Associations between the home food environment and obesity-promoting eating behaviors in adolescence

Objective: This study examines relationships between multiple aspects of the home food environment and obesity-promoting characteristics of 12- to 13-year-old adolescents' diets, specifically frequency of consumption of high-energy fluids, sweet snacks, savory snacks, and take-out foods.

Research Methods: This was a cross-sectional study including 347 adolescents 12 to 13 years of age and their parents. Data were collected via self-completed surveys. The adolescents' diets were assessed using a Food Frequency Questionnaire derived from existing age-appropriate National Nutrition Survey data. An extensive range of domains within the home food environment were assessed. Bivariate linear regression analyses were run split by gender. Forced entry multiple linear regression analyses (adjusting for all variables significant in bivariate analyses as well as for maternal education) were also performed, stratified by the sex of the child.

Results: The influence of mothers, either as models for eating behaviors or as the providers of food, was pervasive. Mothers' intake of high-energy fluids (p = 0.003), sweet snacks (p = 0.010), savory snacks (p = 0.008), and take-out food (p = 0.007) was positively associated with boys' intake of all these foods. In addition, mothers' intake of high-energy fluids was positively associated with daughters' consumption of these drinks (p = 0.025). Furthermore, availability of unhealthy foods at home was positively associated with girls' sweet snack (p = 0.001), girls' savory snack (p < 0.001), boys' savory snack (p = 0.002), and, in the bivariate analyses, girls' high-energy fluid consumption (p = 0.002).

Discussion: This study of home food environment influences on adolescent diet highlights the pervasive influence of mothers in determining adolescents' obesity-promoting eating, providing direction for obesity prevention strategies and future research.

Health behaviors among individuals with schizophrenia and depression

This article presents findings from a study that evaluated the utility of Protection Motivation Theory to explain cardiovascular health behaviors among people with schizophrenia (n = 83) and depression (n = 70). Results indicated that the prevalence of overweight, cigarette smoking and a sedentary lifestyle were greater among people with a mental illness compared to individuals without a mental illness. Major predictors were high levels of fear of cardiovascular disease, lack of knowledge of correct dietary principles, lower self-efficacy, limited social support and psychiatric symptoms. Implications of these results are discussed in designing education and preventive health programs for individuals with schizophrenia and Mental Depressive Disorder (MDD).

Body dissatisfaction and body change behaviors in Chile : the role of sociocultural factors

With interest in body image and body change behaviors growing around the world, there has been surprisingly little research conducted in Latin America on these issues. In order to gain some understanding of them in this context, this study investigated body image and body change behaviors, and the sociocultural factors that may influence them, among 337 Chilean adolescents aged 12–18 years. Participants completed a questionnaire that assessed BMI, body dissatisfaction, strategies to lose weight and strategies to increase muscle bulk. In addition, perceived pressure from family, peers, and the media to change body shape was evaluated. Results were partially consistent with those reported in Western nations. Girls were found to report greater body dissatisfaction than boys, but no difference was found between males and females in perceived pressure from adults in the family or from older siblings/cousins to lose weight. However, girls experienced higher levels of perceived pressure to lose weight from the media than boys, and boys reported greater perceived pressure from peers to lose weight than girls, and more pressure than girls from all sources to increase muscle bulk. These findings are discussed in relation to research conducted in other contexts, and it is concluded that findings from other locations may not be applied universally.

Longitudinal examination of physical and relational aggression as precursors to later problem behaviors in adolescents

Research has addressed the consequences of being a victim of physical and relational aggression but less so the consequences of being an aggressor during adolescence. Consequently, relatively little is known about the extent to which aggression in early adolescence increases the risk of later aggression and other psychosocial problems. This study involves a representative sample of seventh- and ninth-grade students from Washington State ( N = 1,942). Students were surveyed on recruitment and then again 1 and 2 years later to learn about ongoing behavior problems, substance use, depression, and self-harm behaviors. Surveys also included measures of several hypothesized promotive factors: attachment to family, school commitment, and academic achievement. Findings suggest that being physically and/or relationally aggressive in grades 7 to 9 increases the risk of aggression and possibly other problem behaviors after accounting for age, gender, race, and a prior measure of each outcome. Independent promotive effects were observed in most analyses, although family attachment appeared a less robust predictor overall. Implications for prevention include acting on the behavior itself and enhancing promotive influences to lessen the risk of agression and other related problems.

Sociocultural influences on body dissatisfaction and body change behaviors among Malaysian adolescents

Little research on body dissatisfaction and body change behaviors, and the sociocultural influences on them, has been undertaken in non-Western contexts. The current study investigated these variables and the relationships between them among a sample of 529 Malaysian high school students (103 Malays, 344 Chinese and 82 Indians), who completed a set of measures in classroom settings. Chinese girls were more dissatisfied with their bodies than Chinese boys, but no gender difference was found for Malay and Indian participants. Girls were more likely to engage in behaviors to lose weight, and boys were more likely to engage in behaviors to increase muscle. The influence of sociocultural factors on body dissatisfaction and body change behaviors was limited and varied across both sex and ethnicity. Findings are discussed in relation to Western research, and it is concluded that cultural nuances need to be considered when investigating these phenomena.

