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

Feeding of baboons with crocidolite showed small numbers of asbestos needles 0.5-1 mum in ashed tissue of the gut wall, which probably came from iron-containing macrophages. It is suggested that pleural plaques and hyaline nodules in the peritoneum represent a hypersensitivity reaction to ferritin protein coating on asbestos fibers. In South Africa only a few peritoneal mesotheliomas come from the asbestos areas, and the incidence of gastrointestinal carcinomas is no greater than normal. Intrapleural and intraperitoneal injection produces unrealistic situations. Calcium salts are deposited on asbestos cement pipes from hard water and organic material from soft water. It is difficult to envisage asbestos contamination of the water so reticulated.
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PMID:The ingestion of asbestos fibers. 447 Sep 36

A method is described for determining the two-dimensional distribution of specific antigens on cell surfaces, and is applied to the D antigen of the Rh antigenic system. Rh-positive human erythrocytes are allowed to react with purified (125)I-labeled human anti-Rh(o)(D) gamma-globulin antibodies, and the sensitized cells are then lysed at an air-water interface. The residual cell membranes are spread flat by surface forces, and are picked up on a carbon-strengthened collodion-coated electron microscope grid. The membranes are then stained with ferritin-conjugated goat antibodies directed against human gamma-globulins. Only Rh-positive cells sensitized with anti-Rh(o)(D) antibodies bind the ferritin-conjugated antihuman gamma-globulins. The ferritin particles are found in small clusters on the membrane surface, and the number of such clusters per unit area agrees with the number of (125)I-labeled anti-Rh(o)(D) antibodies bound per unit area. The Rh(o)(D) antigenic sites appear to be molecularly dispersed on the membrane surface, but in a random two dimensional array.
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PMID:Quantitative two-dimensional ultrastructural distribution of Rh o (D) antigenic sites on human erythrocyte membranes. 499 56

The structure and distribution of pulmonary lymphatics and their permeability to fluids and particulate materials have been investigated in the lungs of rats following fixation by combined intratracheal and vascular perfusion. In such preparations, the lymphatics remain in a distended state, and a close relationship to other structural components of the pulmonary interstitium is maintained. They were identified in regions with an abundant amount of connective tissue, forming an eleborate plexus within the pleura, the interlobular septum, peribronchial and perivascular areas. Recent data have shown that water-soluble molecules and particulate matter are removed from the interstitium along the lymphatic capillary (initial lymphatics) segment. It is distinguished by attenuated endothelial cells with extensively overlapping cell margins which are easily separated. We have studied this segment of the lymphatic vascular system following intratracheal injections of colloidal particles (ferritin and carbon) to determine the structural features responsible for the transport of large molecules and particulate materials across the lymphatic endothelial wall in the lung. The results showed that the tracer particles cross the lymphatic endothelial wall via the clefts of intercellular junctions. While the tracer particles were observed within vesicles, the question of transport across the lymphatic endothelium via plasmalemmal vesicles is still not settled since the number and size of vesicles containing tracer particles also increased with time. Intravascular injected dextran was also localized within the clefts of intercellular junctions and plasmalemmal vesicles. The results obtained with intratracheal and intravascular injected tracer substances are consistent with those observed in lymphatic capillaries for other tissues.
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PMID:Lymphatic removal of fluids and particles in the mammalian lung. 615 24

In the bone-marrow, non-haemoglobin iron can predominantly be found in the reticulum. Slight granules containing iron can also be observed in parts of erythroblasts by means of the Berlin blue reaction. These cells are called sideroblasts. In chemical respect, non-haemoglobin iron consists of ferritin soluble in water and haemosiderin insoluble in water. Erythroblasts will only take their iron from plasma transferrin. For the most part, this iron uptake is being regulated by erythropoietin adapting erythropoiesis to the oxygen requirements of the tissue. The iron contained in erythroblasts is predominantly utilized for haemoglobin synthesis in these cells. A slight part is being taken up by ferritin. The bone-marrow reticulum will phagocytise aged erythrocytes and store liberated iron as ferritin and haemosiderin. Part of the iron is being delivered again to plasma transferrin. With constant serum iron level the liberation of iron from the reticulo-endothelial tissue must correspond to the iron uptake by erythropoiesis. The absence of iron capable of being coloured in the bone-marrow reticulum is considered to be a reliable parameter of iron deficiency. It enables the diagnosis of iron deficiency anaemia to be made even in those patients with serum iron level and a total iron binding capacity lying within the normal range and no hypochromia of erythrocytes being present. It enables iron deficiency anaemia to be separated from sideropenic anaemia with reticulo-endothelial siderosis in differential-diagnostic manner. Even in patients with sideroblastic anaemia, iron colouring of bone-marrow smears is required for ensuring the diagnosis. Recently, a separation has also been made for idiopathic anaemia with abnormal sideroblasts. In these patients there is an increased risk for acute leukemia to develop.
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PMID:[Iron in bone marrow]. 618 56

