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[Changes in nystagmus following otolith stimulation].

In rabbits, stimulation of the otolith organs was shown to exert a double effect on nystagmus evokedby adequate stimulation of semicircular canals' receptors: The immediate and the delayed. On simultaneous stimulation of the two portions of vestibular apparatus, inhibition of systagmus occurs. In the course of aftereffect of the otolith stimulation, both the activated and the inhibited responses as well as the responses similar to control can be revealed, depending on the time interval between presentationsof otolith and cupulous stimuli.

Animals↗

[Acute sensorineural hearing loss at the Otorhinolaryngology Department of the General Hospital in Subotica 1991-1996].

INTRODUCTION: Sudden sensorineural hearing loss is an acute hearing loss of a perceptive type, of unknown etiology, in most cases one-sided, or, a every sudden sensorineural deafness that occurs in the period of three days or less. Modern scientific literature points to three possible etiological factors: viral cochleitis, vascular lesion of the labyrinth and unrecognized rupture of the membranous labyrinth. The therapy for this disease is extremely various. There are dozens of reported different (or similar) healing protocols, including vasodilators, Hydroxyethyl starch, low molecular dextran, diuretics, defibrinogenation, fibrmolytic therapy, steroids, prostacyclin, oxygen therapy, hyperbaric oxygen therapy, vitamins, etc. The aim of the study was to recapitulate in brief modern views of etiology and therapy of the sudden sensorineural hearing loss, to analyze cases of this illness within the period of 1991-1996 in our Otorhinolaryngology Department and to compare these data with the same or similar data of other authors. MATERIAL AND METHODS: In this study, medical records of patients admitted in the period of 1991-1996 in the Otorhinolaryngology Department of the Health Center in Subotica with a diagnosis of sudden sensorineural hearing loss were used. There were 53 patients with this diagnosis. All patients were treated in the hospital with infusions of rheoactive drugs. During the diagnostic procedure, all patients underwent a complete clinical otorhinolaryngologic examination, detailed anamnesis was taken, acoustic impedance tests (tympanometry) and tonal liminal audiometry were performed. Routine blood test was made (including complete blood picture, sedimentation rate, blood sugar) and a complete urine examination. Sometimes we demanded x-ray of the temporal bones (Schnller and Stenwers). A short increment sensitivity index (SISI) test and Carhart test were also made, if necessary. Function of the vestibular system was tested in cases when the vestibular symptoms were more strongly expressed. This test was made after passing an acute attack of vertiginous symptoms. Control audiometry was made on the seventh and on the fourteenth day after admission. This therapy consisted of an infusion of physiologic solution (NaCl) 250 or 500 ml twice daily to which 300 mg xanthinol nicotinate ampulla, paracetam 1 g ampulla, dipyridamole 10 mg ampulla and C-vitamin 10% 500 mg ampulla were applied. The number of paracetam and xanthinol nicotinate ampullas was raised on the 14/day, and then it fell to the starting value. The therapy lasted 17 days. Patients were given multivitamine peroral therapy, tranquilizers and diet without coffee, smoking and allergenic food. RESULTS AND DISCUSSION: The study included 53 patients, 27 (50.94%) female and 26 (49.06%) males (Graph 1). Their age (Graph 2) ranged between 16-71 years. The biggest group of patients was between 40-49 (39.62%) years of age. Distribution per year (Graph 3) shows that the incidence of the acute sensorineural hearing loss differs from the findings of other authors, especially in the period of 1991-1994, due to very few cases. Connection of this illness with seasons is shown in Graph 4. We had most cases during summer time (August, 16.98%). There is a mild rise in winter (December, 13.21%). The degree of the hearing loss in decibels is shown in the Graph 5. Most of the patients (75.47%) had mild or severely damaged hearing (40-85 dB). Period of the deafness before patients were admitted to the hospital, is shown in Graph 7. Most of them came in the first seven days after they experienced acute deafness (52.83%). Symptomatology of the persons with acute hearing loss is shown in Table 1. All of them had the feeling of deafness, and 50.94% also had tinnitus. Table 2 shows that only two patients had a pathologic finding (hypo function) on the vestibular caloric test. 57.14% of patients tested by this method showed a normal function of the vestibular apparatus. The recovery of he

Adolescent↗

[Morphogenesis of Mauthner neurons of Xenopus laevis tadpoles following early unilateral eye enucleation].

