Fourteen young Chinese marmots (Marmota bobak sibirica Radde) were randomly allocated to two groups of seven each. They were injected intrahepatically with a standard woodchuck hepatitis virus challenge pool or a negative pool, prepared from sera of woodchucks with and without woodchuck hepatitis virus infection, respectively. Marmot No. 2 in the experimental group experienced an episode of seroconversion from woodchuck hepatitis surface antigen to anti-woodchuck hepatitis antibody. Woodchuck hepatitis virus DNA was detected, and woodchuck hepatitis surface antigen particles of both spherical and filamentous forms and intact woodchuck hepatitis virus virions were found in its serum. By contrast, none of the control group animals (receiving the negative pool) produced any marker of woodchuck hepatitis virus. This suggests that young Chinese marmots can get woodchuck hepatitis virus infection.

Animals↗

PubMedDate not supplied

Species differences in the stereoselective hydrolysis of esmolol by blood esterases.

The stereoselective hydrolysis of esmolol was examined in blood from several species including humans. Blood esmolol esterase activity was in the order of guinea pigs greater than rats greater than rabbits greater than dogs greater than rhesus monkeys greater than humans. Dog and rat blood esterases hydrolyzed the (-)-enantiomer of esmolol faster than the (+)-enantiomer whereas rhesus monkey, rabbit, and guinea pig blood esterases hydrolyzed the (+)-enantiomer faster. Human blood esterases did not demonstrate stereoselectivity. Dog liver esterases also showed stereoselectivity towards the (-)-enantiomer but dog skeletal muscle esterases did not. Studies in mongrel dogs indicated that during esmolol infusions the concentration ratio of (-)-esmolol/(+)-esmolol was approximately 0.85. After termination of the esmolol infusion the (-)/(+) concentration ratio continuously decreased until (-)-esmolol was no longer quantifiable. These results indicate that stereoselective hydrolysis of esmolol occurs in vitro and in vivo.

Adrenergic beta-Antagonists↗