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https://www.readbyqxmd.com/read/29783146/gas-chromatographic-mass-spectrometric-characterization-of-thebaol-an-opium-constituent-and-its-structural-analogs
#1
Levan Megutnishvili, Nino Todua, Stephen Stein, Anzor Mikaia
A GC-MS method is described for the characterization of thebaol, a component of opium poppy. The method includes preliminary sample derivatization to TMS, TBDMS, TFA, PFP and HFB substituted products. Fragmentation of resulting derivatives is unique under electron ionization, and proceeds via consecutive loss of two radicals that violate the "even-electron rule". Peaks of [M-2CH3 ]+. and [M-C4 H9 -CH3 ]+. ions show maximum intensities in the spectra of trimethyl- and tert-butyldimethylsilyl-thebaols...
May 18, 2018: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29779899/signaling-dependent-control-of-apical-membrane-size-and-self-renewal-in-rosette-stage-human-neuroepithelial-stem-cells
#2
Jan-Philip Medelnik, Kathleen Roensch, Satoshi Okawa, Antonio Del Sol, Osvaldo Chara, Levan Mchedlishvili, Elly M Tanaka
In the developing nervous system, neural stem cells are polarized and maintain an apical domain facing a central lumen. The presence of apical membrane is thought to have a profound influence on maintaining the stem cell state. With the onset of neurogenesis, cells lose their polarization, and the concomitant loss of the apical domain coincides with a loss of the stem cell identity. Little is known about the molecular signals controlling apical membrane size. Here, we use two neuroepithelial cell systems, one derived from regenerating axolotl spinal cord and the other from human embryonic stem cells, to identify a molecular signaling pathway initiated by lysophosphatidic acid that controls apical membrane size and consequently controls and maintains epithelial organization and lumen size in neuroepithelial rosettes...
May 10, 2018: Stem Cell Reports
https://www.readbyqxmd.com/read/29777538/-the-evolution-of-eyebrow-morphology-the-westmore-model-revisited
#3
Samer Jabbour, Marwan Nasr, Elio Kechichian, Sandrine S Aderian, Iad Nseir, Philippe Levan, Warren Noel
BACKGROUND: The most widely recognized eyebrow model was described by Westmore in 1974. With the rapidly changing concept of beauty, an accurate up-to-date model is needed. METHODS: The Westmore model was tested on fashion models that were randomly selected from the covers of the 1965-1975 (group 1) and 2006-2016 (group 2) Vogue magazine. The eyebrows of fashion models, which represent the beauty ideals of these decades, were objectively measured and compared. We proposed a modified eyebrow model more adapted to the modern standards of beauty, applied it to group 2, and objectively compared it to the Westmore model...
May 18, 2018: International Journal of Dermatology
https://www.readbyqxmd.com/read/29774415/development-of-a-cost-effective-production-process-for-halomonas-levan
#4
Burak Adnan Erkorkmaz, Onur Kırtel, Özlem Ateş Duru, Ebru Toksoy Öner
Levan polysaccharide is an industrially important natural polymer with unique properties and diverse high-value applications. However, current bottlenecks associated with its large-scale production need to be overcome by innovative approaches leading to economically viable processes. Besides many mesophilic levan producers, halophilic Halomonas smyrnensis cultures hold distinctive industrial potential and, for the first time with this study, the advantage of halophilicity is used and conditions for non-sterile levan production were optimized...
May 17, 2018: Bioprocess and Biosystems Engineering
https://www.readbyqxmd.com/read/29773387/levan-based-fibrous-scaffolds-electrospun-via-co-axial-and-single-needle-techniques-for-tissue-engineering-applications
#5
Gülben Avsar, Deniz Agirbasli, Mehmet Ali Agirbasli, Oguzhan Gunduz, Ebru Toksoy Oner
This represents the first systematic study where levan polysaccharide was used to fabricate fibrous matrices by co-axial and single-needle electrospinning techniques. For this, hydrolyzed (hHL) and sulfated hydrolyzed (ShHL) Halomonas levan were chemically synthesized and used together with polycaprolactone (PCL) and polyethyleneoxide (PEO) for the spinning process. In co-axially spun matrices, ultimate tensile strength (UTS) were found to increase with increasing ShHL concentration and elongation at break of PCL + ShHL matrices increased up to ten-fold when compared to PCL matrices...
