Search PubMed⌕ Search

Biomedical subjects

J D Potter

Publications and source records attributed to J D Potter.

At least 181 records · Page 10Linked to original sources
PubMed1994

Age and risk factors for colon cancer (United States and Australia): are there implications for understanding differences in case-control and cohort studies?

Data from two population-based case-control studies were used to investigate the effect of age on colon cancer risk. Dietary intake data were assessed from a study conducted in Utah (United States) between 1979 and 1983; reproductive data were assessed from a study conducted in Adelaide (Australia) between 1979 and 1980. Data from both studies were assessed for their impact on those less than 65 years of age and those 65 or more years of age. Intake of energy, fat, and protein had a greater impact on risk among older men than among younger men. Risk estimates for the upper quartile of intake relative to the lowest quartile of intake were 8.5 (95 percent confidence interval [CI] = 1.7-43.0) for energy, 8.2 (CI = 1.6-41.3) for protein, and 7.2 (CI = 1.6-31.4) for total fat for older men, while comparable risk estimates were 2.4 (CI = 0.6-9.1) for energy, 3.0 (CI = 0.7-13.6) for protein, and 1.9 (CI = 0.5-7.1) for total fat among younger men. Similar trends were seen for older women for energy and protein. beta-carotene decreased colon cancer risk among younger men (odds ratio [OR] = 0.4, CI = 0.1-1.2) and women (OR = 0.1, CI = 0.1-0.5), although not among older men (OR = 1.2, CI = 0.3-4.9) and women (OR = 1.9, CI = 0.6-64). Calcium decreased risk of colon cancer among older men (OR = 0.1, CI = < 0.1-0.8) and younger women (OR = 0.2, CI = < 0.1-0.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Effect of consumption of whole milk and skim milk on blood lipid profiles in healthy men.

A controlled crossover feeding study was conducted in eight males aged 20-36 y to compare the effects of skim milk and whole milk on blood lipids. For 6-wk diet periods, 236 mL/4191 kJ of skim or whole milk was consumed with a background diet designed according to the American Heart Association recommendations. Plasma lipids were analyzed at baseline and at 3 and 6 wk. After 6 wk, the mean total cholesterol concentration was 4.47 mmol/L with skim milk and 4.80 mmol/L with whole milk (P < or = 0.001); mean low-density-lipoprotein-cholesterol concentrations were 2.64 and 2.96 mmol/L, respectively (P < or = 0.001). Mean apolipoprotein B decreased with skim milk and increased with whole milk (P < or = 0.05). No statistically significant differences were observed for plasma high-density lipoprotein-cholesterol, triglyceride, apolipoprotein A-I, or fatty acids. Substitution of skim milk for whole milk may decrease the risk of coronary heart disease.

Adult↗
PubMed1994

Alcohol consumption and colon and rectal cancer in postmenopausal women.

The associations between alcohol and colon and rectal cancers were examined in the Iowa Women's Health Study. In January 1986, 41 837 postmenopausal women, aged 55-69, completed a questionnaire including usual alcohol intake and other information. Through December 1990, 237 incident colon and 75 rectal cancer cases occurred. Mantel-Haenszel age-adjusted relative risks (RR) and 95% confidence intervals (CI) for consumers of < 4.0 and > or = 4.0 g of alcohol per day compared to abstainers were 1.07 (0.61-1.89) and 1.27 (0.72-2.24) (P for trend = 0.46) for rectal cancer. Alcohol intake was inversely associated with distal colon cancer (RR for < 4.0 and > or = 4.0 g of alcohol per day were 0.64 and 0.69 respectively, P for trend = 0.04), which was specific to wine; however, no association was observed with proximal colon cancer (P for trend = 0.94). This is the only report of an inverse association between alcohol and colon cancer in women. Because gut physiology and alcohol metabolism differ between men and women, more research on the association between alcohol and colon cancer in women only, is warranted.

Aged↗
PubMed1994

Does body fat distribution promote familial aggregation of adult onset diabetes mellitus and postmenopausal breast cancer?

