Dietary Calcium Intake and Blood Pressure in Normotensive Subjects

ABSTRACT. Epidemiological and prospective studies in man and animals have indicated an inverse relationship between calcium intake and cardiovascular mortality and blood pressure (BP). We have therefore studied the effect of dietary calcium on blood pressure in two groups of women. In a cross-sectional study 103 early postmenopausal women were stratified into three groups according to daily calcium intake calculated from a questionnaire. Both diastolic and systolic blood pressures were identical in the three groups. We thereafter conducted a prospective placebo-controlled trial on the effect of calcium supplementation. Twenty-eight healthy women were randomized to placebo treatment (n=14) or calcium supplementation 2000 mg daily (n=14) for one year. In both groups BP remained at initial levels throughout the study and was identical in the two groups at measurements every three months. We thus conclude that calcium supplementation has no effect on BP in normotensive subjects on a high calcium diet.     

体重指数、腰围／臀围比与血压、血脂的相关性

本研究于１９９３年在北京地区抽取２５～６４岁的男女两性１２８２人，分析了体重指数（ＢＭＩ）、腰围／臀围比（ＷＨＲ）与血压、血脂的相关性。结果显示：男女两性的ＢＭＩ和ＷＨＲ均随年龄的增加而增加；男性ＷＨＲ显著高于女性（Ｐ＜０．００１），而ＢＭＩ无性别差异（Ｐ＝０．０６）。控制其它危险因素后，ＢＭＩ与男女两性的舒张压正相关；ＷＨＲ与血压的相关无显著性。ＢＭＩ、ＷＨＲ均与血脂独立相关，ＷＨＲ与血脂的相关性强于ＢＭＩ与血脂的相关性。本研究结果提示：ＢＭＩ反映的是调整身高后的体重值，它与血压的相关性较强；ＷＨＲ反映的是脂肪分布，它与血脂的相关性较强。此结果对高血压、高脂血症的防治具有重要的指导意义。     

Atrial Natriuretic Factor and Ambulatory Blood Pressure in Young Male Subjects with Normal or Borderline Office Blood Pressure

Plasma levels of immuno-reactive atrial natriuretic factor (ANF) and ambulatory blood pressure were studied in 42 male subjects, aged 18 to 31 y, including 24 subjects with normal BP and 18 with borderline essential hypertension. ANF was measured in the morning (9 a.m.-12 a.m.), with the subjects in the supine and in the upright positions. Ambulatory BP was determined in all subjects every 15 minutes, for a whole 24 hour period. A scatter plot of office SBP or DBP versus upright or supine ANF suggested     

Transdermal Clonidine Therapy and Blood Pressure Nocturnal Fall in Mild Hypertensive Male Subjects

Treatment of mild hypertension with an antihypertensive drug administered by means of a transdermal therapeutic system (TTS) could produce favorable results, when compared with a traditional oral regimen. Purpose: Using 24-h ambulatory blood pressure (BP) monitoring (ABPM) in mild hypertensive male subjects, to analyze three aspects which have not been completely clarified: a) whether a latency in the antihypertensive effect may be present, recording BP already from the first day of application of the patch, b) the eventual hazardous enhancement of circadian nocturnal fall in BP values in treated mild hypertensive patients and, c) the possible overlapping of antihypertensive effect between the administration of two consecutive patches. Subjects and methods: In 12 caucasian male outpatients (yrs 55 ± 3 SEM) with uncomplicated essential mild hypertension, a patch containing placebo was applied for the first week (T 0 period). At the end of the T 0 period, a 5 mg TTS-2 clonidine patch was applied for one week, and, subsequently, a new patch of 5 mg TTS-2 clonidine was kept for another week. ABPM was performed on the last day of the placebo period (T 0) and on the 1st day (T1), the 7th day (T2) and the 14th day (T3) of transdermal clonidine therapy. Results: Both systolic and diastolic BP (24 h mean, day-night-time) decreased on the 1st, 7th and 14th day, when compared with T0. However, no significant differences were documented between the BP levels on the 1st and the 7th day of treatment. The incidence of nocturnal fall in systolic and diastolic BP was evaluated and no significant differences were found, when compared with night-time reference values. Conclusions: When compared with the placebo period, TTS-2 clonidine lowers SBP and DBP within the first 24 hours of application. The antihypertensive effect persists at the end of the first week, as well as after 14 days. The lowest values of systolic-diastolic BP documented were not below the levels reported in normotensive men. Therefore, TTS-2 clonidine seems to act as an antihypertensive agent rather than a hypotensive drug since it normalizes BP without lowering it below physiological levels.     

