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G E Rice

Publications and source records attributed to G E Rice.

At least 73 records · Page 4Linked to original sources
PubMed1996

Differential release of interleukin-6 from human gestational tissues in association with labour and in vitro endotoxin treatment.

In this study, we quantified interleukin-6 (IL-6) concentrations in amniotic fluid at term and preterm labour, and determined the gestational tissue source of IL-6. In addition, aspects of the regulatory mechanisms involved in IL-6 release at the time of term labour and in response to bacterial endotoxin, lipopolysaccharide (LPS), have been established. IL-6 concentrations were 2-fold higher in amniotic fluid collected at term compared with preterm gestation, with an additional 2-fold increase in association with term labour. IL-6 was released from all choriodecidual and placental explants but was detected in only 33% of amniotic explant cultures of tissues obtained before labour onset. In contrast, IL-6 was detected in all amniotic, choriodecidual and placental cultures of tissues obtained after term labour onset and delivery, and the mean IL-6 release was significantly higher than that measured in explant cultures of both amniotic (80-fold increase, P < 0.0001) and choriodecidual (3-fold increase, P < 0.02) but not placental explants taken at the time of elective Caesarean section at term before labour onset. LPS significantly (P < 0.05) increased the release of IL-6 from human choriodecidual and placental explants but not amniotic explants, in a time- and dose-dependent manner. IL-6 is a physiological constituent of amniotic fluid and its production by gestational tissues is differentially regulated by LPS and spontaneous labour onset and delivery.

Amniotic Fluid↗
PubMed1996

Labour-associated increase in interleukin-1 alpha release in vitro by human gestational tissues.

The aims of this study were to investigate the concentration and release of interleukin-1 alpha (IL-1 alpha) at the time of human term labour, and to study the regulation of IL-1 alpha release from human gestational tissue explants by bacterial endotoxin. Immunoreactive IL-1 alpha concentrations in maternal plasma, amniotic fluid and conditioned media from human amniotic fluid and conditioned media from human amniotic, choriodecidual and placental explants were quantified before and after spontaneous term labour-onset and delivery. Furthermore, the effects of a bacterial endotoxin, lipopolysaccharide (LPS), on the release of IL-1 alpha from human gestational tissue explants over a time course of 24 h (n = 3) and LPS concentrations ranging from 10-10(7) pg/ml (n = 3) were investigated. IL-1 alpha concentrations in maternal plasma and amniotic fluid did not change significantly with spontaneous term labour-onset. In contrast, IL-1 alpha was released in detectable amounts from human amniotic and choriodecidual explants only in association with term labour-onset and delivery. Similarly, placental release of IL-1 alpha was increased significantly in explant cultures in association with term labour-onset and delivery. LPS increased IL-1 alpha release significantly only from human placental explants from both term not-in-labour and term after-labour tissues. The data demonstrate differential regulation of IL-1 alpha release from human gestational tissues in association with labour and LPS treatment and the observations support the hypothesis that the labour-associated increase in IL-1 alpha release from the fetal membranes is independent of exposure to bacterial endotoxin.

Amnion↗
PubMed1996

Expression of prostaglandin G/H synthase-1 and -2 in ovine amnion and placenta following glucocorticoid-induced labour onset.

