Cerebral activations during viewing of food stimuli in adult patients with acquired structural hypothalamic damage: A functional neuroimaging study

BACKGROUND/OBJECTIVES: Obesity is common following hypothalamic damage due to tumours. Homeostatic and non-homeostatic brain centres control appetite and energy balance but their interaction in the presence of hypothalamic damage remains unknown. We hypothesized that abnormal appetite in obese patients with hypothalamic damage results from aberrant brain processing of food stimuli. We sought to establish differences in activation of brain food motivation and reward neurocircuitry in patients with hypothalamic obesity (HO) compared with patients with hypothalamic damage whose weight had remained stable. SUBJECTS/METHODS: In a cross-sectional study at a University Clinical Research Centre, we studied 9 patients with HO, 10 age-matched obese controls, 7 patients who remained weight-stable following hypothalamic insult (HWS) and 10 non-obese controls. Functional magnetic resonance imaging was performed in the fasted state, 1 h and 3 h after a test meal, while subjects were presented with images of high-calorie foods, low-calorie foods and non-food objects. Insulin, glucagon-like peptide-1, Peptide YY and ghrelin were measured throughout the experiment, and appetite ratings were recorded. RESULTS: Mean neural activation in the posterior insula and lingual gyrus (brain areas linked to food motivation and reward value of food) in HWS were significantly lower than in the other three groups (P=0.001). A significant negative correlation was found between insulin levels and posterior insula activation (P=0.002). CONCLUSIONS: Neural pathways associated with food motivation and reward-related behaviour, and the influence of insulin on their activation may be involved in the pathophysiology of HO.International Journal of Obesity advance online publicatio

SnoRNA Snord116 (Pwcr1/MBII-85) Deletion Causes Growth Deficiency and Hyperphagia in Mice

Prader-Willi syndrome (PWS) is the leading genetic cause of obesity. After initial severe hypotonia, PWS children become hyperphagic and morbidly obese, if intake is not restricted. Short stature with abnormal growth hormone secretion, hypogonadism, cognitive impairment, anxiety and behavior problems are other features. PWS is caused by lack of expression of imprinted genes in a ∼4 mb region of chromosome band 15q11.2. Our previous translocation studies predicted a major role for the C/D box small nucleolar RNA cluster SNORD116 (PWCR1/HBII-85) in PWS. To test this hypothesis, we created a ∼150 kb deletion of the >40 copies of Snord116 (Pwcr1/MBII-85) in C57BL/6 mice. Snord116del mice with paternally derived deletion lack expression of this snoRNA. They have early-onset postnatal growth deficiency, but normal fertility and lifespan. While pituitary structure and somatotrophs are normal, liver Igf1 mRNA is decreased. In cognitive and behavior tests, Snord116del mice are deficient in motor learning and have increased anxiety. Around three months of age, they develop hyperphagia, but stay lean on regular and high-fat diet. On reduced caloric intake, Snord116del mice maintain their weight better than wild-type littermates, excluding increased energy requirement as a cause of hyperphagia. Normal compensatory feeding after fasting, and ability to maintain body temperature in the cold indicate normal energy homeostasis regulation. Metabolic chamber studies reveal that Snord116del mice maintain energy homeostasis by altered fuel usage. Prolonged mealtime and increased circulating ghrelin indicate a defect in meal termination mechanism. Snord116del mice, the first snoRNA deletion animal model, reveal a novel role for a non-coding RNA in growth and feeding regulation

Particulate dry deposition and overall deposition velocities of polycyclic aromatic hydrocarbons

Previous studies have shown that the dry deposition of semivolatile organic compounds to the Great Lakes can account for a significant fraction of their total inputs. However, there is no generally accepted method to directly measure dry deposition. In this study the particulate dry deposition of polycyclic aromatic hydrocarbons (PAHs) was measured using smooth surrogate surfaces during the winter of 1996-1997 in Chicago. Concurrently, ambient air samples were collected. Average particulate Sigma(13)-PAH fluxes and ambient concentrations were 120 +/- 28 mug/m(2) d and 30 +/- 16 ng/m(3), respectively. The measured particulate dry deposition fluxes were similar to those measured in other urban areas. Overall dry deposition velocities of PAHs calculated using the dry deposition fluxes and ambient concentrations averaged 4.5 +/- 3.1 cm/s. This value is higher than values typically used to estimate PAH particulate deposition, however, it agrees well with values determined using similar techniques. The overall dry deposition velocity for individual PAHs generally decreased with increasing molecular weight. This finding is consistent with the previous experimental studies that have shown that a greater fraction of the higher molecular weight PAHs are associated with fine articles relative to the lower molecular weight compounds

Dry deposition measured with a water surface sampler: a comparison to modeled results

In this study, a water surface sampler (WSS) and a knife-leading-edge surrogate surface (KSS) covered with both a Nylasorb filter, and a greased strip were used to directly measure nitrate, sulfate, and ammonium dry fluxes in Chicago between May and October 1997. Concurrently, an annular denuder system was used to measure the ambient concentration of gaseous nitric acid, sulfur dioxide, and ammonia gases. Water evaporation and relative humidity were also simultaneously measured. The measured fluxes and ambient concentrations were used to calculate the mass transfer coefficients of all four species

Measurement of the vapor phase deposition of polychlorinated bipheyls (PCBs) using a water surface sampler

