Aron Sobin

Cisplatin: Evaluation of its ototoxic potential*

The ototoxic potential of cisplatin was analyzed in an organ culture model exposing the hair cells and other inner ear structures to cisplatin doses from 0.1 to 10 micrograms/ml. Selective hair cell degeneration was obvious at concentrations of 0.1 microgram/ml. Incubation with 1 microgram/ml caused morphologic damage in the supporting cells in both the cochlear and vestibular parts of the labyrinth. Exposure to 10 micrograms/ml during five days caused a total collapse of the membranous labyrinth. The morphologic degeneration pattern at the ultrastructural level is nonspecific, except that nuclear chromatin was either swollen and disintegrated or considerably condensed. Based on inner ear concentrations equivalent to aminoglycoside antibiotics in the range of 0.1 to 10 micrograms/ml, cisplatin is, in the in vitro model used in this study, the most ototoxic drug known. However, because of its single dose administration and long intervals between administration, clinical ototoxicity is less pronounced than that from aminoglycoside antibiotics.

Histological Grading of Malignancy in Squamous Cell Carcinoma of the Oral Tongue

A system for histological grading of malignancy was applied to ninety-five squamous cell carcinomas from the anterior 2/3 of the tongue. Three parameters relating to the tumour cell population and three parameters relating to the tumour-host relationship were evaluated. The expected 5-year survival expressed as % survivors was 88% for patients with tumours having total malignancy scores of less than 13 points. 65% for 13-16 and 44% for patients with tumours having scores of more than 16. The prognostic significance for 5-year survival was statistically valid for the three different groups of malignancy scoring. The conventional classification according to mode of differentiation did not give equally good correlations for survival or occurrence of metastases. For the evaluation of the biological behaviour of lingual carcinomas, histological grading of malignancy is a better method.

Immunohistochemical Identification and Localization of Actin and Fimbrin in Vestibular Hair Cells in the Normal Guinea Pig and in A Strain of the Waltzing Guinea Pig

Using immunohistochemical methods, actin and fimbrin were identified and localized in vestibular epithelia iin the normal guinea pig and in the waltzing guinea pig. In the normal guinea pig, actin was found in the stereocilia and in the cuticular plate. Fimbrin was detected in the stereocilia but surprisingly not in the cuticular plate. As fimbrin was found in the cuticular plates in cochlear hair cells it is suggested that the hair cells in the two organs have different mechanoreceptor properties which can demand different cuticular plate stability. In the waltzing guinea pig, actin was found in the stereocilia, in the rod and n the cuticular plate. Fimbrin was seen in the stereocilia and in the rod, but could not be detected in the cuticular plate. These results emphasize the resemblance between the rod and the stereocilia. It is suggested that the rod is a genetically induced pathological intracellular type of stereocilium which grows in an uncontrolled manner.

Vestibular hair cell pathology in the Shaker-2 mouse

SummaryThe circling-waltzing behaviour of the Shaker-2 mouse is suggested, at least in part, to be of peripheral origin. In this hereditary inner ear disease, degeneration of hair cells type I has been observed showing specific pathologic features: rod-shaped inclusion bodies and sensory hair fusion. Later, the hair cells type I are expelled into the endolymphatic space. A large number of sensory cells type II are morphologically normal. The failure of earlier investigators to demonstrate pathological changes in the sensory epithelia of this animal is likely to be due to the use of light microscopical methods only.

Rods of actin filaments in type I hair cells of the shaker-2 mouse

ZusammenfassungShaker-2-Mäuse leiden an einer erblich bedingten Erkrankung, die sich in einer Taubheit und in einem Schüttel-Dreh-Verhalten äußert. Die Haarzellen vom Typ I in den Cristae ampullares und in den Maculae utriculi zeigen spezielle pathologische Veränderungen. So zeigen sich Zusammenklumpungen der Stereozilien neben stabförmigen Einschlußkörperchen. Die Einschlußkörperchen bestehen aus Filamenten, die als Actinprotein mit Hilfe einer Ankopplung von S-1-Myosin-Bestandteilen identifiziert werden konnten. Die Polarität wurde bestimmt und die Spitzen weisen nach apikal, d. h. vom Kern in Richtung zur Cuticularplatte hin. Diese Beobachtungen stimmen mit früheren überein, die bei Meerschweinchen mit der gleichen Erbkrankheit gefunden wurden. Daraus kann man schlußfolgern, daß die gleichen pathologischen Befunde in den Zellen von zwei unterschiedlichen Tierarten darauf hinweisen, daß die pathologische Veränderung in einem grundsätzlichen Prozeß für die Entwicklung dieses Haarzelltyps verantwortlich ist.SummaryThe shaker-2 mouse with inherited inner ear disease suffers from deafness and a shaking-waltzing behavior. The hair cell type I in cristae ampullares and maculae utriculi show a specific pathology, featuring fusion of the stereocilia and presence of a rod-shaped inclusion body. The inclusion body is composed of filaments that could be identified as the protein actin by the method of decoration with subfragment S-1 of myosin. The functional polarity was determined, and S-1 fragments were found to point apically, that is, from the nucleus up toward the cuticular plate. These observations are identical to those earlier described in the waltzing guinea pig. It is concluded that the identical pathology at a cellular level in two different species may indicate a pathologic disorder in a process fundamental to the normal development of this type of hair cell.

