Effect of pregnancy on paroxysmal supraventricular tachycardia.
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Biomedical subjects
A Dyer
Publications and source records attributed to A Dyer.
Inconsistent associations of caffeine-containing beverages with blood pressure and with lipoproteins. The CARDIA Study. Coronary Artery Risk Development in Young Adults.
The authors examined associations of caffeine and caffeinated beverage intakes with blood pressure and with lipoproteins in 5,115 black and white men and women aged 18-30 years during 1985-1986. Caffeine and beverage intakes were not consistently associated with blood pressure in analyses controlling for race, sex, Keys score, sucrose intake, physical activity, oral contraceptive use, body mass index, alcohol use, age, and smoking. Associations of caffeine and beverage intakes with cholesterol, triglycerides, high-density lipoprotein cholesterol, and high-density lipoprotein2 cholesterol were also inconsistent. There is little or no association of caffeine with lipoproteins or with blood pressure in this cohort of healthy young adults.
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Treatment of Nippostrongylus brasiliensis in normal and SPF rats using tetramisole loaded into zeolite.
Administration to rats of tetramisole loaded into zeolite was more successful in killing adults of Nippostrongylus brasiliensis than the administration of tetramisole alone. The most successful treatment occurred in SPF (Specific Pathogen Free) rats dosed with tetramisole loaded into zeolite and no worms were present in this group at autopsy eight days post-infection. It is concluded that the slow release of drug from the zeolite matrix improved its efficacy, especially in removing worms from low-grade infections.
Aluminum Silicates↗
Higher blood pressure in adults with less education. Some explanations from INTERSALT.
An inverse association between social class and disease has frequently been reported; education, an indicator of social class, was negatively related to blood pressure in several studies. Reasons are not clear. INTERSALT, an international study on electrolytes and blood pressure, obtained data on years of education for 10,079 adults in 52 centers in 32 countries. Data presented here are for 47 centers, omitting five where the population in the sample had no education or no differences in educational level. Regression coefficients were calculated for the education-blood pressure association in each center. An inverse association was found for men in 28 centers and for women in 38. Center coefficients were combined to give a studywide estimate of that association. When adjusted only for age, systolic pressure in men was 1.3 mm Hg higher for 10 fewer years of education (p less than 0.05) and for women 4.5 mm Hg higher (p less than 0.001). However, when adjusted also for five lifestyle factors (24-hour sodium and potassium excretion, body mass index, alcohol intake, and smoking), these estimates were reduced by about one half, and the inverse association was no longer significant for men. Similar findings were obtained for diastolic pressure. Those with less education had on average higher sodium excretion, lower potassium excretion, greater body mass, and higher alcohol intake, all factors tending to increase blood pressure. Improvement of these factors, which help explain the differences in blood pressure related to years of education, has the potential to reduce the blood pressure disadvantage associated with lower socioeconomic status.
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The Bishops' Census of 1563: its significance and accuracy.
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Demography↗
Conditions other than underlying cause of death listed on death certificates provide additional useful information for epidemiologic research.
Conditions other than underlying cause of death listed on death certificates may provide useful information for epidemiologic research. We explored this possibility for any mention of diabetes, renal diseases, and pneumonia-influenza-bronchitis on death certificates from the Chicago Western Electric Study. When we used any mention, sufficient numbers of deaths for analyses of risk factor associations with diabetes (N = 47), renal diseases (N = 25), and pneumonia-influenza-bronchitis (N = 59) were available; analyses for these risk factors were not possible using underlying cause of death alone (N = 3, 6, and 16, respectively). Using Cox regression, we observed positive associations of age, systolic blood pressure, serum cholesterol, body mass index, and cigarettes smoked per day with any mention of diabetes or renal disease. Age, systolic blood pressure, and cigarettes smoked per day were positively related to any mention of pneumonia-influenza-bronchitis; serum cholesterol and body mass index were inversely related to this endpoint. Whether we identified cardiovascular disease deaths using underlying cause, other mention, or any mention, the relations of established major risk factors with 25-year mortality were similar.
