37 research outputs found
Rapid Etiological Classification of Meningitis by NMR Spectroscopy Based on Metabolite Profiles and Host Response
Bacterial meningitis is an acute disease with high mortality that is reduced by early treatment. Identification of the causative microorganism by culture is sensitive but slow. Large volumes of cerebrospinal fluid (CSF) are required to maximise sensitivity and establish a provisional diagnosis. We have utilised nuclear magnetic resonance (NMR) spectroscopy to rapidly characterise the biochemical profile of CSF from normal rats and animals with pneumococcal or cryptococcal meningitis. Use of a miniaturised capillary NMR system overcame limitations caused by small CSF volumes and low metabolite concentrations. The analysis of the complex NMR spectroscopic data by a supervised statistical classification strategy included major, minor and unidentified metabolites. Reproducible spectral profiles were generated within less than three minutes, and revealed differences in the relative amounts of glucose, lactate, citrate, amino acid residues, acetate and polyols in the three groups. Contributions from microbial metabolism and inflammatory cells were evident. The computerised statistical classification strategy is based on both major metabolites and minor, partially unidentified metabolites. This data analysis proved highly specific for diagnosis (100% specificity in the final validation set), provided those with visible blood contamination were excluded from analysis; 6-8% of samples were classified as indeterminate. This proof of principle study suggests that a rapid etiologic diagnosis of meningitis is possible without prior culture. The method can be fully automated and avoids delays due to processing and selective identification of specific pathogens that are inherent in DNA-based techniques
Fingerprinting microbiomes towards screening for microbial antibiotic resistance
There is an increasing need to investigate microbiomes in their entirety in a variety of contexts ranging from environmental to human health scenarios. This requirement is becoming increasingly important with emergence of antibiotic resistance. In general, more conventional approaches are too expensive and/or time-consuming and often predicated on prior knowledge of the microorganisms one wishes to study. Herein, we propose the use of biospectroscopy tools as relatively high-throughput, non-destructive approaches to profile microbiomes under study. Fourier-transform infrared (FTIR) or Raman spectroscopy both generate fingerprint spectra of biological material and such spectra can readily be subsequently classed according to biochemical changes in the microbiota, such as emergence of antibiotic resistance. FTIR spectroscopy techniques generally can only be applied to desiccated material whereas Raman approaches can be applied to more hydrated samples. The ability to readily fingerprint microbiomes could lend itself to new approaches in determining microbial behaviours and emergence of antibiotic resistance
A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS measured from stellar occultations
This work aims at constraining the size, shape, and geometric albedo of the
dwarf planet candidate 2002 MS4 through the analysis of nine stellar
occultation events. Using multichord detection, we also studied the object's
topography by analyzing the obtained limb and the residuals between observed
chords and the best-fitted ellipse. We predicted and organized the
observational campaigns of nine stellar occultations by 2002 MS4 between 2019
and 2022, resulting in two single-chord events, four double-chord detections,
and three events with three to up to sixty-one positive chords. Using 13
selected chords from the 8 August 2020 event, we determined the global
elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the
object's rotational information from the literature, constrains the object's
size, shape, and albedo. Additionally, we developed a new method to
characterize topography features on the object's limb. The global limb has a
semi-major axis of 412 10 km, a semi-minor axis of 385 17 km, and
the position angle of the minor axis is 121 16. From
this instantaneous limb, we obtained 2002 MS4's geometric albedo and the
projected area-equivalent diameter. Significant deviations from the fitted
ellipse in the northernmost limb are detected from multiple sites highlighting
three distinct topographic features: one 11 km depth depression followed by a
25 km height elevation next to a crater-like depression with an
extension of 322 39 km and 45.1 1.5 km deep. Our results present an
object that is 138 km smaller in diameter than derived from thermal
data, possibly indicating the presence of a so-far unknown satellite. However,
within the error bars, the geometric albedo in the V-band agrees with the
results published in the literature, even with the radiometric-derived albedo
Caractérisation de la flore sulfato / thiosulfato réductrice par spectroscopie infrarouge à transformée de fourier (IRTF)
La présence de certaines bactéries au sein d'un
biofilm peut soit accélérer un processus de corrosion déjà établi, soit créer des conditions favorables à son élaboration. Les souches
principalement décrites comme étant les plus agressives vis-à -vis des matériaux métalliques sont les Bactéries Sulfato/Thiosulfato Réductrices (BSR et BTR). Il paraßt donc important de les détecter rapidement lorsqu'elles colonisent un milieu afin de pouvoir diagnostiquer les problÚmes et déployer les moyens de lutte appropriés. Malheureusement les
techniques actuelles d'identification sont coûteuses et/ou peu rapides. Nous avons donc tenté de caractériser plusieurs souches de BSR/BTR provenant de la collection DSMZ par spectroscopie infrarouge à transformée de Fourier.
