The Experts below are selected from a list of 808398 Experts worldwide ranked by ideXlab platform
David A Saint - One of the best experts on this subject based on the ideXlab platform.
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validation of a Quantitative Method for real time pcr kinetics
Biochemical and Biophysical Research Communications, 2002Co-Authors: Weihong Liu, David A SaintAbstract:Real time RT-PCR is the most sensitive Method for quantitation of gene expression levels. The accuracy can be dependent on the mathematical model on which the Quantitative Methods are based. The generally accepted mathematical model assumes that amplification efficiencies are equal at the exponential phase of the reactions for the same amplicon. However, no Methods are available to test the assumptions regarding amplification efficiency before one starts the real time PCR quantitation. Here we further develop and test the validity of a new mathematical model which dynamically fits real time PCR data with good correlation (R 2 ¼ 0:9995 � 0:002, n ¼ 50). The Method is capable of measuring cycle-by-cycle PCR amplification efficiencies and demonstrates that these change dynamically. Validation of the Method revealed the intrinsic relationship between the initial amount of gene transcript and kinetic parameters. A new Quantitative Method is proposed which represents a simple but accurate Quantitative Method. 2002 Elsevier Science (USA). All rights reserved.
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a new Quantitative Method of real time reverse transcription polymerase chain reaction assay based on simulation of polymerase chain reaction kinetics
Analytical Biochemistry, 2002Co-Authors: Weihong Liu, David A SaintAbstract:Real-time reverse transcription (RT) PCR is currently the most sensitive Method for the detection of low-abundance mRNAs. Two relative Quantitative Methods have been adopted: the standard curve Method and the comparative C(T) Method. The latter is used when the amplification efficiency of a reference gene is equal to that of the target gene; otherwise the standard curve Method is applied. Based on the simulation of kinetic process of real-time PCR, we have developed a new Method for quantitation and normalization of gene transcripts. In our Method, the amplification efficiency for each individual reaction is calculated from the kinetic curve, and the initial amount of gene transcript is derived and normalized. Simulation demonstrated that our Method is more accurate than the comparative C(T) Method and would save more time than the relative standard curve Method. We have used the new Method to quantify gene expression levels of nine two-pore potassium channels. The relative levels of gene expression revealed by our Quantitative Method were broadly consistent with those estimated by routine RT-PCR, but the results also showed that amplification efficiencies varied from gene to gene and from sample to sample. Our Method provides a simple and accurate approach to quantifying gene expression level with the advantages that neither construction of standard curve nor validation experiments are needed.
Weihong Liu - One of the best experts on this subject based on the ideXlab platform.
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validation of a Quantitative Method for real time pcr kinetics
Biochemical and Biophysical Research Communications, 2002Co-Authors: Weihong Liu, David A SaintAbstract:Real time RT-PCR is the most sensitive Method for quantitation of gene expression levels. The accuracy can be dependent on the mathematical model on which the Quantitative Methods are based. The generally accepted mathematical model assumes that amplification efficiencies are equal at the exponential phase of the reactions for the same amplicon. However, no Methods are available to test the assumptions regarding amplification efficiency before one starts the real time PCR quantitation. Here we further develop and test the validity of a new mathematical model which dynamically fits real time PCR data with good correlation (R 2 ¼ 0:9995 � 0:002, n ¼ 50). The Method is capable of measuring cycle-by-cycle PCR amplification efficiencies and demonstrates that these change dynamically. Validation of the Method revealed the intrinsic relationship between the initial amount of gene transcript and kinetic parameters. A new Quantitative Method is proposed which represents a simple but accurate Quantitative Method. 2002 Elsevier Science (USA). All rights reserved.
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a new Quantitative Method of real time reverse transcription polymerase chain reaction assay based on simulation of polymerase chain reaction kinetics
Analytical Biochemistry, 2002Co-Authors: Weihong Liu, David A SaintAbstract:Real-time reverse transcription (RT) PCR is currently the most sensitive Method for the detection of low-abundance mRNAs. Two relative Quantitative Methods have been adopted: the standard curve Method and the comparative C(T) Method. The latter is used when the amplification efficiency of a reference gene is equal to that of the target gene; otherwise the standard curve Method is applied. Based on the simulation of kinetic process of real-time PCR, we have developed a new Method for quantitation and normalization of gene transcripts. In our Method, the amplification efficiency for each individual reaction is calculated from the kinetic curve, and the initial amount of gene transcript is derived and normalized. Simulation demonstrated that our Method is more accurate than the comparative C(T) Method and would save more time than the relative standard curve Method. We have used the new Method to quantify gene expression levels of nine two-pore potassium channels. The relative levels of gene expression revealed by our Quantitative Method were broadly consistent with those estimated by routine RT-PCR, but the results also showed that amplification efficiencies varied from gene to gene and from sample to sample. Our Method provides a simple and accurate approach to quantifying gene expression level with the advantages that neither construction of standard curve nor validation experiments are needed.
