Pulse oximetry in the oesophagus

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO(2)) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Since central blood flow may be preferentially preserved, this review explores a new alternative site, the oesophagus, for monitoring blood oxygen saturation by pulse oximetry. This review article presents the basic physics, technology and applications of pulse oximetry including photoplethysmography. The limitations of this technique are also discussed leading to the proposed development of the oesophageal pulse oximeter. In the majority, the report will be focused on the description of a new oesophageal photoplethysmographic/SpO(2) probe, which was developed to investigate the suitability of the oesophagus as an alternative monitoring site for the continuous measurement of SpO(2) in cases of poor peripheral circulation. The article concludes with a review of reported clinical investigations of the oesophageal pulse oximeter

In vivo assembly of the axon initial segment in motor neurons

International audienceThe axon initial segment (AIS) is responsible for both the modulation of action potentials and the maintenance of neuronal polarity. Yet, the molecular mechanisms controlling its assembly are incompletely understood. Our study in single electroporated motor neurons in mouse embryos revealed that AnkyrinG (AnkG), the AIS master organizer, is undetectable in bipolar migrating motor neurons, but is already expressed at the beginning of axonogenesis at E9.5 and initially distributed homogeneously along the entire growing axon. Then, from E11.5, a stage when AnkG is already apposed to the membrane, as observed by electron microscopy, the protein progressively becomes restricted to the proximal axon. Analysis on the global motor neurons population indicated that Neurofascin follows an identical spatio-temporal distribution, whereas sodium channels and beta 4-spectrin only appear along AnkG(+) segments at E11.5. Early patch-clamp recordings of individual motor neurons indicated that at E12.5 these nascent AISs are already able to generate spikes. Using knock-out mice, we demonstrated that neither beta 4-spectrin nor Neurofascin control the distal-to-proximal restriction of AnkG

B-cell receptor signal strength influences terminal differentiation

B-cell terminal differentiation into antibody secreting plasma cells (PCs) features a trans-criptional shift driven by the activation of plasma cell lineage determinants such as Blimp-1 and Xbp-1, together with the extinction of Pax5. Little is known about the signals inducing this change in transcriptional networks and the role of the B-cell receptor (BCR) in terminal differentiation remains especially controversial. Here, we show that tonic BCR signal strength influences PC commitment in vivo. Using immuno-globulin light chain transgenic mice expressing suboptimal surface BCR levels and latent membrane protein 2A knock-in animals with defined BCR-like signal strengths, we show that weak, antigen-independent constitutive BCR signaling facilitates spontaneous PC differentiation in vivo and in vitro in response to TLR agonists or CD40/IL-4. Conversely, increasing tonic signaling completely prevents this process that is rescued by lowering surface BCR expression or through the inhibition of Syk phosphorylation. These findings provide new insights into the role of basal BCR signaling in PC differentiation and point to the need to resolve a strong BCR signal in order to guarantee terminal differentiation

Recherches sur l’immunisation anticlaveleuse I. — Sur la vaccination en un seul temps contre la clavelée et la fièvre charbonneuse, avec des antigènes vivants, associés et stabilisés

Delpy Louis-Pierre, Rafyi A., Chamsy H. Mir. Recherches sur l’immunisation anticlaveleuse : I. Sur la vaccination en un seul temps contre la clavelée et la fièvre charbonneuse avec des antigènes vivants, associés et stabilisés. In: Bulletin de l'Académie Vétérinaire de France tome 104 n°1, 1951. pp. 50-55

X-ray magnetic and natural circular dichroism from first principles: Calculation of K- and L-1-edge spectra

An efficient first-principles approach to calculate x-ray magnetic circular dichroism (XMCD) and x-ray natural circular dichroism (XNCD) is developed and applied in the near-edge region at the K and L-1 edges in solids. Computation of circular dichroism requires precise calculations of x-ray absorption spectra (XAS) for circularly polarized light. For the derivation of the XAS cross section, we used a relativistic description of the photon-electron interaction that results in an additional term in the cross section that couples the electric dipole operator with an operator sigma . (is an element of x r) that we call the spin position operator. The numerical method relies on pseudopotentials, on the gauge including projected augmented-wave method, and on a collinear spin relativistic description of the electronic structure. We apply the method to calculations of K-edge XMCD spectra of ferromagnetic iron, cobalt, and nickel and of I L-1-edge XNCD spectra of alpha-LiIO3, a compound with broken inversion symmetry. For XMCD spectra we find that, even if the electric dipole term is the dominant one, the electric quadrupole term is not negligible (8% in amplitude in the case of iron). The term coupling the electric dipole operator with the spin-position operator is significant (28% in amplitude in the case of iron). We obtain a sum rule relating this term to the spin magnetic moment of the p states. In alpha-LiIO3 we recover the expected angular dependence of the XNCD spectra

Ocean current connectivity propelling the secondary spread of a marine invasive comb jelly across western Eurasia

Aim: Invasive species are of increasing global concern. Nevertheless, the mechanisms driving furtherdistribution after the initial establishment of non-native species remain largely unresolved, especiallyin marine systems. Ocean currents can be a major driver governing range occupancy, but this hasnot been accounted for in most invasion ecology studies so far. We investigate how well initialestablishment areas are interconnected to later occupancy regions to test for the potential role ofocean currents driving secondary spread dynamics in order to infer invasion corridors and thesource–sink dynamics of a non-native holoplanktonic biological probe species on a continental scale.Location: Western Eurasia.Time period: 1980s–2016.Major taxa studied: ‘Comb jelly’ Mnemiopsis leidyi.Methods: Based on 12,400 geo-referenced occurrence data, we reconstruct the invasion historyof M. leidyi in western Eurasia. We model ocean currents and calculate their stability to match thetemporal and spatial spread dynamics with large-scale connectivity patterns via ocean currents.Additionally, genetic markers are used to test the predicted connectivity between subpopulations.Results: Ocean currents can explain secondary spread dynamics, matching observed range expansionsand the timing of first occurrence of our holoplanktonic non-native biological probe species,leading to invasion corridors in western Eurasia. In northern Europe, regional extinctions after coldwinters were followed by rapid recolonizations at a speed of up to 2,000 km per season. SourceJASPERS ET AL. | 815areas hosting year-round populations in highly interconnected regions can re-seed genotypes overlarge distances after local extinctions.Main conclusions: Although the release of ballast water from container ships may contribute tothe dispersal of non-native species, our results highlight the importance of ocean currents drivingsecondary spread dynamics. Highly interconnected areas hosting invasive species are crucial forsecondary spread dynamics on a continental scale. Invasion risk assessments should considerlarge-scale connectivity patterns and the potential source regions of non-native marine species