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Biomedical subjects

M Gisselbrecht

Publications and source records attributed to M Gisselbrecht.

At least 19 recordsLinked to original sources
PubMed2006

Photodouble ionization dynamics for fixed-in-space H2.

The Coulomb explosion of the hydrogen molecule, after absorption of a 76 eV photon, has been studied by momentum imaging the two electrons and the two protons. Absolute fully differential cross sections of high statistical quality are obtained. A subset of the overall data, namely, equal electron-energy sharing, is used to investigate the effects of molecular orientation on the photoelectron angular distribution. Departures from the first-order helium-like model are evident in detection geometries where electron-electron correlation is "frozen."

Journal Article↗
PubMed2005

The electronic structure of free water clusters probed by Auger electron spectroscopy.

(H2O)(N) clusters generated in a supersonic expansion source with N approximately 1000 were core ionized by synchrotron radiation, giving rise to core-level photoelectron and Auger electron spectra (AES), free from charging effects. The AES is interpreted as being intermediate between the molecular and solid water spectra showing broadened bands as well as a significant shoulder at high kinetic energy. Qualitative considerations as well as ab initio calculations explain this shoulder to be due to delocalized final states in which the two valence holes are mostly located at different water molecules. The ab initio calculations show that valence hole configurations with both valence holes at the core-ionized water molecule are admixed to these final states and give rise to their intensity in the AES. Density-functional investigations of model systems for the doubly ionized final states--the water dimer and a 20-molecule water cluster--were performed to analyze the localization of the two valence holes in the electronic ground states. Whereas these holes are preferentially located at the same water molecule in the dimer, they are delocalized in the cluster showing a preference of the holes for surface molecules. The calculated double-ionization potential of the cluster (22.1 eV) is in reasonable agreement with the low-energy limit of the delocalized hole shoulder in the AES.

Journal Article↗
PubMed2004

The size of neutral free clusters as manifested in the relative bulk-to-surface intensity in core level photoelectron spectroscopy.

A new approach for obtaining an estimate of the effective size of the free neutral clusters is proposed. The approach relies on an experimental measure of the surface and interior or "bulk" cluster atoms provided by the x-ray photoelectron spectroscopy and on a model for the attenuation of photoelectrons ejected from the bulk of the cluster as the result of the ionizing irradiation. The experimental part gives the ratio of the electron signal from the bulk cluster atoms to that from the cluster surface atoms for a wide range of cluster sizes and electron kinetic energies. The attenuated response of the bulk atoms is modeled using an exponential law with the cluster size and kinetic-energy-dependent electron escape depth as parameters. For the experimental size range, model-based calculations for Ar, Kr, and Xe clusters are presented. The cluster size estimates obtained from comparison of the model calculations and experimental results agree well with those determined from the parameters of the cluster creation process. The combination of experiment and modeling also makes it possible to estimate the effective escape depth for electron propagation in free clusters. For Ar, Kr, and Xe clusters of varying mean size, absolute determination of the surface and bulk electron binding energies of the core levels used in the experiments has also been made.

Journal Article↗
PubMed2004

[Acute pulmonary infections in elderly patients in institutions].

The high incidence of lower lung infections in elderly subjects in institutions is responsible for an increase in mortality both as the result of the infection itself and of the deterioration of pre-existing conditions. The multiple pathology of these elderly patients living in institutions necessitates particularly detailed diagnosis and management. While the pneumococcus remains the predominant organism the percentage of infections with staphylococci and Gram negative bacteria is higher than among younger subjects. The initial severity should be assessed by clinical and pathological criteria in the same way as the response to treatment. Transfer to hospital is often necessary. Among preventative measures anti-influenzal and anti-pneumococcal vaccines are recommended and reimbursed at 100%.

Acute Disease↗
PubMed2004

[Tuberculosis in elderly persons living in institutions].

