Managing magnets: An audit of introduction of the Royal College of Emergency Medicine Best Practice Guideline

AIM

To evaluate management of children and young people presenting to the Emergency Department (ED) with magnet ingestion before and after new guidance.

METHODS

In May 2021, a National Patient Safety Agency and Royal College of Emergency Medicine (RCEM) Best Practice Guideline about management of ingested magnets was published. This was implemented in our department. Children and young people presenting after magnet ingestion were identified from SNOMED (coded routinely collected data) and X-ray requests between January 2016 and March 2022. Management was compared to national guidance.

RESULTS

There were 138 patient episodes of magnet ingestion, with a rising incidence over the 5-year period. Following introduction of the guideline, there was a higher incidence of admission (36% vs. 20%) and operative intervention (15.7% vs. 8%). Use of follow-up X-ray increased from 56% to 90%. There was substantial variation in the management prior to guidance which reduced after introduction of the RCEM guidance.

CONCLUSION

Management of magnet ingestion has become more standardised since introduction of the National RCEM Best Practice Guideline, but there is still room for improvement.

Time-resolved X-ray diffraction diagnostic development for the National Ignition Facility

We present the development of an experimental platform that can collect four frames of x-ray diffraction data along a single line of sight during laser-driven, dynamic-compression experiments at the National Ignition Facility. The platform is comprised of a diagnostic imager built around ultrafast sensors with a 2-ns integration time, a custom target assembly that serves also to shield the imager, and a 10-ns duration, quasi-monochromatic x-ray source produced by laser-generated plasma. We demonstrate the performance with diffraction data for Pb ramp compressed to 150 GPa and illuminated by a Ge x-ray source that produces ∼7 × 1011, 10.25-keV photons/ns at the 400 μm diameter sample.

Transdiagnostic cognitive-behavioral group therapy for anxiety disorders: Therapists’ perception of group management in community-based care

Introduction

Cognitive-behavioral therapy (CBT) is recognized as an effective treatment for anxiety disorders. Transdiagnostic group CBT (tCBT) targets cognitive and behavioural intervention strategies common to anxiety disorders. tCBT allows the treatment of a larger number of patients simultaneously and therapists only need to master a single intervention protocol. However, tCBT may present several challenges for therapists, particularly regarding group management.

Objectives

To explore therapists’ perceptions and experience of group management during tCBT for mixed anxiety disorders.

Methods

A qualitative study embedded in a randomized controlled trial of group tCBT (Roberge & Provencher; CIHR, 2015-2021). Semi-structured interviews were conducted with 18 of the 21 therapists to document their perceptions and to identify improvements for tCBT delivery. The data were analyzed using a deductive approach and based on the interactive cyclical process of data reduction, display and conclusion drawing.

Results

Therapists raised the challenge of the heterogeneous characteristics of participants’ anxious profile, since they had to be creative to provide exercises that were suitable for a whole group. Exposure exercises, a key component of tCBT, were particularly affected by the composition of the groups. Previous group animation experience and the ability to establish a therapeutic alliance from a group perspective were important facilitators. Co-therapy also facilitated the intervention, since it allowed the therapists to be more vigilant to group dynamics and favored the organization of tCBT.

Conclusions

This study highlights the importance of exploring therapists’ perceptions and experience about group management in order to identify facilitators and barriers of group tCBT in community-based care.

Disclosure

No significant relationships.

457 The Effect of Biochemical Adversity of Primary Hyperparathyroidism on Preoperative Imaging (SPECT-CT and US Parathyroids)

Aim

Primary hyperparathyroidism (PHPT) is a common endocrine disorder, with an estimated incidence of 1/500 women and 1/2000 men older than 40 years. Several factors influence the positivity of preoperative scans including serum calcium, PTH and vitamin D levels, and gland size. The aim of our study is to examine the effect of biochemical adversity of primary hyperparathyroidism on preoperative imaging (SPECT-CT and US parathyroids).

Method

Retrospective study of 176 parathyroidectomies (2017-2020) in a tertiary referral centre with biochemistry, SPECT-CT, US parathyroids and histology outcomes being recorded. Failed parathyroidectomies were excluded.

