Αρχειοθήκη ιστολογίου

Κυριακή 1 Μαΐου 2016

Reduced-form modeling of public health impacts of inorganic PM2.5 and precursor emissions

Publication date: July 2016
Source:Atmospheric Environment, Volume 137
Author(s): Jinhyok Heo, Peter J. Adams, H. Oliver Gao
It is challenging to estimate the public health costs of fine particulate matter (PM2.5) and its precursor emissions accurately and quickly for policy research because of their complex physical and chemical processes occurring over a large downwind area. We developed a method for building statistical regressions that estimate public health cost of emissions accurately like a state-of-the-art chemical transport model (CTM) but without its high computational cost. This method achieves detailed spatial resolution according to the location of the emission source, accounting for differences in the exposed population downwind. Using tagged CTM simulations, our method builds a large dataset of air quality public health costs from marginal emissions throughout the United States. Two methods were developed to describe exposed population, one that assumes a generic downwind plume concentration profile derived from CTM outputs and a simpler method that uses the size of population within certain distances as variables. Using the former method, we parameterized marginal public health cost [$/t] and intake fraction [ppm] as a function of exposed population and key atmospheric variables. We derived models for elemental carbon, sulfur dioxide, nitrogen oxides, and ammonia. Compared to estimates calculated directly using CTM outputs, our models generally show mean fractional errors of only 10%–30% and up to 50% for NOx in some seasons, which are generally similar to or less than CTM's performance. Our results show that the public health costs of emissions can be efficiently parameterized for policy analyses based on state-of-the-art CTMs.

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Episodic air quality impacts of plug-in electric vehicles

Publication date: July 2016
Source:Atmospheric Environment, Volume 137
Author(s): Ghazal Razeghi, Marc Carreras-Sospedra, Tim Brown, Jack Brouwer, Donald Dabdub, Scott Samuelsen
In this paper, the Spatially and Temporally Resolved Energy and Environment Tool (STREET) is used in conjunction with University of California Irvine – California Institute of Technology (UCI-CIT) atmospheric chemistry and transport model to assess the impact of deploying plug-in electric vehicles and integrating wind energy into the electricity grid on urban air quality. STREET is used to generate emissions profiles associated with transportation and power generation sectors for different future cases. These profiles are then used as inputs to UCI-CIT to assess the impact of each case on urban air quality.The results show an overall improvement in 8-h averaged ozone and 24-h averaged particulate matter concentrations in the South Coast Air Basin (SoCAB) with localized increases in some cases. The most significant reductions occur northeast of the region where baseline concentrations are highest (up to 6 ppb decrease in 8-h-averaged ozone and 6 μg/m3 decrease in 24-h-averaged PM2.5). The results also indicate that, without integration of wind energy into the electricity grid, the temporal vehicle charging profile has very little to no effect on urban air quality. With the addition of wind energy to the grid mix, improvement in air quality is observed while charging at off-peak hours compared to the business as usual scenario.

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A new reconstruction of atmospheric gaseous elemental mercury trend over the last 60 years from Greenland firn records

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Publication date: July 2016
Source:Atmospheric Environment, Volume 136
Author(s): A. Dommergue, P. Martinerie, J. Courteaud, E. Witrant, D.M. Etheridge
This study presents measurements of gaseous elemental mercury (GEM) concentrations in the 80 m of firn air at the international drilling site of NEEM in Greenland (2452 m, 77°25.8 N, 51°06.4 W). Using inverse modeling, we were able to reconstruct the atmospheric GEM trend at this Arctic site over the last 60 years. We show discrepancies between this record and the previous firn record of Summit. This could be attributed to experimental biases and/or differences in air mass transport. A multisite inverse model was used to derive an atmospheric scenario reconciling the two firn records. We show that GEM seasonal variations are very limited at these high altitude sites and thus probably unaffected by spring/summer photochemistry. The firn reconstructions suggest an increase of GEM concentrations since the 1950s peaking in the late 1960s and early 1970s. A decrease is then observed with minimum GEM concentrations around 1995–2000. The reconstruction compares well with historical mercury (Hg) releases and recent simulations of atmospheric Hg. Our optimal GEM scenario does not allow to categorically conclude on recent trends for GEM concentrations over the 2000–2010 decade.



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Targeted silencing of survivin in cancer cells by siRNA loaded chitosan magnetic nanoparticles.

Targeted silencing of survivin in cancer cells by siRNA loaded chitosan magnetic nanoparticles.

Expert Rev Anticancer Ther. 2016 Apr 29;

Authors: Unsoy G, Gunduz U

Abstract
OBJECTIVE: The aim of this study was to silence Survivin expression, related with drug-resistance, via siRNA-loaded CS-MNPs.
METHODS AND RESULTS: The highest siRNA-loading efficiency was achieved at siRNA:CS-MNP ratio of 1:2. Nanoparticles had spherical morphology and homogenous size distribution in TEM. After siRNA loading, core sizes (3-5nm) of CS-MNPs didn't change significantly, however hydrodynamic diameters increased ~10nm, indicating swelling of chitosan coat due to efficient siRNA loading. 73% of siRNA was pH-dependently released at 24hrs, after 30% burst release at first 3.5hrs. Stability was high enough to keep siRNAs in CS-MNPs at pH7.2. Cellular-internalization of Survivin-siRNA-CS-MNPs was high and localized in cytoplasm of cells.
CONCLUSION: Although, mock-siRNA loaded/unloaded CS-MNPs weren't cytotoxic, cell-death of breast cancer cells was significantly increased, after the treatment of Survivin-siRNA-loaded CS-MNPs. This reveals, successful loading of Survivin-siRNA on CS-MNPs and significant silencing of Survivin expression by triggering cell-death. Consequently, CS-MNPs are highly efficient delivery systems for intact siRNAs.

