SAR150640, a selective beta3-adrenoceptor agonist, prevents human myometrial remodelling and activation of matrix metalloproteinase in an in vitro model of chorioamnionitis

BACKGROUND AND PURPOSE

The uterine pathophysiology underlying inflammatory conditions such as chorioamnionitis remains largely unclear. As we have shown that beta(3)-adrenoceptors act as regulators of myometrial inflammation, we wanted to investigate the potential role of beta(3)-adrenoceptors in preventing uterine remodelling induced by inflammation.

EXPERIMENTAL APPROACH

The consequences of human chorioamnionitis on myometrial remodelling were characterized by Sirius Red staining and metalloproteinase (MMP) expression, and compared with the effects of incubating human myometrial samples with Escherichia coli lipopolysaccharide (LPS) in vitro. We also assessed the effect of SAR150640, a selective beta(3)-adrenoceptor agonist, on the production and activity of MMPs.

KEY RESULTS

Chorioamnionitis was associated with a 46% decrease in total collagen, as well as over-expression of MMP2 (+61%) and MMP9 (+84%); both effects were reproduced by incubation with LPS (10 microg x mL(-1), 48 h). LPS-induced over-expression of MMP2 and MMP9 in normal human myometrium was paralleled by an overactivity of the proteins. Both over-expression and overactivity were prevented by the beta(3)-adrenoceptor agonist SAR150640 in a concentration-dependent manner. SAR150640, by itself, did not exhibit any effect on MMP production in control tissues.

CONCLUSIONS AND IMPLICATIONS

This study shows that inflammation was associated with an intense remodelling of human myometrium, a process likely to be explained by MMP activation. Our study emphasizes the potential therapeutic relevance of beta(3)-adrenoceptor agonists to the treatment of preterm labour and other uterine inflammatory conditions.

Occupational predictors of pregnancy outcomes in Irish working women in the Lifeways cohort

OBJECTIVE

The objective of this study was to explore the association between occupational factors and pregnancy outcomes in a prospective cohort of Irish pregnant women.

DESIGN

This study has a prospective design.

POPULATION

The Lifeways cohort included 1124 pregnant women, 676 of whom delivered a single baby and were working at their first prenatal care visit when they filled in a self-administered questionnaire.

METHODS

Occupational factors were measured using this questionnaire and included eight factors describing job and working conditions. Data including pregnancy outcomes were also obtained from clinical hospital records. Logistic regression analysis was used to adjust for well-known risk factors.

MAIN OUTCOME MEASURES

Birthweight (< or =3000 g and < or =2500 g), preterm delivery (<37 gestation weeks) and small-for-gestational-age.

RESULTS

Significant associations were found between physical work demands and low birthweight (< or =2500 g) and working with between a temporary contract and preterm delivery. Trends were also observed between working 40 hours or more a week and shift work, and birthweight of 3000 g or less. The study of a cumulative index showed that being exposed to at least two of these occupational factors significantly predicted birthweight of < or =3000 g (OR = 2.44, 95% CI: 1.17-5.08) and of < or =2500 g (OR = 4.65, 95% CI: 1.08-20.07) and preterm delivery (OR = 5.18, 95% CI: 1.00-27.01).

CONCLUSIONS

Our findings suggest that occupational factors may predict birthweight through their predictive effects on preterm delivery. This is one of the few prospective studies on pregnancy outcomes that include working conditions. As they may be modifiable, occupational factors deserve more attention in relation to birth outcomes.

Dietary habits of pregnant women in Ireland

This analysis of the Lifeways Cohort study mothers during pregnancy (n = 1124), utilises information from a standard food frequency questionnaire completed at baseline recruitment during early pregnancy. We demonstrate that 76% of women achieved recommended intakes of 5 plus portions of fruit and vegetables daily, though this is strongly socially patterned, inversely associated with age and positively associated with level of education. Achievement of the other recommended shelf intakes of the Food Pyramid is much lower, ranging from 12% achieving the recommended sparing intake of foods high in fat, salt or sugar, to 45% consuming the recommended 3 portions per day of meat and poultry. General medical services eligible respondents are generally less likely to achieve recommended intakes. While 61% of women under 25 years old stopped drinking during pregnancy, this dropped to 38% of expectant mothers over 35 years. Less than half (45%) of those (n = 860) who responded specifically to the question reported peri-conceptual folate supplement intake, again strongly socially patterned. These findings both provide important prevalence data and highlight the need for more concerted and supportive health promotion interventions during pregnancy.

