[Progesterone for Prevention of Preterm Birth--Evidence-based Indications]. / Progesteron zur Prävention der Frühgeburt--Evidenz-basierte Indikationen.

BACKGROUND: The prevention and treatment of preterm birth remains an unsolved problem in modern obstetrics. Progesterone has a variety of actions on the myometrium and the cervix, among others inhibition of myometrial contractility and a cervix strengthening effect by inhibiting the production of proinflammatory cytokines and prostaglandins as well as by reducing the synthesis of proteins, which play a crucial role in initiating labour. Consequently, progesterone may be a promising candidate for the prevention of preterm birth. MATERIAL AND METHODS: We searched PubMed from 1956 to August 2014 using a combination of key words and text words related to preterm birth and progesterone. ('progesterone', progestins, 17-OHPC). The aim of the literature search was to determine evidence-based indications for the use of progesterone in the prevention of preterm birth. RESULTS: (i) Patients with a singleton pregnancy and history of preterm birth should receive vaginal progesterone daily (200 mg capsule or 90 mg containing gel) from 16+0 to 36+0 weeks of gestation (alternatively 250 mg intramuscular 17-OHPC weekly): level of evidence 1a, grade of recommendation ++ . Prophylactic progesterone reduces the incidence of preterm birth <34 and <37 weeks of gestation and perinatal mortality significantly. (ii) Patients with singleton pregnancies and a sonographically short cervix (≤25 mm) before 24 weeks of gestation should receive vaginal progesterone daily (200 mg capsule or 90 mg containing gel) until 36+6 weeks of gestation: level of evidence 1a, grade of recommendation ++ . Prophylactic progesterone leads to a significant reduction in the incidence of preterm birth <28, <33, and <35 weeks of gestation and is associated with a significant reduction of neonatal morbidity. (III) There is a lack of evidence to recommend vaginal progesterone or intramuscular 17-OHPC for primary tocolysis or for "adjunctive" tocolysis (in combination with conventional tocolytic agents). (IV) There is a growing body of evidence that vaginal progesterone (400 mg/day) after successful tocolysis ("maintenance therapy") is a promising option for prolongation of pregnancy: level of evidence 1b, grade of recommendation +. (V) Data from the literature are insufficient to recommend progesterone in patients with preterm rupture of membranes or in the perioperative management of patients requiring transvaginal cervical cerclage. (VI) The vaginal administration of progesterone is well-tolerated by the patients and has only minor maternal side effects, whereas intramuscular injections of 17-OHPC are associated with a significant higher rate of side effects (e. g. local pain, nausea, diarrhoea). It is mandatory to inform patients on the off-label use of progesterone in pregnancy. DISCUSSION: Prophylactic progesterone administration is an evidence-based method for the prevention of preterm birth in women with a previous preterm birth and in pregnant women with a sonographically short cervix (≤25 mm) before 24 weeks of gestation. Vaginal progesterone is favoured over intramuscularly applied 17-OHPC, especially because of the lower rate of maternal side effects. Whether progesterone is an effective approach for the treatment of preterm birth as a tocolytic agent (primary, adjunctive) or for maintenance therapy after arrest of preterm labour has to be shown in further well-designed randomised and controlled trials with adequate statistical power.

Quantifying Paddling Kinematics through Muscle Activation and Whole Body Coordination during Maximal Sprints of Different Durations on a Kayak Ergometer: A Pilot Study.

Paddling technique and stroke kinematics are important performance factors in flatwater sprint kayaking and entail significant energetic demands and a high strength from the muscles of the trunk and upper limbs. The various distances completed (from 200 m to 1000 m) require the athletes to optimize their pacing strategy, to maximize power output distribution throughout the race. This study aimed to characterize paddling technique and stroke kinematics during two maximal sprints of different duration. Nine nationally-trained participants (2 females, age: 18 ± 3 years; BMI: 22.2 ± 2.0 Kg m-1) performed 40 s and 4 min sprints at maximal intensity on a kayak ergometer. The main findings demonstrated a significantly greater mean stroke power (237 ± 80 W vs. 170 ± 48 W; p < 0.013) and rate (131 ± 8 spm vs. 109 ± 7 spm; p < 0.001) during the 40 s sprint compared to the 4 min sprint. Athletes used an all-out strategy for the 40 s exercise and a parabolic-shape strategy during the 4 min exercise. Despite the different strategies implemented and the higher muscular activation during the 40 s sprint, no change in paddling technique and body coordination occurred during the sprints. The findings of the present study suggest that the athletes constructed a well-defined profile that was not affected by fatigue, despite a decrease in power output during the all-out strategy. In addition, they regulated their paddling kinematics during the longer exercises, with no change in paddling technique and body coordination.

