26 research outputs found
Genotyping the hepatitis B virus with a fragment of the HBV DNA polymerase gene in Shenyang, China
The hepatitis B virus (HBV) has been classified into eight genotypes (A-H) based on intergenotypic divergence of at least 8% in the complete nucleotide sequence or more than 4% in the S gene. To facilitate the investigation of the relationship between the efficacy of drug treatment and the mutation with specific genotype of HBV, we have established a new genotyping strategy based on a fragment of the HBV DNA polymerase gene. Pairwise sequence and phylogenetic analyses were performed using CLUSTAL V (DNASTAR) on the eight (A-H) standard full-length nucleotide sequences of HBV DNA from GenBank (NCBI) and the corresponding semi-nested PCR products from the HBV DNA polymerase gene. The differences in the semi-nested PCR fragments of the polymerase genes among genotypes A through F were greater than 4%, which is consistent with the intergenotypic divergence of at least 4% in HBV DNA S gene sequences. Genotyping using the semi-nested PCR products of the DNA polymerase genes revealed that only genotypes B, C, and D were present in the 50 cases, from Shenyang, China, with a distribution of 11 cases (22%), 25 cases (50%), and 14 cases (28%) respectively. These results demonstrate that our new genotyping method utilizing a fragment of the HBV DNA polymerase gene is valid and can be employed as a general genotyping strategy in areas with prevalent HBV genotypes A through F. In Shenyang, China, genotypes C, B, and D were identified with this new genotyping method, and genotype C was demonstrated to be the dominant genotype
The Hepatitis B Virus Ribonuclease H Is Sensitive to Inhibitors of the Human Immunodeficiency Virus Ribonuclease H and Integrase Enzymes
Nucleos(t)ide analog therapy blocks DNA synthesis by the hepatitis B virus (HBV) reverse transcriptase and can control the infection, but treatment is life-long and has high costs and unpredictable long-term side effects. The profound suppression of HBV by the nucleos(t)ide analogs and their ability to cure some patients indicates that they can push HBV to the brink of extinction. Consequently, more patients could be cured by suppressing HBV replication further using a new drug in combination with the nucleos(t)ide analogs. The HBV ribonuclease H (RNAseH) is a logical drug target because it is the second of only two viral enzymes that are essential for viral replication, but it has not been exploited, primarily because it is very difficult to produce active enzyme. To address this difficulty, we expressed HBV genotype D and H RNAseHs in E. coli and enriched the enzymes by nickel-affinity chromatography. HBV RNAseH activity in the enriched lysates was characterized in preparation for drug screening. Twenty-one candidate HBV RNAseH inhibitors were identified using chemical structure-activity analyses based on inhibitors of the HIV RNAseH and integrase. Twelve anti-RNAseH and anti-integrase compounds inhibited the HBV RNAseH at 10 μM, the best compounds had low micromolar IC50 values against the RNAseH, and one compound inhibited HBV replication in tissue culture at 10 μM. Recombinant HBV genotype D RNAseH was more sensitive to inhibition than genotype H. This study demonstrates that recombinant HBV RNAseH suitable for low-throughput antiviral drug screening has been produced. The high percentage of compounds developed against the HIV RNAseH and integrase that were active against the HBV RNAseH indicates that the extensive drug design efforts against these HIV enzymes can guide anti-HBV RNAseH drug discovery. Finally, differential inhibition of HBV genotype D and H RNAseHs indicates that viral genetic variability will be a factor during drug development. © 2013 Tavis et al
PHOTOINDUCED ELECTRON-TRANSFER (PET) IN ORGANIC-SYNTHESIS - [3+2)-TYPE CYCLOADDITION, CYCLIZATION AND C-C BOND-CLEAVAGE REACTIONS
ALBRECHT E, AVERDUNG J, BISCHOF EW, et al. PHOTOINDUCED ELECTRON-TRANSFER (PET) IN ORGANIC-SYNTHESIS - [3+2)-TYPE CYCLOADDITION, CYCLIZATION AND C-C BOND-CLEAVAGE REACTIONS. Journal of Photochemistry and Photobiology A Chemistry. 1994;82(1-3):219-232.An area of growing interest, in organic photochemistry in particular, involves the use of light to induce an electron transfer from a donor (D) to an acceptor (A) molecule, designated photoinduced electron transfer (PET). Excitation of A or D leads to well-defined changes in their redox properties, i.e. A (D) becomes a stronger acceptor (donor). In general, the feasibility of producing radical ions can be predicted using the well-known Weller equation and, moreover, polar solvents and salts effects support their formation. Following a brief introduction, we focus on the synthetic applications of PET, and discuss [3+2] cycloadditions, reductive and oxidative cyclizations and C-C bond cleavage reactions. The PET ring cleavage of azirines results in the formation of 2-azaallenyl radical cations which may be trapped by dipolarophiles to give heterocyclic compounds. Using this method, we have developed a new route to heterophanes. Porphyrins can also be prepared by this