Displaying publications 21 - 36 of 36 in total

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  1. The effect of leg length inequality on joint contact forces of lower limbs during walking
    Fazreena Othman N, Salleh Basaruddin K, Hanafi Mat Som M, Shukry Abdul Majid M, Razak Sulaiman A
    Acta Bioeng Biomech, 2019;21(1):55-62.
    PMID: 31197285
    PURPOSE: The aim of this study was to examine the joint contact forces (JCF) between each limb as the LLD magnitude increases during walking activity.

    METHODS: Eighteen male healthy subjects volunteered to participate in the experiment. Walking gait analysis was conducted with eight different levels of insole to simulate the LLD, starting from 0 cm until 4.0 cm with 0.5 cm increment. Qualisys Track Manager System and C-motion Visual 3D biomechanical tools were used to analyse the results. Four joints (ankle, knee, hip, and pelvis) of lower limb of two legs were investigated. The increment of insoles was placed on the right leg to represent the long leg.

    RESULTS: The results suggest that the mean contact forces for all joints in the short leg were increased as the increment level increased. On the contrary, the mean contact forces in the long leg decreased when the LLD level increased. Among these four joints, JCF in hip shows a positive increment based on the ASI value. Means that hip shows the most affected joint as the LLD level increase.

    CONCLUSIONS: The result obtained in this study might help clinicians treat patients with a structural LLD for treatment plan including surgical intervention.

  2. Analysis and physicochemical properties of cellulose nanowhiskers from Pennisetum purpureum via different acid hydrolysis reaction time
    Sucinda EF, Abdul Majid MS, Ridzuan MJM, Sultan MTH, Gibson AG
    Int J Biol Macromol, 2020 Jul 15;155:241-248.
    PMID: 32240733 DOI: 10.1016/j.ijbiomac.2020.03.199
    Cellulose nanowhisker (NWC) was extracted by hydrolysing Pennisetum purpureum (PP) fibres with acid and alkali. They were subjected to different periods of acid hydrolysis; 30, 45, and 60 min. NWC morphology and physicochemical properties were characterised by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), particle size analyser, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis. NWC3, which underwent the longest hydrolysis time, showed the smallest width and length, under TEM. All samples presented a needle-like shape under TEM and AFM; uneven lengths and irregular shapes under FESEM; and a broad range of distribution, with the particle size analyser. All samples exhibited a good crystallinity index (CrI)-72.0 to 74.6%. The highest CrI% corresponded to 60 min of acid hydrolysis. Thermogravimetric analysis showed thermal stability between 310.72 °C and 336.28 °C. Thus, cellulose nanowhisker from PP fibres, have high potential as bio-nanocomposites.
  3. Enhanced production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) copolymer with manipulated variables and its properties
    Vigneswari S, Vijaya S, Majid MI, Sudesh K, Sipaut CS, Azizan MN, et al.
    J Ind Microbiol Biotechnol, 2009 Apr;36(4):547-56.
    PMID: 19189144 DOI: 10.1007/s10295-009-0525-z
    Cupriavidus sp. USMAA1020, a local isolate was able to biosynthesis poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)] copolymer with various 4HB precursors as the sole carbon source. Manipulation of the culture conditions such as cell concentration, phosphate ratio and culture aeration significantly affected the synthesis of P(3HB-co-4HB) copolymer and 4HB composition. P(3HB-co-4HB) copolymer with 4HB compositions ranging from 23 to 75 mol% 4HB with various mechanical and thermal properties were successfully produced by varying the medium aeration. The physical and mechanical properties of P(3HB-co-4HB) copolymers were characterized by NMR spectroscopy, gel-permeation chromatography, tensile test, and differential scanning calorimetry. The number-average molecular weights (M (n)) of copolymers ranged from 260 x 10(3) to 590 x 10(3)Da, and the polydispersities (M (w)/M (n)) were between 1.8 and 3.0. Increases in the 4HB composition lowered the molecular weight of these copolymers. In addition, the increase in 4HB composition affected the randomness of copolymer, melting temperature (T (m)), glass transition temperature (T (g)), tensile strength, and elongation to break. Enzymatic degradation of P(3HB-co-4HB) films with an extracellular depolymerase from Ochrobactrum sp. DP5 showed that the degradation rate increased proportionally with time as the 4HB fraction increased from 17 to 50 mol% but were much lower with higher 4HB fraction. Degradation of P(3HB-co-4HB) films with lipase from Chromobacterium viscosum exhibited highest degradation rate at 75 mol% 4HB. The biocompatibility of P(3HB-co-4HB) copolymers were evaluated and these copolymers have been shown to support the growth and proliferation of fibroblast cells.
