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  1. Angustilobine and andranginine type indole alkaloids and an uleine-secovallesamine bisindole alkaloid from Alstonia angustiloba
    Ku WF, Tan SJ, Low YY, Komiyama K, Kam TS
    Phytochemistry, 2011 Dec;72(17):2212-8.
    PMID: 21889176 DOI: 10.1016/j.phytochem.2011.08.001
    A total of 20 alkaloids were isolated from the leaf and stem-bark extracts of Alstonia angustiloba, of which two are hitherto unknown. One is an alkaloid of the angustilobine type (angustilobine C), while the other is a bisindole alkaloid angustiphylline, derived from the union of uleine and secovallesamine moieties. The structures of these alkaloids were established using NMR and MS analysis. Angustilobine C showed moderate cytotoxicity towards KB cells.
  2. Conformational destabilization of Bacillus licheniformis α-amylase induced by lysine modification and calcium depletion
    Tan CY, Rahman RN, Kadir HA, Tayyab S
    Acta Biochim. Pol., 2011;58(3):405-12.
    PMID: 21887412
    Bacillus licheniformis α-amylase (BLA) was chemically modified using 100-fold molar excess of succinic anhydride over protein or 0.66 M potassium cyanate to obtain 42 % succinylated and 81 % carbamylated BLAs. Size and charge homogeneity of modified preparations was established by Sephacryl S-200 HR gel chromatography and polyacrylamide gel electrophoresis. Conformational alteration in these preparations was evident by the larger Stokes radii (3.40 nm for carbamylated and 3.34 nm for succinylated BLAs) compared to 2.43 nm obtained for native BLA. Urea denaturation results using mean residue ellipticity (MRE) as a probe also showed conformational destabilization based on the early start of transition as well as ΔG(D)(H(2)O) values obtained for both modified derivatives and Ca-depleted BLA. Decrease in ΔG(D)(H(2)O) value from 5,930 cal/mol (for native BLA) to 3,957 cal/mol (for succinylated BLA), 3,336 cal/mol (for carbamylated BLA) and 3,430 cal/mol for Ca-depleted BLA suggested reduced conformational stability upon modification of amino groups of BLA or depletion of calcium. Since both succinylation and carbamylation reactions abolish the positive charge on amino groups (both α- and ε- amino), the decrease in conformational stability can be ascribed to the disruption of salt bridges present in the protein which might have released the intrinsic calcium from its binding site.
  3. Optimisation of freeze drying conditions for purified serine protease from mango (Mangifera indicaCv. Chokanan) peel
    Mehrnoush A, Tan CP, Hamed M, Aziz NA, Ling TC
    Food Chem, 2011 Sep 1;128(1):158-64.
    PMID: 25214343 DOI: 10.1016/j.foodchem.2011.03.012
    This study investigated the possible relationship between the encapsulation variables, namely serine protease content (9-50mg/ml, X1), Arabic gum (0.2-10%(w/w), X2), maltodextrin (2-5%(w/w), X3) and calcium chloride (1.3-5.5%(w/w), X4) on the enzymatic properties of encapsulated serine protease. The study demonstrated that Arabic gum, maltodextrin and calcium chloride, as coating agents, protected serine protease from activity loss during freeze-drying. The overall optimum region resulted in a suitable freeze drying condition with a yield of 92% for the encapsulated serine protease, were obtained using 29.5mg/ml serine protease content, 5.1%(w/w) Arabic gum, 3.5%(w/w) maltodextrin and 3.4%(w/w) calcium chloride. It was found that the interaction effect of Arabic gum and calcium chloride improved the serine protease activity, and Arabic gum was the most effective amongst the examined coating agents. Thus, Arabic gum should be considered as potential protection in freeze drying of serine protease.
  4. Diversity of bovine rumen methanogens In vitro in the presence of condensed tannins, as determined by sequence analysis of 16S rRNA gene library
    Tan HY, Sieo CC, Lee CM, Abdullah N, Liang JB, Ho YW
    J Microbiol, 2011 Jun;49(3):492-8.
