bluuebunny/crossref_metadata_2025 huggingface dataset:
Stratospheric impact of the Chisholm pyrocumulonimbus eruption: 2. Vertical profile perspective
Authors: Fromm M. , Shettle E. P. , Fricke K. H. , Ritter C. , Trickl T. , Giehl H. , Gerding M. , Barnes J. E. , O'Neill M. , Massie S. T. , Blum U. , McDermid I. S. , Leblanc T. , Deshler T.
Published: April 2008

Extreme pyrocumulonimbus (pyroCb) blowups that pollute the stratosphere have been documented on at least five occasions. However, the frequency of these events is still uncertain. One published pyroCb case study, the Chisholm Fire in May 2001, was restricted to the convective phase and its immediate aftermath. Here and in a companion paper we describe the stratospheric impact of the Chisholm pyroCb. The companion paper focuses on nadir satellite views of the plume. This paper synthesizes a broad array of space‐, balloon‐, and ground‐based profile measurements. The Chisholm pyroCb, which we identify as the singular cause of stratospheric aerosol increase in northern spring/summer of 2001, created a doubling of the zonal average aerosol optical depth in the lowermost stratosphere. The meridional spread of the plume was from the tropics (20°N) to the high Arctic (79°N) within the first month. The stratospheric Chisholm smoke became a hemispheric phenomenon in midlatitudes and northern tropics and persisted for at least 3 months. A size‐resolved particle concentration profile over Laramie, Wyoming, indicated a lower stratospheric aerosol with a twofold to threefold increase in volume of particles with radii between 0.3 and 0.6 μm. We also find evidence of localized warming in the air masses of four of the lidar‐measured smoke layers. This work contains the first reported stratospheric smoke layers measured by lidar at Ny Ålesund, Esrange, Kühlungsborn, Garmisch‐Partenkirchen, Boulder, and Mauna Loa. In addition, the first detection of smoke‐enhanced aerosol extinction at near IR wavelengths by the Halogen Occultation Experiment (HALOE) is introduced.
Relative importance of mass and volume changes to global sea level rise
Authors: Jevrejeva S. , Moore J. C. , Grinsted A.
Published: April 2008

We examine the relationship between 50‐year‐long records of global sea level (GSL) calculated from 1023 tide gauge stations and global ocean heat content (GOHC), glacier and ice sheet melting. The lack of consistent correlation between changes in GOHC and GSL during the period 1955–2003 argues against GOHC being the dominant factor in GSL as is often thought. We provide clear evidence of the substantial and increasing role in GSL from the eustatic component (47%) compared with the contribution from increasing heat content (25%), suggesting that the primary role is being played by the melting glaciers and ice sheets. There remains about 1/4 of GSL rise unaccounted for by the best estimates of both eustatic and thermosteric effects. This fraction also exhibits large variability that is not readily associated with known causes of sea level variability. The most likely explanation of this unknown fraction is underestimated melting, climate‐driven changes in terrestrial storage components, and decadal timescale variability in global water cycle. This argues for a concerted effort to quantify changes in these reservoirs.
Long‐distance pollen transport from North America to Greenland in spring
Authors: Rousseau Denis‐Didier , Schevin Patrick , Ferrier Jackie , Jolly Dominique , Andreasen Tore , Ascanius Svend Erik , Hendriksen Svend‐Erik , Poulsen Ulrik
Published: April 2008

In the Arctic domain, there is evidence for very long distance transport of pollen grains from boreal forests to tundra environments. However, the sampling protocol used in earlier studies did not allow the determination of precise timing of the deposition of exotic grains. The ongoing “Epilobe” project monitors the deposition of exotic grains on the western and eastern coasts of Greenland utilizing wind filters, which are changed weekly throughout the entire year. A combination of the identification of tree pollen grains, the dates of deposition of the pollen on the filters, and the distribution map of the trees identified, allows the selection of modeled backward trajectories of air parcels responsible for the capture of the grains in the growing area of northeastern North America and their long‐distance transport to Greenland. A survey of data obtained from four stations, analyzed during 2004 and 2005, indicates the occurrence of a general pattern every spring, which follows the main cyclone tracks reaching this Arctic region.
Evaporation from a thin layer of wet sand
Authors: Pavia Edgar G.
Published: April 2008

Natural evaporation from wet sand is experimentally estimated by differential weigh and subsequently it is modeled empirically. The experiment consists in weighing, before and after being exposed to open‐air ambient conditions, a shallow tray containing a layer of wet sand. The difference in weigh is taken as the amount of water evaporated during the experiment. Evaporation from a tray containing water only is similarly estimated and corroborated with a graduated cylinder. The procedure was repeated 42 times during the autumn and early winter 2007–2008, at Ensenada, Mexico (31°52′N, 116°40′W). Several meteorological variables (air temperature, solar radiation, relative humidity and wind speed, among others) were recorded at the site simultaneously. The main results are (1) Evaporation from a thin layer of wet sand was modeled successfully using air temperature and solar radiation as predictors; and (2) this evaporation and evaporation from a thin layer of plain water varied similarly, but, in average, the latter was about 12% less than the former.
Response of magnetospheric boundaries to the interplanetary shock: Themis contribution
Authors: Přech L. , Němeček Z. , Šafránková J.
Published: April 2008

Several studies have been devoted to the interaction of interplanetary (IP) shocks with both characteristic Earth's magnetospheric boundaries: the bow shock and magnetopause. Non‐stationarity of this interaction requires multi‐spacecraft observations with good space and temporal coverage. We analyze a CIR generated IP shock with the normal highly inclined from the solar wind velocity. We use a large set of spacecraft orbiting in the solar wind (SOHO, Wind, ACE), near the bow shock (Cluster II) as well as in the magnetosheath (Themis A, B, C, D) and in the magnetosphere at the magnetopause vicinity (Themis E). We discuss the IP shock deformation, changes of its orientation and speed as well as the properties of a new discontinuity generated by the IP shock–bow shock interaction.
Ground‐based observational signature of a downward current channel in an active auroral arc
Authors: Michell R. G. , Lynch K. A. , Stenbaek‐Nielsen H. C.
Published: April 2008

