Showing papers in "Acta vitaminologica et enzymologica in 1983"

Ascorbic acid: a scavenger of superoxide radical.

Abstract: The second order rate constant for the reaction between ascorbic acid and superoxide at pH 7.4 using the xanthine-xanthine oxidase system was estimated to be 5.4 x 10(6) M-1 sec-1. The results indicate that the efficacies of superoxide dismutase and ascorbic acid for catalyzing the decay of superoxide radical in animal tissues are similar. The significance of ascorbic acid as a scavenger of superoxide is discussed from the point of view of evolution of ascorbic acid synthesizing capacity in the terrestrial vertebrates.

Vitamin E and the heart: possible role as antioxidant.

Abstract: When cardiac muscle becomes hypoxic the cells become oedematous and the fine ultrastructure is altered. Developed tension declines and resting tension increases. The cellular stores of ATP and CP are depleted and the mitochondria exhibit an altered respiration, characterized by a reduced state III respiration and a lowered respiratory control index. Reoxygenation results in a further increase of the hypoxic damage. Using these changes in function as indices of the severity of the damage caused by hypoxia and reoxygenation, we have investigated whether the administration of alfa-tocopherol provides protection. Adult male New Zealand white rabbits were used. The hearts were isolated, Langendorff perfused and then made hypoxic. Alfa-tocopherol acetate was infused directly into the aorta inflow cannula, 20 minutes before the onset of hypoxia and was continued for the remainder of the perfusion. Hypoxia was established by substituting 95% N2 and 5% CO2 + CO2 in the gas mixture. The alfa-tocopherol-treated rabbits hearts were protected in that during hypoxia and particularly during reoxygenation had a lower rate or rise of resting tensions and of ATP and CP depletion. This treatment also maintained mitochondrial function after hypoxia and reoxygenation and it resulted in the preservation of the fine ultrastructure of the myocardium as electronmicroscopic examination of the hearts revealed a marked reduction in oedema, contracture-band formation and mitochondria alterations.

Lack of direct association between serum transferrin and serum biochemical indicators of vitamin A nutriture

Abstract: The association between serum transferrin and serum biochemical indicators of vitamin A and protein nutriture was investigated in 295 preschool children. Their levels of retinol and RBP correlated positively and significantly with transferrin, iron, total iron binding capacity (TIBC), total proteins and albumin. However, when removing those cases having unacceptable levels of total proteins (less than or equal to 6.4 g/dl) and/or albumin (less than or equal to 3.5 g/dl), the significant correlation between retinol (or RBP) and transferrin disappeared. It is concluded that transferrin levels are not directly related to the vitamin A nutritional status. The significance of this observation in relation to the known interaction between vitamin A and iron is discussed.

Wernicke's encephalopathy. A case report with neurophysiologic and CT-scan studies.

Abstract: A case of Wernicke's encephalopathy with ataxia, confusion, memory loss, partial seizures of complex behavior and hypothermia, subsequent to thiamine depletion due to chronic malnourishment and triggered by an episode of acute vomiting and diarrhea, is reported, Computerized tomography (CT-scan) depicted small bilateral lesions in areas adjacent to the walls of the third ventricle, common location of the lesions seen in autopsy material of Wernicke's encephalopathy. Early diagnosis and treatment with vitamin B complex supplemented with intensive mnemonic and cognitive therapy led to complete recovery in a ten day period.

Determination of glutathione reductase activity in erythrocytes and whole blood as an indicator of riboflavin nutrition

Abstract: Recent developments in riboflavin statis assessment suggest the possibility of satisfactory replacement of the method based on the determination of glutathione reductase (GRe) (EC 1, 6, 4, 2) activity in erythrocytes by one on whole blood. The advantages would be the elimination of the steps of separation and washing of the erythrocytes, which may be of problematic execution under the difficult logistic conditions of field studies. In order to verify the interchangeability of the two methods, we have undertaken a comparison of the results obtained on 81 subjects. Our data show that the results of the whole blood method closely replicate those obtained on the erythrocytes and that all cases are correctly classified in terms of riboflavin status assessment. A linear regression analysis shows that the two methods overlap perfectly, with a highly significant (P less than 1%) correlation coefficient (r = 0.82). Sixty five percent of the variance of the dependent variable (CA GRsi) is accounted for by the variation of the independent variable CA GRe).

Some observations on vitamin D3 metabolism in thyrotoxicosis.

