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1.  Change in paternal grandmothers´ early food supply influenced cardiovascular mortality of the female grandchildren 
BMC Genetics  2014;15:12.
Background
This study investigated whether large fluctuations in food availability during grandparents' early development influenced grandchildren's cardiovascular mortality. We reported earlier that changes in availability of food - from good to poor or from poor to good - during intrauterine development was followed by a double risk of sudden death as an adult, and that mortality rate can be associated with ancestors´ childhood availability of food. We have now studied transgenerational responses (TGR) to sharp differences of harvest between two consecutive years´ for ancestors of 317 people in Överkalix, Sweden.
Results
The confidence intervals were very wide but we found a striking TGR. There was no response in cardiovascular mortality in the grandchild from sharp changes of early exposure, experienced by three of the four grandparents (maternal grandparents and paternal grandfathers). If, however, the paternal grandmother up to puberty lived through a sharp change in food supply from one year to next, her sons´ daughters had an excess risk for cardiovascular mortality (HR 2.69, 95% confidence interval 1.05-6.92). Selection or learning and imitation are unlikely explanations. X-linked epigenetic inheritance via spermatozoa seemed to be plausible, with the transmission, limited to being through the father, possibly explained by the sex differences in meiosis.
Conclusion
The shock of change in food availability seems to give specific transgenerational responses.
doi:10.1186/1471-2156-15-12
PMCID: PMC3929550  PMID: 24552514
Epidemiology; Food change; Environmental shock; Human transgenerational response; Cardiovascular mortality; Överkalix
2.  Muscular strength and adiposity as predictors of adulthood cancer mortality in men 
BACKGROUND
We examined the associations between muscular strength, markers of overall and central adiposity and cancer mortality in men.
METHODS
Prospective cohort study including 8,677 men aged 20-82 years followed from 1980 to 2003. Participants were enrolled in The Aerobics Centre Longitudinal Study, the Cooper Clinic in Dallas, Texas, U.S. Muscular strength was quantified by combining 1-repetition maximal measures for leg and bench presses. Adiposity was assessed by body mass index (BMI), percent body fat, and waist circumference.
RESULTS
Cancer death rates per 10,000 person-years adjusted for age and examination year were: 17.5, 11.0, and 10.3 across incremental thirds of muscular strength (P=0.001); 10.9, 13.4, and 20.1 across BMI groups of 18.5-24.9, 25.0-29.9, and ≥30kg/m2, respectively (P=0.008); 11.6 and 17.5 for normal (<25%) and high percent body fat (≥25%), respectively (P=0.006); and 12.2 and 16.7 for normal (≤102 cm) and high waist circumference (>102 cm), respectively (P=0.06). After adjusting for additional potential confounders, hazard ratios (95% confidence intervals) were 1.00 (referent), 0.65 (0.47-0.90), and 0.61 (0.44-0.85) across incremental thirds of muscular strength, respectively (P=0.003 for linear trend). Further adjustment for BMI, percent body fat, waist circumference, or cardiorespiratory fitness had little effect on the association. The associations of BMI, percent body fat, or waist circumference with cancer mortality did not persist after further adjusting for muscular strength (all P≥0.1).
CONCLUSIONS
Higher levels of muscular strength are associated with lower cancer mortality risk in men, independent of clinically established measures of overall and central adiposity, and other potential confounders.
doi:10.1158/1055-9965.EPI-08-1075
PMCID: PMC3762582  PMID: 19366909
Muscular strength; obesity; cancer; cardiorespiratory fitness; resistance exercise
3.  Association of objectively measured physical activity with body components in European adolescents 
BMC Public Health  2013;13:667.
Background
Physical activity (PA) is suggested to contribute to fat loss not only through increasing energy expenditure “per se” but also increasing muscle mass; therefore, it would be interesting to better understand the specific associations of PA with the different body’s components such as fat mass and muscle mass. The aim of the present study was to examine the association between objectively measured PA and indices of fat mass and muscle components independently of each other giving, at the same time, gender-specific information in a wide cohort of European adolescents.
Methods
A cross-sectional study in a school setting was conducted in 2200 (1016 males) adolescents (14.7 ±1.2 years). Weight, height, skinfold thickness, bioimpedance and PA (accelerometry) were measured. Indices of fat mass (body mass index, % fat mass, sum of skinfolds) and muscular component (assessed as fat-free mass) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat-free mass and fat mass when possible.
Results
Vigorous PA was positively associated with height (p < 0.05) in males, whilst, vigorous PA, moderate-vigorous PA and average PA were negatively associated with all the indices of fat mass (all p < 0.01) in both genders, except for average PA in relation with body mass index in females. Regarding muscular components, vigorous PA showed positive associations with fat-free mass and muscle mass (all p < 0.05) in both genders. Average PA was positively associated with fat-free mass (both p < 0.05) in males and females.
Conclusion
The present study suggests that PA, especially vigorous PA, is negatively associated with indices of fat mass and positively associated with markers of muscle mass, after adjusting for several confounders (including indices of fat mass and muscle mass when possible). Future studies should focus not only on the classical relationship between PA and fat mass, but also on PA and muscular components, analyzing the independent role of both with the different PA intensities.
doi:10.1186/1471-2458-13-667
PMCID: PMC3723445  PMID: 23866681
Physical activity; Fat mass; Muscular components; Adolescence
5.  Perceived neighborhood environment and physical activity in 11 countries: Do associations differ by country? 
Background
Increasing empirical evidence supports associations between neighborhood environments and physical activity. However, since most studies were conducted in a single country, particularly western countries, the generalizability of associations in an international setting is not well understood. The current study examined whether associations between perceived attributes of neighborhood environments and physical activity differed by country.
