pressure and 0.67 for diastolic pressure. In the 143 patients the ratios were not normally distributed. They were the same on both lisinopril doses. When interindividual variability was accounted for, the median trough-to-peak ratio was 0.34 (P5 to P95 interval, -0.46 to 0.87) for systolic pressure and 0.26 (-0.44 to 0.84) for diastolic pressure. In 66 patients examined twice on 10 mg lisinopril at a median interval of 32 days, the trough-to-peak ratios were characterized by large intraindividual variability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Trough-to-peak versus surface ratio in the assessment of antihypertensive agents. APTH Investigators. Ambulatory Blood Pressure and Treatment of Hypertension.

This study investigated whether the 'surface ratio', a novel index to characterize long-acting antihypertensive agents, would provide a more reproducible estimate of the duration of the antihypertensive effect than the more commonly used trough-to-peak ratio. In 66 hypertensive patients (diastolic pressure on conventional measurement > 95 mmHg), the ambulatory blood pressure was measured on a placebo at baseline and 2 months later, while the patients took 10 mg lisinopril once a day between 7 p.m. and 11 p.m. Diurnal treatment effect curves were obtained by subtracting the blood pressure at baseline from the corresponding value at 2 months for all time intervals considered in the analysis. In order to calculate the surface ratio, the area under the treatment effect curve was divided by the product of the maximal blood pressure lowering effect and the dosing interval (24 h). Reproducibility of the trough-to-peak and surface ratios was investigated by the Bland and Altman techniques. At 2 months, lisinopril reduced (+/- standard deviation) the 24 h pressure by 13 +/- 16 mmHg systolic and by 8 +/- 8 mmHg diastolic (p < 0.001). According to the usual approach, disregarding inter-individual variability, the trough-to-peak ratio was 0.7 for systolic and diastolic pressure. When in individual patients diurnal treatment effects curves with a 1 h resolution were investigated, the median trough-to-peak ratio was 0.30 for systolic pressure (5th-95th percentile interval [PI]: -0.51, 0.82) and 0.28 for diastolic pressure (PI: -0.37, 0.78); the corresponding values for the surface ratio were 0.33 (PI: 0.03, 0.58) and 0.30 (PI: -0.01, 0.55). In the same manner, the trough-to-peak ratios and surface ratios became larger when the individual blood pressure profiles were progressively smoothed by substituting 1 h averages by 2 h moving averages, 2 h averages, 3 h moving averages or by 3 h averages. The distributions of the trough-to-peak ratios and surface ratios were non-normal in 37 of 40 instances (p < 0.001, Shapiro-Wilk's test). Consistency was higher (p < 0.001) for the surface than for the trough-to-peak ratios. The within-subject reproducibility of the surface ratios tended to be superior to that of the corresponding trough-to-peak ratios. In conclusion, the surface ratio provides an index of the duration of action of antihypertensive agents. Moreover, in the present patients, the surface ratio tended to be characterized by a higher within-subject reproducibility than the trough-to-peak ratio.

Adult↗
PubMed1995

Low-level lead exposure and blood pressure.

