Effects of contralateral white noise on click-evoked emissions in normal and sensorineural ears: towards an exploration of the medial olivocochlear system.

The association between contralateral stimulation and evoked otoacoustic emissions (EOAEs) allows study of sound-evoked olivocochlear feedback and then of the medial olivocochlear system. A method allowing quantification of sound-evoked olivocochlear feedback is proposed. The feedback is present in almost all normal-hearing subjects, but with great interindividual variability. In sensorineural hearing loss, the feedback is present in 20 out of 21 subjects. One paradoxical clinical case is described with a unilateral increase of EOAE intensity during contralateral stimulation.     

Effect of contralateral acoustic stimulation on active cochlear micromechanical properties in human subjects: dependence on stimulus variables

1. Outer hair cells (OHCs) have active micromechanical properties that are thought to be the origin of evoked otoacoustic emissions (EOAEs). In the present study, click-evoked otoacoustic emissions were recorded in humans with or without various contralateral acoustic stimulations. A previous study, concentrating on contralateral stimulation with broadband noise, had shown a decrease of the EOAE amplitude in humans. Results support a role for the efferent system in cochlear mechanics; indeed, medial efferent neurons of the olivocochlear bundle terminate on the OHCs. To obtain a better understanding of the medial efferent system functioning in humans, the present study looked at the contralateral suppressive effect as a function of stimulus parameters. 2. The study of the input-output function of the EOAE amplitude with and without a 50-dB SPL contralateral broadband noise showed that the suppressive effect was equivalent to a mean reduction of 3.77 dB. 3. For the EOAEs to tone pips, the contralateral suppressive effect was strongest when the contralateral ear stimuli were narrow bands that were centered around the central EOAE frequency. This frequency specificity disappeared for contralateral narrow band noise levels greater than 50 dB SPL. 4. The contralateral suppressive effect was also observed with transient contralateral sounds (nonfiltered clicks). Significant reductions of the EOAE amplitude were seen with contralateral click levels as low as 17.5 dB SL. Above this level, the EOAE amplitude decreased as the contralateral stimulus level increased. This effect was still present in subjects without any stapedial reflex, but absent in total unilateral hearing-loss subjects. Therefore this suppressive effect is unlikely to be due to alteration of the middle ear function or to transcranially conducted sound. 5. When the contralateral interclick interval exceeded 14.2 ms. the suppressive effect was smaller. With contralateral stimulus level maintained subjectively constant, the effect was found to disappear when the interclick interval was greater than 49.9 ms. A saturation of the contralateral suppressive effect was observed for click rates greater than 70/s (interclick interval less than 14.2 ms). 6. Our study confirms and specifies the contralateral sound suppression effect on cochlear mechanisms in humans, assessing the equivalent reduction, showing a frequency specificity and extending these findings to contralateral transient sounds. Any influence of the acoustic crosstalk was eliminated. A role played by middle ear muscles cannot be absolutely ruled out but is not necessary to produce such a contralateral suppressive effect (the effect being found in subjects after surgical removal of the stapedius muscle) and could not explain the frequency specificity.(ABSTRACT TRUNCATED AT 400 WORDS)     

Approche psychosociologique des familles de toxicomanes consultant auprès de centres pour parents

Sans résuméCet article a été élaboré à partir du rapport de recherche remis à l'I.N.S.E.R.M. en 1986 dans le cadre d'un contrat de recherche externe. Le travail a été effectué, sous la direction du Dr C.Orsel, par le Service Analyses et Statistiques de l'Association L'Ab baye (D. Rösch, H. Collet, M. F. Chauveau), en collaboration abec les équipes cliniques de L'Orangerie et du Centre Monceau à Paris, animées par Mmes Reille-Soult et Angel-Sternschuss. La partie informatique et statistique a été traitée en collaboration avec Mr Pleuvret, informaticien, et Mr Lebart, Directeur de Recherche au C.N.R.S. et au C.R.E.D.O.C. Editorial note: This article is being published in French, as it was accepted before the decision was made that all articles will appear in English. It is an exception.     

A novel C202F mutation in the connexin26 gene (GJB2) associated with autosomal dominant isolated hearing loss

Mutations in the GJB2 gene encoding connexin26 (CX26) account for up to 50% of cases of autosomal recessive hearing loss. In contrast, only one GJB2 mutation has been reported to date in an autosomal dominant form of isolated prelingual hearing loss. We report here a novel heterozygous 605G→T mutation in GJB2 in all affected members of a large family with late childhood onset of autosomal dominant isolated hearing loss. The resulting C202F substitution, which lies in the fourth (M4) transmembrane domain of CX26, may impair connexin oligomerisation. Finally, our study suggests that GJB2 should be screened for heterozygous mutations in patients with autosomal dominant isolated hearing impairment, whatever the severity of the disease.


