John J. Majnarich

Cell proliferation accelerating and inhibiting substances in normal and cancer blood and urine.

Conclusions 1. Blood serum and urine contain two types of substances; the one which accelerates the rate of cell prolifera- tion, and the other which inhibits the rate of cell proliferation. 2. Normal blood sera and normal and pathological urine accelerate the rate of cell proliferation in bone marrow cultures in vitro because of an excess of accelerating substances over inhibiting substances present. 3. Blood sera from neoplastic disease, pernicious anemia and leukemia inhibit cell proliferation in bone marrow cultures because of an excess of inhibiting substances over accelerating substances present. 4. Individual urine and blood serum specimens have been shown by adsorption on Norit and elution with NaOH and ammoniacal acetone to have both inhibiting and accelerating substances present.

Cell Proliferation Accelerating and Inhibiting Substances in Blood Serum During Pregnancy.

Summary 1. Two types of factors which affect cell proliferation have been observed in blood serum, one of which accelerates the rate of normal cell proliferation, and the other inhibits the proliferation of normal cells. Normal blood serum contains a predominance of factcrs which accelerate the rate of normal cell proliferation. During pregnancy there is a progressive change in the balance of factors which affect cell proliferation such that the factors which inhibit proliferation of normal cells become predominant. 2. The rate of cell proliferation of a cell suspension in vitro of cells obtained from rat embryos and fetuses, at least up to the 15th day of pregnancy, is accelerated by 2-amino-4-hydroxy-7-methyl pteridine and cancer blood serum and inhibited by xanthopterin and normal human blood serum. 3. The rate of cell proliferation of a cell suspension in vitro, of cells obtained from rat young at the time of birth, is accelerated by xanthopterin and normal human blood serum and inhibited by 2-amino-4-hydroxy-7-methyl pteridine and cancer blood serum.