Andres Maturana

Amniotic fluid Clara cell protein concentration in normal pregnancy, a marker of fetal airway growth or fetal lung maturation?

OBJECTIVE:To evaluate the relationship of Clara cell protein (CCP) in amniotic fluid (AF) with the lecithin/sphingomyelin (L/S) ratio, and the concentrations of saturated phosphatidylcholine (Sat PC) and surfactant protein A (SP-A).STUDY DESIGN:AF samples were obtained by amniocentesis from 98 pregnancies without conditions known to influence fetal lung maturation between 25 and 41 weeks of gestation. These samples were used for determinations of CCP, L/S ratio, Sat PC, and SP-A. Simple and multiple linear regressions were used to analyze the data.RESULTS:CCP in AF increased logarithmically with gestational age (R2=0.51, p=0.006). The L/S ratio (R2=0.41, p<0.001), and the concentrations of Sat PC (R2=0.26, p<0.001) and SP-A (R2=0.52, p<0.001) also increased with advancing gestation. Weak correlations of CCP with the L/S ratio (R2=0.22, p=0.009) and Sat PC (R2=0.12, p=0.004), but not with SP-A (R2=0.07, p=0.10), were found. Using multiple linear regressions, gestational age was the only predictor of CCP (F=10.9, R2=0.13, p=0.015). Conversely, gestational age, Sat PC, and SP-A accounted for most of the variation of the L/S ratio (F=34.7, R2=0.61, p=0.0001).CONCLUSION:CCP correlated very poorly with known and widely accepted indices of fetal lung maturation. The increasing concentration of CCP in AF throughout gestation probably reflects growth and development of the fetal airways.

9 |[ldquo]|Meconium Aspiration Syndrome (MAS)|[rdquo]|

Background: The meconium aspiration syndrome (MAS) remains as one of the most frequent causes of respiratory distress in term newborns. Nearly half of these patients require mechanical ventilation; in this group mortality rises to 18%. Some studies have suggested that acute oxygenation parameters benefit when surfactant is used.Methods: We designed a multicenter randomized study to evaluate whether in term newborns with severe MAS, the use of natural surfactant reduces the number of days on mechanical ventilation when compared to placebo.Results and conclusions: No significant differences in any of the outcomes measured were evident. The four existing studies combined show a RR 0.70 (IC 95% 0.50-0.97) for extracorporeal membrane oxygenation (ECMO) requirement or death. With this evidence, deviating resources from the National Surfactant Program to treat MAS should be considered in the context of current healthcare priorities.

Tracheal fluid (TF) saturated phosphatidylcholine (Sat. PC) and surfactant protein A (SP-A) in newborns with congenital diaphragmatic hernia (CDH)† 980

We have reported recently that the amniotic fluid concentrations of the surfactant components Sat. PC and SP-A are decreased in pregnancies with fetuses diagnosed with CDH (Am J Ob Gyn 173:1401, 1995). In addition, it has been suggested that surfactant therapy may be beneficial in the treatment of CDH. However, there is limited data on actual measurements of surfactant components in TF from infants with CDH. The aim of our study was to determine the concentrations of Sat. PC using thin-layer chromatography after osmium tetroxide treatment, and of SP-A by an ELISA method using a rabbit anti-human SP-A polyclonal antibody, in TF obtained during the first day after birth from intubated neonates with CDH (n= 10, mean GA 37.2 weeks, range 29-40 weeks). Also, we made similar determinations in TF samples from preterm infants with respiratory distress syndrome (RDS, n= 10, mean GA 28.4 weeks, range 26-32 weeks) and term neonates intubated for meconium aspiration syndrome (MAS, n=11, mean GA 40.5 weeks, range 37-43 weeks). All cases of CDH occurred on the left side and 6 of them died. Results are shown in the Table as mean ± SEM (* p < 0.05 by Kruskal-Wallis). As we reported previously (Am J Resp Crit Care Med 150:1672, 1994), all infants with RDS had low concentrations of SP-A in TF, compared with none of the neonates with CDH or MAS. Levels of Sat. PC in TF were quite variable and did not differ between groups. The concentrations fo SP-A and Sat. PC were not different in neonates with CDH that survived or died. These data show that deficiency of surfactant components in TF from neonates with CDH is uncommon and does not correlate with outcome.

Response of the Fetal Pituitary-Thiroid Axis (FPTA) To different Doses of Thyrotropin-Releasing Hormone (Trh)

Response of the Fetal Pituitary-Thiroid Axis (FPTA) To different Doses of Thyrotropin-Releasing Hormone (Trh)

Prenatal Corticosteroids (Cs) and Thyroid-Stimulating Hormone (trh) Plus Postnatal Artificial Surfactant In the Prevention of Respiratory Distress Sydrome (Rds) 23

