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McDougall ARA, Fosang AJ, Faggian J, Wallace MJ, Crossley KJ, Cole TJ, Hooper SB. Glucocorticoids influence versican and chondroitin sulphate proteoglycan levels in the fetal sheep lung. Respir Res 2018; 19:155. [PMID: 30126423 PMCID: PMC6102879 DOI: 10.1186/s12931-018-0854-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 08/01/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prenatal glucocorticoid treatment decreases alveolar tissue volumes and facilitates fetal lung maturation, however the mechanisms responsible are largely unknown. This study examines whether changes in versican levels or sulphation patterns of chondroitin sulphate (CS) side chains, are associated with glucocorticoid-induced reductions in peri-alveolar tissue volumes. METHODS Lung tissue was collected from 1) fetal sheep at 131 ± 0.1 days gestational age (GA) infused with cortisol (122-131d GA) to prematurely induce a pre-parturient-like rise in circulating cortisol, 2) fetal sheep at 143d GA bilaterally adrenalectomised (ADX) at 112d GA to remove endogenous cortisol and 3) fetal sheep at 124d GA in which bolus doses (2 × 11.4 mg) of betamethasone were administered to the pregnant ewe. The level and distribution of versican and CS glycosaminoglycans (GAG) were determined using immunohistochemistry (IHC). Fluorophore assisted carbohydrate electrophoresis (FACE) was used to determine changes in CS sulphation patterns. RESULTS Cortisol infusion significantly decreased chondrotin-6-sulphate levels (C-6-S) to 16.4 ± 0.7 AU, compared with saline-infused fetuses (18.9 ± 0.7 AU: p = 0.04) but did not significantly alter the level of versican or chondroitin-4-sulphate (C-4-S). ADX significantly increased the level of C-4-S (28.2 ± 2.2 AU), compared with sham-operated fetuses (17.8 ± 2.0 AU; p = 0.006) without altering versican or C-6-S levels. Betamethasone significantly decreased versican, C-4-S and C-6-S in the fetal sheep lung (19.2 ± 0.9 AU, 24.9 ± 1.4 AU and 23.2 ± 1.0 AU, respectively), compared with saline-exposed fetuses (24.3 ± 0.4 AU, p = 0.0004; 33.3±0.6 AU, p = 0.0003; 29.8±1.3 AU, 0.03, respectively). CONCLUSIONS These results indicate that glucocorticoids alter versican levels and CS side chain microstructure in alveolar lung tissue. Betamethasone appears to have a greater impact on versican and CS side chains than cortisol.
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Affiliation(s)
- Annie R A McDougall
- The Ritchie Centre, The Hudson Institute of Medical Research, 27-31 Wright Street, Clayton, VIC, 3168, Australia.
| | - Amanda J Fosang
- Arthritis Research Group, Department of Pediatrics, University of Melbourne and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, 3052, Australia
| | - Jessica Faggian
- The Ritchie Centre, The Hudson Institute of Medical Research, 27-31 Wright Street, Clayton, VIC, 3168, Australia.,Arthritis Research Group, Department of Pediatrics, University of Melbourne and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, 3052, Australia
| | - Megan J Wallace
- The Ritchie Centre, The Hudson Institute of Medical Research, 27-31 Wright Street, Clayton, VIC, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, 3800, Australia
| | - Kelly J Crossley
- The Ritchie Centre, The Hudson Institute of Medical Research, 27-31 Wright Street, Clayton, VIC, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, 3800, Australia
| | - Timothy J Cole
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, 3800, Australia
| | - Stuart B Hooper
- The Ritchie Centre, The Hudson Institute of Medical Research, 27-31 Wright Street, Clayton, VIC, 3168, Australia.,Department of Obstetrics and Gynaecology, Monash University, Melbourne, VIC, 3800, Australia
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Smart DE, Princivalle MB. Improving RDS treatment with current drugs. J Matern Fetal Neonatal Med 2011; 25:1209-11. [DOI: 10.3109/14767058.2011.634456] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Debeer A, Flemmer AW, Lewi PJ, Beheydt S, De Buck F, Zimmermann LJ, Naulaers G, Deprest JA. Preterm rabbit lung tissue mechanics: maturational changes and effect of antenatal steroids. Pediatr Pulmonol 2010; 45:349-55. [PMID: 20232469 DOI: 10.1002/ppul.21191] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