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Findings of the International Cooperative INTERSALT Study.
INTERSALT, an international cooperative study on electrolytes and other factors related to blood pressure, found, in within-population analyses involving 10,079 persons, a significant positive association between 24-hour urinary sodium excretion and systolic blood pressure and between the sodium/potassium ratio and systolic blood pressure. These significant findings were derived from analyses for individuals from all 52 centers and from the 48 centers remaining when persons from four low sodium centers were excluded. Potassium excretion of individuals was significantly and independently related inversely to their systolic blood pressure. For men and women, both separate and combined, the relation between sodium and systolic blood pressure was stronger for older than younger adults, perhaps reflecting the result of longer exposure with age or diminished capacity to handle a sodium load. Relations between electrolyte excretion and diastolic blood pressure in individuals were weaker than for systolic blood pressure. Body mass index and heavy alcohol consumption of individuals were strongly and independently related to blood pressure. In cross-population analyses with n = 52 or n = 48, sample median sodium excretion was significantly and independently related to the slope of systolic blood pressure and diastolic blood pressure with age. Other ecological analyses yielded inconsistent results. Four isolated populations showed low sodium excretion, low sodium/potassium excretion, low body mass index, and low alcohol consumption; sample median blood pressures were low, there was little or no upward slope of blood pressure with age, and high blood pressure was rare or nonexistent.
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Blood pressure, stroke, and coronary heart disease. Part 1, Prolonged differences in blood pressure: prospective observational studies corrected for the regression dilution bias.
The associations of diastolic blood pressure (DBP) with stroke and with coronary heart disease (CHD) were investigated in nine major prospective observational studies: total 420,000 individuals, 843 strokes, and 4856 CHD events, 6-25 (mean 10) years of follow-up. The combined results demonstrate positive, continuous, and apparently independent associations, with no significant heterogeneity of effect among different studies. Within the range of DBP studied (about 70-110 mm Hg), there was no evidence of any "threshold" below which lower levels of DBP were not associated with lower risks of stroke and of CHD. Previous analyses have described the uncorrected associations of DBP measured just at "baseline" with subsequent disease rates. But, because of the diluting effects of random fluctuations in DBP, these substantially underestimate the true associations of the usual DBP (ie, an individual's long-term average DBP) with disease. After correction for this "regression dilution" bias, prolonged differences in usual DBP of 5, 7.5, and 10 mm Hg were respectively associated with at least 34%, 46%, and 56% less stroke and at least 21%, 29%, and 37% less CHD. These associations are about 60% greater than in previous uncorrected analyses. (This regression dilution bias is quite general, so analogous corrections to the relations of cholesterol to CHD or of various other risk factors to CHD or to other diseases would likewise increase their estimated strengths.) The DBP results suggest that for the large majority of individuals, whether conventionally "hypertensive" or "normotensive", a lower blood pressure should eventually confer a lower risk of vascular disease.
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Sodium-lithium countertransport and systolic blood pressure response to exercise.
This study examined the relationship between erythrocyte sodium-stimulated lithium countertransport (Na-Li CT) and systolic blood pressure (SBP) response to exercise in 22 white normotensive men (mean age 40.6 years) completing a submaximal (85% of target heart rate) graded exercise tolerance test. These men were assessed to be at risk of hypertension on the basis of a high normal diastolic blood pressure (DBP; 80-89 mmHg), being overweight and having a rapid resting pulse rate. Na-Li CT was positively and significantly associated with the maximal SBP reached during exercise (P less than 0.01) and the lowest SBP achieved during post-exercise supine rest (P less than 0.01). The relationship with resting blood pressure was not significant. Standing DBP was the only resting blood pressure measurement significantly associated with Na-Li CT (P less than 0.05). We found an association between Na-Li CT, a membrane sodium transport system associated with blood pressure and hypertension, and the maximal SBP reached during exercise, a blood pressure measurement predictive of future hypertension, in people with normotensive resting blood pressure. This suggests that altered membrane sodium transport may occur before the establishment of hypertension, and supports the possibility that Na-Li CT may be a risk factor for this disease.
