Displaying publications 21 - 40 of 58 in total

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  1. Development of a simultaneous liquid-liquid extraction and chiral derivatization method for stereospecific GC-MS analysis of amphetamine-type stimulants in human urine using fractional factorial design
    Aasim WR, Gan SH, Tan SC
    Biomed Chromatogr, 2008 Sep;22(9):1035-42.
    PMID: 18655218 DOI: 10.1002/bmc.1073
    A stereospecific gas chromatography-mass spectrometry analysis method for amphetamine-type stimulants in human urine was recently developed. For maximum efficiency, liquid-liquid extraction and chiral derivatization of the analytes using (R)-(-)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetyl chloride were performed simultaneously. The effects of (1) use of saturated sodium chloride in 2.0 M sodium hydroxide, (2) extraction solvent volume, (3) percentage of triethylamine, (4) derivatization reagent volume, (5) sample mixing time, (6) incubation temperature and (7) incubation time on method sensitivity and variability were assessed using a two-level, eight-run Plackett-Burman design followed by a fold-over design. The use of saturated sodium chloride solution and the derivatization reagent volume were significant factors (ANOVA, p<0.01). The saturated sodium chloride solution decreased sensitivity whereas an increased volume of derivatization reagent increased sensitivity. Calibration curves for all analytes were linear between 5 and 500 microg/L, with correlation coefficients of >0.99. Detection limits were
  2. Adhesion of Pseudomonas fluorescens biofilms to glass, stainless steel and cellulose
    Wan Dagang WR, Bowen J, O'Keeffe J, Robbins PT, Zhang Z
    Biotechnol Lett, 2016 May;38(5):787-92.
    PMID: 26892223 DOI: 10.1007/s10529-016-2047-x
    The adhesion of colloidal probes of stainless steel, glass and cellulose to Pseudomonas fluorescens biofilms was examined using atomic force microscopy (AFM) to allow comparisons between surfaces to which biofilms might adhere.
  3. Fulltext Dengue haemorrhagic fever: a risk of returning home
    Jacobs MG, Brook MG, Weir WR, Bannister BA
    BMJ, 1991 Apr 06;302(6780):828-9.
    PMID: 2025706
  4. Interaction of Malaysian sera with Plasmodium vivax sporozoite antigen
    Lee M, Davis DR, Ballou WR, Folena-Wasserman G, Lewis GE
    Am J Trop Med Hyg, 1988 Dec;39(6):535-9.
    PMID: 3061309
    A seroepidemiologic survey of Plasmodium vivax and Plasmodium falciparum transmission was conducted in 94 Orang Asli children and adults. The prevalence of malaria was 46% in this population, and infections due to P. vivax and P. falciparum occurred with equal frequency. Multi-species infection was common, particularly in children less than 10 years of age. Circumsporozoite (CS) antibodies to P. vivax were detected by ELISA, using the recombinant protein NS181V20, in sera from 53-95% of all subjects in this study. The specificity of reactivity to NS181V20 was confirmed by immunofluorescence using air-dried sporozoites. CS antibodies to P. falciparum were present in less than 50% of the population less than 30 years of age. These data support further testing of this protein as a candidate vivax vaccine.
  5. A polyol-stevia blended sugar replacer exhibits low glycemic response among human subjects
    Ng AWR, Loh KK, Gupta N, Narayanan K
    Clin Nutr ESPEN, 2019 10;33:39-41.
    PMID: 31451273 DOI: 10.1016/j.clnesp.2019.07.014
    BACKGROUND & AIMS: Consumption of sugars in food and beverages has increased at an alarming rate. While excessive daily sugar intake has been well-associated as the onset of medical complications, additional sugars are still used in manufactured food products just to satisfy the consumers' needs. Hence, there is a need to develop sugar replacers that have low glycemic response without compromising the organoleptic characteristics of food products. This study aimed to determine if SUITENA™, a novel sweetener containing erythritol, xylitol, and Stevia, has low glycemic response upon consumption by human subjects.

