Artificial selection reveals complex genetic architecture of shoot branching and its response to nitrate supply in Arabidopsis.

Quantitative traits may be controlled by many loci, many alleles at each locus, and subject to genotype-by-environment interactions, making them difficult to map. One example of such a complex trait is shoot branching in the model plant Arabidopsis, and its plasticity in response to nitrate. Here, we use artificial selection under contrasting nitrate supplies to dissect the genetic architecture of this complex trait, where loci identified by association mapping failed to explain heritability estimates. We found a consistent response to selection for high branching, with correlated responses in other traits such as plasticity and flowering time. Genome-wide scans for selection and simulations suggest that at least tens of loci control this trait, with a distinct genetic architecture between low and high nitrate treatments. While signals of selection could be detected in the populations selected for high branching on low nitrate, there was very little overlap in the regions selected in three independent populations. Thus the regulatory network controlling shoot branching can be tuned in different ways to give similar phenotypes.

Tree architecture: A strigolactone-deficient mutant reveals a connection between branching order and auxin gradient along the tree stem.

Due to their long lifespan, trees and bushes develop higher order of branches in a perennial manner. In contrast to a tall tree, with a clearly defined main stem and branching order, a bush is shorter and has a less apparent main stem and branching pattern. To address the developmental basis of these two forms, we studied several naturally occurring architectural variants in silver birch (Betula pendula). Using a candidate gene approach, we identified a bushy kanttarelli variant with a loss-of-function mutation in the BpMAX1 gene required for strigolactone (SL) biosynthesis. While kanttarelli is shorter than the wild type (WT), it has the same number of primary branches, whereas the number of secondary branches is increased, contributing to its bush-like phenotype. To confirm that the identified mutation was responsible for the phenotype, we phenocopied kanttarelli in transgenic BpMAX1::RNAi birch lines. SL profiling confirmed that both kanttarelli and the transgenic lines produced very limited amounts of SL. Interestingly, the auxin (IAA) distribution along the main stem differed between WT and BpMAX1::RNAi. In the WT, the auxin concentration formed a gradient, being higher in the uppermost internodes and decreasing toward the basal part of the stem, whereas in the transgenic line, this gradient was not observed. Through modeling, we showed that the different IAA distribution patterns may result from the difference in the number of higher-order branches and plant height. Future studies will determine whether the IAA gradient itself regulates aspects of plant architecture.

Children with Congenital Central Hypoventilation Syndrome Do Not Wake up to Ventilator Alarms.

PURPOSE: Congenital Central Hypoventilation Syndrome (CCHS) requires lifelong ventilatory support during sleep. Subjects with CCHS are vulnerable to sleep disturbances associated with treatments, monitoring alarms, and care they receive. We hypothesized that sleep would be disrupted in patients  with CCHS due to ventilatory support and other treatments at night. METHODS: An anonymous survey of patients with CCHS, age up to 17 years was conducted through REDCAP. Subjects were recruited in person, by flyer, email, and social media. Data collected included demographics, PHOX2B genotype, ventilatory support, treatments, nursing, and sleep parameters. RESULTS: We received 23 responses (35% female, 8.1 years ± 5.6). PHOX2B genotypes were 20/24 PARM (2), 20/25 PARM (4), 20/26 PARM (2), 20/27 PARM (9), ≥ 20/28 PARM (2), and NPARM (2). Two subjects did not indicate the PHOX2B genotype. 13/23 were ventilated by PPV via tracheostomy, 7 by NIPPV, 2 by diaphragm pacing, and 1 did not indicate. Additional treatments received at night included suctioning (9), aerosol (1), G-tube feeding (2), and none (11). Only 9 received nursing at night. 13 used pulse oximetry for monitoring, and 9 used both pulse oximetry and end tidal CO2 monitor. 17/23 rarely woke up due to ventilator or monitor alarms. 11/23 usually or sometimes woke up at least once a night; only 2/11 woke up due to alarms. 5/17 who rarely woke up to the alarms had night nursing. CONCLUSION: Most subjects with CCHS did not awaken to ventilator or monitoring alarms and a majority of these patients did not have nighttime nursing. (Mathur et al. in Sleep 43(Supplement_1):A333, 2020).

Natural variation in Arabidopsis shoot branching plasticity in response to nitrate supply affects fitness.

