Modification of WS2thin film properties using high dose gamma irradiation.

The tunability of the transition metal dichalcogenide properties has gained attention from numerous researchers due to their wide application in various fields including quantum technology. In the present work, WS2has been deposited on fluorine doped tin oxide substrate and its properties have been studied systematically. These samples were irradiated using gamma radiation for various doses, and the effect on structural, morphological, optical and electrical properties has been reported. The crystallinity of the material is observed to be decreased, and the results are well supported by x-ray diffraction, Raman spectroscopy techniques. The increase in grain boundaries has been supported by the agglomeration observed in the scanning electron microscopy micrographs. The XPS results of WS2after gamma irradiation show evolution of oxygen, carbon, C=O, W-O and SO4-2peaks, confirming the addition of impurities and formation of point defect. The gamma irradiation creates point defects, and their density increases considerably with increasing gamma dosage. These defects crucially altered the structural, optical and electrical properties of the material. The reduction in the optical band gap with increased gamma irradiation is evident from the absorption spectra and respective Tauc plots. TheI-Vgraphs show a 1000-fold increase in the saturation current after 100 kGy gamma irradiation dose. This work has explored the gamma irradiation effect on the WS2and suggests substantial modification in the material and enhancement in electrical properties.

Benefits of routine probiotic supplementation in preterm infants.

AIM: We introduced routine probiotic supplementation (RPS) of preterm infants in June 2012. We previously reported that RPS reduced the incidence of necrotising enterocolitis (NEC) and mortality in such infants. In this study, we assessed if the benefits of RPS were sustained for infants in the current era. METHOD: We compared the outcomes of preterm infants in recent epoch 3 (RPS, 1st June 2014 to 31st December 2019) versus epoch 2 (RPS, 1st June 2012 to 31st May 2014) and epoch 1 (no RPS, 1st December 2008 to 30th November 2010). Multiple logistic and Cox regression models were used to compare the outcomes. RESULTS: There were 645 infants in epoch 1, 712 in epoch 2 and 1715 in epoch 3. Age at full feeds was significantly lower in epoch 3 vs. 2 and epoch 3 vs. 1 in infants <28 weeks of gestation. NEC and late-onset sepsis (LOS) were significantly lower in epoch 3 vs. 1 in infants <28 weeks. LOS and age at full feeds were significantly lower in epoch 3 vs. 2 and epoch 3 vs. 1 in infants with gestation 28 to 32 weeks. CONCLUSION: The benefits associated with RPS were sustained during epoch 3.

Efficacy of interventions to improve hand hygiene compliance in neonatal units: a systematic review and meta-analysis.

Healthcare-associated infections (HCAIs) cause significant morbidity and mortality in neonatal intensive care units (NICUs). Meticulous hand hygiene is the most effective strategy to prevent HCAI. However, hand hygiene compliance (HHC) is low, especially in ICUs. Hence, we aimed to evaluate the efficacy of strategies for improving HHC in NICUs. A systematic review of the literature and meta-analysis were carried out. PubMed, EMBASE, Cochrane CENTRAL and CINAHL were searched in October 2013. PRISMA guidelines were followed. The quality of included studies was assessed by the Newcastle-Ottawa scale (NOS). Sixteen eligible non-randomised studies were included. A total of 27,155 hand hygiene moments were observed. Meta-analysis using a random effects model indicated that a range of strategies, such as educational campaigns, musical parodies, reminders, easy access to hand hygiene sanitisers, UV sensors and performance feedback, improved HHC [odds ratio (OR) 2.04; 95 % confidence interval (CI) 1.40, 2.97]. Significant statistical heterogeneity was noted. Studies which specifically provided performance feedback at either the individual or group levels reported a more significant improvement in HHC compared to those that did not (OR 2.81; 95 % CI 1.32, 5.96 vs. OR 1.55; 95 % CI 1.13-2.11). Strategies to improve HHC in NICUs seem to be more effective when they include performance feedback at the personal or group levels. Randomised controlled trials (RCTs) specifically assessing the benefits of performance feedback in improving HHC are needed.

Comparison of Papile versus Laterality-Based Al-Abdi System to Predict Neurodevelopmental Impairment in Extreme Preterm Infants after Severe Germinal Matrix Hemorrhage-Intraventricular Hemorrhage: A Retrospective Comparative Observational Study.

