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Towers ER, Kelly JJ, Sud R, Gale JE, Dawson SJ. Caprin-1 is a target of the deafness gene Pou4f3 and is recruited to stress granules in cochlear hair cells in response to ototoxic damage. J Cell Sci 2011; 124:1145-55. [PMID: 21402877 DOI: 10.1242/jcs.076141] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The POU4 family of transcription factors are required for survival of specific cell types in different sensory systems. Pou4f3 is essential for the survival of auditory sensory hair cells and several mutations in human POU4F3 cause hearing loss. Thus, genes regulated by Pou4f3 are likely to be essential for hair cell survival. We performed a subtractive hybridisation screen in an inner-ear-derived cell line to find genes with differential expression in response to changes in Pou4f3 levels. The screen identified the stress-granule-associated protein Caprin-1 as being downregulated by Pou4f3. We demonstrated that this regulation occurs through the direct interaction of Pou4f3 with binding sites in the Caprin-1 5' flanking sequence, and describe the expression pattern of Caprin-1 mRNA and protein in the cochlea. Moreover, we found Caprin-1-containing stress granules are induced in cochlear hair cells following aminoglycoside-induced damage. This is the first report of stress granule formation in mammalian hair cells and suggests that the formation of Caprin-1-containing stress granules is a key damage response to a clinically relevant ototoxic agent. Our results have implications for the understanding of aminoglycoside-induced hearing loss and provide further evidence that stress granule formation is a fundamental cellular stress response.
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Affiliation(s)
- Emily R Towers
- UCL Ear Institute, 332 Gray's Inn Road, London WC1X 8EE, UK
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102
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Sturdy A, Goodman A, José RJ, Loyse A, O'Donoghue M, Kon OM, Dedicoat MJ, Harrison TS, John L, Lipman M, Cooke GS. Multidrug-resistant tuberculosis (MDR-TB) treatment in the UK: a study of injectable use and toxicity in practice. J Antimicrob Chemother 2011; 66:1815-20. [PMID: 21642291 DOI: 10.1093/jac/dkr221] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Multidrug-resistant tuberculosis (MDR-TB) is an increasing challenge to health services globally. Although new drugs are in development, current guidelines still recommend prolonged use of injectable antimicrobials (usually amikacin, kanamycin or capreomycin). The evidence base to inform treatment and monitoring strategies is very limited. METHODS We conducted a retrospective study of patients initiating injectable antimicrobials for MDR-TB treatment in five UK centres between January 2004 and December 2009. (i) Current treatment and monitoring strategies were reviewed. (ii) The incidence of ototoxicity (defined both clinically and on audiological testing) and factors associated with ototoxicity were investigated using logistic regression. RESULTS (i) The choice of injectable antimicrobial varied. Of 50 MDR-TB patients, 29/50 (58%) received amikacin, 11/50 (22%) received capreomycin and 10/50 (20%) received streptomycin or a combination; reflecting a difference in policy between centres. Only 21/50 (42%) patients received baseline screening by audiogram within 2 weeks of starting treatment and 16/50 (32%) then had monthly audiograms, with the majority screened more infrequently and 12/50 (24%) receiving no screening. (ii) Of the 50 patients, 14 (28%) experienced ototoxicity, with 9/50 (18%) left with long-term hearing loss. Increased age (P = 0.02), use of amikacin (P = 0.02) and decreased renal function (P = 0.01) were significantly associated with ototoxicity. CONCLUSIONS There is local variation in both the choice of injectable agent and in ototoxicity screening practices. Long-term morbidity from injectable treatment is significant even in this well-resourced setting, and the data suggest capreomycin might be associated with less ototoxicity when compared with amikacin. There is a need for more high-quality clinical data to inform future guidelines for treatment and monitoring.
