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Query: UMLS:C0240066 (iron deficiency)
 7,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of iron deficiency on a number or iron containing enzymes in rat liver has been examined. In addition, 6-phosphogluconate dehydrogenase and glucose 6-phosphate dehydrogenase have been assayed. Of the mitochondrial electron transport reactions only succinate-cytochrome C reductase activity was decreased in iron deficient animals. Microsomal reductase enzymes associated with the NADPH-oxidase system were also markedly decreased although cytochrome P450 concentrations were unaffected. Both 6-phosphogluconate dehydrogenase and glucose 6-phosphate dehydrogenase were reduced in young iron deficient rats but the former had returned to control levels at the age of 14 weeks.
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PMID:The effects of iron deficiency on rat liver enzymes. 17 99

Four groups of weanling male rats were fed one of three iron-deficient diets (6, 18 and 23 mg iron/kg diet) or a normal iron-containing diet (41 mg iron/kg diet) for 30 d. The effects of the diets on various iron status parameters were determined and four enzymes were assayed: cytochrome P450 (P450) and NADPH cytochrome P450 reductase (P450-RED) in liver and intestine microsomes, and glucose-6-phosphate dehydrogenase (G6P-DH) and 6-phosphogluconate dehydrogenase (6PG-DH) in liver, intestine and erythrocyte cytosol. Rats fed 6 mg iron/kg diet were severely anemic, whereas rats fed 18 or 23 mg iron/kg diet were moderately or mildly iron-deficient, as shown by their hemoglobin levels, hematocrit, red blood cell parameters, erythrocyte protoporphyrin and liver iron stores. P450 concentration and P450-RED activity in liver were unaffected by iron deficiency, but P450 concentration was markedly lower in the intestine of the three iron-deficient groups than in the controls. Activities of G6P-DH and 6PG-DH were not impaired in liver or intestine, except that liver 6PG-DH activity of severely anemic rats was less than that of control rats. However, severe and moderate iron deprivation resulted in a stimulation of G6P-DH and 6PG-DH activities per million erythrocytes. These results demonstrate that even moderate iron deficiency may alter fundamental enzymatic systems intervening in drug metabolism and in the pentose phosphate pathway.
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PMID:Effects of different degrees of iron deficiency on cytochrome P450 complex and pentose phosphate pathway dehydrogenases in the rat. 249 36

Male Wistar rats kept on the iron-deficient diet for 7-71/2 weeks showed an increase in the content of cytochromes P450 and b5 in liver microsomes that was accompanied by the elevated rate of N-demethylation of amidopyrin and dimethylalanine (type I substrates), and by that of p-hydroxylation of aniline (type II substrate). The changes described wee observed in the presence of a 20-25% reduction in the hemoglobin content in the blood of experimental animals. Administration to rats of phenobarbital (100 mg per kg mass daily for 3 days) caused an induction of the monooxygenase system of the liver endoplasmic reticulum. However under the conditions of iron deficiency in the diet the degree of cytochrome P450 induction and that of the reaction rate of N-demethylation in microsomes were slightly less than under the full-value diet.
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PMID:[Effect of dietary iron deficiency on the activity of the monooxygenase system of rat liver microsomes and its induction by phenobarbital]. 711 97

Male Fischer rats were maintained for a period of 17 weeks on an iron-deficient diet along with suitable controls. The effect of long term deprivation of iron on xenobiotic metabolism was studied by the activities of various drug metabolising enzymes in both liver as well as extra-hepatic tissues like lungs, kidneys and intestinal mucosa (I.M.). The results show that among the Phase I (activating) enzymes, the hepatic activities of benzo(a)pyrene hydroxylase (AHH) and microsomal epoxide hydrolase (mEH) are significantly reduced in iron deficiency. The other parameters of the activating system, namely cytochrome P450, aminopyrene demethylase (ADM) and aniline hydroxylase (AH), are not altered. Of the two Phase II (conjugating) enzymes studied, only uridine diphospho glucuronyl transferase (UDPGT) is found to be depressed, but not glutathione S-transferase (GST) in liver in iron deficiency. Activities of Phase I enzymes are markedly lowered in extra-hepatic tissues compared to liver; such depression is not observed in conjugating enzymes. Iron deficiency does not seem to make much impact on the enzyme activities of extra-hepatic tissues. Overall, the hepatic results suggest a defect in detoxification mechanisms in iron deficiency. Such impairment may very well predispose an iron-deficient host to an increased risk of carcinogenesis.
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PMID:Effect of long term iron deficiency on the activities of hepatic and extra-hepatic drug metabolising enzymes in Fischer rats. 785 40

