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241.
Hélène Pereira Jean-François Martin Charlotte Joly Jean-Louis Sébédio Estelle Pujos-Guillot 《Metabolomics : Official journal of the Metabolomic Society》2010,6(2):207-218
In order to study the effect of a diet on metabolites found in body fluids such as plasma, we have developed and validated
a UPLC/MS method. While methods using NMR have been well established to analyse different biological tissues, recent studies
have described robust untargeted UPLC-MS methods for plasma analysis. One major concern when profiling plasma is the presence
of an important quantity of proteins which have to be precipitated without any loss of metabolites prior to LC/MS analysis.
The utilization of untargeted approaches in nutritional metabolomics still suffers from the lack of identification of specific
biomarkers. We therefore suggest an alternative method still using a global approach but focusing at the same time on metabolites
previously described in human plasma in order to detect biomarkers of metabolic dysregulations. Thus, to fulfil our objectives,
analytical parameters were tested (i) the anticoagulant type for sample collection, (ii) the protein precipitation method
and (iii) UPLC/MS analytical conditions. Three protein precipitation methods and two anticoagulants were tested and compared.
The method utilizing blood collection on heparin and methanol precipitation was chosen for giving the most reproducible results
while keeping the complexity of the sample. Finally, a validation was proposed to evaluate the stability of this analytical
method applied to a large batch of samples for nutritional metabolomic studies. 相似文献
242.
Transient receptor potential ion channel melastatin subtype 8 (TRPM8) is activated by cold temperature and cooling agents,
such as menthol and icilin. Compounds containing peppermint are reported to reduce symptoms of environmental cold stress such
as cold allodynia in dorsal root ganglion (DRG) neuron; however, the underlying mechanisms of action are unclear. We tested
the effects of physiological heat (37°C), anthralic acid (ACA and 0.025 mM), 2-aminoethyl diphenylborinate (2-APB and 0.05)
on noxious cold (10°C) and menthol (0.1 mM)-induced TRPM8 cation channel currents in the DRG neurons of rats. DRG neurons
were freshly isolated from rats. In whole-cell patch clamp experiments, TRPM8 currents were consistently induced by noxious
cold or menthol. TRPM8 channels current densities of the neurons were higher in cold and menthol groups than in control. When
the physiological heat is introduced by chamber TRPM8 channel currents were inhibited by the heat. Noxious cold-induced Ca2+ gates were blocked by the ACA although menthol-induced TRPM8 currents were not blocked by ACA and 2-APB. In conclusion, the
results suggested that activation of TRPM8 either by menthol or nociceptive cold can activate TRPM8 channels although we observed
the protective role of heat, ACA and 2-APB through a TRPM8 channel in nociceptive cold-activated DRG neurons. Since cold allodynia
is a common feature of neuropathic pain and diseases of sensory neuron, our findings are relevant to the etiology of neuropathology
in DRG neurons. 相似文献
243.
Leppänen J Huuskonen J Savolainen J Nevalainen T Taipale H Vepsäläinen J Gynther J Järvinen T 《Bioorganic & medicinal chemistry letters》2000,10(17):1967-1969
Entacapone was reacted with phosphorous oxychloride in dry pyridine to yield a phosphate ester. The phosphate promoiety increased aqueous solubility of the parent drug by more than 1700- and 20-fold at pH 1.2 and 7.4, respectively. The phosphate ester provides adequate stability (t(1/2) = 2227 h; pH 7.4) towards chemical hydrolysis, and allowed for release of the parent drug via enzymatic hydrolysis in liver homogenate. 相似文献
244.
Pregnane X receptor-agonists down-regulate hepatic ATP-binding cassette transporter A1 and scavenger receptor class B type I 总被引:4,自引:0,他引:4
Sporstøl M Tapia G Malerød L Mousavi SA Berg T 《Biochemical and biophysical research communications》2005,331(4):1533-1541
Pregnane X receptor (PXR) is the molecular target for a wide variety of endogenous and xenobiotic compounds. It regulates the expression of genes central to the detoxification (cytochrome P-450 enzymes) and excretion (xenobiotic transporters) of potentially harmful compounds. The aim of the present investigation was to determine the role of PXR in regulation of high-density lipoprotein (HDL) cholesterol metabolism by studying its impact on ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) expression in hepatocytes. ABCA1 and SR-BI are major factors in the exchange of cholesterol between cells and HDL. Expression analyses were performed using Western blotting and quantitative real time RT-PCR. Luciferase reporter gene assays were used to measure promoter activities. Total cholesterol was measured enzymatically after lipid extraction (Folch's method). The expression of ABCA1 and SR-BI was inhibited by the PXR activators rifampicin and lithocholic acid (LCA) in HepG2 cells and pregnenolone 16alpha-carbonitrile (PCN) in primary rat hepatocytes. Thus, PXR appears to be a regulator of hepatic cholesterol transport by inhibiting genes central to cholesterol uptake (SR-BI) and efflux (ABCA1). 相似文献
245.
