Biomedical subjects

E W Gunter

Publications and source records attributed to E W Gunter.

At least 55 records · Page 3Linked to original sources

PubMed1996

Serum carotenoid concentrations and their reproducibility in children in Belize.

Suggestions that carotenoid-containing foods are beneficial in maintaining health have led to several studies of circulating carotenoid concentrations of adults. Because few data are available for children, we report serum carotenoid concentrations of 493 children in Belize. Carotenoid concentrations were determined as part of a survey of vitamin A status of children, most between 65 and 89 mo of age. Reproducibility was tested by collecting a second blood sample 2 wk after the first collection from a subset of children (n = 23) who consumed their habitual diet with no treatment during the interim. Predominant serum carotenoids were lutein/zeaxanthin and beta-carotene, which accounted for 26% and 24% of median total carotenoids, respectively. The three provitamin A carotenoids, alpha- and beta-carotene and beta-cryptoxanthin, constituted 51% of median total carotenoid concentrations. Partial correlations of each carotenoid with fasting retinol concentration indicated that beta-carotene had the highest correlation. Concordance correlation coefficients (rc) for fasting carotenoid concentrations determined 2 wk apart were > or = 0.89 for lycopene, beta-cryptoxanthin, and alpha- and beta-carotene. The rc for lutein/zeaxanthin and total carotenoids was lower, 0.59 and 0.68, respectively, because of higher lutein/zeaxanthin concentrations at the second sampling than at the first. The reproducibility of the concentrations suggests both that individuals have characteristic profiles and that serum carotenoid concentrations can be measured randomly over > or = 2 wk without significant bias.

Belize↗

PubMed1996

Colorectal cancer and folate status: a nested case-control study among male smokers.

Evidence is accumulating that folate, a B vitamin found in green leafy vegetables, may affect the development of neoplasia. We examined the relationship between folate status and colorectal cancer in a case-control study nested within the Alpha-Tocopherol Beta-Carotene Study cohort of male smokers 50-69 years old. Serum folate was measured in 144 incident cases (91 colon, 53 rectum) and 276 controls matched to cases on baseline age, clinic, and time of blood collection. Baseline dietary folate was available from a food-use questionnaire for 386 of these men (92%). Conditional logistic regression modeling was used. No statistically significant association was observed between serum folate and colon or rectal cancer. Although a 2-fold increase in rectal cancer risk was suggested for men with serum folate > 2.9 ng/ml and those in the highest quartile of energy-adjusted folate intake, there was no evidence of a monotonic dose-response, and all confidence intervals included unity. For dietary folate and colon cancer, odds ratios of 0.40 [95% confidence interval (CI), 0.16-0.96], 0.34 (95% CI, 0.13-0.88), and 0.51 (95% CI, 0.20-1.31) were obtained for the second through fourth quartiles of energy-adjusted folate intake, respectively, compared to the first (P for trend = 0.15). Furthermore, men with a high-alcohol, low-folate, low-protein diet were at higher risk for colon cancer than men who consumed a low-alcohol, high-folate, high-protein diet (OR, 4.79; 95% CI, 1.36-16.93). This study suggests a possible association between low folate intake and increased risk of colon cancer (but not rectal cancer) and highlights the need for further studies that measure dietary folate and methionine, along with biochemical measures of folate (i.e., erythrocyte and serum), homocysteine, and vitamin B12.

Aged↗

PubMed1996

Results of an international round robin for serum and whole-blood folate.

Because of the increasing significance of folate nutriture to public health, a "round robin" interlaboratory comparison study was conducted to assess differences among methods. Twenty research laboratories participated in a 3-day analysis of six serum and six whole-blood pools. Overall means, SDs, and CVs derived from these results were compared within and across method types. Results reported for serum and whole-blood folate demonstrated overall CVs of 27.6% and 35.7%, respectively, across pools and two- to ninefold differences in concentrations between methods, with the greatest variation occurring at critical low folate concentrations. Although results for serum pools were less variable than those for whole-blood pools, substantial intermethod variation still occurred. The overall results underscore the urgent need for developing and validating reference methods for serum and whole-blood folate and for properly characterized reference materials. For evaluating study or clinical data, method-specific reference ranges (established with clinical confirmation of values for truly folate-deficient individuals) must be used.

Adult↗

PubMed1995

Relation of serum uric acid to mortality and ischemic heart disease. The NHANES I Epidemiologic Follow-up Study.

