High-magnification Faraday rotation imaging and analysis of X-pinch implosion dynamics

An X-pinch load driven by an intense current pulse (>100 kA in ∼100 ns) can result in the formation of a small radius, runaway compressional micro-pinch. A micro-pinch is characterized by a hot (>1 keV), current-driven (>100 kA), high-density plasma column (near solid density) with a small neck diameter (1-10 µm), a short axial extent (<1 mm), and a short duration (≲1 ns). With material pressures often well into the multi-Mbar regime, a micro-pinch plasma often radiates an intense, sub-ns burst of sub-keV to multi-keV x rays. A low-density coronal plasma immediately surrounding the dense plasma neck could potentially shunt current away from the neck and thus reduce the magnetic drive pressure applied to the neck. To study the current distribution in the coronal plasma, a Faraday rotation imaging diagnostic (1064 nm) capable of producing simultaneous high-magnification polarimetric and interferometric images has been developed for the MAIZE facility at the University of Michigan. Designed with a variable magnification (1-10×), this diagnostic achieves a spatial resolution of ∼35 µm, which is useful for resolving the ∼100-μm-scale coronal plasma immediately surrounding the dense core. This system has now been used on a reduced-output MAIZE (100-200 kA, 150 ns) to assess the radial distribution of drive current immediately surrounding the dense micro-pinch neck. The total current enclosed was found to increase as a function of radius, r, from a value of ≈50±25 kA at r ≈ 140 µm (at the edge of the dense neck) to a maximal value of ≈150±75 kA for r ≥ 225 µm. This corresponds to a peak magnetic drive pressure of ≈75±50 kbar at r ≈ 225 µm. The limitations of these measurements are discussed in the paper.

No life-history cost of tebufenozide resistance in the smaller tea tortrix moth

BACKGROUND

Tebufenozide is widely used to control populations of the smaller tea tortrix, Adoxophyes honmai. However, A. honmai has evolved resistance such that straightforward pesticide application is an untenable long-term approach for population control. Evaluating the fitness cost of resistance is key to devising a management strategy that slows the evolution of resistance.

RESULTS

We used three approaches to assess the life-history cost of tebufenozide resistance with two strains of A. honmai: a tebufenozide-resistant strain recently collected from the field in Japan and a susceptible strain that has been maintained in the laboratory for decades. First, we found that the resistant strain with standing genetic variation did not decline in resistance in the absence of insecticide over four generations. Second, we found that genetic lines that spanned a range of resistance profiles did not show a negative correlation between their LD₅₀ , the dosage at which 50 % of individuals died, and life-history traits that are correlates of fitness. Third, we found that the resistant strain did not manifest life-history costs under food limitation. Our crossing experiments indicate that the allele at an ecdysone receptor locus known to confer resistance explained much of the variance in resistance profiles across genetic lines.

CONCLUSION

Our results indicate that the point mutation in the ecdysone receptor, which is widespread in tea plantations in Japan, does not carry a fitness cost in the tested laboratory conditions. The absence of a cost of resistance and the mode of inheritance have implications for which strategies may be effective in future resistance management efforts. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Estimating the aquatic risk from exposure to up to twenty-two pesticide active ingredients in waterways discharging to the Great Barrier Reef

Pesticides decrease the quality of water reaching the Great Barrier Reef (GBR), Australia. Up to 86 pesticide active ingredients (PAIs) were monitored between July 2015 to end of June 2018 at 28 sites in waterways that discharge to the GBR. Twenty-two frequently detected PAIs were selected to calculate their combined risk when they co-occur in water samples. Species sensitivity distributions (SSDs) for the 22 PAIs to fresh and marine species were developed. The SSDs, the multi-substance potentially affected fraction (msPAF) method, Independent Action model of joint toxicity and a Multiple Imputation method were combined to convert measured PAI concentration data to estimates of the Total Pesticide Risk for the 22 PAIs (TPR₂₂) expressed as the average percentage of species affected during the wet season (i.e., 182 days). The TPR₂₂ and percent contribution of active ingredients of Photosystem II inhibiting herbicides, Other Herbicides, and Insecticides to the TPR₂₂ were estimated. The TPR₂₂ ranged from <1 % to 42 % of aquatic species being affected. Approximately 85 % of the TPR₂₂ estimates were >1 % - meaning they did not meet the Reef 2050 Water Quality Improvement Plan's pesticide target for waters entering the GBR. There were marked spatial differences in TPR₂₂ estimates - regions dominated by grazing had lower estimates while those with sugar cane tended to have higher estimates. On average, active ingredients of PSII herbicides contributed 39 % of the TPR₂₂, the active ingredients of Other Herbicides contributed ~36 % and of Insecticides contributed ~24 %. Nine PAIs (diuron, imidacloprid, metolachlor, atrazine, MCPA, imazapic, metsulfuron, triclopyr and ametryn) were responsible for >97 % of TPR₂₂ across all the monitored waterways.

Perpendicular Subcritical Shock Structure in a Collisional Plasma Experiment

We present a study of perpendicular subcritical shocks in a collisional laboratory plasma. Shocks are produced by placing obstacles into the supermagnetosonic outflow from an inverse wire array z pinch. We demonstrate the existence of subcritical shocks in this regime and find that secondary shocks form in the downstream. Detailed measurements of the subcritical shock structure confirm the absence of a hydrodynamic jump. We calculate the classical (Spitzer) resistive diffusion length and show that it is approximately equal to the shock width. We measure little heating across the shock (<10% of the ion kinetic energy) which is consistent with an absence of viscous dissipation.

Investigation of Mitochondrial Related Variants in a Cerebral Small Vessel Disease Cohort

Monogenic forms of cerebral small vessel disease (CSVD) can be caused by both variants in nuclear DNA and mitochondrial DNA (mtDNA). Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is known to have a phenotype similar to Cerebral Autosomal Dominant Arteriopathy with Sub-cortical Infarcts and Leukoencephalopathy (CADASIL), and can be caused by variants in the mitochondrial genome and in several nuclear-encoded mitochondrial protein (NEMP) genes. The aim of this study was to screen for variants in the mitochondrial genome and NEMP genes in a NOTCH3-negative CADASIL cohort, to identify a potential link between mitochondrial dysfunction and CSVD pathology. Whole exome sequencing was performed for 50 patients with CADASIL-like symptomology on the Ion Torrent system. Mitochondrial sequencing was performed using an in-house designed protocol with sequencing run on the Ion GeneStudio S5 Plus (S5 +). NEMP genes and mitochondrial sequencing data were examined for rare (MAF < 0.001), non-synonymous variants that were predicted to have a deleterious effect on the protein. We identified 29 candidate NEMP variants that had links to either MELAS-, encephalopathy-, or Alzheimer’s disease–related phenotypes. Based on these changes, variants affecting POLG, MTO1, LONP1, NDUFAF6, NDUFB3, and TCIRG1 were thought to play a potential role in CSVD pathology in this cohort. Overall, the exploration of the mitochondrial genome identified a potential role for mitochondrial related proteins and mtDNA variants contributing to CSVD pathologies.

Molecular Imaging and the PD-L1 Pathway: From Bench to Clinic

Programmed death-1 (PD-1) and programmed death ligand 1 (PD-L1) inhibitors target the important molecular interplay between PD-1 and PD-L1, a key pathway contributing to immune evasion in the tumor microenvironment (TME). Long-term clinical benefit has been observed in patients receiving PD-(L)1 inhibitors, alone and in combination with other treatments, across multiple tumor types. PD-L1 expression has been associated with response to immune checkpoint inhibitors, and treatment strategies are often guided by immunohistochemistry-based diagnostic tests assessing expression of PD-L1. However, challenges related to the implementation, interpretation, and clinical utility of PD-L1 diagnostic tests have led to an increasing number of preclinical and clinical studies exploring interrogation of the TME by real-time imaging of PD-(L)1 expression by positron emission tomography (PET). PET imaging utilizes radiolabeled molecules to non-invasively assess PD-(L)1 expression spatially and temporally. Several PD-(L)1 PET tracers have been tested in preclinical and clinical studies, with clinical trials in progress to assess their use in a number of cancer types. This review will showcase the development of PD-(L)1 PET tracers from preclinical studies through to clinical use, and will explore the opportunities in drug development and possible future clinical implementation.

