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Biomedical subjects

T Byers

Publications and source records attributed to T Byers.

At least 91 records · Page 5Linked to original sources
PubMed1993

The relation of atherosclerotic lesions to antemortem and postmortem lipid levels: the Bogalusa Heart Study.

Although postmortem lipid levels have been used as surrogates for levels during life, it is uncertain whether atherosclerotic lesions are related similarly to antemortem and postmortem lipid values. In a sample of 23 children and young adults who had been examined for cardiovascular disease risk factors and subsequently died from violent causes, we examined the relation of (a) postmortem lipid levels to values obtained 1 to 14 years earlier, and (b) atherosclerotic lesions to antemortem and postmortem lipid levels. Postmortem levels of triglycerides and very-low-density lipoprotein cholesterol (VLDLC) were higher than levels during life, but postmortem levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDLC) and high-density lipoprotein cholesterol (HDLC) were related to antemortem levels (rs > 0.40). After excluding eight persons who likely received large volumes of intravenous fluids before death, the within-person variability between antemortem and postmortem levels of LDLC and HDLC was similar to the antemortem variability. Furthermore, the relation of atherosclerotic lesions to antemortem and postmortem lipid levels differed only slightly for TC, LDLC and HDLC. In contrast, lesions in the coronary arteries showed the strongest association with antemortem VLDLC levels, but were not associated with postmortem VLDLC levels. Despite the very small number of subjects, our results suggest that if intravenous fluids are not administered before death, postmortem levels of TC, LDLC and HDLC are fairly representative of levels during life. Postmortem levels of VLDLC or triglycerides, however, should not be used as surrogates for antemortem levels.

Adolescent↗
PubMed1993

Defining the year 2000 fruit and vegetable goal.

Various nutrition guidelines recommend increased consumption of fruits and vegetables (F+V); a Year 2000 goal targets five or more daily servings of F+V. Decisions are needed regarding how to define F+V to facilitate measurement of goal achievement. Four alternative definitions (narrow and broad, each with and without legumes) were developed and applied to food frequencies from 133 children and 211 parents. Results varied by definition. Mean intake met the goal of five or more daily servings regardless of definition and exceeded it for both broad definitions by children and both broad definitions and the narrow definition with legumes for adults. Median intakes met the goal for all definitions except for children with the narrow definition without legumes, and exceeded it for children with both broad definitions and for adults with the broad definition with legumes. These differences by definition indicate that a clear definition of F+V is needed.

Adult↗
PubMed1993

Evaluation of a brief telephone questionnaire to estimate fruit and vegetable consumption in diverse study populations.

We evaluated the use of a six-item telephone questionnaire to estimate fruit and vegetable intakes in five diverse populations. Researchers administered the telephone questionnaire to persons who had previously undergone more extensive dietary assessment. The study population included 553 middle-aged and older adults in Beaver Dam, WI; 252 middle-aged and older women throughout Wisconsin; 150 parents of school children in Augusta, GA; 73 low-income, Hispanic mothers in Chicago, IL; and 51 older adults in Arizona. Spearman correlation coefficients between total fruit and vegetable intakes measured by the brief telephone survey and by more extensive food frequency questionnaires were 0.47 (Augusta), 0.48 (Arizona), 0.56 (Wisconsin), and 0.57 (Beaver Dam). Correlations between intakes measured by the brief telephone survey and by multiple diet records or recalls were 0.29 (Arizona), 0.46 (Chicago), and 0.54 (Beaver Dam). With the exception of Arizona, mean daily fruit and vegetable intakes measured by the telephone survey were similar to intakes estimated by multiple diet records or recalls and lower than those estimated by extensive food frequency questionnaires. Although caution may be needed in interpreting dietary reports from some ethnic subgroups, this brief telephone questionnaire may be useful for surveillance of fruit and vegetable intake in the United States.

Adolescent↗
PubMed1993

Vitamin E supplements and coronary heart disease.

Although two new epidemiologic studies on the association between vitamin E and heart disease do not resolve important issues related to dose-response, mechanisms of action, or specificity, they do provide important evidence that supports the development of new strategies for preventing heart disease.

