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https://www.readbyqxmd.com/read/28102691/thermodynamic-and-kinetic-stabilities-of-g-quadruplexes-in-apolar-solvents
#1
Elham Fadaei, Miguel Martín-Arroyo, Mohsen Tafazzoli, David González-Rodríguez
In contrast to more polar media, G-quadruplex assembly reveals remarkably high thermodynamic and kinetic stability in toluene solutions. Depending on the substituents installed at the lipophilic guanosine, either a dodecamer or an octamer complex is formed in the presence of K(+) or Na(+) salts that resist conditions of high dilution and elevated temperatures without exhibiting significant dissociation. Moreover, kinetic exchange between complexed and uncomplexed G is slow enough in NMR to monitor G-quadruplex formation along a day time scale...
January 19, 2017: Organic Letters
https://www.readbyqxmd.com/read/28102507/-44-sc-psma-617-for-radiotheragnostics-in-tandem-with-177-lu-psma-617-preclinical-investigations-in-comparison-with-68-ga-psma-11-and-68-ga-psma-617
#2
Christoph A Umbricht, Martina Benešová, Raffaella M Schmid, Andreas Türler, Roger Schibli, Nicholas P van der Meulen, Cristina Müller
BACKGROUND: The targeting of the prostate-specific membrane antigen (PSMA) is of particular interest for radiotheragnostic purposes of prostate cancer. Radiolabeled PSMA-617, a 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-functionalized PSMA ligand, revealed favorable kinetics with high tumor uptake, enabling its successful application for PET imaging ((68)Ga) and radionuclide therapy ((177)Lu) in the clinics. In this study, PSMA-617 was labeled with cyclotron-produced (44)Sc (T 1/2 = 4...
December 2017: EJNMMI Research
https://www.readbyqxmd.com/read/28102317/time-resolved-neutron-scattering-provides-new-insight-into-protein-substrate-processing-by-a-aaa-unfoldase
#3
Ziad Ibrahim, Anne Martel, Martine Moulin, Henry S Kim, Michael Härtlein, Bruno Franzetti, Frank Gabel
We present a combination of small-angle neutron scattering, deuterium labelling and contrast variation, temperature activation and fluorescence spectroscopy as a novel approach to obtain time-resolved, structural data individually from macromolecular complexes and their substrates during active biochemical reactions. The approach allowed us to monitor the mechanical unfolding of a green fluorescent protein model substrate by the archaeal AAA+ PAN unfoldase on the sub-minute time scale. Concomitant with the unfolding of its substrate, the PAN complex underwent an energy-dependent transition from a relaxed to a contracted conformation, followed by a slower expansion to its initial state at the end of the reaction...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28098838/role-of-udp-glucuronosyltransferase-1a1-in-the-metabolism-and-pharmacokinetics-of-silymarin-flavonolignans-in-patients-with-hcv-and-nafld
#4
Ying Xie, Sonia R Miranda, Janelle M Hoskins, Roy L Hawke
Silymarin is the most commonly used herbal medicine by patients with chronic liver disease. Silymarin flavonolignans undergo rapid first-pass metabolism primarily by glucuronidation. The aims of this investigation were: (1) to determine the association of UGT1A1*28 polymorphism with the area under the plasma concentration-time curves (AUCs) for silybin A (SA) and silybin B (SB); (2) to evaluate the effect of UGT1A1*28 polymorphism on the profile of flavonolignan glucuronide conjugates found in the plasma; and (3) to investigate the role of UGT1A1 enzyme kinetics on the pharmacokinetics of SA and SB...
January 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28098460/sulfate-mediated-end-to-end-assembly-of-gold-nanorods
#5
Seyyed Mohammad Hossein Abtahi, Nathan D Burrows, Fred A Idesis, Catherine J Murphy, Navid B Saleh, Peter J Vikesland
There is interest in the controlled aggregation of gold nanorods (GNRs) for the production of extended nanoassemblies. Prior studies have relied upon chemical modification of the GNR surface to achieve a desired final aggregate structure. Herein, we illustrate that control of electrolyte composition can facilitate end-to-end assembly of cetyltrimethylammonium bromide (CTAB) coated GNRs. By adjusting either the sulfate anion concentration or the exposure time it is possible to connect GNRs in chain-like assemblies...
