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Biomedical subjects

D Koh

Publications and source records attributed to D Koh.

At least 19 recordsLinked to original sources
PubMed1992

Fiberglass dermatitis from printed circuit boards.

Seven cases of fiberglass dermatitis among production operators in the electronics industry are reported. This was due to the repeated daily handling of printed circuit boards (PRCBs). The predominant complaint of the workers was itch of the lateral aspects of the fingers and finger webs. In six workers, unroofed vesicles, pinhead areas of postinflammatory hyperpigmentation, and excoriation marks were noted at these sites. Skin stripping of the affected sites confirmed the presence of fiberglass spicules in all cases. The glass fibers had diameters of 11-16 microns. Patch testing of six of the workers with the European Standard series of allergens revealed no relevant work-related contact sensitizers. Microscopic examination of the free edges and scrapings from the PRCBs showed glass fibers of similar fiber length and diameter to those found in the workers' skin. Fiberglass can be used as a reinforcement filling material in some types of PRCBs. Free edges of such PRCBs have easily detached fiberglass spicules. Workers in frequent contact with these PRCBs can have a fiberglass-induced irritant dermatitis. Preventive measures could include the use of PRCBs with less free fiberglass at its edges, vacuuming of the newly cut boards, use of dusting powder, protective devices and emollients, and improved personal hygiene of the workers.

Adult↗
PubMed1992

Descriptive profile of birth defects among livebirths in Singapore.

A case-control study of birth defects was carried out in Kandang Kerbau Hospital in Singapore for a three-year period from January 1986 until December 1988. This paper presents the descriptive profile of birth defects among livebirths seen in that hospital. Out of 44,842 livebirths, 678 babies were found to have birth defects, giving a prevalence of 15.13 per 1000 livebirths (95% CI 14.0-16.2). The musculoskeletal system was the most frequently affected system accounting for 161 cases with a prevalence of 3.59 per 1,000 livebirths (95% CI 3.06-4.19), followed by 111 cases with defects of the gastrointestinal system (2.47 per 1,000 livebirths 95% CI 2.04-2.98), 88 cases of chromosomal disorders (prevalence of 1.96 per 1,000 livebirths 95% CI 1.57-2.42), 78 cases with defects of the cardiovascular system (1.74 per 1,000 livebirths 95% CI 1.38-2.17), 73 cases with defects of the urogenital system (1.63 per 1,000 livebirths 95% CI 1.28-2.05), and 52 cases with defects of the central nervous system (1.16 per 1,000 livebirths 95% CI 0.87-1.52). The prevalence of cleft lip, cleft palate in isolation, and cleft lip and palate combined was 1.72 per 1,000 livebirths and the occurrence of Down's syndrome was 1 in 700 livebirths. When reviewed 6 weeks postpartum, the rate of false positives at birth was 4%. In a control group of 709 "normal" cases at birth, the rate of cases not detected at birth but detected at 6 week follow-up, false negatives was 0.84%.

Case-Control Studies↗
PubMed1992

Allergic contact dermatitis from resin hardeners during the manufacture of thermosetting coating paints.

5 production operators from 2 factories manufacturing thermosetting coating paint developed work-related skin disorders within 12 months of the introduction of a new powdered paint product. All 5 workers were found to have allergic contact dermatitis from 2 epoxy resin hardeners, both of which were commercial preparations of triglycidyl isocyanurate (TGIC). 2 of the workers had concomitant sensitization to epoxy resin in the standard series and several of the epoxy resin preparations at the workplace. TGIC has been reported as a contact sensitizer both in persons producing the chemical and among end-users of TGIC-containing products. These 5 reported cases document allergic contact dermatitis from commercial TGIC among exposed workers during an intermediate process of powdered paint manufacture. The possibility of substituting this epoxy resin hardener with less sensitizing alternatives should be explored.

Adult↗
PubMed1992

Microwave coagulation therapy on VX-2 carcinoma implanted in rabbit urinary bladders.