Ethacrynic acid effects on the isolated inner ear: Evaluation of the ototoxic potential in an organ culture system

The ototoxic potential of ethacrynic acid, defined as causing morphologic damage to hair cells or adjacent supporting structures, was analyzed in an organ culture model exposing inner ear structures to concentrations attainable during clinical conditions (0.1 to 10 micrograms/ml). In low doses more) ethacrynic acid caused generalized toxic effects on the tissue morphology of many types of inner ear tissues and an arrest of tissue differentiation. Although by definition ethacrynic acid is an ototoxic agent, there is, at least in the in vitro system, a very narrow dose range between the selective hair cell damaging concentration and that causing generalized toxic effects.

Sensory Hairs and Filament Rods in Vestibular Hair Cells of the Waltzing Guinea Pig. Organization and Identification of Actin

The waltzing guinea pig suffers from hereditary deafness and vestibular disorder. In vestibular organs, hair cells of Type I develop pathologically and will eventually degenerate. They show fusion of sensory hairs, protrusion of the cuticular plate and contain a rod-shaped inclusion body. With fixation techniques designed to preserve proteins it is shown that this rod has a filamentous substructure reminding one of stereocilia. The packing density of the filaments is similar and circular packing patterns are seen within both structures. However, the rod has an irregular cross-section, as opposed to the circular circumference of stereocilia. The filaments in the rod were identified as containing the protein actin (as those in the stereocilia) by decoration with sub-fragment S-1 of myosin. All filaments in the rod have an identical functional polarity, pointing up from the nucleus towards the cuticular plate. This is contrary to that seen in stereocilia, which have filaments pointing down towards the cuticular plate. It is concluded that the rod is not developed by random polymerization of actin but is the result of co-ordinated assembly reminiscent of that which gives rise to stereocilia. The genetic defect appears to be related to mechanisms which determine the site of nucleation and the functional orientation of actin filaments during development.

Early development of cochlear hair cell stereociliary surface morphology

SummaryThe early development of the surface structures of differentiating cochlear hair cells (guinea-pig) was analysed by scanning electron microscopy (SEM). A basal-to-apical gradient was evident in hair cell maturation. Inner hair cells developed before outer hair cells at the same level in the cochlea. The first sign of the onset of hair cell differentiation was a regularization of the pattern of microvilli on the future hair cell. Later, the cluster of regularized microvilli was rebuilt to form the stereociliary bundle, with a stepwise increase in the length of those stereocilia facing the stria vascularis.

Principles in embryonic development and differentiation of vestibular hair cells.

The early development and maturation of vestibular hair cells in the CBA/CBA mouse were analyzed at the ultrastructural level with conventional transmission electron microscopy and freeze fracturing. Cells differentiating into future hair cells pass their terminal mitosis close to the otocyst lumen. The earliest morphologic sign of differentiation into future hair cells was the arrangement of microvilli in a regular fashion. Hair cell cytodifferentiation occurred with a gradient from the hair cell surface to the base. In parallel with the maturation of sensory hairs a structural intracellular rebuilding occurred: the number of polyribosomes and amount of rough endoplasmic reticulum decreased, the nucleus moved basally, and mitochondria accumulated in the supranuclear region. Both tight junctions and gap junctions occurred initially on developing hair cells. From the sixteenth gestational day on, gap junctions disappeared, indicating an uncoupling phenomenon. Afferent nerve terminals developed before efferent nerve endings. Maturation of innervation occurred, for the most part, postnatally, and after that hair cells reached mature morphology.

Combined preoperative radiotherapy and surgery in the treatment of carcinoma of the anterior two-thirds of the tongue†

Sixty‐three patients with squamous cell carcinoma of the anterior two‐thirds of the tongue were treated with preoperative external radiotherapy (mean target dose 42.60 Gray or 4260 rad) and surgery. The expected 5‐year survival, expressed as life table estimate of percent of survivors, was 77% for patients with Stage I tumors, 69% with Stage II, and 13% for patients with tumors in Stages III‐IV (p < 0.001). Fourteen patients experienced local recurrences, 7 had homolateral neck metastases, 4 had contralateral neck metastases and 3 had distant metastases. In 15 cases no cancer could be detected at review of the surgical specimens, but 2 of these died of their cancers. In 43 cases cancer was present in the specimens, and 26 of these died of their cancer (p < 0.01).