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Hydrophilic Compounds (hydrophilic + compound)
Selected AbstractsLow cross-reactivity of T-cell responses against lipids from Mycobacterium bovis and M. avium paratuberculosis during natural infectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 11 2009Ildiko Van Rhijn Abstract Although CD1 proteins are known to present mycobacterial lipid antigens to T cells, there is little understanding of the in vivo behavior of T cells restricted by CD1a, CD1b and CD1c, and the relative immunogenicity and immunodominance of individual lipids within the total array of lipids that comprise a bacterium. Because bovines express multiple CD1 proteins and are natural hosts of Mycobacterium bovis and Mycobacterium avium paratuberculosis (MAP), we used them as a new animal model of CD1 function. Here, we report the surprisingly divergent responses against lipids produced by these two pathogens during infection. Despite considerable overlap in lipid content, only three out of 69 animals cross-react with M. bovis and MAP total lipid preparations. The unidentified immunodominant compound of M. bovis is a hydrophilic compound, whereas the immunodominant lipid of MAP is presented by CD1b and was identified as glucose monomycolate (GMM). The preferential recognition of GMM antigen by MAP-infected cattle may be explained by the higher expression of GMM by MAP than by M. bovis. The bacterial species-specific nature of the CD1-restricted, adaptive T-cell response affects the approach to development of lipid based immunodiagnostic tests. [source] Recent developments in peptide stereoisomer separations by capillary electromigration techniquesELECTROPHORESIS, Issue S1 2009Gerhard K. E. Scriba Abstract The stereochemistry of peptides determines their physicochemical and biological activities. Thus, analytical methods that are able to discriminate between peptide stereoisomers are important. As peptides are typically hydrophilic compounds, many methods for the separation of peptide diastereomers and enantiomers have been developed by capillary electromigration techniques. Moreover, peptide enantiomers displayed unique migration behavior such as a pH-dependent change of the enantiomer migration order in CD-mediated enantioseparations in CE making them ideal compounds to study mechanistic effects of enantioseparations. The present short review summarizes recent developments in the separation of stereoisomers of peptide and peptidomimetics by capillary electromigration techniques. Moreover, recent NMR and molecular modeling studies as well as investigation on the effect of buffer additives on complex formation will be discussed as attempts to understand mechanistic aspects of peptide enantioseparations and to analyze the structure of peptide-CD complexes. [source] Emerging pollutants in the North Sea in comparison to Lake Ontario, Canada, dataENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Jens Arne Andresen Abstract In the present study, the concentrations and fate of contaminants such as organophosphate flame retardants and plasticizers, musk compounds such as galaxolide (HHCB), tonalide (AHTN), musk ketone and musk xylene, the bactericide triclosan, as well as the metabolites HHCB-lactone and triclosan-methyl were compared in the aqueous phase of the German Bight (North Sea). The concentrations of these compounds were around 1 to 10 ng/L in nearshore areas, and the concentrations were lower in the more pristine areas. The highest concentrations were determined for tris-(2-chloro- isopropyl) phosphate in the North Sea with concentration exceeding 10 ng/L even for the offshore samples. The samples contained 1 to 20 ng/L chlorinated organophosphates, approximately 1 ng/L nonchlorinated organophosphates, and 0.3 to 3 ng/L fragrance compounds. Some samples from Lake Ontario (Canada) were analyzed in comparison. Per capita emissions were calculated for both regions. These emissions were compared and turned out to be very similar for the Canadian and German locations. For the North Sea, some observations concerning stability, dilution, and degradation, as well as sources of the respective substances, were performed. These data indicate that the chlorinated organophosphates and some musk fragrances exhibit half lives exceeding the residence times and thus can be considered to be persistent in this ecosystem. In the German Bight, the river Elbe is the dominating source for the more hydrophilic compounds, such as chlorinated organophosphate flame retardants, which are diluted only into the North Sea. However, for the more lipophilic compounds such as the musk fragrances, different input patterns as well as distribution patterns are relevant, though the river Elbe is still a major source of pollution to the German Bight of the North Sea. The data seem to indicate either relevant inputs further west of the sampling area or mobilization from the sediments. [source] Blood,brain barrier damage and brain