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)

Surface charge of Leishmania mexicana amazonensis was investigated by direct zeta-potential determination and ultrastructural cytochemistry, and its surface tension was studied by measurements of the advancing contact angle formed by the parasite monolayers with drops of liquids of different polarities. Both virulent and avirulent promastigotes exhibited negatively charged surfaces with a zeta-potential of about -15 mV. Treatment of these cells with trypsin, alkaline phosphatase, or phospholipase C rendered their surfaces less negatively charged, whereas neuraminidase did not alter the parasite negativeness. Cytochemically, we could observe a reduction in the cationized ferritin binding after the parasite treatment with each of the former enzymes, but not with neuraminidase. The surface free energy of parasites was calculated by taken to account the London dispersion, the Keeson dipole-dipole, and the Debye dipole-induced forces, as well as the surface polarity of the parasites and their zeta-potentials, by considering their adhesion to polystyrene surfaces. The delta G values of -6.4 and -18.1 mJ.m-2 were obtained for avirulent and virulent promstigotes, respectively.
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PMID:The surface free energy of Leishmania mexicana amazonensis. 170 80

In order to determine if there are biochemical changes in plasma-membrane oligosaccharides of regenerating retinal pigment epithelium, the binding of colloidal iron oxide at low pH and ferritin-conjugated wheat germ agglutinin--probes of sialic acid and N-acetylglucosamine on the cell surface--was examined electron-microscopically. An animal model of retinal pigment epithelium regeneration--rabbits with sodium iodate induced retinopathy--was used. In this model, large expanses of regenerating pigment epithelium are present for comparison with zones of spared pigment epithelium in the same animals. In thin sections examined by transmission electron microscopy, ferritin-conjugated wheat germ agglutinin appeared to bind more intensely to the exposed plasma membrane of regenerating retinal pigment epithelium than to spared pigment epithelium, or that of normal rabbits. Morphometry verified this. Colloidal iron oxide intensely labelled the plasma membranes of regenerating, spared, and normal pigment epithelium, and was visibly reduced after exposure of tissue to neuraminidase. The observations indicate that the plasma membrane of regenerating retinal pigment epithelium bears sialic acid and N-acetylglucosamine residues as in normal retinal pigment epithelium. However, the amount of plasma membrane bearing exposed N-acetylglucosamine increases during regeneration.
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PMID:Labelling of regenerating retinal pigment epithelium by colloidal iron oxide and ferritin conjugated to wheat germ agglutinin. 205 36

To evaluate the effect of biochemical modifications not possible in vivo, filters of dog glomerular basement membrane (GBM) were constructed in ultrafiltration cells in vitro. The sieving coefficients (SCs) of three protein markers of differing size and charge (native, anionic bovine albumin-BSA; cationized BSA-cBSA; and immunoglobulin G-IgG) were determined using filters of differing amounts of control GBM, and under varying transmembrane pressures (delta P). Flow rates did not increase proportionately with increasing delta P, indicating filter compressibility. Protein SCs did not change with changing delta P, but did decrease with increasing filter thickness. Control filters showed a small but definite charge selectivity (SCcBSA++ - SCBSA greater than 0); a much greater degree of size selectivity (SCcBSA - SCIgG) was observed. Hexadimethrine (HDM), a polycation which causes proteinuria in vivo, led to marked increases in protein SCs. In contrast, removal of the major population of intrinsic GBM negative charges by carboxyl group methylation only produced a small increase in the filtration of BSA, with no change in filtration of cBSA or IgG. Other biochemical modifications (heparinase or neuraminidase treatment) had no effect on filter permselectivity. Carboxyl group methylation essentially abolished filter binding of cationized ferritin, which showed substantial binding to control filters. These in vitro studies provide confirmatory evidence for a direct effect of HDM on the permselective properties of GBM. In addition, biochemical modification studies suggest a fundamental difference between the binding of an exogenous polycation to GBM anionic sites and the removal of intrinsic charges.
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PMID:Macromolecular sieving by glomerular basement membrane in vitro: effect of polycation or biochemical modifications. 207 68

By using colloidal iron and polycationic ferritin at low pH (1.8 and 1.9, respectively) as electron histochemical stains, we localized sialic acid moieties in the trabecular meshwork of normal human eyes. The markers were distributed continuously over the entire surface of the trabecular cells, but were localized linearly as well as randomly in the basal lamina. Within the beams, the markers were located irregularly in the collagen core, but were absent from the elastic tissue and from the 100 nm banded structures in the cortical zone. Pretreatment of the tissue with neuraminidase abolished this staining which indicates that sialated moieties are present in the stained structures. Biochemical analysis with the lectin Limax flavus agglutinin revealed that the major sialated polypeptides in individual samples of human trabecular meshwork migrated at apparent molecular weights of 56, 75, 95, 128, 140, 180 and 220 kDa under reducing conditions. The fractions at approximate molecular weights of 180 and 220 kDa include the sialoglycoproteins thrombospondin and fibronectin, respectively. The total content of sialic acid in the human trabecular meshwork (patient age range, 27-57 yr) was 3.6 +/- 0.6 mumol g-1 wet weight, as determined by a colorimetric assay. We conclude that significant quantities of sialic acid are present in the normal human trabecular meshwork as neuraminidase-sensitive alpha-ketosidically linked terminal residues of the polypeptides.
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PMID:Qualitative and quantitative analyses of sialic acid in the human trabecular meshwork. 224 33

