Displaying all 17 publications

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  1. Spectrum and management of dentofacial deformities in a multiethnic Asian population
    Chew MT
    Angle Orthod, 2006 Sep;76(5):806-9.
    PMID: 17029514
    The aim of this retrospective study is to investigate the spectrum and management of dentofacial deformities in a multiethnic Asian community.
  2. Fine needle aspiration cytology of lymph nodes in HIV-infected individuals
    Jayaram G, Chew MT
    Acta Cytol., 2000 Nov-Dec;44(6):960-6.
    PMID: 11127753
    OBJECTIVE: To assess the role of fine needle aspiration cytology (FNAC) in lymphadenopathy in human immunodeficiency virus-infected individuals (HIVII).

    STUDY DESIGN: Thirty-nine HIVII presenting with lymphadenopathy at University Hospital, Kuala Lumpur, were subjected to FNAC. Cytologic smears were routinely stained with May-Grünwald-Giemsa stain. Special stains and immunostains were used when necessary.

    RESULTS: In nine cases, the cytologic appearance was compatible with HIV type A and in one case with HIV type C lymphadenopathy. In 21 cases, acid-fast bacilli (AFB) were demonstrated in the cytologic smears, enabling a diagnosis of mycobacterial lymphadenitis. In one of these cases there was a concomitant infection with Penicillium marneffei that was overlooked on initial cytologic examination. The cause of granulomatous lymphadenitis could not be ascertained in one case, where neither AFB nor any other organisms were demonstrable. Two cases of histoplasma and one of cryptococcal lymphadenitis were diagnosed, as was one high grade non-Hodgkin's lymphoma that could be immunophenotyped on cytologic material. In three cases the aspirates were inadequate for a cytologic diagnosis.

    CONCLUSION: Lymph node FNAC is a valuable investigative modality in HIVII. Most opportunistic infections (bacterial and fungal) can be correctly identified, and high grade lymphoma can be diagnosed and phenotyped.
  3. An Asian community's perspective on facial profile attractiveness
    Soh J, Chew MT, Wong HB
    Community Dent Oral Epidemiol, 2007 Feb;35(1):18-24.
    PMID: 17244134
    To assess the facial profile preferences of laypersons in an Asian community and the influence of age, ethnic and gender on profile selection.
  4. Cytologic appearances in invasive lobular carcinoma of the breast. A study of 21 cases
    Jayaram G, Swain M, Chew MT, Yip CH
    Acta Cytol., 2000 Mar-Apr;44(2):169-74.
    PMID: 10740602
    OBJECTIVE: To examine the fine needle aspiration cytologic features of invasive lobular carcinoma of breast and to discuss problems that may occur in cytodiagnosis.

    STUDY DESIGN: Fine needle aspiration cytologic smears from 21 cases of invasive lobular carcinoma (ILC) of breast were subjected to detailed cytomorphologic analysis. Features studied included pattern of cells, size of cells, nuclear placement, pleomorphism, presence of intracytoplasmic lumina (ICL) and signet ring cells.

    RESULTS: Cellularity was generally moderate or high, and the pattern was predominantly or partly dissociated in 86% of cases. Rosettelike pattern was discerned in alveolar-type ILC. Cell size was usually small or intermediate, with nuclei placed eccentrically in most cases. ICLs with or without signet ring cells were present in 12 cases (57%).

