Novel scoring tool of hypoxemic respiratory failure and pulmonary hypertension for defining severity of persistent pulmonary hypertension of newborn

OBJECTIVE

To obtain preliminary validity data for a hypoxemic respiratory failure/pulmonary hypertension (HRF/PH) score for classifying persistent pulmonary hypertension of the newborn (PPHN).

STUDY DESIGN

Retrospective chart review of 100 consecutive neonates admitted to a Children's hospital from 2016-2021 with PPHN, gestational age ≥34 weeks, and echocardiograms in the first week. We assessed the correlation between HRF/PH score and short-term outcomes using linear and logistic regressions.

RESULTS

HRF/PH scores ranged 2-12 (mean 8.5), and were classified mild (0-5), moderate (6-10), and severe (11-15), with 6%, 77% and 17% infants in respective categories. HRF/PH score category correlated with invasive ventilation, nitric oxide, high frequency ventilation, vasoactive infusions, extracorporeal life support and death. HRF/PH score category did not correlate with duration of support or length of stay.

CONCLUSION

The HRF/PH score offers a promising representation of disease severity for PPHN. The tool requires further validation in prospective studies and evaluation for long-term outcomes.

Acute Bowel Ischemia in a Premature Neonate with Miller-Dieker Syndrome and Anomalous Right Coronary Artery From the Pulmonary Artery

Miller-Dieker syndrome (MDS) is a rare disease characterized by type I lissencephaly, craniofacial dysmorphisms, intellectual disability, seizures, and death in early childhood. We report a case of a premature infant with MDS with an anomalous right coronary artery from the pulmonary artery who developed sudden bowel ischemia. This case prompts the reconsideration of cardiovascular involvement in patients with MDS. In addition, this review highlights key clinical features and reviews the critical manifestations of MDS that persist into childhood. [Pediatr Ann. 2023;52(8):e283-e291.].

NAFTNet retrospective report on the treatment of anti-Ro/SSA mediated fetal heart block with dexamethasone

BACKGROUND

Complete atrioventricular block (CAVB) is a complication of maternal antibody positivity and treatment of fetal disease is controversial in terms of efficacy and safety. We hypothesized that dexamethasone treatment for fetal anti-Ro/SSA antibody-mediated cardiac disease leads to better pregnancy outcomes than expectant management.

METHODS

A retrospective multi-center cohort study of anti-Ro/SSA antibody positive pregnancies with fetal conduction disease reported by participating North American Fetal Therapy Network (NAFTNet) centers between January 2010 and December 2018. The primary outcomes included: fetal death, oligohydramnios, growth restriction, preterm delivery, and new maternal comorbidities. Secondary outcomes included: pacemaker prior to 28 days, transplantation, and neonatal death in maternal/fetal dyads treated with dexamethasone versus not.

RESULTS

In 127 anti-Ro/SSA positive pregnancies, 98 were treated with dexamethasone and 29 were not. Of those treated, 61/96 (63.5%) met the primary outcome including 45/91 (49.4%) premature deliveries; 20 mothers developed comorbidities during treatment (fetal death 5, 10 growth restriction, 14 oligohydramnios, two new/worsening gestational diabetes). In the untreated group, 15/25 (60%) met the primary outcome including 11/22 (50%) premature deliveries and four mothers developing comorbidities during their pregnancy (fetal death 3, one growth restriction, one new onset maternal hypertension). Regarding secondary outcomes, 37/96 (43%) treated fetuses required a pacemaker or died by 28 days, while untreated 13/25 (52%) required pacemaker placement, died prior to 28 days or required listing for transplantation. Excluding terminations, survival without transplant was 17 (68%) in untreated and 85 (89%) in treated patients (p<.01).

CONCLUSIONS

While the use of dexamethasone in anti-Ro/SSA positive pregnancies is associated with a high rate of poor pregnancy outcomes, there was an unexpected similarly high rate in untreated positive pregnancies. This suggests that the maternal disease itself is influencing pregnancy complications independent of dexamethasone. Our data, which show that treatment decreases neonatal morbidity and overall mortality without increasing overall pregnancy complications, warrant further study.

