The cellular and immunological dynamics of early and transitional human milk

Human milk is essential for infant nutrition and immunity, providing protection against infections and other immune-mediated diseases during the lactation period and beyond in later childhood. Milk contains a broad range of bioactive factors such as nutrients, hormones, enzymes, immunoglobulins, growth factors, cytokines, and antimicrobial factors, as well as heterogeneous populations of maternal cells. The soluble and cellular components of milk are dynamic over time to meet the needs of the growing infant. In this study, we utilize systems-approaches to define and characterize 62 analytes of the soluble component, including immunoglobulin isotypes, as well as the cellular component of human milk during the first two weeks postpartum from 36 mothers. We identify soluble immune and growth factors that are dynamic over time and could be utilized to classify milk into different phenotypic groups. We identify 24 distinct populations of both epithelial and immune cells by single-cell transcriptome analysis of 128,016 human milk cells. We found that macrophage populations have shifting inflammatory profiles during the first two weeks of lactation. This analysis provides key insights into the soluble and cellular components of human milk and serves as a substantial resource for future studies of human milk.

The cellular dynamics of early and transitional human breast milk

Breast milk (BM) is a complex fluid containing factors essential for infant nutrition and immunity. Breastfeeding has been shown to be protective against infections and other immune-mediated diseases during the lactation period and beyond in later childhood. This suggests that BM also imprints the neonatal immune system and influences long-term health. BM also contains populations of maternal-derived cells. Which factors in BM that are important for neonatal health and how they change during lactation have not been well-defined. In this study, we used a single-cell transcriptomic approach to identify and define cell types of early and transitional milk. We collected BM samples from mothers of infants 2–5 days (early milk) and 8–12 days (transitional milk) after delivery. We applied single-cell RNA sequencing on over 154,000 BM-derived cells. We identified 25 transcriptionally distinct populations of cells in the BM. As expected, the most abundant cells in BM were mammary epithelial cells and macrophages. Monocytes, T cells, dendritic cells, and neutrophils were also present and had a higher frequency in week 2, suggesting that some immune cells may remain abundant in the early days of lactation and slowly decline as milk matures. We also detected a small number of stem and progenitor, natural killer and B cells in the BM at a higher frequency in week 1. This work provides an atlas of the cellular component in human milk at two timepoints of lactation. In addition to cell identity and frequencies, we have also uncovered unique molecular pathways that are activated in BM cells. This work will lay the foundation for future studies of how these cells influence neonatal health.

Supported by funding from Children's Mercy Kansas City

Maternal plasma soluble neuropilin-1 is downregulated in fetal growth restriction complicated by abnormal umbilical artery Doppler: a pilot study

OBJECTIVES

Placental expression of neuropilin-1 (NRP1), a proangiogenic member of the vascular endothelial growth factor receptor family involved in sprouting angiogenesis, was recently discovered to be downregulated in pregnancies with fetal growth restriction (FGR) and abnormal umbilical artery (UA) Doppler. Soluble NRP1 (sNRP1) is an antagonist to NRP1; however, little is known about its role in normal and FGR pregnancies. This study tested the hypotheses that, first, sNRP1 would be detectable in maternal circulation and, second, its concentration would be upregulated in FGR pregnancies compared to those with normal fetal growth and this would correlate with the severity of the disease as assessed by UA Doppler.

METHODS

This was a prospective case-control pilot study of 40 singleton pregnancies (20 FGR cases and 20 uncomplicated controls) between 24 + 0 and 40 + 0 weeks' gestation followed in an academic perinatal center from January 2015 to May 2017. FGR was defined as an ultrasound-estimated fetal weight < 10^th percentile for gestational age. The control group was matched to the FGR group for maternal age and gestational age at assessment. Fetal ultrasound biometry and UA Doppler were performed using standard protocols. Maternal plasma sNRP1 measurements were performed using a commercially available ELISA.

RESULTS

Contrary to the study hypothesis, maternal plasma sNRP1 levels were significantly decreased in FGR pregnancies as compared to those with normal fetal growth (137.4 ± 44.8 pg/mL vs 166.7 ± 36.9 pg/mL; P = 0.03). However, there was no significant difference in sNRP1 concentration between the control group and FGR pregnancies that had normal UA Doppler. Plasma sNRP1 was downregulated in FGR pregnancies with elevated UA systolic/diastolic ratio (P = 0.023) and those with UA absent or reversed end-diastolic flow (P = 0.005) in comparison to FGR pregnancies with normal UA Doppler. This suggests that biometrically small fetuses without hemodynamic compromise are small-for-gestational age rather than FGR.

CONCLUSIONS

This study demonstrated a significant decrease in maternal plasma sNRP1 concentration in growth-restricted pregnancies with fetoplacental circulatory compromise. These findings suggest a possible role of sNRP1 in modulating fetal growth and its potential as a biomarker for FGR. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Pathogenesis of Preeclampsia and Therapeutic Approaches Targeting the Placenta

Preeclampsia (PE) is a serious pregnancy complication, affecting about 5–7% of pregnancies worldwide and is characterized by hypertension and damage to multiple maternal organs, primarily the liver and kidneys. PE usually begins after 20 weeks’ gestation and, if left untreated, can lead to serious complications and lifelong disabilities—even death—in both the mother and the infant. As delivery is the only cure for the disease, treatment is primarily focused on the management of blood pressure and other clinical symptoms. The pathogenesis of PE is still not clear. Abnormal spiral artery remodeling, placental ischemia and a resulting increase in the circulating levels of vascular endothelial growth factor receptor-1 (VEGFR-1), also called soluble fms-like tyrosine kinase-1 (sFlt-1), are believed to be among the primary pathologies associated with PE. sFlt-1 is produced mainly in the placenta during pregnancy and acts as a decoy receptor, binding to free VEGF (VEGF-A) and placental growth factor (PlGF), resulting in the decreased bioavailability of each to target cells. Despite the pathogenic effects of increased sFlt-1 on the maternal vasculature, recent studies from our laboratory and others have strongly indicated that the increase in sFlt-1 in PE may fulfill critical protective functions in preeclamptic pregnancies. Thus, further studies on the roles of sFlt-1 in normal and preeclamptic pregnancies are warranted for the development of therapeutic strategies targeting VEGF signaling for the treatment of PE. Another impediment to the treatment of PE is the lack of suitable methods for delivery of cargo to placental cells, as PE is believed to be of placental origin and most available therapies for PE adversely impact both the mother and the fetus. The present review discusses the pathogenesis of PE, the complex role of sFlt-1 in maternal disease and fetal protection, and the recently developed placenta-targeted drug delivery system for the potential treatment of PE with candidate therapeutic agents.

