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M Meunier

Publications and source records attributed to M Meunier.

At least 19 recordsLinked to original sources
PubMed2005

Diffusion coefficients of small gas molecules in amorphous cis-1,4-polybutadiene estimated by molecular dynamics simulations.

Molecular dynamics (MD) simulations were employed to estimate the diffusion coefficients of small gas molecules (Ar, O2, N2, CO2, and CH4) in amorphous cis-1,4-polybutadiene in the temperature range of 250-400 K. The VT diagram and solubility parameter of the amorphous polymer have been successfully reproduced using a full atomistic potential. Diffusion coefficients were calculated from long NPT MD runs (up to 3 ns) at temperature ranging from 250 up to 400 K. Calculated diffusion coefficients compare well with experimental data as well as previous published work, though a systematic overestimation is found due to the finite-size effect of the model. The influence of various physical and computational parameters on the results is discussed. The diffusion mechanism is examined at the different temperatures of study.

Journal Article↗
PubMed2005

A mediatorless biosensor for putrescine using multiwalled carbon nanotubes.

Poly(diallyldimethylammonium) chloride, having a capability of dispersing multiwalled carbon nanotubes (MWCNTs), permits the modification of electrode surfaces. Together with putrescine oxidase, a MWCNT modified glassy carbon electrode was constructed for the development of a mediatorless putrescine biosensor. Nanoscale "dendrites" of MWCNTs were reasoned to form a network, projecting outward from the electrode surface acting like bundled ultra-microelectrodes, thereby permitting access to the active site and facilitating direct electron transfer to the immobilized enzyme. Our biosensor was capable of efficiently monitoring the direct electroactivity of putrescine oxidase at the electrode surface. Direct electron transfer permits the detection of putrescine at negative potentials, circumventing the interference of endogenous ascorbic and uric acids, which often complicate the analysis of important compounds in plasma. Compared with the most common interfering species, such as spermine, spermidine, cadaverine, and histamine, a detection limit of 5 microM and a response 20 times greater were found for putrescine. Tests performed on plasma of cancerous mice demonstrated that the detection of putrescine could be carried out very quickly on mammalian plasma without previous purification.

Animals↗
PubMed2004

[New developments in breast imaging].

In 2004, breast cancer screening will be effective in France. This evolution has a strong impact on our mammographic practice that becomes a real mission of public health. Digital mammography, compared to screen-film mammography, provides the same results for the detection of breast cancer, computer-aided detection systems represent the most relevant application of this technology at this time. The setting up of a quality control will allow the introduction of this technology in screening during 2004. Percutaneous imaging-guided procedures are now currently used for the diagnosis of nonpalpable breast lesions and allow the selection of patients for surgery. These procedures have emphasized the need for a multidisciplinary approach of the patients. Indications of MRI have not changed because of its moderated specificity and no relevant development of interventional-guided procedures. Work on standardization of radiological reports and assessment categories goes on. This classification is already applied for mammography, and new classifications for lesions detected by ultrasound or MRI will be published by the American College of Radiology (Breast Imaging Reporting and Data System, 4th edition, available in 2003).

Aged↗
PubMed2003

In vivo breast tumor detection using transient elastography.

This paper presents first in vivo experiments for breast tumor detection using transient elastography. This technique has been developed for detection and quantitative mapping of hard lesions in soft tissues. It consists in following the propagation inside soft tissues of very low-frequency shear waves (approximately 60 Hz) generated by a vibrating system located at the body surface. Because transient shear waves propagate through the medium in less than 0.1 s, the shear propagation imaging is performed with an ultrafast echographic scanner able to reach frame rates up to 6000 Hz. The local shear wave speed is directly linked to the local shear Young's modulus of the medium. The shear elasticity map of the medium can then be computed using an inversion algorithm. In vivo experiments were conducted on 15 women who had palpable breast lesions. For clinical adaptability reasons, shear waves were generated by the surface of the ultrasound (US) imaging transducer itself, which was linked to a mechanical vibrator. Our preliminary in vivo results demonstrate the clinical applicability of the transient elastography technique for breast lesion detection.

