bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of polymer molecular weight and addition of calcium stearate on response of MG63 osteoblast‐like cells to UHMWPE particles
Authors: Dean D. D. , Lohmann C. H. , Sylvia V. L. , Köster G. , Liu Y. , Schwartz Z. , Boyan B. D. 
Published: July 2002

AbstractPeriprosthetic osteolysis and implant loosening is associated with the presence of ultrahigh molecular weight polyethylene (UHMWPE) wear debris particles. Osteoblast phenotypic expression in vitro is affected by UHMWPE particles, suggesting that bone formation may also be affected by wear debris. Here we tested the hypothesis that the response of osteoblasts to UHMWPE can be modified by changes in UHMWPE particle chemistry. We used four different commercially available preparations of GUR UHMWPE particles to determine if chemical composition (±Ca‐stearate) or polymer molecular weight (3.1–4.2 million or 5.4–6.5 million g/mol) modulates osteoblast response. Particles were characterized by size distribution, morphology, and number of particles added to the culture medium. They had an average equivalent circle diameter ranging from 0.46–1.26 μm. MG63 cell response was assessed by measuring cell number, cellular and cell layer alkaline phosphatase, and prostaglandin E2 (PGE2) production. There were dose‐dependent effects of the particles on cell response. Cell number and PGE2 production were increased, while alkaline phosphatase specific activity was decreased. In addition, there was a marked difference between cultures treated with particles containing Ca‐stearate and as a function of polymer molecular weight. Particles of higher molecular weight caused a greater stimulation of proliferation and inhibition of alkaline phosphatase than particles of lower molecular weight. The presence of Castearate exerted a more pronounced depression of osteoblast phenotype as well as a significantly greater increase in PGE2 release by the cells. The present study shows that chemical composition and polymer molecular weight of UHMWPE are capable of modulating osteoblast response to particles. The results suggest that osteoblast differentiation is inhibited by UHMWPE particles, whereas cell proliferation and PGE2 production are stimulated. This may have direct effects on osteoblasts and bone formation, but also paracrine effects on cells of the monocytic lineage inducing bone resorption and promoting inflammation which may lead to aseptic loosening. The present results suggest that the cellular events in aseptic loosening may be modulated or even accelerated by changes in the composition of the UHMWPE used to fabricate implants. © 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Chronic depolarization induced by veratridine increases the survival of rat retinal ganglion cells ‘in vitro’
Authors: Fernandes Pereira Simão Pedro , Giestal de Araujo Elizabeth 
Published: July 2002

AbstractDuring the last decades it has been shown that trophic molecules released by target, afferent and glial cells play a pivotal role controlling neuronal cell death. Trophic molecules are able to inhibit this regressive event during development as well as during degenerative diseases. One of the mechanisms involved in the control of neuronal survival by afferent cells requires the release of trophic molecules stimulated by electrical activity. It has been demonstrated that veratridine (a depolarizing agent that keeps the Na+ channels opened) induces an increase in neuronal survival. In the present work we show that 3 μM veratridine induced a two‐fold increase on the survival of retinal ganglion cells after 48 h in culture. The veratridine effect was inhibited by 50 μM amiloride (an inhibitor of Ca2+ channels), 25 μM benzamil (an inhibitor of Na+ channels), 30 μM dantrolene and 7.5 μM caffeine (both inhibitors of Ca2+ release from the endoplasmatic reticulum) and 10 μM BAPTA‐AM (an intracellular Ca2+ chelator). However, 5 μM nifedipine (a selective inhibitor of voltage‐dependent l‐type Ca2+ channels) and 100 μM MK 801 (an inhibitor of NMDA receptors) did not block the veratridine effect. On the other hand, treatment with 10 μM genistein (an inhibitor of tyrosine kinase enzymes), 20 μM fluorodeoxyuridine (an inhibitor of cell proliferation) or 10 μM atropine (an antagonist of muscarinic receptors) completely abolished the effect of veratridine. Taken together, our results indicate that veratridine increases the survival of rat retinal ganglion cells through mechanisms involving Na+ influx, intracellular Ca2+ release, activation of tyrosine kinase enzymes and cellular proliferation. They also indicate that cholinergic activity plays an important role in the veratridine effect.
Cholinergic activity modulates the survival of retinal ganglion cells in culture: the role of M1 muscarinic receptors
Authors: Pereira S.P.F. , Medina S.V. , Araujo E.G. 
Published: July 2002

