Prion clearance in bigenic mice.

The clearance of prions from the brain was investigated in bigenic mice designated Tg(tTA : PrP(+/0))3, in which expression of the cellular prion protein (PrP(C)) was regulated by oral doxycycline administration. With suppression of PrP(C) expression, the incubation time for RML prions was prolonged almost threefold from approximately 150 to approximately 430 days. To determine the clearance rate of disease-causing PrP(Sc), bigenic mice were given oral doxycycline beginning 98 days after inoculation with RML prions and sacrificed at various time points over the subsequent 56 days.

Multicenter evaluation of the Abbott LCx Mycobacterium tuberculosis ligase chain reaction assay.

Four Australian hospital laboratories evaluated the performance of the Abbott LCx Mycobacterium tuberculosis assay with 2,347 specimens (2,083 respiratory and 264 nonrespiratory specimens) obtained from 1, 411 patients. A total of 152 specimens (6.5%) were culture positive for Mycobacterium tuberculosis complex (MTBC); of these, 79 (52%) were smear positive.