Hippo/YAP signaling pathway protects against neomycin-induced hair cell damage in the mouse cochlea.

The Hippo/Yes-associated protein (YAP) signaling pathway has been shown to be able to maintain organ size and homeostasis by regulating cell proliferation, differentiation, and apoptosis. The abuse of aminoglycosides is one of the main causes of sensorineural hearing loss (SSNHL). However, the role of the Hippo/YAP signaling pathway in cochlear hair cell (HC) damage protection in the auditory field is still unclear. In this study, we used the YAP agonist XMU-MP-1 (XMU) and the inhibitor Verteporfin (VP) to regulate the Hippo/YAP signaling pathway in vitro. We showed that YAP overexpression reduced neomycin-induced HC loss, while downregulated YAP expression increased HC vulnerability after neomycin exposure in vitro. We next found that activation of YAP expression inhibited C-Abl-mediated cell apoptosis, which led to reduced HC loss. Many previous studies have reported that the level of reactive oxygen species (ROS) is significantly increased in cochlear HCs after neomycin exposure. In our study, we also found that YAP overexpression significantly decreased ROS accumulation, while downregulation of YAP expression increased ROS accumulation. In summary, our results demonstrate that the Hippo/YAP signaling pathway plays an important role in reducing HC injury and maintaining auditory function after aminoglycoside exposure. YAP overexpression could protect against neomycin-induced HC loss by inhibiting C-Abl-mediated cell apoptosis and decreasing ROS accumulation, suggesting that YAP could be a novel therapeutic target for aminoglycosides-induced sensorineural hearing loss in the clinic.

A genome-wide analysis of targets of macrolide antibiotics in mammalian cells.

Macrolide antibiotics, such as erythromycin and josamycin, are natural polyketide products harboring 14- to 16-membered macrocyclic lactone rings to which various sugars are attached. These antibiotics are used extensively in the clinic because of their ability to inhibit bacterial protein synthesis. More recently, some macrolides have been shown to also possess anti-inflammatory and other therapeutic activities in mammalian cells. To better understand the targets and effects of this drug class in mammalian cells, we used a genome-wide shRNA screen in K562 cancer cells to identify genes that modulate cellular sensitivity to josamycin. Among the most sensitizing hits were proteins involved in mitochondrial translation and the mitochondrial unfolded protein response, glycolysis, and the mitogen-activated protein kinase signaling cascade. Further analysis revealed that cells treated with josamycin or other antibacterial agents exhibited impaired oxidative phosphorylation and metabolic shifts to glycolysis. Interestingly, we observed that knockdown of the mitogen-activated protein kinase kinase kinase 4 (MAP3K4) gene, which contributes to p38 mitogen-activated protein kinase signaling, sensitized cells only to josamycin but not to other antibacterial agents. There is a growing interest in better characterizing the therapeutic effects and toxicities of antibiotics in mammalian cells to guide new applications in both cellular and clinical studies. To our knowledge, this is the first report of an unbiased genome-wide screen to investigate the effects of a clinically used antibiotic on human cells.

Lower ototoxicity and absence of hidden hearing loss point to gentamicin C1a and apramycin as promising antibiotics for clinical use.

Spread of antimicrobial resistance and shortage of novel antibiotics have led to an urgent need for new antibacterials. Although aminoglycoside antibiotics (AGs) are very potent anti-infectives, their use is largely restricted due to serious side-effects, mainly nephrotoxicity and ototoxicity. We evaluated the ototoxicity of various AGs selected from a larger set of AGs on the basis of their strong antibacterial activities against multidrug-resistant clinical isolates of the ESKAPE panel: gentamicin, gentamicin C1a, apramycin, paromomycin and neomycin. Following local round window application, dose-dependent effects of AGs on outer hair cell survival and compound action potentials showed gentamicin C1a and apramycin as the least toxic. Strikingly, although no changes were observed in compound action potential thresholds and outer hair cell survival following treatment with low concentrations of neomycin, gentamicin and paromomycin, the number of inner hair cell synaptic ribbons and the compound action potential amplitudes were reduced. This indication of hidden hearing loss was not observed with gentamicin C1a or apramycin at such concentrations. These findings identify the inner hair cells as the most vulnerable element to AG treatment, indicating that gentamicin C1a and apramycin are promising bases for the development of clinically useful antibiotics.

