染色体的稳定需要端粒DNA保持一定的长度,端粒保持机制的激活在细胞永生和肿瘤发生中具有重要的作用。大部分人肿瘤细胞利用端粒酶来维持端粒DNA长度的稳定,然而在某些缺乏端粒酶活性的肿瘤细胞中,端粒DNA长度的稳定主要是通过端粒延伸...染色体的稳定需要端粒DNA保持一定的长度,端粒保持机制的激活在细胞永生和肿瘤发生中具有重要的作用。大部分人肿瘤细胞利用端粒酶来维持端粒DNA长度的稳定,然而在某些缺乏端粒酶活性的肿瘤细胞中,端粒DNA长度的稳定主要是通过端粒延伸替代机制(alternative lengthening of telomeres,ALT)来完成的。抑制端粒DNA保持机制的抗肿瘤治疗的发展将促进认识ALT及其在正常细胞中被抑制的机制。同时,对ALT机制的深入研究也将促进端粒抑制剂抗肿瘤治疗的发展。展开更多
端粒长度的维持在肿瘤细胞的永生化过程中起到至关重要的作用。约85%的人体肿瘤细胞通过端粒酶延伸端粒,从而获得持续的增殖能力。另外,15%的人体肿瘤细胞通过端粒替代延伸机制(alternative lengthening of telomeres,ALT)延伸端粒。这...端粒长度的维持在肿瘤细胞的永生化过程中起到至关重要的作用。约85%的人体肿瘤细胞通过端粒酶延伸端粒,从而获得持续的增殖能力。另外,15%的人体肿瘤细胞通过端粒替代延伸机制(alternative lengthening of telomeres,ALT)延伸端粒。这两种机制对于维持肿瘤细胞中端粒的长度具有同等重要的意义。人体端粒由富含鸟嘌呤(G)的DNA重复序列组成,该序列在特定的条件下可以形成G-四链体(G4)的结构。此结构的形成可以从根本上抑制端粒酶和ALT对端粒的延伸而达到抗肿瘤的目的。因此,人体端粒G4-DNA作为抗肿瘤靶点的研究是近年来抗肿瘤研究的重要前沿领域之一。该文重点综述人体端粒G4-DNA稳定剂研发的最新研究进展。展开更多
The volume expansion of the stuff (e. g. tobacco stem) is of great importance to an increase in the product quality and a decrease in the production cost This paper puts forward the basic configuration and the expansi...The volume expansion of the stuff (e. g. tobacco stem) is of great importance to an increase in the product quality and a decrease in the production cost This paper puts forward the basic configuration and the expansion mechanism of a new type of jet pressurization evaporation expansion apparatus. By the thermodynamic calculation of the apparatus, we give variations in steam pressure on various cross sections of the flow system for the apparatus, manufacture a sample machine, and finish run tests of the machine. The test results show that the apparatus may make the relative increase in fill value of tobacco stem higher than 75%. and may cause the steam consumption required in the expansion process of each kilogram stem to reduced about 40% compared with conventional expansion apparatus. Additionally, the configuration of the apparatus is simple and small, its cost of manufacture is very low, and both its operation and maintenance are extremely convenient.展开更多
文摘染色体的稳定需要端粒DNA保持一定的长度,端粒保持机制的激活在细胞永生和肿瘤发生中具有重要的作用。大部分人肿瘤细胞利用端粒酶来维持端粒DNA长度的稳定,然而在某些缺乏端粒酶活性的肿瘤细胞中,端粒DNA长度的稳定主要是通过端粒延伸替代机制(alternative lengthening of telomeres,ALT)来完成的。抑制端粒DNA保持机制的抗肿瘤治疗的发展将促进认识ALT及其在正常细胞中被抑制的机制。同时,对ALT机制的深入研究也将促进端粒抑制剂抗肿瘤治疗的发展。
文摘端粒长度的维持在肿瘤细胞的永生化过程中起到至关重要的作用。约85%的人体肿瘤细胞通过端粒酶延伸端粒,从而获得持续的增殖能力。另外,15%的人体肿瘤细胞通过端粒替代延伸机制(alternative lengthening of telomeres,ALT)延伸端粒。这两种机制对于维持肿瘤细胞中端粒的长度具有同等重要的意义。人体端粒由富含鸟嘌呤(G)的DNA重复序列组成,该序列在特定的条件下可以形成G-四链体(G4)的结构。此结构的形成可以从根本上抑制端粒酶和ALT对端粒的延伸而达到抗肿瘤的目的。因此,人体端粒G4-DNA作为抗肿瘤靶点的研究是近年来抗肿瘤研究的重要前沿领域之一。该文重点综述人体端粒G4-DNA稳定剂研发的最新研究进展。
文摘The volume expansion of the stuff (e. g. tobacco stem) is of great importance to an increase in the product quality and a decrease in the production cost This paper puts forward the basic configuration and the expansion mechanism of a new type of jet pressurization evaporation expansion apparatus. By the thermodynamic calculation of the apparatus, we give variations in steam pressure on various cross sections of the flow system for the apparatus, manufacture a sample machine, and finish run tests of the machine. The test results show that the apparatus may make the relative increase in fill value of tobacco stem higher than 75%. and may cause the steam consumption required in the expansion process of each kilogram stem to reduced about 40% compared with conventional expansion apparatus. Additionally, the configuration of the apparatus is simple and small, its cost of manufacture is very low, and both its operation and maintenance are extremely convenient.
