Displaying publications 1 - 20 of 78 in total

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  1. Chan M
    Br Med J, 1980 Feb 09;280(6211):401.
    PMID: 7362987
  2. Chan MF, Kwek E
    Malays Orthop J, 2020 Mar;14(1):81-83.
    PMID: 32296487 DOI: 10.5704/MOJ.2003.013
    Klebsiella pneumoniae is one of the leading causative organisms in pyogenic liver disease. It can cause disseminated infections, but rarely to bone, and rarely in healthy hosts. We report an unusual case of a distal humerus fracture from osteomyelitis secondary to dissemination in a non-immuno-compromised patient. The patient was surgically managed with external fixation and insertion of anti-biotic beads, in conjunction with medical therapy via culture direct antibiotics. This report highlights the diagnostic approach and treatment options for these atypical cases.
  3. Gan CY, Chan MK
    PMID: 8160073
    A survey was conducted to document the blood pressures of two indigenous groups (Kadazans and Bajaus) who reside in rural Sabah in East Malaysia. Their health knowledge status is also recorded. Fifty percent of those surveyed were unable to associate high blood pressure with a risk factor and as high as 38% were unaware of the consequences of high blood pressure. A total of 16.2% had blood pressures > or = 140/or 90mm Hg while 3.9% had blood pressures > or = 160/or 95mm Hg. While these figures are low compared to those of developed countries, lifestyle changes associated with rapid urbanization in Malaysia may be expected to increase hypertension prevalence. The strengthening of health education programs is timely as health knowledge is limited and many hypertensives default treatment.
  4. Chiu-Tsao ST, Chan M
    Biomed Imaging Interv J, 2009 Oct;5(4):e16.
    PMID: 21610987 DOI: 10.2349/biij.5.4.e16
    The authors have studied the feasibility of using three new high-sensitivity radiochromic devices in measuring the doses to peripheral points outside the primary megavoltage photon beams. The three devices were GAFCHROMIC® EBT film, prototype Low Dose (LD) Film, and prototype LD Card. The authors performed point dosimetry using these three devices in water-equivalent solid phantoms at x = 3,5,8,10, and 15 cm from the edge of 6 MV and 15 MV photon beams of 10x10 cm(2), and at depths of 0, 0.5 cm, and depth of maximum dose. A full sheet of EBT film was exposed with 5000 MU. The prototype LD film pieces were 1.5x2 cm(2) in size. Some LD films were provided in the form of a card in 1.8x5 cm(2) holding an active film in 1.8x2 cm(2). These are referred to as "LD dosimeter cards". The small LD films and cards were exposed with 500 MU. For each scanned film, a 6 mm circular area centered at the measurement point was sampled and the mean pixel value was obtained. The calibration curves were established from the calibration data for each combination of film/cards and densitometer/scanner. The doses at the peripheral points determined from the films were compared with those obtained using ion chamber at respective locations in a water phantom and general agreements were found. It is feasible to accurately measure peripheral doses of megavoltage photon beams using the new high-sensitivity radiochromic devices. This near real-time and inexpensive method can be applied in a clinical setting for dose measurements to critical organs and sensitive patient implant devices.
  5. Chan MY, Tay ST
    Mycoses, 2010 Jan;53(1):26-31.
    PMID: 19389064 DOI: 10.1111/j.1439-0507.2008.01654.x
