Hepatocyte nuclear factor-4 alpha in noise-induced cochlear neuropathy

Heterozygous recurrent HNF4A variant p.Arg85Trp causes Fanconi renotubular syndrome 4 with maturity onset diabetes of the young, an autosomal dominant phenocopy of Fanconi Bickel syndrome with colobomas

Heterozygous pathogenic variants in HNF4A cause hyperinsulinism, maturity onset diabetes of the young type 1, and more rarely Fanconi renotubular syndrome. Specifically, the recurrent missense pathogenic variant c.253C>T (p.Arg85Trp) has been associated with a syndromic form of hyperinsulinism with additional features of macrosomia, renal tubular nephropathy, hypophosphatemic rickets, and liver involvement. We present an affected mother, who had been previously diagnosed clinically with the autosomal recessive Fanconi Bickel Syndrome, and her affected son. The son's presentation expands the clinical phenotype to include multiple congenital anomalies, including penile chordee with hypospadias and coloboma. This specific pathogenic variant should be considered in the differential diagnosis of Fanconi Bickel Syndrome when genetics are negative or the family history is suggestive of autosomal dominant inheritance. The inclusion of hyperinsulinism and maturity onset of the diabetes of the young changes the management of this syndrome and the recurrence risk is distinct. Additionally, this family also emphasizes the importance of genetic confirmation of clinical diagnoses, especially in adults who grew up in the premolecular era that are now coming to childbearing age. Finally, the expansion of the phenotype to include multiple congenital anomalies suggests that the full spectrum of HNF4A is likely unknown.

MicroRNAs in Noise-Induced Hearing Loss and their Regulation by Oxidative Stress and Inflammation

Noise exposure (NE) has been recognized as one of the causes of sensorineural hearing loss (SNHL), which can bring about irreversible damage to sensory hair cells in the cochlea, through the launch of oxidative stress pathways and inflammation. Accordingly, determining the molecular mechanism involved in regulating hair cell apoptosis via NE is essential to prevent hair cell damage. However, the role of microRNAs (miRNAs) in the degeneration of sensory cells of the cochlea during NE has not been so far uncovered. Thus, the main purpose of this study was to demonstrate the regulatory role of miRNAs in the oxidative stress pathway and inflammation induced by NE. In this respect, articles related to noise-induced hearing loss (NIHL), oxidative stress, inflammation, and miRNA from various databases of Directory of Open Access Journals (DOAJ), Google Scholar, PubMed; Library, Information Science & Technology Abstracts (LISTA), and Web of Science were searched and retrieved. The findings revealed that several studies had suggested that up-regulation of miR-1229-5p, miR-451a, 185-5p, 186 and down-regulation of miRNA-96/182/183 and miR-30b were involved in oxidative stress and inflammation which could be used as biomarkers for NIHL. There was also a close relationship between NIHL and miRNAs, but further research is required to prove a causal association between miRNA alterations and NE, and also to determine miRNAs as biomarkers indicating responses to NE.

Otoprotective Effects of Stephania tetrandra S. Moore Herb Isolate against Acoustic Trauma

Noise is the most common occupational and environmental hazard, and noise-induced hearing loss (NIHL) is the second most common form of sensorineural hearing deficit. Although therapeutics that target the free-radical pathway have shown promise, none of these compounds is currently approved against NIHL by the United States Food and Drug Administration. The present study has demonstrated that tetrandrine (TET), a traditional Chinese medicinal alkaloid and the main chemical isolate of the Stephania tetrandra S. Moore herb, significantly attenuated NIHL in CBA/CaJ mice. TET is known to exert antihypertensive and antiarrhythmic effects through the blocking of calcium channels. Whole-cell patch-clamp recording from adult spiral ganglion neurons showed that TET blocked the transient Ca2+ current in a dose-dependent manner and the half-blocking concentration was 0.6 + 0.1 μM. Consistent with previous findings that modulations of calcium-based signaling pathways have both prophylactic and therapeutic effects against neural trauma, NIHL was significantly diminished by TET administration. Importantly, TET has a long-lasting protective effect after noise exposure (48 weeks) in comparison to 2 weeks after noise exposure. The otoprotective effects of TET were achieved mainly by preventing outer hair cell damage and synapse loss between inner hair cells and spiral ganglion neurons. Thus, our data indicate that TET has great potential in the prevention and treatment of NIHL.