The effect of race and supplementation on maternal and umbilical cord plasma folates

OBJECTIVE

The purpose of this study is to test the hypothesis that race and supplementation affect the concentration and correlation of various folate species in maternal and umbilical cord blood.

METHODS

This is a single-center, prospective, cross-sectional cohort of cord blood samples obtained from 40 uncomplicated term pregnancies as a pilot study, following a protocol approved by the Institutional Review Board. High performance liquid chromatography mass spectrometry quantitated the following concentrations in extracted plasma samples: 5-methyltetrahydrofolate (5MTHF), 5,10-methenyl-tetrahydrofolate (5,10-MeTHF), tetrahydrofolate (THF), and unmetabolized folic acid.

RESULTS

Folate concentrations in the umbilical cord plasma were consistently higher than maternal samples for 5MTHF (p < .001), 5,10-MeTHF (p < .001), and THF (p < .001); cord blood folic acid levels, however, were lower than maternal samples (p < .03). While 5MTHF was the most prevalent folate, ratios comparing cord blood to maternal blood folates suggests a fourfold preponderance of THF in cord blood folate signature, a trend unchanged by supplementation. Prenatal supplementation increased the concentrations of 5MTHF, for both maternal (p < .01) and cord blood samples (p < .005). In comparison to the other two racial groups, African American 5MTHF concentration demonstrated a lower total folate concentration in both maternal samples and cord blood samples, in addition to a relatively blunted response to supplementation. A significantly positive correlation between maternal and cord blood 5MTHF concentration was noted in all three racial groups. Supplementation resulted in a positive correlation between maternal and cord blood 5MTHF concentrations (r = 0.85, p < .0001).

CONCLUSIONS

5MTHF is the most prevalent folate in both cord and maternal plasma, and race and supplementation primarily affect variations in maternal and fetal 5MTHF concentrations and their correlation with each other. However, the greater concentration of THF in cord blood relative to maternal blood offers preliminary insight into the importance of how folate metabolism differs in the specific context of fetal development and physiology, with greater emphasis on DNA synthesis and stability. Furthermore, supplementation appeared to not have as great an impact on African American maternal or cord blood folates, suggesting a variable benefit of current repletion strategies to certain subsets of the population. Future studies that further elucidate these differences and their impact on birth outcomes may help inform supplementation protocols that are more personalized, with greater efficacy in promoting positive perinatal outcomes.

The Zika virus and pregnancy: evidence, management, and prevention

OBJECTIVE

To comprehensively review the available evidence and existing consensus reports and guidelines regarding the pregnancy and reproductive implications of the mosquito-transmitted Zika virus (ZIKV) infection. A primary focus was to provide pertinent information to aid clinicians in the management of pregnancies at risk for, exposed to, or with confirmed ZIKV infection.

METHOD

An extensive literature review was performed using Pubmed. Practice guidelines and consensus reports were accessed from international, national, and professional organizations' websites. The clinical articles for ZIKV infection testing varied from case reports to small epidemiologic studies.

RESULTS

A ZIKV epidemic has been declared in several countries in the Americas. Fifty-two travel-associated ZIKV infection cases have been reported throughout the USA (as of February 10, 2016). The consequences of congenital fetal/newborn ZIKV infection could potentially have devastating consequences including miscarriage, fetal death, and major anomalies such as microcephaly, brain and brain-stem defects, and long-term neurologic sequelae. While not definitive, current evidence suggests the existence of nonvector-borne transmission through sexual activity with an infected male partner. For women at risk for sexual transmission, condom use is advised, especially during pregnancy.

CONCLUSION

While ZIKV infection appears to be a mild disease in the general population the potential consequences to the fetus and newborn could be profound. Management guidelines are currently evolving and will be significantly impacted as new evidence develops. It is therefore imperative that obstetric health-care providers keep abreast of this rapidly evolving information landscape that has so far characterized this outbreak.

Role of ultrasound in pre-eclampsia

Pre-eclampsia (PE), defined as de novo hypertension (>140/90 mmHg) appearing after 20 weeks of gestation accompanied by proteinuria (>0.3 g/24 h), remains a major source of perinatal growth restriction, prematurity and death worldwide. Since its introduction practitioners have increasingly utilized fetal ultrasonography for the management of pre-eclampsia. Ultrasonographic diagnostic modalities including fetal biometric growth curves, the biophysical profile and umbilical artery Doppler have been used to detect fetal growth restriction and assess fetal wellbeing, respectively. Doppler studies of the middle cerebral and uterine arteries offer additional utility in the prediction of adverse pregnancy outcomes and as a potential screening test for pre-eclampsia. The purpose of this review was to explore the developments of ultrasound technology that have been relevant to the screening, diagnosis and management of pre-eclampsia.

Evidence-based approach to umbilical artery Doppler fetal surveillance in high-risk pregnancies: an update

Antepartum fetal surveillance with Doppler ultrasound of umbilical artery has shown significant diagnostic efficacy in identifying fetal compromise in pregnancies complicated with fetal growth restriction and preeclampsia. Moreover, randomized clinical trials and their meta-analyses have shown its effectiveness in decreasing perinatal mortality (level I evidence). This is the only antepartum fetal test that has shown this level of effectiveness. There is no evidence that routine Doppler in low-risk pregnancies improves the outcome. It is recommended that umbilical artery Doppler should be the standard of practice in managing high-risk pregnancies complicated with fetal growth restriction and preeclampsia (level A recommendation). However, its use should be integrated with other current fetal monitoring tests (levels B and C recommendation). The overall management should also be guided by additional clinical considerations such as the gestational age, fetal and maternal status, and obstetrical conditions.

Male gender significantly increases risk of oxidative stress related congenital anomalies in the non-diabetic population

OBJECTIVE

Oxidative stress (OS) is an important mechanism of teratogenesis. Recent work suggests increased OS in males. We evaluated whether male gender increased the risk of cyanotic congenital heart defects (CCHD) whose development is linked to OS and other common congenital anomalies (CA) in non-diabetic pregnancies.

