Browse publications by year: 2012

  1. Cardamonin from Alpinia rafflesiana inhibits inflammatory responses in IFN-γ/LPS-stimulated BV2 microglia via NF-κB signalling pathway
    Chow YL, Lee KH, Vidyadaran S, Lajis NH, Akhtar MN, Israf DA, et al.
    Int Immunopharmacol, 2012 Apr;12(4):657-65.
    PMID: 22306767 DOI: 10.1016/j.intimp.2012.01.009
    The increasing prevalence of neurodegenerative diseases has prompted investigation into innovative therapeutics over the last two decades. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the therapeutic choices to control and suppress the symptoms of neurodegenerative diseases. However, NSAIDs-associated gastropathy has hampered their long term usage despite their clinical advancement. On the natural end of the treatment spectrum, our group has shown that cardamonin (2',4'-dihydroxy-6'-methoxychalcone) isolated from Alpinia rafflesiana exerts potential anti-inflammatory activity in activated macrophages. Therefore, we further explored the anti-inflammatory property of cardamonin as well as its underlying mechanism of action in IFN-γ/LPS-stimulated microglial cells. In this investigation, cardamonin shows promising anti-inflammatory activity in microglial cell line BV2 by inhibiting the secretion of pro-inflammatory mediators including nitric oxide (NO), prostaglandin E(2) (PGE(2)), tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). The inhibition of NO and PGE(2) by cardamonin are resulted from the reduced expression of inducible nitric oxide synthase (iNOS) and cycloxygenase-2 (COX-2), respectively. Meanwhile the suppressive effects of cardamonin on TNF-α, IL-1β and IL-6 were demonstrated at both protein and mRNA levels, thus indicating the interference of upstream signal transduction pathway. Our results also validate that cardamonin interrupts nuclear factor-kappa B (NF-κB) signalling pathway via attenuation of NF-κB DNA binding activity. Interestingly, cardamonin also showed a consistent suppressive effect on the cell surface expression of CD14. Taken together, our experimental data provide mechanistic insights for the anti-inflammatory actions of cardamonin in BV2 and thus suggest a possible therapeutic application of cardamonin for targeting neuroinflammatory disorders.
    MeSH terms: Animals; Anti-Inflammatory Agents/pharmacology*; Cell Line; DNA/immunology; Interferon-gamma/pharmacology; Lipopolysaccharides/pharmacology; Nitric Oxide/immunology; Nitrites/immunology; Dinoprostone/immunology; Gene Expression/drug effects; Cytokines/genetics; NF-kappa B/immunology*; Microglia/drug effects*; Microglia/immunology; Antigens, CD14/immunology; Alpinia*; Chalcones/pharmacology*; Mice; Cyclooxygenase 2/immunology; Nitric Oxide Synthase Type II/immunology
  2. In vitro modulatory effects of flavonoids on human cytochrome P450 2C8 (CYP2C8)
    Pang CY, Mak JW, Ismail R, Ong CE
    Naunyn Schmiedebergs Arch Pharmacol, 2012 May;385(5):495-502.
    PMID: 22307090 DOI: 10.1007/s00210-012-0731-5
    The inhibitory effects of five flavonoids with distinct chemical classes (flavones [luteolin], flavonols [quercetin and quercitrin], and flavanones [hesperetin and hespiridin]) on cDNA-expressed CYP2C8 were investigated. CYP2C8 was co-expressed with NADPH-cytochrome P450 reductase in Escherichia coli and used to characterise potency and mechanism of these flavonoids on the isoform. Tolbutamide 4-methylhydroxylase, a high-performance liquid chromatography-based assay, was selected as marker activity for CYP2C8. Our results indicated that the flavonoids inhibited CYP2C8 with different potency. The order of inhibitory activities was quercetin > luteolin > hesperetin > hesperidin > quercitrin. All of these compounds however exhibited mechanism-based inhibition. A number of structural factors were found to be important for inhibition; these include the molecular shape (volume to surface ratio), the number of hydroxyl groups as well as glycosylation of the hydroxyl group. Quercetin was the most potent inhibitor among the flavonoids examined in this study, and our data suggest that it should be examined for potential pharmacokinetic drug interactions pertaining to CYP2C8 substrates in vivo.
