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  1. Tan WC, Chan LC
    Med J Malaysia, 2011 Oct;66(4):383-4.
    PMID: 22299569
    Kaposi's sarcoma (KS) is strongly associated with Human Herpes Virus 8 (HHV8) and Human Immunodeficiency Virus infection (HIV). It was the first malignancy to be linked with Acquired Immunodeficiency Syndrome (AIDS). We report a case of Kaposi's sarcoma in a newly diagnosed retroviral homosexual patient with CD4 count of 21. He had multiple firm discrete violaceous plaques and nodules scattered over the face, scalp, hard palate, trunk and genitalia. Biopsy of a skin nodule over the trunk and a biopsy of a lesion from the gastric mucosa confirmed Kaposi's sarcoma. He was started on Highly Active Antiretroviral Therapy (HAART) and cryotherapy (liquid nitrogen) was given for the lesions over the skin. He responded well to treatment. Liquid nitrogen is a useful adjuvant treatment for Kaposi's sarcoma.
  2. Ng TP, Tan WC
    Sleep Med, 2005 Nov;6(6):523-9.
    PMID: 16271696
    BACKGROUND AND PURPOSE: To investigate the prevalence and determinants of daytime sleepiness in an Asian multi-ethnic population. Cross-sectional survey based on a questionnaire in multi-ethnic Asian adult population of Singapore (2.4 million).
    PATIENTS AND METHODS: Measured frequency of excessive daytime sleepiness (EDS), socio-demographic status, sleep duration, perceived sleep insufficiency, frequent awakenings, difficulty falling asleep, snoring, breathing pauses, GHQ-12, shift work, solvent exposure at work, substance use, medications, and chronic diseases in random sample of 2,298 adults, aged 20-74 years, representing Chinese, Malays and Indians.
    RESULTS: Among the respondents, 10.8% reported usually feeling sleepy in the daytime, and 9.0% were classified as having EDS. Marked ethnic difference was observed, with higher rates of EDS in Malays and Chinese, compared to Indians. Increased risk of EDS was associated with perceived sleep insufficiency; snoring and breathing pauses; shift work and solvent exposure at work; psychiatric morbidity and chronic diseases, particularly chronic rhinitis; and medications with sedating effects.
    CONCLUSIONS: Daytime sleepiness is associated with a multiplicity of highly prevalent risk factors in the community, including sleep behavior, breathing-, work- and medically related factors. Significant ethnic differences, which were not explained by these factors, were observed between Chinese, Malays and Indians.
  3. Ng TP, Tan WC
    Thorax, 1999 Nov;54(11):990-4.
    PMID: 10525557
    BACKGROUND: A study was undertaken to examine temporal trends and ethnic differences in the asthma mortality rate in Singapore.
    METHODS: Asthma mortality rates in Singapore were estimated from vital data for the years from 1976 to 1995. Trends in sex and age specific (5-14, 15-34, 35-59, 60+ years) rates were obtained for four periods (1976-80, 1981-85, 1986-90, 1991-95) and for Chinese, Malay, and Indian subjects for the years when these data were available (1989-95).
    RESULTS: An increase in asthma mortality was observed in children aged 5-14 years from 0.21 per 100,000 person years in 1976-80 to 0.72 per 100,000 person years in 1991-95. No increases were noted in the other age groups but a small decrease was observed in the 1991-95 period for the 35-59 year age group. Marked ethnic differences in mortality rates were observed. In the group aged 5-34 years the asthma mortality rates were 0.5 per 100,000 in Chinese subjects, 1.3 per 100,000 in Indians, and 2.5 per 100,000 in Malay subjects. Similar 2-4 fold differences were observed in all other age groups.
    CONCLUSIONS: Apart from genetic factors, environmental exposures and medical care factors which influence asthma prevalence and severity are most likely to be the causes of the observed temporal trends and ethnic differences in the asthma mortality rate in Singapore, but further studies are needed to elucidate these more fully.
  4. Ng ZX, Tan WC
    J Food Sci Technol, 2017 Nov;54(12):4100-4111.
