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51.
Dellagi K Rollot O Temmam S Salez N Guernier V Pascalis H Gérardin P Fianu A Lapidus N Naty N Tortosa P Boussaïd K Jaffar-Banjee MC Filleul L Flahault A Carrat F Favier F de Lamballerie X 《PloS one》2011,6(9):e25738
Background
To date, there is little information that reflects the true extent of spread of the pH1N1/2009v influenza pandemic at the community level as infection often results in mild or no clinical symptoms. This study aimed at assessing through a prospective study, the attack rate of pH1N1/2009 virus in Reunion Island and risk factors of infection, during the 2009 season.Methodology/Principal Findings
A serosurvey was conducted during the 2009 austral winter, in the frame of a prospective population study. Pairs of sera were collected from 1687 individuals belonging to 772 households, during and after passage of the pandemic wave. Antibodies to pH1N1/2009v were titered using the hemagglutination inhibition assay (HIA) with titers ≥1/40 being considered positive. Seroprevalence during the first two weeks of detection of pH1N1/2009v in Reunion Island was 29.8% in people under 20 years of age, 35.6% in adults (20–59 years) and 73.3% in the elderly (≥60 years) (P<0.0001). Baseline corrected cumulative incidence rates, were 42.9%, 13.9% and 0% in these age groups respectively (P<0.0001). A significant decline in antibody titers occurred soon after the passage of the epidemic wave. Seroconversion rates to pH1N1/2009 correlated negatively with age: 63.2%, 39.4% and 16.7%, in each age group respectively (P<0.0001). Seroconversion occurred in 65.2% of individuals who were seronegative at inclusion compared to 6.8% in those who were initially seropositive.Conclusions
Seroincidence of pH1N1/2009v infection was three times that estimated from clinical surveillance, indicating that almost two thirds of infections occurring at the community level have escaped medical detection. People under 20 years of age were the most affected group. Pre-epidemic titers ≥1/40 prevented seroconversion and are likely protective against infection. A concern was raised about the long term stability of the antibody responses. 相似文献52.
53.
Nino Künzli Michael Jerrett Raquel Garcia-Esteban Xavier Basaga?a Bernardo Beckermann Frank Gilliland Merce Medina John Peters Howard N. Hodis Wendy J. Mack 《PloS one》2010,5(2)
Background
Cross-sectional studies suggest an association between exposure to ambient air pollution and atherosclerosis. We investigated the association between outdoor air quality and progression of subclinical atherosclerosis (common carotid artery intima-media thickness, CIMT).Methodology/Principal Findings
We examined data from five double-blind randomized trials that assessed effects of various treatments on the change in CIMT. The trials were conducted in the Los Angeles area. Spatial models and land-use data were used to estimate the home outdoor mean concentration of particulate matter up to 2.5 micrometer in diameter (PM2.5), and to classify residence by proximity to traffic-related pollution (within 100 m of highways). PM2.5 and traffic proximity were positively associated with CIMT progression. Adjusted coefficients were larger than crude associations, not sensitive to modelling specifications, and statistically significant for highway proximity while of borderline significance for PM2.5 (P = 0.08). Annual CIMT progression among those living within 100 m of a highway was accelerated (5.5 micrometers/yr [95%CI: 0.13–10.79; p = 0.04]) or more than twice the population mean progression. For PM2.5, coefficients were positive as well, reaching statistical significance in the socially disadvantaged; in subjects reporting lipid lowering treatment at baseline; among participants receiving on-trial treatments; and among the pool of four out of the five trials.Conclusion
Consistent with cross-sectional findings and animal studies, this is the first study to report an association between exposure to air pollution and the progression of atherosclerosis – indicated with CIMT change – in humans. Ostensibly, our results suggest that air pollution may contribute to the acceleration of cardiovascular disease development – the main causes of morbidity and mortality in many countries. However, the heterogeneity of the volunteering populations across the five trials, the limited sample size within trials and other relevant subgroups, and the fact that some key findings reached statistical significance in subgroups rather than the sample precludes generalizations to the general population. 相似文献54.
