Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Deferoxamine has been proposed as a potentially important therapy for individuals with NIDDM and mild elevations in serum ferritin. Previously, iron chelation therapy with intravenous deferoxamine over a 5-13-wk period has been reported to normalize serum ferritin and markedly improve glycemic control. To confirm these results and to study potential beneficial effects of deferoxamine on insulin secretion, 9 individuals with NIDDM and elevated serum ferritin levels were treated twice weekly with deferoxamine infusion, following a previously described protocol. Although 8 of 9 subjects achieved normal or near-normal serum ferritin values after deferoxamine therapy, we found little evidence that it produced beneficial effects on glycemic control. Fasting glucose levels pre- and post-deferoxamine therapy were unchanged (11.6 +/- 1.2 and 11.3 +/- 1.5 mM, respectively, P = 0.80). GHb levels declined slightly after deferoxamine therapy (9.3 +/- 0.7 vs. 8.8 +/- 0.7%, P < 0.05); however, this effect was small and was not associated with elimination of or even substantial reduction in insulin or oral hypoglycemic therapy. Deferoxamine therapy did not significantly alter fasting insulin or C-peptide levels, nor stimulated insulin or C-peptide responses to intravenous arginine or glucose. During follow-up studies 1.5-8 mo after deferoxamine therapy, serum ferritin levels again were elevated in 5 of 8 subjects who showed an initial response. Thus, although deferoxamine therapy reduced serum ferritin levels in our subjects, we were unable to confirm a previous report that this effect was associated with any meaningful improvement in glycemic control or insulin secretion.
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PMID:No effect of deferoxamine therapy on glucose homeostasis and insulin secretion in individuals with NIDDM and elevated serum ferritin. 845 4

We have recently identified ferritin as a cellular protein particle whose synthesis is stimulated in mouse or human cells infected by the picornavirus Mengo. Immunoprecipitation of the particle from infected murine L929 cells showed a 4- and 6-fold increase in the intracellular concentrations of H and L apoferritin subunits, respectively. This differential expression altered the H/L subunit ratio from 3.0 in uninfected cells to 2.2 in Mengo virus-infected cells. The induction is not due to an increase in transcription of the apoferritin L and H genes, nor is it due to an increase in stability of the apoferritin mRNAs. At the level of translation, the iron regulatory protein (IRP) remained intact, with similar amounts being detected in uninfected and infected cells. The Mengo virus RNA genome does not compete with the iron regulatory element (IRE) for the binding of IRP, and sequence analysis confirmed that there are no IREs in the virus RNA. The IRE binding activity of IRP in infected cells decreased approximately 30% compared with uninfected cells. The decrease in binding activity could be overcome by the addition of Desferal (deferoxamine mesylate; CIBA) an intracellular iron chelator, which suggests that virus infection causes an increase in intracellular free iron. Electron paramagnetic resonance (EPR) studies have confirmed the increase in free iron in Mengo virus infected cells. The permeability of cells for iron does not change in virus infected cells, suggesting that the induction of ferritin by Mengo virus is due to a change in the form of intracellular iron from a bound to a free state.
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PMID:Induction of ferritin synthesis in cells infected with Mengo virus. 862 69

Iron regulatory proteins (IRPs) are RNA-binding proteins that post-transcriptionally regulate synthesis of iron uptake (transferrin receptor) and storage (ferritin) proteins. Our previous work demonstrating that IRP1 is phosphorylated by protein kinase C supported the hypothesis that factors in addition to iron modulate IRP function. We have investigated changes in activity and expression of both IRP1 and IRP2 during phorbol 12-myristate 13-acetate (PMA)-induced differentiation of HL-60 cells. In contrast to IRP1, IRP2 was highly phosphorylated in untreated cells. PMA stimulated phosphorylation of IRP1 and IRP2 by at least 2-3-fold without affecting incorporation of [35S]methionine into the proteins. IRP1 and IRP2 isolated from PMA-treated cells displayed different phosphopeptides. Phosphorylation of IRPs was associated with a 2-fold increase in high affinity RNA binding activity without altering KD, and this was accompanied by a 50% increase in transferrin receptor mRNA abundance. PMA acted on a latent pool of binding activity that is present in a nonaconitase oxidized form and is largely composed of a stable but inactive species of IRP2. Desferal and hemin modulated iron-responsive element binding activity in HL-60 cells without affecting the phosphorylation state of IRP1. Hemin appeared to reduce the abundance of phosphorylated IRP2. Thus, multiple factors affect the function of both IRPs and indicate that extracellular agents may program changes in cellular iron metabolism by altering the phosphorylation state of these regulatory RNA-binding proteins.
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PMID:Phosphorylation and activation of both iron regulatory proteins 1 and 2 in HL-60 cells. 863 54