Adult↗
PubMed1993

Vitamin and mineral supplement use and mortality in a US cohort.

OBJECTIVES: Vitamin and mineral supplementation is a common practice in the United States, yet little is known about the long-term health effects of regular supplement use. METHODS: To examine the relationship between reported use of supplements and mortality, we analyzed data from US adults 25 to 74 years of age who were examined in the First National Health and Nutrition Examination Survey (1971 to 1975), with vital status determined through 1987. RESULTS: At baseline, 22.5% of the cohort reported using supplements regularly and 10.0% reported irregular use. The risk of mortality for regular supplement users was similar to that for nonusers. No consistent mortality benefits or risks of supplement use were found across a number of population subgroups. The risk for those who reported supplement use at both the baseline and a follow-up interview approximately 10 years later was similar to the risk for those who reported not using supplements at either interview. CONCLUSIONS: We found no evidence of increased longevity among vitamin and mineral supplement users in the United States. Considering the wide use of supplements in the general population, the cost-effectiveness and the safety of supplement use need to be better defined.

Adult↗
PubMed1993

The accuracy of parental reports of their children's intake of fruits and vegetables: validation of a food frequency questionnaire with serum levels of carotenoids and vitamins C, A, and E.

It has been recommended that U.S. children increase their dietary intake of fruits and vegetables. Measuring diets of children to support and evaluate nutritional interventions can be a difficult task, however. We administered to 97 parents of children age 6-10 years a food frequency questionnaire on their children's usual dietary intake over the previous 3 months. We then compared these reports by parents of their children's intakes of fruits and vegetables, and the derived estimates of intake of carotenoids and vitamins C, A, and E, with the children's serum levels of carotenoids and vitamins C, A, and E. The dietary reports of intakes of 35 fruits and vegetables showed Spearman rank-order correlations of 0.30 with serum carotenoids and 0.34 with serum vitamin C. Children in the highest quartile for intake of fruits and vegetables according to their parents' food frequency reports had 35% higher carotene levels and 31% higher vitamin C levels in their serum than did children in the lowest quartile for intake of fruits and vegetables. We conclude that parental reports of young children's diets using food frequency methods are accurate enough to be useful in nutritional screening and dietary surveillance of fruit and vegetable intake.

Ascorbic Acid↗
PubMed1993

Recreational physical activity and ten-year weight change in a US national cohort.

Clinical research has established that increases in physical activity cause weight loss among the obese, but less is known about the influence of physical activity on longer-term weight change in the general population. Data from the NHANES-I Epidemiologic Follow-up Study (1971-1975 to 1982-1984) were used to examine the relationship between self-reported recreational physical activity level (low, medium, high) and measured weight change after ten years among 3515 men and 5810 women aged 25-74 years. Cross-sectional analyses at both the baseline and follow-up surveys revealed that recreational physical activity was inversely related to body weight. Low recreational physical activity reported at the follow-up survey was strongly related to major weight gain (> 13 kg) that had occurred during the preceding ten years. The estimated relative risk of major weight gain for those in the low activity level at the follow-up survey compared to those in the high activity level was 3.1 (95% Cl = 1.6-6.0) in men and 3.8 (2.3-6.5) in women. In addition, the relative risk for persons whose activity level was low at both the baseline and follow-up surveys was 2.3 (0.9-5.8) in men and 7.1 (2.2-23.3) in women. However, no relationship was found between baseline physical activity level and subsequent weight gain among either men or women. The lack of a relationship may be due to mis-specification of physical activity because of changes in activity over time. These findings suggest that low physical activity may be both a cause and a consequence of weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Risk factors for fatal colon cancer in a large prospective study.

