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Structural Differences (structural + difference)
Kinds of Structural Differences Selected AbstractsStructural Differences in the Umbilical Vein Wall after Full-Term and Pre-term DeliveryANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2009M. Bagyánszki Summary With the exception of its most proximal segment, the human umbilical cord lacks innervation. It might be expected, therefore, that a paracrine effect through the direct contact between the smooth muscle cells and the endothelium may be particularly important in the control of the fetoplacental circulation. In this study, electron microscopy and immunohistochemistry were applied to examine umbilical veins immediately after full-term and pre-term delivery. The smooth muscle cells in the upper layer of the tunica media exhibited long, foot-like processes with c-kit immunoreactivity. In the umbilical vein of full-term neonates more than 50% of these cell processes display a normal ultrastructure and they were closely associated with the lamina elastica interna. Whereas in pre-term infants more than 60% of these cell processes exhibit signs of severe shrinkage and detachedness from the lamina elastica interna. At the same time, the high level of immunoreactivity of the endothelial cells as regards the proapoptotic gene product Bax in pre-term infants is indicative of an enhanced apoptotic process in these cells. [source] Structural Correlates of Functional Language Dominance: A Voxel-Based Morphometry StudyJOURNAL OF NEUROIMAGING, Issue 2 2010Andreas Jansen PhD ABSTRACT BACKGROUND AND PURPOSE The goal of this study was to explore the structural correlates of functional language dominance by directly comparing the brain morphology of healthy subjects with left- and right-hemisphere language dominance. METHODS Twenty participants were selected based on their language dominance from a cohort of subjects with known language lateralization. Structural differences between both groups were assessed by voxel-based morphometry, a technique that automatically identifies differences in the local gray matter volume between groups using high-resolution T1-weighted magnetic resonance images. RESULTS The main findings can be summarized as follows: (1) Subjects with right-hemisphere language dominance had significantly larger gray matter volume in the right hippocampus than subjects with left-hemisphere language dominance. (2) Leftward structural asymmetries in the posterior superior temporal cortex, including the planum temporale (PT), were observed in both groups. CONCLUSIONS Our study does not support the still prevalent view that asymmetries of the PT are related in a direct way to functional language lateralization. The structural differences found in the hippocampus underline the importance of the medial temporal lobe in the neural language network. They are discussed in the context of recent findings attributing a critical role of the hippocampus in the development of language lateralization. [source] Titanium-Catalyzed Norbornene Oligomerization.MACROMOLECULAR RAPID COMMUNICATIONS, Issue 22 20063- exo -Disyndiotactic Structure, Isolation of a Crystalline Heptamer with a Abstract Summary: Norbornene (NB) was oligomerized at 0,°C using AlEt2Cl-TiCl4 at a monomer/titanium molar ratio of about 11. The oligomerization product consists of a fraction soluble in diethyl ether, amorphous by X-ray examination, and of a crystalline fraction, insoluble in diethyl ether. The crystalline fraction was shown by powder X-ray diffraction to consist of a NB heptamer. Single-crystal X-ray analysis indicated that the heptamer had a stereoregular 2,3- exo -disyndiotactic structure. The heptamer adopts a strained, highly irregular, folded conformation in the crystalline state. Structural differences with respect to NB oligomers obtained with zirconocene catalysts are discussed. A view of the molecular structure of the crystalline NB heptamer. [source] Structure of human brain fructose 1,6-(bis)phosphate aldolase: Linking isozyme structure with functionPROTEIN SCIENCE, Issue 12 2004Tracy L. Arakaki Abstract Fructose-1,6-(bis)phosphate aldolase is a ubiquitous enzyme that catalyzes the reversible aldol cleavage of fructose-1,6-(bis)phosphate and fructose 1-phosphate to dihydroxyacetone phosphate and either glyceral-dehyde-3-phosphate or glyceraldehyde, respectively. Vertebrate aldolases exist as three isozymes with different tissue distributions and kinetics: aldolase A (muscle and red blood cell), aldolase B (liver, kidney, and small intestine), and aldolase C (brain and neuronal tissue). The structures of human aldolases A and B are known and herein we report the first structure of the human aldolase C, solved by X-ray crystallography at 3.0 Å resolution. Structural differences between the isozymes were expected to account for isozyme-specific activity. However, the structures of isozymes A, B, and C are the same in their overall fold and active site structure. The subtle changes observed in active site residues Arg42, Lys146, and Arg303 are insufficient to completely account for the tissue-specific isozymic differences. Consequently, the structural analysis has been extended to the isozyme-specific residues (ISRs), those residues conserved among paralogs. A complete analysis of the ISRs in the context of this structure demonstrates that in several cases an amino acid residue that is conserved among aldolase C orthologs prevents an interaction that occurs in paralogs. In addition, the structure confirms the clustering of ISRs into discrete patches on the surface and reveals the existence in aldolase