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O G Segurado

Publications and source records attributed to O G Segurado.

30 records · Page 2Linked to original sources
PubMed1990

Both HLA class II and class III DNA polymorphisms are linked to juvenile rheumatoid arthritis susceptibility.

HLA-DR5 and DRw8 are not significantly linked to juvenile rheumatoid arthritis (JRA) in the Spanish population. However, we have found restriction fragment length polymorphisms (RFLPs) beta DR-2.9-kb-EcoRI and C4-14.3-kb-EcoRI, that correlate significantly with JRA. Eighty-six percent of our patients present either HLA-DR5 or the beta DR-2.9-kb-EcoRI allogenotope or lack the C4-14.3-kb-EcoRI allogenotope compared to 48% in controls; however, these particular DR and C4 RFLPs may not represent the corresponding DRB1 or C4 genes but rather neighboring ones which may be relevant to confer JRA susceptibility. The C4-14.3-kb-EcoRI RFLP decrease in patients may reflect a decrease in C4 B "long" phenotypes. Also, both RFLPs are the only markers able to identify most of the JRA patients in our population. On the other hand, the findings of both class II and III genes associated to JRA may reflect the existence of epistatic interactions (cis or trans) within the HLA gene cluster which lead to a particular pathology in certain diseases.

Arthritis, Juvenile↗
PubMed1990

Shared SstI RFLPs by HLA-Aw19, A23/24 and A3/11 crossreacting groups.

Three novel restriction fragment length polymorphisms (RFLPs) have been identified using a pan-HLA class I probe and the endonuclease SstI. This study, in conjunction with previously reported SstI RFLPs, now allows the identification of the HLA-crossreacting antigens Aw19 (A29/30/31/32/w33), A23/24 and A3/11 by specific hybridization patterns with a single enzyme/probe combination. Three of the corresponding polymorphic SstI restriction sites map within the HLA-A gene and generate two allelic RFLPs (5.06, 5.92 kb) and one single RFLP (5.92 kb) that show an absolute correlation with HLA-A23/24 and A29/32 crossreacting antigens, respectively. However, other SstI RFLPs (7.97, 9.4, 9.6, 9.8 and 13.34 kb), also linked to HLA-A crossreacting antigens, map outside the HLA-A gene and probably correspond to non-HLA-A,B,C class I genes in strong linkage disequilibrium with the HLA-A gene. These data show that HLA-A crossreacting antigens share more SstI RFLPs than neighboring non-HLA-A,B,C class I genes or pseudogenes; also, this has raised the possibility that some crossreacting HLA-A alloantisera might additionally recognize shared antigenic determinants in non-HLA-A,B,C proteins since the HLA-Aw19 crossreactivity cannot be fully explained by analyzing the HLA-A amino acid sequence.

Chromosome Mapping↗
PubMed1989

Simultaneous detection of allotypes in native and activated human C2 by isoelectric focusing and silver staining.

A simple and highly sensitive analytical isoelectric focusing (IEF) technique using immunofixation with anti-C2 serum followed by silver staining has been developed in order to study simultaneously the structural polymorphism of both native C2 and C2 activation fragments (C2a MW 74,000 and C2b MW 34,000). Structural C2 polymorphism of C2*B and C2*C allotypes (but not of C2*A1) was found to be associated with the C2a fragment, whereas C2b appears to display no polymorphism. Commercially available IEF gels and C2 antisera gave reproducible allotyping data and make this technique of general use for densitometric analysis of native and activated C2. In vivo C2 activation was studied through C2a/native C2 area ratios obtained by computerized densitometry. Significantly lower ratios were observed in healthy individuals than in patients with systemic lupus erythematosus (SLE), reflecting an abnormally high classical pathway activation of complement in SLE. This methodology may be of value for immunogenetic and functional studies of other complement components.

Alleles↗
PubMed1989

Two BF F subtypes, but no BF S, BF F1 or BF S07 subdivision, are found by isoelectric focusing.

When studied by immunoelectrophoresis the factor B (BF)*F allele is a monomorphic protein, but by using isoelectric focusing (IEF), it turns out to be polymorphic. Two BF*F allelic subdivisions, BF*FA and BF*FB, were detected in samples from unrelated Spanish donors; *FA and *FB are in Hardy-Weinberg equilibrium, segregate as autosomal codominant alleles in families, and BF*FA (but not BF*FB) is found to be in linkage disequilibrium with B44 and DR7 and is within the A29, B44, Bw4, Cx, CFA31, DR7, DRw53, DQ2 haplotype. Furthermore, BF FA individuals have a higher BF serum concentration than the BF FB individuals. The subdivision of BF S observed with IEF was found to be due to nonspecific BF S cleavage by serum proteases in inadequately collected or aged samples. Thus, the subdivision of BF S is spurious and was not found in our sera. BF F1 and BF S07 could not be further subdivided by IEF in our subjects. The BF F1 banding pattern was characterised by the presence of a cathodal band which corresponds to the Bb activation fragment. Finally, IEF combined with immunoblotting and monoclonal Ba and Bb antibodies may be used for accurately distinguishing BF phenotypes and doubtful bands.

