45 research outputs found
Understanding multivalent effects in glycosidase inhibition using C-glycoside click clusters as molecular probes
The synthesis of the first examples of multivalent C-glycosides based on C60-fullerene or ÎČ-cyclodextrin cores by way of Cu(I)-catalyzed azideâalkyne cycloadditions is reported. These compounds were designed as molecular probes to understand the mechanisms underlying the outstanding multivalent effects observed in glycosidase inhibition. The inhibition results obtained support a multivalent-binding model based on two scenarios both involving nonspecific interactions and varying by the presence or the absence of active site specific interactions. The magnitude of the multivalent effect obtained depends on the identity of the glycosidase involved and more specifically on the accessibility of its catalytic active site. Large inhibitory multivalent effects can be obtained when both glycosidase active sites and non-catalytic sites at the protein surface are involved in binding events. On the other hand, nonspecific interactions alone are not sufficient to achieve relative affinity enhancements exceeding a simple statistical effect (i.e., a relative inhibition potency not better than one on a valence-corrected basis).Ministerio de EconomĂa y Competitividad de España (MINECO) y Fondos Europeos de Desarrollo Regional (FEDER y FSE). SAF2013-44021-
Thermo-compositional diabatic convection in the atmospheres of brown dwarfs and in Earth's atmosphere and oceans
This is the author accepted manuscript. The final version is available from the American Astronomical Society / IOP Publishing via the DOI in this record.The simulation outputs are available at http://opendata.erc-atmo.euBy generalizing the theory of convection to any type of thermal and compositional source terms (diabatic processes), we show that thermohaline convection in Earth oceans, fingering convection in stellar atmospheres, and moist convection in Earth atmosphere are deriving from the same general diabatic convective instability. We show also that "radiative convection" triggered by CO/CH4 transition with radiative transfer in the atmospheres of brown dwarfs is analog to moist and thermohaline convection. We derive a generalization of the mixing length theory to include the effect of source terms in 1D codes. We show that CO/CH4 radiative convection could significantly reduce the temperature gradient in the atmospheres of brown dwarfs similarly to moist convection in Earth atmosphere thus possibly explaining the reddening in brown-dwarf spectra. By using idealized two-dimensional hydrodynamic simulations in the Ledoux unstable regime, we show that compositional source terms can indeed provoke a reduction of the temperature gradient. The L/T transition could be explained by a bifurcation between the adiabatic and diabatic convective transports and could be seen as a giant cooling crisis: an analog of the boiling crisis in liquid/steam-water convective flows. This mechanism with other chemical transitions could be present in many giant and earth-like exoplanets. The study of the impact of different parameters (effective temperature, compositional changes) on CO/CH4 radiative convection and the analogy with Earth moist and thermohaline convection is opening the possibility to use brown dwarfs to better understand some aspects of the physics at play in the climate of our own planet.Science and Technology Facilities Council (STFC
Frequency of Chlamydia trachomatis infection in cervical intraepithelial lesions and the status of cytological p16/Ki-67 dual-staining
Background: Chlamydia trachomatis (Ct) is not a disease subject to mandatory reporting in Brazil, and the prevalence rate of this genital infection varies according to the region in which studies are conducted, as well as by the detection technique employed. Ct has been associated with persistence of Human papillomavirus (HPV) infection and the facilitation of cervical carcinoma development. We evaluated the Chlamydia trachomatis infection and its association with cytology, p16/Ki-67 dual-stained cytology and cervical intraepithelial lesions status in a screening cohort in Brazil.
Methods: This was a cross-sectional study of 1481 cervical samples from asymptomatic women aged 18 to 64. Samples were collected for liquid-based cytology and Ct detection by polymerase chain reaction. p16/Ki-67 double staining was performed on samples with abnormal cytology. Statistical analysis was by chi-square and likelihood-ratio tests. Odds ratio (OR) and 95% confidence intervals (95% CI) were determined.
Results: The frequency of Ct was 15.6% and its presence was not associated with detection of p16/Ki-67 [OR = 1. 35 (0.5-3.4)]. There was also no association between abnormal cervical cytology and Ct-positivity [OR = 1.21 (0.46-3.2)]. Associations were observed between p16/Ki-67 and high-grade lesions detected by cytology and in biopsies [OR = 3.55 (1.50-8.42) and OR = 19.00 (0.6-7.2), respectively].