Adenocarcinoma↗
PubMed2003

[Interventional radiology in nonpalpable lesions of the breast].

The increasing number of nonpalpable breast lesions found at screening mammography has induced the development of percutaneous imaging-guided procedures to reduce the number of surgical biopsies. After a description of the indications (classification of the American College of Radiology), the different types of sampling procedures (fine needle aspiration, core and large-core biopsies) will be described and the material used also. Depending on the type of breast lesions (mass, clustered microcalcifications), ultrasound--guided and stereotactic--guided biopsies will be explained. Clear information to the patients, efficient quality control and multidisciplinary approach are mandatory for the success of these percutaneous diagnostic procedures.

Biopsy, Fine-Needle↗
PubMed2002

Fine needle aspiration cytology versus percutaneous biopsy of nonpalpable breast lesions.

Fine needle aspiration (FNA) and core biopsy (CB) are efficient alternatives to surgical biopsy: FNA provides a sampling of cells and is very cost effective. The main limits are insufficient sampling rate and the impossibility to diagnose invasion. CB allows architectural description and the diagnosis of specific benign and malignant lesions, but is more expensive and time-consuming.

Biopsy, Needle↗
PubMed2001

[Severe cutaneous Streptococcus pyogenes infections in the child: results of a multicenter survey].

UNLABELLED: To assess pediatric cases of severe cutaneous infections due to Streptococcus pyogenes. Since the beginning of 1980, the incidence of cellulitis and necrotizing fasciitis due to S. pyogenes has increased in adults. Serotyping of obtained isolates are in most cases M1, M3 or M5 protein. PATIENTS AND METHOD: A retrospective (1990-2000) survey was carried out in pediatric hospital centers. RESULTS: Three cases of necrotizing fasciitis and 15 of cellulitis were observed. In 30% of the cases, vancella lesions were associated; in the other cases, minor wounds were the site of the infection. Bacteriologic diagnosis was made by local samples in 14 cases; blood cultures were positive in four cases. In 11 cases, initial intravenous treatment consisted of third generation cephalosporin, in six cases of penicillin M or G and in one case of fusidic acid. In the second time, penicillin M was perfused in the majority of the cases. Mean duration of intravenous antibiotics perfusion was 15 days. There were no sequelae or death in this survey. CONCLUSIONS: Despite this study had limited epidemiological characteristics, it confirms that these two infections are rare. The frequency is probably underestimated, due to the difficulty in performing a diagnosis. The major site of infection was the varicella lesion. These two infections are so similar that it is frequent to mistake one infection for the other. Nonsteroidal anti-inflammatory drugs and site of infections did not influence prognosis. The treatment of cellulitis is penicillinotherapy whereas in necrotizing fasciitis early major surgery is often correlated with the rate of survival.

Cellulitis↗
PubMed2000

Effects of RPR 118723, a novel antagonist at the glycine site of the NMDA receptor, in vitro.

RPR 118723 ((8-chloro-5-methyl-2,3-dioxo-1,4-dihydro-5H-indeno[1, 2-b]pyrazin-5-yl) acetic acid) was previously reported to exhibit potent affinity for the glycine site of the N-methyl-D-aspartate (NMDA) receptor-channel complex in the nanomolar range (K(i)=3.1+/-0. 8 nM). We now report on the effects of RPR 118723 in two functional tests reflecting the interaction between the glycine site and the NMDA receptor. First, RPR 118723 potently inhibited [3H]N-[1-(2-thienyl)cyclohexyl]-3,4-piperidine ([3H]TCP) binding in the presence of NMDA (IC(50)=3.5+/-0.4 nM). Second, RPR 118723 antagonized the NMDA-induced increase in [3H]dopamine release in mouse striatal slices (IC(50)=8.0+/-1.1 nM). In both experimental models, an excess of glycine reversed the effect of RPR 118723. These results show that RPR 118723 interferes functionally in the nanomolar range with the glycine site coupled to the NMDA receptor in vitro. The blockade of the glycine site with RPR 118723 may be useful for the therapy of the disorders linked to excessive NMDA stimulation.

