In order to elucidate the existence of a hydrogen bond between α-tocopherol and phospholipids in bilayer liposomes, the effects of the presence or absence of α-tocopherol or its acetate on either the permeability of liposomes to chromate ions or the fluidity of liposomes composed of the different kinds of lecithin [egg yolk phosphatidylcholine (EPC), 1-oleoyl-2-palmitoylphosphatidylcholine (OPPC), or 1-O-oleyl-2-O-palmitylphosphatidylcholine (OPPCE)] were examined. From the results obtained, it was concluded that the hydroxyl group of α-tocopherol is hydrogen bonded to the carbonyl group of a fatty acid ester in the phospholipids of bilayer liposomes in order to retain α-tocopherol molecule in the space close to the surface of membranes formed by the unsaturated fatty acid moiety of phospholipids.
To investigate the validity of using HPLC procedure with the fluorescence detection for the estimation of the pyridoxal 5'-phosphate (PLP) concentration in human blood plasma, we modified the conditions of our previous HPLC method for PLP. By changing the pH of the mobile phase (pH 5.5) and by altering the detection wavelengths in fluorescence (excitation at 322nm and emission at 417nm), both the improved sensitivity for pyridoxic acid 5'-phosphate and elimination of interfering extraneous peaks were attained. We reported the total vitamin B6 content of healthy adult volunteers obtained by this HPLC method.
Lactoferrin (LF) was isolated from human milk by serial procedures of 45% ammonium sulfate precipitation, CM Sephadex C-50 ion-exchange chromatography, Sephadex G-100 gel filtration, and Cu-affinity chromatography, in which 59Fe lactoferrin was used as the tracer. The recovery of LF from human milk was 3.3%. LF from human milk was a single component having a molecular weight of 78k on SDS-PAGE, and showed pI 8.02 by isoelectric focusing on slab gel. The LF concen-tration was measured by rocket immunoelectrophoretic assay using anti-human LF antiserum in human colostrum and milk, from 1 to 60 days after parturition (125 samples). The LF concentrations in colostrum (1-3 days of puerperium, n=35), the transitional milk (4-7 days, n=60), and mature milk (20-60 days, n=30) were 6.7±0.7, 3.7±0.1, and 2.6± 0.4 (mean±SEM) g/liter, respectively. Both the LF and total protein (TP) concentrations showed significantly inverse correlations with the days after parturition (p<0.001). The lactoferrin/total protein ratio (LF/TP) in the mature milk (16.1±1.4%) was significantly less than that in the colostrum (20.4±1.2%, p<0.05) and the transitional milk (21.4±0.9%, p<0.05). Furthermore, iron concentration (Fe) in human milk was also measured by the internal standard technique of the spiked method on atomic absorption, and the lactoferrin iron saturation (LS%) was calculated. Neither Fe nor LS% had significant difference among these three stages of the lactation. The means (n=125) of Fe and LS% were 60.6±5.4g/100ml and 11.8±1.1%, respectively. However, significant correlation was observed between LF and Fe (p<0.005) or between LF/TP and both of Fe (p<0.05) and TP (p<0.001) in the mature milk. These results suggest that the mechanism stimulating the synthesis and secretion of LF is different from those of other proteins and LF can play variable roles in iron nutrition of babies at the different stagesof lactation.
