Displaying publications 101 - 120 of 164 in total

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  1. Cellulose nanocrystals isolated from oil palm trunk
    Lamaming J, Hashim R, Sulaiman O, Leh CP, Sugimoto T, Nordin NA
    Carbohydr Polym, 2015;127:202-8.
    PMID: 25965475 DOI: 10.1016/j.carbpol.2015.03.043
    In this study cellulose nanocrystals were isolated from oil palm trunk (Elaeis guineensis) using acid hydrolysis method. The morphology and size of the nanocrystals were characterized using scanning electron microscopy and transmission electron microscopy. The results showed that the nanocrystals isolated from raw oil palm trunk (OPT) fibers and hot water treated OPT fibers had an average diameter of 7.67 nm and 7.97 nm and length of 397.03 nm and 361.70 nm, respectively. Fourier Transform Infrared spectroscopy indicated that lignin and hemicellulose contents decreased. It seems that lignin was completely removed from the samples during chemical treatment. Thermogravimetric analysis demonstrated that cellulose nanocrystals after acid hydrolysis had higher thermal stability compared to the raw and hot water treated OPT fibers. The X-ray diffraction analysis increased crystallinity of the samples due to chemical treatment. The crystalline nature of the isolated nanocrystals from raw and hot water treated OPT ranged from 68 to 70%.
  2. Prediction of ultrasonic pulse velocity for enhanced peat bricks using adaptive neuro-fuzzy methodology
    Motamedi S, Roy C, Shamshirband S, Hashim R, Petković D, Song KI
    Ultrasonics, 2015 Aug;61:103-13.
    PMID: 25957464 DOI: 10.1016/j.ultras.2015.04.002
    Ultrasonic pulse velocity is affected by defects in material structure. This study applied soft computing techniques to predict the ultrasonic pulse velocity for various peats and cement content mixtures for several curing periods. First, this investigation constructed a process to simulate the ultrasonic pulse velocity with adaptive neuro-fuzzy inference system. Then, an ANFIS network with neurons was developed. The input and output layers consisted of four and one neurons, respectively. The four inputs were cement, peat, sand content (%) and curing period (days). The simulation results showed efficient performance of the proposed system. The ANFIS and experimental results were compared through the coefficient of determination and root-mean-square error. In conclusion, use of ANFIS network enhances prediction and generation of strength. The simulation results confirmed the effectiveness of the suggested strategies.
  3. Chaetomium globosum Cutaneous Fungal Infection Confirmed by Molecular Identification: A Case Report from Malaysia
    Mohd Tap R, Sabaratnam P, Ahmad NA, Abd Razak MF, Hashim R, Ahmad N
    Mycopathologia, 2015 Aug;180(1-2):137-41.
    PMID: 25894509 DOI: 10.1007/s11046-015-9890-5
    An 11-year-old girl presented with multiple blisters on her the right foot complicated with cellulitis. The conventional and molecular identification were performed on the culture. The internal transcribed spacer (ITS) region in rRNA gene of the isolate was amplified by PCR. The sequence of the amplified ITS region matched 99 % with that of Chaetomium globosum in the GenBank. This is the first report describing C. globosum causing cutaneous infection in Malaysia.
  4. Bioengineered silver nanoparticles capped with bovine serum albumin and its anticancer and apoptotic activity against breast, bone and intestinal colon cancer cell lines
    Majeed S, Aripin FHB, Shoeb NSB, Danish M, Ibrahim MNM, Hashim R
    Mater Sci Eng C Mater Biol Appl, 2019 Sep;102:254-263.
