Displaying publications 1 - 20 of 60 in total

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  1. Sreeramareddy CT, Chew WF, Poulsaeman V, Boo NY, Choo KB, Yap SF
    J Family Community Med, 2013 May;20(2):90-7.
    PMID: 23983560 DOI: 10.4103/2230-8229.114769
    BACKGROUND: Little is known about the relationship of blood pressure (BP) with adiposity indicators, dietary habits, physical activity, and sleep in school children in Malaysia. We aimed to study about the distribution of BP and its associated factors in primary school children.
    MATERIALS AND METHODS: A survey was carried out on a random sample of 335 children in five primary schools. BP was measured with a mercury sphygmomanometer. Anthropometry was done by standard methods. Demographic information, dietary habits, physical activity, and duration of sleep were collected by interviews. World Health Organization classification based on body mass index (BMI) and waist circumference (WC) cut-offs were used to define overweight/obesity. Elevated BP was defined according to US reference standards.
    RESULTS: A total 335 children (144 boys and 191 girls) were examined. Their mean age was 9.18 years (standard deviation [SD] = 0.28). Overall mean systolic blood pressure (SBP) and mean diastolic blood pressure (DBP) were 99.32 mmHg (SD = 10.79) and 67.11 mmHg (SD = 10.76), respectively. Mean BMI and WC were 16.39 (SD = 3.58) and 57.77 cm (SD = 8.98), respectively. The prevalence of pre-hypertension was 12.23% (95% confidence intervals [CIs] 8.73, 15.75) and hypertension was 13.4% (95% CIs 9.78, 17.09). Mean SBP and DBP was higher among overweight and obese children than normal children. By multivariate linear regression analyses, BMI (β = 0.250, P = 0.049) and WC (β = 0.308, P = 0.015) were positively associated with SBP; age (β = 0.111, P = 0.017), BMI (β = 0.320, P = 0.012) were positively associated with DBP but total (weekly) hours of sleep (β = -0.095, P = 0.037) was negatively associated with DBP.
    CONCLUSION: BP was associated with BMI and WC. Health promotion activities should be initiated in primary schools.
    KEYWORDS: Blood pressure; body mass index; cross-sectional survey; obesity; school children; waist circumference
  2. Nasir NM, Sthaneshwar P, Yunus PJ, Yap SF
    Malays J Pathol, 2010 Jun;32(1):21-6.
    PMID: 20614722 MyJurnal
    The objective of the study is to determine the level of agreement between measured total carbon dioxide (TCO2) and calculated bicarbonate (HCO3-) in our laboratory.
  3. Sthaneshwar P, Prathibha R, Yap SF
    Malays J Pathol, 2005 Jun;27(1):29-32.
    PMID: 16676690
    Thyrotoxic periodic paralysis (TPP) is a medical emergency characterised by sudden onset of muscle weakness with hypokalemia that resolves with the treatment of hyperthyroidism. We report three cases of thyrotoxic periodic paralysis seen at the Accident and Emergency Care Department, University of Malaya Medical Centre in a period of four months. We also review the clinical presentation, pathophysiology, biochemical features and management of TPP. All three patients were young Asian males, presenting with muscle weakness of sudden onset. The first patient presented with lower limb weakness and had symptoms of thyrotoxicosis and goitre. He had a previous similar episode which resolved spontaneously. The second patient presented with quadriplegia, respiratory acidosis and had no signs and symptoms of thyrotoxicosis. The electrocardiogram of this patient showed normal sinus rhythm with U wave in V3 and a flat T wave, which are characteristic of hypokalaemia. The third patient, who was a known case of thyrotoxicosis, was admitted thrice for hypokalemic paralysis during the study period. All cases had low serum potassium, suppressed TSH and elevated T4 confirming thyrotoxic periodic paralysis. Potassium therapy was useful during the crisis; however prophylactic potassium has not been shown to prevent attacks as seen in one of our cases.
  4. Yap SF
    Malays J Pathol, 2004 Jun;26(1):1-12.
