RESUMEN

An important challenge for modelling transport in materials for energy applications is that in most applications they are polycrystalline, and hence it is critical to understand the properties in the presence of grain boundaries. Moreover, most grain boundaries are not pristine stoichiometric interfaces and hence dopants are likely to play a significant role. In this paper, we describe our recent work on using atomistic molecular dynamics simulations to model the effect of doped grain boundaries on oxygen transport of fluorite structured UO2. UO2, much like other fluorite grain boundaries, are found to be sinks for oxygen vacancy segregation relative to the grain interior, thus facilitating oxygen transport. Fission products further enhance diffusivity via strong interactions between the impurities and oxygen defects. Doping produces a striking structural alteration in the Σ5 class of grain boundaries that enhances oxygen diffusivity even further. This article is part of a discussion meeting issue 'Energy materials for a low carbon future'.

RESUMEN

OBJECTIVE: Our objective was to evaluate the impact of a dedicated resuscitation and stabilization (RAS) room and process changes on infant stabilization time. STUDY DESIGN: A prospective quality improvement study was conducted on preterm infants in a tertiary care center. A dedicated RAS room, preresuscitation huddle, infant-isolette-ventilator pairing and improved documentation were implemented. The primary outcome was median time to stabilization and secondary outcomes were illness severity on day 1 and morbidity at discharge. RESULTS: A sustained reduction in median time to stabilization from 90 min in the preimplementation phase to 72 min in the sustainability phase was observed. All planned and iterative process changes were integrated into the RAS team's daily routine. Time to completion of procedures decreased, illness severity and morbidity remained unchanged. CONCLUSION: A dedicated RAS room adjacent to the delivery suite in conjunction with process changes improves efficiency of care.

Asunto(s)

RESUMEN

This paper describes how a relatively new style of online learning, a massive open online course (MOOC), may be used to raise aspirations and widen participation in dental professions. A MOOC was designed and run with the aim of engaging prospective students of dental professions in learning and discussion. Over 4,200 learners signed up, and 450 students fully completed this first run of the course. The course attracted a significantly younger demographic than is typical for MOOCs, and nearly a third who responded to the pre-course survey reported they were doing the course specifically as preparation for a dental degree. The approach also provided a platform for public engagement on the subject of dentistry with participants, both dental professionals and members of the public, contributing to discussion around the learning materials from around the world, providing a unique, internationalised perspective of oral healthcare for learners. This study shows that there is genuine potential for MOOCs to involve people from disadvantaged backgrounds in higher education by offering free, accessible, enjoyable and engaging educational experiences. The data gives us cautious optimism that these courses can play a significant role within a platform of other WP interventions.

Asunto(s)

RESUMEN

To better define the mechanisms by which condensed-phase halides may be oxidized to form gas-phase halogens under polar conditions, experiments have been conducted whereby frozen solutions containing chloride (1 M), bromide (1.6 x 10(-3) to 5 x 10(-2) M), iodide (<1 x 10(-5) M), and nitrate (0.01 to 1 M) have been illuminated by ultraviolet light in a continually flushed cell. Gas-phase products are quantified using chemical ionization mass spectrometry, and experiments were conducted at both 248 and 263 K. Br(2) was the dominant product, along with smaller yields of IBr and trace BrCl and I(2). The Br(2) yields were largely independent of the Br(-)/Cl(-) ratio of the frozen solution, down to seawater composition. However, the yields of halogens were strongly dependent on the levels of NO(3)(-) and acidity in solution, consistent with a mechanism whereby NO(3)(-) photolysis yields OH that oxidizes the condensed-phase halides. In support, we observed the formation of gas-phase NO(2), formed simultaneously with OH. Gas-phase HONO was also observed, suggesting that halide oxidation by HONO in the condensed phase may also occur to some degree. By measuring the production rate of condensed-phase OH, using benzoic acid as a radical trap, we determine that the molar yield of Br(2) formation relative to OH generation is 0.6, consistent with each OH being involved in halide oxidation. These studies suggest that gas-phase halogen formation should occur simultaneously with NO(x) release from frozen sea ice and snow surfaces that contain sufficient halides and deposited nitrate.

