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Mediated
Selected AbstractsAlcohol Expectancies and Drinking Refusal Self-Efficacy Mediate the Association of Impulsivity With Alcohol MisuseALCOHOLISM, Issue 8 2010Matthew J. Gullo Background:, Recent work suggests that 2 biologically based traits convey risk for alcohol misuse: reward sensitivity/drive and (rash) impulsiveness. However, the cognitive mechanisms through which these traits convey risk are unclear. This study tested a model predicting that the risk conveyed by reward sensitivity is mediated by a learning bias for the reinforcing outcomes of alcohol consumption (i.e., positive alcohol expectancy). The model also proposed that the risk conveyed by rash impulsiveness (RI) is mediated by drinkers' perceived ability to resist alcohol (i.e., drinking refusal self-efficacy). Methods:, Study 1 tested the model in a sample of young adults (n = 342). Study 2 tested the model in a sample of treatment-seeking substance abusers (n = 121). All participants completed a battery of personality, cognitive, and alcohol use questionnaires and models were tested using structural equation modeling. Results:, In both studies, the hypothesized model was found to provide a good fit to the data, and a better fit than alternative models. In both young adults and treatment-seeking individuals, positive alcohol expectancy fully mediated the association between reward sensitivity and hazardous alcohol use. For treatment seekers, drinking refusal self-efficacy fully mediated the association between RI and hazardous drinking. However, there was partial mediation in the young adult sample. Furthermore, neither trait was directly associated with the other cognitive mediator. Conclusions:, The hypothesized model was confirmed on a large sample of young adults and replicated on a sample of treatment-seeking substance abusers. Taken together, these findings shed further light on the mechanisms through which an impulsive temperament may convey risk for alcohol misuse. [source] Necessary and Discretionary Activities in Knee Osteoarthritis: Do They Mediate the Pain,Depression Relationship?PAIN MEDICINE, Issue 5 2007Patricia A. Parmelee PhD ABSTRACT Objective., This study examined direct vs indirect associations of pain and physical function with depression in 369 older adults with osteoarthritis (OA) of the knee. A key focus was the distinction of functional disability in necessary tasks (basic and instrumental activities of daily living) from discretionary, leisure activities. Design., A naturalistic longitudinal study examined effects of demographic variables, indicators of arthritis status, general health, pain, and several measures of functional disability upon depressive symptoms at baseline and 1 year later. Setting and Patients., Participants with diagnosed knee OA were recruited from rheumatological and general geriatric outpatient clinics, as well as public service announcements. Outcome Measure., Depressive symptoms, measured with the Center for Epidemiologic Studies Depression scale. Results., At baseline, the relationships of depression with functional disability and activity limitation were wholly mediated by pain. In contrast, activity participation was independently linked with depression, even controlling health and demographic variables. A 1-year follow-up revealed that depressive symptoms increased with increasing health problems, and with reduction in activity participation over time. Having and retaining favorite pastimes were also associated with reduced depressive symptomatology at baseline and follow-up, respectively. Conclusions., These data highlight the disease-specific nature of paths among depression, pain, and disability, and the importance of considering discretionary as well as necessary activities in evaluating effects of pain upon quality of life. [source] Site-Directed Mutagenesis of Rice Serine Racemase: Evidence That Glu219 and Asp225 Mediate the Effects of Mg2+ on the ActivityCHEMISTRY & BIODIVERSITY, Issue 6 2010Yoshitaka Gogami Abstract We succeeded in constructing the Glu219Ala/Asp225Ala (i.e., E219A/D225A) serine racemase (SerR) by site-directed mutagenesis, and the effects of Mg2+ on the catalytic