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Biomedical subjects

D Koh

Publications and source records attributed to D Koh.

At least 55 records · Page 3Linked to original sources
PubMed1999

Applications of new technology in molecular epidemiology and their relevance to occupational medicine.

Technological advances in molecular biology over the past 2 decades have offered more complex techniques that can be used to study the role of specific exogenous agents and host variables that cause ill health. Increasingly, studies in human populations use this new technology, combined with epidemiological methods, to shed light on the understanding of the biological processes associated with development of disease. This approach has many potential applications in occupational and environmental medicine (OEM), and some aspects of the work in this growing field are reviewed. An understanding of biochemistry and genetics at the molecular level, specific knowledge on metabolism and mechanisms of action, and epidemiology have become increasingly important for the OEM practitioner. This is necessary to consider the major question of validation and relevance of these molecular biomarkers. As end users, OEM practitioners should also consider the impact of these advances on their practices. For example, the availability of genetic tests to identify susceptible workers raises issues of ethics, individual privacy, right to work, and the relevance of such tests. Several studies have presented data on the association of environmental measurements and various biomarkers for internal and biologically effective dose, genetic polymorphisms, and early response markers. Given the limitations of individual molecular biomarkers in assessing risk to health, and the multifactorial nature of environmental disease, it is likely that such an approach will increase our understanding of the complex issue of mechanisms of disease and further refine the process of risk assessment.

Genetic Markers↗
PubMed1998

Occupational health in Singapore.

Singapore, a newly industrializing country in Southeast Asia, has a resident population of 3 million and a work force of 1.75 million. Most workers are employed in the manufacturing, services, and commerce sectors. Agricultural and mining activities are negligible. In 1996 the infant mortality rate was 3.8 per 1,000 live births and the life expectancy at birth was 77 years. In 1996 the total industrial accident rate was 2.7 per million man-hours worked and the severity rate was 353 industrial man-days lost per million man-hours worked. The shipbuilding and construction industries had the most frequent and most severe accidents. In the same year, 1,521 cases of occupational disease were notified to, and confirmed by, the Ministry of Labor. The majority of cases involved noise-induced hearing loss. There is substantial underreporting of cases. New cases that are expected to appear will be work-related illnesses such as musculoskeletal or psychosocial disorders. The principal occupational health legislation in Singapore is the Factories Act. Although it selectively targets workers at highest risk of developing occupational illness, its main limitation is the exclusion of nonfactory workers, who comprise 63% of the working population. Labor regulations are enforced by the Ministry of Labor. Workmen's compensation paid in 1995 amounted to S $46.6 million (U.S. $1=S $1.75). Education and training in occupational health is provided by employer federations, employee unions, and various government agencies. Occupational health is taught to medical students during their undergraduate training. Postgraduate-diploma and Masters programs in occupational medicine are also available. About 600 doctors in Singapore have some form of postgraduate training in occupational health. Health care for workers is offered either through the private sector or through government clinics and hospitals. Although Singapore has made great strides in protecting and promoting the health of its workers, it must constantly strive to strengthen its commitment to occupational health and safety. New problems in the next century must be anticipated and solutions, implemented. Improved training and development of health professionals is needed such that they be better prepared to deliver optimal occupational health care. Finally, labor legislation must be appropriate and responsive to protect the health of all workers.

Accidents, Occupational↗
PubMed1998

Biomarkers, screening and ethics.

Rapid scientific advances, such as those in biomarker technology, have made a significant impact on the ethics and practice of occupational health. Biomarkers are extensively used in occupational health practice. In the pre-employment stage, preventive or predictive testing can be performed. Preventive testing aims to avert accidents that may occur if a medically unfit worker undertakes a job that he is unable to perform. For safety sensitive jobs, routine testing of a worker's functional capacity in the actual job would suffice in most cases. However, a recently quotes application of a test is the screening for mutations of the cardiac myosin-heavy chain and troponin genes among asymptomatic persons with a family history of sudden death from hypertrophic obstructive cardiomyopathy. Predictive testing hopes to forecast the risk of a worker developing an illness. The aims may vary. One aim may be to exclude a susceptible worker from working in a hazardous environment. Another aim may be to avoid employment of a worker who is likely to develop an illness which could lead to higher employer health care costs. A pertinent question to consider is whether the test undertaken is to benefit the individual or to fulfil some administrative or financial need. Among exposed workers, screening may be conducted for biomarkers of exposure or effect. As the aim is to prevent the onset of clinical illness, the physician must take responsibility for initiating requests for screening. The appropriate response to the effect of technical and societal advances on ethics is the updating of ethical guidelines by the profession. However, in the context of unvalidated biomarkers being used for screening, it may be necessary to require a regulatory body to ensure that the tests are accurate and effective, and that they are not used to discriminate against individuals.

