The Experts below are selected from a list of 7869 Experts worldwide ranked by ideXlab platform
Tamas Zakar - One of the best experts on this subject based on the ideXlab platform.
-
Expression and Localization in Guinea Pig Gestational Tissues During Late Pregnancy and Parturition
2016Co-Authors: Toni Welsh, Sam Mesiano, Hannah K Palliser, Hessam Tabatabaee, Jonathan Paul, Jonathan Hirst, Tamas ZakarAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDHmRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor
-
15 hydroxyprostaglandin dehydrogenase expression and localization in guinea pig gestational tissues during late pregnancy and parturition
Reproductive Sciences, 2012Co-Authors: Toni Welsh, Sam Mesiano, Jonathan J Hirst, Tamas Zakar, Jonathan W Paul, Hannah K Palliser, Hessam TabatabaeeAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDH mRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor.
-
Nuclear Progesterone Receptor Expression in the Human Fetal Membranes and Decidua at Term Before and After Labor
Reproductive Sciences, 2009Co-Authors: Amy Merlino, Toni Welsh, Tamas Zakar, Tan Erdonmez, Gemma Madsen, Roger Smith, Brian Mercer, Sam MesianoAbstract:To explore how progesterone affects human pregnancy, we identified the progesterone target cells within thefetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion–decidua) were obtained after term cesarean deliveries performed before (n = 7) and after (n = 7) Labor Onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase–polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion–decidua and did not change in association with Labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor–mediated progesterone actions during human pregnancy.
-
prostaglandin endoperoxide h synthase 1 and 2 messenger ribonucleic acid levels in human amnion with spontaneous Labor Onset
The Journal of Clinical Endocrinology and Metabolism, 1995Co-Authors: Jonathan J Hirst, F J Teixeira, Tamas Zakar, David M OlsonAbstract:Increased prostaglandin (PG) production within the uterine compartment has a pivotal role in the processes leading to Labor Onset in women. Two PG endoperoxide-H synthase (PGHS) isoenzymes have been identified in a number of cell types. PGHS-1 is constitutively expressed in most cases, whereas PGHS-2 expression is rapidly induced by several agonists. The aims of this study were to determine the levels of PGHS-1 and PGHS-2 expression before and after spontaneous Labor (SL) Onset in the amnion and to assess the contribution of PGHS-1 and PGHS-2 to enzyme activity. We established and validated ribonuclease protection assays to quantify PGHS-1 and PGHS-2 messenger ribonucleic acid (mRNA) levels in the amnion. PGHS enzyme activity was measured with an established assay. The antisense RNA probes used in the protection assays were generated using human PGHS-1 and PGHS-2 complementary DNAs. These probes specifically detected the 2.8-kilobase mRNA of PGHS-1 and the 4.8-kilobase mRNA of PGHS-2 in amnion RNA samples...
-
prostaglandin endoperoxide h synthase pghs activity and immunoreactive pghs 1 and pghs 2 levels in human amnion throughout gestation at term and during Labor
The Journal of Clinical Endocrinology and Metabolism, 1994Co-Authors: F J Teixeira, Jonathan J Hirst, Tamas Zakar, Fang Guo, D W Sadowsky, G Machin, Nestor Demianczuk, B Resch, David M OlsonAbstract:Prostaglandins (PGs) are of primary importance in the initiation and maintenance of Labor in women. A major intrauterine source of prostaglandins is the amnion, which synthesizes increased amounts of PGE2 at term Labor. Because PG endoperoxide-H synthase (PGHS) catalyzes the rate-limiting step of PG synthesis from arachidonic acid, we investigated the changes in amniotic PGHS specific activity during gestation and at term and preterm Labor. Also, we determined the level of immunoreactive PGHS protein in the amnion to evaluate the mechanisms by which PGHS activity may be regulated. PGHS specific activity, measured at the amount of PGE2 produced by amnion microsomes under optimal conditions, was 18.2 +/- 3.7 pg PGE2/micrograms protein.min (mean +/- SE; n = 19) at term (37-42 weeks gestation) before the spontaneous Onset of Labor. PGHS specific activity was significantly higher after spontaneous term Labor (38.9 +/- 6.0 pg PGE2/micrograms protein.min; n = 19; P < 0.05). Amnion samples from preterm (< 36 weeks gestation) nonLaboring patients contained low levels of PGHS specific activity (5.9 +/- 1.8 pg PGE2/micrograms protein.min; n = 9), which increased significantly with spontaneous preterm Labor (28.3 +/- 6.8 pg PGE2/micrograms protein.min; n = 10; P < 0.05). Longitudinal analysis of the data showed that PGHS specific activity was low in the first and second trimesters of gestation, but increased dramatically before Labor Onset at term. We detected PGHS protein in all microsomal samples, with an antiovine PGHS antibody recognizing both PGHS-1 and -2 isoforms of the enzyme. However, there was no correlation between PGHS specific activity and the amount of immunoreactive PGHS protein. Using an antibody specific for PGHS-2, we detected immunoreactive protein in only 9 of the 25 tissues examined and found no correlation between PGHS specific activity and the amount of PGHS-2 protein. These results suggest that 1) PGHS specific activity in the amnion increases sharply before the Onset of Labor at term; 2) further increases in specific activity occur during term and preterm Labor; and 3) the specific activity of PGHS in the amnion is not related directly to the amount of immunoreactive enzyme protein.
