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Alterations of human placental epidermal growth factor receptor in intrauterine growth retardation
A.22
Placenta (1993), Vol 14
METABOLISM AND TRANSFER OF THE ENANTIOMERS OF PROPRANOLOL IN THE ISOLATED PERFUSED HUMAN PLACENTAL LOBULE. Anthony Fletcherta, David Maguire2, Les Johnson3, Robin Mortimert~ and Graeme Carmell t. ~Conjoint Endocrine Laboratory, Royal Brisbane Hospital; ZFaculty of Science and Technology, Grfffith University; ~Dept of Pathology, Royal Brisbane Hospital, and 4Dept of Obstetrics and Gynaecology, University of Queensland; Brisbane, Australia. The S-(-)-enantiomer of propranolol (PPL) has a physiological action about a hundred fold greater than the R-(+)--enantiomer as a nonselective beta adrenergic blocking agent (1). The concentration of PPL in plasma varies widely in individuals following oral doses (2), the disposition is dose dependent and affected by factors such as age or hepatic disease. PPL enantiomers are metabolised at differing rates by human and dog hepatic microsomes with variability between product ratios and between individuals (2). To investigate PPL metabolism by the human placenta, PPL was perfused in the dual recirculating human placental lobule with maternal dosing in two sets of experiments at 150 ng/ml (n = 4) and 1.5 ~g/ml (n ffi 5). Six hour peffusate samples from the maternal and foetal circulations were analysed and one metabolite, des(isopropylamino)-propranolol, was identified by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). No 4-hydroxypropranolol or other metabolites were detected. For chiral analysis, samples containing pronethalol as internal standard were extracted using reversed phase cartridges and derivatised with R-(+)--1-phenylethyl isocyanate in dichloromethane for 35 minutes. The samples were analysed by HPLC (C~s column maintained at 40"C with a mobile phase of methanol:water:acetic acid 70:30:0.1 at 1.2 ml/min) using fluorescence detection (ex. 295 nm, era. 345 nm). Maternal and foetal samples were examined after six hours peffusion at both substrate concentrations for the relative enantiomer composition (ratio of R to S enantiomer) of propranolol. The low concentration (mean • S.D.; maternal 0.96 • 0.09, foetal 0.98 • 0.11) and high (maternal 0.94 • 0.11, foetal 0.94 • 0.1) ratios were not significantly different and neither of these sets of results was significantly different from an analysis of racemic propranol (n = 3, 1.06 • 0.053) used for these experiments. Propranolol is not subject to assymetric metabolism in the human placenta after six hour perfusions. 1 Barrett, A. M., (1968) Br J Pharmacol 34, 43. 2 Von Bahr, C., (1982) J Pharmacol Exp Ther 222, 458-462.
ALTERATIONS OF HUMAN PLACENTAL EPIDERMAL GROWTH FACTOR RECEPTOR IN INTRAUTERINE GROWTH RETARDATION. C. Fondacci, E. Alsat, C. Nessman and D. Evain-Brion, Physiopathologie du ddveloppement, CNRS-ENS, 46 rue d'Ulm,75230 Paris, France and Biologie du d6veloppement et de la reproduction, h6pital R. Debr6, 75019 Paris, France. We studied human placental microvillous epidermal growth factor receptor (EGFR) and its relationship with maternal and placental features in 12 cases of intrauterine growth retardation (IUGR)). Placental EGFR phosphorylation was significantly decreased or absent in 10 cases of small for gestational age (SGA) neonates, as shown by SDS-PAGE, autoradiography and scanning analysis. Specific 125I-EGF binding and Scatchard plots of the binding data showed a decreased number of EGFR in six of the 10 cases, with a mean Bmax of 1.09 + 0.32 pmol/mg for high affinity sites (mean control value: 2.30 + 0.23 pmol/mg). Most of the hypertensive women and smokers belonged to this subgroup. In the four remaining cases of SGA placentas with low EGFR phosphorylation, there was no maternal pathology or significant parenchymatous placental lesions. Three showed a 175 kDa EGFR species when probed by 125I-EGF cross-linking and Western blotting with RK2 and Ct, two polyclonal anti-EGFR antibodies, suggesting abnormal transduction of the EGF-induced signal. The fourth placenta yielded a single 145 kDa EGFR band consistent with an abnormal EGFR structure; Western blot analysis showed no immunoreactive band. In conclusion, maternal and placental pathologies in IUGR are associated with various alterations of placental EGFR, pointing out the importance of EGFR ligands in the regulatory pathway of placental and fetalm growth.
