3,225 research outputs found

    Application of Cryopreserved Human Hepatocytes in Trichloroethylene Risk Assessment: Relative Disposition of Chloral Hydrate to Trichloroacetate and Trichloroethanol

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    BACKGROUND: Trichloroethylene (TCE) is a suspected human carcinogen and a common ground-water contaminant. Chloral hydrate (CH) is the major metabolite of TCE formed in the liver by cytochrome P450 2E1. CH is metabolized to the hepatocarcinogen trichloroacetate (TCA) by aldehyde dehydrogenase (ALDH) and to the noncarcinogenic metabolite trichloroethanol (TCOH) by alcohol dehydrogenase (ADH). ALDH and ADH are polymorphic in humans, and these polymorphisms are known to affect the elimination of ethanol. It is therefore possible that polymorphisms in CH metabolism will yield subpopulations with greater than expected TCA formation with associated enhanced risk of liver tumors after TCE exposure. METHODS: The present studies were undertaken to determine the feasibility of using commercially available, cryogenically preserved human hepatocytes to determine simultaneously the kinetics of CH metabolism and ALDH/ADH genotype. Thirteen human hepatocyte samples were examined. Linear reciprocal plots were obtained for 11 ADH and 12 ALDH determinations. RESULTS: There was large interindividual variation in the V(max) values for both TCOH and TCA formation. Within this limited sample size, no correlation with ADH/ALDH genotype was apparent. Despite the large variation in V(max) values among individuals, disposition of CH into the two competing pathways was relatively constant. CONCLUSIONS: These data support the use of cryopreserved human hepatocytes as an experimental system to generate metabolic and genomic information for incorporation into TCE cancer risk assessment models. The data are discussed with regard to cellular factors, other than genotype, that may contribute to the observed variability in metabolism of CH in human liver

    The cluster Abell 780: an optical view

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    The Abell 780 cluster, better known as the Hydra A cluster, has been thouroughly analyzed in X-rays. However, little is known on its optical properties. We derive the galaxy luminosity function (GLF) in this apparently relaxed cluster, and search for possible environmental effects by comparing the GLFs in various regions, and by looking at the galaxy distribution at large scale around Abell 780. Our study is based on optical images obtained with the ESO 2.2m telescope and WFI camera in the B and R bands, covering a total region of 67.22x32.94 arcmin^2, or 4.235x2.075 Mpc^2 for a cluster redshift of 0.0539. In a region of 500 kpc radius around the cluster centre, the GLF in the R band shows a double structure, with a broad and flat bright part and a flat faint end that can be fit by a power law with an index alpha=-0.85+-0.12 in the 20.25<R<21.75 interval. If we divide this 500 kpc radius region in North+South or East+West halves, we find no clear difference between the GLFs in these smaller regions. No obvious large scale structure is apparent within 5 Mpc from the cluster, based on galaxy redshifts and magnitudes collected from the NED database in a much larger region than that covered by our data, suggesting that there is no major infall of material in any preferential direction. However, the Serna-Gerbal method reveals the presence of a gravitationally bound structure of 27 galaxies, which includes the cD, and of a more strongly gravitationally bound structure of 14 galaxies. These optical results agree with the overall relaxed structure of Abell 780 previously derived from X-ray analyses.Comment: Accepted for publication in Astronomy & Astrophysic

    Catalytic enantioselective stereoablative reactions: an unexploited approach to enantioselective catalysis

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    Approaches to the preparation of enantioenriched materials via catalytic methods that destroy stereogenic elements of a molecule are discussed. Although these processes often decrease overall molecular complexity, there are several notable advantages including material recycling, enantiodivergence and convergence, and increased substrate scope. Examples are accompanied by discussion of the critical design elements required for the success of these methods

    Public Response to Cost-Quality Tradeoffs in Clinical Decisions.

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    PURPOSE: To explore public attitudes toward the incorporation of cost-effectiveness analysis into clinical decisions. METHODS: The authors presented 781 jurors with a survey describing 1 of 6 clinical encounters in which a physician has to choose between cancer screening tests. They provided cost-effectiveness data for all tests, and in each scenario, the most effective test was more expensive. They instructed respondents to imagine that he or she was the physician in the scenario and asked them to choose which test to recommend and then explain their choice in an open-ended manner. The authors then qualitatively analyzed the responses by identifying themes and developed a coding scheme. Two authors separately coded the statements with high overall agreement (kappa = 0.76). Categories were not mutually exclusive. RESULTS: Overall, 410 respondents (55%) chose the most expensive option, and 332 respondents (45%) choose a less expensive option. Explanatory comments were given by 82% respondents. Respondents who chose the most expensive test focused on the increased benefit (without directly acknowledging the additional cost) (39%), a general belief that life is more important than money (22%), the significance of cancer risk for the patient in the scenario (20%), the belief that the benefit of the test was worth the additional cost (8%), and personal anecdotes/preferences (6%). Of the respondents who chose the less expensive test, 40% indicated that they did not believe that the patient in the scenario was at significant risk for cancer, 13% indicated that they thought the less expensive test was adequate or not meaningfully different from the more expensive test, 12% thought the cost of the test was not worth the additional benefit, 9% indicated that the test was too expensive (without mention of additional benefit), and 7% responded that resources were limited. CONCLUSIONS: Public response to cost-quality tradeoffs is mixed. Although some respondents justified their decision based on the cost-effectiveness information provided, many focused instead on specific features of the scenario or on general beliefs about whether cost should be incorporated into clinical decisions

