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?


METHODS
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.
Halis
G
G
Department of Obstetrics and Gynecology, University Hospital Benjamin Franklin, Free University of Berlin, Berlin, Germany. halis@ukbf.fu-berlin.de
Ragosch
V
V
Kuhlmann
K
K
Ebert
A D
AD
Hundertmark
S
S
D000818:Animals; D015152:Blotting, Northern; D003907:Dexamethasone / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000627:therapeutic use; D006801:Humans; D007231:Infant, Newborn; D009924:Organ Culture Techniques; D011247:Pregnancy; D011510:Proteolipids / Q000096:biosynthesis / Q000235:genetics; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012127:Respiratory Distress Syndrome, Newborn / Q000517:prevention & control*; D013970:Thyronines / Q000008:administration & dosage* / Q000627:therapeutic use
D005938:Glucocorticoids; D011510:Proteolipids; D037662:Pulmonary Surfactant-Associated Protein A; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants; D012333:RNA, Messenger; D013970:Thyronines; C022861:3,5-dimethyl-3'-isopropyl-L-thyronine; D003907:Dexamethasone