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Biomedical subjects

M Hawke

Publications and source records attributed to M Hawke.

At least 109 records · Page 6Linked to original sources
PubMed1986

A paradigm for tympanic epithelial dispersion.

It is more than a century since tympanic epithelial dispersion was first noted. This concept has not been analyzed mechanically until now. Serial photography of a circular disc holding 530 2.5 mm diameter ball-bearings, some of which were painted black to represent ink dots, has shown the centrifugal movement, enlargement and fragmentation of these marked areas when ball-bearings are added at random into the monolayer. Ink dots applied to mammalian drumheads move in a similar fashion. The model not only represented all the known tympanic epithelial phenomena faithfully, but could also be used to predict a mitotic index for the human drum. The index derived is consistent with normal human forearm skin if the dispersion of the corneocytes is due to the final shape change and insertion of lower epithelial cells into the lowest corneocyte layer.

Cell Movement↗
PubMed1986

Automastoidectomy caused by keratosis obturans: a case report.

This is a case report of a 25-year-old Oriental woman with persistent and neglected keratosis obturans. The enlarging plug of keratin in the deep meatus produced an "automastoidectomy" in the left ear. The clinical findings are supplemented with a preoperative CT scan, and by pre- and postoperative Hopkins rod photographs of the ear. This case demonstrates dramatically the extensive erosion of bone that can occur in a patient with neglected keratosis obturans.

Adult↗
PubMed1985

Histopathology of the temporal bone in osteogenesis imperfecta congenita: a report of 5 cases.

The histopathologic findings in 8 temporal bones from 5 patients with osteogenesis imperfecta congenita are reported. The otic capsule, bony walls of middle ear, and ossicles showed evidence of both deficient and abnormal ossification. Microfractures were found in the otic capsule and in the anterior process and handle of the malleus, in addition to their common location at the crura of the stapes. The cochlear and vestibular end-organs appeared normal. Pathologic changes compatible with otosclerosis were not seen. The possible implication of these changes on hearing and balance is discussed.

Ear, Inner↗
PubMed1985

Radiation effects on the external auditory canal.

Radiation is used to treat many head and neck tumors, and of necessity the temporal bone is sometimes included in the paths of radiation. We studied the histopathology of the external auditory canal in 13 temporal bones from 10 patients who had undergone irradiation for head and neck tumors. The pathologic changes noted could be divided into: bony changes, and soft tissue changes. Bony changes manifested were those of resorption, fibrosis, empty lacunae, and sequestration. There were five soft tissue changes: the formation of a secondary cholesteatoma, ulceration of the lining epithelium with resorption of the underlying bone, thickened epithelium in the canal as well as in the tympanic membrane, subepithelial fibrosis, and atrophic ceruminous glands. Clinically these changes can be manifested as a persistent otitis externa, with otorrhea and otalgia.

Adult↗
PubMed1985

Paget's disease and the temporal bone--a clinical and histopathological review of six temporal bones.

Paget's disease of bone occurs more commonly in the elderly and has been reported to involve the temporal bone in 30% of those afflicted. The clinical and histopathological features of six temporal bones from three patients with this disease are reported and the relevant literature reviewed. The effect of Paget's disease on the middle ear structures was more variable than its extension into the otic capsule. Pagetic involvement of the otic capsule was observed in five temporal bones. One patient had bilateral asymptomatic neurofibromas in the eighth cranial nerve. the potential mechanisms responsible for the conductive deafness, the sensorineural deafness and vestibular dysfunction associated with Paget's disease are discussed.

Age Factors↗
PubMed1985

Clinical and histological evidence for the presence of the vomeronasal (Jacobson's) organ in adult humans.

One hundred adult humans were examined specifically for the presence of the opening of the vomeronasal organ (VNO) on the antero-inferior part of the nasal septum. This was found in 39% of patients. Twenty-seven human septums were removed at post mortem, examined macroscopically, sectioned coronally and examined microscopically. In 70% of these specimens, vomeronasal structures were identified. Histological examination failed to reveal any evidence that these organs may be functional. The human embryology and comparative anatomy of the VNO are reviewed. The physiological function in different vertebrates is also considered, and the significance of the findings in this study is assessed in the light of this evidence.

Adolescent↗
PubMed1985

Cell shape in the migratory epidermis of the external auditory canal.

The shapes adopted by cells migrating within tissues and in cell cultures are related to both the direction and mechanism of migration. The skin on the tympanic membrane and deep external auditory canal is unique in its ability to migrate from the tympanic membrane to the junction between the deep and superficial parts of the ear canal, where it desquamates. Observations on 24 surface preparations of skin, obtained from 17 human temporal bones, revealed that the basal cells of the epidermis were spindle-shaped, and their long axes were aligned in the direction of migration. This cellular asymmetry and orientation did not persist in the more superficial layers of the epidermis. These findings are important in the consideration of the mechanism of migration, and the level within the epidermis at which it occurs.

Adult↗
PubMed1985

An ultrastructural study of the skin of the tympanic membrane and external ear canal of the guinea pig.

The ultrastructure of the skin covering the tympanic membrane and external ear canal has been studied in eight guinea pigs, to identify any features which could be related to the rapid movement of the epidermal surface at this site. Migratory epidermis showed evidence of reduced intercellular adhesion in the deeper layers and reduced differentiation in all layers. Differentiation was more evident in cell ridges found at the junctional zone between migratory and non-migratory skin. The findings agree with those of previous authors, and indicate that migration is most likely to occur within the deeper layers of the epidermis.