The capacity of organisms to tune their development in response to environmental cues is pervasive in nature. This phenotypic plasticity is particularly striking in plants, enabled by their modular and continuous development. A good example is the activation of lateral shoot branches in Arabidopsis, which develop from axillary meristems at the base of leaves. The activity and elongation of lateral shoots depends on the integration of many signals both external (e.g. light, nutrient supply) and internal (e.g. the phytohormones auxin, strigolactone and cytokinin). Here, we characterise natural variation in plasticity of shoot branching in response to nitrate supply using two diverse panels of Arabidopsis lines. We find extensive variation in nitrate sensitivity across these lines, suggesting a genetic basis for variation in branching plasticity. High plasticity is associated with extreme branching phenotypes such that lines with the most branches on high nitrate have the fewest under nitrate deficient conditions. Conversely, low plasticity is associated with a constitutively moderate level of branching. Furthermore, variation in plasticity is associated with alternative life histories with the low plasticity lines flowering significantly earlier than high plasticity lines. In Arabidopsis, branching is highly correlated with fruit yield, and thus low plasticity lines produce more fruit than high plasticity lines under nitrate deficient conditions, whereas highly plastic lines produce more fruit under high nitrate conditions. Low and high plasticity, associated with early and late flowering respectively, can therefore be interpreted alternative escape vs mitigate strategies to low N environments. The genetic architecture of these traits appears to be highly complex, with only a small proportion of the estimated genetic variance detected in association mapping.

Characterization of sleep habits of children with Sotos syndrome.

Sotos syndrome (SS) is a genetic disorder characterized by accelerated growth in childhood, developmental deficits, and characteristic craniofacial features. While clinicians and parents have reported unusual sleep habits, only one study by Rutter and Cole in 1991 mentioned sleep complaints (Rutter and Cole, Developmental Medicine and Child Neurology, 1991, 33, 898-902). This study aimed to characterize the sleep habits of individuals with SS. We performed a cross-sectional study of individuals with a definite, probable, or possible diagnosis of Sotos syndrome. Participants were asked to complete the Children's Sleep Habits Questionnaire (CHSQ). We compared our data to historical data available from the literature. Subjects with SS showed more sleep disturbance than typically developing individuals (TD), although their sleep onset was less likely to be delayed and their sleep duration was longer. Participants with SS also showed different sleep patterns compared to children with other forms of intellectual and developmental disabilities (IDD). Individuals with SS exhibited early bed and rise times, frequently used transitional objects, displayed repetitive motion at sleep onset, and did not show a decrease in sleep duration with age. The majority of participants fell asleep at the same time each night, in their own bed, and within 20 min, and rarely showed signs of sleepwalking or night terrors. These results improve our understanding of sleep habits of individuals with SS and may be used to guide treatment and provide normalization for children with SS.

Evaluation of Obstructive Sleep Apnea in Prone Versus Nonprone Body Positioning With Polysomnography in Infants With Robin Sequence.

OBJECTIVE: Management of obstructive sleep apnea in infants with Robin sequence (RS) includes prone positioning during sleep, which conflicts with safe infant sleep data. We examined changes in polysomnography (PSG) parameters for prone versus nonprone body positions in these infants. DESIGN: Pre-post interventional, nonblinded study. PARTICIPANTS: Infants with RS referred for PSG were recruited from craniofacial clinic and inpatient units at Children's Hospital Los Angeles, a tertiary pediatric center. Fourteen infants were recruited, and 12 studies were completed on both body positions; 11 studies were used in the analysis. INTERVENTIONS: The PSG was divided into nonprone and prone sleep, moving from their usual sleep position to the other position midway in the study. MAIN OUTCOME MEASURES: Data was collected in each position for obstructive apnea-hypopnea index (oAHI), central apnea index (CAI), sleep efficiency (SE), and arousal index (AI). Signed rank test was used to evaluate the change in body position. RESULTS: All infants were term except 1, age 7 to 218 days (mean: 55 days; standard deviation: 58 days), and 8 (57%) of 14 were female. From nonprone to prone sleep position, the median oAHI (16.0-14.0), CAI (2.9-1.0), and AI (28.0-19.9) decreased (P = .065); SE increased (67.4-85.2; P = .227). CONCLUSIONS: Prone positioning may benefit some infants with RS. However, even those with significant improvement in obstructive sleep apnea did not completely resolve their obstruction. The decision to use prone positioning as a therapy should be objectively evaluated in individual infants.