Prediction of Stable High Blood Pressure in Adolescents

We studied the relative importance of the initial BP and associated factors in adolescents to predict stable high BP. Out of 17.634 children aged 12-13 yrs an upper group the upper 5% of the distribution curves for both SBP and DBP/ a lower group/10% random from the remainder/were yearly fallowed for 4 yrs/boys: 1680, girls: 1643/. About 2/3 of children remained at the same percentile point: < 30% and ≥ 70% of SBP and half of them of DBP distribution. Significant positive tracking correlations were found both for SBP and DBP between the initial BP and follow-up BP readings in the same individual. Stepwise regression analysis showed that the SBP taken at the fourth follow-up can be explained by 29% in boys, 24% in girls on the basis of screening SBP and by 47% in boys, 42% in girls on the basis of SBP measured at the four previous examinations. Using discriminant analysis, 6-9 variables out of 18 studied could correctly allocate adolescents with stable SBP or DBP/< 70% or ≥70% at least 3 examinations/. Our study shows the importance of initial BP and a number of factors associated with stable high BP.     

Relation Between Weight and Body Fat's Distribution and Ambulatory Blood Pressure in Chinese Elderly

Ninety-five subjects aged 60 years and over underwent casual and ambulatory blood pressure (BP) measurements as well as weight, height, both waist and hip circumferences and both upper arm and thigh circumferences. Most anthropometric variables were significantly correlated with measures of BP. One stepwise regression analysis was applied to reveal that among measures of BP, 24-hour systolic BP had the strongest correlation with waist/hip ratio and awaking diastolic BP the strongest correlation with weight, both waist and hip circumferences and body mass index. Another was used to show that waist/hip ratio was the best overall predictor of systolic BP and weight the best overall predictor of diastolic BP. We suggest     

Ambulatory Blood Pressure: A Predictor of Left Ventricular Mass and Future Blood Pressure in Subjects Predisposed for Hypertension

Twenty-four-hour ambulatory blood pressure (SpaceLab 5200) and a single laboratory blood pressure were measured in a population-derived sample of normotensive men (mean age 36 years) with (n = 13) or without (n = 16) a positive family history of hypertension. The aim was to determine whether ambulatory monitoring was a better predictor than clinical measurements for echocardiographic derived indices of left ventricular mass and for future blood pressure. At the initial examination ambulatory blood pressure could discriminate between the groups, showing significant differences that were not evident from the clinical blood pressure measurement. After 5 years the blood pressure had increased in the group with a family predisposition for hypertension but only one subject had overt hypertension. The correlation between the average day-time blood pressure and the clinical blood pressure at follow-up was only marginally better than the correlation for the initial clinical blood pressure. In contrast to the clinical blood pressure, both day-time and night-time blood pressure averages were significantly correlated to left ventricular mass at the initial examination. It is concluded that in still normotensive subjects, ambulatory monitoring is a better predictor than clinical measurements for left ventricular mass but not for future blood pressure.     

Physiologic Increase and Tracking of Blood Pressure in Schoolchildren

4343 blood pressure (BP) recordings were obtained in 1575 school-children during 5 years. Systolic BP rose proportionally to upper arm muscle area (MA) in both sexes. In contrast, upper arm fat area (FA) was considerably lower in boys than in girls, and the rise of systolic BP in boys during puberty was not accompanied by any increase of FA.

