bluuebunny/crossref_metadata_2025 huggingface dataset:
Food for thought: the role of dietary flavonoids in enhancing human memory, learning and neuro-cognitive performance
Authors: Spencer Jeremy P. E.
Published: April 2008

Emerging evidence suggests that dietary-derived flavonoids have the potential to improve human memory and neuro-cognitive performance via their ability to protect vulnerable neurons, enhance existing neuronal function and stimulate neuronal regeneration. Long-term potentiation (LTP) is widely considered to be one of the major mechanisms underlying memory acquisition, consolidation and storage in the brain and is known to be controlled at the molecular level by the activation of a number of neuronal signalling pathways. These pathways include the phosphatidylinositol-3 kinase/protein kinase B/Akt (Akt), protein kinase C, protein kinase A, Ca–calmodulin kinase and mitogen-activated protein kinase pathways. Growing evidence suggests that flavonoids exert effects on LTP, and consequently memory and cognitive performance, through their interactions with these signalling pathways. Of particular interest is the ability of flavonoids to activate the extracellular signal-regulated kinase and the Akt signalling pathways leading to the activation of the cAMP-response element-binding protein, a transcription factor responsible for increasing the expression of a number of neurotrophins important in LTP and long-term memory. One such neurotrophin is brain-derived neurotrophic factor, which is known to be crucial in controlling synapse growth, in promoting an increase in dendritic spine density and in enhancing synaptic receptor density. The present review explores the potential of flavonoids and their metabolite forms to promote memory and learning through their interactions with neuronal signalling pathways pivotal in controlling LTP and memory in human subjects.
Wrench capabilities of planar parallel manipulators. Part I: Wrench polytopes and performance indices
Authors: Firmani Flavio , Zibil Alp , Nokleby Scott B. , Podhorodeski Ron P.
Published: April 2008

This paper is organized in two parts. In Part I, the wrench polytope concept is presented and wrench performance indices are introduced for planar parallel manipulators (PPMs). In Part II, the concept of wrench capabilities is extended to redundant manipulators and the wrench workspace of different PPMs is analyzed. The end-effector of a PPM is subject to the interaction of forces and moments. Wrench capabilities represent the maximum forces and moments that can be applied or sustained by the manipulator. The wrench capabilities of PPMs are determined by a linear mapping of the actuator output capabilities from the joint space to the task space. The analysis is based upon properly adjusting the actuator outputs to their extreme capabilities. The linear mapping results in a wrench polytope. It is shown that for non-redundant PPMs, one actuator output capability constrains the maximum wrench that can be applied (or sustained) with a plane in the wrench space yielding a facet of the polytope. Herein, the determination of wrench performance indices is presented without the expensive task of generating polytopes. Six study cases are presented and performance indices are derived for each study case.
Internet-Based Self-Help Training for Children and Adolescents with Recurrent Headache: A Pilot Study
Authors: Trautmann Ellen , Kröner-Herwig Birgit
Published: April 2008

We report the results of a randomized controlled trial that compared the efficacy of an internet-based self-help treatment for paediatric headache including chat communication (cognitive-behavioural treatment, CBT) with an internet-based psychoeducation intervention (EDU). In the CBT group, significant pre- to post-treatment decreases were found for headache frequency and pain catastrophizing, but not for headache intensity or duration. In the EDU group none of the variables (frequency, intensity, duration, pain catastrophizing) showed improvement. No significant between group differences were found for headache variables and pain catastrophizing at post-treatment. The patients reported high satisfaction with the internet-based training and a good patient-trainer-alliance. Results were maintained at 6-month follow-up. Due to the small sample size, no general conclusions can be drawn regarding the efficacy of the internet-based training regarding the outcome variables, but the training was well accepted by patients. Further research is necessary to evaluate the therapeutic potential of such interventions.
Association of BMI and nutritional habits with hypertension in the adult population of Croatia
Authors: Uhernik Ana Ivičević , Erceg Marijan , Milanović Sanja Musić
Published: April 2008

Objective

The purpose of the present study was to investigate the distribution of hypertension, its nutritional and other determinants and their association in Croatia.

Design

Population-based, cross-sectional study.

Setting

Croatia.

Subjects

Representative random sample of 9070 adults (18 years and older) from all Croatian regions, selected using multistage sampling.

Results

Overall prevalence of hypertension (arterial blood pressure ≥140/90 mmHg) in Croatia was 45·5 %, of which 40 % were newly diagnosed hypertensives. There was no difference in the percentage of hypertensives between the continental and Mediterranean parts of Croatia. Newly diagnosed hypertension was found to be positively associated with increased BMI, age and alcohol consumption in the total sample and with moderate consumption of coffee in women, as well as inversely associated with regular consumption of fruits and vegetables in the total sample and high consumption of coffee in the total sample and in men. No association with newly diagnosed hypertension was recorded for use of animal fat, consumption of whole milk, smoked meat products, for adding salt, smoking and leisure-time physical activity.

