Displaying publications 21 - 40 of 45 in total

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  1. Total cell pooling in vitro: an effective isolation method for bone marrow-derived multipotent stromal cells
    Wee AS, Lim CK, Merican AM, Ahmad TS, Kamarul T
    In Vitro Cell Dev Biol Anim, 2013 Jun;49(6):424-32.
    PMID: 23708918 DOI: 10.1007/s11626-013-9626-0
    In vitro cellular proliferation and the ability to undergo multilineage differentiation make bone marrow-derived multipotent stromal cells (MSCs) potentially useful for clinical applications. Several methods have been described to isolate a homogenous bone marrow-derived MSCs population; however, none has been proven most effective, mainly due to their effects on proliferation and differentiation capability of the isolated cells. It is hypothesized that our newly established total cell pooling method may provide a better alternative as compared to the standard isolation method (density gradient centrifugation method). For the total cell pooling method, MSCs were isolated from rabbit bone marrow and were subsequently cultured in the growth medium without further separation as in the standard isolation method. The total cell pooling method was 65 min faster than the standard isolation method in completing cell isolation. Nevertheless, both methods did not differ significantly in the number of primary viable cells and population doubling time in the cultures (p > 0.05). The isolated cells from both methods expressed CD29 and CD44 markers, but not CD45 markers. Furthermore, they displayed multilineage differentiation characteristics of chondroblasts, osteoblasts, and adipocytes. In conclusion, both methods provide similar efficiency in the isolation of rabbit bone marrow-derived MSCs; however, the total cell pooling method is technically simpler and more cost effective than the standard isolation method.
  2. Clinical and radiological features of imported chikungunya fever in Japan: a study of six cases at the National Center for Global Health and Medicine
    Mizuno Y, Kato Y, Takeshita N, Ujiie M, Kobayashi T, Kanagawa S, et al.
    J Infect Chemother, 2011 Jun;17(3):419-23.
    PMID: 20862507 DOI: 10.1007/s10156-010-0124-y
    Chikungunya fever (CHIKF) is currently distributed in Africa and in South and Southeast Asia; outbreaks have occurred periodically in the region over the past 50 years. After a large outbreak had occurred in countries in the western Indian Ocean region in 2005, several countries reported cases of CHIKF from travelers who had visited affected areas. In Japan, there have been only 15 cases of CHIKF patients so far, according to the National Institute of Infectious Diseases. Therefore, to evaluate the clinical and radiological features associated with the disease, we describe 6 imported cases of CHIKF. All of the patients had had prolonged arthralgia on admission to our hospital, and diagnosis was confirmed with specific antibodies by using an IgM-capture enzyme-linked immunoassay and a plaque reduction neutralizing antibody assay. Magnetic resonance imaging (MRI) of one patient revealed erosive arthritis and tenosynovitis during the convalescence stage. Clinicians should be aware of the late consequences of infection by the chikungunya virus (CHIKV) and recognize the possible association of subacute and chronic arthritis features. In addition, competent vectors of CHIKV, Aedes aegypti, can now be found in many temperate areas of the eastern and western hemispheres, including Japan. This fact raises concern that the virus could be introduced and become established in these areas. This necessitates an increased awareness of the disease, because imported cases are likely to contribute to the spread of CHIKV infection wherever the competent mosquito vectors are distributed.
  3. Report: Cytotoxic activity of phytochemicals from the stem bark of Calophyllum castaneum
    Lim CK, Gan SY, Yi V, Jong M, Leong CO, Mai CW, et al.
    Pak J Pharm Sci, 2019 Sep;32(5):2183-2187.
    PMID: 31813886
    Phytochemical investigation on the dichloromethane stem bark extract of Calophyllum castaneum resulted in the isolation of five compounds, namely isoblancoic acid (1), blancoic acid (2), euxanthone (3), friedelin (4) and friedelinol (5). All these compounds were isolated for the first time from this plant. Their chemical structures were elucidated based on the spectroscopic analyses. The cytotoxicity of compounds 1-5 was assessed on a panel of cancer cell lines including bone (Saos-2, mg63), colorectal (HT29, Caco-2, HCC2998, SW48, HCT116, KM12), liver (HepG2), lung (H1299, Calu-3), and brain (C6), using 5-fluorouracil as positive control. Pronounced antiproliferative activities were observed for compound 1 which exhibited a comparable activity with the positive control, against brain (C6) and colorectal (SW48, KM12, HCT116) cancer cell lines showing IC50 values in the range of 14 to 65μM. Meanwhile, compound 5 displayed a greater cytotoxic effect showing at least 2-fold more strongly than the positive control, against C6 brain cancer cells. The assay findings have unveiled the therapeutic value of phytochemicals from Calophyllum castaneum as anti-cancer agents.
