840 results on '"Regina M"'
Search Results
2. NON-MODIFIED PT ELECTRODES ENABLING ACCURATE VOLTAMMETRIC QUANTIFICATION OF AMMONIA IN WATER SAMPLES
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Vitoria B. Messias, Regina M. Takeuchi, and André L. Santos
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aquatic chemistry ,nitrogen cycle ,water quality ,Chemistry ,QD1-999 - Abstract
Even though ammonia is a natural component of aquatic environments, elevated concentrations indicate pollution and environmental degradation. Consequently, efficient analytical methods for monitoring ammonia levels are crucial for preserving water quality. Voltammetry offers a sustainable approach for NH3 quantification, combining good analytical performance with low sample and reagent consumption, minimizing waste generation. However, despite these advantages, the voltammetric determination of ammonia remains relatively unexplored. Therefore, this study investigated the electrochemical behavior of NH3 in alkaline solutions using a non-modified Pt electrode and evaluated the performance of differential pulse voltammetry (DPV) and square wave voltammetry (SWV) for NH3 determination. DPV provided superior performance, with limits of detection and quantification of 0.79 µmol L-1 (0.011 ppmN) and 2.6 µmol L-1 (0.036 ppmN), respectively, which comply with the maximum allowable ammonia concentration in natural waters according to Brazilian and European regulations. The voltammetric method successfully quantified ammonia in tap and river water samples, providing results concordant with the established Berthelot spectrophotometric method, at a 95% confidence level. Additionally, it is simple and fully accessible to non-electrochemist since no sophisticated procedures for electrode modification are needed. Finally, the high analytical performance of the proposed method makes it valuable for pollution monitoring in aquatic environments.
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- 2024
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3. FATORES DE EMISSÃO E DE ENRIQUECIMENTO DA CROSTA PARA ELEMENTOS TRAÇO (MP2,5) EMITIDOS PELA FROTA VEICULAR NA REGIÃO METROPOLITANA DE SÃO PAULO, BRASIL
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Juan R. S. Benatti, Pedro J. Pérez-Martínez, and Regina M. Miranda
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Chemistry ,QD1-999 - Abstract
Air pollution can cause several negative impacts on health and the environment. In large urban centers, this pollution is directly related to anthropogenic activities, mainly activities in the transportation sector. This study analyzed data on black carbon, fine particulate material (PM2.5) and its main trace elements from automotive vehicles (S, P, K, V, Cr, Fe, Cu, Ni, Zn, Cd, Br and Pb), collected during a long sampling period, carried out in the Metropolitan Area of São Paulo (MASP), Brazil. The filters used were analyzed by various analytical techniques, enabling the identification of the different elements present in the samples, their respective concentrations and the main sources of these pollutants and their contributions to the sampled total. Thus, it was possible to separate the total contributions of each source and use only the contributions of anthropogenic origin to define the emission factors (EF) and the crustal enrichment factors (EFc) for the different studied pollutants. We used these factors to compare different environments/studies. We chose two studies carried out previously, also in the MASP, in the Jânio Quadros (TJQ) and Rodoanel (TRA) tunnels, and found that these tunnels are respectively 2.3 and 3.8 times more polluted than the region from our study.
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- 2022
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4. Formation of Diacetyl and Other α‑Dicarbonyl Compounds during the Generation of E‑Vapor Product Aerosols
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Matt S. Melvin, Karen C. Avery, Regina M. Ballentine, Jason W. Flora, William Gardner, Georgios D. Karles, Yezdi B. Pithawalla, Donna C. Smith, Kimberly D. Ehman, and Karl A. Wagner
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Chemistry ,QD1-999 - Published
- 2020
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5. Design, Synthesis, and Targeted Delivery of Fluorescent 1,2,4-Triazole–Peptide Conjugates to Pediatric Brain Tumor Cells
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Muhammad Ajmal, Uzma Yunus, Regina M. Graham, and Roger M. Leblanc
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Chemistry ,QD1-999 - Published
- 2019
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6. AVALIAÇÃO DO PERFIL DE LIBERAÇÃO DO FÁRMACO IBUPROFENO EM MEMBRANAS SIMÉTRICAS E ASSIMÉTRICAS DE ACETATO DE CELULOSE: EFEITO DA MORFOLOGIA
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Marcos V. Ferreira, Lauro A. Pradela Filho, André L. dos Santos, Regina M. Takeuchi, and Rosana M. N. de Assunção
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Chemistry ,QD1-999 - Published
- 2019
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7. Encapsulation of Luminescent Gold Nanoclusters into Synthetic Vesicles
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Regina M. Chiechio, Solène Ducarre, Célia Marets, Aurélien Dupont, Pascale Even-Hernandez, Xavier Pinson, Stéphanie Dutertre, Franck Artzner, Paolo Musumeci, Célia Ravel, Maria Jose Lo Faro, and Valérie Marchi
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gold nanoclusters ,vesicles ,encapsulation ,Chemistry ,QD1-999 - Abstract
Gold nanoclusters (Au NCs) are attractive luminescent nanoprobes for biomedical applications. In vivo biosensing and bioimaging requires the delivery of the Au NCs into subcellular compartments. In this view, we explore here the possible encapsulation of ultra-small-sized red and blue emitting Au NCs into liposomes of various sizes and chemical compositions. Different methods were investigated to prepare vesicles containing Au NCs in their lumen. The efficiency of the process was correlated to the structural and morphological aspect of the Au NCs’ encapsulating vesicles thanks to complementary analyses by SAXS, cryo-TEM, and confocal microscopy techniques. Cell-like-sized vesicles (GUVs) encapsulating red or blue Au NCs were successfully obtained by an innovative method using emulsion phase transfer. Furthermore, exosome-like-sized vesicles (LUVs) containing Au NCs were obtained with an encapsulation yield of 40%, as estimated from ICP-MS.
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- 2022
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8. On the Water-Soluble Organic Matter in Inhalable Air Particles: Why Should Outdoor Experience Motivate Indoor Studies?
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Regina M. B. O. Duarte and Armando C. Duarte
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organic aerosols ,water-soluble organic matter ,outdoor air particles ,indoor air chemistry ,chemical characterization ,oxidative potential ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
The current understanding of water-soluble organic aerosol (OA) composition, sources, transformations, and effects is still limited to outdoor scenarios. However, the OA is also an important component of particulate matter indoors, whose complexity impairs a full structural and molecular identification. The current limited knowledge on indoor OA, and particularly on its water-soluble organic matter (WSOM) fraction is the basis of this feature paper. Inspired by studies on outdoor OA, this paper discusses and prioritizes issues related to indoor water-soluble OA and their effects on human health, providing a basis for future research in the field. The following three main topics are addressed: (1) what is known about the origin, mass contribution, and health effects of WSOM in outdoor air particles; (2) the current state-of-the-art on the WSOM in indoor air particles, the main challenges and opportunities for its chemical characterization and cytotoxicity evaluation; and (3) why the aerosol WSOM should be considered in future indoor air quality studies. While challenging, studies on the WSOM fraction in air particles are highly necessary to fully understand its origin, fate, toxicity, and long-term risks indoors.
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- 2021
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9. Determination of Formaldehyde Yields in E-Cigarette Aerosols: An Evaluation of the Efficiency of the DNPH Derivatization Method
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Xiaohong C. Jin, Regina M. Ballentine, William P. Gardner, Matt S. Melvin, Yezdi B. Pithawalla, Karl A. Wagner, Karen C. Avery, and Mehran Sharifi
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e-cigarette ,e-liquid ,aerosol ,2,4-DNPH derivatization ,formaldehyde ,“hidden formaldehyde” ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Recent reports have suggested that (1) formaldehyde levels (measured as a hydrazone derivative using the DNPH derivatization method) in Electronic Nicotine Delivery Systems (ENDS) products were underreported because formaldehyde may react with propylene glycol (PG) and glycerin (Gly) in the aerosol to form hemiacetals; (2) the equilibrium would shift from the hemiacetals to the acetals in the acidic DNPH trapping solution. In both cases, neither the hemiacetal nor the acetal would react with DNPH to form the target formaldehyde hydrazone, due to the lack of the carbonyl functional group, thus underreporting formaldehyde. These reports were studied in our laboratory. Our results showed that the aerosol generated from formaldehyde-fortified e-liquids provided a near-quantitative recovery of formaldehyde in the aerosol, suggesting that if any hemiacetal was formed in the aerosol, it would readily hydrolyze to free formaldehyde and, consequently, form formaldehyde hydrazone in the acidic DNPH trapping solution. We demonstrated that custom-synthesized Gly and PG hemiacetal adducts added to the DNPH trapping solution would readily hydrolyze to form the formaldehyde hydrazone. We demonstrated that acetals of PG and Gly present in e-liquid are almost completely transferred to the aerosol during aerosolization. The study results demonstrate that the DNPH derivatization method allows for an accurate measurement of formaldehyde in vapor products.
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- 2021
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10. Multidimensional Analytical Characterization of Water-Soluble Organic Aerosols: Challenges and New Perspectives
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Regina M. B. O. Duarte, João T. V. Matos, and Armando C. Duarte
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organic aerosols ,air particles ,water-soluble organic matter ,2D NMR spectroscopy ,high-resolution mass spectrometry ,EEM fluorescence spectroscopy ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
Water-soluble organic aerosols (OA) are an important component of air particles and one of the key drivers that impact both climate and human health. Understanding the processes involving water-soluble OA depends on how well the chemical composition of this aerosol component is decoded. Yet, obtaining detailed information faces several challenges, including water-soluble OA collection, extraction, and chemical complexity. This review highlights the multidimensional non-targeted analytical strategies that have been developed and employed for providing new insights into the structural and molecular features of water-soluble organic components present in air particles. First, the most prominent high-resolution mass spectrometric methods for near real-time measurements of water-soluble OA and their limitations are discussed. Afterward, a special emphasis is given to the degree of compositional information provided by offline multidimensional analytical techniques, namely excitation–emission (EEM) fluorescence spectroscopy, high-resolution mass spectrometry and two-dimensional nuclear magnetic resonance (NMR) spectroscopy and their hyphenation with chromatographic systems. The major challenges ahead on the application of these multidimensional analytical strategies for OA research are also addressed so that they can be used advantageously in future studies.
