Displaying publications 121 - 140 of 250 in total

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  1. Rahmani M, Ahmadi MT, Abadi HK, Saeidmanesh M, Akbari E, Ismail R
    Nanoscale Res Lett, 2013;8(1):55.
    PMID: 23363692 DOI: 10.1186/1556-276X-8-55
    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.
  2. Loo Ch, Basri M, Ismail R, Lau H, Tejo B, Kanthimathi M, et al.
    Int J Nanomedicine, 2013;8:13-22.
    PMID: 23293516 DOI: 10.2147/IJN.S35648
    To study the effects of varying lipid concentrations, lipid and oil ratio, and the addition of propylene glycol and lecithin on the long-term physical stability of nanostructured lipid nanocarriers (NLC), skin hydration, and transepidermal water loss.
  3. Kwan Z, Wong SM, Robinson S, Tan LL, Looi LM, Ismail R
    Ann Acad Med Singap, 2015 Dec;44(12):577-9.
    PMID: 27090079
  4. Che Dom N, Faiz Madzlan M, Nadira Yusoff SN, Hassan Ahmad A, Ismail R, Nazrina Camalxaman S
    Trans R Soc Trop Med Hyg, 2016 Apr;110(4):237-45.
    PMID: 27076510 DOI: 10.1093/trstmh/trw015
    Dengue fever (DF) is an urban vector-borne disease transmitted by Aedes aegypti and Aedes albopictus. Both species deposit their eggs in favorable breeding sites either in natural or artificial containers. An understanding of their habitat characteristics is crucial in curbing DF outbreaks
  5. Zahari Z, Siong LC, Musa N, Mohd Yasin MA, Choon TS, Mohamad N, et al.
    Pak J Pharm Sci, 2016 Jan;29(1):239-46.
    PMID: 26826835
    Poor sleep quality was frequently reported by opioid dependence patients during methadone maintenance therapy (MMT). The study investigated a sample of patients on MMT to investigate the severity and prevalence of sleep problems in MMT patients. We evaluated sleep quality and disturbances of 119 Malay male patients from MMT clinics in Kelantan, Malaysia between March and July 2013 using the Pittsburgh Sleep Quality Index (PSQI)-Malay version. Patients' demographic, clinical data, past drug history and methadone treatment variables were recorded. Patients averaged 37.5 years of age (SD 6.79) and their mean age of first time illicit drug use was 19.3 years (SD 4.48). Their mean age of entering MMT was 34.7 years (SD 6.92) and the mean duration in MMT was 2.8 years (SD 2.13). The mean current daily dosage of methadone was 77.8 mg (SD 39.47) and ranged from 20 to 360 mg. The mean global PSQI score was 5.6 (SD 2.79) and 43.7% patients were identified as 'poor sleepers' (global PSQI scores >5). This study confirms the poor overall sleep quality among patients on MMT. The prevalence and severity of sleep problems in MMT patients should not be underestimated.
  6. Ahmad N, MuhdYusoff F, Ratnasingam S, Mohamed F, Nasir NH, MohdSallehuddin S, et al.
    PMID: 26000035
    Studying trends in mental health morbidity will guide the planning of future interventions for mental and public health services. To assess the trends in mental health problems among children and adolescents aged 5 through 15 years in Malaysia from 1996 to 2011, data from the children's mental health component of three population-based surveys was analysed using a two-stage stratified sampling design. Mental health problems were assessed using the Reporting Questionnaire for Children. The prevalence of mental health problems among children and adolescents aged 5 through 15 years showed an increasing trend from 13.0% (95% Confidence Interval [CI]: 11.5-14.6) in 1996 to 19.4% (95% CI: 18.5-20.3) in 2006 and 20.0% (95% CI: 18.8-21.3) in 2011. In 2011, male children and adolescents and those who were in less affluent families were significantly associated with mental health problems. The findings indicate that even though mental health problems among children and adolescents in Malaysia are increasing, the rate of increase has decreased in the past five years. Socially and economically disadvantaged groups were most vulnerable to mental health problems.
  7. Ibrahim N, Teo SS, Che Din N, Abdul Gafor AH, Ismail R
    PLoS One, 2015;10(7):e0129015.
    PMID: 26131714 DOI: 10.1371/journal.pone.0129015
    BACKGROUND: Chronic kidney disease (CKD) is commonly associated with various negative health outcomes. The aim of this study was to examine the influence of personality and social support on health-related quality of life in patients with chronic kidney disease. Health-related quality of life (HRQoL) is the quality of life studied in relation to health, and it provides important information of patients' coping with their health issues.

