A mediation analysis on the relationship between dietary glycemic load, obesity and cardiovascular risk factors in children.

BACKGROUND/OBJECTIVE: Adiposity may mediate the effect of dietary glycemic load (GL) on lipid profiles in children, as studies have shown an association between dietary GL and adiposity and between adiposity and lipid profiles. Our objective was to evaluate the role of adiposity as a mediator in the association between dietary GL and lipid profiles after 2 years. SUBJECTS/METHODS: The Quebec Adipose and Lifestyle InvesTigation in Youth study included 630 children, 8-10 years old at recruitment with at least one parent with overweight or obesity with 2-year follow-up. Three baseline 24-h dietary recalls were administered by a dietitian at baseline. Child and parent characteristics were obtained through direct measurement (blood lipids, anthropometrics) or questionnaires (socio-economic characteristics). Indicators of adiposity, including body mass index (BMI) z-score and percent body fat, were the mediators of interest. A conventional approach using the Baron and Kenny method was used. A causal approach using marginal structural models (MSM) was used to estimate the controlled direct effect. RESULTS: Mean age at baseline was 9.6 years and 33% were overweight or obese. Both methods revealed that the effect of GL on blood lipids was mediated by adiposity. The weighted MSM did not show evidence of a direct effect (TG: ß =;0.01, 95% CI = -0.01,0.02; HDL: ß = 0.005, 95%CI = -0.002,0.01), whereas the conventional method did for TG but not HDL (TG:ß = 0.04, 95%CI = 0.01,0.07; HDL: ß = -0.01, 95%CI = -0.03,0.01). CONCLUSION: Adiposity contributes substantially to the association between GL and blood lipids. The choice of approach for mediation analysis should be based on the fulfilment of conditions of each method.

The Cardiometabolic Risk Profile of Underreporters of Energy Intake Differs from That of Adequate Reporters among Children at Risk of Obesity.

Background: Misreporting of energy intake (EI) in nutritional epidemiology is a concern because of information bias, and tends to occur differentially in obese compared with nonobese subjects. Objective: We examined characteristics of misreporters within a cohort of children with a parental history of obesity and the bias introduced by underreporting. Methods: The QUebec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort included 630 Caucasian children aged 8-10 y at recruitment with ≥1 obese parent [body mass index (BMI; in kg/m2) >30 or waist circumference >102 cm (men), >88 cm (women)] and free of diabetes or severe illness. Children on antihypertensive medications or following a restricted diet were excluded. Child and parent characteristics were measured directly or by questionnaire. Three 24-h dietary recalls were administered by phone by a dietitian. Goldberg's cutoff method identified underreporters (URs). Logistic regression identified correlates of URs. We compared coefficients from linear regressions of BMI after 2 y on total EI at baseline 1) in all participants; 2) in adequate reporters (ARs) (excluding URs); 3) in all participants statistically adjusted for underreporting; 4) excluding URs using individual physical activity level (PAL)-specific cutoffs; and 5) in all participants statistically adjusted for underreporting using PAL-specific cutoffs. Results: We identified 175 URs based on a calculated cutoff of 1.11. URs were older, had a higher BMI z score, and had poorer cardiometabolic health indicators. Parents of URs had a lower family income and higher BMI. Child BMI z score (OR: 3.07; 95% CI: 2.38, 3.97) and age (OR: 1.46/y; 95% CI: 1.14, 1.87/y) were the strongest correlates of underreporting. The association between BMI and total EI was null in all participants but became significantly positive after excluding URs (ß = 0.62/1000 kcal; 95% CI: 0.33, 0.92/1000 kcal) and after adjustment for URs (ß = 0.85/1000 kcal; 95% CI: 0.55, 1.06/1000 kcal). Conclusions: URs in 8- to 10-y-old children differed from ARs. Underreporting biases measurement of nutritional exposures and the assessment of exposure-outcome relations. Identifying URs and using an appropriate correction method is essential.

Understanding how Indigenous culturally-based interventions can improve participants' health in Canada.

