A comparative study of chemically induced DNA damage in isolated nasal mucosa cells of humans and rats assessed by the alkaline comet assay.

Single-cell microgel electrophoresis (comet) assay was used to study genotoxic effects in human nasal mucosa cells and rat nasal and ethmoidal mucosa cells in vitro. Human cells were obtained from tissue samples of 10 patients (3 females/7 males), who underwent surgery (conchotomy) for treatment of nasal airway obstruction. Rat nasal mucosa cells were derived from male Sprague-Dawley rats. Cells were exposed for 1 h to either N-nitrosodiethanolamine (NDELA), epichlorohydrin (EPI), 1,2-epoxybutane (EPB), ethylene dibromide (EDB), or 1,2-dibromo-3-chloropropane (DBCP). Dimethyl sulfoxide (DMSO) was used as negative control. Alkaline comet assay was performed according to a standard protocol and DNA damage was quantified as Olive tail moment using image analysis system. All test substances induced an increase in DNA damage in human and rat cells. The absolute amount of DNA damage in rat nasal mucosa cells was usually higher than in ethmoidal mucosa cells. Human nasal mucosa cells were found to be less sensitive than rat mucosa cells to the genotoxic activities of DBCP (lowest effective concentration in human cells [LEC(human)]: 1.5, in rat cells [LEC(rat)]: 0.01 mM) and NDELA (LEC(human): 25, LEC(rat): 12.5 mM), whereas EPB-treated cells were almost equal (LEC(human) and LEC(rat) 0.78 mM). NDELA induced a marked concomitant cytotoxicity. For EPI (LEC(human) and LEC(rat): 0.097 mM) and EDB (LEC(human): 0.195, LEC(rat): 0.048 mM), pronounced interindividual differences were observed in human samples.

Study of osteointegration of a titanium prosthesis to the stapes: observations on an accidentally extracted stapes.

BACKGROUND: Titanium is a well-established implant material, and its use in ossicular chain reconstruction during middle ear surgery is increasing. HYPOTHESIS: Bony fixation of titanium prostheses has to be considered using this material. Contact with bony structures of the middle ear may result in immobilization. In revision procedures, there is a potential risk of damaging or extracting adherent structures such as the stapes. METHODS: This is a case report of an accidentally extracted stapes resulting from bony fixation of a titanium prosthesis in revision tympanoplasty. The surgical specimen was examined by microscopy, histology, and scanning electron microscopy. Energy dispersive x-ray analysis was used to confirm the elemental composition of the extracted stapes and the titanium prosthesis. RESULTS: The prosthesis showed good biocompatibility at the implantation site, with signs of bone resorption of the stapes suprastructure. However, bony fixation of the undersurface of the prosthesis foot to the stapes footplate was confirmed by ultrastructural analysis. CONCLUSION: In revision tympanoplasty, bony fixation of the titanium prosthesis should be considered.

Rare tumors of the internal auditory canal.

The study was performed to identify the incidence and histology of rare tumors with growth restricted to the internal auditory canal (IAC) that are different from vestibular schwannoma (VS). Furthermore, the question was addressed whether a preoperative diagnosis would be possible in these cases. A series of 351 patients that were operated on for IAC tumors through a transtemporal or translabyrinthine approach was investigated retrospectively. Cases with a tumor entity other than VS were analyzed for symptoms, radiological diagnosis, intraoperative findings and postoperative histolopatology to determine if a differential diagnosis to the common VS can be established prior to surgery. In 15 out of 351 cases (4.3%), uncommon processes of the IAC were determined by histology (6 lipomas, 3 hemangiomas, 2 neurofibromas, 2 menigiomas, 1 facial neuroma and 1 case of bilateral malignant lymphoma). The symptoms and the clinical manifestations were typical for patients with VS so that a preoperative differential diagnosis was not possible in the majority of cases. An analysis of the operation reports revealed that in 10 out of the 15 cases the surgeon suspected an unusual tumor of the IAC during surgery. The results of the present investigation suggest that rare lesions of the IAC can be expected in less than 5% of the cases and that preoperative diagnosis of rare IAC tumors is difficult. Intraoperative findings such as adhesion to cranial nerves and consistency of the tumor often indicate unusual processes, but histological analysis of the removed tissue is essential for the definite diagnosis.

Cytokeratin expression pattern in congenital and acquired pediatric cholesteatoma.