BACKGROUND AND PURPOSE: The traditional Papile classification system for severe germinal matrix hemorrhage-intraventricular hemorrhage is limited in objectivity and interrater variability for accurate prediction of neurodevelopmental impairment in extremely preterm infants. Many extremely preterm infants with severe germinal matrix hemorrhage-intraventricular hemorrhage are still offered "redirection of care" in spite of the recent evidence suggesting that many of these infants can have normal outcomes. Therefore, it is important to consider the laterality and extent of brain hemisphere involvement while classifying severe germinal matrix hemorrhage-intraventricular hemorrhage to predict neurodevelopmental impairment. The aim of the present study was to compare the Al-Abdi system with the Papile system for their accuracy in predicting neurodevelopmental impairment in extremely preterm infants with severe germinal matrix hemorrhage-intraventricular hemorrhage. MATERIALS AND METHODS: This is a retrospective study of extremely preterm infants with severe germinal matrix hemorrhage-intraventricular hemorrhage admitted to a tertiary neonatal intensive care unit (2006-2016). Cranial sonograms were independently re-reviewed by 2 radiologists as per the Al-Abdi system. The prognostic statistical indices for both systems to predict neurodevelopmental impairment were calculated. RESULTS: A total of 91 infants with severe germinal matrix hemorrhage-intraventricular hemorrhage survived, and 83 (median gestational age, 26.3 weeks; and median birth weight, 890 g) completed developmental assessment. The receiver operating characteristic areas under the curve to predict neurodevelopmental impairment by the Papile versus Al-Abdi systems were 0.702 versus 0.723, respectively (P = .474). Corresponding Al-Abdi cutoff scores of 19, 20, 21, and 22 demonstrated increased specificity (76.36%-85.45%) and correct classification (69.88%-72.29%) to predict moderate-to-severe neurodevelopmental impairment. CONCLUSIONS: The Al-Abdi system is comparable with the Papile system for predicting neurodevelopmental impairment for extremely preterm infants with severe germinal matrix hemorrhage-intraventricular hemorrhage, with higher Al-Abdi scores being more specific. This finding may prove useful for neonatal health care providers and parents in their decision regarding "continuation of care." Future multicentric studies are warranted to ascertain the validity of individual Al-Abdi scores.

Difficulties in developmental follow-up of preterm neonates in a randomised-controlled trial of Bifidobacterium breve M16-V - Experience from Western Australia.

BACKGROUND: Probiotics may be neuroprotective for preterm neonates due to their anti-inflammatory effects and ability to facilitate nutrition. AIM: To assess long-term effects of early probiotic supplementation on neuropsychological development in preterm infants. STUDY DESIGN: Follow up study. SUBJECTS: Children at age 3 to 5 years who had participated as preterm infants (<33 week) in the randomised controlled trial. OUTCOMES: Primary: Continuous early learning composite measure derived from the Mullen's Scale of Early Learning (MSEL). Other outcomes were assessed by the Developmental, Dimensional and Diagnostic Interview, Developmental NEuroPSYchological assessment-2nd Edition, Parental questionnaires using children's communication checklist-2nd edition, social responsiveness scale, and Vineland Adaptive Behavioural Scales-2nd edition. MEASURES: Continuous scores derived from all the measures. RESULTS: 67 children of the 159 participants (42%) (Probiotic: 36/79, Placebo: 31/80) were followed-up for at least one neuropsychological assessment. All six assessments were completed in 18/31 (58.1%) of the control vs. 11/36 (30.6%) probiotic group children. Multivariable analysis of MSEL composite score showed no evidence of probiotic effect univariately, or after adjustment for gestation, intrauterine growth restriction, Apgar <7 at 5 min and age at assessment (adjusted mean effect in probiotic group: -2.7, 95% CI -8.5-3.0, p = 0.349). CONCLUSION: There was no significant effect on neurodevelopment of children assessed at the age of 3 to 5 years who participated as preterm neonates in the RCT of B. breve M-16V. The validity of these results is limited by the reduced sample size due to high rate of loss to follow up.

Patterned carbon nanotube growth using an electron beam sensitive direct writable catalyst.

This paper reports the use of spin coatable Fe naphthenate (Fe(C(11)H(7)O(2))(2)) as an electron beam sensitive direct writable catalyst suitable for growing high quality carbon nanotubes (CNTs). Vertically aligned, densely packed, equal in height, three- to four-walled and 5-7 nm inner diameter CNTs were grown on the nanoscale stripe patterns by water-assisted chemical vapor deposition. The correlation between electron beam dosage and the growth characteristics of CNTs is also discussed.

