| 1. |
- Emerging Risk Factors, Collaboration, et al.
(författare)
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The Emerging Risk Factors Collaboration: analysis of individual data on lipid, inflammatory and other markers in over 1.1 million participants in 104 prospective studies of cardiovascular diseases
- 2007
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Ingår i: Eur J Epidemiol. - 0393-2990. ; 22:12, s. 839-69
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Tidskriftsartikel (refereegranskat)abstract
- Many long-term prospective studies have reported on associations of cardiovascular diseases with circulating lipid markers and/or inflammatory markers. Studies have not, however, generally been designed to provide reliable estimates under different circumstances and to correct for within-person variability. The Emerging Risk Factors Collaboration has established a central database on over 1.1 million participants from 104 prospective population-based studies, in which subsets have information on lipid and inflammatory markers, other characteristics, as well as major cardiovascular morbidity and cause-specific mortality. Information on repeat measurements on relevant characteristics has been collected in approximately 340,000 participants to enable estimation of and correction for within-person variability. Re-analysis of individual data will yield up to approximately 69,000 incident fatal or nonfatal first ever major cardiovascular outcomes recorded during about 11.7 million person years at risk. The primary analyses will involve age-specific regression models in people without known baseline cardiovascular disease in relation to fatal or nonfatal first ever coronary heart disease outcomes. This initiative will characterize more precisely and in greater detail than has previously been possible the shape and strength of the age- and sex-specific associations of several lipid and inflammatory markers with incident coronary heart disease outcomes (and, secondarily, with other incident cardiovascular outcomes) under a wide range of circumstances. It will, therefore, help to determine to what extent such associations are independent from possible confounding factors and to what extent such markers (separately and in combination) provide incremental predictive value.
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| 2. |
- van Gils, C H, et al.
(författare)
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Consumption of vegetables and fruits and risk of breast cancer
- 2005
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Ingår i: JAMA: The Journal of the American Medical Association. - 1538-3598. ; 293:2, s. 183-193
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Tidskriftsartikel (refereegranskat)abstract
- Context The intake of vegetables and fruits has been thought to protect against breast cancer. Most of the evidence comes from case-control studies, but a recent pooled analysis of the relatively few published cohort studies suggests no significantly reduced breast cancer risk is associated with vegetable and fruit consumption. Objective To examine the relation between total and specific vegetable and fruit intake and the incidence of breast cancer. Design, Setting, and Participants Prospective study of 285526 women between the ages of 25 and 70 years, participating in the European Prospective Investigation Into Cancer and Nutrition (EPIC) study, recruited from 8 of the 10 participating European countries. Participants completed a dietary questionnaire in 1992-1998 and were followed up for incidence of cancer until 2002. Main Outcome Measures Relative risks for breast cancer by total and specific vegetable and fruit intake. Analyses were stratified by age at recruitment and study center. Relative risks were adjusted for established breast cancer risk factors. Results During 1486402 person-years (median duration of follow-up, 5.4 years), 3659 invasive incident breast cancer cases were reported. No significant associations between vegetable or fruit intake and breast cancer risk were observed. Relative risks for the highest vs the lowest quintile were 0.98 (95% confidence interval [CI], 0.84-1.14) for total vegetables, 1.09 (95% Cl, 0.94-1.25) for total fruit, and 1.05 (95% Cl, 0.92-1.20) for fruit and vegetable juices. For 6 specific vegetable subgroups no associations with breast cancer risk were observed either. Conclusion Although the period of follow-up is limited for now, the results suggest that total or specific vegetable and fruit intake is not associated with risk for breast cancer.
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| 3. |
- Weikert, S, et al.
(författare)
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Blood Pressure and Risk of Renal Cell Carcinoma in the European Prospective Investigation into Cancer and Nutrition
- 2008
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Ingår i: American Journal of Epidemiology. - : Oxford University Press (OUP). - 0002-9262 .- 1476-6256. ; 167:4, s. 438-446
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Tidskriftsartikel (refereegranskat)abstract
- Elevated blood pressure has been implicated as a risk factor for renal cell carcinoma (RCC), but prospective studies were confined to men and did not consider the effect of antihypertensive medication. The authors examined the relation among blood pressure, antihypertensive medication, and RCC in the European Prospective Investigation into Cancer and Nutrition (EPIC). Blood pressure was measured in 296,638 women and men, recruited in eight European countries during 1992-1998, 254,935 of whom provided information on antihypertensive medication. During a mean follow-up of 6.2 years, 250 cases of RCC were identified. Blood pressure was independently associated with risk of RCC. The relative risks for the highest versus the lowest category of systolic (>/=160 mmHg vs. <120 mmHg) and diastolic (>/=100 mmHg vs. <80 mmHg) blood pressures were 2.48 (95% confidence interval: 1.53, 4.02) and 2.34 (95% confidence interval: 1.54, 3.55). Risk estimates did not significantly differ according to sex or use of antihypertensive medication. Individuals taking antihypertensive drugs were not at a significantly increased risk unless blood pressure was poorly controlled. These results support the hypothesis that hypertension, rather than its medications, increases the risk of RCC in both sexes, while effective blood pressure control may lower the risk.