    METHODS: Six human subjects were randomly chosen and were healthy at the point of experimentation. Capillary blood was collected via finger-prick method to monitor the glycemic response of every individual for 90 min after ingestion of sugar solution.

    RESULTS: It was found that the mean area under the curve (AUC) of the dextrose standard was 11.8-fold higher (p 

  6. Gas chromatographic determination of eugenol in ethanol extract of cloves
    Myint S, Daud WR, Mohamad AB, Kadhum AA
    J Chromatogr B Biomed Appl, 1996 Apr 26;679(1-2):193-5.
    PMID: 8998560
    An ethanolic extract of cloves was analyzed by gas chromatography directly to identify eugenol and other major phenolic compounds without previous separation of other components. Separation was performed on a fused-silica capillary column of 30 m x 0.53 mm I.D., 0.53 microns film thickness. The detector was a flame ionization detector. Helium gas at a flow-rate of 3 ml/min was used as a carrier gas. The analysis were performed with linear temperature programming. Nine components were detected and special attention was given to the major phenolic compound, eugenol.
  7. Anti-malarial and cytokine-modulating effects of andrographolide in a murine model of malarial infection
    Hassan WRM, Basir R, Ali AH, Embi N, Sidek HM
    Trop Biomed, 2019 Sep 01;36(3):776-791.
    PMID: 33597499
    Malarial pathogenesis involves among others, uncontrolled or excessive cytokine production arising from dysregulated immune responses mounted by the host to eliminate the plasmodial parasite. The ubiquitous serine/threonine kinase, glycogen synthase kinase3β (GSK3β) is a crucial regulator of the balance between pro- and anti-inflammatory cytokine productions in the inflammatory response to pathogenic infections. Andrographolide, a bioactive compound in Andrographis paniculata, displays GSK3- inhibitory effects. A previous study elsewhere has shown that this compound has antimalarial activity but the molecular basis of its action is yet to be elucidated. Here we aimed to study the anti-malarial activity of andrographolide in a murine model of malarial infection to investigate whether its mechanism of action involves cytokine modulation and inhibition of GSK3β. Andrographolide showed strong and selective anti-plasmodial activity (IC50 = 13.70±0.71 µM; SI = 30.43) when tested against cultures of P. falciparum 3D7. Intraperitoneal administration of andrographolide (5 mg/kg body weight (bw)) into P. berghei NK65-infected ICR mice resulted in chemo-suppression of 60.17±2.12%, and significantly (P<0.05) improved median survival time of infected mice compared to nontreated control. In addition, andrographolide treatment significantly (P<0.05) decreased the level of serum pro-inflammatory cytokine, IFN-γ (1.4-fold) whilst the anti-inflammatory cytokines, IL-10 and IL-4 were increased 2.3- and 2.6-fold respectively. Western blot analyses revealed that andrographolide treatment of P. berghei NK65-infected mice resulted in an increased level of phosphorylated GSK3β (Ser9) in liver of infected mice. Andrographolide administration also decreased the levels of phosphorylated NF-κB p65 (Ser536) and phosphorylated Akt (Ser473) in liver of malaria- infected animals. Taken together, our findings demonstrate that the cytokine-modulating effect of andrographolide in experimental malarial infection involves at least in part inhibition of NF-κB activation as a consequence of GSK3β inhibition. Based on its cytokine-modulating effects, andrographolide is thus a plausible candidate for adjunctive therapy in malaria subject to clinical evaluations.
  8. Fulltext Vegetation-edaphic correlation and importance value index in himalayan 'ecotone' temperate conifer forest using the multivariate technique
    Ali F, Zeb M, Amin M, Rajpar MN, Hidayat S, Khan WR
    Saudi J Biol Sci, 2024 May;31(5):103983.
