Effect of Ginkgo biloba extract on endotoxin-induced labyrinthitis.

OBJECTIVE: There are no reports on the therapeutic effect of Ginkgo biloba extract (GBE) on otitis media-induced labyrinthitis. The present study examined whether GBE can protect against cochlear damage induced by intratympanic instillation of lipopolysaccharide (LPS)-induced labyrinthitis. MATERIALS AND METHODS: Experiments were performed in 20 healthy young male guinea pigs. The control group (n=10) received an intratympanic instillation of LPS (20 µl, 3mg/ml). The experimental group (n=10) received intratympanic instillation of LPS immediately after instillation of GBE (10mg/kg) and then experimental groups received GBE (100mg/kg) by intraperitoneal injection every day for 3 days. Instillation of LPS or LPS immediately after GBE was done in the right ear; the untreated left ear was considered normal. Physiological and morphological changes were evaluated. RESULTS: Statistical analysis of treatment of GBE revealed significantly less hearing loss than LPS group (p<0.05). The ratio of the value of cochlear blood flow (CBF) compared to untreated left side was significantly higher in the GBE treated group than in the LPS-treated group (p<0.05). This result indicated the recovery of CBF in GBE treated group compared to LPS treated group. In the LPS group, scanning electron microscopy revealed hair cell damage with edema. Missing stereocilia in the third layer of the outer hair cell was revealed. However, both the inner hair cells and the outer hair cells had normal appearance in the GBE group. LPS group showed that cochlear Evans blue extravasation was increased strongly in the stria vascularis, spiral limbus, and in the spiral ligament compared with the GBE treated group. CONCLUSION: GBE significantly minimizes cochlear damage against LPS-induced otitis media with labyrinthitis in a guinea pig model. GBE has potential as an adjunctive therapy to antibiotics in the treatment of acute otitis media with complicated labyrinthitis.

Effect of piperacillin-tazobactam coated ß-tricalcium phosphate for mastoid obliteration in otitis media.

BACKGROUND AND OBJECTIVE: ß-Tricalcium phosphate (TCP) has good biodegradability and osteoconductivity as a scaffold material for bone tissue engineering. Both block and granular forms are available; however, it has been associated with risk of infection and exposure. To this end, the study evaluated the effect of piperacillin-tazobactam coated ß-TCPs for mastoid obliteration in otitis media. MATERIALS AND METHODS: Ten guinea pigs were divided into the experimental (piperacillin-tazobactam coated ß-TCP granules, n=5) and control groups (uncoated ß-TCP granules, n=5). After mastoid obliteration, transtympanic injection with a saline suspension of lipopolysaccharide established inflammation. The animals were sacrificed 5 weeks later. Tissue sections were stained with hematoxylin and eosin and examined. RESULTS: Encapsulation and formation of fibrous capsule by foreign material in the bulla were not evident. The histological evaluation did not reveal inflammatory cells and fibrosis in the piperacillin-tazobactam coated ß-TCP group. In contrast, the control group showed numerous inflammatory cells around the implanted uncoated ß-TCP granules and incomplete new bone formation. CONCLUSION: ß-TCP is an effective carrier material for piperacillin-tazobactam. The use of piperacillin-tazobactam coated ß-TCP may be optimal for mastoid obliteration.

Effect of nebulized bovine surfactant for experimental otitis media with effusion.

OBJECTIVES: In this study, we evaluated the efficacy of nebulized bovine pulmonary surfactant on experimentally induced otitis media with effusion (OME) in guinea pigs. METHODS: Twenty guinea pigs were divided into three groups. Four untreated animals served as normal controls. Experimental OME was established in both ears of the remaining 16 animals by a transbullar injection of 10 microL of Pseudomonas aeruginosa lipopolysaccharide in saline. Thereafter, the guinea pigs received nebulized phosphate buffered saline (n=8) or nebulized bovine pulmonary surfactant (n=8). Nebulization was given daily for 7 days. On day 8, all the animals' passive opening pressure (POP) of the Eustachian tube was measured and histopathological observations of the bulla were made by light microscopy. RESULTS: Nebulized bovine pulmonary surfactant significantly reduced the POP compared to that of saline nebulization. The bovine pulmonary surfactant improved the tubal patency and produced less histopathologcally-evident edematous bullar mucosa. CONCLUSION: Nebulization of bovine pulmonary surfactant plays an important role in treating otitis media with effusion in guinea pigs. Our results suggest that the chosen nebulized bovine pulmonary surfactant can be of good clinical benefit for treating OME in the future.