INTRODUCTION: In industrialised countries the incidence of tuberculosis increases with age. STATE OF ART: Tuberculosis remains a current problem in the elderly and may be contracted in an institution. Elderly persons living in institutions account for four times more cases than the elderly living at home. Tuberculosis may present in all forms and situations but the clinical and radiological features may be atypical. Although tuberculin anergy may be found frequently in elderly patients the diagnosis relies on the same principles as in the younger patient. Mortality, even with treatment, is increased and rises with age. Several problems arise in institutions: the screening of sick residents and of subjects at risk as well as the screening of infected patients. PERSPECTIVES: A rigorous policy of prevention and surveillance should lead to a fall in the incidence of the disease in institutions CONCLUSIONS: This collection of data demonstrates that tuberculosis remains a real health problem in elderly subjects in institutions.

Aged↗
PubMed2003

[Tuberculosis in elderly persons living in institutions].

INTRODUCTION: In industrialised countries the incidence of tuberculosis increases with age. STATE OF ART: Tuberculosis remains a current problem in the elderly and may be contracted in an institution. Elderly persons living in institutions account for four times more cases than the elderly living at home. Tuberculosis may present in all forms and situations but the clinical and radiological features may be atypical. Although tuberculin anergy may be found frequently in elderly patients the diagnosis relies on the same principles as in the younger patient. Mortality, even with treatment, is increased and rises with age. Several problems arise in institutions: the screening of sick residents and of subjects at risk as well as the screening of infected patients. PERSPECTIVES: A rigorous policy of prevention and surveillance should lead to a fall in the incidence of the disease in institutions. CONCLUSIONS: This collection of data demonstrates that tuberculosis remains a real health problem in elderly subjects in institutions.

Aged↗
PubMed2002

[Acute pulmonary infections in elderly patients in institutions].

The high incidence of lower lung infections in elderly subjects in institutions is responsible for an increase in mortality both as the result of the infection itself and of the deterioration of pre-existing conditions. The multiple pathology of these elderly patients living in institutions necessitates particularly detailed diagnosis and management. While the pneumococcus remains the predominant organism the percentage of infections with staphylococci and Gram negative bacteria is higher than among younger subjects. The initial severity should be assessed by clinical and pathological criteria in the same way as the response to treatment. Transfer to hospital is often necessary. Among preventative measures anti-influenzal and anti-pneumococcal vaccines are recommended and reimbursed at 100%.

Acute Disease↗
PubMed2001

[Reduction in the number of lethal heroin overdoses in France since 1994. Focus on substitution treatments].

BACKGROUND: Since 1994-1995, rapid development of widely available substitution treatments has appeared to be a major healthcare step in heroin addiction. Currently approximately 60000 patients are taking daily maintenance doses of oral methadone and about 7200 are taking sublingual buprenorphine. In parallel with the expansion of these treatments, the number of lethal overdoses has fallen off regularly: 564 in 1994, 393 in 1996 and 143 in 1998 (-74.6% in 4 years). AIM OF THE STUDY: We searched for a correlation between the rise in the number of patients taking maintenance treatments and the decreased in recorded deaths due to heroin overdose. Other factors which may influence this decrease were also considered. RESULTS AND DISCUSSION: A linear correlation was found between the increasing number of patients on maintenance treatment (high-dose buprenorphine or methadone) and the decrease in fatal heroin overdoses in France between 1994 and 1998. The importance of this correlation must be modulated by the presence of other events such as political, social, healthcare and behavioral events concerning drug users.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[Vasculitis during human acquired immunodeficiency virus infection].

Vasculitis is among the dysimmunity-mediated disorders seen in patients infected with the human immunodeficiency virus (HIV). Several cases have been reported. The central and peripheral nervous systems were the main targets, although many other organs may be involved. There were wide variations in clinical presentation, clinico-pathologic patterns, and the stage of the HIV infection at vasculitis onset. Causes included drugs and infections, particularly some opportunistic infections. In some cases, the vasculitis seemed to be directly due to the HIV. The etiopathogenesis remains unclear and the treatment unstandardized. Four cases of systemic vasculitis in HIV-infected patients are reported herein. All four patients received the treatment recommended for hepatitis B virus-related polyarteritis nodosa, namely plasma exchange and antiretroviral drugs.

