bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluoroartemisinins: Metabolically More Stable Antimalarial Artemisinin Derivatives
Authors: Bégué Jean‐Pierre , Bonnet‐Delpon Danièle 
Published: January 2007

AbstractThis report is an overview on the design, preparation, and evaluation of metabolically stable artemisinins, using fluorine substitution. The chemical challenges encountered for the incorporation of fluorine‐containing elements and the preparation of a large range of 10‐trifluoromethyl artemisinin derivatives are detailed. Impact of the fluorine substitution on the antimalarial activity is also highlighted. Preclinical data of lead compounds, and evidence for their strong and prolonged antimalarial activity are presented.
Chemical Tools to Investigate Sphingolipid Metabolism and Functions
Authors: Delgado Antonio , Casas Josefina , Llebaria Amadeu , Abad José Luis , Fabriás Gemma 
Published: January 2007

AbstractSphingolipids comprise an important group of biomolecules, some of which have been shown to play important roles in the regulation of many cell functions. From a structural standpoint, they all share a long 2‐amino‐1,3‐diol chain, which can be either saturated (sphinganine), hydroxylated at C4 (phytosphingosine), or unsaturated at C4 (sphingosine) as in most mammalian cells. N‐acylation of sphingosine leads to ceramide, a key intermediate in sphingolipd metabolism that can be enzymatically modified at the C1‐OH position to other biologically important sphingolipids, such as sphingomyelin or glycosphingolipids. In addition, both ceramide and sphingosine can be phosphorylated at C1‐OH to give ceramide‐1‐phosphate and sphingosine‐1‐phosphate, respectively. To better understand the biological and biophysical roles of sphingolipids, many efforts have been made to design synthetic analogues as chemical tools able to unravel their structure–activity relationships, and to alter their cellular levels. This last approach has been thoroughly studied by the development of specific inhibitors of some key enzymes that play an important role in biosynthesis or metabolism of these intriguing lipids. With the above premises in mind, the aim of this review is to collect, in a systematic way, the recent efforts described in the literature leading to the development of new chemical entities specifically designed to achieve the above goals.
Cells meeting our immunophenotypic criteria of endothelial cells are large platelets
Authors: Strijbos Michiel H. , Kraan Jaco , den Bakker Michael A. , Lambrecht Bart N. , Sleijfer Stefan , Gratama Jan W. 
Published: January 2007

AbstractBackgroundCirculating endothelial cells (CEC) are shed from damaged vasculature, making them a rational choice to serve as surrogate marker for vascular damage. Currently, various techniques and CEC definitions are in use, and their standardization and validation is needed. A flow cytometric single platform assay defining CEC as forward light scatter (FSC)low‐to‐intermedate, sideward light scatter (SSC)low, CD45−, CD31++ and CD146+ is a promising approach to enumerate CEC because of its simplicity (Mancuso et al., Blood 2001;97:3658–3661). Here, we set out to confirm the endothelial nature of these cells.MethodsWe isolated cells with a FSClow‐to‐intermediate, SSClow, CD31++, CD45dim immunophenotype (termed “cells meeting our immunophenotypic criteria for endothelial cells” [CMOIC]) from healthy donors to study the expression of endothelium‐associated markers using several techniques. Special attention was paid to reagents identifying the endothelial cell‐specific marker CD146. We compared antigen expression patterns of CMOIC with those of the HUVEC endothelial cell line and lymphocytes. Electron microscopy was used to detect the presence of endothelial cell‐specific Weibel–Palade bodies in the sorted cells.ResultsCD146 expression was negative on CMOIC for all tested CD146 mAbs, but positive on HUVEC cells and a minor subset of T lymphocytes. Using flow cytometry, we found no expression of any endothelium‐associated marker except for CD31 and CD34. HUVEC cells were positive for all endothelial markers except for CD34. Evaluation of CMOIC morphology showed a homogenous population of cells with a highly irregular nucleus‐like structure and positive endothelial immunohistochemistry. CMOIC contained neither nuclei nor DNA. Electron microscopy revealed the absence of a nucleus, the absence of endothelial specific Weibel–Palade bodies, and revealed CMOIC to be large platelets.ConclusionThe vast majority of cells with the immunophenotype FSClow‐to‐intermediate, SSClow, CD45−, CD31++ do not express CD146 and are large platelets rather than endothelial cells. © 2007 Clinical Cytometry Society.
Exposure to environmental enrichment elicits differential hippocampal cell proliferation: Role of individual responsiveness to anxiety
Authors: Leal‐Galicia Perla , Saldívar‐González Alfredo , Morimoto Sumiko , Arias Clorinda 
Published: January 2007

