Acta vitaminologica et enzymologica最新文献

The effect of dietary anti-alpha-amylase on some aspects of lipid metabolism has been studied after having shown that rats fed proteins from legumes containing anti-alpha-amylase (to cover one-third of the protein quota in the diet) failed to absorb carbohydrates contained in starch to the point that the total caloric intake was sharply reduced and their growth stunted. Upon feeding rats anti-alpha-amylase, destruction of fatty deposits was observed. The animals, on the other hand, did not show evidence of important structural pathology.

Administration of HgCl2 at a dose of 5 mg/kg body weight/day for 15 days to male albino rats brought about a marked depression of the scavenging enzymes viz. glutathione peroxidase and glutathione S-transferase, in kidney. There was an adaptive rise in the levels of catalase and no increased lipid peroxidation was observed. The levels of both glutathione and glutathione reductase were decreased, whereas total thiol increased. In the intoxicated rats, Vitamin-E was effective in bringing back glutathione levels to normal. The adaptation in this group of animals is reflected by increased superoxide dismutase activities. Feeding of Vitamin-E alone could cause a depression of the scavenging enzymes like glutathione peroxidase and glutathione S-transferase along with a slight lowering of glutathione levels.

Serum lipoperoxides were measured, by a modified thiobarbituric acid method, in 25 children affected with malnutrition, 40 adults having hyperthyroidism and 40 adults having hypothyroidism and compared with the serum lipoperoxides content of 40 normal adults. The lipid peroxide content was 3.9 nmol/ml in normals, 1.8 nmol/ml in malnutrition, 2.5 nmol/ml in hyperthyroidism and 3.1 nmol/ml in hypothyroidism. The vitamin E content of the serum in all the cases was found to vary in the same way as the amount of circulating lipid peroxides. The serum inhibitory capacity against in vitro lipid peroxidation, using rat brain homogenate as a model system, was totally abolished in malnutrition and was decreased to about 50% in hyperthyroidism and to about 33% in hypothyroidism, as compared to normal human serum. It is concluded that the level of circulating lipid peroxides in serum is related to the serum vitamin E concentration.

19 adolescents (age 10-16 years) have been tested with respect to their ability to solve a video-game, before and after a three week supplementation with a mixture of sugars + vitamins + carnitine (New-Gen). The validity of such a test has been previously compared with the classical Wechsler-Bellevue Scale. A good correlation was calculated with all the Weschsler items, not related with the cultural-linguistic status. The supplementation of the normal diet with New-Gen was accompanied by a marked improvement of the ability (time and number of trials) to solve the video-game test.

This study has been designed to investigate the possible metabolic consequences of maltitol feeding (replacing 1/3 of the dietary carbohydrates) on the fatty acid composition in various body compartments of the rat. The detailed biochemical analysis of the lipid composition rules out the possible interference of this disaccharide on the lipid metabolism, at least with the dosage and duration of treatment used in the experiment.

Intraperitoneal administration of isoniazid (IN), an antituberculous drug, to mice at a dose of 100 mg/kg body weight induced significant inhibition of serum aspartate aminotransferase (AAT) in several hours. The original activity was not restored readily by in vitro treatment of the sera with pyridoxal phosphate (PLP), in contrast to the rapid activation, by the same treatment, of apoAAT in the sera from control mice. Prolonged incubation with PLP prior to the assay was required to restore most of the lost activity. Serum AAT activity enhanced by experimental and the reversal of the inhibition similarly required prolonged incubation with PLP. The results suggest the possibility that human serum AAT activity measured for clinical diagnosis may be underestimated in cases of IN overdose even if the conditions for in vitro PLP treatment of samples are sufficient for conversion of the apoenzyme to the holoenzyme.

Thyroidectomized rats showed a decrease in ascorbic acid and dehydroascorbic acid, with almost no alterations in the diketogulonic acid in liver and kidney. Total ascorbic acid in urine was found to be increased, whereas glucuronic acid in urine decreased significantly. There were no significant changes in the activities of ascorbic acid synthesizing enzymes. Activities of the degrading enzymes were found to increase significantly in the liver, with no remarkable change in their activities in kidney. Daily administration of thyroxine for 10 days to thyroidectomized rats normalized the activities of dehydroascorbatase and 2,3 diketoaldonate decarboxylase in the liver, whereas single administration of thyroxine on the 7th day after thyroidectomy could not bring about such restoration. It seems that thyroxine has no direct role on ascorbic acid metabolism in rats.

Possible mechanisms responsible for hepatic lysosomal fragility in hypercholesterolemic rats have been investigated. It was found that certain factor(s) present in the intracellular environment of liver were required for the release of lysosomal enzymes. Elevated hepatic dehydroascorbic acid content in hypercholesterolemic rats is thought to render the lysosomes fragile in this pathological state, since this compound was found to labilise the lysosomes in vitro. Quercetin and hesperidin were found to be responsible for lysosomal stability, probably by reducing the content of dehydroascorbic acid to a normal level in the hypercholesterolemic condition.

This study was designed to explore the nutritional value of proteins derived from algal biomasses of genus Spirulina maxima, with a view to the possible use of such proteins in human alimentation. Recently the use of such biomasses has commanded attention both as an alternative source of alimentary protein and as a coadjuvant in diet treatment requiring a reduced caloric intake - this because these substances seem to prolong gastric transit time and so produce a feeling of satiety. Our research was conducted in young growing rats; it provided confirmation of the validity of Spirulina as a protein source in terms of good weight gains by the test animals and freedom from adverse effects; the same research, on the other hand, failed to confirm the effectiveness of these protein materials in reducing caloric intake: throughout the test period, indeed, feed consumption (hence caloric intake) was practically the same in the control lot and in animals receiving Spirulina protein.

Intraperitoneal administration of isoniazid (IN), an antituberculous agent, to mice or rats at a dose of 100 mg/kg body weight resulted in remarkable and rapid inhibition of liver cytosolic aspartate aminotransferase (AAT); inhibition was less marked with other antivitamin B6 compounds; AATs in other tissues and other aminotransferases in liver were less effectively inhibited by IN. The inhibition of liver cytosolic AAT was apparently irreversible in vivo; it was reversed only a little by gel filtration and dialysis to remove excess IN in vitro, although treatment with pyridoxal phosphate or 5'-deoxypyridoxal slowly restored the full activity. Attempts to inhibit the enzyme by in vitro treatments showed that IN itself was not an effective inhibitor, while the liver extracts from IN treated mice contained some strongly inhibitory substance. In addition, the extracts were shown to contain only trace amounts of IN. These results suggest that IN is metabolized to some other form which is markedly inhibitory to murine liver cytosolic AAT, and the metabolite binds to the coenzyme moiety of enzyme in a manner not readily dissociable.