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Biomedical subjects

L Ulehlová

Publications and source records attributed to L Ulehlová.

At least 19 recordsLinked to original sources
PubMed1992

Carboplatin and cisplatin ototoxicity in guinea pigs.

Ototoxic effects of cisplatin (1.5 mg/kg), cisplatin with mannitol (1.5 mg/kg cisplatin with 15 mg/kg mannitol) and carboplatin (6 mg/kg) were compared in guinea pigs treated 5 days a week for 5 consecutive weeks. Auditory thresholds were measured in awake animals by means of the compound action potential recorded from electrodes implanted near the round window. The endocochlear potential (EP) was measured in the first turn through the round window, and hair cell counts were estimated by the surface specimen technique. The most pronounced ototoxicity (threshold shifts and hair cell loss) was observed with pure cisplatin. Cisplatin with mannitol appeared to be less toxic than pure cisplatin, and carboplatin the least toxic. Even carboplatin produced significant threshold shifts, particularly at high frequencies, but they were not accompanied by hair cell loss. Values of EP were not different from those in normal control animals.

Acoustic Stimulation↗
PubMed1990

Acoustic trauma in mineworkers revealed by temporal bone necropsy.

Six selected human cochleae showing definite signs of mechanical damage caused by exposure to high intensity noise (acute acoustic trauma) are reviewed. Patterns of degeneration of cochlear hair cells were compared with the functional audiometric examinations. Tonotopic relations, mechanism of damage to the organ of Corti as well as pathological changes of the tectorial membrane are discussed.

Adult↗
PubMed1988

Light and electron microscopic appearance of the inner ear in juvenile ceroid lipofuscinosis (CL).

Inner ear cells were studied by histology, histochemistry and electron microscopy in one case of juvenile form of ceroid lipofuscinosis (Batten's disease). It was found that despite the clinically normal range of auditory acuity (nonaudiometric evaluation) there was a storage process of moderate degree with intralysosomal deposition of a lipopigment of variable ultrastructure with two patterns predominating, curvilinear and fingerprint. Storage was demonstrable in slightly variable degree in every cell type including the receptor cells of the organ of Corti and sensory cells of crista ampullaris. The cochlear neurons displayed a so far unique storage with enormous monovacuolar distension of perikarya comparable only to the lymphocytic vacuolization also present in the juvenile form of the disease. The distension of vacuoles was only partly caused by accumulation of the lipopigment mass and actually led to neuronal deterioration. The results shown here offer a new modell for functional-structural relationship and point to the urgent need of further studies of the inner ear in CL and lysosomal storage generally.

Child↗
PubMed1987

Correlative study of sensory cell density and cochlear length in humans.

In the group of 50 cochlea from 28 men aged 38-73 years a great variability in the length of the cochlear duct was found ranging from 28.0 to 40.1 mm. The variability in the number of inner and outer hair cells is not so prominent and the same holds for the variability in density. Average densities of the inner and outer hair cells decrease with increasing cochlear length. However, the long cochleae have a greater number of hair cells which indicates that long cochleae have more sensory cells in a given frequency region.

Adult↗
PubMed1987

Modified staining technique for surface preparation of the organ of Corti.

A simple technique for the staining of the inner ear tissues using toluidine blue and Ehrlich haematoxylin is described. The method is very convenient for histological evaluation of hair cell counts, for estimation of the number of scars in the reticular lamina, for observing the arrangement of stereociliary pattern and for the detection of traumatic changes after noise exposure. The method described proves to be very useful for histological examination of human temporal bones as well and makes possible an immediate evaluation of the hair cells of the human cochlea and direct correlation of the inner ear pathology with audiometric data.

Animals↗
PubMed1987

Hair cell distributions in the normal human cochlea. A report of a European working group.

Cochlear hair cell counts from individuals who had clinically normal hearing prior to their death have been plotted for various age bands as a function of the number of hair cells per millimetre against their position in the cochlea. Position has been expressed as the distance of that observation of hair cell density from the base of the cochlea, divided by the total length of the cochlea, thereby giving a proportional representation of the cochlea in the range of 0.0 to 1.0 with 20 subdivisions of 0.05. There is an age-related decrease in the number of hair cells in the normal population, and this is more marked for the outer hair cells.

Adolescent↗
PubMed1984

Involution of the auditory neuro-epithelium in a tiger (Panthera tigris) and a jaguar (Panthera onca).

Numerical atrophy of the hair cells of the organ of Corti of the inner ear in a 14-year-old tiger and a 17-year-old jaguar is described. The decrease in number of sensory hair cells is considered to represent physiological atrophy caused by the process of ageing. The findings are compared with previous observations on man, guinea-pigs, shrews, and bats. The development of the physiological involution of the hearing neuro-epithelium is discussed.

Aging↗
PubMed1983

Cochlear hair-cell populations and limits of resolution of hearing in two vespertilionid bats, Nyctalus noctula and Eptesicus serotinus.

A comparison of the population of cochlear hair cells with known hearing resolution capabilities in two species of bats (Nyctalus noctula and Eptesicus serotinus of the family Vespertilionidae) has revealed a close correlation between morphological and functional parameters. Data on number and densities of hair cells in the examined bat species are presented. Even though the species are of a comparable body size, N. noctula has a longer basilar membrane, a higher density, and hence also a higher total number of hair cells than E. serotinus. This is in good agreement with hearing resolution capabilities, which are better in N. noctula than in E. serotinus. These findings have implications on differences in feeding ecology and hunting strategies between these species.

Animals↗
PubMed1983

Stria vascularis in acoustic trauma.