Efficacy of transnasal nebulized surfactant on experimental otitis media with effusion in guinea pig.

OBJECTIVE: Recently experimental trials have demonstrated that nebulized natural surfactant is effective in the treatment of experimental otitis media with effusion (OME). Two methodologically incomplete studies using animal models of induced OME have reported that nebulized surfactant can improve Eustachian tube function. There have been no reports that investigated the efficacy of the nebulized surfactant for OME using analysis of tympanic membrane vibration. In this study, we evaluated the therapeutic effect of nebulized natural surfactant by investigation of tympanic membrane vibration. MATERIALS AND METHODS: The guinea pigs (n=20) were divided into three groups. Four normal guinea pigs without any treatment were used as normal controls. Sixteen pigs were given experimental OME in both ear and then divided into two groups. The OME model of guinea pig was created by transbullar injection 10 microl of lipopolysaccharide in saline. Experimental group 1 (n=8) was nebulized phosphate buffered saline (PBS). Experimental group 2 (n=8) was nebulized natural bovine surfactant. The transnasal nebulization was repeated for 7 days in both experimental groups. On the 8th day, both experimental groups and normal control group were measured the tympanic membrane vibration by laser Doppler vibrometer (LDV), and additionally histopathologic observation was performed by scanning electron microscope (SEM). RESULTS: The TM vibration velocity in nebulized PBS group showed significantly reduced mainly at low frequencies. However, nebulized natural surfactant group recovered the reduction of tympanic membrane vibration. In nebulized PBS group, SEM showed severe thickened subepithelial layer and hyperplasia of gland structure. However, in nebulized natural surfactant group, SEM showed the reduced the thickness of subepithelial layer and the loss of glandular hyperplasia. CONCLUSION: From our results, the nebulized natural surfactant is postulated to be effective in the treatment of intractable OME in animal model. The measurement of tympanic membrane vibration for analysis of middle ear mechanics was significantly corresponding to the middle ear mucosal changes. LDV is a useful tool for investigate the therapeutic effect of nebulized surfactant in experimental OME. With supporting clinical studies, nebulization of natural surfactant may become noninvasive treatment of OME in future.

Antibacterial effect of octylcyanoacrylate against ciprofloxacin-resistant Pseudomonas aeruginosa isolates from patients with chronic suppurative otitis media.

BACKGROUND: There has been a steady increase in the number of cases of ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) otorrhea; this is a growing medical concern. For otological surgery in children, octylcyanoacrylate can be an alternative method of closure for surgical incisions. Recent in vitro studies have shown that octylcyanoacrylate is effective as an antimicrobical barrier. To date, there have been only rare reports on the antibacterial effect of octylcyanoacrylate against CRPA. The purpose of this study is to determine the antimicrobial effects of octyl-cyanoacrylate against the CRPA that was isolated from patients with chronic suppurative otitis media. PATIENTS AND METHODS: Clinical CRPA (n=20) bacteria and ciprofloxacin-sensitive PA (CSPA) (n=20) were obtained from patients. The susceptibilities to various antibiotics were determined by disk diffusion method. RESULT: Both CSPA and CRPA were resistant to octylcyanoacrylate. CONCLUSION: Results demonstrated that octylcyanoacrylate has no antibacterial activity against CSPA and CRPA.

The effect of increased inner ear pressure on tympanic membrane vibration.

