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Biomedical subjects

M Simonsen

Publications and source records attributed to M Simonsen.

67 records · Page 4Linked to original sources
PubMed1969

Antithrombin 3. Protection against death after injection of thromboplastin.

Intravenous injection of autologous lipoprotein (thromboplastin) or thrombin produced a lethal, hemorrhagic syndrome in chicken embryos. The embryos could be protected from this fatal result by injection of antithrombin III, an alpha(2)-globulin (molecular weight 60,000 to 80,000) purified from human, bovine, and guinea pig blood. Heparin also protected the embryos, but other inhibitors were less protective.

Alpha-Globulins↗
PubMed1969

The frequency of antigen-sensitive cells in tissue transplantation. A commentary on clonal selection.

Graft-vs.-host (GVH) reactions were performed in chicken embryos by intravenous injection of adult chicken blood dilutions, and the result was scored by weighing the spleens as well as by karyological identification of host and donor metaphases. From the frequency of detectable signs of GVH reaction when low doses of donor cells were injected into hosts containing one foreign allele of the B locus it is concluded that 1-2% must be a minimum estimate for the frequency of antigen-sensitive cells of a given specificity in this system. It is not found possible to reconcile the findings with the strictest form of clonal selection which postulates a single receptor specificity per clone of antigen-sensitive cells.

Animals↗
PubMed1967

Primary immune response in grafted cells. Dissociation between the proliferation of activity and the proliferation of cells.

The primary immune response elicited by host antigens in a grafted population of immunologically competent cells has been compared in conditions where the same dose of parental cells were grafted simultaneously to F(1) hybrid embryos of 13 or 17 days of age. The enlarged chimeric spleens harvested 4 days later were analyzed for donor cell proliferation by using the sex chromosomes as karyological markers, and for proliferation of immunological activity by means of transfer to secondary hosts of the same genotype. Whereas the total number of dividing donor cells were on the average 16 times higher in 17-day than in 13-day hosts, the recovery of immunological reactivity showed a 6- to 7-fold difference in the opposite direction. The experiments cast doubt on the proposition that cellular proliferation is necessary for development of a primary immune response. They suggest that there exists an alternative way in which a primary immune response may unfold from involving a few to involving a much larger number of cells.

Animals↗
PubMedDate not supplied

Possible roles of compound membrane receptors in the immune system.

A compound receptor is defined as a molecular complex which attains its final, biologically active structure by rearrangement and assembly in the membrane of several structural subunits. The existence of such receptor complexes is strongly suggested by experiments which demonstrated a very close association between certain ligand (primarily insulin) receptors and the major histocompatibility complex (MHC) antigens. We present here speculations on the possible role of MHC as a structural part of a multitude of receptors with different biological functions, and we argue that recent immunological data on minor histocompatibility antigens, antigen-presenting cells and T-lymphocyte receptors fit into this hypothesis.

Animals↗