Application of oxygen free radical scavengers to diminish the occurrence of myringosclerosis

Evaluation of aortic stiffness by echocardiography in tympanosclerosis patients

BACKGROUND AND AIMS

Tympanosclerosis (TS) is a scarring process that may occur during otitis media. Aortic stiffness (AS) is a significant predictor for the development of heart diseases due to its close relationship with atherosclerosis. Similar pathophysiological processes based on inflammation may explain both TS and AS formation. This study aimed to determine echocardiographically whether aortic elasticity is impaired in TS-detected patients and to correlate blood inflammatory parameters with TS and aortic elasticity.

METHODS

Ninety-eight participants diagnosed with chronic otitis media were enrolled in the study. TS-detected 42 participants were assigned to the study group, while 56 without TS constituted the control group. The two groups' demographic, clinical, echocardiographic, and laboratory characteristics were comparable.

RESULTS

Demographic, clinical, and laboratory parameter differences were insignificant. Hs-CRP, neutrophil-to-lymphocyte ratio, and systemic immune-inflammation index were significantly higher in the study group than in the control group (P=0.018, P=0.003, P=0.019, respectively). The study group had significantly lower aortic strain (11.80 ± 4.84 vs. 16.30 ± 3.91; P<0.001) and distensibility (5.23 ± 2.68 vs. 7.24 ± 2.89; P=0.001) values than the control group. The AS index was significantly higher in the study group than in the control group (4.81 ± 2.41 vs. 3.12 ± 1.02; P<0.001).

CONCLUSION

In TS-detected patients, AS parameters were found to be impaired. Aortic elasticity parameters measured by echocardiography, a non-invasive and easily accessible method, may signify early cardiovascular involvement in TS-developed patients.

Analysis of Risk Factors for Myringosclerosis Formation after Ventilation Tube Insertion

BACKGROUND

This study examined possible risk factors for myringosclerosis formation after ventilation tube insertion (VTI).

METHODS

A retrospective study was performed in a single tertiary referral center. A total of 582 patients who underwent VTI were enrolled in this study. Patients were divided into two groups based on the presence or absence of myringosclerosis: MS+ and MS-. Characteristics of patients were collected through medical chart review; these included age, gender, nature and duration of effusion, type of ventilation tube (VT), duration and frequency of VTI, incidence of post-VTI infection, incidence of intraoperative bleeding, and presence of postoperative perforation. Incidences of risk factors for myringosclerosis and the severity of myringosclerosis in association with possible risk factors were analyzed.

RESULTS

Myringosclerosis developed in 168 of 582 patients (28.9%) after VTI. Patients in the MS+ group had an older mean age than those in the MS- group. The rates of myringosclerosis were higher in patients with older age, serous otitis media, type 2 VT, post-VTI perforation, and frequent VTI. However, there were no differences in occurrence of myringosclerosis based on gender, duration of effusion, duration of VT placement, incidence of post-VTI infection, or incidence of intraoperative bleeding. The severity of myringosclerosis was associated with the duration of effusion and frequency of VTI.

CONCLUSION

Older age, serous effusion, type 2 VT, presence of post-VTI perforation, and frequent VTI may be risk factors for myringosclerosis after VTI; the severity of myringosclerosis may vary based on the duration of effusion and frequency of VTI.

Is there any effect of montelukast on prevention of myringosclerosis after myringotomy in a rat model?

OBJECTIVES

In this study, our aim was to identify the possible effects of montelukast sodium (ML) on the prevention of experimentally induced myringosclerosis.

MATERIALS AND METHODS

Twenty-eight female Wistar albino rats were used and they were divided into four groups randomly. Tympanic membranes (TM) of all animals were perforated and then group 1 received no treatment (control group), group 2 was treated with a topical saline solution, group 3 received topically ML and group 4 received orally ML. On the 15th day, all animals were euthanized. Tympanic membranes were evaluated otomicroscopically and histopathologically.

RESULTS

The histopathological findings, compared against a control and saline groups, showed the topically and orally ML groups had statistically significant differences of degree of myringosclerosis (p < 0.002) and median thickness of the TMs (p < 0.001). Suppression of inflammation was statistically significant only in the oral ML treatment group (p < 0.002).

CONCLUSION

Oral and topically administration of ML reduced myringosclerosis formation in myringotomies rats.

Does calcemia influence the onset of myringosclerosis after myringotomy with the insertion of ventilation tubes?

INTRODUCTION

Myringosclerosis is one of the most frequent late complications of the insertion of ventilation tubes, and its aetiopathogenesis remains unknown. The calcification that occurs in the formation of myringosclerosis plaque raises the hypothesis of the presence of a calcium metabolism disorder. The objective is to determine whether calcemia contributes to the development of myringoscelerosis after insertion of ventilation tubes.

MATERIAL AND METHODS

A longitudinal, prospective, analytical cohort study was conducted in patients undergoing myringotomy with the insertion of ventilation tubes due to otitis media with effusion. Calcemia was evaluated pre-operatively and in the follow-up the appearance of myringosclerosis and the percentage of the tympanum involved were evaluated.

RESULTS

The study included 156 patients (297 ears), with calcemia values ranging from 7.6 to 10.2mg/dl. Myringosclerosis was identified in 35.4% of the operated ears. No relationship was found between the appearance of myringosclerosis and calcemia (p=.596). It was found, however, that the greater the percentage of the tympanum affected by myringosclerosis, the lower the calcemia values (p=.014).

CONCLUSION

The population studied had calcemia values within the normal range, which allows us to infer that no changes in calcium metabolism are required for the development of myringosclerosis. Moreover, unlike in previous studies, higher calcium levels are not associated with more myringosclerosis. Calcemia did not influence the appearance of myringosclerosis after myringotomy with the insertion of ventilation tubes.

The effect of caffeic acid phenethyl ester (CAPE) on tympanosclerosis

OBJECTIVE

To investigate the effects of caffeic acid phenethyl ester (CAPE) on tympanosclerosis.

MATERIALS AND METHODS

Thirty-two male Sprague Dawley rats were separated into 4 groups as CAPE (n = 10), alcohol (n = 10), control (n = 8) and normal (n = 4) groups. All tympanic membranes except normal group were myringotomised and type 3 Streptococcus pneumoniae strains was injected into their middle ears. Myringotomies were repeated for 5 weeks. Intraperitoneal (i.p) CAPE were administrated to the CAPE group at 10 μmol/kg/day and 10% ethyl alcohol administrated to the alcohol group for 5 weeks. The control group were left untreated. Findings of myringosclerosis were recorded by otomicroscope at sixth week. Then, all rats were sacrificed and tympanic membrane thickness and severity of middle ear mucosal inflammation evaluated histopathalogically.

RESULTS

Severity of myringosclerosis was significantly higher in the alcohol and control groups compared to the CAPE group (p < 0.001), but was not significant when alcohol and control groups were compared (p = 0.17). The tympanic membrane thickness measured in the alcohol and control groups were significantly higher compared to the CAPE group (p < 0.001), but was not significant when alcohol and control groups were compared (p = 0.17). The severity of inflammation in the middle ear mucosa was significantly higher in the alcohol and control groups compared to the CAPE group (respectively, p < 0.001, p = 0.03). The severity of inflammation in the middle ear mucosa was not significant between alcohol and control groups (p = 0.30).

CONCLUSION

CAPE has anti-inflammatory and antioxidant effects on the development of MS in myringotomized rats, so reduces the severity of tympanosclerosis.

Effect of Topical Dexamethasone for Preventing Experimentally Induced Myringosclerosis

Objective

We aimed to examine the effect of topical dexamethasone by otomicroscopic and histologic examinations for preventing myringosclerosis induced by myringotomy in rat tympanic membranes.

