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Fulltext 2-(3,5-Di-tert-butyl-4-hydroxy-benzyl-sulfan-yl)nicotinic acid

Mansor S, Yehye WA, Ariffin A, Rahman NA, Ng SW

Acta Crystallogr Sect E Struct Rep Online, 2008;64(Pt 9):o1778.
PMID: 21201758 DOI: 10.1107/S1600536808026056

Two mol-ecules of the title compound, C(21)H(27)NO(3)S, are disposed about a center of inversion, generating an O-H⋯O hydrogen-bonded dimer.
Fulltext Di-n-butyl-ammonium 2-(3,5-di-tert-butyl-4-hydroxy-benzyl-sulfan-yl)nicotinate

Mansor S, Yehye WA, Ariffin A, Rahman NA, Ng SW

Acta Crystallogr Sect E Struct Rep Online, 2008;64(Pt 9):o1799.
PMID: 21201778 DOI: 10.1107/S1600536808026202

The asymmetric unit of the title compound, C(8)H(20)N(+)·C(21)H(26)NO(3)S(-), contains two indpendent ion pairs which are disposed about a psuedo-inversion center, generating an ammonium-carboxylate N-H⋯O hydrogen-bonded four-component cluster. In the crystal structure, adjacent clusters are linked by hydr-oxy-carboxylate O-H⋯O hydrogen bonds, forming a chain.
Fulltext N-Acetyl-2-hydroxy-N'-[methoxy(1-methylindol-2-yl)methyl]benzohydrazide

Yehye WA, Rahman NA, Ariffin A, Ng SW

Acta Crystallogr Sect E Struct Rep Online, 2008 Aug 23;64(Pt 9):o1824.
PMID: 21201799 DOI: 10.1107/S1600536808026846

In the crystal structure of the title Schiff-base, C(20)H(21)N(3)O(4), the amino group forms an N-H⋯O hydrogen bond to the acetyl group of an adjacent mol-ecule, forming a zigzag chain. The 2-hydr-oxy group is inter-nally hydrogen bonded to the amido group though an O-H⋯O hydrogen bond.
Serotyping of Brunei pneumococcal clinical strains and the investigation of their capability to adhere and invade a brain endothelium model

Rahman NA, Sharudin A, Diah S, Muharram SH

Microb Pathog, 2017 Sep;110:352-358.
PMID: 28711510 DOI: 10.1016/j.micpath.2017.07.021

INTRODUCTION: Pneumococcal infections have caused morbidity and mortality globally. Streptococcus pneumoniae (pneumococci) are commensal bacteria that colonize the nasopharynx, asymptomatically. From there, pneumococci can spread in the lungs causing pneumonia and disseminate in the bloodstream causing bacteremia (sepsis) and reach the brain leading to meningitis. Endothelial cells are one of the most important components of the blood-brain barrier that separates the blood from the brain and plays the first protective role against pneumococcal entry. Thus this study aimed to investigate on the ability of non-meningitis pneumococcal clinical strains to adhere and invade a brain endothelium model.
METHODS: Two pneumococcal Brunei clinical strains were serotyped by multiplex PCR method using oligonucleotide sequences derived from Centers for Disease Control and Prevention. A validated immortalised mouse brain endothelial cell line (bEnd.3) was used as a brain endothelium model for the study of the pneumococcal breach of the blood-brain barrier using an adherence and invasion assay.
RESULTS: Both of the pneumococcal clinical strains were found to be serotype 19F, a common circulating serotype in Southeast Asia and globally and possess the ability to adhere and invade the brain endothelial cells.
CONCLUSION: In addition, this is the first report on the serotype identification of pneumococci in Brunei Darussalam and their application on a brain endothelium model. Further studies are required to understand the virulence capabilities of the clinical strains.
Fulltext Floating teeth appearance: A radiographic dilemma

Rahman NA, Harun MH, Rahman SA, Mohammad NSA

J Taibah Univ Med Sci, 2020 Apr;15(2):160-165.
PMID: 32368214 DOI: 10.1016/j.jtumed.2020.02.005