    This study compared the enzymatic activity of clinical isolates of Cryptococcus neoformans, Cryptococcus gattii, environmental isolates of C. neoformans and non-neoformans Cryptococcus. Most of the cryptococcal isolates investigated in this study exhibited proteinase and phospholipase activities. Laccase activity was detected from all the C. neoformans and C. gattii isolates, but not from the non-neoformans Cryptococcus isolates. There was no significant difference in the proteinase, phospholipase and laccase activities of C. neoformans and C. gattii. However, significant difference in the enzymatic activities of beta-glucuronidase, alpha-glucosidase, beta-glucosidase and N-acetyl-beta-glucosaminidase between C. neoformans and C. gattii isolates was observed in this study. Environmental isolates of C. neoformans exhibited similar enzymatic profiles as the clinical isolates of C. neoformans, except for lower proteinase and laccase activities.
  6. Kan SK, Singh N, Chan MK
    Trans R Soc Trop Med Hyg, 1986;80(1):64-5.
    PMID: 3727000
    This is the first report in which a marine mollusc, Oliva vidua fulminans (olives), generally not known to be poisonous, was responsible for death in five children after consuming boiled olives with tamarind. The onset of symptoms was rapid 10 to 20 min after consumption of the olives. Signs and symptoms included nausea, vomiting, abdominal pain, tingling sensation around the lips, numbness around the mouth, drowsiness, lethargy and generalized weakness with paraesthesia in the limbs. The five deaths occurred within 3 to 4 hours after eating the poisoned olives and resulted from respiratory failure. Left-over olives from the affected household and freshly collected live olives had a toxicity of 14,200 mouse units (M.U.) and 15,000 M.U. per 100 g meat respectively. No other common chemical poison and organophosphorus insecticides were detected. The neurotoxic agent was acid and heat stable and was toxic at pH less than 4. Its action was similar to that of paralytic shellfish poisoning which was caused by toxins from certain dinoflagellates.
  7. Chan MK, Othman R, Zubir D, Salmijah S
    PMID: 11879780
    The relationship between a putative metallothionein gene (MT) and exposure to cadmium (Cd) in blood cockles (Anadara granosa) is reported. In a 96-h dose-response experiment, mortality of cockles was found to proportionately increase in the range of 0.2-5.0 mg/l Cd with a calculated LC(50) of 2.94 mg/l. Exposure to 0.25 mg/l Cd for 16 days caused significant increases (P<0.05) in Cd concentrations in whole tissues, gills and hepatopancreas, and the accumulation of Cd in these tissues increased with the duration of exposure. Two cDNA libraries constructed using the hepatopancreas from control and Cd-treated cockles gave titres of 5.62 x 10(5) and 1.94 x 10(5) pfu/microg vector, respectively. A putative MT gene, AnaMT, of 510 nucleotides in length, was isolated from the treated cDNA library using a heterologous probe MT20 from the blue mussel, Mytilus edulis. Northern analyses using AnaMT as a probe indicated low expression of the MT mRNA in control animals. In cockles treated with 0.25 mg/l Cd for 4 days, MT mRNA level increased to approximately 168%, but declined to 108% at day 8. After 12 and 16 days of Cd treatment, expression of the MT gene was 138% and 187%, respectively, compared to the controls. These observations suggest that induction of the MT gene by a sublethal dose of Cd is rapid, occurring within 4 days of treatment.
  8. Chan M, Yang J, Song Y, Burman C, Chan P, Li S
    Biomed Imaging Interv J, 2011 Apr;7(2):e11.
    PMID: 22287985 DOI: 10.2349/biij.7.2.e11
    PURPOSE: The imaging characteristics of two popular kV cone-beam CT (CBCT) and two MVCT systems utilised in image-guided radiation therapy (IGRT) were evaluated.

