Beverly Wescott Gabrio

ERYTHROCYTE METABOLISM. V. LEVELS OF GLYCOLYTIC ENZYMES AND REGULATION OF GLYCOLYSIS

In contrast to many other cell types in which a variety of metabolic pathways may contribute to energy production, the human erythrocyte derives its energy almost exclusively from the breakdown of glucose to lactate via the glycolytic sequence. Lactate can arise also from glucose by an alternate route, namely the hexose monophosphate shunt and the pentose cycle, but this latter pathway is relatively inoperative in the erythrocyte under normal conditions, owing to the unexplained preferential conversion of glucose-6-phosphate to fructose-6-phosphate, rather than to 6-phosphogluconate. The red cell, therefore, offers a unique opportunity to correlate physiological function, or malfunction, with enzymatic activity, since the number of metabolic pathways, fortunately, is somewhat restricted. In the present investigation a detailed study has been undertaken to define the optimal conditions for the conversion of glucose to lactate in the intact erythrocyte and in hemolysates. In addition, levels of the individual glycolytic enzymes have been determined and this information has been used to discuss regulatory mechanisms of glycolvsis in the ervthrocyte.

Quantitative Measurement of Hematopoietic Cells of the Marrow

In recent years with the availability of more accurate methods, attention has been directed towards the quantitative aspects of both erythropoiesis and leukopoiesis. It has been difficult to measure the precursor cells in the marrow, and their exact number still remains in question. Previous estimates of total marrow cells have utilized three general methods of approach: a) direct measurements of volume and cellularity of marrow in animals (1); b) calculations based on an assumed maturation time and on the known life span of the erythrocyte (2); and c) calculation based on the frequency and the estimated duration of marrow mitosis (3). The first of these methods imposes formidable technical difficulties and cannot be performed in man; the other two involve assumptions not subject to validation. The present report concerns a direct technique in which the various procedures and assumptions employed are scrutinized. The method employs the eythroid tag Fe59 to relate the cells in an aliquot of marrow to the total marrow, as originally proposed by Suit (4).

ERYTHROCYTE PRESERVATION. VI. THE STORAGE OF BLOOD WITH PURINE NUCLEOSIDES

The addition of adenosine to stored blood results in a chemical restoration of deteriorated erythrocytes and sustains their viability during continued storage (1, 2). This phenomenon has been referred to as the in vitro reversibility of a biochemical lesion of storage. Apart from the implications of this reaction in red cell metabolism (3), it seemed of importance to evaluate the effect of adenosine in the preservation of blood. The present study indicates that adenosine and some related purine nucleosides retard the onset of the storage lesion and extend significantly the period of viability of stored blood. The effective concentration of these supplements, as well as their potential toxicity, is discussed.