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Biomedical subjects

A F Michael

Publications and source records attributed to A F Michael.

At least 73 records · Page 4Linked to original sources
PubMed1986

Differential localization of ferritin and ferritin immune complexes in the spleen: influence of the charge of ferritin.

Prior studies have demonstrated that following administration to animals most antigens (Ag) localize within the red pulp whereas immune complexes (IC) are found in the white pulp. Using ferritin and ferritin IC, we describe a striking different localization of the Ag alone compared with the same AG complexed with its antibody. In addition, cationization of native ferritin (pI 4.5) to cationized ferritin (pI 7) decreases significantly the splenic uptake of the Ag but has no effect on the uptake of the respective ferritin IC by the white pulp.

Animals↗
PubMed1986

Immunochemistry of urinary calcium oxalate crystal growth inhibitor (CGI).

Calcium oxalate crystal growth inhibitor (CGI) was isolated from human urine in monomeric form (14,000 daltons). Antibody was elicited and purified to monospecificity by affinity chromatography. Tamm-Horsfall protein was isolated from human urine and an antibody to Tamm-Horsfall protein compared to anti-CGI. The anti-CGI reacted with its antigen on immunodiffusion, by ELISA and by Western Blotting of polyacrylamide gel electrophoresis-separated antigen. Immunofluorescent localization of CGI was found in distal renal tubules. This was precisely the localization of Tamm-Horsfall protein. Isolated Tamm-Horsfall protein was found to bind CGI which could only be partially removed with EDTA. While anti-CGI is suitable to assay CGI in human urine by ELISA techniques, it will also detect CGI that is complexed to THP. While the CGI found in human urine possesses 90% of the urinary macromolecular crystal growth inhibitor activity, THP is without effect on crystal growth, in spite of bound CGI. The balance between free CGI and that bound to Tamm-Horsfall protein may be important in the overall balance of urinary macromolecules that affect calcium oxalate nephrolithiasis.

Calcium Oxalate↗
PubMed1986

Nephritogenic antigen determinants in epidermal and renal basement membranes of kindreds with Alport-type familial nephritis.

We probed epidermal basement membranes (EBM) of acid-urea denatured skin from members of kindreds with Alport-type familial nephritis (FN) for the presence of antigens reactive with Goodpasture sera (GPS) and serum (FNS) from an Alport patient who developed anti-glomerular basement membrane (GBM) nephritis in a renal allograft. By immunoblotting, GPS reacted primarily with the 28,000 molecular weight (mol wt) monomer but also the 24,000 mol wt and 26,000 mol wt monomers of the noncollagenous globular domain (NC1) of type IV collagen from normal human GBM, while FNS identified only the 26,000-mol wt monomer. FNS reacted with EBM of 12 controls and nine unaffected male kindred members but not EBM of eight affected males. Five affected females exhibited interrupted reactivity of FNS with EBM. GPS showed variable reactivity with EBM and was not discriminating with respect to Alport-type FN. FNS did not stain renal basement members of five affected males. However, the EBM, tubular basement membrane, and Bowman's capsules of affected males contained antigens reactive with GPS. These immunochemical studies suggest that the FNS antigen is distinct from Goodpasture antigen(s). The expression of FNS antigen located on the NC1 domain of type IV collagen is altered in basement membranes of patients with Alport-type FN, and the distribution of this antigenic anomaly within kindreds suggests X-linked dominant transmission of a defective gene.

Basement Membrane↗
PubMed1986

Identification of lymphohemopoietic cells in the kidneys of normal rats.