Multi-Institutional Practice-Patterns in Fetal Congenital Heart Disease Following Implementation of a Standardized Clinical Assessment and Management Plan

Background

Prenatal diagnosis of congenital heart disease has been associated with early‐term delivery and cesarean delivery (CD). We implemented a multi‐institutional standardized clinical assessment and management plan (SCAMP) through the University of California Fetal‐Maternal Consortium. Our objective was to decrease early‐term (37–39 weeks) delivery and CD in pregnancies complicated by fetal congenital heart disease using a SCAMP methodology to improve practice in a high‐risk and clinically complex setting.

Methods and Results

University of California Fetal‐Maternal Consortium site‐specific management decisions were queried following SCAMP implementation. This contemporary intervention group was compared with a University of California Fetal‐Maternal Consortium historical cohort. Primary outcomes were early‐term delivery and CD. A total of 496 maternal–fetal dyads with prenatally diagnosed congenital heart disease were identified, 185 and 311 in the historical and intervention cohorts, respectively. Recommendation for later delivery resulted in a later gestational age at delivery (38.9 versus 38.1 weeks, P=0.01). After adjusting for maternal age and site, historical controls were more likely to have a CD (odds ratio [OR],1.8; 95% CI, 2.1–2.8; P=0.004) and more likely (OR, 2.1; 95% CI, 1.4–3.3) to have an early‐term delivery than the intervention group. Vaginal delivery was recommended in 77% of the cohort, resulting in 61% vaginal deliveries versus 50% in the control cohort (P=0.03). Among pregnancies with major cardiac lesions (n=373), vaginal birth increased from 51% to 64% (P=0.008) and deliveries ≥39 weeks increased from 33% to 48% (P=0.004).

Conclusions

Implementation of a SCAMP decreased the rate of early‐term deliveries and CD for prenatal congenital heart disease. Development of clinical pathways may help standardize care, decrease maternal risk secondary to CD, improve neonatal outcomes, and reduce healthcare costs.

Revisiting the utility of technical performance scores following tetralogy of Fallot repair

OBJECTIVE

Although an important quality metric, current technical performance scores may not be generalizable and may omit operative factors that influence outcomes. We examined factors not included in current technical performance scores that may contribute to increased postoperative length of stay, major complications, and cost after primary repair of tetralogy of Fallot.

METHODS

This is a retrospective single site study of patients younger than age 2 years with tetralogy of Fallot undergoing complete repair between 2007 and 2015. Medical record data and discharge echocardiograms were reviewed to ascertain component and composite technical performance scores. Primary outcomes included postoperative length of stay, major complications, and total hospital costs. Multivariable logistic and linear regression identified determinants of each outcome.

RESULTS

Patient population (n = 115) had a median postoperative length of stay of 8 days (interquartile range, 6-10 days), and a median total cost of $71,147. Major complications occurred in 33 patients (29%) with 1 death. Technical performance scores assigned were optimum in 28 patients (25%), adequate in 59 patients (52%), and inadequate in 26 patients (23%). Neither technical performance score components nor composite scores were associated with increased postoperative length of stay. Optimum or adequate repairs versus inadequate had equal risk of a complication (P = .79), and equivalent mean total cost ($100,000 vs $187,000; P = .25). Longer cardiopulmonary bypass time per 1-minute increase (P < .01) was associated with longer postoperative length of stay and reintervention (P = .02). The need to return to bypass also increased total cost (P < .01).

CONCLUSIONS

Current tetralogy of Fallot technical performance scores were not associated with selected outcomes in our postoperative population. Although returning to bypass and bypass length are not included as components in the current score, these are important factors influencing complications and resource use in our population. Revisions anticipated from a prospective trial should consider including these variables.