    CONCLUSION: A cytologic picture consisting of predominantly dissociated small or intermediate-sized tumor cells with eccentric nuclei, with some of the cells showing ICLs, is highly suggestive of ILC. Indian file pattern, another characteristic feature of ILC, is, however, focal and inconsistent. Variant patterns of ILC may show other cytologic features, such as rosettelike pattern (alveolar variant of ILC) or large cell pattern (pleomorphic variant of ILC) and may consequently be difficult to categorize on cytologic smears.
  5. Cytology of mucinous carcinoma of breast: a report of 28 cases with histological correlation
    Jayaram G, Swain M, Chew MT, Yip CH, Moosa F
    Malays J Pathol, 2000 Dec;22(2):65-71.
    PMID: 16329537
    Pure mucinous carcinoma (MC) of the breast is a relatively uncommon variant of breast carcinoma with distinctive histological and cytological features. In this study we have analysed fine needle aspiration (FNA) cytological material from 28 cases of MC of breast and correlated the cytomorphological features with histopathology. The 28 patients consisted of 27 females and one male patient. 14 patients were Chinese, 10 were Indian and four were Malay. Their ages ranged from 38 to 90 with a mean at 52 years. The left breast was involved in 17 and the right in 11 cases. The duration of the lump varied from two weeks to 10 years. The cytological picture was characterized by abundant extracellular mucin giving a "sea of mucin" or "whirlpools of mucin" effect, in which were seen floating clusters of tumour cells with relatively bland cytological features. Myxo-vascular fragments were seen in 12 cases. Dissociated tumour cells showed a plasmacytoid appearance with eccentric nuclei. In four cases, the mucin was scanty in amount and the cellularity was high while in two cases, the cellularity was very low. Psammoma bodies were seen in cytological smears in one case. Histological study of excision or mastectomy specimens confirmed all 28 cases to be pure MC. Knowledge of the distinctive cytomorphological appearance of MC would enable correct identification of these lesions as malignant and prompt treatment that could further enhance the survival of these prognostically good breast cancers.
  6. 68Ga-PSMA PET/CT and 18F-FDG PET/CT in Renal Cell Carcinoma
    Chen EJ, Tan TH, Chew MT, Chye PC
    Clin Nucl Med, 2020 Jul;45(7):e317-e319.
    PMID: 32404702 DOI: 10.1097/RLU.0000000000003053
    Recent case reports and series have demonstrated the usefulness of Ga/F-PSMA PET/CT in restaging recurrent renal cancer after nephrectomy. We presented a case of a patient with renal mass who had undergone both F-FDG and Ga-PSMA PET/CT for diagnosis and staging. Concordant tracer uptake in the primary tumor and metastatic lesions was demonstrated by both radiotracers. Final histopathological reports revealed clear cell renal cell carcinoma. Furthermore, unusual left metacarpal bone metastasis was also detected.
  7. Fulltext Colon Carcinogenesis: The Interplay Between Diet and Gut Microbiota
    Loke YL, Chew MT, Ngeow YF, Lim WWD, Peh SC
    Front Cell Infect Microbiol, 2020;10:603086.
    PMID: 33364203 DOI: 10.3389/fcimb.2020.603086
    Colorectal cancer (CRC) incidence increases yearly, and is three to four times higher in developed countries compared to developing countries. The well-known risk factors have been attributed to low physical activity, overweight, obesity, dietary consumption including excessive consumption of red processed meats, alcohol, and low dietary fiber content. There is growing evidence of the interplay between diet and gut microbiota in CRC carcinogenesis. Although there appears to be a direct causal role for gut microbes in the development of CRC in some animal models, the link between diet, gut microbes, and colonic carcinogenesis has been established largely as an association rather than as a cause-and-effect relationship. This is especially true for human studies. As essential