Noninsulin-dependent diabetes mellitus and postmenopausal breast cancer share a number of risk factors, including obesity, increased waist-to-hip ratio, and a positive family history. If risk for these diseases is mediated through a familial tendency for abdominal obesity, then one might expect to see familial clustering of both diseases. We analyzed data from a prospective cohort study of 41,837 Iowa women age 55-69 years. Diabetes was not associated with incidence of breast cancer [relative risk (RR) = 0.97]. The association between family history of breast cancer and breast cancer incidence, however, was slightly modified by individual history of diabetes: a positive family history of breast cancer in the absence of baseline diabetes was associated with a relative risk of 1.36 [95% confidence interval (CI) = 1.08-1.70], whereas the presence of both factors was associated with a RR of 1.87 (95% CI = 0.93-3.76). Adjustment for waist-to-hip ratio greatly diminished this difference. Conversely, a family history of breast cancer was associated with a RR of 5-year diabetes mortality of 1.94 (95% CI = 1.17-3.24) that persisted after stratification by tertile of waist-to-hip ratio. No clear association of family history of breast cancer and waist-to-hip ratio for self-reported diabetes incidence was evident. These data are indicative of a complex interrelation between waist-to-hip ratio, familial predisposition, diabetes, and breast cancer.

Adipose Tissue↗
PubMed1994

Egg consumption and cancer of the colon and rectum.

We systematically reviewed 15 previous case-control and cohort studies that examined egg consumption as a risk factor for cancers of the colon and rectum. Nine of the 11 studies of colon cancer reported risk estimates consistent with a positive association; in three of these studies the association was statistically significant. The positive association for egg consumption was generally stronger for females than for males, and for cancer of the proximal, rather than distal colon. Six of eight studies of cancer of the rectum reported risk estimates consistent with a positive association; in two of these studies the association was statistically significant. Notably, in every study that met specific design criteria (defined a priori), risk estimates were consistent with a positive association. Two studies reported seven- to eight-fold increases in risk with high egg consumption. In some studies, positive associations remained after adjustment for intakes of macronutrients or for other food groups. The presence of a variety of bioactive compounds, including cholesterol, lends biological plausibility to a role of egg consumption in the aetiology of colorectal cancer.

Adolescent↗
PubMed1994

Familial aggregation and heritability of waist-to-hip ratio in adult women: the Iowa Women's Health Study.

The aim of this study was to assess evidence that genetic factors influence body fat distribution. First-degree relatives of 324 cancer-free females in a population-based prospective study of 41,837 women (99% white) between the ages of 55 and 69 at baseline in 1986 were studied. A total of 396 living sisters (mean age 65.7 years) and 446 living daughters (mean age 41.2 years) were identified through a mailed 'family tree' questionnaire sent to each participant. Family members were mailed a questionnaire to obtain self-reported measures of current height and weight. A paper tape measure and written instructions were enclosed to obtain waist and hip circumferences. The age-adjusted mother-daughters correlations for waist-to-hip ratio and body mass index (kg/m2) were 0.19 and 0.23, respectively (P < 0.05 using Fisher's z-transformation). The corresponding sister-sister correlations were 0.23 and 0.19, respectively (P < 0.05). The sister-sister correlations were not significantly different from the mother-daughter correlations. After adjustment for body mass index the mother-daughter correlation for waist-to-hip ratio increased to 0.20 and the sister-sister correlation increased to 0.26. These familial correlations suggest that genes and common environment may contribute 40 to 50% of the total variance of waist-to-hip ratio in white women in the Midwest.

Aged↗
PubMed1994

Plasma carotenoids as biomarkers of vegetable and fruit intake.

Higher intakes of vegetables and fruits are associated with a lower risk of certain human cancers. A biomarker of vegetable and fruit intake would be a valuable research tool. A cross-sectional study assessed the association between plasma carotenoid concentrations and intakes of vegetables and fruits. Plasma carotenoids (alpha-carotene, beta-carotene, lutein, beta-cryptoxanthin, and lycopene) were measured in 50 male and 49 female participants, aged 18-37 years, with a wide range of habitual vegetable and fruit intakes. Dietary intakes were assessed via a food frequency questionnaire. Intake of vegetables and fruits and high carotenoid foods were measured. The sum of the plasma carotenoids (excluding lycopene) was highly correlated with intake of total vegetables and fruits (r = 0.59). Of the individual plasma carotenoids, plasma alpha-carotene had the highest correlation with intakes of both total vegetables (r = 0.50) and total fruits (r = 0.58). Intakes of foods with high carotenoid contents were correlated with their corresponding plasma concentrations as follows: high beta-carotene foods (r = 0.41); high lutein foods (r = 0.46); and high lycopene foods (r = 0.11). Multiple regression analyses showed that intake of total vegetables and fruits was the most significant determinant of each plasma carotenoid except lycopene. The utility of combining the plasma carotenoids as biomarkers of vegetable and fruit intake was assessed by a stepwise regression of total vegetable and fruit intake on plasma carotenoids. Significant determinants of intake of total vegetables and fruits were alpha-carotene, beta-cryptoxanthin, lutein, and energy intake (R2 = 0.53).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Evidence for the formation of multiple types of acetaldehyde-haemoglobin adducts.

