V. Ragosch

Gestational age dependence of 11β-hydroxysteroid dehydrogenase and its relationship to the enzymes of phosphatidylcholine synthesis in lung and liver of fetal rat

Increase in fetal surfactant synthesis and lung maturity is caused by the glucocorticoidal induction of enzymes required for phosphatidylcholine (PC) synthesis towards the end of gestation. The regulation of gestational age-dependent induction of PC synthesis by glucocorticoids is still unclear. Since 11-beta-hydroxysteroid dehydrogenase (11 beta-HSD) activity and its metabolising capacity for glucocorticoids have been suggested to play a central role in this regulation, we measured the gestational age-dependent changes in 11 beta-HSD and PC synthesizing enzymes in lung and liver of fetal rat. The activity of cholinephosphate cytidyltransferase (CCT; key enzyme in PC synthesis), choline phosphotransferase (CPT) and lysolecithin acyltransferase (LAT) were found to increase gradually in the lung towards the end of gestation, reached peak values at term followed by a decrease of activity reaching finally adult levels. Only CK activity exhibited constant levels until term followed by a slight increase after the birth. In comparison with the lung, the liver enzymes followed a similar pattern, but at a higher rate of activity except for CCT which was higher in the lung. The activity of 11 beta-HSD in fetal lung microsomes was detectable from day 20 and increased towards the end of gestation in the lung and liver of the rat. Oxidase activity was always found to exceed the reductase activity. The activity of 11 beta-HSD continued to increase after delivery and reached peak levels in adult animals in both organs. In order to test the hypothesis, whether 11 beta-HSD activity and PC synthesis are induced by increasing endogenous glucocorticoidal levels, we examined on day 19 of gestation the effect of dexamethasone (DEXA) on enzymatic activities (11 beta-HSD, CCT) and on [14C]choline incorporation in phosphatidylcholine in fetal lung organoid cultures. Additionally, changes in CCT activity in fetal lungs after maternal administration of DEXA were measured. DEXA accelerated 11 beta-HSD and CCT activities as well as [14C]choline incorporation. We conclude, that endogenous glucocorticoids induce PC synthesis as well as 11 beta-HSD activity in lung and liver of the fetal rat. Fetal PC synthesis is not altered by increasing 11 beta-HSD levels, because the increase of free serum corticosterone levels apparently exceeds the metabolising capacity of 11 beta-HSD towards term.

Evaluation of the fetal assessment score in pregnancies at risk for intrauterine hypoxia

OBJECTIVE Our purpose was to define the diagnostic value of a new fetal assessment score that is based on each of the components of the Apgar score. STUDY DESIGN A fetal assessment score was established to study the main fetal vital functions: (1) cardiovascular (heart rate, color of the skin in the Apgar score), now based on fetal heart rate patterns and Doppler assessment of fetal blood flow redistribution, (2) fetal respiratory (quality of breathing in the Apgar score), now based on Doppler assessment of uteroplacental perfusion, and (3) neuromuscular function (tone and reflexes in the Apgar score), now based on fetal tone and response to external stimuli. The fetal assessment score was used in the study of 110 postdate pregnancies and 103 small-for-gestational-age infants and was compared with the traditional biophysical profile score in the prediction of perinatal outcome. RESULTS There were significant associations between both the fetal assessment score and the biophysical profile score with fetal distress that necessitated operative delivery, low Apgar scores, and low umbilical cord arterial blood pH. However, receiver-operator characteristic plots demonstrated that the fetal assessment score was superior to the biophysical profile score in predicting fetal distress and low Apgar values particularly in the small-for-gestational-age infants. The best single parameters in predicting fetal distress were the amniotic fluid volume in the biophysical profile score and fetal heart rate patterns and pulsed Doppler measurements in the new score. CONCLUSION A fetal Apgar score in which respiration is assessed by placental perfusion rather than chest movements and in which skin color is assessed by centralization of fetal blood flow may be better than the traditional biophysical profile score in predicting fetal hypoxic compromise.