Pediatric cholesteatoma can be classified as congenital or acquired based on clinical criteria. We studied the expression patterns of five distinctive cytokeratins in both types of cholesteatoma in order to improve understanding of their pathogenesis and origin. A comparable expression pattern for CK10, CK14, CK18, CK19 and 34betaE12 antigens was found in the matrix of congenital and acquired pediatric cholesteatoma. Our results demonstrate that congenital and acquired pediatric cholesteatoma exhibit an identical cytokeratin distribution pattern, suggesting that they share a common origin. Therefore, it seems possible that a portion of the so-called "acquired" cholesteatoma may actually originate from advanced congenital cholesteatoma with secondary destruction of the tympanic membrane in the pediatric patient population.

Etiopathogenesis of cholesteatoma.

Cholesteatoma is a destructive lesion of the temporal bone that gradually expands and causes complications by erosion of the adjacent bony structures. Bone resorption can result in destruction of the ossicular chain and otic capsule with consecutive hearing loss, vestibular dysfunction, facial paralysis and intracranial complications. Surgery is the only treatment of choice. The etiopathogenesis of cholesteatoma, however, is still controversial. This review was designed to understand the reasons for these disparities and to reduce or eliminate them. Future studies focused on developmental, epidemiological, hormonal and genetic factors as well as on treatment are likely to contribute to further understanding of cholesteatoma pathogenesis.

Zoledronic acid inhibits osteoclastogenesis in vitro and in a mouse model of inflammatory osteolysis.

This study assessed effects of the bisphosphonate zoledronic acid (ZLNA) on osteoclastogenesis. To assess the effect of ZLNA on osteoclast formation in vitro, we cultured mouse bone marrow cells under conditions that promote osteoclastogenesis. Administered at concentrations from 10(-6) to 10(-9) mol/L, ZLNA led to a dose-dependent inhibition of osteoclastogenesis. Combined TUNEL staining and histochemical staining for tartrate-resistant acid phosphatase showed that ZLNA induced apoptosis in osteoclasts and monocytic precursor cells. To study the effects of ZLNA in vivo, we placed keratin particles onto the surface of the parietal bone of mice to induce localized inflammatory bone resorption. Three experimental groups received daily subcutaneous injections of ZLNA (1, 3, or 10 microg/kg body weight) from 4 days before surgery until 5 days after keratin implantation. The ZLNA significantly reduced osteoclast recruitment in a dose-dependent manner, but did not affect the degree of inflammation or the mineral apposition rate.

Inflammation of embryonic connective tissue in the middle ear spaces.

OBJECTIVE: Persistent embryonic connective tissue has been considered to be a cause of chronic otitis media with effusion in neonates and of cholesteatoma in later life. As part of a study of pneumatization and resorption of embryonic connective tissue from the middle ear of pre- and postnatal infants, inflammatory processes of variable extents have been observed within the embryonic connective tissue. The aim of the present study was to characterize this inflammation and to detect patterns in its presence and distribution. MATERIAL AND METHODS: Twenty fetal temporal bones obtained at 4-8 months of development and 31 temporal bones from children who died of sudden infant death syndrome aged < 1 year were studied to assess the inflammation within the middle ear cleft and specifically in the embryonic connective tissue. RESULTS: Sixteen of 27 (59.3%) pre- and 10/31 (32.2%) postnatal specimens displayed a non-specific inflammatory lymphocytic infiltration without signs of bacterial infection or the presence of or reaction to amniotic contents. Eleven of 27 prenatal temporal bones (40.7%) and 16/31 (51.6%) postnatal specimens showed no evidence of histologic middle ear inflammation. The presence or absence of inflammation was independent of age. CONCLUSION: Our observations indicate resorption of the embryonic connective tissue with individual variations indicating that genetic factors are responsible for the development of the middle ear spaces during the phases of development studied.

A murine model of cholesteatoma-induced bone resorption using autologous dermal implantation.

OBJECTIVE: To investigate a novel murine model for dermal implant-induced osteolysis analogous to bone resorption observed in middle ear cholesteatoma. STUDY DESIGN: Animal experiment. METHODS: We placed autologous dermal implants on the surface of mouse calvaria. The calvaria were examined at days 1, 3, 5, 7, and 14 after implantation by histological study and tartrate-resistant acid phosphatase immunohistochemical processing to detect osteoclasts. RESULTS: Dermal implants showed a significantly increased osteoclast density compared with control samples. The dermal implant tissue remained viable and produced a robust, localized inflammatory osteolytic response on the adjacent calvarial surface. Osteoclasts were predominantly found on the surface of the calvarium with the greatest osteoclast density seen at 5 to 7 days after implantation. CONCLUSION: The mouse model is expected to be a useful tool for investigating the pathogenesis of localized inflammatory bone resorption related to cholesteatoma.

