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Application of optimized large surface area date stone (Phoenix dactylifera ) activated carbon for rhodamin B removal from aqueous solution: Box-Behnken design approach

Danish M, Khanday WA, Hashim R, Sulaiman NS, Akhtar MN, Nizami M

Ecotoxicol Environ Saf, 2017 May;139:280-290.
PMID: 28167440 DOI: 10.1016/j.ecoenv.2017.02.001

Box-Behnken model of response surface methodology was used to study the effect of adsorption process parameters for Rhodamine B (RhB) removal from aqueous solution through optimized large surface area date stone activated carbon. The set experiments with three input parameters such as time (10-600min), adsorbent dosage (0.5-10g/L) and temperature (25-50°C) were considered for statistical significance. The adequate relation was found between the input variables and response (removal percentage of RhB) and Fisher values (F- values) along with P-values suggesting the significance of various term coefficients. At an optimum adsorbent dose of 0.53g/L, time 593min and temperature 46.20°C, the adsorption capacity of 210mg/g was attained with maximum desirability. The negative values of Gibb(')s free energy (ΔG) predicted spontaneity and feasibility of adsorption; whereas, positive Enthalpy change (ΔH) confirmed endothermic adsorption of RhB onto optimized large surface area date stone activated carbons (OLSADS-AC). The adsorption data were found to be the best fit on the Langmuir model supporting monolayer type of adsorption of RhB with maximum monolayer layer adsorption capacity of 196.08mg/g.
Fulltext Analysis using image segmentation for the elemental composition of activated carbon

Danish M, Akhtar MN, Hashim R, Saleh JM, Bakar EA

MethodsX, 2020;7:100983.
PMID: 32742942 DOI: 10.1016/j.mex.2020.100983

This article encompasses the method related to image segmentation of the Field Emission Scanning Electron Microscope (FESEM) images of Acacia Mangium Wood derived Activated Carbons under different conditions. Image segmentation using Hue-Saturation-Value (HSV) thresholding method was adapted to identify the different pattern composition in the grayscale images by varying the intensity Value (V) and keeping Hue (H) and Saturation (S) to zero, and each pattern was considered as one type of element that constituted the Activated Carbon. The algorithm was developed to compute the percentage of each pattern using non-zero pixels, and on the basis of different patterns, different elements having certain percentage of composition were recorded. Later, these results were compared with the Energy Dispersive X-ray Spectroscopy (EDS) to cross check the difference in percentage of each element present at the surface of the Activated Carbon. Part of this result is published in the article [1], "Comparison of surface properties of wood biomass Activated Carbons and their application against rhodamine B and methylene blue dye" Surfaces and Interfaces vol. 11 (2018) pp1-13.•The methods involved will be useful for characterization of Activated Carbon materials.•Image segmentation using HSV thresholding will inspire other researchers to apply similar concept on other materials.•Different patterns obtained for FESEM images using HSV thresholding was able to determine the presence of multiple elements present in the prepared Activated Carbon samples.
Maintaining an ant-plant symbiosis: secondary polygyny in the Macaranga triloba-Crematogaster sp. association

Feldhaar H, Fiala B, bin Hashim R, Maschwitz U

Naturwissenschaften, 2000 Sep;87(9):408-11.
PMID: 11091965
Fulltext Estimation and validation of Nearshore Current at the Coast of Carey Island, Malaysia

Fitri, A., Hashim, R., Motamedi, S.

Pertanika Journal of Science & Technology, 2017;25(3):1009-1018.
MyJurnal

This study simulates the nearshore current characteristics at Carey Island by using MIKE 21 Hydrodynamic FM. The model simulations are calibrated and validated against measured conditions by adjusting the values of bed resistant over the stipulated computation domain. To evaluate the accuracy of the simulation results, three statistical parameters, namely RMSE, R Squared, and Thiel’s inequality coefficients are calculated to compare the observed and simulated results. The results indicate that the current speeds during the spring tide are approximately between 0 m/s and 0.64 m/s which come from Northwest to southeast direction. A good agreement between observed and simulated values of current speeds, current direction and water level with R squared of approximately 0.92 to 0.95 are obtained. Results suggest that the bed resistant is an important parameter in the hydrodynamic simulation using MIKE 21 Hydrodynamic FM.
Phytochemical analysis, cytotoxic activity and constituents-activity relationships of the leaves of Cinnamomum iners (Reinw. ex Blume-Lauraceae)

Ghalib RM, Hashim R, Sulaiman O, Mehdi SH, Anis Z, Rahman SZ, et al.

