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At least 19 recordsLinked to original sources
PubMed1986

Metabolism of 3H-proline in riboflavin deficiency.

Riboflavin deficiency and food restriction were associated with greater solubility and lesser total and insoluble collagen concentration in rat skin. Studies using 3H-proline suggest that the lower collagen concentration under these conditions could be due to a decrease in synthesis as well as slow maturation of collagen. The mechanisms underlying defective cross-link formation appear to be different in food-restricted and riboflavin-deficient rats. Half-life of soluble collagen was not affected in riboflavin deficiency, but it was slightly shorter in food-restricted weight-matched animals.

Animals↗
PubMedDate not supplied

Embryonic death in mink due to riboflavin deficiency.

Riboflavin deficiency has been produced experimentally in mink by adding to the feed 10--20 mg galactoflavin--anti-B2 vitamin--per animal daily during the pregnancy. The experiment included 44 standard female mink (Table II). Riboflavin deficiency led to embryonic death; none of the mated females in the deficient group delivered kits. At the expected time of birth, six of the females were subjected to uterectomy or investigative laparatomy, which showed remnants of embryos that were mostly decomposed (Figs. 1 and 2). In a parallel group, four of six females on the same diet with the same doses of galactoflavin, but with 50--100 mg riboflavin added daily, delivered normal litters (Table II). Five standard male mink were placed on the same experimental diet supplemented with 30 mg galactoflavin per animal daily from 15/12 to 18/3. The fertility of these males was not influenced in a negative way.

Animals↗
PubMed1993

Effects of riboflavin deficiency and riboflavin administration on carcinogen-DNA binding.

A study was conducted to assess the effects of riboflavin deficiency and riboflavin supplementation on carcinogen-DNA binding. After 12 wk on a riboflavin-sufficient or a riboflavin-deficient diet male Wistar rats were administered 3H-labelled benzo[a]pyrene (BP) ip. [3H]BP was given either at a uniform dose of 450 muCi/rat irrespective of body weight or at a dose adjusted to body weight. After 17 hr the animals were killed, various organs were dissected and the level of [3H]BP bound to DNA was quantified in organs that are known to be the seats of drug metabolism (i.e. the liver, lungs and intestinal mucosa). In a separate experiment, the effect of riboflavin supplementation on BP-DNA binding was also investigated. When [3H]BP was administered at 450 microCi/rat, BP-DNA binding was markedly increased in the livers and intestinal mucosae of the pair-fed and deficient groups compared with controls. With the administration of [3H]BP adjusted to body weight, no differences in BP-DNA binding between groups were observed in any tissue. However, on administration of riboflavin there was a decrease in the level of [3H]BP bound to DNA in almost all tissues, especially in the lungs, where the reduction was significant. The results suggest that undernutrition/riboflavin deficiency may increase the risk of carcinogenesis by way of an increase in carcinogen binding, which however can be reversed by riboflavin supplementation.

Animals↗
PubMed1980

Hepatic drug metabolism during ethanol ingestion in riboflavin deficient rats.

Riboflavin deficiency was induced by feeding rats a riboflavin-deficient diet for 1 month. In order to find out if there are any combined effects of ethanol and riboflavin deficiency on drug metabolism, a group of riboflavin-deficient rats were also given ethanol in their drinking water. At the end of the feeding period, hepatic drug-metabolizing enzyme activities were determined. The hepatic phospholipid and protein contents were the same in rats receiving a standard diet and in those on a riboflavin-deficient diet. However, ethanol ingestion in both groups enhanced significantly the phospholipid content. Ethanol ingestion also markedly enhanced the hepatic cytochrome P-450 concentration in rats fed either a standard or riboflavin-deficient diet. Ethoxycoumarin O-deethylase activity was significantly lower in riboflavin-deficient rat livers than in those of the controls. In both groups ethanol ingestion nearly doubled the activities. Aryl hydrocarbon hydroxylase activity was also significantly decreased during riboflavin deficiency. However, ethanol administration did not change the activities of this enzyme. UDP glucuronosyltransferase activity was slightly lower in riboflavin-deficient rat livers than in those fed a standard diet. No significant decrease was found in the epoxide hydrase activity in the riboflavin-deficient rats. However, the riboflavin-deficient rats had enhanced activity after the ethanol ingestion.