Results

Patients were divided into 4 groups based on the preoperative calcium levels (normocalcemia <2.6, 3.4%; mild 2.60-2.79, 51.1%; moderate 2.80-2.99, 31.2%; severe >3.0 mmol/l, 14.2% of patients). Age (p-0.0297), preoperative vitamin D (p-0.03) and PTH levels (p-0.0001) were different while SPECT-CT positivity (p-0.29) weight of gland (p-0.015) and US positivity (p-0.09) were similar within the subgroups. Looking at the whole group, patients with positive SPECT-CT have a larger weight (p < 0.0001) while preoperative PTH levels was higher for the positive SPECT-CT patients (p-0.0289). No relation was identified between calcium levels and SPECT-CT positivity (p-0.18). No significance between preoperative vitamin D and positivity of US and SPECT-CT within the study group were noted.

Conclusions

Serum PTH levels and weight of the gland are directly correlated with positivity of preoperative imaging. Preoperative calcium and vitamin D levels correlates indirectly with the severity of the disease but did not influence the preoperative imaging positivity.

Upgrade of the gated laser entrance hole imager G-LEH-2 on the National Ignition Facility

A major upgrade has been implemented for the ns-gated laser entrance hole imager on the National Ignition Facility (NIF) to obtain high-quality data for Hohlraum physics study. In this upgrade, the single "Furi" hCMOS sensor (1024 × 448 pixel arrays with two-frame capability) is replaced with dual "Icarus" sensors (1024 × 512 pixel arrays with four-frame capability). Both types of sensors were developed by Sandia National Laboratories for high energy density physics experiments. With the new Icarus sensors, the new diagnostic provides twice the detection area with improved uniformity, wider temporal coverage, flexible timing setup, and greater sensitivity to soft x rays (<2 keV). These features, together with the fact that the diagnostic is radiation hardened and can be operated on the NIF for high neutron yield deuterium-triterium experiments, enable significantly greater return of data per experiment.

Incidental finding of cornea verticillata or lamellar inclusions in kidney biopsy: measurement of lyso-Gb3 in plasma defines between Fabry disease and drug-induced phospholipidosis

INTRODUCTION

Therapy with cationic amphiphilic drugs (Amiodarone or hydroxychloroquine) may result in biochemically and ultrastructurally similar lipid inclusions in many cells also affected by Fabry disease (FD). In addition, it often results in similar clinical manifestations such as cornea verticillata. This may lead to a FD misdiagnosis, especially when a complete medical history is not available to the ophthalmologist confronted with cornea verticillata or to the pathologist examining a kidney biopsy. When enzymatic/genetic test or pathological studies are not conclusive, a specific biomarker may help clarify this dilemma. The plasma globotriaosylsphingosine (lyso-Gb3) assay has high sensitivity and specificity and is elevated above normal levels in FD.

MATERIALS AND METHODS

We measured plasma lyso-Gb3 levels in male patients receiving Amiodarone or hydroxychloroquine and compared it with male patients with classic and late onset variant of FD.

RESULTS

In all Fabry patients (classic and late onset variant) α-GalA activity was deficient in dried blood spot and plasma lyso-Gb3 was above normal levels. Patients on treatment with Amiodarone or hydroxychloroquine had normal values for α-GalA activity and lyso-Gb3 in plasma.

CONCLUSIONS

Even when Amiodarone or hydroxychloroquine may decrease α-GalA activity in vitro or in cell culture, our results showed that in all patients lyso-Gb3 plasma levels remain normal with no evidence of reduction in α-GalA activity, confirming the specificity of this biomarker for the diagnosis of FD.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

How does gatekeeper training improve suicide prevention for elderly people in nursing homes? A controlled study in 24 centres

Background

The death rate due to suicide in elderly people is particularly high. As part of suicide selective prevention measures for at-risk populations, the WHO recommends training “gatekeepers”.

Methods

In order to assess the impact of gatekeeper training for members of staff, we carried out a controlled quasi-experimental study over the course of one year, comparing 12 nursing homes where at least 30% of the staff had undergone gatekeeper training with 12 nursing homes without trained staff. We collected data about the residents considered to be suicidal, their management further to being identified, as well as measures taken at nursing home level to prevent suicide.

Results

The two nursing home groups did not present significantly different characteristics. In the nursing homes with trained staff, the staff were deemed to be better prepared to approach suicidal individuals. The detection of suicidal residents relied more on the whole staff and less on the psychologist alone when compared to nursing homes without trained staff. A significantly larger number of measures were taken to manage suicidal residents in the trained nursing homes. Suicidal residents were more frequently referred to the psychologist. Trained nursing homes put in place significantly more suicide prevention measures at an institutional level.