Asunto(s)

RESUMEN

BACKGROUND: Preterm infants experience a range of morbidity related to the immaturity of their organ systems and to concurrent disease states. There is concern that an unfavourable environment in the neonatal intensive care unit (NICU) may compound this morbidity. Modification of the environment could minimize the iatrogenic effects. Developmental care is a broad category of interventions designed to minimize the stress of the NICU environment. These interventions may include elements such as control of external stimuli (vestibular, auditory, visual, tactile), clustering of nursery care activities, and positioning or swaddling of the preterm infant. Individual strategies have also been combined to form programs, such as the 'Newborn Individualized Developmental Care and Assessment Program' (NIDCAP) (Als 1986). OBJECTIVES: In preterm infants, do developmental care interventions reduce neurodevelopmental delay, poor weight gain, length of hospital stay, length of mechanical ventilation, physiological stress and other clinically relevant adverse outcomes? SEARCH STRATEGY: The Neonatal Review Group search strategy was utilized. Searches were made of MEDLINE from 1966 to June, 2005 and of CINAHL, The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005), and conference and symposia proceedings in the English language from 1990 to June, 2005. A search of EMBASE was also made from 2003 to June 2005. A list of all relevant articles was sent to two experts in the field to identify any omissions or additional unpublished studies. SELECTION CRITERIA: Randomized trials in which elements of developmental care are compared to routine nursery care for infants < 37 weeks gestation and that measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted and all potentially relevant titles and abstracts were extracted. Retrieved articles were assessed for relevance independently by two reviewers, based on predetermined criteria. Articles that met all criteria for relevance were assessed for methodological quality based on predetermined criteria. Articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. Meta-analyses were conducted for each intervention where the same outcome measures and/or instruments were used within comparable time points. MAIN RESULTS: This review detected 36 eligible randomized controlled trials involving four major groups of developmental care interventions, 19 sub-groups and multiple clinical outcomes. In addition, the long-term outcomes of a previously included trial were added to the review. The results of the review indicate that developmental care interventions demonstrate limited benefit to preterm infants with respect to: decreased moderate-severe chronic lung disease, decreased incidence of necrotizing enterocolitis and improved family outcome. Conversely, an increase in mild lung disease and an increase in the length of stay were demonstrated in infants receiving developmental care compared to controls. There is also very limited evidence of the long-term positive effect of NIDCAP on behavior and movement at 5 years corrected age but no effect on cognition. Other individualized developmental care interventions have also demonstrated some effect in enhancing neurodevelopmental outcome. Although a limited number of other benefits were demonstrated, those results were from single studies with small sample sizes. The lack of blinding of the assessors was a significant methodological flaw in half of the studies. The cost of the interventions and personnel was not considered in any of the studies. AUTHORS' CONCLUSIONS: Because of the inclusion of multiple interventions in most studies, the determination of the effect of any single intervention is difficult. Although there is evidence of limited benefit of developmental care interventions overall, and no major harmful effects reported, there were a large number of outcomes for which no or conflicting effects were demonstrated. The single trials that did show a significant effect of an intervention on a major clinical outcome were based on small sample sizes, and the findings were often not supported in other small trials. Before a clear direction for practice can be supported, evidence demonstrating more consistent effects of developmental care interventions on important short- and long-term clinical outcomes is needed. The economic impact of the implementation and maintenance of developmental care practices should be considered by individual institutions.

Asunto(s)