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| 4. |
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| 5. |
- Allen, N. E., et al.
(författare)
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Animal foods, protein, calcium and prostate cancer risk: the European Prospective Investigation into Cancer and Nutrition
- 2008
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 98:9, s. 1574-1581
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Tidskriftsartikel (refereegranskat)abstract
- We examined consumption of animal foods, protein and calcium in relation to risk of prostate cancer among 142 251 men in the European Prospective Investigation into Cancer and Nutrition. Associations were examined using Cox regression, stratified by recruitment centre and adjusted for height, weight, education, marital status and energy intake. After an average of 8.7 years of follow-up, there were 2727 incident cases of prostate cancer, of which 1131 were known to be localised and 541 advanced-stage disease. A high intake of dairy protein was associated with an increased risk, with a hazard ratio for the top versus the bottom fifth of intake of 1.22 (95% confidence interval (CI): 1.07-1.41, P-trend = 0.02). After calibration to allow for measurement error, we estimated that a 35-g day(-1) increase in consumption of dairy protein was associated with an increase in the risk of prostate cancer of 32% (95% CI: 1-72%, P-trend = 0.04). Calcium from dairy products was also positively associated with risk, but not calcium from other foods. The results support the hypothesis that a high intake of protein or calcium from dairy products may increase the risk for prostate cancer.
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| 6. |
- Jenab, M, et al.
(författare)
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Plasma and dietary carotenoid, retinol and tocopherol levels and the risk of gastric adenocarcinomas in the European prospective investigation into cancer and nutrition
- 2006
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 1532-1827 .- 0007-0920. ; 95:3, s. 406-415
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Tidskriftsartikel (refereegranskat)abstract
- Despite declining incidence rates, gastric cancer (GC) is a major cause of death worldwide. Its aetiology may involve dietary antioxidant micronutrients such as carotenoids and tocopherols. The objective of this study was to determine the association of plasma levels of seven common carotenoids, their total plasma concentration, retinol and alpha- and gamma-tocopherol, with the risk of gastric adenocarcinoma in a case-control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 countries. A secondary objective was to determine the association of total sum of carotenoids, retinol and alpha-tocopherol on GCs by anatomical subsite (cardia/noncardia) and histological subtype (diffuse/intestinal). Analytes were measured by high-performance liquid chromatography in prediagnostic plasma from 244 GC cases and 645 controls matched by age, gender, study centre and date of blood donation. Conditional logistic regression models adjusted by body mass index, total energy intake, smoking and Helicobacter pylori infection status were used to estimate relative cancer risks. After an average 3.2 years of follow-up, a negative association with GC risk was observed in the highest vs the lowest quartiles of plasma beta-cryptoxanthin (odds ratio (OR) = 0.53, 95% confidence intervals (CI) = 0.30-0.94, P(trend) = 0.006), zeaxanthin (OR = 0.39, 95% CI = 0.22-0.69, P(trend) = 0.005), retinol (OR = 0.55, 95% CI = 0.33-0.93, P(trend) = 0.005) and lipid-unadjusted alpha-tocopherol (OR = 0.59, 95% CI = 0.37-0.94, P(trend) = 0.022). For all analytes, no heterogeneity of risk estimates or significant associations were observed by anatomical subsite. In the diffuse histological subtype, an inverse association was observed with the highest vs lowest quartile of lipid-unadjusted alpha-tocopherol (OR = 0.26, 95% CI = 0.11-0.65, P(trend) = 0.003). These results show that higher plasma concentrations of some carotenoids, retinol and alpha-tocopherol are associated with reduced risk of GC.
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| 7. |
- Bamia, C, et al.