dietary factors influence CRC risk, the role of proteins, carbohydrates, fat, and their end products are considered as part of the interplay between diet and gut microbiota. The underlying molecular mechanisms of colon carcinogenesis mediated by gut microbiota are also discussed. Human biological responses such as inflammation, oxidative stress, deoxyribonucleic acid (DNA) damage can all influence dysbiosis and consequently CRC carcinogenesis. Dysbiosis could add to CRC risk by shifting the effect of dietary components toward promoting a colonic neoplasm together with interacting with gut microbiota. It follows that dietary intervention and gut microbiota modulation may play a vital role in reducing CRC risk.
  8. Extended Whole-body Ga-68 DOTATATE PET-CT in evaluating Tumour-Induced Osteomalacia: Case report and review of literature
    Tan TH, Chen EJ, Chew MT, Chye PC, Wong M
    Nucl Med Mol Imaging, 2021 Jun;55(3):130-135.
    PMID: 34109008 DOI: 10.1007/s13139-021-00695-6
    Tumour-induced osteomalacia is a rare paraneoplastic syndrome that manifests as chronic hypophosphataemia, non-specific bone pain and muscle weakness. It is generally caused by phosphaturic mesenchymal tumour (PMT), which is uncommonly associated with synchronous tumours. However, diagnosis is often delayed for several years due to the rarity, indolent growing nature and non-specific symptoms of the disease, often resulting in an overlook by clinicians during assessments. The patient initially presented with hypophosphataemia and generalised skeletal pain with multiple atraumatic fractures. Blood tests revealed serum calcium levels at the upper limit and extremely low inorganic phosphate levels. Herein, we report a case where two synchronous PMTs from two different sites were detected by 'extended' whole-body Ga-68 DOTATATE PET-CT, leading to remission of the disease after complete surgical removal. Early detection and diagnosis of PMT neoplasm is crucial, as complete surgical resection of this tumour is the only definitive treatment currently known. Upon excision, this curable disease will result in complete resolution of symptoms and blood parameters, leading to remission of the disease which significantly improves the patient's quality of life. PMT often over-expresses somatostatin receptors (SSTR), predominantly subtype 2A, and Ga-68 DOTATATE PET-CT is a selective SSTR imaging that targets this characteristic over-expression in these tumours. The high diagnostic accuracy of Ga-68 DOTATATE PET-CT should be the primary imaging modality for full evaluation of this disease.
  9. Fulltext The radiobiological effects of He, C and Ne ions as a function of LET on various glioblastoma cell lines
    Chew MT, Bradley DA, Suzuki M, Matsufuji N, Murakami T, Jones B, et al.
    J Radiat Res, 2019 Mar 01;60(2):178-188.
    PMID: 30624699 DOI: 10.1093/jrr/rry099
    The effects of the charged ion species 4He, 12C and 20Ne on glioblastoma multiforme (GBM) T98G, U87 and LN18 cell lines were compared with the effects of 200 kVp X-rays (1.7 keV/μm). These cell lines have different genetic profiles. Individual GBM relative biological effectiveness (RBE) was estimated in two ways: the RBE10 at 10% survival fraction and the RBE2Gy after 2 Gy doses. The linear quadratic model radiosensitivity parameters α and β and the α/β ratio of each ion type were determined as a function of LET. Mono-energetic 4He, 12C and 20Ne ions were generated by the Heavy Ion Medical Accelerator at the National Institute of Radiological Sciences in Chiba, Japan. Colony-formation assays were used to evaluate the survival fractions. The LET of the various ions used ranged from 2.3 to 100 keV/μm (covering the depth-dose plateau region to clinically relevant LET at the Bragg peak). For U87 and LN18, the RBE10 increased with LET and peaked at 85 keV/μm, whereas T98G peaked at 100 keV/μm. All three GBM α parameters peaked at 100 keV/μm. There is a statistically significant difference between the three GBM RBE10 values, except at 100 keV/μm (P < 0.01), and a statistically significant difference between the α values of the GBM cell lines, except at 85 and 100 keV/μm. The biological response varied depending on the GBM cell lines and on the ions used.
