Risk of failure of adenotonsillectomy for obstructive sleep apnea in obese pediatric patients

INTRODUCTION

Pediatric obesity is a leading risk factor for obstructive sleep apnea (OSA), a condition commonly treated with adenotonsillectomy (T&A). It has been hypothesized that obesity increases a child's risk of failing T&A for OSA, however this relationship has not yet been quantified. The primary objective of this study was to investigate the relationship between obesity as measured by perioperative Body Mass Index (BMI) and persistent OSA following T&A as measured by polysomnography (PSG).

STUDY DESIGN

Retrospective chart review.

METHODS

Pediatric patients who underwent T&A between Jan. 2004 and Jan. 2016 were included. We recruited both obese and non-obese patients to compare caregiver/self reported improvement. Obese patients were recruited from a weight management clinic and included if they had a BMI z-score >1.65 and had pre- and post-operative polysomnograms (PSGs). Control patients included those undergoing T&A for OSA at our institution with BMI <1.65. These patients were age matched to the obese patient population. Age, gender, perioperative BMI z-score, caregiver/self reported improvement, total Apnea-Hypopnea Index (AHI), and O₂ saturation nadir were collected where available. Univariate linear regressions were calculated between perioperative BMI z-score and PSG data.

RESULTS

26 obese study and 47 control subjects were identified for analysis. T&A resulted in statistically significant improvements in total AHI (p = 0.030) and nadir O₂ saturation (p = 0.013) in obese subjects. There was no significant difference between the rate of caregiver/self reported improvement in the two groups. There was a statistically significant correlation between perioperative BMI z-score and the change in total AHI (p = 0.049). Within our population, for every increase by 0.1 in perioperative BMI z-score, the improvement in total AHI post-operatively decreased by 1.63 events/hr. Further, patients with BMI more than 3 standard deviations away from the age-derived normative mean received essentially no benefit from T&A alone.

CONCLUSIONS

Our study established an inverse linear relationship between perioperative BMI z-score and improvement in total AHI with essentially no improvement in patients with BMI z-scores >3. Further studies are required to further elucidate this relationship and investigate the role of additional procedures in the initial management of OSA in obese children.

Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9}  GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5}  GeV to above 10^{11}  GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6}  GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5}  GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.

Distinct subclonal tumour responses to therapy revealed by circulating cell-free DNA

BACKGROUND

The application of precision medicine in oncology requires in-depth characterisation of a patient's tumours and the dynamics of their responses to treatment.

PATIENTS AND METHODS

We used next-generation sequencing of circulating cell-free DNA (cfDNA) to monitor the response of a KIT p.L576P-mutant metastatic vaginal mucosal melanoma to sequential targeted, immuno- and chemotherapy.

RESULTS

Despite a KIT mutation, the response to imatinib was mixed. Unfortunately, tumours were not accessible for molecular analysis. To study the mechanism underlying the mixed clinical response, we carried out whole-exome sequencing and targeted longitudinal analysis of cfDNA. This revealed two tumour subclones; one with a KIT mutation that responded to imatinib and a second KIT-wild-type subclone that did not respond to imatinib. Notably, the subclones also responded differently to immunotherapy. However, both subclones responded to carboplatin/paclitaxel, and although the KIT-wild-type subclone progressed after chemotherapy, it responded to subsequent re-administration of paclitaxel.

CONCLUSION

We show that cfDNA can reveal tumour evolution and subclonal responses to therapy even when biopsies are not available.

Searches for Sterile Neutrinos with the IceCube Detector

The IceCube neutrino telescope at the South Pole has measured the atmospheric muon neutrino spectrum as a function of zenith angle and energy in the approximate 320 GeV to 20 TeV range, to search for the oscillation signatures of light sterile neutrinos. No evidence for anomalous ν_{μ} or ν[over ¯]_{μ} disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data. New exclusion limits are placed on the parameter space of the 3+1 model, in which muon antineutrinos experience a strong Mikheyev-Smirnov-Wolfenstein-resonant oscillation. The exclusion limits extend to sin^{2}2θ_{24}≤0.02 at Δm^{2}∼0.3  eV^{2} at the 90% confidence level. The allowed region from global analysis of appearance experiments, including LSND and MiniBooNE, is excluded at approximately the 99% confidence level for the global best-fit value of |U_{e4}|^{2}.

