Simple flocculation test to demonstrate one aspect of the colloid-protein lability of whey

Abstract

150 tests carried out on serums of different diseases simultaneously with the cephalin-cholesterol test with concordant results permit to deduct that the “cholesterol test” depends on the qualitative and quantitative alterations of the v globuline fraction, in relation with the quantity and quality of the albumin fraction. The importance of the factor dilution of the serum (1 X 20) on the concentration of the cholesterol employed in the suspension has been shown. The proposed test has the advantages of greater simplicity and cheapness; moreover, its results are subject to less technical errors.

Reagents

Alcoholic cholesterol solution. — i g. of pure cholesterol and 3oo mi. of 96 per cent alcohol are heated in a "water bath till dissolution, or allowed to remain in the ofen at 37º C. for two days the same purpose. The addition of 0.2 mi. of a 10 per cent alcoholic solution of Victory blue for each 100 ml. of reagent meakes eassier appretiation of results.

Colloidal suspensión of cholesterol. — Put in a flask 32 mi. of neutral distilled water, and in another 2 mi. of the cholesterol solution. Pour rapidly the former on the latter. A fine suspension, stable for some days will result, but preferibly it must be prepared each time before use.

Procedure

In the bottom of a small test tube (90 X 130 mm.) put 0.2 ml. of fresh serum and add 4 mi. of the cholesterol suspension, mixing by inversion without shaking and allowing to stand at room temperature. Preparation of a control tube with the reagent is advisable.

Examine the tubes 24 hours later. A small sediment = +, partial floculation (some cholesterol remaining in solution) = ++, and complete floculation= +++. Negative serums do not give any sediment; but occasionally a turbidity, as compared with the control tube.