RESUMEN

BACKGROUND: Non-nutritive sucking is used during gavage feeding and in the transition from gavage to breast/bottle feeding in preterm infants. The rationale for this intervention is that non-nutritive sucking facilitates the development of sucking behaviour and improves digestion of enteral feedings. Non-nutritive sucking has been considered to be a benign intervention, although it has the potential to have a negative effect on breastfeeding or on the incidence of later oral aversion. OBJECTIVES: To determine whether non-nutritive sucking (NNS) in preterm infants influences: a) weight gain, b) energy intake, c) heart rate, d) oxygen saturation, e) length of hospital stay, f) intestinal transit time, g) age at full oral feeds, or h) any other clinically relevant outcomes. SEARCH STRATEGY: MEDLINE and CINAHL databases back to 1976 and The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2005) were searched. The EMBASE database was added to the search strategy for 2005. Reference lists/bibliographies of relevant articles and reviews were also searched. A comprehensive list of relevant articles was sent to two major authors in this area. They were asked if they knew of any other published or unpublished studies relevant to the area that had not been included in the original list. SELECTION CRITERIA: All trials utilizing experimental or quasi-experimental designs in which non-nutritive sucking in preterm infants was compared to no provision of non-nutritive sucking. Measured clinically relevant outcomes. Reports were in English or a language for which a translator was available.Computerized searches were conducted by both reviewers. All potentially relevant titles and abstracts identified by either reviewer were extracted. All retrieved articles were assessed for relevance independently by each reviewer, based on a pre-determined set of criteria. The reference lists/bibliographies of each article were reviewed independently for additional relevant titles and were also retrieved and assessed for relevance. Articles that met all relevance criteria were then assessed for methodologic quality based on a predetermined set of criteria. Those articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. No subgroup analyses were performed because of the small number of studies related to the relevant outcomes. MAIN RESULTS: This review consisted of 21 studies, 15 of which were randomized controlled trials. NNS was found to decrease significantly the length of hospital stay in preterm infants. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, age at full oral feeds and behavioral state). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds and better bottle feeding performance. No negative outcomes were reported in any of the studies. AUTHORS' CONCLUSIONS: This review found a significant decrease in length of stay in preterm infants receiving a NNS intervention. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, age at full oral feeds and behavioral state). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds and better bottle feeding performance. No negative outcomes were reported in any of the studies. There were also a number of limitations of the presently available evidence related to the design of the studies, outcome variability, and lack of long-term data. Based on the available evidence, NNS in preterm infants would appear to have some clinical benefit. It does not appear to have any short-term negative effects. In view of the fact that there are no long-term data, further investigations are recommended. In order to facilitate meta-analysis of these data, future research in this area should involve outcome measures consistent with those used in previous studies. In addition, published reports should include all relevant data.

Asunto(s)

RESUMEN

A standard dose of 500 IU of eCG is commonly given to progestogen pre-treated anestrous ewes for induction of estrus. Twelve seasonally anestrous and 12 cyclic Western White Face ewes were treated for 12 days with intravaginal sponges impregnated with medroxyprogesterone acetate (MAP). In trials in both the breeding and nonbreeding seasons, six randomly selected ewes were given 500 IU of eCG at sponge removal to determine the effects of low dose of eCG on ovarian antral follicular dynamics and ovulation. Ultrasound scanning and blood sampling were done daily. Treatment with eCG did not have marked effects on antral follicular growth. All ewes ovulated, except for five of six control anestrous ewes. Luteal structures and progesterone secretion were confirmed in all but the control anestrous ewes. In the breeding season, peak progesterone concentrations were greater (P<0.05) in eCG-treated compared to control ewes. Daily serum estradiol concentrations were greater in the periovulatory period in eCG-treated compared to control ewes (treatment-by-day interaction; P<0.05), particularly in anestrus. Progestogen-treated ewes ovulated follicles from several follicular waves, in contrast to ovulations of follicles from the final wave of the cycle in untreated, cyclic ewes. Anestrous ewes exhibited more frequent follicular waves and FSH peaks compared to cyclic ewes after a progestogen/eCG treatment. In conclusion, 500 IU of eCG given after 12 days of progestogen treatment had limited effects on the dynamics of ovarian follicular waves. However, eCG treatment increased serum concentrations of estradiol during the periovulatory period, particularly in anestrous ewes; this probably resulted in the synchronous estrus and ovulation in anestrous ewes.

Asunto(s)

