Abstract
ABSTRACTS: We used a cranial window preparation to observe the effects of direct application of group B streptococci to the surface of the brain in the adult rat. Continuous exposure to group B streptococci at concentrations of 103 and 105 organisms/mL caused progressive dilation of surface (pial) cerebral arterioles that became statistically significant (p < 0.05) after 2.5 h. These results were reproduced with heat-killed organisms at the same concentration, but not with a bacteria-free filtrate of the growth medium. In separate studies, we found that infusion of alkaline cerebrospinal fluid (pH = 7.8) into the window did not reverse vasodilation, suggesting that it was not due to progressive cerebrospinal fluid acidosis. A solution of nitroblue tetrazolium infused into the window at the end of a 3-h exposure to the organism was promptly reduced, suggesting the presence of oxygen free radicals. Treatment with i.v. polyethylene glycol-superoxide dismutase and polyethylene glycol-catalase in doses of 10 000 and 20 000 U/ kg, respectively, was itself without effect on pial arterioles, but treatment with these compounds before exposure to group B streptococci eliminated the vasodilation. These data support a role for oxygen free radicals in the pathogenesis of pial arteriolar dysfunction induced by exposure to group B streptococci.
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McKnight, A., Keyes, W., Hudak, M. et al. Oxygen Free Radicals and the Cerebral Arteriolar Response to Group B Streptococci. Pediatr Res 31, 640–644 (1992). https://doi.org/10.1203/00006450-199206000-00020
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DOI: https://doi.org/10.1203/00006450-199206000-00020
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