    PMID: 16190102
    "Parenteral" or "serum" hepatitis is known to have afflicted man for centuries. However, it was not until the mid-1960s that the causative agent of this infection, the hepatitis B virus, was discovered. Since then, the biology and the replication strategy of the virus, and the clinical features and the epidemiology of the hepatitis B infection have been determined. Knowledge about the virus and the infection it causes led to the development of firstly, a plasma-derived vaccine and later a recombinant vaccine for the prevention of the infection. Integration of the hepatitis B vaccine into newborn vaccination programmes on a worldwide basis represents a major step in the effort to eliminate this infectious disease and its complications. Laboratory tests are available for the diagnosis and monitoring of the disease. Therapies have been developed to halt the progress of the chronic infection in affected individuals. While these developments have resulted in a decrease of the frequency of infection in many countries, particularly those that have implemented universal immunization of newborns, the chronic infection remains a significant global problem. Worldwide, over 300 million individuals are infected and each year, an estimated 1 million persons die from chronic complications of the disease including hepatocellular carcinoma and hepatic failure. The therapies currently available result in elimination of the virus in only a relatively small proportion of subjects and carry with it serious side effects. Geopolitical, economic and other factors hinder the vision of elimination of the infection through immunization programmes. Nevertheless, work continues to clarify further the underlying pathological mechanism of the infection, the host and viral factors that promote elimination or persistence of the virus in the human host. It is hoped that such investigations will reveal viral targets for the design of newer and potentially more effective drugs to treat the infection.
  5. Thong MK, Tan JA, Tan KL, Yap SF
    J Trop Pediatr, 2005 Dec;51(6):328-33.
    PMID: 15967770 DOI: 10.1093/tropej/fmi052
    beta-thalassaemia major, an autosomal recessive hemoglobinopathy, is one of the most common single gene disorders in multi-racial Malaysia. The control of beta-thalassaemia major requires a multi-disciplinary approach that includes population screening, genetic counselling, prenatal diagnosis and the option of termination of affected pregnancies. To achieve this objective, the molecular characterisation of the spectrum of beta-globin gene mutations in each of the affected ethnic groups is required. We studied 88 consecutive unrelated individuals and their respective families with beta-thalassaemia (74 beta-thalassaemia major, 12 HbE-beta-thalassaemia, 2 with HbE homozygotes) and four individuals with beta-thalassaemia trait that contributed a total 180 alleles for study. Using a 2-step molecular diagnostic strategy consisting of amplification refractory mutation system (ARMS) to identify the 8 most common mutations followed by other DNA-based diagnostic techniques, a total of 177 (98.3 per cent) of the 180 beta-thalassaemia alleles were characterised. One out of 91 (1 per cent) of the Chinese alleles, one out of 46 (2.2 per cent) Malay alleles and one out of two Indian alleles remained unknown. A 100 per cent success rate was achieved in studying the Kadazandusun community in this study. A strategy to identify beta-globin gene mutations in Malaysians with beta-thalassaemia is proposed based on this outcome.
  6. Thong MK, Rudzki Z, Hall J, Tan JA, Chan LL, Yap SF
    Hum Mutat, 1999;13(5):413.
    PMID: 10338100 DOI: 10.1002/(SICI)1098-1004(1999)13:5<413::AID-HUMU15>
    Beta-thalassemia major is one of the commonest genetic disorders in South-East Asia. The spectrum of beta-thalassemia mutations in the various ethnic sub-populations on the island of Borneo is unknown. We studied 20 Dusun children from the East Malaysian state of Sabah (North Borneo) with a severe beta-thalassemia major phenotype, using a combination of Southern analysis, polymerase chain reaction analysis and direct sequencing. We found the children to be homozygous for a large deletion, which has a 5' breakpoint at position -4279 from the cap site of the beta-globin gene (HBB) with the 3' breakpoint located in a L1 family of repetitive sequences at an unknown distance from the beta-globin gene. This was similar to a recent finding of a large deletion causing beta-thalassemia first described in unrelated beta-thalassemia heterozygotes of Filipino descent. This report describes the first 20 families with homozygosity of the deletion causing a severe phenotype. It provides the first information on the molecular epidemiology of beta-thalassemia in Sabah. This finding has implications for the population genetics and preventative strategies for beta-thalassemia major for nearly 300 million individuals in South-East Asia.
