Impairment of the antiproliferative effect of glucocorticosteroids by 11beta-hydroxysteroid dehydrogenase type 2 overexpression in MCF-7 breast-cancer cells.

To verify the relevance of 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) activity in controlling breast-cancer cell growth, we have evaluated the correlation of 11beta-HSD2 expression and antiproliferative effects of glucocorticosteroids (GCs) on breast cancer cell proliferation. We cloned human 11beta-HSD2 cDNA into the expression vector pBK-CMV. The interspersing lac promoter region was deleted, achieving differential translational efficiency. The constructs were stably transfected into wild-type MCF-7 breast-cancer cells possessing almost no oxidative and no reductive 11beta-HSD activity. Low (times 7) and high (times 718) 11beta-HSD2 overexpression was achieved. We compared growth behavior of transfected cells In the presence of GCs to MCF-7 cells transfected with pBK-CMV alone (internal control). The antiproliferative effects of GCs were reversed and total cell growth boosted by overexpression of 11beta-HSD2; about 50 % of the increase in cell proliferation was attained by low 11beta-HSD2 overexpression, while high enzyme overexpression led to an increase in cell growth of about 120 %. Using direct evidence, this study shows 11beta-HSD2 to impair antiproliferative glucocorticosteroid effects, thus acting as an enzymatic shield aggravating breast-cancer cell growth. These results indicate a possible therapeutic role for 11beta-HSD inhibitors in the treatment of breast cancer.

Limits on diffuse fluxes of high energy extraterrestrial neutrinos with the AMANDA-B10 detector.

Data from the AMANDA-B10 detector taken during the austral winter of 1997 have been searched for a diffuse flux of high energy extraterrestrial muon neutrinos. This search yielded no excess events above those expected from background atmospheric neutrinos, leading to upper limits on the extraterrestrial neutrino flux measured at the earth. For an assumed E-2 spectrum, a 90% classical confidence level upper limit has been placed at a level E2Phi(E)=8.4 x 10(-7) cm(-2) s(-1) sr(-1) GeV (for a predominant neutrino energy range 6-1000 TeV), which is the most restrictive bound placed by any neutrino detector. Some specific predicted model spectra are excluded. Interpreting these limits in terms of the flux from a cosmological distributions of sources requires the incorporation of neutrino oscillations, typically weakening the limits by a factor of 2.

11beta-hydroxysteroid dehydrogenase type 1: a new regulator of fetal lung maturation.

Glucocorticoids (GCs) induce surfactant synthesis in the late fetal lung. Deficient GC action causes respiratory distress syndrome. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inert cortisone (11-dehydrocorticosterone in rodents) into active cortisol (corticosterone), thus amplifying intracellular GC action. We investigated 11beta-HSD1 in the late fetal lung using the licorice-derived inhibitor, glycyrrhetinic acid (GE), in pregnant rats (day 13 of gestation until term). Control fetal mice and rats showed high 11beta-HSD activity in the late fetal lung; levels of plasma 11-dehydrocorticosterone were also high. Reduction/loss of pulmonary 11beta-HSD1 activity in GE-treated rats substantially impaired fetal lung maturation. Lungs from GE-exposed rats had lower surfactant protein-A (mRNA and protein) levels and reduced amniotic fluid lecithin/sphingomyelin ratios. There was a marked depletion of lung surfactant before and after birth, as detected by both light and electron microscopy. The data emphasize the importance of 11beta-HSD1 in amplifying key GC-dependent maturational processes in the late fetal lung.

Foetal lung maturation in 11beta-hydroxysteroid dehydrogenase type 1 knockout mice.

Glucocorticoids (GCs) induce surfactant synthesis in the late foetal lung. Deficient GC action causes respiratory distress syndrome (RDS). 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inert cortisone (11-dehydrocorticosterone in rodents) into active cortisol (corticosterone), thus amplifying intracellular GC action. Reduction or loss of pulmonary 11beta-HSD1 activity in glycyrrhetinic acid-treated rats substantially impaired foetal lung maturation (Hundertmark et al., Horm Metab Res, this issue). To test these data, we investigated 11beta-HSD1 activity and lung maturity in the late foetal lung using 11beta-HSD1 knockout mice. Control foetal mice showed high 11beta-HSD activity in the late foetal lung and levels of plasma 11-dehydrocorticosterone were high. Lungs from 11beta-HSD1 -/- mice had lower surfactant protein-A (mRNA and protein) levels and significant depletion of lung surfactant according to both light and electron microscopy, and also had reduced amniotic fluid lecithin/sphingomyelin ratios. These results support the previous experiments with glycyrrhetinic acid and emphasize the importance of 11beta-HSD1 in foetal lung maturation.

