(I) Interaction between vitamin B₁ and calcium or magnesium -animal experiments-
Effects of calcium and magnesium deficiencies on vitamin B₁ metabolism: (a) In rats fed a calciumdeficient diet for 4 weeks, the concentration of thiamin in synaptosomal and myelin-membrane fractions in the brain was decreased and the ratio of free thiamin to total thiamin and the amount of nonprotein-bound thiamin were increased in the brain. In rats fed a magnesium-deficient diet for 4 weeks, the concentration of thiamin in liver and the activities of thiamin-dependent enzymes in the liver were decreased. (b) In rats fed a calcium-deficient, low-thiamin (20μg/100g diet) diet, typical neurological symptoms of thiamin deficiency occurred and sometimes the rats died. When thiamin was administered to these rats, they recovered quickly. In these rats, growth, body temperature, blood pressure and heart rate were decreased, and the thiamin level in the nervous system and heart was also decreased the level of calcium in the telencephalon was decreased only in these rats. These results indicate that calcium plays a role in the binding of thiamin to nerve membrane structures, thus playing a specific role in the process of nervous conduction. In contrast, magnesium has little effect on thiamin in nerve tissues, but may play an important role in thiamin-dependent enzyme systems in the liver.
(II) Survey of nutrient intake and vitamin B₁ status of farm villagers in northeast Thailand
To clarify the health and nutritional (especially vitamin B₁) status of inhabitants in rural Thailand, a medical survey study and a survey of food habits were carried out in a farm village with a population of about 1, 000 in northeast Thailand. In this report, the food intake, thiamin status and biochemical blood status of farm villagers and company employees are presented. (1) From the results of the food survey, it was apparent that a) foods for these villagers were mainly glutinous rice and immature papaya, with some fish, chicken, chilli and leaf vegetables, b) intakes of calcium, vitamin B₁ and vitamin B2 were deficient in this group compared with the recommended values for Thailand, c) the sources of nutrients were mainly glutinous rice and the most potent source of retinol was chilli. (2) From the results of biochemical plasma and blood examinations, spread of infections diseases including chronic hepatitis was evident in inhabitants of this area, especially in company employees, and there were many marginal nutritional deficiencies, especially in the villagers. (3) Thiamin intake and blood thiamin levels were very low. From these results, it is postulated that many diseases will be induced by these nutritional deficiencies.

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Nutritional education and meal planning for preschool children have been based on the Recommended Dietary Allowance for Japanese. In recent years, much attention has been paid to preschool children affected by obesity and hypercholesterolemia. In spite of their reduced daily activity, the children had been continuing to eat in excess, resulting in an over-intake of energy. To study the proper balance of daily energy intake and expenditure in healthy children, resting metabolism, daily energy intake and expenditure were measured in 188 preschool children in two selected kindergartens. The results obtained were as follows: 1) Calculated energy expenditure (kcal/kg/min) based on oxygen consumption (Vo₂) and respiratory quotient (RQ) for boys was found to be higher than that for girls. 2) Estimated basal metabolic rate was found to be 2.1% (6-year-old boys) to 18.3% (6-year-old girls) lower than the data cited in the RDA for Japanese, except for 5-year-old boys and 3-year-old girls. 3) The physical activity index (χ) ranged from 0.467 to 0.577 for boys and from 0.363 to 0.426 for girls of 4 and 5 years old. 4) Children who showed higher energy intake were found to show a lower physical activity index, and thus they showed a larger inbalance between energy intake and expenditure.

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Forty healthy female college students underwent gustatory function tests for salt (discrimination of salt concentration, salt taste threshold), biochemical parameter measurements (plasma Zn, plasma Na, plasma retinol, plasma retinol-binding protein (RBP)) and a five-day dietary consumption survey. In the tests, performed six times, individuals, rate of correct discrimination (RCD) between 0.6% and 0.7% NaCl concentration was 51.2+28.7%. Only eleven (28%) subjects were able to make a correct discrimination. No significant association was found between the RCD and either the detection or recognition threshold for salt. Plasma Zn, retinol and RBP levels were lower in the present subjects than in our previous studies. Plasma Zn level in 20% of the subjects was lower than 0.7 μg/ml. Correlations among plasma Zn, retinol and RBP were positively significant. From these associations and the finding that Zn is indispensable for the biosynthesis of RBP, it can be postulated that Zn influences vitamin A metabolism. These subjects showed low energy and nutrient intake (per kg body weight) levels except for protein. There was a significant correlation between Zn intake (per kg body weight) and the plasma Zn level. The RCD was correlated positively with plasma Zn. Although the level of significance did not exceed 0.05 (r=0.282, p=0.078), this tendency indicates that the plasma Zn level is related to RCD. There was a significant difference in plasma Zn level between the high and low RCD groups. With regard to the RCD, only the plasma Zn level showed a marginally significant partial regression coefficient (p=0.096) in multiple regression analysis. Thus, it was suggested that the plasma Zn level might have influenced the discrimination of salt concentration.

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A studY was conducted on the effect of melanoidin, a brown and polymeric pigment which is finally accumulated in the Maillard reaction, on the activity of α-amylase from human salive. Melanoidin was prepared by the reaction between D-glucose and glycine. Soluble starch and maltotetraose were used as substrates for digestian. The enzymatic reaction medium was 0.02M sodium phosphate buffer (pH6.0) containing 1mM CaCl₂. The reaction solution was incubated at 37°C. Oligosaccharides produced on digestion were determined by high-performance liquid chromatography. Melanoidin was found to exert an adverse effect on the activity of α-amylase. The effect of melanoidin on the enzyme was attributed to non-competitive inhibition on the basis of Lineweaver-Burk and Dixon plots. The Michaelis constant (K_m) and inhibition constant (K₁) were 3.3mM and 0.1-1.5%, respectively. The following factors were suggested to be involved in the inhibitory effect of melanoidin: (1) Interaction between the enzyme molecule and melanoidin. (2) Interaction between the substrate and melanoidin. (3) Interaction between Ca ions and melanoidin. Melanoidin was also found to constrain the thermalinstability of α-amylase.

