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Sacha Fop, Eve J Wildman, Janet M S Skakle, Clemens Ritter, Abbie C Mclaughlin
The electrical and structural properties of the series Ba3Mo1-xNb1+xO8.5-x/2 (x = 0.0, 0.1, 0.2, 0.3) have been determined. Ba3Mo1-xNb1+xO8.5-x/2 crystallizes in a hybrid of the 9R hexagonal perovskite and palmierite structures, in which (Mo/Nb)O4 and (Mo/Nb)O6 units coexist within the structure. Nb substitutes preferentially at the octahedral site so that the ratio of (Mo/Nb)O4 tetrahedra to (Mo/Nb)O6 octahedra decreases with increasing x resulting in a reduction in the magnitude of the ionic conductivity from 1...
August 17, 2017: Inorganic Chemistry
Katie A Wilson, Stacey D Wetmore
Although translesion synthesis (TLS) polymerases play key roles in replicating DNA that contains nucleobase addition products (adducts), there are many unknowns about their function. The present work gains indispensable structural insights from molecular dynamics simulations on the replication of O6-benzyl-guanine (Bz-dG) prior to bond formation during dCTP insertion opposite the adduct by Dpo4. When combined with previous X-ray crystal structures of the Bz-dG extension complex, molecular details are now available for each stage during a single TLS replication cycle for this carcinogenic lesion...
August 15, 2017: Chemical Research in Toxicology
Manohar Puppala, Sreekanth C Narayanapillai, Pablo Leitzman, Haifeng Sun, Pramod Upadhyaya, M Gerard O'Sullivan, Stephen S Hecht, Chengguo Xing
(+)-Dihydromethysticin was recently identified as a promising lung cancer chemopreventive agent while (+)-dihydrokavain was completely ineffective. A pilot in vivo structure-activity relationship (SAR) was explored, evaluating the efficacy of its analogs in blocking 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced short-term O6-methylguanine and long-term adenoma formation in the lung tissues in A/J mice. Both results revealed cohesive SARs, demonstrating that the methylenedioxy functional group in DHM is essential while the lactone functional group tolerates modifications...
August 14, 2017: Journal of Medicinal Chemistry
Zhor Senhaji Mouhri, Elliot Goodfellow, Bertrand Jean-Claude
BACKGROUND: Mutations of the DNA repair proteins BRCA1/2 are synthetically lethal with the DNA repair enzyme poly(ADP-ribose) polymerase (PARP), which when inhibited, leads to cell death due to the absence of compensatory DNA repair mechanism. The potency of PARP inhibitors has now been clinically proven. However, disappointingly, acquired resistance mediated by the reactivation of wild type BRCA1/2 has been reported. In order to improve their efficacy, trials are ongoing to explore their combinations with temozolomide (TMZ)...
August 11, 2017: BMC Cancer
Xuan-He Liu, Wei-Li Hu, Wen-Jie Jiang, Ya-Wen Yang, Shuai Niu, Bing Sun, Jing Wu, Jin-Song Hu
Metal-nitrogen coordination sites, M-Nx (M = Fe, Co, Ni, etc.), have shown great potential to replace platinum group materials as electrocatalysts for oxygen reduction reaction (ORR). However, the real active site in M-Nx is still vague to date due to their complicated structure and composition. It is therefore highly desirable but challenging to develop ORR catalysts with novel and clear active sites, which could meet the needs of comprehensive understanding of structure-function relationships and explore new cost-effective and efficient ORR electrocatalysts...
August 18, 2017: ACS Applied Materials & Interfaces
Karolina Schwendtner, Uwe Kolitsch
The crystal structures of hydrothermally synthesized aluminium dihydrogen arsenate(V) dihydrogen diarsenate(V), Al(H2AsO4)(H2As2O7), gallium dihydrogen arsenate(V) dihydrogen diarsenate(V), Ga(H2AsO4)(H2As2O7), and diindium bis[dihydrogen arsenate(V)] bis[dihydrogen diarsenate(V)], In2(H2AsO4)2(H2As2O7)2, were determined from single-crystal X-ray diffraction data collected at room temperature. The first two compounds are representatives of a novel sheet structure type, whereas the third compound crystallizes in a novel framework structure...
August 1, 2017: Acta Crystallographica. Section C, Structural Chemistry
Ishaq N Khan, Najeeb Ullah, Deema Hussein, Kulvinder S Saini
Recent investments in research associated with the discovery of specific tumor biomarkers important for efficient diagnosis and prognosis of the patients are beginning to bear fruit. Key biomarkers could potentially outweigh traditional radiological or pathological methods by enabling specificity of early detection, when coupled with tumor molecular profiling and clinical associations. Only few biomarkers are approved by regulatory authorities for Central Nervous System Tumors (CNSTs), despite the evaluation of a large number of CNST related markers during clinical trials...