[Chemotherapy-induced fetal anemia in maternal acute myelocytic leukemia]. / Chemotherapieinduzierte fetale Anämie bei akuter myeloischer Leukämie der Mutter.

This article discusses the management of a pregnancy of a 32-year-old primigravida with acute myelocytic leukemia treated with induction chemotherapy starting in the 20 + 5 week of gestation. Sonographic monitoring showed evidence of fetal ascites and anemia that could be treated with an intrauterine fetal transfusion. After maternal recovery, a caesarean section was performed in the 27 + 5 week of gestation. We delivered a vivid eutrophic female prematurely. The infant showed persisting signs of myelosuppression. Two further transfusions had to be performed. The present report describes the interdisciplinary therapeutic management when polychemotherapy during pregnancy is necessary for the mother. Cases of acute leukemia in pregnancy are complicated by severe prenatal risks caused by the hematologic illness and by the immediate beginning of chemotherapy. In the third trimester premature delivery is preferable to intrauterine exposition to cytostatic agents. In the second trimester the pregnancy has to be monitored for the typical risks and complications of chemotherapy. Fetal cytotoxic myelosuppression is detectable by prenatal observation so that interventional strategies are feasible.

Cytokeratin antibodies as differential markers of trophoblast and fetomaternal syncytial plaques in the sheep placentome.

The sheep placenta is an often used model in placental research. Uterine epithelium and trophoblast of this synepitheliochorial placenta form a complex, intensely interdigitating epithelial barrier separating maternal and fetal organisms. The close topographical relation and additionally the presence of hybrid syncytia formed by focal fusion of both epithelia hamper identification of the various cellular constituents. Therefore we aimed to find a specific immunohistochemical marker differentiating between the fetomaternal syncytial plaques and trophoblast. A monoclonal antibody directed against type II cytokeratins strongly stained unicellular trophoblast. The syncytial plaques were only weakly stained while binucleate trophoblast remained unstained. This antibody proved to be a useful tool for easy histological orientation in the sheep placenta. In combination with other antibodies in double immunohistochemistry it facilitates exact localization of antigens.

Effects of mild hypothermia on metabolic disturbances in fetal hippocampal slices after oxygen/glucose deprivation depend on depth and time delay of cooling.

OBJECTIVE: There is increasing evidence from animal experiments that mild hypothermia induced during or after cerebral ischemia might protect the immature brain from neuronal cell damage. However, the exact interrelation between the postischemic time delay and the degree of mild hypothermia by which to achieve neuroprotective effects on ischemic insults of different severity has not yet been elucidated systematically. To determine optimal neuroprotection, we studied the interaction between these variables in a recently modified hippocampal slice model. METHODS: We investigated the recovery of energy metabolism and protein synthesis (PSR) in hippocampal slices from mature fetal guinea pigs after 20, 30, or 40 minutes of oxygen and glucose deprivation (OGD). Hypothermia of varying degrees was induced immediately or 2 or 4 hours after OGD and lasted for 12 hours. Prolonged inhibition of PSR after ischemia has been shown to be a sensitive marker of neuronal cell damage. RESULTS: Hypothermia initiated immediately after OGD significantly improved the recovery of energy metabolism and PSR. If there was a 2-hour delay in the onset of hypothermia, neuroprotection depended on the degree of hypothermia. Reduction of the incubation temperature to 31C diminished the disturbances of energy metabolism and PSR, whereas lowering the bath temperature to only 34C was not effective. Hypothermia induced 4 hours after OGD did not have any influence on the recovery of energy metabolism and PSR. CONCLUSION: We conclude that the effects of mild hypothermia on metabolic disturbances in hippocampal slices of mature fetal guinea pigs depended on the intervention delay and the degree of cooling. The shorter the postischemic intervention delay and the greater the degree of hypothermia, the better the neuroprotective effect seems to be.

