Displaying publications 341 - 360 of 468 in total

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  1. Inhibitory effects of cytochrome P450 enzymes CYP2C8, CYP2C9, CYP2C19 and CYP3A4 by Labisia pumila extracts
    Pan Y, Tiong KH, Abd-Rashid BA, Ismail Z, Ismail R, Mak JW, et al.
    J Ethnopharmacol, 2012 Sep 28;143(2):586-91.
    PMID: 22885070 DOI: 10.1016/j.jep.2012.07.024
    Labisa pumila (LP), popularly known with its local name, Kacip Fatimah, is a well known herb grown in Indochina and Southeast Asia and is traditionally used to regain energy after giving birth in women. The propensity of LP to cause drug-herb interaction via cytochrome P450 (CYP) enzyme system has not been investigated.
    Matched MeSH terms: Water/chemistry
  2. Studies on seed germination and growth in weed species of rice field under salinity stress
    Hakim MA, Juraimi AS, Hanafi MM, Selamat A, Ismail MR, Karim SM
    J Environ Biol, 2011 Sep;32(5):529-36.
    PMID: 22319865
    An investigation was made to see the salt tolerance of 10 weed species of rice. Properly dried and treated seeds of weed species were placed on 9 cm diameter petridishes lined with Whatman No. 1 filter paper under 6 salinity regimes, viz. 0 (control), 4, 8, 16, 24 and 32 dS m(-1). The petri dishes were then kept in germinator at 25 +/- 1.0 degrees C and 12 hr light. The number of germinated seeds were recorded daily. The final germination percentage, germination index (GI), seedling vigour index, mean germination time and time for 50% germination were estimated. Root and shoot lengths of the weed seedlings were measured at 20 days after salt application and relative growth values were calculated. Results revealed that salinity decreased final germination percentage, seed of germination as measured by GI, and shoot and root length in all the species. Germination of most of the weed seeds was completely arrested (0) at 32 dS m(-1) salinity except in E. colona (12%) and C. iria (13.9%). The species C. iria, E. colona, J. linifolia and E. crusgalli showed better germination (above 30%) upto 24 dS m(-1) salinity level and were regarded as salt-tolerant weed species. J. linifolia, F. miliacea, L. chinensis and O. sativa L. (weedy rice) were graded as moderately tolerant and S. zeylanica, S. grosus and C. difformis were regarded as least tolerant weed species.
    Matched MeSH terms: Water/chemistry
  3. Characteristics of treated effluents and their potential applications for producing concrete
    Noruzman AH, Muhammad B, Ismail M, Abdul-Majid Z
    J Environ Manage, 2012 Nov 15;110:27-32.
    PMID: 22705857 DOI: 10.1016/j.jenvman.2012.05.019
    Conservation and preservation of freshwater is increasingly becoming important as the global population grows. Presently, enormous volumes of freshwater are used to mix concrete. This paper reports experimental findings regarding the feasibility of using treated effluents as alternatives to freshwater in mixing concrete. Samples were obtained from three effluent sources: heavy industry, a palm-oil mill and domestic sewage. The effluents were discharge into public drain without danger to human health and natural environment. Chemical compositions and physical properties of the treated effluents were investigated. Fifteen compositional properties of each effluent were correlated with the requirements set out by the relevant standards. Concrete mixes were prepared using the effluents and freshwater to establish a base for control performance. The concrete samples were evaluated with regard to setting time, workability, compressive strength and permeability. The results show that except for some slight excesses in total solids and pH, the properties of the effluents satisfy the recommended disposal requirements. Two concrete samples performed well for all of the properties investigated. In fact, one sample was comparatively better in compressive strength than the normal concrete; a 9.4% increase was observed at the end of the curing period. Indeed, in addition to environmental conservation, the use of treated effluents as alternatives to freshwater for mixing concrete could save a large amount of freshwater, especially in arid zones.
    Matched MeSH terms: Waste Water/chemistry*
  4. Electro polymerized 4-vinyl pyridine on 2B pencil graphite as ionophore for cadmium (II)
    Wee Ling JL, Khan A, Saad B, Ab Ghani S
    Talanta, 2012 Jan 15;88:477-83.