METHODS

CDC-National Center for Health Statistics data for 19 states in 2006 were reviewed. CCHD, anencephaly, spina bifida, congenial diaphragmatic hernia (CDH), omphalocele, gastroschisis, limb defects, cleft lip with or without cleft palate (CL/P) and isolated cleft palate were evaluated. Adjusted odds ratio (OR) (95% CI) were calculated for CA in males with females as the reference group.

RESULTS

Of 1,194, 581, cases analyzed after exclusions, 3037 (0.25%) had major CA. Males had elevated adjusted OR (95% CI) for CCHD: 1.198 (1.027, 1.397), CDH: 1.487 (1.078, 2.051), and CL/P: 1.431 (1.24, 1.651). There was a significant interaction between cigarette use and (male) fetal gender and also with maternal age in the CL/P group.

CONCLUSIONS

In non-diabetic pregnancies, male gender appears to be an independent risk factor for some types of CA believed to be associated with OS. Cigarette smoking, a well recognized source of OS only increased the risk of CL/P in males.

Umbilical artery Doppler in the assessment of fetal growth restriction

Antepartum fetal surveillance with Doppler ultrasound of umbilical artery has shown significant diagnostic efficacy in identifying fetal compromise in pregnancies complicated with fetal growth restriction (FGR). Its effectiveness in decreasing perinatal mortality has been shown by randomized clinical trials (Level I evidence). This test is the only antepartum fetal test that has shown this level of effectiveness and should be the standard of practice in managing FGR (Level A recommendation). The overall management considerations should encompass other standard fetal monitoring tests (Level B and C recommendations).

Comparison of obstetric outcomes in twin pregnancies after in vitro fertilization, ovarian stimulation and spontaneous conception

OBJECTIVE

To compare the outcomes of liveborn twin gestations conceived after in vitro fertilization (IVF) or ovarian stimulation with spontaneously conceived twin pregnancies.

METHODS

A review of all twin gestations delivered at Winthrop-University Hospital from 1 January 1999 to 31 December 2000. Women who underwent fetal reduction or had a demise of one twin were excluded. Maternal demographics, antepartum complications, mode of delivery and perinatal outcome were compared.

RESULTS

Sixty pregnancies were conceived after IVF, 34 were conceived by ovarian stimulation and 101 were spontaneously conceived. Women in the IVF group were older (p < 0.001), were more often 35 years or older (p < 0.001) and primiparous (p = 0.005). More women in the ovarian stimulation group had a poor obstetric history (p = 0.04). Spontaneous gestations had a higher incidence of monochorionic placentations (p = 0.002). There were no differences in gestational age at delivery, antepartum complications, or mode of delivery. There were fewer low-birth-weight neonates in the IVF group (odds ratio 0.59, 95% confidence interval 0.35-0.98; p = 0.03) than in the spontaneous group, but the difference disappeared when only the dichorionic pregnancies were compared. Other neonatal outcomes studied were the same among groups.

CONCLUSION

Twin gestations conceived following IVF and ovarian stimulation appear to have similar outcomes to spontaneously conceived twin gestations.

Randomized controlled trial of vaginal misoprostol versus dinoprostone vaginal insert for labor induction

OBJECTIVE

To compare the safety and efficacy of vaginal misoprostol versus dinoprostone vaginal inserts for cervical ripening and labor induction.

METHODS

Two hundred singleton gestations with an indication for cervical ripening and induction of labor were randomized to receive either 50 microg of misoprostol intravaginally every 3 h or a 10-mg dinoprostone vaginal insert every 12 h for a maximum of 24 h. Statistical analysis included Student's t test, the Mann-Whitney U test, chi2 analysis and Fisher's exact test.

RESULTS

Ninety-seven women received vaginal misoprostol while 89 women received the dinoprostone vaginal insert. Fourteen women were removed from the study after randomization. The interval from start of induction to vaginal delivery (794.5 +/-408 min vs. 1005.3 +/- 523 min; p < 0.02) was significantly shorter in the misoprostol group. Women receiving misoprostol were more likely to deliver vaginally both in < 12 h (44% vs. 12%; p < 0.0001) and < 24 h (68% vs. 38%; p < 0.001). A non-reassuring fetal heart rate tracing was the indication for 71.4% (20/28) of Cesarean deliveries in the misoprostol group compared to 40% (14/35) in the dinoprostone group (p = 0.03). There were no significant differences in neonatal outcomes.

CONCLUSION

Intravaginal misoprostol and dinoprostone are safe and effective medications for use in cervical ripening before labor induction. Misoprostol results in a shorter interval from induction to delivery. However, Cesarean delivery for a non-reassuring fetal heart rate tracing was more common with misoprostol.

Umbilical arterial Doppler sonography for fetal surveillance in pregnancies complicated by pregestational diabetes mellitus

Antepartum fetal surveillance constitutes an essential component of the standards of care in managing pregnancies complicated by pregestational diabetes mellitus. Fetal hyperglycemia is associated with increased oxidative metabolism, hypoxemia and increased brain and renal perfusion without any significant changes in fetoplacental perfusion. Human cordocentesis data show that fetal hypoxemia and acidemia are associated with changes in the umbilical arterial Doppler indices in maternal diabetes mellitus complicated by fetal growth restriction or pre-eclampsia. Consistent with this, observational studies suggest significant diagnostic efficacy of the Doppler method in diabetic pregnancies complicated by vasculopathy, and in the presence of fetal growth restriction or hypertension. However, the relationship between abnormal umbilical arterial Doppler indices and the quality of glycemic control remains unproved. Although there are no randomized trials specifically addressing this issue, existing evidence suggests that Doppler velocimetry of the umbilical artery may be beneficial for antepartum fetal surveillance in diabetic pregnancies complicated by vasculopathy, fetal growth restriction or hypertension.

