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https://www.readbyqxmd.com/read/28102965/isotope-probing-of-the-udp-apiose-udp-xylose-synthase-reaction-evidence-of-a-mechanism-via-a-coupled-oxidation-and-aldol-cleavage
#1
Thomas Eixelsberger, Doroteja Horvat, Alexander Gutmann, Hansjörg Weber, Bernd Nidetzky
The C-branched sugar d-apiose (Api) is essential for plant cell-wall development. An enzyme-catalyzed decarboxylation/pyranoside ring-contraction reaction leads from UDP-α-d-glucuronic acid (UDP-GlcA) to the Api precursor UDP-α-d-apiose (UDP-Api). We examined the mechanism of UDP-Api/UDP-α-d-xylose synthase (UAXS) with site-selectively (2) H-labeled and deoxygenated substrates. The analogue UDP-2-deoxy-GlcA, which prevents C-2/C-3 aldol cleavage as the plausible initiating step of pyranoside-to-furanoside conversion, did not give the corresponding Api product...
January 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28102930/modulation-of-the-thermodynamic-signatures-of-an-rna-thermometer-by-osmolytes-and-salts
#2
Mimi Gao, Loana Arns, Roland Winter
Folding of ribonucleic acids (RNAs) is driven by several factors, such as base pairing and stacking, chain entropy, and ion-mediated electrostatics, which have been studied in great detail. However, the power of background molecules in the cellular milieu is often neglected. Herein, we study the effect of common osmolytes on the folding equilibrium of a hairpin-structured RNA and, using pressure perturbation, provide novel thermodynamic and volumetric insights into the modulation mechanism. The presence of TMAO causes an increased thermal stability and a more positive volume change for the helix-to-coil transition, whereas urea destabilizes the hairpin and leads to an increased expansibility of the unfolded state...
January 19, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28102818/is-cell-size-a-spandrel
#3
Ariel Amir
All organisms control the size of their cells. We focus here on the question of size regulation in bacteria, and suggest that the quantitative laws governing cell size and its dependence on growth rate may arise as byproducts of a regulatory mechanism which evolved to support multiple DNA replication forks. In particular, we show that the increase of bacterial cell size during Lenski's long-term evolution experiments is a natural outcome of this proposal. This suggests that, in the context of evolution, cell size may be a 'spandrel'...
January 19, 2017: ELife
https://www.readbyqxmd.com/read/28102757/dysbiosis-in-crohn-s-disease-joint-action-of-stochastic-injuries-and-focal-inflammation-in-the-gut
#4
Ludovica F Buttó, Dirk Haller
Gut homeostasis involves interrelated biological networks that include the immune system, specialized cells of the epithelium, such as Paneth and goblet cells, as well as triggers derived from the microbiota. Disruption of these homeostatic interactions may lead to the pathogenesis of inflammatory bowel diseases (IBD). To develop more targeted and individual treatments in Crohn's disease and ulcerative colitis, it becomes more and more important to link key mechanisms of the disease pathogenesis to distinct IBD subsets...
January 19, 2017: Gut Microbes
https://www.readbyqxmd.com/read/28102588/three-dimensional-translabial-ultrasound-assessment-of-urethral-supports-and-the-urethral-sphincter-complex-in-stress-urinary-incontinence
#5
Jordi Cassadó Garriga, Antoni Pessarrodona Isern, Monica Rodríguez Carballeira, Mar Pallarols Badia, Manuela Moya Del Corral, Marta Valls Esteve, Eva Huguet Galofré
AIMS: The pathophysiological mechanism of incontinence is multifactorial. We evaluated the role of 3D-4D ultrasound in the assessment of the fascial supports of the urethra and the urethral sphincter complex (USC) for diagnosing stress urinary incontinence. METHODS: Observational case-control study in women with and without stress urinary incontinence attending a urogynecology service and a general gynecology service. All women were interviewed, examined, and classified according to the Pelvic Organ Prolapse Quantification (POP-Q) and underwent a 3D-4D translabial ultrasound...