C of a patch of electronegative residues localized near the C terminus. Together, these structural changes highlight the differences required for the tissue and kinetic specificity among aldolase isozymes. [source] Functional significance of genetic variation underlying limb bone diaphyseal structureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Ian J. Wallace Abstract Limb bone diaphyseal structure is frequently used to infer hominin activity levels from skeletal remains, an approach based on the well-documented ability of bone to adjust to its loading environment during life. However, diaphyseal structure is also determined in part by genetic factors. This study investigates the possibility that genetic variation underlying diaphyseal structure is influenced by the activity levels of ancestral populations and might also have functional significance in an evolutionary context. We adopted an experimental evolution approach and tested for differences in femoral diaphyseal structure in 1-week-old mice from a line that had been artificially selected (45 generations) for high voluntary wheel running and non-selected controls. As adults, selected mice are significantly more active on wheels and in home cages, and have thicker diaphyses. Structural differences at 1 week can be assumed to primarily reflect the effects of selective breeding rather than direct mechanical stimuli, given that the onset of locomotion in mice is shortly after Day 7. We hypothesized that if genetically determined diaphyseal structure reflects the activity patterns of members of a lineage, then selected animals will have relatively larger diaphyseal dimensions at 1 week compared to controls. The results provide strong support for this hypothesis and suggest that limb bone cross sections may not always only reflect the activity levels of particular fossil individuals, but also convey an evolutionary signal providing information about hominin activity in the past. Am J Phys Anthropol 143:21,30, 2010. © 2010 Wiley-Liss, Inc. [source] Habitual throwing and swimming correspond with upper limb diaphyseal strength and shape in modern human athletesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Colin N. Shaw Abstract Variation in upper limb long bone cross-sectional properties may reflect a phenotypically plastic response to habitual loading patterns. Structural differences between limb bones have often been used to infer past behavior from hominin remains; however, few studies have examined direct relationships between behavioral differences and bone structure in humans. To help address this, cross-sectional images (50% length) of the humeri and ulnae of university varsity-level swimmers, cricketers, and controls were captured using peripheral quantitative computed tomography. High levels of humeral robusticity were found in the dominant arms of cricketers, and bilaterally among swimmers, whereas the most gracile humeri were found in both arms of controls, and the nondominant arms of cricketers. In addition, the dominant humeri of cricketers were more circular than controls. The highest levels of ulnar robusticity were also found in the dominant arm of cricketers, and bilaterally amongst swimmers. Bilateral asymmetry in humeral rigidity among cricketers was greater than swimmers and controls, while asymmetry for ulnar rigidity was greater in cricketers than controls. The results suggest that more mechanically loaded upper limb elements,,unilaterally or bilaterally,,are strengthened relative to less mechanically loaded elements, and that differences in mechanical loading may have a more significant effect on proximal compared to distal limb segments. The more circular humerus in the dominant arm in cricketers may be an adaptation to torsional strain associated with throwing activities. The reported correspondence between habitual activity patterns and upper limb diaphyseal properties may inform future behavioral interpretations involving hominin skeletal remains. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] 2-Bromo-6-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine, a new unexpected bifunctional building block for combinatorial chemistryACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2003Jana Sopková-de Oliveira Santos The first reported structure of a pyridin-2-ylboron derivative, viz. the title compound, C11H15BBrNO2, (I), is compared with its regioisomer 2-bromo-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine, (II) [Sopková-de Oliveira Santos, Lancelot, Bouillon & Rault (2003). Acta Cryst. C59, o111o113]. Structural differences are observed, firstly in the orientation of the dioxaborolane ring with respect to the pyridine ring and secondly in the bond angles of the BO2 group. These differences do not explain the experimentally observed differences in chemical reactivity between (I) and (II) but do confirm the relatively lower stability of (I). However, ab initio calculations of the HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), based on the known crystal structures of the two compounds, show different distributions, which correspond to the differences observed during chemical reactions. [source] No change in the structure of the brain in migraine: a voxel-based morphometric studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2003M. S. Matharu Migraine is a common, disabling form of primary neurovascular headache. For most of the twentieth century it was regarded as a vascular headache whose primary pathophysiology lay in the cranial vasculature. Functional brain imaging using positron emission tomography has demonstrated activation of the rostral brain