There is increasing recognition that culturally-based diabetes prevention programs can facilitate the adoption and maintenance of healthy behaviours in the communities in which they are implemented. The Kahnawake School Diabetes Prevention Project (KSDPP) is a health promotion, community-based participatory research project aiming to reduce the incidence of Type 2 diabetes in the community of Kahnawake (Mohawk territory, Canada), with a large range of interventions integrating a Haudenosaunee perspective of health. Building on a qualitative, naturalistic and interpretative inquiry, this study aimed to assess the outcomes of a suite of culturally-based interventions on participants' life and experience of health. Data were collected through semi-structured qualitative interviews of 1 key informant and 17 adult, female Kahnawake community members who participated in KSDPP's suite of interventions from 2007 to 2010. Grounded theory was chosen as an analytical strategy. A theoretical framework that covered the experiences of all study participants was developed from the grounded theory analysis. KSDPP's suite of interventions provided opportunities for participants to experience five different change processes: (i) Learning traditional cooking and healthy eating; (ii) Learning physical activity; (iii) Learning mind focusing and breathing techniques; (iv) Learning cultural traditions and spirituality; (v) Socializing and interacting with other participants during activities. These processes improved participants' health in four aspects: mental, physical, spiritual and social. Results of this study show how culturally-based health promotion can bring about healthy changes addressing the mental, physical, spiritual and social dimensions of a holistic concept of health, relevant to the Indigenous perspective of well-being.

Reliability of length measurements collected by community nurses and health volunteers in rural growth monitoring and promotion services.

BACKGROUND: Length measurements are important in growth, monitoring and promotion (GMP) for the surveillance of a child's weight-for-length and length-for-age. These two indices provide an indication of a child's risk of becoming wasted or stunted, and are more informative about a child's growth than the widely used weight-for-age index (underweight). Although the introduction of length measurements in GMP is recommended by the World Health Organization, concerns about the reliability of length measurements collected in rural outreach settings have been expressed by stakeholders. Our aim was to describe the reliability and challenges associated with community health personnel measuring length for rural outreach GMP activities. METHODS: Two reliability studies (A and B), using 10 children less than 24 months each, were conducted in the GMP services of a rural district in Ghana. Fifteen nurses and 15 health volunteers (HV) with no prior experience in length measurements were trained. Intra- and inter-observer technical error of measurement (TEM), average bias from expert anthropometrist, and coefficient of reliability (R) of length measurements were assessed and compared across sessions. Observations and interviews were used to understand the ability and experiences of health personnel with measuring length at outreach GMP. RESULTS: Inter-observer TEM was larger than intra-observer TEM for both nurses and HV at both sessions and was unacceptably (compared to error standards) high in both groups at both time points. Average biases from expert's measurements were within acceptable limits, however, both groups tended to underestimate length measurements. The R for lengths collected by nurses (92.3%) was higher at session B compared to that of HV (87.5%). Length measurements taken by nurses and HV, and those taken by an experienced anthropometrist at GMP sessions were of moderate agreement (kappa = 0.53, p < 0.0001). CONCLUSIONS: The reliability of length measurements improved after two refresher trainings for nurses but not for HV. In addition, length measurements taken during GMP sessions may be susceptible to errors due to overburdened health personnel and crowded GMP clinics. There is need for both pre- and in-service training of nurses and HV on length measurements and procedures to improve reliability of length measurements.

School food environments associated with adiposity in Canadian children.

BACKGROUND/OBJECTIVES: Targeting obesogenic features of children's environment that are amenable to change represents a promising strategy for health promotion. The school food environment, defined as the services and policies regarding nutrition and the availability of food in the school and surrounding neighborhood, is particularly important given that students travel through the school neighborhood almost daily and that they consume a substantial proportion of their calories at school. SUBJECTS/METHODS: As part of the Quebec Adipose and Lifestyle Investigation in Youth (QUALITY) cohort study, we assessed features of school indoor dietary environment and the surrounding school neighborhoods, when children were aged 8-10 years (2005-2008). School principals reported on food practices and policies within the schools. The density of convenience stores and fast-food outlets surrounding the school was computed using a Geographical Information System. Indicators of school neighborhood deprivation were derived from census data. Adiposity outcomes were measured in a clinical setting 2 years later, when participants were aged 10-12 years (2008-2011). We conducted cluster analyses to identify school food environment types. Associations between school types and adiposity were estimated in linear regression models. RESULTS: Cluster analysis identified three school types with distinct food environments. Schools were characterized as: overall healthful (45%); a healthful food environment in the surrounding neighborhood, but an unhealthful indoor food environment (22%); or overall unhealthful (33%). Less healthful schools were located in more deprived neighborhoods and were associated with greater child adiposity. CONCLUSIONS: Despite regulatory efforts to improve school food environments, there is substantial inequity in dietary environments across schools. Ensuring healthful indoor and outdoor food environments across schools should be included in comprehensive efforts to reduce obesity-related health disparities.