The possible association between low-level lead exposure and blood pressure (BP) remains debated. The purpose of this review was: (1) to determine whether the available studies in humans support a positive association, in particular at lower exposure levels (blood lead concentration < 1 mumol/l), and (2) to explore whether animal studies and the proposed pathophysiological mechanisms are supportive of a positive and causal association between lead exposure and hypertension. A meta-analysis of 23 studies included 33,141 subjects recruited from the general population in 13 surveys and from occupational groups in 10 studies. In all but four studies the results had been adjusted for age, and most studies also considered additional confounders. The association between BP and blood lead was similar in both sexes. In all 23 studies combined, a two-fold increase in blood lead concentration was associated with a 1 mm Hg rise in the systolic pressure (CI 0.4-1.6 mm Hg; P = 0.002) and with a 0.6 mm Hg increase in the diastolic pressure (CI 0.2-1.0 mm Hg; P = 0.02). Of 21 animal studies, one was carried out in dogs, one in pigeons and the remainder in various rat strains. In 15 studies, in which the lead dose in drinking water or food exceeded 1 p.p.m. the association between BP and exposure was found to be positive in seven, inconsistent in three, absent in four and negative in one. Of the six studies at lower exposure levels (< or = 1 p.p.m.), five found a pressor effect attributable to lead. Whether the lead doses in the animal studies are equivalent to the human exposure levels and to what extent one can extrapolate from genetically heterogeneous animals to humans, remains doubtful. If a causal relation between lead exposure and hypertension exists, the proposed mechanisms may include interference of lead with ion transport across cell membranes, interactions with calcium homeostasis and calcium-mediated processes, direct vasomotor actions and the potentiation of sympathetic stimulation. Interference of lead with the balance between the renin-angiotensin-aldosterone and the kallikrein-kinin systems and impairment of renal function are unlikely to be implicated. On balance, the published evidence suggests that there can only be a weak positive association between BP and lead exposure. The latter relation, which is barely visible at the horizon of epidemiological observation, may not be causal in nature and is unlikely to entail any public health implication in terms of hypertension-related complications.

Animals↗
PubMed1994

Clinical trials with ambulatory blood pressure monitoring: fewer patients needed? Syst-Eur Investigators.

We have tested the concept that fewer patients are needed in trials of antihypertensive treatment if blood pressure is measured by ambulatory monitoring rather than by conventional sphygmomanometry. 233 patients (> or = 60 years old) with isolated systolic hypertension were randomly allocated placebo (n = 119) or active treatment (n = 114). Blood pressure measurements were compared by Wilcoxon's test and blood pressure profiles by ANOVA. With either method of measurement, the same number of patients (40 in each treatment group) was required to show a reduction after 1 year in clinic (13/8 mm Hg) or average blood pressure over 24 h (9/5 mm Hg). To detect that the decrease in systolic pressure was not steadily maintained through the day, 40 patients in each treatment group were needed for blood pressure profiles made up of 4-hourly or 2-hourly means and 60 for profiles of 1-hourly means. For diastolic pressure, the corresponding numbers were 80, 100, and more than the number of available patients, respectively. We conclude that parallel-group trials focusing on the average blood pressure over 24 h, rather than on conventionally measured blood pressure, cannot economise on sample size. Moreover, trials studying the full course of blood pressure throughout the day, require more--not fewer--patients than studies of only the conventional or average 24 h blood pressure.

Aged↗
PubMed1994

Renal function and historical environmental cadmium pollution from zinc smelters.

We investigated whether there was an association between renal function and cadmium pollution in areas with different exposures. Cadmium was measured in the soil and in vegetables in 10 districts, 6 of which were close to zinc smelters; and renal function and the concentrations of metals in blood and urine were measured in 703 randomly selected residents. 6 polluted areas, compared with 4 others showed higher cadmium concentrations in the soil (4.86 vs 0.81 ppm) and in locally grown vegetables, such as celery (2.43 vs 0.68 ppm) and beans (0.42 vs 0.15 ppm). Residents in polluted areas had higher urinary cadmium (10.5 vs 7.9 nmol/24 hours) and copper (0.16 vs 0.14 mumol/24 hours); higher serum creatinine (100 vs 97 mumol/L) urinary excretions of beta 2-microglobulin (109 vs 95 micrograms/24 hours), retinol-binding-protein (136 vs 118 micrograms/24 hours), and N-acetyl-beta-glucosaminidase (1.78 vs 1.38 U/24 hours). Serum zinc (12.2 vs 12.6 mumol/L) and creatinine clearance (87 vs 92 mL/min) were reduced in the 6 polluted areas. In all 10 districts, cadmium in the soil was positively correlated with cadmium in celery (r = 0.77), in beans (r = 0.67), and in residents' urine (r = 0.76). The creatinine clearance was inversely correlated with cadmium in soil (r = -0.78), in celery (r = -0.90), and in beans (r = -0.70). Past emissions from zinc smelters gave rise to contamination of the environment with cadmium, which gets into the food chain and has the potential to cause renal dysfunction and alterations in zinc and copper homeostasis.