Conclusions

Hypertension is a major public health problem in both continental and Mediterranean parts of Croatia. Maintenance of normal body mass, its reduction if already increased, and regular consumption of fruits and vegetables are proposed as priorities for primary prevention of hypertension in Croatia.
Die deutsche Version des Life-Orientation-Tests (LOT-R) zum dispositionellen Optimismus und Pessimismus
Authors: Glaesmer Heide , Hoyer Jürgen , Klotsche Jens , Herzberg Philipp Yorck
Published: April 2008

Zusammenfassung. Die Relevanz des Konstruktes Optimismus für eine Vielzahl psychologischer und medizinischer Bereiche ist in zahlreichen Studien eindrucksvoll demonstriert worden. Das in der Forschung mit Abstand am häufigsten eingesetzte Messinstrument zur Erfassung des dispositionellen Optimismus ist der Life-Orientation-Test (LOT-R). Die deutsche Übersetzung des LOT-R wird vorgestellt und anhand von Daten von 4938 Personen im Alter von 18-101 Jahren geprüft. Es werden psychometrische Kennwerte, Gütekriterien und Normwerte sowohl für die Subskalen Optimismus und Pessimismus als auch für die Gesamtskala berichtet. Damit liegt eine verbesserte Basis für den Forschungseinsatz und die vergleichende Bewertung von Befunden mit diesem Instrument vor.
Degassing of metamorphic carbon dioxide from the Nepal Himalaya
Authors: Evans Matthew J. , Derry Louis A. , France‐Lanord Christian
Published: April 2008

Geothermal activity is common at the foot of the Higher Himalaya near the Main Central Thrust (MCT), Nepal Himalaya. We have sampled hot springs along a 150 km stretch of the Himalayan front and find that they carry large fluxes of CO2 derived from metamorphic reactions. Hot spring fluids are saturated with CO2, have [DIC] from 1.3 to >100 mmol kg−1 and have δ13CDIC values from −13‰ to +13‰(PDB). Analysis of CO2 released by decrepitation of fluid inclusions from syn‐ and postdeformational quartz veins indicate that crustal fluids had δ13C from −15‰ to +2‰(PDB), consistent with production of CO2 from both thermal decomposition of organic matter and decarbonation at depth. Modeling of the hot spring fluid compositions indicates that they are strongly degassed. Combining our degassing calculations with estimates of the fraction of hydrothermal alkalinity in local rivers shows that the metamorphic degassing flux of CO2 in the 32,000 km2 Narayani basin of the central Himalaya is >1.3 × 1010 mol a−1, exceeding the calculated consumption of CO2 by chemical weathering for the Narayani River basin by a factor of four. Our study implies that the net impact of Himalayan orogenesis on the carbonate‐silicate geochemical cycle is not large‐scale drawdown of CO2 because the weathering sink is substantially offset or even exceeded by the metamorphic source.
Comment on “Abrupt environmental change in Canada's northernmost lake inferred from fossil diatom and pigment stratigraphy” by Dermot Antoniades et al.
Authors: Gajewski K.
Published: April 2008

Antoniades et al. [2007; hereinafter referred to as A07] present an analysis of a 19‐cm lake sediment core from Ward Hunt Island from northern Canada. They conclude that a significant and abrupt change in the aquatic communities occurred in this lake during the past 2 centuries that was unusual with respect to the previous 8ka. In the paper, and especially in quotes to the press (e.g., http://www.cbc.ca; http://www.sciencedaily.com; http://scitizen.com) the authors conclude that their results, along with those from Smol et al. [2005] provide evidence for amplification of climates with latitude due to human caused global warming, an event unique in the past 8 ka. However, there are a number of problems in these data and flaws in the author's interpretations that render their results questionable. Their conclusions do not hold up to scrutiny as they do not concord with other information we have about climate variability in the Arctic. I have four major comments on the data, and several on the interpretation.
CALIPSO lidar observations of the optical properties of Saharan dust: A case study of long‐range transport
Authors: Liu Zhaoyan , Omar Ali , Vaughan Mark , Hair Johnathan , Kittaka Chieko , Hu Yongxiang , Powell Kathleen , Trepte Charles , Winker David , Hostetler Chris , Ferrare Richard , Pierce Robert
Published: April 2008

An extensive dust storm originating on 17 August 2006 in North Africa was observed and tracked by the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar. Over the next several days, the dust layer moved westward across the Atlantic Ocean and into the Gulf of Mexico. The initial stages of the event were examined using a sequence of CALIPSO measurements. The first of these was acquired very near the source on 18 August. Successive measurements were made over the Atlantic Ocean on 19 and 20 August, at respective locations approximately ∼1300 km and ∼2400 km from the source region. The later stages of the event were assessed using measurements acquired by the NASA Langley Research Center airborne HSRL over the Gulf of Mexico on 28 August. Within the free troposphere, the intrinsic optical properties of the dust remain relatively unchanged for the first 3 d of transport over the Atlantic Ocean. This is consistent with previous in situ measurements that have shown that there is little change in the size distribution of dust as it crosses the Atlantic. After the 10 d journey to the Gulf of Mexico, some changes are seen in the lidar ratios, the backscatter color ratio, and the optical depth ratio. The linear depolarization ratio appears to remain essentially constant (∼0.32) at all four locations mentioned above, demonstrating a notable consistency in the dust particle nonsphericity. The measured 532 nm lidar ratios are 41 ± 3, 41 ± 4, 41 ± 6 and 45.8 ± 0.8 sr, respectively, at locations near the source, over the Atlantic Ocean, and in the Gulf of Mexico. The corresponding 1064 nm lidar ratios are 52 ± 5, 55 ± 5, 54 ± 13 and 44 ± 8.3 sr. The 532 nm lidar ratios are consistent with previous measurements and with CALIPSO's prelaunch models. The lidar ratios retrieved at 1064 nm are somewhat larger than would be expected on the basis of existing modeling studies. The backscatter color ratios are 0.74 ± 0.07, 0.75 ± 0.08, 0.72 ± 0.04 and 0.62 ± 0.01, and the optical depth ratios are 0.97 ± 0.02, 1.01 ± 0.05, 0.93 ± 0.17 and 0.62 ± 0.13, respectively.
Trace gas and aerosol interactions in the fully coupled model of aerosol‐chemistry‐climate ECHAM5‐HAMMOZ: 2. Impact of heterogeneous chemistry on the global aerosol distributions
Authors: Pozzoli L. , Bey I. , Rast S. , Schultz M. G. , Stier P. , Feichter J.
Published: April 2008