  7. Tan KL, Tan JA, Wong YC, Wee YC, Thong MK, Yap SF
    Genet. Test., 2001;5(1):17-22.
    PMID: 11336396 DOI: 10.1089/109065701750168626
    Beta-thalassemia major patients have chronic anemia and are dependent on blood transfusions to sustain life. Molecular characterization and prenatal diagnosis of beta3-thalassemia is essential in Malaysia because about 4.5% of the population are heterozygous carriers for beta-thalassemia. The high percentage of compound heterozygosity (47.62%) found in beta-thalassemia major patients in the Thalassaemia Registry, University of Malaya Medical Centre (UMMC), Malaysia, also supports a need for rapid, economical, and sensitive protocols for the detection of beta-thalassemia mutations. Molecular characterization of beta-thalassemia mutations in Malaysia is currently carried out using ARMS, which detects a single beta-thalassemia mutation per PCR reaction. We developed and evaluated Combine amplification refractory mutation system (C-ARMS) techniques for efficient molecular detection of two to three beta-thalassemia mutations in a single PCR reaction. Three C-ARMS protocols were evaluated and established for molecular characterization of common beta-thalassemia mutations in the Malay and Chinese ethnic groups in Malaysia. Two C-ARMS protocols (cd 41-42/IVSII #654 and -29/cd 71-72) detected the beta-thalassemia mutations in 74.98% of the Chinese patients studied. The CARMS for cd 41-42/IVSII #654 detected beta-thalassemia mutations in 72% of the Chinese families. C-ARMS for cd 41-42/IVSI #5/cd 17 allowed detection of beta-thalassemia mutations in 36.53% of beta-thalassemia in the Malay patients. C-ARMS for cd 41-42/IVSI #5/cd 17 detected beta-thalassemia in 45.54% of the Chinese patients. We conclude that C-ARMS with the ability to detect two to three mutations in a single reaction provides more rapid and cost-effective protocols for beta-thalassemia prenatal diagnosis and molecular analysis programs in Malaysia.
  8. Looi LM, Cheah PL, Yap SF
    Malays J Pathol, 1997 Jun;19(1):35-9.
    PMID: 10879240
    One hundred and twelve infiltrating ductal carcinoma of breast were studied by the standard avidinbiotin complex immunoperoxidase method on formalin-fixed, paraffin-embedded tissue sections, using a monoclonal antibody to c-erbB-2 oncoprotein. The same tumours were assessed and scored according to the Bloom and Richardson criteria into three histological grades. The distribution of tumours according to grade were: 8 Grade I, 34 Grade II and 70 Grade III. Forty-three (38.4%) tumours showed positive membrane staining for c-erbB-2 oncoprotein. These comprised 7 Grade II and 36 Grade III tumours with c-erbB-2 immunopositivity rates of 20.6% and 51.4% respectively. The oncoprotein was not expressed by Grade I tumours. This study shows a good correlation between c-erbB-2 expression and histological grade, a known prognostic indicator of invasive breast carcinoma. Because the c-erbB-2 oncogene has extensive structural homology to the epidermal growth factor receptor gene, its overexpression can be expected to result in more aggressive tumour behaviour. While it may be regarded as another indicator of poor prognosis breast cancers, its value in the selection of carcinomas less responsive to hormonal therapy and those more suitable for immunotherapy than chemotherapy has been mooted but remains to be clarified.
  9. Yap SF
    Malays J Pathol, 1994 Jun;16(1):3-6.
