Biomedical subjects

P Lagrange

Publications and source records attributed to P Lagrange.

At least 19 recordsLinked to original sources

PubMed2006

[Automated RNA amplification for the rapid identification of Mycobacterium tuberculosis complex in respiratory specimens].

Rapid and sensitive detection of Mycobacterium tuberculosis complex (MTB) directly on clinical respiratory specimens is essential for a correct management of patients suspected of tuberculosis. For this purpose PCR-based kits are available to detect MTB in respiratory specimen but most of them need at least 4 hours to be completed. New methods, based on TRC method (TRC: Transcription Reverse transcription Concerted--TRCRapid M. Tuberculosis--Tosoh Bioscience, Tokyo, Japon) and dedicated monitor have been developed. A new kit (TRC Rapid M. tuberculosis and Real-time monitor TRCRapid-160, Tosoh Corporation, Japan) enabling one step amplification and real-time detection of MTB 16S rRNA by a combination of intercalative dye oxazole yellow-linked DNA probe and isothermal RNA amplification directly on respiratory specimens has been tested in our laboratory. 319 respiratory specimens were tested in this preliminary study and results were compared to smear and culture. Fourteen had a positive culture for MTB. Among theses samples, smear was positive in 11 cases (78.6%) and TRC process was positive in 8 cases (57.1%). Overall sensitivity of TRC compared to smear positive samples is 73%. Theses first results demonstrated that a rapid identification of MTB was possible (less than 2 processing hours for 14 specimens and about 1 hour for 1 specimen) in most cases of smear positive samples using ready to use reagents for real time detection of MTB rRNA in clinical samples. New pretreatment and extraction reagents kits to increase the stability of the sputum RNA and the extraction efficiency are now tested in our laboratory.

Automation↗

PubMed2006

Scanning tunneling spectroscopy on the novel superconductor CaC6.

We present scanning tunneling microscopy and spectroscopy of the newly discovered superconductor CaC6. The tunneling conductance spectra, measured between 3 and 15 K, show a clear superconducting gap in the quasiparticle density of states. The gap function extracted from the spectra is in good agreement with the conventional BCS theory with Delta0=1.6+/-0.2 meV. The possibility of gap anisotropy and two-gap superconductivity is also discussed. In a magnetic field, direct imaging of the vortices allows us to deduce a coherence length in the ab plane xiab approximately 33 nm.

Journal Article↗

PubMed2006

Experimental evidence of s-wave superconductivity in bulk CaC6.

The temperature dependence of the in-plane magnetic penetration depth, lambda(ab)(T), has been measured in a c-axis oriented polycrystalline CaC(6) bulk sample using a high-resolution mutual inductance technique. A clear exponential behavior of lambda(ab)(T) has been observed at low temperatures, strongly suggesting isotropic s-wave pairing. Data fit using the standard BCS theory yields lambda(ab)(0) = (720 +/- 80) A and delta(0) = (1.79 +/- 0.08) meV. The ratio 2delta(0)/k(B)T(c) = (3.6 +/- 0.2) gives indication for a weakly coupled superconductor.

Journal Article↗

PubMed2005

[Antiviral vaccination and respiratory mucosal immunity: still disappointing results from a seductive idea].

Mucosal surfaces of the respiratory tract represent a major portal of entry for most human viruses and a critical component of the mammalian immunologic repertoire. The major antibody isotype in external secretions is secretory immunoglobin A (S-IgA). The major effector cells in mucosal surfaces, however, are not IgA B cells, but T lymphocytes, which may account for up to 80% of the mucosal lymphoid cell population. Mucosal immunoprophylaxis is theoretically an important approach to control infections acquired through these portals. Passive antibodies can protect against mucosal viral infections, as shown for respiratory syncytial virus, but very high quantities of passive antibodies are needed to restrict virus replication on mucosal surface. Factors likely to induce mucosal antibody and cell-mediated immune responses include oral or respiratory routes of immunization and active (effectively replicating) vaccine agents. Very few antiviral vaccines have been developed to protect the mucosal surface of the respiratory tract, and only an attenuated influenza virus vaccine uses the nasal route. Other vaccines, approved for parenteral use, have been administered experimentally by the nasal route; these include active (replicating) and inactive (nonreplicating) vaccines. By this route they induce only a moderate local mucosal response. Neither the development of mucosal immunity nor the administration of vaccines via the mucosal route is essential for control or prevention of most respiratory viral infections and diseases acquired through the respiratory tract. Nonetheless, the example of the live attenuated intranasal influenza vaccine, which induces both systemic and local immune response, is promising for the future of mucosal immunization against respiratory viral infections.

