Biomedical subjects

M Anniko

Publications and source records attributed to M Anniko.

At least 235 records · Page 13Linked to original sources

PubMedDate not supplied

Calbindin-D28K localization in the primate inner ear.

The distribution of one of the calcium-binding proteins, calbindin-D28K (CB-D28K), was studied in the adult human and squirrel monkey inner ear by means of immunocytochemical methods. Inner and outer hair cells in the organ of Corti and vestibular hair cells showed CB-D28K immunoreactivity, though some vestibular hair cells were devoid of immunoreactivity. In the spiral and vestibular ganglion, immunoreactive cells were found in both the squirrel monkey and human. The present results indicate that CB-D28K is localized within afferent neuronal components in these sensory organs and may regulate Ca++ levels for optimal neurotransmission in the primate auditory and vestibular systems. This study also provides evidence of two nonneuronal localizations of CB-D28K in the squirrel monkey. Subpopulations of fibrocytes in the spiral ligament and vestibular end organs were enriched with CB-D28K, suggesting that these cells are possibly equipped with the function to regulate Ca++ concentration in the perilymphatic fluid. In the maculae, many CB-D28K-immunoreactive particles were found in the otoconial membrane, indicating that CB-D28K may participate in the formation of otoconia.

Adolescent↗

PubMedDate not supplied

Three-dimensional organization of cytoskeletons in the vestibular sensory cells.

The cytoskeletal organization of the guinea pig vestibular sensory cells was investigated employing the saponin perfusion method using scanning electron microscopy as well as immunohistochemical technique. The intermediate filaments were demonstrated in the sensory cells. They were usually seen surrounding the nucleus and extending through the cytoplasm which connected the nuclear membrane to the plasma membrane, cuticular plate or other cytoorganelles. These findings may suggest that the intermediate filaments provide mechanical support to the cell and its nucleus. Microtubules were found mainly in the supranuclear portion of the cells and run parallel to the main axis of the cell body, which is directly connected to the cuticular plate. These findings may suggest that the microtubules provide mechanical support to the cell and may be closely related to the sensory cell transduction system. The actin filaments were densely packed in the site of the cuticular plate. They also distributed throughout the cytoplasm, which appeared as a dense network in the periphery region. These findings support the idea that the actin filaments could be responsible for sensory cell transduction as well as to give mechanical strength to the surface of the cell and enable the cell to change its shape and move.

Actins↗

PubMedDate not supplied

Alpha-bungarotoxin inhibits outer hair cell motility in situ.

The effect of two substances (alpha-bungarotoxin, alpha-BGTX, a small protein, and the local anesthetic bupivacaine hydrochloride) with an assumed effect on outer hair cell (OHC) motility were analyzed after exposing the cochlea via the round window membrane. Electrophysiological measurements were performed with a very narrow frequency-specific gating (+/- 100 Hz) technique to determine auditory brainstem response (ABR) thresholds, including ABR-based frequency tuning curves. Exposure to alpha-BGTX gave a minor improvement in thresholds, interpreted as a facilitation of OHCs, i.e. releasing their efferent inhibitory control, whereas exposure to bupivacaine hydrochloride impaired ABR thresholds, possibly due to immobilization of OHC motility via the lateral cell membrane. Our results are consistent with the hypothesis that efferent influence on the cochlea may be linked with a modulation of the mechanical function of OHCs. We can now postulate that there is in vivo evidence that acetylcholine exerts its effect at the OHCs via an alpha-BGTX alpha-BGTX binding acetylcholine receptor.

Acetylcholine↗

PubMedDate not supplied

Expression of subtypes NF-L, NF-M and NF-H of neurofilament triplet proteins in the developing rat inner ear.

The expression of each subtype (NF-L, NF-M and NF-H) of neurofilament (NF) triplet proteins in the developing rat inner ear was analysed using the immunofluorescence method (FITC). On the 15th gestational day (GD), immunostaining of NF subtypes did not occur in the otic region. On the 18th GD, positivity for NF-L and NF-M occurred in nerve fibres in both the sensory and the subepithelial layers of the inner ear but was lacking for NF-H. At 4 days after birth immunoreactivity was present for each NF subtype but with topographic differences in their distribution. The cell bodies of (different?) subpopulations of vestibular and spiral ganglion cells were immunostained with monoclonal antibodies for NF-L and NF-M, but a subpopulation of both vestibular and spiral ganglion cells showed immunoreactivity for all three NF subtypes. The vestibular nerve fibres and ganglion cells evidenced stronger positivity than cochlear nerve fibres and spiral ganglion cells. This study confirms that the cytoskeletal maturation of inner ear nerve fibres precedes the onset of at least the auditory function by several days.