In vitro evaluation of biomarkers of nephrotoxicity through gene expression using gentamicin.

Acute renal failure is one of the most frequent effects observed after taking medicine. Such situations have been tardily discovered, given that existing methods for assessing toxicity are not predictive. In this light, the present work evaluated the effects of gentamicin, a form of nephrotoxic drug, on HK-2 and HEK-293 cells. By using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and flow cytometry, both cells demonstrated that cytotoxicity occurs in a dose-dependent manner through the processes of apoptosis and cell necrosis. Gene expression analysis showed a relative increase of expression for genes related to cell processes and classic biomarkers, such as TP53, CASP3, CASP8, CASP9, ICAM-1, EXOC3, KIM-1, and CST3. A decrease in expression for genes BCL2L1 and EGF was observed. This study, therefore, indicates that, when the methods are used together, gene expression analysis is able to evaluate the nephrotoxic potential of a substance.

Linezolid: a review of its properties, function, and use in critical care.

Linezolid can be considered as the first member of the class of oxazolidinone antibiotics. The compound is a synthetic antibiotic that inhibits bacterial protein synthesis through binding to rRNA. It also inhibits the creation of the initiation complex during protein synthesis which can reduce the length of the developed peptide chains, and decrease the rate of reaction of translation elongation. Linezolid has been approved for the treatment of infections caused by vancomycin-resistant Enterococcus faecium, hospital-acquired pneumonia caused by Staphylococcus aureus, complicated skin and skin structure infections (SSSIs), uncomplicated SSSIs caused by methicillin-susceptible S. aureus or Streptococcus pyogenes, and community-acquired pneumonia caused by Streptococcus pneumoniae. Analysis of high-resolution structures of linezolid has demonstrated that it binds a deep cleft of the 50S ribosomal subunit that is surrounded by 23S rRNA nucleotides. Mutation of 23S rRNA was shown to be a linezolid resistance mechanism. Besides, mutations in specific regions of ribosomal proteins uL3 and uL4 are increasingly associated with linezolid resistance. However, these proteins are located further away from the bound drug. The methicillin-resistant S. aureus and vancomycin-resistant enterococci are considered the most common Gram-positive bacteria found in intensive care units (ICUs), and linezolid, as an antimicrobial drug, is commonly utilized to treat infected ICU patients. The drug has favorable in vitro and in vivo activity against the mentioned organisms and is considered as a useful antibiotic to treat infections in the ICU.

Tauroursodeoxycholic acid attenuates gentamicin-induced cochlear hair cell death in vitro.

Gentamycin is one of the most clinically used aminoglycoside antibiotics which induce intrinsic apoptosis of hair cells. Tauroursodeoxycholic acid (TUDCA) is known as safe cell-protective agent in disorders associated with apoptosis. We aimed to investigate the protective effects of TUDCA against gentamicin-induced ototoxicity. House Ear Institute-Organ of Corti 1(HEI-OC1) cells and explanted cochlear tissue were treated with gentamicin and TUDCA, followed by serial analyses including cell viability assay, hair cell staining, qPCR, ELISA and western blotting to determine the cell damage by the parameters relevant to cell apoptosis and endoplasmic reticulum stress. TUDCA significantly attenuated gentamicin-induced cell damage in cultured HEI-OC1 cells and explanted cochlear hair cells. TUDCA alleviated gentamicin-induced cell apoptosis, supported by the decreased Bax/Bcl2 ratio compared with that of gentamicin treated alone. TUDCA decreased gentamicin-induced nitric oxide production and protein nitration in both models. In addition, TUDCA suppressed gentamicin-induced endoplasmic reticulum stress as reflected by inversing the expression levels of Binding immunoglobulin protein (Bip), CCAAT/-enhancer-binding protein homologous protein (CHOP) and Caspase 3. TUDCA attenuated gentamicin-induced hair cell death by inhibiting protein nitration activation and ER stress, providing new insights into the new potential therapies for sensorineural deafness.