Robert Ritch - One of the best experts on this subject based on the ideXlab platform.
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ultrasound biomicroscopy dark room provocative testing a Quantitative Method for estimating anterior chamber angle width
Japanese Journal of Ophthalmology, 1999Co-Authors: Koji Esaki, Jeffrey M. Liebmann, Robert RitchAbstract:Abstract Purpose: To describe a Quantitative Method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). Methods: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 μm anterior to the scleral spur to the iris surface. ARA, and acceleration and y-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b , the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. Results: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 ± 0.04 vs. 0.15 ± 0.05 mm 2 , P t -test), acceleration a (0.22 ± 0.15 vs. 0.26 ± 0.17, P = .068), and y-intercept b (66 ± 46 vs. 92 ± 47 μm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions ( P = .1, paired t -test), while acceleration a did ( P P Conclusions: The ARA linear regression formula provides useful Quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.
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Ultrasound Biomicroscopy Dark Room Provocative Testing: ☆ ☆☆: A Quantitative Method for Estimating Anterior Chamber Angle Width
Japanese Journal of Ophthalmology, 1999Co-Authors: Koji Esaki, Jeffrey M. Liebmann, Robert RitchAbstract:Abstract Purpose: To describe a Quantitative Method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). Methods: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 μm anterior to the scleral spur to the iris surface. ARA, and acceleration and y-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b , the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. Results: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 ± 0.04 vs. 0.15 ± 0.05 mm 2 , P t -test), acceleration a (0.22 ± 0.15 vs. 0.26 ± 0.17, P = .068), and y-intercept b (66 ± 46 vs. 92 ± 47 μm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions ( P = .1, paired t -test), while acceleration a did ( P P Conclusions: The ARA linear regression formula provides useful Quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.
Koji Esaki - One of the best experts on this subject based on the ideXlab platform.
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ultrasound biomicroscopy dark room provocative testing a Quantitative Method for estimating anterior chamber angle width
Japanese Journal of Ophthalmology, 1999Co-Authors: Koji Esaki, Jeffrey M. Liebmann, Robert RitchAbstract:Abstract Purpose: To describe a Quantitative Method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). Methods: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 μm anterior to the scleral spur to the iris surface. ARA, and acceleration and y-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b , the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. Results: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 ± 0.04 vs. 0.15 ± 0.05 mm 2 , P t -test), acceleration a (0.22 ± 0.15 vs. 0.26 ± 0.17, P = .068), and y-intercept b (66 ± 46 vs. 92 ± 47 μm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions ( P = .1, paired t -test), while acceleration a did ( P P Conclusions: The ARA linear regression formula provides useful Quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.
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Ultrasound Biomicroscopy Dark Room Provocative Testing: ☆ ☆☆: A Quantitative Method for Estimating Anterior Chamber Angle Width
Japanese Journal of Ophthalmology, 1999Co-Authors: Koji Esaki, Jeffrey M. Liebmann, Robert RitchAbstract:Abstract Purpose: To describe a Quantitative Method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). Methods: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 μm anterior to the scleral spur to the iris surface. ARA, and acceleration and y-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b , the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. Results: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 ± 0.04 vs. 0.15 ± 0.05 mm 2 , P t -test), acceleration a (0.22 ± 0.15 vs. 0.26 ± 0.17, P = .068), and y-intercept b (66 ± 46 vs. 92 ± 47 μm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions ( P = .1, paired t -test), while acceleration a did ( P P Conclusions: The ARA linear regression formula provides useful Quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive.
Stephen J. Roberts - One of the best experts on this subject based on the ideXlab platform.
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Spore transmittance (% St): a Quantitative Method for spore colour analysis
Organic Geochemistry, 1999Co-Authors: Bridget Yule, Andrew D. Carr, John E. A. Marshall, Stephen J. RobertsAbstract:Abstract The progressive darkening of spores during burial is widely used as a maturation parameter in petroleum basins. The use of this parameter is limited by the subjective assessment of colour and the poor precision of the data. Using a spectral scanning microphotometer the spore colour can be recorded as the amount of light transmitted at different wavelengths in the visible spectrum. The spore transmittance value (% St ) is derived from: % St=100×T 550 /(T 450 ×T 650 ) , where T is the transmission at wavelengths of 450, 550 and 650 nm. The % St has been determined from spore colour (SCI) standards, artificially matured spores and pollen, and samples from two wells. The results show that the spore transmittance is determined by palynormorph type, and while this increases the range of % St values obtained in a single sample, the range of % St values obtained from different spore species within a sample overlap. The % St values increase with SCI values of spores used as SCI standards and with the temperature used in the laboratory maturation experiments. In the case of the geological samples the % St value increases with depth. The increase in spore transmittance (% St ) with increasing maturity shows that the Method has potential for use as a maturation parameter in hydrocarbon exploration.
