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)

The comparative bioavailability from matching quantities of iron in the form of ferrous ascorbate or ferric polymaltose was defined in rats. Studies were carried out in the intact animals under basal conditions and also when requirements for this metal were either increased or decreased by manipulating stores or erythropoietic activity. No significant difference was found in the total quantity of iron absorbed from either salt or complex under any of these circumstances, suggesting that the mucosal mechanism regulating the overall process was common to both. However, the rate of transfer from the lumen into portal blood was distinctive, reaching a maximum with salt at 30 min compared to 24 h for the complex. To explore the possibility that iron from the two sources was initially handled by different subcellular pathways, the radiolabeled compounds were instilled into loops of bowel that had been isolated between ligatures in vivo. Enterocytes were harvested and fractionated, and incorporation into ferritin and transferrin was determined using RIA. From salt, iron appeared rapidly in duodenal but not ileal ferritin, whereas mucosal transferrin increased under conditions of stimulated absorption, suggesting that this protein may act as a shuttle for the metal. In contrast, iron from polymaltose showed a cumulative incorporation into duodenal ferritin over time that correlated with iron absorption, defined by the appearance of radiolabel in the serum and in the carcass; a similar pattern was demonstrable in ileal mucosal cells. Conversely, binding of iron to transferrin was minimal. No iron polymaltose was found within the mucosal cells. It is suggested that the low rate of iron transfer from this ferric complex may reflect its extracellular breakdown in the lumen of the gastrointestinal tract.
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PMID:Bioavailability and the mechanisms of intestinal absorption of iron from ferrous ascorbate and ferric polymaltose in experimental animals. 191 6

The location of the globular domain of histone H5 relative to the axis of the 30 nm chromatin fiber was investigated by following the accessibility of this region of the molecule in chicken erythrocyte chromatin to specific antibodies as a function of chromatin structure. Antibodies to the globular domain of H5 as well as their Fab fragments were found to react with chromatin at ionic strengths ranging from 1-80 mM NaCl, the reaction gradually decreasing upon increase of salt concentration. If, however, Fab fragments were conjugated to ferritin, no reaction of the complex with chromatin was observed at salt concentrations higher than 20 mM. The accessibility of the globular part of H5 in unfolded chromatin to the Fab-ferritin complex was also demonstrated with trypsin-digested chromatin. The experiments were carried out by both solid-phase immunoassay and inhibition experiments. The data obtained are consistent with a structure in which the globular domain of H5 is internally located in the 30 nm chromatin fiber.
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PMID:The globular domain of histone H5 is internally located in the 30 nm chromatin fiber: an immunochemical study. 244 34

A rapid three step procedure is described for the purification of C protein from HeLa 40 S hnRNP particles. The procedure takes advantage of the salt resistant RNA binding of C protein, the size of the C protein-RNA complex, and the strong binding of C protein to an anion-exchange resin. Typically 120 micrograms of C protein is obtained from 4.0 X 10(9) cells with greater than 95% electrophoretic purity. Proteins C1 and C2 copurify in the ratio of 3.5 Cl to 1 C2. The purified C protein participates in hnRNP particle reconstitution and on this basis is judged to be native. The purified C protein binds to a gel filtration matrix at 0.5 M NaCl but at higher salt concentrations it elutes before the marker protein, apoferritin (Mr = 443,000). An abbreviated two step purification procedure utilizing anion-exchange chromatography is also described. This procedure results in relatively pure C protein, as well as a useful separation of the other hnRNP proteins.
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PMID:Rapid purification of native C protein from nuclear ribonucleoprotein particles. 245 23

A method of affinity purification of a regulatory protein that binds specific RNA sequences is described. RNAs containing the regulatory sequences are transcribed in vitro from oligonucleotide templates, biotinylated, and incubated with unfractionated cytosol. Specific RNA-protein complexes are bound in solution to avidin, and the resulting complex is bound to biotin-agarose beads. The cytosolic binding protein is released from the RNA in high salt, and a second round of purification yields an essentially homogeneous protein. Using this method, we have identified the protein in human liver that binds iron-responsive RNA regulatory sequences. Iron-responsive elements (IREs) are RNA stem-loops present in the mRNAs encoding ferritin and the transferrin receptor. IREs form the basis for the translational regulation of ferritin gene expression and the regulation of transferrin receptor mRNA degradation rates. The IRE binding protein purified by this technique migrates as a 90-kDa polypeptide on SDS/PAGE. The interaction of the purified protein with IRE-containing RNAs can be detected by gel-mobility shift assays or by covalent crosslinking induced by UV irradiation.
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PMID:The iron-responsive element binding protein: a method for the affinity purification of a regulatory RNA-binding protein. 247 19

