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https://www.readbyqxmd.com/read/30544837/magnetoconductivity-and-terahertz-response-of-a-hgcdte-epitaxial-layer
#1
Dmitriy Yavorskiy, Krzysztof Karpierz, Michał Baj, Małgorzata M Bąk, Nikolai N Mikhailov, Sergey A Dvoretsky, Vladimir I Gavrilenko, Wojciech Knap, Frederic Teppe, Jerzy Usakowski
An epitaxial layer of HgCdTe-a THz detector-was studied in magnetotransmission, magnetoconductivity and magnetophotoconductivity experiments at cryogenic temperatures. In the optical measurements, monochromatic excitation with photon frequency ranging from 0.05 THz to 2.5 THz was used. We show a resonant response of the detector at magnetic fields as small as 10 mT with the width of the resonant line equal to about 5 mT. Application of a circular polarizer at 2.5 THz measurements allowed for confirming selection rules predicted by the theory of optical transitions in a narrow-gap semiconductor and to estimate the band-gap to be equal to about 4...
December 8, 2018: Sensors
https://www.readbyqxmd.com/read/30457115/radiative-recombination-in-narrow-gap-hgte-cdhgte-quantum-well-heterostructures-for-laser-applications
#2
V Ya Aleshkin, A A Dubinov, V V Rumyantsev, M A Fadeev, O L Domnina, N N Mikhailov, S A Dvoretsky, F Teppe, V I Gavrilenko, S V Morozov
Radiative recombination is studied in CdHgTe/HgTe QWs with bandgap in the 40-140 meV range using four-band Kane model. Calculated radiative lifetimes agree well with the photoconductivity kinetics measurements. We show that the side maxima in the valence band hinder the radiative recombination at high carrier concentrations and discuss how to overcome this effect for the development of long-wavelength lasers.
December 12, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/30355669/isolation-and-characterization-of-the-novel-botulinum-neurotoxin-a-subtype-6
#3
Molly S Moritz, William H Tepp, Marite Bradshaw, Eric A Johnson, Sabine Pellett
Botulinum neurotoxins (BoNTs), the most potent toxins known to humans and the causative agent of botulism, exert their effect by entering motor neurons and cleaving and inactivating SNARE proteins, which are essential for neurotransmitter release. BoNTs are proven, valuable pharmaceuticals used to treat more than 200 neuronal disorders. BoNTs comprise 7 serotypes and more than 40 isoforms (subtypes). BoNT/A1 is the only A-subtype used clinically due to its high potency and long duration of action. While other BoNT/A subtypes have been purified and described, only BoNT/A2 is being investigated as an alternative to BoNT/A1...
October 24, 2018: MSphere
https://www.readbyqxmd.com/read/30261663/intracellular-energy-transfer-networks-and-high-resolution-respirometry-a-convenient-approach-for-studying-their-function
#4
REVIEW
Marju Puurand, Kersti Tepp, Aleksandr Klepinin, Lyudmila Klepinina, Igor Shevchuk, Tuuli Kaambre
Compartmentalization of high-energy phosphate carriers between intracellular micro-compartments is a phenomenon that ensures efficient energy use. To connect these sites, creatine kinase (CK) and adenylate kinase (AK) energy-transfer networks, which are functionally coupled to oxidative phosphorylation (OXPHOS), could serve as important regulators of cellular energy fluxes. Here, we introduce how selective permeabilization of cellular outer membrane and high-resolution respirometry can be used to study functional coupling between CK or AK pathways and OXPHOS in different cells and tissues...
September 26, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/30058357/comparative-analysis-of-the-bioenergetics-of-human-adenocarcinoma-caco-2-cell-line-and-postoperative-tissue-samples-from-colorectal-cancer-patients
#5
Lyudmila Ounpuu, Laura Truu, Igor Shevchuk, Vladimir Chekulayev, Aleksandr Klepinin, Andre Koit, Kersti Tepp, Marju Puurand, Egle Rebane-Klemm, Tuuli Käämbre
The aim of this work was to explore the key bioenergetic properties for mitochondrial respiration in the widely-used Caco-2 cell line and in human colorectal cancer (HCC) postoperational tissue samples. Oxygraphy and metabolic control analysis (MCA) were applied to estimate the function of oxidative phosphorylation in cultured Caco-2 cells and HCC tissue samples. The mitochondria of Caco-2 cells and HCC tissues displayed larger functional activity of respiratory complex (C)II compared with CI, whereas in normal colon tissue an inverse pattern in the ratio of CI to CII activity was observed...