Nat Prod Res, 2012;26(22):2155-8.
PMID: 22181707 DOI: 10.1080/14786419.2011.633083

The leaves of Cinnamomum iners (Reinw. ex Blume-Lauraceae) have been refluxed successively with chloroform and alcohol to get chloroform extract and alcoholic extract. Both the extracts have been assayed for cytotoxicity against human colorectal tumour cells. The chloroform extract exhibited significant cytotoxicity with IC(50) 31 µg mL(-1) (p 200 µg mL(-1). The chloroform extract has been further proceeded for chemical analysis by GC-TOFMS and 178 components were identified including acids, amines, amides, aldehydes, alcohols, esters, benzene derivatives, bicyclic compounds, terpenes, hydrocarbons, naphthalene derivatives, furan derivatives, azulenes, etc. Nine components representing 51.73% of the total chloroform extract were detected as major components. Caryophyllene (14.41%) and Eicosanoic acid ethyl ester (12.17%) are the most prominent components of the chloroform extract. β-Caryophyllene (14.41%) as most abundant compound supports potent cytotoxicity as shown by chloroform extract.
A novel caryophyllene type sesquiterpene lactone from Asparagus falcatus (Linn.); structure elucidation and anti-angiogenic activity on HUVECs

Ghalib RM, Hashim R, Sulaiman O, Mehdi SH, Valkonen A, Rissanen K, et al.

Eur J Med Chem, 2012 Jan;47(1):601-7.
PMID: 22074984 DOI: 10.1016/j.ejmech.2011.10.037

In this study the novel caryophyllene type sesquiterpene lactone (aspfalcolide) has been isolated from the leaves of Asparagus falcatus (Linn.) and characterized by IR, 1D NMR, 2D NMR, EI-MS, HR-ESI-MS and X-ray single crystal diffraction analysis. The aspfalcolide crystallizes in the orthorhombic space group P2(1)2(1)2(1) with a = 6.37360(10), b = 7.6890(2), c = 27.3281(6) Å, α = β = γ = 90(°) and Z = 4. One intermolecular O-H⋯O hydrogen bond enforces these natural molecules to form infinite chains through the crystal. Aspfalcolide was screened for its anti-angiogenic activity in human umbilical vein endothelial cells (HUVECs) and the result showed the remarkable inhibitory effect of aspfalcolide on the proliferation (IC(50) 1.82 μM), migration and tube formation of HUVECs.
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.
Degeneration patterns of the worker spermatheca during morphogenesis in ants (Hymenoptera: Formicidae)

Gotoh A, Billen J, Hashim R, Ito F

Evol. Dev., 2016 Mar;18(2):96-104.
PMID: 26994860 DOI: 10.1111/ede.12182

Reproductive division of labor is one of the crucial features in social insects, however, the developmental mechanisms leading to modifications in the reproductive apparatus of workers are still not very clear. Ants show a remarkable diversity in the morphological specialization of the worker's reproductive apparatus, that allows to distinguish four types, type 1: workers that have ovaries and a functional spermatheca, and that reproduce like queens, type 2: workers have ovaries and a vestigial spermatheca, type 3: workers have ovaries but no spermatheca, and type 4: workers lost both ovaries and spermatheca. We investigated morphogenesis of the worker spermatheca in 28 ant species by histological examination. In workers of type 1, the morphogenesis of the spermatheca is very similar to that in ant queens. In type 2, the spermathecal disc also differentiates, however, the development is interrupted and remains vestigial. In types 3 and 4, the absence of the spermatheca in the adult phase is caused by a degeneration after initial formation of the spermathecal disc or by a complete lack of the spermathecal discs. The timing of these interruption and degeneration events varies among species. The species exhibiting an earlier interrupting point of spermatheca formation in workers have a larger queen-worker dimorphism, that seems to be independent from ant phylogeny.
Macroscopic order in a nematic liquid crystal: Perturbation by spontaneous director fluctuations

Hamasuna D, Hashim R, Kasatani A, Luckhurst GR, Sugimura A, Timimi BA, et al.

