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

Plasmalemmal differentiation of the enucleating normoblast of rabbit and rat was studied by means of cytochemical methods and freeze-etching. Staining with colloidal iron revealed about identical amounts of iron particles bound to various areas of the normoblast membrane. Cationized ferritin and ruthenium red, likewise, failed in the demonstration of significant changes of the enucleating normoblast glycocalyx. Despite these findings the topo-optical staining with toluidine blue showed the plasmalemmal envelope of the protruding normoblast nucleus moderately birefringent, clearly discriminated from the intense anisotropic staining of the future reticulocyte membrane. The ferritin-labeled snail lectin anti AHP localized a great number of binding sites at the plasmalemmal envelope of the nucleus under extrusion. That is in sharp contrast with rather low lectin binding to the future reticulocyte membrane which amounts to about 30 to 50% of the nuclear envelope label. The findings provide evidence of unmasking of bindings sites of the normoblast membrane. Apparently, the effect is due to conformational changes of the cell membrane, rather than it could be attributed to degradation of glycoproteins. Moreover, enucleation kinetics may also be related to supramolecular changes of membrane structure albeit missing evidence for the rearrangement of membrane particles.
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PMID:Alteration of the enucleating erythroblast glycocalyx. 11 25

Since the trophoblast-uterine adhesion is as nearly a universal phenomenon in implantation as can be found, an attempt was made to determine whether or not there was a reduction in cell surface glycoproteins in the rat, as can be observed in the ferret. Neither colloidal iron nor cationized ferritin revealed the type of pattern anticipated for a localized reduction in surface negativity in the imprint of the blastocyst in the implantation chamber. The use of lectin-coated latex beads also proved disappointing in defining regional differences in adhesiveness. However, a number of observations on the changing shape of the implantation chamber, the secretion of periluminal material by decidual cells, and the penetration of the residual basal lamina of the luminal epithelium by the decidual cells were made in the course of these studies. The implantation chamber of the rabbit, in which the blastocyst does not make an imprint, was contrasted with that of the rat. The areas of fusion of trophoblast knobs with uterin epithelial cells shown to be visible by scanning electron microscopy. Finally, some observations on the hypertrophy of maternal epithelial cells to form the uterine plaque in the rhesus monkey are described, and the hypertrophy of endothelial cells to form admirably suited to protein secretion is presented.
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PMID:Comparative aspects of blastocyst-endometrial interactions at implantation. 11 57

Serogroups of N. meningitidis were characterized as virulent or avirulent according to their capacity to establish meningococcal infection in mice. An agar plate diffusion technique demonstrated that iron had a definite growth-supporting role for both of these meningococcal types. The avirulent strains could use ionic or chelated iron as well as the virulent strains. Iron-reversible growth inhibition occurred to the same extent for both bacterial types in the presence of the synthetic iron-chelating agents Desferal and ethylenediamine-di-orthohydroxy phenylacetic acid. A difference in response was demonstrated for these bacterial types when grown in the presence of various iron-binding proteins from animal body fluids and tissues. The growth of the avirulent strain was inhibited to a greater degree by egg white conalbumin. The humoral iron-binding protein transferrin showed a significant inhibitory capacity only when used in conjunction with bicarbonate. Under conditions of increased iron saturation of this protein, the avirulent strain was inhibited to the furthest extent. In the presence of ferritin, the cellular iron-binding protein, which had been reduced, inhibition of the growth of either strain type did not occur on iron-poor media (less than 5 micrograms/100 ml). However, with the incorporation of iron into the media, the inhibitory effect of the protein became evident. As the concentration of iron increased, the inhibition increased to a certain level and subsequently declined. A substantial difference in the ability of the avirulent type to grow in the presence of reduced horse spleen ferritin was observed. For this microorganism, a correlation appears to exist between the capacity to grow by utilizing the available iron in the presence of reduced ferritin and the ability to establish infection. The host protein ferritin, in the reduced state, apart from simply being a storage protein for iron, can prevent the growth of a procaryotic organism. Our experiments suggest a role for ferritin in the prevention of emningococcal disease. A cehmotherapeutic potential for Desferal is also implied.
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PMID:Inhibition of the growth of Neisseria meningitidis by reduced ferritin and other iron-binding agents. 11 92

