The Experts below are selected from a list of 37611 Experts worldwide ranked by ideXlab platform

Yaping Zhang - One of the best experts on this subject based on the ideXlab platform.

  • pleistocene isolation in the northwestern pacific marginal seas and limited dispersal in a marine fish chelon haematocheilus temminck schlegel 1845
    Molecular Ecology, 2006
    Co-Authors: Shifang Wu, Yaping Zhang
    Abstract:

    The Northwestern Pacific has a unique tectonic and geographical history with several marginal seas separating Asia from the Pacific Ocean. During low sea level periods of Pleistocene glaciations, Populations might have been isolated in three marginal seas: the Sea of Japan, East China Sea and South China Sea. Following postglacial sea level rise, we would expect the Populations isolated in the three regions to have been homogenized by high dispersal potential. To assess these hypotheses, we explore the intraspecific phylogeographical patterns in redlip mullet, Chelon haematocheilus. Fragments of 435 bp at the 5′ end of mitochondrial DNA control region were sequenced for 272 individuals from nine localities over most of the species’ range. Three distinct lineages were detected, which might have diverged in the three marginal seas during Pleistocene low sea levels. Contrary to homogenization expectation, there were strong differences in the geographical distribution of the three lineages. Analyses of molecular variance and the Population Statistic ΦST also revealed significant genetic structure among Populations of the three marginal seas. These results indicate that gene flow in Chelon haematocheilus is far more restricted spatially than predicted by the potential dispersal capabilities of this species. The lack of phylogeographical structure in East China Sea may reflect a recent range expansion after the last glacial maximum and insufficient time to attain migration-drift equilibrium.

  • late pleistocene divergence and subsequent Population expansion of two closely related fish species japanese anchovy engraulis japonicus and australian anchovy engraulis australis
    Molecular Phylogenetics and Evolution, 2006
    Co-Authors: Jinxian Liu, Tianxiang Gao, Zhimeng Zhuang, Xianshi Jin, Koji Yokogawa, Yaping Zhang
    Abstract:

    Abstract Climatic oscillations during the Pleistocene ice ages produced great changes in species’ geographical distribution and abundance, which could be expected to have genetic consequences. Living in the temperate upwelling zones of the northwestern Pacific, Japanese anchovy ( Engraulis japonicus ) might have been affected by these severe climatic oscillations. To investigate the effects of Pleistocene climatic changes on the evolution in Japanese anchovy, fragments of 522 bp at the 5′ end of mitochondrial DNA control region were sequenced for 241 individuals from 13 localities and 37 individuals of Australian anchovy. Japanese anchovy and Australian anchovy are reciprocally monophyletic and a late Pleistocene transequatorial divergence between the two species was indicated. High levels of haplotype diversity (>0.99) were found for all samples, indicating a high level of genetic diversity. Analyses of molecular variance and the conventional Population Statistic F ST revealed no significant genetic structure throughout the range of Japanese anchovy. Both mismatch distribution analyses and neutrality tests suggested a late Pleistocene Population expansion for both Japanese anchovy (79,000–317,000 years ago) and Australian anchovy (45,000–178,000 years ago).

Jonathan Aldis - One of the best experts on this subject based on the ideXlab platform.

  • Down's syndrome screening : Population Statistic dependency of screening performance
    Clinical chemistry and laboratory medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p

  • down s syndrome screening Population Statistic dependency of screening performance
    Clinical Chemistry and Laboratory Medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p<0.001). At a cut-off of 1 in 250, the maximum triple test detection rate was 75.8% for a false positive rate of 4.9% and was obtained with the measurement procedure-specific setting. At a fixed false positive rate of 5%, the maximum detection rate for the triple test was 77.9% (95% Cl: 62.2%-85.8%). The maximum double test detection rate at 5% false positive rate was 69.6% (95% Cl: 59.5%-78.5%). Except for two models, the area under the curve for the triple test was higher than that of the double test. Conclusions: The Access triple test meets the typical performance characteristics for this test combination. The assay-specific settings yielded the overall best efficacy for the criteria studied. Therefore, the availability of measurement procedure-specific mid-trimester reference values for unaffected and affected pregnancies in prenatal screening programs is essential. Such reference values are established for the Beckman Coulter Access triple test: maternal serum AFP, uE 3 and hCG.

Timothy M Reynolds - One of the best experts on this subject based on the ideXlab platform.