Phys Rev E Stat Nonlin Soft Matter Phys, 2015 Jun;91(6):062502.
PMID: 26172726

The dynamic alignment of the nematic director by near-orthogonal electric and magnetic fields has been investigated. The intermediate states during the relaxation process were found, with the aid of time-resolved deuterium NMR spectroscopy, to be markedly nonuniform. The macroscopic order was perturbed, although the initial and final states of the director appear to be essentially uniform. However, the initial state does have a profound influence on the uniformity of the director in the intermediate states. We have developed a fundamental model based on the effect of spontaneous director fluctuations to explain these unusual NMR observations.
Fulltext Screening of aphrodisiac property in sea slug, Aplysia dactylomela

Hashim R, Roslan NA, Zulkipli FH, Daud JM

Asian Pac J Trop Med, 2014 Sep;7S1:S150-4.
PMID: 25312111 DOI: 10.1016/S1995-7645(14)60222-4

OBJECTIVE: To evaluate the aphrodisiac property of Aplysia dactylomela (A. dactylomelan), locally known as 'dugu-dugu', which is one of the sea slug species.
METHODS: Two types of extractions were used; aqueous and lipid. Three doses of each A. dactylomelan extract, respectively; 50, 100, 200 mg/kg were administered (i.p.) to male mice for mounting behavior test. Sildenafil citrate or Viagra® (5 mg/kg) being positive control while negative control received saline solution.
RESULTS: The animals treated with lipid extract at the respective dose exhibited mounting behavior, but the mounting frequency decreased at higher doses (100 and 200 mg/kg). However, all doses of aqueous extract did not show any mounting behavior. Meanwhile, in all doses of lipid extracts administered displayed significant difference (P<0.05) from the positive control. Despite this, only the lipid extract of 50 mg/kg showed significant difference (P<0.05) with negative control. This signifies that lipid extracts especially in dose 50 mg/kg have a substantial effect of aphrodisiac property. In addition, the presence of steroids was detected in the phytochemical screening of lipid extract.
CONLUSIONS: The findings from this study provides preliminary scientific evidence that A. dactylomela could be used as an alternative medication of natural product for promoting sexual activity in men.
A reevaluation of the epimeric and anomeric relationship of glucosides and galactosides in thermotropic liquid crystal self-assemblies

Hashim R, Mirzadeh SM, Heidelberg T, Minamikawa H, Yoshiaki T, Sugimura A

Carbohydr Res, 2011 Dec 27;346(18):2948-56.
PMID: 22088885 DOI: 10.1016/j.carres.2011.10.032

Anomers and epimers α- and β-gluco and -galactosides are expected to behave differently. However, recent results on a series of Guerbet glycosides have indicated similar liquid crystal clearing temperatures for pure β-glucosides and the corresponding α-galactosides. This observation has led to speculation on similarities in the self-assembly interactions between the two systems, attributed to the trans-configuration of the 4-OH group and the hydrophobic aglycon. Previous simulations on related bilayers systems support this hypothesis, by relating this clearing transition temperature to intralayer (sugar-sugar) hydrogen bonding. In order to confirm the hypothesis, the comparison was expanded to include the cis-configurated pair, that is, α-gluco/β-galactoside. A set of α-configurated Guerbet glucosides as well as octyl α-galactoside were prepared and their thermotropic phase behavior studied. The data obtained enabled a complete comparison of the isomers of interest. While the results in general are in line with a pairing of the stereo-isomers according to the indicated cis/trans-configuration, differences within the pairs can be explained based on the direction of hydrogen bonds from a simple modeling study.
Some of the properties of flame retardant medium density fiberboard made from rubberwood and recycled containers containing aluminum trihydroxide