Socioeconomic position and children's physical activity and sedentary behaviors : longitudinal findings from the CLAN study

Background: This study aimed to examine cross-sectional and longitudinal associations between socioeconomic position (SEP) and physical activity and sedentary behaviors amongst children and adolescents.

Methods: Maternal education was reported by parents of 184 5-6 year-old and 358 10-12 year-old children in 2001. In 2001 and 2004, physical activity was assessed by accelerometry. Older children self-reported and parents of younger children proxy-reported physical activity and television (TV) viewing behaviors. Linear regression was used to predict physical activity and sedentary behaviors, and changes in these behaviors, from maternal education.

Results: Among all children, accelerometer-determined and self/parent-reported moderate and vigorous physical activity declined over three years. Girls of higher SEP demonstrated greater decreases in TV viewing behaviours than those of low SEP. In general, no prospective associations were evident between SEP and objectively-assessed physical activity. A small number of prospective associations were noted between SEP and self-reported physical activity, but these were generally weak and inconsistent in direction.

Conclusions: This study did not find strong evidence that maternal education was cross-sectionally or longitudinally predictive of children’s physical activity or sedentary behaviors. Given the well-documented inverse relationship of SEP with physical activity levels in adult samples, findings suggest that such disparities may emerge after adolescence.

Glucose indices, health behaviors, and incidence of diabetes in Australia: the Australian diabetes, obesity and lifestyle study (AusDiab)

OBJECTIVE--We examined the associations of objectively measured sedentary time and physical activity with continuous indexes of metabolic risk in Australian adults without known diabetes.

RESEARCH DESIGN AND METHODS--An accelerometer was used to derive the percentage of monitoring time spent sedentary and in light-intensity and moderate-to-vigorous-intensity activity, as well as mean activity intensity, in 169 Australian Diabetes, Obesity and Lifestyle Study (AusDiab) participants (mean age 53.4 years). Associations with waist circumference, triglycerides, HDL cholesterol, resting blood pressure, fasting plasma glucose, and a clustered metabolic risk score were examined.

RESULTS--Independent of time spent in moderate-to-vigorous-intensity activity, there were significant associations of sedentary time, light-intensity time, and mean activity intensity with waist circumference and clustered metabolic risk. Independent of waist circumference, moderate-to-vigorous-intensity activity time was significantly beneficially associated with triglycerides.

CONCLUSIONS--These findings highlight the importance of decreasing sedentary time, as well as increasing time spent in physical activity, for metabolic health.

Studies with voltammetric microdisk electrodes

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Development and application of a microelectrode based scanning voltammetric detector

A large part of the work presented in this thesis describes the development and use of a novel electrochemical detector designed to allow the electrochemical characterisation of compounds in flowing solution by means of cyclic voltammetry. The detector was microprocessor controlled, which provides digital generation of the potential waveform and collection of data for subsequent analysis. Microdisk working electrodes are employed to permit both thermodynamic and kinetically controlled processes to be studied under steady-state conditions in flowing solutions without the distortion or hysteresis normally encountered with larger sized electrodes. The effect of electrode size, potential scan rate, and solution flow rate are studied extensively with the oxidation of ferrocene used as an example of a thermodynamically controlled process and a series of catecholamines as examples of a kinetically controlled process. The performance of the detector was best demonstrated when used as a HPLC post-column detector. The 3-dimensional chromatovoltammograms obtained allow on-line characterisation of each fraction as it elutes from the column. The rest of the work presented in this thesis involves the study of the oxidative degradation pathway of dithranol. The oxidative pathway was shown to involve a complex free radical mechanism, dependent on the presence of both oxygen and, in particular light. The pathway is further complicated by the fact that dithranol may exist in either a keto or enol form, the enol being most susceptible to oxidation. A likely mechanism is proposed from studies performed with cyclic voltammetry and controlled potential electrolysis, then defined by subsequent kinetic studies.

Investigation of nonisothermal crystallization behaviors of poly and silica nanocomposites using differential scanning calorimetry

Nonisothermal crystallization behaviors of PVA and poly (vinyl alcohol) and Silica (PVA/SiO2) nanocomposites prepared via a self-assembly monolayer (SAM) technique are investigated in this study. Differential scanning calorimetry (DSC) is used to measure the crystallization temperature and enthalpy of PVA and nanocomposites in nitrogen at various cooling rate. The results show that the degree of crystallinity of PVA and nanocomposites decreases when the SiO₂ content increases but increases with an increasing cooling rate. The peak crystallization temperature decreases with an increasing cooling rate.