We use the ECHAM5‐HAMMOZ aerosol‐chemistry‐climate model to quantify the influence of trace gas–aerosol interactions on the regional and global distributions and optical properties of aerosols for present‐day conditions. The model includes fully interactive simulations of gas phase and aerosol chemistry including a comprehensive set of heterogeneous reactions. We find that as a whole, the heterogeneous reactions have only a small effect on the SO2 and sulfate burden because of competing effects. The uptake of SO2 on dust and sea salt decreases the SO2 concentrations while the decrease in OH (that results from the uptake of HO2, N2O5, and O3) tends to increase SO2 (because of reduced oxidation). The sulfate formed in sea salt aerosols from SO2 uptake accounts for 3.7 Tg(S) a−1 (5%) of the total sulfate production. Uptake and subsequent reaction of SO2 on mineral dust contributes to a small formation of sulfate (0.55 Tg(S) a−1, <1%), but is responsible for the coating of mineral dust particles, resulting in an extra 300 Tg a−1 of dust being transferred from the insoluble to the soluble mixed modes. The burden of dust in the insoluble modes is reduced by 44%, while the total burden is reduced by 5% as a result of enhanced wet deposition efficiency. Changes in the sulfur cycle affect the H2SO4 concentrations and the condensation of H2SO4 on black carbon. Accounting for heterogeneous reactions enhances the global mean burden of hydrophobic black carbon particles by 4%. The changes in aerosol mixing state result only in a small change in the global and annual aerosol optical depth (AOD) and absorption optical depth (ABS), but have significant implications on regional and seasonal scale. For example, in the main polluted regions of the Northern Hemisphere, AOD and ABS increase by 10–30% and up to 15%, respectively, in winter.
Dynamics of the middle atmosphere as simulated by the Whole Atmosphere Community Climate Model, version 3 (WACCM3)
Authors: Richter Jadwiga H. , Sassi Fabrizio , Garcia Rolando R. , Matthes Katja , Fischer Chris A.
Published: April 2008

The Whole Atmosphere Community Climate Model, version 3 (WACCM3) is a state‐of‐the‐art climate model extending from the Earth's surface to the lower thermosphere. In this paper we present a detailed climatology of the dynamics of the middle atmosphere as represented by WACCM3 at various horizontal resolutions and compare them to observations. In addition to the mean climatological fields, we examine in detail the middle atmospheric momentum budget as well as several lower and upper atmosphere coupling phenomena including stratospheric sudden warmings, the 2‐day wave, and the migrating diurnal tide. We find that in large part, differences between WACCM3 and observations and the mean state of the model at various horizontal resolutions are related to gravity wave drag, which is parameterized in WACCM3 (and similar models). All three lower and upper atmosphere coupling processes examined show high sensitivity to the model's resolution.
Columbia Hills, Mars: Aeolian features seen from the ground and orbit
Authors: Greeley Ronald , Whelley Patrick L. , Neakrase Lynn D. V. , Arvidson Raymond E. , Bridges Nathan T. , Cabrol Nathalie A. , Christensen Philip R. , Di Kaichang , Foley Daniel J. , Golombek Matthew P. , Herkenhoff Kenneth , Knudson Amy , Kuzmin Ruslan O. , Li Ron , Michaels Timothy , Squyres Steven W. , Sullivan Robert , Thompson Shane D.
Published: April 2008

Abundant wind‐related features occur along Spirit's traverse into the Columbia Hills over the basaltic plains of Gusev Crater. Most of the windblown sands are probably derived from weathering of rocks within the crater, and possibly from deposits associated with Ma'adim Vallis. Windblown particles act as agents of abrasion, forming ventifacts, and are organized in places into various bed forms. Wind‐related features seen from orbit, results from atmospheric models, and considerations of topography suggest that the general wind patterns and transport pathways involve: (1) winter nighttime winds that carry sediments from the mouth of Ma'adim Vallis into the landing site area of Spirit, where they are mixed with locally derived sediments, and (2) winter daytime winds that transport the sediments from the landing site southeast toward Husband Hill; similar patterns occur in the summer but with weaker winds. Reversals of daytime flow out of Gusev Crater and nighttime wind flow into the crater can account for the symmetry of the bed forms and bimodal orientations of some ventifacts.
Spatiotemporal variability in peatland subsurface methane dynamics
Authors: Strack M. , Waddington J. M.
Published: April 2008

Peatlands are large natural sources of atmospheric methane (CH4). While many studies have measured CH4 emissions to the atmosphere, less is known about the stock and residence time of subsurface CH4. In this study we examined dissolved CH4 concentration in near‐surface peatland pore waters of a poor fen near Québec City, Canada, in order to (1) investigate the variability in and potential controls on these concentrations and (2) combine measured dissolved CH4 concentration with estimated bubble CH4 stock and measured CH4 fluxes to estimate the mean residence time of subsurface CH4. Concentrations ranged from 1 to 450 μM during both study seasons. Depth profiles were generally consistent at one location within the peatland throughout the sampling period but varied between locations. Patterns with depth were not well correlated to pore water pH or EC; however, changes in CH4 concentration through time in the upper 30 cm were related to temperature and water table at some locations. Depth profiles taken at 2‐ to 5‐cm intervals revealed discrete concentration “spikes” which were often maintained throughout the season and are likely related to bubble CH4 dynamics. Estimated subsurface CH4 stocks indicate that even when relatively low bubble volume (5% of peat volume) is assumed, bubble CH4 accounted for greater than half of total stocks. Calculated mean residence times were 28–120 days. This implies that CH4 flux may lag changes in water table and temperature which happen on shorter timescales (hours or days). To improve our description of subsurface CH4 stocks, links between dissolved and bubble CH4 stocks and peatland CH4 residence time, coincident measurement of pore water CH4 concentrations, entrapped gas content and composition, diffusive CH4 flux, and ebullition are required.
Spatial patterns of soil nutrients in two southern African savannas
Authors: Okin G. S. , Mladenov N. , Wang L. , Cassel D. , Caylor K. K. , Ringrose S. , Macko S. A.
Published: April 2008

