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Biomedical subjects

D Koh

Publications and source records attributed to D Koh.

At least 73 records · Page 4Linked to original sources
PubMed1995

Risk factors for birth defects in Singapore: a case control study.

To explore possible risk factors for birth defects, a matched case-control study was carried out at Kandang Kerbau Hospital in Singapore from January 1986 to December 1988. Cases and controls were selected from livebirths born in that hospital during that period. Cases were babies who were clinically detected as having defects at birth and the diagnosis reconfirmed at 6 weeks post partum. Each case was matched to a control by maternal age, ethnic background of mother, the same class of maternity ward and time of delivery. Five hundred and seventy-two matched pairs were accrued for the study. The parents of both cases and controls were interviewed at 6 weeks post partum. Information on the medical and birth history of both mother and baby was obtained from medical records. Using conditional logistic regression analysis to adjust for potential confounders, the strongest risk factors for birth defects were family history of birth defects (OR 3.3; 95% CI 1.8-6.4) and parents having a previous abnormal baby (OR 2.4; 95% CI 1.1-5.3). Other notable risk factors included drug history during pregnancy (OR 1.2; 95% CI 0.8-2.0), the ingestion of traditional medicine during pregnancy (OR 1.4; 95% CI 1.0-2.0), injuries or accidents during pregnancy (OR 2.2; 95% CI 1.5-3.2) and maternal diabetes mellitus (OR 1.3, 95% CI 0.3-7.1). Mothers in professional occupations (OR 1.4, 95% CI 0.7-2.6) and those in production occupation (OR 1.2, 95% CI 0.9-1.7) had an increased risk for birth defects compared to housewives.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1994

Symptoms, lung function, and diurnal variation in peak expiratory flow rate among female solderers in the electronics industry.

The purpose was to determine if solderers had increased diurnal variation (DV) in peak expiratory flow rate (PEFR) and chronic impairment of lung function. A cross-sectional study of 150 female operators doing manual soldering using flux-cored (rosin-based) solder wire and 52 administrative staff from two electronics factories was carried out. They answered a questionnaire, had their forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) measured and their 3-hourly PEFR monitored for 5 working days. The DV in PEFR was the difference in the daily maximum and minimum PEFR expressed as a percentage of the maximum. Six solderers with smoking history were excluded from the analysis. Solderers had a significantly higher prevalence of work-related eye (14.6%) and nose (10.4%) irritation. The prevalence of cough, breathlessness, and wheezing was low. There was no overt case of occupational asthma. The DV in PEFR of 6.0% was not increased. The analysis of FEV1 and FVC was restricted to Chinese only (101 solderers and 51 controls): these were not significantly different. Solderers with 5 or more years of exposure had a significantly lower FEV1/FVC (%) of 88.4% after adjustment for age. In conclusion, solderers with 5 or more years of exposure may have a mild obstructive effect apart from smoking, asthma, or age.

Adult↗
PubMed1994

Colophony--uses, health effects, airborne measurement and analysis.

Colophony (rosin) is a widespread natural product obtained form species of the pine family Pinaceae. One of the most important uses of unmodified rosin is in electronic solder fluxes while the main areas of use of chemically modified rosin are paper sizing, adhesives, paints, varnishes, printing inks and plasticisers. Colophony is well recognized as a skin sensitizer and is also the third highest cause of occupational asthma. However, the specific allergens involved particularly in occupational asthma have not been comprehensively assessed or identified. This paper reviews method of colophony production, its uses and health effects and discusses the important issue of its chemical analysis and the choice of a suitable marker for monitoring colphony fume.

Air Pollutants, Occupational↗
PubMed1994

Skin disorders among hand solderers in the electronics industry.

Full-time solderers (n = 150) and non-soldering administrative staff (n = 52) were interviewed and examined to determine the prevalence of work-related rashes, to assess their acne status and to measure their forehead skin sebum levels with a Sebumeter. The period prevalence rates (of ever having a work-related skin rash since working as a solderer) for the 82 solderers using multicored solder wire and for the 68 workers using liquid flux were 19.5 per cent and 10.3 per cent respectively. Among the liquid flux solderers, 29 used cotton gloves. The prevalence rate of work-related skin rashes was 3.4 per cent in this group, compared to 15.4 per cent among the 39 ungloved workers. A similar finding was noted among the multicored solder wire users (9 per cent of the 11 gloved workers and 21 per cent of the 71 ungloved workers). On examination, six solderers (all ungloved multicored flux users) had work-related dermatitis of the hands or fore-arms. The point prevalence rate of work-related dermatitis among all solderers was 4 per cent. For non-occupational dermatitis, the point prevalence rate was 2.7 per cent among the solderers and 4 per cent among the administrative staff. The point prevalence and severity of acne among the 150 solderers were the same as those of the 52 administrative workers who were of a similar age and sex distribution. Forehead skin sebum levels, after adjusting for possible confounding factors such as age, atopic status and time elapsed since the last face wash, were also similar in the two groups of employees.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Paint--health and environmental risk management.

