Preeclampsia: an update.
LAMBERT, Géraldine ; BRICHANT, Jean-François ; Hartstein, Gary et al
in Acta anaesthesiologica Belgica (2014), 65(4), 137-49
Preeclampsia was formerly defined as a multisystemic disorder characterized by new onset of hypertension (i.e. systolic blood pressure (SBP) >/= 140 mmHg and/or diastolic blood pressure (DBP) >/= 90 mmHg ... [more ▼]
Preeclampsia was formerly defined as a multisystemic disorder characterized by new onset of hypertension (i.e. systolic blood pressure (SBP) >/= 140 mmHg and/or diastolic blood pressure (DBP) >/= 90 mmHg) and proteinuria (> 300 mg/24 h) arising after 20 weeks of gestation in a previously normotensive woman. Recently, the American College of Obstetricians and Gynecologists has stated that proteinuria is no longer required for the diagnosis of preeclampsia. This complication of pregnancy remains a leading cause of maternal morbidity and mortality. Clinical signs appear in the second half of pregnancy, but initial pathogenic mechanisms arise much earlier. The cytotrophoblast fails to remodel spiral arteries, leading to hypoperfusion and ischemia of the placenta. The fetal consequence is growth restriction. On the maternal side, the ischemic placenta releases factors that provoke a generalized maternal endothelial dysfunction. The endothelial dysfunction is in turn responsible for the symptoms and complications of preeclampsia. These include hypertension, proteinuria, renal impairment, thrombocytopenia, epigastric pain, liver dysfunction, hemolysis-elevated liver enzymes-low platelet count (HELLP) syndrome, visual disturbances, headache, and seizures. Despite a better understanding of preeclampsia pathophysiology and maternal hemodynamic alterations during preeclampsia, the only curative treatment remains placenta and fetus delivery. At the time of diagnosis, the initial objective is the assessment of disease severity. Severe hypertension (SBP >/= 160 mm Hg and/or DBP >/= 110 mmHg), thrombocytopenia < 100.000/muL, liver transaminases above twice the normal values, HELLP syndrome, renal failure, persistent epigastric or right upper quadrant pain, visual or neurologic symptoms, and acute pulmonary edema are all severity criteria. Medical treatment depends on the severity of preeclampsia, and relies on antihypertensive medications and magnesium sulfate. Medical treatment does not alter the course of the disease, but aims at preventing the occurrence of intracranial hemorrhages and seizures. The decision of terminating pregnancy and perform delivery is based on gestational age, maternal and fetal conditions, and severity of preeclampsia. Delivery is proposed for patients with preeclampsia without severe features after 37 weeks of gestation and in case of severe preeclampsia after 34 weeks of gestation. Between 24 and 34 weeks of gestation, conservative management of severe preeclampsia may be considered in selected patients. Antenatal corticosteroids should be administered to less than 34 gestation week preeclamptic women to promote fetal lung maturity. Termination of pregnancy should be discussed if severe preeclampsia occurs before 24 weeks of gestation. Maternal end organ dysfunction and non-reassuring tests of fetal well-being are indications for delivery at any gestational age. Neuraxial analgesia and anesthesia are, in the absence of thrombocytopenia, strongly considered as first line anesthetic techniques in preeclamptic patients. Airway edema and tracheal intubation-induced elevation in blood pressure are important issues of general anesthesia in those patients. The major adverse outcomes associated with preeclampsia are related to maternal central nervous system hemorrhage, hepatic rupture, and renal failure. Preeclampsia is also a risk factor for developing cardiovascular disease later in life, and therefore mandates long-term follow-up. [less ▲]Detailed reference viewed: 42 (18 ULg)
The C-terminal helix of human apolipoprotein AII promotes the fusion of unilamellar liposomes and displaces apolipoprotein AI from high-density lipoproteins.
Lambert, Géraldine ; ; et al
in European Journal of Biochemistry (1998), 253(1), 328-38
To assess the functional properties of apolipoprotein (apo) AII and to investigate the mechanism leading to the displacement of apo AI from native and reconstituted high-density lipoproteins (HDL and r ... [more ▼]
To assess the functional properties of apolipoprotein (apo) AII and to investigate the mechanism leading to the displacement of apo AI from native and reconstituted high-density lipoproteins (HDL and r-HDL) by apo AII, wild-type and variant apo AII peptides were synthesized. The wild-type peptides, residues 53-70 and 58-70, correspond to the C-terminal helix of apo AII and are predicted to insert at a tilted angle into a lipid bilayer. We demonstrate that both the apo AII-(53-70) peptide, and to a lesser extent the apo AII-(58-70) peptide are able to induce fusion of unilamellar lipid vesicles together with membrane leakage, and to displace apo AI from HDL and r-HDL. Two variants of the apo AII-(53-70)-wild-type (WT) peptide, designed either to be parallel to the water/lipid interface [apo AII-(53-70)-0 degrees] or to retain an oblique orientation [apo AII-(53-70)-30 degrees], were synthesized in order to test the influence of the obliquity on their fusogenic properties and ability to displace apo AI from HDL. The parallel variant did not bind lipids, due to its self-association properties. However, the apo AII-(53-70)-30 degrees variant was fusogenic and promoted the displacement of apo AI from HDL. Moreover, the extent of fusion of the apo AII-(53-70)-WT, apo AII-(58-70)-WT and apo AII-(53-70)-30 degrees peptides was related to the alpha-helical content of the lipid-bound peptides measured by infrared spectroscopy. Infrared measurements using polarized light also confirmed the oblique orientation of the helical component of the three peptides. In native and r-HDL, the tilted insertion of the C-terminal helix of apo AII resulting in a partial destabilization of the HDL external lipid layer might contribute to the displacement of apo AI by apo AII. [less ▲]Detailed reference viewed: 20 (0 ULg)
Lipid-binding properties of synthetic peptide fragments of human apolipoprotein A-II.
; Lambert, Géraldine ; et al
in European Journal of Biochemistry (1996), 242(3), 657-64
Human apolipoprotein A-II (apo A-II) consists of three potential amphipathic helices of 17 residues each, which contribute to the lipid-binding properties of this apolipoprotein. The conformation and ... [more ▼]
Human apolipoprotein A-II (apo A-II) consists of three potential amphipathic helices of 17 residues each, which contribute to the lipid-binding properties of this apolipoprotein. The conformation and lipid-binding properties of these peptides, either as single-helix or as two-helix peptides, were investigated by turbidity, fluorescence, electron-microscopy and circular-dichroism measurements, and are compared in this article. The lipid affinity of shorter C-terminal segments of apo A-II was compared with those of the single-helix or two-helix peptides, to define the minimal peptide length required for stable complex formation. The properties of the apo-A-II-(13-48)-peptide were further compared with those of the same segment after deletion of the Ser31 and Pro32 residues, because the deleted apo-A-II-(13-30)-(33-48)-peptide, is predicted to form a long uninterrupted helix. The single helices of apo A-II could not form stable complexes with phospholipids, and the helix-turn-helix segment spanning residues 13-48 was not active either. The apo-A-II-(37-77)-peptide and the apo-A-II-(40-73)-peptide could form complexes with lipids, which appear as discoidal particles by negative-staining electron microscopy. The shortest C-terminal domain of apo A-II able to associate with lipids to form stable complexes was the apo-A-II-(40-73)-peptide, which consisted of the C-terminal helix, a beta-turn and part of the preceding helix. The shorter apo-A-II-(49-77)-peptide, and the helical apo-A-II-(13-30)-(33-48)-peptide, could also associate with phospholipids. The complexes formed were, however, less stable, as they dissociated outside the transition temperature range of the phospholipid. These data suggest that the C-terminal pair of helices of apo A-II, which is the most hydrophobic pair, is responsible for the lipid-binding properties of the entire protein. The N-terminal pair of helices of apo A-II at residues 13-48 does not associate tightly with lipids. The degree of internal similarity and the cooperativity between the helical segments of apo A-II is thus less pronounced than in apo A-I or apo A-IV. The N-terminal and C-terminal domains of apo A-II appear to behave as two distinct entities with regard to lipid-protein association. [less ▲]Detailed reference viewed: 2 (0 ULg)