stem in acute migraine. Voxel-based morphometry is a new fully automated whole brain technique that is sensitive to subtle macroscopic and mesoscopic structural differences between groups of subjects. In this study 11 patients suffering from migraine with aura (10 females, one male: 23,52 years, mean 31); 11 controls (10 females, one male: 23,52, mean 31); 17 patients with migraine without aura (16 females, one male: 24,57, mean 34); 17 controls (16 females, one male: 24,57, mean 34) were imaged with high resolution volumetric magnetic resonance imaging. There was no significant difference in global grey or white matter volumes between either patients with migraine and controls, or patients with aura and without aura. This study did not show any global or regional macroscopic structural difference between patients with migraine and controls, with migraine sufferers taken as homogenous groups. If structural changes are to be found, other methods of phenotyping migraine, such as by genotype or perhaps treatment response, may be required to resolve completely whether there is some subtle structural change in the brain of patients with migraine. [source] The Impact of Polymer Regioregularity on Charge Transport and Efficiency of P3HT:PCBM Photovoltaic DevicesADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Ralf Mauer Abstract The charge transport in pristine poly(3-hexylthiophene) (P3HT) films and in photovoltaic blends of P3HT with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) is investigated to study the influence of charge-carrier transport on photovoltaic efficiency. The field- and temperature dependence of the charge-carrier mobility in P3HT of three different regioregularities, namely, regiorandom, regioregular with medium regioregularity, and regioregular with very high regioregularity are investigated by the time-of-flight technique. While medium and very high regioregularity polymers show the typical absorption features of ordered lamellar structures of P3HT in the solid state even without previous annealing, films of regiorandom P3HT are very disordered as indicated by their broad and featureless absorption. This structural difference in the solid state coincides with partially non-dispersive transport and hole mobilities µh of around 10,4 and 10,5,cm2 V,1 s,1 for the high and medium regioregularity P3HT, respectively, and a slow and dispersive charge transport for the regiorandom P3HT. Upon blending the regioregular polymers with PCBM, the hole mobilities are typically reduced by one order of magnitude, but they do not significantly change upon additional post-spincasting annealing. Only in the case of P3HT with high regioregularity are the electron mobilities similar to the hole mobilities and the charge transport is, thus, balanced. Nonetheless, devices prepared from both materials exhibit similar power conversion efficiencies of 2.5%, indicating that very high regioregularity may not substantially improve order and charge-carrier transport in P3HT:PCBM and does not lead to significant improvements in the power-conversion efficiency of photovoltaic devices. [source] Enhanced compatibility of PA6/POE blends by POE- g -MAH prepared through ultrasound-assisted extrusionJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Tingting Xie Abstract The effects of POE- g -MAH, prepared through different methods, on morphology and properties of PA6/POE/POE- g -MAH blends are summarized in this article. The grafting degree of POE- g -MAH can be increased through the ultrasound-assisted extrusion. Experimental results showed that the addition of POE- g -MAH can increase the mechanical properties of the PA6/POE blend and decrease the particle size of POE dispersed phase in PA6 matrix due to the compatibilization by POE- g -MAH. The PA6/POE blend compatibilized by POE- g -MAH prepared through the ultrasound-assisted extrusion has smaller particle size of POE dispersed phase and higher notched Izod impact strength than that by POE- g -MAH with similar grafting degree initiated only by peroxide. This result is ascribed to some anhydride rings attached to the chain terminus of POE due to ultrasound initiation. Rheological and Molau test results also showed enhanced compatibilization of POE- g -MAH prepared through the ultrasound-assisted extrusion on the PA6/POE blend due to a structural difference of POE- g -MAH. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Bis-8-hydroxyquinoline and bis-8-hydroxyquinaldine N -substituted amines: A single methyl group structural difference between the two heterocycles, which modulates the antiproliferative effectsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2010Sébastien Madonna The synthesis of a series of bis-8-hydroxyquinoline- and bis-8-hydroxyquinaldine-substituted N -benzyl or thiophenyl amines and their corresponding bis-8-hydroxyquinoline is reported. In vitro growth inhibitory effects of both series have been evaluated. It has been observed that analogs from the bis-8-hydroxyquinoline series exert nanomolar range activity, whereas the antiproliferative activity of the corresponding analogs from the bis-8-hydroxyquinaldine series was found to be drastically lower. Molecular docking and chemical,physical properties account for these observed growth inhibitory differences between the two series of analogs, which differ only by the presence of a methyl group at the 2 position of the heterocyclic ring. J. Heterocyclic Chem., (2010). [source] X-ray structural analysis of the ligand-recognition mechanism in the dual-affinity labeling of c-type lysozyme with 2,,3,-epoxypropyl ,-glycoside of N -acetyllactosamineJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2003Michiro Muraki Abstract In spite of the belonging to the same c-type lysozyme family, hen egg-white lysozyme (HEWL) was much less susceptible to the dual-affinity labeling with 2,,3,-epoxypropyl ,-glycoside of N -acetyllactosamine (Gal,1,4GlcNAc-Epo) than human lysozyme (HL). The three-dimensional structures of the HEWL labeled with single Gal,1,4GlcNAc-Epo and the Glu102-mutant HL labeled with double Gal,1,4GlcNAc-Epo were determined by X-ray crystallography at resolutions of 1.85 and 2.0,Å, respectively. The overall conformation and the interaction mode of the carbohydrate ligand part in the singly labeled HEWL and the doubly labeled Glu102-mutant HL were basically identical to those of the correspondingly labeled wild-type HL with minor alterations in some stereochemical parameters. A detailed comparison of the structures revealed the key protein,carbohydrate and carbohydrate,carbohydrate interactions essential for the dual labeling. It was suggested that the difference in the efficiency of the dual labeling was caused by the structural difference between Gln104 in HL and Asn103 in HEWL. The relevance to our previous study and the carbohydrate,carbohydrate interaction on cell-surface membranes were discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Complete structure determination of the A chain of mistletoe lectin III from Viscum album L. ssp. albumJOURNAL OF PEPTIDE SCIENCE, Issue 3 2004Roland Wacker Abstract The complete primary structure of the A chain of mistletoe lectin III (ML3A), a type II ribosome-inactivating protein, was determined using proteolytic digests of ML3A, HPLC separation of the peptides, Edman degration and MALDI-MS. Based on our results, ML3A consists of 254 amino acid residues, showing a high homology to the A chain of isolectin ML1 with only 24 amino acid residue exchanges. A striking important structural difference compared with ML1A is the lack of the single N-glycosylation site in ML3A due to an amino acid exchange at position 112 (ML1A: N112GS,ML3A: T112GS). The alignment of ML3A with the A chains of ML1, isoabrins, ricin D, Ricinus communis agglutinin and three lectins, identified from the Korean mistletoe Viscum album ssp. coloratum, demonstrates the rigid conservation of all amino acid residues, responsible for the RNA-N-glycosidase activity as reported for ricin D. In addition, the fully determined primary structure of ML3A will give further information about the biological mechanism of mistletoe lectin therapy. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Solid-state NMR studies of the molecular structure of TaxolMAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2006Yu Ho Abstract Solid-state 13C{1H} cross-polarization/magic angle spinning spectroscopy (CP/MAS) has been utilized to extract the molecular structure information of Taxol, which is an anti-tumor therapeutic medicine extracted from the yew bark. The 13C signals have chemical shift values quite consistent with those measured in solution phase, and the overall chemical shift range is over 200 ppm. Notably, most of the 13C resonances of the taxane ring have two clearly resolved spectral components except the resonance peaks of C-15, C-16 and C-17, which are located at the central part of the taxane ring. On the basis of our NMR data, we propose that these doublets originate from two slightly different molecular conformations of the taxane ring and still the central part of the ring remains structurally similar. Furthermore, it is demonstrated that the 13C chemical shift difference deduced from the doublet splittings can serve as a direct measure of the structural difference between the two conformations, which could possibly correlate with the anti-tumor activity of Taxol. Copyright © 2006 John Wiley & Sons, Ltd. [source] Lower critical solution temperatures of thermo-responsive poly(N -isopropylacrylamide) copolymers with racemate or single enantiomer groupsPOLYMER INTERNATIONAL, Issue 2 2009Peng-Fei Li Abstract BACKGROUND: Thermo-responsive copolymers with racemate or single enantiomer groups are attracting increasing attention due to their fascinating functional properties and potential applications. However, there is a lack of systematic information about the lower critical solution temperature (LCST) of poly(N -isopropylacrylamide)-based thermo-responsive chiral recognition systems. In this study, a series of thermo-responsive chiral recognition copolymers, poly[(N -isopropylacrylamide)- co -(N -(S)- sec -butylacrylamide)] (PN- S -B) and poly[(N -isopropylacrylamide)- co -(N -(R,S)- sec -butylacrylamide)] (PN- R,S -B), with different molar compositions, were prepared. The effects of heating and cooling processes, optical activity and amount of chiral recognition groups in the copolymers on the LCSTs of the prepared copolymers were systematically studied. RESULTS: LCST hysteresis phenomena are found in the phase transition processes of PN- S -B and PN- R,S -B copolymers in a heating and cooling cycle. The LCSTs of PN- S -B and PN- R,S -B during the heating process are higher than those during the cooling process. With similar molar ratios of N -isopropylacrylamide groups in the copolymers, the LCST of the copolymer containing a single enantiomer (PN- S -B) is lower than that of the copolymer containing racemate (PN- R,S -B) due to the steric structural difference. The LCSTs of PN- R,S -B copolymers are in inverse proportion to the molar contents of the hydrophobic R,S -B moieties in these copolymers. CONCLUSION: The results provide valuable guidance for designing and fabricating thermo-responsive chiral recognition