Ontogeny of 11beta-hydroxysteroid dehydrogenase: activity in the placenta, kidney, colon of fetal rats and rabbits.

Mechanisms to regulate closely fetal GC exposure are of considerable importance, as certain organs (kidney, brain) are adversely affected by excess GCs. 11beta-Hydroxysteroid dehydrogenase type 2 (11beta-HSD2) reduces transplacental passage of maternal GCs to the fetus. We hypothesized that 11beta-HSD2, if active in fetal kidney and colon, might allow local tissue modulation of GC access during the critical last trimester. We determined the presence, ontogeny and functionality of 11beta-HSD in the placenta and fetal, neonatal and adult kidney and colon in rats and rabbits and the cortisol:cortisone ratio in human amniotic fluid, which represents fetal urine. There was clear a 11beta-HSD2 expression in last trimester fetal colon, kidney and placenta in both rats and rabbits. This appeared of functional importance, since the potency of cortisol on fetal rabbit colonic sodium flux in the Ussing chamber was increased by 11beta-HSD inhibition. In human amniotic fluid, we found a decreasing ratio of cortisol:cortisone across the last trimester, suggesting an analogous onset of renal 11beta-HSD2 activity in the human fetal kidney. Local fetal tissue 11beta-HSD2 may modulate exposure to the deleterious effects of GCs upon target tissue maturation during sensitive periods of late gestation when fetal GC levels rise to prepare other organs (lung) for adaptations at birth.

Observation of high-energy neutrinos using Cerenkov detectors embedded deep in Antarctic ice.

Neutrinos are elementary particles that carry no electric charge and have little mass. As they interact only weakly with other particles, they can penetrate enormous amounts of matter, and therefore have the potential to directly convey astrophysical information from the edge of the Universe and from deep inside the most cataclysmic high-energy regions. The neutrino's great penetrating power, however, also makes this particle difficult to detect. Underground detectors have observed low-energy neutrinos from the Sun and a nearby supernova, as well as neutrinos generated in the Earth's atmosphere. But the very low fluxes of high-energy neutrinos from cosmic sources can be observed only by much larger, expandable detectors in, for example, deep water or ice. Here we report the detection of upwardly propagating atmospheric neutrinos by the ice-based Antarctic muon and neutrino detector array (AMANDA). These results establish a technology with which to build a kilometre-scale neutrino observatory necessary for astrophysical observations.

Could a combined administration of dexamethasone and 3,5-dimethyl-3'-isopropyl-L-thyronine (DIMIT) be a more effective alternative to dexamethasone alone in the prevention of RDS?

OBJECTIVE: To test whether the combined application of dexamethasone (DEXA) and 3,5-dimethyl-3'-isopropyl-L-thyronine (DIMIT) induces the synthesis of surfactant protein A (SP-A) mRNA at a higher rate than both substances given alone? STUDY DESIGN: Organoid culture of fetal rat lungs (Wistar rats; day 19 of gestation) was prepared. After 48h of incubation we added DEXA (10(-5), 10(-7), 10(-8) and 10(-9)mol/l), DIMIT (10(-5), 10(-7) and 10(-9)mol/l) and the combination of DEXA in 10(-8)mol/l with various concentrations of DIMIT. After another 48h of incubation, northern blot and hybridization with a 32P-labeled SP-A cDNA probe was performed. One-way-variance-analysis with a Scheffé-test, Levene-test and one-sample-t-test were used for statistical analysis. RESULTS: DEXA alone above 10(-8)mol/l resulted in a significant increase, DIMIT resulted in a decrease of SP-A mRNA induction. Combined application of DIMIT and DEXA resulted in a significant increase compared to the controls. Compared to DEXA alone in 10(-8)mol/l, we found an increased induction, but the data were not significant. CONCLUSIONS: The combined application of DEXA and DIMIT shows a higher induction of SP-A mRNA than both drugs given alone.