Ground‐based images of an active auroral arc over Kaktovik, Alaska on 6 March 2005 show the evolution of an event near magnetic midnight during the expansion phase of an auroral substorm. The auroral arc developed a distinct dark stripe embedded in a region of active aurora near the poleward edge of the activity. The dark stripe was observed to form and slowly widen from 15 km to 55 km (at an assumed altitude of 100 km), over a time period of 50 seconds. A linear fit to the data gives a widening rate of 750 m/s. We compare the ground‐based signatures of this event to in situ downward‐current‐region signatures of events observed by FAST and Cluster, and show that such an auroral feature is consistent with the predictions and observations of a downward‐current region.
Surface water‐groundwater interface geomorphology leads to scaling of residence times
Authors: Cardenas M. Bayani
Published: April 2008

We know little regarding how geomorphological features along the surface‐groundwater interface collectively affect water quality and quantity. Simulations of surface water‐groundwater exchange at increasing scales across bed forms, bars and bends, and basins show that groundwater has a power‐law transit time distribution through all these features, providing a purely mechanistic foundation and explanation for temporal fractal stream chemistry. Power‐law residence time distributions are almost always attributed to spatial variability in subsurface transport properties‐ something we show is not necessary. Since the different geomorphological features considered here are typical of most landscapes, fractal stream chemistry may be universal and is a natural consequence of water exchange across multifaceted interfaces.
Preischemic Induction of TNF-α by Physical Exercise Reduces Blood-Brain Barrier Dysfunction in Stroke
Authors: Guo Miao , Lin Victoria , Davis William , Huang Tao , Carranza Aaron , Sprague Shane , Reyes Raul , Jimenez David , Ding Yuchuan
Published: April 2008

This study explores the neuroprotective action of tumor necrosis factor-α (TNF-α) induced during physical exercise, which, consequently, reduces matrix metalloproteinase-9 (MMP-9) activity and ameliorates blood—brain barrier (BBB) dysfunction in association with extracellular signal-regulated kinase 1 and 2 (ERK1/2) phosphorylation. Adult male Sprague—Dawley rats were subjected to exercise on a treadmill for 3 weeks. A 2-h middle cerebral artery occlusion and reperfusion was administered to exercised and nonexercised animals to induce stroke. Exercised ischemic rats were subjected to TNF-α inhibition and ERK1/2 by TNF-α antibody or UO126. Nissl staining of coronal sections revealed the infarct volume. Evans blue extravasation and water content evaluated BBB function. Western blot was performed to analyze protein expression of TNF-α, ERK1/2, phosphorylated ERK1/2, the basal laminar protein collagen IV, and MMP-9. The activity of MMP-9 was determined by gelatin zymography. Tumor necrosis factor-α expression and ERK1/2 phosphorylation were upregulated during exercise. Infarct volume, brain edema, and Evans blue extravasation all significantly decreased in exercised ischemic rats. Collagen IV production increased in exercised rats and remained high after stroke, whereas MMP-9 protein level and activity decreased. These results were negated and returned toward nonexercised values once TNF-α or ERK1/2 was blocked. We concluded that preischemic, exercise-induced TNF-α markedly decreases BBB dysfunction by using the ERK1/2 pathway.
Antiangiogenic Effect of Inhibitors of Cytochrome P450 on Rats with Glioblastoma Multiforme
Authors: Zagorac Drazen , Jakovcevic Danica , Gebremedhin Debebe , Harder David R
Published: April 2008

Cytochrome P450 epoxygenase catalyzes 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs) from arachidonic acid (AA). In 1996, our group identified the expression of the cytochrome P450 2C11 epoxygenase (CYP epoxygenase) gene in astrocytes. Because of our finding an array of physiological functions have been attributed to EETs in the brain, one of the actions of EETs involves a predominant role in brain angiogenesis. Blockade of EETs formation with different epoxygenase inhibitors decreases endothelial tube formation in cocultures of astrocytes and capillary endothelial cells. The intent of this investigation was to determine if pharmacologic inhibition of formation of EETs is effective in reducing capillary formation in glioblastoma multiforme with a concomitant reduction in tumor volume and increase in animal survival time. Two mechanistically different inhibitors of CYP epoxygenase, 17-octadecynoic acid (17-ODYA) and miconazole, significantly reduced capillary formation and tumor size in glial tumors formed by injection of rat glioma 2 (RG2) cells, also resulting in an increased animal survival time. However, we observed that 17-ODYA and miconazole did not inhibit the formation of EETs in tumor tissue. This implies that 17-ODYA and miconazole appear to exert their antitumorogenic function by a different mechanism that needs to be explored.
Effects of Obesity Phenotype on Coronary Heart Disease Risk Factors in Response to Weight Loss
Authors: Okura Tomohiro , Tanaka Kiyoji , Nakanishi Tomoko , Lee Dong Jun , Nakata Yoshio , Wee Seung Wan , Shimokata Hiroshi
Published: April 2008

Objective: To determine whether there is a difference in risk‐factor improvement for coronary heart disease (CHD) between the intra‐abdominal fat (IF) and subcutaneous fat (SF) obesity phenotypes after weight loss.

