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Biomedical subjects

R C Ellison

Publications and source records attributed to R C Ellison.

At least 55 records · Page 3Linked to original sources
PubMed1997

Bone mass and the risk of breast cancer among postmenopausal women.

BACKGROUND: Recent studies have shown a direct relation between serum estrogen levels assessed at a single point in time and the risk of breast cancer, but no evidence links estrogen levels assessed repeatedly over an extended interval to the risk of breast cancer. Bone mass has been proposed as a marker of cumulative exposure to estrogen in women. We therefore studied the association between bone mass and the incidence of breast cancer. METHODS: Between 1967 and 1970, 1373 women who were 47 to 80 years old and had no history of breast cancer underwent posteroanterior hand radiography in the Framingham Study. We used radiogrametry to measure the cortical width of each woman's second metacarpal. Participants were followed until the end of 1993. All incident cases of breast cancer were confirmed by pathological reports. We used a Cox proportional-hazards model to examine the relation of metacarpal bone mass to the risk of postmenopausal breast cancer. RESULTS: Postmenopausal breast cancer developed in 91 subjects. Incidence rates per 1000 person-years increased from 2.0 among the women in the lowest age-specific quartile of metacarpal bone mass to 2.6, 2.7, and 7.0 among the women in the second, third, and highest quartiles, respectively. After adjustments for age and other potential confounding factors, the rate ratios for the risk of breast cancer were 1.0, 1.3, 1.3, and 3.5 from the lowest quartile to the highest (P for trend, <0.001). CONCLUSIONS: Women in the highest quartile of bone mass are at higher risk for postmenopausal breast cancer than those in the lowest quartile. The mechanisms underlying this relation are not understood, but cumulative exposure to estrogen may play a part.

Aged↗
PubMed1997

Associations between candidate loci angiotensin-converting enzyme and angiotensinogen with coronary heart disease and myocardial infarction: the NHLBI Family Heart Study.

Angiotensin-converting enzyme (ACE) and angiotensinogen (AGT) are major components of the renin-angiotensin systems. An association between myocardial infarction (MI) and the ACE DD genotype of the insertion/deletion (ID) polymorphism in intron 16 of the ACE gene has been reported. However, other similarly designed studies have not found such an association. Angiotensin II, the product of AGT, has a direct effect on vascular tone; and a variant in the AGT gene has been found to be associated with MI in the Japanese. This case-control study was initiated to investigate whether the ACEI/D and AGT M235T polymorphisms are associated with an increased risk for coronary heart disease (CHD) and MI. Our study groups were composed of participants in the National Heart Lung Blood Institute (NHLBI) Family Heart Study (FHS) selected from three population-based studies: two Atherosclerosis Risk in Communities (ARIC) centers (Forsyth County, NC, and Minneapolis, MN), and the Framingham Heart Study. In multivariate analysis within ARIC Caucasians, a significant positive association was found between CHD (controls = 230, cases = 232) and the AGT TT genotype (P = 0.022; OR = 1.84, 1.09-3.10 95% CI). When we restricted the analysis to a low-risk group for CHD (controls = 70, cases = 35) an interaction between the ACE DD and AGT TT genotypes was significant (P = 0.025; OR = 5.02 1.22-20.6 95% CI). After further subsetting low-risk cases to those with a definite MI (controls = 74, cases = 16), we found that the associations with the ACE DD genotype was also significant (P = 0.013, OR = 3.94, 1.28-12.2 95% CI). Comparable tests in the Framingham sample failed to support an association of these markers with CHD. In conclusion, within selected groups the ACE D and AGT 235T alleles are statistically associated with CHD and MI, and there is a synergistic interaction between the two alleles. These results and those from previous studies together suggest that the association of these two loci is neither strong nor consistent and involves a complex interaction among risk factors and genotypes.

Angiotensinogen↗
PubMed1997

Associations of candidate loci angiotensinogen and angiotensin-converting enzyme with severe hypertension: The NHLBI Family Heart Study.

