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Biomedical subjects

B Fraysse

Publications and source records attributed to B Fraysse.

At least 19 recordsLinked to original sources
PubMed2006

Importance of metallothioneins in the cadmium detoxification process in Daphnia magna.

Good knowledge of the relationship between toxic metals and biological systems, particularly the sub-cellular fraction, could be a suitable early indicator of toxic effects. These effects and the sub-cellular behaviour of cadmium were studied with a widely used species in freshwater toxicity bioassays, Daphnia magna. In spite of this very commonplace usage in ecotoxicological studies, very few data are available on its toxicant metabolism and in particular metal homeostasis. Combining multi-tools analysis, a soluble protein was found: it is heat-stable, rich in sulfhydryl groups (differential pulse polarography), characterised by a molecular mass of approximately 6.5 kDa, with a G-75 chromatographic profile corresponding to the rabbit metallothioneins monomer, with few if any aromatic-containing amino acids, it binds metals (e.g. Cd, Cu), and its concentration increases with Cd exposure. This evidence led us to hypothesise that metallothioneins (MTs) are present in D. magna. Up to 75% of the Cd body burden with Cd exposure is bound to the MTs fraction. The increase in the Cd concentration in the surrounding medium and concomitantly in daphnids induces sub-cellular reorganisation of essential metals such as Cu and Zn. The rate of metals in the soluble cellular fraction and associated with MTs increases with the Cd body burden. Monitoring sub-cellular distribution of metals after exposure in the natural environment could be very useful for ecotoxicological assessment.

Animals↗
PubMed2005

Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system.

One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement procedure. Recordings were obtained in 96% of these subjects with this standardised procedure. The group results are presented in terms of peak amplitude and latency, slope of the amplitude growth function and ECAP threshold. The effects of aetiological factors and the duration of deafness on the ECAP were also studied. While large intersubject variability and intrasubject variability (across electrodes) were found, results fell within a consistent pattern and a normative range of peak amplitudes and latencies was established. The aetiological factors had little effect on the ECAP characteristics. However, age affected ECAP amplitude and slope of the amplitude growth function significantly; i.e., the amplitude is higher in the lowest age category (15-30 years). Principal component analysis of the ECAP thresholds shows that the thresholds across 5 electrodes can be described by two factors accounting for 92% of the total variance. The two factors represent the overall level of the threshold profiles ('shift') and their slopes across the electrode array ('tilt'). Correlation between these two factors and the same factors describing the T- and C-levels appeared to be moderate, in the range of 0.5-0.6.

Action Potentials↗
PubMed2005

[Vestibular dysfunction after cochlear implantation: a national multicenter clinical study].

Vertigo and dizziness are the most common complications of cochlear implantation. Data of a multicentric study about clinical aspects and cost utility were collected for vertigo and dizziness: incidence, clinical and treatment were analyzed among 469 adults and children. Results demonstrated that 16% of adults and 3% of children experienced dizziness postoperatively. In a few cases a specific mechanism as perilymphatic fistula was identified. In other cases the mechanism underlying delayed vertigo remains speculative and endolymphatic hydrops was suggested.

Adolescent↗
PubMed2004

A longitudinal study on postoperative hearing thresholds with the Vibrant Soundbridge device.

The Vibrant Soundbridge is a semi-implantable middle ear hearing device used in the rehabilitation of adults with sensorineural hearing loss. In order to evaluate the long-term effects of the implanted part of the device, audiological data from 39 patients implanted over several implant sites across France were collected and analyzed retrospectively. The mean follow-up time was 16 months; 25 patients had a follow-up period of over 1 year. Surgery was uneventful in all cases. The present study of the 39 implanted patients with a mid- to long-term follow-up found a statistically significant modification of hearing thresholds (pre- versus postoperative) for frequencies of 0.5 and 4 kHz. However, the shift of threshold was rather limited (2.79 and 3.34 dB, respectively), and this variation was not statistically different from the evolution of the opposite non-operated ear.

Adult↗
PubMed2004

Effects of advanced oxidation processes (AOPs) on the toxicity of a mixture of pharmaceuticals.