Methods
Population representative samples from 11 countries on five continents were surveyed using comparable methodologies and measurement instruments. Neighborhood environment × country interactions were tested in logistic regression models with meeting physical activity recommendations as the outcome, adjusted for demographic characteristics. Country-specific associations were reported.
Results
Significant neighborhood environment attribute × country interactions implied some differences across countries in the association of each neighborhood attribute with meeting physical activity recommendations. Across the 11 countries, land-use mix and sidewalks had the most consistent associations with physical activity. Access to public transit, bicycle facilities, and low-cost recreation facilities had some associations with physical activity, but with less consistency across countries. There was little evidence supporting the associations of residential density and crime-related safety with physical activity in most countries.
Conclusion
There is evidence of generalizability for the associations of land use mix, and presence of sidewalks with physical activity. Associations of other neighborhood characteristics with physical activity tended to differ by country. Future studies should include objective measures of neighborhood environments, compare psychometric properties of reports across countries, and use better specified models to further understand the similarities and differences in associations across countries.
doi:10.1186/1479-5868-10-57
PMCID: PMC3663693  PMID: 23672435
Physical activity; Built environment; Neighborhood environment; International; Generalizability; Moderator
6.  Objectively Measured Physical Activity and Sedentary Time during Childhood, Adolescence and Young Adulthood: A Cohort Study 
PLoS ONE  2013;8(4):e60871.
Background
To know how moderate-to-vigorous physical activity (MVPA) and sedentary time change across lifespan periods is needed for designing successful lifestyle interventions. We aimed to study changes in objectively measured (accelerometry) MVPA and sedentary time from childhood to adolescence and from adolescence to young adulthood.
Methods
Estonian and Swedish participants from the European Youth Heart Study aged 9 and 15 years at baseline (N = 2312) were asked to participate in a second examination 6 (Sweden) to 9/10 (Estonia) years later. 1800 participants with valid accelerometer data were analyzed.
Results
MVPA decreased from childhood to adolescence (−1 to −2.5 min/d per year of follow-up, P = 0.01 and <0.001, for girls and boys respectively) and also from adolescence to young adulthood (−0.8 to −2.2 min/d per year, P = 0.02 and <0.001 for girls and boys, respectively). Sedentary time increased from childhood to adolescence (+15 and +20 min/d per year, for girls and boys respectively, P<0.001), with no substantial change from adolescence to young adulthood. Changes in both MVPA and sedentary time were greater in Swedish than in Estonian participants and in boys than in girls. The magnitude of the change observed in sedentary time was 3–6 time larger than the change observed in MVPA.
Conclusions
The decline in MVPA (overall change = 30 min/d) and increase sedentary time (overall change = 2∶45 h/d) observed from childhood to adolescence are of concern and might increase the risk of developing obesity and other chronic diseases later in life. These findings substantially contribute to understand how key health-related behaviors (physical activity and sedentary) change across important periods of life.
doi:10.1371/journal.pone.0060871
PMCID: PMC3634054  PMID: 23637772
7.  Patterns of neighborhood environment attributes related to physical activity across 11 countries: a latent class analysis 
Background
Neighborhood environment studies of physical activity (PA) have been mainly single-country focused. The International Prevalence Study (IPS) presented a rare opportunity to examine neighborhood features across countries. The purpose of this analysis was to: 1) detect international neighborhood typologies based on participants’ response patterns to an environment survey and 2) to estimate associations between neighborhood environment patterns and PA.
Methods
A Latent Class Analysis (LCA) was conducted on pooled IPS adults (N=11,541) aged 18 to 64 years old (mean=37.5 ±12.8 yrs; 55.6% women) from 11 countries including Belgium, Brazil, Canada, Colombia, Hong Kong, Japan, Lithuania, New Zealand, Norway, Sweden, and the U.S. This subset used the Physical Activity Neighborhood Environment Survey (PANES) that briefly assessed 7 attributes within 10–15 minutes walk of participants’ residences, including residential density, access to shops/services, recreational facilities, public transit facilities, presence of sidewalks and bike paths, and personal safety. LCA derived meaningful subgroups from participants’ response patterns to PANES items, and participants were assigned to neighborhood types. The validated short-form International Physical Activity Questionnaire (IPAQ) measured likelihood of meeting the 150 minutes/week PA guideline. To validate derived classes, meeting the guideline either by walking or total PA was regressed on neighborhood types using a weighted generalized linear regression model, adjusting for gender, age and country.
Results
A 5-subgroup solution fitted the dataset and was interpretable. Neighborhood types were labeled, “Overall Activity Supportive (52% of sample)”, “High Walkable and Unsafe with Few Recreation Facilities (16%)”, “Safe with Active Transport Facilities (12%)”, “Transit and Shops Dense with Few Amenities (15%)”, and “Safe but Activity Unsupportive (5%)”. Country representation differed by type (e.g., U.S. disproportionally represented “Safe but Activity Unsupportive”). Compared to the Safe but Activity Unsupportive, two types showed greater odds of meeting PA guideline for walking outcome (High Walkable and Unsafe with Few Recreation Facilities, OR= 2.26 (95% CI 1.18-4.31); Overall Activity Supportive, OR= 1.90 (95% CI 1.13-3.21). Significant but smaller odds ratios were also found for total PA.
