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Biomedical subjects

H C Wallenburg

Publications and source records attributed to H C Wallenburg.

At least 37 records · Page 2Linked to original sources
PubMed1995

Sensitivity of ovine myometrial tissue to various eicosanoids in vitro.

The sensitivity of sheep myometrial tissue to prostaglandin F2 alpha (PGE2 alpha), PGE2, the thromboxane analog U-44069, and leukotrienes C4 (LTC4) and LTD4 was investigated in a superfusion system. Tissues were obtained from eight oophorectomized ewes, with or without pretreatment with estradiol-17 beta. After equilibration, spontaneous activity was abolished by adding indomethacin to the superfusion fluid. The dose needed to induce a contraction with a peak level of 50% of the median peak level of spontaneous contractions increased from PGE2 to PGF2 alpha, U-44069, LTC4, and LTD4. The differences between the doses required were significant for all compounds, except between LTC4 and LTD4. Estradiol-17 beta pretreatment caused an increase in the required dose of PGF2 alpha. The results of this study do not support the hypothesis that leukotrienes are involved in the regulation of myometrial activity.

Animals↗
PubMed1995

Maternal and perinatal outcome of temporizing management in 254 consecutive patients with severe pre-eclampsia remote from term.

OBJECTIVE: To assess maternal and perinatal outcomes of expectant management with plasma volume expansion and pharmacologic vasodilatation in patients with severe pre-eclampsia remote from term. STUDY DESIGN: All women with severe pre-eclampsia between 20 and 32 weeks' gestation, not in labor and with a live, single fetus admitted to the University Hospital Rotterdam from 1985 to 1993 were managed with the intention to prolong gestation. Treatment consisted of correction of the maternal circulation with vasodilatation by means of dihydralazine and plasma volume expansion under central hemodynamic monitoring. Primary end-points of the study were prolongation of gestation, maternal antepartum and postpartum complications, and fetal and neonatal outcome. RESULTS: Two-hundred fifty-four patients were included. The median prolongation of pregnancy was 14 (range 0-62) days. Hemodynamic treatment was associated with marked objective and subjective improvement in maternal condition. Complications of central hemodynamic monitoring were not observed. Perinatal mortality was 20.5%. CONCLUSION: Expectant management with plasma volume expansion and pharmacologic vasodilatation under central hemodynamic monitoring of the maternal circulation may delay delivery and enhance fetal maturity and does not appear to be associated with an increased risk of maternal morbidity and mortality.

Adolescent↗
PubMed1995

Low-dose aspirin therapy in obstetrics.

The results of four large controlled clinical trials, encompassing over 13,000 pregnant women, indicate that low-dose aspirin is of benefit in the prevention of pre-eclampsia in women at high risk. The preventive effect on fetal growth retardation seems to be small, and no therapeutic benefits could be established. Low-dose aspirin appears to be safe for mother, fetus, and neonate.

Aspirin↗
PubMed1995

Expectant management of twin pregnancy with single fetal death.

OBJECTIVE: To evaluate the course and outcome of expectantly managed twin pregnancies with single fetal death in the second half of gestation. DESIGN: Case-controlled study of 29 consecutive pregnancies from 1973 to 1993, with sonographic evidence of a twin at 20 weeks gestation with antenatal demise later in pregnancy, matched for maternal parity with 58 twin pregnancies without fetal death and delivered in the same year as the index case. Outcome measures included the incidence of complications of pregnancy, gestational age and mode of delivery, placentation, and perinatal outcome. SETTING: University Hospital Rotterdam. RESULTS: The frequency and severity of pregnancy-induced hypertensive disorders was significantly higher in the study group than in controls. We found no differences between the study group and controls with regard to median gestational age at delivery (33 weeks versus 34 weeks) and median birthweight of liveborn infants (1880 g versus 2160 g). No consumptive coagulopathy was apparent in our 29 patients. The main cause of neonatal death was prematurity; multicystic encephalomalacia was not observed. CONCLUSIONS: Our results support expectant management in twin pregnancies complicated by single fetal death.

Adult↗
PubMed1995

Temporising management of severe pre-eclampsia with and without the HELLP syndrome.

