Increased plasma immunoreactive 6-keto-prostaglandin F1 alpha levels in newborns with idiopathic respiratory distress syndrome

An active peptide from yak inhibits hypoxia-induced lung injury via suppressing VEGF/MAPK/inflammatory signaling

Pulmonary vascular remodeling and inflammation play an important role in the hypoxic-induced lung diseases. Our previous investigations showed that peptide from yak milk residues could alleviate inflammation. In this study, our results suggest that peptide (LV) from yak milk residues peptide had protective effect of lung in the animal models of hypoxic-induced lung injury. LV Gavage could improve pulmonary vascular remodeling in the lung tissues of hypoxic mice. A comprehensive analysis of metabolomics and transcriptomics revealed that 5-KETE, 8,9-EET, and 6-keto-prostaglandin F1a might be potential targets to prevent lung injury in the hypoxic mice. These metabolites can be regulated by MAPK/VEGF and inflammatory pathways. Our data indicated that LV treatment could inhibit apoptosis and inflammation via Nrf2/NF-κB/MAPK/PHD-2 pathway and protected hypoxic-induced lung epithelial cells injury. Taken together, our results suggest that LV provides a novel therapeutic clue for the prevention of hypoxia-induced lung injury and inflammation-related lung diseases.

Acute changes in vasoactive lipid mediators in experimental hyaline membrane disease

Endothelial release of the arachidonate derivative PGI2 may be increased in response to cyclic lung stretching. We therefore sought to determine if the stable metabolite of PGI2, 6-keto-PGF1 alpha, would be found in increased quantities in primates ventilated with conventional mechanical ventilation (CMV) compared to treatment with high frequency oscillatory ventilation (HFOV). We also sought to determine if other membrane-derived vasoactive substances such as LTC4, PAF and TXB2 would be elevated in plasma and lung tissue of animals developing hyaline membrane disease (HMD) and if the levels would correlate with the severity of the respiratory distress. Twenty prematurely delivered monkeys were treated with either CMV or HFOV from the first breath after Cesarean delivery until sacrifice at 6 h of age. We found a significant increase from birth to 5 min and from 5 min to 5 h in 6-keto-PGF1 alpha, and a significant increase from 5 min to 5 h in TXB2. We found a significant decline from cord blood to 5 min of LTC4, without further change by 5 h. PAF was present in all plasma samples but showed no upward or downward trend. There was no difference in the 5-h plasma level or in the lung homogenate level of any of the lipid mediators between the two types of assisted ventilation. There was no correlation between any lipid mediator level and severity of the HMD, as measured by gas exchange, radiographic or histologic criteria, when assessed by each ventilator group alone or with both groups combined. We conclude that the immediate postnatal increases in TXB2 and PGI2 and decrease in LTC4 are not altered substantially by use of HFOV.

Doppler assessment of pulmonary artery pressure and extrapulmonary shunting in the acute phase of hyaline membrane disease

The natural history of pulmonary artery pressure and extrapulmonary shunting in acute hyaline membrane disease was studied by serial Doppler echocardiography in 57 preterm infants, 38 with, and 19 without, hyaline membrane disease. Pulmonary artery pressure was assessed non-invasively by its inverse relationship with the ratio of pulmonary artery Doppler time to peak velocity: right ventricular ejection time. The mean ratio was significantly lower in the infants with hyaline membrane disease. The mean ratio for each infant with hyaline membrane disease varied widely and did not correlate with criteria of maturity or severity of disease. Individual ratios correlated with arterial pH. Between 60-80 hours after birth, 14 of 18 infants with hyaline membrane disease (78%) and one of 19 without (5%) had patent ductus arteriosus. Left to right and bidirectional shunting at ductal and atrial level were common; pure right to left shunting was uncommon. The mean ratio seen with bidirectional shunting was significantly lower than that seen with left to right shunting. Ratios and patterns of extra pulmonary shunting were similar when the fractional inspired oxygen (FIO2) was greater than 0.9 compared with when it was less than 0.9. Pulmonary artery pressure is high during the acute phase of hyaline membrane disease but varies widely among infants. A few infants have extrapulmonary right to left shunting, and these infants are difficult to detect clinically.