Self-reported pre-pregnancy maternal body mass index and infant birth-weight

This analysis examines the association between maternal characteristics, particularly body mass index (BMI) and infant birth weight in 1048 live infants. Mean reported pre pregnancy BMI of mothers was 23.74 kg/m2 (SD 4.21). The educational level of the mother's parents was independently associated with maternal BMI, those with higher educated parents having a lower reported BMI (F = 2.787, p = 0.029). Mean infant birth weight was 3493 g (SD 18.1) and there was a strong graduated relationship to estimated gestational age. In a sub-group of participating maternal grandmothers (n = 171), reported BMI was 26.7Kg/m2. The BMI of expectant mothers was significantly associated with their own mother's BMI. (r = 0.179, p = 0.005) in this sub-group. These preliminary findings, which will be investigated further with recorded height and weight information, suggest that familial factors are influential, perhaps through genetic predisposition or shared socio-cultural factors such as diet.

Socio-demographic, lifestyle and cross-generation predictors of self-rated health in mothers during pregnancy

The Lifeways Cross-generation study was established to assess the influence of socio-economic and familial characteristics on the health status and early development of children. Between October 2001 and June 2002, 1124 women were recruited to the Lifeways study at booking or first visit to maternity hospital. Lifeways mothers were 29.4 (SD 5.9) years old at recruitment, two-thirds from greater Dublin area, 17.9% held a General Medical Services (GMS) card, 64.3% were married and 40.8% were third level educated. At uni-variate level, GMS eligibility, own and parents' education and marital status all predicted mother's self rated health during pregnancy, whilst in the final multivariate logistic regression model, GMS status, household-adjusted income, marital status and grand-maternal education were each independently predictors. The Lifeways cohort confirms the importance of social position in predicting health in pregnant Irish women.

Medium-Fidelity Medical Simulators: Use in a Pre-Hospital,Operational, Military Environment

On Operation Telic 6, the UK Med Group consisting of 3 Close Support Medical Regiment and 205 Field Hospital (Volunteers) deployed to provide medical support to coalition forces in Iraq. Personnel were drawn from Regular and Territorial Units, plus additional medical support from Armies of the Czech Republic and Denmark. The efficient delivery of operational emergency medical care hinged upon the successful integration of personnel from these units. We report on the use of a medium-fidelity simulator, in a pre-hospital and hospital environment over a three month period on an operational tour. In conducting 42 exercises (12 of which commenced in a pre-hospital environment), we have demonstrated the feasibility of the system in rehearsing the management of the major trauma patient. This training was used to enhance teamwork, identify system deficiencies and practise solutions in a safe environment. This paper discusses our experiences in relation to the current literature on this expanding area of trauma training.

Fetal cortisol in relation to labour, intrapartum events and mode of delivery

We set out to measure fetal cortisol in the human umbilical vein in relation to onset of labour, intrapartum complications and mode of delivery. Umbilical cord venous samples were obtained after delivery from 98 infants and serum total cortisol was measured. The onset of spontaneous labour, induction of labour, elective caesarean section, spontaneous vaginal delivery, emergency caesarean section in labour, instrumental delivery, the presence of meconium staining of the liquor and umbilical artery pH were examined in relation to serum fetal cortisol. Spontaneous onset of labour, mode of delivery, meconium staining of the liquor and gestational age were independent predictors of umbilical venous cortisol levels. Those infants delivered by elective caesarean section had the lowest cortisol levels, while the highest levels were recorded in those infants following instrumental delivery. Fetal cortisol is significantly elevated in association with spontaneous human parturition and is highest Its among babies born by instrumental delivery.