Nitration of N-methyl-D-aspartate receptor subunits following in vitro dephosphorylation of cerebral cortical membranes of newborn piglets

Previous studies have shown that activity of the cerebral N-methyl-D-aspartate (NMDA) receptor is modified by receptor nitration and phosphorylation. Since the sites for tyrosine phosphorylation and nitration are on adjacent carbon atoms, the present study tested the hypothesis that in vitro dephosphorylation of the NR1, NR2A and NR2B subunits of the NMDA receptor increases receptor nitration by peroxynitrite in cortical membranes of newborn piglets. To test this hypothesis, cerebral cortical P(2) membranes were prepared from normoxic and hypoxic newborn piglets and divided into dephosphorylated and non-dephosphorylated control groups. Dephosphorylation was performed in vitro by incubation with protein tyrosine phosphatase 1B and confirmed by immunoprecipitation with antiphosphotyrosine antibody. Dephosphorylated and non-dephosphorylated samples were nitrated with 0.5 mM peroxynitrite. Nitration was measured by immunoprecipitating with agarose-conjugated anti-nitrotyrosine antibody followed by Western blot analysis using specific anti -NR1, -NR2A and -NR2B primary antibodies. The data demonstrate that nitration of the NR1, NR2A and NR2B subunits of the NMDA receptor increases following dephosphorylation in both normoxic and hypoxic animals, however increase is much higher in hypoxic animals. We conclude that dephosphorylation at the site adjacent to the nitration site (ortho-position) on tyrosine residues of the NMDA receptor enhances nitration. Since in vitro nitration of the NMDA receptor increases the affinity of the glutamate recognition site and the receptor ion channel, we speculate that tyrosine dephosphorylation of the NMDA receptor will remove steric hindrance and facilitate nitration of tyrosine residues resulting in increased ion-channel activation in the hypoxic newborn brain.

Sepsis after Bartholin's duct abscess marsupialization in a gravida

BACKGROUND

Little information exists regarding sepsis following marsupialization of a Bartholin's duct abscess. We report a gravida who became septic after marsupialization.

CASE

A 30-year-old primigravida at 32 weeks' gestation underwent marsupialization of a Bartholin's gland abscess. Postoperatively, she developed fever with maternal and fetal tachycardia. She was admitted to the hospital and started on broad-spectrum antibiotics. Her temperature increased to 39 degrees C, and she became hypotensive. Blood work demonstrated evidence of disseminated intravascular coagulopathy. The patient was stabilized with aggressive fluid resuscitation, antibiotics, transfusion of blood products and oxygen therapy. Within 24 hours, the fever and coagulopathy resolved. She was discharged on postoperative day 5 and gave birth without complications at 38 weeks' gestation.

CONCLUSION

Pregnant women undergoing marsupialization of a Bartholin's gland abscess should be considered at high risk and managed accordingly.

Nicorandil decreases postischemic actin oxidation

This study examined the hypothesis that preconditioning can decrease postischemic oxidative protein damage. Isolated rat hearts were subjected to 25 min of normothermic global ischemia followed by 45 min of reperfusion. These were compared with hearts pretreated with 20 microM nicorandil or preconditioned with two cycles of ischemia. Changes in the high energy phosphates, ATP and phosphocreatine, were followed using (31)P-NMR spectroscopy. Protein carbonyls were assessed using an immunoblot technique. Postischemic hemodynamic function and high energy phosphates recovered to significantly (p <.05) higher levels in nicorandil-treated and ischemic preconditioned hearts as compared to controls. Postischemic protein carbonyl formation was highest in control reperfused hearts but reduced to intermediate between control and preischemic hearts by ischemic preconditioning and virtually prevented by nicorandil pretreatment, with a prominent band at 43 kDa significantly affected (p <.05). Based on immunoshift and immunoprecipitation studies, this band was identified as a mixture of actin isoforms. These studies support the conclusion that nicorandil diminishes protein oxidative damage in general, and specifically actin oxidation, which in the presence of improved supply of high energy phosphates, leads to enhanced postischemic contractile function.

Guidelines and recommendations for safe use of Doppler ultrasound in perinatal applications

Technological development has led to significant improvements in ultrasonographic capabilities in recent years, and this has been accompanied by increases in acoustic output. Meanwhile, there is a developing trend to use ultrasound at early stages of pregnancy when the developing embryo is known to be highly sensitive to damage by physical agents. The advent of pulsed spectral Doppler and color flow imaging has revolutionized perinatal applications. Doppler ultrasound has become widely accepted as a valuable diagnostic tool in obstetric medicine, where it has particular benefits for high-risk pregnancies. The benefits of Doppler screening are less well established. United States Food and Drug Administration (FDA) regulations now provide an option whereby equipment that provides a form of output display can be used to apply substantially higher acoustic output to the embryo or fetus than equipment approved for use under application-specific intensity limits. The Output Display Standard recently adopted by the FDA, in the USA, encourages self-regulation of acoustic exposure by the ultrasound user, on the basis of assumed knowledge of the implications of biophysical interactions. When modern sophisticated equipment is used at maximum operating settings for Doppler examinations, the acoustic outputs are sufficient to produce obvious biological effects, e.g. significant temperature increase in tissue or visible motion of particles due to radiation pressure streaming effects. The risk of inducing thermal effects is greater in the second and third trimesters, when fetal bone is intercepted by the ultrasound beam and significant temperature increase can occur in the fetal brain. Non-thermal bioeffects may be more significant in early gestation, when the relatively loosely tethered embryonic tissues are exposed to an ultrasound beam in a liquid path. The likelihood of producing cavitation-type non-thermal effects is enhanced by the presence in the sound-field of gas-encapsulated echo-contrast media. To ensure the continued safe use of ultrasound in obstetrics, it is important that international ultrasound organizations, such as the International Perinatal Doppler Society, issue advice to members to allow sensible assessment of risk: benefit and the practical implementation of the ALARA (as low as reasonably achievable) principle.

Post-hypoxic magnesium decreases nuclear oxidative damage in the fetal guinea pig brain

This study was to determine if administration of MgSO(4) after the hypoxic insult (post-hypoxia) would attenuate neuronal damage in the fetal guinea pig brain. Pregnant guinea pigs (45-60 days gestation) were exposed to hypoxia (7% O2) for 1 h. Following hypoxia, one group recovered for 24 h with no additional treatment (post-hypoxia) and another group received MgSO(4), 300 mg/kg i.p., followed by 100 mg/kg i.p., each hour for three doses (post-hypoxia+Mg) and allowed to recover for 24 h. Fetal brain magnesium content was decreased (P<0.05) 4 h post-hypoxia which was prevented by treatment with MgSO(4). High energy phosphates were significantly lower (P<0.05) in the post-hypoxia group which was partially prevented by post-hypoxic magnesium. Na+,K+-ATPase activity was significantly lower (P<0.05) and nuclear membrane fluorescent compounds were significantly higher (P<0.05) in the post-hypoxia group but were not significantly changed in the post-hypoxia+Mg group compared with the normoxic control group. DNA fragmentation was observed to be lower in the Mg-treated post-hypoxic group. This study demonstrates that maternal MgSO(4) administration following in utero hypoxia prevents associated decreases in fetal brain magnesium and suppresses alterations in both the neuronal and nuclear membranes and genomic fragmentation in the fetal guinea pig brain.