AIM Describe lung tissue and central airway mechanics using forced oscillation in preterm rabbits at different gestational ages and after maternal administration of betamethasone (BM). METHODS One hundred twelve fetuses from 54 does were studied. Ventilation was done using a Flexivent (Scireq, Montreal, Canada). Resistance (Rrs), compliance/bodyweight (Crs/bw), Newtonian resistance (Rn), tissue damping (G(L)), and elastance (H(L)) were assessed. Maturational changes were studied in normal controls at days 27-31. The effect of BM (0.05 mg/kg on days 25 and 26) or placebo was studied in preterm fetuses at days 27, 28, and 29. RESULTS In unmanipulated control fetuses, Rrs decreased and Crs/bw increased with advancing gestation. Rn remained stable while G(L) and H(L) decreased. After day 29 no differences in pulmonary mechanics were observed. At 28 days Rrs and Crs/bw in BM and placebo fetuses were better compared to controls. At 29 days, Crs/bw and Rrs were higher, respectively, lower in control fetuses than BM or placebo exposed pups. CONCLUSION Maturational changes in preterm rabbits occur mainly up to day 29 of gestation and are largely due to changes in tissue mechanics. Maternal BM injection improves lung mechanics at 28 days but placebo has equal effects.
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Affiliation(s)
- Anne Debeer
- Centre for Surgical Technologies, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium
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Okajima S, Matsuda T, Cho K, Matsumoto Y, Kobayashi Y, Fujimoto S. Antenatal dexamethasone administration impairs normal postnatal lung growth in rats. Pediatr Res 2001; 49:777-81. [PMID: 11385137 DOI: 10.1203/00006450-200106000-00011] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Our purpose was to determine the influences of antenatal dexamethasone administration on neonatal lung development in rats. Dexamethasone (0.4 mg/kg maternal body weight per day) was administered i.p. on the 21st d (group 1) or on the 20th and 21st d (group 2) of gestation in Sprague Dawley rats with timed pregnancies. After natural deliveries, the lungs of the pups 1-60 d of age were removed and processed for morphometric analysis. In 60-d-old pups, groups 1 and 2 both showed a lower numerical density of alveoli and a larger mean alveolar radius than control pups. Antenatal administration of dexamethasone to rats impairs the normal postnatal lung growth. Some aspects of the use of antenatal glucocorticoid therapy in humans may require reconsideration.
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Affiliation(s)
- S Okajima
- Department of Pediatrics, Hokkaido University Hospital, Hokkaido University School of Medicine, Sapporo 060-8638, Hokkaido, Japan.
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Kapur P, Holm BA, Irish MS, Sokolowski J, Patel A, Glick PL. Lung physiological and metabolic changes in lambs with congenital diaphragmatic hernia after administration of prenatal maternal corticosteroids. J Pediatr Surg 1999; 34:354-6. [PMID: 10052822 DOI: 10.1016/s0022-3468(99)90208-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND/PURPOSE Improved outcomes of preterm infants born to mothers treated prenatally with corticosteroids have been documented. The authors investigated the role of prenatal maternal corticosteroid therapy in congenital diaphragmatic hernia (CDH). METHODS Five CDH lambs of ewes given 0.5 mg/kg betamethasone intravenously 24 hours before delivery (single-dose), four CDH lambs of ewes similarly dosed at 48 and 24 hours before delivery (double-dose), five untreated CDH lambs and five control lambs were studied. After 2 hours of ventilation, compliance, arterial oxygen (PO2) and carbon dioxide (pCO2) concentrations were recorded. Lavage protein and phospholipid levels were measured, and lung tissue was analyzed for antioxidant enzyme activity (AOE). RESULTS No improvement in gas exchange was noted in either treatment group. Significant increases in compliance (P = .02) were noted in the double-dose steroid group, which were different from that of untreated CDH lambs or controls. Minimal changes in AOE activities were seen with steroid administration. CONCLUSIONS Although the metabolic changes were not significant, the marked improvement in compliance seen in the double-dosed steroid group suggests a potential role for prenatal maternal corticosteroids in CDH. Further timing and dosage studies are warranted in this model.
