Effects of a diet containing different amount of vitamin E-enriched egg yolk powder on lipid peroxidation, hemolysis, and serum lipid concentration were examined in young and old rats. Young and old rats were fed experimental diets containing 5.6% or 22.5% of normal egg yolk powder, and 5.6% or 22.5% of vitamin E-enriched egg yolk powder. When young rats were fed these diets, their tocopherol concentrations in testes, heart, kidneys, and retroperitoneum fat pads increased according to the diet tocopherol contents. Lipid peroxide levels in these tissues were inversely proportional to the tocopherol concentrations. The liver and serum, however, did not show the above relationship. In the rats fed vitamin E-enriched egg yolk diets hemolysis did not increase, in contrast to those fed normal egg yolk diets. The rats fed a 5.6% vitamin E-enriched egg yolk diet had a lower serum cholesterol level than those fed a normal egg yolk diet. In old rats, one control group was used to determine initial tocopherol concentration and two other groups were fed 5.6% normal and vitamin E-enriched egg yolk diets. The vitamin E-enriched egg yolk rats showed lower weights of the body, liver, and retroperitoneum fat pads at the end of the experiment. The normal egg yolk group had atrophied testes. The tissue and serum tocopherol concentrations were increased in the vitamin E-enriched egg yolk group, whereas they were decreased in the normal egg yolk group. In the vitamin E-enriched egg yolk group, lipid peroxide, hemolysis and serum cholesterol, especially HDL-cholesterol, did not increase. These results indicate that egg yolk tocopherol was absorbed and prevented lipid peroxidation and hemolysis in young and old rats, and testes atrophy in old rats.

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The preventive effect of dimethyl-β-propiothetin (DMPT) and methylmethionine at 5 mM each on stress-induced gastric ulcers in rats was compared. Gastric ulcer-diseased rats were induced by the water immersion method. The ulcer index of test rats in the DMPT group was noticeably lower, compared with those in the methylmethionine and the control groups. A comparison of the activities of serum transaminases and amylase, and the amounts of various blood components in test rats claimed that the DMPT group rats were most resistive to such strain compared with the control and the methylmethionine group rats. These results indicate that DMPT is a potent preventive-agent against the stress-induced gastric ulcers in rats without any side effects.

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The effect of dietary vitamin A on the toxicity of 2, 3, 7, 8tetrachlorodibenzo-p-dioxin (TCDD) and the effect of TCDD on the tissue vitamin A levels in 8-week-old male Sprague-Dawley rats of variable vitamin A status, were investigated. Rats were fed purified casein based diets containing 2, 000, 5, 000, 8, 000, or 21, 000 IU of vitamin A/kg from weaning and throughout the experiment. The study was terminated 44 days after the administration of a single oral dose of 0, 15, 30, 60, or 120μg TCDD/kg body wt. With this dietary regimen it was possible to obtain healthy animals of the same age with a vitamin A status that varied within a physiological range. LD₅₀-values for TCDD could not be calculated in any dietary group due to the unexpectedly low mortality rate. The obtained data, however, suggest that low dietary intake of vitamin A impairs the ability to tolerate the lethal effect of TCDD and/or decreases the survival time. Some TCDD-related effects, i.e. body weight loss, liver enlargement and decreased testes weight, were more pronounced in the groups receiving low levels of dietary vitamin A, whereas the decrease in thymus weight was as severe in all dietary groups. Exposure to TCDD had a pronounced effect on tissue vitamin A contents. The effect differed between tissues and was dependent upon the dose of TCDD and on the vitamin A status of the animal. Generally, exposure to TCDD results in the reduction of vitamin A in most organs; very likely because the capacity for vitamin A storage is diminished. The kidney is an exception because it accumulates vitamin A in response either to TCDD itself or to the altered vitamin A status which TCDD induces. Data presented in this study are not sufficient to conclude if the observed changes of tissue vitamin A contents are sufficient to explain the spectrum of morphological changes, which is typical of TODD exposure.

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Pyruvate dehydrogenase was separated from pig heart pyruvate dehydrogenase complex by gel-permeation chromatography on a TSK G4000SWG column in the presence of 4M urea, followed by chromatography on a calcium phosphate gel-cellulose column. The pyruvate dehydrogenase was further separated into two nonidentical subunits, α and β, by high-performance liquid chromatography on a Synchropak CM-300 column in the presence of 8 M urea. The complete amino acid sequences of two subunits of pyruvate dehydrogenase were determined. The peptide fragments of S-carboxymethylated subunits were generated by treatment with endoproteinase Lys-C, endoproteinase Asp-N, trypsin, and cyanogen bromide. The subunits α and β contain 361 amino acid residues (M_r 40, 294) and 329 residues (M_r 35, 787), respectively. The amino acid sequences of subunits α and β in the pig were, respectively, 98 and 96% identical to those in humans. Hydropathy analysis and prediction of the secondary structure of two subunits suggest that the subunit α contains the thiamin pyrophosphate-binding domain and that the subunit β contains segments with a high hydrophobicity.

