Lipid Peroxidation and Ultrastructural Modifications in Brain after Perinatal Exposure to Lead and/or Cadmium in Rat Pups

Objective To assess lipid peroxidation and ultrastructural modifications in rat brains following perinatal exposure to lead （Pb） and/or cadmium （Cd）. Methods Female rats were divided into four groups： control group, Pb （300 mg/L） group, Cd group （10 mg/L） and Pb＋Cd （300 mg/L, 10 mg/L） group. The compounds were delivered in the drinking water throughout pregnancy and lactation. Results The levels of compounds in blood and brain of the Pb＋Cd group were similar to those of other groups, but the effects of Pb＋Cd on pups＇ body and brain weights were higher than on other compounds. Electron microscopy revealed that Pb and Cd had effects on mitochondrial swelling, disruption and cristae loss, Nissl body dissolution, degenerated organelles and vacuoles, cytomembrane disappearance, and nuclear chromoplasm concentration. The activity of glutathione peroxidase （GSH-Px）, superoxide dismutase （SOD）, catalase （CAT）, acetylcholinesterase （ACHE） was decreased, whereas the activity of maleic dialdehyde （MDA） was increased. Conclusion Perinatal exposure to low doses of Pb and Cd can produce alterations in lipid peroxidation and ultrastructural modifications in rat brains, and exposure to both metals can result in greater damages.

Imaging assessment of profound sensorineural deafness with inner ear anatomical abnormalities

Objective: : To explore the value of a combined computed tomography(CT) and magnetic resonance imaging(MRI) in evaluating profound sensorineural deafness patients before cochlear implant(CI) surgery.Methods: A retrospective analysis of 1012 cases of profound sensorineural deafness that received CI was performed.Results: A total of 96 cases were diagnosed with inner ear abnormalities including large vestibular aqueduct syndrome(LVAS, n ? 61), Michel deformity(n ? 3), cochlear incomplete partition I(n ? 2), cochlear incomplete partition II(n ? 6), cochlear hypoplasia with vestibular malformation(n ? 3), cochlear ossification(n ? 3), bilateral internal auditory canal obstruction(n ? 5) and internal auditory canal stenosis(n ? 2).Conclusion: High resolution CT(HRCT) can display bony structures while MRI can image the membranous labyrinth in preoperative evaluation for cochlear implantation. The combination of these two modalities provides reliable anatomical information regarding the bony and membranous labyrinths, as well as the auditory nerve.

The genetic basis of deafness in populations of African descent

Hearing loss is the most common sensorineural disorder worldwide and is associated with more than1000 mutations in more than 90 genes. While mutations in genes such as GJB2(gap-junction protein β 2)and GJB6(gap-junction protein β 6) are highly prevalent in Caucasian, Asian, and Middle Eastern populations, they are rare in both native African populations and those of African descent. The objective of this paper is to review the current knowledge regarding the epidemiology and genetics of hearing loss in African populations with a focus on native sub-Saharan African populations. Environmental etiologies related to poor access to healthcare and perinatal care account for the majority of cases. Syndromic etiologies including Waardenburg, Pendred and Usher syndromes are uncommon causes of hearing loss in these populations. Of the non-syndromic causes, common mutations in GJB2 and GJB6 are rarely implicated in populations of African descent. Recent use of next-generation sequencing(NGS) has identified several candidate deafness genes in African populations from Nigeria and South Africa that are unique when compared to common causative mutations worldwide. Researchers also recently described a dominant mutation in MYO3α in an African American family with non-syndromic hearing loss. The use of NGS and specialized panels will aid in identifying rare and novel mutations in a more cost-and timeeffective manner. The identification of common hearing loss mutations in indigenous African populations will pave the way for translation into genetic deafness research in populations of African descent worldwide.

Immunity Genes and Susceptibility to Otitis Media:A Comprehensive Review

Otitis media （OM） is a middle ear infection associated with inflammation and pain. This disease frequently afflicts humans and is the major cause of hearing loss worldwide. OM continues to be one of the most challenging diseases in the medical field due to its diverse host targets and wide range of clinical manifestations. Substantial morbidity associated with OM is further exacerbated by high frequency of recurrent infections leading to chronic suppurative otitis media （CSOM）. Children have greater susceptibility to, and thus, suffer most frequently from OM, which can cause significant deterioration in quality of life. Genetic factors have been demonstrated, in large part by twin and family studies, to be key determinants of OM susceptibility. In this review, we summarize the current knowledge on immunity genes and selected variants that have been associated with predisposition to OM. In particular, polymorphisms in innate immunity and cytokine genes have been strongly linked with the risk of developing OM. Future studies employing state-of-the-art technologies, including next-generation sequencing （NGS）, will aid in the identification of novel genes associated with susceptibility to OM. This, in turn, will open up avenues for identifying high-risk individuals and designing novel therapeutic strategies based on precise targeting of these genes.

Precision medicine in hearing loss

Precision medicine（PM） proposes customized medical care based on a patient＇s unique genome, biomarkers, environment and behaviors. Hearing loss（HL） is the most common sensorineural disorder worldwide and is frequently caused by a single genetic mutation. With recent advances in PM tools such as genetic sequencing and data analysis, the field of HL is ideally positioned to adopt the strategies of PM.Here, we review current and future applications of PM in HL as they relate to the four core qualities of PM（P4）： predictive, personalized, patient-centered, and participatory. We then introduce a strategy for effective incorporation of HL PM into the design of future research studies, electronic medical records,and clinical practice to improve diagnostics, prognostics, and, ultimately, individualized patient treatment. Finally, specific anticipated ethical and economic concerns in this growing era of genomics-based HL treatment are discussed. By integrating PM principles into translational HL research and clinical practice, hearing specialists are uniquely positioned to effectively treat the heterogeneous causes and manifestations of HL on an individualized basis.