A prospective evaluation of the depression-nutrient intake reverse causality hypothesis in a cohort of community-dwelling older Canadians.

Studies have investigated the potential protective effects that diet may have on late-life depression incidence. This disorder can, however, affect the person's food intake, widely known as the reverse causality hypothesis of depression. To test this hypothesis, we compared mean nutrient intakes from three 24-h recalls during the year depression was detected (Geriatric Depression Scale ≥11 or antidepressant medication) with intakes from 1 year earlier among community-dwelling older adults (67-83 years) followed up annually in the 4-year Québec Longitudinal Study on Nutrition and Aging, who were free of depression and cognitive impairment at baseline. Participants (n 158, 64·4 % female) who became depressed and had data available for all follow-up years were matched by age group and sex with non-depressed participants. General linear mixed models were adjusted for percentage changes in physical activity, functional autonomy and stressful life events reported at the time of positive screening. A significant group effect for the dietary intake of all three B-vitamins was observed, as depression cases had consistently lower dietary intakes than controls (P<0·01). Over time, intakes of dietary vitamin B12 declined within depressed participants in bivariate analysis, but there was no time×group effect for any nutrient tested in the multivariate analyses. Intakes of energy, protein, saturated fat and total dietary fibre did not change in cases v. CONTROLS: Among community-dwelling older adults, declines in dietary vitamins B6, B12 and folate may precede depression incidence. To help preventative efforts by programmes and practitioners, longitudinal cohorts of longer duration should investigate the extent of the decline in dietary intakes relative to the time of depression.

Diet quality as measured by the Diet Quality Index-International is associated with prospective changes in body fat among Canadian children.

OBJECTIVE: To quantify the association of dietary quality with prospective changes in adiposity. DESIGN: Children participating in the QUALITY (QUebec Adipose and Lifestyle InvesTigation in Youth) study underwent examination at baseline and at 2-year follow-up. Dietary quality was assessed by the Diet Quality Index-International (DQII) using three non-consecutive 24 h diet recalls at baseline. The DQII has four main categories: dietary adequacy, variety, moderation and overall balance. Fat mass index (FMI; [fat mass (kg)]/[height (m)]2), central FMI (CFMI; [trunk fat mass (kg)]/[height (m)]2), percentage body fat (%BF; [total fat mass (kg)]/[total mass (kg)]) and percentage central BF (%CBF; [trunk fat mass (kg)]/[total mass (kg)]) were assessed through dual-energy X-ray absorptiometry. SETTING: Children were selected from schools in the greater Montreal, Sherbrooke and Quebec City metropolitan areas between 2005 and 2008, Quebec, Canada. SUBJECTS: A total of 546 children aged 8-10 years, including 244 girls and 302 boys. RESULTS: Regression analysis adjusting for age, sex, energy intake, physical activity and Tanner stage revealed that every 10-unit improvement in overall DQII score was associated with lower gain in CFMI (ß=-0·08; 95 % CI -0·17, -0·003) and %BF (ß=-0·55; 95 % CI -1·08, -0·02). Each unit improvement in dietary adequacy score was associated with lower gain in FMI (ß=-0·05; 95 % CI -0·08, -0·008), CFMI (ß=-0·03; 95 % CI -0·05, -0·007), %BF (ß=-0·15; 95 % CI -0·28, -0·03) and %CBF (ß=-0·09; 95 % CI -0·15, -0·02). CONCLUSIONS: Promotion of dietary quality and adequacy may reduce weight gain in childhood and prevent chronic diseases later in life.

