Ototoxicity: a high risk to auditory function that needs to be monitored in drug development.

Hearing loss constitutes a major global health concern impacting approximately 1.5 billion people worldwide. Its incidence is undergoing a substantial surge with some projecting that by 2050, a quarter of the global population will experience varying degrees of hearing deficiency. Environmental factors such as aging, exposure to loud noise, and the intake of ototoxic medications are implicated in the onset of acquired hearing loss. Ototoxicity resulting in inner ear damage is a leading cause of acquired hearing loss worldwide. This could be minimized or avoided by early testing of hearing functions in the preclinical phase of drug development. While the assessment of ototoxicity is well defined for drug candidates in the hearing field - required for drugs that are administered by the otic route and expected to reach the middle or inner ear during clinical use - ototoxicity testing is not required for all other therapeutic areas. Unfortunately, this has resulted in more than 200 ototoxic marketed medications. The aim of this publication is to raise awareness of drug-induced ototoxicity and to formulate some recommendations based on available guidelines and own experience. Ototoxicity testing programs should be adapted to the type of therapy, its indication (targeting the ear or part of other medications classes being potentially ototoxic), and the number of assets to test. For multiple molecules and/or multiple doses, screening options are available: in vitro (otic cell assays), ex vivo (cochlear explant), and in vivo (in zebrafish). In assessing the ototoxicity of a candidate drug, it is good practice to compare its ototoxicity to that of a well-known control drug of a similar class. Screening assays provide a streamlined and rapid method to know whether a drug is generally safe for inner ear structures. Mammalian animal models provide a more detailed characterization of drug ototoxicity, with a possibility to localize and quantify the damage using functional, behavioral, and morphological read-outs. Complementary histological measures are routinely conducted notably to quantify hair cells loss with cochleogram. Ototoxicity studies can be performed in rodents (mice, rats), guinea pigs and large species. However, in undertaking, or at the very least attempting, all preclinical investigations within the same species, is crucial. This encompasses starting with pharmacokinetics and pharmacology efficacy studies and extending through to toxicity studies. In life read-outs include Auditory Brainstem Response (ABR) and Distortion Product OtoAcoustic Emissions (DPOAE) measurements that assess the activity and integrity of sensory cells and the auditory nerve, reflecting sensorineural hearing loss. Accurate, reproducible, and high throughput ABR measures are fundamental to the quality and success of these preclinical trials. As in humans, in vivo otoscopic evaluations are routinely carried out to observe the tympanic membrane and auditory canal. This is often done to detect signs of inflammation. The cochlea is a tonotopic structure. Hair cell responsiveness is position and frequency dependent, with hair cells located close to the cochlea apex transducing low frequencies and those at the base transducing high frequencies. The cochleogram aims to quantify hair cells all along the cochlea and consequently determine hair cell loss related to specific frequencies. This measure is then correlated with the ABR & DPOAE results. Ototoxicity assessments evaluate the impact of drug candidates on the auditory and vestibular systems, de-risk hearing loss and balance disorders, define a safe dose, and optimize therapeutic benefits. These types of studies can be initiated during early development of a therapeutic solution, with ABR and otoscopic evaluations. Depending on the mechanism of action of the compound, studies can include DPOAE and cochleogram. Later in the development, a GLP (Good Laboratory Practice) ototoxicity study may be required based on otic related route of administration, target, or known potential otic toxicity.

Detecting Central Auditory Processing Disorders in Awake Mice.

Mice are increasingly used as models of human-acquired neurological or neurodevelopmental conditions, such as autism, schizophrenia, and Alzheimer's disease. All these conditions involve central auditory processing disorders, which have been little investigated despite their potential for providing interesting insights into the mechanisms behind such disorders. Alterations of the auditory steady-state response to 40 Hz click trains are associated with an imbalance between neuronal excitation and inhibition, a mechanism thought to be common to many neurological disorders. Here, we demonstrate the value of presenting click trains at various rates to mice with chronically implanted pins above the inferior colliculus and the auditory cortex for obtaining easy, reliable, and long-lasting access to subcortical and cortical complex auditory processing in awake mice. Using this protocol on a mutant mouse model of autism with a defect of the Shank3 gene, we show that the neural response is impaired at high click rates (above 60 Hz) and that this impairment is visible subcortically-two results that cannot be obtained with classical protocols for cortical EEG recordings in response to stimulation at 40 Hz. These results demonstrate the value and necessity of a more complete investigation of central auditory processing disorders in mouse models of neurological or neurodevelopmental disorders.

Impulse Noise Induced Hidden Hearing Loss, Hair Cell Ciliary Changes and Oxidative Stress in Mice.