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- 2021
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11. Structural and Optical Properties of Self-Catalyzed Axially Heterostructured GaPN/GaP Nanowires Embedded into a Flexible Silicone Membrane
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Olga Yu. Koval, Vladimir V. Fedorov, Alexey D. Bolshakov, Sergey V. Fedina, Fedor M. Kochetkov, Vladimir Neplokh, Georgiy A. Sapunov, Liliia N. Dvoretckaia, Demid A. Kirilenko, Igor V. Shtrom, Regina M. Islamova, George E. Cirlin, Maria Tchernycheva, Alexey Yu. Serov, and Ivan S. Mukhin
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flexible optoelectronics ,self-catalyzed ,dilute nitrides ,GaPN ,GaP ,nanowire ,Chemistry ,QD1-999 - Abstract
Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and structural properties were examined by means of Raman microspectroscopy and transmission electron microscopy. To study the optical properties of the synthesized nanoheterostructures, the nanowire array was embedded into the silicone rubber membrane and further released from the growth substrate. The reported approach allows us to study the nanowire optical properties avoiding the response from the parasitically grown island layer. Photoluminescence and Raman studies reveal different nitrogen content in nanowires and parasitic island layer. The effect is discussed in terms of the difference in vapor solid and vapor liquid solid growth mechanisms. Photoluminescence studies at low temperature (5K) demonstrate the transition to the quasi-direct gap in the nanowires typical for diluted nitrides with low N-content. The bright room temperature photoluminescent response demonstrates the potential application of nanowire/polymer matrix in flexible optoelectronic devices.
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- 2020
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12. Facile Synthesis of 'Boron-Doped' Carbon Dots and Their Application in Visible-Light-Driven Photocatalytic Degradation of Organic Dyes
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Zhili Peng, Yiqun Zhou, Chunyu Ji, Joel Pardo, Keenan J. Mintz, Raja R. Pandey, Charles C. Chusuei, Regina M. Graham, Guiyang Yan, and Roger M. Leblanc
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carbon dots ,photo catalysis ,dye degradation ,environment clean ,rhodamine B ,methylene blue ,Chemistry ,QD1-999 - Abstract
Carbon dots (C-dots) were facilely fabricated via a hydrothermal method and fully characterized. Our study shows that the as-synthesized C-dots are nontoxic, negatively charged spherical particles (average diameter 4.7 nm) with excellent water dispersion ability. Furthermore, the C-dots have a rich presence of surface functionalities such as hydroxyls and carboxyls as well as amines. The significance of the C-dots as highly efficient photocatalysts for rhodamine B (RhB) and methylene blue (MB) degradation was explored. The C-dots demonstrate excellent photocatalytic activity, achieving 100% of RhB and MB degradation within 170 min. The degradation rate constants for RhB and MB were 1.8 × 10−2 and 2.4 × 10−2 min−1, respectively. The photocatalytic degradation performances of the C-dots are comparable to those metal-based photocatalysts and generally better than previously reported C-dots photocatalysts. Collectively considering the excellent photocatalytic activity toward organic dye degradation, as well as the fact that they are facilely synthesized with no need of further doping, compositing, and tedious purification and separation, the C-dots fabricated in this work are demonstrated to be a promising alternative for pollutant degradation and environment protection.
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- 2020
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13. COMPARAÇÃO DE PROCESSAMENTOS MATEMÁTICOS DE DADOS VOLTAMÉTRICOS: APLICAÇÃO NA DETERMINAÇÃO SIMULTÂNEA DE FLUOROQUINOLONAS
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Luiz H. de Oliveira, Lauro A. Pradela, André L. Santos, Regina M. Takeuchi, and Magno A. G. Trindade
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fluoroquinolones ,deconvolution ,derivative ,micellar medium ,electroanalysis ,Chemistry ,QD1-999 - Abstract
This paper describes a comparative study between the procedures of deconvolution and the second-order derivative of square wave voltammograms to achieve separation of the voltammetric peaks of levofloxacin (LEVO) and norfloxacin (NOR), for their simultaneous quantification in urine samples. The obtained results indicate that the use of second-derivative voltammograms coupled with carbon screen-printed electrodes is the most efficient approach for completely separating the voltammetric peaks of LEVO and NOR. In addition, this approach has produced detection limits lower than 1.0 µmol L-1 and a wide linear range for both drugs. The proposed method was successfully used to simultaneously determine LEVO and NOR in spiked human and bovine urine samples with recovery percentages close to 100% for all analyzed samples.
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- 2015
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14. Determinação Voltamétrica de Nitrito Empregando o Íon [Fe(CN)6]3- como Mediador Eletroquímico
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Lauro A. Pradela Filho, Regina M. Takeuchi, Magno A. G. Trindade, and André L. Santos
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carbon paste electrode ,nitrite ,potassium ferricyanide ,cyclic voltammetry ,Science ,Chemistry ,QD1-999 - Abstract
In this work, a voltammetric method for determination of nitrite in tap and mineral waters samples was developed. The method is based on the reduction of nitrite catalyzed by the electrochemical mediator [Fe(CN)6]3-. A carbon paste electrode (CPE) prepared with solid paraffin as binder agent was used as working electrode and cyclic voltammetry was the voltammetric technique employed for nitrite quantification. All parameters of the analytical method were optimized and the best conditions obtained were: BR buffer 0.04 mol L-1 pH = 1.0 as supporting electrolyte and 0.7 mmol L-1 of Fe(CN)6] 3- in the electrochemical cell. Under these optimized conditions, the method presented a linear range from 0.05 to 2.5 mmol L-1 of nitrite, with limits of detection and quantification equal to 22 and 75 μmol L-1, respectively. Spiked samples of mineral and tap water were analyzed by the proposed method and recovery percentages close to 100 % were obtained for all analyzed samples. Moreover, the method has presented a satisfactory precision since low values of relative standard deviation (RSD) were always obtained. These results indicate that the method allow the reliable determination of nitrite in water samples in a simple and inexpensive way. DOI: http://dx.doi.org/10.17807/orbital.v7i1.679
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- 2015
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15. Determinação de Chumbo em Águas de Abastecimento Utilizando Filmes de Bismuto Crescidos in situ Sobre Eletrodos de Pasta de Carbono
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Sarah P. Monteiro, Leandro A. R. Ribeiro, Wilson T. Fonseca, Regina M. Takeuchi, and André L. Santos
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carbon paste electrodes ,bismuth film ,lead ,anodic stripping voltammetry ,tap water ,Science ,Chemistry ,QD1-999 - Abstract
In this work, bismuth films were electrodeposited in situ onto carbon paste electrodes (CPEs) and they were used for lead determination in tap water samples by anodic stripping square wave voltammetry. The analytical performance of CPEs prepared with different binder agents was compared. It was observed that CPEs prepared with solid paraffin as binder agent provided the best results. All parameters of the analytical method were optimized and the best conditions obtained were: acetate buffer 0.1 mol L-1 (pH=4.75) as supporting electrolyte; pre-concentration time of 240 s and electrodepositing potential of -1.2 V vs. Ag/AgCl/KClsat. The best Bi3+ concentration was 2.0 μmol L-1. At these optimized conditions, analytical curves were constructed and two linear regions were obtained: 25 to 100 nmol L-1 and 250 to 1000 nmol L-1. Detection limits (LD) corresponding to these linear ranges were, respectively, 5.77 and 52.3 nmol L-1. Recovery experiments were performed in tap water samples and recovery percentages close to 100 % were always obtained although the best results were obtained for samples spiked with 250 nmol L-1 of Pb2+.
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- 2014
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16. Desenvolvimento de um sistema de análise por injeção em fluxo utilizando materiais alternativos de baixo custo para fins didáticos
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Bruna C. S. Moreira, Regina M. Takeuchi, Eduardo M. Richter, and André L. Santos
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amperometric detection ,didactic experiments ,flow injection analysis ,Chemistry ,QD1-999 - Abstract
This work describes a simple and inexpensive flow injection analysis system in which gravity force provides fluid propulsion while needles for insulin administration or metallic wires act as electrodes for amperometric detection. The proposed system was able to demonstrate the influence of several operational parameters on the transient signals. Moreover, this system was successfully used to evaluate both the stoichiometry of Cu2+-EDTA complex and the effect of pH on the kinetics of the reaction between ferricyanide and ascorbic acid. Therefore, the proposed system can be regarded as an efficient and accessible didactic tool for the teaching of FIA principles.
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- 2014
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17. Avaliação da eficiência de uma célula a combustível estacionária de ácido fosfórico Efficiency evaluation for stationary phosphoric acid fuel cell
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Rafael H. Camparin, Luiz A. C. Meleiro, Regina M. M. Jorge, Mauricio P. Cantão, and Patricio R. Impinnisi
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fuel cell ,balance of plant ,efficiency ,Chemistry ,QD1-999 - Abstract
Operation and performance of a commercial PAFC power plant were analyzed. Processes influencing energy conversion efficiency were studied in each module of the fuel cell power plant. The main processes were simulated using mass and energy balance equations, and the results were validated by means of experimental data. It was concluded that the electrical efficiency is higher in comparison with microturbines. The main result achieved is a better understanding of balance of plant processes, knowledge necessary for fuel cell power plant development.
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- 2007
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18. A Reliable Homemade Electrode Based on Glassy Polymeric Carbon
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Santos, Andre L., Takeuchi, Regina M., and Oliviero, Herilton P.
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The production of a GPC-based material by submitting a cross-linked resin precursor to control thermal conditions is discussed. The precursor material is prepolymerized at 60-degree Celsius in a mold and is carbonized in inert atmosphere by slowly raising the temperature, the rise is performed to avoid change in the shape of the carbonization (1,2,5).
