bluuebunny/crossref_metadata_2025 huggingface dataset:
Qualitative and quantitative identification of copper oxides
Authors: Su Yea‐Yang , Shemenski Robert M.
Published: April 2008

The quality, thickness, and chemistry of oxides on metal surfaces play a vital role in a variety of applications. Some of these include adhesion of elastomers to metal surfaces, solar cell efficiency, sealing of electronic packaging, reduction of friction during wet drawing, and degree of biocompatibility of biomaterials. However, contradictory results and misidentification of oxide layers on metallic surfaces have caused ambiguity in interpretation of results leading to incorrect use in industrial application. This study will focus on the effect of experimental parameters such as electrolyte composition and concentration, current density, coating, time constant, surface roughness, and concentration of depolarizer on cathodic reduction of oxides on metallic wires to yield precise measurement and correct identification of oxide layers. Copyright © 2008 John Wiley & Sons, Ltd.
Molecular physiology and pathophysiology of lysosomal membrane transporters
Authors: Sagné C. , Gasnier B.
Published: April 2008

In contrast to lysosomal hydrolytic enzymes, the lysosomal membrane remains poorly characterized. In particular, although the genetic study of cystinosis and sialic acid storage disorders led to the identification of two lysosomal transporters for cystine and sialic acids, respectively, ten years ago, most transporters responsible for exporting lysosomal hydrolysis products to the cytosol are still unknown at the molecular level. However, two lines of investigation recently started to fill this gap in the knowledge of lysosomal biology. First, novel proteomic approaches are now able to provide a reliable inventory of lysosomal membrane proteins. On the other hand, a novel functional approach based on intracellular trafficking mechanisms allows direct transport measurement in whole cells by redirecting recombinant lysosomal transporters to the cell surface. After surveying the current state of knowledge in this field, the review focuses on the sialic acid transporter sialin and shows how recent functional data using the above whole‐cell approach shed new light on the pathogenesis of sialic acid storage disorders by revealing the existence of a residual transport activity associated with Salla disease.
A Hierarchical Bayesian Multidimensional Scaling Methodology for Accommodating Both Structural and Preference Heterogeneity
Authors: Park Joonwook , DeSarbo Wayne S. , Liechty John
Published: April 2008

Multidimensional scaling (MDS) models for the analysis of dominance data have been developed in the psychometric and classification literature to simultaneously capture subjects’ preference heterogeneity and the underlying dimensional structure for a set of designated stimuli in a parsimonious manner. There are two major types of latent utility models for such MDS models that have been traditionally used to represent subjects’ underlying utility functions: the scalar product or vector model and the ideal point or unfolding model. Although both models have been widely applied in various social science applications, implicit in the assumption of such MDS methods is that all subjects are homogeneous with respect to their underlying utility function; i.e., they all follow a vector model or an ideal point model. We extend these traditional approaches by presenting a Bayesian MDS model that combines both the vector model and the ideal point model in a generalized framework for modeling metric dominance data. This new Bayesian MDS methodology explicitly allows for mixtures of the vector and the ideal point models thereby accounting for both preference heterogeneity and structural heterogeneity. We use a marketing application regarding physicians’ prescription behavior of antidepressant drugs to estimate and compare a variety of spatial models.
Mesozoic and Cenozoic collisional structures of the southern Great Altai
Authors: Chikov B.M. , Zinoviev S.V. , Deyev E.V.
Published: April 2008

We suggest a model of the continental collisional framework of the southern Great Altai (Central Asia) produced by the convergence of the Tuva-Mongolia and Jonggaria terranes (microplates) during the latest Permian-Mesozoic and Cenozoic tectonic activity. The collisional structures in the region classified on the basis of their geometry and deformation style, dynamic metamorphism, and compositions of tectonites are of three main types: (i) mosaic terranes made up of large weakly deformed Paleozoic blocks separated by younger shear zones, (ii) collisional deformation systems involving post-Paleozoic structures, parallel faults oriented along collisional deformation systems, and relict lenses of Paleozoic orogenic complexes, and (iii) isolated zones of dynamic metamorphism composed mostly of collisional tectonites.
Array magnetotelluric soundings in the active seismic area of Northern Tien Shan
Authors: Rybin A.K. , Spichak V.V. , Batalev V.Yu. , Bataleva E.A. , Matyukov V.E.
Published: April 2008

High-density array MT soundings of the crust in the seismically active northern Tien Shan were performed using Phoenix MTU-5 stations in the Bishkek Geodynamic Polygon, at the junction of the Chu basin and the Kyrgyz Range. The MT transfer functions were determined to an accuracy of 1–2% (amplitude) and about 0.5–0.8 deg (phase) in most of 145 soundings. Preliminary analysis of the collected data aimed at estimating the geoelectrical dimensionality. The Bahr decomposition analysis indicated the presence of local 3D structures in the crust of the area superposed on the regional 2D structure.
Time-dependent stress change during failure of rocks
Authors: Belikov V.T. , Shestakov A.F.
Published: April 2008

The energy balance of a solid subject to fracture has been explored using heat and mass transfer equations with regard to the volumetric and superficial components. In the suggested model, brittle fracture of a cracked solid considered as a heterogeneous two-phase medium is described by an equation analogous to the Griffith’s criterion for propagation of a single crack. The derived equation is used, together with estimates of relative change in specific interface area, to study the respective change of free strain energy and pressure in rocks associated with failure.
Morphostructures and Cenozoic deposits on the right bank of the Kizir River (East Sayan)
Authors: Popova N.N. , Matsera A.V.
Published: April 2008

