[in Japanese]

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From 5 weeks of age, stroke-prone spontaneously hypertensive rats (SHRSP) were fed a diet based on Chlorella (Chlorella vulgaris E-25) and were either observed until natural death or sacrificed at 29 weeks of age in order to examine the effects of the alga on blood pressure, incidence of stroke lesions, hypertensive vascular lesions and life-span. The results were as follows: 1) Elevation of blood pressure was depressed from the start of Chlorella feeding, and after 10 weeks of age the blood pressure remained unchanged at 210 to 230mmHg. 2) The average life-span of the Chlorella diet group was remarkably longer than that of the control group. 3) In the Chlorella diet group, depression of plasma renin activity (PRA), reduction of incidence of cerebral stroke lesions, lowering of incidence of hypertensive vascular lesions in the kidneys, testes and adrenals, and depression of decrease in the elastin content in the aorta were recognized. This group also showed fewer changes in electron microscopical findings in the mesenteric arteries. These results demonstrated that the PRA of SHRSP fed the Chlorella diet was just as low as that of normotensive rats (WKY), and that the effects resulted in the inhibition of vascular lesions, and lowering of the incidence of cerebral stroke lesions, thus extending the life-span.

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The present study was carried out as part of a series of nutritional investigations on the utilization of krill, with special reference to the effects of cambining krill with soy protein isolate (SPI). Wistarstrain weanling male rats were fed on five experimental diets: 1) casein (control), 2) krill, 3) SPI, 4) SPI+krill and 5) SPI+krill+methionine. The animals were then examined for growth, changes in organ weight and serum lipid contents. The results obtained were as follow: 1) Increase in body weight was significantly reduced only in the SPI-fed group, whereas in the group fed krill combined with SPI, growth recovered to the level observed in the casein-fed group. 2) The total lipid content in the serum of the SPI-fed group was significantly higher than that of the casein-fed group. However, the combined group maintained the same lipid level as that in the casein-fed group. 3) The total cholesterol content in serum was significantly lowered in the combined (SPI+krill-fed) group in comparison with the other groups. However, addition of methionine to this group did not result in any additional lowering effect on the total cholesterol content. These results suggest that the addition of SPI is useful for the utilization of krill as a foodstuff.

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The effects of phytic acid on the digestion of casein and soybean protein with trypsin, pancreatin or pepsin were examined by determining the concentrations of amino groups released from the reaction mixture using the TNBS method. Phytic acid did not affect the proteolysis of either casein or soybean protein by trypsin or pancreatin. The disc gel electrophoretic patterns of these proteins treated with trypsin also confirmed that the presence of phytic acid did not affect the proteolysis. The addition of Ca²⁺ ion up to a concentration of 50mM slightly lowered trypsin activity in the presence or absence of phytic acid. Peptic digestivities of the proteins decreased with phytic acid concentration. The addition of Ca²⁺ ion up to a concentration of 50mM showed no effect on peptic activity in the presence or absence of phytic acid. Disc gel electrophoretic patterns indicated that the peptic digestivities of αs-and β-caseins and 7S globulin decreased with phytic acid concentration, and that the digestivity of 11S globulin was not influenced to such an extent as that of 7S globulin. The inhibition by phytic acid was considered to occur as a result of an interaction of phytic acid with the proteins, rather than with pepsm.

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Daily intakes of organophosphorus pesticides (malathion and fenitrothion) by 6 housewives living in Osaka metropolitan district were determined. Their diets were collected for 7 consecutive days using the duplicate portion method. Malathion and fenitrothion were detected in 11 and 9 samples out of 42, respectively. The mean values of daily intake of malathion and fenitrothion were 0.88μg and 0.47μg, respectively. The maximum intakes of malathion and fenitrothion were 7.72μg and 3.89μg, respectively. We also determined the intakes of malathion and fenitrothion from lunches provided on 23 consecutive days at an elementary school in D city in Osaka Prefecture. The detection frequencies of malathion and fenitrothion were 73.9% and 47.8%, respectively. The average and maximum intakes of malathion were 1.11μg and 3.58μg, respectively, while those of fenitrothion were 0.51μg and 2.92 μg, respectively. As wheat seemed to be the major source of malathion and fenitrothion in the diets, the levels of the two pesticides in wheat grain, flour and wheat products were analyzed. Of 60 samples tested, malathion (maximum value; 0.347μg/g wheat grain) and/or fenitrothion (maximum value; 0.320μg/g flour) were found in 39.