Savannas are extensive, seemingly stable mixtures of grasses and trees that are thought to result from a combination of facilitation, competition, and disturbance. Here, we study the spatial distribution in surface soils of soil organic matter and macronutrients at two savanna sites along the Kalahari Transect in southern Africa: a dry site with approximately 350 mm of precipitation annually and a wet site with approximately 950 mm of precipitation annually. The concentrations of total organic carbon, total nitrogen (TN), chloride, sulfate, phosphate, and (nitrate + nitrite) were analyzed in surface soils from these sites using a variety of traditional and geostatistical analyses. Soil nutrient content is generally higher at the wet site (e.g., 0.039% TN versus 0.023% TN, 0.67 μg/g PO4−3 versus 0.30 μg/g PO4−3, and 3.44 μg/g (NO3− + NO2−) versus 1.79 μg/g (NO3− + NO2−)), though there is considerable variation among sample populations from different vegetation covers. Our results indicate that the dry site is also more spatially heterogeneous than the wet site. At the dry site, where the range of spatial autocorrelation for TN, SO4−2, PO4−3, and (NO3− + NO2−) is 8.5 m, 8.5 m, 8.7 m, and 7.3 m, respectively, the spacing of all woody vegetation (both shrubs (woody plants ≤ 2 m) and trees (woody plants > 2 m)) contributes to the patterning of soil resources. At the wet site, where the range of spatial autocorrelation for TN, SO4−2, and PO4−3 is 4.6 m, 6.1 m, and 10.2 m, respectively, only trees contribute to the patterning of soil resources, though (NO3− + NO2−) displays a purely random distribution. We also find weak evidence that nitrogen may not be the, or the only, limiting nutrient in these ecosystems.
AGU Mass Media Fellow Discovers “Wow” Factor
Authors: Larson Ben
Published: April 2008

I clearly remember the first time I realized that something was amiss with my perception of science.

It was the summer of 2001. I was a second‐year graduate student studying hydrothermal chemistry at the University of Washington, in Seattle. At the moment of my realization, I was in New York exploring an exhibit about hydrothermal vents at the American Museum of Natural History. As I was inspecting an intricate diorama of a remotely operated vehicle diving on a vent field, my younger brother, fascinated by the setup, asked, “How come when you talk about this stuff, it always sounds so complicated and boring?” I didn't have a good answer.
Exploring the Secrets of the Aurora, 2nd edition
Authors: Robinson Robert M.
Published: April 2008

Pioneers in science invariably have struggled with ideas that future scientists learn and accept with almost casual indifference. Perhaps the basis for progress in science is that the energy and creativity of young scientists need not be expended on rediscovering truths that earlier scientists spent whole careers uncovering. Nevertheless, an appreciation for the process by which these truths were painstakingly unveiled is a lesson from which scientists of all ages can learn. Exploring the Secrets of the Aurora, by Syun‐Ichi Akasofu, should be read for that reason alone, but the book has other merits as well.
Promoting Space Weather Studies in Eastern Europe and Western Asia
Authors: Crosby Norma B. , Babayev Elchin S.
Published: April 2008

A regional network and an international refereed scientific journal have been established to promote space weather studies in southeastern and east central Europe and in the Caucasus region. The main impetus behind establishing the Balkan, Black Sea, and Caspian Sea Regional Network on Space Weather Studies is to strengthen activities in the region in the field of space science—especially space weather‐related studies—under the umbrella of the International Heliophysical Year (IHY).

The network promotes bilateral and multilateral joint projects and collaborations among network countries; the training of young scientists from network countries at participating institutions; and the organizing of annual regional summer/winter schools and colloquia on solar‐terrestrial physics and network meetings in different network countries. In addition, the network promotes activities to popularize the knowledge of solar‐terrestrial physics through network member‐written popular scientific articles published on the network's Web site and in other network country publications. The network also promotes school competitions for proposals for joint/collaborative astrophysical observations. It also promotes “astronomy olympiads,” a competition to test young people on their knowledge of astronomy that remains popular in former Soviet block countries.
Outstanding Student Paper Awards
Authors: Anonymous
Published: April 2008

The following members received Outstanding Student Paper Awards at the 2007 AGU Fall Meeting, in San Francisco, Calif. Awards for other sections and focus groups will be announced in subsequent issues of Eos.
Hominin Environments in the East African Pliocene: An Assessment of the Faunal Evidence
Authors: Ruddiman William
Published: April 2008

This volume grew out of two workshops (Tempe, Ariz., in 2003, and Washington, D.C., in 2004) that brought together scientists who have explored the East African environmental context during the millions of years in which hominins—including our ancestors—evolved. The community of people doing this kind of work is relatively small, in part because it requires long intervals of walking under a tropical Sun looking for outcrops that contain suitable numbers of fossils.