Research Methods and Procedures: Subjects included 55 mildly obese women (body mass index, 25 to 36 kg/m2; age range, 34 to 63 years) who had at least two of three CHD risk factors [systolic blood pressure (SBP), >140 mm Hg; total cholesterol (TC), >220 mg/dL; fasting plasma glucose, >110 mg/dL). Using computed tomography, IF obesity was classified as ≥110 cm2 of the IF area measured; subjects with <110 cm2 were classified as having SF obesity. The IF and SF obesity groups were divided into diet‐only and diet‐plus‐exercise groups. Assays and measurements were performed before and after a 14‐week (98‐day) intervention.

Results: Weight was reduced by 7 to 10 kg in each group. The IF and SF areas, SBP, diastolic blood pressure, TC, and low‐density lipoprotein‐cholesterol were significantly reduced in all groups (p < 0.01). Reduction in IF area was greater in IF obesity than in SF obesity, whereas no differences were observed in the improvement of CHD risk factors. Sample sizes needed for observing a significant difference for SBP, TC, triglycerides, and fasting plasma glucose were greater than the number of subjects in this study.

Discussion: Our results suggest that the influence of the obesity phenotype on improving CHD risk factors is not apparent. A larger study is needed to prove the validity of this finding.
Preferential Stimulation of Abdominal Subcutaneous Lipolysis after Prednisolone Exposure in Humans
Authors: Gravholt Claus Højbjerg , Dall Rolf , Christiansen Jens Sandahl , Møller Niels , Schmitz Ole
Published: April 2008

Objective: The role of cortisol in the regulation of lipolysis is not clear. This study was undertaken to explore whether a standard dose of prednisolone for 1 week would influence lipolysis in abdominal and femoral tissue.

Research Methods and Procedures: We used the microdialysis technique, the forearm technique, and indirect calorimetry, in the fasting state, after 1 week of treatment with prednisolone (30 mg daily) or placebo. Eight healthy young men (age: 25 ± 3 years; height: 181 ± 1 cm; body mass index [BMI]: 23.3 ± 0.7 kg/m2) were studied.

Results: Treatment with prednisolone induced insulin resistance (Homeostasis Model Assessment index: placebo vs. prednisolone: 7.15 ± 1.63 vs. 17.00 ± 14.26, p = 0.03), hyperinsulinemia (p = 0.01), and hyperglucagonemia (p = 0.001), whereas growth hormone concentrations were unaffected. Abdominal adipose tissue interstitial glycerol was increased during treatment with prednisolone in the face of significant hyperinsulinemia, although it barely reached statistical significance (p = 0.06). At the femoral adipose tissue depot, no difference in lipolysis was found. Arterial and venous free fatty acids (FFA) were comparable in the two situations, whereas the arteriovenous difference across the forearm was significantly decreased during treatment with prednisolone, indicating increased uptake, or decreased release of FFA. Energy expenditure (p = 0.3), repiratory quotient (p = 0.9), glucose oxidation (p = 0.9), lipid oxidation (p = 1.0), and protein oxidation (p = 0.1) were unaltered on the 2 study days.

Discussion: Short‐term treatment with a standard dose of corticosteroids induces increased abdominal adipose tissue lipolysis, as well as hyperinsulinemia, hyperglucagonemia, and insulin resistance.
Predicting Incident Diabetes in Jamaica: The Role of Anthropometry
Authors: Sargeant Lincoln A. , Bennett Franklyn I. , Forrester Terrence E. , Cooper Richard S. , Wilks Rainford J.
Published: April 2008

Objective: To evaluate the performance of the body mass index (BMI), waist circumference, waist‐to‐hip ratio (WHR), and waist‐to‐height ratio (WHTR) in predicting incident diabetes in Jamaica.

Research Methods and Procedures: A cohort of 728 nondiabetic adults (290 men and 438 women), ages 25 to 74 years and residents of Spanish Town, Jamaica, were followed for a mean of 4 years. Participants had fasting and 2‐hour postchallenge glucose concentrations measured at baseline and follow‐up.

Results: There were 51 cases of incident diabetes (17 men and 34 women). All indices were independent predictors of diabetes, and none was clearly superior. The area under the receiver operating characteristics curves (95% confidence interval) for BMI was 0.74 (0.59 to 0.88) for men and 0.62 (0.51 to 0.72) for women. For waist circumference, these values were 0.78 (0.65 to 0.91) in men and 0.61 (0.50 to 0.71) in women. Similar results were obtained for WHR and WHTR. “Optimal” cut‐off points for BMI were 24.8 kg/m2 (men) and 29.3 kg/m2 (women). For waist circumference, these were 88 cm and 84.5 cm for men and women, respectively. Corresponding values for WHR were 0.87 and 0.80 and for WHTR were 0.51 and 0.54, respectively.

Discussion: Cut‐off points for waist circumference and WHR were similar to those proposed in developed countries for women but lower in men. Waist circumference could be useful in health promotion as an alternative to BMI.
Obesity Affects Nursing‐Care Facility Admission among Whites but Not Blacks
Authors: Zizza Claire A. , Herring Amy , Stevens June , Popkin Barry M.
Published: April 2008

Objective:This study examines whether obese individuals have a greater rate of nursing care facility admission than normal weight individuals.

Research Methods and Procedures:Data from the National Health and Nutrition Examination Survey Epidemiological Follow‐up Survey were analyzed. Cox proportional hazards models were used to examine the relationship between baseline weight status and subsequent time to first nursing home admission while adjusting for sex, age, race, marital status, height, presence of children, smoking status, education, region, urban residence, income, and physical activity.

Results:Of 5960 adults 45 to 74 years old, 989 individuals were admitted to a nursing care facility over the subsequent 20 years. Body mass index (BMI) was studied using five categories: < 18.5, 18.5 to <25, 25.0 to <30, 30.0 to <35, ≥35 kg/m2. The effects of BMI differed by race: compared with those with a BMI of 18.5 to < 25 kg/m2, adults with a BMI ≥30 kg/m2or a BMI <18.5 kg/m2had a greater rate of nursing home admission in whites, whereas no relationship was found in blacks. The inclusion of time to death with nursing home admission as a joint outcome yielded similar results.