Animals↗

PubMedDate not supplied

Auditory epithelial migration. IV. Light- and scanning electron-microscopic studies of the tympanic membrane and external auditory canal in the mouse.

The fine structures of the tympanic membrane and external auditory canal (EAC) were observed in the mouse under both the light microscope and scanning electron microscope. According to the differences in morphological features of the epidermis and epidermal cells, they were grossly classified into 8 types of region: (1) the region of the handle of the malleus, (2) the intermediate region of the pars tensa (PT), (3) the annular region of the PT, (4) the region of the pars flaccida, (5) the annular region of the anterior, inferior and posterior walls of the EAC, (6) the osseous region of the anterior, inferior and posterior walls of the EAC, (7) the region of the upper wall of the EAC and (8) the cartilaginous region of the anterior, inferior and posterior walls of the EAC. The specific structure "finger-like projections' was visualized throughout in the annular region of the EAC. The morphology of the region of the upper wall of the EAC was almost identical with that of the cartilaginous region of the anterior, inferior and posterior walls of the EAC.

Animals↗

PubMedDate not supplied

Auditory epidermal cell migration. V. Transmission electron-microscopic study of tympanic membrane and external auditory canal in the mouse.

The morphology of the tympanic membrane (TM) and external auditory canal (EAC) in mice was examined by transmission electron microscopy, in seven different regions: the handle of the malleus (HM) region, the intermediate and annular regions of the pars tensa (PT), the region of the pars flaccida (PF), the annular and osseous regions of the EAC and the cartilaginous region of the EAC. Each region displayed its own unique findings. In most regions of the TM and EAC-except the intermediate region of the PT-basal layer cells formed cytoplasmic processes (CPs) on their basal surface and adhered to the basement membrane (BM) by means of hemidesmosomes (HDs). This observation may suggest the presence of stem cells. In contrast, basal cells in the intermediate region of the PT did not extend any CPs from the basal surface but attached to the BM by a few characteristic spots of HD-like density but lacking the characteristics of HDs. It is concluded that stem cels are not present there and that basal cells connect loosely with the BM, thus providing the necessary morphological conditions to migrate laterally toward the annular region. The outermost layer of the epidermis in the annular region of the EAC showed numerous cytoplasmic projections (so-called 'finger-like projections'), representing keratinization and desquamation of epidermal cells (keratinocytes). These projections are believed to be the terminal differentiation of epidermal cells originating from the general centre in the HM region of the PT. The epidermis of the PF is an extension of the upper wall of the EAC, but the two regions differ morphologically.

Animals↗

PubMedDate not supplied

Image analysis of neurofilament immunoreactivity in human spiral ganglion.

Computer-assisted image analysis was used to study the immunoreactivity to NF-L, NF-M and NF-H in human spiral ganglion cells. The concentrations, represented by the relative mean grey of NF-L, NF-M and NF-H, were calculated and compared. The cell-area mean-grey correlations for NF-L, NF-M and NF-H were analysed and calculated, showing that NF-M is more specific to the larger cells (type 1?) and NF-H is more specific for the smaller cells (type 2?), while NF-L is non-specific for cell size. These findings confirm several previous assumptions by providing a quantitative basis. We conclude that image analysis is a useful-even essential-tool for the analysis of immunostained temporal bone sections.

Adolescent↗

PubMedDate not supplied

Localization of nitric oxide synthase isoforms (I, II and III) in the endolymphatic sac of the guinea pig.

The localization of nitric oxide (NO) synthase (NOS) isoforms was examined in the endolymphatic sac (ES) of the pigmented guinea pig by indirect immunohistochemistry. The cytoplasm of the epithelial cells in the ES showed both NOS-I and -III immunoreactivity, whereas their nuclei appeared negative. NOS-III staining was also observed in the endothelial lining of the blood vessels. These findings support the hypothesis that NO in the epithelial cells may play an important role for the active intracellular transport of the endolymph and ion. NO may also be crucially involved in the regulation of ES blood flow. Immunostaining for NOS II revealed no reactivity in general, while in lipopolysaccharide-inoculated animals, intense reactivity was found in the cytoplasm of the ES epithelial cells as well as macrophages in the lumen. Thus it has been indicated that NO also may play an important role in the immunodefensive mechanisms in the ES.