RESUMEN

BACKGROUND: Preterm infants experience a range of morbidity related to the immaturity of their organ systems and to concurrent disease states. An unfavourable environment in the neonatal intensive care unit (NICU) may compound this morbidity. Modification of the environment could minimize the iatrogenic effects. Developmental care is a broad category of interventions designed to minimize the stress of the NICU environment. These interventions may include one or more elements such as control of external stimuli (vestibular, auditory, visual, tactile), clustering of nursery care activities, and positioning or swaddling of the preterm infant. Individual strategies have also been combined to form programs, such as the 'Neonatal Individualized Developmental Care and Assessment Program' (NIDCAP) (Als 1986). OBJECTIVES: In preterm infants, do developmental care interventions reduce neurodevelopmental delay, poor weight gain, length of hospital stay, length of mechanical ventilation, physiological stress and other clinically relevant adverse outcomes? SEARCH STRATEGY: The Neonatal Review Group search strategy was utilized. Searches were made of MEDLINE from 1966 to July, 2003, and of CINAHL, The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2003), and conference and symposia proceedings in the English language from 1990 to July, 2003. A list of all relevant articles was sent to two experts in the field to identify any omissions or additional unpublished studies. SELECTION CRITERIA: Randomized trials in which elements of developmental care are compared to routine nursery care for infants < 37 weeks gestation and that measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted and all potentially relevant titles and abstracts were extracted. Retrieved articles were assessed for relevance independently by two reviewers, based on predetermined criteria. Articles that met all criteria for relevance were assessed for methodological quality based on predetermined criteria. Articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. Meta-analyses were conducted for each intervention where the same outcome measures and/or instruments were used within comparable time points. MAIN RESULTS: This review detected 32 eligible randomized controlled trials involving four major groups of developmental care interventions, 19 sub-groups and multiple clinical outcomes. The results of the review indicate that developmental care interventions demonstrate some benefit to preterm infants with respect to: improved short-term growth and feeding outcomes, decreased respiratory support, decreased length and cost of hospital stay, and improved neurodevelopmental outcomes to 24 months corrected age. These findings were based on two or three small trials for each outcome, and did not involve meta-analyses of more than two trials for any one outcome. Although a number of other benefits were demonstrated, those results were from single studies with small sample sizes. The lack of blinding of the assessors was a significant methodological flaw in half of the studies. The cost of the interventions and personnel was not considered in any of the studies. REVIEWER'S CONCLUSIONS: Because of the inclusion of multiple interventions in most studies, the determination of the effect of any single intervention is difficult. Although there is evidence of some benefit of developmental care interventions overall, and no major harmful effects reported, there were a large number of outcomes for which no or conflicting effects were demonstrated. The single trials that did show a significant effect of an intervention on a major clinical outcome were based on small sample sizes, and the findings were often not supported in other small trials. Before a clear direction for practice can be supported, evidence demonstrating more consistent effects of developmental care interventions on important short- and long-term clinical outcomes is needed. The economic impact of the implementation and maintenance of developmental care practices should be considered by individual institutions.

Asunto(s)

RESUMEN

BACKGROUND: Non-nutritive sucking is used during gavage feeding and in the transition from gavage to breast/bottle feeding in preterm infants. The rationale for this intervention is that non-nutritive sucking facilitates the development of sucking behaviour and improves digestion of enteral feedings. Non-nutritive sucking has been considered to be a benign intervention, although it has the potential to have a negative effect on breastfeeding or on the incidence of later oral aversion. OBJECTIVES: To determine whether non-nutritive sucking (NNS) in preterm infants influences: a) weight gain, b) energy intake, c) heart rate, d) oxygen saturation, e) length of hospital stay, f) intestinal transit time, g) age at full oral feeds, or h) any other clinically relevant outcomes. SEARCH STRATEGY: MEDLINE and CINAHL databases back to 1976 and the Cochrane Controlled Trials register were searched. Reference lists/bibliographies of relevant articles and reviews were also searched. A comprehensive list of relevant articles was sent to two major authors in this area. They were asked if they knew of any other published or unpublished studies relevant to the area that had not been included in the original list. The searches of MEDLINE, CINAHL and CCTR were updated to December 2000. SELECTION CRITERIA: All trials utilizing experimental or quasi-experimental designs in which non-nutritive sucking in preterm infants was compared to no provision of non-nutritive sucking. Measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted by both reviewers. All potentially relevant titles and abstracts identified by either reviewer were extracted. All retrieved articles were assessed for relevance independently by each reviewer, based on a pre-determined set of criteria. The reference lists/bibliographies of each article were reviewed independently for additional relevant titles and were also retrieved and assessed for relevance. Articles that met all relevance criteria were then assessed for methodologic quality based on a predetermined set of criteria. Those articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. No subgroup analyses were performed because of the small number of studies related to the relevant outcomes. MAIN RESULTS: This review consisted of 20 studies, 14 of which were randomized controlled trials. NNS was found to decrease significantly the length of hospital stay in preterm infants. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, and age at full oral feeds). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds, better bottle feeding performance and behavior. No negative outcomes were reported in any of the studies. REVIEWER'S CONCLUSIONS: This review found a significant decrease in length of stay in preterm infants receiving a NNS intervention. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, and age at full oral feeds). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds, better bottle feeding performance and behavior. No negative outcomes were reported in any of the studies. There were also a number of limitations of the presently available evidence related to the design of the studies, outcome variability, and lack of long-term data. Based on the available evidence, NNS in preterm infants would appear to have some clinical benefit. It does not appear to have any short-term negative effects. In view of the fact that there are no long-term data, further investigations are recommended. In order to facilitate meta-analysis of these data, future research in this area should involve outcome measures consistent with those used in previous studies. In addition, published reports should include all relevant data.