    PMID: 38590389 DOI: 10.1016/j.sjbs.2024.103983
    Himalayan 'Ecotone' temperate conifer forest is the cradle of life for human survival and wildlife existence. In spite of the importance of these areas, they have not been studied in depth. This study aimed to quantify the floristic structure, important value index (IVI), topographic and edaphic variables between 2019 and 2020 utilizing circular quadrant method (10 m x 10 m). The upper-storey layer consisted of 17 tree species belongs to 12 families and 9 orders. Middle-storey shrubs comprised of 23 species representing 14 families and 12 orders. A total of 43 species of herbs, grasses, and ferns were identified from the ground-storey layer, representing 25 families and 21 orders. Upper-storey vegetation structure was dominated by Pinus roxburghii (22.45 %) and middle-storey by Dodonaea viscosa (7.69 %). However, the ground layer vegetation was diverse in species composition (43 species) and distribution. The floral vegetation structure was encompassing of three floral communities which were diverse in IVI, such as, in Piro-Aial (Group 2), Pinus roxburghii (54.46 x 15.94) had the highest IVI value, followed by Pinus wallichiana (45.21 x 14.85) in Piwa-Quin (Group 3) and Ailanthus altissima (22.84 x 19.25) in Aial-Qugal (Group 1). However, the IVI values for Aesculus indica, Celtis australis, and Quercus incana in Aial-Qugal (Group 1) were not determined due to low detection rate. Nevertheless, eleven of these species showed 0 IVI values in Piro-Aial (Group 2) and Piwa-Quin (Group 3). CCA ordination biplot illustrated the significant differences among floral communities and its distribution, which impacted by temperature, rainfall, soil pH, altitude, and topographic features. Ward's agglomerative clustering finding reflected 'Ecotone' temperate conifer forest is rich and diverse floristic structure.
  9. Polymorphism of ITPA 94C>A and risk of adverse effects among patients with acute lymphoblastic leukaemia treated with 6-mercaptopurine
    Wan Rosalina WR, Teh LK, Mohamad N, Nasir A, Yusoff R, Baba AA, et al.
    J Clin Pharm Ther, 2012 Apr;37(2):237-41.
    PMID: 21545474 DOI: 10.1111/j.1365-2710.2011.01272.x
    Genetic polymorphisms of thiopurine S-methyltransferase (TPMT) and inosine triphosphate pyrophosphohydrolase (ITPA 94C>A) contribute to variable responses, including fatal adverse effects, among subjects treated with 6-mercaptopurine (6-MP). Our objectives were to investigate the distribution of specific TPMT and ITPA genotypes in healthy subjects and patients with acute lymphoblastic leukaemia (ALL) from the three main ethnic groups (Malays, Chinese and Indians) in Malaysia and the association of the polymorphisms with adverse effects of 6-MP.
  10. A novel agricultural waste adsorbent for the removal of lead (II) ions from aqueous solutions
    Ibrahim MN, Ngah WS, Norliyana MS, Daud WR, Rafatullah M, Sulaiman O, et al.
    J Hazard Mater, 2010 Oct 15;182(1-3):377-85.
    PMID: 20619537 DOI: 10.1016/j.jhazmat.2010.06.044
    The present study explores the ability of modified soda lignin (MSL) extracted from oil palm empty fruit bunches (EFB) in removing lead (II) ions from aqueous solutions. The effect of contact time, point zero charge (pH(pzc)) and pH of the solution, initial metal ion concentration and adsorbent dosage on the removal process were investigated. Furthermore, the MSL is characterized by SEM, XRF, FT-IR and surface area analysis. Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The kinetic data obtained at different initial concentrations were analyzed using pseudo-first-order and pseudo-second-order models. The results provide strong evidence to support the hypothesis of adsorption mechanism.
  11. Efficacy of phototherapy for neonatal jaundice is increased by the use of low-cost white reflecting curtains
    Djokomuljanto S, Quah BS, Surini Y, Noraida R, Ismail NZ, Hansen TW, et al.