  4. Particle swarm optimization and global sensitivity analysis for catalytic co-pyrolysis of Chlorella vulgaris and plastic waste mixtures
    Majid M, Chin BLF, Jawad ZA, Chai YH, Lam MK, Yusup S, et al.
    Bioresour Technol, 2021 Jun;329:124874.
    PMID: 33647605 DOI: 10.1016/j.biortech.2021.124874
    This study investigated on the co-pyrolysis of microalgae Chlorella vulgaris and high-density polyethylene (HDPE) waste mixtures which was performed with three types of catalysts, namely limestone (LS), HZSM-5 zeolite, and novel bi-functional LS/HZSM-5/LS. Kissinger-Kai (K-K) model-free method was coupled with Particle Swarm Optimization (PSO) model-fitting method using the thermogravimetric experimental data. A global sensitivity analysis was carried out using Latin Hypercube Sampling and rank transformation to assess the extent of impact of the input kinetic parameters on the output results. Furthermore, a thermodynamic analysis was performed to obtain parameters such as enthalpy change (ΔH), Gibb's free energy (ΔG), and entropy change (ΔS). The activation energy (EA) of the microalgae Chlorella vulgaris and HDPE binary mixture were found to be lower upon the addition of catalysts. Among the catalyst used, bi-functional LS/HZSM-5 catalyst exhibited the lowest EA (83.59 kJ/mol) and ΔH (78 kJ/mol) as compared to LS and HZSM-5 catalysts.
  5. Mechanical, thermal and morphological characterisation of 3D porous Pennisetum purpureum/PLA biocomposites scaffold
    Revati R, Abdul Majid MS, Ridzuan MJM, Normahira M, Mohd Nasir NF, Rahman Y MN, et al.
    Mater Sci Eng C Mater Biol Appl, 2017 Jun 01;75:752-759.
    PMID: 28415525 DOI: 10.1016/j.msec.2017.02.127
    The mechanical, thermal, and morphological properties of a 3D porous Pennisetum purpureum (PP)/polylactic acid (PLA) based scaffold were investigated. In this study, a scaffold containing P. purpureum and PLA was produced using the solvent casting and particulate leaching method. P. purpureum fibre, also locally known as Napier grass, is composed of 46% cellulose, 34% hemicellulose, and 20% lignin. PLA composites with various P. purpureum contents (10%, 20%, and 30%) were prepared and subsequently characterised. The morphologies, structures and thermal behaviours of the prepared composite scaffolds were characterised using field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The morphology was studied using FESEM; the scaffold possessed 70-200μm-sized pores with a high level of interconnectivity. The moisture content and mechanical properties of the developed porous scaffolds were further characterised. The P. purpureum/PLA scaffold had a greater porosity factor (99%) and compression modulus (5.25MPa) than those of the pure PLA scaffold (1.73MPa). From the results, it can be concluded that the properties of the highly porous P. purpureum/PLA scaffold developed in this study can be controlled and optimised. This can be used to facilitate the construction of implantable tissue-engineered cartilage.