    PMID: 21717338 DOI: 10.1007/s12275-011-0319-7
    Molecular diversity of rumen archaeal populations from bovine rumen fluid incubated with or without condensed tannins was investigated using 16S rRNA gene libraries. The predominant order of rumen archaea in the 16S rRNA gene libraries of the control and condensed tannins treatment was found to belong to a novel group of rumen archaea that is distantly related to the order Thermoplasmatales, with 59.5% (15 phylotypes) and 81.43% (21 phylotypes) of the total clones from the control and treatment clone libraries, respectively. The 16S rRNA gene library of the control was found to have higher proportions of methanogens from the orders Methanomicrobiales (32%) and Methanobacteriales (8.5%) as compared to those found in the condensed tannins treatment clone library in both orders (16.88% and 1.68% respectively). The phylotype distributed in the order Methanosarcinales was only found in the control clone library. The study indicated that condensed tannins could alter the diversity of bovine rumen methanogens.
  5. Fulltext Plasmodium knowlesi reinfection in human
    Lau YL, Tan LH, Chin LC, Fong MY, Noraishah MA, Rohela M
    Emerg Infect Dis, 2011 Jul;17(7):1314-5.
    PMID: 21762601 DOI: 10.3201/eid1707.101295
  6. Association of ABCB1 gene polymorphisms and their haplotypes with response to antiepileptic drugs: a systematic review and meta-analysis
    Haerian BS, Lim KS, Tan CT, Raymond AA, Mohamed Z
    Pharmacogenomics, 2011 May;12(5):713-25.
    PMID: 21391884 DOI: 10.2217/pgs.10.212
    Several studies demonstrated a link between ABCB1 gene variants and the response to treatment in epilepsy, but the results have been inconclusive. Here, we performed the first haplotype meta-analysis to examine the association of haplotypes of ABCB1 common variants with the response to treatment in epilepsy.
  7. Fulltext Evidence for a higher number of species of Odontotermes (Isoptera) than currently known from Peninsular Malaysia from mitochondrial DNA phylogenies
    Cheng S, Kirton LG, Panandam JM, Siraj SS, Ng KK, Tan SG
    PLoS One, 2011;6(6):e20992.
    PMID: 21687629 DOI: 10.1371/journal.pone.0020992
    Termites of the genus Odontotermes are important decomposers in the Old World tropics and are sometimes important pests of crops, timber and trees. The species within the genus often have overlapping size ranges and are difficult to differentiate based on morphology. As a result, the taxonomy of Odontotermes in Peninsular Malaysia has not been adequately worked out. In this study, we examined the phylogeny of 40 samples of Odontotermes from Peninsular Malaysia using two mitochondrial DNA regions, that is, the 16S ribosomal RNA and cytochrome oxidase subunit I genes, to aid in elucidating the number of species in the peninsula. Phylogenies were reconstructed from the individual gene and combined gene data sets using parsimony and likelihood criteria. The phylogenies supported the presence of up to eleven species in Peninsular Malaysia, which were identified as O. escherichi, O. hainanensis, O. javanicus, O. longignathus, O. malaccensis, O. oblongatus, O. paraoblongatus, O. sarawakensis, and three possibly new species. Additionally, some of our taxa are thought to comprise a complex of two or more species. The number of species found in this study using DNA methods was more than the initial nine species thought to occur in Peninsular Malaysia. The support values for the clades and morphology of the soldiers provided further evidence for the existence of eleven or more species. Higher resolution genetic markers such as microsatellites would be required to confirm the presence of cryptic species in some taxa.
  8. Fulltext Cyclic Tetrapyrrolic Photosensitisers from the leaves of Phaeanthus ophthalmicus
    Tan PJ, Ong CY, Danial A, Yusof HM, Neoh BK, Lee HB
    Chem Cent J, 2011;5:32.
    PMID: 21682931 DOI: 10.1186/1752-153X-5-32
    Twenty-seven extracts from 26 plants were identified as photo-cytotoxic in the course of our bioassay guided screening program for photosensitisers from 128 extracts prepared from 64 terrestrial plants in two different collection sites in Malaysia - Royal Belum Forest Reserve in the State of Perak and Gunung Nuang in the State of Selangor. One of the photo-cytotoxic extracts from the leaves of Phaeanthus ophtalmicus was further investigated.
  9. Combined use of wild-type HBV precore and high serum iron marker as a potential tool for the prediction of cirrhosis in chronic hepatitis B infection
    Chook JB, Ngeow YF, Yap SF, Tan TC, Mohamed R
    J Med Virol, 2011 Apr;83(4):594-601.
