Optimal phylogenetic reconstruction of insertion and deletion events.

MOTIVATION: Insertions and deletions (indels) influence the genetic code in fundamentally distinct ways from substitutions, significantly impacting gene product structure and function. Despite their influence, the evolutionary history of indels is often neglected in phylogenetic tree inference and ancestral sequence reconstruction, hindering efforts to comprehend biological diversity determinants and engineer variants for medical and industrial applications. RESULTS: We frame determining the optimal history of indel events as a single Mixed-Integer Programming (MIP) problem, across all branch points in a phylogenetic tree adhering to topological constraints, and all sites implied by a given set of aligned, extant sequences. By disentangling the impact on ancestral sequences at each branch point, this approach identifies the minimal indel events that jointly explain the diversity in sequences mapped to the tips of that tree. MIP can recover alternate optimal indel histories, if available. We evaluated MIP for indel inference on a dataset comprising 15 real phylogenetic trees associated with protein families ranging from 165 to 2000 extant sequences, and on 60 synthetic trees at comparable scales of data and reflecting realistic rates of mutation. Across relevant metrics, MIP outperformed alternative parsimony-based approaches and reported the fewest indel events, on par or below their occurrence in synthetic datasets. MIP offers a rational justification for indel patterns in extant sequences; importantly, it uniquely identifies global optima on complex protein data sets without making unrealistic assumptions of independence or evolutionary underpinnings, promising a deeper understanding of molecular evolution and aiding novel protein design. AVAILABILITY AND IMPLEMENTATION: The implementation is available via GitHub at https://github.com/santule/indelmip.

Atom Interferometric Imaging of Differential Potentials Using an Atom Laser.

Interferometry is a prime technique for modern precision measurements. Atoms, unlike light, have significant interactions with electric, magnetic, and gravitational fields, making their use in interferometric applications particularly versatile. Here, we demonstrate atom interferometry to image optical and magnetic potential landscapes over an area exceeding 240 µm×600 µm. The differential potentials employed in our experiments generate phase imprints in an atom laser that are made visible through a Ramsey pulse sequence. We further demonstrate how advanced pulse sequences can enhance desired imaging features, e.g., to image steep potential gradients. A theoretical discussion is presented that provides a semiclassical analysis and matching numerics.

Current state and practice variation in the use of Meningitis/Encephalitis (ME) FilmArray panel in children.

BACKGROUND: The Meningitis/Encephalitis FilmArray® Panel (ME panel) was approved by the U.S. Food and Drug Administration in 2015 and provides rapid results when assessing patients with suspected meningitis or encephalitis. These patients are evaluated by various subspecialties including pediatric hospital medicine (PHM), pediatric emergency medicine (PEM), pediatric infectious diseases, and pediatric intensive care unit (PICU) physicians. The objective of this study was to evaluate the current use of the ME panel and describe the provider and subspecialty practice variation. METHODS: We conducted an online cross-sectional survey via the American Academy of Pediatrics Section of Hospital Medicine (AAP-SOHM) ListServe, Brown University PEM ListServe, and PICU Virtual pediatric system (VPS) Listserve. RESULTS: A total of 335 participants out of an estimated 6998 ListServe subscribers responded to the survey. 68% reported currently using the ME panel at their institutions. Among test users, most reported not having institutional guidelines on test indications (75%) or interpretation (76%). 58% of providers self-reported lack of knowledge of the test's performance characteristics. Providers from institutions that have established guidelines reported higher knowledge compared to those that did not (51% vs. 38%; p = 0.01). More PHM providers reported awareness of ME panel performance characteristics compared to PEM physicians (48% vs. 27%; p = 0.004); confidence in test interpretation was similar between both groups (72 vs. 69%; p = 0.80). CONCLUSION: Despite the widespread use of the ME panel, few providers report having institutional guidelines on test indications or interpretation. There is an opportunity to provide knowledge and guidance about the ME panel among various pediatric subspecialties.