Long-chain polyunsaturated fatty acid supplementation in preterm infants.

BACKGROUND: The n-3 and n-6 essential fatty acids alpha linolenic acid (ALA) and linoleic acid (LA) are the precursors of the n-3 and n-6 longchain polyunsaturated fatty acids (LCPUFA). Controversy exists over whether LCPUFA are essential nutrients for preterm infants, who may not be able to synthesise sufficient amounts of LCPUFA to satisfy the needs of the developing brain and retina. OBJECTIVES: The aim of this review is to assess whether supplementation of formula with LCPUFA is safe and of benefit to preterm infants. SEARCH STRATEGY: Trials were identified by MEDLINE (February 2007), Oxford Database of Perinatal Trials, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2007) and by checking reference lists of relevant articles and conference proceedings. SELECTION CRITERIA: All randomised trials of formula supplemented with LCPUFA and with clinical endpoints were reviewed. DATA COLLECTION AND ANALYSIS: Fifteen randomised trials assessing the clinical effects of feeding formula supplemented with LCPUFA were included in the review. MAIN RESULTS: Of the fifteen randomised trials included in the review, four of these were not classified as of high quality, due to low follow-up, uncertainty regarding concealment of patient allocation and randomisation, and problems with assessment methodology. VISUAL ACUITY: Visual acuity over the first year was measured by Teller or Lea acuity cards in eight studies, by VEP in six studies and by ERG in two studies. Most studies found no significant differences in any visual assessment between supplemented and control infants. DEVELOPMENT: Most of the trials have used Bayley Scales of Infant Development (BSID) at 12 to 24 months post-term with three out of seven studies reporting some benefit of LCPUFA in different populations of supplemented infants at different postnatal ages. Meta-analysis of BSID of four studies at 12 months (N = 364) and three studies at 18 months (N = 494) post-term showed no significant effect of supplementation on neurodevelopment. Carlson 1992 and Carlson 1996 demonstrated lower novelty preferences (possibly predictive of lower intelligence) in the supplemented compared with the control group. The investigators however concluded that supplemented infants may have more rapid visual information processing given that they had more looks and each look was of shorter duration. GROWTH: Four out of thirteen studies reported benefits of LCPUFA on growth of supplemented infants at different postnatal ages. Two trials (Carlson 1992; Carlson 1996) suggested that LCPUFA supplemented infants grow less well than controls, possibly due to a reduction in AA levels that occurs when n-3 supplements are used without n-6 supplements. Recent trials with addition of AA to the supplement have reported no significant negative effect on growth. Fewtrell 2002 reported mild reductions in length and weight z scores at 18 months. Contrary to these results, meta-analysis of five studies (Uauy 1990; Carlson 1996; Hansen 1997; Vanderhoof 1999; Innis 2002) showed increased weight and length at two months post-term in supplemented infants. Meta-analysis of four studies at 12 months (N = 271) and two studies at 18 months (N = 396) post-term showed no significant effect of supplementation on weight, length or head circumference. SIDE EFFECTS: Uauy 1992 reported no significant effect of LCPUFA supplementation on bleeding time and red cell membrane fragility. AUTHORS' CONCLUSIONS: Infants enrolled in the trials were relatively mature and healthy preterm infants. Assessment schedule and methodology, dose and source of supplementation and fatty acid composition of the control formula varied between trials. When the results of the RCT's are pooled, no clear long-term benefits were demonstrated for infants receiving formula supplemented with LCPUFA. There was no evidence that supplementation of formula with n-3 and n-6 LCPUFA impaired the growth of preterm infants.

Long-chain polyunsaturated fatty acid supplementation in infants born at term.

