We sought to determine the incidence of necrotizing enterocolitis (NEC) and spontaneous intestinal perforation (SIP) in surviving extremely low-birth-weight (ELBW, <1000 g birth weight) infants and ...to establish the impact of NEC on outcomes by hospital discharge and at 18 to 22 months adjusted age in a large, contemporary, population-based practice.
Hospital outcome data for all ELBW infants born in the greater Cincinnati region from 1998 to 2009 were extracted from the National Institute of Child Health Neonatal Research Network Database. Neurodevelopmental outcome at 18 to 22 months was assessed using Bayley Scales of Infant Development-II scores for Mental Developmental Index and Psychomotor Developmental Index. Multivariable logistic regression was used and adjusted odds ratios reported to control for confounders.
From 1998 to 2009, ELBW infants accounted for 0.5% of the 352 176 live-born infants in greater Cincinnati. The incidence of NEC was 12%, with a 50% case-fatality rate. Death before discharge, morbid complications of prematurity and neurodevelopmental impairment were all increased among infants diagnosed with NEC. Infants with surgical NEC and SIP had a higher incidence of death, but long-term neurodevelopmental outcomes were not different comparing surviving ELBW infants with medical NEC, surgical NEC and SIP.
Although ELBW infants comprise a very small proportion of live-born infants, those who develop NEC and SIP are at an increased risk for death, morbid complications of prematurity and neurodevelopmental impairment. No significant differences in neurodevelopmental outcomes were observed between the medical and surgical NEC and SIP groups.
Delayed cord clamping (DCC) may be beneficial in very-preterm and very-low-birth-weight infants.
This study was a randomized unmasked controlled trial. It was performed at three centers of the NICHD ...(National Institute of Child Health and Human Development) Neonatal Research Network. DCC in very-preterm and very-low-birth-weight infants will result in an increase in hematocrit levels at 4 h of age. Infants with a gestational age of 24 to 28 weeks were randomized to either early cord clamping (<10 s) or DCC (30 to 45 s). The primary outcome was venous hematocrit at 4 h of age. Secondary outcomes included delivery room management, selected neonatal morbidities and the need for blood transfusion during the infants' hospital stay.
A total of 33 infants were randomized: 17 to the immediate cord clamping group (cord clamped at 7.9±5.2 s, mean±s.d.) and 16 to the DCC (cord clamped at 35.2±10.1 s) group. Hematocrit was higher in the DCC group (45±8% vs 40±5%, P<0.05). The frequency of events during delivery room resuscitation was almost identical between the two groups. There was no difference in the hourly mean arterial blood pressure during the first 12 h of life; there was a trend in the difference in the incidence of selected neonatal morbidities, hematocrit at 2, 4 and 6 weeks, as well as the need for transfusion, but none of the differences was statistically significant.
A higher hematocrit is achieved by DCC in very-low-birth-weight infants, suggesting effective placental transfusion.
Chronic lung disease develops in approximately 30 percent of infants with a birth weight of less than 1 kg who survive the initial hospitalization.
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Lung inflammation resulting from mechanical ...injury, a high oxygen concentration, or infection contributes to the development of this condition.
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Low base-line serum cortisol concentrations and poor responses to physiologic doses of corticotropin have been associated with an increased risk of chronic lung disease among infants with very low weight at birth,
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suggesting that the inflammatory response to lung injury may be exaggerated.
Data from some, though not all, clinical trials suggest that the early . . .
Localized, transient polar cap flows impinging on the poleward boundary of the nightside auroral oval have been suggested to precede poleward boundary intensifications (PBIs), which are often ...followed by auroral streamers, some of which propagate equatorward and appear to lead to substorm auroral onset. While echo coverage often limits radar flow measurements, imaging of polar cap patches and arcs has the potential to monitor localized polar cap flows by tracing emission structures, previously associated with enhanced flows, over long distances. We use such imaging to examine if polar cap patches and arcs moving over large distances can be seen as possible precursors to presubstorm‐onset PBIs. We find evidence that such features, which are longitudinally narrow, propagate from the dayside polar region toward the nightside polar cap boundary prior to pre‐onset PBIs. This sequence indicates that transient activity in the dayside polar region may initiate polar cap patches and arcs that propagate across the polar cap and are followed by pre‐onset PBIs. Furthermore, we find evidence that expansion‐phase active aurora expanded poleward soon after additional polar cap patches and arcs reached close to the nightside polar cap boundary. The expansion phase auroral activity significantly weakened when polar cap patches/arcs disappeared. Our findings suggest that plasma transport originating from the dayside and reaching the nightside open‐closed boundary may trigger in plasma sheet flow bursts and play a crucial role in pre‐ and post‐onset auroral activity. Polar cap imaging offers the possibility for monitoring such localized, transient plasma transport over large distances.