Telbivudine attenuates gentamicin-induced kidney injury in rats.

Nephrotoxicity has been associated with nucleos(t)ide analogues other than telbivudine (LdT). This study investigated the potential effects of LdT and lamivudine (LAM) on renal function in an experimental rat model of gentamicin-induced acute nephrotoxicity. A total of 28 healthy Wistar albino rats were randomly divided into four experimental groups: negative control; positive control (PC); LdT; and LAM. Nephrotoxicity was induced by gentamicin in the LdT, LAM and PC groups. LdT and LAM were administered to two groups for 6 weeks starting on the ninth day. Blood samples were collected weekly and cystatin C levels were measured by ELISA. Animals were sacrificed on the 50th day and the kidneys were removed for histological examination. Serum cystatin C levels differed significantly between the LdT and LAM groups (P <0.007) and between the LdT and PC groups (P <0.001). Renal function was significantly improved in the LdT group at the start of antiviral treatment on Day 8 and at the end of treatment on Day 50 (P = 0.001 and 0.007). Glomerular injury, acute tubular necrosis and total injury score were significantly reduced in the LdT group relative to the PC and LAM groups upon histopathological examination. LdT was associated with significant improvements in renal function as measured by biochemical and histopathological methods. The acute kidney injury model data should be supported by clinical studies to suggest that LdT treatment may have advantages for patients with underlying chronic kidney disease receiving chronic hepatitis B treatment.

Melatonin mitigates neomycin-induced hair cell injury in zebrafish.

CONTEXT: Ototoxicity due to medications, such as aminoglycosides, is irreversible, and free radicals in the inner ear are assumed to play a major role. Because melatonin has an antioxidant property, we hypothesize that it might mitigate hair cell injury by aminoglycosides. OBJECTIVE: The objective of this study was to evaluate whether melatonin has an alleviative effect on neomycin-induced hair cell injury in zebrafish (Danio rerio). METHODS: Various concentrations of melatonin were administered to 5-day post-fertilization zebrafish treated with 125 µM neomycin for 1 h. Surviving hair cells within four neuromasts were compared with that of a control group. Apoptosis was assessed via terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. The changes of ultrastructure were confirmed using a scanning electron microscope. RESULTS: Melatonin alleviated neomycin-induced hair cell injury in neuromasts (neomycin + melatonin 100 µM: 13.88 ± 0.91 cells, neomycin only: 7.85 ± 0.90 cells; n = 10, p < 0.05) and reduced neomycin-induced apoptosis in the TUNEL assay. In ultrastructural analysis, hair cells within the neuromasts in zebrafish were preserved exposed to 125 µM neomycin and 100 µM melatonin for 1 h in SEM findings. CONCLUSION: Melatonin is effective in alleviating aminoglycoside-induced hair cell injury in zebrafish. The results of this study demonstrated that melatonin has the potential to reduce apoptosis induced by aminoglycosides in zebrafish.

Assessment of Vestibulo-oculomotor Reflex in Ménière's Disease: Defining an Instrumental Profile.