    PMID: 16329567
    Chronic hepatitis B virus (HBV) infection constitutes a major public health problem particularly in developing countries in East Asia, South-East Asia, the Pacific Basin and Africa. In Malaysia, a developing nation in the South East Asian region, the chronic HBV carrier rate varies between < 1% to about 10% depending on the ethnic group studied. The highest frequency is seen among the Chinese, followed by the Malays and lastly the Indians, with a male preponderance of between 2 : 1 and 3 : 1. Exposure to the virus among the adult population is estimated to be about 15%, 26% and 36% among the Indians, Malays and Chinese respectively. Serological study of adult chronic HBV carriers showed a frequency of HBe antigenemia of about 35%, with a significant decreasing trend with age. HBV DNA status generally correlated with the HBe status. An atypical profile of anti-HBe associated with serum HBV DNA is found in some carriers; in most instances, this is related to seroconversion from HBe antigenemia to anti-HBe. Chronic complications of HBV infection include the development of hepatocellular carcinoma (HCC), the occurrence of which closely parallel that of HBsAg carrier rate. In Malaysia, HCC is the third most common malignant neoplasm and among the 10 leading causes of death. About 80% of our HCC cases are HBV associated. All 3 ethnic groups are afflicted, the highest frequency being among the Chinese. Males show a disproportionate risk with an odds ratio of 3.93 (p < 0.0001).
  10. Cheah PL, Looi LM, Lin HP, Yap SF
    Cancer, 1990 Jan 1;65(1):174-6.
    PMID: 2152851
    In the 7-year period between 1980 and 1987, six cases of childhood primary hepatocellular carcinoma (PHC) were confirmed histologically in our institution. Hepatitis B surface antigen (HBsAg) seropositivity was confirmed in five of the cases, and tissue HBsAg was shown in four of these using the Shikata's orcein stain. An associated maternal HBsAg seropositivity was shown in two of the seropositive children. The youngest seropositive patient who developed PHC was 7 years old. The mother of this patient was also seropositive. These observations support a causal relation between childhood Hepatitis B virus infection and PHC. The importance of vertical or perinatal transmission of HBV in the causation of childhood PHC and the prophylactic role of childhood vaccination is emphasized. Attention is also drawn to the relative short malignant transformation time seen in some of these patients.
  11. Pavai S, Yap SF
    Med J Malaysia, 2003 Dec;58(5):667-72.
    PMID: 15190651
    The tumour marker CA19-9 is a sensitive marker for pancreatic, gastric and hepatobiliary malignancies. High CA 19-9 level indicates unresectable lesions and a poor prognosis. The objective of the study was to determine the significance and implications of elevated CA 19-9 levels in the serum. A one-year retrospective review of all patients who had CA19-9 measured in our Medical Centre was undertaken; 69 patients were found to have CA 19-9 level above the cut-off value (37 U/ml). Thirty-six patients had malignant and the remaining 33 had benign lesions. CA 19-9 was found to be elevated in malignancies of pancreas, colorectum, lung, liver and ovary. Benign conditions associated with elevation of CA 19-9 included disease of the hepatobiliary system, pneumonia, pleural effusion, renal failure and SLE. In two individuals, there was no obvious cause for the elevation of this marker. CA 19-9 levels were significantly lower in benign than in malignant conditions. In conclusion, elevated CA 19-9 may be found in patients with benign as well as malignant disease. Therefore, it is important (1) that elevated levels of CA 19-9 are interpreted in the light of the clinical presentation of the patient and (2) to be aware of the benign conditions that can be associated with increased levels of this marker. With these factors in mind, CA 19-9 can be used to assist in the diagnosis of pancreatic cancer and assessment of resection adequacy post-operatively.
  12. Cheah PL, Looi LM, Lin HP, Yap SF
    Pathology, 1991 Jan;23(1):66-8.
    PMID: 1648195
    A case of primary hepatocellular carcinoma (PHC) developing in a 10 year old boy who contracted Hepatitis B virus (HBV) infection in the course of maintenance phase chemotherapy for acute lymphoblastic leukemia was seen at University Hospital, Kuala Lumpur. This case is of interest in that it (1) supports an etiological relationship between HBV infection and PHC, (2) manifested a distinctly short malignant transformation time, and (3) draws attention to the possible contributory role of chemotherapy in increasing the risk of developing PHC.
