The processing and collaborative assay of a reference endotoxin.

A preparation of Escherichia coli bacterial endotoxin, the latest of successive lots drawn from bulk material which has been studied in laboratory tests and in animals and humans for suitability as a reference endotoxin, has been filled and lyophilized in a large number of vials. Details of its characterization, including stability studies, are given. A collaborative assay was conducted by 14 laboratories using gelation end-points with Limulus amebocyte lysates. Approximate continuity of the unit of potency with the existing national unit was achieved. The lot was made from the single final bulk but had to be freeze-dried in five sublimators. An assessment was therefore made for possible heterogeneity. The results indicate that the lot can be used as a large homogeneous quantity. The advantages of using it widely as a standard for endotoxins are discussed.

Angiographic demonstration of congenital absence of both internal carotid arteries. Case report.

The authors present angiographic demonstration of bilateral, congenital, total absence of the internal carotid arteries in a patient with subarachnoid hemorrhage. Angiography demonstrated complete absence of both internal carotid arteries. The intracranial blood supply had been provided by communication between a hypertrophied basilar artery and the circle of Willis through the posterior communicating arteries. An aneurysm, believed to be the site of the subarachnoid hemorrhage, arose from the basilar artery. Absence of the carotid canals substantiated the congenital nature of the anomaly. The related embryology is reviewed.