Heat susceptibility of interleukin-10 and other cytokines in donor human milk.

OBJECTIVE: Holder pasteurization renders donor human milk safe for consumption. Because human milk reduces the risk of necrotizing enterocolitis in preterm infants, we tested whether Holder pasteurization affects certain factors in human milk that protect the intestines: epidermal growth factor (EGF), transforming growth factor (TGF)-beta1, erythropoietin (EPO), and interleukin (IL)-10. Donor human milk from a milk bank was examined. METHODS: The aqueous phase of 17 samples of donor term human milk (mean duration of lactation, 8 +/- 3.5 months) was examined before and after Holder pasteurization. In the case of IL-10, lesser degrees of pasteurization were also evaluated. The agents were quantified using enzyme immunoassays. The function of IL-10 was also tested. RESULTS: Concentrations of EGF and IL-10 were markedly lower than previously reported values in human milk from earlier phases of lactation. Holder pasteurization significantly reduced the concentrations of EPO and IL-10, whereas lesser degrees of heating increased the detection of IL-10. The immunosuppression of T-cell proliferation by human milk, thought to be attributed to IL-10 alone, persisted after Holder pasteurization. CONCLUSIONS: Holder pasteurization greatly decreased concentrations of EPO and IL-10 in human milk. These decreases may impact the ability of human milk to protect against necrotizing enterocolitis. Evidence of possible binding of IL-10 to other proteins in human milk was also found. Experiments to test whether Holder pasteurization affects the function of IL-10 in human milk produced evidence for an agent in human milk other than IL-10 that inhibits T-cell proliferation and resists Holder pasteurization.

Maternal factors in extremely low birth weight infants who develop spontaneous intestinal perforation.

BACKGROUND: Spontaneous intestinal perforation of the extremely low birth weight infant (< or = 1000 g) is associated with a high incidence of Candida and coagulase-negative Staphylococcus sepsis. Little is known about prenatal risk factors, and histopathologic examination of placentas in infants with spontaneous intestinal perforation has not been reported. OBJECTIVES: Our objective was to investigate maternal factors and specific placental findings in a sample of infants with spontaneous intestinal perforation. We compared the maternal factors and clinical outcomes to a matched control group. PATIENTS AND METHODS: This single-center, retrospective cohort study was conducted between January 2001 and December 2005. The records of extremely low birth weight infants with spontaneous intestinal perforation were reviewed (n = 16). Study infants were matched to 2 infants in the control group; any twin of a study patient was also included as a control subject (n = 35). Histopathologic examination of placentas included standard hematoxylin and eosin and methenamine silver stains. RESULTS: Infants with spontaneous intestinal perforation were more likely than control subjects to have severe placental chorioamnionitis with fetal vascular response (40% vs 12%); 2 placentas also tested positive for yeast versus none in the control subjects. Mothers of infants with spontaneous intestinal perforation were more likely than control subjects to have received antibiotics before or at delivery (93% vs 57%). Fifty percent of the infants had Candida, and 31% in the spontaneous intestinal perforation group had coagulase-negative Staphylococcus sepsis versus 6% in the control subjects. Finally, infants with spontaneous intestinal perforation had delayed enteral feeding (64 +/- 30 vs 31 +/- 10 days) and prolonged hospitalization (155 +/- 48 vs 108 +/- 36 days). CONCLUSIONS: Spontaneous intestinal perforation in the extremely low birth weight infant is a neonatal disease related to placental inflammation. We alert practitioners to the importance of placental findings, because they may be positive for yeast.

Arteriovenous CO2 removal improves survival compared to high frequency percussive and low tidal volume ventilation in a smoke/burn sheep acute respiratory distress syndrome model.