Circulatory responses to acute asphyxia are not affected by the glutamate antagonist lubeluzole in fetal sheep near term.

OBJECTIVE: Asphyxia is one of the main causes of perinatal brain damage that can result in psychomotor deficits during later development. Recently lubeluzole, a new glutamate antagonist, was shown to improve clinical outcome considerably without any safety concerns in adults who had acute ischemic stroke. However, our preliminary experiments showed transient alterations in heart rate as well as arterial hypertension after intravenous application of this compound in fetal sheep. The aim of the present study was to examine in detail whether lubeluzole affects circulatory responses to acute asphyxia in fetal sheep near term. METHODS: Eleven fetal sheep were chronically instrumented at a mean gestational age of 133 +/- 2 days (term is at 147 days). The fetuses in the study group (n = 6) received three bolus injections of lubeluzole at 30-minute intervals (3 x 0.11 mg/kg estimated body weight), and five controls received solvent. Organ blood flows and physiologic variables were measured before, during, and after arrest of uterine blood flow for 2 minutes (ie, at 0, 1, 2, 3, 4, and 30 minutes). RESULTS: Before asphyxia, distribution of combined ventricular output and physiologic variables in fetuses from the control group were in the normal range for chronically prepared fetal sheep near term. During acute asphyxia there was a redistribution of cardiac output toward the central organs accompanied by pronounced bradycardia and progressive increase in arterial blood pressure. There were nearly no differences between groups in the time course of physiologic and cardiovascular variables measured before, during, and after acute intrauterine asphyxia. CONCLUSION: Lubeluzole did not affect circulatory responses to acute asphyxia in fetal sheep near term.

Endotoxemia severely affects circulation during normoxia and asphyxia in immature fetal sheep.

OBJECTIVE: The purpose of the present study was to determine whether endotoxins (lipopolysaccharides, LPS) affect the fetal cardiovascular system in a way likely to cause brain damage. METHODS: Thirteen fetal sheep were chronically instrumented at a mean gestational age of 107 +/- 1 days. After control measurements of organ blood flow (microsphere method), blood gases, and acid base balance were obtained, seven of 13 fetuses received LPS (53 +/- 3 microg/kg fetal weight) intravenously. Sixty minutes later, asphyxia was induced by occlusion of the maternal aorta for 2 minutes. Measurements of organ blood flows were made at -60, -1, +2, +4, +30, and +60 minutes. RESULTS: Unlike in the control group, after LPS infusion there was a significant decrease in arterial oxygen saturation (-46%; P <.001) and pH (P <.001). In LPS-treated fetuses the portion of combined ventricular output directed to the placenta decreased significantly (-76%; P <.001), whereas output to the fetal body (+60%; P <.001), heart (+167%; P <.05), and adrenals (+229%; P <.01) increased. Furthermore, during asphyxia circulatory centralization was impaired considerably in LPS-treated fetuses, and there was clear evidence of circulatory decentralization. This decentralization caused a severe decrease in cerebral oxygen delivery by 70%. Within 30 minutes after induction of asphyxia five of seven LPS-treated fetuses died, whereas all control fetuses recovered completely. CONCLUSIONS: Endotoxemia severely impaired fetal cardiovascular control during normoxia and asphyxia, resulting in a considerable decrease in cerebral oxygen delivery. These effects might have important effects in the development of fetal brain damage associated with intrauterine infection.

The effects of low-dose endotoxin on the umbilicoplacental circulation in preterm sheep.