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A series of heteropalysaccharides were isolated from the delipidated cell wall fraction of Spirulina maxima, by successive extractions with cold and hot water, and then with cold and hot alkali. These polysaccharides had similar carbohydrate compositions, containing L-rhamnose as the main component, and D-galactose, D-glucose, D-mannose and D-glucuronic acid, although the proportions of these com- ponents appeared to vary according to the extraction conditions employed. Methylation and Smith degradation studies indicated that they had essentially similar structural features, containing a backbone chain of α- (1→3) -linked L-rhamnose residues, some of which were substituted with other sugar residues at the C-2 and C-4 positions. The side-chains were shown to consist of (1→3) -, and (1→4) -linked D-glucose and D-mannose residues, and (1→4) -linked D-galactose residues; most of the D-glucuronic acid residues were found to be located at the terminal ends. A highly branched glycogen-type α-D-glucan was also isolated from the water extract of the crude cell wall preparation. Methylation and gel filtration studies, involving the action of debranching enzymes, showed that the lengths of the α- (1→4) -linked unit chains of the D-glucose residues were distributed in the range of DP 3 to 14. The insoluble residues remaining after hot alkali treatment of the cell wall contained D-glucosamine and muramic acid, in addition to several kinds of amino acids, suggesting the presence of a peptidoglycan, similar to that of bacterial cell walls.

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Ogo-dofu, which is made of agar, i. e., the polysaccharides from the seaweed Gracilaria verrucosa (G. v.), and Egoneri, which is made from the polysaccharides of the seaweed Campylaephora hypnaeoides (C. h.), are types of seaweed dishes that differ slightly from Igesu-ryori, which is made from the polysaccharides of Ceramium boydenii (C. b.). In the cooking process for these dishes, the addition of extract of rice bran or vinegar is essential. The roles of these substances in the solubilization of agar were analysed by measuring the gel strength and by determining the molecular weight of polysaccharides obtained from the above seaweeds by high-performance liquid chromatography (HPLC). The addition of a 1% extract of rice bran or vinegar resulted in acceleration of agar solubilization in the case of G. v. gel. However, the addition of vinegar resulted in acceleration of agar setting in the case of C. h. gel. The molecular weight distribution of C. h. polysaccharides determined by HPLC was found to be completely different from that of G. v. polysaccharides and C. b. polysaccharides.

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The present study was undertaken in order to investigate the mechanisms responsible for the toxicity of ingested raw Kintoki and Ohfuku beans (Phaseolus vulgaris). Body weight gain in rats given diets of these raw beans was significantly lower than that in rats given these beans after steaming. The adverse effect of the raw bean diet on growth was accompanied by significant reduction in the activities of hydrolases (sucrase, alkaline phosphatase and leucine aminopeptidase) localized in the brush border membrane of the small intestine, and was not improved when the diets were supplemented with methionine. Adaptive increases in the activities of these enzymes in rats administered a 20% casein high-sucrose diet were inhibited by the addition to the diet of lectin fractions isolated from these raw beans. These results support the contention that the initial mechanisms responsible for the toxicity of ingested raw Kintoki and Ohfuku beans, as in the case of concanavalin A and winged bean lectin toxicity suggested n previous studies, involve binding of the bean lectins to the luminal surface of the small intestine, thereby disturbing the functional conformation of the brush border membrane.

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Thirty-three strains of Bacillus subtilis were isolated from commercially available “natto” preparations. These strains produced significantly different amounts of the viscous material, levan. Levan production by some strains depended on the cultivation conditions. Levan production reached a maximum after 8 days of cultivation, the optimum temperature and pH ranging from 25°C to 30°C and from 5 to 8, respectively. Sucrose was the most suitable carbon source and levan production increased in parallel with the initial sucrose concentration. The optimum biotin concentration was 10μg%. Levan was fractionated into two parts with a high and a low molecular weight. The average molecular weight of the low-molecular-weight fraction varied among strains. No difference in levan sucrase activity in the culture broth was found among strains.