Sam Mesiano - One of the best experts on this subject based on the ideXlab platform.
-
Expression and Localization in Guinea Pig Gestational Tissues During Late Pregnancy and Parturition
2016Co-Authors: Toni Welsh, Sam Mesiano, Hannah K Palliser, Hessam Tabatabaee, Jonathan Paul, Jonathan Hirst, Tamas ZakarAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDHmRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor
-
Mesiano S: Nuclear progesterone receptor expression in the human fetal membranes and decidua at term before and after Labor. Reprod Sci 2009
2016Co-Authors: Amy Merlino, Toni Welsh, Tan Erdonmez, Brian Mercer, Sam MesianoAbstract:To explore how progesterone affects human pregnancy, we identified the progesterone target cells within the fetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion–decidua) were obtained after term cesarean deliveries performed before (n 7) and after (n 7) Labor Onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase–polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion–decidua and did not change in association with Labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor–mediated progesterone actions during human pregnancy. KEY WORDS: Progesterone receptors, fetal membranes, human parturition
-
15 hydroxyprostaglandin dehydrogenase expression and localization in guinea pig gestational tissues during late pregnancy and parturition
Reproductive Sciences, 2012Co-Authors: Toni Welsh, Sam Mesiano, Jonathan J Hirst, Tamas Zakar, Jonathan W Paul, Hannah K Palliser, Hessam TabatabaeeAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDH mRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor.
-
Nuclear Progesterone Receptor Expression in the Human Fetal Membranes and Decidua at Term Before and After Labor
Reproductive Sciences, 2009Co-Authors: Amy Merlino, Toni Welsh, Tamas Zakar, Tan Erdonmez, Gemma Madsen, Roger Smith, Brian Mercer, Sam MesianoAbstract:To explore how progesterone affects human pregnancy, we identified the progesterone target cells within thefetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion–decidua) were obtained after term cesarean deliveries performed before (n = 7) and after (n = 7) Labor Onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase–polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion–decidua and did not change in association with Labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor–mediated progesterone actions during human pregnancy.
-
nuclear progesterone receptors in the human pregnancy myometrium evidence that parturition involves functional progesterone withdrawal mediated by increased expression of progesterone receptor a
The Journal of Clinical Endocrinology and Metabolism, 2007Co-Authors: Amy Merlino, Toni Welsh, Li Juan Yi, Vernon Cannon, Brian M Mercer, Sam MesianoAbstract:Context: We examined whether human parturition involves functional progesterone withdrawal mediated by changes in myometrial expression of progesterone receptors (PRs)-A and -B. Objective: Our objectives were to: 1) measure PR-A and PR-B protein levels in human pregnancy myometrium and determine whether the PR-A to PR-B ratio changes with advancing gestation and Labor Onset; and 2) determine how changes in the PR-A to PR-B ratio affect myometrial cell progesterone responsiveness. Design: PR protein levels and cellular localization were measured by Western blotting and immunohistochemistry, respectively, in lower uterine segment uterine wall tissue from preterm (<37 wk; not Laboring; n = 5) and term (37–40 wk; not in Labor: n = 6; in Labor: n = 5) cesarean delivery. The capacity for PR-A and PR-B, alone and in combination, to mediate genomic progesterone responsiveness measured by the activity of a progesterone-responsive reporter plasmid was examined by artificially modulating their levels in the PHM1–31 ...