Adult↗
PubMed1994

Life style as a determinant of blood pressure in the general population.

This study investigated which life style factors were correlated with the level and the variability of systolic (SBP) and diastolic (DBP) pressure in a random population sample. Ten blood pressure readings were obtained at home in 405 men and 379 women (20 to 84 years). Each person's average pressure level was computed together with the standard deviation as index of variability. Sodium, potassium, and alcohol intake, smoking habits, social class, psychoemotional stress, and the calories spent at work and in sports were assessed from a questionnaire and from determinations on serum and on a 24-h urine sample. A P10 to P90 (10th and 90th percentile) increase of alcohol intake, as reflected by serum gamma-glutamyltransferase, was associated with a 3.2 +/- 0.9 mm Hg higher DBP in men and with a 3.1 +/- 1.6 mm Hg higher SBP and a 1.5 +/- 0.8 mm Hg higher DBP in women. A P10 to P90 increase in the calories spent in sports was accompanied by a decrease in pressure, averaging 1.5 +/- 0.8 mm Hg for DBP in men and 2.4 +/- 1.2 mm Hg and 1.8 +/- 0.8 mm Hg for SBP and DBP in women. A 2.2 +/- 0.7 mm Hg higher DBP was observed in women living in a working class area. After adjustment for age, the variability of DBP was inversely correlated with self-rated physical activity in men, whereas women living in a working class area showed a decreased SBP variability. In conclusion, in an affluent Western population, alcohol intake, participation in sports, and living in a working class area were identified as the life style factors of importance for the blood pressure level. By contrast, blood pressure variability, as measured in the present study, was only to a minor extent influenced by life style.

Adult↗
PubMed1994

Ambulatory blood pressure and blood pressure measured at home: progress report on a population study.

To determine reference values for ambulatory blood pressure, a population sample of 718 subjects (20 through 88 years old) was investigated. Ambulatory blood pressure was recorded over 24 h, taking measurements at 20-min intervals from 8 a.m. to 10 p.m. and at 45-min intervals from 10 p.m. to 8 a.m. Trained nurses also measured the conventional pressure at each participant's home. The ambulatory blood pressure in the 718 subjects averaged 119/71 mm Hg over 24 h, 125/76 mm Hg during the day (10 a.m.-8 p.m.), and 108/62 mm Hg at night (0 a.m.-6 a.m.). Compared with the daytime pressure, blood pressure at home was on average the same in all 718 subjects but was 3/1 mm Hg lower in 530 normotensive subjects. The 95th percentiles of the 24-h pressures were 134/85 mm Hg in 182 men below age 50, 145/87 mm Hg in 164 men aged > or = 50 years, 127/80 mm Hg in 198 women below age 50, and 141/81 mm Hg in 174 women aged > or = 50 years. In the normotensive subjects of these four strata, these percentiles were 132/82 mm Hg (n = 149), 128/80 mm Hg (n = 103), 125/79 mm Hg (n = 180), and 131/79 mm Hg (n = 98). In comparison with earlier results in a smaller sample (n = 318) from which treated patients were excluded, this analysis demonstrated consistent results in the determination of a reference frame for ambulatory monitoring. Nevertheless, the prognostic significance of such reference values needs to be established in longitudinal studies and clinical trials.

Adult↗
PubMed1994

Is a positive association between lead exposure and blood pressure supported by animal experiments?