  10. Fulltext Potential lethal damage repair in glioblastoma cells irradiated with ion beams of various types and levels of linear energy transfer
    Chew MT, Nisbet A, Suzuki M, Matsufuji N, Murakami T, Jones B, et al.
    J Radiat Res, 2019 Jan 01;60(1):59-68.
    PMID: 30452663 DOI: 10.1093/jrr/rry081
    Glioblastoma (GBM), a Grade IV brain tumour, is a well-known radioresistant cancer. To investigate one of the causes of radioresistance, we studied the capacity for potential lethal damage repair (PLDR) of three altered strains of GBM: T98G, U87 and LN18, irradiated with various ions and various levels of linear energy transfer (LET). The GBM cells were exposed to 12C and 28Si ion beams with LETs of 55, 100 and 200 keV/μm, and with X-ray beams of 1.7 keV/μm. Mono-energetic 12C ions and 28Si ions were generated by the Heavy Ion Medical Accelerator at the National Institute of Radiological Science, Chiba, Japan. Clonogenic assays were used to determine cell inactivation. The ability of the cells to repair potential lethal damage was demonstrated by allowing one identical set of irradiated cells to repair for 24 h before subplating. The results show there is definite PLDR with X-rays, some evidence of PLDR at 55 keV/μm, and minimal PLDR at 100 keV/μm. There is no observable PLDR at 200 keV/μm. This is the first study, to the authors' knowledge, demonstrating the capability of GBM cells to repair potential lethal damage following charged ion irradiations. It is concluded that a GBM's PLDR is dependent on LET, dose and GBM strain; and the more radioresistant the cell strain, the greater the PLDR.
  11. Fulltext Low radiation dose to treat pneumonia and other inflammations
    Chew MT, Daar E, Khandaker MU, Jones B, Nisbet A, Bradley DA
    Br J Radiol, 2021 Aug 01;94(1124):20201265.
    PMID: 34192471 DOI: 10.1259/bjr.20201265
    Infection, the invasion of pathogenic microorganisms and viruses, causes reactive inflammation mediated by endogenous signals, with influx of leucocytes with distinct properties and capable of mounting a cellular or antibody response. Different forms of inflammation may also occur in response to tumours, in allergy and autoimmune disorders. Pneumonia, respiratory tract infection and septic shock for instance can arise as serious complications of the Covid-19 virus. While radiotherapy has been most widely used to control malignant tumours, it has also been used for treatment of non-malignant diseases, including acute and chronic inflammation in situations where anti-inflammatory drugs may be ineffective or contraindicated. The present review examines the history and prospects for low-dose anti-inflammatory radiation treatments, the present interest largely being motivated by the increased incidence of pulmonary disease associated Covid-19 infections. Evidence in support of the suggested efficacy are covered, together with an appraisal of one of the number of potential convenient sources that could complement external beam arrangements.
  12. Bibliometric Review of Optimization and Image Processing of Positron Emission Tomography (PET) Imaging System between 1981-2022
    Murat H, Awang Kechik MM, Chew MT, Kamal I, Abdul Karim MK
    Curr Med Imaging, 2024 Apr 09.
    PMID: 38616750 DOI: 10.2174/0115734056282004240403042345
    BACKGROUND: PET scan stands as a valuable diagnostic tool in nuclear medicine, enabling the observation of metabolic and physiological changes at a molecular level. However, PET scans have a number of drawbacks, such as poor spatial resolution, noisy images, scattered radiation, artifacts, and radiation exposure. These challenges demonstrate the need for optimization in image processing techniques.