Postpartum angiographic embolization for vulvovaginal hematoma. A report of two cases

BACKGROUND

Puerperal hematomas can become a life-threatening obstetric emergency. Their incidence is 1 or 2/1,000 deliveries. When mainstay methods of suture and packing fail, arterial embolization becomes an excellent alternative to definitive treatment, laparotomy.

CASES

A 32-year-old woman, para 2-0-2-2, developed extreme rectal and vulvar pain one hour postpartum. A 12 x 10-cm vulvovaginal hematoma was identified, drained, sutured and packed. Bleeding continued, blood products were administered, and selective angiographic embolization of the pudendal and inferior gluteal arteries was successfully performed. A 31-year-old woman, para 1-0-1-1, developed a left vaginal hematoma immediately postpartum. She failed vaginal packing and underwent angiographic arterial embolization successfully. The patient was discharged on the fourth postpartum day. At six weeks postpartum, neither patient had evidence of hematoma formation.

CONCLUSION

In the setting of a puerperal hematoma refractory to conventional first-line therapy, arterial embolization provides a rational, effective alternative for achieving hemostasis with minimal morbidity.

Brain perfusion monitoring with frequency-domain and continuous-wave near-infrared spectroscopy: a cross-correlation study in newborn piglets

The newborn piglet brain model was used to correlate continuous-wave (CW) and frequency-domain (FD) near-infrared spectroscopy. Six ventilated and instrumented newborn piglets were subjected to a series of manipulations in blood oxygenation with the effects on brain perfusion known to be associated with brain hypoxia-ischaemia. An excellent agreement between the CW and FD was demonstrated. This agreement improved when the scattering properties (determined by the FD device) were employed to calculate the differential pathlength factor, an important step in CW data processing.

Obstetric conditions and erythropoietin levels

OBJECTIVE

Our purpose was to evaluate and compare erythropoietin levels as related to obstetric conditions, including acute and chronic bleeding, preeclampsia, and multiple gestations.

STUDY DESIGN

During April 1999 all women in the labor and delivery unit with delivery expected to occur within 24 to 72 hours of admission had erythropoietin and hematocrit values obtained. First-trimester hematocrit values, obstetric problems, medications, and history of vaginal bleeding were obtained from patient interview, examination, and the prenatal record. Statistics were analyzed by the Student t test and chi(2).

RESULTS

During a 1-month period, 302 consecutive women were divided into 5 groups on the basis of obstetric events. Group 1 consisted of women with normal, uncomplicated term singleton gestations (n = 230); group 2, women with acute vaginal bleeding (n = 10); group 3, women with chronic vaginal bleeding (n = 29); group 4, women with multiple gestations (n = 13); and group 5, women with preeclampsia (n = 16). The mean erythropoietin level in group 1 (20. 2 +/- 10.3 mU/mL) was significantly different from values in the other 4 groups (group 2, 74.2 +/- 29.2 mU/mL; group 3, 65.0 +/- 33.0 mU/mL; group 4, 34.8 +/- 16.8 mU/mL; group 5, 43.4 +/- 11.4 mU/mL; P <.001). The admission hematocrit for group 1 (0.369 +/- 0.029) was significantly greater than for groups 2 and 3 (group 2, 0.323 +/- 0. 024; group 3, 0.321 +/- 0.023; P <.001) and significantly lower than for group 5 (0.384 +/- 0.022; P <.05).

CONCLUSION

The maternal serum erythropoietin level varies depending on the events occurring during gestation. Acute and chronic bleeding, multiple gestations, and preeclampsia are all associated with various serum erythropoietin levels.

Role of frequency domain optical spectroscopy in the detection of neonatal brain hemorrhage--a newborn piglet study

OBJECTIVE

Inability of continuous wave (CW) optical spectroscopy to measure changes in scattering, and the use of an arbitrary rather than an actual baseline, makes the CW method highly susceptible to errors that can lead to a false-positive or false-negative diagnosis. Our objective was to assess whether, and to what extent, the use of quantitative frequency domain spectroscopy would improve our ability to detect and monitor the development of brain hemorrhage.

METHODS

A dual-channel frequency-domain tissue spectrometer (Model 96208, ISS, Inc., Champaign, IL) was used to monitor the development of experimental subcortical and periventricular-intraventricular hemorrhage (IVH) in 10 newborn piglets (blood injection model). The multidistance approach was employed to calculate the absorption and reduced scattering coefficients and hemoglobin changes from the ac, dc, and phase values acquired at four different source-detector distances and at 752 nm and 830 nm.

RESULTS

There were significant absorption and scattering changes in the subcortical hematoma (n = 5) and the IVH groups (n = 5). The smallest detectable amount of blood in the brain was 0.04 ml. Changes associated with subcortical hematoma were several times higher than those associated with IVH, and correlated better with the estimated cross-sectional area of the hematoma than with the volume of the injected blood. As opposed to IVH, there was a significant absorption difference between the injured (subcortical hematoma) and normal side of the brain, probably because in case of IVH a significant volume of the injected blood had accumulated/spread beyond the reach of the probe.

CONCLUSION

Clearly, frequency-domain spectroscopy cannot increase our ability to quantify the volume (size) or the oxygenation of the injected blood, especially in the case of IVH. However, the ability to quantify the baseline tissue absorption and scattering would significantly improve diagnostic performance, and may allow for early identification and treatment of neonatal brain hemorrhage.