Methods

Twenty-one Sprague Dawley rats (42 ears) were randomly divided into the following three groups after otomicroscopic examinations: experimental surgical group (5 rats), control group (8 rats), and study group (8 rats). The rats of all the groups underwent myringotomy in both tympanic membranes. Other than myringotomy, no additional procedure was performed for the rats in the experimental surgical group. In the control group, 0.9% NaCl was applied to the ears, whereas in the study groups, topical dexamethasone was applied to the ears. These applications in the control and study groups were repeated for nine days. On the 10th day of the study, the rat ears of all groups underwent otomicroscopic and histologic examinations. The prevalence and process of myringosclerosis were evaluated by otomicroscopic examination, whereas inflammation, membrane thickness, and myringosclerosis intensity were evaluated by histologic examination.

Results

The growth of myringosclerosis with otomicroscopic examination was lesser in the study group in which topical dexamethasone was applied than the control and the experimental surgical groups. Moreover, it was observed that myringosclerosis effected fewer quadrants in the study group.Histologic examinations revealed that inflammation was significantly lesser in the study group than in the experimental surgical and control groups. The average membrane thickness values were significantly lesser in the study group than in the experimental surgical group. With respect to myringosclerosis growth, no statistically significant difference was observed among all groups, whereas with respect to myringosclerosis intensity, the rat ears in the study group were less severely affected.

Conclusion

Thus, our study results suggest that applying topical dexamethasone after myringotomy has positive effects on limiting the intensity and prevalence of myringosclerosis.

Surgical Management of Myringosclerosis over an Entire Perforated Tympanic Membrane by Simple Underlay Myringoplasty

The aim of our study is to demonstrate the surgical management of myringosclerosis over a perforated whole tympanic membrane using simple underlay myringoplasty. Simple underlay myringoplasty with fibrin glue was performed in 11 ears with myringosclerosis over the entire tympanic membrane. The patients were one male and ten females and their mean age was 61.8 years (range, 40-73 yr). Surgical success was defined as an intact tympanic membrane 12 months after surgery. Closure of the perforation was successful in 10 (91%) of the 11 patients. Failure of the graft occurred in one patient who then underwent a revision procedure using her stored fascia in the outpatient clinic with a successful outcome. The overall success rate was 100%. Although this study included a small number of cases, removal of myringosclerosis at the edge of a perforation is a beneficial technique for simple underlay myringoplasty in terms of the success rate and postoperative hearing threshold, especially when myringosclerosis extends over the entire tympanic membrane.

The impact of topical and systemic enoxaparin sodium use on traumatic tympanic membrane perforation and myringosclerosis

The objective of this study is to investigate the effect of topical and systemic enoxaparin sodium on the healing pattern of experimentally induced tympanic membrane perforation and formation of myringosclerosis. A total of 24 Wistar-Albino strain rats were included in the study. Standard myringotomies were performed on each rat. In the first group, isotonic serum physiologic was dropped on external ear canal (control group). Topical enoxaparin was dropped on external ear canal and daily topical doses of enoxaparin were dropped on external ear canal of the rats for 14 days (topical treatment group). Third group received subcutaneous injections of enoxaparin for 14 days (systemic treatment group). Five micrometer thick sections of the bullae of the rats were stained with H&E. Inflammation, edema and sclerotic lesions and neovascularization observed in the lamina propria layer of the tympanic membrane, and total thickness of the tympanic membrane were evaluated. In intergroup comparisons, significant difference in the distribution pattern of severity of inflammation in all three groups was not observed (p = 0.784, p > 0.05). Total TM thickness differed among all three groups (p = 0.028, p < 0.05). A statistically significant difference was observed between the systemic enoxaparin and the control groups (p = 0.022, p < 0.05). A statistically significant difference was observed between the topical enoxaparin and the control groups (p = 0.037, p < 0.05). However, comparison between the topical and systemic treatment groups could not reveal any statistically significant intergroup difference (p = 0.682, p > 0.05). A significant difference was not observed among three groups as for the distribution of myringosclerotic plaques, severity of edema and neovascularization in the lamina propria (p = 0.539, p > 0.05), (p = 0.063, p > 0.05), (p = 0.152, p > 0.05). Topical and systemic enoxaparin treatment did not prevent formation of sclerotic plaques; however, it decreased TM thickness significantly in comparison with the control group.

Future opportunities in preventing ototoxicity: Caffeic acid phenethyl ester may be a candidate (Review)

Caffeic acid phenethyl ester (CAPE) is an important active component of propolis, which is derived from honeybee hives. It has received increasing attention in a variety of medical and pharmaceutical research, due to its anti‑oxidant, antiproliferative, anti‑inflammatory, antiviral and antifungal activity, in addition to its antineoplastic properties. Besides the use of CAPE as an antioxidant and anti‑inflammatory agent in a number of in vivo studies of ear disease, its beneficial effects have been reported in the treatment of cancer, arthritis, allergies, heart disease, diabetes, kidney disease, liver disease and neurological disease. CAPE influences a number of biochemical pathways, as well as several targets involved in ear diseases, in particular, in ototoxicity. The protective effects of CAPE in ototoxicity, which may be induced by a number factors, including lipopolysaccharides, hydrogen peroxide and streptomycin, are evaluated and discussed in the present review.

Do all antioxidant supplements have the same potential effect on preventing myringosclerosis?

Objectives

Myringosclerosis is an irreversible pathological healing mechanism of the tympanic membrane which can result in the formation of sclerotic plaques. Antioxidant treatment is a recognised prevention therapy and coenzyme Q10 (CoQ10), lycopene, and grape seed extract (GSE), were used in this manner.

Methods

Forty-four Wistar rats were used in this experiment, and, following myringotomies, the animals were randomly divided into four groups. CoQ10, lycopene or GSE was administered orally to the respective groups, starting from the day of surgery. Otomicroscopy examination was performed on the 14th day. All tympanic membrane lesions were evaluated and compared otomicroscopically and histopathologically.

Results

The otomicroscopy and histopathological findings, compared against a control (saline) group, showed the CoQ10, lycopene, and GSE groups had statistically significant differences of degree of sclerosis (P<0.001).

Conclusion

CoQ10, lycopene, and GSE were compared against a saline group and their antioxidative and anti-inflammatory effects were similar. The formation of myringosclerotic plagues after experimental myringotomy in rats significantly decreased and diminished after systemic administration of the three different antioxidant supplements.

Does systemic clarithromycin therapy have an inhibitory effect on tympanosclerosis? An experimental animal study

Objective:

To demonstrate the inhibitory effects of clarithromycin on in vitro tympanosclerosis.

Method:

Twenty-eight rats were divided into three groups: a clarithromycin group, a non-clarithromycin group and a negative control group. Those in the first two groups were injected with Streptococcus pneumoniae following a myringotomy, and tympanosclerosis was experimentally induced. Oral clarithromycin therapy was administered in the clarithromycin group. The other groups received no medical treatment.

Results:

All eardrums in the clarithromycin and non-clarithromycin groups developed myringosclerosis, but there was only one eardrum, in the clarithromycin group, with very severe myringosclerosis. In the clarithromycin group, 11 ears showed no inflammation and there were no ears with severe inflammation. In the non-clarithromycin group, there were 11 ears with severe inflammation. The mean eardrum thickness in the clarithromycin group was 20.93 µm and in the non-clarithromycin group it was 42.71 µm.

Conclusion:

Acute otitis media and myringotomies induced tympanosclerosis, but clarithromycin reduced the severity of tympanosclerosis.

Pepsin deteriorates prognosis of children with otitis media with effusion who undergo myringotomy or tympanostomy tube insertion

OBJECTIVE

To investigate the concentrations of pepsin and pepsinogen within the middle ear cavity and determine whether pepsin and pepsinogen affect the prognosis of children with otitis media with effusion (OME).

METHODS

All middle-ear lavage fluid from patients with OME undergoing myringotomy (M subgroup) or tympanostomy tube insertion (T subgroup) was collected and pepsin and pepsinogen were detected using enzyme-linked immunosorbent assay. After close follow-up over 2 years, the effects of pepsin and pepsinogen on the prognosis of the patients with OME in the M and T subgroups were analyzed.