Asunto(s)

RESUMEN

BACKGROUND: Preterm infants experience a range of morbidity related to the immaturity of their organ systems and to concurrent disease states. An unfavourable environment in the neonatal intensive care unit (NICU) may compound this morbidity. Modification of the environment could minimize the iatrogenic effects. Developmental care is a broad category of interventions designed to minimize the stress of the NICU environment. These interventions may include one or more elements such as control of external stimuli (vestibular, auditory, visual, tactile), clustering of nursery care activities, and positioning or swaddling of the preterm infant. Individual strategies have also been combined to form programs, such as the 'Neonatal Individualized Developmental Care and Assessment Program' (NIDCAP) (Als 1986). OBJECTIVES: In preterm infants, do developmental care interventions reduce neurodevelopmental delay, poor weight gain, length of hospital stay, length of mechanical ventilation, physiological stress and other clinically relevant adverse outcomes? SEARCH STRATEGY: The Neonatal Review Group search strategy was utilized. Searches were made of Medline from 1966 to July, 2000, and of CINAHL, The Cochrane Library, and conference and symposia proceedings in the English language from 1990 to July, 2000. A list of all relevant articles was sent to two experts in the field to identify any omissions or additional unpublished studies. SELECTION CRITERIA: Randomized trials in which elements of developmental care are compared to routine nursery care for infants < 37 weeks gestation and that measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted and all potentially relevant titles and abstracts were extracted. Retrieved articles were assessed for relevance independently by two reviewers, based on predetermined criteria. Articles that met all criteria for relevance were assessed for methodological quality based on predetermined criteria. Articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. Meta-analyses were conducted for each intervention where the same outcome measures and/or instruments were used within comparable time points. MAIN RESULTS: This review detected 31 eligible randomized controlled trials involving four major groups of developmental care interventions, 19 sub-groups and multiple clinical outcomes. The results of the review indicate that developmental care interventions demonstrate some benefit to preterm infants with respect to: improved short-term growth outcomes, decreased respiratory support, decreased length and cost of hospital stay, and improved neurodevelopmental outcomes to 24 months corrected age. These findings were based on two or three small trials for each outcome, and did not involve meta-analyses of more than two trials for any one outcome. Although a number of other benefits were demonstrated, those results were from single studies with small sample sizes. The lack of blinding of the assessors was a significant methodological flaw in half of the studies. The cost of the interventions and personnel was not considered in any of the studies. REVIEWER'S CONCLUSIONS: Because of the inclusion of multiple interventions in most studies, the determination of the effect of any single intervention is difficult. Although there is evidence of some benefit of developmental care interventions overall, and no major harmful effects reported, there were a large number of outcomes for which no or conflicting effects were demonstrated. The single trials that did show a significant effect of an intervention on a major clinical outcome were based on small sample sizes, and the findings were often not supported in other small trials. Before a clear direction for practice can be supported, evidence demonstrating more consistent effects of developmental care interventions on important short- and long-term clinical outcomes is needed. The economic impact of the implementation and maintenance of developmental care practices should be considered by individual institutions.

