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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Members of the endogenous flora have become recognized as major pathogens in nosocomial infections, and the intestinal tract has become recognized as a major portal of entry for these pathogens. The English-language literature on this topic has been summarized and a working hypothesis devised describing a mechanism whereby intestinal bacteria can escape and cause systemic disease. It is postulated that the motile phagocyte ingests intestinal bacteria, transports them to extraintestinal sites, fails to accomplish intracellular killing, and then liberates the bacteria in the extraintestinal site. This hypothesis is consistent with many observations found in the literature: (1) The intestinal bacteria that most readily translocate out of the intestinal tract are classified as facultative intracellular pathogens. (2) Intestinal particles with no intrinsic motility (e.g., yeast, ferritin, starch) can translocate out of the intestinal lumen within hours after their ingestion. (3) The rate of translocation of intestinal bacteria can be altered with agents that modulate immune (including phagocytic) function. In the context of the mechanisms involved in intestinal immune responses, bacterial translocation appears to be a part of the normal antigen-sampling process of gut-associated lymphoid tissue. Systemic disease caused by translocating intestinal bacteria could be due to a maladaptation of the antigen-sampling process that has been designed to regulate the immune response to intestinal antigens.
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PMID:Proposed mechanisms for the translocation of intestinal bacteria. 305 94

Horse-spleen ferritin was found to bind Al systematically following gel filtration in buffered Al citrate 30 microM, and up to molar ratio 98 when incubated at 37 degrees C with Al citrate, buffered to pH 7.4. Pre-incubation with 3 concentrations of neutral sodium phosphate (0.1, 1.0, 10.0 mM) had no significant effect on binding. Apotransferrin interaction with the Al-ferritin complex to release Fe but not Al. Protein-digestion and EDTA washing procedures showed that the Al was firmly bound to the ferritin, probably to the core. Since ferritin species from different organs are relatively alike, we suggest that in the gut ferritin may scavenge Al followed by its re-excretion into the lumen with the mucosal cells, thus protecting against absorption of the metal.
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PMID:Interaction of horse-spleen ferritin with aluminium citrate. 314 25

Manduca sexta larvae accumulate large amounts of iron during their larval feeding period. When 59Fe was fed to 5th instar larvae, it was evenly distributed among the hemolymph, gut and carcass until the cessation of feeding. By pupation 95% of the labelled iron was found in the fat body. In the adult a significant portion of this iron was found in flight muscle. Studies of the hemolymph disclosed two iron-containing proteins. The first was composed of a single polypeptide chain of 80 kD, containing one atom of iron. This protein bound ionic iron in vitro and was able to transfer this iron to ferritin when incubated with fat body in vitro. Therefore, it appeared to serve a transport function. The second protein had a molecular weight of 490 kD with subunits of 24 and 26 kD and contained 220 micrograms of iron/mg protein. Its chemical and ultrastructural characteristics were those of ferritin. These studies demonstrate the presence of both a transport protein and a unique circulating ferritin in Manduca sexta, the latter serving a storage function during development and possibly also a transport function.
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PMID:Iron binding proteins and their roles in the tobacco hornworm, Manduca sexta (L.). 319 82

IgA and IgM antibodies were detected in rat milk after immunization with ferritin in Peyer's patches (Pp) 1 day after parturition but not after intramammary gland or intravenous immunization. The antibody levels decreased from day 9 to day 17 of the nursing period and were undetectable during a second lactation period. Despite the absence of milk IgM antibodies after intramammary gland or intravenous immunization, the serum levels of the IgM antibodies were similar after all three immunization methods. IgA antibodies were not found in serum after any of the immunization methods.IgG antibodies appeared in serum and milk after P. intramammary gland, and intravenous immunization. Milk and serum IgG antibodies from all the Pp-immunized animals decreased from day 9 to day 17 of the lactation period. After intramammary gland immunization, however, the IgG antibody levels increased in all the milk samples, but only in four of seven sera. The milk and serum IgG antibody levels were lower but still detectable during a second lactation period. Re-injection of ferritin in the Pp during a third lactation period resulted in higher levels of milk IgA, IgG and IgM antibodies than after the first injection. Rats with serum IgG antibodies against Escherichia coli 08 naturally present in their gut flora had no corresponding milk antibodies of any isotype. The results suggest tht milk antibodies of all three isotypes stem from local production in the mammary gland and that blood IgG and IgM antibodies originate at least partly from stimulation in Pp.
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PMID:Origin and kinetics of IgA, IgG and IgM milk antibodies in primary and secondary responses of rats. 351 99

