Autoregulation of cerebral blood flow. Electromagnetic flow measurements during acute hypertension in the monkey

Changes in blood flow through the internal carotid, vertebral and external carotid arteries were measured by electromagnetic flowmeters during and after acute hypertension induced by closing a clamp around the thoracic aorta in anesthetized monkeys.

The internal carotid and vertebral arterial system showed both rapid and delayed autoregulatory responses to rapid increases in blood pressure; the rapid (primary) responses occurred within seconds, the progressive (delayed) within 3 to 4 minutes. In contrast, the flow response within the external carotid system appeared to be passive. Cervical sympathetic innervation and myogenic reflexes (Bayliss reflex) both appear to play a part in the rapidly occurring (primary) regulation of cerebral blood flow. The mechanism responsible for delayed and progressive (secondary) autoregulation in the cerebral vasculature appeared to be metabolic, since it was predominantly influenced by changes in blood Pco 2 . Changes in intracranial pressure did not seem to be involved in autoregulation.

THE IDENTITY OF BAYERITE-a AND BAYERITE-b

not available

Diagnosis of Glanders by Precipitation with So-Called “Soluble Specific Substance” Derived from B. Mallei

Two substances could be isolated from culture filtrate of B. mallei, of which one seems to be the nucleoprotein in nature and the other the specific substance analogous to that of pneumococcus, streptococcus etc. Preliminary chemical examination indicates that this specific substance may belong to carbohydrates. The former—the so-called N.P.—is relatively nonspecific and gives rise to nonspecific precipitation. The relative nonspecificity of the precipitation reaction with the culture filtrate (or mallein) seems to depend upon this substance. The latter substance is highly specific; it gives rise to precipitation only with sera of infected or artificially immunized animals, but not with those of animals neither infected nor immunized with B. mallei. Specific precipitation with this specific substance is closely related to the complement-fixation reaction. The precipitation test with this specific substance appears the most simple and reliable means for the practical diagnosis of glanders applicable as well to mules and donkeys, as to horses.