Mediators of Weight Loss in a Family‐Based Intervention Presented over the Internet

Objective: To assess the process variables involved in a weight loss program for African‐American adolescent girls. Several process variables have been identified as affecting success in in vivo weight loss programs for adults and children, including program adherence, self‐efficacy, and social support. The current study sought to broaden the understanding of these process variables as they pertain to an intervention program that is presented using the Internet. It was hypothesized that variables such as program adherence, dietary self‐efficacy, psychological factors, and family environment factors would mediate the effect of the experimental condition on weight loss. Research Methods and Procedures: Participants were 57 adolescent African‐American girls who joined the program with one obese parent; family pairs were randomized to either a behavioral or control condition in an Internet‐based weight loss program. Outcome data (weight loss) are reported for the first 6 months of the intervention. Results: Results partially supported the hypotheses. For weight loss among adolescents, parent variables pertaining to life and family satisfaction were the strongest mediating variables. For parental weight loss, changes in dietary practices over the course of 6 months were the strongest mediators. Discussion: The identification of factors that enhance or impede weight loss for adolescents is an important step in improving weight loss programs for this group. The current findings suggest that family/parental variables exert a strong influence on weight loss efforts for adolescents and should be considered in developing future programs.     

Comparison of body composition methods in obese African-American women

Objective : To compare the accuracy of percentage body fat (%BF) estimates between bioelectrical impedance analysis (BIA) and DXA in obese African‐American women. Research Methods and Procedures : Fifty‐five obese African‐American women (mean age, 45 years; mean BMI, 38; mean %BF, 48%) were studied. BF was assessed by both BIA (RJL Systems BIA 101Q; RJL Systems, Clinton Township, MI) and DXA (Hologic QDR‐2000 Bone Densitometer; Hologic Inc., Bedford, MA). Generalized and ethnicity‐ and obese‐specific equations were used to calculate %BF from the BIA. Bland‐Altman analyses were used to compare the agreement between the BIA and the DXA, with the DXA serving as the criterion measure. Results : Two of the generalized equations provided consistent estimates across the weight range in comparison with the DXA estimates, whereas most of the other equations increasingly underestimated %BF as BF increased. One of the generalized and one of the ethnicity‐specific equations had mean differences that were not significantly different from the DXA value. Discussion : The findings show that the Lukaski equation provided the most precise and accurate estimates of %BF in comparison with the QDR 2000 and provide preliminary support for the use of this equation for obese African‐American women.     

Fine-root morphological trait variation in tropical forest ecosystems: an evidence synthesis

Plant Ecology - Key functions of fine roots are often related to their morphological traits, yet little is known about the patterns and controls on fine-root morphological traits in the tropical...     

An in situ approach to detect tree root ecology: linking ground‐penetrating radar imaging to isotope‐derived water acquisition zones

Tree root distribution and activity are determinants of belowground competition. However, studying root response to environmental and management conditions remains logistically challenging. Methodologically, nondestructive in situ tree root ecology analysis has lagged. In this study, we tested a nondestructive approach to determine tree coarse root architecture and function of a perennial tree crop, Theobroma cacao L., at two edaphically contrasting sites (sandstone and phyllite–granite derived soils) in Ghana, West Africa. We detected coarse root vertical distribution using ground‐penetrating radar and root activity via soil water acquisition using isotopic matching of δ¹⁸O plant and soil signatures. Coarse roots were detected to a depth of 50 cm, however, intraspecifc coarse root vertical distribution was modified by edaphic conditions. Soil δ¹⁸O isotopic signature declined with depth, providing conditions for plant–soil δ¹⁸O isotopic matching. This pattern held only under sandstone conditions where water acquisition zones were identifiably narrow in the 10–20 cm depth but broader under phyllite–granite conditions, presumably due to resource patchiness. Detected coarse root count by depth and measured fine root density were strongly correlated as were detected coarse root count and identified water acquisition zones, thus validating root detection capability of ground‐penetrating radar, but exclusively on sandstone soils. This approach was able to characterize trends between intraspecific root architecture and edaphic‐dependent resource availability, however, limited by site conditions. This study successfully demonstrates a new approach for in situ root studies that moves beyond invasive point sampling to nondestructive detection of root architecture and function. We discuss the transfer of such an approach to answer root ecology questions in various tree‐based landscapes.     

Evaluation of quenching and extraction procedures for performing metabolomics in <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis>

Introduction

Acidithiobacillus ferrooxidans has a central role in the microbial community metabolism that drives production of acid mine drainage (AMD), a major environmental concern. Metabolomic profiling can offer insight into how At. ferrooxidans contributes to these processes.

Objective

The unique biology of some organisms means that protocols for metabolomic profiling need to be species-specific. Current protocols have largely been optimized for neutrophilic model organisms and, presently, no protocol exists for studying acidophilic extremophiles such as At. ferrooxidans. An appropriate protocol was developed and applied to investigate At. ferrooxidans’ metabolomic capabilities in relation to the colonization of AMD sites.