Abstract: 25 OH D3 plasma levels were measured in thyrotoxic patients and in euthyroid subjects before and after the intravenous injection of vitamin D3. In thyrotoxic subjects the transformation of injected vitamin D3 into 25 OH D3 had already begun six hours after the injection, reached a maximum between the twelfth and thirty-sixth hour and decreased thereafter. In contrast, in euthyroid healthy subjects the increase in 25 OH D3 plasma levels starts 96 hours after the vitamin D3 injection. On the basis of these data it may be estimated that hepatic hydroxylation of vitamin D3 in thyrotoxicosis is 2.5 faster than in euthyroid healthy subjects. This finding may explain the variability in 25 OH D3 plasma levels reported in thyrotoxicosis, the final value depending on degree of acceleration of the hepatic hydroxylation of vitamin D3 and on the vitamin D3 status of the organism.

Effect of vitamin A deficiency on pulmonary and hepatic protective enzymes in rat.

Abstract: Rats were fed diet with or without vitamin A for 5-6 weeks. Vitamin A deficiency had differential effect on the activities of protective enzymes in lung and liver. Superoxide dismutase activity was reduced significantly in lung, whereas remained unchanged in liver, in vitamin A deficient group. Catalase activity was reduced both in lung and liver by inducing vitamin A deficiency. On the other hand, vitamin A deficiency resulted in significant increase in the activity of glutathione peroxidase in lung and had little effect in liver. NADPH dependent lipid peroxidation, as measured by TBA products, remained unaltered, both in lung and liver in vitamin A deficient animals when compared to control group. These results suggest that vitamin A deficiency does not seem to predispose lung and liver to the injurious effects of oxygen toxicity in vivo.

Action of vitamin P like compounds on lysosomal status in hypercholesterolemic rats

Abstract: Vitamin P like compounds such as quercetin and hesperidin administered at a dose of 50 mg/Kg/day along with a hypercholesterolemic diet for three weeks significantly restored the elevated cholesterol/phospholipid ratio in rats. Both these flavonoids exerted in vivo a stabilising effect on lysosomes in rat liver which had been rendered fragile in hypercholesterolemic condition. Moreover, these compounds also possessed the stabilisation effect on lysosomes in vitro. The stabilisation effect exerted on lysosomes was found to be due to the retarded release of lysosomal acid hydrolases and not to enzyme inhibition. Such stabilisation of the lysosomes may have a beneficial role in partial amelioration of hypercholesterolemic conditions.

In vitro effect of ascorbic acid on bovine kidney alkaline phosphatase activity

Abstract: A striking decrease of bovine kidney alkaline phosphatase activity is observed in vitro when the catalytic assay is performed after preincubation of the enzyme with ascorbic acid (AA). The inhibitory effect is a function of AA concentration time and on temperature. Activity decay follows an exponential biphasic course as a function of preincubation time composed by a "fast" phase in the first half hour and by a later "slow" phase of inhibition. Both the rise in preincubation temperature and the increase of the amount of vitamin enhance the degree of inhibition. Ascorbic acid is ineffective as inhibitor when added together with the substrate, p-nitrophenyl phosphate, which in fact markedly stabilizes the enzyme even when present in unsaturating amounts.

Enzyme activities and metabolites along the kynurenine pathway in mice with Harding-Passey melanoma.

Abstract: Tryptophan metabolism has been studied in mice with Harding-Passey melanoma and in controls, after a load of 10 g/kg bw of L-tryptophan by determining ten urinary metabolites of the kynurenine pathway and some enzyme activities involved in the degradation of this aminoacid Kynurenine was the only tryptophan derivative excreted in significantly higher quantities in mice with melanoma with respect to the controls This result is in agreement with a significantly higher activity of hepatic tryptophan pyrrolase in mice with melanoma Liver kynureninase and liver and kidney kynurenine aminotransferase activities were similar in the two groups of mice These findings point to a possible role of tryptophan in the biogenesis of melanins in pathological conditions such as in melanoma

[Calcium-phosphorus changes in chronic anticonvulsant therapy: effects of the administration of 25-hydroxyvitamin D3 on secondary hyperparathyroidism].

Abstract: The present study represents a contribution to the knowledge of secondary hyperparathyroidism (SHP) in patients treated with anticonvulsant drugs (AC). In these subjects alterations of the calcium: phosphorus metabolism as rickets and osteomalacia are frequent; however literature data on SHP are scarce. Our research carried out on 29 adult patients under treatment with one or more AC for periods ranging from 9 months to 12 years confirmed that 25-OHD levels in the serum are low, especially in patients treated for longer times. The iPTH levels in the serum are increased with respect to normal controls, while blood calcium and phosphate levels are normal as are urine calcium and phosphate. The 25-OHD levels in serum present the same seasonal variations as the normal controls. The administration of 25-OHD3 (20 micrograms/day for 3 months) to 12 of these patients who had the lowest 25-OHD spring levels rendered the 25-OHD levels attain normal values. Cyclic AMP was normalized; serum and urine calcium and phosphorus and urinary hydroxyproline were not modified significantly. On the basis of the present data it is recommended that chronic AC treatment should be accompanied by long term administration of 25-OHD3 for prophylaxis and/or for treatment of SHP.