Humans↗

PubMed2005

Superconductivity of bulk CaC6.

We have obtained bulk samples of the graphite intercalation compound, CaC6, by a novel method of synthesis from highly oriented pyrolytic graphite. The crystal structure has been completely determined showing that it is the only member of the MC6, metal-graphite compounds that has rhombohedral symmetry. We have clearly shown the occurrence of superconductivity in the bulk sample at 11.5 K, using magnetization measurements.

Journal Article↗

PubMed2001

Inhibition of rat brain microsomal cytochrome P450-dependent dealkylation activities by an oxidative stress.

There is increasing evidence that an oxidative stress not only alters cellular lipids and nucleic acids, but also numerous proteins. This oxidation results in alterations of some cellular functions, either by reversible modifications allowing a post-transcriptional regulation of enzyme activities or receptor affinities, or by irreversible modifications of the protein, triggering its inactivation and destruction. In the present work, we examined the effects of an experimental oxidative stress on rat brain microsomal cytochrome P450-dependent dealkylation activities. For that purpose, superoxide anions were produced either by the NADPH-dependent redox cycling of a quinine, menadione, or by the addition of apomorphine, which produces by autoxidation both superoxide anions and apomorphine-derived quinones. The inhibition of brain cytochrome P450-dependent alkoxyresorufin O-dealkylase activities was dependent on both menadione or apomorphine concentrations. Simultaneously, an increase of microsomal carbonyl groups was recorded. Immunoblotting characterization of brain microsomal oxidized protein was carried out, using antibodies raised against 2,4-dinitrophenylhydrazine as a reagent of protein carbonyl groups, and a revelation by a chemiluminescence method. We observed an increase in cerebral CYP1A protein oxidation, related to menadione concentration, suggesting that oxidation of cytochrome P450 protein may result in its catalytic inactivation.

Journal Article↗

PubMed2001

[Atrial flutter: a possible early sign of acute rejection in heart transplantation. A case report].

The authors report the case of a cardiac transplant patient with a recurrence of atrial flutter two months after electrical cardioversion and despite long-term preventive treatment with amiodarone. Early investigation for signs of rejection with 4 endomyocardial biopsies was negative. Aggravation of the haemodynamic status due to flutter with a rapid ventricular response led to an attempted radio-frequency ablation. Endocavitary mapping confirmed persistence of sinus activity in the native atrium and the presence of a circuit of type I isthmic flutter (anticlockwise circuit) in the donor atrium. Ablation by radio-frequency in the same procedure was successful. A fifth myocardial biopsy the same day finally confirmed stage 3A acute rejection. No signs of recurrent rejection or arrhythmia have been observed after 24 months' follow-up in this patient. This preliminary experience confirms the need to look for graft rejection by repeated myocardial biopsies in cardiac transplant, patients with atrial flutter and the efficacy of radio-frequency ablation in cases of resistance to conventional therapy.

Atrial Flutter↗

PubMed2001

Diagnostic value of a nested polymerase chain reaction assay on peripheral blood mononuclear cells from patients with pulmonary and extra-pulmonary tuberculosis.

