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Prakasha Gowda, Thomas E Spratt
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a potent tobacco carcinogen that forms mutagenic DNA adducts including O(6)-methyl-2'-deoxyguanosine (O(6)-Me-dG), O(6)-[4-(3-pyridyl)-4-oxobut-1-yl]-dG (O6-POB-dG), O(2)-methylthymidine (O(2)-Me-dT), and O(2)-POB-dT. We evaluated the ability of human DNA polymerase ν to bypass this damage to evaluate the structural constraints on substrates for pol ν and to evaluate if there is kinetic evidence suggesting the in vivo activity of pol ν on tobacco-induced DNA damage...
October 14, 2016: Chemical Research in Toxicology
Sreekanth C Narayanapillai, Shang-Hsuan Lin, Pablo Leitzman, Pramod Upadhyaya, Carolyn J Baglole, Chengguo Xing
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a key carcinogen responsible for tobacco smoke-induced lung carcinogenesis. Among DNA damages caused by NNK and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), O6-methylguanine (O6-mG) is likely the most carcinogenic in A/J mice. Results of our previous studies showed that O6-mG and other NNAL-derived DNA damages were preferentially reduced in the lung of female A/J mice upon the dietary treatment with dihydromethysticin (DHM), a promising lung cancer chemopreventive agent from kava...
October 11, 2016: Chemical Research in Toxicology
Josa M Frischer, Christine Marosi, Adelheid Woehrer, Johannes A Hainfellner, Karin Ute Dieckmann, Helmut Eiter, Wei-Te Wang, Ammar Mallouhi, Adolf Ertl, Engelbert Knosp, Martin Filipits, Klaus Kitz, Brigitte Gatterbauer
BACKGROUND: We evaluated Gamma Knife radiosurgery (GKRS) as a treatment option for patients with recurrent glioblastoma. PATIENTS AND METHODS: 42 patients with histopathologically diagnosed recurrent grade IV tumor were treated with GKRS. All patients had undergone standard multimodal first-line treatment. The average time from diagnosis to GKRS was 17.0 months. The median target volume was 5.1 cm3. The median margin dose was 10 Gy and the median central dose 20 Gy...
October 8, 2016: Stereotactic and Functional Neurosurgery
Helena Guiset Miserachs, Daniela Donghi, Richard Börner, Silke Johannsen, Roland K O Sigel
RNA G-quadruplexes, as their well-studied DNA analogs, require the presence of cations to fold and remain stable. This is the first comprehensive study on the interaction of RNA quadruplexes with metal ions. We investigated the formation and stability of two highly conserved and biologically relevant RNA quadruplex-forming sequences (24nt-TERRA and 18nt-NRAS) in the presence of several monovalent and divalent metal ions, namely Li(+), Na(+), K(+), Rb(+), Cs(+), NH4(+), Mg(2+), Ca(2+), Sr(2+), and Ba(2+). Circular dichroism was used to probe the influence of these metal ions on the folded fraction of the parallel G-quadruplexes, and UV thermal melting experiments allowed to assess the relative stability of the structures in each cationic condition...
October 4, 2016: Journal of Biological Inorganic Chemistry: JBIC
Christina V Sathyanathan, B Jyothirmayi, Lakshmi R Sundaram, P A Abhinand, R Eswaramoorthy, K Mary Elizabeth Gnanambal
AIMS: This investigation is designed to evaluate the antibacterial efficiency of the noodle grass, Syringodium isoetifolium, which is commonly occurring in the Indian coastal waters. Also this study characterizes the active compound and predicts the mode of action, in silico. METHODS AND RESULTS: Human pathogenic bacteria were treated with crude metabolites of S. isoetifolium. The potent fraction, b was analyzed by UV/VIS, RP-HPLC, FT-IR, ESI-Mass, (1) H and (13) C NMRs and determined to be a hydrate of Pheophytin a [C55 H74 N4 O6 ]...