Conclusions

Having trained gatekeepers has an impact not only for the trained individuals but also for the whole institution where they work, both in terms of managing suicidal residents and routine suicide prevention measures.

Surface manipulation of a curved polycyclic aromatic hydrocarbon-based nano-vehicle molecule equipped with triptycene wheels

With a central curved chassis, a four-wheeled molecule-vehicle was deposited on a Au(111) surface and imaged at low temperature using a scanning tunneling microscope. The curved conformation of the chassis and the consequent moderate interactions of the four wheels with the surface were observed. The dI/dV constant current maps of the tunneling electronic resonances close to the Au(111) Fermi level were recorded to identify the potential energy entry port on the molecular skeleton to trigger and control the driving of the molecule. A lateral pushing mode of molecular manipulation and the consequent recording of the manipulation signals confirm how the wheels can step-by-step rotate while passing over the Au(111) surface native herringbone reconstructions. Switching a phenyl holding a wheel to the chassis was not observed for triggering a lateral molecular motion inelastically and without any mechanic push by the tip apex. This points out the necessity to encode the sequence of the required wheels action on the profile of the potential energy surface of the excited states to be able to drive a molecule-vehicle.

Development of whole brain versus targeted dentate gyrus irradiation model to explain low to moderate doses of exposure effects in mice

Evaluation of the consequences of low to moderate doses of ionizing radiation (IR) remains a societal challenge, especially for children exposed to CT scans. Appropriate experimental models are needed to improve scientific understanding of how exposure of the postnatal brain to IR affects behavioral functions and their related pathophysiological mechanisms, considering brain complex functional organization. In the brain, the dorsal and ventral hippocampal dentate gyrus can be involved in distinct major behavioral functions. To study the long term behavioral effects of brain exposure at low to moderate doses of IR (doses range 0.25–1 Gy), we developed three new experimental models in 10-day-old mice: a model of brain irradiation and two targeted irradiation models of the dorsal and ventral dentate gyrus. We used the technological properties of the SARRP coupled with MR imaging. Our irradiation strategy has been twofold endorsed. The millimetric ballistic specificity of our models was first validated by measuring gamma-H2AX increase after irradiation. We then demonstrated higher anxiety/depressive-like behavior, preferentially mediate by the ventral part of the dentate gyrus, in mice after brain and ventral dentate gyrus IR exposure. This work provides new tools to enhance scientific understanding of how to protect children exposed to IR.

The impact of direct-acting antiviral agents on liver and kidney transplant costs and outcomes

Direct-acting antiviral medications (DAAs) have revolutionized care for hepatitis C positive (HCV+) liver (LT) and kidney (KT) transplant recipients. Scientific Registry of Transplant Recipients registry data were integrated with national pharmaceutical claims (2007-2016) to identify HCV treatments before January 2014 (pre-DAA) and after (post-DAA), stratified by donor (D) and recipient (R) serostatus and payer. Pre-DAA, 18% of HCV+ LT recipients were treated within 3 years and without differences by donor serostatus or payer. Post-DAA, only 6% of D-/R+ recipients, 19.8% of D+/R+ recipients with public insurance, and 11.3% with private insurance were treated within 3 years (P < .0001). LT recipients treated for HCV pre-DAA experienced higher rates of graft loss (adjusted hazard ratio [aHR] _1.34 1.85_2.10 , P < .0001) and death (aHR _1.47 1.68_1.91 , P < .0001). Post-DAA, HCV treatment was not associated with death (aHR _0.34 0.67_1.32 , P = .25) or graft failure (aHR _0.32 0.64_1.26 , P = .20) in D+R+ LT recipients. Treatment increased in D+R+ KT recipients (5.5% pre-DAA vs 12.9% post-DAA), but did not differ by payer status. DAAs reduced the risk of death after D+/R+ KT by 57% (_0.19 0.43_0.95 , P = .04) and graft loss by 46% (_0.27 0.54_1.07 , P = .08). HCV treatment with DAAs appears to improve HCV+ LT and KT outcomes; however, access to these medications appears limited in both LT and KT recipients.

