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Biomedical subjects

R Couderc

Publications and source records attributed to R Couderc.

At least 19 recordsLinked to original sources
PubMed2005

Results of cochlear implantation in two children with mutations in the OTOF gene.

OBJECTIVE: The purpose of the study is to present the results of cochlear implantation in case of deafness involving mutations in the OTOF gene. This form of deafness is characterized by the presence of transient evoked otoacoustic emissions (TEOAE). In cases of profound deafness with preserved TEOAE, two main etiologies should be considered: either an auditory neuropathy (a retrocochlear lesion) or an endocochlear lesion. It is essential to differentiate these two entities with regards to therapy and screening. PATIENTS: We report two children who presented with profound prelingual deafness, confirmed by the absence of detectable responses to auditory evoked potentials (AEP), associated with the presence of bilateral TEOAE. Genetic testing revealed mutations in OTOF, confirming DFNB9 deafness. Both patients have been successfully implanted (with a follow-up of 18 and 36 months, respectively). MAIN OUTCOME MEASURES: Clinical (oral production, closed and open-set words and sentences list, meaningful auditory integration scale), audiometric evaluation (TEOAE, AEP) before and after implantation, and neural response telemetry (NRT). RESULTS: Both patients present a good quality of clinical responses and electrophysiological tests after implantation, indicating satisfactory functioning of the auditory nerve. This confirms the endocochlear origin of DFNB9 and suggests that these mutations in OTOF lead to functional alteration of inner hair cells. CONCLUSION: In the absence of a context of neurological syndrome, the combination of absent AEP and positive TEOAE should lead to a genetic screening for mutations in OTOF, in order to undertake the appropriate management.

Audiometry↗
PubMed2004

Screening of SLC26A4 (PDS) gene in Pendred's syndrome: a large spectrum of mutations in France and phenotypic heterogeneity.

Sensorineural hearing defect and goiter are common features of Pendred's syndrome. The clinical diagnosis of Pendred's syndrome remains difficult because of the lack of sensitivity and specificity of the thyroid signs. The identification of PDS as the causative gene allowed molecular screening and enabled a re-evaluation of the syndrome to identify potential diagnostic characteristics. This report presents the clinical and genotypic findings of 30 French families, for whom a diagnosis of Pendred's syndrome had been made. Twenty-seven families had at least one mutated allele. Twenty-eight different mutations were identified, 11 of which had never been previously reported. The main clinical characteristics were: early hearing loss, fluctuation in terms of during deafness evolution, and the presence of an enlarged vestibular aqueduct.

Adolescent↗
PubMed2002

FOXC2 truncating mutation in distichiasis, lymphedema, and cleft palate.

We report a family showing autosomal-dominant segregation of upper- and lower-eyelid distichiasis (double row of eyelashes) in seven affected relatives over three generations, in addition to below-knee lymphedema of pubertal onset (lymphoedema proecox) in three. Two children had cleft palate in addition to distichiasis, but without the previously reported association with the Pierre-Robin sequence. Other ophthalmologic anomalies included divergent strabismus and early-onset myopia. This family was found to be completely linked to markers mapped to 16q24.3 and thereby proposed to be allelic to the distichiasis-lymphedema syndrome (DL, MIM 153400), although pterygium colli, congenital heart disease, or facial dysmorphism were not features found here. As FOXC2/FKLH14 mutations were found to underlie DL and diverse hereditary lymphedema conditions, this gene was examined by sequence analysis. An out-of-frame deletion (914-921del) was identified and found to segregate with the disease, further highlighting the phenotypic heterogeneity of lymphedema conditions linked to FOXC2 truncating mutations. Whether such heterogeneity is related to genotype-phenotype correlation, a hypothesis not primarily supported by the apparent loss-of-function mechanism of the mutations, or governed by modifying genes, remains to be determined.

Abnormalities, Multiple↗
PubMed2001

Possible relationship between the van der Woude syndrome (vWS) locus and nonsyndromic cleft lip with or without cleft palate (NSCL/P).