Gorham disease (GD) is an extremely rare disorder that is characterised by massive osteolysis of the affected bone with unknown aetiology and an unpredictable prognosis. Additionally, no standard treatment is available for GD. This article describes a case report of a 61-year-old Malay woman who was diagnosed with GD of the anterior mandible without a prior history of trauma. She presented with pain and mobility of the dentoalveolar segment for 3 months. The radiographic findings showed "floating teeth" with widening of the periodontal ligament space and localized area of bony destruction. Histopathologically, there was proliferation of numerous dilated endothelial-lined channels within the intertrabecular tissue. Some areas of bone were replaced by fibrous connective tissue giving rise to the appearance of a benign fibroosseous lesion. The patient was managed with simple removal of the affected bone segment under local anaesthesia, followed by prosthodontic rehabilitation. Healing of the surgical site was uneventful, and no recurrence was reported at the 3-year follow-up.
Fulltext Cost analysis of facial injury treatment in two university hospitals in Malaysia: a prospective study

Saperi BS, Ramli R, Ahmed Z, Muhd Nur A, Ibrahim MI, Rashdi MF, et al.

Clinicoecon Outcomes Res, 2017;9:107-113.
PMID: 28223831 DOI: 10.2147/CEOR.S119910

OBJECTIVE: Facial injury (FI) may occur in isolation or in association with injuries to other parts of the body (facial and other injury [FOI]). The objective of this study was to determine the direct treatment costs incurred during the management of facial trauma.
MATERIALS AND METHODS: A prospective cohort study on treatment cost for FIs and FOIs due to road-traffic crashes in two university hospitals in Malaysia was conducted from July 2010 to June 2011. The patients were recruited from emergency departments and reviewed after 6 months from the date of initial treatment. Direct cost analysis, comparison of cost and length of hospital stay, and Injury Severity Score (ISS) were performed.
RESULTS: A total of 190 patients were enrolled in the study, of whom 83 (43.7%) had FI only, and 107 (56.3%) had FOI. The mean ISS was 5.4. The mean length of stay and costs for patients with FI only were 5.8 days with a total cost of US$1,261.96, whereas patients with FOI were admitted for 7.8 days with a total cost of US$1,716.47. Costs doubled if the treatment was performed under general anesthesia compared to local anesthesia.
CONCLUSION: Treatment of FI and FOI imposes a financial burden on the health care system in Malaysia.
Fulltext Detection of human papillomavirus in oropharyngeal squamous cell carcinoma

Fauzi FH, Hamzan NI, Rahman NA, Suraiya S, Mohamad S

J Zhejiang Univ Sci B, 2021 4 13;21(12):961-976.
PMID: 33843162 DOI: 10.1631/jzus.B2000161

Worldwide there has been a significant increase in the incidence of oropharyngeal squamous cell carcinoma (OPSCC) etiologically attributed to oncogenic human papillomavirus (HPV). Reliable and accurate identification and detection tools are important as the incidence of HPV-related cancer is on the rise. Several HPV detection methods for OPSCC have been developed and each has its own advantages and disadvantages in regard to sensitivity, specificity, and technical difficulty. This review summarizes our current knowledge of molecular methods for detecting HPV in OPSCC, including HPV DNA/RNA polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), p16 immunohistochemistry (IHC), and DNA/RNA in situ hybridization (ISH) assays. This summary may facilitate the selection of a suitable method for detecting HPV infection, and therefore may help in the early diagnosis of HPV-related carcinoma to reduce its mortality, incidence, and morbidity.
The effect of mild hearing loss on academic performance in primary school children

Khairi Md Daud M, Noor RM, Rahman NA, Sidek DS, Mohamad A

Int J Pediatr Otorhinolaryngol, 2010 Jan;74(1):67-70.
PMID: 19913305 DOI: 10.1016/j.ijporl.2009.10.013