Spine Cryoablation: Pain Palliation and Local Tumor Control for Vertebral Metastases

BACKGROUND AND PURPOSE

Percutaneous cryoablation has emerged as a minimally invasive technique for the management of osseous metastases. The purpose of this study was to assess the safety and effectiveness of percutaneous imaging-guided spine cryoablation for pain palliation and local tumor control for vertebral metastases.

MATERIALS AND METHODS

Imaging-guided spine cryoablation was performed in 14 patients (31 tumors) with vertebral metastases refractory to conventional chemoradiation therapy or analgesics, to achieve pain palliation and local tumor control in this retrospective study. Spinal nerve and soft-tissue thermal protection techniques were implemented in all ablations. Patient response was evaluated by a pain numeric rating scale administered before the procedure and 1 week, 1 month, and 3 months after the procedure. Pre- and postprocedural analgesic requirements (expressed as morphine-equivalent dosages) were also analyzed at the same time points. Pre- and postprocedural cross-sectional imaging was evaluated in all patients to assess local control (no radiographic evidence of disease at the treated sites). Complications were monitored. Analysis of the primary end points was undertaken via paired-comparison procedures by using the Wilcoxon signed rank test.

RESULTS

Thirty-one tumors were ablated in 14 patients (9 women and 5 men; 20-73 years of age; mean age, 53 years). The most common tumor location was in the lumbar spine (n = 14, 45%), followed by the thoracic spine (n = 8, 26%), sacrum (n = 6, 19%), coccyx (n = 2, 6%), and cervical spine (n = 1, 3%). There were statistically significant decreases in the median numeric rating scale score and analgesic usage at 1-week, 1-month, and 3-month time points (P < .001 for all). Local tumor control was achieved in 96.7% (30/31) of tumors (median follow-up, 10 months). Two patients had transient postprocedural unilateral lower extremity radiculopathy and weakness.

CONCLUSIONS

Percutaneous imaging-guided spine cryoablation is a safe and effective treatment for pain palliation and local tumor control for vertebral metastases.

Evidence of dose saving in routine CT practice using iterative reconstruction derived from a national diagnostic reference level survey

OBJECTIVE

To assess the influence and significance of the use of iterative reconstruction (IR) algorithms on patient dose in CT in Australia.

METHODS

We examined survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS) during 2013 and 2014. We compared median survey dose metrics with categorization by scan region and use of IR.

RESULTS

The use of IR results in a reduction in volume CT dose index of between 17% and 44% and a reduction in dose-length product of between 14% and 34% depending on the specific scan region. The reduction was highly significant (p < 0.001, Wilcoxon rank-sum test) for all six scan regions included in the NDRLS. Overall, 69% (806/1167) of surveys included in the analysis used IR.

CONCLUSION

The use of IR in CT is achieving dose savings of 20-30% in routine practice in Australia. IR appears to be widely used by participants in the ARPANSA NDRLS with approximately 70% of surveys submitted employing this technique.

ADVANCES IN KNOWLEDGE

This study examines the impact of the use of IR on patient dose in CT on a national scale.

Bilateral vestibular schwannomas in older patients: NF2 or chance?

BACKGROUND

Neurofibromatosis type 2 (NF2) is an autosomal dominant condition with high spontaneous mutation rate which predisposes to the development of multiple nerve sheath tumours (schwannomas), meningiomas and ependymoma. The cardinal feature and main diagnostic criterion for the diagnosis of NF2 remains the development of bilateral vestibular schwannoma (BVS). With increasing use of MRI screening the possibility of a 'chance' diagnosis of BVS has been mooted with a potential frequency of one in two million people in their lifetime. Until now, however, no evidence for such an event has been published. We aimed to demonstrate that chance occurrence can occur and to estimate its frequency among those with just BVS late in life.