Empowering women to breastfeed: Does the Baby Friendly Initiative make a difference?

The Baby-Friendly Hospital Initiative (BFI) is currently presented worldwide as the gold standard model of care for promoting and supporting breastfeeding. However, there is a lack of understanding about the ways in which health services, including the BFI, address the cultural change from a disembodied practice (formula feeding) to an embodied one (breastfeeding) in contexts where formula feeding is the norm. We used a qualitative case study methodology to compare the embodied experience of breastfeeding and the maternal experience of breastfeeding promotion and support services between mothers receiving care from institutions with low and high levels of BFI implementation in Québec, Canada. A total of 11 focus groups were conducted with mothers from six institutions-three with high and three with low levels of BFI implementation. We found the flexible approach to breastfeeding duration, characteristic of BFI services in our study, helped to avoid maternal guilt and shame; the shift to focusing on potential barriers and strategies for overcoming them empowered women to negotiate changes in infant feeding with others and self by addressing the embodied experience of a practice that may not feel natural at the beginning. Findings have implications for the concept of habitus and the construction of the breastfeeding body; we suggest that habitus can change if agents are provided with discursive tools to negotiate this embodied change. Implications for BFI services include the need to implement the 10 steps in a flexible, family-centred way that focuses on empowering women rather than simply reaching outcomes.

Canadian Consensus on Female Nutrition: Adolescence, Reproduction, Menopause, and Beyond.

OBJECTIVES: To provide health care professionals in Canada with the basic knowledge and tools to provide nutrition guidance to women through their lifecycle. OUTCOMES: Optimal nutrition through the female lifecycle was evaluated, with specific focus on adolescence, pre-conception, pregnancy, postpartum, menopause, and beyond. The guideline begins with an overview of guidance for all women, followed by chapters that examine the evidence and provide recommendations for the promotion of healthy nutrition and body weight at each life stage. Nutrients of special concern and other considerations unique to each life stage are discussed in each chapter. EVIDENCE: Published literature, governmental and health agency reports, clinical practice guidelines, grey literature, and textbook sources were used in supporting the recommendations made in this document. VALUES: The quality of evidence was rated using the criteria described in the report of the Canadian Task Force on Preventive Health Care. CHAPTER 2: GENERAL FEMALE NUTRITION: Summary Statements Recommendations CHAPTER 3: ADOLESCENCE NUTRITION: Summary Statements Recommendations CHAPTER 4: PRE-CONCEPTUAL NUTRITION: Summary Statement Recommendations CHAPTER 5: NUTRITION IN PREGNANCY: Summary Statements Recommendations CHAPTER 6: POSTPARTUM NUTRITION AND LACTATION: Summary Statements Recommendations CHAPTER 7: NUTRITION DURING MENOPAUSE AND BEYOND: Summary Statement Recommendations.

Consensus canadien sur la nutrition féminine : adolescence, reproduction, ménopause et au-delà.

OBJECTIFS: Doter les professionnels de la santé du Canada de connaissances et d'outils de base, afin qu'ils puissent prodiguer des conseils nutritionnels aux femmes tout au long de leur cycle de vie. RéSULTATS: L'alimentation optimale a fait l'objet d'une évaluation tout au long du cycle de vie de la femme. Elle a porté en particulier sur l'adolescence, la préconception, la grossesse, la période post-partum, la ménopause et au-delà. Le présent guide fournit d'abord des directives abrégées à l'intention de toutes les femmes. Elles sont suivies de chapitres proposant un examen des données probantes, ainsi que des recommandations sur la promotion d'une alimentation saine et d'un poids santé à chaque étape de la vie. Par ailleurs, tous les chapitres présentent une analyse de nutriments d'intérêt particulier, ainsi que d'autres aspects uniques à chaque étape de la vie. DONNéES PROBANTES: Des documents publiés, des rapports d'organismes gouvernementaux et de santé, des lignes directrices de pratique clinique, de la documentation parallèle et des extraits de manuels ont servi à étayer les recommandations formulées dans le présent document. VALEURS: L'évaluation de la qualité des données probantes repose sur les critères décrits dans le rapport du Groupe d'étude canadien sur les soins de santé préventifs. CHAPITRE 2 : CONSEILS GéNéRAUX SUR L'ALIMENTATION FéMININE: Déclarations Sommaires Recommandations CHAPITRE 3 : ALIMENTATION DE L'ADOLESCENTE: Déclarations Sommaires Recommandations CHAPITRE 4 : ALIMENTATION PRéCONCEPTIONNELLE: Déclarations Sommaires Recommandations CHAPITRE 5 : ALIMENTATION PENDANT LA GROSSESSE: Déclarations Sommaires Recommandations CHAPITRE 6 : ALIMENTATION ET LACTATION POST-PARTUM: Déclarations Sommaires Recommandations CHAPITRE 7 : ALIMENTATION PENDANT LA MéNOPAUSE ET AU-DELà: Déclarations Sommaires Recommandations.