January 19, 2017: Neurourology and Urodynamics
https://www.readbyqxmd.com/read/28102558/concise-reviews-regeneration-in-mammalian-cochlea-hair-cells-help-from-supporting-cells-transdifferentiation
#6
Bénédicte Franco, Brigitte Malgrange
It is commonly assumed that mammalian cochlear cells do not regenerate. Therefore, if hair cells are lost following an injury, no recovery could occur. However, during the first postnatal week, mice harbor some progenitor cells that retain the ability to give rise to new hair cells. These progenitor cells are in fact supporting cells. Upon hair cells loss, those cells are able to generate new hair cells both by direct transdifferentiation or following cell cycle re-entry and differentiation. However, this property of supporting cells is progressively lost after birth...
January 19, 2017: Stem Cells
https://www.readbyqxmd.com/read/28102546/ataluren-and-similar-compounds-specific-therapies-for-premature-termination-codon-class-i-mutations-for-cystic-fibrosis
#7
REVIEW
Aisha A Aslam, Colin Higgins, Ian P Sinha, Kevin W Southern
BACKGROUND: Cystic fibrosis is a common life-shortening genetic disorder in the Caucasian population (less common in other ethnic groups) caused by the mutation of a single gene that codes for the production of the cystic fibrosis transmembrane conductance regulator protein. This protein coordinates the transport of salt (and bicarbonate) across cell surfaces and the mutation most notably affects the airways. In the lungs of people with cystic fibrosis, defective protein results in a dehydrated surface liquid and compromised mucociliary clearance...
January 19, 2017: Cochrane Database of Systematic Reviews
https://www.readbyqxmd.com/read/28102515/attention-deficit-hyperactivity-disorder-adhd-and-obesity-update-2016
#8
REVIEW
Samuele Cortese, Luca Tessari
While psychiatric comorbidities of attention-deficit/hyperactivity disorder (ADHD) have been extensively explored, less attention has been paid to somatic conditions possibly associated with this disorder. However, mounting evidence in the last decade pointed to a possible significant association between ADHD and certain somatic conditions, including obesity. This papers provides an update of a previous systematic review on the relationship between obesity and ADHD (Cortese and Vincenzi, Curr Top Behav Neurosci 9:199-218, 2012), focusing on pertinent peer-reviewed empirical papers published since 2012...
January 2017: Current Psychiatry Reports
https://www.readbyqxmd.com/read/28102389/the-decomposition-of-benzenesulfonyl-azide-a-matrix-isolation-and-computational-study
#9
Guohai Deng, Xuelin Dong, Qifan Liu, Dingqing Li, Hongmin Li, Qiao Sun, Xiaoqing Zeng
The thermal-decomposition and photo-decomposition of benzenesulfonyl azide, PhS(O)2N3, have been studied by combining matrix-isolation IR spectroscopy and quantum chemical calculations. Upon flash vacuum pyrolysis at 800 K, the azide splits off molecular nitrogen and exclusively furnishes phenylnitrene (PhN) and SO2 in the gas phase. In contrast, the azide favors stepwise photodecomposition in solid Ar and Ne matrices at 2.8 K. Specifically, the UV laser photolysis (193 and 266 nm) of PhS(O)2N3 results in the formation of the key nitrene intermediate PhS(O)2N in the triplet ground state, which undergoes pseudo-Curtius rearrangement into N-sulfonyl imine PhNSO2 under subsequent visible light irradiation (380-450 nm)...
