In vitro combination chemotherapy demonstrating potentiation of vincristine cytotoxicity by prednisolone

Human lymphoid cells grown in long-term tissue culture have been used to study the cytotoxic effects of the combination of vincristine and prednisolone. The potentiating effects of this drug combination in vitro cannot be consistently shown if the drugs are addeded without attention to the growth rate of the cultured population. If the cultured cells have achieved maximum density and have remained at this density for more than 24hr, they are readily killed by vincristine alone and no further kill is achieved by adding prednisolone. Rapidly growing cell cultures, however, are relatively ristant to vincristine. The addition of prednisolone to such cultures restores their sensitivity to vincriestine, but the combination is no more effective than is vincristine alone in stable cell populations. These findings indicate that the effects of vincristine on the mitotic spindle, which produce metaphase arrest, do not account entirely for its ability to destroy cells. A second mechanism of action of vincristine at low concentrations is proposed.

Evaluation of four slide test kits for the detection of human chorionic gonadotropin in urine

Three "indirect-type" slide tests utilizing the principle of hemagglutination inhibition and one new "direct-type" slide test employing direct agglutination were evaluated for their sensitivity in detecting human chorionic gonadotropin (HCG) in urine. The results of positive tests in a group of woman in very early pregnancy were correlated with the "days after last menses". In this series the direct slide test was the most accurate. A control must be used with each direct test to indicate interfering substances and when such are present a different test must be used. All tests were found to be of the relative sensitivity stated by the manufacturer.

Hemostatic defects in experimental leukemia

Hemostatic defects in rats of the inbred strain BDIX suffering from transplanted acute leukemia (L 5222) are described. Prolongations of the clotting time, reduction of thrombus solidity, decrease in peripheral platelet counts and factor XIII activity, as well as defects in the extrinsic and intrinsic pathway of coagulation indicate occurrence of a hemorrhagic tendency in the course of the disease. On the other hand, there is a significant increase of fibrinogen and antithrombin III. The value of the animal model as a useful tool in investigating yet unsolved hemostatic problems in human acute leukemia is discussed.