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Affiliation(s)
- Ann Sturdy
- Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
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103
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Choung YH, Kim SW, Tian C, Min JY, Lee HK, Park SN, Lee JB, Park K. Korean red ginseng prevents gentamicin-induced hearing loss in rats. Laryngoscope 2011; 121:1294-302. [PMID: 21541943 DOI: 10.1002/lary.21756] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Accepted: 01/21/2011] [Indexed: 11/11/2022]
Abstract
OBJECTIVES To evaluate the preventive effects of Korean red ginseng (KRG) on gentamicin (GM)-induced ototoxicity and to identify the effective components of KRG. STUDY DESIGN In vivo and in vitro studies. METHODS Thirty-five Sprague-Dawley rats were divided into four groups. The GM group (n = 15) received intraperitoneal injections (IPI) of GM (160 mg/kg) for 5 days. The KRG + GM group (n = 12) was treated with intragastric feeding of KRG (500 mg/kg) for 12 days with 5 days of IPIs of GM. KRG (n = 4) and control (n = 4) groups were treated with KRG and saline, respectively. Auditory brainstem response (16 or 32 kHz) and Rotarod treadmill tests were done before and after treatments. Cochleas were evaluated by a scanning electron microscope (SEM) and phalloidin staining. Ginsenosides Rb1, Rb2, Rg1, and Re were evaluated as the water-soluble terazolium salt assay, annexin V/propidium iodide assay, and Western blots in HEI-OC1 cells. RESULTS Posttreatment hearing thresholds in GM, KRG + GM, KRG, and control groups were: 27.7 ± 7.2 dB, 23.1 ± 4.1 dB, 16.9 ± 2.6 dB, and 21.3 ± 3.5 dB, respectively, for 16 kHz, 30.5 ± 6.6 dB, 25.2 ± 4.3 dB, 22.5 ± 2.7 dB, and 22.5 ± 3.8 dB, respectively for 32 kHz. The KRG + GM group had significantly better hearing than the GM group (P < .05). On SEM and phalloidin staining, the GM group showed severe loss of stereocilia in the basal outer hair cells and a few losses in the middle turns, whereas the KRG + GM group showed relatively intact hair cells. Balance impairment in treadmill tests was not definite in any group. Rb1 and Rb2 showed more effective protection than other components. CONCLUSIONS KRG protects against GM-induced hearing loss and hair cell death in rats. Laryngoscope, 2011.
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Affiliation(s)
- Yun-Hoon Choung
- Department of Otolaryngology, Ajou University School of Medicine, Suwon, Republic of Korea
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104
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Palmay L, Walker SAN, Walker SE, Simor AE. Symptom Reporting Compared with Audiometry for the Detection of Cochleotoxicity in Patients on Long-Term Aminoglycoside Therapy. Ann Pharmacother 2011; 45:590-5. [DOI: 10.1345/aph.1p729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Background Aminoglycoside-associated auditory toxicity (cochleotoxicity) is a major concern in patients receiving prolonged aminoglycoside therapy. There are no published data comparing symptom monitoring to audiometry testing for the detection of aminoglycoside-induced cochleotoxicity; thus, agreement regarding the optimal monitoring of these patients for early detection of this effect is lacking. Objective: To compare the sensitivity of symptom monitoring to that of audiometry in identifying cochleotoxicity in patients on prolonged aminoglycoside therapy. Methods: A retrospective chart review of adult inpatients at Sunnybrook Health Sciences Centre prescribed prolonged aminoglycoside therapy (≥21 days) who completed at least 1 audiometry test between January 1, 1999, and December 31, 2009, was conducted. Data pertaining to results of audiometry testing and development of symptoms of auditory toxicity were collected. Symptom monitoring was compared with audiology testing for the detection of cochleotoxicity. Results: Forty eligible patients were included for analysis. Audiometry was significantly better than symptom monitoring to identify early cochleotoxicity (absolute risk reduction = 17.5% and number needed to treat = 6; p = 0.023). Compared to audiometry, symptom monitoring has a sensitivity, negative predictive value, and accuracy for the detection of early cochleotoxicity of 61%, 75%, and 82%, respectively. Conclusions: Audiometry testing is significantly better than monitoring symptoms to identify early aminoglycoside-induced auditory toxicity in patients prescribed prolonged aminoglycoside therapy (≥21 days). Subclinical cochleotoxicity identified with audiometry may allow early termination of aminoglycoside therapy to prevent progression of cochlear damage to the audible frequency range.
