Browse publications by year: 2023

  1. Advancements in dextran-based nanocarriers for treatment and imaging of breast cancer
    Khan MS, Gowda BHJ, Nasir N, Wahab S, Pichika MR, Sahebkar A, et al.
    Int J Pharm, 2023 Aug 25;643:123276.
    PMID: 37516217 DOI: 10.1016/j.ijpharm.2023.123276
    Breast cancer is the most prevalent type of cancer worldwide,particularly among women, with substantial side effects after therapy. Despite the availability of numerous therapeutic approaches, particularly chemotherapy, the survival rates for breast cancer have declined over time. The therapies currently utilized for breast cancer treatment do not specifically target cancerous cells, resulting in significant adverse effects and potential harm to healthy cells alongside the cancer cells. As a result, nanoparticle-based drug delivery systems have emerged. Among various types of nanoparticles, natural polysaccharide-based nanoparticles have gained significant attention due to their ability to precisely control the drug release and achieve targeted drug delivery. Moreover, polysaccharides are biocompatible, biodegradable, easily modifiable, and renewable, which makes them a unique material for nanoformulation. In recent years, dextran and its derivatives have gained much interest in the field of breast cancer therapy. Dextran is a hydrophilic polysaccharide composed of a main chain formed by α-1,6 linked glucopyranoside residues and a side chain composed of residues linked in α-1,2/3/4 positions. Different dextran-antitumor medication conjugates enhancethe efficacy of anticancer agents. With this context, the present review provides brief insights into dextran and its modification. Further, it meticulously discusses the role of dextran-based nanoparticles in breast cancer therapy and imaging, followed by snippets on their toxicity. Lastly, it presents clinical trials and future perspectives of dextran-based nanoparticles in breast cancer treatment.
    MeSH terms: Antineoplastic Agents*; Dextrans/chemistry; Drug Carriers/chemistry; Female; Humans; Drug Delivery Systems
  2. Pharmaceutical residues in the ecosystem: Antibiotic resistance, health impacts, and removal techniques
    Husain Khan A, Abdul Aziz H, Palaniandy P, Naushad M, Cevik E, Zahmatkesh S
    Chemosphere, 2023 Oct;339:139647.
    PMID: 37516325 DOI: 10.1016/j.chemosphere.2023.139647
    Hospital wastewater has emerged as a major category of environmental pollutants over the past two decades, but its prevalence in freshwater is less well documented than other types of contaminants. Due to compound complexity and improper operations, conventional treatment is unable to remove pharmaceuticals from hospital wastewater. Advanced treatment technologies may eliminate pharmaceuticals, but there are still concerns about cost and energy use. There should be a legal and regulatory framework in place to control the flow of hospital wastewater. Here, we review the latest scientific knowledge regarding effective pharmaceutical cleanup strategies and treatment procedures to achieve that goal. Successful treatment techniques are also highlighted, such as pre-treatment or on-site facilities that control hospital wastewater where it is used in hospitals. Due to the prioritization, the regulatory agencies will be able to assess and monitor the concentration of pharmaceutical residues in groundwater, surface water, and drinking water. Based on the data obtained, the conventional WWTPs remove 10-60% of pharmaceutical residues. However, most PhACs are eliminated during the secondary or advanced therapy stages, and an overall elimination rate higher than 90% can be achieved. This review also highlights and compares the suitability of currently used treatment technologies and identifies the merits and demerits of each technology to upgrade the system to tackle future challenges. For this reason, pharmaceutical compound rankings in regulatory agencies should be the subject of prospective studies.
    MeSH terms: Drug Resistance, Microbial; Pharmaceutical Preparations; Environmental Monitoring; Prospective Studies; Ecosystem; Waste Water*
  3. Site suitability analysis for sanitary landfills using geospatial methods in a part of southern Peninsular Malaysia
    Arshad S, Lihan T, Rahman ZA, Idris WMR
    Environ Sci Pollut Res Int, 2023 Sep;30(41):93760-93778.