July 31, 2017: Seminars in Cancer Biology
Mia D Sørensen, Rikke H Dahlrot, Henning B Boldt, Steinbjørn Hansen, Bjarne W Kristensen
AIMS: Glioblastomas are highly aggressive and treatment-resistant. Increasing evidence suggests that tumor-associated macrophages/microglia (TAMs) facilitate tumor progression by acquiring a M2-like phenotype. Our objective was to investigate the prognostic value of TAMs in gliomas using automated quantitative double immunofluorescence. METHODS: Samples from 240 patients with primary glioma were stained with antibodies against ionized calcium-binding adaptor molecule-1 (IBA-1) and CD204 to detect TAMs and M2-like TAMs...
August 2, 2017: Neuropathology and Applied Neurobiology
Katherine Baran, Mao Yang, Christopher P Dillon, Leona L Samson, Douglas R Green
In addition to promoting cell death and senescence, p53 also has important cellular survival functions. A mutant p53, lacking a proline-rich domain (p53(ΔP)), that is deficient in controlling both cell death and cell cycle arrest, was employed to determine the biological means by which p53 mediates survival upon DNA damage. While p53(ΔP) and p53(-/-) cells were equally resistant to many DNA damaging agents, p53(ΔP) cells showed an exquisite resistance to high doses of the alkylating agent Diazald (N-Methyl-N-(p-tolylsulfonyl)nitrosamide), as compared to cells completely deficient for p53 function...
July 28, 2017: Cell Death and Differentiation
Ewa Katzenellenbogen, Magdalena Staniszewska, Nina A Kocharova, Małgorzata Mieszała, Agnieszka Korzeniowska-Kowal, Sabina Górska, Yuriy A Knirel, Andrzej Gamian
BACKGROUND: Citrobacter strains are opportunistic pathogens often responsible for serious enteric as well as extra-intestinal diseases, and therefore the O-antigenic scheme, still in use in diagnostic identification, should be set for proper serotyping. The structures of more than 30 different Citrobacter O-antigens (O-polysaccharide chains of the lipopolysaccharides) of 43 Citrobacter O-serogroups have been elucidated so far. However, relationships between strains in several heterogeneous serogroups still need to be clarified by immunochemical studies...
July 27, 2017: BMC Microbiology
Jiapeng Leng, Yinsheng Wang
Quantification of DNA lesions constitutes one of the main tasks in toxicology and in assessing health risks accompanied with exposure to carcinogens. Tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) can undergo metabolic transformation to give a reactive intermediate that pyridyloxobutylates nucleobases and phosphate backbone of DNA. Here, we reported a highly sensitive method, relying on the use of nanoflow liquid chromatography-nanoelectrospray ionization-tandem mass spectrometry (nLC-nESI-MS/MS), for the simultaneous quantifications of O6-[4-(3-pyridyl)-4-oxobut-1-yl]-2-deoxyguanosine (O6-POBdG) as well as O2- and O4-[4-(3-pyridyl)-4-oxobut-1-yl]-thymidine (O2-POBdT and O4-POBdT)...
July 27, 2017: Analytical Chemistry
Sun Woo Kim, Zheng Deng, Shuang Yu, Haricharan Padmanabhan, Weiguo Zhang, Venkatraman Gopalan, Changqing Jin, Martha Greenblatt
A(II)GeTeO6 (A = Mn, Cd, Pb), new non-centrosymmetric (NCS) honeycomb-layered tellurates, were synthesized and characterized. A(II)GeTeO6 (A = Mn, Cd, Pb) crystallize in trigonal space group P312 (No. 149) of edge-sharing Ge(4+)O6 and Te(6+)O6 octahedra, which form honeycomb-like-layers in the ab-plane with A(II) (A = Mn, Cd, Pb) cations located between the layers. Their crystal structures are PbSb2O6-related, and the ordering of Ge(4+) and Te(6+) in octahedral environment breaks the inversion symmetry of the parent PbSb2O6 structure...
August 7, 2017: Inorganic Chemistry
R R Khusnutdinov, S V Boichuk
We studied the mechanisms of sensitivity of soft tissue sarcoma cells to alkylating agent temozolomide. The mechanisms of tumor cell sensitivity to temozolomide are complex and are determined by not only the level of O6-methylguanine-DNA-methyltransferase (MGTM) expression, but also activity of oncosuppressor protein p53. A-673 Ewing's sarcoma cells were found to be the most sensitive to temozolomide, whereas temozolomide-treated SK-LMS-1 leiomyosarcoma cells exhibited signs of cell aging.
June 2017: Bulletin of Experimental Biology and Medicine
Gulcin Tezcan, Berrin Tunca, Hilal Demirci, Ahmet Bekar, Mevlut Ozgur Taskapilioglu, Hasan Kocaeli, Unal Egeli, Gulsah Cecener, Sahsine Tolunay, Ozgur Vatan
Unmethylated O6-methylguanine-DNA-methyltransferase (MGMT) promoter leads to Temozolomide (TMZ) resistance in most of the glioblastoma multiforme (GBM) patients. We previously investigated the synergistic effect of Olea europaea leaf extract (OLE) on TMZ cytotoxicity through modulating microRNA expression. To date, knowledge about the effect of OLE on MGMT methylation is insufficient. The aim of the current study was to evaluate the potential modulating effect of OLE on the TMZ response of GBM tumors through MGMT methylation...