Madsen PP Kibaek M Roca X Sachidanandam R Krainer AR Christensen E Steiner RD Gibson KM Corydon TJ Knudsen I Wanders RJ Ruiter JP Gregersen N Andresen BS 《Human genetics》2006,118(6):680-690
Short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD) is an autosomal recessive disorder of l-isoleucine catabolism. Little is known about the clinical presentation associated with this enzyme defect, as it has been
reported in only a limited number of patients. Because the presence of C5-carnitine in blood may indicate SBCADD, the disorder
may be detected by MS/MS-based routine newborn screening. It is, therefore, important to gain more knowledge about the clinical
presentation and the mutational spectrum of SBCADD. In the present study, we have studied two unrelated families with SBCADD,
both with seizures and psychomotor delay as the main clinical features. One family illustrates the fact that affected individuals
may also remain asymptomatic. In addition, the normal level of newborn blood spot C5-acylcarnitine in one patient underscores
the fact that newborn screening by MS/MS currently lacks sensitivity in detecting SBCADD. Until now, seven mutations in the SBCAD gene have been reported, but only three have been tested experimentally. Here, we identify and characterize an IVS3+3A>G
mutation (c.303+3A>G) in the SBCAD gene, and provide evidence that this mutation is disease-causing in both families. Using a minigene approach, we show that
the IVS3+3A>G mutation causes exon 3 skipping, despite the fact that it does not appear to disrupt the consensus sequence
of the 5′ splice site. Based on these results and numerous literature examples, we suggest that this type of mutation (IVS+3A>G)
induces missplicing only when in the context of non-consensus (weak) 5′ splice sites. Statistical analysis of the sequences
shows that the wild-type versions of 5′ splice sites in which +3A>G mutations cause exon skipping and disease are weaker on
average than a random set of 5′ splice sites. This finding is relevant to the interpretation of the functional consequences
of this type of mutation in other disease genes. 相似文献
55.
Donato Santovito Virginia Egea Kiril Bidzhekov Lucia Natarelli Andr Mouro Xavier Blanchet Kanin Wichapong Maria Aslani Coy Brunßen Michael Horckmans Michael Hristov Arie Geerlof Esther Lutgens Mat J. A. P. Daemen Tilman Hackeng Christian Ries Triantafyllos Chavakis Henning Morawietz Ronald Naumann Philipp Von Hundelshausen Sabine Steffens Johan Duchêne Remco T. A. Megens Michael Sattler Christian Weber 《Autophagy》2020,16(12):2294
56.
57.
Xavier López‐Medellín Exequiel Ezcurra Charlotte González‐Abraham Jon Hak Louis S. Santiago James O. Sickman 《植被学杂志》2011,22(1):143-151
Question: Although mangrove forests are generally regarded as highly threatened, some studies have shown that mangrove canopies in the Pacific coast of Mexico have been increasing in recent decades. We investigated the possible causes driving this reported mangrove expansion. Location: The mangrove lagoons of Magdalena Bay in Baja California, Mexico. Methods: We used 50‐year‐old aerial photographs and 24‐year‐old satellite images to compare long‐term vegetation change, surveyed a coastal vegetation transect to analyse flooding levels, compiled six decades of tidal and oceanographic information, as well as hurricane data to analyse changes in storm frequency or sea‐level conditions, and used isotopic analysis to date the age of trees along the gradient. Results: A significant increase in mangrove cover has occurred in backwaters of the lagoons during the last 40 years, and especially during the El Niño anomalies of the 1980s and 1990s, while at the same time the mangrove fringe has been receding. Conclusions: The observed change can be attributed to the combined action of the warm surface waters of El Niño events and sea‐level rise. Jointly, these two effects are sufficient to flood large areas of previously non‐flooded salt flats, dispersing mangrove seedlings inland. The inland expansion of mangroves, however, does not ease conservation concerns, as it is the seaward fringes, and not the inland margins, that provide the most valuable environmental services for fisheries and coastal protection. 相似文献
58.
