Cerebral vascular permeability and cellular infiltration in experimental allergic encephalomyelitis

Cerebral vascular permeability was measured in guinea-pigs developing experimental allergic encephalomyelitis (EAE). A sensitive double radio-isotope method was used which allowed the permeability changes to be measured independently of alterations in cerebral blood volume. The onset of the disease was accompanied by a striking increase in vascular permeability, but there was no evidence that this change preceded the entry of inflammatory cells into the brain and cord. Injection of serum from rabbits with EAE into normal guinea-pigs had no measurable effect on the cerebral vessels.

These findings are consistent with the view that EAE is a cell-mediated lesion and provide no support for the suggestion that the initial damage is due to circulating antibody.

     

Sevoflurane: a new inhalational anesthetic agent.

Laboratory screening of a series of halogenated methyl isopropyl ethers revealed sevoflurane (fluoromethyl-1,1,1,3,3,3,-hexafluroro-2-propyl ether) as a potent nonexplosive inhalational anesthetic agent. Sevoflurance, a pleasant-smelling liquid, boils at 58.5 degrees C at 760 torr and has a vapor pressure of 200 torr at 25 degrees C. It is nonflammable in air and has lower flammability limits of 11 vols percent in O2 and 10 vols percent in N2O. Sevoflurane exhibits limited chemical reactivity in vitro; it is subject to slight but measurable hydrolysis, and reacts with soda lime to form traces of related ethers. It provides rapid anesthetic induction and recovery consistent with its low distribution coefficients (blood:gas, 0.6; corn oil:gas, 41.6; olive oil:gas, 53.4). In dogs, anesthetic concentrations of sevoflurane did not produce spontaneous cardiac arrhythmias and did not sensitize the heart to epinephrine. Electroencephalographic patterns were similar to those observed during anesthesia with halothane. In rats, small increases in the urinary excretion of inorganic fluoride ion occurred during the first 24 hours after anesthesia. Subacute studies in dogs and rats, using closed-circle absorption with soda lime, revealed no toxicologically significant changes in animals anesthetized frequently for 2 weeks. Sevoflurane appears to be a unique volatile anesthetic agent worthy of further study.