Association of increased ubiquitinated proteins with cardiac apoptosis

Intracellular proteases play an important role in the regulation of apoptosis. A study was performed to determine whether inhibition of the cardiac ATP-dependent ubiquitin 26S protease complex affects cardiomyocyte apoptosis. Isolated rat hearts were perfused for up to 80 min with Krebs-Henseleit buffer +/- the 26S-proteasome inhibitor, MG132 (Z-leu-leu-leucinal). TUNEL-staining of hearts perfused with 25 microM MG132 for 50 min revealed a significant increase (p < 0.05) in the apoptotic index from 1.1% to 15.5% when compared with control hearts perfused with buffer only. Histology of adjacent myocardial sections revealed no signs of necrotic or late apoptotic (nuclear condensation) changes, indicating that the TUNEL-positive nuclei were in the early stages of apoptosis. This early stage of apoptosis was associated with a significant (p < 0.05) reduction in cardiac function. There was a 63% decrease in the rate pressure product in hearts perfused with 25 microM MG132 as compared with a 35% decrease in control hearts over the 80-min perfusion period. Soluble ubiquitin-conjugated proteins, as detected by probing with a specific antibody to ubiquitin, were increased in MG132-treated hearts. In hearts perfused with 50 microM MG132, a greater accumulation of ubiquinated proteins was observed accompanied by a more rapid and greater reduction in hemodynamic function. These observations indicate that prolonged inhibition of the ubiquitin-26S-proteasome results in cardiomyocyte apoptosis accompanied by increased ubiquinated proteins, thus suggesting that accumulation of these abnormal proteins may act as a signal to activate the cell death program.

Real-time optical imaging of experimental brain ischemia and hemorrhage in neonatal piglets

Our objective was to study the development of experimental brain ischemia and hemorrhage by real-time optical imaging. Optical imaging is based on the ability of near infrared light to non-invasively penetrate through the intact scalp and skull and measure brain concentrations of oxy- and deoxyhemoglobin, dominant brain absorbers. Optical imaging was performed in 7 anesthetized, instrumented, and ventilated newborn piglets subjected to the injection of 0.3 cc of saline followed by 2 cc of blood into the left frontal subcortical brain region via a needle inserted through the skull with stereotactic guidance. The image-acquisition rate of 5.26 images per sec allowed for real-time imaging. The detection threshold of the imager at the estimated depth of 1-1.5 cm was approximately 70 microL for saline and approximately 40 microL for blood. The imager readily detected five subcortical hematomas and two large bilateral subarachnoid hemorrhages. The imager detected a global decrease in brain absorption associated with the volume-injection-related increase in intracranial pressure in the surrounding ipsilateral and contralateral brain. Any decrease in brain absorption is an equivalent to brain ischemia. This study demonstrates the capability of optical imaging in detecting brain ischemia and hemorrhage in real-time with high temporal and spatial resolution.

Non-invasive optical monitoring of the newborn piglet brain using continuous-wave and frequency-domain spectroscopy

We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 microM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured in the brain after the piglet had been sacrificed.

Non-invasive optical mapping of the piglet brain in real time

We have performed non-invasive, real-time optical mapping of the piglet brain during a subcortical injection of autologous blood. The time resolution of the optical maps is 192 ms, thus allowing us to generate a real-time video of the growing subcortical hematoma. The increased absorption at the site of blood injection is accompanied by a decreased absorption at the contralateral brain side. This contralateral decrease in the optical absorption and the corresponding time traces of the cerebral hemoglobin parameters are consistent with a reduced cerebral blood flow caused by the increased intracranial pressure.

Oxygen free radical generation during in-utero hypoxia in the fetal guinea pig brain: the effects of maturity and of magnesium sulfate administration

Previous studies have shown, employing direct measurements with electron spin resonance (ESR) spectroscopy, that hypoxia induces an increased production of oxygen free radicals (OFR) in the brain of the guinea pig fetus. The present study using the same approach, investigated the effects of maturity and Mg2+-pretreatment on hypoxia-induced OFR formation in the guinea pig fetal brain. The normoxic and the hypoxic groups were exposed for 60 min to 21% or 7% oxygen, respectively. The control group consisted of term fetuses exposed to normoxia (n=7) and hypoxia (n=7). The experimental groups consisted of the following: (a) for the investigation on maturity effect, preterm fetuses (40 days) exposed to normoxia (n=6) or hypoxia (n=6); and (b) for the Mg2+-pretreatment investigation, term fetuses (60 days) exposed to normoxia (n=6) or hypoxia (n=6) following maternal pretreatment with Mg2+ which consisted of an initial bolus of MgSO4 (600 mg/kg, i.p.) 1 h prior to hypoxia followed by a second dose (300 mg/kg, i.p.). Oxygen free radicals were measured by ESR spectroscopy in the fetal cerebral cortical tissue utilizing phenyl-N-tert-butylnitrone (PBN) spin trapping. Fetal brain tissue hypoxia was documented biochemically by decreased tissue levels of ATP and phosphocreatine. In the control group of term fetuses, the cortical tissue from hypoxic fetuses showed a significant increase in spin adducts (71% increase, p<0.01). In the preterm group, the cortical tissue from hypoxic fetuses showed a 33% increase in spin adducts (p<0.001). The baseline free radical generation during normoxia was 22.5% higher at preterm than at term (41.4+/-3.5 units/g issue vs. 33.8+/-9.3 units/g tissue, p<0.05). In Mg2+-treated groups, spin adduct levels in cortical tissue from hypoxic fetuses did not significantly differ from those of the normoxic group (30.2+/-9.9 units/g tissue, normoxic-Mg2+ vs. 30. 6+/-8.1 units/g tissue, hypoxic-Mg2+). The results indicate that the fetal brain at term may be more susceptible to hypoxia-induced free radical damage than at preterm and that Mg2+ administration significantly decreased the hypoxia-induced increase in oxygen free radical generation in the term fetal guinea pig brain in comparison with non-treated hypoxic group.

