Whole body gamma irradiation of albino rats with sublethal doses 1.75 Gy and 3.5 Gy augmented the cholesterol level in liver and a decline in serum and aorta. Total phospholipids of liver were increased manifold, whereas, increase in aorta and serum was around 30 percent when animals were exposed to 3.5 Gy of gamma rays. Phosphatidyl choline, lysophosphatidyl choline, phosphatidyl ethanolamine and sphingomyelin followed a similar trend as total phospholipids.

View full abstract

To determine possible migratory responses to LPS of haemopoietic stem cells (CFUs) in LPS-nonresponsive (C3H/HeJ) mice, changes in the number of CFUs and granulocyte-macrophage progenitor cells (CFUc) after LPS-treatment where studied in splenectomized C3H/ HeJ mice. Splenectomy abrogated the decrease in bone marrow stem cells (CFUs and CFUc) induced by LPS in both LPS-responsive and nonresponsive mice. Recovery of bone marrow stem cells after irradiation was greatly enhanced by splenectomy in C3H/slc mice, but such enhancement was not observed in C3H/HeJ mice. These data suggest that the increase in the number of haemopoietic stem cells in the spleen in C3H/HeJ mice depends on the migration of haemopoietic stem cells from marrow to the spleen. Thus, the expansion of CFUs does not correlate with increase in the number of whole body haemopoietic stem cells. The migrationinducing activity of LPS seems to differ from its haemopoietic stimulatory activity, since the LPS-nonresponsive C3H/HeJ mice respond to the former activity of LPS.

View full abstract

The effect of a hypoxic-cell radiosensitizer misonidazole on the radiation-induced reduction of DNA bases (thymine, cytosine and adenine) was studied in deaerated aqueous solution containing sodium formate (100 mM) at pH 7.0. The reductive decomposition of DNA bases proceeded in proportion to the irradiation dose in the absence of misonidazole with G-values of 3.7 for thymine, 2.1 for cytosine and 0.5 for adenine. On irradiation in the presence of misonidazole, the induction period proportional to the initial concentration of misonidazole was observed prior to the initiation of base decomposition. A stoichiometrical investigation showed that one misonidazole molecule reacts stepwise with four electrons originated from reducing species such as e^-_aq, CO^-·₂ and base radical anions (or their protonated forms) during the course of its reduction. The four-electron reduction products of misonidazole retarded the base decomposition occurring after the induction period. The degree of the retardation increased with increasing the concentration of the four-electron reduction products of misonidazole

View full abstract

A study to elucidate the effects of atomic bomb (A-bomb) radiation exposure on the incidence of stomach cancer was conducted on 79, 856 A-bomb survivors included in the Life Span Study sample for whom dose estimates are available. From cases diagnosed during the period 1950-77 a total of 2, 155 were accepted, following review of the clinical and pathologic records, as meeting the criteria for stomach cancer. 1. Evaluation of the effects of each dose group corrected for sex and age, showed a significant increase in the risk of stomach cancer only in the heavily exposed 200+ rad group. In the 200+ rad group, the increase in stomach cancer risk was remarkable in the under 30 years of age at the time of the bomb (ATB) group. 2. The dose-response relationship of the incidence of stomach cancer as followed over a period of 27 years is not quadratic, but linear. Based on this finding, the estimated risk of A-bomb radiation-induced stomach cancer is 1.24 per 1 million person years/rad. 3. Histologically, the differentiated type is frequently observed in the control and low dose groups, and poorly differentiated type in the high dose group. 4. There is a significant difference between these histological types in the degree of intestinal epithelial metaplasia by exposure dose.

View full abstract