PURPOSE: In studies conducted in several different populations, the M235T substitution in the angiotensinogen (AGT) locus has been associated with hypertension. METHODS: A case-control study was initiated in an attempt to replicate this finding. Persons with hypertension, age- and sex-matched normotensive controls, and randomly sampled individuals were probands from the Family Heart Study of the National Heart, Lung, and Blood Institute. Subjects were recruited from the Atherosclerosis Risk in Communities study (ARIC) in North Carolina and Minneapolis, MN, and from the Framingham Heart Study in Massachusetts. Genotypes were determined for the M235T substitution in the AGT locus and for the insertion/deletion polymorphism in the angiotensin-converting enzyme (ACE) locus. Simple association tests as well as logistic regression analyses were performed. RESULTS: The association of AGT-T235 with hypertension was replicated in the Framingham sample (odds ratio, 1.60; 95% confidence interval, 1.11-2.30), but not in the ARIC white or black subjects. However, logistic regression analysis suggested a significant association of AGT with hypertension in both the ARIC white and Framingham samples when the effects of body mass index, triglycerides, and the presence of significant coronary heart disease were controlled. These analyses further suggested that, in the ARIC data, the relationship with the AGT locus is stronger in women than men and that there may be interaction (epistasis) between homozygotes for T235 and ACE-DD in the Framingham data. While the small sample size precluded logistic regression analysis, the frequency of the T235 allele in the black random sample was much higher than in the comparable white sample. CONCLUSIONS: These results are compatible with the presence of a genetic risk factor for hypertension in or near the angiotensinogen locus.

Angiotensinogen↗
PubMed1997

Margarine intake and subsequent coronary heart disease in men.

Margarine is a major source of trans fatty acids, the intake of which has risen since the early 20th century. Some data indicate that consumption of trans fatty acids increases the risk of coronary heart disease (CHD). In 1966-1969, 832 men from the Framingham Study, age 45-64 years and free of CHD, were administered a single 24-hour dietary recall, from which we estimated total daily margarine intake. We calculated CHD cumulative incidence rates and, using proportional hazards regression, CHD incidence rate ratios over 21 years of follow-up. Mean energy intake was 2,619 kcal; mean margarine intake was 1.8 (range 0-12) tsp per day. There were 267 incident cases of CHD. Age-adjusted CHD cumulative incidence rose over categories of margarine intake, but the increased risk was apparent only in the second half of the follow-up period. Adjusted for age and energy intake, the risk ratio for CHD for each increment of 1 teaspoon per day of margarine was 0.98 [95% confidence interval (CI) = 0.91-1.05] for the first 10 years of follow-up and 1.10 (95% CI = 1.04-1.17) for follow-up years 11-21. Adjustment for total fat intake and for cigarette smoking, glucose intolerance, left ventricular hypertrophy, body mass index, blood pressure, physical activity, and alcohol intake did not materially change the results. Butter intake did not predict CHD incidence. These data offer modest support to the hypothesis that margarine intake increases the risk of coronary heart disease.

Age Distribution↗
PubMed1996

NHLBI Family Heart Study: objectives and design.

The NHLBI Family Heart Study is a multicenter, population-based study of genetic and nongenetic determinants of coronary heart disease (CHD), atherosclerosis, and cardiovascular risk factors. In phase I, 2,000 randomly selected participants and 2,000 with family histories of CHD were identified among 14,592 middle-aged participants in epidemiologic studies. Medical histories from these individuals, their parents, and their siblings were used to calculate family risk scores that compared the number of reported and validated CHD events with the number expected based on the size, sex, and age of family members. A total of 657 families with the highest risk scores and early-onset CHD and 588 randomly sampled families had clinic examinations that included electrocardiograms, carotid artery ultrasound scans, spirometry, measurements of body size, blood pressure, lipids, lipoproteins, hemostatic factors, insulin, glucose, and routine chemistries. Additional biochemical and genetic studies are being performed on selected participants. Serum, plasma, lymphocytes, red cells, and DNA are stored for future studies, including genotyping of candidate genes and anonymous markers. Contributions of genes, shared and individual environments, and behaviors to variations in risk factors, preclinical atherosclerosis, and CHD will be estimated. Linkage studies, including the quantitative trait loci approach, are planned.