BACKGROUND & OBJECTIVE: It has been suggested that increased inner ear pressure can affect the stiffness of the tympano-ossicular conductive system. However, the published literature contains few studies on changes of middle ear mechanics caused by increased inner ear pressure. In this study, we evaluated the effects of increased inner ear pressure on tympanic membrane vibration in guinea pigs using a laser Doppler vibrometer (LDV). MATERIALS AND METHODS: We used 10 male guinea pigs (weighing 250 g each) with normal eardrums and Preyer reflexes were used for the experiment. Inner ear pressure was modified by two approaches--directly via a tube placed in the inner ear (n=5) and indirectly via a tube placed in the subaracnoid space (n=5). Slow uniform pressure (microl/min) was infused until constant pressure was maintained. At this time, an artificial endolymph or perilymph was injected with a constant pressure of 100 and 300 mm H2O. We measured the umbo velocity using a LDV. RESULTS: A positive pressure load decreased the umbo vibration at low frequencies but did not change the umbo vibration at mid and high frequencies. The umbo velocity had a greater reduction for an endolymphatic pressure load than for a perilymphatic pressure load. The largest change in velocity was noted at a frequency of 0.1 kHz. There was no significant change in velocity at higher frequencies, except for 5 kHz. CONCLUSION: LDV is a good tool to analyze middle ear function and it has the potential indirectly to diagnose an increase in endolymphatic or perilymphatic pressure.

The use of piperacillin-tazobactam coated tympanostomy tubes against ciprofloxacin-resistant Pseudomonas biofilm formation: an in vitro study.

BACKGROUND AND OBJECTIVE: Bacterial biofilm formation has been implicated in the high rate of persistent otorrhea after tympanostomy tube insertion. It has been suggested that the tube material may be an important factor in the development of otorrhea. Recently we reported the presence of ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) biofilms on infected tympanostomy tubes following the use of intractable post-tympanostomy tubes and the onset of otorrhea. In this study, we have evaluated the resistance of piperacillin-tazobactam coated with chitosan on a tympanostomy tube to prevent CRPA biofilm formation in vitro. MATERIALS AND METHODS: Three sets each of piperacillin-tazobactam coated silicone tubes (n=5), commercial silver-oxide coated silicone tubes (Activent, Silic) (n=5) and control uncoated tympanostomy tubes (Paparella type 1) (n=5) were processed for evaluation. The piperacillin-tazobactam coated tympanostomy tubes were compared with the silver-oxide coated tubes and the uncoated control tubes for resistance to CRPA biofilm formation after in vitro incubation. RESULTS: Scanning electron microscopy showed that the surface of the silver-oxide coated tube (Activent) formed a thick biofilm with crusts as well as an uncoated tube. In contrast, the surface of a piperacillin-tazobactam coated tympanostomy tube showed virtually no CRPA biofilm formation. CONCLUSION: The piperacillin-tazobactam coated tympanostomy tube showed resistance to CRPA biofilm formation. The piperacillin-tazobactam coating may be useful to reduce CRPA biofilm formation; however, further in vivo studies are necessary.

Evaluating the ototoxicity of topical piperacillin-tazobactam.

BACKGROUND AND OBJECTIVE: With the increased use of ototopical ciprofloxacin solution, newly evolved bacterial fluoroquinolone resistance has also become more of a problem. The emergence of ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) has created a new therapeutic challenge in otology. We evaluated the ototoxicity of topical fortified piperacillin-tazobactam solution by performing experiments in young male albino guinea pigs (weight, 250-300 g each). MATERIALS AND METHODS: Antimicrobial assay by direct contact test using scanning electron microscope was performed. Twenty guinea pigs (250-300 g) were treated with fortified piperacillin-tazobactam solution. In experimental group 1 (n=10), a gelfoam ball impregnated with 120 microl of fortified piperacillin-tazobactam was implanted on the round window membrane by a posterior approach. In experimental group 2 (n=10), 20 microl of fortified piperacillin-tazobactam was injected into the middle ear cavity via silicone tube with a small hole placed in the superior aspect of the bulla by drilling. The drug application through the tube was performed for 7 consecutive days. In control group (n=5), a gelfoam ball impregnated with 120 microl of gentamicin solution (80 mg/2 ml) was implanted on the round window membrane. RESULTS: The fortified piperacillin-tazobactam 20 microl treated CRPAs showed destruction of their cell membrane in antimicrobial assay by direct contact test. No significant difference in the mean auditory brainstem response (ABR) thresholds before and after drug administration was found for the experimental group. However, significant elevation of the mean ABR thresholds was found for the control group. In experimental group, scanning electron microscopy showed almost normal sterociliary arrangements and surface structure on the inner and outer hair cells. However, significant destruction of outer hair cells was identified in control group. CONCLUSION: This present study's data suggests that fortified piperacillin-tazobactam solution can be effectively used for topically treating CRPA otorrhea in those patients who suffer with chronic suppurative otitis media.