The nature of the factor in Hodgkin's disease involved spleen to which many patients with malignant lymphoma react in the leucocyte migration inhibition test has been investigated. Our results suggest that ferritin from Hodgkin's disease involved spleens is antigenically different to that prepared from normal spleen. Isoelectric focusing shows the presence of more acidic 'isoferritins' in ferritin prepared from Hodgkin's disease involved spleen than in that prepared from normal spleen. Further observations using the leucocyte migration inhibition test suggest that sensitization to the abnormal ferritin, acting as an onco-fetal tumour associated substance, may be responsible for the reaction of patients with malignant lymphoma in this test.
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PMID:Ferritin, a sensitizing substance in the leucocyte migration inhibition test in patients with malignant lymphoma. 11 71

The endocytic vacuoles induced in white ghosts were found to be depleted of spectrin and therefore it was proposed that they arose from spectrin-free areas in the erythrocyte membrane. To follow changes in spectrin distribution during endocytosis, affinity-purified rabbit antispectrin antibodies were produced. Quantitative techniques were developed for the use of a highly specific 125I-F(ab')2 antispectrin, and these showed that before the appearance of vacuoles, as assessed by phase microscopy, there was a reproducible decrease in immunoreactive spectrin. To determine whether this spectrin decrease represented a local or diffuse spectrin loss or a spectrin rearrangement, morphologic studies were undertaken using transmission electron microscopy on samples treated with rabbit antispectrin and ferritin-conjugated goat anti-rabbit immunoglobulin. These studies showed that endocytosis was preceded by the creation of extensive spectrin-free areas separated by discrete spectrin-containing zones. Pretreatment of ghosts with alkaline phosphatase blocked all forms of endocytosis and prevented the creation of spectrin-free areas. Therefore, it is proposed that under the impetus of endocytosis inducers, phosphorylated spectrin is redistributed so that spectrin-free zones are created, and that endocytic vacuoles form and fuse in spectrin-free areas.
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PMID:Spectrin rearrangement early in erythrocyte ghost endocytosis. 11 12

The surface charge of cultured neurons was investigated with the electron microscope markers anionized ferritin (AF) and cationized ferritin (CF). To determine which membrane components could react with the markers, model reactions were used. Both protein-coated Sepharose beads and lipid vesicles were reacted at physiological pH. Results with these model reactions indicate that the following groups may contribute to the surface charge: acidic groups--the sialic acid of both glycoproteins and gangliosides, the carboxyl group of proteins, and the phosphates of phospholipids; basic groups--the amines of proteins. The effect of chemical fixation on the surface charge was investigated. Glutaraldehyde fixation was shown to increase the charge of neutral proteins but not by a mechanism involving unbound aldehydes. Glutaraldehyde fixation of phospholipid vesicles in the presence of CF showed that amine-containing phospholipids were cross-linked to CF. This cross-linkage was seen with the electron microscope as the clumping of CF and the burying of CF in the membrane. Paraformaldehyde fixation had a lesser effect on the charge of proteins but did react with phospholipids as did glutaraldehyde. It is concluded that at physiological pH: (a) most of the charged proteins and lipids on cell surface can contribute to the membrane surface charge, and (b) the membrane surface charge of cells can be greatly changed by chemical fixation.
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PMID:Contributions of lipids and proteins to the surface charge of membranes. An electron microscopy study with cationized and anionized ferritin. 11 15

