|
| ||
|
|
||
Acid N (acid + n)
Selected AbstractsChemInform Abstract: Features of Reaction of 4-Chlorobenzenesulfonic Acid N-(1-Aryl-2,2,2-trichloroethyl)amide with Benzyl Mercaptan.CHEMINFORM, Issue 52 2008I. B. Rozentsveig 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] Synthesis and Some Chemical Transformations of (Z)- and (E)-2-Acetyl-1-ferrocenyl-3-methylbuta-1,3-dienes , A New Type of Cationic CycloadditionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2004Elena I. Klimova Abstract Dehydration of (E)- and (Z)-2-acetyl-1-ferrocenyl-3-methylbut-1-en-3-ols gave the corresponding (E)- and (Z)-2-acetyl-1-ferrocenyl-3-methylbuta-1,3-dienes, which have a cross-conjugated system of three double bonds. These heterotrienes readily afford the products of linear and cyclodimerization by following a cationic cyclodimerization mechanism; they also form Diels,Alder adducts with azodicarboxylic and maleic acid N -phenylimides. The spatial structures of (E)-2-acetyl-1-ferrocenyl-3-methylbuta-1,3-diene, (E,E)-1,5-diferrocenyl-2-isopropenyl-6-isopropylidene-3-methyl-1,3-octadiene-7-one, and 7-ferrocenyl-4-(ferrocenylmethylidene)-8-isopropylidene-1,3,5-trimethyl-9-oxabicyclo[3.3.1]non-2-ene were elucidated by X-ray diffraction analyses of single crystals. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Reactivity of the heme,dioxygen complex of the inducible nitric oxide synthase in the presence of alternative substratesFEBS JOURNAL, Issue 1 2006David Lefèvre-Groboillot Single turnover reactions of the inducible nitric oxide synthase oxygenase domain (iNOSoxy) in the presence of several non ,-amino acid N -hydroxyguanidines and guanidines were studied by stopped-flow visible spectroscopy, and compared with reactions using the native substrates l -arginine (l -arg) or N, -hydroxy- l -arginine (NOHA). In experiments containing dihydrobiopterin, a catalytically incompetent pterin, and each of the studied substrates, l -arg, butylguanidine (BuGua), para -fluorophenylguanidine (FPhGua), NOHA, N -butyl- and N -(para -fluorophenyl)- N,-hydroxyguanidines (BuNOHG and FPhNOHG), the formation of a iron(II) heme,dioxygen intermediate (FeIIO2) was always observed. The FeIIO2 species then decayed to iron(III) iNOSoxy at rates that were dependent on the nature of the substrate. Identical reactions containing the catalytically competent cofactor tetrahydrobiopterin (BH4), iNOSoxy and the three N -hydroxyguanidines, all exhibited an initial formation of an FeIIO2 species that was successively converted to an FeIIINO complex and eventually to high-spin iron(III) iNOSoxy. The formation and decay kinetics of the FeIIINO complex did not vary greatly as a function of the N -hydroxyguanidine structure, but the formation of FeIIINO was substoichiometric in the cases of BuNOHG and FPhNOHG. Reactions between BH4 -containing iNOSoxy and BuGua exhibited kinetics similar to those of the corresponding reaction with l -arginine, with formation of an FeIIO2 intermediate that was directly converted to high-spin iron(III) iNOSoxy. In contrast, no FeIIO2 intermediate was observed in the reaction of BH4 -containing iNOSoxy and FPhGua. Multi-turnover reaction of iNOS with FPhGua did not lead to formation of NO or to hydroxylation of the substrate, contrary to reactions with BuGua or l -arg. Our results reveal how different structural and chemical properties of NOS substrate analogues can impact on the kinetics and reactivity of the FeIIO2 intermediate, and support an important role for substrate pKa during NOS oxygen activation. [source] Nitrogen utilization by Hylocomium splendens in a boreal forest fertilization experimentFUNCTIONAL ECOLOGY, Issue 3 2006Å. FORSUM Summary 1Nitrogen uptake in the terricolous bryophyte Hylocomium splendens (Hedw.) B.S.G. was studied in a boreal forest long-term N-treatment experiment including control plots, N-addition plots (50 kg N ha,1 year,1 for 8 years) and recovery plots (50 kg N ha,1 year,1 for 5 years and thereafter no N addition for 3 years). 2A main objective was to explore whether the N treatments changed bryophyte uptake of different inorganic and organic N forms. In addition, we estimated the contribution of N from throughfall precipitation to the bryophyte N supply. 3The results demonstrated that bryophyte N uptake was similar in all the long-term N-treatment plots. Hylocomium splendens took up more 15N labelled than or glycine when these N forms were applied in situ by the spraying of solutions with N concentrations similar to those in precipitation. 4Analysis of the precipitation collected beneath the closed tree canopy from late May to early October revealed that it contributed 2·0 kg N ha,1 during the period studied, distributed between (78%), amino acid N (17%) and (5%). 