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https://www.readbyqxmd.com/read/28813456/a-simple-molecular-mechanism-explains-multiple-patterns-of-cell-size-regulation
#1
Morgan Delarue, Daniel Weissman, Oskar Hallatschek
Increasingly accurate and massive data have recently shed light on the fundamental question of how cells maintain a stable size trajectory as they progress through the cell cycle. Microbes seem to use strategies ranging from a pure sizer, where the end of a given phase is triggered when the cell reaches a critical size, to pure adder, where the cell adds a constant size during a phase. Yet the biological origins of the observed spectrum of behavior remain elusive. We analyze a molecular size-control mechanism, based on experimental data from the yeast S...
2017: PloS One
https://www.readbyqxmd.com/read/28813421/stromal-r-spondin-orchestrates-gastric-epithelial-stem-cells-and-gland-homeostasis
#2
Michael Sigal, Catriona Y Logan, Marta Kapalczynska, Hans-Joachim Mollenkopf, Hilmar Berger, Bertram Wiedenmann, Roeland Nusse, Manuel R Amieva, Thomas F Meyer
The constant regeneration of stomach epithelium is driven by long-lived stem cells, but the mechanism that regulates their turnover is not well understood. We have recently found that the gastric pathogen Helicobacter pylori can activate gastric stem cells and increase epithelial turnover, while Wnt signalling is known to be important for stem cell identity and epithelial regeneration in several tissues. Here we find that antral Wnt signalling, marked by the classic Wnt target gene Axin2, is limited to the base and lower isthmus of gastric glands, where the stem cells reside...
August 16, 2017: Nature
https://www.readbyqxmd.com/read/28812878/nanomechanical-imaging-of-the-diffusion-of-fullerene-into-conjugated-polymer
#3
Dong Wang, Ken Nakajima, Feng Liu, Shaowei Shi, Thomas P Russell
The large Young's modulus difference between chemically modified fullerene (PCBM) and a conjugated polymer was used to nanomechanically map the diffusion of PCBM into PTB7, a high efficiency low band gap conjugated polymer. The sharp tip in nanomechanical atomic force microscopy (AFM) ensures a high-resolution nanomechanical characterization of the diffusion front, with the intrinsic benefits of revealing the mechanical properties of the mixtures. Localized structure changes induced by diffusion were investigated by grazing incidence x-ray diffraction methods...
August 16, 2017: ACS Nano
https://www.readbyqxmd.com/read/28812234/temperature-dependence-of-band-gap-in-mose2-grown-by-molecular-beam-epitaxy
#4
Byoung Ki Choi, Minu Kim, Kwang-Hwan Jung, Jwasoon Kim, Kyu-Sang Yu, Young Jun Chang
We report on a temperature-dependent band gap property of epitaxial MoSe2 ultrathin films. We prepare uniform MoSe2 films epitaxially grown on graphenized SiC substrates with controlled thicknesses by molecular beam epitaxy. Spectroscopic ellipsometry measurements upon heating sample in ultra-high vacuum showed temperature-dependent optical spectra between room temperature to 850 °C. We observed a gradual energy shift of optical band gap depending on the measurement temperature for different film thicknesses...
August 15, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28812071/towards-completing-the-cyclopropenylidene-cycle-rovibrational-analysis-of-cyclic-n3-cnn-hcnn-and-cnc
#5
Ryan C Fortenberry, Timothy J Lee, Xinchuan Huang
The simple aromatic hydrocarbon, cyclopropenylidene (c-C3H2), is a known, naturally-occurring molecule. The question remains as to whether its isoelectronic, cyclic, fellow aromatics of c-N3(+), c-CNN, HCNN(+), and c-CNC(-) are as well. Each of these are exciting objects for observation of Titan, and the rotational constants and vibrational frequencies produced here will allow for remote sensing of Titan's atmosphere or other astrophysical or terrestrial sources. None of these four aromatic species are vibrationally strong absorbers/emitters, but the two ions, HCNN(+) and c-CNC(-), have dipole moments of greater than 3 D and 1 D, respectively, making them good targets for rotational spectroscopic observation...