    Arch. Dis. Child. Fetal Neonatal Ed., 2006 Nov;91(6):F439-42.
    PMID: 16877479
    To determine whether the addition of low-cost reflecting curtains to a standard phototherapy unit could increase effectiveness of phototherapy for neonatal jaundice.
  12. Requirement for specific gravity and creatinine adjustments for urinary steroids and luteinizing hormone concentrations in adolescents
    Singh GK, Balzer BW, Desai R, Jimenez M, Steinbeck KS, Handelsman DJ
    Ann. Clin. Biochem., 2015 Nov;52(Pt 6):665-71.
    PMID: 25780247 DOI: 10.1177/0004563215580385
    Urinary hormone concentrations are often adjusted to correct for hydration status. We aimed to determine whether first morning void urine hormones in growing adolescents require adjustments and, if so, whether urinary creatinine or specific gravity are better adjustments.
  13. Trichosporon Asahii fungaemia in an immunocompetent polytrauma patient who received multiple antibiotics
    Ding CH, Khaithir TMN, Wahab AA, Faiz MA, Saarah WR
    Malays J Pathol, 2020 Aug;42(2):293-296.
    PMID: 32860385
    Trichosporon asahii is a yeast-like fungus that is emerging as an important cause of invasive infections in tertiary medical centres. A 58-year-old Chinese man with no known medical illnesses presented with liver lacerations and multiple fractures following an alleged 12-foot fall at a construction site. The gravity of his injuries and poor haemodynamic status necessitated an intensive care unit (ICU) admission, during which several febrile episodes were detected and multiple antibiotics were administered. After being in the ICU for at least two weeks, a urease-positive yeast was isolated from the patient's blood. The yeast formed dry, fuzzy and wrinkled white colonies on Sabouraud dextrose agar following prolonged incubation, and produced blastoconidia, true hyphae, pseudohyphae and arthroconidia on slide culture. It was identified biochemically by the ID 32 C kit as T. asahii. The yeast had elevated minimal inhibitory concentration (MIC) values to fluconazole, amphotericin B, flucytosine and all echinocandins tested. In view of this, the patient was treated with voriconazole and was successfully transferred to the general medical ward.
  14. Cellulitis due to Shewanella algae: Crucial diagnostic clues from basic microbiological tests
    Ding CH, Wahab AA, Muttaqillah NAS, Kamarudin N, Saarah WR
    Trop Biomed, 2019 Dec 01;36(4):883-887.
    PMID: 33597461
    Shewanella spp. are infrequently implicated in human infections but they are emerging pathogens with particular significance in regions with warm climates, such as Southeast Asia. This is a case of a middle-aged diabetic and hypertensive man who presented with worsening congestive heart failure symptoms associated with fever and a painful right leg. His right leg had numerous scabs and was tender, warm and erythematous. He was provisionally diagnosed with decompensated heart failure precipitated by cellulitis and uncontrolled hypertension. His blood grew non-fermentative, oxidase-positive and motile gram-negative bacilli which produced hydrogen sulfide on triple sugar iron agar. When cultured on blood agar, mucoid and weakly β-haemolytic colonies were observed after 48 hours. API 20 NE named the isolate as Shewanella putrefaciens but 16S rRNA sequence analysis identified the organism as Shewanella algae. The patient was treated with a 10-day course of ceftazidime, which resulted in the resolution of the cellulitis.
  15. Numerical analysis of flow distribution behavior in a proton exchange membrane fuel cell
    Lim BH, Majlan EH, Daud WRW, Rosli MI, Husaini T
    Heliyon, 2018 Oct;4(10):e00845.
