The vitamin B₁₂ (B₁₂) content in seven species of seaweed that are consumed frequently in Hokkaido, Japan, was microbiologically measured using Escherichia coil 215. Asakusanori (Porphyra tenera), maruba-amanori (Porphyra suborbiculata) and akaba-gin-nansou (Rhodogtossum pulcherum) showed higher B₁₂ content than the other species, although the content varied greatly among samples in the same species. A bioautography on a thin-layer plate holding a mixture of silica gel and cellulose, differentiation of B₁₂ and its analogues using a binding specificity of intrinsic factor and haptocorrin, and comparison of the B₁₂ concentra tion determined by the radioisotope dilution assay method using the intrinsic factor as the B₁₂-binding protein with that by the bioassay method, predominantly showed B₁₂ in maruba-amanori and B₁₂ analogues in wakame (Undaria pinnatifida) and akaba-gin-nansou. The B₁₂ uptake of akaba-gin-nansou from artificial seawater was similar to that of asaku sanori that contained only B₁₂.

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When asakusanori was incubated in artificial seawater, it released a significant amount of vitamin B₁₂. The rate of release was very high at the beginning of incubation and steeply decreased. Four-fifths of the released B₁₂ was a macromolecule-bound form and the rest was free form, of which some were taken up by the asakusanori tissue. Asakusanori took up the free form B₁₂ from the incubation medium by concentration and temperature-dependent processes. The amount of uptake increased with the time of incubation and did not attain a plateau after 4h. The capacity was retained even after storage in frozen state for 11 months.

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The Otsuka Long-Evans Tokushima Fatty (OLETF) rat, serving as a spontaneously diabetic model with non-insulin-dependent diabetes mellitus (NIDDM), exhibits impaired glucose tolerance (IGT) at about 16 weeks of age. In this study, we investigated whether or not biotin, a water-soluble vitamin, improved the IGT of OLETF rats. To this end, we administered diets containing one of three levels of biotin, a high-biotin diet (BH), a normal-biotin diet (BN) and a basal-biotin diet (BB), to OLETF rats up to 24 weeks of age. An oral glucose tolerance test (OGTT) was performed four times between 13 and 22 weeks of age. The administration of a BH corrected the IGT of OLETF rats. Upon further investigation, we found that insulin secretion in the OLETF-BH rats was decreased to a significant extent, signaling that the hyperinsuline mia typical to the OLETF-BH rats had clearly improved. Body weights were significantly lower in the OLETF-BH group than in the other OLETF groups, even though the OLETF-BH rats showed a significantly higher average daily food intake. The body weight gain of the OLETF-BH rats followed the same tendency as the control-LETO (Long Evans Tokushima Otsuka) rats (LETO-BB and LETO-BN). These results demonstrate that a high-level biotin diet can improve the glucose handicap in NIDDM rats.

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This study was conducted to evaluate the effects of different types of dietary fibers (DF) under the conditions with or without cholesterol (Chol) loading on the amount and composition of steroids in rat feces. Rats were fed Chol-unsupplied diets containing 10% lard and 5% DF preparation isolated from four kinds of food, bamboo shoots, edible burdock, apple and corn, for three weeks. The respective diets were supplemented with 0.5% Chol and then given to the rats for a further two weeks. The excretion of total bile acid (BA) and several major BAs increased significantly in the apple group with or without Chol loading when compared with that in the cellulose (CP) or other DF groups. The tendency in the apple group was more noticeable when the diet was supplemented with Chol. This is presumably a major reason for the tendency of decrease in serum and liver Chol concentrations in the apple group. The ratio of secondary BAs to total BA in the feces was signifi-cantly low in the apple group. Although the lithocholic acid (LCA)/deoxycholic acid (DCA) ratio, a risk index for colorectal cancer, was significantly lower in the bamboo, burdock and apple groups than in the CP or corn groups when given the diet without Chol, the differences disappeared with the addition of Chol. The proportion of coprostanol, a secondary metabolite of Chol, was smaller in the former three groups than in the CP or corn groups. These results suggest that the intake of some DF by host animals works beneficially for the microbial conversion of BA and Chol in the large intestine but that the addition of Chol acts to cancel such beneficial effects.

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Rats were fed semipurified diets containing 10% fat with a constant polyunsaturated/monounsaturated/saturated fatty acid ratio of 1:1:1. This was performed by mixing vegetable oils. Linoleic acid was the sole polyunsaturated fatty acid in the linoleic acid group. The a-linolenic and arachidonic acids were contained at the 1 % level in the diet at the expense of linoleic acid in the α-linolenic acid and arachidonic acid groups, respectively. The concentration of serum triglyceride, phospholipid and liver triglyceride were significantly lower in the α-linolenic acid and arachidonic acid groups than in the linoleic acid group. Hepatic phospholipids were significantly higher in the α-linolenic acid and arachidonic acid groups as compared to the linoleic acid group. Compared to the linoleic acid group, the percentages of arachidonic acid in the phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in the liver and heart were significantly lower in the α-linolenic acid group; in contrast, they were significantly higher in the arachidonic acid group. Dietary arachidonic acid, but not α-linolenic acid, resulted in a marked reduction of linoleic acid and increased arachidonic and n-6 docosapenta-enoic acids in heart cardiolipin. Platelet thromboxane (TX) A₂ production tended to be lower in the α-linolenic acid group as compared to the linoleic acid and arachidonic acid groups. There was no difference in TXA2 production between the linoleic acid and arachidonic acid groups. The aortic production of prostacyclin (PGI₂) was the same among the three groups. The ratios of TXA₂ and PGI₂ in the linoleic acid and arachidonic acid groups were comparable, whereas they were significantly higher than that in the α-linolenic acid group. The results demonstrate that dietary arachidonic acid enriches the arachidonic acid content in tissue phospholipids more effectively than linoleic acid, whereas the effect on the production of TXA₂ and PGI₂ was comparable under these experimental conditions.

