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Rabbit weighing 2 4209 Curve I 60 120 I80 240 min 209 I , 1 I -I I 1 60 120 Id0 240 NO 360min."i F I G . 1. Effects of injections of dibciiamin before and after the administration of tuvphoid endotoxin Cnrrc 1-Skin temperature after a n intravenous injection of typhoid endotoxin (1 m.1.d.). Curve ?-Effect of an injection of dibeiianlin before the administration of the toxin. Curve 3-Eff ect of a11 injection of dihriianiin after the administration of the toxin. Curve 4-Effect of 2 iii,jectioiis of dihcnamin, one hefore and one after the administration I n the 4 curves, the iiiteriial t e i i i p e i~i t u i~ is indic.ated by a dotted line.(in the skin temperaturc of the rabbit's cay.of the toxin (the left ear has heen dicnerrated four days before the experiment).can be decreased by previous administration stances, bringing about peripheral vasoconof Dibenamin. However, to maintain this striction. Dibenamh, a sympatho-adrenal effect. it is necessary to follow with another blocking substance, antagonizes ithis ,effect. injection of Dibenamin (3 mg per kg) (Curve ' FWe are indebted to Dr. E. R. Clark for his interest 4 ) .Summary and conclusions. The injection and continuous advices in our investigation. S. typhosa endotoxin appears to stimulate the liberation of adrenalin or adrenalin-like sub-Sutritional differences among sucrose, dextrin, lactose, and cerelose have been reported viewed much of the work done on carbo-by several workers. Elvehjem( 1 J ) has re-Solvents Corporation, Terre Haute, Indiana; by _.

Preparations of rat liver have been shown to possess a nicotinamide mononucleotide: pyrophosphate phosphoribosyl transferase (EC 2.4.2.12) which specifically requiresadenosine triphosphate, as well as 5phosphoribosyl 1-pyrophosphate: These same preparations will synthesize nicotinamide mononucleotide in the absence of adenosine triphosphate if the concentration of both 5-phosphoribosyl I-pyrophosphate and magnesium is greatly increased. Similar heat labilities, identical gel electrophoretic patterns, and molecular weights indicate that nicotinamide mononucleotide synthesis stimulated by adenosine triphosphate or high levels of 5-phosphoribosyl 1-pyrophosphate and magnesium is probably catalyzed by the same enzyme. These data, together with an analysis of the kinetics of R at liver NMN pyrophosphorylase requires ATP as well as nicotinamide and PRPP (Dietrich et al., 1966), and is markedly inhibited by physiological levels of NAD (Dietrich and Muniz, 1966). The enzyme fraction which synthesizes N M N in the presence of ATP will also form N M N in the absence of ATP if the levels of both PRPP and magnesium are greatly increased (Powanda et a[., 1968). In addition, the activity of this enzyme is decreased some 40z by adrenalectomy or hypophysectomy (Dietrich et a/., 1967). These data suggested that nicotinamide mononucleotide pyrophosphorylase is a likely point of control in pyridine nucleotide metabolism and that ATP may be a positive