Emanuela Marinoni

Adrenomedullin, a New Vasoactive Peptide, Is Increased in Preeclampsia

Adrenomedullin is a novel peptide that elicits a long-lasting vasorelaxant activity. Recently, we found high concentrations of adrenomedullin in maternal and umbilical cord plasma and in amniotic fluid in full-term human pregnancy, indicating a role of this peptide during gestation. To investigate the possibility that adrenomedullin is involved in the pathophysiology of preeclampsia, we measured its concentration in maternal and fetoplacental compartments. We studied 12 normotensive nonpregnant women, 13 hypertensive nonpregnant subjects, 29 patients with preeclampsia, and 30 normotensive pregnant women. In all patients, plasma was collected from the cubital vein, and amniotic fluid samples were obtained by transabdominal amniocentesis or at elective cesarean section. Plasma samples from umbilical vein and placental tissues were collected at delivery. Adrenomedullin was assayed on plasma and amniotic fluid samples using a specific radioimmunoassay, and its localization and distribution on placental sections was determined by immunohistochemistry. Adrenomedullin concentrations were higher in hypertensive than in normotensive nonpregnant patients. Pregnant women had higher adrenomedullin levels than nonpregnant subjects, although maternal plasma adrenomedullin concentrations did not differ between normal pregnant and preeclamptic women. Preeclamptic patients showed higher concentrations (P<0.01) than normotensive pregnant women of adrenomedullin in amniotic fluid (252+/-29 versus 112+/-10 fmol/ micromol creatinine) and umbilical vein plasma (18.1+/-2.1 versus 8. 5+/-1.1 fmol/mL). Increased local production of adrenomedullin is associated with preeclampsia. The fetus seems to be responsible for the higher levels of this hormone. Increased adrenomedullin concentrations may be necessary to maintain placental vascular resistance and/or fetal circulation at a physiological level.

Immunoreactive adrenomedullin in human fetoplacental tissues

OBJECTIVE Adrenomedullin is increased in maternal plasma in pregnancy and has been found in very high concentrations in amniotic fluid and umbilical plasma. To identify adrenomedullin-producing tissue in pregnancy we measured adrenomedullin concentration and distribution in fetoplacental tissues. STUDY DESIGN By use of a specific radioimmunoassay we determined the concentrations of adrenomedullin and, by immunohistochemical studies, its localization and distribution in fetal membranes and placentas collected at elective cesarean section from 11 healthy pregnant women at term. RESULTS The content of adrenomedullin in placentas (117.7 +/- 7.8 pg/mg wet tissue) and fetal membranes (168.7 +/- 2.3 pg/mg wet tissue) was similar to the adrenomedullin concentration in adrenal medulla (157.3 +/- 4.4 pg/mg wet tissue). Adrenomedullin staining appears to be greater in fetal membranes than in placentas and was localized in amnion and trophoblast cells. In term placentas positive staining was detected predominantly in extravillous trophoblast cells, although a few syncytiotrophoblast cells and endothelial cells of primary villi stained for adrenomedullin. CONCLUSION This study provides evidence that is consistent with fetoplacental tissues as a site of synthesis or action of adrenomedullin during pregnancy.

Circulating S100β protein is increased in intrauterine growth-retarded fetuses

To determine whether S100β, an acidic calcium-binding protein previously demonstrated as a reliable indicator of a brain lesion, could be helpful in the detection of brain distress in intrauterine growth-retarded (IUGR) fetuses, we studied, by a case-control study, the correlation between S100B protein and the degree of fetoplacental blood flow impairment. Maternal and umbilical blood samples and placental tissue specimens were collected at delivery from IUGR pregnancies with normal (n = 10) or abnormal (n = 10) umbilical artery Doppler findings and from 40 uncomplicated pregnancies. S100β protein levels were measured by means of a specific RIA, and flow velocimetry waveforms were recorded from uterine, umbilical, and fetal middle cerebral arteries. Overall mean S100β proteins in umbilical plasma levels were higher (p < 0.05) in IUGR patients (121.8 ± 70.4 fmol/mL) than in control patients (54.7 ± 21.9 fmol/mL). IUGR fetuses with redistribution of blood flow showed the higher concentration of the protein (163.7 ± 55.2 fmol/mL). Fetal S100β concentrations correlated with middle cerebral artery pulsatility index (r = −0.536, p < 0.03) and with umbilical artery pulsatility index to middle cerebral artery pulsatility index ratio (r = 0.469, p < 0.03). No difference in the localization or intensity of S100β staining in the placental tissues or cord between uncomplicated and IUGR pregnancies was found. This study provides evidence that circulating S100β protein is increased in IUGR fetuses and correlates with cerebral hemodynamics, suggesting that it may represent an index of cerebral cell damage in the perinatal period.