January 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28102362/evaluation-of-region-selective-bilirubin-induced-brain-damage-as-a-basis-for-a-pharmacological-treatment
#10
Matteo Dal Ben, Cristina Bottin, Fabrizio Zanconati, Claudio Tiribelli, Silvia Gazzin
The neurologic manifestations of neonatal hyperbilirubinemia in the central nervous system (CNS) exhibit high variations in the severity and appearance of motor, auditory and cognitive symptoms, which is suggestive of a still unexplained selective topography of bilirubin-induced damage. By applying the organotypic brain culture (OBC: preserving in vitro the cellular complexity, connection and architecture of the in vivo brain) technique to study hyperbilirubinemia, we mapped the regional target of bilirubin-induced damage, demonstrated a multifactorial toxic action of bilirubin, and used this information to evaluate the efficacy of drugs applicable to newborns to protect the brain...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102332/dynamic-modeling-of-uteroplacental-blood-flow-in-iugr-indicates-vortices-and-elevated-pressure-in-the-intervillous-space-a-pilot-study
#11
Christian J Roth, Eva Haeussner, Tanja Ruebelmann, Franz V Koch, Christoph Schmitz, Hans-Georg Frank, Wolfgang A Wall
Ischemic placental disease is a concept that links intrauterine growth retardation (IUGR) and preeclampsia (PE) back to insufficient remodeling of uterine spiral arteries. The rheological consequences of insufficient remodeling of uterine spiral arteries were hypothesized to mediate the considerably later manifestation of obstetric disease. However, the micro-rheology in the intervillous space (IVS) cannot be examined clinically and rheological animal models of the human IVS do not exist. Thus, an in silico approach was implemented to provide in vivo inaccessible data...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102320/polarization-conversion-in-plasmonic-nanoantennas-for-metasurfaces-using-structural-asymmetry-and-mode-hybridization
#12
Peter R Wiecha, Leo-Jay Black, Yudong Wang, Vincent Paillard, Christian Girard, Otto L Muskens, Arnaud Arbouet
Polarization control using single plasmonic nanoantennas is of interest for subwavelength optical components in nano-optical circuits and metasurfaces. Here, we investigate the role of two mechanisms for polarization conversion by plasmonic antennas: Structural asymmetry and plasmon hybridization through strong coupling. As a model system we investigate L-shaped antennas consisting of two orthogonal nanorods which lengths and coupling strength can be independently controlled. An analytical model based on field susceptibilities is developed to extract key parameters and to address the influence of antenna morphology and excitation wavelength on polarization conversion efficiency and scattering intensities...
January 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28102317/time-resolved-neutron-scattering-provides-new-insight-into-protein-substrate-processing-by-a-aaa-unfoldase
#13
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/28102262/scaling-single-cell-genomics-from-phenomenology-to-mechanism
#14
Amos Tanay, Aviv Regev
Three of the most fundamental questions in biology are how individual cells differentiate to form tissues, how tissues function in a coordinated and flexible fashion and which gene regulatory mechanisms support these processes. Single-cell genomics is opening up new ways to tackle these questions by combining the comprehensive nature of genomics with the microscopic resolution that is required to describe complex multicellular systems. Initial single-cell genomic studies provided a remarkably rich phenomenology of heterogeneous cellular states, but transforming observational studies into models of dynamics and causal mechanisms in tissues poses fresh challenges and requires stronger integration of theoretical, computational and experimental frameworks...
January 18, 2017: Nature
https://www.readbyqxmd.com/read/28102109/epigenetic-regulation-of-rgs2-regulator-of-g-protein-signaling-2-in-chemoresistant-ovarian-cancer-cells
#15
Ercan Cacan
Regulator of G-protein signaling 2 (RGS2) is a GTPase-activating protein functioning as an inhibitor of G-protein coupled receptors (GPCRs). RGS2 dysregulation was implicated in solid tumour development and RGS2 downregulation has been reported in prostate and ovarian cancer progression. However, the molecular mechanism by which RGS2 expression is suppressed in ovarian cancer remains unknown. The expression and epigenetic regulation of RGS2 in chemosensitive and chemoresistant ovarian cancer cells were determined by qRT-PCR and chromatin immunoprecipitation assays, respectively...