Effects of thyrotropin-releasing hormone on human myometrium and umbilical vasculature in vitro

OBJECTIVE

The purpose of this study was to investigate the direct effects of thyrotropin-releasing hormone on isolated human myometrium that was obtained during pregnancy and on human umbilical vasculature in vitro.

STUDY DESIGN

Isolated human myometrial strips were dissected from biopsy specimens that were obtained at elective cesarean delivery and suspended for isometric recording under physiologic conditions. The effects of cumulative additions of thyrotropin-releasing hormone (10(-9)-10(-4) mol/L) on oxytocin-induced myometrial contractility were evaluated. The effects of thyrotropin-releasing hormone (10(-9)-10(-4) mol/L) on umbilical vessel (artery and vein) resistance in vitro were investigated with the use of isolated ring preparations.

RESULTS

Thyrotropin-releasing hormone exerted a significant concentration-dependent relaxant effect on pregnant human myometrial tissue, which ranged from 3.54% (10(-9) mol/L, P=.935) to a net cumulative total of 21.06% (10(-4) mol/L, P<.001). Thyrotropin-releasing hormone also exerted a concentration-dependent relaxant effect on human umbilical vasculature that ranged from 12.51% (10(-9) mol/L, P=.994) to a net cumulative total of 23.27%+/-4.87% (SEM, 10(-4) mol/L, P<.01) in umbilical artery. For umbilical vein, the relaxant effect ranged from 1.80% (10(-9) mol/L, P=.998) to a net cumulative total of 14.64% (10(-4) mol/L, P<.009).

CONCLUSION

Thyrotropin-releasing hormone exerts a significant relaxant effect in human myometrium and in human umbilical vasculature and highlights a potential physiologic role for this neuropeptide in these tissues. These findings have clinical implications for the therapeutic use of thyrotropin-releasing hormone antenatally.

Attitudes towards routine prenatal diagnostic investigations in obstetric practice in the Republic of Ireland

The aim of this study was to evaluate the attitudes of pregnant women towards prenatal diagnosis in the Republic of Ireland. A questionnaire was administered to all women attending the antenatal clinic at University College Hospital, Galway between January and May 1999. 1042 women participated in the study and 1012 (97%) questionnaires were completed correctly. The majority of women, 763 (75.4%) and 748 (73.9%) respectively, would avail of a fetal anomaly scan or biochemical screening if available. However, confusion exists about the purpose of ultrasound scans currently available. The majority of respondents (71%) thought that the purpose of the currently available scan was to detect fetal abnormality. In reality, the primary purpose of the scan currently available is for other purposes and the detection of fetal abnormality is performed opportunistically rather than systematically. This confusion may reflect poor provision of information to our antenatal patients and should be addressed within by the obstetric service.

Surgically relevant structure on the ascending aorta

We have examined the transverse vascularized ridge observed on the anterior surface of the intra-pericardial aorta during cardiac surgery. The ridge was a consistent feature of 20 consecutive cardiac patients and 11 cadavers no more than 2 days post-mortem. The aortic ridge was absent, however, in four of five embalmed cadavers additionally examined, probably due to the embalming process. Histological examination showed the ridge to be well vascularized, well innervated and composed of adipose tissue. This structure has surgical relevance as a possible source of post-operative hemorrhage, sometimes necessitating re-sternotomy.

Ultrasound detection and perinatal outcome of fetal trisomies 21, 18 and 13 in the absence of a routine fetal anomaly scan or biochemical screening

OBJECTIVES

To determine the prenatal detection rate of abnormality (fetal anomaly or growth restriction) in pregnancies complicated by fetal trisomies 21, 18 and 13 in an obstetric population managed without routine biochemical or sonographic screening tests and to assess the perinatal outcome of these pregnancies.

SUBJECTS AND METHODS

This was a retrospective analysis of obstetric and neonatal data pertaining to infants born with trisomy 21, 18 or 13 (n = 82) diagnosed between 1989 and 1997 (23 762 deliveries).