Study of morphostructures and Cenozoic deposits is important for reconstructing the history of the recent evolution of East Sayan and search for buried gold placers. Regional positive morphostructures of mountains with well-pronounced relief stages have been recognized in the Altai-Sayan area. The upper stage is referred to the Cretaceous-Paleogene; the middle one, to the Miocene-Pliocene; and the lower stage is dated at the Late Pliocene-Early Pleistocene. Negative morphostructures are recognized as a chain of intramontane basins and graben-like valleys of the Transbaikalian type. Troughs in the section bottom are filled with Cretaceous-Paleogene clayey crusts of weathering overlain by Neogene-Pleistocene deposits of complex composition. We studied the sections of Cenozoic deposits in the valleys of the Shinda and Verkhnyaya Chinzheba Rivers and made their palynological description.
Applying an aggregative dispersive dichotomy (ADD) model to parasitic infections in host populations
Authors: Pal P. , Abu-Madi M.A. , Lewis J.W.
Published: April 2008

An aggregative dispersive dichotomy (ADD) model is presented to describe the distribution of parasites in host populations. The ADD model is a mathematical construct which provides two complementary measures extracted from a reformulated negative binomial (NBD) and an inequality model, which combine to capture observed patterns of a parasitic infection. The dispersion element is modelled using the NBD with the threshold set at a parasite level above zero. By applying binomial dichotomy, the host community is divided into two sub-populations, one including hosts harbouring parasites up to the threshold and the other with parasites above the threshold level. Thekparameter, derived from the NBD, provides a cumulative probability. However,kis relatively insensitive to variations in the degree of aggregation, a known feature of the NBD model. The aggregation of parasites above the threshold in the host sub-population is evaluated by using an inequality model which is indexed by a scale-free parameter δ(δ ≥ 1) and provides an accurate measure of parasite aggregation. Applications of this model are made from field and simulated data in wood mouse populations infected with the trichostrongylid nematodeHeligmosomoides polygyrusfrom a woodland site in Surrey.
Anthelmintic efficacy ofAchillea millifoliumagainst gastrointestinal nematodes of sheep:in vitroandin vivostudies
Authors: Tariq K.A. , Chishti M.Z. , Ahmad F. , Shawl A.S.
Published: April 2008

Achillea millifoliumLinn., commonly called ‘Pehl-ghasa’, is used by farmers in traditional animal health care as a vermifuge. The objective of this study was to evaluate the anthelmintic efficacy of crude aqueous extracts and crude ethanolic extracts of entireA. millifoliumagainst the gastrointestinal nematodes of sheep. The worm motility inhibition assay was used forin vitrostudies and faecal egg count reduction assay was used forin vivostudies.In vitrostudies revealed significant anthelmintic effects of aqueous extracts and ethanolic extracts on liveHaemonchus contortusworms (P < 0.05) as evident from their paralysis and/or death at 8 h post exposure. Aqueous extracts ofA. millifoliumresulted in a mean worm motility inhibition of 94.44%, while ethanolic extracts resulted in mean worm motility inhibition of 88.88%. The mean mortality index of aqueous extracts was 0.95 while for ethanolic extracts it was 0.9. The lethal concentration 50 was 0.05 mg ml− 1for aqueous extracts and 0.11 mg ml− 1for ethanolic extracts. Thein vivoanthelmintic activity of aqueous and ethanolic extracts ofA. millifoliumdemonstrated a maximum (88.40%) nematode egg count reduction in sheep treated with aqueous extracts at 2 g kg− 1body weight on day 15 after treatment. Ethanolic extracts resulted in a maximum of 76.53% reduction in faecal egg counts on day 15 after treatment with 2 g kg− 1body weight. Thus, the aqueous extracts exhibited greater anthelmintic activity under bothin vitroandin vivoconditions, and could be due to the presence of water-soluble active principle/s inA. millifolium. It is concluded that the entire plant ofA. millifoliumpossesses significant anthelmintic activity and could be a potential alternative for treating cases of helminth infections in ruminants.
Dynamics of modulationally unstable ion-acoustic wavepackets in plasmas with negative ions
Authors: RUDERMAN MICHAEL S. , TALIPOVA TATYANA , PELINOVSKY EFIM
Published: April 2008

In this paper we study the propagation of nonlinear ion-acoustic waves in plasmas with negative ions. The Gardner equation governing these waves in plasmas with the negative ion concentration close to critical is derived. The weakly nonlinear theory of modulational instability based on the use of the nonlinear Schrödinger equation is discussed. The investigation of the nonlinear dynamics of modulationally unstable quasi-harmonic wavepackets is carried out by the numerical solution of the Gardner equation. The results are compared with the predictions of the weakly nonlinear theory.
Hospitalization rates for human metapneumovirus infection among 0- to 3-year-olds in Gipuzkoa (Basque Country), Spain
Authors: CILLA G. , OÑATE E. , PEREZ-YARZA E. G. , MONTES M. , VICENTE D. , PEREZ-TRALLERO E.
Published: April 2008

Numerous studies have been published on human metapneumovirus (HMPV) infection, but few have been population based. The main aim of this study was to estimate the incidence rate of hospitalization for community-acquired HMPV infection in infants and children aged <3 years. Between July 2004 and June 2007, 796 episodes (742 patients) of community-acquired acute respiratory infection were hospitalized. HMPV was detected in 90 episodes (11·3%). Fifty-nine episodes occurred in infants aged <1 year. The mean length of hospital stay was 6·2 days (range 2–31 days). Thirteen children required admission to the intensive care unit. Viral co-infections were detected in 46 episodes (51·1%). The incidence rate of hospitalization per 1000 inhabitants was 2·6 (95% CI 2·1–3·2), lower than that for respiratory syncytial virus, but higher than that observed for the influenza and parainfluenza viruses. HMPV is a major respiratory pathogen that leads to a high hospitalization rate.
Polarization in aurorae: A new dimension for space environments studies
Authors: Lilensten Jean , Moen Jøran , Barthélemy Mathieu , Thissen Roland , Simon Cyril , Lorentzen Dag A. , Dutuit Odile , Amblard Pierre Olivier , Sigernes Fred
Published: April 2008