systems with desired LCSTs. Copyright © 2008 Society of Chemical Industry [source] Phase transition of triclinic hen egg-white lysozyme crystal associated with sodium bindingACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2004Kazuaki Harata A triclinic crystal of hen egg-white lysozyme obtained from a D2O solution at 313,K was transformed into a new triclinic crystal by slow release of solvent under a temperature-regulated nitrogen-gas stream. The progress of the transition was monitored by X-ray diffraction. The transition started with the appearance of strong diffuse streaks. The diffraction spots gradually fused and faded with the emergence of diffraction from the new lattice; the scattering power of the crystal fell to a resolution of 1.5,Å from the initial 0.9,Å resolution. At the end of the transition, the diffuse streaks disappeared and the scattering power recovered to 1.1,Å resolution. The transformed crystal contained two independent molecules and the solvent content had decreased to 18% from the 32% solvent content of the native crystal. The structure was determined at 1.1,Å resolution and compared with the native structure refined at the same resolution. The backbone structures of the two molecules in the transformed crystal were superimposed on the native structure with root-mean-square deviations of 0.71 and 0.96,Å. A prominent structural difference was observed in the loop region of residues Ser60,Leu75. In the native crystal, a water molecule located at the centre of this helical loop forms hydrogen bonds to main-chain peptide groups. In the transformed crystal, this water molecule is replaced by a sodium ion with octahedral coordination that involves water molecules and a nitrate ion. The peptide group connecting Arg73 and Asn74 is rotated by 180° so that the CO group of Arg73 can coordinate to the sodium ion. The change in the X-ray diffraction pattern during the phase transition suggests that the transition proceeds at the microcrystal level. A mechanism is proposed for the crystal transformation. [source] Avian haemoglobins and structural basis of high affinity for oxygen: structure of bar-headed goose aquomet haemoglobinACTA CRYSTALLOGRAPHICA SECTION D, Issue 6 2001Xiao-Zhou Liu Haemoglobin from the bar-headed goose (Anser indicus) has higher oxygen affinity than that from its lowland relatives such as greylag goose (A. anser). The crystal structure of bar-headed goose aquomet haemoglobin was determined at 2.3,Å resolution and compared with the structures of the goose oxy, human, horse and other avian haemoglobins and the sequences of other avian haemoglobins. Four amino-acid residues differ between greylag goose and bar-headed goose haemoglobins, among which Ala,119 and Asp,125 in bar-headed goose haemoglobin reduces the contacts between the ,1 and ,1 subunits compared with Pro and Glu, respectively, and therefore may increase the oxygen affinity by loosening the ,1,1 interface. Compared with human oxy haemoglobin, the relative orientation of two ,, dimers in the bar-headed goose aquomet and oxy Hbs are rotated by about 4°, indicating a unique quaternary structural difference from the typical R state. This new `RH' state is probably correlated with the higher oxygen affinity of bar-headed goose haemoglobin. [source] A systematic case study on using NMR models for molecular replacement: p53 tetramerization domain revisitedACTA CRYSTALLOGRAPHICA SECTION D, Issue 12 2000Yu Wai Chen Molecular replacement using search models derived from nuclear magnetic resonance (NMR) spectroscopy has often proved problematic. It has been known for some time that the overall differences in atomic positions (r.m.s.d.) between the crystalline and the solution states of the same protein are of the order of 1,2,Å and approach the limit of molecular replacement. In most cases, this structural difference is a result of calculating the NMR structure with insufficient data, yielding an NMR structure of limited accuracy. A systematic case study was performed to investigate the use of NMR models for molecular replacement on the p53 tetramerization domain: NMR search models of varying degrees of accuracy were employed to solve phases for the 1.5,Å X-ray diffraction data. An approximate correlation was found between the accuracy of the NMR search model and the clarity and quality of the molecular-replacement solution. It was found that ensemble models perform better than single averaged models and have a larger tolerance in model inaccuracy. Also, distance-derived B factors can improve the performance of single models. [source] Structure of human protein kinase CK2,2 with a potent indazole-derivative inhibitorACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2009Tetsuko Nakaniwa Casein kinase 2 (CK2) is a serine/threonine kinase that functions as a heterotetramer composed of two catalytic subunits (CK2,1 or CK2,2) and two regulatory subunits (CK2,). The two isozymes CK2,1 and CK2,2 play distinguishable roles in healthy subjects and in patients with diseases such as cancer, respectively. In order to develop novel CK2,1-selective inhibitors, the crystal structure of human CK2,2 (hCK2,2) complexed with a potent CK2, inhibitor which binds to the active site of hCK2,2 was determined and compared with that of human CK2,1. While the two isozymes exhibited a high similarity with regard to the active site, the largest structural difference between the isoforms occurred in the ,4,,5 loop responsible for the CK2,,CK2, interface. The top of the N-terminal segment interacted with the ,4,,5 loop via a hydrogen bond in hCK2,2 but not in hCK2,1. Thus, the CK2,,CK2, interface is a likely