Exercise combined with artificial gravity and exercise only countermeasures prevent organ and blood vessel morpholgical changes induced by 55 days HDT bedrest.

Background: Changes in blood vessel properties have been identified with confinement, spaceflight, bedrest, and dry immersion. Subsequently, it was suspected that other organs may also be affected in these extreme environments. The purposes of the current study were to determine the effects of head-down bedrest (HDT) on cardiovascular and organ measurements made using ultrasound imaging similar to that currently available on the International Space Station, and to evaluate the efficacy of two different countermeasure protocols in preventing any observed changes in the ultrasound measurements with HDT.

Liver tissue changes during and post 6-month spaceflight as measured by ultrasound radio frequency signal processing.

Background: Analysis of ultrasound radio frequency (RF) signals allows for the determination of the index of reflectivity (IR), which is a new measure that is dependent on tissue properties. Previous work has shown differences in the IR of the carotid artery wall with long-duration spaceflight; therefore, it was hypothesized that liver tissue would also show differences in this measure with spaceflight.

Methods: The RF signal of a liver tissue region of interest (ROI) was displayed and processed along six different lines covering a surface of approximately 2 cm × 2 cm.

4 days in dry immersion increases arterial wall response to ultrasound wave as measured using radio-frequency signal, comparison with spaceflight data.

Recent studies have reported a significant increase in common carotid artery (CCA) intima media thickness, wall stiffness and reflectivity to ultrasound, in astronauts, after six months of spaceflight. The hypothesis was that 4 days in dry immersion (subjects under bags of water) will be sufficient to change the CCA wall reflectivity to ultrasound similar to what observed after spaceflight. Such response would be quantified using the amplitude of the ultrasound signal returned to the probe by the target concerned.

Numerical modeling and observations of seismo-acoustic waves propagating as modes in a fluid-solid waveguide.

This paper discusses the nature of the low-frequency seismo-acoustic waves generated by submarine earthquakes in the ocean. In a finite-depth homogeneous ocean over a semi-infinite solid crust, the derivation of the acoustic equations shows that waves propagate as modes. The waves propagating with the speed of sound in water (T waves) are preceded by waves with frequencies below the Airy phase.

Reduced Regional Cerebral Blood Flow Measured by Tc-Hexamethyl Propylene Amine Oxime Single-Photon Emission Computed Tomography in Microgravity Simulated by 5-Day Dry Immersion.

Microgravity induces a cephalad fluid shift that is responsible for cephalic venous stasis that may increase intracranial pressure (ICP) in astronauts. However, the effects of microgravity on regional cerebral blood flow (rCBF) are not known. We therefore investigated changes in rCBF in a 5-day dry immersion (DI) model.

Pilot Study of an e-Cohort to Monitor Adverse Event for Patient with Hip Prostheses from Clinical Data Warehouse.

Hip arthroplasty represents a large proportion of orthopaedic activity, constantly increasing. Automating monitoring from clinical data warehouses is an opportunity to dynamically monitor devices and patient outcomes allowing improve clinical practices. Our objective was to assess quantitative and qualitative concordance between claim data and device supply data in order to create an e-cohort of patients undergoing a hip replacement.

Implementing a personalized pharmaceutical plan in kidney or liver transplant patients: study protocol for a stepped-wedge cluster randomized trial (GRePH).

Background: Nowadays, the main challenge of transplantation is the improvement of long-term care, aiming at reducing treatment-related complications and at decreasing rejection rates. Patients' adherence to both treatment and hygienic-dietary measures is mandatory to achieve these objectives. Adherence to immunosuppressive drugs is estimated to be only 70%.

4 Day in dry immersion reproduces partially the aging effect on the arteries as observed during 6 month spaceflight or confinement.

The objectives of this study were to determine whether 4 days of dry immersion (DI) induced similar arterial aging as spaceflight and to test the impact of thigh cuffs. Eighteen subjects underwent DI; nine wore thigh cuffs. Cardiac and arterial targets were assessed by ultrasound.

Thigh Cuff Effects on Venous Flow Redistribution During 4 Days in Dry Immersion.

The objective was to quantify the venous redistribution during a 4-d dry immersion (DI) and evaluate the effect of thigh cuffs. The study included nine control (Co) and nine subjects wearing thigh cuffs during the daytime (CU). Ultrasound measures were performed Pre-DI, on day 4 AM (D4 AM) and D4 PM: left ventricle stroke volume and ejection fraction (SV, EF), jugular vein volume (JVvol), portal vein diameter (PV), and middle cerebral vein velocity (MCVv).

Low-level HIV viremia is associated with low antiretroviral prescription refill rates and social deprivation.

Optimal management of patients experiencing persistent low-level viremia (LLV) remains challenging and poorly understood. This study aimed to assess the association between poor antiretroviral treatment (ARV) adherence and persistent LLV. ADHELOW is a sub-study of the ECHEC cohort comprising HIV-infected adults with virological failure (viral load>50 copies/mL).

Three-dimensional modeling of earthquake generated acoustic waves in the ocean in simplified configurations.

The low-frequency (4-40 Hz) acoustic waves generated by undersea earthquakes are of great importance to monitor the low-level seismic activity associated with seafloor spreading ridges. To better understand the near-source interaction of seismic waves with the seafloor and the resulting generation of low-frequency acoustic waves, the wave propagation in a solid medium (the Earth's crust) and in the overlaying fluid medium (the ocean) were jointly simulated using a three-dimensional (3D) spectral finite-element code (SPECFEM3D). Due to numerical limitations of 3D simulations, the focus was on simple model configurations with a 1 Hz source located below a Gaussian seamount or ridge.

Effects of exercise countermeasure on myocardial contractility measured by 4D speckle tracking during a 21-day head-down bed rest.