- Published
- 2004
19. Flexible Perovskite CsPbBr3 Light Emitting Devices Integrated with GaP Nanowire Arrays in Highly Transparent and Durable Functionalized Silicones
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Vladimir Neplokh, Regina M. Islamova, Olga Yu. Koval, Ivan Mukhin, Vlad A. Sharov, Fedor M. Kochetkov, Sergey V. Makarov, Konstantin V. Deriabin, Vladimir V. Fedorov, Dmitry Gets, Anna S. Miroshnichenko, Dmitry V. Krasnikov, Nikita A. Filatov, Vadim Yu. Kukushkin, Albert G. Nasibulin, Alexey M. Mozharov, and Maria Baeva
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Fabrication ,Materials science ,Nanowire ,Nanotechnology ,Carbon nanotube ,Silicone rubber ,law.invention ,chemistry.chemical_compound ,Silicone ,chemistry ,law ,General Materials Science ,Electronics ,Physical and Theoretical Chemistry ,Perovskite (structure) ,Light-emitting diode - Abstract
The architecture of transparent contacts is of utmost importance for creation of efficient flexible light-emitting devices (LEDs) and other deformable electronic devices. We successfully combined the newly synthesized transparent and durable silicone rubbers and the semiconductor materials with original fabrication methods to design LEDs and demonstrate their significant flexibility. We developed electrodes based on a composite GaP nanowire-phenylethyl-functionalized silicone rubber membrane, improved with single-walled carbon nanotube films for a hybrid poly(ethylene oxide)-metal-halide perovskite (CsPbBr3) flexible green LED. The proposed approach provides a novel platform for fabrication of flexible hybrid optoelectronic devices.
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- 2021
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20. Environmental exposure and clinical correlates of hepatocellular carcinoma in New York City: a case only study
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Abby B. Siegel, Regina M. Santella, Jing Shen, and Hui-Chen Wu
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Cancer Research ,medicine.medical_specialty ,Aflatoxin ,Aflatoxin B1 ,Carcinoma, Hepatocellular ,Bilirubin ,Gastroenterology ,Article ,chemistry.chemical_compound ,Internal medicine ,Diabetes mellitus ,medicine ,Humans ,Hematology ,Adiponectin ,business.industry ,Liver Neoplasms ,Environmental Exposure ,Environmental exposure ,medicine.disease ,Oncology ,chemistry ,Hepatocellular carcinoma ,Biomarker (medicine) ,New York City ,business - Abstract
In the U.S., Hepatocellular carcinoma (HCC) incidence rates have increased. We aimed to determine whether environmental exposure plays a role in the high incidence of HCC observed in New York City. We conducted a hospital-based case only study to examine the prevalence of aflatoxin B1 (AFB1)- and polycyclic aromatic hydrocarbon (PAH)-albumin adducts and the distribution of adducts by different characteristics of HCC patients. Blood samples were collected from 155 HCC patients for biomarker analyses. We observed that about 46% and 49% of cases had detectable AFB1- and PAH-albumin adducts, respectively. There were significant differences between AFB1-albumin adducts and selected factors such as HCV infection status (p = 0.04), diabetes (p = 0.03) and Barcelona Clinic Liver Cancer (BCLC) stage (p = 0.02). Cases with detectable PAH-albumin adducts had a smoking history compared with those with nondetectable levels (p = 0.04). The level of AFB1-albumin adducts was positively correlated with plasma bilirubin (rs=0.32, p s=0.28, p = 0.0005). The level of aflatoxin B1-albumin adducts was negatively associated with blood albumin concentration (rs=-0.28, p = 0.0009) and plasma DNA LINE-1 methylation (rs=-0.16, p = 0.04). Our study provides additional evidence that environmental exposures including to aflatoxin might partially explain the increase in the incidence of HCC in the US.
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- 2021
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21. Structural Features of Polymer Ligand Environments Dramatically Affect the Mechanical and Room-Temperature Self-Healing Properties of Cobalt(II)-Incorporating Polysiloxanes
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Konstantin V. Deriabin, Vadim Yu. Kukushkin, Alexander S. Novikov, Mariya A. Kryukova, Nina A. Ignatova, Sergey O. Kirichenko, and Regina M. Islamova
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Inorganic Chemistry ,chemistry.chemical_classification ,chemistry ,Chemical engineering ,Ligand ,Self-healing ,Organic Chemistry ,chemistry.chemical_element ,Polymer ,Physical and Theoretical Chemistry ,Affect (psychology) ,Cobalt - Published
- 2021
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22. <scp>Low‐cost</scp> conductive films based on graphite and cellulose acetate as promising electroanalytical platforms
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Elaine Kikuti, Marcos V. Ferreira, Lauro A. Pradela Filho, Rosana Maria Nascimento de Assunção, Thaís G. Souza, Regina M. Takeuchi, and Guilherme Augusto Paixão
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chemistry.chemical_compound ,Materials science ,Polymers and Plastics ,chemistry ,Chemical engineering ,Hydroquinone ,Graphite ,Cellulose acetate ,Electrical conductor - Published
- 2021
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23. Assessment of active areas for the oxygen evolution reaction on an amorphous iridium oxide surface
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Regina M. Kluge, Aliaksandr S. Bandarenka, and Richard W. Haid
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Hydrogen ,010405 organic chemistry ,Oxygen evolution ,Oxide ,chemistry.chemical_element ,Electrolyte ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Amorphous solid ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Iridium ,Physical and Theoretical Chemistry - Abstract
Electrocatalytic “green” production of hydrogen from water for sustainable energy provision schemes is currently inefficient due to the sluggish kinetics of the oxygen evolution reaction (OER) at the anodes of the electrolysers. In the case of acidic polymer electrolyte membrane electrolysers, iridium (Ir) oxide catalysts pose a promising compromise between good OER activity and stability. However, the structure–activity relations for these materials remain largely unknown because the surface of a “real” oxide catalyst under reaction conditions becomes amorphous. In order to contribute to the understanding of these systems, we use electrochemical scanning tunnelling microscopy under reaction conditions (‘noise’ or n-EC-STM). With this technique, active areas can be detected by an increased noise level of the STM signal compared to inactive sites. The n-EC-STM measurements are applied to an amorphous iridium oxide surface, which is formed during electrochemical cycling of Ir(1 1 1). By doing so, we can monitor OER activity in-situ while simultaneously assessing the surface morphology. In order to elucidate the active areas, step and terrace sites were quantitatively compared to each other. The measurements reveal that terraces, step sites and concavities lead to a similar noise level increase in the STM signal. We, thus, conclude that the OER on the amorphous extended iridium oxide surface shows little structure-sensitivity. Subsequently, we suggest that in contrast to, e.g., metallic Pt for the oxygen electro-reduction, the shape of amorphous IrOx nanoparticles in an acidic medium should not significantly influence the OER turnover frequency.
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- 2021
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24. The effect of a high-selenium lentil diet on cardiovascular risk markers in an arsenic-exposed population
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Evana Akhtar, Grace P. S. Kwong, Rubhana Raqib, Judit E. G. Smits, and Regina M. Krohn
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inorganic chemicals ,education.field_of_study ,Nutrition and Dietetics ,Exposed Population ,business.industry ,Population ,Medicine (miscellaneous) ,chemistry.chemical_element ,Physiology ,Excretion ,Blood pressure ,chemistry ,Plasma lipids ,Medicine ,education ,business ,ARSENIC EXPOSURE ,Selenium ,Arsenic - Abstract
Chronic arsenic exposure is associated with a number of systemic diseases, including cardiovascular disease. Selenium has been shown to promote arsenic excretion from the body. We investigated if a high-selenium lentil diet has an effect on blood pressure and plasma lipid levels in an arsenic-exposed population by conducting a 6-month randomized controlled dietary intervention trial with 405 participants.
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- 2021
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25. Cyclometalated Platinum(II) Complexes Simultaneously Catalyze the Cross-Linking of Polysiloxanes and Function as Luminophores
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Mikhail A. Kinzhalov, Regina M. Islamova, Andrey S. Smirnov, Vadim Yu. Kukushkin, Elina V. Sokolova, Galina L. Starova, and Mikhail V. Dobrynin
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chemistry.chemical_compound ,Polymers and Plastics ,chemistry ,Hydrosilylation ,Process Chemistry and Technology ,Organic Chemistry ,Polymer chemistry ,chemistry.chemical_element ,Platinum ,Catalysis - Abstract
A family of the C,N-cyclometalated species [Pt(ppy)Cl(PPh3)], [Pt(ppy)Cl(CNCy)], [Pt(ppy)(CNCy)(PPh3)](OTf), and [Pt(ppy)(CNCy)2](BF4) (ppy = 2-phenylpyridinato-C2,N; Cy = cyclohexyl) was generated...
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- 2021
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26. pH and redox triggered doxorubicin release from covalently linked carbon dots conjugates
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Sajini D. Hettiarachchi, Heidi Maklouf, Regina M. Graham, Steven Vanni, Roger M. Leblanc, Emel Kirbas Cilingir, Elif S. Seven, and Suraj Paudyal
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macromolecular substances ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,Redox ,Dithiothreitol ,chemistry.chemical_compound ,Drug Delivery Systems ,Cell Line, Tumor ,polycyclic compounds ,medicine ,General Materials Science ,Inducer ,Doxorubicin ,Viability assay ,Antibiotics, Antineoplastic ,Chemistry ,organic chemicals ,technology, industry, and agriculture ,Hydrogen-Ion Concentration ,021001 nanoscience & nanotechnology ,Carbon ,0104 chemical sciences ,carbohydrates (lipids) ,Drug Liberation ,Cell culture ,Drug delivery ,Biophysics ,0210 nano-technology ,Oxidation-Reduction ,medicine.drug ,Conjugate - Abstract
Tumor microenvironment responsive drug delivery systems are potential approaches to reduce the acute toxicity caused by high-dose cancer chemotherapy. Notwithstanding the conventional nano-drug delivery systems, the redox and pH stimuli drug delivery systems are currently gaining attention. Therefore, the current study was designed to compare three different covalent carbon dots (C-dots) systems based on doxorubicin (dox) release profiles and cancer cell viability efficacy under acidic and physiological conditions. The C-dots nanosystems that were examined in this study are directly conjugated (C-dots-dox), pH triggered (C-dots-HBA-dox), and the redox stimuli (C-dots-S-S-dox) conjugates. The drug loading content (DLC%) of the C-dots-S-S-dox, C-dots-HBA-dox, and C-dots-dox was 34.2 ± 0.4, 60.0 ± 0.3, and 70.0 ± 0.2%, respectively, that examined by UV-vis spectral analysis. The dox release paradigms were emphasized that all three conjugates were promisingly released the dox from C-dots faster in acidic pH than in physiological pH. The displayed highest dox released percentage in the acidic medium was 74.6 ± 0.8% obtained by the pH stimuli, C-dots-HBA-dox conjugate. When introducing the redox inducer, dithiothreitol (DTT), preferentially, the redox stimuli C-dot-S-S-dox conjugate demonstrated a faster dox release at acidic pH than in the pH 7.4. The SJGBM2 cell viability experiments revealed that the pH stimuli, C-dots-HBA-dox conjugate, displayed a significant cell viability drop in the artificially acidified pH 6.4 medium. However, in the physiological pH, the redox stimuli, C-dots-S-S-dox conjugate, was promising over the pH stimuli C-dots-HBA-dox, exhibiting cell viability of 60%, though its' efficacy dropped slightly in the artificially acidified pH 6.4 medium. Moreover, the current study illustrates the stimuli conjugates' remarkable efficacy on sustain drug release than direct amide linkage.
