Telomerase activation in a model of lung adenocarcinoma.

Ovine pulmonary adenocarcinoma (OPA) is a lung cancer strikingly similar to the pneumonic-type mixed invasive adenocarcinoma with a predominant bronchioloalveolar component in humans. Telomerase activity in OPA and the potential involvement of the kinase Akt in telomerase activation and regulation of cell proliferation were investigated. Lung tissues were collected from sheep with a histopathological diagnosis of OPA or controls. Epithelial cell cultures were derived in vitro from lung tissues. Telomerase activity was evaluated using the telomeric repeat amplification protocol method. Phosphorylation of Akt was detected by Western blotting. Telomerase activity was significantly higher in OPA lung tissues compared to control lung tissues. A high telomerase activity was detected in eight out of 12 (67%) primary cell cultures derived from tumours. A high level of expression of phosphorylated Akt was found in 10 out of 27 (37%) tumours, with abolition of Akt activation in response to epidermal growth factor stimulation demonstrated in primary cell cultures derived from tumours. Telomerase activation takes place in ovine pulmonary adenocarcinoma tumour cells and may be partly attributable to Akt activation. Telomerase may inhibit cellular senescence and contribute to the accumulation of tumour cells in mixed adenocarcinoma with a bronchioloalveolar component. Further work is necessary to identify alternative signalling pathways of telomerase activation in tumours.

[JSRV (jaagsiekte sheep retrovirus) and ovine pulmonary carcinoma]. / JSRV (jaagsiekte sheep retrovirus) et cancer du poumon associé chez le mouton.

JSRV (jaagsiekte sheep retrovirus) is a betaretrovirus, infecting small ruminants. This virus is responsible for the development of pulmonary adenocarcinoma, by the transformation of epithelial cells of the bronchioli and alveoli. This animal cancer is related to human bronchioloalveolar cancer (BAC), a specific form of human lung cancer for which a viral etiology has been proposed for several decades. In small ruminants JSRV interacts with the cells through the Hyal2 receptor. JSRV genome is simple and does not contain already known oncogene. It is now well established that the envelope protein is oncogenic by itself, via the cytoplasmic domain of the transmembrane glycoprotein and some domains of the surface glycoprotein. Activation of the PI3K/Akt and MAPK pathways participates to the envelope-induced transformation. The tumour development is associated with telomerase activation.

Perceptual correlates of neural plasticity related to spontaneous otoacoustic emissions?

The inner ear contains receptor cells that oscillate spontaneously, generating waves that propagate backward in the cochlea, ultimately causing sound to be radiated into the ear canal--the spontaneous otoacoustic emissions (SOAEs). Except in rare conditions, these internally generated signals appear to go unheard. The intensity of SOAEs admittedly hovers near the threshold of detection, but they are essentially continuous and perhaps last a lifetime. The hypothesis is tested that the frequency difference limen (DL(F)) is affected by SOAEs. The results show that the DL(F) systematically improves near SOAE frequencies, determined ipsi- or contralaterally to the SOAEs, arguing for a central effect. The results are discussed in the context of central plasticity.

An auditory negative after-image as a human model of tinnitus.

The Zwicker tone (ZT) is an auditory after-image, i.e. a tonal sensation that occurs following the presentation of notched noise. In the present study, the hypothesis that neural lateral inhibition is involved in the generation of this auditory illusion was investigated in humans through differences in perceptual detection thresholds measured following broadband noise, notched noise, and low-pass noise stimulation. The detection thresholds were measured using probe tones at several frequencies, within as well as outside the suppressed frequency range of the notched noise, and below as well as above the corner frequency of the low-pass noise. Thresholds measured after broadband noise using a sequence of four 130-ms probe tones (with a 130-ms inter-burst interval) proved to be significantly smaller that those measured using the same probe tones after notched noise at frequencies falling within the notch, but larger for frequencies on the outer edges of the noise. Thresholds measured following low-pass noise using the same sequence of probe tones were found to be smaller at frequencies slightly above the corner, but larger at lower, neighboring frequencies. This pattern of results is consistent with the hypothesis that the changes in auditory sensitivity induced by stimuli containing sharp spectral contrasts reflect lateral inhibition processes in the auditory system. The potential implications of these findings for the understanding of the mechanisms underlying the generation of auditory illusions like the ZT or tinnitus are discussed.