Congenital Heart Disease in Patients With Cleft Lip/Palate and Its Impact on Cleft Management.

OBJECTIVE: To evaluate characteristics of congenital heart disease (CHD) in patients with cleft lip and/or palate (CL/P) and assess potential associations with cleft outcomes. DESIGN: Retrospective review of all patients with CL/P who underwent primary cleft treatment from 2009 to 2015. SETTING: Children's Hospital Los Angeles, a tertiary hospital. PATIENTS: Exclusion criteria included microform cleft lip diagnosis, international patients, and patients presenting for secondary repair or revision after primary repair at another institution. MAIN OUTCOMES MEASURED: Patient demographics, prenatal and birth characteristics, CL/P characteristics, syndromic status, postoperative complications, and other outcomes were analyzed relative to CHD diagnoses and management. Patients with CL/P with (+CHD) were compared to those without (-CHD) CHD using χ2 tests and analysis of variance. RESULTS: Among 575 patients with CL/P, 83 (14.4%) had CHD. Congenital heart disease rates were significantly higher in patients with cleft palate (CP) compared to other cleft types (χ2, P = .009). Eighty-one (97.6%) out of 83 +CHD patients were diagnosed prior to initial CL/P surgical assessment. Twenty-three (27.7%) +CHD patients required surgical repair of 10 cardiac anomalies prior to cleft care. Congenital heart disease was associated with delayed CP repair and increased rates of fistula in isolated patients with CP. CONCLUSIONS: Congenital heart disease is known to be more prevalent in patients with CL/P. These data suggest the condition is particularly increased in patients with CP. Severe forms of CHD are diagnosed and treated prior to cleft care however postoperative fistula may be more common in patients with CHD. Therefore, careful attention is required for patient optimization and palatal flap dissection in patients with coexisting CHD and CL/P.

SMAX1-LIKE7 Signals from the Nucleus to Regulate Shoot Development in Arabidopsis via Partially EAR Motif-Independent Mechanisms.

Strigolactones (SLs) are hormonal signals that regulate multiple aspects of shoot architecture, including shoot branching. Like many plant hormonal signaling systems, SLs act by promoting ubiquitination of target proteins and their subsequent proteasome-mediated degradation. Recently, SMXL6, SMXL7, and SMXL8, members of the SMAX1-LIKE (SMXL) family of chaperonin-like proteins, have been identified as proteolytic targets of SL signaling in Arabidopsis thaliana However, the mechanisms by which these proteins regulate downstream events remain largely unclear. Here, we show that SMXL7 functions in the nucleus, as does the SL receptor, DWARF14 (D14). We show that nucleus-localized D14 can physically interact with both SMXL7 and the MAX2 F-box protein in a SL-dependent manner and that disruption of specific conserved domains in SMXL7 affects its localization, SL-induced degradation, and activity. By expressing and overexpressing these SMXL7 protein variants, we show that shoot tissues are broadly sensitive to SMXL7 activity, but degradation normally buffers the effect of increasing SMXL7 expression. SMXL7 contains a well-conserved EAR (ETHYLENE-RESPONSE FACTOR Amphiphilic Repression) motif, which contributes to, but is not essential for, SMXL7 functionality. Intriguingly, different developmental processes show differential sensitivity to the loss of the EAR motif, raising the possibility that there may be several distinct mechanisms at play downstream of SMXL7.

Abnormalities in autonomic function in obese boys at-risk for insulin resistance and obstructive sleep apnea.

STUDY OBJECTIVES: Current evidence in adults suggests that, independent of obesity, obstructive sleep apnea (OSA) can lead to autonomic dysfunction and impaired glucose metabolism, but these relationships are less clear in children. The purpose of this study was to investigate the associations among OSA, glucose metabolism, and daytime autonomic function in obese pediatric subjects. METHODS: Twenty-three obese boys participated in: overnight polysomnography; a frequently sampled intravenous glucose tolerance test; and recordings of spontaneous cardiorespiratory data in both the supine (baseline) and standing (sympathetic stimulus) postures. RESULTS: Baseline systolic blood pressure and reactivity of low-frequency heart rate variability to postural stress correlated with insulin resistance, increased fasting glucose, and reduced beta-cell function, but not OSA severity. Baroreflex sensitivity reactivity was reduced with sleep fragmentation, but only for subjects with low insulin sensitivity and/or low first-phase insulin response to glucose. CONCLUSIONS: These findings suggest that vascular sympathetic activity impairment is more strongly affected by metabolic dysfunction than by OSA severity, while blunted vagal autonomic function associated with sleep fragmentation in OSA is enhanced when metabolic dysfunction is also present.

