| 1. |
- Ferrari, P., et al.
(författare)
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A bivariate measurement error model for nitrogen and potassium intakes to evaluate the performance of regression calibration in the European Prospective Investigation into Cancer and Nutrition study
- 2009
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 1476-5640 .- 0954-3007. ; 63:4s, s. 179-187
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Within the European Prospective Investigation into Cancer and Nutrition (EPIC) study, the performance of 24-h dietary recall (24-HDR) measurements as reference measurements in a linear regression calibration model is evaluated critically at the individual (within-centre) and aggregate (between-centre) levels by using unbiased estimates of urinary measurements of nitrogen and potassium intakes. Methods: Between 1995 and 1999, 1072 study subjects (59% women) from 12 EPIC centres volunteered to collect 24-h urine samples. Log-transformed questionnaire, 24-HDR and urinary measurements of nitrogen and potassium intakes were analysed in a multivariate measurement error model to estimate the validity of coefficients and error correlations in self-reported dietary measurements. In parallel, correlations between means of 24-HDR and urinary measurements were computed. Linear regression calibration models were used to estimate the regression dilution (attenuation) factors. Results: After adjustment for sex, centre, age, body mass index and height, the validity coefficients for 24-HDRs were 0.285 (95% confidence interval: 0.194, 0.367) and 0.371 (0.291, 0.446) for nitrogen and potassium intakes, respectively. The attenuation factors estimated in a linear regression calibration model were 0.368 (0.228, 0.508) for nitrogen and 0.500 (0.361, 0.639) for potassium intakes; only the former was different from the estimate obtained using urinary measurements in the measurement error model. The aggregate-level correlation coefficients between means of urinary and 24-HDR measurements were 0.838 (0.637, 0.932) and 0.756 (0.481, 0.895) for nitrogen and potassium intakes, respectively. Conclusions: This study suggests that 24-HDRs can be used as reference measurements at the individual and aggregate levels for potassium intake, whereas, for nitrogen intake, good performance is observed for between-centre calibration, but some limitations are apparent at the individual level. European Journal of Clinical Nutrition (2009) 63, S179-S187; doi: 10.1038/ejcn.2009.80
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| 2. |
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| 3. |
- Bamia, Christina, et al.
(författare)
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Dietary patterns and survival of older Europeans : the EPIC-Elderly Study (European Prospective Investigation into Cancer and Nutrition)
- 2007
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Ingår i: Public Health Nutrition. - : Cambridge University Press. - 1368-9800 .- 1475-2727. ; 10:6, s. 590-598
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the association of a posteriori dietary patterns with overall survival of older Europeans.Design and setting: This is a multi-centre cohort study. Cox regression analysis was used to investigate the association of the prevailing, a posteriori-derived, plant-based dietary pattern with all-cause mortality in a population of subjects who were 60 years or older at recruitment to the European Prospective Investigation into Cancer and Nutrition (EPIC-Elderly cohort). Analyses controlled for all known potential risk factors.Subjects: In total, 74 607 men and women, 60 years or older at enrolment and without previous coronary heart disease, stroke or cancer, with complete information about dietary intakes and potentially confounding variables, and with known survival status as of December 2003, were included in the analysis.Results: An increase in the score which measures the adherence to the plant-based diet was associated with a lower overall mortality, a one standard deviation increment corresponding to a statistically significant reduction of 14% (95% confidence interval 5–23%). In country-specific analyses the apparent association was stronger in Greece, Spain, Denmark and The Netherlands, and absent in the UK and Germany.Conclusions: Greater adherence to the plant-based diet that was defined a posteriori in this population of European elders is associated with lower all-cause mortality. This dietary score is moderately positively correlated with the Modified Mediterranean Diet Score that has been constructed a priori and was also shown to be beneficial for the survival of the same EPIC-Elderly cohort.
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| 4. |
- Bolivar, Juan M, et al.
(författare)
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Coating of soluble and immobilized enzymes with ionic polymers : full stabilization of the quaternary structure of multimeric enzymes
- 2009
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:4, s. 742-747
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Tidskriftsartikel (refereegranskat)abstract
- This paper shows a simple and effective way to avoid the dissociation of multimeric enzymes by coating their surface with a large cationic polymer (e.g., polyethylenimine (PEI)) by ionic exchange. As model enzymes, glutamate dehydrogenase (GDH) from Thermus thermophilus and formate dehydrogenase (FDH) from Pseudomonas sp. were used. Both enzymes are very unstable at acidic pH values due to the rapid dissociation of their subunits (half-life of diluted preparations is few minutes at pH 4 and 25 degrees C). GDH and FDH were incubated in the presence of PEI yielding an enzyme-PEI composite with full activity. To stabilize the enzyme-polymer composite, a treatment with glutaraldehyde was required. These enzyme-PEI composites can be crosslinked with glutaraldehyde by immobilizing previously the composite onto a weak cationic exchanger. The soluble GDH-PEI composite was much more stable than unmodified GDH at pH 4 and 30 degrees C (retaining over 90% activity after 24 h incubation) with no effect of the GDH concentration in the inactivation course. The composite could be very strongly, but reversibly, adsorbed on cationic exchangers. Similarly, FDH could be treated with PEI and glutaraldehyde after adsorption on cationic exchangers, This permitted a stabilized FDH preparation. In this way, the coating of the enzymes surfaces with PEI is used as a simple and efficient strategy to prevent enzyme dissociation of multimeric enzymes. These composites can be used as a soluble catalyst or reversibly immobilized onto a cationic exchanger (e.g., CM-agarose).
