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A commercial reagent-impregnated paper strip test for the determination of production of niacin by mycobacteria has been evaluated. Safety, simplicity, uniformity, and stability were found to be inherent features of the test strips. Results compare favorably with those obtained using the Konno test as modified by Runyon and associates. Precautions which must be observed in performing this determination are listed.

The data presented demonstrate the potential of surfactant-fortified scintillation cocktails in overcoming many of the problems encountered in the quantitation of radioactivity on solid supports. Using a broad range of representative ionic and polar biochemical compounds, the in vial elution and quantitative recovery of 3 H and 14 C-labeled components from a wide assortment of common solid support media has been demonstrated. This methodology in combination with zero elution counting systems and in some circumstances gelled suspension counting should combine to overcome most of the problems associated with determination of isotopic activity on such solid support media.

Dogs were given infusions of norepinephrine and subsequent additional infusions of propranolol and nicotinic acid over a 4-hr period. Under different physiological conditions, alpha-lipoproteins of three different electrophoretic mobilities were identified by means of paper electrophoresis; they were designated alpha-lipoproteins X, Y, and Z. During norepinephrine infusion, alpha-lipoprotein Y fell from 45% (of all lipoproteins) to 14%. There was a reciprocal rise in alpha-lipoprotein Z. On the other hand, alpha-lipoprotein X was not significantly changed. There was evidence that alpha-lipoprotein Y was progressively transformed into alpha-lipoprotein Z by increasing plasma FFA concentrations. The percentages of both alpha-lipoproteins Y and Z returned to original values after the dogs were given either nicotinic acid or propranolol. The alterations in the alpha-lipoprotein peaks Y and Z were rapid, being noted within 5 min of change in plasma FFA concentration. However, there appeared to be a threshold of plasma FFA concentration of 1200 micro Eq/liter, below which no changes in alpha-lipoproteins were noted. It was concluded that alpha-lipoprotein Y is rapidly, progressively, but reversibly transformed into alpha-lipoprotein Z by binding to plasma FFA above a threshold level of 1200 micro Eq/liter. However, alpha-lipoprotein X does not appear to be involved in the binding of plasma FFA.