Glutathione depletion and increased apoptosis rate in human cystinotic proximal tubular cells

We have determined levels of glutathione (GSH), ATP, mitochondrial complex activity and apoptosis rate in proximal tubular cells (PTCs) exfoliated from urine in cystinotic (n=9) and control (n=9) children. Intracellular GSH was significantly depleted in cystinotic PTCs compared with controls (6.8nmol GSH/mg protein vs 11.8nmol GSH/mg protein; P<0.001), but there were no significant differences in mitochondrial complex activities or ATP levels under basal conditions. Cystinotic PTCs showed significantly increased apoptosis rate. After PTCs had been stressed by hypoxia, there was further depletion of GSH in cystinotic and control PTCs (2.4nmol GSH/mg protein vs 7.2nmol GSH/mg protein; P<0.001). Hypoxic stress led to increased complexI and complexIV activities in control but not in cystinotic PTCs. ATP levels were significantly reduced in cystinotic PTCs after hypoxic stress (12.2nmol/mg protein vs 26.9nmol/mg protein; P<0.001). GSH depletion occurs in this in vitro model of cystinotic PTCs, is exaggerated by hypoxic stress and may contribute to reduced ATP and failure to increase complexI/IV activities. Apoptotic rate is also increased, and these mechanisms may contribute to cellular dysfunction in cultured, human cystinotic PTC

Sustained Efficacy and Safety of Burosumab, a Monoclonal Antibody to FGF23, in Children With X-Linked Hypophosphatemia

PURPOSE: In X-linked hypophosphatemia (XLH), excess fibroblast growth factor-23 causes hypophosphatemia and low calcitriol, leading to musculoskeletal disease with clinical consequences. XLH treatment options include conventional oral phosphate with active vitamin D, or monotherapy with burosumab, a monoclonal antibody approved to treat children and adults with XLH. We have previously reported outcomes up to 64 weeks, and here we report safety and efficacy follow-up results up to 160 weeks from an open-label, multicenter, randomized, dose-finding trial of burosumab for 5- to 12-year-old children with XLH. METHODS: After 1 week of conventional therapy washout, patients were randomized 1:1 to burosumab every 2 weeks (Q2W) or every 4 weeks (Q4W) for 64 weeks, with dosing titrated based on fasting serum phosphorus levels between baseline and week 16. From week 66 to week 160, all patients received Q2W burosumab. RESULTS: Twenty-six children were randomized initially into each Q2W and Q4W group and all completed treatment to week 160. In 41 children with open distal femoral and proximal tibial growth plates (from both treatment groups), total Rickets Severity Score significantly decreased by 0.9 ± 0.1 (least squares mean ± SE; P < 0.0001) from baseline to week 160. Fasting serum phosphorus increases were sustained by burosumab therapy throughout the study, with an overall population mean (SD) of 3.35 (0.39) mg/dL, within the pediatric normal range (3.2-6.1 mg/dL) at week 160 (mean change from baseline P < 0.0001). Most adverse events were mild to moderate in severity. MAIN CONCLUSIONS: In children with XLH, burosumab administration for 160 weeks improved phosphate homeostasis and rickets and was well-tolerated. Long-term safety was consistent with the reported safety profile of burosumab. CLINICALTRIALS.GOV: NCT0216357

Conservative treatment for uncomplicated appendicitis in children:the CONTRACT feasibility study, including feasibility RCT

Background Whilst non-operative treatment is known to be effective for the treatment of uncomplicated acute appendicitis in children, comparative randomised trial data reporting important outcomes compared to appendicectomy are lacking.ObjectivesTo ascertain the feasibility of conducting a multi-centre randomised controlled trial (RCT) testing the effectiveness and cost-effectiveness of a non-operative treatment pathway compared to appendicectomy for the treatment of uncomplicated acute appendicitis in children.•DesignMixed methods study including: a feasibility RCT; embedded and parallel qualitative and survey studies; parallel health economic feasibility study; development of a core outcome set.Setting Three specialist NHS Paediatric Surgical Units in EnglandParticipants Children (aged 4-15 years) clinically diagnosed with uncomplicated acute appendicitis participated in the feasibility RCT. Children, their families, recruiting clinicians and other healthcare professionals involved in caring for children with appendicitis took part in the qualitative study. UK Specialist Paediatric Surgeons took part in the survey. Specialist Paediatric Surgeons, Adult General Surgeons who treat children, and children and young people who previously had appendicitis along with their families took part in the core outcomes set development.Interventions Participants in the feasibility RCT were randomised to a non-operative treatment pathway (broad-spectrum antibiotics and active observation) or appendicectomy.Main outcome measures Primary outcome measure was the proportion of eligible patients recruited to the feasibility trial.Data sourcesNHS casenotes, questionnaire responses, transcribed audio recordings of recruitment discussions and qualitative interviewsResults Overall, 50% (95%CI 40-59) of 115 eligible participants approached about the trial agreed to participate and were randomised. There was high acceptance of randomisation and good adherence to trial procedures and follow-up (follow rates of 89%, 85% and 85% at six weeks, three months and six months respectively). More participants had perforated appendicitis than had been anticipated.Qualitative work enabled us to: communicate about the trial effectively with patients and families; design and deliver bespoke training to optimise recruitment; and understand how to optimise design and delivery of a future trial.The health economic study, indicated that the main cost drivers are the ward stay cost and the cost of the operation, and has informed quality of life assessment methods for future work.A core outcome set for the treatment of uncomplicated acute appendicitis in children and young people was developed, containing 14 outcomes.There is adequate surgeon interest to justify proceeding to an effectiveness trial with 51% of those surveyed expressing a willingness to recruit with an unchanged trial protocol.LimitationsSince the feasibility RCT was only performed in three centres we cannot guarantee successful recruitment across a larger number of sites. However, our qualitative work has informed a bespoke training package to facilitate this. Although survey results suggest adequate clinician interest to make a larger trial possible, actual participation may differ, and equipoise may have moved over time.Conclusions A future effectiveness trial is feasible following limited additional preparation to establish appropriate outcome measures and case identification. We recommend a limited package of qualitative work be included to optimise recruitment at new centres in particular.Future work Prior to proceeding to an effectiveness trial we need to: develop a robust method for distinguishing children with uncomplicated acute appendicitis from those with more advanced appendicitis; reach agreement on a primary outcome measure and effect size that is acceptable to all stakeholder groups involved.Study registration ISRCTN15830435.Funding detailsNIHR HTA programm