RESULTS

Antenatal suspicion of aneuploidy, based on the detection of growth restriction or fetal anomaly, was present in 18.3% (11 of 60) of fetuses with trisomy 21, in 81.2% (13 of 16) of fetuses with trisomy 18, and in 83.3% (five of six) of fetuses with trisomy 13. The antenatal detection rates for growth restriction were accurate whereas the antenatal detection rates for fetal anomalies were poor. Intrauterine fetal death occurred in 18.8% of fetuses with trisomy 18 (three of 16) and in 50% (three of six) of cases of trisomy 13. For babies born alive with trisomy 18 or 13 the neonatal mortality was 93.8% (15 of 16). All cases of trisomy 21 fetuses survived beyond the perinatal period and the antepartum and intrapartum details of these pregnancies were unremarkable.

CONCLUSION

In obstetric practice without routine biochemical or sonographic screening tests the detection of findings suggestive of aneuploidy is low for trisomy 21, but is high for trisomies 18 and 13. These findings provide information for counseling about the antenatal, intrapartum, and neonatal course of these trisomies.

Expression of mRNA transcripts for ATP-sensitive potassium channels in human myometrium

The molecular mechanisms regulating human uterine quiescence and parturition are poorly understood. Potassium channels are central to regulation of cell membrane potential and contractility of smooth muscle. The aim of this study was to examine the expression of ATP-sensitive potassium channel (K(ATP) channel) subunits in human myometrium, and to investigate for possible differential expression of these subunits in myometrium obtained from three different functional states: (i) non-pregnant (NP); (ii) late pregnant not in labour (PNL); and (iii) late pregnant in labour (PL). RT-PCR detected the presence of mRNA for four subunits of K(ATP) channels (Kir6.1, Kir6.2, SUR1 and SUR2B) in the three tissue types. Quantitative analysis of these subunits was achieved with real-time RT-PCR using Lightcycler(TM) technology. This analysis showed that there were significantly higher levels of Kir6.1 and SUR2B transcripts in NP myometrium compared with those measured in myometrium obtained during pregnancy (P < 0.001). Lower levels of Kir6.2 and SUR1 mRNA expression were found, although higher transcript levels in NP myometrium (P < 0.05) were still observed. Our results indicate that the major K(ATP) channel expressed in human myometrium is composed of Kir6.1 and SUR2B, and that down-regulation of this channel may facilitate myometrial function during late pregnancy.

Corticosteroids and fetal vasculature: effects of hydrocortisone, dexamethasone and betamethasone on human umbilical artery

OBJECTIVE

To investigate the direct effects of corticosteroids on human umbilical artery resistance, in vitro.

DESIGN

Prospective laboratory study.

SETTING

University teaching hospital.

SAMPLES AND METHODS

Umbilical artery samples were obtained following normal, term deliveries (n = 50) and dissected rings were suspended for isometric recording under physiological conditions. The effects of hydrocortisone (10(-9) - 10(-4) M), dexamethasone (10(-9) - 10(-4) M) and betamethasone (10(-9) - 10(-4) M) on umbilical artery resistance were measured in vitro.

MAIN OUTCOME MEASURES

Changes in umbilical artery resistance, in vitro.

RESULTS

Hydrocortisone (n = 12) exerted a vasodilatory effect on human umbilical artery at all concentrations studied compared with vehicle control experiments (n = 12) (P < 0.0001). The mean net relaxant effect of hydrocortisone ranged from 11.77% (10(-9) M) to 57.01% (10(-4)). Both exogenous compounds, dexamethasone (n = 12) and betamethasone (n = 12), similarly exerted a significant relaxant effect on human umbilical artery tone (P < 0.05-0.01), compared with vehicle control experiments (n = 12). The mean net relaxant effect of dexamethasone ranged from 14.43% (10(-9) M) to 38.12% (10(-4)) and that of betamethasone ranged from 6.02% (10(-9) M) to 42.30% (10(-4)), in a cumulatively increasing fashion. There was a non-significant trend towards a greater vasodilatory effect of dexamethasone than betamethasone at lower bath concentrations studied.

