7 research outputs found

    Plasma nitrite/nitrate concentrations in patients with schizophrenia

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    Background: Nitric oxide (NO) is known to be a signaling molecule with many physiogical functions including apoptotic process regulation. Since apoptosis may contribute to the pathophysiology of schizophrenia, this study was undertaken to determine the plasma concentrations of NO in schizophrenics. Methods: Nitrite/nitrate (NO2–/NO3–) concentrations were measured in plasma from 40 patients with schizophrenia, and 36 age- and gender-matched healthy persons using a colorimetric test. Results: Plasma NO2–/NO3– concentrations were significantly higher in patients with schizophrenia (102.8±34.7 μmol/L, p<0.0001) than in controls (69.2±13.2 μmol/L). Also, mean NO2–/NO3– values in female patients and controls were significantly higher (118.2±44.7 μmol/L, p<0.001; 74.8±16.1 μmol/L, p<0.05, respectively) compared to males (94.7±25.3 μmol/L, 67.6±10.8 μmol/L). Significant correlation was seen between plasma NO2–/NO3– concentrations and heredity, number of episodes and peripheral blood mononuclear cell (PBMC) caspase-3 activity, which was significantly higher in patients than in controls (p<0.05). There was no significant difference in NO2–/NO3– concentrations between patients with different Positive and Negative Syndrome Scale (PANSS) scores or between patients treated with haloperidol (97.2±31.2 μmol/L) and those treated with other atypical antipsychotic drugs (109.8±33.7 μmol/L). Both parameters showed no significant differences between smokers and non-smokers. Conclusions: This study showed that plasma NO2–/NO3– concentrations were significantly increased in patients with schizophrenia, being significantly higher in female than male patients, and showing a significant correlation with heredity, number of episodes and PBMC caspase-3 activity. These results suggest that NO could be considered an inducer or regulator of apoptosis in patients with schizophrenia. Clin Chem Lab Med 2010;48:89–94.Peer Reviewe

    Global patterns and environmental drivers of forest functional composition

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    Aim: To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location: Global. Time period: Recent. Major taxa studied: Trees. Methods: We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community-weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results: Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within-biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions: Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within-biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.</p

    Global patterns and environmental drivers of forest functional composition

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    Aim: To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location: Global. Time period: Recent. Major taxa studied: Trees. Methods: We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community-weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results: Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within-biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions: Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within-biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.</p

    Global patterns and environmental drivers of forest functional composition

    No full text
    International audienceAim: To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location: Global. Time: period Recent. Major taxa studied Trees. Methods: We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community-weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results: Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within-biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions: Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within-biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance
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