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The effects of intake of a small amount of 4^G-β-D-galactosylsucrose (lactosucrose, LS) intake on fecal flora and properties were studied in eight healthy volunteers, who consumed a mixed free-choice diet (control diet), or the same diet with 1g LS/day, 2g LS/day or 3g LS/day. During the intake of LS, bifidobacteria were increased significantly, and lecithinase-positive clostridia including C. perfringens and fecal ammonia were decreased significantly. Fecal concentrations of sulfide showed a significant decrease during intake of 2g LS/day or 3g LS/day. No significant change was observed in water content or stool weight, but a slight change occurred in the fecal pH value during intake of 3g LS/ day. These results indicate that the minimum effective dose of LS in healthy adults is 1-2g/day.

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Biochemical changes in colon mucosa were studied in rats fed diets containing soluble dietary fiber (pullulan, polydextrose or pectin), and compared with those in rats fed a 5% cellulose diet (control). Cell size in the colon mucosa seemed to be reduced in the groups fed the pullulan and pectin diets, since the protein content was decreased and the DNA content was increased. In the rats fed polydextrose, the colon mucosal cells seemed to be enlarged, as suggested by an increase in their protein and DNA contents, similar to that in the control. From scanning electron micrographs, the haustra coli appeared broader in rats fed the pullulan diet and were more rounded and larger in rats fed the polydextrose diet than in the control rats. In rats fed the pectin diet, the colon showed an irregular surface structure. The above changes in the haustra coli were more marked in the 10% than in the 1% dietary fiber group.

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Male 3-week-0ld Wistar rats were weaned, divided into two groups, and fed a commercial diet. Rats aged 4 weeks were fasted far 26h, and sacrificed tagether with rats which had been fed a diet ad libitum. The synthesis of polyunsaturated fatty acid (PUFA) by brain and liver microsomes was examined using [1-¹⁴C] 18: 3 (n-3). The synthetic ability of liver microsomes was considerably decreased in the fasted group (p<0.05), whereas that of brain microsomes was less affected. The phospholipid content of the liver (per unit tissue weight) was significantly decreased in the fasted group (p<0.05), although the cholesterol content did not change despite the considerable decrease of liver weight. Furthermore, a decreased phosphatidylcholine/phosphatidylethanolamine ratio and an increased PUFA concentration in liver lipids were observed in the fasted group (p<0.05), as compared with the control group. These results suggest that the liver phosphatidylcholine content was decreased in the rats subjected to fasting.

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We have previously confirmed that lipid metabolism in experimental animals is affected by exposure to noise. The present study was conducted to investigate the effects of non-noise or noise exposure on lipid and nitrogen metabolism in rats fed a porcine plasma peptide diet. Male Wistar rats (100-120g) were fed either a 25%casein diet (group C), or a porcine plasma peptide diet in which half of the casein was replaced by porcine plasma peptide. The latter animals were subdivided into non-noise (grouP) and noise exposure (group P-N) groups. Rats in group P-N were exposed to noise of 3, 000Hz, 95 phone for 8h per day. Al1 the animals were fed the experimental diets ad libitum for one week. Serum and liver cholesterol, triglyceride and TBA values, and urinary nitrogen and corticosterone excretions were then determined. Food consumption in group P was higher than that in group C or P-N, but body weight gain did not differ among the three groups. Serum total cholestero1, and urinary corticosterone excretion in group P-N were increased significantly compared with group P. However, liver total cholesterol, triglyceride and the TBA value in group P-N were lower than those in group P, The ratio of urinary N excretion/N intake (%) in group P-N had a tendency to be higher than that in group P, but there was no significant difference between the two groups.

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In order to identify the possible relationship between structural impairment and compositional changes resulting from storage of gingko nuts, we analyzed the concentrations of starch, oligo- and monosaccharides and organic acids bimonthly in nuts stored at 5, 20-35, and 37°C over a six-month period. The nuts stored at 5°C showed a reduction of fructose and an increase in sucrose, whereas the sucrose content was decreased considerably in nuts hardened by starage at room temperature or higher. There was no significant difference in starch content during the period of study, and the observed decrease was only slight at each temperature tested. Hence, the changes in content could not be attributed to hardening of the gingko nuts in storage. For comparison, we also assessed the amounts of starch, oligo- and monosaccharides and organic acids in gingko nuts ripening in seasan. The nuts matured rapidly during about 20 days between mid-July and early August, then continued to ripen very gradually until the end of October. Maturation was confirmed by an increased starch content and a decreased water content.

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The permeability of water-insoluble dietary fiber from cabbage and bamboo shoots to authentic dextrans and maltodextrins was investigated by gel-filtration chromatography. Maltodextrins having a molecular weight of less than about 2.0×10³ completely permeated into the pores of the Wall matrix in the dietary fiber. In addition, the influence of different levels of this water-insoluble dietary fiber on glucose diffusion speed was examined. The glucose diffusion speed decreased as the concentration of the dietary fiber increased. This was considered to be due to the permeability of the water-insoluble dietary fiber to lower-molecular-weight carbohydrates.

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