Biomedical subjects

M R Daha

Publications and source records attributed to M R Daha.

490 records · Page 28Linked to original sources

PubMedDate not supplied

Characterization of anti-endothelial antibodies in patients with rheumatoid arthritis complicated by vasculitis.

Anti-endothelial antibodies (AEA) have been described in patients with rheumatoid arthritis (RA) complicated by vasculitis. In this study we made use of an ELISA and immunoblot technique (IBT) to further characterize AEA of the IgG class in serum of patients with rheumatoid vasculitis (RV) and to investigate the relationship between the presence of IgG-AEA and vasculitis. IgG-AEA as measured by ELISA or IBT could be detected in the serum from 20 of the 23 (87%) RV patients, in 2 out of 13 (15%) patients with RA and in one of 15 healthy donors. The IBT revealed reactivity of IgG-AEA against a total of 12 bands of endothelial antigens ranging in size from 16 to 68 kD. IgG-AEA as measured by ELISA and IBT in serum samples of patients followed longitudinally were present more frequently and in higher titres in patients with active RV as compared to patients with vasculitis in remission. A significant correlation was found between the presence of clinical signs of vasculitis and serum IgG-AEA reactivity against an endothelial membrane antigen of 44 kD. These data show that the pattern of IgG-AEA reactivity in the serum of RV patients is heterogeneous and suggest that IgG-AEA against one particular antigen is involved in the pathogenesis of RV.

Antibodies↗

PubMedDate not supplied

Biocompatibility and performance of a modified cellulosic and a synthetic high flux dialyzer. A randomized crossover comparison between cellulose triacetate and polysulphon.

The biocompatibility and performance of two high flux membranes (modified cellulosic: cellulose-triacetate (CTA), and a synthetic material: polysulphon [PS]) were assessed in 31 stable patients on hemodialysis (HD) in a randomized crossover study. Parameters evaluated included leukocytes, complement activation products C3a and C5a, cytokines, lymphocyte subpopulations, urea, creatinine, phosphate, and beta 2 microglobulin. Considering biocompatibility, the drop in the number of leukocytes was more pronounced during CTA HD compared with PS (p = 0.045), although both were low in comparison with cuprammonium dialysis in the same patients, as observed during a separate study. Both membranes induced a low and transient state of complement activation. Interleukin 1 beta and interleukin 6 could not be detected at all, whereas tumor necrosis factor alpha levels were marginally elevated before and after HD with both membranes. During the first 30 min of HD with either membrane, the numbers of CD8+ cells decreased significantly, resulting in an increase in the CD4/CD8 ratios; in addition, the number of NK cells decreased. Performance, as measured by extraction ratios for small molecular weight solutes and Kt/V urea, was significantly better during CTA dialysis (p < 0.001), but almost similar after correction for membrane surface area. On the basis of these data, it seems justified to conclude that, whereas biocompatibility of the PS dialyzer appeared slightly superior to CTA, performance of both dialyzers was comparable.

Adult↗

PubMedDate not supplied

Autoantibodies to neutrophil cytoplasmic enzymes in Felty's syndrome.

In this study we determined the occurrence of anti-neutrophil cytoplasmic antibodies (ANCA) and the specificity of these antibodies (Ab) in the serum of patients with Felty's syndrome (FS) and in serum of patients with uncomplicated rheumatoid arthritis (RA). ANCA, detected by indirect immunofluorescence on ethanol-fixed neutrophils, was found in 77% of 30 patients with FS and in 36% of 50 RA patients. Ab against lactoferrin (LF) occurred more frequently in FS patients (50%) than in RA patients (4%), whereas reactivity against the other cytoplasmic antigens tested (proteinase-3, myeloperoxidase and elastase) did not differ significantly between these patient groups. The specific reactivity of FS sera with LF was established by demonstrating that the Ab reactivity resided in IgG, was located in the F(ab')2 fragments and could be inhibited from binding to the ELISA plate-bound LF by purified LF in the fluid phase. These results demonstrate that anti-LF Ab occur in FS and suggest that the detection of anti-LF Ab in patients with FS may be useful in the diagnosis of FS.

Adult↗

PubMedDate not supplied

Complement depletion abolishes IgA-mediated glomerular inflammation in rats.

Recently, we developed an acute model for IgA-mediated glomerular inflammation in rats in which it was shown that polymeric (p) but not monomeric (m) IgA-containing immune complexes induce acute glomerular inflammation. The glomerular IgA-mediated inflammation is characterized by the activation of complement (C), the presence of intraglomerular macrophages and proteinuria. In the present study, we investigated the role of C in this IgA-mediated nephritis. Rats were pretreated either with cobra venom factor (CVF) to deplete them of circulating C3 or with phosphate-buffered saline followed by introduction of mesangial IgA deposits. Upon deposition of pIgA in the mesangial area, acute proteinuria was observed only in normocomplementemic rats and not in C-depleted animals. Immunofluorescent analysis revealed deposition of C3 and C9 in a pattern identical to that of IgA in the glomeruli of normal rats. Rats pretreated with CVF displayed clear mesangial deposition of IgA in the absence of C3 and C9. In none of the two groups were C4 deposits seen, indicating activation of C via the alternative pathway. In normocomplementemic animals, deposition of IgA together with C3 was associated with an influx of macrophages at day 2. C-depleted rats receiving pIgA also showed an influx of macrophages at 24 h following CVF administration and 1 and 2 days after IgA injection. However, no proteinuria was seen. To obtain insight into the mechanism of macrophage influx in the CVF-treated rats, we also analyzed the number of intraglomerular macrophages in rats receiving only CVF, without introduction of mesangial IgA deposits.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