Parturition in the sheep is preceded by an increase in the synthesis of prostaglandins by intrauterine tissues. Prostaglandin G/H synthase (PGHS) is the central enzyme involved in prostanoid production. Its expression is enhanced during late gestation in the ewe. Recent studies have identified two PGHS isozymes, termed PGHS-1 and PGHS-2. The labour-associated expression of the two isozymes of PGHS in the sheep has not been characterized. This study investigated the changes in expression of immunoreactive PGHS-1 and PGHS-2 in ovine amnion and placenta following glucocorticoid-induced labour. Ewes underwent surgery to implant fetal and maternal vascular cannulae and uterine electromyogram electrodes between 118 and 125 days of gestation. Fetal sheep were administered either the glucocorticoid betamethasone (n = 5) or saline (control n = 6) by direct transabdominal intrafetal injection. Ewes from the betamethasone-injected group were killed in the first stage of labour as indicated by uterine electromyographic activity. Ewes from the saline-injected group were killed at the same time to obtain age-matched control tissue. The time taken to euthanasia following induced-labour onset in the glucocorticoid-injected animals was 56.6 +/- 0.8 h post-injection. Plasma endocrine profiles in the maternal and fetal circulation following glucocorticoid injection were comparable to those observed following normal spontaneous delivery. At post-mortem, amnion and cotyledons were collected in liquid N2 and stored at -70 degrees C. Solubilized tissue extracts were prepared and analysed by Western blots using polyclonal antibodies to PGHS-1 and PGHS-2 isozymes. Fetal amnion contained PGHS-1 isozyme at day 133 of gestation, as demonstrated in the saline-injected animals. Slightly higher PGHS-1 immunoreactivity was observed following induced-labour onset, although this did not reach statistical significance (P > 0.05). PGHS-2 enzyme was not detectable in amnion. PGHS-2 expression was also not induced following labour onset. In contrast, PGHS-2 demonstrated enhanced expression following glucocorticoid-induced labour in ovine cotyledon. This tissue contained PGHS-1 enzyme, but immunoreactive levels were minimal and demonstrated limited regulation at labour. These data suggest that the previously reported rise in placental PG production at term in the sheep is predominantly due to increased expression of the PGHS-2 isozyme. This suggests that PGHS-2 contributes to PG production at term labour in sheep or is induced by the mechanisms controlling ovine parturition. PGHS-1 isozyme is produced constitutively in ovine amnion and may contribute to the gestational increase in PG formation by intrauterine tissues.

Amnion↗
PubMed1995

Plasma type II phospholipase A2 levels are elevated in severe preeclampsia.

OBJECTIVE: Our purpose was to compare plasma concentrations of type II phospholipase A2 in normal and preeclamptic pregnancies and to determine whether plasma from preeclamptic patients increases endothelial cell secretion of type II phospholipase A2. STUDY DESIGN: We compared the plasma levels of type II phospholipase A2 in 23 patients with normal pregnancies and 25 patients with strictly defined preeclampsia. Plasma samples were collected throughout pregnancy and stored at -80 degrees C. Patients with preeclampsia were matched closely as possible with controls for maternal age, race, gestational age at blood sampling, and parity. Plasma levels of type II phospholipase A2 were measured by enzyme immunoassay. To investigate endothelial cell type II phospholipase A2 production, we measured levels of prostacyclin and type II phospholipase A2 in conditioned media from cultured human umbilical vein endothelial cells exposed to plasma from preeclamptic and normal pregnant patients. RESULTS: The mean plasma type II phospholipase A2 level in the mild preeclampsia group (6.1 +/- 3.0 ng/ml, n = 6) was not different from that in control patients (6.0 +/- 3.2 ng/ml, n = 23). However, the mean type II phospholipase A2 level in patients with severe preeclampsia (19.9 +/- 12.3 ng/ml, n = 19) was significantly higher when compared with the other two groups (p < 0.001). Prostacyclin concentrations in conditioned media of endothelial cells exposed to plasma from patients with preeclampsia were elevated compared with cells incubated with control plasma (8.6 +/- 1.7 vs 4.0 +/- 5.0 ng/ml, p < 0.05). However, the concentration of type II phospholipase A2 in conditioned medium was not significantly different (1.6 +/- 0.3 vs. 1.8 +/- 1.0 ng/ml, p = 0.40). CONCLUSIONS: Plasma concentrations of type II phospholipase A2 are elevated in preeclampsia and correlate well with the severity of disease. Plasma from preeclamptic women increased secretion of prostacyclin, but not type II phospholipase A2 by endothelial cells in culture.

Case-Control Studies↗
PubMed1995

Secretory type II phospholipase A2 and the generation of intrauterine signals.

