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Biomedical subjects

M Hallman

Publications and source records attributed to M Hallman.

At least 145 records · Page 8Linked to original sources
PubMed1987

Inositol supplementation in respiratory distress syndrome: relationship between serum concentration, renal excretion, and lung effluent phospholipids.

Inositol or placebo was given to 48 small preterm infants with respiratory distress syndrome (mean birth weight 1365 g, gestational age 30.1 weeks) between 48 hours and 10 days of age. The dose of inositol, 40 mg/kg every 6 hours, was at least as high as amounts received in full preterm human milk feedings. Serum inositol concentration increased between days 2 and 3 from a mean of 566 mumol/L to 823 mumol/L in the infants given supplement and fell from 451 mumol/L to 292 mumol/L in the controls. On day 16, serum inositol values remained higher in the infants given supplement than in those given placebo (mean 334 mumol/L vs 146 mumol/L, P = 0.014). The infants who developed bronchopulmonary dysplasia had significantly higher renal inositol clearance, lower inositol intake, and lower serum inositol concentrations. Inositol supplementation increased the saturated phosphatidylcholine/sphingomyelin ratio in tracheal aspirates. According to these results, supplementation with inositol in preterm infants leads to a rise in serum inositol concentration and improvement in the surfactant phospholipids. Inositol deserves further study as a dietary supplement for immature preterm infants who do not receive full human milk feeds.

Double-Blind Method↗
PubMed1987

Natural surfactant substitution in respiratory distress syndrome.

Natural surfactants consist of unique proteins and lipids. Their effectiveness in improving subnormal lung function in surfactant deficiency should be established prior to any clinical trials. Rigorous tests are required to document batch to batch variability in surface activity and to exclude toxic contaminants. Up to this date randomized clinical trials in small preterm infants have demonstrated a striking improvement in lung function, and a decrease in incidence of acute complications (pneumothorax, interstitial emphysema). Administration of human surfactant at birth or in severe RDS decreased deaths and incidence of bronchopulmonary dysplasia. Although homologous surfactant may not be more advantageous than the heterologous one in terms of its acute beneficial effects on lung function, the safety and efficacy of animal surfactant in improving the outcome remains to be established. Human surfactant may serve as a model for unlimited natural surfactant produced by gene technology. The pharmacodynamics aspects of surfactant substitution, the indications of exogenous surfactant, and the management of the patients undergoing surfactant substitution remain to be studied. Exogenous surfactant offers a potential to treat or prevent severe respiratory failure in infants, children and adults.

Animals↗
PubMed1987

Respiratory failure following anti-lung serum: study on mechanisms associated with surfactant system damage.

Within 2 minutes intravenous anti-lung serum (ALS) into guinea pig induces a respiratory failure that is fatal within 30 min. The relationship between surfactant, alveolar-capillary permeability and respiratory failure was studied. Within two minutes ALS induced a leak in the alveolar-capillary barrier. Within 30 minutes 28.3% (controls, given normal rabbit serum: 0.7%) of iv 131I-albumin, and 0.5% (controls 0.02%) of iv surfactant phospholipid tracer were recovered in bronchoalveolar lavage. Furthermore, 57% (controls 32%) of the endotracheally administered surfactant phospholipid became associated with lung tissue and only less than 0.5% left the lung. The distribution of proteins and phospholipids between the in vivo small volume bronchoalveolar lavages and the ex vivo bronchoalveolar lavages were dissimilar: 84% (controls 20%) of intravenously injected, lavageable 131I-albumin and 23% (controls 18%) of total lavageable phospholipid were recovered in the in vivo small volume bronchoalveolar lavages. ALS also decreased lavageable surfactant phospholipid by 41%. After ALS the minimum surface tension increased. The supernatant of the lavage increased the minimum surface tension of normal surfactant. In addition, the sediment fraction of the lavage had slow surface adsorption, and a marked reduction in 35,000 and 10,000 MW peptides. Exogenous surfactant ameliorated the ALS-induced respiratory failure. We propose that inhibition, altered intrapulmonary distribution, and dissociation of protein and phospholipid components of surfactant are important in early pathogenesis of acute respiratory failure.

Animals↗
PubMed1987

Surfactant abnormality after endotoxin-induced lung injury in guinea-pigs.

