Synthesis and antitumor activity of 4-demethoxyadriamycin and 4-demethoxy-4' -epiadriamycin

Two new analogs of adriamycin have been obtained by chemical synthesis, 4-demethoxyadriamycin and 4-demethoxy-4' -epiadriamycin. Both compounds were highly effective against experimental mouse tumors at doses about ten times lower than those effective for adriamycin. At the optimal dose, 4-demethoxyadriamycin displayed antitumor activity similar to that of adriamycin in solid Sarcoma 180 (S180), L1210, P388, and Gross leukemias, and mammary carcinoma, while it did not markedly inhibit the growth of Moloney sarcoma virus-induced sarcoma in mice treated before the virus infection. At the optimal dose, 4-demethoxy-4' -epiadriamycin was as active as adriamycin against L1210, P388,and Gross leukemias, and less active against solid S180. The results show that anthracycline derivatives characterized by the absence of the methoxyl group at the C-4 position are markedly more potent than the parent compound, and may exhibit a differential antitumor effect on a number of mouse tumors.     

Expressions of 2H4 and 4B4 antigens on ATL cells

We studied the expression of 2H4 and 4B4 on the surfaces of leukemia cells from 17 patients with adult T-cell leukemia (ATL) as well as of cells belonging to 2 T-cell lines derived from ATL patients. The effects of the supernatants obtained from culture fluids of the ATL cells and the T-cell lines on IgG production of a human B-cell line, CESS cells, were also examined. On the surfaces of the ATL cells from 15 out of 17 cases and of the cells of 2 T-cell lines 4B4 obviously existed at higher percentage than 2H4 and more than 80% of ATL cells from 16 out of these 17 cases showed the expression of T4 (CD4). These findings revealed that the most of ATL cells had a helper-inducer phenotype. Supernatants (Sups) of culture fluids of ATL cells from 4 patients and those of 2 T-cell lines were added at various concentrations to the CESS cells. In only 1 Sup from ATL patient enhanced the IgG production of the CESS cells at lower concentration. However, other 5 Sups suppressed the IgG production of the CESS cells in proportion to the increase of Sup added. These results showed that phenotypical type of ATL cells does not always correspond to their functions, and the ATL cells may produce humoral factors that regulate B cell functions.     

Behaviour of Microwave-Heated Al4SiC4 at 2.45 GHz

The ongoing development of high-temperature processes with the use of microwaves requires new microwave absorbers that are useful at these temperatures. In this study, we propose Al₄SiC₄ powders as important and efficient microwave absorbers. We investigated both the behavioural microwave heating and electrical permittivity characteristics of Al₄SiC₄ powders with various particle sizes at 2.45 GHz. The TE₁₀₃ single-mode cavity indicated that Al₄SiC₄ powder samples yielded different heating behaviours and dielectric constants for each particle size compared with SiC. By microwave heating ∅50 mm × 5 mm disks of Al₄SiC₄ and SiC, we demonstrate that for specific sizes, Al₄SiC₄ can be heated at a higher temperature than SiC. Finally, the results of the two-dimensional two-colour thermometer show that an energy concentration appears at the interface of the microwave-heated Al₄SiC₄. These phenomena, which are inconsistent in individual physical property values, can be explained without contradicting microwave heating physics.     

DPC4/SMAD4基因与结肠癌

DPC4/SMAD4是一种新的肿瘤抑制基因,定位于第18号染色体长臂18q21.1的位置.它编码的蛋白SMAD4参与了转移生长因子β(TGF-β)超家族细胞内信号传导.SMAD4是信号传递蛋白SMADS的功能活动中心.本文就DPC4/SMAD4基因及其编码的蛋白的结构、功能、在信号传导途径中的作用和在结肠癌中的改变进行了综述.