Displaying publications 1 - 20 of 134 in total

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  1. Zulkipli NN, Zakaria R, Long I, Abdullah SF, Muhammad EF, Wahab HA, et al.
    Molecules, 2020 Sep 02;25(17).
    PMID: 32887218 DOI: 10.3390/molecules25173991
    Natural products remain a popular alternative treatment for many ailments in various countries. This study aimed to screen for potential mammalian target of rapamycin (mTOR) inhibitors from Malaysian natural substance, using the Natural Product Discovery database, and to determine the IC50 of the selected mTOR inhibitors against UMB1949 cell line. The crystallographic structure of the molecular target (mTOR) was obtained from Protein Data Bank, with Protein Data Bank (PDB) ID: 4DRI. Everolimus, an mTOR inhibitor, was used as a standard compound for the comparative analysis. Computational docking approach was performed, using AutoDock Vina (screening) and AutoDock 4.2.6 (analysis). Based on our analysis, asiaticoside and its derivative, asiatic acid, both from Centella asiatica, revealed optimum-binding affinities with mTOR that were comparable to our standard compound. The effect of asiaticoside and asiatic acid on mTOR inhibition was validated with UMB1949 cell line, and their IC50 values were 300 and 60 µM, respectively, compared to everolimus (29.5 µM). Interestingly, this is the first study of asiaticoside and asiatic acid against tuberous sclerosis complex (TSC) disease model by targeting mTOR. These results, coupled with our in silico findings, should prompt further studies, to clarify the mode of action, safety, and efficacy of these compounds as mTOR inhibitors.
  2. Zulkifli N'A, Zahir NH, Abdullah Ripain AH, Said SM, Zakaria R
    Nanoscale Adv, 2023 Jan 31;5(3):879-892.
    PMID: 36756501 DOI: 10.1039/d2na00756h
    Molybdenum disulfide (MoS2) has been attracting considerable attention due to its excellent electrical and optical properties. We successfully grew high-quality, large-area and uniform few-layer (FL)-MoS2 on p-doped gallium nitride (p-GaN) using a simplified sulfurization technique by the single-zone CVD of a Mo seed layer via E-beam evaporation. Tuning the sulfurization parameters, namely temperature and duration, has been discovered to be an effective strategy for improving MoS2 orientation (horizontally aligned and vertically aligned) and quality, which affects photodetector (PD) performance. The increase in the sulfurization temperature to 850 °C results in improved structural quality and crystallite size. However, a prolonged sulfurization duration of 60 minutes caused the degradation of the film quality. The close lattice match between p-GaN and MoS2 contributes to the excellent quality growth of deposited MoS2. Following this, an n-MoS2/p-GaN heterostructure PD was successfully built by a MoS2 position-selectivity method. We report a highly sensitive and self-powered GaN/MoS2 p-n heterojunction PD with a relatively high responsivity of 14.3 A W-1, a high specific detectivity of 1.12 × 1013 Jones, and a fast response speed of 8.3/13.4 μs (20 kHz) under a UV light of 355 nm at zero-bias voltage. Our PD exhibits superior performance to that of the previously reported MoS2/GaN p-n PD. Our findings suggest a more efficient and straightforward approach to building high-performance self-powered UV PDs.
  3. Zuharah WF, Fadzly N, Ali Y, Zakaria R, Juperi S, Asyraf M, et al.
    Trop Biomed, 2014 Jun;31(2):297-304.
    PMID: 25134898 MyJurnal
    Vector-borne diseases are still rife because of the re-emergence of diseases transmitted by mosquitoes. The objective of this paper is to evaluate the larvicidal efficacy of crude leaf extract of Mangifera indica, Gluta renghas, and Melanochyla fasciculiflora against vector of dengue hemorrhagic fever, Aedes aegypti. These plant species are endemic species and widely distributed in Malaysian forests. Leaves of Ma. indica, G. renghas and M. fascculiflora were collected from Teluk Bahang National Park, Penang Malaysia. Fractions of leaves were segregated, air-dried, powdered and extracted using Soxhlet with methanol. The solvent was removed by using rotary evaporator to obtain the crude extract. Using WHO standard larval bioassay test method, third instar larvae of Aedes aegypti were exposed to concentration ranging from 200- 4500 ppm of methanol extract for all plant species. Larval mortality was observed after 24 hours exposure. The highest susceptibility and toxicity was recorded by Mangifera indica with the lowest concentration at 800 ppm followed by M. fasciculiflora and G. renghas. This indicates that crude plant extract is very effective in killing Ae. aegypti mosquitoes. This finding may lead to new low cost alternative, environmentally friendly method for mosquito control programs. To our knowledge, this is the first report on larvicidal bioefficacy from endemic Malaysian plants.