Recent studies demonstrated that reversible continuous noise exposure may induce a temporary threshold shift (TTS) with a permanent degeneration of auditory nerve fibers, although hair cells remain intact. To probe the impact of TTS-inducing impulse noise exposure on hearing, CBA/J Mice were exposed to noise impulses with peak pressures of 145 dB SPL. We found that 30 min after exposure, the noise caused a mean elevation of ABR thresholds of ~30 dB and a reduction in DPOAE amplitude. Four weeks later, ABR thresholds and DPOAE amplitude were back to normal in the higher frequency region (8-32 kHz). At lower frequencies, a small degree of PTS remained. Morphological evaluations revealed a disturbance of the stereociliary bundle of outer hair cells, mainly located in the apical regions. On the other hand, the reduced suprathreshold ABR amplitudes remained until 4 weeks later. A loss of synapse numbers was observed 24 h after exposure, with full recovery two weeks later. Transmission electron microscopy revealed morphological changes at the ribbon synapses by two weeks post exposure. In addition, increased levels of oxidative stress were observed immediately after exposure, and maintained for a further 2 weeks. These results clarify the pathology underlying impulse noise-induced sensory dysfunction, and suggest possible links between impulse-noise injury, cochlear cell morphology, metabolic changes, and hidden hearing loss.

N-acetylcysteine Treatment Reduces Age-related Hearing Loss and Memory Impairment in the Senescence-Accelerated Prone 8 (SAMP8) Mouse Model.

Age-related hearing loss (ARHL) is the most common sensory disorder in the elderly population. SAMP8 mouse model presents accelerated senescence and has been identified as a model of gerontological research. SAMP8 displays a progressive age-related decline in brain function associated with a progressive hearing loss mimicking human aging memory deficits and ARHL. The molecular mechanisms associated with SAMP8 senescence process involve oxidative stress leading to chronic inflammation and apoptosis. Here, we studied the effect of N-acetylcysteine (NAC), an antioxidant, on SAMP8 hearing loss and memory to determine the potential interest of this model in the study of new antioxidant therapies. We observed a strong decrease of auditory brainstem response thresholds from 45 to 75 days of age and an increase of distortion product amplitudes from 60 to 75 days in NAC treated group compared to vehicle. Moreover, NAC treated group presented also an increase of memory performance at 60 and 105 days of age. These results confirm that NAC delays the senescence process by slowing the age-related hearing loss, protecting the cochlear hair cells and improving memory, suggesting that antioxidants could be a pharmacological target for age-related hearing and memory loss.

Senescence-accelerated mouse prone 8 (SAMP8) as a model of age-related hearing loss.

Hearing loss is the most common form of sensory impairment in humans, affecting 5.3% worldwide population. In industrial countries, age-related hearing loss is a major health problem affecting one-third of individuals over 65years old. However, the physiological and molecular changes involved in this senescence process remain unclear. In this study, we determined the influence of age on auditory brainstem response (ABR) and the distortion product otoacoustic emissions (DPOAE) in the premature senescence mouse model SAMP8 for five months. We showed a progressive increase of ABR thresholds and a decrease of distortion product amplitude from 37days old in SAMP8 compared to CBA mice. The data we show here provide new knowledge in functional auditory changes during the senescence process and open up new opportunities for the development of new drugs involved in age-related hearing loss treatment.

The multinational second Diabetes, Attitudes, Wishes and Needs study: results of the French survey.

AIM: The second Diabetes, Attitudes, Wishes and Needs (DAWN2™) multinational cross-sectional study was aimed at generating insights to facilitate innovative efforts by people with diabetes (PWD), family members (FMs), and health care professionals (HCPs) to improve self-management and psychosocial support in diabetes. Here, the French data from the DAWN2™ study are described. METHODS: In France, 500 PWD (80 with type 1 diabetes [T1] and 420 with type 2 diabetes [T2]), 120 FMs, and 288 HCPs were recruited. The questionnaires assessed the impact of diabetes on quality of life and mood, self-management, attitudes/beliefs, and care/support. RESULTS: Diabetes negatively impacted the emotional well-being of 59% of people with T1 versus 45% of people with T2 (P<0.05) and about half of FMs. A high level of distress was felt by about half of PWD and FMs. About half of HCPs reported assessing depression in their patients. Sixty-two percent of FMs considered managing diabetes to be a burden. Hypoglycemia was a source of concern for 64% of people with T1 and 73% of FMs of insulin users. About two-thirds of non-insulin-medicated people with T2 agreed to start insulin if prescribed, while half of HCPs preferred to delay insulin initiation. A discrepancy between HCPs' perceptions of their interactions with their patients and PWD's recollection of these interactions with regard to patients' personal needs and distress was also observed. CONCLUSION: While distress remains under-assessed by HCPs, the negative impact of diabetes on the lives of PWD and FMs clearly induces distress on both groups. These findings provide new understanding of barriers precluding optimal management of diabetes. Developing strategies to overcome these barriers is now warranted.

