169 research outputs found
Crevettes d'eau douce en aquariophilie : exemple de maintenance de la neocaridina heteropoda pour les débutants
Ce document regroupe de nombreuses donnĂ©es sur les crevettes dâeau douce. AprĂšs avoir abordĂ© la question de la phylogĂ©nie afin de mieux apprĂ©hender la place des crustacĂ©s au sein du rĂšgne animal, lâauteur aborde leur anatomie et leur physiologie. Ainsi, le lecteur trouvera les informations nĂ©cessaires Ă la comprĂ©hension du fonctionnement des organes de la vie de relation, de nutrition ou de la reproduction des crevettes. Lâauteur explique Ă©galement comment mettre en place et entretenir un aquarium de crevettes tant au niveau des paramĂštres techniques importants Ă maĂźtriser que concernant le choix et lâaccueil des nouveaux arrivants. Une place importante sera consacrĂ©e aux pathologies rencontrĂ©es chez les espĂšces maintenues en aquarium. Lâauteur traite enfin de la maintenance dâune espĂšce robuste de crevette quâest la Neocaridina heteropoda : approche de ses origines, des dĂ©tails microscopiques de reconnaissance, des caractĂ©ristiques physiologiques et de sa place actuelle au sein de lâaquariophilie. Ce document sera Ă la fois une prĂ©sentation utile pour lâaquariophile dĂ©butant ainsi quâun outil prĂ©cieux pour lâamateur aguerri souhaitant parfaire ses connaissances
Ultrathin, flexible and MRI-compatible microelectrode array for chronic single units recording within subcortical layers
Current techniques of neuroimaging, including electrical devices, are either
of low spatiotemporal resolution or invasive, impeding multiscale monitoring of
brain activity at both single cell and network levels. Overcoming this issue is
of great importance to assess brain's computational ability and for
neurorehabilitation projects that require real-time monitoring of neurons and
concomitant networks activities. Currently, that information could be extracted
from functional MRI when combined with mathematical models. Novel methods
enabling quantitative and long-lasting recording at both single cell and
network levels will allow to correlate the MRI data with intracortical activity
at single cell level, and to refine those models. Here, we report the
fabrication and validation of ultra-thin, optically transparent and flexible
intracortical microelectrode arrays for combining extracellular multi-unit and
fMRI recordings. The sensing devices are compatible with large-scale
manufacturing, and demonstrate both fMRI transparency at 4.7 T, and high
electrical performance, and thus appears as a promising candidate for
simultaneous multiscale neurodynamic measurements
Comparative overwiew of brain perfusion imaging techniques
Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks.
Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques.
Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting
Methicillin-Resistant Coagulase-Negative Staphylococci in the Community: High Homology of SCCmec IVa between Staphylococcus epidermidis and Major Clones of Methicillin-Resistant Staphylococcus aureus
Background. Data on community spread of methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are scarce. We assessed their potential role as a reservoir of staphylococcal cassette chromosome mec (SCCmec) IVa, the leading SCCmec subtype in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). Methods. Nasal carriage of MR-CoNS was prospectively investigated in 291 adults at hospital admission. MR-CoNS were characterized by SCCmec typing, long-range polymerase chain reaction (PCR) for SCCmec IV, and multiple-locus variable-number tandem repeat analysis (MLVA) for Staphylococcus epidermidis (MRSE) strains. Three SCCmec IVa elements were fully sequenced. Results. The carriage rate of MR-CoNS was 19.2% (25.9% and 16.5% in patients with and patients without previous exposure to the health care system, respectively; P = .09). MR-CoNS strains (n=83, including 58 MRSE strains with highly heterogeneous MLVA patterns) carried SCCmec type IVa (n=9, all MRSE), other SCCmec IV subtypes (n=9, including 7 MRSE), other SCCmec types (n=15), and nontypeable SCCmec (n=50). Long-range PCR indicated structural homology between SCCmec IV in MRSE and that in MRSA. Complete sequences of SCCmec IVa from 3 MRSE strains were highly homologous to those available for CA-MRSA, including major clones USA300 and USA400. Conclusions. MR-CoNS are probably disseminated in the community, notably in subjects without previous exposure to the health care system. MRSE, the most prevalent species, may act as a reservoir of SCCmec IVa for CA-MRS
Comparative overview of brain perfusion imaging techniques Epub
Background and Purpose - Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks.