  6. In vitro and in vivo evaluation of self-microemulsifying drug delivery system of buparvaquone
    Venkatesh G, Majid MI, Mansor SM, Nair NK, Croft SL, Navaratnam V
    Drug Dev Ind Pharm, 2010 Jun;36(6):735-45.
    PMID: 20136493 DOI: 10.3109/03639040903460446
    The aim of this study was to prepare a lipid-based self-microemulsifying drug delivery system (SMEDDS) to increase the solubility and oral bioavailability of a poorly water-soluble compound, buparvaquone (BPQ).
  7. Development and characterisation of packaging film from Napier cellulose nanowhisker reinforced polylactic acid (PLA) bionanocomposites
    Sucinda EF, Abdul Majid MS, Ridzuan MJM, Cheng EM, Alshahrani HA, Mamat N
    Int J Biol Macromol, 2021 Sep 30;187:43-53.
    PMID: 34271052 DOI: 10.1016/j.ijbiomac.2021.07.069
    A packaging material that is environment-friendly with excellent mechanical and physicochemical properties, biodegradable and ultraviolet (UV) protection and thermal stability was prepared to reduce plastic waste. Six different concentrations of Pennisetum purpureum/Napier cellulose nanowhiskers (NWCs) (i.e. 0, 0.5, 1.0, 1.5, 2.0, and 3.0 wt%) were used to reinforce polylactic acid (PLA) by a solvent casting method. The resulting bionanocomposite film samples were characterised in terms of their morphology, chemical structure, crystallinity, thermal degradation and stability, light transmittance, water absorption, biodegradability, and physical and mechanical properties. Field-emission scanning electron microscopy showed the excellent dispersion of NWC in the PLA matrix occurred with NWC concentrations of 0.5-1.5 wt%. All the bionanocomposite film samples exhibited good thermal stability at approximately 343-359 °C. The highest water absorption was 1.94%. The lowest transparency at λ800 was 16.16% for the PLA/3.0% NWC bionanocomposite film, which also has the lowest UVA and UVB transmittance of 7.49% and 4.02%, respectively, making it suitable for packaging materials. The PLA/1.0% NWC film exhibited the highest crystallinity of 50.09% and high tensile strength and tensile modulus of 21.22 MPa and 11.35 MPa, respectively.
  8. In vitro biodegradation, cytotoxicity, and biocompatibility of polylactic acid/napier cellulose nanofiber scaffold composites
    Revati R, Majid MSA, Ridzuan MJM, Mamat N, Cheng EM, Alshahrani HA
    Int J Biol Macromol, 2022 Dec 31;223(Pt A):479-489.
    PMID: 36368357 DOI: 10.1016/j.ijbiomac.2022.11.041
    This study aimed to evaluate the bioactivities and biocompatibilities of porous polylactic acid (PLA) reinforced with cellulose nanofiber (CNF) scaffolds. The in vitro degradation behaviors of the porous PLA/CNF scaffolds were systematically measured for up to 8 weeks in a phosphate-buffered saline medium at 37 °C. The reinforcement of CNF resisted the biodegradation of the scaffolds. The in vitro cytotoxicity and biocompatibility of the scaffolds were determined using the Beas2B American Type Culture Collection cells. The 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide cytotoxicity and proliferation tests showed that the scaffolds were non-toxic, and epithelial cells grew well on the scaffold after 7 days of culture, whereas the percentage of cell proliferation on the PLA/CNF15 scaffold was the largest, 130 %. A scratch wound-healing assay was performed to evaluate the suitability of the scaffolds for cell migration. The results demonstrated that the scaffolds exhibited good cell migration towards nearly complete wound closure.
  9. Occurrence of vancomycin-resistant enterococci in ducks in Malaysia
    Shah-Majid M, Azlina AM, Ana Maria AR, Zaharah B, Norhaliza AH
    Vet Rec, 2004 Nov 20;155(21):680-1.
