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Biomedical subjects

N Tada

Publications and source records attributed to N Tada.

At least 109 records · Page 6Linked to original sources
PubMed1987

Myeloproliferative disorder due to abnormal production of hematopoietic stimulators.

A new kind of myeloproliferative disorder (L-8313) has been discovered. It was transplantable into syngeneic mice with spleen cells. The mice showed hepato-splenomegaly with a marked leukocytosis and anemia 3 weeks after transplantation of L-8313 cells. The number of GM-CFU and CFU-S per spleen increased to more than 40 times normal. The results of chromosomal and PGK analysis demonstrated that these increased stem cells were of host origin. Both the culture medium of the spleen cells and the serum from L-8313 bearing mice showed high levels of IL-3, BPA and CSF. Consequently, hematopoietic cells of the host mice underwent remarkable proliferation in response to these stimulating factors when L-8313 cells were transplanted. We also have been successful in establishing an in-vitro cell line and have maintained it for over one year. The phenotype of L-8313 cells was Thy 1.2 positive. Some L-8313 cells showed a positive acid phosphatase reaction but the cytochemical character of myeloid lineage was not observed. Therefore, L-8313 is considered to be a T-cell derived hematopoietic regulatory cell neoplasm with the ability to produce several hematopoietic stimulating factors.

Anemia↗
PubMed1985

Polymorphism of murine major histocompatibility Class I antigen: assignment of putative allodeterminants to distinct positions of the amino acid sequence within the first external domain of the antigen.

Forty-five new monoclonal antibodies reacting with the mouse H-2Dd antigen have been established. The specificities of 34 of these antibodies were mapped into the first external domain (N) of the Dd antigen by testing reactivities with the products of mosaic H-2 genes in which the coding sequences of the first and/or the second external domains of the H-2Dd genes were recombined in vitro with the remaining portion of the H-2Ld gene. These antibodies reacted with at least 13 distinct allodeterminants located in the N domain, composed of 91 amino acids, as judged from panel tests carried out on various H-2 haplotypes. To assign possible positions of antigenic determinants of these and other anti-H-2Dd antibodies, we compared primary sequences of seven H-2 antigens and searched for correspondence between the pattern of amino acid substitutions in the N domain, allowing 15 positions to be assigned for the antigenic sites. These putative antigenic determinants were assessed for possible relationships with several parameters of protein secondary structure postulated according to predictive methods. Many of these sites appear to be associated with greatest local hydrophilicity, known to correlate with sites of antibody binding in various proteins. We therefore propose that some of the correspondences found in this work represent structural correlates of allodeterminants.

Amino Acid Sequence↗
PubMed1984

Studies of the mouse Ly-6 alloantigen system. II. Complexities of the Ly-6 region.

The discovery of several monoclonal antibodies provided the impetus to revisit the Ly-6 group of antigens. Our serological data point to the existence of at least five separate Ly-6 antigens. They are distinguished by the patterns of their tissue expression as (1) the classical Ly-6 alloantigen of peripheral lymphocytes (Ly-m6.2A), (2) a bone marrow cell-restricted antigen (Ly-m6.2B), (3) an antigen shared by bone marrow cells and peripheral lymphocytes (Ly-m6.2C, possibly identical with H9/25), (4) an antigen expressed on bone marrow cells, thymocytes, and peripheral lymphocytes (Ly-m6.2D), and (5) an antigen occurring exclusively on lymphoblasts (Ly-m6.1E, similar to Ala-1). ThB is a sixth distinct antigen of the group. The assumption that separate antigens exist is supported by distinctive distribution patterns in normal and neoplastic tissues. The genes controlling Ly-6 antigens are closely linked, as they are transmitted as two haplotypes only. One incidence of a crossover within the Ly-6 region was observed: the Ly-6B.2 alloantigen was expressed in NZB mice, which type Ly-6.1 for other Ly-6 specificities.

Animals↗
PubMed1984

Monoclonal antibodies detect polymorphic determinants shared by I-A and I-E antigens.

Binding data on inbred mouse strains and immunochemical isolation of Ia antigens with subsequent separation on non-reduced/reduced two-dimensional gels provide evidence for the cross-reactivity of monoclonal antibodies with I-A and I-E products. Thus two monoclonal antibodies were found to react with A alpha A beta as well as E alpha E beta dimers. One of these mAbs, K22 -42, reacts with the precursor form of E beta chain of B10.GD mice which is associated with the invariant chain (Ii). This indicates that the respective determinant on E beta is formed prior to association of E beta with E alpha.

Animals↗
PubMed1983

Heterogeneity of very-low-density lipoprotein metabolism in hyperlipidemic subjects.

Very-low-density lipoproteins (VLDL) are triglyceride-rich lipoproteins that have been shown, by physicochemical means, to comprise more than one group of particles. Because of the potential atherogenicity of catabolized VLDL, we used the technique of heparin-affinity chromatography to separate VLDL into two classes of particles, one of which appears to contain partly catabolized VLDL. This observation is based on the higher cholesterol/triglyceride and higher apoprotein E/apoprotein C ratios in VLDL particles that are bound to heparin, resembling in this way intermediate-density lipoproteins (IDL), which are certainly derived in the main through VLDL catabolism. Further studies showed separate metabolic characteristics for the unbound and heparin-bound VLDL particles. Radiolabeled whole VLDL or unbound particles were reinjected into seven hypertriglyceridemic subjects and the kinetics studied in serial samples of plasma over the next 18-48 hours. The specific radioactivity-time curves of apoprotein B in the unbound and bound particles showed that the bound particles were derived wholly or partly from the unbound particles and in turn, were the precursors of IDL. This confirmed that heparin-bound VLDL particles represented VLDL undergoing catabolism, although in one subject about one-half of the bound particles appeared to have an origin other than through VLDL catabolism. These studies show that VLDL metabolism is heterogeneous, that the kinetics of total VLDL must be interpreted accordingly, and that the technique of heparin-affinity chromatography can be used for more detailed studies of VLDL.

Adult↗