Eng M. Tan

Bio: Eng M. Tan is an academic researcher from Scripps Research Institute. The author has contributed to research in topics: Antigen & Autoantibody. The author has an hindex of 47, co-authored 71 publications receiving 30110 citations. Previous affiliations of Eng M. Tan include University of Pittsburgh & University of Vermont.

Antibodies reacting with ribosomal ribonucleoprotein in connective tissue diseases

Abstract: Precipitating antibody to an antigen present in cytoplasm was detected in the sera of 7 patients with systemic lupus erythematosus, 1 patient with an overlap syndrome of systemic lupus erythematosus and rheumatoid arthritis, and 1 patient with mixed connective tissue disease. By physicochemical and enzymatic studies, the antigen was shown to have the properties of ribosomal ribonucleoprotein (r-RNP). Cytoplasmic staining in immunofluorescence was observed with all the 9 sera containing antibodies to r-RNP. In certain cases, cytoplasmic staining was associated with nucleolar staining. Antibody to r-RNP is different in immunologic specificity and clinical significance from antibody to nuclear RNP and is present primarily in patients with systemic lupus erythematosus.

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

Abstract: 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.

Nuclear autoantigen p330d/CENP-F: A marker for cell proliferation in human malignancies

Abstract: p330d, also known as CENP-F, is a newly characterized cell cycle specific nuclear autoantigen which is associated both with the centromeres and the nuclear matrix. It is expressed in low amounts in G0/G1-cells and accumulates in the nuclear matrix during S-phase with a maximum expression in G2/M-cells. In the present study we have investigated if p330d/CENP-F could be used as a marker for proliferation in different human malignancies. A flow cytometric method was developed by which p330d/CENP-F expression and DNA-content could be assessed on hematopoietic and solid tumors. Twenty-four different human hematopoietic malignancies, 12 breast cancers, and several cell lines were analyzed and the number of p330d/CENP-F positive cells and the S-phase fraction were determined. The percentage of p330d/CENP-F positive cells correlated with the fraction of S-phase cells in all human malignancies tested. Various cell lines revealed a similar cell cycle specific distribution. The association of p330d/CENP-F with the nuclear matrix facilitated the flow cytometric analysis of this protein due to its resistance to different preparation and fixation procedures. In summary, p330d/CENP-F seems to be a potentially valuable proliferation marker which can be applied to different tumors.

Mechanism of complement activation by radiographic contrast media.

Abstract: Activation of the complement system by radiographic contrast media (RCM) was demonstrated by in vitro haemolytic and immunological assays. Such activation was found to be a function of the RCM molar concentration. Iodipamide was the most active of five RCM tested. When RCM was incubated with normal human serum (NHS) in the presence of ethylene glycol-tetra-acetic acid and magnesium ions, conditions which block activation of the classical pathway but permit activation of the alternative pathway, haemolytically active C3, properdin and factor B were found to be decreased but haemolytically active C4 was normal. Using counterimmunoelectrophoresis, the activation of complement was further demonstrated by detection of C3 and factor B-split products. Finally, when radiolabelled complement proteins were reacted with RCM in vitro and studied by density-gradient ultracentrifugation, it was demonstrated that a large complex was formed with a sedimentation of 22S, similar in characteristics to the C5b-C9 complex. It was postulated that the mechanisms of in vitro consumption of complement by RCM was mainly through the alternative pathway.

Electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets: procedure and some applications.

Abstract: A method has been devised for the electrophoretic transfer of proteins from polyacrylamide gels to nitrocellulose sheets. The method results in quantitative transfer of ribosomal proteins from gels containing urea. For sodium dodecyl sulfate gels, the original band pattern was obtained with no loss of resolution, but the transfer was not quantitative. The method allows detection of proteins by autoradiography and is simpler than conventional procedures. The immobilized proteins were detectable by immunological procedures. All additional binding capacity on the nitrocellulose was blocked with excess protein; then a specific antibody was bound and, finally, a second antibody directed against the first antibody. The second antibody was either radioactively labeled or conjugated to fluorescein or to peroxidase. The specific protein was then detected by either autoradiography, under UV light, or by the peroxidase reaction product, respectively. In the latter case, as little as 100 pg of protein was clearly detectable. It is anticipated that the procedure will be applicable to analysis of a wide variety of proteins with specific reactions or ligands.

Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus.

Abstract: In 1982, the Diagnostic and Therapeutic Criteria Committee of the American College of Rheumatology (ACR)published revised criteria for the classification of systemiclupus erythematosus (SLE) (1). During the ensuing decade several investigators, including Drs. Graham Hughes and Donato Alarcon-Segovia, among others, have described the presence and clinical associations or antiphospholipid antibodies in patients with SLE, as well as the occurrence of theprimary antiphospholipid syndrome (2-5). In 1992, Piette and colleagues suggested that the ACR revised criteria be reevaluated in light of the above discoveries (6).

Development of criteria for the classification and reporting of osteoarthritis: Classification of osteoarthritis of the knee

Abstract: For the purposes of classification, it should be specified whether osteoarthritis (OA) of the knee is of unknown origin (idiopathic, primary) or is related to a known medical condition or event (secondary). Clinical criteria for the classification of idiopathic OA of the knee were developed through a multicenter study group. Comparison diagnoses included rheumatoid arthritis and other painful conditions of the knee, exclusive of referred or para-articular pain. Variables from the medical history, physical examination, laboratory tests, and radiographs were used to develop sets of criteria that serve different investigative purposes. In contrast to prior criteria, these proposed criteria utilize classification trees, or algorithms.

Evaluation of diagnostic criteria for ankylosing spondylitis. A proposal for modification of the New York criteria.

Abstract: The New York and the Rome diagnostic criteria for ankylosing spondylitis (AS) and the clinical history screening test for AS were evaluated in relatives of AS patients and in population control subjects. The New York criterion of pain in the (dorso) lumbar spine lacks specificity, and the chest expansion criterion is too insensitive. The Rome criterion of low back pain for more than 3 months is very useful. Our study showed the clinical history screening test for AS to be moderately sensitive, but it might be better in clinical practice. As a modification of the New York criteria, substitution of the Rome pain criterion for the New York pain criterion is proposed.