STUDIES ON BLOOD COAGULATION : I. THE R?LE OF PROTHROMBIN AND OF PLATELETS IN THE FORMATION OF THROMBIN

1. A method is described for the preparation and titration of prothrombin and thrombin. 2. Confirming the views of Morawitz, Howell (1916–17, 1925), and Bordet, thrombin cannot be regarded as an artificial by-product of coagulation (Wooldridge, Nolf (both quoted from Morawitz)). Calcium, a platelet factor, and a plasma factor (prothrombin) interact to form thrombin, and this then acts upon fibrinogen to form fibrin. The amount and rate of thrombin formation in the first reaction are independent of the presence or absence of fibrinogen. After a variable latent period, thrombin suddenly appears in large quantities, coincident with or immediately preceding the deposition of fibrin if fibrinogen is present. 3. The amount of thrombin formed in a mixture of prothrombin, Ca and platelets is independent of the platelet or Ca concentration, and depends primarily upon the amount of prothrombin used. The platelets (or cephalin) enormously accelerate the transformation of prothrombin to thrombin, and this acceleration seems to be their physiological rôle in the coagulation process. 4. Contrary to previous reports, platelets have not been demonstrated to contain significant quantities of prothrombin. 5. The available data do not allow any definite decision as to whether the platelet factor actually combines with prothrombin to form thrombin, or merely catalyzes the transformation. The very slow formation of thrombin in the complete absence of platelets may be due to dissolved traces of platelet material released during the physical manipulation of the plasma (centrifuging, Berkefeld filtration). 6. There was no evidence for a species-specific activity of platelets in the transformation of prothrombin to thrombin.     

DONNAN EQUILIBRIUM AND THE PHYSICAL PROPERTIES OF PROTEINS : IV. VISCOSITY—Continued.

1. The proof is completed that the influence of electrolytes on the viscosity of suspensions of powdered particles of gelatin in water is similar to the influence of electrolytes on the viscosity of solutions of gelatin in water. 2. It has been suggested that the high viscosity of proteins is due to the existence of a different type of viscosity from that existing in crystalloids. It is shown that such an assumption is unnecessary and that the high viscosity of solutions of isoelectric gelatin can be accounted for quantitatively on the assumption that the relative volume of the gelatin in solution is comparatively high. 3. Since isoelectric gelatin is not ionized, the large volume cannot be due to a hydration of gelatin ions. It is suggested that this high volume of gelatin solutions is caused by the existence in the gelatin solution of submicroscopic pieces of solid gelatin occluding water, the relative quantity of which is regulated by the Donnan equilibrium. This would also explain why the influence of electrolytes on the viscosity of gelatin solutions is similar to the influence of electrolytes on the viscosity of suspensions of particles of gelatin. 4. This idea is supported by experiments on solutions and suspensions of casein chloride in which it is shown that their viscosity is chiefly due to the swelling of solid particles of casein, occluding quantities of water regulated by the Donnan equilibrium; and that the breaking up of these solid particles into smaller particles, no longer capable of swelling, diminishes the viscosity. 5. This leads to the idea that proteins form true solutions in water which in certain cases, however, contain, side by side with isolated ions and molecules, submicroscopic solid particles capable of occluding water whereby the relative volume and the viscosity of the solution is considerably increased. This accounts not only for the high order of magnitude of the viscosity of such protein solutions but also for the fact that the viscosity is influenced by electrolytes in a similar way as is the swelling of protein particles. 6. We therefore reach the conclusion that there are two sources for the viscosity of protein solutions; one due to the isolated protein ions and molecules, and the other to the submicroscopic solid particles contained in the solution. The viscosity due to the isolated molecules and ions of proteins we will call the general viscosity since it is of a similar low order of magnitude as that of crystalloids in solution; while the high viscosity due to the submicroscopic solid protein particles capable of occluding water and of swelling we will call the special viscosity of protein solutions. Under ordinary conditions of hydrogen ion concentration and temperature (and in not too high a concentration of the protein in solution) the general viscosity due to isolated ions and molecules prevails in solutions of crystalline egg albumin and in solutions of metal caseinates (where the metal is monovalent) while under the same conditions the second type of viscosity prevails in solutions of gelatin and in solutions of acid-salts of casein; and also in solutions of crystalline egg albumin at a pH below 1.0 and at higher temperatures. The special viscosity is higher in solutions of gelatin than of casein salts for the probable reason that the amount of water occluded by the submicroscopic solid gel particles in a gelatin solution is, as a rule, considerably higher than that occluded by the corresponding particles of casein.     

LOSS OF BLOOD AT OPERATION—A Method for Continuous Measurement

A method for continuous measurement of surgical blood loss has been devised and has been used clinically in some 400 cases. The method combines volumetric measure of the suction loss and gravimetric measure of the sponge loss. The volumetric device automatically deducts the volume of rinse water used and thus measures the amount of blood collected in a metering cylinder. The suction loss scale shows continuously the amount of blood in the metering cylinder. The gravimetric device requires counting sponges into the weighing pan, and turning a dial scale to deduct the initial weight of the sponges. The volume of blood in the sponges is then read directly on the dial scale. Use of the instrument, which is under the supervision of the anesthesiologist, adds about two minutes per hour to the time normally required for counting the sponges; and about three minutes per hour is required for tending the volumetric instrument.In clinical use, knowing constantly the amount of blood loss permits the starting of transfusion before serious deficit develops, and then maintaining the patient''s blood volume at a predetermined optimum level. In some 400 cases the continuous measurement of the blood loss served as a reliable guide for carrying out the loss-replacement plan within close limits of accuracy.     

THE RELATIONS OF THE INDIVIDUAL AMPULL? OF THE SEMICIRCULAR CANALS TO THE INDIVIDUAL EYE MUSCLES : I. THE HORIZONTAL CANALS.

1. The reflex effect of direct mechanical stimulation of the exposed ampulla of the horizontal canal has been graphically recorded for each of the six extrinsic muscles of the eyeball. 2. Stimulation of a horizontal ampulla evokes a strong contraction of the homolateral rectus internus and of the contralateral rectus externus; at the same time the homolateral rectus externus and the contralateral rectus internus relax. 3. A single mechanical stimulus applied to the horizontal ampulla is sometimes followed by a nystagmus resulting from a series of rhythmic contractions of the externus and internus muscles. 4. Excitation of a horizontal ampulla gives rise to weak contractions of the superior and inferior recti and of the two oblique muscles of both eyes, simultaneously with the stronger contractions of the externus and internus respectively. 5. It is pointed out that the small simultaneous contractions of the four muscles just mentioned provide a virtual axis upon which the eyeball rotates. In other words these four act as fixation muscles. 6. It is suggested that some of the abnormal responses to horizontal rotation, seen in clinical cases, are due to the inaction of one or more of the fixation muscles.