Indication and results of insulin therapy for gestational diabetes mellitus

The aim of this study was to determine whether amniotic fluid insulin concentration (AFI) is a better parameter than mean maternal blood glucose values (MBG) for deciding about insulin therapy in patients with gestational diabetes. MBGs were calculated on the base of 9 blood glucose levels during a 24 hour period after one week of diet therapy. In a prospective trial between 1987 and 1989 in Karlsburg, 123 gestational diabetic patients were randomized into two groups. Treatment was either based on the concentration of AFI or MBG levels. In a second series in Berlin, 103 patients were offered amniocentesis. 81 patients agreed and 22 refused. Treatment was then analogous to that in Karlsburg. In both groups of the randomized population, strict metabolic control was achieved. There was no difference regarding pregnancy complications. Earlier labor induction and higher cesarean section rates were seen in the non-invasive group (p < 0.05). The incidence of diabetic fetopathy and neonatal hypoglycemia was significantly lower in the invasive group (p < 0.01), even though the metabolic control parameters did not differ between the two groups. The results in Berlin correspond to these findings. In conclusion, AFI enables the recognition of any hyperinsulinism reaction to the maternal metabolic situation. We recommend the additional measurement of the AFI concentration between 28 and 36 weeks as the direct fetal parameter for deciding about insulin treatment.

Effect of dexamethasone, triiodothyronine and dimethyl-isopropyl-thyronine on lung maturation of the fetal rat lung.

Abstract Our purpose was to elucidate why clinical studies have up to now failed to demonstrate a positive effect of TRH combined with glucocorticosteroids on fetal lung maturity. Morphological and biochemical lung maturation were determined by electron microscopy, choline incorporation, and surfactant-protein-A m-RNA synthesis in rat lung organoid cultures after exposure with a series of concentrations of dexamethasone, triiodothyronine, and dimethyl-isopropyl-thyronine. Thyroid hormones improved morphogenesis of lung histotypic structures but had a negative effect on surfactant synthesis whereas glucocorticosteroids had a positive effect on the surfactant synthesis but a negative effect on morphogenesis. The combination of both substances even had the most negative effect on morphogenesis. Since morphogenesis of lung histotypic structures is prerequisite for surfactant synthesis and secretion, we hypothesize that a sequential treatment of thyroid hormones to improve morphogenesis followed by the application of glucocorticosteroids might be an option to improve neonatal lung function.

Prediction of RDS by amniotic fluid analysis: a comparison of the prognostic value of traditional and recent methods.

The determination of lecithin or even more the lecithin/sphingomyelin (L/S) ratio in amniotic fluid are both well established in the prediction of neonatal RDS. The immunological measurement of phosphatidylglycerol (PG) and the determination of the surfactant/albumin (S/A) ratio by fluorescence polarization (TDx FLMR) have recently been introduced for the detection of fetal lung maturity. In order to compare traditional versus recent methods L/S ratio and PG determination by one dimensional thin-layer chromatography, enzymatic analysis of lecithin, immunological determination of PG by Amniostat-FLMR and the fluorescence polarization of S/A-ratio by the TDx FLMR were all performed in 141 amniotic fluid samples of 122 patients. Only one out of 72 samples was false negative in the enzymatic lecithin determination (sensitivity 88%). All other methods have a sensitivity and a negative predictive value of 100%. The positive predictive values and the specificity varied between 22%-50% and 58%-87% respectively. The false positive rate, which is high for all methods, is lowest for the L/S ratio. This study demonstrates, that the recent methods are reasonable alternatives in all cases with a positive test. In clinical practice they have the advantage, that the result can be obtained in 15 minutes. If the test is predictive for lung immaturity the L/S ratio should be performed in addition to decrease the false positive rate before any clinical decision is made.

11-Beta-hydroxysteroid dehydrogenase of rat lung : enzyme kinetic, oxidase-reductase ratio, electrolyte and trace element dependence

The modulation of the intracellular glucocorticoidal effect on surfactant synthesis of the fetal lung by the metabolic capacity of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) could be an important factor in lung maturation. The kinetic properties of microsomal 11 beta-HSD of the rat lung are characterized with respect to product inhibition, substrate specificity, effect of electrolytes or trace elements, and the dependence of the oxidase reductase (OR) ratio on incubation conditions. With NADP+ product inhibition of the reductase was demonstrated. The most common trace elements and electrolytes exhibited no effect on the activity of 11 beta-HSD. It is shown that the OR ratio was strongly dependent on assay conditions. With optimal assay conditions oxidase activity exceeds reductase activity in adult and fetal rat lung microsomes (OR ratio > 1). Thus, glucocorticoids are mainly metabolized to their inactive forms. The enzyme activity in the adult is about 10 times higher than in the fetal lung. The low enzyme activity in fetal lungs could be the reason why the glucocorticoidal effects on surfactant synthesis are not suppressed despite the predominance of oxidase activity.