January 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28097900/structure-activity-relationships-of-fraxamoside-as-an-unusual-xanthine-oxidase-inhibitor
#6
Rosa Maria Vitale, Lina Antenucci, Margherita Gavagnin, Gennaro Raimo, Pietro Amodeo
Fraxamoside, a macrocyclic secoiridoid glucoside featuring a hydroxytyrosol group, was recently identified as a xanthine oxidase inhibitor (XOI) comparable in potency in vitro to the standard antigout drug allopurinol. However, this activity and its considerably higher value than its derivatives oleuropein, oleoside 11-methyl ester, and hydroxytyrosol are not explained by structure-activity relationships (SARs) of known XOIs. To exclude allosteric mechanisms, we first determined the inhibition kinetic of fraxamoside...
December 2017: Journal of Enzyme Inhibition and Medicinal Chemistry
https://www.readbyqxmd.com/read/28096460/occupancy-of-the-zinc-binding-site-by-transition-metals-decreases-the-substrate-affinity-of-the-human-dopamine-transporter-by-an-allosteric-mechanism
#7
Yang Li, Felix P Mayer, Peter S Hasenhuetl, Verena Burtscher, Klaus Schicker, Harald H Sitte, Michael Freissmuth, Walter Sandtner
The human dopamine transporter (DAT) has a tetrahedral Zn(2+)-binding site. Zn(2+)-binding sites are also recognized by other first row transition metals. Excessive accumulation of manganese or of copper can lead to Parkinsonism due to dopamine deficiency. Accordingly, we examined the effect of Mn(2+), Co(2+), Ni(2+) and Cu(2+)on transport-associated currents through DAT and DAT-H193K, a mutant with a disrupted Zn(2+)-binding site. All transition metals - but Mn(2+) - modulated the transport cycle of wild type DAT with affinities in the low µM range...
January 17, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28096399/antiviral-screening-identifies-adenosine-analogs-targeting-the-endogenous-dsrna-leishmania-rna-virus-1-lrv1-pathogenicity-factor
#8
F Matthew Kuhlmann, John I Robinson, Gregory R Bluemling, Catherine Ronet, Nicolas Fasel, Stephen M Beverley
The endogenous double-stranded RNA (dsRNA) virus Leishmaniavirus (LRV1) has been implicated as a pathogenicity factor for leishmaniasis in rodent models and human disease, and associated with drug-treatment failures in Leishmania braziliensis and Leishmania guyanensis infections. Thus, methods targeting LRV1 could have therapeutic benefit. Here we screened a panel of antivirals for parasite and LRV1 inhibition, focusing on nucleoside analogs to capitalize on the highly active salvage pathways of Leishmania, which are purine auxotrophs...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28089499/the-stability-of-gadolinium-based-contrast-agents-in-human-serum-a-reanalysis-of-literature-data-and-association-with-clinical-outcomes
#9
John P Prybylski, Richard C Semelka, Michael Jay
PURPOSE: To reanalyze literature data of gadolinium (Gd)-based contrast agents (GBCAs) in plasma with a kinetic model of dissociation to provide a comprehensive assessment of equilibrium conditions for linear GBCAs. METHODS: Data for the release of Gd from GBCAs in human serum was extracted from a previous report in the literature and fit to a kinetic dissociation/association model. The conditional stabilities (logKcond) and percent intact over time were calculated using the model rate constants...
January 9, 2017: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/28088678/three-dimensional-lumbar-segment-movement-characteristics-during-paediatric-cerebral-palsy-gait
#10
D Kiernan, A Malone, T O'Brien, C K Simms
Kinematic analysis of the trunk during cerebral palsy (CP) gait has been well described. In contrast, movement of the lumbar spine is generally ignored. This is most likely due to the complex nature of the spine. As an alternative to using complex sensor protocols, this study modelled the lumbar region as a single segment and investigated characteristic patterns of movement during CP gait. In addition, the impact of functional level of impairment and the relationship with lower lumbar spinal loading were examined...
