A Grafting Strategy for the Design of Improved G-Quadruplex Aptamers and High-Activity DNAzymes

Nucleic acid aptamers are generally obtained by in vitro selection. Some have G-rich consensus sequences with ability to fold into the four-stranded structures known as G-quadruplexes. A few G-quadruplex aptamers have proven to bind hemin to form a new class of DNAzyme with the peroxidase-like activity, which can be significantly promoted by appending an appropriate base-pairing duplex onto the G-quadruplex structures of aptamers. Knowing the structural role of base pairing, here we introduce a novel grafting strategy for the design of improved G-quadruplex aptamers and high-activity DNAzymes. To demonstrate this strategy, three existing G-quadruplex aptamers are chosen as the first generation. A base-pairing DNA duplex is grafted onto the G-quadruplex motif of the first generation aptamers. Consequently, three new aptamers with the quadruplex/duplex DNA structures are produced as the second generation. The hemin-binding affinities and DNAzyme functions of the second generation aptamers are characterized and compared with the first generation. The results indicate three G-quadruplex aptamers obtained by the grafting strategy have more excellent properties than the corresponding original aptamers. Our findings suggest that, if the structures and functions of existing aptamers are thoroughly known, the grafting strategy can be facilely utilized to improve the aptamer properties and thereby producing better next-generation aptamers. This provides a simple but effective approach to the design of nucleic acid aptamers and DNAzymes

Radical Cystectomy and Orthotopic Bladder Substitution Using Ileum

Over the past decade, continent urinary diversion, especially orthotopic bladder substitutions, has become increasingly popular following radical cystectomy for bladder cancer. The ultimate goal of orthotopic bladder substitution is to offer patients the best quality of life, similar to that of patients with native bladders. To achieve that purpose, surgeons should be familiar with the characteristics of good candidates for neobladders, the possible intraoperative and postoperative problems related to the surgery, and the solutions to these problems. Postoperative surveillance and instructions given to the patients also contribute to successful, functional results. Here, we reviewed the indications, pitfalls, and solutions for orthotopic bladder substitutions and the patients' quality of life after surgery. When performed properly, orthotopic continent diversion offers good quality of life with few long-term complications. Therefore, we believe it is the best option for the majority of patients requiring cystectomy