Seong Kook Park

Protective Effect of Corticosteroid against the Cytotoxicity of Aminoglycoside Otic Drops on Isolated Cochlear Outer Hair Cells

Objectives Otic drops are commonly used not only for otitis externa but also for otorrhea in the presence of tympanic membrane perforation or tympanostomy tube. Many studies demonstrated the ototoxicity of aminoglycoside. In our previous study, we observed that gentamicin (GM), when activated with liver extract, demonstrated significant cytotoxicity. The purpose of this study was to assess the protective effect of corticosteroid against the cytotoxicity of GM and tobramycin drops using isolated cochlear outer hair cells (OHCs) in vitro with liver extract.

Effects of nitric oxide on morphology of isolated cochlear outer hair cells: Possible involvement in sensorineural hearing loss

Hypothesis One of the inflammatory mediators of otitis media, nitric oxide, can damage cochlear outer hair cells. Background Free radicals, including nitric oxide, have been detected in middle ear effusion. Increasing evidence implicates free radicals in the pathogenesis of otitis media and possibly in the development of sensorineural hearing loss. Methods Isolated outer hair cells from adult chinchilla cochlea were exposed to standard bathing solution (Control Group 1) or the nitric oxide-producing compounds, S-nitroso-N-acetyl, l-penicillamine (1–1.5 mg/ml, Experimental Group 1) or 3-morpholinosynonimine (1–1.5 mg/ml, Experimental Group 2). Since nitric oxide is readily converted to nitrite and nitrate in vivo, a second control group using sodium nitrite was used to separate potential effects of nitric oxide from nitrite (Control Group 2). All experiments were performed at an osmolality of 305 ± 5 mOsm at room temperature, and with exposure time up to 90 minutes. The cells were observed using an inverted microscope, and the images were recorded and analyzed on the IMAGE Pro-Plus program. Results Outer hair cells exposed to either standard bathing solution or sodium nitrite (Control Groups 1 and 2) showed no significant change in cell shape or length. Cells exposed to S-nitroso-N-acetyl and l-penicillamine or 3-morpholinosynonimine exhibited ballooning and significant shortening in mean cell length (p < 0.01). Conclusion This study demonstrates that exposure to nitric oxide causes irreversible morphologic changes in isolated outer hair cells, suggesting possible involvement of nitric oxide radical in the development of sensorineural hearing loss as a sequela of chronic otitis media.

Effect of topical dexamethasone versus rimexolone on middle ear inflammation in experimental otitis media with effusion

Conclusion. The lipopolysaccharide (LPS)-induced chinchilla otitis media (OM) model was proven useful in screening anti-inflammatory agents for topical use. Both 1% rimexolone and 1% dexamethasone are effective in reducing the volume of middle ear effusion and mucosal thickness compared with control groups. Topical corticosteroid therapy was efficacious in reducing middle ear mucosal inflammation. Objective. OM is one of the most common diseases in the pediatric population. Our previous studies have shown that treatment with systemic antibiotics and corticosteroids was more efficacious than antibiotics alone. The purpose of this study was to determine the effectiveness of topically applied corticosteroids on the outcome of OM. The long-term goal of this study was to develop a better method of OM treatment by demonstrating effectiveness of topically applied anti-inflammatory agents, such as corticosteroids, avoiding systemic side effects. Materials and methods. Three experimental groups were studied in chinchillas. OM with effusion was induced in all groups by injecting LPS. Group 1 consisted of controls in three subgroups as follows. Control-LPS alone, vehicle of dexamethasone (control-dexa), vehicle of rimexolone (control-rimex). Group 2 was treated with dexamethasone and included subgroups of separate concentrations of dexamethasone: 0.1% and 1% suspensions. Group 3 was treated with rimexolone and included subgroups of separate concentrations of rimexolone: 0.1% and 1% suspensions. A total of 58 animals were used: 18 for controls and 40 for experimental groups. All test substances (saline, control-dexa, control-rimex, dexamethasone and rimexolone, 200 µl) were injected at −2, 48 and 60 h; LPS was injected at 0 h. Animals were monitored by daily otomicroscopy. After 4 days, samples of middle ear effusion (MEE) were collected for analysis and temporal bones were harvested for histopathological studies. Results. At the end of 4 days, only in five ears (3/20 with 1% dexamethasone, 1/20 with 1% rimexolone, and 1/20 with 0.1% rimexolone) had the fluid diminished to the point of being unobservable. The volume of MEE, thickness of mucoperiosteum, and the degree of inflammation of middle ear mucosa with 1% dexamethasone and 1% rimexolone was significantly less compared with other groups.

