Gi Jung Im

Eugenol: A Phyto-Compound Effective against Methicillin-Resistant and Methicillin-Sensitive Staphylococcus aureus Clinical Strain Biofilms

Background Inhibition and eradication of Staphylococcus aureus biofilms with conventional antibiotic is difficult, and the treatment is further complicated by the rise of antibiotic resistance among staphylococci. Consequently, there is a need for novel antimicrobials that can treat biofilm-related infections and decrease antibiotics burden. Natural compounds such as eugenol with anti-microbial properties are attractive agents that could reduce the use of conventional antibiotics. In this study we evaluated the effect of eugenol on MRSA and MSSA biofilms in vitro and bacterial colonization in vivo. Methods and Results Effect of eugenol on in vitro biofilm and in vivo colonization were studied using microtiter plate assay and otitis media-rat model respectively. The architecture of in vitro biofilms and in vivo colonization of bacteria was viewed with SEM. Real-time RT-PCR was used to study gene expression. Check board method was used to study the synergistic effects of eugenol and carvacrol on established biofilms. Eugenol significantly inhibited biofilms growth of MRSA and MSSA in vitro in a concentration-dependent manner. Eugenol at MIC or 2×MIC effectively eradicated the pre-established biofilms of MRSA and MSSA clinical strains. In vivo, sub-MIC of eugenol significantly decreased 88% S. aureus colonization in rat middle ear. Eugenol was observed to damage the cell-membrane and cause a leakage of the cell contents. At sub-inhibitory concentration, it decreases the expression of biofilm-and enterotoxin-related genes. Eugenol showed a synergistic effect with carvacrol on the eradication of pre-established biofilms. Conclusion/Major Finding This study demonstrated that eugenol exhibits notable activity against MRSA and MSSA clinical strains biofilms. Eugenol inhibited biofilm formation, disrupted the cell-to-cell connections, detached the existing biofilms, and killed the bacteria in biofilms of both MRSA and MSSA with equal effectiveness. Therefore, eugenol may be used to control or eradicate S. aureus biofilm-related infections.

Protective effect of Korean red ginseng extract on cisplatin ototoxicity in HEI-OC1 auditory cells.

Ginseng extract is known to have many beneficial effects, including the reversal of pathological and physiological changes induced by ischemia, stress, and aging. Cisplatin, an effective antineoplastic drug, can cause irreversible sensorineural hearing loss and serious tinnitus in humans; thus cisplatin‐induced ototoxicity is a useful experimental model for ototoxicity. This study investigated the protective effects of Korean red ginseng extract on cisplatin‐induced ototoxicity in auditory cells. Pretreatment with 2.5 mg/mL of ginseng extract prior to application of 20 μm of cisplatin significantly increased cell viability after 48 h of incubation in auditory cells. Pretreatment with ginseng extract significantly attenuated the cisplatin‐induced increase in reactive oxygen species (ROS). Ginseng extract also inhibited the expression of caspase‐3 and poly‐ADP‐ribose polymerase related to cisplatin‐induced apoptosis because a major mechanism of cisplatin‐induced toxicity involves ROS production. Thus, Korean red ginseng extract can play both an anti‐apoptotic and anti‐oxidative role on cisplatin‐induced ototoxicity in an auditory cell line. Copyright

Protective effects of apocynin on cisplatin‐induced ototoxicity in an auditory cell line and in zebrafish