August 1, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29769347/avian-influenza-viruses-in-wild-birds-virus-evolution-in-a-multi-host-ecosystem
#6
Divya Venkatesh, Marjolein J Poen, Theo M Bestebroer, Rachel D Scheuer, Oanh Vuong, Mzia Chkhaidze, Anna Machablishvili, Jimsher Mamuchadze, Levan Ninua, Nadia B Fedorova, Rebecca A Halpin, Xudong Lin, Amy Ransier, Timothy B Stockwell, David E Wentworth, Divya Kriti, Jayeeta Dutta, Harm van Bakel, Anita Puranik, Marek J Slomka, Steve Essen, Ian H Brown, Ron A M Fouchier, Nicola S Lewis
Wild ducks and gulls are the major reservoirs for avian influenza A viruses (AIVs). The mechanisms that drive AIV evolution are complex at sites where various duck and gull species from multiple flyways breed, winter or stage. The Republic of Georgia is located at the intersection of three migratory flyways: Central Asian Flyway, East Asian/East African Flyway and Black Sea/Mediterranean Flyway. For six consecutive years (2010-2016), we collected AIV samples from various duck and gull species that breed, migrate and overwinter in Georgia...
May 16, 2018: Journal of Virology
https://www.readbyqxmd.com/read/29753011/insights-into-hydrolysis-versus-transfructosylation-mutagenesis-studies-of-a-novel-levansucrase-from-brenneria-sp-enid312
#7
Wei Xu, Dawei Ni, Shuhuai Yu, Tao Zhang, Wanmeng Mu
Levan is a kind of fructan that composing of fructose by β-(2, 6) linkage and has been already applied as thickening agent and colloidal stabilizer in the cosmetic, medicinal and food industries. Microbial levansucrase is a key enzyme catalyzing the formation of levan from sucrose by transfructosylation. Here, a gene encoding levansucrase from Brenneria sp. EniD312 was cloned and expressed in Escherichia coli. The recombinant levansucrase showed the optimal pH and temperature at pH 6.5 and 45 °C. The enzyme produced 85 g/L levan from 250 g/L sucrose at pH 6...
May 9, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29733330/benefits-of-caloric-restriction-in-longevity-and-chemical-induced-tumorigenesis-are-transmitted-independent-of-nqo1
#8
Alberto Diaz-Ruiz, Andrea Di Francesco, Bethany A Carboneau, Sophia R Levan, Kevin J Pearson, Nathan L Price, Theresa M Ward, Michel Bernier, Rafael de Cabo, Evi M Mercken
Caloric restriction (CR) is the most potent nonpharmacological intervention known to both protect against carcinogenesis and delay aging in laboratory animals. There is a growing number of anticarcinogens and CR mimetics that activate NAD(P)H:quinone oxidoreductase 1 (NQO1). We have previously shown that NQO1, an antioxidant enzyme that acts as an energy sensor through modulation of intracellular redox and metabolic state, is upregulated by CR. Here, we used NQO1-knockout (KO) mice to investigate the role of NQO1 in both the aging process and tumor susceptibility, specifically in the context of CR...
May 4, 2018: Journals of Gerontology. Series A, Biological Sciences and Medical Sciences
https://www.readbyqxmd.com/read/29720402/structural-characterization-of-the-p-1-intermediate-state-of-the-p-cluster-of-nitrogenase
#9
Stephen M Keable, Oleg A Zadvornyy, Lewis E Johnson, Bojana Ginovska, Andrew J Rasmussen, Karamatullah Danyal, Brian J Eilers, Gregory A Prussia, Axl X LeVan, Simone Raugei, Lance C Seefeldt, John W Peters
Nitrogenase is the enzyme that reduces atmospheric dinitrogen (N2 ) to ammonia (NH3 ) in biological systems. It catalyzes a series of single-electron transfers from the donor iron protein (Fe protein) to the molybdenum-iron protein (MoFe protein) that contains the iron-molybdenum cofactor (FeMo-co) sites where N2 is reduced to NH3 The [8Fe-7S] P-cluster in the MoFe protein functions in nitrogenase catalysis as an intermediate electron carrier between the external electron donor, the Fe protein, and the FeMo-co sites of the MoFe protein...