AbstractThe control of natural cell death is mediated by neurotrophins released by target, afferent and glial cells. In the present work we show that treatment of retinal cells ‘in vitro’ for 48 h with 25 μM carbamylcholine induced a two‐fold increase in retinal ganglion cells survival. This effect was dose‐dependent and mediated by M1 receptors since it could be blocked by 1 μM telenzepine (a M1 receptor antagonist) and mimicked by 200 μM oxotremorine (a M1 receptor agonist). The effect of carbamylcholine was abolished by 10 μM BAPTA‐AM (an intracellular Ca2+ chelator), 30 μM dantrolene (an inhibitor of ryanodinic receptors), 500 nM H‐89 (an inhibitor of PKA), 1.25 μM chelerythrine chloride (an inhibitor of PKC) and 50 μM PD‐98059 (a MEK inhibitor). Treatment with 10 μM genistein (an inhibitor of tyrosine kinase), 25 μM LY‐294002 (a PI‐3 kinase blocker), 30 nM brefeldin‐A (a blocker of polypeptides release), 50 nM K‐252a (a Trk receptor inhibitor) and 20 μM fluorodeoxyuridine (an inhibitor of cell proliferation) totally inhibited the effect of carbamylcholine. Taken together our results indicate that muscarinic activity controls the survival of retinal ganglion cells through a mechanism involving the release of polypeptides and activation of Irk receptors.
Rating antidepressant efficacy with naturalistic live versus structured videotaped interviews
Authors: Corruble E , Sabran V , Payan C , Puech AJ , Fermanian J , Guelfi JD 
Published: July 2002

SummaryTwo different methods were compared in the assessment of depressive symptomatology improvement: live naturalistic (N) performed by the patient's therapist, and from videotape record of structured clinical interview (VSI) assessed by an independent rater out of five psychiatrists.Sixty-one newly admitted depressed inpatients, with a Montgomery and Asberg Depression Rating Scale (MADRS) total score above 20, were assessed before antidepressant treatment (DO), after 10 days (D10) and 4 weeks of treatment (D28). Assessments were based on the MADRS and the Depression Retardation Rating Scale (DRRS) for both N and VSI methods, and on the SCL-90-R for self-rating.With the MADRS, the N method was shown to be more sensitive to symptomatology change than the VSI method, but the VSI method was more correlated to self-assessment than the N method was. However, these results were not replicated on the DRRS, for which an underscoring with the VSI method was evidenced as compared to the N method.As shown in other studies, the poorest agreement between the two methods was evidenced at DO, suggesting a “novelty effect” particularly with the VSI method. This “novelty effect” may be all the more pronounced if a personality disorder is associated to depression. Consequently, information concerning each patient before rating videotapes is needed, as well as investigations in the field of depression and personality disorders.The greater change observed in MADRS with the N method as compared to the VSI method, may be due non-specific factors related mostly to therapist expectations by comparison to neutral raters. This hypothesis should be tested in the placebo group of a double-blind study, and, if confirmed, the use of VSI methods, by minimising non-specific factors of improvement due to therapist expectations, may decrease the placebo response in antidepressant drug trials.
HIV IN OLDER AMERICANS: AN EPIDEMIOLOGIC PERSPECTIVE
Authors: Lieberman Rochel 
Published: July 2002

ABSTRACTThe elderly population is increasing as baby boomers are beginning to approach retirement. People 65 years of age or older already constitute approximately one eighth of the U.S. population; this proportion is expected to double in the next 50 years. Older Americans have their own population‐specific health challenges, such as Alzheimer's disease, osteoporosis, adult‐onset diabetes, prostate cancer, menopause, and hypertension. Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are seldom discussed within this community. Prevention, counseling, testing, and education efforts are not being directed their way. In addition, few practitioners are experts both in HIV and health problems associated with aging, resulting in misdiagnosis, especially in the early stages when AIDS symptoms such as fatigue, weight loss, night sweats, and diminished appetite are dismissed as part of the aging process.Very few HIV‐related social support services have been aimed at the needs of the elderly, perhaps because older Americans are not suspected to be sexually active or are assumed to be in a monogamous, heterosexual relationship. Older Americans are not suspected of drug use. Yet many are sexually active, often demonstrating risky sexual behavior, such as dispensing with the use of condoms; and the isolation that frequently accompanies old age can lead to alcoholism and injectable drug use.This article examines methods suggested in the literature both in terms of primary and secondary prevention of HIV/AIDS in older Americans. The cost of these efforts is enumerated, and organizations who gear their efforts in reaching and educating older Americans regarding their risks are described.
Ninjaflex vs Superflab: A comparison of dosimetric properties, conformity to the skin surface, Planning Target Volume coverage and positional reproducibility for external beam radiotherapy
Authors: Robertson Fiona M. , Couper Megan B. , Kinniburgh Margaret , Monteith Zoe , Hill Gareth , Pillai Sanka Andiappa , Adamson Douglas J. A. 
Published: March 2021

