8 research outputs found
Detection of xenoestrogens in serum after immunoprecipitation of endogenous steroidal estrogens.
In this article we report a simple and efficient method for detecting nonsteroidal estrogens in a biologic sample. This method uses polyclonal antibodies to estradiol (E2) to immunoprecipitate these major biologically active steroidal estrogens, leaving behind the nonsteroidal estrogens, which are then detected in a cell-based transcriptional activation bioassay for estrogen receptor agonist. The immunoprecipitation method efficiently removed 99% of radiolabeled E2 and estrone (E1) from human serum. In experiments in which supraphysiologic concentrations of E2 and E1 to human serum, all of the immunoreactive estrogens were still removed by the immunoprecipitation protocol. We carried out an in vivo validation study of this method in which we treated female macaques with the xenoestrogen nonylphenol (NP), during the late follicular phase of the menstrual cycle. We used blood samples collected before and after treatment to evaluate and characterize endogenous and exogenous serum estrogens. An immunoassay for E2 did not detect the NP in treated monkeys. The cell-based bioassay also did not detect the estrogenic activity of NP because of its saturation by the endogenous serum steroidal estrogens. However, when steroidal estrogens were removed by immunoprecipitation, we detected the estrogenic activity of NP in the bioassay. Thus, this approach is appropriate for detecting exogenous, nonsteroidal estrogens in serum samples
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Detection of xenoestrogens in serum after immunoprecipitation of endogenous steroidal estrogens.
In this article we report a simple and efficient method for detecting nonsteroidal estrogens in a biologic sample. This method uses polyclonal antibodies to estradiol (E2) to immunoprecipitate these major biologically active steroidal estrogens, leaving behind the nonsteroidal estrogens, which are then detected in a cell-based transcriptional activation bioassay for estrogen receptor agonist. The immunoprecipitation method efficiently removed 99% of radiolabeled E2 and estrone (E1) from human serum. In experiments in which supraphysiologic concentrations of E2 and E1 to human serum, all of the immunoreactive estrogens were still removed by the immunoprecipitation protocol. We carried out an in vivo validation study of this method in which we treated female macaques with the xenoestrogen nonylphenol (NP), during the late follicular phase of the menstrual cycle. We used blood samples collected before and after treatment to evaluate and characterize endogenous and exogenous serum estrogens. An immunoassay for E2 did not detect the NP in treated monkeys. The cell-based bioassay also did not detect the estrogenic activity of NP because of its saturation by the endogenous serum steroidal estrogens. However, when steroidal estrogens were removed by immunoprecipitation, we detected the estrogenic activity of NP in the bioassay. Thus, this approach is appropriate for detecting exogenous, nonsteroidal estrogens in serum samples
From Molecular Dehydration to Excess Volumes of Phase-Separating PNIPAM Solutions
For aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions, a
structural instability leads to the collapse and aggregation of the macromolecules at the
temperature-induced demixing transition. The accompanying cooperative dehydration of
the PNIPAM chains is known to play a crucial role in this phase separation. We elucidate
the impact of partial dehydration of PNIPAM on the volume changes related to the phase
separation of dilute to concentrated PNIPAM solutions. Quasi-elastic neutron scattering
enables us to directly follow the isotropic jump diffusion behavior of the hydration water
and the almost freely diffusing water. As the hydration number decreases from 8 to 2 for
the demixing 25 mass % PNIPAM solution, only a partial dehydration of the PNIPAM
chains occurs. Dilatation studies reveal that the transition-induced volume changes
depend in a remarkable manner on the PNIPAM concentration of the solutions. The
excess volume per mole of H2O molecules expelled from the solvation layers of PNIPAM
during phase separation probably strongly increases from dilute to concentrated PNIPAM
solutions. This finding is qualitatively related to the immense strain-softening previously observed for demixing PNIPAM
solutions
Nanoconfined libh4 and enhanced mobility of li+ and bh4- studied by solid-state nmr
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