It is well known that the Epstein-Barr virus (EBV) contributes directly to tumourigenesis in nasopharyngeal carcinoma (NPC), primarily in the undifferentiated form of NPC (WHO type III; UNPC or UC), which is commonly found in South East Asia. Unfortunately, research in NPC has been severely hampered by the lack of authentic EBV-positive (EBV+) human NPC cell lines for study. Since 1975, there have been more than 20 reported NPC cell lines. However, many of these NPC-derived cell lines do not express EBV transcripts in long-term culture, and therefore that finding may dispute the fundamental theory of NPC carcinogenesis. In fact, currently only one EBV+ human NPC cell line (C-666) in long-term culture has been reported. Hence, most of the NPC cell lines may not be representative of the disease itself. In order to better understand and treat NPC, there is an urgent need to develop more EBV+ human NPC cell lines. In this review, we discuss the authenticity of existing NPC cell lines and the impact of our understanding of NPC biology on the treatment of the disease and the relationship of EBV to NPC in the context of cell lines.
Cell Line, Tumor ; virology ; Herpesvirus 4, Human ; pathogenicity ; Humans ; Nasopharyngeal Neoplasms ; physiopathology ; virology

OBJECTIVES: Radiotherapy for head and neck tumors is known to potentially induce sensorineural hearing loss, which is possibly due to damage to the cochlear and/or auditory pathways. Since the success of cochlear implantation depends on a functional auditory nerve, this paper aims to study the hearing outcomes of cochlear implantation in irradiated ears. METHODS: A retrospective study of cochlear implant recipients from our institution who had previously received radiotherapy for head and neck cancers was performed. A control group with cochlear implants who did not receive radiotherapy was recruited. A review of case records, speech discrimination scores (SDS), and a validated subjective questionnaire in the form of the Abbreviated Profile of Hearing Aid Benefit (APHAB) was administered to the study group who fulfilled the inclusion criteria. Global and category scores in both groups were averaged and statistically compared via non-inferiority (NI) testing. RESULTS: With the control group (n=8) as the reference, the -DeltaNI was defined, and a one-tailed lower 95% confidence interval was used for the irradiated group (n=8). The APHAB degree of improvement (%) results were as follows: global, 28.9% (19.32%, -DeltaNI=16.3%); ease of communication, 67.0% (58.36%, -DeltaNI=37.5%); background noise, 53.2% (44.14%, -DeltaNI=26.8%); reverberation, 41.7% (28.85%, -DeltaNI=32.7%); and aversiveness, -46.2% (-67.80%, -DeltaNI=-56.9%). The SDS was 66.9% (56.02%, -DeltaNI=51.0%). From the results, lower 95% confidence interval limits of global APHAB, SDS, ease of communication, and background noise scores of the irradiated group were within the defined -DeltaNI boundary and hence are not inferior to the control. The categories of reverberation and aversiveness could not be proven, however. CONCLUSION: This study demonstrated marked improvements in hearing measured both objectively and subjectively. The overall hearing outcomes after cochlear implantation for post-irradiated patients were not worse than patients who have had no prior irradiation to ear structures.
Auditory Pathways ; Cochlear Implantation ; Cochlear Implants ; Cochlear Nerve ; Deafness ; Ear ; Head ; Hearing ; Hearing Aids ; Hearing Loss ; Hearing Loss, Sensorineural ; Humans ; Nasopharyngeal Neoplasms ; Neck ; Noise ; Retrospective Studies ; Speech Perception ; Surveys and Questionnaires

INTRODUCTIONUniversal newborn hearing screening facilitates early detection of congenital hearing loss. A child found to have severe to profound hearing loss may require a cochlear implant to access sounds in the speech frequency range.

MATERIALS AND METHODSThis retrospective study compared the speech perception outcomes of children implanted at 2 years and below (C1) with those implanted later (C3). Baseline and post-implant speech perception scores were recorded using IT-MAIS, TACL-R or PPVT. The percentage of improvement was calculated for each group and statistical significance was determined using the Student's t-test.