Prenatal glucocorticoids are effective in promoting fetal pulmonary maturation and therefore in preventing RDS. TRH in animals increases the secretion of phospholipids, pulmonary compliance promotes pulmonary morphologic maturation and reduces the passage of proteins to the alveolus. Experimentally TRH+ CS have a synergistic action. Clinical controversy exists in relation to the usefulness of the combined therapy. Primary objective to determine whether prenatal administration of TRH + CS plus postnatal surfactant in pregnancies ≤32 weeks may reduce the incidence of RDS, mortality and chronic lung disease. The secondary objectives referred to complications of RDS. A controlled, double blinded, randomized clinical trial was performed in 8 Clinical Hospitals in Chile, during 3 years. The study group received TRH 400ug: the placebo group normal saline, both diluted in 50ml of normal saline administered in 20-30 minutes IV every 8 hours: 4 doses. Both groups received betamethasone 12mg 1M every 24 hours; 2 doses. All premature infants ≤1000g received surfactant (Exosur). Premature infants< 1000g received surfactant only with clinical evidence of RDS (rescue), with a maximum of 2 doses. Groups were similar in gestational age, birthweight, maternal morbidity, tocolytics, route of delivery, gender, APGAR score and interval from randomisation to delivery. 85-86% received 4 doses of TRH and 86-88% 2 doses of CS. Table

Clara Cell Protein (Cc16) in Amniotic Fluid, A Marker of Fetal Lung. Maturation or Growth?

CC16 is a lung secretory protein mainly produced by clara cells. This has been shown to increase progressively in ammniotic fluid during normal pregnancy and it has also been suggested to be a potential marker of fetal lung growth (Pediatr Res 36:771, 1994). Surfactant protein A (SP-A) on the other hand has proved to be a reliable marker in amniotic fluid of fetal lung maturation. Our purpose was to evaluate the possible correlation between CC16 and other known markers of fetal lung maturation such as SP-A, disaturated phosphatidylcholine (DSPC) and the lecythinsphingomyelin ratio (L/S ratio). We measured amniotic fluid concentrations of CC16, SP-A, DSOC and L/S ratio in 53 pregnancies with normal fetuses at 26-38 weeks gestation; CC16 was measured by immunoassay, SP-A by ELISA using a rabbit anthihuman polyclonal antibody, L/S ratio and DSPC by thin layer chromatography, using osmium tetroxide in the latter. As expected, there is a progressive increase of SP-A, DSPC and L/S ratio with gestational age (SP-A, r=0.41; L/S, r=0.48). The poor correlation with DSPC (r=0.02) is probably due to the fact that the most significant increase in these values takes place at the end of gestation; SP-A as well as DSPC correlate well with L/S ratio (r=0.46, p<0.001 and r=0.46, p<0.001 respectively) while CC16 has a weaker correlation with L/S ratio (r=0.32, p<0.02). In our data CC16 also correlates with gestational age (r=0.30, p=0.02); furthermore using multiple linear regression CC16 does not correlate well with gestational age (r=0.30, p=0.02); furthermore using multiple linear regression Cc16 does not correlate to L/S ratio, DSPC or SP-A but only with gestational age (p=0.017). The different markers of pulmonary maturation in amniotic fluid (SP-A, DSPC and L/S ratio) increase progressively with gestational age. Although CC16 also increase, it does in a different manner with very poor or no relation with the other markers. We speculate that CC16 only reflects lung growth and has no apparent relation with pulmonary maturation (Partially supported with FONDECYT Grant N° 1930854).

AMNIOTIC FLUID CLARA CELL PROTEIN CONCENTRATION IN NORMAL PREGNANCY, A MARKER OF FETAL AIRWAY GROWTH OR FETAL LUNG MATURATION? |[dagger]| 1355

Clara cells protein (CCP) is a lung secretory protein of 16 KD molecular mass that is synthesized by nonciliated bronchial and bronchiolar cells including Clara cells. This protein is produced in the developing fetal airways and can be quantified in amniotic fluid (AF) as early as 15-16 weeks of gestation. The concentration of CCP in AF increases progressively with advancing gestation and has been suggested as a marker of growth of the fetal airways (Pediatr Res 36:771, 1994). However, whether the changes of CCP in AF are also related to the process of fetal lung maturation is unclear. We measured CCP by RIA in 98 AF samples obtained by amniocentesis between 25 and 41 weeks of gestation, from pregnancies without conditions that accelerate or delay fetal lung maturation, and determined its relationship with other known markers of this process. These were the lecithin/sphingomyelin (L/S) ratio determined by thin layer chromatography (TLC), and the concentrations of saturated phosphatidylcholine (Sat PC) measured by TLC after exposure to osmium tetroxide and surfactant protein A (SP-A) quantified by ELISA. With advancing gestational age (GA) the AF concentration of CCP increased slightly(R=0.27, p = 0.006), but more pronounced increases of the L/S ratio (R=0.58, p<0.00001), Sat PC (R=0.45, p <0.0001) and SP-A (R=0.60, p<0.00001) were found. There were extremely weak correlations of CCP with the L/S ratio(R2=0.09, p=0.008) and the AF concentration of Sat PC (R2=0.08, p=0.004), but not with the AF concentration of SP-A (R2=0.02, p=0.10). Using multiple linear regression, the ability to predict changes in the AF concentration of CCP using GA, L/S, Sat PC and SP-A as independent variables was poor (F=3.82, R2=0.19, p=0.007). Conversely, SP-A, Sat PC and GA accounted for most of the variation of the L/S ratio (F=34.71, R2=0.61, p<0.000001). These data suggest that the concentration of CCP in AF has a poor correlation with known indices of fetal lung maturation and probably reflects primarily the development of the fetal airways. (Supported in part by FONDECYT-1930854).