The connection between Mauthner neuron (CMN) and visual analyzer in Xenopus laevis tadpoles was studied using these neurons capacity to change their morphogenesis during the development in case of interruption of their connections with afferent fibres. In phase 31 of development tadpoles were subjected to unilateral enucleation of eye. Morphogenesis of contralateral (experimental) and ipsilateral (control) MN with respect to the operated eye was followed up. Comparison with intact Mauthner neuron of the tadpole of the same age who were not exposed to operation was conducted. Contralateral MN were found to be delayed in development phases 47 and 50. This was associated with 1.5-3.3 fold difference in neuron body central section area and 2-3 fold differences in nuclear section area. Three-dimensional reconstruction revealed lower number of cell processes in contralateral MN as well as decline in their length and diameter. Control and intact MN showed no difference similar to experimental and control ones in phase 41. The data obtained indicate that MN of Xenopus laevis tadpole possess powerful ipsilateral connections originating from the side of visual analyzer and contralateral ones from the side of the eye. This affects MN development and in contrast to octavolateral system (including vestibular apparatus and organs of lateral line) controls the contralateral neuron.

Animals↗

Topographic analysis of inner ear lesions in profoundly deafened patients with tympanogenic and meningogenic labyrinthitis using three-dimensional magnetic resonance imaging.

OBJECTIVE: High-resolution magnetic resonance imaging (MRI) provided clear images of three-dimensional (3D) reconstruction of the inner ear in candidates for cochlear implantation. In this study. semiquantitative analysis of the 3D MRI findings was performed to investigate topographic lesions of the inner ear caused by tympanogenic and meningogenic labyrinthitis. STUDY DESIGN: This was an observational study. SETTING: The study was performed in an academic, comprehensive, multispecialty group practice. PATIENTS: Postlingual deafened patients with cochlear implantation. The cause of deafness was tympanogenic or meningogenic labyrinthitis. INTERVENTION: High-resolution 3D MRI and postoperative speech recognition tests were used. RESULTS: Abnormal findings in the inner ear detected with MRI were found before surgery in 58.3% of the patients with meningogenic labyrinthitis, although the incidence was lower in patients with tympanogenic labyrinthitis. Abnormal MRI findings were frequently observed in the cochlear basal turn and semicircular canals more than in the middle and apical turn in cases with meningogenic etiology. Patients with tympanogenic labyrinthitis suffered less with a vestibular apparatus than did those patients with meningogenic labyrinthitis. Regarding the analysis of the inner ear lesions at the implanted side, the postoperative speech recognition ability did not correlate to the extent of abnormal MRI findings of the implanted ear. CONCLUSION: Improvement in 3D MRI technology provided an accurate preoperative picture of the inner ear apparatus. In cochlear implant patients with infectious labyrinthitis, the extent of the inner ear lesion detected with 3D MRI was different among etiologies of deafness.

Adult↗

[Cellular responses to vibration during dental drilling with belt drive motor engine (in vitro) (author's transl)].

There have been many reports on the pulpal reaction caused by vibration during high speed dental drilling with air turbine hand-piece. It is, however, not clear pulpal responses to vibration of low speed drilling with 7 000 rpm of belt drive motor engine which produces a fundamental vibration of about 170 cps having most unpleasant sensation at vestibular apparatus. Here, cellular responses of L strain cells to vibration derived from 7 000 rpm and 15 000 rpm of belt drive motor engine were observed in vitro system. There is no difference between the both cellular responses to the vibration of 7 000 rpm and 15 000 rpm. Suspended free cells were easily influenced and degenerated by the vibration, and remarkably checked in their cell-multiplication. On the contrary, in the cells adhered to the substratum of glassware, no degeneration and no inhibitory effect were observed. And the cells showed reversible response of cytoplasmic shrinkage only.

Cell Adhesion↗

In the centenary of the birth of Anna Maria Di Giorgio (1897-1961).

Anna Maria Di Giorgio was born on December 22nd,1897 in San Daniele del Friuli. She graduated in Natural Sciences at the University of Florence in 1921. Her career was undertaken in the Institute of Human Physiology of that University under the guide of prof. Gilberto Rossi, one of the most illustrious italian Physiologists, who was her mentor. She was the first woman to win a competition for a Universitary Professorship of Physiology. She was appointed director of the Institutes of Physiology of the Universities of Siena (1938-42) and Turin (1942-61) where she died in 1961. In the centenary of her birth it seemed worthy to commemorate prof. Di Giorgio and her scientific work. She brought fundamental contributions in the field of Neurosciences, in particular on the cerebellum, vestibular apparatus and psychophysiology of vision. She was a pioneer in showing for the first time the plasticity in the spinal cord by the end of the twenties. In addition, she discovered a nystagmogenic center in the cerebral cortex. Her physiological findings have been widely confirmed and are now patrimony of the Neurosciences.

History, 20th Century↗

Psychophysiological aspects of increasing resistance to space motion sickness.

