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Mechanism of antagonistic effects of Andrographis paniculata methanolic extract against Staphylococcus aureus

Asian Pacific Journal of Tropical Medicine 2017年第7期10卷 747-757页

作者： Roslinah Mohamad Hussain Zayan Nabilah Rasyidah Abd.Razak wan mazlina md saad Maimunah Mustakim Department of Medical Laboratory Technology Faculty of Health SciencesUniversiti Teknologi MARA(UiTM)SelangorMalaysia

Objective: To investigate the effects of Andrographis paniculata(Burm.f.) Wall. Ex Nees(A. paniculata) on expressions and activities of catalase, superoxide dismutase and alkylhydroperoxide reductase C in Staphylococcus aureus(S. aureus) with respect to its survival in vitro. Methods: Antioxidative property of methanolic leaves extract of A. paniculata(0.06 mg/m L). Minimum inhibitory concentration(MIC) was determined by its ability to reduce hydrogen peroxide(H_2O_2) toxicity against S. aureus ATCC 25923(3.8×10~8 cfu/m L). Effects of the extract on expressions of kat A(encoding catalase), sod A and sod M [encoding superoxide dismutases(SODs)], and ahp C [encoding alkylhydroperoxide reductase C(AhpC)] in S. aureuswere determined by RT-q PCR and corresponding enzyme activity assays were performed. Nitroblue tetrazolium reduction(NBT) assay was performed to determine effects of the extract on intracellular and extracellular levels of O_2-in S. aureus. Results: Cells challenged with 7.5 mmol/L H_2O_2 showed 0% survival in 30 min whereas 25% survived after treatment with the extract and H_2O_2. Cells that were treated with the extract alone had 43% survival in the same exposure period. Expressions of sod A and sod M genes in extract-treated cells were lowered 0.8-fold and 0.7-fold, respectively with decrease in total SOD activity of 26.8 U compared to untreated cells, 32.4 U(P<0.05). In contrast, extract-treated S. aureus cells showed 3.3-fold increase in kat A expression with corresponding increase in catalase activity of 1.828 U compared to untreated cells which was 1.248 U,(P<0.05). More profoundly, ahp C expression was increased 61-fold in extract-treated cells,(P<0.05) with corresponding increase in Ahp C activity of 0.018 U compared to untreated cells, 0.012U,(P<0.05). Extract-treated cells had significantly lower intra-and extracellular O_2-levels with absorbance readings(A_(575nm)) of 0.340 and 0.524 compared to untreated cells which were 0.516 and 0.928(P<0.05)

关键词： Antagonistic effects Andrographis paniculata Oxidative stress resistance Staphylococcus aureus Superoxide dismutase Catalase

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Antibacterial mechanism with consequent cytotoxicity of different reinforcements in biodegradable magnesium and zinc alloys: A review

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Journal of Magnesium and Alloys 2023年第9期11卷 3038-3058页

作者： Chowdhury Ahmed Shahed Faiz Ahmad Ebru Günister Farhana Mohd Foudzi saad Ali Khurshid Malik wan Sharuzi wan Harun Department of Mechanical Engineering Universiti Teknologi PETRONAS(UTP)32610Seri IskandarPerakMalaysia Faculty of Engineering and Natural Sciences Department of Mechanical EngineeringIstanbul Health and Technology UniversityIstanbulTurkey Department of Mechanical and Manufacturing Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan Malaysia43600 UKM BangiSelangorMalaysia Faculty of Mechanical&Automotive Engineering Technology Universiti Malaysia Pahang26600 PekanPahangMalaysia

