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Biomedical subjects

C Boisson

Publications and source records attributed to C Boisson.

At least 19 recordsLinked to original sources
PubMed2006

[Analgesia after hip fracture repair in elderly patients: the effect of a continuous femoral nerve block: a prospective and randomised study].

INTRODUCTION: The usefulness of peripheral femoral nerve block for pain management after hip fracture has been established. This prospective and randomised study compared the analgesia effect of a continuous femoral nerve block (CF) versus two conventional analgesia procedures after hip fracture. PATIENTS AND METHODS: Patients. (n=62) scheduled for surgery under spinal anaesthesia were prospectively included. After surgery, analgesia (48 hours) was randomised: group FC (femoral catheter, anterior paravascular approach, initial bolus followed by continuous infusion of ropivacaine 0.2%), group P (iv 2 g propacetamol/6 hours), group M (sc morphine, 0.05 mg/kg per 4 hour). Intravenous morphine titration was performed, followed by subcutaneous (sc) morphine every 4 hours according to the VAS score. The primary end-point was the morphine requirements. Secondary end-points were VAS score, side effects, and mortality. RESULTS: Demographic data and surgical procedures were similar between groups. After morphine titration, the VAS pain score did not differ between groups. All patients in-group M received additional morphine. Morphine mean consumption was increased in CF group: 26 mg (5-42) versus P: 8 mg (3-12) (p=0.0001) or M: 19 mg (8-33) (p<0.006) while constipation was decreased in P group vs CF. Percentage of patients requiring no morphine was similar between P (n=6; 28%) and CF (n=6; 28%) and greater than M (n=0; 0%). Hospital discharge, cardiovascular or pulmonary complications and mortality after 6 months showed no statistical difference. CONCLUSION: Continuous femoral nerve block provided limited pain relief after hip fracture did not reduced side effects and induced an expensive cost.

Aged↗
PubMed2006

HESS observations of the galactic center region and their possible dark matter interpretation.

The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin.

Journal Article↗
PubMed2006

Fast variability of tera-electron volt gamma rays from the radio galaxy M87.

The detection of fast variations of the tera-electron volt (TeV) (10(12) eV) gamma-ray flux, on time scales of days, from the nearby radio galaxy M87 is reported. These variations are about 10 times as fast as those observed in any other wave band and imply a very compact emission region with a dimension similar to the Schwarzschild radius of the central black hole. We thus can exclude several other sites and processes of the gamma-ray production. The observations confirm that TeV gamma rays are emitted by extragalactic sources other than blazars, where jets are not relativistically beamed toward the observer.

Journal Article↗
PubMed2006

[Amniotic fluid embolism: successful evolution course of isolated disseminated intravascular coagulation and early biological diagnosis].

Amniotic embolism is a sudden, unexpected and devastating complication of pregnancy. The diagnosis is usually made on the basis of clinical presentation after excluding differential diagnosis or at autopsy in the event of death of the parturient. We need to develop simple, non-invasive, sensitive tests for a reliable and early diagnosis. We report the case of a 34-year-old woman, who presented soon after delivery, an isolated disseminated intravascular coagulation with severe haemorrhage, an haemostatic hysterectomy was required. A 3370 g child was delivered by caesarean section. The patient survived without sequelae. The diagnosis of amniotic embolism was established by the presence of amniotic cells in the maternal central venous blood as well as in the bronchoalveolar fluid.

Adult↗
PubMed2006

A low level of extragalactic background light as revealed by gamma-rays from blazars.

The diffuse extragalactic background light consists of the sum of the starlight emitted by galaxies through the history of the Universe, and it could also have an important contribution from the 'first stars', which may have formed before galaxy formation began. Direct measurements are difficult and not yet conclusive, owing to the large uncertainties caused by the bright foreground emission associated with zodiacal light. An alternative approach is to study the absorption features imprinted on the gamma-ray spectra of distant extragalactic objects by interactions of those photons with the background light photons. Here we report the discovery of gamma-ray emission from the blazars H 2356 - 309 and 1ES 1101 - 232, at redshifts z = 0.165 and z = 0.186, respectively. Their unexpectedly hard spectra provide an upper limit on the background light at optical/near-infrared wavelengths that appears to be very close to the lower limit given by the integrated light of resolved galaxies. The background flux at these wavelengths accordingly seems to be strongly dominated by the direct starlight from galaxies, thus excluding a large contribution from other sources-in particular from the first stars formed. This result also indicates that intergalactic space is more transparent to gamma-rays than previously thought.

Journal Article↗
PubMed2006

[Amniotic fluid embolism: a review].