An imaging refractometer for density fluctuation measurements in high energy density plasmas

We report on a recently developed laser-probing diagnostic, which allows direct measurements of ray-deflection angles in one axis while retaining imaging capabilities in the other axis. This allows us to measure the spectrum of angular deflections from a laser beam, which passes through a turbulent high-energy-density plasma. This spectrum contains information about the density fluctuations within the plasma, which deflect the probing laser over a range of angles. We create synthetic diagnostics using ray-tracing to compare this new diagnostic with standard shadowgraphy and schlieren imaging approaches, which demonstrates the enhanced sensitivity of this new diagnostic over standard techniques. We present experimental data from turbulence behind a reverse shock in a plasma and demonstrate that this technique can measure angular deflections between 0.06 and 34 mrad, corresponding to a dynamic range of over 500.

Multiple deprivation and geographic distance to community physical activity events - achieving equitable access to parkrun in England

Objectives

To evaluate geographic access to free weekly outdoor physical activity events (‘parkrun’) in England, with a particular focus on deprived communities, and to identify optimal locations for future events to further maximise access.

Study design

This study is a cross-sectional ecological analysis of the socio-economic disparities in geographic access to parkrun events in England in late 2018.

Methods

We combined geolocation data on all English Lower Layer Super Output Areas and parkrun events to calculate geodesic distances to the nearest event for more than 32,000 communities in England. We use this measure of geographic access to summarise the relationship between access and socio-economic deprivation, measured using the index of multiple deprivation. We then used geographic coordinates of public green spaces in England to conduct a simple location-allocation analysis to identify 200 locations for future event locations that would maximise access.

Results

In England, 69% of the population live within 5 km of one of the 465 parkrun events. There is a small negative correlation between distance and deprivation, indicating that access is slightly better in more socio-economically deprived areas. Setting up an additional 200 events in optimal locations would improve access: the average distance to the nearest parkrun event would improve by 1.22 km, from 4.65 km to 3.43 km, and approximately 82% of the English population would live within 5 km of a parkrun event.

Conclusion

Over two-thirds of the English population live within 5 km of a parkrun event, and contrary to our expectation, we find that geographic access is slightly better for those living in more deprived communities. Creating additional events may improve geographic access, but effective strategies will still be needed to increase engagement in new and existing events by those living in socio-economically deprived areas.

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Parkrun in a grass-roots movement that organises free weekly 5 km running and walking events.

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In England, the median distance to the nearest parkrun event was 3.4 km; 69% of the population lived within 5 km of an event.

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Access showed no negative socio-economic gradient. In fact, people in deprived communities had better geographic access.

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Sport England provided funding to set up 200 new events. We identified optimal locations, to further maximise public access.

Analysis of pesticide mixtures discharged to the lagoon of the Great Barrier Reef, Australia

Organisms and ecosystems are generally exposed to mixtures of chemicals rather than to individual chemicals, but there have been relatively few detailed analyses of the mixtures of pesticides that occur in surface waters. This study examined over 2600 water samples, analysed for between 21 and 47 pesticides, from 15 waterways that discharge to the lagoon of the Great Barrier Reef in Queensland, Australia between July 1, 2011 and June 30, 2015. Essentially all the samples (99.8%) contained detectable concentrations (>limit of detection) of pesticides and pesticide mixtures. Approximately, 10% of the samples contained no quantifiable (>limit of reporting) pesticides, 10% contained one quantifiable pesticide and 80% contained quantifiable mixtures of 2-20 pesticides. Approximately 82% of samples that contained quantifiable mixtures had more than two modes of action (MoAs), but only approximately 6% had five or more MoAs. The mode, average and median number of quantifiable pesticides in all the samples were 2, 5.1 and 4, respectively. The most commonly detected compounds both individually and in mixtures were the pesticides atrazine, diuron, imidacloprid, hexazinone, 2,4-D, and the degradation product desethylatrazine. The number of pesticides and modes of action of pesticides in mixtures differed spatially and were affected by land use. Waterways draining catchments where sugar cane was a major land use had mixtures with the most pesticides.

Investigating diagnostic sequencing techniques for CADASIL diagnosis

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a cerebral small vessel disease caused by mutations in the NOTCH3 gene. Our laboratory has been undertaking genetic diagnostic testing for CADASIL since 1997. Work originally utilised Sanger sequencing methods targeting specific NOTCH3 exons. More recently, next-generation sequencing (NGS)-based technologies such as a targeted gene panel and whole exome sequencing (WES) have been used for improved genetic diagnostic testing. In this study, data from 680 patient samples was analysed for 764 tests utilising 3 different sequencing technologies. Sanger sequencing was performed for 407 tests, a targeted NGS gene panel which includes NOTCH3 exonic regions accounted for 354 tests, and WES with targeted analysis was performed for 3 tests. In total, 14.7% of patient samples (n = 100/680) were determined to have a mutation. Testing efficacy varied by method, with 10.8% (n = 44/407) of tests using Sanger sequencing able to identify mutations, with 15.8% (n = 56/354) of tests performed using the NGS custom panel successfully identifying mutations and a likely non-NOTCH3 pathogenic variant (n = 1/3) identified through WES. Further analysis was then performed through stratification of the number of mutations detected at our facility based on the number of exons, level of pathogenicity and the classification of mutations as known or novel. A systematic review of NOTCH3 mutation testing data from 1997 to 2017 determined the diagnostic rate of pathogenic findings and found the NGS-customised panel increases our ability to identify disease-causing mutations in NOTCH3.

Clinical and genetic spectrum of SCN2A-associated episodic ataxia

BACKGROUND

Pathogenic variants in SCN2A are associated with various neurological disorders including epilepsy, autism spectrum disorder and intellectual disability. Few reports have recently described SCN2A-associated episodic ataxia (EA). Our study identifies its broader clinical and genetic spectrum, and describes pharmacological approaches.

RESULTS

We report 21 patients with SCN2A-associated EA, of which 9 are unpublished cases. The large majority of patients present with epileptic seizures (18/21, 86%), often starting within the first three months of life (12/18, 67%). In contrast, onset of episodic ataxia ranged from 10 months to 14 years of age. The frequency of EA episodes ranged from brief, daily events up to 1-2 episodes per year each lasting several weeks. Potential triggers include minor head traumas and sleep deprivation. Cognitive outcome is favorable in most patients with normal or mildly impaired cognitive development in 17/21 patients (81%). No clear genotype-phenotype correlations were identified in this cohort. However, two mutational hotspots were identified, i.e. 7/21 patients (33%) harbor the identical pathogenic variant p.A263V, whereas 5/21 (24%) carry pathogenic variants that affect the S4 segment and its cytoplasmic loop within the domain IV. In addition, we identified six novel pathogenic variants in SCN2A. While acetazolamide was previously reported as beneficial in SCN2A-associated EA in one case, our data show a conflicting response in 8 additional patients treated with acetazolamide: three of them profited from acetazolamide treatment, while 5/8 did not.

CONCLUSIONS

Our study describes the heterogeneous clinical spectrum of SCN2A-associated EA, identifies two mutational hotspots and shows positive effects of acetazolamide in about 50%.

Observation of a superconducting glass state in granular superconducting diamond

The magnetic field dependence of the superconductivity in nanocrystalline boron doped diamond thin films is reported. Evidence of a superconducting glass state is presented, as demonstrated by the observation of a quasi de Almeida-Thouless line in the phase diagram and a logarithmic time dependence of the magnetism. The position of the phase boundary in the H-T plane is determined from electrical transport data by detailed fitting to quasi-zero-dimensional fluctuation conductivity theory. This allows determination of the boundary between resistive and non-resistive behaviour to be made with greater precision than the standard ad hoc onset/midpoint/offset criterion. We attribute the glassy superconductivity to the morphological granularity of the diamond films.