Animals↗
PubMed1993

Comparison of changes in the uptake and mucosal processing of iron in riboflavin-deficient rats.

Riboflavin deficiency in rats resulted in a reduction in the transfer of 59Fe from an intragastric dose to plasma compared to age-matched or weight-matched controls. The uptake of iron by brush-border membrane vesicles made from intestinal mucosa of riboflavin-deficient rats was much less than identically-prepared vesicles from control groups. Although the mucosal content of 59Fe was smaller in riboflavin-deficient rats thirty minutes after dosing, the relative distribution of 59Fe between the mucosal iron-binding proteins, ferritin and transferrin, was not changed compared to the control groups. These studies suggest that the impairment in iron absorption in riboflavin deficiency is primarily the result of a reduced uptake of iron into the mucosal cell and not a redistribution of iron between iron-binding proteins inside the mucosal cell.

Animals↗
PubMed1996

Sudden death of chicken embryos with hereditary riboflavin deficiency.

Riboflavin-binding protein (RfBP) mediates the deposition of riboflavin during the formation of eggs in birds. Hens of a strain of Single-Comb White Leghorn chickens, which are genetically unable to produce RfBP, lay eggs containing insufficient riboflavin to sustain embryogenesis beyond 13 or 14 d of incubation. Embryos in these eggs grow normally until the day of death, and their heart rate is normal to within an hour of death. The effects of riboflavin-deficiency first appear after d 10 of incubation when embryos become severely hypoglycemic and begin to accumulate intermediates of fatty acid oxidation. Although the activities of flavin-dependent enzymes are reduced generally, the 80% reduction in the activity of medium-chain acyl-CoA dehydrogenase further suggests that the major metabolic consequence of riboflavin deficiency is a severe impairment of fatty acid oxidation. The riboflavin-deficient strain provides numerous insights into the metabolism of normal hens and chicken embryos and may be a useful model for sudden death syndromes in humans.

Acyl-CoA Dehydrogenases↗
PubMed1990

Riboflavin deficiency in cultured rat hepatoma cells: a model for studying the hepatic effects of riboflavin deficiency.

The acyl-CoA dehydrogenases are a family of mitochondrial flavoenzymes required for fatty acid beta-oxidation and branched-chain amino acid degradation. The hepatic activity of these enzymes, particularly the short-chain acyl-coenzyme A (CoA) dehydrogenase, is markedly decreased in riboflavin deficient rats. We now report that the in vivo effects of riboflavin deficiency on the beta-oxidation enzymes of this group are reproduced in FAO rat hepatoma cells cultured in riboflavin-deficient medium. Although it has been long known that hepatic short-chain acyl-CoA dehydrogenase activity is the most severely affected of the straight-chain specific enzymes in riboflavin deficiency, the mechanism by which its activity is decreased has not been reported. We have used this new cell culture system to characterize further this mechanism. Whole cell extracts from riboflavin-deficient and control cells were subjected to analysis by denaturing polyacrylamide gel electrophoresis. The contents of the gels were then electroblotted onto nitrocellulose filters and probed with short-chain acyl-CoA dehydrogenase-specific antiserum. The relative abundance of enzyme antigen was estimated autoradiographically. Our findings indicate that short-chain acyl-CoA dehydrogenase activity changes in parallel with its antigen, suggesting that riboflavin deprivation does not affect the activity of individual enzyme molecules. Further, no evidence of extramitochondrial enzyme precursor was found on the blots, making unlikely a significant block in the mitochondrial uptake process. These findings suggest that changes in short-chain acyl-CoA dehydrogenase activity in riboflavin deficiency result from either increased synthesis or decreased degradation of the enzyme.

Acyl-CoA Dehydrogenase↗
PubMed1981

Cataracts and riboflavin deficiency.

Lenticular reduced glutathione, diminished in all forms fo human cataract, requires flavin adenine dinucleotide as a coenzyme for glutathione reductase. Deficiency of riboflavin, a precursor of flavin adenine dinucleotide, has been believed by some to be associated with cataract formation. We evaluated the riboflavin nutritional status of healthy young adults, presenile and senile cataract patients, and young and older patients with clear lenses. We found no evidence of an association between riboflavin deficiency and early cataract formation, either idiopathic or secondary. Older cataract patients had more riboflavin deficiency. An absence of riboflavin deficiency was found in our older patients with clear lenses. The degree of riboflavin deficiency encountered in the general population does not appear to be cataractogenic.