OBJECTIVES: To analyze and compare, in two groups of patients affected by definite Ménière's disease (MD) but treated differently, the Video Head Impulse Test findings especially by putting them in relationship with canal paresis, hearing loss, and duration of the disease. STUDY DESIGN: Retrospective chart review. PATIENTS: Seventy patients affected by unilateral definite MD (16 in Group 1 and 54 in Group 2) observed between March 2014 and May 2015 in a tertiary referral center were retrospectively studied and then divided into two groups: Group 1 was previously treated with intratympanic gentamicin, whereas Group 2 underwent only a conservative therapy. Instrumental tests included audiometry, caloric test, and Video Head Impulse Test. All the findings were statistically analyzed; significance was set at p = 0.005. INTERVENTION: Diagnostic. MAIN OUTCOMES MEASURES: If MD is treated conservatively the high-frequency vestibulo-oculomotor reflex gain determined with Video Head Impulse Test is normal; it is pathological if MD is treated with gentamicin. RESULTS: High-frequency vestibulo-oculomotor reflex gain showed a statistically significant reduction in Group 1; at the same time, it showed no correlation in both groups with hearing loss, duration of disease or canal paresis. CONCLUSION: High-frequency vestibulo-oculomotor reflex is naturally preserved even in late stage MD if the patient has been treated conservatively; the dissociation between Caloric Test and Video Head Impulse Test findings could be considered an instrumental hallmark of MD. Gentamicin significantly reduces high-frequency vestibulo-oculomotor reflex gain: this reduction can be taken into account when determining the effectiveness of an ablative treatment.

The effect of poly (ADP-ribose) polymerase inhibition on aminoglycoside-induced acute tubular necrosis in rats.

INTRODUCTION: Aminoglycosides (AG) cause nephrotoxicity in 10 - 20% of patients. One of the mechanisms is by generating reactive oxygen species (ROS), leading to DNA destruction and activation of poly(ADPribose) polymerase (PARP) causing necrotic tubular cell death. PARP inhibition on gentamicin-induced nephrotoxicity was studied. METHODS: 19 female Wistar-Kyoto rats divided into 3 groups: control (3 rats receiving no treatment); gentamicin-treated group (8 rats); and 8 rats treated with gentamicin combined with 3-aminobenzamide (3 AB). Kidney functions, protein, and gentamicin levels as well as urinary trypsin inhibitory activity (TIA) were measured. Tissue microscopic examination and immunohistochemical study for proliferative cell nuclear antigen (PCNA) were determined. The effect of PARP inhibitor on the bactericidal activity of gentamicin was also assessed. RESULTS: The following results were statistically significant: urea (mg/dL) 39.9 ± 5.86, 88.3 ± 50.3, and 48.5 ± 12.7 (p = 0.048); serum creatinine (mg/dL): 0.6 ± 0.26, 1.05 ± 0.7, 0.6 ± 0.06 (p = 0.043); proteinuria (mg/24-hours): 7.27 ± 3.65, 41.2 ± 18.1, and 17.6 ± 13.9 (p = 0.050); the number of tubular macronuclei (per 10 mm2): 18.33 ± 16.07, 218 ± 101.8, 41.7 ± 36.2 (p = 0.012); the number of dilated tubes (per 10 mm2): 61.67 ± 12.58, 276.3 ± 112.7, 140.0 ± 90.9 (p = 0.04); and the number of PCNA positive nuclei (per 10 mm2): 223.3 ± 95.69, 3,585 ± 2,215.3, 626.7 ± 236.9 (p = 0.034) in the control, gentamicin, and gentamicin+3AB-treated groups, respectively. The following biochemical and histologic parameters were also examined, however, they showed no statistically significant difference: TIA (p = 0.055), mitoses (p = 0.14), mononuclear infiltrate (p = 0.188), and intratubular cast formation (p = 0.084). No effect on bactericidal activity was observed. CONCLUSION: This study illustrates that PARP inhibitor significantly attenuates gentamicin-induced nephrotoxicity in rats with no effect on the bactericidal activity.

Phenotypic Screening Identifies Protein Synthesis Inhibitors as H-Ras-Nanocluster-Increasing Tumor Growth Inducers.