To determine the prevalence of mild hearing loss and its association with academic performance among primary school children.
Application of the linear interaction energy method (LIE) to estimate the binding free energy values of Escherichia coli wild-type and mutant arginine repressor C-terminal domain (ArgRc)-l-arginine and ArgRc-l-citrulline protein-ligand complexes

Asi AM, Rahman NA, Merican AF

J Mol Graph Model, 2004 Mar;22(4):249-62.
PMID: 15177077

Protein-ligand binding free energy values of wild-type and mutant C-terminal domain of Escherichia coli arginine repressor (ArgRc) protein systems bound to L-arginine or L-citrulline molecules were calculated using the linear interaction energy (LIE) method by molecular dynamics (MD) simulation. The binding behaviour predicted by the dissociation constant (K(d)) calculations from the binding free energy values showed preferences for binding of L-arginine to the wild-type ArgRc but not to the mutant ArgRc(D128N). On the other hand, L-citrulline do not favour binding to wild-type ArgRc but prefer binding to mutant ArgRc(D128N). The dissociation constant for the wild-type ArgRc-L-arginine complex obtained in this study is in agreement with reported experimental results. Our results also support the experimental data for the binding of L-citrulline to the mutant ArgRc(D128N). These showed that LIE method for protein-ligand binding free energy calculation could be applied to the wild-type and the mutant E. coli ArgRc-L-arginine and ArgRc-L-citrulline protein-ligand complexes and possibly to other transcriptional repressor-co-repressor systems as well.
Computational docking of L-arginine and its structural analogues to C-terminal domain of Escherichia coli arginine repressor protein (ArgRc)

Kueh R, Rahman NA, Merican AF

J Mol Model, 2003 Apr;9(2):88-98.
PMID: 12707802

The arginine repressor (ArgR) of Escherichia coli binds to six L-arginine molecules that act as its co-repressor in order to bind to DNA. The binding of L-arginine molecules as well as its structural analogues is compared by means of computational docking. A grid-based energy evaluation method combined with a Monte Carlo simulated annealing process was used in the automated docking. For all ligands, the docking procedure proposed more than one binding site in the C-terminal domain of ArgR (ArgRc). Interaction patterns of ArgRc with L-arginine were also observed for L-canavanine and L-citrulline. L-lysine and L-homoarginine, on the other hand, were shown to bind poorly at the binding site. Figure A general overview of the sites found from docking the various ligands into ArgRc ( grey ribbons). Red coloured sticks: residues in binding site H that was selected for docking
Fulltext Saccharification of rice straw by cellulase from a local Trichoderma harzianum SNRS3 for biobutanol production

Rahnama N, Foo HL, Abdul Rahman NA, Ariff A, Md Shah UK

BMC Biotechnol, 2014;14:103.
PMID: 25496491 DOI: 10.1186/s12896-014-0103-y

Rice straw has shown to be a promising agricultural by-product in the bioconversion of biomass to value-added products. Hydrolysis of cellulose, a main constituent of lignocellulosic biomass, is a requirement for fermentable sugar production and its subsequent bioconversion to biofuels such as biobutanol. The high cost of commercial enzymes is a major impediment to the industrial application of cellulases. Therefore, the use of local microbial enzymes has been suggested. Trichoderma harzianum strains are potential CMCase and β-glucosidase producers. However, few researches have been reported on cellulase production by T. harzianum and the subsequent use of the crude cellulase for cellulose enzymatic hydrolysis. For cellulose hydrolysis to be efficiently performed, the presence of the whole set of cellulase components including exoglucanase, endoglucanase, and β-glucosidase at a considerable concentration is required. Biomass recalcitrance is also a bottleneck in the bioconversion of agricultural residues to value-added products. An effective pretreatment could be of central significance in the bioconversion of biomass to biofuels.
Fulltext Citation Classics on Dental Caries: A Systematic Review

Arshad AI, Ahmad P, Dummer PMH, Alam MK, Asif JA, Mahmood Z, et al.