Recent advances in the understanding of the metabolism of cell membrane glycerophospholipids and the subsequent generation of biologically active metabolites have provided new insight into their role in normal spontaneous-onset labour and delivery at term, and in preterm labour. In particular, multiple isozymes of the lipolytic enzyme phospholipase A2 (PLA2) have been identified in human gestational tissue during late pregnancy and at the time of labour. Specific isozymes have been identified that are active intracellularly (e.g. cytosolic PLA2) or extracellularly (e.g. Type II and Type IV secretory PLA2). The relative contribution of these isozymes to total PLA2 activity is tissue specific and affected by labour status. The development of isozyme-specific inhibitors of PLA2 may afford the opportunity to better regulate the formation of biologically active phospholipid metabolites within intrauterine compartments. With the identification of secretory PLA2 isozymes in human gestational tissues, a new pathway for materno-fetal and/or intrauterine communication has been established--a pathway in which secretory PLA2 isozymes released by intrauterine tissues act in an autocrine, paracrine or even endocrine fashion to affect glycerophospholipid metabolism, cell membrane fluidity and the generation of biological mediators.

Extraembryonic Membranes↗
PubMed1995

Parathyroid hormone-related protein (PTHrP) concentrations in human amniotic fluid during gestation and at the time of labour.

To establish the changes associated with gestational age and labour status in parathyroid hormone-related protein (PTHrP) concentrations in the amniotic fluid, human amniotic fluid was collected from non-labouring and labouring women at < 37 weeks of gestation (preterm) and at term (> or = 37 weeks). PTHrP was assayed by a specific N-terminal radioimmunoassay. PTHrP concentrations in amniotic fluid obtained from non-labouring women were significantly lower at preterm (15-36 weeks; 14.1 +/- 2.5 pmol L(-1); n = 11) than at term (37-42 weeks; 39.3 +/- 7.6 pmol L(-1); n = 16; P < 0.0009). Concentrations of PTHrP in amniotic fluid obtained from labouring women were also significantly lower at preterm (27-36 week; 12.2 +/- 4.7 pmol L(-1); n = 4; P < 0.01) than at term (37-42 weeks; 63. 8 +/- 19.6 pmol L(-1); n = 9). There were no significant changes in concentration associated with labour status, either at preterm or at term. The physiological significance of elevated amniotic fluid concentrations of PTHrP has yet to be established, but the data are consistent with the suggestion that PTHrP plays a role in fetal membrane function during late gestation.

Amniotic Fluid↗
PubMed1995

Prostaglandin G/H synthase-1 messenger RNA relative abundance in human amnion, choriodecidua and placenta before, during and after spontaneous-onset labour at term.

The aim of this study was to determine the relative abundance of prostaglandin G/H synthase-1 (PGHS-1) mRNA in human amnion, choriodecidua and placenta obtained before (n = 5), during (n = 5) and after spontaneous-onset labour and delivery at term (n = 5). PGHS-1 mRNA relative abundance was not affected by labour status (p > 0.1) nor differently expressed between gestational tissues (p > 0.05). These data are consistent with the hypothesis that PGHS-1 is a constitutively expressed isozyme and that an increase in the relative abundance of mRNA encoding this enzyme is not necessary for the labour-associated increase in prostaglandin formation.

Amnion↗
PubMed1995

Gestational- and labour-associated changes in the relative abundance of prostaglandin G/H synthase-1 and -2 mRNA in ovine placenta.

