Rheological analyses of coagulation of blood from different individuals with special reference to procoagulant activity of erythrocytes.

In our previous papers, we reported that factor IX (FIX), when activated by erythrocyte membranes, causes coagulation. We have identified and characterized the FIX-activating enzyme located in normal human erythrocyte membranes. In this paper, to examine physiological and pathological significances of procoagulant activity of erythrocytes, coagulation of blood obtained from different individuals was analyzed by means of a rheological technique. In more than 65% of subjects including normals and patients, the initiation of coagulation seemed to be governed by erythrocytes. Coagulation of whole blood and platelet-free plasma supplemented with erythrocytes had a tendency to occur rapidly in the elderly. It was suggested that the concentration of FIX-activating enzyme on erythrocyte membranes for aged donors was somewhat higher than that for young ages. Propagation reactions on erythrocyte membranes (i.e. factor X activation leading to thrombin generation after FIX activation) was slower than that on platelet membranes. Moreover, the propagation reaction on erythrocyte membranes was greatly dependent on individuals, whereas that on platelet membranes was not so much. Our study demonstrates that the activation of FIX by erythrocytes and subsequent propagation reaction on platelet membranes may be important for initiating and controlling blood coagulation reactions.

Pneumomediastinum following esophageal rupture associated with hyperemesis gravidarum.

A patient was diagnosed with pneumomediastinum caused by an esophageal rupture during hyperemesis gravidarum. The woman, at 15 weeks' gestation, presented with hyperemesis gravidarum complicated by an episode of chest pain and disturbance of consciousness. Radiological examination revealed pneumomediastinum and subcutaneous emphysema. They are normally caused by either pulmonary or esophageal rupture. The esophageal etiology was suspected as more likely because of the severe vomiting accompanied with it. Although the clinical feature was quite complicated and esophageal rupture is generally a life-threatening disease, we chose conservative therapy which resulted in rapid recovery. The final diagnosis was confirmed by endoscopic examination performed after recovery. Pneumomediastinum during pregnancy is rare but it could be lethal. Careful and considerate assessments including surgical treatment should be necessary.