The polarization of emission lines is a noteworthy observational parameter in astronomy. However, it has never been detected without ambiguity in planetary upper atmospheres. Theoretical considerations have suggested that the polarization of the thermospheric oxygen red line (630 nm) could exist in the polar cap region. We present here its first successful measurement at Svalbard in January 2007, during active geophysical conditions. We assign its origin and variability to complementary effects between permanent low‐energy electron precipitation and sporadic auroral events. Implications in physics, geophysics and planetary science are foreseen. In physics, it raises the question of the polarization of a forbidden transition by electron impact which is still unknown. In geophysics, it provides a new parameter to constrain the thermospheric models. In planetary science, it makes it possible to derive the local configuration of the magnetic fields. It therefore opens new perspectives for future space missions towards other planets
Light scattering by random shaped particles and consequences on measuring suspended sediments by laser diffraction
Authors: Agrawal Y. C. , Whitmire Amanda , Mikkelsen Ole A. , Pottsmith H. C.
Published: April 2008

We present new observational data on small‐angle light scattering properties of natural, random shaped particles, as contrasted with spherical particles. The interest in this “shape effect” on scattering arises from the need for a suitable kernel matrix for use in the laser diffraction method (LD) of particle sizing. LD is now used broadly for measuring size distribution of suspended marine particles. LD involves the measurement of small‐angle forward scattering at multiple angles. This data is inverted using the kernel matrix to produce size distribution. In the absence of a suitable matrix for random shaped particles, past practice has been to use a model based on Mie theory, applicable strictly only to homogeneous spheres. The present work replaces Mie theory with empirical data. The work was motivated in part by anomalous field observations of size distribution and settling velocity distributions reported in literature. We show that a kernel matrix for random shaped particles results in improved interpretation of field multiangle scattering observations. In particular, a rising edge at the fine particle end of the size spectrum is shown to be associated with shape effects.
Eddy transport of Western Mediterranean Intermediate Water to the Alboran Sea
Authors: Allen J. T. , Painter S. C. , Rixen M.
Published: April 2008

During the second cruise of the EU funded OMEGA project the towed undulating vehicle SeaSoar, was deployed to survey the upper 350 m of the water column in the eastern Alboran Sea and extreme western Algerian basin. With an effective along‐track resolution of 4 km, the data sets enabled a detailed description of the different upper ocean water types and the fronts that separate them. The Almeria Oran front forms at the eastern boundary of the Alboran Sea gyre system, in the upper 150–200 m of the water column, and separates waters of predominantly Atlantic origin from those formed in the Western Mediterranean Sea. Below these surface waters, but above the Levantine Intermediate Water, Western Mediterranean Intermediate Waters, believed to be formed to the north of the Balearic Sea, are normally observed in this region. However, to our knowledge, this is the first time a discrete eddy of Western Mediterranean Intermediate Water, a “weddy,” has been described in the extreme western Algerian basin. Repeated surveys of the region allowed us to observe the evolution of the eddy over a period of 40 d. A climatological analysis of historical data in the MEDAR/MEDATLAS database provides evidence for the repeatability of this observation and the significance of the estimated transport.
A corollary to the silicic acid leakage hypothesis
Authors: Matsumoto Katsumi , Sarmiento Jorge L.
Published: April 2008

The silicic acid leakage hypothesis (SALH) attempts to explain part of the large and regular atmospheric CO2 changes over the last glacial‐interglacial cycles. It calls for a reduction in the carbonate pump through a growth in diatoms at the expense of coccolithophorids in low‐latitude surface waters, driven by a “leakage” of high‐Si:N waters from the Southern Ocean. Recent studies that present low opal accumulation rates from the glacial eastern equatorial Pacific have challenged SALH. In a corollary to SALH, we argue that the key to SALH is the dominance of diatoms over coccolithophorids, and this does not depend on the magnitude of diatom production per se. In support of our claim, we show in a numerical model that atmospheric CO2 can be lowered with even a reduced absolute flux of silicic acid leakage, provided that Si:N in the leakage is elevated and that the excess Si can be used by diatoms to shift the floral composition in their favor.
Multiple scattering, radiative transfer, and weak localization in discrete random media: Unified microphysical approach
Authors: Mishchenko Michael I.
Published: April 2008

The radiative transfer theory has been extensively used in geophysics, remote sensing, and astrophysics for more than a century, but its physical basis had remained uncertain until quite recently. This ambiguous situation has finally changed, and the theory of radiative transfer in random particulate media has become a legitimate branch of Maxwell's electromagnetics. This tutorial review is intended to provide an accessible outline of recent basic developments. It discusses elastic electromagnetic scattering by random many‐particle groups and summarizes the unified microphysical approach to radiative transfer and the effect of weak localization of electromagnetic waves (otherwise known as coherent backscattering). It explains the exact meaning of such fundamental concepts as single and multiple scattering, demonstrates how the theories of radiative transfer and weak localization originate in the Maxwell equations, and exposes and corrects certain misconceptions of the traditional phenomenological approach to radiative transfer. It also discusses the challenges facing the theories of multiple scattering, radiative transfer, and weak localization in the context of geophysical applications.
Cardiovascular Vagosympathetic Activity in Rats with Ventromedial Hypothalamic Obesity
Authors: Valensi Paul , Doaré Liliane , Perret Gérard , Germack Renée , Pariès Jacques , Mesangeau Didier
Published: April 2008

Objective: Rats with ventromedial hypothalamic lesion (VMH) are massively obese with endogenous hyperinsulinemia, insulin resistance, low sympathetic activity, and high parasympathetic activity, which are likely to induce hypertension. The goal was to follow in this model the long‐term hemodynamic changes and to investigate the role of autonomic nervous system and insulin resistance in these changes.

