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Various Chemical (various + chemical)
Selected AbstractsNonanoic acid , an experimental irritantCONTACT DERMATITIS, Issue 3 2003Jan E. Wahlberg Irritant contact dermatitis is defined as a non-immunological skin reaction following exposure to various chemical, mechanical and physical factors. It is known that the skin response to irritants depends on the irritant applied and differs between chemically different irritants. Sodium lauryl sulfate (SLS) is an anionic detergent and the most frequently used substance in experimental irritant contact dermatitis. In 1980, it was suggested that nonanoic acid (NNA) could be used as a positive control when patch testing. Since then, NNA has been used as an experimental irritant in several studies and has been used as a chemically different substance compared to SLS. The present article presents a review of the application of NNA in studies on skin irritancy and experimental irritant contact dermatitis. [source] Captopril and its synthesis from chiral intermediatesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2001R Chirumamilla Abstract Captopril is an antihypertensive agent that inhibits the angiotensin-converting enzyme of the renin,angiotensin system. Chiral intermediates are used in the synthesis of the drug. These intermediates are obtained by resolution of racemic compounds or by chemical, biocatalytic methods and or by asymmetric synthesis by biocatalytic process. This article reviews the various chemical and biochemical processes involved in the synthesis of the chiral drug, including the pharmacological action of captopril. © 2001 Society of Chemical Industry [source] Microstructure,property,quality-correlated paint design: An LMC-based approachAICHE JOURNAL, Issue 1 2009Jie Xiao Abstract Paint is designed to offer various chemical and physical properties for surface protection, styling, and appearance. Nevertheless, the anticipated quality of the surface coating is frequently unsatisfactory, which is often attributed to paint formulation. As new demands on coating performance continuously emerge, paint formulation design becomes much more challenging than ever. It is recognized that paint design can be significantly improved with the help of advanced computational methods, as they can provide great freedom and control over the investigation of paint formulation through any number of in silico experiments virtually under any application conditions. This article introduces a lattice Monte Carlo based computational methodology for paint formulation design. By this methodology and structural analysis techniques, a variety of correlations among paint material, curing condition, coating microstructure, and coating qualities can be generated, which are critical for the development of superior paint formulations. A comprehensive study on acrylic-melamine-based paint design and analysis demonstrates the methodological efficacy. © 2008 American Institute of Chemical Engineers AIChE J, 2009 [source] Comparison of Structural and Chemical Properties of Black and Red Human Hair Melanosomes,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2005Yan Liu ABSTRACT Melanosomes in black and red human hair are isolated and characterized by various chemical and physical techniques. Different yields of 4-amino-hydroxyphenolanaline by HI hydrolysis (a marker for pheomelanin) and pyrrole-2,3,5-tricarboxylic acid by KMnO4/H+ oxidation (a marker for eumelanin) indicate that the melanosomes in black hair are eumelanosomes, whereas those in red hair are mainly pheomelanosomes. Atomic force microscopy reveals that eumelanosomes and pheomelanosomes have ellipsoidal and spherical shapes, respectively. Eumelanosomes maintain structural integrity upon extraction from the keratin matrix, whereas pheomelanosomes tend to fall apart. The black-hair eumelanosomes have an average of 14.6 ± 0.5% amino acids content, which is attributed to the internal proteins entrapped in the melanosomes granules. The red-hair melanosomes contain more than 44% of amino acid content even after extensive proteolytic digestion. This high content of amino acids and the poorly reserved integrity of red-hair melanosomes suggest that some proteins are possibly covalently bonded with the melanin constituents in addition to those that are entrapped inside the melanin species. Soluene solubilization assay indicates the absorbance of melanin per gram of sample, adjusted for the amino acid content, is a factor of 2.9 greater for the black-hair melanosomes than the red-hair melanosomes. Metal analysis reveals significant amounts of diverse heavy metal ions bound to the two types of melanosomes. The amount of Cu(II) and Zn(II) are similar but Fe(III) content is four times higher in the red-hair melanosomes. 