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Biomedical subjects

D J Lim

Publications and source records attributed to D J Lim.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Histochemical localization of carbonic anhydrase in the inner ear.

Carbonic anhydrase was histochemically located in chinchilla inner ear tissues. A strong carbonic anhydrase reaction was observed in the spiral ligament cells, Boettcher's cells, the external sulcus cells, and the stria vascularis (intermediate and/or basal cells). The enzymatic reaction was also positive in the supporting cells of all vestibular sensory epithelia, as well as in the dark cells and transitional cells of the utricle and saccule. Some epithelial cells of the endolymphatic sac were also positive. It is speculated that this enzyme may be involved in: 1) ionic or fluid regulation of the endolymph, 2) removal of CO2 from the inner ear tissue near the sensory cells, and 3) otoconia formation and maintenance.

Animals↗
PubMedDate not supplied

A morphometric study of the pallid mutant mouse inner ear.

Mice homozygous for the mutant gene pallid (pa/pa) often lack otoconia in some or all of their maculae and are used to study the influences of gravity receptor hypostimulation on vestibular-related behaviors. Since the value of this animal model is based on the assumption that the vestibular sensorineural elements are normal, a morphometric analysis was done on the inner ear of these otoconia-deficient mice to see whether sensori-neural structures are also affected by the pallid gene. In pallid mice lacking all otoconia, the sensory epithelia of the utricle, saccule, and semicircular canal cristae were the same size as in their heterozygous (pa/+) controls. Although the superior and inferior divisions of the vestibular ganglion of the pallid mice were smaller than normal, the first-order neurons within these divisions were normal in size, number, and density. However, the superior divisions in both groups had larger neurons than did the inferior divisions. Within the pallid cochlea, first-order auditory neurons within the spiral ganglion were smaller than normal, but the scala media was larger. Since the significant vestibular influences of the pallid gene are limited primarily to the otoconia, behavioral abnormalities reported for these otoconia-deficient mice are apparently due only to gravity receptor hypostimulation.

Animals↗
PubMedDate not supplied

Experimental otitis media with effusion induced by nonviable Hemophilus influenzae: cytologic and histologic study.

In an earlier study the authors demonstrated that formalin-killed Hemophilus influenzae induces serous-type middle ear effusion in chinchillas and provides an excellent model for the study of human otitis media with effusion. The present study was initiated to evaluate the morphologic and histologic changes that occur in the middle ear after injection of this organism. All of the experimental animals injected with formalin-killed H. influenzae in the present study had straw-colored serous-type effusions within four days after injection. The submucosal thickness, mononuclear cell density, and capillary permeability all increased dramatically in the experimental animals. Marked bleeding, tissue edema, and cellular infiltration in the submucosa were prominent findings after injection of the inactivated bacteria. Half of the experimental animals had histologic evidence of marked proliferation of epithelial cells resembling adhesive otitis media. These findings suggest that nonviable H. influenzae are capable of inducing severe inflammatory changes in the middle ear and may play an important role in the pathogenesis of otitis media with effusion and its sequelae.

Animals↗
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Dissociated single cells from the inner ear: strial cells.

Using the enzyme dissociation technique, the authors successfully isolated strial marginal cells and intermediate cells from guinea pig and chinchilla cochleas. Dissociated cells were maintained for in vitro observation under the light microscope for up to 2 hours without gross evidence of cell damage. Such single cells were successfully prepared for scanning or transmission electron microscopic observation, which showed excellent cell shape and preservation of cell organelles. However, there was evidence of increased vesiculation in the dissociated marginal cells, which is interpreted to be evidence of increased pinocytotic activity.

Animals↗
PubMedDate not supplied

Normal distribution of lysozyme- and lactoferrin-secreting cells in the chinchilla tubotympanum.

The distribution of the antibacterial enzyme lysozyme- and lactoferrin-secreting cells in the tubotympanum of normal chinchillas was studied using an immunohistochemical technique. The middle ear mucosa contained lysozyme-secreting cells and lactoferrin-secreting cells. The former were localized primarily in the columnar epithelium area and the latter primarily in the cuboidal epithelium area (that contains serous cells) of the transitional zone. In the eustachian tube, the lysozyme was localized in goblet cells of the mucosal epithelium and mucous cells of the glands, while lactoferrin was localized in serous cells of the glands. Our results indicate that secretory lysozyme and lactoferrin are secreted by different cell types (mucous or serous), supporting the notion of heterogeneity of the secretory cells of the tubotympanum. This finding is consistent with the concept that antibacterial enzyme secretion is an integral part of the normal mucosal defense system in the tubotympanum.

Animals↗
PubMedDate not supplied

Effects of noise and ototoxic drugs at the cellular level in the cochlea: a review.