Key Points
Polar cap patches and arcs are found to precede pre‐onset PBIs.Expansion‐phase further intensifications are also preceded by patches and arcs.Dayside region is found important for triggering flow bursts and substorms.
CRISPR-Cas9-based genetic screens are a powerful new tool in biology. By simply altering the sequence of the single-guide RNA (sgRNA), one can reprogram Cas9 to target different sites in the genome ...with relative ease, but the on-target activity and off-target effects of individual sgRNAs can vary widely. Here, we use recently devised sgRNA design rules to create human and mouse genome-wide libraries, perform positive and negative selection screens and observe that the use of these rules produced improved results. Additionally, we profile the off-target activity of thousands of sgRNAs and develop a metric to predict off-target sites. We incorporate these findings from large-scale, empirical data to improve our computational design rules and create optimized sgRNA libraries that maximize on-target activity and minimize off-target effects to enable more effective and efficient genetic screens and genome engineering.
Objectives.
To determine the mortality and morbidity for infants weighing 401 to 1500 g (very low birth weight VLBW) at birth by gestational age, birth weight, and gender.
Study Design.
Perinatal ...data were collected prospectively on an inborn cohort from January 1995 through December 1996 by 14 participating centers of the National Institute of Child Health and Human Development Neonatal Research Network and were compared with the corresponding data from previous reports. Sociodemographic factors, perinatal events, and the neonatal course to 120 days of life, discharge, or death were evaluated.
Results.
Eighty four percent of 4438 infants weighing 501 to 1500 g at birth survived until discharge to home or to a long-term care facility (compared with 80% in 1991 and 74% in 1988). Survival to discharge was 54% for infants 501 to 750 g at birth, 86% for those 751 to 1000 g, 94% for those 1001 to 1250 g, and 97% for those 1251 to 1500g. The incidence of chronic lung disease (CLD; defined as receiving supplemental oxygen at 36 weeks' postmenstrual age; 23%), proven necrotizing enterocolitis (NEC; 7%), and severe intracranial hemorrhage (ICH; grade III or IV; 11%) remained unchanged between 1991 and 1996. Furthermore, 97% of all VLBW infants and 99% of infants weighing <1000 g at birth had weights less than the 10th percentile at 36 weeks' postmenstrual age.
Mortality for 195 infants weighing 401 to 500 g was 89%, with nearly all survivors developing CLD. Mortality in infants weighing 501 to 600 g was 71%; among survivors, 62% had CLD, 35% had severe ICH, and 15% had proven NEC.
Conclusions.
Survival for infants between 501 and 1500 g at birth continued to improve, particularly for infants weighing <1000 g at birth. This improvement in survival was not associated with an increase in major morbidities, because the incidence of CLD, proven NEC, and severe ICH did not change. However, poor postnatal growth remains a major concern, occurring in 99% of infants weighing <1000 g at birth. Mortality and major morbidity (CLD, severe ICH, and NEC) remain high for the smallest infants, particularly those weighing <600 g at birth.
To determine statistically the extent to which current sheet scattering is sufficient to account for the observed ion isotropic boundaries (IBs) for <30 keV ions, we have computed IBs from our 3‐D ...empirical force‐balanced magnetic field, identified IBs in FAST observations, and investigated the model‐observation consistency. We have found in both model and FAST results the same dependences of IB latitudes on magnetic local time, ion energy, Kp, and solar wind dynamic pressure (PSW) levels: IB moves to higher latitudes from midnight toward dawn/dusk and to lower latitudes as energy increases and as Kp or PSW increases. The model predicts well the observed energy dependence, and the modeled IB latitudes match fairly well with those from FAST for Kp = 0. As Kp increases, the latitude agreement at midnight remains good but a larger discrepancy is found near dusk. The modeled IBs at the equator are located around the earthward boundary of highly isotropic ions observed by Time History of Events and Macroscale Interactions during Substorms at midnight and postmidnight, but with some discrepancy near dusk under high Kp. Thus, our results indicate that current sheet scattering generally plays the dominant role. The discrepancies suggest the importance of pitch angle scattering by electromagnetic ion cyclotron waves, which occur more often from dusk to noon and are more active during higher Kp. The comparison with the observed IBs is better with our model than under the nonforce‐balanced T89, indicating that using a forced‐balanced model improves the description of the magnetic field configuration and reinforces our conclusions regarding the role of current sheet scattering.
