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Biomedical subjects

M J Imber

Publications and source records attributed to M J Imber.

At least 19 recordsLinked to original sources
PubMed1990

Yellow nail syndrome.

The yellow nail syndrome is characterized by yellow, slow-growing nails in association with lymphedema, idiopathic pleural effusions, chronic bronchiectasis, and chronic sinusitis. We report two patients with yellow nail syndrome in whom spontaneous clearing of the nail changes occurred without resolution of the respiratory involvement. This observation suggests that nail changes may not result from the systemic manifestations. We also report for the first time the histopathologic findings of the nail matrix and bed, which demonstrate dense, fibrous tissue replacing subungual stroma with numerous ectatic, endothelium-lined vessels that are similar to that in the pleura in yellow nail syndrome. We hypothesize that primary stromal sclerosis may lead to lymphatic obstruction, thus explaining the clinical manifestations.

Chronic Disease↗
PubMed1990

Benign cutaneous lesions potentially misdiagnosed as malignant neoplasms.

Presented are five benign skin lesions that have features simulating malignant skin lesions. Although not a comprehensive review of all such potentially troublesome lesions, those reviewed here include (1) keratoacanthoma, (2) desmoplastic trichoepithelioma, (3) sclerosing hemangioma, (4) phototoxic drug eruption, and (5) pigmented spindle cell nevus. Those features, allowing their separation from malignant lesions, are presented.

Diagnosis, Differential↗
PubMed1989

Granulomatous eruption after BCG vaccine immunotherapy for malignant melanoma.

In a patient receiving intralesional bacille Calmette-Guérin vaccine injections for recurrent cutaneous metastases of malignant melanoma of the right leg, a striking eruption developed on that limb only. The eruption consisted of multiple 1 to 2 mm, reddish brown, flat-topped papules, with confluence into plaques. Histopathologic examination showed multiple tuberculoid granulomas within the papillary and reticular dermis; special stains and cultures were negative for mycobacteria.

BCG Vaccine↗
PubMed1987

Iron overload and mobilization in long-term hemodialysis patients.

Iron overload from repeated transfusions of RBCs in long-term hemodialysis patients is a problem of increasing clinical significance. We report on the prevalence of and diagnostic criteria for identification of hemodialysis patients with iron overload. In 150 unselected hemodialysis patients, 62 (41%) had ferritin levels greater than 2,000 ng/mL (normal = 10 to 360 ng/mL). In 16 of these patients, accurate transfusion histories were obtained and ferritin levels correlated with calculated transfusional iron burden (r = 0.553, P less than .05). These patients could be divided into two distinct groups on the basis of their response to a single dose (2 g, IV) of deferoxamine: "high" responders had twice the level of feroxamine (the chelated product of deferoxamine and iron) of the "low" responders (P less than .001). High responders also had significantly higher prevalence of the "hemochromatosis" alleles A3, B7, and B14 than a large group of dialysis patients awaiting transplantation (71% v 37%, P less than .001). In two patients with iron overload and clinically significant bone disease, bone histology revealed prominent iron staining at the calcification front. We conclude that transfusional iron overload is a significant clinical problem in long-term hemodialysis patients, that may also be associated with bone pathology.

Adult↗
PubMed1986

The binding of fucose-containing glycoproteins by hepatic lectins. Re-examination of the clearance from blood and the binding to membrane receptors and pure lectins.

The nature of the hepatic receptors that bind glycoproteins through fucose at the non-reducing termini of oligosaccharides in glycoproteins has been examined by three different approaches. First, the clearance from blood of intravenously injected glycoproteins was examined in mice with the aid of neoglycoproteins of bovine serum albumin (BSA). The clearance of fucosyl-BSA was rapid and was not strongly inhibited by glycoproteins that inhibit clearance mediated by the galactose or the mannose/N-acetylglucosamine receptors of liver. The clearance of Fuc alpha 1,3(Gal beta 1,4)GlcNAc-BSA (where Fuc is fucose) was inhibited weakly by either Fuc-BSA or Gal beta 1,4GlcNAc-BSA but strongly by a mixture of the two neoglycoproteins, suggesting that its clearance was mediated by hepatic galactose receptors as well as by a fucose-binding receptor. Second, the binding of neoglycoproteins to a membrane fraction of mouse liver was examined. Fuc-BSA binding to membranes was Ca2+ dependent but was not inhibited by glycoproteins that would inhibit the galactose or the mannose/N-acetylglucosamine receptors. In addition, the binding of Fuc-BSA and Gal beta 1,4GlcNAc-BSA differed as a function of pH, in accord with binding of Fuc-BSA through fucose-specific hepatic receptors. Finally, the binding of neoglycoproteins to the pure galactose lectin from rat liver was examined. Neither Fuc-BSA nor Fuc alpha 1,2Gal beta 1,4GlcNAc-BSA bound the galactose lectin, although Fuc alpha 1,3(Gal beta-1,4) GlcNAc-BSA bound avidly. Taken together, these studies suggest that a fucose-binding receptor that differs from the galactose and the mannose/N-acetylglucosamine receptors may exist in rat and mouse liver.

Animals↗
PubMed1983

Clearance and binding of native and defucosylated lactoferrin.

