ABSTRACT
BACKGROUND: A new version of the Roche Cobas AmpliPrep/Cobas TaqMan HIV-1 assay (CA/CTM v2.0) has been introduced to overcome the underquantification observed with the first version. METHODS: We compared the Roche Cobas CA/CTM v2.0 and Abbott RealTime HIV-1 assays for HIV-1 group M and non-M viral load measurement. RESULTS: We found a good correlation (r = 0.96) between the 2 techniques for the 260 HIV-1 group M plasma samples tested. The Roche Cobas assay gave significantly higher values than the Abbott assay, and 51 samples (20%) yielded differences greater than 0.5 log10 copies per milliliter. Conversely, 2 samples were more than 0.5 log10 copies per milliliter higher with the Abbott assay than with the Roche Cobas assay. Among the 84 samples with undetectable viral load in the Abbott assay (detection limit 40 copies/mL), 17 (20%) were detectable with the CA/CTM v2.0 assay (detection limit 20 copies/mL), with values ranging from 41 to 897 copies per milliliter. Extrapolation of the Abbott curves led to 10/17 (59%) of these samples being quantifiable. HIV-1 groups O and P were similarly quantified by the two techniques. CONCLUSION: The results of the Roche Cobas CA/CTM v2.0 and Abbott RealTime HIV-1 assays correlate well. The new version of the CA/CTM assay shows improved sensitivity. Nevertheless, the 2 assays differ by more than 0.5 log10 copies per milliliter for some samples.
Subject(s)
HIV-1/isolation & purification , Polymerase Chain Reaction/methods , RNA, Viral/isolation & purification , Viral Load/methods , HIV-1/genetics , Humans , RNA, Viral/genetics , Reagent Kits, DiagnosticABSTRACT
The impact of P-glycoprotein (P-gp) on the distribution of quinine between brain and plasma was studied experimentally in mice. Administration of quinine (20mg/kg, i.v.) to mdrla knockout mice resulted in enhanced brain concentrations of quinine as compared to the wild-type mice (7.9+/-1.4 microg/g versus 1.6+/-0.8 microg/g, respectively). Quinine concentrations and quinine-to-3-hydroxyquinine ratio in plasma were similar in normal and P-gp-deficient mice. The effect of intravenously administered drugs before quinine (20mg/kg, i.v.) was evaluated on brain uptake and biotransformation of quinine in mice. Cyclosporine A (50 mg/kg), erythromycine (40 mg/kg), verapamil (5mg/kg) or mefloquine (20 mg/kg) increased the brain-to-plasma quinine concentration ratio (by factors of 3.8-, 1.8-, 1.9- and 2.5-fold, respectively) and the quinine-to-3-hydroxyquinine ratio in plasma (by factors 2.1-, 3.7-, 1.8- and 2.0-fold, respectively). After cinchonine (40 mg/kg) and halofantrine (40 mg/kg) pre-treatment, the brain-to-plasma ratio for quinine increased by factor of 2.3 and 1.8, respectively without changes of quinine or metabolite concentrations in plasma. Doxycycline (20 mg/kg), artesunate (50 mg/kg) or artemether (50 mg/kg) did not alter quinine disposition. These results confirm in vivo that quinine is a substrate for mdr1a P-gp. Drug associations led not only to metabolic interactions but also increased quinine uptake by tissues protected by P-gp. Such interactions may have implications for the improvement of chemotherapy but should be also taken into account for potential enhancement of adverse effects.