The Fetus with Ectopia Cordis: Experience and Expectations from Two Centers

Ectopia cordis (EC) is a rare congenital anomaly often associated with congenital heart disease (CHD). There is a lack of contemporary information on EC diagnosed prenatally. We sought to combine the experiences of two regional referral centers in order to evaluate current outcomes for EC. Clinical, echocardiographic features and perinatal outcomes of fetuses with EC managed at two large cardiac centers from 1995 to 2014 were retrospectively reviewed. Seventeen fetuses with EC were diagnosed at a median gestational age of 23 weeks (range 17-36). There were 6 thoracic EC and 11 thoracoabdominal. Fifteen had associated CHD: 10 conotruncal defects, 2 tricuspid atresia, 1 aortic stenosis, 1 atrial septal defect, and 1 atrioventricular septal defect. There were 2 terminations of pregnancy, 2 fetal deaths, 2 lost to follow-up, and 11 live born. Mean gestational age at birth was 36.4 weeks (range 26-39). Three patients died shortly after birth with comfort care, and 8 were actively managed. Six patients underwent postnatal cardiac intervention and are currently alive with a mean follow-up of 7.3 years (range 1.4-11.4), 2 of them with chronic dependency on ventilatory support. Two patients without CHD died after attempted chest closure. When diagnosed in utero, a high proportion of pregnancy termination or fetal demise is expected. In our cohort, conotruncal anomalies were the most common associated CHD. Though mortality in actively managed patients was not as high as previously reported, and cardiac surgical intervention may be achieved, EC is still associated with high mortality and significant long-term morbidity.

Prevalence of deficient retro-aortic rim and its effects on outcomes in device closure of atrial septal defects

Deficient retro-aortic rim is of concern as a risk factor for aortic erosion after device closure of atrial septal defects (ASD). However, its prevalence and contribution to technical failure and adverse outcomes have not been delineated. A single-center retrospective cohort study of children and adults undergoing cardiac catheterization for device occlusion of ASD from 1 January 1999 to 1 April 2012 was performed. Risk factors for technical failure and early adverse outcome were assessed using multivariate logistic regression. During the study period, 445 consecutive subjects with a median age of 5.9 years (range, 0.8-80 years) underwent catheterization. Of the subjects with reviewable echocardiograms, 60 % had deficient retro-aortic rim. No attempt at device closure was made for 3.6 % of the subjects. Of the remaining 429 subjects, 96 % underwent successful device occlusion. Major early adverse events occurred in 1.2 % (95 % confidence interval 0.4-2.7 %) of the cases, all of them either device embolization or malposition. Deficient retro-aortic rim was not a risk factor for composite outcome of technical failure or early major adverse event. No deaths, late reinterventions, or erosion events occurred during 2,395 total person-years (median, 5.8 years) of follow-up evaluation. Deficient retro-aortic rim was associated with increased risk of device impingement on the aorta, but no association was seen between device impingement or deficient retro-aortic rim and the development of new/progressive aortic insufficiency. Deficient retro-aortic rim is highly prevalent but did not increase the risk of adverse outcomes. Its contribution to the risk of aortic erosion could not be addressed by this study.

The genital tract immune milieu: an important determinant of HIV susceptibility and secondary transmission

HIV is generally sexually acquired across the genital or rectal mucosa after exposure to the genital secretions of an HIV-infected partner. Most exposures to HIV do not result in infection, likely due to protection afforded by an intact mucosal epithelium, as well as by innate and adaptive mucosal immune factors present in the genital tract. Another important mucosal determinant of transmission may be the number and activation status of potential HIV target cells, including CCR5/CD4+ T cells and DC-SIGN+ dendritic cells. The simultaneous presence of other genital infections, including classical sexually transmitted infections (STIs), can enhance HIV susceptibility either by breaching the epithelial barrier, recruiting HIV target cells to the genital tract, or by generating a pro-inflammatory local immune milieu. In HIV-infected individuals, genital co-infections increase HIV levels in the genital secretions, thereby increasing secondary sexual transmission. Co-infections that act as important HIV cofactors include human cytomegalovirus (CMV), Herpes simplex virus type 2 (HSV2), Neisseria gonorrhoeae and many others. Strategies focused on genital co-infections, such as vaccines, microbicides and suppressive therapy, are feasible in the short term and have the potential to curb the pandemic.