The possible association between low-level lead exposure and blood pressure and the causal nature of any such relationship continue to be debated. A recent meta-analysis of the human model data showed that on average a doubling of blood lead was associated with a rise in blood pressure averaging 1 mm Hg systolic and 0.6 mm Hg diastolic. The older animal studies, however, failed to show a significant pressure increase with massive lead exposure. This review therefore attempts to determine whether the more recent animal studies are supportive of a positive association between lead exposure and blood pressure elevation. Of the 21 animal studies published since 1977, one was carried out in dogs, one in pigeons, and the remainder in various rat strains. In the articles in which all the lead doses had been higher than 1 ppm, the association between blood pressure and exposure was found to be positive in seven, inconsistent in three, absent in four, and negative in one. Of the six animal experiments that employed lead doses not exceeding 1 ppm, five reported a small pressor effect. One of these five positive low-dose studies, however, failed to show a dose-effect relationship when exposure was increased from 0.1 to 1 ppm. In conclusion, most, but not all animal studies published since 1977 found a positive association between blood pressure and lead exposure. However, publication bias may have inflated the number of positive studies appearing in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Psycho-emotional stress and salt intake may interact to raise blood pressure.

AIM: This study examined whether work-related aspects of stress, alone or in association with a high salt intake, are associated with a raised blood pressure. METHODS: A total of 384 male civil servants (35-51 years) collected a 24h urine sample and were interviewed using measures of work-related stress. Their blood pressure was taken at a civil-service medical clinic and was self-measured at home. RESULTS: Systolic/diastolic pressure averaged ( +/- SD ) 135 +/- 19/84 +/- 14 mmHg at the clinic and 123 +/- 16/80 +/- 11 mmHG on self-measurements at home. The 24h urinary sodium excretion was 172 +/- 65 mmol. The overall stress score was categorized as low in 98 men, medium in 193 men and high in 93 men. Stress itself was not associated with an elevated pressure. However, in multivariate analyses with adjustments for age and body mass index, a stress-sodium interaction in the determination of the clinic systolic (P = 0.05) and diastolic (P = 0.08) pressure became apparent. At a sodium excretion of 100 mmol/24h (10th percentile), increasing stress from low to high was associated with a fall in pressure, averaging 4.5 mmHg for systolic pressure and 1.4 mmHg for diastolic pressure. By contrast, at 250 mmol/24h (90th percentile) the same stress increase was associated with a rise in pressure of 6.3 mmHg systolic and 5.9 mmHg diastolic. CONCLUSION: The present study suggests that sodium intake and work-related stress may interact to determine blood pressure. This interaction is probably dynamic in nature, so that the contribution of each factor to blood pressure can only be determined if both are measured.

Adult↗
PubMed1994

Hypertension caused by low-level lead exposure: myth or fact?

BACKGROUND: Several reports on the possible association between low-level lead exposure and blood pressure reflect diverging views. This meta-analysis aimed to find a common denominator in the published literature and to estimate whether a relationship exists between blood pressure and levels of lead in the blood. METHODS: Of the studies reviewed, 23 provided sufficient details to be considered. The meta-analysis included 33 groups with a total of 33 141 subjects, who had been recruited from the general population in 13 surveys and from occupational groups in 10 studies. In all but four studies the results were adjusted for age, and most studies took into account additional confounding factors. RESULTS: The association between blood pressure and blood lead was similar in both men and women. In the combined studies, a twofold increase in blood lead concentration was associated with a 1.0 mmHg rise in systolic pressure (confidence interval 0.4-1.6 mmHg; P = 0.002) and with a 0.6 mmHg increase in diastolic pressure (confidence interval 0.2-1.0 mmHg; P = 0.02). The association with systolic pressure strongly relied on the inclusion of a large study (n = 3851) in which women's blood pressure was measured at the end of pregnancy. The association with diastolic pressure was largely due to a population survey in the USA (n = 6289). There was no relationship across studies between the strength of the blood pressure-blood lead relationship and the mean blood lead concentration. CONCLUSION: The published evidence suggests that there can only be a weak positive association between blood pressure and lead exposure. Any such relationship may not be causal and is unlikely to entail any public-health implication in terms of hypertension-related complications. Nevertheless, these assumptions need to be confirmed in prospective population studies.

Blood Pressure↗