Endotoxin (30 mg/kg) or saline was given endotracheally to guinea-pigs in order to investigate surfactant function in respiratory failure. Six hours later, bronchoalveolar lavage was performed. The lavage was analyzed for protein, phospholipids and surface activity, and fractioned into the phospholipid-rich sediment and the phospholipid-poor supernatant. The latter fraction was analyzed for surfactant inhibitor activity. After endotoxin, PaO2 and static lung-thorax compliance decreased. The lavage from endotoxin-treated animals revealed a 180% increase in protein, a 52 67% decrease in surfactant phospholipids, and increased minimum surface tension, as compared to the controls. After endotoxin, the supernatant contained a 58% higher activity of surfactant inhibitor, and the sediment had slower surface adsorption than after saline. We propose that abnormal surfactant function is important in the pathogenesis of respiratory failure in high-permeability pulmonary edema.

Animals↗
PubMed1987

Comparison of four surfactants: in vitro surface properties and responses of preterm lambs to treatment at birth.

Natural sheep surfactant, rabbit surfactant, human surfactant, and surfactant TA were compared for in vitro surface properties and for responses of preterm lambs to treatment. Equivalent amounts of sheep, rabbit, and human surfactants were needed to lower the surface tension to less than 10 dynes/cm, whereas four times less surfactant TA similarly lowered the surface tension. Surface-spreading rates were similar for the surfactants. The surface adsorption of the batch of human surfactant tested was much slower than was adsorption of the other surfactants. Ventilation was significantly improved in all surfactant-treated lambs relative to the control lambs, indicating the general efficacy of the surfactant treatments. Overall, surfactant TA had the best in vitro characteristics, yet the preterm lambs treated at birth with surfactant TA had lower PO2 values and higher ventilatory requirements than did the sheep surfactant-treated lambs. The in vivo responses to rabbit surfactant were intermediate between the responses to sheep surfactant and to surfactant TA. Human surfactant resulted in the least effective clinical response. More of the phosphatidylcholine associated with human surfactant and surfactant TA was lost from the alveoli and lung tissue after four hours of ventilation than was lost from sheep or rabbit surfactant-treated lambs. More intravascular radiolabeled albumin leaked into the alveoli of the surfactant TA-treated lambs than sheep or rabbit surfactant-treated lambs. The four surfactants also had different sensitivities to the effects on minimum surface tensions of the soluble proteins present in alveolar washes. The study demonstrates that the range of clinical responses was not predictable based on the in vitro surface properties that we measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Prophylactic treatment of very premature infants with human surfactant.

We undertook a randomized, controlled trial to determine whether human surfactant administered endotracheally at birth to very premature infants (gestational age, 24 to 29 weeks) would prevent the respiratory distress syndrome or reduce its severity. Thirty-one treated infants (birth weight, 938 +/- 286 g) were compared in a blinded fashion with 29 control infants (birth weight, 964 +/- 174 g). The lecithin/sphingomyelin ratio was less than 2 in all infants, and phosphatidylglycerol was not present in amniotic fluid or tracheal fluids at birth, indicating a deficiency of surfactant in the lungs. The principal dependent variables were neonatal death, the incidence of bronchopulmonary dysplasia, and the infant's requirement for respiratory support (and its complications). The surfactant-treated group had significantly fewer deaths than the control group (16 percent vs. 52 percent, P less than 0.001), fewer cases of bronchopulmonary dysplasia (16 percent vs. 31 percent), and significantly fewer cases of pulmonary interstitial emphysema (P less than 0.001) and pneumothorax (P less than 0.02). Prophylactic treatment with human surfactant also substantially reduced the period of neonatal intensive care. We conclude that treatment with human surfactant offers promise for improving the survival of very premature infants with a surfactant deficiency and for reducing the pulmonary sequelae of the respiratory distress syndrome.

Amniotic Fluid↗
PubMed1986

Presence of apocrine epithelial antigen (AEA) in type II pneumocytes and in hyaline membranes of neonatal RDS.