AbstractBackground and purposeWhen planning and delivering radiotherapy, ideally bolus should be in direct contact with the skin surface. Varying air gaps between the skin surface and bolus material can result in discrepancies between the intended and delivered dose. This study assessed a three‐dimensional (3D) printed flexible bolus to determine whether it could improve conformity to the skin surface, reduce air gaps, and improve planning target volume coverage, compared to a commercial bolus material, Superflab.Materials and methodsAn anthropomorphic head phantom was CT scanned to generate photon and electron treatment plans using virtual bolus. Two 3D printing companies used the material Ninjaflex to print bolus for the head phantom, which we designated Ninjaflex1 and Ninjaflex2. The phantom was scanned a further 15 more times with the different bolus materials in situ allowing plan comparison of the virtual to physical bolus in terms of planning target volume coverage, dose at the prescription point, skin dose, and air gap volumes.ResultsSuperflab produced a larger volume and a greater number of air gaps compared to both Ninjaflex1 and Ninjaflex2, with the largest air gap volume of 12.02 cm3. Our study revealed that Ninjaflex1 produced the least variation from the virtual bolus clinical goal values for all modalities, while Superflab displayed the largest variances in conformity, positional accuracy, and clinical goal values. For PTV coverage Superflab produced significant percentage differences for the VMAT and Electron3 plans when compared to the virtual bolus plans. Superflab also generated a significant difference in prescription point dose for the 3D conformal plan.ConclusionCompared to Superflab, both Ninjaflex materials improved conformity and reduced the variance between the virtual and physical bolus clinical goal values. Results illustrate that custom‐made Ninjaflex bolus could be useful clinically and may improve the accuracy of the delivered dose.
Core‐Shell Faujasite@Aqueous Miscible Organic‐Layered Double Hydroxides Composites with Tunable Acid/Base Properties for One‐Pot Synthesis of Ethyl trans‐α‐Cyanocinnamate
Authors: Rodaum Chadatip , Suttipat Duangkamon , Morey Julien , Atithep Thassanant , Witoon Thongthai , Wattanakit Chularat 
Published: March 2021

AbstractBifunctional acid‐base catalysts have been developed by fabricating core‐shell faujasite@aqueous miscible organic‐layered double hydroxides (FAU@AMO‐LDHs) composites via the growth of AMO‐LDHs on zeolite surfaces. Interestingly, by adjusting the acid/base properties of the composites, the one‐pot synthesis of ethyl trans‐α‐cyanocinnamate via deacetalization‐Knoevenagel reaction can be achieved up to 90% yield. In contrast, almost no desired products can be observed in cases of isolated zeolites and AMO‐LDHs, demonstrating the synergistic effect of zeolites and AMO‐LDHs as acid‐base catalysts. These findings open up new perspectives of the development of tunable acid‐base zeolite@LDHs composites in an acid‐base tandem reaction, which can selectively produce ethyl trans‐α‐cyanocinnamate up to 90% yield.
Photogenerated Charge Separation between Polar Crystal Facets Under a Spontaneous Electric Field
Authors: Liu Bin , Yang Heqing , Liu Shengzhong 
Published: March 2021

AbstractUntil now, the photogenerated charge separation mechanism is not clear in photocatalysis. Based on the structures at the atomic scale of the polar crystal facets with photocatalytic activities, a general separation model of photogenerated charge between polar facets under a spontaneous electric field is presented. This charge separation model is proven by photo‐induced selective redox reactions on polar planes, photovoltaic and rectification effects in the polar direction orientated thin films, and electric field assisted assembly and alignment of semiconductor nanowires grown along the polar direction. This polar structure is similar to a semiconductor p–n junction, which can control the movement of electronic carriers and can be used to fabricate high‐efficiency photocatalysts and electronic and optoelectronic devices based on a new principle.
Designing Rules and Optimization of Triboelectric Nanogenerator Arrays
Authors: Shao Jiajia , Yang Yi , Yang Ou , Wang Jie , Willatzen Morten , Wang Zhong Lin 
Published: March 2021