  • Down's syndrome screening : Population Statistic dependency of screening performance
    Clinical chemistry and laboratory medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p

  • down s syndrome screening Population Statistic dependency of screening performance
    Clinical Chemistry and Laboratory Medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p<0.001). At a cut-off of 1 in 250, the maximum triple test detection rate was 75.8% for a false positive rate of 4.9% and was obtained with the measurement procedure-specific setting. At a fixed false positive rate of 5%, the maximum detection rate for the triple test was 77.9% (95% Cl: 62.2%-85.8%). The maximum double test detection rate at 5% false positive rate was 69.6% (95% Cl: 59.5%-78.5%). Except for two models, the area under the curve for the triple test was higher than that of the double test. Conclusions: The Access triple test meets the typical performance characteristics for this test combination. The assay-specific settings yielded the overall best efficacy for the criteria studied. Therefore, the availability of measurement procedure-specific mid-trimester reference values for unaffected and affected pregnancies in prenatal screening programs is essential. Such reference values are established for the Beckman Coulter Access triple test: maternal serum AFP, uE 3 and hCG.

Guido Vranken - One of the best experts on this subject based on the ideXlab platform.

  • Down's syndrome screening : Population Statistic dependency of screening performance
    Clinical chemistry and laboratory medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p

  • down s syndrome screening Population Statistic dependency of screening performance
    Clinical Chemistry and Laboratory Medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p<0.001). At a cut-off of 1 in 250, the maximum triple test detection rate was 75.8% for a false positive rate of 4.9% and was obtained with the measurement procedure-specific setting. At a fixed false positive rate of 5%, the maximum detection rate for the triple test was 77.9% (95% Cl: 62.2%-85.8%). The maximum double test detection rate at 5% false positive rate was 69.6% (95% Cl: 59.5%-78.5%). Except for two models, the area under the curve for the triple test was higher than that of the double test. Conclusions: The Access triple test meets the typical performance characteristics for this test combination. The assay-specific settings yielded the overall best efficacy for the criteria studied. Therefore, the availability of measurement procedure-specific mid-trimester reference values for unaffected and affected pregnancies in prenatal screening programs is essential. Such reference values are established for the Beckman Coulter Access triple test: maternal serum AFP, uE 3 and hCG.

Jan Van Nueten - One of the best experts on this subject based on the ideXlab platform.

  • Down's syndrome screening : Population Statistic dependency of screening performance
    Clinical chemistry and laboratory medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p

  • down s syndrome screening Population Statistic dependency of screening performance
    Clinical Chemistry and Laboratory Medicine, 2008
    Co-Authors: Timothy M Reynolds, Guido Vranken, Jan Van Nueten, Jonathan Aldis
    Abstract:

    Background: The choice of parameter sets used to calculate Down's syndrome risks is important. This study details analysis of samples from affected and unaffected pregnancies and evaluates whether published Population data is optimal. Screening efficiency realized with measurement procedure-specific Population parameters is compared with selected Population sets available in the literature. Methods: In a retrospective experiment, double and triple testing was performed on maternal serum samples from 286 randomly chosen unaffected singleton pregnancies and 95 Down's syndrome affected pregnancy samples. Using a risk cut-off of 1 in 250, detection rates and false positive rates were estimated for different Population settings to select a model giving the best overall efficacy. Receiver operation characteristics curve analysis was performed and detection rates realized with the different Population settings was estimated at a 5% fixed false positive rate. Results: Geometric mean weight corrected multiples of the median values were 1.01 for α-fetoprotein (AFP), 1.02 for human chorionic gonadotropin (hCG) and 1.01 for unconjugated estriol (uE 3 ) in unaffected pregnancies and 0.77 (95% Cl: 0.71-0.83) for AFP, 2.42 (95% Cl: 2.17-2.71) for hCG and 0.78 (95% Cl: 0.73-0.83) for uE 3 in affected pregnancies. Differences in double and triple risks obtained with the different models were significantly different from each other (p<0.001). At a cut-off of 1 in 250, the maximum triple test detection rate was 75.8% for a false positive rate of 4.9% and was obtained with the measurement procedure-specific setting. At a fixed false positive rate of 5%, the maximum detection rate for the triple test was 77.9% (95% Cl: 62.2%-85.8%). The maximum double test detection rate at 5% false positive rate was 69.6% (95% Cl: 59.5%-78.5%). Except for two models, the area under the curve for the triple test was higher than that of the double test. Conclusions: The Access triple test meets the typical performance characteristics for this test combination. The assay-specific settings yielded the overall best efficacy for the criteria studied. Therefore, the availability of measurement procedure-specific mid-trimester reference values for unaffected and affected pregnancies in prenatal screening programs is essential. Such reference values are established for the Beckman Coulter Access triple test: maternal serum AFP, uE 3 and hCG.