Search

The kinetics of inhibition of 5'-adenylic acid deaminase and creatine-ATP transphosphorylase by their respective antibodies are studied and rate constants of combination are ascertained. It is shown that the single substrate 5'-adenylic acid (AMP) of deaminase "protects" the enzyme against antibody inhibition. However, phosphate, a competitive inhibitor of the highly specific deaminase, enhances combination with antibody. With creatine kinase, however, addition of either of the substrates, alone or in combination with the required magnesium, each of which separately bind to the enzyme, does not prevent inhibition of the enzyme by its antibody. However, the "working" enzyme combined with all substrates is "protected" against antibody inhibition.

A specific and characteristic type of anemia is not a feature of all malignant disease. To the contrary, the nature of the anemia will depend upon the causative mechanism, of which blood loss and accelerated erythrocyte removal appear to be the most frequently seen and the most clearly defined. Recognition of anemia due to loss of blood is relatively simple if the subtlety of blood loss in the stool is borne in mind and persistent testing to demonstrate it is carried out. Indeed, anemia characterized by chronic loss of blood in men can only mean chronic gastrointestinal bleeding if certain rare hemoglobin abnormalities can be ruled out. Anemia due to accelerated erythrocyte removal may also be recognized by simple measures. After transfusions raise hemoglobin values to near normal levels, the disappearance of the transfused blood and the rapid return of the pretransfusion severity of anemia are good evidence of the presence of such a mechanism, if blood loss can be ruled out.Adequate management of the anemia of malignant disease depends upon a clear understanding of the various mechanisms involved. It is highly probable that attention to this feature will, in many instances, significantly prolong the productive life of persons with malignant disease.