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Biomedical subjects

R A Chole

Publications and source records attributed to R A Chole.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Fine morphology of bony dysplasia of the murine ear: comparisons with otosclerosis.

Dysplastic bony lesions that bear certain similarities to otosclerosis occur spontaneously in LP/J inbred mice. These lesions develop after the fifth week of life and progressively enlarge; they are present in 90% of animals by 90 weeks of age. In the present study, the fine morphology of these lesions was investigated. Dysplastic lesions in the middle ear of LP/J mice appeared to begin as subperiosteal accumulations of amorphous material. These accumulations occurred adjacent to the bone surface below the epithelium of the middle ear. This amorphous material was often associated with macrophages on the adjacent epithelial surface. The material appeared to be replaced with collagen fibers in a disorganized manner, forming a homogeneous base (osteoid) on which calcification occurred. The fine morphology and periodicity of the collagen appeared normal. The lesions then calcified by forming calcospherites that became confluent. During this period, transformed fibroblasts (osteoblasts) appeared in the calcifying matrix, resulting in a lesion made of bone. These lesions could sometimes be seen replacing normal bony contours but most often were exophytic. The lesions at all stages of development may be associated with macrophages and effusions in the middle ear. The lesions in the middle ear of LP/J mice appeared to develop by an active process of bone formation; in contrast, otosclerosis is an active process of bone resorption and formation.

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The possible role of immunologic injury in the dysplastic bony lesion in LP/J mice.

An immunohistologic study was performed on temporal bones from 30 LP/J mice and 17 CBA/J mice to assess the role of immunologic injury in the pathogenesis of dysplastic bony lesions in LP/J mice. Temporal bones were harvested from animals aged 2 to 31 months to evaluate the progression of the disease. As early as 2 months of age, before the onset of bony lesions, the tympanic cavities frequently contained small effusions coating the ossicles and otic capsules that were demonstrated to contain immunoglobulins and pockets of macrophages. Later in the course of the disease, bony lesions grossly and histologically similar to human otosclerosis developed, which stained for immunoglobulins. No similar bony lesions, effusions, cellular infiltrates, or staining for immunoglobulins was detected in the control animals, even in the presence of acute otitis media. This study suggests a role of immunologic injury in the pathogenesis of dysplastic bony lesions in LP/J mice.

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Estimate of vitamin A in the guinea pig cochlea.

Microfluorometric estimates of the membranous structures of the freeze-dried guinea pig cochlea have demonstrated that vitamin A is present in these tissues at a concentration of 21.2 microgram/gm (SD +/- 4.77 microgram) which is approximately ten times the vitamin A concentration in most other tissues.

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Petrous apicitis. Clinical considerations.

Although petrous apicitis was a frequent occurrence in the first half of this century, it has become an uncommon disease because of the widespread use of antibiotics for otitis media. In this series of eight cases of petrous apicitis it is evident that petrositis cannot be equated with Gradenigo's triad (otitis, abducens paralysis, and deep pain) since none of the cases manifested with the classical syndrome. Abducens paralysis was seen in only two of the eight cases. Deep facial or ear pain was present in four of the eight cases and appeared to be the most useful symptom in the diagnosis of petrositis. Four of the eight cases were discovered only after previous, unsuccessful surgical procedures. Chronic petrous apicitis may be occult and manifest only after failure to control suppuration by conventional tympanomastoid surgery. When petrositis is suspected, conventional x-ray study may show bone erosion and asymmetric clouding of the petrous tip. Computed tomographic scanning was most useful in the delineation of bone destruction and of the apex. When the diagnosis of petrous apicitis is made, aggressive surgical drainage is indicated.

Adolescent↗
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Pressure-induced bone resorption in the middle ear.

Osteoclastic activity is seen in areas of bone resorption which are the result of experimental and human cholesteatoma. Many factors may induce osteoclasts, including transmitted pressure. The purpose of this study was to determine if transmitted pressure, in the absence of cholesteatoma, could cause localized bone resorption in the middle ear. Surgical grade silicone was implanted into the middle ear of gerbils without cholesteatoma. Bone resorption was observed only in areas where the implants exerted pressure on bone. It was estimated that pressures of 50 to 120 mm Hg (6.7 X 10(4) to 16 X 10(4) dynes/cm2) resulted in the induction of osteoclastic bone resorption.

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Dynamics of otosclerosis-like lesions in LP/J mice.