    Measuring the Cluster Magnetic Field Power Spectra from Faraday Rotation Maps of Abell 400, Abell 2634 and Hydra A

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    We apply a novel technique of Faraday Rotation measure (RM) map analysis to three galaxy clusters, Abell 400, Abell 2634 and Hydra A, in order to estimate cluster magnetic field strengths, length scales and power spectra. This analysis is based on the assumption that the magnetic fields are statistically isotropically distributed across the Faraday screen. We investigate the difficulties involved in the application of the analysis to observational data. We derive magnetic power spectra for the three clusters and discuss influences on their shapes. We show that magnetic fluctuations are probed on length scales ranging over at least one order of magnitude. Using this range for the determination of central cluster magnetic field strength yields 3 muG in Abell 2634, 6 muG in Abell 400 and 12 muG in Hydra A. The magnetic field autocorrelation length was determined to be 4.9 kpc for Abell 2634, 3.6 kpc for Abell 400 and 0.9 kpc for Hydra A. We show that the RM autocorrelation length is larger than the magnetic field autocorrelation length. We investigate in a response analysis if it is possible to determine spectral slopes of the power spectra. We find that integrated numbers can be determined from this analysis but differential parameters such as spectral slopes have to be treated differently. Our response analysis results in spectral slopes of the power spectra of spectral indices alpha = 1.6 to 2.0 suggesting that Kolmogorov spectra are possible but flatter spectral slopes than alpha = 1.3 can be excluded.Comment: 14 pages, 9 figures, accepted by A&

    Predicting Symptoms of Depression and Anxiety Using Smartphone and Wearable Data

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    Background: Depression and anxiety are leading causes of disability worldwide but often remain undetected and untreated. Smartphone and wearable devices may offer a unique source of data to detect moment by moment changes in risk factors associated with mental disorders that overcome many of the limitations of traditional screening methods. Objective: The current study aimed to explore the extent to which data from smartphone and wearable devices could predict symptoms of depression and anxiety. Methods: A total of N = 60 adults (ages 24-68) who owned an Apple iPhone and Oura Ring were recruited online over a 2-week period. At the beginning of the study, participants installed the Delphi data acquisition app on their smartphone. The app continuously monitored participants' location (using GPS) and smartphone usage behavior (total usage time and frequency of use). The Oura Ring provided measures related to activity (step count and metabolic equivalent for task), sleep (total sleep time, sleep onset latency, wake after sleep onset and time in bed) and heart rate variability (HRV). In addition, participants were prompted to report their daily mood (valence and arousal). Participants completed self-reported assessments of depression, anxiety and stress (DASS-21) at baseline, midpoint and the end of the study. Results: Multilevel models demonstrated a significant negative association between the variability of locations visited and symptoms of depression (beta = -0.21, p = 0.037) and significant positive associations between total sleep time and depression (beta = 0.24, p = 0.023), time in bed and depression (beta = 0.26, p = 0.020), wake after sleep onset and anxiety (beta = 0.23, p = 0.035) and HRV and anxiety (beta = 0.26, p = 0.035). A combined model of smartphone and wearable features and self-reported mood provided the strongest prediction of depression. Conclusion: The current findings demonstrate that wearable devices may provide valuable sources of data in predicting symptoms of depression and anxiety, most notably data related to common measures of sleep.Peer reviewe

    Telephone-administered psychotherapy for depression in MS patients: moderating role of social support

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    Depression is common in individuals with multiple sclerosis (MS). While psychotherapy is an effective treatment for depression, not all individuals benefit. We examined whether baseline social support might differentially affect treatment outcome in 127 participants with MS and depression randomized to either Telephone-administered Cognitive-Behavioral Therapy (T-CBT) or Telephone-administered Emotion-Focused Therapy (T-EFT). We predicted that those with low social support would improve more in T-EFT, since this approach emphasizes the therapeutic relationship, while participants with strong social networks and presumably more emotional resources might fare better in the more structured and demanding T-CBT. We found that both level of received support and satisfaction with that support at baseline did moderate treatment outcome. Individuals with high social support showed a greater reduction in depressive symptoms in the T-CBT as predicted, but participants with low social support showed a similar reduction in both treatments. This suggests that for participants with high social support, CBT may be a more beneficial treatment for depression compared with EFT
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