Tatsumi K, Sakane T, Sawada H, Shirakawa S, Nakamura T
Gan. 1975 Aug;66(4):441-4.
In an attempt to quantitate DNA repair induced by Neocarzinostatin, the incorporation of labeled thymidine into the human peripheral lymphocytes after exposure to the agent was studied by autoradiography. The exposure of lymphocytes to Neocarzinostatin for 60 min at the concentrations as low as 0.05 mug/ml caused a significant increase in the number of grains per cell within 2 hr of incubation with 10 muCi/ml of 3H-thymidine in the presence of 2mM of hydroxyurea. The number of grains increased with the increasing dose of the agent up to the concentration of around 2.5 mug/ml and then fell at higher concentrations. The extent of maximum incorporation induced by Neocarzinostatin was found to be almost comparable to that induced by 100 erg/mm2 of UV irradiation. Hydroxyurea or caffeine in the labeling medium showed little or no effect on the grain count, but acriflavine at 0.1 mM reduced the grain count by a factor of about 6. These results indicate that relatively high level of repair synthesis occurred in human lymphocytes after exposure to Neocarzinostatin and provide further evidence for the direct damage of cellular DNA induced by the antibiotic.
为了定量新制癌菌素诱导的DNA修复，通过放射自显影研究了人外周血淋巴细胞在接触该药物后标记胸苷的掺入情况。在2mM羟基脲存在下，将淋巴细胞暴露于低至0.05μg/ml浓度的新制癌菌素60分钟，然后与10μCi/ml的3H-胸苷一起孵育2小时，结果导致每个细胞的银粒数显著增加。随着药物剂量增加，银粒数增加，直至浓度达到约2.5μg/ml左右，然后在更高浓度下下降。发现新制癌菌素诱导的最大掺入程度几乎与100erg/mm2紫外线照射诱导的程度相当。标记培养基中的羟基脲或咖啡因对银粒计数几乎没有影响，但0.1mM的吖啶黄使银粒计数减少了约6倍。这些结果表明，人淋巴细胞在接触新制癌菌素后发生了相对高水平的修复合成，并为该抗生素诱导细胞DNA的直接损伤提供了进一步证据。