Benefits achieved by the biodegradable magnesium(Mg) and zinc(Zn) implants could be suppressed due to the invasion of infectious microbial, common bacteria, and fungi. Postoperative medications and the antibacterial properties of pure Mg and Zn are insufficient against biofilm and antibiotic-resistant bacteria, bringing osteomyelitis, necrosis, and even death. This study evaluates the antibacterial performance of biodegradable Mg and Zn alloys of different reinforcements, including silver(Ag), copper(Cu), lithium(Li), and gallium(Ga). Copper ions(Cu^(2+)) can eradicate biofilms and antibiotic-resistant bacteria by extracting electrons from the cellular structure. Silver ion(Ag^(+)) kills bacteria by creating bonds with the thiol group. Gallium ion(Ga^(3+)) inhibits ferric ion(Fe^(3+)) absorption, leading to nutrient deficiency and bacterial death. Nanoparticles and reactive oxygen species(ROS) can penetrate bacteria cell walls directly, develop bonds with receptors, and damage nucleotides. Antibacterial action depends on the alkali nature of metal ions and their degradation rate, which often causes cytotoxicity in living cells. Therefore, this review emphasizes the insight into degradation rate, antibacterial mechanism, and their consequent cytotoxicity and observes the correlation between antibacterial performance and oxidation number of metal ions.

关键词： Biodegradable materials Biomedical implants Antibacterial mechanism Cytotoxicity Reactive oxygen species

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Ternary phase behavior of water microemulsified diesel-palm biodiesel

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Frontiers in Energy 2015年第2期9卷 162-169页

作者： Nurul Atiqah Izzati md ISHAK lsmail Ab RAMAN Mohd Ambar YARMO wan Mohd Faizal wan MAHMOOD School of Chemical Sciences and Food Technology Faculty of Scienceand Technology Universiti Kebangsaan Malaysia UKM Bangi 43600Malaysia Advanced Oleochemical Technology Division (AOTD) MalaysianPalm Oil Board (MPOB) 6 Persiaran Institusi Bandar Baru BangiKajang 43000 Malaysia Department of Mechanical and Material Engineering Faculty ofEngineering and Built Environment Universiti Kebangsaan MalaysiaUKM Bangi 43600 Malaysia

This paper aims to develop a new microemul- sions system comprising diesel and palm oil methyl ester （PME） that have the potential to be used as alternative fuels for diesel engines. The water-in-diesel-biodiesel micro- emulsions were prepared by applying PME mixed with diesel, non-ionic surfactants, co-surfaetants and water to make the water-in-oil （W/O） microemulsion system. This microemulsified fuel was achieved through low-energy microemulsification by using the constant composition method. The diesel used was mixed with four different concentrations of PME, i.e., 10% （w/w）（B10）, 20% （w/w）（B20）, 30% （w/w）（B30） and neat diesel （B0）. The amount of water was fixed at 20% （w/w）. The phase behavior of the water/mixed non-ionic surfactant/diesel-PME system were studied by constructing pseudoternary phase diagrams with the goal of formulating optimized systems. The results showed that the microemulsions were formed and stabilized with a mixture of non-ionic surfactants at a weight ratio of 80：20 at 20% （w/w）, and with mixed co-surfactants at a weight ratio of 25：75, 20：80 and 10：90 for B0, B10, B20 and B30 respectively. The particle size, kinematic viscosity at 40℃, refractive index, density, heating value, cloud point, pour pointand flash point of the selected water-in-diesel microemulsion were 19.40 nm （polydispersity of 0.012）, 12.86mm^2/s, 1.435, 0.8913g/mL, 31.87MJ/kg, 7.15℃, 10.5℃ and 46.5℃ respectively. The corresponding values of the water-in-diesel@ME selected were 20.72nm to 23.74nm, 13.02mme/s to 13.29mmZ/s, 1.442, 0.8939g/mL to 0.8990g/mL, 31.45MJ/kg to 27.34 MJ/kg, 7.2℃ to 6.8℃, 8.5℃ to 1.5℃ and 47.5℃ to 52.0℃. These preliminary findings were further studied as potential fuels for diesel engines.

