The effect of green tea polyphenol fraction (GTP) on azoxymethane(AOM)‐induced colon carcino‐genesis was investigated in male Fischer rate. The rats were given AOM (7.4 mg/kg body weight) s.c. once a week for 10 weeks. A week after the treatment, they were divided into three groups: AOM‐control (26 rats), AOM‐GTP1 (26 rats) and AOM‐GTP2 (25 rats). AOM‐GTPl and AOM‐GTP2 groups respectively received 0.01 and 0.1% GTP in drinking water from week 11 to 26. AOM‐control group received tap water throughout this experiment. Autopsy on week 26 showed that tumor incidence and average numbers of tumors per rat in the AOM‐GTPl and AOM‐GTP2 groups were significantly lower than those of the AOM‐control group: 38.1% and 47.6% versus 77.3%; 0.6 and 0.7 versus 1.5. Thus, it was concluded that GTP inhibited the development of AOM‐indnced colon carcinogenesis. The inhibition by GTP did not show significant dose dependence.
A high-performance brain PET scanner, jPET-D4, which provides four-layer depth-of-interaction (DOI) information, is being developed to achieve not only high spatial resolution, but also high scanner sensitivity. One technical issue to be dealt with is the data dimensions which increase in proportion to the square of the number of DOI layers. It is, therefore, difficult to apply algebraic or statistical image reconstruction methods directly to DOI-PET, though they improve image quality through accurate system modelling. The process that requires the most computational time and storage space is the calculation of the huge number of system matrix elements. The DOI compression (DOIC) method, which we have previously proposed, reduces data dimensions by a factor of 1/5. In this paper, we propose a transaxial imaging system model optimized for jPET-D4 with the DOIC method. The proposed model assumes that detector response functions (DRFs) are uniform along line-of-responses (LORs). Then each element of the system matrix is calculated as the summed intersection lengths between a pixel and sub-LORs weighted by a value from the DRF look-up-table. 2D numerical simulation results showed that the proposed model cut the calculation time by a factor of several hundred while keeping image quality, compared with the accurate system model. A 3D image reconstruction with the on-the-fly calculation of the system matrix is within the practical limitations by incorporating the proposed model and the DOIC method with one-pass accelerated iterative methods.
Two indole alkaloids which induce the Epstein-Barr virus early antigen of Raji cells (B lymphocyte) were found in the cultured broth of Actinomycetes NA34-17, from which te1eocidin B. was also obtained. The active compounds isolated were identified from their spectral data and chemical evidence as (-)-indolactam V and (-)-14-0-acetyl indolactam V.
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