Displaying publications 41 - 60 of 166 in total

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  1. 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.

  2. Mohd Yusof H, Mohamad R, Zaidan UH, Rahman NA
    Microb Cell Fact, 2020 Jan 15;19(1):10.
    PMID: 31941498 DOI: 10.1186/s12934-020-1279-6
    BACKGROUND: The use of microorganisms in the biosynthesis of zinc oxide nanoparticles (ZnO NPs) has recently emerged as an alternative to chemical and physical methods due to its low-cost and eco-friendly method. Several lactic acid bacteria (LAB) have developed mechanisms in tolerating Zn2+ through prevention against their toxicity and the production of ZnO NPs. The LAB's main resistance mechanism to Zn2+ is highly depended on the microorganisms' ability to interact with Zn2+ either through biosorption or bioaccumulation processes. Besides the inadequate studies conducted on biosynthesis with the use of zinc-tolerant probiotics, the understanding regarding the mechanism involved in this process is not clear. Therefore, this study determines the features of probiotic LAB strain TA4 related to its resistance to Zn2+. It also attempts to illustrate its potential in creating a sustainable microbial cell nanofactory of ZnO NPs.

    RESULTS: A zinc-tolerant probiotic strain TA4, which was isolated from local fermented food, was selected based on the principal component analysis (PCA) with the highest score of probiotic attributes. Based on the 16S rRNA gene analysis, this strain was identified as Lactobacillus plantarum strain TA4, indicating its high resistance to Zn2+ at a maximum tolerable concentration (MTC) value of 500 mM and its capability of producing ZnO NPs. The UV-visible spectroscopy analysis proved the formations of ZnO NPs through the notable absorption peak at 380 nm. It was also found from the dynamic light scattering (DLS) analysis that the Z-average particle size amounted to 124.2 nm with monodisperse ZnO NPs. Studies on scanning electron microscope (SEM), energy-dispersive X-ray (EDX) spectroscopy, and Fourier-transform infrared spectroscopy (FT-IR) revealed that the main mechanisms in ZnO NPs biosynthesis were facilitated by the Zn2+ biosorption ability through the functional groups present on the cell surface of strain TA4.

    CONCLUSIONS: The strong ability of zinc-tolerant probiotic of L. plantarum strain TA4 to tolerate high Zn2+ concentration and to produce ZnO NPs highlights the unique properties of these bacteria as a natural microbial cell nanofactory for a more sustainable and eco-friendly practice of ZnO NPs biosynthesis.

  3. Ahmad R, Rahman NA, Hasan R, Yaacob NS, Ali SH
    Spec Care Dentist, 2020 Jan;40(1):62-70.
    PMID: 31774579 DOI: 10.1111/scd.12436
    AIMS: To investigate the oral health and nutritional status of children with cerebral palsy (CP).

    METHODS AND RESULTS: Oral health assessment included dental caries and dental plaque maturity scores (DPMS) while the nutritional assessment included children's height-for-age Z-score (HAZ), body mass index-for-age Z-score (BAZ), mid-upper-arm circumference (MUAC), nutrient intake, cariogenic food frequency (CFF) and daily sugar exposure (DSE). Ninety-three CP children were recruited. The prevalence of caries was 81.7% (95% CI: 72.7%-88.3%). The median (IQR) of the DMFT and dft scores were 0.5(4.0) and 3.0(8.0), respectively. Most of the participants had acid-producing plaque (90.3%), severely stunted (81.4%), and 45% were severely thin with acute malnutrition. Intakes of calcium, iron, zinc, vitamin A, vitamin D and total fat were below 77% of the Recommended Nutrient Intakes for Malaysian children (RNI 2017). Nine types of cariogenic foods/drinks were consumed moderately, and DSE indicated that 45% of the children were at moderate risk of dental caries.

    CONCLUSION: Untreated dental caries, severe stunting and thinness were prevalent, and cariogenic foods/drinks were consumed moderately suggesting a moderate risk of caries. Therefore, controlling cariogenic food intake is crucial, but monitoring daily nutrient intake is needed for the optimum growth of children with CP.