RESULTS

The average pepsin and pepsinogen concentrations were significantly lower in the M subgroup (n=54; 24.38±16.10mg/mL and 286.49±91.95mg/mL, respectively) than in the T subgroup (n=55; 45.56±16.60mg/mL and 664.92±107.06mg/mL; t=2.484, P=0.018 and t=2.670, P=0.011, respectively). In the M subgroup, the average time to tympanic membrane healing and tympanic pressure restoration to normal was much longer in pepsin(+) patients (17.0±2.0 days and 26.0±2.5 days, respectively) than in pepsin(-) patients (14.0±1.1 days and 22.0±1.0 days; t=3.871, P=0.001 and t=5.734, P=0.000, respectively), and the hearing level of pepsin(+) patients with OME ascended to 13.08±1.19dB, which was much lower than that of pepsin(-) patients (18.29±1.27dB; t=11.001, P=0.000). In the T subgroup, the complication rate including otorrhea and myringosclerosis was much higher in patients with high pepsin concentrations than in those with low pepsin concentrations (P<0.05). Finally, in both subgroups, the recurrence rates of OME in pepsin(+) or patients with high pepsin concentrations (34.6% [9/26] and 28.6% [10/35]) were significantly higher than those in pepsin(-) or low pepsin concentrations (10.7% [3/28] and 5.0% [1/20]; χ(2)=4.456, P=0.035 and χ(2)=4.420, P=0.036). However, pepsinogen had no significant effect on OME prognosis or recurrence.

CONCLUSION

Pepsin but not pepsinogen could postpone tympanic membrane healing and pressure restoration in children with OME undergoing myringotomy and increase the incidence of recurrence and complications including otorrhea and myringosclerosis for those undergoing tympanostomy tube insertion. Therefore, pepsin could be considered a poor prognostic factor for OME, further emphasizing the important role of pepsin in OME pathogenesis.

Inhibitory effect of N-acetyl cysteine and ascorbic acid on the development of myringosclerosis: an experimental study

OBJECTIVES

This study investigated the effects of ascorbic acid and N-acetyl cysteine (NAC) antioxidants on the development of myringosclerosis (MS) in an experimental model.

METHODS

Myringotomies were performed in the ears of 15 guinea pigs, and Spongostan pieces were placed on the perforated regions of the tympanic membrane. The subjects were divided randomly into three groups and treated with three different solutions on the Spongostan-group 1: (control, 0.9% saline), group 2 (ascorbic acid), and group 3 (NAC). On day 15 after treatment, specimens from the tympanic membranes were obtained and examined via light microscopy. Sclerosis and inflammation scores and the tympanic membrane thicknesses were evaluated. Immunohistochemical methods were used to evaluate the expression of VEGF, TGF-β, iNOS, and IL1-β in all groups.

RESULTS

Lower sclerosis and inflammation scores and reduced tympanic membrane thicknesses were observed in groups treated with NAC or ascorbic acid compared with the control group. Immunohistochemical studies revealed significantly less expression of VEGF, TGF-β, and iNOS in groups 2 and 3 compared with group 1. Additionally, IL1-β expression was significantly less in group 3 than in group 1. Compared with group 1, group 2 animals exhibited reduced inflammation in the lamina propria, fewer active fibroblasts, less leukocyte infiltration, and decreased thickness of the vessels; group 3 animals exhibited decreased numbers of active fibroblasts and collagen fibers in the lamina propria.

CONCLUSIONS

Inflammation scores, cellular infiltration, and expression of VEGF, TGF-β, and iNOS were reduced by ascorbic acid and/or NAC treatments, thereby decreasing MS development. Decreased expression of IL1-β was observed only in animals treated with NAC.

Division of the stapedial tendon results in noise-induced damage to the inner ear

Background

The effect of division of the stapedial tendon on susceptibility to noise-induced inner ear damage has not been previously studied. This study aimed to evaluate the effects of noise exposure following division of the stapedial tendon in guinea pigs.

Material/Methods

Ten adult albino guinea pigs were used. The stapedial tendon of each right ear was cut. The stapedial tendon in each left ear was left intact and these ears served as a control group. DPOAEs and ABR tests were performed before and 10 days after noise exposure. The animals were exposed to a 110-dB noise stimulus for 6 h in a silent room a week after surgery. Cochleas of the animals were removed, and inner and outer hair cells were examined under a light microscope.

Results

We found that noise exposure adversely affected DPOAE measurements at all frequencies except 2 KHz in experimental ears. Noise exposure also produced significantly elevated ABR thresholds in experimental ears at 2, 4, 8, and 16 KHz. On histopathological examination, we found a significantly greater prevalence of apoptotic cells in the experimental ears.

Conclusions

Based on these findings, we can conclude that after division of the stapedial tendon, noise exposure may cause damage to the inner ear. This is the first study in the English literature that demonstrates the potential protective effect of the stapedial tendon against acoustic damage.

Is there any effect of coenzyme Q10 on prevention of myringosclerosis? Experimental study with rats

Objective

Method

Results

Conclusion

Effect of local use of L-carnitine after myringotomy on myringosclerosis development in rats

OBJECTIVES

This study aimed to investigate the effect of local and intraperitoneal administration of L-carnitine on the prevention of experimentally induced myringosclerosis, and to compare treatment efficiency.

METHODS

Twenty-four Albino-Wistar rats (48 ears) were bilaterally myringotomised and divided randomly into four groups: group one received no treatment, group two received intraperitoneal L-carnitine, group three received local L-carnitine, and group four received both intraperitoneal and local L-carnitine. On the 15th day after treatment, tympanic membranes were harvested and evaluated histopathologically for myringosclerotic plaque formation, fibroblastic proliferation, tympanic membrane thickness and new vessel formation.

RESULTS

The group one tympanic membranes showed extensive thickness, and the incidence of myringosclerosis and fibroblast proliferation were greater than in groups two and four. There were statistically significant differences in tympanic membrane thickness between groups three and four, and in myringosclerosis incidence and fibroblast proliferation, comparing groups two, three and four.

CONCLUSION

Myringosclerosis development was significantly reduced in rats receiving myringotomy plus intraperitoneal L-carnitine. Intraperitoneal L-carnitine administration prevented fibroblastic proliferation and tympanic membrane thickening (both of which cause further tympanic membrane destruction), thus reducing myringotomy-associated morbidity. Local L-carnitine administration had limited effectiveness in this experimental setting.

Matrix metalloproteinase inhibitor attenuates cochlear lateral wall damage induced by intratympanic instillation of endotoxin

OBJECTIVE

Oxytetracycline and ilomastat are inhibitors of matrix metalloproteinases (MMPs). Their efficacy in protecting against cochlear damage induced by the intratympanic instillation of lipopolysaccharide (LPS), as a means of inducing labyrinthitis, was investigated.

MATERIALS AND METHODS

Experiments were performed in 21 young male guinea pigs. Intratympanic instillation of LPS was done in the control group (n=7). Intratympanic instillation of oxytetracycline or ilomastat was done after LPS instillation in the experimental group. Measurements of auditory brainstem response (ABR) and cochlear blood flow (CBF) were performed. The organ of Corti was evaluated by field emission scanning electron microscopy (FE-SEM). The blood-labyrinth barrier (BLB) integrity was evaluated with Evans blue uptake. Gelatin zymography was used to assess the expression of active MMP-2 and MMP-9.

RESULTS

Ears treated with MMP inhibitors were significantly protected from hearing loss compared to the LPS group. In LPS group, there was a significant decrease of CBF. However, experimental group displayed a statistically significant recovery of CBF. FE-SEM revealed hair cell damage in the LPS-treated group, but hair cells presented a normal appearance in MMP inhibitors. The LPS group showed a marked increase of Evans blue extravasation in the cochlea. However, MMP inhibitors significantly reduced the BLB opening. Active MMP-9 was expressed in the LPS group. Treatment with MMP inhibitors attenuated active MMP-9 expression.

CONCLUSION

The MMP inhibitors oxytetracycline and ilomastat protect from cochlear lateral wall damage caused by LPS-induced labyrinthitis.