Currently available information concerning the cellular mechanisms involved in acoustic trauma and aminoglycoside ototoxicity is reviewed to shed some new light on the cellular events that may be related to functional impairment of the auditory organ. Based on the available data, the following postulations can be made concerning the cellular mechanisms involved. 1) The macromolecular disruption of the stereocilia and cuticular plates is the initial cellular event in acoustic trauma. This disruption would affect the micromechanics of the transduction process, leading to temporary threshold shift. Further cellular impairment would involve basic cellular functions such as the protein, lipid, and glucose synthesis needed for cell repair and survival, and such impairment would result in permanent cell injury or cell death, leading to permanent threshold shift. 2) It can be postulated that the cellular mechanisms involved in aminoglycoside ototoxicity include two events. The early event is the reversible blockage of the transduction channels from the endolymph side of the hair cells. The later event is the interference in such cellular functions as protein and/or phospholipid synthesis because of binding of aminoglycoside to the phospholipids and/or protein, leading to cell death. The latter event may be facilitated by penetration or membrane-mediated internalization of the aminoglycoside from the perilymph side of the hair cell.

Aminoglycosides↗
PubMedDate not supplied

Anatomy of the chinchilla bulla and eustachian tube: I. Gross and microscopic study.

The middle ear mucosa and eustachian tube of the normal chinchilla were studied quantitatively and under light microscopy to determine the distribution of each cell type of the lining epithelium and subepithelial gland. The middle ear mucosa consisted of columnar epithelium, cuboidal epithelium, and squamous epithelium. The lining epithelium of the eustachian tube was ciliated pseudostratified columnar epithelium. These epithelia were composed of ciliated, secretory, nonciliated (nonsecretory), and basal cells. The density of the ciliated cells was highest in the columnar epithelium area of the transitional zone of the middle ear mucosa. However, the density of the secretory cells was highest in the pharyngeal orifice of the eustachian tube. The nonciliated cell density was highest in the squamous epithelium area of the middle ear mucosa and decreased progressively toward the tympanic orifice of the eustachian tube. In the eustachian tube, the nonciliated cell density was highest in the pharyngeal portion of the eustachian tube, especially in the upper portion of the lateral wall. The subepithelial glands were tubuloacinar mixed glands composed of serous demilunes and mucous acini. The glands were localized primarily in the pharyngeal orifice and pharyngeal portion of the eustachian tube, and their ductal openings were present primarily in the inferior portion of the eustachian tube.

Animals↗
PubMedDate not supplied

Morphologic and immunohistochemical observation of otosclerotic stapes: a preliminary study.

Stapes with otosclerotic lesions obtained during stapedectomies were examined with light microscopy, histochemistry, immunochemistry, and electron microscopy to elucidate the cellular mechanism(s) involved in this disease process. Three types of lesions were identified: cellular (spongiotic), fibrotic, and sclerotic. The cellular type is characterized by monocyte, macrophage, osteoblast, and osteoclast recruitment and their activation. Macrophage recruitment is an early event of otosclerosis. The fibrotic type is characterized by extensive fibrosis of the bone, and the sclerotic type is characterized by a paucity of bone cells. Cytochemical results showed a large accumulation of granular substances positive for periodic acid-Schiff stain along the edge of the marrow spaces coinciding with ultrastructural calcospherite deposits, suggesting that glycosaminoglycans are involved in the mineralization process. Acid phosphatase is largely localized in the osteoclasts, but a sporadic diffusion of this enzyme was observed in the demineralizing front of the preotosclerotic lesion. Immunoglobulin G and complement C3 were colocalized in pericapillary tissue, suggesting deposit of immune complex in the spongiotic lesion. This finding indicates a possibility that immune mechanisms are involved in otosclerosis.

Acid Phosphatase↗
PubMedDate not supplied

The effect of antecedent influenza A virus infection on the adherence of Hemophilus influenzae to chinchilla tracheal epithelium.

The adherence of Hemophilus influenzae (type b and nontypable) to ciliated chinchilla respiratory epithelium was investigated using a whole organ perfusion technique. Nontypable H influenzae (NTHi) were shown to be more adherent than type b to these organized and differentiated tracheal organ cultures. Bacteria were found adhering to ciliated cells. Antecedent influenza A virus infection had no effect on adherence of NTHi for at least 48 hours. However, 72 hours after exposure to the virus, infected tissues demonstrated significantly fewer adherent bacteria than did controls. To summarize, influenza A virus infection was not found to augment the initiation of NTHi adherence to ciliated respiratory epithelium in this model.

Animals↗
PubMedDate not supplied

Secretory lysozyme of the human middle ear mucosa: immunocytochemical localization.

