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https://www.readbyqxmd.com/read/28806726/replication-fork-slowing-and-stalling-are-distinct-checkpoint-independent-consequences-of-replicating-damaged-dna
#1
Divya Ramalingam Iyer, Nicholas Rhind
In response to DNA damage during S phase, cells slow DNA replication. This slowing is orchestrated by the intra-S checkpoint and involves inhibition of origin firing and reduction of replication fork speed. Slowing of replication allows for tolerance of DNA damage and suppresses genomic instability. Although the mechanisms of origin inhibition by the intra-S checkpoint are understood, major questions remain about how the checkpoint regulates replication forks: Does the checkpoint regulate the rate of fork progression? Does the checkpoint affect all forks, or only those encountering damage? Does the checkpoint facilitate the replication of polymerase-blocking lesions? To address these questions, we have analyzed the checkpoint in the fission yeast Schizosaccharomyces pombe using a single-molecule DNA combing assay, which allows us to unambiguously separate the contribution of origin and fork regulation towards replication slowing, and allows us to investigate the behavior of individual forks...
August 14, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28806711/the-potential-of-an-automated-system-to-identify-the-upper-limb-component-of-a-controlled-sitting-posture
#2
María B Sánchez, Ian Loram, John Darby, Paul Holmes, Penelope B Butler
Full trunk control in sitting is demonstrated only when the head-trunk are aligned and upper limbs remain free of contact from mechanical support. These components represent a Controlled Kinetic Chain and can be evaluated in people with neuromotor disability using the Segmental Assessment of Trunk Control (SATCo) when a therapist provides manual trunk support at different segmental levels. However, the SATCo, as with other clinical assessments of control, is subjective. The SATCo was translated to objective rules relating the position of the hands and elbows to the head-trunk and then tested to determine the extent to which this automated objective method replicated the clinical judgement...
August 8, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28806677/influence-of-the-residue-from-an-iron-mining-dam-in-the-growth-of-two-macrophyte-species
#3
F Bottino, J A M Milan, M B Cunha-Santino, I Bianchini
On November 5th, 2015 the worst environmental disaster in Brazil spilled 60 million m(3) of iron mining residue into Gualaxo do Norte River (Minas Gerais State), an affluent of the highest River Basin of the Brazilian Southeast (Doce River Basin), reaching the Atlantic Ocean. To assess the impact of the iron residue on the aquatic plant metabolism, we performed macrophyte growth experiments under controlled light and temperature conditions using two species (Egeria densa and Chara sp.). The plants' growth data were fitted in a kinetic model to obtain the biomass yields (K) and growth rates (μ)...
August 8, 2017: Chemosphere
https://www.readbyqxmd.com/read/28806675/biotransformation-of-nsaids-by-pig-liver-microsomes-in%C3%A2-vitro-kinetics-metabolites-identification-and-toxicity-prediction
#4
Liyun Ma, Xiaojing Mao, Xiao Sun, Li Xu
Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most frequently used pharmaceuticals in animals. In the current study, the biotransformation of five NSAIDs by pig liver microsomes (PLMs) was studied. The pseudo-first-order kinetics mode was obtained for the metabolization of the studied NSAIDs by PLMs in vitro. The metabolites were identified by high performance liquid chromatography with a high-resolution LTQ-Orbitrap mass spectrometry. The hydroxylation of benzene was confirmed to be the dominating metabolic pathway...
August 8, 2017: Chemosphere
https://www.readbyqxmd.com/read/28806523/production-of-concentrated-pickering-emulsions-with-narrow-size-distributions-using-stirred-cell-membrane-emulsification
#5
Mohamed Soyeb Manga, David W York
Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity...
August 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28806521/determination-of-caspase-3-activity-and-its-inhibition-constant-by-combination-of-fluorescence-correlation-spectroscopy-with-a-microwell-chip
#6
Di Su, Xiaocai Hu, Chaoqing Dong, Jicun Ren
Caspase-3 is a key enzyme executing apoptosis during ontogenesis and homeostasis of multicellular organisms, and is a very important and potential drug target in treatment of apoptosis disturbance. So far, no commercial drugs for caspase-3 are available, and it is urgently necessitated to develop an effective method for caspase-3 activity assay and its inhibitor screening. In this paper, we propose a new method for determination of caspase-3 activity and its inhibition constant by combining single molecule fluorescence correlation spectroscopy (FCS) with a microwell chip...