target candidate for the production of selective CK2,1 inhibitors. [source] New potent and selective inhibitors of anandamide reuptake with antispastic activity in a mouse model of multiple sclerosisBRITISH JOURNAL OF PHARMACOLOGY, Issue 1 2006Alessia Ligresti We previously reported that the compound O-2093 is a selective inhibitor of the reuptake of the endocannabinoid anandamide (AEA). We have now re-examined the activity of O-2093 in vivo and synthesized four structural analogs (O-2247, O-2248, O-3246, and O-3262), whose activity was assessed in: (a) binding assays carried out with membranes from cells overexpressing the human CB1 and CB2 receptors; (b) assays of transient receptor potential of the vanilloid type-1 (TRPV1) channel functional activity (measurement of [Ca2+]i); (c) [14C]AEA cellular uptake and hydrolysis assays in rat basophilic leukaemia (RBL-2H3) cells; (d) the mouse ,tetrad' tests (analgesia on a hot plate, immobility on a ,ring', rectal hypothermia and hypolocomotion in an open field); and (e) the limb spasticity test in chronic relapsing experimental allergic encephalomyelitis (CREAE) mice, a model of multiple sclerosis (MS). O-2093, either synthesized by us or commercially available, was inactive in the ,tetrad' up to a 20 mg kg,1 dose (i.v.). Like O-2093, the other four compounds exhibited low affinity in CB1 (Ki from 1.3 to >10 ,M) and CB2 binding assays (1.3 Rational Design, Synthesis, and Optical Properties of Film-Forming, Near-Infrared Absorbing, and Fluorescent Chromophores with Multidonors and Large Heterocyclic AcceptorsCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2009Min Luo Abstract A new series of film-forming, low-bandgap chromophores (1,a,b and 2,a,b) were rationally designed with aid of a computational study, and then synthesized and characterized. To realize absorption and emission above the 1000,nm wavelength, the molecular design focuses on lowering the LUMO level by fusing common heterocyclic units into a large conjugated core that acts an electron acceptor and increasing the charge transfer by attaching the multiple electron-donating groups at the appropriate positions of the acceptor core. The chromophores have bandgap levels of 1.27,0.71,eV, and accordingly absorb at 746,1003,nm and emit at 1035,1290,nm in solution. By design, the relatively high molecular weight (up to 2400,g,mol,1) and non-coplanar structure allow these near-infrared (NIR) chromophores to be readily spin-coated as uniform thin films and doped with other organic semiconductors for potential device applications. Doping with [6,6]-phenyl-C61 butyric acid methyl ester leads to a red shift in the absorption only for 1,a and 2,a. An interesting NIR electrochromism was found for 2,a, with absorption being turned on at 1034,nm when electrochemically switched (at 1000,mV) from its neutral state to a radical cation state. Furthermore, a large Stokes shift (256,318,nm) is also unique for this multidonor,acceptor type of chromophore, indicating a significant structural difference between the ground state and the excited state. Photoluminescence of the film of 2,a was further probed at variable temperatures and the results strongly suggest that the restriction of bond rotations certainly helps to diminish non-radiative decay and thus enhance the luminescence of these large chromophores. [source] Structure determination of chiral sulfoxide in diastereomeric bicalutamide derivativesCHIRALITY, Issue 6 2009Wei Li Abstract We report on the synthesis and investigation of two diastereomers (5a and 5b) of a new bicalutamide analog with an asymmetric carbon atom and a chiral sulfoxide group. These bicalutamide analogs are novel androgen receptor antagonists with biological activities that depend significantly on the configuration of their stereogenic centers. We determined the absolute configuration at the SO center by combining X-ray and NMR measurements with quantum chemical calculations. Since 5a and 5b failed to yield satisfactory crystals for X-ray crystal structure determination, analogs 6a and 6b differing in only one remote functional group relative to the chiral sulfoxide were synthesized, which yielded satisfactory crystals. X-ray structure determination of 6a and 6b provided the absolute configuration at the chiral sulfoxide. Since the structural difference between 5 and 6 is remote from the chiral sulfoxide, the structural assignment was extended from the diastereomers of 6 to those of 5 provisionally. These assignments were verified with the help of measured and DFT-calculated proton and carbon NMR chemical shifts. Chirality, 2008. © 2009 Wiley-Liss, Inc. [source] Comparing Mutual Fund Governance and Corporate GovernanceCORPORATE GOVERNANCE, Issue 5 2006Robert F. Radin Governance of public corporations in the United States has operated under the agency model with regulatory strengthening since the passage of Sarbanes-Oxley legislation. With this foundation in place, boards are empowered to utilise their power and influence and can effectively monitor the actions of management, intervening where necessary. In effect, the rules of engagement embodied in the structure and the law guide interactions and empowerment. The governance model of the mutual funds industry, representing over 8 trillion dollars, is often viewed as a mirror of the corporate world, but upon closer analysis is found to have significant structural differences that dilute the authority of directors. The two models are compared and analysed with recommendations made to strengthen the oversight of mutual funds. [source] Universal method for synthesis of artificial gel antibodies by the imprinting