    MeSH terms: Aryl Hydrocarbon Hydroxylases/antagonists & inhibitors; Aryl Hydrocarbon Hydroxylases/genetics; Aryl Hydrocarbon Hydroxylases/metabolism*; Enzyme Inhibitors/pharmacology*; Enzyme Inhibitors/chemistry; Escherichia coli/genetics; Flavonoids/pharmacology*; Flavonoids/chemistry; Humans; NADPH-Ferrihemoprotein Reductase/genetics; Structure-Activity Relationship; Cytochrome P-450 CYP2C8
  3. Analysis of the genetic diversity of physic nut, Jatropha curcas L. accessions using RAPD markers
    Rafii MY, Shabanimofrad M, Puteri Edaroyati MW, Latif MA
    Mol Biol Rep, 2012 Jun;39(6):6505-11.
    PMID: 22307785 DOI: 10.1007/s11033-012-1478-2
    A sum of 48 accessions of physic nut, Jatropha curcas L. were analyzed to determine the genetic diversity and association between geographical origin using RAPD-PCR markers. Eight primers generated a total of 92 fragments with an average of 11.5 amplicons per primer. Polymorphism percentages of J. curcas accessions for Selangor, Kelantan, and Terengganu states were 80.4, 50.0, and 58.7%, respectively, with an average of 63.04%. Jaccard's genetic similarity co-efficient indicated the high level of genetic variation among the accessions which ranged between 0.06 and 0.81. According to UPGMA dendrogram, 48 J. curcas accessions were grouped into four major clusters at coefficient level 0.3 and accessions from same and near states or regions were found to be grouped together according to their geographical origin. Coefficient of genetic differentiation (G(st)) value of J. curcas revealed that it is an outcrossing species.
    MeSH terms: Genetic Markers; Malaysia; Models, Genetic; Phylogeny; Genetic Variation*; Cluster Analysis; Random Amplified Polymorphic DNA Technique; Principal Component Analysis; Jatropha/genetics*
  4. Effects of diarylpentanoid analogues of curcumin on chemiluminescence and chemotactic activities of phagocytes
    Jantan I, Bukhari SN, Lajis NH, Abas F, Wai LK, Jasamai M
    J Pharm Pharmacol, 2012 Mar;64(3):404-12.
    PMID: 22309272 DOI: 10.1111/j.2042-7158.2011.01423.x
    A series of 43 curcumin diarylpentanoid analogues were synthesized and evaluated for their inhibitory effects on the chemiluminescence and chemotactic activity of phagocytes in vitro.
    MeSH terms: Anti-Inflammatory Agents/pharmacology*; Chemotaxis/drug effects*; Curcumin/analogs & derivatives; Curcumin/pharmacology*; Humans; Luminescent Measurements/methods; Neutrophils/drug effects*; Phagocytes/drug effects*; Respiratory Burst/drug effects*; Reactive Oxygen Species/pharmacology; Luminescence
  5. Fulltext Basic fibroblast growth factor modulates cell cycle of human umbilical cord-derived mesenchymal stem cells
    Ramasamy R, Tong CK, Yip WK, Vellasamy S, Tan BC, Seow HF
    Cell Prolif, 2012 Apr;45(2):132-9.
    PMID: 22309282 DOI: 10.1111/j.1365-2184.2012.00808.x
    BACKGROUND: Mesenchymal stem cells (MSC) have great potential in regenerative medicine, immunotherapy and gene therapy due to their unique properties of self-renewal, high plasticity, immune modulation and ease for genetic modification. However, production of MSC at sufficient clinical scale remains an issue as in vitro generation of MSC inadequately fulfils the demand with respect to patients.

    OBJECTIVES: This study has aimed to establish optimum conditions to generate and characterize MSC from human umbilical cord (UC-MSC).

    MATERIALS AND METHODS: To optimize MSC population growth, basic fibroblast growth factor (bFGF) was utilized in culture media. Effects of bFGF on expansion kinetics, cell cycle, survival of UC-MSC, cytokine secretion, expression of early stem-cell markers and immunomodulation were investigated.

