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)

Immunologic mechanisms of proteinuria were investigated in guinea pigs (GP) injected with sheep antiserum (NTS) to GP glomerular basement membrane (GBM). Linear deposition of sheep gamma 1 and gamma 2 IgG led to a prompt but transient (36 hr) increase in albumin excretion from control values of 0.026 +/- 0.013 mg/hr to maximal values of 26+/-12.1 mg/rh at six hours without detectable histologic or electron microscopic changes except for decreased staining for glomerular polyanion and epithelial cell foot process fusion. GBM permeability to anionic ferritin was not increased during proteinuria. Anti-GBM antibody deposits did not fix GP C3 or C4 in vivo or in vitro. NTS-induced proteinuria was the same in guinea pigs that were normal, greater than 95% depleted of C3 through C9, genetically deficient in C4, and depleted of circulating polymorphonuclear leukocytes (PMN). Prior administration of antihistamines, steroids, azathioprine, colchicine, indomethacin, heparin, aprotinin (Trasylol), and niridazole also failed to reduced proteinuria. Initial proteinuria subsided by 36 hr, did not recur despite linear deposition of GP gemma 1 and gemma 2 after day seven, and antibody to GMB-bound sheep globlin. In the GP nephrotoxic nephritis model, anti-GBM antibody deposits apparently mediate increased permeability to albumin by a currently undefined mechanism which is independent of complement, PMN, and other know mediators of inflammation.
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PMID:Complement-independent nephrotoxic nephritis in the guinea pig. 1 57

The formation of irreversible complexes between carrier ampholyte components and proteins was investigated by gel filtration of mixtures of proteins and radioactively labelled ampholytes. Experiments were performed both with purified proteins (albumin, ferritin, beta-glucuronidase) and with a complex mixture of proteins (serum); in no case was binding of ampholytes to proteins detected. Thus the results argue against the occurrence in isoelectric focusing of proteins of artifacts due to such complex formation.
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PMID:Evidence against the occurrence of artifacts due to carrier ampholyte-protein binding during isoelectric focusing. 23 9

Nephrotoxic nephritis was induced in Sprague-Dawley and Munich-Wistar rats by the injection of rabbit antirat kidney serum. A biphasic pattern of proteinuria was induced: the heterologous phase with a peak of proteinuria occurring at 10 to 16 hours, and the autologous phase with a peak at 10 to 15 days. For morphologic studies, glomeruli were fixed by perfusion, or by drip-fixation during good blood flow. In the heterologous phase, glomerular endothelial detachment or loss and leukocytic infiltration were prominent. In the autologous phase, focal detachment of glomerular endothelium and epithelium was commonly found. At sites of endothelial loss, in both phases, endogenous albumin (demonstrated by an ultrastructural immunoperoxidase technique), but not intravenously injected ferritin, showed abnormally deep penetration into the glomerular basement membrane. At sites of epithelial loss, found in the autologous phase, both albumin and ferritin were detected throughout the glomerular basement membrane. It is proposed that, in glomerular disease, leakage of plasma proteins may occur across the glomerular basement membrane at sites of endothelial or epithelial detachment.
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PMID:An ultrastructural study of the mechanisms of proteinuria in rat nephrotoxic nephritis. 32 69

Kinetic studies on the uptake and elimination of ferritin and ferritin-protein conjugates in the rat glomerular mesangium are reported. Ferritin was prepared from horse spleens and conjugates were prepared using either human IgG or albumin. The degree of mesangial uptake was dose dependent and a competitive effect with the reticuloendothelial system was observed. Maximal mesangial fluorescence occurred at a lower dosage with conjugate than with native ferritin. In addition, conjugate persisted for months within the mesangium as compared to a matter of days in the case of ferritin alone. The disappearance of native ferritin from the mesangium paralleled that seen in the circulation. Conjugate, however, disappeared far more rapidly from the circulation than from the mesangium. At a point in time when the mesangium still contained conjugate but the blood was negative, rabbit antiserum to ferritin was injected and was observed to deposit in the mesangium. This demonstrated the accessibility of mesangially sequestered antigen to circulating antibody. This system provides a model for long term studies on the effect of immune reactions occurring in the mesangium.
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PMID:Comparison of the handling of ferritin and ferritin-protein conjugates by the glomerular mesangium: kinetic studies in the rat. 36 34

Measurements of filtration coefficients (Lp) and osmotic reflexion coefficients (sigma) of single capillaries in the frog mesentery suggest that fluid flows through the walls of these vessels in two types of channel. One channel type (representing about 10% of Lp) appears to be exclusively available for water whereas the other channels appear available for both water and hydrophilic solutes though they severely restrict the passage of albumin (sigma = 0.81). The effects of proteins in the perfusate upon Lp and studies on the passage of ferritin into the surface vesicles of the endothelial cells, suggest that an important component of capillary permeability may reside in an endocapillary layer.
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PMID:The investigation of capillary permeability in single vessels. 38 45

Syncytiotrophoblast microvillous plasma membrane (StMPM) preparations were obtained from human full-term placentae by previously published methods of cold saline extraction and phase centrifugation. Purity of these preparations was assessed by electron microscopy, enzyme analysis and hydroxyproline content. IgG, albumin, alkaline phosphatase, transferrin, ferritin and alpha 2-macroglobulin were consistently detected in the aqueous soluble fraction from sodium deoxycholate-solubilised StMPM preparations by antigenic or electrophoretic analysis, beta 2-Microglobulin was not detected in these preparations. Up to 21 discrete protein bands could be demonstrated by SDS--PAGE, and their molecular weights determined. Many of these components need to be further identified, including a glycoprotein of molecular weight 36 500 which was particularly prominent. The soluble fraction from StMPM preparations gave a single strong precipitin reaction in immunodiffusion against wheat germ agglutinin, but not against other lectins studied.
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PMID:Characterisation of the soluble fraction of human syncytiotrophoblast microvillous plasma membrane-associated proteins. 55 Nov 70

