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Biomedical subjects

S K Ng

Publications and source records attributed to S K Ng.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cutaneous polyarteritis nodosa: a case report and literature review.

Cutaneous polyarteritis nodosa (CPN) is an uncommon form of vasculitis. It exists as a separate entity, though bearing similar name with polyarteritis nodosa (PAN) which is an aggressive systemic vasculitis with multi-organ involvement. CPN runs a chronic but benign course. Its aetiology is unknown and it usually presents with painful nodules on the legs with mild constitutional symptoms, and extracutaneous features of arthralgias, arthritis, neuropathy and myopathy. No mortality has been reported thus far. It is therefore important to distinguish CPN apart from PAN. Symptomatic treatment with judicial use of systemic steroids and anti-inflammatory agents will suffice in most cases.

Humans↗
PubMed1998

Occupational chromate allergy in Singapore: a study of 87 patients and a review from 1983 to 1995.

BACKGROUND: The prevalence of chromate allergy among all patients tested at the Contact and Occupational Dermatoses Clinic at the National Skin Centre in Singapore had fallen progressively from 1983 to 1989. Chromate has also become a less common occupational allergen because of the decline in the number of cases of allergic contact dermatitis from cement. OBJECTIVE: The aim of this report was to study and update the epidemiology of occupational chromate allergy among workers seen in a tertiary dermatology referral centre in Singapore from 1990 to 1995 and to review the changing trends of occupational chromate allergy in our local setting since 1983. The occurrence of concomitant contact allergens among was also studied. METHODS: All patients diagnosed to have occupational allergic contact dermatitis together with positive reactions to chromate, at the Joint Occupational Dermatosis Clinic at the National Skin Centre in Singapore, between January 1990 to December 1995, were included. Causes of chromate allergy and frequency of occurrence of concomitant contact allergens among construction and nonconstruction workers were compared. RESULTS: Eight hundred and fifty workers were seen during the 6-year-study period. Six hundred and thirty three (74.5%) were diagnosed to have occupational contact dermatitis, of which 257 (40.6%) had allergic contact dermatitis. Eighty-seven (33.8%) of these workers had positive reaction to chromate on patch testing. Ninety-five percent of these workers were men with a mean age of 33.4 years. The construction industry contributed 59% of the workers with chromate allergy. Cement (61%) remained the most common source of chromate allergy in our workers, and chromate from sources other than cement (39%) accounted for the rest. Of workers allergic to chromate from cement, 96% (51 of 53) came from the construction industry. Sixty percent of the workers with chromate allergy had concomitant contact allergens and the coexistence of two or more allergens was significantly more common among nonconstruction workers (53%) than construction workers (22%). The three most common concomitant contact allergens were cobalt (28%), rubber chemicals (21%) and nickel (18%). Nonconstruction workers had significantly higher rates of nickel allergy (36% v 6%) than construction workers (P < .03). Simultaneous reactivity to cobalt and nickel was also significantly more common among nonconstruction workers (22%) than construction workers (6%) (P < .03). CONCLUSION: Chromate has progressively become a less common occupational allergen at the National Skin Centre in Singapore from 1983 to 1989, because of a progressive fall in the number of cases of allergic contact dermatitis from cement. However, our study showed that occupational chromate allergy had now increased from 1990 to 1995, because of an increase in chromate allergy from sources other than cement. Chromate allergy from cement is declining, although still frequent, and sources other than cement are increasing in recent years. Concomitant nickel allergy, as well as simultaneous nickel and cobalt allergies, were more common among nonconstruction workers than construction workers.

Adult↗
PubMed1998

Sunscreen allergy in Singapore.

We report the epidemiology of sunscreen allergy over a period of 5 years at the National Skin Centre. A total of 61 patients with suspected allergy to sunscreen underwent patch or photopatch testing to our sunscreen series from 1992 to 1996. The results were retrospectively analysed and evaluated. Out of these 61 patients, 5 were found to have positive patch test reactions to sunscreens. 2 were photoallergic, and 3 were allergic to active ingredients in sunscreens. The main causative allergens were 2-ethylhexyl-4-methoxycinnamate (Parsol MCX) and 2-hydroxy-4-methoxybenzophenone (oxybenzone). We conclude that sunscreen contact allergy is uncommon in our practice.

