Effect of mammalian lignans on the growth of prostate cancer cell lines.

BACKGROUND: Mammalian lignans, enterolactone (EL) and enterodiol (ED), have been shown to inhibit breast and colon carcinoma. To date, there have been no reports of the effect of lignans on prostatic carcinoma. We investigated the effects of ED and EL on three human prostate cancer cell lines (PC-3, DU-145 and LNCaP). MATERIALS AND METHODS: Cells were treated with either 0.1% (v/v) DMSO (vehicle) or 10-100 microM of EL, ED or genistein (positive control) for 72 hours. Cell viability was measured by the propidium iodide nuclei staining fluorometric assay with each assay performed in triplicate. RESULTS: At 10-100 microM, EL significantly inhibited the growth of all cell lines, whereas ED only inhibited PC-3 and LNCaP cells. While EL was a more potent growth inhibitor than ED, both were less potent than genistein. The dose for 50% growth inhibition of LNCaP cells (IC50) by EL was 57 microM, whereas IC50 was 100 microM for ED, (the observed IC50 for genistein was 25 microM). CONCLUSION: ED and EL suppress the growth of prostate cancer cells, and may do so via hormonally-dependent and independent mechanisms.

Estrogen profiles in postmenopausal African-American women in a wheat bran fiber intervention study.

High dietary fiber intake has been hypothesized to lower blood estrogen concentrations, an effect thought to be beneficial for decreasing breast cancer risk. This study investigated the association between dietary supplementation of wheat bran and circulating estrogen levels in postmenopausal African-American women participating in a community intervention trial. Seventeen postmenopausal women (aged 63 +/- 1.6 yr) participated in the study. Nutritional status was assessed and blood and 24-hour urine samples were collected before and after five to six weeks of daily supplementation of the diet with 35 g of wheat bran cereal (11.6 g insoluble dietary fiber) marked with 28 mg of riboflavin. Riboflavin confirmed that all postmenopausal participants adhered to the intervention protocol. Nine of the 17 postmenopausal women were taking some form of estrogen replacement therapy (PM-ERT). Baseline hormone levels in the PM-ERT group did not significantly change after the dietary intervention. Estradiol (96.8 +/- 20.3 vs. 113.8 +/- 23.3 pg/ml), androstenedione (0.47 +/- 0.06 vs. 0.45 +/- 0.06 ng/ml), and sex hormone-binding globulin (SHBG, 107 +/- 13.5 vs. 106.6 +/- 13.3 nmol/l) levels remained constant. In the eight postmenopausal women who were not receiving exogenous hormones (PM), wheat bran consumption was not associated with predicted decreased levels of estradiol (25.7 +/- 2.7 vs. 31.0 +/- 1.9 pg/ml), estrone (38.3 +/- 10.1 vs. 39.3 +/- 10.6 pg/ml), and androstenedione (0.78 +/- 0.08 vs. 0.68 +/- 0.11 ng/ml) or with increased concentrations of SHBG (35.2 +/- 6.4 vs. 34.8 +/- 6.5 nmol/l). Participants receiving ERT had baseline and postintervention levels of estradiol and SHBG significantly higher and androstenedione significantly lower than those not receiving ERT. No association between wheat bran supplementation and hormone levels was found in PM or PM-ERT African-American participants. These results in postmenopausal women are in contrast to findings of earlier studies in premenopausal women indicating that wheat bran fiber decreases serum sex hormones. Estrogen levels in postmenopausal women are only 5-10% of those in premenopausal women; therefore, a high wheat bran fiber diet alone may not be sufficient to depress these low levels even further.

Development of a urinary riboflavin adherence marker for a wheat bran fiber community intervention trial.