Toni Welsh - One of the best experts on this subject based on the ideXlab platform.
-
Expression and Localization in Guinea Pig Gestational Tissues During Late Pregnancy and Parturition
2016Co-Authors: Toni Welsh, Sam Mesiano, Hannah K Palliser, Hessam Tabatabaee, Jonathan Paul, Jonathan Hirst, Tamas ZakarAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDHmRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor
-
Mesiano S: Nuclear progesterone receptor expression in the human fetal membranes and decidua at term before and after Labor. Reprod Sci 2009
2016Co-Authors: Amy Merlino, Toni Welsh, Tan Erdonmez, Brian Mercer, Sam MesianoAbstract:To explore how progesterone affects human pregnancy, we identified the progesterone target cells within the fetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion–decidua) were obtained after term cesarean deliveries performed before (n 7) and after (n 7) Labor Onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase–polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion–decidua and did not change in association with Labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor–mediated progesterone actions during human pregnancy. KEY WORDS: Progesterone receptors, fetal membranes, human parturition
-
15 hydroxyprostaglandin dehydrogenase expression and localization in guinea pig gestational tissues during late pregnancy and parturition
Reproductive Sciences, 2012Co-Authors: Toni Welsh, Sam Mesiano, Jonathan J Hirst, Tamas Zakar, Jonathan W Paul, Hannah K Palliser, Hessam TabatabaeeAbstract:Prostaglandins are key components of the parturition cascade; however, the mechanisms that regulate prostaglandin concentrations in the uterus during pregnancy are largely unknown. The purpose of this study was to determine the intrauterine expression of the chief prostaglandin-inactivating enzyme, 15-hydroxyprostaglandin dehydrogenase (PGDH), during gestation and Labor in the guinea pig, an animal model in which the endocrine control of pregnancy and parturition is analogous to that of women. PGDH messenger RNA (mRNA) abundance decreased significantly in the visceral yolk sac membrane (VYS, the anatomical equivalent of the human chorion laeve) and the amnion throughout the last third of pregnancy. PGDH protein was robustly expressed in the VYS epithelium and mesoderm, correlated strongly with PGDH mRNA levels and exhibited a nadir at term prior to Labor Onset. PGDH protein was not detected in the amnion. PGDH mRNA and protein levels in the placenta and myoendometrium were variable throughout late gestation. In the placenta, PGDH protein was concentrated in the parietal yolk sac membrane (PYS) lining the placental surface and in placental blood vessels. We observed strong expression of PGDH protein in the endometrial epithelium with comparably little expression in the myometrium. These data indicate that metabolic inactivation of prostaglandins in the pregnant guinea pig uterus takes place in the VYS, PYS, and endometrium. Decreased PGDH expression in the fetal membranes may contribute to the increase in intrauterine prostaglandin concentrations at term, stimulating the Onset of Labor.
-
Nuclear Progesterone Receptor Expression in the Human Fetal Membranes and Decidua at Term Before and After Labor
Reproductive Sciences, 2009Co-Authors: Amy Merlino, Toni Welsh, Tamas Zakar, Tan Erdonmez, Gemma Madsen, Roger Smith, Brian Mercer, Sam MesianoAbstract:To explore how progesterone affects human pregnancy, we identified the progesterone target cells within thefetal membranes (amnion, chorion, and decidua) at term by assessing the extent of expression and localization of the nuclear progesterone receptors, progesterone receptor-A and progesterone receptor-B. Fetal membranes (separated into amnion and chorion–decidua) were obtained after term cesarean deliveries performed before (n = 7) and after (n = 7) Labor Onset. Nuclear progesterone receptor expression was determined by the abundance of nuclear progesterone receptor mRNAs (by quantitative reverse transcriptase–polymerase chain reaction) and proteins (by western blotting). Localization of nPRs was determined by immunohistochemistry. Progesterone receptor-A and progesterone receptor-B mRNA and protein levels were highest in the chorion–decidua and did not change in association with Labor. Nuclear progesterone receptor mRNAs and proteins were barely detectable in amnion. Nuclear progesterone receptor immunostaining was detected only in the nucleus of decidual cells. These findings suggest that the decidua, and not the amnion and chorion, is a direct target for nuclear progesterone receptor–mediated progesterone actions during human pregnancy.