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Affiliation(s)
- Lesley Palmay
- Department of Pharmacy, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Sandra AN Walker
- Pharmacy, Leslie Dan Faculty of Pharmacy, University of Toronto; Clinical Coordinator, Infectious Diseases, Department of Pharmacy, Sunnybrook Health Sciences Centre
| | - Scott E Walker
- Pharmacy, Leslie Dan Faculty of Pharmacy; Director of Pharmacy, Sunnybrook Health Sciences Centre
| | - Andrew E Simor
- Department of Microbiology and Infectious Diseases, Sunnybrook Health Sciences Centre
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Involvement of calpain-I and microRNA34 in kanamycin-induced apoptosis of inner ear cells. Cell Biol Int 2011; 34:1219-25. [PMID: 21067520 DOI: 10.1042/cbi20100515] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Inner ear cells, including hair cells, spiral ganglion cells, stria vascularis cells and supporting cells on the basilar membrane, play a major role in transducing hearing signals and regulating inner ear homoeostasis. However, their functions are often damaged by antibiotic-induced ototoxicity. Apoptosis is probably involved in inner ear cell injury following aminoglycoside treatment. Calpain, a calcium-dependent protease, is essential for mediating and promoting cell death. We have therefore investigated the involvement of calpain in the molecular mechanism underlying ototoxicity induced by the antibiotic kanamycin in mice. Kanamycin (750 mg/kg) mainly induced cell death of cochlear cells, including stria vascularis cells, supporting cells and spiral ganglion cells, but not hair cells within the organ of Corti. Cell death due to apoptosis occurred in a time-dependent manner with concomitant up-regulation of calpain expression. Furthermore, the expression levels of two microRNAs, mir34a and mir34c, were altered in a dose-dependent manner in cochlear cells. These novel findings demonstrated the involvement of both calpain and microRNAs in antibiotic-induced ototoxicity.
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106
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Abstract
PURPOSE OF REVIEW To summarize advances in the study of the interaction between sensory hair cells and aminoglycoside antibiotics. RECENT FINDINGS Aminoglycosides enter hair cells through mechanotransduction channels and initiate an active signaling pathway that leads to cell death. Early expression of heat shock proteins can protect hair cells from aminoglycosides, although signaling from surrounding supporting cells appears to promote hair cell death. Studies of certain human deafness mutations have revealed new insights into the role of mitochondria in aminoglycoside ototoxicity. SUMMARY The cellular mechanisms of aminoglycoside ototoxicity continue to be an active topic of research and newly developed animal models offer great promise for future advances. Nevertheless, proven clinical methods for the prevention of ototoxic injury are not yet available.
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107
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Hirose K, Sato E. Comparative analysis of combination kanamycin-furosemide versus kanamycin alone in the mouse cochlea. Hear Res 2010; 272:108-16. [PMID: 21044672 DOI: 10.1016/j.heares.2010.10.011] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 10/21/2010] [Accepted: 10/21/2010] [Indexed: 10/18/2022]
Abstract
Combinations of aminoglycosides and loop diuretics have been known to have a synergistic effect in ototoxic injury. Because murine hair cells are relatively resistant to ototoxicity compared to those of other mammals, investigators have turned to combination therapies to create ototoxic lesions in the mouse inner ear. In this paper, we perform a systematic comparison of hearing thresholds, hair cell damage and monocyte migration into the mouse cochlea after kanamycin versus combined kanamycin/furosemide and explore the pathophysiology of enhanced hair cell loss in aminoglycoside ototoxicity in the presence of loop diuretic. Combined kanamycin-furosemide resulted in elevation of threshold not only in the high frequencies, but across all frequencies with more extensive loss of outer hair cells when compared to kanamycin alone. The stria vascularis was severely atrophied and stellate cells in the spiral limbus were missing in kanamycin-furosemide exposed mice while these changes were not observed in mice receiving kanamycin alone. Monocytes and macrophages were recruited in large numbers to the spiral ligament and spiral ganglion in these mice. Combination therapy resulted in a greater number of macrophages in total, and many more macrophages were present further apically when compared to mice given kanamycin alone. Combined kanamycin-furosemide provides an effective method of addressing the relative resistance to ototoxicity that is observed in most mouse strains. As the mouse becomes increasingly more common in studies of hearing loss, and combination therapies gain popularity, recognition of the overall effects of combined aminoglycoside-loop diuretic therapy will be critical to interpretation of the interventions that follow.