Atrepeat examination of 900 children after 1 to 5 years, between 35% and 53% of those with initial systolic BP in the highest quintile had again values in the same quintile, thus twice as often as expected. Tracking in the highest decile was even stronger: 37% of 82 children had again systolic BP in the highest decile at 2 years, and 29% at 4 to 5 years. - We conclude that 1) the physiologic increase of systolic BP is primarily determined by rising muscle mass, and 2) tracking still remains detectable in children after 4 to 5 years and is strongest in those with highest values.     

Fractal Dimension of Heart Rate and Blood Pressure in Healthy Subjects and in Diabetic Subjects

Beat-to-beat heart rate (HR) and blood pressure (BP) were measured by the Finapres system in 28 healthy subjects and 64 diabetic subjects. Autonomic controls in diabetic subjects were assessed by scoring 5 cardiovascular function tests (high score = abnormal control). The fractal dimension (FD) of HR (or SBP) was estimated as follows: Measuring the curve of 500 successive HRs with a rule of length L, one obtains N times L. The FD is the slope of the regression line of Log(N) versus Log(I/L) for different L. We found a lower FD of HR in diabetic subjects than in healthy subjects (1.35 ± 0.10/1.44 ± 0.09, p = 0.0002) and a similar FD of SBP in the 2 groups. In diabetic subjects, the FD of HR was negatively correlated with age (r = -0.27, p = 0.03), duration of diabetes (r= -0.33,p = 0.0078) and score of disautonomy (r= -0.43,p = 0.0007). So, heartbeat is more fractal in healthy status: a low fractal fluctuation is a sign of pathology.     

Body composition and bone mineral density in long-standing type 1 diabetes

OBJECTIVES: To study body composition and bone mineral density (BMD) in adult patients with long-standing type 1 diabetes mellitus. RESEARCH DESIGN AND METHODS: In a population-based study, body composition and BMD were evaluated by dual energy X-ray absorptiometry in 38 patients with type 1 diabetes since childhood, compared with 38 age- and sex-matched controls. The mean age was 43 years (range 33-55 years) and the mean duration of diabetes was 33 years (range 28-37 years). RESULTS: Besides a tendency to a reduced abdominal fat mass in diabetic males, no difference was observed in fat mass, muscle mass, or BMD between the groups. Significant correlations were found between insulin dosage and whole body fat mass in diabetic females and between serum cholesterol levels and abdominal fat mass in diabetic males. CONCLUSION: Patients with long-standing type 1 diabetes with onset in childhood and adolescence seem to show only minor differences in body composition and no difference in BMD compared with closely matched healthy controls.     

盐敏感性高血压病患者的胰岛素抗性与应激血压反应特点

目的观察盐敏感者胰岛素抗性与应激血压反应的关系。方法对３３例高血压病患者和２７例血压正常对照者用静脉盐水负荷和速尿缩容相结合的方法确定盐敏感性（ＳＳ）基础上，进行糖耐量、胰岛素释放试验；精神激发，冷加压和运动等试验。结果ＳＳ与盐不敏感者（ＳＲ）比较，空腹及糖负荷后各时点血糖及胰岛素含量均明显增高，胰岛素敏感指数降低（Ｐ均＜０．０５）；空腹血胰岛素在百分位Ｐ７５以上者或胰岛素敏感指数在百分位Ｐ２５以下者，精神激发及冷加压后平均动脉压上升幅度（ΔＭＡＰ）明显增加，且与空腹血胰岛素水平呈正相关（ｒ值分别为０．３８１及０．４２３，Ｐ＜０．０５），与胰岛素敏感指数呈负相关（ｒ值为－０．３９３和－０．２６７，Ｐ＜０．０５）。结论盐敏感者有胰岛素抗性增加的表现，且与应激血压明显增强相关联     

Risk Factors Associated with High Blood Pressure in Two-to Five-Year-Old Children

Background

Over recent decades, the prevalence of high blood pressure (BP) has increased among children. Several risk factors are involved in the genesis of high BP during childhood, and their early identification can prevent the development of that disease.

Objectives

To assess the prevalence of high BP and associated factors in children.