Recently developed monoclonal antibodies against rat lymphohematopoietic cells provide ideal probes for study of the role of the cellular immune system in experimental renal disease. Techniques for optimal and reliable labeling of cells present within the glomeruli have not yet been established. In this study it is shown that a small number of lymphoid and mononuclear cells can be identified within normal rat glomeruli present on frozen kidney sections (4 mu) when indirectly stained with monoclonal antibody W3/13, W3/25, OX1, OX3, or OX8 with the use of sequential incubations with F(ab')2 fragments of 2 fluorochrome-labeled antibodies, the nuclear stain ethidium bromide, and p-phenylenediamine added to retard fluorescence quenching. Cell counts showed good correlation with those obtained with the use of intact glomeruli isolated simultaneously from the same kidneys (r = 0.95 for saline-perfused kidneys; r = 0.99 for exsanguinated kidneys). Studies using isolated glomeruli pretreated with trypsin and DNAase failed to provide any advantage, because the enzymes did not enhance cellular reactivity with W3/13, OX8, or OX3, whereas the W3/25-reactive epitope was completely destroyed. It was only the OX1-reactive epitope which was enhanced by enzyme pretreatment. Thus, the described technique can accurately quantitate glomerular lymphohemopoietic cells on sections of frozen kidney and should provide a reliable method for the study of renal disease.

Animals↗
PubMed1986

Amyloid P component is not present in the glomerular basement membrane in Alport-type hereditary nephritis.

Serum amyloid P component (SAP) is a normal plasma glycoprotein immunochemically indistinguishable from amyloid P, a glycoprotein found in all tissue amyloid deposits. SAP has also been shown to be a constituent of normal glomerular basement membrane (GBM). In this study the authors discovered a unique association between SAP and Goodpasture (GP) antigen. In those patients whose GBM lack GP antigen (those with Alport-type hereditary nephritis) SAP is also uniformly absent. Although the relationship between these two components is unknown, this association may provide clues to the abnormality of GBM in Alport-type hereditary nephritis.

Anti-Glomerular Basement Membrane Disease↗
PubMed1985

Urinary albumin excretion in renal transplant donors.

Twenty-four hour urinary albumin excretion was measured using sensitive methods in 129 renal transplant donors 1 to 22 years (mean 7.3 years) after kidney donation. The 24 hour urinary albumin excretion values for the donor group was 6 +/- 9.9 mg (mean +/- standard deviation) (range of 0.1 to 65.2 mg) and was 7.7 +/- 4.5 mg for the control group. Five donors (3.9 percent) had 24 hour urinary albumin excretion levels of 25.5 to 65.2 mg 6 to 13 years after donation, values that were greater than a single value from any member of the control group. Elevated diastolic blood pressure (90 mm Hg or greater) was present in these five donors, and in three, labile or established hypertension was present at the time of donation. It is likely that more careful screening of potential donors with labile or fixed hypertension would further reduce the incidence of microalbuminuria in the renal transplant donor. We conclude that urinary albumin excretion values are within the normal range in most renal transplant donors studied several years after renal donation.

Adolescent↗
PubMed1985

Interstitial nephritis associated with cytomegalovirus infection.

Cytomegalovirus (CMV) infection may cause impairment of renal graft function and glomerular and interstitial injury. Whether renal lesions are the consequence of infection or of decreased graft tolerance is uncertain. We studied autogenous renal tissues obtained from two infants with CMV infection. Light and electron microscopy revealed interstitial nephritis, but not glomerulopathy. Analysis of frozen tissues using monoclonal antibodies by indirect immunofluorescence demonstrated that most infiltrating cells were T cells (OKT3+), the majority of which reacted with OKT8. In contrast, tissues obtained from one individual prior to CMV infection, from individuals with end-stage kidney disease, and from normal renal donors revealed either balanced proportions of OKT4+ and OKT8+ cells or a preponderance of the former. Thus, CMV infection may be associated with interstitial nephritis involving a characteristic subpopulation of T cells.

Antibodies, Monoclonal↗
PubMed1985

Detection of hidden nephritogenic antigen determinants in human renal and nonrenal basement membranes.