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Is Italy losing the "Mediterranean advantage?" Report on the Gubbio population study: cardiovascular risk factors at baseline. Gubbio Collaborative Study Group.
The coronary heart disease mortality rate in Italy--lower than in many other industrialized countries--has changed little in the last 20 years, whereas in the United States, a major decline in deaths resulting from coronary heart disease has occurred. These differing trends have reduced considerably the gap between the two countries in coronary mortality rates. Several recent population studies in Italy have found a change in the previously more favorable risk factor profile. In the northern hill town of Gubbio, studied in 1983-1985, median serum cholesterol level of men ages 40-59 was 223 mg/dl, considerably higher than was found in the 1960 Italian population samples of the Seven Countries Study (197-206 mg/dl). In the earlier study, the cholesterol levels in the Italian men who were still mainly consuming the traditional Mediterranean diet were 30-40 mg/dl lower than in the U.S. sample. The 1980 Gubbio levels, however, were at least as high as those of their U.S. contemporaries. Cigarette smoking was much higher among the middle-aged men of Gubbio than among a similar U.S. population sample (56% vs 36%). Hypertension prevalence was high, and several risk factors for hypertension--obesity, high salt intake, and alcohol--were common in the Gubbio as well as in other recent Italian population studies. The changing coronary risk profile in Italy, which now includes higher population levels of serum cholesterol as well as the other major coronary heart disease risk factors of cigarette smoking and hypertension, threatens to reduce markedly the "Mediterranean advantage" enjoyed by Italy in the past.
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Ethnic differences in blood pressure, pulse rate, and related characteristics in young adults. The CARDIA study.
This study examined ethnic differences in blood pressure and pulse rate in young adults to see whether the differences, if they exist, can be explained by differences in body mass index, lifestyle, psychological, and socioeconomic characteristics. Data used were from the baseline examination of the Coronary Artery Risk Development in (Young) Adults Study (CARDIA). CARDIA is a longitudinal study of lifestyle and evolution of cardiovascular disease risk factors in 5,116 young adults, black and white, men and women, aged 18-30 years, of varying socioeconomic status. Young black adults had higher mean systolic blood pressure and slightly higher mean diastolic blood pressure than young white adults. For both men and women, the blood pressure differences between blacks and whites tended to be greater for the age group 25-30 than for the age group 18-24 years. Among the variables studied, body mass index, duration of exercise on the treadmill, number of cigarettes smoked per day, and number of alcoholic drinks per week were consistently associated with blood pressure. The blood pressure differences were greatly reduced after adjusting for these variables. Black participants had lower mean pulse rate than white participants. The differences tended to be greater for the age group 18-24 than for the age group 25-30 years. Among the variables studied, only duration on treadmill and number of cigarettes smoked per day were consistently correlated with pulse rate. With adjustment for duration on treadmill, the differences in pulse rate increased. These results suggest that differences in ethnic pattern of blood pressures and pulse rate with age may be due in part to obesity, physical fitness, alcohol consumption, and cigarette smoking.
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INTERSALT study findings. Public health and medical care implications.
INTERSALT found a significant association between 24-hour urine sodium excretion and systolic blood pressure in individuals. There was also a significant association between sodium and slope (increase) of blood pressure with age across population samples. The weight of evidence from animal-experimental, clinical, intervention, and epidemiological data favors a causal relation. INTERSALT data from 52 centers in 32 countries permit an estimate of effect on average population blood pressure of lower sodium intake. Based on the sodium-blood pressure association in individuals, it was estimated that a habitual population sodium intake that was lower by 100 mmol/day (e.g., 70 vs. 170 mmol/day) would correspond to an average population systolic pressure that was lower by at least 2.2 mm Hg. This size difference in systolic blood pressure in major US and UK population studies is associated with 4% lower risk of coronary death and 6% lower risk of stroke death in middle age. If habitual diet is both lower in sodium and higher in potassium with lower alcohol intake and less obesity, INTERSALT data estimate average population systolic pressure would be lower by 5 mm Hg. This was calculated to correspond to a 9% lower risk of coronary death and a 14% lower risk of stroke death. INTERSALT cross-population data also suggest that, with a 100 mmol/day lower sodium intake over the life span, the average increase in population systolic pressure from age 25 to 55 years would be less by 9 mm Hg, corresponding at age 55 to a 16% lower risk of subsequent coronary death and 23% lower risk of stroke death.(ABSTRACT TRUNCATED AT 250 WORDS)
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The INTERSALT study: main results, conclusions and some implications.