approach combined with a unique electrophoresis technique for detection of minute structural differences of proteins, viruses, and cells (bacteria).ELECTROPHORESIS, Issue 23 2006III: Gel antibodies against cells (bacteria) Abstract Artificial antibodies in the form of gel granules were synthesized from the monomers acrylamide and N,N'-methylenebisacrylamide by the imprinting method in the presence of Echerichia coli bacteria as template. The electrophoretic migration velocities of the gel antibodies (i),saturated with the antigen (Escherichia,coli MRE-600), (ii),freed of the antigen, and (iii),resaturated with bacteria, were determinated by electrophoresis in a rotating narrow-bore tube of 245,mm length and the 2.5 and 9.6,mm inner and outer diameters, respectively. Removal of bacteria from the gel antibodies was made by treatment with enzymes, followed by washing with SDS and buffer. Gel granules becoming charged by adsorption of bacteria move in an electrical field. We obtained a significant selectivity of gel antibodies for E.,coli MRE-600, since the granules did not interact with Lactococcus lactis; and when E.,coli BL21 bacteria were added to the gels selective for E.,coli MRE-600, a significant difference in the migration rate of the complexes formed with the two strains was observed indicating the ability of differentiation between the two strains. The gel antibodies can be used repeatedly. The new imprinting method for the synthesis of artificial gel antibodies against bioparticles described herein, and the classical electrophoretic analysis technique employed, thus represent , when combined , a new approach to distinguish between different types and strains of bacteria. The application area can certainly be extended to cover other classes of cells. [source] EU energy-intensive industries and emission trading: losers becoming winners?ENVIRONMENTAL POLICY AND GOVERNANCE, Issue 5 2009Jorgen Wettestad Abstract The EU Emissions Trading System (ETS) initially treated power producers and energy-intensive industries similarly, despite clear structural differences between these industries regarding e.g. pass-through of costs. Hence, the energy-intensive industries could be seen as losing out in the internal distribution. In the January 2008 proposal for a reformed ETS post-2012, a differentiated system was proposed where the energy-intensive industries would come out relatively much better. Why is this? Although power producers still have a dominant position in the system, the increasing consensus about windfall profits has weakened their standing. Conversely, increasing attention to such profits and not least the possibility of global carbon leakage has strengthened the case of energy-intensive industries at both national and EU levels. These industries have become more active in EU processes and somewhat better organized. Finally, growing fear of lax global climate policies has strengthened the case of these industries further. Copyright © 2009 John Wiley & Sons, Ltd and ERP Environment. [source] Persistence of Alarm-Call Behaviour in the Absence of Predators: A Comparison Between Wild and Captive-Born Meerkats (Suricata Suricatta)ETHOLOGY, Issue 11 2007Linda I. Hollén Performing correct anti-predator behaviour is crucial for prey to survive. But, are such abilities lost in species or populations living in predator-free environments? How individuals respond to the loss of predators has been shown to depend on factors such as the degree to which anti-predator behaviour relies on experience, the type of cues evoking the behaviour, the cost of expressing the behaviour and the number of generations under which relaxed selection has taken place. Here we investigated whether captive-born populations of meerkats (Suricata suricatta) used the same repertoire of alarm calls previously documented in wild populations and whether captive animals, as wild ones, could recognize potential predators through olfactory cues. We found that all alarm calls that have been documented in the wild also occurred in captivity and were given in broadly similar contexts. Furthermore, without prior experience of odours from predators, captive meerkats seemed to distinguish between faeces of potential predators (carnivores) and non-predators (herbivores). Despite slight structural differences, the alarm calls given in response to the faeces largely resembled those recorded in similar contexts in the wild. These results from captive populations suggest that direct, physical interaction with predators is not necessary for meerkats to perform correct anti-predator behaviour in terms of alarm-call usage and olfactory predator recognition. Such behaviour may have been retained in captivity because relatively little experience seems necessary for correct performance in the wild and/or because of the recency of relaxed selection on these populations. [source] Variation in Vocal Performance in the Songs of a Wood-Warbler: Evidence for the Function of Distinct Singing ModesETHOLOGY, Issue 7 2004Martin D. Beebee Male North American wood-warblers (family Parulidae) subdivide their song repertoires into two different categories, or modes, of singing (first and second category songs). These two modes are thought to be specialized for interacting with females and males, although the data are inconclusive. I conducted an acoustic analysis of the song types used by yellow warblers (Dendroica petechia) for type I (first category) and type II (second category) singing to ask whether there are consistent structural differences between them which could provide insight into how they might function as separate signals. I found