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A rapid quantitative lateral flow test for the detection of total aflatoxins in maize
1st International Conference on Molecular Diagnostic and Biomarker Discovery/Asian Pac J Trop Dis 2014; 4(3): 223-252
249
setting for the molecular dynamics simulation of Shigella flexneri outer membrane protein A. System
doi: 10.1016/S2222-1808(14)60562-4
襃 2014
1
by the Asian Pacific Journal of Tropical Disease. All rights reserved.
1
L. Y. H. Roy , and Y. S. Choong 1 Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia
ABSTRACT
Introduction: Shigellosis, also known as bacillus dysentery, is mainly caused by Shigella spp. Shigella flexneri 2a is a major public health concern contributing to the shigellosis endemic and mortality in the developing and under-developed countries. An outer membrane protein A (OmpA) from S. flexneri showed its potential as a biomarker in earlier work. Understanding the dynamics of the OmpA is essential to obtain an equilibrated structure which can aid in the design of a binder specific against S. flexneri OmpA for the future development of antibody-based shigellosis diagnostic. Objective: To set up an OmpA-membrane system for the molecular dynamics simulation. Methods: A previously modeled S. flexneri OmpA was embedded in phosphatidylethanolamine (POPE) lipid bilayer to mimic its natural environment. Water molecules and counter ions were added and the whole OmpA-membrane system was subsequently minimized to remove steric clashes. Results & Discussion: Results showed that OmpA is successfully inserted into the POPE membrane. The whole system consists of 306073 atoms. The plots of the kinetics, potentials, volume, pressure, density and temperature of the OmpA-POPE system are all stable and within acceptable range. Conclusion: The energy profiles from the minimization showed that the system is now ready to be further studied for its dynamics.
rapid quantitative lateral flow test for the detection of total aflatoxins in maize
A
doi: 10.1016/S2222-1808(14)60563-6 1
1
Poh Hong Goh , Michael Zheng
and Barbara Cvak2
襃 2014
by the Asian Pacific Journal of Tropical Disease. All rights reserved.
Romer Labs Singapore Pte Ltd, Jalan Bukit Merah #08-08, e-Centre@Redhill Building, Singapore 159471
1
Romer Labs Division Holding GmbH, Technopark 1, 3430 Tulln, Austria
2
ABSTRACT
Introduction: Aflatoxins (B1, B2, G1 and G2) are toxic secondary metabolites of, primarily, the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are potent carcinogens which cause liver diseases in livestock, domestic animals and humans throughout the world. Regulations for aflatoxins in commodities and food exist in more than 100 countries. A rapid quantitative lateral flow test, namely “Agrastrip”, was developed to measure total aflatoxin levels in maize. The test is developed based on the competitive immuno-chromatography principle. The total assay time for a sample extract is approximately 5 minutes. The results from the test are comparable to the reference HPLC or LC-MS/MS methods. Objective: To validate the quantitative AgraStrip total aflatoxin test in maize samples. Methods: Aflatoxins were extracted from ground maize sample using 70% methanol. To start an assay, buffer was added into a microwell to dissolve the pre-coated antibody-colloidal gold conjugate particle in the microwell. This was followed by mixing the dissolved conjugate with sample extract. A test strip was then placed into the mixture in microwell and incubated in a heat block incubator for 3 minutes. The test line zone in the test strip is able to capture the conjugate and form a visible line. The concentration of aflatoxins present in the sample is inversely proportional to the colour intensity of the test line. A line is always visible in positive control zone regardless of the presence of aflatoxins. The test strip is analyzed by the AgraVision® Reader and concentration of aflatoxins is determined. Results & Discussion: The test was able to measure aflatoxins in the range of 5-100μg/kg. Limit of detection for the test kit on corn sample was 3.6μg/kg. Accuracy and precision of the test on maize sample naturally contaminated with aflatoxins were comparable to the results form reference HPLC or LC-MS/MS methods. The shelf-life of the test kit was 12 months. Conclusion: Agrastrip total aflatoxin test is able to screen total aflatoxins in maize samples in its quantitation range.