Mechanical energy of noise destroys not only the organ of Corti, Reissner's membrane, and the basilar membrane but also the lateral wall of cochlear duct. The damage is characterized by ruptures running parallel to the attachment of the basilar membrane in the prominentia spiralis or sulcus spiralis externus. The other signs of injury after acoustic overstimulation are blisterlike detachments of the stria vascularis from the spiral ligament. The mechanism of injury is interpreted as the result of interaction of given mechanical properties of exposed tissues and of the kinetic energy of sound in narrow segments of cochlear duct.

Acoustic Stimulation↗
PubMed1982

The role of the spiral ligament in cochlear mechanics.

Maximum deflection of the basilar membrane (BM) in fresh guinea pig cochlea preparations attains values attaining roughly half the width of the membrane. Displacement of the BM is made possible by the elastic spiral ligament, which participates directly in dynamic processes of cochlear mechanics. That the movement is transmitted to the spiral ligament during experimental deformation of the BM by an instrument is borne out also by structural changes in the lateral wall epithelium in acoustic trauma and by vascular changes produced by chronic acoustic stress.

Animals↗
PubMed1981

Longitudinal distribution of cochlear potentials and the K+ concentration in the endolymph after acoustic trauma.

Guinea pigs were exposed to 142 dB third-octave band of noise control at 1 kHz for 1 h. At different times after exposure the endocochlear potential (EP), the anoxic negative endocochlear potential (-EP), the concentration of K+ (K+e) and microphonic potentials were recorded in scala media in four cochlear turns. The remaining hair cells were counted in each animal. Immediately after the exposure, the EP and K+e decreased evenly in all four cochlear turns and gradually returned to normal physiological values in 5-20 days. When measured 20 days after the exposure, essentially normal EP and K+e values were observed, with an apicalwards decline, which was similar to that found along the cochlea in nonexposed animals. Abnormal increased EP was observed in some animals 20 days after the exposure in the first and second turns. In contrast to positive EP and K+e values, the anoxic negative EP attained less negative values in the second turn of exposed animals, i.e., in the turn where the narrow band noise exerted the major destructive effect. An almost normal distribution of hair cells and most negative EP values were found in the fourth turn. The distribution of persistent hair cells correlated positively with the values of the anoxic negative EP and amplitudes of the microphonic potentials. It is assumed that, in addition to the difference in K+ concentration between endolymph and perilymph, the anoxic negative EP is dependent upon the functional state of the organ of Corti.

Animals↗
PubMed1980

Recovery of the endocochlear potential and the K+ concentrations in the cochlear fluids after acoustic trauma.

Intense noise stimulation (142 dB, 1/3-octave-band noise centred at 1 kHz for 1 h) causes damage mainly in the second turn of the cochlea. Several hours (3-5) after the noise exposure, the endocochlear potential (EP) was found to be very low (5.7 +/- 6.0 mV). Similarly, the K+ concentration in the endolymph (Ke+) had decreased to low values (18.9 +/- 9.5 mM). The return of EP and Ke+ to normal values took 5-20 days. In contrast to the Ke+ changes, the perilymph K+ concentration (Kp+) increased slightly after the noise exposure to 4.5 +/- 1.7 mM and returned to normal values one day after the exposure. Differences were found in the time course of the EP, Ke+ and Kp+ changes after the arrest of ventilat ion when animals with acoustic trauma were com,ared with normal healthy individuals. The anoxic EP in noise-exposed animals never decreased to values more negative than -20 mV. The results imply that the inner ear mechanisms maintaining positive EP, Ke+ and Kp+ are severely damaged after acoustic trauma and that their function is restored in 5-20 days. With respect to some parameters (decrease of the EP during anoxia, the value of anoxic negative EP, EP overshoot after reventilation) the inner ear mechanisms are, however, still abnormal.

Acoustic Stimulation↗
PubMed1980

Comparative method for the study of structural damage in acoustic trauma.

The traumatic dose 50 (TD50), similar to the lethal dose (LD50) widely used in pharmacology, was determined in guinea pigs for varying intensities and varying durations of exposure to a band of noise. The method proposed permits the comparison of results in studies of acoustic trauma caused by noises of various characteristics in different species of experimental animals.

Animals↗
PubMed1978

Effect of high-intensity sound on cochlear microphonics and activity of inferior colliculus neurons in the guinea pig.

The input-output functions of cochlear microphonics (recorded from the round window) in guinea pigs exposed briefly to high-intensity sound (2 kHz, 130 dB, 30 min) were shifted toward higher intensities by about 15 dB in comparison with normal animals. 2-4 h after the exposure this shift decreases to 10 dB. The response characteristics of the inferior colliculus neurons were compared under similar conditions. Thresholds at the characteristc frequencies (CF) measured 2-4 h after exposure, were raised by 30-50 dB, a higher threshold increase was observed at frequencies from 5-7 kHz. 48 h after exposure the thresholds approached those obtained in normal animals. There was no pronounced hair cell loss after exposure. It is assumed that in addition to the impairment of sound transduction in hair cells there may be a specific effect of high-intensity sound exposure on neuronal transmission in the auditory pathway.

Animals↗
PubMed1978

Idiopathic hair cell loss in the guinea pig.

An incidence of specific, marked sensory cell loss affecting 12--88% of the outer hair cells in the third cochlear turn was found in a group of 130 healthy, coloured, intact guinea pigs divided into three age groups (6 weeks, 7 months, and 3 years). The pathological findings were compared with a known physiological norm. At 7 months, the disorder occurred in 8% of the animals, whereas at 3 years 30% were involved. The etiology of the above finding is at present still obscure.

Animals↗