    PMID: 37516702 DOI: 10.1007/s11356-023-28764-7
    Globally, around 1.3 billion tonnes of waste are generated annually, and solid waste management has thus become a major concern worldwide. There are projections of a 70% increase in waste generation from 2016 to 2050 owing to urbanization and the rapid growth of the global population. Estimates indicate that around 38,200 tonnes of waste are generated per day in Malaysia, and this volume of waste is significantly shortening the planned life spans of operating sanitary landfills in the country. Batu Pahat is a district in the state of Johor, Malaysia, with a relatively large population of 495,000 and with no record of an operational sanitary landfill. This study was conducted to identify and classify the most suitable sites for sanitary landfill developments in southern Peninsular Malaysia by means of the Analytical Hierarchy Process (AHP), which is recognized as a competent technique for multicriteria decision-making. The resulting landfill site suitability index map established 33.88 km2 of area coverage as very highly suitable for landfill development, while 353.86 km2 of area coverage was classified as unsuitable. Sites 1-6 were identified as the most suitable for landfill activities. Sites 1-5 are situated in agricultural land areas, while site 6 is in a forested land area; this implies public participation and the adoption of compensatory measures in the event of landfill development in these areas, given their socioeconomic importance. The six suitable sites are all at least 2000 m from rivers: 2000-3000 m for sites 1, 3, and 5 and > 3000 m for sites 2, 4, and 6. The six sites are all > 3000 m from fault zones and > 1000 m from flood-prone areas, meaning that occurrences such as fault movements and flooding will have minimal impact on the operational activities of landfills at these sites. The selection of sites 1-6 as very suitable for landfill development was associated with an overall accuracy rating of 93.33% and kappa coefficient score of 0.92 based on accuracy assessment analysis of all sites. This study will guide the actions of policymakers, city planners, and local authorities toward sustainable and environment-friendly landfill development and operation in Batu Pahat and other districts in the state of Johor.
    MeSH terms: Decision Support Techniques; Malaysia; Geographic Information Systems; Solid Waste; Waste Disposal Facilities
  4. Fulltext A Hidden Condition: Multiple Tarlov Cysts Unveiled in a Young Woman Seeking Primary Care for Debilitating Low Back Pain
    Abu Hussain SM, Shibraumalisi NA, Miptah HN, Mohamad Ali ND, Yahaya MY, Ramli AS
    Am J Case Rep, 2023 Jul 30;24:e940600.
    PMID: 37516905 DOI: 10.12659/AJCR.940600
    BACKGROUND Tarlov cysts are rare, with a prevalence of 3.3% in the Asian population, and symptomatic cases are even rarer. Here, we report a case of a young woman with multiple Tarlov cysts presenting in primary care with severe low back pain. CASE REPORT A 23-year-old Malay woman presented to a primary care clinic with sudden-onset, severe, and persistent low back pain for 1 week, affecting her activities of daily living (ADL), especially as a medical student, as she could not stand for more than 10 minutes. There were no other associated symptoms or recent trauma prior to the onset of back pain. Examinations revealed para-vertebrae muscle tenderness and restricted movements at the L4/L5 lumbosacral spine. A plain radiograph of the lumbosacral spine showed sclerosis and erosion of the right pedicle at the L4/L5 levels. Tuberculosis and haematological tests were normal. A lumbosacral MRI of the spine was ordered and the patient was urgently referred to the orthopaedic spine team. The MRI confirmed the diagnosis of multiple Tarlov cysts, with the dominant cyst located at the S2 level. Her symptoms and ADL improved with conservative management. She is being monitored closely by the orthopaedic team and primary care physician. CONCLUSIONS This case highlights red flag symptoms, ie, sudden-onset, severe, and persistent low back pain, that warrant further investigation. Tarlov cysts should be considered as a differential diagnosis. Close monitoring is vital and early surgical intervention is indicated if symptoms worsen, to prevent potential irreversible nerve damage.
    MeSH terms: Activities of Daily Living; Adult; Cysts*; Female; Humans; Primary Health Care; Young Adult
  5. Optic nerve sheath diameter in COVID-19: there's more to it than meets the eye
    Magoon R, Suresh V
    QJM, 2023 Jul 28;116(7):599-600.
    PMID: 36617160 DOI: 10.1093/qjmed/hcad002
    MeSH terms: Central Nervous System; Humans; Ultrasonography
  6. Secukinumab for Netherton syndrome: a Malaysian experience
    Ting IPL, Lee TS, Teo HG, Albela H, Tang MM, Leong KF
    Clin Exp Dermatol, 2023 Nov 16;48(12):1366-1369.
    PMID: 37503742 DOI: 10.1093/ced/llad253
    MeSH terms: Humans; Ichthyosiform Erythroderma, Congenital*; Antibodies, Monoclonal, Humanized/therapeutic use
  7. Fulltext Formation of Hydroxyapatite-Based Hybrid Materials in the Presence of Platelet-Poor Plasma Additive
    Glazov IE, Krut'ko VK, Safronova TV, Sazhnev NA, Kil'deeva NR, Vlasov RA, et al.
    Biomimetics (Basel), 2023 Jul 09;8(3).
    PMID: 37504185 DOI: 10.3390/biomimetics8030297
    Biomaterials based on hydroxyapatite with controllable composition and properties are promising in the field of regenerative bone replacement. One approach to regulate the phase composition of the materials is the introduction of biopolymer-based additives into the synthesis process. The purpose of present study was to investigate the formation of hydroxyapatite-based hybrid materials in the presence of 6-24% platelet-poor plasma (PPP) additive, at a [Ca2+]/[PO43-] ratio of 1.67, pH 11, and varying maturing time from 4 to 9 days. The mineral component of the materials comprised 53% hydroxyapatite/47% amorphous calcium phosphate after 4 days of maturation and 100% hydroxyapatite after 9 days of maturation. Varying the PPP content between 6% and 24% brought about the formation of materials with rather defined contents of amorphous calcium phosphate and biopolymer component and the desired morphology, ranging from typical apatitic conglomerates to hybrid apatite-biopolymer fibers. The co-precipitated hybrid materials based on hydroxyapatite, amorphous calcium phosphate, and PPP additive exhibited increased solubility in SBF solution, which defines their applicability for repairing rhinoplastic defects.
  8. Fulltext Multilocus Sequence Analysis and Detection of Copper Ion Resistance of Xanthomonas phaseoli pv. manihotis Causing Bacterial Blight in Cassava
    Shi T, Li C, Wang G, Huang G
    Curr Issues Mol Biol, 2023 Jun 28;45(7):5389-5402.
    PMID: 37504258 DOI: 10.3390/cimb45070342
    Cassava (Manihot esculenta Crantz) is an important tropical tuber crop around the world. Cassava bacterial blight, caused by Xanthomonas phaseoli pv. manihotis, is a key disease that influences cassava production worldwide. Between 2008 and 2020, 50 X. phaseoli pv. manihotis strains were isolated from diseased plant samples or acquired from China, Uganda, Cambodia, Colombia, Malaysia, and Micronesia. Using multilocus sequence analysis, the genetic diversity of X. phaseoli pv. manihotis strains was evaluated. A neighbor-joining phylogenetic dendrogram was constructed based on partial sequences of five housekeeping genes (atpD-dnaK-gyrB-efp-rpoD). The strains clustered into three groups whose clusters were consistent with atpD and RpoD gene sequences. Group I contained 46 strains from China, Uganda, Cambodia, and Micronesia, and the other two groups were comprised of strains from Colombia and Malaysia, respectively. The resistance of all these strains to copper ion (Cu2+) was determined, the minimal inhibitory concentration was between 1.3 and 1.7 mM, and there was no significant difference between strains from different geographic region. During genome annotation of the X. phaseoli pv. manihotis strain CHN01, homologous gene clusters of copLAB and xmeRSA were identified. The predicted amino acid sequences of two gene clusters were highly homologous with the copper-resistant protein from Xanthomonas strains. CopLAB and xmeRSA were amplified from all these strains, suggesting that the regulation of copper resistance is associated with two distinct metabolic pathways. CopLAB and xmeRSA were highly conserved among strains from different geographic regions, possibly associated with other conserved function.