Research Metho ds and Procedures: Heart rate and blood pressure were monitored for 12 weeks after operation using a telemetric system in VMH and sham rats. Plasma catecholamines and heart β‐adrenoceptors were measured. Glucose tolerance was studied after an intravenous glucose injection and insulin sensitivity during a euglycemic hyperinsulinemic clamp test.

Results: A marked bradycardia and only a mild increase in blood pressure occurred in VMH rats compared with sham animals. Response to autonomic‐acting drugs showed an increase in heart vagal tone and responsiveness to a β‐agonist drug. Plasma catecholamine levels were markedly increased, and the density and affinity of heart β‐adrenoceptors were similar in VMH, sham, and control rats. Muscle glucose use was reduced by 1 week after operation in VMH animals.

Discussion: These results show the following in this model of massively obese rats with sympathetic impairment: 1) adrenal medulla secretion is increased, probably as a result of hyperinsulinemia and increased vagal activity; 2) cardiac responsiveness to β‐agonist stimulation is increased; and 3) despite these changes and suspected resistance to the vasodilative effect of insulin, blood pressure does not increase. We conclude that high vagal activity may be protective against hypertension associated with obesity.
Fasting Plasma Insulin Modulates Lipid Levels and Particle Sizes in 2‐ to 3‐Year‐Old Children
Authors: Shea Steven , Aymong Eve , Zybert Patricia , Berglund Lars , Shamoon Harry , Deckelbaum Richard J. , Basch Charles E.
Published: April 2008

Objective: Obesity and hyperinsulinemia are associated with dyslipidemia in adults and older children, but little is known about these relationships in very young children. We examined the relation of fasting insulin to lipid levels and lipid particle size in young healthy children.

Research Methods and Procedures: Analyses were performed on data from 491 healthy 2‐ and 3‐year old Hispanic children enrolled in a dietary study conducted in New York City, 1992–1995. Obesity measures included BMI, ponderal index, skinfold thickness, and waist circumference. Low‐density lipoprotein (LDL)‐ and high‐density lipoprotein (HDL)‐cholesterol particle size were measured by nuclear magnetic resonance.

Results: Fasting insulin level was positively correlated with triglyceride levels (r = 0.24 for boys and r = 0.23 for girls; p < 0.001 for both) and inversely correlated with HDL‐cholesterol level in boys (r = −0.20; p < 0.01). Higher fasting insulin level was also correlated with smaller mean HDL particle size in both boys (r = −0.21; p < 0.001) and girls (r = −0.14; p < 0.05) and smaller mean LDL particle size in boys (r = −0.13; p < 0.05). The associations of fasting insulin level with triglyceride and HDL‐cholesterol levels and HDL and LDL particle size remained significant after multivariate regression adjustment for age, sex, and BMI or ponderal index.

Discussion: Fasting insulin level is associated with relative dyslipidemia in healthy 2‐ and 3‐year‐old Hispanic children.
Nosocomial Infections and Obesity in Surgical Patients
Authors: Cantürk Zeynep , Cantürk Nuh Zafer , Çetinarslan Berrin , Utkan Nihat Zafer , Tarkun Ilhan
Published: April 2008

Objective: There is an increased morbidity and mortality associated with surgery in the obese patient. This study was conducted to determine risk factors and compare the nosocomial infection rate in obese and nonobese surgical patients.

Research Methods and Procedures: A total of 395 surgical patients were evaluated. BMI was calculated for each patient. Various conventional risk factors for nosocomial infections were recorded. Biochemical parameters with plasma total cholesterol and high‐density lipoprotein‐cholesterol levels were measured. The diagnosis of infection was made according to the Centers for Disease Control and Prevention criteria. Univariate and two‐step multivariate logistic regression methods were used for determination of nosocomial infection risk factors.

Results: There were 117 nosocomial infections identified in 96 of 395 surgically operated patients. A significant increase in the total number of nosocomial infections was determined in obese patients compared with the normal‐weight patients (p < 0.05). High‐density lipoprotein‐cholesterol below the 10th percentile increased risk of surgical site infection.

Discussion: Our results suggest that obesity is an important risk factor for postoperative nosocomial infection.
Eating Behaviors and Indexes of Body Composition in Men and Women from the Québec Family Study
Authors: Provencher Véronique , Drapeau Vicky , Tremblay Angelo , Després Jean‐Pierre , Lemieux Simone
Published: April 2008

Objective: To put into relationship the dietary and anthropometric profile of men and women with their eating behaviors (cognitive dietary restraint, disinhibition, and susceptibility to hunger) and to assess whether gender and obesity status influence these associations.

Research Methods and Procedures: Anthropometric measurements (including visceral adipose tissue accumulation), dietary profile (3‐day food record), and eating behaviors (Three‐Factor Eating Questionnaire) were determined in a sample of 244 men and 352 women.