Conclusions
Meaningful neighborhood patterns generalized across countries and explained practical differences in PA. These observational results support WHO/UN recommendations for programs and policies targeted to improve features of the neighborhood environment for PA.
doi:10.1186/1479-5868-10-34
PMCID: PMC3615945  PMID: 23497187
Built environment; International; Recreation; Surveillance; Exercise
8.  Cutaneous Microdialysis: Cytokine Evidence for Altered Innate Reactivity in the Skin of Psoriasis Patients? 
The AAPS Journal  2012;14(2):187-195.
Cutaneous microdialysis demonstrates cytokine production in living human skin. In the present study, microdialysis samples taken from uninvolved and lesional skin in three test subjects with psoriasis over 24 h have been investigated for cytokine content with a bead-based multiplex immunoassay from Luminex. Concentration curves for a set of Th1/Th2 and pro-inflammatory cytokines measured differed from a reference group of ten subjects without psoriasis. The time to return to near baseline values after innate insertion reactivity is between 9 and 16 h. Post-equilibration levels (17–24 h) for the three main cytokines elevated in the reference group were differentially elevated outside the range of the reference group for interleukin-1β (IL1β) and IL8 but not so for IL6. Two further cytokines, granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-α not generally elevated in the reference group, showed elevated values in the test subjects. Multivariate time series analysis (chemometry) showed that cytokine patterns for the individual test subjects often fell outside the 99% confidence intervals of a model generated from the reference group. In a clinical research situation, cutaneous microdialysis is feasible, gives generally higher cytokine levels than in the blood and generates interpretable data on an individual’s reactivity compared with a reference group. This may well prove useful in delineation of pathogenetic issues, selection of appropriate therapy and monitoring of subsequent response in inflammatory dermatoses such as psoriasis.
Electronic supplementary material
The online version of this article (doi:10.1208/s12248-012-9331-z) contains supplementary material, which is available to authorized users.
doi:10.1208/s12248-012-9331-z
PMCID: PMC3326164  PMID: 22374383
cytokines; dermis; human; microdialysis; multivariate time series analysis
9.  Physical Activity Attenuates the Effect of Low Birth Weight on Insulin Resistance in Adolescents 
Diabetes  2011;60(9):2295-2299.
OBJECTIVE
To examine whether physical activity influences the association between birth weight and insulin resistance in adolescents.
RESEARCH DESIGN AND METHODS
The study comprised adolescents who participated in two cross-sectional studies: the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study (n = 520, mean age = 14.6 years) and the Swedish part of the European Youth Heart Study (EYHS) (n = 269, mean age = 15.6 years). Participants had valid data on birth weight (parental recall), BMI, sexual maturation, maternal education, breastfeeding, physical activity (accelerometry, counts/minute), fasting glucose, and insulin. Insulin resistance was assessed by homeostasis model assessment–insulin resistance (HOMA-IR). Maternal education level and breastfeeding duration were reported by the mothers.
RESULTS
There was a significant interaction of physical activity in the association between birth weight and HOMA-IR (logarithmically transformed) in both the HELENA study and the EYHS (P = 0.05 and P = 0.03, respectively), after adjusting for sex, age, sexual maturation, BMI, maternal education level, and breastfeeding duration. Stratified analyses by physical activity levels (below/above median) showed a borderline inverse association between birth weight and HOMA-IR in the low-active group (standardized β = −0.094, P = 0.09, and standardized β = −0.156, P = 0.06, for HELENA and EYHS, respectively), whereas no evidence of association was found in the high-active group (standardized β = −0.031, P = 0.62, and standardized β = 0.053, P = 0.55, for HELENA and EYHS, respectively).
CONCLUSIONS
Higher levels of physical activity may attenuate the adverse effects of low birth weight on insulin sensitivity in adolescents. More observational data, from larger and more powerful studies, are required to test these findings.
doi:10.2337/db10-1670
PMCID: PMC3161315  PMID: 21752955
10.  Main characteristics and participation rate of European adolescents included in the HELENA study 
Archives of Public Health  2012;70(1):14.
Background
Participation rate and response rate are key issues in a cross sectional large-scale epidemiological study. The objective of this paper is to describe the study population and to evaluate participation and response rate as well as the key nutritional status variables in male and female adolescents involved in the HELENA study.
Methods
A multi-stage random cluster sampling with a target sample of 3000 adolescents aged [12.5 to 17.5] years, stratified for geographical location and age, was carried out. Information for participants and non-participants (NP) was compared, and participation and response rates to specific questionnaires were discussed.
Results
3,865 adolescents aged [12.5 to 17.5] years (1,845 females) participated in the HELENA study, of whom 1,076 (568 females) participated in the blood sampling. 3,528 (1,845 females) adolescents were finally kept for statistical analysis. Participation rates for the schools and classes differed importantly between countries. The participation rate of pupils within the participating classes also differed importantly between countries. Sex ratio, mean age and BMI were similar between NP and participating adolescents within each centre, and in the overall sample. For all the questionnaires included in the database, the response rate of questionnaires was high (more than 80% of questions were completed).
