bluuebunny/crossref_metadata_2025 huggingface dataset:
Studying colloid transport in porous media using a geocentrifuge
Authors: Sharma Prabhakar , Flury Markus , Mattson Earl D.
Published: July 2008

Movement of colloids in the subsurface is a concern because mobile colloids may enhance the transport of contaminants. The excessive time required to conduct flow and transport experiments in porous media led to the use of centrifuges to evaluate subsurface transport processes. The objective of this study was to determine the suitability of centrifuges to study colloid transport in saturated porous media. We used a geocentrifuge to run colloid transport experiments under different centrifugal accelerations up to 20 g. Colloids of different densities were used: polystyrene (1.05 g/cm3), silica (2 g/cm3), and hematite (5.26 g/cm3). Deposition coefficients were obtained from the colloid breakthrough curves. We used filtration theory and a theory based on sedimentation‐diffusion to derive functional relationships between centrifugal acceleration and colloid and porous media properties, which allow us to predict the effect of acceleration on colloid transport. Comparison of experimental deposition coefficients with predictions based on filtration theory showed that filtration theory accurately predicted the behavior of polystyrene at higher accelerations but underpredicted colloid deposition for silica and hematite at accelerations higher than ∼10 g. The sedimentation‐diffusion theory allows us to determine whether a system is dominated by sedimentation or diffusion, or is in a transitional state. Theoretical predictions of colloid deposition in a porous medium agreed well with experiments, suggesting that the theory can be used to delineate when centrifugal acceleration will alter colloid transport in flow through column studies conducted in a centrifuge. Common subsurface colloids, such as iron oxides and aluminosilicates, can be affected at accelerations that are used in geocentrifuge transport studies (5 to 300 g). Even colloids with low specific densities, such as polystyrene, will be affected by centrifugal accelerations if their size is large.
A new bathymetric compilation highlighting extensive paleo–ice sheet drainage on the continental shelf, South Georgia, sub‐Antarctica
Authors: Graham Alastair G. C. , Fretwell Peter T. , Larter Robert D. , Hodgson Dominic A. , Wilson Christian K. , Tate Alex J. , Morris Peter
Published: July 2008

A grid derived from a new compilation of marine echo‐sounding data sets has allowed us to visualize and map the geomorphology of the entire continental shelf around South Georgia at an unprecedented level of detail. The grid is the first continuous bathymetric data set covering South Georgia to include multibeam swath bathymetry and represent them at a subkilometer resolution. Large and previously undescribed glacially eroded troughs, linked to South Georgia's modern‐day fjords, radiate from the island, marking the former pathways of large outlet glaciers and ice streams. A tectonic or geological influence is apparent for the major troughs, where glaciers have exploited structural weaknesses on the continental block. Bed forms lining the troughs give some first insights into glacial dynamics within the troughs, suggesting arteries of fast flowing ice occupied these topographic depressions in the past and operated over both bedrock and sedimentary substrates. On the outer shelf and within the troughs, large ridges and banks are also common, interpreted as terminal, lateral, and recessional moraines marking former positions of ice sheets on the shelf and their subsequent reorganization during deglaciation. A small trough mouth fan has developed at the mouth of at least one of the cross‐shelf troughs, demonstrating a focused sediment delivery to the margin. Slides and slide scars are also present on parts of the margin, showing that margin stability, perhaps also related to glaciation, has been an important factor in depositional processes on the continental slope. Implications of the new observations are that ice sheets have been more extensive on South Georgia than any previous studies have reported. Their age may date back to late Miocene times, and evolution of the shelf system has probably involved numerous late Cenozoic glacial episodes. However, relatively fresh seafloor geomorphology coupled with evidence from other maritime‐Antarctic islands (Heard Island and Kerguelen Island) indicating extensive glaciation at the Last Glacial Maximum raises the possibility that the extent of sub‐Antarctic glaciation for the Last Glacial period has, until now, been underestimated.
Characterization of contaminant phases in foraminifera carbonates by electron microprobe mapping
Authors: Pena L. D. , Cacho I. , Calvo E. , Pelejero C. , Eggins S. , Sadekov A.
Published: July 2008

The advent of new microanalytical techniques such as electron microprobe mapping (EMP) and laser ablation microsamplers coupled to mass spectrometers (LA‐ICP‐MS) provides a new array of possibilities to explore in great detail the trace elements distribution in foraminiferal carbonates. Here we apply these techniques to characterize diagenetic phases present in foraminiferal shells from Ocean Drilling Program Site 1240 in the Panama Basin, a region characterized by the presence of manganese‐rich minerals in the sediments. The combined application of these techniques allows us to characterize the elemental and spatial distribution on the surface and across the foraminiferal shells. Results illustrate the presence of at least two different Mn‐rich contaminant phases in the foraminiferal carbonates: Mn‐rich carbonates and ferromanganese oxides. Elemental maps also highlight the relevance of the foraminifera shell texture and porosity in the distribution and formation of these contaminant phases. In the case of Neogloboquadrina dutertrei, Mn phases form a continuous thin layer in the inner part of the chambers, whereas for Globigerinoides ruber, Mn phases have a rather patchy distribution and are usually found within the pores. Significant high magnesium concentrations are always associated with these Mn‐rich phases. These new findings support the need of removing these Mn‐rich contaminant phases in order to measure accurately the Mg/Ca ratios in the foraminifera shell and therefore obtain reliable Mg/Ca paleotemperature reconstructions.
Importance of a soil organic layer for Arctic climate: A sensitivity study with an Arctic RCM
Authors: Rinke Annette , Kuhry Peter , Dethloff Klaus
Published: July 2008