OBJECTIVE: To test the null hypothesis that the course and outcome of pregnancy in patients with severe pre-eclampsia receiving temporising haemodynamic treatment does not depend on the presence or absence of the syndrome of haemolysis, elevated liver enzymes, and a low platelet count (HELLP). DESIGN: A case-controlled study. SETTING: High risk obstetric unit, University Hospital Rotterdam-Dijkzigt, Rotterdam. SUBJECTS: One hundred and twenty-eight consecutive pre-eclamptic patients with HELLP, gestational age less than 34 weeks, matched for maternal and gestational age with 128 pre-eclamptic patients without HELLP. INTERVENTION: Both groups were treated with volume expansion and pharmacologic vasodilatation under invasive haemodynamic monitoring with the aim of prolonging gestation and enhancing fetal maturity. MAIN OUTCOME MEASURES: Maternal and perinatal outcome in patients with and without HELLP. RESULTS: Except for variables pertaining to HELLP, clinical and laboratory data and median prolongation of pregnancy did not differ between both groups. Complete reversal of HELLP occurred in 43% of patients. Perinatal mortality was 14.1% in HELLP patients and 14.8% in patients without HELLP. No maternal complications occurred. CONCLUSION: We cannot reject the null hypothesis. Our data do not support a general recommendation of prompt termination of pregnancy in HELLP. Temporising treatment may improve fetal and neonatal as well as maternal outcome.

Adolescent↗
PubMed1995

Anaerobic threshold and respiratory compensation in pregnant women.

In an effort to explore why CO2 output (VCO2) at peak exercise is lower during pregnancy than postpartum despite little change in the peak O2 uptake (VO2), we determined the VCO2/VO2 relationship during rapidly incremental exercise and estimated the anaerobic threshold (AT) and the respiratory compensation (RC) point. We measured heart rate, VO2, VCO2, and minute ventilation (VE) at rest and during cycle exercise tests with rapidly increasing exercise intensities until maximal effort in 33 volunteers at 16-, 25-, and 35-wk gestation and postpartum. Through modification of the V-slope method, we estimated the AT and RC point for each test by nonlinear regression analysis in a three-dimensional space (defined by VE, VO2, and VCO2) for a line assumed to have two breakpoints; we found a good fit for all tests. The AT and RC points were found at exercise intensities of approximately 50 and 80% peak VO2, respectively, with no significant differences between test periods. VE was significantly higher during pregnancy than during postpartum at rest and throughout incremental exercise. A lower peak VCO2 relative to peak VO2 during pregnancy compared with postpartum was reflected by a more shallow slope of VCO2 vs. VO2 above the AT point. This suggests that during pregnancy the buffering of lactic acid is reduced.

Adult↗
PubMed1995

A comparison between the haemodynamic effects of oral nifedipine and intravenous dihydralazine in patients with severe pre-eclampsia.

OBJECTIVE: To compare the effects of a single oral dose of nifedipine with those of intravenous dihydralazine on central haemodynamics in pregnant women with severe pre-eclampsia. DESIGN: A prospective comparative study. SETTING: The High Risk Obstetric Unit, University Hospital Rotterdam Dijkzigt, Rotterdam. SUBJECTS: Twenty patients with severe pre-eclampsia between 27 and 35 weeks gestation with normal cardiac filling pressures and without fetal distress. INTERVENTIONS: A pulmonary artery thermodilution catheter and a radial artery line were placed. Ten patients chewed a 10-mg capsule of nifedipine and 10 patients received dihydralazine by intravenous infusion at a rate of 1-3 mg/h. Arterial pressures, heart rate, cardiac output and pulmonary capillary wedge pressure were determined before and after drug administration. Fetal condition was continuously monitored by cardiotocography. RESULTS: The reduction in arterial blood pressure obtained with both drugs was similar, and was associated with a similar rise in heart rate and cardiac output and a similar reduction in systemic vascular resistance. Pulmonary capillary wedge pressures decreased significantly less with nifedipine than with dihydralazine. Signs of fetal distress occurred in none of the nifedipine-treated patients, but in five of the patients treated with dihydralazine. CONCLUSION: From the haemodynamic viewpoint nifedipine seems to be a useful agent in the treatment of hypertensive emergencies in pregnancy.

Administration, Oral↗
PubMed1994

Effects of labor and delivery on fibrinolysis.

