Biomedical subjects

S Uwatoko

Publications and source records attributed to S Uwatoko.

At least 37 records · Page 2Linked to original sources

PubMed1993

Shunt nephritis: efficacy of an antibiotic trial for clinical diagnosis.

Coagulase negative staphylococcus, a normal skin flora, is especially nosopoietic under shunt management, because coagulase negative staphylococcus sometimes forms a biofilm around itself at catheter tips in vivo, which shields the organism from the effects of antibiotics. But it is difficult to distinguish this pathogen from a possible confounding contamination of a blood culture. In this article, we report a case, and discuss how a patient with suspected shunt nephritis should be examined and treated. In addition, to further histological and prognostic interpretation, we review the previously reported cases of shunt nephritis in Japanese adults.

Adult↗

PubMed1992

Antibodies against sulphatide in sera from patients with autoimmune rheumatic diseases.

We tested sera of patients with various autoimmune rheumatic diseases for the presence of antibodies against sulphatide (an acidic glycosphingolipid), identified as a target antigen for antibodies against the liver cell membrane. Thirty-five percent (7/20) of patients with lupus in the active stage possessed anti-sulphatide antibodies, whereas 10% (2/20) of those in the inactive stage and 20% (4/20) of those in the stationary stage possessed such antibodies. Moreover, 10% (3/29) of patients with other autoimmune rheumatic diseases also possessed anti-sulphatide antibodies. The level of anti-sulphatide antibodies was significantly correlated with the levels of anti-double-stranded (ds) DNA antibodies (r = 0.634, P less than 0.001) and dextran sulphate-binding IgG (r = 0.407, P less than 0.001). The serum levels of antibodies against sulphatide were correlated with a history of seizures or psychosis in patients with autoimmune rheumatic diseases. Gels coupled with polyanionic dextran sulphate, monoanionic sulphanilic acid and DNA were shown effectively to adsorb anti-sulphatide antibodies in the sera of patients with active systemic lupus erythematosus (SLE) and autoimmune chronic active hepatitis (AI-CAH). These results suggest that the observed reactivity with sulphatide is due to the presence of antibodies capable of reacting with various anionic molecules in the sera of patients with autoimmune rheumatic diseases as well as those with AI-CAH.

Adsorption↗

PubMed1992

The B cell repertoire in patients with systemic autoimmune diseases: analysis of Epstein-Barr virus (EBV)-inducible circulating precursors that produce autoantibodies against nuclear ribonucleoprotein (nRNP).

Peripheral blood B cells from patients with systemic autoimmune disease and healthy volunteers were immortalized using EBV and the frequencies of B cell precursors that produced immunoglobulin class-specific antibodies against anti-nRNP, a specific marker for mixed connective tissue disease, were assessed using limiting dilution analysis. The frequencies of EBV-induced B cell precursors that produced IgG anti-nRNP were correlated closely with the serum titres of the corresponding autoantibodies, which indicates that B cell precursors that produced potentially pathogenic autoantibodies could be immortalized from the peripheral blood of the patients by EBV. In contrast, the frequency of EBV-induced B cell precursors that produced IgM anti-nRNP in patients with systemic autoimmune disease was comparable to that in healthy volunteers and greater than those that produced IgG and IgA anti-nRNP. Moreover, many of the clones that produced IgM antibodies against nRNP reacted with other autoantigens, such as double-stranded DNA, single-stranded DNA and rabbit IgG. These polyreactive IgM antibodies are believed to belong to the 'natural antibodies', to be coded by the germline immunoglobulin V genes, and to react with evolutionarily conserved structural cellular components, including nRNP. Our finding that nRNP is one of the target antigens for this polyreactive autoantibody may lead to the elucidation of the origin of the pathogenic IgG and IgA anti-nRNP antibodies found in sera from patients with systemic autoimmune diseases.

Adult↗

PubMed1991

Autoantibodies to the collagen-like region of C1Q deposit in glomeruli via C1Q in immune deposits.

The autoantibodies to the collagen-like region of C1q (CLR), purified from two patients with systemic lupus erythematosus, deposited in mouse glomeruli when human C1q was present in antigen-antibody complexes in glomeruli. The immune deposits with C1q in mouse glomeruli were achieved by the administration of cationized immune complexes containing human C1q. The presented data suggest that the autoantibodies to CLR could enhance the pathogenic role of immune complexes deposited in glomeruli by binding to C1q in immune deposits. These findings may explain the association of autoantibodies to CLR with proliferative lupus nephritis.

Animals↗

PubMed1991

Tubuloglomerular feedback response in rats with antithymocyte serum-induced glomerular lesions.