    PMID: 21328372 DOI: 10.1002/jmv.22016
    Hepatitis B virus (HBV) and high liver iron deposits have both been associated with the development of cirrhosis. Among HBV factors, genotype and mutations in the basal core promoter (BCP) and precore regions have been most frequently studied but the evidence for a positive association with cirrhosis has been inconsistent. In this study, sera from persons with chronic HBV infection with and without cirrhosis were used for whole HBV genome analysis and for the estimation of serum iron marker (serum iron or ferritin) levels. Single codon analysis showed that the precore wild-type, TGG (nt 1,895-1,897), gave the highest accuracy (77.5%) for the identification of cirrhosis compared to other codons. When TGG was analyzed together with the precore start codon wild-type, ATG (nt 1,814-1,816), the accuracy was improved to 80.0% (odds ratio=35.29; 95% confidence interval=3.87-321.93; Phi=0.629; P<0.001). When the serum iron marker was included for analysis, it was clear that a combination of a precore wild-type and high serum iron marker gave a better accuracy (90.0%) (odds ratio=107.67; 95% confidence interval=10.21-1,135.59; Phi=0.804; P<0.001) for the identification of cirrhosis than either biomarker alone. It appeared that a combined use of both these biomarkers might help to predict the development of cirrhosis in a person with chronic HBV infection, but longitudinal studies are required to test this hypothesis.
  10. Fulltext Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia
    Chew YL, Chan EW, Tan PL, Lim YY, Stanslas J, Goh JK
    BMC Complement Altern Med, 2011;11:12.
    PMID: 21306653 DOI: 10.1186/1472-6882-11-12
    Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family.
  11. Effect of membrane sweeping on cervical length by transvaginal ultrasonography and impact of cervical shortening on cesarean delivery
    Tan PC, Khine PP, Sabdin NH, Vallikkannu N, Sulaiman S
    J Ultrasound Med, 2011 Feb;30(2):227-33.
    PMID: 21266561
    OBJECTIVES: The purpose of this study was to evaluate cervical length changes after membrane sweeping and the effect of cervical shortening on pregnancy outcomes.

    METHODS: Low-risk women at 40 weeks' gestation undergoing membrane sweeping to expedite labor were recruited. Participants were scheduled for labor induction at 41 weeks' gestation. Transvaginal ultrasonography was performed immediately before and after membrane sweeping to measure the cervical length. Three presweep and postsweep cervical lengths were measured. The shortest lengths before and after the sweep were taken as the representative lengths. The effect of membrane sweeping on cervical length was analyzed. Multivariable logistic regression analysis was performed to evaluate the effect of cervical shortening on labor induction and the mode of delivery.

    RESULTS: For the 160 participants, the mean presweep cervical length ± SD was 21.0 ± 10.0 mm; the postsweep length was 23.8 ± 10.9 mm, an average increase of 2.8 ± 0.6 mm (P < .001). Cervical shortening after membrane sweeping was noted in 53 of 160 cases (33%). Cervical shortening was associated with a reduction in all-cause cesarean delivery but not labor induction on bivariate analysis. After adjustment for maternal age, parity, presweep Bishop score, postsweep cervical length, oxytocin augmentation, epidural analgesia, and meconium-stained fluid, cervical shortening after membrane sweeping was independently predictive of a reduction in cesarean deliveries (adjusted odds ratio, 0.24; 95% confidence interval, 0.06-0.90; P = .034).

    CONCLUSIONS: Membrane sweeping was associated with lengthening of the cervix. A shortened cervix after sweeping was independently predictive of vaginal delivery.

  12. Epidemiology and control of chikungunya fever in Singapore
    Ho K, Ang LW, Tan BH, Tang CS, Ooi PL, James L, et al.
    J Infect, 2011 Apr;62(4):263-70.
    PMID: 21315108 DOI: 10.1016/j.jinf.2011.02.001
    OBJECTIVES: We conducted an epidemiological review of the chikungunya fever situation in Singapore and described the measures taken to prevent the chikungunya virus from becoming entrenched in the tropical city-state.
    METHODS: All laboratory-confirmed cases and outbreak investigation reports maintained by the Communicable Diseases Division, Ministry of Health, and Aedes mosquito surveillance data obtained by the National Environment Agency during the period 2006 and 2009 were reviewed and analysed.