Validation assessment of a French version of the tinnitus reaction questionnaire: a comparison between data from English and French versions.

The present study compares the results obtained on original and French versions of the TRQ (Tinnitus Reaction Questionnaire) initially published by Wilson, Henry, Bowen, and Haralambous (1991) in English to evaluate the psychological distress of tinnitus sufferers. Reliability and validity of the French translation were determined using data from 173 normal hearing or hearing-impaired patients with tinnitus lasting from 1 month to 41 years. They completed the translated questionnaire and a short version of the Minnesota Multiphasic Personality Inventory. The results indicated good internal consistency (Cronbach's alpha = .94), and the reliability of the French version of the TRQ was demonstrated, except for items 5 and 20. High statistically significant correlations were found between the TRQ and Depression, Psychaesthenia, and Anxiety Mini-Mult subscales. The validation demonstrates only minor effects of language. The French version of the TRQ thus is an equally valid tool as the original English version for evaluating tinnitus distress of a patient.

Towards an objectification by classification of tinnitus.

OBJECTIVE: The objectives of this study are to identify the presence of tinnitus and classify its different forms, in terms of changes in noise. METHODS: Late auditory evoked responses (LAERs) were recorded from Fz in response to 1000 Hz tone bursts of various intensities, in 13 tinnitus-free subjects and in 25 tinnitus sufferers (16 bilateral and 9 unilateral tinnitus sufferers). A classification of different forms of tinnitus, in terms of changes in noise, was also undertaken. N1-P2 component amplitudes and N1 and P2 latencies were measured. RESULTS: Objective identification of the affected ear in unilateral tinnitus sufferers was found feasible on the basis of N1-P2 intensity-dependence and N1-P2 amplitude. The bilateral tinnitus group was found to differ from controls by greater intensity-dependence of the N1-P2 component and shorter N1 latency. These characteristics varied with tinnitus type: a classification on the basis of intensity-dependence and latencies proved feasible. The group of patients showing improved tinnitus in noise had greater intensity-dependence and longer N1 latency than did the group showing aggravated tinnitus in noise. CONCLUSIONS: Data are discussed in light of the inhibitory role of frontal cortex on the sensory inputs and the modulatory function of central serotonergic system on the processing of auditory information.

A selective imaging of tinnitus.

We selectively imaged the neural correlates of tinnitus, by contrasting a condition with no phantom auditory sensation with a condition during which tinnitus is present, using a rare form of tinnitus elicited by eye movements. Using positron emission tomography (PET), we demonstrate that phantom auditory sensation increases regional cerebral blood flow bilaterally in temporo-parietal association auditory areas but not in the primary auditory cortex. These results confirm that conscious perception does not necessarily require activation in primary areas and suggest that the perceptual qualities of tinnitus, e.g. intensity, frequency and spatial localization, are represented in temporo-parietal regions. Activation in these regions is compatible with cortical processing of ascending auditory messages generated at subcortical levels.

Psychopathological profile of tinnitus sufferers: evidence concerning the relationship between tinnitus features and impact on life.

This study involving 281 French tinnitus sufferers sought to investigate possible correlations between psychopathological profile and scores obtained from three tinnitus questionnaires. The patients all completed a French version of the Mini-Mult--a shortened Minnesota Multiphasic Personality Inventory--and French translations of three questionnaires designed especially for the clinical assessment of tinnitus: Tinnitus Reaction Questionnaire (TRQ), Subjective Tinnitus Severity Scale (STSS) and Tinnitus Handicap Questionnaire (THQ). Significant correlations were found (p < 0.0001) between scores on various Mini-Mult scales and total or factor 1 THQ and total TRQ scores. No significant correlation was found between the STSS and any Mini-Mult score.