Discussion:The large increase in the prevalence of obesity coupled with the rapid expansion of the number of older Americans will likely increase the demand for nursing facility use. More research is needed to understand differences in factors related to nursing home admission among ethnic groups.
Immunomanipulation of Appetite and Body Temperature through the Functional Mimicry of Leptin
Authors: de Fanti Brant A. , Milagro Fermin I. , Lamas Oscar , Martínez‐Ansó Eduardo , Martínez J. Alfredo
Published: April 2008

Objective: Although current obesity therapies produce some benefits, there is a need for new strategies to treat obesity. A novel proposal is the use of anti‐idiotypic antibodies as surrogate ligands or hormones. These anti‐idiotypic antibodies carry an internal motif that imitates or mimics an epitope in the antigen (i.e., hormone or ligand). Thus, anti‐idiotypic antibodies to several ligands may mimic them in transducing signals when binding to their receptors.

Research Methods and Procedures: We developed an anti‐idiotypic polyclonal antibody against the region of a leptin monoclonal antibody that competitively binds leptin, mimicking the active site structure of leptin. To test whether our anti‐idiotype could also reproduce leptin functions, we examined food intake, body weight, and colonic temperature in male Wistar rats (n = 9) in response to intracerebroventricular administration of the leptin anti‐idiotype.

Results: Our leptin anti‐idiotype induced a significant reduction in food intake coupled with an increase in body temperature comparable to that of leptin. That is, the intracerebroventricular administration of 8.0 μg of leptin anti‐idiotype or 5.0 μg leptin significantly increased colonic temperature (Δ 1.9 ± 0.11 °C and Δ1.7 ± 0.12 °C, respectively). In addition, both decreased 24‐hour food intake (−26.4 ± 2.4% and −21.9 ± 2.2%) compared with the control. The gain in body weight was also decreased by acute administration of the anti‐idiotype (−1.4 ± 0.28%) and leptin (−1.1 ± 0.17%) vs. the phosphate‐buffered saline control (1.3 ± 0.15%).

Discussion: These studies revealed that the leptin anti‐idiotype inhibited food intake and enhanced heat production, mimicking leptin's central actions.
Effect of Postpartum Exercise on Mothers and their Offspring: A Review of the Literature
Authors: Larson‐Meyer Dawnine Enette
Published: April 2008

Epidemiological studies suggest that childbearing may contribute to the development of obesity. In the past 12 years, several cross‐sectional and randomized trials have addressed the effect of postpartum exercise on weight loss and/or energy balance in mostly lactating women. These studies suggest that moderate exercise without specific calorie restriction does not promote greater weight or fat loss. This may be because exercise may promote greater energy intake and/or reduced energy expenditure from nonexercise physical activity (thus preventing negative energy balance), but further research is needed. Regular exercise, however, is likely to have other important health benefits after childbirth. A few published studies suggest that postpartum exercise improves aerobic fitness, high‐density lipoprotein‐cholesterol levels, and insulin sensitivity. Exercise may also enhance psychological well‐being, but controlled clinical studies are needed. Although two published studies have addressed whether exercise training attenuates lactation‐induced bone loss, better controlled studies are needed to determine whether postpartum weight‐bearing exercise can improve bone mineral density in lactating and nonlactating women alike. In lactating women, several studies have collectively determined that neither acute nor regular exercise has adverse effects on a mother's ability to successfully breast‐feed. It needs to be determined whether a woman's participation in regular exercise after childbirth will improve her ability to mother or instill lifetime habits of regular physical activity in either herself or her offspring. Overall, published studies have established the importance of regular exercise during the postpartum period. More research, however, is needed in this important area.
Liver‐Fat Accumulation and Insulin Resistance in Obese Women with Previous Gestational Diabetes
Authors: Tiikkainen Mirja , Tamminen Marjo , Häkkinen Anna‐Maija , Bergholm Robert , Vehkavaara Satu , Halavaara Juha , Teramo Kari , Rissanen Aila , Yki‐Järvinen Hannele
Published: April 2008

Objective:We determined whether fat accumulation in the liver is associated with features of insulin resistance independent of obesity.

Research Methods and Procedures:We recruited 27 obese nondiabetic women in whom liver fat (LFAT) content was determined by proton spectroscopy, intra‐abdominal and subcutaneous fat by magnetic resonance imaging, and insulin sensitivity by the euglycemic insulin clamp technique. The women were divided based on their median LFAT content (5%) to groups with low (3.2 ± 0.3%) and high (9.8 ± 1.5%) liver fat. The groups were almost identical with respect to age (36 ± 1 vs. 38 ± 1 years in low vs. high‐LFAT), body mass index (32.2 ± 0.6 vs. 32.8 ± 0.5 kg/m2), waist‐to‐hip ratio, intra‐abdominal, subcutaneous, and total fat content.

Results:Women with high LFAT had features of insulin resistance including higher fasting serum triglyceride (1.93 ± 0.21 vs. 1.11 ± 0.09 mM,p< 0.01) and insulin (14 ± 3 vs. 10 ± 1 mU/L,p< 0.05) concentrations than women with low LFAT. The group with high LFAT also had higher 24‐hour blood pressures, and lower whole‐body insulin sensitivity compared with the low‐LFAT group.

Discussion:In obese women with previous gestational diabetes, LFAT, rather than any measure of body composition, is associated with features of insulin resistance.
Lipid Profile in the Severely Obese: Changes with Weight Loss after Lap‐Band Surgery
Authors: Dixon John B. , O'Brien Paul E.
Published: April 2008

Objective: To characterize dyslipidemia before and after weight loss in the severely obese.