One of the actual and difficulty solved problems of the adaptation period to microgravitation is space motion sickness (MS) that has the negative influence on well-being and performance of crewmembers in the initial and highly crucial phase of the orbital flight. Among the prophylactic measures for decrease of the unfavourable influence of space MS the preflight training is of great importance, and its role in perspective undoubtedly will grow in connection with increase of the number of crewmembers. During the last years several authors received experimental materials evidenced that as a base of more effective increase of resistance to space MS there may be used adequate modelling of the main physiological effects of the adaptation period to microgravitation. In the most investigations the main attention is paid to modelling of "conflicting" vestibular-visual (VV) impacts. In other hand, in connection with the contradictory materials about the role of hemodynamic component in the development of space MS this effect of microgravitation conditions, as a rule, is not modelled in the methods of resistance enhancement to space MS. Hence in this work there was put a task to investigate the efficiency of application of different combination of VV-impacts and creation of redistribution of liquid medium of an organism in the cranial direction for increase of man resistance to space MS. For resolving this task there was used the specially developed stand, made in two modifications. This stand provided redistribution of liquid medium of an organism in the cranial direction by putting the investigated individual into the antiorthostatic position (AOP). During the rotation around the vertical axis individual was placed in such supine position on the turn table that labyrinth of the inner ear should be displaced by 8-10 centimeters from the axis of rotation to the head edge of the turn table. This increased the adequacy of vestibular apparatus irritation by gravitation and inertia forces with regard to microgravitation conditions.

Adaptation, Physiological↗

Ramsay Hunt syndrome presenting as a cranial polyneuropathy.

Ramsay Hunt syndrome (RHS) is herpes zoster of the facial nerve, frequently associated with VIII cranial nerve involvement, but on rare occasions other cranial nerves are affected as well. We present the case of a 63-year-old woman with RHS with involvement of V, VII, VIII, IX, and XII cranial nerves. The patient showed significant improvement after treatment with acyclovir and prednisolone. RHS should be recognized as a polycranial neuritis characterized by damage to sensory and motor nerves, including the facial nerve and the auditory-vestibular apparatus. Early institution of treatment with antiviral agents may help hasten healing. Involvement of the XIIth cranial nerve has not been reported previously.

Cranial Nerve Diseases↗

[Morpho-functional changes in mauthner neurons of goldfish adapted to prolonged orthodromic stimulation of acoustic nerve in vitro].

In newly-hatched goldfish the adapted state was developed using repeated short-term stimulation of the vestibular apparatus. It differed from the non-adapted state by the absence of fatigue during the turns of fishes produced by unilateral tail fin flicks in ring channel. Electrophysiological study of Mauthner neurons (MN) in adapted goldfish using the slices of medulla oblongata incubated in vitro, has shown the preservation of the amplitude of the extracellular responses after prolonged orthodromic electric stimulation of acoustic nerve, which suppressed the responses of non-adapted MN. Thus, the resistance against fatigue has developed also at the level of MN. Using electron microscopy it was demonstrated that adapted MN following the prolonged electric stimulation in vitro were characterized by the resistance of specialized desmosome-like contacts, similar to what was earlier observed in these neurons in vivo. The data obtained suggest that indirect evaluation of MN functional state in goldfish by counting the number of turns performed by it in narrow ring channel, corresponds to the direct morpho-functional assessment of MN state. This form of innate behavior of freely moving fish seems to be the result of MN excitation.

Adaptation, Physiological↗

Effect of antiorthostatic bed rest on the human body.

Head-down (-4 degrees) bedrest brings about a more rapid development of changes in haemodynamics, fluid displacement and nervous tone than traditional recumbent bed rest. Changes occurring during head-down hypokinesia have much in common with the changes typical of real weightlessness. They are characterized by phasic changes in the vascular tone. Under these conditions changes in the tone and blood-filling of the brain are important for the functional state of the vestibular apparatus.

Adaptation, Physiological↗

Transduction and adaptation in sensory hair cells of the mammalian vestibular system.

The human vestibular apparatus detects head movements and gravitational stimuli which impinge upon the mechanosensory hair cells of the inner ear. The hair cells, in turn, transduce these stimuli into electrical signals which are transmitted to the brain. These sensory cells are exquisitely responsive, signaling deflections of their mechanosensitive organelles as small as 1-2 nanometers. Remarkably, they are able to preserve this level of sensitivity even when confronted with large tonic stimuli, such as gravity. To accomplish this feat hair cells have devised a novel adaptation process that repositions the mechanotransduction apparatus on a millisecond time scale to allow high sensitivity over a broad operating range. Mechanotransduction in hair cells occurs via a direct gating mechanism in which hair bundle deflection focuses tension onto membrane-bound, cation-selective ion channels located near the tips of the hair bundle. Increased tension favors an open conformation of the channel and allows calcium to enter the cell. Elevated intracellular calcium promotes adaptation which has been hypothesized to result from the activity of a cluster of molecular motors that continually adjust the tension in the transduction apparatus. Although the transduction channel itself remains elusive, myosin Ic has recently been identified as a molecular component of the "adaptation" motor.

Adaptation, Physiological↗