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Biomedical subjects

L Michaels

Publications and source records attributed to L Michaels.

At least 91 records · Page 5Linked to original sources
PubMed1989

Congenital cholesteatomas of the middle ear in children: origin and management.

Cholesteatomas (epidermoids) of the middle ear appearing medial to a normal tympanic membrane are identified in increasing numbers of young children. The evidence that these lesions are congenital in origin includes the young mean age of presentation, the normal appearance of the middle ear mucosa in almost all cases of small lesions, normal mastoid pneumatization documented by computerized tomography, the relatively large number of children with associated minor or major congenital malformations, and the consistent 3:1 ratio of males to females with the disorder in all of the large series reviewed. A direct relationship between congenital cholesteatomas (epidermoids) of the middle ear and the epidermoid formation is supported by the position of the epidermoid formation at a histologic transition zone in the anterior superior lateral quadrant of the tympanic cavity, which is also the site of greatest occurrence of congenital cholesteatomas. The epidermoid formation may not always involute and as it expands it would be expected to become visible medial to the tympanic membrane in the anterior superior quadrant. It seems evident that as the congenital cholesteatoma expands it can block the eustachian tube; during a bout of otitis media the tympanic membrane could perforate and the cholesteatoma could become secondarily infected. The congenital cholesteatoma in this situation would be difficult or impossible to distinguish from the more common acquired type.

Child, Preschool↗
PubMed1989

Osteoma of the incus.

Osteomas of the temporal bone are rare. Osteomas of the middle ear have been reported but none involving an ossicle. We describe a case of a 28-year-old man who had a conductive hearing loss caused by an osteoma of the incus.

Adult↗
PubMed1988

Origin of congenital cholesteatoma from a normally occurring epidermoid rest in the developing middle ear.

The sites of involvement of congenital cholesteatoma, a lesion which has recently become more frequently recognized, are reviewed from literature sources. There is a propensity for its occurrence, especially when small, in the anterior superior part of the middle ear. The same situation is the precise location of an epidermoid cell rest, the epidermoid formation (EF). This is seen in most fetal ears at the junction of the Eustachian tube with the middle ear near the anterior limb of the tympanic ring, until 33 weeks gestation, when it disappears. Its origin is traced to early fetal life from the ectoderm of the first branchial groove. In embryonic and early in fetal life it seems to act as an organizer in the development of the tympanic membrane and middle ear. It is likely that congenital cholesteatoma is derived from the EF by its continued growth instead of regression. Congenital cholesteatomas show a thinner and flatter matrix than acquired cholesteatomas, probably because the former are most frequently 'closed' and therefore subject to pressure effects from the keratin within the cyst. 'Open' forms also occur in smaller numbers. It is possible that a screening program for congenital cholesteatoma in infants might reduce the incidence of the severe, extended form of the disease.

Cholesteatoma↗
PubMed1988

Congenital cholesteatomas in children: an embryologic correlation.

The clinical findings in 37 children with congenital cholesteatoma of the middle ear, 17 of which have not been previously reported, are presented. Clinical findings and surgical observations are correlated with recent developmental studies. It is hypothesized that congenital cholesteatoma may originate from an epidermoid formation, which has been identified in the anterior superior lateral tympanic cavity adjacent to the anterior annulus during fetal development, and which normally is present early in development, involuting by 33 weeks' gestation. It is proposed that the epidermoid formation may not always involute, and could serve as an embryologic anlage of congenital cholesteatomas.

Adolescent↗
PubMed1988

Evolution of the epidermoid formation and its role in the development of the middle ear and tympanic membrane during the first trimester.

In a study of 20 ears from embryos and early fetuses, 16 contained structures recognizable as precursors of the epidermoid formation (EF). The earliest were small, but later they took the form of a long epithelial bud which emanated from the tip of the tubotympanic recess or Eustachian tube. At a later stage still the EF protruded into the lumen of the Eustachian tube. The early formation of the tympanic membrane, the middle ear cavity and the osseous tympanic ring all take place in the vicinity of the EF precursor. It is possible that the EF precursor may act as an organizer, playing a prominent part in the migration of the first pharyngeal pouch towards the first branchial groove and the development of the middle ear and tympanic membrane.

Ear, Middle↗
PubMed1988

The specific locomotive activity of tympanic membrane and cholesteatoma epithelium in tissue culture.