Biomarkers↗
PubMed1998

Assess workers' needs and preferences first before planning a physical fitness programme: findings from a polytechnic institute in Singapore.

Workplace physical fitness programmes are usually poorly attended because the activities do not meet workers' needs. We investigated leisure-time physical activity and its relation to sociodemographic characteristics and cardiovascular risk factors in a polytechnic institute in Singapore before planning a physical fitness programme. Low leisure-time physical activity (defined as no activity or engaging in physical activity less than once per week) was more prevalent among older women, married workers, smokers and men with unhealthy dietary habits. The type of physical activity varied with age and gender, with a preference for walking by women and older men and jogging by younger men. Low physical activity was significantly associated with sickness absence and self-reported stress in women and higher values of triglycerides and low density lipoprotein cholesterol in men. This survey helps to identify target groups for physical fitness programmes and determine leisure-time physical activities specific to workers' preferences by age and gender.

Absenteeism↗
PubMed1997

High-performance liquid chromatographic determination of dehydroabietic and abietic acids in traditional Chinese medications.

In Asia, there is still a high usage of traditional Chinese medicament by the general population. Some patients with contact dermatitis to these medicaments have been found to be sensitive to colophony on patch testing. Dehydroabietic acid (DHAA) and abietic acid (AA) are the main components of colophony and believed to be the agents responsible for skin sensitization. This paper describes a reliable high-performance liquid-chromatographic method for determining these two resin acids in ointment samples. The samples were either pretreated with diethyl ether or treated with acetonitrile directly by ultrasonication for 30 min. One volume of this sample was added to an equal volume of water and purified by solid-phase extraction. The mobile phase used was methanol-water-phosphoric acid (87:13:0.02, v/v) and the flow-rate was 1 ml/min. DHAA and AA were detected at 4.3 and 6.3 men with ultraviolet detection at wavelength 200 and 239 nm, respectively. However, fluorimetric detection with an excitation wavelength of 225 nm and emission wavelength of 285 nm, provided more selective determination of DHAA. The detection limits for DHAA and AA were 1 ng. Analytical recovery generally exceeded 90%. We analyzed nine types of commonly used topical Chinese medicaments and two types of Western medical ointments in Singapore. The results showed that most of these medicaments contain colophony below 5 ppm (micrograms g-1). Only one Chinese medicament contained > 70 ppm of both allergens and one of the Western medical ointments contained 0.2% of DHAA and 2.2% of AA.

Abietanes↗
PubMed1997

Allergic contact dermatitis from grasses.

This study attempts to demonstrate the existence of allergic contact dermatitis from grass, and to develop a patch test series to screen patients with grass intolerance. 6 common grass species from lawns and military training areas were collected. Solvent extracts of polar, non-polar and volatile fractions were prepared and used for patch testing in 20 control subjects and 46 patients with a history of grass intolerance. The 20 controls had negative responses to patch testing. 5 out of 46 patients had positive patch tests to Axonopus compressus (carpet grass), Ischaemum muticum (seashore centipede grass), Imperata cylindrica (lalang), Panicum maximum (Guinea grass) and Pennisetum purpureum (elephant grass). Reactions to the non-polar fraction for all 5 species were noted. This study demonstrates the existence of allergic contact dermatitis from various common species of grass. In our series, this is seen in 11% of those with a history of grass intolerance.

Adolescent↗
PubMed1997

Two-year follow-up of a behavioural weight control programme for adolescents in Singapore: predictors of long-term weight loss.

