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Biomedical subjects

E M Tan

Publications and source records attributed to E M Tan.

At least 253 records · Page 14Linked to original sources
PubMed1981

Distribution of kinetochore (centromere) antigen in mammalian cell nuclei.

Antigens associated with mammalian centromeres were localized at the high and electron microscopic levels using the peroxidase-labeled antibody method. The antibody used was of a type naturally occurring in the sera of patients with scleroderma. At the light microscopic level, it reacts specifically with the centromere regions of chromosomes in a variety of mammalian species and strains in discrete foci in interphase nuclei. We find that the number of foci approximates the number of chromosomes present in the various cell types. At the ultrastructural level, the antigenic foci are confirmed to lie in the kinetochore regions of each chromosome. In interphase nuclei, the antigenic foci were usually associated either with the inner surfaces of the nuclear envelope or with the nucleoli. These observations indicate that the centromere regions of the chromosomes in interphase are not randomly distributed within the nucleus but are usually fixed either to the inner surface of the nuclear envelope or to nucleoli.

Animals↗
PubMed1981

Nonhistone nuclear antigens reactive with autoantibodies. Immunofluorescence studies on distribution in synchronized cells.

Sera from patients with certain autoimmune diseases tht contained autoantibodies to nonhistone nuclear antigens were used as reagents in an indirect immunofluorescent study. The distribution of these nuclear antigens was determined in synchronized human B lymphoid cells. Autoantibodies to Sm antigen, nuclear ribonucleoprotein complex and SS-B antigen were used. Although all three nonhistone antigens appeared to show speckled nuclear straining patterns in the Go phase, different patterns of staining were present at other periods of the cell cycle. The SS-B antigen showed a distinctly nucleolar localization during the G1/early S phase. These studies demonstrate that autoantibodies occurring in certain human diseases can be useful reagents for the immunohistological localization of nuclear macromolecules and for tracing their pathways during different phases of cell growth and differentiation.

Antibodies, Antinuclear↗
PubMed1981

Human skin fibroblasts in culture: procollagen synthesis in the presence of sera from normal human subjects and from patients with dermal fibroses.

Various dermal fibrotic conditions, such as progressive systemic sclerosis, localized morphea and familial cutaneous collagenoma, are characterized by excessive deposition of collagen in the skin. In the present study, we examined the possibility that a circulating serum factor(s) is responsible for increased collagen production in these diseases. The effects of human serum on the synthesis of procollagen were examined by incubating normal human dermal fibroblasts with [3H]proline and varying concentrations of dialyzed heat-inactivated serum. The synthesis of procollagen was measured as formation of nondialyzable [3H]hydroxyproline and collagenase-digestible 3H]polypeptides. In the absence of serum little procollagen was formed but the synthesis was markedly stimulated by the addition of normal serum in a concentration-dependent manner. THe ratio of genetically distinct 3H-procollagens of type I and type III, assayed by DEAE-cellulose chromatography and SDS-polyacrylamide gel electrophoresis after limited pepsin proteolysis, was unaffected by the addition of serum. Thus, normal human serum contains a nondialyzable factor(s) which stimulates the synthesis of procollagens type I and type III equally. Sera from 5 patients with progressive systemic sclerosis, 3 with localized scleroderma, and 2 with familial cutaneous collagenoma were also tested. Sera from these patients failed to stimulate 3H-procollagen production more than sera from healthy age-matched controls. Therefore, no increased quantities or qualitatively aberrant factors were shown to be present in the sera of these patients.

Blood Physiological Phenomena↗
PubMed1981

Seroepidemiological study of relationships between Epstein-Barr virus and rheumatoid arthritis.