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Affiliation(s)
- P Kapur
- The Buffalo Institute of Fetal Therapy, Children's Hospital of Buffalo, and the Department of Pediatric Surgery, State University of New York at Buffalo, School of Medicine and Biomedical Sciences, 14222, USA
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Boland RE, Nardo L, Hooper SB. Cortisol pretreatment enhances the lung growth response to tracheal obstruction in fetal sheep. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 273:L1126-31. [PMID: 9435566 DOI: 10.1152/ajplung.1997.273.6.l1126] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We have investigated whether cortisol pretreatment of sheep fetuses will result in a greater liquid accumulation within the lung and a greater lung growth response to obstruction of the fetal trachea. Chronically catheterized fetal sheep received either 1) a cortisol infusion at an increasing dose (1.5-4.0 mg/day) from days 118 to 127 of gestation; the fetal trachea was then obstructed from days 128 to 131 of gestation (n = 4); 2) a saline infusion from days 118 to 127 of gestation; the fetal trachea was then obstructed from days 128 to 131 of gestation (n = 4); or 3) a saline infusion from days 118 to 127 of gestation with no period of tracheal obstruction (control; n = 4). Fetal tracheal pressures were measured from days 128 to 131 of gestation, whereas lung liquid secretion rates and volumes were measured on days 118, 128, and 131 of gestation. On day 131 of gestation, all fetuses were given an intravenous injection of [3H]thymidine and were killed 8 h later. Cortisol pretreatment increased the volume of liquid that accumulated within the fetal lung from 69.5 +/- 4.1 to 96.1 +/- 14.1 ml/kg after 3 days of tracheal obstruction. Similarly, cortisol pretreatment significantly enhanced the increase in lung DNA content from 257.4 +/- 11.0 to 309.1 +/- 16.3 mg/kg after 3 days of tracheal obstruction. We conclude that pretreatment of fetuses with cortisol increases the volume of liquid that accumulates after tracheal obstruction and, as a result, increases the fetal lung growth response to tracheal obstruction.
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Affiliation(s)
- R E Boland
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Lacaze-Masmonteil T. [Prenatal corticotherapy and acceleration of fetal maturation. II. Results of clinical applications]. Arch Pediatr 1996; 3:1119-28. [PMID: 8952778 DOI: 10.1016/s0929-693x(96)89520-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Numerous subsequent controlled trials and recent meta-analysis have confirmed the efficiency of antenatal glucocorticoid therapy in reducing both the incidence of respiratory distress syndrome (RDS) and perinatal mortality. Moreover, antenatal glucocorticoid administration reduces the odds of several severe complications relating to immaturity: intraventricular hemorrhage (IVH), ductus arteriosus patency, necrotising enterocolitis, and hemodynamic failure. Exogenous surfactant therapy has not ruled out the benefits of corticosteroids: on the contrary, a synergic effect is obtained when both antenatal and postnatal therapeutic approaches are combined. Very premature infants may also take advantage of the hormonal treatment: in this population, RDS occurrence, IVH incidence and perinatal mortality are also reduced. Unfortunately, despite convincing evidence, the incidence of antenatal steroids therapy has not yet achieved the optimal and desirable level. Obstetricians and pediatricians must be encouraged to ensure high maternal exposure to steroids when preterm delivery is likely to occur.