    PMID: 30338304 DOI: 10.1016/j.heliyon.2018.e00845
    The flow distribution of a proton exchange membrane fuel cell within a manifold plays an important role on its performance. This study presents a numerical analysis of the flow distribution behavior within different manifold configurations. A two-dimensional model with 75 cells was employed to study the flow behavior. The variation in the stoichiometry and number of cells was also studied. Three different flow configurations were considered with different numbers of flow inlets and outlets. The flow characteristics, such as the pressure and velocity variations in the manifold and cells, were measured to determine the effects of the different flow configurations. The results indicated that the double inlet/outlet configuration had the best flow distribution when using 75 cells. Moreover, increasing the stoichiometry resulted in a better flow distribution to the cells in a stack.
  16. The differential metabolite profiles of acute lymphoblastic leukaemic patients treated with 6-mercaptopurine using untargeted metabolomics approach
    Bannur Z, Teh LK, Hennesy T, Rosli WR, Mohamad N, Nasir A, et al.
    Clin Biochem, 2014 Apr;47(6):427-31.
    PMID: 24582698 DOI: 10.1016/j.clinbiochem.2014.02.013
    Acute lymphoblastic leukaemia (ALL) has posed challenges to the clinician due to variable patients' responses and late diagnosis. With the advance in metabolomics, early detection and personalised treatment are possible.
  17. The significance of amelogenin loci from toothpicks as forensic evidence for sex determination
    Kurniawan A, Rizky BN, Chusida A, Prakoeswa BFWR, Athalia SA, Malau STJ, et al.
    J Taibah Univ Med Sci, 2023 Feb;18(1):148-153.
    PMID: 36398010 DOI: 10.1016/j.jtumed.2022.07.010
    Objective: DNA analysis has become the gold standard of all identification methods in forensic science. There are several primary and secondary sources of DNA samples in the field of forensics. Primary sources can be obtained directly from individuals, whereas secondary sources of DNA samples include items used by someone such as clothes, toothbrushes, and toothpicks. In Asian countries such as Korea, Japan, and Indonesia, toothpicks are often used, as the tip of toothpicks used to clear food particles in the interdental regions can be utilized to capture DNA samples from saliva. The use of saliva samples for DNA analysis in sex identification is based on short tandem repeats with the amelogenin (AMG) locus. The purpose of this study was to examine the concentration and purity of DNA on toothpicks as evidence in criminal case investigations, as well as its potential as sex determination material.

    Methods: Eight subjects were instructed to clean the interproximal side of their posterior teeth using a toothpick. Each toothpick sample was kept for 0 days (as a control), 14 days, and 20 days. The purity and DNA concentration of each sample were determined through DNA examination. After determining the concentration and purity of DNA from each sample, electrophoresis of the AMG loci was performed for sex determination.

    Results: This study showed that the average concentration of DNA on toothpicks ranged from 425.25 to 796.25 μg/ml, and the average purity of DNA ranged from 1.09 to 1.13 μg/ml. The AMG gene produces 112 and 116 base pair amplicons from the X and Y chromosomes.

    Conclusion: Sex determination using DNA can be done using AMG loci, a protein found on the sex chromosomes (X and Y). The value of DNA concentration on toothpicks could be used to support forensic identification after 20 days at room temperature.

  18. Dynamic Adsorption and Oil Recovery of Nanosilica on Carbonate Rock
    Jumiati W, Permadi AK, Hendraningrat L, Siagian UWR, Sunendar B
    ACS Omega, 2024 Nov 05;9(44):44134-44153.