The preventive effect of N-nitro L-arginine methyl ester in experimentally induced myringosclerosis

OBJECTIVE

The purpose of this study was to investigate the antiinflammatory and antifibrotic effects of N-nitro L-arginine methyl ester (L-name) in experimentally induced myringosclerosis.

METHODS

Twenty Wistar albino rats were bilaterally myringotomized and divided randomly into four groups, each including five rats. Group I received no treatment, Group II was treated with topical saline solution, Group III received topical L-NAME and Group IV received intraperitoneally administered L-NAME. After 2 weeks, the tympanic membranes were examined and scored by otomicroscopy regarding the extent of the myringosclerosis. Then the tympanic membranes were harvested and evaluated histopathologically by light microscopy. The intensity of inflammation and degree of myringosclerosis were evaluated, the mean thickness of tympanic membranes were also measured.

RESULTS

The tympanic membranes of Groups I and II showed extensive myringosclerosis in contrast to those of Groups III and IV which had significantly less or no changes (p < 0.05). The inflammation and fibroblastic activity of the lamina propria in the tympanic membranes of Groups III and IV were found to be significantly less pronounced (p < 0.05). The tympanic membranes were found to be significantly thicker in Groups I and II when compared with Groups III and IV (p < 0.05).

CONCLUSION

Our results showed that both topical and intraperitoneal applications of L-NAME supressed inflammation, reduced fibroblastic proliferation and decreased the formation of myringosclerosis in myringotomized rat tympanic membranes.

Antioxidant effect of pomegranate extract in reducing acute inflammation due to myringotomy

OBJECTIVE

To assess the effect of pomegranate extract on acute inflammation due to myringotomy.

DESIGN

Prospective, randomised study.

SUBJECTS

Thirty Sprague-Dawley rats were divided into three groups. Group one constituted controls. Group two underwent myringotomy. Group three underwent myringotomy and also received 100 µl/day pomegranate extract, via gavage, one day before and two days after surgery. Following sacrifice 48 hours after myringotomy, the animals' right ears were used to determine the concentration of reactive oxygen species, using the chemiluminescence method; left ears were used for histological study.

RESULTS

Reactive oxygen species levels were significantly decreased in group three compared with group two (p < 0.01). The density of inflammatory cells in group three was significantly less than that in group two (p < 0.01). Lamina propria thickness and vessel density were also significantly decreased in group three compared with group two (p < 0.01).

CONCLUSION

Our results indicate that oral pomegranate extract decreases reactive oxygen species concentration and acute inflammation in the tympanic membrane after myringotomy.

Myringosclerosis after tympanostomy tube insertion: relation with tube retention time and gender

OBJECTIVE

To determine relationship between myringosclerosis and tube retention time and sex in children with chronic otitis media with effusion who were treated with tympanostomy tube insertion. Also, the relationship between myringosclerosis both sex and initial age of tube insertion were investigated.

METHODS

A total of 101 children (195 ears) were reviewed. Ears were divided into four groups according to retention time of tympanostomy tubes. Group I: Retention time of tympanostomy tube less than 6 months. Group II: Retention time of tympanostomy tube from 6 months to 12 months. Group III: Retention time of tympanostomy tube of 12 months or more. Group IV: Myringotomy group without tympanostomy tube insertion.

RESULTS

The order of the myringosclerosis rates were as follows from the highest to lowest one; group III (44.1%), group II (42.4%), group I (14.3%), and group IV (7.7%). Myringosclerosis was more common in group I compared with group IV, but the difference was statistically not significant (p>0.05). There were no statistically significant differences in myringosclerosis rates between the group II and group III (p>0.05). On the other hand, statistically significant differences were observed in myringosclerosis rates between group I and group II (p<0.05), and between group I and group III (p<0.05); also similar significant differences were present in myringosclerosis rates between group IV and group II (p<0.05), and between group IV and group III (p<0.05). There was no significant difference between preschool age group and school age group. Myringosclerosis was observed in 40% of boys and in 51.2% of girls.

CONCLUSION

Myringosclerosis is frequent in patients who underwent tympanostomy tube insertion. The frequency of myringosclerosis is much higher in tympanic membranes with tympanostomy tube insertion than tympanic membranes with myringotomy, and the location of sclerotic plaques does not always correspond to the tympanostomy area. The myringosclerosis rate was increased when the tympanostomy tubes stay on tympanic membrane for a long time. Highest myringosclerosis rates were observed if the extrusion time was 12 months or longer. In our analysis, sex and initial age of tube insertion were not significant factors for the development of myringosclerosis after extrusion of tympanostomy tubes.

Ginkgo biloba, a free oxygen radical scavenger, affects inflammatory mediators to diminish the occurrence of experimental myringosclerosis

CONCLUSION

Systemic Ginkgo biloba extract treatment reduces the levels of nitrite/nitrate, malondialdehyde, and superoxide dismutase and increases the levels of glutathione peroxidase. By scavenging free oxygen radicals, ginkgo extract prevents the formation of myringosclerosis.

OBJECTIVE

Our objective was to evaluate inflammatory mediators to determine the antioxidant and anti-inflammatory effect of Ginkgo biloba extract to diminish myringosclerosis.

MATERIALS AND METHODS

Thirty Wistar Albino rats, weighing 320-400 g were used. The upper posterior quadrants of both tympanic membranes were myringotomized and divided into four groups. Ginkgo biloba extract was given orally to groups 1 and 2 comprising eight rats with doses of 100 mg/kg/day and 200 mg/kg/day, respectively. Seven rats in group 3 received 1.5 ml/day saline and seven rats were left untreated. After 10 days of treatment, otomicroscopic evaluation of tympanic membranes and measurement of anti-inflammatory mediators such as superoxide dismutase, nitrite/nitrate, glutathione peroxidase and malondialdehyde were performed.

RESULTS

Myringosclerosis was significantly more severe in control and saline groups than in Ginkgo biloba groups. The levels of nitrite in ginkgo-treated groups were significantly lower than in untreated and saline-treated groups, while glutathione peroxidase levels were significantly higher. The levels of malondialdehyde and superoxide dismutase were lower in ginkgo groups but not significantly.

Evaluation of the polymorphism in the Toll-like receptor 4 (TLR4) genes of tympanosclerosis patients

OBJECTIVE

Although eardrum perforations which endure etiopathogenesis for a long-time and middle ear infections are proposed for causing the tympanosclerosis (TS), tympanosclerosis emerges in some chronic otitis media (COM), some of them do not appear although a continuing COM and enduring perforation last. In this study, the effect of the molecular reasons which display genetic differences in TS formation is evaluated; our aim is to determine the Asp299Gly polymorphism frequencies in the TLR4 gene of patients with TS who have COM, and patients who do not.

MATERIALS AND METHODS

Patients who have undergone COM surgery, were divided into two groups of 50 persons who were selected in accordance with the fact, whether they had TS in their middle ear cavity or not during operation. 100 healthy persons who had similar demographic data, were evaluated as the control group. The DNA isolation was executed by using standard methods with peripheric blood specimen of the diseased group and control group. The Restriction Fragment Length Polymorphism method was used in determining the Asp299Gly allel in the TLR4 gene. Items of 249 bc for the wild tip (Asp) post-restriction enzyme segment wild tip (Asp) allel, and 23 bc and 196 bc post-restriction enzyme segment polymorphic allel (Gly) were obtained.

RESULTS

TLR4 Asp299Gly polymorphism (10%) was asserted in a total of five specimens in the diseased group with TS. TLR4 Asp299Gly polymorphism was found positive in only one (2%) of the 50 phenomenons in the group without TS. TLR4 Asp299Gly polymorphism was found positive in six (6%) of the 100 phenomenons in the control group. The positive polymorphism in phenomenons with TS was significant in accordance with statistics, when compared with the group without TS (p<0.05). However, although the polymorphism rates were higher than the rates of the control group, it was not statistically significant (p>0.05).

CONCLUSION

TS may not appear in many patients who had undergone middle ear infection, and had perforation for many years. The polymorphism in arteriosclerosis in the TLR4 gene which caused the inflammatory cytokines oscillation recognize the bacterial LPS, was also accused. It is engrossing to find out from the results of our study on a restricted number of patients, and on only one gene, that molecular reasons which display genetic differences can also be effective in forming TS. Serial researches of greater dimensions are required.