efficiency and the structure were compared between the E219A/D225A-SerR and the wild-type protein. This is the first example of a serine racemase whose amino acid residues in the Mg2+ -binding site were replaced with other amino acids by site-directed mutagenesis. Neither the serine racemase nor the dehydratase activities of the E219A/D225A-SerR were affected by the addition of Mg2+, and Glu219 and Asp225 of the SerR are the essential amino acid residues for Mg2+ to affect both kinds of enzyme activities. Therefore, Glu219 and Asp225 mediate the effects of Mg2+ on the activity and are important for the SerR to form the Mg2+ -binding site. Judging from the difference of the Keq values between the E219A/D225A-SerR and the SerR, Mg2+ might affect the equilibrium states in the racemase reaction. The fluorescence quenching analysis of the E219A/D225A-SerR showed that Mg2+ bound to Glu219 and Asp225 of the SerR probably causes a conformational change in the ternary structure of the SerR. [source] Diastereoselective Reactions of the Tiglic Acid Functionality Mediated by Oxazolidine Chiral Auxiliaries: A Mechanistic Comparison of DMD andm -CPBA Epoxidations versus Singlet Oxygen and PTAD Ene ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2005Aurelia Pastor Abstract 2,2-Dimethyloxazolidines have been utilized as chiral auxiliaries for the diastereoselective functionalization of the optically active tiglic acid derivatives (S)- 1 by means of epoxidation with DMD or m -CPBA and ene reactions with 1O2 or PTAD. In the DMD and m -CPBA epoxidations, high diastereoselectivities but opposite senses of diastereomer selection were observed. In contrast, the stereochemistry of the 1O2 and PTAD ene reactions depended on the size of the attacking enophile: whereas essentially perfect diastereoselectivity was obtained with PTAD, much lower stereoselection was observed with 1O2. The stereochemical results for the DMD and m -CPBA epoxidations and the PTAD ene reaction are explained in terms of the energy differences for the corresponding diastereomeric transition states, dictated by steric and electronic effects. The PTAD ene reaction for these tiglic acids (S)- 1 provides, after removal of the chiral auxiliaries, an attractive synthetic route for optically active ,-amino acid derivatives.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Dual Stimuli-Responsive Supramolecular Polypeptide-Based Hydrogel and Reverse Micellar Hydrogel Mediated by Host,Guest ChemistryADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Yi Chen Abstract Versatile strategies are currently being discovered for the fabrication of synthetic polypeptide-based hybrid hydrogels, which have potential applications in polymer therapeutics and regenerative medicine. Herein, a new concept,the reverse micellar hydrogel,is introduced, and a versatile strategy is provided for fabricating supramolecular polypeptide-based normal micellar hydrogel and reverse micellar hydrogels from the same polypeptide-based copolymer via the cooperation of host,guest chemistry and hydrogen-bonding interactions. The supramolecular hydrogels are thoroughly characterized, and a mechanism for their self-assembly is proposed. These hydrogels can respond to dual stimuli,temperature and pH,and their mechanical and controlled drug-release properties can be tuned by the copolymer topology and the polypeptide composition. The reverse micellar hydrogel can load 10% of the anticancer drug doxorubicin hydrochloride (DOX) and sustain DOX release for 45 days, indicating that it could be useful as an injectable drug delivery system. [source] Theoretical Studies on ortho -Oxidation of Phenols with Dioxygen Mediated by Dicopper Complex: Hints for a Catalyst with the Phenolase Activity of TyrosinaseADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4-5 2007Hiroshi Naka Abstract Theoretical studies on the chemo- and regioselective ortho -oxidation reaction of phenols mediated by a biomimetic (,,,2:,2peroxo)dicopper(II) complex were performed using unrestricted hybrid density functional theory (UB3LYP) calculations, with the aim of providing a guide for the development of new bio-inspired catalysts with the phenolase activity of tyrosinase. Energetic, structural, and