Search

Dietary intake of selenium has been implicated in a wide range of health issues, including aging, heart disease and cancer. Selenium deficiency, which can reduce selenoprotein levels, has been associated with several striated muscle pathologies. To investigate the role of selenoproteins in skeletal muscle biology, we used a transgenic mouse (referred to as [i.sup.6][A.sup.-]) that has reduced levels of selenoproteins due to the introduction and expression of a dominantly acting mutant form of selenocysteine transfer RNA (tRN[A.sup.[Ser]sec]). As a consequence, each organ contains reduced levels of most selenoproteins, yet these mice are normal with regard to fertility, overall health, behavior and blood chemistries. In the present study, although skeletal muscles from [i.sup.6][A.sup.-] mice were phenotypically indistinguishable from those of wild-type mice, plantaris muscles were ~50% heavier after synergist ablation, a model of exercise overload. Like muscle in wild-type mice, the enhanced growth in the [i.sup.6][A.sup.-] mice was completely blocked by inhibition of the mammalian target of rapamycin (mTOR) pathway. Muscles of transgenic mice exhibited increased site-specific phosphorylation on both Akt and p70 ribosomal S6 kinase ([p70.sup.S6k]) (P- KEY WORDS: * selenium * Akt/PKB * transgenic * signaling * p70 ribosomal S6 kinase

Consumption of lycopene, the predominant carotenoid in tomatoes and tomato products, is associated with reduced prostate cancer risk. The purpose of this study was to measure the pharmacokinetics and tissue distribution of lycopene after oral administration to male dogs. After single doses of 10, 30 and 50 mg/kg body weight (BW) lycopene to 2 dogs/dose, the mean half-life was 36 h and the plasma systemic exposure levels (AU[C.sub.0-[infinity]], area under the curve) after the 30 and 50 mg/kg BW doses were similar. In a repeat dose study, 30 mg/(kg BW * d) administered orally to six dogs for 28 d resulted in steady-state plasma concentrations between 785 and 997 nmol/L lycopene. Apparent clearance, volume of distribution and apparent elimination half-life were 2.29 L/(h * kg), 96 L/kg and 30.5 h, respectively. Dogs were killed 1 or 5 d after the last dose and 23 tissues were collected for lycopene analysis. Lycopene concentrations were highest in liver, adrenals, spleen, lymph nodes and intestinal tissues. Liver lycopene concentrations were 66 and 91 nmol/g 1 and 5 d after cessation of treatment, respectively. Prostate lycopene concentrations were < 0.2 nmol/g both 1 and 5 d after dosing ceased ( KEY WORDS: * carotenoid * prostate * cancer * chemoprevention * canine

Serum concentrations of several nutrients were measured in 12 captive wild felid species including caracal (Felis caracal), cheetah (Acinonyx jubatus), cougar (Fells concolor), fishing cat (Fells viverrinus), leopard (Panthera pardus), lion (Panthera leo), ocelot (Fells pardalis), pallas cat (Fells manul), sand cat (Fells margarita), serval (Felis serval), snow leopard (Panthera uncia) and tiger (Panthera tigris). Diet information was collected for these animals from each participating zoo (Brookfield Zoo, Fort Worth Zoo, Lincoln Park Zoological Gardens and North Carolina Zoological Park). The nutritional composition of the diets at each institution met the probable dietary requirements for each species except for the pallas cat. Blood samples were collected from each animal (n = 69) and analyzed for lipids (total cholesterol, triacylglycerides, HDL cholesterol and LDL cholesterol), vitamin D metabolites [25-hydroxycholecalciferol (25(OH)D) and 1,25-dihydroxycholecalciferol (1,25(OH)2D)], vitamin A (retinol, retinyl stearate and retinyl palmitate), vitamin E ([alpha]- and [gamma]-tocopherol) and selected carotenoids. Species differences were found for all except triacylglycerides and 1,25(OH)2D. Genus differences were found for retinol, retinyl palmitate, retinyl stearate, [gamma]-tocopherol and [beta]-carotene. Circulating nutrient concentrations for many of the species in this study have not been reported previously and most have not been compared with the animals' dietary intakes. The large number of animals analyzed provides a substantial base for comparing the serum nutrient concentrations of healthy animals, for both wild and captive exotic species. KEY WORDS: * Fells * lipids * vitamin A * vitamin D * vitamin E