    PMID: 22265529 DOI: 10.1016/j.talanta.2011.11.018
    A new poly(4-vinyl pyridine) (P4VP) based cadmium (Cd)-ion selective electrode (ISE) was developed. The 4-vinyl pyridine (4VP) was first polymerized electrochemically on the surface of graphite, later characterized by FTIR, SEM/EDX and then optimized as ISE for Cd. At optimal pH 6.4, slope of 27.7±0.8mVdecade(-1), linear concentration range of 1×10(-7) to 1.0×10(-1)M Cd(2+) and limit of detection (S/N=3) of 2.51×10(-8)M were obtained. The ISE was very selective towards Cd(2+), with K(pot)<1×10(-2) in the presence of the usual cations and anions in water samples. Response time and shelf life of less than 1min and 90 days, respectively, were observed. Its application was tested in various types of samples.
    Matched MeSH terms: Water/chemistry
  5. Determination of radioactive elements and heavy metals in sediments and soil from domestic water sources in northern peninsular Malaysia
    Muhammad BG, Jaafar MS, Abdul Rahman A, Ingawa FA
    Environ Monit Assess, 2012 Aug;184(8):5043-9.
    PMID: 21901308 DOI: 10.1007/s10661-011-2320-3
    Soil serves as a major reservoir for contaminants as it posseses an ability to bind various chemicals together. To safeguard the members of the public from an unwanted exposure, studies were conducted on the sediments and soil from water bodies that form the major sources of domestic water supply in northern peninsular Malaysia for their trace element concentration levels. Neutron Activation Analysis, using Nigeria Research Reactor-1 (NIRR-1) located at the Centre for Energy Research and Training, Zaria, Nigeria was employed as the analytical tool. The elements identified in major quantities include Na, K, and Fe while As, Br, Cr, U, Th, Eu, Cs, Co, La, Sm, Yb, Sc, Zn, Rb, Ba, Lu, Hf, Ta, and Sb were also identified in trace quantities. Gamma spectroscopy was also employed to analyze some soil samples from the same area. The results indicated safe levels in terms of the radium equivalent activity, external hazard index as well as the mean external exposure dose rates from the soil. The overall screening of the domestic water sources with relatively high heavy metals concentration values in sediments and high activity concentration values in soil is strongly recommended as their accumulation overtime as a consequence of leaching into the water may be of health concern to the members of the public.
    Matched MeSH terms: Fresh Water/chemistry
  6. Fulltext 'Heat-treatment aqueous two phase system' for purification of serine protease from Kesinai (Streblus asper) leaves
    Mehrnoush A, Mustafa S, Yazid AM
    Molecules, 2011 Dec 08;16(12):10202-13.
    PMID: 22158589 DOI: 10.3390/molecules161210202
    A 'Heat treatment aqueous two phase system' was employed for the first time to purify serine protease from kesinai (Streblus asper) leaves. In this study, introduction of heat treatment procedure in serine protease purification was investigated. In addition, the effects of different molecular weights of polyethylene glycol (PEG 4000, 6000 and 8000) at concentrations of 8, 16 and 21% (w/w) as well as salts (Na-citrate, MgSO₄ and K₂HPO₄) at concentrations of 12, 15, 18% (w/w) on serine protease partition behavior were studied. Optimum conditions for serine protease purification were achieved in the PEG-rich phase with composition of 16% PEG6000-15% MgSO₄. Also, thermal treatment of kesinai leaves at 55 °C for 15 min resulted in higher purity and recovery yield compared to the non-heat treatment sample. Furthermore, this study investigated the effects of various concentrations of NaCl addition (2, 4, 6 and 8% w/w) and different pH (4, 7 and 9) on the optimization of the system to obtain high yields of the enzyme. The recovery of serine protease was significantly enhanced in the presence of 4% (w/w) of NaCl at pH 7.0. Based on this system, the purification factor was increased 14.4 fold and achieved a high yield of 96.7%.
    Matched MeSH terms: Water/chemistry*
  7. Fulltext Antidiabetic properties and mechanism of action of Gynura procumbens water extract in streptozotocin-induced diabetic rats
    Hassan Z, Yam MF, Ahmad M, Yusof AP
    Molecules, 2010;15(12):9008-23.