Lysozyme was demonstrated by an immunocytochemical technique in the biopsied mucosa obtained from the promontory of the fifteen patients who had chronic middle ear effusions. Lysozyme was localized in the mucigen granules of the secretory cells, as well as in the specific granules of the polymorphonuclear neutrophilic leukobytes (PMN) and macrophages. The specimens obtained from patients with mucous effusion showed numerous secretory cells that contained lysozyme, in sharp contrast to the serous type in which only a few secretory cells could be found. The present morphological finding was in agreement with the biochemical finding which demonstrated higher lysozyme level in mucous effusions than that of the serous type. It was concluded that human middle ear mucosa provided lysozyme and that its secretion was active in serous otitis media, particularly of mucoid type.

Child↗
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Ultrastructural cochlear changes following acoustic hyperstimulation and ototoxicity.

Using guinea pigs and chinchillas as experimental animals, modes and patterns of sensory cell damage by acoustic hyperstimulation and kanamycin intoxication were compared. In general, outer hair cells were more vulnerable to both acoustic trauma and ototoxicity (particularly in the basal turn) than inner hair cells. However, in kanamycin ototoxicity, the inner hair cells were more vulnerable in the apical coil. Nerve endings and nerve fibers generally were resistant to both acoustic trauma and kanamycin intoxication, and their degeneration appears to be secondary to the sensory cell degeneration. A large number of unmyelinated nerve fibers were seen in both the organ of Corti and the osseous spiral lamina even three months after the organ of Corti had been completely degenerated by ototoxicity. The total number of unmyelinated and myelinated nerve fibers in the osseous spiral lamina far exceeded the scanty surviving ganglion cells in Rosenthal's canal, indicating the possibility of regeneration of these fibers following kanamycin intoxication. The remaining few ganglion cells were mainly type II or type III cells, and a majority of the type I ganglion cells appeared to be degenerated. Signs of strial damage were observed in both acoustic trauma and ototoxicity, but their pattern did not correlate well with that of sensory cell degeneration.

Animals↗
PubMedDate not supplied

Functional morphology of the mucosa of the middle ear and Eustachian tube.

A review of available histological, histochemical and ultrastructural data on middle ear mucosa and the Eustachian tube was made to provide a broad cellular basis for understanding middle ear effusions. The presence of mucociliary defense system in a large part of the Eustachian tube and middle ear is seen as the first line of defense. Secretion by the mucosa has a profound biological significance. Immunoglobulins A, G, and even E and M are produced locally by the mucosa and may contribute to the immunodefense of the middle ear. Secretory lysozyme is also produced by the mucosa and may contribute enzymatic defense of the ear. Mucosal immunoglobulins and lysozyme are significantly elevated in the effusions, which would imply that local defense systems are hyperactive in OME. It also appears that these increases are related to the increase of the secretory cell population. It is also suspected that auditory surface-active agent is produced locally and may facilitate normal function of the tube. The middle ear also can transport macromolecules very rapidly across intact mucosal epithelium. The large numbers of tissue and wandering macrophages found in the mucosa and effusions would also imply that the middle ear is capable of efficient phagocytosis, which may be involved in processing antigen.

Animals↗
PubMedDate not supplied

Immunoglobulin E in chronic middle ear effusions.

A total of 61 middle ear effusions and matched sera obtained from patients suffering from chronic otitis media with effusions (OME) was examined for IgE and other immunoglobulins to see if a reaginic antibody is involved in OME. The IgE levels were determined by the Phadebas IgE radioimmunoassay test. Excluding one patient who had extremely high IgE as a result of parasitosis, there were only three cases which showed marginally increased serum IgE levels. Elevated IgE levels in sera and/or in effusions were unrelated to a history of allergy. The mucoid effusions had significantly higher effusion levels than the levels in corresponding sera (p less than .0005). Fourteen percent of the cases examined showed effusion IgE levels five times or more higher than serum levels. Biopsy specimens of these patients showed numerous degranulating mast cells. Only two specimens showed eosinophilic infiltration. It is suggested that the IgE is produced locally by the mucosa in mucoid-type effusions and may have been involved in mast cell degranulation. However, this study cannot confirm the allergic nature of the OME.

Adolescent↗
PubMedDate not supplied

Antimicrobial factors and bacterial correlation in chronic otitis media with effusion.

Analyses of effusions and sera from patients with otitis media with effusion demonstrated local production in the middle ear of lysozyme, IgA and IgG. The effusion IgM was markedly elevated in some patients, also indicating local production. Complement C3 with rare exception was significantly lower in effusions than sera, suggesting utilization of complement in the middle ear, perhaps in conjunction with antibodies. The presence of high levels of lysozyme and immunoglobulins in effusions correlates with the low isolation rate of microorganisms in culture and may influence survival of organisms in the middle ear.

Child↗