Displaying publications 1 - 20 of 92 in total

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  1. Duff IF, Mikkelsen WM, Dodge HJ, Himes DS
    Arthritis Rheum., 1968 Apr;11(2):184-90.
    PMID: 5645731 DOI: 10.1002/art.1780110209
    Matched MeSH terms: Colorimetry
  2. Buttery JE, de Witt GF, Omar Ahmad U
    Med J Malaya, 1968 Sep;23(1):54-7.
    PMID: 4237558
    Matched MeSH terms: Colorimetry
  3. Buttery JE, de Witt GF, Ahmad UO
    Med J Malaya, 1969 Jun;23(4):265-8.
    PMID: 4242173
    Matched MeSH terms: Colorimetry
  4. Abdullah P, Nainggolan H
    Environ Monit Assess, 1991 Oct;19(1-3):423-31.
    PMID: 24233958 DOI: 10.1007/BF00401330
    Phenolic chemicals with their very low taste and odour thresholds, high persistence and toxicity, are of growing concern as water pollutants. The compounds are known to exist in raw water as well as in treated water. The level of phenolic priority pollutants in water within the catchment area of the Linggi River Treatment Plant in Negeri Sembilan, Malaysia, which includes the Linggi river basin, was monitored. The 4-aminoantipyrin colourimetric method was used to determine total phenols whereas capillary column gas chromatography was used to determine the individual compounds. The results show that at most sampling stations, particularly those within the Seremban municipality, the level of phenols was found to exceed the recommended Malaysian standard of 2.0 μg/L(-1) for raw water. This is seen as the direct impact of industrial and urbanization of the area and clearly indicates the unhealthy state of the Linggi river. The results also indicate the need to improve the water quality if the river is going to be used as a source of raw water.
    Matched MeSH terms: Colorimetry
  5. Ng ML, Sazali BS, Khalid BA
    Ann. Clin. Biochem., 1991 Nov;28 ( Pt 6):613-7.
    PMID: 1776812
    A filter method for collection and storage of capillary blood spots for glycated haemoglobin (gHb) has been developed. Glass fibre filters (GFB) impregnated with 0.8 M boric acid were used to collect and store capillary blood. Haemoglobin from the dried blood spots was eluted into water and determined by Drabkin's method, while gHb in the eluates was determined by the microcolorimetric method. The intraassay coefficients of variation (CVs) were 4.5, 4.5 and 3.1% at 882, 1101 and 1704 pmol HMF/mg Hb, respectively. The corresponding inter-assay CVs were 8.6, 8.6 and 6.3%, respectively. A total of 63 paired capillary and venous blood samples were measured by both the direct and GFB method. The GFB method showed excellent correlation with the direct method (r = 0.948 and r = 0.994) after 7 and 14 days' storage at room temperature. The GFB method will enable prior collection and postage of blood samples by patients.
    Matched MeSH terms: Colorimetry/methods
  6. Lee HL, Tadano T
    PMID: 7855659
    The ability to identify the occurrence of different resistance genotypes in field populations of mosquito is considered important for the purpose of optimising chemical control operations. The recent development of rapid microassays of enzymes responsible for resistance has provided a means for rapidly assessing the genetic background of target mosquito populations. This concept is the topic of investigation in this study. Non-specific esterase activity, which is responsible for the resistance to organophosphates in Malaysian Culex quinquefasciatus Say adults, was determined in 3 field populations from Kuala Lumpur City using rapid enzyme assay. The optical density results were used to estimate the genotypic frequencies of the populations. Subsequently, time-dependent changes in the various frequencies were determined. Such techniques allowed rapid assessment of resistance genotypes for decision-making and its possible use in insect control merits further investigation.
    Matched MeSH terms: Colorimetry/methods
  7. Kho CL, Mohd-Azmi ML, Arshad SS, Yusoff K
    J Virol Methods, 2000 Apr;86(1):71-83.