关键词： palm methyl ester palm oil biodiesel micro-emulsion water mieroemulsified fuels

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Susceptibility of Aedes albopictus from dengue outbreak areas to temephos and Bacillus thuringiensis ***

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Asian Pacific Journal of Tropical Biomedicine 2016年第4期6卷 295-300页

作者： Ahmad Mohiddin Asmalia md Lasim wan Fatma Zuharah School of Biological Science Universiti Sains Malaysia Centre of Chemical Biology Universiti Sains Malaysia Vector Control Research Unit School of Biological ScienceUniversiti Sains Malaysia

Objective:To monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected larvicides,temephos and Bacillus thuringiensis ***(Bti) which are commonly used by Penang Health Department for vector ***:The mosquito larvae were tested against two types of larvicides:(1) temephos(Abate®) with diagnostic dosage(0.012 mg/L) and operational dosage(1 mg/L) and(2)Bacillus thuringiensis ***(Vecto Bac®WG) with operational dosage ranging from 6 000 international toxic units per L to 24 000 international toxic unit per L.A total of 20 late third and early forth instar larvae were selected and transferred into paper cup sized 300 m L using wide-mouthed *** larvae were distributed into each 300 m L paper cup containing 50 m L of aged tap *** experiment was replicated five times for each concentration *** test was repeated three *** mortality was recorded after 24 h of exposure and recorded lethal time was based on 2 h for temephos and 6 h for *** control consisted of ethanol for temephos and only seasoned water for ***:The result showed that Aedes albopictus from Flat Hamna,Kampung Sungai Gelugor and Kampung Tanjung Tokong were still susceptible to Bti and ***,higher lethal time and resistance ratio were detected in strain from Flat Hamna which was a known dengue hot spot area in northeast of ***:The application of temephos and Bti in vector control activity in these selected localities is still relevant in the control of Aedes larvae populations.

关键词： Aedes albopictus Mosquito Larvicide Susceptibility

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Growth inhibitory response and ultrastructural modification of oral-associated candidal reference strains (ATCC) by Piper betle L. extract

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International Journal of Oral Science 2014年第1期6卷 15-21页

作者： Mohd-Al-Faisal Nordin wan Himratul-Aznita wan Harun Fathilah Abdul Razak md Yusoff Musa Department of Oral Biology and Biomedical Sciences Faculty of Dentistry University of Malaya Institute of Biological Sciences Faculty of ScienceUniversity of Malaya

Candida species have been associated with the emergence of strains resistant to selected antifungal agents. Plant products have been used traditionally as alternative medicine to ease mucosal fungal infections. This study aimed to investigate the effects of Piper betle extract on the growth profile and the ultrastructure of commonly isolated oral candidal cells. The major component of Po betle was identified using liquid chromatography-mass spectrophotometry （LC-MS/MS）. Seven ATCC control strains of Candida species were cultured in yeast peptone dextrose broth under four different growth environments：（i） in the absence of P. betle extract; and in the presence of P. beUeextract at respective concentrations of （ii） 1 ***-1; （iii） 3 ***-1; and （iv） 6 ***- 1 The growth inhibitory responses of the candidal cells were determined based on changes in the specific growth rates （μ）. Scanning electron microscopy （SEM） was used to observe any ultrastructural alterations in the candida colonies. LC-MS/MS was performed to validate the presence of bioactive compounds in the extract. Following treatment, it was observed that the p-values of the treated cells were significantly different than those of the untreated cells （P〈0.05）, indicating the fungistatic properties of the P. beUe extract. The candidal population was also reduced from an average of 13.44× 10^6 to 1.78×10^6 viable cell counts （CFU）.mL-1, SEM examination exhibited physical damage and considerable morphological alterations of the treated cells. The compound profile from LC-MS/MS indicated the presence of hydroxybenzoic acid, chavibetol and hydroxychavicol in P. betle extract. The effects of P. betle on candida cells could potentiate its antifungal activity.

关键词： antifungal activity Candida cell morphology growth inhibitory effect Piperbetle L.

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The Spatial Structure of Zooplankton Communities of Pedu Reservoir,Malaysia

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湿地科学 2012年第4期10卷 423-428页

作者： Amir Shah Ruddin md Shah Johan Ismail Diana Latief wan Maznah wan Omar School of Biological Sciences Universiti Sains MalaysiaMinden11800 PenangMalaysia Department of Animal Science and Fishery Faculty of Agriculture and Food SciencesUniversiti Putra MalaysiaUPM Bintulu Campus97008 BintuluSarawakMalaysia

