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https://www.readbyqxmd.com/read/28732077/mutations-in-the-caenorhabditis-elegans-orthologs-of-human-genes-required-for-mitochondrial-trna-modification-cause-similar-electron-transport-chain-defects-but-different-nuclear-responses
#1
Carmen Navarro-González, Ismaïl Moukadiri, Magda Villarroya, Ernesto López-Pascual, Simon Tuck, M-Eugenia Armengod
Several oxidative phosphorylation (OXPHOS) diseases are caused by defects in the post-transcriptional modification of mitochondrial tRNAs (mt-tRNAs). Mutations in MTO1 or GTPBP3 impair the modification of the wobble uridine at position 5 of the pyrimidine ring and cause heart failure. Mutations in TRMU affect modification at position 2 and cause liver disease. Presently, the molecular basis of the diseases and why mutations in the different genes lead to such different clinical symptoms is poorly understood...
July 21, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28732042/numerical-study-on-the-lubrication-performance-of-compression-ring-cylinder-liner-system-with-spherical-dimples
#2
Cheng Liu, Yan-Jun Lu, Yong-Fang Zhang, Sha Li, Norbert Müller
The effects of surface texture on the lubrication performance of a compression ring-cylinder liner system are studied in this paper. By considering the surface roughness of the compression ring and cylinder liner, a mixed lubrication model is presented to investigate the tribological behaviors of a barrel-shaped compression ring-cylinder liner system with spherical dimples on the liner. In order to determine the rupture and reformulation positions of fluid film accurately, the Jacoboson-Floberg-Olsson (JFO) cavitation boundary condition is applied to the mixed lubrication model for ensuring the mass-conservative law...
2017: PloS One
https://www.readbyqxmd.com/read/28732003/-diffuse-type-of-gastric-cancer-adenocarcinoma-in-10-years-old-boy-report-of-a-case
#3
Nery Romero, Ingrid Zegarra, Hugo Delgado
We report a rare case of diffuse type of gastric cancer with signet ring cells in 10 years old boy who was admitted with a 12 months history with weight loss, dysphagia to solids first and to liquids later, anorexia, fatigue, dizziness, vomiting and later, with pain in the left upper quadrant. On examination, he appeared pale, malnourished, with café-au- lait spots over the trunk and extremities. Laboratory tests showed; Hb 7.5 g, albumin 2.62 g, Thevenon positive on stools. Abdominal ultrasound examination showed periaortic masses and diffuse space occupying lesions in the liver...
April 2017: Revista de Gastroenterología del Perú: órgano Oficial de la Sociedad de Gastroenterología del Perú
https://www.readbyqxmd.com/read/28731936/case-series-keratolimbal-allograft-as-a-patch-graft-for-glaucoma-drainage-devices
#4
Sarah F Ahmed, Mason Schmutz, Sameh Mosaed
PURPOSE: Tube exposure remains one of the most common complications after glaucoma drainage device (GDD) implantation, despite various types of patch grafts available today. We present a 4 patient case series following the effectivity of the keratolimbal allograft (KLAL) as a patch graft for cases of tube exposure. Given its inherent population of stem cells, our hypothesis was that this highly replicative, biological tissue would provide an adequate means of glaucoma tube coverage. The subset of patients chosen for the KLAL patch graft all had a history of abnormally scarred conjunctiva or thin sclera...
July 20, 2017: Journal of Glaucoma
https://www.readbyqxmd.com/read/28731922/a-novel-g-55040074delt-in-alas2-gene-resulting-in-a-monomeric-protein-and-severe-sideroblastic-anemia-phenotype
#5
Prateek Bhatia, Aditya Singh, Avani Hedge
Sideroblastic anemias are a rare group of disorders resulting from defective iron incorporation during heme synthesis and hence characterized by anemia and presence of ringed sideroblasts in bone marrow. The most common form is an X-linked disorder caused by mutations in ALAS2 gene. In the current paper, a case of X-linked sideroblastic anemia caused by a novel homozygous deletional mutation in exon 10 of ALAS2 gene is presented. The female infant developed moderately severe anemia at 6 months of age, which did not improve despite adequate nutritional support...
