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

THE STUDY OF MENSTRUAL AND OTHER BLOOD LOSS, AND CONSEQUENT IRON DEFICIENCY BY Fesup59sup 59 WHOLE BODY COUNTING

An established method for determining radioiron absorption by whole body counting was used to study six parous women with hypochromic anemia and menorrhagia, and a seventh nulliparous woman with normal blood values and normal menses. In addition to demonstrating iron deficiency by increased radioiron absorption, the method was found useful in estimating the quantity of blood lost with each menstrual period. As much as 550 ml of menstrual loss was noted in two of the patients studied. Estimates in the patient with normal menses were 59 and 33 ml. Two additional patients demonstrated patierns of blood loss found in continuous gastrointestinal hemorrhage due to hereditary hemorrhagic telangiectasia, and in severe epistaxis, as further applications of the technique. Where available, the method is to be recommended for routine investigation of hypochromic anemia when episodic or continuous blood loss such as that of menorrhagia is suspected. (auth