We have investigated the distribution of an apocrine membrane antigen (AEA) in pulmonary tissue using a rabbit antiserum raised against fat globule glycoproteins isolated from human milk. In indirect immunostaining (PAP, IF) of sections from normal lung tissue, the membranes facing the alveolar lumen of cells corresponding to the type II pneumocytes in the alveolar walls were decorated. The selective distribution of AEA to the membranes of type II pneumocytes was confirmed in double immunostaining by identification of these cells with rat antibodies against surfactant apoprotein. In fetal lung tissue, the AEA antigen was detected by the 9th week of gestation. In lung samples from newborns which had died of respiratory distress syndrome (RDS) the intra-alveolar hyaline membranes stained for the AEA antigen. SDS-PAGE of the immunoprecipitate obtained with anti-AEA serum from radiolabelled glycoprotein fraction of normal lung tissue revealed a single band of 79,000 dalton apparent molecular weight. These findings indicate that the AEA constitutes a membrane marker of the type II pneumocytes and might be involved in the secretory process of surfactant. Immunohistological evidence for the presence of AEA in the hyaline membranes of neonatal RDS is also presented.

Antigens↗
PubMed1986

Human surfactant treatment of severe respiratory distress syndrome: pulmonary effluent indicators of lung inflammation.

Pulmonary effluent from infants who received exogenous human surfactant for severe respiratory distress syndrome was evaluated for inflammatory changes previously identified with lung injury during the first 2 weeks after birth. The number of pulmonary effluent inflammatory cells was higher only on day 1 in infants given surfactant. No other evidence of enhanced inflammation was detected in cytologic assessment of tracheal secretions. The classical pathway of complement was not activated in infants given surfactant or in control infants 2 weeks after birth. Albumin content of airway secretions was higher on the first day but not significantly altered on subsequent days. Human surfactant treatment was not associated with increased proteolytic activity, measured as neutrophilic elastase per milligram of albumin in lung effluent, but was associated with significantly higher alpha 1-proteinase inhibitor levels than in control infants from days 2 to 7 after birth. These findings provide evidence that exogenous human surfactant instilled into the lungs of preterm infants with severe respiratory distress syndrome is not associated with enhanced lung inflammation, compared with conventional mechanical ventilation alone. These data support additional clinical trials using human surfactant.

Albumins↗
PubMed1986

Respiratory distress syndrome and inositol supplementation in preterm infants.

We report a randomised double blind trial of myo-inositol (inositol) supplementation for 10 days in 74 preterm infants with a birth weight less than 2000 g (mean gestational age 29.5 weeks and mean birth weight 1266 g). All infants required artificial ventilation for treatment of respiratory distress syndrome. Inositol (120-160 mg/kg/day) was administered by the ingastric or intravenous route. The 37 infants who received inositol supplementation required less mechanical ventilation during days 4-10, had less failures of indomethacin to close ductus arteriosus, and had less deaths or bronchopulmonary dysplasia, or both, than the infants treated with placebo. There were no detectable adverse effects. These preliminary results suggest that inositol is an important nutrient in immature preterm infants.

Clinical Trials as Topic↗
PubMed1986

Reconstitution of surfactant activity using purified human apoprotein and phospholipids measured in vitro and in vivo.

The major apoprotein of human lung surfactant was isolated from amniotic fluid obtained at term gestation. It was found to be a disulfide-linked oligomer composed of polypeptide chains of 35,000 daltons. The monomeric unit was shown to be a glycoprotein, and treatment with peptide: N-glycosidase F resulted in a decrease in molecular weight to 31,000 daltons. The isolated apoprotein could be recombined in the presence of Ca++ with the phospholipids dipalmitoylphosphatidylcholine and phosphatidylglycerol (3:1) at a weight ratio of 1:100. The surface tension (gamma min) measured on a pulsating bubble formed in 4 mg/ml of phospholipids was reduced from 32.3 +/- 2.0 dyn X cm-1 to 18.0 +/- 0.6 dyn X cm-1 after 15 s when 1% apoprotein was present. Reduction of disulfide bonds and deglycosylation of the apoprotein did not alter its ability to lower gamma min. Fetal rabbits of 27 days gestation had instilled intratracheally at delivery, saline, phospholipids, phospholipids plus apoprotein, or natural human surfactant. The latter 2 resulted in increased lung compliance and striking improvement in homogeneous alveolar expansion when the lungs were expanded to 10 cm H2O pressure, fixed, and viewed histologically. This effect was also shown to be independent of the disulfide-dependent oligomeric structure of the apoprotein or its state of glycosylation. The surfactant produced by recombination of the phospholipids with the isolated apoprotein was, therefore, shown to be biophysically active both in vitro and in vivo. These data suggest that apoprotein can be recombined with phospholipids to produce a biologically active surfactant for use in clinical trials of human surfactant replacement.

