Electrovestibulogram: first results in the guinea pig.

This paper describes a method of investigation of the peripheral vestibular system. Electrical stimulations (ES) are applied on the round window of chronically implanted guinea pigs, with and without vestibular stimulation (either per or post rotational accelerations). The whole nerve action potential recorded at the output of the internal auditory meatus, the difference between the two conditions, reveals the change in electrical excitability and thus presumably in discharge rate of vestibular fibres determined by rotational stimuli.

Liver transplantation, including the concept of reduced-size liver transplants in children.

Since the establishment of a clinical program in liver transplantation in 1984, 162 liver transplants have been performed in 131 patients (78 adults, 53 children). The patient mortality rate while waiting for a suitable organ has been 8% for adults and only 4% for children (25-46% reported in the literature). The low pediatric mortality is a result of the use of reduced-size liver transplants.

Relationship between the nephrotoxicity and ototoxicity induced by gentamicin in the guinea pig.

Guinea pigs were treated with daily single subcutaneous injections of 60 mg gentamicin per kg for 3 weeks. Renal, cochlear and vestibular functions were monitored before, during and after treatment. The degree and onset of gentamicin oto- and nephrotoxocity differed during the treatment period.

Inflammation due to surgical glove powders in the rabbit eye.

Inflammatory anterior chamber reactions secondary to contamination by talc, absorbable dusting powder (ADP), and a combination of these powders were studied in rabbits. These common surgical glove powders were introduced into the anterior chambers of 30 animals, and structural changes were observed on days 1 and 3, and at weeks 1, 4, 8, and 12. Our findings indicate that the combination of talc and ADP causes a substantially more acute inflammatory reaction than either agent used individually.

Limits of ABR and contribution of transtympanic electrocochleography in the assessment of cerebellopontine angle tumours.

Auditory brainstem responses (ABR) and transtympanic electrocochleography (ECochG) were analysed for 63 patients with tumours of the cerebellopontine angle (CPA) and/or internal auditory meatus (IAM). ABR recordings indicated a clearly prolonged wave I-V interval (above 4.3 ms) in half of the patients, hence suggesting a retrocochlear disorder.

Gastritis cystica polyposa.

Gastritis cystica polyposa was diagnosed in five patients between ages 29 and 61 years. All five had been operated on for peptic ulcer disease three to 26 years earlier, when gastroenteric anastomoses had been made. The presenting complaint was abdominal pain, nausea and vomiting, or gastrointestinal bleeding.

Potassium-depolarization induces motility in isolated outer hair cells by an osmotic mechanism.

Outer hair cells in vitro contract in response to various stimuli: electrical stimulation, K+-depolarization, elevation of intracellular calcium or osmotic changes of the extracellular medium. The characteristics of motile responses induced by K+-depolarization, osmotic changes, and calcium injection were compared in this study in order to delineate the underlying mechanisms. Slow shape changes in outer hair cells were induced by changes of the osmolality or the K+/Na+-ratio of the bathing medium, or by intracellular injections of calcium.

Neuroanatomical study of Galen's anastomosis (nervus laryngeus) in the dog.

To further knowledge of the laryngeal nerves, the nerve fibers of Galen's anastomosis were studied using two neuroanatomical methods, namely nerve degeneration and horseradish peroxidase labeling. It is demonstrated that the superior laryngeal nerve forms part of the tracheal and esophageal nervous system. The value of the results in relation to physiological laryngeal studies and to human laryngeal diseases is discussed.

Clinical significance of the summating potential in Menière's disease.

Transtympanic (TT) electrocochleography (ECochG) data recorded with click stimuli and tone bursts (1, 2, 4, and 8 kHz) were evaluated in 50 patients with Meniere's disease and compared with the data from control groups of 10 sensorineural hearing impaired patients and 5 subjects with normal hearing. The mean summating potential (SP) amplitude was larger in the Meniere's disease group for 1, 2, and 8 kHz. The low frequency (1 or 2 kHz) SP decreased in 59% of the Meniere's disease patients during a glycerol dehydration test, whereas subjective hearing improved in only 29%.

Frequency selectivity: reliability of electrocochleographic measures with iso-intensity masking.

In a group of 12 normal or hearing-impaired subjects, frequency selectivity was determined psychoacoustically and electrophysiologically with the fast ECochG iso-intensity masking procedure, using a 4 kHz test tone and simultaneous pure-tone masking. Psychoacoustic curves measured twice for each subject were reproducible and showed a broadening related to hearing loss. The curves determined with ECochG repeated two or three times for each subject varied greatly for half of the subjects and their widths were not related to hearing loss.

Effects of electrolytic lesions of the superior olivary complex and trapezoid body on brainstem auditory-evoked potentials in the guinea pig. II. Three-channel Lissajous' trajectory analysis.