Critical analysis of acute kidney injury in pediatric COVID-19 patients in the intensive care unit.

BACKGROUND AND OBJECTIVES: COVID-19 is responsible for the 2019 novel coronavirus disease pandemic. Despite the vast research about the adult population, there has been little data collected on acute kidney injury (AKI) epidemiology, associated risk factors, treatments, and mortality in pediatric COVID-19 patients admitted to the ICU. AKI is a severe complication of COVID-19 among children and adolescents. METHODS: A comprehensive literature search was conducted in PubMed/MEDLINE and Cochrane Center Trials to find all published literature related to AKI in COVID-19 patients, including incidence and outcomes. RESULTS: Twenty-four studies reporting the outcomes of interest were included. Across all studies, the overall sample size of COVID positive children was 1,247 and the median age of this population was 9.1 years old. Among COVID positive pediatric patients, there was an AKI incidence of 30.51%, with only 0.56% of these patients receiving KRT. The mortality was 2.55% among all COVID positive pediatric patients. The incidence of multisystem inflammatory syndrome in children (MIS-C) among COVID positive patients was 74.29%. CONCLUSION: AKI has shown to be a negative prognostic factor in adult patients with COVID-19 and now also in the pediatric cohort with high incidence and mortality rates. Additionally, our findings show a strong comparison in epidemiology between adult and pediatric COVID-19 patients; however, they need to be confirmed with additional data and studies.

Provider Consensus on Candidate Protective and Risk Factors for Adverse Psychosocial Outcomes Following Discharge From a PICU: A Modified Delphi Study.

OBJECTIVES: Pediatric palliative care promotes interdisciplinary, family-centered care when children are faced with diagnoses threatening length and/or quality of life. A significant knowledge gap remains in how to best match pediatric palliative care resources to palliate the psychosocial impact of a PICU admission. This study was designed to identify drivers of adverse post-PICU psychosocial outcomes related to social determinants of health to inform pediatric palliative care services and improve post-PICU psychosocial outcomes. DESIGN: Modified Delphi technique to develop consensus regarding social determinants of health and clinical factors affecting post-ICU psychosocial outcomes. SETTING: All Delphi rounds were via an electronically mailed survey link. SUBJECTS: First-round participants were PICU and pediatric palliative care clinicians at the study institution. Subsequent rounds invited participants from national PICU and pediatric palliative care professional online listserves. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Consensus was defined a priori as items assigned a score greater than or equal to 4 (5-point scale) by greater than75% of respondents. One-hundred twenty-six surveys were returned and scored. Social determinants of health risk factors included child protective services involvement (91%), caregiver with intellectual disability (87%), lack of friend or family support (82%), caregiver with behavioral health diagnosis (81%), teenage caregiver (79%), transportation challenges (79%), and language/cultural barrier (76%). Clinical risk factors included new home ventilator (94%), new tracheostomy (90%), greater than or equal to 3 hospitalizations in the prior 6 months (88%), and greater than or equal to 3 hospitalizations in the prior 12 months (82%). Social determinants of health protective factors included extended family support (91%), caregivers in a committed relationship (79%), and caregiver optimism (78%). Respondents reported that pediatric palliative care services had the greatest impact on caregiver satisfaction with the healthcare system (90%) and increased family involvement with state social services programs (80%). CONCLUSIONS: Consensus on candidate risk and protective factors for post-ICU psychosocial challenges and candidate pediatric palliative care-sensitive variables were identified. Further research is needed to operationalize and optimize a screening tool based on these consensus items and test it prospectively.

SENTINEL1: Two-Season Study of Respiratory Syncytial Virus Hospitalizations among U.S. Infants Born at 29 to 35 Weeks' Gestational Age Not Receiving Immunoprophylaxis.