Glomerular function and tubuloglomerular feedback (TGF) responses were studied in rats treated with antithymocyte rabbit serum (ATS). Microscopic findings revealed extensive mesangial cell loss and injury, enlarged capillary lumen, and decreased tortuosity of glomerular capillaries. Whole kidney GFR and SNGFR were lower in ATS-treated rats than in control rats (1.04 +/- 0.04 vs 0.94 +/- 0.03 ml/min/g kidney weight, 32 +/- 2 vs 27 +/- 1 nl/min, respectively) due to a decrease in Kf (0.017 +/- 0.001 vs 0.021 +/- 0.001 nl/s/mmHg). The magnitude of the TGF responses of SNGFR was less in ATS rats than in control rats (17% +/- 4% vs 34% +/- 5%), but that of SFP was not significantly different (18% +/- 2% vs 23% +/- 1%). These results indicate that the mesangial cells are necessary for full expression of the TGF mechanism and suggest the involvement of changes in Kf in the TGF mechanism.

Animals↗

PubMed1990

The location of binding sites on C1q for DNA.

Previous studies have suggested that C1q reacts with DNA via both the globular region of C1q (GR) and the collagen-like region of C1q (CLR). In this study, the binding of dsDNA and ssDNA to GR and CLR was quantitated by a solid-phase assay. Both dsDNA and ssDNA bound to the GR and CLR of C1q in an ionic strength-dependent manner. Under physiologic salt concentrations, however, dsDNA and ssDNA bound preferentially to CLR and not to GR. The binding of dsDNA to C1q was not affected by heat inactivation of C1q or its exposure to pH 4.45, which abolished the binding of heat-aggregated human IgG (AHG) with C1q. The preincubation of the solid-phase C1q with AHG did not decrease the binding of dsDNA or ssDNA to the solid-phase C1q. These results indicate that the major sites for binding DNA to C1q are located in the CLR of C1q and are not overlapping with those for AHG or immune complexes.

Binding Sites↗

PubMed1989

Antibodies to the collagen-like region of C1q in sera of patients with autoimmune rheumatic diseases.

Antibodies to the collagen-like region of C1q have recently been observed in sera of patients with systemic lupus erythematosus (SLE). In this study, we documented that these antibodies were present in 47.3% of SLE patient sera, whereas they were uncommon in sera from patients with rheumatoid arthritis (2.8%) and Sjögren's syndrome (12.8%), as well as in normal sera (6.4%). Markedly elevated antibody levels (greater than 4 SD above the normal mean) were observed almost exclusively in sera of patients with SLE. Levels of antibodies to the collagen-like region correlated highly with levels of solid-phase C1q-binding IgG when analyzed by the C1q solid-phase assay for immune complexes (r = 0.87). We previously found that, after sucrose density gradient ultracentrifugation, a predominance of the solid-phase C1q-binding IgG in SLE sera sediments as monomeric IgG. These findings, together with the present data, indicate that reactivity of SLE patients' sera in the C1q solid-phase assay reflects primarily the presence of antibodies to the collagen-like region, and not the presence of immune complexes.

Arthritis, Rheumatoid↗

PubMed1989

IgG subclasses of antibodies to the collagen-like region of C1q in patients with systemic lupus erythematosus.

Low molecular weight C1q-binding IgG in the sera of patients with systemic lupus erythematosus consists of autoantibodies to the collagen-like region of C1q. In this study, the IgG subclass distribution of these autoantibodies was examined by radial immunodiffusion with polyclonal antibodies specific for each subclass. The purified antibodies to the collagen-like region of C1q possessed the IgG subclass distribution present in normal serum.

Antibodies↗

PubMed1989

Monocyte-mediated suppression of anti-DNA antibody production in healthy subjects.

Monocyte-depleted mononuclear cells (MNC) from healthy subjects synthesized IgM-class antibody to single-stranded DNA (anti-ssDNA) at significantly higher levels than unfractionated MNC. The increased production of IgM anti-ssDNA by monocyte-depleted normal MNC was inhibited to a greater degree than total IgM by addition of supernatants from autologous monocytes. Moreover, supernatants obtained from normal monocytes cultured with indomethacin retained this suppressive effect on IgM anti-ssDNA antibody production, suggesting that prostaglandin E2 may not be involved in the suppression. These results indicate that B cells programmed to produce IgM anti-ssDNA are present in the normal B cell repertoire, but may be suppressed by monocytes or by a soluble factor (or factors) from the monocytes.

Antibodies, Antinuclear↗

PubMed1988

Monocyte-mediated suppression of rheumatoid factor production in normal subjects.

The regulatory role of normal monocytes in the production of rheumatoid factor (RF) was investigated. Monocyte depletion from normal mononuclear cells (MNC) resulted in an elaboration of IgM RF in 18 of 20 subjects. The increased RF production was inhibited by the addition to the cultures of adherent cells or their culture supernatants. These observations demonstrate the suppressive role of normal monocytes in the production of RF. Supernatants obtained from normal monocytes cultured with indomethacin could suppress the RF production, suggesting that prostaglandin E2 may not be involved in the regulation of IgM RF production.

Biological Products↗

PubMed1988

Low-molecular weight C1q-binding immunoglobulin G in patients with systemic lupus erythematosus consists of autoantibodies to the collagen-like region of C1q.