  4. Pasupuleti VR, Arigela CS, Gan SH, Salam SKN, Krishnan KT, Rahman NA, et al.
    Oxid Med Cell Longev, 2020;2020:8878172.
    PMID: 33299532 DOI: 10.1155/2020/8878172
    Despite the availability of various antidiabetic drugs, diabetes mellitus (DM) remains one of the world's most prevalent chronic diseases and is a global burden. Hyperglycaemia, a characteristic of type 2 diabetes mellitus (T2DM), substantially leads to the generation of reactive oxygen species (ROS), triggering oxidative stress as well as numerous cellular and molecular modifications such as mitochondrial dysfunction affecting normal physiological functions in the body. In mitochondrial-mediated processes, oxidative pathways play an important role, although the responsible molecular mechanisms remain unclear. The impaired mitochondrial function is evidenced by insulin insensitivity in various cell types. In addition, the roles of master antioxidant pathway nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)/antioxidant response elements (ARE) are being deciphered to explain various molecular pathways involved in diabetes. Dietary factors are known to influence diabetes, and many natural dietary factors have been studied to improve diabetes. Honey is primarily rich in carbohydrates and is also abundant in flavonoids and phenolic acids; thus, it is a promising therapeutic antioxidant for various disorders. Various research has indicated that honey has strong wound-healing properties and has antibacterial, anti-inflammatory, antifungal, and antiviral effects; thus, it is a promising antidiabetic agent. The potential antidiabetic mechanisms of honey were proposed based on its major constituents. This review focuses on the various prospects of using honey as an antidiabetic agent and the potential insights.
  5. Rahman NA, Katayama T, Wahid MEA, Kasan NA, Khatoon H, Yamada Y, et al.
    Front Bioeng Biotechnol, 2020;8:581628.
    PMID: 33330417 DOI: 10.3389/fbioe.2020.581628
    Antioxidants found in microalgae play an essential role in both animals and humans, against various diseases and aging processes by protecting cells from oxidative damage. In this study, 26 indigenous tropical marine microalgae were screened. Out of the 26 screened strains, 10 were selected and were further investigated for their natural antioxidant compounds which include carotenoids, phenolics, and fatty acids collected in their exponential and stationary phases. The antioxidant capacity was also evaluated by a total of four assays, which include ABTS, DPPH, superoxide radical (O2•-) scavenging capacity, and nitric oxide (•NO-) scavenging capacity. This study revealed that the antioxidant capacity of the microalgae varied between divisions, strains, and growth phase and was also related to the content of antioxidant compounds present in the cells. Carotenoids and phenolics were found to be the major contributors to the antioxidant capacity, followed by polyunsaturated fatty acids linoleic acid (LA), eicosapentaenoic acid (EPA), arachidonic acid (ARA), and docosahexaenoic acid (DHA) compared to other fatty acids. The antioxidant capacity of the selected bacillariophytes and haptophytes was found to be positively correlated to phenolic (R2-value = 0.623, 0.714, and 0.786 with ABTS, DPPH, and •NO-) under exponential phase, and to carotenoid fucoxanthin and β-carotene (R2 value = 0.530, 0.581 with ABTS, and 0.710, 0.795 with O2•-) under stationary phase. Meanwhile, antioxidant capacity of chlorophyte strains was positively correlated with lutein, β-carotene and zeaxanthin under the exponential phase (R2 value = 0.615, 0.615, 0.507 with ABTS, and R2 value = 0.794, 0.659, and 0.509 with •NO-). In the stationary phase, chlorophyte strains were positively correlated with violaxanthin (0.755 with •NO-), neoxanthin (0.623 with DPPH, 0.610 with •NO-), and lutein (0.582 with •NO-). This study showed that antioxidant capacity and related antioxidant compound production of tropical microalgae strains are growth phase-dependent. The results can be used to improve the microalgal antioxidant compound production for application in pharmaceutical, nutraceutical, food, and feed industry.
  6. Roslan MAM, Zulkifli NN, Sobri ZM, Zuan ATK, Cheak SC, Abdul Rahman NA
    PLoS One, 2020;15(7):e0232860.
    PMID: 32645001 DOI: 10.1371/journal.pone.0232860