Drastic increases in overweight and obesity from 1981 to 2010 and related risk factors: results from the Barbados Children's Health and Nutrition Study.

OBJECTIVE: To examine overweight and obesity (OWOB), changes in prevalence and potential risk factors in Barbadian children. DESIGN: A cross-section of students were weighed and measured. The WHO BMI-for-age growth references (BAZ), the International Obesity Task Force cut-offs and the US Centers for Disease Control and Prevention growth percentiles were used to determine OWOB prevalence. Harvard weight-for-height-for-age growth standards were used to estimate differences in OWOB prevalence from 1981 to 2010. Samples of parents and students were interviewed to describe correlates of OWOB. SETTING: Barbados. SUBJECTS: Public-school students (n 580) in class 3. RESULTS: Based on WHO BAZ, the overall prevalence of OWOB was 34·8 % (95 % CI 30·9, 38·7 %). A trend of higher OWOB prevalence was seen for girls across cut-offs, with significant sex differences noted using the International Obesity Task Force cut-offs. According to Harvard growth standards, OWOB has increased dramatically, from 8·52 % to 32·5 %. Children were more likely to be OWOB when annual household income was below BBD 9000 (OR=2·69; 95 % CI 1·21, 5·99). Eating dinner with the family every night was associated with a lower prevalence of OWOB (OR=0·56; 95 % CI 0·36, 0·87). CONCLUSIONS: The sharp increase of OWOB rates in Barbados warrants attention. Sex disparities in OWOB prevalence may emerge at a young age. Promoting family meals may be a feasible option for OWOB prevention. Understanding familial and sociodemographic factors influencing OWOB will be useful in planning successful intervention or prevention programmes in Barbados.

Protein intake protects against weight loss in healthy community-dwelling older adults.

Weight loss is prevalent in the elderly population, with deleterious health consequences, notably loss of lean body mass and subsequent functional decline. Protein intake below the current RDA [0.8 g/(kg · d)] is also common in older adults; however, the link between the 2 has received little attention. Our objective was to assess the relation between protein intake and incident 1-y weight loss ≥5% in community-dwelling older adults. We conducted a nested, prospective, case-control study in 1793 community-living elderly participants of the Quebec Longitudinal Study of Nutrition as a Determinant of Successful Aging (NuAge). We studied 211 incident cases of 1-y weight loss (≥5%) and 211 weight-stable controls (±2%) matched by sex and age category (70 ± 2, 75 ± 2, and 80 ± 2 y). Diet was measured by 3 nonconsecutive 24-h recalls. ORs (95% CIs) for the association between protein intake and weight loss were computed by using conditional logistic regression. After adjustment for body mass index, energy intake, appetite, smoking status, physical activity level, physical function, chronic diseases and medications, depressive symptoms, and serum albumin and ultrasensitive C-reactive protein, the ORs of weight loss in participants with low protein intakes [<0.8 g/(kg · d)] were 2.56 (95% CI: 1.01, 6.50) compared with participants with very high protein intakes [≥1.2 g/(kg · d)]. Corresponding numbers were 2.15 (95% CI: 1.02, 4.56) in participants with moderate protein intakes [0.8-<1.0 g/(kg · d)] and 1.33 (95% CI: 0.77, 2.28) in participants with high protein intakes [1.0-1.2 g/(kg · d)]. Our results suggest that protein intakes >1.0 g/(kg · d) are protective against weight loss in healthy older adults. These findings add epidemiologic evidence in support of higher optimal protein intakes than the current guidelines for healthy older adults.