Amniotic fluid embolism occurs rarely but is a leading cause of maternal mortality. It is a difficult and somewhat intangible diagnosis that warrants a high index of suspicion by physicians. AFE is an unpredictable, unpreventable, and, for the most part, an untreatable obstetric emergency. Management of this condition includes prompt recognition of the signs and symptoms, aggressive resuscitation efforts, and supportive therapy. Any delays in diagnosis and treatment can result in increased maternal and/or foetal impairment or death. Whereas once the invariable outcome of AFE was death of the mother, today the prognosis is somewhat brighter thanks to increased awareness of the syndrome and advances in intensive care medicine. No laboratory test is specific to attest the diagnosis and autopsy must to be realised in case of maternal death. Although non-specific, the diagnosis of AFE could be supported by the observation of amniotic fluid in the central venous blood as well as in the bronchoalveolar fluid. This easy and quick test will be helpful in decision-making. Prompt and aggressive supportive treatment is required to lessen an otherwise dismal outcome, which may include death and permanent disability. This article provides an account of the protean clinical features, pathogenesis, and principles involved in treatment.

Amniotic Fluid↗
PubMed2006

Discovery of very-high-energy gamma-rays from the Galactic Centre ridge.

The source of Galactic cosmic rays (with energies up to 10(15) eV) remains unclear, although it is widely believed that they originate in the shock waves of expanding supernova remnants. At present the best way to investigate their acceleration and propagation is by observing the gamma-rays produced when cosmic rays interact with interstellar gas. Here we report observations of an extended region of very-high-energy (> 10(11) eV) gamma-ray emission correlated spatially with a complex of giant molecular clouds in the central 200 parsecs of the Milky Way. The hardness of the gamma-ray spectrum and the conditions in those molecular clouds indicate that the cosmic rays giving rise to the gamma-rays are likely to be protons and nuclei rather than electrons. The energy associated with the cosmic rays could have come from a single supernova explosion around 10(4) years ago.

Journal Article↗
PubMed2005

Discovery of very high energy gamma rays associated with an x-ray binary.

X-ray binaries are composed of a normal star in orbit around a neutron star or stellar-mass black hole. Radio and x-ray observations have led to the presumption that some x-ray binaries called microquasars behave as scaled-down active galactic nuclei. Microquasars have resolved radio emission that is thought to arise from a relativistic outflow akin to active galactic nuclei jets, in which particles can be accelerated to large energies. Very high energy gamma-rays produced by the interactions of these particles have been observed from several active galactic nuclei. Using the High Energy Stereoscopic System, we find evidence for gamma-ray emission of >100 gigaelectron volts from a candidate microquasar, LS 5039, showing that particles are also accelerated to very high energies in these systems.

Journal Article↗
PubMed2005

A new population of very high energy gamma-ray sources in the Milky Way.

Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (HESS) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or x-ray counterpart and may be representative of a new class of "dark" nucleonic cosmic ray sources.

Journal Article↗
PubMed2004

High-energy particle acceleration in the shell of a supernova remnant.

A significant fraction of the energy density of the interstellar medium is in the form of high-energy charged particles (cosmic rays). The origin of these particles remains uncertain. Although it is generally accepted that the only sources capable of supplying the energy required to accelerate the bulk of Galactic cosmic rays are supernova explosions, and even though the mechanism of particle acceleration in expanding supernova remnant (SNR) shocks is thought to be well understood theoretically, unequivocal evidence for the production of high-energy particles in supernova shells has proven remarkably hard to find. Here we report on observations of the SNR RX J1713.7 - 3946 (G347.3 - 0.5), which was discovered by ROSAT in the X-ray spectrum and later claimed as a source of high-energy gamma-rays of TeV energies (1 TeV = 10(12) eV). We present a TeV gamma-ray image of the SNR: the spatially resolved remnant has a shell morphology similar to that seen in X-rays, which demonstrates that very-high-energy particles are accelerated there. The energy spectrum indicates efficient acceleration of charged particles to energies beyond 100 TeV, consistent with current ideas of particle acceleration in young SNR shocks.

Journal Article↗
PubMed2004

Amniotic fluid embolism during caesarean section.

Amniotic fluid embolism occurs rarely but is a leading cause of maternal mortality. A high index of clinical suspicion is necessary to make an early diagnosis to reduce morbidity and mortality. We report a non-fatal case of amniotic fluid embolism occurring during a caesarean section, with special emphasis on the mode of development and diagnosis. The initial presentation of this syndrome was a coagulopathy, followed by the usual complications of massive bleeding. Although non-specific, the diagnosis of amniotic fluid embolism was supported by the observation of amniotic fluid in the central venous blood as well as in the broncho-alveolar fluid.