    RESULTS: bFGF supplementation profoundly enhanced UC-MSC proliferation by reducing population doubling time without altering immunophenotype and immunomodulatory function of UC-MSC. However, cell cycle studies revealed that bFGF drove the cells into the cell cycle, as a higher proportion of cells resided in S phase and progressed into M phase. Consistent with this, bFGF was shown to promote expression of cyclin D proteins and their relevant kinases to drive UC-MSC to transverse cell cycle check points, thus, committing the cells to DNA synthesis. Furthermore, supplementation with bFGF changed the cytokine profiles of the cells and reduced their apoptotic level.

    CONCLUSION: Our study showed that bFGF supplementation of UC-MSC culture enhanced the cells' growth kinetics without compromising their nature.

    MeSH terms: Cell Communication/immunology; Cell Cycle/drug effects; Cell Differentiation/drug effects; Female; Humans; Pregnancy; T-Lymphocytes/immunology; Umbilical Cord/cytology*; Cytokines/biosynthesis; Fibroblast Growth Factor 2/administration & dosage; Fibroblast Growth Factor 2/pharmacology*; Apoptosis/drug effects; Cell Cycle Proteins/biosynthesis; Cell Culture Techniques; Matrix Metalloproteinase 3/metabolism; Vascular Endothelial Growth Factor A/metabolism; Cell Proliferation/drug effects; Mesenchymal Stromal Cells/cytology*; Mesenchymal Stromal Cells/drug effects*; Mesenchymal Stromal Cells/immunology; Mesenchymal Stromal Cells/metabolism
  6. Methotrexate toxicity presenting as ulcerated psoriatic plaques
    Wong SM, Chong YT, Thevarajah S, Baba R
    Australas J Dermatol, 2012 Feb;53(1):81-3.
    PMID: 22309341 DOI: 10.1111/j.1440-0960.2011.00779.x
    Methotrexate toxicity is known to cause erosions of existing psoriatic plaques, although rare. We describe two patients who developed painful ulcerated psoriatic plaques as an early presenting sign of methotrexate toxicity and review the risk factors associated with this manifestation.
    MeSH terms: Dermatologic Agents/adverse effects*; Female; Humans; Male; Methotrexate/adverse effects*; Middle Aged; Psoriasis/chemically induced*; Psoriasis/diagnosis; Risk Factors; Skin Ulcer/chemically induced*; Skin Ulcer/diagnosis; Torso
  7. Sustained-release alginate-chitosan pellets prepared by melt pelletization technique
    Wong TW, Nurulaini H
    Drug Dev Ind Pharm, 2012 Dec;38(12):1417-27.
    PMID: 22309449 DOI: 10.3109/03639045.2011.653364
    Alginate-chitosan pellets prepared by extrusion-spheronization technique exhibited fast drug dissolution.
    MeSH terms: Acetates/chemistry; Alginates/chemistry*; Biocompatible Materials/chemistry*; Drug Carriers/chemistry*; Drug Compounding/methods*; Drug Implants/chemistry; Solubility; Spectroscopy, Fourier Transform Infrared; Calcium Compounds/chemistry; Chitosan/chemistry*
  8. Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay
    Adzmi F, Meon S, Musa MH, Yusuf NA
    J Microencapsul, 2012;29(3):205-10.
    PMID: 22309479 DOI: 10.3109/02652048.2012.659286
    Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p 
    MeSH terms: Alginates/chemistry*; Aluminum Silicates; Bentonite/chemistry*; Calcium/chemistry; Drug Compounding*; Hexuronic Acids/chemistry; Materials Testing; Microscopy, Electron, Scanning/methods; Particle Size; Polymers/chemistry; Temperature; Thermogravimetry/methods; Trichoderma/metabolism*; Porosity; Spectroscopy, Fourier Transform Infrared/methods; Glucuronic Acid/chemistry
  9. Swelling behaviour and controlled drug release from cross-linked κ-carrageenan/NaCMC hydrogel by diffusion mechanism
    Hezaveh H, Muhamad II, Noshadi I, Shu Fen L, Ngadi N
    J Microencapsul, 2012;29(4):368-79.