    Limited information is available that seed biopriming with plant growth-promoting Enterobacter spp. play a prominent role to enhance vegetative growth of plants. Contrary to Enterobacter cloacae, Enterobacter hormaechei is a less-studied counterpart despite its vast potential in plant growth-promotion mainly through the inorganic phosphorus (P) and potassium (K) solubilization abilities. To this end, 18 locally isolated bacterial pure cultures were screened and three strains showed high P- and K-solubilizing capabilities. Light microscopy, biochemical tests and 16S rRNA gene sequencing revealed that strains 15a1 and 40a were closely related to Enterobacter hormaechei while strain 38 was closely related to Enterobacter cloacae (Accession number: MN294583; MN294585; MN294584). All Enterobacter spp. shared common plant growth-promoting traits, namely nitrogen (N2) fixation, indole-3-acetic acid production and siderophore production. The strains 38 and 40a were able to produce gibberellic acid, while only strain 38 was able to secrete exopolysaccharide on agar. Under in vitro germination assay of okra (Abelmoschus esculentus) seeds, Enterobacter spp. significantly improved overall germination parameters and vigor index (19.6%) of seedlings. The efficacy of root colonization of Enterobacter spp. on the pre-treated seedling root tips was confirmed using Scanning Electron Microscopy (SEM). The pot experiment of bioprimed seeds of okra seedling showed significant improvement of the plant growth (> 28%) which corresponded to the increase of P and K uptakes (> 89%) as compared to the uninoculated control plants. The leaf surface area and the SPAD chlorophyll index of bioprimed plants were increased by up to 29% and 9% respectively. This report revealed that the under-explored species of P- and K-solubilizing Enterobacter hormaechei sp. with multiple plant beneficial traits presents a great potential sustainable approach for enhancement of soil fertility and P and K uptakes of plants.
  7. Abdullah AA, Lee YK, Chin SP, Lim SK, Lee VS, Othman R, et al.
    Curr Med Chem, 2020;27(30):4945-5036.
    PMID: 30514185 DOI: 10.2174/0929867326666181204155336
    To date, there is still no approved anti-dengue agent to treat dengue infection in the market. Although the only licensed dengue vaccine, Dengvaxia is available, its protective efficacy against serotypes 1 and 2 of dengue virus was reported to be lower than serotypes 3 and 4. Moreover, according to WHO, the risk of being hospitalized and having severe dengue increased in seronegative individuals after they received Dengvaxia vaccination. Nevertheless, various studies had been carried out in search of dengue virus inhibitors. These studies focused on the structural (C, prM, E) and non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) of dengue virus as well as host factors as drug targets. Hence, this article provides an overall up-to-date review of the discovery of dengue virus inhibitors that are only targeting the structural and non-structural viral proteins as drug targets.
  8. Liew YJM, Lee YK, Khalid N, Rahman NA, Tan BC
    PeerJ, 2020;8:e9094.
    PMID: 32391211 DOI: 10.7717/peerj.9094
    Flavonoids and prenylated flavonoids are active components in medicinal plant extracts which exhibit beneficial effects on human health. Prenylated flavonoids consist of a flavonoid core with a prenyl group attached to it. This prenylation process is catalyzed by prenyltranferases (PTs). At present, only a few flavonoid-related PT genes have been identified. In this study, we aimed to investigate the roles of PT in flavonoid production. We isolated a putative PT gene (designated as BrPT2) from a medicinal ginger, Boesenbergia rotunda. The deduced protein sequence shared highest gene sequence homology (81%) with the predicted homogentisate phytyltransferase 2 chloroplastic isoform X1 from Musa acuminata subsp. Malaccensis. We then cloned the BrPT2 into pRI vector and expressed in B. rotunda cell suspension cultures via Agrobacterium-mediated transformation. The BrPT2-expressing cells were fed with substrate, pinostrobin chalcone, and their products were analyzed by liquid chromatography mass spectrometry. We found that the amount of flavonoids, namely alpinetin, pinostrobin, naringenin and pinocembrin, in BrPT2-expressing cells was higher than those obtained from the wild type cells. However, we were unable to detect any targeted prenylated flavonoids. Further in-vitro assay revealed that the reaction containing the BrPT2 protein produced the highest accumulation of pinostrobin from the substrate pinostrobin chalcone compared to the reaction without BrPT2 protein, suggesting that BrPT2 was able to accelerate the enzymatic reaction. The finding of this study implied that the isolated BrPT2 may not be involved in the prenylation of pinostrobin chalcone but resulted in high yield and production of other flavonoids, which is likely related to enzyme promiscuous activities.
  9. Omar F, Ab-Ghani Z, Rahman NA, Halim MS
    Eur J Dent, 2019 Oct;13(4):589-598.
    PMID: 31891975 DOI: 10.1055/s-0039-1700659
    OBJECTIVES:  This study evaluates the efficacy and safety of the professionally prescribed and nonprescription over-the-counter (OTC) bleaching agents.