electronic analyses suggested the involvement of a side-on (,,,2:,2)-Cu2O2 complex as an active intermediate, and a single electron transfer (SET)-induced electrophilic aromatic substitution mechanism is proposed for the rate-determining CO bond forming process; this is consistent with experimental observations. Moreover, the inherent roles of, and requirement for, two copper ions in this reaction have been elucidated. [source] Asymmetric Sulfoxidation of Thioethers with Hydrogen Peroxide in Water Mediated by Platinum Chiral CatalystADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2005Alessandro Scarso Abstract Easy stereoselective oxidation of prochiral aryl alkyl sulfides 2 to the corresponding sulfoxides can be achieved in water-surfactant medium with inexpensive hydrogen peroxide mediated by the chiral platinum diphosphine complex {[(R)-BINAP]Pt(, - OH)}2(BF4)2 (1). Remarkable key features of general interest are (i) easy isolation of the products from catalyst by simple diethyl ether/water-surfactant two phase separation, (ii) catalyst loading as low as 1% mol, (iii) good yields, sulfoxide 3 to sulfone 4 ratio up to 200,:,1 and enantioselectivities up to 88%, (iv) mild experimental conditions. [source] Preferential Resistance of Dopaminergic Neurons to the Toxicity of Glutathione Depletion Is Independent of Cellular Glutathione Peroxidase and Is Mediated by TetrahydrobiopterinJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Ken Nakamura Abstract: Depletion of glutathione in the substantia nigra is one of the earliest changes observed in Parkinson's disease (PD) and could initiate dopaminergic neuronal degeneration. Nevertheless, experimental glutathione depletion does not result in preferential toxicity to dopaminergic neurons either in vivo or in vitro. Moreover, dopaminergic neurons in culture are preferentially resistant to the toxicity of glutathione depletion, possibly owing to differences in cellular glutathione peroxidase (GPx1) function. However, mesencephalic cultures from GPx1-knockout and wild-type mice were equally susceptible to the toxicity of glutathione depletion, indicating that glutathione also has GPx1-independent functions in neuronal survival. In addition, dopaminergic neurons were more resistant to the toxicity of both glutathione depletion and treatment with peroxides than nondopaminergic neurons regardless of their GPx1 status. To explain this enhanced antioxidant capacity, we hypothesized that tetrahydrobiopterin (BH4) may function as an antioxidant in dopaminergic neurons. In agreement, inhibition of BH4 synthesis increased the susceptibility of dopaminergic neurons to the toxicity of glutathione depletion, whereas increasing BH4 levels completely protected nondopaminergic neurons against it. Our results suggest that BH4 functions as a complementary antioxidant to the glutathione/glutathione peroxidase system and that changes in BH4 levels may contribute to the pathogenesis of PD. [source] Supramolecular Assembly of Gold Nanoparticles Mediated by Polypseudorotaxane with Thiolated , -Cyclodextrin,MACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2005Yu Liu Abstract Summary: A water-soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono-6-thio- , -cyclodextrin with poly(propylene glycol) bis(2-aminopropyl ether) (,,,2,000) in the presence of sodium borohydride in N,N -dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA-cleavage reagent. A typical TEM image of gold nanoparticle aggregate 2. [source] Self-sensitized Photodegradation of Membrane-bound Protoporphyrin Mediated by Chain Lipid Peroxidation: Inhibition by Nitric Oxide with Sustained Singlet Oxygen DamagePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2005Magdalena Niziolek ABSTRACT In the presence of exciting light, iron and reductants, the singlet oxygen (1O2)-generating sensitizer protoporphyrin IX (PpIX) induces free radical lipid peroxidation in membranes, but gradually degrades in the process. We postulated that NO, acting as a chain-breaking antioxidant, would protect PpIX against degradation and consequently prolong its ability to produce 1O2. This idea was tested by irradiating PpIX-containing liposomes (LUVs) in the presence of iron and ascorbate, and monitoring the cholesterol hydroperoxides 5,-OOH and 7,/,-OOH as respective 1O2 and free radical reporters. 