  9. Fulltext 4D Printing in Biomedical Engineering: Advancements, Challenges, and Future Directions
    Ramezani M, Mohd Ripin Z
    J Funct Biomater, 2023 Jun 29;14(7).
    PMID: 37504842 DOI: 10.3390/jfb14070347
    4D printing has emerged as a transformative technology in the field of biomedical engineering, offering the potential for dynamic, stimuli-responsive structures with applications in tissue engineering, drug delivery, medical devices, and diagnostics. This review paper provides a comprehensive analysis of the advancements, challenges, and future directions of 4D printing in biomedical engineering. We discuss the development of smart materials, including stimuli-responsive polymers, shape-memory materials, and bio-inks, as well as the various fabrication techniques employed, such as direct-write assembly, stereolithography, and multi-material jetting. Despite the promising advances, several challenges persist, including material limitations related to biocompatibility, mechanical properties, and degradation rates; fabrication complexities arising from the integration of multiple materials, resolution and accuracy, and scalability; and regulatory and ethical considerations surrounding safety and efficacy. As we explore the future directions for 4D printing, we emphasise the need for material innovations, fabrication advancements, and emerging applications such as personalised medicine, nanomedicine, and bioelectronic devices. Interdisciplinary research and collaboration between material science, biology, engineering, regulatory agencies, and industry are essential for overcoming challenges and realising the full potential of 4D printing in the biomedical engineering landscape.
  10. Fulltext Physicochemical Characterization of Thermally Processed Goose Bone Ash for Bone Regeneration
    Abdul Rahman FS, Abdullah AM, Radhi A, Shahidan WNS, Abdullah JY
    J Funct Biomater, 2023 Jun 30;14(7).
    PMID: 37504846 DOI: 10.3390/jfb14070351
    Goose bone is traditionally applied for many ailments including bone fractures. Goose bone that consists of calcium phosphate plays a major role in bone regeneration. In this study, the production of goose bone ash (GBA) was translated from a traditional process into one of a laboratory scale via thermal and mechanical methods. The GBA was thermally processed via calcination at 300 °C and 900 °C. The differences in physicochemical properties between studied GBA (SGBA) and commercial GBA (CGBA) were elucidated via Fourier transform infrared (FT-IR), X-ray fluorescence (XRF), X-ray diffraction (XRD) and electron diffraction X-Ray (EDX). The morphological properties of SGBA and CGBA were characterized using field emission scanning electron microscopy (FESEM) in which nano-sized particles were detected. The results showed that the SGBA of 300 °C had comparable physicochemical properties to those of CGBA. A high processing temperature was associated with decreasing organic compounds and increasing crystallinity. The finding from EDX suggests that sintering at 900 °C (SGBA 900) demonstrated the presence of hydroxyapatite in the mineralogical phase and had a Ca/P atomic ratio of 1.64 which is comparable to the ideal stoichiometric ratio of 1.67. Findings from this study could be used for the further exploration of GBA as a potential material for bone regeneration via the elucidation of their biological properties in the next experimental setting.
  11. Fulltext Strategies to Enhance the Membrane-Based Processing Performance for Fruit Juice Production: A Review
    Katibi KK, Mohd Nor MZ, Yunos KFM, Jaafar J, Show PL
    Membranes (Basel), 2023 Jul 20;13(7).