AbstractA triboelectric nanogenerator (TENG) is an effective means for the conversion of mechanical energy into electricity. Although Maxwell's displacement current is the underline mechanism of TENGs, the spatial and temporal variations of the electric field and electric displacement remain elusive, which prohibits an effective optimization of the energy conversion process. Here, the electric field distribution and energy dynamics of TENGs is determined using 3D mathematical modeling. The electrical energies stored in TENGs and extracted into the external circuit are calculated quantitatively whereby the ratio of the two, defined as the output efficiency, is obtained. Then, the power density and energy density of TENGs are defined. Utilizing the principle of virtual work, the minimum required external force–time relationship is evaluated. The influence of device parameters, geometry, and optimum conditions are discussed systematically so as to determine general optimization guidelines for TENGs. In addition, although the fringing electric field is practically inevitable, adjustments of the gap distance between neighboring TENG devices to assure that an optimized fringing electric field is “leaked”, is demonstrated to lead to improvement in a TENG array. Then, for the first time, this work presents universal design rules and holistic optimization strategies for the network structure of TENGs.
Multiple SclerosisIs Rare in Epstein–Barr Virus–Seronegative Children withCentral Nervous SystemInflammatory Demyelination
Authors: Nourbakhsh Bardia , Cordano Christian , Asteggiano Carlo , Ruprecht Klemens , Otto Carolin , Rutatangwa Alice , Lui Allysa , Hart Janace , Flanagan Eoin P. , James Judith A. , Waubant Emmanuelle 
Published: March 2021

Although Epstein–Barr virus (EBV) is hypothesized to be a prerequisite for multiple sclerosis (MS), up to 15% of children with a diagnosis of MS were reported to be EBV‐seronegative. When re‐evaluating 25 EBV‐seronegative children out of 189 pediatric patients with a diagnosis of clinically isolated syndrome/MS, we found anti–myelin oligodendrocyte glycoprotein (MOG) antibody in 11 of 25 (44%) EBV‐seronegative but only 9 of 164 (5.5%,p < 0.001) EBV‐seropositive patients. After critical review, MS remained a plausible diagnosis in only 4 of 14 EBV‐seronegative/MOG antibody–negative patients. In children with an MS‐like presentation, EBV seronegativity should alert clinicians to consider diagnoses other than MS, especially MOG‐antibody disease. ANN NEUROL 2021;89:1234–1239
Solvent‐Switched Oxidation Selectivities with O2: Controlled Synthesis of α‐Difluoro(thio)methylated Alcohols and Ketones
Authors: Liu Chi , Zhu Chuanle , Cai Yingying , Jiang Huanfeng 
Published: March 2021

AbstractThe solvent‐switched hydroxylation and oxygenation of α‐difluoro(thio)methylated carbanions with molecular oxygen under mild conditions are reported. This strategy tames the redox reactions of the in situ generated hydroperoxy difluoromethylsulfides, in which solvent‐bonding can alter their reactivity and switch the oxidation selectivities. These controllable three‐component reactions of gem‐difluoroalkenes, thiols and molecular oxygen afford various useful α‐difluoro(thio)methylated alcohols and ketones in high yields. Significantly, this protocol has been applied in the synthesis different bioactive molecules. Mechanism studies enable the detection of the hydroperoxy difluoromethylsulfide intermediates and exclude the thiol‐based radical pathway.
Chemically Fueled Self‐Assembly in Biology and Chemistry
Authors: Das Krishnendu , Gabrielli Luca , Prins Leonard J. 
Published: March 2021

AbstractLife is a non‐equilibrium state of matter maintained at the expense of energy. Nature uses predominantly chemical energy stored in thermodynamically activated, but kinetically stable, molecules. These high‐energy molecules are exploited for the synthesis of other biomolecules, for the activation of biological machinery such as pumps and motors, and for the maintenance of structural order. Knowledge of how chemical energy is transferred to biochemical processes is essential for the development of artificial systems with life‐like processes. Here, we discuss how chemical energy can be used to control the structural organization of organic molecules. Four different strategies have been identified according to a distinguishable physical‐organic basis. For each class, one example from biology and one from chemistry are discussed in detail to illustrate the practical implementation of each concept and the distinct opportunities they offer. Specific attention is paid to the discussion of chemically fueled non‐equilibrium self‐assembly. We discuss the meaning of non‐equilibrium self‐assembly, its kinetic origin, and strategies to develop synthetic non‐equilibrium systems.
An Efficient Interfacial Synthesis of Two‐Dimensional Metal–Organic Framework Nanosheets for Electrochemical Hydrogen Peroxide Production
Authors: Wang Mengjun , Dong Xu , Meng Zhaodong , Hu Zhiwei , Lin Yan‐Gu , Peng Chun‐Kuo , Wang Hongshuai , Pao Chih‐Wen , Ding Songyuan , Li Youyong , Shao Qi , Huang Xiaoqing 
Published: March 2021