    PMID: 21150821 DOI: 10.3390/molecules15129008
    Gynura procumbens (Lour.) Merr (family Compositae) is cultivated in Southeast Asia, especially Indonesia, Malaysia and Thailand, for medicinal purposes. This study evaluated the in vivo hypoglycemic properties of the water extract of G. procumbens following 14 days of treatment and in vitro in RIN-5F cells. Glucose absorption from the intestines and its glucose uptake in abdominal skeletal muscle were assessed. The antidiabetic effect of water extract of G. procumbens leaves was investigated in streptozotocin-induced diabetic rats. The intraperitoneal glucose tolerance test (IPGTT) was performed in diabetic rats treated with G. procumbens water extract for 14 days. In the IPGTT, blood was collected for insulin and blood glucose measurement. After the IPGTT, the pancreases were collected for immunohistochemical study of β-cells of the islets of Langerhans. The possible antidiabetic mechanisms of G. procumbens were assessed through in vitro RIN-5F cell study, intestinal glucose absorption and glucose uptake by muscle. The results showed that G. procumbens significantly decreased blood glucose levels after 14 days of treatment and improved outcome of the IPGTT. However, G. procumbens did not show a significant effect on insulin level either in the in vivo test or the in vitro RIN-5F cell culture study. G. procumbens also showed minimal effects on β-cells of the islets of Langerhans in the pancreas. However, G. procumbens only significantly increased glucose uptake by muscle tissues. From the findings we can conclude that G. procumbens water extract exerted its hypoglycemic effect by promoting glucose uptake by muscles.
    Matched MeSH terms: Water/chemistry
  8. Fulltext Evaluation of antioxidant and antibacterial activities of aqueous, methanolic and alkaloid extracts from Mitragyna speciosa (Rubiaceae family) leaves
    Parthasarathy S, Bin Azizi J, Ramanathan S, Ismail S, Sasidharan S, Said MI, et al.
    Molecules, 2009;14(10):3964-74.
    PMID: 19924042 DOI: 10.3390/molecules14103964
    Studies on the antioxidant and antimicrobial activities of Mitragyna speciosa leaf extracts are lacking. In this study the antioxidant properties of water, methanolic and alkaloid M. speciosa leaf extracts were evaluated using the DPPH (2,2-diphenyl-1- picrylhydrazyl) radical scavenging method. The amount of total phenolics and flavanoid contents were also estimated. The DPPH IC(50) values of the aqueous, alkaloid and methanolic extracts were 213.4, 104.81 and 37.08 microg/mL, respectively. The total phenolic content of the aqueous, alkaloid and methanolic extracts were 66.0 mg, 88.4, 105.6 mg GAE/g, respectively, while the total flavanoid were 28.2, 20.0 and 91.1 mg CAE/g respectively. The antioxidant activities were correlated with the total phenolic content. This result suggests that the relatively high antioxidant activity of the methanolic extract compared to aqueous and alkaloid extract could be possibly be due to its high phenolic content. The aqueous, alkaloid and methanolic extracts were screened for antimicrobial activity. The extracts showed antimicrobial activity against Salmonella typhi and Bacillus subtilis. The minimum inhibitory concentrations (MICs) of extracts determined by the broth dilution method ranged from 3.12 to 6.25 mg/mL. The alkaloid extract was found to be most effective against all of the tested organisms.
    Matched MeSH terms: Water/chemistry
  9. Molecular insights into 14-membered macrolides using the MM-PBSA method
    Yam WK, Wahab HA
    J Chem Inf Model, 2009 Jun;49(6):1558-67.
    PMID: 19469526 DOI: 10.1021/ci8003495
    Erythromycin A and roxithromycin are clinically important macrolide antibiotics that selectively act on the bacterial 50S large ribosomal subunit to inhibit bacteria's protein elongation process by blocking the exit tunnel for the nascent peptide away from ribosome. The detailed molecular mechanism of macrolide binding is yet to be elucidated as it is currently known to the most general idea only. In this study, molecular dynamics (MD) simulation was employed to study their interaction at the molecular level, and the binding free energies for both systems were calculated using the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method. The calculated binding free energies for both systems were slightly overestimated compared to the experimental values, but individual energy terms enabled better understanding in the binding for both systems. Decomposition of results into residue basis was able to show the contribution of each residue at the binding pocket toward the binding affinity of macrolides and hence identified several key interacting residues that were in agreement with previous experimental and computational data. Results also indicated the contributions from van der Waals are more important and significant than electrostatic contribution in the binding of macrolides to the binding pocket. The findings from this study are expected to contribute to the understanding of a detailed mechanism of action in a quantitative matter and thus assisting in the development of a safer macrolide antibiotic.
    Matched MeSH terms: Water/chemistry
  10. Refinement of a low-resolution crystal structure to better understand erythromycin interactions on large ribosomal subunit
    Wahab HA, Yam WK, Samian MR, Najimudin N
    J Biomol Struct Dyn, 2008 Aug;26(1):131-46.