BACKGROUND: Diet, physical activity, obesity, aspirin use, and family history may all modify the risk of colon cancer, but few epidemiologic studies are large enough to examine these factors simultaneously. PURPOSE: We prospectively assessed the relationship of diet and other factors to risk of fatal colon cancer. METHODS: Using data from Cancer Prevention Study II--an ongoing prospective mortality study--we studied 764,343 adults who, in 1982, completed a questionnaire on diet and other risk factors and did not report cancer or other major illness. We assessed mortality through August 1988 and identified 1150 deaths from colon cancer (611 men and 539 women). Multivariate analyses were used to compare these case patients with 5746 matched control subjects drawn from the cohort. RESULTS: Risk of fatal colon cancer decreased with more frequent consumption of vegetables and high-fiber grains (P for trend = .031 in men and .0012 in women). The relative risk (RR) for the highest versus lowest quintile of vegetable intake was 0.76 in men (95% confidence interval [CI] = 0.57-1.02) and 0.62 in women (95% CI = 0.45-0.86). Dietary consumption of vegetables and grains and regular use of aspirin were the only factors having an independent and statistically significant association with fatal colon cancer. Participants who consumed the least vegetables and grains and no aspirin had a higher risk compared with those who consumed the most vegetables and used aspirin 16 or more times per month. For men in the former category, the RR was 2.4 (95% CI = 1.1-5.3); for women, it was 2.9 (95% CI = 1.3-6.7). Weaker associations were seen for physical inactivity, obesity, total dietary fat, and family history. No associations were seen with consumption of red meat or total or saturated fat in either sex, but this finding must be interpreted cautiously. CONCLUSIONS: These findings support recommendations that increased consumption of vegetables and grains may reduce the risk of fatal colon cancer. Regular use of low doses of aspirin may prove to be an important supplemental measure.

Adult↗
PubMed1992

Weight loss and mortality in a national cohort of adults, 1971-1987.

Although obesity is a risk factor for mortality, evidence that weight loss improves survival is limited. The relation between self-reported previous maximum weight, weight loss, and subsequent mortality was examined in 2,140 men and 2,550 women aged 45-74 years who participated in the First National Health and Nutrition Examination Survey (1971-1975) and survived the next 5 years. Vital status was determined through 1987. Among men and women whose maximum body mass index (weight (kg)/height (m)2) was between 26 and 29, risk of death increased with increasing weight loss, after adjustment for age, race, smoking, parity, preexisting illnesses, and maximum body mass index. Subjects who lost 15% or more of their maximum weight had over twice the mortality risk of those who lost less than 5%. At maximum body mass indices of 29 or higher, mortality risk increased with the amount of weight lost in women, but weight loss of 5% to < 15% appeared to lessen mortality risk in men. Generalization from these results is limited by the older age range of the sample and the inability to adequately distinguish voluntary from involuntary weight loss in this study. However, these findings suggest that prevention of severe overweight may be more generally effective than weight loss in reducing obesity-related mortality in the US population.

Aged↗
PubMed1992

Estimates of costs and effects of screening for colorectal cancer in the United States.

BACKGROUND: In many ways, colorectal cancer might be an excellent candidate for mass screening because of the following: (1) it is the second leading cause of cancer mortality in the United States; (2) it develops slowly from a precursor lesion; and (3) methods of early detection are available. Barriers to screening include unproven efficacy of the procedure and high costs. METHODS: Cost analyses are derived from two mathematic models that estimate screening costs and effects based on expert opinion and data from uncontrolled screening studies. RESULTS: One screening option that follows the guidelines of the American Cancer Society and the National Cancer Institute (annual testing for occult fecal blood and sigmoidoscopy every 5 years) could result in a 40% decrease in colon cancer mortality for American adults between the ages of 50 and 75 years if they comply with screening. This model, developed by David Eddy, projects an average of 44 days of extra life per person screened, at a net cost of $57 per day of life gained. Using assumptions much less favorable to screening, the Office of Technology Assessment modeled this same screening strategy for those aged 65 years and older. This model predicted a similar benefit of extra life per person at a cost of $118 per day of life gained. This doubling of the predicted cost was caused by the inclusion of subsequent colonoscopic surveillance costs for those found to have polyps. Direct costs of screening annually for fecal occult blood and every 5 years by sigmoidoscopy would cost an average of approximately $48 per person per year for screening and follow-up testing of all positive results. Fecal occult blood testing alone, although less effective, costs only $20 per person per year, including follow-up testing of all positive findings. CONCLUSIONS: The results from randomized trials of fecal occult blood screening will be known in the next 5 years, but trials of screening with sigmoidoscopy will not be complete for 10-15 years. Because mass screening programs will be difficult to fund without better data on their efficacy, colorectal cancer screening will continue to be a matter of individual decision making in the clinical setting for years to come. Clearer presentations of costs and benefits that can be understood by both patients and physicians are needed.