Animals↗
PubMed2000

The anti-oxidant ebselen antagonizes the release of the apoptogenic factor cytochrome c induced by Fe2+/citrate in rat liver mitochondria.

We studied the effects of ebselen (a seleno-organic anti-oxidant), on the release of the apoptogenic factor, cytochrome c, in two different experimental situations damaging mitochondria: (1) Fe(2+)/citrate, known to induce lipid peroxidation consecutively to an oxidative stress; and (2) atractyloside, a ligand of the adenine nucleotide translocator. The effects of ebselen were compared to those of butylated hydroxytoluene (BHT, an inhibitor of lipid peroxidation), and cyclosporine A (CsA, a classical pore antagonist). Ebselen, like BHT, inhibited Fe(2+)/citrate-induced release of cytochrome c, whereas CsA was inactive. On the contrary, neither ebselen nor BHT inhibited atractyloside-induced release of cytochrome c, whereas CsA was potently active. The antioxidant properties of ebselen may protect mitochondria from the consequences of the release of cytochrome c. Thus, it is suggested that the neuroprotective effect of ebselen previously demonstrated in humans and in animals may be due, at least in part, to a mitochondrial protection.

Animals↗
PubMed2000

Diagnostic accuracy of sonography and combined sonographic assessment and sonographically guided cytology in nonpalpable solid breast lesions.

PURPOSE: The aim of this study was to assess the diagnostic accuracy of sonography alone and combined sonographic assessment and sonographically guided fine-needle aspiration cytology in solid, nonpalpable lesions of the breast. METHODS: We retrospectively evaluated the sonograms from a series of 174 consecutive nonpalpable masses that were cytologically diagnosed using fine-needle aspiration under sonographic guidance and then histologically verified through surgical excision. We examined the relationships between the findings from sonography, combined sonographic assessment and cytopathology, and histology. RESULTS: Histologically, 95 lesions (55%) were malignant and 79 (45%) were benign. The overall sensitivity of sonography alone for diagnosing cancer was 98. 9% (94 of 95 lesions), and the specificity was 45.6% (36 of 79 lesions). One (3%) of 37 masses considered at sonography to be benign was correctly diagnosed on cytologic examination to be cancer. By establishing the benign status of 11 of 13 masses that were indeterminate at sonography, cytology increased the specificity of the combined method (to 56.3%). Cytology appropriately suspected or confirmed malignancy in 79 (84%) of 94 carcinomas considered at sonography to be suspicious or malignant. CONCLUSIONS: In this study, sonography alone demonstrated a high sensitivity but limited specificity in evaluating nonpalpable breast masses. The addition of sonographically guided cytology substantially increased the specificity of the combined method without compromising sensitivity.

Adult↗
PubMed2000

Computerized ultrasound B-scan characterization of breast nodules.

The ability of computerized parameters to discriminate benign from malignant breast nodules from digitized ultrasonic acquisitions has been assessed. The images of 75 lesions, including 19 lesions proved to be malignant at histology and 56 found to be benign, were digitized and characterized by morphometric and texture parameters. The texture parameters, derived from first-order statistics, run-length matrices and co-occurrence matrices, were computed in the entire lesion and in a ring-shape region surrounding the contour of the lesion. The strongest features were found to be issued from the second region. Further investigations confirmed that the discriminant information was contained in the external part of the lesion and, to a lesser extent, in the neighboring tissue. A linear discriminant analysis using three features yielded a sensitivity of 94.7% for a specificity of 80.4% and the "leave-one-out" technique confirmed the results. Comparison with the classifications given by radiologists let us assume that information revealed by texture features is able to help the physician in reducing the number of unnecessary biopsies.

Breast Diseases↗
PubMed2000

[Lyme disease in Upper Normandy: report of a hospital survey].