Alleles↗
PubMed1988

Selective concentration of anti-Purkinje cell antibody in the CSF of two patients with paraneoplastic cerebellar degeneration.

An anti-Purkinje cell antibody (APCA) was found in serum and CSF of 2 patients with paraneoplastic cerebellar degeneration (PDC) and breast carcinoma. Integrity of the blood-brain barrier (BBB) was normal in one patient and slightly damaged in the other. In both patients CSF IgG index was normal, but CSF/serum APCA ratio and CSF IgG APCA index were elevated suggesting that a selective concentration of the APCA in CSF occurs in patients with PCD. This feature supports the hypothesis that APCA may play a role in the pathogenesis of PCD.

Adult↗
PubMed1986

Clinical significance of serum and CSF findings in the Guillain-Barré syndrome and related disorders.

Clinical data and the serum and cerebrospinal fluid (CSF) findings of 71 patients with Guillain-Barré syndrome (GBS), 7 with Fisher syndrome and 24 with chronic inflammatory polyradiculoneuropathy (CIP), were analysed. Isoelectric focusing of serum and CSF together with different formulae and diagrams were applied to study blood-CSF barrier (BCB) function and possible intrathecal IgG synthesis. The CSF total protein concentration and its IgG percentage depended mainly on the degree of BCB damage, which correlated with the clinical course. Our investigations suggest that oligoclonal IgG of CSF from these patients comes essentially from serum. In the group of GBS patients, oligoclonal IgG was transitory and correlated significantly with the development of BCB damage, cranial neuritis and severity of the disease. CIP patients showed a stable IgG pattern, which varied slightly after immunosuppressive therapy.

Adolescent↗
PubMedDate not supplied

Autoimmunogenic HLA-DRB1*0301 allele (DR3) may be distinguished at the DRB1 non-coding regions of HLA-B8,DR3,Dw24 and B18,DR3,Dw25 haplotypes.

A novel TaqI restriction fragment length polymorphism (RFLP) of 4.15 kb is reported using a DR beta probe (pRTV1). This fragment corresponds to the DRB1 locus and allows the subdivision at the DNA level of the DRB1*0301 allele (DR3 antigen), which had not previously been reported. Both splits also distinguish each of the two DR3-bearing extended haplotypes (HLA-B8,SCO1,DR3,DQw2,Dw24 and B18,F1C30,DR3,DQw2,Dw25) found associated to several autoimmune diseases as insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus (SLE) and myasthenia gravis. The fact that no polymorphism in the DRB1*0301 coding DNA sequence has been detected indicates that DRB1*0301 intronic, regulatory of neighbouring sequences might also contribute to differential disease associations (and pathogenic mechanisms) found linked to each of the two DR3-bearing haplotypes, i.e. IDDM and B8,DR3,Dw24 in North European/American Caucasoids vs IDDM and B18,DR3,Dw25 in Mediterraneans; SLE and B8,DR3,Dw24 in children vs SLE and B18,DR3,Dw25 in Spanish adults.

Autoimmune Diseases↗
PubMedDate not supplied

PSA standardization: a review of NCCLS, Stanford and Abbott efforts.

The wide variances between prostate specific antigen (PSA) values for various assays and the demonstration that many of these differences are due to calibration differences has resulted in efforts to develop standards for PSA. Two major efforts are underway in the USA. The National Committee for Clinical Laboratory Standards (NCCLS) has published proposed guidelines for the purification and characterization of PSA and PSA-ACT (alpha-1-antichymotrypsin) complexes for primary standards. Furthermore, the Second Stanford PSA Conference proposed a mixture of 90% PSA-ACT and 10% PSA (90:10 standard) with a biochemically defined concentration to calibrate total PSA assays. Significant improvements in agreement between assays was observed with the 90:10 standard as compared to results with kit calibrators. The NCCLS has reviewed and adopted the 90:10 proposal. Thus, biochemically defined standards are preferred over immunoassay defined standards due to differences in assays and laboratory methods. The use of the 90:10 standard will be a major step towards improving the agreement between PSA immunoassays.

Calibration↗