  4. Zamri NA, Ghani N, Ismail CAN, Zakaria R, Shafin N
    Front Aging Neurosci, 2022;14:1092596.
    PMID: 36733498 DOI: 10.3389/fnagi.2022.1092596
    Since ancient times, honey has been employed in many aspects of everyday life, the most popular of which is as a natural sweetener. Honey is used not only as a nutritional product but also in health as a supplement and in various applications, especially related to brain booster health. Brain health is the capacity to carry out all mental functions necessary for cognition, such as learning and judging, utilizing language, and recalling. This review presents the current trend of research on honey, particularly the interest in underlying mechanisms related to brain booster health. A total of 34 original articles addressing brain health from the consumption of honey were analyzed. We identified four main brain health benefits, which are memory booster, neuroprotective effect, anti-stress, and anti-nociceptive potentials with the proposed underlying mechanism. A lot of attention has been paid to the role that honey plays in brain health research, with the goal of examining the link between honey and brain health as well as the mechanism underlying it, the findings from this review may be potentially beneficial to develop new therapeutic roles for honey to help determine the best and most promising to benefit and boost overall brain health.
  5. Zakaria WNA, Yoon SY, Wijaya A, Ahmad AH, Zakaria R, Othman Z
    Eur J Hum Genet, 2023 Oct;31(10):1181-1184.
    PMID: 37142766 DOI: 10.1038/s41431-023-01371-3
    This article seeks to highlight the most recent trends and themes in genetic counseling that are of broad interest. A total of 3505 documents were published between 1952 and 2021, with a trend toward increase in paper/year. The most common documents are original articles (2515, 71.8%), followed by review articles (341, 9.7%). Journal of Genetic Counseling publishes the highest number of genetic counseling articles (587, 16.7%), followed by Clinical Genetics (103, 2.9%) and the South American Journal of Medical Genetics (95, 2.7%). Co-occurrence analysis revealed five research themes: genetic testing, cancer, genetic counselor, prenatal diagnosis, and psychiatry. The genetic counselor theme contained most of the recent keywords, including "covid-19," "underrepresented population," "service delivery models," "workforce," "disparities," "service delivery," "professional development," "cultural competence," "access," "diversity," "telemedicine," and "health literacy." Genetic counseling researchers may use these keywords to find topics pertinent to their future research and practice.
  6. Zakaria WNA, Sasongko TH, Al-Rahbi B, Al-Sowayan N, Ahmad AH, Zakaria R, et al.
    Psychiatr Genet, 2023 Apr 01;33(2):37-49.
    PMID: 36825838 DOI: 10.1097/YPG.0000000000000336
    This study aimed to perform a bibliometric analysis on genetic studies in schizophrenia in the pregenome-wide association studies (GWAS) and post-GWAS era. We searched the literature on genes and schizophrenia using the Scopus database. The documents increased with time, especially after the human genome project and International HapMap Project, with the highest citation in 2008. The top occurrence author keywords were discovered to be different in the pre-GWAS and post-GWAS eras, reflecting the progress of genetic studies connected to schizophrenia. Emerging keywords highlighted a trend towards an application of precision medicine, showing an interplay of environmental exposures as well as genetic factors in schizophrenia pathogenesis, progression, and response to therapy. In conclusion, the gene and schizophrenia literature has grown rapidly after the human genome project, and the temporal variation in the author keywords pattern reflects the trend of genetic studies related to schizophrenia in the pre-GWAS and post-GWAS era.
  7. Zakaria WNA, Wijaya A, Al-Rahbi B, Ahmad AH, Zakaria R, Othman Z
    Psychiatr Genet, 2023 Jun 01;33(3):102-112.