In order to evaluate the effectiveness of microwave coagulation therapy on urinary bladder carcinoma, we conducted a series of experiments using carcinoma VX-2 cells designed for the application on animal hosts. Three days after implantation of VX-2 cells into the bladder of the rabbits, microwave coagulation therapy was performed. The antitumor effect, i.e. the survival rate, the histological study and the immunological response of the microwave therapy was examined in comparison with the control group (no treatment), the partially cystectomized group and the sham-operated group (no tumor cell implantation). The results were obtained as follows. (1) The survival rate in the microwave group was greater than that in the control group. (2) The stimulation index value (SI), which represents humoral immunity, decreased postoperatively in all groups. In the microwave group, SI increased gradually beginning 21 days after the transient decrease. (3) Histological findings revealed severe degeneration, necrosis and complete eradication of the cancer cells of the bladder wall in the microwave group, however, perforation of the urinary bladder could not be detected. The results indicate that microwave coagulation therapy is an effective procedure for urinary bladder tumors. Furthermore, microwave therapy may also accelerate the inactivation of immunological suppressors in the carcinoma host, an additional benefit of the microwave procedure.

Animals↗
PubMed1992

Health promotion--a further field to conquer.

We examine some of the interpretations of health promotion. A brief review of the effectiveness of some health promotion programmes in the community and at the worksite in the United States is also presented in view of the similarity of its disease pattern with Singapore. We recommend the following strategies for the practice of health promotion in Singapore: formulation of clearly defined goals; intersectoral collaboration and community participation. Tanahill's model based on the overlapping spheres of health education, disease prevention and health protection is useful in identifying key groups and their roles in health promotion. Green's PROCEED-PRECEDE planning framework which identifies the various behavioural and environmental factors affecting health can help in deriving a highly focused subset of factors as targets for intervention. Research in health promotion should focus on compliance studies on healthy lifestyle regimens, and qualitative and quantitative evaluative studies on process and outcomes of different interventions.

Health Education↗
PubMed1992

Primary tumors of the liver.

Primary tumors of the liver that are of clinical significance are rare. Ninety-five percent of such lesions when encountered will be malignant and only 5% will be benign. Malignant primary hepatic lesions represent 2% to 3% of primary cancers encountered in the United States. Hepatocellular carcinoma constitutes 90% of malignant liver primaries in the adult. Seventy-five percent of cases are associated with cirrhosis of the liver and patients with hepatitis B infection have a 33- to 200-fold excess risk for this malignancy. Cholangiocarcinoma represents 5% to 10% of hepatic primary malignancies while hepatoblastoma is distinctly uncommon in adults. Treatment is primarily surgical, and resectability is limited by the presence of cirrhosis and spread of the tumor within and outside of the liver. Of the benign liver tumors, the liver cell adenoma seem to be associated with oral contraception and have a proclivity for intraperitoneal hemorrhage, especially during pregnancy. Focal nodular hyperplasia is a tumor-like condition that also may be associated with oral contraception. This article describes five cases, two of which had quite unique presentations.

Adult↗
PubMed1991

Biological monitoring for occupational exposure to toluene.

A study was undertaken to examine the relationship between exposure of workers to toluene in the work environment and biological indicators of toluene exposure. The biological indicators studied were toluene in expired air, toluene in blood obtained by the finger prick method, and urinary hippuric acid. The study was undertaken in a factory in Singapore that manufactures speakers for audio systems. A total of 86 female workers exposed to toluene at the workplace and a control group of workers not exposed to toluene were examined. All of them were teetotalers, were nonsmokers, and gave no history of chronic drug usage. The 8-hr time-weighted average exposure level of toluene ranged from 1.6 ppm to 263 ppm. The study showed the expected toluene levels in finger prick blood was 1.4 micrograms/mL after an 8-hr exposure to 100 ppm of toluene. Toluene concentration in expired air of 16 ppm after an 8-hr exposure to 100 ppm compared favorably with other studies. The toluene in blood/expired air ratio was observed to be lower than in other studies. In this study, the expected urinary hippuric acid level for a 100-ppm exposure to toluene was 2.7 g/g creatinine. This level is higher than that recorded in other studies. The results showed that at low levels of toluene, urinary hippuric acid is not a valuable indicator of exposure. Toluene in expired air is the most reliable biological indicator of exposure to toluene.

Air Pollutants, Occupational↗
PubMed1991

[Transurethral intracavitary irradiation for carcinoma of the prostate].