Within the epithelium that overlies the dome regions of Peyer's patches, exist specialized surface epithelial cells (M) which function to take up macromolecules from the gut lumen. These cells may be of great importance in processing antigenic material in the gut. The predominant lymphoid structures of the small intestine are isolated lymphoid follicles, by virtue of their frequency. These follicles are difficult to study because they are not grossly visible. In the present study, three guinea pigs drank India ink mixed into their water for 1, 3, and 5 months. Two hours prior to sacrifice, animals were given an intraintestinal injection of ferritin or India ink. Using a hand lens, the Peyer's patches and isolated follicles were clearly identified among the villi of the intestine. Light microscopy revealed ink in the surface epithelium covering the isolated follicles and within the substance of the follicles. Transmission electron microscopy demonstrated M cells over isolated follicles and Peyer's patches. These cells had lighter staining cytoplasm, while the mitochrondria stained darker with prominent cristae, and the microvilli were shorter. Therefore, M cells do exist within isolated follicles and structurally appear the same as those found in Peyer's patches. This implicates the isolated follicles in the overall antigen processing role of gut-associated lymphoid tissues. The present method facilitates identification of isolated lymphoid follicles which will allow functional studies to be performed on these structures.
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PMID:Demonstration of M cells in the specialized follicle-associated epithelium overlying isolated lymphoid follicles in the gut. 620 May 55

The effectiveness of N,N'-bis[2-hydroxybenzyl]-ethylene-diamine-N,N'-diacetic acid (HBED) in removing radioiron introduced into the parenchymal cells of mouse liver as 59Fe-ferritin has been investigated. The effectiveness of HBED, an iron chelator of low water solubility, has also been compared with that of desferrioxamine (DF), an iron chelator of high water solubility and currently in clinical use for treatment of transfusional iron overload. Using the 59Fe excretion as the measure of effectiveness of chelation therapy and a standardized single chelator dose of 25 mg/kg, we have found that: (1) a saline suspension of HBED, prepared by sonication and given intraperitoneally to mice, promotes a small but significant increase in excretion of radioiron compared to the untreated controls, whereas DF, in its free form, is ineffective; (2) HBED encapsulated in lipid bilayers of liposomes and given intravenously is superior to nonencapsulated HBED; (3) DF encapsulated in small unilamellar liposomes is ineffective in removing iron given in the form of ferritin; (4) administration of phenobarbital in drinking water, at a concentration of 1 g/liter, induces a 30%-55% increase of iron excretion from untreated control mice and also from mice given HBED either in liposome-encapsulated or nonencapsulated form. We have demonstrated that HBED is superior to DF for removal of storage iron from liver parenchymal cells and that liposomes are useful carriers for iron chelators of low water solubility.
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PMID:Enhanced iron removal from liver parenchymal cells in experimental iron overload: liposome encapsulation of HBED and phenobarbital administration. 640 48