    PMID: 10713378
    A sensitive and specific RT-nested PCR coupled with an ELISA detection system for detecting Newcastle disease virus is described. Two nested pairs of primer which were highly specific to all the three different pathotypes of NDV were designed from the consensus fusion gene sequence. No cross-reactions with other avian infectious agents such as infectious bronchitis virus, infectious bursal disease virus, influenza virus, and fowl pox virus were observed. Based on agarose electrophoresis detection, the RT-nested PCR was about 100 times more sensitive compared to that of a non-nested RT-PCR. To facilitate the detection of the PCR product, an ELISA detection method was then developed to detect the amplified PCR products and it was shown to be ten times more sensitive than gel electrophoresis. The efficacy of the nested PCR-ELISA was also compared with the conventional NDV detection method (HA test) and non-nested RT-PCR by testing against a total of 35 tissue specimens collected from ND-symptomatic chickens. The RT-nested PCR ELISA found NDV positive in 21 (60%) tissue specimens, while only eight (22.9%) and two (5.7%) out of 35 tissue specimens were tested NDV positive by both the non-nested RT-PCR and conventional HA test, respectively. Due to its high sensitivity for the detection of NDV from tissue specimens, this PCR-ELISA based diagnostic test may be useful for screening large number of samples.
    Matched MeSH terms: Colorimetry/methods
  8. Ihtatho D, Fadzil MH, Affandi AM, Hussein SH
    PMID: 18002738
    Psoriasis is a skin disorder which is caused by genetic fault. There is no cure for psoriasis, however, there are many treatment modalities to help control the disease. To evaluate treatment efficacy, PASI (Psoriasis Area and Severity Index) which is the current gold standard method is used to measure psoriasis severity by evaluating the area, erythema, scaliness and thickness of the plaques. However, the calculation of PASI can be tedious and subjective. In this work, we develop a computer vision method that determines one of the PASI parameter, the lesion area. The method isolates healthy (or healed) skin areas from lesion areas by analyzing the hue and chroma information in the CIE L*a*b* colour space. Centroids of healthy skin and psoriasis in the hue-chroma space are determined from selected sample. Euclidean distance of all pixels from each centroid is calculated. Each pixel is assigned to the class with minimum Euclidean distance. The study involves patients from three different ethnic origins having different skin tones. Results obtained show that the proposed method is comparable to the dermatologist visual approach.
    Matched MeSH terms: Colorimetry/methods*
  9. Nugroho H, Fadzil MH, Yap VV, Norashikin S, Suraiya HH
    PMID: 18002737
    In this paper, we describe an image processing scheme to analyze and determine areas of skin that have undergone repigmentation in particular, during the treatment of vitiligo. In vitiligo cases, areas of skin become pale or white due to the lack of skin pigment called melanin. Vitiligo treatment causes skin repigmentation resulting in a normal skin color. However, it is difficult to determine and quantify the amount of repigmentation visually during treatment because the repigmentation progress is slow and moreover changes in skin color can only be discerned over a longer time frame typically 6 months. Here, we develop a digital image analysis scheme that can identify and determine vitiligo skin areas and repigmentation progression on a shorter time period. The technique is based on principal component analysis and independent component analysis which converts the RGB skin image into a skin image that represent skin areas due to melanin and haemoglobin only, followed by segmentation process. Vitiligo skin lesions are identified as skin areas that lack melanin (non-melanin areas). In the initial studies of 4 patients, the method has been able to quantify repigmentation in vitiligo lesion. Hence it is now possible to determine repigmentation progression objectively and treatment efficacy on a shorter time cycle.
    Matched MeSH terms: Colorimetry/methods*
  10. Sosroseno W, Sugiatno E
    Acta Biomed, 2008 Aug;79(2):110-6.
    PMID: 18788505
    BACKGROUND AND AIMS OF THE WORK: Nitric oxide (NO) has been reported to enhance the production of cAMP by hydroxyapatite (HA)-induced a human osteoblast cell line (HOS cells). The aim of the present study was to test the hypothesis that exogenous NO may up-regulate the proliferation of hydroxyapatite (HA)-induced HOS cells via the cyclic-AMP-protein kinase A (PKA) pathway.