Kinetic studies on rabbit liver glucocorticoid 5alpha-reductase.

The serum concentration of active glucocorticosteroids depends not only on adrenal synthesis but also on enzymatic activation of 11-dehydro-glucocorticoids in the liver by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). In order to define the respective involvement of other regulative enzymes in the metabolism of 11-dehydro-glucocorticoids in the liver, the objective of this study was to evaluate the kinetic behavior of NADPH:delta 4-3-ketosteroid-5alpha-reductase (5alpha-reductase, EC 1.3.99.5). The interrelations to liver 11beta-HSD1 will be discussed. The kinetic properties of 5alpha-reductase of the rabbit liver were measured by a radioenzymatic assay and characterized with respect to protein-, substrate-, cosubstrate-, and pH-dependence. Michaelis-Menten enzyme kinetic parameters (Km and Vmax) were obtained for the formation of 5alpha-reduced 11-dehydrocorticosterone and corticosterone metabolites. We found that both 11-dehydrocorticosterone (Km 4.2 x 10(-6) mol/l, Vmax 2,600 pmol x min(-1) x mg(-1)) and corticosterone (Km 0.5 x 10(-6) mol/l, Vmax 38 pmol x min(-1) x mg(-1)) exhibit a high affinity to 5alpha-reductase. With respect to cosubstrate-, pH-dependence and finasteride inhibition, it is likely that 11-dehydrocorticosterone metabolism is primarily controlled by isoenzyme 5alpha-reductase type 1. This study shows that the deactivation of GCS especially of 11-dehydro-glucocorticoids via 5alpha-reductase is an important metabolic pathway in the liver. The metabolic activation of GCS by 11beta-HSD could possibly lead to an excess of GCS in the hepatocytes. Due to 5alpha-reductase activity this excess can be limited - on the level of CORT as well as of 11-DHC.

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

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.

Administration of glycyrrhetinic acid: significant correlation between serum levels and the cortisol/cortisone-ratio in serum and urine.

In vitro, cortisol and aldosterone have a similar affinity to the mineralocorticoid receptor. The 11beta-hydroxysteroid dehydrogenase catalyzes the interconversion of cortisol to its inactive 11-oxo-metabolite cortisone. This interconversion is responsible for the in vivo specificity of the mineralocorticoid receptor. A defect of this enzyme leads to a pseudohyperaldosteronism with hypertension and hypokalemia, the so-called apparent mineralocorticoid excess syndrome. Glycyrrhetinic acid, a compound of licorice, also leads to pseudohyperaldosteronism by an inhibition of the 11beta-hydroxysteroid dehydrogenase. We studied the pharmacokinetics of glycyrrhetinic acid and its effect on the 11beta-hydroxysteroid dehydrogenase. Ten healthy students, aged 24 to 38 years, were included in the study. On the first day 500 mg glycyrrhetinic acid were given orally at 08.00 h. Blood and urine samples were taken prior to and 2, 4, 7, 10 and 24 hours after ingestion of glycyrrhetinic acid. We measured the serum level of cortisol, cortisone and glycyrrhetinic acid and the urinary excretion rates of cortisol, cortisone and their 20-dihydrometabolites. For determination of glycyrrhetinic acid and steroid levels we used a fully automated liquid chromatographic analyzer which allows the highly specific and simultaneous determination of steroid profiles even in the matrix of urine. Ratios of the 11-hydroxy- and 11-oxo-metabolites were calculated and correlated to the serum level of glycyrrhetinic acid. We found a significant correlation of the steroid-ratios to the serum levels of glycyrrhetinic acid. Coefficients of correlation were 0.9873, 0.7812, 0.7396 and 0.5844 between the serum level of glycyrrhetinic acid and the cortisol/cortisone-ratio in serum (p < 0.0001), the cortisol/cortisone-ratio in urine (p = 0.0279), the 20alpha-dihydrocortisol/20alpha-dihydrocortisone-ratio in urine (p = 0.0119) and the 20beta-dihydrocortisol/20beta-dihydrocortisone-ratio in urine (p = 0.0419), respectively. We conclude that the ratios of cortisol to cortisone and of the 20-dihydrometabolites of cortisol to the 20-dihydrometabolites of cortisone provide a simple noninvasive tool for monitoring the in-vivo activity of the 11beta-hydroxysteroid dehydrogenase.