procedure. Further studies aim ot reveal the scope and limitations of these new reactions. Radical cations and radical anions can attack pi bonds within the same molecule. Depending on the reaction conditions chosen to generate the radical ions, five- or six-membered ring systems can be obtained. Under PET reductive conditions, radical anions arise which preferentially form five-membered ring molecules (Baldwin rule). However, using PET oxidative conditions, radical cations are generated which preferentially form six-membered ring molecules due to their electrophilic character. In addition, we have developed a new reductive C-C bond cleavage reaction with annular cyclopropanes and cyclobutanes and have applied this method to a new short synthesis of the hirsutene ring system
Photoinduced cycloadditions and cyclizations. Mechanistic studies and synthetic applications
Mattay J, Albrecht E, Fagnoni M, et al. Photoinduced cycloadditions and cyclizations. Mechanistic studies and synthetic applications. JOURNAL OF INFORMATION RECORDING. 1996;23(1-2):23-29.Synthetic applications and mechanistic studies from three areas of photoinduced cycloadditions and cyclizations are reported: First it is shown that unsaturated silyl enol ethers preferentially cyclisize in a 6-endo mode via their photochemically generated radical cations. In the following chapter we discuss fragmentation-cyclization reactions of unsaturated alpha-cyclopropyl ketones by photoinduced electron transfer leading to polycyclic compounds. Finally a kinetic and theoretical study of [2+3] cycloadditions of nitrile ylides generated from 2H-azirines is presented
Fluorometric determination of homovanillic acid in the presence of other acid metabolites of catecholamines
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Results of the 2011 UIS pilot data collection of innovation statistics
The relationship between innovation and economic development is widely acknowledged. Innovation is a key element in the growth of output and productivity, and therefore crucial for poverty alleviation. While research and experimental development (R&D) plays a vital role in the innovation process, many of the related activities rely on highly-skilled workers, interactions with other firms and public research institutions, as well as an organizational structure that is conducive to learning and exploiting knowledge.
These factors should be taken into account by policymakers. To this end, data are required to better understand innovation and its relation to economic growth, as well as to provide indicators for benchmarking national performance.
Over the last few decades, work has been undertaken to establish analytical frameworks and guidelines for innovation studies. Efforts to standardize innovation definitions and indicators came to the forefront with the publication of the first version of the Oslo Manual (OM) by the Organisation for Economic Co-operation and Development (OECD) in 1992. The manual pushed the measurement of innovation as a process, fostering the collection of comparable innovation indicators since its first edition. The UNESCO Institute for Statistics (UIS) is striving to increase the availability of timely, accurate and policy-relevant statistics in the field of science, technology and innovation (STI) through the development of a database of cross-nationally comparable innovation statistics. To this end, the UIS launched a pilot data collection of innovation statistics in 2011 in order to prepare for the global data collection which will be launched in 2013. The pilot data collection was based on the definitions of the third edition of the Oslo Manual, covering four types of innovation in the business sector. Data were collected for manufacturing, services and total economic activities covered by each national innovation survey. However, this report focuses exclusively on cross-nationally comparable data for the manufacturing industry. It should be noted that there are certain limitations in comparisons between countries due to differences in the methodological procedures of the national innovation surveys. The pilot data collection sought to gather aggregate data from the most recent national innovation surveys in 19 selected countries. Countries were asked to complete the pilot questionnaire using grossed up 2 results of their national innovation surveys. The following 12 countries participated in the pilot data collection: Brazil, China, Colombia, Egypt, Ghana, Indonesia, Israel, Malaysia, the Philippines, the Russian Federation, South Africa and Uruguay. Eurostat has led the way in sustaining the production of internationally comparable data on innovation in enterprises through its Community Innovation Surveys (CIS). Based on the CIS, Eurostat produces innovation statistics for member states and candidate countries of the European Union, Iceland and Norway, which are frequently used for comparison in national innovation survey reports. Therefore, in order to enhance interpretation of the UIS pilot results, whenever possible, this paper compares the data collected with Eurostat's CIS3 results from 2006 and 2008.