Effects of dietary vitamin E, C and soybean oil supplementation on antioxidant enzyme activities in liver and muscles of rats.

The effect of elevated levels of dietary vitamin E, C and a combination of vitamin E and C (E&C) with soybean oil on activities of antioxidant (AOE) enzymes important in the protection against lipid peroxidation was studied in male rats fed with vitamin C (12 mg/g), vitamin E (3.68 mg/g) or E&C (3.68 mg/kg+12 mg/g) supplemented diets for 28 days. Catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activity in liver, pectoralis major (PM) and sartorius (S) muscles was increased significantly in rats fed with dietary vitamin C, E separately, and vitamin C&E combination, except, superoxide dismutase (SOD), which showed no alterations. These results clearly indicated that vitamin E&C separately and E&C together increased AOE activity in liver, PM and S muscle of rats. However, vitamin E and C combination enhanced AOE activity more significantly and our findings suggest the possible role of vitamin C&E and their combination in reducing the risk of chronic diseases related to oxidative stress.

Tethered-bilayer lipid membranes as a support for membrane-active peptides.

An immunosensing device, comprising a lipid membrane incorporating ion channels tethered to the surface of a gold electrode, has been reported [Cornell, Braach-Maksvytis, King, Osman, Raguse, Wieczorek and Pace (1997) Nature (London) 387, 580-583]. The present article describes key steps in the assembly of the device and provides further evidence for its proposed sensing mechanism.

Effects of dietary proteins and trypsin inhibitor on growth and lipid metabolism in hamsters.

The purpose of this study was to determine trypsin inhibitor (TI) activity in sweetpotato and soy flour diets and their effects on the growth and lipid metabolism of hamsters. Male Golden Syrian hamsters were fed different types of dietary protein containing casein, soyprotein, transgenic sweetpotato plus soy flour (TSPF+SF), nontransgenic sweetpotato (NTSPF) plus soy flour (NTSPF+SF), transgenic sweetpotato (TSPF) and nontransgenic sweetpotato flour for 28 days. The TI activity was highest in TSPF+SF (19.30 TIU/mg) and NTSPF+SF (17.20 TIU/mg) diets that induced growth retardation in animals, lowest in TSPF (5.80 TIU/mg) and NTSPF (5.50 TIU/mg) diets, which did not affect the growth of the animals, and negligible in casein (<1.00 TIU/mg) and soyprotein (2.00 TIU/mg) diets. Plasma total cholesterol (TC), high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) and triglyceride (TG) concentrations were significantly higher in hamsters fed the casein diet compared to those fed the soy protein, TSPF+SF, NTSPF+SF, TSPF and NTSPF diets. A positive correlation was observed between plasma TC concentrations of hamsters and dietary methionine, lysine, leucine content and methionine/glycine ratios. Liver TC and TG concentrations of hamsters fed casein were significantly higher than those of all other diet groups. The supplementation of sweetpotato flour with soy flour increased both protein and TI activity in the diets and the lipid metabolism of hamsters were unaffected by TI activity.

Zinc bioavailability in young adult rats fed sweet potato greens containing phytic acid.

This study determined whether phytic acid in sweet potato greens influences the bioavailability of zinc in young adult rats used as models for adult humans. A control diet (AIN-93M), two AIN-93M diets with pure phytic acid (PA) at 0.2% or 0.4%, and four diets with Georgia Jet or TU-82-155 dried blanched greens at 7.5% or 15% were fed to seven groups of 7-week male Harlan-Sprague rats for 21 days. Weight gains were generally not affected by PA concentration, were lower in the rats fed with sweet potato greens than in the control rats, and were similar in the rats fed with pure PA or control diet. Feed intake utilization, as indicated by the total weight gain per total feed intake, was almost similar in the different rat groups. Bone (femur, tibia) and organ (kidney, liver, lung, spleen) weights, except the heart weights, were similar for all diet groups. Their zinc concentrations were generally not affected by PA concentration but depended on the PA source.

