Preferred metabolic pathway of bovine muscle fibre revealed by synchrotron–deep ultraviolet fluorescence imaging

International audienceThe different bovine muscle fibre types I, IIA and IIX are characterised by their preferred metabolic pathway, either oxidative (I, IIA) or glycolytic (IIX), and their contraction speed, either slow-twitch (I) or fast-twitch (IIA, IIX). These physiological specificities are associated with variations in intracellular composition and their fluorescence spectra signatures. We hypothesised that these slight differences in autofluorescence responses could be used to discriminate the muscle fibre types by fluorescence imaging. Serial histological cross-sections of beef longissimus dorsi were performed: the start set was used to identify the metabolic and contractile type of muscle fibres by both immunohistoenzymology and immunohistofluorescence, and the following set was used to acquire synchrotron–deep ultraviolet (UV) autofluorescence images after excitation in the UV range (275 nm and 315 nm). This strategy made it possible to explore the label-free autofluorescence of muscle cells previously subtyped by histochemistry. Glycolytic cells (IIX) showed more intense fluorescence than oxidative cells (I and IIA) with near-90 % accuracy. This discrimination is more specifically assigned to the fluorescence of nicotinamide adenine dinucleotide. UV autofluorescence was unable to discriminate contractile type

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Imagerie plasmonique multimodale en vue d'applications biomédicales

Surface plasmons are collective oscillation modes of the conductive electrons at the interface between a metal and a dielectric. Plasmonic is a field of optics based on the properties of containment and exaltation of the electromagnetic field given by this mode. Plasmonics is particulary used in biosensors to quantify and to follow interaction dynamic between biomolecules. The specificity of these sensors named Surface Plasmon Resonance (SPR) is their unstrained characteristic. SPR sensitivity relies on the strong dependence of the resonance conditions to the refractive index of the studied dielectric. In particular, the refractive index depends on the biomolecules concentration at the sensor surface. Here, we suggest to use an original device in transmission (tSPR) preserving the strong sensitivity characteristic of standard SPR. We show that this configuration allows a high parallelization density of measurement. Multiplexing given by tSPR is around one order of magnitude more than the one of classical SPR. Propagative surface plasmon (PSP) is associated with an evanescent field. The high intensity of the field and its strong axial confinement have been recently been used in Surface Plasmon mediated Fluorescence (SPF) imaging. Moreover, the presence of a metallic interface in the vicinity of a fluorescent dye induces new relaxation processes, especially via the surface Plasmon, producing a sharp decrease of the fluorescence lifetime. Lifetime information can be extract with a fluorescence lifetime imaging microscope (FLIM). We show that FLIM imaging coupled with surface Plasmon provides nanometric accuracy of the dye-metal distance. We show that such a device is adapted to plasmic membrane tomography with an axial resolution about 15 nm.Les plasmons de surface sont des modes d'oscillation collectifs des électrons de conduction à l'interface entre métal et diélectrique. La plasmonique est un domaine de l'optique basé sur les propriétés de confinement et d'exaltation du champ électromagnétique offertes par ces modes. La plasmonique est en particulier utilisée dans les biocapteurs en permettant de quantifier et de suivre la dynamique d'interaction de biomolécules. La spécificité de ces capteurs dits à résonance de plasmon de surface, connus sous l'acronyme anglais SPR, est qu'ils ne nécessitent aucun marquage. La sensibilité de la SPR repose sur la forte dépendance des conditions de résonance à l'indice de réfraction local du diélectrique étudié. En particulier, l'indice de réfraction varie en fonction de la concentration en biomolécules à la surface du capteur. Nous proposons ici un dispositif original en transmission (tSPR) préservant la forte sensibilité caractéristique de la SPR standard. Nous montrons que cette configuration permet une haute densité de parallélisation des mesures. Le multiplexage offert par la tSPR est supérieur d'environ un ordre de gràndeur à celle de la SPR classique. Le plasmon de surface propagatif (PSP) est associé à un champ évanescent.L'intensité élevée du champ et son fort confinement axial ont été récemment mis à profit dans des expériences d'imagerie de fluorescence médiée par les plasmons de surface (SPF). De plus, la présence d'une interfade métallique au voisinage d'un fluorophore induit de nouveaux mécanismes de relaxation, notamment via le plasmon de surface, provoquant une chute abrupte de la durée de vie de fluorescence. L'information de durée de vie peut être extraite à l'aide d'un microscope d'imagerie de temps de vie de fluorescence (FLIM). Nous montrons que l'imagerie FLIM couplée avec des plasmons de surface permet obtenir une mesure nanométrique de la distance métal-fluorphore. Nous montrons qu'un tel dispositif est adapté à la tomographique de membrane plasmique sur des cellules avec une résolution axiale de l'ordre de 15 nm.PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Pepsin localization in digested meat by ToF-SIMS analysis

