Displaying publications 1 - 20 of 69 in total

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  1. Teh KH, Ruben JK, Chan CK, Abbas AA
    Malays Orthop J, 2020 Jul;14(2):134-137.
    PMID: 32983389 DOI: 10.5704/MOJ.2007.022
    Avascular necrosis and non-union are two most dreaded complications of femoral neck fracture fixations. Hip replacement seems to be a simple solution for this complex problem. However, the long-term efficacy of prosthetic replacement in the young population with higher functional demand is still questionable. Femoral head preserving valgus subtrochanteric osteotomies in properly selected cases have strong support from literature. The conventional technique of valgus subtrochanteric osteotomy involves lateral based wedge resection. Alternatively, a simpler sliding oblique subtrochanteric osteotomy without any wedge removal can also be performed. We hereby describe a successful case of sliding subtrochanteric osteotomy with 135° dynamic hip screw (DHS) plate fixation in treating non-union neck of femur fracture in a young gentleman.
  2. Goh BH, Chan CK, Kamarudin MN, Abdul Kadir H
    J Ethnopharmacol, 2014 Apr 28;153(2):375-85.
    PMID: 24613274 DOI: 10.1016/j.jep.2014.02.036
    Swietenia macrophylla King is a traditional herb used to treat various diseases including hypertension, diabetes and cancer. Previous study demonstrated its anti-tumor effect but the potential mechanisms have not been clearly defined. The current study was to further investigate the underlying mechanism of ethyl acetate fraction of Swietenia macrophylla (SMEAF)-induced anti-proliferative effect and apoptosis in HCT116 colorectal carcinoma cell.
  3. Chan CK, Chan G, Awang K, Abdul Kadir H
    Molecules, 2016 Mar 21;21(3):385.
    PMID: 27007366 DOI: 10.3390/molecules21030385
    Deoxyelephantopin (DET), one of the major sesquiterpene lactones derived from Elephantopus scaber was reported to possess numerous pharmacological functions. This study aimed to assess the apoptosis inducing effects and cell cycle arrest by DET followed by elucidation of the mechanisms underlying cell death in HCT116 cells. The anticancer activity of DET was evaluated by a MTT assay. Morphological and biochemical changes were detected by Hoescht 33342/PI and Annexin V/PI staining. The results revealed that DET and isodeoxyelephantopin (isoDET) could be isolated from the ethyl acetate fraction of E. scaber leaves via a bioassay-guided approach. DET induced significant dose- and time-dependent growth inhibition of HCT116 cells. Characteristics of apoptosis including nuclear morphological changes and externalization of phosphatidylserine were observed. DET also significantly resulted in the activation of caspase-3 and PARP cleavage. Additionally, DET induced cell cycle arrest at the S phase along with dose-dependent upregulation of p21 and phosphorylated p53 protein expression. DET dose-dependently downregulated cyclin D1, A2, B1, E2, CDK4 and CDK2 protein expression. In conclusion, our data showed that DET induced apoptosis and cell cycle arrest in HCT116 colorectal carcinoma, suggesting that DET has potential as an anticancer agent for colorectal carcinoma.
  4. Ahmad Hidayat AF, Chan CK, Mohamad J, Abdul Kadir H
    Biomed Pharmacother, 2018 Aug;104:806-816.