BACKGROUND: The n-3 and n-6 fatty acids linolenic acid and linoleic acid are precursors of the n-3 and n-6 long chain fatty acids (LCPUFA). Infant formula has historically only contained the precursor fatty acids. Controversy exists over whether LCPUFA are also essential nutrients in infancy. Over the last few years, some manufacturers have added LCPUFA to formulae and marketed them as providing an advantage for the development of term infants. OBJECTIVES: To assess whether supplementation of formula with LCPUFA is safe and of benefit to term infants. SEARCH STRATEGY: Eligible studies were identified by searching MEDLINE (March 2007), EMBASE 1980 - 2007, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2007) and CINAHL (December 1982 - March 2007). Abstracts of the Society for Pediatric Research were hand searched from 1980 to 2006 inclusive. Reference lists of published narrative and systematic reviews were also reviewed. No language restrictions were applied. SELECTION CRITERIA: All randomised and quasi randomised trials comparing LCPUFA supplemented formula milk vs. non-supplemented formula milk and with clinical endpoints were reviewed. DATA COLLECTION AND ANALYSIS: Methodological quality of eligible studies was assessed according to allocation concealment, blinding of intervention, blinding of outcome assessment and completeness of follow up. Data were sought regarding effects on visual acuity, neurodevelopmental outcomes and physical growth. When appropriate, meta-analysis was conducted to provide a pooled estimate of effect. Continuous data were analysed using weighted mean difference (WMD). There were no categorical outcomes in this review. MAIN RESULTS: Twenty randomised studies were identified. Fourteen were included (n = 1719) and six excluded. Eleven included studies were of good quality. The main outcomes assessed were visual acuity, neurodevelopmental and physical growth. Visual acuity was measured at various stages throughout the first three years of life by nine studies. Visual evoked potential was used to assess visual acuity in five studies. The remaining four used Teller visual acuity cards. The results were inconsistent. Three studies reported beneficial effect of LCPUFA supplementation on visual acuity while the remaining six did not. Neurodevelopmental outcome was measured at different ages throughout the first two years by eleven studies. Bayley scales of infant development (BSID) was used in eight studies. Only one showed beneficial effect of LCPUFA supplementation on BSID scales. Pooled meta-analysis of the data also did not show any statistically significant benefit of LCPUFA supplementation on either mental or psychomotor developmental index of BSID. One study reported better novelty preference measured by Fagan Infant test at nine months in supplemented infants compared with controls. Another study reported better problem solving at 10 months with supplementation. One study used Brunet and Lezine developmental test to assess the developmental quotient and did not find beneficial effects of LCPUFA supplementation. Physical growth was measured at various ages throughout first three years of life by twelve studies. Some studies reported the actual measurements while some reported the rate of growth over a time period. Some studies z scores. Irrespective of the type of LCPUFA supplementation, duration of supplementation and method of assessment, none of the individual studies found beneficial or harmful effects of LCPUFA supplementation. Meta-analysis of relevant studies also did not show any effect of LCPUFA supplementation on growth of term infants. AUTHORS' CONCLUSIONS: The results of most of the well conducted RCTS have not shown beneficial effects of LCPUFA supplementation of formula milk on the physical, visual and neurodevelopmental outcomes of infants born at term. Only one group of researchers have shown some beneficial effects on VEP acuity. Two groups of researchers have shown some beneficial effect on mental development. Routine supplementation of milk formula with LCPUFA to improve the physical, neurodevelopmental or visual outcomes of infants born at term can not be recommended based on the current evidence. Further research is needed to see if the beneficial effects demonstrated by Dallas 2005 trial of Birch et al can be replicated in different settings.

Effect of probiotics on C-reactive protein levels in preterm infants: Secondary analysis of a randomized controlled trial.

BACKGROUND: Excessive inflammation is associated with adverse outcomes in preterm infants. C- reactive protein (CRP) is a marker of inflammation/infection. Probiotics have anti-inflammatory properties. Randomized controlled trials (RCTs) in preterm infants have not reported effect of probiotics on CRP. AIM: To evaluate effect of probiotics on CRP in preterm infants who had participated in a RCT of Bifidobacterium breve (B. breve) m-16v. METHODS: Data on all infants (GA <33 weeks, n = 159) enrolled in the RCT was analyzed. For study purpose, CRP <15 mg/L and ≤10 mg/L was considered normal for the first week, and thereafter respectively. Mixed logistic regression modelling was used to assess probiotic effect on CRP levels. RESULTS: There were 1579 CRP measurements (Probiotic: 851 vs. Placebo: 728). Baseline characteristics and number [Median (IQR)] of CRP estimations per infant [l0 (5, 20) vs. 10 (6, 17), p = 0.861] were comparable between probiotic vs. placebo group. There was no significant difference in the proportion of infants with high CRP over time (treatment by weekly time points interaction, p = 0.187), and across all time points between probiotic and placebo group (adjusted OR: 1.62, 95% CI: 0.91-2.88, p = 0.102)CONCLUSION:B. breve m-16v did not decrease CRP levels in preterm infants born <33 weeks.

Does patent ductus arteriosus affect feed tolerance in preterm neonates?