Conclusion
From this study it could be concluded that participation rate differed importantly between countries, though no bias could be identified when comparing the key study variables between participants and non-participants. Response rate for questionnaires was very high. Future studies investigating lifestyle and health in adolescents can optimize their methods when considering the opportunities and barriers observed in the HELENA study.
doi:10.1186/0778-7367-70-14
PMCID: PMC3490738  PMID: 22958310
11.  Comparison of uniaxial and triaxial accelerometry in the assessment of physical activity among adolescents under free-living conditions: the HELENA study 
Background
Different types of devices are available and the choice about which to use depends on various factors: cost, physical characteristics, performance, and the validity and intra- and interinstrument reliability. Given the large number of studies that have used uniaxial or triaxial devices, it is of interest to know whether the different devices give similar information about PA levels and patterns. The aim of this study was to compare physical activity (PA) levels and patterns obtained simultaneously by triaxial accelerometry and uniaxial accelerometry in adolescents in free-living conditions.
Methods
Sixty-two participants, aged 13-16 years, were recruited in this ancillary study, which is a part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA). All participants wore a uniaxial accelerometer (ActiGraph GT1M®, Pensacola, FL) and a triaxial accelerometer (RT3®, Stayhealthy, Monrovia, CA) simultaneously for 7 days. The patterns were calculated by converting accelerometer data output as a percentage of time spent at sedentary, light, moderate, and vigorous PA per day. Analysis of output data from the two accelerometers were assessed by two different tests: Equivalence Test and Bland & Altman method.
Results
The concordance correlation coefficient between the data from the triaxial accelerometer and uniaxial accelerometer at each intensity level was superior to 0.95. The ANOVA test showed a significant difference for the first three lower intensities while no significant difference was found for vigorous intensity. The difference between data obtained with the triaxial accelerometer and the uniaxial monitor never exceeded 2.1% and decreased as PA level increased. The Bland & Altman method showed good agreement between data obtained between the both accelerometers (p < 0.05).
Conclusions
Uniaxial and triaxial accelerometers do not differ in their measurement of PA in population studies, and either could be used in such studies.
doi:10.1186/1471-2288-12-26
PMCID: PMC3378459  PMID: 22409718
Accelerometers; Human locomotion; Energy expenditure; Youth
12.  Stability of the factorial structure of metabolic syndrome from childhood to adolescence: a 6-year follow-up study 
Background
Metabolic syndrome (MS) is a clustering of cardiometabolic risk factors that is considered a predictor of cardiovascular disease, type 2 diabetes and mortality. There is no consistent evidence on whether the MS construct works in the same way in different populations and at different stages in life.
Methods
We used confirmatory factor analysis to examine if a single-factor-model including waist circumference, triglycerides/HDL-c, insulin and mean arterial pressure underlies metabolic syndrome from the childhood to adolescence in a 6-years follow-up study in 174 Swedish and 460 Estonian children aged 9 years at baseline. Indeed, we analyze the tracking of a previously validated MS index over this 6-years period.
Results
The estimates of goodness-of-fit for the single-factor-model underlying MS were acceptable both in children and adolescents. The construct stability of a new model including the differences from baseline to the end of the follow-up in the components of the proposed model displayed good fit indexes for the change, supporting the hypothesis of a single factor underlying MS component trends.
Conclusions
A single-factor-model underlying MS is stable across the puberty in both Estonian and Swedish young people. The MS index tracks acceptably from childhood to adolescence.
doi:10.1186/1475-2840-10-81
PMCID: PMC3193025  PMID: 21933439
Tracking; Metabolic syndrome; Confirmatory factor analysis
13.  Lactase persistence and milk consumption are associated with body height in Swedish preadolescents and adolescents 
Food & Nutrition Research  2011;55:10.3402/fnr.v55i0.7253.
Background
Body height is a classic polygenic trait. About 80%–90% of height is inherited and 10%–20% owed to environmental factors, of which the most important ones are nutrition and diseases in preadolescents and adolescents.
Objective
The aim of this study was to explore potential relations between the LCT (lactase) C>T-13910 polymorphism, milk consumption, and body height in a sample of Swedish preadolescents and adolescents.
Design
In a cross-sectional study, using a random sample of preadolescents and adolescents (n = 597), dietary intakes were determined. Anthropometric measurements including sexual maturity (Tanner stage) and birth weight were assessed. Parental body height and socio-economic status (SES) were obtained by questionnaires. Genotyping for the LCT C>T-13910 polymorphism that renders individuals lactase persistent (LP) or lactase non-persistent (LNP) was performed by DNA sequencing. Stepwise backward multivariate linear regression was used.
Results
Milk consumption was significantly and positively associated with body height (β = 0.45; 95% CI: 0.040, 0.87, p = 0.032). Adjustments were performed for sex, parental height, birth weight, body mass index (BMI), SES, and Tanner stage. This model explains 90% of the observed variance of body height (adjusted R2 = 0.89). The presence of the -13910 T allele was positively associated with body height (β = 2.05; 95% CI: 0.18, 3.92, p = 0.032).
