Richard B. Davis

Comparative Studies of Blood Coagulation and Platelet Aggregation in Patients with Cancer and Nonmalignant Diseases

Abstract Blood coagulation and platelet function was evaluated in 106 hospitalized patients with cancer and compared with 40 patients with nonmalignant diseases and 50 normal subjects. The mean val...

Immediate Effects of Intravenous Endotoxin on Serotonin Concentrations and Blood Platelets

Adult mongrel dogs were given a lethal dose of E. Coli endotoxin by rapid intravenous injection. Total serotonin levels in the serum fell rapidly, with the concentration in the portal vein and pulmonary artery significantly exceeding that in the femoral artery within the first minute after injection. Small rises in plasma serotonin were found in some of the animals. These changes were coincident with a sharp fall in the number of circulating platelets, with striking changes in platelet morphology, and with the initial fall in blood pressure.

Localization of 5‐Hydroxytryptamine in Blood Platelets: An Autoradiographic and Ultrastructural Study

5‐Hydroxytryptamine (serotonin, 5‐HT) was found by electronmicroscope autoradiography to be localized in dense granules in platelets. Evidence of radioactivity from tritium‐labelled 5‐HT was also found at other sites within platelets, but without evidence of concentration at those sites. Studies on human platelets showed that the dense granules were present in different forms, and structural evidence suggested that the dense granules containing 5‐HT may be derived from alpha granules. After clotting of platelet‐rich plasma, and before the structural integrity of the platelets was lost, radioactivity was present in relation to dense granules, but had been lost from other sites, suggesting firmer binding of 5‐HT to the granules.

Serotonin release by bacterial endotoxin.

Summary Within 15 seconds after rapid administration of E. coli endotoxin in the rabbit a significant release of serotonin into platelet-free plasma occurs in vivo. The magnitude of immediate serotonin release was cor-related with amount of endotoxin administered, and there was no significant rise of plasma serotonin with a non-lethal dose.

RAPID PULMONARY REMOVAL OF 5-HYDROXYTRYPTAMINE IN THE INTACT DOG.

Summary Simultaneous injection of indocyanine green dye and C14 5-HT was done in dogs to determine the extent of pulmonary removal of 5-HT. Cardiac output determined from C14 data was consistently higher than by the dye method, indicating immediate removal of 5-HT in the pulmonary bed. The mean removal was 33%, and was not changed by prior administration of β-phenylisopropylhydrazine, a monoamine oxidase inhibitor.

Familial Idiopathic Cardiomegaly

Two young adult sisters are described with clinical and pathologic findings of myocardial disease. These cases along with a suggestive family history are presented as examples of familial idiopathic cardiomegaly. Pathologic findings are compared and contrasted with those in the literature, and etiologic concepts are discussed. It is concluded that a congenital myocardial abnormality is the most likely etiology and suggestions for further studies are presented.

Swiss-Cheese Platelets

Excerpt To the editor: The recently published paper by Smith, Dodds, and Tartaglia (Ann Intern Med79:828-834, 1973) presents an excellent discussion of the vagaries of laboratory testing and the cl...

Effects of amine oxidase inhibition on E. coli endotoxin mortality in mice.

Summary M.A.O. inhibitors P.I.H., Nialamide and S.K.F. 556 were shown to have a small but significant effect in reducing mortality to intraperitoneal injection of E. coli endotoxin. Inhibition of M.A.O. alone appeared to have an effect distinct from inhibition of both M.A.O. and D.A.O. though the 3 drugs were not of significantly different potency.