The role of thiamin in the catabolism of ethanol and acetaldehyde has been investigated. When thiamin and subsequently ethanol were administered orally to rabbits, the thiamin concentration in blood increased slightly during the first 3h and then decreased gradually. After 12h, it became lower than the value before thiamin administration. Finally, it reached the lowest value after 24h and then increased slowly to revert to normal in 72h. It is suggested that thiamin participates in the catabolic pathway of ethanol. An oral administration of pyrazole, an inhibitor of alcohol dehydrogenase, followed by ethanol to rabbits caused a delay in ethanol elimination from blood. When acetaldehyde was injected intravenously to rabbits, thiamin concentration and the transketolase activity in blood decreased gradually and after 12h the thiamin level reached its lowest value, then increased slowly and normalized in 72h. Thus, it could be postulated that the decrease in thiamin after an acute ethanol ingestion linked greatly to the acetaldehyde catabolism.
To investigate the metabolism of riboflavin, [2-14C]riboflavin was administered orally to a rat. The urine pooled for 24 h after administration was fractionated by paper and silica gel thin layer chromatographies using various solvent systems. Among the radioactive metabolites, riboflavinyl glucoside was found along with 7-carboxy lumichrome and 8-carboxy lumichrome. The radioactivity of riboflavinyl glucoside comprised about 6% of the total radioactivity excreted in the urine during 24h.
A sensitive radioassay method has been developed to quantitate the activity of the folate-hydrolyzing enzyme which catalyzes the hydrolysis of folic acid to pteroic acid and glutamic acid. The method is based on analyzing [2-14C]pteroic acid separated by a thin-layer chromatography on an Avicel SF cellulose plate using 0.1M potassium phosphate buffer, pH 7.0, as a solvent. This method was found to be more sensitive than a conventional photometric method to determine the activity of the folate-hydrolyzing enzyme. High activities of the enzyme were found in Crithidia fasciculata ATCC 12857, Neurospora crassa IFO 6979 and rat liver. Smaller activities of the enzyme were widely distributed in other microbial cells and mammalian tissues.
The effect of pyridoxal 5'-phosphate on the 1, 25-dihydroxyvitamin D3 receptor system has been studied by using pig intestinal chromatin. Pyridoxal 5'-phosphate did not affect the binding of 1, 25-dihydroxyvitamin D3 to its receptor extracted from chromatin with hypertonic KCI, although in the presence of pyridoxal 5'-phosphate 1, 25-dihydroxyvitamin D3-receptor complexes were not readily precipitated with polyethylene glycol. In contrast, pyridoxal 5'-phosphate showed a potency to dissociate the 1, 25-dihydroxyvitamin D3 receptor from chromatin in a dose-dependent manner. A low concentration of pyridoxal 5'phosphate was as effective as hypertonic KCl in dissociating the receptor from chromatin, while pyridoxine, p-nitrophenyl phosphate, or inorganic phosphate was much less effective. These observations suggest the inhibitory effect of pyridoxal 5'-phosphate on the recognition of 1, 25-dihydroxyvitamin D3 by its receptor system.
Diurnal changes in tissue glycogen stores were determined in rats in relation to the feed timing of sucrose. Rats were daily meal-fed on a 35%, sucrose diet at 20.00-21.00 and a basal diet at 08.00-09.00, or meal-fed on the same diets at the reversed time for 7 weeks. Half of the animals were allowed voluntary wheel-running between 21.00-08.00, but the remaining animals were restricted to exercise for 24 h. At the end of the feeding period, both groups of rats were killed at 4-h intervals. Glycogen stores in liver and soleus muscle of sedentary rats showed sharp increases over 8h after the sucrose meal regardless of its feed timing. The increases continued for only 4h in exercised rats given the sucrose diet at the evening meal time. In contrast, glycogen stores in these tissues did not show any noticeable increase after the basal diet regardless of its feed timing. Thus, the feeding of sucrose at the evening meal time seems to be more preferable than at the morning meal time in order to have higher glycogen stores in liver and skeletal muscle during the physically active phase of the day in rats. Diurnal changes of glycogen contents in heart and adipose tissue differed from those in liver and skeletal muscle.