    PMID: 22309480 DOI: 10.3109/02652048.2011.651501
    We studied a model system of controlled drug release using beta-carotene and κ-carrageenan/NaCMC hydrogel as a drug and a device, respectively. Different concentrations of genipin were added to crosslink the beta-carotene loaded beads by using the dripping method. Results have shown that the cross-linked beads possess lower swelling ability in all pH conditions (pH 1.2 and 7.4), and swelling ratio decreases with increasing genipin concentration. Microstructure study shows that cross-linking has enhanced the stability and structure of the beads network. Determination of diffusion coefficient for the release of encapsulated beta-carotene indicates less diffusivity when beads are cross-linked. Swelling models using adaptive neuro fuzzy show that using genipin as a cross-linker in the kC/NaCMC hydrogels affects the transport mechanism. The model shows very good agreement with the experimental data that indicates that applying ANFIS modelling is an accurate, rapid and simple way to model in such a case for controlled release applications.
    MeSH terms: Carboxymethylcellulose Sodium/chemistry; Carrageenan/chemistry; Cross-Linking Reagents; Diffusion; Drug Carriers/chemistry*; Drug Compounding/methods*; Microscopy, Electron, Scanning; Drug Delivery Systems*; Neural Networks (Computer); Fuzzy Logic; beta Carotene/administration & dosage; Hydrogels; Iridoids
  10. Effects of Bluetooth device electromagnetic field on hearing: pilot study
    Balachandran R, Prepageran N, Prepagaran N, Rahmat O, Zulkiflee AB, Hufaida KS
    J Laryngol Otol, 2012 Apr;126(4):345-8.
    PMID: 22310164 DOI: 10.1017/S0022215112000047
    The Bluetooth wireless headset has been promoted as a 'hands-free' device with a low emission of electromagnetic radiation.
    MeSH terms: Adult; Audiometry, Pure-Tone; Auditory Threshold/radiation effects; Cochlea; Electromagnetic Fields/adverse effects*; Female; Hearing/radiation effects*; Humans; Male; Pilot Projects; Prospective Studies; Otoacoustic Emissions, Spontaneous/physiology; Hearing Loss; Cell Phones*; Young Adult; Wireless Technology*
  11. Soil-transmitted helminthiasis: a critical but neglected factor influencing school participation of Aboriginal children in rural Malaysia
    Ahmed A, Al-Mekhlafi HM, Azam MN, Ithoi I, Al-Adhroey AH, Abdulsalam AM, et al.
    Parasitology, 2012 May;139(6):802-8.
    PMID: 22310239 DOI: 10.1017/S003118201100237X
    Soil-transmitted helminthiasis (STH), among the most common neglected tropical diseases, is a major public health problem in Malaysia with a possible impact on the nutritional status and school participation of rural children. This study was carried out among Aboriginal schoolchildren, living in an endemic area for STH in Malaysia, to determine the possible relationship between intestinal helminthiasis and school absenteeism. We also evaluated whether successful treatment of the infection will affect school attendance among the subjects. Stool analysis revealed that more than 90% of the subjects were infected with at least 1 helminth species, with Ascaris lumbricoides and Trichuris trichiura infections being most prevalent. Infection of moderate-to-heavy worm burdens, low level of fathers' education and anaemia were identified as the significant predictors of high absenteeism among the subjects (P<0·05). Following treatment of the infected children, it was found that school absenteeism was reduced significantly (P<0·01). In conclusion, STH continues to have significant impacts on public health, particularly in rural communities with a negatively significant effect on the school participation of Aboriginal children. A school-based de-worming programme should be introduced and incorporated in the current educational assistance targeted towards the Aboriginal communities, under the auspices of the government.
