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Biomedical subjects

R Ballard-Barbash

Publications and source records attributed to R Ballard-Barbash.

48 records · Page 3Linked to original sources
PubMed1994

Anthropometry and breast cancer. Body size--a moving target.

Body size is one of the few breast cancer risk factors that can be modified throughout life and therefore should be considered in research on breast cancer prevention. The contrasting effects of body size on premenopausal breast cancer compared with postmenopausal breast cancer and the lack of a strong association between body mass and postmenopausal breast cancer in some cohort studies has led to a view that obesity has little influence on breast cancer risk. These conclusions are based on analyses that consider relative weight at one point in time as an adequate measure of lifelong weight patterns and their metabolic consequences. Recent research suggests that, compared to body mass indices, adult weight gain and increased central body fat may be more specific markers of the metabolic consequences of obesity and therefore may predict health outcomes more consistently. Adult weight gain and increases in central body fat, which commonly occur during menopause, have been associated consistently with an increased risk of postmenopausal breast cancer. The timing of weight gain also appears to influence breast cancer risk; increased relative weight and weight gain after menopause have been associated with the largest increases in relative risks. Overall levels of adiposity, increased central fat deposition, and weight gain are associated with alterations in ovarian hormone and glucose metabolism and in growth factors that may promote breast cancer cell growth. Data on lifelong weight changes and the location of fat depots may more precisely identify women with high risk patterns of sex steroid and glucose metabolism. Similarly, research is needed to determine if weight gain during periods of hormonal change, such as menarche, pregnancy, and menopause, have different biologic effects, perhaps because of differences in the location of fat deposition during these periods. Research also is needed on whether there are critical times relative to breast cancer promotion when excessive weight gain should be avoided. Data are lacking on the influence of weight loss or avoidance of weight gain on breast cancer risk or prognosis.

Anthropometry↗
PubMed1991

Tocopherol contents of lipoproteins from frozen plasma separated by affinity chromatography.

We investigated whether freezing and storage of plasma altered alpha-tocopherol levels of whole plasma or the lipoprotein fractions derived from such plasma. Plasma from 24 men, at each of two collection periods, was frozen at -20 degrees C for six weeks, then high-density lipoproteins (HDL) were separated from low- plus very low-density lipoproteins (LDL-VLDL) by heparin affinity chromatography. Whole plasma and the lipoprotein fractions were analyzed for alpha-tocopherol content and compared to counterparts from fresh plasma. Freezing and storage did not reduce alpha-tocopherol levels of plasma or the lipoprotein fractions. alpha-Tocopherol values from fresh and frozen plasma were highly correlated for both plasma (period 1, r = 0.94; period 2, r = 0.93) and the LDL-VLDL fractions (periods 1 and 2, r = 0.97). Percent distribution of alpha-tocopherol between the two lipoprotein fractions was comparable for lipoproteins derived from fresh and frozen plasma. Under the storage conditions used in this study, plasma can be frozen for at least six weeks prior to lipoprotein fractionation with no detectable detrimental effects on alpha-tocopherol content of either plasma or lipoproteins.

Chromatography, Affinity↗
PubMed1991

Effect of fish oil supplementation on the excretion of the major metabolite of prostaglandin E in healthy male subjects.

We investigated the effect of fish oil supplementation on the synthesis of prostaglandin E (PGE) in vivo by measuring the excretion of its catabolite, PGE-M, in 24-hr urine by gas chromatography/mass spectrometry. Forty healthy male volunteers (24-57 years of age) consumed a controlled basal diet providing 40% of energy from fat (P/S ratio about 0.8:1), 130 mg/1000 kcal cholesterol, and a minimum of 22 mg/day of alpha-tocopherol (alpha-T), for three experimental periods lasting a total of 28 weeks. During period 1 (10 weeks) the diet was supplemented with placebo (PO) capsules (15 X 1 g/day) consisting of a blend of fats approaching the fatty acid profile of the basal diet. This was followed by a second 10-week period during which the subjects received 15 X 1 g/day capsules of fish oil concentrate (FOC). During period 3 (8 weeks) they continued the 15 g/day intake of FOC but received an additional 200 mg/day of alpha-T. PO and FOC capsules contained 1 mg alpha-T/g fat as antioxidant. A 14% reduction of PGE-M excretion was observed after 10 weeks of FOC supplementation (period 2), compared to an identical period of placebo supplementation (period 1), P = 0.009. PGE-M excretion during the last week of period 3 was not significantly different from that at the end of period 2. The reduction in PGE synthesis in response to the relatively high marine oil supplementation was large in many subjects participating in this study.

