The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Maria Donata Orfei - One of the best experts on this subject based on the ideXlab platform.
-
lc ms ms simultaneous analysis of allopregnanolone epiallopregnanolone pregnanolone Dehydroepiandrosterone and Dehydroepiandrosterone 3 sulfate in human plasma
Bioanalysis, 2017Co-Authors: Luana Lionetto, Fernando De Andres, Matilde Capi, Martina Curto, Donata Sabato, Maurizio Simmaco, Paola Bossu, Eleonora Sacchinelli, Maria Donata OrfeiAbstract:Aim: Several neuropsychopharmacological properties have been attributed to the 3α-reduced pregnane steroids, allopregnanolone and pregnanolone, as well as to Dehydroepiandrosterone sulfate because of their ability to modulate γ-aminobutyric acid (GABAA) receptors in the CNS. In order to understand better their role in several mechanisms in CNS, a new methodology is proposed to monitor these compounds in human plasma. Methodology & results: The analytes were first derivatized with 2-hydrazinopyridine and extracted from plasma using SPE. Then, the compounds were separated and detected by LC–MS/MS. A mobile phase of formic acid (0.1%) in water and methanol through a gradient of composition and a flow rate of 0.3 ml min-1 resulted in good separations of the analytes. Linear responses in wide range of concentrations and LOQs ranging from 10 (Dehydroepiandrosterone 3-sulfate) to 40 pg ml-1 (Dehydroepiandrosterone) were obtained in <9 min. The method proposed has been validated and then applied to monitor these ...
Martina Curto - One of the best experts on this subject based on the ideXlab platform.
-
lc ms ms simultaneous analysis of allopregnanolone epiallopregnanolone pregnanolone Dehydroepiandrosterone and Dehydroepiandrosterone 3 sulfate in human plasma
Bioanalysis, 2017Co-Authors: Luana Lionetto, Fernando De Andres, Matilde Capi, Martina Curto, Donata Sabato, Maurizio Simmaco, Paola Bossu, Eleonora Sacchinelli, Maria Donata OrfeiAbstract:Aim: Several neuropsychopharmacological properties have been attributed to the 3α-reduced pregnane steroids, allopregnanolone and pregnanolone, as well as to Dehydroepiandrosterone sulfate because of their ability to modulate γ-aminobutyric acid (GABAA) receptors in the CNS. In order to understand better their role in several mechanisms in CNS, a new methodology is proposed to monitor these compounds in human plasma. Methodology & results: The analytes were first derivatized with 2-hydrazinopyridine and extracted from plasma using SPE. Then, the compounds were separated and detected by LC–MS/MS. A mobile phase of formic acid (0.1%) in water and methanol through a gradient of composition and a flow rate of 0.3 ml min-1 resulted in good separations of the analytes. Linear responses in wide range of concentrations and LOQs ranging from 10 (Dehydroepiandrosterone 3-sulfate) to 40 pg ml-1 (Dehydroepiandrosterone) were obtained in <9 min. The method proposed has been validated and then applied to monitor these ...
Mark R Palmert - One of the best experts on this subject based on the ideXlab platform.
-
the longitudinal study of adrenal maturation during gonadal suppression evidence that adrenarche is a gradual process
The Journal of Clinical Endocrinology and Metabolism, 2001Co-Authors: Mark R Palmert, Douglas Hayden, Joan M Mansfield, J F Crigler, William F Crowley, Donald W Chandler, Paul A BoeppleAbstract:The physical changes that herald the onset of puberty result from the combination of adrenarche and gonadarche. To examine adrenal maturation and associated changes in growth without the confounding effects of changes in the gonadal steroid milieu, we performed a longitudinal study in 14 young girls with idiopathic central precocious puberty during long-term pituitary-gonadal suppression. Beginning at the mean age of 2.9 yr, Dehydroepiandrosterone sulfate levels, linear growth, skeletal maturation, body mass index, and secondary sexual development were evaluated at 3- to 6-month intervals for up to 12.3 yr. In 12 of the girls, levels of Dehydroepiandrosterone, androstenedione, 17-hydroxypregnenolone, and 17alpha-hydroxyprogesterone were determined before and after acute ACTH stimulation every 6 months to investigate the maturation of adrenal steroidogenic enzyme activity. Serum Dehydroepiandrosterone sulfate levels rose progressively throughout the study. An exponential model fit the longitudinal datasets well and indicated that Dehydroepiandrosterone sulfate levels increased approximately 22%/yr from the youngest age onward. Increasing activity of 17-20 lyase (CYP17) and decreasing activity of 3beta-hydroxysteroid dehydrogenase were also evident in preadrenarchal subjects. When controlled for chronological age, no significant associations were noted between weight, body mass index, or body surface area and Dehydroepiandrosterone sulfate levels. However, similar analyses revealed modest correlations of both height and growth velocity with Dehydroepiandrosterone sulfate levels. Our results suggest that adrenarche is not the result of sudden rapid changes in adrenal enzyme activities or adrenal androgen concentrations; rather, adrenarche may be a gradual maturational process that begins in early childhood.