Age-related macular degeneration (ARMD) is inversely associated with the accumulation of lutein + zeaxanthin in the macula, but higher lutein intakes are inconsistently related to reduced risk of ARMD in epidemiologic studies. Resolution of efficacy awaits clinical trials designed with knowledge of lutein supplement pharmacokinetics. Lutein bioavailability was determined for lutein diester and unesterified lutein formulations as they might be incorporated into dietary supplements. Healthy subjects (n = 18) consumed a single dose of each formulation (either 0.5 or 0.67 [micro]mol lutein/kg body, 10 and 8 subjects, respectively) in random order, and the appearance of free lutein + zeaxanthin was measured in serum from 0 to 408 h. Areas under the serum concentration x time curves (AUC), as a measure of bioavailability, were independent of gender, body mass index and lutein dose. The lutein diester formulation was 61.6% more bioavailable than the unesterified lutein formulation with higher mean AUC, maximum serum concentration and ascending slope (P < 0.05). The AUC was greater in 14 of 18 subjects when they consumed the lutein diester formulation. Comparison with data from previous studies suggested that dissolution was a greater limitation to bioavailability than lutein ester hydrolysis because an oil-solubilized unesterified lutein preparation, given at 0.5 [micro]mol/kg body, resulted in greater mean peak concentrations and AUC compared with either the unesterified or lutein diester formulations used in our study. In conclusion, the lutein diester formulation poses no impediment to lutein bioavailability at the doses tested, but formulation dissolution is an important factor in lutein bioavailability and should be evaluated before a supplement and dose are selected for use in clinical trials. J. Nutr. 132: 3668-3673, 2002. KEY WORDS: * lutein * lutein ester * bioavailability * humans

Reactive oxygen species (ROS) are constantly produced in human beings under normal circumstances. Antioxidant systems help defend the body against ROS but may be overwhelmed during periods of oxidative stress, which can cause lipid peroxidation, damage to DNA, and cell death. Critical illness, such as sepsis or adult respiratory distress syndrome, can drastically increase the production of ROS and lead to oxidative stress. Sources of oxidative stress during critical illness include activation of the phagocytic cells of the immune system (the respiratory burst), the production of nitric oxide by the vascular endothelium, the release of iron and copper ions and metalloproteins, and the vascular damage caused by ischemia reperfusion. Only indirect measurements of ROS are available, but the presence of oxidative stress in critical illness is supported by clinical studies. In general, serum antioxidant vitamin concentrations seem to decrease and measures of oxidative stress seem to increase in critically ill populations. Oxidative stress has been associated with sepsis, shock, a need for mechanical ventilation, organ dysfunction, acute respiratory distress syndrome, disseminated intravascular coagulation, surgery, and the presence of an acute-phase response. In addition, higher levels of oxidative stress seem to occur in patients with more notable injuries. Dietary supplementation with antioxidant vitamins seems to be the logical answer to decreasing serum antioxidant concentrations, but antioxidants may have adverse effects. The benefit of supplementing antioxidants in critically ill populations has not been shown and requires further study., The cellular metabolism of oxygen in human beings continuously produces small amounts of reactive oxygen species (ROS). Tissue damage, whether from trauma, ischemia, or infection, leads to the increased production [...]

