Ischémie mésentérique étendue associée à la prise excessive de naratriptan et de jus de pamplemousse

We reported the case of a 61-year-old woman, who has been hospitalized in ICU because of an extensive mesenteric ischaemia, involving the small bowel, secondary to a naratriptan overuse. This mesenteric ischaemia was complicated by multiple organ failure and was responsible for extensive small bowel resection and left colectomy. A concomitant abundant absorption of grapefruit juice, a well-known P450 inhibitor, may have enhanced this naratriptan toxicity. This case underscore that an abdominal pain occurring in the context of headache treatment may be related to a mesenteric ischaemia

A study of the virulence of Acinetobacter baumannii isolates in a mouse model of pneumonia

Date du colloque&nbsp;: 10/2008</p

Identification of pertinent indicators of virulence in a mouse model of Acinetobacter baumannii pneumonia

Date du colloque&nbsp;: 05/2009</p

A Universal Method to Generate Hyperpolarisation in Beams and Samples

Sizable hyperpolarisation, i.e. an imbalance of the occupation numbers of nuclear spins in a sample deviating from thermal equilibrium, is needed in various fields of science. For example, hyperpolarised tracers are utilised in magnetic resonance imaging in medicine (MRI) and polarised beams and targets are employed in nuclear physics to study the spin dependence of nuclear forces. Here we show that the quantum interference of transitions induced by radio-wave pumping with longitudinal and radial pulses are able to produce large polarisations at small magnetic fields. This method is easier than established methods, theoretically understood and experimentally proven for beams of metastable hydrogen atoms in the keV energy range. It should also work for a variety of samples at rest. Thus, this technique opens the door for a new generation of polarised tracers, possibly low-field MRI with better spatial resolution or the production of polarised fuel to increase the efficiency of fusion reactors by manipulating the involved cross sections.Comment: 22 pages, 9 figures, splitted into two parts: main paper and method

IgG subclass deficiency and vaccination antibody titers : a paediatric study

Date du colloque&nbsp;: 10/2008</p

The virulence variability of different Acinetobacter baumannii strains in experimental pneumonia

Our objective was to compare the virulence of 5 strains of Acinetobacter baumannii by using a mouse model of pneumonia. Methods Six-week old female C3H/HeN mice were used. The pneumonia was inducted by intra-tracheal inoculation of 5. 106 bacteria. Spontaneous outcome was evaluated by mortality, mice weight variations, and a clinical score. Bacterial counts in lungs, spleen and blood, and inflammatory response in lungs (dosages of tumor necrosis factor-alpha and macrophage inflammatory protein-2) were also measured. Lastly, a histological examination of lungs was performed for 3 strains, giving a histological score. Results Global mortality varied from 13% to 79% (P &lt; 10−4). Bacterial counts in lungs within the 4 days following inoculation varied significantly according to different strains. The evolution curves of bacterial counts were also different. There was a significant correlation between the clinical score and mortality (P &lt; 0.05) but not between bacterial counts in lungs and mortality. The increase of pro-inflammatory mediator production in lungs and the histological score also varied according to strains. Conclusions These results demonstrate the variability of the virulence between strains, and suggest that bacterial proliferation is not the only virulence factor responsible for the pathogenesis in A. baumannii pneumonia

Toward polarized antiprotons: Machine development for spin-filtering experiments

The paper describes the commissioning of the experimental equipment and the machine studies required for the first spin-filtering experiment with protons at a beam kinetic energy of $49.3\,$MeV in COSY. The implementation of a low-$\beta$ insertion made it possible to achieve beam lifetimes of $\tau_{\rm{b}}=8000\,$s in the presence of a dense polarized hydrogen storage-cell target of areal density $d_{\rm t}=(5.5\pm 0.2)\times 10^{13}\,\mathrm{atoms/cm^{2}}$. The developed techniques can be directly applied to antiproton machines and allow for the determination of the spin-dependent $\bar{p}p$ cross sections via spin filtering

Phase Measurement for Driven Spin Oscillations in a Storage Ring

This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in J\"ulich using a vector polarized, bunched $0.97\,\textrm{GeV/c}$ deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles

Spin tune mapping as a novel tool to probe the spin dynamics in storage rings

Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called \textit{spin tune mapping}, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 at the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than $2.8\mu$rad.Comment: 32 pages, 15 figures, 7 table

Phase locking the spin precession in a storage ring

This letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV/$c$ bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate ($\approx 121$ kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a one standard deviation range of $\sigma = 0.21$ rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles