Combination Of Gamma Irradiation Research Articles

Molecular signals in antigen presentation. II. Activation of cytolytic cells in vitro after ultraviolet radiation or combined gamma and ultraviolet radiation treatment of antigen-presenting cells.

Murine low-density spleen cells have potent antigen-presenting ability in a hapten-specific cytolytic T lymphocyte (CTL) system using the hapten azobenzenearsonate (ABA). Exposure of these cells to 0.33 KJ/m2 of ultraviolet radiation (UVR) after coupling to hapten results in markedly inhibited antigen-presenting function that can be substantially corrected or bypassed by interleukin 1 (IL 1). These results have been interpreted to reflect an inhibition of Lyt-1+ T cell activation by UVR-treated APC. Treatment of these cells sequentially with 1500 rad of gamma-radiation (GR) prior to hapten coupling, followed by 0.33 KJ/m2 of UVR radiation after coupling, results in an antigen-presenting defect only minimally improved by IL 1. However, partially purified interleukin 2 (IL 2) can completely bypass or correct this defect. Thus, combined GR and UVR induces a different or more profound defect in APC function when compared to UVR alone. However, these cells do provide a signal(s) other than hapten necessary for CTL activation because ABA-coupled high density spleen cells do not activate CTL cells, even with the addition of IL 2. Fluorescence-activated cell sorter analysis demonstrates that exposure of these low density spleen cells to GR or UVR results in decreased I-A antigen expression at 24 hr than either alone. The addition of nonhapten-coupled low-density APC partially reconstitutes the ability of combined GR/UVR-treated LD-APC to present antigen, and this effect is enhanced by the administration of exogenous IL 1. This occurs despite a lack of significant accessory cell activity by the LD-APC for the ABA hapten, and indicates that combined GR/UVR-treatment of APC is not functionally equivalent to completely removing them.

Effect of Gamma Irradiation, Penicillin, and/or Pectic Enzyme on Chick Growth Depression and Fecal Stickiness Caused by Rye, Citrus Pectin, and Guar Gum

The effects of gamma irradiation of rye, corn, pectin, and guar gum and supplementation of procaine penicillin and/or pectic enzyme (Irgazyme-100) were studied. Addition of 62.5% rye, 4% pectin, or 2% guar gum in place of corn significantly reduced chick growth (P<.05). Exposure to gamma irradiation, procaine penicillin, or pectic enzyme supplementation improved the growth of chicks fed rye. Growth response on the rye diet to one or more combinations of gamma irradiation, procaine penicillin, and pectic enzyme was greater than that of gamma irradiation, procaine penicillin, or pectic enzyme alone. Gamma irradiation or pectic enzyme supplementation of pectin or guar gum improved chick growth and almost eliminated their growth depressing properties. A combination of gamma irradiation and pectic enzyme failed to give a further significant increase in growth over that of either alone. Addition of procaine penicillin to diets containing rye, irradiated pectin, or guar gum elicited a significant growth response, but the response was greatly reduced when diets contained irradiated guar gum or irradiated pectin.Feces of chicks fed diets containing rye, pectin, or guar gum adhered to screen floors in much greater amounts than for corn-fed chicks. Gamma irradiation, procaine penicillin, or pectic enzyme had no significant effect on fecal condition of birds fed diets containing rye or guar gum. In contrast, fecal condition of birds fed guar gum was significantly improved by a combination of gamma irradiation and pectic enzyme supplement. Gamma irradiation almost eliminated and pectic enzyme supplementation completely eliminated properties of pectin causing sticky feces. Results indicate that the component of rye that causes sticky feces was not changed by gamma irradiation and/or pectic enzyme, and, therefore, is different from the growth depressing factor and from citrus pectin.

Effects of Simulated Fallout Radiation on Iron Kinetics, Red Cell Mass, and Plasma Copper in Sheep

Iron kinetics, red cell mass, and plasma copper were measured in sheep subjected to various combinations of gamma irradiation of the total body and beta irradiation of the skin and gastrointestinal tract. Beta irradiation of the skin, and to a lesser extent of the gastrointestinal tract, produced hypoferremia, a decrease in circulating red cell mass, and hypercupremia. Changes in iron kinetics indicated an increased rate of erythropoiesis. It is suggested that the reduction in red cell mass is caused by an abnormally high rate of destruction of erythrocytes which are damaged as a consequence of circulating through injured tissue. The hypercupremia may be a response to the increased demand for iron necessary for hemoglobin formation.

Effects of Combined Gamma Radiation and Thermal Exposure on Some Mechanical Properties of Three Polyaromatic Yarns

Three experimental polymeric yarns, a polyimide, an aromatic polyamide, and a polybenzimidazole, were exposed to various gamma dosages up to 1.4 × 109 ergs/g carbon and exposure times up to 18.2 hr. Specimens ere exposed to the gamma radiation alone and also in combination with elevated temperatures. Temperatures of 400°, 600°, and 800°F were used in conjunction with the gamma radiation. All speci mens were evaluated for mechanical properties, i.e., tenacity, elongation, and work-to- rupture. Each polymeric yarn had higher strength, greater elongation, and better energy absorbing capability after thermal-gamma exposure. Exposure at 600°F and all radia tion dosages gave the best results for the polybenzimidazole (PBI) yarn, while exposure at 400°F and radiation dosages of 1.9 × 108 and 7.3 × 108 ergs/g carbon gave the best results for the polyimide and aromatic polyamide yarns. It can be concluded that the thermal stability of these yarns can be improved by thermal gamma treatment.

THE EFFECT OF PRETREATMENT WITH MALEIC HYDRAZIDE OF THE MUTATION RATE INDUCED BY GAMMA RADIATION IN &lt;i&gt;DROSOPHILA MELANOGASTER&lt;/i&gt;

Treatment with gamma radiation in combination with malefic hydrazide exhibit an additive effect as regards as the formation of sex-linked recessive lethal mutations, when applied to Drosophila melanogaster spermatozoa.

States inSi28with12.7&lt;Ex&lt;13.7MeV by (α,γ) and (α,α) Reactions onMg24

The radiative capture and elastic scattering of alpha particles by ${\mathrm{Mg}}^{24}$ have been studied for alpha-particle energies between 3.2 and 4.5 MeV. The yield and angular distributions of the gamma radiation in combination with a dispersion analysis of the ${\mathrm{Mg}}^{24}(\ensuremath{\alpha},\ensuremath{\alpha}){\mathrm{Mg}}^{24}$ data gave information on the resonance energies, angular momenta, parities, and some partial widths of states in ${\mathrm{Si}}^{28}$. The excitation energies and the corresponding spins and parities of the ${\mathrm{Si}}^{28}$ levels considered were: 12.74 MeV, ${2}^{+}$; 12.82 MeV, [${0}^{+}$ or ${3}^{\ensuremath{-}}$]; 12.83 MeV, ${1}^{\ensuremath{-}}$; 12.87 MeV, ${4}^{+}$; 12.92 MeV, ${2}^{+}$; 12.99 MeV, ${1}^{\ensuremath{-}}$ and ${0}^{+}$ (two levels); 13.06 MeV, ${0}^{+}$; 13.12 MeV, ${2}^{+}$; 13.19 MeV, [?]; 13.25 MeV, ${0}^{+}$; 13.27 MeV, [${1}^{\ensuremath{-}}$]; 13.38 MeV, [?]; and 13.71 MeV, ${2}^{+}$.