Methods

Cross-sectional, population-based study, carried out at the household. This study included 276 two- to five-year-old children in the city of Goiânia, state of Goiás, and assessed their BP, sociodemographic characteristics, birth weight, high BP family history, passive smoking, maternal breastfeeding, dietary habits, sedentary lifestyle and nutritional status. Poisson regression was used to assess the association between risk factors and high BP.

Results

Their mean age was 3.1 ± 0.79 years, and high BP and overweight were observed in 19.9% and 11.2% of the children, respectively. Direct association of high BP was identified with age [prevalence ratio (PR) = 2.3; 95%CI: 1.2 - 4.8; p = 0.017] and overweight (PR = 2.0; 95%CI: 1.2 - 3.6; p = 0.014). No other variable associated with high BP.

Conclusions

The prevalence of high BP in children was high. Overweight and younger children had greater prevalence of high BP.     

Antiendothelial Cell Antibody Levels in Healthy Normotensives with High Normal Blood Pressure

High normal blood pressure (HNBP) seems to be related to an increased cardiovascular risk in healthy normotensive subjects. According to the literature, elevated levels of antibodies against endothelial cell surface antigen antiendothelial cell antibodies (AECA) play an important role in the early stages of atherosclerosis process and in borderline hypertension. The aim of this study was to compare AECA levels of healthy normotensives with HNBP to those of healthy normotensives with normal blood pressure (NBP), matched for age, sex, and body mass index (BMI).

Methods. Ninety healthy normotensives with HNBP (43M, 47F; mean age, 48 ± 2.6 yrs; BMI 23.6 ± 1.5 Kg/m²) (Group A) and 80 healthy normotensives with NBP (41M, 39F; mean age, 46 ± 3 yrs; BMI 24 ± 1.8 Kg/m²) (Group B) were studied. Both group subjects were matched for sex, age, and BMI. AECA levels were determined in each subject using an enzyme-linked immunosorbent assay (ELISA). AECA levels were expressed as mean values. Results. Twenty-five subjects from group A (28%) showed elevated IgG antiendothelial cell antibodies levels vs. three from group B (3.75%, p < 0.001). IgM AECA levels were elevated in 18 subjects from group A (20%) vs. two from group B (1.5%, p < 0.001). Conclusions. The present findings suggest that healthy normotensives with HNBP have significantly higher AECA levels of both classes (IgG, IgM) compared to healthy normotensives with NBP. This may have prognostic significance for the future development of essential hypertension in this group of healthy subjects.     

A Method to Define Reference Profiles for Ambulatory Blood Pressure,with Application to Blood Pressure Profiles in 158 Young Subject

ABSTRACT

Ambulatory blood pressures (systolic, SBP, diastolic, DBP) and heart rate were determined over 24h every 15min in the day and every 15min in the night in 72 normal subjects aged 21±1SEM with normal casual office pressures (WHO's criteria: officeDBP ≤ 90mmHg, officeSBP ≤ 140mmHg) and in 86 essential hypertensive subjects aged 21±1, with borderline office pressure (WHO's criteria: officeDBP ≤ 95mmHg, officeSBP ≤ 160mmHg). Complete 24-hour profiles (mean±SD) were reported. In the average, mean ambulatory DBP in the normal group was about 72.5mmHg in “day time” (9 a.m.-9 p.m.) and 63.5mmHg in “night time” (midnight-7 a.m.). Ambulatory SBP in the normal group were about 126mmHg and 110mmHg for the same time periods. In the borderline hypertensive group, the figures were 74mmHg (day-time) and 67mmHg (night time) for diastolic pressure and 140mmHg (day time) and 118mmHg (night time) for systolic pressure. However, when the normal and borderline groups were defined as above on the basis of office pressures, ambulatory blood pressure profiles in the two groups showed a large overlap. A method was proposed to reduce this overlap by partially reallocating the subjects on the basis of ambulatory blood pressure. First, a typical profile was defined for each group and a distance was defined between two arbitrary profiles. Then a subject in the normal (resp. hypertensive) group was reallocated to the hypertensive (normal) group if his profile was closer to the typical profile of the hypertensive (normal) group than the typical profile of his own group. Applied to ambulatory DBP profiles, this method reallocated 49 subjects (over the total of 158), significantly reduced the initial overlap of BP profiles between the two groups, and defined reference profiles for “normal” and “borderline” ambulatory blood pressures.     