    PMID: 15581146
  10. Seroprevalences and their associated predictors of chikungunya, dengue, Japanese encephalitis and zika among forest fringe dwellers of Peninsular Malaysia
    Khor CS, Lee HY, Abd-Majid MA, Khoo HY, Khoo JJ, AbuBakar S
    Trop Biomed, 2024 Jun 01;41(2):224-229.
    PMID: 39154278 DOI: 10.47665/tb.41.2.015
    Serological evidence has shown the presence of several mosquito-borne arbovirus infections among the inhabitants of the forest fringe areas of the tropics. Among these infections, Japanese encephalitis, dengue fever, chikungunya fever and Zika fever could be targeted for vaccination to overcome severe infection and limit the disease transmission. Seroprevalence data among this high-risk population are needed to provide an estimate of the potential cost-effectiveness of any vaccine programme targeting these infections. The present study was conducted at six indigenous people (Orang Asli) villages and FELDA (Federal Land Development Authority) settlements located at the forest fringes of Malaysia. All participants consented and provided blood samples and demographic data for the study. The blood samples were tested for the presence of antibodies against CHIKV, DENV, JEV and ZIKV individually using ELISA. Results obtained were also analysed to determine the predictors for CHIKV, DENV, JEV and ZIKV seropositivity. Among the 585 samples tested, 33.0% (N=193), 41.7% (N=244), 10.3% (N=60) and 21.0% (N=123) were positive for CHIKV IgG, DENV IgG, JEV IgG and ZIKV IgG, respectively. Approximately one-third (N=220, 37.6%) of the participants were tested negative for IgG antibodies against all four arboviruses. Age of participants and type of settlement were found to be a significant predictor for CHIKV, DENV, JEV and ZIKV seropositivity. Level of education was a significant predictor for CHIKV, DENV and ZIKV seropositivity. Gender, however, was not found to be a significant predictor for infection with any of these viruses. These findings reaffirmed the significant presence of infection involving these major arboviruses among the group of people living within the forest fringe areas of Peninsular Malaysia. Hence, any future consideration of vaccination for these infections must take into consideration the marginalized and underserved communities living at the forest fringe areas of the tropics where these infections are present.
  11. Review on the seroprevalence of neglected tropical diseases affecting the indigenous community in Malaysia (from 2010-2022)
    Lee HY, Khoo HY, Yap PC, Mansor SM, Abdul Majid MA
    Trop Biomed, 2024 Sep 01;41(3):276-282.
    PMID: 39548781 DOI: 10.47665/tb.41.3.007
    The indigenous community in Malaysia also known as Orang Asli have preserved their unique cultural identity in the face of rapid national development and modernization efforts. Over the years, poverty alleviation has become a central pillar of Malaysia development. In this review, seroprevalence report from the Orang Asli and their health status about neglected tropical diseases were collated and analyzed. The review will show the potential areas of research for future development. Specifically, the review will cover a 12-year period preceding the onset of COVID-19 pandemic, offering critical insights into the community health landscape. In depth discussion on the unique impact of the pandemic covering healthcare access, socioeconomic dynamics and community resilience. Analysis revealed the burden of parasitism is high in the community and the sustainability of certain basic access such as clean water and education remains a challenge. Different approaches to improve future intervention strategies were also discussed. The review can contribute to essential knowledge for policymakers, researchers, healthcare providers interested in enhancing the well-being of the Orang Asli community.
  12. Dielectric and material analysis on physicochemical activity of porous hydroxyapatite/cornstarch composites
    Beh CY, Cheng EM, Mohd Nasir NF, Eng SK, Abdul Majid MS, Ridzuan MJM, et al.
    Int J Biol Macromol, 2021 Jan 01;166:1543-1553.