Negative mucosal synergy between Herpes simplex type 2 and HIV in the female genital tract

OBJECTIVE

There is substantial epidemiological evidence that infection by Herpes simplex virus type 2 (HSV2) enhances both HIV susceptibility and subsequent sexual transmission. Both infections are extremely common in female sex workers (FSWs) in sub-Saharan Africa, and up to 80% of new HIV infections in urban men in the region are acquired via transactional sex. The present study aimed to elucidate the mucosal immune interactions between HIV and HSV2 in the genital tract.

METHODS

Endocervical immune cell populations, cytokine/chemokine protein levels in cervico-vaginal secretions and cervical immune gene expression profiles were measured in a well-defined cohort of HIV-infected and uninfected Kenyan FSWs. Associations between the genital immune milieu and infection by and/or shedding of common genital co-pathogens were examined.

RESULTS

HIV-infected FSWs were much more likely to be infected by HSV2, and to shed HSV2 DNA in the genital tract. There was also a profound negative 'mucosal synergy' between these viruses. In HIV uninfected FSWs, HSV2 infection was associated with a ten-fold increase in cervical immature dendritic cells (iDC) expressing DC-SIGN, and a three-fold increase in cervical CD4+ T cells expressing CCR5. HIV infection was associated with iDC depletion in the cervix, and with increased HSV2 genital reactivation, which in turn was associated with HIV shedding levels.

CONCLUSIONS

The findings suggest a mucosal vicious circle in which HSV2 infection increases HIV target cells in the genital mucosa, subsequent HIV infection impairs HSV2 mucosal immune control, and local HSV2 reactivation enhances both HSV2 and HIV transmission.

Expansion of HIV-specific CD4+ and CD8+ T cells by dendritic cells transfected with mRNA encoding cytoplasm- or lysosome-targeted Nef

Transfection with synthetic mRNA is a safe and efficient method of delivering antigens to dendritic cells for immunotherapy. Targeting antigens to the lysosome can sometimes enhance the CD4+ T-cell response. We transfected antigen-presenting cells (APCs) with mRNA encoding Gag-p24 and cytoplasmic, lysosomal, and secreted forms of Nef. Antigen-specific cytotoxic T cells were able to lyse the majority of transfected targets, indicating that transfection was efficient. Transfection of APCs with a Nef construct bearing lysosomal targeting signals produced rapid and prolonged antigen presentation to CD4+ and CD8+ T cells. Polyclonal CD4+ and CD8+ T-cell lines recognizing multiple distinct epitopes were expanded by coculture of transfected dendritic cells with peripheral blood mononuclear cells from viremic and aviremic HIV-infected subjects. Importantly, lysosome-targeted antigen drove a significantly greater expansion of Nef-specific CD4+ T cells than cytoplasmic antigen. The frequency of recognition of CD8 but not CD4 epitopes by mRNA-expanded T cells was inversely proportional to sequence entropy and was similar to ex vivo responses from a large chronic cohort. Thus human dendritic cells transfected with mRNA encoding lysosome-targeted HIV antigen can expand a broad, polyclonal repertoire of antiviral T cells, offering a promising approach to HIV immunotherapy.

A multicenter controlled trial of fetal pulse oximetry in the intrapartum management of nonreassuring fetal heart rate patterns

OBJECTIVE

Recent developments permit the use of pulse oximetry to evaluate fetal oxygenation in labor. We tested the hypothesis that the addition of fetal pulse oximetry in the evaluation of abnormal fetal heart rate patterns in labor improves the accuracy of fetal assessment and allows safe reduction of cesarean deliveries performed because of nonreassuring fetal status.