October 4, 2016: Journal of Applied Microbiology
Amritaj Patra, Qianqian Zhang, F Peter Guengerich, Martin Egli
O6-Methyl-2(prime)-deoxyguanosine (O6-MeG) is a ubiquitous DNA lesion, formed not only by xenobiotic carcinogens but also by the endogenous methylating agent S-adenosylmethionine. It can introduce mutations during DNA replication, with different DNA polymerases displaying different ratios of correct or incorrect incoporation opposite this nucleoside. Of the "translesion" Y-family human DNA polymerases (hpols), hpol η is most efficient in incorporating equal numbers of correct and incorrect C and T bases. However, the mechanistic basis for this specific yet indescriminate activity is not known...
September 30, 2016: Journal of Biological Chemistry
Taiichi Saito, Kazuhiko Sugiyama, Fusao Ikawa, Fumiyuki Yamasaki, Minoru Ishifuro, Takeshi Takayasu, Ryo Nosaka, Yoshihiro Muragaki, Takakazu Kawamata, Kaoru Kurisu
OBJECTIVE: The current standard treatment protocol for patients with newly diagnosed glioblastoma (GBM) includes surgery, radiotherapy, and concomitant and adjuvant temozolomide (TMZ). We hypothesized that the permeability surface area product (PS) from a perfusion CT (PCT) study is associated with sensitivity to TMZ. The aim of this study was to determine whether PS values were correlated with prognosis of GBM patients who received the standard treatment protocol. METHODS: This study included 36 patients with GBM that were newly diagnosed between October 2005 and September 2014 and who underwent preoperative PCT study and the standard treatment protocol...
September 27, 2016: World Neurosurgery
Mariia V Pavliuk, Edgar Mijangos, Valeriya G Makhankova, Vladimir N Kokozay, Sonja Pullen, Jia Liu, Jiefang Zhu, Stenbjörn Styring, Anders Thapper
The heterometallic complexes (NH4 )2 [Co(H2 O)6 ]2 [V10 O28 ]⋅4 H2 O (1) and (NH4 )2 [Co(H2 O)5 (β-HAla)]2 [V10 O28 ]⋅4 H2 O (2) have been synthesized and used for the preparation of mixed oxides as catalysts for water oxidation. Thermal decomposition of 1 and 2 at relatively low temperatures (<500 °C) leads to the formation of the solid mixed oxides CoV2 O6 /V2 O5 (3) and Co2 V2 O7 /V2 O5 (4). The complexes (1, 2) and heterogeneous materials (3, 4) act as catalysts for photoinduced water oxidation...
September 30, 2016: ChemSusChem
Man-Rong Li, Zheng Deng, Saul H Lapidus, Peter W Stephens, Carlo U Segre, Mark Croft, Robert Paria Sena, Joke Hadermann, David Walker, Martha Greenblatt
A novel 6H-type hexagonal perovskite Ba3(Cr0.97(1)Te0.03(1))2TeO9 was prepared at high pressure (6 GPa) and temperature (1773 K). Both transmission electron microscopy and synchrotron powder X-ray diffraction data demonstrate that Ba3(Cr0.97(1)Te0.03(1))2TeO9 crystallizes in P63/mmc with face-shared (Cr0.97(1)Te0.03(1))O6 octahedral pairs interconnected with TeO6 octahedra via corner-sharing. Structure analysis shows a mixed Cr(2+)/Cr(3+) valence state with ∼10% Cr(2+). The existence of Cr(2+) in Ba3(Cr(2+)0...
October 17, 2016: Inorganic Chemistry
Maria Etelvina Pinto-Fochi, Eloísa Zanin Pytlowanciv, Vanessa Reame, Alex Rafacho, Daniele Lisboa Ribeiro, Sebastião Roberto Taboga, Rejane M Góes
This study evaluated the impact of a high-fat diet (HFD) during different stages of the rat life, associated or not with maternal obesity, on the content of sex steroid hormones and the morphophysiology of Leydig cells. The following periods of development were examined: (O1) gestation, (O2) gestation and lactation, (O3) from weaning to adulthood, (O4) from lactation to adulthood, (O5) gestation to adulthood and (O6) after sexual maturation. The HFD contained 20% unsaturated fat while the control diet was 4% fat...