Results: Women had significantly higher cognitive dietary restraint and disinhibition scores than men (p < 0.0001). In both genders, scores for disinhibition and susceptibility to hunger, but not for cognitive dietary restraint, were higher in obese subjects than in overweight and nonobese subjects (p < 0.05). Positive correlations were observed between rigid restraint and most of the anthropometric variables studied (0.12 ≤ r ≤ 0.16). Moreover, in women, flexible restraint was negatively associated with body fat and waist circumference (r = −0.11). Cognitive dietary restraint and rigid restraint were positively related to BMI among nonobese women (0.19 ≤ r ≤ 0.20), whereas in obese men, cognitive dietary restraint and flexible restraint tended to be negatively correlated with BMI (−0.20 ≤ r ≤ −0.22; p = 0.10).

Discussion: Gender could mediate associations observed between eating behaviors and anthropometric profile. It was also found that disinhibition and susceptibility to hunger are positively associated with the level of obesity. On the other hand, cognitive dietary restraint is not consistently related to body weight and adiposity, whereas rigid and flexible restraint are oppositely associated to obesity status, which suggests that it is important to differentiate the subscales of cognitive dietary restraint. Finally, counseling aimed at coping with disinhibition and susceptibility to hunger could be of benefit for the long‐term treatment of obesity.
Genetic Contributions to Body Weight in Mice: Relationship of Exploratory Behavior to Weight
Authors: Zhang Shumin , Gershenfeld Howard K.
Published: April 2008

Objective: The A/J and C57BL/6J mouse strains differ markedly in their exploratory behavior and their weight gain on a high‐fat diet. We examined the genetic contributions of exploratory behavior to body weight and tested for shared, pleiotropic loci influencing energy homeostasis.

Research Methods and Procedures: Segregating (A×B6)F2 intercross (n = 514) and (B6AF1×A/J)N2 backcross (N = 223) populations were studied, phenotyping for weight and exploratory behaviors. Relationships among traits were analyzed by correlations. Weight traits were dissected with a genome‐wide scan.

Results: Modest correlations were found between exploratory behaviors and weight, explaining 2% to 14% of the variance. Quantitative trait loci (QTL) for body weight at 8 weeks (wgt8), 10 weeks (wgt10), and 2‐week weight gain (difference between weeks 8 and 10) on a 6% fat diet were mapped. Two QTL on chromosome 1 (peaks at 66 cM and 100 cM; Bw8q1) affected wgt8 [likelihood of the odds ratio (Lod), 3.0 and 4.4] and wgt10 (Lod, 2.2 and 3.4), respectively. In the backcross, a significant QTL on chromosome 4 (peak at 66 cM; Bw8q2) affected wgt 8 (Lod, 3.3) and wgt10 (Lod, 3.1). For 2‐week weight gain, suggestive QTL were mapped on chromosomes 4 and 6. The chromosome 6 QTL region overlaps a human 7q locus for obesity. A search for between‐strain sequence polymorphisms in the leptin and NPY genes was unrevealing.

Discussion: In mice, loci influencing exploratory activity play a modest role in body‐weight regulation. Some forms of obesity may emerge from loci regulating normal body weight.
Validity of Six Field and Laboratory Methods for Measurement of Body Composition in Boys
Authors: Parker Lisa , Reilly John J. , Slater Christine , Wells Jonathan C.K. , Pitsiladis Yannis
Published: April 2008

Objective: To determine the validity of the following six body composition methods against a reference method (three‐component model): air displacement plethysmography (BODPOD); estimation from body density using BODPOD; skinfold thickness using the Slaughter equations; bioelectrical impedance, both leg‐leg (TANITA) and hand—foot (Bodystat) approaches; and total body water.

Research Methods and Procedures: Forty‐two healthy white 10‐ to 14‐year‐old boys (mean age, 12.9 ± 1.0 years) were enrolled in this study. Measures of body fat percentage and body fat mass derived from the three‐component model were used as the reference method. Validity of all of the other methods was assessed by comparison against the reference by calculation of biases and limits of agreement.

Results: Mean body fatness measured using the reference method was 16.4 ± 11.6% and 8.7 ± 7.0 kg. Estimates of fatness from total body water had the narrowest limits of agreement relative to the reference (+0.9 ± 5.0% body fat; +0.5 ± 2.9 kg fat mass). For all other methods tested, we observed large biases and very wide limits of agreement.

Discussion: This study suggests that the validity of newer field and laboratory methods for estimation of body composition is poor in adolescent boys. For applications where high accuracy of estimation at the individual level is essential, only reference methods would be acceptable.
Predictors of Attrition in a Large Clinic‐Based Weight‐Loss Program
Authors: Honas Jeffery J. , Early James L. , Frederickson Doren D. , O'Brien Megan S.
Published: April 2008

Objective: Identifying client factors that predict dropout is critical for the development of effective weight‐loss programs. Although demographic predictors are studied, there are few consistent findings. The purpose of this study was to identify predictors of dropout in a large clinic‐based weight‐loss program using readily attainable demographic variables.

Research Methods and Procedures: All 866 weight‐loss patients in a clinic‐based weight‐loss program enrolled during 1998 to 1999 were followed. Attrition and retention rates were measured at 8 and 16 weeks. Six variables (sex, race, marital status, age, BMI, and treatment protocol) were evaluated using bivariate and multivariable statistics for relative association with dropout.