Suppression of otoacoustic emission is unchanged after several minutes of contralateral acoustic stimulation.

The influence of variable durations of contralateral acoustic stimulation on the suppression of click-evoked otoacoustic emissions was investigated in order to determine whether olivocochlear efferent fibers are equally effective whatever the acoustical stimulation duration or if they show fatigue. The suppression effect was measured for contralateral stimulus durations ranging from 10 to 180 s prior to the onset of otoacoustic emission recording, and continuing throughout the recording time (60 s). No significant stimulus duration effect was found.

[Translation and validation of the questionnaire "Tinnitus Handicap Questionnaire, 1990]. / Traduction et validation du questionnaire "Mesure du handicap lié à l'acouphène" (Tinnitus Handicap Questionnaire, 1990).

OBJECTIVE: The Tinnitus Handicap Questionnaire (THQ) measures subjective tinnitus handicap in terms of emotional, social, and health impact (factor 1), hearing (factor 2), and perception of tinnitus (factor 3). A French version of the THQ was used with 178 tinnitus sufferers in ENT consultation. Internal validity was confirmed by correlations between (i) semigroups of items (Cronbach's alpha), (ii) item and total scores, and (iii) individual items, for each factor (Pearson's r), and was found to be strong (alpha = .90). All items (except 25 and 26) showed strong total-score correlations (.30 < or = r < or = .74). All factor 1 items intercorrelated strongly (.34 < or = r < or = .70). The factor 2 axis was coherent, with interitem correlations between .46 and .74, and its concurrent validation in strong factor 2 items correlations with hearing loss, if any (multiple linear regression: r = .67, p < .0001). Moreover, hearing-impaired (mean = 44.47 +/- 31.13) and normal-hearing (mean = 15.2 +/- 21.10) factor 2 scores were significantly different. CONCLUSION: As with the original THQ, factor 3 items were not strongly intercorrelated; moreover, items 25 and 26 failed to correlate with total score, suggesting that factor 3 is to be regarded with great caution.

Auditory efferents involved in speech-in-noise intelligibility.

Following studies proposing that medial olivocochlear efferents might be involved in the processing of complex signals in noise, we tested the involvement of efferent feedback in speech-in-noise intelligibility. Two approaches were used: measures of speech-in-noise intelligibility in vestibular neurotomized patients with cut efferents and comparison with normal hearing subjects; and correlations between effectiveness of olivocochlear feedback, assessed by contralateral suppression of otoacoustic emissions and speech-in-noise intelligibility in normal subjects. Contralateral noise improved speech-in-noise intelligibility in normal ears. This improvement, which was almost absent in de-efferented ears of vestibular neurotomized patients, was correlated with the strength of the olivocochlear feedback. Together, these results suggest that olivocochlear efferents play an antimasking role in speech perception in noisy environments.

2f1-f2 distortion product otoacoustic emission latency: changes with frequency and level of primaries.

Distortion product otoacoustic emissions (DPOAEs) provide a non-invasive and relatively direct method for evaluating cochlear travel time in humans. In the present study, the 2f1-f2 DPOAE latency was deduced from DPOAE phase shift according to f2 frequency shift, with f1 being fixed, using the ILO92 system. Latencies of 2f1-f2 DPOAEs were recorded at various primary frequencies and levels. Results were not wholly consistent with previous latency estimates. This study showed that the functions describing both 2f1-f2 DPOAE latency decrease with primary frequency increase, at several primary-tone levels, and 2f1-f2 DPOAE latency decrease with primary-level increase, at various frequencies, are best fit by exponential equations. The results of the evaluation of the latency-frequency-level relationship indicated the possibility of linking these three variables by the following expression: Latency = 68.30 exp (-0.027I -0.000434 f)+1.13.

Influence of contralateral noise on distortion product latency in humans: is the medial olivocochlear efferent system involved?

