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)

Antigens on the epicuticular surface of Strongyloides ratti infective third-stage larvae (L3) were demonstrated by both ferritin-conjugated antibody and indirect fluorescent antibody techniques. The rat antibodies from immune serum that bind to these antigens were chiefly of the IgG2a subclass. Solubilization of these antigens by extraction with detergents, hypertonic salt, organic solvents and by freezing and thawing was limited as measured by the reduction in antibody binding to the epicuticle. The epicuticular antigens were resistant in situ to degradation by a variety of proteases, carbohydrases and lipase. Infectivity of the L3 in the rat was not reduced by prior sensitization with rat antibody. The epicuticular antigens are not completely species-specific since antibody from S. ransomi-infected pigs cross-reacted well with S. ratti L3 antibody. However, high levels of resistance to S. ratti could be induced in rats only by multiple inoculations of heat-killed S. ratti L3.
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PMID:Solubilization studies on the epicuticular antigens of Strongyloides ratti. 675 14

Glomus cells from carotid bodies of adult rats dissociated by means of collagenase or collagenase + trypsin were used to study by electron microscopy the endocytotic uptake of cationized ferritin (CF) tracer into subcellular compartments. The glomus cells were incubated with the tracer (1) in a basic salt medium (BM), or (2) in the BM into which calcium ionophore A23187 had been added, or (3) in a potassium-rich medium. Incubation of the cells in BM containing CF for 30 min resulted in attachment of the tracer to the cell membrane and uptake of a few solitary tracer particles into small vesicles and multivesicular bodies. No uptake into the cisternae of the Golgi apparatus was observed. Further incubation in BM containing CF for another 30 min resulted in increased uptake of the tracer into small vesicles and multivesicular bodies. A similar pattern of uptake was observed when the dissociated glomus cells were first preincubated in BM with CF for 30 min and then incubated for 1 min or 30 min in the BM solution containing both the ionophore and CF. Upon such incubation, CF particles were seen to penetrate into coated pits and sites of exocytosis at the cell surface. When the 30-min preincubation in BM was followed by incubation in a CF-containing potassium-rich medium for 15-30 min, uptake into vesicles, small lysosomes and occasionally also into profiles of the smooth endoplasmic reticulum was seen. Endocytotic mechanisms of the glomus cells are outlined.
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PMID:Endocytotic uptake of cationized ferritin tracer into glomus cells dissociated from the adult rat carotid body. 681 57

The ferritin from the spleen of the chickens has been isolated by a method of salt fractionation and by a pH change followed by purification in sephadex G-200. 2. The identification of the protein was carried out by acrylamide gel electrophoresis showing a single band. 3. The characterization of ferritin has been made by determination of molecular weight, amino acids analysis and the number of iron atoms (4520) which bound the ferritin. 4. The ferritin from the spleen of chicken is compared with the ferritin from the liver of pigeon.
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PMID:Isolation, purification and characterization of spleen ferritin of Gallus domesticus L. 683 25

We have identified the ultrastructural localization of anionic sites on the luminal surface of the pulmonary microvascular endothelium by perfusing isolated rat lungs with polycationized ferritin (CF). The ligand decorated preferentially the luminal plasmalemma, coated pits, intercellular clefts, and about half of the plasmalemmal vesicles open to the lumen. Decoration of the plasmalemma was not uniform particularly in the nonvesiculated regions of the endothelium. Perfusion of the lung with high salt solution completely abolished binding of CF to the plasmalemma, coated pits, and intercellular clefts but did not significantly decrease binding of CF to the diaphragm of the luminal plasmalemmal vesicles. This indicates the presence of highly charged anionic sites on these regions of the endothelium. CF was taken up by vesicles and discharged on the capillary membrane. Perfusion of the lungs at 4 degrees C completely abolished transport of CF across the endothelium but did not modify the pattern of binding to the luminal endothelial surface. These findings are regarded as evidence for a functional subspecialization of plasmalemmal vesicles in the pulmonary microvascular endothelium.
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PMID:Transcapillary movement of cationized ferritin in the isolated perfused rat lung. 686 31