RESULTSThe median follow-up period for C1 (n = 29) and C3 (n = 29) was 29 months (range, 6 to 29 months) and 20 months (range, 5 to 32 months) respectively, which was not statistically significant. Although both groups recorded post-implant improvement of speech reception scores, the difference in the degrees of improvement was statistically significant (P = 0.034).

CONCLUSIONMore rapid development of speech perceptive skills was achieved in children who were implanted early. Early implantation therefore, enables children to develop good core listening skills and to potentially develop spoken language at a young age. This enhances successful integration into mainstream pre-schools which provide the environment for the early nurturing of social and cognitive skills.

Adolescent ; Age Factors ; Child ; Child, Preschool ; Cochlear Implantation ; Female ; Follow-Up Studies ; Humans ; Infant ; Male ; Retrospective Studies ; Treatment Outcome

Female ; Hearing Loss, Noise-Induced ; diagnosis ; Humans ; Leisure Activities ; Male ; Music ; Noise ; adverse effects

INTRODUCTIONSensori-neural hearing loss (SNHL) is a frequent complication of conventional radiotherapy for head and neck tumours, especially nasopharyngeal carcinoma. To manage radiation-induced ototoxicity appropriately, an understanding of the cellular and molecular basis of this complication is necessary.

MATERIALS AND METHODSA medline search of relevant literature was done, focusing on the radiation-induced cellular and molecular processes that lead to hair cell death in the cochlea.

RESULTSRadiation-induced SNHL occurs in the cochlea, with the retro-cochlear pathways remaining functionally intact. By simulating radiotherapy regimes used clinically, radiation-induced cochlear cell degeneration in the absence of damage to the supporting structures and blood vessels has been demonstrated in animals. This could be due to apoptotic cochlear cell death, which has been shown to be associated with p53 upregulation and intra-cellular reactive oxygen species (ROS) generation. Oxidative stress may initiate the upstream processes that lead to apoptosis and other cell death mechanisms.

CONCLUSIONSA model of radiation-induced SNHL based on a dose and ROS-dependent cochlear cell apoptosis, is proposed. This model supports the feasibility of cochlear implantation, should one be clinically indicated. It can explain clinical observations such as radiation-induced SNHL being dose-dependent and affects the high frequencies more than the lower frequencies. It also opens up the possibility of preventive strategies targeted at different stages of the apoptotic process. Antioxidants look promising as effective agents to prevent radiation-induced ototoxicity; they target upstream processes leading to different cell death mechanisms that may co-exist in the population of damaged cells.

Animals ; Cell Death ; Cell Line ; Cochlea ; radiation effects ; Genes, p53 ; Hair Cells, Auditory ; radiation effects ; Hearing Loss, Sensorineural ; etiology ; genetics ; physiopathology ; Humans ; Mice ; Radiation Injuries ; complications ; Reactive Oxygen Species ; metabolism

INTRODUCTIONNoise-induced hearing loss (NIHL) is a preventable condition, and much has been done to protect workers from it. However, thus far, little attention has been given to leisure NIHL. The purpose of this study is to determine the possible music listening preferences and habits among young people in Singapore that may put them at risk of developing leisure NIHL.

METHODSIn our study, the proportion of participants exposed to > 85 dBA for eight hours a day (time-weighted average) was calculated by taking into account the daily number of hours spent listening to music and by determining the average sound pressure level at which music was listened to.

RESULTSA total of 1,928 students were recruited from Temasek Polytechnic, Singapore. Of which, 16.4% of participants listened to portable music players with a time-weighted average of > 85 dBA for 8 hours. On average, we found that male students were more likely to listen to music at louder volumes than female students (p < 0.001). We also found that the Malay students in our study listened to louder music than the Chinese students (p < 0.001).

CONCLUSIONWe found that up to one in six young persons in Singapore is at risk of developing leisure NIHL from music delivered via earphones. As additional risks due to exposure to leisure noise from other sources was not taken into account, the extent of the problem of leisure NIHL may be even greater. There is a compelling need for an effective leisure noise prevention program among young people in Singapore.

Adolescent ; Audiometry ; Female ; Habits ; Hearing Loss, Noise-Induced ; diagnosis ; Humans ; Leisure Activities ; MP3-Player ; Male ; Music ; Noise ; adverse effects ; Risk ; Singapore ; Students ; Young Adult