Hashim R, How LS, Kumar RN, Sulaiman O

Bioresour Technol, 2005 Nov;96(16):1826-31.
PMID: 16051090

The flame retardancy of medium density fiberboard (MDF) made from mixture of rubberwood fibers and recycled old corrugated containers was studied. Aluminum trihydroxide (ATH) was used as a fire retardant additive and mixed with the fibers to manufacture experimental MDF panels using wet process. Phenol formaldehyde (PF) resin in liquid, 2% based on oven dry weight of fibers, was used along with 0%, 10%, 15% and 20% of ATH. The flame retardant test was done using the limiting oxygen index (LOI) test. The other properties investigated include internal bond strength, thickness swelling and water absorption. The results showed that ATH loading increased as the LOI of MDF increased. This demonstrated that ATH could improved the fire retardant property of MDF at sufficient loading. An increase in concentration of ATH showed an increase in the IB values of MDF made without resin. MDF panels made without resin showed a progressive increase in internal bond as the composition of recycled old corrugated containers fiber increased. Addition of resin improved internal bond strength and reduced thickness swelling, and water absorption. Thickness swelling of panel increased as the composition of recycled old corrugated containers fiber increased. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that there is indication of ATH and resin filling the void space in between fibers.
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.
Fulltext Determination of Heavy Metal Levels in Fishes from the Lower Reach of the Kelantan River, Kelantan, Malaysia

Hashim R, Song TH, Muslim NZ, Yen TP

Trop Life Sci Res, 2014 Dec;25(2):21-39.
PMID: 27073597 MyJurnal

This study aimed to assess the concentrations of cadmium (Cd), nickel (Ni) and lead (Pb) in the tissues of fish collected from the lower reach of the Kelantan River, Malaysia. Fishes were collected using gill nets during the dry and wet seasons. A total of 78 individual fish were caught and comprised 6 families, 11 genera and 13 species. The dorsal muscle was analysed using a graphite furnace Atomic Absorption Spectrometer (AAS). The mean concentration of Cd in Chitala chitala (0.076 mg/kg) was above the critical limit values of the European Commission (EC), World Health Organization (WHO) and Food and Agriculture Organization (FAO). The mean concentrations of Cd in Barbonymus gonionatus and Tachysurus maculatus were already at the level of concern, whereas the other species were approaching the limits of permissible levels. No fish samples were found to have a Ni level higher than the permissible limit of 0.5-0.6 mg/kg set by the WHO (1985). Osteochilus hasseltii (0.169 mg/kg) and T. maculatus (0.156 mg/kg) showed high Pb concentrations. The concentrations of heavy metals were found to be elevated in the wet season (p<0.05). Omnivorous fish were detected with elevated concentrations of Cd and Ni, whereas carnivorous fish had the highest concentration of Pb. The concentrations of Cd and Pb in fish tissues were positively correlated with fish weight (p<0.05). This study determined that the fish species caught in the Kelantan River were contaminated with non-essential metals (Cd, Ni and Pb). Nevertheless, the heavy metal concentration in the fish tissues, with the exception of C. chitala, O. hasseltii and T. maculatus, did not exceed the EC, FAO, Malaysian Food Act (MFA) or WHO guidelines.
Fulltext Fish assemblages in streams subject to anthropogenic disturbances along the natchez trace parkway, Mississippi, USA

Hashim R, Jackson DC

Trop Life Sci Res, 2009 Dec;20(2):29-47.
PMID: 24575177 MyJurnal

A three-year study (July 2000 - June 2003) of fish assemblages was conducted in four tributaries of the Big Black River: Big Bywy, Little Bywy, Middle Bywy and McCurtain creeks that cross the Natchez Trace Parkway, Choctaw County, Mississippi, USA. Little Bywy and Middle Bywy creeks were within watersheds influenced by the lignite mining. Big Bywy and Middle Bywy creeks were historically impacted by channelisation. McCurtain Creek was chosen as a reference (control) stream. Fish were collected using a portable backpack electrofishing unit (Smith-Root Inc., Washington, USA). Insectivorous fish dominated all of the streams. There were no pronounced differences in relative abundances of fishes among the streams (P > 0.05) but fish assemblages fluctuated seasonally. Although there were some differences among streams with regard to individual species, channelisation and lignite mining had no discernable adverse effects on functional components of fish assemblages suggesting that fishes in these systems are euryceous fluvial generalist species adapted to the variable environments of small stream ecosystems.
Anhydrous octyl-glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields

Hashim R, Sugimura A, Nguan HS, Rahman M, Zimmermann H

J Chem Phys, 2017 Feb 28;146(8):084702.
PMID: 28249421 DOI: 10.1063/1.4976979

A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of octyl-b-D-glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.
Fulltext Identification and in vitro antimicrobial susceptibility of Brucella species isolated from human brucellosis

Hashim R, Ahmad N, Mohamed Zahidi J, Tay BY, Mohd Noor A, Zainal S, et al.

