2,663 research outputs found

    Determination of Nucleopolyhedrovirus’ Taxonomic Position

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    To date , over 78 genomes of nucleopolyhedroviruses (NPVs) have been sequenced and deposited in NCBI. How to define a new virus from the infected larvae in the field is usually the first question. Two NPV strains, which were isolated from casuarina moth (L. xylina) and golden birdwing larvae (Troides aeacus), respectively, displayed the same question. Due to the identity of polyhedrin (polh) sequences of these two isolates to that of Lymantria dispar MNPV and Bombyx mori NPV, they are named LdMNPV-like virus and TraeNPV, provisionally. To further clarify the relationships of LdMNPV-like virus and TraeNPV to closely related NPVs, Kimura 2-parameter (K-2-P) analysis was performed. Apparently, the results of K-2-P analysis that showed LdMNPV-like virus is an LdMNPV isolate, while TraeNPV had an ambiguous relationship to BmNPV. Otherwise, MaviNPV, which is a mini-AcMNPV, also exhibited a different story by K-2-P analysis. Since K-2-P analysis could not cover all species determination issues, therefore, TraeNPV needs to be sequenced for defining its taxonomic position. For this purpose, different genomic sequencing technologies and bioinformatic analysis approaches will be discussed. We anticipated that these applications will help to exam nucleotide information of unknown species and give an insight and facilitate to this issue

    A novel randomly textured phosphor structure for highly efficient white light-emitting diodes

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    We have successfully demonstrated the enhanced luminous flux and lumen efficiency in white light-emitting diodes by the randomly textured phosphor structure. The textured phosphor structure was fabricated by a simple imprinting technique, which does not need an expensive dry-etching machine or a complex patterned definition. The textured phosphor structure increases luminous flux by 5.4% and 2.5% at a driving current of 120 mA, compared with the flat phosphor and half-spherical lens structures, respectively. The increment was due to the scattering of textured surface and also the phosphor particles, leading to the enhancement of utilization efficiency of blue light. Furthermore, the textured phosphor structure has a larger view angle at the full width at half maximum (87°) than the reference LEDs

    Preparation and Bioactivity Properties of a Novel Composite Membrane of Fructose Mediated β

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    A novel composite membrane of β-tricalcium pyrophosphate (β-TCP) and fructose- (F-) mediated chitosan/poly(ethylene glycol) (CS/PEG) was prepared by thermally induced phase separation technique. The prepared composite membranes were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical property, swelling, degradation, and cytotoxicity of the composite membranes were evaluated in vitro with respect to its potential for use as biodegradable guided tissue regeneration (GTR) membrane. In vitro degradation tests showed the composite membrane with a controllable degradation rate when changing the β-TCP content. The incorporation of β-TCP granules also caused a significant enhancement of tensile strength. When β-TCP content is controlled to 50 wt%, homogeneous composite membranes with well mechanical property and enzymatic degradation rate can be obtained. Cytotoxicity assay demonstrates that the composite membranes were nontoxic and had very good cell compatibility. Most importantly, the release of calcium ions and glucosamine from the composite membranes was proved to increase the cell proliferation of NIH3T3. The results of this study have indicated that this novel F-β-TCP/CS/PEG composite can be a suitable material for GTR applications

    ortho-Quinone tanshinones directly inhibit telomerase through an oxidative mechanism mediated by hydrogen peroxide

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    The tanshinone natural products possess a variety of pharmacological properties including anti-bacterial, anti-inflammatory, anti-oxidant, and anti-neoplastic activity. The molecular basis of these effects, however, remains largely unknown. In the present study, we explored the direct effect of tanshinones on the enzyme telomerase. Telomerase is up-regulated in the majority of cancer cells and is essential for their survival, making it a potential anti-cancer drug target. We found that the ortho-quinone tanshinone II-A inhibits telomerase in a time- and DTT-dependent fashion, and the hydrogen peroxide scavenger catalase protected telomerase from inactivation. These findings demonstrate that ortho-quinone containing tanshinones can inhibit telomerase owing to their ability to generate reactive oxygen species. The results also provide evidence that telomerase is directly and negatively regulated by reactive oxygen species