The LP/J inbred mouse is the first known animal to spontaneously develop otosclerosis-like bone lesions in the middle and inner ear. These abnormal bone foci resemble human otosclerotic lesions, are inherited, and produce a progressive hearing loss. On the basis of histological evaluation alone, it was unclear whether these otosclerosis-like lesions in LP/J mice develop suddenly or gradually as in human otosclerosis. To study the dynamics of lesion formation, four different colored fluorochrome bone labels were given in sequence to postpubertal LP/J mice and CBA/J mice as normal controls. All of the otosclerosis-like lesions incorporated at least one fluorochrome, and half were labeled with two or more markers indicating continuous lesion growth over many weeks. It appears that otosclerosis-like lesions in LP/J mice develop during early adulthood and progress gradually as in human otosclerosis.

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Experimental retraction pocket cholesteatoma.

An animal model for retraction pocket (primary acquired) cholesteatoma is presented. Bilateral eustachian tube obstruction by electrocauterization of the nasopharyngeal portion was performed in 16 Mongolian gerbils. Animals were killed at 2, 4, 8, and 16 weeks. At 2 weeks all animals had bilateral serous effusions and retracted tympanic membranes. At 4 weeks, four of eight ears had middle ear fluid, retractions, and cholesteatomas. After 8 weeks, five of eight ears had middle ear effusions, and four of these had cholesteatomas; one ear had total atelectasis with a cholesteatoma filling the bulla. By 16 weeks, six of eight ears had developed cholesteatomas. Some animals did not develop effusion or retraction because of failure or recanalization of eustachian tube obstruction. This study provides experimental evidence that aural cholesteatomas may arise by retraction of the tympanic membrane.

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Cochlear hair cell loss in ears with cholesteatomas. Scanning electron microscopy study.

Cochleas from 16 Mongolian gerbils with spontaneous aural cholesteatomas, and four of similar age without cholesteatomas, were examined by scanning electron microscopy to quantify cochlear hair cell loss. Loss of hair cell stereocilia was found in all ears with cholesteatomas and was significantly increased when compared with uninvolved ears from animals of similar age. The hair cell loss associated with gerbilline cholesteatomas appeared to be most marked in the middle turn of the cochlea and increased in severity with increasing size of the cholesteatomas. Outer hair cells were affected more than inner hair cells. Inner and outer hair cell loss was not significantly different in infected cholesteatomas versus sterile cholesteatomas. The greater damage to hair cells at the middle turn compared to the basal turn suggests that these losses may be the result of some agent acting through the cochlear wall rather than through the round window.

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Osteoclasts in chronic otitis media, cholesteatoma, and otosclerosis.

Bone resorption and remodeling are characteristic of chronic otitis media with and without cholesteatoma and otosclerosis. The consequences of this remodeling process may be hearing loss, repeated infection, vestibular disturbance, or intracranial complications. Evidence of osteoclastic bone resorption was found in surgical specimens of 11 of 24 cases of cholesteatoma, two of three cases of chronic otitis media, and three of ten cases of otosclerotic stapes; all three spongiotic lesions had osteoclasts. With careful serial sectioning these cells are almost always multinucleate and have the typical appearance of osteoclasts with ruffled borders. Some specimens had evidence of bone erosion in the absence of osteoclasts; this finding represents an inactive phase of the remodeling process. Since the osteoclast plays an important role in the resorption and remodeling of bone in these middle ear diseases, the source, physiology, and local control of these cells are of prime importance in investigating the pathophysiology of these diseases. At the present time, the local control of activation and recruitment of osteoclasts, as well as their chemotactic responses, is poorly understood.

Bone Resorption↗
PubMedDate not supplied

Experimental studies on the role of vitamin A in the inner ear.

With the sole exception of the hair cells of the inner ear, where information is lacking, all special somatic afferent receptor cells have been shown to be dependent upon vitamin A for normal function. In view of the paucity of information on the role of vitamin A in the inner ear, three experiments were performed to examine this relationship. Temporal bone histopathology was studied in rats deprived of vitamin A. In a second experiment, vitamin A-deficient rats were maintained with vitamin A acid and the histopathology was studied under the light microscope. In the third experiment, a microfluorometric estimate of the content of vitamin A in the guinea pig cochlea was performed. A fluorescent compound with the exact spectral characteristics of vitamin A was found in the guinea pig cochlea at a concentration of 21.2 micrograms/gm, which is ten times the vitamin A concentration found in most other tissues.

Age Factors↗
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Differential diagnosis of superficial ulcerations of the oral mucosa.