Effect of epidermal growth factor on enzymes of phospholipid biosynthesis in lung and liver of fetal rat in vivo and in vitro.

Epidermal growth factor (EGF), a mitogenic polypeptide that binds to cell surface receptors, is an important regulator of cell differentiation and fetal lung surfactant synthesis, and may be used as a potential novel therapeutic agent in prematurity. Nevertheless, the distinct role in lung development and its mechanisms of action are not well understood. We investigated in vivo the systemic effect of intrafetally administered EGF (200 ng/g fetal body weight) and maternally administered dexamethasone (DEXA; 0.2 and 2.0mg/kg maternal body weight) on the activity of important enzymes of the phospholipid synthesis in the fetal rat lung and liver: choline kinase (EC 2.7.1.32), cholinephosphate cytidyltransferase (EC 2.7.7.15), choline phosphotransferase (EC 2.7.8.2), lysolecithin acyltransferase (EC 2.3.1.23) and glycerolphosphate phosphatidyltransferase (EC 2.7.8.5). Additionally, in vivo and in vitro effects of DEXA on EGF receptor synthesis, and the effects of EGF on protein content and morphogenesis of the fetal rat lung organoid culture, were evaluated. Whereas DEXA induced the activity of all investigated enzymes of phospholipid synthesis and increased EGF receptor synthesis, EGF has no effects on the enzymes, either in vivo or in vitro. EGF enhanced protein synthesis and morphogenesis in vitro. With respect to our data and the literature, we hypothesize that DEXA and EGF may act on different cellular sides. Whereas glucocorticoids induce surfactant phospholipid synthesis, EGF should be more involved in cell proliferation and morphogenesis.

Inhibition of 11 beta-hydroxysteroid dehydrogenase activity enhances the antiproliferative effect of glucocorticosteroids on MCF-7 and ZR-75-1 breast cancer cells.

This in vitro study on MCF-7 and ZR-75-1 breast cancer cells showed that the antiproliferative action of glucocorticosteroids (GCS) on breast cancer cells is weakened by a high oxidative activity of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD; EC 1.1.1.146): both endogenic as well as synthetic GCS (dexamethasone, prednisolone) were metabolised to hormonally inactive 11-dehydro metabolites. This enzymatic shield protected the breast cancer cells from the antiproliferative action of GCS. Continuous exposure of breast cancer cells to GCS resulted in enhanced 11 beta-HSD activity. The intracellular GCS concentration was further reduced by this feedback and thus the antiproliferative effect was additionally weakened. These mechanisms of GCS deactivation could be influenced by inhibiting 11 beta-HSD with the liquorice compound glycyrrhetinic acid (GLY). In MCF-7 and ZR-75-1 cultures the antiproliferative effect of GCS was significantly increased by GLY.

Optical properties of deep ice at the South Pole: absorption.

We discuss recent measurements of the wavelength-dependent absorption coefficients in deep South Pole ice. The method uses transit-time distributions of pulses from a variable-frequency laser sent between emitters and receivers embedded in the ice. At depths of 800-1000 m scattering is dominated by residual air bubbles, whereas absorption occurs both in ice itself and in insoluble impurities. The absorption coefficient increases approximately exponentially with wavelength in the measured interval 410-610 nm. At the shortest wavelength our value is approximately a factor 20 below previous values obtained for laboratory ice and lake ice; with increasing wavelength the discrepancy with previous measurements decreases. At ~415 to ~500 nm the experimental uncertainties are small enough for us to resolve an extrinsic contribution to absorption in ice: submicrometer dust particles contribute by an amount that increases with depth and corresponds well with the expected increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The laser pulse method allows remote mapping of gross structure in dust concentration as a function of depth in glacial ice.

[Accuracy of ultrasound weight assessment--comparison of vertex vs. breech presentation]. / Genauigkeit der sonographischen Gewichtsschätzung--Vergleich Schädellage vs. Beckenendlage.