Over the past ten years, concern over the possible health effects of occupational exposure to solvent based paints, as well as more general concerns over the environmental impact of such products, has led to several international workshops. The most recent symposium, convened in Singapore in June 1992, brought together a group of international experts from academic, government and industrial backgrounds. The purpose was twofold: to identify consensus areas related to health and environmental risk assessment of paints, and to describe where further work was necessary to enhance convergence of view. The symposium proved particularly valuable in focusing on issues of current relevance and providing useful guidance for risk management strategies within the industry. The main areas addressed were the general principles and specific processes in risk assessment, organic solvents in the risk assessment process, risk communication, and comparative risks of water-based and solvent-based paints. Each subject area was introduced by a keynote speaker, followed by syndicate discussions and conclusions. To our knowledge this was the first workshop of its kind and we believe it provided a valuable model for the future.

Communication↗
PubMed1994

Occupational health through primary health care clinics in Singapore.

The training of primary health care workers in occupational health is important for the provision of occupational health care to the workforce. In Singapore, over 400 Designated Factory Doctors, mostly general practitioners, have been trained. Occupational health is also incorporated in the training of family medicine trainees. Referral centres for cases of suspected work-related diseases are also available. Two specialist occupational health clinics function within Government polyclinics serving the large working population in Singapore. One such clinic operates every Wednesday morning at the Jurong Polyclinic. In the last four years, 485 patients with work-related complaints were seen. There were 268 cases (55%) of occupational skin disease, 74 patients (15%) with respiratory complaints, 38 patients (8%) with acute toxic exposures and 36 patients (7%) with musculoskeletal complaints. Three hundred and forty-nine of the referrals (72%) came from the Jurong Polyclinic doctors, with small numbers from other polyclinics and neighbouring private practitioners. The experience gained in conducting this clinic demonstrated that significant numbers of diseases seen at the polyclinic are work-related in varying degrees. Hence, there is a need for the further development of occupational health care delivery within the primary health care system. This can be achieved by improving occupational health training for all primary health care workers, providing an occupational health resource person at primary health care centres, and raising the awareness of such referral facilities in occupational medicine.

Humans↗
PubMed1994

Health care costs in industry.

The costs of providing health care in industries must remain affordable and rational. While recognising that employers have a moral commitment to workers' health and welfare, it must also be realised that resources committed to this end are finite. Furthermore, if these resources are spent on the minority, then all the more, the interests of the majority must be defended, as ultimately, medical expenses must form part of the wage costs. Both demand and supply factors of health care must be tempered. The factors influencing demand include the abuse and inappropriate use of health services, unhealthy lifestyle factors, the ageing of the population and the threat of litigation, while the factors affecting supply include new technology, easy accessibility and the creation of demand by doctors. Cost containment strategies should include the collection and interpretation of data on health care costs, the rationing of services, and cost sharing. Cost sharing is one of the most persuasive means through which a sense of cost sensitivity on the part of the consumer can be achieved. This can, and should, be incorporated in whatever form of purchase plan that employers wish to implement.

Cost Control↗
PubMed1994

The safe use of visual display units.

The use of visual display units (VDUs) has been increasing throughout the world in the last decade. The most common type of VDU uses the cathode ray tube, and this has resulted in concern among the public about possible adverse effects of radiation exposure from VDU use. Radiation emission from the VDU is negligible and has not been shown to be harmful to health, or to cause adverse pregnancy outcomes. However, many full-time VDU users often complain of visual discomfort, musculoskeletal discomfort of the neck, lower back and upper limbs, and psychosocial problems. The likelihood of having such complaints is positively associated with the duration of hours worked per day, the nature of the work, work schedules and workload, and workstation design and layout, rather than the VDU technology per se. Such complaints are often transient and resolve rapidly when stopping work. Other alleged adverse health effects of VDU use, such as skin complaints, have been discounted. Guidelines on the safe use of VDUs have been issued by various industrial corporations and national institutions. The guidelines generally address three main areas, viz (1) the provision of a suitable workstation and work environment, (2) good work technique and work schedules, and (3) preplacement and periodic health examinations for the detection and correction of personal impairments. The implementation of these guidelines will resolve many of the potentially correctable factors which result in many of the adverse health effects associated with VDU use.