Adult↗
PubMed1998

Allergic contact dermatitis to epoxy resin in a hemodialysis cannula.

A patient with chronic renal failure on hemodialysis presented with dermatitis, particularly over the arteriovenous fistulae sites on the forearm. Patch testing revealed a positive reaction to epoxy resin present in the glue that fixed the needle of the hemodialysis cannula.

Allergens↗
PubMed1998

Corticosteroid contact hypersensitivity screening in Singapore.

BACKGROUND: Topical corticosteroids have been in use since 1957. Two percent to 5% of patients attending patch test (PT) clinics have problems with corticosteroid contact hypersensitivity. Controversies abound with regard to the choice of steroids in the standard battery, the method of patch testing and reading, and the ideal concentration and vehicle. OBJECTIVE: To assess betamethasone 17-valerate (1% pet.), fluocinolone acetonide (0.25% petrolatum [pet.]), and tixocortol pivalate (1% pet.) used in the authors' standard battery. METHODS: Data were analyzed for patients seen between January 1994 and December 1996 who had positive PT reactions to one or more of these steroids. RESULTS: 3,603 patients had standard PTs, of which 20 had positive reactions to one or more of these steroids. There were three positive reactions to betamethasone 17-valerate, 17 to tixocortol, and none to fluocinolone. On further patch testing to the authors' steroid battery, only one tixocortol-positive patient had a positive reaction to hydrocortisone (1% ethanol/ dimethyl sulfoxide [DMSO]). CONCLUSIONS: Corticosteroid allergy is found to be relatively uncommon in Singapore on the basis of this screening series. The frequency of negative reactions to fluocinolone acetonide is sufficiently low for this corticosteroid to be excluded from the authors standard series. The significance of positive tixocortol reactions remains unknown. From the review of other relevant literature, the authors recommend that budesonide be added to their present series. Testing betamethasone 17-valerate in 1% ethanol may yield more positive allergic reactions. Individuals with a positive allergic PT reaction to one corticosteroid should subsequently be tested to a full corticosteroid series.

Administration, Topical↗
PubMed1997

Effectiveness of low-dose ASA in prevention of secondary ischemic stroke, the ASA Study Group in Taiwan.

This randomized double-blind controlled study was carried out to investigate the effect of 100 mg acetylsalicylic acid (ASA) per day on the secondary prevention of ischemic stroke. Patients who suffered a first ischemic stroke from 13 participating hospitals were enrolled. They were independent or only partially dependent in activities of daily living and all had received brain CT for diagnosis. Eligible patients were randomly allocated to the 100 mg ASA or the nicametate citrate (a vasodilator) groups, and trial medications were started within three to six weeks after the onset of stroke. The primary end point was cerebral reinfarction, and intracranial hemorrhage was classified as an adverse event. Four hundred and sixty-six patients participated in this study; and 222 cases (136 males and 86 females) were allocated to the ASA group while 244 cases (150 males and 94 females) were assigned to the nicametate group. No significant difference in baseline characteristics between the two groups was observed. Cerebral reinfarction developed 6.3% (14/222) in the ASA group and 11.9% (29/244) in the nicametate group. According to the Cox's proportional hazards model, the estimated risk ratio (ASA group vs. nicametate group) was 0.538, with a 95% confidence interval of 0.284-1.019. The result was of borderline statistical significance. The risk for cerebral reinfarction was reduced by almost 50% among those who took 100 mg ASA versus those who took nicametate.

Aged↗
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

Subtypes of ischemic stroke. A hospital-based stroke registry in Taiwan (SCAN-IV).