Patent ductus arteriosus (PDA), especially PDA with sepsis, has been reported as a risk factor for feed intolerance in preterm neonates. In this study, the start to full feeds interval was found to be longest in preterm neonates (

Physical activity programs for promoting bone mineralization and growth in preterm infants.

BACKGROUND: Lack of physical stimulation may contribute to metabolic bone disease of preterm infants resulting in poor bone mineralization and growth. Physical activity programs in the presence of adequate nutrition might help to promote bone mineralization and growth. OBJECTIVES: The primary objective of this review was to assess whether physical activity programs in preterm infants improve bone mineralization and growth and reduce the risk of fractures. SEARCH STRATEGY: Following the standard search strategy of the Cochrane Neonatal Review Group, a search was conducted in September 2006 including PubMed, EMBASE, CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2006), cross-references and handsearching of abstracts of the Society for Pediatric Research and the International Journal of Sports Medicine. No language restrictions were applied. SELECTION CRITERIA: Randomized and quasi-randomized controlled trials comparing physical activity programs (extension and flexion, range-of-motion exercises for several minutes a day several days per week for at least two weeks) to no organized physical activity programs in preterm infants. Eligible studies included those that provided physical activity for the experimental group, with or without massage and/or tactile stimulation for both experimental and control groups, as well as information on at least one outcome of interest. DATA COLLECTION AND ANALYSIS: Two review authors independently performed searches and extracted data. All three review authors were involved in selection and assessment of quality of studies. The statistical methods included relative risk (RR), risk difference (RD) and number needed to treat (NNT) for dichotomous outcomes and weighted mean difference (WMD) for continuous outcomes, reported with 95% confidence intervals (CI). Heterogeneity was estimated by the I(2) statistic. A fixed effect model was used to pool data for meta-analyses. MAIN RESULTS: Six trials enrolling 169 preterm infants (gestational age 26 to 34 weeks) were included in this review. All were small (N = 20 - 49) single center studies evaluating daily physical activity for 3.5 to 4 weeks during initial hospitalization. The methodological quality and reporting of all trials was poor. None of them stated the methods of concealment of patient allocation, the method of randomization or attempted blinding of the intervention. Only two trials attempted blinding of outcome assessors for outcomes relevant to this review. Two trials (N = 55) demonstrated moderate short-term benefits of physical activity on bone mineralization at completion of the physical activity program. Data was not pooled for meta-analyses due to methodological differences. The only trial (N = 20) assessing long-term effects on bone mineralization showed no effect of physical activity administered during initial hospitalization on bone mineralization at 12 months corrected age. Meta-analysis from three trials (N = 78) demonstrated an effect of physical activity on daily weight gain (WMD 2.77 g/kg/d, 95% CI 1.62, 3.92). Data from two trials (N = 58) showed no effect on linear growth (WMD -0.04 cm/week, 95% CI -0.19, 0.11) or head growth (WMD -0.03 cm/week, 95% CI -0.14, 0.09) during the study period. The I(2) statistic suggested heterogeneity on the analysis of linear growth (p = 0.006, I(2) = 86.9%). None of the trials assessed fractures or other outcomes relevant to this review. Data was insufficient for subgroup analyses based on birth weight and calcium/phosphorus intake. AUTHORS' CONCLUSIONS: There is weak evidence from six small randomized trials of poor methodological and reporting quality that physical activity programs might promote moderate short-term weight gain and bone mineralization in preterm infants. The clinical importance of these findings is questionable given the small effect size and low baseline risk of poor bone mineralization and growth in study participants. Data is inadequate to assess harm or long term effects. Current evidence does not justify the standard use of physical activity programs in preterm infants. Further evaluation of this intervention in well designed trials incorporating extremely low birth weight infants who are at high risk of osteopenia is required. Future trials should report on adverse events and long term outcomes including fractures, growth, bone mineralization, skeletal deformities and neurodevelopmental impairment. These trials should address the possibility that nutritional intake (calories, protein, calcium, phosphorus) might modify the effects of physical activity.

Standardized feeding regimen for reducing necrotizing enterocolitis in preterm infants: an updated systematic review.