Anti-HIV Agents↗
PubMed1998

Spectroscopic Techniques using Synchrotron Radiation and Free-Electron and Conventional Lasers.

Considerable progress in the investigation of the electronic and vibrational properties of atoms, molecules, materials, surfaces and interfaces has been achieved by combining different photon sources of complementary characteristics. In this paper some experimental results obtained recently at LURE by using two synchronized sources, such as the IR free-electron laser (FEL) CLIO, the VUV storage ring FEL, synchrotron radiation and table lasers, are presented. Using CLIO synchronized with a YAG laser allows the investigation of the vibrational properties of adsorbed species by the non-linear optical technique of visible-IR sum (difference) frequency generation, as shown for the adsorption of hydrogen on platinum in the electrochemical environment. The second result reported here relates to the study of the intersubband stimulated emission in GaAs/GaAlAs quantum wells by pump-probe experiments using the two-colour configuration of CLIO. The combination of a mode-locked Ar(+) laser and synchrotron radiation has been used for investigations in a pump-probe arrangement of the ionization of Xe atoms via the resonant state Xe* 5p(5)5d [3/2](1). The final example is a time-resolved core-level spectroscopy study of photoexcited Si(111) 2 x 1 surfaces by using a combination of the naturally synchronized UV storage ring laser and synchrotron radiation.

Journal Article↗
PubMed1998

Incidence and predictors of major hemorrhagic complications from thrombolytic therapy in patients with massive pulmonary embolism.

PURPOSE: The risk factors for bleeding in patients receiving recombinant tissue-type plasminogen activator for massive pulmonary embolism are not known. PATIENTS AND METHODS: The hospital records of 132 consecutive patients who received recombinant tissue-type plasminogen activator for massive pulmonary embolism were retrospectively reviewed. Bleeding was estimated by using the bleeding severity index, a method previously validated in patients receiving anticoagulants. Multivariate stepwise logistic regression was used to identify independent risk factors for bleeding. Four other definitions of bleeding in large pulmonary embolism thrombolytic trials were also used, and the agreement among these criteria was assessed. RESULTS: According to the bleeding severity index, 33 patients (25%) had one or more major bleeding complications. Hemorrhage at the venous puncture site for angiography was the most frequent complication (15 patients, 11%). Major bleeding at the catheterization site was more common at the femoral site (14 of 63 patients = 22%) than at the brachial site (1 of 63 patients = 2%; P = 0.0004). The use of the five different bleeding definitions resulted in a variation in the major bleeding rate from 3% to 43%. The kappa coefficient varied from 0.07 to 0.84, indicating poor agreement between most of the classifications. CONCLUSION: The use of the femoral vein for pulmonary angiography was the only variable significantly associated with major bleeding. Most of the differences observed in the pulmonary embolism thrombolytic trials are likely related to the differences in the definition of bleeding rather than to the thrombolytic regimen.

Aged↗
PubMed1998

Human immunodeficiency virus-related vasculitis. Clinical presentation of and therapeutic approach to eight cases.

Vasculitides occurring during the course of human immunodeficiency virus (HIV) infection are heterogeneous in their clinical presentation, time of occurrence, histological findings and etiological factors. Some of them can be directly attributed to HIV infection and their treatment might require new therapeutic approaches, such as plasma exchanges, specific antiviral agents and/or vasodilators. We report 8 cases of vasculitis associated with HIV. Five of them met the classification criteria of polyarteritis nodosa and had symptoms compatible with microscopic polyangiitis. Etiological agents were not identified. Although hepatitis B virus, hepatitis C virus (HCV) and other viruses or opportunistic agents were detected in some patients, HCV was suspected of being the etiological factor in only 1 of them. Focusing on viral and immunological features, the possible mechanisms of vasculitis development in HIV+ patients are discussed. Long-term follow-up indicates a clear benefit of regimens including antiviral agents, vasodilators and plasma exchanges. No deterioration of AIDS status was observed with this treatment and no relapse was recorded.