    MATERIALS AND: METHODS:  Extracted human upper central incisors were prepared and stained with red wine for 14 days before being subjected to four different bleaching agents: professionally prescribed opalescence PF 15%, VOCO Perfect Bleach 10%, nonprescription OTC Crest 3D Whitestrips, and Whitelight Teeth Whitening System. Colorimetric measurement was performed with Vita Easyshade Handheld Spectrophotometer, enamel surface microhardness measured using Vickers Hardness machine, and surface roughness was evaluated with profilometer, before and after bleaching. Scanning electron microscope (SEM) evaluation and atomic force microscopy were conducted postbleaching.

    STATISTICAL ANALYSIS:  The data were analyzed with t-test, two-way ANOVA, one-way ANOVA, and Turkey's test at a significance level of 5%.

    RESULTS:  All bleaching products have the same efficacy to whiten stained enamel. Opalescence PF 15% showed significant increase in the microhardness (92.69 ± 68.316). All groups demonstrated significant increase in surface roughness (p < 0.05). SEM evaluation showed that Opalescence PF 15% resulted in same microscopic appearance as unbleached enamel, while VOCO Perfect Bleach 10%, Whitelight Teeth Whitening System and Crest 3D Whitestrips demonstrated mild to moderate irregularities and accentuated irregularities, respectively.

    CONCLUSION:  Professionally prescribed bleaching agent of Opalescence PF 15% is effective tin whitening the teeth, while the other bleaching products may be effective but also have deleterious effects on the enamel.

  10. James JG, Izam AS, Nabil S, Rahman NA, Ramli R
    J Craniofac Surg, 2019 8 27;31(1):e22-e26.
    PMID: 31449209 DOI: 10.1097/SCS.0000000000005812
    AIM: The objective of this review was to determine the different types of surgical intervention in the management of nasal bone fractures, the outcomes, and complications associated with each intervention.

    METHODS: A search was conducted using the PubMed and Cochrane Database of Systematic Review databases from January 1, 1997 until September 9, 2017. The search strategy was constructed using the Population Intervention Comparison Outcome framework with keywords related to nasal fracture and its treatment. Two sets of independent researchers performed the analysis. Qualitative analysis was performed using the Methodological Index for Non-Randomized Studies and National Institute for Clinical Excellence methodology for randomized controlled trial checklists.

    RESULTS: The 4276 titles were obtained from PubMed database alone. Exclusion was made based on the title, abstract and full-text analysis. Finally, 23 papers were included and analyzed. Of the 23 papers, 13 (56.5%) were retrospective record review, 2 (8.7%) were randomized clinical trial or a randomized study and 8 case series (34.8%). 16 (69.6%) studies addressed closed reduction, 3 studies (13%) on open reduction and 4 studies (17.4%) addressed both open and closed reduction. The main focus in the outcome in all studies was accuracy of the anatomical reduction of the nasal bones. Three studies (13.0%) reported restoration of function such as breathing comfort or release in respiratory obstruction and another 3 (13.0%) addressed both cosmetic and breathing outcomes. Residual deformity was the most described complications in the studies (30.4%). In general, most of the studies were not of high quality as they lacked in some key elements in the Methodological Index for Non-Randomized Studies checklist.

    CONCLUSION: Both closed and open reduction provided good outcomes in cosmetic and breathing. Septoplasty is recommended to be performed simultaneously with fracture reduction.