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- 2021
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27. Non-enzymatic lactose molecularly imprinted sensor based on disposable graphite paper electrode
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Edervaldo Buffon, Regina M. Takeuchi, Lauro A. Pradela-Filho, Diele A.G. Araújo, Maísa Azevedo Beluomini, José Luiz da Silva, André L. Santos, Nelson Ramos Stradiotto, Universidade Estadual Paulista (Unesp), and Universidade Federal de Uberlândia (UFU)
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Lactose sensing ,Central composite design ,Polymers ,Lactose ,02 engineering and technology ,Non-enzymatic electroanalysis ,Electrosynthesis ,Polypyrrole ,01 natural sciences ,Biochemistry ,Analytical Chemistry ,Molecular Imprinting ,chemistry.chemical_compound ,Molecular recognition ,Limit of Detection ,Paper-based electrode ,Animals ,Humans ,Environmental Chemistry ,Pyrroles ,Electrodes ,Spectroscopy ,Detection limit ,Chromatography ,010401 analytical chemistry ,Molecularly imprinted polymer ,Electropolymerization ,Reproducibility of Results ,Electrochemical Techniques ,021001 nanoscience & nanotechnology ,Experimental design ,0104 chemical sciences ,chemistry ,Molecularly imprinted polymers ,Graphite ,0210 nano-technology ,Selectivity - Abstract
Made available in DSpace on 2021-06-25T10:45:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-25 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) Lactose (LAC) is a disaccharide - major sugar, present in milk and dairy products. LAC content is an important indicator of milk quality and abnormalities in food industries, as well as in human and animal health. The present study reports the development of an innovative imprinted voltammetric sensor for sensitive detection of LAC. The sensor was constructed using electropolymerized pyrrole (Py) molecularly imprinted polymer (MIP) on graphite paper electrode (PE). The MIP film was constructed through the electrosynthesis of polypyrrole (PPy) in the presence of LAC (template molecule) on PE (PPy/PE). To optimize the detection conditions, several factors affecting the PPy/PE sensor performance were assessed by multivariate methods (Plackett–Burman design and central composite design). Under optimized conditions, the proposed analytical method was applied for LAC detection in whole and LAC-free milks, where it demonstrated high sensitivity and selectivity, with two dynamic linear ranges of concentration (1.0–10 nmol L−1 and 25–125 nmol L−1) and a detection limit of 0.88 nmol L−1. The MIP sensor showed selective molecular recognition for LAC in the presence of structurally related molecules. The proposed PPy/PE sensor exhibited good stability, as well as excellent reproducibility and repeatability. Based on the results obtained, the PPy/PE is found to be highly promising for sensitive detection of LAC. Analytical Chemistry Department Institute of Chemistry São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Institute of Exact and Natural Sciences of Pontal Federal University of Uberlandia, 1600 20 St., Ituiutaba, Minas Gerais State Bioenergy Research Institute (IPBEN) São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Analytical Chemistry Department Institute of Chemistry São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State Bioenergy Research Institute (IPBEN) São Paulo State University (UNESP), 55 Prof. Francisco Degni St., São Paulo State FAPESP: 2017/25329–6 FAPESP: 2018/12131–6 FAPESP: 2019/13818–8 CNPq: 408783/2018–4 CNPq: 443315/2014–0 CNPq: 447668/2014–5 CAPES: 88887.368610/2019–00 FAPEMIG: APQ-02078-15 FAPEMIG: APQ-02905-15
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- 2021
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28. A clinical mimicker of melanoma with distinctive histopathology: Topical silver nitrate exposure
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Regina M. Ondrasik, Aravindhan Sriharan, and Parisa Jordan
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Change over time ,medicine.medical_specialty ,Pathology ,Histology ,SILVER NITRATE EXPOSURE ,business.industry ,Melanoma ,Clinical appearance ,Dermatology ,medicine.disease ,Pathology and Forensic Medicine ,030207 dermatology & venereal diseases ,03 medical and health sciences ,Silver nitrate ,chemistry.chemical_compound ,0302 clinical medicine ,chemistry ,030220 oncology & carcinogenesis ,medicine ,Argyria ,Histopathology ,Corneal layer ,business - Abstract
Exposure to silver-containing compounds can result in reversible discoloration of the skin, presenting as an irregular brown or black macule, which can have a clinical appearance similar to melanoma. Both the clinical scenario and the histopathology are unique. Silver nitrate darkens with exposure to light, and the area can appear to change over time. On microscopic examination, there are coarse pigmented granules dispersed throughout the corneal layer, and largely absent from the remainder of the epidermis-although the precise location may depend on the duration of topical exposure. While argyria, its irreversible counterpart, has been well-characterized, only a single source has previously reported the histopathology of transient topical silver nitrate exposure. We present two cases, review the clinical and histopathologic differentials, and detail the distinctive histopathology that enables a diagnosis to be suggested in this clinical mimicker of melanoma.
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- 2020
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29. Formation of Diacetyl and Other α‑Dicarbonyl Compounds during the Generation of E‑Vapor Product Aerosols
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Donna C. Smith, Regina M. Ballentine, Karl A. Wagner, Georgios D. Karles, William P. Gardner, Yezdi B. Pithawalla, Karen C. Avery, Matt S. Melvin, Jason W. Flora, and Kimberly D Ehman
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General Chemical Engineering ,Hydroxyacetone ,Methylglyoxal ,Formaldehyde ,General Chemistry ,Diacetyl ,Article ,chemistry.chemical_compound ,Chemistry ,chemistry ,Organic chemistry ,Glyoxal ,Aldol condensation ,Retrosynthetic analysis ,QD1-999 ,Flavor - Abstract
Exposure to diacetyl (DA) has been linked to the respiratory condition bronchiolitis obliterans. Previous research has demonstrated that DA and other α-dicarbonyl compounds can be detected in both the e-liquids and aerosols of e-vapor products (EVPs). While some EVP manufacturers may add these compounds as flavor ingredients, the primary objective of this work was to determine the potential for the formation of α-dicarbonyl compounds during the generation of aerosols from EVPs where no DA or other α-dicarbonyl compounds are added to the e-liquid. A novel ultraperformance liquid chromatography-mass spectrometry-based analytical method for the determination of DA, acetyl propionyl, glyoxal, and methylglyoxal was developed and validated. Next, eight commercially available cig-a-like-type EVPs were evaluated for α-dicarbonyl formation. Increased levels of α-dicarbonyls were observed in the aerosols of all evaluated EVPs compared to their respective e-liquids. Mechanistic studies were conducted using a model microwave reaction system to identify key reaction precursors for DA generated from propylene glycol (PG) and carbon-13-labeled glycerin (GLY). These studies, along with the corresponding retrosynthetic analysis, resulted in the proposed formation pathway where hydroxyacetone is generated from PG and/or GLY. Hydroxyacetone then participates in an aldol condensation with formaldehyde where formaldehyde can also be generated from PG and/or GLY; the resultant product then dehydrates to form DA. This proposed pathway was further investigated through in situ synthetic organic experiments within the model microwave reaction system. This work establishes that DA is formed in the aerosol generation process of the EVPs tested though at levels below toxicological concern.
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- 2020
30. Aktivitätssteigerung der Wasserstoffentwicklung von Platinelektroden in alkalischen Medien unter Verwendung von Ni‐Fe‐Clustern
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Sebastian Watzele, Song Xue, Regina M. Kluge, Shujin Hou, Johannes Fichtner, Batyr Garlyyev, Aliaksandr S. Bandarenka, Xing Ding, and Richard W. Haid
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Chemistry ,General Medicine - Published
- 2020
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31. Iron Deposition and Ferroptosis in the Spleen in a Murine Model of Acute Radiation Syndrome
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William B. Rittase, Milan Rusnak, Grace V. Brehm, Jeannie M. Muir, Sang-Ho Lee, John E. Slaven, Regina M. Day, and Aviva J. Symes
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Pathology ,medicine.medical_specialty ,medicine.anatomical_structure ,Murine model ,Chemistry ,Ferroptosis ,Iron deposition ,medicine ,Acute Radiation Syndrome ,Spleen - Abstract
Total body radiation (TBI) can result in death associated with hematopoietic insufficiency. Although radiation causes apoptosis of white blood cells, red blood cells (RBC) undergo hemolysis due to hemoglobin denaturation. RBC lysis post-irradiation results in the release of iron into the plasma, producing a secondary toxic event. We investigated the impact of radiation-induced iron release on the spleen of mice following TBI and the effects of the radiation mitigator captopril. RBC and hematocrit were reduced ~7 days (nadir ~14 days) post-TBI. Prussian blue staining revealed ~20-60-fold increased Fe3+ in the spleen 7-14 days post-irradiation, also associated with altered expression of iron binding and transport proteins, determined by qPCR, western blotting, and immunohistochemistry. Captopril did not prevent iron deposition in the spleen, and did not significantly modulate most iron-binding proteins. Spleen volumes were markedly decreased 7-14 days, correlating with high Fe3+. At these time points, caspase-3 was activated and we identified four markers of ferroptosis, iron-dependent programmed cell death. Interestingly, p21/Waf1, a marker of accelerated senescence, was not upregulated in vivo. Macrophage inflammation is an important effect of TBI. We investigated the effects of radiation and Fe3+ on the cultured J774A.1 murine macrophage cell line. Radiation induced p21/Waf1 and ferritin, but not caspase-3, within 24 h. Radiation ± iron upregulated several markers of pro-inflammatory M1 polarization; radiation with iron also upregulated a marker of anti-inflammatory M2 polarization. Our data indicate that following TBI, iron accumulates in the spleen where it regulates iron binding proteins and triggers ferroptosis.