CONCLUSION

Corticosteroids exert a direct and potent vasodilatory effect on human umbilical artery resistance in vitro, thus providing an explanation for the previously unexplained vascular effects associated with antenatal administration of corticosteroids.

Amino-terminal pro-brain natriuretic peptide in normal and hypertensive pregnancy

OBJECTIVES

To investigate serum levels of amino-terminal pro-brain natriuretic peptide (Nt pro-BNP) as an index of left-ventricular function in normal pregnancy and pregnancies complicated by hypertension and also to investigate levels in both primigravid and multigravid women.

METHODS

Women with hypertension in pregnancy (at least two readings of systolic blood pressure > 140 mm Hg and diastolic blood pressure > 90 mm Hg) (n = 24) and normotensive women (n = 42) were included in the study. Serum Nt pro-BNP was measured using an enzyme-linked immunosorbent assay technique.

RESULTS

The median serum Nt pro-BNP level in pregnancies complicated by hypertension was 420 fmol/L, which was significantly greater than that measured in samples obtained from normotensive women in pregnancy (340 fmol/L) (p = 0.03). There was a nonsignificant trend toward increased levels in proteinuric as compared to nonproteinuric hypertension in pregnancy. Multigravida had higher Nt pro-BNP levels (n = 26; median Nt pro-BNP = 358 fmol/L) than primigravida (n = 16; median Nt pro-BNP = 278 fmol/L) (p = 0.01) in association with normal pregnancy. Multigravida also demonstrated a dramatic rise in serum Nt pro-BNP levels in association with hypertension in pregnancy (n = 13; median Nt pro-BNP = 572 fmol/L) as compared to normal pregnancy (n = 26; median Nt pro-BNP = 358 fmol/L) (p = 0.009).

CONCLUSION

Serum Nt pro-BNP is elevated in women with hypertensive disorders of pregnancy, indicating elevated left-ventricular filling pressures. Measured serum levels in both normal and hypertensive pregnancy are higher in multigravida than in primigravida.

Expression and modulation of Rho kinase in human pregnant myometrium

There is little information outlining the role of Rho kinase, RhoA, and calcium sensitization in regulation of human uterine contractility during pregnancy. The aims of this study were to investigate the expression of RhoA, and the Rho kinases ROCK I and ROCK II in human pregnant myometrium, to evaluate the effects of Rho kinase inhibition on pregnant human myometrial contractility in vitro, and to compare these effects with those of the calcium channel blocker nifedipine. RT-PCR using primers for RhoA, ROCK I and ROCK II was performed on mRNA isolated from human pregnant myometrium. Isometric recording was performed in isolated myometrial strips obtained at Caesarean section. The effects of the Rho kinase inhibitor Y-27632 (1 nmol/l to 10 mmol/l), and nifedipine (1 nmol/l to 10 mmol/l), on oxytocin (0.5 nmol/l) induced contractions were measured and compared. Expression of RhoA, ROCK I and ROCK II mRNA was identified in human pregnant myometrium (n = 3). Y-27632 exerted a potent relaxant effect on myometrial contractility with a pD(2) value (+/- SEM) of 7.63 +/- 0.38 (n = 6). The maximum net relaxant effect (+/- SEM) was 72.3 +/- 6.1% (n = 6). Corresponding values for nifedipine were 7.24 +/- 0.48 (n = 6; P = 0.469) and 93.40 +/- 3.1% (n = 6; P = 0.028). Rho A/Rho kinase-mediated calcium sensitization may play role in the physiology of human parturition, and pharmacological inhibition of this pathway may therefore provide a novel approach to tocolysis for pre-term labour.

Uterine relaxant effects of cyclooxygenase-2 inhibitors in vitro

OBJECTIVE

To compare the effects of three cyclooxygenase-2 (COX-2) inhibitors: nimesulide, meloxicam, and celecoxib, which exhibit varying COX-2 selectivity, on contractile activity in pregnant (before and after labor) and nonpregnant human myometrial tissue in vitro.

