Burnham S. Walker

The proteolytic enzymes of Proteus vulgaris

The production and purification of the proteolytic enzymes of Proteus vulgaris are discussed. A preparation containing two proteolytic enzymes and an inactive component was obtained. The active fraction consists of a relatively heat-stable enzyme and a heat-labile enzyme. The kinetics of these two enzmes is reported.

Nucleoprotein Content During the Staphylococcal Growth Cycle.

Summary The concentrations of pentosenucleic acid and desoxypentosenucleie acid per total nitrogen content at significant stages in the growth cycle of Staphylococcus aureus were determined. The concentrations were equal in resting or decay cultures, rose to a peak at 1-1½ hours of growth and thereafter declined. At peak concentrations, the PNA content was about twice that of DNA.

Colorimetric determination of urethane as ethyl alcohol in blood.

Summary A colorimetric method is described for the determination of urethane in blood, which gives 99 to 111% recoveries in the range 4 to 44 mg % urethane, and a nonspecific “urethane” value of normal blood of 0.1-1.4 mg %. A part of the method may be directly used for the determination of ethyl alcohol.

Some Factors Governing Renal Function.

With the ultimate objective of finding a satisfactory method for the quantitative demonstration of impairment of renal function in humans, the authors have studied the rate of elimination of urea, as compared with the amount of urea in the blood and with the simultaneous excretion of water. The previous work of Ambard, 1 McLean, 2 and Addis, 3 and of the associates and critics of these experimenters, has been considered in detail. In regard to the relationship of blood urea levels to rate of urea excretion, it will be recalled that there are two divergent schools of thought. The older group, of which Ambard and McLean are the outstanding examples, have shown that the rate of excretion is a parabolic function of the concentration of urea in the blood, according to the equation Ur = K√D. Ur = Gm. urea per liter blood. D = Gm. urea per 24 hr. (Measured over a short period and extrapolated for the 24 hours.) Addis, and later Adolph, 4 on the other hand, under conditions involving a large provocative ingestion of either urea of water, or both, have demonstrated a linear relationship, Ur = KD. Under ordinary conditions, however, the relationship approaches, but does not equal, the parabolic relationship proposed by Ambard. By combining our own data with the normal cases reported by McLean and by Addis (excluding the cases where provocative doses had been given) we were able to calculate this relationship in 220 normal individuals. By simultaneous determination of the Pearson correlation coefficient, the correlation ratios and comparison of these with each other and with the probable error, according to the method of Blakeman, 5 it was possible to demonstrate that the relationship in these normal cases was not linear.

Estimation of Small Traces of Alkaloids

The need to measure the amount of cocaine penetrating to the aqueous humor of an experimental animal after instillation of a cocaine solution into the conjunctival sac led to the following analytical procedure, which we find applicable to the quantitation of traces of many alkaloids in aqueous solution, and of certain alkaloids, particularly cocaine and strychnine, in body fluids. The method, which is accurate within the limits of colorimetric observations, is strikingly simple, and we believe will be of interest to workers in pharmacology, toxicology and experimental medicine. A. Procedure for aqueous solutions. To a measured amount of solution containing from .5 to .05 mg. of the alkaloid is added 1 cc. of a 1% solution of phosphomolybdic acid in normal sulphuric acid. This is best done in a small test tube of about 5 cc. capacity. After mixing and standing for 15 minutes, the mixture in the test tube is centrifuged and the supernatant fluid decanted. The residue is resuspended in water, again centrifuged and the supernatant discarded. To the washed precipitate is now added 1 cc. of fifth normal sulphuric acid, 1 cc. of 2% aqueous solution of hydroquinone, and after shaking, 1 cc. of the carbonate-sulphite solution used in the Bell and Doisy 1 method for phosphate determination (15% sodium carbonate and 3% sodium sulphite). The color developed is read promptly in the small Duboscq type colorimeter against a standard prepared by treating 1 cc. of a solution of known and approximately equal alkaloid content (using the same alkaloid that is being determined) simultaneously with the same reagents. If necessary, it is a relatively simple matter to prepare several standards (5 of the small test tubes can be spun in an ordinary 50 cc. metal centrifuge cup) and the proper one can be selected by inspection.