Key Points
Model IB latitude lower for higher‐energy ions and under higher Kp or PdGood agreement between the model IB and THEMIS and FAST observationsCurrent sheet scattering is the main cause of energy‐dependent IB
Azimuthally propagating low‐frequency waves (or wavy structures) often occur in a localized region of the near‐Earth plasma sheet and auroral arc immediately prior to auroral breakup. Although both ...are believed to be magnetospheric and ionospheric manifestations of a plasma sheet instability that may lead to substorm onset, the fundamental coupling processes behind their relationship are not yet understood. To address this question, we reexamined in detail a fortuitous conjunction event of prebreakup near‐Earth plasma sheet and auroral arc waves, initially reported by Uritsky et al. (2009) using the Time History of Events and Macroscale Interactions during Substorms space‐ground observations. The event exhibited a morphological one‐to‐one association between longitudinally propagating arc wave (LPAW) in the ionosphere and Pi2/Pc4 range wave activity in the plasma sheet. Our analysis revealed that (1) the LPAW was the periodic luminosity modulation of the growth phase arc by faint, diffuse, green line‐dominated auroral patches propagating westward along/near the arc, rather than some type of small‐scale arc structuring, such as auroral beads/rays/undulations; and (2) the plasma sheet wave, which had a diamagnetic nature, propagated duskward with accompanying coincident modulation of field‐aligned fluxes of 0.1–30 keV electrons. These findings suggest that the LPAW was likely connected to the plasma sheet wave via modulated diffuse precipitation of hard plasma sheet electrons (> ~1 keV), not via filamentary field‐aligned currents, as expected from the ballooning instability regime. Another potential implication is that such prebreakup low‐frequency wave activity in the near‐Earth plasma sheet is not necessarily guaranteed to initiate prebreakup auroral arc structuring.
Key Points
Longitudinally propagating auroral patches cause the prebreakup arc wave
The prebreakup plasma sheet wave modulates the energetic electron fluxes
The prebreakup waves are connected via a pitch angle diffusion process
To examine the predictive validity of the amplitude integrated electroencephalogram (aEEG) and stage of encephalopathy among infants with hypoxic-ischemic encephalopathy (HIE) eligible for ...therapeutic whole-body hypothermia.
Neonates were eligible for this prospective study if moderate or severe HIE occurred at <6 hours and an aEEG was obtained at <9 hours of age. The primary outcome was death or moderate/severe disability at 18 months.
There were 108 infants (71 with moderate HIE and 37 with severe HIE) enrolled in the study. aEEG findings were categorized as normal, with continuous normal voltage (n=12) or discontinuous normal voltage (n=12), or abnormal, with burst suppression (n=22), continuous low voltage (n=26), or flat tracing (n=36). At 18 months, 53 infants (49%) experienced death or disability. Severe HIE and an abnormal aEEG were related to the primary outcome with univariate analysis, whereas severe HIE alone was predictive of outcome with multivariate analysis. Addition of aEEG pattern to HIE stage did not add to the predictive value of the model; the area under the curve changed from 0.72 to 0.75 (P=.19).
The aEEG background pattern did not significantly enhance the value of the stage of encephalopathy at study entry in predicting death and disability among infants with HIE.
One of the signatures of magnetospheric substorms is the precipitation of high energy particles into the high latitude ionosphere. In this paper, we introduce a new method of tracking substorm ...particle precipitation using GPS Total Electron Content (TEC) and provide some preliminary observations of precipitation signatures from application of this method. Using TEC measurements from several GPS receivers, we examined particle precipitation signatures associated with two separate substorm events (4 October 2008 and 29 October 2008) and monitored the expansion of the high energy precipitation regions with a higher temporal and spatial resolution than previously available. For each event we have observed TEC signatures associated with substorm particle precipitation along 20 to 25 separate GPS raypaths from up to 7 GPS receivers located in the Canadian Arctic. This is in addition to particle injection signatures found in CLUSTER satellite data and precipitation signatures in ground based riometer data. Signature timing on different raypaths from different stations indicates a mainly northward (tailward) expansion of the precipitation (injection) region with a smaller westward (azimuthal) component for the events studied. By applying a triangulation method, we also calculated propagation velocity of the precipitation boundary in regions covered by our GPS receivers. For each substorm, expansion velocity ranged from 0.3–2 km/s northward and 0–1 km/s westward, and tended to decrease in magnitude at higher latitudes.
Key Points
Introduce a new technique of observing substorm particle injection using GPS TEC
Provide preliminary observations using this technique
Outline preliminary results from application of this technique
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