AbstractEnvironmental enrichment (EE) is a largely employed behavioral procedure in which animals are exposed to high stimulation compared with conventional housing conditions. Animal exposure to an EE exerts beneficial effects on the performance of different learning tasks and induces a number of behavioral, neurochemical, and neuroanatomical changes including hippocampal cell proliferation. However, the importance of voluntary interaction with the environment in these changes has not been clearly resolved yet. Moreover, the effects of a complex environment on animal emotionality still remains questionable and has not been explored in detail under conditions that allow unmasking individual responses among subjects in a group. The present study was aimed at exposing groups of rats to an EE, and analyzing individual differences in activity levels during EE sessions. We observed differences with respect to the activity level displayed by rats during the enriched sessions, which correlated with differences in the rate of hippocampal cell proliferation. It is suggested that exposure to EE may reduce anxiety‐like behaviors and may elicit individual differences on emotional reactions positively linked with hippocampal neurogenesis and testosterone levels. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Sexually dimorphic SCAMP1 expression in the forebrain motor pathway for song production of juvenile zebra finches
Authors: Tang Yu Ping , Peabody Camilla , Tomaszycki Michelle L. , Wade Juli 
Published: January 2007

AbstractMechanisms regulating sexual differentiation of the zebra finch song system are not well understood. The present study was designed to more fully characterize secretory carrier membrane protein 1 (SCAMP1), which was identified in a cDNA microarray screen as showing increased expression in the forebrains of developing male compared with female zebra finches. We completed the sequence of the open reading frame and used in situ hybridization to compare mRNA in song control regions of juvenile (25‐day‐old) individuals. Expression was significantly greater in the HVC (used as a proper name) and robust nucleus of the arcopallium (RA) in males than in females. Immunohistochemistry revealed that SCAMP1 protein is also expressed in these two brain regions, and qualitatively appears greater in males. Western analysis confirmed that the protein is increased in the telencephalon of males when compared with females at 25 days of age. These results are consistent with the idea that SCAMP1 is involved in masculinization of these brain areas, perhaps facilitating the survival of cells within them. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Gaseous neuromodulator‐related genes expressed in the brain of honeybee Apis mellifera
Authors: Watanabe Takayuki , Kikuchi Mika , Hatakeyama Dai , Shiga Takumi , Yamamoto Takehiro , Aonuma Hitoshi , Takahata Masakazu , Suzuki Norio , Ito Etsuro 
Published: January 2007

AbstractNitric oxide (NO), hydrogen sulfide (H2S), and carbon monoxide (CO) are thought to act as gaseous neuromodulators in the brain across species. For example, in the brain of honeybee Apis mellifera, NO plays important roles in olfactory learning and discrimination, but the existence of H2S‐ and CO‐mediated signaling pathways remains unknown. In the present study, we identified the genes of nitric oxide synthase (NOS), soluble guanylyl cyclase (sGC), cystathionine β‐synthase (CBS), and heme oxygenase (HO) from the honeybee brain. The honeybee brain contains at least one gene for each of NOS, CBS, and HO. The deduced proteins for NOS, CBS, and HO are thought to contain domains to generate NO, H2S, and CO, respectively, and to contain putative Ca2+/calmodulin‐binding domains. On the other hand, the honeybee brain contains three subunits of sGC: sGCα1, sGCβ1, and sGCβ3. Phylogenetic analysis of sGC revealed that Apis sGCα1 and sGCβ1 are closely related to NO‐ and CO‐sensitive sGC subunits, whereas Apis sGCβ3 is closely related to insect O2‐sensitive sGC subunits. In addition, we performed in situ hybridization for Apis NOS mRNA and NADPH‐diaphorase histochemistry in the honeybee brain. The NOS gene was strongly expressed in the optic lobes and in the Kenyon cells of the mushroom bodies. NOS activity was detected in the optic lobes, the mushroom bodies, the central body complex, the lateral protocerebral lobes, and the antennal lobes. These findings suggest that NO is involved in various brain functions and that H2S and CO can be endogenously produced in the honeybee brain. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal Ligand
Authors: Fischbach Urs , Rüegger Heinz , Grützmacher Hansjörg 
Published: January 2007