A total of 22 species of zooplankton were identified from 8 sampling stations located in the limnetic zone of Pedu *** zooplankton community was dominated by rotifers (11 species),followed by cladocerans (9 species) and copepods (2 species).Four species of zooplankton comprised of 3 rotifers,Brachionus quadridentata,Brachionus caudatus and Keratella cochlearis and one cladoceran,Ceriodaphnia cornuta were present at all sampling *** richness was highest at Station 2 (17 species) followed by Station 4 and Station 8 (14 species),Station 5 (15 species),Station 7 (11 species),Station 6 (10 species),Station 3 (9 species) and Station 1 (7 species).With an exception of water transparency,all other water quality parameters such as temperature,dissolved oxygen,conductivity,pH and total dissolved solids were not significant when compared between sampling *** study found that station 5 which was located in a calm strait,protected from strong wave and wind was a suitable area for zooplankton growth and *** supporting the findings included highest water transparency (3.4 m),rich in species numbers (15 species),high diversity index (0.950) and evenness index (0.808).

关键词：水生生物学研究方法演化浮游生物

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Influence of biofilm-forming lactic acid bacteria against methicillin-resistan Staphylococcus aureus(MRSA S547)

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Asian Pacific Journal of Tropical Biomedicine 2017年第12期7卷 1107-1115页

作者： Laavanya M. Kumar wan Zuhainis saad Rosfarizan Mohamad Raha Abdul Rahim Department of Microbiology Faculty of Biotechnology and Biomolecular SciencesUniversity Putra Malaysia43400UPM SerdangSelangorMalaysia Department of Bioprocess Technology Faculty of Biotechnology and Biomolecular SciencesUniversity Putra Malaysia43400UPM SerdangSelangorMalaysia Department of Cell and Molecular Biology Faculty of Biotechnology and Biomolecular SciencesUniversity Putra Malaysia43400UPM SerdangSelangorMalaysia

Objective: To investigate the antibacterial effect of selected lactic acid bacteria(LAB)biofilms on the planktonic and biofilm population of methicillin-resistant Staphylococcus aureus(MRSA)(S547).Methods: In this study, biofilm-forming LAB were isolated from tairu and kefir. Isolate Y1 and isolate KF were selected based on their prominent inhibition against test pathogens(using spot-on-agar method and agar-well-diffusion assay) and efficient biofilm production(using tissue culture plate method). They were then identified as Lactobacillus casei(L. casei) Y1 and Lactobacillus plantarum(L. plantarum) KF, respectively using16 S r DNA gene sequencing. The influence of incubation time, temperature and aeration on the biofilm production of L. casei Y1 and L. plantarum KF was also investigated using tissue culture plate method. The inhibitory activity of both the selected LAB biofilms was evaluated against MRSA(Institute for Medical Research code: S547) using L. plantarum ATCC 8014 as the reference ***: L. casei Y1 showed the highest reduction of MRSA biofilms, by 3.53 log at48 h while L. plantarum KF records the highest reduction of 2.64 log at 36 h. In inhibiting planktonic population of MRSA(S547), both L. casei Y1 and L. plantarum KF biofilms recorded their maximum reduction of 4.13 log and 3.41 log at 24 h, respectively. Despite their inhibitory effects being time-dependent, both LAB biofilms exhibited good potential in controlling the biofilm and planktonic population of MRSA(S547).Conclusions: The results from this study could highlight the importance of analysing biofilms of LAB to enhance their antibacterial efficacy. Preferably, these protective biofilms of LAB could also be a better alternative to control the formation of biofilms by pathogens such as MRSA.

关键词： MRSA Biofilms Lactic acid bacteria Antibacterial

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Comparison of catalyst-coated membranes and catalyst-coated substrate for PEMFC membrane electrode assembly:A review

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Chinese Journal of Chemical Engineering 2021年第5期34卷 1-16页

作者： Bee Huah Lim Edy Herianto Majlan Ahmad Tajuddin Teuku Husaini wan Ramli wan Daud Nabilah Afiqah Mohd Radzuan md.Ahsanul Haque Fuel Cell Institute Universiti Kebangsaan MalaysiaUKM Bangi 43600Selangor Darul EhsanMalaysia Faculty of Engineering and Built Environment Mahsa UniversityJenjarom 42610Selangor Darul EhsanMalaysia Research Centre for Sustainable Process Technology(CESPRO) Universiti Kebangsaan MalaysiaUKM Bangi 43600Selangor Darul EhsanMalaysia Department of Applied Chemistry&Chemical Engineering Islamic UniversityKushtia 7003Bangladesh