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- 2021
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32. Acetate Facilitated Nickel Catalyzed Coupling of Aryl Chlorides and Alkyl Thiols
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Ivana Fleischer, Regina M. Oechsner, and J. Philipp Wagner
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chemistry.chemical_classification ,Aryl ,chemistry.chemical_element ,General Chemistry ,Combinatorial chemistry ,Oxidative addition ,Catalysis ,chemistry.chemical_compound ,Nickel ,Deprotonation ,Thioether ,chemistry ,Catalytic cycle ,Alkyl - Abstract
We report a mild, fast and convenient catalytic system for the coupling of aryl chlorides with primary, secondary, as well as previously challenging tertiary alkyl thiols using an air-stable nickel(II) precatayst in combination with the low-cost base potassium acetate at room temperature. This new catalytic system tolerates a variety of functional groups and enables the generation of thioethers for a wide range of substrates, including pharmaceutical compounds in excellent yields. Chemoselec-tive functionalization of disubstituted substrates was demonstrated. Kinetic and NMR-studies, as well as DFT computations support a Ni(0)/Ni(II) catalytic cycle and identify the oxidative addition product as the resting state. Acetate coordination and subsequent acetate facilitated formation of a thiolate complex via internal deprotonation play a key role in the catalytic cycle.
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- 2021
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33. Deprotonated diaminocarbene platinum complexes for thermoresponsive luminescent silicone materials: both catalysts and luminophores
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Vadim P. Boyarskiy, Nikita S. Antonov, Alexander S. Mikherdov, Sergey V. Baykov, Mikhail V. Dobrynin, Regina M. Islamova, Polina Y. Savko, and Svetlana O. Kasatkina
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Inorganic Chemistry ,Coupling (electronics) ,chemistry.chemical_compound ,Deprotonation ,Silicone ,Materials science ,chemistry ,Hydrosilylation ,Polymer chemistry ,chemistry.chemical_element ,Platinum ,Luminescence ,Catalysis - Abstract
C,N-Chelate deprotonated diaminocarbene platinum(II) complexes were synthesized by coupling coordinated isocyanides and azinyl-substituted ureas. The complexes act as catalysts of α,ω-divinylpolydimethylsiloxane and poly(dimethylsiloxane-co-methylhydrosiloxane) hydrosilylation cross-linking. Silicone rubbers obtained with (aminoisoquinoline)-containing complex 3d exhibit temperature-responsive luminescence. Their emission changes irreversibly when heated from 80–100 °C (green radiation) to 120 °C or more (blue radiation).
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- 2021
34. Red GaPAs/GaP Nanowire-Based Flexible Light-Emitting Diodes
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Tatiana Statsenko, Vladimir Neplokh, Vladimir V. Fedorov, Eduard Moiseev, Fedor M. Kochetkov, G. E. Cirlin, Konstantin Shugurov, Sofia M. Morozova, Alexey M. Mozharov, Regina M. Islamova, Dmitry V. Krasnikov, Nuño Amador-Mendez, Ivan Mukhin, Albert G. Nasibulin, Maria Tchernycheva, Peter the Great St. Petersburg Polytechnic University, Alferov University, Higher School of Economics, Université Paris-Saclay, St. Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO), Skolkovo Institute of Science and Technology, Department of Chemistry and Materials Science, St. Petersburg State University, Aalto-yliopisto, and Aalto University
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Materials science ,General Chemical Engineering ,Nanowire ,Substrate (electronics) ,Carbon nanotube ,Electroluminescence ,Article ,law.invention ,chemistry.chemical_compound ,law ,flexible LED ,molecular beam epitaxy ,General Materials Science ,single-walled carbon nanotubes ,QD1-999 ,Diode ,Polydimethylsiloxane ,business.industry ,Nanowires ,Flexible LED ,Single-walled carbon nanotubes ,Chemistry ,chemistry ,nanowires ,Optoelectronics ,business ,GaPAs ,Molecular beam epitaxy ,Light-emitting diode - Abstract
Funding Information: V.N. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. V.F. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60037) for the support of the MBE growth. V.N. and F.K. thank the support from the Russian Foundation for Basic Research (grant 20-32-90182) for electrical measurements. V.N., F.K., R.I. and I.M. thank the Russian Scientific Foundation (RSF project No. 20-19-00256) for chemical treatment of PDMS. V.N., V.F., A.M., F.K. and K.S. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. E.M. thanks the Basic Research Program at the National Research University Higher School of Economics (HSE University) in 2021 for optical measurements. N.A.-M. and M.T. thank ITN Marie Curie project INDEED (grant No. 722176) for GaPAs NW/PDMS membrane investigation. This work received financial support from Partenariats Hubert Curien Kolmogorov project No. 43784UJ and Indo French Centre for the Promotion of Advanced Research (CEFIPRA) Project No. 6008-1. A.G.N. acknowledges the Russian Scientific Foundation (RSF project No. 21-72-20050) for synthesis of SWCNTs. Funding Information: Funding: V.N. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60040) for PDMS/MW membrane fabrication and optical measurements. V.F. thanks the Russian Foundation for Basic Research (RFBR project No. 19-32-60037) for the support of the MBE growth. V.N. and F.K. thank the support from the Russian Foundation for Basic Research (grant 20-32-90182) for electrical measurements. V.N., F.K., R.I. and I.M. thank the Russian Scientific Foundation (RSF project No. 20-19-00256) for chemical treatment of PDMS. V.N., V.F., A.M., F.K. and K.S. thank the Ministry of Science and Higher Education of the Russian Federation (FSRM-2020-0005) for the general support. E.M. thanks the Basic Research Program at the National Research University HigherSchool of Economics (HSE University) in 2021 for optical measurements. N.A.-M. and M.T. thank ITN Marie Curie project INDEED (grant No. 722176) for GaPAs NW/PDMS membrane investigation. This work received financial support from Partenariats Hubert Curien Kolmogorov project No. 43784UJ and Indo French Centre for the Promotion of Advanced Research (CEFIPRA) Project No. 6008-1. A.G.N. acknowledges the Russian Scientific Foundation (RSF project No. 21-72-20050) for synthesis of SWCNTs. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. We demonstrate flexible red light-emitting diodes based on axial GaPAs/GaP heterostruc-tured nanowires embedded in polydimethylsiloxane membranes with transparent electrodes involv-ing single-walled carbon nanotubes. The GaPAs/GaP axial nanowire arrays were grown by molecular beam epitaxy, encapsulated into a polydimethylsiloxane film, and then released from the growth substrate. The fabricated free-standing membrane of light-emitting diodes with contacts of single-walled carbon nanotube films has the main electroluminescence line at 670 nm. Membrane-based light-emitting diodes (LEDs) were compared with GaPAs/GaP NW array LED devices processed directly on Si growth substrate revealing similar electroluminescence properties. Demonstrated membrane-based red LEDs are opening an avenue for flexible full color inorganic devices.
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- 2021
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35. An opposing role for prelimbic cortical projections to the nucleus accumbens core in incubation of craving for cocaine versus water
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Regina M. Carelli and Travis M. Moschak
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Male ,medicine.medical_specialty ,Infralimbic cortex ,Drug-Seeking Behavior ,Context (language use) ,Stimulation ,Craving ,Self Administration ,Optogenetics ,Nucleus accumbens ,Toxicology ,Article ,Nucleus Accumbens ,Rats, Sprague-Dawley ,Cocaine ,Internal medicine ,medicine ,Animals ,Pharmacology (medical) ,Rats, Long-Evans ,Long-term depression ,Incubation ,Pharmacology ,Chemistry ,Water ,Rats ,Psychiatry and Mental health ,Endocrinology ,medicine.anatomical_structure ,medicine.symptom ,Cues - Abstract
Background Both drug and natural reward-seeking have been shown to increase following an extended period of abstinence, a phenomenon termed ‘incubation of craving’. Although this phenomenon involves many brain regions, the projections from the prelimbic cortex (PrL) to the nucleus accumbens (NAc) core have been strongly implicated in incubation of cocaine-seeking. However, this circuit has not been investigated in the context of incubation of craving for natural rewards. Methods Male Long Evans rats were trained to self-administer cocaine or water/saline 6 h/d for 14 days and subsequently entered 1 month of experimenter-imposed abstinence. Rats then underwent an optogenetic stimulation protocol used to induce long term depression in the PrL terminals to the NAc core immediately before beginning an extinction test used to assess incubation of craving. Results Control cocaine rats showed heightened drug-seeking on day 30 when compared to day 1 of abstinence, demonstrating incubation of craving. Notably, optogenetic stimulation of the PrL to NAc core pathway blocked this behavior in cocaine rats. In contrast, optogenetic stimulation of the PrL to NAc core pathway induced incubation of craving in water/saline rats. Conclusions These findings suggest that neuroadaptations in the PrL to NAc core pathway play opposing roles in the incubation of craving for cocaine versus water.