    MATERIALS AND METHODS: The study was performed on Varian Clinac iX, Elekta Synergy S, Siemens Oncor, and Tomotherapy. A CT phantom (Catphan-504, Phantom Laboratory, Salem, NY) was scanned for measurements of image quality including image noise, uniformity, density accuracy, spatial resolution, contrast linearity, and contrast resolution. The measurement results were analysed using in-house image analysis software. Reproducibility, position correction, and geometric accuracy were also evaluated with markers in a smaller alignment phantom. The performance evaluation compared volumetric image properties from these four systems with those from a conventional diagnostic CT (CCT).

    RESULTS: It was shown that the linearity of the two kV CBCT was fairly consistent with CCT. The Elekta CBCT with half-circle 27-cm FOV had higher CT numbers than the other three systems. The image noises of the Elekta kV CBCT, Siemens MV CBCT, and Tomotherapy fan-beam CT (FBCT) are about 2-4 times higher than that of the Varian CBCT. The spatial resolutions of two kV CBCTs and two MV CBCTs were 8-11 lp/cm and 3-5 lp/cm, respectively.

    CONCLUSION: Elekta CBCT provided a faster image reconstruction and low dose per scan for half-circle scanning. Varian CBCT had relatively lower image noise. Tomotherapy FBCT had the best uniformity.

  9. Yap YY, Hassan S, Chan M, Choo PK, Ravichandran M
    Otolaryngol Head Neck Surg, 2007 Jun;136(6):986-91.
    PMID: 17547993
    OBJECTIVES: This study examines the presence of Epstein-Barr virus (EBV) in nasopharyngeal carcinoma (NPC) by using polymerase chain reaction (PCR).

    STUDY DESIGN: Eighty-six postnasal biopsy samples and 71 fine-needle aspirate samples of neck masses were obtained from patients who were clinically suspect for NPC. Genomic DNA was extracted from the samples, and EBNA1, EBNA2, and LMP genes of EBV were detected by PCR. PCR results were compared with NPC histopathology findings.

    RESULTS: The sensitivity of PCR to detect EBNA1 (97.14%), EBNA2 (88.57%), and LMP (91.43%) genes of EBV in nasopharyngeal biopsy samples were higher than those in fine-needle aspirate samples.

    CONCLUSION: Detection of EBV by PCR in tissue obtained from nasopharyngeal biopsy and fine-needle aspirate samples of neck masses is a relatively inexpensive, reliable, and accurate method of diagnosing NPC. Detection of EBV genes is on par with histopathological examination (HPE) and superior to fine-needle aspirate cytology.

    SIGNIFICANCE: PCR is an ideal tool for suggesting NPC and guiding the diagnostic workup in occult primary tumors, facilitating earlier diagnosis and reducing morbidity and mortality.