    PMID: 31146998 DOI: 10.1016/j.msec.2019.04.041
    The aim of the current study was to biosynthesize the silver nanoparticles (AgNPs) from the bacterial strain of Bacillus cereus (ATCC 14579) extracellularly. When bacterial extract was challenged with 1 mM silver nitrate (AgNO3) the color of the extract changed into brown confirms the formation of nanoparticles. These nanoparticles were capped with bovine serum albumin (BSA). UV- visible spectroscopy showed the absorption peak at 420 nm indicates the formation of AgNPs. Fourier Infra -red (FTIR) attenuated total reflection (ATR) spectroscopy showed amide and amine group associated with AgNPs that stabilizes the nanoparticles. Energy dispersive x-ray spectroscopy (EDX) showed a strong peak of silver confirms the presence of silver. Thermo gravimetric analysis (TGA) analysis was used to determine the protein degradation showed less protein degradation at higher temperature confirms the stability of nanoparticles. Transmission electron microscopy (TEM) showed the AgNPs are well dispersed and spherical, and 5.37 nm to 17.19 whereas albumin coated nanoparticles are size ranges from 11.26 nm to 23.85 nm. The anticancer effect of capped AgNPs (cAgNPs) showed the IC50 value against breast cancer MCF-7 at 80 μg/mL, intestinal colon cancer HCT- 116 60 μg/mL, and bone cancer osteosarcoma MG-63 cell line80 μg/mL while against normal fibroblast cells 3T3 cells showed the IC50 value at 140 μg/mL. Lactate dehydrogenase assay (LDH) showed higher toxicity on MCF-7, HCT-116, and MG-63 cells. The apoptotic study clearly showed the blebbing of membrane, chromatin condensation due to the production of reactive oxygen species (ROS) by ethidium bromide and acridine orange dual staining method. The DNA analysis showed the complete fragmentation of the DNA of treated cells when compared with control cells.
  5. Fulltext Dry Thermotropic Glycolipid Self-Assembly:A Review
    Hashim R, Zahid NI, Velayutham TS, Aripin NFK, Ogawa S, Sugimura A
    J Oleo Sci, 2018 Jun 01;67(6):651-668.
    PMID: 29760332 DOI: 10.5650/jos.ess17261
    Also recognized as carbohydrate liquid crystals, glycolipids are amphiphiles whose basic unit comprises of a sugar group attached to an alkyl chain. Glycolipids are amphitropic, which means these materials form liquid crystal self-assemblies when dry (thermotropic) as well as when dissolved in solvents (lyotropic/surfactants) such as water. Many glycolipids are also naturally derived since these can be found in cell membranes. Their membrane and surfactant functions are largely understood through their lyotropic properties. While glycolipids are expected to play major roles as eco-friendly surfactants in the global surfactant market, their usefulness as thermotropic liquid crystal material is, to date, unknown, due to relatively lack of research performed and data reported in the literature. Understandably since glycolipids are hygroscopic with many hydroxy groups, removing the last trace water is very challenging. In recent time, with careful lyophilization and more consistent characterization technique, some researchers have attempted serious studies into "dry" or anhydrous glycolipids. Motivated by possible developments of novel thermotropic applications, some results from these studies also provide surprising new understanding to support conventional wisdom of the lyotropic systems. Here we review the dry state of glycosides, a family of glycolipids whose sugar headgroup is linked to the lipid chain via a glycosidic oxygen linker. The structure property relationship of both linear and anhydrous Guerbet glycosides will be examined. In particular, how the variation of sugar stereochemistry (e.g. anomer vs. epimer), the chain length and chain branching affect the formation of thermotropic liquid crystals phases, which not only located under equilibrium but also far from equilibrium conditions (glassy phase) are scrutinized. The dry glycolipid assembly has been subjected to electric and magnetic fields and the results show interesting behaviors including a possible transient current generation.
  6. Reinforced lignin-phenol-glyoxal (LPG) wood adhesives from coconut husk
    Aziz NA, Latip AFA, Peng LC, Latif NHA, Brosse N, Hashim R, et al.
    Int J Biol Macromol, 2019 Dec 01;141:185-196.
    PMID: 31479667 DOI: 10.1016/j.ijbiomac.2019.08.255
    Lignin was extracted from coconut husk via alkaline pulping, either Kraft or soda. The isolated lignin samples were classified as hydroxy-benzaldehyde, vanillin, and syringaldehyde type according to Fourier-transform Infrared Spectroscopy, 1H and 13C Nuclear Magnetic Resonance (NMR) spectra. Soda lignin (SL) showed higher thermal stability and glass transition temperature (Tg) than Kraft lignin (KL) as proven by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), respectively. The soda-lignin-phenol-glyoxal (SLPG) resins with the optimum percentage of lignin substitution at 30% showed improved solid content and gel time in comparison to 30% of Kraft-lignin-phenol-glyoxal (KLPG) and phenol-glyoxal (PG) resin. The good mechanical properties in SLPG is due to the higher amount of molecular weight as well as higher phenolic and G-type unit in lignin that improve the properties of 30% SLPG adhesive. Moreover, the addition of layered double hydroxides (LDH) as reinforced filler up to 15%-30% SLPG adhesive blend shows a great performance (especially mechanical properties) as compared to 30% SLPG adhesive alone.