A pilot investigation of differential neuroendocrine associations with fronto-limbic activation during semantically-cued list learning in mood disorders

BACKGROUND

Decreased volume and disrupted function in neural structures essential for memory formation (e.g. medial temporal lobe and prefrontal cortex) are common among individuals with depression. Hypothalamic-pituitary-axis function, as reflected by measurement of cortisol levels, is linked to neural activity during memory encoding in healthy people. However, it is not as well understood whether cortisol is associated with alterations in fronto-temporal recruitment during memory encoding in depression.

METHODS

In this pilot study, we evaluated associations between cortisol and neural activation during memory encoding in 62 adults (18-65 years) with mood disorders (MD; n = 39, 66.7% female), including major depression (n = 28) and bipolar I disorder (n = 11), and healthy controls (HC; n = 23, 43.5% female). Participants provided salivary cortisol samples before and after completing a semantically-cued list-learning task during 3-Tesla fMRI. Links between pre-scan cortisol (and cortisol change) and activation during encoding were evaluated using block and event-related models.

RESULTS

Overall, pre-scan cortisol level was positively associated with greater engagement of fronto-limbic activation during the encoding block. However, in MD, pre-scan cortisol was associated with attenuated activation during encoding in medial frontal, superior and middle temporal gyri, insula, lingual gyrus, and claustrum relative to HCs. Cortisol-related attenuation of activation in MD was also observed during encoding of words subsequently recalled in the ventral anterior cingulate, hypothalamus, and middle temporal gyrus. By and large, cortisol change (pre/post scan) predicted the same pattern of findings in both block and event-related contrasts.

LIMITATIONS

Although analyses accounted for variations in scanner time of day, circadian alterations in cortisol may have introduced variability into the results.

CONCLUSIONS

Pre-scan cortisol may selectively interfere with recruitment of important fronto-temporal memory circuitry in mood disorders. The inverted associations between cortisol and neural function in MD relative to HC also elucidate potentially unique pathophysiological markers of mood disorders.

Whole body PD-L1 PET in patients with NSCLC and melanoma

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Background: PD-(L)1 immunotherapy is effective in multiple tumors, including NSCLC and melanoma, but tumor PD-L1 IHC correlates only moderately with treatment outcome. This study aims to assess 1) safety of 18F-BMS-986192 (18F-PD-L1) in human, 2) PD-L1 quantification in tumors using 18F-PD-L1 PET, 3) PD-L1 PET correlation with IHC and treatment outcome, and 4) intra and inter subject tracer uptake variability. Methods: Pts with NSCLC (N = 10) and melanoma (N = 3) were included. At baseline, pts received a static or multiphase dynamic whole body PET scan after injecting 200 MBq 18F-BMS-986192. For NSCLC pts, (1) SUV(max, peak and mean) were measured for each delineable tumor (N = 32, 1-7 tumors/pt), (2) PD-L1 IHC (28.8 assay) was performed on the biopsy, and (3) response to Nivolumab therapy assessed by RECIST 1.1. Intra and inter subject variability and intraclass correlation were calculated using SUVs of all assessed tumors. Equal variance for PD-L1 status was evaluated by a Levene’s test. Four (3 female) pts underwent dosimetry study (ICRP 60). Results: No AEs related to radiotracer was observed. Dosimetry study demonstrated whole body exposure of 30 mGy at dose > 1400 MBq. Biodistribution among pts is comparable. PD-L1 IHC from 13 biopsied lesions were evaluated, 5 < 1%, 4 ≥1%, and 4 ≥50%. Tumor tracer uptake was measured in NSCLC pts and categorized by PDL-1 IHC as ≥50% or < 50%. Clinical trial information: 2015-004760-11. Tumor SUVs did not correlate with RECIST 1.1 assessment. Lesion heterogeneity was reflected in both inter and intra pt variability (CVinter = 41%, CVintra = 53%, ICC = 0.41 for SUVpeak). Levene’s test showed no significance in variability between the two PD-L1 categories. Conclusions: PET-imaging with 18F-BMS-986192 is safe and feasible in pts with NSCLC and melanoma. Pts with higher PD-L1 PET SUV have higher PD-L1 by IHC. Intra pt variability is similar to inter pt variability. With limited number of pts, no clear correlation of PET PD-L1 and tumor response is observed. A prospective study with this tracer is underway to further investigate 18F-BMS-986192 in understanding of PD-L1 expression.[Table: see text]

Staged reconstruction of diaphyseal fractures with segmental defects: Surgical and patient-reported outcomes

INTRODUCTION

Two-stage limb reconstruction is an option for patients with critical size segmental bone defects following acute trauma or non-union. Reconstruction is technically demanding and associated with a high complication rate. Current protocols for limb reconstruction have well-documented challenges, and no study has reported on patient outcomes using a validated questionnaire. In this study, we aimed to examine the clinical and patient-centered outcomes following our surgical protocol for two-stage limb reconstruction following critical size segmental defects.

PATIENTS AND METHODS

A single surgeon performed reconstruction of long bone defects using antibiotic impregnated cement spacers and intramedullary cancellous bone autograft. A retrospective chart review was performed. Three reviewers independently measured time to union based on radiographs. The Lower Extremity Functional Scale (LEFS) survey was administered to patients after most recent follow-up.

RESULTS

Ten limbs representing nine patients were included. All patients sustained a lower extremity injury, and one patient had bilateral lower extremity injuries. Average clinical follow-up was 18.3 months (range 7-33) from final surgical intervention, and follow-up to questionnaire administration was 28 months (range 24-37). The mean time between stages was 3.1 months. Average time to unrestricted weight-bearing was 7.9 months from Stage 1 (range 3.4-15.9) and 4.5 months from Stage 2 (range 1.1-11.6). Average time to full union was 16.7 months from Stage 1 (range 6.4-28.6) and 13.5 months from Stage 2 (range 1.8-27). Eight patients (nine limbs) participated in the LEFS survey, the average score was 53.1 (range 30-67), equating to 66% of full functionality (range 38%-84%). Complications included 5 infections, 3 non-unions, and one amputation. There was a moderate positive correlation between infection at any time point and non-union (R=0.65, p=0.03).

DISCUSSION AND CONCLUSIONS

Outcomes in this small patient cohort were good despite risks of complication. There is an association between infection and non-union. Further studies addressing clinical and functional outcomes will help to guide expectations for future surgeons and patients.

A modular route to boron doped PAHs by combining borylative cyclisation and electrophilic C-H borylation

Starting from simple alkynes, sequential borylative cyclisation/electrophilic C–H borylation represents a simple modular route to novel B-doped PAHs.

Heteroatom doping into polyaromatic hydrocarbons (PAHs) is a powerful approach for modifying key physical properties, however, there are extremely few modular routes that enable facile formation of B-, B₂- and B,N-(specifically not containing direct B–N bonds) doped PAHs despite the growing importance of these materials. Sequential, one pot borylative cyclisation/intramolecular electrophilic C–H borylation of naphthyl-alkynes provides a simple new route to access novel B-, B,N- and B₂-doped (PAHs). The initial products, dihydronaphthalene/dihydroquinoline B-mesityl PAHs, were reacted with [Ph₃C][BF₄]/pyridyl base to form the oxidised B-, and B,N-doped PAHs. However, for B-triisopropylphenyl (Trip) PAH congeners oxidation has to be performed prior to Trip installation due to preferential oxidation of an isopropylaryl moiety to the styrene. This alternative sequence enables access to Trip-B-PAHs and to structurally constrained B and B₂-PAHs. Analysis of the solid state structures and optoelectronic properties of these PAHs confirm that frontier orbital energies, extended packing structures, Stokes shift and quantum yields all can be rationally modified using this methodology. The simplicity of this synthetic approach makes it a powerful tool for rapidly generating novel bench stable boron doped PAHs, which is important for facilitating further structure–property relationship studies and the wider utilisation of these materials in optoelectronic applications.

Absolute calibration of optical streak cameras on picosecond time scales using supercontinuum generation

We report a new method using high-stability, laser-driven supercontinuum generation in a liquid cell to calibrate the absolute photon response of fast optical streak cameras as a function of wavelength when operating at fastest sweep speeds. A stable, pulsed white light source based around the use of self-phase modulation in a salt solution was developed to provide the required brightness on picosecond time scales, enabling streak camera calibration in fully dynamic operation. The measured spectral brightness allowed for absolute photon response calibration over a broad spectral range (425-650 nm). Calibrations performed with two Axis Photonique streak cameras using the Photonis P820PSU streak tube demonstrated responses that qualitatively follow the photocathode response. Peak sensitivities were one photon/count above background. The absolute dynamic sensitivity is less than the static by up to an order of magnitude. We attribute this to the dynamic response of the phosphor being lower.

