John P. Livoni

Intracranial fluid-blood levels in the anticoagulated patient

SummaryThis report documents that anticoagulation may cause multiple intracranial fluid-blood levels.

Neurospora crassa glycogen phosphorylase: Interconversion and kinetic properties of the "active" form

Abstract Glycogen phosphorylase in cell-free extracts of Neurospora crassa is activated 10- to 15-fold by incubation with MgATP2−. When the MgATP2− is removed, the active form (a form) reverts to the inactive form (b form). The inactivation requires Mg2+ and is inhibited by NaF. The results confirm that Neurospora crassa glycogen phosphorylase exists in two interconvertible forms and strongly suggests that the interconversion is catalyzed by a kinase and phosphatase. The a form was partially purified. The enzyme has a molecular weight of 320,000. Uridine diphosphate glucose is a linear competitive inhibitor with respect to glucose-1-phosphate and a linear non-competitive inhibitor with respect to glycogen. Glucose-6-phosphate is a hyperbolic (partial) noncompetitive inhibitor with respect to all substrates in both directions. The b form of the enzyme in crude cell-free extracts is stimulated 2- to 3-fold by 5′-AMP. As the b form is purified, the 5′-AMP activation is diminished. The molecular weight of the partially purified “b” form was also 320,000.

Unsuspected mediastinal hematoma diagnosed by computed tomography

A hemophiliac (factor VIII deficiency) was admitted with falling hematocrit after upper gastrointestinal bleeding. Computed tomography diagnosed a previously unsuspected large mediastinal hematoma. The use of CT in evaluating occult bleeding is discussed.

Multiloculated chronic posttraumatic aneurysm of the thoracic aorta with late acute rupture

A highly unusual case of a multiloculated chronic posttraumatic aneurysm of the thoracic aorta is presented. Angiographically, there was marked enlargement over a 7-year interval, resulting in acute rupture. The initial trauma had occurred over 30 years previously, emphasizing the need for a careful history in such patients.