Ras isoforms H-, N-, and K-ras are each mutated in specific cancer types at varying frequencies and have different activities in cell fate control. On the plasma membrane, Ras proteins are laterally segregated into isoform-specific nanoscale signaling hubs, termed nanoclusters. As Ras nanoclusters are required for Ras signaling, chemical modulators of nanoclusters represent ideal candidates for the specific modulation of Ras activity in cancer drug development. We therefore conducted a chemical screen with commercial and in-house natural product libraries using a cell-based H-ras-nanoclustering FRET assay. Next to established Ras inhibitors, such as a statin and farnesyl-transferase inhibitor, we surprisingly identified five protein synthesis inhibitors as positive regulators. Using commonly employed cycloheximide as a representative compound, we show that protein synthesis inhibition increased nanoclustering and effector recruitment specifically of active H-ras but not of K-ras. Consistent with these data, cycloheximide treatment activated both Erk and Akt kinases and specifically promoted H-rasG12V-induced, but not K-rasG12V-induced, PC12 cell differentiation. Intriguingly, cycloheximide increased the number of mammospheres, which are enriched for cancer stem cells. Depletion of H-ras in combination with cycloheximide significantly reduced mammosphere formation, suggesting an exquisite synthetic lethality. The potential of cycloheximide to promote tumor cell growth was also reflected in its ability to increase breast cancer cell tumors grown in ovo. These results illustrate the possibility of identifying Ras-isoform-specific modulators using nanocluster-directed screening. They also suggest an unexpected feedback from protein synthesis inhibition to Ras signaling, which might present a vulnerability in certain tumor cell types.

Linezolid-Associated Serotonin Syndrome. A Report of Two Cases.

Linezolid, a mild monoamine oxidase inhibitor, is a commonly used antibiotic drug for the treatment of complicated skin and skin structure infections, including diabetic foot infections. Use of linezolid has been associated with serotonin syndrome, a potentially life-threatening condition typically caused by the combination of two or more medications with serotonergic properties, due to increased serotonin release. The goals of this article are to highlight the risk factors associated with the development of serotonin syndrome related to the use of linezolid and to aid in its prevention and early diagnosis. In this case series we report on two hospitalized patients who, while being treated with linezolid for pedal infections, developed serotonin syndrome. Both individuals were also undergoing treatment with at least one serotonergic agent for depression and had received this medication within 2 weeks of starting the antibiotic drug therapy. In these individuals, we noted agitation, confusion, tremors, and tachycardia within a few days of initiation of linezolid therapy. Owing to the risk of serotonin toxicity, care should be taken when prescribing linezolid in conjunction with any other serotonergic agent. Although serotonin syndrome is an infrequent complication, it can be potentially life threatening. Therefore, risks and benefits of therapy should be weighed before use.

Ethanol at low concentrations protects glomerular podocytes through alcohol dehydrogenase and 20-HETE.

Clinical studies suggest cardiovascular and renal benefits of ingesting small amounts of ethanol. Effects of ethanol, role of alcohol dehydrogenase (ADH) or of 20-hydroxyeicosatetraenoic acid (20-HETE) in podocytes of the glomerular filtration barrier have not been reported. We found that mouse podocytes at baseline generate 20-HETE and express ADH but not CYP2e1. Ethanol at high concentrations altered the actin cytoskeleton, induced CYP2e1, increased superoxide production and inhibited ADH gene expression. Ethanol at low concentrations upregulated the expression of ADH and CYP4a12a. 20-HETE, an arachidonic acid metabolite generated by CYP4a12a, blocked the ethanol-induced cytoskeletal derangement and superoxide generation. Ethanol at high concentration or ADH inhibitor increased glomerular albumin permeability in vitro. 20-HETE and its metabolite produced by ADH activity, 20-carboxy-arachidonic acid, protected the glomerular permeability barrier against an ADH inhibitor, puromycin or FSGS permeability factor. We conclude that ADH activity is required for glomerular function, 20-HETE is a physiological substrate of ADH in podocytes and that podocytes are useful biosensors to understand glomeruloprotective effects of ethanol.

Antibacterial activity of new oxazolidin-2-one analogues in methicillin-resistant Staphylococcus aureus strains.