Placenta (1993), Vol 14
METABOLISM AND TRANSFER OF THE ENANTIOMERS OF PROPRANOLOL IN THE ISOLATED PERFUSED HUMAN PLACENTAL LOBULE. Anthony Fletcherta, David Maguire2, Les Johnson3, Robin Mortimert~ and Graeme Carmell t. ~Conjoint Endocrine Laboratory, Royal Brisbane Hospital; ZFaculty of Science and Technology, Grfffith University; ~Dept of Pathology, Royal Brisbane Hospital, and 4Dept of Obstetrics and Gynaecology, University of Queensland; Brisbane, Australia. The S-(-)-enantiomer of propranolol (PPL) has a physiological action about a hundred fold greater than the R-(+)--enantiomer as a nonselective beta adrenergic blocking agent (1). The concentration of PPL in plasma varies widely in individuals following oral doses (2), the disposition is dose dependent and affected by factors such as age or hepatic disease. PPL enantiomers are metabolised at differing rates by human and dog hepatic microsomes with variability between product ratios and between individuals (2). To investigate PPL metabolism by the human placenta, PPL was perfused in the dual recirculating human placental lobule with maternal dosing in two sets of experiments at 150 ng/ml (n = 4) and 1.5 ~g/ml (n ffi 5). Six hour peffusate samples from the maternal and foetal circulations were analysed and one metabolite, des(isopropylamino)-propranolol, was identified by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). No 4-hydroxypropranolol or other metabolites were detected. For chiral analysis, samples containing pronethalol as internal standard were extracted using reversed phase cartridges and derivatised with R-(+)--1-phenylethyl isocyanate in dichloromethane for 35 minutes. The samples were analysed by HPLC (C~s column maintained at 40"C with a mobile phase of methanol:water:acetic acid 70:30:0.1 at 1.2 ml/min) using fluorescence detection (ex. 295 nm, era. 345 nm). Maternal and foetal samples were examined after six hours peffusion at both substrate concentrations for the relative enantiomer composition (ratio of R to S enantiomer) of propranolol. The low concentration (mean • S.D.; maternal 0.96 • 0.09, foetal 0.98 • 0.11) and high (maternal 0.94 • 0.11, foetal 0.94 • 0.1) ratios were not significantly different and neither of these sets of results was significantly different from an analysis of racemic propranol (n = 3, 1.06 • 0.053) used for these experiments. Propranolol is not subject to assymetric metabolism in the human placenta after six hour perfusions. 1 Barrett, A. M., (1968) Br J Pharmacol 34, 43. 2 Von Bahr, C., (1982) J Pharmacol Exp Ther 222, 458-462.
ALTERATIONS OF HUMAN PLACENTAL EPIDERMAL GROWTH FACTOR RECEPTOR IN INTRAUTERINE GROWTH RETARDATION. C. Fondacci, E. Alsat, C. Nessman and D. Evain-Brion, Physiopathologie du ddveloppement, CNRS-ENS, 46 rue d'Ulm,75230 Paris, France and Biologie du d6veloppement et de la reproduction, h6pital R. Debr6, 75019 Paris, France. We studied human placental microvillous epidermal growth factor receptor (EGFR) and its relationship with maternal and placental features in 12 cases of intrauterine growth retardation (IUGR)). Placental EGFR phosphorylation was significantly decreased or absent in 10 cases of small for gestational age (SGA) neonates, as shown by SDS-PAGE, autoradiography and scanning analysis. Specific 125I-EGF binding and Scatchard plots of the binding data showed a decreased number of EGFR in six of the 10 cases, with a mean Bmax of 1.09 + 0.32 pmol/mg for high affinity sites (mean control value: 2.30 + 0.23 pmol/mg). Most of the hypertensive women and smokers belonged to this subgroup. In the four remaining cases of SGA placentas with low EGFR phosphorylation, there was no maternal pathology or significant parenchymatous placental lesions. Three showed a 175 kDa EGFR species when probed by 125I-EGF cross-linking and Western blotting with RK2 and Ct, two polyclonal anti-EGFR antibodies, suggesting abnormal transduction of the EGF-induced signal. The fourth placenta yielded a single 145 kDa EGFR band consistent with an abnormal EGFR structure; Western blot analysis showed no immunoreactive band. In conclusion, maternal and placental pathologies in IUGR are associated with various alterations of placental EGFR, pointing out the importance of EGFR ligands in the regulatory pathway of placental and fetalm growth.