-
the longitudinal study of adrenal maturation during gonadal suppression evidence that adrenarche is a gradual process
The Journal of Clinical Endocrinology and Metabolism, 2001Co-Authors: Mark R Palmert, Douglas Hayden, Joan M Mansfield, J F Crigler, William F Crowley, Donald W Chandler, Paul A BoeppleAbstract:The physical changes that herald the onset of puberty result from the combination of adrenarche and gonadarche. To examine adrenal maturation and associated changes in growth without the confounding effects of changes in the gonadal steroid milieu, we performed a longitudinal study in 14 young girls with idiopathic central precocious puberty during long-term pituitary-gonadal suppression. Beginning at the mean age of 2.9 yr, Dehydroepiandrosterone sulfate levels, linear growth, skeletal maturation, body mass index, and secondary sexual development were evaluated at 3- to 6-month intervals for up to 12.3 yr. In 12 of the girls, levels of Dehydroepiandrosterone, androstenedione, 17-hydroxypregnenolone, and 17α-hydroxyprogesterone were determined before and after acute ACTH stimulation every 6 months to investigate the maturation of adrenal steroidogenic enzyme activity. Serum Dehydroepiandrosterone sulfate levels rose progressively throughout the study. An exponential model fit the longitudinal datasets wel...
Hongkun Zhao - One of the best experts on this subject based on the ideXlab platform.
-
solubility determination and thermodynamic models for Dehydroepiandrosterone acetate in mixed solvents of ethyl acetate methanol ethyl acetate ethanol and ethyl acetate isopropanol
The Journal of Chemical Thermodynamics, 2016Co-Authors: Chao Cheng, Yang Cong, Jian Wang, Ganbing Yao, Hongkun ZhaoAbstract:Abstract The solubility of Dehydroepiandrosterone acetate in binary solvent mixtures of (ethyl acetate + methanol), (ethyl acetate + ethanol) and (ethyl acetate + isopropanol) was determined experimentally by using an isothermal dissolution equilibrium method within the temperature range from (273.15 to 313.15) K under atmosphere pressure (101.1 kPa). The solubility of Dehydroepiandrosterone acetate increases with increasing temperature and mass fraction of ethyl acetate in each binary system. At the same temperature and mass fraction of ethyl acetate, the solubility of Dehydroepiandrosterone acetate was greater in (ethyl acetate + isopropanol) than in the other two mixed solvents. The measured solubility values were correlated with the Jouyban-Acree model, van’t Hoff-Jouyban-Acree model, and modified Apelblat-Jouyban-Acree model. The Jouyban-Acree model was proven to give better representation for the experimental solubility, which provided the lowest relative average deviation and root-mean-square deviation (0.49 × 10 −2 and 0.97 × 10 −4 for ethyl acetate + methanol, 0.44 × 10 −2 and 0.82 × 10 −4 for ethyl acetate + ethanol, and 0.92 × 10 −2 and 3.05 × 10 −4 for ethyl acetate + isopropanol, respectively). Based on the solubility values obtained, the standard dissolution enthalpies for the dissolution process were computed. The dissolution process of Dehydroepiandrosterone acetate in these mixed solvents was endothermic. The experimental solubility and the equations presented in the present work can be employed as essential data and models in the practical process for production and purification of Dehydroepiandrosterone acetate.