Both goldthioglucose (GTG)-treated and the genetically obese (C57BL/6J ob/ob) mice were fed semisynthetic diets containing either soy protein isolate (SPI) or casein as a protein source, or laboratory chow. In GTG-induced obese mice, the plasma cholesterol level corre-lated positively with their body weight. The level was highest in mice fed high-fat diet, and lowest in ones fed laboratory chow. No difference was observed between SPI and casein groups whether the diet was low-fat or high-fat. Thus, in the GTG-treated mice, SPI did not have a hypocho-lesterolemic effect while dietary fat had a hypercholesterolemic effect, and laboratory chow contained some component(s) which can lower the plasma cholesterol level. Both neutral and acidic steroid contents in feces of the SPI group were not different from those of the casein group, and both groups of mice excreted a smaller amount of steroids than mice fed laboratory chow. Results of essentially the same tendency were obtained with normal mice regarding the effects of SPI and casein, although the degree of hypercholesterolemia was lower in high-fat-fed normal mice than in similarly fed GTG-treated mice. These results strengthened the inverse correlation between the amount of fecal steroids and the plasma cholesterol level upon feeding various proteins, indicating that the former is one of the important factors that determine the latter. The ob/ob mice showed a marked hypercholesterolemia irrespective of the kind of diet. The amount of fecal steroids was highest in the laboratory chow group and lowest in the casein group. This indicates that some factor(s) other than fecal steroid excretion is dominantly responsible for their hyper-cholesterolemia.
The effects of a high protein diet on bone formation and calcium (Ca) metabolism were evaluated in rats using an ectopic endo-chondral bone induction model. A control diet (18% casein) or a high protein diet (18% casein+20% lactalbumin) was given to 50-day-old rats. Ten days after the feeding of the experimental diet, rats were intramuscularly implanted with demineralized bone powder (day 0). On day 14 and day 21, the implanted bone powder was harvested, and blood and urine samples were also obtained. Urinary Ca excretion was not increased on day 12-14; however, it was elevated on day 19-21 in rats fed the high protein diet compared with rats fed the control diet. The high protein diet remarkably stimulated urinary sulfate excretion in both sampling periods, which reflected dietary sulfur-containing amino acids contents. Also, rats fed the high protein diet exhibited a decrease in serum Ca concentrations. There was little difference in Ca contents and the activities of alkaline phosphatase and acid phosphatase in the implants between control group and high protein diet group on day 14 and day 21. Histological examination in the implanted demineralized bone powder on day 14 indicated only cartilage in rats fed the high protein diet in contrast to the occurrences of osteogenesis and remodeling in those fed the control diet. Retarded bone formation in rats fed the high protein diet might be owing to, in part at least, a restricted amount of Ca utilized at the stage of cartilage calcification.
This study was conducted to determine the effects of the oral administration of the beta agonist clenbuterol on body composition in growing rats reared under a high ambient temperature. Forty-three male Wistar-strain rats of 5 weeks of age were divided into 6 groups: 2 levels of ambient temperature (26 and 33°C) and 3 dose levels of clenbuterol (0, 50, and 100μg/kg diet) under each ambient temperature. All rats were raised for 7 weeks. From the 3rd week, rats in the clenbuterol-treated groups were fed a diet containing clenbuterol. Both the lipid and cholesterol content in the rat liver, and the epididymal adipose tissue weight were significantly higher in the hot environment than in the temperature environment. Body fat component was significantly higher in rats in the 33°C groups in comparison with that in rats in the 26°C groups. On the other hand, body protein component was significantly lower in the 33°C groups than in the 26°C groups. Although the administration of clenbuterol significantly decreased fat and increased protein in the 26°C groups, no particular influence of clenbuterol ad-ministration on body composition was observed in the 33°C groups.
The intestinal uptake of [14C]oxalate, [14C] glyoxylate, and [14C] glycolate are studied in brush border membrane vesicles (BBMV) isolated from vitamin A-deficient and pair-fed control rats. The data obtained indicate that oxalate and its precursors are transported across the BBMV by passive diffusion. The intestinal uptake of glyoxylate and glycolate remains unaltered in vitamin A deficiency, while uptake rate of oxalate was significantly increased (p<0.01) in vitamin A-deficient rats as compared to pairfed controls. In conclusion, the results indicate that vitamin A deficiency leads to hyperabsorption of oxalate through the gut.