    METHOD: Participants comprised of 200 patients experiencing various stages of chronic kidney disease. All participants completed the Short-Form 36 (SF-36), Big Five Inventory (BFI) and the Medical Outcomes Study (MOS) Social Support questionnaires.

    RESULTS: Participants consisted of 108 males (54.0%) and 92 females (46.0%) with the mean age of 59.3 years (SD 14.5). Results showed that higher levels of extraversion and lower perceived affectionate social support were associated with higher physical HRQoL, whereas higher levels of neuroticism were associated with poorer mental HRQoL.

    CONCLUSION: The current study found that certain personality traits, namely extraversion and neuroticism, were found to be associated with HRQoL. In addition, affectionate social support was also associated with higher HRQoL. Therefore, special attention should be paid to the personality of CKD patients, as well as the type of social support that they have, in planning interventions to improve their health outcomes.

  8. Zahari Z, Lee CS, Tan SC, Mohamad N, Lee YY, Ismail R
    PeerJ, 2015;3:e839.
    PMID: 25870765 DOI: 10.7717/peerj.839
    Aim. Poor sleep quality due to pain has been reported among opioid-dependent male patients on methadone maintenance therapy (MMT) but objective pain data are lacking. This study aimed to investigate the rate of pain-sensitivity using cold pressor test (CPT) and the relationship between pain-sensitivity and sleep quality in this population.
    Methods. A total of 168 male participants were included into the study. Objective pain-tolerance was evaluated at 0 h and at 24 h after the first CPT. Malay version of the Pittsburgh Sleep Quality Index (PSQI) and the subjective opiate withdrawal scale (SOWS) questionnaires were administered to evaluate the quality of sleep and withdrawal symptoms, respectively.
    Results. The mean age of study participants was 37.22 (SD 6.20) years old. Mean daily methadone dose was 76.64 (SD 37.63) mg/day, mean global PSQI score was 5.47 (SD 2.74) and mean averaged SOWS score was 5.43 (SD 6.91). The averaged pain-tolerance time ranged from 7 to 300 s with a mean time of 32.16 (SE 2.72) s, slightly below the cut-off score of 37.53 s. More specifically, 78.6% (n = 132) of participants were identified as pain-sensitive (averaged pain-tolerance time ≤37.53 s), and 36 (21.4%) participants were pain-tolerant (averaged pain-tolerance time >37.53 s). The pain-sensitive group reported poorer sleep quality with mean (SD) PSQI of 5.78 (2.80) compared with the pain-tolerant group with mean (SD) PSQI of 4.31 (2.18) (p = 0.005). With analysis of covariance, pain-sensitive group was found to have higher global PSQI scores (adjusted mean 5.76, 95% CI 5.29; 6.22) than pain-tolerant participants (adjusted mean 4.42, 95% CI 3.52; 5.32) (p = 0.010).
    Conclusions. Majority of opioid-dependent male patients on methadone treatment are pain-sensitive with CPT. Poor sleep quality is associated with cold pressor pain-sensitivity. Pain and sleep complaints in this male population should not be overlooked.
    Study site: Hospital Universiti Sains Malaysia (HUSM) and other MMT clinics (Kota Bharu, Pasir Mas, Pasir Puteh and Bachok), Kelantan, Malaysia
  9. Mustafa AN, Gessner BD, Ismail R, Yusoff AF, Abdullah N, Ishak I, et al.
    Int J Infect Dis, 2003 Sep;7(3):210-4.
    PMID: 14563225
    To determine influenza vaccine effectiveness against clinically defined influenza-like illness among Malaysian pilgrims attending the Haj in Saudi Arabia.
  10. Panchanathan V, Kumar S, Yeap W, Devi S, Ismail R, Sarijan S, et al.
    Bull World Health Organ, 2001;79(9):811-7.
    PMID: 11584728