This study presents the results of a hospital survey on Lyme disease in children living in upper Normandy, a region that is quite densely wooded (with 18% forest areas and woods). The aim of this survey was to assess the prevalence of this disease in children from the Seine-Maritime and L'Eure, hospitalized in pediatric wards in the Seine-Maritime department, which includes Rouen, Dieppe, Fécamp, Elbeuf, and Le Havre. Fifteen cases of Lyme disease were diagnosed between September 1988 and June 1997. The children (6 girls and 9 boys) were aged between 5 and 14 years old. Only 7 subjects showed primary symptoms, while secondary symptoms were observed in 12 children. In the study population, a high prevalence (11 out of the 15 children) of neurological disorders was found. The following secondary symptoms were noted: 5 cases of erythema migrans, 2 cases of non-malignant cutaneous lymphocytoma, and 4 cases which in fact had previously displayed primary clinical signs (3 subjects with erythema migrans and 1 subject with non-malignant cutaneous lymphocytoma); 7 cases of uni- or bilateral facial paralysis, the most frequent neurological manifestation with or without lymphocytic meningitis; 1 case of central vestibular syndrome with a hyperalgesic meningoradicular reaction in the vicinity of the tick bite; 1 case of peripheral radicular involvement and intense pain in the left lower limb; 4 cases of ocular disorders (3 diplopias, 1 bilateral conjunctivitis complicated by kerato-uveitis, 1 bilateral complete cecitis). Only 10 child had rheumatological symptoms, i.e., Lyme arthritis of the right knee. Treatment consisted of amoxicillin (10 children) administered at a dosage of 50 to 100 mg/kg/d over a period ranging from 10 days to 1 month, or ceftriaxone (7 children) at a dosage of 50 to 100 mg/kg/d administered intravenously over a period ranging from 8 days to 3 weeks. Two of the children received combined antibiotic therapy, and 5 subjects had adjunct corticotherapy.

Adolescent↗
PubMed1999

Riluzole series. Synthesis and in vivo "antiglutamate" activity of 6-substituted-2-benzothiazolamines and 3-substituted-2-imino-benzothiazolines.

Two series of analogues of riluzole, a blocker of excitatory amino acid mediated neurotransmission, have been synthesized: monosubstituted 2-benzothiazolamines and 3-substituted derivatives. Of all the compounds prepared in the first series, only 2-benzothiazolamines bearing alkyl, polyfluoroalkyl, or polyfluoroalkoxy substituents in the 6-position showed potent anticonvulsant activity against administration of glutamic acid in rats. The most active compounds displaying in vivo "antiglutamate" activity were the 6-OCF(3) (riluzole), 6-OCF(2)CF(3), 6-CF(3), and 6-CF(2)CF(3) substituted derivatives with ED(50) values between 2.5 and 3.2 mg/kg i.p. Among the second series of variously substituted benzothiazolines, compounds as active as riluzole or up to 3 times more potent were identified in two series: benzothiazolines bearing a beta-dialkylaminoethyl moiety and compounds with an alkylthioalkyl chain and their corresponding sulfoxides and sulfones. The most potent derivatives were 2-imino-3-(2-methylthio)- and 2-imino-3-(2-methylsulfinyl)-ethyl-6-trifluoromethoxybenzothiazolines (61 and 64, ED(50) = 1.0 and 1.1 mg/kg i.p., respectively). In addition, intraperitoneal administration of some of the best benzothiazolines protected mice from mortality produced by hypobaric hypoxia.

Animals↗
PubMed1999

Effects of aspiration versus neurotoxic lesions of the amygdala on emotional responses in monkeys.