INTERSALT is an epidemiological study of electrolyte excretion and blood pressure in 10,079 men and women from 52 centres and 32 countries. The data were collected according to strict protocol with extensive quality control, and were analysed both in individuals and across centres. In the individual analysis, with adjustment for confounding variables, significant positive associations were observed between blood pressure and twenty-four hour sodium excretion, body mass index and alcohol intake, and significant negative associations between blood pressure and potassium excretion. For a number of reasons, it is likely that the size of these relationships was underestimated. Across centres, linear slope of blood pressure with age was positively related to median sodium excretion. These observations imply that a policy combining changes in sodium and potassium intake with reductions in obesity and alcohol consumption could bring important public health benefits.
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The INTERSALT study: results for 24 hour sodium and potassium, by age and sex. INTERSALT Co-operative Research Group.
The relations by age and sex of urinary sodium, potassium and sodium/potassium ratio to blood pressure were examined in the 5,045 men and 5,034 women of the INTERSALT Study. With adjustment for age, and combining (pooling) regression coefficients over the 52 centres of the study, sodium excretion was positively and significantly related to the blood pressure of individuals in both men and women. These positive and significant relationships were also found in seven of eight age-sex specific analyses. In most analyses, z-scores suggested stronger associations in women than in men: the size of regression coefficients in women was as much as twice that of the corresponding coefficients in men. In age-specific analyses for men and women combined, sodium excretion was positively related to blood pressure, significantly so for systolic pressure at all ages and for diastolic pressure at ages 50-59; regression coefficients tended to be larger at older compared to younger ages. Results for sodium/potassium ratio in individuals were similar to those for sodium, being stronger in women than in men, and (at least for systolic pressure) at older compared to younger ages. With adjustment for confounding variables, potassium excretion was negatively and significantly related to the blood pressure of individuals; again these relationships tended to be more marked at older ages. Across the centres, median sodium excretion was positively and significantly related to the slope of systolic and diastolic blood pressure with age in men, in both the 52 and 48 centre analyses, and with and without adjustment for confounding variables.(ABSTRACT TRUNCATED AT 250 WORDS)
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Major and minor electrocardiographic abnormalities and risk of death from coronary heart disease, cardiovascular diseases and all causes in men and women.
The independent contributions of baseline major and minor electrocardiographic (ECG) abnormalities to subsequent 11.5 year risk of death from coronary heart disease, all cardiovascular diseases and all causes were explored among 9,643 white men and 7,990 white women aged 40 to 64 years without definite prior coronary heart disease in the Chicago Heart Association Detection Project in Industry. At baseline, prevalence rates of major ECG abnormalities were higher in women than in men, with age-adjusted rates of 12.9 and 9.6% (p less than 0.01), respectively. Minor ECG abnormalities were more common in men than in women (7.3 versus 4.5%, p less than 0.01). Both major and minor ECG abnormalities were associated with an increased risk of death from coronary heart disease, all cardiovascular diseases and all causes. The strength of these associations was greater in men than in women. When baseline age, diastolic pressure, serum cholesterol, cigarettes smoked per day, diabetes and use of antihypertensive medication were taken into account, major abnormalities continued to be significantly related to each cause of death in both genders with much larger adjusted absolute excess risk and relative risk for men than for women. In multivariate analyses, minor ECG abnormalities contributed independently to risk of death in men, but not clearly so in women. The results indicate the independent association between ECG abnormalities and mortality from coronary heart disease, all cardiovascular diseases and all causes, with greater relative significance in middle-aged United States men than women.