August 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28806505/co4n-nanowires-noble-metal-free-peroxidase-mimetic-with-excellent-salt-and-temperature-resistant-abilities
#7
Yu-Zhen Li, Tong-Tong Li, Wei Chen, Yan-Yan Song
Compared to natural enzymes, nanomaterial-based artificial enzymes have attracted immense attention because of their high stability and cost-effectiveness. In this study, cobalt nitride (Co4N) as a noble-metal-free artificial enzyme exhibiting highly intrinsic peroxidase-like activity and good stability was reported. Kinetic studies revealed that the resultant Co4N nanowires (NWs) exhibited a stronger affinity for 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 than HRP. Compared to Co3O4 NWs, Co4N NWs exhibited highly improved catalytic activities, with H2O2 exhibiting an apparent Km approximately 2 orders of magnitude less than that of Co3O4...
August 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28806503/identification-of-the-dimer-exchange-interface-of-the-bacterial-dna-damage-response-protein-umud
#8
David A Murison, Rebecca C Timson, Bilyana Koleva, Michael Ordazzo, Penny J Beuning
The Escherichia coli SOS response, an induced DNA damage response pathway, confers survival on bacterial cells by providing accurate repair mechanisms as well as the potentially mutagenic pathway translesion synthesis (TLS). The umuD gene products are upregulated after DNA damage and play roles in both non-mutagenic and mutagenic aspects of the SOS response. Full-length UmuD is expressed as a homodimer of 139-amino-acid subunits, which eventually cleaves its N-terminal 24 amino acids to form UmuD'. The cleavage product, UmuD', together with UmuC, form the Y-family polymerase DNA Pol V (UmuD'2C) capable of performing TLS...
August 14, 2017: Biochemistry
https://www.readbyqxmd.com/read/28806292/-optimization-and-standardization-of-the-immunodeficient-mouse-model-for-assessing-fat-grafting-outcomes
#9
Lauren E Kokai, Taraneh L Jones, Russell Silowash, Brian Theisen, Gabriella DiBernardo, Andrew Lu, Bowen Yi, Kacey G Marra, J Peter Rubin
BACKGROUND: Animal models are often used to assess interventions that might improve fat grafting outcomes, however, there is great variability in the models. We sought to determine the predictive value of the immunocompromised mouse model for fat grafting so that experiments could be standardized and optimized. METHODS: Human lipoaspirate injections at different volumes and time points were assessed in a nude mouse model and compared with control injections of non-viable fat...
August 3, 2017: Plastic and Reconstructive Surgery
https://www.readbyqxmd.com/read/28806086/role-of-electrostatics-in-protein-rna-binding-the-global-vs-the-local-energy-landscape
#10
Zhaleh Ghaemi, Irisbel Guzman, David Gnutt, Zaida Luthey-Schulten, Martin Gruebele
U1A protein - stem loop 2 RNA association is a basic step in the assembly of the spliceosomal U1 small nuclear ribonucleoprotein. Long-range electrostatic interactions due to the positive charge of U1A are thought to provide high binding affinity for the negatively charged RNA. Short range interactions, such as hydrogen bonds and contacts between RNA bases and protein side chains, favor a specific binding site. Here, we propose that electrostatic interactions are as important as local contacts in biasing the protein-RNA energy landscape towards a specific binding site...