Objective This study compared distributions of carotenoid intake and diet-serum correlations using two sources of carotenoid data: the US Department of Agriculture-National Cancer Institute (USDA-NCI) carotenoid food composition database and values accompanying the Block-NCI Health Habits and History Questionnaire (HHHQ). Design and subjects A 100-item food frequency questionnaire was used to collect dietary data from 2,152 adults, aged 43 to 85 years, who were participating in the Nutritional Factors in Eye Disease Study, a population-based study designed to evaluate nutritional factors associated with age-related eye disease. Blood samples were collected from a random sample of 400 nonfasting participants in the study. Results Median carotenoid intakes using HHHQ vs USDA-NCI data were alpha carotene (229 vs 223 [µgram]/day), beta carotene (1,321 vs 1,325 [µgram]/day), beta cryptoxanthin (72 vs 21 [µgram]/day), lutein + zeaxanthin (653 vs 811 [µgram]/day), and lycopene (593 vs 1,615 [µgram]/day). All paired differences in carotenoid intake were significantly different from zero (Wilcoxon signed-rank, P < .0001). Despite these differences, the two databases similarly ranked individuals according to carotenoid intake: Spearman correlations ranged from .71 (lycopene) to .93 (alpha carotene). Differences between diet-serum correlations (adjusted for energy, body mass index, high density lipoprotein, and total cholesterol) using HHHQ vs USDA-NCI data were minor and not significant (P > .05): alpha carotene (r=.33 vs .32), beta carotene (r=.27 vs .32), beta cryptoxanthin (r=.48 vs .53), lutein + zeaxanthin (r=.28 vs .24), and lycopene (r=.29 vs .25). Conclusions Although estimates of carotenoid intake differed significantly, only minor differences in carotenoid rankings and diet-serum correlations were observed using either data source in this population. J Am Diet Assoc. 1996; 96: 1271-1275, Carotenoids are brightly colored, fat-soluble plant pigments that are introduced into human beings and animals through the consumption of fruits and vegetables. Growing interest in the potential biological importance of [...]

Under normal circumstances, free radicals that are produced through biological processes and in response to exogenous stimuli are controlled by various enzymes and antioxidants in the body. Laboratory evidence suggests that oxidative stress, which occurs when free radical formation exceeds the ability to protect against them, may form the biological basis of several acute medical problems, such as tissue injury after trauma, and chronic conditions, such as atherosclerosis and cancer. A potential role for the antioxidant micronutrients (vitamin C, vitamin E, and the carotenoids) in modifying the risk for conditions that may result from oxidative stress has stimulated intense research efforts, increased interest in micronutrient supplements, and heightened consumer interest in these compounds. Much remains to be learned, however, about the bioavailability, tissue uptake, metabolism, and biological activities of these micronutrients. These biological characteristics will ultimately determine their clinical usefulness in modulating oxidative stress. Also, whether the antioxidant mechanism explains their relationship with risk for acute and chronic disease in epidemiologic studies remains to be determined. Increased knowledge in this area of nutrition science will have an impact on both clinical dietetics practice and public health nutrition guidelines. J Am Diet Assoc. 1996; 96:693-702., Because of characteristics of their chemical structures, vitamin C and vitamin E both function as antioxidants in various biochemical reactions: Historically, carotenoids have been recognized as vitamin A precursors, but [...]

We examined the concentrations of five carotenoids in the serum and diet of a population-based sample of 400 individuals to determine what physiologic and lifestyle factors were related to serum carotenoid concentrations, how these relationships differed among the carotenoids, and if these relationships reflected differences in carotenoid intake. Lower serum concentrations of [Alpha]-carotene, [Beta]-carotene, [Beta]-cryptoxanthin, and lutein + zeaxanthin generally were associated with male gender, smoking, younger age, lower non-HDL cholesterol, greater ethanol consumption and higher body mass index. Serum lycopene generally was not related to these factors, but lower lycopene levels were associated with older age and lower non-HDL cholesterol. Only the hydrocarbon carotenoids ([Alpha]- and [Beta]carotene and lycopene) were directly associated with HDL cholesterol. The associations of some factors (gender, age, smoking, and ethanol intake) with serum carotenoids were similar to the associations of these factors with levels in the diet, indicating that serum carotenoids may reflect the influence of these factors on carotenoid intake. Consistent with this notion, correlations between serum and dietary carotenoids did not differ between smokers and nonsmokers. Other factors (HDL and non-HDL cholesterol and body mass index) associated with carotenoids in the serum were not associated with carotenoid intake, indicating that physiologic conditions that affect the absorption, storage, and utilization of carotenoids may influence these associations. These physiologic and behavioral correlates of carotenoids could explain or modify associations of carotenoids with chronic diseases. INDEXING KEY WORDS: carotenoids; humans