Research Methods and Procedures: Five hundred fifteen subjects who had Lap‐Band surgery were followed with yearly conventional lipid profiles for up to 4 years. Preoperative data were collected from the most recent 381 subjects, and predictors of dyslipidemia were sought. One hundred seventy‐one subjects completed a 1‐year review, providing data to assess predictors of change in lipids.

Results: Favorable changes in fasting triglycerides (TG), high‐density lipoprotein‐cholesterol (HDL‐C), and total cholesterol (TC):HDL‐C ratio occurred within 1 year. All improvements were maintained up to 4 years. Male gender, central obesity, elevated fasting glucose, and insulin resistance were associated with less favorable lipid levels. Fasting plasma glucose best predicted TG (r = 0.46, p < 0.001), whereas insulin sensitivity using the homeostatic model assessment (HOMA %S) correlated best with the HDL‐C (r =0.34, p < 0.001). Higher preoperative fasting glucose best predicted the decrease in TG; improved HOMA %S with weight loss correlated best with HDL‐C. The extent of weight loss had limited influence on lipid changes. However, low preoperative HOMA %S was associated with lower weight loss. Greater weight loss was associated with more favorable lipid measures after controlling for preoperative HOMA %S.

Discussion: Dyslipidemia of obesity is related to weight distribution, insulin sensitivity, and impaired glucose tolerance. Improvement with weight loss is related to the decrease in fasting glucose, improvement in insulin sensitivity, and the extent of weight lost. Improvement in dyslipidemia is sustained with long‐term weight loss.
Human Leptin Stimulates Systemic Nitric Oxide Production in the Rat
Authors: Beltowski Jerzy , Wójcicka Grażyna , Borkowska Ewa
Published: April 2008

Objective:Apart from having an effect on energy balance, leptin is also involved in cardiovascular regulation and in the pathogenesis of obesity‐associated hypertension. We investigated the effect of leptin on nitric oxide (NO) production.

Research Methods and Procedures:Wistar rats were placed in metabolic cages, and urine was collected in 2‐hour periods. After the control period, leptin (1 mg/kg intraperitoneal) was administered, and urine collection was continued for up to 6 hours. Blood was obtained 0.5, 1, 2, 4, and 6 hours after hormone injection.

Results:Leptin increased plasma concentrations of NO metabolites (nitrates + nitrites, NOx) by 32.5%, 58.0%, and 29.7% at 1, 2, and 4 hours, respectively. Urinary NOxexcretion increased by 28.8% in the first and by 20.1% in the second 2‐hour period after injection. The plasma concentration of the NO second messenger, cyclic guanosine 3′,5′‐monophosphate (cGMP), increased by 83% and 50.6% at 2 and 4 hours after leptin administration, respectively. Urinary excretion of cyclic GMP increased by 36.1% in the first and by 43.1% in the second 2‐hour period. Leptin had no effect on the plasma concentration of atrial natriuretic peptide (ANP). The effect of leptin on plasma and urinary NOxwas abolished by the NO synthase inhibitor,NG‐nitro‐l‐arginine methyl ester (l‐NAME) (30 mg/kg intraperitoneal) administered 15 minutes before leptin injection.l‐NAME alone caused a 32.2% increase in systolic blood pressure, but this increase was not observed in rats receivingl‐NAME and leptin.

Discussion:The results indicate that leptin stimulates systemic NO production; leptin prevents blood pressure elevation induced by acute NO blockade, suggesting that leptin also triggers additional hypotensive mechanisms; and ANP is not involved in renal and vascular effects of leptin.
Dietary Weight Loss Decreases Serum Angiotensin‐Converting Enzyme Activity in Obese Adults
Authors: Harp Joyce B. , Henry Steven A. , DiGirolamo Mario
Published: April 2008

Objective: To study the effect of dietary weight loss, postural change, and an oral glucose load on serum angiotensin‐converting enzyme (ACE) activity in obese adults.

Research Methods and Procedures: Sixteen obese adult men and women with a mean body mass index of 35.7 ± 4.3 kg/m2 were studied after 1 week on a maintenance energy lead‐in diet and after 5 weeks on an identical but 40% reduced‐energy diet provided by the General Clinical Research Center (GCRC). ACE activity was measured spectrophotometrically. Plasma renin activity and serum aldosterone were measured by radioimmunoassay.

Results: All subjects lost weight, with a mean decrease in body weight of 7.0 ± 2.1 kg or 6 ± 3% of initial body weight (p < 0.00001). Systolic and diastolic blood pressure, supine plasma renin activity, and serum aldosterone levels decreased with weight loss (p < 0.05). Supine ACE activity decreased 23 ± 12% with weight loss (p < 0.00001). Standing ACE activity, which was significantly higher than supine ACE activity before and after weight loss (p < 0.05), also decreased 18 ± 17% with weight loss (p = 0.0007). A 75‐g oral glucose load had no effect on serum ACE activity over a 3‐hour period.

Discussion: In obese adults, serum ACE activity declines with modest weight loss, increases with postural change, and is unaffected by an oral glucose load.
Hypophysectomy Prevents Ghrelin‐Induced Adiposity and Increases Gastric Ghrelin Secretion in Rats
Authors: Tschöp Matthias , Flora David B. , Mayer John P. , Heiman Mark L.
Published: April 2008

Objective: The novel gastric hormone ghrelin has recently been identified as an important modulator of energy homeostasis. Leptin‐responsive hypothalamic neuropeptide Y/Agouti‐related protein neurons are believed to mediate afferent ghrelin signals. Little is known, however, about ghrelin‐induced efferent signals. We therefore investigated if hypothalamic‐pituitary axes have a role in transferring ghrelin‐induced changes of energy balance to the periphery.