January 3, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28087672/elimination-of-sucrose-transport-and-hydrolysis-in-saccharomyces-cerevisiae-a-platform-strain-for-engineering-sucrose-metabolism
#11
Wesley Leoricy Marques, Robert Mans, Eko Roy Marella, Rosa Lorizolla Cordeiro, Marcel van den Broek, Jean-Marc G Daran, Jack T Pronk, Andreas K Gombert, Antonius J A van Maris
Many relevant options to improve efficacy and kinetics of sucrose metabolism in Saccharomyces cerevisiae and, thereby, the economics of sucrose-based processes, remain to be investigated. An essential first step is to identify all native sucrose-hydrolysing enzymes and sucrose transporters in this yeast, including those that can be activated by suppressor mutations in sucrose-negative strains. A strain in which all known sucrose-transporter genes (MAL11, MAL21, MAL31, MPH2, MPH3) were deleted did not grow on sucrose after 2 months of incubation...
January 12, 2017: FEMS Yeast Research
https://www.readbyqxmd.com/read/28077604/the-mitochondrial-dna-content-of-cumulus-granulosa-cells-is-linked-to-embryo-quality
#12
V Desquiret-Dumas, A Clément, V Seegers, L Boucret, V Ferré-L'Hotellier, P E Bouet, P Descamps, V Procaccio, P Reynier, P May-Panloup
STUDY QUESTION: Could the mitochondrial DNA (mtDNA) content of cumulus granulosa cells (CGCs) be related to oocyte competence? SUMMARY ANSWER: The quality of embryos obtained during IVF procedures appears to be linked to mtDNA copy numbers in the CGCs. WHAT IS KNOWN ALREADY: Oocyte quality is linked to oocyte mtDNA content in the human and other species, and the mtDNA copy number of the oocyte is related to that of the corresponding CGCs. Moreover, the quantification of CGC mtDNA has recently been proposed as a biomarker of embryo viability...
January 6, 2017: Human Reproduction
https://www.readbyqxmd.com/read/28068764/topochemical-azide-alkyne-cycloaddition-reaction-in-gels-size-tunable-synthesis-of-triazole-linked-polypeptides
#13
Baiju P Krishnan, Kana M Sureshan
Though topochemical reactions are attractive, the difficulty associated with crystallization such as low yield, unsuitability for large scale synthesis etc warranted the exploitation of other self-assembled media for topochemical reactions. We synthesized a dipeptide gelator decorated with azide and alkyne at its termini, N3-Ala-Val-NHCH2-C≡CH, which is designed to self-assemble through intermolecular hydrogen bonds to β-sheets thereby placing the azide and alkyne motifs at proximity. As anticipated, this peptide forms gels in organic solvents and water via hydrogen-bonded β-sheet assembly as evidenced from IR spectroscopy and PXRD profiling...
January 10, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28068088/a-200-mev-uphill-thermodynamic-landscape-for-radical-transport-in-escherichia-coli-ribonucleotide-reductase-determined-using-fluorotyrosine-substituted-enzymes
#14
Kanchana R Ravichandran, Alexander T Taguchi, Yifeng Wei, Cecilia Tommos, Daniel G Nocera, JoAnne Stubbe
Escherichia coli class Ia ribonucleotide reductase (RNR) converts ribonucleotides to deoxynucleotides. A diferric-tyrosyl radical (Y122•) in one subunit (β2) generates a transient thiyl radical in another subunit (α2) via long-range radical transport (RT) through aromatic amino acid residues (Y122 ⇆ [W48] ⇆ Y356 in β2 to Y731 ⇆ Y730 ⇆ C439 in α2). Equilibration of Y356•, Y731•, and Y730• was recently observed using site specifically incorporated unnatural tyrosine analogs; however, equilibration between Y122• and Y356• has not been detected...
October 19, 2016: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28067435/mr-imaging-findings-in-molecular-subtypes-of-breast-cancer-according-to-birads-system
#15
Lidia Navarro Vilar, Salvador Pascual Alandete Germán, Rosana Medina García, Esther Blanc García, Natalia Camarasa Lillo, José Vilar Samper
To evaluate magnetic resonance imaging (MRI) findings, according to Breast Imaging-Reporting and Data System (BI-RADS), and to relate them with molecular subtypes of breast cancer. The MRI findings were reviewed retrospectively in 201 women diagnosed of invasive breast cancer confirmed by surgery and were compared with the molecular subtypes. Following the BI-RADS, MRI findings included disease type, size, enhancement, morphology and contrast kinetics. In mass-like lesion types were studied shape, margin and enhancement, and in nonmass-like lesion types, distribution modifiers and internal enhancement...
