Displaying publications 41 - 60 of 134 in total

Abstract:
Sort:
  1. Fadzly N, Zuharah WF, Mansor A, Zakaria R
    Plant Signal Behav, 2016 07 02;11(7):e1197466.
    PMID: 27315145 DOI: 10.1080/15592324.2016.1197466
    Macaranga bancana is considered as a successful pioneer plant species. Usually found in disturbed and open areas, most of the current research focused on its relations with ants. One of the unique feature of the plants is that the seedling leaves are red, resembling and almost matching the background. Using a portable spectrometer, we measured the color reflectance of M. bancana seedlings (less than 20 cm in height). We also measured the leaf litter reflectance, adult M. bancana leaves and also seedlings of several other species found in the vicinity of M. bancana seedlings. The reflectances of M. bancana seedlings are very similar to that of the leaf litter background. We suggest that this cryptic coloration is crucial during the early stages of the plant when it still cannot rely on the protection of ants.
  2. Liu K, Fadzly N, Mansor A, Zakaria R, Ruppert N, Lee CY
    Plant Signal Behav, 2017 Oct 03;12(10):e1371890.
    PMID: 28841358 DOI: 10.1080/15592324.2017.1371890
    Amorphophallus bufo is a rarely studied plant in Malaysian tropical rainforests. We measured the spectral reflectance of different developmental stages of A. bufo (seedlings, juveniles and adults), background soil/ debris and leaves from other neighboring plant species. Results show that the leaves of A. bufo seedling have a similar reflectance curve as the background soil and debris. Adults and juveniles of A. bufo are similar to other neighboring plants' leaf colors. We hypothesize that the cryptic coloration of A. bufo seedlings plays an important role in camouflage and that the numerous black spots on the surface of the petioles and rachises, may serve as a defensive mimicry against herbivores.
  3. Lam NF, Ibrahim H, Sam YY, Mohammad Zakaria R, Poulsen AD
    PhytoKeys, 2022;211:81-92.
    PMID: 36760727 DOI: 10.3897/phytokeys.211.83985
    Two new species of Boesenbergia, B.sugudensis sp. nov. and B.truncata sp. nov. were discovered in Sabah, Malaysian Borneo. Boesenbergiasugudensis resembles B.imbakensis in that the leaf sheath of the plant is not thickened and in the anther thecae dehiscing by longitudinal slits, but differs in having a longer petiole and tubular calyx. Boesenbergiatruncata resembles B.orbiculata by the short petiole and a bilobed calyx, but differs by the truncate leaf base, the acute leaf apex, opposite leaves with a narrower lamina parallel to the ground and anther thecae dehiscing by pores. The new species are described and illustrated in detail.
  4. James Antony JJ, Zakaria S, Zakaria R, Anak Ujang J, Othman N, Subramaniam S
    Physiol Mol Biol Plants, 2019 Nov;25(6):1457-1467.
    PMID: 31736548 DOI: 10.1007/s12298-019-00703-2
    Dendrobium Sabin Blue is an important orchid hybrid that has been grown extensively as cut flower, potted plant and is also popular for its deep purplish blue flowers.  The most efficient long term conservation method of this hybrid is through cryopreservation. Cryopreservation involving the vitrification method consists of explants exposure to highly concentrated cryoprotective solution followed by freezing rapidly in liquid nitrogen. However, these treatments involved highly concentrated cryoprotectant that could incur toxicity to the explants. Hence, cryopreservation protocol requires biochemical analyses in understanding the damages or injuries occurred during cryopreservation treatments. In this study, biochemical analyses revealed a general reduction in chlorophyll, carotenoid and porphyrin content to 0.40 µg/g F W (thawing stage), 31.50 µg/g F W unloading stage and 2230.41 µg/g F W (thawing stage), respectively in comparison to the control treatments. In addition, increased level in proline content were obtained at different cryopreservation stages with highest level (5.42 µmole/g F W) recorded at the PVS2 dehydration stage. Fluctuated outcomes were obtained in catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) enzyme activities in PLBs exposed to different cryopreservation stages. Lowest values recorded for CAT enzyme activity were obtained at the dehydration stage (3.94 U/g). Lowest POX enzyme activities were obtained at the dehydration (122.36 U/g) and growth recovery (106.40 U/g) stages. Additionally, lowest APX enzyme activities values were recorded at the thawing (7.47 U/g) and unloading (7.28 U/g) stages. These have contributed to low regeneration of Dendrobium Sabin Blue protocorm like bodies (PLBs) following cryopreservation. Hence, in the future experimental design, exogenous antioxidant could be included in the cryopreservation procedures to improve the existing protocol.