We report a case of malignant histiocytosis diagnosed by liver-spleen biopsy under laparoscopy. A 49-year-old woman was admitted to our hospital with thrombocytopenia, moderate anemia and hypoproteinemia. Her bone marrow findings revealed erythroid and megakaryocyte hyperplasia, and the serum ferritin concentration was 2,250 ng/ml though she had not received any blood transfusions. Ferrokinetics analysis showed the pattern of ineffective erythropoiesis, and the half-lives of erythrocytes and platelets were both shortened. Her hepatosplenomegaly gradually increased accompanied by increasing serum ferritin level to 10,000 ng/ml. Liver-spleen biopsy was carried out under laparoscopy and revealed infiltration of atypical histiocytes with erythrophagocytosis, which were positive for S-100 and ferritin but negative for lysozyme. The rate of glycosylation in whole serum ferritin, analyzed by using concanavalin-A binding method, showed that her glycosylated ferritin content was only 8.3%, whereas in sera after iron overloading, it was about 70%. Serum isoferritin profiles by isoelectric focussing were studied, and isoferritin pattern from malignant histiocytosis was the same as that in iron overloading after neuraminidase treatment. These findings suggest that serum ferritin is synthesized in proliferating histiocytes and released in the plasma as a nonsecretory type (nonglycosylated ferritin) in this case.
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PMID:[Mechanism of hyperferritinemia in a case of malignant histiocytosis]. 238 9

The surface charge of Toxoplasma gondii tachyzoites was evaluated by means of binding of colloidal iron hydroxide particles at pH 1.8, cationized ferritin particles at pH 7.2 and ruthenium red to the cell surface, as visualized by electron microscopy and by direct measurements of the electrophoretic mobility (EPM) of the cells suspended in solutions of different ionic strength and pH. At pH 7.2, T. gondii has a negative surface charge with a mean EPM of--1.1272 +/- 0.0917 micron.s-1 X V-1 X cm. No significant difference was observed between the EPM of living cells at 25 degrees C and that of glutaraldehyde-fixed cells. At lower pH, there is a decrease in the negative surface charge, with an isoelectric point at pH 3.5. At higher pH (greater than 10), there is an increase in the surface charge reaching an EPM of--1.5675 +/- 0.0848 micron.s-1 X V-1 X cm at pH 7.2. These results indicate that the surface of T. gondii contains both negatively and positively charged dissociating groups. Binding of cationized ferritin particles and ruthenium red throughout the cell surface of glutaraldehyde-fixed cells was observed. However, when living parasites were incubated at 4 degrees C in the presence of cationized ferritin some cells showed a uniform distribution of the label, others showed a patch-distribution and still in others no label was seen, indicating a process of mobility and shedding of surface anionic sites. Colloidal iron hydroxyde particles did not bind to the surface of T. gondii. Incubation of the parasites in the presence of neuraminidase from Clostridium perfringens or Vibrio cholerae or in the presence of proteolytic enzymes (trypsin or protease) did not interfere with the surface charge.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The surface charge of Toxoplasma gondii: a cytochemical and electrophoretic study. 243 Nov 57

The reasons for greater lung vascular permeability to anionic macromolecules are not understood. In order to determine whether the luminal or abluminal surfaces of lung capillary endothelial cells differ with respect to surface charge, we compared the binding of cationic ferritin, an electron dense probe, with these cell surfaces in lung capillaries. Because lung capillaries are not normally permeable to cationic ferritin, lungs were examined from rats with increased permeability edema caused by pretreatment with alpha-naphthylthiourea (ANTU). We found that more cationic ferritin particles bound to the luminal than to the abluminal surfaces of lung capillary endothelium. In order to determine whether this was due to inaccessibility of cationic ferritin to the lung interstitium, we also compared cationic ferritin binding to the apical and basal surfaces of bovine calf aortic and main pulmonary arterial endothelial cells in tissue culture. We found that more cationic ferritin bound to the apical than to the basal surface of the cultured cells. The binding of cationic ferritin to cultured endothelial cells was due to charge since native, anionic ferritin did not bind to either surface and binding was decreased by neuraminidase pretreatment of cultures. Cultures incubated with thiourea, another thiocarbamide that causes increased permeability edema in vivo, also showed greater binding of cationic ferritin to the apical cell surface, suggesting that the differences seen in vivo were not due to thiocarbamide injury. However, another cationic probe, ruthenium red, bound to both the apical and basal surfaces of cultured endothelial cells. These results suggest that the basal endothelial cell surface does not lack anionic sites.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The binding of cationic probes to apical and basal surfaces of rat lung capillary endothelium and of endothelial cells in tissue culture. 243 98