Association between REM sleep and obstructive sleep apnea in obese and overweight adolescents.

PURPOSE: Overweight and obese children have demonstrated reduced rapid eye movement (REM) sleep, affecting energy balance regulation and predisposition to weight gain. Obstructive sleep apnea (OSA) is a known cause of decreased REM sleep. The purpose of this study is to examine the association between the percentage of REM sleep, BMI z-score, and OSA severity in overweight and obese adolescents. METHODS: We performed a cross-sectional study of 92 (43% female) overweight and obese adolescents (13-17 years old) who underwent overnight polysomnography (PSG) at Children's Hospital Los Angeles between 2010 and 2017. RESULTS: The average Body Mass Index (BMI) z-score was 2.27 ± 0.47, with 71% having BMI z-score ≥ 2. REM% during PSG was 15.6 ± 6.8, and obstructive apnea-hypopnea index was 17.1 ± 24.3. The distribution across categories of OSA severity was 27% none (≤ 1.5 events/h), 24% mild (> 1.5-5 events/h), 8% moderate (> 5-10 events/h), and 41% severe (> 10 events/h). REM% was not associated with BMI z-score, either on univariate or multivariate regression with adjustment for age, gender, and apnea-hypopnea index (AHI). When subdivided into OSA categories, a 1-unit increase in BMI z-score was associated with a 5.96 (p = 0.03) increase in REM% in mild OSA and an 8.86 (p = 0.02) decrease in REM% in severe OSA. There was no association between BMI z-score and REM% in none and moderate OSA. CONCLUSION: Among overweight and obese adolescents, BMI z-score was associated with decreased REM% in severe OSA and unexpectedly increased REM% in mild OSA, but there was no association in none or moderate OSA.

Predictors of Failure in Infant Mandibular Distraction Osteogenesis.

PURPOSE: Mandibular distraction osteogenesis (MDO) has been shown to be successful in treating upper airway obstruction caused by micrognathia in pediatric patients. The purpose of this study was to assess the success rate of MDO and possible predictors of failure. PATIENTS AND METHODS: The records of all neonates and infants who underwent MDO from 2008 to 2015 were retrospectively reviewed. Procedural failure was defined as patient death or the need for tracheostomy postoperatively. Details of distraction, length of stay, and failures were captured and elucidated. RESULTS: Of the 82 patients, 47 (57.3%) were male; 46 (56.1%) had sporadic Pierre Robin sequence; 33 (40.3%) had syndromic Pierre Robin sequence; and 3 (3.7%) had micrognathia, not otherwise specified. The average distraction length was 27.5 mm (range, 15 to 30 mm; SD, 4.4 mm), the average age at operation was 63.3 days (range, 3 to 342 days; SD, 71.4 days), and the average length of post-MDO hospital stay was 43 days (range, 9 to 219 days; SD, 35 days) with an average follow-up period of 4.3 years (range, 1.1 to 9.6 years; SD, 2.6 years). There were 7 failures (8.5%) (5 tracheostomies and 2 deaths) resulting in a 91.5% success rate. Regression analysis showed that the predicted probability of the need for tracheostomy was 45% (P = .02) when the patient had a central nervous system (CNS) anomaly. The predicted probability of the need for tracheostomy and death combined was 99.6% when the patient had laryngomalacia and a CNS anomaly and was preoperatively intubated (P < .05). CONCLUSIONS: This review confirms that MDO is an effective method of treating the upper airway obstruction caused by micrognathia with a high success rate. In our sample the presence of CNS abnormalities, laryngomalacia, and preoperative intubation had a significant impact on the failure rate.

Real-time multislice MRI during continuous positive airway pressure reveals upper airway response to pressure change.