PMID: 27130312 [PubMed - as supplied by publisher]



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Role of Vitamin K Antagonists in the Prevention of Thrombotic Bypass Occlusion After Infrainguinal Venous Bypass

Publication date: Available online 30 April 2016
Source:European Journal of Vascular and Endovascular Surgery
Author(s): E. Gándara, D. Hammond, S. Nagpal
Clinical vignetteDespite being the most common antithrombotic strategy in trials comparing venous with prosthetic grafts, the use of vitamin K antagonists (VKAs) to improve the outcome of venous bypass remains the subject of debate. In this systematic review, evidence supporting the use of VKAs for improving venous patency following infrainguinal venous bypass is provided.Clinical questionA 67 year old man with lifestyle limiting claudication underwent a successful infrainguinal venous bypass. Can VKAs help preserve patency after venous bypass surgery?MethodsA systematic review of electronic databases, including MEDLINE and Embase, was conducted. Only randomized controlled studies comparing VKAs with aspirin (ASA) were included. The main outcome was bypass patency.ResultsFour studies using different intensities of anticoagulation ± ASA were identified. All but one showed a benefit of VKAs over ASA with respect to primary patency. However, this benefit was also accompanied by an increased risk of bleeding. The Dutch Bypass Oral Anticoagulants, or ASA, study was the largest included and showed that VKAs (without concomitant ASA) were superior to ASA alone for the prevention of graft occlusion (hazard ratio 0.69, 95% confidence interval 0.54–0.88).ConclusionCurrent evidence suggests that VKAs are superior to ASA for the prevention of infrainguinal autologous venous graft thrombosis.



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Self-referral to the NHS Abdominal Aortic Aneurysm Screening Programme

Publication date: Available online 30 April 2016
Source:European Journal of Vascular and Endovascular Surgery
Author(s): L. Meecham, J. Jacomelli, A.D. Pherwani, J. Earnshaw
IntroductionThe NHS Abdominal Aortic Screening Programme (NAAASP) invites men in their 65th year for screening, men over 65 may self-refer into the programme. Most studies have concentrated on those invited for screening, little is known about the self-referral group. Our aim was to provide a descriptive analysis of the men who self refer to NAAASP for screening.MethodInformation concerning basic demographic details and ultrasound results were recorded on the AAA SMaRT database. During nurse assessment data collected included smoking status, blood pressure, height, weight, and aspirin and statin therapy. Statistical analysis was performed using SPSS®20.ResultsA total of 58,999 men have self-referred to the NAAASP since its inception. The mean age at self-referral was 73 (47–100). The mean aortic diameter was 1.9 cm (0.8–12.1). Increased self-referral rates were observed following organised publicity. The incidence of AAA was 4.1% (n = 2438) compared with 1.4% in the invited cohort (age 65 years), of these 7.6% (n = 186) were >5.5 cm. Of the 186, 152 (81.7%) underwent surgery, of which 55.3% (n = 84) underwent EVAR. The 30-day mortality in the men treated electively was 0%. The mean time from referral to surgery was 69 (2–361) days, with 57.9% (n = 88) being treated within 8 weeks of detection.ConclusionSelf-referral has yielded higher detection rates than the invited cohort, more than justifying its cost. Now that NAAASP is fully operational it is important to continue media campaigns and publicity to target the "at-risk" men over 65 who would otherwise miss the benefits of AAA screening. Some key areas still need to be addressed.



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Prolyl hydroxylase-1 regulates hepatocyte apoptosis in an NF-κB-dependent manner.

Prolyl hydroxylase-1 regulates hepatocyte apoptosis in an NF-κB-dependent manner.

Biochem Biophys Res Commun. 2016 Apr 26;

Authors: Fitzpatrick SF, Fábián Z, Schaible B, Lenihan CR, Schwarzl T, Rodriguez J, Zheng X, Li Z, Tambuwala MM, Higgins DG, O'Meara Y, Slattery C, Manresa MC, Fraisl P, Bruning U, Baes M, Carmeliet P, Doherty G, von Kriegsheim A, Cummins EP, Taylor CT

Abstract
Hepatocyte death is an important contributing factor in a number of diseases of the liver. PHD1 confers hypoxic sensitivity upon transcription factors including the hypoxia inducible factor (HIF) and nuclear factor-kappaB (NF-κB). Reduced PHD1 activity is linked to decreased apoptosis. Here, we investigated the underlying mechanism(s) in hepatocytes. Basal NF-κB activity was elevated in PHD1(-/-) hepatocytes compared to wild type controls. ChIP-seq analysis confirmed enhanced binding of NF-κB to chromatin in regions proximal to the promoters of genes involved in the regulation of apoptosis. Inhibition of NF-κB (but not knock-out of HIF-1 or HIF-2) reversed the anti-apoptotic effects of pharmacologic hydroxylase inhibition. We hypothesize that PHD1 inhibition leads to altered expression of NF-κB-dependent genes resulting in reduced apoptosis. This study provides new information relating to the possible mechanism of therapeutic action of hydroxylase inhibitors that has been reported in pre-clinical models of intestinal and hepatic disease.

PMID: 27130823 [PubMed - as supplied by publisher]



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