    PMID: 29085153 DOI: 10.1007/s13197-017-2885-0
    This study aimed to investigate the effect of four cooking methods with different durations on the in vitro antioxidant activities of five edible mushrooms, namely Agaricus bisporus, Flammulina velutipes, Lentinula edodes, Pleurotus ostreatus and Pleurotus eryngii. Among the raw samples, A. bisporus showed the highest total antioxidant activity (reducing power and radical scavenging), total flavonoid, ascorbic acid and water soluble phenolic contents. Short-duration steam cooking (3 min) increased the total flavonoid and ascorbic acid while prolonged pressure cooking (15 min) reduced the water soluble phenolic content in the mushrooms. The retention of antioxidant value in the mushrooms varied with the variety of mushroom after the cooking process. The cooking duration significantly affected the ascorbic acid in the mushrooms regardless of cooking method. To achieve the best antioxidant values, steam cooking was preferred for F. velutipes (1.5 min), P. ostreatus (4.5 min) and L. edodes (4.5 min) while microwave cooking for 1.5 min was a better choice for A. bisporus. Pressure cooked P. eryngii showed the best overall antioxidant value among the cooked samples. Optimised cooking method including pressure cooking could increase the antioxidant values in the edible mushrooms.
  5. Yong FL, Tan WC
    Med J Malaysia, 2024 Mar;79(2):191-195.
    PMID: 38553925
    INTRODUCTION: An expanded access program (EAP) is a regulatory mechanism that provides access to an investigational drug, which is not approved for use, in treating life-threatening conditions when all the standard-ofcare treatments are exhausted.

    MATERIALS AND METHODS: An online, anonymous, voluntary survey was conducted to assess the level of knowledge and understanding about EAPs among Malaysian oncologists using SurveyMonkey® between April 2020 and June 2020. Oncologists who had enquired about EAP in the past, were invited at random to participate in the survey. Participants who did not provide consent or failed to complete the survey were excluded.

    RESULTS: A total of 15 oncologists participated in the survey, from both public (46.6%) and private (46.6%) practices. Most respondents (80%) had filed between 1 to 10 EAP applications in the past 12 months. For 73.3% respondents, resources or training were not provided for EAPs from institutions. Around 53% of the respondents reported that their knowledge of EAPs and application processes including country regulations is 'good'. The majority of respondents (73.3%) reported that the educational modules on an overview of EAPs, country regulations and the EAP application process will be beneficial. Most participants received information about the existing EAPs either by reaching out to a pharmaceutical sponsor or through another health care provider and some received information about the existing EAPs through their institutions or patients/caregivers. Most of the respondents recommended that pharmaceutical companies should have readily available information related to the availability and application of EAPs for all pipeline products on their websites.

    DISCUSSION: EAPs are crucial treatment access pathways to provide investigational drugs to patients who have exhausted their treatment options and are not eligible for participation in clinical trials. Malaysian oncologists have a fair understanding about the EAPs and the application processes.

    CONCLUSION: Additional training and awareness are needed for Malaysian oncologists to upscale the utilisation of EAPs.

  6. Ng TP, Tan WC
    Ann Acad Med Singap, 1994 Jan;23(1):83-8.
    PMID: 8185279
    We conducted a population-based study involving a stratified cluster disproportionate random sample of 2868 adults aged 20 to 74 years selected from five housing estates (Yishun, Toa Payoh, Jurong East, Geylang/Eunos and Bukit Merah). Chronic rhinitis was defined as the usual presence of symptoms of blocked or running nose, apart from colds or the flu, lasting for more than a year. Allergic rhinitis was considered to be present if these symptoms were associated with conjunctivitis or recognisable provocation by commonly known allergens, namely house dust, dogs, cats, birds, pollen, or medicines. The estimated general population prevalence of chronic rhinitis was 10.8% (95% confidence interval (CI) 8.8-12.7). Higher prevalences were noted in males, in younger adults, in Indians and Chinese, in those with higher socio-economic status, and in Toa Payoh, Jurong East and Geylang/Eunos. The prevalence of allergic rhinitis was 5.5% (95% CI 4.5-6.5). The most common 'allergenic' factor in allergic rhinitis was house dust (73%); provocation by birds, cats or dogs (5%), grass or tree pollens (5%), and medicine (5%) was less common but likely to have been under-recognised. Provocation by change in temperature (54%) and early in the morning (64%) was equally frequent in both 'allergic' and 'non-allergic' rhinitis; cigarette smoke, petrol and diesel fumes, food and work environment were less common (4-12%). Allergic rhinitis was highly significantly associated with asthma (13.9% in allergic rhinitis, 4.4% in non-allergic rhinitis, and 2.2% in non-rhinitic subjects).