We incorporate a top soil organic layer in the land‐surface scheme of the regional climate model HIRHAM and discuss its implications for Arctic climate simulations. This inclusion modifies not only the ground thermal and hydrological regimes, but also dynamically feeds back into the atmosphere. The top organic layer reduces ground temperatures by 0.5°C to 8°C. Increased summer ground evaporation causes a significant drop in 2m air temperatures. Furthermore, the dynamical response due to heat flux changes affects the large‐scale atmospheric circulation. In winter, the mean sea level pressure is reduced over the Barents‐ and Kara Seas which is an improvement compared to observations.
Altitude resolved ice‐fraction in the uppermost tropical troposphere
Authors: Ekström M. , Eriksson P.
Published: July 2008

The exact nature of the processes responsible for the moistening of the upper tropical troposphere is still uncertain. Altitude resolved measurements of water vapor from Aura/Microwave Limb Sounder (MLS) and cloud ice from CloudSat are used to investigate the ratio of ice mass to total water. Horizontal and vertical ice‐fraction distributions in the pressure range 100–316 hPa over the tropical region are presented. They reveal that the ice‐fraction is generally low, less than 10% around 316 hPa in general and outside regions of deep convection in the altitude levels above. On the other hand, the ice‐fraction can be significant at higher altitudes in large regions above deep convection, reaching values of ∼90%. Below the tropical tropopause layer (TTL) ice and water vapor distributions have similar spatial patterns indicating that water in both phases is transported up to the upper troposphere by the same processes. Over regions of strong deep convection where ice is transported into the TTL, the dissimilar patterns of ice and water vapor could be interpreted as that the cloud ice gives a limited final moistening effect.
Increased winter precipitation over the North Pacific from 1984–1994 to 1995–2005 inferred from the Global Precipitation Climatology Project
Authors: Li Guohui , Wang Yuan , Lee Keun‐Hee , Diao Yiwei , Zhang Renyi
Published: July 2008

An analysis of the results from the Global Precipitation Climatology Project (GPCP) reveals a trend of increased wintertime precipitation over the North Pacific from 1984 to 2005. The precipitation over the North Pacific increases by about 1.5 mm/year in winter during the period of 1984 to 2005. Statistic analyses are performed to validate the observed precipitation trend, showing the f‐test and t‐test significances of greater than 99%. A cloud‐resolving weather research and forecast (CR‐WRF) model with a two‐moment bulk microphysical scheme is employed to consider the effects of an increasing Asian pollution outflow on wintertime precipitation over the North Pacific. The CR‐WRF simulations demonstrate more precipitation with elevated polluted continental aerosols than that with typical maritime aerosols, reproducing the observed precipitation trend. The results suggest that the increasing Asian pollution outflow represents one of the most plausible explanations for the increased precipitation trend observed in winter over the North Pacific, likely with important climate implications.
Impact of glycans on T‐cell tolerance to glycosylated self‐antigens
Authors: Purcell Anthony W , van Driel Ian R , Gleeson Paul A
Published: July 2008

There is now substantial evidence that antigen post‐translational modifications are recognized by T cells, and alterations in epitope modification has been linked to a number of autoimmune diseases. An estimated one third of the MHC ligands contain post‐translational modification of epitopes. A common post‐translational modification of proteins is glycosylation and it is predicted on theoretical grounds that ∼1–5% of MHC ligands may bear a glycan. From numerous studies over the past 15 years it is clear that glycans can influence T cell responses either by contribution to the structure of the epitope or by influencing the profile of peptide epitopes presented by APCs. The influence of glycans on antigen processing and T cell recognition has particular relevance to the induction of tolerance to self‐antigens. Here we discuss the potential impact of glycans on the profile of self‐epitopes presented by APCs and the consequence of changes in glycosylation to generate neo self‐epitopes resulting in the loss of tolerance and the development of autoimmune diseases. With the recent developments in profiling T cell epitopes, and with strategies for modulating glycosylation in vivo, it is now feasible to directly examine the global influence of glycans on self‐tolerance and autoimmunity.
Biological implications of glycosaminoglycan interactions with haemopoietic cytokines
Authors: Coombe Deirdre R
Published: July 2008

Heparan sulphate (HS) glycosaminoglycans (GAGs) are an integral part of the signalling complex of fibroblast derived growth factor (FGF) family members, HS being regarded as a coreceptor. FGFs are also retained in the tissues by binding to HS structures. Early studies on the contribution of the bone marrow stroma to haemopoiesis suggested that cytokines with a role in haemopoiesis were similarly retained in the stroma through interactions with HS. However, the functional outcomes of these cytokines binding HS were poorly understood. Here the GAG‐binding properties of cytokines of the four α‐helical bundle family and the biological consequences of such binding are reviewed. From this analysis it is apparent that although many of these cytokines do bind GAGs, GAG binding is not a consistent feature, nor is the site of GAG binding conserved among these cytokines. The biological outcome of GAG binding depends, in part, on the location of the GAG‐binding site on the cytokine. In some cases GAG binding appears to block signalling, whereas in others signalling is likely to be facilitated by binding. It is postulated that the interactions of these cytokines with their receptor complexes evolved independently of GAG binding, with GAG binding being an additional feature for a subset of this cytokine family. Nevertheless, because GAG binding localizes cytokines to sites within tissues, these interactions are likely to be critically important for the biology of these cytokines.
The Modulation of STAT5A/GR Complexes during Fat Cell Differentiation and in Mature Adipocytes
Authors: Baugh James E. , Floyd Z. Elizabeth , Stephens Jacqueline M.
Published: July 2008

Objective: Signal transducer and activator of transcription (STAT) 5A has been shown to interact with the glucocorticoid receptor (GR) in adipocytes. The aim of this study was to investigate the subcellular locations and modulation of STAT5A/GR complexes during adipogenesis and in mature adipocytes.