July 30, 2018: Biochemistry and Cell Biology, Biochimie et Biologie Cellulaire
https://www.readbyqxmd.com/read/30014523/the-dual-state-luminescent-mechanism-of-2-3-4-5-tetraphenyl-1h-pyrrole
#6
Yunxiang Lei, Qianwei Liu, Lichao Dong, Zhengxu Cai, Jianbing Shi, Junge Zhi, Bin Tong, Yuping Dong
2,3,4,5-Tetraphenyl-1H-pyrrole (TePP) was synthesized by a simple one-step reaction. The compound showed a balanced emission in both the solution and solid state with the absolute quantum yield of ΦF/THF =65.6 % and ΦF/solid =74.3 %, respectively. Temperature and viscosity variation measurements demonstrated that the phenyl group at the 1-position (N-position) of the pyrrole core can act as a rotor in pyrrole-based molecules, which can consume the excited energy and reduce the molecular emission in solution...
September 20, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29998379/the-complexity-of-mitochondrial-outer-membrane-permeability-and-vdac-regulation-by-associated-proteins
#7
Aleksandr Klepinin, Lyudmila Ounpuu, Kati Mado, Laura Truu, Vladimir Chekulayev, Marju Puurand, Igor Shevchuk, Kersti Tepp, Anu Planken, Tuuli Kaambre
Previous studies have shown that class II β-tubulin plays a key role in the regulation of oxidative phosphorylation (OXPHOS) in some highly differentiated cells, but its role in malignant cells has remained unclear. To clarify these aspects, we compared the bioenergetic properties of HL-1 murine sarcoma cells, murine neuroblastoma cells (uN2a) and retinoic acid - differentiated N2a cells (dN2a). We examined the expression and possible co-localization of mitochondrial voltage dependent anion channel (VDAC) with hexokinase-2 (HK-2) and βII-tubulin, the role of depolymerized βII-tubuline and the effect of both proteins in the regulation of mitochondrial outer membrane (MOM) permeability...
July 12, 2018: Journal of Bioenergetics and Biomembranes
https://www.readbyqxmd.com/read/29725617/quantum-spin-hall-insulator-with-a-large-bandgap-dirac-fermions-and-bilayer-graphene-analog
#8
Sergey S Krishtopenko, Frédéric Teppe
The search for room temperature quantum spin Hall insulators (QSHIs) based on widely available materials and a controlled manufacturing process is one of the major challenges of today's topological physics. We propose a new class of semiconductor systems based on multilayer broken-gap quantum wells, in which the QSHI gap reaches 60 meV and remains insensitive to temperature. Depending on their layer thicknesses and geometry, these novel structures also host a graphene-like phase and a bilayer graphene analog...
April 2018: Science Advances
https://www.readbyqxmd.com/read/29588398/the-light-chain-defines-the-duration-of-action-of-botulinum-toxin-serotype-a-subtypes
#9
Sabine Pellett, Marite Bradshaw, William H Tepp, Christina L Pier, Regina C M Whitemarsh, Chen Chen, Joseph T Barbieri, Eric A Johnson
Botulinum neurotoxin (BoNT) is the causative agent of botulism and a widely used pharmaceutical to treat a variety of neurological diseases. BoNTs are 150-kDa protein toxins organized into heavy chain (HC) and light chain (LC) domains linked by a disulfide bond. The HC selectively binds to neurons and aids cell entry of the enzymatically active LC. There are seven immunological BoNT serotypes (A to G); each serotype includes genetic variants, termed subtypes. Only two subtypes, BoNT/A1 and BoNT/B1, are currently used as therapeutics...
March 27, 2018: MBio
https://www.readbyqxmd.com/read/29543000/temperature-induced-topological-phase-transition-in-hgte-quantum-wells
#10
A M Kadykov, S S Krishtopenko, B Jouault, W Desrat, W Knap, S Ruffenach, C Consejo, J Torres, S V Morozov, N N Mikhailov, S A Dvoretskii, F Teppe
We report a direct observation of temperature-induced topological phase transition between the trivial and topological insulator states in an HgTe quantum well. By using a gated Hall bar device, we measure and represent Landau levels in fan charts at different temperatures, and we follow the temperature evolution of a peculiar pair of "zero-mode" Landau levels, which split from the edge of electronlike and holelike subbands. Their crossing at a critical magnetic field B_{c} is a characteristic of inverted band structure in the quantum well...
