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)

Mice were induced to produce IgA antibodies against ferritin after oral immunization. Such antibodies were detected by immunofluorescence in plasma cells in the intestinal mucosa as well as in secretory sites located elsewhere, such as the lactating mammary gland, salivary gland, and respiratory tract. The observation suggested that cells immunized locally via the gut could home to distant secretory sites. To confirm this hypothesis, lymphocyte transfer studies were done with mesenteric node (MN) versus peripheral node (PN) cells from orally immunized donors into nonimmunized recipients. IgA anti-ferritin cells from MN homed to exocrine targets, whereas IgM and IgG anti-ferritin cells homed to PN. The findings overall support the concept of a generalized and interrelated secretory immune system.
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PMID:Organ and isotype distribution of plasma cells producing specific antibody after oral immunization: evidence for a generalized secretory immune system. 47 96

The uptake in vitro of various substances by Brugia pahangi was investigated using infective larvae obtained from Aedes aegypti and worms removed from Meriones unguiculatus at 2, 3, 10, 20 and 90 days post-infection. Worms incubated in growth medium 199 containing 1% Trypan blue possessed demonstrable dye in the oral orifice, the anterior oesophageal lumen and the external openings of the vulva and the cloaca or anus but the dye was not found in the gut lumen even after incubation for 24 h. No uptake of ferritin particles into the intestine of the worms was found and no fluorescence could be demonstrated in the gut lumen of worms incubated in medium containing 50% (v/v) fluorescein isothiocyanate-conjugated calf serum for up to 24 h. Trypan blue uptake by the gut of Aspiculuris tetraptera was clearly observed after incubation for several hours. The uptake of D-glucose and L-leucine by B. pahangi was demonstrated using autoradiographic and scintillation counting techniques and incorporation into worm tissues was detected. Glucose was found to be readily incorporated in the apical, glycogen-rich areas of the myocytes of worms of all ages studied and in the uterine epithelium of the adult female. In contrast, a lower incorporation of D-glucose was found in the eggs, embryos and vas deferens and especially in the gut. The incorporation of L-leucine occurred throughout the tissue of the worms during a 30 min incubation. Labelling was also located over the surface of the cuticle of the worms, when incubated for a period of 15 to 60 min in L-[H]leucine. Scintillation counting techniques demonstrated that there was no uptake of 14C-labelled L-glucose or sucrose by B. pahangi. The data presented on the uptake in vitro of nutrients or other compounds by infective larvae and adult stages of B. pahangi did not demonstrate an intestinal route of uptake but indicated that the transcuticular route of uptake may be employed.
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PMID:The uptake in vitro of dyes, monosaccharides and amino acids by the filarial worm Brugia pahangi. 48 11

The ratios of plasma proteins and ferritin (introduced into the gut) were determined between the jejunal lacteals and the interstitial channels in puppies. This was done by fine structural densitometry and the counting of molecules, respectively. In the normal state this ratio was approximately 2. In portions of tissue whose smooth muscle had been relaxed by atropine the ratio was approximately 1; in others, where the muscle had been contracted by Carbacol, it was approximately 3. These latter correspond approximately to the filling-phase and the emptying-phase of the initial lymphatic cycle, respectively. Thus the evidence was strengthened for an hypothesis, which holds that the filling is caused by the high effective colloidal osmotic pressure of the concentrated lymph.
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PMID:A fine structural study of variations in protein concentration in lacteals during compression and relaxation. 49 38

Recycling of radioiron by renal tubular cells was studied in rats labelled by the i.v. injection of free 59Fe-Hb. Within 24 h, most of the renal radioactivity has been transferred from Hb to cellular ferritin and haemosiderin. Between day 1 and 14 of the study, urinary loss of radioactivity was less than 1% and most of the reduction in renal radioactivity represented transfer of renal iron into the circulation. An unexpected flexibility in the ability of rat kidney to recycle iron into the body has been found ranging from 13% in hypertransfused rats to 70% in bled animals. The high rate of renal iron transfer in bled animals was maintained under experimental conditions simulating chronic haemoglobinuria when most of the Hb removed by bleeding has been reinjected in the form of soluble Hb. Thus, epithelial cells in rat kidney as well as in the gut, appear to be able to transport iron with a much greater efficiency than in man, thereby contributing to the supply of iron for the rapid rates of growth and reproduction characteristic of this animal species.
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PMID:Renal salvage of haemoglobin iron. 89 59