    PMID: 18533733
    Macrolides are a group of diverse class of naturally occurring and synthetic antibiotics made of macrocyclic-lactone ring carrying one or more sugar moieties linked to various atoms of the lactone ring. These macrolides selectively bind to a single high affinity site on the prokaryotic 50S ribosomal subunit, making them highly effective towards a wide range of bacterial pathogens. The understanding of binding between macrolides and ribosome serves a good basis in elucidating how they work at the molecular level and these findings would be important in rational drug design. Here, we report refinement of reconstructed PDB structure of erythromycin-ribosome system using molecular dynamics (MD) simulation. Interesting findings were observed in this refinement stage that could improve the understanding of the binding of erythromycin A (ERYA) onto the 50S subunit. The results showed ERYA was highly hydrated and water molecules were found to be important in bridging hydrogen bond at the binding pocket during the simulation time. ERYA binding to ribosome was also strengthened by hydrogen bond network and hydrophobic interactions between the antibiotic and the ribosome. Our MD simulation also demonstrated direct interaction of ERYA with Domains II, V and with C1773 (U1782EC), a residue in Domain IV that has yet been described of its role in ERYA binding. It is hoped that this refinement will serve as a starting model for a further enhancement of our understanding towards the binding of ERYA to ribosome.
    Matched MeSH terms: Water/chemistry
  11. Spent tea leaves: a new non-conventional and low-cost adsorbent for removal of basic dye from aqueous solutions
    Hameed BH
    J Hazard Mater, 2009 Jan 30;161(2-3):753-9.
    PMID: 18499346 DOI: 10.1016/j.jhazmat.2008.04.019
    In the present study, spent tea leaves (STL) were used as a new non-conventional and low-cost adsorbent for the cationic dye (methylene blue) adsorption in a batch process at 30 degrees C. Equilibrium sorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to the Langmuir isotherm and the monolayer adsorption capacity was found to be 300.052mg/g at 30 degrees C. The kinetic data obtained at different initial concentrations were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion equations. The results revealed that the spent tea leaves, being waste, have the potential to be used as a low-cost adsorbent for the removal of methylene blue from aqueous solutions.
    Matched MeSH terms: Water/chemistry
  12. Anti-proliferative and mutagenic activities of aqueous and methanol extracts of leaves from Pereskia bleo (Kunth) DC (Cactaceae)
    Er HM, Cheng EH, Radhakrishnan AK
    J Ethnopharmacol, 2007 Sep 25;113(3):448-56.
    PMID: 17698306
    The anti-proliferative effects of the aqueous and methanol extracts of leaves of Pereskia bleo (Kunth) DC (Cactaceae) against a mouse mammary cancer cell line (4T1) and a normal mouse fibroblast cell line (NIH/3T3) were evaluated under an optimal (in culture medium containing 10% foetal bovine serum (FBS)) and a sub-optimal (in culture medium containing 0.5% FBS) conditions. Under the optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in 4T1 cells and 300 microg/mL in NIH/3T3 cells, whereas the methanol extract did not show any notable anti-proliferative effect in these cell lines, at any of the concentrations tested. Under the sub-optimal condition, the aqueous extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in NIH/3T3 cells, whilst the methanol extract showed a significant (p<0.05) anti-proliferative effect at 200 microg/mL and 300 microg/mL in both cell lines. An upward trend of apoptosis was observed in both 4T1 and NIH/3T3 cells treated with increasing concentrations of the aqueous extract. The level of apoptosis observed at all the concentrations of the aqueous extract tested was consistently higher than necrosis. There was a significant (p<0.05) increase in the level of necrosis observed in the 4T1 cells treated with 300 microg/mL of the methanol extract. Generally, the level of necrosis was noted to be higher than that of apoptosis in the methanol extract-treated cells. The mutagenicity assay performed showed that in the absence of S-9 liver metabolic activation, the extract was not mutagenic up to the concentration of 165 microg/mL . However, in the presence of S-9 liver metabolic activation, the aqueous extract was mutagenic at all the concentrations tested. This study shows that both the aqueous and methanol extracts of the leaves from Pereskia bleo (Kunth) DC (Cactaceae) do not have appreciable anti-proliferative effect on the 4T1 and NIH/3T3 cells as the EC(50) values obtained are greater than 50 microg/mL when tested under optimal culture condition. Moreover, the aqueous extract may form mutagenic compound(s) upon the metabolisation by liver enzymes.
    Matched MeSH terms: Water/chemistry
  13. Bio-electrochemical removal of nitrate from water and wastewater--a review
    Ghafari S, Hasan M, Aroua MK
    Bioresour Technol, 2008 Jul;99(10):3965-74.