The possibility of applying main AOP techniques, namely ozonation, H2O2/UV photolysis and TiO2 photocatalysis to provide a significant reduction of toxicity of pharmaceutical mixtures has been evaluated. For the preparation of the mixture six pharmaceuticals were chosen among those found at highest concentrations in Sewage Treatment Plant effluents, namely carbamazepine, clofibric acid, diclofenac, sulfamethoxazole, ofloxacin and propranolol. The blue-green alga Synechococcus leopoliensis and the rotifer Brachyonus calyciflorus were utilised to assess the toxicity of the mixtures after AOP treatments. All the toxicity tests were performed using chronic standardized bioassays. The best results were obtained with ozonation. With this type of treatment a complete removal of mixture toxicity on S. leopolensis was obtained even after the shortest time of application (1 min). The ozonation treatment leads also to removal of all the pharmaceutical mixture toxicity on B. calyciflorus, by applying the oxidizing agent for at least for 2 minutes.

Animals↗
PubMed2002

Effects of Cd and Zn waterborne exposure on the uptake and depuration of 57Co, 110mAg and 134Cs by the Asiatic clam (Corbicula fluminea) and the zebra mussel (Dreissena polymorpha)--whole organism study.

Groups of zebra mussels (Dreissena polymorpha) and asiatic clams (Corbicula fluminea) were exposed to cadmium and zinc with the aim of studying the effect of these metals on the 57Co, 110Ag and 134Cs uptake and depuration by these freshwater bivalves. In the presence of zinc, the 57Co concentration factor for the whole organism of the two species was halved, notably because of a decrease of the uptake parameter. Conversely, Zinc and the Cd + Zn mixture increased the 110mAg uptake process by clams and mussels. The two metals also increased the depuration of this radionuclide in mussels, whereas this phenomenon was only observed in clams exposed to cadmium. In comparison with 57Co and 110mAg, the 134Cs bioconcentration was 5-10 times lower in D. polymorpha and not detected in C. fluminea. This weak contamination by this radionuclide resulted from a lower uptake and a higher depuration parameters.

Animals↗
PubMed2002

[Use of auditory brain stem implant in a patient with bilateral vestibular schwannoma (type 2 neurofibromatosis].

Surgical technique and functional results of implantation of the acoustic implant of the brain stem (BS) are described for a 16-year-old patient with bilateral vestibular shvannoma (neurofibromatosis of type 2). Initially, a large (IV degree) tumor was removed from the left cerebellopontile angle using the translabyrinthine-transcochlear approach. The function of the facial nerve recovered completely. The BS implant was implanted a year later in the course of removing shvannoma from the right cerebellopontile angle using the above approach. The patient received 22-channel implant Nucleus-CI22M. Speech intelligibility improved by 90-100%. BS implantation is today the only effective method of reestablishment of acoustic sensations in patients with bilateral destruction of the acoustic nerves due to bilateral vestibular shvannoma.

Adolescent↗
PubMed2001

Multicenter audiometric results with the Vibrant Soundbridge, a semi-implantable hearing device for sensorineural hearing impairment.

The Vibrant Soundbridge, a semi-implantable hearing device for subjects with moderate to severe sensorineural hearing impairment was introduced commercially. First audiologic results are presented on 63 patients from 10 European implant centers. Hearing loss was at 0.5, 1, 2, and 4 kHz varying between 43 and 81 dB HL. The patients used the analogue audio processor, type 302. Measured sound-field gain was compared with NAL-R target values. For most patients an acceptable agreement was found. There was a subgroup of patients, however, with relatively low gain. The results suggest that this was related to the suboptimal positioning and fixation of the transducer to the incus.

Audiometry, Speech↗
PubMed2001

Sensorineural hearing loss and otosclerosis: a clinical and radiologic survey of 437 cases.