August 14, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28806081/chlorination-kinetics-of-11-nor-9-carboxy-%C3%AE-9-tetrahydrocannabinol-effects-of-ph-and-humic-acid
#11
Allison L Mackie, Yuri Park, Graham A Gagnon
The main psychoactive compound in marijuana, Δ9-tetrahydrocannabinol (THC), and its metabolites are emerging organic contaminants that have been detected in waste and surface waters. As legalization of marijuana for medical and recreational use continues, the effects of increased use and potency of marijuana on water and wastewater treatment processes and the environment should be considered. This study examined degradation kinetics of the main urinary metabolite of THC, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) with chlorine...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806080/dissociative-photoionization-of-the-elusive-vinoxy-radical
#12
Jonathan D Adams, Preston G Scrape, Shih-Huang Lee, Laurie J Butler
These experiments report the dissociative photoionization of vinoxy radicals to m/z = 15 and 29. In a crossed laser-molecular beam scattering apparatus, we induce C-Cl bond fission in 2-chloroacetaldehyde by photoexcitation at 157 nm. Our velocity measurements, combined with conservation of angular momentum, show that 21% of the C-Cl photofission events form vinoxy radicals that are stable to subsequent dissociation to CH3 + CO or H + ketene. Photoionization of these stable vinoxy radicals, identified by their velocities, which are momentum-matched with the higher-kinetic-energy Cl atom photofragments, shows that the vinoxy radicals dissociatively photoionize to give signal at m/z = 15 and 29...
August 14, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28806076/structure-affinity-relationships-and-structure-kinetics-relationships-of-pyrido-2-1-f-purine-2-4-dione-derivatives-as-human-adenosine-a3-receptor-antagonists
#13
Lizi Xia, Wessel A C Burger, Jacobus P D van Veldhoven, Boaz J Kuiper, Tirsa T van Duijl, Eelke B Lenselink, Ellen Paasman, Laura H Heitman, Adriaan P IJzerman
We expanded on a series of pyrido[2,1-f]purine-2,4-dione derivatives as human adenosine A3 receptor (hA3R) antagonists to determine their kinetic profiles and affinities. Many compounds showed high affinities and a diverse range of kinetic profiles. We found hA3R antagonists with very short residence time at the receptor (RT of 2.2 min for 5) and much longer RTs (e.g. 376 min for 27, or 391 min for 31). Two representative antagonists (5 and 27) were tested in [(35)S]GTPγS binding assays, and their RTs appeared correlated to their (in)surmountable antagonism...
August 14, 2017: Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28806073/transformation-among-aromatic-iodinated-disinfection-byproducts-in-the-presence-of-monochloramine-from-monoiodophenol-to-triiodophenol-and-diiodonitrophenol
#14
Tingting Gong, Yuxian Tao, Xiangru Zhang, Shaoyang Hu, Jinbao Yin, Qiming Xian, Jian Ma, Bin Xu
Aromatic iodinated disinfection byproducts (DBPs) are a newly identified category of highly toxic DBPs. Among the identified aromatic iodinated DBPs, 2,4,6-triiodophenol and 2,6-diiodo-4-nitro- phenol have shown relatively widespread occurrence and high toxicity. In this study, we found that 4-iodophenol underwent transformation to form 2,4,6-triiodophenol and 2,6-diiodo-4-nitrophenol in the presence of monochloramine. The transformation pathways were investigated, the decomposition kinetics of 4-iodophenol and the formation of 2,4,6-triiodophenol and 2,6-diiodo-4-nitrophenol were studied, the factors affecting the transformation were examined, the toxicity change during the transformation was evaluated, and the occurrence of the proposed transformation pathways during chloramination of source water was verified...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28806069/oxidation-kinetics-of-bromophenols-by-nonradical-activation-of-peroxydisulfate-in-the-presence-of-carbon-nanotube-and-formation-of-brominated-polymeric-products
#15
Chao-Ting Guan, Jin Jiang, Cong-Wei Luo, Jun Ma, Su-Yan Pang, Yang Zhou, Yi Yang
This work demonstrated that bromophenols (BrPs) could be readily oxidized by peroxydisulfate (PDS) activated by a commercial carbon nanotube (CNT), while furfuryl alcohol (a chemical probe for singlet oxygen (1O2)) was quite refractory. Results obtained by radical quenching experiments, electron paramagnetic resonance spectroscopy, and Fourier transform infrared spectroscopy further confirmed the involvement of nonradical PDS-CNT complexes rather than 1O2. Bicarbonate and chloride ion exhibited negligible impacts on BrPs degradation by the PDS/CNT system, while a significant inhibitory effect was observed for natural organic matter...