SAR103168: a tyrosine kinase inhibitor with therapeutic potential in myeloid leukemias.

SAR103168, a tyrosine kinase inhibitor of the pyrido [2,3-d] pyridimidine subclass, inhibited the kinase activities of the entire Src kinase family, Abl kinase, angiogenic receptor kinases (vascular endothelial growth factor receptor [VEGFR] 1 and 2), Tie2, platelet derived growth factor (PDGF), fibroblast growth factor receptor (FGFR) 1 and 3, and epidermal growth factor receptor (EGFR). SAR103168 was a potent Src inhibitor, with 50% inhibitory concentration (IC50) = 0.65 ± 0.02 nM (at 100 µM ATP), targeting the auto-phosphorylation of the kinase domain (Src(260-535)) and activity of the phosphorylated kinase. Phosphorylation of Src, Lyn and Src downstream signaling pathways (PYK2, P-130CAS, FAK, JNK and MAPK) were inhibited in a dose-dependent manner. SAR103168 inhibited the phosphorylation of STAT5 in KG1 cells and fresh cells from patients with acute myeloid leukemia (AML). SAR103168 inhibited proliferation and induced apoptosis in acute and chronic myeloid leukemic cells at nanomolar IC50. SAR103168 induced anti-proliferation of leukemic progenitors (CFU-L) from 29 patients with AML, and > 85% of AML patient samples were sensitive to SAR103168. These antagonist activities of SAR103168 were independent of FLT3 expression. SAR103168 treatment was effective in 50% of high-risk patient samples carrying chromosome 7 abnormalities or complex rearrangement. SAR103168 administration (intravenous or oral) impaired tumor growth and induced tumor regression in animals bearing human AML leukemic cells, correlating with potent inhibition of Src downstream signaling pathways in AML tumors. SAR103168 showed potent anti-tumor activity in SCID (severe combined immunodeficiency) mice bearing AML (KG1, EOL-1, Kasumi-1, CTV1) and chronic myeloid leukemia (CML) (K562) tumors. The combination of cytarabine and SAR103168 showed synergistic activity in AML and CML tumor models. These results highlight the therapeutic potential of SAR103168 in myeloid leukemias and support the rationale for clinical investigations.

Very long-term follow-up of living kidney donors.

Knowledge of the very long-term consequences of kidney donors has not been previously reported extensively. The 398 persons who had donated a kidney between 1952 and 2008 at Necker hospital were contacted. Among the 310 donors who were located, the survival probabilities for this population were similar to those of the general population and end stage renal disease incidence was 581 per million population per year. All located donors still alive were asked to complete a medico-psychosocial questionnaire and give samples for serum creatinine and urinary albumin assays. Among the 204 donors who responded to the questionnaire, mean eGFR was 64.4±14.6ml/min per 1.73m(2) and mean microalbuminuria was 27.0±83mg/g. Most donors never regretted the donation and consider that it has no impact on their professional or social lives. Among the 59 donors who gave a kidney more than 30years ago (mean 40.2years, range 30-48years) had a mean eGFR of 67.5±17.4µmol/l, a mean microalbuminuria level of 44.8±123.2mg/g and none was dialyzed. In conclusion, living kidney donation does not impact survival, kidney function, medical condition or psychological or social status over the very long-term.

In vivo and in vitro antiarrhythmic effects of SSR149744C in animal models of atrial fibrillation and ventricular arrhythmias.