To test the hypothesis of temporal modifications of cochlear responses when medial efferents are activated, otoacoustic emission latencies were estimated in 16 normal human subjects, in the presence and absence of a contralateral broadband noise, using measurements of the phase of the 2f1-f2 distortion product (group latency method). Significant decrease in the latency of lower frequency (0.8-2.7 kHz) emissions was found in the presence of increasing levels of contralateral sound, and this effect disappeared when the primary-tone levels increased to 60 dB SPL. To ensure that effects were not attributable to mechanisms involving middle ear structures, susceptible to activation by contralateral sound, latency measures were performed in seven subjects whose efferents were severed during a vestibular neurotomy and in two subjects with paralyzed stapedial muscle. Results in patients were compared to those obtained in three surgical control patients with intact efferent bundle, and in eight other normal subjects. All the subject groups exhibited a decrease in latency under contralateral sound except the patients with the severed efferent system who showed increased latencies.

[Validation of French translation of the "Tinnitus Reaction Questionnaire", Wilson et al. 1991]. / Validation d'une traduction française du questionnaire "mesure de la détresse liée à l'acouphène (Tinnitus Reaction Questionnaire, Wilson et al. 1991).

The present study proposes a validation of a french translation of the TRQ initially published by Wilson et al., for evaluating the psychological distress of tinnitus sufferers. The 26 items translated into french were used on a sample of 173 tinnitus sufferers, who also filled out the Mini-Mult, a short version of the MMPI proposed by Kincannon. Internal validity was demonstrated by strong correlations (i) between each item (except items 5 and 20) and total TRQ score (0.33 < or = r < or = 0.87, p < or = 0.0001), (ii) between each internal TRQ factor (0.58 < r < 0.81, p < 0.0001) and the others. Cronbach's alpha test also showed the questionnaire to have a good internal validity (alpha = 0.94). The external factors used for testing concurrent validity were the scores on depression, psychaesthenia and anxiety Mini-Mult scales. The strong correlations (one factor ANOVA and simple linear regression tests) between scores on depression and psychaesthenia scales and (1) each TRQ item, (2) each TRQ factor, (3) total TRQ scores, confirmed concurrent validity. Scores obtained on anxiety index showed high correlations only with TRQ score, factor 3 score and some TRQ items (most of them included in factor 3). The internal and concurrent validities of the French version of the TRQ justify the use of this questionnaire, with the reserve that items 5 and 20 appeared irrelevant for the measuring of tinnitus distress in French-speaking countries. Such a questionnaire should improve our knowledge of tinnitus' life-impact and enable detection of patients whose psychological distress necessitates rapid intervention.

Phase delay measurements of distortion product otoacoustic emissions at 2f1-f2 and 2f2-f1 in human ears.

The present study used distortion product otoacoustic emission (DPOAE) latency as a tool to provide information about the generation sites of 2f1-f2 and 2f2-f1 DPOAEs in humans. The DPOAE 2f1-f2 is supposed to be generated near the f2 site, but little is known about the 2f2-f1 DPOAE processing in humans. The present work sought to test several hypotheses as to the possible generation of 2f1-f2 at the f2 site and of 2f2-f1 at the 2f2-f1 site as well as their backward reflection site, by comparing latencies of the two DPOAEs, under appropriate frequency manipulation. The effect of stimulus level was also studied. The latency values were calculated as the phase-lag related to the frequency shift, using the ILO92 software. Amplitudes were lower and latencies shorter for 2f2-f1 than for 2f1-f2. As expected, 2f1-f2 and 2f2-f1 DPOAE latency decreased with increasing stimulus level and frequency. At 70 dB SPL, latencies of DPOAEs with primaries f1 and f2 or f*1 and f*2, chosen so as to obtain 2f*1-f*2 = 2f2 - f1, were identical, whereas at 55 dB SPL the similarities were less obvious, suggesting two different generation processes. The present study suggests that the comparison of several DPOAE components may produce useful information about their processing within the cochlea.

Antinociceptive effects of oral clonidine and S12813-4 in acute colon inflammation in rats.