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- 2021
36. Determination of Formaldehyde Yields in E-Cigarette Aerosols: An Evaluation of the Efficiency of the DNPH Derivatization Method
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Regina M. Ballentine, Karen C. Avery, Matt S. Melvin, William P. Gardner, Mehran Sharifi, Karl A. Wagner, Yezdi B. Pithawalla, and Xiaohong C. Jin
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chemistry.chemical_classification ,Chemistry ,aerosol ,e-liquid ,Physics ,QC1-999 ,Acetal ,Formaldehyde ,Hydrazone ,Filtration and Separation ,e-cigarette ,“hidden formaldehyde” ,Analytical Chemistry ,Adduct ,Hydrolysis ,chemistry.chemical_compound ,2,4-DNPH derivatization ,formaldehyde ,formaldehyde-containing hemiacetal/acetal adducts ,Organic chemistry ,Hemiacetal ,Derivatization ,QD1-999 ,Aerosolization - Abstract
Recent reports have suggested that (1) formaldehyde levels (measured as a hydrazone derivative using the DNPH derivatization method) in Electronic Nicotine Delivery Systems (ENDS) products were underreported because formaldehyde may react with propylene glycol (PG) and glycerin (Gly) in the aerosol to form hemiacetals; (2) the equilibrium would shift from the hemiacetals to the acetals in the acidic DNPH trapping solution. In both cases, neither the hemiacetal nor the acetal would react with DNPH to form the target formaldehyde hydrazone, due to the lack of the carbonyl functional group, thus underreporting formaldehyde. These reports were studied in our laboratory. Our results showed that the aerosol generated from formaldehyde-fortified e-liquids provided a near-quantitative recovery of formaldehyde in the aerosol, suggesting that if any hemiacetal was formed in the aerosol, it would readily hydrolyze to free formaldehyde and, consequently, form formaldehyde hydrazone in the acidic DNPH trapping solution. We demonstrated that custom-synthesized Gly and PG hemiacetal adducts added to the DNPH trapping solution would readily hydrolyze to form the formaldehyde hydrazone. We demonstrated that acetals of PG and Gly present in e-liquid are almost completely transferred to the aerosol during aerosolization. The study results demonstrate that the DNPH derivatization method allows for an accurate measurement of formaldehyde in vapor products.
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- 2021
37. The contribution of ketone bodies to glycolytic inhibition for the treatment of adult and pediatric glioblastoma
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Ziad Khatib, Frederic A. Vallejo, Winston M. Walters, Sumedh S. Shah, Jeffrey S. Prince, Ricardo J. Komotar, Regina M. Graham, Steven Vanni, and Nicolas de Cordoba
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Cancer Research ,Programmed cell death ,medicine.diagnostic_test ,Chemistry ,Mitochondrion ,03 medical and health sciences ,0302 clinical medicine ,Neurology ,Oncology ,Western blot ,Apoptosis ,030220 oncology & carcinogenesis ,Adjunctive treatment ,medicine ,Cancer research ,Ketone bodies ,Neurology (clinical) ,Viability assay ,OXCT1 ,030217 neurology & neurosurgery - Abstract
Glioblastoma (GBM) remains one of the most lethal primary brain tumors in children and adults. Targeting tumor metabolism has emerged as a promising-targeted therapeutic strategy for GBM and characteristically resistant GBM stem-like cells (GSCs). Gene expression data was obtained from the online patient-histology database, GlioVis. GSC mitochondria morphology was examined by TEM. Cell viability and effect on GSC self-renewal was determined via MTS assay and neurosphere assay, respectively. Proteins were evaluated by Western Blot. Enzymes necessary for ketone catabolism (BDH1, OXCT1 and ACAT1) are significantly downregulated in adult and pediatric GBM. GSC mitochondrial ultrastructure suggested defects in oxidative phosphorylation. Treatment of both GBM and GSC cell lines resulted in dose-dependent decreases in viability in response to glycolytic inhibitor 2-deoxy-D-glucose (2-DG), and ketone body Acetoacetate (AA), but not β-hydroxybutyrate (βHB). AA induced apoptosis was confirmed by western blot analysis, indicating robust caspase activation and PARP cleavage. AA reduced neurosphere formation at concentrations as low as 1 mM. Combined treatment of low dose 2-DG (50 μM) with AA resulted in more cell death than either treatment alone. The effect was greater than additive at low concentrations of AA, reducing viability approximately 50% at 1 mM AA. AA was found to directly upregulate mitochondrial uncoupling protein 2 (UCP2), which may explain this potential drug synergism via multi-faceted inhibition of the glycolytic pathway. Targeting the metabolic pathway of GBM via glycolytic inhibition in conjunction with ketogenic diet or exogenous ketone body supplementation warrants further investigation as a promising adjunctive treatment to conventional therapy.
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- 2020
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38. Modified silicone rubber for fabrication and contacting of flexible suspended membranes of n-/p-GaP nanowires with a single-walled carbon nanotube transparent contact
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Vladimir Mikhailovskii, Vladimir Neplokh, Konstantin V. Deriabin, Maria Tchernycheva, Daniil A. Ilatovskii, Albert G. Nasibulin, Regina M. Islamova, Fedor M. Kochetkov, G. E. Cirlin, Igor E. Eliseev, Ivan Mukhin, Dmitry V. Krasnikov, Vladimir V. Fedorov, Alexey D. Bolshakov, RAS - St. Petersburg Academic University, St. Petersburg State University, Skolkovo Institute of Science and Technology, Université Paris-Saclay, Aalto University, Department of Chemistry and Materials Science, and Aalto-yliopisto
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Materials science ,Fabrication ,Polymethylhydrosiloxane ,Nanowire ,Nanotechnology ,02 engineering and technology ,General Chemistry ,Carbon nanotube ,Substrate (electronics) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Silicone rubber ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Natural rubber ,law ,visual_art ,Electrode ,Materials Chemistry ,visual_art.visual_art_medium ,0210 nano-technology - Abstract
Rubber materials are the key components of flexible optoelectronic devices, especially for the light-emitting diodes based on arrays of inorganic nanowires (NWs). This paper reports on polydimethylsiloxane-graft-polystyrene (PDMS-St) as a new flexible substrate of GaP NW array structures. The NWs were encapsulated by the newly introduced G-coating method to substitute the inefficient mainstream spin-coating. To further exploit the flexibility and the stretchability of the NW/PDMS-St structures, the ferrocenyl-containing polymethylhydrosiloxane was synthesized and successfully used as an electrode for the NWs. In order to make an alternative highly efficient transparent electrode, a new application of conductive single-walled carbon nanotubes was demonstrated. The novel materials and methods demonstrated unsurpassed mechanical stability of the fabricated flexible electronic devices.
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- 2020
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39. Buriti Oil: Nutritional Quality Index and Antioxidant and Antidiabetic Effect
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Regina M. Mendes Oliveira, Efraim C. Pereira, Cáritas de J. S. Mendonça, and Fernanda T. Pereira
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Buriti oil ,Index (economics) ,Antioxidant ,biology ,Chemistry ,Mauritia flexuosa ,medicine.medical_treatment ,medicine ,General Chemistry ,Food science ,Nutritional quality ,biology.organism_classification - Published
- 2020
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40. Evaluation of Nanoparticle Tracking Analysis for the Detection of Rod-Shaped Particles and Protein Aggregates
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Brandon M. Hoover and Regina M. Murphy
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Amyloid ,Materials science ,Surface Properties ,Population ,Pharmaceutical Science ,Nanoparticle tracking analysis ,02 engineering and technology ,Myosins ,Protein aggregation ,030226 pharmacology & pharmacy ,Light scattering ,Protein Aggregates ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Animals ,Humans ,Nanotechnology ,Particle Size ,education ,education.field_of_study ,021001 nanoscience & nanotechnology ,Dynamic Light Scattering ,Monomer ,Immunoglobulin M ,Models, Chemical ,chemistry ,Chemical engineering ,Hydrodynamics ,alpha-Synuclein ,Nanoparticles ,Particle ,Nanorod ,Gold ,Rabbits ,Particle size ,0210 nano-technology ,Protein Binding - Abstract
Nanoparticle tracking analysis (NTA) is an important technique for measuring hydrodynamic size of globular biological particles including liposomes and viruses. Less attention has been paid to NTA of rod-like particles, despite their considerable interest. For example, amyloid fibrils and protofibrils are protein aggregates with rod-like morphology, diameters of 2-15 nm, and lengths from 50 nm to 1 μm, and linked to diseases including Alzheimer's and Parkinson's. We used NTA to measure the concentration and hydrodynamic size of gold nanorods (10 nm diameter, 35-250 nm length) and myosin (2 nm diameter, 160 nm length), as models of rod-like particles. Measured hydrodynamic diameters of gold nanorods were consistent with theoretical calculations, as long as particle concentration and solution conditions were controlled. Myosin monomers were invisible by NTA, but a small population of aggregates was detected. We combined NTA results with other light scattering data to gain insight into number and size distribution of protein solutions containing both monomer and aggregates. Finally, we demonstrated the utility of NTA and its limitations by characterizing aggregates of alpha-synuclein. Of note is the use of NTA to detect a change in morphology from compact to elongated by analyzing the ratio of hydrodynamic size to intensity.
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- 2020
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41. During infant maltreatment, stress targets hippocampus, but stress with mother present targets amygdala and social behavior
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Maya Opendak, Kevin Bui, Bruce S. McEwen, Regina M. Sullivan, Emma Sarro, Ashleigh Showler, Donald A. Wilson, and Charlis Raineki
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Multidisciplinary ,Brain development ,Neurogenesis ,Vulnerability ,Mothers ,Hippocampus ,Social environment ,Biological Sciences ,Hippocampal formation ,Amygdala ,Rats ,chemistry.chemical_compound ,medicine.anatomical_structure ,chemistry ,Stress, Physiological ,Corticosterone ,medicine ,Animals ,Female ,Social Behavior ,Psychology ,Neuroscience - Abstract
Infant maltreatment increases vulnerability to physical and mental disorders, yet specific mechanisms embedded within this complex infant experience that induce this vulnerability remain elusive. To define critical features of maltreatment-induced vulnerability, rat pups were reared from postnatal day 8 (PN8) with a maltreating mother, which produced amygdala and hippocampal deficits and decreased social behavior at PN13. Next, we deconstructed the maltreatment experience to reveal sufficient and necessary conditions to induce this phenotype. Social behavior and amygdala deficits (volume, neurogenesis, c-Fos, local field potential) required combined chronic high corticosterone and maternal presence (not maternal behavior). Hippocampal deficits were induced by chronic high corticosterone regardless of social context. Causation was shown by blocking corticosterone during maltreatment and suppressing amygdala activity during social behavior testing. These results highlight (1) that early life maltreatment initiates multiple pathways to pathology, each with distinct causal mechanisms and outcomes, and (2) the importance of social presence on brain development.