Cleft lip with or without cleft palate (CL/P) is one of the most common congenital malformations in humans occurring with a birth prevalence of approximately 1:1,000. CL/P may be part of a defined syndrome, sequence or association, although most individual or familial cases present as an isolated (nonsyndromic) malformation (NSCL/P). Inheritance is generally regarded as multigenic although, in some families, NSCL/P seemingly segregates as a monogenic trait. On the other hand, van der Woude syndrome (vWS) is a rare autosomal dominant with cardinal features of lower-lip pits (LLP) and CL/P or cleft palate (alone). Since none of these traits is present in all mutation carriers, some individual or familial vWS cases, especially those lacking LLP, are indiscernible from NSCL/P, raising the question whether allelic variation at the vWS locus could underlie NSCL/P. This question was addressed using parametric linkage (LOD score) analysis in 21 multiplex NSCL/P families based on a tightly linked microsatellite marker (D1S3753), and nonparametric analysis using the transmission/disequilibrium test (GTDT) in 106 NSCL/P triads and selecting markers D1S205, D1S491, and D1S3753. No evidence for linkage of NSCL/P to vWS was found on the 21 families using the LOD score approach. In contrast, TDT yielded a significant P value of 0.04 for D1S205, supporting involvement of vWS in NSCL/P in a complex, modifying/polygenic manner rather than as a monogenic/major disease locus.

Alleles↗
PubMed2001

Pierre Robin sequence and interstitial deletion 2q32.3-q33.2.

Pierre Robin sequence (PRS) consists of the nonrandom association of micrognathia, cleft palate (CP), and glossoptosis. It also includes respiratory and feeding difficulties that appear to be neurogenic rather than mechanical in causation. Genetic determinants are thought to underlie this functional and morphological entity, based on the existence of Mendelian syndromes with PRS, and the rare observations of familial nonsyndromic PRS, in which some of the affected individuals have isolated CP. We report the association of PRS with deletion 2q32.3-q33.2 due to an unbalanced reciprocal translocation 46,XX, t(2;21), del 2(q32.3q33.2), and we refine the deletion interval with regard to YAC probes and polymorphic DNA markers. The deletion was shown to be flanked by D2S369 (telomeric) and D2S315 (centromeric), thus it maps to a recently determined chromosomal region known to be nonrandomly associated with CP. This observation supports the hypothesis for the genetic bases of nonsyndromic PRS, strengthens its possible genetic association with isolated CP, and provides a candidate PRS locus, in chromosomal region 2q32.3-q33.2.

Chromosome Banding↗
PubMed2001

Association of the apolipoprotein E epsilon4 allele with late-onset depression.

Apolipoprotein E (ApoE) phenotyping was determined in 42 subjects with Alzheimer's disease (AD), 49 with depression, including 26 with early-onset depression (EOD) and 23 with late-onset depression (LOD), and 49 controls. In the EOD group, the frequency of the ApoE epsilon4 allele was not different from the control frequency (p = 0.532) but was significantly lower than in AD (p < 0.001). In the LOD group, the ApoE epsilon4 frequency was significantly higher than in the controls (p = 0.034) but was not different from that in the AD group (p = 0.229). Individuals with ApoE epsilon4 were at greater risk of getting AD (odds ratio, OR = 5.5, 95% confidence interval, CI, 2.0-14.0) or LOD (OR = 6.1, 95% CI, 1.9-19.0) than of EOD (OR = 0.7, 95% CI, 0.2-2.5). These results suggest an association between the ApoE epsilon4 allele frequency and LOD. Patients with LOD could be at risk of developing AD by an epsilon4-dependent pathway.

Age of Onset↗
PubMed2001

Oxidative stress in hemodialyzed patients during exhausting exercise.

BACKGROUND: This study was designed to study the effect of an exhausting exercise test on plasma lipid peroxidation marker (malondialdehyde, MDA) and on vitamin E levels in hemodialyzed patients (HD) compared to healthy control subjects (HC). METHODS: Eight sedentary chronically HD, (39.0+/-10.8 years) and eight sedentary HC (38.4+/-12.4 years) were studied. Before exercise, the activity of scavenger enzymes [plasma and erythrocyte glutathione peroxidase (GPX), and erythrocyte superoxide dismutase (SOD)] was determined. All subjects performed a symptom-limited exercise test; respiratory gas exchanges were collected on-line and blood was sampled five min before exercise, at exhaustion and after 30 min of recovery. RESULTS: At rest, the activity of plasma and erythrocyte GPX and erythrocyte SOD was significantly lower in HD than in HC. Exercise provoked an increase of plasma MDA concentration after recovery in HD patients, whereas our HC group show a decrease in MDA plasma level immediately after exercise, returning to the rest values during recovery. Exercise induced no change of vitamin E concentration in HD whereas in HC it increased during recovery. CONCLUSIONS: Our results indicate that: 1) at rest: although hemodialyzed patients showed lower scavenger enzymes activity than HC subjects, there was no difference in MDA plasma level between groups; 2) there is some evidence that physical exercise contribute to oxidative stress during recovery in HD patients, and 3) exercise induced an increase in plasma vitamin E concentration in healthy subjects.