The aim of this study was to establish the gestational- and labour-associated variation in the relative abundance of prostaglandin synthase-1 (PGHS-1) and prostaglandin synthase-2 (PGHS-2) mRNA in ovine placenta (cotyledons). Cotyledons were collected from non-labouring ewes at 40-145 days of gestation (n = 25) and from ewes in active labour (145-147 days, n = 5). The relative abundance of PGHS-1 and PGHS-2 mRNA transcripts was determined by Northern blot analysis and laser densitometry, using a 2.3 kb sheep and a 1.2 kb mouse cDNA probe respectively. Data were expressed as a ratio of PGHS transcript hybridization/18S rRNA hybridization. During pregnancy, the relative abundance of PGHS-2 mRNA increased sevenfold, from 0.19 +/- 0.04 at 40-85 days (n = 5) to 1.39 +/- 0.05 at 140-145 days (n = 4) (P < 0.01). PGHS-1 mRNA relative abundance did not change significantly (P > 0.05) during gestation. Neither PGHS-1 nor PGHS-2 mRNA relative abundance changed significantly in association with labour onset at term (n = 5) when compared with the relative abundance observed at 140-145 days (n = 4) (P > 0.05). The data obtained in this study are consistent with the hypothesis that PGHS-1 is constitutively expressed in ovine placenta during pregnancy and at the time of labour, and that PGHS-2 is induced during the second half of pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Leukemia inhibitory factor: association with intraamniotic infection.

OBJECTIVE: Our purpose was to investigate whether leukemia inhibitory factor is associated with intraamniotic infection. STUDY DESIGN: A comparative clinical study of amniotic fluid leukemia inhibitory factor concentrations was performed. RESULTS: Leukemia inhibitory factor was undetectable (< 1 ng/ml) by radioreceptor assay during normal pregnancy at midtrimester and at term. Among women in labor those with intraamniotic infection had higher leukemia factor concentrations than those without infection before term (p < 0.001) and at term (p < 0.005). The leukemia inhibitory factor concentrations correlated with the amniotic fluid white blood cell counts (r = 0.47) (p < 0.001). In cultured human gestational tissue explants, leukemia inhibitory factor release was significantly enhanced by endotoxin, interleukin-1 alpha, and tumor necrosis factor-alpha however, leukemia inhibitory factor did not enhance the release of prostaglandin E2 by these tissues. CONCLUSIONS: Amniotic fluid leukemia inhibitory factor concentrations were elevated during intraamniotic infection and gestational tissues released leukemia inhibitory factor in response to bacterial products and inflammatory mediators.

Amnion↗
PubMed1994

Effects of lipopolysaccharide on human placental prostaglandin F2 alpha production in vitro.

The effect of bacterial endotoxin (lipopolysaccharide, LPS), on the release of prostaglandin F2 alpha (PGF2 alpha) from human placental explants was investigated. Both LPS and calcium ionophore A23187 stimulated PGF2 alpha release (p < 0.05). Placental explants, either exposed to LPS and A23187 simultaneously or primed by LPS before A23187 stimulation, resulted in similar increased PGF2 alpha releases, which were higher than the level of LPS alone. The data suggest LPS could increase basal PGF2 alpha release from human placenta, combined with A23187 it may act on PG synthase as well in favour of PGF2 alpha formation.

Calcimycin↗
PubMed1994

Older readers' processing of medical information that contradicts their beliefs.

Older adults' memory for accurate information which either contradicted their previously held false beliefs or affirmed their previously held true beliefs about osteoarthritis was studied. Independent variables included information type (text affirms or disconfirms the reader's initial belief), explicitness of statement (explicit vs implicit statement of the target belief), filler tasks (repetition vs filter tasks), passage order, and time. Participants were 125 adults (65-80 years old) with average vocabularies who self-reported having osteoarthritis for at least two years. In support of a schema-copy plus tag model, we found (a) false alarm rates were higher for schema-related than for topic-related recognition distractors; (b) updating of erroneous opinions from pretest to immediate posttest was positively correlated with maintenance of accurate recognition from immediate to delayed posttest; and (c) disconfirming information was less accurately recognized and recalled than affirming information. Explicit text presentation and repetition of recognition and opinion tasks enhanced accurate recognition of disconfirming information. Findings suggest that older readers often have difficulty distinguishing between their erroneous prior knowledge and accurate information presented in text.

Aged↗
PubMed1994

Bacterial endotoxin increases type II phospholipase A2 immunoreactive content and phospholipase A2 enzymatic activity in human choriodecidua.