Objective: To evaluate functional myocardial contractility after 21 days of head-down bed rest (HDBR) in sedentary control (CON) or with a resistive vibration exercise (RVE) countermeasure (CM) applied, by using 4D echocardiographic (4D echo) imaging and speckle tracking strain quantification.

Methods: Twelve volunteers were enrolled in a crossover HDBR design, and 4D echo was performed in supine position (REST) at BDC-2 and at R + 2, and in - 6° HDT at day 18, and during the first and the last minute of the 80° head-up step of tilt test performed at both BDC-2 and R + 2. Radial (Rad-Str), longitudinal (Lg-Str) and twist (Tw-Str) strains were measured by 4D speckle tracking, as well as left ventricle diastolic volume (LVDV) and mass (LVmass).

Spherical wave reflection in layered media with rough interfaces: Three-dimensional modeling.

In the context of sediment characterization, layer interface roughnesses may be responsible for sound-speed profile measurement uncertainties. To study the roughness influence, a three-dimensional (3D) modeling of a layered seafloor with rough interfaces is necessary. Although roughness scattering has an abundant literature, 3D modeling of spherical wave reflection on rough interfaces is generally limited to a single interface (using Kirchhoff-Helmholtz integral) or computationally expensive techniques (finite difference or finite element method).

The outer membrane porin OmpW of Acinetobacter baumannii is involved in iron uptake and colistin binding.

This study was undertaken to characterize functions of the outer membrane protein OmpW, which potentially contributes to the development of colistin- and imipenem-resistance in Acinetobacter baumannii. Reconstitution of OmpW in artificial lipid bilayers showed that it forms small channels (23 pS in 1 m KCl) and markedly interacts with iron and colistin, but not with imipenem. In vivo, (55) Fe uptake assays comparing the behaviours of ΔompW mutant and wild-type strains confirmed a role for OmpW in A.

Cellular organization of siderophore biosynthesis in Pseudomonas aeruginosa: Evidence for siderosomes.

Pyoverdine I (PVDI) and pyochelin (PCH) are the two major siderophores produced by Pseudomonas aeruginosa PAO1 to import iron. The biochemistry of the biosynthesis of these two siderophores has been described in detail in the literature over recent years. PVDI assembly requires the coordinated action of seven cytoplasmic enzymes and is followed by a periplasmic maturation before secretion of the siderophore into the extracellular medium by the efflux system PvdRT-OpmQ.

A cell biological view of the siderophore pyochelin iron uptake pathway in Pseudomonas aeruginosa.

Pyochelin (PCH) is a siderophore produced and secreted by Pseudomonas aeruginosa for iron capture. Using (55) Fe uptake and binding assays, we showed that PCH-Fe uptake in P. aeruginosa involves, in addition to the highly studied outer membrane transporter FptA, the inner membrane permease FptX, which recognizes PCH-(55) Fe with an affinity of 0.

Image source detection for geoacoustic inversion by the Teager-Kaiser energy operator.

This letter presents an improvement of the image source method for geoacoustic inversion. The algorithm is based on the Teager-Kaiser energy operator which amplifies the discontinuities in signals while the soft transitions are reduced. This property is exploited for accurate detection of time arrivals and thus for location of the image sources.

Deciphering protein dynamics of the siderophore pyoverdine pathway in Pseudomonas aeruginosa.

Pseudomonas aeruginosa produces the siderophore, pyoverdine (PVD), to obtain iron. Siderophore pathways involve complex mechanisms, and the machineries responsible for biosynthesis, secretion and uptake of the ferri-siderophore span both membranes of Gram-negative bacteria. Most proteins involved in the PVD pathway have been identified and characterized but the way the system functions as a whole remains unknown.

T-wave generation and propagation: a comparison between data and spectral element modeling.

T-waves are underwater acoustic waves generated by earthquakes. Modeling of their generation and propagation is a challenging problem. Using a spectral element code-SPECFEM2D, this paper presents the first realistic simulations of T-waves taking into account major aspects of this phenomenon: The radiation pattern of the source, the propagation of seismic waves in the crust, the seismic to acoustic conversion on a non-planar seafloor, and the propagation of acoustic waves in the water column.

Range dependent sediment sound speed profile measurements using the image source method.

This paper presents a range dependent sediment sound speed profile measurement obtained using the image source method. This technique is based on the analysis of the seafloor reflected acoustic wave as a collection of image sources which positions are linked with the thick-nesses and the sound speed of the sediment stack. The data used were acquired by the NURC in 2009 during the Clutter09 experiment.

Cell-cell contacts confine public goods diffusion inside Pseudomonas aeruginosa clonal microcolonies.

The maintenance of cooperation in populations where public goods are equally accessible to all but inflict a fitness cost on individual producers is a long-standing puzzle of evolutionary biology. An example of such a scenario is the secretion of siderophores by bacteria into their environment to fetch soluble iron. In a planktonic culture, these molecules diffuse rapidly, such that the same concentration is experienced by all bacteria.

Fate of ferrisiderophores after import across bacterial outer membranes: different iron release strategies are observed in the cytoplasm or periplasm depending on the siderophore pathways.

Siderophore production and utilization is one of the major strategies deployed by bacteria to get access to iron, a key nutrient for bacterial growth. The biological function of siderophores is to solubilize iron in the bacterial environment and to shuttle it back to the cytoplasm of the microorganisms. This uptake process for Gram-negative species involves TonB-dependent transporters for translocation across the outer membranes.

Pyoverdine biosynthesis and secretion in Pseudomonas aeruginosa: implications for metal homeostasis.

Pyoverdines are siderophores produced by fluorescent Pseudomonads to acquire iron. At least 60 different pyoverdines produced by diverse strains have been chemically characterized. They all consist of a dihydroquinoline-type chromophore linked to a peptide.