July 20, 2017: Journal of Pediatric Hematology/oncology
https://www.readbyqxmd.com/read/28731769/first-principles-prediction-of-spin-polarized-multiple-dirac-rings-in-manganese-fluoride
#6
Yalong Jiao, Fengxian Ma, Chunmei Zhang, John Bell, Stefano Sanvito, Aijun Du
Spin-polarized materials with Dirac features have sparked great scientific interest due to their potential applications in spintronics. But such a type of structure is very rare and none has been fabricated. Here, we investigate the already experimentally synthesized manganese fluoride (MnF_{3}) as a novel spin-polarized Dirac material by using first-principles calculations. MnF_{3} exhibits multiple Dirac cones in one spin orientation, while it behaves like a large gap semiconductor in the other spin channel...
July 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28731766/observing-dissipative-topological-defects-with-coupled-lasers
#7
Vishwa Pal, Chene Tradonsky, Ronen Chriki, Asher A Friesem, Nir Davidson
Topological defects have been observed and studied in a wide range of systems, such as cosmology, spin systems, cold atoms, and optics, as they are quenched across a phase transition into an ordered state. These defects limit the coherence of the system and its ability to approach a fully ordered state, so revealing their origin and control is becoming an increasingly important field of research. We observe dissipative topological defects in a one-dimensional ring of phased-locked lasers, and show how their formation is related to the Kibble-Zurek mechanism and is governed in a universal manner by two competing time scales...
July 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28731757/phase-locking-the-spin-precession-in-a-storage-ring
#8
N Hempelmann, V Hejny, J Pretz, E Stephenson, W Augustyniak, Z Bagdasarian, M Bai, L Barion, M Berz, S Chekmenev, G Ciullo, S Dymov, F-J Etzkorn, D Eversmann, M Gaisser, R Gebel, K Grigoryev, D Grzonka, G Guidoboni, T Hanraths, D Heberling, J Hetzel, F Hinder, A Kacharava, V Kamerdzhiev, I Keshelashvili, I Koop, A Kulikov, A Lehrach, P Lenisa, N Lomidze, B Lorentz, P Maanen, G Macharashvili, A Magiera, D Mchedlishvili, S Mey, F Müller, A Nass, N N Nikolaev, A Pesce, D Prasuhn, F Rathmann, M Rosenthal, A Saleev, V Schmidt, Y Semertzidis, V Shmakova, A Silenko, J Slim, H Soltner, A Stahl, R Stassen, H Stockhorst, H Ströher, M Tabidze, G Tagliente, R Talman, P Thörngren Engblom, F Trinkel, Yu Uzikov, Yu Valdau, E Valetov, A Vassiliev, C Weidemann, A Wrońska, P Wüstner, P Zuprański, M Żurek
This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97  GeV/c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (≈121  kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization...
July 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28731716/the-inheritance-angle-a-determinant-for-the-number-of-members-in-the-substituted-cucurbit-n-uril-family
#9
Yi Zhao, Vijaybabu Mandadapu, Hasti Iranmanesh, Jonathon E Beves, Anthony I Day
Two new glycoluril diethers have been prepared, bearing strained cyclobutene and cyclobutane rings at the fused junction of the two imidazolidinone rings. The wide angle of the concave face of the cyclobutano derivative enabled the synthesis of cyclobutanocucurbit[5-8]uril, the largest member being the most significant achievement. A limited binding affinity study compared the new substituted family to classical cucurbit[5-8]uril. Surprisingly lower affinities were found, except for cyclobutanocucurbit[6]uril, which was 3...
July 21, 2017: Organic Letters
https://www.readbyqxmd.com/read/28731705/reversible-self-assembly-of-degradable-polymersomes-with-upper-critical-solution-temperature-in-water
#10
Thomas Wolf, Timo Rheinberger, Johanna Simon, Frederik R Wurm
Temperature-induced self-assembly of block copolymers allows the formation of smart nanodimensional structures. Mostly, non-degradable LCST segments are applied to prepare such dynamic aggregates. However, degradable UCST block copolymers that would allow the swelling or disassembly at elevated temperatures with eventual backbone hydrolysis have not been reported to date. We present the first well-defined degradable poly(phosphonate)s with adjustable UCST. The organocatalytic anionic ring-opening copolymerization of 2-alkyl-2-oxo-1,3,2-dioxaphospholanes provided functional polymers with excellent control over molecular weight and copolymer composition...