The aim of this study was to establish the effect of bacterial endotoxin lipopolysaccharide (LPS) on type II phospholipase A2 (PLA2) content and in vitro net PLA2 enzymatic activity in human choriodecidua. More particularly, the objective was to ascertain whether an increase in type II PLA2 tissue content and PLA2 enzymatic activity is associated with the previously documented stimulatory effect of LPS on prostaglandin E2 (PGE2) release from choriodecidua. Choriodecidua explants were incubated in RPMI 1640 (control) or RPMI 1640 containing LPS (0.1 ng/ml to 10 micrograms/ml) for up to 24 h. Under the incubation conditions utilized, LPS (1 microgram/ml) stimulated the release of PGE2 3-fold (p < 0.001, n = 4 tissues), in a time-dependent manner (p < 0.005). Tissue immunoreactive (ir)-type II PLA2 content and PLA2 enzymatic activity were determined by monoclonal antibody sandwich ELISA and radiolabeled enzyme assay procedures, respectively. The tissue content of type II PLA2 immunoreactivity in choriodecidua obtained from women (n = 7) at term but not in labor averaged 155 +/- 24 ng/ml DNA. PLA2 enzymatic activity average 29.8 +/- 5.1 pmol phosphatidylethanolamine (PE)/mg DNA/h. LPS at a concentration of 1 microgram/ml increased immunoreactive type II PLA2 tissue content by 180% of the control value (p < 0.05, n = 7) within 1 h of exposure and remained significantly elevated for 18 h when compared to controls (174% of control, p < 0.01, n = 7).(ABSTRACT TRUNCATED AT 250 WORDS)

Chorion↗
PubMed1994

Tumour necrosis factor alpha during human pregnancy and labour: maternal plasma and amniotic fluid concentrations and release from intrauterine tissues.

The aims of this study were: to quantify immunoreactive tumour necrosis factor alpha (TNF-alpha) concentrations in maternal plasma and amniotic fluid obtained from women during pregnancy and labour, both at term and preterm; and to establish the effects of bacterial endotoxin and cytokines on the in vitro release of TNF-alpha from intrauterine tissues. Maternal plasma TNF-alpha concentrations did not change during pregnancy (457.2 +/- 102.9 ng/l, mean +/- SEM, N = 52) or at the time of labour (543.5 +/- 138.6 ng/l, N = 43). In contrast, amniotic fluid TNF-alpha concentrations increased significantly (p < 0.05) during pregnancy (early pregnancy, EP, 93.0 +/- 24.8 ng/l, N = 7; preterm not-in-labour, PNIL, 186.8 +/- 42.9 ng/l, N = 16; term not-in-labour. TNIL, 499.7 +/- 150.9 ng/l, N = 13) and in association with preterm labour (preterm in-labour, PIL, 958.7 +/- 575.6 ng/l, N = 5 vs PNIL, 186.8 +/- 42.9 ng/l, N = 16). Choriodecidual and placental explants (N = 3) maintained in in vitro culture released TNF-alpha. Furthermore, the release of TNF-alpha was increased significantly (p < 0.05) by bacterial endotoxin (lipopolysaccharide, 10 ng/l-10 mg/l) but was not affected by the following cytokines at the indicated doses: interleukin-1 alpha (0.28 nmol/l), interleukin-6 (12.5 nmol/l), granulocyte colony-stimulating factor (2.5 nmol/l), granulocyte-macrophage colony-stimulating factor (35 nmol/l), macrophage colony-stimulating factor (1.2 nmol/l), leukaemia inhibitory factor (0.45 nmol/l) and transforming growth factor-beta (0.4 nmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Amnion↗
PubMed1993

Type II phospholipase A2 in human gestational tissues: extractable immuno- and enzymatic activity in fetal membranes.