Adult↗
PubMed2000

[Constitutional deficiency of pulmonary surfactant protein B: clinical presentation, histologic and molecular diagnosis].

We report a female full-term infant with fatal respiratory failure of early onset due to inherited SP-B deficiency. Lung biopsy was performed at 18 days after birth, with histopathological characterization indicating congenital alveolar proteinosis. Immunohistochemical studies of lung tissue revealed the absence of SP-B and the presence of intra-alveolar SP-A normal quantities. Analysis of genomic DNA showed homozygosity for the 121ins2 mutation of the SFTPB gene. The infant died 21 days after birth. Both parents were heterozygotes for the mutation. Chorionic villus sampling was performed at the first trimester of the following pregnancy. Restriction analysis of amplified fetal DNA, studies of microsatellite segregation and direct sequencing led to the diagnosis of homozygosity for the parental wild-type allele. The diagnosis of congenital SP-B deficiency should be suspected whenever an early and acute respiratory failure in a term or near-term infant does not resolve after five days of age: diagnostic confirmation can be easily and rapidly obtained with the analysis of genomic DNA and immunohistochemical characterization of lung tissue.

DNA Mutational Analysis↗
PubMed2000

The apolipoprotein E epsilon4 allele and the response to tacrine therapy in Alzheimer's disease.

The objective of our study was to evaluate the effects of the apolipoprotein E (ApoE) phenotype and gender on the response to tacrine treatment in Alzheimer's disease (AD). ApoE phenotyping was performed on 76 patients treated with tacrine for AD. This group comprised 33 ApoE epsilon4 allele carriers (epsilon4+) and 43 non-epsilon4 carriers (epsilon4-). Patients were treated blindly in relation to the ApoE phenotype, with incremental tacrine dosages ranging from 40 mg/day up to the highest dosage (160 mg) tolerated without side-effects. At least 6 weeks elapsed between each increase. Changes in the scores for the Alzheimer Disease Assessment Scale-Cognitive Component (ADAS-Cog) between baseline and each increment in dosage were assessed in the epsilon4- and epsilon4+ groups. The cut-off point for being considered as responsive to tacrine treatment was a 4-point decrease in the ADAS-Cog score. There was no tendency for the epsilon4- carriers to respond better than the epsilon4+ carriers. When patients were stratified by gender, no differences were found between the effects of the treatment on men and women. Consequently, these results do not support the hypothesis that the ApoE phenotype and gender are predictors of the response to tacrine in AD patients.

Aged↗
PubMed2000

Interferon beta1a therapy changes lipoprotein metabolism in patients with multiple sclerosis.

To assess whether interferon beta1a (IFNbeta1a) therapy affects plasma lipoprotein metabolism, twelve patients with relapsing-remitting multiple sclerosis (MS) were studied during a two-year follow-up period. High density lipoprotein (HDL2) cholesterol and the HDL2/HDL3 ratio were increased at year 2 and lipoprotein (a) was transitorily increased at year 1, in comparison to baseline levels. Apolipoprotein A-I was lower and apolipoprotein E higher at year 1, only in a subgroup of patients who experienced relapses and/or progressed during therapy. These findings suggest that IFNbeta1a treatment is associated with changes in the lipoprotein metabolism. Alterations in this metabolism could be related to the immunomodulatory actions of the drug and the disease activity in multiple sclerosis patients.

Adult↗
PubMed2000

Comparison of a new method for the direct and simultaneous assessment of LDL- and HDL-cholesterol with ultracentrifugation and established methods.