Oleic acid lung injury increases plasma prostaglandin levels

To determine whether lung injury causes increased plasma prostaglandin (PG) levels, 35 rabbits received oleic acid and 35 served as controls. Half of each group also received 4 ml/kg of Intralipid over one hour and at least five in each subgroup received indomethacin 7.5 mg/kg. Arterial and venous plasma concentrations of PGE2, 6-keto-PGF1 alpha, and PGF2 alpha-M were measured. Venous PGE2 was significantly higher in the oleic acid-injured than in the normal lung group, 1560 +/- 270 (Mean +/- SEM) versus 880 +/- 140 pg/ml (p less than .05). Plasma levels were reduced by 50% with indomethacin, but PGE2 levels remained significantly higher than in the normal lung group, 850 +/- 180 versus 480 +/- 60 for arterial (p less than .05) and 820 +/- 140 versus 480 +/- 80 for venous (p less than .05), respectively. PGF2 alpha-M levels were significantly higher in the lung injury group, 240 +/- 50 versus 50 +/- 40 pg/ml for arterial (p less than .05) and 220 +/- 50 versus 95 +/- 40 for venous (p less than .05), respectively. These lung injury-related increases in PGE2 and PGF2 alpha-M appear related both to increased pulmonary production and to decreased pulmonary clearance. With Intralipid infusion, however, arterial PGE2 increased by 500 +/- 260 pg/ml compared to baseline (p less than .05) with no change in venous PGE2, indicating in this instance that the increase in arterial PGE2 levels is related to increased pulmonary production.

Elevated levels of immunoreactive prostacyclin metabolite in babies who develop intraventricular haemorrhage

Measurement of 6-ketoprostaglandin F1-alpha by radioimmunoassay was made during the first three days of life in a group of 48 preterm neonates at risk of intraventricular haemorrhage. The babies who developed haemorrhage had significantly higher levels than those who did not, and failed to show the falling levels seen over the first three days of life in the nonhaemorrhage group. It is suggested that high levels of prostacyclin in low birthweight babies may be one factor which contributes to the alterations of cerebral blood flow and capillary bleeding time which predispose to intraventricular haemorrhage.

Endogenous dilator prostaglandins in congenital heart disease

Maintaining patency of the ductus arteriosus pending surgical intervention can be critical to the survival of the neonate with ductal dependent congenital heart disease. Spontaneously delayed ductal closure has been observed clinically and experimentally in newborns with critical pulmonic stenosis. Infants with ductal dependent congenital heart lesions were therefore studied to ascertain whether there was an endogenous increase in dilator prostaglandins prolonging ductal patency. Six neonates with cyanotic lesions (group 1) and six with left ventricular obstructive lesions (group 2) were studied. Circulating PGE2 was not increased in either group. The levels of plasma 6 keto PGF1 alpha, a stable hydrolysis product of prostacyclin, were found to be elevated, but only in the cyanotic group (3143 +/- 1844 vs 404 +/- 250 pg/ml; p less than 0.05; normal less than 500 pg/ml). As expected, PaO2's were also different (36 +/- 15 vs 72 +/- 34 mmHg; p less than 0.05). It is speculated, therefore, that increased synthesis and/or release of prostacyclin, possibly mediated by the hypoxia of the cyanotic ductal dependent lesion, contributes to persistent patency of the ductus arteriosus.