CONTRACT Study - CONservative TReatment of Appendicitis in Children (feasibility):study protocol for a randomised controlled Trial

BackgroundCurrently, the routine treatment for acute appendicitis in the United Kingdom is an appendicectomy. However, there is increasing scientific interest and research into non-operative treatment of appendicitis in adults and children. While a number of studies have investigated non-operative treatment of appendicitis in adults, this research cannot be applied to the paediatric population. Ultimately, we aim to perform a UK-based multicentre randomised controlled trial (RCT) to test the clinical and cost effectiveness of non-operative treatment of acute uncomplicated appendicitis in children, as compared with appendicectomy. First, we will undertake a feasibility study to assess the feasibility of performing such a trial.Methods/designThe study involves a feasibility RCT with a nested qualitative research to optimise recruitment as well as a health economic substudy. Children (aged 4–15 years inclusive) diagnosed with acute uncomplicated appendicitis that would normally be treated with an appendicectomy are eligible for the RCT. Exclusion criteria include clinical/radiological suspicion of perforated appendicitis, appendix mass or previous non-operative treatment of appendicitis. Participants will be randomised into one of two arms. Participants in the intervention arm are treated with antibiotics and regular clinical assessment to ensure clinical improvement. Participants in the control arm will receive appendicectomy. Randomisation will be minimised by age, sex, duration of symptoms and centre. Children and families who are approached for the RCT will be invited to participate in the embedded qualitative substudy, which includes recording of recruitment consultants and subsequent interviews with participants and non-participants and their families and recruiters. Analyses of these will inform interventions to optimise recruitment. The main study outcomes include recruitment rate (primary outcome), identification of strategies to optimise recruitment, performance of trial treatment pathways, clinical outcomes and safety of non-operative treatment. We have involved children, young people and parents in study design and delivery.DiscussionIn this study we will explore the feasibility of performing a full efficacy RCT comparing non-operative treatment with appendicectomy in children with acute uncomplicated appendicitis. Factors determining success of the present study include recruitment rate, safety of non-operative treatment and adequate interest in the future RCT. Ultimately this feasibility study will form the foundation of the main RCT and reinforce its design.Trial registrationISRCTN15830435. Registered on 8 February 2017

Adaptor protein-2 sigma subunit mutations causing familial hypocalciuric hypercalcaemia type 3 (FHH3) demonstrate genotype-phenotype correlations, codon bias and dominant-negative effects

The adaptor protein-2 sigma subunit (AP2σ2) is pivotal for clathrin-mediated endocytosis of plasma membrane constituents such as the calcium-sensing receptor (CaSR). Mutations of the AP2σ2 Arg15 residue result in familial hypocalciuric hypercalcaemia type 3 (FHH3), a disorder of extracellular calcium (Ca(2+) o) homeostasis. To elucidate the role of AP2σ2 in Ca(2+) o regulation, we investigated 65 FHH probands, without other FHH-associated mutations, for AP2σ2 mutations, characterized their functional consequences and investigated the genetic mechanisms leading to FHH3. AP2σ2 mutations were identified in 17 probands, comprising 5 Arg15Cys, 4 Arg15His and 8 Arg15Leu mutations. A genotype-phenotype correlation was observed with the Arg15Leu mutation leading to marked hypercalcaemia. FHH3 probands harboured additional phenotypes such as cognitive dysfunction. All three FHH3-causing AP2σ2 mutations impaired CaSR signal transduction in a dominant-negative manner. Mutational bias was observed at the AP2σ2 Arg15 residue as other predicted missense substitutions (Arg15Gly, Arg15Pro and Arg15Ser), which also caused CaSR loss-of-function, were not detected in FHH probands, and these mutations were found to reduce the numbers of CaSR-expressing cells. FHH3 probands had significantly greater serum calcium (sCa) and magnesium (sMg) concentrations with reduced urinary calcium to creatinine clearance ratios (CCCR) in comparison with FHH1 probands with CaSR mutations, and a calculated index of sCa × sMg/100 × CCCR, which was ≥ 5.0, had a diagnostic sensitivity and specificity of 83 and 86%, respectively, for FHH3. Thus, our studies demonstrate AP2σ2 mutations to result in a more severe FHH phenotype with genotype-phenotype correlations, and a dominant-negative mechanism of action with mutational bias at the Arg15 residue