Eur J Dent, 2020 Feb;14(1):128-143.
PMID: 32189321 DOI: 10.1055/s-0040-1703419

OBJECTIVE: A systematic search was performed for the identification and analysis of the 100 most often cited articles on dental caries and to highlight the changing trends in the field of dentistry over time.
MATERIALS AND METHODS: The search was performed without any restriction on the study design, publication year, or language using the Web of Science (WoS) group of Clarivate Analytics enabling the search through "All Databases." Based on the citation count as available in WoS, the articles were sorted in a descending manner. Information regarding each article was then extracted, which included its authorship, counts of citation (in other databases), citation density, current citation index (2019), publication year, country of publication, journal of article, evidence level based on study design, and keywords description.
RESULTS: The count of citation for each article varied in each database, that is, 175 to 2,003 in WoS, 89 to 1,981 in Scopus, and 126 to 3,492 when searched in Google Scholar. The highest number of articles (n = 10) related to dental caries were published in 2004. A total of 301 authors made valuable contributions to this field, out of which J.D. Featherstone had coauthored 6 articles. A significant negative correlation (p < 0.01) was found between the age of the article and the citation density (r =-0.545). However, a nonsignificant correlation (p = 0.952) occurred between the age of publication and the citation count (r = 0.006).
CONCLUSION: The results of this systematic review provide a critical appraisal of the context underpinning scientific developments in the field of dental caries and also highlighted trends in clinical management and research.
Helicobacter pylori eradication with short-term therapy leads to duodenal ulcer healing without the need for continued acid suppression therapy

Goh KL, Navaratnam P, Peh SC, Wong NW, Chuah SY, Rahman NA, et al.

Eur J Gastroenterol Hepatol, 1996 May;8(5):421-3.
PMID: 8804868

To determine whether duodenal ulcers continue to heal following successful Helicobacter pylori eradication with short-term eradication therapy without further acid suppression therapy.
Recent advances in celluloses and their hybrids for stimuli-responsive drug delivery

Sampath Udeni Gunathilake TM, Ching YC, Chuah CH, Rahman NA, Liou NS

Int J Biol Macromol, 2020 May 07;158:670-688.
PMID: 32389655 DOI: 10.1016/j.ijbiomac.2020.05.010

The limitations of existing drug delivery systems (DDS) such as non-specific bio-distribution and poor selectivity have led to the exploration of a variety of carrier platforms to facilitate highly desirable and efficient drug delivery. Stimuli-responsive DDS are one of the most versatile and innovative approach to steer the compounds to the intended sites by exploiting their responsiveness to a range of various triggers. Preparation of stimuli-responsive DDS using celluloses and their derivatives offer a remarkable advantage over conventional polymer materials. In this review, we highlight on state-of-art progress in developing cellulose/cellulose hybrid stimuli-responsive DDS, which covers the preparation techniques, physicochemical properties, basic principles and, mechanisms of stimuli effect on drug release from various types of cellulose based carriers, through recent innovative investigations. Attention has been paid to endogenous stimuli (pH, temperature, redox gradient and ionic-strength) responsive DDS and exogenous stimuli (light, magnetic field and electric field) responsive DDS, where the cellulose-based materials have been extensively employed. Furthermore, the current challenges and future prospects of these DDS are also discussed at the end.
Fulltext Dynamics and binding interactions of peptide inhibitors of dengue virus entry