The reactivity of 10 human anti-glomerular basement membrane (GBM) autoantibodies with basement membrane antigens of human adult and infant kidney, lung, placenta, and skin was examined by ELISA and immunofluorescence microscopy. All autoantibodies were previously shown to react with adult kidney by indirect immunofluorescence and with collagenase-digested adult GBM by ELISA. Four antibodies (group A) were positive on infant and fetal kidney sections by immunofluorescence, and six antibodies were negative (group B). By ELISA both groups of antibodies were reactive with collagenase digests of infant GBM. After denaturation with 6M urea (pH 3.5) infant and fetal kidney sections reacted with group B autoantibodies by immunofluorescence, which indicated that the antigen(s) was masked. Hidden antigenic determinants in lung, placenta, and skin were reactive with groups A and B autoantibodies only after acid urea denaturation of tissue sections. Within each group variability in reactivity of autoantibodies with basement membranes suggested further heterogeneity.

Adult↗
PubMed1985

Enzyme immunoassay of anti-glomerular basement membrane antibodies.

An immunoassay has been developed to detect anti-glomerular basement membrane (GBM) antibodies in human sera. Various plating conditions, types of microtiter plates, and the use of biotinylated or peroxidase-labeled secondary antibodies were examined. The described assay is reliable, fast, and convenient. Sera with positive reactivity in anti-GBM nephritis and Goodpasture's syndrome are readily discriminated from sera obtained from normal individuals or patients with a variety of other diseases.

Anti-Glomerular Basement Membrane Disease↗
PubMed1985

Membrane attack complex of complement in dermatitis herpetiformis.

The assembly of membrane attack complex (MAC) of complement implies activation of complement to the attachment of C9 and the presence of MAC on tissue suggests a possible pathogenic role for complement in disease since MAC is able to damage membranes. We examined normal skin of five patients with dermatitis herpetiformis for the presence of MAC using a monoclonal antibody (poly C9-MA) that recognizes a neoantigen of C9 that is not present on monomeric C9 but is common to both isolated MAC and to polymerized C9. Granular deposits of polymerized C9 were found at the sites of IgA deposition in the dermal papillae of normal skin from all patients. The pathologic importance of this finding is uncertain.

Antibodies, Monoclonal↗
PubMed1985

Recurrent diabetes mellitus in the pancreas iso- and allograft. A light and electron microscopic and immunohistochemical analysis of four cases.

Four patients with type 1 diabetes mellitus received segmental pancreatic grafts. The donors were HLA-identical twins in three patients and an HLA-identical sibling in one. Each patient had normal glucose metabolism in the posttransplantation period but impaired graft function developed after 6 to 12 weeks. Complete loss of function developed in three patients. The fourth patient received immunosuppressive therapy but continues to require a low dose of insulin 15 months following transplantation. Pancreatic graft biopsy at the time of declining graft function in three patients revealed a mononuclear cell infiltrate centered upon islets consisting of variable numbers of T11 (pan T), OKT8 (suppressor-killer), OKT9 (transferrin receptor), OKT10 (activated), and HLA-DR-reactive mononuclear cells, as well as 63D3 and OKM1 reactive monocytes. Biopsies obtained following loss of graft function revealed resolution of the inflammatory process and selective destruction of all islet beta-cells in two patients, whereas graft biopsy in one patient demonstrated a mononuclear cell infiltrate in islets containing demonstrable beta-cells but no infiltrate in islets without beta-cells. Following immunosuppressive therapy the fourth patient showed resolution of the insulitis and destruction of beta-cells in 70% of the islets. The variable numbers of beta-cells observed in the remaining islets likely account for the relatively low amount of exogenous insulin required by this patient. There was no immunohistologic evidence of humoral mediated immune reaction in any of the biopsies. It is postulated that selective beta-cell destruction was a consequence of cell-mediated immunity leading to recurrent diabetes mellitus.

Adult↗
PubMed1984

Albumin deposition in dermal capillary basement membrane in parents of type 1 (insulin-dependent) diabetic patients.