Consumption of added sugars from liquid but not solid sources predicts impaired glucose homeostasis and insulin resistance among youth at risk of obesity.

Little is known about longitudinal associations between added sugar consumption (solid and liquid sources) and glucose-insulin homeostasis among youth. Caucasian children (8-10 y) with at least one obese biological parent were recruited in the QUébec Adipose and Lifestyle InvesTigation in Youth (QUALITY) cohort (n = 630) and followed-up 2 y later (n = 564). Added sugars were assessed by 3 24-h dietary recalls at baseline. Two-year changes were examined in multivariate linear regression models, adjusting for baseline level, age, sex, Tanner stage, energy intake, fat mass (dual-energy X-ray absorptiometry), and physical activity (7 d accelerometer). Added sugar intake in either liquid or solid sources was not related to changes in adiposity measures (fat mass, body mass index, or waist circumference). However, a higher consumption (10 g/d) of added sugars from liquid sources was associated with 0.04 mmol/L higher fasting glucose, 2.3 pmol/L higher fasting insulin, 0.1 unit higher homeostasis model assessment of insulin resistance (HOMA-IR), and 0.4 unit lower Matsuda-insulin sensitivity index (Matsuda-ISI) in all participants (P < 0.01). No associations were observed with consumption of added sugars from solid sources. Overweight/obese children at baseline had greater increases in adiposity indicators, fasting insulin, and HOMA-IR and decreases in Matsuda-ISI during those 2 y than normal-weight children. Consumption of added sugars from liquid or solid sources was not associated with changes in adiposity, but liquid added sugars were a risk factor for the development of impaired glucose homeostasis and insulin resistance over 2 y among youth at risk of obesity.

Dietary composition and its associations with insulin sensitivity and insulin secretion in youth.

The objectives of the present study were to examine the associations between macronutrient intake and insulin sensitivity (IS) and insulin secretion (ISct), taking into consideration moderate-to-vigorous physical activity (MVPA), fitness and sedentary behaviour. Caucasian youth (n 630) aged 8-10 years at recruitment, with at least one obese biological parent, were studied (QUebec Adipose and Lifestyle InvesTigation in Youth cohort). IS was measured using the homeostasis model assessment (HOMA) of insulin resistance and Matsuda IS index. ISct was measured using HOMA2%-ß, the ratio of the AUC of insulin:glucose over the first 30 min (AUC I/G(t= 30 min)) of the oral glucose tolerance test and AUC I/G(t= 120 min) over 2 h. Fitness was measured using VO2(peak), percentage of fat mass by dual-energy X-ray absorptiometry, and 7 d MVPA using accelerometry; screen time (ST) by average daily hours of self-reported television, video game or computer use. Dietary composition was measured using three non-consecutive dietary recalls. Non-parametric smoothing splines were used to model non-linear associations; all models were adjusted for age, sex, season, pubertal stage, MVPA, fitness, ST and adiposity. The percentage of total daily energy from dietary protein, fat, saturated fat and carbohydrate and the consumption of dietary vitamin D, sugar-sweetened beverages, fibre and portions of fruits and vegetables were taken into consideration. No dietary component was associated with any measure of IS after adjusting for MVPA, fitness, ST and adiposity. For every 1% increase in daily protein intake (%), AUC I/G(t= 30 min) decreased by 1·1% (P= 0·033). Otherwise, dietary composition was not associated with ISct. While long-term excess of energy intake has been shown to lead to overweight and obesity, dietary macronutrient composition is not independently correlated with IS or ISct in youth.

Unexpected effects of urban food activism on community and human wellbeing.