STUDY DESIGN

A randomized, controlled trial was conducted concurrently in 9 centers. The patients had term pregnancies and were in active labor when abnormal fetal heart rate patterns developed. The patients were randomized to electronic fetal heart rate monitoring alone (control group) or to the combination of electronic fetal monitoring and continuous fetal pulse oximetry (study group). The primary outcome was a reduction in cesarean deliveries for nonreassuring fetal status as a measure of improved accuracy of assessment of fetal oxygenation.

RESULTS

A total of 1010 patients were randomized, 502 to the control group and 508 to the study group. There was a reduction of >50% in the number of cesarean deliveries performed because of nonreassuring fetal status in the study group (study, 4. 5%; vs. control, 10.2%; P =.007). However, there was no net difference in overall cesarean delivery rates (study, n = 147 [29%]; vs. control, 130 [26%]; P = .49) because of an increase in cesarean deliveries performed because of dystocia in the study group. In a blinded partogram analysis 89% of the study patients and 91% of the control patients who had a cesarean delivery because of dystocia met defined criteria for actual dystocia. There was no difference between the 2 groups in adverse maternal or neonatal outcomes. In terms of the operative intervention for nonreassuring fetal status, there was an improvement in both the sensitivity and the specificity for the study group compared with the control group for the end points of metabolic acidosis and need for resuscitation.

CONCLUSION

The study confirmed its primary hypothesis of a safe reduction in cesarean deliveries performed because of nonreassuring fetal status. However, the addition of fetal pulse oximetry did not result in an overall reduction in cesarean deliveries. The increase in cesarean deliveries because of dystocia in the study group did appear to result from a well-documented arrest of labor. Fetal pulse oximetry improved the obstetrician's ability to more appropriately intervene by cesarean or operative vaginal delivery for fetuses who were actually depressed and acidotic. The unexpected increase in operative delivery for dystocia in the study group is of concern and remains to be explained.

Studies on the in vitro assembly of a beta 1-40: implications for the search for a beta fibril formation inhibitors

The progressive deposition of the amyloid beta peptide (Abeta) in fibrillar form is a key feature in the development of the pathology in Alzheimer's disease (AD). We have characterized the time course of Abeta fibril formation using a variety of assays and under different experimental conditions. We describe in detail the morphological development of the Abeta polymerization process from pseudo-spherical structures and protofibrils to mature thioflavin-T-positive/Congo red-positive amyloid fibrils. Moreover, we structurally characterize the various polymorphic fibrillar assemblies using transmission electron microscopy and determine their mass using scanning transmission electron microscopy. These results provide the framework for future investigations into how target compounds may interfere with the polymerization process. Such substances might have a therapeutic potential in AD.

Comparison of the modified biophysical profile to a "new" biophysical profile incorporating the middle cerebral artery to umbilical artery velocity flow systolic/diastolic ratio

OBJECTIVES

The objective of this study was to determine whether the addition of the middle cerebral to umbilical artery systolic/diastolic velocity waveform ratio to the modified biophysical profile would improve perinatal outcome in patients at high risk.

STUDY DESIGN

A prospective, randomized outcome study of patients referred to the perinatal laboratory for antenatal surveillance was undertaken. Six hundred sixty-five patients were randomized to two antenatal surveillance protocols: group 1, modified biophysical profile; and group 2, modified biophysical profile plus evaluation of the middle cerebral artery to umbilical artery systolic/diastolic ratio. Patients were followed up serially and neonatal outcome data including gestational age at delivery, birth weight, incidence of cesarean section delivery for fetal distress, admission to the neonatal intensive care unit, days in the neonatal intensive care unit, and the presence of significant neonatal morbidity were tabulated.

RESULTS

The total population showed no statistical difference in outcome parameters between groups 1 and 2. However, a subgroup of patients evaluated for suspected uteroplacental insufficiency did show a significant reduction in caesarean section for fetal distress in group 2 patients.