Direct measurement of oxygen free radicals during in utero hypoxia in the fetal guinea pig brain

The present study tested the hypothesis that maternal hypoxia induces oxygen free radical generation in the fetal guinea pig brain utilizing techniques of electron spin resonance spectroscopy and alpha-phenyl-tert-butyl nitrone (PBN) spin trapping. Pregnant guinea pigs of 60 days gestation were divided into normoxic and hypoxic groups and exposed to 21% or 7% oxygen for 60 min. Free radical generation was documented by measuring the signal of PBN spin adducts. Fluorescent compounds were determined as an index of lipid peroxidation and the activity of Na+,K+-ATPase was determined as an index of brain cell membrane function. Hypoxic fetal cerebral cortical tissue showed a significant increase in spin adducts (normoxic: 33.8+/-9.3 units/g tissue vs. hypoxic: 57.9+/-9.2 units/g tissue, p<0.01) and fluorescent compounds (normoxic: 0.639+/-0.054 microg quinine sulfate/g brain vs. 0.810+/-0.102 microg quinine sulfate/g brain, p<0.01) and a decrease in Na+,K+-ATPase activity (normoxic: 43.04+/-2.50 micromol Pi/mg protein/h vs. hypoxic: 33. 80+/-3.51 micromol Pi/mg protein/h, p<0.001). These results demonstrate an increased free radical generation during hypoxia in the fetal guinea pig brain. The spectral characteristics of the radicals were consistent with those of alkoxyl radicals. The increased level of fluorescent compounds and decreased activity of Na+,K+-ATPase indicated hypoxia induced brain cell membrane lipid peroxidation and dysfunction, respectively. These results directly demonstrate an increased oxygen free radical generation during hypoxia and suggest that hypoxia-induced increase in lipid peroxidation and decrease in membrane function, as indicated by a decrease in Na+,K+-ATPase activity, are consequences of increased free radicals. The nature of predominantly present alkoxyl radical indicates ongoing lipid peroxidation during hypoxia. The direct demonstration of oxygen free radical generation during hypoxia is the critical missing link in the mechanism of hypoxia-induced brain cell membrane dysfunction and damage.

Simple cyst in the postmenopausal patient: detection and management

The aims of our study were to determine the prevalence of simple ovarian cysts in asymptomatic postmenopausal patients and to investigate the natural history of these cysts by ultrasonographic follow-up examinations. Three thousand five hundred and eighty-five women participated in the volunteer pelvic cancer screening program. Entry criteria were as follows: postmenopausal, no clinical symptoms, and no previous gynecologic pathology. An anechoic, small cyst less than 5 cm in greatest diameter was classified as a simple ovarian cyst. A scoring system to determine malignant potential had been established previously. All simple cysts had a score of 2 or less and had a morphology typical of benign lesions. In the case of a positive finding, the patient would be seen at 3 to 6 month intervals. The decision for surgical intervention was made by a private gynecologist or patient or if an interval change was noted. One thousand seven hundred and sixty-nine postmenopausal women (49.34% of all patients from the screening program) participated in this study. One hundred and sixteen simple cysts were found, with a prevalence of 6.6% in our population. Among those patients, 27 (23.28%) simple cysts resolved spontaneously, 69 (59.48%) have persisted, and 20 (17.24%) have been lost to follow-up study. Eighteen women (26.09%) with persistent simple ovarian cyst underwent surgery. No malignant ovarian conditions were identified. In conclusion, simple ovarian cysts are more common in postmenopausal women than previously was thought. This condition is very unlikely to be malignant and can be followed conservatively.

Heterotopic triplet pregnancy. Report of a case with successful twin intrauterine gestation

BACKGROUND

Reports of coexisting multiple intrauterine pregnancies and ectopic pregnancy are extremely rare. We present one case with early sonographic diagnosis of heterotopic pregnancy, successful laparoscopic treatment and a subsequent normal pregnancy course and outcome of the intrauterine twin gestation.

CASE

A 29-year-old woman, gravida 1, para 0, presented for her first prenatal visit at 5 weeks of gestation with pelvic pain. She had conceived with 75 IU leutinizing hormone and follicle-stimulating hormone and homologous intrauterine insemination. The sonogram confirmed a dichorionic twin intrauterine pregnancy and left tubal pregnancy at 7 weeks of gestation. The patient underwent a laparoscopic left salpingostomy and removal of the ectopic pregnancy. Level II sonogram showed a grossly unremarkable twin gestation at 20 weeks. Labor was induced at 37 weeks of gestation due to mild preeclampsia and underwent vaginal delivery without difficulties. The first twin was a girl, weighing 2,722 g, with Apgar scores of 9/9. The second twin, a boy, was delivered 10 minutes later, weighing 2,863 g, with Apgar scores of 9/9.

CONCLUSION

Early sonography is essential for the diagnosis of heterotopic pregnancy, and timely surgical intervention can save the intrauterine twin gestation, with a subsequent normal pregnancy course and outcome.

Effect of long-term cocaine administration to pregnant ewes on fetal hemodynamics, oxygenation, and growth

OBJECTIVE

To assess uterine and fetal blood flows by Doppler velocimetry and fetal growth and oxygenation in pregnant ewes treated daily with cocaine and to determine whether cocaine impairs fetal cardiac and cerebral reactivity.

METHODS

The study groups received 70 mg (n = 7) or 140 mg (n = 7) of cocaine and the control group (n = 7) received placebo injected intramuscularly daily on days 60-134. Hemodynamic data were measured at rest and during two acute hypoxic tests at cesarean delivery performed on day 134.

RESULTS

The fetal heart rate (FHR) and umbilical and uterine resistance indices (RIs) were higher in the cocaine groups than in the control group (FHR: 187 +/- 8 and 166 +/- 8 beats per minute at 83 and 123 days, respectively, in controls and 9-11% higher in cocaine groups; umbilical RI: 0.79 +/- 0.06, 0.60 +/- 0.04, and 0.52 +/- 0.06, at 83, 105, and 123 days, respectively, in controls and 11-17% higher in the cocaine groups [P < .01]; and uterine RI: 0.40 +/- 0.05, 0.40 +/- 0.04, and 0.37 +/- 0.04, at 83, 105, and 123 days, respectively, in controls and 13-35% higher in cocaine groups [P < .05]). At delivery on day 134, the following characteristics were found to be different in the cocaine groups: fetal weight (4.03 +/- 0.2 kg in controls and 15-21% lower in the cocaine groups [P < .02]), partial pressure of oxygen (26.5 +/- 1.4 mmHg in controls and 15-16% lower in cocaine groups [P < .05]), umbilical RI (0.40 +/- 0.03 in controls and 11-17% higher in cocaine groups [P < .01]), cerebral RI (0.61 +/- 0.03 in controls and 9-15% lower in cocaine groups [P < .01]), and cerebral-umbilical ratio (1.52 +/- 0.04 in controls and 22-23% lower in cocaine groups [P < .001]). During the hypoxic tests, the cerebral RI (P < .05) and the cerebral-umbilical ratio (P < .05) decreased significantly less in the two cocaine groups. The FHR response was reduced significantly in the two cocaine groups (P < .05).

