The uptake of S35 from methionine by plasma proteins in proteindepleted and tumor-bearing dogs.

One of the most important problems in nutrition today is the determination of the degree of de pletion in tissue proteins associated with malnu trition and with disease. Various biochemical measurements have been developed to estimate the degree of depletion, such as the reduction of plasma albumin or of the albumin/globulin ratio, changes in the activities of certain enzyme sys tems, and alterations in nitrogen balance (3). None of these measurements, however, correlates perfectly with the degree of depletion in all physi ological states (2). One common factor associated with depletion is an altered protein metabolism which is reflected by an increased nitrogen reten tion and utilization of certain amino acids. The uptake, for example, of S36-labeledmethionine by