249
setting for the molecular dynamics simulation of Shigella flexneri outer membrane protein A. System
doi: 10.1016/S2222-1808(14)60562-4
襃 2014
1
by the Asian Pacific Journal of Tropical Disease. All rights reserved.
1
L. Y. H. Roy , and Y. S. Choong 1 Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 Minden, Pulau Pinang, Malaysia
ABSTRACT
Introduction: Shigellosis, also known as bacillus dysentery, is mainly caused by Shigella spp. Shigella flexneri 2a is a major public health concern contributing to the shigellosis endemic and mortality in the developing and under-developed countries. An outer membrane protein A (OmpA) from S. flexneri showed its potential as a biomarker in earlier work. Understanding the dynamics of the OmpA is essential to obtain an equilibrated structure which can aid in the design of a binder specific against S. flexneri OmpA for the future development of antibody-based shigellosis diagnostic. Objective: To set up an OmpA-membrane system for the molecular dynamics simulation. Methods: A previously modeled S. flexneri OmpA was embedded in phosphatidylethanolamine (POPE) lipid bilayer to mimic its natural environment. Water molecules and counter ions were added and the whole OmpA-membrane system was subsequently minimized to remove steric clashes. Results & Discussion: Results showed that OmpA is successfully inserted into the POPE membrane. The whole system consists of 306073 atoms. The plots of the kinetics, potentials, volume, pressure, density and temperature of the OmpA-POPE system are all stable and within acceptable range. Conclusion: The energy profiles from the minimization showed that the system is now ready to be further studied for its dynamics.
rapid quantitative lateral flow test for the detection of total aflatoxins in maize
A
doi: 10.1016/S2222-1808(14)60563-6 1
1
Poh Hong Goh , Michael Zheng
and Barbara Cvak2
襃 2014
by the Asian Pacific Journal of Tropical Disease. All rights reserved.
Romer Labs Singapore Pte Ltd, Jalan Bukit Merah #08-08, e-Centre@Redhill Building, Singapore 159471
1
Romer Labs Division Holding GmbH, Technopark 1, 3430 Tulln, Austria
2
ABSTRACT
Introduction: Aflatoxins (B1, B2, G1 and G2) are toxic secondary metabolites of, primarily, the fungi Aspergillus flavus and Aspergillus parasiticus. Aflatoxins are potent carcinogens which cause liver diseases in livestock, domestic animals and humans throughout the world. Regulations for aflatoxins in commodities and food exist in more than 100 countries. A rapid quantitative lateral flow test, namely “Agrastrip”, was developed to measure total aflatoxin levels in maize. The test is developed based on the competitive immuno-chromatography principle. The total assay time for a sample extract is approximately 5 minutes. The results from the test are comparable to the reference HPLC or LC-MS/MS methods. Objective: To validate the quantitative AgraStrip total aflatoxin test in maize samples. Methods: Aflatoxins were extracted from ground maize sample using 70% methanol. To start an assay, buffer was added into a microwell to dissolve the pre-coated antibody-colloidal gold conjugate particle in the microwell. This was followed by mixing the dissolved conjugate with sample extract. A test strip was then placed into the mixture in microwell and incubated in a heat block incubator for 3 minutes. The test line zone in the test strip is able to capture the conjugate and form a visible line. The concentration of aflatoxins present in the sample is inversely proportional to the colour intensity of the test line. A line is always visible in positive control zone regardless of the presence of aflatoxins. The test strip is analyzed by the AgraVision® Reader and concentration of aflatoxins is determined. Results & Discussion: The test was able to measure aflatoxins in the range of 5-100μg/kg. Limit of detection for the test kit on corn sample was 3.6μg/kg. Accuracy and precision of the test on maize sample naturally contaminated with aflatoxins were comparable to the results form reference HPLC or LC-MS/MS methods. The shelf-life of the test kit was 12 months. Conclusion: Agrastrip total aflatoxin test is able to screen total aflatoxins in maize samples in its quantitation range.