Development of a reliable marker of adherence to high-fiber diets is essential for accurately assessing dietary fiber intake in community interventions and clinical trials. The objective of this study was to evaluate the feasibility of using a riboflavin tracer incorporated into wheat bran cereal to determine fiber intake and compare results to the more traditional methodology of measuring stool weight. The inpatient phase of the study established that the excretion of urinary riboflavin was highly correlated with the dose of the riboflavin-spiked wheat bran cereal (r = 0.95, P < 0.005) and could be used as a biomarker to validate fiber supplement intake. The outpatient clinical intervention included a group of seven African-American men and women, who were asked to incorporate 1/2 cup of wheat bran cereal (11.6 g of dietary fiber) into their daily diet for a 6-week period. The cereal was spiked with a 28-mg dose of riboflavin. Baseline measurements of urinary riboflavin and stool weight were compared to postintervention levels. Comparison of pre- and postintervention measures of riboflavin excretion showed a significant increase (0.8 +/- 0.1 versus 6.0 +/- 0.6 mg/day, P < 0.02), which confirmed a high level of adherence to the dietary intervention. Although wet stool weights at baseline were significantly lower than postintervention (106 +/- 20 versus 146 +/- 23 g/day; P < 0.03), differences in dry stool weights did not reach significant levels (28 +/- 4 versus 33 +/- 5 g/day, P < 0.30). Furthermore, pre- and poststool measurements overlapped and could not provide definitive data on participant adherence. These results indicate that the riboflavin tracer was a more sensitive biomarker of wheat bran fiber supplementation than stool weight and provided an accurate method for validating adherence to the dietary intervention. A riboflavin marker provides a valid technique for adherence assessment in large-scale community trials, in which collection of 3-day fecal samples is not a manageable option.

Inhibition of rat mononuclear cell leukemia by corn oil gavage: in vivo, in situ and immune competence studies.

Corn oil administered by oral gavage decreases the spontaneous incidence of mononuclear cell leukemia (MNCL) in male Fischer rats used as vehicle controls in long-term carcinogenesis experiments. We used an MNCL transplant model, an in situ MNCL cell proliferation assay and immune competence assays to explore mechanism(s) underlying the effects of corn oil gavage on MNCL development in male rats. Relative to non-gavaged or water-gavaged rats, corn oil-gavaged rats had approximately 25% lower MNCL incidence as well as longer MNCL latency and increased survival. There were no differences in body weight or caloric intake between treatment groups, as corn oil-gavaged rats compensated for calories supplied by the gavaged oil by consuming less food. These data indicate that transplanted MNCL cells grew slower in corn oil-gavaged rats than in non-gavaged or water-gavaged rats and suggest that corn oil gavage may exert its effects through a decrease in protein or other nutrients. Five-day proliferation rates of cultured MNCL cells in diffusion chambers implanted in male corn oil-gavaged rats were 40% less than in water-gavaged rats, suggesting nutrition-sensitive endogenous factors mediate the suppression of MNCL cell proliferation in corn oil-gavaged rats. Corn oil-gavaged rats had 54% lower serum growth hormone (GH) levels, and replacement of GH into corn oil-gavaged rats by osmotic minipump infusion increased in situ MNCL cell proliferation to rates observed in water-gavaged animals. Corn oil-gavaged rats also showed enhanced cellular immune competence as measured by mitogen stimulation, natural cytotoxicity and immunofluorescence assays. Taken together, these findings suggest corn oil administered by oral gavage may decrease MNCL development by slowing MNCL cell proliferation, mediated at least in part by altered levels of diffusible factors such as GH, and/or by enhancing immune competence.

The growth hormone: insulin-like growth factor 1 axis is a mediator of diet restriction-induced inhibition of mononuclear cell leukemia in Fischer rats.