OBJECTIVE: The SENTINEL1 observational study characterized confirmed respiratory syncytial virus hospitalizations (RSVH) among U.S. preterm infants born at 29 to 35 weeks' gestational age (wGA) not receiving respiratory syncytial virus (RSV) immunoprophylaxis (IP) during the 2014 to 2015 and 2015 to 2016 RSV seasons. STUDY DESIGN: All laboratory-confirmed RSVH at participating sites during the 2014 to 2015 and 2015 to 2016 RSV seasons (October 1-April 30) lasting ≥24 hours among preterm infants 29 to 35 wGA and aged <12 months who did not receive RSV IP within 35 days before onset of symptoms were identified and characterized. RESULTS: Results were similar across the two seasons. Among infants with community-acquired RSVH (N = 1,378), 45% were admitted to the intensive care unit (ICU) and 19% required invasive mechanical ventilation (IMV). There were two deaths. Infants aged <6 months accounted for 78% of RSVH observed, 84% of ICU admissions, and 91% requiring IMV. Among infants who were discharged from their birth hospitalization during the RSV season, 82% of RSVH occurred within 60 days of birth hospitalization discharge. CONCLUSION: Among U.S. preterm infants 29 to 35 wGA not receiving RSV IP, RSVH are often severe with almost one-half requiring ICU admission and about one in five needing IMV.

Growth and Changing Characteristics of Pediatric Intensive Care 2001-2016.

OBJECTIVES: We assessed the growth, distribution, and characteristics of pediatric intensive care in 2016. DESIGN: Hospitals with PICUs were identified from prior surveys, databases, online searching, and clinician networking. A structured web-based survey was distributed in 2016 and compared with responses in a 2001 survey. SETTING: PICUs were defined as a separate unit, specifically for the treatment of children with life-threatening conditions. PICU hospitals contained greater than or equal to 1 PICU. SUBJECTS: Physician medical directors and nurse managers. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: PICU beds per pediatric population (< 18 yr), PICU bed distribution by state and region, and PICU characteristics and their relationship with PICU beds were measured. Between 2001 and 2016, the U.S. pediatric population grew 1.9% to greater than 73.6 million children, and PICU hospitals decreased 0.9% from 347 to 344 (58 closed, 55 opened). In contrast, PICU bed numbers increased 43% (4,135 to 5,908 beds); the median PICU beds per PICU hospital rose from 9 to 12 (interquartile range 8, 20 beds). PICU hospitals with greater than or equal to 15 beds in 2001 had significant bed growth by 2016, whereas PICU hospitals with less than 15 beds experienced little average growth. In 2016, there were eight PICU beds per 100,000 U.S. children (5.7 in 2001), with U.S. census region differences in bed availability (6.8 to 8.8 beds/100,000 children). Sixty-three PICU hospitals (18%) accounted for 47% of PICU beds. Specialized PICUs were available in 59 hospitals (17.2%), 48 were cardiac (129% growth). Academic affiliation, extracorporeal membrane oxygenation availability, and 24-hour in-hospital intensivist staffing increased with PICU beds per hospital. CONCLUSIONS: U.S. PICU bed growth exceeded pediatric population growth over 15 years with a relatively small percentage of PICU hospitals containing almost half of all PICU beds. PICU bed availability is variable across U.S. states and regions, potentially influencing access to care and emergency preparedness.

Validating a prediction modeling tool for left ventricular outflow tract (LVOT) obstruction after transcatheter mitral valve replacement (TMVR).

