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41.
42.
Claudia Semmler Jo Ashcroft Cornelia H.M. van Jaarsveld Susan Carnell Jane Wardle 《Obesity (Silver Spring, Md.)》2009,17(4):814-820
The purpose of the study was to test the hypothesis that socioeconomic status (SES) moderates the association between parental weight and changes in BMI from childhood to early adolescence. Participants included 428 twin children from 100 families with obese parents (“obese families”) and 114 sociodemographically matched families with normal‐weight parents (“lean families”) who were assessed in their homes (age = 4.4). Follow‐up study was conducted 7 years later (age = 11.2) on 346 children (81%). Complete data were available for 333 children. Family SES was indexed with maternal education. Children's weights and heights were measured to calculate BMI s.d. scores based on 1990 British norms. Overweight was defined as >91st BMI centile. In children with obese parents, BMI s.d. scores increased from 0.51 at age 4 to 1.06 at age 11. In children with lean parents, BMI s.d. scores decreased from 0.11 to 0.05. Prevalence of overweight remained stable from age 4 to 11 in children with lean parents (8% to 9%), but it more than doubled in children with obese parents (17% to 45%). There was a significant interaction between parental weight and family SES (P < 0.01), so that in children with lean parents there was no SES difference in the BMI status from age 4 to 11; however, in children with obese parents, the increase in adiposity was significantly greater in lower SES families. These results suggest that parental leanness confers significant protection against development of overweight in children regardless of family SES, while parental obesity is an adverse prognostic sign, especially in lower SES families. 相似文献
43.
P P van Jaarsveld H Edelhoch D S Goodman J Robbins 《The Journal of biological chemistry》1973,248(13):4698-4705
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45.
P.B. Kruger C.F. De V. Albrecht P.P. Van Jaarsveld 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1993,612(2)
A novel approach has been developed for direct injection of physiological fluids on an in-line extraction pre-column followed by column switching in order to introduce the adsorbed xenobiotic onto the analytical column. The physiological fluid is pre-treated with guanidinium solution in water (200 μl of fluid plus 300 μl of a reagent containing 8.05 M guanidinium and 1.02 M ammonium sulfate) in order to denature protein binding sites and to serve as a universal solvent for a divergent range of polar to non-polar xenobiotics in a hydrophilic medium. A 0.5 M ammonium sulfate solution (500 μl) is used as a pre- and post-flush reagent for the extraction pre-column (30 mm × 2.1 mm I.D.). The pre-flush reagent prepares the sorbent environment of the C18 pre-column for the hydrophobic retention of analytes. The post-flush reagent flushes non-retained sample proteins and salts to waste prior to switching the pre-column in-line with the analytical column. Universal chromatographic conditions for the analytical phase allows elution of a range of polar to non-polar xenobiotics within 20 min from an end-capped C8 silica anaytical column (250 mm × 4.6 mm I.D.). This is effected by a linear gradient from a binary system consisting of solvent A (0.05 M KH2PO4) and solvent B (acetonitrile—isopropanol, 80:20, v/v). 相似文献
46.
47.
Environmental Influences on Children's Physical Activity: Quantitative Estimates Using a Twin Design
Background
Twin studies offer a ‘natural experiment’ that can estimate the magnitude of environmental and genetic effects on a target phenotype. We hypothesised that fidgetiness and enjoyment of activity would be heritable but that objectively-measured daily activity would show a strong shared environmental effect.Methodology/Principal Findings
In a sample of 9–12 year-old same-sex twin pairs (234 individuals; 57 MZ, 60 DZ pairs) we assessed three dimensions of physical activity: i) objectively-measured physical activity using accelerometry, ii) ‘fidgetiness’ using a standard psychometric scale, and iii) enjoyment of physical activity from both parent ratings and children''s self-reports. Shared environment effects explained the majority (73%) of the variance in objectively-measured total physical activity (95% confidence intervals (CI): 0.63–0.81) with a smaller unshared environmental effect (27%; CI: 0.19–0.37) and no significant genetic effect. In contrast, fidgetiness was primarily under genetic control, with additive genetic effects explaining 75% (CI: 62–84%) of the variance, as was parent''s report of children''s enjoyment of low 74% (CI: 61–82%), medium 80% (CI: 71–86%), and high impact activity (85%; CI: 78–90%), and children''s expressed activity preferences (60%, CI: 42–72%).Conclusions
Consistent with our hypothesis, the shared environment was the dominant influence on children''s day-to-day activity levels. This finding gives a strong impetus to research into the specific environmental characteristics influencing children''s activity, and supports the value of interventions focused on home or school environments. 相似文献48.
van Jaarsveld AS Biggs R Scholes RJ Bohensky E Reyers B Lynam T Musvoto C Fabricius C 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2005,360(1454):425-441
The Southern African Millennium Ecosystem Assessment (SAfMA) evaluated the relationships between ecosystem services and human well-being at multiple scales, ranging from local through to sub-continental. Trends in ecosystem services (fresh water, food, fuel-wood, cultural and biodiversity) over the period 1990-2000 were mixed across scales. Freshwater resources appear strained across the continent with large numbers of people not securing adequate supplies, especially of good quality water. This translates to high infant mortality patterns across the region. In some areas, the use of water resources for irrigated agriculture and urban-industrial expansion is taking place at considerable cost to the quality and quantity of freshwater available to ecosystems and for domestic use. Staple cereal production across the region has increased but was outstripped by population growth while protein malnutrition is on the rise. The much-anticipated wood-fuel crisis on the subcontinent has not materialized but some areas are experiencing shortages while numerous others remain vulnerable. Cultural benefits of biodiversity are considerable, though hard to quantify or track over time. Biodiversity resources remain at reasonable levels, but are declining faster than reflected in species extinction rates and appear highly sensitive to land-use decisions. The SAfMA sub-global assessment provided an opportunity to experiment with innovative ways to assess ecosystem services including the use of supply-demand surfaces, service sources and sink areas, priority areas for service provision, service 'hotspots' and trade-off assessments. 相似文献
49.
M H Ricketts K Schulz A van Zyl A J Bester C D Boyd H Meinhold P P van Jaarsveld 《The Journal of heredity》1985,76(1):12-16
Congenital goiter was reported in a number of herds of Afrikander cattle in the 1950's. Some affected animals were assembled and maintained as a closed herd. Although considerable biochemical research into the nature of the disease has been conducted, no definitive report has described the mode of inheritance of the defect. This paper presents the results of breeding studies that indicate the defect is inherited as an autosomal recessive. Southern blot analysis of the thyroglobulin gene confirms this finding. In addition, serum levels of TSH (thyroid stimulating hormone, thyrotropin), T3 (3,4,3'-tri-iodothyronine), T4 (thyroxine), rT3 (3,3',5'-tri-iodothyronine), and DIT (diiodotyrosine) of goitrous animals are compared with normal animals. 相似文献
50.
M C Mhatre A S van Jaarsveld R J Reiter 《Biochemical and biophysical research communications》1988,153(3):1186-1192
NAT, HIOMT and melatonin are described in the extra-orbital lacrimal glands. The extra-orbital lacrimal glands of female Syrian hamsters contain higher NAT activity and melatonin levels than those in male glands, while male glands have higher HIOMT activity. Castration did not change melatonin in the lacrimal glands, although NAT and HIOMT activities were altered. The exposure of female hamsters to light in the morning (0600h) was associated with a reduction in both NAT activity and melatonin levels. Porphyrins were not detected in the lacrimal glands of either male or female hamsters. 相似文献