    MeSH terms: Absenteeism*; Adolescent; Animals; Ascariasis/epidemiology; Ascariasis/parasitology; Ascariasis/prevention & control; Ascariasis/transmission; Child; Feces/parasitology; Female; Helminthiasis/epidemiology*; Helminthiasis/parasitology; Helminthiasis/prevention & control; Helminthiasis/transmission; Helminths; Hookworm Infections/epidemiology; Hookworm Infections/parasitology; Hookworm Infections/prevention & control; Hookworm Infections/transmission; Humans; Intestinal Diseases/epidemiology*; Intestinal Diseases/parasitology; Intestinal Diseases/prevention & control; Intestinal Diseases, Parasitic; Malaysia/epidemiology; Male; Nutritional Status; Recurrence; Rural Population*; Schools*; Soil/parasitology*; Students*; Trichuriasis/epidemiology; Trichuriasis/parasitology; Trichuriasis/prevention & control; Trichuriasis/transmission
  12. The place of health and the health of place: dengue fever and urban governance in Putrajaya, Malaysia
    Mulligan K, Elliott SJ, Schuster-Wallace C
    Health Place, 2012 May;18(3):613-20.
    PMID: 22310527 DOI: 10.1016/j.healthplace.2012.01.001
    This case study investigates the connections among urban planning, governance and dengue fever in an emerging market context in the Global South. Key informant interviews were conducted with leading figures in public health, urban planning and governance in the planned city of Putrajaya, Malaysia. Drawing on theories of urban political ecology and ecosocial epidemiology, the qualitative study found the health of place - expressed as dengue-bearing mosquitoes and dengue fever in human bodies in the urban environment - was influenced by the place of health in a hierarchy of urban priorities.
    MeSH terms: City Planning/organization & administration; Dengue/epidemiology*; Humans; Interviews as Topic; Malaysia/epidemiology; Politics; Public Health; Urban Health*; Models, Organizational
  13. Fulltext Photocatalytic degradation of p-cresol by zinc oxide under UV irradiation
    Abdollahi Y, Abdullah AH, Zainal Z, Yusof NA
    Int J Mol Sci, 2012;13(1):302-15.
    PMID: 22312253 DOI: 10.3390/ijms13010302
    Photocatalytic degradation of p-cresol was carried out using ZnO under UV irradiation. The amount of photocatalyst, concentration of p-cresol and pH were studied as variables. The residual concentration and mineralization of p-cresol was monitored using a UV-visible spectrophotometer and total organic carbon (TOC) analyzer, respectively. The intermediates were detected by ultra high pressure liquid chromatography (UPLC). The highest photodegradation of p-cresol was observed at 2.5 g/L of ZnO and 100 ppm of p-cresol. P-cresol photocatalytic degradation was favorable in the pH range of 6-9. The detected intermediates were 4-hydroxy-benzaldehyde and 4-methyl-1,2-benzodiol. TOC studies show that 93% of total organic carbon was removed from solution during irradiation time. Reusability shows no significant reduction in photocatalytic performance in photodegrading p-cresol.
    MeSH terms: Catalysis; Chromatography, High Pressure Liquid; Cresols/metabolism; Cresols/chemistry*; Hydrogen-Ion Concentration; Kinetics; Photolysis/radiation effects; Ultraviolet Rays*; Water Pollutants, Chemical/metabolism; Water Pollutants, Chemical/chemistry*; Zinc Oxide/chemistry*
  14. Fulltext Wound healing activity of Elaeis guineensis leaf extract ointment
    Sasidharan S, Logeswaran S, Latha LY
    Int J Mol Sci, 2012;13(1):336-47.
    PMID: 22312255 DOI: 10.3390/ijms13010336
    Elaeis guineensis of the Arecaceae family is widely used in the traditional medicine of societies in West Africa for treating various ailments. To validate the ethnotherapeutic claims of the plant in skin diseases, wound healing activity was studied. The results showed that E. guineensis leaf extract had potent wound healing capacity as evident from the better wound closure (P < 0.05), improved tissue regeneration at the wound site, and supporting histopathological parameters pertaining to wound healing. Matrix metalloproteinases expression correlated well with the results thus confirming efficacy of E. guineensis in the treatment of the wound. E. guineensis accelerated wound healing in rats, thus supporting its traditional use. The result of this study suggested that, used efficiently, oil palm leaf extract is a renewable resource with wound healing properties.