5The study highlights that, in addition to analyses of and (normally included in standard environmental monitoring of precipitation), analysis of amino acid N must be performed to account fully for the precipitation N input to bryophytes in boreal forest ecosystems. [source] Effects of the Interaction Between , -Carboline-3-carboxylic acid N -Methylamide and Polynucleotides on Singlet Oxygen Quantum Yield and DNA Oxidative DamagePHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2007Iñigo X. García-Zubiri The complexation of , -carboline-3-carboxylic acid N -methylamide (,CMAM) with the sodium salts of the nucleotides polyadenylic (Poly A), polycytidylic (Poly C), polyguanylic (Poly G), polythymidylic (Poly T) and polyuridylic (Poly U) acids, and with double stranded (dsDNA) and single stranded deoxyribonucleic acids (ssDNA) was studied at pH 4, 6 and 9. Predominant 1:1 complex formation is indicated from Job plots. Association constants were determined using the Benesi,Hildebrand equation. ,CMAM-sensitized singlet oxygen quantum yields were determined at pH 4, 6 and 9, and the effects on this of adding oligonucleotides, dsDNA and ssDNA were studied at the three pH values. With dsDNA, the effect on ,CMAM triplet state formation was also determined through triplet,triplet transient absorption spectra. To evaluate possible oxidative damage of DNA following singlet oxygen ,CMAM photosensitization, we used thiobarbituric acid-reactivity assays and electrophoretic separation of DNA assays. The results showed no oxidative damage at the level of DNA degradation or strand break. [source] Measurement of xylem sap amino acid concentrations in conjunction with whole tree transpiration estimates spring N remobilization by cherry (Prunus avium L.) treesPLANT CELL & ENVIRONMENT, Issue 12 2002G. GRASSI Abstract Prunus avium trees were grown in sand culture for one vegetative season with contrasting N supplies, in order to precondition their N storage capacities. During the spring of the second year a constant amount of 15N was supplied to all the trees, and the recovery of unlabelled N in the new biomass production was used as a direct measure of N remobilization. Destructive harvests were taken during spring to determine the pattern of N remobilization and uptake. Measurements of both xylem sap amino acid profiles and whole tree transpiration rates were taken, to determine whether specific amino acids are translocated as a consequence of N remobilization and if remobilization can be quantified by calculating the flux of these amino acids in the xylem. Whereas remobilization started immediately after bud burst, N derived from uptake by root appeared in the leaves only 3 weeks later. The tree internal N status affected both the amount of N remobilization and its dynamics. The concentration of xylem sap amino acids peaked shortly after bud burst, concurrently with the period of fastest remobilization. Few amino acids and amides (Gln, Asn and Asp) were responsible for most of N translocated through the xylem; however, their relative concentration varied over spring, demonstrating that the transport of remobilized N occurred mainly with Gln whereas transport of N taken up from roots occurred mainly with Asn. Coupling measurements of amino acid N in the xylem sap with transpiration values was well correlated with the recovery of unlabelled N in the new biomass production. These results are discussed in relation to the possibility of measuring the spring remobilization of N in field-grown trees by calculating the flux of N translocation in the xylem. [source] A sensitive and selective determination method of histamine by HPLC with intramolecular excimer-forming derivatization and ,uorescence detectionBIOMEDICAL CHROMATOGRAPHY, Issue 8 2003Takashi Yoshitake Abstract A highly sensitive, selective and simple method is described for the determination of histamine by high-performance liquid chromatography (HPLC) with ,uorescence detection. The method is based on an intramolecular excimer-forming ,uorescence derivatization of histamine with 4-(1-pyrene)butyric acid N -hydroxysuccinimide ester (PSE), followed by reversed-phase HPLC. Histamine, having two amino moieties in a molecule, was converted to the dipyrene-labeled derivative by reaction with PSE. The derivative afforded intramolecular excimer ,uorescence (450,540 nm), which can clearly be discriminated from the monomer ,uorescence (370,420 nm) emitted from PSE. Typically, a 10 µL sample solution was mixed with 100 µL of derivatization reagent solution, which was a mixture of 0.5 mm PSE in acetonitrile and 0.5 mm potassium carbonate in water (8:2, v/v). The derivatization was carried out at 100°C for 90 min. The PSE derivative of histamine could be separated by reversed-phase ODS column with isocratic elution using acetonitrile:water (82:18, v/v) containing 