Catalyst-coated membranes(CCMs)have gained popularity among membrane electrode assembly(MEA)fabricators for their abilities and advantages compared with those of other methods,such as catalyst-coated substrates(CCSs).CCMs show a profound new analysis for reducing platinum(Pt)catalyst *** addition,they increase the total number of reactions that occur on the MEA because of their active area amplification,which leads to an improved catalyst-utilization efficiency ***,several characteristics are involved in the MEA fabrication ***-manufacturing effects with regard to catalyst inks and analysis of the overall performance of MEAs prepared by the CCM and CCS methods are *** deliberation emphasizes the practical approaches in minimizing performance deterioration during the fabrication of MEAs using the CCM method and converses the commercialization of the CCM fabrication method toward developing an end *** research is required for MEA fabrication using the CCM methods to ensure that the fuel cell performance is ***,this review is focusing on the pros and cons of both distinguished methods,that is,CCM and CCS fabrication,for better comparison.

关键词： Catalyst-coated substrate Catalyst-coated membrane Direct spraying Doctor blade coating Decal transfer

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Controllable Macroscopic Architecture of Subtractive Manufactured Porous Iron for Cancellous Bone Analogue:Computational to Experimental Validation

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Journal of Bionic Engineering 2020年第2期17卷 357-369页

作者： Muhammad Azfar Noordin Rabiatul Adibah Abdul Rahim Ahmad Nabeel Hakimi Roslan Iza Azura Ali Ardiyansyah Syahrom Amir Putra md saad Applied Mechanics and Design School of Mechanical EngineeringFaculty of EngineeringUniversiti Teknologi Malaysia81310 UTM Johor BahruMalaysia Medical Devices and Technology Centre(MEDiTEC) Institute of Human Centred and Engineering(iHumEn)Universiti Teknologi Malaysia81310 UTM Johor BahruMalaysia School of Biomedical&Health Science Faculty of EngineeringUniversiti Teknologi Malaysia81310 UTM Johor BahruMalaysia

Higher strength and lower degradation rate of Fe compared to magnesium and zinc have made it the most reliable for orthopaedic ***,this paper studies the morphological and mechanical characteristics of porous Fe fabricated using subtractive manufacturing for load bearing bone *** types of porous Fe(19%,39%and 59%)were prepared and then modelled into a 3D model for finite element *** mechanical properties evaluated through finite element analysis were then validated by the experimental *** fluid dynamics was done in this study to evaluate the permeability and wall shear stress of the porous *** between morphological indices,mechanical properties,shear stress and permeability were then *** mechanical behaviour of porous Fe investigated through finite element analysis was in good agreement with the experimental *** mechanical properties of porous Fe specimen particularly sample C(modulus:5.63 GPa and yield strength:145.7 MPa)was tailored to the cancellous bone(modulus:0.5 GPa-18 GPa and yield strength:101 MPa-169.6 MPa).As the porosity increased,the performance of porous Fe regarding mechanical properties and morphological properties were enhanced.

关键词： mechanical characterization morphology finite element analysis porous iron shear stress permeability

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Central retinal artery occlusion and optic neuropathy secondary to platelet rich plasma injection:a case report

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International Journal of Ophthalmology(English edition) 2021年第6期14卷 945-947页

作者： Norashikin Maslan wan Haslina wan Abdul Halim Norshamsiah md Din Seng Fai Tang Department of Ophthalmology Universiti Kebangsaan Malaysia Medical Centre(UKMMC)Cheras 56000Kuala LumpurMalaysia

Dear Editor.I am *** Maslan,from the Department of Ophthalmology of University Kebangsaan Malaysia Medical Centre in Kuala Lumpur,Malaysia.I am writing to present a case report on central retina artery occlusion(CRAO)... 详细信息

关键词： injection Malaysia neuropathy

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