SSR149744C (2-butyl-3-{4-[3-(dibutylamino)propyl]benzoyl}-1-benzofuran-5-carboxylate isopropyl fumarate) is a new noniodinated benzofuran derivative structurally related to amiodarone and dronedarone that is currently undergoing clinical trials as an antiarrhythmic agent. As SSR149744C exhibits electrophysiological and hemodynamic properties of class I, II, III, and IV antiarrhythmic agents, the aim of this study was to evaluate its acute intravenous (IV) or oral (PO) antiarrhythmic activities in in vitro and in vivo animal models of atrial and ventricular arrhythmias. In vagally induced atrial fibrillation (AF) in anesthetized dogs, SSR149744C (3 and 10 mg/kg IV) terminated AF in all 7 dogs and prevented reinduction in 4 out of 7 dogs; effective refractory periods of right atrium were dose-dependently and frequency-independently lengthened. In low-K+ medium-induced AF models, SSR149744C (0.1 to 1 microM) prevented AF in isolated guinea pig hearts in a concentration-dependent manner. At the ventricular level, SSR149744C (0.1 to 10 mg/kg IV and 3 to 90 mg/kg PO) prevented reperfusion-induced arrhythmias in anesthetized rats with a dose-effect relationship, and, at doses of 30 to 90 mg/kg PO, it reduced early (0-24 hours) mortality following permanent left coronary artery ligature in conscious rats. The present results show that SSR149744C is an effective antiarrhythmic agent in atrial fibrillation and in ventricular arrhythmias. Like amiodarone and dronedarone, its efficiency in these animal models of arrhythmias is likely be related to its multifactorial mechanism of action.

Involvement of nitric oxide in amiodarone- and dronedarone-induced coronary vasodilation in guinea pig heart.

Amiodarone, a powerful antiarrhythmic compound, possesses coronary and peripheral vasodilator properties. The mechanisms responsible for these effects remain incompletely understood. In the present study, the coronary effects of amiodarone and dronedarone, a non-iodinated amiodarone-like compound, were investigated in isolated guinea pig hearts perfused at constant flow with high K+ solution (40 mM). Amiodarone (0.01-10 microM), dronedarone (0.01-1 microM) and verapamil (0.01-10 microM) induced concentration-dependent decreases in coronary perfusion pressure. Amiodarone- and dronedarone-mediated reductions in coronary perfusion pressure were not modified by a cyclooxygenase inhibitor, indomethacin (3 microM). L-Nitro-L-arginine (L-NOARG; 3-100 microM) caused a rightward shift of concentration-response curves to amiodarone and dronedarone in a dose-dependent way; L-arginine, a nitric oxide (NO) precursor, reversed this effect. Furthermore, when guinea pigs were treated with NG-nitro-L-arginine methyl ester (L-NAME; 20 mg/kg), amiodarone could not reduce coronary perfusion pressure. NO synthase inhibition did not affect the coronary perfusion pressure response to verapamil. 1H-[1,2,4]Oxadiazole (4,3-a) quinoxalin-1-one (ODQ), a specific inhibitor of the guanylyl cyclase, inhibited the effects of amiodarone but not those of verapamil. In the presence of L-NOARG and ODQ, and in hearts from animals treated with L-NAME, a decrease in coronary perfusion pressure was still observed at the highest concentration of dronedarone. These results show that, in guinea pig hearts, the coronary vasodilation induced by amiodarone highly depends on nitric oxide. Dronedarone differs from amiodarone by a remaining relaxant effect, refractory to inhibition of NO synthase pathway, probably due to its Ca+ antagonist properties.

Do health causal attributions and coping strategies act as moderators of quality of life in peritoneal dialysis patients?

OBJECTIVE: The present study aimed at testing the relationships between health causal attribution and coping mechanisms with quality of life (QOL) in patients who have end-stage renal disease (ESRD) undergoing a peritoneal dialysis (PD) treatment. It was hypothesized that QOL should be negatively associated with the severity of the disease. Problem-focused coping, internal health-related locus of control (HRLOC) and medical power HRLOC were hypothesized as positive moderators preserving a better QOL, after controlling for the severity of the disease. METHODS: A total of 47 PD patients completed the Kidney Disease Quality of Life (KD-QOL) scale encompassing the Medical Outcomes Study Short-Form (MOS SF-36) self-administered questionnaire, the Multidimensional Health Locus of Control scale and the Ways of Coping Check-List (WCCL) scale. RESULTS: Low scores for all QOL scores were found except for pain dimension, as compared with scores available from a general French population. Globally, QOL was not related to the severity of the disease. Univariate analysis showed that the physical component score (PCS) of QOL was positively associated with internal HRLOC (r=.35; P<.05), and negatively with medical power HRLOC (r=-.36; P<.05). Multivariate analysis adjusting for age confirmed these results. Mental component score (MCS) was negatively associated with the use of emotion-focused coping and seeking social support (r=-.45; P=.001 and r=-.30; P<.05, respectively), the first association persisting in multivariate analysis. Neither PCS nor MCS was linked to the use of problem-focused coping. CONCLUSION: These results suggest that physical QOL is all the more preserved when patients are more convinced that their behaviour can influence their health condition and that psychological QOL is all the more impaired when health condition is perceived as less controllable, requiring emotion-focused coping (avoidance strategies). Health causal attributions and coping act respectively as moderators of physical and psychological components of QOL.