Ferritin has been purified from normal full-term human placentae and its antigenic and molecular characteristics compared with adult liver ferritin. Placental ferritin is composed predominantly of a single subunit type, co-migrating with a liver ferritin standard on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Comparison of dose-response curves in an immunoradiometric assay indicated some tissue-specific antigenicity for placental ferritin. This was supported by immunofluorescence studies on cryostat sections of human placentae by using antibodies to placental and spleen ferritin. Specific staining for placental ferritin was demonstrated within placental syncytiotrophoblast, particularly localized towards the microvillus plasma membrane. Ferritin has also been shown by electrophoretic and antigenic analysis to be present in protein fractions solubilized from isolated human syncytiotrophoblast microvillus plasma-membrane preparations, suggesting that ferritin may play an active role in the transfer of iron from maternal transferrin across the syncytiotrophoblast plasma membrane.
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PMID:Characterization and localization of human placental ferritin. 11 99

The value of serum ferritin and mean corpuscular volume (MCV) measurement in distinguishing between iron deficient, beta-thalassaemia trait and normal subjects has been studied. Normal subjects had normal ferritin and MCV, iron-deficient ones had low ferritin and low or normal MCV, and thalassaemics had normal ferritin and low MCV. By the combined use of these two measurements it was possible to identify individuals belonging to one of the three categories with an accuracy of over 95%. Although definitive diagnosis of beta-thalassaemia trait requires the demonstration of abnormal haemoglobin A2 levels or reduced beta-chain synthesis, serum ferritin and MCV measurements are useful screening procedures for the initial diagnosis of beta-thalassaemia trait and iron deficiency. Because of the very small amounts of blood required for both of these measurements, they are particularly suitable for surveying large numbers of subjects in populations with a high prevalence of hypochromic-microcytic anaemias.
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PMID:Serum ferritin and mean corpuscular volume measurement in the diagnosis of beta-thalassaemia minor and iron deficiency. 11 17

The immunolabeling characteristics of Rickettsia tsutsugamushi (Gilliam strain) were examined by using a purified immunoglobulin G fraction of antibody to R. tsutsugamushi raised in rabbits. Formalin-fixed rickettsiae were reacted with this antibody and then with ferritin-conjugated goat anti-rabbit Fc antibody. R. tsutsugamushi cultivated in yolk sacs was used to raise antibody for this study. When rickettsiae in BHK-21 cells infected from yolk sac seed material were immunoferritin labeled, the binding of ferritin was found to be dense and uniform on the outer surface of the rickettsiae in disrupted host cells. Immunolabeling of purified suspensions of extracellular rickettsiae resulted in the uniform ferritin labeling of the microorganism. Aggregation of these rickettsiae by antibody appeared to depend upon the purity of the pellets. Immunoferritin labeling examined at high magnification revealed ferritin very close to the outer dense leaflet of the outer membrane. On some rickettsiae or on focal sites of others, the labelin; was several ferritin particles thick, suggesting the presence of a thick coating. The immunoferritin labeling of R. tsutsugamushi during successive serial passages in BHK-21 cells revealed decreased labeling with each passage, and by the 10th passage there was no detectable labeling. However, these rickettsiae inoculated back into yolk sacs regained their immunoferritin labeling. R. tsutsugamushi passed back into yolk sacs after four serial propagations in BHK-21 cells regained their labeling on the first passage in yolk sacs. However, rickettsiae from the 20th serial passage in BHK-21 cells required five passages in yolk sacs to reestablish their previous labeling affinity. Rickettsiae which did not label after 20 passages in BHK cells regained some of their labeling characteristics when sonicated. Antibody against rickettsiae cultivated in BHK-21 cells continued labeling rickettsiae even after 9 serial passages in BHK-21 cells.
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PMID:Changes in immunoferritin labeling of Rickettsia tsutsugamushi after serial cultivation in 60Co-irradiated BHK cells. 12 Nov 11

In view of the reported associations of Hodgkin's disease and ferritin, an electron microscopic study of the peripheral blood lymphocytes of these patients was done. In 5 out of the 6 patients studied intracellular ferritin deposits were seen. No such deposits were seen in the lymphocytes of healthy subjects or in those of a patient with beta-thalassemia. The lymphocyte ferritin accumulation in Hodgkin's disease can arise either from increased synthesis or from phagocytosis.
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PMID:Ferritin deposits in peripheral blood lymphocytes of Hodgkin's disease patients. 12 68


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