The effect of anti-adhesive packing agents in the middle ear of guinea pig.

BACKGROUND & OBJECTIVE: The presence of adhesions after middle ear surgery is not uncommon. Fibrosis can cause conductive hearing loss and it contributes to retraction of the tympanic membrane in the post-surgery patient. The purpose of this study was to evaluate the anti-adhesive effect of Seprafilm and MeroGel in the abraded mucosa of a guinea pig's middle ear. MATERIALS AND METHODS: Fifteen pathogen-free adult male albino guinea pigs weighing 250-300g each were used. Under an aseptic condition, the middle ear mucosa was abraded using a pick through a myringotomy incision. Seprafilm, MeroGel and Gelfoam, respectively, were then packed into guinea pigs' middle ear cavities. Auditory brainstem responses (ABRs) were assessed preoperatively and 3 weeks after operation. RESULTS: The ABR results at postoperative week 3 showed no statistically significant difference for the myringotomy and postpacking, except for the MeroGel packing. However, there was no significant threshold on the 6 weeks' postoperative ABR. The Gelfoam group demonstrated extensive fibrosis and adhesion within the bulla cavity. The Seprafilm and MeroGel groups showed no adhesion in the middle ear cleft after abrasion of the mucosa. CONCLUSION: From these results, we suggest the use of Seprafilm and MeroGel to improve the results of otosurgery.

Mastoid obliteration using a hyaluronic acid gel to deliver a mesenchymal stem cells-loaded demineralized bone matrix: an experimental study.

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate whether a combination of expanded human mesenchymal stem cells (hMSCs) with hyaluronic acid gel in human demineralized bone matrix (hDBM) can promote osteogenesis in a mastoid obliteration procedure, with using the guinea pig as an animal model. MATERIALS AND METHODS: Fourteen male guinea pigs were used for the experiment. Bulla obliteration using 6-diamidino-2-phenylindole (DAPI)-labeled hMSCs (2x10(6)) loaded into hDBM with hyaluronic acid hydrogel was performed in the experimental group (n=7). The control group was obliterated using hDBM only (n=7). The histologic findings and microCT images were obtained from each bulla at 3 and 7 weeks postsurgery. RESULTS: The increased soft tissue intensity caused by chondrogenic differentiation around the implanted hMSCs-loaded hDBM was identified, as compared to the hMSCs-free hDBM group. All the hMSCs-loaded hDBM at 7 weeks post-implantation displayed greater amounts of bone filling the bulla space, as compared to the hMSCs-free hDBM implanted group. In the hMSCs-free hDBM group, microCT shows incomplete new bone formation, as compared to the hyaluronic acid gel-hMSCs treated group. CONCLUSION: The successful formation of bone using allogeneic hMSCs loaded onto hDBM and hyaluronic acid hydrogel to repair critically sized bulla defects in the guinea pig model was accompanied with the absence of any local response to the foreign cells. The use of hMSCs-loaded hDBM and hyaluronic acid hydrogel is appropriate for performing clinical mastoid obliteration.

The effect of Interceed for reducing adhesion as a middle ear packing agent: an experimental study.

BACKGROUND AND OBJECTIVE: Interceed (oxidized regenerated cellulose) has been used to prevent postoperative abdominal adhesion. However, the efficacy and safety of using Interceed in middle ear surgery have not been thoroughly studied. MATERIALS AND METHODS: The animals were divided into two groups: the Interceed group and the Gelfoam (Gelatin sponge) group. In every group, the study was performed on five guinea pigs (ten ears). Under the aseptic condition, the middle ear mucosa was abraded using a pick through a myringotomy incision. Interceed and Gelfoam were then packed into the guinea pigs' middle ear cavities. The auditory brainstem responses (ABRs) were assessed preoperatively and at 3 weeks after the operation with the animals under general anesthesia. Histopathologic study was performed 3 weeks after the operation. RESULTS: The ABR results on postoperative week 3 showed no statistically significant difference for myringotomy and postpacking. The fibrosis, middle ear mucosa thickening and adhesion formation appeared to be less in the Interceed group compared with the Gelfoam group. Any foreign body reaction was not observed in the Interceed group. CONCLUSION: Our results show that Interceed is nonototoxic and biocompatible with the guinea pig's middle ear cavity. Therefore, these results suggest that Interceed could be used safely in the middle ear as a middle ear packing agent during otosurgery.