  4. Fulltext Bioelectrical Impedance Analysis Derived-Phase Angle as a Pragmatic Tool to Detect Protein Energy Wasting among Multi-Ethnic Hemodialysis Patients
    Lim CK, Lim JH, Ibrahim I, Chan YM, Zakaria NF, Yahya R, et al.
    Diagnostics (Basel), 2021 Sep 23;11(10).
    PMID: 34679443 DOI: 10.3390/diagnostics11101745
    Protein-energy wasting (PEW) is a devastating metabolic derangement that leads to increased morbidity and mortality in hemodialysis (HD) patients. This study aimed to determine the diagnostic test accuracy of bioelectrical impedance analysis derived-phase angle (PhA) in detecting PEW among HD patients. This was a multi-centre, cross-sectional study conducted amongst 152 multi-ethnic HD patients in Klang Valley, Malaysia. PEW was assessed using the International Society of Renal Nutrition and Metabolism criteria as the reference method. PhA was measured using a multi-frequency bioelectrical impedance spectroscopy at 50 kHz. Multiple and logistic regressions were used to determine factors associated with PhA and PEW diagnosis, respectively. A receiver operating characteristics curve analysis was used to establish the gender-specific PhA cut-offs to detect PEW. PEW existed in 21.1% of the HD patients. PhA was found as an independent predictor of PEW (adjOR = 0.308, p = 0.001), with acceptable to excellent discriminative performance (adjAUCmale = 0.809; adjAUCfemale = 0.719). Male patients had higher PhA cut-off compared to female patients (4.26° vs. 3.30°). We concluded that PhA is a valid and pragmatic biomarker to detect PEW in multi-ethnic Malaysian HD patients and a gender-specific cut-off is necessary, attributed to the gender differences in body composition.
  5. Postprandial increases in nitrogenous excretion and urea synthesis in the giant mudskipper Periophthalmodon schlosseri
    Ip YK, Lim CK, Lee SL, Wong WP, Chew SF
    J Exp Biol, 2004 Aug;207(Pt 17):3015-23.
    PMID: 15277556
    The objective of this study was to determine the effects of feeding on the excretory nitrogen (N) metabolism of the giant mudskipper, Periophthalmodon schlosseri, with special emphasis on the role of urea synthesis in ammonia detoxification. The ammonia and urea excretion rates of P. schlosseri increased 1.70- and 1.92-fold, respectively, within the first 3 h after feeding on guppies. Simultaneously, there were significant decreases in ammonia levels in the plasma and the brain, and in urea contents in the muscle and liver, of P. schlosseri at 3 h post-feeding. Thus, it can be concluded that P. schlosseri was capable of unloading ammonia originally present in some of its tissues in anticipation of ammonia released from the catabolism of excess amino acids after feeding. Subsequently, there were significant increases in urea content in the muscle, liver and plasma (1.39-, 2.17- and 1.62-fold, respectively) at 6 h post-feeding, and the rate of urea synthesis apparently increased 5.8-fold between 3 h and 6 h. Increased urea synthesis might have occurred in the liver of P. schlosseri because the greatest increase in urea content was observed therein. The excess urea accumulated in the body at 6 h was completely excreted between 6 and 12 h, and the percentage of waste-N excreted as urea-N increased significantly to 26% during this period, but never exceeded 50%, the criterion for ureotely, meaning that P. schlosseri remained ammonotelic after feeding. By 24 h, 62.7% of the N ingested by P. schlosseri was excreted, out of which 22.6% was excreted as urea-N. This is the first report on the involvement of increased urea synthesis and excretion in defense against ammonia toxicity in the giant mudskipper, and our results suggest that an ample supply of energy resources, e.g. after feeding, is a prerequisite for the induction of urea synthesis. Together, increases in nitrogenous excretion and urea synthesis after feeding effectively prevented a postprandial surge of ammonia in the plasma of P. schlosseri as reported previously for other fish species. Consequently, contrary to previous reports, there were significant decreases in the ammonia content of the brain of P. schlosseri throughout the 24 h period post-feeding, accompanied by a significant decrease in brain glutamine content between 12 h and 24 h.