Int J Microbiol, 2014;2014:596245.
PMID: 25120569 DOI: 10.1155/2014/596245

Brucellosis is a world-wide zoonotic disease with a major impact on the public health. Due to the high risk of laboratory acquired infection, limited laboratory investigations were performed on this organism, including detailed identification and susceptibility study. Brucella melitensis is the commonest aetiological agent for human brucellosis in this region. The in vitro susceptibility pattern against selected antimicrobial agents was assessed using E-test. All isolates were noted to be sensitive to all the antimicrobial agents tested except for rifampicin where elevated MIC > 1 μg/mL was noted in 30 out of 41 isolates tested.
Detection of betalactamase producing bacterial genes and their clinical features

Hashim RB, Husin S, Rahman MM

Pak J Biol Sci, 2011 Jan 01;14(1):41-6.
PMID: 21913496

The present study was aimed to identify the gene of drug resistance betalactamase producing bacteria and clinical features of the infected patients at Hospital University Kebangsaan Malaysia. Blood samples from the patients were collected, processed and betalactamase producing drug resistance bacteria were identified by antibiotic sensitivity testing. Genes of the drug resistance bacteria were detected and characterized by polymerase chain reaction. A total of 34 isolates of drug resistance Betalactamase producing E. coli and Klebsiella spp. were isolated from 2,502 patients. Most common drug resistance gene TEM was found in 50% of the isolates. 11% was found positive for both TEM and SHV. Next 11% of the isolates expressed only SHV genes. Clinical features of the patients were recorded from where the bacteria isolated. Regarding community affiliations 70.5% of the infected patients were Malay 17.6% were Indian and 11.7% were Chinese. Majority of the patients has an underlying pre-morbid condition as reflected by their diagnosis. Better infection control and hygiene in hospitals, plus controlled and prudent use of antibiotics, is required to minimize the impact of drug resistance betalactamase producing bacteria and the spread of infections.
Fulltext Distribution, Prevalence, and Antibiotic Susceptibility Profiles of Infectious Noncholera Vibrio Species in Malaysia

Hassan M, Mohd Ali MR, Zamri HF, Nor Amdan NA, Azmai MNA, Maniam S, et al.

J Trop Med, 2023;2023:2716789.
PMID: 37274080 DOI: 10.1155/2023/2716789

BACKGROUND: The noncholera Vibrio spp. which cause vibriosis are abundantly found in our water ecosystem. These bacteria could negatively affect both humans and animals. To date, there is a paucity of information available on the existence and pathogenicity of this particular noncholera Vibrio spp. in Malaysia in comparison to their counterpart, Vibrio cholera.
METHODS: In this study, we extracted retrospective data from Malaysian surveillance database. Analysis was carried out using WHONET software focusing noncholera Vibrio spp. including Vibrio parahaemolyticus, Vibrio vulnificus, Vibrio fluvialis, Vibrio alginolyticus, Vibrio hollisae (Grimontia hollisae), Vibrio mimicus, Vibrio metschnikovii, and Vibrio furnissii.
RESULTS: Here, we report the first distribution and prevalence of these species isolated in Malaysia together with the antibiotic sensitivity profile based on the species. We found that V. parahaemolyticus is the predominant species isolated in Malaysia. Noticeably, across the study period, V. fluvialis is becoming more prevalent, as compared to V. parahaemolyticus. In addition, this study also reports the first isolation of pathogenic V. furnissii from stool in Malaysia.
CONCLUSION: These data represent an important step toward understanding the potential emergence of noncholera Vibrio spp. outbreaks.
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.

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