September 27, 2016: Reproduction: the Official Journal of the Society for the Study of Fertility
Sun Woo Kim, Zheng Deng, Zachary Fischer, Saul H Lapidus, Peter W Stephens, Man-Rong Li, Martha Greenblatt
New layered honeycomb tellurates, BiM(III)TeO6 (M = Cr, Mn, Fe) were synthesized and characterized. BiM(III)TeO6 (M = Cr, Fe) species crystallize in a trigonal space group, P3̅1c (No. 163), of edge-sharing M(3+)/Te(6+)O6 octahedra, which form honeycomb-like double layers in the ab plane with Bi(3+) cations located between the layers. Interestingly, the structure of BiMnTeO6 is similar to those of the Cr/Fe analogues, but with monoclinic space group, P21/c (No. 14), attributed to the strong Jahn-Teller distortion of Mn(3+) cations...
October 17, 2016: Inorganic Chemistry
Olivier Renier, Clément Falaise, Harrison Neal, Karoly Kozma, May Nyman
Uranyl polyoxometalate clusters are both fundamentally fascinating and potentially relevant to nuclear energy applications. With only ten years of development, there is still much to be discovered about heterometal derivatives and aqueous speciation and behavior. Herein, we show that it is possible to encapsulate the polyoxocations [Bi6 O8 ](2+) and [Pb8 O6 ](4+) in [(UO2 )(O2 )(OH)]24(24-) (denoted Bi@U24 and Pb@U24 ) in pure form and high yields despite the fact that under aqueous conditions, these compounds are stable on opposite ends of the pH scale...
October 17, 2016: Angewandte Chemie
Debmalya Bhattacharyya, Gayan Mirihana Arachchilage, Soumitra Basu
This review is focused on the structural and physicochemical aspects of metal cation coordination to G-Quadruplexes (GQ) and their effects on GQ stability and conformation. G-quadruplex structures are non-canonical secondary structures formed by both DNA and RNA. G-quadruplexes regulate a wide range of important biochemical processes. Besides the sequence requirements, the coordination of monovalent cations in the GQ is essential for its formation and determines the stability and polymorphism of GQ structures...
2016: Frontiers in Chemistry
Akihiro Imamura, Naomi Matsuzawa, Shizuo Sakai, Taro Udagawa, Shinya Nakashima, Hiromune Ando, Hideharu Ishida, Makoto Kiso
The origin of the high α(1,2-cis)-stereoselectivity in the reaction of galactosyl and galactosaminyl donors with a di-tert-butylsilylene (DTBS) group with several nucleophiles has been elucidated by means of experimental and computational approaches. DTBS overcomes any other cyclic protecting groups examined to date and the β(1,2-trans)-directing effect due to the neighboring participation by CO groups at C2. Requirements for the α(1,2-cis)-stereoselectivity are as follows: (1) generation of an oxocarbenium ion; (2) a galacto-type glycosyl donor with a cyclic protecting group bridging O4 and O6 to form a six-membered ring; (3) through-space electron donation from O4 and O6 into the empty p-orbital of the anomeric carbon to stabilize the oxocarbenium intermediate; (4) steric hindrance due to bulky alkyl substituents on the cyclic protecting group to prevent nucleophilic attack from the β-face; and (5) a 4,6-O-silylene structure...
October 7, 2016: Journal of Organic Chemistry
Tao Fu, Anup Sharmab, Fei Xie, Yanliang Liu, Kai Li, Weiwei Wan, Stephen B Baylin, Christopher L Wolfgang, Nita Ahuja
BACKGROUND: O6-methylguanine-DNA methyltransferase (MGMT) methylation status has not been extensively investigated in duodenal adenocarcinoma (DA). The aim of this study was to evaluate the MGMT methylation status and examine its possible prognostic value in patients with stage III DA. METHODS: Demographics, tumor characteristics and survival were available for 64 patients with stage III DA. MGMT methylation was detected by using MethyLight. A Cox proportional hazard model was built to predict survival, adjusted for clinicopathological characteristics and tumor molecular features, including the CpG island methylator phenotype (CIMP), microsatellite instability (MSI), and KRAS mutations...
