Glycine-like immunoreactivity in the rat auditory pathway.

From neurophysiological and biochemical studies it has been suggested that glycine can function as a major inhibitory neurotransmitter in the central nervous system of mammals. In the present study, anti-glycine antiserum was obtained from rabbits immunized with glycine conjugated to rabbit serum albumin via glutaraldehyde and purified by affinity chromatography. The antibody thus obtained was found specific for glycine as determined by an enzyme immunoassay system. The immunocytochemical distribution of glycine in the auditory tract and internal ear was investigated with the antibody. In the central auditory pathway, glycine-like immunoreactivity was mainly located in the ventral and dorsal cochlear nuclei, trapezoid body, lateral lemniscus and inferior colliculus. In the labyrinth, immunoreactivity was detected in the vestibular ganglion and the supporting cells of the crista ampullaris and the organ of Corti, but not in the spiral ganglion. These findings suggest an important role of glycine in the auditory and vestibular pathways.

Inner ear lidocaine concentrations following iontophoresis.

This study has established the feasibility of measuring perilymph lidocaine levels after iontophoresis for local tympanic anesthesia in the rabbit model. A subsequent study may now be performed to produce a valid, dose-response curve correlating perilymph lidocaine levels and cochlear responses. In this manner the effects of and safety of lidocaine iontophoresis for tympanic anesthesia can be determined with certainty. After intravenous sedation, eight rabbits underwent iontophoresis followed by diagnostic vestibulotomies. Perilymph samples were taken and analyzed for lidocaine levels. Significant amounts of perilymph lidocaine were found in both the intact and perforated tympanic membrane groups. In the perforated tympanic membrane group, the perilymph lidocaine level was eight times that of the intact tympanic membrane group. Future studies to determine the dose-response relationship of perilymph lidocaine to cochlear responses are now possible. Thus, the safety of lidocaine iontophoresis and the degree of inner ear toxicity of lidocaine can be established quantitatively.

Type II collagen distribution in rodents.

The anatomical distribution of type II collagen in animal ears was studied by immunohistochemical techniques, using defined monoclonal antibodies to type II collagen. Type II collagen was observed in the cartilage plate of the auricle and external auditory meatus, tympanic annulus, lamina propria of tympanic membrane (pars tensa), interossicular joints, stapes footplate, eustachian tube cartilage, enchondral layer and globuli interossei of the otic capsule, Rosenthal canal, cribriform base, osseous spiral lamina, spiral ligament, limbus, tectorial membrane, semicircular canal membrane and subepithelial layer of the ampullary crista, utricular and saccular maculae, and the endolymphatic duct and proximal part of the sac.

Somatostatin (somatostatinlike) immunoreactive cells in the human inner ear.

Certain epithelia of the human inner ear and human endolymphatic sac display somatostatin and/or somatostatin-like immunoreactivity. Histologic sections from 13 human temporal bones and from 15 endolymphatic sacs were studied using the unlabeled antibody peroxidase-antiperoxidase technique. The somatostatin and/or somatostatin-like immunoreactive cells were located exclusively in the covering epithelium of the spiral prominence and in the epithelium of the intermediate and rugosal part of the endolymphatic sac. In the epithelium of the spiral prominence and endolymphatic sac, secretory granules of the same size and appearance as those of intestinal or pancreatic somatostatin-producing cells were demonstrated ultrastructurally. The findings are consistent with a local exocrine, paracrine, and/or endocrine system of the inner ear.

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.

Observations on normal and degenerating human otoconia.

Specimens of human otoconia obtained from autopsy material and representing various stages from fetal to advanced old age, were studied by microdissection, scanning electron microscopy, electron microprobe analysis, and x-ray powder diffraction. The typical adult otoconial configuration is a cylindrical, finely serrated body with pointed ends; crystallographically, it corresponds to a single crystal of calcite. Other, less numerous typed include jointed otoconia, pure rhombohedrons and multifaceted, presumably immature forms. Many otoconia achieve the adult configuration during fetal development. The multifaceted otoconia are most numerous, and the rhombohedrons proliferate, during childhon in the young adult, but saccular otoconia are the larger. In middle and advanced age the otoconia decrease in number, especially in the saccule. Saccular otoconia degenerate progressively in a posteroanterior direction across the macula; they assume a specific, fibours, hollowed-out appearance, which is not duplicated by either chemical etching or autolysis. Neogenesis and growth of otoconia appear to occur postnatally, with different characteristic growth potentials for those of the saccule and the utricle. Age-related saccular otoconial degeneration appears to involve the organic material, which disappears either before or simultaneously with the mineral substance.