    RESULTS: Sporadic cases were imported into Singapore until the first local transmission occurred in an urban area where Aedes aegypti was the predominant vector. Subsequent introduction of a mutant viral strain (A226V) in early 2008 resulted in the rapid spread to suburban and rural areas where Aedes albopictus was the primary vector. 1072 cases including 812 (75.7%) indigenous cases were reported. The main sources of importation were India and Malaysia. Foreign contract workers were identified as high-risk for indigenous infections.
    CONCLUSIONS: The disease was successfully brought under control through aggressive vector control measures directed at A. albopictus. Although the incidence has sharply declined since January 2009, a high degree of vigilance is maintained to prevent a recurrence of epidemic transmission which can occur even with a well-established nationwide mosquito control programme.
  13. Movement disorder in a patient with stroke
    Tai ML, Tan CT, Ramli N, Begum RJ, Lim SY
    J Clin Neurosci, 2011 Feb;18(2):263, 305.
    PMID: 21294301
  14. Laparoscopic localization and microlaparotomy for focal isolated perforation in necrotizing enterocolitis: an alternative approach to a challenging problem
    Nah SA, Tan HL, Tamba RP, Aziz DA, Azzam N
    J Pediatr Surg, 2011 Feb;46(2):424-7.
    PMID: 21292104 DOI: 10.1016/j.jpedsurg.2010.11.045
    Necrotizing enterocolitis has a wide clinical spectrum of manifestation. We report a novel method of managing focal isolated perforation in necrotizing enterocolitis by using diagnostic laparoscopy to localize the site of perforation and by making a microincision over the perforation to perform exteriorization or limited resection and primary anastomosis.
  15. Fulltext Analysis of Entamoeba histolytica excretory-secretory antigen and identification of a new potential diagnostic marker
    Wong WK, Tan ZN, Othman N, Lim BH, Mohamed Z, Olivos Garcia A, et al.
    Clin Vaccine Immunol, 2011 Nov;18(11):1913-7.
    PMID: 21918120 DOI: 10.1128/CVI.05356-11
    Serodiagnosis of amoebiasis remains the preferred method for diagnosis of amoebic liver abscess (ALA). However, the commercially available kits are problematic in areas of endemicity due to the persistently high background antibody titers. Human serum samples (n = 38) from patients with ALA who live in areas of endemicity were collected from Hospital Universiti Sains Malaysia during the period of 2008 to 2010. Western blots using excretory-secretory antigen (ESA) collected from axenically grown Entamoeba histolytica were probed with the above serum samples. Seven antigenic proteins of ESA with various reactivities were identified, i.e., 152 kDa, 131 kDa, 123 kDa, 110 kDa, 100 kDa, 82 kDa, and 76 kDa. However, only the 152-kDa and 110-kDa proteins showed sensitivities above 80% in the Western blot analysis. All the antigenic proteins showed undetectable cross-reactivity when probed with healthy human serum samples (n = 30) and serum samples from other infections (n = 33). From the matrix-assisted laser desorption ionization-two-stage time of flight (MALDI-TOF/TOF) analysis, the proteins were identified as heavy subunits of E. histolytica lectin and E. histolytica pyruvate phosphate dikinase, respectively. Use of the E. histolytica lectin for diagnosis of ALA has been well reported by researchers and is being used in commercialized kits. However, this is the first report on the potential use of pyruvate phosphate dikinase for diagnosis of ALA; thus, this molecule merits further evaluation on its diagnostic value using a larger panel of serum samples.
  16. Validity and reliability of the Malay-language translation of the Rome III Diagnostic Questionnaire for irritable bowel syndrome
    Lee YY, Waid A, Tan HJ, Chua SB, Whitehead WE
    J Gastroenterol Hepatol, 2012 Apr;27(4):746-50.
    PMID: 22004172 DOI: 10.1111/j.1440-1746.2011.06943.x
    The Malay language is widely used within the "Malay Archipelago" particularly in Malaysia, Indonesia, Philippines, Singapore and Brunei with a combined population of 300 million. There are no reliable data on the epidemiology of irritable bowel syndrome (IBS) in the Malay speaking population because the Rome Diagnostic Questionnaire has not been translated and validated for the Malay language. The current study aimed to translate and validate the Rome III IBS Diagnostic Questionnaire, Red Flag and Psychosocial Alarm questionnaires into the Malay language.