    PMID: 29860114 DOI: 10.1016/j.biopha.2018.05.073
    Dioscorea bulbifera, also known as air potato, has been cultivated as food crop mainly in tropical countries in Asia and Australia. The tubers are edible and have often been used in Traditional Chinese Medicine (TCM) and Ayurvedic medicine to treat cancer, diabetes, thyroid disease, and inflammation. This study aimed to investigate the effects of D. bulbifera on HCT116 human colorectal carcinoma cells and to unravel the plausible mechanisms underlying its apoptotic effects. The ethanol crude and fractions (hexane, ethyl acetate and water) of D. bulbifera were subjected to cell viability MTT assay against various cancer cell lines. The lowest IC50 of the extract and fractions on selected cancer cells were selected for further apoptosis assay and western blot analysis. HCT116 cancer cells were treated with D. bulbifera and stained with Annexin/PI or Hoechst 33342/PI for preliminary confirmation of apoptosis. The dissipation of mitochondria membrane potential (MMP) was determined by flow cytometry. The protein expressions of apoptosis-related proteins such as Bcl-2 family, caspases, Fas, PARP, ERK1/2 and JNK were detected by western blot analysis. Moreover, the HCT116 cells were treated with UO126 and SP600125 inhibitors to verify the involvement of ERK1/2 and JNK protein expressions in inducing apoptotic cell death. Based on the result, D. bulbifera ethyl acetate fraction (DBEAF) exhibited the most compelling cytotoxicity on HCT116 cells with an IC50 of 37.91 ± 1.30 µg/mL. The induction of apoptosis was confirmed by phosphatidylserine externalization and chromatin condensation. Depolarization of MMP further conferred the induction of apoptosis was through the regulation of Bcl-2 family proteins. Activation of caspase cascades (caspase-3, -9, -8 and -10) was elicited followed by the observation of cleaved PARP accumulation in DBEAF-treated cells. Furthermore, death receptor, Fas was activated upon exposure to DBEAF. Collective apoptotic evidences suggested the involvement of intrinsic and extrinsic pathways by DBEAF in HCT116 cells. Interestingly, the attenuation of ERK1/2 phosphorylation accompanied by the activation of JNK was detected in DBEAF-treated cells. In conclusion, the findings revealed that DBEAF induced apoptosis through intrinsic and extrinsic pathways involving ERK1/2 and JNK.
  5. Ho LY, Chu PS, Consigliere DT, Zainuddin ZM, Bolong D, Chan CK, et al.
    World J Urol, 2018 Jan;36(1):79-86.
    PMID: 29051978 DOI: 10.1007/s00345-017-2097-2
    PURPOSE: The overall objective of the survey was to systematically examine patients' perspectives on lower urinary tract symptoms (LUTS) and their treatment in Southeast Asia.
    METHODS: A multinational cross-sectional survey involving adult men seeking consultation at urology outpatient clinics because of LUTS in Southeast Asia was conducted using convenience sampling. Self-reported prevalence, bother, treatment and treatment satisfaction of selected LUTS including urgency, nocturia, slow stream, and post-micturition dribble were evaluated.
    RESULTS: In total, 1535 eligible patients were enrolled in the survey. A majority of respondents were aged 56-75 years, not employed, and had not undergone prostate operation before. Overall, the self-reported prevalence of nocturia was 88% (95% CI 86-90%), slow stream 61% (95% CI 59-63%), post micturition dribble 55% (95% CI 52-58%), and urgency 52% (95% CI 49-55%). There were marked differences in the country specific prevalence of LUTS complaints. Frequently, symptoms coexisted and were combined with nocturia. More than half of patients felt at least some degree of bother from their symptoms: 61% for urgency, 57% for nocturia, 58% for slow stream, and 60% for post-micturition dribble. Before seeing the present urologists, nearly half of patients have received some form of prescribed treatment and more than 80% of patients indicated they would like to receive treatment.
    CONCLUSION: Men who sought urologist care for LUTS often presented with multiple symptoms. Nocturia emerged as the most common symptom amongst the four core symptoms studied.
    Study site in Malaysia: Urology clinic, Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
  6. Tukur I, Chan CK, Tinsu T, Muhammed-Baba T, Aderemi Ijaiya M
    Iran J Public Health, 2016 May;45(5):586-95.
    PMID: 27398331
    In many sub-Saharan African countries the rate of antenatal care (ANC) has been increased but skilled birth attendance rate is still low. The objective of this study was to evaluate the reasons why women prefer home delivery when facility based delivery is available at minimal cost.
  7. Chan CK, Mohamed RM, Azlina AA, Azhar MM
    Malays Orthop J, 2016 Nov;10(3):42-45.