    To carry out a comparative study of the safety and immunogenicity of Vi polysaccharide vaccine against whole-cell killed (WCK) typhoid vaccine.
  11. Pan Y, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, Ong CE
    Protein J, 2011 Dec;30(8):581-91.
    PMID: 22001938 DOI: 10.1007/s10930-011-9365-6
    This study aimed to express two major drug-metabolizing human hepatic cytochromes P450 (CYPs), CYP2D6 and CYP3A4, together with NADPH-cytochrome P450 oxidoreductase (OxR) in Escherichia coli and to evaluate their catalytic activities. Full length cDNA clones of both isoforms in which the N-terminus was modified to incorporate bovine CYP17α sequence were inserted into a pCWori(+) vector. The modified CYP cDNAs were subsequently expressed individually, each together with OxR by means of separate, compatible plasmids with different antibiotic selection markers. The expressed proteins were evaluated by immunoblotting and reduced CO difference spectral scanning. Enzyme activities were examined using high performance liquid chromatography (HPLC) assays with probe substrates dextromethorphan and testosterone for CYP2D6 and CYP3A4, respectively. Results from immunoblotting demonstrated the presence of both CYP proteins in bacterial membranes and reduced CO difference spectra of the cell preparations exhibited the characteristic absorbance peak at 450 nm. Co-expressed OxR also demonstrated an activity level comparable to literature values. Kinetic parameters, K(m) and V(max) values determined from the HPLC assays also agreed well with literature values. As a conclusion, the procedures described in this study provide a relatively convenient and reliable means of producing catalytically active CYP isoforms suitable for drug metabolism and interaction studies.
  12. Napi MLM, Sultan SM, Ismail R, How KW, Ahmad MK
    Materials (Basel), 2019 Sep 15;12(18).
    PMID: 31540160 DOI: 10.3390/ma12182985
    Electrochemical biosensors have shown great potential in the medical diagnosis field. The performance of electrochemical biosensors depends on the sensing materials used. ZnO nanostructures play important roles as the active sites where biological events occur, subsequently defining the sensitivity and stability of the device. ZnO nanostructures have been synthesized into four different dimensional formations, which are zero dimensional (nanoparticles and quantum dots), one dimensional (nanorods, nanotubes, nanofibers, and nanowires), two dimensional (nanosheets, nanoflakes, nanodiscs, and nanowalls) and three dimensional (hollow spheres and nanoflowers). The zero-dimensional nanostructures could be utilized for creating more active sites with a larger surface area. Meanwhile, one-dimensional nanostructures provide a direct and stable pathway for rapid electron transport. Two-dimensional nanostructures possess a unique polar surface for enhancing the immobilization process. Finally, three-dimensional nanostructures create extra surface area because of their geometric volume. The sensing performance of each of these morphologies toward the bio-analyte level makes ZnO nanostructures a suitable candidate to be applied as active sites in electrochemical biosensors for medical diagnostic purposes. This review highlights recent advances in various dimensions of ZnO nanostructures towards electrochemical biosensor applications.
  13. Davis TM, Singh B, Choo KE, Ibrahim J, Sulaiman SA, Kadir ZA, et al.
    J Intern Med, 1998 May;243(5):349-54.
    PMID: 9651556
    OBJECTIVES: To investigate the dynamic parathyroid response to rapidly induced, sustained hypocalcaemia in patients with acute malaria and in healthy volunteers.