Monte Carlo profile confidence intervals for dynamic systems

Monte Carlo methods to evaluate and maximize the likelihood function enable the construction of confidence intervals and hypothesis tests, facilitating scientific investigation using models for which the likelihood function is intractable. When Monte Carlo error can be made small, by sufficiently exhaustive computation, then the standard theory and practice of likelihood-based inference applies. As datasets become larger, and models more complex, situations arise where no reasonable amount of computation can render Monte Carlo error negligible. We develop profile likelihood methodology to provide frequentist inferences that take into account Monte Carlo uncertainty. We investigate the role of this methodology in facilitating inference for computationally challenging dynamic latent variable models. We present examples arising in the study of infectious disease transmission, demonstrating our methodology for inference on nonlinear dynamic models using genetic sequence data and panel time-series data. We also discuss applicability to nonlinear time-series and spatio-temporal data.

Whole body PD-1 and PD-L1 PET with 89Zr-nivolumab and 18F- BMS-986192 in pts with NSCLC

e20047

Background: Tumor PD-L1 IHC relates moderately with treatment outcome following anti-PD-(L)1 monotherapy in pts with NSCLC. Aim: 1. To assess safety of the PET procedures. 2. To quantify PD-1 and PD-L1 expression in tumors with 89Zirconium-labeled nivolumab (89Zr-nivo) and 18F-labeled BMS-986192 (18F-PD-L1) PET. 3. To assess intra- and inter-patient tracer uptake differences in tumors. 4. To correlate PET results with IHC and treatment outcome. Methods: NSCLC pts eligible for treatment with nivolumab were included. Pts received a dynamic and static whole body 18F-PD-L1 and a static 89Zr-nivo PET scan. A baseline tumor biopsy was required and up to two additional biopsies were allowed in case PET showed heterogeneous tumor uptake. SUVpeak was calculated for all delineable tumor lesions and related to PD-(L)1 IHC (28.8 assay) and response after 6 wks of nivolumab treatment. Results: 7 pts (5 ≥1%, 2 ≥50% and 2 negative by PD-L1 IHC) were enrolled and 11 lesions analyzed. No toxicity related to radiotracer administration was identified. Tumor uptake of both tracers was visualized in all pts. There was substantial variability among pts for 18F-PD-L1 (mean SUV 5.4, range 2.2 - 14.4) and 89Zr-nivo (mean SUV 5.0, range 1.6 - 9.7). Intra-patient tracer uptake heterogeneity was also seen: mean 2.5-fold (±0.96) and 2.3-fold (±0.86) differences between lesions for 18F-PD-L1 and 89Zr-nivo SUV, respectively. For lesions with < 50% PD-L1 IHC mean 18F-PD-L1 SUV was 3.4 (±2.9) as compared to 7.1 (±6.0) for lesions with ≥50% PD-L1 IHC (p = 0.22). For lesions with low PD-1 expression mean 89Zr-nivo SUV was 6.9 (±2.7) as compared to 8.1 (±2.0) for lesions with high PD-1 expression (p = 0.44). Five pts were evaluable for response evaluation: 1 PR, 2 SD and 2 PD with 18F-PD-L1 SUV values (most PET avid lesion) of 14.4 (PR), 2.0 and 5.4 (SD) and 6.4 and 6.6 (PD). Conclusion: 1.PET-imaging with both tracers is safe and feasible, with good tumor-to-normal tissue contrast. 2. Tumor uptake demonstrated substantial heterogeneity among pts and among tumors within the same pts. 3. Although higher 18F-PD-L1 tumor uptake was seen in pts with ≥50% tumor PD-L1 IHC and the highest 18F-PD-L1 SUV was measured in the responding pt, the dataset is still very small. Clinical trial information: 2015-004760-11.

Low-noise time-resolved optical sensing of electromagnetic pulses from petawatt laser-matter interactions

We report on the development and deployment of an optical diagnostic for single-shot measurement of the electric-field components of electromagnetic pulses from high-intensity laser-matter interactions in a high-noise environment. The electro-optic Pockels effect in KDP crystals was used to measure transient electric fields using a geometry easily modifiable for magnetic field detection via Faraday rotation. Using dielectric sensors and an optical fibre-based readout ensures minimal field perturbations compared to conductive probes and greatly limits unwanted electrical pickup between probe and recording system. The device was tested at the Vulcan Petawatt facility with 1020 W cm-2 peak intensities, the first time such a diagnostic has been used in this regime. The probe crystals were located ~1.25 m from target and did not require direct view of the source plasma. The measured signals compare favourably with previously reported studies from Vulcan, in terms of the maximum measured intra-crystal field of 10.9 kV/m, signal duration and detected frequency content which was found to match the interaction chamber's horizontal-plane fundamental harmonics of 76 and 101 MHz. Methods for improving the diagnostic for future use are also discussed in detail. Orthogonal optical probes offer a low-noise alternative for direct simultaneous measurement of each vector field component.

Anomalous Heating and Plasmoid Formation in a Driven Magnetic Reconnection Experiment

We present a detailed study of magnetic reconnection in a quasi-two-dimensional pulsed-power driven laboratory experiment. Oppositely directed magnetic fields (B=3  T), advected by supersonic, sub-Alfvénic carbon plasma flows (V_{in}=50  km/s), are brought together and mutually annihilate inside a thin current layer (δ=0.6  mm). Temporally and spatially resolved optical diagnostics, including interferometry, Faraday rotation imaging, and Thomson scattering, allow us to determine the structure and dynamics of this layer, the nature of the inflows and outflows, and the detailed energy partition during the reconnection process. We measure high electron and ion temperatures (T_{e}=100  eV, T_{i}=600  eV), far in excess of what can be attributed to classical (Spitzer) resistive and viscous dissipation. We observe the repeated formation and ejection of plasmoids, consistent with the predictions from semicollisional plasmoid theory.

Generation of high contrast and high spatial quality idler from a low-gain optical parametric amplifier

The temporal contrast of a regeneratively amplified, sub-picosecond pulse is enhanced by employing a low-gain optical parametric amplification stage self-pumped by the second harmonic of the pulse. Through careful characterization of the two related nonlinear processes and optimization of the non-collinear geometry, a robust high-contrast idler pulse has been generated, with excellent spatial quality in both the near and far field. The overall energy conversion efficiency exceeds 14%, with 33% intensity conversion efficiency. The temporal cleaning is implemented without any bandwidth losses or spectral shift and produces approximately 20% temporal shortening. These experimental findings are in excellent agreement with numerical calculations.

Supine sleep positioning in preterm and term infants after hospital discharge from 2000 to 2011

OBJECTIVE

Supine sleep positioning (SSP) has been shown to reduce the risk of sudden infant death syndrome (SIDS) and preterm infants are at higher risk for SIDS. Population-based estimates of SSP are lacking for the preterm population. The objectives of this study are: (1) compare the prevalence of SSP after hospital discharge for preterm and term infants in the United States; and (2) assess racial/ethnic disparities in SSP for preterm and term infants.

STUDY DESIGN

We analyzed the 2000 to 2011 data from the Pregnancy Risk Assessment Monitoring System of Centers for Disease Control and Prevention from 35 states. We measured prevalence of SSP by preterm and term gestational age (GA) categories. We calculated adjusted prevalence ratios (APR) to evaluate the likelihood of SSP for each GA category compared with term infants and the likelihood of SSP for non-Hispanic black (NHB) and Hispanic infants compared with non-Hispanic white (NHW) infants.