Research Methods and Procedures: Both 3T3‐L1 and 3T3‐F442A cells were studied by performing subcellular fractionations, immunoprecipitation, and Western blotting after various treatments.

Results: The formation of nuclear STAT5A/GR complexes was regulated in the cytosol and in the nucleus at distinct times during adipogenesis and in mature adipocytes. STAT5A, but not STAT5B, forms a complex with GR in adipocytes. The STAT5A associated with GR in the nucleus is tyrosine phosphorylated.

Discussion: The association of STAT5A with GR in the nucleus of adipocytes is modulated by the tyrosine phosphorylation of STAT5A. Both GR and STAT5A are known to have important roles in adipocyte function. Hence, our data suggest that the association of these two transcription factors may be important in the regulation of adipocyte gene expression.
Identification and Correlates of Weight Loss in Adolescents in a National Sample
Authors: Boutelle Kerri N. , Hannan Peter J. , Neumark‐Sztainer Dianne , Himes John H.
Published: July 2008

Objective: Little is known about behaviors associated with successful weight loss during adolescence. The first objective of the current study was to identify meaningful weight loss, weight maintenance, and weight gain in male and female adolescents. The second objective of this study was to apply these methods to U.S. adolescents from the National Health and Nutrition Survey 1999 to 2002 data and to identify factors associated with these weight change outcomes.

Research Methods and Procedures: The current analyses include 1726 (female, 836; male, 890) 16‐ to 18‐year‐old adolescents who completed the questionnaire components and interview for either the 1999–2000 or the 2001–2002 National Health and Nutrition Survey study. Dietary intake, physical activity, and dieting attitudes were compared across the weight loss (L), maintain (M), and gain (G) groups in the entire sample and in a subset of adolescents who are overweight and at‐risk‐for‐overweight (≥85th percentile).

Results: The tested method for identifying weight L, M, and G groups has both theoretical and statistical validity and, when applied to the sample, showed the expected direction of changes in weight. Results suggest that more overall physical activity, more vigorous exercise, and less sedentary activity are associated with being in the L group in both the full sample and the overweight and at‐risk‐for‐overweight sample. In addition, fewer teens in the L groups endorsed efforts at trying to lose weight, compared with the M and G groups.

Discussion: This study provides a method to determine successful adolescent weight loss for researchers and provides useful concrete information about successful weight loss for clinicians and others who work with adolescents.
Association of Eating Frequency with Body Fatness in Pre‐ and Postmenopausal Women
Authors: Yannakoulia Mary , Melistas Labros , Solomou Eleni , Yiannakouris Nikos
Published: July 2008

Objective: To examine associations between eating frequency (EF) and body fatness in pre‐ and postmenopausal women, after excluding potential low‐energy reporters.

Research Methods and Procedures: In this cross‐sectional study of 220 free‐living women, 64 pre‐ and 50 postmenopausal non‐low‐energy‐reporting women were further analyzed (age, 24 to 74 years; BMI, 18.5 to 38.6 kg/m2). Anthropometric and body composition measurements (DXA) were performed in all study participants. EF, energy, and macronutrient intake were assessed by 3‐day food record. Physical activity level and energy expenditure were assessed by self‐reported questionnaire.

Results: No association between EF and adiposity indices was detected in premenopausal women. In contrast, EF was positively correlated with percentage body fat in postmenopausal women (r = 0.30, p = 0.03). EF was positively correlated with total energy intake in both groups and with total energy expenditure in premenopausal women only (r = 0.34, p = 0.02). Multivariate analysis revealed that, in postmenopausal women, EF was a significant predictor of body fatness (standardized β = 0.41, p = 0.01).

Discussion: Frequent eating was not found to be related to adiposity in premenopausal women, but it was associated with increased body fat in postmenopausal women. Possible explanations could be that the frequent eating is not associated with a physically active lifestyle in postmenopausal women or that frequent eating predisposes women after menopause to a higher energy intake by increasing food stimuli and rendering it more difficult for them to control energy balance.
Comparison of Self‐reported and Measured BMI as Correlates of Disease Markers in U.S. Adults
Authors: McAdams Mara A. , Van Dam Rob M. , Hu Frank B.
Published: July 2008

Objective: The purpose of this study is to evaluate the validity of BMI based on self‐reported data by comparison with technician‐measured BMI and biomarkers of adiposity.

Research Methods and Procedures: We analyzed data from 10,639 National Health and Nutrition Education Study III participants ≥20 years of age to compare BMI calculated from self‐reported weight and height with BMI from technician‐measured values and body fatness estimated from bioelectrical impedance analysis in relation to systolic blood pressure, fasting blood levels of glucose, high‐density lipoprotein‐cholesterol, triglycerides, C‐reactive protein, and leptin.