Consumer acceptance of vegetarian sweet potato products intended for space missions.

Sweet potato is one of the crops selected for NASA's Advanced Life Support Program for potential long-duration lunar/Mars missions. This article presents recipes of products made from sweet potato and determines the consumer acceptability of products containing from 6% to 20% sweet potato on a dry weight basis. These products were developed for use in nutritious and palatable meals for future space explorers. Sensory evaluation (appearance/color, aroma, texture, flavor/taste, and overall acceptability) studies were conducted to determine the consumer acceptability of vegetarian products made with sweet potato using panelists at NASA/Johnson Space Center in Houston, TX. None of these products including the controls, contained any ingredient of animal origin with the exception of sweet potato pie. A 9-point hedonic scale (9 being like extremely and 1 being dislike extremely) was used to evaluate 10 products and compare them to similar commercially available products used as controls. The products tested were pancakes, waffles, tortillas, bread, pie, pound cake, pasta, vegetable patties, doughnuts, and pretzels. All of the products were either liked moderately or liked slightly with the exception of the sweet potato vegetable patties, which were neither liked nor disliked. Mean comparisons of sensory scores of sweet potato recipes and their controls were accomplished by using the Student t-test. Because of their nutritional adequacy and consumer acceptability, these products are being recommended to NASA's Advanced Life Support Program for inclusion in a vegetarian menu plan designed for lunar/Mars space missions.

Sweet potato in a vegetarian menu plan for NASA's Advanced Life Support Program.

Sweet potato has been selected as one of the crops for NASA's Advanced Life Support Program. Sweet potato primarily provides carbohydrate--an important energy source, beta-carotene, and ascorbic acid to a space diet. This study focuses on menus incorporating two sets of sweet potato recipes developed at Tuskegee University. One set includes recipes for 10 vegetarian products containing fom 6% to 20% sweet potato on a dry weight basis (pancakes, waffles, tortillas, bread, pie, pound cake, pasta, vegetable patties, doughnuts, and pretzels) that have been formulated, subjected to sensory evaluation, and determined to be acceptable. These recipes and the other set of recipes, not tested organoleptically, were substituted in a 10-day vegetarian menu plan developed by the American Institute of Biological Sciences (AIBS) Kennedy Space Center Biomass Processing Technical Panel. At least one recipe containing sweet potato was included in each meal. An analysis of the nutritional quality of this menu compared to the original AIBS menu found improved beta-carotene content (p<0.05). All other nutrients, except vitamin B6, and calories were equal and in some instances greater than those listed for NASA's Controlled Ecological Life Support Systems RDA. These results suggest that sweet potato products can be used successfully in menus developed for space with the added benefit of increased nutrient value and dietary variety.

Effect of traditional processing practices on the content of total carotenoid, beta-carotene, alpha-carotene and vitamin A activity of selected Tanzanian vegetables.

The alpha-carotene, beta-carotene and total provitamin A carotenoids and the effect of traditional processing practices on the retention of these provitamins were studied using amaranth, cowpea, peanut, pumpkin and sweet potato leaves. Results of this study indicated that the content of total carotenoids, beta-carotene and alpha-carotene were in the range of 26.79-44.74 mg, 4.16-19.12 mg, and 0.99-10.26 mg per 100 g of dry vegetables, respectively. The vitamin A activities were 4.042, 3.124, 0.829, 2.025 and 1.581 mg RE per 100 g of dry amaranth, cowpea, peanut, pumpkin and sweet potato leaves, respectively. The traditional processing practices of sun drying and storage in ventilated containers resulted in a significant (p < 0.05) decrease in the concentration of total carotenoids, beta-carotene and alpha-carotene for all the vegetables. Conventional blanching and cooking resulted in a significant (p < 0.05) increase in the concentration of carotenoids in the cowpea, peanut and pumpkin leaves while in amaranth and sweet potato greens, thermal processing resulted in a significant (p < 0.05) decrease in the concentration of these nutrients.