    DESIGN: Serum intact parathormone (PTH) concentrations were measured on samples taken before and during a variable-rate tri-sodium citrate infusion designed to 'clamp' the whole blood ionised calcium concentration 0.20 mmol L-1 below baseline for 120 min.

    SUBJECTS: Six Malaysian patients aged 17-42 years with acute malaria, four of whom were restudied in convalescence, and 12 healthy controls aged 19-36 years.

    MAIN OUTCOME MEASURES: Whole-blood ionised calcium and serum intact PTH concentrations.

    RESULTS: The mean (SD baseline ionised calcium was lower in the malaria patients than in controls (1.09 +/- 0.06 vs. 1.18 +/- 0.03 mmol L-1, respectively; P = 0.01) but PTH concentrations were similar (3.0 +/- 1.8 vs. 3.3 +/- 1.3 pmol L(-1); P = 0.33). Target whole-blood ionised calcium concentrations were achieved more rapidly in the controls than the patients (within 15 vs. 30 min) despite significantly more citrate being required in the patients (area under the citrate infusion-time curve 0.95 (0.25 vs. 0.57 +/- 0.09 mmol kg-1; P < 0.01). The ratio of the change in serum PTH to that in ionised calcium (delta PTH/ delta Ca2+), calculated to adjust for differences in initial rate of fall of ionised calcium, was similar during the first 5 min of the clamp (132 +/- 75 x 10(-6) vs. 131 +/- 43 x 10(-6) in patients and controls, respectively, P > 0.05), as were steady-state serum PTH levels during the second hour (7.0 +/- 2.2 pmol L-1 in each case). Convalescent patients had normal basal ionised calcium levels but the lowest serum intact PTH levels before and during the clamp, consistent with an increase in skeletal PTH sensitivity after treatment.

    CONCLUSIONS: There is a decreased ionised calcium 'set point' for basal PTH secretion but a normal PTH response to acute hypocalcaemia in malaria. Skeletal resistance may attenuate the effects of the PTH response but patients with malaria appear relatively resistant to the calcium chelating effects of citrated blood products.

