325 research outputs found
General health and residential proximity to the coast in Belgium : results from a cross-sectional health survey
The health risks of coastal areas have long been researched, but the potential benefits for health are only recently being explored. The present study compared the general health of Belgian citizens a) according to the EU's definition of coastal ( 50 km), and b) between eight more refined categories of residential proximity to the coast ( 250 km). Data was drawn from the Belgian Health Interview Survey (n = 60,939) and investigated using linear regression models and mediation analyses on several hypothesized mechanisms. Results indicated that populations living 50-100 km. Four commonly hypothesized mechanisms were considered but no indirect associations were found: scores for mental health, physical activity levels and social contacts were not higher at 0-5 km from the coast, and air pollution (PM ic , concentrations) was lower at 0-5 km from the coast but not statistically associated with better health. Results are controlled for typical variables such as age, sex, income, neighbourhood levels of green and freshwater blue space, etc. The spatial urban-rural-nature mosaic at the Belgian coast and alternative explanations are discussed. The positive associations between the ocean and human health observed in this study encourage policy makers to manage coastal areas sustainably to maintain associated public health benefits into the future
Interactions between docetaxel (Taxotere) and Plasmodium falciparum-infected erythrocytes.
Experimental validation of an analytical model for nonlinear propagation in uncompensated optical links
Antiplasmodial Activity of Nitroaromatic Compounds : Correlation with Their Reduction Potential and Inhibitory Action on Plasmodium falciparum Glutathione Reductase
With the aim to clarify the mechanism(s) of action of nitroaromatic compounds against the malaria parasite Plasmodium falciparum, we examined the single-electron reduction by P. falciparum ferredoxin:NADP+ oxidoreductase (PfFNR) of a series of nitrofurans and nitrobenzenes (n = 23), and their ability to inhibit P. falciparum glutathione reductase (PfGR). The reactivity of nitroaromatics in PfFNR-catalyzed reactions increased with their single-electron reduction midpoint potential (E17). Nitroaromatic compounds acted as non- or uncompetitive inhibitors towards PfGR with respect to NADPH and glutathione substrates. Using multiparameter regression analysis, we found that the in vitro activity of these compounds against P. falciparum strain FcB1 increased with their E17 values, octanol/water distribution coefficients at pH 7.0 (log D), and their activity as PfGR inhibitors. Our data demonstrate that both factors, the ease of reductive activation and the inhibition of PfGR, are important in the antiplasmodial in vitro activity of nitroaromatics. To the best of our knowledge, this is the first quantitative demonstration of this kind of relationship. No correlation between antiplasmodial activity and ability to inhibit human erythrocyte GR was detected in tested nitroaromatics. Our data suggest that the efficacy of prooxidant antiparasitic agents may be achieved through their combined action, namely inhibition of antioxidant NADPH:disulfide reductases, and the rapid reduction by single-electron transferring dehydrogenases-electrontransferases
Health benefits of physical activity related to an urban riverside regeneration
The promotion of physical activity through better urban design is one pathway by which health and well-being improvements can be achieved. This study aimed to quantify health and health-related economic impacts associated with physical activity in an urban riverside park regeneration project in Barcelona, Spain. We used data from Barcelona local authorities and meta-analysis assessing physical activity and health outcomes to develop and apply the “Blue Active Tool”. We estimated park user health impacts in terms of all-cause mortality, morbidity (ischemic heart disease; ischemic stroke; type 2 diabetes; cancers of the colon and breast; and dementia), disability-adjusted life years (DALYs) and health-related economic impacts. We estimated that 5753 adult users visited the riverside park daily and performed different types of physical activity (walking for leisure or to/from work, cycling, and running). Related to the physical activity conducted on the riverside park, we estimated an annual reduction of 7.3 deaths (95% CI: 5.4; 10.2), and 6.2 cases of diseases (95% CI: 2.0; 11.6). This corresponds to 11.9 DALYs (95% CI: 3.4; 20.5) and an annual health-economic impact of 23.4 million euros (95% CI: 17.2 million; 32.8 million). The urban regeneration intervention of this riverside park provides health and health-related economic benefits to the population using the infrastructure
Halogen chemistry in volcanic plumes: a 1D framework based on MOCAGE 1D (version R1.18.1) preparing 3D global chemistry modelling
HBr emissions from volcanoes lead rapidly to the formation of BrO within volcanic plumes and have an impact on tropospheric chemistry, at least at the local and regional scales. The motivation of this paper is to prepare a framework for further 3D modelling of volcanic halogen emissions in order to determine their fate within the volcanic plume and then in the atmosphere at the regional and global scales. The main aim is to evaluate the ability of the model to produce a realistic partitioning of bromine species within a grid box size typical of MOCAGE (Model Of atmospheric Chemistry At larGE scale) 3D (0.5×0.5). This work is based on a 1D single-column configuration of the global chemistry-transport model MOCAGE that has low enough computational cost to allow us to perform a large set of sensitivity simulations. This paper uses the emissions from the Mount Etna eruption on 10 May 2008. Several reactions are added to MOCAGE to represent the volcanic