-
solubility measurement and thermodynamic functions of Dehydroepiandrosterone acetate in different solvents at evaluated temperatures
The Journal of Chemical Thermodynamics, 2016Co-Authors: Chao Cheng, Yang Cong, Ganbing Yao, Long Meng, Jing Wang, Hongkun ZhaoAbstract:Abstract The solubility was measured for Dehydroepiandrosterone acetate in cyclohexane, acetone, ethyl acetate, acetonitrile, methanol, 1-butanol, ethanol and isopropanol by high-performance liquid chromatography analysis under the pressure of 101.3 kPa. The temperature of the determination varied from (273.15 K to 318.15) K. The Dehydroepiandrosterone acetate solubility increased with the increase in temperature, and obeyed the following order from high to low: ethyl acetate > acetone > 1-butanol > acetonitrile > (cyclohexane, isopropanol) > ethanol > methanol. They were correlated with four models, viz . the modified Apelblat equation, λh equation, Wilson model and NRTL model. The largest average standard deviation is 5.93 × 10 −4 , and the largest relative average deviation is 1.18% for each set of solubility values. The calculated solubility was in good agreement with the experimental values for the four models. Moreover, the thermodynamic properties of the solution process, including the apparent standard dissolution enthalpy and excess enthalpy were calculated. The experimental solubility, thermodynamic models and thermodynamic properties are very important in the purification process of Dehydroepiandrosterone acetate.
Paul A Boepple - One of the best experts on this subject based on the ideXlab platform.
-
the longitudinal study of adrenal maturation during gonadal suppression evidence that adrenarche is a gradual process
The Journal of Clinical Endocrinology and Metabolism, 2001Co-Authors: Mark R Palmert, Douglas Hayden, Joan M Mansfield, J F Crigler, William F Crowley, Donald W Chandler, Paul A BoeppleAbstract:The physical changes that herald the onset of puberty result from the combination of adrenarche and gonadarche. To examine adrenal maturation and associated changes in growth without the confounding effects of changes in the gonadal steroid milieu, we performed a longitudinal study in 14 young girls with idiopathic central precocious puberty during long-term pituitary-gonadal suppression. Beginning at the mean age of 2.9 yr, Dehydroepiandrosterone sulfate levels, linear growth, skeletal maturation, body mass index, and secondary sexual development were evaluated at 3- to 6-month intervals for up to 12.3 yr. In 12 of the girls, levels of Dehydroepiandrosterone, androstenedione, 17-hydroxypregnenolone, and 17alpha-hydroxyprogesterone were determined before and after acute ACTH stimulation every 6 months to investigate the maturation of adrenal steroidogenic enzyme activity. Serum Dehydroepiandrosterone sulfate levels rose progressively throughout the study. An exponential model fit the longitudinal datasets well and indicated that Dehydroepiandrosterone sulfate levels increased approximately 22%/yr from the youngest age onward. Increasing activity of 17-20 lyase (CYP17) and decreasing activity of 3beta-hydroxysteroid dehydrogenase were also evident in preadrenarchal subjects. When controlled for chronological age, no significant associations were noted between weight, body mass index, or body surface area and Dehydroepiandrosterone sulfate levels. However, similar analyses revealed modest correlations of both height and growth velocity with Dehydroepiandrosterone sulfate levels. Our results suggest that adrenarche is not the result of sudden rapid changes in adrenal enzyme activities or adrenal androgen concentrations; rather, adrenarche may be a gradual maturational process that begins in early childhood.
-
the longitudinal study of adrenal maturation during gonadal suppression evidence that adrenarche is a gradual process
The Journal of Clinical Endocrinology and Metabolism, 2001Co-Authors: Mark R Palmert, Douglas Hayden, Joan M Mansfield, J F Crigler, William F Crowley, Donald W Chandler, Paul A BoeppleAbstract:The physical changes that herald the onset of puberty result from the combination of adrenarche and gonadarche. To examine adrenal maturation and associated changes in growth without the confounding effects of changes in the gonadal steroid milieu, we performed a longitudinal study in 14 young girls with idiopathic central precocious puberty during long-term pituitary-gonadal suppression. Beginning at the mean age of 2.9 yr, Dehydroepiandrosterone sulfate levels, linear growth, skeletal maturation, body mass index, and secondary sexual development were evaluated at 3- to 6-month intervals for up to 12.3 yr. In 12 of the girls, levels of Dehydroepiandrosterone, androstenedione, 17-hydroxypregnenolone, and 17α-hydroxyprogesterone were determined before and after acute ACTH stimulation every 6 months to investigate the maturation of adrenal steroidogenic enzyme activity. Serum Dehydroepiandrosterone sulfate levels rose progressively throughout the study. An exponential model fit the longitudinal datasets wel...