The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
Insulin, as well as other ligands which increase intracellular guanosine 3',5'-cyclic monophosphate (cGMP), augments thymic-derived (T)- lymphocyte effector activity as revealed by alloimmune lymphocyte-mediated cytotoxicity. The observation that insulin binds only to monocytes among circulating nonimmune human mononuclear cells fosterd reexamination of the mechanism by which insulin augments T-lymphocyte function. This report concerns a test of the hypothesis that the T cell is directly affected by insulin and that an insulin receptor emerges upon T lymphocytes consequent to immune activation. Spleens were removed from rats skin grafted across a major histocompatibility barrier. Lymphocytes were harvested from Ficoll-Hypaque density gradients and subsequently enriched for T cells by passage over one or two nylon wool columns. This population was composed of more than 98% T cells as assessed by surface marker techniques (Ig staining, erythrocyte antibody, and erythrocyte antibody complement rosetting, anti-T staining). There was no loss of augmentation of lymphocyte-mediated cytotoxicity induced by insulin, carbamycholine, and 8-bromo-cGMP in the purified cells when compared to unfractionated cells 7 days after transplantation. 125I-insulin bound saturably to the allostimulated T-enriched lymphocytes with maximum binding at 12.8 +/- 0.2 pg and a dissociation constant at equilibrium of 1.3 nM. In contrast, insulin receptors were not present on nonimmune T-enriched cells or on T cells from animals that received syngeneic grafts. The affinity of the lymphocyte insulin receptor was similar to that of more conventional insulin-sensitive tissues e.g., liver, adipocyte. After 89% of T cells from spleens on day 7 were lysed with anti-thy 1.1 antibody and complement, the ability to measure specific insulin binding was lost. These data confirm a physiologic role for insulin in T-lymphocyte effector function and describe the emergence of insulin receptors concomitant with cell sensitivity to ligand. Such receptors may play a role in hormonal modulation of the immune response.
A rapid, sensitive, and reproducible assay to determine the adhesion of platelets to collagen has been developed. Collagen fibers and adherent platelets are retained on polycarbonate membrane filters. Chemical modification of collagen by acetylation and of platelets by treatment with chymotrypsin markedly reduces adhesion. The role of fibronectin in the collagen-platelet interaction has been examined. Treatment of platelets with purified antibody or Fab' fragments to fibronectin only slightly reduces adhesion. Preincubation of platelets with high concentrations of gelatin reduces adhesion by only 22% but fails to inhibit aggregation. Thus, fibronectin has only a limited role in the adhesion of platelets to collagen and is either not involved in the adhesion that leads to aggregation or is only one of several adhesion mechanisms, any of which alone can initiate aggregation.
A radioimmunometric antibody-binding assay was developed with the use of 125I-labeled protein A of Staphylococcus aureus (SpA) for the evaluation of xenoantisera to human melanoma-associated antigens. Antisera were produced in New Zealand male albino rabbits by the injection of cultured human melanoma cells or soluble, partially purified melanoma-associated antigens isolated from these cells. Xenoantisera were rendered operationally specific for melanoma-associated antigens by absorption with human red cells and cultured lymphoblasts. The methodologic parameters and the quantitative relationships among xenoantisera, cultured melanoma target cells, and 125I-labeled SpA and their effect on the measurement of xenoantibody binding were critically evaluated. Data indicated the usefulness of the radioimmunometric assay in monitoring the efficacy of absorption and in characterizing the specificity of xenoantisera to melanoma-associated antigens. The radioimmunometric binding assay when modified and used as a binding inhibition assay was effective in the assessment of the serologic activity of soluble melanoma-associated antigens and thus may be used to monitor the progress of antigen purification.
The interactions between the bilaterally distributed components of the circadin system that controls the locomotor activity rhythm of the cockroach Leucophaea maderae were investigated in a series of surgical lesion experiments. Complete excision of one optic lobe (either right or left) or its surgical isolation from the central nervous system had no effect on the animals' ability to free-run in constant darkness nor was there any indication, as judged by postoperative pi values of any difference between left and right lobe pacemakers. However, these surgical procedures consistently resulted in a significant increase in tau over preoperative value while optic nerve section had no effect on tau. The propostion is developed that the left and right pacemakers in the two optic lobes are mutally coupled and that the compound pacemaker's period is shorter than either of its constituent pacemakers. It was also found that the integrity of either compound eye is sufficient to assure entrainment of both left and right pacemakers.
The ability of adrenocorticotrophic hormone (ACTH) to induce lung maturation was evaluated in fetal lambs. One member of 14 twin pairs between 114 and 138 days of gestation was infused intravenously with 0.5 mg ACTH over 5 days. The lungs of treated versus control lambs were judged more mature by morphologic criteria by the use of light and electron microscopy and by biochemical criteria by the use of lamellar-body-rich cell fractions. None of 5 premature lambs treated with ACTH and allowed to breathe showed evidence of hyaline membrane disease, while 3 untreated control lambs showed typical hyaline membranes.