Adult↗
PubMed1991

Effects of omega 3 fatty acids and vitamin E on hormones involved in carbohydrate and lipid metabolism in men.

Forty healthy men were fed diets providing 40% of energy from fat and a minimum of 25 mg vitamin E for 28 wk. During the first 10 wk diets were supplemented with placebo, 15 g mixed fat/d. During the second 10 wk placebo was replaced by 15 g fish-oil concentrate/d. During the last 8 wk 200 mg vitamin E/d was added to fish oil. Compared with placebo, fish-oil feeding significantly increased plasma glucose and decreased triacylglycerol, insulin, glucagon, growth hormone, and somatomedin C. The changes in plasma cholesterol, cortisol, and dehydroepiandrosterone sulphate (DHEA-S) were not significant. Fish oil plus vitamin E further decreased insulin, growth hormone, and DHEA-S and reversed the effect of fish-oil on somatomedin C. The changes in glucose, glucagon, growth hormone, and cortisol were not significant. Thus, changes in plasma glucose and lipids caused by dietary fish oil alone and with fish oil plus vitamin E appear to be due to alterations in hormones involved in carbohydrate and lipid metabolism.

Adult↗
PubMed1991

Increased vitamin E intake restores fish-oil-induced suppressed blastogenesis of mitogen-stimulated T lymphocytes.

We sought to determine whether fish-oil supplementation would suppress blastogenesis in vitro of concanavalin A (ConA)-stimulated peripheral blood mononuclear cells (PBMCs) and, if so, whether it could be reversed with increased intake of vitamin E. Healthy males ate a controlled basal diet providing a total of 40% of energy from fat when fed in conjunction with 15 g/d of either placebo oil (PO) or fish-oil concentrate (FOC) fortified with 15 mg alpha-tocopherol/d for three periods. The subjects were supplemented with PO for 10 wk (PO), with FOC for 10 wk (FOC), and with FOC plus an additional 200 mg alpha-tocopherol/d for 8 wk (FOC+E). During FOC supplementation mitogenic responsiveness of PBMCs to ConA was suppressed, but this effect was reversed by concurrent supplementation with all-rac-alpha-tocopherol (FOC+E). There was a significant positive relationship (P less than 0.001) between plasma alpha-tocopherol concentrations and responsiveness of T lymphocytes to ConA.

Cells, Cultured↗
PubMed1990

Physical activity and risk of large bowel cancer in the Framingham Study.

We examined the relation between self-reported physical activity and large bowel cancer in a prospective cohort of men and women who participated in the Framingham Study. Self-assessments of physical activity were available from the fourth biennial examination on a total of 1906 men and 2308 women aged 30 to 62 yr in 1954. The cohort was followed for up to 28 yr and yielded 152 cases (73 men, 79 women) of large bowel cancer. Inactivity was associated with an increased risk of large bowel cancer among men but not among women. The relative risk estimates for large bowel cancer among men in the middle and lowest tertiles of a physical activity index (compared with the highest tertile) were 1.4 (95% confidence intervals, 0.8-2.6) and 1.8 (1.0-3.2), respectively. Among women the comparable estimates were 1.2 (0.7-2.1) and 1.1 (0.6-1.8), respectively. These findings were unchanged after adjustment for body mass index, serum cholesterol, alcohol, and other potentially confounding variables. The narrow range of physical activity and the minimal heavy activity reported by women in this cohort may have limited our ability to detect an association between physical activity and large bowel cancer among women.

Adult↗
PubMed1990

Association of change in body mass with breast cancer.

We examined the relation between maximal adult change in body mass and breast cancer in the Epidemiological Follow-up Study of the first National Health and Nutrition Examination Survey. A total of 5599 women ages 25 to 74 years at the baseline examination in 1971 to 1975 were analyzed. Adult body mass change was calculated from baseline interview questions on lowest and highest adult weights, ages at those weights, and adult height. The cohort was followed for a median of 10 years and yielded 101 cases of breast cancer. In a multivariate model adjusting for potential confounders (age, body mass, education, parity, age at first birth, menopausal status, calorie and alcohol intake, and physical activity) the relative risk estimates for the upper two tertiles of body mass gain were 1.7 (95% confidence interval, 0.9 to 3.4) and 2.5 (95% confidence interval, 1.2 to 5.4), respectively, in comparison to the lowest tertile of adult body mass gain. The relative risk estimate for those with a loss in body mass during adulthood was 1.3 (95% confidence interval, 0.7 to 2.6) in comparison to those in the lowest tertile of adult body mass gain. There was no association between body mass at the baseline examination and subsequent breast cancer. The results of this study suggest that gain in adult body mass is a predictor of breast cancer risk independent of adult body mass. These results also suggest that avoidance of marked weight gain during adult life may reduce the risk of breast cancer.

