Hearing impairments caused by genetic and environmental factors

Impairments of hearing and balance are major problems in the field of occupational and environmental health. Such impairments have previously been reported to be caused by genetic and environmental factors. However, their mechanisms have not been fully clarified. On the other hand, the inner ear contains spiral ganglion neurons (SGNs) in the organ of Corti, which serve as the primary carriers of auditory information from sensory cells to the auditory cortex in the cerebrum. Inner ears also contain a vestibule in the vicinity of the organ of Corti—one of the organs responsible for balance. Thus, inner ears could be a good target to clarify the pathogeneses of sensorineural hearing losses and impaired balance. In our previous studies with c-Ret knock-in mice and Endothelin receptor B (Ednrb) knock-out mice, it was found that syndromic hearing losses involved postnatal neurodegeneration of SGNs caused by impairments of c-Ret and Ednrb, which play important roles in neuronal development and maintenance of the enteric nervous system. The organ of Corti and the vestibule in inner ears also suffer from degeneration caused by environmental stresses including noise and heavy metals, resulting in impairments of hearing and balance. In this review, we introduce impairments of hearing and balance caused by genetic and environmental factors and focus on impairments of SGNs and the vestibule in inner ears as the pathogeneses caused by these factors.     

Investigation of environmental and host-related risk factors for tuberculosis in Africa. I. Methodological aspects of a combined design

Host-related and environmental factors for tuberculosis have usually been investigated separately using different study designs. Joint investigation of the genetic, immunologic, and environmental factors at play in susceptibility to tuberculosis represents an innovative goal for obtaining a better understanding of the pathogenesis of the disease. In this paper, the authors describe methods being used to investigate these points in a West African study combining several designs. Patients with newly diagnosed smear-positive cases of tuberculosis are recruited. The effect of host-related factors is assessed by comparing each case with a healthy control from the case's household. The role of environmental factors is estimated by comparing cases with randomly selected community controls. The frequencies of candidate gene variants are compared between cases and community controls, and results are validated through family-based association studies. Members of the households of cases and community controls are being followed prospectively to determine the incidence of "secondary" tuberculosis and to evaluate the influence of geographic and genetic proximity to the index case. This type of design raises important methodological issues that may be useful to consider in studies investigating the natural history of infectious diseases and in attempts to disentangle the effects of environmental and genetic factors in response to infection.     

Behavioral change in longitudinal studies: adoption of condom use by homosexual/bisexual men.

We compared reporting serial cross-sectional prevalence of sexual behavior over time, to reporting individual patterns of behavioral change in a cohort of homosexual men at a six-month interval. Aggregate prevalence rates underestimated the magnitude of change to safer practices, and failed to provide information on relapse to less safe practices. We conclude that it is important to report data based on individual fluctuations in behavior for the evaluation of change over time.     

Silicosis in slate pencil workers: I. An environmental and medical study

An environmental and medical survey was undertaken in the slate-pencil industry in the central part of India. The industrial hygiene survey revealed that concentrations of free silica dust were very high. The medical survey, involving 593 workers, revealed that the prevalence of silicosis in this industry was 54.6%. Of these, 17.7% of workers had conglomerate silicosis (progressive massive fibrosis, PMF). The radiologic appearance of simple and conglomerate silicosis resembled closely the simple pneumoconiosis and progressive massive fibrosis (PMF) among other occupational groups exposed to free silica and also found in coal workers. The pulmonary lesions were detectable after a relatively short duration of exposure. The short latent period of development and the high prevalence of silicosis observed among these workers are related to exposure to high concentrations of siliceous dust in the work environment.     