Iron is regarded as one of the most important nutriments, and many diseases are related to iron deficiency or its overload. Approximately 70% of iron in the body is located in heme, functioning as hemoglobin, myoglobin, and cytochrome P450. Iron itself also has many catalytic functions through the iron-sulfa cluster. It is believed that iron and/or heme plays significant roles in regulation of genes, however, little about the mechanism has been elucidated. Recently, not only iron but also heme has been identified as important regulators of gene activation via oxygen sensing. For example, iron controls the oxygen response of HIF-1 activity by two mechanisms; in cytosol, the half life of HIF-1 alpha is determined by hydroxylation of Pro, and transcriptional activity of HIF1 alpha in nuclei is disturbed by hydroxylation of Asn. Hemoproteins in prokaryotes such as FixL, Dos, and HemAT were found to be oxygen sensors, however, little has been reported in eukaryotes. Our finding on Bach1 seems to be the first report of heme and oxygen-mediated regulation of genes in vertebrates. Understanding of these newly identified mechanisms in iron- and heme-controlled genes is essential in the field of nutritional science. We therefore summarize here the recent findings indicating mechanisms of iron as transcriptional regulators.
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PMID:[Molecular biology of iron in nutritional science]. 1280 62

Iron regulatory protein 2 coordinates the cellular regulation of iron metabolism by binding to iron-responsive elements in mRNA. The protein is synthesized constitutively but is rapidly degraded when iron stores are replete. The mechanisms that prevent degradation during iron deficiency or promote degradation during iron sufficiency are not delineated. Iron regulatory protein 2 contains a domain not present in the closely related iron regulatory protein 1, and we found that this domain binds heme with high affinity. A cysteine within the domain is axially liganded to the heme, as occurs in cytochrome P450. The protein-bound heme reacts with molecular oxygen to mediate the oxidation of cysteine, including beta-elimination of the sulfur to yield alanine. This covalent modification may thus mark the protein molecule for degradation by the proteasome system, providing another mechanism by which heme can regulate the level of iron regulatory protein 2.
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PMID:Identification of a heme-sensing domain in iron regulatory protein 2. 1531 13

Iron deficiency is among the most common nutritional disorders in plants. Low iron supply causes decreased root growth and even plant death. However, there are no reports about the specific pathways that lead Fe-deficient roots to senescence and death. To investigate the molecular mechanisms that regulate rice roots response to Fe-deficiency, rice seedlings were grown for 3, 6 and 9 days in the presence or absence of Fe. Sequences of 28 induced genes in rice roots under Fe-deficiency were identified by representational difference analysis (RDA). About 40% of these sequences have been previously reported as senescence-related. Differential expression of selected genes was confirmed by semi-quantitative RT-PCR analysis. Classical senescence-related sequences, such as MYB and WRKY transcription factors, cysteine protease, ubiquitin-conjugating enzyme, lipid transfer protein, fatty acid hydroxylase, beta-glucosidase and cytochrome P450 oxydoreductase were identified. Fe-deficiency also resulted in decreased dry weight, increased lipid peroxidation (detected by TBA and histochemical methods) as well as evident membrane damage in Fe-deficient roots. Taken together, the results indicate that Fe-deficiency in roots is linked to typical senescence pathways, associated with lipid peroxidation.
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PMID:Increased senescence-associated gene expression and lipid peroxidation induced by iron deficiency in rice roots. 1771 72