  7. Fulltext Pneumococcal serotype distribution and antibiotic susceptibility in Malaysia: A four-year study (2014-2017) on invasive paediatric isolates
    Arushothy R, Ahmad N, Amran F, Hashim R, Samsudin N, Azih CRC
    Int J Infect Dis, 2019 Mar;80:129-133.
    PMID: 30572022 DOI: 10.1016/j.ijid.2018.12.009
    OBJECTIVE: This study was performed to analyze the serotype distribution of Streptococcus pneumoniae causing invasive pneumococcal disease (IPD) in children aged 5 years and under in Malaysia and to assess the antimicrobial resistance.

    METHODS: From 2014 to 2017, a total of 245 invasive S. pneumoniae isolates from children ≤5 years of age were received from hospitals all around Malaysia. All isolates were identified and subjected to serotyping and antimicrobial susceptibility testing.

    RESULTS: Of the 245 isolates, 117 (48.0%) were from children aged <1year, 46 (19.05%) were from children aged 1-2 years, and 82 (33.0%) were from children aged 2-5 years. The most common serotypes were 14 (26.9%), 6B (19.6%), 19A (11.8%), 6A (10.6%), and 19F (6.9%) and vaccine coverage was 88.2% for PCV13, 64.1% for PCV10, and 63.3% for PCV7. Resistance to penicillin was 0.2% for non-meningitis cases and 22.2% for meningitis cases; erythromycin resistance was reported in 42.9%, co-trimoxazole in 35.9%, and tetracycline in 42.9%.

    CONCLUSIONS: Serotypes 14, 6B, 19A, 6A, and 19F were the most common serotypes isolated from children with IPD in Malaysia during this pre-vaccination era. The lack of reports on the serotype distribution has limited action for the implementation of PCV in the national immunization programme (NIP). The information from this study may benefit future policies for the introduction of PCV in the Malaysian NIP and ultimately may reduce the morbidity and mortality among children in Malaysia.

  8. Measurement of radiation attenuation parameters of modified defatted soy flour-soy protein isolate-based mangrove wood particleboards to be used for CT phantom production
    Samson DO, Jafri MZM, Shukri A, Hashim R, Sulaiman O, Aziz MZA, et al.
    Radiat Environ Biophys, 2020 08;59(3):483-501.
    PMID: 32333105 DOI: 10.1007/s00411-020-00844-z
    For the first time, Rhizophora spp. (Rh. spp.) particleboard phantoms were developed using defatted soy flour (DSF) and soy protein isolate (SPI) modified by sodium hydroxide and itaconic acid polyamidoamine-epichlorohydrin (IA-PAE) adhesive. The microstructural characterization and X-ray diffraction patterns of the material revealed that the modified DSF and SPI adhesives became more compact and homogeneous when NaOH/IA-PAE was added, which prevented damage by moisture. It was confirmed that the composite is crystalline with (101), (002), and (004) orientations. Phantoms made of this material were scanned with X-ray computed tomography (CT) typically used for abdominal examinations with varying energies corresponding to 80, 120, and 135 kVp, to determine CT numbers, electron densities, and density distribution profiles. The radiation attenuation parameters were found to be not significantly different from those of water (XCOM) with p values [Formula: see text] 0.05 for DSF and SPI. The DSF- and SPI-based particleboard phantoms showed CT numbers close to those of water at the three X-ray CT energies. In addition, electron density and density distribution profiles of DSF-SPI-Rh. spp. particleboard phantoms with 15 wt% IA-PAE content were even closer to those of water and other commercial phantom materials at the three X-ray CT energies. It is concluded that DSF-SPI with NaOH/IA-PAE added can be used as a potential adhesive in Rh. spp. particleboard phantoms for radiation dosimetry.
