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Dive into the research topics where Tim Byers is active.

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Featured researches published by Tim Byers.


Epidemiology | 1993

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

Mary K. Serdula; Ralph J. Coates; Tim Byers; Ali H. Mokdad; Sandy Jewell; Noel Chavez; Julie Mares-Perlman; Polly Newcomb; Cheryl Ritenbaugh; Frank A. Treiber; Gladys Block

We evaluated 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 populations 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). Correlation 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. (Epidemiology 1993;4:455–463)


Behavioral Medicine | 1991

Relevance of major stress events as an indicator of disease activity prevalence in inflammatory bowel disease.

Linda C. Duffy; Maria Zielezny; James R. Marshall; Tim Byers; Milton M. Weiser; James F. Phillips; B M Calkins; Pearay L. Ogra; Saxon Graham

The impact of psychological stress in recurrence of inflammatory bowel disease (IBD) is unclear. Why some patients with ulcerative colitis (UC) or Crohns disease (CD) have unrelenting relapses whereas other IBD patients experience long periods of quiescent disease remains an enigma. The authors examined the risk of exposure to major stress events in clinical episodes of IBD. They followed up on 124 persons in a prospective study that monitored behavioral and biological characteristics for a period of 6 months. Stress-exposed subjects demonstrated increased risk of clinical episodes of disease when compared with unexposed subjects (RR = 2.6, 95% CI: 1.3-4.9). Elevated effect measures were highest for the domain of health-related stress (RR = 3.8, 95% CI: 1.5-9.9). In the multiple regression analysis, major stress events remained the most significant indicator of disease activity in the presence of the covariables considered. Only 7% of the variation in disease activity was uniquely attributed to stress. Baseline activity was the other notable indicator of subsequent disease activity in the study sample. All variables considered together explained 52% of the variance observed and implicated factors of potential clinical importance in monitoring recurrence of the disease.


Nutrition and Cancer | 1992

Diet, smoking, and alcohol in cancer of the larynx : a case-control study

Jo L. Freudenheim; Saxon Graham; Tim Byers; James R. Marshall; Brenda P. Haughey; Mya Swanson; Gregg S. Wilkinson

A case-control study among white men in western New York was conducted from 1975 through 1985 to examine diet and other risk factors for laryngeal cancer. Incident pathologically confirmed cases (250) and age- and neighborhood-matched controls (250) were interviewed to determine usual diet and lifetime use of tobacco and alcohol. Cigarettes were strongly associated with risk; pipes and cigars were not. Beer and hard liquor but not wine were associated with increased risk. Dietary fat and carotenoids were related to risk in opposite ways. The upper quartile odds ratio for dietary fat was 2.40 [95% confidence interval 1.26, 4.55], and the upper quartile odds ratio for carotenoids was 0.51 (0.26, 1.01). There was effect modification by smoking. Carotenoids were most negatively associated with risk among the lightest smokers, whereas dietary fat was most positively associated with risk among the heaviest smokers. Total calories, protein, and retinol were associated with increased risk; there was no relationship between laryngeal cancer and vitamin C, vitamin E, carbohydrate, or dietary fiber. This study again demonstrates the strong association between tobacco and alcohol and laryngeal cancer and also suggests that diets low in carotenoids and high in fat may increase risk.


Nutrition and Cancer | 1994

Dietary Glutathione Intake in Humans and the Relationship Between Intake and Plasma Total Glutathione Level

Elaine W. Flagg; Ralph J. Coates; J. William Eley; Dean P. Jones; Elaine W. Gunter; Tim Byers; Gladys Block; Raymond S. Greenberg

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.


Breast Cancer Research and Treatment | 1997

Breast cancer mortality in relation to self-reported use of breast self-examination. A cohort study of 450,000 women.

Lars Holmberg; Anders Ekbom; Eugenia E. Calle; Ali H. Mokdad; Tim Byers

The benefits of breast self-examination (BSE) for reducingmortality from breast cancer are uncertain. We conductedan analysis of the relationship between self-reported practicingof BSE and mortality from breast cancer over13 years in a cohort of over 548,000women. The report of practicing BSE was unrelatedto breast cancer mortality. There was a smallbeneficial effect in those women who were thethinnest, but this effect was small and notstatistically significant. BSE was otherwise equally ineffective insubgroups defined by obesity level and family historyof breast cancer. We conclude that BSE, aspracticed by American women in 1959, did notreduce the risk of mortality from breast cancer.


Epidemiology | 1991

Lag time between stress events and risk of recurrent episodes of inflammatory bowel disease.