  13. Chew WF, Masyita M, Leong PP, Boo NY, Zin T, Choo KB, et al.
    Singapore Med J, 2014 Feb;55(2):84-91.
    PMID: 24570317
    INTRODUCTION: Obesity is a major modifiable risk factor associated with most chronic diseases. The aim of this study was to determine the prevalence of obesity, and its associated risk factors, among apparently healthy Chinese adults in a Malaysian suburban village.

    METHODS: This was a cross-sectional study conducted among the Chinese residents in Seri Kembangan New Village, Klang Valley, Selangor, Malaysia. Convenience sampling was used for the selection of participants. Body weight, height, waist and hip circumferences, and blood pressure were measured. Fasting venous plasma was drawn for the measurement of fasting glucose level and lipid profile. Data on sociodemographic factors, dietary habits, physical activity, perceived stress level and sleep duration were collected using interviewer-administered, pretested and validated questionnaires.

    RESULTS: Among the 258 Chinese residents (mean age 41.4 ± 10.0 years) recruited, the prevalence of obesity was 40%. The obese participants had significantly higher mean blood pressure, and triglyceride and fasting plasma glucose levels than the non-obese participants (p < 0.05). The obese participants also had a significantly lower high-density lipoprotein cholesterol level than the non-obese participants. Logistic regression analysis showed that drinking soy milk (adjusted odds ratio [OR] 0.447; 95% confidence interval [CI] 0.253-0.787; p < 0.05) and the perception that a balanced diet consists mainly of vegetables (adjusted OR 0.440; 95% CI 0.215-0.900; p < 0.05) were associated with a reduced risk of obesity. The risk of obesity was higher in younger participants (adjusted OR 2.714; 95% CI 1.225-6.011; p < 0.05).

    CONCLUSION: The prevalence of obesity was high among the apparently healthy suburban Chinese. Our findings suggest that soy milk consumption and the perception that a balanced diet consists mainly of vegetables are associated with a lower risk of developing obesity in this population.
  14. Tan JA, George E, Tan KL, Chow T, Tan PC, Hassan J, et al.
    Clin Exp Med, 2004 Dec;4(3):142-7.
    PMID: 15599663 DOI: 10.1007/s10238-004-0048-x
    Beta-thalassemia is the most-common genetic disorder of hemoglobin synthesis in Malaysia, and about 4.5% of the population are heterozygous carriers of the disorder. Prenatal diagnosis was performed for 96 couples using the Amplification Refractory Mutation System and Gap-Polymerase Chain Reaction. We identified 17 beta-globin defects-initiation codon for translation (T-G), -29 (A-G), -28 (A-G), CAP +1 (A-C), CD 8/9 (+G), CD 15 (G-A), CD 17 (A-T), CD 19 (A-G), Hb E (G-A), IVS1-1 (G-T), IVS1-5 (G-C), CD 41/42 (-CTTT), CD 71-72 (+A), IVS2-654 (CT), poly A(A-G), 100-kb Ggamma(Agammadeltabeta) degrees and 45-kb Filipino deletions. The 192 beta-alleles studied comprised Chinese (151 patients), Malay (21), Orang Asli from East Malaysia (15), Filipino (1), Indian (1), Indonesian Chinese (2), and Thai (1). In the Chinese, 2 beta-globin defects at CD 41/42 and IVS2-654 were responsible for 74% of beta-thalassemia. beta-mutations at CD 19, IVS1-1 (G-T), IVS1-5, poly A, and hemoglobin E caused 76% of the hemoglobin disorders in the Malays. The Filipino 45-kb deletion caused 73.3% of bthalassemia in the Orang Asli. Using genomic sequencing, the rare Chinese beta-mutation at CD 43 (G-T) was confirmed in 2 Chinese, and the Mediterranean mutation IVS1-1 (G-A) was observed in a Malay beta-thalassemia carrier. The beta-globin mutations confirmed in this prenatal diagnosis study were heterogenous and 65 (68%) couples showed a different globin defect from each other. The use of specific molecular protocols has allowed rapid and successful prenatal diagnosis of beta-thalassemia in Malaysia.