OBJECTIVE: Demonstrate proof-of-concept validation of a computed tomography (CT) computer-aided design prediction modeling tool to identify patients at risk for left ventricular outflow tract (LVOT) obstruction in transcatheter mitral valve replacement (TMVR). BACKGROUND: LVOT obstruction is a significant and even fatal consequence of TMVR. METHODS: From August 2013 to August 2017, 38 patients in 5 centers underwent TMVR with compassionate use of balloon-expandable valves for severe mitral valve dysfunction because of degenerative surgical mitral ring, bioprosthesis, or severe native mitral stenosis from to severe mitral annular calcification. All patients had preprocedural CT scans performed for anatomic screening, intraprocedural TEE and invasive hemodynamics performed. Preprocedural prediction modeling was performed utilizing computer-aided design (CAD) of the neo-LVOT post-TMVR. Post-TMVR CT scans were obtained and compared to pre-TMVR LVOT modeling datasets for validation. RESULTS: All patients underwent successful TMVR without device embolization. Seven of the 38 patients experienced LVOT obstruction, defined as an increase of ≥10 mmHg LVOT peak gradient post-TMVR. Anatomic screening using CT was validated in 20/38 patients as preprocedural predicted neo-LVOT surface area correlated well with post-TMVR measurements (R2 = 0.8169, P < 0.0001). A receiver operating curve curve found a predicted neo-LVOT surface area of ≤ 189.4 mm2 to have 100% sensitivity and 96.8% specificity for predicting TMVR-induced LVOT obstruction. CONCLUSION: CAD design and CT postprocessing are indispensable tools in predicting LVOT obstruction and necessary for anatomic screening in percutaneous TMVR.

Prospective, randomized comparison of 3-dimensional computed tomography guidance versus TEE data for left atrial appendage occlusion (PRO3DLAAO).

BACKGROUND: Preliminary data comparing 3-dimensional computed tomography (3D-CT) to transesophageal echocardiography (TEE) for left atrial appendage occlusion (LAAO) indicates that 3D-CT provides more accurate measurements and improves case planning. Therefore, we conducted a pilot study comparing 3D-CT to TEE in occluder selection accuracy and procedural efficiency. METHODS: From May 2016 to February 2017, 24 patients were prospectively randomized to undergo LAAO using either TEE or 3D-CT. The primary endpoint was device accuracy while the secondary endpoints included # devices per case, # guide catheters used per case, # fluoroscopy angles used, procedure time, fluoroscopy time, radiation dose, and major adverse events (stroke, MI, device embolization, perforation, death). RESULTS: Procedure success was 100% and 92% for the 3D-CT and 2D-TEE cohorts respectively. Accuracy for 1st device selection 92% and 27% (P = .01) for 3D-CT and 2D-TEE respectively but with intra-procedural upsizing in the 2D-TEE cohort, the 2D-TEE cohort accuracy increased to 64% while the 3D-CT groups 92% was accurate (P = .33). Case planning using 3D-CT was significantly more efficient with respect to device utilization (CT 1.33 ± 0.7 vs. 2D-TEE 2.5 ± 1.2 P = .01), guide catheters (CT 1 vs. 2D-TEE 1.7 ± 0.8 P = .01) and procedure time (3D-CT 55 ± 17 min vs. 2D-TEE 73 ± 24 min P < .05). One major adverse event, a stroke occurred in the 2D-TEE group. CONCLUSION: In this single-center pilot study, CT guided LAAO case planning was associated with improved device selection accuracy and procedural efficiency. This study data supports the notion that comprehensive 3D assessment significantly simplifies LAAO, minimizing the time and number of steps needed.

Correlation of Bedside Pediatric Early Warning System Score to Interventions During Peritransport Period.

BACKGROUND: The Bedside Pediatric Early Warning System score is a validated measure of severity of illness in acute care inpatient settings. Its potential as a remote assessment tool for interfacility transport has not been evaluated. We hypothesized that the Bedside Pediatric Early Warning System score was associated with need for intervention during the peritransport period and patient disposition. METHODS: We retrospectively evaluated children transported by a regional pediatric team during a 6-month period. Bedside Pediatric Early Warning System scores were calculated at the triage phone call, the transport team arrival, and at transfer of care to the hospital team. The primary outcome was the receipt of significant intervention during the peritransport period, with additional outcomes of destination (ICU, ward, emergency department) in the regional hospital. Scores are presented as median values (interquartile range). RESULTS: There were 564 children who underwent transport; 139 (25%) received interventions; and 205 (36%) were transferred to the PICU, 231 (41%) to the ward, and 127 (23%) to the emergency department. Scores were 2 (1-5; median interquartile range) in children receiving no in-transport interventions, 8 (5-11) in children receiving any intervention (p < 0.001), and 10 (7-14) in children receiving more than one intervention. Children transferred to the PICU had higher scores 6 (3-10), than children transferred to a ward 3 (1-6) or the emergency department 2 (1-3) (p < 0.001). CONCLUSIONS: The Bedside Pediatric Early Warning System score at the time of initial referral is a useful measure of severity of illness reflected by the subsequent provision of significant peritransport intervention and the transfer destination.