Superficial ulcerations of the oral mucosa often present a diagnostic challenge to the physician because of the similarity of one ulcer to another. A diagnosis is made by the analysis of multple factors, including the lesion's location, size, grouping, onset, patient's age, involvement of other systems of the body, and course of the disease. The histopathology of the lesion may be specific, especially in certain potentially fatal diseases. This paper presents the means for the differential diagnosis of a variety of superficial ulcers of the oral mucosa: varicella, herpangina, recurrent aphthous stomatitis, Behçet's disease, Stevens-Johnson syndrome, traumatic ulcer, verrucous carcinoma, primary herpetic gingivostomatitis, recurrent herpetic stomatitis, pemphigus vulgaris, and benign mucous membrane pemphigoid.

Adolescent↗
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Squamous metaplasia of the middle ear mucosa during vitamin A deprivation.

Adult and juvenile albino rats were maintained on a vitamin A-free test diet for 2 to 28 weeks. Histologic study of the middle ear and eustachian tube mucosa of these animals showed extensive focal squamous metaplasia when compared with the control group. Keratinization of large areas of normally columnar, ciliated epithelium was observed without frank keratoma formation. In over half of the most vitamin A-deficient animals, acute otitis media with effusion was found. It is hypothesized that vitamin A deficiency disrupts the mucocilliary clearing mechanism in the middle ear and eustachian tube, which may lead to effusion and otitis media.

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Retropharyngeal abscess in the adult.

Retropharyngeal and prevertebral abscesses, although uncommon, present a perplexing diagnostic and therapeutic problem. In the adult, the disease is less common than in the child, but its etiology may be more diverse. Four cases of retropharyngeal or prevertebral abscesses in the adult are presented, resulting from (1) endotracheal intubation trauma, (2) esophageal perforation, (3) tuberculosis of the cervical spine, and (4) coccidioidomycosis. The pathophysiologic conditions and pertinent anatomy are discussed in relation to the medical and surgical approach to these lesions.

Abscess↗
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Cochlear electrical activity in the C57BL/6 laboratory mouse: volume-conducted vertex and round window responses.

Remote (vertex-positive, volume-conducted) and local (round window, or RW) responses were simultaneously recorded from the C57BL/6 mouse. Volume-conducted responses were obtained which corresponded to the cochlear microphonic (CM), summating potential (SP), and action potential (AP), as measured at the RW. The vertex PI, corresponding to the AP, had a shorter latency to rarefaction than to condensation clicks. At higher SPL's bimodal PI peaks (a and b) were observed. PIb amplitudes were greater at lower, and PIa amplitudes were greater at higher SPL'S. Responses subsequent to the RW N1 and the volume-conducted P1 were eliminated after the ear was isolated from the brainstem.

Acoustic Stimulation↗
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Cholesteatoma. Experimental induction in the Mongolian Gerbil, Meriones Unguiculaus.

Surgical ligation of the external auditory canal of the Mongolian gerbil produces aural cholesteatomas that are similar to the spontaneous gerbilline cholesteatoma. Some 6-9 months after ligation of the external auditory canal, these cholesteatomas are in contact with the bone of the middle ear. These induced cholesteatomas were seen to erode bone and displace soft tissue structures, as is typical of human aural cholesteatomas. The induced gerbilline cholesteatoma is an ideal experimental model for the study of the osteolytic characteristics of cholesteatoma.

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Hyperthermia increases aminoglycoside ototoxicity.

Similarities were noted between the nature of inner ear damage produced by loud sounds and by aminoglycoside antibiotics. Since body temperature affects cochlear function and influences the effects of noise on the ear, a similar effect was predicted for the aminoglycoside, kanamycin. By environmentally elevating the body temperatures of preweanling mice to approximately 1 degree C above that of the normal adult, kanamycin ototoxicity was increased (an average 20.4 dB threshold elevation, vs. 9.3 dB for kanamycin injected mice reared at room temperature). Hyperthermia per se had no influence on auditory thresholds. This may be of relevance to humans with fever who are treated with aminoglycoside antibiotics.

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Cholesteatoma induction. Consequences of external auditory canal ligation in gerbils, cats, hamsters, guinea pigs, mice and rats.

Surgical ligation of the external auditory canals of Mongolian gerbils produces aural cholesteatomas that are similar to spontaneous gerbilline cholesteatomas. These experimental cholesteatomas expand rapidly, medially displacing the tympanic membrane and eroding bone. Less than 2 months after ligation, half these cholesteatomas are in contact with the bony prominence of the cochlea. Ligation-induced formation of cholesteatomas may be unique to the gerbil. Keratin deposits are produced by similar ligations of the external auditory canals of cats, guinea pigs, hamsters, mice, and rats. However, in these animals there is no medial displacement of the tympanic membrane, no cholesteatoma formation, and no bone erosion. Cholesteatomas were not seen in cats, guinea pigs, hamsters, mice, and rats even after post-ligation intervals of 6 to 36 months.

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