Few sites are excavated because the density of fossil remains in undisturbed sedimentary rock is usually too low to make such an effort worthwhile. Nature comes to the fossil hunter's aid by concentrating bones in sites favored by erosion. The most promising of these sites are then explored by surface grid surveys that carefully document the overall context in which the fossils occur, in order to determine the physical (sedimentary), geochemical, and biotic processes that left the deposits. In the end, this meticulous work yields vital clues to critical questions: When and where did our species evolve? And how?
Mineral catalyzed organic synthesis in hydrothermal systems: An experimental study using time‐of‐flight secondary ion mass spectrometry
Authors: Fu Qi , Foustoukos Dionysios I. , Seyfried William E.
Published: April 2008

Hydrothermal fluids enriched in hydrocarbons of apparent abiotic origin vent from Fe‐Ni sulfide bearing chimney structures on the seafloor at slow spreading mid‐ocean ridges. Here we show results from a hydrothermal experiment using carbon isotope labeling techniques and mineral analytical data that indicate that pentlandite ((Fe2Ni7)S8) enhances formation of C2 and C3 alkanes, while also contributing to the formation of other more complex hydrocarbons, such as alcohols and carboxylic acids. ToF‐SIMS data reveal the existence of isotopically anomalous carbon on the pentlandite surface, and thus, for the first time, provide unambiguous evidence that mineral catalyzed surface reactions play a role in carbon reduction schemes under hydrothermal conditions. We hypothesize that hydroxymethylene (‐CHOH) serves as intermediary facilitating formation of more complex organic compounds. The experimental results provide an explanation for organic synthesis in ultramafic‐hosted hydrothermal systems on earth, and on other water‐enriched planetary bodies as well.
Six‐Month Treatment of Obesity with Sibutramine 15 mg; A Double‐Blind, Placebo‐Controlled Monocenter Clinical Trial in a Hispanic Population
Authors: Cuellar Guillermina Elisa Martínez , Ruiz Alberto Martínez , Monsalve Maria Cristina Revilla , Berber Arturo
Published: April 2008

Objective: To evaluate the safety and efficacy of sibutramine 15 mg by mouth once per day in obese patients over a period of 6 months.

Research Methods and Procedures: A monocenter, double‐blind, placebo controlled, parallel, prospective clinical trial was carried out. Sixty‐nine male and female obese patients (body mass index [BMI] > 30 kg/m2) aged 16 to 65 years entered the trial.

Results: 22 of 35 patients in the sibutramine group and 9 of 34 patients in the placebo group completed the trial. The high dropout rate in the sibutramine group was due to adverse events in 3 cases, lack of efficacy (as judged by patients) in 7, loss to follow‐up in 2, and an orthopedic device being worn in 1; in the placebo group the dropouts were ascribed to lack of efficacy (as judged by patients) in 17 cases and to loss to follow‐up in 8 cases. Using the method of last observation carried forward, the weight loss in the sibutramine group was 10.27 kg (95% confidence intervals [95% CI] 7.66; 13.07) and 1.26 kg (95% CI 0.3; 2.23) in the placebo group. The BMI loss was 4.17 kg/m2 (95% CI 3.11; 5.22) in the sibutramine group and 0.53 kg/m2 (95% CI 0.13; 0.92) in the placebo group. The waist circumference reduction was 12.51 cm (95% CI 9.25; 15.77) in the sibutramine group and 3.26 cm (95% CI 1.38; 5.14) in the control group (p < 0.05 by paired Student's t test for all the intragroup comparisons). Twenty‐three sibutramine patients had 34 adverse events, the most frequent adverse events in the sibutramine group were upper respiratory tract infections (n = 6) and constipation (n = 6); 16 placebo patients had 21 adverse events. Three sibutramine patients withdrew their informed consent when they had adverse events.

Discussion: The results show that sibutramine induces significant loss of body weight and waist circumference. Cardiovascular function was not significantly affected by sibutramine. Sibutramine was well tolerated by most of the patients.
The Expression of Peroxisome Proliferator‐Activated Receptor γ in Pig Fetal Tissue and Primary Stromal‐Vascular Cultures
Authors: Kim Hyun‐Sook , Hausman Gary J. , Hausman Dorothy B. , Martin Roy J. , Dean Roger G.
Published: April 2008

Objective: This study was designed to determine when peroxisome proliferator‐activated receptor γ (PPARγ) is expressed in developing fetal adipose tissue and stromal‐vascular adipose precursor cells derived from adipose tissue. In addition we examined developing tissue for CCAAT/enhancer‐binding protein β (C/EBPβ) expression to see if it was correlated with PPARγ expression. Pituitary function and hormones involved with differentiation (dexamethasone and retinoic acid) were also tested for their effects on PPARγ expression to determine if hormones known to affect differentiation also effect PPARγ expression in vivo and in cell culture.

Research Methods and Procedures: Developing subcutaneous adipose tissues from the dorsal region of the fetal pig were collected at different gestation times and assayed using Western blot analysis to determine levels of PPARγ and C/EBPβ. Hypophysectomy was performed on 75‐day pig fetuses and tissue samples were then taken at 105 days for Western blot analysis. Adipose tissue was also taken from postnatal pigs to isolate stromal‐vascular (S‐V) cells. These adipose precursor cells were grown in culture and samples were taken for Western blot analysis to determine expression levels of PPARγ.

Results: Our results indicate that PPARγ is expressed as early as 50 days of fetal development in adipose tissue and continues through 105 days. Expression of PPARγ was found to be significantly enhanced in adipose tissue from hypophysectomized fetuses at 105 days of fetal development (p < 0.05). C/EBPβ was not found in 50‐ or 75‐day fetal tissues and was found only at low levels in 105‐day tissues. C/EBPβ was not found in hypophysectomized (hypoxed) 105‐day tissue where PPARγ was elevated. S‐V cells freshly isolated from adipose tissue of 5‐ to 7‐day postnatal pigs showed the expression of PPARγ1. When S‐V cells were cultured, both PPARγ1 and 2 were expressed after the first day and continued as cells differentiated. High concentrations of retinoic acid decreased PPARγ expression in early S‐V cultures (p < 0.05).