Although hyperuricemia is frequently found among persons with ischemic heart disease, its importance as a risk factor remains uncertain. The authors examined this relation among 5,421 persons in the First National Health and Nutrition Examination Survey (NHANES I) Epidemiologic Follow-up Study; baseline data were collected in 1971-1975 and follow-up was through 1987. No associations were seen among men, but, among women, the serum uric acid level was predictive of mortality from all causes and from ischemic heart disease. These associations persisted even after excluding the first 10 years of follow-up and were independent of use of antihypertensive agents and diuretics, diastolic blood pressure, overweight, and other characteristics. A dose-response relation was evident for mortality from ischemic heart disease: each 1-mg/dl change in uric acid (about two thirds of the standard deviation) among women increased the rate by 1.48 (95% confidence interval 1.3-1.7). Furthermore, as compared with women who had a uric acid level < 4 mg/dl, those with a level > or = 7 mg/dl had a 4.8-fold (95% confidence interval 1.9-12) higher rate of ischemic heart disease mortality. In contrast, the uric acid level showed a weaker relation with disease incidence among women, with a rate ratio of 1.14 for each 1-mg/dl change. Although the biologic mechanism is unclear, further investigation into the possible role of uric acid in the development of ischemic heart disease is needed.

Adult↗

PubMed1995

Serum zinc and serum lipid profiles in 778 adults.

There has been increasing use of high-dosage zinc supplementation in the population, in particular as a potential treatment for age-related macular degeneration. We examined the relationship between fasting serum zinc and serum lipid levels in 778 adults, aged 22 to 80 years, who were control subjects in a multicenter, clinic-based case-control study. The samples were taken during 1987 to 1990, a time when vitamin/mineral supplementation was becoming increasingly common. We found that higher serum zinc levels, most notably those above the highest quintile, were associated with higher levels of total serum cholesterol, low-density-lipoprotein cholesterol, and triglycerides. No significant trend was noted for high-density-lipoprotein cholesterol. Previous studies demonstrated that high-dosage zinc supplements raise serum zinc levels. The possibility that use of such supplements can adversely affect serum lipid profiles suggests that chronic ingestion of such supplements should not be done without adequate medical supervision.

Adult↗

PubMed1995

Diabetes mellitus in Egypt: risk factors and prevalence.

Major sociodemographic changes have occurred in Egypt to promote the development of noncommunicable diseases. We have performed a cross-sectional, population-based survey of persons > or = 20 years of age in Cairo and surrounding rural villages to describe the prevalence of diabetes risk factors, diagnosed diabetes, previously undiagnosed diabetes, and impaired glucose tolerance by age, sex, rural and urban residence, and socioeconomic status (SES). In the survey, we identified 6052 eligible households: 76% of household respondents completed a household examination and 72% of selected household respondents subsequently completed a medical examination. Exercise was assessed by questionnaire; adiposity by measurement of height, weight, and girths; and diabetes by history and 2-h 75 g oral glucose tolerance test. In rural areas, 52% of persons > or = 20 years of age were sedentary, 16% were obese, and 4.9% had diabetes. In lower SES urban areas, 73% were sedentary, 37% were obese, and 13.5% had diabetes. In higher SES urban areas, 89% were sedentary, 49% were obese, and 20% had diabetes. The combined prevalence of diagnosed and undiagnosed diabetes in the Egyptian population > or = 20 years of age was estimated to be 9.3%. Approximately half the diabetes was diagnosed and the other half was previously undiagnosed. The prevalence of diabetes in Egypt is high, and the gradient in risk factors and disease from rural to urban areas and in urban areas from lower to higher SES suggest that diabetes is a major, emerging clinical and public health problem in Egypt.

Adult↗

PubMed1995

Methods to assess iron status in various NHANES surveys.

This paper summarizes iron status measurements included in the three cross-sectional National Health and Nutrition Examination Surveys (NHANES) completed to date, as well as a special study of Hispanics, known as the Hispanic Health and Nutrition Examination Survey (HHANES). Approaches for defining iron status in the population based on these measurements are also described as well as issues in comparing iron status data between surveys, using NHANES II and III data as an example.

Age Factors↗

PubMed1995

Screening for diabetes mellitus in adults. The utility of random capillary blood glucose measurements.