  11. Ahmed T, Rahman NA, Alam MK
    Prog Orthod, 2019 Jul 08;20(1):26.
    PMID: 31281954 DOI: 10.1186/s40510-019-0277-x
    BACKGROUND: To introduce an orthodontic bracket debonding device capable of measuring debonding force clinically by a novel sensor mechanism MATERIALS AND METHOD: A prototype orthodontic debonding device was constructed utilizing a lift-off debonding instrument (LODI) and force-sensitive resistor (FSR). For data interpretation, the force sensor was equipped with a microcontroller and C++ programming software running on a computer. Ninety-nine (99) 0.022-in. conventional metallic brackets were bonded to premolar teeth in vitro by a single clinician applying the same adhesive and bonding technique. For validation, the mean debonding force measured by the prototype debonding device (n = 30) and the universal testing machine (n = 30) was compared. Both intra- and inter-examiner reliability tests were done by holding and operating the device in a standardized manner. Following debonding by the prototype device, the bracket failure pattern was evaluated (n = 30) by adhesive remnant index (ARI) under the stereomicroscope at × 30 magnification. Statistical analysis included independent samples t test for validation and intraclass correlation coefficient (ICC) with a 95% confidence interval for both intra- and inter-examiner reliability.

    RESULTS: Mean orthodontic bracket debonding force measured by the prototype device (9.36 ± 1.65 N) and the universal testing machine (10.43 ± 2.71 N) was not significantly different (p 

  12. 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.
  13. Dabbagh A, Hedayatnasab Z, Karimian H, Sarraf M, Yeong CH, Madaah Hosseini HR, et al.
    Int J Hyperthermia, 2019;36(1):104-114.
    PMID: 30428737 DOI: 10.1080/02656736.2018.1536809
    PURPOSE: Although magnetite nanoparticles (MNPs) are promising agents for hyperthermia therapy, insufficient drug encapsulation efficacies inhibit their application as nanocarriers in the targeted drug delivery systems. In this study, porous magnetite nanoparticles (PMNPs) were synthesized and coated with a thermosensitive polymeric shell to obtain a synergistic effect of hyperthermia and chemotherapy.

    MATERIALS AND METHODS: PMNPs were produced using cetyltrimethyl ammonium bromide template and then coated by a polyethylene glycol layer with molecular weight of 1500 Da (PEG1500) and phase transition temperature of 48 ± 2 °C to endow a thermosensitive behavior. The profile of drug release from the nanostructure was studied at various hyperthermia conditions generated by waterbath, magnetic resonance-guided focused ultrasound (MRgFUS), and alternating magnetic field (AMF). The in vitro cytotoxicity and hyperthermia efficacy of the doxorubicin-loaded nanoparticles (DOX-PEG1500-PMNPs) were assessed using human lung adenocarcinoma (A549) cells.

    RESULTS: Heat treatment of DOX-PEG1500-PMNPs containing 235 ± 26 mg·g-1 DOX at 48 °C by waterbath, MRgFUS, and AMF, respectively led to 71 ± 4%, 48 ± 3%, and 74 ± 5% drug release. Hyperthermia treatment of the A549 cells using DOX-PEG1500-PMNPs led to 77% decrease in the cell viability due to the synergistic effects of magnetic hyperthermia and chemotherapy.

    CONCLUSION: The large pores generated in the PMNPs structure could provide a sufficient space for encapsulation of the chemotherapeutics as well as fast drug encapsulation and release kinetics, which together with thermosensitive characteristics of the PEG1500 shell, make DOX-PEG1500-PMNPs promising adjuvants to the magnetic hyperthermia modality.

  14. Murthy S, Hazli UHAM, Kong KW, Mai CW, Leong CO, Rahman NA, et al.
    Curr Org Synth, 2019;16(8):1166-1173.
    PMID: 31984923 DOI: 10.2174/1570179416666191003095253
    BACKGROUND: Sesamol is a widely used antioxidant for the food and pharmaceutical industries. The oxidation products of this compound may be accumulated in foods or ingested. Little is known about its effect on human health.

    OBJECTIVE: It is of great interest to identify the oxidation products of sesamol that may be beneficial to humans. This study was undertaken to identify the oxidation products of sesamol and investigate their antioxidant and cytotoxic activities.