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Affiliation(s)
- Keiko Hirose
- Department of Otolaryngology, Washington University, 660 South Euclid Avenue, Campus Box 8115, St. Louis, MO 63110, United States.
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108
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Dille MF, Konrad-Martin D, Gallun F, Helt WJ, Gordon JS, Reavis KM, Bratt GW, Fausti SA. Tinnitus onset rates from chemotherapeutic agents and ototoxic antibiotics: results of a large prospective study. J Am Acad Audiol 2010; 21:409-17. [PMID: 20701838 DOI: 10.3766/jaaa.21.6.6] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND AND PURPOSE To report on the incidence and relative risk of tinnitus onset from a variety of drug therapies known to be ototoxic. Two main questions were asked: (1) What is the prevalence and incidence of tinnitus among patients treated with cisplatin, carboplatin, or ototoxic antibiotic therapies? (2) Do commonly reported treatment or subject factors confound or modify the incidence of tinnitus onset? DATA COLLECTION AND ANALYSIS A prospective observational study design was used to evaluate occurrence of significant otologic changes in 488 veterans (962 ears) receiving chemotherapeutic agents (cisplatin, carboplatin), ototoxic antibiotics (primarily aminoglycoside), or nonototoxic drugs (control medications). A subset of 260 veterans lacking tinnitus prior to drug exposure was used to compare rates of tinnitus onset. Subjects were tested prior to, during, and following their treatment. Planned comparisons using logistic regression, analysis of variance (ANOVA), and chi(2) statistics were made among groups by the type of medication taken, age, presence of preexisting hearing loss, days on drug, and cumulative dose of drug. RESULTS Baseline tinnitus rates were high (nearly 47%) relative to the general population of a similar age. Subjects with exposure to ototoxic medications had significantly increased risk for developing tinnitus. Those on chemotherapeutic agents were found to have the greatest risk. Cisplatin elevated the risk by 5.53 times while carboplatin increased the risk by 3.75 over nonototoxic control medications. Ototoxic antibiotics resulted in borderline risk (2.81) for new tinnitus. Contrary to other reports, we did not find that subject factors (increased age or pre-existing hearing loss) or treatment factors (days on drug or cumulative dose) contributed to rates of tinnitus onset during treatment. CONCLUSIONS This large prospective study confirms that new tinnitus during treatment is associated with chemotherapy and with certain ototoxic antibiotic treatment. Cisplatin and carboplatin were found to be the most potent ototoxic agents causing tinnitus at much greater numbers than the other drugs studied. Implications for counseling and audiological resource allocation are discussed.
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Affiliation(s)
- Marilyn F Dille
- VA RR & D National Center for Rehabilitative Auditory Research, Portland VA Medical Center, Portland, OR 97239, USA.
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109
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Abstract
Hearing loss is one of the most common sensory impairments and affects almost 10% of the adult population. The percentage of adults with hearing loss markedly increases with advancing age. The differential diagnosis for patients presenting with hearing loss is extensive, but can often be narrowed with a directed hearing history and physical examination. The severity of the hearing loss may warrant additional diagnostic studies, including audiometry, and possible imaging in selected cases. Hearing aids, assistive listening devices, middle ear surgery, and cochlear implantation are potential therapeutic options available to patients depending on the type and severity of the hearing loss.
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Affiliation(s)
- Brandon Isaacson
- Department of Otolaryngology - Head and Neck Surgery, UT - Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9035, USA.