Linda C. Duffy; Maria Zielezny; Marshall; Milton M. Weiser; James F. Phillips; Tim Byers; B M Calkins; Saxon Graham; Pearay L. Ogra

We followed a cohort of 124 subjects with a history of inflammatory bowel disease to ascertain risk estimates for clinically active disease associated with exposure to recent stress events. We calculated risk estimates for three lag models (-1, 0, + 1 month). The data indicated a strong association between stress exposures and new clinical episodes of disease (RR = 2.9, 95% Cl: 2.0-4.1), most apparent in the immediate period (lag = 0). Risk estimates were also elevated for extended episodes of disease in subjects under stress compared with unexposed subjects. These results underscore the importance of monitoring stress exposures in prevention and treatment of recurrent disease.


Cancer | 1992

Estimates of costs and effects of screening for colorectal cancer in the united states

Tim Byers; Robin D. Gorsky

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 un‐proven efficacy of the procedure and high costs.


Digestive Diseases and Sciences | 1989

Vasoactive intestinal peptide as a laboratory supplement to clinical activity index in inflammatory bowel disease

Linda C. Duffy; Maria Zielezny; Marie Riepenhoff-Talty; Tim Byers; James R. Marshall; Milton M. Weiser; Saxon Graham; Pearay L. Ogra

Circulating levels of vasoactive intestinal peptide (VIP) in plasma were measured in gauging activity in inflammatory bowel disease (IBD). One hundred-fifteen adult IBD patients were studied cross-sectionally and prospectively, 48 with ulcerative colitis (UC) and 67 with Crohns disease (CD). Sequential samples of plasma were assayed for VIP by specific radioimmunoassay. Sixty males and 55 females, ranging in age from 22 to 76 years were studied over six months. The results revealed a strong, positive association between VIP levels and clinical activity, both at baseline (r=0.38, P<0.001) and follow-up (r=.41, P<0.001). The ability of the VIP immunoassay to gauge clinical activity was also evaluated where VIP concentrations above 30 pg/ml were defined as abnormal. At baseline, sensitivity (specificity) was found to be 81% (55%). The predictive value of a positive (negative) test was 57% (80%). These estimates did not differ at follow-up. Examination of paired plasma samples from intermittently active patients revealed nearly twofold increases (P<0.05) in VIP concentration during active periods of disease. The data suggest that plasma VIP levels may be a valuable laboratory parameter in gauging activity in inflammatory bowel disease.


Preventive Medicine | 1992

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

David S. Freedman; Sheryl L. Lee; Tim Byers; Sarah Kuester; Karen I. Sell

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.


Epidemiology | 1996

Menstrual patterns and breast cancer mortality in a large U.S. cohort.

Heidi Michels-Blanck; Tim Byers; Ali H. Mokdad; Julie C. Will; Eugenia E. Calle

We evaluated risk factors for functional ovarian cysts using data from a case-control study conducted in Milan. Cases were 68 women with histologically confirmed functional cysts. Controls were 272 women admitted to hospital for acute conditions. Compared with women who were 11 years of age or younger at menarche, women who experienced menarche at 12-13 years or at 14 years or later had odds ratios (ORs) of 0.9 [95% confidence interval (CI) = 0.5-1.6] and 0.4 (95% CI = 0.2-0.9). In comparison with women reporting menstrual cycles lasting less than 26 days, the OR was 1.8 (95% CI = 0.7-5.0) in women reporting cycles lasting 26-30 days, 1.8 (95% CI = 0.4-7.4) in those reporting cycles greater than 30 days, and 1.9 (95% CI = 0.4-7.7) in those with totally irregular cycles. Body mass was inversely related to the risk of functional ovarian cysts: compared with women with a Quetelet index below 20, the OR was 0.9 (95% CI = 0.5-1.7) in those with an index in the range from 20-24 and 0.5 (95% CI = 0.2-1.2) in those with an index of 25 or more. We found little relation between the risk of functional ovarian cysts and education, smoking, marital status, or age at first marriage. For oral contraceptive use, we found an OR of 1.3 (95% CI = 0.7-2.6).&NA; We examined the relation between menstrual irregularity and breast cancer mortality in the American Cancer Society Cancer Prevention Study I. In 1959, 428,653 women age 30 years and older completed a questionnaire on possible cancer risk factors, including their recollection of their menstrual pattern at age 20 years. We used proportional hazards analysis to estimate rate ratios, based on 2,226 breast cancer deaths over 13 years of follow‐up. Women who reported having irregular menstruation at age 20 years were at reduced risk for breast cancer mortality (rate ratio = 0.84; 95% confidence interval = 0.74‐0.96). The relation was neither confounded nor modified by other breast cancer risk factors.

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David S. Freedman

Centers for Disease Control and Prevention

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Ali H. Mokdad

Centers for Disease Control and Prevention

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David F. Williamson

Centers for Disease Control and Prevention

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Mary K. Serdula

Centers for Disease Control and Prevention

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Ralph J. Coates

Centers for Disease Control and Prevention

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