BACKGROUND: Automated electrophoresis combined with enzymatic cholesterol staining might improve routine assessment of LDL- and HDL-cholesterol (LDLC and HDLC), as an alternative to the Friedewald equation and precipitation. A new method (Hydrasys; SEBIA) that adapts the cholesterol esterase/cholesterol oxidase reaction within urea-free gels was evaluated. METHODS: Fresh sera from 725 subjects (512 dyslipidemics) were analyzed by electrophoresis, in parallel with sequential ultracentrifugation, beta-quantification, calculation, and precipitation. RESULTS: Electrophoresis was linear up to 4 g/L cholesterol, with a detection limit of 0.042 g/L cholesterol/band. Within-run, between-run, between-batch, and between-operator imprecision (CVs) were 1.6%, 2.0%, 1.5%, and 2.7% for LDLC, and 3.9%, 4.3%, 5.5%, and 4.9% for HDLC, and remained unchanged up to 6.3 g/L plasma triglycerides (TGs). Precision decreased with very low HDLC (<0.25 g/L). Serum storage for 3-7 days at +4 or -80 degrees C did not interfere significantly with the assay. Agreement with beta-quantification was stable for LDLC up to 5.07 g/L (r = 0.94), even at TG concentrations >4 g/L (r = 0.91). Bias (2.88% +/- 12%) and total error (7.84%) were unchanged at TG concentrations up to 18.5 g/L. Electrophoresis predicted National Cholesterol Education Program cut-points with <0.04 g/L error, exactly and appropriately classified 79% and 96% of the subjects, and divided by 2.4 (all subjects) and 5.8 (TGs >1.5 g/L) the percentage of subjects underestimated by calculation. One-half of the patients with TGs >4 g/L had LDLC >1.30 g/L. For HDLC, correlation was better with precipitation (r = 0.87) than ultracentrifugation (r = 0.76). Error (-0.10% +/- 26%) increased when HDLC decreased (<0.35 g/L). Direct assessment of the LDLC/HDLC ratio detected 45% more high-risk subjects than the calculation/precipitation combination. CONCLUSIONS: Electrophoresis provides reliable quantification of LDLC, improving precision, accuracy, and concordance over calculation, particularly with increasing plasma TGs. Implementation of methods to detect low cholesterol concentrations could extend the applications for HDLC assessment.

Adolescent↗
PubMed2000

Sites internet

http://biotribune.com/ Biotribune.com ou la biologie medicale sur internet. Ce site est concu comme un portail sur la biologie clinique. Accueil d'internautes sur une page comportant, entre autres, les rubriques : actualite, evenements, revue des connaissances, rubrique juridique et petites annonces. Biotribune propose regulierement des dossiers rediges par des specialistes comportant une mise a jour des connaissances orientee sur l'interet diagnostique des tests de biologie clinique. Le site propose egalement une revue de presse scientifique avec des resumes courts d'articles parus dans les grands journaux internationaux tels que The Lancet, New England Journal of Medicine, Science, etc. Vous pouvez aussi y tester vos connaissances grace a des cas cliniques et des QCM. Ce site propose egalement des petites annonces pratiques pour les laboratoires de ville (remplacement, materiel d'occasion, etc.). Les problemes touchant l'assurance qualite, les RMO et la nomenclature font egalement l'objet d'information et de commentaires. Enfin, vous pourrez vous inscrire a l'un des forums proposes : discussion biomedicale ou opinion et reaction sur les sujets touchant au professionnel de la biologie medicale. En conclusion, un site complet et agreable que l'on souhaite voir s'enrichir et se renouveler regulierement. http://www.arcol.asso.fr Site du Comite francais de coordination de recherche sur l'atherosclerose et le cholesterol (Arcol). Ce site s'adresse a la fois aux cliniciens, aux biologistes et aux non-specialistes interesses par la pathologie cardio-vasculaire et ses traitements. On y trouve des rubriques tres didactiques sur la physiopathologie et les facteurs de risque de l'atherosclerose, la prise en charge nutritionnelle et medicamenteuse des patients. On peut tester ses connaissances a l'aide des nombreux cas cliniques richement commentes. Ce site regulierement mis a jour contient egalement les recommandations nationales et internationales sur la prise en charge du patient hyperlipidemique. On y trouve, bien sur, toutes les rubriques telles que : agenda des congres, lien avec les autres sites web, bibliographie, etc. Un index par mots cles permet une recherche efficace. Un site indispensable a consulter pour tous ceux qui s'interessent aux lipoproteines et a l'atherosclerose. n R. Couderc

Journal Article↗
PubMed2000

Lp(a) is increased in hemodialysis patients according to the type of dialysis membrane: a 2-year follow-up study.