-
nuclear progesterone receptors in the human pregnancy myometrium evidence that parturition involves functional progesterone withdrawal mediated by increased expression of progesterone receptor a
The Journal of Clinical Endocrinology and Metabolism, 2007Co-Authors: Amy Merlino, Toni Welsh, Li Juan Yi, Vernon Cannon, Brian M Mercer, Sam MesianoAbstract:Context: We examined whether human parturition involves functional progesterone withdrawal mediated by changes in myometrial expression of progesterone receptors (PRs)-A and -B. Objective: Our objectives were to: 1) measure PR-A and PR-B protein levels in human pregnancy myometrium and determine whether the PR-A to PR-B ratio changes with advancing gestation and Labor Onset; and 2) determine how changes in the PR-A to PR-B ratio affect myometrial cell progesterone responsiveness. Design: PR protein levels and cellular localization were measured by Western blotting and immunohistochemistry, respectively, in lower uterine segment uterine wall tissue from preterm (<37 wk; not Laboring; n = 5) and term (37–40 wk; not in Labor: n = 6; in Labor: n = 5) cesarean delivery. The capacity for PR-A and PR-B, alone and in combination, to mediate genomic progesterone responsiveness measured by the activity of a progesterone-responsive reporter plasmid was examined by artificially modulating their levels in the PHM1–31 ...
David M Olson - One of the best experts on this subject based on the ideXlab platform.
-
interleukin 6 is an essential determinant of on time parturition in the mouse
Endocrinology, 2010Co-Authors: Sarah A Robertson, Inge Christiaens, Camilla Dorian, Dean B Zaragoza, Alison S Care, Anke M Banks, David M OlsonAbstract:IL-6 abundance in amniotic fluid and uterine tissues increases in late gestation or with infection-associated preterm Labor. A role in regulation of Labor Onset is suggested by observations that IL-6 increases expression of genes controlling prostaglandin synthesis and signaling in isolated uterine cells, but whether IL-6 is essential for normal parturition is unknown. To evaluate the physiological role of IL-6 in parturition in mice, we investigated the effect of Il6 null mutation on the timing of parturition and expression of genes associated with uterine activation. Il6 null mutant mice delivered 24 h later than wild-type mice, although circulating progesterone fell similarly in both genotypes during the prepartal period. Il6 null mutant mice were also refractory to low doses of lipopolysaccharide sufficient to induce preterm delivery in wild-type mice. The characteristic late-gestation elevation in uterine expression of Oxtr mRNA encoding oxytocin receptor, and peripartal increases in Ptgfr and Ptgs2 ...
-
prostaglandin endoperoxide h synthase 1 and 2 messenger ribonucleic acid levels in human amnion with spontaneous Labor Onset
The Journal of Clinical Endocrinology and Metabolism, 1995Co-Authors: Jonathan J Hirst, F J Teixeira, Tamas Zakar, David M OlsonAbstract:Increased prostaglandin (PG) production within the uterine compartment has a pivotal role in the processes leading to Labor Onset in women. Two PG endoperoxide-H synthase (PGHS) isoenzymes have been identified in a number of cell types. PGHS-1 is constitutively expressed in most cases, whereas PGHS-2 expression is rapidly induced by several agonists. The aims of this study were to determine the levels of PGHS-1 and PGHS-2 expression before and after spontaneous Labor (SL) Onset in the amnion and to assess the contribution of PGHS-1 and PGHS-2 to enzyme activity. We established and validated ribonuclease protection assays to quantify PGHS-1 and PGHS-2 messenger ribonucleic acid (mRNA) levels in the amnion. PGHS enzyme activity was measured with an established assay. The antisense RNA probes used in the protection assays were generated using human PGHS-1 and PGHS-2 complementary DNAs. These probes specifically detected the 2.8-kilobase mRNA of PGHS-1 and the 4.8-kilobase mRNA of PGHS-2 in amnion RNA samples...
