The biosynthesis of biotin-vitamers from unsaturated higher fatty acids by the resting cell system of bacteria was investigated. Biotin-vitamer formation from oleic, linoleic and linolenic acids was found in certain bacteria belonging to the genera Enterobacter, Agrobacterium, Bacillus, Escherichia and Micrococcus. The biotin-vitamers were identified as a mixture of 7, 8-diaminopelargonic acid, desthiobiotin and biotin. Metabolites other than biotin-vitamers from those fatty acids were analyzed by gas-liquid chromatography and mass spectrometry. Linoleic, oleic, C-17 and C-15 saturated fatty acids were identified as the main metabolites of linolenic acid. The pathway of biosynthesis of pimelic acid from linolenic acid by a strain of Bacillus sphaericus AKU 0227 was also studied.
The effect of dietary orotic acid on the levels of liver and blood NAD in young rats was investigated. Weanling rats were fed on a nicotinic acid-free, 20% casein diet containing 0% (control diet) or 1 orotic acid (test diet) for 32 days. Retardation of growth, development of fatty liver and enlargement of liver were observed in the test group in comparison with the control group. In the test group, the amounts of quinolinic acid, niacin, NAD and N1-methylnicotinamide, and the activities of quinolinate phosphoribosyltransferase, nicotinamide mono-nucleotide adenylyltransferase, nicotinamide methyltransferase and NAD synthetase expressed in terms of g liver were significantly decreased compared to the control group. When these values were expressed in terms of whole liver, a significant difference was observed in the content of NAD and the activity of NAD synthetase between the control and the test groups. The activity of aminocarboxymuconate-semialdehyde decarboxylase expressed in terms of whole liver was about 2-fold higher in the test group than in the control group, but was not significantly different. The levels of NAD in blood as well as in liver were significantly lower in the test group than in the control group. Urinary excretions of quinolinic acid, niacin and N1-methylnicotinamide were also reduced in the test group. These results are discussed in the light of the reported effect of orotic acid in lowering the level of ATP in liver.
Tne dietary effects of phytosterol and polyunsaturated fat (PUFA-fat) on the cholesterol and fatty acids levels in serum and liver of female rats were studied, with the following results. (1) Addition of 1 cholesterol with 0.25% cholic acid to a 10% butter diet increased cholesterol levels and decreased the ratio of polyunsaturated fatty acid (PUFA) to saturated fatty acid (SFA) in the serum and liver. These changes diminished upon additions of phytosterol and PUFA-fat (cod liver oil) to the 10% butter-cholesterol diet. (2) While the cholesterol-rich diet increased the fatty acid content of the liver, addition of phytosterol to the butter-cholesterol diet depressed this increase. On the other hand, addition of PUFA-fat to the butter-cholesterol diet caused an increase of total fatty acid in the liver. (3) A negative relationship was found between the cholesterol level and the ratio of PUFA to SFA in serum (γ=-0.810) and also in liver (γ=- 0.548). There were significant positive correlations between the values for the serum and liver cholesterol levels (γ=0.720) and also between the respective values in the ratios of PUFA to SFA (γ=0.521). These results indicate that dietary phytosterol and PUFA-fat modulate the levels of cholesterol in proportion to the increase in the ratio of PUFA to SFA in both serum and liver with the cholesterol diet, and show that the changes in the values for the serum reflected in changes in the liver.
The effects of branched-chain amino acid (BCAA)-enriched nutrient mixture (nutrient-mixture) on the nitrogen metabolism and nutritional state were clinically investigated in 10 patients with liver cirrhosis. Nutrient-mixture-supplemented diet was prepared by adding 150 g nutrient-mixture daily to low-protein diet, and comparisons were made with a regular diet (control diet). Each diet supplied 2, 100 kcal energy and 80 g protein per day. Patients were given control diet for 2 weeks and thereafter treated successively with nutrient-mixture-supplemented and control diet each for 2 weeks. Nitrogen balance improvement and positive balance were observed during the feeding of nutrient-mixture-supplement-ed diet. The composition of nitrogen compounds in urine and the fecal nitrogen excretion did not alter during the test period. Plasma aromatic amino acid (AAA) concentrations decreased and BCAA/AAA molar ratios increased significantly during the 1st and 2nd week of nutrient-mixture-supplemented diet administration. Plasma methionine concen-tration also decreased in the 1st week. Plasma pre-albumin levels rose significantly during the 1st and 2nd week of nutrient-mixture-supplemented diet administration, and the number connection test improved significantly following the supplemented diet. These results suggest that the use of nutrient-mixture in the nutritional treatment of liver cirrhosis had no deleterious effects on nitrogen metabolism and is useful for the improvement of plasma amino acid imbalance and protein-energy malnutrition.