5,-OOH accumulation, initially linear with light fluence, slowed progressively after prolonged irradiation, whereas 7,/,-OOH accumulation only accelerated after an initial lag. The active, but not spent, NO donor spermine NONOate (0.4 mM) virtually abolished 7,/,-OOH buildup as well as 5,-OOH slowdown. Increasing membrane phospholipid unsaturation hastened the onset of rapid chain peroxidation and 5,-OOH slowdown. Accompanying the 5,-OOH effect was a steady decrease in 1O2 quantum yield and PpIX fluorescence at 632 nm, both of which were inhibited by NO. An NO-inhibitable decay of PpIX fluorescence was also observed during dark incubation of 5,-OOH-bearing LUVs with iron and ascorbate, confirming a link between chain peroxidation and PpIX loss. By protecting PpIX in irradiated membranes, NO might select for and prolong purely 1O2 -mediated damage. Supporting this was our observation that 1O2 -mediated photoinactivation of a nonmembrane target, lactate dehydrogenase, slowed concurrently with 5,-OOH accumulation and that spermine NONOate prevented this. Thus, NO not only protected membrane lipids against PpIX-sensitized free radical damage, but PpIX itself, thereby extending its 1O2 -generating lifetime. Consistent findings were obtained using porphyrin-sensitized COH-BR1 cells. These previously unrecognized effects of NO could have important bearing on 5-aminolevulinate-based photodynamic therapy in which PpIX is metabolically deposited in tumor cells. [source] ORIGINAL RESEARCH,EPIDEMIOLOGY: Effect of Sexual Function on Health-Related Quality of Life Mediated by Depressive Symptoms in Cardiac Rehabilitation.THE JOURNAL OF SEXUAL MEDICINE, Issue 6 2010Findings of the SPARK Project in 493 Patients ABSTRACT Introduction., Empirical evidence suggests associations between cardiovascular diseases, sexual functioning, depressive symptoms, and quality of life. However, to date, the interrelation of these constructs has not been examined simultaneously in a structural analysis. Aim., To estimate the prevalence of sexual disorders and depressive symptoms and to examine the association between sexual disorders, depressive symptoms, and quality of life in patients in the rehabilitation of cardiovascular disorders. Aim., A postal survey in five German inpatient rehabilitation centers for cardiovascular diseases was conducted. Prevalence of sexual disorders and depressive symptoms were assessed using psychometrically sound instruments. To analyze complex associations, structural equation modeling was used. Main Outcome Measures., For epidemiological questions, proportions with 95% confidence intervals were calculated. The strength of association in structural equation models was expressed as a standardized regression coefficient. Results., Data from 493 patients were analyzed (response rate 22.7%). At least moderate erectile dysfunction proved to be present in 20.3% of men. The prevalence of female sexual dysfunction lay at 43.1%. At least moderate depressive symptoms were present in 14.4% of men and 16.5% of women. A considerable association between sexual functioning and quality of life was found in both sexes, which was largely mediated by depressive symptoms. Major drawbacks of the study are imprecision of the estimates due to limited sample size and questionable generalizability of the findings due to possible self-selection bias. Conclusions., Considering the high prevalence of depressive symptoms and their role as a mediating factor between sexual functioning and quality of life, it is recommended to routinely screen for depression in men and women with cardiac disease. Kriston L, Günzler C, Agyemang A, Bengel J, and Berner MM. Effect of sexual function on health-related quality of life mediated by depressive symptoms in cardiac rehabilitation. Findings of the SPARK project in 493 patients. J Sex Med 2010;7:2044,2055. [source] Highly Selective Acylation of Dimethylamine Mediated by Oxygen Atoms on Metallic Gold Surfaces,ANGEWANDTE CHEMIE, Issue 2 2010Bingjun Xu Komplett gekuppelt: Die Acylierung von Dimethylamin durch Kupplung mit Formaldehyd gelingt