Plasma 11-Hydroxycorticoid Levels after Carbenoxolone Sodium

A definite rise in plasma 11-hydroxycorticoid levels has been shown in eight patients with duodenal ulcer following the oral administration of carbenoxolone sodium. A similar rise was seen in one patient with sarcoidosis whose pituitary A.C.T.H. secretion had been acutely suppressed with dexamethasone. No such rise, however, was seen in three patients suffering from adrenal insufficiency. It is suggested that carbenoxolone acts directly on the adrenal cortex, causing an increased production of corticosteroids.     

The Contractile and Control Sites of Natural Actomyosin

The various contractile and control sites of natural actomyosin gel were studied by comparing the kinetics of ATP hydrolysis with those of gel contraction, measured as an increase in turbidity. Contraction of actomyosin gel seems to require the cooperative reaction of ATP (with Mg) at two different sites. One of these sites catalyzes the hydrolysis of ATP and most probably contributes the driving force for contraction; the binding of ATP to the other site appears to break certain links that retard movement of the gel components. At limiting concentrations of ATP, the rate of contraction seems to depend on the rate of breaking these links as well as on the rate of ATP hydrolysis. But when both sites are saturated, the rate of contraction appears to be limited only by the rate of ATP hydrolysis. In addition to these two contractile sites, there are also two different control sites. At one, the relaxing site, the binding of ATP with Mg inhibits ATP hydrolysis and gel contraction. At the other, the binding of calcium activates contraction by overcoming the inhibitory action of Mg and ATP at the relaxing site. This control system—inhibition by substrate and disinhibition by calcium—can be selectively inactivated by heat and reactivated by dithiothreitol, a disulfide-reducing agent. These observations on the isolated contractile system are discussed in relation to the contraction and relaxation of muscle.     

METHOD FOR COMBINED ULTRASTRUCTURAL AND BIOCHEMICAL ANALYSIS OF NEURAL TISSUE

No significant change was found in the electrolytes and lipids of the brain analyzed after glutaraldehyde fixation by perfusion of laboratory animals; such fixation also satisfactorily preserves neural tissues for electron microscopy. The brains of normal and tumor-bearing C3H mice, Wistar rats, and New Zealand rabbits were studied. Little difference was found in the dry weight and the content of sodium, potassium, total lipid and lipid fractions, and in the sulfate space (S³⁵O₄) between specimens from unperfused and perfused animals, whether normal or tumor-bearing. The results suggest the possibility of using selected regions of the nervous system, dissected after fixation, for chemical study and at the same time characterizing similar regions morphologically with the electron microscope.     

Production of 2-Ketogluconic Acid by Serratia marcescens

Production of 2-ketogluconic acid from glucose by fermentation with Serratia marcescens NRRL B-486 was studied in 20-liter stainless-steel fermentors. Conditions for 2-ketogluconic acid production included the following: glucose-salt medium, aeration rate of 0.75 volumes per volume per minute, agitation rate of 400 rev/min, temperature of 30 C, CaCO₃ to neutralize the acid formed, and a 5% (v/v) inoculum. Foaming was controlled with an antifoam agent added at intervals during the fermentation. When 120 g per liter of glucose were supplied, 95 to 100% yields of 2-ketogluconic acid were obtained in 16 hr. Larger amounts of glucose could be used in the fermentation provided that the carbohydrate was fed continuously. Continuous feeding of glucose to a total amount of 180 g per liter gave 95 to 100% yields of 2-ketogluconic acid in 24 hr; feeding glucose to a total amount of 240 g per liter gave 85 to 90% yields in 32 to 40 hr.