OBJECTIVE: A systematic review (2005) of observational studies has reported 87% reduction in the incidence of necrotizing enterocolitis (NEC) after introducing standardized feeding regimen (SFR) in preterm infants. Considering the many new studies in this field since 2005 and the continued health burden of NEC, we aimed to systematically review the incidence of NEC in preterm infants 'before' vs 'after' implementing a SFR. STUDY DESIGN: PubMed, EMBASE, CINAHL and E-abstracts from the Pediatric Academic Society meetings and other pediatric and neonatal conference proceedings were searched in May 2016. Observational studies reporting incidence of NEC before and after implementing a SFR were included. Relevant data were extracted independently by two reviewers. Meta-analysis was conducted using random effects model (REM) and results rechecked with fixed effects model. RESULTS: Pooled results from 15 observational studies (N=18 160) using REM showed that SFR significantly reduced the incidence of NEC (risk ratio 0.22; 95% confidence interval 0.13 to 0.36; P<0.00001; I2=74%). The results remained significant after comparing studies in two epochs (1978 to 2003 vs 2004 to 2016). CONCLUSION: SFR continues to be an important tool in prevention of NEC in preterm infants.

Renal impairment associated with indomethacin treatment for patent ductus arteriosus in extremely preterm neonates--is postnatal age at start of treatment important?

OBJECTIVE: To study serum creatinine (SCr) levels following indomethacin for patent ductus arteriosus (PDA) closure in extremely preterm neonates in relation to postnatal age at the start of treatment. METHODS: This was a retrospective (January 2000-December 2002) analysis of data on preterm neonates (gestation <29 weeks) who received indomethacin for PDA. Pre-existing renal malformation and/or impairment and high serum levels of nephrotoxic drugs were criteria for exclusion. RESULTS: Indomethacin was commenced at postnatal age <7 days and >or=7 days in 60 (group 1) and 30 (group 2) neonates, respectively. The median (Q1, Q3) gestational age and birth weight for group 1 and group 2 neonates were 25 (23, 27) vs. 25 (24, 26) weeks and 740 (620, 909) vs. 780 (663, 966) grams, respectively. Postnatal age <7 days at start of indomethacin was associated with higher baseline (0.083 (0.074, 0.090) vs. 0.073 (0.054, 0.083) mmol/L, p=0.001) and peak SCr levels (0.099 (0.089,0.109) vs. 0.090 (0.064, 0.104) mmol/L, p=0.015). Logistic regression analysis controlling for gestational age and baseline SCr level indicated that postnatal age >or=7 days was a risk factor for elevated SCr after indomethacin (OR=13.4, 95% CI: 3.8-46.6, p < 0.001). CONCLUSION: Postnatal age >or=7 days at the start of indomethacin is a predictor of a significant rise in SCr in extremely preterm neonates.

A kinetic model of the formation of organic monolayers on hydrogen-terminated silicon by hydrosilation of alkenes.

We have analyzed a kinetic model for the formation of organic monolayers based on a previously suggested free radical chain mechanism for the reaction of unsaturated molecules with hydrogen-terminated silicon surfaces (Linford, M. R.; Fenter, P. M.; Chidsey, C. E. D. J. Am. Chem. Soc 1995, 117, 3145). A direct consequence of this mechanism is the nonexponential growth of the monolayer, and this has been observed spectroscopically. In the model, the initiation of silyl radicals on the surface is pseudo first order with rate constant, ki, and the rate of propagation is determined by the concentration of radicals and unreacted Si-H nearest neighbor sites with a rate constant, kp. This propagation step determines the rate at which the monolayer forms by addition of alkene molecules to form a track of molecules that constitute a self-avoiding random walk on the surface. The initiation step describes how frequently new random walks commence. A termination step by which the radicals are destroyed is also included. The solution of the kinetic equations yields the fraction of alkylated surface sites and the mean length of the random walks as a function of time. In mean-field approximation we show that (1) the average length of the random walk is proportional to (kp/ki)1/2, (2) the monolayer surface coverage grows exponentially only after an induction period, (3) the effective first-order rate constant describing the growth of the monolayer and the induction period (kt) is k = (2ki kp)1/2, (4) at long times the effective first-order rate constant drops to ki, and (5) the overall activation energy for the growth kinetics is the mean of the activation energies for the initiation and propagation steps. Monte Carlo simulations of the mechanism produce qualitatively similar kinetic plots, but the mean random walk length (and effective rate constant) is overestimated by the mean field approximation and when kp >> ki, we find k approximately ki0.7kp0.3 and Ea = (0.7Ei+ 0.3Ep). However the most striking prediction of the Monte Carlo simulations is that at long times, t >> 1/k, the effective first-order rate constant decreases to ki even in the absence of a chemical termination step. Experimental kinetic data for the reaction of undec-1-ene with hydrogen-terminated porous silicon under thermal reflux in toluene and ethylbenzene gave a value of k = 0.06 min(-1) and an activation energy of 107 kJ mol(-1). The activation energy is in reasonable agreement with density functional calculations of the transition state energies for the initiation and propagation steps.