penetration of antiepileptic drugs: Role of serum proteins and brain edemaEPILEPSIA, Issue 4 2009Nicola Marchi Summary Purpose:, Increased blood,brain barrier (BBB) permeability is radiologically detectable in regions affected by drug-resistant epileptogenic lesions. Brain penetration of antiepileptic drugs (AEDs) may be affected by BBB damage. We studied the effects of BBB damage on brain distribution of hydrophilic [deoxy-glucose (DOG) and sucrose] and lipophilic (phenytoin and diazepam) molecules. We tested the hypothesis that lipophilic and hydrophilic drug distribution is differentially affected by BBB damage. Methods:, In vivo BBB disruption (BBBD) was performed in rats by intracarotid injection of hyperosmotic mannitol. Drugs (H3-sucrose, 3H-deoxy-glucose, 14C-phenytoin, and C14-diazepam) or unlabeled phenytoin was measured and correlated to brain water content and protein extravasation. In vitro hippocampal slices were exposed to different osmolarities; drug penetration and water content were assessed by analytic and densitometric methods, respectively. Results:, BBBD resulted in extravasation of serum protein and radiolabeled drugs, but was associated with no significant change in brain water. Large shifts in water content in brain slices in vitro caused a small effect on drug penetration. In both cases, total drug permeability increase was greater for lipophilic than hydrophilic compounds. BBBD reduced the amount of free phenytoin in the brain. Discussion:, After BBBD, drug binding to protein is the main controller of total brain drug accumulation. Osmotic BBBD increased serum protein extravasation and reduced free phenytoin brain levels. These results underlie the importance of brain environment and BBB integrity in determining drug distribution to the brain. If confirmed in drug-resistant models, these mechanisms could contribute to drug brain distribution in refractory epilepsies. [source] Drug,Membrane Interaction on Immobilized Liposome Chromatography Compared to Immobilized Artificial Membrane (IAM), Liposome/Water, and Octan-1-ol/Water SystemsHELVETICA CHIMICA ACTA, Issue 2 2010Xiangli Liu Abstract The objective of this study was to investigate drug,membrane interaction by immobilized liposome chromatography (ILC; expressed as lipophilicity index log,Ks) and the comparison with lipophilicity indices obtained by liposome/H2O, octan-1-ol/H2O, and immobilized artificial membrane (IAM) systems. A set of structurally diverse monofunctional compounds and drugs (nonsteroidal anti-inflammatory drugs and , -blockers) were selected in this study. This set of solutes consists of basic or acidic functionalities which are positively or negatively charged at physiological pH,7.4. No correlation was found between log,Ks from ILC and lipophilicity indices from any of the other membrane model systems for the whole set of compounds. For structurally related compounds, significant correlations could be established between log,Ks from ILC and lipophilicity indices from IAM chromatography and octan-1-ol/H2O. However, ILC and liposome/H2O systems only yield parallel partitioning information for structurally related large molecules. For hydrophilic compounds, the balance between electrostatic and hydrophobic interactions dominating drug partitioning is different in these two systems. [source] Influence of composition and structure of oil-in-water emulsions on retention of aroma compoundsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2002Dr Saskia M van Ruth Abstract The influence of the composition and structure of oil-in-water emulsions on aroma retention was examined for 20 volatile compounds. Compositional and structural parameters included the fraction of emulsifier phase, the fraction of lipid phase and the particle size distribution of the dispersed lipid phase in the emulsion. Air/liquid partition coefficients of dimethyl sulphide, 1-propanol, diacetyl, 2-butanone, ethyl acetate, 1-butanol, 2-pentanol, propyl acetate, 3-methyl-1-butanol, ethyl butyrate, hexanal, butyl acetate, 1-hexanol, 2-heptanone, heptanal, ,-pinene, 2-octanone, octanal, 2-nonanol and 2-decanone were determined by static headspace gas chromatography. The hydrophobicity of the compounds determined the influence of the compositional and structural parameters of the emulsions on air/liquid partitioning. Increase of the emulsifier fraction increased the retention of mainly hydrophilic aroma compounds and decreased the retention of hydrophobic compounds. Higher lipid levels led to increased retention of hydrophobic compounds and release of hydrophilic compounds. Emulsions with larger particles showed increased aroma retention, which was independent of the lipid fraction and the polarity of the aroma compounds. The data demonstrated a profound effect of both composition and structure of oil-in-water emulsions on the air/liquid partitioning of the 20 aroma compounds under equilibrium conditions. © 2002 Society of Chemical Industry [source] | ||||||||||||||||