Effect of retinol on macromolecular synthesis in cultured cell lines.

Abstract: The effects of retinol on SK Mel 28 and HeLa cell lines were studied with regard to DNA and protein synthesis. It was found that vitamin A added to the culture media at a 50 microM concentration causes a 60% inhibition of DNA synthesis, that the inhibition is reversible and that this treatment does not select retinol-resistant clones. The synthesis of cytoplasmic, acid-soluble nuclear proteins and that of non-histone chromosomal proteins is inhibited as soon as the vitamin reaches the cell.

Interaction of endosulfan and dietary vitamin A on rat hepatic drug metabolising enzymes.

Abstract: The effect of interaction of Endosulfan, a chlorinated insecticide of the cyclodiene group, with dietary vitamin A on the hepatic mixed function oxidase system in rats has been studied. Endosulfan administration (ten days) significantly increased microsomal protein content and cytochrome P-450 levels, NADPH cytochrome C-reductase aminopyrine N-demethylase and aniline hydroxylase activities, with respect to control rats. Administration of vitamin A (10,000 I.U./100 g body weight) daily for ten days reduced the activity of the above mentioned enzymes, when vitamin A and endosulfan were given together, vitamin A reduced the endosulfan induced increase of microsomal proteins and cytochrome P-450 levels, the activity of NADPH cytochrome C-reductase, aminopyrine N-demethylase and aniline-hydroxylase.

Vitamin E in geriatric physiopathology

Abstract: Vitamin E can modify some of the metabolic aspects of ageing (free radicals, deficiency of protein synthesis etc.) and ameliorate the functionality of the most important body organs, of vascular and muscolo-skeletal system and metabolism. The effects of tocopherols on the glyco-lipid metabolism, as well as its hypocholesterolemic and antithrombophylic activities can positively protect the organism from the atherosclerotic damage. Vitamin E has been demonstrated to exert some effect on the maintainance of bone matrix trophysm.

Intestinal absorption of oxalate in scorbutic and ascorbic acid supplemented guinea pigs.

Abstract: Radiolabelled U-14C oxalic acid uptake was measured in the intestine of scorbutic and ascorbic acid (AA) supplemented guinea pigs. The feeding of vitamin C deficient diet to the animals for 26 days resulted in a significant fall in the ascorbic acid levels in the various tissues studied. Supplementation of vitamin C (10, 25 or 50 mg per 200 g body weight) increased ascorbic acid levels of spleen, adrenals, liver and leucocytes. The intestinal uptake of oxalate follows a passive diffusion mechanism in normally fed guinea pigs. The oxalate uptake rate was significantly increased (p less than 0.001) in the vitamin C administered group. Vitamin C depletion significantly decreased the oxalate uptake rate as compared to control animals. The changes observed in the uptake rate appear to be related with the chemical aberrations produced in the brush border membranes.

Vitamin D deficiency reduces the inotropic effect of ouabain.

Abstract: The inotropic effect of ouabain (10(-6)M) was studied "in vitro" on rat ventricle strips electrically driven at 1 Hz. The mx% increase in the force of contraction was 64.8 +/- 4.7 in the case of controls, 25.4 +/- 3.7 in the case of vitamin D-deficient rats, and 55.8 +/- 5.9 in the case of vitamin D-deficient rats pretreated with cholecalciferol (1.000 I.U./Kg/day s.c. for 5 days before heart removal). A decrease in the Ca2+ concentration from 3.1 to 1.8 mM had no effect on the basal isometric tension developed by control ventricles, it greatly reduced that developed by ventricles from rachitic rats. These results indicate that vitamin D is important for heart contractility and for the activity of cardiac glycosides, and that the hearts of rachitic animals may have difficulty in increasing their performance when solicited to do so.

The functional role of histidine and sulfhydryl groups in rat liver thiamine pyrophosphokinase.