July 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28731690/the-metal-drives-the-chemistry-dual-functions-of-acireductone-dioxygenase
#11
Aditi R Deshpande, Thomas C Pochapsky, Dagmar Ringe
Acireductone dioxygenase (ARD) from the methionine salvage pathway (MSP) is a unique enzyme that exhibits dual chemistry determined solely by the identity of the divalent transition-metal ion (Fe(2+) or Ni(2+)) in the active site. The Fe(2+)-containing isozyme catalyzes the on-pathway reaction using substrates 1,2-dihydroxy-3-keto-5-methylthiopent-1-ene (acireductone) and dioxygen to generate formate and the ketoacid precursor of methionine, 2-keto-4-methylthiobutyrate, whereas the Ni(2+)-containing isozyme catalyzes an off-pathway shunt with the same substrates, generating methylthiopropionate, carbon monoxide, and formate...
July 21, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28731688/the-%C3%AF-configuration-of-the-www-motif-of-a-short-trp-rich-peptide-is-critical-for-targeting-bacterial-membranes-disrupting-preformed-biofilms-and-killing-methicillin-resistant-staphylococcus-aureus
#12
D Zarena, Biswajit Mishra, Tamara Lushnikova, Fangyu Wang, Guangshun Wang
Tryptophan-rich peptides, being short and suitable for large-scale chemical synthesis, are attractive candidates for developing a new generation of antimicrobials to combat antibiotic-resistant bacteria (superbugs). Although there are numerous pictures for membrane-bound structure of a single tryptophan (W), how multiple Trp amino acids assemble themselves and interact with bacterial membranes are poorly understood. This communication presents the three-dimensional structure for an eight-residue Trp-rich peptide (WWWLRKIW-NH2 with 50% W) determined by the improved 2D NMR method, which includes the measurements of 13C and 15N chemical shifts at natural abundance...
July 21, 2017: Biochemistry
https://www.readbyqxmd.com/read/28731587/reversible-pressure-controlled-depolymerization-of-a-copper-ii-containing-coordination-polymer
#13
Jack Kay Clegg, Aidan Brock, Katrina Jolliffe, Simon Parsons, Leonard Lindoy, Peter Tasker, Fraser White
A unique pressure-induced Cu-N bond breaking/bond forming reaction is reported. The variation of pressure on a single crystal of a one-dimensional copper(II)-containing coordination polymer (Cu2L2(1-methylpiperazine)2]n, where H2L is 1,1'-(1,3-phenylene)-bis(4,4-dimethylpentane-1,3-dione)), was monitored using single crystal X-ray diffraction with the aid of a diamond anvil cell. At a very low elevated pressure (~0.05 GPa) a remarkable reversible phase change was observed. The phase change results in the depolymerization of the material through the cleavage and formation of axial Cu-N bonds as well as "ring flips" of individual axially coordinated 1-methylpiperazine ligands...
July 21, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28731346/kinetics-of-light-induced-intramolecular-energy-transfer-in-different-conformational-states-of-nadh
#14
Zsuzsanna Heiner, Thomas Roland, Jérémie Léonard, Stefan Haacke, Géza I Groma
When bound to a protein, the coenzyme NAD+/NADH typically exists in an extended conformation, while in aqueous solutions it can be characterized by an equilibrium of folded and unfolded structures. It was recognized long ago that in the folded conformation light absorption at the adenine ring initiates an effective energy transfer (ET) towards the nicotinamide group, but the mechanism of this process is still unexplored. Here we apply ultrafast transient absorption measurements on NADH combined with compartmental model analysis for following the kinetics of the ET...
July 21, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28731301/lead-ii-complexes-of-amino-acids-peptides-and-other-related-ligands-of-biological-interest
#15
Etelka Farkas, Péter Buglyó
Lead(II) forms (NH2,COO-)-chelated mono- and bis-complexes with simple amino acids, while mono-complexes with pH-dependent coordination modes exist with simple dipeptides. These mostly hemidirected complexes have moderate stability. While a weak interaction of side chain imidazole and carboxylate in lead(II)-aminoacidato complexes is found, the thiolate group has an exceptionally high affinity to this metal ion. For example, tridentate (NH2,COO-,S-)-coordination of penicillamine (Pen) and cysteine (Cys) results in an extremely strong interaction with lead(II), but, owing to the sterical effect of the 6s2 pair, a second ligand is not able to coordinate in the above mentioned tridentate way...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28731227/dithiopheneindenofluorene-tif-semiconducting-polymers-with-very-high-mobility-in-field-effect-transistors
#16
Hu Chen, Michael Hurhangee, Mark Nikolka, Weimin Zhang, Mindaugas Kirkus, Marios Neophytou, Samuel J Cryer, David Harkin, Pascal Hayoz, Mojtaba Abdi-Jalebi, Christopher R McNeill, Henning Sirringhaus, Iain McCulloch
The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone...