  9. Characterization of soy-lignin bonded Rhizophora spp. particleboard as substitute phantom material for radiation dosimetric studies - Investigation of CT number, mass attenuation coefficient and effective atomic number
    Zuber SH, Hashikin NAA, Mohd Yusof MF, Aziz MZA, Hashim R
    Appl Radiat Isot, 2021 Apr;170:109601.
    PMID: 33515930 DOI: 10.1016/j.apradiso.2021.109601
    Experimental particleboards are made from Rhizophora spp. wood trunk with three different percentages of lignin and soy flour (0%, 6% and 12%) as adhesives. The objective was to investigate the equivalence of Rhizophora spp. particleboard as phantom material with human soft tissue using Computed Tomography (CT) number. The linear and mass attenuation coefficient of Rhizophora spp. particleboard at low energy range was also explored using X-ray Fluorescence (XRF) configuration technique. Further characterization of the particleboard was performed to determine the effective atomic number, Zeff using Energy Dispersive X-Ray (EDX) method. Adhesive-bonded Rhizophora spp. particleboard showed close similarities with water, based on the average CT numbers, electron density calibration curve and the analysis of CT density profile, compared to the binderless particleboard. The effective atomic number obtained from the study indicated that the attenuation properties of all the particleboards at different percentages of adhesives were almost similar to water. The mass attenuation coefficient calculated from XRF configuration technique showed good agreement with water from XCOM database, suggesting its potential as phantom material for radiation study.
  10. Fulltext Crystal structure of 2-(1,3-dioxoindan-2-yl)iso-quinoline-1,3,4-trione
    Ghalib RM, Chidan Kumar CS, Hashim R, Sulaiman O, Fun HK
    Acta Crystallogr E Crystallogr Commun, 2015 Jan 1;71(Pt 1):o6-7.
    PMID: 25705509 DOI: 10.1107/S2056989014025997
    In the title iso-quinoline-1,3,4-trione derivative, C18H9NO5, the five-membered ring of the indane fragment adopts an envelope conformation with the nitro-gen-substituted C atom being the flap. The planes of the indane benzene ring and the iso-quinoline-1,3,4-trione ring make a dihedral angle of 82.06 (6)°. In the crystal, mol-ecules are linked into chains extending along the bc plane via C-H⋯O hydrogen-bonding inter-actions, enclosing R 2 (2)(8) and R 2 (2)(10) loops. The chains are further connected by π-π stacking inter-ations, with centroid-to-centroid distances of 3.9050 (7) Å, forming layers parallel to the b axis.
  11. Biodegradation of fibrillated oil palm trunk fiber by a novel thermophilic, anaerobic, xylanolytic bacterium Caldicoprobacter sp. CL-2 isolated from compost
    Widyasti E, Shikata A, Hashim R, Sulaiman O, Sudesh K, Wahjono E, et al.
    Enzyme Microb Technol, 2018 Apr;111:21-28.
    PMID: 29421033 DOI: 10.1016/j.enzmictec.2017.12.009
    Oil palm trunk (OPT) is one of the most promising lignocellulosic bioresources. To develop effective biodegradation, thermophilic, anaerobic microorganisms were screened from bovine manure compost using fibrillated OPT (f-OPT) pretreated by wet disk milling as the substrate. One thermophilic, anaerobic bacterium, strain CL-2, whose 16S rDNA gene has 98.6% sequence identity with that of Caldicoprobacter faecale DSM 20678T, exhibited high degradation activity (32.7% reduction in total dry solids of f-OPT). Strain CL-2 did not use cellulose as a carbon source, but used hemicelluloses such as xylan, arabinoxylan, starch and pectin at 70 °C. Phylogenetic and morphologic analyses and the polysaccharide use suggest that CL-2 may be classified as a novel species of Caldicoprobacter, named Caldicoprobacter sp. CL-2. To characterize enzymatic activities of CL-2, extracellular enzymes were prepared from culture broth using beechwood xylan as the carbon source. The extracellular enzymes showed high xylanase activity, but low cellulase activity, suggesting that f-OPT degradation may depend on xylanase activity. To understand the xylanase system of CL-2, a major xylanase was cloned and characterized. The xylanase (CalXyn11A) had a modular structure consisting of a glycoside hydrolase (GH) family-11 domain and a family 36 carbohydrate-binding module. CalXyn11A did not show f-OPT degradation activity, but a strong synergistic effect was observed when CalXyn11A was added to the extracellular enzyme preparation. These results indicate that, rather than working alone, CalXyn11A has an important role in enhancing total lignocellulose degradation activity by cooperation with other GHs.
