Intracranial complication rates associated with cochlear implantation are low, although potentially very serious. Surgeons should be aware of intracranial complications, especially in older individuals, and take immediate appropriate action.
Otolaryngology residents report a high rate of sharps exposures during residency training, with a significant number of these exposures going unreported. Better education may be needed to help decrease these often preventable workplace exposures and to improve compliance with reporting and testing procedures.
Hypermethylation of CpG sites within the promoter region of the O 6 -methylguanine-DNA methyltransferase (MGMT) gene occurs frequently in human cancer, preventing both MGMT expression and repair of alkylation damage. To assess the role of MGMT in the development of mouse skin tumors induced by initiationpromotion protocols, methylation of the MGMT promoter was examined in tumor DNA using methylation-specific PCR. To determine whether MGMT promoter methylation was affected by the tumor induction protocol, tumors were initiated by N-methyl-N 0 -nitro-N-nitrosoguanidine (MNNG) or 7,12-dimethylbenz[a]anthracene (DMBA) and promoted by 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein. Although the MGMT promoter was not methylated in normal skin, promoter methylation was found in 56 of 136 papillomas (41.2%) and in 19 of 37 squamous cell carcinomas (51.4%). When methylation of the MGMT promoter was compared in the 4 treatment groups, hypermethylation was found more frequently in tumors initiated by DMBA and promoted by mezerein, a protocol associated with a high frequency of malignant conversion. Methylation was found in some tumors as early as 5 weeks after initiation, but the methylation frequency increased with time. MGMT promoter methylation reduced MGMT expression as determined by immunohistochemistry. Although MGMT promoter methylation was not generally correlated with ras mutations, the frequency of MGMT methylation was higher in MNNGinitiated, mezerein-promoted papillomas with mutations in Ha-ras compared to papillomas with Ki-ras. Methylation of the MGMT promoter, associated with reduced MGMT expression, is found in nearly half of mouse skin tumors, but varies with both the tumor initiator and tumor promoter, and may be a key step in the progression from papillomas to carcinomas. ' 2005 Wiley-Liss, Inc.Key words: methylation; MGMT; skin tumors; papillomas; carcinomas MNNG and other alkylating agents induce O 6 -alkylguanine DNA adducts that are important in tumor induction 1 and can be repaired by the DNA repair enzyme MGMT. MGMT irreversibly transfers the methyl group of O 6 -methylguanine to a specific cysteine residue within its own sequence, thereby restoring guanine and preventing G-A base substitutions. The level of MGMT per cell, which determines the rate of repair of O 6 -methylguanine, affects the susceptibility to the mutagenic and carcinogenic effects of alkylating carcinogens. 2-4 MGMT expression is reduced by hypermethylation of CpG islands within the promoter region of MGMT in primary human carcinomas 5 and in transformed human cell lines in culture. 6 Inactivation of the MGMT gene has been associated with G-A mutations in the Ki-ras oncogene 7 and the p53 tumor suppressor gene in human colorectal tumors. 8 The importance of MGMT in tumor development has been verified in studies using genetically-engineered MGMT transgenic and knockout mice. Overexpression of human or E. coli MGMT prevents G-A mutations and protects mice from tumorigenesis after treatment with alkylating agents. 9-11 Transg...
Objective To assess audiologic performance and quality of life in geriatric cochlear implantation patients and to determine whether comorbid medical conditions, etiology, and duration of hearing loss impact audiologic and quality of life outcomes. Methods Geriatric patients who underwent cochlear implantation between 1990 and 2006 were evaluated. Inclusion criteria were 55 years of age or older at time of implantation and post-lingual hearing loss. Patients with primary language other than English were excluded. 49 cochlear implant recipients were identified. A group of younger implanted patients was used as a control. All patients completed standardized audiologic tests including the Hearing In Noise Test. Validated surveys, including the Glasgow Benefit Inventory and the Hearing Handicap Inventory for the Elderly, were used to assess quality of life. Results The mean age at implantation was 69.5 (range 58–85) and the average time interval from the implantation to the completion of the surveys was 73.2 months (6 to 229). Identified comorbid conditions included hypertension, diabetes, and malignancies, among others. Audiologic performance and quality of life scores between the two groups were similar. In the geriatric group there was no difference in patient satisfaction between subgroups with 0–1, 2–3 or > 3 comorbid conditions. Conclusions Our results suggest that the audiologic performance and quality of life scores between the older and younger age groups are similar. In the geriatric group associated comorbidities did not interfere with patient satisfaction as assessed by survey instruments.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.