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https://www.readbyqxmd.com/read/28749518/the-mechanism-and-regioselectivities-of-nhc-nickel-ii-hydride-catalyzed-cycloisomerization-of-dienes-a-computational-study
#1
Yuan Gao, K N Houk, Chun-Yu Ho, Xin Hong
Transition metal-catalyzed hydroalkenylation is widely applied in organic synthesis to construct carbon-carbon bonds and synthesize substituted alkenes. In this work, the mechanism and regioselectivities of [(NHC)NiH](+)-catalyzed intramolecular cycloisomerization of dienes are studied by density functional theory (DFT) calculations. Through an initial hydride insertion, [(NHC)NiH](+) reacts with the diene substrate to generate the alkyl nickel species. This alkyl nickel species is the resting state of the catalytic cycle, and the hydroalkenylation reaction involves sequential olefin insertion and β-hydride transfer...
July 27, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28747360/cannabinoids-and-the-kidney-effects-in-health-and-disease
#2
Frank Park, Praveen K Potukuchi, Hamid Moradi, Csaba P Kovesdy
Consumption of cannabis and various related products (cannabinoids) for both medicinal and recreational use is gaining popularity. Furthermore, regulatory changes are fostering a cultural shift towards increasing liberalization of cannabis use, thereby increasing the likelihood of even larger numbers of individuals being exposed in the future. The two different types of receptors (CB1 and CB2) that are activated by the pharmacologically active ingredients of cannabis are found in numerous tissues, including the kidneys...
July 26, 2017: American Journal of Physiology. Renal Physiology
https://www.readbyqxmd.com/read/28745883/derivatization-of-phosphine-ligands-with-bulky-deltahedral-zintl-clusters-synthesis-of-charge-neutral-zwitterionic-tetrel-cluster-compounds-ge9-si-tms-3-2-t-bu2p-m-nhc-dipp-m-cu-ag-au
#3
Felix S Geitner, Jasmin V Dums, Thomas F Fässler
Reactions of silylated clusters [Ge9{Si(TMS)3}3](-) or [Ge9{Si(TMS)3}2](2-) with dialkylhalophosphines R2PCl (Cy, iPr, tBu) at ambient temperature yield the first tetrel Zintl cluster compounds bearing phosphine moieties. Varying reactivity of the dialkylhalophosphines towards the silylated clusters is observed depending on the bulkiness of the phosphine´s alkyl substituents and on the number of hypersilyl groups at the tetrel cluster. Reactions between phosphines with small cyclohexyl (Cy) or isopropyl- (iPr) groups and the tris-silylated cluster [Ge9{Si(TMS)3}3](-) yield the novel neutral cluster compounds [Ge9{Si(TMS)3}3PR2] (R: Cy (1), iPr (2)) with discrete Ge-P exo bonds...
July 26, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28741083/construction-of-bioengineered-yeast-platform-for-direct-bioethanol-production-from-alginate-and-mannitol
#4
Toshiyuki Takagi, Yusuke Sasaki, Keisuke Motone, Toshiyuki Shibata, Reiji Tanaka, Hideo Miyake, Tetsushi Mori, Kouichi Kuroda, Mitsuyoshi Ueda
Brown macroalgae are a sustainable and promising source for bioethanol production because they are abundant in ocean ecosystems and contain negligible quantities of lignin. Brown macroalgae contain cellulose, hemicellulose, mannitol, laminarin, and alginate as major carbohydrates. Among these carbohydrates, brown macroalgae are characterized by high levels of alginate and mannitol. The direct bioconversion of alginate and mannitol into ethanol requires extensive bioengineering of assimilation processes in the standard industrial microbe Saccharomyces cerevisiae...
July 24, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28740755/identifying-genes-and-regulatory-pathways-associated-with-the-scleractinian-coral-calcification-process
#5
Eldad Gutner-Hoch, Hiba Waldman Ben-Asher, Ruth Yam, Aldo Shemesh, Oren Levy
Reef building corals precipitate calcium carbonate as an exo-skeleton and provide substratum for prosperous marine life. Biomineralization of the coral's skeleton is a developmental process that occurs concurrently with other proliferation processes that control the animal extension and growth. The development of the animal body is regulated by large gene regulatory networks, which control the expression of gene sets that progressively generate developmental patterns in the animal body. In this study we have explored the gene expression profile and signaling pathways followed by the calcification process of a basal metazoan, the Red Sea scleractinian (stony) coral, Stylophora pistillata...
