1,721,009 research outputs found
A nutritional program to improve outcome of very low birth weight infants
No full textBackground & aims: The growth of very low birth weight infants does not match intrauterine trajectories, likely due to inappropriate caloric intake. We therefore investigated whether modification of the standard nutritional schedule can impact postnatal growth. Methods: We introduced a set of evidence-based strategies in a study group of infants (n = 123): 1) higher maximum intake of intravenous amino acids and lipids; 2) prioritisation of earlier enteral feeding; 3) faster attainment of full enteral feeds; 4) daily adjustment of enteral feeds according to growth trajectory; and 5) utilisation of an electronic pre-structured prescription ordering system that tracks individual growth and energy intake. These infants were compared with a control group (n = 115) in a pre/post retrospective cohort study. Results: The study group achieved a higher caloric intake, attained full enteral feeds 5 days earlier, and returned to their birth weight more rapidly than the control group. At 36 weeks postmenstrual age, infants who had been born at <30 weeks were heavier (6,260 g) but had a similar percentage fat mass. Those born at <28 weeks had a larger head circumference (Delta 1.4 cm) and lower sepsis rate (7.8%). Conclusions: Optimization of early postnatal nutrition and daily adjustment of milk intake according to weight gain improved growth, without any unfavourable outcomes for body composition and neuro-developmental follow-up. (C) 2011 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved
IDENTIFYING FACTORS DRIVING TNF-α EXPRESSION IN THE DUAL CLOSED LOOP EX-VIVO PLACENTAL PERFUSION MODEL: A METHODOLOGICAL STUDY
Full text linkThe pathophysiology of how a maternal infection induces fetal inflammation and subsequently premature birth is a growing area of research. The ex-vivo dual closed-loop placental perfusion model has been widely used to study placental physiology. To address the association between bacterial chorioamnionitis and fetal inflammation, TNF-α induction following lipopolysaccharide (LPS) challenge – a pyrogen of Gram-negative origin – was measured in the perfusion model. Preliminary analysis of perfusates unexpectedly revealed markedly elevated levels of TNF-α in control and LPS-treated groups indicating contamination of material(s) capable of activating innate immune responses. To identify source(s) driving high background TNF-α expression in perfusates, bovine serum albumin (BSA) – the chief component of the perfusion media – the perfusion system and the materno-feto-placental unit were independently examined. To validate a cleaning protocol effective in LPS removal, acid-base and oxidative depyrogenation techniques were also additionally assessed in the perfusion system. Using TNF-α as a surrogate marker of contamination, high background TNF-α expression in previously conducted placental perfusions were attributed to (1) LPS contaminated perfusion media and (2) LPS build up in the perfusion system. Additionally, results from depyrogenation experiments revealed both acid-base and oxidative techniques effectively reduced LPS buildup in the perfusion system to levels that were in accordance with FDA guidelines for medical equipment (Master of Science (MSc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Characterizing Gas Exchange and Assessing Feasibility of a New Lung Assist Device for Pre-Term and Term Neonates with Respiratory Distress Failure
No full textRespiratory distress syndrome is a major cause of mortality among pre-term and term neonatal population. To overcome the limitations of current therapies, a new form of respiratory support termed the, “Artificial Placenta” has been proposed. The Artificial Placenta is a type of oxygenator that is attached postnatally via the umbilical vessels to provide pumpless respiratory support to pre-term and term neonates. To develop this concept, our group previously reported on a novel polycarbonate membrane lung assist device (LAD). To build upon its development, the objectives of this thesis are to determine the optimal interface for gas exchange, and characterize the gas exchange properties of the LAD under ambient and oxygen rich atmosphere. Subsequently, its feasibility was determined by studying the effects of extracorporeal flow rates on cardiovascular parameters and gas exchange performance was assessed in a newborn piglet model. In vitro testing demonstrated that PDMS based membrane is the optimal interface for gas exchange in the LAD. In vitro testing of the LAD demonstrated 2.4 µL/min/cm² -3.8 µL/min/cm² and 6.4 µL/min/cm²- 10.1 µL/min/cm² of O2 and CO2 transfer respectively under ambient air and oxygen rich atmospheric conditions. Based on these results, the LAD theoretically could provide 6-11% of metabolic O2 while eliminating 18-26% of CO2 in a newborn healthy pre term infant. Experiments in newborn piglet models achieved pumpless configuration with flow rates up to 60.9ml/kg/min without presenting decompensation. Preliminary, in vivo gas exchange experiments demonstrated O2 transfer of 3ul/min/cm2, which matches closely to in vitro data. A novel pumpless LAD is reported, which provides sufficient respiratory support. High extracorporeal flow rates with stable cardiovascular parameters demonstrate feasibility of the artificial placenta concept. This novel LAD could potentially serve as a rescue device when all other therapies such as nasal continuous positive airway and mechanical ventilation fail.Master of Applied Science (MASc