    Matched MeSH terms: Colorimetry
  11. Gan CY, Alkarkhi AF, Easa AM
    J Biosci Bioeng, 2009 Apr;107(4):366-72.
    PMID: 19332294 DOI: 10.1016/j.jbiosc.2008.12.007
    D-optimal design was employed to optimize the mixture of cross-linking agents formulation: microbial transglutaminase (MTGase) and ribose, and the processing parameters (i.e. incubation and heating time) in the mixture in order to obtain combined-cross-linked bovine serum albumin gels that have high gel strength, pH close to neutral and yet medium in browning. Analysis of variance (ANOVA) showed that the contribution of quadratic term to the model over the linear was significant for pH and L* value, whereas linear model was significant for gel strength. Optimization study using response surface methodology (RSM) was performed to the mixture components and process variables and the optimum conditions obtained were: MTGase of 1.34-1.43 g/100 mL, ribose of 1.07-1.16 g/100 mL, incubation time of 5 h at 40 degrees C and heating time of 3 h at 90 degrees C.
    Matched MeSH terms: Colorimetry
  12. Abdullah WZ, Idris SZ, Bashkar S, Hassan R
    Singapore Med J, 2009 Jun;50(6):604-9.
    PMID: 19551314
    The fibrinolytic system plays an important role in normal haemostasis and endothelial function. This study was conducted to compare three fibrinolytic markers, i.e. plasminogen, tissue-plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1) between acute stroke and stable non-stroke patients and to investigate the clinical significance of these markers.
    Matched MeSH terms: Colorimetry/methods
  13. Lutfi AN, Kannan TP, Fazliah MN, Jamaruddin MA, Saidi J
    Aust Dent J, 2010 Mar;55(1):79-85.
    PMID: 20415916 DOI: 10.1111/j.1834-7819.2009.01185.x
    The biological examination of pulp injury, repair events and response of dental pulp stem cells to dental restorative materials is important to accomplish restorative treatment, especially to commonly used dental materials in paediatric dentistry, such as glass ionomer cement (GIC) and calcium hydroxide (Ca(OH)(2)) lining cement.
    Matched MeSH terms: Colorimetry
  14. Nur Hazimah Abdul Halim, Norfazrin Mohd Hanif, Mohamed Rozali Othman, Mohd Talib Latif
    Sains Malaysiana, 2010;39:175-179.
    Surfactants in the atmosphere may act as cloud condensation nuclei, with a potentially negative impact on the global climate. Therefore, accurate determination of surfactants is crucial in order to investigate the possible effects of surfactants on the atmosphere. The aim of this study was to identify the optimum sampling method for measuring the maximum quantity of surfactants present in ambient air. Air samples were collected using a range of air sampling pumps that were made to vary in terms of flow rate, storage period, type of absorbing solution and the characteristics of the impinger tube. Samples obtained were analysed by colourimetry for anionic and cationic surfactants as methylene blue-active substances (MBAS) and disulphine blue-active substances (DBAS), respectively. Absorbance was measured at 650 nm for MBAS and 628 nm for DBAS using UV-visible spectrophotometer. We found that the optimum sampling method consisted of an absorbent solution (deionised water, buffer solution and methylene blue/disulphine blue solution) with the flow rate of 1.0 L/min. The concentration of surfactants in all sampling methods remained constant regardless of the storage period (1 day and 4 days), indicating that surfactants in the absorbing solution are quite stable. Covering the impinger tube was shown to influence the amount of both anionic and cationic surfactants detected.
    Matched MeSH terms: Colorimetry
  15. Hussain H, Mohd Fuat AR, Vimala B, Ghazali HM
    Trop Biomed, 2011 Aug;28(2):351-61.