Adult↗
PubMed1991

Metabolism of deuterium-labeled nonanoic acids in the riboflavin-deficient rat model of multiple acyl-CoA dehydrogenase deficiency.

Riboflavin-deficient rats are used to study the metabolism of deuterium-labeled nonanoic acids under conditions mimicking the human disorder of multiple acyl-CoA dehydrogenase deficiency in which large amounts of ethyl-malonic, glutaric, adipic, suberic, 4-octenedioic, sebacic and 4-decenedioic acids are excreted. Both control and deficient rats convert the nonanoic acids to labeled azelaic and pimelic acids. The labeling pattern in pimelic acid is consistent with the omega-oxidation of nonanoic acids to azelaic acid followed by beta-oxidation to pimelic acid.

Acyl-CoA Dehydrogenases↗
PubMed1988

Transcriptional regulation of carnitine palmitoyltransferase synthesis in riboflavin deficiency in rats.

Riboflavin deficiency leads to depressed mitochondrial fatty acid oxidation rates but increased activity of carnitine palmitoyltransferase (CPT). Starvation leads to increased CPT activity in ad libitum-fed, riboflavin-supplemented rats. The present studies examined the mechanism of the increase in CPT activity in riboflavin deficiency and whether it was additive to that seen in starvation. Rats were divided into three groups initially: riboflavin-sufficient, ad libitum-fed; riboflavin-deficient, ad libitum-fed; and pair-fed. These groups were subdivided after 5 wk into fed and 24- and 48-h starved groups. When riboflavin-deficient rats were starved for 24 or 48 h, there was only a 30-40% increase in hepatic CPT activity, in contrast to the ad libitum-fed, riboflavin-supplemented rats, in which activity increased twofold. CPT activity of pair-fed rats was similar to that of controls in the fed state and did not increase significantly with starvation. CPT translation, mRNA levels and transcription rates correlated with CPT activity, as did immunoreactive CPT. Concurrently, hepatic ketone production and plasma beta-hydroxybutyrate concentration increased during starvation in the control and pair-fed but not in the riboflavin-deficient rats. The results indicate that increased CPT activity in riboflavin deficiency and starvation results at least in part from increased synthesis. Furthermore, the data support previous work suggesting that the block in fatty acid oxidation occurs in the beta-oxidation pathway at the level of acyl-CoA dehydrogenases.

Acyltransferases↗
PubMed1991

Glutathione and related indices in rat lenses, liver and red cells during riboflavin deficiency and its correction.

Biochemical changes in lenses and at other sites in adult rats were investigated during the induction and correction of riboflavin deficiency. Riboflavin deficient (D), 1-day-repleted (R1), 2-days-repleted (R2), 16-days-repleted (R3), food-restricted, weight-matched controls (CFR) and ad libitum-fed controls (CAL) were compared. Activation coefficients of erythrocyte and lens glutathione reductase, which became abnormal in the deficient (D) animals, were corrected to varying extents in the repleted (R) groups. Hepatic flavin concentrations were lowered in the groups with raised glutathione. Inter-group differences in hepatic glutathione concentrations were not simply related to tissue flavin depletion or its reversal, but were complicated by changes in liver: body-weight ratios. Inter-group differences in lenticular glutathione levels were very small. In both liver and lens, sorbitol concentrations were lowest in group R3 and highest in groups D, R1 and R2. Lens ascorbate levels and the lens enzymes, aldose reductase, sorbitol dehydrogenase, glutathione peroxidase and superoxide dismutase, were not significantly affected by diet. Thiobarbituric acid-reactive substances were increased in riboflavin-deficient rat lenses but were lowered in riboflavin-deficient plasma samples. The results suggest overall that while riboflavin deficiency may affect certain biochemical indices, such as sorbitol and thiobarbituric-reactive substances, in the lens and other tissues, these changes are not the result of lowered glutathione levels. They also clearly demonstrate the importance of inanition as a confounding factor in the interpretation of changes resulting from riboflavin deficiency in experimental animals.