Research Methods and Procedures: We subcutaneously injected hypophysectomized, as well as adrenalectomized, thyroidectomized, and sham‐operated control rats with GH secretagogues [ghrelin, growth hormone (GH)‐releasing peptide] for 1 week. Body weight, food intake, and body composition (chemical carcass analysis) were analyzed and compared with vehicle‐treated controls. In addition, we quantified circulating levels of endogenous ghrelin in hypophysectomized and GH–treated normal rats.

Results: GH‐secretagogue treatment of sham‐operated control rats dose‐proportionally increased food intake, body weight, and fat mass compared with vehicle‐injected controls (p < 0.01). These effects, however, were not observed in ghrelin‐treated hypophysectomized, thyroidectomized, or adrenalectomized rats, indicating an essential role for the pituitary axis in ghrelin‐induced adiposity. Circulating levels of endogenous ghrelin were reduced by administration of GH in normal rats and were about 3‐fold higher in hypophysectomized rats (n = 20, p = 0.001), suggesting a regulatory feedback loop involving the stomach and the pituitary to regulate gastric ghrelin secretion.

Discussion: According to these results, the endocrine pituitary is mediating ghrelin‐induced changes toward a positive energy balance and is involved in the regulation of ghrelin secretion through a gastro‐hypophyseal feedback loop.
Binge Size Increases with Body Mass Index in Women with Binge‐Eating Disorder
Authors: Guss Janet L. , Kissileff Harry R. , Devlin Michael J. , Zimmerli Ellen , Walsh B. Timothy
Published: April 2008

Objective: To determine whether meal size is related to body mass index (BMI) in obese subjects with binge‐eating disorder (BED).

Research Methods and Procedures: Five groups of subjects each consumed two laboratory‐test meals on nonconsecutive days. Forty‐two women, categorized by BMI and BED diagnosis, were instructed to “binge” during one meal and to eat “normally” during another. Eighteen women had BMI values >38 kg/m2 (more‐obese) and 17 had BMI values between 28 to 32 kg/m2 (less‐obese). Twelve of the more‐obese and nine of the less‐obese individuals met Diagnostic and Statistical Manual (DSM)‐IV criteria for BED. Seven normal‐weight women also participated as controls.

Results: Subjects with BED ate significantly more in both meals than subjects without BED. Binge meals were significantly larger than normal meals only among subjects with BED. The more‐obese subjects with BED ate significantly more than the less‐obese subjects with BED, but only when they were asked to binge. Intake of the binge meal was significantly, positively correlated with BMI among subjects with BED. Subjects with BED reported significantly higher satiety ratings after the binge than after the normal meal, but subjects without BED reported similar ratings after both meals. Regardless of instructions and diagnosis, obese subjects consumed a significantly higher percentage of energy from fat (38.5%) than did normal‐weight subjects (30.8%).

Discussion: During binge meals, the energy intake of subjects with BED is greater than that of individuals of similar body weight without BED and is positively correlated with BMI.
Obesity in South Africa: The South African Demographic and Health Survey
Authors: Puoane Thandi , Steyn Krisela , Bradshaw Debbie , Laubscher Ria , Fourie Jean , Lambert Vicki , Mbananga Nolwazi
Published: April 2008

Objectives: To ascertain the anthropometric profile and determinants of obesity in South Africans who participated in the Demographic and Health Survey in 1998.

Research Methods and Procedures: A sample of 13,089 men and women (age, ≥15 years) were randomly selected and then stratified by province and urban and nonurban areas. Height, weight, mid‐upper arm circumference, and waist and hip circumference were measured. Body mass index (BMI) was used as an indicator of obesity, and the waist/hip ratio (WHR) was used as an indicator of abdominal obesity. Multivariate regression identified sociodemographic predictors of BMI and waist circumference in the data.

Results: Mean BMI values for men and women were 22.9 kg/m2 and 27.1 kg/m2, respectively. For men, 29.2% were overweight or obese (≥25 kg/m2) and 9.2% had abdominal obesity (WHR ≥1.0), whereas 56.6% of women were overweight or obese and 42% had abdominal obesity (WHR >0.85). Underweight (BMI <18.5 kg/m2) was found in 12.2% of men and 5.6% of women. For men, 19% of the variation of BMI and 34% of the variation in waist circumference could be explained by age, level of education, population group, and area of residence. For women, these variables explained 16% of the variation of BMI and 24% of the variation in waist circumference. Obesity increased with age, and higher levels of obesity were found in urban African women.

Discussion: Overnutrition is prevalent among adult South Africans, particularly women. Determinants of overnutrition include age, level of education, ethnicity, and area of residence.
Congenic BB.SHR (D4Mit6‐Npy‐Spr) Rats: A New Aid to Dissect the Genetics of Obesity
Authors: Klöting Ingrid , Kovacs Peter , van den Brandt Jens
Published: April 2008

Objective: The phenotypic characterization of congenic BB.LL rats recombining a segment of the SHR chromosome 4 (D4Mit6‐Npy‐Spr; 12 cM) into the BB/OK background indicated that these rats were not lymphopenic and did not develop diabetes, but they were significantly heavier (at 16 weeks of age) and showed higher serum triglycerides and total cholesterol concentration.

Research Methods and Procedures: BB.LL rats were longitudinally studied for facets of metabolic syndrome (body mass index, blood glucose, serum lipids, insulin, leptin, and systolic and diastolic blood pressure) from 2 to 12 months of age.

Results: In this study, it was shown that BB.LL are obese, hyperleptinemic, hyperinsulinemic, and dyslipidemic compared with their parental BB/OK rats.