Conclusions
Milk consumption is positively associated with body height in preadolescents and adolescents. We show for the first time that a nutrigenetic variant might be able to explain in part phenotypic variation of body height in preadolescents and adolescents. Due to the small sample size further studies are needed.
doi:10.3402/fnr.v55i0.7253
PMCID: PMC3169089  PMID: 21909290
LCT-13910 C>T polymorphism; body height; milk consumption; parental body height
14.  Intergenerational Cardiovascular Disease Risk Factors Involve Both Maternal and Paternal BMI 
Diabetes Care  2010;33(4):894-900.
OBJECTIVE
To examine the association between parental BMI and offspring cardiovascular disease (CVD) risk factors.
RESEARCH DESIGN AND METHODS
The study comprised 940 children (9.5 ± 0.4 years) and 873 adolescents (15.5 ± 0.5 years). Parental weight and height were reported by the mother and the father, and BMI was calculated. CVD risk factors included total (sum of five skinfolds) and central (waist circumference) body fat, blood pressure, cardiorespiratory fitness, insulin sensitivity, total cholesterol, HDL cholesterol, triglycerides, and fibrinogen.
RESULTS
Maternal and paternal BMI were positively associated with total and central fatness in offspring (P < 0.001). BMIs of both parents were significantly related to fibrinogen levels (P < 0.02), but these associations disappeared when controlling for fatness. There was a positive relationship between maternal and paternal BMI and waist circumference in the offspring regardless of total adiposity and height (P < 0.001). Maternal BMI was negatively associated with offspring cardiorespiratory fitness independently of fatness (P < 0.02). These relationships persisted when overweight descendants were excluded from the analysis. There were no significant associations between parental BMI and the other CVD risk factors.
CONCLUSIONS
Both maternal and paternal BMI increase CVD risk factors of their offspring, characterized by total and central body fat, and higher maternal BMI was associated with poorer cardiorespiratory fitness. Our findings give further support to the concept that adiposity in parents transmits susceptibility to CVD risk to descendants, which is detectable even in the absence of overweight in offspring.
doi:10.2337/dc09-1878
PMCID: PMC2845048  PMID: 20056951
15.  Relationship between self-reported dietary intake and physical activity levels among adolescents: The HELENA study 
Background
Evidence suggests possible synergetic effects of multiple lifestyle behaviors on health risks like obesity and other health outcomes. Therefore it is important to investigate associations between dietary and physical activity behavior, the two most important lifestyle behaviors influencing our energy balance and body composition. The objective of the present study is to describe the relationship between energy, nutrient and food intake and the physical activity level among a large group of European adolescents.
Methods
The study comprised a total of 2176 adolescents (46.2% male) from ten European cities participating in the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study. Dietary intake and physical activity were assessed using validated 24-h dietary recalls and self-reported questionnaires respectively. Analyses of covariance (ANCOVA) were used to compare the energy and nutrient intake and the food consumption between groups of adolescents with different physical activity levels (1st to 3rd tertile).
Results
In both sexes no differences were found in energy intake between the levels of physical activity. The most active males showed a higher intake of polysaccharides, protein, water and vitamin C and a lower intake of saccharides compared to less active males. Females with the highest physical activity level consumed more polysaccharides compared to their least active peers. Male and female adolescents with the highest physical activity levels, consumed more fruit and milk products and less cheese compared to the least active adolescents. The most active males showed higher intakes of vegetables and meat, fish, eggs, meat substitutes and vegetarian products compared to the least active ones. The least active males reported the highest consumption of grain products and potatoes. Within the female group, significantly lower intakes of bread and cereal products and spreads were found for those reporting to spend most time in moderate to vigorous physical activity. The consumption of foods from the remaining food groups, did not differ between the physical activity levels in both sexes.
Conclusion
It can be concluded that dietary habits diverge between adolescents with different self-reported physical activity levels. For some food groups a difference in intake could be found, which were reflected in differences in some nutrient intakes. It can also be concluded that physically active adolescents are not always inclined to eat healthier diets than their less active peers.
doi:10.1186/1479-5868-8-8
PMCID: PMC3045277  PMID: 21294914
16.  Metabolite Signature during Short-Day Induced Growth Cessation in Populus  
The photoperiod is an important environmental signal for plants, and influences a wide range of physiological processes. For woody species in northern latitudes, cessation of growth is induced by short photoperiods. In many plant species, short photoperiods stop elongational growth after a few weeks. It is known that plant daylength detection is mediated by Phytochrome A (PHYA) in the woody hybrid aspen species. However, the mechanism of dormancy involving primary metabolism remains unclear. We studied changes in metabolite profiles in hybrid aspen leaves (young, middle, and mature leaves) during short-day-induced growth cessation, using a combination of gas chromatography–time-of-flight mass spectrometry, and multivariate projection methods. Our results indicate that the metabolite profiles in mature source leaves rapidly change when the photoperiod changes. In contrast, the differences in young sink leaves grown under long and short-day conditions are less distinct. We found short daylength induced growth cessation in aspen was associated with rapid changes in the distribution and levels of diverse primary metabolites. In addition, we conducted metabolite profiling of leaves of PHYA overexpressor (PHYAOX) and those of the control to find the discriminative metabolites between PHYAOX and the control under the short-day conditions. The metabolite changes observed in PHYAOX leaves, together with those in the source leaves, identified possible candidates for the metabolite signature (e.g., 2-oxo-glutarate, spermidine, putrescine, 4-amino-butyrate, and tryptophan) during short-day-induced growth cessation in aspen leaves.
doi:10.3389/fpls.2011.00029
PMCID: PMC3355535  PMID: 22629261
aspen; Phytochrome A; metabolite profiling; GC–TOF-MS; dormancy; growth cessation
17.  Early Life Programming of Abdominal Adiposity in Adolescents: The HELENA Study 
Diabetes Care  2009;32(11):2120-2122.