Animals↗
PubMed1984

Thickness of the migratory epithelium of the external auditory canal.

The migratory epithelium of the external ear has been the object of much study, and it has long been presumed to thicken in abnormal conditions of the external ear. In this study, normal values have been established for the thickness of the epithelium at various sites on horizontally sectioned normal temporal bones. Three sites, the umbo, the anterior annulus, and the posterior annulus are shown to have statistically significant thickening when compared with other contiguous sites on the same section. A study of temporal bones with various abnormalities of both external and middle ear showed a statistically significant thickening of the epithelium when compared with the normal bones. This difference was particularly marked at the umbo, anterior annulus, and posterior annulus. This would imply that these thickened areas may represent growth centers in the epithelium of the external ear.

Aged↗
PubMed1984

The pathologic features of keratosis obturans and cholesteatoma of the external auditory canal.

The presence of a keratin plug occluding the deep external auditory canal was first noted and documented in the 19th century. It has subsequently been proposed that two different diseases can be responsible for the presence of this type of obstruction within the deep meatus: keratosis obturans and external auditory canal cholesteatoma. Keratosis obturans is characterized by a dense plug of keratin debris located primarily within the deep meatus. There is an associated hyperplasia of the underlying epithelium and evidence of chronic inflammation within the subepithelial tissue. There is no evidence of erosion or necrosis of the underlying bone. In external auditory canal cholesteatoma the significant finding is extensive erosion of the bony external auditory canal by a wide-mouthed sac, lined with stratified squamous keratinizing epithelium, that arises lateral to the tympanic membrane and is located in the inferior portion of the bony external canal. There is frequently evidence of sequestration of the underlying bone.

Aged↗
PubMed1984

1984 Hodge memorial Award--surface wrinkles, cell ridges, and desquamation in the external auditory canal.

The phenomenon of epithelial migration from the tympanic membrane laterally along the external auditory meatus has long been recognized, and the site of keratin desquamation observed. In this study, the surface features of deep canal epithelium have been studied in 14 human temporal bones, and skin removed from 21 human temporal bones has been sectioned and studied by light microscopy. The findings reveal the role of hairs and ceruminous glands in the desquamation of deep canal stratum corneum, and elucidate the migratory mechanism. The formation an distribution of keratin wrinkles and cellular ridges in the external canal are explained.

Adult↗
PubMed1984

Mast cells in human middle ear mucosa in health and in disease.

The distribution of mast cells was studied in normal human middle ear mucoperiosteal lining and in middle ear biopsies of patients with acute and chronic otitis media. The mast cells were identified on the basis of the metachromatic staining for their cytoplasmic granules with Giemsa and toluidine blue. Only a few mast cells located in proximity to blood vessels in the lamina propria underneath the epithelial layer were observed in normal middle ear mucoperiosteum. The number of mast cells in acute inflammatory reactions and in the normal middle ear lining was similar. By contrast, the mast cell count was significantly increased in chronic inflammatory reactions. The population density of the mast cells was the highest in the subepithelial layer of cholesteatoma, in regions where the lamina propria showed fibrosis and infiltration with chronic inflammatory cells, and around mucous glands. The presence of increased numbers of mast cells in chronic otitis media is consistent with our previous finding of high levels of histamine in middle ear effusions. It is postulated that mast cells play an important role in the pathogenesis of chronic otitis media through the release of their active biochemical mediators.

Adolescent↗
PubMed1984

The role of histamine in secretory otitis media.

Secretory otitis media is the most common cause of hearing loss in children. Although allergy has been suggested as a possible cause, its role as an etiologic factor in the formation of secretory otitis media is controversial. The presence of histamine in most middle ear effusions is thought to be generated from inflammatory and not allergic provocation. This potent mediator of inflammation may contribute to the chronicity of secretory otitis media.

Adolescent↗
PubMed1984

Clinical and microbiological features of otitis externa.

A prospective study of 40 cases of acute otitis externa and 99 cases of chronic otitis externa in unselected patients revealed that otitis externa affects males and females with a similar frequency. The peak incidence occurs in the summer and early fall months of the year. Exposure to water, previous use of ear drops, and cotton-tipped applicators predisposed to both acute and chronic otitis externa. Hearing aid ear molds appear to be a predisposing factor in the development of chronic otitis externa. Pain, itching, discharge, and hearing loss were the most common presenting complaints in both acute and chronic otitis externa. The discharge in chronic otitis externa is more commonly purulent, whereas in acute otitis externa it is more commonly mucoid. The tympanic membrane is not frequently involved in acute otitis externa; however, in chronic otitis externa changes in the tympanic membrane were more often encountered. Most infections were of a pure bacterial origin, primarily Pseudomonas aeruginosa and Staphylococcus aureus. Fungi were the causative organisms more commonly in chronic otitis externa than in acute otitis externa (Figure 7). It was found that previous usage of ear drops was more often associated with otomycosis in acute otitis externa and yet was not related to a higher frequency of otomycosis in chronic otitis externa. The presence of a foreign material, such as an ear mold, was associated with a greater frequency of mixed infections (bacteria and fungi) in the group with chronic otitis externa. The presence of a greenish discharge or foul odor was not related to any particular organism.

Adolescent↗