Participation in urban agriculture conducted through community gardens and allotments is known for its benefits to physical and mental health. Due to the recognition of these benefits, which include reduction of stress, depression and anxiety, such participation is increasingly being prescribed as a non-medical health intervention. Community gardens have the added advantage of immersion into a community, without the often-long waiting lists and level of commitment involved in allotment tenancies. What has not been explored is the demanding nature of the commitment required by volunteer coordinators, and ironically, the negative effects it can have on their wellbeing. In a study of food activism in Aberdeen, UK, we conducted 21 semi-structured interviews with participants from a range of bodies involved in the city's food growing projects. From the spectrum of food growers, we found that volunteer coordinators of community gardens experienced the greatest burdens on their time and wellbeing, with their demanding multi-functional roles leading to fatigue and feelings of over-commitment. Other problems encountered by community gardeners were over-reliance on grant funding and the disproportionate impacts of COVID closures on vulnerable groups. Policy interventions are required to reduce dependency on competitive grant funding and to support both coordinators and the long-term sustainability of community gardens.

Nucleotides sequestered at different subsite loci within DNA-binding pockets of two OB-fold single-stranded DNA-binding proteins are unstacked to different extents.

The gene 5 protein (g5p) encoded by the Ff strains of Escherichia coli bacteriophages is a dimeric single-stranded DNA-binding protein (SSB) that consists of two identical OB-fold (oligonucleotide/oligosaccharide-binding) motifs. Ultrafast time-resolved fluorescence measurements were carried out to investigate the effect of g5p binding on the conformation of 2-aminopurine (2AP) labels positioned between adenines or cytosines in the 16-nucleotide antiparallel tails of DNA hairpins. The measurements revealed significant changes in the conformational heterogeneity of the 2AP labels caused by g5p binding. The extent of the changes was dependent on sub-binding-site location, but generally resulted in base unstacking. When bound by g5p, the unstacked 2AP population increased from ∼ 22% to 59-67% in C-2AP-C segments and from 39% to 77% in an A-2AP-A segment. The OB-fold RPA70A domain of the human replication protein A also caused a significant amount of base unstacking at various locations within the DNA binding site as evidenced by steady-state fluorescence titration measurements using 2AP-labeled 5-mer DNAs. These solution studies support the concept that base unstacking at most of a protein's multiple sub-binding-site loci may be a feature that allows non-sequence specific OB-fold proteins to bind to single-stranded DNAs (ssDNAs) with minimal preference for particular sequences.

Household income, food insecurity and nutrition in Canadian youth.

OBJECTIVE: The contribution of nutrition to health inequalities is poorly understood, particularly with regard to children. The objective of this study was to examine the influence of income and the conjoint influence of low income and food insecurity on several dietary indicators in a representative sample of Canadian youth. METHODS: We used data from the Canadian Community Health Survey (CCHS) Cycle 2.2, a nationally representative population-based sample, to examine the diets of 8,938 youth aged 9-18 years. A single 24-hour recall was used to collect dietary information. Interviews were conducted in person, and anthropometric measurements were available for 71% of the sample. Estimates of variance were calculated using bootvar with weights specific to the CCHS. Generalized linear models were used to examine the associations between both low income and low-income food insecurity and anthropometric measures, food and nutrient intakes. RESULTS: Youth from low-income households had lower height percentiles than youth from higher-income households. Low-income girls (but not low-income boys) had a higher prevalence of BMI > or = 85th percentile than their higher-income counterparts. Among low-income food-insecure households, there was a higher prevalence of BMI > or = 85th percentile in boys than among the food-secure low-income boys. Calcium and vitamin D intakes were lower among boys and girls living in low-income households. Similarly, milk consumption was lower in low-income boys. Low-income food-insecure girls had lower milk intakes and higher intake of sweetened beverages. CONCLUSIONS: We found some evidence of nutritional deprivation among Canadian youth from disadvantaged households. Longer-term indicators of nutritional status such as lower height and greater weight among disadvantaged households were consistent with these findings.

Ultrafast fluorescence decay profiles reveal differential unstacking of 2-aminopurine from neighboring bases in single-stranded DNA-binding protein subsites.

