370 research outputs found

    The effects of climatic warming on the phenology of Arctic plants and their principal herbivore

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    There is mounting evidence that many plants and animals may be unable to adjust the timing of their various life cycle events rapidly enough to adjust to predicted rates of climate change. For example, the close synchronisation between bud-burst and herbivore emergence may be disrupted by increased temperatures. However, many experimental studies demonstrating these effects have only used short term temperature manipulations, despite the possibility that strong selection pressure could lead to rapid adaptation to a changing climate over several years. This study therefore investigated whether phenological synchrony between plants and their herbivores was disrupted after five years of simulated climate change. A series of warming chambers was set up across the forest-tundra ecotone in Arctic Sweden. The chambers increased temperatures relative to control plots in line with average predictions from climate change models. The warming chambers did not affect the timing of snow melt, suggesting that hydrological conditions were broadly similar in warming chambers and control plots. Plants growing in areas with a late-melting snow pack showed accelerated development and growth in comparison with plants in early-melting areas, so that plants in all areas completed development at about the same time. However, invertebrate herbivores were more closely synchronised to their host plants in areas where immature foliage was only available for a short period of time. Experimental warming advanced the onset of leaf development and also increased the area of leaf tissue available to herbivores. However, phenological synchrony between invertebrate herbivores and their host plants was not affected by warming, as the lag between leaf emergence and the onset of herbivory was similar in warming chambers and control plots. This suggests that herbivores may be able to respond relatively rapidly to changes in host plant phenology. However, elevated temperatures were associated with an increase in defoliation, with potentially severe consequences for the birch forests of northern Fennoscandia

    Stereoselective pharmacokinetics of stable isotope (+/-)-[13C]-pantoprazole: Implications for a rapid screening phenotype test of CYP2C19 activity

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    AIMS: We have previously shown that the (±)-[(13) C]-pantoprazole breath test is a promising noninvasive probe of CYP2C19 activity. As part of that trial, plasma, breath test indices and CYP2C19 (*2, *3, and *17) genotype were collected. Here, we examined whether [(13) C]-pantoprazole exhibits enantioselective pharmacokinetics and whether this enantioselectivity is correlated with indices of breath test. METHODS: Plasma (-)- and (+)-[(13) C]-pantoprazole that were measured using a chiral HPLC were compared between CYP2C19 genotypes and correlated with breath test indices. RESULTS: The AUC( 0-∞) of (+)-[(13) C]-pantoprazole in PM (*2/*2, n = 4) was 10.1- and 5.6-fold higher that EM (*1/*1or *17, n = 10) and IM (*1/*2or *3, n = 10) of CYP2C19, respectively (P < 0.001). The AUC( 0-∞) of (-)-[(13) C]-pantoprazole only significantly differed between PMs and EMs (1.98-fold; P = 0.05). The AUC( 0-∞) ratio of (+)-/(-)-[(13) C]-pantoprazole was 3.45, 0.77, and 0.67 in PM, IM, and EM genotypes, respectively. Breath test index, delta over baseline show significant correlation with AUC( 0-∞) of (+)-[(13) C]-pantoprazole (Pearson's r = 0.62; P < 0.001). CONCLUSIONS: [(13) C]-pantoprazole exhibits enantioselective elimination. (+)-[(13) C]-pantoprazole is more dependent on CYP2C19 metabolic status and may serve as a more attractive probe of CYP2C19 activity than (-)-[(13) C]-pantoprazole or the racemic mixture

    Two-axis bend measurement with Bragg gratings in multicore optical fiber

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    We describe what is to our knowledge the first use of fiber Bragg gratings written into three separate cores of a multicore fiber for two-axis curvature measurement. The gratings act as independent, but isothermal, fiber strain gauges for which local curvature determines the difference in strain between cores, permitting temperature-independent bend measurement. (C) 2003 Optical Society of America

    Pharmacogenetic variants influence tamoxifen's estrogenic effect on bone density

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109849/1/cptclpt200586.pd

    Identification and Mechanistic Investigation of Drug-Drug Interactions Associated With Myopathy: A Translational Approach

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    Myopathy is a group of muscle diseases that can be induced or exacerbated by drug-drug interactions (DDIs). We sought to identify clinically important myopathic DDIs and elucidate their underlying mechanisms. Five DDIs were found to increase the risk of myopathy based on analysis of observational data from the Indiana Network of Patient Care. Loratadine interacted with simvastatin (relative risk 95% confidence interval [CI] = [1.39, 2.06]), alprazolam (1.50, 2.31), ropinirole (2.06, 5.00), and omeprazole (1.15, 1.38). Promethazine interacted with tegaserod (1.94, 4.64). In vitro investigation showed that these DDIs were unlikely to result from inhibition of drug metabolism by CYP450 enzymes or from inhibition of hepatic uptake via the membrane transporter OATP1B1/1B3. However, we did observe in vitro synergistic myotoxicity of simvastatin and desloratadine, suggesting a role in loratadine-simvastatin interaction. This interaction was epidemiologically confirmed (odds ratio 95% CI = [2.02, 3.65]) using the data from the US Food and Drug Administration Adverse Event Reporting System

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109873/1/cptclpt2006159.pd
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