Ahrens, Wolfgang
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Ahrens, Wolfgang
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Ahrens, Wolfgang
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Item-typ:Veröffentlichung, Epidemiologische Untersuchungen zur Assoziation von Hodenkrebs und elektromagnetischen Feldern(2002-11-26); ; ; In a population-based case-control-study we examined the association of testicular cancer and exposure to electromagnetic fields (EMF). The multicenter-study included 269 cases, newly diagnosed between 1995 and 1997, and 797 controls, randomly selected from mandatory registries of residents. Odds Ratios (OR) and 95% Confidence Intervals (CI) were calculated, stratified by age and region, and weighted by intensity, duration and distance using conditional logistic regression. Additionally, in Hamburg residential exposure to high voltage power-lines was analyzed. The analysis included 145 cases and 313 controls. The simplest exposure model took into account whether cases and controls had ever lived within the distance of 250 meters near a high voltage power-line. ORs and 95%CI were calculated using unconditional logistic regression. According to self-reports the OR for jobs near radar units is 1.0 (95%CI=0.60;1.75), near electrical machines 1.0 (95%CI=0.72;1.33), radiofrequency radiation devices 0.9 (95%CI=0.60;1.24), high voltage power-lines 0.7 (95%CI=0.38;1.18), and visual display units 0.9 (95%CI=0.67;1.21). Weighting the exposure leads only to marginal changes in the risk estimates. The OR for residential exposure to high voltage power-lines in Hamburg is 1.5 (95%CI=0.89;2.43). In all, EMF exposure does not seem to be a relevant risk factor for testicular cancer in our study.Dissertation346 239 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Placing sensory science in health Research : Correlates of sensory taste perception&preferences, healthy eating and health outcomes in European Children(2019-04-29); ; ; Based on unique data from a large-scale pan-European cohort study in children, adolescents and their families, the present thesis investigated for the first time factors that may influence sensory taste perception and taste preferences in childhood. This thesis took advantage of the great diversity of food environments across Europe and considered biological/ physiological factors (sex, age, number of fungiform papillae) as well as genetic and familial factors (biological parents, parental consumer attitudes/ education level and dietary habits) simultaneously. Since it is very challenging to obtain valid results about sensory taste perception from children, instruments and test systems were adapted to be used in children with various cultural backgrounds. This thesis analysed sensory test methods to investigate their feasibility and suitability for future large-scale observational studies in young populations. Connecting sensory taste perception with health outcomes presents an innovative research field.Dissertation474 936 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Qualitätsmanagement bei der Nutzung biologischer Proben im Rahmen der epidemiologischen Multizentrenstudie IDEFICS(2016-04-27); ; ; This PhD thesis tackles the use of biological samples in epidemiology. A quality managment system was implemented in the context of the paediatric IDEFICS study and evaluated consecutively. Data gained from analysis of biological samples were used for the generation of reference percentiles and epidemiological risk assessment.Dissertation370 517 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, ASSOZIATIONEN ZWISCHEN PFLANZLICHEN PRÄPARATEN ZUR LINDERUNG KLIMAKTERISCHER BESCHWERDEN UND DEM POSTMENOPAUSALEN BRUSTKREBSRISIKO :Datenanalyse einer populationsbezogenen Fall-Kontroll-Studie(2009-04-29); ; ; The use of herbal preparations (HEP) to alleviate menopausal disorders tends to increase, since women seek for alternatives to menopausal hormone therapy (HT). Whether phytoestrogens and other polyphenolic substances in HEP exert a beneficial, any effect or increase the risk for breast cancer is of ongoing debate, and data on HEP use is sparse. Within a large German case-control-study, associations between patterns of use of HEP and incident breast cancer were investigated in 10121 postmenopausal women (3464 cases, 6657 controls). Information on HEP use was collected in face-to-face interviews supported by a list of brand names. Logistic and polytomous regression analysis were performed, adjusted for HT and lifestyle factors. Ever use of any HEP (9.9%) was inversely associated with invasive breast cancer (OR 0.74, 95%CI 0.62-0.87) as well as current and past use (OR 0.70, 95%CI 0.53-0.91; OR 0.75, 95%CI 0.61-0.91, respectively). Increasing duration (years) of HEP was related to risk for invasive tumours in a dose-dependant manner (0.94, 95%CI 0.93-0.98, p = 0.03). Considering histology, risk reduction of use of HEP was similar for invasive ductal (OR 0.72, 95%CI 0.60-0.87) and for combined lobular/mixed/tubular (OR 0.76, 95%CI 0.58-1.01) but not for in situ tumours (1.34, 95%CI 0.86-2.09). Regarding ER/PR status, use of HEP appeared to be slightly stronger associated with negative compared to positive status (ER/PR both neg. OR 0.66, 95%CI 0.47-0.93; ER or/and PR pos. OR 0.74, 95%CI 0.62-0.89). These results support the hypothesis, that HEP may be protective against invasive breast cancer. Among several conceivable modes of action, those independent from estrogen receptor mediated pathways seem to be involved (i.e. anti-oxidation and apoptosis).Dissertation256 426 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Taste preferences, diet and overweight in European children: An epidemiological perspective(2012-09-07); ; ; This thesis investigated taste preferences of children from eight European countries. It is based on data from the epidemiological IDEFICS study. The methodological part of the thesis revealed that the reproducibility of the IDEFICS taste preference and -sensitivity tests was high while the reproducibility of the IDEFICS food frequency questionnaire (CEHQ-FFQ) was