mit fast kompletter Selektivität bei niedriger Aktivierungsenergie und niedrigen Bedeckungen mit adsorbierten O-Atomen auf metallischem Gold. Der Sauerstoff erzeugt die aktivierte Zwischenstufe (CH3)2N(a), die das Carbonyl-Kohlenstoffatom des Aldehyds angreift (siehe Bild). Ein allgemeiner Mechanismus für die effiziente und selektive Acylierung von Aminen durch Au wird vorgeschlagen. [source] ChemInform Abstract: A Mild and Convenient One-Pot Two-Step Synthesis of Hydroxyiminodihydrobenzofurans Mediated by Silica Gel under Microwave Activation Conditions.CHEMINFORM, Issue 39 2010Deepak Kumar Barange Abstract Cyclic 1,3-dicarbonyl compounds (I) react with various nitroolefins to furnish the title products exclusively or predominantly as (E)-isomers. [source] ChemInform Abstract: Diastereo- and Enantioselective Direct Henry Reaction of Pyruvates Mediated by Chiral P-Spiro Tetraaminophosphonium Salts.CHEMINFORM, Issue 15 2010Daisuke Uraguchi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: One-Pot Multicomponent Synthesis of Azaindoles and Pyrroles from One Molecule of a Silicon-Tethered Diyne and Three or Two Molecules of Organonitriles Mediated by Zirconocene.CHEMINFORM, Issue 11 2010Shaoguang Zhang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Indolylindolines Mediated by t-BuNH2.CHEMINFORM, Issue 44 2009Oscar R. Suarez-Castillo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Palladium-Catalyzed Heteroaromatic Couplings Mediated by Microwave Irradiation.CHEMINFORM, Issue 17 2008Mauro Panunzio Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Highly Regioselective Propanoylation of Dihydroxybenzenes Mediated by Candida antarctica Lipase B in Organic Solvents.CHEMINFORM, Issue 16 2008Toshifumi Miyazawa Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Highly Diastereoselective Cyclocarbonylation of Allene-Aldehyde Mediated by Mo(CO)6: Synthesis of Bicyclic Lactones.CHEMINFORM, Issue 14 2008Kyoung-Jun Ko Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A New Manifold for the Morita Reaction: Diene Synthesis from Simple Aldehydes and Acrylates/Acrylonitrile Mediated by Phosphines.CHEMINFORM, Issue 10 2008Anders Palmelund Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Cycloisomerization of 1,6-Dienes Mediated by Lewis Super Acids Without Additives: Easy Access to Polysubstituted Six-Membered Carbocycles.CHEMINFORM, Issue 8 2007Fanny Grau Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Benign and Efficient Synthesis of 2-Substituted 4(3H)-Quinazolinones Mediated by Iron(III) Chloride Hexahydrate in Refluxing Water.CHEMINFORM, Issue 2 2007Guan-Wu Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Yb(OTf)3 -Catalyzed Oxidation of Alcohols with Iodosylbenzene Mediated by TEMPO.CHEMINFORM, Issue 50 2006Jean-Michel Vatele Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Applications of Asymmetric Hydrosilylations Mediated by Catalytic (DTBM-SEGPHOS)CuH.CHEMINFORM, Issue 46 2006Bruce H. Lipshutz Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] A Convenient Preparation of Aliphatic and Aromatic N-Sulfonylimines Mediated by Sulfamic Acid in Aqueous Media.CHEMINFORM, Issue 39 2006Zhenjiang Li Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Oxidative Deoximation by Supported Bismuth(III) Nitrate Mediated by DABCO under Microwave Irradiation.CHEMINFORM, Issue 3 2006Taraneh T. Niaki Abstract For Abstract see ChemInform Abstract in Full Text. [source] Optimization of Chemo-Enzymatic Epoxidation of Cyclohexene Mediated by Lipases.CHEMINFORM, Issue 50 2005Marcelo Alves Moreira Abstract For Abstract see ChemInform Abstract in Full Text. [source] An Effective and Highly Stereoselective Julia Olefination of Cyclopropyl Carbinol Mediated by CeCl3×7H2O/NaI.CHEMINFORM, Issue 45 2005Wei-Dong Z. Li Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of Isoaminile Mediated by Enzymes.CHEMINFORM, Issue 42 2005Fabrizio Antonietti Abstract For Abstract see ChemInform Abstract in Full Text. [source] Reductive Cross-Aldol Reaction Using Bromoaldehyde and an Aldehyde Mediated by Germanium(II): One-Pot, Large-Scale Protocol.CHEMINFORM, Issue 38 2005Makoto Yasuda Abstract For Abstract see ChemInform Abstract in Full Text. [source] | |||||||||||||||||||||||||||||||