This study was conducted to know the possibility that pectin-induced alterations in lipid metabolism of animals might be partly ascribed to galacturonic acid produced by the degradation of ingested pectin in the digestive tract. After a 4-week meal feeding twice a day, fasted rats were fed glucose and fructose and 3 h later orally administered 213 mg of pectin (from apple) or galacturonic acid per kg of body weight, or fed water alone. Significant changes in serum and liver lipids were observed 30 min and 1 h after the administration of pectin and galacturonic acid but not 5 h after the administration. Pectin and galacturonic acid showed contradictory effects on serum lipids, adipose tissue lipoprotein lipase activity and triacylglycerol (TG) production and removal rates. However, the elevation of total lipid and TG levels in liver with the sugar feeding was significantly inhibited by the administration of either pectin or galacturonic acid. These results support our hypothesis that galacturonic acid produced by the degradation of ingested pectin in the digestive tract may be partly responsible for the pectin-induced changes in lipid metabolism. This was discussed in relation to another possible regulation of lipid metabolism by short-chain fatty acids which are produced by the intestinal fermentation of pectin and galacturonic acid.
The intestinal absorption of dinitrophenyl-lysine (DNP-lys) was studied with a special interest on the role of the immune system in the absorption of small molecules which are recognized as nonself. [3H]-DNPlys was rapidly absorbed by ligated intestinal loops in situ via a saturable and unique route. When [3H]-DNP-lys was preincubated with the immune serum obtained from rats immunized with dinitrophenylated bovine serum albumin (DNP-BSA), the [3H]-DNP-lys absorption was depressed. The absorption of [3H]-DNP-lys in DNP-BSA-immunized rats was depressed compared to the control. The results obtained suggest that the immune system play a role in avoiding the absorption of small molecules with antigenicity.
The changes in the activity and content of sucrase-isomaltase complex (S-I) in the intestinal mucosa were studied during the development of diabetes induced by streptozotocin in rats. On days 0, 1, 3, 5, and 10 after an intraperitoneal injection of streptozotocin (70mg/kg), the enzyme activity and the enzyme content were observed in the jejunum and ileum. Sucrase and isomaltase activities markedly increased from the 3rd day both in the jejunum and ileum, and kept increasing till the 10th day especially in the ileum. The enzyme content of S-I also increased in parallel with its activity during the development of diabetes. However, in the early stage of diabetes, sucrase activity per μg of S-I content increased both in the jejunum and ileum. Isomaltase activity per μg of S-I content increased temporarily in the ileum. These results suggest that the increase of disaccharidase activities in the early stage of diabetes induced by streptozotocin is not only due to the increase of the enzyme content, but also due to the change of the enzyme catalytic property.
Ten-week old rats were fed an AIN-76 purified diet ad libitum and were given 3-acetylpyridine which is an antagonistic agent of nicotinic acid. The quantity and composition of myelin in the brain were analyzed after administration of 3-acetylpyridine for 40 days. Body weight, myelin yield, cerebroside level and specific activity of 2', 3'-cyclic nucleotide-3'-phosphohydrolase in the brain decreased by administration of 3-acetylpyridine. Despite the decreased myelin yield, the proportion of protein and total lipid and the percentage composition of lipid in myelin did not change by administration of 3-acetylpyridine. Therefore, we have concluded that 3-acetylpyridine plays a significant role in the loss of myelin.
There are several antinutritive factors in the Kintoki bean such as lectin, trypsin inhibitor, lack of methionine etc. The present experiment has revealed that lectin is mainly responsible for the growth impairment of experimental animals orally fed raw Kintoki bean. Mice fed raw Kintoki bean as the only protein source lost their body weight and died in 8 days, while mice fed the heated bean grew normally. When mice on a 10% albumin diet ingested 20mg or 40mg or 60mg Kintoki bean lectin by daily stomach-feeding, their body weights were reduced to 84%, 74%, 71% of the control group after 5 days respectively and some of them could not live to complete the experiment. The apparent rates of the intestinal absorption of carbohydrate, lipid, and protein were considerably reduced, when rats were fed a diet containing 0.4% lectin. Especially, the rate of protein absorption was decreased to 26.3% from 55.5% of the control rate. The main tissues of mice that had ingested Kintoki bean lectin by stomach-feeding were subjected to microscopic observation. No changes were observed in the liver, kidney, spleen and pancreas. But in the small intestine, the epithelial cells lining the villi were considerably disordered and conspicuously disrupted. These results indicate that the Kintoki bean lectin is one of the most promoting factors for growth impairment in experimental animals and that the first target organ in the case of oral feeding is the small intestine.