Urinary S100B protein measurements: A tool for the early identification of hypoxic-ischemic encephalopathy in asphyxiated full-term infants.

ObjectiveHypoxic-ischemic encephalopathy (HIE) is one of the major causes of perinatal mortality and morbidity. To date, there are no reliable methods to detect which infants will develop brain damage after asphyxia insult. Design and SettingProspective study conducted in three tertiary departments of neonatology from December 1999 to July 2002. ParticipantsA total of 44 infants with perinatal asphyxia and 68 control infants. InterventionRoutine laboratory variables, neurologic patterns, ultrasound imaging, and urine concentrations of S100B protein were determined at nine time points. Main Outcome MeasuresThe concentrations of S100B protein in urine were measured using an immunoluminometric assay at first urination and 4, 8, 12, 16, 20, 24, 48, and 72 hrs after birth. The results were correlated with the presence or absence of hypoxic-ischemic encephalopathy. Routine laboratory parameters and neurologic patterns were assessed at the same time as urine sampling. ResultsS100B protein levels were significantly higher in samples collected at all monitoring time points from newborns with perinatal asphyxia with or without hypoxic-ischemic encephalopathy than in samples from normal infants (all p < .001). When asphyxiated infants were subdivided according to the presence of mild or absence of hypoxic-ischemic encephalopathy (group A) and of moderate or severe hypoxic-ischemic encephalopathy (group B), S100B levels were significantly higher at all the predetermined monitoring time points in group B infants than group A or control infants (all p < .001). An S100B concentration cutoff of 0.41 &mgr;g/L at first urination had a sensitivity of 91.3% and a specificity of 94.6% for predicting the development of hypoxic-ischemic encephalopathy. The sensitivity and specificity of measurements obtained from 4 to 72 hrs after birth were up to 100% and 98.8%, respectively. ConclusionsLongitudinal S100B protein measurements in urine soon after birth are a useful tool to identify which asphyxiated infants are at risk of hypoxic-ischemic encephalopathy and its possible neurologic sequelae.

S100B protein is increased in asphyxiated term infants developing intraventricular hemorrhage.

ObjectiveTo establish whether S100B protein may be useful in the early detection of intraventricular hemorrhage in asphyxiated term infants. DesignCase-control study. PatientsTwenty full-term newborns with intraventricular hemorrhage, 20 asphyxiated infants without intraventricular hemorrhage, and 80 normal newborns. InterventionsRoutine laboratory variables and neurologic patterns were assessed at birth after 12 and 72 hrs. Ultrasound imaging and middle cerebral artery Doppler velocimetry pulsatility index were recorded at 12 and 72 hrs after birth. S100B protein blood concentrations were determined at 12 hrs. Measurements and Main ResultsS100B protein levels were significantly higher in samples collected from newborns who developed intraventricular hemorrhage (1.87 ± 0.60 &mgr;g/L) than from those who did not develop intraventricular hemorrhage (0.72 ± 0.39 &mgr;g/L) or from normal infants (0.66 ± 0.31 &mgr;g/L). Multiple logistic regression analysis showed a significant correlation between circulating S100B protein concentrations and the occurrence of intraventricular hemorrhage. ConclusionsThis study suggests that elevated S100B protein represents a useful tool for the early detection of intraventricular hemorrhage in the postasphyxia period when clinical examination and cerebral ultrasound might still be silent.

New markers of neonatal neurology

Hypoxia–ischemia (H–I) constitutes the main phenomenon responsible for brain–blood barrier permeability modifications leading to cerebral vascular auto-regulation loss in newborns. Hypotension, cerebral ischemia, and reperfusion are the main events involved in vascular auto-regulation loss leading to cell death and tissue damage. Reperfusion could be critical since organ damage, particularly of the brain, may be amplified during this period. An exaggerated activation of vasoactive agents, of calcium mediated effects could be responsible for reperfusion injury (R-I), which, in turns, leads to cerebral hemorrhage and damage. These phenomena represent a common repertoire in newborns complicated by perinatal acute or chronic hypoxia treated by risky procedures such as mechanical ventilation, nitric oxide supplementation, brain cooling, and extracorporeal membrane oxygenation (ECMO). Despite accurate monitoring, the post-insult period is crucial, as clinical symptoms and standard monitoring parameters may be silent at a time when brain damage is already occurring and the therapeutic window for pharmacological intervention is limited. Therefore, the measurement of circulating biochemical markers of brain damage, such as vasoactive agents and nervous tissue peptides is eagerly awaited in clinical practice to detect high risk newborns. The present review is aimed at investigating the role of biochemical markers such as adrenomedullin, a vasoactive peptide; S100B, a calcium binding protein, activin A, a glycoprotein, in the cascade of events leading to I-R injury in newborns complicated by perinatal asphyxia.