METHODS

Two vestibular schwannomas from the same patient were DNA sequenced and underwent loss of heterozygosity analysis.

RESULTS

We show that a man who developed BVS, at ages 52 and 67 years developed these tumours sporadically by demonstrating that there were no molecular events in common between the two tumours. Furthermore from a database of over 1200 patients with NF2, we have estimated that ~25% of cases of BVS over 50 years and 50% over 70 years of age where no other features of NF2 are present represent a chance occurrence rather than due to an underlying mosaic or constitutional NF2 mutation.

CONCLUSIONS

Patients presenting with BVS later in life should be appraised of the potential likelihood they may not have NF2 and the resultant further reduction in risks of transmission to offspring.

A chemical and computational approach to comprehensive glycation characterization on antibodies

Non-enzymatic glycation is a challenging post-translational modification to characterize due to the structural heterogeneity it generates in proteins. Glycation has become increasingly recognized as an important product quality attribute to monitor, particularly for the biotechnology sector, which produces recombinant proteins under conditions that are amenable to protein glycation. The elucidation of sites of glycation can be problematic using conventional collision-induced dissociation (CID)-based mass spectrometry because of the predominance of neutral loss ions. A method to characterize glycation using an IgG1 monoclonal antibody (mAb) as a model is reported here. The sugars present on this mAb were derivatized using sodium borohydride chemistry to stabilize the linkage and identified using CID-based MS(2) mass spectrometry and spectral search engines. Quantification of specific glycation sites was then done using a targeted MS(1) based approach, which allowed the identification of a glycation hot spot in the heavy chain complementarity-determining region 3 of the mAb. This targeted approach provided a path forward to developing a structural understanding of the propensity of sites to become glycated on mAbs. Through structural analysis we propose a model in which the number and 3-dimensional distances of carboxylic acid amino acyl residues create a favorable environment for glycation to occur.

Multicenter dose-finding and efficacy and safety outcomes in neonates and children treated with dalteparin for acute venous thromboembolism

BACKGROUND

Low molecular weight heparins (LMWHs) constitute the mainstay of anticoagulant therapy for pediatric venous thromboembolism (VTE). The safety and effectiveness of dalteparin, an LMWH, has not been established in children, and pediatric data on dalteparin for VTE are limited to one single-center experience.

OBJECTIVE

To establish dose-finding (primary endpoint) and efficacy/safety outcomes (secondary endpoints) in children treated with dalteparin in a substudy of the Kids-DOTT trial.

PATIENTS AND METHODS

A prospective multicenter trial using dalteparin subcutaneously twice daily for acute VTE in children aged ≤ 21 years was conducted under an investigator-held Investigational New Drug application registered with the US Food and Drug Administration. Initial weight-based dosing per protocol was as follows: infants (< 12 months), 150 IU kg(-1) ; children (1-12 years), 125 IU kg(-1) ; and adolescents (13-18 years), 100 IU kg(-1) . Bleeding events were categorized according to ISTH criteria. Descriptive non-parametric statistics were employed for all analyses.

RESULTS

Eighteen patients (67% male) were enrolled from January 2010 to October 2013 across four centers. No supratherapeutic levels were observed. Median (range) therapeutic doses by age group were as follows: infants (n = 3), 180 IU kg(-1) (146-181 IU kg(-1) ); children (n = 7), 125 IU kg(-1) (101-175 IU kg(-1) ); and adolescents (n = 8), 100 IU kg(-1) (91-163 IU kg(-1) ). The median duration of dalteparin use was 48 days (range: 2-169 days), and the median follow-up was 10.5 months (range: 2-35 months). There were no related serious adverse events, no clinically relevant bleeding events, and no symptomatic recurrent VTEs.

CONCLUSION

Dalteparin successfully achieved targeted anti-factor Xa levels in 18 children and young adults with acute VTE with a standardized age-based dosing regimen, with a favorable safety and efficacy profile.