Adult↗
PubMed1997

Pulmonary complications in toxic epidermal necrolysis: a prospective clinical study.

OBJECTIVE: To evaluate the incidence, clinical features, and prognosis of pulmonary complications associated with toxic epidermal necrolysis DESIGN: Prospective study. SETTING: Dermatology intensive care unit in Mondor Hospital, France. PATIENTS: 41 consecutive patients. INTERVENTIONS: On admission, then daily, respiratory evaluation was based on clinical examination, chest X-ray, and arterial blood gas analysis. When clinical symptoms, X-ray abnormalities, or hypoxemia [partial pressure of oxygen (PO2) < 80 mm Hg] were present, fiberoptic bronchoscopy was performed. RESULTS: 10 patients presented early manifestations: dyspnea (n = 10), bronchial hypersecretion (n = 7), marked hypoxemia (n = 10) (PO2 = 59 +/- 8 mm Hg). Chest X-ray was normal (n = 8) or showed interstitial infiltrates (n = 2). In these 10 patients, fiberoptic bronchoscopy demonstrated sloughing of bronchial epithelium in proximal airways. Delayed pulmonary complications occurred in 6 of these 10 patients from day 7 to day 15: pulmonary edema (n = 2), atelectasis (n = 1), bacterial pneumonitis (n = 4). Mechanical ventilation was required in 9 patients. A fatal outcome occurred in 7 patients. Seven patients did not develop early pulmonary manifestations (PO2 on admission 87 +/- 6 mm Hg) but only delayed pulmonary symptoms related to atelectasis (n = 1), pulmonary edema (n = 4), and bacterial pneumonitis (n = 3); bronchial epithelial detachment was not observed. None of them required mechanical ventilation and all recovered with appropriate therapy. CONCLUSIONS: "Specific" involvement of bronchial epithelium was noted in 27% of cases and must be suspected when dyspnea, bronchial hypersecretion, normal chest X-ray, and marked hypoxemia are present during the early stages of toxic epidermal necrosis. Bronchial injury seems to indicate a poor prognosis, as mechanical ventilation was required for most of these patients and was associated with a high mortality.

Adolescent↗
PubMed1997

[Comparison of efficacy and tolerability of a thrombolytic treatment with rt-PA in acute massive pulmonary embolism in the elderly and patients under 75 years of age].

BACKGROUND: Pulmonary embolism often occurs in elderly patients. However, clinical presentation and treatment of massive pulmonary embolism (PE) in the elderly have not been extensively investigated. We report the results of rt-PA bolus infusion in patients aged 75 years or more suffering from massive PE. METHODS: Fifty-four adult patients referred to our institution with symptoms suggestive of massive PE were included in a therapeutic trial of single-chain rt-PA. Patients with a Miller angiographic score of at least 20/34 were considered for entry into the study. Patients were divided into two groups according to their age. Clinical presentation at admission, resolution of scintigraphic vascular obstruction, death rate, hemorrhagic complications, recurrent pulmonary embolism and long-term follow-up were compared between both groups. RESULTS: Twenty-eight patients were less than 75 years old and 26 patients were aged 75 years or more. Clinical symptoms at admission were similar in both groups. The mean absolute improvement in the lung scan perfusion defect, the rate of major bleeding, and the long-term evolution were not statistically different between older and younger patients. CONCLUSION: Clinical presentation and tolerance of massive PE did not differ between elderly and non-elderly patients. Old age should not preclude thrombolytic therapy in massive PE, provided there are no other contraindications for thrombolytic treatment.

Acute Disease↗