Oxidative stress and apoptotic changes of rat cerebral cortical neurons exposed to cadmium in vitro.

OBJECTIVE: To investigate the cytotoxic mechanism of cadmium (Cd) on cerebral cortical neurons. METHODS: The primary cultures of rat cerebral cortical neurons were treated with different concentrations of cadmium acetate (0, 5, 10, and 20 micromol/L), and then the cell viability, apoptosis, ultrastructure, intracellular [Ca2+], and reactive oxygen species (ROS) levels, mitochondrial membrane potential (delta psi), activities of catalase (CAT) and superoxide dismutase (SOD) were measured. RESULTS: A progressive loss in cell viability and an increased number of apoptotic cells were observed. In addition, Cd-induced apoptotic morphological changes in cerebral cortical neurons were also demonstrated by Hoechst 33258 staining. Meanwhile, ultrastructural changes were distortion of mitochondrial cristae and an unusual arrangement. Simultaneously, elevation of intracellular [Ca2+]i and ROS levels, depletion of Delta Psi were revealed in a dose-dependent manner during the exposure. Moreover, CAT and SOD activities in the living cells increased significantly. CONCLUSION: Exposure of cortical neurons to different doses of Cd led to cellular death, mediated by an apoptotic mechanism, and the apoptotic death induced by oxidative stress may be a potential reason. And the disorder of intracellular homeostasis caused by oxidative stress and mitochondrial dysfunction may be a trigger for apoptosis in cortical neurons.

Generation of hiPSC line UMi030-A from an individual with the hearing loss-related GJB2 mutation c.109G > A.

Genetic variants in the GJB2 gene which encodes for the Connexin 26 protein account for âˆ¼ 60% of cases of genetic hearing loss. A novel hiPSC line was generated from an individual with the hearing loss-related variant c.109G > A in GJB2 leading to the p.V37I alteration in the Connexin26 protein. These cells will help to delineate the role of GJB2 in hearing loss pathogenesis and serve as a platform for drug discovery and development.

Characterization of an induced pluripotent stem cell line (UMi040-A) bearing an auditory neuropathy spectrum disorder-associated variant in TMEM43.

Hearing loss is one of the most common sensory disorders. TMEM43 is expressed in cochlear glia-like supporting cells (GLSs) and is known to be associated with late-onset auditory neuropathy spectrum disorder (ANSD) and progressive hearing loss. Here, we describe the derivation of an induced pluripotent stem cell (iPSC) line from a patient lymphoblastoid cell line (LCL) carrying a single heterozygous nonsense variant (p.Arg372Ter (c.1114C > T)) in TMEM43 that leads to a truncated protein lacking the 4th transmembrane domain. This cell line can serve as a tool for disease modelling and development of therapeutic approaches to restore inner ear function.

Characterization of UMi028-A-1 stem cell line that contains a CRISPR/Cas9 induced hearing loss-associated variant (V60L (c.178G > T)) in the P2RX2 gene.

UMi028-A-1 hiPSC line contains a CRISPR/Cas9-induced heterozygous, hearing loss-associated variant (V60L (GTA > TTA)) in the Purinergic Receptor P2X2 (P2RX2) gene. This line, derived from an unaffected male iPSC line, has been successfully characterized for its cellular and genetic properties. The c.178G > T variant in P2RX2 is associated with non-syndromic, dominant, progressive hearing loss. Once differentiated into inner ear cell types, UMi028-A-1 will serve as a resource for understanding the molecular mechanisms underlying hearing loss and serve as a potential platform for testing therapeutic approaches to restore inner ear function.

Diagnostic and therapeutic applications of genomic medicine in progressive, late-onset, nonsyndromic sensorineural hearing loss.

The progressive, late-onset, nonsyndromic, sensorineural hearing loss (PNSHL) is the most common cause of sensory impairment globally, with presbycusis affecting greater than a third of individuals over the age of 65. The etiology underlying PNSHL include presbycusis, noise-induced hearing loss, drug ototoxicity, and delayed-onset autosomal dominant hearing loss (AD PNSHL). The objective of this article is to discuss the potential diagnostic and therapeutic applications of genomic medicine in PNSHL. Genomic factors contribute greatly to PNSHL. The heritability of presbycusis ranges from 25 to 75%. Current therapies for PNSHL range from sound amplification to cochlear implantation (CI). PNSHL is an excellent candidate for genomic medicine approaches as it is common, has well-described pathophysiology, has a wide time window for treatment, and is amenable to local gene therapy by currently utilized procedural approaches. AD PNSHL is especially suited to genomic medicine approaches that can disrupt the expression of an aberrant protein product. Gene therapy is emerging as a potential therapeutic strategy for the treatment of PNSHL. Viral gene delivery approaches have demonstrated promising results in human clinical trials for two inherited causes of blindness and are being used for PNSHL in animal models and a human trial. Non-viral gene therapy approaches are useful in situations where a transient biologic effect is needed or for delivery of genome editing reagents (such as CRISPR/Cas9) into the inner ear. Many gene therapy modalities that have proven efficacious in animal trials have potential to delay or prevent PNSHL in humans. The development of new treatment modalities for PNSHL will lead to improved quality of life of many affected individuals and their families.

Oxygen Saturation in Closed-Globe Blunt Ocular Trauma.

Purpose. To evaluate the oxygen saturation in retinal blood vessels in patients after closed-globe blunt ocular trauma. Design. Retrospective observational case series. Methods. Retinal oximetry was performed in both eyes of 29 patients with unilateral closed-globe blunt ocular trauma. Arterial oxygen saturation (SaO2), venous oxygen saturation (SvO2), arteriovenous difference in oxygen saturation (SO2), arteriolar diameter, venular diameter, and arteriovenous difference in diameter were measured. Association parameters including age, finger pulse oximetry, systolic pressure, diastolic pressure, and heart rate were analyzed. Results. The mean SaO2 in traumatic eyes (98.1% ± 6.8%) was not significantly different from SaO2 in unaffected ones (95.3% ± 7.2%) (p = 0.136). Mean SvO2 in traumatic eyes (57.1% ± 10.6%) was significantly lower than in unaffected ones (62.3% ± 8.4%) (p = 0.044). The arteriovenous difference in SO2 in traumatic eyes (41.0% ± 11.2%) was significantly larger than in unaffected ones (33.0% ± 6.9%) (p = 0.002). No significant difference was observed between traumatic eyes and unaffected ones in arteriolar (p = 0.249) and venular diameter (p = 0.972) as well as arteriovenous difference in diameter (p = 0.275). Conclusions. Oxygen consumption is increased in eyes after cgBOT, associated with lower SvO2 and enlarged arteriovenous difference in SO2 but not with changes in diameter of retinal vessels.

Using surgical microscope for sclera buckling and transscleral cryopexy: an alternative procedure of treatment for rhegmatogenous retinal detachment.

Purpose. To observe the long-term effectiveness of scleral buckling and transscleral cryopexy conducted under a surgical microscope in the treatment of uncomplicated rhegmatogenous retinal detachment. Methods. This was a retrospective analysis in a total of 227 consecutive patients (244 eyes) with uncomplicated rhegmatogenous retinal detachment (proliferative vitreoretinopathy ≤ C2). All patients underwent scleral buckling and transscleral cryopexy under a surgical microscope without using a binocular indirect ophthalmoscope or a contact lens. Results. After initial surgery, complete retinal reattachment was achieved in 226 eyes (92.6%), and retinal redetachment developed in 18 eyes (7.4%). The causes of retinal redetachment included presence of new breaks in eight eyes (44%), failure to completely seal the breaks in five eyes (28%), missed retinal breaks in four eyes (22%), and iatrogenic retinal breaks in one eye (6%). Scleral buckling surgery was performed again in 12 eyes (66%). Four eyes (22%) developed proliferative vitreoretinopathy and then were treated by vitrectomy. The sealing of retinal breaks and complete retinal reattachment were achieved in 241 eyes (98.8%). Conclusion. Probably because of clear visualization of retinal breaks and being controllable under a surgical microscope, the microsurgery of scleral buckling and transscleral cryopexy for uncomplicated retinal detachment exhibits advisable effectiveness.

Audioprofiles and antioxidant enzyme genotypes in presbycusis.

OBJECTIVES/HYPOTHESIS: Audiometric patterns have been shown to indirectly provide information regarding the pathophysiology of presbycusis and be useful in the phenotyping of hereditary deafness. STUDY DESIGN AND METHODS: Hospital-based cohort study of adults with presbycusis, comparing the association of audiometric patterns and polymorphisms of antioxidant enzymes that have been linked to presbycusis: GSTT1, GSTM1 and NAT2. All subjects underwent a clinical evaluation and completed questionnaires regarding ototoxicity and noise exposure. Pure-tone threshold audiometry was obtained and subjects' audiograms were classified into specific patterns. DNA was extracted from blood and the polymorphisms of GSTT1, GSTM1, and the NAT2 variants (NAT2* 5A; NAT2* 6A,B) were analyzed by PCR. RESULTS: The audiometric patterns that were more prevalent in our cohort were "High-Frequency Steeply Sloping" or HFSS (33%), "High-Frequency Gently Sloping" or HFGS (31%), and "Flat" (27%), with other patterns being rare. We did not find a statistical significant effect of gender, age, hearing level, and ear side on the audiometric pattern. Subjects with mutant alleles for GSTT1 were more likely to have a HFSS audiogram than subjects with the wild type genotype. CONCLUSIONS: In this cohort, there was a similar prevalence for the three audiometric configurations HFSS, HFGS, and Flat, with other configurations being rare. Subjects with mutant alleles for GSTT1 were more likely to have a HFSS audiogram than subjects with the wild type genotype, suggesting that the basal turn of the cochlea is susceptible to GSTT1 regulated oxidative stress. However, further studies of audioprofiles with larger sample sizes may be needed to establish phenotype-genotype correlations in presbycusis.