[Post-traumatic pulmonary aspergilloma]

INTRODUCTION

Aspergillomas occur due to colonization of a pre-existing pulmonary, bronchial or pleural cavity by Aspergillus spp. Often asymptomatic, this pathology can reveal itself by recurrent haemoptysis or when bacterial superinfections occur. Aspergillomas occurring in post-traumatic cavities are rare and their management is poorly codified.

CASE REPORT

A child suffered from a chest wound at the age of 13 years. Two years later, investigation of recurrent haemoptysis revealed a residual pneumatocele in the right lower lobe colonized by Aspergillus spp. Initial treatment with systemic azole antifungals was unsuccessful because of digestive and ophthalmological intolerance. Surgical treatment by right lower lobectomy was finally decided on by the multidisciplinary team. This revealed an intrabronchial foreign body of vegetal type with cellulosic reinforcement, causing a polymorphic granulomatous reaction around, and associated with a proliferation of filamentous fungi including Aspergillus fumigatus. Surgery was followed by liposomal amphotericin B treatment for three weeks with a favourable outcome.

CONCLUSIONS

This clinical case illustrates the benefits of surgical management of post-traumatic aspergillomas, even in children, in order to eradicate the aspergillus implant and to remove any foreign body to prevent recurrence.

Using Ultrapure Water in Hemodialysis Delays Carpal Tunnel Syndrome

Since 1977, our patients have undergone chronic HD with ultra-pure dialysate (UPD), defined as having endotoxin levels below 0.008 ng/ml and less than 1 bacteria/ml of dialysate. We evaluated the incidence of carpal tunnel syndrome (CTS) in three groups of patients. Group I (GI), 84 patients, dialysed for 6.1 ± 3.2 years (mean ± SD) with UPD only; Group II (GII), 39 patients, first dialysed for 3.7 ± 2.3 years with non-UPD and afterwards for 8.4 ± 2.1 years with UPD; Group III (G III), 103 patients treated for 6 ± 5.9 years exclusively with non-UPD. All patients were dialysed with cuprophan or cellulose acetate membranes.

Results, expressed by Kaplan-Meier actuarial survival curves as the percent of patients without CTS, show that CTS occurred significantly less in GI than in GIII. This may be due to less stimulation of monocytes resulting from the absence of bacteria, endotoxins and pyrogens in the dialysate which would reduce the stimulation of cytokines release, interleukin 1 and 6, and tumor necrosis factor, known to stimulate β2 microglobulin synthesis.

[The use of the Debriefing Assessment for Simulation in Healthcare (DASH) in a simulation-based team learning program for newborn resuscitation in the delivery room]

OBJECTIVE

To evaluate the contribution of the Debriefing Assessment for Simulation in Healthcare (DASH, Centre for Medical Simulation, Harvard) in a high-fidelity simulation in situ program used for newborn resuscitation training.

METHODS

The DASH was scored by trainees and instructors at the end of the session. The instructors' feedback and opinions were collected.

RESULTS

The study included 16 training sessions (ten maternity units) with 156 trainees and ten instructors (45 DASH). The mean DASH score was rated at 6.6/7 by the learners and 5.4/7 by the instructors. For each element, the instructors scored the DASH lower than the learners (P<0.001). For each session, the instructors' DASH scores were lower than the learners' score (P<0.001). The instructors' DASH scores progressed during the first three sessions of the study. The instructors evaluated the DASH's usefulness at 3.6/7 in self-evaluation and at 6.3/7 if used collectively.

CONCLUSION

The trainees evaluated the debriefing with high-level DASH scores, thus validating the educational aim of the program. In contrast, the instructors' DASH scores were lower and heterogeneous. Debriefing high-fidelity simulations remains a complex exercise. The use of the DASH can be a helpful measure for instructors in regard of their own practice. Its main advantage could be in providing a validated tool that will allow a "debriefing of debriefing".