that type I songs are performed closer to the upper boundary of a song performance limit, measured in terms of the difficulty of production, compared with type II songs. By contrast, the performance of specific song types did not depend on whether they were used for type I singing vs. type II singing by different males. In addition, type I songs had a greater amplitude increase across the first two syllables compared with type II songs. There was no relationship between the performance of type I or type II songs and male condition. These results suggest that wood-warblers might subdivide their song repertoire into distinct categories to highlight the relative vocal performance of their songs. [source] Towards Cationic Gallium Derivatives: Metallacycles from the Reactions of Organogallium Compounds with Tetraorganodichalcogenoimidodiphosphinates and a New N -(Diphenylthiophosphinyl)thioureato LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2004Virginia Montiel-Palma Abstract The organometallic complexes of general formulae [Me2Ga{,2 - E,E, -[R2P(E)NP(E,)R,2]}] [R = R, = Ph, E = E, = O (1); R = R, = Ph, E = E, = S (2); R = R, = Ph, E = E, = Se (3); R = R, = Ph, E = O, E, = S (4); R = Me, R, = Ph, E = S, E, = O (5)] and [Me2Ga{,2 - S,S, -[Ph2P(S)NC(S)(C9H10N)]}] (6) were obtained by facile methane elimination reactions from GaMe3 and the acidic ligands L1H [(XPPh2)2NH (X = O, S, Se), (OPPh2)(SPPh2)NH, and (OPMe2)(SPPh2)NH] and L2H [Ph2P(S)NHC(S)(C9H10N)] in toluene. Replacement of one phosphorus atom by a carbon atom in the ligand skeleton of L1H gave the new ligand L2H, which, upon reaction with GaMe3, gave compound 6, which shows no significant structural differences with respect to 1,5. Therefore, L2H does not induce partial planarity in the six-membered ring, indicating the necessity for replacing both phosphorus atoms of the ligand by carbon atoms, as in the ,-diketonate-type derivatives, in order to impose ring planarity. Thus, despite originating from a variety of ligands with differing donor atoms and substituents at the phosphorus atoms, all complexes show little structural differences. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] No change in the structure of the brain in migraine: a voxel-based morphometric studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2003M. S. Matharu Migraine is a common, disabling form of primary neurovascular headache. For most of the twentieth century it was regarded as a vascular headache whose primary pathophysiology lay in the cranial vasculature. Functional brain imaging using positron emission tomography has demonstrated activation of the rostral brain stem in acute migraine. Voxel-based morphometry is a new fully automated whole brain technique that is sensitive to subtle macroscopic and mesoscopic structural differences between groups of subjects. In this study 11 patients suffering from migraine with aura (10 females, one male: 23,52 years, mean 31); 11 controls (10 females, one male: 23,52, mean 31); 17 patients with migraine without aura (16 females, one male: 24,57, mean 34); 17 controls (16 females, one male: 24,57, mean 34) were imaged with high resolution volumetric magnetic resonance imaging. There was no significant difference in global grey or white matter volumes between either patients with migraine and controls, or patients with aura and without aura. This study did not show any global or regional macroscopic structural difference between patients with migraine and controls, with migraine sufferers taken as homogenous groups. If structural changes are to be found, other methods of phenotyping migraine, such as by genotype or perhaps treatment response, may be required to resolve completely whether there is some subtle structural change in the brain of patients with migraine. [source] ,-Conotoxin CVIB differentially inhibits native and recombinant N- and P/Q-type calcium channelsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2007Leonid Motin Abstract ,-Conotoxins are routinely used as selective inhibitors of different classes of voltage-gated calcium channels (VGCCs) in excitable cells. In the present study, we examined the potent N-type VGCC antagonist ,-conotoxin CVID and non-selective N- and P/Q-type antagonist CVIB for their ability to block native VGCCs in rat dorsal root ganglion (DRG) neurons and recombinant VGCCs expressed in Xenopus oocytes. ,-Conotoxins CVID and CVIB inhibited depolarization-activated whole-cell VGCC currents in DRG neurons with pIC50 values of 8.12 ± 0.05 and 7.64 ± 0.08, respectively. Inhibition of Ba2+ currents in DRG neurons by CVID (, 66% of total) appeared to be irreversible for >,30 min washout, whereas Ba2+ currents exhibited rapid recovery from block by CVIB (, 80% within 3 min). The recoverable component of the Ba2+ current inhibited by CVIB was mediated by the N-type VGCC, whereas the irreversibly blocked current (, 22% of total) was attributable to P/Q-type VGCCs. ,-Conotoxin CVIB reversibly inhibited Ba2+ currents mediated by N- (CaV2.2) and P/Q- (CaV2.1), but not R- (CaV2.3) type VGCCs expressed in Xenopus oocytes. The ,2,1 auxiliary subunit co-expressed with CaV2.2 and CaV2.1 reduced the sensitivity of VGCCs to CVIB but had no effect on reversibility of block. Determination of the NMR structure of CVIB identified structural differences to CVID that may underlie differences in selectivity of these closely related conotoxins. ,-Conotoxins CVIB and CVID may be useful as antagonists of N- and P/Q-type VGCCs, particularly in sensory neurons involved in processing primary nociceptive information. [source]
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