The preventive effect of ginkgo biloba extract in myringosclerosis: study in rats

OBJECTIVE

To determine the preventive effect of Ginkgo biloba extract in the formation of myringosclerosis.

STUDY DESIGN

Prospective, randomized clinical study.

MATERIALS AND METHODS

Posterosuperior quadrant of tympanic membranes of twenty-five Wistar Albino rats were bilaterally myringotomized. They were divided into three groups randomly. Groups 1 and 2 were administered 100 mg/kg/day and 200 mg/kg/day systemic Ginkgo biloba extract. The third group was treated with 1 mL/day saline solution. After 10 days of treatment, myringotomized membranes were examined by otomicroscopy and harvested. They were evaluated histopathologically by light microscopy and compared according to the occurrence of myringosclerotic plaques and the thickness of membranes.

RESULTS

Tympanic membranes of groups 1 and 2 nearly had no existence of myringosclerosis (72.2% in group 1 and 83.3% in group 2, P = 0.434). However, in group 3, only 14.3 percent had no myringosclerosis (P < 0.001). Thickness of membranes in group 1 was 0.13 +/- 0.25, group 2 was 0.06 +/- 0.02, and group 3 was 0.19 +/- 0.35 mm. Group 3 had significantly thicker membranes compared with groups 1 and 2 (P < 0.001 for group 2 and P = 0.003 for group 1).

CONCLUSION

Formation of experimental myringosclerosis was reduced or inhibited and tympanic membranes were thinner after systemic Ginkgo biloba extract administration.

Does exogenous nitric oxide influence tympanosclerosis? An experimental study

OBJECTIVE

We aimed to elucidate the effects of exogenous nitric oxide application via myrigotomized rat tympanic membranes on tympanosclerosis.

MATERIALS AND METHODS

Forty male rats were included in the study. After myringotomy, nitric oxide was given to the left tympanic cavities and saline was given to the right as the control group. The procedure was repeated 3 times with weekly intervals. Three months after the first procedure, otomicroscopic examination was made and the rats were sacrificed for histologic examination.

RESULTS

Neither otomicroscopic examination, nor histologic examination of middle ears and tympanic membranes revealed any significant difference between the right and left sides. Tympanic membrane thicknesses were also similar on both sides without showing any significant difference.

CONCLUSIONS

Data from this study indicate that exogenous nitric oxide application did not change the occurence of tympanosclerosis in the rat model. Other cytokine interactions are needed to start the reaction sequence leading to tympanosclerosis.

The effect of caffeic acid phenethyl ester on the prevention of experimentally induced myringosclerosis

OBJECTIVES

Myringosclerosis is a common sequela of ventilation tube insertion for the treatment of the otitis media with effusion. Several antioxidants have been identified to prevent myringosclerosis. The objective of this study was to investigate the effect of caffeic acid phenethyl ester (CAPE) on the prevention of experimentally induced myringosclerosis.

METHODS

Thirty-five Sprague-Dawley rats were unilaterally myringotomized. The rats were divided into four groups randomly: group 1 received no treatment, group 2 received intraperitoneally administered saline and group 3 received intraperitoneally administered CAPE. The tympanic membranes were examined by otomicroscopy on the 15th day after treatment. The membranes were then harvested and evaluated histologically by light microscopy.

RESULTS

The tympanic membranes from group 1 showed extensive myringosclerosis; those from group 2 showed a similar occurrence of myringosclerosis. However, group 3 had a reduced occurrence of myringosclerosis by otomicroscopic evaluation. Under light microscopic examination, the lamina propria of the pars tensa was found to be thicker and more sclerotic in groups 1 and 2 when compared with group 3.

CONCLUSIONS

Systemic treatment with CAPE was found to be effective in the prevention of sclerotic lesions in myringotomized rat tympanic membranes.

Evaluation of plasma fibronectine level as a probable indicator for tympanosclerosis

OBJECTIVES

Wound healing, epithelial regrowth and collagen synthesis are very important factors in the repair of the traumatised tympanic membrane. The aim of the present study was to determine the role of plasma fibronectine in the aetiopathogenesis of tympanosclerosis.

METHODS

This prospective study included 58 patients with and 49 without tympanosclerosis. No inflammation or trauma was noted in either patient group. All patients underwent otoscopic and otomicroscopic examination, and the degree of tympanosclerosis was graded from mild (stage I) to severe (stage III). Following otological examination, blood samples were taken for plasma fibronectine measurement.

RESULTS

Following otoscopic and otomicroscopic examinations, patients' tympanosclerosis was graded as follows: 18 patients were stage I; 29 were stage II; and 11 were stage III. Statistical analyses revealed that the plasma fibronectine concentrations were significantly lower in the study group compared with the control group (p = 0.031). In addition, fibronectine levels were lowest in the patients with severest tympanosclerosis (p = 0.0001 in each comparison).

CONCLUSION

The results of the present study show that serum fibronectine is important in the development and severity of tympanosclerosis.

The Anti-Oxidant Effect of Alpha-Tocopherol in the Prevention of Experimentally Induced Myringosclerosis

HYPOTHESIS

The objective of this study was to investigate the possible effect of alpha-tocopherol on the prevention of experimentally induced myringosclerosis.

BACKGROUND

Myringosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion. The relationship between oxygen-derived free radicals and occurrence of myringosclerosis has been proven in experimental models, and it was also shown that the formation of myringosclerosis after experimental myringotomy could be reduced by application of various free radical scavengers.

METHODS

Eighteen Wistar albino rats were myringotomized on the left side and randomly separated into two groups: group A consisted of rats which received intramuscular alpha-tocopherol injections 100 mg/kg daily and group B which were injected with physiological serum only. The occurrence of myringosclerotic plaques in the tympanic membranes of the two groups was compared by otomicroscopy, histopathology, and tympanometry, which is a novel method of quantification. Blood samples were collected for biochemical evaluation, and the tympanic membranes were harvested on the 15th day of the experiment.

RESULTS

In otomicroscopic evaluation, tympanic membranes in group B revealed varying degrees of myringosclerotic plaques; on the other hand, tympanic membranes in group A showed faint or no existence of myringosclerosis. The mean malondialdehyde levels were 1.33 +/- 0.11 micromol/L in group A and 7.49 +/- 1.37 micromol/L in group B (Z = -1.906, p = 0.057). In all ears from group B, the magnitude of the maximum admittance measured by tympanometry reduced to approximately 40% of the values obtained from group A (Z = -2,160, p = 0.031). The mean magnitude of the maximum admittance from group A was very close to the standardization values of Wistar albino rats, which predicts a functional outcome.

CONCLUSION

The formation of myringosclerosis after experimental myringotomy can be diminished by intramuscular alpha-tocopherol injections.

The effect of Vitamin E treatment on the development of myringosclerosis after ventilation tube insertion

OBJECTIVES

Recent studies have established the relationship between the reactive oxygen species and myringosclerosis. Furthermore several antioxidants have been known to prevent myringosclerosis. All the previous studies supporting this hypothesis have been performed on animals. The aim of our study is to investigate the possible effect of Vitamin E on the development of tympanosclerosis after VT insertion on human subjects.

METHODS

72 children undergoing myringotomy and VT insertion were included in the study. Vitamin E was applied to the right ear and no treatment was applied to the left ear. Both ears were examined at the end of 9 months with otomicroscopy. Myringosclerosis formation at the end of the study period was noted for each ear.

RESULTS

Myringosclerosis was found in 33 of the 144 ears. The overall incidence was 22.9%. While 22 (30.6%) of the 72 left ears showed myringosclerosis otomicroscopically, in only 11 (15.3%) of the 72 right ears that were treated with Vitamin E was myringosclerosis observed at the end of the study period. Of these nine cases were bilateral.