(författare)
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Dietary patterns among older Europeans: the EPIC-Elderly study
- 2005
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Ingår i: British Journal of Nutrition. - 1475-2662 .- 0007-1145. ; 94:1, s. 100-113
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Tidskriftsartikel (refereegranskat)abstract
- Overall dietary patterns have been associated with health and longevity. We used principal component (PC) and cluster analyses to identify the prevailing dietary patterns of 99 744 participants, aged 60 years or older, living in nine European countries and participating in the European Prospective Investigation into Cancer and Nutrition (EPIC-Elderly cohort) and to examine their socio-demographic and lifestyle correlates. Two PC were identified: PC1 reflects a 'vegetable-based' diet with an emphasis on foods of plant origin, rice, pasta and other grain rather than on margarine, potatoes and non-alcoholic beverages. PC2 indicates a 'sweet- and fat-dominated' diet with a preference for sweets, added fat and dairy products but not meat, alcohol, bread and eggs. PC1 was associated with a younger age, a higher level of education, physical activity, a higher BMI, a lower waist:hip ratio and never and past smoking. PC2 was associated with older age, less education, never having smoked, a lower BMI and waist:hip ratio and lower levels of physical activity. Elderly individuals in southern Europe scored positively on PC1 and about zero on PC2, whereas the elderly in northern Europe scored negatively on PC1 and variably on PC2. The results of cluster analysis were compatible with the indicated dietary patterns. 'Vegetable-based' and a 'sweet- and fat-dominated' diets are prevalent among the elderly across Europe, and there is a north-south gradient regarding their dietary choices. Our study contributes to the identification of groups of elderly who are likely to have different prospects for long-term disease occurrence and survival.
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| 8. |
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| 9. |
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| 10. |
- Lumbreras, B., et al.
(författare)
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Meat intake and bladder cancer in a prospective study: a role for heterocyclic aromatic amines?
- 2008
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Ingår i: Cancer Causes and Control. - : Springer Science and Business Media LLC. - 1573-7225 .- 0957-5243. ; 19:6, s. 649-656
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Tidskriftsartikel (refereegranskat)abstract
- Objective The suspect carcinogens, heterocyclic amines (HAAs), found in well-done meat require host-mediated metabolic activation before inducing DNA mutations. The role of SULT1A1 and of NAT2 on the activation of HAAs suggests that NAT2 rapid acetylator genotype and SULT1A1 allele variants can have an effect on HAA carcinogenicity. Methods Data were collected as part of a case-control study nested within the EPIC cohort, the Gen Air investigation. EPIC is a prospective study designed to investigate the relationship between nutrition and cancer. Information was collected through a non-dietary questionnaire on lifestyle variables and through a dietary questionnaire. The subjects were restricted to non-smokers. We calculated the matched odds ratio for bladder cancer risk using logistic regression, controlling for potential confounders. Results There were 227 bladder cases and 612 controls matched 1:3. Meat intake and NAT2 genotype were not independently associated with bladder cancer risk. A significant relationship was observed between bladder cancer risk and consumption of meat only among subjects with the rapid NAT2 genotype (odds ratios [OR] 2.9, 95% CI 1.0-7.9 for the 2nd quartile of meat intake; 3.6, 95% CI 1.3-9.7 for the 3rd quartile; and 3.5, 95% CI 1.2-9.7 for the 4th quartile), and was not present among subjects with the slow genotype. An interaction between NAT2 and meat intake was found in logistic regression (P = 0.034). No association was observed for SULT1A *1/2 genotype (1.0; 95% CI 0.7-1.5) and for SULT1A1 *2/2 genotype (0.9; 95% CI 0.5-1.7). Conclusions These results are suggestive of a role of meat intake and NAT2 on bladder cancer risk. They support the hypothesis that among subjects with the rapid NAT2 acetylation genotype higher levels of HAAs exposure are a bladder cancer risk factor. We did not observe an effect of SULT1A1 allele variants on this cancer. The present study adds new information on the possible long-term adverse effects of diets with high meat intake.
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| 11. |
- Newton-Cheh, Christopher, et al.
