By using a cre-lox conditional knockout strategy, we report here the generation of androgen receptor knockout (ARKO) mice. Phenotype analysis shows that ARKO male mice have a female-like appearance and body weight. Their testes are 80% smaller and serum testosterone concentrations are lower than in wild-type (wt) mice. Spermatogenesis is arrested at pachytene spermatocytes. The number and size of adipocytes are also different between the wt and ARKO mice. Cancellous bone volumes of ARKO male mice are reduced compared with wt littermates. In addition, we found the average number of pups per litter in homologous and heterozygous ARKO female mice is lower than in wt female mice, suggesting potential defects in female fertility and/or ovulation. The cre-lox ARKO mouse provides a much-needed in vivo animal model to study androgen functions in the selective androgen target tissues in female or male mice

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Using flow cytometric assay and monoclonal anti-dengue Ab, we observed that both anti-E and anti-prM Abs could enhance dengue virus infection in a concentration-dependent but serotype-independent manner. Increases were found in both the percentage of dengue-infected cells and the expression of dengue E and NS1 protein per cell. Dengue virion binding and infection were enhanced on FcR-bearing cells via the Fc-FcγRII pathway. Furthermore, anti-prM Ab also enhanced dengue virion binding and infection on cells lacking FcR, such as BHK-21 or A549 cells, by the mechanism of peptide (CPFLKQNEPEDIDCW)-specific binding. Anti-prM Ab cross-reacted with BHK-21 or A549 cells and recognized self-Ags such as heat shock protein 60. In summary, a novel mechanism of anti-prM Ab-mediated enhancement on dengue virus infection was found to be mediated by dual specific binding to dengue virion and to target cells, in addition to the traditional enhancement on FcR-bearing cells.

Dengue virus infection causes dengue fever, dengue haemorrhagic fever and dengue shock syndrome. No animal model is available that mimics these clinical manifestations. In this study, the establishment is reported of a murine model for dengue virus infection that resembles the thrombocytopenia manifestation. Dengue-2 virus (dengue virus type 2) can infect murine cells either in vitro (primary cell culture) or in vivo. Viraemia detected by RT-PCR was found transiently at 2 days after intravenous injection of dengue-2 virus. Transient thrombocytopenia developed at 10-13 days after primary or secondary infection. Anti-platelet antibody was generated after dengue-2 virus infection. There was strain variation in dengue-2 virus infection ; the A/J strain was more sensitive than BALB/c or B6 mice. This dengue-2-virus-infected mouse system accompanied by thrombocytopenia and anti-platelet antibody will be a valuable model to study the pathogenicity of dengue virus infection.

Purpose:To assess the use of the dual-energy computed tomographic (CT) virtual noncalcium technique in the evaluation of bone marrow edema in vertebral compression fractures. Materials and Methods:This prospective study was approved by the institutional review board; informed consent was obtained from all patients. Sixty-three consecutive patients with 112 thoracic and/or lumbar vertebral compression fractures were studied between January 2011 and April 2012. All patients underwent both dual-energy CT (100 kV and Sn140 kV, where Sn indicates the use of a 0.4-mm tin filter) and magnetic resonance (MR) imaging. Dual-energy CT data were postprocessed by using a three-material decomposition algorithm for generating noncalcium images of the collapsed bodies. Two radiologists evaluated for the presence of abnormal attenuation alterations in the bone marrow by using color-coded maps and measured CT numbers on noncalcium grayscale images. Bone sclerosis and intravertebral air were evaluated with CT scans. MR images served as the reference standard. CT numbers were subjected to receiver operating characteristic curve analysis. Results:MR imaging depicted 46 edematous and 66 nonedematous vertebral compression fractures. Eighty-two bodies were classified as having less than 50% sclerosis and/or air. Significant differences in noncalcium CT numbers between edematous and nonedematous vertebral compression fractures were found for both readers (P , .0001).CT numbers for the diagnosis of bone marrow edema on the basis of MR imaging revealed areas under the receiver operating characteristic curve of 0.799 and 0.841 for readers 1 and 2, respectively (P = .56). Use of a cutoff value of 280 to differentiate edematous vertebral bodies resulted in a sensitivity of 96.3%, specificity of 98.2%, and accuracy of 97.6% in the group of vertebral bodies with less than 50% sclerosis and/or air. Conclusion:Dual-energy CT virtual noncalcium images were able to depict bone marrow in the collapsed vertebral bodies, especially in those with less than 50% sclerosis and/or air.q RSNA, 2013