  5. 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.
  6. 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.
  7. Hajissa K, Zakaria R, Suppian R, Mohamed Z
    Parasit Vectors, 2015;8:315.
    PMID: 26062975 DOI: 10.1186/s13071-015-0932-0
    Serological investigation remains the primary approach to achieve satisfactory results in Toxoplasma gondii identification. However, the accuracy of the native antigen used in the current diagnostic kits has proven to be insufficient as well as difficult to standardize, so significant efforts have been made to find alternative reagents as capture antigens. Consequently, multi-epitope peptides are promising diagnostic markers, with the potential for improving the accuracy of diagnostic kits. In this study, we described a simple, inexpensive and improved strategy to acquire such diagnostic markers. The study was aimed at producing novel synthetic protein consisting of multiple immunodominant epitopes of several T. gondii antigens.
  8. Azman KF, Zakaria R, Abdul Aziz CB, Othman Z
    Oxid Med Cell Longev, 2016;2016:1549158.
    PMID: 27119005 DOI: 10.1155/2016/1549158
    Ageing and stress exposure may lead to memory impairment while oxidative stress is thought to be one of the underlying mechanisms involved. This study aimed to investigate the potential protective effects of Tualang honey supplementation on memory performance in aged rats exposed to noise stress. Tualang honey supplementation was given orally, 200 mg/kg body weight for 28 days. Rats in the stress group were subjected to loud noise, 100 dB(A), 4 hours daily for 14 days. All rats were subjected to novel object recognition test for evaluation of memory performance. It was observed that the rats subjected to noise stress exhibited significantly lower memory performance and higher oxidative stress as evident by elevated malondialdehyde and protein carbonyl levels and reduction of antioxidant enzymes activities compared to the nonstressed rats. Tualang honey supplementation was able to improve memory performance, decrease oxidative stress levels, increase brain-derived neurotrophic factor (BDNF) concentration, decrease acetylcholinesterase activity, and enhance neuronal proliferation in the medial prefrontal cortex (mPFC) and hippocampus. In conclusion, Tualang honey protects against memory decline due to stress exposure and/or ageing via enhancement of mPFC and hippocampal morphology possibly secondary to reduction in brain oxidative stress and/or upregulation of BDNF concentration and cholinergic system.
  9. 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.
  10. Mahmud KA, Zakaria R, Azman M, Mat Baki M
    ORL J Otorhinolaryngol Relat Spec, 2021 05 05;83(4):295-298.
    PMID: 33951656 DOI: 10.1159/000515424
    Adult laryngeal haemangioma is normally seen in the supraglottic or glottic region. Transglottic haemangioma is unusual, and treatment with primary endolaryngeal surgical excision may lead to undesirable bleeding and poor voice outcomes. A 25-year-old female presented with hoarseness and progressive upper airway obstruction symptoms. Videoendoscopy showed haemangioma involving all unilateral subunits of the larynx obstructing half of the subglottis. The transglottic haemangioma was treated with endolaryngeal ethanol injection with prior tracheostomy under local anaesthesia. Endolaryngeal laser surgery was performed later on to remove small residual haemangioma and granuloma. The haemangioma resolved; however, the ethanol injection to the paraglottic space results in vocal fold immobility but with favourable position and good muscle tone and bulk. The patient was successfully decannulated. Post-intervention subjective and objective voice assessments showed normal parameters except slight impairment of voice handicap index-10 with a total score of 12. Adult transglottic haemangioma can cause upper airway obstruction and requires intervention. Excision of the lesion endoscopically without sacrificing voice is achievable.
  11. Aziz CB, Omar N, Abdullah WZ, Jalil RA, Nik WS, Zakaria R
    N Am J Med Sci, 2014 Aug;6(8):377-82.
    PMID: 25210670 DOI: 10.4103/1947-2714.139286
    Obese subjects are at risk of multiple comorbidities including stroke and coronary heart disease (CHD), which is partly due to disturbances in the hemostatic system.
  12. Azman KF, Zakaria R, AbdAziz C, Othman Z, Al-Rahbi B
    Noise Health, 2015 Mar-Apr;17(75):83-9.