    OBJECTIVES: Our objective is to identify the evolving trends and impacts of publication in this field, as well as the most productive and influential countries, institutions, authors, themes, and articles.

    METHODS: A bibliometric study was conducted using a comprehensive query string such as "positron emission tomography" AND "image processing" AND optimization to retrieve 1,783 publications from 1981 to 2022 found in the Scopus database related to this field of study.

    RESULTS: The findings revealed that the most influential country, institution, and authors are from the USA, and the most prevalent theme is TOF PET image reconstruction.

    CONCLUSION: The increasing trend in publication in the field of optimization of image processing in PET scans would address the challenges in PET scan by reducing radiation exposure, faster scanning speed, as well as enhancing lesion identification.

  13. Fulltext Measurement accuracy and reliability of self-reported versus measured weight and height among adults in Malaysia: Findings from a nationwide blood pressure screening programme
    Chia YC, Ching SM, Ooi PB, Beh HC, Chew MT, Chung FFL, et al.
    PLoS One, 2023;18(1):e0280483.
    PMID: 36649290 DOI: 10.1371/journal.pone.0280483
    Most studies reporting prevalence of obesity use actual weight and height measurements. Self-reported weight and height have been used in epidemiological studies as they have been shown to be reliable, convenient, and inexpensive alternatives to actual measurements. However, the accuracy of self-reported weight and height might vary in different regions because of the difference in health awareness and social influences. This study aims to determine the accuracy and reliability of self-reported weight and height compared to actual measured weight and height among adults in Malaysia. This was a cross-sectional study conducted at the community level during blood pressure screening campaigns. Participants self-reported their weight and height in a questionnaire survey. Their weight and height were validated using measurements by researchers on the same setting. Body mass index (BMI) was defined as underweight (<18.5kg/m2), normal (18.5-22.9 kg/m2), overweight (23-27.4 kg/m2) and obesity (≥27.5 kg/m2). Bland-Altman analysis, intraclass correlation coefficients and weighted Kappa statistics were used to assess the degree of agreement between self-reported and measured weight and height. A total of 2781 participants were recruited in this study. The difference between the mean self-reported and measured weight and height were 0.4 kg and 0.4 cm respectively. Weighted Kappa statistics analysis showed that there was a substantial agreement between the BMI classifications derived from self-reported and actual measurement (ҡ = 0.920, p<0.001). There was no marked difference in the sensitivity and specificity of self-reported BMI among Malaysian adults by gender. We observed substantial agreement between self-reported and measured body weight and height within a sample of Malaysian adults. While self-reported body weight showed weaker agreement with actual measurements particularly for obese and overweight individuals, BMI values derived from self-reported weight and height were accurate for 88.53% of the participants. We thus conclude that self-reported height and weight measures may be useful for tracking and estimating population trends amongst Malaysian adults.
  14. Low dose and low dose rate radioluminescence dosimetry
    Bradley DA, Essa RZ, Peh SC, Teow SY, Chew MT, Zubair HT, et al.
    Appl Radiat Isot, 2023 Aug;198:110875.
    PMID: 37257265 DOI: 10.1016/j.apradiso.2023.110875
    Review is provided of a number of low-dose, low dose rate situations that in study require advances in the development of dosimetric facilities. Using a clinical linac set up to provide doses down to the few mGy level, the performance of a real-time radioluminescence system has then been illustrated, accommodating pulsed as well as continuous dose delivery. The system gate times provide for tracking of the pattern of dose delivery, allowing detailed account of dose and dose-rate variations. The system has been tested in both x-ray and electron mode dose delivery.
  15. Ethnic differences in knowledge, attitudes, and practices related to dietary salt intake and association with hypertension in Malaysia: a multi-centre cross-sectional study
    Chia YC, Ching SM, Chew MT, Devaraj NK, Oui JEK, Lim HM, et al.
    Hypertens Res, 2024 Sep 02.
    PMID: 39223391 DOI: 10.1038/s41440-024-01851-z