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- 2019
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42. Metabolic Consequences of Cobalamin Scarcity in the Diatom Thalassiosira pseudonana as Revealed Through Metabolomics
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Katherine R. Heal, Regina M. Lionheart, Anitra E. Ingalls, Laura T. Carlson, and Natalie A. Kellogg
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0301 basic medicine ,Metabolite ,Thalassiosira pseudonana ,Transsulfuration pathway ,Microbiology ,Cobalamin ,03 medical and health sciences ,chemistry.chemical_compound ,Metabolomics ,hemic and lymphatic diseases ,polycyclic compounds ,Diatoms ,Methionine ,integumentary system ,biology ,fungi ,Methylmalonyl-CoA mutase ,nutritional and metabolic diseases ,030108 mycology & parasitology ,biology.organism_classification ,Vitamin B 12 ,030104 developmental biology ,Diatom ,chemistry ,Biochemistry ,Metabolome - Abstract
Diatoms perform an estimated 20% of global photosynthesis, form the base of the marine food web, and sequester carbon into the deep ocean through the biological pump. In some areas of the ocean, diatom growth is limited by the micronutrient cobalamin (vitamin B12), yet the biochemical ramifications of cobalamin limitation are not well understood. In a laboratory setting, we grew the diatom Thalassiosira pseudonana under replete and low cobalamin conditions to elucidate changes in metabolite pools. Using metabolomics, we show that the diatom experienced a metabolic cascade under cobalamin limitation that affected the central methionine cycle, transsulfuration pathway, and composition of osmolyte pools. In T. pseudonana, 5'-methylthioadenosine decreased under low cobalamin conditions, suggesting a disruption in the diatom's polyamine biosynthesis. Furthermore, two acylcarnitines accumulated under low cobalamin, suggesting the limited use of an adenosylcobalamin-dependent enzyme, methylmalonyl CoA mutase. Overall, these changes in metabolite pools yield insight into the metabolic consequences of cobalamin limitation in diatoms and suggest that cobalamin availability may have consequences for microbial interactions that are based on metabolite production by phytoplankton.
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- 2019
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43. Mechanism and therapeutic window of a genistein nanosuspension to protect against hematopoietic-acute radiation syndrome
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Michael R. Landauer, Adam J. Harvey, Regina M. Day, and Michael D. Kaytor
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Male ,Agonist ,medicine.drug_class ,Health, Toxicology and Mutagenesis ,Estrogen receptor ,Genistein ,Radiation-Protective Agents ,Pharmacology ,Injections, Intramuscular ,Mice ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Suspensions ,Regular Paper ,medicine ,Animals ,Radiology, Nuclear Medicine and imaging ,Estrogen receptor beta ,030304 developmental biology ,0303 health sciences ,Radiation ,business.industry ,Lethal dose ,Dose-Response Relationship, Radiation ,Radiation Exposure ,Total body irradiation ,Hematopoiesis ,Acute Radiation Syndrome ,Receptors, Estrogen ,Mechanism of action ,chemistry ,030220 oncology & carcinogenesis ,Nanoparticles ,medicine.symptom ,business ,Intramuscular injection - Abstract
There are no FDA-approved drugs that can be administered prior to ionizing radiation exposure to prevent hematopoietic–acute radiation syndrome (H-ARS). A suspension of synthetic genistein nanoparticles was previously shown to be an effective radioprotectant against H-ARS when administered prior to exposure to a lethal dose of total body radiation. Here we aimed to determine the time to protection and the duration of protection when the genistein nanosuspension was administered by intramuscular injection, and we also investigated the drug’s mechanism of action. A single intramuscular injection of the genistein nanosuspension was an effective radioprotectant when given prophylactically 48 h to 12 h before irradiation, with maximum effectiveness occurring when administered 24 h before. No survival advantage was observed in animals administered only a single dose of drug after irradiation. The dose reduction factor of the genistein nanosuspension was determined by comparing the survival of treated and untreated animals following different doses of total body irradiation. As genistein is a selective estrogen receptor beta agonist, we also explored whether this was a central component of its radioprotective mechanism of action. Mice that received an intramuscular injection of an estrogen receptor antagonist (ICI 182,780) prior to administration of the genistein nanosuspension had significantly lower survival following total body irradiation compared with animals only receiving the nanosuspension (P < 0.01). These data define the time to and duration of radioprotection following a single intramuscular injection of the genistein nanosuspension and identify its likely mechanism of action.
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- 2019
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44. Palladium-Catalyzed Synthesis of 4-Aminoquinazolines from Amide Oxime Ethers and 2-Iodobenzonitrile
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Regina M. Islamova, Vitalii V. Suslonov, and M. Ya. Demakova
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010405 organic chemistry ,Xantphos ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,Oxime ,01 natural sciences ,Medicinal chemistry ,0104 chemical sciences ,Catalysis ,chemistry.chemical_compound ,chemistry ,Amide ,Benzamide ,Palladium - Abstract
4-Substituted O-benzyl benzamide oximes reacted with 2-iodobenzonitrile in the presence of 0.1 mol % of [Pd2(dba)3], 0.2 mol % of XantPhos, and 1.5 equiv of Cs2CO3 in dioxane under argon to give 2-arylquinazolin-4-amines. The described reaction is a new type of cascade processes, which affords 4-amino-quinazoline derivatives without using highly reactive chlorinating agents.
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- 2019
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45. Rhodium(I)-catalysed cross-linking of polysiloxanes conducted at room temperature
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Andreas Roodt, Dumisani V. Kama, Vadim P. Boyarskiy, Mikhail V. Dobrynin, Regina M. Islamova, and Carla Pretorius
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010405 organic chemistry ,Hydrosilylation ,chemistry.chemical_element ,010402 general chemistry ,Silicone rubber ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Rhodium ,chemistry.chemical_compound ,Silicone ,chemistry ,Polymer chemistry ,Copolymer ,Physical and Theoretical Chemistry - Abstract
Acetylacetonate and 4-arylimino-2-pentanonate carbonyl complexes of rhodium(I) [Rh(RC(O)C(R')C(O)R“)(CO)2] (1: R = Me, R' = H, R'' = Me; 2: R = Me, R' = Cl, R'' = Me; 3: R = Me, R' = H, R'' = CO2Me; 4: R = Ph, R' = H, R'' = Me; 5: R = Ph, R' = H, R'' = Ph) and [Rh(MeC(NR''')CHC(O)Me)(CO)2] (6: R''' = Ph; 7: R''' = 2,6-Me2C6H3) were examined as hydrosilylation cross-linking catalysts at RT for the reaction of poly(dimethylsiloxane-co-ethylhydrosiloxane) copolymer with vinyl terminated poly(dimethylsiloxane) or vinyl terminated poly(dimethylsiloxane-co-styrene) copolymer. All complexes allow cross-linking of vinyl- and hydride-containing polysiloxanes and copolymers at RT without inhibitor addition. Complexes 1–7 possess catalytic activity comparable to the industrially used complex of Pt0 and divinyltetramethyldisiloxane (Karstedt’s catalyst). 1 is the most active among the studied rhodium complexes at 1.0 × 10−4 mol⋅L−1 and 1.0 × 10−5 mol⋅L−1. Silicone rubbers obtained with the rhodium catalysts compared to Karstedt’s catalyst possess no visible defects (bubbles or cracks), and differed by improved elastic properties (the elongation at break increased from 160 to 255%) The activity and improved silicone rubber properties using 1 renders it one of the suitable alternatives to Karstedt’s catalyst.
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- 2019
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46. BET bromodomain protein inhibition reverses chimeric antigen receptor extinction and reinvigorates exhausted T cells in chronic lymphocytic leukemia
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Jamie E. DeNizio, Yan Wang, Simon F. Lacey, Vijay Bhoj, Tyler J. Reich, In-Young Jung, Regina M. Young, David L. Porter, John Scholler, Minnal Gupta, Julie K. Jadlowsky, Carl H. June, Todd Yoder, Christopher J. Ott, Megan M. Davis, Kathleen M. Haines, Irina Kulikovskaya, Golnaz Vahedi, Katherine T. Marcucci, Weimin Kong, Jun Xu, J. Joseph Melenhorst, John K. Everett, Joseph A. Fraietta, Marcela V. Maus, Erik F. Williams, Bruce L. Levine, Wenliang Wang, James E. Bradner, Rahul M. Kohli, Alexander Dimitri, Frederic D. Bushman, and Maria Fasolino
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T-Lymphocytes ,T cell ,Chronic lymphocytic leukemia ,Antigens, CD19 ,Cell ,chemical and pharmacologic phenomena ,Immunotherapy, Adoptive ,Oxidative Phosphorylation ,Epigenesis, Genetic ,Immune Tolerance ,medicine ,Humans ,Gene silencing ,Receptor ,B cell ,Receptors, Chimeric Antigen ,Chemistry ,Proteins ,hemic and immune systems ,Azepines ,General Medicine ,Triazoles ,medicine.disease ,Leukemia, Lymphocytic, Chronic, B-Cell ,Chimeric antigen receptor ,Bromodomain ,medicine.anatomical_structure ,Cancer research ,Glycolysis ,Immunologic Memory ,Research Article - Abstract
Chimeric antigen receptor (CAR) T cells have induced remarkable antitumor responses in B cell malignancies. Some patients do not respond because of T cell deficiencies that hamper the expansion, persistence, and effector function of these cells. We used longitudinal immune profiling to identify phenotypic and pharmacodynamic changes in CD19-directed CAR T cells in patients with chronic lymphocytic leukemia (CLL). CAR expression maintenance was also investigated because this can affect response durability. CAR T cell failure was accompanied by preexisting T cell-intrinsic defects or dysfunction acquired after infusion. In a small subset of patients, CAR silencing was observed coincident with leukemia relapse. Using a small molecule inhibitor, we demonstrated that the bromodomain and extra-terminal (BET) family of chromatin adapters plays a role in downregulating CAR expression. BET protein blockade also ameliorated CAR T cell exhaustion as manifested by inhibitory receptor reduction, enhanced metabolic fitness, increased proliferative capacity, and enriched transcriptomic signatures of T cell reinvigoration. BET inhibition decreased levels of the TET2 methylcytosine dioxygenase, and forced expression of the TET2 catalytic domain eliminated the potency-enhancing effects of BET protein targeting in CAR T cells, providing a mechanism linking BET proteins and T cell dysfunction. Thus, modulating BET epigenetic readers may improve the efficacy of cell-based immunotherapies.
