Modeling the one-dimensional imager of neutrons (ODIN) for neutron response functions at the Sandia Z facility

The one-dimensional imager of neutrons (ODIN) at the Sandia Z facility consists of a 10-cm block of tungsten with rolled edges, creating a slit imager with slit widths of either 250, 500, or 750 μm. Designed with a 1-m neutron imaging line of sight, we achieve about 4:1 magnification and 500-μm axial spatial resolution. The baseline inertial confinement fusion concept at Sandia is magnetized liner inertial fusion, which nominally creates a 1-cm line source of neutrons. ODIN was designed to determine the size, shape, and location of the neutron producing region, furthering the understanding of compression quality along the cylindrical axis of magnetized liner implosions. Challenges include discriminating neutrons from hard x-rays and gammas with adequate signal-to-noise in the 2 × 10¹² deuterium-deuterium (DD) neutron yield range, as well as understanding the point spread function of the imager to various imaging detectors (namely, CR-39). Modeling efforts were conducted with MCNP6.1 to determine neutron response functions for varying configurations in a clean DD neutron environment (without x-rays or gammas). Configuration alterations that will be shown include rolled-edge slit orientation and slit width, affecting the resolution and response function. Finally, the experiment to determine CR-39 neutron sensitivity, with and without a high density polyethylene (n, p) converter, an edge spread function, and resolution will be discussed.

Average neutron time-of-flight instrument response function inferred from single D-T neutron events within a plastic scintillator

The apparent ion temperature and neutron-reaction history are important characteristics of a fusion plasma. Extracting these quantities from a measured neutron-time-of-flight signal requires accurate knowledge of the instrument response function (IRF). This work describes a novel method for obtaining the IRF directly for single DT neutron interactions by utilizing n-alpha coincidence. The t(d,α)n nuclear reaction was produced at Sandia National Laboratories' Ion Beam Laboratory using a 300 keV Cockcroft-Walton generator to accelerate a 2.5 μA beam of 175 keV D⁺ ions into a stationary ErT₂ target. The average neutron IRF was calculated by taking a time-corrected average of individual neutron events within an EJ-228 plastic scintillator. The scintillator was coupled to two independent photo-multiplier tubes operated in the current mode: a Hamamatsu 5946 mod-5 and a Photek PMT240. The experimental setup and results will be discussed.

A proposal for a new PhD level curriculum on quantitative methods for drug development

This paper provides an overview of "Improving Design, Evaluation and Analysis of early drug development Studies" (IDEAS), a European Commission-funded network bringing together leading academic institutions and small- to large-sized pharmaceutical companies to train a cohort of graduate-level medical statisticians. The network is composed of a diverse mix of public and private sector partners spread across Europe, which will host 14 early-stage researchers for 36 months. IDEAS training activities are composed of a well-rounded mixture of specialist methodological components and generic transferable skills. Particular attention is paid to fostering collaborations between researchers and supervisors, which span academia and the private sector. Within this paper, we review existing medical statistics programmes (MSc and PhD) and highlight the training they provide on skills relevant to drug development. Motivated by this review and our experiences with the IDEAS project, we propose a concept for a joint, harmonised European PhD programme to train statisticians in quantitative methods for drug development.

Coronary heart disease mortality in treated familial hypercholesterolaemia: Update of the UK Simon Broome FH register

BACKGROUND AND AIMS

Patients with familial hypercholesterolaemia (FH) have an elevated risk of coronary heart disease (CHD). Here we compare changes in CHD mortality in patients with heterozygous (FH) pre 1992, before lipid-lowering therapy with statins was used routinely, and in the periods 1992-2008 and 2008-2016.

METHODS

1903 Definite (DFH) and 1650 Possible (PFH) patients (51% women) aged 20-79 years, recruited from 21 lipid clinics in the United Kingdom and followed prospectively between 1980 and 2016 for 67,060 person-years. The CHD standardised mortality ratio (SMR) compared to the population in England and Wales was calculated (with 95% Confidence intervals).

RESULTS

There were 585 deaths, including 252 from CHD. Overall, the observed 2.4-fold excess coronary mortality for treated DFH post-1991 was significantly higher than the 1.78 excess for PFH (35% 95% CI 3%-76%). In patients with DFH and established coronary disease, there was a significant excess coronary mortality in all time periods, but in men it was reduced from a 4.83-fold excess (2.32-8.89) pre-1992 to 4.66 (3.46-6.14) in 1992-2008 and 2.51 (1.01-5.17) post-2008, while in women the corresponding values were 7.23 (2.65-15.73), 4.42 (2.70-6.82) and 6.34 (2.06-14.81). Primary prevention in men with DFH resulted in a progressive reduction in coronary mortality over the three time-periods, with no excess mortality evident post-2008 (0.89 (0.29-2.08)), although in women the excess persisted (post-2008 3.65 (1.75-6.72)).

CONCLUSIONS

The results confirm the benefit of statin treatment in reducing CHD mortality, but suggest that FH patients with pre-existing CHD and women with FH may not be treated adequately.

Ultrasound-guided adductor canal block: a cadaver study investigating the effect of a thigh tourniquet

BACKGROUND

Placement of local anaesthetic within the adductor canal using ultrasonography is an alternative to femoral nerve blocks for postoperative pain relief after knee joint replacement surgery. However, the effect of an inflated thigh tourniquet on the distribution of local anaesthetic within the adductor canal is unknown. The aim of this cadaveric study was to compare the distribution of radio-opaque dye within the adductor canal in the presence or absence of an inflated thigh tourniquet.