    MATERIALS AND METHODS: Using the ferricyanide oxidation approach, four oxidation products of sesamol (2, 3, 20 & 21) have been identified. Structural elucidation of these compounds was established on the basis of their detailed NMR spectroscopic analysis, mass spectrometry and x-ray crystallography. Additionally, a formation mechanism of compound 20 was proposed based on high-resolution mass spectrometry-fragmentation method. The antioxidant activities of these compounds were determined by the DPPH, FRAP, and ABTS assays. The in vitro antiproliferative activity of these compounds was evaluated against a panel of human cancer cell lines as well as non-cancerous cells.

    RESULTS: Two oxidation products of sesamol were found to contain an unusual methylenedioxy ring-opening skeleton, as evidenced by spectroscopic and x-ray crystallographic data. Among all compounds, 20 displayed impressive antiproliferative activities against a panel of human cancer cell lines yet remained non-toxic to noncancerous cells. The antioxidant activities of compound 20 are significantly weaker than sesamol as determined by the DPPH, FRAP, and ABTS assays.

    CONCLUSION: The oxidation products of sesamol could be a valuable source of bioactive molecules. Compound 20 may be used as a potential lead molecule for cancer studies.

  15. 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.
  16. Mohd Yusof H, Mohamad R, Zaidan UH, Abdul Rahman NA
    PMID: 31321032 DOI: 10.1186/s40104-019-0368-z
    In recent years, zinc oxide nanoparticles (ZnO NPs) have gained tremendous attention attributed to their unique properties. Notably, evidence has shown that zinc is an important nutrient in living organisms. As such, both prokaryotes and eukaryotes including bacteria, fungi and yeast are exploited for the synthesis of ZnO NPs by using microbial cells or enzyme, protein and other biomolecules compounds in either an intracellular or extracellular route. ZnO NPs exhibit antimicrobial properties, however, the properties of nanoparticles (NPs) are depended upon on their size and shape, which make them specific for various applications. Nevertheless, the desired size and shape of NPs can be obtained through the optimization process of microbes mediated synthesis by manipulating their reaction conditions. It should be noted that ZnO NPs are synthesized by various chemical and physical methods. Nonetheless, these methods are expensive and not environmentally friendly. On that account, the microbes mediated synthesis of ZnO NPs have rapidly evolved recently where the microbes are cleaner, eco-friendly, non-toxic and biocompatible as the alternatives to chemical and physical practices. Moreover, zinc in the form of NPs is more effective than their bulk counterparts and thus, they have been explored for many potential applications including in animals industry. Notably, with the advent of multi-drug resistant strains, ZnO NPs have emerged as the potential antimicrobial agents. This is mainly due to their superior properties in combating a broad spectrum of pathogens. Moreover, zinc is known as an essential trace element for most of the biological function in the animal's body. As such, the applications of ZnO NPs have been reported to significantly enhance the health and production of the farm animals. Thus, this paper reviews the biological synthesis of ZnO NPs by the microbes, the mechanisms of the biological synthesis, parameters for the optimization process and their potential application as an antimicrobial agent and feed supplement in the animal industry as well as their toxicological hazards on animals.
  17. Abduraman MA, Hariono M, Yusof R, Rahman NA, Wahab HA, Tan ML
    Heliyon, 2018 Dec;4(12):e01023.
    PMID: 30560214 DOI: 10.1016/j.heliyon.2018.e01023
    Background: Dengue infection is an endemic infectious disease and it can lead to dengue fever, dengue hemorrhagic fever, and/or dengue shock syndromes. Dengue NS2B/NS3 protease complex is essential for viral replication and is a primary target for anti-dengue drug development. In this study, a NS2B/NS3 protease inhibition assay was developed using AlphaScreen® beads and was used to screen compounds for their protease inhibition activities.

    Methods: The assay system utilized a known NS2B/NS3 peptide substrate, a recombinant of NS2B/NS3 protease with proprietary StrepTactin® donor and nickel chelate acceptor beads in 384-well format.

    Results: The optimized assay to screen for NS2B/NS3 protease inhibitors was demonstrated to be potentially useful with reasonable z' factor, coefficient variance and signal to background ratio. However, screening of synthesized thioguanine derivatives using the optimized AlphaScreen® assay revealed weak NS2B/NS3 inhibition activities.

    Conclusion: The AlphaScreen® assay to screen for NS2B/NS3 protease inhibitors is potentially applicable for high throughput screening.