CONCLUSIONS

In a subgroup of patients at risk for uteroplacental insufficiency, the addition of the middle cerebral/umbilical artery ratio to an antenatal surveillance protocol should be expected to improve perinatal outcome.

Treatment of acardiac twinning

BACKGROUND

The twin reversed-arterial-perfusion sequence is a complication of monochorionic twin pregnancies characterized by the hemodynamic dependence of a "recipient" twin from a "pump" twin. The recipient twin exhibits lethal abnormalities including acardia and acephaly. The pump twin has a mortality rate of 50% as a result of high-output heart failure.

CASE

The blood supply to an acardiac-acephalus twin was interrupted at 24 weeks' gestation using endoscopic laser coagulation. The co-twin was delivered at 35 weeks and had an uneventful neonatal course following correction of a persistent patent ductus arteriosus. Review of the literature reveals 22 cases of acardiac twinning treated with invasive procedures, seven of them using endoscopic laser coagulation. Pump twin mortality with fetal surgery was 13.6% in comparison with 50% mortality with expectant management (P < .001).

CONCLUSION

Fetal surgery is the best available treatment for acardiac twinning. Endoscopic laser coagulation at or before 24 weeks and endoscopic or sonographic guided umbilical cord ligation after this gestational age seem to be the best treatments for this condition.

Comprehensive ultrasound examination in a private perinatal practice

A retrospective review of the types of patients seen and the accuracy of the diagnosis made was undertaken for patients referred for comprehensive ultrasound examination in a large private perinatal practice. A review of the perinatal ultrasound database, neonatal intensive care database, and hospital charts was done in 1338 patients referred to the perinatal ultrasound laboratory for comprehensive ultrasound examination during a 2-year period. Accuracy of the ultrasound diagnosis and relationships between structural anomalies seen on ultrasound examination and perinatal outcome was undertaken. Positive and negative predictive values for the ultrasonic diagnosis were 82% and 98%, respectively. There were 19 (1.4%) false-positive diagnoses and 38 (2.8%) false-negative diagnoses. There was a high correlation between structural anomalies and chromosomal anomalies, with 15 of the 87 infants (17.2%) with structural anomalies also having chromosomal anomalies. The accuracy of ultrasonic diagnosis for comprehensive examinations in a large private perinatal practice compared favorably with previous reports in the literature. The information presented in this study should be helpful to obstetric centers with similar patient populations.

Umbilical cord cyst presenting as an omphalocele at 15 weeks' gestation. A case report

A small, cystic structure was identified on a routine ultrasound scan performed for dating at 15 weeks' gestation. Originally it was thought to be an omphalocele, but further examination confirmed its origin in the cord several centimeters distal to the fetus. Close scrutiny of ultrasonograms is important since technical capabilities permit high-resolution scans during early gestation.

Formation of hydroxyeicosatetraenoic acids (HETE) in blood from adults versus neonates: reduced production of 12-HETE in cord blood

Hydroxyeicosatetraenoic acids (HETE) are major arachidonic acid metabolites of a number of cells found in blood and blood vessels. These products have been implicated in physiologic responses as diverse as platelet aggregation, cell migration, and cell proliferation. Using a sensitive and specific assay, GC/selected ion monitoring after high-performance liquid chromatography separation, we have measured the levels of three HETE isomers of biologic significance 12-HETE, 15-HETE, and 5-HETE in plasma, serum and stimulated serum (formed in the presence of arachidonic acid and calcium ionophore), obtained from normal adults and cord blood from normal neonates. Whereas there were no significant differences between the two groups for 5- or 15-HETE in any of the samples, stimulated serum from adults produced 12 times as much 12-HETE when compared to cord blood. When platelets were isolated from adult and cord blood, 12-HETE production by neonatal platelets, stimulated with 10 microM arachidonic acid, was less than one-fourth that of adults. Although no role for 12-HETE in normal platelet responses has yet been established, it has been reported that those individuals with myeloproliferative syndromes who demonstrate a concomitant decrease in platelet 12-HETE synthetic ability have an increased bleeding tendency. It needs to be further evaluated if this already depressed level of 12-lipoxygenase in neonatal platelets may contribute to pathologic bleeding in those infants subjected to additional stress (such as prematurity or birth asphyxia).