OBJECTIVE
To examine the relationship between birth weight and abdominal adiposity in adolescents.
RESEARCH DESIGN AND METHODS
A total of 284 adolescents (49.3% of whom were female) aged 14.9 ± 1.2 years were included in the study. Birth weight and gestational age were obtained from parental records. Abdominal adiposity (in three regions: R1, R2, and R3) and trunk and total body fat mass were measured by dual-energy X-ray absorptiometry. Regional fat mass indexes (FMIs) were thereafter calculated as fat mass divided by the square of height (Trunk FMI and abdominal FMI R1, R2, and R3).
RESULTS
Birth weight was negatively associated with abdominal FMI R1, R2, and R3 independently of total fat mass, gestational age, sex, breast-feeding duration, pubertal stage, physical activity, and socioeconomic status (all P < 0.01).
CONCLUSIONS
Our study shows an inverse association between birth weight and abdominal adiposity in adolescents independently of total fat mass and other potential confounders. These findings suggest that fetal nutrition, as reflected by birth weight, may have a programming effect on abdominal adiposity later in life.
doi:10.2337/dc09-0983
PMCID: PMC2768211  PMID: 19641158
18.  Body fat and dairy product intake in lactase persistent and non-persistent children and adolescents 
Food & Nutrition Research  2010;54:10.3402/fnr.v54i0.5141.
Background
Lactase non-persistent (LNP) individuals may be lactose intolerant and therefore on a more restricted diet concerning milk and milk products compared to lactase persistent (LP) individuals. This may have an impact on body fat mass.
Objective
This study examines if LP and LNP children and adolescents, defined by genotyping for the LCT-13910 C > T polymorphism, differ from each other with regard to milk and milk product intake, and measures of body fat mass.
Design
Children (n=298, mean age 9.6 years) and adolescents (n=386, mean age 15.6 years), belonging to the Swedish part of the European Youth Heart Study, were genotyped for the LCT-13910 C > T polymorphism. Dietary intakes of reduced and full-fat dairy varieties were determined.
Results
LNP (CC genotype) subjects consumed less milk, soured milk and yoghurt compared to LP (CT/TT genotype) subjects (p<0.001). Subsequent partitioning for age group attenuated this observation (p=0.002 for children and p=0.023 in adolescents). Six subjects were reported by parents to be ‘lactose intolerant’, none of whom were LNP. LNP children and adolescents consumed significantly less reduced fat milk and milk products than LP children and adolescents (p=0.009 for children and p=0.001 for adolescents).
Conclusions
We conclude that LP is linked to an overall higher milk and dairy intake, but is not linked to higher body fat mass in children and adolescents.
doi:10.3402/fnr.v54i0.5141
PMCID: PMC2887755  PMID: 20585563
milk consumption; lactose intolerance; LCT-13910 C > T polymorphism; obesity; nutrigenetics
19.  Measuring physical activity-related environmental factors: reliability and predictive validity of the European environmental questionnaire ALPHA 
Background
A questionnaire to assess physical activity related environmental factors in the European population (a 49-item and an 11-item version) was created as part of the framework of the EU-funded project "Instruments for Assessing Levels of PHysical Activity and fitness (ALPHA)". This paper reports on the development and assessment of the questionnaire's test-retest stability, predictive validity, and applicability to European adults.
Methods
The first pilot test was conducted in Belgium, France and the UK. In total 190 adults completed both forms of the ALPHA questionnaire twice with a one-week interval. Physical activity was concurrently measured (i) by administration of the long version of the International Physical Activity Questionnaire (IPAQ) by interview and (ii) by accelerometry (Actigraph™ device). After adaptations, the second field test took place in Belgium, the UK and Austria; 166 adults completed the adapted questionnaire at two time points, with minimum one-week interval. In both field studies intraclass correlation coefficients (ICC) and proportion of agreement were computed to assess the stability of the two test scores. Predictive validity was examined in the first field test by correlating the results of the questionnaires with physical activity data from accelerometry and long IPAQ-last 7 days.
Results
The reliability scores of the ALPHA questionnaire were moderate-to good in the first field testing (ICC range 0.66 - 0.86) and good in the second field testing (ICC range 0.71 - 0.87). The proportion of agreement for the ALPHA short increased significantly from the first (range 50 - 83%) to the second field testing (range 85 - 95%). Environmental scales from both versions of the ALPHA questionnaire were significantly associated with self-reported minutes of transport-related walking, and objectively measured low intensity physical activity levels, particularly in women. Both versions were easily administered with an average completion time of six minutes for the 49-item version and less than two minutes for the short version.
Conclusion
The ALPHA questionnaire is an instrument to measure environmental perceptions in relation to physical activity. It appears to have good reliability and predictive validity. The questionnaire is now available to other researchers to investigate its usefulness and applicability across Europe.
doi:10.1186/1479-5868-7-48
PMCID: PMC2892430  PMID: 20504339
20.  The tracking of dietary intakes of children and adolescents in Sweden over six years: the European Youth Heart Study 
Background
The stability of dietary habits through various life-stages is not well understood. A better understanding of the tracking of diet over time could have implications for health promotion as well as for the planning of nutritional epidemiology studies. We examined the stability of dietary intakes of children and adolescents over six years.