AbstractThe tetradendate phosphane tris(5H‐dibenzo[a,d]cyclohepten‐5‐yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5‐chloro‐5H‐dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X‐ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky κ1‐phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (Ω = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M→C=Ctrop) and δ(31P) decreases with increasing M→C=Ctrop in the order 9 (δ = 260 ppm) > 7 (δ = 196 ppm) > 6 (δ = 135 ppm) > 3 (δ = –30.9 ppm). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Spin‐Crossover Studies on a Series of 1D Chain and Dinuclear Iron(II) Triazine‐Dipyridylamine Compounds
Authors: Neville Suzanne M. , Leita Ben A. , Offermann Daniel A. , Duriska Martin B. , Moubaraki Boujemaa , Chapman Karena W. , Halder Gregory J. , Murray Keith S. 
Published: January 2007

AbstractFour isostructural one‐dimensional polymeric iron(II) spin crossover materials containing the ligand 2‐chloro‐4,6‐bis(dipyrid‐2‐ylamino)‐1,3,5‐triazine (cddt) have been synthesised and magnetically and structurally characterised. The polymeric material Fe(NCS)2(cddt)·n(guest) (1), self assembles into three crystallographically distinct phases; the compounds 1b and 1c, [Fe(NCS)2(cddt)]·2(CH3OH), are polymorphs, however, 1a, [Fe(NCS)2(cddt)]·1/2(CHCl3)·(H2O) contains a different solvent system. Each phase shows very different magnetic behaviour; phases 1a and 1b remain high spin over all temperatures, whilst phase 1c undergoes a “half” spin crossover between 225 and 125 K. The structural consequences of the spin transition in 1c have been followed using variable temperature synchrotron powder X‐ray diffraction techniques. Variation of the chalcogenide ligand in the complex [Fe(NCSe)2(cddt)]·2(CH3OH), 2, leads to a full one‐step spin crossover with a T1/2 of 200 K. Structural analysis of 1c below the transition temperature reveals alternating, crystallographically distinct, HS and LS iron(II) centres (HS: high spin, LS: low spin) along the chain, and structural analysis of 2 below the transition temperature reveals all LS iron(II) centres. Also reported are the structural characterisations of two dinuclear materials, containing the ligand 2,4,6‐tris(dipyridin‐2‐ylamino)‐1,3,5‐triazine (tdt), of the formula [Fe(tdt)(X)2]2·(ClO4)·(solvent) (X = H2O, Cl– for 3a, 3b) which are analogous to those recently reported by Gamez et al. In addition, the structural characterisations are described for dinuclear materials, containing the ligand cddt, of the formula [Fe(cddt)(Cl)(X)]2·(Y)2·n(solvent) (X: H2O or NCCH3, Y: ClO4–, BF4– 4a, 4b and 4d) and for a cobalt(II) analogue, [Co(cddt)(Cl)(H2O)]2·(BF4)2·n(solvent) (4c).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A microtiter plate‐based assay method to determine fat quality
Authors: Bertram Mark , Manschot‐Lawrence Corrine , Flöter Eckhard , Bornscheuer Uwe T. 
Published: January 2007

AbstractA microtiter plate (MTP) method was developed to determine the quality of fats that are used in large‐scale processing using lipase catalysis. Two assay formats were followed: In the first approach, the fats were interesterified with p‐nitrophenol laurate using a lipase from Thermomyces lanuginosa; in the second approach, pH indicators were added to the fat samples containing lipase. A blind study using 29 fats showed that the MTP method using p‐nitrophenol as pH indicator allowed a rapid and reliable assignment of bad fats and an acceptable differentiation between fats of moderate and good quality.
Mild and Ligand‐Free Palladium‐Catalyzed Cross‐Couplings between Aryl Halides and Arylboronic Acids for the Synthesis of Biaryls and Heterocycle‐Containing Biaryls
Authors: Deng Chen‐Liang , Guo Sheng‐Mei , Xie Ye‐Xiang , Li Jin‐Heng 
Published: January 2007