Human tympanic membrane and cholesteatomatous epithelium were grown in tissue culture. Outgrowth from the explants and colonies produced by subculture produced epithelium capable of rapid "en masse" migration. This phenomenon was not found in epithelium grown from other sites. There is a close correlation between the culture characteristics of tympanic membrane and cholesteatoma epithelium and the in vivo activities of these epithelia.

Adult↗
PubMed1987

Pathological changes in the organ of Corti in presbyacusis as revealed by microslicing and staining.

A new technique of examining the organ of Corti in the perfused human cochlea is described. The fixed cochlea is microsliced and surface preparations are prepared and then stained for light microscopy. A method of assessing the distance/length ratio of samples is also described. Counts of inner and outer hair cells in such stained surface preparations were performed on elderly subjects and compared with those of infants. A marked loss of outer and a mild loss of inner hair cells was present in the elderly subjects. Complete atrophy of variable lengths of the terminal basal coil cells was also found in all elderly cochleas. Giant stereociliary degeneration takes place in hair cells (except basal coil outer hair cells) before they disappear.

Aged↗
PubMed1987

Nasopharyngeal angiofibroma treated in 1841 by maxillectomy.

One of the earliest recorded maxillectomy procedures was carried out on a 21-year-old male in University College Hospital, London, in 1841 by Mr. Liston. The case report and operative procedure are given. The gross, radiographic and microscopic features of the resection specimen, which was preserved until the present as a museum specimen, are provided. The tumor is an advanced nasopharyngeal angiofibroma and demonstrates the mode of spread of this lesion when treatment is delayed.

Histiocytoma, Benign Fibrous↗
PubMed1987

Vocal cord paralysis and tumour length in staging postcricoid cancer.

The present UICC classification of postcricoid cancer is based on directions of tumour spread which are uncommon and difficult to assess clinically. The classification takes no note of spread into the cervical oesophagus and fails to correlate staging with survival. The aim of this study was to assess the value of other criteria, including vocal cord paralysis and tumour length, in staging 157 patients with postcricoid cancer. Both vocal cord paralysis and tumour length could be assessed in most patients, and correlated with the mode of treatment. Generalized Linear Interactive Modelling (GLIM) identified vocal cord paralysis (P less than 0.001), performance status (P less than 0.025) and the interaction of length and histological grade (P less than 0.05) as significant predictors of survival. None of these variables is included in the current UICC classification.

Actuarial Analysis↗
PubMed1986

Malignant mixed tumour. A salivary gland tumour showing both carcinomatous and sarcomatous features.

Two malignant mixed tumours, in which both carcinomatous and sarcomatous features were present, are described. They arose in the palate in patients who had undergone surgery and irradiation for a pleomorphic adenoma at the same site 30 and 36 years previously. The histological differential diagnoses of recurrent benign pleomorphic adenoma, pleomorphic adenoma resembling mesenchymal tumour, and carcinoma in (ex) pleomorphic adenoma are discussed. On the basis of their positive reaction for keratin with specific monoclonal antibodies it is suggested that the myoepithelial cells are of epithelial origin. Immunohistochemical studies together with the histological appearance of the neoplasms indicate that the carcinomatous as well as the sarcomatous elements were derived from modified myoepithelial tumour cells. Irradiation may have been responsible for inducing a true malignant mixed tumour as distinct from the more common malignancy which may arise in pleomorphic adenoma, this being a simple carcinoma.

Adenoma, Pleomorphic↗
PubMed1986

Video time-lapse microscopy of human laryngeal carcinomas in vitro.

Twelve human laryngeal carcinomas and 14 normal vocal cord epithelia were studied in vitro by the method of tissue culture incorporating video time-lapse microscopy. Different events were photographed by taking 'stills' from the television monitor during play-back. Outgrowths from both tumour and normal explants formed only as monolayers. Mitoses were mainly found to be localized approximately mid-way between explant and the edge of the outgrowth. Some cells were seen to become suddenly active producing oscillating blebs and sometimes they detached themselves from the monolayer culture and changed appearance. This was more prevalent in the tumour cultures. In both tumour and normal cell cultures lymphocytes were observed and their normal chemokinetic movement was changed into a rapid chemotactic attraction by the presence of a mitotic epithelial cell. These lymphocytes appear to represent T-suppressor cells. The present study has shown that primary tissue culture can be a valuable tool in the study of laryngeal carcinoma. The interaction between mitotic tumour cells and lymphocytes may represent a transformation of T-lymphocytes into LAK cells.