Acetaldehyde readily reacted with red blood cells and isolated haemoglobin to form adducts. We examined acetaldehyde-haemoglobin reaction products, isolated from red blood cells incubated with acetaldehyde (AcH), for the presence of stable peptide-specific acetaldehyde adducts. Red blood cell incubations were with 20, 50, and 200 mM acetaldehyde for 3, 24 and 48 hr. Peptide-specific [14C]acetaldehyde modifications of Hb from each incubation were identified by tryptic peptide mapping procedures. Nine peptides had modifications and six were found in incubations with 20 mM acetaldehyde. Two of the peptides were acetaldehyde modifications of the Hb alpha- and beta-chain N-termini. Stability studies indicated that the remaining seven [14C]AcH-modified peptides did not result, as can occur under certain conditions, from the transfer of AcH on the N-termini of Hb to N-termini formed after trypsin digestion. An analysis of the relative amounts of [14C]AcH-peptide adducts indicated that at least two of the seven peptides had reactivities for AcH different than the N-termini of Hb; that is, at least two modified peptides differ from imidazolidine-type adducts formed on the N-termini. The presence of multiple modifications with different sensitivities for AcH adduct formation may be useful in developing markers of alcohol consumption.

Acetaldehyde↗
PubMed1993

Association of body fat distribution and family histories of breast and ovarian cancer with risk of postmenopausal breast cancer.

The authors recently published data from a prospective cohort study of postmenopausal women (N Engl J Med 1992;326:1323-9) which suggested that a high waist/hip ratio was associated with a significantly increased risk of breast cancer in women with a positive family history of breast cancer. Since families with aggregations of breast and ovarian cancer demonstrate more consistent genetic linkage to markers on chromosome 17q than do families with breast cancer alone, the authors performed additional analyses to examine whether the previously observed associations with waist/hip ratio differed when family history of breast cancer was partitioned according to whether or not ovarian cancer was also present in a close relative. Between 1986 and 1990, 620 incident cases of breast cancer were identified in a cohort of 37,105 postmenopausal Iowa women. A family history of breast cancer in first-degree relatives was associated with a relative risk of 1.34 (95% confidence interval (CI) 1.07-1.69); a family history of both breast cancer and ovarian cancer was associated with a relative risk of 2.36 (95% CI 1.12-4.98). Consistent with the authors' findings after 4 years of follow-up, a high waist/hip ratio (> or = 80th percentile vs. < 80th percentile) was associated with increased risk of breast cancer in the presence of a family history of breast cancer (relative risk (RR) = 2.10, 95% CI 1.43-3.09) but not in the absence of a family history of breast cancer (RR = 1.12). The combination of a high waist/hip ratio with a family history of breast and ovarian cancer was associated with 4.83-fold increased risk (95% CI 1.55-15.1). Neither a family history of breast cancer nor a family history of ovarian cancer was associated with significantly increased risk in the absence of a high waist/hip ratio.

Adipose Tissue↗
PubMed1993

Reduced risk of colon cancer with high intake of vitamin E: the Iowa Women's Health Study.