The objective of the present work was to develop a for-mulation for complementary infant and child feeding employing linear programing as a mathematical model for optimization. High lysine/high tryptophan sweet corn pulp in the dehydrated form was used as the main ingredient. The restrictions imposed on the model were nutrient re-quirements, adequate protein/energy ratio and minimum cost. The for-mula derived by the computer (FC) matched the amino acid require-ments, the protein/energy ratio (NDPCal%) and was rated high in laboratory tests in terms of sensory qualities. The cost determined for this formula was competitive in relation to commercial products used for the same purpose. Formula A, which contained 5 % more sweet corn pulp and 10% less whole powdered milk, did not differ in nutritional, sensorial and functional properties from the formula FC and was chosen for the field acceptability trial because of its lower cost. Formula A had protein efficiency ratio and Biological Value similar to casein for the rat but protein digestibility and net protein utilization were statistically lower (p<0.05) for formula A than for casein. Acceptability tested on children who were 8-18 months of age ranged from 80-90%, average value 87%.
Previously we have shown that rats fed a diet containing raw peanut meal as the sole source of protein exhibited alterations in enzyme activity and composition of certain organs. To determine the effects of isolated peanut lectin on body growth and on the intestines, experiments were carried out in weanling, male, Sprague-Dawley rats fed a casein diet incorporated with purified peanut lectin at three levels, 0.004, 0.04, and 0.2% for 23 days. Body weight gain was normal with all three diets. In rats fed the 0.004 and 0.04% peanut lectin, there were no changes in any of the small intestinal mucosal parameters under study. However, in rats consuming the 0.2% peanut lectin diet, the proximal, mid, and distal third regions of the small intestines all showed marked increases in mucosal weight, protein, and DNA contents, but without altered villus morphology. Of the 3 brush border enzymes studied, namely maltase, γ-glutamyltranspeptidase, and alkaline phosphatase, none was altered in activity in any region, suggesting that microvillus integrity was normal. These results are similar to the reported actions of red kidney bean lectin on the intestines. We conclude that peanut lectin at up to 0.2% of the diet does not inhibit food intake or growth of weanling rats and is apparently trophic for all areas of the small intestines.
Previous work from this laboratory has shown mildly elevated dietary leucine to alter the rhythm of prolactin secretion and to interfere with normal estrous cycling in the intact female rat. In this study, we have determined whether these observed effects on prolactin and cycling in turn affected fertility, gestation, mammary gland development or mammary gland morphology during lactation. Groups of control and leucine-supplemented mothers were mated with tested male breeders and a daily record was kept of pup births, pup deaths and general health and development of the pups. The day after weaning, mammary tissue was removed from dams in both groups and prepared for histological examination. In light of the previous results showing estrous cycle interruption and altered prolactin secretion, we report what was a surprising lack of effect of leucine supplementation of fertility, maintenance of gestation or overall development of the mammary glands in this species. Interestingly, however, dietary leucine supplementation was found to markedly after the histological appearance of lactating mammary tissue and to cause a significant increase in the number of litters that contained notably underdeveloped pups.
Relationship among malondialdehyde (MDA), 2-thio-barbituric acid (TBA)-reactive substances (TBA-RS), and tocopherols in the oxidation of rapeseed oil was investigated. MDA was determined by a new HPLC method with chemical derivatization. When the oil was heated at 170°C, TBA-RS and MDA increased. The contents of TBA-RS were approximately 1.6 times higher than those of MDA. Correlation between the increase in formed MDA and the decrease in tocopherols was observed. When the oxidation of the oil was initiated using 2, 2'-azobis-(2, 4-dimethylvaleronitrile) at 40°C, TBA-RS dramatically increased during the initial stage and reached plateau. Thereafter, little increase was observed. The relative ratio of MDA to TBA-RS was much lower in the reaction performed at 40°C than that observed at 170°C. These results indicated that the decrease of tocopherols was accompanied by the increase of MDA but TBA-RS did not correlate with the change of tocopherols.