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Nutritional therapy for high blood pressure. Final report of a four-year randomized controlled trial--the Hypertension Control Program.
A four-year trial assessed whether less severe hypertensives could discontinue antihypertensive drug therapy, using nutritional means to control blood pressure. Randomization was to three groups: group 1--discontinue drug therapy and reduce overweight, excess salt, and alcohol; group 2--discontinue drug therapy, with no nutritional program; or group 3--continue drug therapy, with no nutritional program. In groups 1 and 2 patients resumed drug therapy if pressure rose to hypertensive levels. Loss of at least 4.5 kg (10 + lb) was maintained by 30% of group 1, with a group mean loss of 1.8 kg (4 lb); sodium intake fell 36% and modest alcohol intake reduction was reported. At four years, 39% in group 1 remained normotensive without drug therapy, compared with 5% in group 2. Study findings demonstrated that nutritional therapy may substitute for drugs in a sizable proportion of hypertensives or, if drugs are still needed, can lessen some unwanted biochemical effects of drug treatment.
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The role of relative weight in the positive association between age and serum cholesterol in men and women.
With advancing age from youth on, there is an increase in mean serum cholesterol level of populations in "western" industrialized countries. Since serum cholesterol is one of the established major risk factors for premature coronary heart disease, it is important to explore the degree to which this age trend is physiologic or due to modern life styles. This study used cross-sectional data for 19,730 white men and 13,872 white women from the Chicago Heart Association Detection Project in Industry to investigate one aspect of this question: does weight explain the association between age and serum cholesterol, in particular whether older age is associated with higher serum cholesterol in the absence of overweight. The relationships among age, relative weight, and serum cholesterol were examined through assessment of mean serum cholesterol levels in 25 subgroups stratified by age (18-24, 25-34, 35-44, 45-54, 55-64) and by relative weight (less than 100, 100-109, 110-119, 120-134, greater than or equal to 135). Age and serum cholesterol were positively associated with each other. In women, it was a simple, linear relationship. In men, the degree of this positive association was less in people over age 35-44 than people in younger ages. These age-cholesterol patterns were present in men and women at desirable weight. However, in men aged 18-54, the positive association between age and prevalence of marked hypercholesterolemia (serum cholesterol greater than or equal to 250) was lower in people at desirable relative weight in comparison to those at higher relative weight.(ABSTRACT TRUNCATED AT 250 WORDS)
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Sex differential in the relationship of electrocardiographic ST-T abnormalities to risk of coronary death: 11.5 year follow-up findings of the Chicago Heart Association Detection Project in Industry.
The independent contributions of ST segment depression and/or T wave abnormality (ST-T abnormalities) on the baseline resting electrocardiogram to risk of 11.5 year coronary heart disease (CHD) mortality were explored among 9203 white men and 7818 white women who were 40 to 64 years old and without definite CHD at entry in the Chicago Heart Association Detection Project in Industry. At baseline, prevalence rates of ST-T abnormalities were age related for both sexes, and at every age the rate was higher in women than men (age-adjusted prevalence rates 12.3% and 8.1%, respectively). Univariate analysis showed that ST-T abnormalities were associated with significantly increased risk of death from CHD for both men and women. However, men with ST-T abnormalities had much greater age-adjusted and multiple risk factor-adjusted absolute excess risk and relative risk than women with such electrocardiographic abnormalities. When baseline age, diastolic pressure, serum cholesterol, cigarettes/day, history of diabetes, and baseline use of antihypertensive medication were included in the multivariate analysis, ST-T abnormalities remained significantly related to death from CHD in men but not women. The interaction term between sex and ST-T abnormalities was at a borderline level of statistical significance by Cox regression analysis. In conclusion, ST-T abnormalities indicate an increased risk of subsequent death from CHD independent of major coronary risk factors for middle-aged U.S. men, but this is not clearly so for women.
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