Alcohol Drinking↗
PubMed1990

Body fat distribution and breast cancer in the Framingham Study.

We examined the relation between central body fat distribution and breast cancer in a prospective cohort of women who participated in the Framingham Study. At the baseline examination in 1948, a total of 2,201 women aged 30-62 years were analyzed. An index of central to peripheral body fat (the central adiposity ratio) was calculated from the sum of the trunkal skinfolds (chest, subscapular, and abdominal) divided by the sum of the extremity skinfolds (triceps and thigh). These skinfolds were measured at the fourth examination in 1954. The cohort was followed for up to 28 years and yielded 106 cases of breast cancer. When divided into quartiles based on the central adiposity ratio, only women in the fourth quartile (those with the highest central to peripheral body fat distribution) demonstrated an increased risk for breast cancer. The age- and adiposity-adjusted relative risk estimate for having an increased central adiposity ratio (fourth quartile) compared to lower central adiposity ratios was 1.8 (95% confidence interval, 1.2-2.6). Adjustment for potential confounders of height, parity, and education did not appreciably alter this estimate (1.7, 1.1-2.5). There was no association between degree of adiposity, as measured by the sum of the five skinfolds or by body mass index (weight in kg divided by height in m2), and subsequent breast cancer. The results of this study suggest that increased central to peripheral body fat distribution predicts breast cancer risk independently of the degree of adiposity and may be a more specific marker of a premalignant hormonal pattern than degree of adiposity.

Adult↗
PubMed1987

Marine fish oils: role in prevention of coronary artery disease.

Since the early 1970s, investigators have been interested in the relationship between dietary marine fish oils and plasma lipoproteins. Previous studies have shown that consumption of a diet rich in marine fatty acids results in altered lipid profiles, prolonged bleeding times, reduced platelet aggregation, and decreased blood pressure, but the precise mechanisms of action must be examined further. These findings, however, have led to the conclusion that dietary marine fish oils may be of benefit in the prevention of coronary artery disease. Before specific recommendations can be made about their general use, further studies of their long-term efficacy and toxicity must be conducted.

Animals↗
PubMed1987

Breast cancer in residents of Rochester, Minnesota: incidence and survival, 1935 to 1982.

The incidence and survival rates for breast cancer among residents of Rochester, Minnesota, from 1975 to 1982 were compared with rates from 1935 to 1974. The age-adjusted incidence rates of breast cancer, after exclusion of patients with carcinoma in situ, increased 14% between the periods 1965 to 1974 and 1975 to 1982 (from 87.2 to 99.5 per 100,000 person-years). Much of this increase was due to the greater number of patients with less advanced disease: the frequency of both regional lymph node involvement and distant metastatic disease at initial diagnosis decreased. In addition, the incidence of carcinoma in situ more than doubled between the periods 1935 to 1944 and 1975 to 1982. These increased proportions of less advanced disease coincide with increased public and physician awareness of the importance of early detection. No change was demonstrated in overall survival during the study period, perhaps because the follow-up for the final study period was shorter than that for the previous periods. When divided into subsets by staging characteristics, only patients with distant metastatic disease had statistically significant improvement in survival over time (P less than or equal to 0.01)--from a median survival of 21 months in the period 1955 to 1974 to 28 months in the period 1975 to 1982. This increased survival is probably related to advances in therapy (such as combination chemotherapy). In addition, earlier detection of distant metastatic disease in the later study periods might have produced the apparent improvement in survival in this subgroup.

Adult↗
PubMed1986

Estrogen receptors in breast cancer. Association with epidemiologic risk factors.

This study examined the factors influencing estrogen receptor protein levels in a population-based group of 168 incident cases of breast cancer in Olmsted County, Minnesota. The medical histories of women with histologically confirmed breast cancer and measured estrogen receptor levels in the period from November 1977 through December 1982 were reviewed. Statistically significant positive univariate associations were found between tumor estrogen receptor protein level and age, postmenopausal status, nulliparity, late age at first birth, cholelithiasis and educational level. No association was found between tumor estrogen receptor level and other breast cancer risk factors. After adjustment for age, there was no association between the above factors and estrogen receptor protein level. On multivariate analysis, age remained a statistically significant predictor of a higher estrogen receptor protein level. These findings in a population-based group of women with breast cancer are similar to previous reports of hospital-based breast cancer patients.

Adult↗