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. I. Identifying and Characterizing the Protostellar Content of the OMC-2 FIR4 and OMC-2 FIR3 Regions

We present ALMA (0.87~mm) and VLA (9~mm) observations toward OMC2-FIR4 and OMC2-FIR3 within the Orion integral-shaped filament that are thought to be the nearest regions of intermediate mass star formation. We characterize the continuum sources within these regions on $\sim$40~AU (0\farcs1) scales and associated molecular line emission at a factor of $\sim$30 better resolution than previous observations at similar wavelengths. We identify six compact continuum sources within OMC2-FIR4, four in OMC2-FIR3, and one additional source just outside OMC2-FIR4. This continuum emission is tracing the inner envelope and/or disk emission on less than 100~AU scales. HOPS-108 is the only protostar in OMC2-FIR4 that exhibits emission from high-excitation transitions of complex organic molecules (e.g., methanol and other lines) coincident with the continuum emission. HOPS-370 in OMC2-FIR3 with L~$\sim$~360~\lsun, also exhibits emission from high-excitation methanol and other lines. The methanol emission toward these two protostars is indicative of temperatures high enough to thermally evaporate methanol from icy dust grains; overall these protostars have characteristics similar to hot corinos. We do not identify a clear outflow from HOPS-108 in \twco, but find evidence of interaction between the outflow/jet from HOPS-370 and the OMC2-FIR4 region. The multitude of observational constraints indicate that HOPS-108 is likely a low to intermediate-mass protostar in its main mass accretion phase and it is the most luminous protostar in OMC2-FIR4. The high resolution data presented here are essential for disentangling the embedded protostars from their surrounding dusty environments and characterizing them

StaR Child Health: developing evidence-based guidance for the design, conduct and reporting of paediatric trials

There has been a huge upsurge in clinical research in children in the last decade, stimulated in England by dedicated research infrastructure and support through the National Institute for Health Research. This infrastructure offering research design, expert review, trial management, research nurse, data support and dedicated facilities enables paediatricians to conduct more and better research. The challenge is how to design and conduct trials that will make a real difference to children's health. Standards for Research (StaR) in Child Health was founded in 2009 to address the paucity and shortcomings of paediatric clinical trials. This global initiative involves methodologists, clinicians, patient advocacy groups and policy makers dedicated to developing practical, evidence-based standards for enhancing the reliability and relevance of paediatric clinical research. In this overview, we highlight the contribution of StaR to this agenda, describe the international context, and suggest how StaR's future plans could be integrated with new and existing support for researc

A family With hyponatremia and the nephrogenic syndrome of inappropriate antidiuresis

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD) is an X-linked disorder caused by activating mutations in arginine vasopressin receptor 2 (AVPR2), resulting in persistently concentrated urine. We report on a family affected by NSIAD with the known mutation R137C, an arginine to cysteine substitution at amino acid 137. The spectrum of symptoms varied markedly and ranged from infrequent voiding to incidentally noted hyponatremia to recurrent admissions with hyponatremic seizures. There was evidence for physiologic compensatory mechanisms: most affected members intuitively compensated for the concentrated urine by curtailing their fluid intake. Before the genetic diagnosis, these members had recognized each other by their infrequent voiding, which especially suited one patient, a London cab driver. Interestingly, after water deprivation, urine osmolality was significantly lower in patients compared with unaffected members, suggesting desensitization of the downstream signaling pathway with persistent AVPR2 activation. Urine osmolality was as low as 241 mOsm/kg (241 mmol/kg) in patients, which could obfuscate the diagnosis. The development of symptoms of hyponatremia was strikingly different in the 2 male patients: one patient was asymptomatic with a plasma sodium level of 120 mEq/L (120 mmol/L), whereas another experienced seizures with similar values. Investigations of such genetically defined patients show clues for the understanding of human physiology and inform diagnosis and clinical management

Renal Phenotype in Lowe Syndrome: A Selective Proximal Tubular Dysfunction

Background and objectives: Lowe syndrome is defined by congenital cataracts, mental retardation, and proximal tubulopathy and is due to mutations in OCRL. Recently, mutations in OCRL were found to underlie some patients with Dent disease, characterized by low molecular weight proteinuria, hypercalciuria, and nephrocalcinosis. This phenotypic heterogeneity is poorly understood