SETTING: Saint Louis Hospital, Paris, France. OBJECTIVE: To determine the clinical relevance of detection of Mycobacterium tuberculosis DNA by nested polymerase chain reaction (PCR) in peripheral blood mononuclear cells (PBMCs) in the rapid diagnosis of tuberculosis. DESIGN: Single-centre prospective case study of 90 hospitalised patients and 50 healthy subjects or blood donors from 1 January to 30 June 1998. RESULTS: Twenty-three patients were diagnosed with tuberculosis (26.7%); 20 tuberculosis patients were culture-positive, with seven smear-positive for acid-fast bacilli. Sensitivity of smear, culture and nested PCR was 30.4 (7/23), 87 (20/23) and 30.4% (7/23), respectively. The specificity of smear and culture was 100%, and the specificity of the nested PCR was 96% in the healthy subjects. However, the specificity decreased to 83.6% in the hospitalised patients, with 11 nested PCR-positive patients without a diagnosis of tuberculosis. The sensitivity of the nested PCR was low in pulmonary tuberculosis (22.2%), but increased in pulmonary/extra-pulmonary tuberculosis (50%), extra-pulmonary tuberculosis (33%), and disseminated tuberculosis (33%). CONCLUSION: The use of a nested PCR assay on PBMC may pose problems for the rapid diagnosis of tuberculosis with regard to low sensitivity and specificity. However, further studies are needed to confirm this technique as an alternative test for the diagnosis of paucibacillary forms of tuberculosis.

Adult↗

PubMed2000

[Ventricular tachycardia by branch to branch re-entry. Familial case with Steinert's disease].

Ventricular tachycardia by branch to branch reentry is a rare arrhythmia. It occurs in cardiomyopathies associated with conduction defects. During tachycardia a His potential precedes each QRS complex which usually has a left bundle branch block appearance. The authors report two familial cases of ventricular branch to branch tachycardia (son and mother) without cardiomyopathy. The diagnosis of Steinert's disease was made post-mortem in these two patients. In cases of branch to branch ventricular tachycardia, the diagnosis of myotonic dystrophy should be excluded. Conversely, endocavitary electrophysiological investigation with ventricular stimulation should be proposed for symptomatic patients (dizzy spells, syncope) to diagnose branch to branch ventricular tachycardia, even in cases with conduction defects which could also explain the symptoms.

Adult↗

PubMed2000

[Radon and domestic exposure].

Radon is a noble gas derived from the decay of radium, which itself is a decay product of uranium. The decay products of radon can collect electrostatically on dust particles in the air and, if these particles are inhaled and attach to bronchial epithelium, produce a high local radiation dose. Alpha particles can induce DNA double-strand breaks and the development of cancer. A causal relation between lung cancer and radon exposure and its progeny has been demonstrated in epidemiological studies of miners. Radon exposure became a public health issue almost 15 years ago. Most radon exposure occurs indoors, predominantly in the home. There is however, a wide range of radon concentration values in different countries. The highest level occurs in areas with granite and permeable soils. The risk for smoking, the leading cause of lung cancer, is far greater than for radon, the second leading cause. The estimates obtained from case-control studies of indoor radon are very contradictory. Scientific knowledge of effects of low levels of exposure to radon and the role of cigarette smoking, as a combined factor, must be studied. Smoking and radon probably interact in a multiplicative fashion.

Air Movements↗

PubMed1999

[A rare cause of sudden death in young adults with "normal" heart: the Brugada syndrome].

BACKGROUND: Brugada syndrome is a rare condition causing sudden death in young adults due to unexpected sudden-onset ventricular fibrillation. Diagnosis is based on the presence of an ST depression in the anteroseptal territory and a right branch block. No underlying dysrhythmic condition or arrhythmogenic heart disease can be detected. CASE REPORT: A 15-year old boy with an uneventful past history experienced cardiocirculatory failure due to ventricular fibrillation during a sports competition. Cardiac arrest developed and resuscitation was initially successful but death ensued due to cerebral anoxia. Characteristic electrocardiographic signs and the presence of similar anomalies in a brother and an aunt led to the diagnosis of Brugada syndrome. DISCUSSION: Brugada syndrome is a recently discovered hereditary condition with a probably underestimated prevalence. Systematic family studies have demonstrated autosomal dominant inheritance. The characteristic electrocardiographic anomalies can be transitory and may be unmasked by sensitivization tests. The only currently effective treatment is the implantable defibrillator programmed to prevent sudden death by ventricular fibrillation.

Adolescent↗

PubMed1999

Transendothelial permeability changes induced by free radicals in an in vitro model of the blood-brain barrier.