    MeSH terms: Animals; Ointments/pharmacology*; Ointments/chemistry; Plant Extracts/pharmacology*; Plant Extracts/chemistry; Skin/enzymology; Skin/pathology; Wound Healing/drug effects*; Rats, Sprague-Dawley; Plant Leaves/metabolism; Plant Leaves/chemistry; Matrix Metalloproteinases/metabolism; Arecaceae/metabolism; Arecaceae/chemistry*; Rats
  15. Fulltext Involvement of nitrogen on flavonoids, glutathione, anthocyanin, ascorbic acid and antioxidant activities of Malaysian medicinal plant Labisia pumila Blume (Kacip Fatimah)
    Ibrahim MH, Jaafar HZ, Rahmat A, Rahman ZA
    Int J Mol Sci, 2012;13(1):393-408.
    PMID: 22312260 DOI: 10.3390/ijms13010393
    A split plot 3 by 4 experiment was designed to characterize the relationship between production of gluthatione (GSH), oxidized gluthatione (GSSG), total flavonoid, anthocyanin, ascorbic acid and antioxidant activities (FRAP and DPPH) in three varieties of Labisia pumila Blume, namely the varieties alata, pumila and lanceolata, under four levels of nitrogen fertilization (0, 90, 180 and 270 kg N/ha) for 15 weeks. The treatment effects were solely contributed by nitrogen application; there was neither varietal nor interaction effects observed. As the nitrogen levels decreased from 270 to 0 kg N/ha, the production of GSH and GSSG, anthocyanin, total flavonoid and ascorbic acid increased steadily. At the highest nitrogen treatment level, L. pumila exhibited significantly lower antioxidant activities (DPPH and FRAP) than those exposed to limited nitrogen growing conditions. Significant positive correlation was obtained between antioxidant activities (DPPH and FRAP), total flavonoid, GSH, GSSG, anthocyanin and ascorbic acid suggesting that an increase in the antioxidative activities in L. pumila under low nitrogen fertilization could be attributed to higher contents of these compounds. From this observation, it could be concluded that in order to avoid negative effects on the quality of L. pumila, it is advisable to avoid excessive application of nitrogen fertilizer when cultivating the herb for its medicinal use.
    MeSH terms: Anthocyanins/analysis; Anthocyanins/chemistry*; Antioxidants/metabolism; Antioxidants/chemistry*; Ascorbic Acid/analysis; Ascorbic Acid/chemistry*; Fertilizers; Flavonoids/analysis; Flavonoids/chemistry*; Glutathione/analysis; Glutathione/chemistry*; Malaysia; Nitrogen/metabolism*; Plant Extracts/chemistry; Plants, Medicinal/metabolism; Plants, Medicinal/chemistry; Spectrophotometry; Plant Leaves/metabolism; Plant Leaves/chemistry; Plant Roots/metabolism; Plant Roots/chemistry; Plant Stems/metabolism; Plant Stems/chemistry; Primulaceae/metabolism; Primulaceae/chemistry*
  16. Fulltext Structural modeling and biochemical characterization of recombinant KPN_02809, a zinc-dependent metalloprotease from Klebsiella pneumoniae MGH 78578
    Wong MT, Choi SB, Kuan CS, Chua SL, Chang CH, Normi YM, et al.
    Int J Mol Sci, 2012;13(1):901-17.
    PMID: 22312293 DOI: 10.3390/ijms13010901
    Klebsiella pneumoniae is a Gram-negative, cylindrical rod shaped opportunistic pathogen that is found in the environment as well as existing as a normal flora in mammalian mucosal surfaces such as the mouth, skin, and intestines. Clinically it is the most important member of the family of Enterobacteriaceae that causes neonatal sepsis and nosocomial infections. In this work, a combination of protein sequence analysis, structural modeling and molecular docking simulation approaches were employed to provide an understanding of the possible functions and characteristics of a hypothetical protein (KPN_02809) from K. pneumoniae MGH 78578. The computational analyses showed that this protein was a metalloprotease with zinc binding motif, HEXXH. To verify this result, a ypfJ gene which encodes for this hypothetical protein was cloned from K. pneumoniae MGH 78578 and the protein was overexpressed in Escherichia coli BL21 (DE3). The purified protein was about 32 kDa and showed maximum protease activity at 30 °C and pH 8.0. The enzyme activity was inhibited by metalloprotease inhibitors such as EDTA, 1,10-phenanthroline and reducing agent, 1,4-dithiothreitol (DTT). Each molecule of KPN_02809 protein was also shown to bind one zinc ion. Hence, for the first time, we experimentally confirmed that KPN_02809 is an active enzyme with zinc metalloprotease activity.