Antioxidant micronutrients, including vitamin E, vitamin C, the carotenoids, and selenium, defend the body against free radicals and reactive oxygen molecules, suggesting a potential for these dietary components in cancer prevention. To investigate whether high intakes of antioxidant micronutrients protect against colon cancer in humans, we analyzed data from a prospective cohort study of 35,215 Iowa women aged 55-69 years and without a history of cancer who completed a dietary questionnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, total vitamin E intake was inversely associated with the risk of colon cancer (P for trend < 0.0001); the relative risk for the highest compared to the lowest quintile was 0.32 [95% confidence interval (95% CI) 0.19, 0.54]. Further adjustment for total energy intake and other risk factors in proportional hazards regression had little effect on these estimates. The association was not uniform across age groups: the multivariate relative risk of colon cancer for the highest compared to the lowest quintile of total vitamin E intake was 0.16 (95% CI 0.04, 0.70) for those 55-59 years old, 0.37 (95% CI 0.12, 1.16) for those 60-64 years old, and 0.93 (95% CI 0.27, 3.25) for those 65-69 years old. Multivariate-adjusted relative risks among women with higher total intakes of vitamins A and C and beta-carotene, and among users of selenium supplements, were not significantly different from 1.0. These prospective data provide evidence that a high intake of vitamin E may decrease the risk of colon cancer, especially in persons under 65 years of age.

Aged↗
PubMed1993

Transfusion history and cancer risk in older women.

OBJECTIVE: To test the hypothesis that history of blood transfusion is associated with an increased incidence of cancer in older women. DESIGN: Prospective cohort study. SETTING: General community in the state of Iowa. PARTICIPANTS: Random sample of 37,337 cancer-free Iowa women ages 55 to 69 years. MEASUREMENTS: Transfusion history was assessed with a mailed questionnaire completed in January 1986. Cancer incidence in 5 years was ascertained by a population-based cancer registry. RESULTS: Women who had ever received a blood transfusion were at an increased risk for non-Hodgkin lymphoma (relative risk (RR) = 2.20; 95% CI, 1.35 to 3.58) and kidney cancer (RR = 2.53; CI, 1.34 to 4.78). The relative risks for these cancers were greater with decreasing time from first transfusion. No increased risk occurred for cancers of the breast, lung, uterine corpus, ovary, pancreas, colon, rectum, skin (melanoma), or for all cancers considered together. CONCLUSION: These findings suggest that previous blood transfusion may be a risk factor for non-Hodgkin lymphoma and kidney cancer but is not associated with the most common neoplasms.

Age Factors↗
PubMed1993

Relation of calcium, vitamin D, and dairy food intake to incidence of colon cancer among older women. The Iowa Women's Health Study.

To investigate whether a high intake of calcium, vitamin D, or dairy products may protect against colon cancer, the authors analyzed data from a prospective cohort study of 35,216 Iowa women aged 55-69 years without a history of cancer who completed a dietary questionnaire in 1986. Through 1990, 212 incident cases of colon cancer were documented. Adjusted for age, intakes of calcium and vitamin D were significantly inversely associated with the risk of colon cancer. The relative risks for the highest quintile of intake as compared with the lowest were 0.52 (95% confidence interval (CI) 0.33-0.82) for calcium and 0.54 (95% CI 0.35-0.84) for vitamin D. After multivariate adjustment, the trends were no longer statistically significant and the relative risks for the highest versus the lowest quintiles of calcium and vitamin D intakes were attenuated: 0.68 (95% CI 0.41-1.11) for calcium and 0.73 (95% CI 0.45-1.18) for vitamin D. Although the multivariate-adjusted findings did not reach statistical significance at p < or = 0.05, when considered in the context of the whole body of literature on this subject, they are consistent with a possible role for calcium or vitamin D in modestly reducing colon cancer risk.

Aged↗
PubMed1993

Food-group consumption and colon cancer in the Adelaide Case-Control Study. I. Vegetables and fruit.