UNLABELLED: OBJECTIVES AND SUMMARY BACKGROUND: Low tidal volume ventilation (LTV) has improved survival with acute respiratory distress syndrome (ARDS) by reducing lung stretch associated with volutrauma and barotrauma. Additional strategies to reduce lung stretch include arteriovenous carbon dioxide removal (AVCO2R), and high frequency percussive ventilation (HFPV). We performed a prospective, randomized study comparing these techniques in our clinically relevant LD100 sheep model of ARDS to compare survival, pathology, and inflammation between the 3 ventilator methods. METHODS: Adult sheep (n = 61) received smoke inhalation (48 breaths) and a 40% third-degree burn. After ARDS developed (Pao2/FiO2 <200), animals were randomized. In experiment 1, animals were killed at 48 hours after randomization. Hemodynamics, pulmonary function, injury scores, myeloperoxidase (MPO) in lung tissues and neutrophils, IL-8 in lung tissues, and apoptosis were evaluated. In experiment 2, the end point was survival to 72 hours after onset of ARDS or end-of-life criteria with extension of the same studies performed in experiment 1. RESULTS: There were no differences in hemodynamics, but minute ventilation was lower in the AVCO2R group and Paco2 for the HFPV and AVCO2R animals remained lower than LTV. Airway obstruction and injury scores were not different among the 3 ventilation strategies. In experiment 1, lung tissue MPO and IL-8 were not different among the ventilation strategies. However, in experiment 2, lung tissue MPO was significantly lower for AVCO2R-treated animals (AVCO2R < HFPV < LTV). TUNEL staining showed little DNA breakage in neutrophils from experiment 1, but significantly increased breakage in all 3 ventilator strategies in experiment 2. In contrast, AVCO2R tissue neutrophils showed significant apoptosis at 72 hours post-ARDS criteria as measured by nuclear condensation (P < 0.001). Survival 72 hours post-ARDS criteria was highest for AVCO2R (71%) compared with HFPV (55%) and LTV (33%) (AVCO2R vs. LTV, P = 0.05). CONCLUSIONS: Significantly more animals survived AVCO2R than LTV. In experiment 2, Lung MPO was significantly lower for AVCO2R, compared with LTV (P < 0.05). This finding taken together with the TUNEL and neutrophil apoptosis results, suggested that disposition of neutrophils 72 hours post-ARDS criteria was different among the ventilatory strategies with neutrophils from AVCO2R-treated animals removed chiefly through apoptosis, but in the cases of HFPV and LTV, dying by necrosis in lung tissue.

Lipopolysaccharide protection from oxygen toxicity: effect on rat pulmonary selectins.

Sublethal doses of LPS result in increased tolerance to high concentrations of oxygen and this is associated with decreased pulmonary inflammation in a rat model. To investigate the mechanism of decreased neutrophil influx into the lung in this model, we measured levels of mRNA in the lung for the endothelial adhesion molecules, E-selectin and P-selectin. Immunostaining for E-selectin protein was also done in rat lungs, as well as measurement of soluble L-selectin in the blood. These levels were measured in the lungs of adult rats injected with 0.5 mg/kg LPS or placebo at 0 and 24 h and exposed to > 95% O2 for 60 h. Oxygen exposure resulted in significant increases in both E- and P-selectin mRNA and in E-selectin protein after 60 h. LPS resulted in an early rise in E-selectin protein followed by a decline to less than control (saline/O2) levels at 60 h. Messenger RNA for E-selectin followed a similar trend, although there were no differences at 60 h between LPS and control groups exposed to O2. P-selectin mRNA expression did not significantly differ between LPS and control O2 groups. Soluble L-selectin levels decreased by 6 h after LPS infusion and were significantly lower than saline/O2 controls through 24 h, suggesting binding to endothelium. In conclusion, the decrease in E-selectin expression on the surface of pulmonary endothelium after LPS could contribute to decreased inflammation in this model of oxygen toxicity. Soluble L-selectin may serve a further anti-inflammatory role after LPS infusion by binding to pulmonary endothelium.

Meconium obstruction in the very low birth weight premature infant.

Meconium obstruction of prematurity is a distinct clinical condition that occurs in very low birth weight infants, predisposing them to intestinal perforation and a prolonged hospitalization if not diagnosed and treated promptly. We report a series of 21 infants, including 2 detailed case reports, whose clinical course is indicative of meconium obstruction of prematurity. Specific risk factors are identified along with descriptions of clinical and radiologic findings, disease course, treatment, and outcome. Meconium obstruction of prematurity was more common in infants with a maternal history of pregnancy-induced or chronic hypertension, suggesting the possibility of decreased intestinal perfusion prenatally. Inspissated meconium was located most frequently in the distal ileum, making this disease process difficult to treat. Gastrografin enemas were safe, diagnostic, and therapeutic. Delay in diagnosis and treatment was associated with perforation and delay in institution of enteral feeds.

Effects of postnatal dexamethasone on oxygen toxicity in neonatal rats.