METHODS

Isometric tension recording was performed under physiologic conditions in isolated myometrial strips obtained from 33 women undergoing hysterectomy or either elective or emergency cesarean section. The effects of cumulative additions of nimesulide, meloxicam, and celecoxib (between 1 nmol/L and 100 micromol/L) on myometrial contractility were measured, and values for -log(10) EC(50) and mean maximal inhibition were compared.

RESULTS

Nimesulide, meloxicam, and celecoxib exerted significant relaxant effects on contractility in nonpregnant, pregnant nonlabor, and pregnant labor myometrial strips. Values for -log(10) EC(50) values (+/- standard error of the mean) were as follows: nimesulide (nonpregnant) 5.14 +/- 0.93 (n = 6), (pregnant nonlabor) 4.91 +/- 0.75 (n = 6), and (pregnant labor) 5.84 +/- 0.35 (n = 6); meloxicam (nonpregnant) 6.53 +/- 0.57 (n = 6), (pregnant nonlabor) 4.80 +/- 0.71 (n = 6), and (pregnant labor) 5.62 +/- 0.21 (n = 6); celecoxib (nonpregnant) 6.15 +/- 0.99 (n = 6), (pregnant nonlabor) 7.08 +/- 0.98 (n = 6), and (pregnant labor) 7.25 +/- 0.99 (n = 3). Celecoxib exhibited greater potency than nimesulide or meloxicam (P < .01). The range of maximal relaxation values achieved in the three tissue types were as follows: nimesulide 68-70% (n = 18; P < .01), meloxicam 69-84% (n = 18; P < .01), and celecoxib 69-77% (n = 15; P < .01).

CONCLUSION

COX-2 inhibitors exert significant relaxation in human myometrium with a similar potency in nonpregnant and pregnant (before and after labor onset) tissues. Celecoxib, a COX-2 specific inhibitor, was more potent than nimesulide or meloxicam, COX-2 preferential inhibitors.

Cardiac troponin I and N-terminal pro-brain natriuretic peptide in umbilical artery blood in relation to fetal heart rate abnormalities during labor

The use of continuous fetal heart rate (FHR) recordings to monitor fetal well-being during labor is standard clinical practice in developed countries. Little is known about the relationship, if any, that exists between these FHR abnormalities and the fetal cardiac musculature and function. The aim of this study was to investigate umbilical artery serum levels of cardiac troponin I, a sensitive and specific marker of myocardial necrosis, and N-terminal pro-brain natriuretic peptide (pro-BNP), a sensitive marker of left ventricular dysfunction, in relation to FHR abnormalities. Umbilical artery blood samples were taken from 27 cases immediately after delivery of the infant. There was evidence of significant FHR abnormalities in 11 of these cases (group 2) and the FHR recording was normal in 16 cases (group 1). The mean N-terminal pro-BNP level in umbilical artery serum in group 2 was 413 fmol/L (SEM = 85) and in group 1 was 223 fmol/L (SEM = 28)(p = 0.022). There was no significant difference observed in cardiac troponin I levels between the two groups. Umbilical artery serum N-terminal pro-BNP is elevated in association with fetal heart rate abnormality in the late stage of labor. This finding suggests that some degree of cardiac compromise accompanies FHR abnormality.

Human chorionic gonadotrophin inhibition of pregnant human myometrial contractility

OBJECTIVE

To evaluate the effect of human chorionic gonadotrophin (hCG) on pregnant human myometrial contractility in vitro and to determine whether the hCG-elicited effect was oestrogen dependant.

METHODS

Isometric tension recording was performed under physiological conditions in isolated myometrial strips from biopsies obtained at elective caesarean section. The effect of cumulative additions of hCG (0.001, 0.01, 0.1, 1.0 and 10 iu/mL) on myometrial contractility was evaluated. Secondarily, the contractile activity of pregnant myometrium following hCG exposure was investigated in tissue pre-treated with beta-oestradiol.

RESULTS

hCG exerted a statistically significant relaxant effect on pregnant human myometrial tissue. The relaxant effect increased with increasing concentrations of hCG from 8.96% (SEM 2.06) (0.001 iu/mL hCG: P < 0.01 ) to a net cumulative total of 58.50% (SEM 3.74) (10 iu/mL hCG; P < 0.01). The relaxant effect was also time-dependant, increasing in magnitude throughout the duration of experiments. Beta-oestradiol did not significantly affect the response of myometrial tissue to hCG.