Animals↗
PubMed1990

Urinary riboflavin excretion after a load test in rural China as a measure of possible riboflavin deficiency.

Urinary excretion of riboflavin was measured in 3318 adults 4 h after an oral dose of riboflavin. Male and female subjects aged 35-64 years were selected from 65 mostly rural counties located in 24 provinces of China. Counties were selected to represent a range of seven of the most prevalent cancer mortality rates in China and within counties households were selected at random. Urinary riboflavin excretion levels after a load test, erythrocyte glutathione reductase activity coefficients (EGR-AC), dietary riboflavin intakes, and a large number of other biochemical, dietary, and environmental parameters were measured. Mean dietary intake of riboflavin was 75 per cent of the Chinese recommended dietary allowances (CRDA). Mean meat intake per reference man was very low (26.4 +/- 23.7 g/d) in comparison to Western standards and milk was not consumed at all in most counties. Mean EGR activity coefficients measured on 'blood pools' for both males (1.47 +/- 0.14) and females (1.48 +/- 0.16) indicated that more than two-thirds of the population surveyed was in the medium or high risk category of riboflavin deficiency. Using current reference standards of less than 1.4 mg for 4-h urinary excretion of riboflavin after a 5 mg load, more than 70 per cent of the individuals examined exhibited low levels usually associated with high risk of riboflavin deficiency. In view of the lack of specificity for clinical indications of riboflavin deficiency and the tentative validity of the present CRDA, the interpretation of the data is problematic. We suggest that the present CRDA for this vitamin is set too high and requires critical review and possibly some revision.

Administration, Oral↗
PubMed1980

L-gulonolactone oxidase activity and vitamin C status in riboflavin-deficient rats.

The effect of riboflavin deficiency on the activity of L-gulonolactone oxidase [L-gulono-gamma-lactone: oxygen 2-oxidoreductase, EC 1.1.3.8] and on vitamin C status was studied. A marked decrease in the specific activity of L-gulonolactone oxidase was observed in the liver microsomes isolated from riboflavin-deficient rats: the specific activity was approx. one-third of that in the microsomes isolated from control rats. The L-ascorbic acid content in the liver of the riboflavin-deficient rats was approx. one-half of that in the liver of the control rats. It seems that the rate of production of L-ascorbic acid in the riboflavin-deficient rats is limited by the decreased level of L-gulonolactone oxidase activity. Immunotitration using rabbit antiserum directed to L-gulonolactone oxidase revealed that a substantial amount of an inactive form of this enzyme is present in the liver microsomes of the riboflavin-deficient rats. L-Gulonolactone oxidase activity in the microsomes of these rats increased by approx. 35% upon addition of FAD, but it was slightly decreased by the addition of FMN or riboflavin. These results indicate that the liver microsomes of the riboflavin-deficient rats contain a protein which exhibits L-gulonolactone oxidase activity upon addition of Fad.

Animals↗
PubMed1985

Hepatic peroxisomal and mitochondrial fatty acid oxidation in the riboflavin-deficient rat.

The effects of riboflavin deficiency on hepatic peroxisomal and mitochondrial palmitoyl-CoA oxidation were examined in weanling Wistar-strain male rats. The specific activities of peroxisomal catalase and palmitoyl-CoA-dependent NAD+ reduction were not affected by up to 10 weeks of riboflavin deficiency. In contrast, the specific activity of mitochondrial carnitine-dependent palmitoyl-CoA oxidation was depressed by 75% at 10 weeks of deficiency. The amount of peroxisomal protein per g of liver was not affected by riboflavin deficiency, whereas, expressed per liver, both riboflavin-deficient and pair-fed controls showed decreased peroxisomal protein compared with controls fed ad libitum. Hepatic mitochondria, but not peroxisomes, were sensitive to riboflavin deficiency.

Acyl Coenzyme A↗
PubMedDate not supplied

Alterations in the lenticular proteins of rats on riboflavin deficient diet.