Animals↗
PubMed1986

Perinatal development of myoinositol uptake into lung cells: surfactant phosphatidylglycerol and phosphatidylinositol synthesis in the rabbit.

It has been proposed that the high serum myoinositol promotes fetal growth and affects development of lung surfactant. However, it is unclear how the extracellular myoinositol becomes available in specific cells and whether there are developmental differences in myoinositol uptake. In the present study the mechanisms and perinatal development of intracellular myoinositol uptake into rabbit lung cells were investigated. Lung slices, lung explants, and type II alveolar cells were used. Evidence of saturable, sodium- and energy-dependent, and of non-saturable, sodium- and energy-independent myoinositol uptake was found. The nonsaturable uptake decreased by 67% during spontaneous maturation, as studied in lung slices. Beta-methasone (0.2 mg/kg days 26.3 and 27.3, to the doe) decreased by 65% the nonsaturable myoinositol uptake in 28-day-old fetuses. However, the saturable uptake revealed only small changes during perinatal development. The effect of extracellular myoinositol on surfactant phospholipid synthesis was evaluated in lung explants from 28-day-old fetuses, cultured for 2 days. In the presence of 10(-6) M dexamethasone the concentration of extracellular myoinositol, required for half-maximal inhibition of surfactant phosphatidylglycerol incorporation was higher than in explants grown without the hormone (approximately 0.4 versus 0.2 mM). However, in the microsomal fraction the phosphatidylglycerol incorporation was always inhibited by as low as 4 microM myoinositol. Myoinositol was taken up by isolated type II cells preferably by nonsaturable mechanism. The phosphatidylglycerol incorporation was less sensitive to extracellular myoinositol in adult than in fetal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Effect of surfactant substitution on lung effluent phospholipids in respiratory distress syndrome: evaluation of surfactant phospholipid turnover, pool size, and the relationship to severity of respiratory failure.

The turnover and pool size of surfactant has been studied in animals, but there is little similar information in humans. In the present investigation lung effluent phospholipids were studied in 29 small preterm infants with severe RDS. Thirteen were treated with mechanical ventilation, and 16 additionally received natural human surfactant. The first dose (60 mg surfactant/kg body wt) was given between 2 and 10 h of age, and the surfactant was given again if there was an insufficient response. Together 260 aspirates, recovered during routine suctioning of the airways, were analyzed for phospholipids. Phosphatidylglycerol, present only in exogenous surfactant, was used as a specific marker to estimate the apparent pool size and the half-life of surfactant phospholipid. In addition, the saturated phosphatidylcholine/sphingomyelin ratios were correlated with the ventilatory index (mean airway pressure X fractional inspiratory oxygen/arterial oxygen tension). There was a linear correlation between the ventilatory index and the saturated phosphatidylcholine/sphingomyelin (r approximately -0.70) but no consistent correlation between the ventilatory index and the amount of phospholipids in the aspirate. The saturated phosphatidylcholine/sphingomyelin ratio increased during the surfactant-induced remission of respiratory failure, decreased during the recovery. The control infants tended to have lower saturated phosphatidylcholine/sphingomyelin ratios during the first week than the surfactant-treated infants.(ABSTRACT TRUNCATED AT 250 WORDS)

Half-Life↗
PubMed1986

Surfactant-anti-surfactant immune complexes in infants with respiratory distress syndrome.