  14. Ismail NA, Dom NC, Ismail R, Ahmad AH, Zaki A, Camalxaman SN
    J Am Mosq Control Assoc, 2015 Dec;31(4):305-12.
    PMID: 26675451 DOI: 10.2987/moco-31-04-305-312.1
    A study was conducted to establish polymorphic variation of the mitochondrial DNA encoding the cytochrome oxidase subunit 1 (CO1) gene in Aedes albopictus isolated from 2 hot spot dengue-infested areas in the Subang Jaya District, Malaysia. A phylogenetic analysis was performed with the use of sequences obtained from USJ6 and Taman Subang Mas (TSM). Comparison of the local CO1 sequences with a laboratory strain (USM), alongside reference strains derived from the GenBank database revealed low genetic variation in terms of nucleotide differences and haplotype diversity. Four methods were used to construct a phylogenetic tree and illustrate the genetic relationship of the 37 Ae. albopictus populations based on the CO1 sequences, namely neighbor-joining (NJ), maximum parsimony (MP), maximum likelihood (ML), and Bayesian method, which revealed a distinct relationship between isolates from USJ6 and TSM. Our findings provide new information regarding the genetic diversity among morphologically similar Ae. albopictus, which has not been reported to date.
  15. Wei AC, Ali MA, Yoon YK, Ismail R, Choon TS, Kumar RS
    Bioorg Med Chem Lett, 2013 Mar 1;23(5):1383-6.
    PMID: 23352268 DOI: 10.1016/j.bmcl.2012.12.069
    A series of fourteen dispiropyrrolidines were synthesized using [3+2]-cycloaddition reactions and were screened for their antimycobacterial activity against Mycobacterium tuberculosis H(37)Rv in HTS (High Throughput Screen). Most of the compounds showed moderate to good activity with MIC of less than 20 μM. Compound 4'-(4-bromophenyl)-1'-methyldispiro[acenaphthylene-1,2'-pyrrolidine-3',2″-indane]-2,1″(1H)-dione (4c) was found to be the most active with MIC of 12.50 μM.
  16. Sulaiman HF, Ismail R, Mohd Yusoff H, Anuar N, Mohd Jamil MR, Daud F
    J Agromedicine, 2020 04;25(2):166-172.
    PMID: 31533524 DOI: 10.1080/1059924X.2019.1666763
    Objective: The Fuzzy Delphi Method (FDM) is one of the phases in Design and Development Research (DDR). It is a systematic method for tool development and validation. This article aims to validate an occupational zoonotic disease questionnaire using this technique. DDR is applied going through phase 1 (needs analysis), phase 2 (development and design), and phase 3 (usability).Method: In phase 1, information about safe work practices and occupational zoonotic exposure was obtained from discussions to verify predetermined domains as stated in The National Park Service survey on zoonotic disease exposure and risk. In phase 2, agreement from 14 experts about the domains was obtained using the FDM. In phase 3, a cognitive debriefing was performed to determine its usability for future studies. A total of five superior domains were verified, and their items were adapted. All domains and their items were submitted to experts to obtain consensus agreement.Results: A total of 31 (96.9%) passed the Triangle of Fuzzy Numbers and Defuzzification process with acceptable consensus agreement (78.8-91.9%) and threshold d value (0.07-0.14). Only four veterinarians were needed for cognitive debriefing to achieve the point of saturation.Conclusion: FDM in DDR is suitable to be applied by various professions for tool validation, as it is doable and cost and time effective. The Occupational Zoonotic Disease Questionnaire is now ready to be used for future studies in Malaysia.
  17. Selimin DS, Ismail A, Ahmad N, Ismail R, Mohd Azman NF, Azman A
    J Trop Med, 2021;2021:9923378.
    PMID: 34194511 DOI: 10.1155/2021/9923378
    Background: Tuberculosis (TB) is a serious health threat to people living with human immunodeficiency virus (HIV). This study aimed to identify the characteristics, unsuccessful TB treatment rate, and determinants of unsuccessful TB treatment outcome among patients with TB-HIV coinfection in Kuala Lumpur.

    Methods: This was a cross-sectional study. The data of all patients with TB-HIV in the federal territory of Kuala Lumpur from 2013 to 2017 were collected and reviewed. The data were retrieved from the national database (TB Information System) at the Kuala Lumpur Health Department from 1 March 2018 to 31 May 2018.

    Results: Out of 235 randomly selected patients with TB-HIV, TB treatment outcome was successful in 57.9% (cured and completed treatment) and unsuccessful in 42.1% (died, failed, or lost to follow-up). Patients who did not receive DOTS (directly observed treatment, short course) (adjusted odds ratio: 21.71; 95% confidence interval: 5.36-87.94) and those who received shorter treatment duration of <6 months (aOR: 34.54; 95% CI: 5.97-199.93) had higher odds for unsuccessful TB treatment outcome.

    Conclusions: Nearly half of the patients with TB-HIV had unsuccessful TB treatment outcome. Therefore, it is important to ensure that such patients receive DOTS and continuous TB treatment of >6 months. It is crucial to strengthen and widen the coverage of DOTS, especially among high-risk groups, in healthcare settings. Strict follow-up by healthcare providers is needed for patients with TB-HIV to gain treatment adherence and for better rates of successful TB treatment.