  7. Ng TP, Seow A, Tan WC
    Eur Respir J, 1998 Jul;12(1):198-203.
    PMID: 9701437
    This study investigated the prevalence of snoring and symptoms of sleep breathing-related disorders in the multi-ethnic population of Singapore (3 million people, comprising 75% Chinese, 15% Malay and 7% Indian). A multistaged, area cluster, disproportionate stratified, random sampling of adults aged 20-74 yrs was used to obtain a sample of 2,298 subjects (65% response), with approximately equal numbers of Chinese, Malay and Indian and in each 10 yr age group. An interviewer-administered field questionnaire was used to record symptoms of snoring and breathing disturbances during sleep witnessed by a room-mate and other personal and health-related data. The weighted point estimate (and 95% confidence interval) of the whole population prevalence of snoring was 6.8% (53-83). There were pronounced ethnic differences among Chinese, 6.2% (4.4-8.1); Malay, 8.1% (6.1-10.2) and Indian, 10.9% (85-13.4). The minimum whole population prevalence by the most restricted symptom criteria for defining sleep breathing-related disorder was 0.43% (0.05-0.8%). Similar marked ethnic differences in rates were observed using various symptom criteria. The ethnic differences in sleep breathing symptoms paralleled the differences in body mass index, neck circumference and hypertension, but statistically significant differences remained after adjustment for sex, age and these known associated factors. Marked ethnic differences in snoring and sleep breathing-related disorders were observed in Chinese, Malays and Indians in Singapore, which were only partly explained by known factors of sex, age and body habitus.
  8. Ng TP, Hui KP, Tan WC
    Thorax, 1994 Apr;49(4):347-51.
    PMID: 8202905
    BACKGROUND: The prevalence and morbidity of asthma vary greatly among different ethnic communities and geographical locations, but the roles of environmental and genetic factors are not fully understood. The differences in prevalence of adult asthma among Chinese, Malay, and Indian ethnic groups in Singapore were examined, and the extent to which these could be explained by personal and environmental factors were investigated.
    METHODS: A stratified disproportionate random sample (n = 2868) of Chinese (n = 1018), Malays (n = 967), and Indians (n = 883) of both sexes was drawn from households in five public housing estates, and an interviewer administered questionnaire was used to determine cumulative and current prevalence of "physician diagnosed asthma" (symptoms with a physician diagnosis of asthma).
    RESULTS: Lifetime cumulative prevalence (standardised to the general population) of "physician diagnosed asthma" was 4.7% in men and 4.3% in women; 12 month period prevalences were 2.4% and 2.0%, respectively. Cumulative prevalence of asthma was significantly higher in Indians (6.6%) and Malays (6.0%) than in Chinese (3.0%); period prevalences of asthma were 4.5% in Indians, 3.3% in Malays, and 0.9% in Chinese. Ownership of cats or dogs was more frequent in Malays (15.4%) and Indians (11.2%) than in Chinese (8.8%). Rugs and carpets were also more frequently used by Malays (52.2%) and Indians (40.7%) than by Chinese (8.9%). Current smoking prevalences were higher in Malays (27.3%) than in Indians (19.4%) and Chinese (23.0%). Malays and Indians did not have higher rates of atopy (11.1% and 15.2%, respectively) than Chinese (15.4%). Adjustment for these factors in multivariate analyses reduced the greater odds of asthma in Malays and Indians, but not to a significant extent.
    CONCLUSIONS: There are ethnic differences in the prevalence of asthma in Singapore which are not entirely explained by differences in smoking, atopy, or other risk factors. Other unmeasured environmental factors or genetic influences are likely to account for residual differences in the prevalence of asthma.
  9. Tan WC, Mat Isa NA
    PLoS One, 2016;11(9):e0162985.