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Affiliation(s)
- T Lacaze-Masmonteil
- Service de médecine et réanimation néonatales, hôpital Antoine-Béclère, Clamart, France
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Moraga FA, Riquelme RA, López AA, Moya FR, Llanos AJ. Maternal administration of glucocorticoid and thyrotropin-releasing hormone enhances fetal lung maturation in undisturbed preterm lambs. Am J Obstet Gynecol 1994; 171:729-34. [PMID: 8092222 DOI: 10.1016/0002-9378(94)90089-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE We hypothesized that combined treatment with glucocorticoid plus thyrotropin-releasing hormone administered to pregnant ewes with preterm gestation accelerates fetal lung maturation of undisturbed lambs better than single hormonal treatment does. STUDY DESIGN Twenty-five pregnant ewes at 123 days of gestation were randomized to receive (1) 0.9% sodium chloride (controls), (2) betamethasone (12 mg intramuscularly every 24 hours two times), (3) thyrotropin-releasing hormone (400 micrograms intravenously every 8 hours six times), or (4) thyrotropin-releasing hormone plus betamethasone. After delivery by cesarean section at 125 days fetal lamb lung compliance and alveolar lavage phospholipid content were determined. RESULTS Betamethasone plus thyrotropin-releasing hormone significantly increased fetal lung compliance expressed as milliliters of air per gram of wet weight at 40 cm H2O and 5 cm H2O (0.82 +/- 0.13 and 0.35 +/- 0.10 ml/gm wet lung, respectively) versus betamethasone (0.37 +/- 0.02 and 0.07 +/- 0.02), thyrotropin-releasing hormone (0.38 +/- 0.02 and 0.14 +/- 0.03), and control (0.25 +/- 0.03 and 0.09 +/- 0.01) groups. Also, total phospholipids and saturated phosphatidylcholine concentrations in alveolar lavage were significantly higher in the combined betamethasone plus thyrotropin-releasing hormone group (27.3 +/- 4.9 and 16.9 +/- 4.3 micrograms/gm wet lung, respectively) versus betamethasone (10.9 +/- 3.5 and 6.7 +/- 2.1), thyrotropin-releasing hormone (15.2 +/- 5.6 and 7.3 +/- 2.0), and control (7.9 +/- 2.4 and 3.6 +/- 1.0) groups. CONCLUSION Combined maternal administration of betamethasone plus thyrotropin-releasing hormone improves lung maturation in undisturbed fetal lambs at 125 days' gestation more than does either hormone given alone.
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Affiliation(s)
- F A Moraga
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad de Chile, Santiago
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Affiliation(s)
- G C Liggins
- Research Centre in Reproductive Medicine, University of Auckland, New Zealand
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Abstract
OBJECTIVE We evaluated the effect of maternal administration of betamethasone (0.2 mg/kg per day) on mitogen-induced lymphocyte proliferation and interleukin-2 (IL-2) production by maternal, fetal, and neonatal rat splenic lymphocytes. STUDY DESIGN Betamethasone was injected intramuscularly on days 19 and 20 of gestation to timed-pregnant rats (Sprague-Dawley). Fetuses were delivered on day 21 of gestation, or allowed to deliver spontaneously at term (22 days), followed by sacrifice at various intervals after birth. Lymphocyte proliferation was determined by 3H-thymidine incorporation with and without phytohemagglutinin (PHA), and IL-2 by proliferation of IL-2 dependent CTLL-2 cells. RESULTS Maternal lymphocytes had higher spontaneous proliferation than lymphocytes from nonpregnant female rats. Betamethasone use resulted in a decrease in PHA-induced lymphocyte proliferation and IL-2 production by maternal lymphocytes. These effects were observed until 4 days after delivery. Significant decreases in these parameters were also seen in 21-day fetuses of betamethasone-treated mothers. These effects were still present 6 days after birth but not at 12 days of age. CONCLUSION These findings suggest that, in the rat, exposure to betamethasone during late pregnancy results in marked, but transient decreases in PHA-induced lymphocyte proliferation and IL-2 production in both the mothers and their offspring.