    PMID: 28553448 MyJurnal DOI: 10.5704/MOJ.1611.004
    Multicentric disappearing bone disease, or Gorham disease, is a rare entity. A middle age woman, presented to us with left sided antalgic gait and severe bony deformity of her left knee. Radiograph revealed massive bone defect of the medial condyle of the left tibia with subluxation of the knee joint. She was scheduled for knee replacement in six months. However, she developed another lesion over the right hip that typically mimicked the disease progression of disappearing bone disease. The right femoral head vanished progressively within three months without significant history of infection or trauma. Subsequent bone biopsy of the right femoral head and left tibia condyle confirmed the diagnosis. Total knee replacement was carried out for her left knee. She remained pain free on her left knee. A year later, after confirming by sequential radiographs that the osteolysis had stopped, total right hip replacement was performed. Five years later, she remained pain free and both the arthroplasties were stable.
  8. Choo SW, Chong JL, Gaubert P, Hughes AC, O'Brien S, Chaber AL, et al.
    Sci Total Environ, 2022 Feb 14.
    PMID: 35176378 DOI: 10.1016/j.scitotenv.2022.153666
  9. Chan CK, Cameron LD
    J Behav Med, 2012 Jun;35(3):347-63.
    PMID: 21695405 DOI: 10.1007/s10865-011-9360-6
    Self-regulation theory and research suggests that different types of mental imagery can promote goal-directed behaviors. The present study was designed to compare the efficacy of approach imagery (attainment of desired goal states) and process imagery (steps for enacting behavior) in promoting physical activity among inactive individuals. A randomized controlled trial was conducted with 182 inactive adults who received one of four interventions for generating mental images related to physical activity over a 4-week period, with Approach Imagery (approach versus neutral) and Process Imagery (process versus no process) as the intervention strategies. Participants received imagery training and practiced daily. Repeated measures ANOVAs revealed that Approach Imagery: (1) increased approach motivations for physical activity at Week 4; (2) induced greater intentions post-session, which subsequently induced more action planning at Week 4; (3) enhanced action planning when combined with process images at post-session and Week 1; and (4) facilitated more physical activity at Week 4 via action planning. These findings suggest that inducing approach orientation via mental imagery may be a convenient and low-cost technique to promote physical activity among inactive individuals.
  10. Zaghlul N, Goh SL, Razman R, Danaee M, Chan CK
    PLoS One, 2023;18(1):e0280361.
    PMID: 36649257 DOI: 10.1371/journal.pone.0280361
    The validity and reliability of the Lafayette stability platform are well-established for double leg testing. However, no evaluation of single leg (SL) stance on the platform was discovered yet. Therefore, this study aimed to investigate the reliability of conducting the SL stance on the Lafayette platform. Thirty-six healthy and active university students (age 23.2 ± 3.2 years; BMI 21.1 ± 3.1 kg/m2) were tested twice, one week apart (week 1; W1, week 2; W2). They stood on their dominant leg with eyes-open (EO) and eyes-closed (EC) in random order. Three successful trials of 20 seconds each were recorded. The duration during which the platform was maintained within 0° of tilt was referred to as time in balance (TIB). At all-time points, TIB was consistently longer in EO (EOW1: 17.02 ± 1.04s; EOW2: 17.32 ± 1.03s) compared to EC (ECW1: 11.55 ± 1.73s; ECW2: 13.08 ± 1.82s). A ±10 seconds difference was demonstrated in the Bland-Altman analysis in both EO and EC. Lower standard error of measurement (SEM) and coefficient of variation (CV) indicated consistent output. High intraclass correlation coefficient (ICC) values were seen between weeks (EO = 0.74; EC = 0.76) and within weeks (EOW1 = 0.79; EOW2 = 0.86; ECW1 = 0.71; ECW2 = 0.71). Although statistical measures (i.e., SEM, CV, and ICC) indicated good reliability of Lafayette for SL tasks, the wide agreement interval is yet to be clinically meaningful. Factors underlying the wide variation need to be identified before Lafayette is used for TIB assessment.
  11. Fan Q, Wider W, Chan CK
    Front Psychol, 2023;14:1181930.