There is increased incidence of infectious complications in uremic patients, indicating impairment of cellular host defense in these patients. Several reports confirm metabolic and functional abnormalities of polymorphonuclear leukocytes (PMNL) including altered adherence to endothelial cells, altered generation of reactive oxygen species, altered release of microbial enzymes, impaired chemotaxis, phagocytosis, intracellular killing of bacteria, altered carbohydrate metabolism, and/or impaired ATP formation. Several studies report on correlations between PMNL dysfunction, especially phagocytosis and oxidative burst, and ferritin content. Deferoxamine therapy improved PMNL function. Chronic renal failure is a state of increased cytosolic calcium. Increased cytosolic calcium is associated with several alterations of PMNL function and metabolism, which improve by normalization of cytosolic calcium either by calcium channel blockers or by lowering of elevated parathyroid hormone. Each hemodialysis session using bioincompatible membranes triggers neutrophil activation, evidenced by overexpression of adhesion molecules, elevation of cytosolic calcium, release of PMNL granular enzymes, and generation of reactive oxygen species. Several studies claim that this results in chronic downregulation of phagocyte function. Several granulocyte inhibitory compounds have been isolated and characterized from uremic serum. The uremic retention product p-cresol depresses respiratory burst activity. The following granulocyte inhibitory peptides could be isolated from dialysis patients: granulocyte inhibitory protein I and II with homology to light chain proteins and beta 2-microglobulin, degranulation inhibitory protein I and II being identical to angiogenin and complement factor D, and immunoglobulin light chains. These proteins inhibit PMNL function in nanomolar concentrations.
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PMID:Dysfunction of polymorphonuclear leukocytes in uremia. 873 62

The objective of this study was to determine the prevalence and possible pathogenesis of scoliosis in beta-thalassemia in our country, and to compare its characteristics to those of patients with idiopathic scoliosis from the same geographic area. Twenty-four [13 male and 11 female thalassemic patients aged 16 +/- 7 years (range 7-32 years)] of 115 examined patients with beta-thalassemia showed scoliosis of 14 degrees +/- 11 (range 10-65 degrees) radiologically. The prevalence of scoliosis in the thalassemic population was 21% in this series, whereas the overall prevalence of scoliosis in the general Greek population was 6% (Smyrnis PN, Valavanis J, Alexopoulos A, Siderakis G, Giannestras NJ: School screening for scoliosis in Athens, J Bone Joint Surg 61B:215-217, 1979). The scoliosis prevalence in the general population was significantly higher in the females (5%) than in the males (1%), whereas no difference in prevalence was found between the two sexes in the thalassemic population. The most common curve pattern in thalassemia was the left lumbar (38%) followed by the right lumbar (21%), whereas in patients with idiopathic scoliosis the left thoracolumbar most commonly appeared (25%) followed by the left lumbar (14%). No patient with thalassemia showed radiographic signs of congenital spinal deformities and spinal fractures, whereas all patients showed a significant retardation of their skeletal maturation. The age of the thalassemic patients with scoliosis was significantly (p = 0.0003) higher than in patients without scoliosis. The hematocrit of the thalassemic patients with scoliosis was significantly (p = 0.0012) lower than in those without scoliosis, whereas the rate of transfusions was not correlated with the magnitude of the scoliosis. The level of ferritin was significantly (p = 0.025) higher in the thalassemic patients with scoliosis than in those without scoliosis. The duration of Desferal treatment was significantly (p = 0.0357) longer in thalassemic patients with scoliosis when compared with those without scoliosis. Thus, the prevalence, curve pattern, and etiology of scoliosis in beta-thalassemia differ from those of idiopathic scoliosis, indicating that the spinal deformities in thalassemia represent a distinct type of scoliosis.
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PMID:Prevalence of scoliosis in beta-thalassemia. 879 87