Abstract: The functional role of histidine and sulfhydryl groups of thiamine pyrophosphokinase (ATP: thiamine pyrophosphotransferase, E.C.2.7.6.2) has been studied by the methods of photooxidation and chemical modification by diethylpyrocarbonate (DEPC) and Ellman's reagent, 5,5' - dithiobis (2 - nitrobenzoic acid) (DTNB). Histidine amino acid residues have been shown to be destroyed during photoinactivation. Titration of the protein with DEPC has established that modification of two histidine groups decreases the catalytic activity of thiamine pyrophosphokinase. Interaction of the subsequent three groups with the reagent does not affect residual activity. Substrates protect thiamine pyrophosphokinase from inactivation. Two -SH groups have been identified in a molecule of thiamine pyrophosphokinase with Ellman's reagent. Modification of only one of them results in complete loss of the enzymatic activity. Treatment of the enzyme with 8M urea has shown no differences in the amount of thiol groups of the native and denatured enzymes. Mg2+ + ATP and somewhat more weakly Mg2+ partially protect thiamine pyrophosphokinase from inhibition by DTNB. In their presence a high degree of enzyme reactivation is observed. Both histidine and sulfhydryl groups are suggested to play an important role in the catalytic mechanism of thiamine pyrophosphokinase.

Studies on the mechanism of retinoid-induced adhesion of spontaneously transformed mouse fibroblasts

Abstract: Transformed cells (Balb/c, 3T12-3), induced to increase their adhesion to the substrate by treatment with retinoic acid, display higher incorporation of (2-(3)H)-mannose into both lipids and glycoproteins than untreated controls. Stimulation of (2-(3)H)-mannose incorporation into manno-lipids is evident 8 hr after exposing the cells to retinoic acid, and stimulation of tritiated mannose incorporation into glycoproteins occurs slightly later. SDS-PAGE of (2-(3)H)-mannose labelled glycoproteins indicates that both retinoic acid and retinol treatments stimulate the incorporation of the radiolabelled sugar into a glycoprotein with subunit MW 180,000 (Gp 180) and, to a lesser extent, into other glycoproteins. 3H-leucine incorporation into a protein banding at the same position as the 3H-mannose labelled Gp 180 does not appear to be affected by retinoid treatment. A retinoic acid induced increase in the amount of Gp 180 can also be shown by lactoperoxidase catalyzed radioiodination of cultured 3T12 cells, and controlled trypsin digestion experiments indicate that Gp 180 is a component of the cell surface. On the contrary, the increased cell adhesion to the substrate induced by retinoic acid is not accompanied, in this system, by an increase in the amount of fibronectin, as judged by iodination of the cell surface components followed by SDS-PAGE.

Thiamine-binding protein from rat erythrocytes.

Abstract: A protein with thiamine-binding activity (14 nmole/mg protein) was isolated from rat red cells by affinity chromatography. Adsorbent with varying degrees of hydrophobicity containing thiamine as ligand were used for the isolation. A 2300-fold purification in a 50% overall yield was attained. The purified thiamine-binding protein is homogeneous on polyacrylamide gel electrophoresis in the presence of sodium dodecylsulfate.

Antivitamin B6 activity of L-penicillamine in Escherichia coli.

Abstract: Escherichia coli wild strain K12 and the vitamin B6 requiring mutant strain KG980 were compared with respect to the growth inhibition by L-penicillamine and the reversal of inhibition with pyridoxine. The growth of KG980 was much more severely inhibited than that of K12 by relatively low concentrations of L-penicillamine, when KG980 was grown with a usually sufficient concentration of pyridoxine. The following findings indicated that this was because L-penicillamine caused vitamin B6 deficiency in KG980; (a) addition of excess pyridoxine significantly reversed the inhibition, (b) comparison of the growth with various concentrations of pyridoxine showed that the vitamin requirement became higher upon addition of L-penicillamine. Examination of cellular vitamin B6 compounds showed that pyridoxal 5'-phosphate was markedly decreased when L-penicillamine was present, in agreement with the probable reaction of the inhibitor with the coenzyme. On the other hand, the growth inhibition of K12 appeared independent of vitamin B6 deficiency, and the cellular pyridoxal 5,-phosphate was found not to be markedly reduced by the presence of L-penicillamine, while the total of vitamin B6 compounds, probably including the product formed by the coenzyme and the inhibitor, increased clearly. The results, therefore, suggest that the wild strain of E. coli can avoid the deficiency of vitamin B6 by enhancing its biosynthesis, although L-penicillamine acts as an antivitamin B6.

[Effect of 13-cis-retinoic acid (Ro 4-3780) in the therapy of severe cystic acne].

Abstract: Five subjects with serious cystic acne, two of which were also affected by hydrosadenitis, were examined during a treatment with 13-cis-retinoic acid. The drug was given at decreasing doses: 0.9 mg/kg body weight for a period of six weeks, followed by a second six weeks period at 0.6 mg/kg and lastly by another 9 months period at 0.3 mg/kg. The patients had a good response to the treatment with a rapid reduction of the number and of the severity of the acneic lesions, with the only exception of one subject who had a relapse at the 18th week. This study, limited to a small number of patients, suggest that 13-cis-retinoic acid may be used in severe cystic acne with a higher dosage in the presence of complicating hydrosadenitis.