2017: PeerJ
https://www.readbyqxmd.com/read/28736352/the-effect-of-biocomposite-screws-on-bone-regeneration-in-a-rat-osteoporosis-model
#6
Je Hoon Jeong, Eun-Sun Jin, Ji Yeon Kim, Bora Lee, JoongKee Min, Sang Ryong Jeon, Minsu Lee, Kyoung Hyo Choi
INTRODUCTION: The aim of this study was to evaluate the efficacy of biocomposite screws used in ovariectomy (OVX) induced osteoporotic rats. METHODS: Twenty-four female Wistar rats (250-300g, 12 weeks old) were divided into 4 groups; Sham group (control), OVX-induced osteoporosis group (OVX), OVX and biodegradable (PLGA (poly-lactic-co-glycolic acid) without ß-TCP (tricalcium phosphate) screw insertion group (OVX/BSR), OVX and biocomposite (PLGA with ß-TCP) screw insertion group (OVX/CSR)...
July 20, 2017: World Neurosurgery
https://www.readbyqxmd.com/read/28733198/the-role-of-intrinsic-disorder-and-dynamics-in-the-assembly-and-function-of-the-type-ii-secretion-system
#7
REVIEW
Shuang Gu, Vladimir E Shevchik, Rosie Shaw, Richard W Pickersgill, James A Garnett
Many Gram-negative commensal and pathogenic bacteria use a type II secretion system (T2SS) to transport proteins out of the cell. These exported proteins or substrates play a major role in toxin delivery, maintaining biofilms, replication in the host and subversion of host immune responses to infection. We review the current structural and functional work on this system and argue that intrinsically disordered regions and protein dynamics are central for assembly, exo-protein recognition, and secretion competence of the T2SS...
July 18, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28731303/lead-ii-binding-in-natural-and-artificial-proteins
#8
Virginia Cangelosi, Leela Ruckthong, Vincent L Pecoraro
This article describes recent attempts to understand the biological chemistry of lead using a synthetic biology approach. Lead binds to a variety of different biomolecules ranging from enzymes to regulatory and signaling proteins to bone matrix. We have focused on the interactions of this element in thiolate-rich sites that are found in metalloregulatory proteins such as Pbr, Znt, and CadC and in enzymes such as δ-aminolevulinic acid dehydratase (ALAD). In these proteins, Pb(II) is often found as a homoleptic and hemidirectic Pb(II)(SR)3- complex...
April 10, 2017: Metal Ions in Life Sciences
https://www.readbyqxmd.com/read/28729721/plasma-derived-exosome-characterization-reveals-a-distinct-microrna-signature-in-long-duration-type-1-diabetes
#9
Marta Garcia-Contreras, Sanket H Shah, Alejandro Tamayo, Paul D Robbins, Ronald B Golberg, Armando J Mendez, Camillo Ricordi
Type 1 diabetes mellitus (T1DM) results from an autoimmune attack against the insulin-producing ß cells which leads to chronic hyperglycemia. Exosomes are lipid vesicles derived from cellular multivesicular bodies that are enriched in specific miRNAs, potentially providing a disease-specific diagnostic signature. To assess the value of exosome miRNAs as biomarkers for T1DM, miRNA expression in plasma-derived exosomes was measured. Nanoparticle tracking analysis and transmission electron microscopy confirmed the presence of plasma-derived exosomes (EXOs) isolated by differential centrifugation...
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28726419/hitoyol-a-and-b-two-norsesquiterpenoids-from-the-basidiomycete-coprinopsis-cinerea
#10
Junnosuke Otaka, Daisuke Hashizume, Yui Masumoto, Atsuya Muranaka, Masanobu Uchiyama, Hiroyuki Koshino, Yushi Futamura, Hiroyuki Osada
Hitoyol A (1), an unprecedented norsesquiterpenoid with an exo-tricyclo[5.2.1.0(2,6)]decane skeleton, was isolated from the culture broth of Basidiomycete Coprinopsis cinerea along with a novel skeletal hitoyol B (2) containing 4-cyclopentene-1,3-dione. Their structures and absolute configurations were analyzed by single-crystal X-ray diffraction and electronic circular dichroism spectroscopic methods. Compound 1 is possibly biosynthesized through decarboxylation-induced cyclization of lagopodin B, a known cuparene-type sesquiterpenoid...
