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

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.

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.

Serum myeloperoxidase activity, total antioxidant capacity and nitric oxide levels in patients with chronic otitis media

It has been suggested that oxidative stress may play an important role in the pathogenesis of chronic otitis media (COM), but the role of oxidative stress in the pathogenesis of COM has not yet been fully explored. Therefore, the aim of this study was to investigate serum myeloperoxidase (MPO) activity, 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), total antioxidant capacity (TAC) and nitric oxide (NO) in patients with COM. Sixty-one patients with COM and 30 controls were enrolled in the present study. Patients were divided into two groups according to the presence (n = 21) or absence (n = 40) of cholesteatoma. Serum MPO activity and 4-HNE, MDA and NO levels were significantly higher in patients with COM than controls (for all, p < 0.001), while TAC levels were significantly lower (for all, p < 0.001). Serum MPO activity and MDA, 4-HNE and NO levels were significantly higher in patients with cholesteatoma than in those without cholesteatoma, while TAC levels were significantly lower; but the difference between groups was not statistically significant (p > 0.05). Increased oxidative stress seems to be associated with decreased antioxidant levels in patients with COM. Thus, increased oxidative stress may play a role in the pathogenesis of COM. It is believed that the administration of antioxidant vitamins such as A, C and E may be useful in preventing and treating COM.

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.

The glutathione-S-transferase gene polymorphisms (Gstt1, Gstm1, and Gstp1) in patients with non-allergic nasal polyposis

There is an ongoing dilemma about the pathogenesis of nasal polyp (NP). The etiology of NP is multifactorial. Reactive oxygen species and oxidative stress are also suggested to be among the possible factors in NP development. Glutathione-S-transferase (GST) is one of the important detoxifying enzymes. It is not known whether GST plays any role in NP development. We aimed to investigate the relationship between GST subgroup (GSTT1, GSTM1, and GSTP1) polymorphisms, and NP development. Seventy-five patients with NP with or without asthma (NP with asthma: 22, NP without asthma: 53) were used as a study group. As much as 167 healthy individuals were involved as the control group. NP diagnosis was made by nasal endoscopy and paranasal sinus computed tomography (CT). NP was defined as the presence of endoscopically visible bilateral polyps originated from the middle meatus to the nasal cavity and affecting more than one paranasal sinus confirmed by CT. Blood was collected in EDTA-containing tubes and DNA was extracted from the leukocytes. The genotyping of polymorphisms of GSTT1, GSTM1, and GSTP1 were done using real time polymerase chain reaction. Chi-square (chi(2)) and Fisher's (F) exact tests were used for statistical evaluation. A 2-fold increased risk of NP could be found in individuals with the GSTT1 null genotype (OR = 2.03, 95% CI = 1.03-4.011). The distribution of GSTM1 null genotypes was not significantly different between the NP patients and controls and there was also no significance between the GSTP1 genotypes and NP. In conclusion, GST gene polymorphisms may be important in pathogenesis of NP. Additional studies which include larger study groups in different geographic localizations may be more useful to evaluate association with GST polymorphism and NP.

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.

Lipid peroxidation and some antioxidant enzymes in nasal polyp tissue

Nasal polyp (NP) is considered an inflammatory condition in nasal and paranasal sinus cavities and is frequently encountered in otolaryngology clinics. Although the pathophysiology of nasal polyps is poorly understood, it seems likely that the epithelium may play a critical role in the genesis of inflammatory nasal disease. The aim of this study was to investigate the role of free radicals and antioxidant enzymes in NP and compare these findings with concha bullosa (CB). NP and CB were obtained from 27 and 23 patients, respectively. Glutathione peroxidase (GSH-Px), catalase (CAT), xanthine oxidase (XO) total (enzymic plus non-enzymic) superoxide scavenger activity (TSSA), non-enzymic superoxide scavenger activity (NSSA), superoxide dismutase (SOD), and MDA levels in NP and CB were measured. GSH-Px activiy was significantly lower in patients with NP than in the CB group. However, CAT, XO activities and MDA levels were significantly higher in patients with NP than in the CB group, but TSSA, NSSA and SOD activities were unchanged. Increases in the levels of tissue MDA in patients with NP compared to the CB group may indicate the presence of free radical damage in patients with nasal NP.

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.

Protective effect of L-carnitine on renal ischaemia-reperfusion injury in the rat

This study was designed to investigate the effect of L-carnitine in ischaemia and reperfusion of the rat kidney. Rats were randomly allocated into three groups. Group I (control group; n = 6) received no treatment. Group II (isotonic saline group; n = 6), received 2 ml of isotonic saline 15 min before the renal ischaemia, and group III (carnitine group; n = 6) received L-carnitine hydrochloride (100 mg kg(-1)) intraperitoneally. At the end of the reperfusion period, rats were sacrificed. Tissue malondialdehyde level (MDA), myeloperoxidase (MPO) activity, and nitrite/nitrate (NO) level of renal tissue were measured to evaluate the lipid peroxidation, neutrophil function, and nitric oxide metabolism, respectively. The tissue levels of MDA, MPO and NO were lower in group III (71.8 +/- 8.4, 172.1 +/- 27.4 U g(-1) tissue, 76.3 +/- 29.7 micromol l(-1) respectively) than levels in groups I (103.4 +/- 13.4 nmol g(-1), 325.9 +/- 20.2 U g(-1) tissue, 144.5 +/- 39.2 micromol l(-1), respectively) and II (103.5 +/- 11.4 nmol g(-1), 317.1 +/- 41.5 U g(-1) tissue, 148.9 +/- 23.9 micromol l(-1), respectively). It is shown that carnitine protects kidney tissue against ischaemia-reperfusion injury.

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.