Analysis of trace elements in the human labyrinth by using proton microprobe.

The concentration of zinc in the spiral tract is age-dependent. The accumulation of zinc starts at the bone surface towards the fundus of the internal auditory meatus and continues throughout the whole thickness of the separating wall to reach in advanced age the bone surface towards the basal coil of the cochlea. The concentration of calcium decreases with age. These findings prove our previous histological and densitometric as well as macroscopical investigations of this region.

Retinol and retinyl ester in separated structures of the guinea pig inner ear.

Chemical separation of different vitamin A derivates in inner ear extracts was performed by means of high pressure liquid chromatography (HPLC) with fluorescence and UV detection. For more accurate site identification the membranous cochlea was dissected and the basilar membrane, the spiral ligament and the stria vascularis were isolated for analysis. Retinyl esters were found in the basilar membrane at a concentration of 11.4 +/- 5.9 micrograms/g dry weight, a high concentration compared with that in other tissues of other organs. The spiral ligament contained retinyl esters at a lesser concentration and no retinyl esters were found in the stria vascularis. Retinol was not detected in the spiral ligament or basilar membrane but was found in the stria vascularis at a concentration of 1.2 +/- 0.8 micrograms/g. Retinyl palmitate and retinyl stearate were identified. This investigation shows that vitamin A forms retinyl esters with long-chain fatty acids in the basilar membrane in high concentrations relative to other organs and in greater quantity than in other sites in the inner ear.

Carbohydrate content of the endolymphatic sac. A histochemical and lectin-labelling study in the Mongolian gerbil.

A secretory activity has recently been attributed to the endolymphatic sac (ES), as a possible way to contribute to the fluid balance of the entire endolymphatic compartment. Previous histochemical studies have indicated the existence of carbohydrate complexes in the secretory product, both neutral and acidic in nature. A thorough analysis of these compounds in the gerbilline ES was carried out using both transmission electron microscopic (TEM) histochemistry, using dialyzed iron and periodic acid--chromic--silver staining techniques, as well as immunoflourescence with fluorescein-labelled lectins (FITC-lectins). N-acetylglucosamine was found to be one of the major carbohydrate components both of the epithelial layer of the ES and of the luminal precipitate. Proofs for a local secretory activity and its intracellular pathway are presented, suggesting to be involved in the regulation of pressure and volume of inner ear fluids.

Substance P-like immunoreactivity in the rabbit inner ear.

The auditory and vestibular sense-organs of the rabbit were examined for the presence of substance P(SP) by an immunohistochemical technique using a monoclonal SP-antibody. Between 30 and 40 per cent of the cells of the vestibular ganglia and about 50 per cent of the spiral ganglion cells innervating the extreme basal part of the cochlea showed SP-like immunoreactivity. The neural elements in the vestibular sensory epithelia, notably the calyx-formed nerve terminals of type I sensory cells of the maculae, also showed strong SP-like immunoreactivity. The findings suggest the possibility of a modulator or transmitter role for SP in the inner ear function.

[Detection of immunoglobulin in the inner ear tissue by PAP method].

The distribution of immunoglobulins IgG, IgA and IgM in the inner ear tissue from a patient who died of lung bleeding followed after sepsis was studied, and also the normal guinea pig inner ears and the inner ear disorders induced by Kanamycin injection were studied for the distribution of IgG. The temporal bones were fixed in formaldehyde, decalcified in EDTA and embedded in paraffin. The PAP method was used for the demonstration of the immunoglobulins. In both the human inner ear tissue and the normal control inner ear tissue of the guinea pigs deposits of IgG were found in the sensory organs and the endolymphatic sac, however, in the stria vascularis was slight. The severe damaged inner ears induced by Kanamycin the remarkable decreased deposits of IgG were found in the cochlea, but in the endolymphatic sac the remarkable increased deposits of IgG were found. No IgA and IgM were found in the human inner ear tissue.