AIM: To determine the quality of prenatal sonographic weight estimation, comparing breech and vertex presentations. METHOD: In 147 breech presentations (BP) and 149 vertex presentations (VP), the biparietal head diameter (BPD), the fronto-occipital head diameter (FOD) and the transverse abdominal diameter (ATD) were measured. From these data, the weight was estimated, using Shepard's formula before 28 weeks and Hansmann's thereafter, and compared to the delivery weight. Both formula were modified to incorporate the virtual BPD (vBPD), derived from the BPD, FOD and the calculated head circumference. In the BP group, the role of examiner skills was evaluated, comparing the accuracy of experienced (DEGUM II qualifications) and average individuals. RESULTS: The accuracy for BP was nearly identical to that for VP (= 0.915 vs. = 0.929). The examiners' qualifications had a detectable but not significant influence on the results (= 0.942 vs. = 0.892). CONCLUSION: Ultrasound measurements yield comparable results in both BP and VP, if the vBPD is used. In our opinion, ultrasonic weight estimation is a useful adjunct when determining the manner of delivery in BP.

[Insulin-like-growth-factor-binding-protein 1 (IGFBP-1) and fetal fibronectin in diagnosis of premature rupture of fetal membranes]. / Insulin like growth factor binding protein 1 (IGFBP-1) und fetales Fibronectin in der Diagnostik eines vorzeitigen Blasensprunges.

The diagnosis of a premature rupture of membranes presents no problem in the vast majority of cases. However, a reliable diagnosis is clinically not possible in about 10%. Most methods available lack the necessary sensitivity and specificity. Since the clinical consequences of a false diagnosis are considerable (overtreatment for false-positive and risk of infection for false-negative results), it is essential to clinically establish new, minimally invasive methods with higher predictive powers. In the present study we compared: the AMNI Check for detection of insulin-like growth-factor binding protein 1 (IGFBP-1); a membrane immunoassay for detection of fetal fibronectin (fFn); pH indicator paper; and, to verify a rupture of membranes in unclear cases, amniocentesis with installation of indigo carmine. The examination was performed in a group of 75 patients, 35 with and 40 without rupture of the membranes. The best results were obtained for the AMNI Check (sensitivity and negative correctness 100%, specificity and positive correctness 83%). With the same sensitivity and negative correctness, the membrane immunoassay for fFn achieved a specificity of 70% and a positive correctness of 74%. The pH indicator paper had the lowest predictive value (sensitivity 94%, negative correctness 93%, specificity 63%, positive correctness 69%). Both the AMNI Check and the test for detection of fetal fibronectin can be recommended for reliable exclusion of premature rupture of membranes. Amniocentesis should however be performed in uncertain cases with a positive test result. Nevertheless, considerable reduction of this invasive method is possible.

[Diagnostic reliability of vaginal ultrasound in ectopic pregnancy]. / Diagnostische Sicherheit der Vaginalsonographie bei ektoper Gravidität.

The therapeutic approach to ectopic pregnancy (EP) has changed over the last decade. A prerequisite for a differentiated management is an early diagnosis of EP. This can be achieved by transvaginal sonography (TVS). The purpose of this study was to evaluate the accuracy of TVS in the diagnosis of EP. 184 patients with clinically suspected ectopic pregnancy were examined by TVS. In 103 cases suspicion of EP was confirmed, in 81 cases it was ruled out. All cases were evaluated by laparoscopy, D&C, serial HCG determinations or sonographic follow-up in case of an intrauterine pregnancy. Sensitivity of TVS in the diagnosis of EP was 96%, specificity 88%, the positive predictive value was 89%, the negative predictive value was 95%. Four cases with a false negative result at TVS were very early in pregnancy and were subjected to laparoscopy because of persistent high HCG values without demonstration of an intrauterine pregnancy. Five cases of sonographically confirmed ectopic pregnancies were missed by the first laparoscopy. These cases required intervention because of clinical symptoms and had low levels of HCG. TVS has a high diagnostic accuracy in the diagnosis of ectopic pregnancy.

[Management of premature rupture of fetal membranes in obstetrical departments in Germany]. / Management des frühen vorzeitigen Blasensprungs an geburtshilflichen Abteilungen in Deutschland.