Negative-Mass Hydrodynamics in a Spin-Orbit-Coupled Bose-Einstein Condensate.

A negative effective mass can be realized in quantum systems by engineering the dispersion relation. A powerful method is provided by spin-orbit coupling, which is currently at the center of intense research efforts. Here we measure an expanding spin-orbit coupled Bose-Einstein condensate whose dispersion features a region of negative effective mass. We observe a range of dynamical phenomena, including the breaking of parity and of Galilean covariance, dynamical instabilities, and self-trapping. The experimental findings are reproduced by a single-band Gross-Pitaevskii simulation, demonstrating that the emerging features-shock waves, soliton trains, self-trapping, etc.-originate from a modified dispersion. Our work also sheds new light on related phenomena in optical lattices, where the underlying periodic structure often complicates their interpretation.

SENTINEL1: An Observational Study of Respiratory Syncytial Virus Hospitalizations among U.S. Infants Born at 29 to 35 Weeks' Gestational Age Not Receiving Immunoprophylaxis.

Objective SENTINEL1 characterized U.S. preterm infants 29 to 35 weeks' gestational age (wGA) < 12 months old hospitalized for laboratory-confirmed respiratory syncytial virus (RSV) disease and not receiving RSV immunoprophylaxis during the 2014 to 2015 RSV season. Study Design This is a noninterventional, observational, cohort study. Results A total of 702 infants were hospitalized with community-acquired RSV disease, of whom an estimated 42% were admitted to the intensive care unit (ICU) and 20% required invasive mechanical ventilation (IMV). Earlier gestational age and younger chronologic age were associated with an increased frequency of RSV-confirmed hospitalization (RSVH), ICU admission, and IMV. Among infants 29 to 32 wGA and < 3 months of age, 68% required ICU admission and 44% required IMV. One death occurred of an infant 29 wGA. Among the 212 infants enrolled for in-depth analysis of health care resource utilization, mean and median RSVH charges were $55,551 and $27,461, respectively, which varied by intensity of care required. Outpatient visits were common, with 63% and 62% of infants requiring visits before and within 1 month following the RSVH, respectively. Conclusion Preterm infants 29 to 35 wGA are at high risk for severe RSV disease, which imposes a substantial health burden, particularly in the first months of life.

Augmentation of CFTR maturation by S-nitrosoglutathione reductase.

S-nitrosoglutathione (GSNO) reductase regulates novel endogenous S-nitrosothiol signaling pathways, and mice deficient in GSNO reductase are protected from airways hyperreactivity. S-nitrosothiols are present in the airway, and patients with cystic fibrosis (CF) tend to have low S-nitrosothiol levels that may be attributed to upregulation of GSNO reductase activity. The present study demonstrates that 1) GSNO reductase activity is increased in the cystic fibrosis bronchial epithelial (CFBE41o(-)) cells expressing mutant F508del-cystic fibrosis transmembrane regulator (CFTR) compared with the wild-type CFBE41o(-) cells, 2) GSNO reductase expression level is increased in the primary human bronchial epithelial cells expressing mutant F508del-CFTR compared with the wild-type cells, 3) GSNO reductase colocalizes with cochaperone Hsp70/Hsp90 organizing protein (Hop; Stip1) in human airway epithelial cells, 4) GSNO reductase knockdown with siRNA increases the expression and maturation of CFTR and decreases Stip1 expression in human airway epithelial cells, 5) increased levels of GSNO reductase cause a decrease in maturation of CFTR, and 6) a GSNO reductase inhibitor effectively reverses the effects of GSNO reductase on CFTR maturation. These studies provide a novel approach to define the subcellular location of the interactions between Stip1 and GSNO reductase and the role of S-nitrosothiols in these interactions.