Because timing of sampling is crucial in an investigation of the effects of labor and delivery on fibrinolysis we conducted a study of fibrinolytic markers in plasma of 10 healthy multiparous women in whom labor was induced, which allowed standardization of sampling times in relation to the course of labor and delivery. Blood samples were taken 5 min before the start of oxytocin infusion, at full cervical dilatation, and within 5 min after delivery of the placenta. A sample of mixed free flowing cord blood was obtained after delivery with the placenta in situ. Variables determined were tissue-type plasminogen-activator (t-PA) and the plasminogen activator inhibitors type 1 (PAI-1) and type 2 (PAI-2). The only significant change between the beginning of the induction of labor and the end of the first stage of labor was a rise in t-PA antigen (P = 0.01). All variables, except PAI-2 antigen, changed significantly after delivery of the placenta: t-PA antigen and activity showed a rise (P < 0.05), accompanied by a fall in PAI-1 antigen and activity (P < 0.01). T-PA activity in cord plasma was higher (P < 0.01) in comparison with maternal plasma concentrations at the end of the first stage of labor, t-PA antigen levels were similar, and PAI-1 antigen and activity and PAI-2 antigen were lower in cord plasma (P < 0.001). Our study shows that activation of the maternal fibrinolytic system can already be detected during labor, with a marked further increase in fibrinolytic potential after placental separation.

Adult↗
PubMed1994

Effects of estrogen treatment and inhibition of prostanoid synthesis on myometrial activity and gap junction formation in the oophorectomized ewe.

The objective was to elucidate the functional relationship between estradiol-induced changes in myometrial activity, uterine prostanoid synthesis, and gap junction formation in vivo. The study design was as follows. The effects of inhibition of prostanoid synthesis with naproxen on formation of gap junctions and coordination of electrical and mechanical myometrial activity induced by estradiol-17 beta were investigated in 6 chronically instrumented oophorectomized ewes. Prostanoid metabolites were measured in arterial and uterine venous plasma. Myometrial biopsies were obtained to determine gap junction area. The results were that intraarterial administration of 0.1 mg of estradiol-17 beta was followed by a significant increase in maximum rate of rise of the intrauterine pressure cycles and a significant decrease in conduction time of bursts of electrical activity; this response was not altered by pharmacologic inhibition of uterine prostanoid synthesis using naproxen. Estradiol administration during continuous naproxen infusion increased gap junction area. The conclusion is that improved coordination of myometrial activity and formation of myometrial gap junctions induced by estradiol is not mediated by prostaglandins.

6-Ketoprostaglandin F1 alpha↗
PubMed1994

Perinatal results of hemodynamic and conservative temporizing treatment in severe pre-eclampsia.

OBJECTIVE: To evaluate maternal and perinatal outcome of hemodynamic temporizing management in severe pre-eclampsia. DESIGN: Study group of 57 pre-eclamptic women, gestational age 35 weeks or less, treated with plasma volume expansion and vasodilatation under invasive hemodynamic monitoring, retrospectively matched with a control group treated in another center without volume expansion and invasive monitoring. RESULTS: In both groups pregnancy was prolonged with 10-11 days. Maternal morbidity was low in both groups. No complications of hemodynamic monitoring were observed. Perinatal mortality was not significantly different between the study group (7.1%) and the control group (14.3%). SGA-infants were significantly less frequent in the study group (9%) than in controls (33%). CONCLUSION: Temporizing treatment of patients with early severe pre-eclampsia, with or without plasma volume expansion and invasive hemodynamic monitoring, may reduce neonatal mortality and morbidity. The difference in birthweight between study group and control group may be an effect of the therapy or may be caused by selection bias. The perinatal outcome in the study group suggests that there may be a subgroup of patients who might benefit from hemodynamic treatment.

Cerebral Hemorrhage↗
PubMed1994

Detection of Bacteroides fragilis endotoxin in amniotic fluid by counterimmunoelectrophoresis.

The ability of counter immunoelectrophoresis (CIE) to detect Bacteroides fragilis endotoxin in amniotic fluid in small concentrations was evaluated. A method was developed which, in combination with ultrafiltration, permits detection of B. fragilis endotoxin in amniotic fluid in a concentration of 40 ng/ml or more. The sensitivity threshold was reduced to 2 ng/ml by using a highly reactive IgG-fraction isolated from rabbit anti-B. fragilis IPL E 323 antiserum.

Amniotic Fluid↗
PubMed1994

Poor sensitivity of the fifty-gram one-hour glucose screening test for hyperglycemia.