August 14, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28805994/monitoring-photosynthetic-activity-in-microalgal-cells-by-raman-spectroscopy-with-deuterium-oxide-as-a-tracking-probe
#16
Yusuke Yonamine, Yuta Suzuki, Takuro Ito, Yoshiko Miura, Keisuke Goda, Yasuyuki Ozeki, Yu Hoshino
Microalgae offer great potential for biofuel production, but high photosynthetic activity is demanded for practical realization of microalgal biofuels. To this end, it is essential to evaluate the photosynthetic activity of single microalgal cells in a heterogeneous population. In this study, we present a method for monitoring photosynthetic activity of microalgae (in particular Euglena gracilis, a microalgal species of unicellular, photosynthetic, flagellate protists as our model organism) at single-cell resolution by Raman spectroscopy with deuterium from deuterium oxide (D2O) as a tracking probe...
August 14, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28805981/noncompetitive-inhibition-of-human-cyp2c9-in%C3%A2-vitro-by-a-commercial-rhodiola-rosea-product
#17
Ole Kristian Forstrønen Thu, Olav Spigset, Bent Hellum
A commercial Rhodiola rosea (R. rosea) product has previously demonstrated CYP2C9 inhibition in humans. The purpose of this study was to provide in vitro inhibitory data for this particular interaction and to classify the mechanism of the interaction. Another aim was to examine the in vitro influence of ethanol on the CYP2C9 activity. Human CYP2C9 (wild type) isolated from a baculovirus-infected cell system was incubated with 0.8 μmol/L losartan for 20 min. Sulfaphenazole was used as a positive control...
August 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28805876/few-layered-mos2-c-with-expanding-d-spacing-as-a-high-performance-anode-for-sodium-ion-batteries
#18
Peng Zhang, Furong Qin, Lei Zou, Mengran Wang, Kai Zhang, Yanqing Lai, Jie Li
Sodium-ion batteries (SIBs) show great potential as alternative energy storage devices for next generation energy storage systems due to the deficiency of lithium resources. MoS2 is a promising anode material for SIBs due to its high theoretical sodium storage capability and large interspace for accommodating sodium ions with a larger ionic radius than lithium ions. However, bulk MoS2 exhibits a sluggish kinetics for the intercalation-deintercalation of sodium ions and large volume expansion, which result in poor cyclability and rate performance...
August 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/28805875/frequency-selective-electrokinetic-enrichment-of-biomolecules-in-physiological-media-based-on-electrical-double-layer-polarization
#19
Ali Rohani, Bankim J Sanghavi, Armita Salahi, Kuo-Tang Liao, Chia-Fu Chou, Nathan S Swami
Proteomic biomarkers of interest to the early diagnosis of diseases and infections are present at trace levels versus interfering species. Hence, their selective enrichment is needed within bio-assays for speeding binding kinetics with receptors and for reducing signal interferences. While DC fields can separate biomolecules based on their electrokinetic mobilities, they are unable to selectively enrich biomarkers versus interfering species, which may possess like-charges. We present the utilization of AC electrokinetics to enable frequency-selective enrichment of nanocolloidal biomolecules, based on the characteristic time constant for polarization of their electrical double-layer, since surface conduction in their ion cloud depends on colloidal size, shape and surface charge...
August 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/28805858/optimal-hydrogen-storage-in-sodium-substituted-lithium-fullerides
#20
Mattia Gaboardi, Chiara Milanese, Giacomo Magnani, Alessandro Girella, Daniele Pontiroli, Pacifico Cofrancesco, Amedeo Marini, Mauro Riccò
Through the substitution of Li with Na in Li6C60, we synthesized a series of mixed alkali cluster intercalated fullerides, NaxLi6-xC60. These compounds share lattices of Na6C60 and Li6C60 with a cubic parameter linearly dependent on x. H2 absorption and desorption were studied by means of charge/discharge kinetic measurements and coupled calorimetric-manometric evaluation. By varying the stoichiometry, we found the best compromise among the absorption rate, temperature and amount of hydrogen for x = 0.5 and 1...
August 14, 2017: Physical Chemistry Chemical Physics: PCCP
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