Results: BMI based on self‐reported data (25.07 kg/m2) was lower than BMI based on technician measurements (25.52 kg/m2) because of underreporting weight (−0.56 kg; 95% confidence interval, −0.71, −0.41) and overreporting height (0.76 cm; 95% confidence interval, 0.64, 0.88). However, the correlations between self‐reported and measured BMI values were very high (0.95 for whites, 0.93 for blacks, and 0.90 for Mexican Americans). In terms of biomarkers, self‐reported and measured BMI values were equally correlated with fasting blood glucose (r = 0.43), high‐density lipoprotein‐cholesterol (r = −0.53), and systolic blood pressure (r = 0.54). Similar correlations were observed for both measures of BMI with plasma concentrations of triglycerides and leptin. These correlations did not differ appreciably by age, sex, ethnicity, or obesity status. Correlations for percentage body fat estimated through bioelectrical impedance analysis with these biomarkers were similar to those for BMI.

Discussion: The accuracy of self‐reported BMI is sufficient for epidemiological studies using disease biomarkers, although inappropriate for precise measures of obesity prevalence.
Increasing Trends in Waist Circumference and Abdominal Obesity among U.S. Adults
Authors: Li Chaoyang , Ford Earl S. , McGuire Lisa C. , Mokdad Ali H.
Published: July 2008

Objective: Some studies have shown that abdominal obesity may be a better predictor than overall obesity for disease risks and all‐cause mortality. This study sought to examine the recent trends in waist circumference (WC) among adults in the United States.

Research Methods and Procedures: Data from the National Health and Nutrition Examination Survey during 1988–1994, 1999–2000, 2001–2002, and 2003–2004 were analyzed to estimate the trends in the mean WC and the prevalence of abdominal obesity. Pooled t tests were used to test the differences in estimates between two time periods.

Results: Between the periods of 1988–1994 and 2003–2004, the age‐adjusted mean WC increased from 96.0 cm to 100.4 cm among men (p < 0.001) and from 89.0 cm to 94.0 cm among women (p < 0.001); the age‐adjusted prevalence of abdominal obesity increased from 29.5% to 42.4% among men (p < 0.001) and from 47.0% to 61.3% among women (p < 0.001). Between the periods of 1999–2000 and 2003–2004, a significant increase occurred in mean WC only among men (from 99.0 cm to 100.4 cm; p = 0.03) and in the prevalence of abdominal obesity among both men (from 37.0% to 42.2%; p = 0.03) and women (from 55.3% to 61.3%; p = 0.04). People with a BMI of 25 to 29 kg/m2 had a greater relative increase in abdominal obesity.

Discussion: The mean WC and the prevalence of abdominal obesity among U.S. adults have increased continuously during the past 15 years. Over one‐half of U.S. adults had abdominal obesity in the period of 2003–2004.
Nut Consumption and Weight Gain in a Mediterranean Cohort: The SUN Study
Authors: Bes‐Rastrollo Maira , Sabaté Joan , Gómez‐Gracia Enrique , Alonso Alvaro , Martínez J. Alfredo , Martínez‐González Miguel Angel
Published: July 2008

Objective: To assess the association, in a Mediterranean population, between nut consumption and risk of weight gain (at least 5 kg) or the risk of becoming overweight/obese.

Research Methods and Procedures: The Seguimiento Universidad de Navarra project is a prospective cohort of 8865 adult men and women who completed a follow‐up questionnaire after a median of 28 months. Dietary habits were assessed with a previously validated semiquantitative food‐frequency questionnaire.

Results: Nine hundred thirty‐seven participants reported a weight gain of ≥5 kg at follow‐up. After adjusting for age, sex, smoking, leisure time physical activity, and other known risk factors for obesity, participants who ate nuts two or more times per week had a significantly lower risk of weight gain (odds ratio: 0.69; 95% confidence interval: 0.53 to 0.90, p for trend = 0.006) than those who never or almost never ate nuts. Participants with little nut consumption (never/almost never) gained an average of 424 grams (95% confidence interval: 102 to 746) more than frequent nut eaters. Nut consumption was not significantly associated with incident overweight/obesity in the cohort.

Discussion: Frequent nut consumption was associated with a reduced risk of weight gain (5 kg or more). These results support the recommendation of nut consumption as an important component of a cardioprotective diet and also allay fears of possible weight gain.
Desaturation of Skeletal Muscle Structural and Depot Lipids in Obese Individuals during a Very‐Low‐Calorie Diet Intervention
Authors: Haugaard Steen B. , Vaag Allan , Høy Carl‐Erik , Madsbad Sten
Published: July 2008

Objective: This study investigated whether a very‐lowcalorie dietary intervention (VLCD) may influence composition of skeletal muscle cell membrane phospholipid and composition and concentration of intramyocellular triglyceride (IMTG) in obese subjects. The working hypothesis proposed that a VLCD would decrease saturated fatty acids (FAs) and increase long‐chain polyunsaturated FAs (LCPUFAs) in muscular structural lipids, as such changes have been associated with improved insulin sensitivity.

Research Methods and Procedures: Skeletal muscle biopsies (vastus lateralis) were obtained from 13 obese subjects (nine women) before and after 8 weeks on VLCD (∼600 to 800 kcal/d). FA composition in muscle cell membrane phospholipid and concentration and FA composition of IMTG were determined by gas‐liquid chromatography.