Computer Terminals↗
PubMed1994

A prevalence study of chronic rhinitis among residents in Telok Blangah Town, Singapore.

A community-based questionnaire survey on a random sample of 562 persons aged seven to 81 years residing in the flatted housing estate of Telok Blangah, Singapore, was studied to determine the prevalence of chronic rhinitis, its associated risk factors and severity of the symptomatology. Chronic rhinitis was defined as the presence of nasal obstruction or clear, watery discharge together with any or both of the following: tearing eyes or sneezing, for a period of more than one month. The overall prevalence was 32.5% with Chinese having the highest ethnic specific rate of 33.9% followed by Indians (27.1%) and Malays (25.4%). The age-specific prevalence rates showed a clear downward trend with increasing age (P < 0.0001). Among the risk factors studied, family history of atopy ranked the highest followed by personal history of atopy and age group (< 30 years and 30 years or more). Most of the chronic rhinitis' symptoms (79%) were graded as not severe.

Adolescent↗
PubMed1994

A study of needle-stick injuries among house officers in a major hospital.

House officers (HO) undergoing housemanship in the departments of Surgery, Medicine and Orthopaedics in a major hospital were studied with regard to the incidence and causes of needle-stick injuries via a self-administered recall questionnaire. A response rate of 79% (44 out of 56 HOs) was obtained, of which 35 HOs had completed 2 months of housemanship and 9 had completed 8 months. A total of 171 needle-stick injuries (1.2 per HO-month) were reported with 6 HOs never sustaining an injury. The more experienced HOs had less injuries than the less experienced HOs with an incidence rate of 4.65 (95% confidence interval of 4.08-8.87). Resheathing was the commonest reported cause of injury (45% of 113 described cases). Forty-three HOs (90%) reported that they frequently resheathed used needles before disposal. Most HOs (61%) felt that they were at nil to moderate risk of contracting an infectious disease from a needle-stick injury. A system of reporting and policies on management of infected personnel may be needed to monitor this health hazard.

Blood-Borne Pathogens↗
PubMed1993

Wittig reaction of unprotected D-aldopentoses with stabilized ylides: metal-ion effects.

Each of the four D-aldopentoses (1-4) reacts in the unprotected form with Ph3PCHCO2Me (5) in THF to give stereoselectively the corresponding trans-alpha,beta-unsaturated C7 Wittig adducts, isolated as the corresponding 4,5,6,7-tetraacetates (7-10) or 4,5:6,7-di-O-isopropylidene derivatives (11-14). Concurrently formed are also bicyclic, 1,4-lactone derivatives, isolated as their 5,7-diacetates (15-18) or 5,7-O-isopropylidene derivatives (19), arising through intramolecular Michael addition from the initial acyclic adducts. Formation of the cyclized products is suppressed by incorporation of Cu(OAc)2 in the reaction mixture, permitting preparative isolation of the hept-3-enonate derivatives 7-10, useful as dienophiles in Diels-Alder carbocyclizations with chirality transfer. Optimized yields were 25% (D-ribo), 50% (D-arabino), 49% (D-xylo), and 61% (D-lyxo). Under Cu(OAc)2-catalyzed conditions, the formation of small proportions of 3,7-anhydroheptonic acid esters (21 and 23) was observed in the D-arabino and D-xylo series, but not with the other two pentoses.

Carbohydrate Conformation↗
PubMed1993

Stereocontrol in Diels-Alder cycloaddition to unsaturated sugars: reactivities of acyclic seven-carbon trans dienophiles derived from aldopentoses.

Acyclic trans-2,3-unsaturated aldoheptonate derivatives (1-9) obtained from D-aldopentoses by Wittig chain-extension served as dienophiles for a detailed comparative study of their asymmetric Diels-Alder cycloaddition with cyclopentadiene. Cycloaddition under uncatalyzed thermal conditions gave mixtures of the four possible stereoisomeric norbornene adducts. The endo:exo ratios and the diastereofacial selectivities in the formation of the adducts were determined by NMR spectroscopy and by chemical transformations. The quantitative distribution of adducts as a function of stereochemistry of the dienophile is discussed.