  12. Probing n-Octyl α-d-Glycosides Using Deuterated Water in the Lyotropic Phase by Deuterium NMR
    Wan Iskandar WFN, Salim M, Patrick M, Timimi BA, Zahid NI, Hashim R
    J Phys Chem B, 2021 05 06;125(17):4393-4408.
    PMID: 33885309 DOI: 10.1021/acs.jpcb.0c10629
    The lyotropic phase behavior of four common and easily accessible glycosides, n-octyl α-d-glycosides, namely, α-Glc-OC8, α-Man-OC8, α-Gal-OC8, and α-Xyl-OC8, was investigated. The presence of normal hexagonal (HI), bicontinuous cubic (VI), and lamellar (Lα) phases in α-Glc-OC8 and α-Man-OC8 including their phase diagrams in water reported previously was verified by deuterium nuclear magnetic resonance (2H NMR), via monitoring the D2O spectra. Additionally, the partial binary phase diagrams and the liquid crystal structures formed by α-Gal-OC8 and α-Xyl-OC8 in D2O were constructed and confirmed using small- and wide-angle X-ray scattering and 2H NMR. The average number of bound water molecules (nb) per headgroup in the Lα phase was determined by the systematic measurement of the quadrupolar splitting of D2O over a wide range of molar ratio values (glycoside/D2O), especially at high glucoside composition. The number of bound water molecules bound to the headgroup was found to be around 1.5-2.0 for glucoside, mannoside, and galactoside, all of which possesses four OH groups. In the case of xyloside, which has only three OH groups, the bound water content is ∼2.0. Our findings confirmed that the bound water content of all n-octyl α-d-glycosides studied is lower compared to the number of possible hydrogen bonding sites possibly due to the fact that most of the OH groups are involved in intralayer interaction that holds the lipid assembly together.
  13. Fulltext Influence of Different Percentages of Binders on the Physico-Mechanical Properties of Rhizophora spp. Particleboard as Natural-Based Tissue-Equivalent Phantom for Radiation Dosimetry Applications
    Zuber SH, Hashikin NAA, Yusof MFM, Aziz MZA, Hashim R
    Polymers (Basel), 2021 Jun 04;13(11).
    PMID: 34199810 DOI: 10.3390/polym13111868
    Rhizophora spp. particleboard with the incorporation of lignin and soy flour as binders were fabricated and the influence of different percentages of lignin and soy flour (0%, 6% and 12%) on the physico-mechanical properties of the particleboard were studied. The samples were characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray fluorescence (XRF) and internal bonding. The results stipulated that the addition of binders in the fabrication of the particleboard did not change the functional groups according to the FTIR spectrum. For XRD, addition of binders did not reveal any major transformation within the composites. SEM and EDX analyses for all percentages of binders added showed no apparent disparity; however, it is important to note that the incorporation of binders allows better bonding between the molecules. In XRF analysis, lower percentage of chlorine in the adhesive-bonded samples may be advantageous in maintaining the natural properties of the particleboard. In internal bonding, increased internal bond strength in samples with binders may indicate better structural integrity and physico-mechanical strength. In conclusion, the incorporation of lignin and soy flour as binders may potentially strengthen and fortify the particleboard, thus, can be a reliable phantom in radiation dosimetry applications.
  14. Molecular characterization of Corynebacterium diphtheriae isolates in Malaysia between 1981 and 2016
    Mohd Khalid MKN, Ahmad N, Hii SYF, Abd Wahab MA, Hashim R, Liow YL
    J Med Microbiol, 2019 Jan;68(1):105-110.