    PMID: 39524620 DOI: 10.1021/acsomega.4c02994
    Numerous studies have investigated the use of nanosilica particles for enhanced oil recovery (EOR). Many of these studies focused on experiments involving LHP (lipophobic and hydrophilic polysilicones) and HLP (hydrophobic and lipophilic polysilicones) in water-wet sandstones and oil-wet carbonate rocks. This paper's gap investigates comparing LHP and HLP nanosilica particles in enhancing oil recovery in water-wet and neutral-wet carbonate rocks. Additionally, the effects of LHP and HLP adsorption during injection and their influence on oil recovery have not yet been extensively investigated. This study used Sumatran crude oil from Indonesia, and to support the objectives of this study, several analyses were conducted, including measurements of rock wettability, interfacial tension, fluid stability, zeta potential, UV-vis spectrophotometric adsorption, and coreflood injection as the main experiment under different scenarios. The findings demonstrate that the oil recovery enhancement is influenced by the type of nanosilica used. Specifically, LHP nanosilica exhibited higher oil recovery in neutral-wet carbonate rocks, about 9.78-44.44%, while HLP nanosilica showed better performance in water-wet carbonate rocks in the range of 4.11-41.01% in different injection scenarios. Moreover, a directly proportional relationship was observed between the adsorption of LHP and HLP nanosilica on the rock and fluid and oil recovery, where increased adsorption corresponded to higher oil recovery for each injection scenario with the respective type of nanosilica about 0.06-0.15 mg/g. These results provide valuable insights into selecting the appropriate nanosilica and initial wettability conditions in EOR applications.
  19. Fulltext Urinary Sex Steroids and Anthropometric Markers of Puberty - A Novel Approach to Characterising Within-Person Changes of Puberty Hormones
    Singh GK, Balzer BW, Kelly PJ, Paxton K, Hawke CI, Handelsman DJ, et al.
    PLoS One, 2015;10(11):e0143555.
    PMID: 26599397 DOI: 10.1371/journal.pone.0143555
    The longitudinal relationships of within-individual hormone and anthropometric changes during puberty have not ever been fully described. The objectives of this study were to demonstrate that 3 monthly urine collection was feasible in young adolescents and to utilise liquid chromatography-tandem mass spectrometry assay methods for serum and urine testosterone (T), estradiol (E2) and luteinizing hormone (LH) in adolescents by relating temporal changes in urine and serum hormones over 12 months to standard measures of pubertal development.
  20. Mercury in dental amalgam: Are our health care workers at risk?
    Sahani M, Sulaiman NS, Tan BS, Yahya NA, Anual ZF, Mahiyuddin WR, et al.
    J Air Waste Manag Assoc, 2016 Nov;66(11):1077-1083.
    PMID: 27192328 DOI: 10.1080/10962247.2016.1188866
    Dental amalgam in fillings exposes workers to mercury. The exposure to mercury was investigated among 1871 dental health care workers. The aim of the study was to evaluate the risk of mercury exposure among dental compared to nondental health care workers and to determine other risk factors for mercury exposure. Respondents answered questionnaires to obtain demographic, personal, professional, and workplace information and were examined for their own amalgam fillings. Chronic mercury exposure was assessed through urinary mercury levels. In total, 1409 dental and 462 nondental health care workers participated in the study. Median urine mercury levels for dental and nondental health care workers were 2.75 μg/L (interquartile range [IQR] = 3.0175) and 2.66 μg/L (IQR = 3.04) respectively. For mercury exposure, there were no significant risk factor found among the workers involved within the dental care. The Mann-Whitney test showed that urine mercury levels were significantly different between respondents who eat seafood more than 5 times per week compared to those who eat it less frequently or not at all (p = 0.003). The urinary mercury levels indicated significant difference between dental workers in their practice using squeeze cloths (Mann-Whitney test, p = 0.03). Multiple logistic regression showed that only the usage of cosmetic products that might contain mercury was found to be significantly associated with the urinary mercury levels (odds ratio [OR] = 15.237; CI: 3.612-64.276). Therefore, mean urinary mercury levels of health care workers were low. Exposure to dental amalgam is not associated with high mercury exposure. However, usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.

    IMPLICATIONS: Exposure to the high levels of mercury from dental amalgam can lead to serious health effects among the dental health care workers. Nationwide chronic mercury exposure among dental personnel was assessed through urinary mercury levels. Findings suggest low urinary mercury levels of these health care workers. Exposure to dental amalgam is not associated with high mercury exposure. However, the usage of cosmetic products containing mercury and high seafood consumption may lead to the increase of exposure to mercury.
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