Three insect tissues have particular roles as filters to maintain the fluid composition of the hemolymph. Water and ions enter and leave through the midgut. The pericardial cells filter circulating hemolymph. Malpighian tubules, often with the rectum, allow resorption from a hemolymph filtrate that passes to the hindgut. All three tissues have plasma membrane infolds making a reticulum on their hemolymph surfaces, and all three have RER leading to SER extensions into their reticula. SER is a catch-all description for membranes lacking ribosomes in the pre-Golgi complex set of compartments of the vacuolar system. Some kinds of SER are well known for their role in housing enzymes for steroid metabolism and for detoxification. The SER ramifying within the plasma membrane reticular systems of tissues concerned with hemolymph filtration contains ferritin, suggesting that this SER has another, different function. In contrast to vertebrate cells, where ferritin is confined to the cytosol and lysosomes, we have found that in Calpodes and perhaps in most insects, ferritin occurs in the vacuolar system and not in the cytosol. Ferritin occurs naturally in the RER and SER of cells at the hind end of the midgut, in pericardial cells and in the yellow region of the Malpighian tubules. Additional ferritin is induced by loading the gut or hemolymph with iron. Overloading with iron causes ferritin secretion to the gut lumen. We propose that the SER in these cells functions in iron homeostasis by holding ferritin for loading and unloading as it moves to and from the reticulum at the cell surface where it can be maximally exposed to extracellular fluid flow.
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PMID:The induction and distribution of an insect ferritin--a new function for the endoplasmic reticulum. 651 41

To investigate whether certain macromolecules reduce capillary permeability by binding to the surface coat of endothelial cells, the effects of cationised ferritin (CF) upon the filtration coefficient (Lp) of individually perfused frog mesenteric capillaries were compared with those of native ferritin (NF). With perfusate CF concentrations between 0.1 g 100 ml-1 and 2.5 g 100 ml-1, Lp was reduced to approximately 30% of its value for the same vessel perfused with protein-free Ringer solution. Electron micrographs of the perfused capillaries revealed that over this range of perfusate concentrations. CF was concentrated uniformly in the endothelial cell coat, occupying 8.5% of its volume. Neither the effect of cationised ferritin upon Lp nor its concentration in the cell coat varied significantly over this range of perfusate concentrations. When perfusate concentration of CF was reduced to 0.01 g 100 ml-1, CF no longer reduced Lp and its concentration in the cell coat fell below 2%. Native ferritin, which is excluded from the cell coat, did not reduce Lp at a perfusate concentration of 0.1 g 100 ml-1. At a concentration of 2.5 g 100 ml-1, NF reduced Lp in a few very permeable vessels (Lp greater than 60 X 10(-3) microns sec-1 cm H2O-1) but had no significant effect on vessels with lower and more normal values of Lp. The effects of CF upon Lp can be described in terms of the Kozeny equation if a major proportion of the hydraulic resistance through the capillary wall is attributed to a fiber protein matrix.
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PMID:The effects of cationised ferritin and native ferritin upon the filtration coefficient of single frog capillaries. Evidence that proteins in the endothelial cell coat influence permeability. 684 73

In a series of pregnant women with iron deficiency anaemia treated by a total dose infusion of iron dextran, the non-haem iron content of the placenta at term was studied histochemically and by chemical analysis. Within a few days of the infusion the Prussian blue reaction on the placenta was very strong, but was negative by ten days after the infusion. Chemical analysis showed that both the water-insoluble fraction (haemosiderin) and the water-soluble fraction (ferritin) of the non-haem iron were increased soon after the infusion, but three weeks after the infusion they were almost the same as in untreated controls. Pinocytosis of iron dextran by the trophoblast and increased transport of transferrin-bound iron to the placenta are considered as possible causes for this large uptake of iron by the placenta.
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PMID:Effect of total dose infusion of iron dextran on the storage iron content of the human placenta. 708 94

The filamentous bacteriophage f1 can be transformed into a spherical particle (spheroid) or an intermediate shortened filament with a flared end (I-forms) by exposure to a chloroform-water interface at 22 or 4 degrees C, respectively. The protein composition of bacteriophage f1 spheroids and I-forms was examined by separating the proteins from the purified. [35S]cysteine-labeled particles by sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis. Quantitation of the radioactivity on the gels showed that I-forms and spheroids contain the same complement of minor coat proteins as do untreated f1 phage. This composition is unchanged after removal of the DNA, either by digestion with micrococcal nuclease or by centrifugation of the particles through CsCl density gradients, indicating that none of the minor coat proteins is held in the particles solely through an interaction with the DNA. We also examined the location of the A protein in I-forms by decoration with ferritin-conjugated antibodies and examination under the electron microscope and found that the A protein is located specifically at the flared end of the I-form particle, through which the DNA is extruded and at which contraction into spheroids begins. The implications of these results with regard to the orientation of the DNA within the capsid and the process of infection are discussed.
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PMID:Minor coat protein composition and location of the A protein in bacteriophage f1 spheroids and I-forms. 709 58


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