    PMID: 37780163 DOI: 10.3389/fpsyg.2023.1181930
    This paper presents a literature review on the topic of organizational performance. The study conceptualizes the overall performance of the organization as comprising of organizational citizenship behaviors (OCB) and counterproductive work behaviors (CWB). While there are numerous research studies on OCB, not many have focused on how OCB and CWB affect organizational performance simultaneously. The paper provides an explanation of the OCB and CWB concepts, followed by the primary research and focus of the study. The article presents a comprehensive framework for understanding the meanings of OCB and CWB, along with an internal hierarchy. This framework will serve as a beneficial resource for working managers, academics, and researchers, who seek to optimize economic productivity through improved understanding and management of OCB and CWB.
  12. Chan CK
    New Solut, 2002;12(2):109-19.
    PMID: 17208760
    On June 27, 2001, the World Health Organization conducted hearings in Geneva for a Special Report on Genomics & Health. Initially intended as a document to address the ethical, legal, and social implications of the gathering genomics resolution (ELSI), the terms of reference of the report were significantly modified to give primary emphasis to a scientific and technological assessment of the implications of genomics for human health. The Citizens' Health Initiative, one of two NGOs invited to make submissions at these consultations, suggested that no less important than the scientific and technical assessment was a perspective which gave due attention to the social context and political economy of scientific/technological development and its deployment. The article below touches upon neglected health priorities of poor countries, intellectual property rights and patents, risk management, insurance and discrimination, and predictive (prenatal) testing, reproductive choice, and eugenics.
  13. Chen Y, Phang WM, Mu AK, Chan CK, Low BS, Sasidharan S, et al.
    Front Pharmacol, 2015;6:211.
    PMID: 26441666 DOI: 10.3389/fphar.2015.00211
    Eurycoma longifolia is a Malaysian native herb that has been widely used as an aphrodisiac and a remedy for andropause. Although the physiological effects of the plant extract were predicted as a result of the alterations in protein expression, the key protein(s) involved in these alterations are still unclear. In the present study, we have investigated the effect of standardized E. longifolia extract on serum protein expression up to 28 days following oral administration in rats. Serum protein profiles were analyzed by 2-dimensional electrophoresis, and altered proteins were identified via mass spectrometry. We observed that alpha-2-HS glycoprotein (AHS) was significantly decreased in the serum of experimentally treated rats compared to pre-treated animals. Moreover, reduction in AHS was confirmed using competitive enzyme-linked immunosorbent assay. AHS expression is known to be associated with insulin resistance and diabetes. Our data indicated that serum AHS was reduced in rats treated with standardized E. longifolia extract, and therefore form a prelude for further investigation into the effects of this natural extract in animal models involving infertility and diabetes.
  14. Kwan M, Chan C, Ng W, Merican A, Chung W, Chan S
    Malays Orthop J, 2013 Jul;7(2):12-7.
    PMID: 25722819 MyJurnal DOI: 10.5704/MOJ.1307.008
    There are reported cases of cortical reaction over the tension side of the normal femoral shafts in patients on long term treatment with alendronate, leading to subsequent femoral shaft fractures. We performed a retrospective review of patients with low-energy femoral shaft fracture on alendronate, admitted to our institution during the period 2004 to May 2009. The presence of radiological changes of cortical hypertrophy with or without Looser's zone over the tension side of the femoral bone (normal limb) was determined and correlated with clinical symptoms. Thirteen patients were identified. Average duration of alendronate use was 6.5 ± 3.3 years (ranges, two to 10 years). These radiological changes were noted in four patients. Average duration of alendronate usage in these four patients was 6.5 ± 2.4 years (ranges, 5 to10 years). Prodromal thigh pain was present in a patient, who had cortical hypertrophy with the presence of a Looser's zone traversing the cortex on the femoral shaft. One patient had Looser's zone limited at the lateral hypertrophied cortex without prodromal pain. The interobserver kappa coefficient was 0.96. A femoral radiograph should be performed in all patients who are on long-term alendronate therapy who present with thigh pain. We propose a new grading system based on our observation of the radiological features in these four cases. This new grading of the radiological spectrum of femoral shaft cortical pathology has the potential to stratify the risk of low energy femoral fracture for patients treated with long-term alendronate therapy.
