Engagement of DNA and H3K27me3 by the CBX8 chromodomain drives chromatin association.

Polycomb repressive complex 1 (PRC1) is critical for mediating gene repression during development and adult stem cell maintenance. Five CBX proteins, CBX2,4,6,7,8, form mutually exclusive PRC1 complexes and are thought to play a role in the association of PRC1 with chromatin. Specifically, the N-terminal chromodomain (CD) in the CBX proteins is thought to mediate specific targeting to methylated histones. For CBX8, however, the chromodomain has demonstrated weak affinity and specificity for methylated histones in vitro, leaving doubt as to its role in CBX8 chromatin association. Here, we investigate the function of the CBX8 CD in vitro and in vivo. We find that the CD is in fact a major driver of CBX8 chromatin association and determine that this is driven by both histone and previously unrecognized DNA binding activity. We characterize the structural basis of histone and DNA binding and determine how they integrate on multiple levels. Notably, we find that the chromatin environment is critical in determining the ultimate function of the CD in CBX8 association.

Assessment of upper airway patency in spontaneously breathing non-intubated neonates and infants undergoing conventional MRI of head and neck.

PURPOSE: Neonates and infants frequently undergo MRI examinations of the brain or head and neck in spontaneous respiration. This study aims to evaluate the patency of the upper airway and associated risk factors in spontaneously breathing neonates and infants undergoing MRI of head and neck. METHODS: Airway patency was assessed on sagittal and axial MRI images of the head and neck region for neonates and infants retrospectively. Anteroposterior diameters were measured at the soft palate and tongue levels as well as a lateral diameter at the tongue level for the patent airway. Chart review for risk factors was carried out. RESULTS: A total of 831 children between 0 and 12 months of age had an MRI. Eighty-two children with spontaneous ventilation were included. The airway was occluded in 29/82 (35%) of children. Twenty-four out of 29 (83%) children with airway occlusion had a depressed level of consciousness, 7/24 (29%) of whom were sedated with a single dose of benzodiazepine and 17/24 (71%) were on anti-epileptic therapy for an underlying seizure disorder and/or hypoxic ischemic encephalopathy. Forty-three out of 82 (65%) of children had an open airway. The airway diameters (mean ± SD) were 5.9 ± 2 mm (anteroposterior (AP) at soft palate), 7.4 ± 2.9 mm (lateral at soft palate), and 6.3 mm ± 1.6 (AP at dorsum of tongue). CONCLUSION: A significant proportion of spontaneously breathing neonates and infants with hypoxic ischemic encephalopathy or sedation show evidence of airway obstruction during MRI. Careful pre-MRI screening for decision of spontaneous breathing versus artificial airway support during MRI and robust airway monitoring during MRI are required for these vulnerable children.

Does obesity prolong anesthesia in children undergoing common ENT surgery?

OBJECTIVES: To report the epidemiology of obesity in a pediatric surgical population and determine whether obesity is a risk factor for longer anesthesia duration. BACKGROUND: Childhood obesity is a significant public health problem in the United States. Epidemiologic studies on pediatric surgical populations have been limited to states with very high prevalence of adult obesity (Michigan, Texas). Data from other states and more recent data since 2006 are unavailable. METHODS: We examined anesthesia records for surgical patients age 2-18 years at Columbia University Medical Center from January 2009 to December 2010. Patients undergoing bariatric surgery or those with records missing preoperative height or weight data were excluded. Body mass index (BMI) was calculated as weight (kg)/height (m(2) ). BMI ≥95th percentile according to national growth charts were considered obese. RESULTS: We reviewed 9522 patients of which 1639 were obese (17.2%). The sex-age category interaction on obesity was not significant using logistic regression (P = 0.11). Among surgical groups, the otolaryngology (ENT) cohort had the highest obesity rate (21.7%, 360/1656). Obese children who had tonsillectomy, adenoidectomy, or both did not have a prolonged anesthetic (P = 0.33) or surgical duration (P = 0.61) compared with nonobese children, adjusting for surgeon, season, surgical procedure code, and ASA status. CONCLUSION: Children presenting for surgery, particularly the ENT cohort, have a high prevalence of obesity. Obese and nonobese children who had tonsillectomy, adenoidectomy, or both had comparable durations of anesthesia. Therefore, obesity did not lead to longer anesthetic duration.

A Randomized Controlled Trial Examining the Effect of Topical Refrigerant Spray on the Perception of an Instantaneous Noxious Stimulus.

Purpose: Topical refrigerant spray is commonly used with routine hand injections despite mixed evidence about its efficacy in reducing the pain experience. We hypothesize that the use of topical refrigerant spray decreases the pain experience of an instantaneous noxious stimulus. Methods: Eighty adult volunteer participants were enrolled in the study. We constructed an instrument using the smooth end of a Kirschner wire mounted to the spring of a ballpoint pen to apply an instantaneous noxious stimulus to the long (middle) finger proximal nail fold. Participants completed two trials and were randomized to receive the topical refrigerant spray before either the first or second stimulus and on either the left or right side. Participants were asked to rate the pain of each experience using an 11-point Likert scale and indicate which condition they preferred, if any. Results: The mean pain ratings for the spray and no-spray conditions were 2.0 and 4.3, respectively, giving a mean difference of -2.3 (P < .001, α = 0.05). Subgroup analysis showed no significant effect of sex or medical versus nonmedical occupation (P = .28 and .11 respectively) on the mean difference in pain rating between the two conditions. Participants who received the spray first had a higher mean difference in pain rating (2.7) than that in those who received it second (1.9). Fifty-nine participants preferred the spray, whereas 21 participants either preferred no spray or had no preference (P < .0001). Conclusions: The use of topical refrigerant spray significantly decreased the perception of pain from an instantaneous noxious stimulus. A significant majority of participants also preferred the topical refrigerant spray condition. The use of topical refrigerant spray for painful procedures, such as needle insertions, may improve the overall patient experience. Type of study/level of evidence: Therapeutic I.