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110
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Arnold A, Brouse SD, Pitcher WD, Hall RG. Empiric therapy for gram-negative pathogens in nosocomial and health care-associated pneumonia: starting with the end in mind. J Intensive Care Med 2010; 25:259-70. [PMID: 20622257 DOI: 10.1177/0885066610371189] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Nosocomial pneumonia is a major cause of morbidity and mortality for hospitalized patients. Antimicrobial resistance is increasing, creating a strain between ensuring the provision of adequate empiric therapy and slowing the development of antimicrobial resistance. Excessive antimicrobial therapy places patients are at greater risk of drug interactions, adverse events, and superinfections. Ways to maximize adequate empiric therapy include (1) categorizing each patient's risk of being infected with a multidrug-resistant pathogen and knowledge of local susceptibility patterns, (2) de-escalating antimicrobial therapy to decrease the rates of superinfections such as Clostridium difficile, and (3) limiting the duration of therapy to decrease the likelihood of adverse events, drug interactions, and antimicrobial resistance. Pharmacodynamically enhanced dosing regimens also have the potential to improve clinical outcomes and slow the development of antimicrobial resistance. Drugs whose killing is optimized by the percentage time above the minimum inhibitory concentration (MIC), such as beta-lactams, can be given by continuous or extended infusion to provide superior pharmacodynamic (PD) target attainment rates compared with traditional regimens. Drugs whose killing is optimized with a high-peak plasma concentration to MIC ratio (eg, aminoglycosides) should be administered once daily to maximize the likelihood of achieve optimal target attainment rates. Drugs whose killing is optimized by the ratio of the area under the curve (AUC) to MIC ratio (eg, fluoroquinolones) depend on the total daily dose as opposed to the dosing schedule or infusion time. Determining the optimal drug dosing schedules for obese patients remains critical because these patients have may have significantly increased volumes of distribution and clearance rates compared to normal weight patients. Optimizing the use of current antimicrobials is paramount to ensure quality treatment options are available, given the lack of gram-negative antimicrobials in the pipeline.
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Affiliation(s)
- Amy Arnold
- Texas Tech University Health Sciences Center, Dallas, TX 75235, USA
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111
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Coffin AB, Ou H, Owens KN, Santos F, Simon JA, Rubel EW, Raible DW. Chemical screening for hair cell loss and protection in the zebrafish lateral line. Zebrafish 2010; 7:3-11. [PMID: 20192852 DOI: 10.1089/zeb.2009.0639] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In humans, most hearing loss results from death of hair cells, the mechanosensory receptors of the inner ear. Two goals of current hearing research are to protect hair cells from degeneration and to regenerate new hair cells, replacing those that are lost due to aging, disease, or environmental challenges. One limitation of research in the auditory field has been the relative inaccessibility of the mechanosensory systems in the inner ear. Zebrafish possess hair cells in both their inner ear and their lateral line system that are morphologically and functionally similar to human hair cells. The external location of the mechanosensory hair cells in the lateral line and the ease of in vivo labeling and imaging make the zebrafish lateral line a unique system for the study of hair cell toxicity, protection, and regeneration. This review focuses on the lateral line system as a model for understanding loss and protection of mechanosensory hair cells. We discuss chemical screens to identify compounds that induce hair cell loss and others that protect hair cells from known toxins and the potential application of these screens to human medicine.
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Affiliation(s)
- Allison B Coffin
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195-7923, USA.