Results: Baseline BMI was 36.0 ± 3.4 kg/m2. Weight loss was 9.3 ± 1.1 kg (8.8 ± 1.1%; p < 0.0001); loss of adipose tissue was 5.9 ± 0.9 kg (p < 0.0001). Insulin resistance (by homeostasis model assessment) decreased (−44 ± 7%; p < 0.001). Muscle cell membrane phospholipid saturated FAs decreased (−3.2 ± 1.3%; p < 0.05), whereas monounsaturated FAs (4.3 ± 1.7%; p < 0.05), LCPUFAs (11 ± 6%; p < 0.05), and the ratio of LCPUFAs to saturated FAs (12 ± 5%; p < 0.05) increased. IMTG decreased, but not significantly (−5%). IMTG‐saturated FAs decreased (−3.3 ± 1.5%; p < 0.05), whereas LCPUFAn‐3 (29 ± 9%; p < 0.01), LCPUFAn‐6 (33 ± 9%; p < 0.01), and the ratio of LCPUFAs to saturated FAs (34 ± 8%; p < 0.001) increased. Plasma total cholesterol (−15 ± 6%; p < 0.05), low‐density lipoprotein‐cholesterol (−16 ± 5%; p < 0.01), high‐density lipoprotein‐cholesterol (−8 ± 2%; p < 0.01), and plasma triglyceride (−19 ± 12%; p = 0.10) all decreased during the VLCD.

Discussion: Desaturation of both muscle cell membrane phospholipid and IMTG was significant but modest during a VLCD in obese subjects. Further research must delineate whether such changes in skeletal muscle structural and depot lipid composition themselves are enough to promote the observed improvements in insulin action.
Awakening Cortisol Response in Lean, Obese, and Reduced Obese Individuals: Effect of Gender and Fat Distribution
Authors: Therrien Fanny , Drapeau Vicky , Lalonde Josée , Lupien Sonia J. , Beaulieu Serge , Tremblay Angelo , Richard Denis
Published: July 2008

Objective: Our goal was to assess the awakening cortisol response (ACR) in obese and reduced obese men and women.

Research Methods and Procedures: Fifty‐one men (16 lean, 19 abdominally obese, and 16 reduced obese) and 31 women (12 lean, 10 subcutaneously obese, and 9 reduced obese) were selected to participate to this study. Strict ranges of BMI and waist circumference were used to select the participants. Medical examination, psychological assessment, anthropometric measurements, and blood sampling were undergone at the laboratory. Cortisol response to awakening was determined with saliva cortisol sampling being taken immediately at the time of awakening and 30 minutes thereafter over 3 days within a period of 2 months.

Results: Men with visceral obesity exhibited an enhanced ACR, whereas this response tends to return to normal in a reduced obese state. In women, peripheral fat accumulation does not modify ACR, but weight loss increased the response.

Discussion: These results highlight gender effects on ACR of obese and reduced obese subjects, which could be accounted for by the different fat distribution profiles that characterize men and women. They also provide further support for the usefulness of ACR in assessing the hypothalamic‐pituitary‐adrenal axis activity status.
Bioelectrical Impedance vs. Four‐compartment Model to Assess Body Fat Change in Overweight Adults
Authors: Chouinard Laura E. , Schoeller Dale A. , Watras Abigail C. , Clark R. Randall , Close Rachel N. , Buchholz Andrea C.
Published: July 2008

Objective: The Tanita TBF‐305 body fat analyzer is marketed for home and clinical use and is based on the principles of leg‐to‐leg bioelectrical impedance analysis (BIA). Few studies have investigated the ability of leg‐to‐leg BIA to detect change in percentage fat mass (%FM) over time. Our objective was to determine the ability of leg‐to‐leg BIA vs. the four‐compartment (4C) model to detect small changes in %FM in overweight adults.

Research Methods and Procedures: Thirty‐eight overweight adults (BMI, 25.0 to 29.9 kg/m2; age, 18 to 44 years; 31 women) participated in a 6‐month, randomized, double‐blind, placebo‐controlled study of a nutritional supplement. Body composition was measured at 0 and 6 months using the Tanita TBF‐305 body fat analyzer [using equations derived by the manufacturer (%FMT‐Man) and by Jebb et al. (%FMT‐Jebb)] and the 4C model (%FM4C).

Results: Subjects in the experimental group lost 0.9%FM4C (p = 0.03), a loss that did not reach significance using leg‐to‐leg BIA (0.6%FMT‐Man, p = 0.151; 0.6%FMT‐Jebb, p = 0.144). We observed large standard deviations (SDs) in the mean difference in %FM between the 4C model and the TanitaManufacturer (2.5%) and TanitaJebb (2.2%). Ten subjects fell outside ±1 SD of the mean differences at 0 and 6 months; those individuals were younger and shorter than those within ±1 SD.

Discussion: Leg‐to‐leg BIA performed reasonably well in predicting decreases in %FM in this group of overweight adults but resulted in wide SDs vs. %FM4C in individuals. Cross‐sectional determinations of %FM of overweight individuals using leg‐to‐leg BIA should be interpreted with caution.
Chronological Approach of Diet‐induced Alterations in Muscle Mitochondrial Functions in Rats
Authors: Chanséaume Emilie , Tardy Anne‐Laure , Salles Jérôme , Giraudet Christophe , Rousset Paulette , Tissandier Antoine , Boirie Yves , Morio Béatrice
Published: July 2008

Objective: Mitochondrial dysfunction might predispose individuals to develop insulin resistance. Our objective was to determine whether mitochondrial dysfunction or insulin resistance was the primary event during high‐fat (HF) diet.