OBJECTIVE: In the present study we examined the effects of low-dose endotoxin (lipopolysaccharides, LPS) on continuously recorded umbilical blood flow. METHODS: Twenty fetal sheep were catheterized at a gestational age of 107 +/- 1 days. A flow probe was placed around either the common umbilical artery or one single umbilical artery. Three days later fetuses received either 100 or 500 nanograms of LPS (n = 14) or 2 mL saline (n = 6) intravenously. Six fetuses died within 12 hours after LPS. Fetal heart rate (FHR), mean arterial pressure (MAP), and umbilical blood flow (Q(umb)) were monitored for 3 days. RESULTS: FHR increased by 25 +/- 4% at 4-5 hours after LPS (P <.01) and was elevated for 15 hours after LPS. MAP increased by 18 +/- 5% 1 hour after LPS (P <.01) and returned to control value 4-5 hours after LPS. Q(umb) began to decrease 1 hour after LPS and was minimal (-30 +/- 7%, P <.001) at 4-5 hours after LPS. Q(umb) slowly returned to the control value at 12 hours after LPS. Placental vascular resistance increased by 73 +/- 37% (P <.01), whereas pH did not appreciably change. CONCLUSION: Intravenous application of endotoxin caused a substantial and long-lasting decrease in umbilical blood flow resulting in fetal hypoxemia without acidemia. These effects may be of significance in the development of fetal brain damage associated with intrauterine infection.

The role of nitric oxide on fetal cardiovascular control during normoxia and acute hypoxia in 0.75 gestation sheep.

OBJECTIVE: The role of nitric oxide in control of fetal cardiovascular functions and of cerebral blood flow during normoxia and acute hypoxia is only partially known. We studied the effects of nitric oxide synthase inhibition on the distribution of cardiac output in preterm sheep using N(omega)-nitro-L-arginine methyl ester (L-NAME). METHODS: Thirteen fetal sheep were instrumented at a gestational age of 107 days. Three days later fetuses received L-NAME (n = 7) or vehicle infusion (n = 6). At 0 minutes, acute hypoxia was induced by occlusion of the maternal aorta for 2 minutes. Organ blood flows (microsphere method) and physiologic variables (fetal heart rate, mean arterial pressure [MAP], oxygen saturation, and pH) were measured at -75, -1, +2, +4, and +30 minutes. RESULTS: L-NAME caused bradycardia and an increase in MAP. A significant decrease in cardiac output by 32% occurred in the control group during the control period, which was consequently reflected in organ blood flows. L-NAME injection reduced cardiac output by 64% during normoxia. Blood flow to the fetal body, placenta, and cerebrum decreased by 62%, 66%, and 55%, respectively. During acute hypoxia, L-NAME did not change the redistribution of cardiac output toward the central organs. In the L-NAME group MAP increased, and fetal heart rate was maintained; in contrast, in controls MAP initially decreased and then returned to control values while fetal heart rate decreased. After hypoxia L-NAME delayed the recovery of cardiac output and blunted the increase in blood flow to the brain and heart. CONCLUSIONS: Although influenced by fetal stress after extensive instrumentation, the results of this study indicate that nitric oxide plays a role in fetal cardiovascular control during normoxia and acute hypoxia. Nitric oxide also mediates the increase in blood flow to the brain and heart immediately after hypoxia.

Low-dose flunarizine does not affect short-term fetal circulatory responses to acute asphyxia in sheep near term.

Asphyxia is one of the major causes of perinatal brain damage and neuronal cell loss, which may result in psychomotor deficits during later development. It has been shown previously that the immature brain can be protected from ischemic injury by flunarizine, a class IV calcium antagonist. However, cardiovascular side-effects of flunarizine, when applied at the dosages used in those studies, have been reported. Recently, the present authors were able to demonstrate that even by injecting flunarizine at a far lower dosage (1 mg kg-1 estimated bodyweight) neuronal cell damage, caused by occlusion of both carotid arteries for 30 min, can be reduced in fetal sheep near term. The aim of the present study was, therefore, to examine whether low-dose flunarizine affects fetal cardiovascular responses to acute asphyxia in sheep near term. Ten fetal sheep were chronically instrumented at a mean gestational age of 132 +/- 1 days (term is at 147 days). Fetuses from the study group received a bolus injection of flunarizine (1 mg kg-1 estimated fetal weight) 60 min before asphyxia, whereas the solvent was administered to the fetuses from the control group. Organ blood flows, physiological variables and plasma concentrations of catecholamines were measured before, during and after a single occlusion of uterine blood flow for 2 min (i.e. at 0, 1, 2, 3, 4, and 30 min). Before asphyxia, the distribution of combined ventricular output and physiological variables, as well as concentrations of catecholamines, in fetuses from the control group were in the normal range for chronically prepared fetal sheep near term. During acute asphyxia there was a redistribution of cardiac output towards the central organs accompanied by a pronounced bradycardia and a rapid increase in arterial blood pressure. After asphyxia circulatory centralization did not resolve quite as rapidly as it developed, but was almost completely recovered at 30 min after the insult. There were nearly no differences in the time course of physiological and cardiovascular variables measured before, during and after acute intrauterine asphyxia between the control and study groups. From the present study it was concluded that low-dose flunarizine does not affect short-term fetal circulatory responses to acute asphyxia in sheep near term.