This paper describes a new technique and preliminary clinical results of remote after-loading transurethral irradiation for cancer of the prostate. As of January 1986, twelve patients with adenocarcinoma of the prostate have been treated by our radiotherapy technique. Clinically, 3 patients were in stage B2, 3 in stage C, 3 in stage D1 and 3 in stage D2. These patients have been followed up for 13 to 33 months with a median follow-up period of 20.6 months. The dose of transurethral irradiation was 9-10 Gy. to the prostatic capsule and about 2 Gy. to the rectum in one procedure. We repeated this radiotherapy 3 to 4 times within an about 1-month period. Three patients in stage D1 and one patient in stage C received an additional external beam radiation (40 Gy.) to the entire pelvis. A needle biopsy was also performed every 4-6 months after irradiation. Local tumor response proved rapid and satisfactory as verified by a rectal examination and ultrasonography. The biopsies revealed a 70% negative rate within one year. The most common side effect was transient frequency observed in 7 patients. Severe complications such as incontinence, urethral stricture, or proctitis were not evident. This study suggests that intracavitary irradiation of cancer of the prostate is effective and safe. This method may have wider application.

Adenocarcinoma↗
PubMed1990

Dermatological hazards in the electronics industry.

The advent of the electronics age has resulted in the rapid growth and increasing importance of the electronics industry on a global scale. The main industrial processes are fabrication of semiconductor wafers, printed circuit boards, the assembly of semiconductor devices, printed circuit boards and the final electronic products. The process carry the risk of various work hazards, among them dermatological hazards. These include exposure to irritants and allergens during common operations such as soldering, cleaning operations, materials handling, procedures for control of static electricity and low humidity in the work environment. Even the use of protective clothing may be associated with the risk of dermatitis. In spite of the numerous dermatological hazards, the risk for work-related skin disorders among electronics workers appears to be low when compared to other industries. However, the vast size of the electronics workforce will contribute to large numbers of workers with occupational dermatoses. Occupational health personnel responsible for factories in the electronics industry should therefore be aware of the cutaneous hazards present, and how these may lead to work-related dermatoses.

Dermatitis, Occupational↗
PubMed1990

Chronic neurobehavioural effects of toluene.

Neurobehavioural tests were undertaken by 30 female workers exposed to toluene and matched controls with low occupational exposure to toluene. The environmental air levels (TWA) of toluene was 88 ppm for the exposed workers and 13 ppm for the controls. The toluene in blood concentrations for the exposed workers was 1.25 mg/l and for the controls 0.16 mg/l. Statistically significant differences between workers exposed to toluene and controls in neurobehavioural tests measuring manual dexterity (grooved peg board), visual scanning (trail making, visual reproduction, Benton visual retention, and digit symbol), and verbal memory (digit span) were observed. Further, the performance at each of these tests was related to time weighted average exposure concentrations of air toluene. The workers exposed to toluene had no clinical symptoms or signs. The question arises as to whether these impairments in neurobehavioural tests are reversible or whether they could be a forerunner of more severe damage.

Adult↗
PubMed1990

Dermatological symptoms among visual display unit operators using plasma display and cathode ray tube screens.

A questionnaire survey was conducted to determine the prevalence of dermatological complaints in 672 full time visual display unit (VDU) operators in Singapore. Two hundred and sixty-nine operators worked with plasma display (PD) screens, while the other 403 used cathode ray tube (CRT) monitors. The overall one year period prevalence rate for dermatological complaints was 12%. Thirty-six (13%) PD operators and 46 (11%) CRT operators had skin complaints. The age and sex distribution of persons in the two groups were similar. Twenty-eight (10.4%) PD workers and 24 (6.0%) CRT workers had symptoms of itch, tingling, or the feeling of being stroked by a feather after working with the VDU for some time. Furthermore, 19 (7.1%) PD and 14 (3.5%) CRT workers stated that their skin problems improved during weekends or when they were off duty. The difference between these rates were not statistically significant. Operators with dermatological complaints in the past year were more likely to have a personal history of atopy, complain about their work environment, and have musculoskeletal symptoms of the shoulder and low back. The results indicate that the prevalence and nature of dermatological symptoms among operators using either type of VDU monitor are similar.