3-Acetylpyridine, an antagonistic agent of nicotinic acid, was given to suckling rats from 6 days of age. Rats were killed at 6, 9, 12, 15, 18, 21, 24, 27 and 30 days of age respectively, and their brains were analyzed for several biochemical parameters of brain growth and myelin-ation for comparison with those of pair-fed and ad libitum control rats. Results of DNA, RNA and protein content measurements in the brain of rats which had received 3-acetylpyridine and of pair-fed control suggested a retardation of about one week in brain growth and development compared to ad libitum control with most striking differences noted at 12 days of age. At 30 days of age, rats which had received 3-acetylpyridine showed lower values in yield of myelin, content of cerebroside and specific activity of 2', 3'-cyclic nucleotide-3-phosphohydrolase, when compared with pair-fed and ad libitum controls. These results indicate that under-nourishment due to restricted food intake during brain growth-spurt results in retardation of brain development to some extent. They also suggest that nicotinic acid plays an important role in myelination associated with synthesis of cerebroside which contains high levels of long-chain fatty acid.
The changes of the transmural electrical potential difference (ΔPD) evoked by infusion of glucose, maltose . and sucrose and the disaccharidase activities in the everted intestine were studied in diabetic rats. After the induction of diabetes by streptozotocin, ΔPDs evoked by sugars and the enzyme activities were observed in the jejunum and ileum. ΔPDs evoked by glucose, maltose and sucrose markedly increased both in the jejunum and ileum of diabetic rats. The Kt values for these sugars in diabetic rats were the same as those of control rats. The Vmax values were significantly increased in the ileum of diabetic rats. Maltase and sucrase activities in the ileum increased in diabetic rats. Highly significant linear correlations were found between the ΔPDs evoked by glucose and the ΔPDs evoked by maltose or sucrose both in the jejunum and ileum of control and diabetic rats. However, ΔPDs evoked by maltose and sucrose did not correlate with maltase and sucrase activities in the jejunum. In the ileum, ΔPDs evoked by sucrose correlated with the sucrase activity which was very low. These results suggest that the increase of transport of glucose derived from disaccharides in the diabetes induced by streptozotocin is mainly due to the increased activity of the glucose transport system, but not due to the increase of disaccharidase activities.
The effect of dietary fat on the activity of rat liver α-amino-β-carboxymuconate-ε-semialdehyde decarboxylase [EC 4.1.1 .45] (ACMSD), a key enzyme of tryptophan-niacin metabolism, was investigated. When high-fat diet was given to rats for a week, the activity of ACMSD in the liver was extremely suppressed, but not in the kidney. The liver enzyme activity was correspondingly and constantly reduced half by increasing soybean oil in the diet in 4% stages. The potency of suppression of the enzyme activity in liver was found to be different between soybean oil and lard in diets. Among various dietary fatty acids, saturated fatty acid was observed to be less effective. Unsaturated fatty acids, however, were shown to be suppressive and polyunsaturated fatty acids such as linoleic and linolenic acids more effective than oleic acid in suppressing liver ACMSD activity. These suppressive effects of dietary unsaturated fatty acids on the liver ACMSD activity were not considered to be caused by their direct effect on the enzyme protein. Moreover, neither inhibitor nor activator was thought to be involved in the alteration of the enzyme activity.
The present paper describes the effects of long-term (17-19 months) feeding of high-iodine eggs on lipid metabolism and thyroid function of rats, and also the effects of inorganic iodine on lipid metabolism. Rats were meal-fed on a diet containing 1% (w/w) of or-dinary egg powder (OE diet as control:35μg 1/100g) or high-iodine egg powder (IE diet: 392μg 1/100g). After the 19-month dietary treatment, rats fed on the IE diet, compared with the controls, showed a higher tissue lipoprotein lipase activity, a lower lipid peroxide level in the brain and a trend toward lower serum triacylglycerol levels and body fat storage without alterations in serum levels of thyroid-related hormones (TSH, T3 and T4). From the results of cold exposure and anti-thyroid drug-treatment conducted on rats fed on the OE and IE diets for 17 months, high-iodine eggs seemed to improve the age-related defects in thermogenic and thyroid hormone responses to cold, and also to result in a resistance to the anti-thyroid drug. The effects of the IE diet on lipid metabolism of rats were partly exhibited by feeding of the OE diet with an equivalent amount of iodine added as KI or KIO3. Thus, it is suggested that iodine ingestion through high-iodine eggs modulates both lipid metabolism and thyroid function in rats.
The effects of a high-protein diet on insulin and glucagon secretion in ventromedial hypothalamic (VMH) Lesioned and shamoperated (sham) rats were studied in vivo as well as in perfusate from isolated pancreas. Two weeks after VMH destruction or sham operation, the rats were given either a balanced diet (protein 27%, carbohydrate 61%, fat 12%) or a high-protein diet (protein 55%, carbohydrate 30%, fat 15%) for the following 2 weeks. The calorie intake and body weight changes after the commencement of the diets were almost the same in the groups of VMH lesioned rats, but these were much greater than those in the two sham-operated groups. Fasting blood glucose, plasma insulin, and plasma glucagon concentrations were also similar between the two VMH groups, but in the sham-operated rats fasting blood glucose and plasma insulin concentrations of those rats on high-protein diet were significantly increased when compared to those on balanced diet. In the isolated, perfused pancreas, an arginine-induced excess insulin and glucagon secretion was not significantly different between the VMH lesioned rats. An arginine-induced rise in insulin concentration in the sham-operated rats on high-protein diet was significantly higher than for rats on balanced diet. We therefore suggest that hyperinsulinemia already produced in the VMH lesioned rats may not be influenced by the change in the composition of the dietary protein and carbohydrate.