Results: The overall attrition rate for the 16‐week program was 31%. The retention rate was 69%. Significant risk for dropout, measured as bivariate relative risk (95% confidence interval), was found among patients who were: females, 1.32 (1.01 to 1.73); divorced, 1.54 (1.13 to 2.09); African Americans, 1.68 (1.26 to 2.23); age < 40, 1.66 (1.27 to 2.18); and ages 40 to 50, 1.33 (1.01 to 1.76). There were no significant differences in retention rates by BMI group or program protocol. After logistic regression analysis to control for all variables, young age < 50 years had the only significant association with dropout [odds ratio = 1.39 (1.02 to 1.90)].

Discussion: Multivariable modeling was helpful for prioritizing risk factors for program dropout. These findings have important implications for improving weight‐loss program effectiveness and reducing attrition. By knowing the groups at risk for dropout, we can improve or target program treatments to these populations.
Association of African Genetic Admixture with Resting Metabolic Rate and Obesity Among Women
Authors: Fernández José R. , Shriver Mark D. , Beasley T. Mark , Rafla‐Demetrious Nashwa , Parra Esteban , Albu Jeanine , Nicklas Barbara , Ryan Alice S. , McKeigue Paul M. , Hoggart Clive L. , Weinsier Roland L. , Allison David B.
Published: April 2008

Objective: To investigate the role of genetic admixture in explaining phenotypic variation in obesity‐related traits in a sample of African‐American women (n = 145) and to determine significant associations between obesity traits and admixture genetic markers.

Research Methods and Procedures: Associations between genetic admixture and BMI, resting metabolic rate, fat mass, fat‐free mass, and bone mineral density were tested using linear regression considering the estimation of admixture by 1) a maximum‐likelihood approach (MLA) and 2) a Bayesian analysis.

Results: Both the conservative MLA and the Bayesian approach support an association between African genetic admixture and BMI. Evidence for the associations of African genetic admixture with fat mass and fat‐free mass was supported by the Bayesian analysis; the MLA supported an association with bone mineral density. When the individual ancestry informative markers that were used to estimate admixture were tested for associations with BMI, significant associations were identified in chromosomes 1, 11, and 12.

Discussion: These results provide evidence supporting the application of admixture mapping methods to the identification of genes that result in higher levels of obesity among African‐American women. Further research is needed to replicate and further explore these findings.
Serum Ghrelin Levels in Response to Glucose Load in Obese Subjects Post‐Gastric Bypass Surgery
Authors: Tritos Nicholas A. , Mun Edward , Bertkau Anne , Grayson Rebecca , Maratos‐Flier Eleftheria , Goldfine Allison
Published: April 2008

Objective: We sought to elucidate further the mechanisms leading to weight loss after gastric bypass (GBP) surgery in morbidly obese individuals. Ghrelin is a gastroenteric appetite‐stimulating peptide hormone, fasting levels of which decrease with increasing adiposity and increase with diet‐induced weight loss. In addition, ghrelin levels rapidly decline postprandially.

Research Methods and Procedures: We measured serum ghrelin responses to a 75‐g oral glucose tolerance test (OGTT) in 6 subjects who had undergone GBP surgery 1.5 ± 0.7 years before testing and compared these responses with 6 obese subjects about to undergo GBP surgery, 6 obese nonsurgical subjects (matched for BMI to the post‐GBP surgical group), and 5 lean subjects.

Results: Despite weight loss induced by the GBP surgery, fasting serum ghrelin levels were significantly lower in the post‐GBP surgery group than in the lean subject (by 57%) or pre‐GBP surgery (by 45%) group. Serum ghrelin levels during the OGTT were significantly lower in postoperative than in lean, obese pre‐GBP surgical, or obese nonsurgical subjects. The magnitude of the decline in serum ghrelin levels between 0 and 120 minutes post‐OGTT was significantly smaller in postoperative (by 62%), obese pre‐GBP surgical (by 80%), or obese nonsurgical (by 69%) subjects in comparison with lean subjects.

Discussion: Serum ghrelin levels in response to OGTT are lower in subjects post‐GBP surgery than in either lean or obese subjects. Tonically low serum ghrelin levels may be involved in the mechanisms inducing sustained weight loss after GBP surgery.
Expression of the mRNAs Coding for the Glucocorticoid Receptor Isoforms in Obesity
Authors: Boullu‐Ciocca Sandrine , Paulmyer‐Lacroix Odile , Fina Frédéric , Ouafik L'Houcine , Alessi Marie‐Christine , Oliver Charles , Grino Michel
Published: April 2008

Objective: Glucocorticoids may be a pathophysiological mediator for the development of visceral obesity. In obese patients, adipose tissue reactivation of cortisone to cortisol is enhanced. In addition, changes in glucocorticoid receptor (GR) could also be important, either at the central nervous system level, by modulating the negative glucocorticoid feedback, or at a peripheral level, by regulating adipose tissue activity.

Research Methods and Procedures: Using quantitative reverse transcriptase‐polymerase chain reaction, we studied the expression of the GR mRNA isoforms (active, GRα inactive, GRβ) in circulating mononuclear leukocytes (in which GR shares the same regulation with central nervous system GR) obtained from normal weight women (n = 65) and patients with gluteofemoral (n = 26) or visceral (n = 39) obesity. Using in situ hybridization, we measured GRα mRNA levels in adipose tissue from control (n = 10) or obese (n = 15) patients.

Results: The mean α/β ratio was decreased in mononuclear leukocytes from obese patients (2.6, 9.2, and 32.1, respectively). GRα mRNA levels were significantly decreased in subcutaneous abdominal adipose tissue obtained from obese patients compared with nonobese ones, suggesting the existence of a downregulation of GR gene expression. This phenomenon was not found in visceral adipose tissue.