To determine the sensitivity and specificity of the 50-g 1-h glucose screening test (GST) for hyperglycemia established in a home-monitored glucose profile (HGP) from blood sampled 1 h after each of the main meals on the following day, we prospectively studied 415 pregnant women at increased risk for gestational diabetes and compared 1 GST with 1 HGP. At the commonly recommended GST threshold of 7.8 mmol/l and an HGP threshold of 7.0 mmol/l, the sensitivity of the GST was 27%, the specificity 89%, and the likelihood ratio for a positive test 2.4. Therefore, we conclude that the 50-g 1-h glucose screening test discriminates poorly between pregnant women with and without postprandial hyperglycemia.

Blood Glucose↗
PubMed1994

Perinatal listeriosis in a Dutch woman returning from holiday in France.

A case is reported of perinatal infection and fetal death due to Listeria monocytogenes serotype 4B in a 28-weeks pregnant woman, who had spent her holiday in an area in France where an epidemic outbreak of listeriosis had occurred. Sero- and phage-typing combined with sensitive DNA-typing demonstrated that the Listeria was identical to the strain responsible for the outbreak in France. Although listeriosis appears to be an uncommon cause of perinatal infection, practicing obstetricians should be aware of the possibility.

Adult↗
PubMed1994

Glucagon stimulation test: assessment of beta-cell function in gestational diabetes mellitus.

OBJECTIVE: Because women with gestational diabetes mellitus have a risk of up to 60% for the later development of type II diabetes, we used the intravenous glucagon stimulation test to evaluate beta-cell function in pregnant women. PATIENTS: Twenty-seven pregnant women with one or more risk factors for gestational diabetes had an intravenous beta-cell stimulation test. Glucose, C-peptide and insulin levels were measured at baseline and 5, 10 and 15 min after the administration of 1 mg glucagon. The women were classified using the 75-g oral glucose tolerance test according to World Health Organization criteria. During the oral glucose tolerance test glucose, C-peptide and insulin levels were measured at baseline and at 2 h. RESULTS: Insulin and C-peptide responses were significantly lower in pregnant women with impaired glucose tolerance and diabetes compared with women with normal glucose tolerance. CONCLUSION: This study shows gradually decreasing insulin secretion from normal to subnormal in pregnant women without and with glucose intolerance, and diabetes mellitus, respectively.

Adult↗
PubMed1994

Ultrasound assessment of cervical dynamics during the first stage of labor.

OBJECTIVE: Assessment of cervical dynamics during the first stage of labor by a combination of ultrasound cervimetry and intrauterine tocography. METHODS: Sixty-two parturients were divided into four groups: nulliparous women in spontaneous (n = 9) or oxytocin-induced labor (n = 26), parous women in spontaneous (n = 11) or oxytocin-induced labor (n = 16). Intrauterine pressure and cervical dilatation were continuously recorded and assessed by off-line computer analysis. RESULTS: All women with spontaneous labor showed cervical responses to uterine contractions at the beginning of the recording. The first cervical response to a uterine contraction occurred at a significantly smaller dilatation in parous than in nulliparous women with induced labor (2.9 and 3.6 cm, respectively). Also, acceleration of cervical dilatation occurred at less dilatation in parous than in nulliparous women (3.4 cm and 4.8 cm, respectively), and myometrial work per cm of cervical dilatation was less in parous than in nulliparous parturients. CONCLUSIONS: The results indicate significant differences between cervical dilatation patterns in nulliparous and parous women, which may be due to structural cervical changes caused by labor and parturition. The labor patterns found were different from those originally described by Friedman (Friedman EA. Graphic analysis of labor. Am J Obstet Gynecol 1954; 68: 1568-1575), as no deceleration phases were detected. Ultrasound cervimetry is a valuable technique for the study of cervical dynamics during labor.

Adolescent↗
PubMed1994

Pregnancy-induced hypertensive disorders.

The concept that endothelial cell activation and injury constitutes the key pathogenetic event is receiving increasing support, but the causative factor or factors are, as yet, unclear. The search for a reliable and clinically useful test to identify pregnant women at risk continues. No definitive conclusions can yet be drawn as to the efficacy and safety of low-dose aspirin prophylaxis. Monitoring of maternal-fetal condition, careful consideration of maternal and perinatal risks, and a balanced decision to continue or terminate pregnancy are key elements of clinical management.

Antihypertensive Agents↗