Age-related changes in the zebrafish and killifish inner ear and lateral line.

Age-related hearing loss (ARHL) is a debilitating disorder for millions worldwide. While there are multiple underlying causes of ARHL, one common factor is loss of sensory hair cells. In mammals, new hair cells are not produced postnatally and do not regenerate after damage, leading to permanent hearing impairment. By contrast, fish produce hair cells throughout life and robustly regenerate these cells after toxic insult. Despite these regenerative abilities, zebrafish show features of ARHL. Here, we show that aged zebrafish of both sexes exhibited significant hair cell loss and decreased cell proliferation in all inner ear epithelia (saccule, lagena, utricle). Ears from aged zebrafish had increased expression of pro-inflammatory genes and significantly more macrophages than ears from young adult animals. Aged zebrafish also had fewer lateral line hair cells and less cell proliferation than young animals, although lateral line hair cells still robustly regenerated following damage. Unlike zebrafish, African turquoise killifish (an emerging aging model) only showed hair cell loss in the saccule of aged males, but both sexes exhibit age-related changes in the lateral line. Our work demonstrates that zebrafish exhibit key features of auditory aging, including hair cell loss and increased inflammation. Further, our finding that aged zebrafish have fewer lateral line hair cells yet retain regenerative capacity, suggests a decoupling of homeostatic hair cell addition from regeneration following acute trauma. Finally, zebrafish and killifish show species-specific strategies for lateral line homeostasis that may inform further comparative research on aging in mechanosensory systems.

Putative COVID-19 therapies imatinib, lopinavir, ritonavir, and ivermectin cause hair cell damage: A targeted screen in the zebrafish lateral line.

The biomedical community is rapidly developing COVID-19 drugs to bring much-need therapies to market, with over 900 drugs and drug combinations currently in clinical trials. While this pace of drug development is necessary, the risk of producing therapies with significant side-effects is also increased. One likely side-effect of some COVID-19 drugs is hearing loss, yet hearing is not assessed during preclinical development or clinical trials. We used the zebrafish lateral line, an established model for drug-induced sensory hair cell damage, to assess the ototoxic potential of seven drugs in clinical trials for treatment of COVID-19. We found that ivermectin, lopinavir, imatinib, and ritonavir were significantly toxic to lateral line hair cells. By contrast, the approved COVID-19 therapies dexamethasone and remdesivir did not cause damage. We also did not observe damage from the antibiotic azithromycin. Neither lopinavir nor ritonavir altered the number of pre-synaptic ribbons per surviving hair cell, while there was an increase in ribbons following imatinib or ivermectin exposure. Damage from lopinavir, imatinib, and ivermectin was specific to hair cells, with no overall cytotoxicity noted following TUNEL labeling. Ritonavir may be generally cytotoxic, as determined by an increase in the number of TUNEL-positive non-hair cells following ritonavir exposure. Pharmacological inhibition of the mechanotransduction (MET) channel attenuated damage caused by lopinavir and ritonavir but did not alter imatinib or ivermectin toxicity. These results suggest that lopinavir and ritonavir may enter hair cells through the MET channel, similar to known ototoxins such as aminoglycoside antibiotics. Finally, we asked if ivermectin was ototoxic to rats in vivo. While ivermectin is not recommended by the FDA for treating COVID-19, many people have chosen to take ivermectin without a doctor's guidance, often with serious side-effects. Rats received daily subcutaneous injections for 10 days with a clinically relevant ivermectin dose (0.2 mg/kg). In contrast to our zebrafish assays, ivermectin did not cause ototoxicity in rats. Our research suggests that some drugs in clinical trials for COVID-19 may be ototoxic. This work can help identify drugs with the fewest side-effects and determine which therapies warrant audiometric monitoring.

Reducing mortality and infections after congenital heart surgery in the developing world.

BACKGROUND: There is little information about congenital heart surgery outcomes in developing countries. The International Quality Improvement Collaborative for Congenital Heart Surgery in Developing World Countries uses a registry and quality improvement strategies with nongovernmental organization reinforcement to reduce mortality. Registry data were used to evaluate impact. METHODS: Twenty-eight sites in 17 developing world countries submitted congenital heart surgery data to a registry, received annual benchmarking reports, and created quality improvement teams. Webinars targeted 3 key drivers: safe perioperative practice, infection reduction, and team-based practice. Registry data were audited annually; only verified data were included in analyses. Risk-adjusted standardized mortality ratios (SMRs) and standardized infection ratios among participating sites were calculated. RESULTS: Twenty-seven sites had verified data in at least 1 year, and 1 site withdrew. Among 15,049 cases of pediatric congenital heart surgery, unadjusted mortality was 6.3% and any major infection was 7.0%. SMRs for the overall International Quality Improvement Collaborative for Congenital Heart Surgery in Developing World Countries were 0.71 (95% confidence interval [CI] 0.62-0.81) in 2011 and 0.76 (95% CI 0.69-0.83) in 2012, compared with 2010 baseline. SMRs among 7 sites participating in all 3 years were 0.85 (95% CI 0.71-1.00) in 2011 and 0.80 (95% CI 0.66-0.96) in 2012; among 14 sites participating in 2011 and 2012, the SMR was 0.80 (95% CI 0.70-0.91) in 2012. Standardized infection ratios were similarly reduced. CONCLUSIONS: Congenital heart surgery risk-adjusted mortality and infections were reduced in developing world programs participating in the collaborative quality improvement project and registry. Similar strategies might allow rapid reduction in global health care disparities.

Mothers' attributions following their child's diagnosis of autistic spectrum disorder: exploring links with maternal levels of stress,depression and expectations about their child's future.

Although the impact of autism spectrum disorders (ASDs) on the family is well recognized, the way mothers attempt to make sense of the diagnosis is largely unexplored. However, in other disabilities, attributions have been shown to predict a variety of outcomes including maternal wellbeing and engagement in treatment. Using Weiner's (1985) three-dimensional model, 16 mothers were interviewed to examine the nature and impact of their beliefs about their child's ASD using semi-structured interviews and measures of depression, parenting stress and expectations for their child's future. The findings suggested that mothers made a diverse and complex range of attributions that were consistent with Weiner's dimensions of locus of cause, stability and controllability. The nature of their attributions reflected particular difficulties associated with ASDs, such as uncertainties regarding cause and prognosis. Taking account of mothers' search for meaning will better enable professionals to support families following diagnosis.