January 9, 2017: Breast Journal
https://www.readbyqxmd.com/read/28065637/the-steroid-metabolite-16-%C3%AE-oh-androstenedione-generated-by-cyp21a2-serves-as-a-substrate-for-cyp19a1
#16
J Neunzig, M Milhim, L Schiffer, Y Khatri, J Zapp, A Sánchez-Guijo, M F Hartmann, S A Wudy, R Bernhardt
The 21-hydroxylase (CYP21A2) is a steroidogenic enzyme crucial for the synthesis of mineralo- and glucocorticoids. It is described to convert progesterone as well as 17-OH-progesterone, through a hydroxylation at position C21, into 11-deoxycorticosterone (DOC) and 11-deoxycortisol (RSS), respectively. In this study we unraveled CYP21A2 to have a broader steroid substrate spectrum than assumed. Utilizing a reconstituted in vitro system, consisting of purified human CYP21A2 and human cytochrome P450 reductase (CPR) we demonstrated that CYP21A2 is capable to metabolize DOC, RSS, androstenedione (A4) and testosterone (T)...
January 5, 2017: Journal of Steroid Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28063337/laser-assisted-atom-probe-tomography-of-ti-tin-films-deposited-on-si
#17
N A Sanford, P T Blanchard, R White, M R Vissers, D R Diercks, A V Davydov, D P Pappas
Laser-assisted atom probe tomography (L-APT) was used to examine superconducting TiN/Ti/TiN trilayer films with nominal respective thicknesses of 5/5/5 (nm). Such materials are of interest for applications that require large arrays of microwave kinetic inductance detectors. The trilayers were deposited on Si substrates by reactive sputtering. Electron energy loss microscopy performed in a scanning transmission electron microscope (STEM/EELS) was used to corroborate the L-APT results and establish the overall thicknesses of the trilayers...
December 21, 2016: Micron: the International Research and Review Journal for Microscopy
https://www.readbyqxmd.com/read/28062560/the-amyloid-phenomenon-and-its-links-with-human-disease
#18
Christopher M Dobson
The ability of normally soluble proteins to convert into amyloid fibrils is now recognized to be a generic phenomenon. The overall cross-β architecture of the core elements of such structures is closely similar for different amino acid sequences, as this architecture is dominated by interactions associated with the common polypeptide main chain. In contrast, the multiplicity of complex and intricate structures of the functional states of proteins is dictated by specific interactions involving the variable side chains, the sequence of which is unique to a given protein...
January 6, 2017: Cold Spring Harbor Perspectives in Biology
https://www.readbyqxmd.com/read/28060871/a-neonatal-murine-model-of-mrsa-pneumonia
#19
Elizabeth A Fitzpatrick, Dahui You, Bishwas Shrestha, David Siefker, Vivek S Patel, Nikki Yadav, Sridhar Jaligama, Stephania A Cormier
Pneumonia due to methicillin-resistant Staphylococcus aureus (MRSA) is a significant cause of morbidity and mortality in infants particularly following lower respiratory tract viral infections such as Respiratory Syncytial Virus (RSV). However, the mechanisms by which co-infection of infants by MRSA and RSV cause increased lung pathology are unknown. Because the infant immune system is qualitatively and quantitatively different from adults we developed a model of infant MRSA pneumonia which will allow us to investigate the effects of RSV co-infection on disease severity...
2017: PloS One
https://www.readbyqxmd.com/read/28060508/an-exploration-of-the-singlet-o2-oxidation-of-8-oxoguanine-by-guided-ion-beam-scattering-and-density-functional-theory-changes-of-reaction-intermediates-energetics-and-kinetics-upon-ionization-and-hydration
#20
Yan Sun, Wenchao Lu, Jianbo Liu
8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is one of the most common DNA lesions resulting from reactive oxygen species and ionizing radiation, and is involved in mutagenesis, carcinogenesis and cell death. Notably, 8-oxodGuo is more reactive toward singlet (a(1)Δg) O2 than the undamaged guanosine, and the lesions arising from the secondary oxidation of 8-oxodGuo are more mutagenic. Herein the (1)O2 oxidation of free base 8-oxoguanine (8-oxoG) was investigated at different initial conditions including protonated [8-oxoG + H](+), deprotonated [8-oxoG - H](-) and their monohydrates...
January 6, 2017: Journal of Physical Chemistry. B
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