    PMID: 30465638 DOI: 10.1099/jmm.0.000881
    Sporadic diphtheria cases in Malaysia have remained low in number since the 1990s. However, in 2016 a total of 31 cases were reported nationwide and to investigate this we performed molecular characterization of 30 Corynebacterium diphtheriae isolates collected from 1981 to 2016 using multilocus sequence typing (MLST). C. diphtheriae isolates were identified and biotyped using the API Coryne kit, while the toxigenicity was determined by PCR and the Elek test. All of the 2016 isolates belonged to biotype mitis, caused respiratory diphtheria and were toxigenic strains. MLST analysis identified 17 sequence types (STs), including 11 new ones. ST453 was the most common clone (7/30, 23.3 %), followed by ST141 (5/30, 16.7 %), ST451 (3/30, 10.0 %) and ST248 (2/30, 6.7 %). The clones identified in 2016 had not been detected in previous isolations and they were phylogenetically distinct. Our results suggest that the diphtheria cases in 2016 were caused by the emergence and spread of new clones in Malaysia.
  15. Characterization of the first isolate of Klebsiella pneumoniae carrying New Delhi metallo-β-lactamase and other extended spectrum β-lactamase genes from Malaysia
    Ahmad N, Hashim R, Shukor S, Mohd Khalid KN, Shamsudin F, Hussin H
    J Med Microbiol, 2013 May;62(Pt 5):804-806.
    PMID: 23449878 DOI: 10.1099/jmm.0.050781-0
  16. Detoxification of Sap from Felled Oil Palm Trunks for the Efficient Production of Lactic Acid
    Kunasundari B, Arai T, Sudesh K, Hashim R, Sulaiman O, Stalin NJ, et al.
    Appl Biochem Biotechnol, 2017 Sep;183(1):412-425.
    PMID: 28361245 DOI: 10.1007/s12010-017-2454-z
    The availability of fermentable sugars in high concentrations in the sap of felled oil palm trunks and the thermophilic nature of the recently isolated Bacillus coagulans strain 191 were exploited for lactic acid production under non-sterile conditions. Screening indicated that strain 191 was active toward most sugars including sucrose, which is a major component of sap. Strain 191 catalyzed a moderate conversion of sap sugars to lactic acid (53%) with a productivity of 1.56 g/L/h. Pretreatment of oil palm sap (OPS) using alkaline precipitation improved the sugar fermentability, providing a lactic acid yield of 92% and productivity of 2.64 g/L/h. To better characterize potential inhibitors in the sap, phenolic, organic, and mineral compounds were analyzed using non-treated sap and saps treated with activated charcoal and alkaline precipitation. Phthalic acid, 3,4-dimethoxybenzoic acid, aconitic acid, syringic acid, and ferulic acid were reduced in the sap after treatment. High concentrations of Mg, P, K, and Ca were also precipitated by the alkaline treatment. These results suggest that elimination of excess phenolic and mineral compounds in OPS can improve the fermentation yield. OPS, a non-food resource that is readily available in bulk quantities from plantation sites, is a promising source for lactic acid production.
  17. Draft Genome Sequence of a Highly Resistant Streptococcus pneumoniae Serotype 15A Strain Isolated from Blood
    Arushothy R, Ahmad N, Amran F, Hashim R, Samsuddin N, Che Azih CR
    Genome Announc, 2018 Apr 19;6(16).
    PMID: 29674530 DOI: 10.1128/genomeA.00167-18
    After the introduction of the pneumococcal conjugate vaccine in Malaysia in recent years, the emergence of nonvaccine serotypes is of concern, particularly the antibiotic-resistant strains, with an increase specifically in serotype 15A. Here, we report the draft genome sequence of Streptococcus pneumoniae strain SS40_16, isolated from the blood sample of a 19-month-old female in 2016. SS40_16 is a multidrug-resistant strain with resistance to penicillin (MIC, ≥2 µg/ml), tetracycline, and trimethoprim-sulfamethoxazole. The strain belongs to serotype 15A and sequence type 1591 (ST1591).
  18. Fulltext A SNP-based phylogenetic analysis of Corynebacterium diphtheriae in Malaysia
    Hii SYF, Ahmad N, Hashim R, Liow YL, Abd Wahab MA, Mohd Khalid MKN
    BMC Res Notes, 2018 Oct 25;11(1):760.