Gene 5 protein (g5p) is a dimeric single-stranded DNA-binding protein encoded by Ff strains of Escherichia coli bacteriophages. The 2-fold rotationally symmetric binding sites of a g5p dimer each bind to four nucleotides, and the dimers bind with high cooperativity to saturate antiparallel single-stranded DNA (ssDNA) strands. Ultrafast time-resolved fluorescence spectroscopies were used to investigate the conformational heterogeneity and dynamics of fluorescent 2-aminopurine (2AP) labels sequestered by bound g5p. The 2AP labels were positioned within the noncomplementary antiparallel tail sequences of d(AC)(8) or d(AC)(9) of hairpin constructs so that each fluorescent label could probe a different subsite location within the DNA-binding site of g5p. Circular dichroism and isothermal calorimetric titrations yielded binding stoichiometries of approximately six dimers per oligomer hairpin when tails were of these lengths. Mobility shift assays demonstrated the formation of a single type of g5p-saturated complex. Femtosecond time-resolved fluorescence spectroscopy showed that the 2AP in the free (non-protein-bound) DNAs had similar heterogeneous distributions of conformations. However, there were significant changes, dominated by a large increase in the population of unstacked bases from ~22 to 59-68%, depending on their subsite locations, when the oligomers were saturated with g5p. Anisotropy data indicated that 2AP in the bound state was less flexible than in the free oligomer. A control oligomer was labeled with 2AP in the loop of the hairpin and showed no significant change in its base stacking upon g5p binding. A proposed model summarizes the data.

Probabilistic design of a near-surface CO2 leak detection system.

A methodology is developed for predicting the performance of near-surface CO(2) leak detection systems at geologic sequestration sites. The methodology integrates site characterization and modeling to predict the statistical properties of natural CO(2) fluxes, the transport of CO(2) from potential subsurface leakage points, and the detection of CO(2) surface fluxes by the monitoring network. The probability of leak detection is computed as the probability that the leakage signal is sufficient to increase the total flux beyond a statistically determined threshold. The methodology is illustrated for a highly idealized site monitored with CO(2) accumulation chamber measurements taken on a uniform grid. The TOUGH2 code is used to predict the spatial profile of surface CO(2) fluxes resulting from different leakage rates and different soil permeabilities. A response surface is fit to the TOUGH2 results to allow interpolation across a continuous range of values of permeability and leakage rate. The spatial distribution of leakage probability is assumed uniform in this application. Nonlinear, nonmonotonic relationships of network performance to soil permeability and network density are evident. In general, dense networks (with ∼10-20 m between monitors) are required to ensure a moderate to high probability of leak detection.

Short sleep duration is independently associated with overweight and obesity in Quebec children.

OBJECTIVE: To investigate the association of sleep duration with adiposity and to determine if caloric intake and physical activity mediate this relationship. METHODS: The Quebec Adiposity and Lifestyle Investigation in Youth (QUALITY) study is an ongoing longitudinal investigation of Caucasian children with at least one obese biological parent. Children (n = 550) with an average age of 9.6 years (SD = 0.9) who provided complete data at baseline were included in the cross-sectional analyses. Objective measures of adiposity (BMI Z-score, waist circumference, percent body fat measured by dual-energy X-ray absorptiometry), sleep duration and physical activity (accelerometer over 7 days), and diet (24-hour food recalls) were collected. Children were categorized into 4 groups according to sleep duration: < 10 hours, 10-10.9 hours, 11-11.9 hours, and > or = 12 hours of sleep per night. RESULTS: We observed a U-shaped relationship between sleep duration and all adiposity indices. None of energy intake, snacking, screen time or physical activity intensity differed significantly between sleep categories. After adjusting for age, sex, Tanner stage, highest educational level of the parents, total annual family income, and parental BMI, only short-duration sleepers (< 10 hours) had an increased odds of overweight/obesity (OR 2.08, 95% CI 1.16-3.67). Addition of total energy intake and physical activity to the model did not change the association substantially (OR 2.05, 95% CI 1.15-3.63). CONCLUSION: The present study provides evidence that short sleep duration is a risk factor for overweight and obesity in children, independent of potential covariates. These results further emphasize the need to add sleep duration to the determinants of obesity.