These studies explore the role of carbohydrate recognition systems and the direct involvement of terminal alpha 1-3-linked fucose in the clearance of lactoferrin from the murine circulation and in the specific binding of lactoferrin to receptors on murine peritoneal macrophages. As previously reported, radiolabelled lactoferrin cleared very rapidly (t1/2 less than 1 min) after intravenous injection into mice. However, competing levels of ligands specific for the hepatic galactose receptor (asialo-orosomucoid), the hepatic fucose receptor (fucosyl-bovine serum albumin), and the mononuclear-phagocyte system pathway recognizing mannose, N-acetylglucosamine and fucose (mannosyl-, N-acetylglucosaminyl- and fucosyl-bovine serum albumin) did not block radiolabelled lactoferrin clearance in vivo or binding to mouse peritoneal macrophage monolayers in vitro. Almond emulsin alpha 1-3-fucosidase was used to prepare defucosylated lactoferrin in which 88% of the alpha 1-3-linked fucose was hydrolysed. No difference in clearance or receptor binding was observed between radiolabelled native and defucosylated lactoferrin. Fucoidin, a fucose-rich algal polysaccharide, completely inhibits the clearance in vivo and macrophage binding in vitro of lactoferrin. This effect, however, is probably not the result of competition for binding to the fucose receptor, since gel-filtration studies demonstrated formation of a stable complex between lactoferrin and fucoidin. The present results indicate that the lactoferrin-clearance pathway is distinct from several pathways mediating glycoprotein clearance through recognition of terminal galactose, fucose, N-acetylglucosamine or mannose. Furthermore, alpha 1-3-linked fucose on lactoferrin is not essential for lactoferrin clearance in vivo or specific binding to macrophage receptors in vitro.

Animals↗
PubMed1982

Receptors for maleylated proteins regulate secretion of neutral proteases by murine macrophages.

Receptors for maleylated or acetylated proteins as well as for alpha-2-macroglobulin-protease complexes on macrophages serve as scavengers by mediating the uptake of macromolecules from the extracellular compartment. Described in this report is a novel function of these receptors on macrophages: regulation of neutral protease secretion. The binding of maleylated bovine serum albumin to macrophages triggered secretion of three neutral proteases: neutral caseinases, plasminogen activator, and cytolytic proteinase. Release of acid phosphatase, however, was not induced. An important biological consequence of protease secretion by macrophages, tumor-cytolysis, was also triggered by engagement of the receptor for maleylated bovine serum albumin. By contrast, the binding of alpha-2-macroglobulin-protease complexes to the macrophages suppressed secretion of all three proteases. Thus two receptors heretofore believed to serve principally as scavengers also regulate secretory functions of macrophages.

Animals↗
PubMed1982

Purification of an almond emulsin fucosidase on Cibacron blue-sepharose and demonstration of its activity toward fucose-containing glycoproteins.

The almond emulsin fucosidase that specifically hydrolyzes fucose in alpha (1-3) linkage to N-acetylglucosamine has been purified 1250-fold. The purification procedure includes ion exchange chromatography on sulfopropyl-Sephadex C-25, gel filtration on Sephacryl S-200, and affinity chromatography on Cibacron blue-Sepharose 4B-CL. The molecular weight of the fucosidase was estimated by gel filtration as approximately 73,000. Enzyme activity was maximal at pH 5.3 in acetate buffer and was dependent on ionic strength; at least 0.1 M NaCl was necessary for optimal activity. The purified enzyme was free of beta-galactosidase activity toward the glycoprotein substrate [3H]galactosyl-asialotransferrin and did not release fucose from substrates containing fucose in alpha (1-6) linkage, (bovine IgG glycopeptides) or in alpha (1-2) linkage, (2'-fucosyllactose). The fucosidase displayed activity toward two glycoprotein substrates known to contain fucose in alpha (1-3) linkage. Extensive incubations resulted in the release of 83% and 43% of the total fucose of asialoorosomucoid and lactoferrin, respectively. The fucosidase did not release fucose from either the "slow" or the "fast" form of alpha 2-macroglobulin, suggesting the absence of fucosyl alpha (1-3) linkages on that glycoprotein.

Glycopeptides↗
PubMed1981

Clearance and binding of two electrophoretic "fast" forms of human alpha 2-macroglobulin.

These studies explore the role of conformational change and exposed carbohydrate residues in the clearance of alpha 2-macroglobulin-trypsin (alpha 2M-T) complexes in the mouse. Human alpha 2-macroglobulin (alpha 2M) was purified and demonstrated to be homogeneous in the electrophoretic "slow" form. Two conformationally altered derivatives, alpha 2M-T and alpha 2-macroglobulin-methylamine (alpha 2M-MeNH2), were prepared and demonstrated to exist in the electrophoretic "fast" form. Radiolabeled alpha 2M-T and alpha 2M-MeNH2 were cleared rapidly with a half-life of 2-4 min following injection into mice. Radiolabeled native alpha 2M, however, remained in the circulation with a half-life of several hours. Both alpha 2M-T and alpha 2M-MeNH2 bound specifically to mouse peritoneal macrophages at 4 degrees C and occupancy of receptor sites increased with increasing time and radioligand concentration. Excess amounts of unlabeled alpha 2M-T or alpha 2M-MeNH2 cross-completed with trace amounts of the other in both clearance studies and binding assays, indicating that both derivatives were removed by the same receptor pathway. The clearance and binding of alpha 2M-T and alpha 2M-MeNH2 were not inhibited by excess amounts of unlabeled asialoorosomucoid, fucosyl-bovine serum albumin, mannosyl-BSA, or N-acetylglucosaminyl-BSA. Our results indicate that the clearance pathway removing alpha 2M-T complexes from the circulation recognizes a fundamental conformational change in alpha 2M secondary to protease binding, which can also be induced by exposure to methylamine. Therefore, other chemical or physical alterations that occur in alpha 2M upon binding trypsin, apart from the conformational change also present in alpha 2M-MeNH2, do not seem necessary for the recognition of alpha 2M-T by cells in the clearance pathway. In addition, this pathway appears distinct from several systems already described mediating clearance of glycoproteins through recognition of terminal galactose, fucose, N-acetylglucosamine, or mannose on oligosaccharide side chains.

Animals↗