Changes in 24 Hour Blood Pressure and in Cardiac and Vascular Structure in Normotensive Subjects with Parental Hypertension

Subjects with family history of hypertension represent a suitable model to investigate the mechanisms responsible for early cardiovascular structural and functional changes occurring in essential hypertension. In our study we have addressed the factors involved in determining the mild elevation in office blood pressure frequently observed in normotensive subjects with hypertensive parents. In 15 normotensive subjects with both parents hypertensive (FH++) and in 15 normotensive subjects with one parent hypertensive (FH+?) we found no evidence of a hyperreactivity to stress as compared to the responses of 15 normotensive subjects with no parental hypertension (FH–). On the contrary FH++ subjects were characterized by a significant although mild increase in their blood pressure values recorded either at rest and in ambulatory conditions over the 24 hours, including night sleep. FH++ and FH+? subjects also showed a greater left ventricular mass thickness and a greater minimal forearm vascular resistence than FH subjects. Thus, the elevation in blood pressure found in the pre-hypertensive stage in subjects with positive family history for hypertension does not reflect a hyperreactivity to the stress associated with physician's visit but indicates an early and persistent blood pressure elevation. This blood pressure elevation is accompanied by early cardiovascular structural changes which may indicate that these subjects are exposed to a higher risk even before developing overt hypertension.     

Epidemiological Perspective of Body Position and Arm Level in Blood Pressure Measurement

According to official recommendations, indirect blood pressure (BP) measurement should be performed in the brachial artery at heart level in the seated position. At lower levels the hydrostatic pressure of the column of blood in between the heart and the point of measurement is added. The clinical relevance of deviations from the recommendations was investigated in a population-based sample of 401 healthy men and women of ages 15-84 years. In the seated position, the systolic BP measured with the upper arm parallel to the sternum was higher than that with the forearm elevated at heart level. The difference was 9.4 (SD 6.6) mm in men and 8.2 (6.9) mm in women. The corresponding differences in diastolic BP were 13.6 (4.4) mm in men and 12.4 (4.5) mm in women. At heart level, the supine systolic BP was 7.9 (7.5) mm higher than the seated in men, and 8.2 (8.0) mm higher in women, while the diastolic BP was the same up to the age of 40. It is concluded that deviations from the recommended body position and arm level are clinically relevant. The pattern of discrepancy, falsely high BPs below the heart level and a higher pulse pressure in the supine position, is uniform in both sexes at all adult ages.     

Vagal Enhancement Linking Abnormal Blood Pressure Response and Subendocardial Ischemia in Hypertrophic Cardiomyopathy

An abnormal blood pressure response to exercise has been reported to be associated with left ventricular subendocardial ischemia in patients with hypertrophic cardiomyopathy (HCM), but the underlying mechanism remains unclear. We report a case of HCM with an abnormal blood pressure response and subendocardial ischemia, in which the analysis of heart rate variability revealed exercise‐induced vagal enhancement. The present case highlights the possible mechanism linking abnormal blood pressure response and left ventricular subendocardial ischemia in patients with HCM.     

The Genetic Control of Blood Pressure and Body Composition in Rats with Stress-Sensitive Hypertension

The genetic basis of the stress-sensitive arterial hypertension was investigated using the quantitative trait loci (QTL) approach. Two groups of F₂ (inherited stress-induced arterial hypertension [ISIAH] × Wistar albino Glaxo [WAG]) hybrid males of different age (3–4 months old and 6 months old) were tested for blood pressure at rest and stressed conditions and for body composition traits. Several novel loci for the traits were determined. Some loci for blood pressure and organ weight were mapped to the same genetic region in rats of different age. The dynamic change of QTL effects in two rat groups of different age might reflect the process of stress-sensitive hypertension development.