Proximate composition and mineral content of selected Tanzanian vegetables and the effect of traditional processing on the retention of ascorbic acid, riboflavin and thiamine.

Proximate composition, mineral content and the effect of traditional processing practices on the retention of ascorbic acid, riboflavin and thiamine were studied using amaranth, cowpea, peanut, pumpkin and sweetpotato leaves. Results of this study indicated that, crude protein, crude fat, carbohydrate and ash contents were in the range of 20.64--46.56 percent, 2.57--4.34 percent, 35.43--63.50 percent and 8.92--15.69 percent respectively. The mineral content per 100 g of fresh vegetables was in the range of 83.64--229.34 mg, 145.97--780.19 mg, 11.5--2l.31 mg, 43.02--110.30 mg, 0.96--5.90 mg and 0.40--2.24 mg for Ca, K, Na, Mg, Fe and Zn respectively. For ascorbic acid, riboflavin and thiamine, concentrations in 100 g of fresh vegetables were in the range of 43.78--89.00 mg, 0.62--1.71 mg and 0.09--0.30 mg respectively. The traditional processing practices of sun/shade drying and storing in ventilated containers resulted in a significant (P <0.05) decrease in ascorbic acid, riboflavin and thiamine for all vegetables. Conventional blanching and cooking for up to 15 minutes resulted in a significant (P <0.05) increase in riboflavin content in cowpea, peanut and pumpkin greens while in amaranth and sweetpotato leaves, thermal processing resulted in a significant (P <0.05) decrease in the vitamin. Based on the results of this study, the vegetables were good dietary sources of minerals, carbohydrate and protein.

Effect of blanching on the content of antinutritional factors in selected vegetables.

The effect of blanching on the antinutritional content was studied in cabbage, turnip, collard, sweetpotato and peanut leaves. All the vegetables contained various amounts of phytic acid, tannic acid and/or oxalic acid. Tannic acid was found in largest amounts ranging from 1266.00 mg/100 g in cabbage to 491.00 mg/100 g in sweetpotato. Phytic acid content ranged from 0.31 mg/100 g in sweetpotato to 3.97 mg/100 g in collard. Oxalic acid was in trace amounts in cabbage and turnip; but high concentrations were found in sweetpotato (469.67 mg/100 g) and peanut greens (407.00 mg/100 g). Levels of both tannic acid and phytic acid were significantly (p < 0.05) reduced by conventional and microwave blanching methods while oxalic acid levels were not significantly (p < 0.05) reduced in most of the treatments by either of the blanching methods. In general, blanching is recommended as an effective method for reducing the antinutritional factors in green vegetables, however, further investigation on the heating times for both conventional and microwave blanching methods has been suggested.

Metabolic effects of infection by the stomach worm Obeliscoides cuniculi in rabbits fed diets varying in nutritive quality.

Rabbits parasitized by Obeliscoides cuniculi were used as models for stomach worm parasitism in ruminants. A 3 X 4 randomized complete block design containing three levels of of infection (NI, no infection; LI and HI, infections produced by 1,800 and 30,000 larvae, respectively) and four levels of diet (PC, high protein and carbohydrate; pc, low protein and carbohydrate; Pc, high protein, and low carbohydrate; pC, low protein and high carbohydrate) was replicated four times. Mean weight gains for rabbits on diets pc or PC were not influenced by infection level, whereas LI rabbits on diets Pc and pC gained as well as the NI animals and more than the HI ones. Only HI rabbits exhibited anorexia. NI and LI rabbits has positive feed conversion efficiencies, whereas those of HI rabbits were negative. The apparent digestibilities of organic matter, protein, and ash in rabbits with different infection levels varied with diet. Daily nitrogen balances were positive. The changes in concentrations of amino acids in the plasma typically associated with systemic, fever-producing infections or with starvation or protein-calorie malnutrition did not occur in infected rabbits. Only the high level infections produced adverse effects on productivity. These effects occurred on diets pc, Pc and pC and were mediated by anorexia.