Skin biopsies were performed to examine dermal capillary basement membranes for albumin by immunofluorescence microscopy in children and young adults with Type 1 (insulin-dependent) diabetes from simplex and multiplex families, their non-diabetic parents and control subjects. Circumferential vessel staining for albumin was 12.0 +/- 14.4% (mean +/- SD) in diabetic patients from multiplex families, 18.8 +/- 20.0% in diabetic patients from simplex families, and 18.5 +/- 24.2% in unaffected parents from simplex families. These values were significantly higher (p less than 0.005) than those obtained in unaffected parents from multiplex families (0.4 +/- 0.9%) or control subjects (0.8 +/- 1.7%). There was no statistically significant difference between Type 1 diabetic probands from simplex or multiplex families and unaffected parents from simplex families. In the simplex families, positive capillary staining for albumin was present only in parents from families in which the diabetic proband had positive staining. In the parents, the presence of dermal capillary staining for albumin did not correlate with an abnormal glucose tolerance test or the presence of cytoplasmic islet cell antibodies. These observations suggest an abnormality in the dermal capillary basement membrane in some unaffected parents of Type 1 diabetic patients from simplex families.

Adolescent↗
PubMed1984

Kinetics of administered aggregated IgG in rats with passive Heymann's nephritis.

The kinetics of radiolabeled heat-aggregated human IgG (AHIgG125I) were studied in rats with passive Heymann's nephritis (PHN) induced 72 hr previously with decomplemented rabbit antiserum to rat FX1A. Control rats were injected with decomplemented normal rabbit serum (NRS). Following administration of AHIgG125I (40 mg per 100 g of body wt) control and FX1A animals were sacrificed in groups of five each at 2, 4, 8, 16, and 24 hr and kidney, liver, spleen, lung, plasma, and blood cells obtained. 131I-Labeled human serum albumin (HSA131I) was administered prior to sacrifice as a plasma marker. In FX1A rats the following observations were made in comparison with control rats: (1) A decrease in the concentration of AHIgG125I in glomeruli was observed at 2, 4, and 8 hr after administration; (2) a significant increase in clearance reflected by a decrease in the concentration of plasma trichloroacetic acid (TCA)-precipitable radioactivity, and AHIgG125I (greater than 7 S) was present; (3) a significant increase in non-TCA-precipitable radioactivity in plasma and blood cells at most time periods; and (4) decreased concentrations of AHIgG125I in liver and spleen but not lung. The specificity of these observations was supported in separate experiments by the lack of any difference in the plasma levels of TCA-precipitable radioactivity after administration of radiolabeled albumin to FX1A and control rats. Studies in FX1A and control rats revealed no differences in body weight, kidney weight, hematocrit, blood volume, urine output, glomerular filtration rate, renal blood flow, or renal vascular resistance. A slight increase in urinary rat albumin excretion was observed in FX1A rats. The lower values of AHIgG125I observed in plasma, liver, and spleen associated with increased levels of non-TCA-precipitable radioactivity in plasma and blood cells suggest enhanced catabolism of AHIgG125I in FX1A rats, leading to decreased localization within the mesangium.

Animals↗
PubMed1984

The glomerular mesangium: kinetics using radiolabeled ferritin and the effects of aggregated IgG.

A quantitative method for studying glomerular mesangial kinetics using radiolabeled native ferritin (125I-NF) is described. Groups of Sprague-Dawley rats were given injections of monomeric 125I-NF in a dose of 10 mg/100 g and sacrificed at 4, 16, and 36 hr. Radioactivity was measured in preparations of isolated glomeruli, spleen, and liver, and in blood. After initial uptake, a progressive decrease in the concentration of 125I-NF was observed in the mesangium and other organs. To examine the effect of one macromolecule on the mesangial kinetics of NF a separate group of animals was given aggregated human IgG (AHIgG) (40 mg/100 g) 4 hr prior to administration of 125I-NF. The administration of AHIgG did not alter the kinetics of 125I-NF in the mesangium, plasma, or spleen but the disappearance of 125I-NF from the liver was accelerated. Although the cellular mechanisms for uptake of NF and AHIgG are different, the presence of one macromolecule (AHIgG) within the mesangium did not affect the uptake and disappearance of another (NF). Thus, the glomerular mesangium has a relatively high capacity under normal circumstances.

Animals↗