Discussion: Our data indicate that PPARγ is expressed in fetal adipose tissue very early before distinct fat cells are observed and can be expressed without the expression of C/EBPβ. The increase in PPARγ expression after hypophysectomy may explain the increase in fat cell size under these conditions. Adipose precursor cells (S‐V cells) from 5‐ to 7‐day postnatal pigs also express PPARγ in the tissue before being induced to differentiate in culture. Thus S‐V cells from newborn pig adipose tissue are probably more advanced in development than the 3T3‐L1 cell model. S‐V cells may be in a state where PPARγ and C/EBPα are expressed but new signals or vascularization are needed before cells are fully committed and lipid filling begins.
Obesity and Physical and Emotional Well‐Being: Associations between Body Mass Index, Chronic Illness, and the Physical and Mental Components of the SF‐36 Questionnaire
Authors: Doll Helen A. , Petersen Sophie E. K. , Stewart‐Brown Sarah L.
Published: April 2008

Objective: To clarify the associations between obesity and health‐related quality of life by exploring the associations between physical and emotional well‐being in relation to obesity and the presence of other chronic illness.

Research Methods and Procedures: The study data were collected as part of a postal‐survey within the old Oxford Regional Health Authority of England in 1997. Completed questionnaires were returned by 8889 of 13,800 randomly selected adults aged 18 to 64 years. The main outcome measures were body mass index in five categories (underweight, normal weight, overweight, moderately obese, morbidly obese); chronic illness status (any vs. none and number of such illnesses 0, 1 to 2, 3+); and mean SF‐36 questionnaire score in two summary component measures reflecting physical and emotional well‐being.

Results: Of the subjects, 31% were overweight and an additional 11% were obese. Body mass index was significantly associated with health status, but the pattern varied according to whether the measure reflected physical or emotional well‐being. Physical, but not emotional, well‐being deteriorated markedly with increasing degree of overweight and was limited in subjects who were obese but had no other chronic condition; subjects with chronic illnesses other than obesity were compromised in both dimensions. In terms of the number of chronic illnesses reported, the additional presence of obesity was associated with a significant deterioration in physical but not emotional well‐being.

Discussion: Overweight and obesity are associated with poor levels of subjective health status, particularly in terms of physical well‐being. The limitations in emotional well‐being that are reported here and in other studies may be a result of confounding by the presence of accompanying chronic illness.
Prevalence of Pre‐obesity and Obesity in Urban Adult Mexicans in Comparison with Other Large Surveys
Authors: Arroyo Pedro , Loria Alvar , Fernández Victoria , Flegal Katherine M. , Kuri‐Morales Pablo , Olaiz Gustavo , Tapia‐Conyer Roberto
Published: April 2008

Objective: 1. To estimate the prevalence of pre‐obesity and obesity in a 1992 to 1993 national survey of the Mexican urban adult population. 2. To compare our findings with other national surveys and with data for Mexican Americans.

Research Methods and Procedures: The national representative sample of the Mexican urban adult population included 8462 women and 5929 men aged 20 to 69 years from 417 towns of >2500 people. Body mass index (BMI), calculated from measured weight and height, was classified using the World Health Organization categories of underweight (BMI < 18.5 kg/m2), normal weight (BMI 18.5 to 24.9 kg/m2), pre‐obesity (PreOB = BMI 25 to 29.9 kg/m2) and obesity (OB = BMI 30+ kg/m2). Estimates for Mexican Americans were calculated from U.S. survey data.

Results: Overall, 38% of the Mexican urban adult population were classified as pre‐obese and 21% as obese. Men had a higher prevalence of pre‐obesity than women did at all ages, but women had higher values of obesity. Both pre‐obesity and obesity increased with age up to the age range brackets of 40 to 49 or 50 to 59 years for both men and women. Both pre‐obesity and obesity prevalence estimates were remarkably similar to data for Mexican Americans from 1982 through 1984. Comparison with other large surveys showed that countries differed more in the prevalence of obesity than of pre‐obesity, leading to differences in the PreOB/OB ratio, and that countries also differed in the gender ratio (female/male) for both pre‐obesity and obesity.

Discussion: Pre‐obesity and obesity were high in our population and increased with age. Our approach of characterizing large surveys by PreOB/OB and gender ratios appeared promising.
Familial Risk of Overweight and Obesity in the Canadian Population using the WHO/NIH Criteria
Authors: Katzmarzyk Peter T. , Pérusse Louis , Rao D. C. , Bouchard Claude
Published: April 2008

Objective: To determine the familial risk of overweight and obesity in Canada.

Research Methods and Procedures: The sample was comprised of 15,245 participants from 6377 families of the Canada Fitness Survey. The risk of overweight and obesity among spouses and first‐degree relatives of individuals classified as underweight, normal weight, pre‐obese, or obese (Class I and II) according to the WHO/NIH guidelines for body mass index (BMI) was determined using standardized risk ratios.

Results: Spouses and first‐degree relatives of underweight individuals have a lower risk of overweight and obesity than the general population. On the other hand, the risk of Class I and Class II obesity (BMI 35 to 39.9 kg/m2) in relatives of Class I obese (BMI 30 to 34.9 kg/m2) individuals was 1.84 (95% CI: 1.27, 2.37) and 1.97 (95% CI: 0.67, 3.25), respectively, in spouses, and 1.44 (95% CI:1.10, 1.78) and 2.05 (95% CI: 1.37, 2.73), respectively in first‐degree relatives. Further, the risk of Class II obesity in spouses and first‐degree relatives of Class II obese individuals was 2.59 (95% CI: −0.91, 6.09) and 7.07 (95% CI: 1.48, 12.66) times the general population risk, respectively.