Keywords: C202F mutation; connexin26 gene (GJB2); autosomal dominant hearing loss     

In vitro influence of thymopentin on proliferative responses and phytohemagglutinin-induced interleukin 2 production in normal human lymphocyte cultures

Immunologic Research - Peripheral human blood lymphocytes from healthy blood donors were investigated in vitro to observe the influence of different doses of thymopentin on nonstimulated...     

Spermatocytic seminoma. A clinicopathological and immunohistochemical study of 7 cases

Spermatocytic seminoma is an uncommon tumor, representing less than 1% of the testicular tumors, occurring most often in old patients. We report 7 cases of this entity. The average age at presentation was 66 years. Tumors had a polymorphic appearance with small, intermediate and large cells, and "spireme" figures. They were pure, with no sarcomatous component. In all cases, the tumor was limited to the testis. In the peritumoral tissue, there was no intratubular germ cell proliferation, and no atrophic testis. Immunostaining was negative for all the classical antibodies tested (cytokeratins, PLAP, lymphoid markers), but all the cases expressed c-kit (100%). This membranous positivity was focal in 4 cases, very strong, and diffuse in the 3 others. Spermatocytic seminoma must be recognized, because its favorable evolution in absence of a sarcomatous component. Adequate treatment consists of orchidectomy alone. Positive staining for c-kit may be helpful for the diagnosis of spermatocytic seminoma.     

Evaluation of the prognosis of mitral valve prolapse

It is not easy to evaluate the prognosis of mitral valve prolapse. First of all, a positive diagnosis is difficult: the clinical insufficiencies are ill-compensated by sonocardiography as it is less reliable than expected; the very existence of the "mitral valve prolapse" described by Barlow is being challenged. Secondly, the most severe complications of mitral prolapse are rare, with respect to its frequency. Some complications are currently well defined. Thus, severe mitral insufficiency, leading to valve replacement, affects elderly men more than young women, although the pathological lesions correspond to the same disease. Endocarditis is rare and only occurs when there is an audible murmur. Rhythm disorders are varied, with however, frequent junction tachycardias and a marked influence of catecholamines, which may explain the clinical effectiveness of beta-blockers. Unfortunately, severe complications are not as well known. Thus, the risk of sudden death and cerebral vascular accident cannot be figured out from large statistical studies. Only studies of some so called "risk" sub-groups, should allow a better knowledge of these two complications and a more effective prevention.     

Orosensory Perception of Fat/Sweet Stimuli and Appetite-Regulating Peptides before and after Sleeve Gastrectomy or Gastric Bypass in Adult Women with Obesity

The aim of this study was to explore the impact of bariatric surgery on fat and sweet taste perceptions and to determine the possible correlations with gut appetite-regulating peptides and subjective food sensations. Women suffering from severe obesity (BMI > 35 kg/m²) were studied 2 weeks before and 6 months after a vertical sleeve gastrectomy (VSG, n = 32) or a Roux-en-Y gastric bypass (RYGB, n = 12). Linoleic acid (LA) and sucrose perception thresholds were determined using the three-alternative forced-choice procedure, gut hormones were assayed before and after a test meal and subjective changes in oral food sensations were self-reported using a standardized questionnaire. Despite a global positive effect of both surgeries on the reported gustatory sensations, a change in the taste sensitivity was only found after RYGB for LA. However, the fat and sweet taste perceptions were not homogenous between patients who underwent the same surgery procedure, suggesting the existence of two subgroups: patients with and without taste improvement. These gustatory changes were not correlated to the surgery-mediated modifications of the main gut appetite-regulating hormones. Collectively these data highlight the complexity of relationships between bariatric surgery and taste sensitivity and suggest that VSG and RYGB might impact the fatty taste perception differently.     

Effectiveness of a training program in reducing infections in toddlers attending day care centers

The objective of this study was to assess the effectiveness of a hygiene program in reducing the incidence of respiratory and diarrheal diseases in toddlers attending day care centers. A randomized field trial was conducted in 52 day care centers in Quebec, Canada, between September 1, 1996 and November 30, 1997. Absences for any reasons and the daily occurrence of colds and/or diarrhea in toddlers were recorded on calendars by the educators. The number of fecal coliforms on children's hands and on educators' hands was measured during three unannounced visits. Overall, 1,729 children were followed in 47 day care centers for a total of 153,643 child-days. The incidence rate of diarrhea was considerably reduced by the effect of monitoring (IRR = 0.73, 95% CI = 0.54,0.97), and the intervention reduced the incidence rate of upper respiratory tract infections (IRR = 0.80, 95% CI = 0.68,0.93). Monitoring alone also had an important effect in reducing the level of bacterial contamination on children's and educators' hands. The results indicate that both an intervention program and monitoring alone play a role in reducing infections in children attending day care centers.