OBJECTIVE: Because half of the people with non-insulin-dependent diabetes mellitus (NIDDM) are undiagnosed and because near-normal glycemic control can prevent diabetic complications, we evaluated the use of field-based random capillary blood glucose measurement as a screening test for NIDDM. RESEARCH DESIGN AND METHODS: A cross-sectional sample of 828 Egyptians > or = 20 years of age underwent both a random capillary blood glucose measurement performed with a portable reflectance meter in the field and an oral glucose tolerance test in the laboratory. The sensitivity and specificity of random capillary blood glucose measurements in predicting the presence of NIDDM were evaluated. RESULTS: Multivariate analyses showed that the screening test performed better when subjects had eaten shortly before the test (area under receiver operating characteristic curve, 0.87 for a 1-h postprandial period compared with 0.69 for an 8-h postprandial period) and that the optimal capillary blood glucose cutoff points to define a positive test increased with age. For a postprandial period of 1 h, cutoff points of 115 mg/dl for individuals 30 years of age and 140 mg/dl for those 75 years of age yielded similar performance characteristics (sensitivity 82% and specificity 78% for those 30 years old; sensitivity 81% and specificity 80% for those 75 years old). CONCLUSIONS: Adjusting random capillary blood glucose measurements for the postprandial period and using age-specific cutoff point values can improve performance of the screening test.

Adult↗

PubMed1994

Blood lead levels in the US population. Phase 1 of the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1991)

OBJECTIVE: To determine mean blood lead levels and their sociodemographic correlates in the US population. DESIGN: Nationally representative cross-sectional health examination survey that included measurements of venous blood lead. PARTICIPANTS: A total of 13,201 persons aged 1 year and older examined during phase 1 of the third National Health and Nutrition Examination Survey (1988 to 1991). RESULTS: The overall mean blood lead level for the US population was 0.14 mumol/L (2.8 micrograms/dL). Blood lead levels were consistently higher for younger children than for older children, for older adults than for younger adults, for males than for females, for blacks than for whites, and for central-city residents than for non-central-city residents. Other correlates of higher blood lead levels included low income, low educational attainment, and residence in the Northeast region of the United States. National estimates for children 1 to 5 years of age indicate that 8.9%, or approximately 1.7 million children, have blood lead levels 0.48 mumol/L (10 micrograms/dL) or greater. These levels are high enough to be of health concern under 1991 Centers for Disease Control and Prevention guidelines. CONCLUSIONS: The low overall mean blood lead levels demonstrate a major public health success in primary prevention efforts. However, exposure to lead at levels that may adversely affect the health of children remains a problem especially for those who are minority, urban, and from low-income families. Strategies to identify the most vulnerable risk groups are necessary to further reduce lead exposure in the United States.

Adolescent↗

PubMed1994

The decline in blood lead levels in the United States. The National Health and Nutrition Examination Surveys (NHANES)

OBJECTIVE: To describe trends in blood lead levels for the US population and selected population subgroups during the time period between 1976 and 1991. DESIGN: Two nationally representative cross-sectional surveys and one cross-sectional survey representing Mexican Americans in the southwestern United States. SETTING/PARTICIPANTS: Participants in two national surveys that included blood lead measurements: the second National Health and Nutrition Examination Survey, 1976 to 1980 (n = 9832), and phase 1 of the third National Health and Nutrition Examination Survey, 1988 to 1991 (n = 12,119). Also, Mexican Americans participating in the Hispanic Health and Nutrition Examination Survey, 1982 to 1984 (n = 5682). RESULTS: The mean blood lead level of persons aged 1 to 74 years dropped 78%, from 0.62 to 0.14 mumol/L (12.8 to 2.8 micrograms/dL). Mean blood lead levels of children aged 1 to 5 years declined 77% (0.66 to 0.15 mumol/L [13.7 to 3.2 micrograms/dL]) for non-Hispanic white children and 72% (0.97 to 0.27 mumol/L [20.2 to 5.6 micrograms/dL]) for non-Hispanic black children. The prevalence of blood lead levels 0.48 mumol/L (10 micrograms/dL) or greater for children aged 1 to 5 years declined from 85.0% to 5.5% for non-Hispanic white children and from 97.7% to 20.6% for non-Hispanic black children. Similar declines were found in population subgroups defined by age, sex, race/ethnicity, income level, and urban status. Mexican Americans also showed similar declines in blood lead levels of a slightly smaller magnitude over a shorter time. CONCLUSIONS: The results demonstrate a substantial decline in blood lead levels of the entire US population and within selected subgroups of the population. The major cause of the observed decline in blood lead levels is most likely the removal of 99.8% of lead from gasoline and the removal of lead from soldered cans. Although these data indicate major progress in reducing lead exposure, they also show that the same sociodemographic factors continue to be associated with higher blood lead levels, including younger age, male sex, non-Hispanic black race/ethnicity, and low income level. Future efforts to remove other lead sources (eg, paint, dust, and soil) are needed but will be more difficult than removing lead from gasoline and soldered cans.

Adolescent↗

PubMed1994

Dietary glutathione intake in humans and the relationship between intake and plasma total glutathione level.