Vortex Pinning and Dynamics in the Neutron Star Crust.

The nature of the interaction between superfluid vortices and the neutron star crust, conjectured by Anderson and Itoh in 1975 to be at the heart vortex creep and the cause of glitches, has been a long-standing question in astrophysics. Using a qualitatively new approach, we follow the dynamics as superfluid vortices move in response to the presence of "nuclei" (nuclear defects in the crust). The resulting motion is perpendicular to the force, similar to the motion of a spinning top when pushed. We show that nuclei repel vortices in the neutron star crust, and characterize the force per unit length of the vortex line as a function of the vortex element to the nucleus separation.

Hypoxia-induced changes in protein s-nitrosylation in female mouse brainstem.

Exposure to hypoxia elicits an increase in minute ventilation that diminishes during continued exposure (roll-off). Brainstem N-methyl-D-aspartate receptors (NMDARs) and neuronal nitric oxide synthase (nNOS) contribute to the initial hypoxia-induced increases in minute ventilation. Roll-off is regulated by platelet-derived growth factor receptor-ß (PDGFR-ß) and S-nitrosoglutathione (GSNO) reductase (GSNOR). S-nitrosylation inhibits activities of NMDAR and nNOS, but enhances GSNOR activity. The importance of S-nitrosylation in the hypoxic ventilatory response is unknown. This study confirms that ventilatory roll-off is virtually absent in female GSNOR(+/-) and GSNO(-/-) mice, and evaluated the location of GSNOR in female mouse brainstem, and temporal changes in GSNOR activity, protein expression, and S-nitrosylation status of GSNOR, NMDAR (1, 2A, 2B), nNOS, and PDGFR-ß during hypoxic challenge. GSNOR-positive neurons were present throughout the brainstem, including the nucleus tractus solitarius. Protein abundances for GSNOR, nNOS, all NMDAR subunits and PDGFR-ß were not altered by hypoxia. GSNOR activity and S-nitrosylation status temporally increased with hypoxia. In addition, nNOS S-nitrosylation increased with 3 and 15 minutes of hypoxia. Changes in NMDAR S-nitrosylation were detected in NMDAR 2B at 15 minutes of hypoxia. No hypoxia-induced changes in PDGFR-ß S-nitrosylation were detected. However, PDGFR-ß phosphorylation increased in the brainstems of wild-type mice during hypoxic exposure (consistent with roll-off), whereas it did not rise in GSNOR(+/-) mice (consistent with lack of roll-off). These data suggest that: (1) S-nitrosylation events regulate hypoxic ventilatory response; (2) increases in S-nitrosylation of NMDAR 2B, nNOS, and GSNOR may contribute to ventilatory roll-off; and (3) GSNOR regulates PDGFR-ß phosphorylation.

The swan-neck lesion: proximal tubular adaptation to oxidative stress in nephropathic cystinosis.