Animals↗

PubMedDate not supplied

Elemental composition of the developing inner ear.

The elemental composition of the inner ear fluid-filled compartments has been analyzed using the x-ray energy dispersive technique (CBA mouse). Special attention has been focused on the maturation of endolymph. A few days before and after birth the relative peak intensity of potassium (RK) in the vestibular endolymphatic compartment was slightly surpassing that in the cochlear part of the labyrinth. From the fourth day after birth (DAB) a rapid increase occurred concerning the RK. The highest RK was found in the endolymphatic space in the basal part of the cochlea followed by that in the vestibular endolymph. The lowest RK was measured in endolymph of the apical part of the cochlea. These obvious differences were abandoned already on the sixth DAB. A mature composition of endolymph was reached on the eighth DAB. The present technique does not allow analyses of differences between cochlear and vestibular endolymph with regard to minimal shifts.

Animals↗

PubMedDate not supplied

Development of intercellular junctions in the vestibular end-organ. A freeze-fracture study in the mouse.

The intercellular junctions and the tight junctions in particular are considered to be of great importance for the function of the inner ear. The two fluid compartments of the inner ear, the perilymphatic space and the endolymphatic space, need to be effectively separated from each other in order to maintain the ionic gradients between the two. The tight junctional structures have been described in mature animals of several species. In the present article the development and maturation of the intercellular junctions are described in the mouse embryo. Junctional elements are already present in the 12th gestational day otocyst. Over the next few days, the otocyst is differentiated into a cochlear portion and a vestibular portion. The tight junctions in the vestibular portion gradually attain their mature appearance. It seems as if the tight junctions of the supporting cells develop slightly faster than those of the hair cells. At the time of birth, all epithelial cells have obtained mature appearance. The tight junctions are fully developed on the supporting cells as well as the hair cells. Small gap junctions are present in the 14th gestational day specimens. Two days later the hair cells and the supporting cells are well differentiated; small to medium-sized gap junctions are present only on the supporting cells at this stage. At the time of birth larger gap junctional aggregates have developed on the supporting cells.

Animals↗

PubMedDate not supplied

Development of the sensory receptor cells in the utricular macula.

Normal CBA mice were timed for the developmental stage by the vaginal plug technique. The day of copulatory plug observance was designated as gestation day one. The developmental characteristics of the utricular macula sensory epithelium is described on an ultrastructural level from the 15th to the 19th day of gestation (approximate day of birth). The following pertinent observations are reported: (1) the formation of stereocilia begins prior to the 15th day and continues to approximately the 18th day, (2) the formation of the stereocilia suggests a mechanism of gradual transformation of existing cell surface microvilli, (3) the onset of the genesis of stereocilia precedes neuronal contact and cuticular plate formation, (4) stereocilia rootlets are forming before cuticular plate formation, (5) utricular sensory hair cells have undergone significant ultrastructural differentiation prior to the development of synaptic contacts, and (6) nerve chalice formation of type 1 sensory cells begins on the 18th day and is still incomplete at birth.

Animals↗

PubMedDate not supplied

Damage to the stria vascularis in the guinea pig by acute atoxyl intoxication.

The aim of the present study was to show the morphological degeneration at the ultrastructural level, after damaging the stria vascularis experimentally. The acute lesions, after acute atoxyl intoxication, occur after about 12 hours, and begin as a degeneration of both the marginal and the intermediate cells, whereas the basal cells remain mainly unaffected. The severely damaged marginal or intermediate cells may become loosened from the stria vascularis and rejected from it into the endolymphatic space. Under such conditions the basal cells may line the surface facing the endolymph, although this occurs very rarely. Intially, there may be a slight bulging of Reissner's membrane, but soon the membrane becomes depressed, and sometimes a total collapse occurs, with Reissner's membrane flattened over the tectorial membrane against the organ of Corti. It is only seldom that Reissner's membrane touches the strial surface. Mitochondrial degeneration with formation of intramitochondrial inclusion bodies is an interesting early finding in the damage pattern.

