Prospective case-cohort study of intestinal colonization with enterococci that produce extracellular superoxide and the risk for colorectal adenomas or cancer.

OBJECTIVE: The aim of this study was to determine whether intestinal colonization with enterococci that produce extracellular superoxide (O2*-), a free radical implicated in the development of colorectal cancer, is associated with these lesions or their precursors. METHODS: A prospective case-cohort study was performed by isolating enterococci from stools of consecutive patients undergoing colonoscopy who had no prior history of colonoscopy or colorectal cancer. A food frequency questionnaire was also administered to control for dietary factors known to affect the risk for these lesions. RESULTS: Among 159 evaluable participants were 77 with no precancerous or cancerous pathology, 61 with adenomas <2 cm, 10 with adenomas > or =2 cm, and 11 with cancer. Regression analyses found no associations for those subjects with adenomas of any size or with cancer and colonization with O2*--producing enterococci, any nutrient, or age. For those patients with large adenomas > or = 2 cm or cancer, however, significant associations were noted for age (OR 1.94 per decade, 95% CI 1.2-3.5), beta-carotene (OR 0.44 per 500 microg/1000 kcal/day, 95% CI 0.2-0.8), vitamin A (OR 3.20 per 500 microg/1000 kcal/day, 95% CI 1.2-8.9), and vitamin E (OR 0.09 per 10 mg/ 1000 kcal/day, 95% CI 0.006-0.9), but not colonization with O2*--producing enterococci. Second stools collected 1 yr later, however, often contained dissimilar enterococcal flora, undermining an important study assumption. CONCLUSIONS: Significant associations were found for those with large adenomas or cancer (but not small adenomas), with age, and with foods enriched for vitamin A, vitamin E, and beta-carotene. An association between colonization with O2*--producing enterococci and colorectal adenomas or cancer, however, could not be ascertained, possibly because intestinal enterococcal flora changes over time, leaving a potentially cohesive hypothesis of colon cancer and risk factors as yet unanswered.

Changes in the plantaris muscle as an indicator of alterations in lean body mass of obese Zucker rats following prolonged energy restriction and subsequent partial recovery.

To study the effects of a prolonged (80 day), severe (64% body mass loss) energy restriction and subsequent refeeding on skeletal muscle tissue, specifically the plantaris muscle, 21 genetically obese Zucker rats were selected for this study. Six rats were initially killed and served as baseline (BASE), then 15 rats underwent severe energy restriction for 80 days. Seven of these restricted rats (RESTRICT) were then killed and assessed while the other eight rats (REHAB) were fed a dry rehabilitation diet that provided 100% of the recommended energy and 1.5 times the recommended protein for growth. Once the REHAB rats had recovered approximately 45% of their original mass loss, these animals were then evaluated. Within 20 min after being killed, the plantaris muscles from each animal in each group had been removed, weighed, and frozen. Analyses included total plantaris mass, as well as differences in fiber diameters, esterase activity, and fiber type distributions between three groups (BASE, RESTRICT, and REHAB). The extreme body mass loss of 64% in genetically obese Zucker rats resulted in significant tissue weight loss and reduced fiber diameters in the plantaris muscle. Refeeding resulted in larger muscle fiber diameters that approached baseline values but an 11% difference in muscle weight remained and may be due to a decreased fiber number. Esterase activity seemed to indicate an initial fat utilization for the RESTRICT group, followed by suppressed esterase activity in the REHAB group, suggesting increased fat storage. No significant differences were found in fiber type distribution between BASE, RESTRICT, or REHAB animals.

Basal cell carcinoma and lifestyle characteristics.

BACKGROUND: A number of lifestyle factors are important in the etiology of basal cell carcinoma. Previous studies have investigated smoking, alcohol, diet, and sun exposure as possible contributing factors. No previous studies have investigated case-controlled lifestyle influences in basal cell carcinomas referred for Mohs micrographic surgery. METHODS: Cases were obtained from Mohs-referred basal cell carcinoma patients. Matched controls were selected from a busy dermatology clinic. The only criteria for selection of controls was never having had cancer previously. Cases and controls were surveyed regarding lifestyle characteristics. RESULTS: Forty-six age, sex, and skintype-matched controls were compared. Sun exposure, alcohol, and smoking were not significant factors. Dietary fat, fiber, and the vitamins A, C, and beta carotene, as well as selenium showed important, but not significant differences. Caffeine consumption was higher in the cancer group. CONCLUSIONS: Our findings agree with previously published studies in regard to antioxidant consumption as a protective factor for basal cell carcinoma. Caffeine consumption was higher in the cancer patients.

Soluble fiber and serum lipids: a literature review.

