Walter A. Rambach

Acid Hydrolysis of Erythropoietin.

Summary Purified erythropoietin has been subjected to mild acid hydrolysis. This mucoprotein thus has been further characterized and shown to lose erythropoietic activity upon hydrolytic removal of neuraminic acid.

Purification of Erythropoietin by Ion-Exchange Chromatography

Summary A method for purification of erythropoietin from the filtrate of acidified, boiled plasma prepared from phenylhydrazine anemic rabbits utilizing DEAE-cellulose ionexchange columns has been described. The active erythropoietic factor thus prepared has been partially characterized and shown to be a low molecular weight, acidic glycoprotein.

Protective Effect of Hypoxia against Irradiation Injury of the Rat Bone Marrow and Spleen.

Summary 1. Rats irradiated in a hypoxic atmosphere show a slightly higher cellularity and much greater rate of DNA synthesis in the bone marrow and spleen after 96 hours than rats irradiated at ground level. 2. Thirty hours of intermittent hypoxia preceding irradiation at low oxygen tensions does not give additional protection. 3. A striking parallelism exists in the cellular reactions in the bone marrow and spleen following irradiation, both at normal atmospheric pressures and at low oxygen pressure. 4. Irradiation of animals at low oxygen pressures appears to reduce the biological effectiveness of 800 r on the bone marrow to 600 r.

Erythropoietic Activity of Tissue Homogenates.

Summary Homogenates of rat liver, kidney, brain, spleen and muscle prepared in modified Tyrodes solution and injected into the rat are capable of stimulating erythropoiesis as measured by Fe59 incorporation into red cells and reticulocyte counts. The activity of the homogenates does not appear to be a nonspecific effect. Certain points of similarity are noted between the homogenates and plasma erythropoietin.

Nucleic acid metabolism of bone marrow and spleen. I. Normal values and effect of sodium pentobarbital.

Summary (1) Normal values are presented for the desoxyribose nucleic acid phosphorus and ribose nucleic acid phosphorus as well as the rate of uptake of P32 by the DNA and RNA in the bone marrow and spleen of adult rats. (2) Anesthetic doses of sodium pentobarbital were found to produce a significant decrease in the relative rate of formation of DNA in the bone marrow and spleen during a period of 5 1/2 hours. (3) The significance of these observations is discussed.