    PMID: 27632581 DOI: 10.1371/journal.pone.0162985
    In human sperm motility analysis, sperm segmentation plays an important role to determine the location of multiple sperms. To ensure an improved segmentation result, the Laplacian of Gaussian filter is implemented as a kernel in a pre-processing step before applying the image segmentation process to automatically segment and detect human spermatozoa. This study proposes an intersecting cortical model (ICM), which was derived from several visual cortex models, to segment the sperm head region. However, the proposed method suffered from parameter selection; thus, the ICM network is optimised using particle swarm optimization where feature mutual information is introduced as the new fitness function. The final results showed that the proposed method is more accurate and robust than four state-of-the-art segmentation methods. The proposed method resulted in rates of 98.14%, 98.82%, 86.46% and 99.81% in accuracy, sensitivity, specificity and precision, respectively, after testing with 1200 sperms. The proposed algorithm is expected to be implemented in analysing sperm motility because of the robustness and capability of this algorithm.
  10. Lee SW, Loo CH, Tan WC
    Med J Malaysia, 2018 10;73(5):338-339.
    PMID: 30350820 MyJurnal
    Confluent and reticulated papillomatosis (CRP) was first described in 1927 by Gougerot and further characterised by Carteud.1 It is relatively rare, and the exact pathophysiology was not well known. Over the years, multiple treatment modalities were proposed. We report our experience with three cases of CRP which showed complete clearance with tetracycline group of antibiotics.
  11. Tan WC, Jaganath IB, Manikam R, Sekaran SD
    Int J Med Sci, 2013;10(13):1817-29.
    PMID: 24324358 DOI: 10.7150/ijms.6902
    Nucleoside analogues such as acyclovir are effective antiviral drugs against herpes simplex virus infections since its introduction. However, with the emergence of acyclovir-resistant HSV strains particularly in immunocompromised patients, there is a need to develop an alternative antiherpetic drug and plants could be the potential lead. In this study, the antiviral activity of the aqueous extract of four Phyllanthus species were evaluated against herpes simplex virus type-1 (HSV-1) and HSV-2 in Vero cells by quantitative PCR. The protein expressions of untreated and treated infected Vero cells were studied by 2D-gel electrophoresis and Western blot. This is the first study that reported the antiviral activity of P. watsonii. P. urinaria was shown to demonstrate the strongest antiviral activity against HSV-1 and HSV-2, with SI >33.6. Time-of-addition studies suggested that the extract may act against the early infection stage and the replication stage. Protein expression studies indicated that cellular proteins that are involved in maintaining cytoskeletal structure could be potential target for development of antiviral drugs. Preliminary findings indicated that P. urinaria demonstrated potent inhibitory activity against HSV. Hence, further studies such as in vivo evaluation are required for the development of effective antiherpetic drug.
  12. Ong CK, Tan WC, Chan LC, Abdul Razak M
    Med J Malaysia, 2012 Apr;67(2):222-3.
    PMID: 22822651 MyJurnal
    Epidermal growth factor receptor (EGFR)--tyrosine kinase inhibitors (TKI) like erlotinib and gefitinib have been approved as monotherapy for the treatment of patients with locally advanced or metastatic non small cell lung cancer (NSCLC) after failure of at least one prior chemotherapy regimen. The use of EGFR-TKI is associated with unique and dramatic dermatologic side effects. We report 2 patients with NSCLC developing a typical acneiform (papulo-pustular) eruption shortly after initiation of EGFR-TKI.
  13. Tan WC, Ong CK, Lo KS, Leong KN
    Med J Malaysia, 2007 Aug;62(3):251-3.
    PMID: 18246920 MyJurnal
    Pyoderma Gangrenosum (PG) is a non-infective, necrotising neutrophilic dermatosis. Many diseases may mimic PG. It may be idiopathic or may be associated with a systemic disorder. We report a case of PG in association with ulcerative colitis.
  14. Tan WC, Ong CK, Kang SC, Razak MA
    Med J Malaysia, 2007 Jun;62(2):143-6.