Adult↗
PubMed1992

The relation of prothrombin times to coronary heart disease risk factors among men aged 31-45 years.

Although levels of coagulation factor VII and fibrinogen are predictive of cardiovascular disease, relatively little data describe hemostatic characteristics in healthy populations. The cross-sectional associations between the prothrombin time, a measure of the activity of the extrinsic and common pathways of coagulation, and traits associated with the risk of cardiovascular disease were therefore examined among 3,604 white and 514 black, male, US Army veterans aged 31-45 years. The prothrombin time measurements, performed in 1985 and 1986, were precise, with an intraclass correlation of 0.98 (202 pairs). Overall, the mean prothrombin time was 12.4 seconds (standard deviation, 0.4 seconds), and 11 percent of the men had a value of less than 12 seconds. Many of the observed associations with the prothrombin time paralleled those that have been reported with clotting factor VII and fibrinogen. The mean prothrombin time was 0.15 seconds shorter among whites than among blacks and was 0.2 seconds shorter among current cigarette smokers than among men who had never smoked. Inverse associations were also seen with relative weight and with levels of total cholesterol and triglycerides (r = -0.09 to -0.16). All associations were statistically significant at the 0.01 level, and the examined characteristics could jointly account for about 12 percent of the variability in prothrombin times. Additional data on characteristics related to coagulation may help elucidate the natural history of cardiovascular disease and aid in the design of clinical trials.

Adult↗
PubMed1992

Congenital defects and electric bed heating in New York State: a register-based case-control study.

Exposure to 60-cycle electromagnetic fields has been hypothesized to be a cause of childhood cancer and congenital defects. Because electric bed heaters are a major source of variation in electromagnetic field exposure in the population, the authors conducted a case-control study in 1988-1989 to examine the relations between congenital defects and the use of electric blankets and heated waterbeds. Cases were identified by the New York State Congenital Malformations Registry as babies with cleft palate (n = 121), cleft lip with or without cleft palate (n = 197), born in 1983-1984, and anencephalus and spina bifida (n = 224), born in 1983-1986, all to upstate New York residents. Controls were selected at random from birth registrations individually matched to cases by maternal race, age, home county, month of last menses, and child's sex. Information on periconceptional electric blanket and heated waterbed use as well as known and suspected risk factors for defects was obtained from questionnaires mailed to the mothers. Matched odds ratio estimates and 95% confidence intervals (CIs) for electric blanket use relative to nonuse were 0.8 (95% CI 0.3-2.1) for cleft palate, 0.7 (95% CI 0.3-1.3) for cleft lip, and 0.9 (95% CI 0.5-1.6) for neural tube defects. The respective odds ratios for heated waterbed use were nearly identical to these. Adjustment for potential confounding factors (maternal education, vitamin use, smoking) and stratification by season of conception and bed heat control setting had no meaningful effect on odds ratios. These results suggest that 60-cycle fields do not cause neural tube and oral cleft defects.

Adult↗
PubMed1992

Serum cholesterol levels in a multiracial sample of 7,439 preschool children from Arizona.