After exposure to ligand at 0-4 degrees C, estrogen receptors from mouse uteri characteristically eluted between thyroglobulin (Mr 669,000) and ferritin (Mr 443,000) during size-exclusion HPLC. However, when preparations were warmed with ligand under mild activating conditions, most or all of the receptor was observed as a much larger complex, which eluted between dextran blue 2000 and thyroglobulin. Formation of the large complex required ligand, was inhibited by molybdate, and occurred even in 0.4 M KCl. Slower ligand dissociation characterized the large complex, indicating that activated receptors were included preferentially. This large complex did not form when charged cytosols were aged, concentrated, or precipitated, indicating that formation was not the result of random aggregation. After exposure to conditions commonly used for activation (25 degrees C, 60 min), most receptor existed as a very large, monodisperse complex of finite size, predicting an ordered structure for these large complexes that should be useful for defining the types of proteins which can interact with estrogen receptors. Formation of the large complex was not impeded or disrupted by EDTA, RNase, DNase I, thiourea, or mercaptoethanol; however, the capacity to form this large complex was not demonstrated by preparations that had been exposed to trypsin or by the small receptor forms obtained after salt extraction. Proteolytic sensitivity and lack of sensitivity to RNase or DNase indicate that interactions between receptors and other proteins are involved in peak A formation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intermolecular engagement of estrogen receptors indicated by the formation of a high molecular weight complex during activation. 251 8

The absorption of radioiron in rabbit hemoglobin, hemin, and ferritin has been compared to that of ferrous salt in healthy volunteers and in subjects with iron-deficiency anemia. At a dosage level of 5 mg elemental iron, hemoglobin iron was as well or better absorbed than ferrous salts in the normal subject. Absorption of hemoglobin iron increased less, however, in the iron-depleted or iron-deficient subject. In contrast to the absorption of ferrous salts, that of hemoglobin iron was not decreased by food or by phytate nor increased by ascorbic acid. The absorption of hemin iron was also not decreased by food. Iron absorbed from hemoglobin appeared in the plasma later than that from ferrous salts, but was found to be similarly dialyzable at acid pH with EDTA. These findings suggest that iron in heme complexes is absorbed as a porphyrin complex without conversion to the free ionized form. It is further apparent that there is less effective mucosal regulation of absorption of iron in this form. Finally, the present hypothesis of iron absorption based on the behavior of iron salts is not adequate for all types of food iron.
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PMID:The Journal of clinical Investigation, Volume 41, 1962: iron absorption. IV. The absorption of hemoglobin iron. 265 69

The surface reactivity of the dog heartworm (D. immitis) was evaluated by comprehensive contact angle measurements and a platelet retention test. Contact angle data yielded calculated surface energy terms very similar to those previously reported for intact vascular endothelium. The platelet test revealed the native worm surface to be nonreactive, retaining fewer platelets than glass or worms whose surfaces had been modified by extraction with acid and high salt solutions. The cuticular morphology of the heartworm was studied with both light and electron microscopy, the latter coupled with ferritin-conjugated double-layer immunolabeling to reveal adsorbed host protein on the cuticle surfaces. Multiple attenuated internal reflection (MAIR) IR spectroscopy confirmed the general composition of this surface layer to be glycoproteinaceous. Morphological and histochemical studies confirmed and extended previous descriptions of nematode cuticle, adding ultrastructural detail on cortical, medial, and basal layers. A trilaminar membrane, apparently corresponding to a mammalian cell membrane (plasmalemma), constituted the external cortical layer as observed in high magnifications. The existence of a glycocalyx of varying thickness was demonstrated in ruthenium red-stained sections. MAIR IR spectra showed this glycoproteinaceous film to appear, in fully hydrated samples, as a loose biological gel. Ferritin-antibody conjugate labeling confirmed the presence of adsorbed dog albumin, dog immunoglobulin class G (IgG) and dog complement fraction 3 (C3) in the cuticular surface layer. It is likely, therefore, that D. immitis heartworms demonstrate long-term thromboresistance at least in part due to their passive low-surface-energy overcoating with host proteins.
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PMID:Surface characterization of the cuticle of Dirofilaria immitis. 277 32