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In relation to banana ripening, banana peel was examined for carotenoid pigments by a combination of alumina column chromatography and high-performance liquid chromatography (HPLC). Carotenoids and their fatty-acid esters were first separated by an alumina column into five fractions, of which each was further subfractionated by HPLC with different kinds of solvent. The carotenoid content of the banana peel was in the range of 3-4μg per gram as lutein equivalent. The ingredients of the carotenoids were ascertained to consist of lutein, β-carotene, α-carotene, violaxanthin, auroxanthin, neoxanthin, isolutein, β-cryptoxanthin and α-cryptoxanthin. Most of the oxygenated carotenoids were found to occur in the esterified form, mainly with myristate, and to a lesser extent with laurate, palmitate or caprate.

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The effect of long-term ‘corn peptide (CP)’ ingestion on alcohol metabolism was investigated in stroke-prone spontaneously hypertensive rats (SHR-SP) with alcohol loading. Long-term CP ingestion in the EtOH/CP group did not significantly increase plasma GOT and GPT activities but markedly increased hepatic ADH and ALDH activities. Intragastric CP administration prior to a dose of 1.0g/kg ethanol significantly lowered the blood ethanol concentration in SHR-SP which had been loaded with ethanol for a long time. Compared with non-loaded SHR-SP (control group), the rats loaded for a long time with ethanol (EtOH group) showed high concentrations of taurine, glycine and histidine in the plasma. The plasma threonine and proline concentrations were significantly elevated by long-term CP ingestion (EtOH/CP group), but the plasma alanine concentration was rather decreased. These results suggest that short or long-term CP ingestion may enhance the alcohol metabolism within the body because of an increase in ADH and ALDH activities as well as the alleviation of alcohol-related hepatic injury.

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Soybeans were treated with proteases to reduce allergenicity. By immunoblotting with a monoclonal antibody against a major soybean allergen (Gly m Bd 30K), two of eight proteases so far tested were selected to achieve a reduction in allergenicity. Both antigenicity to the monoclonal antibody and allergenicity to the sera from soybeansensitive patients proved to be markedly reduced by processing with either protease. Thus, soybeans treated with an appropriate protease may possibly be supplied as a hypoallergenic foodstuff for patients.

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Hepatic cystathionine β-synthase activity was increased in rats fed a high-protein diet for three or five days as compared to rats given laboratory chow (day 0). In the low-protein diet group, the enzyme activity decreased after both feeding periods. Similar changes in the cystathionine β-synthase mRNA levels were observed in the rats fed these diets. The changes in cystathionine β-synthase activity caused by alteration of the dietary protein content were mainly due to changes in the mRNA levels.

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The effects of dietary fats consisting of different fatty acids on the content of mitochondrial uncoupling protein in the interscapular brown adipose tissue were studied in rats. Sprague-Dawley male rats were meal-fed an isoenergetic diet based on either beef tallow or safflower oil for nine weeks. The gain in body weight during the experimental period did not differ between the two dietary groups. The weight of the brown adipose tissue was similar in the two dietary groups, whereas the weight of the abdominal white adipose tissue was larger in rats fed the beef tallow diet. The content of mitochondrial uncoupling protein in brown adipose tissue was lower in the beef tallow diet group than in the safflower oil diet group without differing mitochondrial mass between the two dietary groups. These results suggest that, in rats, a beef tallow diet reduces the content of uncoupling protein in brown adipose tissue, resulting in lower diet-induced thermogenesis as compared to a safflower oil diet.

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We investigated the influence of the administration of anti-asialo GM₁ antibody on aberrant crypt foci (ACF) formation induced by a single injection of 1, 2-dimethylhydrazine (DMH). At four weeks after the injection of DMH (20mg/kg body weight), the number of ACF and aberrant crypts were counted. Most ACF appeared in the distal large bowel, accounting for approximately 60% of the total ACF in both groups. Rats administered anti-asialo GM₁ had significantly more ACF in the distal colon, the rectum and the total large bowel as compared to control rats. A similar tendency was observed for the number of aberrant crypts. The increased number of ACF resulting from the administration of anti-asialo GM₁ was not accompanied by the enlargement of ACF size in every part of the colon. This study demonstrated that the administration of anti-asialo GM₁ at the initiation stage leads to an increase in ACF as well as aberrant crypts in the distal colon, rectum and total large bowel probably via the suppression of natural killer cells.

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