May 2, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29712585/transarterial-radiation-lobectomy-portal-vein-embolization-and-staged-hepatectomy-for-multiple-bilobar-metachronous-colorectal-liver-metastasis
#10
Javier Augusto Arreaza, Levan Tsamalaidze, John Andrew Stauffer
No abstract text is available yet for this article.
April 1, 2018: American Surgeon
https://www.readbyqxmd.com/read/29712584/laparoscopic-cholecystectomy-for-mirizzi-syndrome-is-it-safe
#11
Javier Augusto Arreaza, Levan Tsamalaidze, John Andrew Stauffer
No abstract text is available yet for this article.
April 1, 2018: American Surgeon
https://www.readbyqxmd.com/read/29682474/pancreaticoduodenectomy-minimizing-the-learning-curve
#12
Levan Tsamalaidze, John A Stauffer
Background: Pancreaticoduodenectomy outcomes improve as surgeon experience increases. We analyzed the outcomes of pancreaticoduodenectomy for any improvements over time to assess the learning curve. Methods: A retrospective study of patients undergoing consecutive pancreaticoduodenectomy by a single surgeon at the beginning of practice was performed. Operative factors and 90-day outcomes were examined and trends over the course of the 4-year time period were analyzed...
2018: Journal of Visualized Surgery
https://www.readbyqxmd.com/read/29649388/the-genome-based-metabolic-systems-engineering-to-boost-levan-production-in-a-halophilic-bacterial-model
#13
Busra Aydin, Tugba Ozer, Ebru Toksoy Oner, Kazim Yalcin Arga
Metabolic systems engineering is being used to redirect microbial metabolism for the overproduction of chemicals of interest with the aim of transforming microbial hosts into cellular factories. In this study, a genome-based metabolic systems engineering approach was designed and performed to improve biopolymer biosynthesis capability of a moderately halophilic bacterium Halomonas smyrnensis AAD6T producing levan, which is a fructose homopolymer with many potential uses in various industries and medicine. For this purpose, the genome-scale metabolic model for AAD6T was used to characterize the metabolic resource allocation, specifically to design metabolic engineering strategies for engineered bacteria with enhanced levan production capability...
March 2018: Omics: a Journal of Integrative Biology
https://www.readbyqxmd.com/read/29580412/structural-characterization-of-the-exopolysaccharides-from-water-kefir
#14
Lea Fels, Frank Jakob, Rudi F Vogel, Daniel Wefers
Water kefir is a beverage which is produced by initiating fermentation of a fruit extract/sucrose solution with insoluble kefir grains. Exopolysaccharides that are formed from sucrose play a major role in the kefir grain formation, but the exopolysaccharides in the kefir beverage and the detailed structural composition of the whole kefir grains have not been studied yet. Therefore, kefir grains and the corresponding kefir beverage were analyzed for exopolysaccharides by multiple chromatographic approaches and two-dimensional NMR spectroscopy...
June 1, 2018: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29579045/from-correlation-to-causation-estimating-effective-connectivity-from-zero-lag-covariances-of-brain-signals
#15
Jonathan Schiefer, Alexander Niederbühl, Volker Pernice, Carolin Lennartz, Jürgen Hennig, Pierre LeVan, Stefan Rotter
Knowing brain connectivity is of great importance both in basic research and for clinical applications. We are proposing a method to infer directed connectivity from zero-lag covariances of neuronal activity recorded at multiple sites. This allows us to identify causal relations that are reflected in neuronal population activity. To derive our strategy, we assume a generic linear model of interacting continuous variables, the components of which represent the activity of local neuronal populations. The suggested method for inferring connectivity from recorded signals exploits the fact that the covariance matrix derived from the observed activity contains information about the existence, the direction and the sign of connections...