August 16, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28811801/pakistan-journal-of-medical-sciences-a-bibliometric-assessment-2001-2010
#6
Zameer Hussain Baladi, Loung V Umedani
OBJECTIVE: The aim of this study was to measure the growth of scientific research, authors' productivity, affiliation with the institute and geographic locations published in the Pakistan Journal of Medical Sciences during the period of 2001 - 2010. METHODS: This numerical analysis was conducted during mid-August 2016 to mid-October, 2016. The data for the study was downloaded from websites of e-journal of Pakistan Journal of Medical Sciences (PJMS) and Pak Medi-Net Com...
May 2017: Pakistan Journal of Medical Sciences Quarterly
https://www.readbyqxmd.com/read/28811466/time-lapse-crystallography-snapshots-of-a-double-strand-break-repair-polymerase-in-action
#7
Joonas A Jamsen, William A Beard, Lars C Pedersen, David D Shock, Andrea F Moon, Juno M Krahn, Katarzyna Bebenek, Thomas A Kunkel, Samuel H Wilson
DNA polymerase (pol) μ is a DNA-dependent polymerase that incorporates nucleotides during gap-filling synthesis in the non-homologous end-joining pathway of double-strand break repair. Here we report time-lapse X-ray crystallography snapshots of catalytic events during gap-filling DNA synthesis by pol μ. Unique catalytic intermediates and active site conformational changes that underlie catalysis are uncovered, and a transient third (product) metal ion is observed in the product state. The product manganese coordinates phosphate oxygens of the inserted nucleotide and PPi...
August 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28811238/i-index-is-not-an-accurate-indicator-of-icteria-in-conjugated-hyperbilirubinemia
#8
Nora Nikolac Gabaj, Marijana Miler, Roman Mihic
INTRODUCTION: Serum indices have become a standard in assessing degree of endogenous interferences in serum and plasma samples. The aim of this study was to evaluate accuracy of I index in comparison with total bilirubin concentration in icteric samples with ranging amount of conjugated bilirubin. MATERIALS AND METHODS: This study retrospectively analyzed data from laboratory information system. Total, conjugated bilirubin and I index are measured on Abbott Architect c8000 (N=900)...
August 12, 2017: Clinica Chimica Acta; International Journal of Clinical Chemistry
https://www.readbyqxmd.com/read/28810178/distance-dependent-fluorescence-quenching-and-enhancement-of-gold-nanoclusters-by-gold-nanoparticles
#9
Haiyan Qin, Diao Ma, Jianxiu Du
The interaction between fluorescent gold nanoclusters (AuNCs) and gold nanoparticles (AuNPs) has been investigated. It was observed that the fluorescence of AuNCs was remarkably quenched when direct contact with AuNPs. The fluorescence quenching of AuNCs by AuNPs was dynamic quenching and exhibited size-dependent property. A larger size of AuNPs displayed a stronger quenching effect and gave a larger quenching constant. When a silica spacer shell was introduced between AuNPs and AuNCs, a fluorescence enhancement of AuNCs by Au@SiO2 NPs was observed...
August 10, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28809755/multiple-timescales-in-the-photoswitching-kinetics-of-crystalline-thin-films-of-azobenzene-trimers
#10
Christopher Weber, Linus Pithan, Anton Zykov, Sebastian Bommel, Francesco Carla, Roberto Felici, Christopher Knie, David Bléger, Stefan Kowarik
Functional materials that exhibit photoinduced structural phase transitions are highly interesting for applications in optomechanics and mechanochemistry. It is, however, still not fully understood how photochemical reactions, which are often accompanied by molecular motion, proceed in confined and crystalline environments. Here we show that thin films of azobenzene trimers exhibit high structural order and determine the crystallographic unit cell. We demonstrate that the thin film can be switched partially reversibly between a crystalline and an amorphous phase...