Since the treatment of premature ruptures of membranes is not only controversial in the German but also in the international literature, we performed a survey of all obstetrics departments in Germany. From a total of 843 hospitals, 444 questionnaires were returned for evaluation (52.7%). The purpose was to determine which diagnostic and therapeutic regimes are used and how these agree with the literature. In addition to questions on the type of hospital, birth rates with a percentage of premature births and applied diagnostic parameters, our special interest focused on therapy, particularly with regard to prophylactic antibiotic application, tocolytic treatment and lung maturity induction. Prophylactic antibiotics are used in 36.7% and prophylactic tocolytic therapy in 41.7% of the departments. Interestingly, lung maturity induction was performed in 93.5%, in part even before the 28th week of pregnancy, although the effect of this therapy has not yet been proven at a very early stage of gestation. Due to the different views in the literature and, in part, a lack of basic scientific data, it seems there is a preference for the procedure, in which the best personal experience has been made. Because premature ruptures of the membranes is responsible for 30-40% of premature births, it is urgently necessary to clarify this controversial problem by large multicenter studies so that the treatment of early premature ruptures of the amnion can be founded on a rational basis.

Correlation of surfactant phosphatidylcholine synthesis and 11 beta-hydroxysteroid dehydrogenase in the fetal lung.

Glucocorticosteroids (GCS) are prerequisite for the induction of surfactant synthesis in the fetal lung. The 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) regulates the intracellular concentration of biologically active GCS. In this study we demonstrate the correlation of 11 beta-HSD activity and the GCS-induced surfactant phosphatidylcholine synthesis in organoid cultures of fetal rat lung. In the first series of experiments, [3H]corticosterone (CORT) or [3H]11-dehydrocorticosterone (11-DHC) were added to lung organoid cultures to test 11 beta-HSD activity. We found a low oxidative and a high reductive conversion indicating that in intact cells the equilibrium tends to biologically active GCS. However, in homogenized organoid cultures oxidative outweighed reductive activity. Secondly, the phosphatidylcholine synthesis of organoid cultures was enhanced by preincubation with GCS. CORT, as well as the hormonally inactive 11-DHC, increased the incorporation of [14C]choline into phosphatidylcholine. The effect of the latter was completely inhibited by glycyrrhetinic acid (inhibitor of 11 beta-HSD) indicating that it is caused by a previous conversion of 11-DHC into CORT via 11 beta-HSD. Thirdly, preincubation with GCS also altered 11 beta-HSD activity: dexamethasone or CORT both decreased the oxidative and increased the reductive activity in intact cells, indicating that glucocorticoids increase the rate of their own activation by positive feedback.

[Prenatal determination of lung maturity from amniotic fluid--indications and new methods]. / Antepartale Lungenreifebestimmung aus dem Fruchtwasser--Indikationen und neue Methoden.

Although fetal lung maturity determination is carried out more and more rarely in the German-speaking area, a reliable information about the degree of lung maturity is still very important in the care of high-risk pregnancies. The side effects and costs of a postpartal surfactant administration can be avoided if lung maturity is proved. Indications for determination of fetal lung maturity are the threatening preterm delivery and the premature rupture of membranes before the 34th week of gestation and uncertain gestational age. Furthermore, in preeclampsia resp. in diabetes mellitus, which is difficult to control, premature delivery may be necessary. To improve lung maturity testing we introduce a new "sequence scheme" containing three lung maturity tests which are easy to carry out (in the following sequence: Amniostat-FLM ultrasensitive, counting of the lamellar bodies in amniotic fluid, surfactant/albumin ratio with TDx-FLM). The principle of this scheme is, that if any of these three tests indicates lung maturity, the sequence is terminated and no further test is performed. Only if all three tests indicated immaturity, the child was at risk for RDS. In 87 amniotic fluid samples with 7 RDS-cases, we achieved high predictive values for lung maturity (specificity 90%, sensitivity 100%, predictive value of positive test 47%, predictive value of negative test 100%). In 62% only one test was needed for lung maturity determination. It is possible to use other combinations in such a scheme (e.g. the L/S ratio). This might lead to equal or perhaps better results. An advantage of this suggested "sequence scheme" is that it can be performed in any clinic.

Gestational age dependence of 11 beta-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.