Staphylococcus aureus is one of the most common causes of nosocomial infections. The purpose of this study was the synthesis and in vitro evaluation of antimicrobial activity of 10 new 3-oxazolidin-2-one analogues on 12 methicillin resistant S. aureus (MRSA) clinical isolates. S. aureus confirmation was achieved via catalase and coagulase test. Molecular characterization of MRSA was performed by amplification of the mecA gene. Antimicrobial susceptibility was evaluated via the Kirby-Bauer disc diffusion susceptibility test protocol, using commonly applied antibiotics and the oxazolidinone analogues. Only (R)-5-((S)-1-dibenzylaminoethyl)-1,3-oxazolidin-2-one (7a) exhibited antibacterial activity at 6.6 µg. These results, allow us to infer that molecules such as 7a can be potentially used to treat infections caused by MRSA strains.

Designer aminoglycosides that selectively inhibit cytoplasmic rather than mitochondrial ribosomes show decreased ototoxicity: a strategy for the treatment of genetic diseases.

There is compelling evidence that aminoglycoside (AG) antibiotics can induce the mammalian ribosome to suppress disease-causing nonsense mutations and partially restore the expression of functional proteins. However, prolonged AG treatment can cause detrimental side effects in patients, including most prominently, ototoxicity. Recent mechanistic discussions have considered the relative contributions of mitochondrial and cytoplasmic protein synthesis inhibition to AG-induced ototoxicity. We show that AGs inhibit mitochondrial protein synthesis in mammalian cells and perturb cell respiration, leading to a time- and dose-dependent increase in superoxide overproduction and accumulation of free ferrous iron in mitochondria caused by oxidative damage of mitochondrial aconitase, ultimately leading to cell apoptosis via the Fenton reaction. These deleterious effects increase with the increased potency of AG to inhibit the mitochondrial rather than cytoplasmic protein synthesis, which in turn correlates with their ototoxic potential in both murine cochlear explants and the guinea pig in vivo. The deleterious effects of AGs were alleviated in synthetic derivatives specially designed for the treatment of genetic diseases caused by nonsense mutations and possessing low affinity toward mitochondrial ribosomes. This work highlights the benefit of a mechanism-based drug redesign strategy that can maximize the translational value of "readthrough therapy" while mitigating drug-induced side effects. This approach holds promise for patients suffering from genetic diseases caused by nonsense mutations.

Phase 2 study of subcutaneous omacetaxine mepesuccinate for chronic-phase chronic myeloid leukemia patients resistant to or intolerant of tyrosine kinase inhibitors.

Omacetaxine mepesuccinate (omacetaxine) is a first-in-class cephalotaxine with a unique mode of action, independent of BCR-ABL, that has shown promising activity in patients with chronic myeloid leukemia (CML). This multicenter, noncomparative, open-label phase 2 study evaluated the efficacy and safety of subcutaneous omacetaxine in CML patients with resistance or intolerance to two or more tyrosine kinase inhibitors (TKIs); results in patients in chronic phase are reported here. Patients received subcutaneous omacetaxine 1.25 mg/m² twice daily days 1-14 every 28 days until hematologic response (up to a maximum of six cycles), then days 1-7 every 28 days as maintenance. Primary endpoints were rates of hematologic response lasting >8 weeks and major cytogenetic response (MCyR). Forty-six patients were enrolled: all had received imatinib, 83% had received dasatinib, and 57% nilotinib. A median 4.5 cycles of omacetaxine were administered (range, 1-36). Hematologic response was achieved or maintained in 31 patients (67%); median response duration was 7.0 months. Ten patients (22%) achieved MCyR, including 2 (4%) complete cytogenetic responses. Median progression-free survival was 7.0 months [95% confidence interval (CI), 5.9-8.9 months], and overall survival was 30.1 months (95% CI, 20.3 months-not reached). Grade 3/4 hematologic toxicity included thrombocytopenia (54%), neutropenia (48%), and anemia (33%). Nonhematologic adverse events were predominantly grade 1/2 and included diarrhea (44%), nausea (30%), fatigue (24%), pyrexia (20%), headache (20%), and asthenia (20%). Subcutaneous omacetaxine may offer clinical benefit to patients with chronic-phase CML with resistance or intolerance to multiple TKI therapies.