Merocyanine 540 (MC540)-mediated photodynamic action is a novel approach for purging tumor cells from autologous remission bone marrow explants. The purpose of this study was to evaluate the effects of hemin (ferriprotoporphyrin IX), a potential source of pro-oxidant iron in bone marrow, on in vitro photodynamic inactivation of leukemia cells. Murine L1210 cells exhibited a progressive loss of clonogenicity when irradiated with broad-band visible light in the presence of MC540. Hemin had strikingly different effects on photokilling, depending on its contact time with cells, eliciting a sizable decrease in resistance after short-term (30-min) contact but a marked increase in resistance after long-term (24-h) contact. Similar trends were observed when cells were challenged with glucose/glucose oxidase, indicating that the responses apply to more than one type of oxidative stress. Immunoblot analyses revealed that the levels of inducible heme oxygenase (HO-1) and ferritin heavy (H) chain were substantially elevated 24 h after hemin addition. HO-1 increased relatively rapidly and maximized within 4 h after adding hemin, whereas H-ferritin increased more slowly in parallel with the development of hyperresistance, maximizing after 24-36 h. Desferrioxamine, an avid iron chelator, had no effect on HO-1 induction but inhibited both ferritin induction and the increase in cell resistance, suggesting that HO-mediated release of iron from hemin was necessary for triggering these responses. Spleen apoferritin was taken up by L1210 cells and strongly inhibited photokilling, further implicating ferritin involvement in hyperresistance. Photokilling was accompanied by free radical-mediated lipid peroxidation (thiobarbituric acid reactivity), which could be suppressed substantially by 24-h hemin preincubation. A plausible explanation for the long-term effects of hemin is that excess H-ferritin generated as a result of iron-regulatory protein deactivation sequesters toxic iron, which might otherwise catalyze damaging lipid peroxidation. Chronic oxidative release of hemin from bone marrow erythroid cells could compromise the efficacy of photopurging by making tumor cells more tolerant to photooxidative insult.
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PMID:Hyperresistance of leukemia cells to photodynamic inactivation after long-term exposure to hemin. 884 Sep 77

Mouse erythroleukemia (MEL) cells transformed by Friend virus and induced to undergo erythroid differentiation by treatment with hexamethylenebisacetamide (HMBA) increase erythroid specific 5-aminolevulinate synthase (ALAS-E) mRNA levels by 4-15-fold and decrease "housekeeping" 5-aminolevulinate synthase (ALAS-N) mRNA levels by 1.2-1.4-fold. Iron affects translation of (ALAS-E) mRNA but nothing is known about its effect at the pretranslational level of the expression of (ALAS-E) mRNA. The aim of this study was to examine the effect of iron on the synthesis of (ALAS-E) mRNA and (ALAS-N) mRNA. This effect was compared with the effect of iron on the iron on the synthesis of H-ferritin and transferrin receptor mRNAs. Incubation of uninduced or induced MEL cells with iron chelator pyridoxal isonicotinoyl hydrazone (PIH) or desferrioxamine (Desferal) and 3H-uridine decreased the level of the 3H-labeled (ALAS-E) mRNA. The treatment with either diferric transferrin or Fe-PIH increased the level of the 3H-labeled (ALAS-E) mRNA. The opposite effect was observed on the level of the 3H-labeled (ALAS-N) mRNA. These findings indicate that iron might play its role also at the pretranslational level of the expression of ALAS-E or in the stability of (ALAS-E) mRNA.
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PMID:The role of iron supply in the regulation of 5-aminolevulinate synthase mRNA levels in murine erythroleukemia cells. 884 57

A male patient with severe aplastic anemia was admitted for bone marrow transplantation. While waiting for a donor, high doses of methylprednisolone, anabolic steroid and granulocyte colony stimulating factor were given without response. Deferoxamine was administered for prophylaxis of hemochromatosis because of high level of ferritin. Acute right lower abdominal pain and pyrexia developed. A diagnosis of acute appendicitis was made and appendectomy was performed. The histopathological examination of the resected appendix revealed necrotizing hemorrhagic appendicitis with numerous hyphae of Mucorales. Though anti-fungal agent (amphotericin B) administration was continued, he subsequently developed ileo-cecal abscess and eventually died due to myoglobinuric nephropathy caused by extensive necrosis of the iliopsoas muscle. Autopsy revealed dissemination of hyphae of Mucorales in lungs, kidneys, large vessels and muscle of the bilateral lower limbs. Systemic vascular invasion and embolization of fungal hyphae were also observed. However, culture of exudate sampled from ileocecum yielded no Mucorales. It was emphasized that antemortem diagnosis and effective anti-fungal treatments are essential for the management of intestinal mucormycosis. The relation ship between mucormyocosis and deferoxamine was also discussed.
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PMID:[Acute appendicitis caused by mucorales in a patient with severe aplastic anemia: report of an autopsy case]. 885 34