Iron deficiency is one of the most serious nutritional problems confronting the United States and the world today. An understanding of the mechanisms operative in the control of uptake and utilization of iron is essential to develop suitable prophylactic and therapeutic strategies. Iron excess can also be a serious health hazard. Studies on Bantu siderosis, hemochromatosis and other overload pathologies also provide insight into the intake and storage of this metal. Several models for iron transport across the mucosal membrane are developed. The most satisfactory seems to involve chelation of the iron to provide solubility diffusion passively across the gut membrane, and equilibrium binding to various storage sites within the tissue. Both ferric and ferrous forms are available. The solution chemistry of iron governs its biological behavior. Low-molecular-weight compounds present in normal dietary foodstuffs, as well as those prepared synthetically, can enhance the uptake of oral iron. Suitable application of complexes of iron with fructose, nitrilotriacetate, citrate and other molecules should be efficacious in the treatment of iron deficiency anemia. Potential dangers of food fortification with iron are acknowledged, and application of immunoassay techniques for measuring circulating ferritin suggest it as a rapid and inexpensive monitor for overload.
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PMID:Tired blood and rusty livers. 125 66

The iron-responsive element binding protein (IRE-BP) is a cytosolic protein that binds a highly conserved sequence in the untranslated regions of mRNAs involved in iron metabolism including ferritin, transferrin receptor, and erythroid 5-aminolevulinate acid synthase. This conserved sequence is termed the iron-responsive element and is necessary for the post-transcriptional regulation of these mRNAs by iron. The rat liver IRE-BP was purified to homogeneity by chromatographic methods and partial amino acid sequence was obtained. A cDNA was isolated from a rat liver cDNA library and sequenced. The amino acid sequence deduced from the cDNA sequence corresponds to a protein of 889 amino acids with a predicted molecular weight of 97.946. The NH2-terminal sequence obtained by Edman degradation matched the deduced amino acid sequence obtained from the cDNA, confirming the translational start site. Rat liver IRE-BP shares 95% identity with human IRE-BP and 98% identity with mouse IRE-BP indicating that the IRE-BPs have remained highly conserved during evolution. The 5'-untranslated region is at least 236 nucleotides and contains interesting structural features including two direct repeats, an inverted repeat, and three small open reading frames. The rat IRE-BP mRNA is approximately 3600 nucleotides and is expressed in a variety of rat tissues including liver, spleen, and gut. Over the course of 16 h following an intraperitoneal injection of iron in rats. IRE-BP RNA binding activity decreases to 50% of control levels. The decrease in IRE-BP RNA binding activity in extracts from iron-treated rats is reversible by pretreatment of the extracts with reducing agents. The steady-state levels of IRE-BP mRNA remain constant during iron treatment. These data suggest that the decrease in IRE-BP RNA binding activity by iron in rat liver is due to post-translational changes in the RNA binding affinity of the IRE-BP and not due a decrease in the transcription of the IRE-BP gene or to the destabilization of the IRE-BP mRNA.
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PMID:The iron-responsive element binding protein. Purification, cloning, and regulation in rat liver. 152 27

Uptake of macromolecules (e.g., ferritin) by M cells in follicle-associated epithelium in small and large intestine was investigated in three healthy, conventionally raised, 2- to 3-week-old, female Holstein Frisian calves. A 2.5% solution of ferritin was injected into the ligated loops in mid-jejunum, in terminal ileum, in the ascending colon adjacent to the ileocecal junction, and in the proximal loop of the ascending colon containing gut-associated lymphoid tissue. After exposure times that ranged from 82 to 165 minutes, ferritin was detected in M cells of domes in the small intestine, as well as in cells in follicle-associated epithelium of proprial lymphoid nodules and lymphoglandular complexes of colon that morphologically resembled M cells of small intestine. Ferritin was found in apical invaginations, apical vesicles, multivesicular bodies, basal vesicles, and adjacent intercellular spaces. In addition to ferritin, apical vesicles, multivesicular bodies, and intercellular spaces contained 50-nm membrane-bound particles. More ferritin was endocytosed by M cells of the small intestine than by M cells of the large intestine. In the large intestine, higher amounts of ferritin were found in M cells of follicle-associated epithelium overlying proprial lymphoid nodules than in M cells of follicle-associated epithelium in the depth of lymphoglandular complexes. Based on these results, we concluded that M cells of follicle-associated epithelium in the colon of calves provide a route for antigen uptake into the intestinal lymphoid system.
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PMID:Uptake of ferritin by follicle-associated epithelium in the colon of calves. 163 55