Research Methods and Procedures: Rats were fed an HF diet for 0, 3, 6, 9, 14, 20, or 40 days and compared with control. Soleus and tibialis muscle mitochondrial activity were assessed using permeabilized fiber technique. Insulin [area under the curve for insulin (AUCI)] and glucose [area under the curve for glucose (AUCG)] responses to intraperitoneal glucose tolerance test as well as fasting plasma non‐esterified fatty acids (NEFAs), triglyceride, and glycerol concentrations were determined.

Results: AUCI and AUCG were altered from Day 6 (p < 0.01 vs. Day 0). In soleus, oxidative phosphorylation (OXPHOS) activity was transiently enhanced by 26% after 14 days of HF diet (p < 0.05 vs. Day 0) conjointly with 62% increase in NEFA concentration (p < 0.05 vs. Day 0). This was associated with normalized AUCG at Day 14 and with a decline of plasma NEFA concentration together with stabilization of intra‐abdominal adiposity at Day 20. Prolongation of HF diet again caused an increase in plasma NEFA concentration, intra‐abdominal adiposity, AUCI, and AUCG. At Day 40, significant decrease in OXPHOS activity was observed in soleus.

Discussion: Mitochondria first adapt to overfeeding in oxidative muscle limiting excess fat deposition. This potentially contributes to maintain glucose homeostasis. Persistent overfeeding causes insulin resistance and results in a slow decline in oxidative muscle OXPHOS activity. This shows that the involvement of mitochondria in the predisposition to insulin resistance is mainly due to an inability to face prolonged excess fat delivery.
Short Sleep Duration is Associated with Reduced Leptin Levels and Increased Adiposity: Results from the Québec Family Study
Authors: Chaput Jean‐Philippe , Després Jean‐Pierre , Bouchard Claude , Tremblay Angelo
Published: July 2008

Objective: To explore cross‐sectional associations between short sleep duration and variations in body fat indices and leptin levels during adulthood in a sample of men and women involved in the Québec Family Study.

Research Methods and Procedures: Anthropometric measurements, plasma lipid‐lipoprotein profile, plasma leptin concentrations, and total sleep duration were determined in a sample of 323 men and 417 women ages 21 to 64 years.

Results: When compared with adults reporting 7 to 8 hours of sleep per day, the adjusted odds ratio for overweight/obesity was 1.38 (95% confidence interval, 0.89 to 2.10) for those with 9 to 10 hours of sleep and 1.69 (95% confidence interval, 1.15 to 2.39) for those with 5 to 6 hours of sleep, after adjustment for age, sex, and physical activity level. In each sex, we observed lower adiposity indices in the 7‐ to 8‐hour sleeping group than in the 5‐ to 6‐hour sleeping group. However, all of these significant differences disappeared after statistical adjustment for plasma leptin levels. Finally, the well‐documented regression of plasma leptin levels over body fat mass was used to predict leptin levels of short‐duration sleepers (5 and 6 hours of sleep), which were then compared with their measured values. As expected, the measured leptin values were significantly lower than predicted values.

Discussion: There may be optimal sleeping hours at which body weight regulation is facilitated. Indeed, short sleep duration predicts an increased risk of being overweight/obese in adults and is related to a reduced circulating leptin level relative to what is predicted by fat mass. Because sleep duration is a potentially modifiable risk factor, these findings might have important clinical implications for the prevention and treatment of obesity.
Associations between Multiple Measures of Parental Feeding and Children's Adiposity in United Kingdom Preschoolers
Authors: Carnell Susan , Wardle Jane
Published: July 2008

Objective: Research into the association between parental control over feeding and children's adiposity has produced inconclusive results. Some studies have found parental control to be associated with unhealthy food choices and disordered intake regulation, whereas others have found favorable or null associations between control and adiposity. This study hypothesized that variability in measures of parental feeding could contribute to these discrepancies. Scales from a range of existing parental feeding questionnaires were used together, in the same large sample of children, to examine associations with adiposity.

Research Methods and Procedures: Associations between scores on scales from three published parental feeding questionnaires [Child Feeding Questionnaire (CFQ); Preschooler Feeding Questionnaire (PFQ); and Parental Feeding Style Questionnaire (PFSQ)] and children's BMI z‐scores, calculated from measured heights and weights, were examined in a socioeconomically diverse sample of 439 parents and their 3‐ to 5‐year‐old children.

Results: Higher scores on CFQ Pressure to Eat and PFQ Pushing the Child to Eat More were significantly associated with lower BMI z‐score, while PFSQ Prompting to Eat, CFQ Restriction, PFSQ Instrumental Feeding, and PFSQ Emotional Feeding were unassociated with BMI z‐score.

Discussion: These results suggest that parents of leaner children are more likely to encourage their children to eat. Other feeding strategies seemed to have negligible relationships with children's BMI z‐scores at this stage. Longitudinal and genetically informed designs are needed to clarify the causal pathways between parental feeding and children's adiposity.
The Effects of a Low‐Carbohydrate Ketogenic Diet and a Low‐Fat Diet on Mood, Hunger, and Other Self‐Reported Symptoms
Authors: McClernon F. Joseph , Yancy William S. , Eberstein Jacqueline A. , Atkins Robert C. , Westman Eric C.
Published: July 2008

Objective: To investigate the effects of weight loss diets on mood, food cravings, and other self‐reported symptoms.