CONCLUSION

Animal studies have well documented the development of myringosclerosis after myringotomy and VT insertion and beneficial effects of different antioxidants. Our study has shown similar results in human subjects. Further clinical studies consisting of a larger patient population are needed to bring about routine clinical use of antioxidants in myringotomy and VT insertion.

Tympanometric Changes in an Experimental Myringosclerosis Model After Myringotomy

HYPOTHESIS

The goal of this experimental study was to investigate the specific effect of myringosclerosis on tympanograms in the tympanic membranes of myringotomized rats by using otomicroscopy, tympanometry, and histopathology.

BACKGROUND

Myringosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion. The condition involves the hyalinization and calcification of the collagen layer in certain areas of the tympanic membrane. Previous animal experiments suggest an intimate relationship between the formation of myringosclerosis and an increased oxygen concentration in the environment of the wound after myringotomy. The result of a myringotomy therefore is an increased production of free oxygen radicals, initiating irreversible tissue damage involving fibrosis, hyalin degeneration, and finally apoptosis as observed in myringosclerosis. We propose an experimental model specific for creating sclerotic plaques solely on the tympanic membrane and for performing tympanometric measurements on this pure myringosclerosis model without creating any abnormality in the middle ear to test in what proportion myringosclerosis contributes to decrease of amplitude in tympanograms.

METHODS

To assess the normal tympanometric values of Wistar albino rats, the pressure and peak admittance of the left middle ears were measured using a semiquantitative computerized clinical admittance meter using a sound frequency of 226 Hz. Twelve animals were randomly selected for the myringotomy group and perforations in the left ears were created. All tympanic membrane perforations in this group had healed and closed prior to the otomicroscopic examination and no pathologic reaction was observed in the external ear canals of rats. Otomicroscopic and tympanometric measurements were carried out on Day 15 and the degree of myringosclerosis was noted before the animals were killed. Twelve specimens in the myringotomy group were histopathologically examined for the presence of myringosclerotic plaques.

RESULTS

Under light microscopy, extensive sclerotic lesions were found in the tympanic membranes of the myringotomy group, and these sclerotic deposits were located in the lamina propria. The myringosclerosis occurred predominantly adjacent to the handle of the malleus, but also near the annular region. In all ears with myringosclerosis, the magnitude of the maximum admittance reduced to approximately 50% of the Day-0 values, and this reduction was statistically significant (Z=-3.061, p=0.002).

CONCLUSION

The present findings in this study are consistent with the fact that the movement of the tympanic membrane is hampered by lesions of sclerotic material, resulting in a decrease of amplitude in tympanograms (such as Type As) without any effusion or inflammation in the middle ear.

Otomicroscopic and histologic findings of induced myringosclerosis in rats: a critical study of an experimental model

Myringosclerosis is characterized by hyaline changes of the lamina propria of the tympanic membrane. Experimental studies have used otomicroscopy or histology to evaluate myringosclerosis in animals, but they do not correlate precisely these two methods.

AIM

The present study evaluates the accuracy of otomicroscopy in the diagnosis of myringosclerosis in rats.

STUDY DESIGN

Experimental.

MATERIAL AND METHOD

Myringosclerosis was induced by transtympanic inoculation of Streptococcus pneumoniae in 25 Wistar rats, which were examined weekly through otomicroscopy and sacrificed after eight weeks for histologic study of their tympanic membranes.

RESULTS

From the comparison of the otomicroscopic data in relation to the histologic findings, we could observe sensibility of 80% and specificity of 75% for the otomicroscopy.

CONCLUSION

Considering the results in this study, otomicroscopy did not represent a good method to evaluate myringosclerosis in this experimental model.

Vitamin e-coated tympanostomy tube insertion decreases the quantity of free radicals in tympanic membrane

OBJECTIVE

Tympanosclerosis is a common sequela of ventilation tube treatment of otitis media with effusion causing hearing disability. It is associated with an increased production of free radicals (also known as reactive oxygen species) after myringotomy. Vitamin E is a scavenger of different free radicals by working as an antioxidant. The aim of the present study was to evaluate the effect of vitamin E-coated tympanostomy tube insertion at quantity of free radicals in rat tympanic membrane.

METHODS

This prospective, controlled animal study consisted of male Sprague-Dawley rats divided into two groups of 10 animals each. Ordinary silcone tubes were applied to the right ears of the first group and vitamin E-coated silcone tubes were applied to the right ears of the second group. The left ears were used as controls. Then, the animals were killed and chemiluminescence measurements were made for tympanic membranes.

RESULTS

Reactive oxygen species levels (ROS) were significantly increased in right ears of the first group when compared with the control ears (P < .0001), and the levels were statistically significant decreased in right ears of the second group as compared with the operated ears of the first group (P < .0001). The free radical levels of right and left ears in the second group were similar.

CONCLUSIONS

Our results indicate that vitamin E-coated tube insertion decreases the quantity of reactive oxygen species in tympanic membrane after myringotomy and tympanostomy tube insertion.

Calcium deposition and expression of bone modelling markers in the tympanic membrane following acute otitis media

BACKGROUND AND OBJECTIVES

In accordance with clinical findings, myringosclerosis develops after otitis media (OM) and paracentesis in an experimental setting. The pathogenesis of this phenomenon of calcification is poorly understood. As the calcification process and the sclerotic plaques of the drum mimics features of bone tissue, this study explores tympanic membrane calcium deposition in association with the expression of three bone modelling markers: osteopontin (OPN), osteoprotegerin (OPG) and osteonectin (ON). OPN is secreted by osteoblasts and is found at calcification sites, e.g. during pathological calcification in chronic OM. The cytokine OPG is an inhibitor of bone resorption and consequently bone remodelling. ON is a calcium binding glycoprotein necessary for the maintenance of bone mass and remodelling. It is found in bone matrix and synthesized by osteoblasts.

METHOD

A rat model of acute otitis media (AOM) caused by non-typeable Haemophilus influenzae was used. Four days following middle ear inoculation, a myringotomy was performed in six animals. Another group of ten animals was inoculated only. The drum was dissected in two animals from each group on day 4, 7, 14 and 28 post-inoculation, and the expression of OPN, OPG and ON was determined by immunohistochemistry. von Kossa staining determined the deposition of calcium and immune staining for CD68 identified macrophages.

RESULTS

Calcium depositions were initially accumulated in the cytoplasm of macrophages and dispersed in the connective tissue layers of the pars flaccida and tensa. Late accumulation occurred in the lamina propria of pars tensa, more extensively in myringotomized ears. OPN expression was found early in inflammatory cells including especially macrophages and late in pars tensa fibrocytes. OPG expression was initially located to inflammatory cells and late to pars tensa fibrocytes and the inner basal membrane of pars flaccida. Some ears displayed a marked pars flaccida expression of ON in the connective tissue matrix on early days and at the inner basal membrane on later days. The latter cases were from myringotomized ears. Otherwise, no apparent differences of marker expression occurred between myringotomized and non-myringotomized animals.

CONCLUSION

We conclude that osteopontin, osteoprotegerin and osteonectin are expressed by different cell types in the tympanic membrane during calcification in association with AOM, with or without myringotomy. These molecules may accordingly play a role in the pathogenesis of myringosclerosis, in which macrophages and fibrocytes appear as potential major players.

Achados otomicroscópicos e histológicos da miringoesclerose induzida em ratos: estudo crítico de um modelo experimental

A miringoesclerose é caracterizada por hialinização da lâmina própria da membrana timpânica. Trabalhos experimentais têm utilizado a otomicroscopia ou a histologia para estudar a miringoesclerose em animais, porém sem correlacionar precisamente estes dois métodos de avaliação. OBJETIVO: Este estudo procura avaliar a acurácia da otomicroscopia no diagnóstico de miringoesclerose em modelo experimental com ratos. FORMA DE ESTUDO: experimental. MATERIAL E MÉTODO: Foi induzida miringoesclerose por inoculação transtimpânica de Streptococcus pneumoniae em 25 ratos Wistar, que foram examinados quinzenalmente por otomicroscopia e sacrificados após oito semanas, tendo suas membranas timpânicas examinadas por histologia. RESULTADOS: Da confrontação das alterações otomicroscópicas com os achados histológicos, houve uma sensibilidade de 80% e especificidade de 75%. CONCLUSÃO: Pelos resultados obtidos neste estudo, a otomicroscopia não representou um bom método para avaliar a miringoesclerose neste modelo experimental.