Asunto(s)

RESUMEN

Hypoxemia is a commonly observed complication during the chemical immobilization of wild ruminants. If severe and left untreated, it can predispose animals to arrhythmias, organ failure, and capture myopathy. The following prospective study was designed to measure the degree of hypoxemia in wapiti that were immobilized with a combination of xylazine and tiletamine-zolazepam and to assess the response to nasal oxygen therapy. Pulse oximetry and arterial blood gas analysis were used to assess the degree of hypoxemia prior to nasal insufflation of oxygen and to demonstrate any beneficial effects of this intervention. All wapiti exhibited mild to marked hypoxemia (PaO2 = 43 +/- 11.8 mmHg) prior to treatment and showed marked improvement after 5 minutes of nasal insufflation of oxygen at 10 L/min (PaO2 = 207 +/- 60 mmHg). This inexpensive, noninvasive technique has great benefit in treating clinical hypoxemia under field conditions, and we recommend that nasal insufflation of oxygen be implemented during xylazine-tiletamine-zolazepam-induced immobilization of wapiti and other wild ruminants.

Asunto(s)

RESUMEN

BACKGROUND: Preterm infants experience a range of morbidity related to the immaturity of their organ systems and to concurrent disease states. An unfavourable environment in the neonatal intensive care unit (NICU) may compound this morbidity. Modification of the environment could minimize the iatrogenic effects. Developmental care is a broad category of interventions designed to minimize the stress of the NICU environment. These interventions may include one or more elements such as control of external stimuli (vestibular, auditory, visual, tactile), clustering of nursery care activities, and positioning or swaddling of the preterm infant. Individual strategies have also been combined to form programs, such as the 'Neonatal Individualized Developmental Care and Assessment Program' (NIDCAP) (Als 1986). OBJECTIVES: In preterm infants, do developmental care interventions reduce neurodevelopmental delay, poor weight gain, length of hospital stay, length of mechanical ventilation, physiological stress and other clinically relevant adverse outcomes? SEARCH STRATEGY: The Neonatal Review Group search strategy was utilized. Searches were made of Medline from 1966 to July, 2000, and of CINAHL, The Cochrane Library, and conference and symposia proceedings in the English language from 1990 to July, 2000. A list of all relevant articles was sent to two experts in the field to identify any omissions or additional unpublished studies. SELECTION CRITERIA: Randomized trials in which elements of developmental care are compared to routine nursery care for infants < 37 weeks gestation and that measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted and all potentially relevant titles and abstracts were extracted. Retrieved articles were assessed for relevance independently by two reviewers, based on predetermined criteria. Articles that met all criteria for relevance were assessed for methodological quality based on predetermined criteria. Articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. Meta-analyses were conducted for each intervention where the same outcome measures and/or instruments were used within comparable time points. MAIN RESULTS: This review detected 31 eligible randomized controlled trials involving four major groups of developmental care interventions, 19 sub-groups and multiple clinical outcomes. The results of the review indicate that developmental care interventions demonstrate some benefit to preterm infants with respect to: improved short-term growth outcomes, decreased respiratory support, decreased length and cost of hospital stay, and improved neurodevelopmental outcomes to 24 months corrected age. These findings were based on two or three small trials for each outcome, and did not involve meta-analyses of more than two trials for any one outcome. Although a number of other benefits were demonstrated, those results were from single studies with small sample sizes. The lack of blinding of the assessors was a significant methodological flaw in half of the studies. The cost of the interventions and personnel was not considered in any of the studies. REVIEWER'S CONCLUSIONS: Because of the inclusion of multiple interventions in most studies, the determination of the effect of any single intervention is difficult. Although there is evidence of some benefit of developmental care interventions overall, and no major harmful effects reported, there were a large number of outcomes for which no or conflicting effects were demonstrated. The single trials that did show a significant effect of an intervention on a major clinical outcome were based on small sample sizes, and the findings were often not supported in other small trials. Before a clear direction for practice can be supported, evidence demonstrating more consistent effects of developmental care interventions on important short- and long-term clinical outcomes is needed. The economic impact of the implementation and maintenance of developmental care practices should be considered by individual institutions.