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112
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McDade EJ, Wagner JL, Moffett BS, Palazzi DL. Once-daily gentamicin dosing in pediatric patients without cystic fibrosis. Pharmacotherapy 2010; 30:248-53. [PMID: 20180608 DOI: 10.1592/phco.30.3.248] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
STUDY OBJECTIVE To estimate an appropriate once-daily gentamicin dose and dosing interval for non-critical care pediatric patients older than 3 months of age without cystic fibrosis. DESIGN Pharmacokinetic analysis of data from a retrospective medical record review. SETTING Large academic children's hospital. PATIENTS One hundred fourteen non-critical care pediatric patients older than 3 months of age without cystic fibrosis who received multiple-daily dosing regimens of gentamicin between September 2007 and April 2008. MEASUREMENTS AND MAIN RESULTS Patient-specific pharmacokinetic parameters were calculated using drug concentrations obtained at steady state. Once-daily doses were extrapolated for each patient to achieve goal peak and trough concentrations. Using the average of these doses and the patient-specific pharmacokinetic parameters, theoretical once-daily peak and trough concentrations were calculated for each patient. Patient characteristics were analyzed to determine differences between patients who did and those who did not achieve adequate peak concentrations. Mean +/- SD pharmacokinetic parameters were as follows: elimination rate constant 0.32 +/- 0.06 hour(-1), half-life 2.28 +/- 0.54 hours, and volume of distribution 0.24 +/- 0.08 L/kg. The only patient demographic characteristic found to have a significant effect on the extrapolated peak concentration was age. The following age-specific once-daily doses were calculated: 3 months to less than 2 years, 9.5 mg/kg; 2 years to less than 8 years, 8.5 mg/kg; and 8-18 years, 7 mg/kg. CONCLUSION Age was the primary factor in determining the once-daily dose of gentamicin in our pediatric population. Further prospective research is necessary to determine the safety and efficacy of these age-based, once-daily doses for gentamicin.
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Affiliation(s)
- Erin J McDade
- Department of Pharmacy, Texas Children's Hospital, Houston, Texas 77030, USA
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113
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Abstract
Cisplatin is a chemotherapeutic agent that is widely used in the treatment of solid tumors. Ototoxicity is a common side effect of cisplatin therapy and often leads to permanent hearing loss. The sensory organs of the avian ear are able to regenerate hair cells after aminoglycoside ototoxicity. This regenerative response is mediated by supporting cells, which serve as precursors to replacement hair cells. Given the antimitotic properties of cisplatin, we examined whether the avian ear was also capable of regeneration after cisplatin ototoxicity. Using cell and organ cultures of the chick cochlea and utricle, we found that cisplatin treatment caused apoptosis of both auditory and vestibular hair cells. Hair cell death in the cochlea occurred in a unique pattern, progressing from the low-frequency (distal) region toward the high-frequency (proximal) region. We also found that cisplatin caused a dose-dependent reduction in the proliferation of cultured supporting cells as well as increased apoptosis in those cells. As a result, we observed no recovery of hair cells after ototoxic injury caused by cisplatin. Finally, we explored the potential for nonmitotic hair cell recovery via activation of Notch pathway signaling. Treatment with the gamma-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester failed to promote the direct transdifferentiation of supporting cells into hair cells in cisplatin-treated utricles. Taken together, our data show that cisplatin treatment causes maintained changes to inner ear supporting cells and severely impairs the ability of the avian ear to regenerate either via proliferation or by direct transdifferentiation.
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114
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Poirrier A, Van den Ackerveken P, Kim T, Vandenbosch R, Nguyen L, Lefebvre P, Malgrange B. Ototoxic drugs: Difference in sensitivity between mice and guinea pigs. Toxicol Lett 2010; 193:41-9. [DOI: 10.1016/j.toxlet.2009.12.003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Revised: 12/02/2009] [Accepted: 12/06/2009] [Indexed: 01/18/2023]
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115
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Protection against noise-induced hearing loss in young CBA/J mice by low-dose kanamycin. J Assoc Res Otolaryngol 2010; 11:235-44. [PMID: 20094753 DOI: 10.1007/s10162-009-0204-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Accepted: 12/09/2009] [Indexed: 10/19/2022] Open
Abstract
Animal studies indicate that a combination of kanamycin (KM) and noise produces a synergistic effect, whereby the threshold shift from the combination is greater than the sum of the shifts caused by either agent alone. Most such studies have focused on adult animals, and it has remained unclear whether younger, presumably more susceptible, animals show an even greater synergistic effect. The present study tested the hypothesis that young CBA/J mice receiving a low dose of KM (300 mg/kg, 2x/day, s.c.) from 20 to 30 days post-gestational age followed by brief noise exposure (110 dB SPL; 4-45 kHz, 30 s) would show greater noise-induced permanent threshold shifts (NIPTS) than mice receiving either treatment alone. Noise exposure produced 30-40 dB of NIPTS and moderate hair cell loss in young saline-treated mice. KM alone at this dose had no effect on thresholds. Surprisingly, mice receiving KM plus noise were protected from NIPTS, showing ABR thresholds not significantly different from unexposed controls. Mice receiving KM prior to noise exposure also showed significantly less outer hair cell loss than saline-treated mice. Additional experiments indicated protection by KM when the noise was applied either 24 or 48 h after the last KM injection. Our results demonstrate a powerful protective effect of sub-chronic low-dose kanamycin against NIPTS in young CBA/J mice. Repeated kanamycin exposure may establish a preconditioned protective state, the molecular bases of which remain to be determined.