Although fiber has been increasingly recognized as an important dietary constituent, controversy and confusion still exist about the physiologic effects of fiber. Specifically, the independent ability of dietary fiber to lower serum lipid levels is controversial. The purpose of this article is to review available evidence regarding the impact of soluble fibers on serum lipid levels. Soluble fibers appear to have a greater potential to alter serum lipid levels than do insoluble fibers. Significant reduction in the level of serum total cholesterol by soluble fiber was found in 68 of the 77 (88%) human studies reviewed. Of the studies measuring low-density lipoprotein cholesterol, 41 of 49 (84%) reported significant reductions. No significant changes were reported in 43 of the 57 (75%) studies that reported high-density lipoprotein cholesterol and/or in 50 of the 58 (86%) studies that measured triglyceride levels.

Brief communication: dietary habits of first-year medical students as determined by computer software analysis of three-day food records.

Nutrition training for medical students has long been a low priority for most medical schools. Given the growing body of knowledge linking health promotion to proper dietary habits, there is a need to increase the quantity and quality of nutrition training for medical students. In the present study, first-year medical students recorded food intake for 3 days and analyzed their diets for nutrient contents with a computer software program. Use of the interactive software created a personalized approach to increasing nutrition knowledge as the students became aware of their own dietary habits. Female students had a low consumption of kilocalories, dietary fiber, calcium, iron, zinc, potassium, and polyunsaturated fat. Male students exceeded current recommended intakes for fat, saturated fat, cholesterol, and sodium.

Cellular development of skeletal muscle of rats during recovery from prolonged undernutrition.

The cellular basis for growth retardation of skeletal muscle was studied in male Sprague-Dawley rats. At birth, animals were assigned to control (C) or food-restricted (R) groups. During lactation, food intake of the pups was reduced by limiting intake of the mother to 50% of controls. After weaning, pups received 40% of ad libitum intakes until 120 d of age. From 120 to 316 d, all animals were fed ad libitum. At 120 d, body weight of the R group was 41% of C and muscle and adipose weights were 54 and 16% of C, respectively. Muscle DNA in the R group was 47% of C, but protein-to-DNA ratio was normal. Fiber number was not different between C and R groups; however, muscle length and fiber cross-sectional area were 85 and 64%, respectively, of C values. After 196 d of recovery, weights of the body, skeletal muscles and adipose tissues averaged 76, 84 and 51% of C values, respectively. Recovery of skeletal muscle paralleled the recovery of fiber cross-sectional area (84%) and DNA content (86%). Daily injections of 100 micrograms of growth hormone from 120 to 148 d produced no additional recovery. This study establishes that growth retardation of skeletal muscle is associated with reductions in the development of cross-sectional area and DNA content of muscle fibers.

Loss of tissues in female rats subjected to food restriction during lactation or during both gestation and lactation.

The effects of food restriction (50% of ad libitum-fed controls) on maternal tissues during lactation (LR) or during both gestation and lactation (GLR) were examined in rats. Skeletal muscle protein, RNA and fiber diameter were reduced in response to the LR and GLR treatments, but muscle DNA and fiber number were unchanged. Mean body weights of the pregnant (GLR) and nonpregnant female rats were not significantly different after the first 3 wk of food restriction (after delivery in pregnant GLR rats). Compared to the controls, pups of the GLR females had a significantly smaller mean birth weight. The LR females lost weight and catabolized fat pads, organs, and skeletal muscles while nonlactating females gained weight when given a similar amount of food. These results indicated that the demands of gestation did not significantly add to the loss of maternal body weight due to the restriction of food intake. However, the demands of lactation caused the food-restricted females to catabolize significant amounts of maternal tissues.

Cellular growth of skeletal muscle in weanling rats during dietary restrictions.

The effects of feeding varying levels of a nutritionally balanced diet on the cellular growth of rat skeletal muscles were examined. Groups of male weanling rats were fed 50% (R-50), 40% (R-40), or 30% (R-30) of the intake of the ad libitum fed age-matched controls (C). An initial control group (IC) was killed at 25 days of age, and all other groups were sacrificed at 46 days. These chronic dietary restrictions slowed the rates of growth of each of the four skeletal muscles examined: the plantaris, soleus, extensor digitorum longus, and gastrocnemius. Longitudinal growth, as estimated from tibia length, was also significantly affected by the restrictions. DNA, protein, and RNA were examined in the plantaris. DNA content was the same in the IC and R-30 groups but increased significantly with each subsequent increase in food intake. The ratio of protein/DNA was the same for the C, R-50, and R-40 groups but was 15% lower for the R-30 group. Therefore, the restricted rats tended to maintain the normal ratio of protein/DNA even at the expense of halting DNA replication. While the transverse growth (cross-sectional area of muscle fibers) of the plantaris was significantly slowed by the chronic restrictions, muscle fiber number was the same for all groups at 46 days of age. These data indicate that in skeletal muscle, DNA content (nuclear number) does not equate with cell number, and the ratio of protein/DNA does not reflect cell size. Furthermore, nuclear number, not cell number, appears to be the major factor controlling postnatal skeletal muscle growth.