Erythromycin as a prokinetic agent in preterm neonates: a systematic review.

BACKGROUND: It often takes several days or even weeks to establish full enteral feeds (FEFs) in preterm, especially extremely low birthweight neonates because of feed intolerance related to gastrointestinal hypomotility. Clinical trials of erythromycin as a prokinetic agent in preterm neonates have reported conflicting results. AIM: To systematically review the efficacy and safety of erythromycin as a prokinetic agent in preterm neonates. METHODS: Only randomised controlled trials in preterm neonates (gestation < or = 37 weeks) were considered eligible for inclusion. The primary outcome was the time to reach FEFs of 150 ml/kg/day. The secondary outcomes included the incidence of erythromycin related adverse effects such as diarrhoea, cardiac arrhythmias, and hypertrophic pyloric stenosis. No restrictions were applied on the dose (low: 3-12 mg/kg/day; antimicrobial: > or = 12 mg/kg/6-8 hours) and route (oral or intravenous) and mode (prophylactic or rescue) of administration. The standard methodology for systematic reviews was followed. A subgroup analysis was pre-planned based on the dose and mode of drug administration. RESULTS: Seven trials (three prophylaxis, four rescue) with various doses, routes and modes of administration, and durations of erythromycin treatment and different results were found to be eligible for inclusion in the analysis. Meta-analysis could not be performed, as specific data were either inadequate or not available. CONCLUSION: The conflicting trial results may be explained by differences in dose and route and mode of administration of erythromycin and in gastrointestinal motor responses in the presence of different feeding conditions-for example, fasting v fed state, intermittent v continuous feeds. Gestational and postnatal ages during erythromycin treatment are also important.

Impact of standardised feeding regimens on incidence of neonatal necrotising enterocolitis: a systematic review and meta-analysis of observational studies.

BACKGROUND: A significant and prolonged decline in the incidence of necrotising enterocolitis (NEC), nearing virtual elimination in some centres, has been observed consistently since implementation of a standardised feeding regimen. AIM: To systematically review the observational studies reporting incidence of NEC in preterm, low birth weight (LBW) neonates "before" and "after" implementation of a standardised feeding regimen. METHODS: The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 4, 2002), Medline, Embase, Cinahl, and proceedings of the Pediatric Academic Societies (published in Pediatric Research from 1980) were searched in July and again in October 2003. The reference lists of identified observational studies, and personal files, were searched. No language restriction was applied. Key words were: standardised, enteral, feeding, neonates, necrotising enterocolitis. Authors were contacted for clarification of data. RESULTS: Six eligible studies (1978-2003) were identified. A significant heterogeneity was noted between the studies indicating the variations in the population characteristics and feeding practices over a period of 25 years. Meta-analysis of the six studies using a random effects model revealed a pooled risk ratio of 0.13 (95% confidence interval 0.03 to 0.50)-that is, introduction of a standardised feeding regimen reduced the incidence of NEC by 87%. CONCLUSION: Standardised feeding regimens may provide the single most important global tool to prevent/minimise NEC in preterm neonates. Randomised controlled trials are needed.

Is surgical ligation of patent ductus arteriosus necessary? The Western Australian experience of conservative management.

BACKGROUND: Surgical ligation of patent ductus arteriosus (PDA) is widely practised in preterm infants despite no clear evidence that this improves outcomes. Geographical isolation meant that ductal ligation was not an option in King Edward Memorial Hospital until recently. OBJECTIVE: A retrospective data analysis to test the hypothesis that outcomes of infants with persistent PDA were no worse than those of infants with no significant duct or a duct that closed after medical treatment. PATIENTS AND METHODS: A total of 252 infants (gestation < or =28 weeks) born between 1 January 2000 and 30 June 2002 were divided into three groups: group 1, no significant PDA (n = 154); group 2, significant PDA which closed after medical treatment (n = 65); group 3, significant PDA remaining patent after medical treatment (n = 33). A significant PDA was defined by a left atrium to aortic root ratio of >1.4 or a ductal diameter >1.5 mm with a left to right shunt. RESULTS: Twenty four (10%) infants died at median (interquartile range) 15.5 (9-35) days. After adjustment for gestational age, relative to group 1, the infants from group 3 were at a 4.02 times increased risk of death (95% confidence interval 1.12 to 14.51). There was no significant difference between groups in the incidence of chronic lung disease, chronic lung disease or death, necrotising enterocolitis, intraventricular haemorrhage, duration of oxygen, or hospital stay. CONCLUSION: Mortality was higher in infants with a persistent PDA, but other morbidities were not significantly different. A randomised trial is needed to determine whether surgical ligation will reduce mortality in such infants.