July 20, 2017: Organic Letters
https://www.readbyqxmd.com/read/28726373/ultrasensitive-homogeneous-electrochemical-detection-of-transcription-factor-by-coupled-isothermal-cleavage-reaction-and-cycling-amplification-based-on-exonuclease-iii
#11
Lihua Lu, Huijuan Su, Feng Li
The assay and monitoring of transcription factors (TFs) has attracted extensive attention, due to their important roles in regulation of gene expressions. Herein, a simple, low cost, rapid, and highly sensitive homogeneous electrochemical method utilizing the coupled isothermal cleavage reaction and cycling amplification based on exonuclease III (Exo III) was explored for the analysis of transcription factor NF-κB p50 in aqueous solution. In the assay, a 3-methylene blue (MB)-labeled hairpin probe is designed, which can be opened up by the single stranded DNA (ssDNA) protected by NF-κB p50 from the Exo III cleavage, to trigger the subsequent Exo III-assisted digestion, thus a large amount of MB-labeled mononucleotides are liberated to result in the greatly amplified electrochemical signal...
July 20, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28719201/silver-catalyzed-cascade-1-6-addition-cyclization-of-para-quinone-methides-with-propargyl-malonates-an-approach-to-spiro-4-5-deca-6-9-dien-8-ones
#12
Zhenbo Yuan, Lina Liu, Rui Pan, Hequan Yao, Aijun Lin
An unprecedented silver-catalyzed cascade 1,6-addition/5-exo-dig cyclization reaction between para-quinone methides and propargyl malonates under mild reaction conditions has been described. This reaction provides an efficient method to construct versatile spiro[4.5]cyclohexadienones in moderate to excellent yields with high atom economy and scalability.
July 18, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28718484/palladium-catalyzed-dearomatizative-2-2-1-carboannulation-of-1-7-enynes-with-aryl-diazonium-salts-and-h2o-facile-synthesis-of-spirocyclohexadienone-fused-cyclopenta-c-quinolin-4-5h-ones
#13
Yu Liu, Ren-Jie Song, Jin-Heng Li
A new palladium-catalyzed dearomatizative [2 + 2 + 1] carboannulation of 1,7-enynes with aryl diazonium salts and H2O is presented. The reaction enables the construction of spirocyclohexadienone-fused cyclopenta[c]quinolin-4(5H)-ones through a sequence of Heck-type addition, 6-exo-dig cyclization, ipso-cyclization, dearomatization and hydrolysis.
July 27, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28708388/ni-catalyzed-alkene-carboacylation-via-amide-c-n-bond-activation
#14
James A Walker, Kevin L Vickerman, Jenna N Humke, Levi M Stanley
We report Ni-catalyzed formal carboacylation of o-allylbenzamides with arylboronic acid pinacol esters. The reaction is triggered by oxidative addition of an activated amide C-N bond to a Ni(0) catalyst and proceeds via alkene insertion into a Ni(II)-acyl bond. The exo-selective carboacylation reaction generates 2-benzyl-2,3-dihydro-1H-inden-1-ones in moderate to high yields (46-99%) from a variety of arylboronic acid pinacol esters and substituted o-allylbenzamides. These results show that amides are practical substrates for alkene carboacylation via amide C-N bond activation, and this approach bypasses challenges associated with alkene carboacylation triggered by C-C bond activation...
July 20, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28708291/total-syntheses-of-the-reported-structures-of-curcusone-i-and-j-via-tandem-gold-catalysis
#15
Yong Li, Mingji Dai
Total syntheses of the reported structures of the rhamnofolane diterpene natural products curcusone I and J in racemic forms have been achieved. The synthetic strategy features a novel tandem gold-catalyzed furan formation and furan-allene [4+3] cycloaddition to build the 5,7-fused ring system with an oxa-bridge in one step and a stereoselective exo-Diels-Alder reaction to form the 6-membered ring. The newly developed tandem gold catalysis is quite general and can be scaled up. Our syntheses suggested that structural revisions of curcusone I and J are needed...