Discussion: It can be concluded that there is a gene(s) in the introgressed segment causing incomplete metabolic syndrome, because they do not develop hypertension and diabetes. To identify the gene(s), the introgressed chromosomal segment must be systematically whittled down to generate recombinants and new subcongenic lines carrying a much smaller segment of the SHR/Mol rat to increase the chance of identification of the appropriate gene(s).
Amylin, Food Intake, and Obesity
Authors: Reda Tarek K. , Geliebter Allan , Pi‐Sunyer F. Xavier
Published: April 2008

Amylin, also known as islet amyloid polypeptide, identified in 1987, is a naturally occurring hormone, released by the β cells of the pancreas and consists of 37 amino acids. Amylin seems to decrease food intake through both central and peripheral mechanisms and indirectly by slowing gastric emptying. The mean basal amylin concentration is higher in obese than in lean human subjects. The amylin response to oral glucose is also greater in obese subjects, whether or not they have impaired glucose tolerance. The elevated amylin levels in obesity may lead to down‐regulation of amylin receptors and lessen the impact of postprandial amylin secretion on satiety and gastric emptying. Amylin administration may overcome resistance at target tissues, delay gastric emptying, and have potential for inducing weight loss in obese individuals.
Vision and Eating Behavior
Authors: Linné Yvonne , Barkeling Britta , Rössner Stephan , Rooth Pål
Published: April 2008

Objective: Eating behavior is influenced by internal and external factors. Vision is one part of the complex pattern of factors influencing the amount of food consumed during a meal. The aim of this study was to explore the impact of vision on the microstructure of eating behavior and the subjective motivation to eat.

Research Methods and Procedures: Nine blind subjects and nine matched seeing control subjects consumed a standardized meal registered by VIKTOR, an eating monitor, measuring the microstructure of the eating behavior. The eating behavior of the control subjects was registered twice, with and without blindfold.

Results: The eating behavior of the blind subjects did not differ from that of seeing control subjects. However, the eating behavior of seeing subjects eating with blindfold demonstrated a clear impact of vision on eating behavior. When blindfolded, subjects ate 22% less food (p < 0.05), had shorter meal durations (p < 0.05), and had less decelerated eating curves (p < 0.05). Despite a smaller amount of food consumed when blindfolded, the reported feeling of fullness was identical to that reported after the larger meal consumed without blindfold.

Discussion: The importance of vision in regulating our eating behavior is further stressed in this study. Eating with a blindfold decreased the intake of food, without making subjects feel less full. Eating blindfolded, therefore, may force subjects to rely more on internal signals. These results might be used as an aid in the development of new treatment strategies for obese subjects.
Quality of Life after Gastric Bypass Surgery: A Cross‐Sectional Study
Authors: Dymek Maureen P. , Le Grange Daniel , Neven Kim , Alverdy John
Published: April 2008

Objective: Numerous reports document significant weight loss after gastric bypass; however, there is little objective data on postsurgical changes in health‐related quality of life (HRQL).

Research Methods and Procedures: This study examined HRQL in four groups of patients: presurgery (T1), several weeks postsurgery (T2), 6 months postsurgery (T3), and 1 year postsurgery (T4). Subjects were given three HRQL measures: the short form 36 (SF‐36), the Impact of Weight on Quality of Life‐Lite Questionnaire (IWQOL‐Lite), and the Bariatric Analysis and Reporting Outcome System (BAROS). Subjects also completed the Beck Depression Inventory (BDI) and the Rosenberg Self‐Esteem Scale (RSE).

Results: There were no significant differences among the groups on demographics or presurgical body mass index. Results showed significant differences between T1 and T2 on several SF‐36 and IWQOL‐Lite subscales, as well as the RSE and BDI. Significant differences were found on all measures between T2 and T3. Significant differences were found on all subscales of the IWQOL‐Lite, but no subscales of the SF‐36, the RSE, or the BDI between T3 and T4.

Discussion: This study is the first to objectively document these differences in several objective measures of HRQL, depression, and self‐esteem after gastric bypass in a large sample. It is notable that many differences are apparent within several weeks after surgery. Furthermore, results indicate that the IWQOL‐Lite may be more sensitive than the SF‐36 to the changes of quality of life that gastric bypass patients report.
Ethnic Comparison of Weight Loss in the Trial of Nonpharmacologic Interventions in the Elderly
Authors: Kumanyika Shiriki K. , Espeland Mark A. , Bahnson Judy L. , Bottom Juliene B. , Charleston Jeanne B. , Folmar Steve , Wilson Alan C. , Whelton Paul K. ,   TONE Cooperative Research Group
Published: April 2008

Objective:To compare weight loss in blacks and whites in the Trial of Nonpharmacologic Interventions in the Elderly (TONE).

Research Methods and Procedures:TONE enrolled 421 overweight white and 164 overweight black adults, 60 to 79 years old, with blood pressure well‐controlled on a single, antihypertensive drug. Drug therapy withdrawal was attempted 3 months after randomization to counseling for weight loss, sodium reduction, both weight loss and sodium reduction, or to usual care, with follow‐up for 15 to 36 months after enrollment. Statistical procedures included repeated measures analysis of covariance and logistic and proportional hazards regression.

Results:In the weight‐loss condition, net weight change (in kilograms) was −2.7 in blacks and −5.9 in whites (p< 0.001; ethnic difference,p= 0.0002) at 6 months and −2.0 (p< 0.05) in blacks and −4.9 (p< 0.001) in whites at the end of follow‐up (ethnic difference,p= 0.007). In weight/sodium, net weight change was −2.1 (p< 0.01) in blacks and −2.8 (p< 0.001) in whites at 6 months, and −1.9 in blacks and −1.7 in whites at the end of follow‐up (p< 0.05; ethnic difference,p> 0.5). Exploratory analyses suggested a more favorable pattern of weight change in blacks than in whites from 6 months onward. There was no ethnic difference in blood pressure outcomes.