    PMID: 17600700
    Nitrates in different water and wastewater streams raised concerns due to severe impacts on human and animal health. Diverse methods are reported to remove nitrate from water streams which almost fail to entirely treat nitrate, except biological denitrification which is capable of reducing inorganic nitrate compounds to harmless nitrogen gas. Review of numerous studies in biological denitrification of nitrate containing water resources, aquaculture wastewaters and industrial wastewater confirmed the potential of this method and its flexibility towards the remediation of different concentrations of nitrate. The denitrifiers could be fed with organic and inorganic substrates which have different performances and subsequent advantages or disadvantages. Review of heterotrophic and autotrophic denitrifications with different food and energy sources concluded that autotrophic denitrifiers are more effective in denitrification. Autotrophs utilize carbon dioxide and hydrogen as the source of carbon substrate and electron donors, respectively. The application of this method in bio-electro reactors (BERs) has many advantages and is promising. However, this method is not so well established and documented. BERs provide proper environment for simultaneous hydrogen production on cathodes and appropriate consumption by immobilized autotrophs on these cathodes. This survey covers various designs and aspects of BERs and their performances.
    Matched MeSH terms: Water/chemistry*
  14. Fluoride exposure from ingested toothpaste in 4-5-year-old Malaysian children
    Siew Tan B, Razak IA
    Community Dent Oral Epidemiol, 2005 Oct;33(5):317-25.
    PMID: 16128790
    The aim of this study was to assess (by direct determination) the fluoride (F) exposure from ingested toothpaste among 4-5-year-old Malaysian children.
    Matched MeSH terms: Water/chemistry
  15. Fulltext Environmental Synthesis of Few Layers Graphene Sheets Using Ultrasonic Exfoliation with Enhanced Electrical and Thermal Properties
    Noroozi M, Zakaria A, Radiman S, Abdul Wahab Z
    PLoS One, 2016;11(4):e0152699.
    PMID: 27064575 DOI: 10.1371/journal.pone.0152699
    In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene.
    Matched MeSH terms: Water/chemistry
  16. Fulltext Presence of Cryptosporidium parvum and Giardia lamblia in water samples from Southeast Asia: towards an integrated water detection system
    Kumar T, Abd Majid MA, Onichandran S, Jaturas N, Andiappan H, Salibay CC, et al.
    Infect Dis Poverty, 2016 Jan 13;5:3.
    PMID: 26763230 DOI: 10.1186/s40249-016-0095-z
    Access to clean and safe drinking water that is free from pathogenic protozoan parasites, especially Cryptosporidium parvum and Giardia lamblia that cause gastrointestinal illness in humans, is still an issue in Southeast Asia (SEA). This study is the first attempt to detect the aforementioned protozoan parasites in water samples from countries in SEA, using real-time polymerase chain reaction (qPCR) assays.
    Matched MeSH terms: Drinking Water/chemistry
  17. Water fraction of edible medicinal fern Stenochlaena palustris is a potent α-glucosidase inhibitor with concurrent antioxidant activity
    Chai TT, Kwek MT, Ong HC, Wong FC
    Food Chem, 2015 Nov 1;186:26-31.
    PMID: 25976787 DOI: 10.1016/j.foodchem.2014.12.099
    This study aimed to isolate a potent antiglucosidase and antioxidant fraction from Stenochlaena palustris. Extraction was performed with hexane, chloroform, ethyl acetate, methanol, and water. Antiglucosidase, 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and ferric reducing antioxidant power (FRAP) assays found methanol extract (ME) to be the most active. Water fraction (WF) of ME was a stronger α-glucosidase inhibitor (EC50 2.9 μg/mL) than quercetin, with weak antiamylase activity. WF was a competitive α-glucosidase inhibitor. DPPH scavenging activity of WF (EC50 7.7 μg/mL) was weaker than quercetin. WF (EC50 364 μg/mL) was a stronger hydrogen peroxide scavenger than gallic acid (EC50 838 μg/mL) and was equally strong as quercetin in scavenging superoxide. WF possessed moderate copper chelating activity. WF was enriched in total phenolics (TP) and hydroxycinnamic acids (THC). TP correlated with antioxidant activity (R(2) > 0.76). Only THC correlated with antiglucosidase activity (R(2) = 0.86). Overall, WF demonstrated concurrent, potent antiglucosidase and antioxidant activities.