Asunto(s)

RESUMEN

BACKGROUND: Non-nutritive sucking is used during gavage feeding and in the transition from gavage to breast/bottle feeding in preterm infants. The rationale for this intervention is that non-nutritive sucking facilitates the development of sucking behaviour and improves digestion of enteral feedings. Non-nutritive sucking has been considered to be a benign intervention, although it has the potential to have a negative effect on breastfeeding or on the incidence of later oral aversion. OBJECTIVES: To determine whether non-nutritive sucking (NNS) in preterm infants influences: a) weight gain, b) energy intake, c) heart rate, d) oxygen saturation, e) length of hospital stay, f) intestinal transit time, g) age at full oral feeds, or h) any other clinically relevant outcomes. SEARCH STRATEGY: MEDLINE and CINAHL databases back to 1976 and the Cochrane Controlled Trials register were searched. Reference lists/bibliographies of relevant articles and reviews were also searched. A comprehensive list of relevant articles was sent to two major authors in this area. They were asked if they knew of any other published or unpublished studies relevant to the area that had not been included in the original list. SELECTION CRITERIA: All trials utilizing experimental or quasi-experimental designs in which non-nutritive sucking in preterm infants was compared to no provision of non-nutritive sucking. Measured clinically relevant outcomes. Reports were in English or a language for which a translator was available. Computerized searches were conducted by both reviewers. All potentially relevant titles and abstracts identified by either reviewer were extracted. All retrieved articles were assessed for relevance independently by each reviewer, based on a pre-determined set of criteria. The reference lists/bibliographies of each article were reviewed independently for additional relevant titles and were also retrieved and assessed for relevance. Articles that met all relevance criteria were then assessed for methodologic quality based on a predetermined set of criteria. Those articles judged to have the appropriate quality by both reviewers were included in the analysis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by the two authors. No subgroup analyses were performed because of the small number of studies related to the relevant outcomes. MAIN RESULTS: This review consisted of 19 studies, 13 of which were randomized controlled trials. NNS was found to decrease significantly the length of hospital stay in preterm infants. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, and age at full oral feeds). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds and behavior. No negative outcomes were reported in any of the studies. REVIEWER'S CONCLUSIONS: This review found a significant decrease in length of stay in preterm infants receiving a NNS intervention. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables (weight gain, energy intake, heart rate, oxygen saturation, intestinal transit time, and age at full oral feeds). The review identified other positive clinical outcomes of NNS: transition from tube to bottle feeds and behavior. No negative outcomes were reported in any of the studies. There were also a number of limitations of the presently available evidence related to the design of the studies, outcome variability, and lack of long-term data. Based on the available evidence, NNS in preterm infants would appear to have some clinical benefit. It does not appear to have any short-term negative effects. In view of the fact that there are no long-term data, further investigations are recommended. In order to facilitate meta-analysis of these data, future research in this area should involve outcome measures

Asunto(s)

RESUMEN

PURPOSE: To determine whether nonnutritive sucking (NNS) in preterm infants influences selected outcome variables. DESIGN: A systematic review, based on the Cochrane Collaboration format, of trials utilizing experimental or quasi-experimental designs in which NNS (by pacifier) was compared to no provision of NNS; related to naso/orogastric tube feedings, bottle feedings, or not associated with feeding. SAMPLE: All infants born at < 37 weeks gestation. This review consisted of 19 studies; 13 were randomized controlled trials. Sample sizes ranged from 10 to 59 infants and totaled 518 infants. MAIN OUTCOME VARIABLE: Weight gain, energy intake, heart rate, oxygen saturation, length of hospital stay, intestinal transit time, and postconceptional age at full oral feedings. RESULTS: NNS significantly decreased the length of hospital stay in preterm infants. The review did not reveal a consistent benefit of NNS with respect to other major clinical variables. No negative outcomes were reported in any of the studies.

Asunto(s)

Asunto(s)

RESUMEN

OBJECTIVE: To determine the effect of indwelling versus intermittent feeding tube placement on weight gain, apnea, and bradycardia in premature neonates. DESIGN: Eligible subjects were assigned randomly to either feeding tube method. Each subject was followed for 6 days. SETTING: The study was conducted in a secondary level neonatal intensive-care unit (NICU), a tertiary level NICU in a perinatal center, and a tertiary level NICU in a referral center. PATIENTS/PARTICIPANTS: Neonates who were 24-34 weeks gestational age, developmentally appropriate for gestational age, medically stable, on full enteral feedings through an orogastric or a nasogastric tube, and not fluid restricted. Ninety-three neonates were enrolled--49 indwelling group and 44 in the intermittent group. Nine neonates did not complete the study. INTERVENTIONS: Nasogastric indwelling feeding tubes were placed and left in site for up to 3 days. Orogastric intermittent feeding tubes were placed for each feeding and removed at completion of the feeding. MAIN OUTCOME MEASURES: Weight gain, apnea, and bradycardia. RESULTS: Members of both groups had similar demographic characteristics, clinical problems, and nutritional intake. No statistical differences were found between the two groups in weight gain or episodes of apnea and bradycardia. CONCLUSIONS: There were no statistically or clinically significant differences between the two groups. The intermittent method of feeding is more expensive. Because no clinical differences were found, the type of tube placement chosen for feeding the premature infant may be based on economics.