Methods
As part of the European Youth Heart Study, in 1998-9, a 24-h dietary recall was performed on over one thousand 9- and 15-year-olds in Sweden. In 2004-5, 40% returned to the follow-up study. These 452 subjects (273 15- and 179 21-year-olds) were assigned to age- and gender-specific tertiles of intakes of food groups, energy, selected nutrients and energy density (low, mid and high) at each time point. The agreement between the classification of subjects into tertiles at both time points was examined using Cohen's weighted κ and other stability coefficients. We included a dropout analysis and considered the effect that energy mis-reporting might have on our results.
Results
Fair tracking was seen between childhood and adolescence for the milk, fil and yoghurt food group (κ = 0.30), and between adolescence and young adulthood for fruit (κ = 0.24). Slight tracking was observed for most other food groups and fair to slight tracking for all nutrients studied. Only membership of the high milk, fil and yoghurt tertile could be predicted from membership at baseline, in children. Excluding potential energy mis-reporters did not affect the results.
Conclusions
Despite the long time between data collections, and the method of dietary data collection used, evidence for slight tracking was observed for most food groups and nutrients over these six years.
doi:10.1186/1479-5868-6-91
PMCID: PMC2797763  PMID: 20003331
21.  Improved ability of biological and previous caries multimarkers to predict caries disease as revealed by multivariate PLS modelling 
BMC Oral Health  2009;9:28.
Background
Dental caries is a chronic disease with plaque bacteria, diet and saliva modifying disease activity. Here we have used the PLS method to evaluate a multiplicity of such biological variables (n = 88) for ability to predict caries in a cross-sectional (baseline caries) and prospective (2-year caries development) setting.
Methods
Multivariate PLS modelling was used to associate the many biological variables with caries recorded in thirty 14-year-old children by measuring the numbers of incipient and manifest caries lesions at all surfaces.
Results
A wide but shallow gliding scale of one fifth caries promoting or protecting, and four fifths non-influential, variables occurred. The influential markers behaved in the order of plaque bacteria > diet > saliva, with previously known plaque bacteria/diet markers and a set of new protective diet markers. A differential variable patterning appeared for new versus progressing lesions. The influential biological multimarkers (n = 18) predicted baseline caries better (ROC area 0.96) than five markers (0.92) and a single lactobacilli marker (0.7) with sensitivity/specificity of 1.87, 1.78 and 1.13 at 1/3 of the subjects diagnosed sick, respectively. Moreover, biological multimarkers (n = 18) explained 2-year caries increment slightly better than reported before but predicted it poorly (ROC area 0.76). By contrast, multimarkers based on previous caries predicted alone (ROC area 0.88), or together with biological multimarkers (0.94), increment well with a sensitivity/specificity of 1.74 at 1/3 of the subjects diagnosed sick.
Conclusion
Multimarkers behave better than single-to-five markers but future multimarker strategies will require systematic searches for improved saliva and plaque bacteria markers.
doi:10.1186/1472-6831-9-28
PMCID: PMC2780985  PMID: 19886991
22.  Assessment of environmental correlates of physical activity: development of a European questionnaire 
Background
Research on the influence of the physical environment on physical activity is rapidly expanding and different measures of environmental perceptions have been developed, mostly in the US and Australia. The purpose of this paper is to (i) provide a literature review of measures of environmental perceptions recently used in European studies and (ii) develop a questionnaire for population monitoring purposes in the European countries.
Methods
This study was done within the framework of the EU-funded project 'Instruments for Assessing Levels of Physical Activity and Fitness (ALPHA)', which aims to propose standardised instruments for physical activity and fitness monitoring across Europe. Quantitative studies published from 1990 up to November 2007 were systematically searched in Pubmed, Web of Science, TRIS and Geobase. In addition a survey was conducted among members of the European network for the promotion of Health-Enhancing Physical Activity (HEPA Europe) and European members of the International Physical Activity and Environment Network (IPEN) to identify published or ongoing studies. Studies were included if they were conducted among European general adult population (18+y) and used a questionnaire to assess perceptions of the physical environment. A consensus meeting with an international expert group was organised to discuss the development of a European environmental questionnaire.
Results
The literature search resulted in 23 European studies, 15 published and 8 unpublished. In these studies, 13 different environmental questionnaires were used. Most of these studies used adapted versions of questionnaires that were developed outside Europe and that focused only on the walkability construct: The Neighborhood Environment Walkability Scale (NEWS), the abbreviated version of the NEWS (ANEWS) and the Neighborhood Quality of Life Study (NQLS) questionnaire have been most commonly used. Based on the results of the literature review and the output of the meeting with international experts, a European environmental questionnaire with 49 items was developed.
Conclusion
There is need for a greater degree of standardization in instruments/methods used to assess environmental correlates of physical activity, taking into account the European-specific situation. A first step in this process is taken by the development of a European environmental questionnaire.
doi:10.1186/1479-5868-6-39
PMCID: PMC2713198  PMID: 19580645
23.  The association between health enhancing physical activity and neighbourhood environment among Swedish adults – a population-based cross-sectional study 
Background
This study examines the relationship of neighbourhood environment factors with walking and total health enhancing physical activity.