Age of Onset↗
PubMed1996

Alcohol and coronary heart disease: the evidence for a protective effect.

There is a considerable body of evidence indicating that moderate alcohol intake is associated with a reduced incidence of, and mortality from, coronary heart disease (CHD). There is also substantial evidence that problem drinking (well beyond two drinks per day) is associated with increased cardiovascular mortality. However, the frequently reported harmful effect of alcohol abuse on CHD mortality rates could be a result of mislabelling as CHD conditions such as alcohol-induced dilated cardiomyopathy, dysrhythmias, and hypertensive cardiovascular disease. The combination of protective and harmful influences of alcohol consumption results in a U-shaped mortality curve. A true protective effect of moderate intake of alcohol is likely, because of consistent findings in many large, well-conducted studies of diverse population samples and the apparent specificity of the protective effect for CHD and possibly atherosclerotic-thrombotic brain infarction. There are also biologically plausible mechanisms whereby the protection might be conferred. Alcohol has been shown convincingly to raise HDL subfractions which have been found to be protective against CHD, and it may also provide protection by an antithrombotic effect. There is a suggestion that wine, and red wine in particular, may be more protective than other alcoholic beverages. However, it is difficult to control adequately for confounding factors, since persons who prefer wine have been found to have a more advantageous lifestyle, a better cardiovascular risk profile, are better educated, and smoke less. The evidence for a protective effect of moderate alcohol intake includes population studies of alcohol and CHD mortality in 20 countries, case-control studies, prospective cohort studies, arteriographic studies, and animal experiments. Nevertheless, because there are no controlled trial data, it is possible that some other factor may be responsible for the apparent protective effect of alcohol. The inclusion of former drinkers or sick individuals in the non-drinker category, and lack of control for cigarette smoking and other risk factors, have been excluded as reasons for higher CHD rates among individuals who do not consume alcohol. No alternative explanation for the protective effect has surfaced after two decades of investigation of the alcohol-CHD relationship, yet, the penalties of heavy alcohol consumption are too large to ignore. Until we can be sure that advice that encourages the public to drink to avoid coronary heart disease does not increase abuse, we must be cautious in making general recommendations.

Alcohol Drinking↗
PubMed1996

Relation between folate status, a common mutation in methylenetetrahydrofolate reductase, and plasma homocysteine concentrations.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) synthesizes 5-methyltetrahydrofolate, the major carbon donor in remethylation of homocysteine to methionine. A common MTHFR mutation, an alanine-to-valine substitution, renders the enzyme thermolabile and may cause elevated plasma levels of the amino acid homocysteine. METHODS AND RESULTS: To assess the potential interaction between this mutation and vitamin coenzymes in homocysteine metabolism, we screened 365 individuals from the NHLBI Family Heart Study. Among individuals with lower plasma folate concentrations ( < 15.4 nmol/L), those with the homozygous mutant genotype had total fasting homocysteine levels that were 24% greater (P<.05) than individuals with the normal genotype. A difference between genotypes was not seen among individuals with folate levels > or = 15.4 nmol/L. CONCLUSIONS: Individuals with thermolabile MTHFR may have a higher folate requirement for regulation of plasma homocysteine concentrations; folate supplementation may be necessary to prevent fasting hyperhomocysteinemia in such persons.

Adult↗
PubMed1996

Risk profiles for non-communicable diseases in rural and urban schoolchildren in the Republic of Cameroon.