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Affiliation(s)
- K K Murthy
- Department of Pediatrics, Louisiana State University Medical Center, New Orleans
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Abstract
Two main strategies are available for the prevention of neonatal respiratory distress syndrome (RDS) in cases of preterm delivery: antenatal administration of hormones that accelerate fetal lung maturation, and prophylactic treatment with surfactant soon after birth. The efficacy of each of these therapeutic regimens has been well documented in large randomized clinical trials, and recent data furthermore indicate that, in preterm babies with lowered risk of RDS after antenatal corticosteroid treatment, the odds for developing RDS are not further reduced by prophylactic treatment with surfactant. Corticosteroids and surfactant operate by clearly different mechanisms. The steroids stimulate (via the fibroblast-pneumonocyte factor) production of surfactant phospholipids by alveolar type II cells, enhance the expression of surfactant-associated proteins, reduce microvascular permeability, and accelerate overall structural maturation of the lungs. However, the increment in pool size of surfactant resulting from antenatal treatment with corticosteroids is trivial relative to the dose of exogenous surfactant required for successful prophylaxis at birth. Data from animal experiments indicate that antenatal corticosteroids and postnatal surfactant treatment have synergistic beneficial effects on neonatal lung function, and that these effects can be further potentiated by adding antenatal administration of thyrotrophin releasing hormone (TRH). Promising results have been obtained in recent clinical trials combining antenatal treatment with corticosteroids and TRH for prevention of RDS.
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Affiliation(s)
- B Robertson
- Research Unit for Experimental Perinatal Pathology, St. Göran's Hospital, Stockholm, Sweden
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Jobe AH, Mitchell BR, Gunkel JH. Beneficial effects of the combined use of prenatal corticosteroids and postnatal surfactant on preterm infants. Am J Obstet Gynecol 1993; 168:508-13. [PMID: 8438919 DOI: 10.1016/0002-9378(93)90483-y] [Citation(s) in RCA: 170] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Our objective was to test the hypothesis that prenatal maternal corticosteroids would improve the subsequent response of infants to surfactant treatments. STUDY DESIGN We used the data bases of two recently published large multicenter trials of multidose surfactant treatments to retrospectively evaluate the possible interactions between maternal corticosteroids and randomized surfactant treatments on short-term ventilatory effects, complications of respiratory distress syndrome and prematurity, and 28-day death rates. RESULTS The combined use of corticosteroids and surfactant significantly decreased overall death and death caused by respiratory distress syndrome relative to either treatment alone. Ventilatory variables at 72 hours were improved in those infants receiving both treatments, and other major complications of prematurity also tended to have decreased incidences. CONCLUSION The combined use of prenatal corticosteroids, when indicated, and postnatal surfactant improves neonatal outcome.
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Affiliation(s)
- A H Jobe
- Division of Perinatal Research, Harbor-University of California, Los Angeles Medical Center, Torrance 90509
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Fiascone JM, Hu LM, Vreeland PN. Terbutaline does not improve lung function in preterm rabbits. Am J Obstet Gynecol 1992; 167:847-53. [PMID: 1530049 DOI: 10.1016/s0002-9378(11)91600-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE We used the premature rabbit model of surfactant deficiency to test the hypothesis that perinatal administration of terbutaline would lead to increased secretion of surfactant into the alveolar space and increase lung compliance during mechanical ventilation. STUDY DESIGN Fetuses underwent delivery at a gestational age of 28 days (term 31 days) followed by mechanical ventilation. Fetuses were subdivided into four treatment protocols: control, fetuses given terbutaline at birth, fetuses of mothers given terbutaline 1 hour before delivery, and fetuses of mothers given terbutaline intramuscularly 12 hours before delivery. Dynamic compliance was determined. After this, alveolar lavage fluid was obtained for phosphatidylcholine content determination. Some fetuses were killed at birth and their alveolar lavage phosphatidylcholine was determined. RESULTS Among the fetuses undergoing mechanical ventilation, perinatal terbutaline exposure did not alter either dynamic compliance or alveolar lavage phosphatidylcholine. Mechanical ventilation was associated with large increases in alveolar lavage phosphatidylcholine content. CONCLUSION Perinatal beta-adrenergic agonist exposure does not alter in vivo lung function following preterm delivery.