    MeSH terms: Amino Acid Sequence; Binding Sites; Cloning, Molecular; Escherichia coli/metabolism; Hydrogen-Ion Concentration; Klebsiella pneumoniae/enzymology*; Molecular Sequence Data; Phenanthrolines/metabolism; Phenanthrolines/chemistry; Recombinant Proteins/biosynthesis; Recombinant Proteins/genetics; Recombinant Proteins/chemistry; Temperature; Zinc/chemistry; Sequence Alignment; Protein Structure, Tertiary; Metalloproteases/genetics; Metalloproteases/metabolism*; Metalloproteases/chemistry; Molecular Docking Simulation
  17. Fulltext Characterization of electrosynthesized conjugated polymer-carbon nanotube composite: optical nonlinearity and electrical property
    Bahrami A, Talib ZA, Shahriari E, Yunus WMM, Kasim A, Behzad K
    Int J Mol Sci, 2012;13(1):918-928.
    PMID: 22312294 DOI: 10.3390/ijms13010918
    The effects of multi-walled carbon nanotube (MWNT) concentration on the structural, optical and electrical properties of conjugated polymer-carbon nanotube composite are discussed. Multi-walled carbon nanotube-polypyrrole nanocomposites were synthesized by electrochemical polymerization of monomers in the presence of different amounts of MWNTs using sodium dodecylbenzensulfonate (SDBS) as surfactant at room temperature and normal pressure. Field emission scanning electron microscopy (FESEM) indicates that the polymer is wrapped around the nanotubes. Measurement of the nonlinear refractive indices (n(2)) and the nonlinear absorption (β) of the samples with different MWNT concentrations measurements were performed by a single Z-scan method using continuous wave (CW) laser beam excitation wavelength of λ = 532 nm. The results show that both nonlinear optical parameters increased with increasing the concentration of MWNTs. The third order nonlinear susceptibilities were also calculated and found to follow the same trend as n(2) and β. In addition, the conductivity of the composite film was found to increase rapidly with the increase in the MWNT concentration.
    MeSH terms: Benzenesulfonates/chemistry; Electric Conductivity; Microscopy, Electron, Scanning; Polymers/chemistry*; Pressure; Pyrroles/chemistry; Spectrophotometry, Ultraviolet; Temperature; Nanotubes, Carbon/chemistry*
  18. Fulltext Improvement of thermal stability via outer-loop ion pair interaction of mutated T1 lipase from Geobacillus zalihae strain T1
    Ruslan R, Abd Rahman RN, Leow TC, Ali MS, Basri M, Salleh AB
    Int J Mol Sci, 2012;13(1):943-60.
    PMID: 22312296 DOI: 10.3390/ijms13010943
    Mutant D311E and K344R were constructed using site-directed mutagenesis to introduce an additional ion pair at the inter-loop and the intra-loop, respectively, to determine the effect of ion pairs on the stability of T1 lipase isolated from Geobacillus zalihae. A series of purification steps was applied, and the pure lipases of T1, D311E and K344R were obtained. The wild-type and mutant lipases were analyzed using circular dichroism. The T(m) for T1 lipase, D311E lipase and K344R lipase were approximately 68.52 °C, 70.59 °C and 68.54 °C, respectively. Mutation at D311 increases the stability of T1 lipase and exhibited higher T(m) as compared to the wild-type and K344R. Based on the above, D311E lipase was chosen for further study. D311E lipase was successfully crystallized using the sitting drop vapor diffusion method. The crystal was diffracted at 2.1 Å using an in-house X-ray beam and belonged to the monoclinic space group C2 with the unit cell parameters a = 117.32 Å, b = 81.16 Å and c = 100.14 Å. Structural analysis showed the existence of an additional ion pair around E311 in the structure of D311E. The additional ion pair in D311E may regulate the stability of this mutant lipase at high temperatures as predicted in silico and spectroscopically.