    The association between high salt intake and elevated blood pressure levels has been well-documented. However, studies on how effectively this knowledge translates into actionable practices, particularly across different ethnic groups, remain limited. This study aimed to evaluate the knowledge, attitudes, and practices (KAP) towards dietary salt intake across ethnicities and determine its association with hypertension. 5128 Malaysian adults recruited from a national blood pressure screening study completed questionnaires on demographics, and KAP related to dietary salt intake. There were 57.4% Malay, 23.5% Chinese, 10.4% Indian, and 8.7% individuals of other ethnic groups. Overall, more than 90% of the participants knew that a high salt intake causes serious health problems, but only around one-third knew the relationship between high salt intake and strokes and heart failure. Participants of different ethnic groups displayed significant differences in the KAP domains, where Indians generally exhibited better knowledge, attitudes, and reported better practices such as reading salt labels and using spices. Those who were unaware of the difference between salt and sodium and who reported not reading salt labels had higher odds of having elevated blood pressure. These findings demonstrate that while there is a suboptimal translation of salt knowledge into practice in Malaysia, with significant differences in KAP observed between ethnic groups, the potential of improving health outcomes by improving the clarity and awareness of salt labels is substantial. Tailored education promoting salt-label reading, minimizing processed foods intake and discretionary salt use should be ethnic-specific to better curb this escalating hypertension epidemic.
  16. Fulltext May Measurement Month 2019: an analysis of blood pressure screening results from Malaysia
    Chia YC, Devaraj NK, Chook JB, Chew MT, Ooi PB, Mohamed M, et al.
    Eur Heart J Suppl, 2021 May;23(Suppl B):B98-B100.
    PMID: 34054370 DOI: 10.1093/eurheartj/suab058
    Despite hypertension remaining the leading cause of death worldwide, awareness of hypertension and its control rate is still suboptimal in Malaysia. This study aims to determine the proportion of both diagnosed and undiagnosed hypertension, awareness and its control rate during the yearly May Measurement Month (MMM) campaign that has been coordinated by the International Society of Hypertension. Participants aged ≥18 years were recruited at various screening sites namely universities, health facilities, shopping malls, and other sites. Participant's socio-demographic, environmental, and lifestyle data were captured using a questionnaire. Three blood pressure (BP) readings as well as anthropometric measurements were obtained from all participants. The mean of the second and third BP readings was used in analyses. Hypertension was defined as a systolic BP ≥140 mmHg and/or diastolic BP ≥90 mmHg or taking antihypertensive medication. A total of 3062 participants were recruited. The proportion with hypertension in our study was 18.7% (n = 572). The proportion who were aware of their BP status was 63.2%. More than half (57.2%) of the hypertensives were on antihypertensive medication and 70.3% of those treated were controlled. In conclusion, in this BP screening campaign, one in five were hypertensive with almost two thirds aware of their hypertensive status. BP control among those who are taking medications was high at 70% but under 60% of hypertensives were on treatment. Hypertension screening programmes are important to promote awareness and control of hypertension as well as to reduce the devastating complications associated with this disorder.
  17. Fulltext Relationship of an adherence score with blood pressure control status among patients with hypertension and their determinants: Findings from a nationwide blood pressure screening program
    Chia YC, Devaraj NK, Ching SM, Ooi PB, Chew MT, Chew BN, et al.
    J Clin Hypertens (Greenwich), 2021 03;23(3):638-645.
    PMID: 33586334 DOI: 10.1111/jch.14212
    This study aimed to examine the relationship of adherence with blood pressure (BP) control and its associated factors in hypertensive patients. This cross-sectional nationwide BP screening study was conducted in Malaysia from May to October 2018. Participants with self-declared hypertension completed the Hill-Bone Compliance to High Blood Pressure Therapy Scale (Hill-Bone CHBPTS) which assesses three important domains of patient behavior to hypertension management namely medication taking, appointment keeping and reduced salt intake. Lower scores indicate better compliance while higher scores indicate otherwise. Participant's body mass index and seated BP were measured based on standard measurement protocol. Determinants of adherence to treatment were analyzed using multiple linear regression. Out of 5167 screened subjects, 1705 were known hypertensives. Of these, 927 (54.4%) answered the Hill-Bone CHBPTS and were entered into analysis. The mean age was 59.0 ± 13.2 years, 55.6% were female and 42.2% were Malays. The mean Hill-Bone CHBPTS score was 20.4 ± 4.4 (range 14-47), and 52.1% had good adherence. The mean systolic BP and diastolic BP were 136.4 ± 17.9 and 80.6 ± 11.6 mmHg, respectively. BP was controlled in 58.3% of those with good adherence compared to 50.2% in those with poor adherence (p = .014). Based on multiple linear regression analysis, female gender (β = -0.72, 95% confidence interval [CI] -1.30, -0.15, p = .014), older age (β = -0.05, 95% CI -0.07, -0.03, p 
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