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116
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Brenner GM, Stevens CW. Inhibitors of Bacterial Protein Synthesis. Pharmacology 2010. [DOI: 10.1016/b978-1-4160-6627-9.00039-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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117
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de Klaver PAG, de Koning J, Janssen RPA, Derijks LJJ. High systemic gentamicin levels and ototoxicity after implantation of gentamicin beads in a 70-year-old man--a case report. Acta Orthop 2009; 80:734-6. [PMID: 19995323 PMCID: PMC2823315 DOI: 10.3109/17453670903487032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Affiliation(s)
| | | | - Rob P A Janssen
- Departments of Orthopedic Surgery and Traumatology, Máxima Medical Center, Veldhoven, the Netherlands
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118
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Owens KN, Coffin AB, Hong LS, Bennett KO, Rubel EW, Raible DW. Response of mechanosensory hair cells of the zebrafish lateral line to aminoglycosides reveals distinct cell death pathways. Hear Res 2009; 253:32-41. [PMID: 19285126 DOI: 10.1016/j.heares.2009.03.001] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 02/15/2009] [Accepted: 03/04/2009] [Indexed: 01/01/2023]
Abstract
We report a series of experiments investigating the kinetics of hair cell loss in lateral line neuromasts of zebrafish larvae following exposure to aminoglycoside antibiotics. Comparisons of the rate of hair cell loss and the differential effects of acute versus chronic exposure to gentamicin and neomycin revealed markedly different results. Neomycin induced rapid and dramatic concentration-dependent hair cell loss that is essentially complete within 90 min, regardless of concentration or exposure time. Gentamicin-induced loss of half of the hair cells within 90 min and substantial additional loss, which was prolonged and cumulative over exposure times up to at least 24h. Small molecules and genetic mutations that inhibit neomycin-induced hair cell loss were ineffective against prolonged gentamicin exposure supporting the hypothesis that these two drugs are revealing at least two cellular pathways. The mechanosensory channel blocker amiloride blocked both neomycin and gentamicin-induced hair cell death acutely and chronically indicating that these aminoglycosides share a common entry route. Further tests with additional aminoglycosides revealed a spectrum of differential responses to acute and chronic exposure. The distinctions between the times of action of these aminoglycosides indicate that these drugs induce multiple cell death pathways.
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Affiliation(s)
- Kelly N Owens
- Department of Biological Structure, V.M. Bloedel Hearing Research Center, University of Washington, Box 357420, Seattle, WA 98195-7420, USA.
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119
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Frequency of mitochondrial 12S ribosomal RNA variants in an adult cystic fibrosis population. Pharmacogenet Genomics 2009; 18:1095-102. [PMID: 18830133 DOI: 10.1097/fpc.0b013e328312b072] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In adult cystic fibrosis patient populations, gram-negative bacteria, particularly Pseudomonas aeruginosa, frequently require aggressive therapy including systemic antibiotics, bronchodilators and airway clearance techniques. Aminoglycosides including tobramycin are used frequently to control these chronic airway infections. They, however, cause important nephrotoxic and ototoxic effects that can significantly alter the quality of life. We investigated the genetic predisposition to aminoglycoside ototoxicity in a typical unscreened North American cystic fibrosis population by screening for variants in mitochondrial 12S ribosomal RNA and noted several polymorphisms occurred at higher frequencies than expected and were associated with clinically significant cases of hearing loss. In the population studied, both patients possessing the 1555A>G transition exhibited profound ototoxicity after nontoxic dosing of tobramycin. We also identified new homoplasmic genetic variations in the mitochondrial 12S ribosomal RNA, several of which occurred in highly conserved regions of the gene and were present in patients with moderate-to-severe ototoxicity after exposure to aminoglycosides.