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In Saccharomyces uvarum, the effect of metabolic intermediates of the tryptophan-NAD pathway on the niacin-production was investigated. Exogenously added kynurenine and 3-hydroxyanthranilic acid raised the content of total niacin of the cells 2-fold as compared to the control cells, although anthranilic acid and tryptophan were less effective. Tryptophan was taken up into the cells faster than kynurenine, and the intracellular pool of tryptophan was larger than that of kynurenine. Of kynurenine (0.05mM) added to the medium, 55% went through the transaminase flux (2-H liberation), 20% through the kynureninase flux, but none through the acetyl-CoA flux. As for tryptophan, only 2% went through the kynureninase flux. The products through the transaminase flux were identified as kynurenic acid (85%) and xanthurenic acid. 3-Hydroxykynurenine, 3-hydroxyanthranilic acid, quinolinic acid and niacin were also detected. The metabolism of tryptophan via the kynureninase flux reached a plateau above 0.05mM. The production of kynurenine and kynurenic acid gradually increased above 0.05mM. Tryptophol was formed in parallel with the amount of tryptophan consumed, while the rate of niacin production increased after glucose and tryptophan were exhausted. Based on the data obtained, a possible regulatory mechanism of the tryptophan-NAD pathway was discussed.

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To study how the metabolism of N-nitrosodimethylamine (NDMA) is affected by dietary protein level and chronic ethanol feeding, 24 rabbits at 18 weeks of age, assigned to four groups, each with 6 rabbits, were fed for 8 weeks on the following 4 different diets; 21% protein content containing 21.1% casein and water, 21% protein content containing 21.1% casein and 7.5% ethanol, 7% protein content containing 4.8% casein and water, 7% protein content containing 4.8% casein and 7.5% ethanol. Body weights, liver weights and microsomal protein contents in the liver were significantly smaller in 7% protein diet groups than in 21% protein diet groups. Microsomal P-450 contents per protein content were less in 7% protein diet groups than in 21% protein diet groups. NDMA demethylation activity due to non-arachidonic acid stimulated system (NASS) and NDMA denitrosation activity were greater in 21% protein diet groups than in 7% diet groups. Chronic ethanol feeding increased NDMA denitrosation activity due to arachidonic acid stimulated system in both dietary protein levels. The ratio of NDMA demethylation activity (carcinogenic action) to NDMA denitrosation activity (detoxication action) was greater in 7% dietary protein groups than 21% dietary protein groups. The value of this ratio was decreased by chronic ethanol feeding in 7% dietary protein groups. Cytotoxic and carcinogenic actions of NDMA might be enhanced by low protein diet due to inhibition of denitrosation of NDMA in liver microsome and chronic 7.5% ethanol feeding alleviates metabolic activation of NDMA to carcinogenic compounds.

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This study described the relationship between the concentration of the branched-chain fatty acid (BCFA) in rat skin surface lipid and the serum level of the branched-chain amino acid (BCAA) and branched-chain a-keto acid (BCKA). The concentrations of the BCFAs in the monoester fraction of the skin surface lipid, and BCAAs and BCKAs in the serum were analyzed in rats fed varying amounts of protein (0 to 40%) and different types of BCAAs (3%) for 2 weeks. The serum concentrations of BCAA were proportional to the protein level by day 10 of the feeding period. This dose response was not sustained by day 14 at the end of the feeding. Protein level dependence was not so evident in the concentration of BCKA. The concentrations of BCFA, even carbon number iso-acid in particular, increased in linear proportion to protein intake in the skin surface lipid. Supplementation of valine and isoleucine to the diet at a 3% level specifically raised the concentration of the respective BCAA and corresponding BCKA in serum, and related BCFA in the skin surface lipid. Addition of leucine, however, did not affect the related BCFA concentration in spite of elevated concentration of leucine and its α-keto acid. A good linear correlation between the average concentration of the substrates in the circulation and the concentrations of the product BCFA on the skin surface was thus obtained for valine, isoleucine and their respective α-keto acid. This relationship did not appear to hold up for leucine and its a-keto acid.

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Agemaki (Sinonovacula constricta) is an edible and popular shellfish in the western part of Japan. The present study demonstrated the effects of feeding Agemaki on cholesterol and triglyceride concentrations in mice plasma and liver. Mice were fed a diet containing 0.1 % cholesterol and 0.1% Na-cholate for 1 week, and then a cholesterol-free diet or a cholesterol-enriched one for 2 weeks. To both diets, freeze-dried Agemaki was added at a 5 % level. There was no statistically significant effect on the body-weight gain, food intake, and liver weight by feeding Agemaki in both dietary regimens. However, Agemaki significantly lowered the concentrations of plasma and liver cholesterol and also of plasma triglyceride in mice feeding on the cholesterol-rich diet. A similar tendency was also observed for the mice feeding on the cholesterol-free diet. The analysis of freeze-dried Agemaki revealed a relatively larger proportion of n-3 polyunsaturated fatty acids and plant sterols, which may possibly decrease plasma lipids. So far as we know, this is the first report showing hypolipidemic effect of Agemaki.

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