In the present study, we investigated the changes in blood-brain barrier (BBB) permeability following brain endothelial cell exposure to different xenobiotics able to promote free radical generation during their metabolism. Our in vitro BBB model consisted of confluent monolayers of immortalized rat brain capillary endothelial cells (RBE4) grown on collagen-coated filters in the presence of C6 glioma cells grown in the lower compartment. We have recently shown that a range of xenobiotics, including menadione, nitrofurazone, and methylviologen (paraquat) may undergo monoelectronic redox cycling in isolated brain capillaries, giving rise to reactive oxygen species. In this study, addition of 100 microM menadione to the culture medium for 30 min significantly increased the permeability of endothelial cell monolayers to radiolabeled sucrose. The effect on endothelial permeability induced by menadione was dose-dependent and reversible. These permeability changes preceded the onset of cell death, as assessed by the Trypan blue exclusion method. Pre-incubation with superoxide dismutase and catalase blocked changes in sucrose permeability to control levels in a dose-dependent manner, suggesting the involvement of reactive oxygen species in menadione-induced BBB opening.

Animals↗

PubMed1999

[Radiofrequency ablation in auricular flutter. Predictive factors of primary success and medium term results].

Ninety-one consecutive patients underwent radiofrequency ablation of chronic or paroxysmal atrial flutter. The average age of the patients was 66. There was a previous history of atrial fibrillation in 38% of cases and of cardiac surgery in 14.3% of cases. The primary success rate was 79% (92% in cases of common flutter). The predictive factors of success were the type of flutter (p < 0.001), left ventricular (p < 0.01) and left atrial dimensions (p < 0.01) at echocardiography. The length of the cavo-tricuspid isthmus measured by echocardiography had no influence on the initial result but, in primary success, did affect the parameters of the procedure (duration and number of applications of radiofrequency energy). After an average of 11 +/- 2 months, sinus rhythm was maintained in 67% of patients. There were recurrences of flutter in 27.5% of cases and of atrial fibrillation in 5.5% of cases: 85% of these episodes occurred during the first six months after ablation. A second procedure was carried out in 12 patients for recurrence of flutter (92% primary success rate). After an average follow-up of 8.4 months, 4 patients had a recurrence and required a third procedure (100% success rate). In cases of failure of ablation, the rhythm was converted by a shock or atrial pacing: 47.3% of these patients remained in sinus rhythm with antiarrhythmic therapy with a 12 month follow-up. Radiofrequency ablation of atrial flutter is, therefore, a safe method, the difficulty of which is mainly related to anatomical factors: the medium-term results are better than those of other therapeutic methods.

Atrial Flutter↗

PubMed1999

[Evaluation of arrhythmic risk in coronary insufficiency].

Half of all deaths occurring in patients with heart failure are sudden deaths probably related to a malignant ventricular arrhythmia. The pathophysiological mechanisms of these arrhythmias are unclear, but left ventricular function, hypokalaemia accentuated by diuretics and treatments altering inotropism play a definite role. Because of the diversity of aetiologies generating heart failure, the multiplicity of fatal arrhythmias and the multifactorial origin of these arrhythmias, there is no formal marker for the risk of sudden death in patients with heart failure, at the present time. In addition to the NYHA classification and detection of episodes of syncope, assessment of these patients must be as complete as possible, at least including repeated evaluation of the ejection fraction, Holter ECG monitoring and detection of delayed ventricular potentials.

Arrhythmias, Cardiac↗

PubMed1998

[Lactobacillus acidophilus endocarditis].

BACKGROUND: Lactobacillus is a commensal germ found in the buccal cavity, the digestive tract and the vagina. Usually non-pathogenic except in case of dental caries, it can occasionally be the causal agent in severe endocarditis. CASE REPORT: A 70-year-old woman developed endocarditis on an aortic valve bioprosthesis. Lactobacillus acidophilus was isolated from blood cultures of the valve after surgery. COMMENTS: Forty-four cases of Lactobacillus endocarditis have been reported in the literature to date. Mortality is high (26%). The main difficulty in treatment is germ tolerance to penicillin and aminosides found in all cases. Cure requires high dose parenteral antibiotics and surgery in many cases (26%).

Aged↗

PubMed1998

[Peptostreptococcus magnus osteoarticular infections after orthopedic surgery. 14 cases and pathogenicity factors].

