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Biomedical subjects

H Felix

Publications and source records attributed to H Felix.

At least 19 recordsLinked to original sources
PubMed1992

Morphometric analysis of the cochlear nerve in man.

Fiber diameters were analyzed in the meatal segment of the cochlear nerve from 7 temporal bones obtained from 7 patients. Two patients had normal hearing for their age. Two had sustained noise exposure and one had presbyacusis of predominantly neural type. The cochleae displayed characteristic degeneration patterns. The other two manifested hearing loss of unspecified type. The fiber diameters ranged from 0.5 to 11 microns. The diameter distribution was unimodal in all seven nerves. The means of the diameters ranged from 4.2 to 5.5 microns. They were significantly different between patients with age-related normal hearing on the one hand and patients with noise induced hearing loss and neural presbyacusis on the other. The findings are discussed in relation to changes in nerve conduction speed and hearing loss; a possible correlation between the fiber diameter distribution and the tonotopical arrangement of the cochlea is suggested.

Cochlear Nerve↗
PubMed1992

Multicentre evaluation of the temporal bones obtained from a patient with suspected Menière's disease.

A multicentre study of the inner ears of an 88-year-old patient with vertiginous spells and severe hearing loss in the left ear was performed, employing regular and block surface preparations, light and electron microscopy with qualitative and quantitative evaluation of the cochlear and vestibular nerves. There was severe hydrops of the left cochlea and saccule. Reissner's membrane extended into the vestibule and herniated into the perilymphatic space of the non-ampullated end of the horizontal canal. Furthermore, the short canal connecting the posterior ampulla with the utricle had a small, exceedingly thin balloon-like expansion. Only slight hydrops limited to the cochlea was found in the right ear. Sensorineural degeneration was much more pronounced in the left cochlea than in the right. The number of cochlear and vestibular nerve fibres was greatly reduced in the left ear where more fibres with degenerative changes were present. In both specimens the number of myelinated nerve fibres in osseous spiral lamina was smaller than that in the cochlear nerve in the internal auditory canal. Changes occurred in the endolymphatic sacs but were considered non-specific. In this case severe, apparently progressive hydrops and sensorineural degeneration, characteristic of Menière's disease, were associated with atypical onset of clinical symptoms at a late age.

Aged↗
PubMed1991

New aspects of facial nerve pathology in temporal bone fractures.

Electron microscopic examination of intratemporal facial nerve segments removed from 12 patients with persisting facial paralysis following temporal bone fractures revealed that traumatic injury at the geniculum induces retrograde degeneration through the labyrinthine and distal meatal segments of the facial nerve. Fibrosis may occur in the traumatized labyrinthine segment and block regenerating motor fibers. The surgical treatment of traumatic facial nerve injuries should be aimed to avoid or eliminate fibrosis within the labyrinthine segment of the Fallopian canal.

Biopsy↗
PubMed1990

Quantitative analysis of cochlear sensory cells and neuronal elements in man.

The myelinated radial fibres in the osseous spiral lamina and the myelinated fibres in the cochlear nerve in the internal auditory canal as well as the sensory cells were counted in cochleae from 15 dissected temporal bones from 8 patients. Light microscopy was carried out on semithin sections of epoxy resin embedded tissue. Audiometry had been performed within 6 months prior to death. Three patients had normal hearing for their age group, 2 had slight presbyacusis and the remaining 3 had sustained noise injury. All specimens clearly had fewer fibres in the spiral lamina than in the internal auditory canal. The cochleae from patients with normal hearing for their age group had a difference in the nerve fibre counts of up to 34%. A case of sensorineural presbyacusis showed 31%, and a case of neural presbyacusis, 47% difference. The greatest difference was found in a case of acoustic trauma, the range in this group being between 25% and 55%. The lower the number of fibres in the spiral lamina, the greater was the difference in all but two specimens. A slow retrograde degeneration, i.e. beginning in the peripheral process of the cochlear nerve, could be an explanation for these findings.