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Germ-free (GF) and conventionalized (CV) rats three weeks of age were fed a commercial CL-2 diet for four weeks. The diet was sterilized by autoclaving (127°C, 30min). The gut contents were then collected from the stomach, the upper, middle and lower small intestine, the cecum and the colon-rectum. The concentrations of protein nitrogen (PN), non-protein nitrogen (NPN), amino acid and ammonia were then estimated. PN concentrations in the small intestinal and cecal contents of CV rats were higher than those of GF rats. The free amino acid concentrations in cecal and colonic-rectal contents of GF rats were higher than those of CV rats. Ammonia concentrations in the contents of all six regions from CV rats were higher than in those from GF rats. No difference was observed between CV and GF rats with regard to total amino acid concentration.

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Green tea leaves collected from 20 prefectures in Japan were analyzed for their zinc content in two laboratories (Lab. A, Lab. B) by atomic absorption spectrophotometry. Of 77 samples, 10 were analyzed in Lab. A, 62 in Lab. B and 5 in both, in order to estimate the degree of interlaboratory variation. Tea infusion was also analyzed for its zinc content. 1. The difference between the two mean values obtained. from the two laboratories for the same 5 samples was significant, but it was less than 5% of the mean. The variation derived from repetition of measurement in Lab. B was around 4%. 2. Zinc content in the 77 samples of green tea leaves was 34.6±8.8 (mean±standard deviatian) μg/g, the value being comparable with those mentioned in the literature. 3. Infusion rate (the rate of zinc transferred from tea leaves to infusion) increased from 20% to 30% to 40%, as the infusion time was increased from 60 sec to 90 sec to 180 sec.

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Four kinds of proteinaceous cysteine proteinase inhibitors (CPI) of different molecular weight causing inhibition of cathepsin B were found to be present in chicken breast muscle. The inhibitors were extracted from the muscle with neutral buffer solution, adsorbed on a DEAE-cellulose column at pH 7.2, and eluted with an NaCl gradient of 0.07-0.15M. The eluted CPI were then fractionated with acetone, An inhibitor with a molecular weight of 58, 000 was found by Sephadex G-75 column chromatography in the CPI fraction which was precipitated by 33-55% acetone. Other inhibitors with molecular weights of 10, 000, 22, 000 and 32, 000 were also found by Sephadex G-75 column chromatography in the CPI fraction which was precipitated by 55-77% acetone. The 10, 000-dalton inhibitor (I-S) was then subjected to Sephadex G-50 column chromatography and exhibited a specific activity which was 400 times higher than that of the crude extract. When the 22, 000- and 32, 000-dalton inhibitors were mixed with 0.1% mercaptoethanol and subjected to Sephadex G-75 column chromatography, they were found to be converted to a monomeric inhibitor with a molecular weight of 11, 500 (T-M). I-M was then subjected to Sephadex G-50 column chromatography and exhibited a specific activity which was 600 times higher than that of the crude extract. I-S and I-M were stable between pH 4 and 7. The residual actiVities after heating of I-S and I-M at 100°C for 10min were 70% and 64% of the initial value, resgectively.

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The dietary fiber contents of Lettuce, Celery, Sweet pepper, Cucumber, Spinach, Eggplant and Chinese cabbage commercially available in Tokyo were deterrmined gravimetrically using the partly modified method of Asp et al. involving enzymatic digestion. Recovery tests performed on cellulose powder gave a recovery of 101.5%, and those performed on model samples containing potato starch and casein gave recoveries of 1.73 and 1.02%, respectively, using mixtures of 6: 4 and 8: 2. These results indicated that the digestive ability of enzymes to remove starch and protein in samples was sufficient under the experimental conditions used. The total dietary fiber contents of these vegetables were 1.1-2.3% fresh weight, which were 1.40-1.81 times higher than those obtained by the neutral detergent fiber (NDF) method of Van Soest using the same samples. The results suggested that some components of dietary fiber might be dissolved by the NDF reagent.

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The effect of wounding Japanese radishes by slicing on their organic acid composition was investigated. The pH of wounded Japanese radishes decreased, and their organic acid composition changed during storage. The organic acids in the sliced tissues were qualitatively and quantitatively analyzed by isotachoelectrophoresis. The level of malic acid, which is a major organic acid present in Japanese radish, tended to increase temporarily at 5°C, 10°C and 20°C after the tissues had been cut. Under anaerobic conditions, lactic acid was produced at 10°C and 20°C after 24h, and acetic acid was produced at 24°C after 48h. Moreover, lactic and acetic acids were found in the sliced tissues without sterilization at 24°C after 48h. These results suggest that it is necessary to preserve sliced tissues at low temperature for a short time in order to protect them from changes in their constituents.

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