Recent studies have suggested a role for thromboxane in the progression of renal disease. The current study evaluated the role of this arachidonic acid metabolite in a model of renal disease which bears many biologic similarities to that in the kidneys of patients with chronic progressive renal failure. The model is that induced by ferritin-anti-ferritin immune complex nephritis in Dahl-salt sensitive rats rendered hypertensive by a high salt intake. Rats with this model of renal disease were chronically given a thromboxane synthetase antagonist OKY-046 or a placebo treatment from 16 to 29 weeks of age. Sequential observations of serum creatinine and 24-hour urinary protein excretion showed an ameliorating effect of OKY-046 on these renal parameters. Histologic examination of the kidneys also showed significantly less glomerular sclerosis in OKY-046 treated animals. The efficacy of OKY-046 was monitored by measurements of serum TXB2 levels and of glomerular production of TXB2 (and other prostaglandins); amounts of TXB2 were significantly reduced in the OKY-046 group. It is concluded that blockade of thromboxane generation has been successful in ameliorating the functional and structural lesions in this model of renal disease, providing further support to the thesis that thromboxane is an important mediator in events leading to eventual chronic renal failure and sclerosis.
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PMID:A thromboxane synthetase antagonist ameliorates progressive renal disease of Dahl-S rats. 296 73

The relationship between hypertension, ferritin-antiferritin mesangial immune injury (FIC), and progressive glomerular damage was studied in hypertensive (8% NaCl chow) Dahl salt-sensitive rats (DS) and in spontaneously hypertensive rats (SHR). The glomeruli of SHR are protected from the increased perfusion pressure that accompanies systemic hypertension by preglomerular vasoconstriction, while the glomeruli of hypertensive DS are not. Blood pressure, serum creatinine levels, urinary protein excretion, and glomerular injury (assessed by semiquantitative morphometric analysis) were determined in 20-week-old SHR and DS with FIC. In addition, half of a group of 20-week-old SHR with FIC were uninephrectomized and progression of glomerular injury was assessed 12 weeks later. Control rats for each of the groups did not receive FIC. Our studies showed that more extensive mesangial expansion and glomerulosclerosis developed in hypertensive DS with FIC than in rats without FIC. Glomerular injury in DS with FIC affected cortical and deep glomeruli. Similarly, hypertensive SHR with FIC had minimal damage in cortical glomeruli. In deep glomeruli of SHR, mesangial expansion was similar to that of DS, but glomerulosclerosis was absent. In SHR, a 50% reduction in renal mass, a maneuver known to decrease preglomerular vasoconstriction, resulted in mesangial expansion similar to that in DS in cortical glomeruli while deep glomeruli developed mesangial expansion as well as glomerulosclerosis. Our results suggest that when hypertension and mesangial immune injury coexist with renal vasodilatation (as occurs in DS with 2 kidneys and in SHR after uninephrectomy), they act synergistically to induce progressive glomerular damage. Similar mechanisms may be operative in hypertensive humans with glomerulonephritis and may condition the rate of progression to renal insufficiency.
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PMID:Role of hypertension in progressive glomerular immune injury. 315 4

The major diseases of iron metabolism are iron deficiency anaemia, which could be treated using Fe2+ or Fe3+ salt supplements, and iron overload, which could arise either from an increased gastrointestinal absorption of iron or from recurrent blood transfusions. While the former form of iron overload could be treated by phlebotomy the latter requires the use of a chelator. Desferrioxamine is the only clinically available chelator for the treatment of iron overload but its use worldwide is limited because it is expensive and orally inactive. Several alpha-ketohydroxy heteroaromatic chelators have been synthesised and tested for their iron binding properties at physiological pH. The synthetic route involves the benzylation of the hydroxyl group of maltol using benzyl chloride, the conversion of the benzylated maltol to the 1-alkyl benzylated pyridine derivative by introducing the corresponding alkylamine in alkaline conditions and the cleavage of the benzyl group in acid to form the 1-alkyl-2-methyl-3-hydroxypyrid-4-one. All the chelators are water soluble and stable at a wide range of pH, forming stable, water soluble, coloured iron complexes with a molar ratio of approximately 3 chelator: 1 iron at pH 7.4 and lower molar ratio of chelators to iron complexes at acidic pH. When the 1-methyl, 1-ethyl and 1-propyl, -2-methyl-3-hydroxypyrid-4-ones were mixed at pH 7.4 with transferrin, ferritin and haemosiderin substantial amounts of iron were released.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:New synthetic approach and iron chelating studies of 1-alkyl-2-methyl-3-hydroxypyrid-4-ones. 343 80


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