July 14, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28706488/postnatal-maturation-of-the-glomerular-filtration-rate-in-conventional-growing-piglets-as-potential-juvenile-animal-model-for-preclinical-pharmaceutical-research
#16
Elke Gasthuys, Mathias Devreese, Joske Millecam, Stanislas Sys, Katrien Vanderperren, Joris Delanghe, Johan Vande Walle, Marjolein Heyndrickx, Siska Croubels
Adequate animal models are required to study the preclinical pharmacokinetics (PK), pharmacodynamics (PD) and safety of drugs in the pediatric subpopulation. Over the years, pigs were presented as a potential animal model, since they display a high degree of anatomical and physiological similarities with humans. To assess the suitability of piglets as a preclinical animal model for children, the ontogeny and maturation processes of several organ systems have to be unraveled and compared between both species...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28698583/ammonium-chloride-alters-neuronal-excitability-and-synaptic-vesicle-release
#17
Roman M Lazarenko, Claire E DelBove, Claire E Strothman, Qi Zhang
Genetically encoded pH-sensors are widely used in studying cell membrane trafficking and membrane protein turnover because they render exo-/endocytosis-associated pH changes to fluorescent signals. For imaging and analysis purposes, high concentration ammonium chloride is routinely used to alkalize intracellular membrane compartments under the assumption that it does not cause long-term effects on cellular processes being studied like neurotransmission. However, pathological studies about hyperammonemia have shown that ammonium is toxic to brain cells especially astrocytes and neurons...
July 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28698247/carbohydrate-binding-architecture-of-the-multi-modular-%C3%AE-1-6-glucosyltransferase-from%C3%A2-paenibacillus-sp-598k-which-produces-%C3%AE-1-6-glucosyl-%C3%AE-glucosaccharides-from-starch
#18
Zui Fujimoto, Nobuhiro Suzuki, Naomi Kishine, Hitomi Ichinose, Mitsuru Momma, Atsuo Kimura, Kazumi Funane
Paenibacillus sp. 598K α-1,6-glucosyltransferase (Ps6TG31A), a member of glycoside hydrolase family 31, catalyzes exo-α-glucohydrolysis and transglucosylation and produces α-1,6-glucosyl-α-glucosaccharides from α-glucan via its disproportionation activity. The crystal structure of Ps6TG31A was determined by an anomalous dispersion method using a terbium derivative. The monomeric Ps6TG31A consisted of one catalytic (β/α)8-barrel domain and six small domains, one on the N-terminal, and five on the C-terminal side...
July 11, 2017: Biochemical Journal
https://www.readbyqxmd.com/read/28690087/an-exo-probe-based-recombinase-polymerase-amplification-assay-for-the-rapid-detection-of-porcine-parvovirus
#19
Jian-Chang Wang, Li-Bing Liu, Qing-An Han, Jin-Feng Wang, Wan-Zhe Yuan
Recombinase polymerase amplification (RPA), an isothermal amplification technology, has been developed as an alternative to PCR in pathogen detection. A real-time RPA assay (rt-RPA) was developed to detect the porcine parvovirus (PPV) using primers and exo probe specific for the VP2 gene. The amplification was performed at 39°C for 20min. There was no cross-reaction with other pathogens tested. Using the recombinant plasmid pPPV-VP2 as template, the analytical sensitivity was 103 copies. The assay performance was evaluated by testing 115 field samples by rt-RPA and a real-time PCR assay...
July 6, 2017: Journal of Virological Methods
https://www.readbyqxmd.com/read/28688309/programmable-strand-displacement-based-magnetic-separation-for-simultaneous-amplified-detection-of-multiplex-micrornas-by-chemiluminescence-imaging-array
#20
Shuzhen Yue, Tingting Zhao, Sai Bi, Zhipeng Zhang
High throughput analysis of miRNAs is of great significance to clinical and biomedical applications. In this work, we have developed a highly sensitive and selective chemiluminescence imaging array (CLIA) for simultaneous detection of three miRNAs with high throughput, easy operation and low cost. In this assay, three kinds of hairpins that can specially recognize respective miRNAs (miR-155, miR-let-7a and miR-141) are parallel modified on the magnetic beads (MBs). The employment of MBs enables quick sorting of multiplex targets in high yield and purity with high throughput...
June 28, 2017: Biosensors & Bioelectronics
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