A leukemia cell transplant model and both in situ and in vitro bioassays were used to assess the roles of endogenous factors in mediating diet restriction (DR)-induced inhibition of mononuclear cell leukemia (MNCL) in Fischer 344 rats. DR-treated male rats (n = 35), which were fed 75% of ad libitum (AL) intake of NIH-07 open formula diet, had lower transplanted MNCL incidence (54 versus 77%; P = 0.039) with longer latency (P = 0.015) and decreased severity (P = 0.01) than AL-treated rats 12 weeks after inoculation with MNCL cells. Five-day proliferation rates of cultured MNCL (CRNK-16) cells in diffusion chambers implanted in DR-treated rats were 22% less than in AL-treated rats (P = 0.03), indicating that DR-dependent diffusible factor(s) modulate in situ MNCL cell growth. Serum from DR-treated rats supported lower in vitro CRNK-16 cell proliferation rates relative to serum from AL-treated rats. Serum levels of both growth hormone (GH) and insulin-like growth factor 1 (IGF-1) were over 50% lower in DR- versus AL-treated rats. An evaluation of the in vitro cell proliferative activity of a panel of purified factors showed that GH and IGF-1, but not 15 other growth factors, stimulated thymidine incorporation in CRNK-16 cells. Infusion of either GH or IGF-1 via osmotic minipumps restored in situ and in vitro CRNK-16 cell proliferation in DR-treated rats up to rates measured in AL-treated rats. Splenocytes from DR-treated rats, relative to AL-treated rats, were more sensitive to mitogen stimulation, displayed increased cell surface expression of receptors for class 1 and 2 major histocompatibility complex molecules, and were more cytotoxic to target tumor cells. Infusion of either GH or IGF-1 in DR-treated rats further enhanced mitogen responsiveness and natural cytotoxicity but reversed the DR-induced increase in major histocompatibility complex receptors. We conclude that DR modulates MNCL progression in Fischer 344 rats through both its influence on MNCL cell proliferation via suppression of the GH:IGF-1 axis and its enhancement of host defenses against tumor cells.

Diet and human leukemia: an analysis of international data.

BACKGROUND: There has been little direct exploration of the relationships between dietary factors and human leukemia; however, a number of literature reports from animal studies and correlation analyses between countries suggest that diet can influence leukemia risk. METHODS: Statistical analyses of international food supply data and leukemia incidence data were performed to define better the diet-human leukemia relationship. Incidence data for lymphoid, myeloid, and total leukemia (all leukemia subtypes combined) from 24 countries with reliable cancer registry data were regressed with estimates of per capita disappearance of macronutrients and alcohol, as well as gross national product and average height. RESULTS: Simple correlation analyses showed that the dietary variables were associated with leukemia in a gender- and site-specific fashion. Males consistently had higher correlations than females. The strongest correlations were found between total calorie intake and both lymphoid and total leukemia incidence, especially among males. Myeloid leukemia in either gender was most strongly associated with gross national product. To control for potential confounding, multiple regression analyses were performed, with all regression models adjusted for gross national product, height, and dietary covariates. Total calorie supply was the only significant explanatory variable for the international variation in lymphoid and total leukemia in these analyses. The calorie-leukemia association was stronger among males than among females. No significant association was observed between myeloid leukemia and any of the dietary variables studied, after adjusting for height and gross national product. CONCLUSION: The findings from this rigorous analysis of international data strengthen and expand the hypothesis based on previous simple correlation analyses and animal experiments that an underlying biological relationship exists between diet, particularly energy intake, and international variations in the incidence of certain types of human leukemia. Possible mechanisms for the calorie-leukemia associations are discussed.

Marked resistance of normal subjects to tube-feeding-induced diarrhea: the role of magnesium.

The tolerance of healthy subjects to increasing rates of tube feeding was studied to better understand the etiology of diarrhea among tube-fed patients. Five volunteers were fed Osmolite HN by continuous duodenal infusion beginning at 314 kJ (75 kcal).kg body wt-1 x d-1 and progressing each 24 h until no longer tolerated. The five subjects were able to tolerate maximum 24-h infusions of 331-511 kJ.kg-1 x d-1 (198-340 mL/h). Diarrhea developed in only three subjects. Compared with nondiarrheal stools, the high-speed supernatant of the diarrheal stools had significantly higher concentrations of magnesium (192 +/- 22 mmol/L vs 139 +/- 17 mmol/L, P = 0.005), lower concentrations of potassium and phosphorus, and similar concentrations of calcium. The mean carbohydrate, fat, and nitrogen contents were not significantly different. We conclude that normal adult males are remarkably tolerant to duodenal infusion of this typical, isotonic tube-feeding product. The diarrhea that occurred in three of the volunteers at very high infusion rates appeared to be osmotic and attributable predominantly to magnesium.

Immune suppression after acute ethanol ingestion and thermal injury.