Monolayer cultures of Ehrlich ascites tumor cells in exponential growth phase were treated with X-rays and neuraminidase alone or in combination. A radiation dose of 2 Gy (200 rd) and higher effected a significant inhibition of DNA synthesis and cell proliferation. Neuraminidase treatment in addition to irradiation did not modify the growth-inhibitory irradiation effect. Cells pretreated for 0.5 to 1.0 hours with neuraminidase (in Earle's salt solution) and cultured thereafter (4h) in serum-containing growth medium exhibited an enhanced development of the microtubule-microfilament-system. Morphometric analysis of microtubules on electronmicroscopic sections revealed a nearly 4-fold increased number in neuraminidase treated cells while the average length of microtubules was similar to controls. Pinocytosis as measured by the ultrastructural uptake of ferritin appeared to be increased following neuraminidase treatment. A connection between neuraminic acid containing components (glycoproteins or glycolipids?) of the cell membrane or cell surface, on the one hand, and the cytoskeleton and the endocytotic process of these tumor cells, on the other hand, is suggested.
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PMID:[Action of x-rays and neuraminidase on pinocytotic activity and microtubule-microfilament system of Ehrlich ascites tumor cells in monolayer culture (author's transl)]. 719 7

Earlier investigators observed that addition of large amounts of zinc to the diet or rats can retard growth, lower their hemoglobin levels and reduce storage of iron. In the present studies, addition of 0.75% zinc to a synthetic diet confirmed the reduced storage of iron in the livers and spleens of growing rats, but failed to show an effect on growth rate or hemoglobin levels. The adverse effects of zinc excess on growth and hemoglobin level could, however be reproduced by replacing the Rogers-Harper salt mixture used in the present studies with the Wesson salt mixture use in the earlier studies. Rats fed excess zinc along with the Wesson salt mixture grew less well, had anemia and also had low level in copper in their livers. It is suggested that addition of zinc to the low copper Wesson salt mixture reduced copper absorption sufficiently it deplete liver copper to a level at which mobilization of liver iron stores by a copper-dependent mechanism became impaired, thus depriving red cell production and tissue enzymes of stored iron. The mechanism by which iron stores are depleted by addition of zinc to the better balanced Rogers-Harper salt mixture remains unexplained It is not due to interference by zinc with iron adsorption from the diet nor with cellular uptake of iron from circulating transferrin, and the capacity of tissues to store iron as ferritin is not impaired.
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PMID:Effect of excess dietary zinc on tissue storage of iron in rats. 729 94

Exopolysaccharide (EPS) synthesis by Erwinia amylovora depends on environmental and genetic predispositions. To measure the amount of the acidic EPS amylovoran synthesized by E. amylovora cell cultures, a turbidity assay using cetylpyridinium salt was developed. The EPS produced by bacteria grown on solid media was additionally characterized by its water content. The amylovoran capsules were visualized in situ by staining with fluorescein isothiocyanate (FITC)-labelled lectin from Abrus precatorius, which reacts with the galactose residue of the EPS side chain. The staining and the turbidity assays were applied to suspension cell cultures or to cells from colonies and did not require any purification steps. Lectin staining was superior to electron microscopic (EM) techniques for visualization of capsules. For EM, the capsule was stabilized with polycationic ferritin. In contrast to lectin staining, only a small fraction of the cells was found to be EPS-coated in the EM assay. An increase in capsulation and in amylovoran production was found in conjunction with mutations in a ribosomal protein conferring resistance to streptomycin. Furthermore, the presence of sorbitol in the growth environment resulted in high synthesis of amylovoran. Cells in the stationary growth phase continued to produce amylovoran. Apparently, the strong dependence of the fireblight pathogen on capsules requires the capacity for EPS synthesis in all growth stages in order to escape plant defence reactions.
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PMID:Visualization of capsule formation by Erwinia amylovora and assays to determine amylovoran synthesis. 753 77