RESULTS

Prevalence of SSP varied by GA: ⩽27, 59.7%; 28 0/7 to 33 6/7, 63.7%; 34 0/7 to 36 6/7 (late preterm), 63.6%; and 37 0/7 to 42 6/7 (term) weeks, 66.8% (P<0.001). In the adjusted analyses, late preterm infants were slightly less likely to be placed in SSP compared with term infants (APR: 0.96, confidence interval: 0.95 to 0.98). There were racial/ethnic disparities in SSP for all GA categories when NHB and Hispanic infants were compared with NHW infants.

CONCLUSIONS

All infants had suboptimal adherence to SSP indicating a continued need to better engage families about SSP. Parents of late preterm infants and families of NHB and Hispanic infants will also require greater attention given their decreased likelihood of SSP.

Assessment of Titanium Alloy on Polyethylene Bearing Surfaces in Retrieved Uncemented Total Hip Replacements

Changes to the bearing surfaces of eighteen uncemented total hip replacements retrieved at revision surgery were assessed by three-dimensional binocular microscopy, Rank Taylor Hobson talysurf measurements, scanning electron microscopy, and X-ray dispersive analysis. Abrasions on the non-articular surface of the polyethylene cups were present. Bone particles were found in tracks in the bearing surfaces of both the titanium femoral heads and the polyethylene cups and were responsible for wear of these surfaces. Although the wear of the femoral heads appeared substantial to naked eye examination, the surface finish of these surfaces remained within the British ISO standards for titanium alloy when assessed by the methods used above. This study concluded that direct contact between polyethylene and bone should be avoided in total hip arthroplasty and that ‘third body’ wear from bone particles occurred in these uncemented prostheses. Both components of this type of implant should be replaced at revision surgery and titanium should be avoided as a bearing surface in hip arthroplasty. Present methods of assessing the surface finish of titanium should be re-evaluated and more reliable ones considered.

Number needed to screen: lives saved over 20 years of follow-up in mammographic screening

Objective: To estimate the number needed to screen with mammography to save one life, based on a stated amount of screening activity and long-term follow-up for breast cancer death.

Setting: A randomised controlled trial of mammographic screening for breast cancer, with 77,080 women invited to screening and 55,985 not invited. The invited group was offered screening for seven years. Follow-up continued for a total of just over 20 years.

Methods: Number needed to screen for seven years to save one life over 20 years was calculated by dividing the number screened (not the number invited) by the total number of lives saved. Similarly, we calculated the number of mammographic examinations required to save one life.

Results: We estimate that the number of women needed to screen for seven years to save one life over 20 years is 465 (95% CI 324–819). The number of mammographic examinations needed to save one life was 1499 (95% CI 1046–2642).

Conclusions: The number needed to screen to save one life is smaller than has been reported in the past. Mammographic screening is effective in absolute terms as well as relative. Long-term follow-up allowed us to estimate the absolute benefit with greater accuracy.

Structure of a Magnetic Flux Annihilation Layer Formed by the Collision of Supersonic, Magnetized Plasma Flows

We present experiments characterizing the detailed structure of a current layer, generated by the collision of two counterstreaming, supersonic and magnetized aluminum plasma flows. The antiparallel magnetic fields advected by the flows are found to be mutually annihilated inside the layer, giving rise to a bifurcated current structure-two narrow current sheets running along the outside surfaces of the layer. Measurements with Thomson scattering show a fast outflow of plasma along the layer and a high ion temperature (T_{i}∼Z[over ¯]T_{e}, with average ionization Z[over ¯]=7). Analysis of the spatially resolved plasma parameters indicates that the advection and subsequent annihilation of the inflowing magnetic flux determines the structure of the layer, while the ion heating could be due to the development of kinetic, current-driven instabilities.

Complement-here, there and everywhere, but what about the transplanted organ?

The part of the innate immune system that communicates and effectively primes the adaptive immune system was termed "complement" by Ehrlich to reflect its complementarity to antibodies having previously been described as "alexine" (i.e protective component of serum) by Buchner and Bordet. It has been established that complement is not solely produced systemically but may have origin in different tissues where it can influence organ specific functions that may affect the outcome of transplanted organs. This review looks at the role of complement in particular to kidney transplantation. We look at current literature to determine whether blockade of the peripheral or central compartments of complement production may prevent ischaemic reperfusion injury or rejection in the transplanted organ. We also review new therapeutics that have been developed to inhibit components of the complement cascade with varying degrees of success leading to an increase in our understanding of the multiple triggers of this complex system. In addition, we consider whether biomarkers in this field are effective markers of disease or treatment.

Detection and characterization of viruses as field and vaccine strains in feedlot cattle with bovine respiratory disease

This study investigated viruses in bovine respiratory disease (BRD) cases in feedlots, including bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine coronaviruses (BoCV) and parainfluenza-3 virus (PI3V). Nasal swabs were collected from 114 cattle on initial BRD treatment. Processing included modified live virus (MLV) vaccination. Seven BRD necropsy cases were included for 121 total cases. Mean number of days on feed before first sample was 14.9 days. Swabs and tissue homogenates were tested by gel based PCR (G-PCR), quantitative-PCR (qPCR) and quantitative real time reverse transcriptase PCR (qRT-PCR) and viral culture. There were 87/114 (76.3%) swabs positive for at least one virus by at least one test. All necropsy cases were positive for at least one virus. Of 121 cases, positives included 18/121 (14.9%) BoHV-1; 19/121 (15.7%) BVDV; 76/121 (62.8%) BoCV; 11/121 (9.1%) BRSV; and 10/121 (8.3%) PI3V. For nasal swabs, G-PCR (5 viruses) detected 44/114 (38.6%); q-PCR and qRT-PCR (4 viruses) detected 81/114 (71.6%); and virus isolation detected 40/114 (35.1%). Most were positive for only one or two tests, but not all three tests. Necropsy cases had positives: 5/7 G-PCR, 5/7 q-PCR and qRT-PCR, and all were positive by cell culture. In some cases, G-PCR and both real time PCR were negative for BoHV-1, BVDV, and PI3V in samples positive by culture. PCR did not differentiate field from vaccines strains of BoHV-1, BVDV, and PI3V. However based on sequencing and analysis, field and vaccine strains of culture positive BoHV-1, BoCV, BVDV, and PI3V, 11/18 (61.1%) of BoHV-1 isolates, 6/17 (35.3%) BVDV isolates, and 1/10 (10.0%) PI3V identified as vaccine. BRSV was only identified by PCR testing. Interpretation of laboratory tests is appropriate as molecular based tests and virus isolation cannot separate field from vaccine strains. Additional testing using sequencing appears appropriate for identifying vaccine strains.

Multiwavelength interferometry system for the Orion laser facility

We report on the design and testing of a multiwavelength interferometry system for the Orion laser facility based upon the use of self-path matching Wollaston prisms. The use of UV corrected achromatic optics allows for both easy alignment with an eye-safe light source and small (∼ millimeter) offsets to the focal lengths between different operational wavelengths. Interferograms are demonstrated at wavelengths corresponding to first, second, and fourth harmonics of a 1054 nm Nd:glass probe beam. Example data confirms the broadband achromatic capability of the imaging system with operation from the UV (263 nm) to visible (527 nm) and demonstrates that features as small as 5 μm can be resolved for object sizes of 15 by 10 mm. Results are also shown for an off-harmonic wavelength that will underpin a future capability. The primary optics package is accommodated inside the footprint of a ten-inch manipulator to allow the system to be deployed from a multitude of viewing angles inside the 4 m diameter Orion target chamber.

An in-vacuo optical levitation trap for high-intensity laser interaction experiments with isolated microtargets

We report on the design, construction, and characterisation of a new class of in-vacuo optical levitation trap optimised for use in high-intensity, high-energy laser interaction experiments. The system uses a focused, vertically propagating continuous wave laser beam to capture and manipulate micro-targets by photon momentum transfer at much longer working distances than commonly used by optical tweezer systems. A high speed (10 kHz) optical imaging and signal acquisition system was implemented for tracking the levitated droplets position and dynamic behaviour under atmospheric and vacuum conditions, with ±5 μm spatial resolution. Optical trapping of 10 ± 4 μm oil droplets in vacuum was demonstrated, over timescales of >1 h at extended distances of ∼40 mm from the final focusing optic. The stability of the levitated droplet was such that it would stay in alignment with a ∼7 μm irradiating beam focal spot for up to 5 min without the need for re-adjustment. The performance of the trap was assessed in a series of high-intensity (10(17) W cm(-2)) laser experiments that measured the X-ray source size and inferred free-electron temperature of a single isolated droplet target, along with a measurement of the emitted radio-frequency pulse. These initial tests demonstrated the use of optically levitated microdroplets as a robust target platform for further high-intensity laser interaction and point source studies.