Carcinoma↗
PubMed1986

Inner hair cell loss and intracochlear clot in the preterm infant.

Little is known about the pathological changes in the cochlea of preterm infants which might be responsible for the hearing loss which the infants are at risk of developing. This study looks at the cochleas of 5 preterm infants who died at ages up to 2 weeks using light and electronmicroscopic techniques, and shows changes in the inner hair cell population in association with intracochlear clot which may be responsible for subsequent hearing loss.

Cerebral Hemorrhage↗
PubMed1986

An investigation of the squamous cell epithelium of the human larynx by the method of tissue culture.

Laryngeal squamous cell epithelium has been grown by the method of tissue culture. Explant outgrowths were examined initially. Subsequently colonies of epithelium were grown from single cells upon a feeder layer of irradiated 3T3 mouse fibroblasts in a suitable growth medium. Human prepuce, which is widely used in skin culture studies, served as a control. There were colonial differences between colonies of the squamous epithelium of the larynx which presented a loose lattice structure and those of the prepuce control which gave rise to compacted growth. However, no obvious differences were noted between squamous epithelial colonies derived from fetal and adult vocal cords epithelium.

Adult↗
PubMed1986

An epidermoid formation in the developing middle ear: possible source of cholesteatoma.

Thirty-seven of 68 middle ears from fetuses between 10 and 33 weeks gestation show an epidermoid formation (EF) on histological study. This is always found in exactly the same anatomical location: in the anterosuperior middle ear mucosa near the origin of the tympanic membrane and adjacent to the posterior edge of the anterior limb of the bony tympanic ring. The EF is not found after the 33rd week. It is likely that the EF is a vestigial relic of the epibranchial organ that is present in some vertebrates. Epidermoid tissue of primary and even some secondary cholesteatomas may have an origin in the EF.

Cholesteatoma↗
PubMed1986

Evidence for hair cell degeneration as the primary lesion in hearing loss of the elderly.

All patients in a geriatric unit showed a hearing loss with a mean value of approximately 60 dB HL. Auditory brain stem evoked responses had normal amplitudes but, in most cases, waves I and II were absent. Extratympanic electrocochleograms produced well-marked action potentials with evidence of a type of recruitment. These results suggest a primary disturbance of cochlear function peripheral to the cochlear nerve. Examination of stained surface preparations of the organ of Corti showed complete atrophy of all hair cells at the end of the basal coil and severe outer hair cell loss in all three coils. This was accompanied by a severe alteration - giant stereociliary degeneration - in some surviving cells in all cases, but no other consistent alterations in the cochlea. These findings point towards degenerative change in the hair cells as the basis for hearing loss in the elderly.

Aged↗
PubMed1985

Feasibility of subtotal laryngectomy based on whole-organ examination.

Subtotal (near-total) laryngectomy has recently been advocated to eradicate large laryngeal tumors. The operation, which preserves the cricoarytenoid joint and adjacent vocal fold, is based on the premise that many T3 and T4 tumors can be resected without complete sacrifice of the phonatory mechanism. The purpose of this study was to verify or disprove the assumption by examining sections of whole-organ laryngeal specimens. Twenty-four of the 64 specimens analyzed were determined to be resectable by subtotal laryngectomy. Twenty-two other specimens could have been resected by a more conventional conservation technique such as hemilaryngectomy or supraglottic laryngectomy. This study supports the concept of subtotal laryngectomy for selected large tumors. Guidelines for determining the suitability of the technique are suggested.

Epiglottis↗
PubMed1985

Inverted papilloma. Considerations in treatment.

Inverted papilloma is notorious for recurrence and occasional association with malignancy, leading most authors to recommend lateral rhinotomy as the initial surgical approach in all cases; however, conservative surgery has been reported effective in selected cases. To assess the role of conservative procedures, 90 cases of inverted papilloma were retrospectively reviewed. Associated malignancy was rare. Conservative surgery was successful in controlling some cases, but often required two or three operations. All patients with clear sinus films were cured by a single procedure. Abnormal mitotic activity was seen in some aggressive lesions and some associated with malignancy. The surgical exposure in inverted papilloma should be adequate to ensure complete excision. Selected patients with localized disease can be satisfactorily managed by conservative procedures if they are carefully followed. All tissue should be inspected for possible malignancy.

Adult↗