Evidence against neonatal aspiration of keratinizing epithelium as a cause of congenital cholesteatoma.

OBJECTIVES/HYPOTHESIS: It has been suggested that congenital cholesteatoma may be caused by perinatal aspiration of squamous epithelium. STUDY DESIGN: Microscopic study of fetal temporal bones. METHODS: Thirty-one temporal bones from infants who died of sudden infant death syndrome before 1 year of age and 27 temporal bones obtained from preterm fetal deaths aged 4 to 8 months of fetal development were studied to assess signs of aspiration of squamous epithelium in the middle ear. RESULTS: None of the prenatal or postnatal temporal bones showed keratinizing epithelial cells or lanugo. A certain number of specimens displayed a nonspecific inflammatory lymphocytic infiltration. CONCLUSION: The data in the present study do not support the theory of amniotic fluid and squamous epithelial aspiration as an origin of congenital cholesteatoma.

Osteoclast stimulating and differentiating factors in human cholesteatoma.

OBJECTIVES: To investigate the expression of osteoclast-activating and differentiating factors and to study the occurrence of osteoclast precursor cells and osteoclasts in acquired human cholesteatoma tissue. METHODS: We examined 21 cholesteatoma samples versus 18 normal auditory canal skin specimens for the expression of osteoprotegerin ligand (OPGL), osteoprotegerin (OPG), and macrophage-colony stimulating factor (M-CSF) using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Immunohistochemistry and computer-assisted microscopy using markers CD4, CD11a, CD11b, CD14, CD51, CD68, and TRAP obtained the detection of osteoclast cell lineage. RESULTS: An increased expression of the investigated cytokines M-CSF, OPG, and OPGL was demonstrated by immunohistochemistry and RT-PCR in cholesteatoma tissue compared with normal external meatal skin. Several CD4-positive cells exhibited a co-expression for OPGL within the perimatrix of cholesteatoma. The presence of osteoclast precursor cells was confirmed in all samples of cholesteatoma tissue. CONCLUSIONS: This study reveals that the number of osteoclast precursor cells is markedly increased in the perimatrix of cholesteatoma tissue. Our results support a concept described for inflammatory arthritis: the inflammation related to cholesteatoma induces bone resorption by release of OPGL from activated T-cells and triggers osteoclastogenesis. This could be a major target for drugs to inhibit osteoclast formation and bone resorption and may be an adjunct in cholesteatoma management.

Cirugía de las malformacions mayores de oído / Surgery of the ear over malformacions

En el presente trabajo quiere informar al otolaringólogo de los pasos funfamentales de la cirugía de las atresias. Por razones embriológicas la articulación temporomandibular es retroplazada y se apoya a la pared anterior de la mastoides por falta de desarrollo del anillo timpánico. En consecuencia una parte de la caja se esconde detrás de la articulación y el neoconducto no puede ser formado en la posición normal. En muchos pacientes la situación anatómica no permite la cirugía reconstructiva. La selección cuidadosa de los casos favorables a base de la tomografía computarizada evita operaciones inútiles.

This paper intends to give a general information to the otolaryngologist on the basic steps in atresia surgery. In most cases the tympanic ring which in embryologic development eventually forms the outer ear canal is missing. Therefore the temporomandibular joint is placed backward towards the anterior wall of the mastoid. In consequence the middle ear space is partially hidden behind the articulation and cannot be reached by direct drilling in the normal position. The surgeon has to form the new canal through the mastoid. A considerable number of cases cannot be operated for anatomical reasons. A careful selection of the favorable cases based on computerized tomography avoids unessceessary surgery.

Transplantes e implantes en la cirugía del oído medio / Transplant and you implants in the middle ear

El autor muestra en el presente trabajo las diferentes opciones que hay de manejo de la cadena osicular del oído medio por alteraciones de esta en diferentes circunstancias. Se hace mensión de las posibilidades de utilización de diferentes elementos para la reconstrucción de la cadena osicular como pueden ser (hueso, diente, cartilago, metales, cerámicas, polietileno, cemento dental, etc.) muestra en el presente artículo la s estadísticas en este tipo de reconstrucción.

The author shows different options in the ossicular chain management because in different circumstances. He describes some possibilities about using a variety of elements for the ossicular chain reconstruction such as bone, teeth, polythelene, metals, ceramic, cartilage, dental clay, etc. Finally statistics abut tis kind of reconstruction is also detailed.