OBJECTIVES: In developing countries, there is evidence that the median age of the population and the life expectancy at birth are increasing as a result of decreasing fertility rates and infant mortality. The result is an aging population more prone to non-communicable diseases such as diabetes, cancer, or heart disease later in life. In addition, changing lifestyle factors such as tobacco use, physical inactivity, and high fat diets, may accelerate the emergence of such chronic diseases as major causes of death and disability in these countries, particularly in urban areas. To test the premise that urban living predisposes residents to reduced activity levels, less healthy diets, cigarette smoking, elevated blood pressure, and increased body fat early in life, we studied rural/urban differences in these risk factors among schoolchildren in the Republic of Cameroon. METHODS: One hundred and nineteen Class 7 schoolchildren (50 urban and 69 rural) were interviewed concerning diet, physical activity, smoking, and alcohol use; blood pressure and anthropometric measurements were also taken. RESULTS: Physical activity among rural children was more than twice that of urban children, and most of the activity for rural children was work-related. Rural children consumed fewer foods containing fat and more fruits and vegetables. Adjusting for age, systolic and diastolic blood pressures of urban boys were higher than those of rural boys, and among urban children there was a trend toward a larger age-adjusted mean body mass index (BMI). There were no differences in alcohol or tobacco use between urban and rural children. CONCLUSIONS: In this study, urbanization was associated with a less active lifestyle and a dietary pattern that was higher in fat and lower in fruit and vegetable intake. Since risk factors for non-communicable diseases tend to appear early in life and track into adulthood, it is important to identify those children, or groups of children, with unfavorable risk profiles and to structure health education and promotion programs to modify these trends.

Adolescent↗
PubMed1995

Preschool physical activity level and change in body fatness in young children. The Framingham Children's Study.

This study examined the effect of preschool physical activity on the change in body fatness from preschool to first grade. The Framingham Children's Study, a longitudinal study of childhood cardiovascular risk behaviors, began in 1987 with the enrollment of 106 children aged 3-5 years and their parents. The present analyses include 97 healthy children with complete data from study entry into first grade. Physical activity was assessed twice yearly for 5 days with an electronic motion sensor. The authors estimated change in the child's level of body fat from preschool to first grade by using the slopes of triceps and subscapular skinfolds and body mass index. On average, active girls (i.e., those with above-median activity levels) gained 1.0 mm in their triceps skinfolds from baseline to first grade, while inactive girls gained 1.75 mm. Active boys lost an average of 0.75 mm in their triceps, while inactive boys gained 0.25 mm. When age, television viewing, energy intake, baseline triceps, and parents' body mass indices were controlled for, inactive preschoolers were 3.8 (95% confidence interval 1.4-10.6) times as likely as active preschoolers to have an increasing triceps slope during follow up (rather than a stable or decreasing slope). This relative risk estimate was slightly higher for children with more body fat at baseline. In this study, preschool-aged children with low levels of physical activity gained substantially more subcutaneous fat than did more active children.

Body Height↗
PubMed1995

Protective effect of fruits and vegetables on development of stroke in men.

OBJECTIVE: To examine the effect of fruit and vegetable intake on risk of stroke among middle-aged men over 20 years of follow-up. DESIGN: Cohort. SETTING: The Framingham Study, a population-based longitudinal study. PARTICIPANTS: All 832 men, aged 45 through 65 years, who were free of cardiovascular disease at baseline (1966 through 1969). MEASUREMENTS AND DATA ANALYSIS: The diet of each subject was assessed at baseline by a single 24-hour recall. The estimated total number of servings per day of fruits and vegetables was the exposure variable for this analysis. Using Kaplan-Meier survival analysis, we examined age-adjusted cumulative incidence of stroke by quintile of servings per day. To adjust for multiple covariates, we used proportional hazards regression to calculate the relative risk (RR) of stroke for each increment of three servings per day. MAIN OUTCOME MEASURE: Incidence of completed strokes and transient ischemic attacks. RESULTS: At baseline, the mean (+/- SD) number of fruit and vegetable servings per day was 5.1 (+/- 2.8). During follow-up there were 97 incident strokes, including 73 completed strokes and 24 transient ischemic attacks. Age-adjusted risk of stroke decreased across increasing quintile of servings per day (log rank P for trend, .01). Age-adjusted RR for all stroke, including transient ischemic attack, was 0.78 (95% confidence interval [Cl], 0.62 to 0.98) for each increase of three servings per day. For completed stroke the RR was 0.74 (95% Cl, 0.57 to 0.96); for completed stroke of ischemic origin the RR was 0.76 (95% Cl, 0.57 to 1.02); and for completed stroke of hemorrhagic origin, 0.49 (95% Cl, 0.25 to 0.95). Adjustment for body mass index, cigarette smoking, glucose intolerance, physical activity, blood pressure, serum cholesterol, and intake of energy, ethanol, and fat did not materially change the results. CONCLUSION: Intake of fruits and vegetables may protect against development of stroke in men.