  18. Alhajj N, Chee CF, Wong TW, Rahman NA, Abu Kasim NH, Colombo P
    Expert Opin Drug Deliv, 2018 12;15(12):1223-1247.
    PMID: 30422017 DOI: 10.1080/17425247.2018.1547280
    INTRODUCTION: Pulmonary drug delivery is organ-specific and benefits local drug action for lung cancer. The use of nanotechnology and targeting ligand enables cellular-specific drug action. Combination approaches increase therapeutic efficacy and reduce adverse effects of cancer chemotherapeutics that have narrow therapeutic index window and high cytotoxicity levels. The current progress of inhaled cancer chemotherapeutics has not been examined with respect to targeting strategy and clinical application potential.

    AREAS COVERED: This review examines the state of the art in passive (processing and formulation) and active (targeting ligand and receptor binding) technologies in association with the use of nanocarrier to combat lung cancer. It highlights routes to equip nanocarrier with targeting ligands as a function of the chemistry of participating biomolecules and challenges in inhalational nanoproduct development and clinical applications. Both research and review articles were examined using the Scopus, Elsevier, Web of Science, Chemical Abstracts, Medline, CASREACT, CHEMCATS, and CHEMLIST database with the majority of information retrieved between those of 2000-2018.

    EXPERT COMMENTARY: The therapeutic efficacy of targeting ligand-decorated nanocarriers needs to be demonstrated in vivo in the form of finished inhalational products. Their inhalation efficiency and medical responses require further examination. Clinical application of inhaled nanocancer chemotherapeutics is premature.

  19. Ahmed T, Rahman NA, Alam MK
    Eur J Dent, 2018 10 30;12(4):602-609.
    PMID: 30369810 DOI: 10.4103/ejd.ejd_22_18
    The aim of this study was to systematically review the available studies measuring the bond strength of orthodontic bracket-adhesive system under different experimental conditions in vivo. Literature search was performed in four different databases: PubMed, Web of Science, Cochrane, and Scopus using the keywords - bond strength, orthodontic brackets, bracket-adhesive, and in vivo. A total of six full-text articles were selected based on the inclusion and exclusion criteria of our study after a careful assessment by the two independent reviewers. Data selection was performed by following PRISMA 2009 guidelines. Five of the selected studies were clinical trials; one study was a randomized clinical trial. From each of the selected articles, the following data were extracted - number of samples, with the type of tooth involved materials under experiment methods of measurement, the time interval between bonding and debonding orthodontic brackets, mode of force application, and the bond strength results with the overall outcome. The methodological quality assessment of each article was done by the modified Downs and Black checklist method. The qualitative analyses were done by two independent reviewers. Conflicting issues were resolved in a consensus meeting by consulting the third reviewer (MKA). Meta-analysis could not be performed due to the lack of homogenous study results. The review reached no real conclusion apart from the lack of efforts to clinically evaluate the bonding efficiency of a wide range of orthodontic bracket-adhesive systems in terms of debonding force compared to laboratory-based in vitro and ex vivo studies.
  20. Salim NA, Muttlib NAA, Alawi R, Rahman NA, Ariffin Z
    Acta Stomatol Croat, 2018 Sep;52(3):218-226.
    PMID: 30510297 DOI: 10.15644/asc52/3/5
    Objective: This study aimed to compare the difference in marginal dye penetration between everStick, Parapost XP, Parapost fiber white and control groups under gradual loading.

    Materials and Methods: Sixty-eight human maxillary permanent incisors were divided into four groups. Each specimen was endodontically treated with step-back technique and prepared for each post system according to experimental groups, subsequently cemented in the canal. Composite resin cores were built and laboratory fabricated metal crowns were cemented. All specimens except those in the control group were subjected to thermal cycling. All groups were subjected to gradual loading from 0N-50N for 100 cycles. Specimens were sectioned transversely and the depths of dye penetration along the post were measured. Data were entered in SPSS ver. 22 and analyzed using two-way ANOVA test.

    Results: There was no significant difference in marginal dye penetration between each group (p-value>0.05). However, there was a significant difference in percentage of marginal dye penetration between all groups (p-value<0.05); post-hoc comparison showed significant difference between Fiber White and Control groups (p-value=0.009).

    Conclusion: All the groups showed dye penetration but the percentage was significant only between Parapost Fiber White and the control groups.

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