Cystinosis is an inherited disorder resulting from a mutation in the CTNS gene, causing progressive proximal tubular cell flattening, the so-called swan-neck lesion (SNL), and eventual renal failure. To determine the role of oxidative stress in cystinosis, histologic sections of kidneys from C57BL/6 Ctns(-/-) and wild-type mice were examined by immunohistochemistry and morphometry from 1 wk to 20 mo of age. Additional mice were treated from 1 to 6 mo with vehicle or mitoquinone (MitoQ), an antioxidant targeted to mitochondria. The leading edge of the SNL lost mitochondria and superoxide production, and became surrounded by a thickened tubular basement membrane. Progression of the SNL as determined by staining with lectin from Lotus tetragonolobus accelerated after 3 mo, but was delayed by treatment with MitoQ (38 ± 4% vs. 28 ± 1%, P < 0.01). Through 9 mo, glomeruli had retained renin staining and intact macula densa, whereas SNL expressed transgelin, an actin-binding protein, but neither kidney injury molecule-1 (KIM-1) nor cell death was observed. After 9 mo, clusters of proximal tubules exhibited localized oxidative stress (4-hydroxynonenal binding), expressed KIM-1, and underwent apoptosis, leading to the formation of atubular glomeruli and accumulation of interstitial collagen. We conclude that nephron integrity is initially maintained in the Ctns(-/-) mouse by adaptive flattening of cells of the SNL through loss of mitochondria, upregulation of transgelin, and thickened basement membrane. This adaptation ultimately fails in adulthood, with proximal tubular disruption, formation of atubular glomeruli, and renal failure. Antioxidant treatment targeted to mitochondria delays initiation of the SNL, and may provide therapeutic benefit in children with cystinosis.

Tubular obstruction leads to progressive proximal tubular injury and atubular glomeruli in polycystic kidney disease.

In polycystic kidney disease (PKD), renal parenchyma is destroyed by cysts, hypothesized to obstruct nephrons. A signature of unilateral ureteral obstruction, proximal tubular atrophy leads to formation of atubular glomeruli. To determine whether this process occurs in PKD, kidneys from pcy mice (moderately progressive PKD), kidneys from cpk mice (rapidly progressive PKD), and human autosomal dominant PKD were examined in early and late stages. Integrity of the glomerulotubular junction and proximal tubular mass were determined in sections stained with Lotus tetragonolobus lectin. Development of proximal tubular atrophy and atubular glomeruli was determined in serial sections of individual glomeruli. In pcy mice, most glomerulotubular junctions were normal at 20 weeks, but by 30 weeks, 56% were atrophic and 25% of glomeruli were atubular; glomerulotubular junction integrity decreased with increasing cyst area (r = 0.83, P < 0.05). In cpk mice, all glomerulotubular junctions were normal at 10 days, but by 19 days, 26% had become abnormal. In early-stage autosomal dominant PKD kidneys, 50% of glomeruli were atubular or attached to atrophic tubules; in advanced disease, 100% were abnormal. Thus, proximal tubular injury in cystic kidneys closely parallels that observed with ureteral obstruction. These findings support the hypothesis that, in renal cystic disorders, cyst-dependent obstruction of medullary and cortical tubules initiates a process culminating in widespread destruction of proximal convoluted tubules at the glomerulotubular junction.

The Fate of Nephrons in Congenital Obstructive Nephropathy: Adult Recovery is Limited by Nephron Number Despite Early Release of Obstruction.

PURPOSE: Urinary tract obstruction and reduced nephron number often occur together as a result of maldevelopment of the kidneys and the urinary tract. We determined the role of nephron number on adaptation of the remaining nephrons of mice subjected to neonatal partial unilateral ureteral obstruction followed through adulthood. MATERIALS AND METHODS: Wild-type and Os/+ mice (the latter with 50% fewer nephrons) underwent sham operation or partial unilateral ureteral obstruction in the first 2 days of life. Additional mice underwent release of unilateral ureteral obstruction at 7 days. All kidneys were harvested at 3 weeks (weaning) or 6 weeks (adulthood). Glomerular number and area, glomerulotubular junction integrity, proximal tubular volume fraction and interstitial fibrosis were measured by histomorphometry. RESULTS: In the obstructed kidney unilateral ureteral obstruction caused additional nephron loss in Os/+ but not in wild-type mice. Glomerular growth from 3 to 6 weeks was impaired by ipsilateral obstruction and not preserved by release in wild-type or Os/+ mice. Proximal tubular growth was impaired and interstitial collagen was increased by ipsilateral obstruction in all mice. These conditions were attenuated by release of unilateral ureteral obstruction in wild-type mice but were not restored in Os/+ mice. Unilateral ureteral obstruction increased interstitial collagen in the contralateral kidney while release of obstruction enhanced tubular growth and reduced interstitial collagen. CONCLUSIONS: Unilateral ureteral obstruction in early postnatal development impairs adaptation to reduced nephron number and induces additional nephron loss despite release of obstruction. Premature and low birth weight infants with congenital obstructive nephropathy are likely at increased risk for progression of chronic kidney disease.