To determine the effect of a certain diet on the intestinal flora of rats, the cecal flora of rats fed a low protein or low lysine diet was examined. Total counts of bacteria in the cecal contents of rats given the four kinds of diet (a normal protein diet, a low protein diet, a normal lysine diet and a low lysine diet) were not significantly different. The counts of Streptococcus, Enterobacteriaceae, and Clostridium perfringens in the cecal contents from rats fed the low protein diet were significantly lower than those from rats fed the normal protein diet. The count of Lactobacillus in the cecal contents from rats fed the low lysine diet was significantly higher than that in those from rats fed the normal lysine diet. Levels of most of the free amino acids in the cecal contents of the low protein group were significantly lower than those of the control. But no significant difference was found between the levels of most of the free amino acids in the cecal contents of the low lysine group and those of the control group.
Leaf proteins obtained by coagulation at different pH were examined for their chemical composition and nutritional quality. Green juice was extracted from alfalfa, red clover, Italian ryegrass and oats and leaf protein was coagulated by heating the juice after adjusting the pH to 4 or 8-8.5, or without any adjustment of the pH (about pH 6). The mild alkaline juice from Italian ryegrass and oats did not cause the satisfactory coagulation but it was achieved with the addition of Ca salt to the juice before heating. There were no important differences in the amino acid compositions of the leaf proteins coagulated at different pH. Crude ash, Ca and Mg contents increased with an increase in pH of coagulation and the protein coagulated at pH 8 had remarkably high contents of crude ash, Ca, Mg, Na and P in each crop. The leaf protein coagulated at pH 6, on the contrary, had a high content of true protein and low contents of nitrogen free extracts and nucleic acid as compared with those at pH 4 and 8. The pH of coagulation of leaf protein from alfalfa and red clover had no effect on the nutritional quality of the respective proteins. In Italian ryegrass and oats, however, the leaf protein coagulated at pH 8 was found to be nutritionally inferior to those coagulated at a lower pH. The data presented in this work support that in general, the leaf protein produced by heating the green juice without any adjustment of pH may be suitable for protein resources because of its desirable properties, i.e. high true protein content and good nutritional quality.
The chemical composition of dry seeds of four varieties, pods, stalks and leaves of winged beans (Psophocarpus tetragonolobus) was determined. The seeds had a high range of protein (27.8-36, 6%) and fat (14.8-17.9%), which were similar to soybeans. The seeds contained high phosphorus, calcium and magnesium. The leaf was highest in protein content (33.7%) of all the parts studied except for the seeds. The protein and fat content of pods decreased as pods ripened. The calcium content in the leaf was much higher than in the other parts. Protein was extracted sequentially with 2% NaCl, 30% isopropyl alcohol, 4% lactic acid and O.5% KOH from dry seeds of four varieties of winged beans. The NaCl extract showed the highest range of protein concentration (60.2-77.6%). The NaCI extract was separated into two fractions based on solubility in water. The amino acid composition of the flour from the seeds and of the two fractions from the NaCl extract were determined. Contents of lysine, aspartic acid, glutamic acid and leucine were large, while the sulfur-amino acid content was small. Tyypsin and chymotrypsin inhibitory activities of 2% NaCI extract from the seeds were determined, and chymotrypsin inhibitory activity was higher than the trypsin.
The effect of pyridoxine on 6-azauridine triacetate (6-AzUrd-TA) induced hyper β-alaninemia was studied in New Zealand albino rabbits in three experiments. In each of the three experiments the animals were administered by gavage: Group 1 (Control), drinking water; Group 2, 6-AzUrd-TA; and Group 3, 6-AzUrd-TA with pyridoxine. While no β-alanine was found in the control group or in pretreatment samples of the 6-AzUrd-TA and 6-AzUrd-TA+pyridoxine treated animals, high concentrations of this amino acid (191.0±91.6, 220.2±116.3, 103.2±64.4 nmol/ml) were found on the fourth and seventh days of 6AzUrd-TA treatment with daily doses of 1.0g/kg and 0.5g/kg B.W. respectively. The drug induced hyper β-alaninemia was significantly (p≤0.05) reduced in all three experiments by simultaneous pyridoxine administration in daily doses of 50mg/kg B.W. These results indicate, that daily repeated oral administration of 6-AzUrd-TA causes elevation of serum β-alanine, which can be partially prevented by oral administration of pyridoxine. They also indirectly support the hypothesis, that 6-AzUrdTA induced hyper β-alaninemia is at least partially caused by the inhibition of β-alanine degrading enzymes, that use pyridoxal phosphate as a coenzyme. Direct measurement of the enzyme activity is planned in our future studies.