Effects of low-level radiation upon the hematopoietic steam cell: implications for leukemogenesis

These studies have addressed firstly the effect of single small doses of x-ray upon murine hematopoietic stem cells to obtain a better estimate of the D/sub q/. It is small, of the order of 20 rads. Secondly, a dose fractionation schedule tht does not kill or perturb the kinetics of hemopoietic cell proliferation was sought in order to investigate the leukemogenic potential of low level radiation upon an unperturbed hemopoietic system. The studies reported herein show tht 1.25 rads every other day decrease the CFU-S content of bone marrow by the time 40 rads are accumulated. Studies on the effect of 0.5, 1.0, 2.0, and 3.0 rads 3 times per week are under way. Two rads 3 times per week produced a modest decrease in CFU-S content of bone marrow after an accumulation of 68 rads. With 3.0 rads 3 times per week an accumulation of 102 rads produces a significant decrease in CFU-S content of bone marrow. Dose fractionation at 0.5 and 1.0 rad 3 times per week has not produced a CFU-S depression after accumulation of 17 and 34 rads. Radiation leukemogenesis studies published to date have utilized single doses and chronic exposure schedules that probably have significantly perturbed the kinetics of hematopoietic stem cells. Whether radiation will produce leukemia in animal models with dose schedules that do not perturb kinetics of hematopoietic stem cells remains to be seen

Physical Electronics

Contains reports on three research projects

An HSEF for murine myeloid leukemia

In the past decade, a large amount of effort has gone into the development of hit size effectiveness functions (HSEFs), with the ultimate aim of replacing the present absorbed dose-RBE-Q system. However, the absorbed dose determined at the tissue level is incapable of providing information on single hits on (doses to) the single cell. As a result, it is necessary to resort to microdosimetry, which is capable of providing not only the number of hits on cells, but the distribution of hit sizes as well. From this information, an HSEF can be derived. However, to date there have been no sets of data available on animals exposed to radiations of several qualities, and for which microdosimetric data were available. The objective of the present set of experiments was to remedy this situation. Large numbers of mice were exposed to radiations of several different qualities, and were observed throughout their entire lifespan for the appearance of myeloid leukemia. The HSEF developed for this neoplasm is presented and discussed

Problems relating to flax retting and fiber quality : final report on state project no. 83

Published March 1955. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Preservation of cherries with sulphur dioxide

Published August 1939. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

A method for testing moisture in dried prunes

Published June 1927. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

A chemical study of legumes and other forage crops of western Oregon

Published July 1923. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo