[Effect of EGCG on H2O2-induced MnSOD gene expression in cultured spiral ganglion cells].

OBJECTIVE: To investigate the influence of EGCG on H2O2-induced gene expression of manganese superoxide dismutase (MnSOD or SOD2) in cultured spiral ganglion cells (SGCs) in vitro. METHODS: SGCs were cultured in vitro, and H2O2 and/or EGCG in different concentrations were used. Semi-quantitative RT-PCR was applied to observe MnSOD gene expression in SGCs after H2O2 and EGCG treatment. RESULTS: The expression of MnSOD gene was up-regulated with the increase of the concentration of H2O2 in cultured SGCs, and MnSOD gene expression was significantly up-regulated at a dose of H2O2 > or =100 micromol/L. However, this up-regulation was suppressed after simultaneously treated with 100 microg/ml EGCG. CONCLUSION: EGCG suppresses H2O2-induced up-regulation of MnSOD gene expression in cultured SGCs by getting rid of oxygen free radicals, reinforcing the activity of antioxidant enzymes such as MnSOD, and protects cultured SGCs from H2O2-induced oxidizing damage.

[Mutation screening in selected exons of myosin 7a gene in prelingual non-syndromic hearing impairment patients].

OBJECTIVE: To ascertain the frequency and characteristics of myosin 7a gene mutations in Chinese with prelingual nonsyndromic hearing impairment. METHODS: Most of cases were collected within Hunan province, including 31 sporadic congenital deaf patients and 65 patients from 34 hereditary prelingual deafness families, and 100 health individuals were used as control. Genomic DNA was extracted from the patients and subjected to the PCR to amplify selected exons of myosin 7a gene, and then the amplified products were screened for base variations by single strand conformational polymorphismanalysis (SSCP). The bands with abnormal conformation were sequenced to confirm the mutation. RESULTS: G to A substitution was detected at nucleotide 617 in exon 7 as hetrozygous state in two patients and was not found in unaffected members in their family. This mutation caused Arg206Gln within a highly conserved heptapeptide sequence of myosin 7a protein, and was close relevant to the prelingual nonsyndromic deafness. CONCLUSIONS: The Arg206Gln mutation in exon 7 of myosin 7a is possibly a novel mutation to cause prelingual nonsyndromic hearing impairment. Our results provide the evidence that exon 7 of Myosin 7a is a mutational hotspot region in genetic deafness.