All previous reports describing alterations in emotional reactivity after amygdala damage in monkeys were based on aspiration or radiofrequency lesions which likely disrupted fibres of passage coursing to and from adjacent ventral and medial temporal cortical areas. To determine whether this associated indirect damage was responsible for some or all of the changes described earlier, we compared the changes induced by aspiration of the amygdala with those induced by fibre-sparing neurotoxic lesions. Four different stimuli, two with and two without a social component, were used to evaluate the expression of defence, aggression, submission and approach responses. In unoperated controls, defence and approach behaviours were elicited by all four stimuli, 'social' and inanimate alike, whereas aggression and submission responses occurred only in the presence of the two 'social' stimuli. Furthermore, all defence reactions were reduced with an attractive inanimate item, while freezing was selectively increased with an aversive one. Relative to controls, monkeys with neurotoxic amygdala lesions showed the same array of behavioural changes as those with aspiration lesions, i.e. reduced fear and aggression, increased submission, and excessive manual and oral exploration. Even partial neurotoxic lesions involving less than two-thirds of the amygdala significantly altered fear and manual exploration. These findings convincingly demonstrate that the amygdala is crucial for the normal regulation of emotions in monkeys. Nevertheless, because some of the symptoms observed after neurotoxic lesions were less marked than those seen after aspiration lesions, the emotional disorders described earlier after amygdalectomy in monkeys were likely exacerbated by the attendant fibre damage.

Affective Symptoms↗
PubMed1999

[Breast imaging].

Explore the source record for details and available documents.

Biopsy, Needle↗
PubMed1998

Stereotactic fine-needle aspiration cytology of nonpalpable breast lesions: Institut Curie's experience of 243 histologically correlated cases.

BACKGROUND: The early diagnosis of nonpalpable breast lesions is a medical challenge because of the low specificity of different radiologic modalities. Fine-needle aspiration cytology (FNAC) assisted by a stereotactic guidance is an adjunctive diagnostic approach in the management of these lesions. The primary purpose of this article was to assess the diagnostic accuracy of FNAC in patients with nonpalpable breast lesions. METHODS: Three hundred and seventy-one lesions from 357 patients (all female) underwent FNAC using the stereotactically guided technique. Of these cases, 243 lesions from 238 patients subsequently were acquired by surgical excisional biopsies and formed the basis of this study. Statistical analyses of the cytologic and the histologic diagnoses of these cases were performed. RESULTS: Histologically, 107 lesions (44%) were benign and 136 lesions (56%) were malignant. Of the 136 malignant lesions, cytology was concordant in 73 lesions (53.7%), suspicious in 15 lesions (11.0%), false-negative in 12 lesions (8.8%) (benign), and unsatisfactory in 36 lesions (26.5%). Among the 107 benign lesions, cytology was concordant with histology in 75 lesions (70.1%), whereas 4 lesions (3.7%) and 28 lesions (26.2%) were cytologically suspicious and unsatisfactory, respectively. No false-positive cytologies were found in the current series. CONCLUSIONS: The current prospective study indicates that mammography combined with FNAC provides an accurate and practical diagnostic approach for the majority of nonpalpable lesions. Patients with unsatisfactory and false-negative lesions should undergo excisional biopsy.

Adult↗
PubMed1998

Ultrasound-guided fine-needle aspiration cytology of nonpalpable breast lesions: Institut Curie's experience with 198 histologically correlated cases.

BACKGROUND: The value of ultrasound-guided fine-needle aspiration cytology (FNAC) in the diagnosis of nonpalpable breast lesions remains a subject of debate. To determine the accuracy of this procedure in these lesions, a comparative analysis with open surgical biopsy in 188 patients was performed. METHODS: Six hundred and fifty-four nonpalpable breast lesions detected by ultrasound in 585 patients were subjected to FNAC. Of these, 198 lesions (30.3%) from 188 patients were surgically excised. RESULTS: Histologically, 105 lesions (53%) were malignant and 93 (47%) were benign. Among carcinomas, 65 cases (61.9%) were concordant, whereas 21 cases (20%) were suspicious, 12 cases (11.4%) were false-negative (benign), and 7 cases (6.7%) were unsatisfactory for diagnosis. Among benign lesions, 80 cases (86%) were concordant, whereas 5 cases (5.4%) were suspicious, and 8 cases (8.6%) were unsatisfactory. No false-positive diagnoses were made. The sensitivity of the FNAC method was 87.8%, the specificity was 94.5%, and the positive predictive value was 94.6%. CONCLUSIONS: These results indicate that, with the exception of random microcalcified lesions, ultrasound-guided FNAC is a valuable and reliable technique in the diagnosis of nonpalpable breast lesions.

Adult↗