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Seidner S, Rider E, Jobe A, Yamada T, Ikegami M. Effects of antenatal thyrotropin-releasing hormone, antenatal corticosteroids, and postnatal ventilation on surfactant mobilization in premature rabbits. Am J Obstet Gynecol 1992; 166:1551-9. [PMID: 1595812 DOI: 10.1016/0002-9378(92)91633-l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE The effects of antenatal hormones on postnatal surfactant mobilization were evaluated in preterm rabbits. STUDY DESIGN Pregnant rabbits were treated with vehicle, betamethasone, or thyrotropin-releasing hormone for 2 days before cesarean section at 29 days' gestation (term 31 days). Newborns were mechanically ventilated or allowed to spontaneously breathe, and groups were compared by analysis of variance. RESULTS Neither antenatal corticosteroids nor thyrotropin-releasing hormone increased radiolabeled precursor incorporation, alveolar wash or total lung saturated phosphatidylcholine pools, lung clearance of radiolabeled rabbit surfactant, or estimated net secretion of saturated phosphatidylcholine. However, saturated phosphatidylcholine pools in alveolar wash increased 2.7-fold during the first 24 hours in spontaneously breathing rabbits versus 2.1-fold in mechanically ventilated thyrotropin-releasing hormone-treated and control rabbits (p less than 0.05). In addition, estimated net secretion of precursor-derived saturated phosphatidylcholine was 50% higher after 24 hours in spontaneously breathing rabbits. CONCLUSION Mechanical ventilation may have hindered the mobilization of surfactant saturated phosphatidylcholine pools to the alveolar space after birth in preterm rabbits, but maternal hormonal therapies did not appear to influence this adaptive process or change surfactant metabolism.
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Affiliation(s)
- S Seidner
- Department of Pediatrics, Harbor-University of California, Los Angeles Medical Center, Torrance
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Abstract
Surfactant deficiency has come to be understood as equivalent clinically to lung immaturity, except in situations of extreme prematurity or lung hypoplasia. Thus, surfactant deficiency and the diagnosis respiratory distress syndrome (RDS) have been applied quite uniformly to preterm infants with respiratory distress who have no other identifiable problems. While the diagnosis can be made more specific by assay of surfactant phospholipid composition (12), such measurements are seldom made in clinical practice. Perinatal discussions of the premature with respiratory distress also have been focused toward surfactant by the availability of multiple tests of “lung maturation” based on the assay of surfactant components in amniotic fluid (19). While surfactant is necessary for normal lung function, adequate surfactant is not sufficient to assure normal gas exchange in the preterm. There are no simple ways to separate surfactant deficiency states clearly from other aspects of lung development, such as airway development, alveolarization, and the development of the pulmonary vasculature in the preterm infant. The anatomic data of Hislop et al. (13) and Langston et al. (22) indicate a considerable variability in the number of alveoli in the preterm infant at each gestational age, resulting in large differences in potential gas exchange surfaces in different infants. Airway development also differs between infants of comparable gestational ages, as is evident clinically by susceptibility to the development of pulmonary interstitial emphysema. Assuming that surfactant treatments for RDS fully correct the surfactant deficiency, a realistic expectation based on animal studies (16), surfactant treatments should be useful in the near future to eliminate the surfactant deficiency component of lung immaturity syndromes. Any residual lung disease can then be better characterized.