Meat, is a highly structured product consisting of muscle fibres, lipids and connective tissue sheaths. These differents compounds are suspected of modulating the diffusion of digestive enzymes in meat during its gastric digestion. To follow the pepsin diffusion in digested meat and better understand the role of meat structure organization we investigated the use of high resolution time of flight secondary-ion mass spectrometry (Tof-SIMS) imaging to detect pepsin in food. Two beef muscle samples (1.5 X 1.5 X 2.5 cm) were incubated in a pepsin solution at pH 2. After 2 hours incubation at 37°C under agitation, the samples were cryofixed, histological sections were collected on glass slides and used for chemical imaging. The entire surface area of the sections (1.5 X 1.5 cm) was mapped by ToF-SIMS imaging (ToF-SIMS V; ION-TOF GmbH, Münster,Germany). Mass spectra of commercial pepsin powder and aqueous solution were acquired using the same tool.Pepsin powder analyzes revealed signals of nitrogen species that seems to be characteristic of pepsin.Lipids and connective tissue were revealed by the map which also exhibit large amounts of chlorine on the periphery of the section associated with a depletion of phosphorus species. This result reflects the penetration of the digestion solution which is rich in HCl, and that probably extract the soluble endogenous phosphorus compounds.Finally, an enrichment in nitrogen species CxHyN, assigned to pepsin, was observed in the penetration zone of the digestive solution, but also along the connective tissue layers.The use of ToF SIMS allowed the visualization of pepsin in a food. This result opens great perspectives to understanding the mechanisms of digestion of solid foods

Characteristics of femtosecond laser-induced shockwaves in air

International audienceDynamic characteristics of femtosecond laser-generated shockwaves are investigated in ambient air. The experiments are performed using a 360-fs pulsed laser at a wavelength of 1.03 µm, with laser intensities up to 5 × 10 14 W/cm 2 (corresponding to about five times the air breakdown intensity threshold). Plasma and shockwave generation and propagation are visualized using a time-resolved transmission microscope. The maximum propagation velocity is in the order of Mach 30. By implementing a simple theoretical model, we find an initial pressure loading in the GPa range and shockwave pressure dropping down to MPa following propagation over few micrometers away from focus

Study of femtosecond laser-induced shockwaves in air

International audienc

Structural changes of local thai beef during sous-vide cooking

Structural changes of local thai beef during sous-vide cooking. 64. International Congress of Meat Science and Technolog

Characterization of smoked salmon by infrared spectroscopy

Smoked salmon results from the salting of the fillets, followed by smoking. Salting and smoking methods may vary depending on different recipes specific to each manufacturer and can cause variability in the composition of the end product.The aim of this work was to try to classify a posteriori two processes of production of smoked salmon by simple analyzes of near and medium infrared spectroscopy.The experiment was carried out on 6 salmons. For each salmon, 1 filet was salted and smoked according to the process A, the other filet was salted and smoked according to process B. Processes from industrial production are confidential.Samples were taken and analyzed both in near infrared spectroscopy (Foss NIRSystems model 6500) and in medium infrared microspctroscopy (IN10 Mx Thermo Scientific). The spectra were pre-processed and the multivariate analyzes implemented using the software "The Unscrambler".Principal component analyzes (PCAs) reveal spectral signatures (NIRS and MIR) which are characteristic of each process and therefore allow to discriminate at posteriori the samples from each process (A and B).This experiment demonstrates the power of infrared spectroscopy methods to characterize smoked salmon fillets and identified their technological itinerary