FATTY ACID PROFILES OF NUTRTION SOURCES AND PLASMA IN PRETERM INFANTS
Full text linkPreterm infants are not able to tolerate full enteral feeding of breast milk due to gut immaturity. To fill this nutritional gap, parenteral nutrition is introduced while enteral feeding is gradually increased. Of parenteral nutrition, lipid emulsions supply energy, essential and polyunsaturated fatty acids, which significantly affect short- and long-term health outcomes of growth, visual-and neuro-development for preterm infants. However, elevated plasma triglyceride (TG) levels in preterm infants receiving lipid emulsions have been observed despite less lipid intake compared to breast milk fed infants. We hypothesized that unbalanced fatty acid profiles in lipid emulsion was one factor to cause high plasma TGs for preterm infants. In the multi-center, observational, prospective study, the following samples were analyzed using GC-MS: (1) lipid emulsions (n=5) and breast milk (n=112), (2) plasma (n=294) including normal TG (n=116) and high TG (n=88). Lipoproteins in normal TG (n=18) and high TG (n=24) plasma were measured using gel electrophoresis. Fatty acid profiles in lipid emulsions differed from ones in breast milk. Plasma fatty acid profiles were related to dietary fatty acid intake. Accumulation of all fatty acids except C20:5n3 and relatively high (LDL+VLDL) levels (p<0.001) resulted in high TG plasma compared to normal TG plasma. Overall, this study supports the hypothesis that nutrition of lipid emulsions was associated high TG with differences in fatty acid uptake but it is still unclear if the imbalance of fatty acids directly causes high TG. More research is necessary to investigate other factors such as enzyme activity, lipid clearance rate, or different rate of fatty acid metabolism.ThesisMaster of Science (MSc
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
INDIVIDUAL REFERENCE GROWTH TRAJECTORIES FOR PRETERM INFANTS WITH POSTNATAL WEIGHT LOSS AND CONVERGENCE WITH TERM TRAJECTORIES OPTIMIZED TO MINIMIZE DISEASE RISK (DOHAD) - IMPLICATIONS FOR CALCULATION OF POSTNATAL GROWTH RATES IN CLINICAL PRACTICE
Full text linkBACKGROUND: The DoHAD hypothesis suggests that preterm infants should achieve similar growth and body composition to healthy term-born infants in order to minimize disease risk. Postnatal growth of preterm infants is not fully understood and requires additional characterization, particularly in terms of differences to and transition from intrauterine growth. The period of postnatal adaptation to extrauterine life has been described in preterm infants by Rochow et al., 2016 and was seen to last 21 days. During these first 21 days of life, preterm infants experience a physiological, one-time, permanent contraction of extracellular water spaces (water loss), which causes a downward shift in the growth trajectories. This period of adaptation/water loss and the transition to extrauterine growth rates to achieve WHOGS target trajectories need to be incorporated into individual reference curves for preterm infants.
OBJECTIVES: To develop and evaluate approaches to establish individualized growth trajectories for preterm infants to achieve growth similar to the WHO growth standards (WHOGS) for healthy infants at term, using recently published data about the physiological postnatal adaptation.
METHODS: Two approaches were compared: 1) Postnatal-Percentile Approach: growth following the percentile at day of life (DOL) 21 until term; 2) Growth-Velocity Approach: using day-specific Fenton median growth velocities between DOL 21 and term. The impact of these approaches were compared using body compositions of 57 healthy preterm infants obtained before discharge (36+0/7 to 42+6/7 weeks PMA).
The main outcome was the weight difference between the predicted trajectory and WHOGS target at 42+0/7 weeks PMA for the infants’ birth weight percentile.
RESULTS: Postnatal-Percentile Approach: Trajectories deviated by up to 930g and did not match with WHOGS. Growth-Velocity Approach: Trajectories converged with term WHOGS after adjusting growth velocities with a factor of 1.0017 (approximately 10% increase in daily growth velocities). The validation of the Growth-Velocity Approach in preterm infants with minimal medical interventions revealed little deviation between predicted and actual weights. Infants were symmetrically distributed around zero deviation with a mean deviation of -10±370g and an average of 20% fat mass. In contrast, the Postnatal-Percentile Approach showed large deviations between predicted and actual weights and a skewed distribution around zero deviation with a mean deviation of -310±380g or 70±350g, following the birth or DOL 21 percentile, respectively.