Carbohydrate Conformation↗
PubMed1993

Stereocontrol in Diels-Alder cycloaddition to unsaturated sugars: reactivities of cis-dienophiles with cyclopentadiene.

Cycloaddition of cyclopentadiene with a D-arabinose-derived cis-dienophile, methyl (Z)-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-arabino-hept-2-enonate (2), under thermal conditions gave essentially a single norbornene adduct, isolated crystalline in 81% yield and identified by NMR spectroscopy and X-ray crystallography as methyl (5R,6S)-6-endo-(1,2,3,4-tetra-O-acetyl-D-arabino-tetritol-1-yl)bic yclo [2.2.1]-hept-2-ene-5-endo-carboxylate (3). The diene adds exclusively from the si-face of the dienophile and give only the endo product. The same sequence starting from L-arabinose gave the enantiomer (7) of 3. In contrast, a related cis-dienophile (9) having a butenolide ring reacts with cyclopentadiene from the opposite (re) face giving mainly the endo adduct (5S,6R)-6-endo-(2,3,4-tri-O-acetyl)-D-arabino-tetritol-1-yl)bicycl o [2.2.1]hept-2-ene-5-endo-carboxylic acid 1,4-lactone (10), isolated crystalline in 70% yield, whose structure was again established by NMR spectroscopy, and firmly consolidated by X-ray crystallography. The minor (11%) product was the exo(5S,6R) isomer 11. A cis-enonate 14, analogous to 2 but deoxygenated at the allylic position, showed negligible diastereofacial selectivity and reacted with cyclopentadiene to give a mixture of all four possible adducts. A 6-membered ring dienophile 16 was also subjected to the same cycloaddition for comparison with the butenolide 9; it gave principally the two endo products 17 and 19 in 31 and 38% yields, respectively, accompanied by 12% of a mixture of the two exo products (18 and 20). The quantitative distribution of cycloaddition products as a function of dienophile stereochemistry is discussed. The high degree of asymmetric induction observed, especially with the readily accessible dienophiles 2 and 7, provides a valuable route of access to enantiomerically pure tetra-C-substituted cycloalkanes.

Carbohydrate Conformation↗
PubMed1993

Factors influencing the assessment and control of occupational hazards in developing countries.

The principles of occupational health may be the same in the developed and developing countries. However, there can be a wide diversity in practice. The exposure to chemicals at the workplace in developing countries is usually of a different nature, and the level of exposure is generally of a higher magnitude. The leading occupational diseases in developing countries are also very different to those reported in industrialized nations. For hazard evaluation in developing countries, more factors need to be considered. Problems are usually more complicated as most workplaces are subjected to many factors which typify small-scale industries. Low capital investment often culminates in cutbacks on necessary expenses, especially on occupational or environmental health activities. Thus the health, safety, and welfare of the workers are usually overlooked. This situation helps only to promote greater risks to the workers. Furthermore, many workers in the developing countries suffer from poor nutrition, endemic diseases, and other debilitating conditions. For these reasons, it is possible that currently recommended occupational exposure limits could allow injury to workers in the developing nations. When carrying out health assessment, careful attention must be paid to cultural practices, genetic components, working conditions, and other predisposing factors. This paper reviews some of the current techniques commonly used for the monitoring of toxic substances and an in-depth discussion on various problems facing the developing countries concerning the usage of these techniques.

Child, Preschool↗
PubMed1993

A study of needle stick injuries among medical undergraduates.

A study was conducted to determine the incidence and causes of needlestick injuries among 158 medical undergraduates who had completed their first clinical year. A response rate of 97.5% (154 out of 158 students) was obtained, of which 54 students (35.1%) reported at least one needlestick injury. The commonest cause of injury was during the process of venepuncture (27%), followed by uncapping of needles (22.2%) and recapping of used needles (19.8%). The highest incidence of injury occurred during a medical posting (33/154 students), followed by surgical posting (14/154 students) and elementary clinics (9/154 students). Formal training on handling of used needles was reported by only 15-23% of the students in the various postings. The awareness of risk of contracting diseases from needlestick injuries was high (84.4%).

Bloodletting↗