Acute colonic inflammation was induced by perendoscopic injection of 50 microleters of dilute formalin (5%) in the depth of the colonic wall (c.w.) in rats. Compared to saline injection, the procedure was followed by nociceptive behaviors from which visceral nociception was quantified. The alpha 2-adrenoceptor agonist, clonidine 2-[2,6-dichlorophenylamine]-2-imidazole hydrochloride (75, 150 and 300 mg/kg), administered orally 15 min after c.w. injection of formalin significantly reduced the nociceptive responses at the high dose only. However, when administered 30 min prior to nociceptive stimulation, the compound exhibited an antinociceptive effect at the three doses. A novel analgesic, the compound "S12813-4' 3-[2-(4-phenylpiperazine-1-yl)-ethyl]-2-oxo-2,3-dihydro-oxazolo[b] pyridine, chlorydrate (10, 30 and 90 mg/kg), given orally displayed antinociceptive effects whatever the administration schedule, before or after c.w. injection of formalin. The antinociceptive effect of S12813-4 (30 mg/kg given orally) was prevented by subcutaneous (s.c.) injection of yohimbine or idazoxan (1 mg/kg). We conclude that visceral nociception elicited by formalin-induced colonic inflammation is attenuated by clonidine and S12813-4. The pharmacological profiles of the two compounds and the inhibition of the antinociceptive effect of S12813-4 by yohimbine and idazoxan suggest that noradrenergic mechanisms are involved in the transmission and/or modulation of the nociceptive influx arising from the inflamed colon.

Contralateral acoustic stimulation induces a phase advance in evoked otoacoustic emissions in humans.

In 28 normal-hearing human subjects, the medial olivocochlear efferent system was activated by contralateral acoustic stimulation which is able to mimic the inhibitory effects of electrical stimulation of the crossed olivocochlear bundle. A first experiment on 16 subjects demonstrated that a contralateral white noise of 35 dB SL was able to induce temporal changes on transiently evoked otoacoustic emissions in response to clicks of 63 dB SPL. These temporal changes consisted of an advance of click-evoked otoacoustic signals in 87% of cases and is referred to as phase-shift effect. The phase advance, quantified using two signal processing methods in both time and frequency domains, was found to be mainly associated with lower frequencies, with a maximal effect at 1.5 kHz and minimal effects around 3.5 and 4 kHz. In a second experiment, carried out on 12 subjects, a negative relationship was found to exist between the ipsilateral stimulation level (level of clicks ranging from 57 to 69 dB SPL) and the phase-shift effect (PSE). Specifically in the range of levels tested (25-45 dB SL), a linear relationship presenting no obvious saturation effect was observed between the contralateral level and the PSE. The PSE was examined in 6 additional subjects exhibiting pathological symptoms; 2 of 3 individuals, who had no contralateral stapedial reflexes unilaterally, showed the PSE whereas this response was reduced or absent in 3 other subjects in the ear with severed efferents associated with a vestibular neurotomy. The integrity of olivocochlear efferents was, therefore, necessary to obtain a full effect, but the absence of stapedial reflex did not prevent the effect from occurring.

Is perilymphatic pressure altered in tinnitus?

Tinnitus is characterized by the continuous or intermittent auditory perception of various sounds (buzzing, whistling, etc.) in the absence of any external stimulus. Perilymphatic hyperpressure is one of the numerous mechanisms which could hypothetically be involved in tinnitus generation. In the present experiment, perilymphatic pressure was measured indirectly using the tympanic membrane displacement technique. Twenty-five tinnitus patients were investigated at 10, 15 and 20 dB above the acoustic reflex threshold with ipsilateral stimulation. The variables Vi (inward tympanic displacement), Vm (mean tympanic displacement) and their variations according to stimulus level were compared between tinnitus sufferers and age-matched or hearing-matched controls. Tympanic displacement was measured in sitting and supine positions so as to evaluate cochlear aqueduct patency. No systemic changes in response occurred in tinnitus patients, except at a high stimulation level, perhaps due to hearing impairment.