  15. Pheh KS, Tan CS, Lee KW, Tay KW, Ong HT, Yap SF
    PLoS One, 2023;18(5):e0285435.
    PMID: 37167230 DOI: 10.1371/journal.pone.0285435
    Generalized anxiety disorder (GAD) is one of the most common mental disorders in Malaysia. Psychometrically sound measurements are urgently needed to assess anxiety symptoms. The extensively used Generalized Anxiety Disorder 7-item (GAD-7) is a promising candidate. However, studies on its factorial validity show mixed findings. While the one-factor solution has been replicated in different cultural contexts, some studies found different factorial structures instead. This study aimed to clarify the factorial validity of the English version of the GAD-7 in the Malaysian context. The responses collected from 1272 emerging to older adults in Malaysia were randomly divided into two halves and submitted to exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) respectively. Four acceptable models were explored in EFA ranging from unidimensional factor with 7 items to 3-factor models with 6 items. The four models revealed in EFA and the other competing models found in past studies were then examined and compared using CFA. The 6-item second-order model with a general factor of anxiety and three first-order factors with two items respectively (i.e., GAD-6) showed a more harmonic result and hence, is preferable. Moreover, the GAD-6 and its three subscales also showed satisfactory internal consistency and construct validity. This study uncovers a new and unique factorial structure of the GAD screening tool that fits in the Malaysian context. The scale may reveal GAD symptomatic dimensions that guide clinical interventions.
  16. Gan CY, Yap SF, Ngeow YF, Wong HC
    Sex Transm Dis, 1991 4 1;18(2):84-8.
    PMID: 1862464 DOI: 10.1097/00007435-199118020-00006
    This study documents the prevalence of Hepatitis B serological markers among STD patients who have had multiple sexual partners in Kuala Lumpur, Malaysia, and compares the rates with those of a sample of the population with single or no sexual partners. A total of 336 Chinese STD patients (multiple partners group) and 234 Chinese control subjects (non-multiple partner group) were screened. Those with a history of blood transfusion or parenteral drug abuse had been excluded from the study, and all study subjects were heterosexuals. The overall carrier rate was 9.2% for the multiple partner group (MP group) and 6.8% for the non-multiple partner group (NMP group). Infection rates were 64.3% for the MP-group and 38.9% for the NMP group. After adjustments for age and sex, there was no significant difference in carrier rates between the two groups, but infection rates were significantly different with the MP group, being 3.2 times more likely to acquire infection than the NMP group. The study concludes that in heterosexuals, those with multiple sexual partners have increased chances of acquiring HBV infection.
  17. Ong CS, Ngeow YF, Yap SF, Tay ST
    J Med Microbiol, 2010 Nov;59(Pt 11):1311-1316.
    PMID: 20688949 DOI: 10.1099/jmm.0.021139-0
    In this study, PCR-RFLP analysis (PRA) targeting hsp65 and rpoB gene regions was evaluated for the identification of mycobacterial species isolated from Malaysian patients. Overall, the hsp65 PRA identified 92.2 % of 90 isolates compared to 85.6 % by the rpoB PRA. With 47 rapidly growing species, the hsp65 PRA identified fewer (89.4 %) species than the rpoB PRA (95.7 %), but with 23 slow-growing species the reverse was true (91.3 % identification by the hsp65 PRA but only 52.5 % by the rpoB PRA). There were 16 isolates with discordant PRA results, which were resolved by 16S rRNA and hsp65 gene sequence analysis. The findings in this study suggest that the hsp65 PRA is more useful than the rpoB PRA for the identification of Mycobacterium species, particularly with the slow-growing members of the genus. In addition, this study reports 5 and 12 novel restriction patterns for inclusion in the hsp65 and rpoB PRA algorithms, respectively.
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