The role of experimental myringosclerosis in interpretation of tympanograms and its possible clinical implications

Myringosclerosis (MS) is hyalinization and calcification of the collagen layer in certain areas of the tympanic membrane (TM) and appears as white chalky patches in otomicroscopy. One of the most common sequela from the use of grommets is the development of MS and its rate in the tubed ear ranges between 44% and 54% during long term follow-up. Among tympanometric configurations, type As tympanograms may indicate ossicular fixation, tympanosclerosis or otitis media with effusion. In case of multiple pathologies (e.g., MS and otitis media with effusion), it is not possible to evaluate the effect of a specific pathology in the absence of other, with otomicroscopy and tympanometry. We believe that the movement of TM is hampered by lesions of sclerotic material, thus resulting in decrease of amplitude in tympanograms without any effusion in middle ear. Now, we propose an experimental model specific for creating MS solely on TM and for performing tympanometric measurements on this pure MS model without creating any pathology in the middle ear, to test in what proportion this specific pathology contributes to decrease of amplitude in tympanograms. A myringotomy in rat's TM admits ambient air into the middle ear cavity, resulting in a relatively hyperoxic condition. The result of a myringotomy therefore is an increased production of free oxygen radicals, initiating irreversible tissue damage involving fibrosis, hyalin degeneration and finally apopitosis as observed in MS. After the closure of perforations, tympanometric measurements can be made on this pure MS model. When evaluating a child for suspected otitis media with effusion, the results of the experimental model might have far-reaching clinical implications and might provide suitable target for prevention of unnecessary myringotomies especially in the pediatric age-group.

Determination of Reactive Oxygen Species in Myringotomized Tympanic Membranes: Effect of Vitamin E Treatment

OBJECTIVES/HYPOTHESIS

Recent studies have established a strong relationship between the development of myringosclerosis and reactive oxygen species (ROS). The aims of the present study were to directly detect ROS in the tympanic membrane and middle ear mucosa of rats by measuring luminol amplified chemiluminescence, to evaluate the changes in the levels of ROS after treatment with vitamin E, and to examine the possible changes in the tympanic membranes otomicroscopically and histologically.

STUDY DESIGN

Prospective controlled animal study.

METHODS

Forty healthy Sprague-Dawley rats were divided into five groups of eight animals each. Animals in all groups except group 1 were bilaterally myringotomized. Group 2 received no treatment, group 3 was treated with topical olive oil, group 4 received topical vitamin E, and group 5 received intramuscular vitamin E. After 24 hours of myringotomy, tympanic membranes were examined otomicroscopically; thereafter, tympanic membranes and middle ear mucosa were peeled off. The right ears of the animals were used for biochemical assay, and the left ears were used for histological study.

RESULTS

Reactive oxygen species levels were significantly decreased in group 4 with topical application of vitamin E compared with untreated and myringotomized animals in group 2. Reactive oxygen species levels were also decreased in group 5, although the decrease was not statistically significant when compared with groups 2 and 3. Histological studies confirmed sclerotic changes in the untreated myringotomized animals. The tympanic membranes of animals in groups 2 and 3 showed a white, chalk-like pattern of sclerotic changes, whereas animals in groups 4 and 5, with the exception of two animals in group 5, lacked these changes.

CONCLUSION

Although the relationship between the development of myringosclerosis and ROS had been well documented previously, the present study is the first that has directly measured the levels of ROS in the tympanic membrane and middle ear mucosa. These results are relevant because they correlate with histological findings. It has also been demonstrated that topically applied vitamin E is effective in decreasing the ROS levels.

The effect of L-carnitine on the prevention of experimentally induced myringosclerosis in rats

The objective of this study was to investigate the possible effect of L-carnitine on the prevention of experimentally induced myringosclerosis. Twenty Sprague-Dawley rats were bilaterally myringotomized. The rats were divided into two groups randomly: group 1 which were intraperitoneally administered saline and group 2 which were intraperitoneally administered L-carnitine. Blood samples were collected for biochemical evaluation and the tympanic membranes were harvested after 28 days. Histopathological and immunohistochemical evaluation were done under light microscopy. The mean malondialdehyde levels were 3.9+/-0.9 in group 2, and 7.9+/-1.1 in group 1 (P<0.001), nitric oxide levels were 25.6+/-6.4 in group 2 and 30.8+/-8.2 in group 1 (P=0.14) and acetylcholinesterase was 1035+/-60 in group 2 and 678+/-35 in group 1 (P=0.001). Myringosclerosis was more frequent and severe in group 1 than group 2 (P<0.007). Immunoreactivity was seen in 16 of 20 tympanic membranes in group 2 and six of 20 tympanic membranes in group 1 (P=0.005). We conclude that L-carnitine diminishes the occurrence of myringosclerosis in rats after myringotomy possibly by antioxidant activity and decreasing the formation of reactive oxygen species.

Surfactant in the middle ear and eustachian tube: a review

There has been a recent surge in research on surfactant and surfactant proteins. Fields ranging from immunology to surface chemistry are making contributions to our understanding of this multifunctional compound. This paper reviews the literature on the structure and function of Eustachian tube surfactant. It covers the proposed functions of endogenous surfactant in normal physiology, as well as the experimental applications of exogenous surfactant in the treatment of otitis media. The analysis is based on four platforms of research: the role of surfactant in the innate immune system, the effect of surfactant on surface tension and Eustachian tube opening pressure, the capacity of surfactant to alter the rheological properties of mucus and the efficiency of the mucociliary system, and the ability of surfactant to mitigate oxygen free radical damage.

Myringotomy delays the tympanic membrane recovery in acute otitis media: a study in the rat model

BACKGROUND/HYPOTHESIS

Acute otitis media is a major cause of visits to pediatric health care providers. Myringotomy in uncomplicated acute otitis media is debatable today. The study addressed this problem through the otomicroscopic and histopathological observations of the events occurring in the tympanic membrane during the first week after myringotomy.

STUDY DESIGN

Randomized study in an experimental animal model.

METHODS

Under anesthesia, the left middle ear of 36 Sprague-Dawley rats was inoculated with Streptococcus pneumoniae type 3. Forty-eight hours later, at day 0, four animals were immediately killed and the remaining animals were randomly assigned into a myringotomy group (n = 16, myringotomy on the left ear) and a non-myringotomy group (n = 16, otomicroscopy without myringotomy). Otomicroscopy and killings were performed in series of four animals from each group at days 1, 2, 4, and 7 after myringotomy. Tympanic membranes were collected after fixation and processed for light and electron microscopy.

RESULTS

All inoculated ears showed a manifest acute otitis media at day 0. An intense infiltration by inflammatory cells and edema distorted severely the tympanic membrane structure. These findings decreased the following days. However, inflammation as evaluated by the thickness and the cytoarchitecture of the tympanic membrane layers, recovered significantly faster in the membranes in the non-myringotomy group. At day 7, all tympanic membranes in the myringotomy group were closed by a hypertrophic keratinizing epithelium and a remodeling connective tissue layer, whereas the animals in the non-myringotomy group had a residual edema in the lamina propria.

CONCLUSIONS

The present infectious model induced an intense inflammatory reaction within the entire structure of the tympanic membrane. Myringotomy provoked a delayed recovery from the inflammatory process within the tympanic membrane. Therefore, if applicable to human conditions, the use of myringotomy in the management of acute otitis media should be restricted to selected cases of acute otitis media.

The inhibitory effect of topical N-acetylcysteine application on myringosclerosis in perforated rat tympanic membrane

OBJECTIVE

Myringosclerosis often occurs in patients in whom ventilation tube insertion and tympanoplasty procedures are performed. Recent studies have revealed a relationship between the development of myringosclerosis and oxygen-derived free radicals, and some investigations have demonstrated that free radical scavengers prevent the development of myringosclerosis. N-acetylcysteine is a well-known anti-oxidant and anti-inflammatory agent. In this study, we aimed to investigate the preventive effect of N-acetylcysteine on myringosclerosis in myringotomized rat tympanic membranes.