Summary of Review - This article addresses the main imaging techniques dedicated to brain hemodynamics. It represents a comparative overview established by consensus among specialists of the various techniques.
Conclusions - For clinicians, this article should offer a clearer picture of the pros and cons of currently available brain perfusion imaging techniques and assist them in choosing the proper method for every specific clinical setting
Long-term neurological outcome of a cohort of 80 patients with classical organic acidurias.
International audienceBACKGROUND: Classical organic acidurias including methylmalonic aciduria (MMA), propionic aciduria (PA) and isovaleric aciduria (IVA) are severe inborn errors of the catabolism of branched-chain amino acids and odd-numbered chain fatty acids, presenting with severe complications. METHODS: This study investigated the long-term outcome of 80 patients with classical organic aciduria (38 with MMA, 24 with PA and 18 with IVA) by integrating clinical, radiological, biochemical and genetic data. RESULTS: Patients were followed-up for a mean of 14 years [age 3.3-46.3 years]. PA included a greater number of patients with abnormal neurological examination (37% in PA, 24% in MMA and 0% in IVA), lower psychometric scores (abnormal evaluation at age 3 years in 61% of patients with PA versus 26% in MMA and 18% in IVA) and more frequent basal ganglia lesions (56% of patients versus 36% in MMA and 17% in IVA). All patients with IVA presented a normal neurological examination and only 1/3 presented cognitive troubles. Prognosis for MMA was intermediate. Biochemical metabolite analysis excluding acute decompensations revealed significant progressive increases of glycine, alanine and glutamine particularly in PA and possibly in MMA but no correlation with neurological outcome. A significant increase of plasma methylmalonic acid was found in MMA patients with intellectual deficiency (mean level of 199 mumol/L versus 70 mumol/L, p < 0.05), with an estimated significant probability of severe outcome for average levels between birth and age 6 years above 167 mumol/L. Urinary 3-hydroxypropionate (3-HP) levels were significantly higher in PA patients with intellectual deficiency (mean level of 68.9 mumol/mmol of creatinine versus 34.6 mumol/mmol of creatinine, p < 0.01), with an estimated significant probability of severe outcome for average levels between birth and age 6 years above 55 mumol/mmol. As for molecular analysis, prognosis of MMA patients with mutations involving the MMAA gene was better compared to patients with mutations involving the MUT gene. CONCLUSION: Propionic aciduria had the most severe neurological prognosis. Our radiological and biochemical data are consistent with a mitochondrial toxicity mechanism. Follow-up plasma MMA and urinary 3-HP levels may have prognostic significance calling for greater efforts to optimize long-term management in these patients
Pantropical variability in tree crown allometry
Aim
Tree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling and for the calibration of remote sensing products. Nevertheless, we know little about largeâscale variation and determinants in tropical tree crown allometry. In this study, we explored the continental variation in scaling exponents of siteâspecific crown allometry and assessed their relationships with environmental and standâlevel variables in the tropics.
Location
Global tropics.
Time period
Early 21st century.
Major taxa studied
Woody plants.
Methods
Using a dataset of 87,737 trees distributed among 245 forest and savanna sites across the tropics, we fitted siteâspecific allometric relationships between crown dimensions (crown depth, diameter and volume) and stem diameter using powerâlaw models. Standâlevel and environmental drivers of crown allometric relationships were assessed at pantropical and continental scales.
Results
The scaling exponents of allometric relationships between stem diameter and crown dimensions were higher in savannas than in forests. We identified that continental crown models were better than pantropical crown models and that continental differences in crown allometric relationships were driven by both standâlevel (wood density) and environmental (precipitation, cation exchange capacity and soil texture) variables for both tropical biomes. For a given diameter, forest trees from Asia and savanna trees from Australia had smaller crown dimensions than trees in Africa and America, with crown volumes for some Asian forest trees being smaller than those of trees in African forests.
Main conclusions
Our results provide new insight into geographical variability, with large continental differences in tropical tree crown allometry that were driven by standâlevel and environmental variables. They have implications for the assessment of ecosystem function and for the monitoring of woody biomass by remote sensing techniques in the global tropics
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
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