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| 24. |
- Björk, Jonas, et al.
(författare)
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An efficient sampling strategy for selection of biobank samples using risk scores
- 2017
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 45:17_suppl, s. 41-44
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The aim of this study was to suggest a new sample-selection strategy based on risk scores in case-control studies with biobank data. Methods: An ongoing Swedish case-control study on fetal exposure to endocrine disruptors and overweight in early childhood was used as the empirical example. Cases were defined as children with a body mass index (BMI) ≥18 kg/m2 (n=545) at four years of age, and controls as children with a BMI of 1/217 kg/m2 (n=4472 available). The risk of being overweight was modelled using logistic regression based on available covariates from the health examination and prior to selecting samples from the biobank. A risk score was estimated for each child and categorised as low (0-5%), medium (6-13%) or high (≥14%) risk of being overweight. Results: The final risk-score model, with smoking during pregnancy (p=0.001), birth weight (p<0.001), BMI of both parents (p<0.001 for both), type of residence (p=0.04) and economic situation (p=0.12), yielded an area under the receiver operating characteristic curve of 67% (n=3945 with complete data). The case group (n=416) had the following risk-score profile: low (12%), medium (46%) and high risk (43%). Twice as many controls were selected from each risk group, with further matching on sex. Computer simulations showed that the proposed selection strategy with stratification on risk scores yielded consistent improvements in statistical precision. Conclusions: Using risk scores based on available survey or register data as a basis for sample selection may improve possibilities to study heterogeneity of exposure effects in biobank-based studies.
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- Bonde, Jens Peter, et al.
(författare)
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Fertility and markers of male reproductive function in Inuit and European populations spanning large contrasts in blood levels of persistent organochlorines
- 2008
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Ingår i: Environmental Health Perspectives. - : Environmental Health Perspectives. - 1552-9924 .- 0091-6765. ; 116:3, s. 269-277
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Forskningsöversikt (refereegranskat)abstract
- OBJECTIVE: We synthesized the main findings from an international epidemiologic study on the impact of biopersistent organic pollutants (POPs) on human reproductive function. DATA SOURCES AND EXTRACTION: We used a database with interview and biological data from 2,269 women and their spouses, and 18 published core papers. DATA SYNTHESIS: The study did not provide direct evidence of hormone-like activity of the polychlorinated biphenyl (PCB) congener CB-153 and the main dichlorodiphenyltrichloroethane (DDT) metabolite, 1 1 1 -dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p'-DDE), as serum concentrations of these compounds were not consistently related to either endogenous or exogenous hormone activity in serum. Nevertheless several links bewteen POP exposure and biomarkers of male reproductive function were identified. First, an association between high CB-153 serum levels and low sperm counts was detected within a subgroup of men with short androgen receptor CAG repeat length. Second, a relationship between increased CB-153 serum concentrations and decreased sperm motility was seen in all four studied regions, and indications of reduced neutral alpha-glucosidase activity in seminal plasma point to a post-testicular effect. Third, damage of sperm chromatin integrity was considerably less frequent in Greenlandic Inuits compared with that in European groups, and only in the latter was impairment of sperm chromatin integrity related to POPs. Despite these effects, fertility in terms of time taken to conceive was not related to POPs except in Inuits. A likely explanation of the latter was not identified. CONCLUSIONS: POPs may interfere with male reproductive function without major impact on fertility. The data do not provide direct evidence for endocrine disruption, hence other mechanisms should also be considered.
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| 27. |
- Giwercman, Aleksander, et al.
(författare)
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Androgen receptor gene CAG repeat length as a modifier of the association between persistent organohalogen pollutant exposure markers and semen characteristics
- 2007
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Ingår i: Pharmacogenetics & Genomics. - : Ovid Technologies (Wolters Kluwer Health). - 1744-6872. ; 17:6, s. 391-401
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Tidskriftsartikel (refereegranskat)abstract
- Objectives Exposure to persistent organohalogen pollutants was suggested to impair male reproductive function. A gene-environment interaction has been proposed. No genes modifying the effect of persistent organohalogen pollutants on reproductive organs have yet been identified. We aimed to investigate whether the CAG and GGN polymorphisms in the androgen receptor gene modify the effect of persistent organohalogen pollutant exposure on human sperm characteristics. Methods Semen and blood from 680 men [mean (SD) age 34 (10) years] from Greenland, Sweden, Warsaw (Poland) and Kharkiv (Ukraine) were collected. Persistent organohalogen pollutant exposure was assessed by measuring serum levels of 2,2,4,4,5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE). Semen characteristics (volume, sperm concentration, total count proportion of progressively motile and morphology) and DNA fragmentation index (DFI) were determined. CAG and GGN repeat lengths were determined by direct sequencing of leukocyte DNA. Results A statistically significant interaction was found between the CB-153 group and CAG repeat category in relation to sperm concentration and total sperm count (P=0.03 and 0.01, respectively). For p,p'-DDE, in the European cohorts a significant interaction was found in relation to DFI (P=0.01). For CAG<20, sperm concentration and total sperm count were 35 and 42% lower, respectively, when the group with CB-153 exposure above median was compared with that below the median. DF1 was 40% higher in the high p,p'-DDE exposure group for CAG < 21. Conclusions This study indicated that the androgen receptor CAG repeat length might modify the susceptibility of an individual to the adverse effects of persistent organohalogen pollutant exposure on semen quality. Other studies regarding this matter are warranted.
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| 30. |
- Holmberg, Sara, et al.
(författare)
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High levels of vitamin D associated with less ischemic heart disease - a nested case-control study among rural men in Sweden
- 2017
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Ingår i: AAEM. - : Institute of Rural Health. - 1232-1966 .- 1898-2263. ; 24:2, s. 288-293
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Tidskriftsartikel (refereegranskat)abstract
- Introduction and objective. Low levels of serum vitamin D have been associated with increased occurrence of ischemic heart disease (IHD), but findings are inconsistent, e.g. seasonal variation is not always considered in the analyses. The aim of this study was to investigate whether vitamin D is associated with IHD among rural middle-aged men in Sweden when seasonal variation is taken into account. Materials and method. A nested case-control study was performed within a population-based cohort of Swedish farmers and rural residents followed for 20 years. Outcomes were from national health registers. For 276 cases (IHD at any time during follow-up), and for 276 aged-matched controls free of cardiovascular diseases or diabetes, serum levels of vitamin D (25-hydroxyvitamin D-3) were analyzed with liquid chromatography/tandem mass spectrometry (LC/MS/MS), in stored blood samples drawn at the baseline survey in 1990-91. The odds ratio (OR) with 95% confidence intervals (CI) of IHD for vitamin D-quartiles (based on measured as well as adjusted for month of sampling) was evaluated in logistic regression models; potential confounders were taken into account. Results. The measured mean vitamin D levels were 27.6 ng/ml(standard deviation (sd) 8.2 ng/ml) and 28.8 ng/ml (sd 9.0) among cases and controls, respectively. Compared to the quartile with the lowest month-adjusted vitamin D levels, the risk of IHD was significantly lower in the highest quartile (OR=0.46, 95% CI 0.25-0.84, p=0.012) in the fully-adjusted model. Conclusion. Rural Swedish men in the highest quartile of serum vitamin D had halved relative risk of IHD, compared to those in the lowest quartile.
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