Picric acid-paraformaldehyde-glutaraldehyde (PA-P-G) was used to stabilize chemically ocular surface-associated mucus in mice of various ages. Transmission electron microscopy was then used to examine those specimens stained with cationic ferritin (CF), dialysed iron and Alcian Blue. Collectively, all of these stains are markers for anionic sulfate or carboxyl groups. With each of them, positive labeling of the ocular surface was observed for all ages examined, even when mucus cannot be morphologically demonstrated. Except for dialysed iron, staining was weak in the youngest animals and heaviest in young adult and aged mice. The ocular surface was negative for high iron diamine (HID) in pups and older mice through 1 year of age. Scant positive staining for HID was seen at the ocular surface in 14-month-old mice indicating that mucus became slightly sulfated with aging. Treatment of eyes with neuraminidase prior to fixation reduced the number of CF binding sites in all ages of mice examined, confirming that many of the carboxyl groups at the ocular surface are associated with sialic acid residues. Comparison of percentage reduction in CF labeling following neuraminidase treatment of the eyes of 5- and 10-postnatal day mice with all other ages of mice suggested that fewer removable carboxyl groups at the ocular surface are associated with sialic acid residues in pups. The ocular surface of all eyes also stained positively at the TEM level when a periodic acid-thiocarbohydrazide-silver protein (PA-T-SP) staining sequence was used. Collectively, these data are of significance with respect to further characterization of the ocular surface, particularly with regard to development-associated changes and their possible role in defence of the eye surface.
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PMID:Ocular surface complex carbohydrates are modified with aging. 243 68

The surface anionic groups of untreated or dimethyl sulfoxide (DMSO)-treated Herpetomonas samuelpessoai cells were analyzed by cell electrophoresis, ultrastructural cytochemistry, and identification of sialic acids using thin-layer chromatography. Differentiation of H. samuelpessoai induced by DMSO treatment caused a significant increase in the net negative surface charge. In flagellates exposed to DMSO, more cationized ferritin, colloidal iron hydroxide, and sendai virus particles bound to the cell surface. Treatment of both untreated and DMSO-treated flagellates with neuraminidase decreased markedly the EPM of cells to the cathodic pole. These findings suggest that sialic acid residues are the major anionogenic groups exposed on the surface of H. samuelpessoai. Thin-layer chromatography showed that N-acetyl and N,O-diacylneuraminic acids, in equal proportions, were present in H. samuelpessoai. However, N-acetylneuraminic acid predominates in DMSO-treated cells.
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PMID:Changes in cell surface anionogenic groups during differentiation of Herpetomonas samuelpessoai mediated by dimethylsulfoxide. 245 50

A monoclonal antibody, OVB1, was generated against a human ovarian carcinoma cell line, OVCAR-3. The antigen reacting with this antibody was strongly expressed on the external surface of the plasma membrane of OVCAR-3 cells and cells of 4/4 other ovarian carcinoma lines. Variable density and homogeneity of expression was found on cells from 5/5 breast carcinoma lines. Various ovarian tumor specimens and normal human tissues were frozen, cryostat-sectioned, and examined for OVB1 reactivity using immunoperoxidase methods. A strong, uniform, homogeneous reaction on 10/10 ovarian carcinoma specimens and variable, non-homogeneous reactions on breast tumors were seen. Normal tissues reacting with the antibody include thyroid, pituitary pars intermedia, breast ductal epithelium, Auerbach's plexus and neuronal processes in the GI tract, colonic mucosal epithelium, and salivary gland ductal epithelium. Polymorphonuclear leukocytes, eosinophils, and approximately 13% of peripheral lymphocytes, as well as cells around germinal centers in lymph nodes and spleen, showed strong reactivity by immunofluorescence and/or immunoperoxidase. Expression of the OVB1 antigen in the myeloid cells of normal human bone marrow occurred from the promyelocyte stage through to more mature cells in a subpopulation of myeloblasts. Indirect immunofluorescence of live peripheral blood cells showed localization to the surface of PMNs, eosinophils, and certain lymphocytes. Double-immunofluorescence studies (with a direct fluorescein-anti-lactoferrin antibody conjugate) showed co-localization of OVB1 and OKM1 (anti-C3bi receptor) antibodies to specific granules of PMNs. Localization of OVB1 and OKM1 antibodies to granular structures in the PMN was confirmed by electron microscopy using the ferritin bridge technique. The antigen reacting with the OVB1 antibody was shown to be neuraminidase sensitive, but protease insensitive. The OVB1 monoclonal antibody may be useful in identification of ovarian tumors and subclassification of myeloid leukemias.
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PMID:Characterization of a monoclonal antibody, OVB1, which binds to a unique determinant in human ovarian carcinomas and myeloid cells. 246 82


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