0.03% triethylamine. The detection limit (singnal-to-noise ratio = 3) of histamine was 0.5 fmol for a 30 µL injection. The method was successfully applied to the determination of histamine in human urine, and had enough selectivity and sensitivity for urinary histamine quanti,cation. Copyright © 2003 John Wiley & Sons, Ltd. [source] Anti-Inflammatory and Anti-Tumor-Promoting Effects of Triterpene Acids and Sterols from the Fungus Ganoderma lucidumCHEMISTRY & BIODIVERSITY, Issue 2 2007Toshihiro Akihisa Abstract A series of lanostane-type triterpene acids, including eleven lucidenic acids (3, 4, 9, 10, 13,19) and six ganoderic acids (20,22, 24, 26, 27), as well as six sterols (28,33), all isolated from the fruiting bodies of the fungus Ganoderma lucidum, were examined for their inhibitory effects on the induction of Epstein,Barr virus early antigen (EBV-EA) by 12- O -tetradecanoylphorbol-13-acetate (TPA) in Raji cells, a known primary screening test for anti-tumor promoters. All of the compounds tested, except for ganolactone (27) and three sterols (29,31), showed potent inhibitory effects on EBV-EA induction, with IC50 values of 235,370,mol ratio/32,pmol TPA. In addition, nine lucidenic acids (1, 2, 5,8, 11, 12, 18) and four ganoderic acids (20, 23,25) were found to inhibit TPA-induced inflammation (1,,g/ear) in mice, with ID50 values of 0.07,0.39,mg per ear. Further, 20-hydroxylucidenic acid N (18) exhibited inhibitory effects on skin-tumor promotion in an in vivo two-stage mouse-skin carcinogenesis test based on 7,12-dimethylbenz[a]anthracene (DMBA) as initiator, and with TPA as promoter. [source] Treatment of symptomatic diabetic polyneuropathy with the antioxidant ,-lipoic acid: a meta-analysisDIABETIC MEDICINE, Issue 2 2004D. Ziegler Abstract Aims To determine the efficacy and safety of 600 mg of ,-lipoic acid given intravenously over 3 weeks in diabetic patients with symptomatic polyneuropathy. Methods We searched the database of VIATRIS GmbH, Frankfurt, Germany, for clinical trials of ,-lipoic acid according to the following prerequisites: randomized, double-masked, placebo-controlled, parallel-group trial using ,-lipoic acid infusions of 600 mg i.v. per day for 3 weeks, except for weekends, in diabetic patients with positive sensory symptoms of polyneuropathy which were scored by the Total Symptom Score (TSS) in the feet on a daily basis. Four trials (ALADIN I, ALADIN III, SYDNEY, NATHAN II) comprised n = 1258 patients (,-lipoic acid n = 716; placebo n = 542) met these eligibility criteria and were included in a meta-analysis based on the intention-to-treat principle. Primary analysis involved a comparison of the differences in TSS from baseline to the end of i.v. Treatment between the groups treated with ,-lipoic acid or placebo. Secondary analyses included daily changes in TSS, responder rates (, 50% improvement in TSS), individual TSS components, Neuropathy Impairment Score (NIS), NIS of the lower limbs (NIS-LL), individual NIS-LL components, and the rates of adverse events. Results After 3 weeks the relative difference in favour of ,-lipoic acid vs. placebo was 24.1% (13.5, 33.4) (geometric mean with 95% confidence interval) for TSS and 16.0% (5.7, 25.2) for NIS-LL. The responder rates were 52.7% in patients treated with ,-lipoic acid and 36.9% in those on placebo (P < 0.05). On a daily basis there was a continuous increase in the magnitude of TSS improvement in favour of ,-lipoic acid vs. placebo which was noted first after 8 days of treatment. Among the individual components of the TSS, pain, burning, and numbness decreased in favour of ,-lipoic acid compared with placebo, while among the NIS-LL components pin-prick and touch-pressure sensation as well as ankle reflexes were improved in favour of ,-lipoic acid after 3 weeks. The rates of adverse events did not differ between the groups. Conclusions The results of this meta-analysis provide evidence that treatment with ,-lipoic acid (600 mg/day i.v.) over 3 weeks is safe and significantly improves both positive neuropathic symptoms and neuropathic deficits to a clinically meaningful degree in diabetic patients with symptomatic polyneuropathy. Diabet. Med. 21, 114,121 (2004) [source] Lipid biomarkers, pigments and cyanobacterial diversity of microbial mats across intertidal flats of the arid coast of the Arabian Gulf (Abu Dhabi, UAE)FEMS MICROBIOLOGY ECOLOGY, Issue 3 2008Raeid M.M. Abed Abstract Variations in morphology, fatty acids, pigments and cyanobacterial community composition were studied in microbial mats across intertidal flats of the arid Arabian Gulf coast. These mats experience combined extreme conditions of salinity, temperature, UV radiation and desiccation depending on their tidal position. Different mat forms were observed depending on the topology of the coast