The morphology of gut-associated lymphoid tissue and the ultrastructure of overlying lymphoepithelium of newborn and three-week-old conventionally raised calves were compared. In all calves patches of lymphoid nodules were found in the terminal rectum. In newborn calves lymphoid nodules in the submucosa with caps of lymphoid tissue in the lamina propria predominated. In three-week-old calves lymphoglandular complexes were as numerous as lymphoid nodules with caps. Scanning and transmission electron microscopical examination of superficial lymphoepithelium over caps and lymphoepithelium in epithelial diverticula of lymphoglandular complexes revealed groups or single cells morphologically resembling M cells, but with widely varying apical processes. To investigate whether these putative M cells in rectal lymphoepithelium internalise and transport macromolecules across the epithelial barrier, ferritin was injected into the rectum of three-week-old calves. Eighty to 150 minutes after exposure ferritin was detected in cells resembling M cells. Thus these cells ought to be considered as M cells. It may be hypothesised that gut-associated lymphoid tissue with specialised lymphoepithelium in the rectum of calves provides a route for the uptake of antigen.
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PMID:M cells in the rectum of calves. 189 24

The steps involved in iron absorption are poorly understood. Although transferrin and ferritin are water soluble, most radioiron in gut homogenates after an intraluminal dose of radioiron is recovered in water-insoluble precipitates. Most radioiron in the precipitates was insoluble in detergents and organic solvents and was characterized as mucins. These isolates bound iron in vitro with a Kd of 9.09 x 10(-5). Similar iron binding was observed with commercial mucins. Iron binding to mucin occurred at acid pH and maintained the iron available for absorption with alkalinization. Similar pH-dependent binding to mucin was observed with zinc, cobalt, and lead. Iron competitively inhibited binding of these metals to mucin. However, iron chelates of ascorbate, fructose, and histidine donated iron to mucin at neutral pH. These data provided a role for gastric HCl and intestinal mucin in absorption of iron and metal cations and partial explanation of the competition for absorption between certain metals from the gut lumen. It is postulated that intestinal mucin delivers inorganic iron to intestinal absorptive cells in an acceptable form for absorption.
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PMID:A role for mucin in the absorption of inorganic iron and other metal cations. A study in rats. 198 14

Lactoferrin is an iron binding glycoprotein which is abundantly present in human tear fluid. It is also present in other secretions and in the specific granules of the polymorphonuclear leucocyte. The main biological properties of lactoferrin can be ascribed to its very strong binding of iron cations. Receptors for lactoferrin have been found in the intestinal brush border, suggesting that it may play a role in iron absorption from the gut. Macrophages also have a receptor for lactoferrin, which are possibly involved in the transfer of iron to ferritin. More important may be the fact that deprivation of iron from the gut or from the ocular surface limits the availability of iron to microorganisms and thus exerts firm control of the bacterial flora at these sites. Sequestration of iron by this protein can also inhibit the iron catalyzed production of hydroxyl radicals thereby protecting mucosal surfaces from oxydative damage. Lactoferrin has furthermore been shown to play a role in myelopoiesis, primary antibody response, lymphocyte proliferation, cytokine production, ADCC, NK cell activity, and regulation of complement activation. The observations described above indicate that lactoferrin, besides control of the bacterial flora, may regulate inflammatory reactions occurring on the ocular surface.
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PMID:The role of lactoferrin in the nonspecific immune response on the ocular surface. 212 4


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