Dynamics of fetal circulatory responses to hypoxia and asphyxia.

This review will focus on the dynamic changes of the fetal circulation, the distribution of organ blood flow during normoxemia, and that during hypoxia and asphyxia caused by various experimental perturbations. Furthermore, the relation between oxygen delivery and tissue metabolism during oxygen lack as well as evidence to support a new concept will be presented along with the principal cardiovascular mechanisms involved. Finally, blood flow and oxygen delivery to the principal fetal organ will be examined and discussed in relation to organ function. The fetal circulatory response to hypoxaemia and asphyxia is a rapid centralization of blood flow in favour of the brain, heart, and adrenals and at the expense of almost all peripheral organs, particularly of the lungs, carcass, skin and scalp. This response is qualitatively similar but quantitatively different under various experimental conditions. However, at the nadir of severe acute asphyxia the circulatory centralization cannot be maintained. Then there is circulatory de-centralization, and the fetus will experience severe brain damage if not expire unless immediate resuscitation occurs. Future work in this field will have to concentrate on the important questions, what factors determine this collapse of circulatory compensating mechanisms in the fetus, how does it relate to neuronal damage, and how can the fetal brain be pharmacologically protected against the adverse effects of asphyxia?

Chorioamnionitis: a multiorgan disease of the fetus?

The bacterial infection of chorion and amnion is a common finding in premature delivery and is referred to as chorioamnionitis. As the mother rarely shows symptoms of a systemic inflammation, the course of chorioamnionitis is frequently asymptomatic and chronic. In contrast, the fetal inflammatory response syndrome represents a separate phenomenon, including umbilical inflammation and increased serum levels of proinflammatory cytokines in the fetus. Ascending maternal infections frequently lead to systemic fetal inflammatory reaction. Clinical studies have shown that antenatal exposure to inflammation puts the extremely immature neonates at a high risk for worsening pulmonary, neurological and other organ development. Interestingly, the presence of chorioamnionitis is associated with a lower rate of neonatal mortality in extremely immature newborns. In the following review, the pathogeneses of inflammation-associated perinatal morbidity are outlined. The concept of fetal multiorganic disease during intrauterine infection is introduced and discussed.

[The treatment with tiparide of the agitation and aggressivity of oligophrenic patients (author's transl)]. / Essai de traitement de l'agitation et de l'agressivité de l'oligophréne par le tiapride.

Tiapride, which is an original medication for the treatment of agitation and psychomotor excitation, was studied in mentally retarded patients; 9 severe and 3 moderate, suffering from bouts of agitation and excitation and aged from 18 to 40 years. The dosage was 4 ampoules (400 mg) daily by IM injection in acute agitation (2 cases), 6 tablets (600 mg) daily in moderately severe cases, and 4 tablets (400 mg) daily in milder cases (4). Very good results were obtained in 3 patients, and good results in 6 others, while no effect was noted in 3 patients (in spite of a reduction in dosage of the other medications). Tolerance was excellent in all cases. Tiapride should fill the therapeutic gap which exists today in the treatment of the agitation and aggressivity of oligophrenia.

Perinatal brain injury.