Aged↗
PubMed1990

Ultrastructural aspects of the human peripheral vestibular system.

The sensory epithelia from the membranous labyrinths of 4 patients were examined by transmission electron microscopy. The distribution ratio of type 1 to type 2 cells was recorded, compared for each sensory area and correlated with age. An ultrastructural assessment confirmed generalized patterns consistent with autolytic and preparation artefact, viz. calyceal dilatation, cytoplasmic protrusions and some sensory hair loss. More specific features, i.e. lipofuscin accumulation, membrane-bound inclusions and neural degeneration were consistent with pre-mortem pathological change. In 2 patients, total nerve fibre counts of 15,766 and 19,741 were obtained. Total fibre counts correlated with the sensory cell density of the innervated areas. Differential counts of the superior and inferior vestibular nerves suggested that there was a reduced number of fibres in the superior division of both patients, in comparison with established normative data. Morphometric analysis of the constituent fibre diameters revealed a skewed distribution with a modal value of 6 microns for both patients.

Aged↗
PubMed1990

Observations on the pattern of sensorineural degeneration in the human cochlea.

Cochlear sensory and neural degeneration was examined in nine pairs of human temporal bones fixed by perilymphatic perfusion, using phase-contrast and electron microscopy. Four pairs, three from females, had only slight sensorineural degeneration, limited to the very basal end of the cochlea. A predominantly neural degeneration was identified in a 54-year-old male. The process was bilateral, asymmetrical, uneven, and involved the entire length of the cochlea with several circumscribed areas of severe nerve degeneration. One case had mild, diffuse sensorineural degeneration in the lower half of the basal turn characteristic of presbyacusis. The other three pairs, all from males, revealed sensorineural degeneration patterns associated with noise injury and were remarkably similar to or almost identical with cochleas described previously. There was a good correlation between the presence of supporting cells and the survival of nerve fibres in the osseous spiral lamina in the corresponding area. In one cochlea, however, the degeneration of only inner hair cells in a small area was associated with complete nerve degeneration in the corresponding sector of the spiral lamina. Giant cilia were frequently seen in the apical turn.

Adult↗
PubMed1990

[Histopathology of the vestibular nerve in Menière's disease].

Histological and morphometrical investigations of the vestibular nerve were performed on surgical specimens from 19 patients suffering from Ménière's disease and on 5 autopsy preparations from patients without inner ear disease. The number of lipofuscin granules and vacuoles in the ganglion cells of specimens from Ménière patients was not increased compared with control specimens of a similar age, nor did the amount of endoneuronal connective tissue in the vestibular nerve specimens differ between the two groups. The density of capillaries in Scarpa's ganglion and vestibular nerve was significantly increased in the Ménière patients compared with the control specimens. Furthermore, the ratio of nerve fibres with a larger diameter was higher in specimens from Ménière patients than in control preparations. There was no difference in the density of myelinated fibres between the two groups.

Capillaries↗
PubMed1988

Effect of ligating peripheral branches on facial nerve regeneration.

Bilateral transection and reanastomosis of the main trunk of the facial nerve was performed on 18 rats. On one side of each rat, all peripheral branches except the mandibular branch were ligated with silk suture and divided distal to the ligatures. Axon counts after 1, 3, and 6 months showed a statistically significant increase in the number of axons in both the mandibular branch and the main trunk on the side with the peripheral ligation. These data indicate that peripheral branch ligation is a useful adjunct in facial nerve rehabilitation.

Action Potentials↗
PubMed1988

[Efficacy of Ro 15-0216 against human strains of Trypanosoma gambiense maintained in rodents. A preliminary study].