Previous epidemiologic studies have shown an inverse association between vegetable and fruit consumption and risk of colon cancer. Vegetables and fruit contain a large number of potentially anti-carcinogenic substances, thus lending biological plausibility to this association. We conducted a case-control study in Australia, comparing 220 persons with histologically confirmed incident adenocarcinoma of the colon with 438 age- and gender-matched controls. Cases were identified via the South Australian Cancer Registry (1979-80); controls were randomly selected from the electoral roll. All participants completed a 141-item food-frequency questionnaire and were interviewed regarding demographic and other information. Consumption of 15 vegetable and fruit groups was investigated. Odds ratios (OR) for quartiles of consumption were derived using conditional logistic regression. All analyses were conducted separately for females and males. For females, greater intakes of onions and legumes were associated with decreased risk, with protein-adjusted OR of 0.48 and 0.53 respectively. Greater intakes of raw fruit and cabbage were associated with protein-adjusted OR of 0.76 and 0.71 respectively. For males, greater intakes of onions, green leafy vegetables, legumes, carrots and cabbage were associated with protein-adjusted OR in the range of 0.72 to 0.77. Consumption of potatoes was positively associated with risk in both genders. All 95% confidence intervals included 1.0. Analyses stratified by colon-cancer sub-site showed no strong and consistent differences between sub-sites for the vegetable and fruit associations. Results for meat, poultry, seafood, dairy foods and eggs are presented in a companion report.

Adult↗
PubMed1993

Food-group consumption and colon cancer in the Adelaide Case-Control Study. II. Meat, poultry, seafood, dairy foods and eggs.

We conducted a case-control study in Australia, comparing 220 persons with histologically confirmed incident adenocarcinoma of the colon with 438 age- and gender-matched controls. Cases were identified via the South Australian Cancer Registry (1979-80); controls were randomly selected from the electoral roll. All participants completed a 141-item food-frequency questionnaire and were interviewed regarding demographic and other information. Consumption of 8 groups of foods from animal sources was investigated. Odds ratios (OR) for quartiles of consumption were obtained using conditional logistic regression. All analyses were conducted separately for females and males. The most striking finding was a positive association for egg consumption in females, with an unadjusted OR of 2.4 (1.1-5.3) for consumption in the uppermost quartile. The uppermost septile of egg consumption was associated with an unadjusted OR of 6.3 (1.5-26.1) and a dose-response pattern was suggested. Intakes of red meat, liver, seafood, and dairy foods were also weakly positively associated with risk in females. In males, intakes of red meat and poultry were weakly positively associated with risk with unadjusted ORs of 1.5 (0.8-2.8) and 1.4 (0.7-2.6) respectively. The ratio of intake of red meat to poultry and seafood was also positively associated with risk in males, with an unadjusted OR of 1.4 (0.8-2.6). Interpretation of analyses stratified by colon cancer subsite was limited by the low number of subjects in each sub-site stratum, yet the results were somewhat supportive of a stronger risk associated with animal foods in the proximal than in the distal colon. The results for egg consumption suggest a role for cholesterol in the etiology of colon cancer, particularly in proximal cancer for females. Results for vegetable and fruit consumption are presented in a companion report.

Animals↗
PubMed1993

Vegetables, fruit, and lung cancer in the Iowa Women's Health Study.

Previous epidemiological studies have shown an inverse association between vegetable and fruit consumption and lung cancer risk; few of these studies have been prospective or have focused upon women. In 1986, we assessed food intake in 41,837 Iowa women, aged 55 to 69 yr, with a mailed 127-item food frequency questionnaire. After 4 years of follow-up, 179 incident cases of lung cancer were identified via the Iowa Surveillance, Epidemiology, and End Results cancer registry. After specific exclusion criteria were applied, a nested case-control comparison of 138 cases with 2,814 randomly selected noncases was undertaken. Intakes, in the upper-most quartile, of 11 vegetable and fruit groups, as well as of the nutrients beta-carotene and vitamin C, were explored. High intakes of all vegetables and fruit, all vegetables, and green leafy vegetables were each associated with an approximate halving of risk: age-, smoking-, and energy-adjusted odds ratios (ORs) were 0.49 (95% confidence interval, 0.28-0.86), 0.50 (95% confidence interval, 0.29-0.87), and 0.45 (95% confidence interval, 0.26-0.76), respectively. A lower lung cancer risk was also seen for all fruit (adjusted OR = 0.75 for high consumption), high vitamin C vegetables and fruit (OR = 0.75), carrots (OR = 0.71), and brocolli (OR = 0.72) and for the nutrients beta-carotene (OR = 0.81) and vitamin C (OR = 0.81) (all 95% confidence intervals included 1.0). Lung cancer risk was unrelated to consumption of the three food groups defined as "high-carotenoid" (beta-carotene, lutein, and lycopene) and tomatoes. In an analysis stratified by histological type of lung cancer, the strongest inverse associations for vegetables and fruit were seen for large cell carcinoma. Analysis by smoking status showed the inverse associations for most vegetable and fruit groups with lung cancer risk to be stronger for exsmokers than for current smokers. Results from the stratified analyses must be interpreted with caution because of the small number of cases in each stratum.