Cisplatin is a very effective anticancer drug and generates reactive oxygen species (ROS) such as superoxide anions that can deplete antioxidant protective molecules in the cochlea. These processes result in the death of cochlear hair cells by induction of apoptosis. Apocynin, which is used as a specific nicotinamide adenine dinucleotide phosphate oxidase inhibitor, has a preventive effect for intracellular ROS generation. In this study, the effect of apocynin was investigated in a cochlear organ of Corti‐derived cell line, HEI‐OC1 cells, and in transgenic zebrafish (Brn3C: EGFP). To investigate the protective effects of apocynin, HEI‐OC1 cells were treated with various concentrations of apocynin and a 20 µm concentration of cisplatin, simultaneously. An in vivo study of transgenic zebrafish (Brn3C: EGFP) was used to investigate the protective effects of apocynin on cisplatin‐induced hair cell death. In an in vitro study, apocynin appeared to protect against cisplatin‐induced apoptotic features on Hoechst 33258 staining in the HEI‐OC1 cells. Treatment of the HEI‐OC1 cells with 100 µm of apocynin, significantly decreased caspase‐3 activity. Treatment of the cells with a 100 µm concentration of apocynin and a 20 µm concentration of cisplatin significantly decreased the intracellular ROS production. In the in vivo study, apocynin significantly decreased the TUNEL reaction and prevented cisplatin‐induced hair cell loss of the neuromasts in the transgenic zebrafish at low concentrations (125 and 250 µm). These findings suggest that apocynin has antioxidative effects and prevents cisplatin‐induced apoptotic cell death in HEI‐OC1 cells as well as in zebrafish. Copyright

Analysis of frequency loss as a prognostic factor in idiopathic sensorineural hearing loss

Abstract Conclusion: The combination of systemic steroids with intratympanic dexamethasone injection (ITDI) did not result in significantly different outcomes from steroid treatment only and did not have any additional beneficial effects. Objective: To evaluate hearing recovery in idiopathic sudden sensorineural hearing loss (ISSNHL) according to frequency and to compare treatment responses between patients treated with systemic steroids and systemic steroids with ITDI. Methods: Ninety-nine patients with ISSNHL were selected to participate in the study by a retrospective medical chart review. Patients were divided into two groups, systemic steroid treatment only and systemic steroid with adjunctive ITDI. Hearing recovery was evaluated by pure tone audiometry (PTA). All patients underwent PTA examination before treatment and after 3 months. Thresholds were analyzed by frequency along with other factors. Results: Low frequency hearing loss responded better than high frequency loss to PTA. When we analyzed pure tone audiogram patterns, all patterns except for the descending type showed better improvement in patients with lower frequency hearing loss than in patients with higher frequency hearing loss.

Differential gene expression profiles in salicylate ototoxicity of the mouse

CONCLUSION This study demonstrated differential gene expression profiles in salicylate ototoxicity with oligonucleotide microarray. This study may also provide basic information on candidate genes associated with hearing loss and/or tinnitus or recovery after salicylate-induced cochlear dysfunction. OBJECTIVES Salicylate ototoxicity is accompanied by temporary hearing loss and tinnitus. The purpose of the present study was to evaluate the gene expression profiles in the mouse cochlea with salicylate ototoxicity using DNA microarray. MATERIALS AND METHODS The subject mice were injected intraperitoneally with 400 mg/kg of sodium salicylate; an approximate 30 dB threshold shift that was observed by auditory brainstem response was achieved 3 h after an injection of sodium salicylate and the hearing threshold returned to within normal range at 3 days. Differential gene expression profiles at 3 h after salicylate injection in comparison to the normal cochlea were analyzed with DNA microarray technology. RESULTS No ultrastructural changes in the mice cochlea were observed by TEM at 3 h after salicylate injection. Microarray revealed that 87 genes were up-regulated twofold or more in the mouse cochlea with salicylate ototoxicity in comparison to the normal cochlea. Among these genes, increased expression levels of 30 functional genes were confirmed by semi-quantitative RT-PCR.Conclusion. This study demonstrated differential gene expression profiles in salicylate ototoxicity with oligonucleotide microarray. This study may also provide basic information on candidate genes associated with hearing loss and/or tinnitus or recovery after salicylate-induced cochlear dysfunction. Objectives: Salicylate ototoxicity is accompanied by temporary hearing loss and tinnitus. The purpose of the present study was to evaluate the gene expression profiles in the mouse cochlea with salicylate ototoxicity using DNA microarray. Materials and methods: The subject mice were injected intraperitoneally with 400 mg/kg of sodium salicylate; an approximate 30 dB threshold shift that was observed by auditory brainstem response was achieved 3 h after an injection of sodium salicylate and the hearing threshold returned to within normal range at 3 days. Differential gene expression profiles at 3 h after salicylate injection in comparison to the normal cochlea were analyzed with DNA microarray technology. Results: No ultrastructural changes in the mice cochlea were observed by TEM at 3 h after salicylate injection. Microarray revealed that 87 genes were up-regulated twofold or more in the mouse cochlea with salicylate ototoxicity in comparison to the normal cochlea. Among these genes, increased expression levels of 30 functional genes were confirmed by semi-quantitative RT-PCR.