plume halogen chemistry. A simple plume parameterisation is also implemented and tested. The use of this parameterisation tends to only slightly limit the efficiency of BrO net production. Both simulations with and without the parameterisation give results for the partitioning of the bromine species, of ozone depletion and of the BrO/SO2 ratio that are consistent with previous studies. A series of test experiments were performed to evaluate the sensitivity of the results to the composition of the emissions (primary sulfate aerosols, Br radical and NO) and to the effective radius assumed for the volcanic sulfate aerosols. Simulations show that the plume chemistry is sensitive to all these parameters. We also find that the maximum altitude of the eruption changes the BrO production, which is linked to the vertical variability of the concentrations of oxidants in the background air. These sensitivity tests display changes in the bromine chemistry cycles that are generally at least as important as the plume parameterisation. Overall, the version of the MOCAGE chemistry developed for this study is suitable to produce the expected halogen chemistry in volcanic plumes during daytime and night-time
Photochemical oxidative addition of germane and diphenylgermane to ruthenium dihydride complexes
Photochemical reactions of germane and diphenylgermane with Ru(PP) 2 H 2 (PP = R 2 PCH 2 CH 2 PR 2 or DuPhos, R = Ph dppe, R = Et depe, R = Me dmpe) are reported. Reaction with GeH 4 generates a mixture of cis and trans isomers of Ru(PP) 2 (GeH 3 )H except for the DuPhos complex which yields the product only in the cis form. In situ laser photolysis (355 nm) demonstrates that the initial product is the cis isomer that undergoes thermal isomerization to the trans isomer. The complex cis-[Ru(dppe) 2 (GeH 3 )H] crystallizes selectively, allowing determination of its X-ray structure as a germyl hydride with a long Ru-H···Ge separation of 2.64(3) Å indicating that no residual interaction between the RuH and Ge is present. DFT calculations are also consistent with full oxidative addition. The structure of cis-[Ru(DuPhos) 2 (GeH 3 )H] reveals significant distortion from an octahedral geometry. The major species in the crystal (95%) exhibits a structure with a Ru-H···Ge distance of 2.42(5) Å suggesting negligible interaction between these centers. DFT calculations of the structure are consistent with the experimental determination. The reactions of Ru(PP) 2 H 2 with diphenylgermane yield cis-[Ru(PP) 2 (GePh 2 H)H] exclusively for PP = dmpe and depe, while the cis isomer is dominant in the case of dppe. A photochemical competition reaction between Ru(dppe) 2 (H) 2 and the two substrates Ph 2 SiH 2 and Ph 2 GeH 2 results in both Si-H and Ge-H oxidative addition activation with a kinetic preference (0.18:1) for the germyl hydride product. Thermal conversion of Ru(dppe) 2 (SiPh 2 H)H to Ru(dppe) 2 (GePh 2 H)H is observed on heating
Antimalarial xanthones from Calophyllum caledonicum and Garcinia vieillardii
The antimalarial activity of 22 xanthones against chloroquino-resistant strains of Plasmodium falciparum was evaluated. Natural caloxanthone C, demethylcalabaxanthone, calothwaitesixanthone, calozeyloxanthone, dombakinaxanthone, macluraxanthone, and 6-deoxy-γ-mangostin were isolated from Calophyllum caledonicum. 1,6-dihydroxyxanthone, pancixanthone A, isocudraniaxanthone B, isocudraniaxanthone A, 2-deprenylrheediaxanthone B and 1,4,5-trihydroxyxanthone were isolated from Garcinia vieillardii. Moreover, synthetic compounds are analogues or intermediates of xanthones purified from Calophyllum caledonicum (Oger J.M., Morel C., Hélesbeux J.J., Litaudon M., Séraphin D., Dartiguelongue C., Larcher G., Richomme P., Duval O. 2003. First 2-Hydroxy-3-Methylbut-3-Enyl substituted xanthones isolated from Plants: structure elucidation, synthesis and antifungal activity. Natural Product Research 17(3), 195–199; Hélesbeux J.J., Duval O., Dartiguelongue C., Séraphin D., Oger J.M., Richomme P., 2004. Synthesis of 2-hydroxy-3-methylbut-3-enyl substituted coumarins and xanthones as natural products. Application of the Schenck ene reaction of singlet oxygen with ortho-prenylphenol precursors. Tetrahedron 60(10), 2293–2300). The relationship between antimalarial activity and molecular structure of xanthones has also been explored. The most potent xanthones and (IC50 = c.a. 1.0 μg/mL) are 1,3,7 trioxygenated and prenylated on the positions 2 and 8
Preparative Isolation, Fast Centrifugal Partition Chromatography Purification and Biological Activity of Cajaflavanone from Derris ferruginea Stems
Introduction
The Derris genus is known to contain flavonoid derivatives, including prenylated flavanones and isoflavonoids such as rotenoids, which are generally associated with significant biological activity.
Objective
To develop an efficient preparative isolation procedure for bioactive cajaflavanone.
Methodology
Fast centrifugal partition chromatography (FCPC) was optimised to purify cajaflavanone from Derris ferruginea stems in a single step as compared to fractionation from the cyclohexane extract by successive conventional solid–liquid chromatography procedures. The purification yield, purity, time and solvent consumption per procedure are described. The anti-fungal, anti-bacterial, anti-leishmanial, anti-plasmodial, anti-oxidant activities and the inhibition of advanced glycation end-products (AGEs) by cajaflavanone accumulation are described.
Results
FCPC enabled cajaflavanone purification in a single separation step, yielding sufficient quantities to perform in vitro biological screening. Interestingly, cajaflavanone had an inhibitory effect on the formation of AGEs, without displaying any in vitro anti-oxidant activity.
Conclusion
A simple and efficient procedure, in comparison with other preparative methods, for bioactive cajaflavone purification has been developed using FCPC
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