Amniotic fluid nitric oxide and uteroplacental blood flow in pregnancy complicated by intrauterine growth retardation

Objective To examine the correlation between placental nitric oxide production and uteroplacental blood flow.

Nitric oxide in preeclampsia: lack of evidence for decreased production

The purpose of our study was to determine the involvement of the L-arginine-NO system in preeclampsia. We studied 26 patients with preeclampsia and 27 normotensive pregnancies. Maternal and cord plasma, urine and amniotic fluid were assayed for nitric oxide metabolites (nitrite and nitrate) using the Griess reaction. Sections of placenta and fetal membranes were immunostained with polyclonal anti-endothelial and anti-neuronal nitric oxide synthase antibodies. The concentration of nitrate in the amniotic fluid of preeclamptic patients (median 10.3 mumol/mg creatinine) was significantly higher (P < 0.001) than in the normotensive group (5.6 mumol/mg creatinine). Nitrate concentrations in maternal and cord plasma and in urine were similar in the two groups. Endothelial cells of the villi of preeclamptic placentas showed a higher positivity in endothelial nitric oxide synthase immunostaining with respect to normotensive controls. Our results indicate that feto-placental NO production is not reduced in preeclampsia. In contrast, the increased concentrations of NO metabolites in amniotic fluid and the positive immunostaining of endothelial nitric oxide synthase in the placental villi suggest that the placental L-arginine-NO system is up-regulated in preeclampsia.

Ontogenetic localization and distribution of S-100β protein in human placental tissues

OBJECTIVE To investigate whether S‐100β, a brain‐specific protein found in amniotic fluid and fetal circulation, is present in fetoplacental tissues throughout gestation. METHODS S‐100β protein localization and concentration were assessed in placentae, fetal membranes, and cord vessels. Tissues were obtained from 40 pregnant women at different gestational ages: first trimester (n = 10), second trimester (n = 10), early third trimester (n = 10), and late third trimester (n = 10). RESULTS In the placenta, S‐100β was localized in villous and intermediate trophoblast cells. The intensity of immunostaining and protein concentration increased with advancing gestation. S‐100β protein was also present in amnion, trophoblast, and decidual cells of fetal membranes, and in endothelial cells of umbilical vessels at all gestational ages. CONCLUSION This study demonstrated that fetoplacental tissues contain S‐100β protein, suggesting that these tissues may, at least in part, be responsible for the high level found in the fetal circulation. Although the significance of placental S‐100β is unknown, this origin should be taken into account when this protein is used as a marker of brain injury in the fetus or infant at birth.

S100B protein in urine of preterm newborns with ominous outcome

Prematurity is an important cause of perinatal death, and no reliable biochemical/biophysical markers exist to identify newborns with an increased mortality risk. We aimed to use S100B concentrations in urine as an early indicator of risk of neonatal death. We did a cross-sectional study using urine obtained from 165 preterm newborns, of whom 11 suffered neonatal death within the first week, 121 displayed no overt neurologic syndrome, and 33 suffered neonatal hypoxia and intraventricular hemorrhage (IVH) but not ominous outcome. Urine S100B concentrations were determined at four time-points and corrected for gestational age by conversion to multiples of median (MoM) of healthy controls of the same gestational age. Ultrasound imaging was assessed within the first 72 h from birth. In infants that died within the first week, S100B levels in urine were already higher than controls at first urination and increased progressively between the 24 and 96-h time-points. Multiple logistic regression analysis showed a significant correlation between urine S100B protein concentrations and the occurrence of neonatal death. An S100B concentration cut-off of 12.93 MoM at first urination had a sensitivity of 100% and a specificity of 97.8% for predicting an ominous outcome. The positive predictive value was 78.6%, the negative predictive value was 100%. Measurement of urine S100B protein levels in preterm newborns could be useful to identify newborns at higher risk of neonatal death.