Protective effects of edaravone against cisplatin-induced hair cell damage in zebrafish

OBJECTIVE Edaravone is known to have a potent free radical scavenging effect. The objective of the present study was to evaluate the effects of edaravone on cisplatin-induced ototoxicity in transgenic zebrafish (Brn3C: EGFP). METHODS Five day post-fertilization zebrafish larvae were exposed to 1000 μM cisplatin and 50 μM, 100 μM, 250 μM, 500 μM, 750 μM, and 1000 μM concentrations of edaravone for 4h. Hair cells within neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed by fluorescence microscopy and confocal microscopy (n=10). Hair cell survival was calculated as a percentage of the hair cells in the control group that were not exposed to cisplatin. Ultrastructural changes were evaluated using scanning electron microscopy and transmission electron microscopy. RESULTS Edaravone protected cisplatin-induced hair cell loss of neuromasts (edaravone 750 μM: 8.7 ± 1.5 cells, cisplatin 1000 μM only: 3.7 ± 0.9 cells; n=10, p<0.0001) and decreased the Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) reaction. Structures of mitochondria and hair cell within neuromasts in ultrastructural analysis were preserved in zebrafish exposed to 1000 μM cisplatin and 750 μM edaravone for 4h. CONCLUSIONS Edaravone attenuated cisplatin-induced hair cell damage in zebrafish. The results of the current study suggest that cisplatin induces apoptosis, and the apoptotic cell death can be prevented by treatment with edaravone in zebrafish.

Protective effects of caffeic acid phenethyl ester (CAPE) against neomycin-induced hair cell damage in zebrafish

OBJECTIVE Caffeic acid phenethyl ester (CAPE) is known to reduce the generation of oxygen-derived free radicals, which is a major mechanism of aminoglycoside-induced ototoxicity. The objective of the present study was to evaluate the effects of CAPE on neomycin-induced ototoxicity in zebrafish (Brn3c: EGFP). METHODS Five-day post-fertilization zebrafish larvae (n=10) were exposed to 125 μM neomycin and one of the following CAPE concentrations for 1h: 50, 100, 250, 500, or 1000 μM. Ultrastructural changes were evaluated using scanning electron microscopy (SEM). The terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) assay and 2-[4-(dimethylamino)styryl]-N-ethylpyridiniumiodide (DASPEI) assay were performed for evaluation of apoptosis and mitochondrial damage. RESULTS CAPE decreased neomycin-induced hair cell loss in the neuromasts (500 μM CAPE: 12.7 ± 1.1 cells, 125 μM neomycin only: 6.3 ± 1.1 cells; n = 10, P < 0.05). In the ultrastructural analysis, structures of mitochondria and hair cells were preserved when exposed to 125 μM neomycin and 500 μM CAPE. CAPE decreased apoptosis and mitochondrial damage. CONCLUSION In the present study, CAPE attenuated neomycin-induced hair cell damage in zebrafish. The results of the current study suggest that neomycin induces apoptosis, and the apoptotic cell death can be prevented by treatment with CAPE in zebrafish.

Nasopharynx as a microbiologic reservoir in chronic suppurative otitis media: preliminary study.