Discussion: This suggests that, in obese patients, the relative insensitivity to the negative glucocorticoid feedback is, at least in part, subsequent to a dysregulation of the GRα/GRβ ratio and that visceral, but not subcutaneous, adipose tissue retains a full capacity to respond to increased local generation of cortisol.
Weight Loss Reduces Tissue Factor in Morbidly Obese Patients
Authors: Kopp Christoph W. , Kopp Hans‐Peter , Steiner Sabine , Kriwanek Stephan , Krzyzanowska Katarzyna , Bartok Andrea , Roka Rudolf , Minar Erich , Schernthaner Guntram
Published: April 2008

Objective: To investigate the tissue factor (TF) pathway in clinical obesity and associated metabolic syndrome.

Research Methods and Procedures: Thirty‐seven morbidly obese patients (4 men; BMI, 48 ± 7 kg/m2; range, 42 to 53 kg/m2), undergoing elective gastroplasty for the induction of weight loss, were examined for hemostatic, metabolic, and inflammatory parameters at baseline and 14 ± 5 months postoperatively.

Results: Weight loss significantly reduced circulating plasma TF (314 ± 181 vs. 235 ± 113 pg/mL, p = 0.04), coagulation factor VII (130 ± 22% vs. 113 ± 19%, p = 0.023), and prothrombin fragment F1.2 (2.4 ± 3.4 vs. 1.14 ± 1.1 nM, p = 0.04) and normalized glucose metabolism in 50% of obese patients preoperatively classified as diabetic or of impaired glucose tolerance. The postoperative decrease in plasma TF correlated with the decrease of F1.2 (r = 0.56; p = 0.005), a marker of in vivo thrombin formation. In subgroup analysis stratified by preoperative glucose tolerance, baseline circulating TF (402.6 ± 141.6 vs. 176.2 ± 58.2, p < 0.001) and TF decrease after gastroplasty (ΔTF: 164.7 ± 51.4 vs. −81 ± 31 pg/mL, p = 0.02) were significantly higher in obese patients with impaired glucose tolerance than in patients with normal glucose tolerance.

Discussion: Procoagulant TF is significantly reduced with weight loss and may contribute to a reduction in cardiovascular risk associated with obesity.
Characteristics of Women with Persistent Thinness
Authors: Slof Rita , Mazzeo Suzanne , Bulik Cynthia M.
Published: April 2008

Objective: Western society has become increasingly obesogenic. Despite this trend, some individuals maintain low weights throughout their lives. Little is known about the characteristics of persistently thin individuals. This study examined demographic, health, and psychiatric characteristics of women who reported having been persistently thin throughout childhood, adolescence, and adulthood.

Research Methods and Procedures: Participants were 1022 female members of a population‐based twin registry. Participants completed a mail survey that included questions regarding demographics, body size in childhood, adolescence, and adulthood, health behaviors and satisfaction, disordered eating, perfectionism, and personality. In previous interview waves, participants completed diagnostic interviews assessing psychiatric and substance use disorders.

Results: Persistent thinness was associated with a significantly later age at menarche, lower rates of dieting and binge eating, greater health satisfaction, higher self‐esteem, and lower perfectionism and body dissatisfaction.

Discussion: Persistent thinness appears to be associated with greater well‐being in the present and a later age of menarche in the past. Whether later menarche is causally related to thinness or whether later menarche, persistent thinness, and enhanced well‐being all result from a third unmeasured variable such as high sports participation is yet to be resolved.
Variations in Body Composition and Plasma Lipids in Response to a High‐Carbohydrate Diet
Authors: Archer W. Roodly , Lamarche Benoît , Dériaz Olivier , Landry Nancy , Corneau Louise , Després Jean‐Pierre , Bergeron Jean , Couture Patrick , Bergeron Nathalie
Published: April 2008

Objective: To examine the extent to which variations in body composition modulate changes in the lipid profile in response to the ad libitum consumption of a diet rich in carbohydrates (CHOs) (high‐CHO diet: 58% of energy as CHOs) or high in fat and in monounsaturated fatty acids (MUFAs) (high‐MUFA diet: 40% of energy as fat, 23% as MUFAs).

Research Methods and Procedures: Sixty‐three men were randomly assigned to one of the two diets that they consumed for 6 to 7 weeks. Body composition and fasting plasma lipid levels were measured at the beginning and the end of the dietary intervention.

Results: The high‐CHO and high‐MUFA diets induced significant and comparable reductions in body weight and waist circumference. These changes were accompanied by significant and comparable (p < 0.01) reductions in total plasma cholesterol and low‐density lipoprotein cholesterol levels. However, the high‐MUFA diet had more beneficial effects on plasma triglyceride concentrations (p < 0.01) and on plasma high‐density lipoprotein cholesterol levels (p = 0.02) compared with the high‐CHO diet. Diet‐induced changes in waist circumference were significantly associated with changes in low‐density lipoprotein cholesterol levels in the high‐CHO group (r = 0.39, p = 0.03) but not in the high‐MUFA group (r = 0.16, p = 0.38).

Discussion: Improvements in plasma lipids induced by the ad libitum consumption of a high‐CHO diet seem to be partly mediated by changes in body weight, whereas lipid changes induced by the high‐MUFA diet seem to be independent of changes in body weight.
Association of Polymorphisms in the Interleukin 6 Receptor Complex with Obesity and Hyperandrogenism
Authors: Escobar‐Morreale Héctor F. , Calvo Rosa M. , Villuendas Gemma , Sancho José , San Millán José L.
Published: April 2008

Objective: Interleukin‐6 (IL‐6), is an inflammatory cytokine that may influence the pathogenesis of obesity and hyperandrogenism. IL‐6 exerts its actions through a heterodimeric receptor consisting of two membrane‐bound glycoproteins: an 80‐kDa IL‐6 binding unit (IL6R‐α) and a 130‐kDa IL‐6 signal transducer (gp130). Genetic variability at these loci might contribute to explain the development of obesity and hyperandrogenism.