CONCLUSION

Long-term exposure to cocaine induces uterine and fetal blood flow disorders, fetal growth restriction, and hypoxia. It reduces the capability of the cerebral vessels to vasodilate and the heart rate to increase during acute hypoxia.

Fetal heart rate patterns in pregnancies complicated by maternal diabetes

OBJECTIVE

To compare the fetal heart rate (FHR) pattern between fetuses of well controlled diabetic and non diabetic mothers using a computerized analysis of FHR.

STUDY DESIGN

Weekly fetal surveillance was performed in 99 fetuses of mothers with diabetes class A, 21 fetuses of mothers with diabetes class B-R, and 55 fetuses of non-diabetic women, starting at 30 weeks' gestation. All diabetic patients were well controlled. Fetal surveillance included a computerized analysis of the FHR, umbilical and uterine Doppler velocimetry, and a biophysical profile. Changes of FHR variation, frequency of FHR accelerations, and umbilical and uterine Doppler velocimetry were calculated using a regression analysis for each patient. The average slopes and the intercept at 30, 34, and 38 weeks' gestation of these variables were compared among the three groups.

RESULTS

The slope of FHR variation and the frequency of accelerations had a lower rate of increase during the third trimester in fetuses of mothers with diabetes class A (0.84 +/- 0.25 ms/week and 0.06 +/- 0.02/20 min/week, respectively) compared with fetuses of non-diabetic mothers (1.34 +/- 0.55 ms/week and 0.5 +/- 0.1/20 min/week, respectively). In fetuses of mothers with diabetes class B-R, FHR variation did not change with gestation (-0.011 +/- 0.2 ms/week) with a small increase in the frequency of accelerations (0.02 +/- 0.004/20 min/week). While no differences were observed at 30 weeks' gestation, FHR variation and the frequency of accelerations were significantly reduced at 34 weeks' gestation in fetuses of mothers with diabetes class B-R compared with fetuses of non-diabetic mothers (P < 0.01). At 38 weeks' gestation, fetuses of mothers with diabetes class B-R and diabetes class A had both significantly reduced FHR variation as well as frequency of accelerations compared with fetuses of non-diabetic mothers (P < 0.01). The rate of decrease of the umbilical and uterine artery S/D ratios were similar among the three groups.

CONCLUSIONS

The FHR pattern appears to be different in fetuses of well controlled diabetic mothers when related to fetuses of non-diabetic mothers. Disease specific standards should be considered for interpretation of FHR patterns in diabetic pregnancies.

Computerized analysis of fetal heart rate changes after antepartum external cephalic version

OBJECTIVE

To assess the fetal heart rate (FHR) changes following external cephalic version using a computerized FHR monitor.

STUDY DESIGN

We performed 116 external cephalic versions on 106 pregnant women at 36-40 weeks' gestation. Tocolysis (magnesium sulfate) was given to 39 patients (34%). Computerized FHR monitoring was performed for 20-30 minutes before and for 20-30 minutes after the procedure. In addition, we analyzed the results of the FHR tracing obtained during the first 10 minutes following the procedure.

RESULTS

External cephalic version was successful in 40% of the patients. In the group of patients who were not treated with magnesium sulfate, FHR variation and the number of accelerations per 10 minutes were significantly reduced during the first 10 minutes following the procedure as compared with those factors on the FHR tracings obtained before or 20-30 minutes following the procedure (P < .05). In the group of patients who were treated with magnesium sulfate, FHR variation and the number of accelerations per 10 minutes were significantly reduced before and 10 minutes after the procedure as compared with the FHR tracings obtained 20-30 minutes following the procedure (P < .05). In both groups the basal FHR was significantly lower during the first 20-30 minutes following the procedure (P < .05). FHR decelerations were observed following the procedure in only two patients. None of the 106 fetuses had a low Apgar score or were admitted to the neonatal intensive care unit.

CONCLUSION

External cephalic version appears to be safe for the mother and fetus, although transient FHR changes may occur following the procedure.

Human chorionic gonadotropin stimulates placental prorenin secretion: evidence for autocrine/paracrine regulation

Functional regulation of the placental renin-angiotensin system remains incompletely defined. Evidence indicates that synthesis and secretion of prorenin in the placenta and gestational sac decrease with advancing gestational age. Possible explanations for this developmental effect include the regulatory influences by locally released hormones, such as CG. To address this question, the effect of CG on prorenin secretion was evaluated in a human placental explant model. In this study, prorenin concentrations were measured in the media and tissue of cultured explants from term placentas. In addition, the role of cAMP in mediating hormone-regulated prorenin secretion was evaluated. Media and tissue concentrations of prorenin increased (2- and 3-fold, respectively) in a concentration-dependent fashion after 48 h of incubation with CG (0.03-300 IU/ml). Selective inhibition of phosphodiesterases by Ro 20-1724 (type IV) and cilostamide (type III) resulted in a marked potentiation of CG-induced prorenin secretion. Media concentrations of cAMP were also elevated with CG treatment and correlated with prorenin values. Prorenin secretion induced by CG was markedly attenuated by the cAMP-dependent protein kinase inhibitor, H-89. These results indicate that placental prorenin secretion may be locally regulated by CG and mediated by cAMP signal transduction mechanisms.

In vitro and in vivo validation of time domain velocity and flow measurement technique

This study was undertaken to validate the time domain processing method for measuring (1) the peak velocity in comparison to pulsed-wave spectral Doppler findings in an in vitro system; (2) the volumetric flow in comparison to the actual flow measured by a graduated cylinder in an in vitro circulation; and (3) the volumetric flow in comparison to a transit time flowmeter in a permanently instrumented neonatal lamb model. A prototype implementation of time domain processing in a commercial ultrasound device was used. For velocimetry, both time domain processing and Doppler methods showed low variance, low intrarater variability (0.03 and 0.09%, respectively), high reliability coefficients (97% and 96%, respectively), and a significant correlation (r = 0.96; P < 0.001). For in vitro flow quantification, time domain processing and graduated cylinder methods showed low variance, low intrarater variability (0.09 and 0.01%, respectively), high reliability coefficients (99.60% and 99.96%, respectively), and a significant correlation (r = 0.98, P < 0.001). For in vivo flow quantification, time domain processing and transit time flowmeter showed a significant correlation (r = 0.96; P < 0.001). Within the limits of the in vitro and in vivo experimental conditions, this study proves the validity of the time domain processing sonographic technique for measuring peak flow velocity and volumetric flow.