    PMID: 30359301 DOI: 10.1186/s13104-018-3868-6
    OBJECTIVE: There is a lack of study in Corynebacterium diphtheriae isolates in Malaysia. The alarming surge of cases in year 2016 lead us to evaluate the local clinical C. diphtheriae strains in Malaysia. We conducted single nucleotide polymorphism phylogenetic analysis on the core and pan-genome as well as toxin and diphtheria toxin repressor (DtxR) genes of Malaysian C. diphtheriae isolates from the year 1986-2016.

    RESULTS: The comparison between core and pan-genomic comparison showed variation in the distribution of C. diphtheriae. The local isolates portrayed a heterogenous trait and a close relationship between Malaysia's and Belarus's, Africa's and India's strains were observed. A toxigenic C. diphtheriae clone was noted to be circulating in the Malaysian population for nearly 30 years and from our study, the non-toxigenic and toxigenic C. diphtheriae strains can be differentiated significantly into two large clusters, A and B respectively. Analysis against vaccine strain, PW8 portrayed that the amino acid composition of toxin and DtxR in Malaysia's local strains are well-conserved and there was no functional defect noted. Hence, the change in efficacy of the currently used toxoid vaccine is unlikely to occur.

  19. Fulltext Multidrug-resistant Streptococcus pneumoniae causing invasive pneumococcal disease isolated from a paediatric patient
    Arushothy R, Ramasamy H, Hashim R, Raj A S S, Amran F, Samsuddin N, et al.
    Int J Infect Dis, 2020 Jan;90:219-222.
    PMID: 31682962 DOI: 10.1016/j.ijid.2019.10.037
    The emergence of non-vaccine multidrug-resistant Streptococcus pneumoniae serotypes is on rise. This study was performed to investigate a highly resistant serotype 15A S. pneumoniae isolated from the blood specimen of a 20-month-old patient who died of her infection. The SS40_16 isolate was resistant to erythromycin, co-trimoxazole, tetracycline, and chloramphenicol, as well as to penicillin, ceftriaxone, and cefotaxime (using meningitis cut-off points, Clinical and Laboratory Standards Institute). The isolate belonged to sequence type 1591 (ST1591) and was related to CC81 clonal complex, suggesting the possibility of horizontal gene transfer. Scanning electron microscopy comparison between resistant and sensitive pneumococcal isolates also indicated similar phenotypic characteristics that confer high resistance. The emergence of highly resistant non-vaccine pneumococci is of great concern to public health and in the clinical setting. Pneumococcal surveillance programs represent a crucial tool, not only for determining the impact of pneumococcal conjugate vaccines, but also for monitoring the selective pressure of serotype replacement with regard to the treatment of invasive pneumococcal disease.
  20. Structural control of the dielectric, pyroelectric and ferroelectric properties of poly(vinylidene fluoride-co-trifluoroethylene) thin films
    Ng CYB, Gan WC, Velayutham TS, Goh BT, Hashim R
    Phys Chem Chem Phys, 2020 Jan 29;22(4):2414-2423.
    PMID: 31939468 DOI: 10.1039/c9cp01556f
    The effects of solvents and temperature on the crystal formation were investigated for vinylidene fluoride/trifluoroethylene copolymer P(VDF-TrFE). Highly crystalline P(VDF-TrFE) thin films were fabricated by spin-casting using various polar solvents such as diethyl carbonate (DEC), methyl ethyl ketone (MEK), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Ferroelectric polarisation reversal of the P(VDF-TrFE) was evidenced by a displacement (D)-electric field (E) hysteresis loop measurement and supported by the presence of pyroelectric activity. The samples which were annealed above 100 °C gave elongated rod-like crystalline structures and the highest crystallinity, Xc of 83% was formed at 120 °C. Consequently, remnant polarisation (85 mC m-2) and the pyroelectric coefficient (30 μC m-2 K-1) were enhanced. Thus, annealing plays a substantial role in controlling the crystalline structure of P(VDF-TrFE) films regardless of the choice of solvent. Although, the crystalline structure control is almost independent of the solvent's polarity, the choice of solvent is essential in preparing a smoother film surface. Molecular dynamics of P(VDF-TrFE) are discussed from the observation of two dielectric relaxation processes, β and γ related to the segmental micro-Brownian and local modes, respectively. The complete ferroelectric polarization reversal caused a reduction in the dielectric polarization and reduced the lattice spacing of the 110/200 planes.
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