    PMID: 37505045 DOI: 10.3390/membranes13070679
    Fruit juice is an essential food product that has received significant acceptance among consumers. Harmonized concentration, preservation of nutritional constituents, and heat-responsive sensorial of fruit juices are demanding topics in food processing. Membrane separation is a promising technology to concentrate juice at minimal pressure and temperatures with excellent potential application in food industries from an economical, stable, and standard operation view. Microfiltration (MF) and ultrafiltration (UF) have also interested fruit industries owing to the increasing demand for reduced pressure-driven membranes. UF and MF membranes are widely applied in concentrating, clarifying, and purifying various edible products. However, the rising challenge in membrane technology is the fouling propensity which undermines the membrane's performance and lifespan. This review succinctly provides a clear and innovative view of the various controlling factors that could undermine the membrane performance during fruit juice clarification and concentration regarding its selectivity and permeance. In this article, various strategies for mitigating fouling anomalies during fruit juice processing using membranes, along with research opportunities, have been discussed. This concise review is anticipated to inspire a new research platform for developing an integrated approach for the next-generation membrane processes for efficient fruit juice clarification.
  12. Correction: Vitamin D status and clinical implications in the adult population of Malaysia: a position paper by the Malaysian Vitamin D Special Interest Group
    Lee JK, Chee WSS, Foo SH, Lee VKM, Sallehuddin H, Khor HM, et al.
    Osteoporos Int, 2023 Nov;34(11):1851-1852.
    PMID: 37505306 DOI: 10.1007/s00198-023-06865-w
  13. Fulltext A Comprehensive Review of Cervical Cancer Screening Devices: The Pros and the Cons
    Hon HJ, Chong PP, Choo HL, Khine PP
    Asian Pac J Cancer Prev, 2023 Jul 01;24(7):2207-2215.
    PMID: 37505749 DOI: 10.31557/APJCP.2023.24.7.2207
    OBJECTIVE: The low screening coverage and reluctance of women in participation lead to low uptake in cervical screening tests. Hence the majority of cervical cancer patients visiting the hospitals are diagnosed at advanced stage, often leading to poor survival rate. This paper aims to review and compile available cancer screening devices so that more people in this field will adopt suitable devices in cervical cancer screening routine depending on requirements which may encourage the uptake in cervical screening tests.

    METHODS: This paper reviews devices invented for different cervical cancer screening methods, which are Pap smear test, visual inspection with acetic acid (VIA) or Lugol's iodine (VILI), and HPV (human papillomavirus)-DNA (deoxyribonucleic acid) self-test in terms of functionality, performance in solving the limitations of screening procedure and additionally where applicable, the cervical cell collection efficacy and abnormality detection accuracy. The devices are either available in the market, published in research articles or published in international patent databases.

    RESULT: The reviewed devices either simplified the screening procedure to improve the clinical efficiency and accuracy in screening, reduced the pain and discomfort experienced by women during screening procedures, or achieved both outcomes.

    CONCLUSION: Many devices have been invented to improve the screening procedures which may potentially improve the uptake in cervical screening tests and encourage the organization of screening campaigns to reduce cervical cancer incidence.

    MeSH terms: Uterine Cervical Dysplasia*; Uterine Cervical Neoplasms*; Cervix Uteri; Female; Humans; Iodides; Mass Screening/methods; Vaginal Smears/methods; Acetic Acid; Papillomavirus Infections*; Early Detection of Cancer/methods
  14. Fulltext Induction of Apoptosis and Modulation of Caspase Activity on MCF-7 Human Breast Cancer Cells by Bioactive Fractionated Cocoa Leaf Extract
    Ranneh Y, Abu Bakar MF, Md Akim A, Bin Baharum Z, S Ellulu M, Fadel A
    Asian Pac J Cancer Prev, 2023 Jul 01;24(7):2473-2483.
    PMID: 37505782 DOI: 10.31557/APJCP.2023.24.7.2473
    BACKGROUND: The objective of this study was to investigate the potential anti-proliferative activities of a methanolic extract of cocoa leaves (CL) obtained through sequential partition and fractionation against MCF-7 breast cancer cells.  Methods: The methanolic extract of CL was partitioned in three separated solvents (hexane, dichloromethane, and methanol). Hexane partition was the most potent against MCF-7 cells growth with the lowest IC50 value. Then, it was subjected to two fractionation procedures, resulting in the identification of the CL bioactive fraction (II-F7) with potent toxicity against MCF-7 cells.