To elucidate the relationship between Epstein-Barr virus (EBV) and rheumatoid arthritis (RA), we measured antibodies to RA-associated nuclear antigen (anti-RANA) and three other EBV-related antigens in the sera of RA patients and controls. Our study groups consisted of 89 patients with definite or classical RA, mean age 56, male/female ratio 47:42; and 53 normal and osteoarthritis controls, mean age 51, male/female ratio 25:28. In addition to anti-RANA, we measured antibodies to viral capsid antigen (anti-VCA), early antigen (anti-EA) and EBV-associated nuclear antigen (anti-EBNA). Anti-RANA was detected in 71% of RA patients but in only 6% of controls. Elevated anti-VCA titers (greater than 1:160) were more common in RA patients than controls, 31% compared with 15%. The geometric mean titer of anti-VCA was significantly higher iun the RA group, 133 compared with 58. Anti-EA was present in 53% of RA patients but only 19% of controls. Anti-EA in elevated titers (greater than 1:20) was present in 26% of RA patients but only 7% of controls. Characterization of the anti-EA antibodies revealed that the RA patients reacted primarily with the diffuse component, whereas the majority of the controls reacted with the restricted component of the EA complex. In contrast, the frequencies, distributions, and geometric mean titers of anti-EBNA were not significantly different between the two groups. Correlative analysis of these antibodies showed highly significant relationships between anti-VCA and anti-EA, and anti-RANA and anti-EBNA in the RA group. These data are compatible with the interpretation that RA patients have either more active EBV infections than controls or an altered regulation of their immune response to this infectious agent.

Antibodies, Viral↗
PubMed1981

Isolation of circulating immune complexes by conglutinin and separation of antigen from dissociated complexes by immobilized protein A.

A method for the isolation of complement-fixing immune complexes from human serum and the separation of antigen from antibody is described. In order to isolate the complexes, we used soluble bovine conglutinin in a three-step procedure: (1) serum containing immune complexes is reacted with conglutinin in the presence of 10 mM calcium; (2) the conglutinin-bound immune complexes are precipitated by anti-conglutinin rabbit serum; (3) the precipitate is washed and the complexes are eluted from the precipitate by EDTA (pH 7.5) which chelates calcium and releases C3-associated immune complexes from conglutinin. To separate the antigen from the antibody, the isolated complexes are acid-dissociated (pH 3.0), and the antibody is absorbed to staphylococcal protein A conjugated to Sepharose leaving the antigen in solution. The antibody bound to Sepharose-protein A is recovered by elution with 3.5 M magnesium chloride. This procedure permitted the isolation of immune complexes from sera of hepatitis B surface antigen (HBsAg) positive chronic active hepatitis. In addition, immune complexes were isolated from sera of patients with rheumatoid arthritis, systemic lupus erythematosus and primary biliary cirrhosis. The isolated immune complexes contained IgG, IgM, C3 and albumin. Specific antibodies such as rheumatoid factors, anti-nuclear antibodies and antimitochondrial antibodies in varying titres have been found to be present in the isolated immune complexes. The conglutinin method has proven to be a useful technique for the isolation of immune complexes and for the identification of antibody and could be applied to the identification of the antigen in immune complexes.

Antigen-Antibody Complex↗
PubMed1981

Reactions between polyribonucleotides and low density lipoproteins in sera of patients with progressive systemic sclerosis.

A high percentage (58%) of sera from patients with progressive systemic sclerosis reacted with synthetic polyribonucleotides to give precipitin lines. This was demonstrated by counterimmunoelectrophoresis. The synthetic polyribonucleotides included polyuridylic acid (poly U), polyadenylic acid (poly A), and co-polymers of poly A-poly U. The reactive factor in serum was not immunoglobulin but was associated with low density lipoprotein.

Antibodies↗
PubMed1980

Evidence for a subset of rheumatoid factors that cross-react with DNA-histone and have a distinct cross-idiotype.

Cross-reactivity of a monoclonal rheumatoid factor with an antigen present on IgG and DNA-nucleoprotein was demonstrated, and evidence presented that the combining site of the antibody was involved in the reaction. The antigen on the DNA-nucleoprotein was shown to involve both DNA and histone fraction H2A + H2B and was trypsin sensitive. The relative binding affinity of the antibody appeared to be greater for IgG than the DNA-histone antigen. Similar polyclonal cross-reactive rheumatoid factors were found in a variety of diseases. A high incidence was found among patients with rheumatoid arthritis and mixed connective tissue disease. None were detected in patients with systemic lupus erythematosus and idiopathic cryoglobulinemia. Studies on one representative isolated polyclonal rheumatoid factor demonstrated the same reactivity with DNA-histone H2A + H2B as the monoclonal antibody. Cross-idiotype studies using antigen-binding inhibition methods demonstrated the same cross-idiotype on the polyclonal and the monoclonal rheumatoid factor which reacted with DNA-histone. This cross-idiotype was shown to be distinct from the cross-idiotypes previously demonstrated on monoclonal IgM proteins with anti-gamma-globulin activity.