[Type 1 neurofibromatosis: Onset of two tumors before the age of 5years]

Neurofibromatosis type 1 (NF1) is a frequent autosomal dominant genetic disorder that predisposes to the development of benign and malignant tumors. Mutation of the NF1 gene affects the RAS-MAPK signaling pathway and leads to a dysfunction in cell proliferation and induces tumor development. Epidemiology of cancer in children with NF1 is very different from the general pediatric population, which requires regular and specific monitoring. Neurofibroma is the most frequent benign tumor. It can be very invalidating depending on the size and location of the tumor. Currently, there is no specific treatment for these tumors. The most frequent malignancies in children with NF1 are leukemias, rhabdomyosarcomas, malignant peripheral nerve sheath tumors and gliomas. The treatment of these tumors should consider the risk of second cancers induced by radio- and chemotherapy. We report on the case of a 5-year-old boy with NF1 developing two tumors.

[Recommendations for imaging neonatal ischemic stroke]

Neuroimaging is critical for the diagnosis of neonatal arterial ischemic stroke (NAIS) and for prognosis estimation. The purpose of this work is to define guidelines of clinical neuroimaging for the diagnosis of NAIS, for the optimization of the imaging timing and for the assessment of the prognostic value of each imaging technique. A systematic search of electronic databases (Medline via Pubmed) for studies whose title and abstract were focused on NAIS has been conducted. One hundred and ten articles were selected and their results were analyzed by three Senior Practitioners of pediatric radiology using common methodology for guidelines elaboration within the group of experts gathered by Scientific Societies in the field. MRI with a diffu si on-weighted sequence (DWI) and T1, T2, and T2*-weighted sequences must be performed in the case of suspected NAIS (no sedation is required). In the first hours after the injury, an acute ischemic lesion is characterized by a hypersignal on the diffusion-weighted sequence, with a decrease of the apparent coefficient of diffusion (ADC). The best time to evaluate the extent of the ischemic lesion is between day 2 and day 4 after injury, when the ADC decrease reaches its nadir. In the acute phase, US may be useful as first imaging at the bedside to exclude other pathologies like large space-occupying hemorrhages, but its specific added value on NAIS diagnosis or prognosis assessment is very low. CT scan has no added value in NAIS, compared to MRI. Motor outcome is correlated with the extent of the lesion and with the presence of a definite injury of the corticospinal tract, which is well seen on the diffusion sequence at the acute stage. A secondary atrophy within the mesencephalon (cerebral peduncles) is tied in with a high risk of hemiplegia. Visual outcome is more often compromised in the case of lesions of the posterior cerebral artery territory.

Nasal glial heterotopia or congenital hemangioma? A case report

Nasal glial heterotopia (NGH) is a rare benign tumor of the median line. We describe the case of a child presenting a lateral nasal mass. The characteristics of the prenatal ultrasound and the postnatal clinical examination argued in favor of a congenital hemangioma (CH). The MRI performed at 6 weeks of life suggested glial heterotopia. This diagnosis was confirmed by the pathological analysis. Congenital hemangiomas and nasal glial heterotopies have similar clinical presentations. Prenatal ultrasound diagnosis between NGH and CH is difficult. Fetal MRI is not yet highly specific for these two lesions, but it can eliminate an intracerebral connection in cases of NGH. Postnatal exams are more specific. Flow on the Doppler exam is rapid for CH and slow for NGH. On MRI, these two lesions appear as a hypersignal on T2-weighted sequences, but less intense for NGH than for CH. Distinguishing between NGH and CH can be difficult. This does not have a direct incidence on treatment because it is surgical in both cases.

Chronic intestinal pseudo-obstruction. Did you search for lysosomal storage diseases?

Chronic intestinal pseudo-obstruction results in clinical manifestations that resemble intestinal obstruction but in the absence of any physical obstructive process. Fabry disease is an X-linked lysosomal storage disease characterized by the dysfunction of multiple systems, including significant gastrointestinal involvement. We report the occurrence of chronic intestinal pseudo-obstruction in two unrelated patients with Fabry disease and the possible explanation of a direct relation of these two disorders. In Fabry disease, gastrointestinal symptoms occur in approximately 70% of male patients, but the frequency ranges from 19% to 69% in different series. In some patients, colonic dysmotility due glycolipid deposition in autonomic plexus and ganglia can lead to the pseudo-obstruction syndrome, simulating intestinal necrosis. That is why up to this date colostomy has been performed in some cases, even for children with FD without cardiac, renal or cerebrovascular compromise. Early treatment with enzyme replacement therapy in asymptomatic or mildly symptomatic patients may be justified in order to prevent disease progression. Several studies have demonstrated that enzyme replacement therapy alleviates GI manifestations. Because of the non-specific nature of the gastrointestinal symptoms, diagnosis of Fabry disease is often delayed for several years. Gastrointestinal involvement is often misdiagnosed or under-reported. It is therefore very important to consider Fabry disease in the differential diagnosis of chronic intestinal pseudo-obstruction.

