To be 95% certain that an implanted TDR prosthesis has any sagittal motion, a ROM of at least 4.6 degrees must be observed, which is the upper limit of intraobserver measurement variability for a TDR with a true ROM of 0 degrees. To be 95% certain that a change in TDR ROM has occurred between 2 measurements by the same observer, a change in ROM of at least 9.6 degrees must be observed (the entire range of +/-4.6 degrees intraobserver variability). ROM measurement variability should be considered when evaluating the success or failure of motion preservation in lumbar TDR.

Despite optimal preoperative prognostic factors and excellent functional outcomes, MRI evidence of early articular cartilage degeneration was present in both partial medial and lateral meniscectomy patients at a minimum 5-year follow-up. Results support the use of cartilage-sensitive MRI as a noninvasive screening technique to evaluate cartilage changes after arthroscopic partial meniscectomy and may help to counsel the high-risk patient in regard to postoperative activity.

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IntroductionMacrophages play an important role in HIV, where they are a cellular reservoir. Macrophages are polarized into two phenotypes: pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages, which may have altered expression of drug efflux transporters, including BCRP and MRP1. These differences may result in subtherapeutic concentrations of antiretrovirals inside of macrophages and viral replication.MethodsU937 and U1 cells were polarized to the M1 or M2 phenotype via IFN-γ and LPS, or IL-4, IL-13, and LPS. Transporter expression was assessed via PCR and Western blotting, and transporter function was assessed via fluorescent dye assays. Transporter function was blocked with the inhibitors MK571 or KO143. Protein expression was confirmed in monocyte-derived macrophages. p24 production was assessed in U1 cells via enzyme-linked immunosorbent assay.ResultsmRNA and protein analysis demonstrated higher expression of MRP1 in M1 macrophages, while BCRP expression was downregulated in M1 macrophages. Treatment with inhibitors of transporter function decreased the difference in intracellular fluorescence between polarized macrophages. Differences in protein expression, which were observed with U937 cells, were confirmed in monocyte-derived macrophages. M1, but not M2 cells treated with MK571, showed decreased p24 production, consistent with reported MRP1 transporter expression.ConclusionsThese results support our hypothesis that there is differential expression of MRP1 and BCRP on M1 and M2 polarized macrophages and suggests that these differences may result in altered intracellular concentrations of antiretrovirals in macrophages and alter viral production in these cells. Targeting these differences may be a strategy to decrease viral replication in HIV-infected individuals.

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