BACKGROUND AND PURPOSE: To better understand the clinical pattern and further elucidate the risk factors and outcome in different subtypes of cerebral infarction (CI) of the Chinese in Taiwan, we analyzed the National Taiwan University Hospital Stroke Registry in 1995 and performed an ethnic comparison with similar data banks. METHODS: From the National Taiwan University Hospital Stroke Registry in 1995, 676 patients (383 men and 293 women; mean age, 64.9 years; SD, 13.8 years; range, 1 to 98 years) with CI were recruited for this analysis. CI was classified into five subtypes based on clinical manifestations, ultrasonographic studies, and neuroimaging findings: large-artery atherosclerosis, lacunae, cardioembolism, other less common determined causes, and undetermined cause. Vascular risk factors, extracranial carotid artery atherosclerosis, and 30-day case-fatality rates were investigated in each subtype of CI. RESULTS: Of all CI patients, 17%, 29%, 20%, 6%, and 29% were classified as large-artery atherosclerosis, lacunae, cardioembolism, other determined causes, and undetermined cause subtypes, respectively. The present results were compared with those from eight similar Western stroke registries. The relative incidence of lacunar CI in Chinese patients was more common, but large-artery atherosclerotic CI was less common than in whites. Hypertension was frequently seen in CI patients, especially in those with lacunae (85%) and large-artery atherosclerosis (69%). Patients with cardioembolism had a higher percentage of atrial fibrillation (69%), left ventricular hypertrophy, and ischemic heart disease than the other patients. Patients with large-artery atherosclerosis had more vascular risk factors, such as hypertension, diabetes mellitus, smoking, and carotid stenosis. Cardioembolic patients had higher case-fatality rates than other CI patients. Of the cardioembolic patients, 17.3% and 21.8% died within 30 days and during hospitalization, respectively. CONCLUSIONS: The proportion of CI subtypes varied in different stroke registries. This may be partly due to applied classification criteria and racial-ethnic differences. Awareness of the risk factors and outcome in each subtype of stroke may afford further insights into the surveillance and treatment of cerebrovascular disease.

Adolescent↗
PubMed1997

Cocaine use during pregnancy: sensitive detection by hair assay.

OBJECTIVES: This paper compares the sensitivity of two tests of cocaine use, interview and urine test, with that of a radioimmunoassay of hair. METHODS: Interviews and hair samples were provided by 397 obstetric patients in one New York City hospital; urine samples were obtained in 377. Of these patients, 241 were receiving prenatal care (were registered) and 156 delivered without prenatal care (were unregistered). The 241 registered patients were derived from 400, comprising all reporting use of cocaine ever ("ever-users"), all reporting use by the father but not themselves ("lifestylers"), and a sample of women who were neither ever-users nor lifestylers. The 156 unregistered patients were derived from 352 women interviewed at delivery, unselected for reported use. RESULTS: Thirty-two percent reported ever using cocaine, 45% of these within 6 months before interview. Urine tests were positive in 20%, hair tests in 59%. The estimated sensitivity of the hair test (92%) was 3.1 times higher than that of the urine test (95% confidence interval [CI] = 2.5, 3.8) and 4 times higher than that of reported use in the past 6 months (95% CI = 3.2, 5.0). CONCLUSIONS: Self-report and urine tests alone miss most of cocaine users during pregnancy. Hair tests greatly improve detection and thus can enhance evaluations of the effects of prenatal cocaine use on fetal and child development.

Cocaine↗
PubMed1996

A case of adult onset Still's disease presenting with fever and a rash.

Adult onset Still's disease is a rare condition presenting with high spiking fever, transient maculopapular rash, myalgias, polyarthralgias or arthritis, lymphadenopathy, hepatosplenomegaly and a sore throat, associated with leucocytosis and neutrophilia. Early diagnosis is difficult because clinical features are non-specific. We report a 33-year-old Chinese female with this condition who presented with recurrent high spiking fever and rash over a 4-month period. We highlight the sequence of events leading to this diagnosis with emphasis on the cutaneous changes.

Adult↗
PubMed1995

Video-assisted thoracoscopic surgery in the paediatric population.

