Chromosome aberrations in Crepis capillaris after gamma-irradiation and clinostatism

The rate of cell division and emergence of spontaneous and radiation chromosomal aberrations in Crepis capillaris exposed to clinostating were determined. The plants were gamma-irradiated with 300 R during clinostating when the primary roots were 1-2 mm long. The velocity of clinostat rotation was 2 rpm. The mitotic index was not affected either by clinostating alone or combined with irradiation. The exposure to clinostating did not change significantly the total frequency of nuclear aberrations or the distribution of the aberrations of the chromosomal and chromatin type as well as aberrations resulting from one or two radiation events. Thus, the effect of clinostating combined with gamma-irradiation can be considered zero.     

Synthesis of tritiated tuftsin and macrophage inhibitory tripeptide via acetylenic intermediates

Acetylenic analogues of tuftsin (Thr-Dah-Pro-Arg) and of a macrophage inhibitory tripeptide (Thr-Dah-Pro) have been synthesized by conventional procedures in solution (Dah = 2,6-diamino-4-hexynoic acid). These acetylenic derivatives are intermediates for the preparation of structurally unmodified, tritiated peptides. Catalytic tritiation of Thr-Dah-Pro-Arg and of Thr-Dah-Pro has afforded the radioactive tetra- and tripeptides with specific activities of 11.4 Ci/mmol and 37 Ci/mmol, respectively.     

Inhibition of in vitro adherence of antibody-coated red cells to monocytes by the dialyzable leukocyte extract

The red cell-monocyte assay (RMA), which has been used to evaluate the clinical significance of red cell (RBC) antibodies, was employed to test the effect of the dialyzable leukocyte extract (DLE) on in vitro adherence to monocytes of human RBCs coated with alloantibodies or autoantibodies. The total association index (TAI) of the RMA, expressing the number of RBCs adhering to or phagocytosed by 100 monocytes, indicated a potent inhibitory activity of DLE in the test system. TAI values of 100.4 +/- 20.1 (mean +/- SD) in the control sample, consisting of RBCs coated in vitro with anti-D, dropped to 4.0 +/- 2.1 when DLE was present in the assay medium at a concentration of 0.5 U per mL. Similar results were obtained with RBCs coated with IgG antibodies in vivo. The inhibition was dose dependent and was associated with a thermolabile component of DLE. This study establishes that DLE can modulate monocyte function by inhibiting the recognition of IgG sensitized red cells.