  15. Jiang BH, Hsiao FC, Lin YR, Lin CH, Shen YA, Hsu YY, et al.
    ACS Appl Mater Interfaces, 2023 Mar 01;15(8):10907-10917.
    PMID: 36700551 DOI: 10.1021/acsami.2c20527
    Near-infrared (NIR) small-molecule acceptors that absorb at wavelengths of up to 1000 nm are attractive for applications in organic photodetectors (OPDs) and biometrics. In this study, we incorporated IEICO-4F as the third component for PffBT4T-2OD:PC71BM-based OPDs to provide an efficient NIR response while greatly suppressing the leakage current at reverse bias. By varying the blend ratio and thickness (250-600 nm), we obtained an NIR OPD displaying an ultralow dark-current density (JD = 2.62 nA cm-2), ultrahigh detectivity [D* = 7.2 × 1012 Jones (850 nm)], high sensitivity, and photoresponsivity covering the region from the ultraviolet to the NIR. We used tapping-mode atomic force microscopy, optical microscopy, grazing-incidence wide-angle X-ray scattering, and contact angle measurements to investigate the effect of IEICO-4F on the performance of the ternary OPDs. The low compatibility of PffBT4T-2OD and IEICO-4F, originating from weak intermolecular interactions, allowed us to manipulate the degree of phase separation between the donor and acceptor in the ternary blends, leading to an optimized blend morphology featuring efficient charge separation, transport, and collection. To demonstrate its applicability, we integrated our OPD with two light-emitting diodes and used the system for precisely calculated transmissive pulse oximetry.
  16. Chan CK, Singh J, Rasid BK, Devaraj T
    Med J Malaysia, 1994 Jun;49(2):122-31.
    PMID: 8090090
    2,124 cases of cancer diagnosed and/or treated in Penang between 1987-1990 were reported to the National Cancer Registry of Malaysia by hospitals in Penang. 1,762 met the criteria for Penang incident cases first diagnosed between 1987-1990, and were the subjects on which all subsequent analyses were based. 85 per cent of case notifications were from Mount Miriam Hospital. Among males, all-site cancer incidence rates (age-standardised) were highest among Chinese, and lowest among Malays. Among females, the Indian female incidence rate was highest, higher than that of any other ethnic-gender sub-group. Site-specific cancer rates varied according to ethnicity and gender, but overall the four most frequent cancers reported from Penang were breast, lung, cervix and nasopharynx cancers. It needs to be emphasised that all these results are highly tentative since they are based on notified cancer occurrences and hence are very uncertain proxies for true cancer incidence. Based on incidence rates from the Singapore Cancer Registry (1978-1982), the expected number of incident cases in 1989 for Penang (Malays, Chinese and Indians combined) was 1,561. The number notified to the National Cancer Registry was 496. This underlines the tentative nature of this analysis of the returns for 1987-1990 from Penang.
  17. Tay KC, Tan LT, Chan CK, Hong SL, Chan KG, Yap WH, et al.
    Front Pharmacol, 2019;10:820.