Animals↗

PubMedDate not supplied

Damage to Reissner's membrane in the guinea-pig cochlea following acute atoxyl intoxication.

The ototoxic effects of the arsenic compound atoxyl has been earlier demonstrated by Anniko & Wersäll (1975) in the stria vascularis of the guinea pig cochlea. The aim of the present investigation was to study the morphological degeneration at the ultrastructural level after damaging the Reissner's membrane experimentally. In acute atoxyl intoxication the first signs of degeneration appear after approximately 12 hours. After 24 hours, the membrane may be markedly degenerated. Both the epithelial and mesothelial cells become vacuolized, the mitochondria lose their internal structure and become swollen, and lipid granules are found in the cytoplasm. Mesothelial cells are damaged to a lesser extent than the epithelial cells in the same specimen.

Animals↗

PubMedDate not supplied

The cytochochleogram in atoxyl-treated guinea pigs.

The earliest atoxyl induced changes in the cochlea appeared in the upper and medial parts of the 4th coil, whence the changes spread progressively downwards towards the round window, the extent of the changes depending on the amount of atoxyl administered and the duration of the treatment. The inner hair cells were more resistant to the effects of atoxyl than the outer hair cells which were affected first. The sensory cells in the 2nd and 3rd rows appeared more sensitive than the outer hair cells in the first row.

Aminobenzoates↗

PubMedDate not supplied

Afferent and efferent nerve terminal degeneration in the guinea-pig cochlea following atoxyl administration.

Atoxyl causes destruction of both afferent and efferent nerve endings. Degeneration of afferent nerve terminals occurred even though the adjacent hair cell had a normal ultrastructure. The degeneration of the efferent nerve endings took place at the same time as the adjacent cell disintegration. Earlier studies on the effects of atoxyl have shown that it also induces damage to the stria vascularis and Reissner's membrane, thus interfering with endolymph metabolism (Anniko & Wersäll, 1975; Anniko, 1975a, b). The afferent nerve terminals may be more sensitive to changes in the environment (endolymph) than are the surrounding structures, including efferent nerve endings, hair cells and supporting structures, and would therefore be the first structures to disintegrate.

Aniline Compounds↗

PubMedDate not supplied

Surface structure of stria vascularis in the guinea pig cochlea. Normal morphology and atoxyl-induced pathologic changes.

The normal cell surface of the hexagonal epithelial (marginal) cells covering the stria vascularis is characterized by numerous microvilli and a few depressions. The cells at the spiral prominence are similar to the epithelial cells of the stria vascularis but are more spindle shaped and without depressions on the surface. Atoxyl treatment results in damage to the epithelial cells of the stria vascularis by loss of microvilli and depressions. Later during the degeneration, protrusions from the cell surface occur and the cell borders become fragmented. The cells of the spiral prominence are far less damaged. In advanced stages of strial damage great herniations including several adjacent cells may balloon out into the endolymphatic space.

Aniline Compounds↗

PubMedDate not supplied

Experimentally (atoxyl) induced ampullar degeneration and damage to the maculae utriculi.

Atoxyl administration to guinea pigs may cause vesicular degeneration of both the secretory and the sensory regions of the cristae ampullares and macula utriculi. Some of the severely damaged secretory cells were even expelled from the surface into the endolymphatic space. The nerve chalices of type I hair cells disintegrated. The degeneration of the secretory region will thus block the endolymph circulation and the electrolyte balance is likely to collapse. Whether hair cell degeneration can best be explained on this basis (indirect atoxyl effect) or by a direct action of atoxyl on the hair cells and the nerve chalices of type I hair cells is discussed.

Aniline Compounds↗

PubMedDate not supplied

Morphological changes of labyrinthine blood vessels following metal poisoning.

Metal intoxication (mercury and arsenic) in guinea pigs may cause damage to labyrinthine blood vessels by swelling of the endothelial cells, mitochondrial disintegration and sometimes protrusion of endothelial cell cytoplasm herniating into the blood vessel lumen. Chronic mercury intoxication resulted in distorted endothelial cells with an increase in the density of their cytoplasm. An altered vascular permeability is likely to occur as the result of the morphological changes.

Aniline Compounds↗