The 2-nitro-imidazole derivative Ro 15-0216, closely related to benznidazole used for the treatment of South American trypanosomiasis (T. cruzi) proved effective against T. brucei brucei and T. brucei rhodesiense in rodents and sheep models. Diffusion in CSF is large in dogs and sheep. We studied splenectomised or immunodepressed mice and rats, infested with T. brucei gambiense human strain T-M1 isolated from a Gabonese patient with sleeping sickness. 2 groups of 5 mice were treated with oral doses of 50 mg/kg and 100 mg/kg for 3 days. 3 mice were injected with 10 mg/kg intraperitoneally. 3 rats were given 50 mg/kg orally for 2 days. 3 rats were injected with 25 mg/kg, 4 rats with 10 mg/kg, 2 rats with 100 mg/kg intraperitoneally. 13 animals were "controls". A dose of 10 mg/kg was rapidly active against the parasites circulating in blood. The diffusion in CSF was not studied. No side effects have been observed. 24/25 treated rodents were in good health without parasites in the blood at Day 12.

Acetanilides↗
PubMed1988

The influence of climatic factors on the nasal mucosa of rats.

The influence of indoor climate on goblet cells and intraepithelial glands of nasal mucosa was analysed. A cold and heat adapted group of twenty rats were compared with a neutral adapted group after eight weeks of climatic exposure. There was a decrease of density of the goblet cells and the intrapeithelial glands in cold adapted rats. It is suggested that the adaptive changes of the mucous membranes of the rats may be correlated with the increased ventilation rate in the cold.

Animals↗
PubMed1988

[Histological study of the binding of Polycel and Ceravital implants to the stapes footplate in rabbits].

Five Polycel and five Ceravital implants were interposed between the stapedial footplate and the tympanic membrane in 10 rabbits. Four to 7 months later the connection of the prostheses to the stapes was histologically examined by temporal bone sections. The union of both types of prostheses to the stapedial footplate was achieved by remnants of crura, middle ear mucosa and connective tissue. Histology revealed a more stable connection of the Polycel prosthesis to the stapedial footplate.

Animals↗
PubMed1987

A morphological study of the effect of the Cavitron ultrasonic surgical aspirator system near human peripheral nerves.

The Cavitron ultrasonic surgical aspirator system was used to clear superficial tissue from the greater auricular nerve in four human subjects. Following stimulation, the nerves were removed together with an untreated section and processed for examination by light microscopy. Significant damage had been sustained by these nerves, which was not apparent in the control sections. Disruption of the perineurium, intraneural hemorrhage, endoneural edema, and degenerative changes of the myelinated nerve fibers were seen. Damage to neural tissue was evident 0.5 to 1.5 mm in advance of the point of contact with the cutting tip.

Edema↗
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↗
PubMed1987

Methodological aspects of quantitative study of spiral ganglion cells.

The literature contains little numerical information on the population of spiral ganglion cells from normal-hearing adults. We present a method for quantitative analysis of spiral ganglion cells. We used not only the total counts of the neurons but also divided the spiral ganglion into four segments as described by Otte et al. Nine perilymphatic perfused temporal bones from 5 adult patients with normal hearing for age were examined. The largest population of spiral ganglion cells was always in segment II and fewest in segment I. There is no correlation between the total count and the length of the cochlea.

Adult↗
PubMed1987

Ultrastructural findings on human Scarpa's ganglion.

The morphology of human Scarpa's ganglion from two surgically removed specimens as well as from four autopsy preparations from patients without clinical evidence of vestibular dysfunction was investigated. Ganglion cell circumference varied between 45 and 160 microns. More than half of the nerve cells ranged between 90 and 110 microns. The arrangement of ganglion cells, nerve fibres and endoneural connective tissue appeared better preserved in autopsy preparation than in biopsy specimens. Electron microscopy revealed that in half of the investigated specimens, neuroglial tissue was present as far distal as the vestibular ganglion. Almost all ganglion cells were surrounded by one or several layers of satellite cells, and did not reveal myelination. From the present study we cannot predict if neuronal function in human beings differs from that in other animals, although morphological differences do exist.

Adult↗