Aged↗
PubMed1993

Body fat distribution and 5-year risk of death in older women.

OBJECTIVE: To test the hypothesis that both body mass index (expressed as the ratio of weight in kilograms per height in meters squared) and the ratio of waist circumference to hip circumference are positively associated with mortality risk in older women. DESIGN: Prospective cohort study with a 5-year follow-up period. SETTING: General community. PARTICIPANTS: Random sample of 41,837 Iowa women aged 55 to 69 years. MAIN OUTCOME MEASURE: Total mortality (1504 deaths). MAIN RESULTS: Body mass index, an index of relative weight, was associated with mortality in a J-shaped fashion: rates were elevated in the leanest as well as in the most obese women. In contrast, waist/hip circumference ratio was strongly and positively associated with mortality in a dose-response manner. Adjusted for age, body mass index, smoking, education level, marital status, estrogen use, and alcohol use, a 0.15-unit increase in waist/hip circumference ratio (eg, a 15-cm [6-in] increase in waist measurement in a woman with 100-cm [40-in] hips) was associated with a 60% greater relative risk of death. The observed associations were not explained to any great degree by bias from weight loss prior to baseline or higher early deaths among lean participants. CONCLUSIONS: Waist/hip circumference ratio is a better marker than body mass index of risk of death in older women. Waist/hip circumference ratio should be measured as part of routine surveillance and risk monitoring in medical practice.

Adipose Tissue↗
PubMed1993

Calcium and colorectal epithelial cell proliferation: a preliminary randomized, double-blinded, placebo-controlled clinical trial.

BACKGROUND: Colonic epithelial cell proliferation is increased in patients at high risk for colon cancer. Calcium administration has ameliorated the proliferative changes in rodents, and findings in small, uncontrolled clinical trials have suggested similar effects in humans. PURPOSE: This preliminary, double-blind, randomized clinical trial was designed 1) to investigate whether supplemental calcium will reduce colonic epithelial cell proliferation in patients with sporadic adenomas who consume a high-fat, Western-style diet; 2) to determine the sample size (number of scorable crypts per person) needed to achieve adequate statistical power; and 3) to evaluate the feasibility of full-scale clinical trials. METHODS: Twenty-one sporadic adenoma patients were treated daily with placebo or 1200 mg of supplemental calcium. To determine colonic epithelial cell proliferation, we used tritiated thymidine labeling of colon crypt epithelial cells in rectal biopsy specimens and calculated the percentage of labeled cells (labeling index [LI]). Two pathology technician "readers" independently scored each specimen, and inter-reader reliability was determined. Subjects remained on their usual diet during the study, and intake of calories, calcium, total fat, and vitamin D did not differ substantially among them. We calculated curves for statistical power to determine the number of scorable crypts needed per person for detection of a statistically significant difference (P < .05) of 1.0% in mean LI. RESULTS: The pooled baseline LI was 4.7%. In the calcium-treated group, the LI increased 0.6% (proportional increase, 12.8%); in the placebo-treated group, it decreased 0.5% (proportional decrease, 10.6%). The difference between change in the mean LI from baseline to 8 weeks' follow-up in the placebo group versus the calcium group was not statistically significant. The intraclass correlation coefficient for inter-reader reliability for the baseline LI was .66. Analyses indicated scoring eight crypts sufficient for estimates of the LI adequate for between-group comparisons, a level achieved in 81% of biopsy specimens. CONCLUSIONS: Calcium carbonate supplements delivering 1200 mg elemental calcium daily may not decrease colonic epithelial cell proliferation over an 8-week period in sporadic adenoma patients. In future trials measuring the LI, consideration should be given to ensuring adequate numbers of scorable crypts and to the impact of inadequate biopsy procedures, labeling failure, reader reliability, and participant withdrawal. Our findings support the feasibility of a full-scale clinical trial to further study the relationships among dietary calcium, colonic epithelial cell proliferation, and colorectal cancer.

Adenoma↗