Expression of Chitinases in Hypertrophied Adenoids of Children

Objectives/Hypothesis. Chronic rhinosinusitis (CRS), otitis media with effusion (OME), and allergic rhinitis (AR) are common conditions that have been associated with hypertrophied adenoids in children, and adenoidectomy is clinically recommended. The investigators assayed the expression level and site of acidic mammalian chitinase (AMCase) and chitotriosidase (ChT) in hypertrophied adenoids of children to determine the expression levels of 2 chitinases in relation to CRS, OME, and AR. Study Design. A prospective cohort study. Setting. A tertiary care facility. Methods. Hypertrophied adenoids from 41 children were harvested during adenoidectomy. Medical records were reviewed and the subjects were grouped according to the presence of CRS, OME, and AR. Messenger RNA (mRNA) and protein expression of AMCase and ChT in adenoid tissues was assessed by reverse transcription polymerase chain reaction and Western blotting. Immunohistochemical staining revealed the sites of AMCase and ChT expression. Results. mRNA and protein of AMCase and ChT were present in adenoids of all subjects. CRS was a significant variable in AMCase mRNA and protein expression. CRS, OME, and AR were significant variables in ChT mRNA and protein expression. Both AMCase and ChT were expressed in histiocytes and vascular endothelial cells of adenoid tissues. Conclusions. The findings suggest that chitin-containing pathogens or dysregulated immune responses to them in the hypertrophied adenoids of children could be factors contributing to CRS, OME, and AR via AMCase or ChT overexpression.

Localized bilateral paranasal mucormycosis: a case in an immunocompetent patient

Mucormycosis of the nasal cavity and paranasal sinuses is an uncommon opportunistic fungal infection, which often has an aggressive, life-threatening course. Patients who have this condition are generally diabetic or immunosuppressed. However, mucormycosis can also occur in immunocompetent individuals. The most effective treatment consists of reversal of the source of immunocompromise, immediate surgical debridement and administration of systemic amphotericin B. No consensus has been reached regarding the appropriate surgical treatment or the total dose of amphotericin B. We present the case of a patient suffering from localized bilateral paranasal mucormycosis who was treated by means of endoscopic sinus surgery and administration of systemic amphotericin B. We suggest that endoscopic sinus surgery is the choice of treatment for localized paranasal mucormycosis in an immunocompetent patient, and that the total dose of amphotericin B can be determined by the extent of disease and the postoperative endoscopic findings.

Chitinolytic activity in nasal polyps.

Background Chitin is a recognition element for tissue infiltration by innate cells implicated in allergy and immunity. This process can be negatively regulated by vertebrate chitinases. Both acidic mammalian chitinase (AMCase) and chitotriosidase (ChT) have chitinolytic activity. This study aimed to determine the activities of AMCase and ChT in nasal polyps (NPs), as well as their in situ localization in NP tissue. Methods AMCase and ChT activities in NPs were compared with those in inferior turbinate tissue samples. Tissue samples were measured for AMCase and ChT activities at a range of pHs using the fluorogenic substrate 4-methylumbelliferyl-beta-D-N,N′,N″-triacetyl-chitotriose. Double immunofluorescent staining for the localization of both AMCase and ChT was performed using NP cryosections. Results Both AMCase and ChT displayed markedly increased chitinolytic activity in all NPs, compared with inferior turbinate tissues. Double immunofluorescent staining revealed that CD68 highlighted monocytes in the submucosa of NP and these cells disclosed coexpression of AMCase and ChT. CD31 detected capillary endothelial cells, but did not express any AMCase and ChT. Conclusion The increased chitinolytic activities of AMCase and ChT in NPs may be important in NP pathogenesis, suggesting that inhibition of chitinolytic activity may be a novel therapeutic strategy for the treatment of NPs.

Effects of methotrexate on vascular endothelial growth factor, angiopoietin 1, and angiopoietin 2 in nasal polyps.

Background Methotrexate (MTX) is a very effective treatment for chronic inflammatory diseases, which are often associated with increased angiogenesis. Angiogenesis is dependent on a perfectly coordinated balance between endogenous-positive and -negative regulatory factors, including vascular endothelial growth factor (VEGF) and the angiopoietins (Ang). The aim of this study was to investigate the effects of MTX on levels of VEGF, Ang-1, and Ang-2 in organ-cultured nasal polyps (NPs. Methods To determine the effects of MTX, NP tissues were cultured using an air-liquid interface method. Cultures were maintained in the absence or presence of MTX (10 or 100 micromoles) for 24 hours. Hematoxylin and eosin, and TUNEL (terminal deoxynucleotidyl transferase [Tdt]-mediated dUTP-biotin nick-end labeling) staining were performed to observe apoptosis. Enzyme-linked immunosorbent assay was used to quantify tissue concentrations of VEGF, Ang-1, and Ang-2. Results MTX treatment resulted in marked alterations in inflammatory cells, especially eosinophils. In contrast, the mucosal epithelium, microvessels including arterioles, veins and capillaries, and fibroblasts maintained their structure. TUNEL+ cells (apoptotic cells) were seen in the MTX-treated specimens. The more induction of TUNEL+ cells was observed 100-micromolar MTX-treated specimens. VEGF and Ang-1 levels were significantly lower, and Ang-2 levels were significantly higher in NPs treated with 100-micromolar MTX than in nontreated NPs (p < 0.01. Conclusion MTX may inhibit the growth of NPs via local regulation of VEGF, Ang-1, and Ang-2 protein levels. We suggest that MTX can be used to treat NPs.