  18. Gan SH, Ismail R, Wan Adnan WA, Zulmi W, Kumaraswamy N, Larmie ET
    Br J Clin Pharmacol, 2004 Jun;57(6):785-9.
    PMID: 15151524
    A person with Type A personality is an 'aggressor' compared with the rarely harried Type B. Although debrisoquine hydroxylase (CYP2D6) capacity has been associated with personality, no study has specifically investigated its association with personality Type A and B. Therefore the aim of this research was to study the impact of CYP2D6 on Type A and B personality.
  19. Kanabalan RD, Lee LJ, Lee TY, Chong PP, Hassan L, Ismail R, et al.
    Microbiol Res, 2021 May;246:126674.
    PMID: 33549960 DOI: 10.1016/j.micres.2020.126674
    Mycobacterium tuberculosis complex (MTBC) refers to a group of mycobacteria encompassing nine members of closely related species that causes tuberculosis in animals and humans. Among the nine members, Mycobacterium tuberculosis (M. tuberculosis) remains the main causative agent for human tuberculosis that results in high mortality and morbidity globally. In general, MTBC species are low in diversity but exhibit distinctive biological differences and phenotypes among different MTBC lineages. MTBC species are likely to have evolved from a common ancestor through insertions/deletions processes resulting in species speciation with different degrees of pathogenicity. The pathogenesis of human tuberculosis is complex and remains poorly understood. It involves multi-interactions or evolutionary co-options between host factors and bacterial determinants for survival of the MTBC. Granuloma formation as a protection or survival mechanism in hosts by MTBC remains controversial. Additionally, MTBC species are capable of modulating host immune response and have adopted several mechanisms to evade from host immune attack in order to survive in humans. On the other hand, current diagnostic tools for human tuberculosis are inadequate and have several shortcomings. Numerous studies have suggested the potential of host biomarkers in early diagnosis of tuberculosis, in disease differentiation and in treatment monitoring. "Multi-omics" approaches provide holistic views to dissect the association of MTBC species with humans and offer great advantages in host biomarkers discovery. Thus, in this review, we seek to understand how the genetic variations in MTBC lead to species speciation with different pathogenicity. Furthermore, we also discuss how the host and bacterial players contribute to the pathogenesis of human tuberculosis. Lastly, we provide an overview of the journey of "omics" approaches in host biomarkers discovery in human tuberculosis and provide some interesting insights on the challenges and directions of "omics" approaches in host biomarkers innovation and clinical implementation.
  20. Ismail R, Allaudin ZN, Abdullah R, Mohd Lila MA, Nik Abd Rahman NM, Abdul Rahman SO
    BMC Cancer, 2016 07 13;16:461.
    PMID: 27411985 DOI: 10.1186/s12885-016-2530-8
    BACKGROUND: Cancer therapies that kill cancer cells without affecting normal cells is the ultimate mode of treating cancers. The VP3, an avian virus-derived protein, can specifically initiate cell death through several signal transduction pathways leading to apoptosis. In cancer, chemoresistance and cell survivability implicate the cell surface protein, CD147.

    METHODS: In this study, transfection of VP3 and silencing of CD147 genes was achieved through the treatment of tumors with pVIVO1-GFP/VP3 (VP3), psiRNA-CD147/2 (shCD147/2), and their combination of CT26 colon cancer cell-induced in mice. The effectiveness of tumor-treatment was ascertained by electrophoresis, TUNEL assay, and flow cytometry analysis. While histopathological and biochemical analysis were used as toxic side effect identification.

    RESULTS: The tumor growth delay index (TGDI) after treatment with VP3, shCD147/2, and their combination treatments increased by 1.3-, 1.2-, 2.0- and 2.3-fold respectively, over untreated control. The VP3-shCD147/2 combination treatment was more efficacious then either VP3 or shCD147/2 alone in the retardation of mouse CT26 colorectal cell tumor allograft.

    CONCLUSION: The antitumor effect of the combination treatment is the result of synergistic effects of VP3 and shCD147/2 on the tumor cells resulting in apoptosis. Thus, the study shows that combination of VP3 and shCD147/2 treatment can be developed into a potential approach for anticolorectal cancer treatment regimen.

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