Belinda Gallardo Stéphanie Gascón Xavier Quintana Franciso A. Comín 《Ecological Indicators》2011,11(5):1177-1184
A range of biodiversity metrics are available to assess the ecological integrity of aquatic ecosystems. However, performance varies considerably among different types of metrics and provides different information regarding ecosystem conditions, thus making difficult the selection of appropriate metrics for biomonitoring. The present study evaluated the robustness of six biodiversity metrics to assess environmental change and determine their utility as relevant indicators of ecosystem biodiversity and functionality. Traditional metrics such as species richness and Shannon diversity were considered along with alternative metrics such as functional diversity, size diversity and taxonomic distinctness. To that end, invertebrate assemblages in a river floodplain were used as a case study to evaluate the performance of metrics using Generalized Additive Models (GAM). GAM explained between eight and 49% of the variability in biodiversity. The regression models exhibited differences in the response of biodiversity indicators to environmental factors, suggesting that intermediate levels of turbidity and low salinity are conditions favouring increased biodiversity in the study area. Based on correlations among metrics and responses to primary environmental factors, it is concluded that Shannon and functional diversity, and rarefied species richness generated similar information regarding ecosystem conditions (i.e., the metrics were redundant); while size diversity and distinctness provided useful additional data characterizing ecosystem quality (i.e., the metrics were complementary). Functional diversity indicated not only number and dominance of species, but also each species functional role in the community, and was therefore the most informative biodiversity metric. Nevertheless, the use of a combination of metrics, for example functional and size diversity, and variation in taxonomic distinctness, provides complementary data that will serve to achieve a more thorough understanding of ecosystem structure and function, and response to primary environmental influences. 相似文献
59.
Characterization of a two-component high-affinity nitrate uptake system in Arabidopsis. Physiology and protein-protein interaction 下载免费PDF全文
Orsel M Chopin F Leleu O Smith SJ Krapp A Daniel-Vedele F Miller AJ 《Plant physiology》2006,142(3):1304-1317
The identification of a family of NAR2-type genes in higher plants showed that there was a homolog in Arabidopsis (Arabidopsis thaliana), AtNAR2.1. These genes encode part of a two-component nitrate high-affinity transport system (HATS). As the Arabidopsis NRT2 gene family of nitrate transporters has been characterized, we tested the idea that AtNAR2.1 and AtNRT2.1 are partners in a two-component HATS. Results using the yeast split-ubiquitin system and Xenopus oocyte expression showed that the two proteins interacted to give a functional HATS. The growth and nitrogen (N) physiology of two Arabidopsis gene knockout mutants, atnrt2.1-1 and atnar2.1-1, one for each partner protein, were compared. Both types of plants had lost HATS activity at 0.2 mm nitrate, but the effect was more severe in atnar2.1-1 plants. The relationship between plant N status and nitrate transporter expression revealed a pattern that was characteristic of N deficiency that was again stronger in atnar2.1-1. Plants resulting from a cross between both mutants (atnrt2.1-1 x atnar2.1-1) showed a phenotype like that of the atnar2.1-1 mutant when grown in 0.5 mm nitrate. Lateral root assays also revealed growth differences between the two mutants, confirming that atnar2.1-1 had a stronger phenotype. To show that the impaired HATS did not result from the decreased expression of AtNRT2.1, we tested if constitutive root expression of a tobacco (Nicotiana plumbaginifolia) gene, NpNRT2.1, previously been shown to complement atnrt2.1-1, can restore HATS to the atnar2.1-1 mutant. These plants did not recover wild-type nitrate HATS. Taken together, these results show that AtNAR2.1 is essential for HATS of nitrate in Arabidopsis. 相似文献
60.
Marta Marcos-García Esther Menéndez Xavier Cruz-González Encarna Velázquez Pedro F. Mateos Raúl Rivas 《Symbiosis (Philadelphia, Pa.)》2015,67(1-3):11-20
The diversity of rhizobia that establish symbiosis with Lotus corniculatus has scarcely been studied. Several species of Mesorhizobium are endosymbionts of this legume, including Mesorhizobium loti, the type species of this genus. We analysed the genetic diversity of strains nodulating Lotus corniculatus in Northwest Spain and ten different RAPD patterns were identified among 22 isolates. The phylogenetic analysis of the 16S rRNA gene showed that the isolated strains belong to four divergent phylogenetic groups within the genus Mesorhizobium. These phylogenetic groups are widely distributed worldwide and the strains nodulate L. corniculatus in several countries of Europe, America and Asia. Three of the groups include the currently described Mesorhizobium species M. loti, M. erdmanii and M. jarvisii which are L. corniculatus endosymbionts. An analysis of the recA and atpD genes showed that our strains belong to several clusters, one of them very closely related to M. jarvisii and the remanining ones phylogenetically divergent from all currently described Mesorhizobium species. Some of these clusters include L. corniculatus nodulating strains isolated in Europe, America and Asia, although the recA and atpD genes have been sequenced in only a few L. corniculatus endosymbionts. The results of this study revealed great phylogenetic diversity of strains nodulating L. corniculatus, allowing us to predict that even more diversity will be discovered as further ecosystems are investigated. 相似文献