    RESULTS: Further investigation into CL bioactive fraction (II-F7) revealed significant dose-dependent growth inhibitory effects on MCF-7 cells, which were attributed to the induction of apoptosis, as evidenced by the presence of apoptotic bodies, fragmented DNA, and disruption of mitochondrial membrane potential. Additionally, treatment with CL bioactive fraction (II-F7) upregulated the expression of pro-apoptotic genes (DDIT3, GADD45G and HRK) and significantly increased the activities of caspase-8 and caspase-9.

    CONCLUSION: Overall, this study suggests that bioactive fraction (II-F7) from CL extract has significant and selective cytotoxicity against MCF-7 cells through inducing apoptosis and has potential as a therapeutic agent for breast cancer treatment.

    MeSH terms: Female; Hexanes/pharmacology; Hexanes/therapeutic use; Humans; Plant Extracts/pharmacology; Plant Extracts/therapeutic use; Apoptosis; Caspases; Cell Line, Tumor; Cell Proliferation; Caspase 3/metabolism; MCF-7 Cells
  15. Fulltext Internet addiction and its relationship with attention deficit hyperactivity disorder (ADHD) symptoms, anxiety and stress among university students in Malaysia
    Zakaria H, Hussain I, Zulkifli NS, Ibrahim N, Noriza NJ, Wong M, et al.
    PLoS One, 2023;18(7):e0283862.
    PMID: 37506072 DOI: 10.1371/journal.pone.0283862
    BACKGROUND AND AIMS: There is growing evidence on the contribution of psychological factors to internet addiction; yet it remains inconsistent and deserves further exploration. The aim of this study was to determine the relationship between the psychological symptoms (Attention Deficit Hyperactivity Disorder (ADHD) symptoms, stress, depression, anxiety and loneliness) and internet addiction (IA) among the university students in Malaysia.

    MATERIALS AND METHODS: A total of 480 students from different faculties in a Malaysian public university participated in this study. They were selected by simple random sampling method. They completed self-administered questionnaires including the Malay Version of Internet Addiction Test (MVIAT)) to measure internet addiction and Adult Self-Report Scale (ASRS) Symptom Checklist, Depression Anxiety Stress Scales (DASS) and UCLA Loneliness Scale (Version 3) to assess for ADHD symptoms, depression, anxiety, stress, and loneliness respectively.

    RESULTS: The prevalence of IA among university students was 33.33% (n = 160). The respondents' mean age was 21.01 ± 1.29 years old and they were predominantly females (73.1%) and Malays (59.4%). Binary logistic regression showed that gender (p = 0.002; OR = 0.463, CI = 0.284-0.754), ADHD inattention (p = 0.003; OR = 2.063, CI = 1.273-3.345), ADHD hyperactivity (p<0.0001; OR = 2.427, CI = 1.495-3.939), stress (p = 0.048; OR = 1.795, CI = 1.004-3.210) and loneliness (p = 0.022; OR = 1.741, CI = 1.084-2.794) were significantly associated with IA.

    CONCLUSION: A third of university students had IA. In addition, we found that those who were at risk of IA were males, with ADHD symptoms of inattention and hyperactivity, who reported stress and loneliness. Preventive strategy to curb internet addiction and its negative sequelae may consider these factors in its development and implementation.

    MeSH terms: Adult; Anxiety/diagnosis; Female; Humans; Malaysia/epidemiology; Male; Students/psychology; Universities; Internet; Young Adult
  16. Photobiomodulation Therapy in Carpal Tunnel Release: A Randomized Controlled Trial
    Chuah JP, Khoo SS, Chung TY, Jayaletchumi G
    Photobiomodul Photomed Laser Surg, 2023 Aug;41(8):402-407.