  6. TGF-β1 and -β3 for Mesenchymal Stem Cells Chondrogenic Differentiation on Poly (Vinyl Alcohol)-Chitosan-Poly (Ethylene Glycol) Scaffold
    Wee AS, Lim CK, Tan SL, Ahmad TS, Kamarul T
    Tissue Eng Part C Methods, 2022 10;28(10):501-510.
    PMID: 36082992 DOI: 10.1089/ten.TEC.2022.0112
    Transforming growth factor-beta 1 (TGF-β1) has been reported to promote chondrogenic differentiation and proliferation in the multipotent stromal cell (MSCs), and the transforming growth factor-beta 3 (TGF-β3) tends to be exclusively in promoting cell differentiation alone. The objective of this study was to determine the effect of TGF-β1 and -β3 on the MSCs chondrogenic differentiation on the poly (vinyl alcohol)-chitosan-poly (ethylene glycol) (PVA-NOCC-PEG) scaffold, compared with that of monolayer and pellet cultures. In this study, P2 rabbit bone marrow-derived MSCs were seeded either on the untreated six-well plate (for monolayer culture) or onto the PVA-NOCC-PEG scaffold or cultured as a pellet culture. The cultures were maintained in a chemically defined serum-free medium supplemented with 10 ng/mL of either TGF-β1 or TGF-β3. Cell viability assay, biochemical assay, and real-time polymerase chain reaction were performed to determine the net effect of cell proliferation and chondrogenic differentiation of each of the growth factors. The results showed that the PVA-NOCC-PEG scaffold enhanced MSCs cell proliferation from day 12 to 30 (p  0.05). In terms of chondrogenic differentiation, the PVA-NOCC-PEG scaffold augmented the GAGs secretion in MSCs and the mRNA expression levels of Sox9, Col2a1, Acan, and Comp were elevated (p  0.05). In conclusion, TGF-β1 and TGF-β3 enhanced the chondrogenic differentiation of MSCs seeded on the PVA-NOCC-PEG scaffold; however, there was no significant difference between the effect of TGF-β1 and TGF-β3. Impact statement Transforming growth factor-beta (TGF-β) superfamily members is a key requirement for the in vitro chondrogenic differentiation of mesenchymal stem cells (MSCs). In this study, the effects of TGF-β1 and -β3 on MSC chondrogenic differentiation and proliferation on a novel three-dimensional scaffold, the poly(vinyl alcohol)-chitosan-poly(ethylene glycol) (PVA-NOCC-PEG) scaffold, was evaluated. In this study, the results showed both TGF-β1 and TGF-β3 can enhance the chondrogenic differentiation of MSCs seeded on the PVA-NOCC-PEG scaffold.
  7. Molecular characterization of glycation-associated skin ageing: an alternative skin model to study in vitro antiglycation activity of topical cosmeceutical and pharmaceutical formulations
    Lee KH, Ng YP, Cheah PS, Lim CK, Toh MS
    Br J Dermatol, 2017 Jan;176(1):159-167.
    PMID: 27363533 DOI: 10.1111/bjd.14832
    BACKGROUND: Glycation is a nonenzymatic reaction that cross-links a sugar molecule and protein macromolecule to form advanced glycation products (AGEs) that are associated with various age-related disorders; thus glycation plays an important role in skin chronological ageing.

    OBJECTIVES: To develop a novel in vitro skin glycation model as a screening tool for topical formulations with antiglycation properties and to further characterize, at the molecular level, the glycation stress-driven skin ageing mechanism.

    METHODS: The glycation model was developed using human reconstituted full-thickness skin; the presence of N(ε) -(carboxymethyl) lysine (CML) was used as evidence of the degree of glycation. Topical application of emulsion containing a well-known antiglycation compound (aminoguanidine) was used to verify the sensitivity and robustness of the model. Cytokine immunoassay, quantitative real-time polymerase chain reaction and histological analysis were further implemented to characterize the molecular mechanisms of skin ageing in the skin glycation model.