Les résultats de la classification hiérarchique des spectres
infrarouge sur les fenĂȘtres spectrales 3100-2800 cm-1 et 1500-700 cm-1 ont permis de sĂ©parer en deux groupes bien distincts les BSR et la BTR Ă©tudiĂ©es, mais aussi de diffĂ©rencier les BSR au niveau
espÚce. L'introduction de spectres de bactéries de contamination fécale dans l'analyse scinde le dendrogramme, les BSR/BTR restant groupées entre elles.
La spectroscopie IRTF différencie avec succÚs les BSR et la BTR
étudiées et devrait permettre, aprÚs enrichissement de la bibliothÚque en spectres de nouvelles espÚces, une caractérisation des souches sulfurogÚnes à partir d'échantillons prélevés en eau de mer
Nature, structure and strength of the acidic sites of amorphous silica alumina: An IR and NMR study
International audienc
Conversion paralysis after cervical spine arthroplasty: A case report and literature review
AbstractWe report a case of conversion paralysis after cervical spine arthroplasty performed in a 45-year-old woman to treat cervico-brachial neuralgia due to a left-sided C6âC7 disc herniation. Upon awakening from the anaesthesia, she had left hemiplegia sparing the face, with normal sensory function. Magnetic resonance imaging (MRI) of the brain ruled out a stroke. MRI of the spinal cord showed artefacts from the cobalt-chrome prosthesis that precluded confident elimination of mechanical spinal cord compression. Surgery performed on the same day to substitute a cage for the prosthesis ruled out spinal cord compression, while eliminating the source of MRI artefacts. Findings were normal from follow-up MRI scans 1 and 15days later, as well as from neurophysiological testing (electromyogram and motor evoked potentials). The deficit resolved fully within the next 4days. A psychological assessment revealed emotional distress related to an ongoing divorce. The most likely diagnosis was conversion paralysis. Surgeons should be aware that conversion disorder might develop after a procedure on the spine, although the risk of litigation requires re-operation. Familiarity with specific MRI sequences that minimise artefacts can be valuable. A preoperative psychological assessment might improve the detection of patients at high risk for conversion disorder
Hydrodeoxygenation of Phenolic Compounds by Sulfided (Co)Mo/Al2O3 Catalysts, a Combined Experimental and Theoretical Study
International audienceThe hydrodeoxygenation of model phenol compounds (phenol and 2-ethylphenol) was carried over unpromoted Mo/Al2O3 and promoted CoMo/Al2O3 catalysts. Hydrodeoxygenation proceeds by two pathways:â hydrogenation of the aromatic ring followed by Csp3-O bond cleavage (HYD pathway, (hydrogenation of the aromatic ring followed by Csp3-O bond cleavage));â direct cleavage of the Csp2-O bond (DDO Pathway).Both routes were favored by the presence of Co on the catalyst, while the presence of the alkyl substituent on the phenolic ring favors the DDO route but inhibits the HYD pathway. IR (InfraRed) spectroscopy shows that while phenol mostly dissociates on these catalysts, a significant fraction of 2-ethylphenol remains non dissociated. The adsorption energies of both reactants and possible reaction intermediates on promoted and non-promoted sulfide phases as computed by DFT (Density-Functional Theory) confirm these findings and allow rationalizing the catalytic activity trends observed experimentally