We followed up 112 obese adolescents enrolled in a weight control programme at a polytechnic institute in Singapore for two years. The programme used behavioural and environmental strategies to help students make sustained changes in their diet and physical activity pattern. Of these 112 students, 71.4% lost weight compared to 60% in a comparison group of 86 obese students not in the programme. About one-third (29.5%) had achieved normal weight [body mass index (BMI) < 25] with a mean weight loss of 3.3 kg among boys and 2.3 kg among girls. A stepwise multiple linear regression to determine the best combination of variables predictive of weight loss found three variables to be significantly associated with long-term weight loss: percent of weight loss in the initial 8-week intervention period; increase in exercise or physical activity following intervention, and income. These 3 variables accounted jointly for 59.5% of the variance in weight loss in males and 48% of weight loss in females. We recommend intensive efforts during the initial intervention phase to help students lose weight and strategies that can help students incorporate exercise or increased physical activity in their daily routine.

Adolescent↗
PubMed1996

Spatially heterogeneous discrete waves in predator-prey communities over a patchy environment.

A model motivated by the earlier work of J. D. Murray and D. Stirzaker is proposed to describe the dynamics of predator-prey communities over a patchy environment. The model is a system of delay differential equations. It is shown that if only one time lag is incorporated into the model, then a branch of spatially homogeneous periodic solutions occur as a primary Hopf bifurcation. However, if two time lags are used to measure different delayed factors in the process of growth, decay, and predator consumption of the prey population, then stable spatially heterogeneous periodic solutions (discrete waves or phase-locked oscillations) may exist. The utilized method is based on center manifold, normal form, and equivariant Hopf bifurcation theory.

Animals↗
PubMed1995

Case studies in occupational medicine for medical undergraduate training.

Medical undergraduate tutorials in occupational medicine were introduced in 1993 in Singapore. The tutorials discuss three case studies of patients likely to be encountered in primary health care practice--occupational dermatitis, tinnitus in a noise-exposed worker, and the finding of anaemia in a pre-employment examination. The cases are used to illustrate the importance of identification of occupational factors in the causation of disease; consideration of occupational factors in the management of disease; and measures for prevention of occupational and work-related diseases and promotion of health at work. Staff and student responses to the case studies have been positive. All five staff members involved in the teaching enjoyed the experience, and over 90% of the 105 students who participated in the tutorial felt that the material was well prepared, the time was well spent, and that the tutorials had thrown new light on and overcome difficulties encountered during the course.

Curriculum↗
PubMed1995

An outbreak of occupational dermatosis in an electronics store.

An outbreak of skin disorders was noted by the primary care physician responsible for the health care of 52 employees in an electronics store. The cases occurred after termite treatment of the store, and the breakdown of the air-conditioning system in several areas in the store. Investigations were initiated to allay worker concern that the chemicals used for termite treatment (in particular, arsenic trioxide) were responsible for the outbreak. 9 of the 52 workers were found to have heat rash (miliaria rubra). 21% (7) of workers who worked in non-air-conditioned areas had heat rashes, as compared to 11% (2) of workers who worked in air-conditioned work zones. 2 workers had contact dermatitis due to exposure to greaseless lubricant, and 8 other workers had a non-work-related skin disorder. Indoor wet bulb globe temperature index measurements in the non-air conditioned areas were within threshold limit values, but ventilation in these areas was very poor. 2 environmental samples had non-detectable limits of arsenic.

Air Conditioning↗
PubMed1995

Health and safety ethics for management.

All employers are ethically required to provide a safe and healthy workplace for their employees. Health and safety professionals (HSP) may often be employed either full-time or part-time to achieve this end. The HSP should be viewed as a non-partisan provider of safety and health services at the workplace. He is equally on the side of management and worker in discharging his duties. His primary goal is to achieve a safe and healthy workplace and to improve the health of the workforce. Ethical dilemmas may surface in the course of the HSP's work largely because there may be occasions when there are conflicts of interest and loyalty derived from the different roles of the HSP. The best way to resolve such dilemmas is to prevent them from arising. However, when this is not possible, management's understanding of the professional ethical considerations of the HSP will help to improve the working relationship and professional results of these staff. Several aspects in the HSP's work require management's understanding. These include subjects such as communicating information on staff-medical examinations to management, and the disclosure of commercially confidential information to assess related health risks. Management should also be aware that guidelines have been developed by a number of professional health and safety organizations for their members. In the instances when answers to ethical questions cannot be resolved, these guidelines can be consulted, in conjunction with discussions with senior HSP colleagues.

Commerce↗