Research Methods and Procedures: We have evaluated the possible association of several polymorphisms in the IL6R‐α and gp130 genes with obesity and/or hyperandrogenism in a case‐control study involving 143 hyperandrogenic patients and 45 healthy women from Spain.

Results: A microsatellite CA‐repeat polymorphism in the IL6R‐α locus was associated with obesity. The frequency of the common 149‐bp allele was markedly increased in obese women compared with controls when considering patients and controls as a whole (0.41 vs. 0.29, χ2 = 17.085, p < 0.050). On the other hand, the uncommon Arg148 allele of the Gly148Arg polymorphism in the gp130 gene was more frequent in controls compared with hyperandrogenic patients (0.17 vs. 0.08, χ2 = 5.605, p = 0.026). Controls carrying Arg148 alleles had lower 11‐deoxycortisol and 17‐hydroxyprogesterone concentrations, a lower response of androstenedione to 1–24 adrenocorticotropin, and an almost significant decrease in free testosterone levels, suggesting that Arg148 alleles in the gp130 gene have a protective effect against androgen excess and adrenal hyperactivity.

Discussion: Polymorphisms in the gp130 and IL6R‐α loci influence hyperandrogenism and obesity, respectively. Our present results further suggest that proinflammatory genotypes are involved in the pathogenesis of these common metabolic disorders.
Use of Glucose, Insulin, and C‐Reactive Protein to Determine Need for Glucose Tolerance Testing
Authors: Thompson Warren G. , Bergstralh Erik J. , Slezak Jeffrey M.
Published: April 2008

Objective: Glucose intolerance has been shown to be a better predictor of morbidity and mortality than impaired fasting glucose. However, glucose tolerance tests are inconvenient and expensive. This study evaluated the relative frequencies of glucose intolerance and impaired fasting glucose and sought to determine if 2‐hour glucose could be predicted from simple demographic and laboratory data in an obese population.

Research Methods and Procedures: Eighty‐nine obese subjects (median BMI 35 kg/m2, range 30 to 40 kg/m2) underwent glucose tolerance testing. Using step‐wise linear and logistic regression analysis, fasting glucose, high‐sensitivity C‐reactive protein (hsCRP), fasting insulin, high‐density lipoprotein cholesterol, triglycerides, weight, height, BMI, waist circumference, hip circumference, waist‐to‐hip ratio, sex, and age were assessed as predictors of glucose intolerance.

Results: Impaired glucose tolerance was more prevalent (27%) than impaired fasting glucose (5.6%). Only fasting glucose and hsCRP were significant (p < 0.05) independent predictors of impaired 2‐hour glucose (>140 mg/dL). A fasting glucose ≥ 100 mg/dL or an hsCRP > 0.32 mg/dL (upper quartile of the normal range) detected 81% (sensitivity) of obese subjects with impaired glucose tolerance; however, specificity was poor (46%). Fasting insulin ≥ 6 μU/mL had better sensitivity (92%) but poorer specificity (30%).

Discussion: Impaired glucose tolerance is more common than impaired fasting glucose in an obese population. Possible strategies to avoid doing glucose tolerance tests in all obese patients would be to do glucose tolerance testing only in those whose fasting glucose is ≥ 100 mg/dL or whose hsCRP exceeds 0.32 mg/dL or those whose fasting insulin is ≥ 6 μU/mL.
Impact of Diet‐Induced Weight Loss on the Cardiac Autonomic Nervous System in Severe Obesity
Authors: Poirier Paul , Hernandez Teri L. , Weil Kathleen M. , Shepard Trudy J. , Eckel Robert H.
Published: April 2008

Objective: To determine the impact of diet‐induced weight loss on cardiac autonomic nervous system modulation and arrhythmias in subjects with severe obesity and the influence of a high‐fat or a high‐carbohydrate diet regimen on heart rate variability in reduced‐obese individuals.

Research Methods and Procedures: Eight severely obese subjects (BMI ≥ 40.0 kg/m2) underwent a 3‐month weight loss program followed by a 3‐month reduced‐weight maintenance regimen. Thereafter, each subject was admitted for an inpatient period of 17 days on two separate occasions. A high‐carbohydrate (60%) or high‐fat (55%) diet of appropriate energy content for weight maintenance was prescribed during each inpatient phase. Heart rate variability was derived from a 24‐hour Holter monitoring system in all subjects during their inpatient stay. Cardiac Holter monitoring was performed at three occasions (baseline, diet phase I, and diet phase II), including the second night of a two overnight calorimetry chamber stay.

Results: After the diet regimen, there was a 10% decrease in weight. There were no significant changes in systolic and diastolic blood pressure, arrhythmias, glucose, insulin, total cholesterol, low‐density lipoprotein‐cholesterol, high‐density lipoprotein‐cholesterol, respiratory exchange ratio, and resting energy expenditure between experiments. Mean heart rate was lower after weight loss compared with baseline (p < 0.001). After weight loss, there was an increase in the parasympathetic indices of heart rate variability showing an increase in cardiac vagal modulation (all p < 0.05).

Discussion: Weight loss is associated with significant improvement in autonomic cardiac modulation through enhancement of parasympathetic modulation, which clinically translates into a decrease in heart rate.