Brainstem auditory-evoked potentials (BAEP) were studied both with vertex (positive) - tragus (negative) derivation and three-channel Lissajous' trajectory (3-CLT) planar analysis in guinea pigs (GP) after destruction of the ipsilateral superior olivary complex (SOC) (6 GP), contralateral SOC (8 GP) referred to the stimulation side, and trapezoid body (TB) in the sagittal line (8 GP). The size of the lesion was evaluated on histological examination. The right ear was locally destroyed with aminoside instillation.

Effects of electrolytic lesions of the superior olivary complex and trapezoid body on brainstem auditory-evoked potentials in the guinea pig. I. Vertex-tragus recordings.

Brainstem auditory-evoked potentials (BAEP) were recorded between vertex and tragus in 22 guinea pigs, after destruction of the contralateral ear in order to produce monaural stimulation. Stimuli employed were 100 dB SPL clicks and tone bursts. Normative recordings showed five positive peaks, P1-P5 and four negative peaks, N1-N4.

The impact of long-term therapy by a multidisciplinary team on the education, occupation and marital status of growth hormone deficient patients after termination of therapy.

Forty-two GH deficient patients (14 isolated GH deficiency (IGHD), 28 multiple pituitary hormone deficiencies (MPHD), 23 males and 19 females) were evaluated after termination of hGH therapy and achievement of final height. IGHD patients were found to score higher in intelligence quotients (IQ) than the MPHD patients. The educational and occupational achievements of all patients positively correlated with their IQ level.

Glycine immunoreactivity in the brainstem auditory and vestibular nuclei of the guinea pig.

An immunohistochemical study was performed on the brainstem of the guinea pig, using a specific antibody against glycine. Glycine-like immunoreactivity was observed in stellate and multipolar neurons in the cochlear nucleus, in the medial and lateral nuclei of the trapezoid body and in the ventromedial periolivary cell group. No immunoreactive neurons were found in the vestibular nuclei.

[Responses evoked in "steady state" in man by means of a sinusoidal frequency modulation].

The response of the human auditory system to a 40 Hz sinusoidal modulation of the frequency of a tone can be reliably recorded from the human scalp using Fourier analysis. With increasing intensity the amplitude of the response becomes larger and its phase delay shorter. The response amplitude is larger and the phase delay longer for lower carrier frequencies.

Distribution of VIII nerve excitation by pure tones, derived by electrical stimulation and acoustic masking.

VIII nerve compound action potentials evoked by electrical stimulation are decomposed in series of pure-tone derived potentials using masking. These potentials are in turn decomposed in a series of contributions from various frequency bands by adding high-pass masking noises. The amplitudes of the derived signals are thought to be proportional to the number of fibres activated by the masking acoustical stimulations.

Stapedius reflex and cerebellopontine angle tumours.

The stapedius reflex was investigated in 61 patients with cerebellopontine angle tumours, in order to evaluate the reliability of the reflex-decay test in VIIIth nerve disorders. The reflex was completely normal in 11% of the patients. The 2 most frequently observed abnormalities were (1) an absence of the reflex when stimulating the ear on the side of the tumour, and (2) the conjunction of pathological reflex-decay at 0.

Ototoxicity of teicoplanin in the guinea pig.

Experiments were performed on guinea pigs to assess the eventual ototoxic side effects of a new glycopeptide antibiotic called teicoplanin. For a better validation, in the same study other animals were treated with tobramycin, a well known ototoxic antibiotic of the aminoglycoside family, and a group of control animals was also constituted. Antibiotic treated animals were injected with the high dose of 90 mg/kg/day during 21 consecutive days.

Osmotically induced motility of outer hair cells: implications for Menière's disease.

Osmolarity changes in inner ear fluids have long been considered to be contributing factors to Menière's disease. Our present study demonstrates that small changes in the osmolarity of a surrounding in vitro medium induce fast contractions (hypo-osmotic solution) or elongations (hyperosmotic solution) in isolated outer hair cells of the guinea pig. These changes were reversible upon returning cells to iso-osmotic conditions.

Mathematical analysis of VIIIth nerve cap with a linearly-fitted experimental unit response.

The compound action potential (CAP) recorded at the round window has for some time been investigated in order to determine the underlying temporal spike sequence: the firing probability density (FPD) function of the fibres. Charlet de Sauvage et al. [(1980) Hear.

3,5-Diamino-1,2,6-thiadiazine 1,1-dioxide derivatives: synthesis and antiparasitic activity.

The synthesis of new 3,5-diamino-1,2,6-thiadiazine 1,1-dioxide derivatives is described and their structures discussed on the basis of 1H and 13C-N.M.R.