Influence of Age on Leukemia Mortality Associated with Exposure to γ rays and 2-MeV Fast Neutrons in Male C3H Mice.

The relative biological effectiveness (RBE) of densely ionizing radiation can depend on the biological context. From a radiological perspective, age is an important factor affecting health risks of radiation exposure, but little is known about the modifying impact of age on the effects of densely ionizing radiation. Herein, we addressed the influence of age on leukemogenesis induced by accelerator-generated fast neutrons (mean energy, ∼2 MeV).

Two Cases of Metastatic Parathyroid Carcinoma in Male C3H Mice Following Irradiation.

White nodules were observed in the thyroid in two male C3H mice (at 99 and 122 weeks of age) exposed to fast neutrons at the age of 8 weeks. Histopathologically, in both cases, tumors were developed in the region corresponding to the parathyroid gland, and the tumor cells were arranged in a solid sheet or nest-like structures. Necrosis, cell debris and/or hemorrhage were sometimes seen in the center of the tumor structures.

Neurobehavioral changes in mice exposed to fast neutrons in utero.

Epidemiological studies have revealed that radiation causes brain development abnormalities in atomic bomb survivors exposed in utero. Rat and mouse studies have also shown that prenatal exposure to low-linear energy transfer radiation induces developmental brain anomalies. Because the effects of prenatal irradiation on adult behavior patterns remain largely unknown, the present study investigated the effects of neutron exposure in utero on postnatal behavior patterns in mice.

Existence of a threshold-like dose for gamma-ray induction of thymic lymphomas and no susceptibility to radiation-induced solid tumors in SCID mice.

Severe combined immune deficiency (SCID) mice exhibit limited repair of DNA double-strand breaks and are sensitive to ionizing radiation due to a mutation of the DNA-dependent protein kinase catalytic subunit gene. To elucidate the effects of deficient DNA double-strand break repair on radiation-induced carcinogenesis, the dose-response relationship for the induction of all tumor types was examined in wild-type and SCID mice. In wild-type mice, the incidence of thymic lymphomas at gamma-ray doses up to 1 Gy was almost equal to the background level, increased gradually above 1 Gy, and reached a maximum of 12.

Investigation of new cytogenetic biomarkers specific to high-LET radiation using in vivo and in vitro exposed human lymphocytes.

Purpose: To find detectable cytogenetic biomarkers that can offer information about the radiation quality of in vivo exposure retrospectively.

Materials And Methods: Chromosome-type aberrations of peripheral lymphocytes of uterine cancer patients that received internal gamma- and external X-ray therapy or carbon beam therapy and of victims severely exposed to neutrons and gamma-rays in a criticality accident that occurred in Tokai-mura, Japan were analysed. Data obtained from in vitro irradiation experiments using 60Co gamma-rays and 10 MeV neutrons were compared with the in vivo exposure data.