Perinatal brain damage in the mature fetus is usually brought about by severe intrauterine asphyxia following an acute reduction of the uterine or umbilical circulation. The areas most heavily affected are the parasagittal region of the cerebral cortex and the basal ganglia. The fetus reacts to a severe lack of oxygen with activation of the sympathetic-adrenergic nervous system and a redistribution of cardiac output in favor of the central organs (brain, heart and adrenals). If the asphyxic insult persists, the fetus is unable to maintain circulatory centralization, and the cardiac output and extent of cerebral perfusion fall. Owing to the acute reduction in oxygen supply, oxidative phosphorylation in the brain comes to a standstill. The Na+/K+ pump at the cell membrane has no more energy to maintain the ionic gradients. In the absence of a membrane potential, large amounts of calcium ions flow through the voltage-dependent ion channels, down an extreme extra-/intracellular concentration gradient, into the cell. Current research suggests that the excessive increase in levels of intracellular calcium, so-called calcium overload, leads to cell damage through the activation of proteases, lipases and endonucleases. During ischemia, besides the influx of calcium ions into the cells via voltage-dependent calcium channels, more calcium enters the cells through glutamate-regulated ion channels. Glutamate, an excitatory neurotransmitter, is released from presynaptic vesicles during ischemia following anoxic cell depolarization. The acute lack of cellular energy arising during ischemia induces almost complete inhibition of cerebral protein biosynthesis. Once the ischemic period is over, protein biosynthesis returns to preischemic levels in non-vulnerable regions of the brain, while in more vulnerable areas it remains inhibited. The inhibition of protein synthesis, therefore, appears to be an early indicator of subsequent neuronal cell death. A second wave of neuronal cell damage occurs during the reperfusion phase. This cell damage is thought to be caused by the postischemic release of oxygen radicals, synthesis of nitric oxide (NO), inflammatory reactions and an imbalance between the excitatory and inhibitory neurotransmitter systems. Part of the secondary neuronal cell damage may be caused by induction of a kind of cellular suicide programme known as apoptosis. Interestingly, there is increasing evidence from recent clinical studies that perinatal brain damage is closely associated with ascending intrauterine infection before or during birth. However, a major part of this damage is likely to be of hypoxic-ischemic nature due to LPS-induced effects on fetal cerebral circulation. Knowledge of these pathophysiological mechanisms has enabled scientists to develop new therapeutic strategies with successful results in animal experiments. The potential of such therapies is discussed here, particularly the promising effects of intravenous administration of magnesium or postischemic induction of cerebral hypothermia.

Pathophysiology of perinatal brain damage.

Perinatal brain damage in the mature fetus is usually brought about by severe intrauterine asphyxia following an acute reduction of the uterine or umbilical circulation. The areas most heavily affected are the parasagittal region of the cerebral cortex and the basal ganglia. The fetus reacts to a severe lack of oxygen with activation of the sympathetic-adrenergic nervous system and a redistribution of cardiac output in favour of the central organs (brain, heart and adrenals). If the asphyxic insult persists, the fetus is unable to maintain circulatory centralisation, and the cardiac output and extent of cerebral perfusion fall. Owing to the acute reduction in oxygen supply, oxidative phosphorylation in the brain comes to a standstill. The Na(+)/K(+) pump at the cell membrane has no more energy to maintain the ionic gradients. In the absence of a membrane potential, large amounts of calcium ions flow through the voltage-dependent ion channel, down an extreme extra-/intracellular concentration gradient, into the cell. Current research suggests that the excessive increase in levels of intracellular calcium, so-called calcium overload, leads to cell damage through the activation of proteases, lipases and endonucleases. During ischemia, besides the influx of calcium ions into the cells via voltage-dependent calcium channels, more calcium enters the cells through glutamate-regulated ion channels. Glutamate, an excitatory neurotransmitter, is released from presynaptic vesicles during ischemia following anoxic cell depolarisation. The acute lack of cellular energy arising during ischemia induces almost complete inhibition of cerebral protein biosynthesis. Once the ischemic period is over, protein biosynthesis returns to pre-ischemic levels in non-vulnerable regions of the brain, while in more vulnerable areas it remains inhibited. The inhibition of protein synthesis, therefore, appears to be an early indicator of subsequent neuronal cell death. A second wave of neuronal cell damage occurs during the reperfusion phase. This cell damage is thought to be caused by the post-ischemic release of oxygen radicals, synthesis of nitric oxide (NO), inflammatory reactions and an imbalance between the excitatory and inhibitory neurotransmitter systems. Part of the secondary neuronal cell damage may be caused by induction of a kind of cellular suicide programme known as apoptosis. Knowledge of these pathophysiological mechanisms has enabled scientists to develop new therapeutic strategies with successful results in animal experiments. The potential of such therapies is discussed here, particularly the promising effects of i.v. administration of magnesium or post-ischemic induction of cerebral hypothermia.