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Affiliation(s)
- A H Jobe
- Harbor-UCLA Medical Center, Torrance
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16
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Fiascone JM, Mercurio MR, Lima DM, Jacobs HC. Corticosteroids and intratracheal surfactant both alter the distribution between the airways and lung tissue of intratracheally administered radiolabeled phosphatidylcholine in the preterm rabbit. Exp Lung Res 1990; 16:311-21. [PMID: 2394199 DOI: 10.3109/01902149009108847] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Developmental differences exist regarding quantitative aspects of surfactant phosphatidylcholine clearance from the alveolar space and its subsequent reutilization. We wished to further extend observations of this nature to prematurely delivered rabbits undergoing mechanical ventilation. In addition we tested the hypothesis that prenatal corticosteroid exposure and/or intratracheal surfactant at birth would produce alterations in the lung's clearance of phosphatidylcholine from the airways. Pregnant does were injected with either Ringer's lactate or betamethasone on days 25 and 26 of gestation. Fetuses were delivered at 27 days and given by intratracheal injection either surfactant or one-half strength Ringer's lactate, both of which were trace labeled with [3H]phosphatidylcholine. Fetuses then underwent mechanical ventilation for periods of time ranging from 10 to 120 min. Following ventilation, alveolar lavage and lung tissue were examined to determine the distribution of [3H]phosphatidylcholine between these two compartments. Antenatal corticosteroid exposure was associated with decreased recovery of the radiolabel from the alveolar space and increased recovery of the label from the lung tissue in comparison to control fetuses. Intratracheal surfactant was associated with persistence of the radiolabel within the alveolar space. Therapy with both of these modalities produced a radiolabel distribution that resembled that seen in fetuses receiving intratracheal surfactant alone.
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Affiliation(s)
- J M Fiascone
- Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut
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Farrell EE, Silver RK, Kimberlin LV, Wolf ES, Dusik JM. Impact of antenatal dexamethasone administration on respiratory distress syndrome in surfactant-treated infants. Am J Obstet Gynecol 1989; 161:628-33. [PMID: 2675599 DOI: 10.1016/0002-9378(89)90367-0] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Neonatal lung disease is primarily responsible for the perinatal morbidity and mortality associated with preterm birth. Recently exogenous surfactant replacement therapy has been used to prevent or treat respiratory distress syndrome. As part of a multicenter, preventive trial between February 1986 and December 1988 using calf-lung surfactant extract, we treated 147 infants with single dose calf-lung surfactant extract. We analyzed this experience to evaluate the possibility that antenatal steroids may be additive (with calf-lung surfactant extract) in reducing both the incidence and severity of respiratory distress syndrome. Although a reduction in the incidence of respiratory distress syndrome was observed among the 33 neonates exposed to antenatal dexamethasone when compared with the 114 infants given calf-lung surfactant extract alone, the difference was not significant (37.7% vs. 24.2% p = 0.15). However, comparison of neonatal subsets previously shown to benefit most from steroid use revealed an additive effect between calf-lung surfactant extract and dexamethasone in reducing both the incidence and severity of respiratory distress syndrome. Of the 99 singleton pregnancies, only 2 of 16 infants treated with calf-lung surfactant extract and dexamethasone developed respiratory distress syndrome, compared with the 33 of 83 calf-lung surfactant extract cases (p less than 0.05). A similar reduction was observed in infants between 28 and 32 weeks' gestation (calf-lung surfactant extract, 21 of 79 vs. calf-lung surfactant extract and dexamethasone, 0 of 24; p less than 0.05). A reduction in disease severity was observed in male offspring (moderate or severe respiratory distress syndrome only; 22 of 63 vs. 2 of 22; p less than 0.05). Potential confounding variables (e.g., gestational age at birth, birth weight, exposure to tocolytics before delivery, fetal pH at birth) were similar in all comparisons. We conclude that an additive effect between dexamethasone and calf-lung surfactant extract is observed in selected cases. It may therefore be appropriate to maximize antenatal steroid use in centers where exogenous surfactant is available.
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Affiliation(s)
- E E Farrell
- Division of Neonatology, Evanston Hospital, IL 60201
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