[Protective effect of selank on the model of mnestic function violation induced by pharmacological blockade of protein synthesis].

We have studied the ability of peptide anxiolytic selank (Thr-Lyz-Pro-Arg-Pro-Gly-Pro) to compensate for mnestic dysfunction caused by the administration of actinomycin D, which inhibits protein synthesis by blocking DNA-dependent RNA polymerase. The experiments were performed on white rats with acquired adaptive ability of spatial visual orientation in a 16-door labyrinth. The learning was based on the avoidance of electric skin irritation at alternating sites of escape reaction (site reflex). Selank (0.5 mg/kg, i.p.) prevented or compensated for actinomycin D (250 mg/kg, i.p.) induced violation of the process of acquisition, improvement, and consolidation of memory trace during the development of a complex site reflex. The drug administration also reduced the time required for acquisition of the adaptive ability of spatial visual orientation in the labyrinth and restored the actinomycin D violated process of re-learning upon a change in the alternation of escape sites under free-choice conditions.

Mitochondrial ribosome and Ménière's disease: a pilot study.

Ménière's disease patients experience vestibular disability. When most of medical treatments fail, a chemical labyrinthectomy using aminoglycosides is indicated. However, this process frequently causes hearing damage. Aminoglycosides, interacting with mitochondrial rRNAs, alter mitochondrial protein synthesis and the oxidative phosphorylation system, which provide most of the energy in sensory hair cells. For this reason, we hypothesized that genetic variation in mitochondrial rRNA genes and in two nuclear genes coding for proteins that also modify the susceptibility to aminoglycosides might affect the risk of hearing loss in Ménière's disease patients suffering chemical labyrinthectomy. However, there were no differences in mitochondrial rRNA, TFB1M or MRPS12 genetic variation between those patients that experienced or did not experience hearing loss. This is only a pilot study and larger studies are required to use this therapeutic approach in a rational way and decrease the risk of hearing damage.

'PREHAB': Vestibular prehabilitation to ameliorate the effect of a sudden vestibular loss.

A sudden unilateral loss or impairment of vestibular function causes vertigo, dizziness and impaired postural function. In most occasions, everyday activities supported or not by vestibular rehabilitation programs will promote compensation and the symptoms subside. As the compensatory process requires sensory input, matching performed motor activity, both motor learning of exercises and matching to sensory input are required. If there is a simultaneous cerebellar lesion found during surgery of the posterior cranial fossa, there may be a risk of a combined vestibulo-cerebellar lesion, with reduced compensatory abilities and with prolonged or sometimes permanent disability. On the other hand, a slow gradual loss of unilateral function occurring as the subject continues well everyday activities may go without any prominent symptoms. We therefore implemented a pre treatment plan before planned vestibular lesions (prehab). This was first done in subject undergoing gentamicin treatment for Meniere's disease (MD). Subjects perform vestibular exercises for 14 days before the first gentamicin installation and then continue doing so until free of symptoms. Most subjects would only experience slight dizziness while losing vestibular function. We then expanded the approach to patients with brainstem tumours requiring surgery but with remaining vestibular function to ease postoperative symptoms and reduce risk of combined cerebello-vestibular lesions. This patient group was given gentamicin installations trans-tympanically before tumour sugary and then underwent prehab. In all cases there was a caloric loss, loss of VOR evident in the head impulse tests, impaired subjective vertical and horizontal, and reduced caloric function induced by the pre-surgery gentamicin treatment. The prehab eliminated spontaneous and positional nystagmus, subjective symptoms, and postural function up before surgery and allowed for rapid postoperative recovery.The concept of 'pre-lesion rehabilitation' where training is introduced before a planned lesion and if possible paralleled with a gradual function loss expands the potential of rehabilitation. Here it was used for vestibular lesions but it is possible that similar approaches may be developed for other situations, which include foreseeable loss of function.