A multicentered prospective analysis of diagnosis, risk factors, and outcomes associated with pediatric ventilator-associated pneumonia.

OBJECTIVE: To assess risk factors and outcomes associated with pediatric ventilator-associated pneumonia. DESIGN: Multicentered prospective observational cohort. SETTING: Children's hospitals in the United States. PATIENTS: Mechanically ventilated patients less than 18 years old. MEASUREMENTS AND MAIN RESULTS: Prospective evaluation of the prevalence, risk factors, and outcomes of pediatric ventilator-associated pneumonia along with evaluation of diagnostic criterion for pediatric ventilator-associated pneumonia. The prevalence of pediatric ventilator-associated pneumonia was 5.2% (n = 2,082), for a rate of 7.1/1,000 ventilator days. Patients with ventilator-associated pneumonia had a longer unadjusted ICU length of stay (p < 0.0001) and increased length of mechanical ventilation by more than 11 days (p < 0.0001). After adjustment for patient factors, ICU length of stay (p = 0.03) and mechanical ventilation days (p = 0.001) remained significant. Patients with ventilator-associated pneumonia were almost three times more likely to die (p = 0.007). Independent risk factors for ventilator-associated pneumonia were reintubation and part-time ventilation. CONCLUSIONS: Pediatric ventilator-associated pneumonia is common in mechanically ventilated pediatric patients. These patients have longer length of stay, longer duration of mechanical ventilation, and increased risk for mortality.

Risk Factors for Failed Tracheal Intubation in Pediatric and Neonatal Critical Care Specialty Transport.

Abstract Objective. Nearly 200,000 pediatric and neonatal transports occur in the United States each year with some patients requiring tracheal intubation. First-pass intubation rates in both pediatric and adult transport literature are variable as are the factors that influence intubation success. This study sought to determine risk factors for failed tracheal intubation in neonatal and pediatric transport. Methods. A retrospective chart review was performed over a 2.5-year period. Data were collected from a hospital-based neonatal/pediatric critical care transport team that transports 2,500 patients annually, serving 12,000 square miles. Patients were eligible if they were transported and tracheally intubated by the critical care transport team. Patients were categorized into two groups for data analysis: (1) no failed intubation attempts and (2) at least one failed intubation attempt. Data were tabulated using Epi Info Version 3.5.1 and analyzed using SPSSv17.0. Results. A total of 167 patients were eligible for enrollment and were cohorted by age (48% pediatric versus 52% neonatal). Neonates were more likely to require multiple attempts at intubation when compared to the pediatric population (69.6% versus 30.4%, p = 0.001). Use of benzodiazepines and neuromuscular blockade was associated with increased successful first attempt intubation rates (p = 0.001 and 0.008, respectively). Use of opiate premedication was not associated with first-attempt intubation success. The presence of comorbid condition(s) was associated with at least one failed intubation attempt (p = 0.006). Factors identified with increasing odds of at least one intubation failure included, neonatal patients (OR 3.01), tracheal tube size ≤ 2.5 mm (OR 3.78), use of an uncuffed tracheal tube (OR 6.85), and the presence of a comorbid conditions (OR 2.64). Conclusions. There were higher rates of tracheal intubation failure in transported neonates when compared to pediatric patients. This risk may be related to the lack of benzodiazepine and neuromuscular blocking agents used to facilitate intubation. The presence of a comorbid condition is associated with a higher risk of tracheal intubation failure.