Binding Sites, Antibody↗
PubMed1980

Diversity of antinuclear antibodies in progressive systemic sclerosis. Anti-centromere antibody and its relationship to CREST syndrome.

Antinuclear antibodies were demonstrated in the sera of 43 of 45 (96%) patients with progressive systemic sclerosis (22 of 24 with diffuse scleroderma and 21 of 21 with the CREST syndrome variant). This high percentage of positive reactions resulted from the use of a tissue culture substrate (HEp-2) to detect antinuclear antibodies by the indirect immunofluorescent method. Patterns of nuclear staining included diffuse fine speckles, large coarse speckles, nucleolar and centromere staining. When organ sections such as mouse kidney were used as substrate for the detection of antinuclear antibodies, nucleolar staining and centromere staining were the two patterns most frequently overlooked. Three types of antibodies appeared to be highly specific for scleroderma: antibody to Scl-70 antigen, antibody to centromere, and antinucleolar antibody. The anti-centromere antibody appeared to be highly selective for the CREST variant of progressive systemic sclerosis.

Antibodies, Antinuclear↗
PubMed1980

Autoantibody to centromere (kinetochore) in scleroderma sera.

Sera from patients with scleroderma contained several autoantibodies to nuclear antigens which were distinguished by different patterns of nuclear immunofluorescence staining. One of these autoantibodies reacted with centromeric regions of chromosomes. In chromosome spreads, the staining appeared as two small spheres at the centromere, resembling kinetochores. The antigenic determinant appeared to be a protein or polypeptide tightly bound to DNA. The autoantibody was reactive with centromeres of cells derived from humans, mice, and Chinese hamsters. The autoantibody was present in high frequency in the calcinosis/Raynaud's phenomenon/esophageal dysmotility/sclerodactyly/telangiectasia variant (CREST) of scleroderma.

Antibodies, Antinuclear↗
PubMed1980

Preciitating antibodies to mitochondrial antigens in patients with primary biliary cirrhosis.

Sera of patients with primary biliary cirrhosis (PBC) were examined for the presence of precipitating antibodies to sonicated rat liver mitochondrial (M) fraction. Three distinct precipitating systems observed in double immunodiffusion were identified and called M-A, M-B and M-C. Unsonicated mitochondria did not form precipitin lines. Precipitating system M-A was found in nineteen of twenty (95 percent) sera from PBC. The mitochondrial antigen of M-A system had the unusual property of being resistant to enzymatic digestion with deoxyribonuclease (DNase), ribonuclease (RNase) and trypsin under standard conditions. The titres of antibody to M-A antigen correlated (P less than 0.05) with titres of mitochondrial immunofluorescence staining on unfixed mouse kidney sections. Precipitating systems M-B and M-C were present in seven of twenty ribonuclease and trypsin but resistant to ribonuclease indicating that it could be DNA-protein complex. The M-C antigen was destroyed by trypsin suggesting its protein character, but it was difficult to determine if nucleic acids might also be associated with antigenicity. The antibodies to mitochondrial antigens were not present in normals (fifteen health adults), systemic lupus erythematosus (forty patients), rheumatoid arthritis (fifteen patients) and chronic liver diseases (fifteen patients). The antibodies did not show identity with antibodies to ribosomal ribonucleo-protein and other known nuclear antigens previously reported. The data confirm previous reports concerning the heterogeneity of mitochondrial antibodies present in sera of patients with PBC. The antibody to M-A antigen appeared to be a diagnostically useful immunological marker since it was present in the majority of patients with PBC.

Adult↗