Hallucinations and illusions in migraine in children and the Alice in Wonderland Syndrome

DESIGN

A prospective observational study over 1 year.

SETTING

A District General Hospital, and Child and Adolescent Mental Health Department.

PATIENTS

Children aged 8-18 years living in the catchment area of a district hospital service with any type of unexplained hallucinations or illusions associated with or without an established diagnosis of migraine.

RESULTS

The study identified nine children with a combination of migraine and a variety of hallucinations and illusions, including illusions of size, time, colour, body shape, movement and visual and auditory hallucination. An average of 10 symptoms (range 7-15) were reported.

INTERVENTIONS

None.

MAIN OUTCOME MEASURE

None.

CONCLUSIONS

It is important to recognise these symptoms to enable appropriate history taking and diagnosis. These symptoms are common and currently seem to go unrecognised and may pose diagnostic difficulties if onset is before typical migraine headaches occur.

Monochromatic radiography of high energy density physics experiments on the MAGPIE generator

A monochromatic X-ray backlighter based on Bragg reflection from a spherically bent quartz crystal has been developed for the MAGPIE pulsed power generator at Imperial College (1.4 MA, 240 ns) [I. H. Mitchell et al., Rev. Sci. Instrum. 67, 1533 (2005)]. This instrument has been used to diagnose high energy density physics experiments with 1.865 keV radiation (Silicon He-α) from a laser plasma source driven by a ∼7 J, 1 ns pulse from the Cerberus laser. The design of the diagnostic, its characterisation and performance, and initial results in which the instrument was used to radiograph a shock physics experiment on MAGPIE are discussed.

Diagnosing collisions of magnetized, high energy density plasma flows using a combination of collective Thomson scattering, Faraday rotation, and interferometry (invited)

A suite of laser based diagnostics is used to study interactions of magnetised, supersonic, radiatively cooled plasma flows produced using the Magpie pulse power generator (1.4 MA, 240 ns rise time). Collective optical Thomson scattering measures the time-resolved local flow velocity and temperature across 7-14 spatial positions. The scattering spectrum is recorded from multiple directions, allowing more accurate reconstruction of the flow velocity vectors. The areal electron density is measured using 2D interferometry; optimisation and analysis are discussed. The Faraday rotation diagnostic, operating at 1053 nm, measures the magnetic field distribution in the plasma. Measurements obtained simultaneously by these diagnostics are used to constrain analysis, increasing the accuracy of interpretation.

Interpenetration, deflection, and stagnation of cylindrically convergent magnetized supersonic tungsten plasma flows

The interpenetration and interaction of supersonic, magnetized tungsten plasma flows has been directly observed via spatially and temporally resolved measurements of the Thomson scattering ion feature. A novel scattering geometry allows independent measurements of the axial and radial velocity components of the ions. The plasma flows are produced via the pulsed power driven ablation of fine tungsten wires in a cylindrical wire array z pinch. Fits of the data reveal the variations in radial velocity, axial velocity, and temperature of the ion streams as they interpenetrate and interact. A previously unobserved increase in axial velocity is measured near the array axis. This may be the result of v[over →]×B[over →] bending of the ion streams by a toroidal magnetic field, advected to and accumulated about the axis by the streams.

Abstract P4-03-07: The contribution of mammographic appearance, basal-like phenotype, and disease extent to prediction of breast cancer death

Background: Advances in molecular medicine and subtyping breast cancer, in addition to conventional treatment indicators, are playing an increasing role in predicting prognosis and tailoring breast cancer treatment. To date, the emphasis principally has been to ensure that treatment is sufficiently aggressive, but in an era when women are increasingly being diagnosed with localized, favorable prognosis cancers, equal emphasis is needed to avoid overtreatment.

Objectives: We differentiated the risk of breast cancer death in a longitudinal cohort of women diagnosed with breast cancer, using three parameters of breast tumor extent and biology, specifically basal-like phenotype, histologic tumor distribution (unifocal, multifocal, diffuse), and mammographic appearance of the tumor, allowing for conventional tumor attributes and treatment modalities.

Methods: Using a prospective cohort study design, 498 consecutive patients who had been diagnosed with invasive breast cancer at Falun Central Hospital between 1996 and 1998 were enrolled as the test cohort. We assessed the independent effects of the three parameters on the 14-year risk of breast cancer death by estimating the relative contribution of each predictor in proportional hazards regression. Based on these results, we classified prognosis into four categories. External validation was then performed using independent data from a validation cohort of 848 consecutive patients diagnosed with invasive breast cancer in the same institution between 2006 and 2008.

Results: Mammographic appearance of the tumor was an independent predictor of risk of breast cancer death (P = 0.0003); the presence of casting type calcifications and architectural distortion on the mammogram were associated with 3.13-fold (95% CI: 1.46-6.70) and 3.19-fold (95% CI: 1.55-6.56) risks of breast cancer death, respectively. The basal-like phenotype independently conferred a 2.68-fold (95% CI: 1.33-5.39) risk of breast cancer death compared with the non-basal type. The association between histologic tumor distribution and risk of breast cancer death was marginally statistically significant (P = 0.0741). The observed deaths did not differ significantly from expected in the validation cohort, indicating adequacy of model prediction.

Conclusions: Combining the three parameters, i.e., basal-like phenotype, histologic tumor distribution (unifocal, multifocal, diffuse), and mammographic tumor features accurately predicted long-term risk of breast cancer death. Compared with current treatment planning protocols, risk classification based on basal-like phenotype, histologic tumor distribution (unifocal, multifocal, diffuse), and mammographic appearance, allowing for conventional tumor attributes and treatment modalities, has the potential to reduce overtreatment and is worthy of further validation.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P4-03-07.

Abstract S1-10: Disparities in the estimates of benefits and harms from mammography: Are the numbers really different?

It is generally accepted that screening with mammography prevents deaths from breast cancer, although debate continues about the absolute size of the mortality benefit, and the concomitant risks associated with screening. A number of recent observational studies have claimed to find low rates of benefit in terms of reducing mortality rates or late stage disease, and high rates of overdiagnosis, defined as the diagnosis by screening of cancer which would not have been diagnosed in the patient's lifetime if screening had not taken place. These publications have achieved a high profile in the mass media and stimulated further debate. We review the apparent disparities between different reviews of the effects of mammography screening on mortality from breast cancer and on overdiagnosis. The four major reviews are the UK Independent Review, the Nordic Cochrane review, the US Preventive Services Task Force (USPSTF) review, and the EUROSCREEN review. The estimated number needed to screen/invite to prevent one death from breast cancer ranges from 111 to 2000, almost a 20-fold range. The estimated number required varies by age group, whether the intervention described is actual screening or invitation to screening, follow-up time and other factors. To assess whether these represent genuine disagreements or whether the differences are mainly due to such factors as follow-up time and target population, we converted all four to pertain to the same scenario as used in the UK Independent Review, that is to the effect of screening for 20 years from age 50 to 69 on breast cancer mortality in ages 55-79, in a UK population. When all four reviews are converted to the UK review scenario, the range of absolute benefits is now only 2.5-fold rather than 20-fold. Thus, the differences between the reviews with respect to the absolute breast cancer mortality reduction are almost entirely due to expressing the same basic result relative to different denominators, choice of population mortality rates, etc. Thus, the so-called controversy over the benefit of mammography screening as estimated from the trials is largely contrived. When expressed relative to the same denominator, with the same screening and follow-up periods, and using the same absolute mortality rates, absolute benefit estimates are all of the same order of magnitude, and all indicate a substantial reduction in breast cancer mortality with screening. While there are genuine disagreements about overdiagnosis, methods which adjust for lead time and underlying incidence trends yield estimates which are modest and are outweighed by the mortality benefit.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S1-10.

Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes

The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

Optical Thomson scattering measurements of plasma parameters in the ablation stage of wire array Z pinches

A Thomson scattering diagnostic has been used to measure the parameters of cylindrical wire array Z pinch plasmas during the ablation phase. The scattering operates in the collective regime (α>1) allowing spatially localized measurements of the ion or electron plasma temperatures and of the plasma bulk velocity. The ablation flow is found to accelerate towards the axis reaching peak velocities of 1.2-1.3×10(7) cm/s in aluminium and ∼1×10(7) cm/s in tungsten arrays. Precursor ion temperature measurements made shortly after formation are found to correspond to the kinetic energy of the converging ablation flow.

S4-1: Overdiagnosis in Breast Cancer Screening: Methodological Considerations of Current Estimates

Background

A harm that has received considerable attention in breast cancer screening is overdiagnosis, i.e., the detection through screening of breast cancer that is non-progressive. Since there is no way to distinguish a truly non-progressive tumor from one that is progressive, overdiagnosis is a statistical phenomenon that is estimated as the difference between observed and expected incidence rates. However, there is no agreement on the true rate of overdiagnosis in breast cancer screening. Estimates vary widely, with the highest estimates reported in the scientific literature having received significant media attention under the premise that a signifiant fraction of newly diagnosed breast cancers are non-progressive and thus overtreated. We examined the range of overdiagnosis estimates in the context of factors that influence observed and expected breast cancer incidence rates over time.

Methods

Only studies that compared incidence rates of invasive breast cancer, or invasive breast cancer and ductal carcinoma in situ (DCIS), in a group invited or exposed to mammography compared with a group not invited or not exposed to mammography were included in our analysis. Studies were evaluated based on whether or not they adjusted for contemporaneous trends in the underlying incidence of disease, which may differ in different age groups, and age-specific effect on incidence rates due to lead time.

Results

We identified 17 studies (Table 1) that attempted to estimate overdiagnosis of breast cancer resulting from mammography screening. The main determinant of high estimated rates of overdiagnosis was a failure to adjust for lead time. The highest rate of overdiagnosis (33%) occurred in the one study that did not correct for either lead time or confounders. Studies that only partially corrected for lead time and confounding also had high estimates of overdiagnosis (mean = 30%), whereas studies that corrected for both lead time and confounders had the lowest estimate of overdiagnosis (mean =5%).

Conclusion

The possibility that some breast cancers detected by mammography are indolent and not life threatening within the patient's natural life is real. However, it is clear from our analysis that the wide range of estimates of overdiagnosis are due to whether or not studies have adjusted for factors in and outside of screening programs known to influence incidence rates over time. Our findings suggest that the true rate of overdiagnosis associated with breast cancer screening, to the extent that it exits at all, is small.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr S4-1.

Semaphorin-plexin signalling genes associated with human breast tumourigenesis

INTRODUCTION

Gene expression profiling has enabled us to demonstrate the heterogeneity of breast cancers. The potential of a tumour to grow and metastasise is partly dependant on its ability to initiate angiogenesis or growth and remodelling of new blood vessels, usually from a pre-existing vascular network, to ensure delivery of oxygen, nutrients, and growth factors to rapidly dividing transformed cells along with access to the systemic circulation. Cell-cell signalling of semaphorin ligands through interaction with their plexin receptors is important for the homeostasis and morphogenesis of many tissues and has been widely studied for a role in neural connectivity, cancer, cell migration and immune responses. This study investigated the role of four semaphorin/plexin signalling genes in human breast cancers in vivo and in vitro.

MATERIALS AND METHODS

mRNA was extracted from formalin fixed paraffin embedded archival breast invasive ductal carcinoma tissue samples of progressive grades (grades I-III) and compared to tissue from benign tumours. Gene expression profiles were determined by microarray using the Affymetrix GeneChip® Human Genome U133 Plus 2.0 Arrays and validated by Q-PCR using a Corbett RotorGene 6000. Following validation, the gene expression profile of the identified targets was correlated with those of the human breast cancer cell lines MCF-7 and MDA-MD-231.

RESULTS

The array data revealed that 888 genes were found to be significantly (p≤0.05) differentially expressed between grades I and II tumours and 563 genes between grade III and benign tumours. From these genes, we identified four genes involved in semaphorin-plexin signalling including SEMA4D which has previously been identified as being involved in increased angiogenesis in breast cancers, and three other genes, SEMA4F, PLXNA2 and PLXNA3, which in the literature were associated with tumourigenesis, but not directly in breast tumourigenesis. The microarray analysis revealed that SEMA4D was significantly (P=0.0347) down-regulated in the grade III tumours compared to benign tumours; SEMA4F, was significantly (P=0.0159) down-regulated between grades I and II tumours; PLXNA2 was significantly (P=0.036) down-regulated between grade III and benign tumours and PLXNA3 significantly (P=0.042) up-regulated between grades I and II tumours. Gene expression of SEMA4D was validated using Q-PCR, demonstrating the same expression profile in both data sets. When the sample set was increased to incorporate more cases, SEMA4D continued to follow the same expression profile, including statistical significance for the differences observed and small standard deviations. In vitro the same pattern was present where expression for SEMA4D was significantly higher in MDA-MB-231 cells when compared to MCF-7 cells. The expression of SEMA4F, PLXNA2 and PLXNA3 could not be validated using Q-PCR, however in vitro analysis of these three genes revealed that both SEMA4F and PLXNA3 followed the microarray trend in expression, although they did not reach significance. In contrast, PLXNA2 demonstrated statistical significance and was in concordance with the literature.

DISCUSSION

We, and others, have proposed SEMA4D to be a gene with a potentially protective effect in benign tumours that contributes to tumour growth and metastatic suppression. Previous data supports a role for SEMA4F as a tumour suppressor in the peripheral nervous system but our data seems to indicate that the gene is involved in tumour progression in breast cancer. Our in vitro analysis of PLXNA2 revealed that the gene has higher expression in more aggressive breast cancer cell types. Finally, our in vitro analysis on PLXNA3 also suggest that this gene may have some form of growth suppressive role in breast cancer, in addition to a similar role for the gene previously reported in ovarian cancer. From the data obtained in this study, SEMA4D may have a role in more aggressive and potentially metastatic breast tumours.

CONCLUSIONS

Semaphorins and their receptors, the plexins, have been implicated in numerous aspects of neural development, however their expression in many other epithelial tissues suggests that the semaphorin-plexin signalling system also contributes to blood vessel growth and development. These findings warrant further investigation of the role of semaphorins and plexins and their role in normal and tumour-induced angiogenesis in vivo and in vitro. This may represent a new front of attack in anti-angiogenic therapies of breast and other cancers.

Development of an eight gene expression profile implicating human breast tumours of all grade

The goal of improving systemic treatment of breast cancers is to evolve from treating every patient with non-specific cytotoxic chemotherapy/hormonal therapy, to a more individually-tailored direct treatment. Although anatomic staging and histological grade are important prognostic factors, they often fail to predict the clinical course of this disease. This study aimed to develop a gene expression profile associated with breast cancers of differing grades. We extracted mRNA from FFPE archival breast IDC tissue samples (Grades I-III), including benign tumours. Affymetrix GeneChip(®) Human Genome U133 Plus 2.0 Arrays were used to determine gene expression profiles and validated by Q-PCR. IHC was used to detect the AXIN2 protein in all tissues. From the array data, an independent group t-test revealed that 178 genes were significantly (P ≤ 0.01) differentially expressed between three grades of malignant breast tumours when compared to benign tissues. From these results, eight genes were significantly differentially expressed in more than one comparison group and are involved in processes implicated in breast cancer development and/or progression. The two most implicated candidates genes were CLD10 and ESPTI1 as their gene expression profile from the microarray analysis was replicated in Q-PCR analyses of the original tumour samples as well as in an extended population. The IHC revealed a significant association between AXIN2 protein expression and ER status. It is readily acknowledged and established that significant differences exist in gene expression between different cancer grades. Expansion of this approach may lead to an improved ability to discriminate between cancer grade and other pathological factors.