    PMID: 25774610 DOI: 10.4103/1463-1741.153388
    Recent evidence has exhibited dietary influence on the manifestation of different types of behavior induced by stressor tasks. The present study examined the effects of Tualang honey supplement administered with the goal of preventing or attenuating the occurrence of stress-related behaviors in male rats subjected to noise stress. Forty-eight adult male rats were randomly divided into the following four groups: i) nonstressed with vehicle, ii) nonstressed with Tualang honey, iii) stressed with vehicle, and iv) stressed with honey. The supplement was given once daily via oral gavage at 0.2 g/kg body weight. Two types of behavioral tests were performed, namely, the novel object recognition test to evaluate working memory and the forced swimming test to evaluate depressive-like behavior. Data were analyzed by a two-way analysis of variance (ANOVA) using IBM SPSS 18.0. It was observed that the rats subjected to noise stress expressed higher levels of depressive-like behavior and lower memory functions compared to the unexposed control rats. In addition, our results indicated that the supplementation regimen successfully counteracted the effects of noise stress. The forced swimming test indicated that climbing and swimming times were significantly increased and immobility times significantly decreased in honey-supplemented rats, thereby demonstrating an antidepressant-like effect. Furthermore, cognitive function was shown to be intensely affected by noise stress, but the effects were counteracted by the honey supplement. These findings suggest that subchronic exposure to noise stress induces depressive-like behavior and reduces cognitive functions, and that these effects can be attenuated by Tualang honey supplementation. This warrants further studies to examine the role of Tulang honey in mediating such effects.
  13. Abdo Qaid EY, Abdullah Z, Zakaria R, Long I
    Neurol Res, 2024 Mar;46(3):261-271.
    PMID: 38122814 DOI: 10.1080/01616412.2023.2296754
    INTRODUCTION: The neuroinflammatory response was seen to impact the formation of phosphorylated tau protein in Alzheimer's disease (AD). This study aims to investigate the molecular mechanism of minocycline in reducing phosphorylated tau protein formation in the hippocampus of lipopolysaccharide (LPS)-induced rats.

    METHODS: Fifty adult male Sprague Dawley (SD) rats were randomly allocated to 1 of 5 groups: control, LPS (5 mg/kg), LPS + minocycline (25 mg/kg), LPS + minocycline (50 mg/kg) and LPS + memantine (10 mg/kg). Minocycline and memantine were administered intraperitoneally (i.p) for two weeks, and LPS was injected i.p. once on day 5. ELISA was used to determine the level of phosphorylated tau protein in SD rats' hippocampal tissue. The density and expression of Toll-like receptor-4 (TLR-4), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-кβ), tumour necrosis factor-alpha (TNF-α), and cyclooxygenase (COX)-2 were determined using Western blot and immunohistochemistry.

    RESULTS: Minocycline, like memantine, prevented LPS-induced increasein phosphorylated tau protein level suggested via reduced density and expression of TLR-4, NF-кβ, TNF-αand COX-2 proteins in rat hippocampal tissue. Interestingly, higher doses were shown to be more neuroprotective than lower doses.

    CONCLUSION: This study suggests that minocycline suppresses the neuroinflammation signalling pathway and decreased phosphorylated tau protein formation induced by LPS in a dose-dependent manner. Minocycline can be used as a preventative and therapeutic drug for neuroinflammatory diseases such as AD.

  14. Qaid EYA, Abdullah Z, Zakaria R, Long I
    Neurochem Res, 2023 May;48(5):1480-1490.
    PMID: 36509985 DOI: 10.1007/s11064-022-03842-3
    The oxidative stress-induced dysregulation of the cyclic AMP response element-binding protein- brain-derived neurotrophic factor (CREB-BDNF) cascade has been linked to cognitive impairment in several studies. This study aimed to investigate the effect of minocycline on the levels of oxidative stress markers, CREB, and BDNF in lipopolysaccharide (LPS)-induced cognitive impairment. Fifty adult male Sprague Dawley rats were divided randomly into five groups. Group 1 was an untreated control group. Groups 2, 3, 4 and 5 were treated concurrently with LPS (5 mg/kg, i.p) once on day 5 and normal saline (0.7 ml/rat, i.p) or minocycline (25 and 50 mg/kg, i.p) or memantine (10 mg/kg, i.p) once daily from day 1 until day 14, respectively. From day 15 to day 22 of the experiment, Morris Water Maze (MWM) was used to evaluate learning and reference memory in rats. The levels of protein carbonyl (PCO), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD) were determined by enzyme-linked immunosorbent assay (ELISA). CREB and BDNF expression and density were measured by immunohistochemistry and western blot analysis, respectively. LPS administration significantly increased escape latency to the hidden platform with decreased travelled distance, swimming speed, target crossings and time spent in the target quadrant. Besides, the hippocampal tissue of LPS rats showed increased levels of PCO and MDA, decreased levels of CAT and SOD, and reduced expression and density of BDNF and CREB. Treatment with minocycline reversed these effects in a dose-dependent manner, comparable to the effects of memantine. Both doses of minocycline treatment protect against LPS-induced cognitive impairment by reducing oxidative stress and upregulating the CREB-BDNF signalling pathway in the rat hippocampus.