  10. Gan CY, Chin B, Teoh ST, Chan MK
    PMID: 8266232
    The nutritional status of 896 Kadazan children below 6 years of age from 23 villages of Tambunan District were studied. When stunting and wasting were defined as those who were below two standard deviations of height-for-age and weight-for-height (Waterlow et al, 1977) and based on the National Center for Health Statistics reference population, 67.6% of boys and 66.8% of girls were stunted while 12.3% of boys and 8.3% of girls were wasted. Weaning foods and toddler feeding practices were unsatisfactory. The role of health education on child care and feeding practices is emphasized.
  11. Hii J, Kan S, Pereira M, Parmar SS, Campos RL, Chan MK
    Trop Geogr Med, 1985 Jun;37(2):93-101.
    PMID: 3898498
    An epidemiological survey of filariasis and malaria in Banggi Island and Upper Kinabatangan, Sabah, revealed microfilarial rates of 7.2% and 8.6% respectively and malaria prevalence of 9.7% and 16.9% respectively. Wuchereria bancrofti was a rural nocturnally periodic type with a periodicity index of 137.2 and average peak hour at 01.32 hrs; 9.2% of microfilaremic carriers as compared to 2.4% amicrofilaremic subjects had clinical filariasis. The Plasmodium falciparum: P. vivax: P. malariae ratios were 1:1:0.17 and 1.4:1:0.12 for Banggi and Upper Kinabatangan respectively. Anopheles flavirostris was incriminated as a new malaria vector in Banggi where the well-known primary malaria vector is An. balabacensis. The latter was also found for the first time to be a vector of rural W. bancrofti in Upper Kinabatangan. Experimental feeding also showed that L3 larvae of W. bancrofti were recovered at low rates from An. balabacensis. Aedes togoi appeared to be a suitable laboratory vector for W. bancrofti.
  12. Lim WS, Cheah WK, Ali N, Han HC, Anthony PV, Chan M, et al.
    Int Psychogeriatr, 2014 Apr;26(4):677-86.
    PMID: 24382159 DOI: 10.1017/S1041610213002445
    Recent studies that describe the multidimensionality of the Zarit Burden Interview (ZBI) challenge the traditional dual-factor paradigm of personal and role strains (Whitlatch et al., 1991). These studies consistently reported a distinct dimension of worry about caregiver performance (WaP) comprising items 20 and 21.The present study aims to compare WaP against conventional ZBI domains in a predominantly Chinese multi-ethnic Asian population.
  13. Chan M, Cheong TG, Kurunathan S, Chandrika M, Ledon T, Fando R, et al.
    Microb Pathog, 2010 Nov;49(5):211-6.
    PMID: 20558271 DOI: 10.1016/j.micpath.2010.06.001
    Cholera caused by the O139 serogroup still remains a public health concern in certain regions of the world and the existing O1 vaccines do not cross-protect cholera caused by this serogroup. An aminolevulinic acid (ALA) auxotroph vaccine candidate against the O139 serogroup, designated as VCUSM2, was recently developed. It was found to be immunogenic in animal model studies but showed mild reactogenic effects due to the presence of two intact copies of Vibrio cholerae toxin (CTX) genetic element. In the present study we have modified the ctx operon by systematic allelic replacement methodology to produce a mutant strain, designated as VCUSM14. This strain has two copies of chromosomally integrated and mutated ctxA gene, encoding immunogenic but not toxic cholera toxin A subunit (CT-A). The amino acids arginine and glutamic acid at position 7th and 112th, respectively, in CT-A of VCUSM14 were substituted with lysine (R7K) and glutamine (E112Q), respectively. Two copies of the ace and zot genes present in the ctx operon were also deleted. Cholera toxin-ELISA using GM1 ganglioside showed that the both wild type CT and mutated CT were recognized by anti-CT polyclonal antibodies. VCUSM14 produced comparatively less amount of antigenic cholera toxin when compared to the VCUSM2 and Bengal wild type strain. VCUSM14 did not elicit fluid accumulation when inoculated into rabbit ileal loops at doses of 10(6) and 10(8) CFU. The colonization efficiency of VCUSM14 was one log lower than the parent strain, VCUSM2, which can be attributed to the ALA auxotrophy and less invasive properties of VCUSM14. VCUSM14, thus a non-reactogenic auxotrophic vaccine candidate against infection by O139 V. cholerae.
  14. Cheong TG, Chan M, Kurunathan S, Ali SA, ZiNing T, Zainuddin ZF, et al.
    Microb Pathog, 2010 Feb;48(2):85-90.
    PMID: 19900531 DOI: 10.1016/j.micpath.2009.11.001