Most IgA plasma cells in the digestive tract are thought to derive from gut-associated lymphoid tissue, whereas IgA plasma cells in the respiratory mucosa are thought to originate largely in bronchus-associated lymphoid tissue. However, previous work has also shown that IgA antibodies to gut antigens can be detected in immunocytes of the bronchial mucosa and in bronchial secretions after appropriate stimulation via the gut. To analyze the cellular origin of such respiratory antibodies, mice were orally immunized with ferritin for 40 days and then segregated for intrabronchial challenge as follows: one group was given saline, another group Formalin-fixed Escherichia coli as a nonspecific challenge, and a third group ferritin. Lungs and intestines from these animals were then examined by immunofluorescence for the presence of plasma cells containing particular isotypes of antibody to ferritin. Animals fed ferritin and given saline or E. coli intrabronchially showed a greater than 6-fold increment in IgA antiferritin plasma cells in the bronchial mucosa, compared to animals which had not received ferritin, whereas orally immunized animals challenged intrabronchially with ferritin showed a greater than 15-fold increase. In other experiments, ferritin-naive animals transfused with mesenteric node cells that were obtained from donors that had been orally immunized with ferritin and were already committed to IgA production showed a 4-fold or greater increase in IgA antiferritin plasma cells in respiratory mucosa after intrabronchial challenge with ferritin when compared to recipients of peripheral node cells from the same donors or to recipients of mesenteric node cells that had not been specifically boosted intrabronchially. These results suggest that immunologically specific IgA immunocytes from gut-associated lymphoid tissue can migrate to the respiratory mucosa after oral immunization, and that migration and/or local cell division are enhanced by subsequent intrabronchial challenge. In providing further evidence for interrelations between gut-associated and bronchus-associated lymphoid tissue, the findings lend added support to the overall concept of a generalized secretory immune system.
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PMID:Gut-associated lymphoid tissue as source of an IgA immune response in respiratory tissues after oral immunization and intrabronchial challenge. 356 43

Test solutions of cadmium and labeled iron salts, soluble complexes of diferric transferrin, or hemoglobin iron were introduced orally or were injected into tied-off jejunal segments in rat. Cadmium reduced the absorption of iron salts to about half in both normal and iron-deficient rats. Hemoglobin iron absorption was enhanced, indicating that the processing of this form or iron and its release from mucosa to blood was intact. A greater reduction in iron absorption occurred in iron-deficient rats when transferrin iron was injected into gut loops. Mucosal radioiron content in animals given cadmium with either iron salts or transferrin iron was increased. The primary effect of cadmium was on intracellular processing of iron salts and transferrin iron. The major portion of cadmium taken up by the mucosa of normal animals was bound to ferritin, and the effect of cadmium within the mucosal cell may be reduced thus.
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PMID:The cadmium effect on iron absorption. 357 91