    PMID: 37506348 DOI: 10.1089/photob.2023.0018
    Background: Carpal tunnel release (CTR) is widely accepted as an effective treatment for carpal tunnel syndrome. However, the recovery is often delayed and incomplete. Photobiomodulation therapy (PBMT) produces a nonthermal effect on living tissues; it promotes healing, remodels and reduces inflammation of an injured nerve. The purpose of this study was to compare the outcome of CTR between patients who underwent postoperative PBMT and without PBMT. Materials and methods: We recruited 105 patients who had open CTR from January 2019 to January 2021. Fifty-six patients fulfilled the study criteria and were randomized into two groups: with PBMT (n = 28) and without PBMT (n = 28). Demographic and clinical data were obtained preoperatively. The PBMT group had ten 3-min sessions over 3 weeks using 808 nm, 50 mW PBMT to deliver 9 J per session to the CTR incision scar. Clinical outcomes were assessed at 1, 3, and 6 months postoperatively. Data analysis was performed with SPSS software. Results: There were significant improvements in the Functional Status Scale in the Boston Carpal Tunnel Questionnaire (p = 0.018) and pain (visual analogue scales) in the morning (p = 0.019) at 1 month postoperatively in the PBMT group compared with the non-PBMT group. Improvement of tip pinch strength at 3 months (p = 0.022) and 6 months (p = 0.024), lateral pinch strength at 1 month (p = 0.042) and 3 months (p = 0.05), and tripod pinch strength at 3 months (p = 0.005) was significantly better in the PBMT group. Thumb 2-point discrimination (2PD) at 3 months (p = 0.018) and 6 months (p = 0.016) and index finger 2PD at 3 months (p = 0.039) were also significantly improved in the PBMT group. There were no side effects of PBMT reported. Conclusions: Patients who underwent PBMT post-CTR had better outcomes. PBMT may be a valuable adjunct to post-CTR care.
    MeSH terms: Humans; Pain; Wrist; Treatment Outcome; Low-Level Light Therapy*
  17. Switched step integral backstepping control for nonlinear motion systems with application to a laboratory helicopter
    Haruna A, Mohamed Z, Efe MÖ, Abdullahi AM
    ISA Trans, 2023 Oct;141:470-481.
    PMID: 37507325 DOI: 10.1016/j.isatra.2023.07.002
    In this paper, the energy efficiency of the widespread application of backstepping control to a class of nonlinear motion systems is investigated. A Switched Step Integral Backstepping Control (SSIBC) scheme is introduced to improve immunity to measurement noise and to increase the energy efficiency of conventional backstepping in practice. The SSIBC is realized by switching between two candidate controllers obtained at different steps of the iterative backstepping design process. A bi-state dependent hysteresis rule is developed to supervise stable switching between the different regimes in the presence of noise. The proposed method is experimentally verified on a MIMO twin rotor laboratory helicopter involving coupled nonlinear dynamics, inaccessible states and uncertainties. Experimental results show that in addition to a reduction in power consumption, the SSIBC reduces saturation of the control signal and visible motor jerking in contrast with conventional backstepping. Additional comparisons with a previously proposed optimized decoupling PID controller also show significant improvement in precision achieved with higher energy efficiency. Experimental results obtained with the introduction of an external disturbance into the system also show the robustness of the proposed SSIBC.
  18. Fulltext Unveiling the functional epitopes of cobra venom cytotoxin by immunoinformatics and epitope-omic analyses
    Hiu JJ, Fung JKY, Tan HS, Yap MKK
    Sci Rep, 2023 Jul 28;13(1):12271.