Ethamsylate reduces immunoreactive prostacyclin metabolite in low birthweight infants with respiratory distress syndrome

Measurement of 6 ketoprostaglandin F1 alpha was made by radioimmunoassay during the first 3 days of life in 33 infants with respiratory distress syndrome who were subjects in a double blind controlled trial of ethamsylate for the prevention of intraventricular haemorrhage. Levels of 6-ketoprostaglandin F1 alpha were significantly lower on the first and second days of life in babies receiving ethamsylate. There was a reduction in the incidence of intraventricular haemorrhage in the treated group. High levels of prostacyclin metabolite are found in babies who develop haemorrhage, and reduction of prostacyclin synthetase activity may be the mode of action of this drug in vivo.

Fetal and neonatal prostacyclin and thromboxane in relation to mode of delivery

To study whether prostacyclin and thromboxane A2 might play a role in neonatal adaption pieces of the umbilical arteries of infants born vaginally (n = 18) or by elective caesarean section (n = 11) were superfused in vitro and the release of 6-keto-PGF1a (hydration product of prostacyclin) and thromboxane B2 (metabolite of thromboxane A2) measured by radioimmunoassay. In addition, the capacity of fetal platelets to produce thromboxane A2 and the neonatal urinary concentrations of 6-keto-PGF1a were measured. Infants born by caesarean section had lower diastolic blood pressure, higher heart rate, and smaller differences between rectal and skin temperature compared with infants born vaginally during the first two hours of life. The only difference encountered in the prostanoids between the groups was reduced urinary excretion of 6-keto-PGF1a in infants born by caesarean section, whose release of 6-keto-PGF1a by the umbilical artery was positively correlated with heart rate, respiration frequency, and dermal temperature. Thus prostacyclin may be a regulatory determinant, particularly in infants born by caesarean section.

Reduction of immunoreactive prostacyclin metabolite after paralysis in ventilated preterm infants

Levels of the stable metabolite of prostacyclin, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) were measured by radioimmunoassay during the first 48 hours of life in a group of 20 infants ventilated for the respiratory distress syndrome in whom a simultaneous record of respiratory activity was made. 6-Keto-PGF1 alpha was significantly lower when the infants were paralysed (P = 0.0004) than when they were breathing spontaneously. Elimination of the capacity for spontaneous respiration may reduce barotrauma and hence the stimulus for prostacyclin release from the lung.

Plasma 6-keto prostaglandin F1 alpha and thromboxane B2 in sick preterm neonates

To determine if vascular abnormalities in preterm neonates might be related to vasoactive prostaglandins, stable prostacyclin (6-KPGF1 alpha) and thromboxane A2 (T X B2) metabolites in arterial blood were measured at less than or equal to 6 hours after birth and at 24, 48, and 72 hours using a radioimmunoassay. Neonates of less than 32 weeks gestation (N = 26) were diagnosed as having either the idiopathic respiratory distress syndrome (IRDS, N = 15) or pulmonary edema (PE, N = 11), and were also grouped according to the presence or absence of intracranial hemorrhage (ICH, N = 11) or patent ductus arteriosus (PDA, N = 10). Initial plasma 6-KPGF1 alpha was greater in neonates with ICH (0.23 +/- 0.04 ng/ml, mean +/- SE) than without ICH (0.11 +/- 0.04, p less than 0.05). Neonates with both ICH and IRDS (N = 8) had significantly elevated T X B2 at all sampling times compared to neonates with IRDS and no ICH (N = 7). Both T X B2 and 6-KPGF1 alpha increased with time in those with major ICH. Among neonates without ICH, 7 with IRDS had higher initial 6-KPGF1 alpha (0.19 +/- 0.07 ng/ml) and lower T X B2 (0.15 +/- 0.04 ng/ml) than 8 with PE (0.04 +/- 0.01 and 0.37 +/- 0.09 ng/ml, respectively). The initial 6-KPGF1 alpha (0.024 + 0.003 ng/ml), measured in neonates with PE and without PDA or ICH (N = 6), was significantly less than the corresponding value in the other neonates (0.201 +/- 0.036 ng/ml) (N = 20).