Frequency of Follow-Up Assessment for Post-Intensive Care Syndrome Among Alert and Non-Delirious Critically Ill Patients.

INTRODUCTION: Many patients surviving critical illness develop post-intensive care syndrome, a constellation of psychological, physical, and cognitive symptoms which can have long-term consequences. Physicians and nurses at our large rural teaching hospital treat many of the critically ill patients in the state. Our focus has been the subset of these critically ill patients who were alert and not delirious for multiple consecutive days. The goal of our retrospective cohort study was to estimate the percentage of the patients with multiple intensive care unit days alert and not delirious who had follow-up assessments for post-intensive care syndrome within 15 months. METHODS: The inclusion criteria for the case series of randomly selected patients were: adults defined as patients aged >17 years on the date of hospital admission between October 2014 and December 2020, present in a critical care unit at noon one day and continually so for another 48 hours, and for that interval, ≥≥48 hours had every Riker sedation-agitation scale "4, calm and cooperative," as well as either all Confusion Assessment Method for the Intensive Care Unit scores negative (i.e., no delirium) or Delirium Observation Screening Scale <3 (i.e., no delirium). Each patient was then categorized as having a full one-year follow-up if there was an encounter at our hospital between 12 and 15 months after the last date meeting study inclusion criteria. All follow-up appointments completed within 15 months of the index intensive care unit stay were screened for systematic assessment for psychological and cognitive sequelae of critical illness. RESULTS: From a manual chart review of 366 records, 73 patients were found with follow-up ≥≥12 months. There were 21% (15/73) of the patients assessed for post-intensive care syndrome sequelae (99% confidence interval 10%-35%). CONCLUSIONS: The fact that far fewer than half the patients had documented assessments suggests that retrospective studies should not be used to judge the incidence of post-intensive care syndrome at our hospital. Prospective observational studies would be needed to judge outcomes among critically ill patients with multiple consecutive days of alert and without delirium.

DNA binding drives the association of BRG1/hBRM bromodomains with nucleosomes.

BRG1 and BRM, central components of the BAF (mSWI/SNF) chromatin remodelling complex, are critical in chromatin structure regulation. Here, we show that the human BRM (hBRM) bromodomain (BRD) has moderate specificity for H3K14ac. Surprisingly, we also find that both BRG1 and hBRM BRDs have DNA-binding activity. We demonstrate that the BRDs associate with DNA through a surface basic patch and that the BRD and an adjacent AT-hook make multivalent contacts with DNA, leading to robust affinity and moderate specificity for AT-rich elements. Although we show that the BRDs can bind to both DNA and H3K14ac simultaneously, the histone-binding activity does not contribute substantially to nucleosome targeting in vitro. In addition, we find that neither BRD histone nor DNA binding contribute to the global chromatin affinity of BRG1 in mouse embryonic stem cells. Together, our results suggest that association of the BRG1/hBRM BRD with nucleosomes plays a regulatory rather than targeting role in BAF activity.

Defining Optimal Head-Tilt Position of Resuscitation in Neonates and Young Infants Using Magnetic Resonance Imaging Data.

Head-tilt maneuver assists with achieving airway patency during resuscitation. However, the relationship between angle of head-tilt and airway patency has not been defined. Our objective was to define an optimal head-tilt position for airway patency in neonates (age: 0-28 days) and young infants (age: 29 days-4 months). We performed a retrospective study of head and neck magnetic resonance imaging (MRI) of neonates and infants to define the angle of head-tilt for airway patency. We excluded those with an artificial airway or an airway malformation. We defined head-tilt angle a priori as the angle between occipito-ophisthion line and ophisthion-C7 spinous process line on the sagittal MR images. We evaluated medical records for Hypoxic Ischemic Encephalopathy (HIE) and exposure to sedation during MRI. We analyzed MRI of head and neck regions of 63 children (53 neonates and 10 young infants). Of these 63 children, 17 had evidence of airway obstruction and 46 had a patent airway on MRI. Also, 16/63 had underlying HIE and 47/63 newborn infants had exposure to sedative medications during MRI. In spontaneously breathing and neurologically depressed newborn infants, the head-tilt angle (median ± SD) associated with patent airway (125.3° ± 11.9°) was significantly different from that of blocked airway (108.2° ± 17.1°) (Mann Whitney U-test, p = 0.0045). The logistic regression analysis showed that the proportion of patent airways progressively increased with an increasing head-tilt angle, with > 95% probability of a patent airway at head-tilt angle 144-150°.