(författare)
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Genome-wide association study identifies eight loci associated with blood pressure
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:6, s. 666-676
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Tidskriftsartikel (refereegranskat)abstract
- Elevated blood pressure is a common, heritable cause of cardiovascular disease worldwide. To date, identification of common genetic variants influencing blood pressure has proven challenging. We tested 2.5 million genotyped and imputed SNPs for association with systolic and diastolic blood pressure in 34,433 subjects of European ancestry from the Global BPgen consortium and followed up findings with direct genotyping (N <= 71,225 European ancestry, N <= 12,889 Indian Asian ancestry) and in silico comparison (CHARGE consortium, N 29,136). We identified association between systolic or diastolic blood pressure and common variants in eight regions near the CYP17A1 (P = 7 x 10(-24)), CYP1A2 (P = 1 x 10(-23)), FGF5 (P = 1 x 10(-21)), SH2B3 (P = 3 x 10(-18)), MTHFR (P = 2 x 10(-13)), c10orf107 (P = 1 x 10(-9)), ZNF652 (P = 5 x 10(-9)) and PLCD3 (P = 1 x 10(-8)) genes. All variants associated with continuous blood pressure were associated with dichotomous hypertension. These associations between common variants and blood pressure and hypertension offer mechanistic insights into the regulation of blood pressure and may point to novel targets for interventions to prevent cardiovascular disease.
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| 12. |
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| 13. |
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| 14. |
- Alzari, Pedro M., et al.
(författare)
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Implementation of semi-automated cloning and prokaryotic expression screening : the impact of SPINE
- 2006
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Ingår i: Acta Crystallographica Section D. - 0907-4449 .- 1399-0047. ; 62, s. 1103-1113
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Tidskriftsartikel (refereegranskat)abstract
- The implementation of high- throughput ( HTP) cloning and expression screening in Escherichia coli by 14 laboratories in the Structural Proteomics In Europe ( SPINE) consortium is described. Cloning efficiencies of greater than 80% have been achieved for the three non- ligation- based cloning techniques used, namely Gateway, ligation- indendent cloning of PCR products ( LIC- PCR) and In- Fusion, with LIC- PCR emerging as the most cost- effective. On average, two constructs have been made for each of the approximately 1700 protein targets selected by SPINE for protein production. Overall, HTP expression screening in E. coli has yielded 32% soluble constructs, with at least one for 70% of the targets. In addition to the implementation of HTP cloning and expression screening, the development of two novel technologies is described, namely library- based screening for soluble constructs and parallel small- scale high- density fermentation.
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| 15. |
- Ballantyne, C., et al.
(författare)
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Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA(2) and cardiovascular diseases
- 2007
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Ingår i: European Journal of Cardiovascular Prevention & Rehabilitation. - 1741-8275. ; 14:1, s. 41344-41344
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Forskningsöversikt (refereegranskat)abstract
- Background A large number of observational epidemiological studies have reported generally positive associations' between circulating mass and activity levels of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA(2) markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors. Objectives By combination of data from individual participants from all relevant observational studies in a systematic,meta-analysis, with correction for regression dilution (using available data on serial measurements of Lp-PLA(2)), the Lp-PLA(2) Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA(2) with coronary heart disease (and, where data are sufficient with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA(2) and cardiovascular outcomes. Methods A central database is being established containing data on circulating Lp-PLA(2) values, sex and other potential confounding factors, age at baseline Lp-PLA(2) Measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA(2) will yield information on a total of about 15 000 cardiovascular disease endpoints.
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| 16. |
- Ballantyne, C., et al.
(författare)
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Collaborative meta-analysis of individual participant data from observational studies of Lp-PLA2 and cardiovascular diseases
- 2007
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Ingår i: European Journal of Cardiovascular Prevention & Rehabilitation. - : Oxford University Press (OUP). - 1741-8267 .- 1741-8275 .- 2047-4873. ; 14:1, s. 3-11
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Forskningsöversikt (refereegranskat)abstract
- BACKGROUND: A large number of observational epidemiological studies have reported generally positive associations between circulating mass and activity levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) and the risk of cardiovascular diseases. Few studies have been large enough to provide reliable estimates in different circumstances, such as in different subgroups (e.g., by age group, sex, or smoking status) or at different Lp-PLA2 levels. Moreover, most published studies have related disease risk only to baseline values of Lp-PLA2 markers (which can lead to substantial underestimation of any risk relationships because of within-person variability over time) and have used different approaches to adjustment for possible confounding factors. OBJECTIVES: By combination of data from individual participants from all relevant observational studies in a systematic 'meta-analysis', with correction for regression dilution (using available data on serial measurements of Lp-PLA2), the Lp-PLA2 Studies Collaboration will aim to characterize more precisely than has previously been possible the strength and shape of the age and sex-specific associations of plasma Lp-PLA2 with coronary heart disease (and, where data are sufficient, with other vascular diseases, such as ischaemic stroke). It will also help to determine to what extent such associations are independent of possible confounding factors and to explore potential sources of heterogeneity among studies, such as those related to assay methods and study design. It is anticipated that the present collaboration will serve as a framework to investigate related questions on Lp-PLA2 and cardiovascular outcomes. METHODS: A central database is being established containing data on circulating Lp-PLA2 values, sex and other potential confounding factors, age at baseline Lp-PLA2 measurement, age at event or at last follow-up, major vascular morbidity and cause-specific mortality. Information about any repeat measurements of Lp-PLA2 and potential confounding factors has been sought to allow adjustment for possible confounding and correction for regression dilution. The analyses will involve age-specific regression models. Synthesis of the available observational studies of Lp-PLA2 will yield information on a total of about 15 000 cardiovascular disease endpoints.