PURPOSE: To determine if a real-time magnetic resonance imaging (RT-MRI) method during continuous positive airway pressure (CPAP) can be used to measure neuromuscular reflex and/or passive collapsibility of the upper airway in individual obstructive sleep apnea (OSA) subjects. MATERIALS AND METHODS: We conducted experiments on four adolescents with OSA and three healthy controls, during natural sleep and during wakefulness. Data were acquired on a clinical 3T scanner using simultaneous multislice (SMS) RT-MRI during CPAP. CPAP pressure level was alternated between therapeutic and subtherapeutic levels. Segmented airway area changes in response to rapid CPAP pressure drop and restoration were used to estimate 1) upper airway loop gain (UALG), and 2) anatomical risk factors, including fluctuation of airway area (FAA). RESULTS: FAA significantly differed between OSA patients (2-4× larger) and healthy controls (Student's t-test, P < 0.05). UALG and FAA measurements indicate that neuromuscular reflex and passive collapsibility varied among the OSA patients, suggesting the presence of different OSA phenotypes. Measurements had high intrasubject reproducibility (intraclass correlation coefficient r > 0.7). CONCLUSION: SMS RT-MRI during CPAP can reproducibly identify physiological traits and anatomical risk factors that are valuable in the assessment of OSA. This technique can potentially locate the most collapsible airway sites. Both UALG and FAA possess large variation among OSA patients. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1400-1408.

The Prevalence of Congenital Heart Disease in Nonsyndromic Cleft Lip and/or Palate: A Systematic Review of the Literature.

BACKGROUND: Life-threatening anomalies, such as congenital heart disease (CHD) must be identified in patients with cleft lip and/or palate (CL/P) to minimize perioperative risk. Nevertheless, screening practices vary highly among cleft teams and programs, and little is known about the prevalence and clinical significance of CHD in nonsyndromic CL/P patients. Through a systematic literature review, this study examines the demographics and severity of CHD in the nonsyndromic CL/P population. The implications of concomitant CHD in providing safe and comprehensive cleft care both in the United States and abroad are discussed. METHODS: A systematic review of PubMed literature from 1980 to September 2015 was performed following PRISMA guidelines. Studies describing rates of CHD and severity of lesions specifically in nonsyndromic and all CL/P patients were included. Analysis of cumulative data was performed according to nonsyndromic status and cleft type. RESULTS: Twelve studies were found to meet inclusion criteria. Of the 4055 nonsyndromic CL/P patients who met inclusion criteria, 7.42% (n=301) had CHD, which was significantly greater than the general population (~1%; odds ratio [OR], 7.94; P<0.0001). Congenital heart disease was significantly more common in cleft palate (CP) (OR, 15.1), combined CL and palate (CL+P) (OR, 13.5), and CL (OR, 4.23) compared with the general population. Palatal clefts (CP and CL+P) had significantly increased odds of CHD compared with CL (OR, 3.58 and 3.19, respectively, both P<0.0001). The most common forms of CHD were atrial or ventricular septal defects (n=210, 74.2%), which typically do not require surgical intervention in the general population. Clinical significance of these CHD lesions in CL/P patients is not fully known. CONCLUSIONS: Cleft management programs aim to maximize the number of patients receiving care while maintaining patient safety. Appropriate evaluation of perioperative risk necessitates understanding the prevalence of CHD in CL/P patients and the severity of those lesions. Patients with CL/P, particularly patients with palatal clefts, have significantly higher odds of having CHD than the general population. Congenital heart disease is most likely to present as atrial or ventricular septal defects, which are lesions that are unlikely to impact safety during cleft repair surgery.

Evaluation of upper airway collapsibility using real-time MRI.

PURPOSE: To develop and demonstrate a real-time MRI method for assessing upper airway collapsibility in sleep apnea. MATERIALS AND METHODS: Data were acquired on a clinical 3 Tesla scanner using a radial CAIPIRIHNA sequence with modified golden angle view ordering and reconstructed using parallel imaging and compressed sensing with temporal finite difference sparsity constraint. Segmented airway areas together with synchronized facemask pressure were used to calculate airway compliance and projected closing pressure, Pclose , at four axial locations along the upper airway. This technique was demonstrated in five adolescent obstructive sleep apnea (OSA) patients, three adult OSA patients and four healthy volunteers. Heart rate, oxygen saturation, facemask pressure, and abdominal/chest movements were monitored in real-time during the experiments to determine sleep/wakefulness. RESULTS: Student's t-tests showed that both compliance and Pclose were significantly different between healthy controls and OSA patients (P < 0.001). The results also suggested that a narrower airway site does not always correspond to higher collapsibility. CONCLUSION: With the proposed methods, both compliance and Pclose can be calculated and used to quantify airway collapsibility in OSA with an awake scan of 30 min total scan room time. J. Magn. Reson. Imaging 2016;44:158-167.