CONCLUSIONS

These results clearly demonstrate that hCG exerts a significant concentration-dependant relaxant effect on human myometrial tissue obtained rate in pregnancy. These findings outline an inhibitory physiological role of hCG on human myometrial contractility and raise the possibility of its potential use as a tocolytic.

Beta-3 versus beta-2 adrenergic agonists and preterm labour: in vitro uterine relaxation effects

OBJECTIVE

1. To investigate the effects of the selective beta-3 adrenoreceptor agonist, BRL 37344, on human pregnant myometrial contractility in vitro. 2. to compare these effects with those of the beta-2 adrenoreceptor agonist, ritodrine.

METHODS

Isometric tension recording was performed under physiological conditions in isolated myometrial strips from biopsies obtained at elective caesarean section. Following pre-incubation with oxytocin (10(-9) M), the effects of cumulative additions of BRL 37344 or ritodrine (10(-8)-10(-3.5) M) on myometrial contractility were investigated. Results were expressed as -log EC50 (pD2) and mean maximal inhibition achieved for both drug compounds.

RESULTS

BRL 37344 exerted a concentration dependant relaxant effect on myometrial contractions in all strips exposed [pD2, 7.26 (0.48) (SEM); mean maximal inhibition 61.98 (4.89%); n = 6]. Similarly, ritodrine exerted a concentration dependant inhibition of myometrial contractility in all strips exposed [pD2 = 7.40 (0.28); mean maximal inhibition 59.49 (3.97%); n = 6]. There was no significant difference between calculated pD2 values (P = 0.65) or mean maximal inhibition achieved (P = 0.79).

CONCLUSIONS

The beta-3 adrenoreceptor agonist BRL 37344 induced relaxation of human myometrial contractions with similar potency to that of the most commonly used tocolytic agent ritodrine. This raises the possibility that the novel beta-3 adrenoreceptor agonists may have potential as therapeutic agents for human preterm labour. In view of their reported reduced cardiovascular side effects their potential clinical use requires further evaluation.

Effect of parathyroid hormone-related peptide on human and rat myometrial contractility in vitro

OBJECTIVES

The aims of this study were primarily to investigate the effects of parathyroid hormone-related peptide (human fragment 1-34) on human nonpregnant and pregnant (nonlabor and labor) myometrial contractility in vitro and secondarily to compare these effects with those of parathyroid hormone-related peptide on rat myometrial contractility.

STUDY DESIGN

Isometric tension recording was performed under physiologic conditions in isolated myometrial strips obtained at hysterectomy and cesarean delivery and from Sprague-Dawley rats. The effect of cumulative additions of parathyroid hormone-related peptide (1, 10, and 100 nmol/L) on myometrial contractility was measured and the significance of results was assessed by 2-way analysis of variance.

RESULTS

Parathyroid hormone-related peptide exerted a statistically significant net relaxant effect on myometrial contractility in human nonpregnant myometrium (34.71%; P<.01), in human pregnant myometrium obtained before (18.27%; P <.05) but not after (10.32%; P>.05) the onset of labor, and in rat tissue (31.60%; P<.01).

CONCLUSIONS

Parathyroid hormone-related peptide exerts a relaxant effect on human and rat myometrial tissue. In human myometrium, sensitivity to parathyroid hormone-related peptide is reduced in pregnancy and abolished by the onset of labor.

Severe HELLP syndrome remote from term

A 27 year-old nulliparous woman was admitted to University College Hospital Galway with severe preeclampsia at 21 weeks 'gestation. In addition, there was evidence of HELLP syndrome with renal failure. A decision was made to end the pregnancy to save the mother's life. Labour was induced with misoprostol and vaginal delivery of a male stillborn fetus weighing 250 g was achieved after 19 hours. The condition of the patient improved gradually following delivery. Renal impairment, however, persisted postpartum. HELLP syndrome is a life-threatening complication of pregnancy which can only be cured by delivery. Other therapeutic modalities are only palliative but may improve the outcome for the very premature viable fetus. Conservative management is not an option when HELLP syndrome occurs long before fetal viability has been reached.