AbstractTwo‐dimensional (2D) metal–organic framework nanosheets (MOF NSs) play a vital role in catalysis, but the most preparation is ultrasonication or solvothermal. Herein, a liquid–liquid interfacial synthesis method has been developed for the efficient fabrication of a series of 2D Ni MOF NSs. The active sites could be modulated by readily tuning the ratios of metal precursors and organic linkers (RM/L). The Ni MOF NSs display highly RM/L dependent activities towards 2e oxygen reduction reaction (ORR) to hydrogen peroxide (H2O2), where the Ni MOF NSs with the RM/L of 6 exhibit the optimal near‐zero overpotential, ca. 98 % H2O2 selectivity and production rate of ca. 80 mmol gcat−1 h−1 in 0.1 M KOH. As evidenced by X‐ray absorption fine structure spectroscopy, the coordination environment of active sites changed from saturation to unsaturation, and the partially unsaturated metal atoms are crucial to create optimal sites for enhancing the electrocatalysis.
Enzyme‐like Supramolecular Iridium Catalysis Enabling C−H Bond Borylation of Pyridines with meta‐Selectivity
Authors: Trouvé Jonathan , Zardi Paolo , Al‐Shehimy Shaymaa , Roisnel Thierry , Gramage‐Doria Rafael 
Published: March 2021

AbstractThe use of secondary interactions between substrates and catalysts is a promising strategy to discover selective transition metal catalysts for atom‐economy C−H bond functionalization. The most powerful catalysts are found via trial‐and‐error screening due to the low association constants between the substrate and the catalyst in which small stereo‐electronic modifications within them can lead to very different reactivities. To circumvent these limitations and to increase the level of reactivity prediction in these important reactions, we report herein a supramolecular catalyst harnessing Zn⋅⋅⋅N interactions that binds to pyridine‐like substrates as tight as it can be found in some enzymes. The distance and spatial geometry between the active site and the substrate binding site is ideal to target unprecedented meta‐selective iridium‐catalyzed C−H bond borylations with enzymatic Michaelis–Menten kinetics, besides unique substrate selectivity and dormant reactivity patterns.
Hierarchical Metal–Polymer Hybrids for Enhanced CO2Electroreduction
Authors: Jia Shuaiqiang , Zhu Qinggong , Chu Mengen , Han Shitao , Feng Ruting , Zhai Jianxin , Xia Wei , He Mingyuan , Wu Haihong , Han Buxing 
Published: March 2021

AbstractThe design of catalysts with high activity, selectivity, and stability is key to the electroreduction of CO2. Herein, we report the synthesis of 3D hierarchical metal/polymer–carbon paper (M/polymer‐CP) electrodes by in situ electrosynthesis. The 3D polymer layer on CP (polymer‐CP) was first prepared by in situ electropolymerization, then a 3D metal layer was decorated on the polymer‐CP to produce the M/polymer‐CP electrode. Electrodes with different metals (e.g. Cu, Pd, Zn, Sn) and various polymers could be prepared by this method. The electrodes could efficiently reduce CO2to desired products, such as C2H4, CO, and HCOOH, depending on the metal used. For example, C2H4could be formed with a Faradaic efficiency of 59.4 % and a current density of 30.2 mA cm−2by using a very stable Cu/PANI‐CP electrode in an H‐type cell. Control experiments and theoretical calculations showed that the 3D hierarchical structure of the metals and in situ formation of the electrodes are critical for the excellent performance.
Copper‐Catalyzed Borylative Methylation of Alkyl Iodides with CO as the C1 Source: Advantaged by Faster Reaction of CuH over CuBpin
Authors: Wu Fu‐Peng , Wu Xiao‐Feng 
Published: March 2021

AbstractCuH and CuBpin are versatile catalysts and intermediates in organic chemistry. However, studies that involve both CuH and CuBpin in the same reaction is still rarely reported due to their high reactivity. Now, a study on CuH‐ and CuBpin‐catalyzed borylative methylation of alkyl iodides with CO as the C1 source is reported. Various one carbon prolongated alkyl boranes (RCH2Bpin and RCH(Bpin)2) were produced in moderate to good yields from the corresponding alkyl iodides (RI). In this cooperative system, CuH reacts with alkyl iodide faster than CuBpin.