    Matched MeSH terms: Water/chemistry
  18. Fulltext Fructose-Drinking Water Induced Nonalcoholic Fatty Liver Disease and Ultrastructural Alteration of Hepatocyte Mitochondria in Male Wistar Rat
    Mamikutty N, Thent ZC, Haji Suhaimi F
    Biomed Res Int, 2015;2015:895961.
    PMID: 26273656 DOI: 10.1155/2015/895961
    BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) is one of the complications of the metabolic syndrome. It encompasses a wide range of disease spectrum from simple steatosis to liver cirrhosis. Structural alteration of hepatic mitochondria might be involved in the pathogenesis of NAFLD.

    AIMS: In the present study, we used a newly established model of fructose-induced metabolic syndrome in male Wistar rats in order to investigate the ultrastructural changes in hepatic mitochondria that occur with fructose consumption and their association with NAFLD pathogenesis.

    METHODS: The concentration of fructose-drinking water (FDW) used in this study was 20%. Six male Wistar rats were supplemented with FDW 20% for eight weeks. Body composition and metabolic parameters were measured before and after 8 weeks of FDW 20%. Histomorphology of the liver was evaluated and ultrastructural changes of mitochondria were assessed with transmission electron micrograph.

    RESULTS: After 8 weeks of fructose consumption, the animals developed several features of the metabolic syndrome. Moreover, fructose consumption led to the development of macrovesicular hepatic steatosis and mitochondrial ultrastructural changes, such as increase in mitochondrial size, disruption of the cristae, and reduction of matrix density.

    CONCLUSION: We conclude that in male Wistar rat 8-week consumption of FDW 20% leads to NAFLD likely via mitochondrial structural alteration.

    Matched MeSH terms: Drinking Water/chemistry
  19. Preliminary Assessment of Cyanobacteria Diversity and Toxic Potential in Ten Freshwater Lakes in Selangor, Malaysia
    Sinang SC, Poh KB, Shamsudin S, Sinden A
    Bull Environ Contam Toxicol, 2015 Oct;95(4):542-7.
    PMID: 26248788 DOI: 10.1007/s00128-015-1620-7
    Toxic cyanobacteria blooms are increasing in magnitude and frequency worldwide. However, this issue has not been adequately addressed in Malaysia. Therefore, this study aims to better understand eutrophication levels, cyanobacteria diversity, and microcystin concentrations in ten Malaysian freshwater lakes. The results revealed that most lakes were eutrophic, with total phosphorus and total chlorophyll-a concentrations ranging from 15 to 4270 µg L(-1) and 1.1 to 903.1 µg L(-1), respectively. Cyanobacteria were detected in all lakes, and identified as Microcystis spp., Planktothrix spp., Phormidium spp., Oscillatoria spp., and Lyngbya spp. Microcystis spp. was the most commonly observed and most abundant cyanobacteria recorded. Semi-quantitative microcystin analysis indicated the presence of microcystin in all lakes. These findings illustrate the potential health risk of cyanobacteria in Malaysia freshwater lakes, thus magnifying the importance of cyanobacteria monitoring and management in Malaysian waterways.
    Matched MeSH terms: Fresh Water/chemistry
  20. Modified enzymes for reactions in organic solvents
    Salleh AB, Basri M, Taib M, Jasmani H, Rahman RN, Rahman MB, et al.
    Appl Biochem Biotechnol, 2002 10 25;102-103(1-6):349-57.
    PMID: 12396136
    Recent studies on biocatalysis in water-organic solvent biphasic systems have shown that many enzymes retain their catalytic activities in the presence of high concentrations of organic solvents. However, not all enzymes are organic solvent tolerant, and most have limited and selective tolerance to particular organic solvents. Protein modification or protein tailoring is an approach to alter the characteristics of enzymes, including solubility in organic solvents. Particular amino acids may play pivotal roles in the catalytic ability of the protein. Attaching soluble modifiers to the protein molecule may alter its conformation and the overall polarity of the molecule. Enzymes, in particular lipases, have been chemically modified by attachment of aldehydes, polyethylene glycols, and imidoesters. These modifications alter the hydrophobicity and conformation of the enzymes, resulting in changes in the microenvironment of the enzymes. By these modifications, newly acquired properties such as enhancement of activity and stability and changes in specificity and solubility in organic solvents are obtained. Modified lipases were found to be more active and stable in organic solvents. The optimum water activity (a(w)) for reaction was also shifted by using modified enzymes. Changes in enantioselective behavior were also observed.
    Matched MeSH terms: Water/chemistry
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