Antibacterial effect of octylcyanoacrylate against methicillin-resistant Staphylococcus aureus isolates from patients with chronic suppurative otitis media.

UNLABELLED: There has been a steady increase in the number of cases of methicillin-resistant Staphylococcus aureus (MRSA) otorrhea; this is a growing medical concern. For otological surgery in children, octylcyanoacrylate can be an alternative method of closure for surgical incisions. Recent in vitro studies have shown that octylcyanoacrylate is effective as an antimicrobical barrier. To date, there have been only rare reports on the antibacterial effect of octylcyanoacrylate against MRSA. The purpose of this study is to determine the antimicrobial effects of octylcyanoacrylate against the MRSA that was isolated from patients with chronic suppurative otitis media. MATERIALS AND METHODS: Clinical MRSA (n=20) bacteria and methicillin-sensitive SA (MSSA) (n=20) were obtained from patients. The susceptibilities to various antibiotics were determined by disk diffusion method. RESULTS: MSSA was sensitive to octylcyanoacrylate. The antibacterial activity of octylcyanoacrylate was weak against MRSA. CONCLUSION: Our results demonstrated that octylcyanoacrylate has slight antibacterial activity against MRSA.

Structure-activity relationship of HP (2-20) analog peptide: enhanced antimicrobial activity by N-terminal random coil region deletion.

HP (2-20) (AKKVFKRLEKLFSKIQNDK) is a 19-aa antimicrobial peptide derived from N-terminus of Helicobacter pylori Ribosomal protein L1 (RpL1). In the previous study, several analogs with amino acid substitutions were designed to increase or decrease only the net hydrophobicity. In particular, substitutions of Gln(16) and Asp(18) with Trp (Anal 3) for hydrophobic amino acid caused a dramatic increase in antibiotic activity without a hemolytic effect. HP-A3 is a potent antimicrobial peptide that forms, in a hydrophobic medium, an amphipathic structure consisting of an N-terminal random coil region (residues 2-5) and extended C-terminal regular alpha-helical region (residues 6-20). To obtain the short and potent alpha-helical antimicrobial peptide, we synthesized a N-terminal random coil deleted HP-A3 (A3-NT) and examined their antimicrobial activity and mechanism of action. The resulting 15mer peptide showed increased antibacterial and antifungal activity to 2- and 4-fold, respectively, without hemolysis. Confocal fluorescence microscopy studies showed that A3-NT was accumulated in the plasma membrane. Flow cytometric analysis revealed that A3-NT acted in salt- and energy-independent manner. Furthermore, A3-NT causes significant morphological alterations of the bacterial surfaces as shown by scanning electron microscopy. Circular dichroism (CD) analysis revealed that A3-NT showed higher alpha-helical contents than the HP-A3 peptide in 50% TFE solution. Therefore, the cell-lytic efficiency of HP-A3, which depended on the alpha-helical content of peptide, correlated linearly with their antimicrobial potency.

Antibacterial effect of tea-tree oil on methicillin-resistant Staphylococcus aureus biofilm formation of the tympanostomy tube: an in vitro study.

UNLABELLED: The antibacterial effects of tea-tree oil against the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilm on the surface of the tympanostomy tubes was evaluated. MATERIALS AND METHODS: Silicone tympanostomy tubes were pretreated with normal saline for 12 hours, the control group (n=4), with 100% tea-tree oil, experimental group A (n=3), or with 50% tea-tree oil, experimental group B (n=3). All the tubes were incubated in a MRSA solution for 2 days and then processed for evaluation using scanning electron microscopy. RESULTS: The development of the biofilm mode of growth of MRSA was observed in the saline-treated control group. In contrast, only focal biofilms were present on the tube surface in experimental group A and considerable reduction of biofilm with destruction of the MRSA cells was shown in experimental group B. CONCLUSION: From these results, the antimicrobial effect of tea-tree oil against biofilm formation on tympanostomy tubes in vitro has been verified.