February 23, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29273248/substrate-cleavage-and-duration-of-action-of-botulinum-neurotoxin-type-fa-h-ha
#11
Sabine Pellett, William H Tepp, Guangyun Lin, Eric A Johnson
Botulinum neurotoxin (BoNT) type FA is the only known naturally occurring chimeric BoNT of domains of BoNT/A and BoNT/F. BoNT/FA consists of an F5-like light chain (LC), a unique heavy chain (HC) translocation domain, and a HC receptor binding domain similar to BoNT/A1. Previous analyses of purified BoNT/FA have indicated a 5-10-fold greater potency in cultured human or rat neurons as compared to BoNT/A1 and a 400-500-fold greater potency compared to BoNT/B1. However, in vivo potency in mice was about 5-fold lower than BoNT/A1 or/B1...
June 1, 2018: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/29207616/pkm2-activation-sensitizes-cancer-cells-to-growth-inhibition-by-2-deoxy-d-glucose
#12
Sui Seng Tee, Jae Mo Park, Ralph E Hurd, Kyle R Brimacombe, Matthew B Boxer, Tarik F Massoud, Brian K Rutt, Daniel M Spielman
Cancer metabolism has emerged as an increasingly attractive target for interfering with tumor growth. Small molecule activators of pyruvate kinase isozyme M2 (PKM2) suppress tumor formation but have an unknown effect on established tumors. We demonstrate that TEPP-46, a PKM2 activator, results in increased glucose consumption, providing the rationale for combining PKM2 activators with the toxic glucose analog, 2-deoxy-D-glucose (2-DG). Combination treatment resulted in reduced viability of a range of cell lines in standard cell culture conditions at concentrations of drugs that had no effect when used alone...
October 31, 2017: Oncotarget
https://www.readbyqxmd.com/read/29158482/structural-basis-for-the-unique-ganglioside-and-cell-membrane-recognition-mechanism-of-botulinum-neurotoxin-dc
#13
Sicai Zhang, Ronnie P-A Berntsson, William H Tepp, Liang Tao, Eric A Johnson, Pål Stenmark, Min Dong
Botulinum neurotoxins (BoNTs), the most potent toxins known, are potential bioterrorism agents. It is well established that all seven serotypes of BoNTs (BoNT/A-G) require complex gangliosides as co-receptors. Here, we report that BoNT/DC, a presumed mosaic toxin between BoNT/D and BoNT/C1, binds and enters efficiently into neurons lacking complex gangliosides and shows no reduction in toxicity in mice deficient in complex gangliosides. The co-crystal structure of BoNT/DC with sialyl-Thomsen-Friedenreich antigen (Sialyl-T) suggests that BoNT/DC recognizes only the sialic acid, but not other moieties in gangliosides...
November 21, 2017: Nature Communications
https://www.readbyqxmd.com/read/29124194/metabolic-remodeling-in-human-colorectal-cancer-and-surrounding-tissues-alterations-in-regulation-of-mitochondrial-respiration-and-metabolic-fluxes
#14
Vladimir Chekulayev, Kati Mado, Igor Shevchuk, Andre Koit, Andrus Kaldma, Aleksandr Klepinin, Natalja Timohhina, Kersti Tepp, Manana Kandashvili, Lyudmila Ounpuu, Karoliina Heck, Laura Truu, Anu Planken, Vahur Valvere, Tuuli Kaambre
The aim of the work was to evaluate whether or not there is glycolytic reprogramming in the neighboring cells of colorectal cancer (CRC). Using postoperative material we have compared the functional capacity of oxidative phosphorylation (OXPHOS) in CRC cells, their glycolytic activity and their inclination to aerobic glycolysis, with those of the surrounding and healthy colon tissue cells. Experiments showed that human CRC cannot be considered a hypoxic tumor, since the malignancy itself and cells surrounding it exhibited even higher rates of OXPHOS than healthy large intestine...
December 2015: Biochemistry and Biophysics Reports
https://www.readbyqxmd.com/read/29016145/terahertz-detection-and-imaging-using-graphene-ballistic-rectifiers
#15
Gregory Auton, Dmytro B But, Jiawei Zhang, Ernie Hill, Dominique Coquillat, Christophe Consejo, Philippe Nouvel, Wojciech Knap, Luca Varani, Frederic Teppe, Jeremie Torres, Aimin Song
A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a rectenna as a terahertz (THz) detector. A small-area (<1 μm2 ) local gate is used to adjust the Fermi level in the device to optimize the output while minimizing the impact on the cutoff frequency. The device operates in both n- and p-type transport regimes and shows a peak extrinsic responsivity of 764 V/W and a corresponding noise equivalent power of 34 pW Hz-1/2 at room temperature with no indications of a cutoff frequency up to 0...