  15. 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.
  16. Doris M, Aziz F, Alhummiany H, Bawazeer T, Alsenany N, Mahmoud A, et al.
    Nanoscale Res Lett, 2017 Dec;12(1):67.
    PMID: 28116608 DOI: 10.1186/s11671-017-1851-0
    In this study, low-bandgap polymer poly{[4,4-bis(2-ethylhexyl)-cyclopenta-(2,1-b;3,4-b')dithiophen]-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl} (PCPDTBT) nanostructures have been synthesized via a hard nanoporous alumina template of centrifugal process. Centrifuge has been used to infiltrate the PCPDTBT solution into the nanoporous alumina by varying the rotational speeds. The rotational speed of centrifuge is directly proportional to the infiltration force that penetrates into the nanochannels of the template. By varying the rotational speed of centrifuge, different types of PCPDTBT nanostructures are procured. Infiltration force created during the centrifugal process has been found a dominant factor in tuning the morphological, optical, and structural properties of PCPDTBT nanostructures. The field emission scanning electron microscopy (FESEM) images proved the formation of nanotubes and nanowires. The energy-dispersive X-ray spectroscope (EDX) analysis showed that the nanostructures were composed of PCPDTBT with complete dissolution of the template.
  17. 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.
  18. Teridi MA, Sookhakian M, Basirun WJ, Zakaria R, Schneider FK, da Silva WJ, et al.
    Nanoscale, 2015 Apr 28;7(16):7091-100.
    PMID: 25640454 DOI: 10.1039/c4nr05874g
    High performance organic devices including polymer solar cells (PSCs) and light emitting diodes (PLEDs) were successfully demonstrated with the presence of highly ordered nanoimprinted Au nanodisks (Au NDs) in their solution-processed active/emissive layers, respectively. PSCs and PLEDs were fabricated using a low bandgap polymer and acceptor, nitrogen doped multiwalled carbon nanotubes poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophenediyl] (n-MWCNTs:PTB7), and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) and (4,4-N,N-dicarbazole) biphenyl (CBP) doped with tris(2-phenylpyridine) iridium(iii) (Ir(ppy)3) as active/emissive layers, respectively. We synthesized nitrogen doped graphene and used it as anodic buffer layer in both devices. The localized surface plasmon resonance (LSPR) effect from Au NDs clearly contributed to the increase in light absorption/emission in the active layers from electromagnetic field enhancement, which originated from the excited LSPR in PSCs and PLEDs. In addition to the high density of LSPR and strong exciton-SP coupling, the electroluminescent (EL) enhancement is ascribed to enhanced spontaneous emission rates. This is due to the plasmonic near-field effect induced by Au NDs. The PSCs and PLEDs exhibited 14.98% (8.08% to 9.29%) under one sun of simulated air mass 1.5 global (AM1.5G) illumination (100 mW cm(-2)) and 19.18% (8.24 to 9.82 lm W(-1)) enhancement in the power conversion efficiencies (PCEs) compared to the control devices without Au NDs.
  19. Shafin N, Ismail CAN, Mustafa MZ, Ghani N, Ahmad AH, Othman Z, et al.
    Mult Scler, 2022 Dec;28(14):2160-2170.
    PMID: 35164590 DOI: 10.1177/13524585221075542
    Recent interest in multiple sclerosis research warrants literature analysis to evaluate the current state of the discipline and new research domains. This bibliometric review summarised the research trends and analysed research areas in multiple sclerosis over the last decade. The documents containing the term 'multiple sclerosis' in the article title were retrieved from the Scopus database. We used Harzing's Publish or Perish and VOSviewer for citation analysis and data visualisation, respectively. We found a total of 18,003 articles published in journals in the English language between 2012 and 2021. The emerging keywords identified utilising the enhanced strategic diagram were 'covid-19', 'teriflunomide', 'clinical trial', 'microglia', 'b cells', 'myelin', 'brain', 'white matter', 'functional connectivity', 'pain', 'employment', 'health-related quality of life', 'meta-analysis' and 'comorbidity'. This study demonstrates the tremendous growth of multiple sclerosis literature worldwide, which is expected to grow more than double during the next decade especially in the identified emerging topics.
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links