Radiation carcinogenesis of the rat mammary gland was investigated with the objective of investigating the combined effect of oestrogen administration and irradiation. Three rat strains, Sprague-Dawley, Wistar WAG/Rij and Brown Norway, with different susceptibilities to the induction of mammary cancer, have been irradiated with X-rays and mono-energetic neutrons. Increased hormone levels were obtained by subcutaneous implantation of pellets with oestradiol-17 beta (E2). The tumour incidence results were corrected for competing risks and were analysed with a continuous failure time distribution. The latency period for the hormone-treated animals is considerably shorter than for animals with normal endocrinological levels. Administration of the hormone results in an appreciable increase in the proportion of rats with malignant tumours. At the level of hormone administration applied in this study, radiation and hormones appear to produce an additive effect. The effect of hormone administration and irradiation for mammary tumourigenesis is equal for hormone administration one week prior to, or 12 weeks after irradiation. The RBE values for induction of mammary carcinomas after irradiation with 0.5 MeV neutrons have a maximum value of 20 and are not strongly dependent on the hormone levels.
Graft-versus-host disease (GvHD) after bone-marrow transplantation in dogs is controlled by many different genetic systems. In littermate combinations identical for the major histocompatibility complex (MHC) the number of systems that influence GvHD is related to the number of donor lymphocytes injected. If the number of donor lymphocytes administered is sufficiently low, minor histocompatibility systems do not influence survival after bone-marrow transplantation. With increasing numbers of donor lymphocytes the beneficial influence of MHC matching on GvH incidence and severity disappears and minor histocompatibility antigens, coded for on at least two other autosomal chromosomes as well as possibly the Y chromosome, can cause severe GvHD. In contrast, the X chromosome does not appear to carry a histocompatibility system that is of relevance to GvHD control. The severity and tissue distribution of histological signs of GvHD in recipients of bone-marrow and lymph-node cells from MHC-identical donors are similar to those in recipients of MHC-mismatched bone-marrow cells. Female donors do appear to cause severe GvHD more frequently than males. In contrast to rhesus monkey and human bone-marrow cells, dog bone-marrow cells are negative in PHA tests. This is in accordance with the generally benign course of GvHD in dogs that are treated with bone-marrow cells only from histocompatible littermate donors. The influence of the sex of the bone-marrow donor on GvHD incidence and severity is not reflected in differences between PHA tests with male and female dog lymphocytes. A better predictive test for GvH potential than the PHA test appears to be needed. Alternatives to additional donor selection for the prevention of GvHD in histocompatible recipients appear to be the use of a male donor and the removal of lymphocytes from bone-marrow-cell suspensions prior to transplantation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.