Objectives The present study was designed to identify the correlations of bacterial strains of the middle ear and the nasopharynx in chronic suppurative otitis media (CSOM) patients who were scheduled for operations. Methods Sixty-three patients with CSOM were enrolled in the study. Culture specimens were collected from the middle ear and nasopharynx of patients who were admitted for operation. Samples collections were performed 3 times; from the middle ear and nasophaynx at the admission day, from the middle ear during the operation, and from the external auditory canal post-operatively. Bacteria were identified by gram staining and biochemical tests. The correspondence rate of organisms which simultaneously exist in the middle ear and the nasopharynx was measured. Results Sixty-eight organisms were isolated from the middle ear and 57 organisms from the nasopharynx among 63 patients. Of 68 bacteria identified in middle ear, 26.52% (18 bacteria) corresponded with those of nasopharynx. MRSA had the high correspondence rate, and of 18 methicillin-resistant Staphylococcus aureus (MRSA) isolated from middle ear, 33.3% (6 bacteria) corresponded with nasophaynx. Meanwhile, 3 organisms of MRSA were detected from the external auditory canal post-operatively, although they were only found in nasopharynx pre-operatively. Conclusion The current trend of middle ear swab alone for bacterial detection would be insufficient to identify the potent MRSA and impede early antibiotic intervention for the effective middle ear surgery. Therefore, it is necessary to perform nasopharynx cultures together with conventional middle ear culture to control potent risk for infection pre-operatively.

Protective Role of Trimetazidine Against Neomycin-induced Hair Cell Damage in Zebrafish

Objectives Trimetazidine (TMZ) is known to reduce the generation of oxygen-derived free radicals. The objective of the present study was to evaluate the effects of TMZ on neomycin-induced ototoxicity in transgenic zebrafish (Brn3C: EGFP). Methods Five-day, postfertilization zebrafish larvae were exposed to 125 µM neomycin and one of the following TMZ concentrations for 1 hour: 10 µM, 100 µM, 500 µM, 1,000 µM, 1,500 µM, or 2,000 µM. Hair cells within the neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed using fluorescence microscopy and confocal microscopy (n=10). Hair cell survival was calculated as a percentage of hair cells in the control group that were not exposed to neomycin. Ultrastructural changes were evaluated using scanning electron microscopy. Results TMZ protected against neomycin-induced hair cell loss in the neuromasts (TMZ 1,000 µM, 11.2±0.4 cells; 125 µM neomycin only, 4.2±0.5 cells; n=10; P<0.05) and decreased the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) reaction. In the ultrastructural analysis, structures of mitochondria and hair cells within the neuromasts were preserved in zebrafish exposed to 125 µM neomycin and 1,000 µM TMZ. Conclusion TMZ attenuated neomycin-induced hair cell loss in zebrafish. The results of this study suggest that neomycin induces apoptosis, and that apoptotic cell death can be prevented by treatment with tremetazidine.

Expression of β-defensins in the tubotympanum of experimental otitis media

Conclusion. Since the expression levels of β-defensins 2–4 were up-regulated in experimental otitis media, they may play a protective role in the pathogenesis of otitis media. Objectives. Defensins are antimicrobial peptides that play a major role in innate immunity. The goal of this study was to identify the expression of defensins in experimental otitis media of the mouse. Materials and methods. The expression of three α-defensins (cryptdins, cryptdin-related sequences 1-C (CRS1-C), and CRS4-C) and four β-defensins (mBD1, mBD2, mBD3, and mBD4) was investigated in the tubotympanum of experimental otitis media in mice by a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR), and the expression levels of three β-defensins (mBD2, mBD3, mBD4) were evaluated by Western blotting. Results. The α-defensins were not expressed in the tubotympanum. mBD1 was expressed constitutively in normal middle ear mucosa and Eustachian tube mucosa, but up-regulated expression of mBD2, mBD3, and mBD4 was observed with RT-PCR and Western blotting in the tubotympanums in experimental otitis media, while the normal tubotympanums did not express them.