[Metastatic medullary thyroid carcinoma in a child with multiple endocrine neoplasia 2B. Efficiency of medium-term treatment with vandetanib without thyroid surgery]

Medullary thyroid carcinoma (MTC) is a rare cancer during childhood. MTC is sporadic in approximately 80% of cases and hereditary in 20%. When hereditary, it can be associated with other endocrine neoplasias and/or typical nonendocrine diseases, thus configuring the multiple endocrine neoplasia (MEN) syndromes. Children with clinically obvious MTC belong to MEN 2A or 2B families, related to RET mutations. The standard treatment is total thyroidectomy and central neck dissection. However, treatment of advanced MTC has not yet been standardized, even if a new tyrosine kinase inhibitor specific to RET mutation has changed the outcome of such patients. Vandetanib plays a role in the treatment of children with metastatic, locally advanced and nonoperable MTC, with good tolerance. We report the 5-year treatment of an 11-year-old patient, with vandetanib and without thyroid surgery.

[Bacillus Calmette-Guérin osteomyelitis. A case report in a former preterm baby]

Postvaccination osteo-articular mycobacterial infectious disease is a rare and potentially serious complication after Bacillus Calmette-Guérin (BCG) vaccine. We report on a case of a former preterm baby born at 30 weeks of gestation who was vaccinated with BCG Copenhagen strain at 2 months of age. He presented 6 months later with a painful limp, which was found to be a mono-articular osteitis of the right ankle. Histology of the biopsy showed signs of mycobacterial infection and molecular analysis confirmed a BCG infection. Blood tests did not reveal any immunodeficiency associated with the disease (IFN-gamma levels were normal). The course of the disease was favorable with 9 months of antibiotic therapy against mycobacteria. BCG complications should lead to screening for immunodeficiency. The prognosis of BCG osteitis is excellent if the disease is localized. No link between prematurity and BCG complications has been found to date. BCG vaccination of premature infant should be the same as for the general population.

Investigation of Photovoltaic Properties of Single Core-Shell GaN/InGaN Wires

We report the investigation of the photovoltaic properties of core-shell GaN/InGaN wires. The radial structure is grown on m-plane {11̅00} facets of self-assembled c̅-axis GaN wires elaborated by metal-organic vapor phase epitaxy (MOVPE) on sapphire substrates. The conversion efficiency of wires with radial shell composed of thick In0.1Ga0.9N layers and of 30× In0.18Ga0.82N/GaN quantum wells are compared. We also investigate the impact of the contact nature and layout on the carrier collection and photovoltaic performances. The contact optimization results in an improved conversion efficiency of 0.33% and a fill factor of 83% under 1 sun (AM1.5G) on single wires with a quantum well-based active region. Photocurrent spectroscopy demonstrates that the response ascribed to the absorption of InGaN/GaN quantum wells appears at wavelengths shorter than 440 nm.

Experimental and theoretical analysis of transport properties of core-shell wire light emitting diodes probed by electron beam induced current microscopy

We report a systematic experimental and theoretical investigation of core-shell InGaN/GaN single wire light-emitting diodes (LEDs) using electron beam induced current (EBIC) microscopy. The wires were grown by catalyst-free MOVPE and processed into single wire LEDs using electron beam lithography on dispersed wires. The influence of the acceleration voltage and of the applied bias on the EBIC maps was investigated. We show that the EBIC maps provide information both on the minority carrier effects (i.e. on the local p-n junction collection efficiency) and on the majority carrier effects (i.e. the transport efficiency from the excited region toward the contacts). Because of a finite core and shell resistance a non-negligible current redistribution into the p-n junction takes place during the majority carrier transport. A theoretical model for transport in a core-shell wire is developed, allowing to explain the dependence of the EBIC profiles on the experimental parameters (the electron beam acceleration voltage and the bias applied on the device) and on the structural parameters of the wire (core and shell resistance, shunt resistance, etc). Comparison between simulated and experimental profiles provides valuable information concerning the structure inhomogeneities and gives insight into the wire electrical parameters.