  17. Molecular identification of house dust mites and storage mites
    Wong SF, Chong AL, Mak JW, Tan J, Ling SJ, Ho TM
    Exp Appl Acarol, 2011 Oct;55(2):123-33.
    PMID: 21468750 DOI: 10.1007/s10493-011-9460-6
    Mites are known causes of allergic diseases. Currently, identification of mites based on morphology is difficult if only one mite is isolated from a (dust) sample, or when only one gender is found, or when the specimen is not intact especially with the loss of the legs. The purpose of this study was to use polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the ITS2 gene, to complement the morphological data for the identification of mites to the species level. For this, six species were cultured: Dermatophagoides pteronyssinus, D. farinae, Blomia tropicalis, Tyrophagus putrescentiae, Aleuroglyphus ovatus and Glycycometus malaysiensis. Genomic DNA of the mites was extracted, quantified, amplified and digested individually with restriction enzymes. Hinf I and Ple I differentiated the restriction patterns of D. pteronyssinus and D. farinae. Bfa I and Alu I enzymes differentiated B. tropicalis and G. malaysiensis. Ple I enzyme was useful for the differentiation between T. putrescentiae and A. ovatus. Bfa I was useful for the differentiation of G. malaysiensis from the rest of the species. In conclusion, different species of mites can be differentiated using PCR-RFLP of ITS2 region. With the established PCR-RFLP method in this study, identification of these mites to the species level is possible even if complete and intact adult specimens of both sexes are not available. As no study to date has reported PCR-RFLP method for the identification of domestic mites, the established method should be validated for the identification of other species of mites that were not included in this study.
  18. Thickened carotid intima media thickness and carotid atherosclerosis among lupus nephritis patients: the role of traditional and lupus-specific factors
    Sazliyana S, Mohd Shahrir MS, Kong NC, Tan HJ, Hamidon BB, Azmi MT
    Int J Rheum Dis, 2011 Aug;14(3):267-75.
    PMID: 21816023 DOI: 10.1111/j.1756-185X.2011.01638.x
    AIM: The objectives of this study were to investigate the frequency of thickened carotid intima media thickness (CIMT) and atherosclerosis among lupus nephritis (LN) patients and to study their associated risk factors.
    METHOD: In this cross-sectional study, carotid ultrasonography was performed on consecutive LN patients to determine CIMT and presence of carotid plaques. CIMT was considered to be abnormally thickened if it was more than the 75th percentile matched for age and sex from the 'Carotid Atherosclerosis Progression Study'. The association between thickened CIMT with traditional cardiovascular risk factors and lupus characteristics were examined. A total of 83 patients with the mean age of 33.6 ± 10 years were recruited.
    RESULTS: Fourteen patients (16.9%) had thickened CIMT and three (3.6%) had carotid plaques. On univariate analysis, traditional risk factors significantly associated with thickened CIMT (P < 0.05) were patient's current age, diabetes mellitus and waist circumference. Meanwhile, a lower serum C4 levels and higher serum C-reactive protein levels were the lupus-specific factors associated with thickened CIMT (P < 0.05, P < 0.05 and P < 0.01, respectively). In logistic regression analysis, the independent predictors of thickened CIMT were age of diagnosis, lower serum C4 levels and waist circumference (P < 0.05).
    CONCLUSION: More lupus specific factors were independently associated with thickened CIMT, suggesting that a multi-targeted approach of treatment addressing both the lupus and traditional cardiovascular risks are very important. Larger prospective studies of these special risk factors are indicated.
  19. Impact of interventional nephrology on outcome and penetration rate of a CAPD program
    Wong CM, Ng KP, Keng TC, Lim SK, Tan SY
    Perit Dial Int, 2011 3 24;31(2):194-6.
    PMID: 21427247 DOI: 10.3747/pdi.2009.00237
  20. Fulltext Complete killing of Caenorhabditis elegans by Burkholderia pseudomallei is dependent on prolonged direct association with the viable pathogen
    Lee SH, Ooi SK, Mahadi NM, Tan MW, Nathan S
    PLoS One, 2011;6(3):e16707.
    PMID: 21408228 DOI: 10.1371/journal.pone.0016707
    Burkholderia pseudomallei is the causative agent of melioidosis, a disease of significant morbidity and mortality in both human and animals in endemic areas. Much remains to be known about the contributions of genotypic variations within the bacteria and the host, and environmental factors that lead to the manifestation of the clinical symptoms of melioidosis.
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