    PMID: 33181217 DOI: 10.1016/j.ijbiomac.2020.11.034
    This paper provides a comprehensive analysis of the dielectric and physicochemical properties of the porous hydroxyapatite/cornstarch (HAp/Cs) composites in a new perspective. The porous composites have been characterized via SEM, FTIR, XRD and dielectric spectroscopy. The dielectric permittivity spectra were obtained in Ku-band (12.4-18.0 GHz) and it was correlated with the physicochemical properties of the porous HAp/Cs. Porous HAp/Cs composites exhibits low ε' and negative ε″, which influenced by the microstructural morphology, interaction between Hap and Cs, as well as crystalline features due to the various proportion of the HAp/Cs. The physicochemical effect of the composites results in the dielectric polarization and energy loss. This phenomenon indicates the presence of the three obvious relaxation responses in the ε' spectrum (13.2-14.0, 15.2-16.0, and 16.6-17.4 GHz) and the negative behaviours in the ε″ spectrum. The relationships between physicochemical and dielectric properties of the porous composite facilitate the development of the non-destructive microwave evaluation test for the porous composite.
  13. Low Frequency Dielectric and Optical Behavior on Physicochemical Properties of Hydroxyapatite/Cornstarch Composite
    Beh CY, Cheng EM, Mohd Nasir NF, Khor SF, Eng SK, Abdul Majid MS, et al.
    J Colloid Interface Sci, 2021 Oct 15;600:187-198.
    PMID: 34015511 DOI: 10.1016/j.jcis.2021.03.158
    An investigation on relationship among the physicochemical, optical and dielectric properties of the hydroxyapatite/cornstarch (HA/Cs) composites with the starch proportion of 30, 40, 50, 60, 70, 80 and 90 wt% is presented in this work. The HA/Cs composites have been characterized via FTIR, XRD, DRS and impedance analyzer. This work depicts that the strong interaction is exhibited between the hydroxyapatite nanoparticles and starch as the starch proportion increases. This increment trend results in the higher crystallinity of the HA/Cs composites. The highly crystallized HA/Cs with hydroxyapatite nucleation center presents low optical properties (diffuse reflectance and optical band gap energy). The HA/Cs composite with 80 wt% starch proportion (H2C8) show higher dielectric properties (dielectric constant, loss factor and conductivity) due to the stronger interfacial interaction and close-packed HA/Cs crystalline structure. The relationship among the physicochemical, optical and dielectric properties of the HA/Cs composite is studied in this work for potential of instrumentation design.
  14. In vitro degradation of a 3D porous Pennisetum purpureum/PLA biocomposite scaffold
    Revati R, Majid MSA, Ridzuan MJM, Basaruddin KS, Rahman Y MN, Cheng EM, et al.
    J Mech Behav Biomed Mater, 2017 10;74:383-391.
    PMID: 28688321 DOI: 10.1016/j.jmbbm.2017.06.035
    The in vitro degradation and mechanical properties of a 3D porous Pennisetum purpureum (PP)/polylactic acid (PLA)-based scaffold were investigated. In this study, composite scaffolds with PP to PLA ratios of 0%, 10%, 20%, and 30% were immersed in a PBS solution at 37°C for 40 days. Compression tests were conducted to evaluate the compressive strength and modulus of the scaffolds, according to ASTM F451-95. The compression strength of the scaffolds was found to increase from 1.94 to 9.32MPa, while the compressive modulus increased from 1.73 to 5.25MPa as the fillers' content increased from 0wt% to 30wt%. Moreover, field emission scanning electron microscopy (FESEM) and X-ray diffraction were employed to observe and analyse the microstructure and fibre-matrix interface. Interestingly, the degradation rate was reduced for the PLA/PP20scaffold, though insignificantly, this could be attributed to the improved mechanical properties and stronger fibre-matrix interface. Microstructure changes after degradation were observed using FESEM. The FESEM results indicated that a strong fibre-matrix interface was formed in the PLA/PP20scaffold, which reflected the addition of P. purpureum into PLA decreasing the degradation rate compared to in pure PLA scaffolds. The results suggest that the P. purpureum/PLA scaffold degradation rate can be altered and controlled to meet requirements imposed by a given tissue engineering application.