Cerebrovascular Disorders↗
PubMed1995

Should physicians intervene during childhood to prevent adult hypertension?

Hypertension in adulthood is a major health problem, and drug treatment of hypertension is expensive and has adverse side effects. By the time that treatment of hypertension begins during adulthood, considerable damage may have already been done to the arterial system, to the left ventricle, and perhaps to other organs. Thus, from several points of view, prevention would be preferable to treatment. We can consider both the high-risk approach and the population approach during childhood for the prevention of adult hypertension. In the high-risk approach, we must first identify individual children who are at high risk and then intervene among them on a one-on-one basis. Identifying the future hypertensive is difficult because of large day-to-day variability in blood pressure during childhood, poor tracking of blood pressure from childhood to adulthood, and the current lack of good gene markers for hypertension. With the population approach, we do not need to identify high-risk children, but take steps among all children that will help prevent the development of hypertension in the entire population. At the present time, our best approach for the prevention of adult hypertension seems to be the population approach. We should make the usual diet, for all children, lower in sodium and fat and higher in potassium and calcium. This is effected by increasing their intake of vegetables, fruits, and whole grains, which should become the basis of the diet, rather than high-fat meat and dairy products. Further, increasing strenuous physical activity in our children may help prevent the development of obesity. Finally, preventing the initiation of cigarette smoking and excess alcohol consumption will help in our efforts to prevent hypertension and its sequelae in the next generation of adults.

Adolescent↗
PubMed1995

Post-methionine load hyperhomocysteinemia in persons with normal fasting total plasma homocysteine: initial results from the NHLBI Family Heart Study.

Hyperhomocysteimia, either fasting or after oral methionine loading, appears to be an independent risk factor for coronary heart disease (CHD). It remains unclear whether fasting total homocysteine determination alone adequately detects the full spectrum of hyperhomocysteinemic individuals. We measured fasting and 4-h post methionine loading (0.1 g L-methionine/kg body weight) total plasma homocysteine in 274 participants in The NHLBI Family Heart Study, a population-based investigation of genetic and non-genetic determinants of CHD. Of the total number (n = 47) of hyperhomocysteinemic persons, 43% (20/47) were identified only by methionine loading, while 32% (15/47) of the total number, and 75% of those with post-methionine loading hyperhomocysteinemia only (15/20), had fasting total homocysteine concentrations below the 75th percentile (10.7 mumol/l). We conclude that fasting total plasma homocysteine determination alone fails to identify a sizable percentage (> 40%) of persons who may have clinically relevant hyperhomocysteinemia post methionine loading.

Adult↗
PubMed1995

Alcohol in the Mediterranean diet.

Alcohol consumption clearly reduces risk of cardiovascular disease (CVD) in populations throughout the world and may contribute to lower rates of CVD among residents of Mediterranean countries. In addition, overall mortality rates are generally slightly lower among moderate drinkers than among abstainers. However, several studies have linked alcohol consumption (even amounts equivalent to two drinks daily) to increased rates for certain cancers, especially breast cancer in women. A Mediterranean diet, which is high in fruit, vegetables, and grains, also typically includes one to two drinks per day. Whether one to two drinks adversely affect cancer incidence in the presence of a Mediterranean diet has not been fully explored. With the evidence currently available, we conclude that alcohol, when consumed responsibly in most populations, is an important component of the Mediterranean diet and a component of a healthy lifestyle.

Alcohol Drinking↗
PubMed1995

The tracking of nutrient intake in young children: the Framingham Children's Study.