Cardiac troponin I in pre-eclampsia and gestational hypertension

OBJECTIVE

To investigate serum cardiac troponin I, a sensitive marker of cardiac myocyte damage, in normal pregnancy and pregnancies complicated by hypertension with and without significant proteinuria.

DESIGN

Prospective cross sectional study.

SETTING

University hospital delivery suite.

SAMPLE

Serum samples obtained from women in normal pregnancy and in pregnancies complicated by hypertension with and without significant proteinuria.

METHOD

Women with hypertension in pregnancy (at least two readings of systolic blood pressure > 140 mmHg and diastolic blood pressure > 90 mmHg) (n = 26) and normotensive women (n = 43) were included in the study. Serum cardiac troponin I was measured using Beckman Access immunoassay.

MAIN OUTCOME MEASURE

Serum cardiac troponin I level in the pregnancies complicated by hypertension (with and without significant proteinuria) compared with the levels measured in normotensive women.

RESULTS

The median serum cardiac troponin I level in pregnancies complicated by hypertension was 0.118 ng/mL (n = 26) which was significantly greater than that measured in samples obtained from normotensive women in pregnancy (0.03 ng/mL; n = 43) (P < 0.0001). There were higher median serum cardiac troponin I levels in hypertensive women with significant proteinuria (0.155 ng/mL; n = 6), compared with those without proteinuria (0.089 ng/mL; n = 20; P = 0.03).

CONCLUSION

Serum cardiac troponin I is elevated in women with hypertensive disorders of pregnancy indicating some degree of cardiac myofibrillary damage in these disorders.

Perinatal factors and preterm delivery in an Irish obstetric population

The aim of this study was to ascertain the incidence of preterm delivery, the associated etiological factors and consequent perinatal mortality in an Irish obstetrical population. All deliveries between 24 + 0 and 36 + 6 weeks of gestation that occurred during the five year period 1992-1996 were included in the study. The overall group of preterm deliveries was also analyzed separately as an early preterm group (24 + 0-31 + 6 weeks gestation) and a late preterm group (32 + 0-36 + 6 weeks gestation). The overall incidence of preterm delivery was 5.5% (n = 683) with 1% (n = 122) occurring in the early preterm group and 4.5% (n = 561) in the late preterm group. The etiological factors contributing to preterm delivery in our population together with their frequency of occurrence in both early and late preterm groups are outlined. Spontaneous unexplained preterm delivery, multiple pregnancy, and hypertensive disorders of pregnancy were the commonest etiological factors for preterm delivery. The perinatal mortality rate (PMR) was 57 per 1000 (n = 39) in the preterm group overall with a 213/1000 PMR in the early preterm group and a 23/1000 PMR in the late preterm group.

Development of an optimized feeding technology for dairy cows: improvement in resistance to ruminal proteases in the de novo-designed protein MB-1

We have previously reported on MB-1, a designer protein with potential application in animal nutrition. Having a high content of selected essential amino acids, MB-1 should provide limiting nutrients for animals and promote growth and production. However, the protein was found to have marginal conformational and proteolytic stability, and, thus, strategies for stabilizing MB-1 were elaborated. We discuss the synthesis of MB-1-Cys dimer, a protein with an intermolecular disulfide bridge. This mutant was exposed to Pronase E protease preparation as well as to proteases extracted from ruminal microbes. It was found that in both cases, MB-1-Cys dimer had a better resistance to proteolytic degradation than MB-1. Denaturation and hydrophobic dye binding studies revealed that this enhanced stability was not owing to conformational stabilization, but rather to changes in surface exposure as a consequence of dimerization. In particular, it was found that binding of ANSA to MB-1-Cys dimer was comparable to that observed for native, compact, natural proteins. We discuss the implications of these results for the design of transgenic protein production systems.