13C solid-state nuclear magnetic resonance spectra and infrared spectra are presented and are shown to be powerful techniques for discerning differences in the amino acid contents, the 5,6-dihydroxyindole-2-carboxylic acid:5,6-dihydroxyindole ratio, and the degree of cross-linking in the pigment. Excellent agreement is observed between these spectral results and the chemical degradation data. [source] Control of black foot disease in grapevine nurseriesPLANT PATHOLOGY, Issue 4 2007F. Halleen Black foot disease of grapevines is a decline and dieback disease caused by a soilborne pathogen complex including Cylindrocarpon liriodendri, C. macrodidymum, Campylocarpon fasciculare and Campyl. pseudofasciculare. These pathogens cause primary infections of roots and basal ends of grafted cuttings in nursery soils. Thirteen fungicides were screened in vitro for mycelial inhibition of these pathogens. Prochloraz manganese chloride, benomyl, flusilazole and imazalil were the most effective fungicides tested, and were subsequently included in semi-commercial field trials. Basal ends of grafted cuttings were dipped in various chemical and biological treatments prior to planting in open-rooted nurseries. Black foot pathogens were not isolated from grafted cuttings prior to planting. Additional treatments involved soil amendments with Trichoderma formulations and hot water treatment of dormant nursery grapevines. Field trials were evaluated after eight months. Isolations from uprooted plants revealed low levels of black foot pathogens in the roots of untreated control plants, and significantly higher levels in basal ends of rootstocks. The incidence of black foot pathogens, as well as that of Petri disease pathogens, was not significantly and/or consistently reduced by the majority of chemical or biological treatments. However, these pathogens were not isolated from uprooted plants that were subjected to hot water treatment. It is therefore recommended that hot water treatment of dormant nursery plants be included in an integrated strategy for the proactive management of these diseases in grapevine nurseries. [source] N -Malonyl-1,2-dihydroisoquinoline as a Novel Carrier for Specific Delivery of Drugs to the BrainARCHIV DER PHARMAZIE, Issue 1 2010Mohamed Abdel-Aziz Abstract N -Malonyl-1,2-dihydroisoquinoline derivatives were synthesized and investigated as a novel carrier system for site-specific and sustained delivery of drugs to the brain. Such carriers are expected to be stable against air oxidation due to the presence of the carbonyl group close to nitrogen of the dihydroisoquinoline. Reduction of the prepared isoquinolinium quaternary derivatives with sodium dithionite afforded a novel group of N -malonyl-1,2-dihydroisoquinoline chemical delivery systems (CDS). The synthesized N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were subjected to various chemical and biological investigations to evaluate their ability to cross the blood-brain barrier (BBB), and to be oxidized biologically into their corresponding quaternary derivatives. The in-vitro oxidation studies showed that the designed N -malonyl-1,2-dihydroisoquinoline chemical delivery system could be oxidized into its corresponding quaternary derivatives at an adequate rate. The in-vivo distribution studies showed that these N -malonyl-1,2-dihydroisoquinoline chemical delivery systems were able to cross the blood-brain barrier at detectable concentrations. [source] Enantioresolution of dl -penicillamineBIOMEDICAL CHROMATOGRAPHY, Issue 1 2010Ravi Bhushan Abstract Penicillamine (PenA) is a nonproteinogenic amino acid containing a thiol group. The three functional groups in penicillamine undergo characteristic chemical reactions and differ in their ability to participate in various chemical and biochemical reactions. d -penicillamine is more active pharmacologically, while the l -isomer occurs ,naturally'. This review deals with the enantioresolution of PenA both by direct and indirect methods using liquid chromatography. HPLC separation of its diastereomers prepared with different chiral derivatizing reagents (on reversed-phase columns) and separation of the derivatives prepared with achiral reagents (on chiral columns or via ligand exchange mode) has been discussed. Separation of enantiomers tagged with achiral reagent (to add a chromophore for ehanced detection) when there is no diastereomer formation has been considered separately. In addition, application of PenA and its derivatives as chiral selector for enentioresolution of certain other compounds has also been discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ligand binding strategies of human serum albumin: How can the cargo be utilized?CHIRALITY, Issue 1 2010Ankita Varshney Abstract Human serum albumin (HSA), being the most abundant carrier protein in blood and a modern day clinical tool for drug delivery, attracts high attention among biologists. Hence, its unfolding/refolding strategies and exogenous/endogenous ligand binding preference are of immense use in therapeutics and clinical biochemistry. Among its fellow proteins albumin is known to carry almost every small molecule. Thus, it is a potential contender for being a molecular cargo/or nanovehicle for clinical, biophysical and industrial purposes. Nonetheless, its structure and function are largely regulated by various chemical and physical factors to accommodate HSA to its functional purpose. This multifunctional protein also possesses enzymatic properties which may be used to convert prodrugs to active therapeutics. This review aims to highlight current overview on the binding strategies of protein to various ligands that may be expected to lead to significant clinical applications. Chirality, 2010. © 2009 Wiley-Liss, Inc. [source] Purification and Characterization of Acid Phosphatase from the Egg of the Lady Beetle, Harmonia axyridis (Coccinellidae: Coleoptera)ENTOMOLOGICAL RESEARCH, Issue 1 2004Jun Hyuk LEE ABSTRACT Acid phosphatase (AP) in the egg of the lady beetle, Harmonia axyridis, was purified and characterized. Ammonium sulfate precipitation, CM column and isoelectrofocusing (IEF) were applied to purify an estimated molecular weight of 66 kDa AP. The purity was checked by SDS