Discussion: There is significant familial risk of overweight and obesity in the Canadian population using the BMI as an indicator. Comparison of risks among spouses and first‐degree relatives suggests that genetic factors may play a role in obesity at more extreme levels (Class II obese) more so than in moderate obesity.
Free Fatty Acids Are Involved in the Inverse Relationship between Hormone‐Sensitive Lipase (HSL) Activity and Expression in Adipose Tissue after High‐Fat Feeding or β3‐Adrenergic Stimulation
Authors: Berraondo Beatriz , Martínez J. Alfredo
Published: April 2008

Objective: The hormone‐sensitive lipase (HSL) is the rate‐limiting enzyme in adipose tissue lipolysis. The aim of this experimental trial was to study the effects of a β3‐adrenergic agonist (Trecadrine) on plasma fatty acids, adipocyte HSL activity, and gene expression in control and cafeteria‐induced obese animals.

Research Methods and Procedures: Control and cafeteria‐fed rats were treated with a placebo or Trecadrine during 35 days. Plasma fatty acids were measured by an enzymatic method, whereas HSL activity was assessed by using labeled triolein as substrate. Finally, HSL gene expression from white adipose tissue (WAT) was determined using a reverse transcription‐polymerase chain reaction method.

Results: Trecadrine administration reduced plasma fatty acids and HSL mRNA levels in abdominal WAT, whereas HSL activity was significantly higher in the Trecadrine‐treated obese rats than in the obese nontreated rats. Also, abdominal WAT HSL activity significantly increased, whereas WAT HSL gene expression fell in control rats treated with β3‐adrenergic agonist as compared with control untreated animals.

Discussion: In situations of fat accumulation (high‐fat feeding) or lipid mobilization (β3‐adrenergic stimulation), changes in HSL activity and HSL gene expression seem to follow a trend related to plasma fatty acids levels, as indicated by the positive correlation (r = 0.39, p < 0.05) between HSL mRNA levels and plasma fatty acids, and the negative correlation (r = −0.38, p < 0.05) between plasma fatty acids and HSL activity. Furthermore, a highly negative correlation (r = −0.59, p < 0.001) between HSL activity and HSL mRNA expression was found, in which plasma‐free fatty acids are apparently involved.
Prevalence of Sleep Apnea and Electrocardiographic Disturbances in Morbidly Obese Patients
Authors: Valencia‐Flores Matilde , Orea Arturo , Castaño Violeta A. , Resendiz Montserrat , Rosales María , Rebollar Verónica , Santiago Victoria , Gallegos José , Campos Rosa M. , González Jorge , Oseguera Jorge , García‐Ramos Guillermo , Bliwise Donald L.
Published: April 2008

Objective: To determine the prevalence of sleep apnea in morbidly obese patients and its relationship with cardiac arrhythmias.

Research Methods and Procedures: Fifty‐two consecutive morbidly obese (body mass index ≥ 40 kg/m2) outpatients from the Obesity Clinic of the National Institute of Nutrition Salvador Zubirán underwent two nights of polysomnography with standard laboratory techniques. Electrocardiographic polysomnography signals (Lead II) were evaluated by two experienced cardiologists, and sleep complaints were measured with a standard sleep questionnaire (Sleep Disorders Questionnaire). In order to make comparisons between groups with different severities of sleep‐disordered breathing, we classified the patients in four groups using the apnea‐hypopnea index (AHI): Group 1, AHI 5 < 15 (n = 10); Group 2, AHI 15 < 30 (n = 10); Group 3, AHI 30 < 65 (n = 14); Group 4, AHI ≥ 65 (n = 17).

Results: A wide range of sleep‐disordered breathing, ranging from AHI of 2.5 to 128.9 was found. Ninety‐eight percent of the sample (n = 51) had an AHI ≥ 5 (mean = 51 ± 37), and 33% had severe sleep apnea with AHI ≥ 65 with a mean nocturnal desaturation time of <65% over 135 minutes. Electrocardiographic abnormalities were present in 31% of the patients. Cardiac rhythm alterations showed an association with the level of sleep‐disordered breathing and oxygen desaturation.

Discussion: We conclude that there is a high prevalence of sleep apnea in morbidly obese patients and that the risk for cardiac arrhythmias increases in this population in the presence of a severe sleep apnea (AHI ≥ 65) with severe oxygen desaturation (Sao2 ≤ 65%).
Comparison of Zinc Reduction with Platinum Reduction for Analysis of Deuterium‐Enriched Water Samples for the Doubly Labeled Water Technique
Authors: Herd Sara L. , Vaughn William H. , Goran Michael I.
Published: April 2008

Objective: Isotope ratio mass spectrometry of hydrogen and oxygen is frequently used to determine total energy expenditure (TEE) using doubly labeled water. Conventionally, hydrogen isotope ratio is determined in hydrogen gas generated from water samples using zinc reduction. We compare this with a new automated platinum method to determine the ratios of hydrogen isotopes in deuterium‐enriched water samples.

Research Methods and Procedures: The platinum method of sample preparation was compared with the zinc method in three ways: analytical variation in deuterium enrichment (within sample; n = 51), analytical variation in TEE estimates (within sample set; n = 10), and level of agreement of TEE estimates between both methods (n = 14).