Meta-analysis of immunohistochemical prognostic markers in resected pancreatic cancer

BACKGROUND

The potential prognostic value of several commonly investigated immunohistochemical markers in resected pancreatic cancer is variably reported. The objective of this study was to conduct a systematic review of literature evaluating p53, p16, smad4, bcl-2, bax, vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) expression as prognostic factors in resected pancreatic adenocarcinoma and to conduct a subsequent meta-analysis to quantify the overall prognostic effect.

METHODS

Relevant literature was identified using Medline, EMBASE and ISI Web of Science. The primary end point was overall survival assessed on univariate analysis. Only studies analysing resected pancreatic adenocarcinoma were eligible for inclusion and the summary log(e) hazard ratio (logHR) and variance were pooled using an inverse variance approach. Evidence of heterogeneity was evaluated using the χ(2) test for heterogeneity and its impact on the meta-analysis was assessed by the I(2) statisic. Hazard ratios greater than one reflect adverse survival associated with positive immunostaining.

RESULTS

Vascular endothelial growth factor emerged as the most potentially informative prognostic marker (11 eligible studies, n=767, HR=1.51 (95% confidence interval, CI=1.18-1.92)) with no evidence of any significant publication bias (Egger's test, P=0.269). Bcl-2 (5 eligible studies, n=314, HR=0.51 (95% CI=0.38-0.68)), bax (5 studies, n=274, HR=0.63 (95% CI=0.48-0.83)) and p16 (3 studies, n=229, HR=0.63 (95% CI=0.43-0.92)) also returned significant overall survival differences, but in smaller patient series due to a lack of evaluable literature. Neither p53 (17 studies, n=925, HR=1.22 (95% CI=0.96-1.56)), smad4 (5 studies, n=540, HR=0.88 (95% CI=0.61-1.27)) nor EGFR (4 studies, n=250, HR=1.35 (95% CI=0.80-2.27)) was found to represent significant prognostic factors when analysing the pooled patient data. There was evidence of significant heterogeneity in four of the seven study groups.

CONCLUSION

These results support the case for immunohistochemical expression of VEGF representing a significant and reproducible marker of adverse prognosis in resected pancreatic cancer.

Quantitative, preclinical PET of translocator protein expression in glioma using 18F-N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline

Translocator protein (TSPO), also referred to as peripheral benzodiazepine receptor (PBR), is a crucial 18-kDa outer mitochondrial membrane protein involved in numerous cellular functions, including the regulation of cholesterol metabolism, steroidogenesis, and apoptosis. Elevated expression of TSPO in oncology correlates with disease progression and poor survival, suggesting that molecular probes capable of assaying TSPO levels may have potential as cancer imaging biomarkers. In preclinical PET studies, we characterized a high-affinity aryloxyanilide-based TSPO imaging ligand, 18F-N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline (18F-PBR06), as a candidate probe for the quantitative assessment of TSPO expression in glioma.

METHODS

Glioma-bearing rats were imaged with 18F-PBR06 in a small-animal PET system. Dynamic images were acquired simultaneously on injection of 18F-PBR06 (70-100 MBq/0.2 mL). Over the course of scanning, arterial blood was collected to derive the input function, with high-performance liquid chromatography radiometabolite analysis performed on selected samples for arterial input function correction. Compartmental modeling of the PET data was performed using the corrected arterial input function. Specific tumor cell binding of PBR06 was evaluated by radioligand displacement of 3H-PK 11195 with PBR06 in vitro and by displacement of 18F-PBR06 with excess PBR06 in vivo. Immediately after imaging, tumor tissue and adjacent healthy brain were harvested for assay of TSPO protein levels by Western blotting and immunohistochemistry.

RESULTS

18F-PBR06 was found to preferentially accumulate in tumors, with modest uptake in the contralateral brain, facilitating excellent contrast between tumor and adjacent tissue. Infusion with PBR06 (10 mg/kg) displaced 18F-PBR06 binding by approximately 75%. The accumulation of 18F-PBR06 in tumor tissues and adjacent brain agreed with the ex vivo assay of TSPO protein levels by Western blotting and quantitative immunohistochemistry.

CONCLUSION

These preclinical studies illustrate that 18F-PBR06 is a promising tracer for visualization of TSPO-expressing tumors. Importantly, the close correlation between 18F-PBR06 uptake and TSPO expression in tumors and normal tissues, coupled with the high degree of displaceable binding from both tumors and the normal brain, represents a significant improvement over other TSPO imaging ligands previously evaluated in glioma. These data suggest the potential of 18F-PBR06 to elucidate the role of TSPO in oncology, as well as its potential development as a cancer imaging biomarker.

Observation of a velocity domain cooling instability in a radiative shock

We report on experimental investigations into strong, laser-driven, radiative shocks in cluster media. Cylindrical shocks launched with several joules of deposited energy exhibit strong radiative effects including rapid deceleration, radiative preheat, and shell thinning. Using time-resolved propagation data from single-shot streaked Schlieren measurements, we have observed temporal modulations on the shock velocity, which we attribute to the thermal cooling instability, a process which is believed to occur in supernova remnants but until now has not been observed experimentally.

Bargaining babblers: vocal negotiation of cooperative behaviour in a social bird

Wherever individuals perform cooperative behaviours, each should be selected to adjust their own current contributions in relation to the likely future contributions of their collaborators. Here, we use the sentinel system of pied babblers (Turdoides bicolor) to show that individuals anticipate contributions by group mates, adjusting their own contribution in response to information about internal state broadcast by others. Specifically, we show that (i) short-term changes in state influence contributions to a cooperative behaviour, (ii) individuals communicate short-term changes in state, and (iii) individuals use information about the state of group mates to adjust their own investment in sentinel behaviour. Our results demonstrate that individual decisions about contributions to a cooperative effort can be influenced by information about the likely future contribution of others. We suggest that similar pre-emptive adjustments based on information obtained from collaborators will be a common feature of cooperative behaviour, and may play an important role in the development of complex communication in social species.

Pulse-length dependence of the anisotropy of laser-driven cluster explosions: transition to the impulsive regime for pulses approaching the few-cycle limit

We have experimentally observed anisotropic ion emission from Xe and Ar clusters under intense ultrashort (∼30  fs) laser irradiation, with up to 1.8 times more energetic ions emitted in the direction perpendicular to the laser polarization than in the parallel direction. As the pulse length was varied in the range of 8-160 fs, we found this anisotropy to first grow and then diminish. Treating electrons inside the unexpanded cluster as a harmonic oscillator qualitatively demonstrates how intracluster electric field can result in an ion emission anisotropy of this kind. Our observations give direct access to the initial charging dynamics present in the first few cycles of an intense laser field interacting with any nanoscale dielectric.

Considerations for the use of plasma cytokeratin 18 as a biomarker in pancreatic cancer

BACKGROUND

Enzyme-linked immunoassays of full-length (M65) and/or caspase-cleaved (M30) cytokeratin 18 (CK18) released from epithelial cells undergoing necrosis and/or apoptosis, respectively, may have prognostic or predictive biomarker utility in a range of solid tumour types. Characterisation of baseline levels of circulating full length and cleaved CK18 specifically in patients with pancreatic cancer.

METHODS

Plasma samples from 103 patients with pancreatic cancer stored at -80 degrees C were assayed for M65 and M30 levels. The median (inter-quartile range (IQR)) duration of plasma storage was 34 (23-57) months. Patients with metastatic disease (n=19) were found to have greater median (IQR) M65 levels (1145 (739-1698) U l(-1)) compared with the locally advanced (n=20; 748 (406-1150) U l(-1)) and resected (n=64; 612 (331-987) U l(-1)) patients (P=0.002). Elevated M65 levels were associated with poorer overall survival on univariate (P<0.001) but not multivariate (P=0.202) analysis. M65 concentrations also exhibited significant associations with concurrent serum-bilirubin levels (P<0.001) and the duration of plasma storage (P<0.001).

CONCLUSIONS

Baseline plasma CK18 levels in pancreatic cancer are affected by the presence of obstructive jaundice and prolonged plasma storage. Clinical biomarker studies utilising serial CK18 levels are warranted in pancreatic cancer, provided consideration is given to these potentially confounding factors.