Macrophage ferritin content was determined following culture of peripheral blood monocytes for a period of 8 d in 40% autologous plasma to render them mature macrophages. Ferritin content was measured prior to and following culture using the radioimmunoassay. The normal range of values was established in a group of 22 healthy volunteer blood donors. A significant increase in the ratio of macrophage/monocyte ferritin was observed in every donor studied (range 1.2 - 1.8, p less than 0.001). Also, a further significant increase was observed when these macrophages were additionally incubated for 6 h with heterologous antibody-coated sheep red blood cells (range 1.2 - 1.57, p less than 0.001). Finally, the same studies were performed on a group of thalassemic patients with and without intrinsic iron overload. Again there were significant increases in monocyte ferritin content following culture as well as ingestion of heterologous sheep red cells, with magnitudes similar to those obtained with normal donor monocytes. Therefore we could not demonstrate the presence of a cellular ferritin synthesis defect in macrophages of thalassemic patients with intrinsic iron overload to explain the uncontrolled absorption of dietary iron from their gut.
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PMID:Ferritin synthesis by monocyte-derived macrophages in thalassemic patients with intrinsic iron overload. 359 6

To evaluate the incidence of either evident anemia or a subclinical status of iron deficiency in celiac disease (CD), we studied 80 celiac children aged 6 months to 18 years. They were subdivided into various groups according to morphology of gut mucosa and diet. Only eight of 47 celiac children had an evident anemia at the time of the first peroral bowel biopsy. In addition, 51% of the patients with atrophic mucosa and 56% of the children on a gluten-containing diet had serum iron levels less than 50 micrograms/dl; 35% of patients of both groups had serum ferritin levels less than 12 micrograms/L. On the contrary, only a small number of children with normal mucosa on a gluten-free diet showed a laboratory, subclinical picture of iron deficiency. The results of our study can therefore be summarized in three major items: (a) Low levels of both serum iron and ferritin can frequently be found during active CD. (b) Regular determination of serum iron levels appears to be useful in controlling the state of iron stores in such patients, as well as in deciding whether and when to recommend temporary iron supplementation. (c) Serum ferritin tests did not offer more information than the easier and cheaper serum iron determinations.
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PMID:Iron deficiency in children with celiac disease. 369 63

Radioiron was introduced into the intestinal lumen to evaluate absorption, injected as nonviable red cells to evaluate reticuloendothelial (RE) processing of iron, and injected as hemoglobin to evaluate hepatocyte iron processing. Redistribution of iron through the plasma was evaluated in control animals and animals whose transferrin was saturated by iron infusion. Radioiron introduced into the lumen of the gut as ferrous sulfate and as transferrin-bound iron was absorbed about half as well in iron-infused animals, and absorbed iron was localized in the liver. The similar absorption of transferrin-bound iron suggested that absorption of ferrous iron occurred via the mucosal cell and did not enter by diffusion. The decrease in absorption was associated with an increase in mucosal iron and ferritin content produced by the iron infusion. An inverse relationship (r = -0.895) was shown between mucosal ferritin iron and absorption. When iron was injected as nonviable red cells, it was deposited predominantly in reticuloendothelial cells of the spleen. Return of this radioiron to the plasma was only 6% of that in control animals. While there was some movement of iron from spleen to liver, this could be accounted for by intravascular hemolysis. Injected hemoglobin tagged with radioiron was for the most part taken up and held by the liver. Some 13% initially localized in the marrow in iron-infused animals was shown to be storage iron unavailable for hemoglobin synthesis. These studies demonstrate the hepatic trapping of absorbed iron and the inability of either RE cell or hepatocyte to release iron in the transferrin-saturated animal.
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PMID:The effect of transferrin saturation on internal iron exchange. 374 34

To determine whether the midgut envelope of mosquitoes is disrupted by the passage of microfilariae, ultrastructural changes induced by microfilariae of Brugia malayi were observed in midguts of Aedes aegypti mosquitoes. Basal and apical plasma membranes were destroyed, disrupting the full depth of the midgut wall. Ingested ferritin lay against the gut wall, suggesting absence of the peritrophic membrane during penetration. Exsheathment of microfilariae appears to be enhanced by movement against the constricting midgut wall. It was concluded that particles present in the lumen of the gut may be disseminated passively to the hemocoel.
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PMID:Microfilarial perforation of the midgut of a mosquito. 380 21


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