| 1. |
- Lele, Duan, et al.
(författare)
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Carbene-pyridine chelating 2Fe2S hydrogenase model complexes as highly active catalysts for the electrochemical reduction of protons from weak acid (HOAc)
- 2007
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; :13, s. 1277-1283
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Tidskriftsartikel (refereegranskat)abstract
- Two asymmetrically disubstituted diiron complexes (mu-pdt)[Fe(CO)(3)][Fe(CO)(eta(2)-L)] (L = 1-methyl-3-(2-pyridyl)imidazol-2-ylidene (NHCMePy), 2; 1,3-bis(2-picolyl) imidazol-2-ylidene (NHCdiPic), 4) and a mono-substituted diiron complex (mu-pdt)[Fe(CO)(3)][Fe(CO)(2)(NHCdiPic)] (3) were prepared as biomimetic models of the Fe-only hydrogenase active site. X-Ray studies show that the NHCMePy and NHCdiPic ligands in 2 and 4 each coordinate to the single iron atom as NHC-Py chelating ligands in two basal positions and the NHCdiPic ligand of complex 3 lies in an apical position as a monodentate ligand. The large ranges of the highest and the lowest nu(CO) frequencies of 2 and 4 reflect that the relatively uneven electron density on the two iron atoms of the 2Fe2S model complexes 2 and 4 is as that observed for mono-substituted diiron complexes of good donor ligands. The cyclic voltammograms and the electrochemical proton reduction by 2 and 3 were studied in the presence of HOAc to evaluate the effect of asymmetrical substitution of strong donor ligands on the redox properties of the iron atoms and on the electrocatalytic activity for proton reduction.
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| 2. |
- Li, Fie, et al.
(författare)
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Synthesis, structure and catalytic property of an iron(II) complex with an N4O2 ligand for alkane oxidation
- 2006
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Ingår i: Wuji huaxue xuebao. - 1001-4861. ; 22:10, s. 1899-1904
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Tidskriftsartikel (refereegranskat)abstract
- Two iron(II) complexes [Fe(tpdoen)](FeCl4)Cl (2, tpdoen=NN-bis(2-pyridylmethoxyethyl)-N-(2-pyridylmethyl)amine) and [Fe(tpdoen)](ClO4)(2) (3) with an N4O2 ligand containing two potentially pi-coordinate oxygen atoms were synthesized as functional models of non-heme iron oxygenases. The X-ray crystal structure analysis corroborated that complex 3 possesses a significantly distorted six-coordinate pseudooctahedral configuration, in which all six heteroatoms (N4O2) coordinate to the iron center. The catalytic property of complex 3 for alkane oxidation were explored using H2O2, TBHP and mCPBA as oxidants in the presence of excess substrates under mild conditions. When cyclohexane oxidation process was monitored by UV-Vis spectra using H2O2 as oxidant at 0 degrees C, a short-life band appeared at ca 550 nm, which is attributed to the in-situ Fe(III)-OOH species.
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| 3. |
- Li, Xueqiang, et al.
(författare)
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Noncovalent assembly of a metalloporphyrin and an iron hydrogenase active-site model : Photo-induced electron transfer and hydrogen generation
- 2008
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207 .- 1089-5647. ; 112:27, s. 8198-8202
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Tidskriftsartikel (refereegranskat)abstract
- A noncovalent assembly of a pyridyl-functionalized hydrogenase active-site model complex and zinc tetraphenylporphyrin has been obtained and characterized. Upon light irradiation, fluorescence quenching by electron transfer was observed from the singlet excited state of the porphyrin to the diiron center, and the mechanism was verified by fluorescence lifetime and transient absorption spectroscopic measurements. In contrast to molecular dyads linked by covalent bonds, the assembled system was designed to avoid charge recombination via complex dissociation after photo-induced electron transfer. Visible light-driven hydrogen generation was observed from this self-assembled system. The assembling strategy employed in this study has the potential to be used for any other hydrogenase models in the future.
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| 4. |
- Lin, Chen, et al.