2016: PloS One
Andrew J Knappenberger, Md Faiz Ahmad, Rajesh Viswanathan, Chris G Dealwis, Michael E Harris
Class I ribonucleotide reductase (RR) maintains balanced pools of deoxyribonucleotide substrates for DNA replication by converting ribonucleoside diphosphates (NDPs) to 2'-deoxyribonucleoside diphosphates (dNDPs). Binding of deoxynucleoside triphosphate (dNTP) effectors (ATP/dATP, dGTP, and dTTP) modulates the specificity of class I RR for CDP, UDP, ADP, and GDP substrates. Crystal structures of bacterial and eukaryotic RRs show that dNTP effectors and NDP substrates bind on either side of a flexible nine-amino acid loop (loop 2)...
October 3, 2016: Biochemistry
Qing Zhao, Min Liu, Jianhong Dai, Hongshan Deng, Yunyu Yin, Long Zhou, Junye Yang, Zhiwei Hu, Stefano Agrestini, Kai Chen, Eric Pellegrin, Manuel Valvidares, Lucie Nataf, François Baudelet, L H Tjeng, Yi-Feng Yang, Changqing Jin, Youwen Long
Pb2FeOsO6 was prepared for the first time by using high-pressure and high-temperature synthesis techniques. This compound crystallizes into a B-site-ordered double-perovskite structure with cubic symmetry Fm3̅m, where the Fe and Os atoms are orderly distributed with a rock-salt-type manner. Structure refinement shows an Fe-Os antisite occupancy of about 16.6%. Structural analysis and X-ray absorption spectroscopy both demonstrate the charge combination to be Pb2Fe(3+)Os(5+)O6. A long-range ferrimagnetic transition is found to occur at about 280 K due to antiferromagnetic interactions between the adjacent Fe(3+) and Os(5+) spins with a straight (180°) Fe-O-Os bond angle, as confirmed by X-ray magnetic circular-dichroism measurements...
October 3, 2016: Inorganic Chemistry
Qing Zhao, Jianbin Wang, Yong Lu, Yixin Li, Guangxin Liang, Jun Chen
Oxocarbon salts (M2 (CO)n ) prepared through one-pot proton exchange reactions with different metal ions (M=Li, Na, K) and frameworks (n=4, 5, 6) have been rationally designed and used as electrodes in rechargeable Li, Na, and K-ion batteries. The results show that M2 (CO)5 /M2 (CO)6 salts can insert two or four metal ions reversibly, while M2 (CO)4 shows less electrochemical activity. Especially, we discover that the K2 C6 O6 electrode enables ultrafast potassium-ion insertion/extraction with 212 mA h g(-1) at 0...
September 26, 2016: Angewandte Chemie
Johann-Martin Hempel, Sotirios Bisdas, Jens Schittenhelm, Cornelia Brendle, Benjamin Bender, Henk Wassmann, Marco Skardelly, Ghazaleh Tabatabai, Salvador Castaneda Vega, Ulrike Ernemann, Uwe Klose
The purpose of this study is to assess the diagnostic performance of diffusion kurtosis imaging (DKI) for in vivo molecular profiling of human glioma. Normalized mean kurtosis (MKn) and mean diffusivity (MDn) metrics from DKI were assessed in 50 patients with histopathologically confirmed glioma. The results were compared in regard to the WHO-based histological findings and molecular characteristics leading to integrated diagnosis (Haarlem Consensus): isocitrate-dehydrogenase (IDH1/2) mutation status, alpha-thalassemia/mental retardation syndrome X-linked (ATRX) expression, chromosome 1p/19q loss of heterozygosity (LOH), and O6-methylguanine DNA methyltransferase (MGMT) promoter methylation status...
September 7, 2016: Journal of Neuro-oncology
S G Creemers, P M van Koetsveld, E S R van den Dungen, E Korpershoek, F J van Kemenade, G J H Franssen, W W de Herder, R A Feelders, L J Hofland
CONTEXT: Treatment of patients with adrenocortical carcinomas (ACC) with mitotane and/or chemotherapy is often associated with toxicity and poor tumor response. New therapeutic options are urgently needed. OBJECTIVE: To evaluate the therapeutic possibilities of temozolomide (TMZ) in ACC cells and to assess the potential predictive role of the DNA repair gene O6-Methylguanine-DNA methyltransferase (MGMT) in adrenocortical tumors. METHODS: 3 human ACC cell lines and 8 primary ACC cultures were used to assess effects of TMZ in vitro...
September 7, 2016: Journal of Clinical Endocrinology and Metabolism
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