November 8, 2017: Nano Letters
https://www.readbyqxmd.com/read/28874316/la-teppe-the-epilepsy-center-tain-l-hermitage-france
#16
Oguz Omay, Jérôme Petit, François Luiggi
No abstract text is available yet for this article.
November 2017: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/28865127/evaluation-of-an-acute-oral-gavage-method-for-assessment-of-pesticide-toxicity-in-terrestrial-amphibians
#17
Douglas J Fort, Michael B Mathis, Faith Kee, Paul Whatling, David Clerkin, Jane Staveley, Clifford Habig
Development of an acute oral toxicity test with a terrestrial-phase amphibian was considered necessary to remove the uncertainty within the field of agrochemical risk assessments. The bullfrog (Lithobates catesbeianus) was selected for use as it is a representative of the family Ranidae and historically this species has been used as an amphibian test model species. Prior to definitive study, oral gavage methods were developed with fenthion and tetraethyl pyrophosphate. Dimethoate and malathion were subsequently tested with both male and female juvenile bullfrogs in comprehensive acute oral median lethal dose (LD50) studies...
February 2018: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/28781720/mitochondrial-respiration-in-human-colorectal-and-breast-cancer-clinical-material-is-regulated-differently
#18
Andre Koit, Igor Shevchuk, Lyudmila Ounpuu, Aleksandr Klepinin, Vladimir Chekulayev, Natalja Timohhina, Kersti Tepp, Marju Puurand, Laura Truu, Karoliina Heck, Vahur Valvere, Rita Guzun, Tuuli Kaambre
We conducted quantitative cellular respiration analysis on samples taken from human breast cancer (HBC) and human colorectal cancer (HCC) patients. Respiratory capacity is not lost as a result of tumor formation and even though, functionally, complex I in HCC was found to be suppressed, it was not evident on the protein level. Additionally, metabolic control analysis was used to quantify the role of components of mitochondrial interactosome. The main rate-controlling steps in HBC are complex IV and adenine nucleotide transporter, but in HCC, complexes I and III...
2017: Oxidative Medicine and Cellular Longevity
https://www.readbyqxmd.com/read/28744480/the-effector-tepp-mediates-recruitment-and-activation-of-phosphoinositide-3-kinase-on-early-chlamydia-trachomatis-vacuoles
#19
Victoria Carpenter, Yi-Shan Chen, Lee Dolat, Raphael H Valdivia
Chlamydia trachomatis delivers multiple type 3 secreted effector proteins to host epithelial cells to manipulate cytoskeletal functions, membrane dynamics, and signaling pathways. TepP is the most abundant effector protein secreted early in infection, but its molecular function is poorly understood. In this report, we provide evidence that TepP is important for bacterial replication in cervical epithelial cells, activation of type I IFN genes, and recruitment of class I phosphoinositide 3-kinases (PI3K) and signaling adaptor protein CrkL to nascent pathogen-containing vacuoles (inclusions)...
July 2017: MSphere
https://www.readbyqxmd.com/read/28698055/small-molecule-metalloprotease-inhibitor-with-in-vitro-ex-vivo-and-in-vivo-efficacy-against-botulinum-neurotoxin-serotype-a
#20
Alan R Jacobson, Michael Adler, Nicholas R Silvaggi, Karen N Allen, Genessa M Smith, Ross A Fredenburg, Ross L Stein, Jong-Beak Park, Xiaochuan Feng, Charles B Shoemaker, Sharad S Deshpande, Michael C Goodnough, Carl J Malizio, Eric A Johnson, Sabine Pellett, William H Tepp, Saul Tzipori
Botulinum neurotoxins (BoNTs) are the most toxic substances known to mankind and are the causative agents of the neuroparalytic disease botulism. Their ease of production and extreme toxicity have caused these neurotoxins to be classified as Tier 1 bioterrorist threat agents and have led to a sustained effort to develop countermeasures to treat intoxication in case of a bioterrorist attack. While timely administration of an approved antitoxin is effective in reducing the severity of botulism, reversing intoxication requires different strategies...
October 2017: Toxicon: Official Journal of the International Society on Toxinology
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