(författare)
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Concomitant use of Ad5/35 chimeric oncolytic adenovirus with TRAIL gene and taxol produces synergistic cytotoxicity in gastric cancer cells
- 2009
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Ingår i: Cancer Letters. - : Elsevier BV. - 1872-7980 .- 0304-3835. ; 284:2, s. 141-148
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Tidskriftsartikel (refereegranskat)abstract
- Chimeric adenoviral vectors possessing fiber derived from human adenovirus subgroup B (Ad35) have been developed for their high infection efficiency in cell types which are refractory to adenovirus serotype 5 (Subgroup C) The present study constructed an E1B-deleted chimeric oncolytic adenovirus, SG235-TRAIL, which carries a human TRAIL gene expression cassette and whose fiber shaft and knob domains are from serotype AM. It was found that SG235-TRAIL preferentially replicated in gastric cancer cell lines, SGC-7901 and BGC-823 compared to in normal human fibroblast BJ cells. Also, when compared with a replication-deficient chimeric vector Ad5/35-TRAIL, SG235-TRAIL mediated a higher level of the transgene expression via viral replication in the cancer cells. Further, because of the more efficient cell-entry and infection, SG235-TRAIL induced stronger cell apoptosis than the Ad5 CRAD vector, ZD55-TRAIL In addition, SG235-TRAIL in combination with the chemotherapeutic drug, taxol, produced a synergistic cytotoxic effect in cancer cells in vitro without causing significant toxicity to normal cells. In the gastric tumor xenograft mouse model, intratumoral SG235-TRAIL injection produced a significant antitumor effect 14 days after treatment. Pathological examination demonstrated TRAIL expression and associated apoptosis in majority of SG235-TRAIL-treated tumor cells. These results suggest that SG235-TRAIL is a potential novel, efficient anti-cancer agent, and in combination with taxol, it would be even more useful with considerably low toxic side effects. (C) 2009 Elsevier Ireland Ltd. All rights reserved.
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| 5. |
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| 7. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 8. |
- Stoeckius, Marlon, et al.
(författare)
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Large-scale sorting of C. elegans embryos reveals the dynamics of small RNA expression.
- 2009
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Ingår i: Nature Methods. - : Nature Publishing Group. - 1548-7091 .- 1548-7105. ; 6:10
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Tidskriftsartikel (refereegranskat)abstract
- Caenorhabditis elegans is one of the most prominent model systems for embryogenesis, but collecting many precisely staged embryos has been impractical. Thus, early C. elegans embryogenesis has not been amenable to most high-throughput genomics or biochemistry assays. To overcome this problem, we devised a method to collect staged C. elegans embryos by fluorescence-activated cell sorting (eFACS). In a proof-of-principle experiment, we found that a single eFACS run routinely yielded tens of thousands of almost perfectly staged 1-cell stage embryos. As the earliest embryonic events are driven by posttranscriptional regulation, we combined eFACS with second-generation sequencing to profile the embryonic expression of small, noncoding RNAs. We discovered complex and orchestrated changes in the expression between and within almost all classes of small RNAs, including microRNAs and 26G-RNAs, during embryogenesis.
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| 9. |
- Su, Changqing, et al.
(författare)
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Gene-Viral Cancer Therapy Using Dual-Regulated Oncolytic Adenovirus with Antiangiogenesis Gene for Increased Efficacy.
- 2008
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Ingår i: Molecular Cancer Research. - 1557-3125. ; 6, s. 568-575
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Tidskriftsartikel (refereegranskat)abstract
- Conditionally replicative adenovirus (CRAD) represents a promising approach for cancer therapy. Several CRADs controlled by the human telomerase reverse transcriptase promoter have been developed. However, because of their replicative capacity, the importance of cancer specificity for CRADs needs to be further emphasized. In this study, we have developed a novel dual-regulated CRAD, CNHK500-mE, which has its E1a and E1b gene controlled by the human telomerase reverse transcriptase promoter and the hypoxia response element, respectively. It also carries a mouse endostatin expression cassette controlled by the cytomegalovirus promoter. These properties allow for increased cancer cell targeting specificity and decreased adverse side effects. We showed that CNHK500-mE preferentially replicated in cancer cells. Compared with a replication-defective vector carrying the same endostatin expression cassette, CNHK500-mE-mediated transgene expression level was markedly increased via viral replication within cancer cells. In the nasopharyngeal tumor xenograft model, CNHK500-mE injection resulted in antitumor efficacy at day 7 after therapy. Three weeks later, it led to significant inhibition of xenograft tumor growth due to the combined effects of viral oncolytic therapy and antiangiogenesis gene therapy. Pathologic examination showed that most cancer cells were positive for adenoviral capsid protein and for apoptotic terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling in the CNHK500-mE-treated tumor tissues, and the microvessels in these tumor tissues were diminished in quantity and abnormal in morphology. These results suggest that, as a potential cancer therapeutic agent, the CNHK500-mE is endowed with higher specificity to cancer cells and low cytotoxicity to normal cells. (Mol Cancer Res 2008;6(4):OF1-8).
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