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| 17. |
- 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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| 18. |
- Berglund, Anders, et al.
(författare)
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E-readiness of University Divisions in Online Education
- 2006
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Ingår i: Netlearning 06', Ronneby.
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Konferensbidrag (refereegranskat)abstract
- E-readiness can be defined as the degree to which a community is prepared to participate in the networked world. In this paper the concept of e-readiness is used in terms of how internal and external factors affect the delivery of online education offered by universities. The paper applies the macro level five forces model as adopted by Chan and Welebir (2003) in the context of micro (university divisional level). Thus, the purpose is not to have generalizable findings, but rather use the delivery of online education as determinant for the level of universities' e-readiness, and explore the factors affecting e-readiness and ways of utilizing the factors as central to the study. Using a qualitative method case study interviews on divisional level were used to obtain in-depth empirical evidence. The study appears to indicate potential need to further modify the five forces model by Chan and Welebir (2003) due to the non-commercial natureof the Swedish education system. Also, co-operation in providing educational services such as the Net University in Sweden precludes market forces determination by universities internally. No specialized training program for the instructors to fit any special needs of students particular to online education was perceived.
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| 19. |
- Berglund, Birgitta, et al.
(författare)
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Measurement of Perception : A European Network "Measuring the Impossible"
- 2009
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Ingår i: Proceedings of the 14th International Congress of Metrology. - Paris, France : Bureau international des poids et mesures, BIPM. ; , s. 1-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The European 'Measuring the Impossible' Network MINET promotes new research activities in measurement dependent on human perception and/or interpretation. This includes the perceived attributes of products and services, such as quality or desirability, and societal parameters such as security and well-being. The main achievements so far include on-line consortium databases, research repository; workshops, think tanks, study visits; training course and book. The MINET consortium aims at consensus about how 'generic' metrological issues: Measurement concepts & terminology, Measurement techniques, Measurement uncertainty, Decision-making & impact assessment, can be applied specifically to the 'Measurement of Persons' in terms of 'Man as a Measurement Instrument' and 'Measuring Man'.
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| 20. |
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| 21. |
- Berglund, Jonas, et al.
(författare)
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Hotspots of biased nucleotide substitutions in human genes
- 2009
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Ingår i: PLoS biology. - : Public Library of Science (PLoS). - 1544-9173 .- 1545-7885. ; 7:1, s. e26-
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Tidskriftsartikel (refereegranskat)abstract
- Genes that have experienced accelerated evolutionary rates on the human lineage during recent evolution are candidates for involvement in human-specific adaptations. To determine the forces that cause increased evolutionary rates in certain genes, we analyzed alignments of 10,238 human genes to their orthologues in chimpanzee and macaque. Using a likelihood ratio test, we identified protein-coding sequences with an accelerated rate of base substitutions along the human lineage. Exons evolving at a fast rate in humans have a significant tendency to contain clusters of AT-to-GC (weak-to-strong) biased substitutions. This pattern is also observed in noncoding sequence flanking rapidly evolving exons. Accelerated exons occur in regions with elevated male recombination rates and exhibit an excess of nonsynonymous substitutions relative to the genomic average. We next analyzed genes with significantly elevated ratios of nonsynonymous to synonymous rates of base substitution (dN/dS) along the human lineage, and those with an excess of amino acid replacement substitutions relative to human polymorphism. These genes also show evidence of clusters of weak-to-strong biased substitutions. These findings indicate that a recombination-associated process, such as biased gene conversion (BGC), is driving fixation of GC alleles in the human genome. This process can lead to accelerated evolution in coding sequences and excess amino acid replacement substitutions, thereby generating significant results for tests of positive selection.
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| 22. |
- Berglund, T., et al.