温州市儿童白血病的环境危险因素研究

【目的】研究儿童白血病的环境危险因素,为临床有效干预提供参考依据。【方法】自行设计白血病危险因素调查表,对2004年7月—2008年12月期间在温州医学院附属育英儿童医院住院及登记的141例0～14岁白血病患儿进行l∶l配对病例对照研究,对所得资料进行单因素分析,选择其中有意义的进行多因素条件Logistic回归分析。【结果】84项指标单因素分析中有15项有统计学意义;其中患白血病前频繁感染、经常吃腌制食品、父亲经常接触有机溶剂、母亲孕期感染、母亲孕期经常接触石油产品、住房周围空气污染、住宅装修入住后有气味、居住地附近有变电所、居住地附近有信号发射塔9项指标在多因素条件Logistic逐步回归分析中有统计学意义。【结论】环境中的物理、化学、生物因素与儿童白血病关联。     

Latex allergy: epidemiological study of 1351 hospital workers.

OBJECTIVE: To determine the prevalence of latex sensitisation among a large group of healthcare workers, study the occupational and non-occupational factors associated with latex allergy, and characterise latex exposure in air and by gloves. METHODS: All 2062 employees of a general hospital in Hamilton, Ontario, Canada who regularly used latex gloves were invited to participate in a cross sectional survey, representing the baseline phase of a prospective cohort morbidity study. Attempts were made to recruit employees who were diagnosed with latex allergy before the survey. Glove extracts were assayed for antigenic protein, and area and personal air samples were obtained on two occasions (summer and winter) to estimate exposure to airborne latex protein. A questionnaire on medical and occupational information was administered by an interviewer. Skin prick tests were performed with latex reagents, three common inhalants, and six foods. RESULTS: The mean (SD) latex protein concentrations were 324 (227) micrograms/g in powdered surgical gloves and 198 (104) micrograms/g in powdered examination gloves. Personal latex aeroallergen concentrations ranged from 5 to 616 ng/m3. There was a total of 1351 (66%) participants. The prevalence of positive latex skin tests was 12.1% (95% confidence interval (95% CI) 10.3% to 13.9%). This prevalence did not vary by sex, age, hospital, or smoking status but subjects who were latex positive were significantly more likely to be atopic (P < 0.01). Participants who were latex positive were also significantly more likely to have positive skin tests to one or more foods (Mantel-Haenszel odds ratio (OR) adjusted for atopy 12.1, 95% CI 7.6 to 19.6, P < 10(-9)). Work related symptoms were more often reported among latex positive people, and included hives (OR 6.3, 95% CI 3.2 to 12.5), eye symptoms (OR 1.9, 95% CI 1.2 to 2.8), and wheezy or whistling chest (OR 4.7, 95% CI 2.8 to 7.9). The prevalence of latex sensitivity was highest among laboratory workers (16.9%), and nurses and physicians (13.3%). When the glove consumption per healthcare worker for each department was grouped into tertiles, the prevalence of latex skin test positivity was greater in the higher tertiles of glove use for sterile (surgical) gloves (P < 0.005) but not for examination gloves. CONCLUSIONS: In this large, cross sectional study of healthcare workers, the prevalence of latex sensitisation was 12.1% (9.5% among all those eligible), and there were significant associations with atopy, positive skin tests to certain foods, work related symptoms, and departmental use of gloves per healthcare worker. This cohort is being followed up prospectively and will be retested to determine the incidence of development of latex sensitivity.     

Background of angina pectoris: social and environmental factors in relation to smoking.

Questionnaire data on about 1200 male twin pairs from the Registry at the Karolinska Institute, Stockholm, and on about 4000 male twin pairs from the Registry of the National Research Council, Washington, DC, have been used to study factors affecting angina pectoris. An operational definition of "angina pectoris" was developed from the questionnaire. In the available data, alcohol drinking, lack of exercise, frequent change of employer, low occupational adjustment and smoking are moderately but significantly related to angina among individuals (disregarding twin relationships) in both Sweden and the US. In monozygous US twin pairs discordant for the above variables, significantly different rates of angina appear only with alcohol drinking. In discordant dizygous US twin pairs, significantly different rates of angina appear with alcohol drinking and with low occupational adjustment. Of the independent variables only smoking and drinking are appreciably associated with each other. These findings suggest that alcohol drinking and to a lesser extent occupational adjustment are related to angina directly and not through their association with other factors such as age, genetic background, smoking, physical exercise and early environment.