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Ou HC, Cunningham LL, Francis SP, Brandon CS, Simon JA, Raible DW, Rubel EW. Identification of FDA-approved drugs and bioactives that protect hair cells in the zebrafish (Danio rerio) lateral line and mouse (Mus musculus) utricle. J Assoc Res Otolaryngol 2009; 10:191-203. [PMID: 19241104 DOI: 10.1007/s10162-009-0158-y] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Accepted: 01/20/2009] [Indexed: 11/24/2022] Open
Abstract
The hair cells of the larval zebrafish lateral line provide a useful preparation in which to study hair cell death and to screen for genes and small molecules that modulate hair cell toxicity. We recently reported preliminary results from screening a small-molecule library for compounds that inhibit aminoglycoside-induced hair cell death. To potentially reduce the time required for development of drugs and drug combinations that can be clinically useful, we screened a library of 1,040 FDA-approved drugs and bioactive compounds (NINDS Custom Collection II). Seven compounds that protect against neomycin-induced hair cell death were identified. Four of the seven drugs inhibited aminoglycoside uptake, based on Texas-Red-conjugated gentamicin uptake. The activities of two of the remaining three drugs were evaluated using an in vitro adult mouse utricle preparation. One drug, 9-amino-1,2,3,4-tetrahydroacridine (tacrine) demonstrated conserved protective effects in the mouse utricle. These results demonstrate that the zebrafish lateral line can be used to screen successfully for drugs within a library of FDA-approved drugs and bioactives that inhibit hair cell death in the mammalian inner ear and identify tacrine as a promising protective drug for future studies.
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Affiliation(s)
- Henry C Ou
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Box 357923, Seattle, WA 98195, USA.
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Acute copper exposure induces oxidative stress and cell death in lateral line hair cells of zebrafish larvae. Brain Res 2008; 1244:1-12. [DOI: 10.1016/j.brainres.2008.09.050] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2008] [Revised: 08/27/2008] [Accepted: 09/11/2008] [Indexed: 01/11/2023]
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Cristobal R, Oghalai JS. Hearing loss in children with very low birth weight: current review of epidemiology and pathophysiology. Arch Dis Child Fetal Neonatal Ed 2008; 93:F462-8. [PMID: 18941031 PMCID: PMC3597102 DOI: 10.1136/adc.2007.124214] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
An association between birth weight <1500 g (very low birth weight (VLBW)) and hearing loss has been long recognised. As universal hearing screening programmes have become widely implemented and the survival rate of VLBW babies in modern intensive care units has increased, we have gained a substantially better understanding of the nature of this problem. However, many gaps in our knowledge base exist. This review describes recent data on hearing loss in the VLBW population and explains the current level of understanding about the physiological basis underlying the auditory deficits in these patients. Although VLBW alone may not have a severe impact on hearing, it is commonly associated with multiple other risk factors that can alter hearing in a synergistic fashion. Therefore, the risk of hearing loss is substantially higher than in the general newborn population. Also, it is important to perform a more comprehensive audiometric evaluation than standard otoacoustic emission screening for infants who are in the neonatal intensive care unit in order not to miss hearing loss due to retrocochlear pathology. Furthermore, children with VLBW are also at increased risk of experiencing progressive or delayed-onset hearing loss, and thus should continue to have serial hearing evaluations after discharge from the neonatal intensive care unit.
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Affiliation(s)
- R Cristobal
- Bobby R Alford Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, USA
| | - J S Oghalai
- Bobby R Alford Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, USA,The Hearing Center at Texas Children’s Hospital, Houston, Texas, USA,Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA,Department of Bioengineering, Rice University, Houston, Texas, USA
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