PAGE, native PAGE and Western blot. AP was detected in the hemolymph of the female and the egg, but not in the male on the blotting. Km of AP for a substrate, p -nitrophenyl phosphate (p -NPP), was 1.64 x 10 -4 M. AP had the optimum enzymatic activity at pH 3.5. In inhibition tests performed with various chemicals, ammonium molybdate suppressed 99% of the enzyme activity of AP even at the concentration of 5 x 10 -4 mM. AP was stable up to 50°C. [source] Secretion of cortisol and aldosterone as a vulnerable target for adrenal endocrine disruption , screening of 30 selected chemicals in the human H295R cell modelJOURNAL OF APPLIED TOXICOLOGY, Issue 8 2008Erik Ullerås Abstract The adrenal gland is a vulnerable target for toxic insult. Disruption of adrenal steroidogenesis and hormone secretion may cause serious effects on human health. A human in vitro model is needed to predict effects, and elucidate mechanisms of endocrine disruption and adrenal toxicity. The human adrenocortical cell line H295R has been used to screen for effects on sex hormones. Here, we have analyzed the effect of 30 potential endocrine disrupting chemicals on the secretion of cortisol and aldosterone from the H295R cells, using specific ELISA assays. The effect of chemicals was analyzed for basal and forskolin- or angiotensin II-stimulated hormone secretion. The chemicals were tested at the highest concentration where they displayed no evident unspecific cytotoxicity. Quantitative and qualitative differences in effects on hormone secretion were demonstrated for the various chemicals. A subset of the chemicals displayed different effects on cortisol and aldosterone secretion, and in some cases the effects were different between basal and stimulated hormone secretion. Aminoglutethimide, prochloraz, ketoconazole, 6-hydroxyflavone, imazalil and etomidate had the most marked inhibitory effects on cortisol (with or without forskolin) and ketoconazole, 6-hydroxyflavone, imazalil and etomidate had the most marked effects on aldosterone (with or without angiotensin II). The results are discussed in terms of known effects, structural similarity and possible mechanisms. We have shown that adrenal steroidogenesis is a vulnerable target for toxic insult and that the H295R assay is a useful in vitro model for screening purposes. Copyright © 2008 John Wiley & Sons, Ltd. [source] Power generation from coal and biomass based on integrated gasification combined cycle concept with pre- and post-combustion carbon capture methodsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2009Calin-Cristian Cormos Abstract Gasification technology is a process in which solid fuel is partially oxidised by oxygen and steam/water to produce a combustible gas called syngas (mainly a mixture of hydrogen and carbon monoxide). Syngas can be used either for power generation or processed to obtain various chemicals (hydrogen, ammonia, methanol, etc.). This article evaluates the possibilities of solid fuel decarbonisation by capturing carbon dioxide resulted form thermo-chemical conversion of solid fuel using gasification. Evaluation is focused on power generation technology using syngas produced by solid fuel gasification (so-called integrated gasification combined cycle,IGCC). Case studies analysed in the article are using a mixture of coal and biomass (sawdust) to produce around 400 MW electricity simultaneously with capturing about 90% of the feedstock carbon. Various carbon dioxide capture options (post- and pre-combustion) are compared with situation of no carbon capture in terms of plant configurations, energy penalty, CO2 emissions, etc. Plant options are modelled using ChemCAD, and simulation results are used to assess the plant performances. Plant flexibility and future improvements are also discussed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Significance of error-avoiding mechanisms for oxidative DNA damage in carcinogenesisCANCER SCIENCE, Issue 4 2007Teruhisa Tsuzuki Reactive oxygen species (ROS) are produced through normal cellular metabolism, and their formation is further enhanced by exposure to ionizing radiation and various chemicals. ROS attack DNA, and the resulting oxidative DNA damage is considered to contribute to aging, carcinogenesis and neurodegeneration. Among various types of oxidative DNA damage, 8-oxo-7,8-dihydroguanine (8-oxoguanine or 8-oxoG) is the most abundant, and plays significant roles in mutagenesis because of its ability to pair with adenine as well as cytosine. Enzymatic activities that may be responsible for preventing 8-oxoG-evoked mutations were identified in mammalian cells. We have focused on the following three enzymes: MTH1, OGG1 and MUTYH. MTH1 is a mammalian ortholog of Escherichia coli MutT, which hydrolyzes 8-oxo-dGTP to its monophosphate form in nucleotide pools, thereby preventing incorporation of the mutagenic substrate into DNA. OGG1, a functional counterpart of E. coli MutM, has an 8-oxoG DNA glycosylase activity. MUTYH, a mammalian ortholog of E. coli MutY, excises an adenine paired with 8-oxoG. These three enzymes are thought to prevent mutagenesis caused by 8-oxoG in mammals. To analyze the functions of mammalian MTH1 (Mth1), OGG1 (Ogg1) and MUTYH (Mutyh) in vivo, we established mutant mice for these three enzymes by targeted mutagenesis, and investigated spontaneous tumorigenesis as well as mutagenesis. Here we discuss our recent investigation of mutagenesis and carcinogenesis in these mutant mice. (Cancer Sci 2007; 98: 465,470) [source] | ||||||||||||||||