August 15, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28809500/mechanisms-and-rates-of-u-vi-reduction-by-fe-ii-in-homogeneous-aqueous-solution-and-the-role-of-u-v-disproportionation
#11
Richard N Collins, Kevin M Rosso
Molecular-level pathways in the aqueous redox transformation of uranium by iron remain unclear, despite the importance of this knowledge for predicting uranium transport and distribution in natural and engineered environments. As the relative importance of homogeneous versus heterogeneous pathways is difficult to probe experimentally, here we apply computational molecular simulation to isolate rates of key one electron transfer reactions in the homogenous pathway. By comparison to experimental observations the role of the heterogeneous pathway also becomes clear...
August 15, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28808984/multiple-gas-phase-conformations-of-a-synthetic-linear-poly-acrylamide-polymer-observed-using-ion-mobility-mass-spectrometry
#12
Jean R N Haler, Johann Far, Abdelhafid Aqil, Jan Claereboudt, Nick Tomczyk, Kevin Giles, Christine Jérôme, Edwin De Pauw
Ion mobility-mass spectrometry (IM-MS) has emerged as a powerful separation and identification tool to characterize synthetic polymer mixtures and topologies (linear, cyclic, star-shaped,…). Electrospray coupled to IM-MS already revealed the coexistence of several charge state-dependent conformations for a single charge state of biomolecules with strong intramolecular interactions, even when limited resolving power IM-MS instruments were used. For synthetic polymers, the sample's polydispersity allows the observation of several chain lengths...
August 14, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28807999/role-of-co-occurring-competition-and-facilitation-in-plant-spacing-hydrodynamics-in-water-limited-environments
#13
Andrew C Trautz, Tissa H Illangasekare, Ignacio Rodriguez-Iturbe
Plant performance (i.e., fecundity, growth, survival) depends on an individual's access to space and resources. At the community level, plant performance is reflected in observable vegetation patterning (i.e., spacing distance, density) often controlled by limiting resources. Resource availability is, in turn, strongly dependent on plant patterning mediated by competitive and facilitative plant-plant interactions. Co-occurring competition and facilitation has never been specifically investigated from a hydrodynamic perspective...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28807922/are-standard-doses-of-piperacillin-in-piperacillin-tazobactam-regimens-adequate-for-the-management-of-febrile-neutropenia-answers-from-population-pharmacokinetic-modelling-and-monte-carlo-simulations
#14
Fekade Bruck Sime, Uwe Hahn, Morgyn S Warner, Ing Soo Tiong, Michael S Roberts, Jeffrey Lipman, Sandra L Peake, Jason A Roberts
Changes in the pharmacokinetics of piperacillin in febrile neutropenic patients have been reported to result in sub-optimal exposures. This study aimed to develop a population pharmacokinetic model for piperacillin and perform dosing simulation to describe optimal dosing regimens for haematological malignancy patients with febrile neutropenia. Concentration-time data were obtained from previous prospective observational pharmacokinetic and interventional therapeutic drug monitoring studies. Non-parametric population pharmacokinetic analysis and Monte Carlo dosing simulations were performed with Pmetrics® package for R...
August 14, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28807299/seasonality-and-circadian-variation-of-microfilaremia-in-dogs-experimentally-infected-with-dirofilaria-immitis
#15
Léonore Lovis, Mélanie Grandjean, Laurence Overney, Wolfgang Seewald, Heinz Sager
Periodicity, the cyclical rise and fall in microfilaria (mff) numbers in the peripheral blood over time, is observed in many filarial infections. It is correlated with the necessity for these larval stages to be ingested by the blood feeding vector before they can be transmitted to a new vertebrate host. Microfilariae of the dog heartworm Dirofilaria immitis have been described to show periodicity, but the circadian pattern does not seem to be consistent. Most publications describe the lowest mff-concentrations in the peripheral blood in the early morning, while the highest counts occurred either in the afternoon, in the late evening or shortly after midnight...
August 30, 2017: Veterinary Parasitology
https://www.readbyqxmd.com/read/28807068/secular-trends-in-dietary-patterns-of-young-children-in-brazil-from-1996-to-2006
#16
Ana Elisa Madalena Rinaldi, Wolney Lisboa Conde
OBJECTIVE: To describe dietary patterns (DP) from 1996 to 2006 and in the first 5 years of life and to explore individual and contextual characteristics associated with each DP. DESIGN: DP were defined by principal component analysis. The association between DP and individual (sociodemographic, maternal and child) and contextual (geographic regional and year) characteristics was analysed by multilevel analysis. SETTING: Two complex probabilistic Brazilian Demographic and Health Surveys (BDHS 1996, 2006)...