Isa DM, Chin SP, Chong WL, Zain SM, Rahman NA, Lee VS

J Biol Phys, 2019 03;45(1):63-76.
PMID: 30680580 DOI: 10.1007/s10867-018-9515-6

In this study, we investigate the binding interactions of two synthetic antiviral peptides (DET2 and DET4) on type II dengue virus (DENV2) envelope protein domain III. These two antiviral peptides are designed based on the domain III of the DENV2 envelope protein, which has shown significant inhibition activity in previous studies and can be potentially modified further to be active against all dengue strains. Molecular docking was performed using AutoDock Vina and the best-ranked peptide-domain III complex was further explored using molecular dynamics simulations. Molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) was used to calculate the relative binding free energies and to locate the key residues of peptide-protein interactions. The predicted binding affinity correlated well with the previous experimental studies. DET4 outperformed DET2 and is oriented within the binding site through favorable vdW and electrostatic interactions. Pairwise residue decomposition analysis has revealed several key residues that contribute to the binding of these peptides. Residues in DET2 interact relatively lesser with the domain III compared to DET4. Dynamic cross-correlation analysis showed that both the DET2 and DET4 trigger different dynamic patterns on the domain III. Correlated motions were seen between the residue pairs of DET4 and the binding site while binding of DET2 results in anti-correlated motion on the binding site. This work showcases the use of computational study in elucidating and explaining the experiment observation on an atomic level.
Fulltext Molecular Dynamics Simulations in Designing DARPins as Phosphorylation-Specific Protein Binders of ERK2

Gautam V, Nimmanpipug P, Zain SM, Rahman NA, Lee VS

Molecules, 2021 Jul 27;26(15).
PMID: 34361694 DOI: 10.3390/molecules26154540

Extracellular signal-regulated kinases 1 and 2 (ERK1/2) play key roles in promoting cell survival and proliferation through the phosphorylation of various substrates. Remarkable antitumour activity is found in many inhibitors that act upstream of the ERK pathway. However, drug-resistant tumour cells invariably emerge after their use due to the reactivation of ERK1/2 signalling. ERK1/2 inhibitors have shown clinical efficacy as a therapeutic strategy for the treatment of tumours with mitogen-activated protein kinase (MAPK) upstream target mutations. These inhibitors may be used as a possible strategy to overcome acquired resistance to MAPK inhibitors. Here, we report a class of repeat proteins-designed ankyrin repeat protein (DARPin) macromolecules targeting ERK2 as inhibitors. The structural basis of ERK2-DARPin interactions based on molecular dynamics (MD) simulations was studied. The information was then used to predict stabilizing mutations employing a web-based algorithm, MAESTRO. To evaluate whether these design strategies were successfully deployed, we performed all-atom, explicit-solvent molecular dynamics (MD) simulations. Two mutations, Ala → Asp and Ser → Leu, were found to perform better than the original sequence (DARPin E40) based on the associated energy and key residues involved in protein-protein interaction. MD simulations and analysis of the data obtained on these mutations supported our predictions.
Fulltext Adult female with acute renal failure and weight loss

Abdul-Rahman NA, Azman RR, Kumar G

Saudi Med J, 2016 May;37(5):584-6.
PMID: 27146625 DOI: 10.15537/smj.2016.5.15042
Fulltext Incorporation of Hydroxyapatite into Glass Ionomer Cement (GIC) Formulated Based on Alumino-Silicate-Fluoride Glass Ceramics from Waste Materials

Wan Jusoh WN, Matori KA, Mohd Zaid MH, Zainuddin N, Ahmad Khiri MZ, Abdul Rahman NA, et al.