(författare)
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High velocity compaction of high speed steel powder : possibilities and constraints
- 2007
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Ingår i: Proceedings of the Euro Powder Metallurgy Congress and Exhibition, Euro PM 2007. ; , s. 21-26
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Konferensbidrag (refereegranskat)abstract
- It is known that gas atomized powders as well as high alloyed metal powders are difficult to press into green bodies using conventional quasi static pressing techniques. However, the development of the high velocity compaction (HVC) technique has expanded the possibility to compact a larger spectrum of metal powders. Although the HVC technique has many similarities with conventional pressing techniques, the high energy impact makes it an interesting technique not only for the pressing of conventional metal powders to green bodies of high density but also for the pressing of "difficult to press metal powders". Today, high speed steel (HSS) is increasingly being used in different types of components. Consequently, there is an increasing interest in the near net shape manufacturing of HSS components. The aim of the present study is to evaluate the possibility to utilize HVC to press green bodies from different types of HSS powder covering both gas and water atomized HSS powders. The results show that the HSS powders investigated differ with respect to compaction properties, i.e. compressibility and green body quality. While the water atomized powders exhibit very good compaction properties, resulting in green bodies of high density, good surface finish and high strength, the gas atomized powders cannot be pressed in the as-atomized condition using HVC. However, agglomerated as well as milled gas atomized HSS powders show significant improved compaction properties compared to the as-atomized powders, although all showed defects of varying sizes depending on the applied energy during compaction.
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| 23. |
- Botteldooren, D, et al.
(författare)
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Experimental investigation of noise annoyance caused by high-speed trains.
- 2005
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Ingår i: ICSV 2005–Twelfth International Congress on Sound and Vibration. - : IIAV/CAPS-IST, Lissabon.
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Bokkapitel (refereegranskat)abstract
- The difference in perceived noise annoyance caused by train and highway noise at the same averaged noise level, has led to the introduction of the ’railway bonus’. This bonus has found its way to the noise legislation in many countries, leading to more relaxed restrictions on time averaged noise levels, LAeq. With the introduction of high-speed trains and train-like transportation systems based on magnetic levitation, the question has risen whether the railway bonus can still be applied. The paper reports on an experiment that was conducted to answer this question. The experiment that was performed was different from previous efforts in many ways. Most importantly, the experiment was conducted in a realistic setting, a holiday cottage, and participants were asked to engage in light daily activities such as reading a magazine during the tests. Traffic noise was reproduced in an ecologically valid way, using outdoor loudspeakers. Every ten minutes the participants were asked to judge noise annoyance. At the beginning of the experiment and after about 1.5 hours the participants were also asked to rate a set of 7 master scaling sounds. After this experiment, a more conventional listening test was conducted using 45-s excerpts. The experiment was also unique in the way that 100 participants were selected to be representative for the Dutch population. The selection procedure involved careful screening based on a survey that was administered at the doorstep of 1500 persons’ homes.
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| 24. |
- Botteldooren, D, et al.
(författare)
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Perceived Noise Annoyance Caused by Maglev Trains. Management Summary.
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The annoyance impact in realistic settings of traffic noise was assessed for one, two or four train passages, primarily high-speed trains, or continuous road traffic noise. An innovative system for selecting representative participants from the Dutch population was implemented, as regards a number of critical variables (age, gender, level of education, noise sensitivity, reported anxiety, home exposure to train and road traffic noise, general quality of living environment, and general health). In total, 1500 candidate participants responded to the specifically constructed questionnaire with items from a nation-wide Dutch survey and the Eurobarometer. Participants with typical Dutch response profile were recruited on a first come, first serve basis (in total 80 plus 21 extra persons. In the experiment, 5-7 participants were seated to be relaxed and to be reading a magazine or newspaper. The were served refreshments. Traffic noise was reproduced in outdoor loudspeakers in an ecologically valid way. Every 10 min, participants were asked to assess noise annoyance. At the beginning and at brief intervals during the experiment, participants assessed the annoyance of a set of 7 reference sounds utilized for master scaling. At the same average façade exposure, no significant annoyance difference was neither found for Maglev and TGV, nor for conventional trains and the high-speed trains (only tested up to 65 dBA). The latter result contradicts Vos et al.’s earlier findings. Neugebauer at al.’s results fall within the spread in annoyance values due to distance to the track and vehicle speed that we observed. Field surveys have shown that for the same average sound level, railway noise evokes less annoyance than dense road traffic noise, at least for a certain interval of levels. Although our experiment included several of the factors that may contribute to this effect, we were unable to observe this kind of effect, except for the case when the sounds were recorded at a distance of more than 100 m.
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| 25. |
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