    PMID: 22041756
    Assessment of amino acid decarboxylase activity can be conducted using tubed broth or plated agar. In this study, the test was carried out in microtitre plates containing lysine, ornithine, arginine, tyrosine, tryptophan, phenylalanine or histidine as biogenic amine precursors. Møller decarboxylase base broth (MDB) with or without 1% of a known amino acid were added to wells of a 96 well-microtitre plate. The wells were inoculated with Escherichia coli, Klebsiella pneumoniae, Acinetobacter anitratus or Staphylococcus aureus to the final concentration of 6.0 x 10(7) cfu/ml and incubated at 35ºC. The absorbance of the culture broth was read at 570 nm at 0, 1.0, 2.0, 3.0, 4.0, 5.5, 6.5 and 7.5 hour. Comparison of means of A'(570) between 0 hour and a specified incubation time was determined statistically. Positive decarboxylase activities were detected in the media inoculated with E. coli and K. pneumoniae in less than 6 hours. The current method is suitable for immediate producers of amino acid decarboxylase enzymes. It costs less as it uses less amino acid and it has the potential to be used for screening aliquots of food materials for amino acid decarboxylase activities.
    Matched MeSH terms: Colorimetry/economics; Colorimetry/methods
  16. Abdelwahab SI, Mohan S, Mohamed Elhassan M, Al-Mekhlafi N, Mariod AA, Abdul AB, et al.
    PMID: 21234328 DOI: 10.1155/2011/156765
    Antiapoptotic and antioxidant activities of aqueous-methanolic extract (CAME) of Orthosiphonstamineus Benth(OS), and its hexane (HF), chloroform (CF), n-butanol (NBF), ethyl acetate (EAF) and water (WF) fractions were investigated. Antioxidant properties were evaluated using the assays of Folin-Ciocalteu, aluminiumtrichloride, β-carotene bleaching and DPPH. The role of OS against hydrogen peroxide induced apoptosis on MDA-M231 epithelial cells was examined using MTT assay, phase contrast microscope, colorimetric assay of caspase-3, western blot and quantitative real-time PCR. Results showed that EAF showed the highest total phenolic content followed by CAME, NBF, WF, CF and HF, respectively. Flavonoid content was in the order of the CF > EAF > HF > CAME > NBF > WF. The IC(50) values on DPPH assay for different extract/fractions were 126.2 ± 23, 31.25 ± 1.2, 15.25 ± 2.3, 13.56 ± 1.9, 23.0 ± 3.2, and 16.66 ± 1.5 μg/ml for HF, CF, EAF, NBF, WF and CAME, respectively. OSreduced the oxidation of β-carotene by hydroperoxides. Cell death was dose-dependently inhibited by pretreatment with OS. Caspase-3 and distinct morphological features suggest the anti-apoptotic activities of OS. This plant not only increased the expression of Bcl-2, but also decreased Bax expression, and ultimately reduced H(2)O(2)-induced apoptosis. The current results showed that phenolics may provide health and nutritional benefits.
    Matched MeSH terms: Colorimetry
  17. Nilghaz A, Wicaksono DH, Gustiono D, Abdul Majid FA, Supriyanto E, Abdul Kadir MR
    Lab Chip, 2012 Jan 7;12(1):209-18.
    PMID: 22089026 DOI: 10.1039/c1lc20764d
    This paper describes the fabrication of microfluidic cloth-based analytical devices (μCADs) using a simple wax patterning method on cotton cloth for performing colorimetric bioassays. Commercial cotton cloth fabric is proposed as a new inexpensive, lightweight, and flexible platform for fabricating two- (2D) and three-dimensional (3D) microfluidic systems. We demonstrated that the wicking property of the cotton microfluidic channel can be improved by scouring in soda ash (Na(2)CO(3)) solution which will remove the natural surface wax and expose the underlying texture of the cellulose fiber. After this treatment, we fabricated narrow hydrophilic channels with hydrophobic barriers made from patterned wax to define the 2D microfluidic devices. The designed pattern is carved on wax-impregnated paper, and subsequently transferred to attached cotton cloth by heat treatment. To further obtain 3D microfluidic devices having multiple layers of pattern, a single layer of wax patterned cloth can be folded along a predefined folding line and subsequently pressed using mechanical force. All the fabrication steps are simple and low cost since no special equipment is required. Diagnostic application of cloth-based devices is shown by the development of simple devices that wick and distribute microvolumes of simulated body fluids along the hydrophilic channels into reaction zones to react with analytical reagents. Colorimetric detection of bovine serum albumin (BSA) in artificial urine is carried out by direct visual observation of bromophenol blue (BPB) colour change in the reaction zones. Finally, we show the flexibility of the novel microfluidic platform by conducting a similar reaction in a bent pinned μCAD.
