Tanya Russell

Bifidobacterial supplementation reduces the incidence of necrotizing enterocolitis in a neonatal rat model

BACKGROUND & AIMS Neonatal necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease of premature infants partly caused by intestinal bacterial proliferation. Because bifidobacteria are thought to reduce the risk for intestinal disturbances associated with pathogenic bacterial colonization, we hypothesized that exogenous bifidobacterial supplementation to newborn rats would result in intestinal colonization and a reduction in the incidence of neonatal NEC. METHODS Newborn rat pups were given Bifidobacterium infantis (10(9) organisms per animal daily), Escherichia coli, or saline control and exposed to the NEC protocol consisting of formula feeding (Esbilac; 200 cal. kg(-1). day(-1)) and asphyxia (100% N(2) for 50 seconds followed by cold exposure for 10 minutes). Outcome measures included stool and intestinal microbiological evaluation, gross and histological evidence of NEC, plasma endotoxin concentration, intestinal phospholipase A(2) expression, and estimation of intestinal mucosal permeability. RESULTS Bifidobacterial supplementation resulted in intestinal colonization by 24 hours and appearance in stool samples by 48 hours. Bifidobacteria-supplemented animals had a significant reduction in the incidence of NEC compared with controls and E. coli-treated animals (NEC, 7/24 B. infantis vs. 19/27 control vs. 16/23 E. coli; P < 0.01). Plasma endotoxin and intestinal phospholipase A(2) expression were lower in bifidobacteria-treated pups than in controls, supporting the role of bacterial translocation and activation of the inflammatory cascade in the pathophysiology of NEC. CONCLUSIONS Intestinal bifidobacterial colonization reduces the risk of NEC in newborn rats.

Evaluation of nitric oxide as a mediator of severe preeclampsia

OBJECTIVE Our purpose was to determine whether a reduction in nitric oxide synthesis occurs in women with severe preeclampsia as a consequence of soluble serum factors. STUDY DESIGN Circulating nitrate and nitrite levels were compared between women who met standard clinical criteria for severe preeclampsia (n = 21) and maternal or gestational age-matched, normotensive, primagravid control subjects (n = 21). End-products of nitric oxide synthesis were measured from venous blood samples using nitrate reduction and chemiluminescence. To detect in vitro suppression of nitric oxide synthesis, human umbilical vein endothelial cell monolayers were grown to confluence and exposed to culture media containing 20% severe preeclamptic or control sera. Nitrate and nitrite production were compared in duplicate monolayers for each experimental condition, expressed as means +/- SEM in picomoles per 10(6) cells. Data were compared by Students t or Mann-Whitney U tests, when appropriate, along with Spearman correlations for comparisons of laboratory and clinical data. RESULTS Circulating nitrate and nitrite levels were similar in normotensive and preeclamptic cohorts (976 +/- 88 vs 1009 +/- 41 pmol/ml, respectively; p = 0.22), and no correlations between blood pressure and nitric oxide metabolite levels were observed for the control or severely preeclamptic subsets. Similar patterns of in vitro endothelial nitrite production were observed after 1-, 12-, and 24-hour incubations with 20% control or preeclamptic sera. CONCLUSIONS Circulating nitrate and nitrite levels are not reduced in patients with severe preeclampsia compared with normotensive controls, and sera from these women do not suppress endothelial cell nitric oxide synthesis in vitro.

Effect of Polyunsaturated Fatty Acid (PUFA) Supplementation on Intestinal Inflammation and Necrotizing Enterocolitis (NEC) in a Neonatal Rat Model

Inasmuch as long-chain polyunsaturated fatty acids (PUFA, metabolites of the essential n-3 and n-6 fatty acids) are known to modulate inflammation, we hypothesized that supplementation of formula with these compounds would prevent necrotizing enterocolitis (NEC) and intestinal inflammation in our neonatal rat model. Newborn rats were stressed with asphyxia and formula feeding, and randomly assigned to control formula, control with PUFA supplementation, and PUFA with nucleotides. Animals were followed for 72–96 h and assessed for death, gross and histologic NEC, intestinal apoptosis, endotoxemia, and intestinal mRNA synthesis of phospholipase A2-II (rate-limiting enzyme for platelet activating factor production), platelet activating factor receptor, and inducible nitric oxide synthase. We found that PUFA reduced the incidence of death and NEC compared with the other groups (NEC 8 of 24 versus 17 of 24 control and 13 of 23 PUFA + nucleotides, p < 0.05). Furthermore, PUFA reduced plasma endotoxemia at 48 h (25 ± 4 EU/mL versus 276 ± 39 EU/mL in control and 170 ± 28 EU/mL in PUFA + nucleotide), intestinal phospholipase A2-II expression at 24 h, and platelet activating factor receptor expression at 48 h. Formula supplementation had no effect on apoptosis of intestinal epithelium or intestinal inducible nitric oxide synthase expression. Addition of nucleotides with PUFA abrogated the beneficial effects of PUFA on intestinal inflammation. We conclude that PUFA reduces the incidence of NEC and intestinal inflammation in a neonatal rat model.