Acute alcohol ingestion is commonly associated with burn injury. Both alcohol ingestion and burn injury produce immune suppression, but the combination of these factors on immune function has not been investigated. To study this combined effect, immune function was measured in rats with a 30% burn injury following a single ingestion of 2.4 g/kg of ethanol (EtOH) and compared to that of animals with burn injury only, animals with EtOH only, and animals with neither alcohol nor burn injury. Four days after ethanol and/or burn, animals receiving both ethanol and burn injury had significant suppression of in vivo chemotaxis and lymphocyte responsiveness to lipopolysaccharide (LPS) compared to animals receiving either burn injury alone or EtOH alone (P less than 0.05). There was no difference in responsiveness to concanavalin A (Con A). Serum corticosterone was significantly elevated by burn injury but not EtOH ingestion. EtOH treatment prior to injury caused a further increase in corticosterone level that was significantly associated with a decrease in immune function. These results indicate that a single EtOH exposure prior to burn injury produces greater immune suppression than does burn injury alone. This further decrease in immune function may contribute to increased susceptibility to infection and increased mortality in burn patients with acute EtOH ingestion.

Pharmacokinetics of ethanol in the guinea pig.

Chronic consumption of ethanol by pregnant and nonpregnant guinea pigs for 8 weeks at doses of 1.2 or 1.6 g/kg body weight twice daily affected pregnancy outcome and changed the pharmacokinetics of ethanol elimination. Ethanol treatment as compared to that of isocaloric sucrose decreased maternal weight, and decreased both the litter size and the number of liveborn offspring. Total litter weight was significantly decreased with the low ethanol dose (12% alcohol-derived energy). During pregnancy, low and high doses produced peak blood ethanol concentrations (BEC) of 89 +/- 8 mg/dl (mean +/- SE) and 125 +/- 6 mg/dl, respectively. At the high dose, peak BEC decreased dramatically (about 30%) in both pregnant and nonpregnant animals from treatment weeks 0 to 4; thereafter peak BEC remained depressed up to 8 weeks of treatment, which occurred with a concomitant increased volume of ethanol distribution. With both doses, rates of ethanol elimination and Michaelis-Menten's Vm values were significantly lower among pregnant as compared with nonpregnant guinea pigs during 8 weeks of treatment. These data suggest that the guinea pigs can be a valuable animal model to study the effects of low ethanol doses on fetal growth, the adaptation of peak BEC with duration of treatment and the lower rate of ethanol elimination in pregnancy.

Effects of dietary protein and ethanol intake on pregnant beagles fed purified diets.

Maternal weight gain of beagles was approximately 50% lower when ethanol was given twice daily at a dose of 1.8 g/kg body weight with either control protein (17% energy from protein) or low protein (8.5%) diet as compared to isocalorically sucrose-treated animals. Similarly, pup birth weights were about 27% lower from beagles given ethanol with either diet when compared to those from sucrose-treated bitches. Two weeks after beginning ethanol treatment, pregnant bitches fed either diet had higher hematocrit values and lower plasma concentrations of albumin and calcium as compared to sucrose-treated animals. Low dietary protein treatment, rather than ethanol, lowered maternal concentrations of red blood cell folate during pregnancy. As compared to sucrose-treated bitches, ethanol prevented folate levels in red blood cells from returning to the normal range by the 9th wk of pregnancy in animals fed low dietary protein. These data show that ethanol consumption and low dietary protein intake, independently of each other, significantly depress maternal weight gain, pup birth weight and some nutritionally related parameters of the mother.

Effects of caloric restriction and weight loss on glycemic control, insulin release and resistance, and atherosclerotic risk in obese patients with type II diabetes mellitus.