    PMID: 37507457 DOI: 10.1038/s41598-023-39222-2
    Approximate 70% of cobra venom is composed of cytotoxin (CTX), which is responsible for the dermonecrotic symptoms of cobra envenomation. However, CTX is generally low in immunogenicity, and the antivenom is ineffective in attenuating its in vivo toxicity. Furthermore, little is known about its epitope properties for empirical antivenom therapy. This study aimed to determine the epitope sequences of CTX using the immunoinformatic analyses and epitope-omics profiling. A conserved CTX was used in this study to determine its T-cell and B-cell epitope sequences using immunoinformatic tools and molecular docking simulation with different Human Leukocyte Antigens (HLAs). The potential T-cell and B-cell epitopes were 'KLVPLFY,' 'CPAGKNLCY,' 'MFMVSTPTK,' and 'DVCPKNSLL.' Molecular docking simulations disclosed that the HLA-B62 supertype exhibited the greatest binding affinity towards cobra venom cytotoxin. The namely L7, G18, K19, N20, M25, K33, V43, C44, K46, N47, and S48 of CTX exhibited prominent intermolecular interactions with HLA-B62. The multi-enzymatic-limited-digestion/liquid chromatography-mass spectrometry (MELD/LC-MS) also revealed three potential epitope sequences as 'LVPLFYK,' 'MFMVS,' and 'TVPVKR'. From different epitope mapping approaches, we concluded four potential epitope sites of CTX as 'KLVPLFYK', 'AGKNL', 'MFMVSTPKVPV' and 'DVCPKNSLL'. Site-directed mutagenesis of these epitopes confirmed their locations at the functional loops of CTX. These epitope sequences are crucial to CTX's structural folding and cytotoxicity. The results concluded the epitopes that resided within the functional loops constituted potential targets to fabricate synthetic epitopes for CTX-targeted antivenom production.
    MeSH terms: Antivenins*; Elapid Venoms*; HLA Antigens; Humans; Epitopes, T-Lymphocyte; Epitopes, B-Lymphocyte; Molecular Docking Simulation
  19. An environmental assessment of the impacts of corruption, foreign investment inflow and trade liberalization in the rapidly emerging Malaysian Economy
    Gyamfi BA, Onifade ST, Ridzuan AR, Shaari MS, Jena PK
    Environ Sci Pollut Res Int, 2023 Sep;30(41):93667-93685.
    PMID: 37507569 DOI: 10.1007/s11356-023-28868-0
    In the wake of various catastrophic consequences of climate change, Malaysia, a rapidly developing economy, is also inevitably experiencing environmental degradation that merits prompt and serious attention from policymakers and its government. Hence, this study simultaneously highlights the short and long-run dynamic connections between carbon emission in Malaysia and the trio of corruption levels, foreign investment inflow, and trade liberalization. The study also controls for a combination of other factors including energy use, GDP, and urbanization. A robust empirical analysis was conducted on time series observations for the country based on the recent Dynamic ARDL simulation. It was observed that Malaysia's per capita pollution levels significantly reduces based on the corruption perception levels during the sampling period while the economic expansion's effect on emission levels is positive. Additionally, urbanization, trade levels and energy use all aggravate the emission levels. On the other hand, although FDI poses an insignificant environmental damage in the short run, its environmental sustainability enhancement roles were supported by its long-run negative impacts on carbon emission. Lastly, the EKC was established and as such, essential policy directions were provided for stakeholders in the rapidly emerging Malaysian economy.
    MeSH terms: Environmental Pollution/analysis; Investments; Internationality; Economic Development*
  20. Mitigation of 3-monochloropropane 1,2 diol ester and glycidyl ester in refined oil - A review
    Yung YL, Lakshmanan S, Kumaresan S, Chu CM, Tham HJ
    Food Chem, 2023 Dec 15;429:136913.
    PMID: 37506659 DOI: 10.1016/j.foodchem.2023.136913
    The 3-Monochloropropane-1, 2-diol ester (3-MCPDE) and glycidyl ester (GE) are formed at high processing temperatures with the presence of respective precursors. Both are potentially harmful to humans, causing adverse health impacts including kidney damage, reproductive problems, and increased risk of cancer. The presence of 3-MCPDE and GE in palm oil is of particular concern because of its widespread use by the food industry. There are a variety of methods for reducing 3-MCPDE and GE. For example, water washing eliminates mostly inorganic chlorides that, in turn, reduce the formation of 3-MCPDE. 3-MCPDE has also been reduced by up to 99% using combinations of methods and replacing stripping steam with alcohol-based media. Activated carbon, clay, antioxidants, potassium-based salts, and other post-refining steps have positively lowered GE, ranging from 10 to 99%. Several approaches have been successful in reducing these process contaminants without affecting other quality metrics.
    MeSH terms: Food-Processing Industry; Humans; Plant Oils
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