A series of specific macromolecules (tetanus toxin, cholera toxin, nerve growth factor [NGF], and several lectins) have been shown to be transported retrogradely with high selectivity from terminals to cell bodies in various types of neurons. Under identical experimental conditions (low protein concentrations injected), most other macromolecules, e.g. horseradish peroxidase (HRP), albumin, ferritin, are not transported in detectable amounts. In the present EM study, we demonstrate selective binding of tetanus toxin to the surface membrane of nerve terminals, followed by uptake and subsequent retorgrade axonal transport. Tetanus toxin or albumin was adsorbed to colloidal gold particles (diam 200 A). The complex was shown to be stable and well suited as an EM tracer. 1-4 h after injection into the anterior eye chamber of adult rats, tetanus toxin-gold particles were found to be selectively associated with membranes of nerve terminals and preterminal axons. Inside terminals and axons, the tracer was localized mainly in smooth endoplasmic reticulum (SER)-like membrane compartments. In contrast, association of albumin-gold complexes with nervous structures was never observed, in spite of extensive uptake into fibroblasts. Electron microscope and biochemical experiments showed selective retrograde transport of tetanus toxin-gold complexes to the superior cervical ganglion. Specific binding to membrane components at nerve terminals and subsequent internalization and retrograde transport may represent an important pathway for macromolecules carrying information from target organs to the perikarya of their innervating neurons.
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PMID:Selective binding, uptake, and retrograde transport of tetanus toxin by nerve terminals in the rat iris. An electron microscope study using colloidal gold as a tracer. 65 8

Although large hemoglobin inclusions are observed in intraerythrocytic Babesia microti parasites, they are absent from parasites freed of hamster red cells by immune lysis with anti-hamster erythrocyte serum. Babesia microti has no cytostome. This parasite, therefore, does not appear to feed by phagocytosis of large boluses of hemoglobin, as does Plasmodium. To determine whether Babesia can pinocytose protein, free parasites were fed ferritin in an in vitro system. Ferritin was taken up from the entire cell surface into narrow channels within 15 min at 37 C. Only merozoites, with their pellicular complex, failed to take up the protein. By 60 min, the ferritin was highly concentrated in many channels and vesicles, which formed interconnecting stacks. The ferritin-containing channels became associated with membrane whorls of the multimembranous structure. Membrane whorls were also observed in the process of extrusion in samples incubated for longer times. These events may represent steps in the digestion and excretion of the pinocytosed protein. Empty channels formed when Babesia was fed albumin. The diaminobenzidine reaction for hemoprotein was positive for the channels in both free and intraerythrocytic babesias. The staining reaction was completely inhibited by cyanide, but not at all by aminotriazole. These results further suggest that Babesia pinocytoses hemoglobin in vivo. Plasmodium lophurae parasites freed of red cells by immune lysis are surrounded by 2 membranes and apparently can ingest ferritin only through the cytostome. Extracellular cytostomal feeding involves both membranes, as it does in vivo. Ferritin was found in food vacuoles, some of which contained hemoglobin ingested before parasite isolation, connected to or near the cytostome. In both Plasmodium and Babesia low temperature inhibited ferritin uptake.
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PMID:Feeding mechanisms in extracellular Babesia microti and Plasmodium lophurae. 93 77

Infusion of rats with [U-14C]glycine resulted in labelling of glycine and serine in plasma albumin and liver ferritin. The patterms of labelling in these two proteins were not similar, suggesting that each is synthesized from a different pool of free amino acids.
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PMID:Compartmentation of albumin and ferritin synthesis in rat liver in vivo. 94

Humoral immune processes mediate alterations in glomerular basement membrane (GBM) permeability by two mechanisms. One requires complement and polymorphonuclear leukocytes and the second is complement- and polymorphonuclear leukocyte-independent. The structural basis for enhanced GBM permeability induced by anti-GBM antibody is not clear. Experimental anti-GBM glomerulopathy was induced in guinea pigs by immunization with human GBM in complete Freund's adjuvant. Control animals received injections of complete Freund's adjuvant alone. Light, immunofluorescent, and electron microscopic studies were done on eight heavily proteinuric animals, four immunized nonproteinuric animals, three controls, and two normal animals. All animals that received injections of GBM had intense linear deposits of gamma2 anti-GBM antibody. Complement deposition was not demonstrable in vivo, and anti-GBM antibody deposits did not fix complement in vitro. Histologic abnormalities in proteinuric animals were confined to the GBM, which was of variable density and had a characteristic beaded thickening, with numerous areas of electron lucency most prominent in the outer aspect of GBM in peripheral portions of capillary loops. The inner margin and endothelium were normal. Ultrastructural tracer studies with ferritin demonstrated increased permeability confined to portions of GBM demonstrating ultrastructural lesions. The urine protein excreted by animals with ultrastructural GBM lesions was largely albumin. The absence of complement deposition accompanying anti-GBM antibody deposits in vivo and the unique GBM lesion in this model differ from the findings in nephritis induced by most heterologous nephrotoxic antibodies and suggest that GBM injury in this model is mediated by autologous antibody through complement-independent mechanisms. The selective proteinuria and ultrastructural lesions suggest a derangement in glomerular permeability functionally localized to the epithelial side of the GBM and could reflect an antibody-mediated abnormality in GBM biosynthesis.
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PMID:Experimental glomerulonephritis in the guinea pig. II. Ultrastructural lesions of the basement membrane associated with proteinuria. 108 38


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