Materials (Basel), 2021 Feb 18;14(4).
PMID: 33670465 DOI: 10.3390/ma14040954

Glass ionomer cement (GIC) is a well-known restorative material applied in dentistry. The present work aims to study the effect of hydroxyapatite (HA) addition into GIC based on physical, mechanical and structural properties. The utilization of waste materials namely clam shell (CS) and soda lime silica (SLS) glass as replacements for the respective CaO and SiO2 sources in the fabrication of alumino-silicate-fluoride (ASF) glass ceramics powder. GIC was formulated based on ASF glass ceramics, polyacrylic acid (PAA) and deionized water, while 1 wt.% of HA powder was added to enhance the properties of the cement samples. The cement samples were subjected to four different ageing times before being analyzed. In this study, the addition of HA caused an increment in density and compressive strength results along with ageing time. Besides, X-ray Diffraction (XRD) revealed the formation of fluorohydroxyapatite (FHA) phase in HA-added GIC samples and it was confirmed by Fourier Transform Infrared (FTIR) analysis which detected OH‒F vibration mode. In addition, needle-like and agglomeration of spherical shapes owned by apatite crystals were observed from Field Emission Scanning Electron Microscopy (FESEM). Based on Energy Dispersive X-ray (EDX) analysis, the detection of chemical elements in the cement samples were originated from chemical compounds used in the preparation of glass ceramics powder and also the polyacid utilized in initiating the reaction of GIC.
Fulltext Synthesis and characterizations of o-nitrochitosan based biopolymer electrolyte for electrochemical devices

Rahman NA, Abu Hanifah S, Mobarak NN, Su'ait MS, Ahmad A, Shyuan LK, et al.

PLoS One, 2019;14(2):e0212066.
PMID: 30768616 DOI: 10.1371/journal.pone.0212066

For the past decade, much attention was focused on polysaccharide natural resources for various purposes. Throughout the works, several efforts were reported to prepare new function of chitosan by chemical modifications for renewable energy, such as fuel cell application. This paper focuses on synthesis of the chitosan derivative, namely, O-nitrochitosan which was synthesized at various compositions of sodium hydroxide and reacted with nitric acid fume. Its potential as biopolymer electrolytes was studied. The substitution of nitro group was analyzed by using Attenuated Total Reflectance Fourier Transform Infra-Red (ATR-FTIR) analysis, Nuclear Magnetic Resonance (NMR) and Elemental Analysis (CHNS). The structure was characterized by X-ray Diffraction (XRD) and its thermal properties were examined by using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Whereas, the ionic conductivity of the samples was analyzed by electrochemical impedance spectroscopy (EIS). From the IR spectrum results, the nitro group peaks of O-nitrochitosan, positioned at 1646 and 1355 cm-1, were clearly seen for all pH media. At pH 6, O-nitrochitosan exhibited the highest degree of substitution at 0.74 when analyzed by CHNS analysis and NMR further proved that C-6 of glucosamine ring was shifted to the higher field. However, the thermal stability and glass transition temperatures were decreased with acidic condition. The highest ionic conductivity of O-nitrochitosan was obtained at ~10-6 cm-1. Overall, the electrochemical property of new O-nitrochitosan showed a good improvement as compared to chitosan and other chitosan derivatives. Hence, O-nitrochitosan is a promising biopolymer electrolyte and has the potential to be applied in electrochemical devices.
Fulltext Distribution of Flavonoids and Cyclohexenyl Chalcone Derivatives in Conventional Propagated and In Vitro-Derived Field-Grown Boesenbergia rotunda (L.) Mansf

Tan BC, Tan SK, Wong SM, Ata N, Rahman NA, Khalid N

Evid Based Complement Alternat Med, 2015;2015:451870.
PMID: 25883671 DOI: 10.1155/2015/451870

The distribution patterns of flavonoids and cyclohexenyl chalcone derivatives in conventional propagated (CP) and in vitro-derived (CPA) field-grown plants of an important medicinal ginger, Boesenbergia rotunda, are described. A total of eight compounds were extracted from six organs (rootlet, rhizome, shoot base, maroon stem, stalk, and leaf) of the CP and CPA plants. Five major chromatographic peaks, namely, alpinetin, pinocembrin, pinostrobin, 4-hydroxypanduratin A, and panduratin A, were consistently observed by high performance liquid chromatography. Nonaerial organs had higher levels of flavonoids than the aerial ones for all types of samples. Among the compounds detected, pinostrobin and 4-hydroxypanduratin A were the most abundant flavonoid and cyclohexenyl chalcone derivative, respectively. The distribution and abundance of the bioactive compounds suggested that the shoot base could be more potentially useful for medicinal application than other organs of the plant and may be the site of storage or occurrence of biosynthetic enzymatic activities.

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