January 19, 2017: Journal of Chemotherapy
https://www.readbyqxmd.com/read/28102015/circulating-antioxidant-levels-and-risk-of-prostate-cancer-by-tmprss2-erg
#16
Rebecca E Graff, Gregory Judson, Thomas U Ahearn, Michelangelo Fiorentino, Massimo Loda, Edward L Giovannucci, Lorelei A Mucci, Andreas Pettersson
BACKGROUND: Few studies have considered etiological differences across molecular subtypes of prostate cancer, despite potential to improve opportunities for precision prevention of a disease for which modifiable risk factors have remained elusive. Factors that lead to DNA double-strand breaks, such as oxidative stress, may promote the formation of the TMPRSS2:ERG gene fusion in prostate cancer. We tested the hypothesis that increasing levels of pre-diagnostic circulating antioxidants, which may reduce oxidative stress, are associated with lower risk of developing TMPRSS2:ERG positive prostate cancer...
January 19, 2017: Prostate
https://www.readbyqxmd.com/read/28101863/lessons-from-animal-models-of-cytoplasmic-intermediate-filament-proteins
#17
Jamal-Eddine Bouameur, Thomas M Magin
Cytoplasmic intermediate filaments (IFs) represent a major cytoskeletal network contributing to cell shape, adhesion and migration as well as to tissue resilience and renewal in numerous bilaterians, including mammals. The observation that IFs are dispensable in cultured mammalian cells, but cause tissue-specific, life-threatening disorders, has pushed the need to investigate their function in vivo. In keeping with human disease, the deletion or mutation of murine IF genes resulted in highly specific pathologies...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101860/the-structure-and-topology-of-%C3%AE-helical-coiled-coils
#18
Andrei N Lupas, Jens Bassler, Stanislaw Dunin-Horkawicz
α-Helical coiled coils constitute one of the most diverse folds yet described. They range in length over two orders of magnitude; they form rods, segmented ropes, barrels, funnels, sheets, spirals, and rings, which encompass anywhere from two to more than 20 helices in parallel or antiparallel orientation; they assume different helix crossing angles, degrees of supercoiling, and packing geometries. This structural diversity supports a wide range of biological functions, allowing them to form mechanically rigid structures, provide levers for molecular motors, project domains across large distances, mediate oligomerization, transduce conformational changes and facilitate the transport of other molecules...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28101849/mechanistic-study-of-the-gas-phase-in-source-hofmann-elimination-of-doubly-quaternized-cinchona-alkaloid-based-phase-transfer-catalysts-by-electrospray-ionization-tandem-mass-spectrometry
#19
Rong-Sheng Yang, Huaming Sheng, Katrina W Lexa, Edward C Sherer, Li-Kang Zhang, Bangping Xiang, Roy Helmy, Bing Mao
An unusual in-source fragmentation pattern observed for 14 doubly quaternized cinchona alkaloid-based phase-transfer catalysts (PTC) was studied using (+)-ESI high resolution mass spectrometry. Loss of the substituted benzyl cation (R1 or R2) was found to be the major product ion [M(2+) - R1(+) or R2(+)](+) in MS spectra of all PTC compounds. A Hofmann elimination product ion [M - H](+) was also observed. Only a small amount of the doubly charged M(2+) ions were observed in the MS spectra, likely due to strong Columbic repulsion between the two quaternary ammonium cations in the gas phase...
January 18, 2017: Journal of the American Society for Mass Spectrometry
https://www.readbyqxmd.com/read/28101847/off-target-anti-inflammatory-activity-of-the-p2x7-receptor-antagonist-az11645373
#20
Olga V Oskolkova, Viktoria Godschachner, Valery N Bochkov
We have found that a well-characterized P2X7 receptor antagonist AZ11645373 blocked production of pro-inflammatory chemokine IL-8 in endothelial cells treated with OxPAPC. The effect was not due to toxicity of AZ11645373 as documented by cellular metabolic activity assay. The mechanism of inhibition by AZ11645373 was apparently independent of the P2X7 receptor because this receptor was not involved in induction of IL-8 under our experimental conditions. In support of this notion, two P2X7 agonists ATP and BzATP did not upregulate IL-8...
January 19, 2017: Inflammation
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