This study was designed to determine: (1) the effectiveness and safety of protein-sparing fast and gastric bypass surgery for achieving weight reduction in obese patients with type II diabetes mellitus (non-insulin-dependent diabetes mellitus); (2) the effects of these interventions on glycemic control; (3) the effects of weight loss on insulin secretion and action; and (4) the effects of treatment on atherosclerotic risk factors. Six patients consumed only a protein supplement (1.4 g/kg ideal body weight) for up to six months until a final weight below 120 percent of ideal body weight was achieved or weight loss ceased. Six patients underwent gastric bypass surgery. Both groups of patients were studied before and after treatment while consuming a balanced weight-maintaining diet. Both protein-sparing fast and gastric bypass surgery were safe and successful in the short term in producing weight loss. Both treatments improved glycemic control. Mean fasting plasma glucose values fell from 287 to 168 mg/dl (p less than 0.01). Mean total glycosylated hemoglobin values declined from 11.9 to 8.2 percent (p less than 0.01) (normal reference interval 5.85 to 8.85 percent). Patients who achieved a final weight below 125 percent of ideal body weight had significantly better post-treatment fasting plasma glucose values (130 versus 196 mg/dl, p less than 0.05) and total glycosylated hemoglobin values (6.8 versus 9.0, p less than 0.02) than those whose weight remained above 125 percent of ideal. In diet-treated patients, improved glycemic control occurred with caloric restriction alone prior to significant weight loss. Improved glycemic control was accompanied by decreased insulin resistance. Mean steady-state plasma glucose values fell from 377 to 208 mg/dl (p less than 0.008), and mean fasting insulin values fell from 31.0 to 17.0 microU/ml (p less than 0.004). Acute-phase insulin release, which was markedly impaired before treatment, did not improve even in patients who had post-treatment fasting plasma glucose values below 130 mg/dl. Significant improvements in atherosclerotic risk factors occurred. Mean high-density lipoprotein cholesterol values increased from 33.8 to 40.5 mg/dl (0.006 less than p less than 0.008), and factor VIII coagulant activity decreased from 194 to 140 percent (p less than 0.005). Serum fibrinogen also decreased (393 to 347 mg/dl, p = 0.08), although the decrease did not reach clinical significance.(ABSTRACT TRUNCATED AT 400 WORDS)

Relationship of serum immunoreactive somatomedin-C to dietary protein and energy in growing rats.

Protein-energy undernutrition has its most devastating consequences during growth. Postal somatic growth now appears to be regulated in large part by the somatomedins, a family of growth hormone-dependent peptide mitogens. This study, using growing rats as the model, was designed to determine the relationship between protein and energy intake and serum immunoreactive somatomedin-C. Four-week-old male Sprague-Dawley rats were fed ad libitum three levels of isoenergetic protein diets (5%, 10%, and 15% lactalbumin) at each of three levels of energy (ad libitum, 75% or 50% of ad libitum quantities). Dietary fat was held constant at 11.9% as cottonseed oil. At 5 weeks of age, serum somatomedin-C concentration was predominately influenced by the dietary protein and increased linearly as protein intake increased from 5% to 15%. at 6, 9, and 12 weeks of age, serum somatomedin-C concentration was influenced by both protein and energy intake, although protein intake appeared to be the more important variable. Serum somatomedin-C was highly correlated with both body weight (r = 0.84, P less than 0.001) and tail length (r = 0.74, P less than 0.01). These results indicate that measurement of immunoreactive somatomedin-C provides a valuable biochemical index of protein-energy nutriture.

Serum vitamin A (retinol) and cancer incidence in Evans County, Georgia.

A total community sample of 3,102 individuals from Evans County, Georgia, was followed for 12-14 years. During this period, 129 documented new cases of cancer were ascertained from medical records and death certificates. Cases were considered for inclusion only if documented at least 12 months after subjects were inducted into the cohort study. Cases were classified as definite, probable, and possible by strict criteria. Blood samples were drawn at the beginning of the study in 1960-62 and sera were frozen. Serum vitamin A (retinol) levels were measured in 1976 on the stored sera of 85 cancer patients and for 174 age-, race-, and sex-matched controls. Retinol estimations were performed by a fluorometric method after alumina column separation. Experiments conducted to simulate the exposure to light, thawing, and refreezing that sera may have undergone during the 14-16 years of storage showed retinol to be quite stable in response to these possible insults. As compared to controls, persons that eventually developed cancer had significantly lower mean serum retinol levels at least 12 months before the cancer diagnosis. The association was in the same direction for all 4 race-sex groups, although stronger overall for males than females, and was consistent for the various cancer sites and cell types. Both matched and regression residual analyses were used to control for the confounding variables considered: age, race, sex, obesity, social class, and smoking.