Conclusions: The asymptomatic women in our study had a high frequency of Ct infection but this was not associated with p16/Ki-67 detection in samples with abnormal cytology. The expression of p16/Ki-67 was highest in women with high-grade CIN (p = 0.003).info:eu-repo/semantics/publishedVersio
Dynamics and distribution of bacterial and archaeal communities in oil-contaminated temperate coastal mudflat mesocosms
Mudflats are ecologically important habitats that are susceptible to oil pollution, but intervention is difficult in these fine-grained sediments, and so clean-up usually relies on natural attenuation. Therefore, we investigated the impact of crude oil on the bacterial, diatom and archaeal communities within the upper parts of the diatom-dominated sediment and the biofilm that detached from the surface at high tide. Biodegradation of petroleum hydrocarbons was rapid, with a 50Â % decrease in concentration in the 0â2-mm section of sediment by 3Â days, indicating the presence of a primed hydrocarbon-degrading community. The biggest oil-induced change was in the biofilm that detached from the sediment, with increased relative abundance of several types of diatom and of the obligately hydrocarbonoclastic Oleibacter sp., which constituted 5Â % of the pyrosequences in the oiled floating biofilm on day 3 compared to 0.6Â % in the non-oiled biofilm. Differences in bacterial community composition between oiled and non-oiled samples from the 0â2-mm section of sediment were only significant at days 12 to 28, and the 2â4-mm-sediment bacterial communities were not significantly affected by oil. However, specific members of the Chromatiales were detected (1Â % of sequences in the 2â4-mm section) only in the oiled sediment, supporting other work that implicates them in anaerobic hydrocarbon degradation. Unlike the Bacteria, the archaeal communities were not significantly affected by oil. In fact, changes in community composition over time, perhaps caused by decreased nutrient concentration and changes in grazing pressure, overshadowed the effect of oil for both Bacteria and Archaea. Many obligate hydrocarbonoclastic and generalist oil-degrading bacteria were isolated, and there was little correspondence between the isolates and the main taxa detected by pyrosequencing of sediment-extracted DNA, except for Alcanivorax, Thalassolituus, Cycloclasticus and Roseobacter spp., which were detected by both methods
Chlamydia trachomatis infection in young pregnant women in Southern Brazil: a cross-sectional study
Impact of oil on bacterial community structure in bioturbated sediments
Oil spills threaten coastlines where biological processes supply essential ecosystem services. Therefore, it is crucial to understand how oil influences the microbial communities in sediments that play key roles in ecosystem functioning. Ecosystems such as sediments are characterized by intensive bioturbation due to burrowing macrofauna that may modify the microbial metabolisms. It is thus essential to consider the bioturbation when determining the impact of oil on microbial communities. In this study, an experimental laboratory device maintaining pristine collected mudflat sediments in microcosms closer to true environmental conditions - with tidal cycles and natural seawater - was used to simulate an oil spill under bioturbation conditions. Different conditions were applied to the microcosms including an addition of: standardized oil (Blend Arabian Light crude oil, 25.6 mg.g21 wet sediment), the common burrowing organism Hediste (Nereis) diversicolor and both the oil and H. diversicolor. The addition of H. diversicolor and its associated bioturbation did not affect the removal of petroleum hydrocarbons. After 270 days, 60% of hydrocarbons had been removed in all microcosms irrespective of the H. diversicolor addition. However, 16S-rRNA gene and 16S-cDNA T-RFLP and RT-PCR-amplicon libraries analysis showed an effect of the condition on the bacterial community structure, composition, and dynamics, supported by PerMANOVA analysis. The 16S-cDNA libraries from microcosms where H. diversicolor was added (oiled and un-oiled) showed a marked dominance of sequences related to Gammaproteobacteria. However, in the oiled-library sequences associated to Deltaproteobacteria and Bacteroidetes were also highly represented. The 16S-cDNA libraries from oiled-microcosms (with and without H. diversicolor addition) revealed two distinct microbial communities characterized by different phylotypes associated to known hydrocarbonoclastic bacteria and dominated by Gammaproteobacteria and Deltaproteobacteria. In the oiled-microcosms, the addition of H. diversicolor reduced the phylotype-richness, sequences associated to Actinobacteria, Firmicutes and Plantomycetes were not detected. These observations highlight the influence of the bioturbation on the bacterial community structure without affecting the biodegradation capacities
A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)
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Structure of hydrocarbonoclastic nitrate-reducing bacterial communities in bioturbated coastal marine sediments
International audienceThe organisation of denitrifying microorganisms in oil-polluted bioturbated sediments was investigated in mesocosms under conditions as closer as possible to that observed in the environment. Molecular and culture-dependent approaches revealed that denitrifying Gammaproteobacteria were abundant in oil-polluted and bioturbated sediments suggesting that they may play a key role in hydrocarbon degradation in the environment. T-RFLP and gene libraries analyses targeting nirS gene showed that denitrifying microbial communities structure was slightly affected by either the addition of Hediste diversicolor or crude oil revealing the metabolic versatility of denitrifying microorganisms. From oil-polluted sediments, distinct denitrifying hydrocarbonoclastic bacterial consortia were obtained by enrichment cultures on high molecular weight polyaromatic hydrocarbons (PAHs) (dibenzothiophene, fluoranthene, pyrene and chrysene) under nitrate-reducing conditions. Interestingly, molecular characterisation of the consortia showed that the denitrifying communities obtained from oiled microcosms with addition of H. diversicolor were different to that observed without H. diversicolor addition, especially with fluoranthene and chrysene revealing the bacterial diversity involved in the degradation of these PAHs. The manuscript describes the structure of denitrifying community during oil degradation in bioturbated marine sediments, by molecular and culture-dependent approaches
Dynamic of sulphate-reducing microorganisms in petroleum-contaminated marine sediments inhabited by the polychaete Hediste diversicolor
cited By 1International audienceThe behaviour of sulphate-reducing microbial community was investigated at the oxicâanoxic interface (0â2Â cm) of marine sediments when submitted to oil and enhanced bioturbation activities by the addition of Hediste diversicolor. Although total hydrocarbon removal was not improved by the addition of H. diversicolor, terminal restriction fragment length polymorphism (T-RFLP) analyses based on dsrAB (dissimilatory sulphite reductase) genes and transcripts showed different patterns according to the presence of H. diversicolor which favoured the abundance of dsrB genes during the early stages of incubation. Complementary DNA (cDNA) dsrAB libraries revealed that in presence of H. diversicolor, most dsrAB sequences belonged to hydrocarbonoclastic Desulfobacteraceae, suggesting that sulphate-reducing microorganisms (SRMs) may play an active role in hydrocarbon biodegradation in sediments where the reworking activity is enhanced. Furthermore, the presence of dsrAB sequences related to sequences found associated to environments with high dinitrogen fixation activity suggested potential N2 fixation by SRMs in bioturbated-polluted sediments