Adult↗
PubMed2001

The continuous femoral nerve block catheter for postoperative analgesia: bacterial colonization, infectious rate and adverse effects.

UNLABELLED: We investigated the incidence of bacterial and vascular or neurological complications resulting from femoral nerve catheters used for postoperative analgesia. Patients requiring continuous femoral blockade were consecutively included. Using surgical aseptic procedure, 211 femoral nerve catheters were placed (short-beveled insulated needle, peripheral nerve stimulator). After 48 h, each catheter was removed and semiquantitative bacteriological cultures were performed on each distal catheter tip. Postoperative analgesia and antibiotics were standardized. All complications during the insertion of the catheters and postoperatively (after 48 h and 6 wk) were noted. Few initial complications with no immediate or delayed complications were noted (20 difficult insertions, 3 impossible injections, 3 ineffective catheters, and 12 vascular punctures). After 48 h, 208 catheters were analyzed; 57% had positive bacterial colonization (with a single organism in 53%). The most frequent organisms were Staphylococcus epidermidis (71%), Enterococcus (10%), and Klebsiella (4%). Neither cellulitis nor abscess occurred. Three transitory bacteremias likely related to the catheter occurred. After 6 wk, no septic complications were noted. One femoral paresthesia, partially recovered 1 yr later, was noted. We conclude that the risk of bacterial complications is small with femoral nerve catheters, although the rate of colonization is frequent. IMPLICATIONS: In this prospective study, continuous femoral nerve catheters were effective for postoperative analgesia but had a frequent rate of bacterial catheter colonization. We found no serious infections after short-term (2-day) infusion. Side effects were few, but one nerve injury occurred.

Adolescent↗
PubMed2001

Peutz-Jeghers families unlinked to STK11/LKB1 gene mutations are highly predisposed to primitive biliary adenocarcinoma.

INTRODUCTION: Germline mutations of the STK11/LKB1 tumour suppressor gene (19p13.3) are responsible for Peutz-Jeghers syndrome (PJS), a rare genetic disorder, which is dominantly inherited. In addition to the typical hamartomatous gastrointestinal polyps and perioral pigmented lesions, PJS is also associated with the development of tumours in various sites. No specific follow up has yet been evaluated for gene carriers. Furthermore, genetic heterogeneity has been reported, which makes genetic counselling difficult. METHODS: We report here the analysis of the STK11/LKB1 locus in a series of 34 PJS families, combining the search for mutations and rearrangements in the coding sequence, allele specific expression tests, and linkage studies. RESULTS: Germline deleterious mutation of the STK11/LKB1 gene were identified in 70% of cases. The hypothesis of a second PJS locus was reinforced and PJS families could be divided into two groups on the basis of the presence or absence of an identified STK11/LKB1 alteration. Analysis of clinical data indicates that the cancer associated risk is markedly different in the two groups. PJS patients with no identified STK11/LKB1 mutation are at major risk for proximal biliary adenocarcinoma, an infrequent tumour in the general population. CONCLUSION: Up to 30% of PJS patients are caused by mutation in an unidentified gene that confers high susceptibility to cancer development.

AMP-Activated Protein Kinase Kinases↗
PubMed2000

[Catheter-related nosocomial urinary infections in intensive care: physiopathology, epidemiology and prevention].

OBJECTIVES: Nosocomial urinary tract infections associated with bladders catheters are common and poorly understood. Data on the prevention of urinary tract infections are numerous and heterogenous. This update article aimed at analysing mechanisms, epidemiology and prevention of these infections. DATA SOURCES: We searched in the Medline database for articles in English or French, without limiting date of publication, using the following key words separely or in combination: urinary tract infection, nosocomial, catheter, infection urinaire, sonde urinaire. STUDY SELECTION: We considered all categories of articles. DATA EXTRACTION: Data on prevention of nosocomial urinary tract infections were analysed in depth. DATA SYNTHESIS: The data on pathogenesis of nosocomial urinary tract infections are still controversial. Various means for preventing urinary tract infections have been recommended: addition of antibacterial agents to urinary drainage system, inclusion of antimicrobial components into the catheter itself, antibiotic prophylaxis or closed sterile drainage system. Their efficiency in intensive therapy unit has not yet been fully assessed. The therapy of these infections is still under debate and requires additional prospective studies to establish the optimal management. CONCLUSION: Catheter-associated urinary tract infections reflect the general hygiene policy, starting with nurse practice patterns at catheter insertion, and ending with antibio-therapy prescriptions by medical staff.

Anti-Bacterial Agents↗