Lipopolysaccharides do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs after oxygen-glucose deprivation.

The aim of the present study was to clarify whether endotoxins [lipopolysaccharides (LPS)] have a toxic effect on fetal brain tissue after cerebral ischemia, while excluding their effect on the cardiovascular system. Experiments were therefore performed on hippocampal slices prepared from mature fetal guinea pigs. In particular, we studied the influence of LPS on nitric oxide production, energy metabolism, and protein synthesis after oxygen-glucose deprivation (OGD). Incubating hippocampal slices in LPS (4 mg/L) for as long as 12 h did not alter cGMP tissue concentrations significantly. However, 10 min after OGD of 40-min duration, cGMP tissue concentrations were substantially increased in relation to controls, and this increase was almost completely blocked by the application of 100 microM N:(omega)-nitro-L-arginine, indicating that nitric oxide synthase was activated after OGD in fetal brain tissue. Again, LPS did not have any effect on cGMP tissue concentrations after OGD. Furthermore, addition of LPS altered neither protein synthesis nor energy metabolism measured 12 h after OGD. We therefore conclude that, apart from their well-known influence on the cardiovascular system, LPS do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs 12 h after OGD. A direct toxic effect of LPS on immature brain tissue within this interval does not therefore seem to be very likely. However, delayed activation of LPS-sensitive pathways that may be involved in cell death, or damage limited to a small subgroup of cells such as oligodendrocyte progenitors, cannot be fully excluded.

Low dose flunarizine protects the fetal brain from ischemic injury in sheep.

Flunarizine, a calcium channel blocker, reduced cerebral damage caused by hypoxic-ischemic insults in neonatal rats and in fetal sheep near term. However, the high dose regimen used in these studies produced cardiovascular side effects that might have counteracted the neuroprotective properties of flunarizine. Therefore, the neuroprotective effect was tested in a low dose protocol (1 mg/kg estimated body weight). Twelve fetal sheep near term were instrumented chronically. Six fetuses were pretreated with 1 mg of flunarizine per kg of estimated body weight 1 h before ischemia, whereas the remainder (n=6) received solvent. Cerebral ischemia was induced by occluding both carotid arteries for 30 min. To exclude the possibility that the neuroprotective effects of flunarizine were caused by cerebrovascular alterations we measured cerebral blood flow by injecting radiolabeled microspheres before (-1 h), during (3 min and 27 min) and after (40 min, 3 h, and 72 h) cerebral ischemia. At the end of the experiment (72 h) the ewe was given a lethal dose of sodium pentobarbitone and saturated potassium chloride i.v., and the fetal brain was perfused with formalin. Neuronal cell damage was assessed in various brain structures by light microscopy after cresyl violet/fuchsin staining using a scoring system: 1, 0-5% damage; 2, 5-50% damage; 3, 50-95% damage; 4, 95-99% damage; and 5, 100% damage. In 10 other fetal sheep effects of low dose flunarizine on circulatory centralization caused by acute asphyxia could be excluded. In the treated group neuronal cell damage was reduced significantly in many cerebral areas to varying degrees (range for control group, 1.03-2.14 versus range for treated group, 1.00-1.13; p < 0.05 to p < 0.001, respectively). There were only minor differences in blood flow to the various brain structures between groups. We conclude that pretreatment with low dose flunarizine protects the brain of fetal sheep near term from ischemic injury. This neuroprotective effect is not mediated by changes in cerebral blood flow. We further conclude that low dose flunarizine may be clinically useful as a treatment providing fetal neuroprotection, particularly because the fetal cardiovascular side effects are minimal.