Discussion:Whites lost more weight than blacks without, but not with, a concurrent focus on sodium reduction.
Impact of Visceral Fat on Blood Pressure and Insulin Sensitivity in Hypertensive Obese Women
Authors: Faria Alessandra Nunes , Filho Fernando Flexa Ribeiro , Ferreira Sandra Roberta Gouveia , Zanella Maria Teresa
Published: April 2008

Objective: The relationship among body fat distribution, blood pressure, serum leptin levels, and insulin resistance was investigated in hypertensive obese women with central distribution of fat.

Research Methods and Procedures: We studied 74 hypertensive women (age, 49.8 ± 7.5 years; body mass index, 39.1 ± 5.5 kg/m2; waist‐to‐hip ratio, 0.96 ± 0.08). All patients were submitted to 24‐hour blood pressure ambulatory monitoring (24h‐ABPM). Abdominal ultrasonography was used to estimate the amount of visceral fat (VF). Fasting blood samples were obtained for serum leptin and insulin determinations. Insulin resistance was estimated by homeostasis model assessment insulin resistance index (HOMA‐r index).

Results: Sixty‐four percent of the women were postmenopausal, and all patients showed central distribution of fat (waist‐to‐hip ratio > 0.85). The VF correlated with systolic 24h‐ABPM values (r = 0.28, p = 0.01) and with HOMA‐r index (r = 0.27; p = 0.01). VF measurement (7.5 ± 2.3 vs. 5.9 ± 2.2 cm, p < 0.001) and the systolic 24h‐ABPM (133 ± 14.5 vs. 126 ± 9.8 mm Hg, p = 0.04), but not HOMA‐r index, were significantly higher in the postmenopausal group (n = 48) than in the premenopausal group (n = 26). No correlations were observed between blood pressure levels and HOMA‐r index, leptin, or insulin levels. In the multiple regression analysis, visceral fat, but not age, body fat mass, or HOMA‐r index, correlated with the 24h‐ABPM (p = 0.003).

Discussion: In centrally obese hypertensive women, the accumulation of VF, more often after menopause, is associated with higher levels of blood pressure and insulin resistance. The mechanism through which VF contributes to higher blood pressure levels seems to be independent of leptin or insulin levels.
Metabolic Response to a Mixed Meal in Obese and Lean Women from Two South African Populations
Authors: Punyadeera Chamindie , Crowther Nigel J. , van der Merwe Maria‐Terésa , Toman Marketa , Immelman Andrew Ronnie , Schlaphoff Glen P. , Gray Ian Peter
Published: April 2008

Objective: Lower lipid and insulin levels are found during a glucose‐tolerance test in obese black than obese white South African women. Therefore, β‐cell function and lipid metabolism were compared in these populations during a mixed meal.

Research Methods and Procedures: Blood concentrations of glucose, free fatty acids (FFAs), insulin, lipograms, and in vivo FFA oxidation were determined at fasting and for 7 hours after oral administration of a mixed emulsion containing glucose‐casein‐sucrose‐lipid and [1‐13C] palmitic acid in 8 lean black women (LBW), 10 obese black women (OBW), 9 lean white women (LWW), and 10 obese white women (OWW). Subcutaneous and visceral fat mass was assessed by computerized tomography.

Results: Visceral fat area was higher in OWW (152.7 ± 17.0 cm2) than OBW (80.0 ± 6.7 cm2; p < 0.01). In OBW, 30‐minute insulin levels were higher (604.3 ± 117.6 pM) than OWW (311.0 ± 42.9 pM; p < 0.05). Total triglyceride was higher in OWW (706.7 ± 96.0 mM × 7 hours) than OBW (465.7 ± 48.2 mM × 7 hours; p < 0.05) and correlated with visceral fat area (β = 0.38, p = 0.05). Palmitate oxidation was higher in lean than obese women in both ethnic groups and correlated negatively with fat mass (β = −0.58, p < 0.005).

Discussion: The higher 30‐minute insulin response in OBW may reflect a higher insulinotropic effect of FFAs or glucose. The elevated triglyceride level of OWW may be due to their higher visceral fat mass and possibly reduced clearance by adipose tissue.
Pleiotropic Relationships between Cortisol Levels and Adiposity: The HERITAGE Family Study
Authors: Feitosa Mary F. , Rice Treva , Rosmond Roland , Rankinen Tuomo , Leon Arthur S. , Skinner James S. , Wilmore Jack H. , Bouchard Claude , Rao D. C.
Published: April 2008

Objective: To investigate familial basis for the relationship between cortisol adiposity at baseline and their training responses.

Research Methods and Procedures: Bivariate correlation and segregation analyses were employed between cortisol and several adiposity measures [body mass index, fat mass (FM), fat‐free mass, percentage of body fat (% BF), abdominal visceral fat (AVF), abdominal subcutaneous fat (ASF), and abdominal total fat (ATF)] from 99 white families and 105 black families.

Results: In both races, significant inverse phenotypic correlations were generally observed between cortisol and adiposity measures at baseline but not for training responses. Significant cross‐trait familial correlations were found for cortisol with abdominal fat (ASF, AVF, ATF) and overall body adiposity (FM, % BF) measures at baseline, which accounted for 14% to 20% of the phenotypic variance in whites. The cross‐trait correlations were not significant for baseline phenotypes in blacks, perhaps because of the small sample size. A bivariate segregation analysis showed evidence of polygenic pleiotropy for cortisol with both abdominal fat and overall adiposity measures that accounted for 14% to 17% of the phenotypic covariance, but major gene pleiotropy was not suggested in whites. However, when ASF, AVF, and ATF were additionally adjusted for FM, no familial cross‐trait correlations or polygenic pleiotropy between cortisol and the abdominal fat measures remained.

Discussion: Evidence was found for polygenic pleiotropy but not for pleiotropic major gene effects between cortisol and overall adiposity in whites. However, the covariation of cortisol with abdominal fat phenotypes is dependent on concomitant polygenic factors for total‐body fat.