Biomedical subjects
Publications and source records attributed to M Hawke.
An area of nonlamellar new bone formation was observed in the anterior epitympanic region of 27 randomly chosen human temporal bones. The donors ranged in age from 9 to 80 years and had no evidence of ear disease or systemic skeletal or metabolic abnormalities. The frequency of this finding suggests that it is a normal feather of the human anterior attic recess.
Postmoretem examination of undecaicified temporal bones from five patients treated with tetracycline during adult life for unrelated disease showed the uptake of tetracycline label within the endochondral bone the otic capsule. Adult endochondral bone is histologically woven (nonlamellar) in character, and has been assumed to be metabolically inert in the healthy state. The strong perlvascular labelling seen suggests that new bone is normally deposited in the otic capsule and that this new bone is lamellar in character. Continuous new bone formation in the presence of a constant net volume of bone implies that resorption must also occur normally within the otic capsule.
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The right heart and great veins can be the harbinger of septic and aseptic thromboemboli, which can result in a spectrum of clinical syndromes. This report presents five distinct clinical scenarios of thromboembolization, the occurrence of which in the central circulation resulted in life-threatening sepsis and hemodynamic and pulmonary insufficiency. Recommendations for therapeutic intervention and a review of the literature also are presented.
The presence of histamine in 131 middle ear effusions was determined by the fluorometric assay technique. This potent mediator of inflammation was found in significant amounts in most of the samples, suggesting that it may play an important role in the pathogenesis of otitis media with effusion. It is postulated that mast cells located in the lamina propria of the tympanic mucoperiosteum are triggered to degranulate and release histamine by anaphylatoxin derived from activation of the complement system.
Twenty-two surgical specimens of eroded middle ear ossicles were removed from patients with chronic otitis media, with and without cholesteatoma. By using specific mast cell stains, increased numbers of mast cells were found in connective or granulation tissue adjacent to eroded surface of the bone. Mast cells possess the biological machinery necessary for enhancing bone resorption, and the population density of mast cells is increased in a variety of disorders that are associated with bone resorption. It is hypothesized that mast cells contribute to bone resorption in chronic otitis media, and the possible mechanisms by which mast cells exert their action are discussed.
Casts and crusts of the tympanic membrane were removed from patients with previous otitis media. Casts are formed of adherent keratinocytes in a matrix of dried exudate. Detachment from the drumhead leaves the underlying epidermis intact. Casts are defined as those crusts that have detached spontaneously from the surface of the drum. A mechanism based on epithelial proliferation induced by inflammation within the middle ear, with subsequent keratinocyte retention and thickening, is proposed.
If the tympanic membrane or attic skin is wounded with a fine needle dipped in ink, ink particles are introduced into the epidermis and underlying tissue. These particles are subsequently taken up by cells in the epidermis and dermis. In this experiment the distribution of ink within the skin of ear canal was studied in nineteen guinea-pigs, one to ten days after wounding. Examination of the intact canal reveals that ink becomes distributed along a precise line from the wound to the point of desquamation. On sectioned tissue, the ink in this line is found to be mainly intracellular, initially in the epidermis, and subsequently in the upper dermis. When considered with other evidence, these results indicate that migration probably occurs in the deeper layers of the epidermis, and that it stops at the junction of the deep and superficial parts of the ear canal.
Although cell migration is an important function of the epithelial cells of the tympanic membrane (TM), little is known about the distribution of the F-actin cytoskeleton, a contractile protein important in cell motility. The purpose of this experiment was to study the in situ localization of F-actin in the epithelial cells of the TM. F-actin, localized using Rhodamine-phalloidin, was present as a thin cortical band at the margin of both the mucosal cells on the inner side of the drum, and the suprabasal cells of the epidermis. The basal cells showed diffuse circumferential F-actin staining sometimes appearing as short microfilaments. Following a full thickness injury, changes in the distribution of F-actin could be observed with in situ localization. While the diffuse F-actin staining of the basal cells was reduced, both long F-actin microfilament bundles extending parallel to the long axis of the cell and focal aggregates of F-actin were prominent. The suprabasal cells became elongated, and while the F-actin remained localized to the cell margin, faint central F-actin microfilaments were observed. The staining of the mucosal cells remained unchanged. This study showed that the guinea pig TM is a useful model to study the distribution of epithelial F-actin in situ under normal and repair conditions, and that the basal cell layer may be important in regulating migration in the epidermis.
During observations on healing traumatic perforations in guinea-pig tympanic membranes, a specific appearance was seen on the surface of the epidermis as it closed the perforations. In this experiment, this pattern was identified on 15 tympanic membranes in 10 guinea pigs, and serial photography was used to record the healing process in 6 perforations over 5 days. This study shows that epidermis accumulates at the inferior margin of the perforation (the side from which it migrates) and then closes over the defect. Epidermal migration appears to be a key factor in this healing process.