The aim of this study was to determine if a relationship exists between bone level thresholds and the extension of otosclerotic foci within the otic capsule. The study consisted of a retrospective case review in a university hospital. We included patients who underwent surgery for otosclerosis in our department and who had a CT scan prior to surgery. We analyzed the data charts and CT scans of 437 cases (386 patients). On CT scan, we distinguished patients with fenestral otosclerosis and/or with a pericochlear focus. A pericochlear focus could be extended (Group 2) or not (Group 1) to the cochlear endosteum. Data for Groups 1 and 2 were compared with those for the control group of all patients for whom CT scan showed no cochlear focus (Group 3). Of the 437 CT scans, 399 were positive (91.3%). An anterior focus was reported in 305 cases (69.8%), a footplate thickening in 21 cases (4.8%) and both anomalies were encountered in 60 cases (13.7%). A pericochlear focus was reported in 53 examinations. This focus was extended to the endosteum in 14 cases (26.4% of the pericochlear foci). In Group 1, preoperative air conduction (AC) thresholds were significantly lower than in the control group (p < 0.05). The air--bone gap was also significantly larger in Group 1 (p < 0.05). Bone conduction (BC) thresholds were lower in Group 1 than in the control group but the difference was not significant. In Group 2, preoperative AC thresholds were significantly lower than in the control group (p < 0.05). BC thresholds were also lower in Group 2 than in the control group and the difference was significant (p < 0.05). As a result of this study, we assume that there may be a relationship between bone level thresholds and the radiological extension of otosclerosis within the otic capsule.

Adult↗
PubMed2001

Vestibular schwannomas: correlations between magnetic resonance imaging and histopathologic appearance.

BACKGROUND: The indication for surgery of vestibular schwannomas (VS) remains controversial and depends on several factors. The ability to predict their patterns of growth would allow better surgical planning. This growth may depend on tumoral proliferation but also depends on dystrophic changes. OBJECTIVE: The aim of this study was to evaluate the role of magnetic resonance imaging (MRI) in predicting the evolution of VS. For this purpose, the authors attempted (1) to compare the MRI appearance of VS with its histopathologic features, (2) to correlate the MRI appearance of VS and its histopathologic features with its size, and (3) to evaluate the index of proliferation (IP) of each VS. PATIENTS AND METHODS: Thirty VS were studied with MRI before surgery. The VS were measured and classified as homogeneous, heterogeneous, and cystic. After surgery, IP was evaluated with immunohistochemical study using MIB-1 monoclonal antibody, and compared with tumor size. Pathologic studies evaluated the prevalence of Antoni type A and type B tissue, the amount of fibrosis, and the presence of siderin-loaded macrophages, xanthomatous cells, and cysts. RESULTS: The IP was low (0.2%-2.2%) and was not correlated with VS size. On MRI, 13 VS were homogeneous, 12 heterogeneous, and 5 cystic. The 13 homogeneous VS were smaller and were predominantly made of Antoni type A tissue. The 12 heterogeneous and 5 cystic VS were larger and were predominantly made of Antoni type B/mixed tissue. Heterogeneous and cystic VS showed significantly more hemosiderin deposits. There was a significant relation between the amount of hemosiderin deposits and the mean size of VS. Microscopic cysts were observed only in VS with cystic MRI appearance. Fibrosis was present in all tumors regardless of their size and MRI appearance. CONCLUSION: A heterogeneous MRI aspect (correlated with larger mean size) not only is related to the ratio of type A to type B tissue but also is caused by other pathologic changes, mainly hemosiderin deposits and cystic formation. Increasing tumor size probably depends less on IP than on dystrophic changes (hemosiderin, cysts) and/or on the presence of type B tissue.

Adolescent↗
PubMed2001

Correlations between computed tomography findings and family history in otosclerotic patients.

BACKGROUND: Otosclerosis is a heritable disease affecting the otic capsule. Its genetics have been studied since the 19th century, but several issues remain controversial. OBJECTIVE: The goals of this study were to assess the prevalence of sporadic and familial forms of otosclerosis in a population of otosclerotic patients and to compare the radiologic findings between both groups. STUDY DESIGN AND SETTING: This retrospective study was conducted in a single institution. PATIENTS: This study included 211 patients operated on for otosclerosis. MAIN OUTCOME MEASURES: Clinical data, including pure tone audiograms, were available from patients' charts. A questionnaire assessing family history of otosclerosis and deafness was mailed to the otosclerotic patients. A relative was considered otosclerotic if surgery confirmed the disease. The family history was correlated with the computed tomography results. This examination was performed before surgery in all patients. RESULTS: A family history of otosclerosis was found in 24.2% of the patients. The radiologic findings differed between patients with a sporadic form of otosclerosis and those with a familial form. The lesions were more often detectable, bilateral, and severe in the familial forms (p < 0.05). CONCLUSION: These findings lead to the assumption that fenestral radiologic otosclerosis occurs more in sporadic forms, whereas more extensive lesions on computed tomography seem to indicate the familial forms. Hereditary forms demonstrated to be familial seem to lead to more severe disease. The search for a genome locus of otosclerosis may be enlightened by these findings.