    RESULTS: Transcriptomic and cytokine profiling analyses in the skin glycation model demonstrated multiple biological changes, including extracellular matrix catabolism, skin barrier function impairment, oxidative stress and subsequently the inflammatory response. Darkness and yellowness of skin tone observed in the in vitro skin glycation model correlated well with the degree of glycation stress.

    CONCLUSIONS: The newly developed skin glycation model in this study has provided a new technological dimension in screening antiglycation properties of topical pharmaceutical or cosmeceutical formulations. This study concomitantly provides insights into skin ageing mechanisms driven by glycation stress, which could be useful in formulating skin antiageing therapy in future studies.

  8. The Cytokines CXCL10 and CCL2 and the Kynurenine Metabolite Anthranilic Acid Accurately Predict Patients at Risk of Developing Dengue With Warning Signs
    Jusof FF, Lim CK, Aziz FN, Soe HJ, Raju CS, Sekaran SD, et al.
    J Infect Dis, 2022 Nov 28;226(11):1964-1973.
    PMID: 35767283 DOI: 10.1093/infdis/jiac273
    BACKGROUND: The resolution or aggravation of dengue infection depends on the patient's immune response during the critical phase. Cytokines released by immune cells increase with the worsening severity of dengue infections. Cytokines activate the kynurenine pathway (KP) and the extent of KP activation then influences disease severity.

    METHODS: KP metabolites and cytokines in plasma samples of patients with dengue infection (dengue without warning signs [DWS-], dengue with warning signs [DWS+], or severe dengue) were analyzed. Cytokines (interferon gamma [IFN-ɣ], tumor necrosis factor, interleukin 6, CXCL10/interferon-inducile protein 10 [IP-10], interleukin 18 [IL-18], CCL2/monocyte chemoattractant protein-1 [MCP-1], and CCL4/macrophage inflammatory protein-1beta [MIP-1β] were assessed by a Human Luminex Screening Assay, while KP metabolites (tryptophan, kynurenine, anthranilic acid [AA], picolinic acid, and quinolinic acid) were assessed by ultra-high-performance liquid chromatography and Gas Chromatography Mass Spectrophotometry [GCMS] assays.

    RESULTS: Patients with DWS+ had increased activation of the KP where kynurenine-tryptophan ratio, anthranilic acid, and picolinic acid were elevated. These patients also had higher levels of the cytokines IFN-ɣ, CXCL10, CCL4, and IL-18 than those with DWS-. Further receiver operating characteristic analysis identified 3 prognostic biomarker candidates, CXCL10, CCL2, and AA, which predicted patients with higher risks of developing DWS+ with an accuracy of 97%.

    CONCLUSIONS: The data suggest a unique biochemical signature in patients with DWS+. CXCL10 and CCL2 together with AA are potential prognostic biomarkers that discern patients with higher risk of developing DWS+ at earlier stages of infection.

  9. Decolorization of palm oil mill effluent using growing cultures of Curvularia clavata
    Neoh CH, Lam CY, Lim CK, Yahya A, Ibrahim Z
    Environ Sci Pollut Res Int, 2014 Mar;21(6):4397-408.
    PMID: 24327114 DOI: 10.1007/s11356-013-2350-1
    Agricultural wastewater that produces color are of environmental and health concern as colored effluent can produce toxic and carcinogenic by-products. From this study, batch culture optimization using response surface methods indicated that the fungus isolated from the pineapple solid waste, Curvularia clavata was able to decolorize sterile palm oil mill effluent (POME) which is mainly associated with polyphenol and lignin. Results showed successful decolorization of POME up to 80 % (initial ADMI [American Dye Manufacturing Index] of 3,793) with 54 % contributed by biosorption and 46 % by biodegradation after 5 days of treatment. Analysis using HPLC and GC-MS showed the degradation of color causing compound such as 3-methoxyphenyl isothiocynate and the production of new metabolites. Ecotoxicity test indicated that the decolorized effluent is safe for discharge. To determine the longevity of the fungus for a prolonged decolorization period, sequential batch decolorization studies were carried out. The results showed that lignin peroxidase and laccase were the main ligninolytic enzymes involved in the degradation of color. Carboxymethyl cellulase (CMCase) and xylanase activities were also detected suggesting possible roles of the enzymes in promoting growth of the fungus which consequently contributed to improved decolorization of POME. In conclusion, the ability of C. clavata in treating color of POME indicated that C. clavata is of potential use for decolorization and degradation of agricultural wastewater containing polyphenolic compounds.