METHODS

Twenty Sprague-Dawley rats were bilaterally myringotomized and divided into four groups. Group 1 received no treatment, group 2 was treated with topical saline solution in Spongostan, group 3 received topical 0.6 mg N-acetylcysteine in Spongostan and group 4 received 1.2 mg N-acetylcysteine in Spongostan daily for 12 days. Tympanic membranes were examined by otomicroscopy on day 12. Then, the membranes were harvested and evaluated histologically by light microscopy.

RESULTS

The tympanic membranes of groups 1 and 2 (saline and non-treated) showed extensive occurrence of myringosclerosis, whereas groups 3 and 4 (treated with N-acetylcysteine) showed lesser occurrence of myringosclerosis in otomicroscopic evaluation (P<0.01). Under light microscopic examination, lamina propria of pars tensa was found thicker in groups 3 and 4 when compared with groups 1 and 2. There was no significant difference between groups 3 and 4 (P: 0.30).

CONCLUSIONS

Topically applied N-acetylcysteine was found to be effective in the prevention of sclerotic lesions in myringotomized rat tympanic membranes.

Myringotomized tympanic membranes cultured in vitro do not develop myringosclerosis

The aim of this study was to evaluate the development of myringosclerosis in in vitro-cultured tympanic membranes. Sprague-Dawley rats were myringotomized bilaterally and the tympanic membranes were excised after sacrifice. The explants were placed in inserts in wells filled with a nutrient medium. Every second day the tympanic membranes were photodocumented and after 9 days the explants were prepared for histology. On the 4th day the explants had attached to the bottom of the inserts and the specimens had thickened. From the perforation borders and the dissection edges a thin outgrowth was extending across the surface. By Day 9 the perforation had clearly diminished in size when examined in a stereomicroscope. In a light microscope the keratin layer was seen to protrude towards the centre of the perforation and, at the borders, epithelial cells were bridging the gap. Neither the pars tensa nor the pars flaccida showed any sclerotic lesions. The pars flaccida had thickened and the basal cells of the outer keratinized epithelium had invaded the connective tissue. Inflammatory cells were sparse in both the pars tensa and pars flaccida. The in vitro-cultured myringotomized tympanic membrane therefore shows a similar healing pattern to that in vivo. However, inflammatory reactions are sparse and there is no development of myringosclerosis.

The effect of local administration of N-acetylcysteine in perforated rat tympanic membrane: an experimental study in myringosclerosis

Myringosclerosis (MyS) is a common sequela of acute and chronic otitis media and ventilation tube treatment of serous otitis media. We aimed to study the effect of topical administration of N -acetylcysteine (NAC) on MyS by assessment of otomicroscopic evaluation, lipid peroxidation and nitric oxide (NO) (nitrite/nitrate) levels in experimental myringotomized rat tympanic membrane. Thirty adult rats were used and the upper posterior quadrant of the tympanic membranes of rats was myringotomized. Thereafter, they were divided into four groups. Group I received no treatment, group II was treated with saline, groups III and IV were treated with topical NAC (0.1 ml of 6 and 12 mg ml(-1), respectively). The levels of nitrite/nitrate and malondialdehyde (MDA) were measured in serum samples. In the otomicroscopic evaluation, non-treated and saline treated ears (controls) showed extensive occurrence of myringosclerotic plaques. Groups III and IV showed fewer occurrences of sclerotic plaques. There was no significant difference between groups III and IV regarding the development of MyS. The development of myringosclerotic lesion was found to be significantly different between NAC treated groups (III and IV) and the control groups (I and II). The levels of nitrite/nitrate of both groups III and IV were significantly lower than the control groups. The levels of MDA of these groups were also significantly lower than the control group. The relationship between groups III and IV was not statistically significant for the levels of nitrite/nitrate and MDA. We conclude that the topical treatment of NAC reduces the levels of MDA and NO products in rats. These results suggest that topical NAC application may be useful for the prevention of MyS.

Macrophages and possible osteoclast differentiation in the rat bullar bone during experimental acute otitis media, with reference to tympanosclerosis

HYPOTHESIS

Large osteoclast-like cells, labeled by using monoclonal antibodies directed against macrophages, are participating in a bone remodeling process in the rat bullar bone after induced experimental acute otitis media, leading to tympanosclerosis.

BACKGROUND

In humans, tympanosclerosis is a sequale of chronic otitis media. It causes hearing disability, especially if the ossicles or the inner ear are affected. No successful treatment is available. To evaluate the inflammatory stages that may lead to tympanosclerosis, the current study was performed.

METHODS

Sprague-Dawley rats were exposed to a pneumococcus Type 3 solution into the middle ear. The rats were killed at 3, 6, and 10 days after inoculation. Sections from the ear specimen were stained immunohistochemically. Antibodies used were directed against macrophages.

RESULTS

Positive cells were seen in the tympanic membrane, in the middle ear mucosa, and close to the tympanic membrane insertion into the bone. Macrophages appeared to be linearized adjacent to the bullar bone, both on the inner and on the outer bullar wall. These cells had the appearance of osteoclasts.

CONCLUSION

A differentiation of macrophages to osteoclasts is possible during induced otitis media in the rat, initiating a bone-remodeling process leading to tympanosclerosis.

Topical ascorbic acid reduces myringosclerosis in perforated tympanic membranes. A study in the rat

Myringosclerosis, a common finding after myringotomy, has been recently associated with an increased production of oxygen free radicals. Ascorbic acid's proposed actions include collagen synthesis, antioxidation, and free radical scavenging. The effects of topical ascorbic acid on healing tympanic membranes were studied. Particular attention was given to detecting the presence of myringosclerosis. Twelve Sprague-Dawley rats were bilaterally myringotomized. Their ears were randomized into group A, which received topical ascorbic acid in Gelfoam, group B, which received topical saline solution in Gelfoam, and group C, which received no treatment. The tympanic membranes were harvested on day 13, after routine otomicroscopy. Under light microscopy, the connective tissue layer of the untouched side of the pars tensa was distinctly thicker in group A than in group B or group C. At this level, the extent of sclerotic lesions was significantly less in the ascorbic acid-treated group. It is inferred that topical ascorbic acid reduces the occurrence of myringosclerosis following tympanic membrane perforations in the rat.

Can Eustachian Tube Ventilatory Function Impairment After Oxygen Diving Be Influenced by Application of Free Radical Scavenger Vitamins C and E?

OBJECTIVES/HYPOTHESIS

To evaluate the influence of free radical scavenger vitamins C and E on eustachian tube ventilatory function changes related to oxygen dives.

STUDY DESIGN

Prospective, randomized, double-blind, placebo-controlled study of middle ear impedance changes of oxygen divers being orally treated with free radical scavenger vitamins C and E.

METHODS

Fifteen divers were allocated to two groups. Before diving on oxygen on consecutive days (days 1 and 2), divers in group 1 took a daily dose of 1 g ascorbic acid and 600 International Units d-alpha-tocopherol and divers in group 2 were given placebo. Before diving and 2 and 24 hours after diving on days 1 and 2, middle ear impedance was measured.

RESULTS

Impedance decreased overnight after dive 1 (P =.04) but not after dive 2 (P =.31). No impedance differences were found between groups after the dive on day 1 (P =.83). Twenty-four hours after the dive on day 1 and after the dive on day 2, impedance values in both groups were different (P =.02 vs. P =.07), emphasizing slightly more negative pressures in the vitamin group.

CONCLUSION

Vitamins C and E did not reduce eustachian tube ventilatory function impairment overnight after the dive on day 1, suggesting no evidence of free radical-mediated toxicity affecting the eustachian tube or middle ear mucosa. Repetitive oxygen dives may cause tissue adaptation suggesting other than antioxidant defense mechanisms.