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- 2021
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47. Phthalates and Phenols, Leukocyte Telomere Length, and Breast Cancer Risk and Mortality in the Long Island Breast Cancer Study Project
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Regina M. Santella, Alfred I. Neugut, Jia Chen, Humberto Parada, Xueying Zhang, Susan L. Teitelbaum, Jing Shen, and Mary S. Wolff
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Oncology ,medicine.medical_specialty ,Epidemiology ,New York ,Phthalic Acids ,Breast Neoplasms ,Logistic regression ,Article ,chemistry.chemical_compound ,Breast cancer ,Phenols ,Risk Factors ,Internal medicine ,medicine ,Biomarkers, Tumor ,Leukocytes ,Humans ,Creatinine ,business.industry ,Proportional hazards model ,Phthalate ,Odds ratio ,Environmental Exposure ,Middle Aged ,Telomere ,medicine.disease ,Confidence interval ,chemistry ,Case-Control Studies ,Biomarker (medicine) ,Female ,business - Abstract
Background: Phthalates and phenols from the environment have been inconsistently associated with breast cancer risk or mortality. Studies on the potential modifying role of leukocyte telomere length (LTL), a biomarker of biological aging, on these associations are lacking. Methods: We included 1,268 women from the Long Island Breast Cancer Study Project with available data on phthalate and phenol analytes and LTL measurements. Twenty-two phthalate and phenol analytes were measured in spot urines and LTL was measured in blood. The modifying effect of LTL on the associations of individual analyte with breast cancer risk as well as mortalities was estimated using interaction terms between LTL and urinary concentrations of analyte in logistic regression and Cox regression models, respectively. ORs, HRs, and corresponding 95% confidence intervals for a one-unit (ln μg/g creatinine) increase of urinary phthalate/phenol level were estimated at 10th, 50th, and 90th percentiles of LTL. Results: LTL significantly (P < 0.05) modified associations between 11 of 22 of urinary phthalate/phenols analytes and breast cancer risk. An inverse association between phthalate/phenols analytes and breast cancer risk at shorter LTL and a positive association at longer LTL was generally suggested. No modifying effect was found for LTL on the association between these phthalate/phenols analytes and breast cancer mortalities. Conclusions: LTL may modify the associations between phthalate and phenol exposures and breast cancer risk. Impact: This study is the first study that determined the modifying effect of biological aging in the association between environmental chemical exposure and breast cancer risk.
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- 2021
48. Associations between efavirenz concentrations, pharmacogenetics and neurocognitive performance in people living with HIV in Nigeria
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Chinedum P. Babalola, Regina M. Tallerico, Jacinta N. Nwogu, Monica Gandhi, Andrew Owen, Saye Khoo, Hideaki Okochi, Kevin Robertson, Adeniyi Olagunju, Baiba Berzins, and Babafemi Taiwo
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Adult ,Cyclopropanes ,Male ,medicine.medical_specialty ,Efavirenz ,CYP2B6 ,Genotype ,Anti-HIV Agents ,Immunology ,Nigeria ,Single-nucleotide polymorphism ,HIV Infections ,neurocognitive performance ,Gastroenterology ,Polymorphism, Single Nucleotide ,chemistry.chemical_compound ,single nucleotide polymorphisms ,Pharmacokinetics ,Basic Science ,immune system diseases ,Internal medicine ,Immunology and Allergy ,Medicine ,Humans ,Adverse effect ,business.industry ,virus diseases ,efavirenz ,hair ,Benzoxazines ,Cytochrome P-450 CYP2B6 ,Infectious Diseases ,Cross-Sectional Studies ,chemistry ,Pharmacogenetics ,Alkynes ,dried blood spots ,Female ,business ,Neurocognitive - Abstract
Objective: Efavirenz (EFV) use is associated with neuropsychiatric side effects, which may include poor neurocognitive performance. We evaluated single nucleotide polymorphisms in genes that contribute to EFV pharmacokinetics and examined them in association with EFV concentrations in plasma and hair, as well as neurocognitive performance. Design: Cross-sectional study in which adults with HIV receiving 600-mg EFV for at least 2 months were recruited and paired hair and dried blood spots (DBS) samples collected. Methods: Participants (N = 93, 70.3% female) were genotyped for seven single nucleotide polymorphisms in CYP2B6, NRII3 and ABCB1 using DBS. EFV was quantified in DBS and hair using validated liquid-chromatography–tandem-mass-spectrometry methods, with plasma EFV concentrations derived from DBS levels. Participants were also administered a neurocognitive battery of 10 tests (seven domains) that assessed total neurocognitive functioning. Results: Strong correlation (r = 0.66, P T, (P C (P = 0.001) were each associated with hair EFV concentrations. Similarly, 516G>T (P C (P = 0.009) were significantly associated with plasma EFV concentration. No other genetic associations were observed. Contrary to other studies, total neurocognitive performance was significantly associated with plasma EFV concentrations (r = 0.23, P = 0.043) and 983T>C genotype (r = 0.38, P
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- 2021
49. Early acquisition of threat conditioning in a selectively-bred anxiety-like rat phenotype: regulation by maternal presence and FGF2
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Regina M. Sullivan, Cortney A. Turner, White Am, Daniel T. Chang, Hider Jh, Jacek Debiec, Elaine K. Hebda-Bauer, and Huda Akil
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Mechanism (biology) ,medicine.drug_class ,business.industry ,media_common.quotation_subject ,Anxiolytic ,Phenotype ,chemistry.chemical_compound ,chemistry ,Neurotrophic factors ,Corticosterone ,medicine ,Anxiety ,Temperament ,medicine.symptom ,business ,Neuroscience ,Pathological ,media_common - Abstract
Temperament is an innate, stable predisposition towards particular emotional and behavioral responses. In humans, certain temperaments are associated with a heightened risk of developing anxiety later in life. Non-human animals, including rodents, also exhibit innate, stable dispositions; these are referred to as behavioral phenotypes. The interaction between behavioral phenotype and early life adverse events is critical for the development of maladaptive anxiety. Rodent studies of typically developing animals have identified a number of mechanisms that protect against aversive experiences in early life. One such mechanism is an early life quiescence of threat learning, which protects against the effects of stress and facilitates safety and attachment learning. However, little is known about the factors that alleviate the effects of early life aversive events on phenotypes vulnerable to pathological anxiety. Here, we examined threat learning and the stress response in selectively-bred infant rats that show an anxiety-like phenotype relative to typically developing animals. We investigated the potential roles of maternal presence and the anxiolytic neurotrophic factor fibroblast growth factor 2 (FGF2) in regulating threat learning and the stress response in infant anxiety-like phenotype animals. We observed that rats selectively-bred for anxiety-like behaviors could acquire conditioned freezing earlier in life than typically developing animals. FGF2 administration on postnatal day 1 (PND 1) and maternal presence during threat conditioning were both capable of suppressing this early emergence of conditioned freezing. However, neither FGF2 nor maternal presence during threat conditioning were associated with reduced corticosterone levels during threat conditioning. Our results suggest that although an anxiety-like phenotype may be associated with early threat learning, environmental factors (such as maternal presence) and pharmacological intervention (such as modulation of the FGF2 system) may be capable of counteracting that early aversive learning. Interventions in vulnerable infants may thus decrease the impact of aversive events.
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- 2021
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50. Monitoring Active Sites for Hydrogen Evolution Reaction at Model Carbon Surfaces
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Regina M. Kluge, Ifan E. L. Stephens, Aliaksandr S. Bandarenka, Richard W. Haid, and Federico Calle-Vallejo
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Materials science ,carbon ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Atomic units ,Electrochemical energy conversion ,0104 chemical sciences ,Catalysis ,electrochemical scanning tunneling microscopy ,Chemical engineering ,chemistry ,Highly oriented pyrolytic graphite ,active sites ,engineering ,Noble metal ,Graphite ,Physical and Theoretical Chemistry ,0210 nano-technology ,Carbon - Abstract
Carbon is ubiquitous as an electrode material in electrochemical energy conversion devices. If used as support material, the evolution of H2 is undesired on carbon. However, recently carbon-based materials are of high interest as economic and eco-conscious alternative to noble metal catalysts. The targeted design of improved carbon electrode materials requires atomic scale insight into the structure of the sites that catalyse H2 evolution. This work demonstrates that electrochemical scanning tunnelling microscopy under reaction conditions (n-EC-STM) can monitor active sites of highly oriented pyrolytic graphite for the hydrogen evolution reaction. With down to atomic resolution, the most active sites in acidic medium are pinpointed near edge sites and defects, whereas the basal planes remain inactive. Density functional theory calculations support these findings and reveal that only specific defects on graphite are active. Motivated by these results, the extensive usage of n-EC-STM on doped carbon-based materials is encouraged to locate their active sites and guide the synthesis of enhanced electrocatalysts. The authors thank Prof. Plamen Atanassov (University of California, Irvine, USA) and Dr. Jun Maruyama (Osaka Research Institute of Industrial Science and Technology, Japan) for fruitful discussion regarding some experimental results. RMK, RWH and ASB acknowledge the financial support from the German Research Foundation (DFG), in the framework of the projects BA 5795/4-1 and BA 5795/3-1, and under Germany's Excellence Strategy–EXC 2089/1–390776260, cluster of excellence ‘e-conversion’. ASB acknowledges the funding from the European Union's Horizon 2020 research and innovation programme under grant agreement HERMES No. 952184. FCV acknowledges financial support from Spanish MICIUN through RTI2018-095460-B-I00 and María de Maeztu (MDM-2017-0767) grants and a Ramón y Cajal research contract (RYC-2015-18996), and also from Generalitat de Catalunya (grants 2017SGR13 and XRQTC). The use of supercomputing facilities at SURFsara was sponsored by NWO Physical Sciences, with financial support from NWO.
- Published
- 2021
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