Effect of feeding riboflavin deficient diet to rats on lens protein composition was investigated. Total proteins and profile of soluble and insoluble proteins in lenses from rats fed on a riboflavin deficient diet for seven weeks were found to be similar to that of the vitamin supplemented diet. Distribution of high molecular weight protein (above 4 X 10(6) daltons) isolated from the 9,900 g supernatant fraction was found to be significantly higher and gamma crystallin was significantly lower in riboflavin deficient group as compared to the normal lenses. However, the distribution of alpha and beta crystallins was not affected. Gel electrophoresis in sodium dodecyl sulfate of soluble lens proteins from riboflavin deficient animals had lower proportions of polypeptide species with molecular weight above 40,000 daltons while insoluble protein fraction had higher proportions of these polypeptide species as compared to control rats. These data suggest that the composition of lens proteins is altered in riboflavin deficiency.

Animals↗
PubMed1987

Acyl-CoA dehydrogenase activity in the riboflavin-deficient rat. Effects of starvation.

Riboflavin deficiency in weanling rats causes a metabolic disorder characterized by failure to oxidize fatty acids. The disorder is similar to that seen in several human diseases, some of which are responsive to pharmacological doses of riboflavin. Previous analysis of the riboflavin-deficient rat has shown that the failure of fatty acid oxidation is due to a decrease in the activity of the acyl-CoA dehydrogenases of beta-oxidation. The activity of these flavoenzymes in liver rapidly decreases when a riboflavin-deficient diet is initiated. The objectives of these experiments were to analyse the effects of starvation on liver mitochondria isolated from the riboflavin-deficient rat. Our studies show that the decreased mitochondrial fatty acid oxidation induced by riboflavin deficiency is partially reversed by starvation. The extent of this reversal is proportional to the duration of starvation. The starvation-associated increase in fatty acid oxidation is mediated by an increase in the mitochondrial short-chain acyl-CoA dehydrogenase activity. The activity of this enzyme is increased such that the ratio of short-chain acyl-CoA dehydrogenase apoenzyme to holoenzyme does not change. We conclude that short-chain acyl-CoA dehydrogenase activity is limiting for fatty acid oxidation when its activity falls below a critical point. The increased mitochondrial specific activity of short-chain acyl-CoA dehydrogenase during starvation may result from an increased availability of flavin coenzyme or an increase in enzyme catalytic efficiency.

Acyl-CoA Dehydrogenase↗
PubMed1982

Lipid metabolism in riboflavin-deficient rats. 1. Effect of dietary lipids on riboflavin status and fatty acid profiles.

1. The increase in activation coefficient (stimulated: basal activity) of erythrocyte NAD(P)H2: glutathione oxidoreductase (EC 1.6.4.2) and reduction in hepatic flavin concentration which occurred in riboflavin-deficient weanling rats were not markedly or consistently affected by differences in the concentration of lipid in the diet nor by differences in the total proportion of saturated or polyunsaturated fatty acids in the dietary lipid. 2. Their gain in body-weight was, however, reduced when the dietary lipid concentration was increased from 30 to 200 g/kg and liver: body-weight and hepatic triglyceride content were correspondingly increased, suggesting a functionally-deleterious effect of high fat intake in the deficient animals. This was especially severe when the diets contained cottonseed oil, which appeared to be toxic for the deficient animals. 3. Comparisons between fatty acid profiles of hepatic phospholipids of deficient, pair-fed and ad lib,-fed control animals indicated that the increase in proportion of 18:2 omega 6 and the decrease in proportion of 20:4 omega 6 observed in deficient animals were due specifically to riboflavin deficiency, whereas certain other changes were probably caused by inanition. The changes in 18:2 omega 6 and 20:4 omega 6 were observed at both low and high levels of lipid intake and at both low and high levels of dietary lipid polyunsaturation. Similar changes in fatty acid profiles were observed in renal, erythrocyte membrane, and plasma phospholipids, but were not seen in cardiac phospholipids, 4. A consistent increase in proportion of 18:2 omega 6 was also observed in the hepatic triglycerides, together with a decrease in proportion of 16:0. 5. It is concluded that acute riboflavin deficiency affects lipid metabolism in a characteristic manner, probably by interfering with beta-oxidation of fatty acids, but that diets of high lipid content do not significantly increase the extent of flavin depletion.

Animals↗