Asunto(s)

RESUMEN

Hydrostatic pressure and HeLa S3 cells were used (as a model system) to investigate the relationship of the cytoskeleton and histone gene expression. Exposure of HeLa S3 cells to hydrostatic pressure of 1000 - 10,000 psi (6.89 x 10(3) - 6.89 x 10(4) kPa) disrupts the cytoskeleton and reduces H1 and core histone mRNA and actin mRNA levels as determined by hybridization to specific DNA probes. Soluble and insoluble cell fractions were isolated from HeLa cells after lysis in Triton X-100 buffered with PIPES and being subjected to low-speed centrifugation. The insoluble fraction was designated the cytoskeletal fraction. At atmospheric pressure, 76% of H4 histone mRNA is associated with the cytoskeletal fraction and 24% of the H4 histone mRNA is in the soluble fraction. At 6000 and 10,000 psi for a duration of 10 min, H4 mRNA levels in the cytoskeletal fraction were reduced to 52 and 41%, respectively. The reduction of mRNA in the cytoskeletal fraction is accompanied by a corresponding increase of mRNA in the soluble cell fraction. The other core (H2A, H2B, and H3) and H1 histone mRNA transcripts exhibited similar sensitivity to pressure treatment. The effects of pressure on histone gene regulation may be mediated through alteration of mRNA-cytoskeleton association.

Asunto(s)

Asunto(s)

RESUMEN

Exposure of HeLa S3 cells to high hydrostatic pressure (6.89 x 10(3) to 6.89 x 10(4) kPa: 1000 to 10,000 lbfin-2) reduced core and H1 histone mRNA levels as determined by hybridization to specific histone DNA probes. At 4.14 x 10(4) kPa for 10 min core histone and H1 histone mRNA levels were reduced 32-38% and 56%, respectively. At 30 min postdecompression core mRNA levels returned to atmospheric control levels while H1 histone mRNA levels continued to be suppressed. Levels of macromolecular synthesis were monitored under hydrostatic pressure with radioactive precursors of RNA, DNA and protein. Macromolecular synthesis was shown to be suppressed in a dose-dependent manner with increasing magnitude and duration of pressure. To determine the influence of pressure on histone mRNA stability, actinomycin D (10 micrograms ml-1) was used to block RNA synthesis. Relative amounts of H4 and H1 mRNA were determined at atmospheric pressure and following treatment with actinomycin D (10 micrograms ml-1), pressure (4.14 x 10(4) kPa) and a combination of pressure and actinomycin D. This study shows that a synthesis component and a stability component are involved in the pressure-induced reduction of core histone mRNA. At 4.14 x 10(4) kPa for 15 min, there was a 42% reduction in core histone mRNA of which approximately one third was due a suppression of transcription and two thirds to a loss of mRNA stability. The pressure-induced reduction in histone mRNA is attributed to the instability of endogenous histone mRNA and a reduction in transcription/processing of new histone mRNA.

Asunto(s)

RESUMEN

A reduction in tubulin mRNA levels up to 35-40 min following pressure (10,000 psi for 5 min) was shown by cDNA hybridization in log growth phase and deciliated Tetrahymena. The level of tubulin mRNA increased to a maximum 1 hour after pressure release. Poly(A+) mRNA derived from pressure-treated and atmospheric control cells following deciliation was translated in vitro. The profile for tubulin synthesized in vitro closely resembled the tubulin mRNA profiles. In vivo tubulin synthesis measured by 35S methionine incorporation was suppressed 60%, 40 min following pressure release. The data supports the hypothesis that both transcription and post transcriptional events are sensitive to hydrostatic pressure.

Asunto(s)