A System Analysis of Delay in Outpatient Respiratory Equipment Delivery.

OBJECTIVES: To systematically assess barriers delaying home respiratory equipment requisition and to evaluate for temporal correlation between delays and emergency room or hospitalization episodes. BACKGROUND: Initiation of home respiratory treatments is delayed because of delays in delivery of durable medical equipment (DME). This study assesses root causes of such delays from a system perspective. We also describe clinical consequences by measuring emergency room visits and hospitalization days for temporal correlations. METHODS: We conducted a retrospective review of DME ordering records from April 2011 to March of 2012. SETTINGS: Outpatient DME records in Pediatric Pulmonary Division. RESULTS: Of 164 available orders studied, deliveries were made as followed: 31 (19%) within 24 hr: 18 (59%) oxygen orders and 10 (32%) nebulizer orders 50 (30%) within 1 week: 25 (50%) nebulizer orders and 10 (20%) oxygen orders Delays: 45 (27%) delivered > 1 month: Bilevel positive airway pressure (BPAP) = 16 (36%) Oxygen = 12 (26%) Cough assist device = 7 (16%) Nebulizer = 5 (11%) Miscellaneous devices = 5 (11%) Analysis of barriers includes (a) type of insurance, (b) human error, (c) communication barrier, (d) deficit in training or knowledge, (e) no clear policy, (f) differences in clinical policy/ standard, (g) no DME benefit, (h) no clinical justification, and (i) error in communication/record keeping. Six patients with 7 emergency department (ED) visits and 4 inpatient admissions, totaling 24 hospital days, were temporally associated with delays in delivery of equipment over 30 days. CONCLUSION: One half of commonly used DMEs were delivered within the first week. One quarter of more expensive required more steps for approval. Twenty-nine ED/hospital days with respiratory morbidities were temporally associated with delays.

Functional screening of willow alleles in Arabidopsis combined with QTL mapping in willow (Salix) identifies SxMAX4 as a coppicing response gene.

Willows (Salix spp.) are important biomass crops due to their ability to grow rapidly with low fertilizer inputs and ease of cultivation in short-rotation coppice cycles. They are relatively undomesticated and highly diverse, but functional testing to identify useful allelic variation is time-consuming in trees and transformation is not yet possible in willow. Arabidopsis is heralded as a model plant from which knowledge can be transferred to advance the improvement of less tractable species. Here, knowledge and methodologies from Arabidopsis were successfully used to identify a gene influencing stem number in coppiced willows, a complex trait of key biological and industrial relevance. The strigolactone-related More AXillary growth (MAX) genes were considered candidates due to their role in shoot branching. We previously demonstrated that willow and Arabidopsis show similar response to strigolactone and that transformation rescue of Arabidopsis max mutants with willow genes could be used to detect allelic differences. Here, this approach was used to screen 45 SxMAX1, SxMAX2, SxMAX3 and SxMAX4 alleles cloned from 15 parents of 11 mapping populations varying in shoot-branching traits. Single-nucleotide polymorphism (SNP) frequencies were locus dependent, ranging from 29.2 to 74.3 polymorphic sites per kb. SxMAX alleles were 98%-99% conserved at the amino acid level, but different protein products varying in their ability to rescue Arabidopsis max mutants were identified. One poor rescuing allele, SxMAX4D, segregated in a willow mapping population where its presence was associated with increased shoot resprouting after coppicing and colocated with a QTL for this trait.

Real-time 3D magnetic resonance imaging of the pharyngeal airway in sleep apnea.

PURPOSE: To investigate the feasibility of real-time 3D magnetic resonance imaging (MRI) with simultaneous recording of physiological signals for identifying sites of airway obstruction during natural sleep in pediatric patients with sleep-disordered breathing. METHODS: Experiments were performed using a three-dimensional Fourier transformation (3DFT) gradient echo sequence with prospective undersampling based on golden-angle radial spokes, and L1-norm regularized iterative self-consistent parallel imaging (L1-SPIRiT) reconstruction. This technique was demonstrated in three healthy adult volunteers and five pediatric patients with sleep-disordered breathing. External airway occlusion was used to induce partial collapse of the upper airway on inspiration and test the effectiveness of the proposed imaging method. Apneic events were identified using information available from synchronized recording of mask pressure and respiratory effort. RESULTS: Acceptable image quality was obtained in seven of eight subjects. Temporary airway collapse induced via inspiratory loading was successfully imaged in all three volunteers, with average airway volume reductions of 63.3%, 52.5%, and 33.7%. Central apneic events and associated airway narrowing/closure were identified in two pediatric patients. During central apneic events, airway obstruction was observed in the retropalatal region in one pediatric patient. CONCLUSION: Real-time 3D MRI of the pharyngeal airway with synchronized recording of physiological signals is feasible and may provide valuable information about the sites and nature of airway narrowing/collapse during natural sleep.