    PMID: 36825833 DOI: 10.1097/YPG.0000000000000338
    This study aims to use a bibliometric technique to evaluate the scientific output of gene and bipolar disorder research. The search query related to gene and bipolar disorder from the Scopus database identified 1848 documents from 1951 to 2020. The growth in the publications increased since early 1990, peaked in 2011, and started to decline thereafter. High occurrence in author keywords suggests that some research topics, such as "polymorphism", "linkage" and "association study" have waned over time, whereas others, such as "DNA methylation," "circadian rhythm," "" and "meta-analysis," are now the emerging trends in gene and bipolar disorder research. The USA was the country with the highest production followed by the UK, Canada, Italy and Germany. The leading institutions were Cardiff University in the UK, the National Institute of Mental Health (NIMH) in the USA, King's College London in the UK and the University of California, San Diego in the USA. The leading journals publishing gene and bipolar literature were the American Journal of Medical Genetics Neuropsychiatric Genetics, Molecular Psychiatry and Psychiatric Genetics. The top authors in the number of publications were Craddock N, Serretti A and Rietschel M. According to the co-authorship network analysis of authors, the majority of the authors in the same clusters were closely linked together and originated from the same or neighbouring country. The findings of this study may be useful in identifying emerging topics for future research and promoting research collaboration in the field of genetic studies related to bipolar disorder.
  8. Zakaria R, Rajikin MH, Yaacob NS, Nor NM
    Reprod Biol, 2007 Mar;7(1):41-53.
    PMID: 17435832
    The possible role of insulin-like growth factors (IGFs) and their receptors (IGFRs) in the pathogenesis of diabetic embryopathy was investigated. Sexually mature female ICR mice of 6-8 weeks old were made diabetic by a single intraperitoneal injection with 200 mg/kg streptozotocin ten days prior to mating. Fallopian tubes and uterine tissues were obtained from the superovulated diabetic and normal mice 48, 72 and 96 hours following human chorionic gonadotropin (hCG) injection. The mRNA expression of IGF-1 and IGF-2 as well as their receptors was determined in the tissues using Real-time Polymerase Chain Reaction (Real-time PCR). The mRNA expression of IGF-1 in the fallopian tube and uterus of the diabetic mice was significantly lower 72 and 96 hours after hCG treatment, respectively, as compared to the controls. The mRNA expression of IGF-1R at 96 hours post-hCG treatment was significantly higher in the fallopian tube and lower in the uterus of the diabetic mice as compared to the controls. The mRNA expression IGF-2 in the fallopian tube was significantly higher 48 and 96 hours after hCG treatment, but was lower in the uterus of diabetic mice 96 hours after hCG treatment as compared to controls. The mRNA expression of IGF-2R in the diabetic mice was significantly higher 48 and 96 hours (the fallopian tube) and 48 hours (uterus) after hCG treatments as compared to the controls. In conclusion, an alteration in mRNA expression of IGFs and their receptors in the diabetic mice as observed in this study could possibly result in diabetic embryopathy.
  9. Zakaria R, Ismail Z, Chatterjee A
    Pharmacol Res, 2000 Aug;42(2):183-6.
    PMID: 10887050
    Reproductive dysfunction in the female diabetic rat is associated with impaired hypothalamic-hypophyseal system, anovulation, insufficiency of ovarian steroidogenesis and spontaneous failure of pregnancy. Formation of decidua, the highly modified endometrium of pregnancy and pseudopregnancy could only be achieved when the uterus was sensitized by a sequence of oestrogen and progesterone. In this study, we examined whether the impaired expression of endometrial decidualization in the pseudopregnant rat is linked with diabetes-associated hypersecretion of testosterone. Rats were made pseudopregnant by sterile mating. Diabetes was induced by streptozotocin on day 1 p.c. Deciduogenic stimulus was given on day 5 p.c. Treatment of cyproterone acetate (10 mg kg(-1)) was scheduled from day 5 through day 9 p.c. Animals were killed on day 10 p.c, and the degree of endometrial decidual growth, plasma levels of oestradiol, progesterone, ACTH and testosterone were determined. Results showed that compared to controls there was a concomitant drop in endometrial decidual growth concurrently with impaired levels of oestradiol and progesterone in diabetic pseudopregnant rats. ACTH and testosterone levels were, however, profoundly elevated. Cyproterone acetate treatment in the diabetic pseudopregnant rat resulted in a simultaneous elevation of oestradiol and progesterone, which eventually helped the endometrial differentiation to decidua in the diabetic pseudopregnant rat parallel to controls. Present experimental data suggest that diabetes-associated impaired endometrial decidualization in the pseudopregnant rat is possibly caused by testosterone-induced oestrogen deficiency.