Adult↗
PubMed1989

Neurochemical effect of lead exposure: a study on catecholamine metabolism.

In an attempt to examine the neurochemical changes of lead exposure, a study was conducted on 106 lead workers and a control group of 25 nonexposed workers. The urinary excretion of major catecholamine metabolites, homovanillic acid (HVA), and vanillylmandellic acid (VMA) were measured. Workers exposed to lead had a mean blood lead concentration of 43.2 micrograms/100 ml, whereas the concentration for workers not exposed to lead was 12.7 micrograms/100 ml. Urinary HVA was significantly elevated in the exposed group when compared with controls (p less than 0.01). HVA was also found to be associated with an increase of lead in blood. Although not statistically significant, the VMA excretion was also noted to be moderately elevated; however, it is recognized that the present study was unable to establish a highly significant dose-response relationship between lead exposure and HVA excretion, as has been reported earlier in lead-poisoned children.

Adult↗
PubMed1989

Statistical evaluation of agreement between two methods for measuring a quantitative variable.

Methodologic research is often concerned with determining whether two methods (procedures, laboratory instruments) can be used interchangeably for measuring some quantitative variable of interest. Logically, one method can be used as a surrogate of another provided the methods show high agreement on the measured results. Although the product-moment correlation (r) is often used as an indicator of agreement, this index is in fact inappropriate for this purpose. The intraclass correlation (r1) is the correct statistic for assessing agreement or consistency between two methods. Another criterion sometimes used for supporting interchangeability is the similarity of the mean measured results obtained by the two methods. However, similarity of means (aggregate agreement) does not necessarily indicate individual-subject agreement, and it is the latter that is the pre-requisite for interchangeability. On the other hand, a marked difference between two means (lack of aggregate agreement) does necessarily indicate lack of individual-subject agreement and therefore non-interchangeability. Herein we suggest that two methods for measuring a quantitative variable can be judged interchangeable provided all of the following conditions are met: first the methods must not exhibit marked additive or nonadditive systematic bias; second the difference between the two mean readings is not "statistically significant"; third, the lower limit of the 95% confidence interval of the intraclass correlation is at least 0.75. Statistical procedures to evaluate these conditions of interchangeability are described in detail. A computer program coded in SAS to carry out the procedures is listed in the Appendix. A similar program coded in DBASE III PLUS for the microcomputer is available upon request.

Analysis of Variance↗
PubMed1989

Uses and limitations of microcomputers for epidemiological research in occupational health.

The rapid improvements in microcomputer systems have contributed to ease of performance of epidemiological research in occupational health. Computers now available can aid in all stages of research- from the early stages of literature review to data collection, analysis and presentation. Optical storage devices now allow large occupational health data bases to be stored on a single compact disc, with the information accessible by microcomputer. Hand-held computers and optical scanners allow paperless collection of field data. Epidemiological analysis and data presentation is easily done with software packages, some of which are in the public domain. However, there are limitations in the use of computers for any epidemiological research. Investment of time is required to learn the use of a computer. Care needs to be taken to ensure accurate data entry, and correct choice has to be made of methods for subsequent statistical analysis. Microcomputers are valuable as labour saving devices, but cannot replace proper planning, execution and appropriate data analysis in epidemiological research in occupational health.

Health Services Research↗
PubMed1989

[Transurethral microwave coagulation of bladder cancer in elderly patients].

Since April 1985, 72 patients with bladder cancer have been treated by transurethral microwave coagulation (TUMC). In this procedure, tumors were irradiated with microwave energy of 100 watts for 2-16 minutes. A total of 20 patients were 70 years old or older, including 5 who were more than 80 years old. These 20 patients have been followed for 6 to 32 months with a median follow-up of 14.7 months. After TUMC, tumors completely disappeared endoscopically and histologically in all patients. Four patients had heterotopic recurrences. In all patients, serious complications were not seen during and after TUMC. Our clinical experience revealed that TUMC was the useful therapeutic method for bladder cancer in elderly or poor-risk patients. In this paper, we describe the technique of TUMC and preliminary clinical results.

Aged↗