No abstract

One critical factor in melanoma progression is the change from radial growth phase to vertical growth phase. We previously showed a high incidence of ras mutations in progressing but not early human melanomas. We also found that stable expression of activated Ras in a primary human melanoma cell line (WM35) led to enhanced proliferation, anchorage-independent survival, migration and invasion in vitro and enhanced subcutaneous tumor formation in vivo, transforming the melanoma phenotype from the radial growth phase to the vertical growth phase. Inhibitory cytokines, especially transforming growth factor-beta, are important in homeostasis of normal human melanocytes. Proliferation of early melanoma cells can be inhibited by transforming growth factor-beta, whereas more aggressive stages lose this response. Using a transforming growth factor-beta activated luciferase reporter transiently transfected into WM35, WM35N-ras, and WM35H-ras (WM35 transfected with mutant N-ras or H-ras genes), we demonstrated significant decreases (p < 0. 04) in transforming growth factor-beta induced reporter expression in both ras transfected cell lines. Transforming growth factor-beta also induced significant decreases (p < 0.002) in the proportion of WM35 cells in S-phase of the cell cycle; this effect was not observed in WM35N-ras cells. Furthermore, we demonstrated that an important controlling factor in transforming growth factor-beta inhibition of cell cycle progression, the phosphorylation of the Rb protein, was altered in WM35N-ras; transforming growth factor-beta caused a marked relative increase in hypophosphorylated pRb in WM35 cells, but not in WM35N-ras. These data suggest that activated Ras plays an important part in melanoma progression from the radial growth phase to the vertical growth phase by counteracting inhibition by cytokines such as transforming growth factor-beta, thus providing a growth advantage.

Abstract-Advances in reconstruction techniques and instrumentation improve image quality. Improved image quality could either improve confidence and diagnostic ability, or increase throughput, and lower injected dose. Current imaging guidelines give insuffient consideration to advances in iterative reconstruction methods that include collimator modeling, attenuation, and scatter correction, and best matched acquisitions. Thus advanced reconstruction is often sub-optimally used in a clinical setting. In this work, we first characterize the effects of various acquisition and reconstruction protocols with the explicit aim to reduce scan time without adverse affects as compared to FBP driven protocols. For this we characterize image features, such as nonuniformity and wall thickness of the cardiac insert inside the large anthropomorphic torso phantom (Data Spectrum) and correlate them with human observer ROC results. When reconstructing the data with OSEM with 3D collimator and detector response compensation ("Flash3D") we found that the detection ability is not impacted when using 6∞ angular steps, and thus reducing the acquisition time by 50%, as compared to the current method. A further reduction can be achieved if the rest study is scanned in the continuous instead of the step-and-shoot mode (10%). Dwell time can also be reduced slightly; however the myocardial count density should not be below at least 1 cnt/mm 2 for rest and summed stress. Clinical trials need to confirm the findings.

The autonomous parvoviruses are small, non-enveloped, single strand DNA viruses. They occur in many species and they have oncolytic properties. We are modifying the capsid of feline panleukopenia virus (FPV), a parvovirus which normally infects feline cells, with the goal of targeting human tumor cells for potential cancer therapy. Using recombinant viruses transducing a luciferase reporter, we show that insertion of a cyclically constrained, integrin-binding peptide at an exposed position on the FPV capsid enables transduction of an ␣v integrin-expressing human rhabdomyosarcoma cell line (Rh18A). These cells were not transduced by virus