  10. Zakaria R, Zainuddin NAM, Leong TC, Rosli R, Rusdi MF, Harun SW, et al.
    Micromachines (Basel), 2019 Jul 11;10(7).
    PMID: 31336745 DOI: 10.3390/mi10070465
    In this paper, we report the effects of a side-polished fiber (SPF) coated with titanium (Ti) films in different thicknesses, namely 5 nm, 13 nm, and 36 nm, protected by a thin layer of transition metal dichalcogenides (TMDCs) such as molybdenum disulfide (MoS2) and tungsten disulfide (WS2), which provide ultra-sensitive sensor-based surface plasmon resonance (SPR) covering from the visible to mid-infrared region. The SPF deposited with Ti exhibits strong evanescent field interaction with the MoS2 and WS2, and good optical absorption, hence resulting in high-sensitivity performance. Incremental increases in the thickness of the Ti layer contribute to the enhancement of the intensity of transmission with redshift and broad spectra. The findings show that the optimum thickness of Ti with 36 nm combined with MoS2 causes weak redshifts of the longitudinal localized surface plasmon resonance (LSPR) mode, while the same thickness of Ti with WS2 causes large blueshifts. The redshifts are possibly due to a reduced plasmon-coupling effect with the excitonic region of MoS2. The observed blueshifts of the LSPR peak position are possibly due to surface modification between WS2 and Ti. Changing the relative humidity from 58% to 88% only elicited a response in Ti/MoS2. Thus, MoS2 shows more sensitivity on 36-nm thickness of Ti compared with WS2. Therefore, the proposed fiber-optic sensor with integration of 2D materials is capable of measuring humidity in any environment.
  11. Zakaria R, Harif N, Al-Rahbi B, Aziz CBA, Ahmad AH
    Oman Med J, 2019 Jan;34(1):44-48.
    PMID: 30671183 DOI: 10.5001/omj.2019.07
    Objectives: Overweight and obesity are known to cause various patterns of alteration to the pulmonary function test (PFT) parameters. We sought to investigate gender differences in PFT parameters and examine the relationship between body mass index (BMI) and PFT parameters.
    Methods: We conducted a retrospective study of 126 patients referred for a PFT by various medical specialties between January and December 2015. PFT was measured using spirometry, and BMI was calculated using Quetelet's index.
    Results: Female patients exhibited lower mean values for all PFT parameters compared to male patients. The forced vital capacity (FVC)% predicted was less than 80% for all patients while the ratio of forced expiratory volume in 1 second (FEV1)/FVC was higher with increased BMI. BMI was positively correlated with peak expiratory flow in all patients, and with FEV1/FVC ratio in males but not in females.
    Conclusions: In our studied population, males exhibited higher mean values of PFT parameters than females. Increased BMI may be associated with a restrictive pattern on spirometry.
  12. Zakaria R, Sutan R, Jaafar R
    PMID: 32642469 DOI: 10.4103/jehp.jehp_497_19
    INTRODUCTION: Educating a mother of a premature baby and providing a structured written educational information can enhance better understanding and practice. This article describes the development and implementation of a health educational package for preemie moms in the care of their premature baby after neonatal intensive care unit discharge.

    SUBJECTS AND METHODS: The package known as "Preemie Mom: A Guide for You" was designed based on Stufflebeam's model and has four phases: (1) content evaluation from available sources of information, (2) input evaluation based on mothers' need related to premature baby care, (3) process evaluation for package designing and content drafting, and (4) product evaluation to determine its feasibility. The contents were extracted and collated for validation by consulting various specialists in related fields. A final draft was drawn based on comments given by experts. Comments from the mothers were taken for formatting, visual appearance, and content flow for easy understanding and usage.

    RESULTS: All ten existing articles and eight relevant documents were gathered and critically appraised. The package was designed based on 11 main components related to the care of premature baby after discharge. The content validation was accepted at a minimum score of 0.85 for the item-level content validity index analysis. Both experts and mothers were agreed that the package is easy to use and well accepted as a guide after discharge. The agreement rate by the mothers was at 93.33% and greater for the front page, writing style, structure, presentation, and motives of the package.