We investigated the effect of timing of early postnatal dexamethasone on survival of hyperoxia-exposed neonatal rats. Pups <24 h old were treated with a tapering course of dexamethasone or saline beginning either prior to exposure (day 0), or after 2, 4, or 6 days of > or =98% O2 (n=11-14) or air (n=8-11). Exposures were continued for 14 days. By day 14, day 0 pups had poor survival regardless of the exposure (14% in O2, 13% in air). Survival of pups treated with dexamethasone after 2, 4 and 6 days of O2 exposure was significantly higher at 14 days (50, 86 and 79%, respectively) compared to saline O2 controls (9%, p < 0.001 for each). Pulmonary biochemical analyses were conducted after exposure for 7 days in rat pups treated with dexamethasone or saline beginning after 4 days of exposure to air or O2 (n=11-12 for each group). While pups treated with dexamethasone showed greatly improved survival compared to O2 controls, there was no decrease in neutrophil influx into the lung as measured by lung myeloperoxidase and neutrophil counts in histologic specimens and lavage fluid. Catalase, glutathione peroxidase, total and manganese superoxide dismutase activities as well as manganese superoxide dismutase (MnSOD) mRNA expression were elevated in both O2 groups after 7 days compared to the air groups (p < 0.05) and MnSOD mRNA expression was elevated in the O2/dexamethasone group, but there were no differences between dexamethasone and saline groups in O2. Thus, this study indicates that the timing of dexamethasone administration is crucial. Mechanisms other than increases in antioxidant enzymes or decreases in lung neutrophils underlie the ability of dexamethasone to improve survival of these neonatal rats.

Neutrophil adhesion molecule expression in the developing neonatal rat exposed to hyperoxia.

Neonatal rats have an increased tolerance to hyperoxia, which is associated with a diminished pulmonary inflammatory response compared with adults. To investigate this differing response, expression of the neutrophil adhesion molecules, L-selectin and CD18, and levels of soluble L-selectin, were examined using flow cytometry and sandwich enzyme-linked immunosorbent assay on air-exposed neonatal rat neutrophils at 0-24 and 72 h and 7, 10, 14, and 21 d of age compared with the adult and after exposure to hyperoxia (>/= 98% O2) for 56 h in adults and for 72 h and 7 d in neonates. Expression of L-selectin in 0-24-h neonates was similar to adults, but was significantly lower than adults at 72 h and 7 d (P = 0.011). Soluble L-selectin levels were significantly higher than those in adults in the 0-24- and 72-h neonates (P < 0.001). CD18 expression in unstimulated and activated neutrophils of neonatal rats was higher at 0-24 h than in the adult (P < 0.001), but thereafter did not differ from adults. After hyperoxic exposure, L-selectin did not differ between the exposure groups but soluble L-selectin tended to increase in neonates after 7 d of O2 exposure Finally, CD18 was significantly higher after hyperoxic exposure of the adult (P = 0.008), but did not change with oxygen exposure in the neonate. Based on these findings, we speculate that differences between neonatal and adult rats in expression of L-selectin may contribute to delayed oxygen toxicity in neonatal rats.

Comparison of L-selectin and CD11b on neutrophils of adults and neonates during the first month of life.

The newborn infant is particularly susceptible to infection in the first weeks of life and this may be, in part, related to functional impairment of neonatal neutrophils in regard to adherence, chemotaxis, and migration. Differences in expression of the neutrophil adherence molecules, L-selectin and CD11b/CD18 (Mac-1), have been previously demonstrated in cord blood and in very young infants (

Endotoxin protection from oxygen toxicity: effect on pulmonary neutrophils and L-selectin.

The mechanisms by which sublethal doses of endotoxin protect against hyperoxic lung injury are not completely understood. We hypothesized that endotoxin treatment would result in a decreased inflammatory response to hyperoxia and that this would be accompanied by activation of neutrophils (as evidenced by loss of L-selectin) in the peripheral circulation. Adult rats were injected with endotoxin 0.5 mg/kg prior to and 24 hr after onset of exposure to > or = 98% O2. After 56 hr of hyperoxia, pulmonary neutrophils were lower in the O2/endotoxin group compared to O2 controls as measured by myeloperoxidase in lung homogenates and neutrophil counts in bronchoalveolar lavage fluid. Circulating neutrophils were also significantly lower in the O2/endotoxin group compared to O2 controls at 56 hr. Expression of the neutrophil adhesion molecule, L-selectin, was lower at 4 and 24 hr in the endotoxin-treated rats compared to O2 controls. There were no differences at 48 hr. Expression of CD18 rose significantly in the O2/endotoxin group after 4 hr, but thereafter did not differ from O2 controls. In summary, endotoxin protection from O2 toxicity was associated with reduced neutrophils in the lung and a loss of L-selectin from peripheral blood neutrophils.