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| 5. |
- Bolivar, Juan M, et al.
(författare)
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Immobilization-stabilization of a new recombinant glutamate dehydrogenase from Thermus thermophilus
- 2008
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Ingår i: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 0175-7598 .- 1432-0614. ; 80:1, s. 49-58
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Tidskriftsartikel (refereegranskat)abstract
- The genome of Thermus thermophilus contains two genes encoding putative glutamate dehydrogenases. One of these genes (TTC1211) was cloned and overexpressed in Escherichia coli. The purified enzyme was a trimer that catalyzed the oxidation of glutamate to alpha-ketoglutarate and ammonia with either NAD+ or NADP+ as cofactors. The enzyme was also able to catalyze the inverse reductive reaction. The thermostability of the enzyme at neutral pH was very high even at 70 degrees C, but at acidic pH values, the dissociation of enzyme subunits produced the rapid enzyme inactivation even at 25 degrees C. The immobilization of the enzyme on glyoxyl agarose permitted to greatly increase the enzyme stability under all conditions studied. It was found that the multimeric structure of the enzyme was stabilized by the immobilization (enzyme subunits could be not desorbed from the support by boiling it in the presence of sodium dodecyl sulfate). This makes the enzyme very stable at pH 4 (e.g., the enzyme activity did not decrease after 12 h at 45 degrees C) and even improved the enzyme stability at neutral pH values. This immobilized enzyme can be of great interest as a biosensor or as a biocatalyst to regenerate both reduced and oxidized cofactors.
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| 6. |
- Roobol, Monique J., et al.
(författare)
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Prostate Cancer Mortality Reduction by Prostate-Specific Antigen-Based Screening Adjusted for Nonattendance and Contamination in the European Randomised Study of Screening for Prostate Cancer (ERSPC)
- 2009
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Ingår i: European Urology. - : Elsevier BV. - 1873-7560 .- 0302-2838. ; 56:4, s. 584-591
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Tidskriftsartikel (refereegranskat)abstract
- Background: Prostate-specific antigen (PSA) based screening for prostate cancer (PCa) has been shown to reduce prostate specific mortality by 20% in an intention to screen (ITS) analysis in a randomised trial (European Randomised Study of Screening for Prostate Cancer [ERSPC]). This effect may be diluted by nonattendance in men randomised to the screening arm and contamination in men randomised to the control arm. Objective: To assess the magnitude of the PCa-specific mortality reduction after adjustment for nonattendance and contamination. Design, setting, and participants: We analysed the occurrence of PCa deaths during an average follow-up of 9 yr in 162 243 men 55-69 yr of age randomised in seven participating centres of the ERSPC. Centres were also grouped according to the type of randomisation (ie, before or after informed written consent). Intervention: Nonattendance was defined as nonattending the initial screening round in ERSPC. The estimate of contamination was based on PSA use in controls in ERSPC Rotterdam. Measurements: Relative risks (RRs) with 95% confidence intervals (Cis) were compared between an ITS analysis and analyses adjusting for nonattendance and contamination using a statistical method developed for this purpose. Results and limitations: In the ITS analysis, the RR of PCa death in men allocated to the intervention arm relative to the control arm was 0.80 (95% CI, 0.68-0.96). Adjustment for nonattendance resulted in a RR of 0.73 (95% CI, 0.58-0.93), and additional adjustment for contamination using two different estimates led to estimated reductions of 0.69 (95% CI, 0.51-0.92) to 0.71 (95% CI, 0.55-0.93), respectively. Contamination data were obtained through extrapolation of single-centre data. No heterogeneity was found between the groups of centres. Conclusions: PSA screening reduces the risk of dying of PCa by up to 31% in men actually screened. This benefit should be weighed against a degree of over diagnosis and overtreatment inherent in PCa screening. (C) 2009 European Association of Urology. Published by Elsevier B.V. All rights reserved.
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| 7. |
- Schröder, Fritz H, et al.
(författare)
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Screening and prostate-cancer mortality in a randomized European study.
- 2009
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Ingår i: The New England journal of medicine. - 1533-4406 .- 0028-4793. ; 360:13, s. 1320-8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The European Randomized Study of Screening for Prostate Cancer was initiated in the early 1990s to evaluate the effect of screening with prostate-specific-antigen (PSA) testing on death rates from prostate cancer.
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