    CONCLUSIONS: "Preemie Mom: A Guide for You" is a validated health educational package and ready to be used to meet the needs of the mother for premature baby care at home.

  13. Zakaria R, Rajikin MH, Yaacob NS, Nor NM
    Acta Histochem, 2009;111(1):52-60.
    PMID: 18676006 DOI: 10.1016/j.acthis.2008.04.002
    The aim of the present study was to analyze the immunolocalization of insulin-like growth factor (IGF)-1 and IGF-2 and their receptors in the oviduct and uterus of control and diabetic mice. Sexually mature female ICR mice aged 6-8 weeks were rendered diabetic by streptozotocin (200 mg/kg, administered intraperitoneally). Oviductal and uterine tissues were obtained from the superovulated control and diabetic mice at 48, 72 and 96 h post-human chorionic gonadotropin (hCG) treatment. Localization of IGF-1, IGF-2, IGF-1R and IGF-2R was determined by immunohistochemistry and a semi-quantitative scoring of immunolabelling was performed using a standardized 5-point system. The immunohistochemical scorings for both IGF-1 and IGF-1R were significantly decreased in the oviducts of diabetic mice at 96 h post-hCG treatment. The scores for IGF-2 were significantly increased in the oviducts of diabetic mice at 48 and 72 h post-hCG treatment, and for IGF-2R at 72 h post-hCG treatment. However, there was no significant difference in the scores of IGFs and their receptors in the uterus of control and diabetic mice. In conclusion, the oviductal immunolabelling for IGFs and their receptors was significantly altered by maternal diabetes, which may be of importance in the pathogenesis of preimplantation diabetic embryopathy.
  14. Zakaria R, Ahmi A, Ahmad AH, Othman Z
    Chronobiol Int, 2021 01;38(1):27-37.
    PMID: 33164592 DOI: 10.1080/07420528.2020.1838534
    This study presents a bibliometric analysis of the publications on melatonin research from the Scopus database during the period 2015-2019. Based on the keywords used, which are related to melatonin in the article title, the study retrieved 4411 documents for further analysis using various tools. We used Microsoft Excel to conduct the frequency analysis, VOSviewer for data visualization, and Harzing's Publish or Perish for citation metrics and analysis. This study reports the results using standard bibliometric indicators such as the growth of publications, authorship patterns, collaboration, and prolific authors, country contribution, most active institutions, preferred journals, and top-cited articles. Based on our findings, there is a continuous growth of publications on melatonin research for 5 years since 2015. China was the largest contributor to melatonin research, followed by the United States. The Journal of Pineal Research published the most number of publications related to melatonin research. Our findings suggest that the role of melatonin in plant and food sciences, as well as in cancer, may in later years take over the clusters that earlier dominated melatonin research.
  15. Zakaria R, Wan Yaacob WM, Othman Z, Long I, Ahmad AH, Al-Rahbi B
    Physiol Res, 2017 09 22;66(4):553-565.
    PMID: 28406691
    Alzheimer's disease (AD) is a primary cause of dementia in the middle-aged and elderly worldwide. Animal models for AD are widely used to study the disease mechanisms as well as to test potential therapeutic agents for disease modification. Among the non-genetically manipulated neuroinflammation models for AD, lipopolysaccharide (LPS)-induced animal model is commonly used. This review paper aims to discuss the possible factors that influence rats' response following LPS injection. Factors such as dose of LPS, route of administration, nature and duration of exposure as well as age and gender of animal used should be taken into account when designing a study using LPS-induced memory impairment as model for AD.
  16. Zakaria R, Yusoff SFAZ, Law KC, Lim CS, Ahmad H
    Nanoscale Res Lett, 2017 Dec;12(1):50.