Serum from patients with severe preeclampsia is not cytotoxic to endothelial cells.

OBJECTIVE We evaluated the hypothesis that circulating factors in preeclampsia promote direct endothelial cell injury using an in vitro index of cytotoxicity. METHODS Subconfluent umbilical vein endothelial cell monolayers were established and radiolabeled with chromium (51Cr), then randomly exposed for 24 hours in triplicate to 20% sera from nonlaboring patients with severe preeclampsia (n = 5) or mild preeclampsia and normotensive controls (n = 5). Additional experiments were performed by exposing endothelial monolayers to sera for 3 and 48 hours, and under hypoxic conditions (1% oxygen). Cytotoxicity was defined by the percentage of 51Cr release, expressed as the ratio of radioactivity in the supernatant to the maximum cell-associated radioactivity. RESULTS Mean 51Cr release was similar in all experiments comparing preeclamptic and normal sera. Although consistently greater 51Cr release was noted in hypoxic as compared with normoxic incubations, no differences in cytotoxicity were identified among severe preeclampsia, mild preeclampsia, and normal sera in hypoxia. CONCLUSION Sera from patients with preeclampsia do not appear to be cytotoxic to vascular endothelium in this in vitro model.

Bifidobacteria Supplementation Prevents NEC in Newborn Rats by Modulation of the Inflammatory Cascade • 566

Bifidobacteria Supplementation Prevents NEC in Newborn Rats by Modulation of the Inflammatory Cascade • 566

FORMULA FEEDING AND ASPHYXIA STIMULATES APOPTOSIS OF INTESTINAL EPITHELIAL CELLS AND ALTERATIONS IN MUCOSAL PERMEABILITY IN NEONATAL RATS ♦ 470

FORMULA FEEDING AND ASPHYXIA STIMULATES APOPTOSIS OF INTESTINAL EPITHELIAL CELLS AND ALTERATIONS IN MUCOSAL PERMEABILITY IN NEONATAL RATS ♦ 470

Cost savings and perinatal outcome associated with outpatient management of triplet pregnancy

OBJECTIVE Our goal was to compare the lengths of hospitalization and the perinatal outcomes of triplet pregnancies managed with either outpatient or inpatient third-trimester bed rest. STUDY DESIGN Thirty-two triplet pregnancies in which outpatient bed rest was prescribed (April 1993 to April 1996) were compared with a historic cohort of 34 triplets (January 1985 to March 1993) in which routine hospitalization was undertaken in the third trimester. Length of hospitalization and maternal and neonatal outcome parameters were compared between groups. RESULTS Maternal inpatient hospital days were significantly reduced for the group managed as outpatients, but combined maternal and neonatal hospitalization was similar between groups. The mean gestational age at delivery was 1 week greater in the hospitalized cohort (33.5+/-2.8 vs 32.5+/-2.8, respectively; p=0.16), and average birth weight was correspondingly greater in hospitalized cases (1942 gm vs 1718 gm, p < 0.005). Neonatal lengths of stay were similar between groups, reflecting earlier postnatal discharge in the outpatient era of this study. Preeclampsia occurred with greater frequency in the outpatient group (31.3% vs 8.8%, p=0.02), and the neonatal complication of intraventricular hemorrhage occurred more commonly in this cohort as well (10/96 vs 1/102, p=0.004). All other maternal and neonatal complications were similar between groups. CONCLUSION Reduction in the length of hospitalization attributable to outpatient management was limited to the maternal length of stay. It is possible that the observed maternal and neonatal complications in the outpatient group may have been related to less rigorous bed rest. We would suggest that the differences noted in preeclampsia, birth weight, and intraventricular hemorrhage support prospective evaluation of bed rest in triplet pregnancy.