[Synthesis and antisense properties of 2'ß-F- and 2'α-F-2'-deoxy-uridines modified oligonucleotides with 4'-C-(2-methoxyethoxy) substituent].

Chemical modification is critical for the therapeutic applications of antisense oligonucleotides. Novel 4'-C-MOE and 2'-fluoro- modified monomer 2'-F-4'-C-MOE-ara U and its epimeric 2'-F-4'-C-MOE-r U were synthesized from 2'-fluorinated arabinourine (2'-F-ara U) and 2'-fluorouridine(2'-F-r U), respectively. Their phosphoramidites were synthesized and successfully incorporated into oligodeoxynucleotides. The mismatch discrimination ability of these unnatural monomers and their effect on thermal stability were evaluated in the context of ds DNA and DNA-RNA chimeras. The thermal denaturation studies showed that the incorporation of 2'-F-4'-C-MOE-ara U led to enhanced binding affinity to complementary RNA strand and almost equivalent binding ability to complementary DNA, when compared with 2'-F-4'-C-MOE-r U and 2'-F-ara U modified duplexes. Especially a C-H(…)F-C pseudohydrogen bond was supposed to contribute more binding affinity at uridine-purine steps, meanwhile, 2'-F-4'-C-MOE-ara U had almost the same base discriminatory ability as uridine in ds DNA and DNA-RNA chimeras, while 2'-F-4'-C-MOE-r U was found to have only moderate RNA hybridization ability. However, 2'-F-4'-C-MOE-araU at 3'-end of oligonucleotide could not led to more nuclease hydrolytic stability than that with 2'-F-4'-C-MOE-r U modification. These results demonstrated the feasibility of C4'-MOE modification on 2'-F-ANA and the dramatic effects of the 2'-F substituent, which provides a new approach for further chemical modification of antisense drugs.

[Metabolite profiling of two anti-HIV lead compounds in rat liver microsomes].

The metabolite profiling of DAPA-7012 and DAAN-4442, the lead compounds from two new kinds of non-nucleoside reverse transcriptase inhibitors (NNRTIs), was performed using an ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), with the assistance of a metabolite data processing software. By utilizing the mass defect filter (MDF) technique, the data acquired from the 0 h-incubation and the 2 h-incubation were compared and analyzed with the MetaboLynx software. After incubation, 14 metabolites of DAPA-7012 and 14 metabolites of DAAN-4442 were found in rat liver microsome. The MS2 spectra for some metabolites were obtained using the MS(E) technique to get fragment ions for structural elucidation. The results indicated that both compounds could undergo extensive metabolism in rat liver microsomes. The major phase I reaction was oxidation/hydroxylation. The major phase II reaction was S-glutathione conjugation. The metabolic pathways were similar between the two lead compounds, though they have different backbone structures. Besides, the 4-NO2 of ring B in DAAN-4442 was susceptible to reduction, the benzyl of ring C in DAPA-7012 was tend to be oxidized. The common metabolic soft spots were primary amine of ring B and two methyl groups of ring C. Early SAR results showed that the primary amine and methyl were necessary substituent groups. The stability of these active groups needs to be improved and optimized. The approach of combining metabolites information and structure-activity analysis can provide a reference for further structural optimization.

[Design, synthesis and biologic evaluation of diarylbenzimidazole derivatives as novel HIV-1 non-nucleoside reverse transcriptase inhibitors].

Twenty seven new diarylbenzimidazole derivatives (A1-A21, B1-B6) were designed, synthesized, and evaluated in MT-2 cell line as potential HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs) agents with a new skeleton based on molecular modeling technique and hit 1,2-diarylbenzimidazole A1 (EC50 69.9 miromol x L(-1)). Hence, 1,2-diarylbenzimidazoles A6 and B3, and 1,6-diarylbenzimidazole B6 showed obvious potency against HIV-1 replication in MT-2 cell line with EC50 values of 15.33, 9.81 and 1.37 micromol x L(-1) respectively. All target compounds were synthesized commonly from substituted 2-nitroanilines by 1-3 steps under mild reaction conditions. Current studies provided preliminary SAR, thus indicating that 1,6-diaryl substitution on the benzimidazole ring would be a right direction for further modification. Furthermore, the docking studies demonstrated that B6 could fit well into the HIV-1 NNRTI binding pocket with a similar binding orientation and conformation to that of TMC278, a promising NNRTI candidate inclinical trial III, Therefore, active compound B6 could serve as a new starting point to develop a series of 1,6-diarylbenzimidazole derivatives as HIV-1 NNRTI agents with a novel skeleton.

[The research on accuracy of computer-assisted surgery].

The computer-assisted surgery system is a complex system. All of the errors can be attributed to the loss of correspondence between the world coordinate system in the operation room and the virtual world coordinate system obtained from the multi-model medical images. The system's accuracy is composed of the accuracy of the localizer and that of registration. In order to improve the system accuracy, we analyse most of the possible error sources. The accuracy of the localizer affects deeply the registration between the intra-operation and pre-operation data. The localizer is the most basic and important part for a computer-assisted surgery system. We give a comprehensive possible error source at the end of the paper.