Effects of B Vitamins and Liver on Growth of Immature Rats Maintained at Low Temperatures.

Abstract

226COLD ASD VITXMIPU' BI2 REQUIREMEST linear function. We attribute this to an obscure factor ( s ) which in some manner probably interferes with the activity of Ac-globulin. Our data suggest that this factor may he fibrinogen concentration. In a previous publication(7) and in quantitative data to be published, the importance of fibrinogen on .\c-globulin activity has been stressed. Jn constructing the reference curves from the normal control plasmas. it was observed that the niaxiniuni deviation of areas as well as the variation of slopes became progressively less as the accurate volume range was approached. ';\.Ioreover, the maximum deviation of areas and slopes was decidedly less with defibrinated than with undefibrinated plasma. M'hen 1 to 5 x ml of human plasma were used, the slopes of the lines derived from undefibrinated plasma were consistently less than those from defibrinated plasma. -As the volume of plasma was increased to the accurate range, the slopes of the undefibrinated and of the defihrinated plasma approximated each other. Thus, the observations would indicate that fibrinogen alters the ;\c-globulin activity and therefore the slopes of the reference curves! and that Ac-globulin assays can be done more ac-7 . Carter, J. R., and Warner, E. D., PRor. SOC. ESP. BIOL. AXD MED., 19.50. v74, 388.curately on defibrinated plasma.i7ariables, such as temperature, reactivity of the biologic reagents etc. which affect other assay methods in blood coagulation, likewise exert their influence on the assay of Ac-globulin activity. The influence of these variables is manifested as a shift in intercept of the reference control curves from day to day. These variables do not alter significantly the slope of the reference curves. The existence of such variables, however, does demand that the intercept be established each day by the assay of ,\c-globulin activity on normal control plasma.I n the assay of Ac-globulin activity, the prothrombin concentration is adjusted so that 2 units rather than 1 unit are present in the clotting tube. -4s a result, a smaller volume of plasma is required for the estimation of Xc-globulin activity, and the effect of antithrombin on the conversion rate and thrombin yield is correspondingly decreased.Summary. A method for the quantitative estimation of Ac-globulin in plasma has been described. The method is based upon the use of three variables-onversion rate, thrombin yield, and onset of thrombin formation. K i t h the use of all three variables combined, a greater degree of accuracy can be obtained.