  10. Decolourisation of Acid Orange 7 recalcitrant auto-oxidation coloured by-products using an acclimatised mixed bacterial culture
    Bay HH, Lim CK, Kee TC, Ware I, Chan GF, Shahir S, et al.
    Environ Sci Pollut Res Int, 2014 Mar;21(5):3891-906.
    PMID: 24293297 DOI: 10.1007/s11356-013-2331-4
    This study focuses on the biodegradation of recalcitrant, coloured compounds resulting from auto-oxidation of Acid Orange 7 (AO7) in a sequential facultative anaerobic-aerobic treatment system. A novel mixed bacterial culture, BAC-ZS, consisting of Brevibacillus panacihumi strain ZB1, Lysinibacillus fusiformis strain ZB2, and Enterococcus faecalis strain ZL bacteria were isolated from environmental samples. The acclimatisation of the mixed culture was carried out in an AO7 decolourised solution. The acclimatised mixed culture showed 98 % decolourisation within 2 h of facultative anaerobic treatment using yeast extract and glucose as co-substrate. Subsequent aerobic post treatment caused auto-oxidation reaction forming dark coloured compounds that reduced the percentage decolourisation to 73 %. Interestingly, further agitations of the mixed culture in the solution over a period of 48 h significantly decolourise the coloured compounds and increased the decolourisation percentage to 90 %. Analyses of the degradation compounds using UV-visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR) and high performance liquid chromatography (HPLC) showed complete degradation of recalcitrant AO7 by the novel BAC-ZS. Phytotoxicity tests using Cucumis sativus confirmed the dye solution after post aerobic treatment were less toxic compared to the parent dye. The quantitative real-time PCR revealed that E. faecalis strain ZL was the dominant strain in the acclimatised mix culture.
  11. Biodecolorization of recalcitrant dye as the sole sourceof nutrition using Curvularia clavata NZ2 and decolorization ability of its crude enzymes
    Neoh CH, Lam CY, Lim CK, Yahya A, Bay HH, Ibrahim Z, et al.
    Environ Sci Pollut Res Int, 2015 Aug;22(15):11669-78.
    PMID: 25850745 DOI: 10.1007/s11356-015-4436-4
    Extensive use of recalcitrant azo dyes in textile and paper industries poses a direct threat to the environment due to the carcinogenicity of their degradation products. The aim of this study was to investigate the efficiency of Curvularia clavata NZ2 in decolorization of azo dyes. The ability of the fungus to decolorize azo dyes can be evaluated as an important outcome as existing effluent treatment is unable to remove the dyes effectively. C. clavata has the ability to decolorize Reactive Black 5 (RB5), Acid Orange 7 (AO7), and Congo Red azo dyes, utilizing these as sole sources of carbon and nitrogen. Ultraviolet-visible (UV-vis) spectroscopy and Fourier infrared spectroscopy (FTIR) analysis of the extracted RB5's metabolites along with desorption tests confirmed that the decolorization process occurred due to degradation and not merely by adsorption. Enzyme activities of extracellular enzymes such as carboxymethylcellulase (CMCase), xylanase, laccase, and manganese peroxidase (MnP) were also detected during the decolorization process. Toxicity expressed as inhibition of germination was reduced significantly in fungal-treated azo dye solution when compared with the control. The cultivation of C. clavata under sequential batch system also recorded a decolorization efficiency of above 90%. The crude enzyme secreted by C. clavata also showed excellent ability to decolorize RB5 solutions with concentrations of 100 ppm (88-92%) and 1000 ppm (70-77%) without redox mediator. This proved that extracellular enzymes produced by C. clavata played a major role in decolorization of RB5.
  12. Application of zeolite-activated carbon macrocomposite for the adsorption of Acid Orange 7: isotherm, kinetic and thermodynamic studies
    Lim CK, Bay HH, Neoh CH, Aris A, Abdul Majid Z, Ibrahim Z
    Environ Sci Pollut Res Int, 2013 Oct;20(10):7243-55.