OBJECTIVES: This study compared the nutrient intake of children at 3 through 4 years of age with that in subsequent years to determine whether nutrient intake tracked over time. METHODS: Intakes of 10 nutrients were estimated by means of multiple days of food diaries collected over a span of up to 6 years of follow-up for 95 children in the Framingham Children's Study. All diaries collected during each of three age periods (age 3 through 4, age 5 through 6, and age 7 through 8) were averaged. Nutrient density intakes at each age period were compared. RESULTS: Nutrient-specific correlations ranged from .37 to .63 between nutrient density intakes at age 3-4 and age 5-6. Correlations between intakes at age 3-4 and age 7-8 ranged from .35 to .62. Consistency of classification was strong; 35.7% to 57.1% of children in the highest quintile of intake at age 3-4 remained in that quintile at age 5-6, and 57.1% to 85.7% remained in the top two quintiles. At age 7-8, 40.0% to 66.7% of those with the highest intake at baseline were still in the top quintile, and 60.0% to 93.3% remained in the top two quintiles. Results were similar in the lowest quintile of intake. Extreme misclassification was rare. CONCLUSIONS: This study suggests that tracking of nutrient intake begins as young as 3-4 years of age.

Age Factors↗
PubMed1994

Estimates of blood pressure variability in adolescents using an automatic blood pressure measuring device.

Knowledge of BP variability is important for BP screening and for the design of studies with BP as an outcome. We calculated estimates of the between-visit and within-visit variances from data obtained using an automated BP.device (Dinamap) in 776 students, aged 13-17 years, in the Exeter-Andover Project. Each subject had his or her BP measured three times per visit at up to 24 weekly visits. We compared these estimates of variance with those published for adolescents using a standard mercury sphygmomanometer. For subjects measured using the Dinamap, the between-visit variance was greater for SBP and the within-visit variance for both pressures was almost three times greater than for subjects measured with the standard instrument.

Adolescent↗
PubMed1993

Lipid and lipoprotein distributions in children by ethnic group, gender, and geographic location--preliminary findings of the Child and Adolescent Trial for Cardiovascular Health (CATCH).

BACKGROUND: The Child and Adolescent Trial for Cardiovascular Health is a school-based study designed to test the effectiveness of dietary, physical activity, and educational interventions for reducing cardiovascular disease risk and teaching healthful behaviors to children. METHODS: As part of a pilot phase in 1989, lipid, lipoprotein, and anthropometric measures were taken in black (n = 90), Hispanic (n = 68), and white (n = 265) 8- to 10-year-old schoolchildren in California, Louisiana, Minnesota, and Texas. RESULTS: There were no significant differences in mean lipoprotein cholesterol values between fasting and nonfasting children. Therefore data from fasting and nonfasting children were pooled. Males and females within the same ethnic groups had similar mean levels of total cholesterol, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol. However, levels of high-density lipoprotein cholesterol were higher among white and black males than among females from the same ethnic groups. Black males had higher total cholesterol than white males and higher high-density lipoprotein cholesterol than white males and Hispanic males. Similarly, black females had higher high-density lipoprotein cholesterol than white and Hispanic females. In all children combined high-density lipoprotein cholesterol was inversely correlated and low-density lipoprotein cholesterol was positively correlated with subscapular and tricep skinfold thickness, weight, and body mass index. There were significant differences in mean lipoprotein cholesterol levels between geographic sites. Total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were highest in children from California followed by children from Texas, Minnesota, and Louisiana. CONCLUSION: Our results suggest that body fatness total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol differ in children by gender, ethnicity, and geographic location.

Analysis of Variance↗
PubMed1993

Childhood prevention of essential hypertension.

Childhood prevention of essential hypertension requires knowledge of alterable determinants of blood pressure in children; these include obesity and sodium intake and perhaps physical activity and intake of potassium and calcium. Altering these determinants may involve two general preventive strategies. The first is a population strategy, which attempts to lower blood pressure (or keep it from rising) among all children. Population strategies may require educating children to active participants in changing their behaviors (active approach) or may merely change their environment (passive approach). The second general strategy aims to focus on children at high risk of developing hypertension as adults. To determine the usefulness of this high-risk strategy, more information is needed about prediction of adult blood pressure from childhood values and about the efficacy of interventions to control blood pressure levels in high-risk children.

Child↗