Ferritin is the main intracellular iron storage protein. Ferritin iron may be released by many reducing agents including ascorbate. In this work we report ferritin to catalyze the oxidation of ascorbate. The kinetics of this process were studied in detail in phosphate buffer (pH 7.40), at 37 degrees C by using the Clark electrode technique and ESR. The catalytic effect of ferritin manifested itself as the increase both in the rate of oxygen uptake and steady-state concentration of the ascorbate radical. The ferritin catalytic activity was found to be modified by iron chelators, EDTA. Desferal (DFO) as well as by ferrozine (FRZ) which is widely used in kinetic studies on ferritin iron release thanks to the formation of a coloured complex with Fe(II). While EDTA promotes the catalytic action of ferritin, DFO and FRZ diminished it. From the comparison of the kinetics of ascorbate oxidation obtained in the current work and data on the kinetics of ferritin iron release reported by Boyer and McCleary ((1987) Free Rad. Biol. Med. 3, 389-395), we conclude that iron bound to ferritin rather than the iron released is likely responsible for ferritin catalytic action. In addition, it has been concluded that the use of FRZ as an analytical reagent in kinetic studies of reductive ferritin iron release requires taking into account the competitive character of the formation of the Fe(II)-FRZ complex.
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PMID:Iron bound to ferritin catalyzes ascorbate oxidation: effects of chelating agents. 913 40

Desferrioxamine (DFX) remains the most effective and safe iron chelator for treatment of patients with transfusional iron overload. It is usually given by intermittent subcutaneous infusions for 8-12 h on 4-6 days weekly using a battery-driven pump. Disposable balloon infusers provide a suitable method of giving continuous subcutaneous infusions with improved patient compliance. For patients with cardiac abnormalities due to iron overload, continuous intravenous desferrioxamine is essential to eliminate toxic plasma non-transferrin bound iron and to reduce body iron stores. Deferiprone (L1, l-2 dimethyl-3hydroxy-pyrid-4-one) is a less effective iron chelator but has the advantage of being orally active. Long-term trials in which patients have taken 75 mg/kg/day have shown that deferiprone is capable of maintaining body iron stores at safe levels in a proportion of thalassaemia major patients but body iron stores, assessed by liver biopsy remain at high levels (> 15.0 mg/g dry weight) in a substantial number of patients. These concentrations have been associated with tissue damage. Trials of increased doses of deferiprone (up to 100 mg/kg/day) or of combined therapy with daily deferiprone and DFX or 1 or 2 days each week are being carried out in an attempt to achieve lower body iron burden in these patients. Preliminary results show that the drugs can be given safely together and urine iron excretion produced is additive, implying that the drugs chelate different body iron pools. Patients previously well chelated with serum ferritin levels less than 2500 micrograms/L have the fewest side-effects from deferiprone and usually may be kept at the same level of body iron for periods of at least 4 years, assessed by serum ferritin and urine iron excretion. The side-effects of deferiprone result in some patients discontinuing therapy. These side-effects, especially arthropathy, mainly occur in previously poorly chelated and so the most heavily iron-loaded patients. Nausea and other gastrointestinal symptoms, agranulocytosis or milder degrees of neutropenia account with arthropathy for nearly all the withdrawals from deferiprone therapy. Patients with cardiomyopathy due to iron overload should be given intravenous DFX rather than deferiprone. Deferiprone, licensed for pharmaceutical use in India, awaits official approval for widespread clinical use in Western Europe and North America. Meanwhile, attempts to find new orally active iron chelators and improved methods of administration of desferrioxamine are in progress.
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PMID:Iron chelation therapy. 935 Jan 80


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