Glutathione may function as an anticarcinogen by acting as an antioxidant or by binding with cellular mutagens. Orally administered glutathione increases plasma glutathione levels, and plasma glutathione is also synthesized in the liver. To investigate the associations between glutathione intake and plasma glutathione level, we compared dietary intake estimates from food frequency questionnaire data and measured concentrations of plasma total glutathione and other serum antioxidants in 69 white men and women. Daily glutathione intake ranged from 13.0 to 109.9 mg (mean 34.8 mg). Fruits and vegetables were found to contribute over 50% of usual dietary glutathione intake, whereas meats contributed less than 25%. Small negative correlations were observed between dietary and plasma glutathione and, although they were usually not statistically significant, they were generally consistent by different time periods of dietary intake assessment. Adjustment for sex, age, caloric intake, and dietary intake of the sulfur-containing amino acids methionine and cystine did not alter the observed associations. The correlations appeared to be modified, however, by serum vitamin C concentration, with little or no association between dietary and plasma glutathione among those with lower levels of serum vitamin C and stronger negative correlations among those with higher serum vitamin C levels. These findings indicate that factors regulating plasma glutathione concentration are complex and not simply related to dietary glutathione intake or supply of precursor amino acids.

Ascorbic Acid↗

PubMed1994

Effect of smoking on serum nutrient concentrations in African-American women.

The relationship between current cigarette smoking and serum concentrations of vitamins C, E, and A, and of five carotenoids in human serum were examined in 91 low-income, African-American women. General linear models were used to adjust geometric mean serum concentrations of micronutrients for age, dietary and supplement intakes, total energy intake, alcohol intake, medication use, body mass index, and serum concentrations of cholesterol and triglycerides. Among smokers, serum concentrations of alpha-carotene, beta-carotene, cryptoxanthin, and lycopene averaged only 71-79% of the concentrations among nonsmokers. Mean serum concentrations of vitamins C and E and lutein/zeaxanthin were only slightly lower among smokers relative to nonsmokers, and current smokers had higher serum concentrations of vitamin A. Among current smokers, mean serum concentrations of all five carotenoids decreased with an increase in the amount smoked. The negative effect of smoking on serum concentrations of antioxidant carotenoids may pose a serious health risk in low-income populations already at higher risk for many chronic diseases.

Adult↗

PubMed1994

Iron nutriture in elderly individuals.

The purpose of this review is to examine current research on the iron status of the elderly and factors that influence the body burden of iron. Studies of noninstitutionalized elderly individuals report mean iron intakes that meet current Recommended Dietary Allowances for iron. Dietary practices that may decrease iron bioavailability, and hence iron stores in the body, include low intakes of ascorbic acid or high intakes of calcium, and decreased consumption of highly available iron from meat, fish, and poultry. Although not well documented, the effect of age on iron absorption and iron excretion appears to be small, and body stores of iron increase with age. It is difficult to estimate the prevalence of iron deficiency in elderly persons, because impaired iron status can be the result of iron deficiency or chronic disease. Further study is necessary to determine whether red blood cell ferritin and serum transferrin receptors may be useful biochemical markers to differentiate the anemia of chronic disease from iron deficiency anemia. Hereditary hemochromatosis is a genetic disease that greatly increases the body burden of iron and the risk of hepatic disease among homozygotes. Because iron deficiency or iron excess may impair health, the role of iron in diseases associated with aging such as depressed immune response, neurological dysfunction, cancer, and heart disease is discussed.

Absorption↗

PubMed1994

Technical and scientific developments in exposure marker methodology.

Recent advances in techniques to measure markers of exposure to environmental toxicants in humans are changing the ways in which environmental scientists, epidemiologists, and policymakers characterize and interpret such exposure. In this article we review some major technical and scientific developments in exposure marker methodology for estimating internal dose, with special reference to studies conducted at the US Centers for Disease Control and Prevention. We consider important characteristics of laboratory methods, advances in laboratory technology, analytical standards, and quality assurance of laboratory measurements; comparisons with indirect methods for estimating exposures, such as exposure indices and questionnaires; human pharmacokinetic data; sampling problems; surveillance of human exposures to toxicants; and interpretation of measurements. With a view to increasing the reliability of exposure assessment, we make recommendations for obtaining more data on human exposure to toxicants.

Biomarkers↗

PubMed1994

Retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and four retinyl esters in serum determined simultaneously by reversed-phase HPLC with multiwavelength detection.