Rapid development of nephrotic syndrome, hypertension, and hemolytic anemia early in pregnancy in patients with IDDM

In recent years, the prognosis for a successful pregnancy has greatly improved for women with insulin-dependent diabetes mellitus (IDDM) who are under good glycemic control and free of complications such as vascular disease and nephropathy. We report the rapid development of severe nephrotic syndrome, malignant hypertension, and microangiopathic hemolytic anemia during the first trimester of pregnancy in a 29-yr-old woman with IDDM of 18 yr duration. Our patient had no pregestational history of retinopathy or hypertension and only minimal proteinuria. Significant improvement in blood glucose levels had been achieved over the 6 mo before conception. Kidney biopsy performed before the termination of pregnancy at 10 wk gestation revealed diabetic nephropathy. No other etiology for her renal disease could be found. An arteriole was noted to have entrapped red blood cell fragments and platelet thrombi, revealing the probable source of her hemolytic process. By 8 wk postpartum, her nephrotic syndrome and hemolysis had completely resolved. At 3 mo postgestation, the patient's hypertension was still present but less severe. Her serum creatinine has continued to decrease toward normal. This is the first report of a woman with IDDM in White's classification C who developed a toxemia-like syndrome during the first trimester of pregnancy, attributable to the underlying diabetic state.

Effect of amniotic fluid on platelet thromboxane production

We have studied the effect of amniotic fluid on thromboxane A2 (TXA2) production as an initial step in an evaluation of the role of this metabolite as the mediator of the pulmonary hypertension that accompanies perinatal aspiration. Term amniotic fluid enhanced platelet thromboxane B2 (TXB2) production in the presence of the aggregating agents thrombin and arachidonic acid, activity being confined to the lipid fraction. Compared with a baseline production of 1.4 +/- 0.45 pmol TXB2/10(6) platelets in response to thrombin (1 U/ml), unfractionated amniotic fluid or its lipid fraction enhanced TXB2 production to 2.87 +/- 0.53 and 2.81 +/- 0.62 pmol, respectively (P less than 0.01). Values for the aqueous extract were no different from buffer control values (1.14 +/- 0.5). No enhancement of platelet TXB2 production was observed in amniotic fluid obtained at 15 to 17 weeks. Similar activity was observed with either adult or neonatal platelets. This thromboxane enhancing property of amniotic fluid appears to be distinct from its thrombin generating property. Following perinatal aspiration, in situ production of thrombin and proaggregatory TXA2 could recruit more platelets, enhance local TXA2 production, and be responsible for the platelet thrombi that have been documented at autopsy in the pulmonary microcirculation in infants with perinatal aspiration syndrome.

Effect of fetal intravascular 4-aminoantipyrine infusions on myometrial activity (contractures) at 125 to 143 days' gestation in the pregnant sheep

Myometrial activity of low amplitude and long duration--contractures--is present throughout gestation in the pregnant ewe and other species. This activity differs from the contractions of labor and delivery. Between 125 and 143 days' gestation, 4-aminoantipyrine infused into the fetus at rates that produced maternal uterine vein plasma concentrations of 4-aminoantipyrine of 5.95 +/- 1.23 (mean +/- SEM, n = 5) mg X 100 ml-1 markedly depressed both total myometrial electromyographic activity to 28.6% and frequency of contractures to 30.5% of preinfusion values. By 60 minutes of infusion, maternal uterine vein plasma 13,14-dihydro-15-keto prostaglandin F2 alpha concentration was reduced to 14% of the resting level. Two conclusions were drawn from this study. First, prostaglandins are involved in the regulation of contractures. Second, when infusions of 4-aminoantipyrine are used to quantify uterine or umbilical blood flow, the possibility exists that changes will occur in physiologic systems that are modified by prostaglandins.