We report a retrospective study of 14 Peptostreptococcus magnus bone and joint infections, following orthopaedic prostheses or implantation of fixation devices, diagnosed in two Paris hospitals between 1992 and 1996. Five patients experienced a knee joint infection after anterior cruciate ligament reconstruction with 4 artificial grafts, and 9 caught joint or wound infections, after limb traumatic injuries or bone neoplastic ruptures involving femur, tibia, calcaneum and humerus, treated by arthroplasty or osteosynthesis with implantation of biomaterials. Septic arthritis was experienced one week to one year after reconstructive surgery, and had evolved for several months to years before etiologic diagnosis in 5 cases. Specimens of pus, tissues or removed implants produced numerous slow growing small colonies of Gram positive cocci arranged in clumps on culture media incubated in anaerobic atmosphere only. In 10 patients, the same organism was disclosed in several separate specimens. The identification of P. magnus was assessed by the enzyme profile (rapid ID 32A API strips), gaz liquid chromatography, catalase and coagulase production, resistance to novobiocin and Na polyanethol sulphonate. Antibiotic sensitivity testing performed by disc method was constant to penicillin G, amoxicillin, cefuroxime, cefoxitin, imipenem and pristinamycin with penicillin G MICs < 0.125 mg/l and metronidazole MICs < 1 mg/l. Erythromycin, clindamycin, rifampicin, tetracycline and fosfomycin were active against more than 70% of P. magnus. All patients were cured after a prolonged course of various antibiotics and surgical removal of the foreign material whenever possible. We studied in vitro binding of P. magnus with extracellular matrix proteins adsorbed onto biomaterials, by particle agglutination assays of latex beads coated with proteins. Eighty one% of strains bound to collagen, 69% to fibrinogen and 46% to fibronectin. Comparison of orthopaedic strains with strains of other infections and from skin showed a correlation between P. magnus from bone and joint infections and their fibrinogen binding ability (69% against 20%, p < 0.05).

Adolescent↗

PubMed1997

Prevalence of and risk factors for Clostridium difficile colonization at admission to an infectious diseases ward.

A study of 240 consecutive admissions to a single hospital ward over a 6-month period was conducted to determine the prevalence of and risk factors for Clostridium difficile colonization at admission. The prevalence rate of C. difficile colonization at admission was 13.3%. Seventy-four percent of the patients admitted to the ward were infected with human immunodeficiency virus (HIV). Multivariate analysis identified three risk factors for C. difficile colonization: clindamycin use (adjusted odds ratio [OR], 9.4; P < .001), penicillin use (adjusted OR, 3.9; P = .018), and a history of cytomegalovirus infection (adjusted OR, 4.2; P = .02). C. difficile colonization at admission to our infectious diseases ward was common. Antibiotic treatments received before admission were the main risk factors for C. difficile colonization. HIV infection per se was not associated with C. difficile colonization. It is interesting that there was an association between C. difficile colonization and a history of cytomegalovirus infection.

AIDS-Related Opportunistic Infections↗

PubMed1997

Cerebral tuberculosis in patients with the acquired immunodeficiency syndrome (AIDS). Report of 6 cases and review.

Cerebral tuberculosis (TB) was diagnosed in 6 (4%) of 156 HIV-infected patients with TB seen at our institution over 6 years. We describe here the clinical and radiologic features of these cases and of 15 others reported in the literature. Of the 21 patients, 59% were intravenous drug users. Presenting symptoms were fever (76%), confusion (52%), seizures (38%), and headache (38%). Fourteen patients (66%) had previous or active extracerebral TB at presentation. Cranial CT scan showed ring-(62%) or nodular-(24%) enhancing lesions or mixed forms (14%). Among the 12 patients who underwent a brain biopsy, bacteriologic evidence of TB was found in 9. Four patients (19%) died during hospitalization. Among the 17 others who received antituberculous therapy, only 1 developed neurologic sequelae. Five patients also received steroid therapy to control cerebral edema or paradoxical growth of the cerebral mass lesions. TB should be considered as a cause of cerebral mass lesions in HIV-infected patients, especially if tuberculous infection is suspected at other sites.

Acquired Immunodeficiency Syndrome↗