August 15, 2017: Public Health Nutrition
https://www.readbyqxmd.com/read/28806698/fluorescence-and-electron-paramagnetic-resonance-studies-of-norfloxacin-and-n-donor-mixed-ligand-ternary-copper-ii-complexes-stability-and-interaction-with-sds-micelles
#17
Gabriel S Vignoli Muniz, Jimmy Llontop Incio, Odivaldo C Alves, Klaus Krambrock, Letícia R Teixeira, Sonia R W Louro
The stability of ternary copper(II) complexes of a heterocyclic ligand, L (L being 2,2'-bipyridine (bipy) or 1,10-phenanthroline (phen)) and the fluorescent antibacterial agent norfloxacin (NFX) as the second ligand was studied at pH7.4 and different ionic strengths. Fluorescence quenching upon titration of NFX with the binary complexes allowed to obtain stability constants for NFX binding, Kb, as a function of ionic strength. The Kb values vary by more than two orders of magnitude when buffer concentration varies from 0...
August 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28806685/ecofriendly-gold-nanoparticles-lysozyme-interaction-thermodynamical-perspectives
#18
Swarup Roy, Shailendra K Saxena, Suryakant Mishra, Priyanka Yogi, P R Sagdeo, Rajesh Kumar
In the featured work interaction between biosynthesized gold nanoparticles (GNP) and lysozyme (Lys) has been studied using multi-spectroscopic approach. A moderate association constant (Kapp) of 2.66×10(4)L/mol has been observed indicative of interactive nature. The binding constant (Kb) was 1.99, 6.30 and 31.6×10(4)L/mol at 291, 298 and 305K respectively and the number of binding sites (n) was found to be approximately one. Estimated values of thermodynamic parameters (Enthalpy change, ΔH=141.99kJ/mol, entropy change, ΔS=570J/mol/K, Gibbs free energy change, ΔG=-27...
August 8, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28806487/gut-microbiome-response-to-short-term-dietary-interventions-in-reactive-hypoglycemia-subjects
#19
Sara Quercia, Silvia Turroni, Jessica Fiori, Matteo Soverini, Simone Rampelli, Elena Biagi, Andrea Castagnetti, Clarissa Consolandi, Marco Severgnini, Mario Pianesi, Francesco Fallucca, Paolo Pozzilli, Patrizia Brigidi, Marco Candela
BACKGROUND: Reactive hypoglycemia (RH) is a metabolic disorder that provokes severe hypoglycemic episodes after meal. Over recent years, the gut microbiota (GM) has been recognized as potential target for the control of metabolic diseases, and the possibility to correct GM dysbioses through diet, favoring the recovery of metabolic homeostasis, has been considered. METHODS: We investigate the impact of two short-term (3-day) nutritional interventions, based on the macrobiotic Ma-Pi 2 diet and a control Mediterranean diet, on the structure and functionality of the GM in 12 patients affected by RH...
August 14, 2017: Diabetes/metabolism Research and Reviews
https://www.readbyqxmd.com/read/28806453/neurologic-complications-associated-with-the-zika-virus-in-brazilian-adults
#20
Ivan Rocha Ferreira da Silva, Jennifer A Frontera, Ana Maria Bispo de Filippis, Osvaldo Jose Moreira do Nascimento
Importance: There are no prospective cohort studies assessing the incidence and spectrum of neurologic manifestations secondary to Zika virus (ZIKV) infection in adults. Objective: To evaluate the rates of acute ZIKV infection among patients hospitalized with Guillain-Barré syndrome (GBS), meningoencephalitis, or transverse myelitis. Design, Setting, and Participants: A prospective, observational cohort study was conducted at a tertiary referral center for neurological diseases in Rio de Janeiro, Brazil, between December 5, 2015, and May 10, 2016, among consecutive hospitalized adults (>18 years of age) with new-onset acute parainfectious or neuroinflammatory disease...
August 14, 2017: JAMA Neurology
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