-
prostaglandin endoperoxide h synthase pghs activity and immunoreactive pghs 1 and pghs 2 levels in human amnion throughout gestation at term and during Labor
The Journal of Clinical Endocrinology and Metabolism, 1994Co-Authors: F J Teixeira, Jonathan J Hirst, Tamas Zakar, Fang Guo, D W Sadowsky, G Machin, Nestor Demianczuk, B Resch, David M OlsonAbstract:Prostaglandins (PGs) are of primary importance in the initiation and maintenance of Labor in women. A major intrauterine source of prostaglandins is the amnion, which synthesizes increased amounts of PGE2 at term Labor. Because PG endoperoxide-H synthase (PGHS) catalyzes the rate-limiting step of PG synthesis from arachidonic acid, we investigated the changes in amniotic PGHS specific activity during gestation and at term and preterm Labor. Also, we determined the level of immunoreactive PGHS protein in the amnion to evaluate the mechanisms by which PGHS activity may be regulated. PGHS specific activity, measured at the amount of PGE2 produced by amnion microsomes under optimal conditions, was 18.2 +/- 3.7 pg PGE2/micrograms protein.min (mean +/- SE; n = 19) at term (37-42 weeks gestation) before the spontaneous Onset of Labor. PGHS specific activity was significantly higher after spontaneous term Labor (38.9 +/- 6.0 pg PGE2/micrograms protein.min; n = 19; P < 0.05). Amnion samples from preterm (< 36 weeks gestation) nonLaboring patients contained low levels of PGHS specific activity (5.9 +/- 1.8 pg PGE2/micrograms protein.min; n = 9), which increased significantly with spontaneous preterm Labor (28.3 +/- 6.8 pg PGE2/micrograms protein.min; n = 10; P < 0.05). Longitudinal analysis of the data showed that PGHS specific activity was low in the first and second trimesters of gestation, but increased dramatically before Labor Onset at term. We detected PGHS protein in all microsomal samples, with an antiovine PGHS antibody recognizing both PGHS-1 and -2 isoforms of the enzyme. However, there was no correlation between PGHS specific activity and the amount of immunoreactive PGHS protein. Using an antibody specific for PGHS-2, we detected immunoreactive protein in only 9 of the 25 tissues examined and found no correlation between PGHS specific activity and the amount of PGHS-2 protein. These results suggest that 1) PGHS specific activity in the amnion increases sharply before the Onset of Labor at term; 2) further increases in specific activity occur during term and preterm Labor; and 3) the specific activity of PGHS in the amnion is not related directly to the amount of immunoreactive enzyme protein.
Mary E. D'alton - One of the best experts on this subject based on the ideXlab platform.
-
Cesarean delivery in the United States 2005 through 2014: a population-based analysis using the Robson 10-Group Classification System.
American Journal of Obstetrics and Gynecology, 2018Co-Authors: Mark P. Hehir, Cande V. Ananth, Zainab Siddiq, Karen Flood, Alexander M. Friedman, Mary E. D'altonAbstract:Background Cesarean delivery has increased steadily in the United States over recent decades with significant downstream health consequences. The World Health Organization has endorsed the Robson 10-Group Classification System as a global standard to facilitate analysis and comparison of cesarean delivery rates. Objective Our objective was to apply the Robson 10-Group Classification System to a nationwide cohort in the United States over a 10-year period. Study Design This population-based analysis applied the Robson 10-Group Classification System to all births in the United States from 2005 through 2014, recorded in the 2003 revised birth certificate format. Over the study 10-year period, 27,044,217 deliveries met inclusion criteria. Five parameters (parity including previous cesarean, gestational age, Labor Onset, fetal presentation, and plurality), identifiable on presentation for delivery, were used to classify all women included into 1 of 10 groups. Results The overall cesarean rate was 31.6%. Group-3 births (singleton, term, cephalic multiparas in spontaneous Labor) were most common, while group-5 births (those with a previous cesarean) accounted for the most cesarean deliveries increasing from 27% of all cesareans in 2005 through 2006 to >34% in 2013 through 2014. Breech pregnancies (groups 6 and 7) had cesarean rates >90%. Primiparous and multiparous women who had a preLabor cesarean (groups 2b and 4b) accounted for over one quarter of all cesarean deliveries. Conclusion Women with a previous cesarean delivery represent an increasing proportion of cesarean deliveries. Use of the Robson criteria allows standardized comparisons of data and identifies clinical scenarios driving changes in cesarean rates. Hospitals and health organizations can use the Robson 10-Group Classification System to evaluate quality and processes associated with cesarean delivery.