and location. The mats contained 63 fatty acids in different proportions. The increased amounts of unsaturated fatty acids (12,39%) and the trans/cis ratio (0.6,1.6%) of the cyanobacterial fatty acid n- 18:1,9 in the higher tidal mats suggested an adaptation of the mat microorganisms to environmental stress. Chlorophyll a concentrations suggested lower cyanobacterial abundance in the higher than in the lower intertidal mats. Scytonemin concentrations were dependent on the increase in solar irradiation, salinity and desiccation. The mats showed richness in cyanobacterial species, with Microcoleus chthonoplastes and Lyngbya aestuarii morphotypes as the dominant cyanobacteria. Denaturing gradient gel electrophoresis patterns suggested shifts in the cyanobacterial community dependent on drainage efficiency and salinity from lower to higher tidal zones. We conclude that the topology of the coast and the variable extreme environmental conditions across the tidal flat determine the distribution of microbial mats as well as the presence or absence of different microorganisms. [source] Protein profiling of organic stone matrix and urine from dogs with urolithiasisJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5-6 2006S. Forterre Summary Two-thirds of the organic matrix in urinary stones consists of proteins. Their relationship to calculogenesis remains controversial with regard to their effect as inhibitors or promoters during stone formation. The purpose of the present study was to determine the differences in peptide and protein pattern between the urine of stone formers (n = 23) and control dogs (n = 12), as well as between organic matrix of different urinary stones (struvite n = 11, calcium oxalate n = 8, uric acid n = 4) using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry. Specific differences in protein and peptide profiles were found in the organic matrix of different mineral compositions. Characteristic differences were also found in urinary peptide and protein pattern especially in molecular masses below 20 kDa between affected and healthy dogs. Based on the obtained molecular masses they were in some cases tentatively identified as proteins that are known to be involved in stone formation in humans. The study shows that in dogs, specific-urinary peptides and proteins might be associated with urolithiasis. It indicates the importance to further characterize those proteins for possible diagnostic purposes in prognosis and therapy. [source] Structural analysis of thin films of novel polynorbornene derivatives by grazing incidence X-ray scattering and specular X-ray reflectivity along with ellipsometryJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Taek Joon Lee In the present study, structural analyses using synchrotron grazing incidence X-ray scattering, specular reflectivity and ellipsometry were performed on thin films of two novel polynorbornene derivatives, chiral poly(norbornene acid methyl ester) and racemic poly(norbornene acid n -butyl ester), which are potential low dielectric constant materials for advanced microelectronic and display applications. These analyses provided important information on the structure, electron density gradient across the film thickness, chain orientation, refractive index and thermal expansion characteristics of the polymers in substrate-supported thin films. The structural characteristics and properties of the thin films depended on the tacticity of the polymer chain and were further influenced by the film thickness and thermal annealing history. [source] Determination of paclitaxel in human and rat blood samples after administration of low dose paclitaxel by HPLC-UV detectionBIOMEDICAL CHROMATOGRAPHY, Issue 3 2007Haruo Yonemoto Abstract A simple and sensitive HPLC-UV method was developed for the determination of paclitaxel (TXL) in human and rat blood samples. 4-Hydroxybenzoic acid n -hexyl ester was used as an internal standard. TXL was extracted by a liquid,liquid extraction with tert -butylmethyl ether. The disturbing peaks in the case of serum sample were removed by pre-extraction with hexane. The separation of TXL was achieved within 25 min using an ODS column with 50% acetonitrile aqueous solution as a mobile phase at a flow rate of 1.0 mL/min. The eluent was monitored at 230 nm, and the resulted retention times of TXL and IS were 11.2 and 20.4 min. The detection limits of TXL for human plasma, serum and rat plasma samples at a signal-to-noise ratio of 3 were 10, 9.5 and 7.5 ng/mL, respectively. The proposed methods were applicable to the determination of TXL in human patients' plasma ranging from 15 to 27 ng/mL. Furthermore, monitoring of the time course of TXL after its single administration to rat could be demonstrated. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||