AbstractLigand‐free palladium‐catalyzed Suzuki–Miyaura cross‐couplings between aryl halides and arylboronic acids performed at room temperature are presented. It was found that both solvent and base had a fundamental influence on the reaction, and the most effective system in terms of yield and rate was observed to be the combination of Pd(OAc)2 with MeONa and alcohols. In the presence of Pd(OAc)2 and MeONa, a variety of aryl halides reacted very rapidly with arylboronic acids in good to excellent yields at room temperature in EtOH as the solvent. Moreover, the Pd(OAc)2/MeONa catalytic system could also be applied in couplings between heteroaryl halides and arylboronic acids to provide satisfactory results in MeOH as the solvent after prolonged reaction times. It is noteworthy that the reactions were conducted under mild, aerobic, and ligand‐free conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
From Allenes to Tetracenes: A Synthetic and Structural Study of Silyl‐ and Halo‐Allenes and Their Dimers
Authors: Banide Emilie V. , Molloy Bevin C. , Ortin Yannick , Müller‐Bunz Helge , McGlinchey Michael J. 
Published: January 2007

Abstract9‐Alkynylfluoren‐9‐ols of type C13H8(OH)–C≡C–R, where R is phenyl (1a), p‐tolyl (1b), p‐methoxyphenyl (1c), or trimethylsilyl (1d), react with HBr to yield the corresponding bromoallenes C12H8C=C=C(Br)R (13a–d). Lithiation and hydrolysis of 13d yields 3,3‐(biphenyl‐2,2′‐diyl)‐1‐(trimethylsilyl)allene (20), which forms successively the head‐to‐tail dimer 1‐(9‐fluorenylidene)‐4‐(trimethylsilyl)‐2‐[(trimethylsilyl)methylene]spiro[cyclobutane‐3,9′‐[9H]fluorene] (21) and the tail‐to‐tail dimer trans‐3,4‐bis(trimethylsilyl)‐1,2‐di(fluorenylidene)cyclobutane (23) both of which exhibit long (ca. 1.6 Å) C(3)–C(4) bonds. Treatment of 21 and 23 with TBAF brings about desilylation to 22 and 24, respectively. In the latter case, removal of the bulky trimethylsilyl groups reduces the C(3)–C(4) bond length in 1,2‐di(fluorenylidene)cyclobutane (24) to a more normal value of 1.547 Å; however, the large wingspan of the severely overlapping fluorenylidene moieties retains the C2 symmetry of the system. Prolonged exposure to sunlight of the disilylated head‐to‐tail dimer 21 results in homolysis of the long C(3)–C(4) bond, generation of a peroxide, and ultimately formation of the lactol 25. X‐ray crystallographic data are reported for, among others, 1c, 13a, 21, 22, 23, 24, 25, and also for 3,3‐(biphenyl‐2,2′‐diyl)‐1‐chloroallene (12).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Asymmetrical consequences of behavioral change through reward and punishment
Authors: Greitemeyer Tobias , Kazemi Ellie 
Published: January 2007

AbstractPrevious research (Greitemeyer & Weiner, 2003) has demonstrated that compliance, because of an anticipated reward is attributed more to the person than compliance because of an anticipated punishment. The present research extended these findings to an educational context. Three studies revealed that parents who ask their children to change inappropriate behaviors are more likely to ascribe their children's improvement to the child, if the child was promised a reward, rather than threatened, to receive a punishment if the child did not improve. Moreover, because a child's improved behavior is more likely to be ascribed to the child given a reward as compared to a punishment, parents expect that rewards (as opposed to punishments) are more likely to sustain improved behavior, when the incentive is no longer offered. Finally, participants report to be more likely to induce behavioral change through reward rather than punishment. Copyright © 2007 John Wiley & Sons, Ltd.
Attitude learning through exploration: advice and strategy appraisals
Authors: Eiser J. Richard , Shook Natalie J. , Fazio Russell H. 
Published: January 2007