    PMID: 18705448 MyJurnal
    First line Anti-TB therapy with rifampicin, isoniazid, pyrazinamide, and ethambutol/streptomycin is very effective. However, major adverse reactions to antituberculous drugs can cause significant morbidity and mortality. Cutaneous adverse drug reaction (CADR) is one of the commonly observed major adverse events. This retrospective study looked at the cases of TB treated in Respiratory Unit, Penang Hospital from January 2004 to December 2005. Of 820 patients treated for active TB, 47 patients (25 females; 22 males) developed CADR (5.7%). CADRs observed include morbiliform rash (72.3%), erythema multiforme syndrome (8.5%), urticaria (8.5%) and others (which include exfoliative dermatitis and lichenoid eruption). Ninety-seven percent of events occurred within two months after the initial dose. Incidence rate of CADR among the first line anti-TB drugs, pyrazinamide was the commonest offending drug (2.38%), followed by streptomycin (1.45%), ethambutol (1.44%), rifampicin (1.23%) and isoniazid (0.98%). Various clinical characteristics of patients with CADR identified include Human Immunodeficiency Virus (HIV) infection (27.7%), polypharmacy (21.3%), elderly (19.1%), autoimmune disorders (6.4%), pre-existing renal impairment (4.3%), pre-existing liver disorders (4.3%). In conclusion, CADR is common and majority of cases occurred within two months after initiation of anti-TB treatment, particularly in HIV infected patients. Pyrazinamide is the commonest offending drug.
  15. Loo CH, Chan YC, Lee KQ, Tharmalingam P, Tan WC
    Med J Malaysia, 2015 Jun;70(3):177-81.
    PMID: 26248781 MyJurnal
    INTRODUCTION: Psoriasis is a common, chronic, relapsing, immune-mediated inflammatory disease. Our objective is to review the clinical profile, co-morbidities, and outcome of patients with psoriasis.
    METHODS: This is a cross-sectional study of outpatient psoriasis patients attending the dermatology clinic, Hospital Sultan Abdul Halim (HSAH) between January 2012 and June 2014. Data collection was based on Malaysian Psoriasis Registry.
    RESULTS: Among 296 patients with psoriasis, Malays were the most common 175 (59.1%), followed by Indians 82 (27.7%), Chinese 37 (12.5%) and others 2 (0.6%). Male to female ratio was 1.2:1. More than half (54.7%) of the patients had early onset disease (age 40 or less). Only 26 patients (8.8%) have positive family history. The most common clinical presentation was chronic plaque psoriasis (89.9%), followed by erythrodermic psoriasis (4.7%), guttate psoriasis (3.0%) and pustular psoriasis (1.7%). Twenty eight percent had nail involvement while arthropathy was seen only in 14.7%. Common triggers were sunlight (46.0%), stress (31.1%), trauma (5.4%), food (4.0%), pregnancy (4.0%), and upper respiratory tract infections (2.7%). Co-morbidities observed include ischaemic heart disease (7.1%), hypertension (26.7%), dyslipidemia (17.6%), and diabetes mellitus (22.0%). All patients were on topical medications. About 6.8% of the patients were treated with phototherapy. One third of patients (35.5%) were given systemic therapy. Out of these, 84 patients (80.0%) were on methotrexate while only 16 (15.2%) on acitretin. None was on cyclosporine or biologic. In term of disease severity, 41.7% of patients had BSA >10% and 31.4% patients had DLQI > 10.
    CONCLUSION: Our patients show a similar clinical profile and outcome as our Malaysian psoriasis population. However they tend to have a more severe disease. There is a need for a more effective targeted therapy for a better outcome.
    Study site: Dermatology clinic, Hospital Sultan Abdul Halim (HSAH), Sungai Petani, Kedah, Malaysia
  16. Chin NK, Ng TP, Hui KP, Tan WC
    Respirology, 1997 Jun;2(2):143-9.
    PMID: 9441128 DOI: 10.1111/j.1440-1843.1997.tb00070.x
    Ethnic differences in lung function are well recognized, hence the use of normative data should therefore be based on reference equations that are derived specifically for different ethnic groups. We have collected data (n = 406) for population-based reference values of lung function from randomly selected samples of healthy non-smoking adults of both gender (aged 20-79 years) for each of the three major ethnic groups (Chinese, Malay and Indians) in Singapore. Lung function forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, diffusion capacity (transfer factor) for carbon monoxide (DLCO), total lung capacity (TLC), residual volume (RV), RV/TLC and functional residual capacity (FRC) was measured using standardization procedures and acceptability criteria recommended by the American Thoracic Society. Lung function values were predicted from age, height, weight, body mass index (BMI) and transformed variables of these anthropometric measures, using multiple regression techniques. Ethnic differences were demonstrated, with Chinese having the largest lung volumes and flow rates, and Indians the smallest. These prediction equations provide improved and additional (TLC, RV, RV/TLC, FRC) population-based reference values for assessment of pulmonary health and disease in Singapore.