Adult↗
PubMed2001

A multicenter study of the Vibrant Soundbridge middle ear implant: early clinical results and experience.

OBJECTIVE: The Vibrant Soundbridge (VBS; Symphonix Devices, Inc., San Jose, CA, U.S.A.) is an active, semi-implantable, middle ear hearing device that directly drives the ossicular chain and is used in the treatment of patients with mild to severe sensorineural hearing loss. The benefits of the VBS and the effects of surgery were examined and compared with the preoperative aided condition in 25 patients with implants. STUDY DESIGN: Single-subject repeated-measures evaluations were performed with each patient acting as his or her own control. Objective audiologic measures and subjective questionnaires also were used. SETTING: Five tertiary referral and teaching hospitals. SUBJECTS: Adult patients had bilateral sensorineural hearing loss (average hearing loss, 56 dB; range, 33-80 dB). Twenty-one patients had worn a conventional hearing aid before surgery (11 binaurally, 10 monaurally). Four patients had not used a conventional hearing aid before surgery. INTERVENTION: Rehabilitative. RESULTS: No significant change in residual hearing after surgery was observed. Functional gain was significantly superior with the VBS. No significant differences were observed for aided speech recognition in quiet. A significant improvement in communication in various listening conditions was reported with the VBS as compared with conventional hearing aids. CONCLUSION: The VBS surgical implantation procedure does not affect the residual hearing level in the implanted ear, nor does it present any unacceptable risk. Measurable benefit from the VBS in comparison with conventional amplification was demonstrated with regard to the provision of superior usable amplification and greater ease in communication in daily listening environments for the majority of patients.

Acoustic Stimulation↗
PubMed2001

Clinical experience with the Vibrant Soundbridge implant device.

OBJECTIVE: To evaluate the full degree and range of benefits provided by the Vibrant Soundbridge (VSB; Symphonix Devices, Inc., San Jose, CA, U.S.A.) and analyze pre-and postoperative results of audiologic tests. STUDY DESIGN: Single-subject study with each subject serving as his or her own control. SETTING: Multicenter clinical study conducted at 10 centers in Europe. PATIENTS: 47 patients who met the selection criteria for participation in the study. INTERVENTIONS: Implantation of the VSB direct-drive middle ear hearing device. MAIN OUTCOME MEASURES: Average change in unaided thresholds with the patient wearing headphones at each frequency pre-and postsurgery was measured. A mean threshold change less than 5 dB across all frequencies was considered clinically nonsignificant. RESULTS: 47 patients had successful surgery for implantation and fitting with the VSB device. CONCLUSION: The VSB is a new middle ear implant device that can be used safely in the treatment of patients with moderate to severe sensorineural hearing loss.

Acoustic Stimulation↗
PubMed2001

Expression of the Na(+)/Ca(2+) exchanger in skeletal muscle.

The expression of the Na(+)/Ca(2+) exchanger was studied in differentiating muscle fibers in rats. NCX1 and NCX3 isoform (Na(+)/Ca(2+) exchanger isoform) expression was found to be developmentally regulated. NCX1 mRNA and protein levels peaked shortly after birth. Conversely, NCX3 isoform expression was very low in muscles of newborn rats but increased dramatically during the first 2 wk of postnatal life. Immunocytochemical analysis showed that NCX1 was uniformly distributed along the sarcolemmal membrane of undifferentiated rat muscle fibers but formed clusters in T-tubular membranes and sarcolemma of adult muscle. NCX3 appeared to be more uniformly distributed along the sarcolemma and inside myoplasm. In the adult, NCX1 was predominantly expressed in oxidative (type 1 and 2A) fibers of both slow- and fast-twitch muscles, whereas NCX3 was highly expressed in fast glycolytic (2B) fibers. NCX2 was expressed in rat brain but not in skeletal muscle. Developmental changes in NCX1 and NCX3 as well as the distribution of these isoforms at the cellular level and in different fiber types suggest that they may have different physiological roles.

Age Factors↗