THE ELASTIC LIMITS OF PLASMA GELS

¹ From the Biological Laboratories of E. R. Squibb & Sons, New Brunswick, New Jersey

1. A method for determination of the elastic limit (E-L) of a plasma gel has been described.

2. The effect upon E-L of dilution of plasma with serum, normal saline and distilled water has been studied.

3. A leucocytic exudation, induced in a horse by intrapleural injection of sterile aleuronat suspension, is accompanied by a marked increase in plasma E-L. The possible diagnostic value of this finding is being studied by a micro-method which permits E-L tests to be made on single drops of blood.

4. Addition of 0.2 per cent of neoarsphenamine to normal horse plasma lowers its E-L about 80 per cent.

5. The E-L effect of a given concentration of neoarsphenamine is a function of the fibrinogen content of the plasma.

6. The effect of neoarsphenamine upon plasma E-L is reduced by exposure to air or oxygen or by treatment with hydrogen peroxide. Within the ranges of oxidation studied the relation between time of exposure of a neoarsphenamine to molecular oxygen and the E-L effect of the product is described by an ogive. It is suggested that the particles of dissolved neoarsphenamine exhibit a normal frequency distribution of avidities for molecular oxygen.

7. Within certain oxidation limits the relation between the dose of hydrogen peroxide, per unit weight of neoarsphenamine, and the E-L effect is described substantially by a straight line.

8. When neoarsphenamine is oxidized to various levels, the mean lethal doses for rats, obtained by slow intravenous injection until death, exhibit a high degree of negative correlation with E-L values of the same preparations; that is, the greater the acute toxicity of an oxidized neoarsphenamine the higher is its E-L value. The same type of correlation with E-L values also is seen when the toxicity is measured by the mean survival time of rats after intravenous injection of a fixed dose of the oxidized neoarsphenamine.

9. A reduction in the acute toxicity, as well as in the E-L value, of an oxidized neoarsphenamine can be obtained by ageing its solution out of contact with air. Probably neoarsphenamine is reformed by the interaction of sodium formaldehydesulfoxylate with arsenoxide. No significant change in toxicity or in E-L value results from similar ageing of an unoxidized neoarsphenamine solution.

10. The effect of arsenoxide upon plasma E-L is only a fraction of that produced by neoarsphenamine.

11. Anoxic ageing of an alkaline solution containing equal weights of arsenoxide HCl and sodium formaldehydesulfoxylate results in a lowering of E-L value similar to that observed after ageing of an oxidized neoarsphenamine solution.

Studies of protoplasm poisoning in vitro, by means of the E-L test, are in progress.