We describe the use of HPLC with multiwavelength detection to measure retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, beta-carotene, and the linoleate, oleate, palmitate, and stearate esters of retinol in a single 200-microL serum sample. The method is sensitive enough to detect individual retinyl esters in fasting serum from a nonhyperlipidemic population and requires only 12 min for each sample. Serum concentration ranges and means are reported for retinol, alpha-tocopherol, lutein/zeaxanthin, beta-cryptoxanthin, lycopene, alpha-carotene, trans-beta-carotene, and the sum of the retinyl esters from serum analyses of 3480 participants from several different studies.

Carotenoids↗

PubMed1993

Plasma total glutathione in humans and its association with demographic and health-related factors.

The tripeptide glutathione is proposed to be protective against a number of chronic diseases including cardiovascular disease and cancer. However, there have been few studies of plasma glutathione levels in humans and in those studies the numbers of participants have been very small. In an exploratory analysis the determinants of plasma total glutathione (GSHt) were investigated in a group of 100 volunteers aged 18-61 years in Atlanta, Georgia, USA during June and July 1989. Data on demographic and health-related factors were collected by interview and plasma GSHt was measured using a recently modified laboratory method. The mean concentration of plasma GSHt for all 100 participants was 761 micrograms/l, with a standard deviation of 451 micrograms/l, a range of 86-2889 micrograms/l and a median of 649 micrograms/l. Men had significantly higher levels of plasma GSHt than women (924 v. 692 micrograms/l; P = 0.006). Seventh-day Adventists participating in the present study had higher plasma GSHt levels than other subgroups defined by race and/or religion. Among Seventh-day Adventists consumption of a vegetarian diet was associated with increased plasma GSHt concentration (P = 0.002). Plasma GSHt levels also appeared to vary by race, but relationships with race could not be clearly disassociated from relationships with religion. Among white participants plasma GSHt concentration decreased with age in women but increased with age in men (P = 0.05). Few other factors were associated with plasma GSHt concentration, although use of oral contraceptives (P = 0.10) was somewhat associated with decreased plasma GSHt levels. These findings suggest that plasma GSHt levels may vary with several demographic and health-related attributes and support the need for further research on this potentially important disease-preventive compound.

Adolescent↗

PubMed1992

Glutathione in foods listed in the National Cancer Institute's Health Habits and History Food Frequency Questionnaire.

Glutathione (GSH) is an antioxidant and anticarcinogen that is present in plant and animal tissues that form the bulk of the human diet. Recent studies show that GSH is absorbed intact in rat small intestine and that oral GSH increases plasma GSH concentration in humans. To provide a database for epidemiological studies of dietary intake of GSH and risk of diseases in humans, we have measured the content of GSH in the foods listed in the National Cancer Institute's Health Habits and History Questionnaire. Foods were purchased in the Atlanta area and prepared as most commonly consumed in the United States. GSH analyses were performed using a high-performance liquid chromatography technique with a method of additions to correct for losses during sample preparation. A separate set of samples was run after treatment with dithiothreitol to measure the total of GSH and its disulfide forms (GSH). The results show that dairy products, cereals, and breads are generally low in GSH; fruits and vegetables have moderate to high amounts of GSH; and freshly prepared meats are relatively high in GSH. Frozen foods generally had GSH contents similar to fresh foods, whereas other forms of processing and preservation generally resulted in extensive loss of GSH. Thus this database will allow researchers to examine the relationship between dietary GSH and risk of cancers and other diseases.

Beverages↗

PubMed1991

An evaluation of a food frequency questionnaire for assessing dietary intake of specific carotenoids and vitamin E among low-income black women.

The National Cancer Institute diet questionnaire was evaluated for use in a low-income black population. Data were collected from 91 women aged 30-69 years who were hospital outpatients in Atlanta, Georgia, June through August, 1988. Six ethnic and regional foods added to the questionnaire were found to be important contributors to intakes of several nutrients. Although 17 records were identified as containing probable recording or reporting errors, intakes of carotenes, alpha-carotene, beta-carotene, cryptoxanthin, and vitamin E were significantly and positively associated with serum levels of their referent nutrients. Among nonsmokers, correlation coefficients ranged from 0.32 to 0.45, adjusted for age, body mass index, alcohol and calorie intakes, medications and vitamin supplement use, and serum cholesterol and triglycerides. When questionnaires containing identified errors were omitted, correlations ranged from 0.30 to 0.54. There were no correlations between dietary intakes of lycopene and lutein and blood levels (-0.06 to 0.09). Among smokers, diet-serum correlations were reduced (0.00 to 0.32). These correlations are similar to those reported in research on vitamin E and carotenoids in other populations. These results suggest that the questionnaire is as valid for use in this population as it is in other populations.

Adult↗