Methods

We quantified the overall effectiveness of three quenching solutions in combination with three extraction solutions, quantifying the amount of metabolite leakage, number of metabolites extracted and degradation of C₁₃ labeled standards. We then used this method to quantify how the At. ferrooxidans metabolome differed between early and late stages in the logarithmic growth phase to investigate infer how the metabolism of the organism changes as it colonizes the AMD environment.

Results and discussion

An acidic methanol:water based quenching solution with ammonium formate salt used in conjunction with an isopropanol:methanol:water extraction solution produced the smallest amount of leakage, extracted the largest number of metabolites, and was most effective in recovering known standards. When this protocol was applied to the metabolomic fingerprinting of At. ferrooxidans in the beginning and end of its logarithmic growth phase, there was a clear separation in the metabolome at each growth point. Overall, 3% of the metabolome differed significantly.

     

Psychometric evaluation of the eating disorder examination-questionnaire for bariatric surgery candidates

Objective: Despite increasing use of the Eating Disorder Examination‐Questionnaire (EDE‐Q) in bariatric surgery patients, little is known about the utility and psychometric performance of this self‐report measure in this clinical group. The primary purpose of the current study was to evaluate the factor structure and construct validity of the EDE‐Q in a large series of bariatric surgery candidates. Methods and Procedures: Participants were 337 obese bariatric surgery candidates. Participants completed the EDE‐Q and a battery of behavioral and psychological measures. Results: Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) produced a 12‐item, 4‐factor structure of the EDE‐Q. The four factors, interpreted as Dietary Restraint, Eating Disturbance, Appearance Concerns, and Shape/Weight Overvaluation, were found to be internally consistent and converged with other relevant measures of psychopathology. Discussion: Factor analysis of the EDE‐Q in bariatric surgery candidates did not replicate the original subscales but revealed an alternative factor structure. Future research must further evaluate the psychometric properties, including the factor structure, of the EDE‐Q in this and other diverse populations and consider means of improving this measure's ability to best assess eating‐related pathology in bariatric surgery patients.     

Sex,Race/Ethnicity,Socioeconomic Status,and BMI in Relation to Self‐Perception of Overweight

Objective: To compare the self‐perception of overweight in the study population according to sex, race/ethnicity, and socioeconomic status and to compare the self‐perception of overweight among individuals classified as normal weight, overweight, and obese. Research Methods and Procedures: Data from 5440 adults who participated in the 1994 to 1996 Continuing Survey of Food Intakes by Individuals and the Diet and Health Knowledge Survey conducted by the U.S. Department of Agriculture were analyzed. Data for analysis included self‐perceived weight status, self‐reported weight and height, and demographic and socioeconomic data. Underweight individuals, defined as those with a body mass index <18.5 kg/m², were excluded from the analysis. Results: Self‐perception of overweight was more common in women compared with men and in whites compared with blacks or Hispanics. Both the correct and incorrect perception of overweight was more common in normal weight and overweight white women compared with black women. More overweight and obese white men correctly perceived their overweight status compared with black men. Multiple logistic regression showed that the odds ratio of perceived overweight was significantly higher in women, whites, and individuals with higher body mass index, higher income, and higher education. Discussion: Self‐perceived overweight varied by sex, race/ethnicity, and socioeconomic status. Erroneous perception of body weight may have important health and behavioral implications. In particular, a considerable proportion of overweight men may be at risk of obesity if they continue to perceive themselves as having normal weight.     

Accuracy of self-reported weight among bariatric surgery candidates: the influence of race and weight cycling

Objective: Research on the accuracy of self‐reported weight has indicated that the degree of misreporting (underestimating) weight is associated with increasing weight but is variable across patient groups. We examined the degree of discrepancy between actual and self‐reported BMI in severely obese bariatric surgery candidates, and whether the degree of accuracy varied by race and by eating‐related and psychological factors. Research Methods and Procedures: Participants were 179 obese female gastric bypass surgery candidates (31 black, 22 Hispanic, 126 white) who were asked to self‐report height and weight as part of a larger assessment battery. Actual height and weight were then measured and a discrepancy score was generated (actual BMI ? reported BMI). Results: In this group of severely obese patients, degree of misreporting was unrelated to BMI. The race groups did not differ in actual or self‐reported BMI but differed significantly in the degree of misestimation between self‐reported and actual BMI. Post hoc tests indicated that black women underestimated their BMI significantly more than white women; Hispanic women did not differ from the other race groups. No eating‐related or psychological variables assessed predicted percentage discrepancy; however, the accuracy in self‐reported weight was related to history of weight cycling. Discussion: Overall, obese bariatric surgery candidates were accurate in self‐report of weight, although the degree of accuracy differed by race and weight cycling history.