Integrated photonic platform based on InGaN/GaN nanowire emitters and detectors

We report the fabrication of a photonic platform consisting of single wire light-emitting diodes (LED) and photodetectors optically coupled by waveguides. MOVPE-grown (metal-organic vapor-phase epitaxy) InGaN/GaN p-n junction core-shell nanowires have been used for device fabrication. To achieve a good spectral matching between the emission wavelength and the detection range, different active regions containing either five narrow InGaN/GaN quantum wells or one wide InGaN segment were employed for the LED and the detector, respectively. The communication wavelength is ∼400 nm. The devices are realized by means of electron beam lithography on Si/SiO2 templates and connected by ∼100 μm long nonrectilinear SiN waveguides. The photodetector current trace shows signal variation correlated with the LED on/off switching with a fast transition time below 0.5 s.

Currarino Syndrome and HPE Microform Associated with a 2.7-Mb Deletion in 7q36.3 Excluding SHH Gene

Holoprosencephaly (HPE) is the most common forebrain defect in humans. It results from incomplete midline cleavage of the prosencephalon and can be caused by environmental and genetic factors. HPE is usually described as a continuum of brain malformations from the most severe alobar HPE to the middle interhemispheric fusion variant or syntelencephaly. A microform of HPE is limited to craniofacial features such as congenital nasal pyriform aperture stenosis and single central maxillary incisor, without brain malformation. Among the heterogeneous causes of HPE, point mutations and deletions in the SHH gene at 7q36 have been identified as well as extremely rare chromosomal rearrangements in the long-range enhancers of this gene. Here, we report a boy with an HPE microform associated with a Currarino syndrome. Array CGH detected a de novo 2.7-Mb deletion in the 7q36.3 region including the MNX1 gene, usually responsible for the Currarino triad but excluding SHH, which is just outside the deletion. This new case provides further evidence of the importance of the SHH long-range enhancers in the HPE spectrum.

Spica cast as an alternative to general anesthesia for lower limb MRI in young children

Background

The conventional approach for MRI procedures in very young children is to use general anesthesia which comes with inherent risks. Non-pharmacological strategies to reduce anxiety in children have also been described, but they all require patient cooperation. The purpose of the study was to evaluate the ability to complete diagnosis using temporary spica cast immobilization (TSCI) in children less than 3 years old undergoing MRI procedures for lower limb disorders.

Materials and methods

A retrospective review identified 14 children under 3 years old that had required an MRI for a lower limb disorder, using TSCI. The MRI procedure was performed for evaluation of hip dysplasia, bone infections, limping, evaluation of soft tissue tumor and femoral head osteonecrosis. A spica cast was fitted by the pediatric orthopedic team. The MRI procedure was subsequently performed.

Results

Diagnosis was achieved in all cases. The radiologist identified movement artifacts (14 %) that did not impair the image quality enough to prevent interpretation.

Conclusion

TSCI is a safe, effective and costless procedure avoiding general anesthesia for young patients under 3 years old who require MRI for pelvis or lower limb disorders.

Level of evidence

IV.

New roles of SHOX as regulator of target genes

The homeobox gene SHOX encodes a transcription factor which is important for normal limb development. Approximately 5 to 10% of short patients exhibit a mutation or deletion in either the SHOX gene or its downstream enhancer regions. In humans, SHOX deficiency has been associated with various short stature syndromes as well as non-syndromic idiopathic short stature. A common feature of these syndromes is disproportionate short stature with a particular shortening of the forearms and lower legs. Madelung deformity, cubitus valgus, high-arched palate and muscular hypertrophy also differed markedly between patients with or without SHOX gene defects. A clinical trial in patients with SHOX deficiency and Turner syndrome demonstrated highly significant growth hormone-stimulated increases in height velocity and height SDS in both groups. Employing microarray analyses and cell culture experiments, a strong effect of SHOX on the expression of the natriuretic peptide BNP and the fibroblast growth factor receptor gene FGFR3 could be demonstrated. We found that BNP was positively regulated, while Fgfr3 was negatively regulated by SHOX. A regulation that occurs mainly in the mesomelic segments, a region where SHOX is known to be strongly expressed, offers a possible explanation for the phenotypes seen in patients with FGFR3 (e.g. achondroplasia) and SHOX defects (e.g. Léri-Weill dyschondrosteosis).