In this study, we have established the presence of immunoreactive (ir) Type II PLA2 in human amnion and choriodecidua obtained from women at term prior to the onset of labour. The content of irType II PLA2 present in 1 M NaCl extracts of choriodecidua and amnion averaged 3.5 +/- 3.1 and 10.6 +/- 5.2 ng/mg tissue protein (n = 3), respectively. PLA2 enzymatic activity present in the same tissues averaged 1.3 +/- 0.2 and 1.9 +/- 0.7 nmol phosphatidylethanolamine (PE) hydrolysed/mg tissue protein per h (n = 3), respectively. To allow intra-patient comparison of the relative distribution in gestational tissues, irType II PLA2 and PLA2 enzymatic activity was also determined in placenta obtained from the same group of women, and averaged 26.0 +/- 7.0 ng/mg tissue protein and 3.5 +/- 1.0 nmol PE hydrolysed/mg protein per h (n = 3), respectively. As has been previously reported for human placenta, the recovery of Type II PLA2 and PLA2 enzymatic activity from amnion and choriodecidua was increased between 16- and 25-fold when tissues were homogenized in high-ionic strength media (i.e., 10% (w/v) ammonium sulphate or 1 M NaCl) compared with that recovered when tissues were homogenized in low-ionic strength media (i.e., 0.32 M sucrose-20 mM Hepes). The data obtained represent the first quantitative estimates of immunoreactive Type II PLA2 in human amnion and choriodecidua, and support the conclusion that previous analyses of the PLA2 enzymatic activity present in gestational tissues have essentially excluded the contribution made by this PLA2 isozyme to net enzymatic activity. We suggest that this isozyme represents a major component of the PLA2 enzymatic activity present in human gestational tissues at term and that it contributes significantly to the phospholipid metabolism and arachidonic acid release which occurs during late pregnancy and at the time of labour.

Extraembryonic Membranes↗
PubMed1993

Type II phospholipase A2 in human gestational tissues: subcellular distribution of placental immuno- and catalytic activity.

The aims of this study were to determine the subcellular distribution of Type II phospholipase A2 immunoactivity (irPLA2) and in vitro net PLA2 catalytic activity in human term placenta and to establish the efficacy of previously utilised homogenisation procedures with respect to the quantitative recovery of Type II PLA2 immunoreactive and in vitro net PLA2 catalytic activity. Type II PLA2 immunoactivity and PLA2 catalytic activity recovered in 900 x g supernates prepared from placental tissue (n = 3) homogenised in low ionic strength media (sucrose 0.32 M Hepes 20 mM; phosphate-buffered saline or phosphate-buffered saline containing 3 mM EGTA) was less than 10% of that recovered following homogenisation in high ionic strength medium (ammonium sulphate 10%, w/v). The subcellular distribution of Type II PLA2 immunoactivity and PLA2 catalytic activity was established by the differential centrifugation (10,000, 20,000 and 100,000 x g) of placental homogenates (n = 3). Although Type II PLA2 immunoactivity was equally distributed throughout the particulate subcellular fractions examined, PLA2 catalytic activity increased by comparison in 100,000 x g particulate material. This apparent dissociation between irType II PLA2 and catalytic activity may indicate the presence of other types of PLA2 in this fraction. The data obtained in this study indicate that previous studies which have utilised low ionic strength extractions of human gestational tissue to characterise PLA2 catalytic activity and subcellular distribution have largely excluded the contribution made by Type II PLA2. Consequently, much of the available published data on the role of PLA2 in human parturition is inadequate. A reappraisal of this enzyme's contribution to the biochemical events associated with human pregnancy and labour is required.

Female↗
PubMed1993

Endocrine correlates of placental permeability during gestation in the pig.

1. Hormone and electrolyte concentrations were determined in amniotic and allantoic fluid collected from sows at 47-112 days of gestation and correlated with placental and fetal membrane electrolyte permeability. 2. Significant differences between the electrolyte and endocrine gestational profiles of amniotic and allantoic fluid were identified. 3. The principal endocrine correlate (r > 0.62; P < 0.01) of gestational changes in the sodium and chloride permeabilities of the porcine placenta and fetal membranes was found to be the concentration of oestrogen in the amniotic fluid.

Allantois↗