OBJECTIVE: Video-assisted thoracoscopic surgery (VATS) is now widely practised in adults but there are few publications on its application in the paediatric population. METHODOLOGY: Retrospective review of the authors' experience with VATS in children under 16 years old during an 18 month period in a university teaching hospital. RESULTS: From September 1993 to March 1994, VATS was attempted in 14 patients. Five were unsuccessful because of pleural symphysis or inability to collapse the upper lung. Ten cases of VATS were successfully performed in the remaining nine patients (eight males, one female; age range from 22 days to 15 years old). These included two drainages and limited decortications for loculated pleural effusion, one guided drainage of pericardial effusion, one thymectomy for thymic hyperplasia, three wedge resections for metastatic pulmonary osteosarcoma and three bleb excisions and pleurodesis for primary spontaneous pneumothoraces. There were no intra-operative complications. There was one death from dysrhythmia following an uneventful wedge resection. The mean duration of chest tube drainage was 1.4 days and postoperative hospital stay 2.6 days excluding two patients who stayed for further medical treatment. CONCLUSION: VATS is a useful approach in selected cases but further development of this approach awaits refinement of anaesthetic technique and endoscopic instrumentation.

Adolescent↗
PubMed1995

Impact of alcohol consumption and cigarette smoking on stroke among the elderly in Taiwan.

BACKGROUND AND PURPOSE: We investigated the influence of alcohol consumption and cigarette smoking on all types of stroke and cerebral infarction, in particular among a representative sample of elderly residents in Taiwan. METHODS: This study was a component of a nationwide survey of health and living status of residents aged 65 years or older in Taiwan in which subjects received detailed physical, neurological, and laboratory examinations. Inquiries were made about medical history, and information on the amount and duration of drinking and smoking was obtained. Diagnoses of stroke were made according to the results of brain computed tomography at the onset of disease or were based on criteria established by the World Health Organization. RESULTS: Of the 2600 subjects, there were 155 elderly persons with stroke (prevalence, 6%). Excessive drinking of more than 367.6 g/wk of alcohol was associated with a high prevalence of cerebral infarction. Consumption of < or = 367.5 g/wk of alcohol did not have an influence on stroke prevalence. The relationship between duration of alcohol drinking and stroke was equivocal. More than 30 pack-years of cigarette smoking was a significant risk factor for all types of stroke and cerebral infarction in particular. Using multiple logistic regression to control for possible confounders, it was found that smoking was an independent risk factors for all stroke and was of borderline significance for cerebral infarction. Although excessive drinking was a significant risk factor for cerebral infarction in univariate analysis, this effect was lost after adjustment for other confounders. CONCLUSIONS: Cigarette smoking was a more important risk factor for stroke and cerebral infarction than excessive drinking of alcohol.

Aged↗
PubMed1995

Toward fully automated genotyping: genotyping microsatellite markers by deconvolution.

Dense genetic linkage maps have been constructed for the human and mouse genomes, with average densities of 2.9 cM and 0.35 cM, respectively. These genetic maps are crucial for mapping both Mendelian and complex traits and are useful in clinical genetic diagnosis. Current maps are largely comprised of abundant, easily assayed, and highly polymorphic PCR-based microsatellite markers, primarily dinucleotide (CA)n repeats. One key limitation of these length polymorphisms is the PCR stutter (or slippage) artifact that introduces additional stutter bands. With two (or more) closely spaced alleles, the stutter bands overlap, and it is difficult to accurately determine the correct alleles; this stutter phenomenon has all but precluded full automation, since a human must visually inspect the allele data. We describe here novel deconvolution methods for accurate genotyping that mathematically remove PCR stutter artifact from microsatellite markers. These methods overcome the manual interpretation bottleneck and thereby enable full automation of genetic map construction and use. New functionalities, including the pooling of DNAs and the pooling of markers, are described that may greatly reduce the associated experimentation requirements.

Algorithms↗
PubMed1995

An unusual drug eruption to ampicillin.

The authors describe an unusual presentation of ampicillin allergy. A 24-year-old Chinese man noted localized pustular skin eruptions on his cheeks each time he ingested ampicillin. These eruptions would subside spontaneously within a week after stopping use of ampicillin. Drug provocation with ampicillin reproduced the same eruption in exactly the same sites. The eruptions were different clinically and histologically from fixed drug eruptions. The mechanism of such eruption is unknown.

Adult↗