    PMID: 23653315 DOI: 10.1007/s11356-013-1725-7
    In this study, the adsorption behavior of azo dye Acid Orange 7 (AO7) from aqueous solution onto macrocomposite (MC) was investigated under various experimental conditions. The adsorbent, MC, which consists of a mixture of zeolite and activated carbon, was found to be effective in removing AO7. The MC were characterized by scanning electron microscopy (SEM), energy dispersive X-ray, point of zero charge, and Brunauer-Emmett-Teller surface area analysis. A series of experiments were performed via batch adsorption technique to examine the effect of the process variables, namely, contact time, initial dye concentration, and solution pH. The dye equilibrium adsorption was investigated, and the equilibrium data were fitted to Langmuir, Freundlich, and Tempkin isotherm models. The Langmuir isotherm model fits the equilibrium data better than the Freundlich isotherm model. For the kinetic study, pseudo-first-order, pseudo-second-order, and intraparticle diffusion model were used to fit the experimental data. The adsorption kinetic was found to be well described by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption process is a spontaneous and endothermic process. The SEM, Fourier transform infrared spectroscopy, ultraviolet-visible spectral and high performance liquid chromatography analysis were carried out before and after the adsorption process. For the phytotoxicity test, treated AO7 was found to be less toxic. Thus, the study indicated that MC has good potential use as an adsorbent for the removal of azo dye from aqueous solution.
  13. Biosorption and biodegradation of Acid Orange 7 by Enterococcus faecalis strain ZL: optimization by response surface methodological approach
    Lim CK, Bay HH, Aris A, Abdul Majid Z, Ibrahim Z
    Environ Sci Pollut Res Int, 2013 Jul;20(7):5056-66.
    PMID: 23334551 DOI: 10.1007/s11356-013-1476-5
    Reactive dyes account for one of the major sources of dye wastes in textile effluent. In this study, decolorization of the monoazo dye, Acid Orange 7 (AO7) by the Enterococcus faecalis strain ZL that isolated from a palm oil mill effluent treatment plant has been investigated. Decolorization efficiency of azo dye is greatly affected by the types of nutrients and the size of inoculum used. In this work, one-factor-at-a-time (method and response surface methodology (RSM) was applied to optimize these operational factors and also to study the combined interaction between them. Analysis of AO7 decolorization was done using Fourier transform infrared (FTIR) spectroscopy, desorption study, UV-Vis spectral analysis, field emission scanning electron microscopy (FESEM), and high performance liquid chromatography (HPLC). The optimum condition via RSM for the color removal of AO7 was found to be as follows: yeast extract, 0.1% w/v, glycerol concentration of 0.1% v/v, and inoculum density of 2.5% v/v at initial dye concentration of 100 mg/L at 37 °C. Decolorization efficiency of 98% was achieved in only 5 h. The kinetic of AO7 decolorization was found to be first order with respect to dye concentration with a k value of 0.87/h. FTIR, desorption study, UV-Vis spectral analysis, FESEM, and HPLC findings indicated that the decolorization of AO7 was mainly due to the biosorption as well as biodegradation of the bacterial cells. In addition, HPLC analyses also showed the formation of sulfanilic acid as a possible degradation product of AO7 under facultative anaerobic condition. This study explored the ability of E. faecalis strain ZL in decolorizing AO7 by biosorption as well as biodegradation process.
  14. Fulltext Dengue virus infection-enhancing activity in serum samples with neutralizing activity as determined by using FcγR-expressing cells
    Moi ML, Lim CK, Chua KB, Takasaki T, Kurane I
    PLoS Negl Trop Dis, 2012;6(2):e1536.
    PMID: 22389741 DOI: 10.1371/journal.pntd.0001536
    Progress in dengue vaccine development has been hampered by limited understanding of protective immunity against dengue virus infection. Conventional neutralizing antibody titration assays that use FcγR-negative cells do not consider possible infection-enhancement activity. We reasoned that as FcγR-expressing cells are the major target cells of dengue virus, neutralizing antibody titration assays using FcγR-expressing cells that determine the sum of neutralizing and infection-enhancing activity, may better reflect the biological properties of antibodies in vivo.
  15. A new coumarin from stem bark of Mesua hexapetala
    Karunakaran T, Ee GC, Teh SS, Daud S, Mah SH, Lim CK, et al.