246.
Spatial mismatch in morphological,ecological and phylogenetic diversity,in historical and contemporary European freshwater fish faunas 下载免费PDF全文
Lucie Kuczynski Jessica Côte Aurèle Toussaint Sébastien Brosse Laëtitia Buisson Gaël Grenouillet 《Ecography》2018,41(10):1665-1674
Biodiversity encompasses multiple facets, among which taxonomic, functional and phylogenetic aspects are the most often considered. Understanding how those diversity facets are distributed and what are their determinants has become a central concern in the current context of biodiversity crisis, but such multi‐faceted measures over large geographical areas are still pending. Here, we measured the congruence between the biogeographical patterns of freshwater fish morphological, ecological and phylogenetic diversity across Europe and identified the natural and anthropogenic drivers shaping those patterns. Based on freshwater fish occurrence records in 290 European river catchments, we computed richness and evenness for morphological, ecological and phylogenetic diversity using standardized effect sizes for each diversity index. We then used linear models including climatic, geo‐morphological, biotic and human‐related factors to determine the key drivers shaping freshwater fish biodiversity patterns across Europe. We found a weak spatial congruence between facets of diversity. Patterns of diversity were mainly driven by elevation range, climatic seasonality and species richness while other factors played a minor role. Finally, we found that non‐native species introductions significantly affected diversity patterns and influenced the effects of some environmental drivers. Morphological, ecological and phylogenetic diversity constitute complementary facets of fish diversity rather than surrogates, testifying that they deserve to be considered altogether to properly assess biodiversity. Although the same environmental and anthropogenic factors overall explained those diversity facets, their relative influence varied. In the current context of global change, non‐native species introductions may also lead to important reshuffling of assemblages resulting in profound changes of diversity patterns. 相似文献
247.
248.
249.
Carlier L Couprie J le Maire A Guilhaudis L Milazzo-Segalas I Courçon M Moutiez M Gondry M Davoust D Gilquin B Zinn-Justin S 《Protein science : a publication of the Protein Society》2007,16(12):2750-2755
Human KIN17 is a 45-kDa eukaryotic DNA- and RNA-binding protein that plays an important role in nuclear metabolism and in particular in the general response to genotoxics. Its amino acids sequence contains a zinc finger motif (residues 28-50) within a 30-kDa N-terminal region conserved from yeast to human, and a 15-kDa C-terminal tandem of SH3-like subdomains (residues 268-393) only found in higher eukaryotes. Here we report the solution structure of the region 51-160 of human KIN17. We show that this fragment folds into a three-alpha-helix bundle packed against a three-stranded beta-sheet. It belongs to the winged helix (WH) family. Structural comparison with analogous WH domains reveals that KIN17 WH module presents an additional and highly conserved 3(10)-helix. Moreover, KIN17 WH helix H3 is not positively charged as in classical DNA-binding WH domains. Thus, human KIN17 region 51-160 might rather be involved in protein-protein interaction through its conserved surface centered on the 3(10)-helix. 相似文献
250.
Mariëtte van Amstel Claar de Brauw Peter Driessen Pieter Glasbergen 《Biodiversity and Conservation》2007,16(14):4109-4129
This paper seeks to understand why multinationals prefer to launch a label specific to their own product and examines how
reliable these product-specific eco-labels are. A new methodology is applied to assess the extent to which eco-labels live
up to claims about their contribution to conservation and the sustainable use of agricultural biodiversity. Product-specific
eco-labels are considered as industry self-regulation and all three regulatory stages are studied: the planning, implementation
and outcome stage. There are major differences between the product specific eco-labels in the degree in which agrobiodiversity
management is part of the normative labeling schemes. Although there are some problems of reliability, such as transparency
in the implementation stage and the monitoring in the outcome stage, the degree of reliability of product-specific labels
is comparable with eco-labels of international labeling families. The conclusion is that only one of the product-specific
eco-labels examined here is reliable when examined in the light of all three stages. The main reason why multinationals establish
a product-specific eco-label instead of adopting one from an existing labeling family is that they want to profile themselves
as distinct from other companies. The unique character of a product-specific label creates a market opportunity for them. 相似文献