Medial or medio-lateral graft tympanoplasty for repair of tympanic membrane perforation

OBJECTIVE To describe and evaluate the medio-lateral graft tympanoplasty(1) for the reconstruction of anterior or subtotal tympanic membrane (TM) perforation and medial graft tympanoplasty for posterior TM perforation. METHODS Retrospective study of 200 patients who underwent medio-lateral graft tympanoplasty (100 cases) and medial graft tympanoplasty (100 cases) at community and tertiary care medical centers from 1995 to 2006. All patients underwent preoperative and postoperative audiograms. In the medial graft tympanoplasty, the graft is placed entirely medial to the remaining TM and malleus. First, margin of TM perforation is denuded removing ring of squamous tissue. Tympanomeatal flap is elevated. Temporalis fascia is harvested, semidried, and grafted medial to the TM perforation and malleus with Gelfoam packing supporting the graft. In the medio-lateral graft technique, posterior tympanomeatal flap is elevated same as in the medial graft tympanoplasty first. Anterior-medial canal skin is elevated down to the annulus. At the annulus only squamous epithelial layer of TM is elevated up to anterior half of the TM perforation. Temporalis fascia is grafted medial to posterior half of the perforation and lateral to anterior half of the de-epithelialized TM perforation up to the annulus. Anterior canal skin is rotated to cover the fascia graft and TM perforation as a second layer closure. Patients were followed for at least six months. Outcome was considered successful if TM is healed and intact. RESULTS There were four failures (96% success rate) in medial graft method for posterior TM perforation due to infection and re-perforation. In the medio-lateral graft tympanoplasty, there were three failures (97% success rate) due to a postoperative infection, anterior blunting and recurrent cholesteatoma. CONCLUSION The medial graft tympanoplasty works well for posterior TM perforation. The medio-lateral graft method is an excellent method for the reconstruction of large anterior or subtotal TM perforation. This new method should help otologic surgeons to improve outcome of tympanoplasty for anterior or subtotal TM perforation.

Effect of Corticosteroid on Salicylate-Induced Morphological Changes of Isolated Cochlear Outer Hair Cells

Our previous studies showed that pretreatment with corticosteroids, which inhibits release of arachidonic acid (precursor of prostaglandins and leukotrienes), partially prevented salicylate-induced hearing loss in vivo. The purpose of this study was to determine the effect of pretreatment with corticosteroid (dexamethasone sodium phosphate) on isolated cochlear outer hair cells (OHCs) exposed to salicylate in vitro. Isolated OHCs from the chinchilla cochlea were exposed to salicylate with or without pretreatment with dexamethasone. Images were stored and analyzed on the Image program. The OHCs exposed to salicylate demonstrated a significant shortening in cell length. The OHCs exposed to salicylate after pretreatment with dexamethasone exhibited no significant change in cell length. We conclude that corticosteroid treatment of isolated OHCs is effective in blocking the morphological changes induced by salicylate. This study gives additional evidence that salicylate ototoxicity is mediated by alteration in the levels of arachidonic acid metabolites.

Effects of dexamethasone or methotrexate on chitinolytic activity in nasal polyps.

Background Chitin is a recognition element for tissue infiltration by innate cells implicated in allergy and immunity. This process can be negatively regulated by vertebrate chitinases. Chitinolytic activity is significantly increased in nasal polyps (NPs) compared with that in normal turbinate mucosa. Dexamethasone (DEX) or methotrexate (MTX) is an effective treatment for chronic inflammatory diseases. The aim of this study was to investigate the effects of DEX or MTX on chitinolytic activity in organ-cultured NPs. Methods NP tissues were cultured using an air–liquid interface culture model. Cultures were maintained for 24 hours in the absence or presence of DEX (10 or 100 micromolar) or MTX (10 or 100 micromolar). Acidic mammalian chitinase (AMCase) and chitotriosidase (ChT) activities in tissue samples were measured at a range of pH values by using the fluorogenic substrate 4-methylumbelliferyl-beta-D-N,N′,N″-triacetyl-chitotriose. Results AMCase and ChT chitinolytic activities were significantly lower in NPs treated with 100 micromolar DEX or 100 micromolar MTX than that in fresh or untreated NPs. AMCase chitinolytic activity tended to be lower in DEX-treated polyps than in MTX-treated polyps, although the difference was not statistically significant. Conclusion DEX or MTX reduced chitinolytic activity in NPs. We suggest that DEX or MTX may inhibit the growth of NPs via local regulation of NP chitinolytic activity.