    PMID: 28101853 DOI: 10.1186/s11671-016-1793-y
    In this report, we experimentally investigate the formation of "flower-like silver structures" on graphene. Using an electrochemical deposition technique with deposition times of 2.5 and 5 min, agglomerations of silver nanoparticles (AgNPs) were deposited on the graphene surfaces, causing the formation of "flower-like structures" on the graphene substrate. Localized surface plasmon resonance (LSPR) was observed in the interaction between the structures and the graphene substrate. The morphology of the samples was observed using a field-emission scanning electron microscope (FESEM) and Raman spectroscopy. Thereafter, the potential of the flower-like Ag microstructures on graphene for use in Raman spectroscopic applications was examined. The signal showed a highest intensity value after a deposition time of 5 min, as portrayed by the intense local electromagnetic fields. For a better understanding, the CST Microwave Studio software, based on the finite element method (FEM), was applied to simulate the absorption characteristics of the structures on the graphene substrate. The absorption peak was redshifted due to the increment of the nanoparticle size.
  17. Zakaria R, Ahmad AH, Othman Z
    Folia Biol. (Praha), 2016;62(5):181-187.
    PMID: 27978412
    Pineal melatonin biosynthesis is regulated by the circadian clock located in the suprachiasmatic nucleus of the hypothalamus. Melatonin has been found to modulate the learning and memory process in human as well as in animals. Endogenous melatonin modulates the process of newly acquired information into long-term memory, while melatonin treatment has been found to reduce memory deficits in elderly people and in various animal models. However, the mechanisms mediating the enhancing effect of melatonin on memory remain elusive. This review intends to explore the possible mechanisms by looking at previous data on the effects of melatonin treatment on memory performance in rodents.
  18. Zakaria R, Bawon P, Lee SH, Salim S, Lum WC, Al-Edrus SSO, et al.
    Polymers (Basel), 2021 Oct 12;13(20).
    PMID: 34685253 DOI: 10.3390/polym13203494
    The study investigated the effects of the addition of starch on the properties of oil palm biomass particleboard bonded with citric acid. Three kinds of oil palm biomasses were used in this study for the fabrication of particleboard, namely, oil palm frond (OPF), oil palm trunk (OPT), and empty fruit bunch (EFB) particles. Citric acid and tapioca starch at the mixing ratios of 100:0, 87.5:12.5, and 75:25 were prepared at a 60% solid content. A 30% resin content based on the oven-dried weight of the oil palm biomass particles was used. The sprayed particles were pre-dried at 80 °C for 12 h before being hot-pressed at 180 °C and 4 MPa pressure for 10 min. The physical and mechanical properties of the particleboard were evaluated. The mixtures of citric acid and tapioca starch were characterized by thermogravimetric analysis (TGA). Thermal stability of citric acid was reduced after the addition of tapioca starch. The addition of 12.5% tapioca starch improved the bending strength of the particleboard but increased the thickness swelling slightly. All UF-bonded particleboard exhibited significantly inferior performance than that of citric-acid-bonded particleboard. Citric-acid-bonded particleboard maintained its original shape after being subjected to a cyclic-aging treatment, while the UF-bonded particleboard disintegrated half way through the treatment. The performance of EFB particleboard was significantly inferior to its OPT and OPF counterparts.
  19. Yusof AM, Mohammad M, Abdullahi MA, Mohamed Z, Zakaria R, Wahab RA
    Trop Life Sci Res, 2017 Jan;28(1):23-32.
    PMID: 28228914 MyJurnal DOI: 10.21315/tlsr2017.28.1.2
    Intestinal parasitic infections are one of the most common causes of human diseases that result in serious health and economic issues in many developing and developed countries. Raw vegetables and fruits play an important role in transmitting parasites to humans. Hence, the aim of this study was to investigate the parasitological contamination of select commonly consumed local leafy vegetables and fruits in Kuantan, Malaysia. One kilogram of locally consumed raw vegetables and fruits were collected randomly from the Kuantan wet market (Pasar Tani) during the monsoon season (November 2014-January 2015) and the dry season (February 2015-April 2015). A standard wet mount procedure and modified Ziehl-Neelsen staining were used for the detection of parasites. In the present study, the examination of vegetables revealed five different parasite species. The vegetable samples collected from Kuantan's wet market were positive for both helminthes and protozoa. However, the fruits samples were negative for parasitic contamination. Pegaga was the most contaminated leafy vegetable in this study, and Strongyloides was the parasite found most frequently. Furthermore, there was a high diversity in the type of parasites observed during the dry season compared to the monsoon season. Therefore, further action should be taken to reduce the occurrence of parasitic contamination in vegetables by implementing the principles of good agricultural practice and improving water treatment efficacy.
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