    MeSH terms: Bacterial Proteins/genetics; Bacterial Proteins/metabolism*; Bacterial Proteins/chemistry; Circular Dichroism; Enzyme Stability; Hydrogen Bonding; Ions/chemistry; Lipase/genetics; Lipase/metabolism*; Lipase/chemistry; Recombinant Proteins/biosynthesis; Recombinant Proteins/genetics; Recombinant Proteins/chemistry; Temperature; Mutagenesis, Site-Directed; Protein Structure, Tertiary; Crystallography, X-Ray; Transition Temperature; Geobacillus/enzymology*
  19. Fulltext Prebiotic activity of polysaccharides extracted from Gigantochloa levis (Buluh beting) shoots
    Azmi AF, Mustafa S, Hashim DM, Manap YA
    Molecules, 2012 Feb 07;17(2):1635-51.
    PMID: 22314383 DOI: 10.3390/molecules17021635
    Bamboo shoot crude polysaccharides (BSCP) extracted from the shoots of Gigantochloa levis gave about 3.27 ± 0.18% on dry basis and a very minute percentage of protein (0.02 ± 0.01%). The molecular weight of BSCP estimated by gel chromatography was found to be around 7.49 × 103 Da, while the molecular weights of purified fractions (F1 to F5) were around 1550.96, 1471.63, 1685.78, 1691.61 and 1551.67 Da, respectively. The FTIR spectrum of BSCP revealed the possibility that the extract contains β-glucan, which can be considered a valuable compound for the medical and food industries. These relate to the resistance of BSCP towards artificial human gastric juice which is more than 99%. Prebiotic activity tested using BSCP as a carbon source showed significant increase in the growth of B. animalis ATCC 1053, B. longum BB 536 and L. acidophilus ATCC 4356 as compared to the use of FOS. Survivality of S. choleraesuis JCM 6977 was found to be slower in both BSCP and FOS. Study conducted reflects a good sign for the BSCP to be exploited as a promising prebiotic.
    MeSH terms: Anion Exchange Resins; Chromatography, Ion Exchange; Gastric Juice; Humans; Molecular Weight; Polysaccharides/isolation & purification; Polysaccharides/pharmacology*; Polysaccharides/chemistry; Spectroscopy, Fourier Transform Infrared; Bambusa/chemistry*; Prebiotics*
  20. Single-stranded DNA (ssDNA) production in DNA aptamer generation
    Marimuthu C, Tang TH, Tominaga J, Tan SC, Gopinath SC
    Analyst, 2012 Mar 21;137(6):1307-15.
    PMID: 22314701 DOI: 10.1039/c2an15905h
    The discovery that synthetic short chain nucleic acids are capable of selective binding to biological targets has made them to be widely used as molecular recognition elements. These nucleic acids, called aptamers, are comprised of two types, DNA and RNA aptamers, where the DNA aptamer is preferred over the latter due to its stability, making it widely used in a number of applications. However, the success of the DNA selection process through Systematic Evolution of Ligands by Exponential Enrichment (SELEX) experiments is very much dependent on its most critical step, which is the conversion of the dsDNA to ssDNA. There is a plethora of methods available in generating ssDNA from the corresponding dsDNA. These include asymmetric PCR, biotin-streptavidin separation, lambda exonuclease digestion and size separation on denaturing-urea PAGE. Herein, different methods of ssDNA generation following the PCR amplification step in SELEX are reviewed.
    MeSH terms: Animals; Biotin/metabolism; Biotin/chemistry; DNA/genetics; DNA/metabolism; DNA/chemistry*; DNA, Single-Stranded/chemical synthesis*; DNA, Single-Stranded/chemistry; Exodeoxyribonucleases/metabolism; Polymerase Chain Reaction/methods; Streptavidin/metabolism; Streptavidin/chemistry; SELEX Aptamer Technique/methods*; Aptamers, Nucleotide/chemical synthesis*; Aptamers, Nucleotide/chemistry
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