    PMID: 31402861 DOI: 10.3389/fphar.2019.00820
    Cancer, a complex yet common disease, is caused by uncontrolled cell division and abnormal cell growth due to a variety of gene mutations. Seeking effective treatments for cancer is a major research focus, as the incidence of cancer is on the rise and drug resistance to existing anti-cancer drugs is major concern. Natural products have the potential to yield unique molecules and combinations of substances that may be effective against cancer with relatively low toxicity/better side effect profile compared to standard anticancer therapy. Drug discovery work with natural products has demonstrated that natural compounds display a wide range of biological activities correlating to anticancer effects. In this review, we discuss formononetin (C16H12O4), which originates mainly from red clovers and the Chinese herb Astragalus membranaceus. The compound comes from a class of 7-hydroisoflavones with a substitution of methoxy group at position 4. Formononetin elicits antitumorigenic properties in vitro and in vivo by modulating numerous signaling pathways to induce cell apoptosis (by intrinsic pathway involving Bax, Bcl-2, and caspase-3 proteins) and cell cycle arrest (by regulating mediators like cyclin A, cyclin B1, and cyclin D1), suppress cell proliferation [by signal transducer and activator of transcription (STAT) activation, phosphatidylinositol 3-kinase/protein kinase-B (PI3K/AKT), and mitogen-activated protein kinase (MAPK) signaling pathway], and inhibit cell invasion [by regulating growth factors vascular endothelial growth factor (VEGF) and Fibroblast growth factor 2 (FGF2), and matrix metalloproteinase (MMP)-2 and MMP-9 proteins]. Co-treatment with other chemotherapy drugs such as bortezomib, LY2940002, U0126, sunitinib, epirubicin, doxorubicin, temozolomide, and metformin enhances the anticancer potential of both formononetin and the respective drugs through synergistic effect. Compiling the evidence thus far highlights the potential of formononetin to be a promising candidate for chemoprevention and chemotherapy.
  18. Tan LT, Chan KG, Chan CK, Khan TM, Lee LH, Goh BH
    Biomed Res Int, 2018;2018:4823126.
    PMID: 29805975 DOI: 10.1155/2018/4823126
    Mangrove derived microorganisms constitute a rich bioresource for bioprospecting of bioactive natural products. This study explored the antioxidant potentials of Streptomyces bacteria derived from mangrove soil. Based on 16S rRNA phylogenetic analysis, strain MUM292 was identified as the genus Streptomyces. Strain MUM292 showed the highest 16S rRNA gene sequence similarity of 99.54% with S. griseoruber NBRC12873T. Furthermore, strain MUM292 was also characterized and showed phenotypic characteristics consistent with Streptomyces bacteria. Fermentation and extraction were performed to obtain the MUM292 extract containing the secondary metabolites of strain MUM292. The extract displayed promising antioxidant activities, including DPPH, ABTS, and superoxide radical scavenging and also metal-chelating activities. The process of lipid peroxidation in lipid-rich product was also retarded by MUM292 extract and resulted in reduced MDA production. The potential bioactive constituents of MUM292 extract were investigated using GC-MS and preliminary detection showed the presence of pyrazine, pyrrole, cyclic dipeptides, and phenolic compound in MUM292 extract. This work demonstrates that Streptomyces MUM292 can be a potential antioxidant resource for food and pharmaceutical industries.
  19. Tan LT, Chan CK, Chan KG, Pusparajah P, Khan TM, Ser HL, et al.
    Cancers (Basel), 2019 Nov 06;11(11).
    PMID: 31698795 DOI: 10.3390/cancers11111742
    New and effective anticancer compounds are much needed as the incidence of cancer continues to rise. Microorganisms from a variety of environments are promising sources of new drugs; Streptomyces sp. MUM256, which was isolated from mangrove soil in Malaysia as part of our ongoing efforts to study mangrove resources, was shown to produce bioactive metabolites with chemopreventive potential. This present study is a continuation of our previous efforts and aimed to investigate the underlying mechanisms of the ethyl acetate fraction of MUM256 crude extract (MUM256 EA) in inhibiting the proliferation of HCT116 cells. Our data showed that MUM256 EA reduced proliferation of HCT116 cells via induction of cell-cycle arrest. Molecular studies revealed that MUM256 EA regulated the expression level of several important cell-cycle regulatory proteins. The results also demonstrated that MUM256 EA induced apoptosis in HCT116 cells mediated through the intrinsic pathway. Gas chromatography-mass spectrometry (GC-MS) analysis detected several chemical compounds present in MUM256 EA, including cyclic dipeptides which previous literature has reported to demonstrate various pharmacological properties. The cyclic dipeptides were further shown to inhibit HCT116 cells while exerting little to no toxicity on normal colon cells in this study. Taken together, the findings of this project highlight the important role of exploring the mangrove microorganisms as a bioresource which hold tremendous promise for the development of chemopreventive drugs against colorectal cancer.
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