    Altaicalarins A−D, Cytotoxic Bisabolane Sesquiterpenes from Ligularia altaica

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    Four new bisabolane sesquiterpenes, altaicalarins A–D (1–4) and three known analogues (5–7) were isolated from the roots and rhizomes of Ligularia altaica. The structures were elucidated by spectroscopic methods including 2D NMR techniques, and the structure of 1 was confirmed by single-crystal X-ray diffraction. The isolated compounds were also evaluated for cytotoxic activity against human lung carcinoma (A-549), human breast adenocarcinoma (MCF-7), epidermoid carcinoma of the nasopharynx (KB), and vincristine-resistant nasopharyngeal (KBVIN) cell lines, and 1 was found to show significant cytotoxicity with EC50 values of 3.4, 0.8, 1.0, and 0.9 µg/mL, respectively

    Antitumor Agents. 266. Design, Synthesis, and Biological Evaluation of Novel 2-(Furan-2-yl)naphthalen-1-ol Derivatives as Potent and Selective Antibreast Cancer Agents

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    In a continuing study, we explored how the individual rings in neo-tanshinlactone (1) influence its potent and selective in vitro anti-breast cancer activity. Accordingly, we discovered a novel class of anti-breast cancer agents, 2-(furan-2-yl) naphthalen-1-ol derivatives, based on an active C-ring opened model compound 5. Further optimization led to 18 and 21, which showed decreased cytotoxic potency, but better selectivity than neo-tanshinlactone analog 2. Interestingly, compound 20 showed broad cytotoxicity against human cancer cell lines

    Synthesis, biological evaluation, and physicochemical property assessment of 4-substituted 2-phenylaminoquinazolines as Mer tyrosine kinase inhibitors

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    Current results identified 4-substituted 2-phenylaminoquinazoline compounds as novel Mer tyrosine kinase (Mer TK) inhibitors with a new scaffold. Twenty-one 2,4-disubstituted quinazolines (series 4-7) were designed, synthesized, and evaluated against Mer TK and a panel of human tumor cell lines aimed at exploring new Mer TK inhibitors as novel potential antitumor agents. A new lead, 4b, was discovered with a good balance between high potency (IC50 0.68μM) in the Mer TK assay and antiproliferative activity against MV4-11 (GI50 8.54μM), as well as other human tumor cell lines (GI50<20μM), and a desirable druglike property profile with low logP value (2.54) and high aqueous solubility (95.6μg/mL). Molecular modeling elucidated an expected binding mode of 4b with Mer TK and necessary interactions between them, thus supporting the hypothesis that Mer TK might be a biologic target of this kind of new active compound

    Synthesis and anti-HIV activity of 2′-deoxy-2′-fluoro-4′-C-ethynyl nucleoside analogs

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    Based on the favorable antiviral profiles of 4′-substituted nucleosides, novel 1-(2′-deoxy-2′-fluoro-4′-C-ethynyl-β-D-arabinofuranosyl)-uracil (1a), -thymine (1b), and – cytosine (2) analogues were synthesized. Compounds 1b and 2 exhibited potent anti-HIV-1 activity with IC50 values of 86 and 1.34 nM, respectively, without significant cytotoxicity. Compound 2 was 35-fold more potent than AZT against wild-type virus, and also retained nanomolar antiviral activity against resistant strains, NL4-3(K101E) and RTMDR. Thus, 2 merits further development as a novel NRTI drug

    Discovery of novel 5-fluoro-N 2 ,N 4 -diphenylpyrimidine-2,4-diamines as potent inhibitors against CDK2 and CDK9

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    Novel 5-fluoro-pyrimidine derivatives have been designed, synthesized and evaluated as potential CDK inhibitors as well as antitumor and anti-HIV agents

    Songaricalarins A–E, Cytotoxic Oplopane Sesquiterpenes from Ligularia songarica

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    Five new highly oxygenated oplopane sesquiterpenes, songaricalarins A–E (1–5), and two known analogues (6 and 7) were isolated from the roots and rhizomes of Ligularia songarica. Their structures and configurations were elucidated by spectroscopic methods, including 2D-NMR techniques, and the structure of 1 was confirmed by single-crystal X-ray diffraction. All compounds were evaluated for in vitro cytotoxic activity against cultured A-549, MCF-7, KB, and KBVIN cells, and 4 exhibited cytotoxicity with EC50 values of 4.9, 0.8, 3.4, and 3.2 µg/mL, respectively
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