March 26, 2018: PLoS Computational Biology
https://www.readbyqxmd.com/read/29534758/tecs-a-toxin-expression-control-strategy-as-a-tool-for-optimization-of-inducible-promoters
#16
Aleksandra Małachowska, Paweł Olszewski
BACKGROUND: Transcriptional control of gene expression is a widely utilized regulatory mechanism in synthetic biology, biotechnology and recombinant protein production. It is achieved by utilization of naturally occurring promoters responding to nutrients or chemicals. Despite their regulatory properties, these promoters often possess features which diminish their utility for biotechnology. High basal expression level and low induction ratio can be removed using genetic engineering techniques, although this process is often laborious and time-consuming...
March 13, 2018: Microbial Cell Factories
https://www.readbyqxmd.com/read/29531683/phylogeography-and-taxonomic-status-of-trout-and-salmon-from-the-ponto-caspian-drainages-with-inferences-on-european-brown-trout-evolution-and-taxonomy
#17
Levan Ninua, David Tarkhnishvili, Elguja Gvazava
Current taxonomy of western Eurasian trout leaves a number of questions open; it is not clear to what extent some species are distinct genetically and morphologically. The purpose of this paper was to explore phylogeography and species boundaries in freshwater and anadromous trout from the drainages of the Black and the Caspian Seas (Ponto-Caspian). We studied morphology and mitochondrial phylogeny, combining samples from the western Caucasus within the potential range of five nominal species of trout that are thought to inhabit this region, and using the sequences available from GenBank...
March 2018: Ecology and Evolution
https://www.readbyqxmd.com/read/29527191/-pseudomonas-rhizophila-s211-a-new-plant-growth-promoting-rhizobacterium-with-potential-in-pesticide-bioremediation
#18
Wafa Hassen, Mohamed Neifar, Hanene Cherif, Afef Najjari, Habib Chouchane, Rim C Driouich, Asma Salah, Fatma Naili, Amor Mosbah, Yasmine Souissi, Noura Raddadi, Hadda I Ouzari, Fabio Fava, Ameur Cherif
A number of Pseudomonas strains function as inoculants for biocontrol, biofertilization, and phytostimulation, avoiding the use of pesticides and chemical fertilizers. Here, we present a new metabolically versatile plant growth-promoting rhizobacterium, Pseudomonas rhizophila S211, isolated from a pesticide contaminated artichoke field that shows biofertilization, biocontrol and bioremediation potentialities. The S211 genome was sequenced, annotated and key genomic elements related to plant growth promotion and biosurfactant (BS) synthesis were elucidated...
2018: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29518088/short-term-dynamics-of-the-sputum-microbiome-among-copd-patients
#19
Rohita Sinha, Lisa A Weissenburger-Moser, Jennifer L Clarke, Lynette M Smith, Art J Heires, Debra J Romberger, Tricia D LeVan
Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder characterized by incompletely reversible airflow obstruction. The complexity of the lung microbial community in COPD patients has been highlighted in recent years. Evidence suggests that transplantation, medications, age, and disease severity influence microbial community membership. However, the dynamics of the lung microbiome in stable COPD patients remain poorly understood. In this study, we completed a longitudinal 16S ribosomal RNA survey of the lung microbiome on replicate sputum samples collected from 4 former smokers with COPD (Stage 2) within a 2-day time period...
2018: PloS One
https://www.readbyqxmd.com/read/29497794/rational-designed-mutagenesis-of-levansucrase-from-bacillus-licheniformis-8-37-0-1-for-product-specificity-study
#20
Chunjuan He, Yirui Yang, Renfei Zhao, Jingyao Qu, Lan Jin, Lili Lu, Li Xu, Min Xiao
Levansucrases, which belong to the glycoside hydrolase family 68 (GH68), synthesize β (2-6)-linked fructan levan with sucrose as substrate. We described the use of a levansucrase (Bl_SacB) from Bacillus licheniformis 8-37-0-1 for catalysis of fructosyl transfer to obtain high levan yield previously. In the present study, six variants (Y246A, N251A, K372A, R369A, R369S, and R369K) were constructed through sequence alignment and structural analysis to explore the synthesis mechanism of Bl_SacB. The selected residues were predicted to localize to the substrate-entering channel of the active cavity and close to or remote from the catalytic triad...
April 2018: Applied Microbiology and Biotechnology
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