The majority of C1q-binding IgG in sera of some patients with systemic lupus erythematosus (SLE) cosediments with monomeric IgG. This study was undertaken to provide definitive proof that the low-molecular weight C1q-binding IgG consists of autoantibodies to C1q. Monomeric C1q-binding IgG was isolated from five SLE plasmas by C1q affinity chromatography and gel filtration. All C1q-binding IgG preparations and their F(ab')2 fragments bound to both C1q and the collagen-like region of C1q by an ELISA. To rule out the possibility that small DNA-antiDNA immune complexes caused this binding activity, Fab' fragments of the C1q-binding IgG preparations were digested with DNase I to degrade any DNA. The Fab' fragments continued to bind to C1q and its collagen-like region after this treatment. C1q-binding IgG was heterogenous on isoelectric focusing. Interaction of C1q-binding IgG with solid-phase C1q was retained in 1 M NaCl, whereas the binding of DNA or heat-aggregated IgG to solid-phase C1q was abrogated or markedly diminished. The association constant of C1q-binding IgG with solid-phase C1q was 2.7 X 10(7) M-1. We conclude that low-molecular weight C1q-binding IgG in the studied patients with SLE consists of autoantibodies to the collagen-like region of C1q.

Autoantibodies↗

PubMed1987

C1q solid-phase radioimmunoassay: evidence for detection of antibody directed against the collagen-like region of C1q in sera from patients with systemic lupus erythematosus.

In earlier studies we showed that the C1q-binding IgG in the sera from patients with systemic lupus erythematosus (SLE) tested by C1q solid-phase radioimmunoassay is cofractionated with monomeric IgG on gel filtration and mostly binds to C1q via the F(ab')2 region. In this study, we found that C1q, even when stripped of its immune complex-binding globular regions by pepsin digestion, retained a substantial part of its ability to bind IgG from SLE sera, suggesting that the collagen-like region of C1q is involved in binding to the SLE IgG. Heat-inactivation of C1q also failed to abolish its ability to bind IgG from SLE sera. In contrast, the binding of C1q to heat-aggregated IgG was completely abrogated by these treatments. In addition, the reaction of heat-aggregated IgG with the solid-phase C1q was markedly dependent on ionic strength whereas the binding of IgG from SLE sera with the solid-phase C1q persisted at high concentrations of salt. These findings suggest that the Clq-binding IgG in SLE sera is, at least in part, antibody directed against the collagen-like region of C1q.

Autoantibodies↗

PubMed1984

C1q solid-phase radioimmunoassay: binding properties of solid-phase C1q and evidence that C1q-binding IgG complexes in systemic lupus erythematosus are not bound to endogenous C1q.

The binding properties of C1q solid-phase radioimmunoassay (C1q SPRIA) were examined, using heat-aggregated IgG (HAG) as the model of immune complexes (IC). The free, liquid-phase C1q, which was added to the C1q-coated tubes prior to the addition of HAG, had little inhibitory effect on binding of HAG to the solid-phase C1q, suggesting that the solid-phase C1q has a higher affinity for HAG than the liquid-phase C1q. On the other hand, more than 60% inhibition was seen when HAG was preincubated with the liquid-phase C1q. These binding properties of HAG to the solid-phase C1q in the presence of the liquid-phase C1q were not essentially altered by the heat inactivation or the addition of EDTA, suggesting that these pretreatments are not essential in C1q SPRIA. Next, in similar kinds of experiments, the binding properties of C1q-binding IgG complexes in SLE sera were investigated. In contrast to HAG, the binding capacity of IgG complexes in SLE sera to the solid-phase C1q was not inhibited by the preincubation with excess liquid-phase C1q. These findings suggest that C1q-binding IgG complexes in SLE sera detected by C1q SPRIA may not be bound to endogenous C1q in the circulation.

Antigen-Antibody Complex↗

PubMed1984

Characterization of C1q-binding IgG complexes in systemic lupus erythematosus.

The molecular size of C1q-binding immunoglobulin (Ig) G complexes in systemic lupus erythematosus (SLE) sera was studied by gel filtration using C1q solid-phase radioimmunoassay (C1q SPRIA). All 15 SLE sera tested contained predominantly small-sized IgG complexes, cofractionating with monomeric IgG. In contrast to heat-aggregated IgG, these small-sized IgG complexes retained C1q-binding activity even after pepsin digestion, exposure to low pH, or reduction and alkylation, suggesting that the F(ab')2 region is involved in C1q-binding activity of these complexes. To see whether anti-C1q antibodies or small antigen-IgG complexes, which bind to C1q via their antigens, are responsible for C1q-binding activity via the F(ab')2 region, the pepsin-digested Ig fractions of SLE sera were fractionated at high salt. C1q-binding activity in the fractions corresponding to the F(ab')2 region increased 2.5- to 3.9-fold at high salt. These results suggest that the C1q-binding, small-sized IgG complexes may be comprised mostly of anti-C1q antibodies and that some of the antibodies, which are dissociated with their antigens at high salt, might be cross-reactive with C1q.

Adult↗

PubMed1984