METHODS

Bilateral ultrasound-guided adductor canal blocks were performed on the thawed lower limbs of five fresh frozen human cadavers. The left and right lower cadaver limbs were randomised to receive or not receive a thigh tourniquet inflated to 300 mm Hg for 1 h. X-rays with iohexol radio-opaque dye were obtained in four views, and fiducial markers inserted as reference points. Virtual editing technology was used to recreate outlines representing the distribution of the radio-opaque dye and superimpose these on anatomical images.

RESULTS

Radio-opaque dye was distributed on the medial aspect of the thighs with entire and well circumscribed margins. The majority of the radio-opaque dye was confined within the adductor canal. Superior-inferior dye distribution was 315 mm [95% confidence intervals (CI) 289-342] and 264 mm (95% CI 239-289) in the presence and absence of an inflated thigh tourniquet, respectively (diff 95% CI -80.46 to -22.22, P=0.0081). Image analysis using the recreated radio-opaque outlines suggested that the most proximal point of the radio-opaque dye was 100 mm (95% CI 82-117) or 117 mm (95% CI 62-171) below the inguinal ligament in the presence and absence of an inflated thigh tourniquet, respectively (diff 95% CI -38 to 72, P=0.456).

CONCLUSIONS

Application and inflation of thigh tourniquets significantly increased the combined superior-inferior dye distribution within the adductor canal of cadaveric limbs. There was insufficient evidence to suggest significant proximal spread of 25 ml of local anaesthetic to involve the motor branches of the femoral nerve. In some patients, the local anaesthetic may reach the popliteal fossa in close approximation to the sciatic nerve.

A Phase II Study of Pembrolizumab in EGFR-Mutant, PD-L1+, Tyrosine Kinase Inhibitor Naïve Patients With Advanced NSCLC

BACKGROUND

Despite the significant antitumor activity of pembrolizumab in NSCLC, clinical benefit has been less frequently observed in patients whose tumors harbor EGFR mutations compared to EGFR wild-type patients. Our single-center experience on the KEYNOTE-001 trial suggested that pembrolizumab-treated EGFR-mutant patients, who were tyrosine kinase inhibitor (TKI) naïve, had superior clinical outcomes to those previously treated with a TKI. As TKI naïve EGFR-mutants have generally been excluded from pembrolizumab studies, data to guide treatment decisions in this patient population is lacking, particularly in patients with programmed death ligand 1 (PD-L1) expression ≥50%.

METHODS

We conducted a phase II trial (NCT02879994) of pembrolizumab in TKI naive patients with EGFR mutation-positive, advanced NSCLC and PD-L1-positive (≥1%, 22C3 antibody) tumors. Pembrolizumab was administered 200 mg every 3 weeks. The primary endpoint was objective response rate. Secondary endpoints included safety of pembrolizumab, additional pembrolizumab efficacy endpoints, and efficacy and safety of an EGFR TKI after pembrolizumab.

RESULTS

Enrollment was ceased due to lack of efficacy after 11 of 25 planned patients were treated. Eighty-two percent of trial patients were treatment naïve, 64% had sensitizing EGFR mutations, and 73% had PD-L1 expression ≥50%. Only 1 patient had an objective response (9%), but repeat analysis of this patient's tumor definitively showed the original report of an EGFR mutation to be erroneous. Observed treatment-related adverse events were similar to prior experience with pembrolizumab, but two deaths within 6 months of enrollment, including one attributed to pneumonitis, were of concern.

CONCLUSIONS

Pembrolizumab's lack of efficacy in TKI naïve, PD-L1+, EGFR-mutant patients with advanced NSCLC, including those with PD-L1 expression ≥50%, suggests that it is not an appropriate therapeutic choice in this setting.

In vivo growth and genomic characterization of rickettsia-like organisms isolated from farmed Chinook salmon (Oncorhynchus tshawytscha) in New Zealand

A rickettsia-like organism, designated NZ-RLO2, was isolated from Chinook salmon (Oncorhynchus tshawytscha) farmed in the South Island, New Zealand. In vivo growth showed NZ-RLO2 was able to grow in CHSE-214, EPC, BHK-21, C6/36 and Sf21 cell lines, while Piscirickettsia salmonis LF-89T grew in all but BHK-21 and Sf21. NZ-RLO2 grew optimally in EPC at 15°C, CHSE-214 and EPC at 18°C. The growth of LF-89 T was optimal at 15°C, 18°C and 22°C in CHSE-24, but appeared less efficient in EPC cells at all temperatures. Pan-genome comparison of predicted proteomes shows that available Chilean strains of P. salmonis grouped into two clusters (p-value = 94%). NZ-RLO2 was genetically different from previously described NZ-RLO1, and both strains grouped separately from the Chilean strains in one of the two clusters (p-value = 88%), but were closely related to each other. TaqMan and Sybr Green real-time PCR targeting RNA polymerase (rpoB) and DNA primase (dnaG), respectively, were developed to detect NZ-RLO2. This study indicates that the New Zealand strains showed a closer genetic relationship to one of the Chilean P. salmonis clusters; however, more Piscirickettsia genomes from wider geographical regions and diverse hosts are needed to better understand the classification within this genus.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

The evolution of practical radiobiological modelling

A summary of the key aspects of radiobiological modelling is provided, based on the theoretical and practical concepts of the linear quadratic model, which gradually replaced other numerical approaches. The closely related biological effective dose concept is useful in many clinical applications. Biological effective dose formulations in conventional photon-based radiotherapy continue to be developed, and can be extended to the now increasingly used proton and ion-beam therapy, to very low or high dose ranges, the dose rate effect, hypoxia and repopulation. Such established and new research developments will be of interest to clinicians, physicists and biologists to better understand the processes underlying radiotherapy and assist their collaborative efforts to make radiotherapy safer and more effective.