The present study was designed to estimate dermal nitrogen losses in summer and winter under the conditions of minimal daily activities, on a diet of standard . Japanese protein intake level and to determine whether the increased dermal nitrogen losses induced by hot climate or exercise were compensated for by the decrease in urinary nitrogen excretion. Six healthy male university students served as the subjects. The daily dermal nitrogen losses (mean ±SD) were 0.22±0.07g or 3.10±0.58mg/kg in winter and 0.44±0.19g or 6.35±2.46mg/kg in summer, showing significantly higher dermal nitrogen losses in summer than in winter. On the contrary, urinary nitrogen excretion tended to be larger in winter than in summer. Thus, renal compensation seemed to exist for the seasonal changes in dermal nitrogen losses. In the summer experiment, the subjects took light exercise besides the minimal daily activities for a 2-day exercise period. The pooled mean of daily dermal nitrogen losses during the exercise period was significantly larger than that during the sedentary period, while the urinary nitrogen excretion was almost the same in the two periods. No compensatory reduction in the urinary nitrogen excretion during the exercise period was observed under the conditions of the preseni study.
The possibility that cycloartenol magnifies the hypocholes-terolemic effect of β-sitosterol was studied in two strains of rats fed on cholesterol-enriched (0.5%) diets. Cycloartenol was added to diets containing 1.0% or 0.5% β-sitosterol at the 0.05% level and to diet free of plant sterol at the 0.5% level. In one experiment, diets included sodium cholate (0.125%). Due to the potent hypocholesterolemic efficacy of β-sitosterol under the present dietary regimens, no clear additional effect (so-called synergistic effect) of cycloartenol was observed. However, in the experiment using Wistar rats, the decrease in serum apo A-I due to feeding cholesterol was ameliorated more effectively in combination with β-sitosterol than with β-sitosterol alone. The hepatic deposition of choles-terol was mitigated by dietary β-sitosterol, and further, although slightly, by a combination of β-sitosterol and cycloartenol, except in the experi-ment with diets containing sodium cholate. Fecal excretion of neutral and acidic steroids was not meaningly magnified by cycloartenol. Cycloartenol itself was not as effective as β-sitosterol in mitigating lipid disorders due to dietary cholesterol. The rate of appearance of cholesterol in the thoracic duct lymph was not interfered with further by a combination of β-sitosterol and cycloartenol compared to β-sitosterol alone. This trimethylsterol was absorbed at a rate approximately 4-fold higher than that of β-sitosterol, though much lower compared to cholesterol. These results suggest a preference for cycloartenol in cholesterol dynamics. However, cycloartenol seems unlikely to influence cholesterol absorption in the small intestine.
The effects of dietary fish, soybean protein and casein on cholesterol turnover were compared in rats. After the injection of [14C]cholesterol into the rats, the specific activities of radioactive cholesterol in feces were followed for 4 weeks. The cholesterol half-lives calculated from the decay curves of the specific activities were 14.7 and 14.6 days in rats fed fish protein and soybean protein, respectively. These were shorter than the half-life (17.4 days) in casein-fed controls. The fish and the soybean protein feedings significantly increased the fecal excretions of cholesterol and coprostanol, respectively, and lowered the plasma cholesterol level, as compared with casein feeding. In addition, both fish and soybean protein feedings also increased the excretion of bile acids. The stimulation of cholesterol metabolism and the increased excretions of cholesterol and its metabolites by feeding fish or soybean protein appear to play important roles in the hypocholesterolemic effects.
The utilization of urea nitrogen was examined in 10 healthy adult men from a village near Lufa, in the Eastern Highlands Province of Papua New Guinea. The staple diet of these men was sweet potatoes. [15N]urea was used as tracer for urea released into their intestinal tracts and the utilization of the urea-N was estimated from the trend of 15N. The men were orally given [15N]urea at the beginning of the study and then their daily protein intake, serum protein levels, 15N excretion in the feces and urine, 15N retention in the whole body and 15N incorporation into serum protein were examined. Their daily protein intake (32.2±8.6g/day) was low, but their serum protein level (8.05±0.41g/100ml) was within the normal range. 15N retention in the whole body on day 3 was estimated to be 35.4±20.2% of the total amount administered, calculated from the recoveries in the feces (1.64±0.85%) and urine (63.0±20.5%) on days 1-3. The utilization of urea nitrogen in Papua New Guinea highlanders was confirmed from the finding of 15N incorporation into serum proteins on day 3 (0.008±0.005 atom% excess). This incorporation was negatively correlated with the urinary nitrogen excretion and serum protein level. This correlation suggests that Papua New Guinea highlanders with low urinary nitrogen excretion or a low level in serum protein, who are in a poor state of protein nutrition, tend to utilize more urea nitrogen for the synthesis of serum protein.