The evaluation of the fetal fibronectin test for prediction of preterm delivery in symptomatic patients.

OBJECTIVE: This study was conducted to evaluate the usefulness of testing for fetal fibronectin (fFN) to rule out the diagnosis of preterm labour in symptomatic patients in a Canadian setting. METHODS: This was a prospective, blinded clinical evaluation of fFN testing in women presenting with threatened preterm labour at between 24 and 34 weeks' gestation at two Canadian tertiary care centres. RESULTS: Of the 149 women tested, 32 had a positive fFN test. In the total patient population, 10.1% delivered within seven days of testing, and 18.2% delivered prior to 34 weeks. A negative fFN result was associated with a 97.4% likelihood of delivering more than seven days after testing and with a 91.4% chance of delivering after 34 weeks. CONCLUSION: The fFN test appears to provide useful information in the risk assessment of Canadian women presenting with symptoms compatible with preterm labour. A negative test has a high predictive value for delivering more than seven days after presentation.

Reduced bile flow associated with parenteral nutrition is independent of oxidant load and parenteral multivitamins.

BACKGROUND: Reduction in bile flow is a characteristic of cholestasis related to parenteral nutrition. Light exposure of parenteral multivitamin preparations is the major source of peroxides contaminating parenteral nutrition solutions. They may contribute to local oxidative stress. Oxidants are reported to affect transport mechanisms across the hepatocyte membrane into bile. The authors hypothesize that an oxidant-antioxidant imbalance is involved in parenteral nutrition related cholestasis. The aim of this study was to investigate the roles of multivitamin preparations and peroxides on bile flow in newborn guinea pigs receiving parenteral nutrition. METHODS: Three-day-old guinea pigs were fed enterally or parenterally with solutions containing 8% dextrose/0.45% NaCl +/- multivitamin preparation +/- amino acids +/- lipids. The influence of the oxidant-antioxidant balance on bile flow was evaluated using 500 microM hydrogen peroxide and 1% and 3% multivitamin preparations +/- Na metabisulfite. Four days later, animals were anesthetized and bile flow was recorded over 2 hours. Glutathione determinations were performed on bile and liver samples. The percentage of oxidized glutathione, reflecting the redox status, was used as a marker of oxidative stress. Data were compared by analysis of variance with P < 0.05. RESULTS: Bile flow decreased first on initiating dextrose + NaCl infusion (a 25% decrease) and subsequently by adding amino acids (a further 30% decrease). Although antioxidant vitamins and peroxides modified the hepatic redox status, they did not influence bile flow. CONCLUSION: Although the composition of parenteral nutrition affects bile flow and the hepatic redox status, the oxidant-antioxidant imbalance in infused solutions is not the causal event in the installation of cholestasis.

Photooxidation of parenteral multivitamins induces hepatic steatosis in a neonatal guinea pig model of intravenous nutrition.

Photooxidation of multivitamin solutions results in the generation of peroxides. Because peroxides are associated with hepatic steatosis and fibrosis as well as cholestasis, we questioned whether multivitamins are implicated in hepatic complications of parenteral nutrition. Guinea pig pups were assigned to groups receiving intravenously either total parenteral nutrition, photo-protected or not, or a control solution (5% dextrose + 0.45% NaCl) supplemented with either a) multivitamins; b) photo-protected multivitamins; c) multivitamins without riboflavin; or d) peroxides (H(2)O(2), tert-butylhydroperoxide). After 4 d, liver was sampled for histology and isoprostane-F(2alpha) levels, a marker of radical attack. Multivitamins as well as total parenteral nutrition were associated with steatosis (scored 0-4), the severity of which was reduced (p < 0.05) by photo protection. Although H(2)O(2) is the major peroxide contaminating multivitamins, it did not induce steatosis scores different than the controls. Compared with controls, hepatic isoprostane-F(2alpha) content increased in animals infused with H(2)O(2) (p < 0.05), but not in those infused with Multi-12 pediatric multivitamins or total parenteral nutrition. Results suggest that peroxides and/or free radicals are not mediators of the induction of steatosis observed with infusion of photo-exposed multivitamins, as there was no correspondence between histologic findings and hepatic levels of isoprostanes. It is suspected that a component of the multivitamin solution becomes hepato-toxic after photo-exposure, as indicated by the protective effect observed when withdrawing riboflavin. Photo-oxidation of multivitamins might be the common link between reports involving amino acids, lipids, and light exposure in the ethiology of hepatic complications of parenteral nutrition.

An evaluation of three glucose meter systems and their performance in relation to criteria of acceptability for neonatal specimens.

BACKGROUND: Prior to making a selection for our hospital, a pediatric institution, we deemed it necessary to evaluate, concurrently, three recently available glucose meter systems, claimed to be suitable for use with neonatal samples. METHODS: Comparisons were with laboratory plasma analyses. Linearity and precision were also determined. RESULTS: All meters gave linear responses. Precision determined using quality control material was acceptable. For an in-laboratory side-by-side evaluation, meter 1 showed a small bias but significant result scatter while meter 3 showed a negative bias; mean differences from reference (S.D.) were: -0.30 mmol/l (0.56), 0.06 mmol/l (0.39) and -0.49 mmol/l (0.35) for meters 1, 2 and 3, respectively. Clinical unit testing results gave mean differences from reference (S.D.) of: -0.19 mmol/l (0.56), 0.06 mmol/l (0.48) and -0.12 mmol/l (0.48) for meters 1, 2 and 3, respectively. Using +/- 15% of reference as acceptability thresholds, 61%, 79% and 72% of results for meters 1, 2 and 3 respectively, were within limits. At +/- 20%, the corresponding figures were 81%, 90% and 91%, respectively. All meters showed a sample-hematocrit effect with either negative (meters 1 and 3) or positive (meter 2) bias. CONCLUSIONS: Regardless of the performance criteria chosen, meter 1 had the worst performance while meter 2 was slightly better in overall than meter 3. Based on performance, general characteristics and user feedback, meter 2 was selected by us. In light of our results, we nonetheless suggest that performance of the meters tested is less than ideal, especially in the context of clinical utility in neonates.