Results: For the zinc method, the standard deviation for multiple sets of triplicate 2H2O sample analysis was ±4.36‰ and ±2.07‰ for platinum. The correlation between TEE estimates when sample sets were analyzed in duplicate was r = 0.89 for zinc and r = 0.83 for platinum. The intercept and slope of the regression line were significantly different from the line of identity for duplicate TEE estimates by zinc but were not different from the line of identity for platinum. After correction for the intra‐assay variation of each method, the correlation between zinc and platinum for TEE was 0.77, and the intercept, but not the slope, of the regression was significantly different from the line of identity. The mean difference between the zinc method and the platinum method was 56 kcal/day, and the 95% confidence interval was −438 to 550 kcal/day.

Discussion: These data suggest that the platinum method is at least as reliable as the zinc method as a sample preparation technique for isotope ratio mass spectrometry of deuterium‐enriched water samples. The platinum method is also less costly and less labor‐intensive than the zinc method.
Abnormal Signal‐Averaged Electrocardiogram (SAECG) in Obesity
Authors: Lalani Atul P. , Kanna Balavenkatesh , John Joseph , Ferrick Kevin J. , Huber Michael S. , Shapiro Lawrence E.
Published: April 2008

Objective: The occurrence of small high‐frequency electrocardiogram (ECG) potentials (1 to 20 μV) seen at the end of the QRS complex and into the ST segment have been correlated with increased risk for ventricular arrhythmias and sudden cardiac death. Computer‐assisted analysis of these “late potentials” by signal‐averaged electrocardiography (SAECG) has been studied and utilized to predict the likelihood of ventricular arrhythmias in various clinical states. Obesity is associated with significant cardiovascular morbidity and sudden death. Ventricular arrhythmias are postulated causes. We studied the occurrence of late potentials in a randomly selected group of obese patients and healthy volunteers.

Research Methods and Procedures: We performed SAECG on 105 subjects. Of these, 62 were obese ambulatory patients with body mass index (BMI) of >30 kg/m2, whereas 43 were healthy asymptomatic volunteers with a BMI of <30 kg/m2. Patients with a history of clinical heart disease and pulmonary disease, electrolyte abnormalities, recent hospitalizations, or abnormal screening ECG or taking medications known to alter the QRS interval were excluded. At least 250 beats were analyzed with a noise level of <0.50 μV. Criteria of a late potential include QRS duration >114 ms, high‐frequency low amplitude >38 ms, and root‐mean‐square voltage <20 μV. Patients were divided into four subgroups based on BMI values. The prevalence of SAECG abnormalities in each BMI subgroup was studied. We utilized multiple logistic regression analysis to study the effect of obesity, hypertension, and diabetes mellitus on abnormal SAECG results.

Results: Compared to age‐ and sex‐matched healthy volunteers with BMI of <30 kg/m2, obese patients with BMI of >30 kg/m2 had significantly more abnormalities on SAECG (4.6% vs. 55%). In the obese group, the prevalence and number of abnormalities increased with increase in BMI (35% in the BMI 31 to 40 kg/m2 subgroup, 86% in the BMI 41 to 50 kg/m2 subgroup, and 100% in patients with BMI of >50 kg/m2). Multiple logistic regression analysis shows that BMI is an independent predictor variable of abnormal SAECG results in obese patients (n = 62) with BMI of >30kg/m2 as well as in all study subjects (n = 105). BMI also predicts abnormality of each abnormal SAECG criterion in both obese and all subjects. Hypertension was found to influence the QRS duration alone in obese and all subjects.

Discussion: Obesity is associated with increased occurrence of abnormal SAECG results. These abnormalities are found both in obese patients with and without hypertension and/or diabetes. Obesity is an independent predictor variable of abnormal SAECG results. A history of hypertension predicts abnormality of QRS duration only.
Metabolic and Weight Loss Effects of Long‐Term Dietary Intervention in Obese Patients: Four‐Year Results
Authors: Flechtner‐Mors Marion , Ditschuneit Herwig H. , Johnson Timothy D. , Suchard Mark A. , Adler Guido
Published: April 2008

Objective: To investigate the contribution of meal and snack replacements for long‐term weight maintenance and risk factor reduction in obese patients.

Research Methods and Procedures: Prospective, randomized, two‐arm, parallel intervention for 12 weeks followed by a prospective single‐arm 4‐year trial in a University Hospital clinic. One hundred patients, >18 years old and with a body mass index > 25 and ≤ 40 kg/m2, were prescribed a 1200 to 1500 kcal/d control diet (Group A) or an isoenergetic diet, including two meal and snack replacements (vitamin‐ and mineral‐fortified shakes, soups, and bars) and one meal high in fruits and vegetables (Group B). Following a 3 months of weight loss, all patients were prescribed the same energy‐restricted diet (1200 to 1500 kcal) with one meal and one snack replacement for an additional 4 years.

Results: All 100 patients were evaluated at 12 weeks. Mean percentage weight loss was 1.5 ± 0.4% and 7.8 ± 0.5% (mean ± SEM) for Groups A and B, respectively. At 12 weeks systolic blood pressure, plasma triacylglycerol, glucose, and insulin concentrations were significantly reduced in Group B, whereas no changes occurred in Group A. After 4 years, 75% of the patients were evaluated. Total mean weight loss was 3.2 ± 0.8% for Group A and 8.4 ± 0.8% (mean ± SEM) for Group B. Both groups showed significant improvement in blood glucose and insulin (p < 0.001), but only Group B showed significant improvement in triacylglycerol and systolic blood pressure compared to baseline values (p < 0.001).

Discussion: Providing a structured meal plan via vitamin‐ and mineral‐fortified liquid meal replacements is a safe and effective dietary strategy for obese patients. Long‐term maintenance of weight loss with meal replacements can improve certain biomarkers of disease risk.