July 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28731123/lasiodiplactone-a-a-novel-lactone-from-the-mangrove-endophytic-fungus-lasiodiplodia-theobromae-zj-hq1
#17
Senhua Chen, Zhaoming Liu, Hongju Liu, Yuhua Long, Dongni Chen, Yongjun Lu, Zhigang She
Lasiodiplactone A (1), an unprecedented lactone, was obtained from the mangrove endophytic fungus Lasiodiplodia theobromae ZJ-HQ1. The structure of 1 was established by analysis of NMR spectroscopic data and electronic circular dichroism (ECD) spectra. Lasiodiplactone A (1) was the first example of lactone that possesses a unique tetracyclic system (12/6/6/5) of RAL12 (12-membered β-resorcylic acid lactone) with a pyran ring and a furan ring. A possible biogenetic pathway for 1 was proposed. Compound 1 showed anti-inflammatory activity by inhibiting nitric oxide (NO) production in lipopolysaccharide activated in RAW264...
July 21, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28731099/novel-phosphorescent-cationic-iridium-iii-complexes-with-o-carboranylation-on-the-ancillary-n-n-ligand
#18
Xiang Li, Yongheng Yin, Hong Yan, Changsheng Lu, Qiang Zhao
A novel series of heteroleptic iridium complexes with 2-phenyl-pyridine as a main ligand and carborane-functionalized 2,2'-bipyridine as an ancillary ligand were synthesized, and characterized as [Ir(ppy)2(By)]PF6 (where ppy is 2-phenyl-pyridine, By is 5-(2-R-Cb)-2,2'-bipyridine, R = H (2a), CH3 (2b), Ph (2c), iPr (2d) and iBu (2e), or By is 4-(2-R-Cb)-2,2'-bipyridine while R = H (3a), CH3 (3b), Ph (3c), iPr (3d) and iBu (3e), Cb = o-carboran-1-yl). The R groups and the substitution sites of carborane on the pyridine ring have caused differences in the emission properties of these complexes...
July 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28730961/novel-fluorinated-porphyrins-sensitize-tumor-cells-to-photodamage-in-normoxia-and-hypoxia-synthesis-and-biocompatible-formulations
#19
Elizaveta V Belyaeva, Alina A Markova, Dmitry N Kaluzhnyb, Andrei L Sigan, Lev L Gervitz, Aida N Ataeva, Nikolai D Chkanikov, Alexander A Shtil
: Background. Hypoxia renders tumor cells refractory to treatment. One way to overcome this problem is the design of drug delivery systems that contain the antitumor agent within an oxygen supply medium. OBJECTIVE: to evaluate whether the perfluorocarbon liquids (capable of retaining up to 50% v/v amounts of O2 gas) can be tools for delivery of photosensitizers to hypoxic tumors. METHOD: We synthesized a series of compounds in which fluoroaliphatic or fluoroaromatic moieties were conjugated to the porphyrin ring in meso-positions...
July 19, 2017: Anti-cancer Agents in Medicinal Chemistry
https://www.readbyqxmd.com/read/28730819/hypervalent-iodine-reagent-mediated-oxidative-heterocyclization-of-aldoximes-with-heterocyclic-alkenes
#20
Akira Yoshimura, Khiem C Nguyen, Gregory T Rohde, Pavel S Postnikov, Mekhman S Yusubov, Viktor V Zhdankin
An efficient cycloaddition of heterocyclic alkenes with nitrile oxides generated in situ from the corresponding aldoximes using organohypervalent iodine(III) reagent, [hydroxy(tosyloxy)iodo]benzene (Koser's reagent), has been developed. The oxidative cyclization of various aldoximes with 1-propene-1,3-sultone affords the respective isoxazoline-ring fused heterobicyclic products in moderate to good yields. Furthermore, the reaction of aldoxime with a cyclic phospholene-oxide under similar conditions produces the corresponding heterobicyclic phospholene oxides in moderate yields...
July 21, 2017: Journal of Organic Chemistry
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