    Nat Prod Res, 2016 Jul;30(14):1591-7.
    PMID: 26710827 DOI: 10.1080/14786419.2015.1120727
    A new alkylated coumarin derivative, hexapetarin (1) along with three other xanthones, trapezifolixanthone (2), cudraxanthone G (3) and 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4), and four common triterpenoids, friedelin (5), stigmasterol (6), beta-sitosterol (7) and gamma-sitosterol (8) were isolated from the stem bark of Mesua hexapetala (Clusiaceae), a plant, native to Malaysia. The structures of these compounds were elucidated and determined using spectroscopic techniques such as NMR and MS. Anti-inflammatory activity assay indicated hexapetarin (1) to possess moderate anti-inflammatory activity, while 1,3,7-trihydroxy-2,4-di (3-methyl-2-butenyl)xanthone (4) gave very good activity.
  16. Fulltext Isolation and enhancement of a homogenous in vitro human Hertwig's epithelial root sheath cell population
    Farea M, Halim AS, Abdullah NA, Lim CK, Mokhtar KI, Berahim Z, et al.
    Int J Mol Sci, 2013;14(6):11157-70.
    PMID: 23712356 DOI: 10.3390/ijms140611157
    Hertwig's epithelial root sheath (HERS) cells play a pivotal role during root formation of the tooth and are able to form cementum-like tissue. The aim of the present study was to establish a HERS cell line for molecular and biochemical studies using a selective digestion method. Selective digestion was performed by the application of trypsin-EDTA for 2 min, which led to the detachment of fibroblast-like-cells, with the rounded cells attached to the culture plate. The HERS cells displayed a typical cuboidal/squamous-shaped appearance. Characterization of the HERS cells using immunofluorescence staining and flow cytometry analysis showed that these cells expressed pan-cytokeratin, E-cadherin, and p63 as epithelial markers. Moreover, RT-PCR confirmed that these cells expressed epithelial-related genes, such as cytokeratin 14, E-cadherin, and ΔNp63. Additionally, HERS cells showed low expression of CD44 and CD105 with absence of CD34 and amelogenin expressions. In conclusion, HERS cells have been successfully isolated using a selective digestion method, thus enabling future studies on the roles of these cells in the formation of cementum-like tissue in vitro.
  17. Supermacroporous poly(vinyl alcohol)-carboxylmethyl chitosan-poly(ethylene glycol) scaffold: an in vitro and in vivo pre-assessments for cartilage tissue engineering
    Lee SY, Wee AS, Lim CK, Abbas AA, Selvaratnam L, Merican AM, et al.
    J Mater Sci Mater Med, 2013 Jun;24(6):1561-70.
    PMID: 23512151 DOI: 10.1007/s10856-013-4907-4
    This study aims to pre-assess the in vitro and in vivo biocompatibility of poly(vinyl alcohol)-carboxylmethyl-chitosan-poly(ethylene glycol) (PCP) scaffold. PCP was lyophilised to create supermacroporous structures. 3-(4, 5-dimethyl-thiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and immunohistochemistry (IHC) were used to evaluate the effectiveness of PCP scaffolds for chondrocytes attachment and proliferation. The ultrastructural was assessed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracellular matrix (ECM) formation was evaluated using collagen type-II staining, glycosaminoglycan (GAG) and collagen assays. Histological analysis was conducted on 3-week implanted Sprague-Dawley rats. The MTT, IHC, SEM and TEM analyses confirm that PCP scaffolds promoted cell attachment and proliferation in vitro. The chondrocyte-PCP constructs secreted GAG and collagen type-II, both increased significantly from day-14 to day-28 (P 
  18. Correlations of HBV genotypes, mutations affecting HBeAg expression and HBeAg/ anti-HBe status in HBV carriers
    Lim CK, Tan JT, Khoo JB, Ravichandran A, Low HM, Chan YC, et al.
    Int J Med Sci, 2006;3(1):14-20.