    Matched MeSH terms: Colorimetry/instrumentation; Colorimetry/methods
  18. Abdullah N, Yuzir A, Curtis TP, Yahya A, Ujang Z
    Bioresour Technol, 2013 Jan;127:181-7.
    PMID: 23131639 DOI: 10.1016/j.biortech.2012.09.047
    Understanding the relationship between microbial community and mechanism of aerobic granulation could enable wider applications of granules for high-strength wastewater treatment. The majority of granulation studies principally determine the engineering aspects of granules formation with little emphasis on the microbial diversity. In this study, three identical reactors namely R1, R2 and R3 were operated using POME at volumetric loadings of 1.5, 2.5 and 3.5 kg COD m(-3) d(-1), respectively. Aeration was provided at a volumetric flow rate of 2.5 cms(-1). Aerobic granules were successfully developed in R2 and R3 while bioflocs dominated R1 until the end of experiments. Fractal dimension (D(f)) averaged at 1.90 suggesting good compactness of granules. The PCR-DGGE results indicated microbial evolutionary shift throughout granulation despite different operating OLRs based on decreased Raup and Crick similarity indices upon mature granule formation. The characteristics of aerobic granules treating high strength agro-based wastewater are determined at different volumetric loadings.
    Matched MeSH terms: Colorimetry
  19. Omar N, Loh Q, Tye GJ, Choong YS, Noordin R, Glökler J, et al.
    Sensors (Basel), 2013;14(1):346-55.
    PMID: 24379042 DOI: 10.3390/s140100346
    G-Quadruplex (G-4) structures are formed when G-rich DNA sequences fold into intra- or intermolecular four-stranded structures in the presence of metal ions. G-4-hemin complexes are often effective peroxidase-mimicking DNAzymes that are applied in many detection systems. This work reports the application of a G-rich daunomycin-specific aptamer for the development of an antibody-antigen detection assay. We investigated the ability of the daunomycin aptamer to efficiently catalyze the hemin-dependent peroxidase activity independent of daunomycin. A reporter probe consisting of biotinylated antigen and daunomycin aptamer coupled to streptavidin gold nanoparticles was successfully used to generate a colorimetric readout. In conclusion, the daunomycin aptamer can function as a robust alternative DNAzyme for the development of colorimetric assays.
    Matched MeSH terms: Colorimetry/methods*
  20. Baskaran G, Masdor NA, Syed MA, Shukor MY
    ScientificWorldJournal, 2013;2013:678356.
    PMID: 24194687 DOI: 10.1155/2013/678356
    Heavy metals pollution has become a great threat to the world. Since instrumental methods are expensive and need skilled technician, a simple and fast method is needed to determine the presence of heavy metals in the environment. In this study, an inhibitive enzyme assay for heavy metals has been developed using crude proteases from Coriandrum sativum. In this assay, casein was used as a substrate and Coomassie dye was used to denote the completion of casein hydrolysis. In the absence of inhibitors, casein was hydrolysed and the solution became brown, while in the presence of metal ions such as Hg²⁺ and Zn²⁺, the hydrolysis of casein was inhibited and the solution remained blue. Both Hg²⁺ and Zn²⁺ exhibited one-phase binding curve with IC₅₀ values of 3.217 mg/L and 0.727 mg/L, respectively. The limits of detection (LOD) and limits of quantitation (LOQ) for Hg were 0.241 and 0.802 mg/L, respectively, while the LOD and LOQ for Zn were 0.228 and 0.761 mg/L, respectively. The enzyme exhibited broad pH ranges for activity. The crude proteases extracted from Coriandrum sativum showed good potential for the development of a rapid, sensitive, and economic inhibitive assay for the biomonitoring of Hg²⁺ and Zn²⁺ in the aquatic environments.
    Matched MeSH terms: Colorimetry/methods*
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