Research Methods and Procedures: Mood and other symptoms were evaluated by participant self‐report using the Atkins Health Indicator Test (AHIT) in individuals undergoing weight loss following either a low‐carbohydrate, ketogenic diet (LCKD) or a low‐fat diet (LFD). Participants were 119 overweight community volunteers randomized to an LCKD or an LFD. An additional 51 participants who had completed an earlier trial contributed data for the psychometric analyses but were not included in the prospective analyses. Self‐reported symptom levels on seven scales factor‐analytically derived from the AHIT (negative affect, fatigue, somatic symptoms, physical effects of hunger, insomnia, hunger, and stomach problems) were acquired during 12 visits.

Results: After adjusting for the change in BMI over the course of the trial, participants experienced significant improvements in most symptoms regardless of diet. Diet group × visit interactions were observed for negative affect [F(9,803) = 2.30, p = 0.015] and hunger [F(9,803) = 3.62, p < 0.0002]. Examination of means indicated that the LCKD group reported less negative affect and hunger, compared with the LFD group.

Discussion: Regardless of diet, participants experienced significant improvement in a broad range of symptoms. Symptoms of negative affect and hunger improved to a greater degree in patients following an LCKD compared with those following an LFD. Whether these symptom changes explain the greater short‐term weight loss generally experienced by LCKD followers deserves further research.
Controlled Study of Critical Parent and Family Factors in the Obesigenic Environment
Authors: Zeller Meg H. , Reiter‐Purtill Jennifer , Modi Avani C. , Gutzwiller Joeanne , Vannatta Kathryn , Davies W. Hobart
Published: July 2008

Objective: Critical gaps remain in our understanding of the obesigenic family environment. This study examines parent and family characteristics among obese youth presenting for treatment in a clinic setting.

Research Methods and Procedures: Families of 78 obese youth (BMI z‐score = 2.4; age, 8 to 16 years; 59% girls; 49% African‐American) were compared with 71 non‐overweight (BMI z‐score = −0.02) demographically matched comparisons. Parents completed measures assessing family demographics, psychological distress (Symptom Checklist 90‐Revised), and family functioning both broadly (Family Environment Scale: Conflicted, Support, Control) and at mealtimes (About Your Child's Eating‐Revised: Mealtime Challenges, Positive Mealtime Interaction). Height and weight were obtained from all participants.

Results: Compared with mothers and fathers of non‐overweight youth, parents of obese youth had significantly higher BMIs (p < 0.001). Mothers of obese youth reported significantly greater psychological distress (p < 0.01), higher family conflict (p < 0.05), and more mealtime challenges (p < 0.01). Less positive family mealtime interactions were reported by both mothers (p < 0.01) and fathers (p < 0.05) of obese youth. These group differences did not vary by child sex or race. Logistic regression analyses indicated that maternal distress and mealtime challenges discriminated between obese and non‐overweight youth after controlling for maternal BMI. Family conflict was explained, in part, by maternal distress.

Discussion: Obese youth who present for treatment in a clinic setting are characterized by psychosocial factors at the parent and family level that differ from non‐overweight youth. These data are critical because they identify factors that may be serving as barriers to a family's or youth's ability to implement healthy lifestyle behaviors but that are potentially modifiable.
Polyunsaturated Fatty Acid Pattern in Liver and Erythrocyte Phospholipids from Obese Patients
Authors: Elizondo Alejandra , Araya Julia , Rodrigo Ramón , Poniachik Jaime , Csendes Attila , Maluenda Fernando , Díaz Juan C. , Signorini Cinzia , Sgherri Cristiana , Comporti Mario , Videla Luis A.
Published: July 2008

Objective: Our aim was to study the fatty acid (FA) composition of liver phospholipids and its relation to that in erythrocyte membranes from patients with obese nonalcoholic fatty liver disease (NAFLD), as an indication of lipid metabolism alterations leading to steatosis.

Research Methods and Procedures: Eight control subjects who underwent antireflux surgery and 12 obese patients with NAFLD who underwent subtotal gastrectomy with a gastro‐jejunal anastomosis in Roux‐en‐Y were studied. The oxidative stress status of patients was assessed by serum F2‐isoprostanes levels (gas chromatography/negative ion chemical ionization tandem mass spectrometry). Analysis of FA composition of liver and erythrocyte phospholipids was carried out by gas‐liquid chromatography.

Results: Patients with NAFLD showed serum F2‐isoprostanes levels 84% higher than controls. Compared with controls, liver phospholipids from obese patients exhibited significantly 1) lower levels of 20:4n‐6, 22:5n‐3, 22:6n‐3 [docosahexaenoic acid (DHA)], total long‐chain polyunsaturated FA (LCPUFA), and total n‐3 LCPUFA, 2) higher 22:5n‐6 [docosapentaenoic acid (DPAn‐6)] levels and n‐6/n‐3 LCPUFA ratios, and 3) comparable levels of n‐6 LCPUFA. Levels of DHA and DPAn‐6 in liver were positively correlated with those in erythrocytes (r = 0.77 and r = 0.90, respectively; p < 0.0001), whereas DHA and DPAn‐6 showed a negative association in both tissues (r = −0.79, p < 0.0001 and r = −0.58, p < 0.01, respectively), associated with lower DHA/DPAn‐6 ratios.