Accumulating evidence, including experiments using cytochrome P450 1a2 (Cyp1a2) gene knock-out mice (Cyp1a2(-/-)), indicates that the development of chemically induced porphyria requires the expression of CYP1A2. It has also been demonstrated that iron enhances and expedites the development of experimental uroporphyria, but that iron alone without CYP1A2 expression, as in Cyp1a2(-/-) mice, does not cause uroporphyria. The role of iron in the development of porphyria has not been elucidated. We examined the in vivo effect of iron deficiency on hepatic URO accumulation in experimental porphyria. Mice were fed diets containing low (iron-deficient diet (IDD), 8.5 mg iron/kg) or normal (normal diet (ND), 213.7 mg iron/kg) levels of iron. They were treated with 3-methylcholanthrene (MC), an archetypal inducer of CYP1A, and 5-aminolevulinate (ALA), precursors of porphyrin and heme. We found that uroporphyrin (URO) levels and uroporphyrinogen oxidation (UROX) activity were markedly increased in ND mice treated with MC and ALA, while the levels were not raised in IDD mice with the same treatments. CYP1A2 levels and methoxyresorufin O-demethylase (MROD) activities, the CYP1A2-mediated reaction, were markedly induced in the livers of both ND and IDD mice treated with MC and ALA. UROX activity, supposedly a CYP1A2-dependent activity, was not enhanced in iron-deficient mice in spite of the fact of induction of CYP1A2. We showed that a sufficient level of iron is essential for the development of porphyria and UROX activity.
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PMID:Absolute requirement for iron in the development of chemically induced uroporphyria in mice treated with 3-methylcholanthrene and 5-aminolevulinate. 1895 44

Under conditions of reduced iron availability, most frequent in calcareous soils, plants induce the "Fe Deficiency Response" to improve root Fe uptake. The transcription factor FIT is essential for such a response in strategy I plants, such as Arabidopsis thaliana. From microarray analysis of Arabidopsis roots, it is known that three different cytochrome P450 genes, CYP82C4, CYP82C3 and CYP71B5 are up-regulated under Fe deficiency through a FIT-dependent pathway. We show that, out of these three P450 genes, only CYP82C4 strongly correlates with genes involved in metal uptake/transport. The CYP82C4 promoter, unlike those of CYP82C3 and CYP71B5, contains several IDE1-like sequences (iron deficiency-responsive element) as well as an RY element. While confirming that the CYP82C4 transcript accumulates in Fe-deficient Arabidopsis seedlings, with circadian fluctuations in a light-dependent way, we also demonstrate that such accumulation is suppressed under Fe excess. Full suppression of CYP82C4 expression, as observed in the atc82c4-1 KO mutant, is associated with longer roots at the seedling stage. We propose that CYP82C4 is involved in the early Fe deficiency response, possibly through an IDE1-like mediated pathway.
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PMID:Arabidopsis CYP82C4 expression is dependent on Fe availability and circadian rhythm, and correlates with genes involved in the early Fe deficiency response. 2131 74

Long-term treatment with proton pump inhibitors (PPI) is becoming more prevalent. Although they are well tolerated in the short term, serious concerns about long-term use have arisen. Recent data suggest that the latter is associated with an increased risk for osteoporotic fracture (especially vertebral), Clostridium difficile infection and rebound acid hypersecretion after treatment discontinuation. Acute interstitial nephritis is rare but may progress to chronic renal failure. An increased risk of community-acquired pneumonia has not been established in the general population and seems limited to the most vulnerable patients. Consistent data are still missing to correctly assess the risk of iron deficiency, vitamin B12 deficiency or hypomagnesaemia and the risk of digestive malignant diseases, despite the pathophysiological basis that exists concerning gastric malignancy. Many drug interactions can occur on long-term treatment, including some that imply the cytochrome P450 enzymes. Finally, the risk-benefit balance for a chronic PPI use in children seems unfavorable in most cases.
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PMID:[Adverse effects of proton pump inhibitors: should we worry about long-term exposure?]. 2250 39


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