The prevelance of IDA in industrialized countries has declined in recent decades, but there has been little change in the worldwide prevalence. IDA is currently estimated to affect more than 500 million people. Recent studies have indicated that anemia per se, the most common manifestation of iron deficiency, is less important from a public health standpoint than liabilities associated with tissue iron deficiency. The most important of the latter are an impairment in psychomotor development and cognitive function in infants and preschoolers, a deficit in work performance in adults, and an increase in the frequency of low birth weight, prematurity, and perinatal mortality in pregnancy. There have been several recent advances in combatting nutritional iron deficiency. One of the major problems has been in distinguishing iron deficiency from other causes of anemia seen epidemiologically such as malaria, HIV infection, chronic inflammation, hemoglobinopathies, and protein energy malnutrition. When combined with serum ferritin and hemoglobin determinations, the serum transferrin receptor assay is a valuable addition in epidemiologic surveys because it provides a quantitative measure of functional iron deficiency and it distinguishes true IDA from the anemia of chronic disease. The most difficult challenge is to develop effective methods of supplying iron to large segments of a population. Supplementation with iron tablets is suitable for only brief periods of need such as during pregnancy. The poor compliance with existing supplementation programs is believed to be due mainly to the gastrointestinal side effects of oral iron which can be eliminated by the use of a gastric delivery system. The most effective long-term strategy is to increase the intake of bioavailable iron in the diet. The customary approach has been to fortify a food staple such as wheat, rice, sugar, or salt, and thereby increase the iron intake of the entire population. However, because of concerns about the risk of cancer and heart disease in individuals with high iron stores, there is an increasing reluctance to supply iron to individuals who do not require it. A more effective strategy is to fortify food vehicles that are targeted to segments of the population at greatest risk of iron deficiency such as infants and school children. Because of the strong inhibitory properties of diets in regions of the world where iron deficiency is most prevalent, the use of NaFeEDTA has important advantages for food fortification.
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PMID:Iron deficiency: the global perspective. 788 26

A previous report from this laboratory described an estrogen-regulated endoribonuclease activity on Xenopus liver polysomes which had properties one might expect for a messenger ribonuclease involved in the regulated destabilization of albumin mRNA (Pastori, R. L., Moskaitis, J. E., and Schoenberg, D. R. (1991) Biochemistry 30, 10490-10498). This report describes the purification and properties of this ribonuclease. The purified nuclease fraction contained a doublet of 62 and 64 kDa and a small amount of a 40-kDa peptide. In situ analysis on both denaturing and nondenaturing gels using an albumin transcript as substrate showed all three proteins possess nuclease activity. Peptide mapping and Western blot with a polyclonal antiserum showed the 62- and 64-kDa peptides to be isoforms, and the 40-kDa peptide to be a degradation product of the larger species. Two-dimensional gel electrophoresis further separated the 62- and 64-kDa species into three pairs of proteins, with isoelectric points of 9.6, 9.8, and 9.8. The purified ribonuclease rapidly degraded a full-length albumin transcript, yet had no effect on either a full-length albumin antisense transcript or full-length ferritin transcript. A number of properties of the purified nuclease were characterized, including the effects of salt, divalent cations, EDTA, sulfhydryl reagents, and temperature. Treatment of the polysomal nuclease with micrococcal nuclease had no effect, indicating that this enzyme does not require an RNA cofactor for activity. Finally, primer extension mapped the major cleavage site to an overlapping repeated sequence APyrUGA, with cleavage between and adjacent to the two pyrimidine residues generating fragments with 5'-hydroxyls.
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PMID:Purification and characterization of an estrogen-regulated Xenopus liver polysomal nuclease involved in the selective destabilization of albumin mRNA. 789 Jul 44

Ferritins are 24-mer proteins which store and detoxify intracellular iron. Mammalian ferritins are made of two subunit types, the H- and L-chains, with different functional specificity. The H-chain has a metal-binding site (the ferroxidase center) which confers ferroxidase activity to the protein and accelerates iron incorporation. In the L-chain the center is substituted by a salt bridge. We performed several site-directed mutageneses in the L-chain with the aim to construct the center and confer ferroxidase activity to the protein. Most variants were insoluble and did not refold into homopolymers, probably due to electrostatic repulsion introduced by the substitutions. However, they formed hybrids when they were renatured together with the L- or H-chains. The heteropolymers made of 90% L-chain and 10% of an L-variant with all the ligand residues of the H-chain center had 25-30% of the ferroxidase activity of the H-chain homopolymer. This corresponds to the activity of an H/L heteropolymer with 7% H-chain. It is concluded that: (i) it is possible to construct a ferroxidase center in the L-chain with an activity equivalent to that of the H-chain, (ii) the residues of the center interfere with the folding/assembly of the L-, but not of the H-chain, (iii) heteropolymers can be made even between ferritin subunits with large differences of refolding rates.
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PMID:Construction of a ferroxidase center in human ferritin L-chain. 798 45


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