    PMID: 16421626
    This study was carried out to determine the effects of hepatitis B virus genotypes, core promoter mutations (A1762G1764-->T1762A1764) as well as precore stop codon mutations (TGG-->TAG) on HBeAg expression and HBeAg/ anti-HBe status. Study was also performed on the effects of codon 15 variants (C1858/ T1858) on the predisposition of precore stop codon mutations (TGG-->TAG). A total of 77 sera samples were analyzed. Fifty one samples were successfully genotyped of which the predominant genotype was genotype B (29/ 51, 56.9 %), followed by genotype C (16/ 51, 31.4 %). Co-infections by genotypes B and C were observed in four samples (7.8 %). To a lesser degree, genotypes D and E (2.0 % each) were also observed. For core promoter mutations, the prevalence was 68.8 % (53/ 77) for A1762G1764 wild-type and 14.3 % (11/ 77) for T1762A1764 mutant while 9.1 % (7/ 77) was co-infected by both strains. The prevalence of codon 15 variants was found to be 42.9 % (33/ 77) for T1858 variant and 16.9 % (13/ 77) for C1858 variant. No TAG mutation was found. In our study, no associations were found between genotypes (B and C) and core promoter mutations as well as codon 15 variants. Also no correlation was observed between HBeAg/ anti-HBe status with genotypes (B and C) and core promoter mutations.
  19. Fulltext Limitations of Existing Dialysis Diet Apps in Promoting User Engagement and Patient Self-Management: Quantitative Content Analysis Study
    Lim JH, Lim CK, Ibrahim I, Syahrul J, Mohamed Zabil MH, Zakaria NF, et al.
    JMIR Mhealth Uhealth, 2020 06 01;8(6):e13808.
    PMID: 32478665 DOI: 10.2196/13808
    BACKGROUND: With the unprecedented growth of mobile technology, a plethora of dialysis diet apps have been developed to promote patient dietary self-management. Nevertheless, the utility of such apps remains questionable.

    OBJECTIVE: This study aimed to evaluate the content, features, and quality of commercial dialysis diet apps for adult dialysis patients.

    METHODS: This study consisted of a quantitative content analysis of commercial dialysis diet apps downloaded from Google Play and the Apple App Store available in the Asian marketplace, searched for using the following keywords in English: dialysis diet and diet for kidney disease. Free and paid apps available in English that provide nutrition information for adult dialysis patients were included. Apps that were not relevant to the dialysis diet, not meant for patient self-management, or redundant were excluded. Apps were evaluated for language medium (subscore=1), credibility (subscore=1), food database (subscore=1), valuable features (subscore=12), health-behavior theory constructs (subscore=60), and technical quality (subscore=25). The relationships among the variables of interest were determined by Pearson correlation. Stepwise multiple linear regression analysis was performed to identify the features that contribute to greater technical quality of dialysis diet apps. Statistical significance was defined as P

  20. Fulltext Metabolic Profile of Scytalidium parasiticum-Ganoderma boninense Co-Cultures Revealed the Alkaloids, Flavonoids and Fatty Acids that Contribute to Anti-Ganoderma Activity
    Ahmad R, Lim CK, Marzuki NF, Goh YK, Azizan KA, Goh YK, et al.
    Molecules, 2020 Dec 16;25(24).
    PMID: 33339375 DOI: 10.3390/molecules25245965
    In solving the issue of basal stem rot diseases caused by Ganoderma, an investigation of Scytalidium parasiticum as a biological control agent that suppresses Ganoderma infection has gained our interest, as it is more environmentally friendly. Recently, the fungal co-cultivation has emerged as a promising method to discover novel antimicrobial metabolites. In this study, an established technique of co-culturing Scytalidium parasiticum and Ganoderma boninense was applied to produce and induce metabolites that have antifungal activity against G. boninense. The crude extract from the co-culture media was applied to a High Performance Liquid Chromatography (HPLC) preparative column to isolate the bioactive compounds, which were tested against G. boninense. The fractions that showed inhibition against G. boninense were sent for a Liquid Chromatography-Time of Flight-Mass Spectrometry (LC-TOF-MS) analysis to further identify the compounds that were responsible for the microbicidal activity. Interestingly, we found that eudistomin I, naringenin 7-O-beta-D-glucoside and penipanoid A, which were present in different abundances in all the active fractions, except in the control, could be the antimicrobial metabolites. In addition, the abundance of fatty acids, such as oleic acid and stearamide in the active fraction, also enhanced the antimicrobial activity. This comprehensive metabolomics study could be used as the basis for isolating biocontrol compounds to be applied in oil palm fields to combat a Ganoderma infection.
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