comparable to that of previous FFQs. Etiological analyses showed that country affiliation was the strongest predictor of taste preferences followed by age. Between ages 6 and 9, sweet and salty preference increased while umami preference decreased. Other factors were not uniformly related to taste preferences. Taste preferences for fat and sweet were also associated with an increased probability of overweight. However, they were not associated with the consumption of sweet and fatty foods. Taste preferences for fat or sweet taste could also not explain the association between TV habits and detrimental dietary behavior.Dissertation387 134 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Bone Stiffness and its Association with Physical Activity in Children : an Epidemiological Perspective(2015-04-23); ; ; Monitoring and promotion of skeletal development by physical activity (PA) in early life may optimize bone strength during growth in order to delay age-related bone loss and prevent osteoporotic fractures. In contrast to commonly applied x-ray methods, the assessment of calcaneal bone stiffness (SI) by quantitative ultrasound (QUS) may be an alternative method to examine bone health in children over several years, without using ionized radiation. This thesis aims to enhance knowledge on the age-specific distribution of SI, and to investigate the role of PA on SI in 2-10-year-old European children from the IDEFICS study (Identification and prevention of dietary- and lifestyle- induced health effects in children and infants). The aims of this cumulative thesis were investigated and discussed in one narrative review and three original peer-reviewed publications. Based on more than 10,000 children, this thesis provides the derivation of the first age-, sex- and height-specific reference values of SI, which point to a decline in SI until the age of 5-6 years, while an increase in SI has been observed from the age of 6 years onwards. Cross-sectional and case-control analyses of the IDEFICS data indicate a positive association between PA and SI in children and support the beneficial osteogenic effect of vigorous and weight-bearing PA as observed in previous studies, which examined bone health with x-ray methods. These comparable results as well as the developed reference data, which form the basis for comparing bone health of children with a healthy reference population, support the use of QUS in further epidemiological studies and clinical settings for monitoring bone health for instance during interventions.Dissertation401 441 - Some of the metrics are blocked by yourconsent settings
Item-typ:Veröffentlichung, Sleep duration and its role in the aetiology of cardio-metabolic health outcomes(2011-11-16); ; ; An adequate amount of sleep is believed to be important for optimal health and functioning throughout life and changes in sleep duration were found to be associated with several especially cardio-metabolic - health outcomes in adults as well as in children. The factors that influence sleep duration are multi-factorial and the interplay between sleep duration and other factors in the aetiology of cardio-metabolic outcomes is complex and not fully understood yet. Internationally comparable data from children aged 2 to 9 years participating in the IDEFICS study has been analysed to investigate on differences in and determinants of sleep duration as well as on the association between sleep duration and overweight in children. Systematic reviews give an insight in the literature on the longitudinal relationship between sleep duration and weight status in children and adults on the one hand, and on the epidemiological evidence regarding sleep duration and cardiovascular mortality on the other hand. A meta-analysis has been conducted to quantify the dose dependency of the association between sleep duration and cardiovascular mortality. Nocturnal sleep duration differed significantly (P < 0.001) by up to 1.7 hours between countries in univariate as well as in multivariate analysis. Disparities between Northern, Southern and Eastern Europe were striking, with children from Northern countries sleeping the longest. The factor that was found to mainly affect children s sleep duration was country affiliation. Age also had a significant effect in all models, but accounted for less change in sleep duration than country. No association was found with behavioral aspects or environmental factors, such as season or daylight. A negative association of sleep duration with a higher probability of being overweight was revealed. This relationship was attenuated by an adjustment for geographic region, whereas no effect modification by region was found. Generally the association appeared to be much stronger in school children than in preschool children. The relationship between sleep duration and weight status can not only be seen in children but also in adults even if the results are less consistent with increasing age. The meta-analysis showed a clear dose-effect relationship of sleep duration on cardiovascular mortality. For stroke and cardiovascular diseases in general (CVD) the association could mainly be seen with sleep durations of more than 7.5 hours and the direction of the relationship seemed to be similar in men and in women. For coronary heart disease (CHD)the effects of sleep duration were generally stronger, but differed between sexes, with short sleep duration being associated with CHD to a higher extent in men than in women. In contrast, long sleep duration seemed to increase the risk in women, while no significant effect was seen in men. In conclusion we suggested a twofold effect of sleep duration on cardiovascular outcomes: directly and indirectly via the effect of overweight. Furthermore, investigation on sleep duration as a tracking risk factor for cardio-metabolic outcomes as well as internationally comparable studies to give insight in regional aspects of sleep duration was proposed. Such research might create the basis for specific and appropriate public health actions with regard to sleep induced cardio-metabolic conditions.Dissertation303 473