July 18, 2017: Nutrition and Cancer
Dominik Weber, Manop Huber, Tatiana E Gorelik, Artem M Abakumov, Nils Becker, Oliver Niehaus, Christian Schwickert, Sean P Culver, Hans Boysen, Anatoliy Senyshyn, Rainer Pöttgen, Richard Dronskowski, Thorsten Ressler, Ute Kolb, Martin Lerch
Blue-colored molybdenum oxide nitrides of the Mo2(O,N,□)5 type were synthesized by direct nitridation of commercially available molybdenum trioxide with a mixture of gaseous ammonia and oxygen. Chemical composition, crystal structure, and stability of the obtained and hitherto unknown compounds are studied extensively. The average oxidation state of +5 for molybdenum is proven by Mo K near-edge X-ray absorption spectroscopy; the magnetic behavior is in agreement with compounds exhibiting Mo(V)O6 units. The new materials are stable up to ∼773 K in an inert gas atmosphere...
August 7, 2017: Inorganic Chemistry
Olesya I Naumenko, Han Zheng, Sof'ya N Senchenkova, Hong Wang, Qun Li, Alexander S Shashkov, Jianping Wang, Yuriy A Knirel, Yanwen Xiong
The O-specific polysaccharides (OPSs) called O-antigens were obtained by mild acid degradation of the lipopolysaccharides of Escherichia albertii serotypes O3, O4, O6, and O7 and studied by sugar analysis along with 1D and 2D (1)H and (13)C NMR spectroscopy. The following structure was established for the OPS of E. albertii O4, which, to our knowledge, is unique among known bacterial polysaccharide structures: →2)-α-l-Rhap-(1 → 2)-α-l-Fucp-(1 → 2)-β-d-Galp-(1 → 3)-α-d-GalpNAc-(1 → 3)-β-d-GlcpNAc-(1→ The OPS structure of the strain of E...
June 17, 2017: Carbohydrate Research
Claudia Kessler, Alessa Pardo, Mehmet K Tur, Stefan Gattenlöhner, Rainer Fischer, Katharina Kolberg, Stefan Barth
PURPOSE: Despite great progress in the diagnosis and treatment of localized prostate cancer (PCa), there remains a need for new diagnostic markers that can accurately distinguish indolent and aggressive variants. One promising approach is the antibody-based targeting of prostate stem cell antigen (PSCA), which is frequently overexpressed in PCa. Here, we show the construction of a molecular imaging probe comprising a humanized scFv fragment recognizing PSCA genetically fused to an engineered version of the human DNA repair enzyme O6-alkylguanine-DNA alkyltransferase (AGT), the SNAP-tag, enabling specific covalent coupling to various fluorophores for diagnosis of PCa...
June 30, 2017: Journal of Cancer Research and Clinical Oncology
Yu Nakagawa, Hikaru Sasaki, Kentaro Ohara, Taketo Ezaki, Masahiro Toda, Takayuki Ohira, Takeshi Kawase, Kazunari Yoshida
OBJECTIVE: The purpose of this study was to clarify the clinical and molecular characteristics associated with long-term survival in patients with glioblastoma. METHODS: We analyzed the characteristics of 96 glioblastoma patients. Long-term survivors (LTSs) were classified into moderate LTSs (mLTSs), who survived more than 3 years, and LTSs survived more than 5 years, and compared with short-term survivors (STSs). Clinical and molecular factors were investigated...
June 27, 2017: World Neurosurgery
H Y Huang, Z Y Chen, R-P Wang, F M F de Groot, W B Wu, J Okamoto, A Chainani, A Singh, Z-Y Li, J-S Zhou, H-T Jeng, G Y Guo, Je-Geun Park, L H Tjeng, C T Chen, D J Huang
The first known magnetic mineral, magnetite, has unusual properties, which have fascinated mankind for centuries; it undergoes the Verwey transition around 120 K with an abrupt change in structure and electrical conductivity. The mechanism of the Verwey transition, however, remains contentious. Here we use resonant inelastic X-ray scattering over a wide temperature range across the Verwey transition to identify and separate out the magnetic excitations derived from nominal Fe(2+) and Fe(3+) states. Comparison of the experimental results with crystal-field multiplet calculations shows that the spin-orbital dd excitons of the Fe(2+) sites arise from a tetragonal Jahn-Teller active polaronic distortion of the Fe(2+)O6 octahedra...
June 29, 2017: Nature Communications
Katie A Wilson, Kariann G Szemethy, Stacey D Wetmore
The present work uses DFT calculations to characterize the conformational and hydrogen-bonding properties of O6-[4-oxo-4-(3-pyridyl)butyl]guanine (POB-G), a DNA adduct caused by tobacco. POB-G is found to adopt many isoenergetic conformations that allow for discrete interactions between the bulky moiety and the adducted G and/or pairing base. The calculated structure and stability of the hydrogen-bonded pairs between the Watson-Crick or Hoogsteen face of POB-G and the canonical DNA nucleobases fully rationalize the previously reported mutational spectra...
September 2017: Biophysical Chemistry
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