The authors sought to determine whether treatment of respiratory distress syndrome (RDS) with human surfactant resulted in the formation of detectable circulating immune complexes. Preterm infants with severe RDS were divided into two groups: one group received human surfactant by intratracheal instillation and the other group did not. Both groups received ventilatory management involving intermittent mandatory ventilation. Plasma samples were drawn from these babies prior to treatment and at intervals thereafter. The authors developed an ELISA assay specific for surfactant-anti-surfactant immune complexes and analyzed the plasma samples for such immune complexes. Complement levels were also measured. They found that with time plasma from RDS infants in both groups showed evidence of surfactant-anti-surfactant immune complex formation. The concentrations of immune complexes generally peaked within the first week of life and then appeared to diminish over 1-4 weeks after birth in RDS infants. There was no evidence at any time in either group of immune-complex-mediated injury or of decreased serum complement levels. It is concluded that circulating immune complexes between surfactant and antibodies to surfactant are probably found in most neonates with respiratory distress syndrome, that they do not produce pulmonary damage detectable by clinical and serologic means, and that treatment of neonatal RDS with human surfactant similarly does not produce lung injury as determined with these techniques.

Antibody Specificity↗
PubMed1985

Role of myoinositol in regulation of surfactant phospholipids in the newborn.

According to animal studies myoinositol decreases surfactant phosphatidylglycerol and increases phosphatidylinositol. In the present study lung effluent phospholipids and serum myoinositol were analyzed in respiratory distress syndrome (RDS, 19 cases), in other lung disease (6 cases) and in 22 newborn with no lung disease. In addition, myoinositol was studied in amniotic fluid and in serum from umbilical vessels and from maternal vein (15 healthy newborn). There was a significant correlation between the fetal and amniotic fluid levels of myoinositol, but no detectable correlation between fetal and maternal myoinositol. Serum myoinositol was higher in preterm than in term newborns. In healthy newborns there was a negative correlation between lung effluent phosphatidylglycerol (expressed as percent of the phospholipids) and serum myoinositol (r = -0.968), and a positive linear correlation between myoinositol and lung effluent phosphatidylinositol (r = 0.849). In RDS at birth, undetectable phosphatidylglycerol corresponded with high serum myoinositol. During the first 5 neonatal days serum myoinositol either (1) decreased and phosphatidylglycerol appeared, (2) remained high and phosphatidylglycerol correspondingly low in some small preterm infants, or (3) decreased but phosphatidylglycerol did not expectedly increase and disaturated lecithin/sphingomyelin ratio remained low in other small preterm babies. We propose that a premature decrease in serum myoinositol among small preterm infants with RDS is not beneficial, since myoinositol may promote hormone-induced lung maturation and healing of lung damage.

Humans↗
PubMed1985

Exogenous human surfactant for treatment of severe respiratory distress syndrome: a randomized prospective clinical trial.

We performed a randomized, prospective clinical trial comparing intratracheal administration of human surfactant with conventional treatment with intermittent mandatory mechanical ventilation alone for treatment of severe respiratory distress syndrome in preterm infants of less than 30 weeks gestation. Twenty-two infants (mean gestational age 27.0 weeks, mean birth weight 987 gm) were given surfactant, and 23 infants (mean gestational age 27.2 week, mean birth weight 1055 gm) received intermittent mandatory ventilation. Infants given surfactant required less FiO2 during the first week, had lower mean airway pressure during the first 48 hours, and had improved ventilatory index and a/A PO2 ratio. Death or the occurrence of bronchopulmonary dysplasia was significantly less among infants given surfactant (P = 0.019). Pneumothorax, pulmonary interstitial emphysema, and need for FiO2 greater than or equal to 0.3 for greater than 30 days was significantly less in the surfactant group. This trial confirms the efficacy of treatment with human surfactant in preterm infants with severe respiratory distress syndrome.

Amniotic Fluid↗
PubMed1985

Respiratory distress syndrome treated with human surfactant: radiographic findings.

Chest radiographs of 18 newborns treated with endotracheal instillation of human surfactant for respiratory distress syndrome (RDS) were compared with those of 18 similar but untreated infants. In the treated infants, severity of RDS significantly improved after surfactant administration. Most treated infants (16/18) exhibited a left-to-right shunt, presumably through a patent ductus arteriosus; similar findings were noted in untreated infants (17/18). Complications of respiratory assistance in the treated infants included transient pulmonary interstitial emphysema (n = 1), pneumothorax (n = 1), and mild (n = 4) to moderate (n = 2) bronchopulmonary dysplasia; the incidences of these complications did not exceed those in untreated infants. In three treated infants, a transient interstitial lung disease developed 3-4 days after surfactant administration.

Ductus Arteriosus, Patent↗