A water surface sampler (WSS) was employed in combination with greased knife-edge surface deposition plates (KSSs) to measure the vapor phase deposition rates of PCBs to the sampler at an urban site, Chicago, IL. This sampler employed a water circulation system that continuously removed deposited PCBs. Total (gas + particle) and particulate PCB fluxes were collected with the WSS and KSSs, respectively. Gas phase PCB fluxes were then calculated by subtracting the KSS fluxes (particulate) from the WSS fluxes (gas + particle). The calculated gas phase PCB fluxes averaged 830 +/- 910 ng m(-2) d(-1). This flux value is, in general, higher than the fluxes determined using simultaneously measured air-water concentrations in natural waters and is in the absorption direction. This difference is primarily because the PCBs were continuously removed from the WSS water keeping the water PCB concentration near zero

Concentrations and gas/particle partitioning of PCBs in Chicago

Thirty seven air samples were collected in Chicago, IL from June to October 1995 and analyzed for gas and particle concentrations of polychlorinated biphenyls (PCBs). Lower molecular weight (MW) PCBs dominated the samples and on average 95% of the Sigma(50)PCB concentration (gas + particulate) was in the vapor phase. Sigma(50)PCB concentrations were classified based on prevailing winds (lake and land). The Sigma(50)PCB concentration varied between 0.42 and 5.21 ng/m(3) (1.80 +/- 1.70 ng/m(3)) for lake and 0.53 and 8.31 ng/m(3) (2.41 +/- 2.15 ng/m(3)) for land wind directions. Back trajectory analyses suggested that SW of Chicago can be an important local or regional source sector for PCBs. Partitioning between gas and particulate phases was modeled using the Junge-Pankow model. The measured particle phase concentrations for low MW PCBs were lower than those predicted by the model while the opposite was observed for high MW PCBs. Plots of gas/particle partition coefficient (log K-p) vs. subcooled liquid vapor pressure (log p(L)(0) had reasonable correlations for individual samples but the slope varied among the samples. Samples that originated from over the lake had higher slopes than samples that originated from over the land. (C) 2004 Elsevier Ltd. All rights reserved

Measurement of dry deposition and air-water exchange of polycyclic aromatic hydrocarbons with the water surface sampler

Recent work has shown that dry deposition and gas exchange of semivolatile organic compounds in the Great Lakes is important. However, there is no generally accepted method for collecting particulate dry deposition or gas exchange. in this work the Water Surface Sampler (WSS) was modified and used in combination with dry deposition plates to measure the particulate dry deposition and gas exchange of PAHs. Simultaneous dry deposition and ambient air samples were collected between June and October 1995 in Chicago, II. Total (particulate + gas) fluxes were measured with the WSS, while particulate fluxes were measured with dry deposition plates. Average Sigma(14)-PAH and particulate Sigma(14)-PAH fluxes were 360 +/- 146 mu g/m(2) d and 144 +/- 60 mu g/m(2) d, respectively. Gas-phase fluxes, determined by subtracting the dry deposition plate fluxes (particulate) from WSS fluxes (particulate + gas), averaged 170 +/- 72 mu g/m(2) d. The measured particulate dry deposition and gas exchange fluxes were substantially higher than those previously reported for the Great Lakes and nonurban areas, probably due to the significantly higher ambient PAH concentrations found in Chicago. Particulate phase overall dry deposition velocities calculated using the dry de position fluxes and ambient concentrations averaged 6.7 +/- 2.8 cm/s. This value is higher than values estimated using dry deposition models; however, it is in good agreement with values determined using similar techniques

Polycyclic aromatic hydrocarbons (PAHs) in Chicago air

Ambient air samples were collected in Chicago, IL between June and October 1995 as part of a study to investigate the dry deposition and air-water exchange of polycyclic aromatic hydrocarbons (PAHs). A modified high-volume sampler (PS-1 sampler) was used to collect airborne PAHs in both the particulate and gas phases. The average total (gas + particulate) Sigma(14)-PAH concentration was 428 +/- 240 ng m(-3), similar to those previously observed in Chicago, IL and other urban areas. The particle/gas phase distribution varied widely. The gas phase percentage ranged from 1.1 to 99.4%, and generally decreased with increasing molecular weight. The amount of PAHs associated with the particulate phase increased with decreasing temperature, probably due to the temperature dependence of gas/particle partitioning. Concentrations of PAHs with molecular weights between 154 and 202 were correlated well with phenanthrene concentrations while compounds with molecular weights higher than 202 had little or no correlation with phenanthrene concentration, probably due to the different partitioning, transport and removal characteristics of low and high molecular weight compounds

Traffic air pollution monitoring based on an air-water pollutants deposition device

An air water surface sampler device was developed and used to evaluate the atmosphere deposition due to the urban traffic air pollution in the business center of a mid-sized city. The indicator adopted to assess the cumulative air pollutant deposition in the surface of the device was the electric conductivity that was measured on a regular basis during the experiment. Additionally a digital camera was used to count the passing traffic in the road of the study site. Water samples were also taken from the device reservoir and dissolved metals concentrations (Cooper, Iron and Zinc) and acidity/alcalinity were determined in the laboratory. The obtained results were compiled and analyzed in order to evaluate the performance of the device and the relation between the atmospheric deposition and the traffic activity under different meteorological conditions. The research successfully proved that the device was able to evaluate the impact of pollutant emissions related to city traffic. It was also proved that electric conductivity can be used as an indicator to evaluate the cumulative deposition of air pollutants from road traffic. A significant correlation (Spearman rank) between the accumulated traffic and electric conductivity (dry period: ϱ= 0.991626 and wet period: ϱ= 0.810526) was observed.The authors gratefully acknowledge to Erasmus Mundus ECW EUROASIA-lot 12 (REF. 2009-1797) for the financial support granted through a scholarship for the Urban Engineering Master Course, to the Territory Environment and Construction Research Centre of University of Minho for the use of laboratory facilities, and to the school staff of the study site for their cooperation during the installation of equipment for this research. The authors gratefully acknowledge to anonymous reviewers for their important contributions to the final version of the paper