Optimising enteral nutrition in growth restricted extremely preterm neonates--a difficult proposition.

BACKGROUND: Optimising enteral nutrition of extremely preterm neonates (EP: Gestation <28 weeks) with intrauterine growth restriction (IUGR) has always been difficult considering their higher risk of necrotising enterocolitis (NEC), and frequency of feed intolerance. AIM: To evaluate the nutritional outcomes in EP neonates with IUGR. METHODS: Data on demographic characteristics, feeding details (e.g. type of milk, postnatal age at start), and outcomes to discharge or death were collected from the medical notes for all EP neonates, who survived first 72 h of life, between January 2009 and December 2010. A standardised feeding protocol was followed during the study period. RESULTS: 38/220 (17.3%) EP neonates admitted during the study period had IUGR. The mean (IQR) age at start of minimal enteral nutrition [7 (5-10) versus 5 (4-8) days, p = 0.005), and nutritional (1 ml/2 hourly) feeds [12 (8-15) versus 9 (7-13) days, p = 0.034] was significantly delayed in IUGR compared to non-IUGR neonates. IUGR neonates reached full enteral feeds (150 ml/kg/day) at a significantly late median (IQR) postnatal age [32 (21-40) versus 24 (17-31) days, p = 0.009), taking longer time to achieve this milestone [20 (15-34) versus 16 (12-4) days, p = 0.008). The incidence of postnatal growth restriction was significantly higher in IUGR versus non-IUGR (73% versus 45%, p = 0.003) neonates. The incidence of ≥ Stage II NEC was low [18/220 (8.1%)] to make valid statistical comparisons. CONCLUSION: Optimising enteral nutrition in growth restricted extremely preterm neonates is difficult using the current strategies for enteral nutrition.

An in vitro study of the efficacy of rifampicin and minocycline coated umbilical venous catheters.

The use of antibiotic coated catheters has been proposed as a means of reducing catheter related sepsis. In this study, an in vitro comparison of bacterial colonisation rates was made between uncoated umbilical venous catheters and catheters coated with rifampicin and minocycline. The following parameters were determined; the direct antimicrobial effect of coated and uncoated catheter segments against a range of organisms associated with line sepsis, the assessment of the decline in antimicrobial activity in coated catheters immersed in plasma and the inhibitory efficacy of the catheters to colonisation over a 28-day period. Minocycline and rifampicin coated umbilical catheters showed a superior inhibitory effect and prevented colonisation with the commoner line-related organisms, when compared with uncoated catheters. The inhibitory effect declined after 14 days in the human plasma. Resistance to colonisation in vitro may not extend beyond 21 days.

Phosphodiesterase inhibitors for persistent pulmonary hypertension of the newborn: a review.

Persistent pulmonary hypertension of the newborn (PPHN) is a complex syndrome with multiple causes, with an incidence of 0.43-6.8/1,000 live births and a mortality of 10-20%. Survivors have high morbidity in the forms of neurodevelopmental and audiological impairment, cognitive delays, hearing loss, and a high rate of rehospitalization. The optimal approach to the management of PPHN remains controversial. Inhaled nitric oxide (iNO) is currently regarded as the gold standard therapy, but with as many as 30% of cases failing to respond, has not proven to be the single magic bullet. Given the complex pathophysiology of the disease, any such magic bullet is unlikely. A number of recent studies have suggested a role for specific phosphodiesterase (PDE) inhibitors in the management of PPHN. Sildenafil, a specific PDE5 inhibitor, appears the most promising of such agents. We aim to review the current status and limitations of iNO and the potential of PDE inhibitors in the management of PPHN. The reasons why caution is warranted before specific PDE5 inhibitors like sildenafil are labelled as potential magic bullets for PPHN will be discussed. The need for randomized-controlled trials to determine the safety, efficacy, and long-term outcome following treatment with sildenafil in PPHN is emphasized.