Using Arabidopsis to study shoot branching in biomass willow.

The success of the short-rotation coppice system in biomass willow (Salix spp.) relies on the activity of the shoot-producing meristems found on the coppice stool. However, the regulation of the activity of these meristems is poorly understood. In contrast, our knowledge of the mechanisms behind axillary meristem regulation in Arabidopsis (Arabidopsis thaliana) has grown rapidly in the past few years through the exploitation of integrated physiological, genetic, and molecular assays. Here, we demonstrate that these assays can be directly transferred to study the control of bud activation in biomass willow and to assess similarities with the known hormone regulatory system in Arabidopsis. Bud hormone response was found to be qualitatively remarkably similar in Salix spp. and Arabidopsis. These similarities led us to test whether Arabidopsis hormone mutants could be used to assess allelic variation in the cognate Salix spp. hormone genes. Allelic differences in Salix spp. strigolactone genes were observed using this approach. These results demonstrate that both knowledge and assays from Arabidopsis axillary meristem biology can be successfully applied to Salix spp. and can increase our understanding of a fundamental aspect of short-rotation coppice biomass production, allowing more targeted breeding.

Freeman-Sheldon syndrome and respiratory obstruction: a novel use of distraction osteogenesis.

Freeman-Sheldon syndrome, or distal arthrogryposis type IIA (DA 2A), is a rare and severe multiple congenital contracture syndrome that is associated with upper airway obstruction. This obstruction has been clinically significant enough to warrant tracheostomy and has been associated with mortality. We describe a patient who presented to us as a neonate and the novel management of her respiratory obstruction in the setting of DA 2A. Bilateral mandibular osteotomies were performed and bilateral internal mandibular distracters were placed. She was distracted a total of 3 cm over 15 days without event and successfully extubated on the postoperative day 16. Preoperative polysomnogram demonstrated an obstructive apnea hypopnea index of 43.7, but a repeat polysomnogram demonstrated an apnea hypopnea index of 8.1. In this study, we report the first use of distraction osteogenesis in the setting of severe obstructive sleep apnea syndrome secondary to DA 2A.

Sleep disorders in pediatric patients with agenesis of the corpus callosum.

STUDY OBJECTIVES: There is limited information about sleep in agenesis of the corpus callosum (ACC). We aim to describe the sleep architecture and respiratory parameters of children with ACC. METHODS: We performed a retrospective study of 20 patients with ACC who had polysomnography (PSG) between 2000-2023. Demographic data, BMI or weight for length, associated conditions, and PSG findings were collected. National Sleep Foundation (NSF) sleep quality indicators as well as increased PSG arousal index ≥10/h were used in the analysis. Fisher's exact test or unpaired t-test was used to compare groups. RESULTS: Average age was 5.9 ± 5.4 years old; 12/20 patients were male. 6/20 were overweight/obese. 14/20 had complete ACC, and 6/20 had partial ACC. 8/20 had seizures. 15/20 had ≥1 NSF poor sleep quality indicator (decreased SE (45%), decreased REM (53%)) and 9/20 had increased arousals. Between complete and partial ACC, there was no difference in presence of ≥1 poor sleep quality indicator (p= 0.61), SE (p=0.34), REM (p=0.28), and arousals (p=1.0). 11/18 had obstructive sleep apnea (OSA); 5/11 had associated central sleep apnea. There was no difference in OSA between those with complete and partial ACC (p=1.0). OSA was associated with children <3 years old (p=0.01). CONCLUSIONS: Children with ACC have poor sleep quality, and many have OSA. There was no difference in sleep quality or presence of OSA between those with complete and partial ACC. OSA was seen more in younger children. Our study supports the need for screening of sleep-related disorders in patients with ACC.