  15. Bacterial profiling of head lice isolated from the Orang Asli: A first report in Malaysia
    Abd Majid MA, Khoo JJ, Lim FS, Khor CS, Loong SK, Low VL, et al.
    Trop Biomed, 2020 Dec 01;37(4):884-895.
    PMID: 33612742 DOI: 10.47665/tb.37.4.884
    This study was carried out to determine from bacterial profiling to the bacterial profiles of head lice among the Orang Asli communities. The head lice were collected from Orang Asli community volunteers. The surface sterilized head lice pools were subjected to genomic DNA extraction while next generation sequencing of the 16S rRNA gene was performed using the Illumina MiSeq platform. Six female and three male head lice identified as Pediculus humanus capitis were collected. A total of 111 368 number of NGS sequencing reads were recorded while another 223 bacterial taxa sequences were obtained. Symbiotic bacteria showed the highest number of reads, with Arsenophonus and Rhodococcus sequences being the most abundant genera in the female and male samples, respectively. The female head lice contained a more distinct microbial diversity. Amongst the pathogenic bacterial species sequences noted were the methicillin-resistant Staphylococcus aureus, Streptobacillus moniliformis, Haemophilus influenzae, Bordetella pertussis and Acinetobacter baumannii. The 16S rRNA genome sequencing revealed a number of rare and pathogenic bacterial species within the head lice of the Orang Asli. The socio-economic practices of the community which involved forest foraging and hunting, and their poor living conditions potentially facilitated the transmission of zoonotic bacterial pathogens, including those found within the head lice. Hence, there is the possibility that the head lice could serve as vectors for the transmission of pathogenic bacteria. This study highlighted the diverse microbial community found within the head lice's gut of the Orang Asli, with the detection of multiple rare and pathogenic bacteria capable of causing severe infections.
  16. Fulltext Role of neurotoxicants in the pathogenesis of Alzheimer's disease: a mechanistic insight
    Nisa FY, Rahman MA, Hossen MA, Khan MF, Khan MAN, Majid M, et al.
    Ann Med, 2021 Dec;53(1):1476-1501.
    PMID: 34433343 DOI: 10.1080/07853890.2021.1966088
    Alzheimer's disease (AD) is the most conspicuous chronic neurodegenerative syndrome, which has become a significant challenge for the global healthcare system. Multiple studies have corroborated a clear association of neurotoxicants with AD pathogenicity, such as Amyloid beta (Aβ) proteins and neurofibrillary tangles (NFTs), signalling pathway modifications, cellular stress, cognitive dysfunctions, neuronal apoptosis, neuroinflammation, epigenetic modification, and so on. This review, therefore, aimed to address several essential mechanisms and signalling cascades, including Wnt (wingless and int.) signalling pathway, autophagy, mammalian target of rapamycin (mTOR), protein kinase C (PKC) signalling cascades, cellular redox status, energy metabolism, glutamatergic neurotransmissions, immune cell stimulations (e.g. microglia, astrocytes) as well as an amyloid precursor protein (APP), presenilin-1 (PSEN1), presenilin-2 (PSEN2) and other AD-related gene expressions that have been pretentious and modulated by the various neurotoxicants. This review concluded that neurotoxicants play a momentous role in developing AD through modulating various signalling cascades. Nevertheless, comprehension of this risk agent-induced neurotoxicity is far too little. More in-depth epidemiological and systematic investigations are needed to understand the potential mechanisms better to address these neurotoxicants and improve approaches to their risk exposure that aid in AD pathogenesis.Key messagesInevitable cascade mechanisms of how Alzheimer's Disease-related (AD-related) gene expressions are modulated by neurotoxicants have been discussed.Involvement of the neurotoxicants-induced pathways caused an extended risk of AD is explicited.Integration of cell culture, animals and population-based analysis on the clinical severity of AD is addressed.
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