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1.
The separation and quantitation of coumarinic anticoagulant drug enantiomers were achieved by direct chiral capillary electrophoresis using complex maltooligosaccharide mixtures as stereoselective electrolyte modifiers. Chiral separations were characterized by a high selectivity and efficiency, enabling enantiomeric excess determinations. In addition, preliminary results indicate the applicability of the method for the determination of individual enantiomers in biological samples. So the method can be used to perform stereoselective pharmacokinetic studies. © 1994 Wiley-Liss, Inc. 相似文献
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Summary A class of nonignorable models is presented for handling nonmonotone missingness in categorical longitudinal responses. This class of models includes the traditional selection models and shared parameter models. This allows us to perform a broader than usual sensitivity analysis. In particular, instead of considering variations to a chosen nonignorable model, we study sensitivity between different missing data frameworks. An appealing feature of the developed class is that parameters with a marginal interpretation are obtained, while algebraically simple models are considered. Specifically, marginalized mixed‐effects models ( Heagerty, 1999 , Biometrics 55, 688–698) are used for the longitudinal process that model separately the marginal mean and the correlation structure. For the correlation structure, random effects are introduced and their distribution is modeled either parametrically or non‐parametrically to avoid potential misspecifications. 相似文献
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Verbeke TJ Dumonceaux TJ Wushke S Cicek N Levin DB Sparling R 《FEMS microbiology ecology》2011,78(3):473-487
In this study, 12 strains of Thermoanaerobacter were isolated from a single decaying wood compost sample and subjected to genetic and phenotypic profiling. The 16S rRNA encoding gene sequences suggested that the isolates were most similar to strains of either Thermoanaerobacter pseudethanolicus or Thermoanaerobacter thermohydrosulfuricus. Examination of the lesser conserved chaperonin-60 (cpn60) universal target showed that some isolates shared the highest sequence identity with T.?thermohydrosulfuricus; however, others to Thermoanaerobacter wiegelii and Thermoanaerobacter sp. Rt8.G4 (formerly Thermoanaerobacter brockii Rt8.G4). BOX-PCR fingerprinting profiles identified differences in the banding patterns not only between the isolates and the reference strains, but also among the isolates themselves. To evaluate the extent these genetic differences were manifested phenotypically, the utilization patterns of 30 carbon substrates were examined and the niche overlap indices (NOI) calculated. Despite showing a high NOI (>?0.9), significant differences existed in the substrate utilization capabilities of the isolates suggesting that either a high degree of niche specialization or mechanisms allowing for non-competitive co-existence, were present within this ecological context. Growth studies showed that the isolates were physiologically distinct in both growth rate and the fermentation product ratios. Our data indicate that phenotypic diversity exists within genetically microdiverse Thermoanaerobacter isolates from a common environment. 相似文献
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Distribution of the major light-harvesting chlorophyll a/b-protein (LHCII) and its mRNA within bundle sheath and mesophyll cells of maize (Zea mays L.) was studied using in situ immunolocalization and hybridization, respectively. In situ hybridization with specific LHCII RNA probes from maize and Lemna gibba definitively shows the presence of high levels of mRNA for LHCII in both bundle sheath cells and mesophyll cells. In situ immuno-localization studies, using an LHCII monoclonal antibody, demonstrate the presence of LHCII polypeptides in chloroplasts of both cell types. The polypeptide composition of LHCII and the amount of LHCII in bundle sheath cells are different from those in mesophyll cells. Both mesophyll and bundle sheath chloroplasts can take up, import and process the in vitro transcribed and translated LHCII precursor protein from L. gibba. Although bundle sheath chloroplasts incorporate LHCII into the pigmented light-harvesting complex, the efficiency is lower than that in mesophyll chloroplasts. 相似文献
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Zbigniew Lazar Tristan Rossignol Jonathan Verbeke Anne-Marie Crutz-Le Coq Jean-Marc Nicaud Małgorzata Robak 《Journal of industrial microbiology & biotechnology》2013,40(11):1273-1283
Yarrowia lipolytica requires the expression of a heterologous invertase to grow on a sucrose-based substrate. This work reports the construction of an optimized invertase expression cassette composed of Saccharomyces cerevisiae Suc2p secretion signal sequence followed by the SUC2 sequence and under the control of the strong Y. lipolytica pTEF promoter. This new construction allows a fast and optimal cleavage of sucrose into glucose and fructose and allows cells to reach the maximum growth rate. Contrary to pre-existing constructions, the expression of SUC2 is not sensitive to medium composition in this context. The strain JMY2593, expressing this new cassette with an optimized secretion signal sequence and a strong promoter, produces 4,519 U/l of extracellular invertase in bioreactor experiments compared to 597 U/l in a strain expressing the former invertase construction. The expression of this cassette strongly improved production of invertase and is suitable for simultaneously high production level of citric acid from sucrose-based media. 相似文献
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De Schutter Kristof Verbeke Isabel Kontogiannatos Dimitriοs Dubruel Peter Swevers Luc Van Damme Els J. M. Smagghe Guy 《In vitro cellular & developmental biology. Plant》2022,58(4):511-520
In Vitro Cellular & Developmental Biology - Plant - While RNAi approaches based on transgenic plants overexpressing double-stranded RNAs (dsRNAs) have yielded a number of genetically modified... 相似文献
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Geboes KP De Preter V Luypaerts A Bammens B Evenepoel P Ghoos Y Rutgeerts P Verbeke K 《American journal of physiology. Gastrointestinal and liver physiology》2005,288(5):G994-G999
In vitro experiments have shown that fermentation of carbohydrates prevents accumulation of nitrogen in the colon. Variable results have been obtained on modulation of dietary intakes in vivo. Lactose[15N,15N]-labeled ureide has been proposed as a tool to study colonic nitrogen metabolism. However, on oral administration of the marker, different urinary excretion patterns of the 15N label have been found. In this study, 50 mg lactose[15N,15N]ureide was directly instilled in the colon through an orocecal tube to investigate the colonic handling of this molecule in a direct way. In basal conditions, 42% (range, 37-48%) of labeled nitrogen administered as lactose[15N,15N]ureide was retrieved in urine after 72 h. A substantial variability in total urinary excretion of the label was found, but the urinary excretion pattern of the label was similar in all volunteers. When inulin, a fermentable carbohydrate, was administered together with the labeled marker, a significant decrease in urinary excretion of 15N after 72 h was found, to 29% (range, 23-34%). The effect of a smaller dose of inulin (250 mg) on colonic handling of lactose[15N,15N]ureide (50 mg), was investigated in another group of volunteers, and this time, fecal excretion of the marker was also evaluated. The results seem to indicate that fermentation of inulin causes an increased fecal excretion of the marker, thereby reducing urinary excretion but not retention in the human nitrogen pool. This instillation study shows that lactose[15N,15N]ureide is a tool with good properties to investigate the effect of different types of carbohydrates on nitrogen metabolism in the proximal colon in vivo. 相似文献
10.
Colette?Kanellopoulos-LangevinEmail author Stéphane?M?Caucheteux Philippe?Verbeke David?M?Ojcius 《Reproductive biology and endocrinology : RB&E》2003,1(1):121
The adaptive immune system of placental mammals has evolved to tolerate the fetus. Rejection of the fetus by adaptive immune
responses is therefore a rare event, with abortion being caused more frequently by inflammation in the placenta. This review
will cover recent aspects of immune privilege and the innate immune system at the feto-maternal interface, citing examples
of the role played by microbial infections in fetal demise. 相似文献