AIMS: Patients with chronic renal failure treated by hemodialysis develop lipoprotein abnormalities that may contribute to their increased risk ofatherosclerosis. This study shows lipid parameter follow-up procedure according to the type of dialysis membrane in an unselected population of 33 hemodialysis patients. PATIENTS AND METHODS: The study included 33 patients with end-stage renal disease and 110 healthy blood bank donors of Tenon Hospital. Cholesterol and triglycerides were determined by enzymatic methods, apoA-I, apoB by immunoturbidimetry and Lp(a) by immunonephelemetry. Apo(a) phenotyping was performed by agarose gel electrophoresis followed by immunoblotting. Patients and controls subjects were estimated by Student's t- and chi2-tests. RESULTS: Patients dialyzed with low-flux membranes had Lp(a) concentrations higher than patients dialyzed with high-flux membranes. Patients dialyzed with polyacrylonitrile membranes (AN 69) had an apoA-I concentration significantly lower than patients dialyzed with hemophane or polysulfone membranes. We also confirmed some of the lipid abnormalities and high Lp(a) concentrations in ESRD patients. CONCLUSION: These results may contribute to a more rational choice of the dialysis membrane in hemodialysis patients.

Adult↗
PubMed2000

Use of a reference material proposed by the International Federation of Clinical Chemistry and Laboratory Medicine to evaluate analytical methods for the determination of plasma lipoprotein(a).

BACKGROUND: As part of the NIH/National Heart, Lung and Blood Institute Contract for the Standardization of Lipoprotein(a) [Lp(a)] Measurements, a study was performed in collaboration with the IFCC Working Group for the Standardization of Lp(a) Assays. The aims of the study, performed with the participation of 16 manufacturers and 6 research laboratories, were to evaluate the IFCC proposed reference material (PRM) for its ability to transfer an accuracy-based value to the immunoassay calibrators and to assess concordance in results among different methods. METHODS: Two different purified Lp(a) preparations with protein mass concentrations determined by amino acid analysis were used to calibrate the reference method. A Lp(a) value of 107 nmol/L was assigned to PRM. After uniformity of calibration was demonstrated in the 22 evaluated systems, Lp(a) was measured on 30 fresh-frozen sera covering a wide range of Lp(a) values and apolipoprotein(a) [apo(a)] sizes. RESULTS: The among-laboratory CVs for these samples (6-31%) were, in general, higher than those obtained for PRM (2.8%) and the quality-control samples (14%, 12%, and 9%, respectively), reflecting the broad range of apo(a) sizes in the 30 samples and the sensitivity of most methods to apo(a) size heterogeneity. Thus, although all of the assays were uniformly calibrated through the use of PRM, no uniformity in results was achieved for the isoform-sensitive methods. CONCLUSIONS: Linear regression analyses indicated that to various degrees, apo(a) size heterogeneity affects the outcome of the immunochemical methods used to measure Lp(a). We have also shown that the inaccuracy of Lp(a) values determined by methods sensitive to apo(a) size significantly affects the assessment of individual risk status for coronary artery disease.

Calibration↗
PubMed1999

Apolipoprotein E phenotypes in demented and cognitively impaired patients with and without cerebrovascular disease.

Controversy exists regarding the apolipoprotein E (ApoE) epsilon4 allele association with vascular dementia (VaD), ranging from increased epsilon4 frequency, similar to that found for Alzheimer's disease (AD), to no association between the epsilon4 allele and VaD. To clarify further the relationship between ApoE alleles polymorphism and cerebrovascular disease (CVD) in demented and cognitively impaired patients, we examined the ApoE phenotypes in a sample of 280 patients: 155 with AD, 21 with VaD, 32 with mixed dementia (MD), 45 with mild cognitive impairment (MCI) but without CVD, and 27 in which vascular disease was the most probable cause of cognitive decline [vascular mild cognitive impairment (VMCI)]. Our results show that the frequency of the ApoE epsilon4 allele in patients over 70 years old with clinically diagnosed VaD and VMCI does not differ significantly from that of controls. In contrast, ApoE epsilon4 allele-bearing individuals had greater risk of having late-onset AD (OR = 8.8; 95% CI 3.7-21.0), or non-vascular cognitive impairment (OR = 7.0; 95% CI 2.5-19.0).

Aged↗