Die imminente Frühgeburt als Notfall

ZusammenfassungEtwa 2/3 der Neonatalsterblichkeit ist Folge der Frühgeburtlichkeit. Ein wesentlicher bisher wenig beachteter Faktor ist die Notwendigkeit der Qualitätssicherung für die Erkennung und Erstbehandlung der imminenten Frühgeburt.Ärzte, die im Rahmen der Primärversorgung von Schwangeren mit fraglichen Frühgeburtsbestrebungen die Entscheidung zwischen rechtzeitiger intrauteriner Verlegung oder Möglichkeit der weiterer Betreuung zu treffen haben, nehmen eine große Verantwortung auf sich. Die zu großzügige Verlegung in Zentren ist mit unnötigen Kosten und Verängstigung der Schwangeren verbunden. Eine zu zurückhaltende Verlegungspraxis kann zu Notsituationen führen, die die Prognose der Kinder verschlechtern.Allgemeingültige Handlungsrichtlinien für eine sinnvolle diagnostische und therapeutische Kaskade in dieser Situation sind schwierig zu erstellen. Ein individuell erstellter Notfallplan ist hier sinnvoll, wobei die wichtigste Maßnahme bei tatsächlich drohender Frühgeburt eine zügig organisierte ärztlich begleitete Verlegung der Schwangeren in ein Krankenhaus der Maximalversorgung ist. Die Durchführung weiterer Basismaßnahmen (Lungenreifeinduktion, Tokolyse, Antibiotika, evtl. Entbindung vor Ort unter Hinzuziehung eines Neonatologen) ist abhängig vom Befund, dem Schwangerschaftsalter und den lokalen Möglichkeiten individuell für die Situation zu indizieren.Auf der Basis der aktuellen Erkenntnisse werden nachfolgend Empfehlung für diese Maßnahmen gegeben.AbstractApproximately two-thirds of neonatal mortalities are due to premature birth. An essential factor that has thus far received inadequate attention is the necessity to perform quality monitoring for the recognition and first treatment of imminent premature birth.Physicians accept great responsibility when called upon to decide between timely intrauterine transfer and continued care in the primary management of pregnant women with signs of premature labor. Overly liberal transfer to level III centers involves unnecessary costs and adds to the anxiety of the expectant mothers. A too restrictive transfer practice can lead to emergency situations that worsen the prognosis of the children. It is difficult to establish universally valid guidelines for a meaningful diagnostic and therapeutic cascade in this situation.An individual emergency plan makes sense here, the most important measure being a quick, medically supervised transfer to a level III hospital in cases of imminent premature birth. The indication for further basic procedures (e.g., lung maturity induction, tocolysis, antibiotics, on-the-spot delivery with neonatological consultation) should be individually established according to the results, the gestational age, and the local facilities. Recommendations for these procedures are based on the current state of the art.

Wirkung von Aminophyllin auf die Surfaktant-Biosyntbese am Tiermodell der fetalen Ratte

Zur Prophylaxe des Atemnotsyndroms wird seit Jahren nach Alternativen und zusatzlichen Therapieformen zur herkommlichen Glukokortikoidtherapie gesucht. Die Wirkung von Aminophyllin auf die biochemischen Mechanismen der fetalen Lungenreife sind bisher nicht hinreichend geklart. Wir benutzten das Tiermodell der fetalen Ratte, um die Wirkung von Aminophyllin auf die Enzyme der Synthese des Surfaktantphos- pholipids Phosphatidylcholin zu untersuchen.

Bestimmung der „Lamellar Bodies“ im Fruchtwasser als neue Methode der Vorhersage eines neonatalen Atemnotsyndroms

Zur Bestimmung der fetalen Lungenreife stehen biochemische und biophysikalische Methoden zur Verfugung, die direkt oder indirekt den Phospholipidgehalt des Fruchtwassers messen (1).

Organoidkultur der fetalen Rattenlung als Modell zur In-vitro Testung Surfaktant-induzierender Substanzen

Organoidkulturen bieten ein in vitro System in dem sich lungengewebeahnliche Strukturen ausbilden und Surfaktant produziert wird. Die Enzyme der Phopholipidsynthese zeigen im Zellkulturalter charakteristische Aktivitatsverlaufe. Die Maxima finden sich am 3. - 5 Kulturtag.