CONCLUSIONS: Individualized growth trajectories for preterm infants converged with the WHOGS when Fenton daily median growth velocities were applied and optimized with a single factor. The simplicity of the model and its ability to predict target weights that correspond to an appropriate fat mass suggests a biological principle. These results provide a superior understanding of preterm infant’s growth including the physiological postnatal adaptation and new trajectories to achieve WHOGS target trajectories. Results can be used to develop a bedside tool to aid clinicians in monitoring growth, guiding nutrition and preventing chronic adult diseases as a consequence of unguided, inappropriate growth.ThesisMaster of Science (MSc)It has been well established that growth of preterm infants has a long-term impact on health in adulthood. Since the survivability of preterm infants has drastically improved in the last decades, there has been a shift in focus to improving quality of life, including improved growth. Infants that grow too quickly or too slowly may develop inappropriate body compositions, with either too much or too little fat. A sub-optimal body composition can put infants at an increased risk for developing cardiovascular, metabolic or neurodevelopmental diseases later in life. In order to prevent these diseases and optimize growth, it is necessary to have a better understanding of how preterm infants should grow. This thesis aims to improve the characterization of growth for preterm infants by providing individual reference growth trajectories for preterm infants that take into consideration postnatal adaptation and aim to minimize later disease risk
TARGET FORTIFICATION FOR PRETERM INFANTS
Full text linkBackground: Breast milk is an ideal source of nutrition for newborns as it provides nutrients required for growth in addition to numerous bioactive factors which help to develop an infant’s immune system. However, the macronutrient content of breast milk alone is not able to support preterm infant’s rapid growth needs and requires supplementation with fortifiers. There is strong evidence that the current practice of standard fortification (SF) may lead to nutritional deficits and consequently increases an infant’s risk of inadequate postnatal growth. Furthermore, the natural variation of breast milk composition makes it increasingly difficult to provide recommended macronutrient intakes with the SF. Individualized approaches, like adjustable fortification or target fortification (TFO), have been proposed to improve growth during hospitalization. A recent pilot trial demonstrated that TFO, which individually adjusts deficient macronutrient content after SF by analyzing the breast milk for native protein, carbohydrate and fat, is feasible in clinical practice and significantly reduces variation of macronutrient intakes.
Objectives: To compare the response of preterm infants to feedings of breast milk with either SF or SF+TFO with respect to: 1) weight at 36 weeks’ post-menstrual age and growth velocity during hospitalization; 2) head circumference, length and body composition; and 3) the relationship between preterm infant’s weight or growth velocity and their macronutrient intake factors including protein intake and protein:energy (P:E) ratio.
Methods: This was a single-center, double-blind randomized controlled trial completed at McMaster Children’s Hospital’s Level III NICU with a study period of at least 21 days. Preterm infants (n=103) born at <30 weeks of gestation and tolerating full enteral intakes of breast milk were enrolled and randomized to the Control (SF only) or Intervention (SF+TFO) groups. Native breast milk samples were collected for all infants on each study day and were analyzed for protein, carbohydrate and fat content. In the Control group, SF was provided using Enfamil (Mead Johnson, IL) human milk fortifier at the recommended dosage. In the Intervention group, after the addition of SF, modular macronutrient fortifiers were added based on analysis of the mother’s milk to reach target values based on ESPGHAN recommendations. Adjustment of the modular fortifiers was done three times per week. The primary outcomes were weight at 36 weeks’ PMA and growth velocity during the study period. Head circumference, length and body composition were also assessed at term-equivalent age. Subgroup analysis, stratified around the median protein levels after SF, also compared the growth outcomes between Control and Intervention groups. Multiple regression analysis models examined the effect of macronutrient intake factors and infant characteristics on weight, average growth velocity and daily weight gain.
Results: Infants fed with SF+TFO had significantly higher protein (p<0.001), carbohydrate (p<0.001) and fat intakes (p<0.01) in addition to higher protein:energy and carbohydrate:non-protein energy (CHO:NPE) ratios (p<0.001) compared to those fed with SF alone. The average weight at 36 weeks’ PMA and growth velocity during the 21-day study period were higher for infants in the Intervention group (p<0.001). The Intervention group had significantly higher fat-mass (p<0.05) as well as more fat-free mass than the Control group at term-equivalent age (TEA), but were still within normal limits when compared to normative data from our NICU. At TEA, infants fed with TFO also showed significantly higher change in z-scores from birth for length when compared to infants fed SF with low-protein intakes (p<0.05). Change in head circumference z-scores were not statistically significant between groups. Higher average protein intakes and P:E ratios were each positively associated with higher weight at 36 weeks’ PMA (p<0.05). Moreover, higher daily weight gain was positively associated with higher daily protein intake from the previous study day (p<0.05). The absolute difference in day-to-day macronutrient intakes, however, were not significant predictors of daily weight gain.
Conclusions: This study shows that target fortification of breast milk is promising as an individualized approach to improve the quality of nutrition for preterm infants. By addressing the variation and deficits of macronutrients that occur after standard fortification, infants were able to achieve higher body weight and faster weight gain. In the short term, target fortification may reduce the preterm infant’s risk for sub-optimal postnatal growth. These improved growth outcomes also have positive clinical implications on infant’s long-term health and development. Protein intake and the P:E ratio were identified as important factors for growth and should be considered in nutritional management and future fortification strategies for breast milk fed preterm infants.ThesisMaster of Science (MSc
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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