Medical evaluation of the special supplemental food program for women, infants, and children.

The special supplemental food program for women, infants, and children administered by the United States Department of Agriculture, was evaluated nationally. Participating infants, children under 4 years old, and pregnant and nursing women were investigated initially, and after receiving food supplements. The supplements were iron-fortified infant formula, iron-fortified infant cereals, and fruit juices for the infants, and milk, cheese, iron-fortified cereals, eggs, and fruit juices for the children and women. Initially, the average birth weight was lower and the infant mortality rate was higher than expected in a well nourished population. There was also evidence of slight growth retardation, a high anemia rate, and a high percentage of participants having saturation of transferrin values less 15%. The program had no effect on the prevalence of unsatisfactory values for saturation of transferrin. There was an increase in weight gain during pregnancy, and increase in birth weight, an acceleration of growth, and a reduction in the anemia rate in all participant categories except women in the first and second trimesters of pregnancy.

Diet-hormone interrelationships in the rat.

Twenty-eight-day old male rats were fed, either ad libitum or in restricted amounts, isoenergetic diets containing 2, 5, 10, 15, 25, or 50% lactalbumin and 5, 11.9, or 21.1% fat for 8 weeks. They were then killed and the plasma levels of triiodothyronine (T3), thyroxine (T4), insulin, glucagon, corticosterone, norepinephrine (NE), and epinephrine (E) were measured. Dietary changes explained most of the variation in the plasma concentrations of T3, T4, insulin, and glucagon but less than 20% of the variation in the plasma concentrations of the adrenal hormones. Dietary protein level was directly related to plasma T4, insulin and corticosterone and inversely related to plasma T3, glucagon, NE, and E. Dietary fat level had its most significant effect on the plasma glucagon concentration to which it was inversely related whereas the most noteworthy effect of a low energy intake was to reduce plasma E and thereby to increase the NE/E ratio. A refeeding study confirmed the effects of dietary protein level on plasma hormone concentrations and showed that the changes in diet-hormone interrelationships in 12-week old male rats have been derived by multiple regression analyses of the data.

Influence of diet on growth in the rat.

Twenty-eight-day old male Sprague Dawley rats were fed, either ad libitum or in restricted amounts, isoenergetic diets containing 2%, 5%, 10%, 15%, 25%, or 50% lactalbumin protein and 5%, 11.9%, or 21.1% fat for 8 weeks and were then killed. Weekly food consumption and body weight, terminal weight, body water and lipid, and liver weight, DNA, RNA, protein, and lipid were measured. The growth rate increased progressively with each increase in the level of dietary protein up to 25% protein and then declined. Growth was also accelerated by a high fat diet but was retarded by restriction of energy intake. Total body lipid correlated directly with the level of fat in the diet. Multiple regression analysis of the type: Y = beta0 + beta1X1 + beta2X2 + B3X3 + B4X4 where Y = rate of weight gain X1 = dietary protein level, X2 = protein efficiency ratio, X3 = appetite factor, and X4 = energy/protein ratio, showed that the maximum rate of weight gain of 58.8 g/week occurred when the diet contained 23% protein. Growth rate declined when the diet contained a higher protein level.

Effects od dietary protein, fat and energy on blood hemoglobin and hematocrit in the rat.

Twenty-eight-day old male Sprague-Dawley rats were fed diets containing varying levels of protein, fat and energy for 8 weeks and were killed. Blood hemoglobin and hematocrit measured at the time of killing increased progressively with increases in the level of dietary protein up to 50% protein. The Mean Corpuscular Hemoglobin Concentration (MCHC; hemoglobin concentration in g/100 ml red blood corpuscles) reached a plateau in rats fed diets containing 15% protein or more. Rats consuming low (5%) and high (21.1%) fat diets had lower hemoglobin concentration and hematocrit than rats fed the diets with intermediate fat content (11.9%); the level of dietary fat had no effect on the MCHC. Rats fed restricted amounts of diet had similar hemoglobin concentration to rats fed the same diet ad libitum; however the restricted rats had a lower hematocrit and hence a relative elevation of the MCHC.