Methods
A population-based cross-sectional study. The short self-administered version of the validated International Physical Activity Questionnaire (IPAQ) was used to assess health enhancing physical activity including walking. The neighbourhood environment was assessed using a 17-item environmental module. A principal component analysis among the environmental variables was conducted. The factor scores were divided into tertiles and independent associations between factor tertiles and physical activity categories and walking were studied by multinomial logistic regression with adjustment for confounders.
Results
In adjusted models, a lower odds ratio (OR) for reaching the middle, OR: 0.66 (95% Confidence Interval (CI): 0.47–0.98), and upper, OR: 0.65 (0.45–0.95), tertile of walking was observed among those in the lowest tertile of the degree of urbanisation. A higher OR for reaching the middle, OR: 1.84 (1.28–1.64), and upper tertile, OR: 1.64 (1.14–2.36), of walking was observed among those in the lowest tertile of fear of crime. A higher OR for reaching the high category of total health enhancing physical activity was observed among those in the lowest, OR: 2.01 (1.32–3.05), and middle tertile, OR: 1.52 (1.02–2.25), of the factor degree of urbanisation.
Conclusion
The findings suggest that the environment is differentially related to walking and total health enhancing physical activity. This should be explored in future research to disentangle the complex relationship between different levels and aspects of physical activity and their relationship with the environment.
doi:10.1186/1479-5868-6-8
PMCID: PMC2647520  PMID: 19203354
24.  Birth weight and blood lipid levels in Spanish adolescents: Influence of selected APOE, APOC3 and PPARgamma2 gene polymorphisms. The AVENA Study 
BMC Medical Genetics  2008;9:98.
Background
There is increasing evidence indicating that genes involved in certain metabolic processes of cardiovascular diseases may be of particular influence in people with low body weight at birth. We examined whether the apolipoprotein (APO) E, APOC3 and the peroxisome proliferator-activated receptor-γ-2 (PPARγ2) polymorphisms influence the association between low birth weight and blood lipid levels in healthy adolescents aged 13–18.5 years.
Methods
A cross-sectional study of 502 Spanish adolescents born at term was conducted. Total (TC) and high density lipoprotein cholesterol (HDLc), triglycerides (TG), apolipoprotein (apo) A and B, and lipoprotein(a) [Lp(a)] were measured. Low density lipoprotein cholesterol (LDLc), TC-HDLc, TC/HDLc and apoB/apoA were calculated.
Results
Low birth weight was associated with higher levels of TC, LDLc, apoB, Lp(a), TC-HDLc, TC/HDLc and apoB/apoA in males with the APOE ε3ε4 genotype, whereas in females, it was associated with lower HDLc and higher TG levels. In males with the APOC3 S1/S2 genotype, low birth weight was associated with lower apoA and higher Lp(a), yet this association was not observed in females. There were no associations between low birth weight and blood lipids in any of the PPARγ2 genotypes.
Conclusion
The results indicate that low birth weight has a deleterious influence on lipid profile particularly in adolescents with the APOE ε3/ε4 genotype. These findings suggest that intrauterine environment interact with the genetic background affecting the lipid profile in later life.
doi:10.1186/1471-2350-9-98
PMCID: PMC2615435  PMID: 19000312
25.  Adherence to physical activity recommendations and the influence of socio-demographic correlates – a population-based cross-sectional study 
BMC Public Health  2008;8:367.
Background
Current physical activity guidelines acknowledge the importance of total health enhancing physical activity (HEPA) compared to leisure time physical activity or exercise alone. Assessing total HEPA may result in different levels of adherence to these as well as the strength and/or direction of associations observed between total HEPA and socio-demographic correlates. The aim of this study was to estimate the proportion of the population adhering to the recommendation of at least 30 minutes of HEPA on most days, and to examine the influences of socio-demographic correlates on reaching this recommendation.
Methods
Swedish adults aged 18–74 years (n = 1470) were categorized, based on population data obtained using the IPAQ, into low, moderately and highly physically active categories. Independent associations between the physical activity categories and socio-demographic correlates were studied using a multinomial logistic regression.
Results
Of the subjects, 63% (95% CI: 60.5–65.4) adhered to the HEPA recommendation. Most likely to reach the highly physical active category were those aged < 35 years (OR = 1.8; 95% CI: 1.1–3.3), living in small towns (OR = 1.8; 95% CI: 1.1–2.7) and villages (OR = 2.4; 95% CI: 1.6–3.7), having a BMI between 25.0–29.9 kg/m2 (OR = 2.7; 95% CI: 1.4–5.3) having a BMI < 25 kg/m2 (OR = 2.5; 95% CI: 1.3–4.9), or having very good (OR = 2.1; 95% CI: 1.3–3.3) or excellent self-perceived health (OR = 4.1; 95% CI: 2.4–6.8). Less likely to reach the high category were women (OR = 0.6; 95% CI: 0.5–0.9) and those with a university degree (OR = 0.5; 95% CI: 0.3–0.9). Similar, but less pronounced associations were observed for the moderate group. Gender-specific patterns were also observed.
Conclusion
Almost two-thirds of the Swedish adult population adhered to the physical activity recommendation. Due to a large diversity in levels of physical activity among population subgroups, social-ecological approaches to physical activity promotion may be warranted.
doi:10.1186/1471-2458-8-367
PMCID: PMC2576236  PMID: 18945354

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