    Vibrio cholerae is a Gram-negative bacterium that causes diarrheal disease. V. cholerae O1 and O139 serogroups are toxigenic and are known to cause epidemic cholera. These serogroups produce cholera toxin and other accessory toxins such as accessory cholera enterotoxin, zonula occludens toxin, and multifunctional, autoprocessing repeat in toxin (MARTX). In the present study, we incorporated mutated rtxA and rtxC genes that encode MARTX toxin into the existing aminolevulinic acid (ALA) auxotrophic vaccine candidate VCUSM2 of V. cholerae O139 serogroup. The rtxC mutant was named VCUSM9 and the rtxC/rtxA mutant was named VCUSM10. VCUSM9 and VCUSM10 were able to colonize intestinal cells well, compared with the parent vaccine strain, and produced no fluid accumulation in a rabbit ileal loop model. Cell rounding and western blotting assays indicated that mutation of the rtxC gene alone (VCUSM9 strain) did not abolish MARTX toxicity. However mutation of both the rtxA and rtxC genes (VCUSM10) completely abolished MARTX toxicity. Thus we have produced a new, less reactogenic, auxotrophic rtxC/rtxA mutated vaccine candidate against O139 V. cholerae.
  15. Ahmad NS, Chan MY, Hiew FL, Sharif SA, Vijayasingham P, Thayaparan T, et al.
    Med J Malaysia, 2003 Oct;58(4):526-32.
    PMID: 15190628
    The cornerstone of asthma management is achieving adequate symptom control and patient education. We studied in our local population of asthmatic patients how well their symptoms were controlled with currently prescribed treatment and their insight into the disease and its management. Over a 6-month period, 93 asthmatics recruited from two local government health clinics and a state hospital were interviewed using a standard questionnaire. Patients were classified into 4 groups based on the treatment they were on according to Global Initiative for Asthma (GINA) treatment guidelines. The number of patients in Step 1 (rescue medication alone), Step 2 (1 controller medication), Step 3 (2 controller medications) and Step 4 (at least 3 controller medications) were 8, 39, 34 and 12, respectively. Except for day symptoms in Step 1 group, fewer than 50% achieved minimum day or night symptoms and no restriction of daily activities. Questions on patient insight were only available for 50 patients. Weather change (74%), air pollution (66%) and physical stress (46%) were the three highest ranked common asthma triggers. More than half correctly recognized the important symptoms of a serious asthma attack but fewer than 15% were familiar with the peak flow meter and its use or with the asthma self-management plan. Most patients perceived that their treatment had helped reduce disease severity and exacerbations. We conclude that symptom control and some aspect of patient education are still lacking in our local asthmatics.
    Study site: Hospital Tuanku Jaafar, Seremban, Negeri Sembilan; Klinik Kesihatan Seremban; Klinik Kesihatan Ampangan, Malaysia
  16. Kopple JD, Karupaiah T, Chan M, Burrowes JD, Kirk J, Prest M
    J Ren Nutr, 2021 Mar 31.
    PMID: 33812799 DOI: 10.1053/j.jrn.2021.02.005
  17. Tan KY, van der Beek EM, Chan MY, Zhao X, Stevenson L
    Nutr Rev, 2015 Sep;73(9):634-41.
    PMID: 26269489 DOI: 10.1093/nutrit/nuv029
    The Association of Southeast Asian Nations aims to act as a single market and allow free movement of goods, services, and manpower. The purpose of this article is to present an overview of the current regulatory framework for health claims in Southeast Asia and to highlight the current barriers and opportunities in the regulatory frameworks in the Association of Southeast Asian Nations. To date, 5 countries in Southeast Asia, i.e., Indonesia, Malaysia, the Philippines, Singapore, and Thailand, have regulations and guidelines to permit the use of health claims on food products. There are inconsistencies in the regulations and the types of evidence required for health claim applications in these countries. A clear understanding of the regulatory frameworks in these countries may help to increase trade in this fast-growing region and to provide direction for the food industry and the regulatory community to develop and market food products with better nutritional quality tailored to the needs of Southeast Asian consumers.
  18. Lim KK, Chan M, Navarra S, Haq SA, Lau CS
    Best Pract Res Clin Rheumatol, 2016 06;30(3):398-419.
    PMID: 27886939 DOI: 10.1016/j.berh.2016.08.007
    This chapter discusses the challenges faced in the development and implementation of musculoskeletal (MSK) Models of Care (MoCs) in middle-income and low-income countries in Asia and outlines the components of an effective MoC for MSK conditions. Case studies of four such countries (The Philippines, Malaysia, Bangladesh and Myanmar) are presented, and their unique implementation issues are discussed. The success experienced in one high-income country (Singapore) is also described as a comparison. The Community Oriented Program for Control of Rheumatic Diseases (COPCORD) project and the role of Asia Pacific League of Associations for Rheumatology (APLAR), a professional body supporting MoC initiatives in this region, are also discussed. The experience and lessons learned from these case studies can provide useful information to guide the implementation of future MSK MoC initiatives in other middle-income and low-income countries.
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