Discussion: Obese patients with NAFLD showed marked alterations in the polyunsaturated fatty acid pattern of the liver. These changes are significantly correlated with those found in erythrocytes, thus suggesting that erythrocyte FA composition could be a reliable indicator of derangements in liver lipid metabolism in obese patients.
Internalization of Weight Bias: Implications for Binge Eating and Emotional Well‐being
Authors: Puhl Rebecca M. , Moss‐Racusin Corinne A. , Schwartz Marlene B.
Published: July 2008

Objective: This study examined the relationship between internalization of negative weight‐based stereotypes and indices of eating behaviors and emotional well‐being in a sample of overweight and obese women.

Research Method and Procedures: The sample was comprised of 1013 women who belonged to a national, non‐profit weight loss organization. Participants completed an on‐line battery of self‐report questionnaires measuring frequency of weight stigmatization and coping responses to deal with bias and symptoms of depression and self‐esteem, attitudes about weight and obesity, and binge eating behaviors. In addition, participants were asked to list the most common weight‐based stereotypes and whether they believed them to be true or false.

Results: Participants who believed that weight‐based stereotypes were true reported more frequent binge eating and refusal to diet in response to stigma experiences compared with those who reported stereotypes to be false. The degree to which participants believed stereotypes to be true or false was not related to types or amount of stigma experiences reported, self‐esteem, depression, or attitudes toward obese persons. In addition, engaging in weight loss strategies as a response to bias was not predicted by stereotype beliefs or by actual stigma experiences, regardless of the amount or types of stigma reported.

Discussion: These findings suggest that obese individuals who internalize negative weight‐based stereotypes may be particularly vulnerable to the negative impact of stigma on eating behaviors and also challenge the notion that stigma may motivate obese individuals to engage in efforts to lose weight. This study highlights a new area of research that warrants attention to better understand weight stigma and its potential consequences for health.
Lifecourse Socioeconomic Position and Weight Change among Blacks: The Pitt County Study
Authors: Bennett Gary G. , Wolin Kathleen Y. , James Sherman A.
Published: July 2008

Objective: The elevated prevalence of obesity among U.S. blacks has been attributed to low socioeconomic position (SEP), despite inconsistent empirical findings. It is unclear whether low SEP at various lifecourse stages differentially influences adulthood BMI and BMI change.

Research Methods and Procedures: Among 1167 black adults in the Pitt County Study, we examined independent cross‐sectional and longitudinal associations between SEP, measured in childhood and adulthood, and BMI and 13‐year BMI change. Low vs. high childhood SEP was measured by parental occupation and childhood household deprivation; low vs. high adulthood SEP was assessed by employment status, education, and occupation. Using childhood and adulthood SEP, four lifecourse SEP categories were created: low‐low, low‐high, high‐low, high‐high.

Results: We found no consistent associations between SEP and BMI or BMI change among men. Among women, we observed the expected inverse association between SEP and BMI at baseline. In multivariable‐adjusted analyses, socioeconomically advantaged women demonstrated larger 13‐year increases in BMI: skilled vs. unskilled parental occupation (6.1 vs. 4.8 kg/m2, p = 0.04); college‐educated vs. < high school (6.2 vs. 4.5 kg/m2, p = 0.04); white‐collar vs. blue‐collar job (5.8 vs. 4.8 kg/m2, p = 0.05); and high‐high vs. low‐low lifecourse SEP (6.5 vs. 4.6 kg/m2, p = 0.02).

Discussion: For women in this black cohort, lower SEP predicted earlier onset of obesity; however, low SEP was less predictive of BMI increases over time. Our findings demonstrate complex patterns of association between SEP and BMI change among black women.
Intra‐abdominal Fat Burden Discriminated In Vivo Using Proton Magnetic Resonance Spectroscopy
Authors: Walling Brent E. , Munasinghe Jeeva , Berrigan David , Bailey Michael Q. , Simpson R. Mark
Published: July 2008

Objective: To assess proton magnetic resonance spectroscopy (1H‐MRS) as a means to distinguish among mice with disparate intra‐abdominal body fat compositions, and to measure changes in intra‐abdominal fat burden during weight loss and regain.

Research Methods and Procedures: Intra‐abdominal fat burden was analyzed as a ratio of integrated areas under the curves of fat to water 1H‐MRS signals collected from a region of interest standardized across B6.V‐Lepob, C57BL/6, and A‐ZIP/F mice that exhibited various genotypically related body fat compositions, ranging from obese (B6.V‐Lepob) to minimal body fat (A‐ZIP/F). 1H‐MRS analysis of fat burden was compared with intra‐abdominal fat volume and with a single cross‐sectional intra‐abdominal fat area calculated from segmented magnetic resonance images. Similar measurements were made from obese B6.V‐Lepob mice before, during, and after they were induced to lose weight by leptin administration.

Results: Relative amounts of intra‐abdominal fat analyzed by 1H‐MRS differed significantly according to body composition and genotype of the three strains of mice (p < 0.05). Intra‐abdominal fat assessed by 1H‐MRS correlated with both intra‐abdominal fat volume (r = 0.88, p < 0.001) and body weight (r = 0.82, p < 0.001) among, but not within, all three genotypes. During weight loss and regain, there was a significant overall pattern of changes in intra‐abdominal fat quantity that occurred, which was reflected by 1H‐MRS (p = 0.006).

Discussion: Results support the use of localized 1H‐MRS for assessing differences in intra‐abdominal fat. Refinements in 1H‐MRS voxel region of interest size and location as well as instrument precision may result in improved correlations within certain body compositions.