BACKGROUND: The distribution and correlates of serum levels of total cholesterol were studied in cross-sectional analyses of 7,439 1 to 4 year olds examined through the Arizona Department of Health Services. RESULTS: Mean cholesterol levels increased with age, and levels among 2 year olds approached those seen in adolescents. Racial and ethnic differences in cholesterol levels were observed: mean (age-adjusted) levels were 147 mg/dl among American Indians (n = 622), 153 mg/dl among Hispanics (n = 3165), 154 mg/dl among non-Hispanic whites (n = 3448), and 163 mg/dl among blacks (n = 204). Cholesterol levels were not associated either with obesity, as assessed by relative weight or the Quetelet index, or with breast-feeding during infancy. Very overweight (greater than or equal to 20 kg/m2) 3 and 4 year olds, however, tended to have higher mean levels of cholesterol than did other children. The proportion of children with borderline (170 to 199 mg/dl) or high (greater than or equal to 200 mg/dl) levels of cholesterol varied by race/ethnicity: borderline (high) levels were seen among 14% (3%) of American Indians and 29% (11%) of blacks. The proportions of white and Hispanic children having cholesterol levels between 170 and 199 mg/dl or greater than or equal to 200 mg/dl were midway between those seen among American Indians and blacks. CONCLUSION: Additional information on the interrelationships of lipids and lipoproteins may aid in the identification of children who will be at increased risk for cardiovascular disease in adulthood.

Age Factors↗
PubMed1992

The diet of Alaska Native adults: 1987-1988.

Although in the past, rates of heart disease, cancer, and diabetes were lower in Alaska Natives than in US whites, these diseases are now increasing. The rate of iron-deficiency anemia for Alaska Natives continues to be higher than that in the general population. To understand the role of diet in these chronic diseases, seasonal dietary intakes of 351 Alaska Native adults from 11 communities were assessed during 1987-1988. Alaska Natives consumed more energy (19%), protein (39%), fat (21%), carbohydrate (13%), iron (25%), vitamin A (53%), and vitamin C (31%), but less calcium (19%) than did the general US adult population [National Health and Nutrition Examination Survey II (NHANES II)]; Alaska Natives consumed six times more fish but less fruits and vegetables. Results suggest that energy and protein intakes decreased in the last 30 y but the proportion of energy from fat (37%) remained unchanged. High fish consumption and large seasonal dietary variations persisted, which may protect against chronic diseases. However, excess energy and fat and low calcium, fruit, and vegetable intakes may be contributing to recent increases in chronic diseases. Dietary guidelines are proposed.

Adult↗
PubMed1992

Iron nutrition does not account for the hemoglobin differences between blacks and whites.

Many researchers have reported lower hemoglobin concentrations in blacks than in whites, but the reason for this difference is unknown. Data for 2515 persons (in 3-12 y and 18-45 y age groups) from the Second National Health and Nutrition Examination Survey (NHANES II) were evaluated to investigate the roles of iron intake and biochemical iron status indicators in explaining black and white differences in hemoglobin concentration. Dietary iron intake was estimated from one 24-h food recall, and hemoglobin, serum ferritin, transferrin saturation and erythrocyte protoporphyrin were measured by standard laboratory methods. Hemoglobin levels were substantially lower in black children (120.3 g/L) than in white children (126.8 g/L). Hemoglobin concentrations were also lower in black women (128.4 g/L) than in white women (133.9 g/L), and in black men (144.8 g/L) than in white men (153.2 g/L). Blacks had lower hemoglobin concentration than whites at most levels of dietary iron intake, serum ferritin, transferrin saturation and erythrocyte protoporphyrin. Despite their lower hemoglobin levels, blacks had higher serum ferritin levels than whites. These results suggest that the difference in hemoglobin concentrations between blacks and whites in the United States is the result of factors other than iron intake and iron status. More specific investigations of both the genetic and environmental determinants of iron utilization in blacks are needed.

Adult↗
PubMed1992

Assessing consumption of high-fat foods: the effect of grouping foods into single questions.

Questionnaires on the frequency of consumption of foods are commonly used to measure dietary intake in epidemiologic research. To reduce the burden on respondents, questionnaires are often shortened by combining inquiries on similar foods into a single question. The effect of this practice on the reporting of dietary intake has never been investigated, however. To address this issue, we used two food frequency questionnaires in a telephone survey designed to rank adult residents of Alabama by their intake of dietary fat. One questionnaire included 29 questions about separate high-fat foods, whereas the other grouped these same foods into 14 questions. Compared with the 443 respondents interviewed using the 29-item separated-foods questionnaire, the 465 respondents responding to the 14-item grouped-foods questionnaire reported lower average intakes of the foods. In addition, a substantially higher percentage of respondents to the grouped-foods questionnaire reported never consuming the foods.

Adolescent↗