  17. Yeoh CA, Chan CL, Chin CC, Tan WC
    Med J Malaysia, 2020 03;75(2):103-109.
    PMID: 32281589
    INTRODUCTION: Chlamydia trachomatis is one of the most common sexually transmitted diseases (STDs) globally. However, data on its prevalence and risk factors in Malaysia is still scarce.

    OBJECTIVE: We aimed to identify the prevalence and risk factors of genitourinary C.trachomatis infection among patients attending STD clinics in northern Peninsular Malaysia.

    METHODS: A hospital-based cross-sectional study was conducted in STD clinics of Hospital Pulau Pinang and Hospital Sultanah Bahiyah, Kedah from January to November 2014. Participants were individually interviewed using a structured data collection form followed by a physical examination and laboratory tests. Nucleic Acid Amplification Test (NAAT) was used to detect C.trachomatis infection. Analysis was carried out using SPSS Version 15.

    RESULTS: Eighty-three sexually active patients were enrolled, consisting of 51 males and 32 females. The median age was 28.0 years. In general, 32.5% patients were asymptomatic, the remaining presented with genital discharge (41.0%), genital warty lesion (25.3%), genital ulcer (13.3%), dysuria (13.3%), dyspareunia (2.4%), urine hesistancy (1.2%) and genital swelling (1.2%). The prevalence of genitourinary C.trachomatis infection was 21.7% in the study population; 17.6% in males and 28.1% in females. Among the infected females, 44.4% were pregnant. Of those infected 56.6% did not show any symptoms of genital infection, and 77.8% were aged between 18 and 30 years, of which most were females. Among newly diagnosed HIV patients, the prevalence was 14.3%. From multivariable logistic regression analysis, age under 28 years, being married and engagement in oral sex had significantly increased odds of C.trachomatis infection.

    CONCLUSIONS: C.trachomatis infection was common among patients attending STD clinics in northern Penisular Malaysia especially in the younger age groups. Majority of the infected patients were asymptomatic.

  18. Tham WP, Busmanis I, Tan WC, Kwek JW
    Med J Malaysia, 2016 Jun;71(3):144-6.
    PMID: 27495891
    Polypoid endometriosis is an uncommon variant of endometriosis which can mimic malignancy due to its presentation as masses. We present a case of polypoid endometriosis which simulated cervical malignancy both on clinical examination and on computed tomography (CT) scanning and discuss how magnetic resonance (MR) imaging, in particular Diffusion Weighted Imaging (DWI), can help to distinguish this condition from true malignancy and avoid invasive surgery.
  19. Tan WC, Kuppusamy UR, Phan CW, Sabaratnam V
    Int J Med Mushrooms, 2018;20(2):155-163.
    PMID: 29773007 DOI: 10.1615/IntJMedMushrooms.2018025445
    Ganoderma neo-japonicum is an annual polypore that grows on decaying bamboo in the forests of Malaysia. The indigenous Temuan tribe uses this species as a medicinal mushroom to cure fever and epilepsy and to improve body strength. The potential use of G. neo-japonicum in genoprotection and DNA repair was established using a single-cell gel electrophoresis (comet) assay. The effects of the ethanol and hot aqueous extracts from wild and cultivated basidiocarps, solid substrate-fermented (SSF) wheat grains, and mycelia via submerged culture on H2O2-damaged murine RAW264.7 macrophages were investigated. An ethanol extract from wild basidiocarps showed the most significant protective effect on murine RAW264.7 macrophages, followed by ethanol and hot water extracts of cultivated basidiocarps, and this effect was dose dependent. However, only the ethanol extracts from SSF and submerged culture showed significant protective effects compared with the control. As for DNA repair ability, only the ethanol extract from wild and cultivated basidiocarps showed significant results when compared with the negative control. The findings suggest the potential therapeutic use of G. neo-japonicum in genome protection and as a DNA repair stimulator.
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