AbstractProcesses of attitude learning were investigated through a game requiring discrimination between good and bad objects, where feedback about object valence (involving gain or loss) is contingent on approach. Previous research demonstrates a preponderance of false‐negative errors, with some good objects (‘learning asymmetry’) and most novel objects (‘generalization asymmetry’) being judged as bad, but provides no direct evidence concerning how participants appraise alternative strategies and their own performance. To compare alternative strategies, participants received advice, supposedly from a previous participant, that most objects were bad and should be avoided, or good and should be approached. Learning and generalization asymmetries were replicated, especially among participants who followed the former (risk‐averse) advice. Additionally, participants' evaluations of their own game strategy were inversely related to amount of negative feedback (the number of bad objects approached), but unrelated to positive feedback (from good objects approached), pointing to the salience of negative information for self‐appraisals. Copyright © 2007 John Wiley & Sons, Ltd.
Biodegradation of benzo[a]pyrene with immobilized laccase: Genotoxicity of the products in HaCat and A3 cells
Authors: Hu Xiaoke , Zhang Yi , Zhao Xueheng , Hwang Huey‐Min 
Published: January 2007

AbstractBenzo[a]pyrene (BaP) is listed as a priority pollutant by the U.S. Environmental Protection Agency because it is one of the most potent carcinogens of all known polycyclic aromatic hydrocarbons (PAHs). The biodegradation of BaP is of interest as a means for mitigating its effects in polluted ecosystems. In the present study, BaP was oxidized with laccase from Trametes versicolor, which was immobilized on functionalized kaolinite particles, and the cytotoxicity and genotoxicity of BaP and its degradation intermediates were measured in human HaCaT keratinocytes and A3 T lymphocytes. Cytotoxicity was assessed by fluorescein diacetate (FDA) uptake, while the alkaline Comet assay measured genotoxicity, using tail moment, tail DNA content, and tail length as metrics for DNA damage. On the basis of first‐order reaction kinetics, the half life (t1/2) for the oxidization of BaP by immobilized laccase was 58.5 hr. After 87 hr of oxidation, 20 μM of BaP had decreased to 9.6 μM. HPLC analysis identified 1,6‐benzo[a]pyrene quinone (1,6‐BaQ), 3,6‐benzo[a]pyrene quinone (3,6‐BaQ), and 6,12‐benzo[a]pyrene quinone (6,12‐BaQ) among the oxidation products. Most treatments of HaCaT cells and A3 lymphocytes with BaP or its quinone intermediates resulted in significant decreases in viability (P < 0.05); dose‐dependent decreases in cell viability were detected at concentrations of 0.1, 1, and 5 μM, but none of these treatments resulted in decreases of >30%. While treatment of HaCaT cells with as little as 0.1 μM 6,12‐BaQ caused significant DNA damage, DNA damage was detected in HaCaT cells only with 1 and 5 μM 1,6‐BaQ and 3,6‐BaQ, and 5 μM BaP. In Comet assays conducted with A3 lymphocytes, all three quinone intermediates caused significant increase in tail DNA content at 1 and 5 μM. The results indicate that immobilized laccase is capable of degrading BaP, but several of those biodegradation products produce significant levels of DNA damage in human cells. Environ. Mol. Mutagen., 2007. © 2007 Wiley‐Liss, Inc.
An optimized Schwarz method with two‐sided Robin transmission conditions for the Helmholtz equation
Authors: Gander M. J. , Halpern L. , Magoulès F. 
Published: January 2007

AbstractOptimized Schwarz methods are working like classical Schwarz methods, but they are exchanging physically more valuable information between subdomains and hence have better convergence behaviour. The new transmission conditions include also derivative information, not just function values, and optimized Schwarz methods can be used without overlap. In this paper, we present a new optimized Schwarz method without overlap in the 2d case, which uses a different Robin condition for neighbouring subdomains at their common interface, and which we call two‐sided Robin condition. We optimize the parameters in the Robin conditions and show that for a fixed frequency an asymptotic convergence factor of 1 – O(h1/4) in the mesh parameter h can be achieved. If the frequency is related to the mesh parameter h, h = O(1/ωγ) for γ⩾1, then the optimized asymptotic convergence factor is 1 – O(ω(1–2γ)/8). We illustrate our analysis with 2d numerical experiments. Copyright © 2007 John Wiley & Sons, Ltd.