Gunnar A. Rau

Evaluation of portal venous gas detected by ultrasound examination for diagnosis of necrotising enterocolitis.

Background: Early diagnosis of necrotising enterocolitis (NEC) is difficult but essential for timely therapy. The diagnostic hallmarks and specific radiological signs for NEC are pneumatosis intestinalis (PI) and portal venous gas (PVG), but PVG in abdominal ultrasound (PVG-US) has been proposed as an effective tool in the diagnosis of NEC as well. Objective: To prospectively assess the value of PVG-US for the diagnosis of NEC. Methods: The study screened 352 neonates for PVG-US (n = 796 routine examinations) and performed 48 additional screenings in 34/352 neonates with suspected (stage I, n = 28) or definite NEC (stage ⩾II, n = 20). Sensitivity and specificity of PVG-US for detection of NEC were computed by using NEC stage ⩾II as the reference standard. Results: PVG-US was only present in cases of suspected or definite NEC. The study observed PVG-US in 4/28 NEC stage I and in 9/20 NEC stage ⩾II episodes corresponding to a 86% specificity and a 45% sensitivity for diagnosis of NEC stage ⩾II. However, 7/20 patients with NEC stage ⩾II showed intraoperative findings other than NEC and another 3/20 infants presented with radiologically unspecific intestinal dilatation. None of these 10 infants had detectable PVG-US. Thus, with application of specific radiological signs the sensitivity of PVG-US for diagnosis of NEC stage ⩾II increased to 90%. Conclusion: Screening for PVG-US is a useful, easy and quick bedside test with a high specificity for NEC. Moreover, these results question the value of the Walsh criteria in the diagnosis of NEC.

Molecular Species Compositions of Lung and Pancreas Phospholipids in the cftr tm1HGU/tm1HGU Cystic Fibrosis Mouse

Fatty acid analysis of phospholipid compositions of lung and pancreas cells from a cystic fibrosis transmembrane regulator (CFTR) negative mouse (cftr−/−)suggested that a decreased concentration of docosahexaenoate (22:6n-3) and increased arachidonate (20:4n-6) may be related to the disease process in cystic fibrosis (CF). Consequently, we have determined compositions of the major phospholipids of lung, pancreas, liver, and plasma from a different mouse model of CF, the cftrtm1HGU/tm1HGU mouse, compared with ZTM:MF-1 control mice. Electrospray ionization mass spectrometry permitted the quantification of all of the individual molecular species of phosphatidylcholine (PtdCho), phosphatidylethanolamine (PtdEtn), phosphatidylglycerol (PtdGly), phosphatidylserine (PtdSer), and phosphatidylinositol (PtdIns). There was no deficiency of 22:6n-3 in any phospholipid class from lung, pancreas, or liver from mice with the cftrtm1HGU/tm1HGU. Instead, the concentration of 20:4n-6 was significantly decreased in plasma PtdCho species and in pancreas and lung species of PtdEtn, PtdSer, and PtdIns. These results demonstrate the variability of membrane phospholipid compositions in different mouse models of CF and suggest that in cftrtm1HGU/tm1HGU mice, the apparent deficiency was of 20:4n-6- rather than of 22:6n-3–containing phospholipid species. They highlight a need for detailed phospholipid molecular species analysis of cells expressing mutant CFTR from children with CF before the therapeutic effects of administering high doses of 22:6n-3–containing oils to children with CF can be fully evaluated.

METABOLISM OF SURFACTANT PHOSPHATIDYLCHOLINE MOLECULAR SPECIES IN cftr tm1HGU tm1HGU MICE COMPARED TO MF-1 MICE

In cftrtm1HGU/tm1HGU mice, an animal model designed to study pathophysiologic alterations due to the CFTR defect found in cystic fibrosis, surfactant phospholipids of bronchoalveolar lavage fluid (BALF)are increased. To study the metabolical basis of such increases, we intraperitoneally injected cftrtm1HGU/tm1HGU mice [methyl-3H]choline and measured [methyl-3In cftr(tmIHGU/m1HGU) mice, an animal model designed to study pathophysiologic alterations due to the CFTR defect found in cysticfibrosis, surfactant phospholipids of bronchoalveolar lavage fluid (BALF) are increased. To study the metabolical basis of such increases, we intraperitoneally injected cft(tm1HGU/tm1HGU) mice [methyl-3H]choline and measured [methyl-3H]choline incorporation into phosphatidylcholine (PC) molecular species of lung tissue and BALF after 1.5 to 24 hours. MF1 and MF1 x cftr(tm1HGU/tm1HGU) hybrid mice served as controls. In tissue [methyl-3H]choline incorporation into total PC was constant for 24 hours and identical in control and cftr(tmIHGU/m1HGU) mice. However, from 7.5 to 24 hours there was a shift of [methyl-3H]choline incorporation from palmitoyloleoyl-PC and palmitoyllinoleoyl-PC towards PC species enriched in surfactant, dipalmitoyl-PC, palmitoylmyristoyl-PC, and palmitoylpalmitoleoyl-PC. The relative and absolute 3H-labels of PC species were identical for cftr(tmIHGU/m1HGU) compared to control mice. In BALF [methyl-3H]choline of total PC increased from 1.5 to 24 hours (R2 > .98), mainly due to [methyl-3H]choline-labelled dipalmitoyl-PC, in all experimental groups. In BALF from cftr(tmIHGU/m1HGU) mice, the [methyl-3H]choline label of total PC and individual PC species was significantly increased over control values after 24 hours, but not after 1.5 to 6 hours. Numbers and composition of BALF cells were not different between controls and cftr(tmIHGU/m1HGU) mice. We, conclude that increased alveolar phospholipid in cftr(tmIHGU/m1HGU) mice is likely due to decreased reuptake of surfactant.

Comparison of Heliox and Oxygen as Washing Gases for the Nitrogen Washout Technique in Preterm Infants

The nitrogen washout technique usually involves exposure of the patient to 100% oxygen for several minutes. This may be dangerous in preterm infants who are at risk of retinopathy of prematurity (ROP). We wanted to know whether heliox (79% He, 21% O2) can be used instead of oxygen when determining functional residual capacity (FRC). FRC measurements were made in 14 preterm infants [median (range) gestational age at birth 34 wk (27-37 wk), and at time of study 36 wk (33-40 wk)] who were breathing room air. FRC was measured using a computerized infant pulmonary function system, beginning in random order with either 100% O2 followed by heliox or vice versa. There was no systematic difference between the two methods with regard to lung volume measurements: mean (SD) FRC values, corrected for body weight, were 22.9 (7.1) mL/kg for O2 and 23.4 (7.0) mL/kg for heliox. We did not observe a systematic influence of the type of washing gas used (heliox or oxygen) on FRC in these infants. Our results suggest that the use of heliox instead of pure oxygen may be a suitable and safer alternative for FRC measurements with the nitrogen washout technique in preterm infants who are breathing low concentrations of inspired oxygen and are still at risk of ROP.