Evaluation of the performance of a lateral flow device for quantitative detection of anti-SARS-CoV-2 IgG

INTRODUCTION

The AbC-19™ lateral flow immunoassay (LFIA) performance was evaluated on plasma samples from a SARS-CoV-2 vaccination cohort, WHO international standards for anti-SARS-CoV-2 IgG (human), individuals ≥2 weeks from infection of RT-PCR confirmed SARS-CoV-2 genetic variants, as well as microorganism serology.

METHODS

Pre-vaccination to three weeks post-booster samples were collected from a cohort of 111 patients (including clinically extremely vulnerable patients) from Northern Ireland. All patients received Oxford-AstraZeneca COVID-19 vaccination for the first and second dose, and Pfizer-BioNTech for the third (first booster). WHO international standards, 15 samples from 2 variants of concern (Delta and Omicron) and cross-reactivity with plasma samples from other microorganism infections were also assessed on AbC-19™.

RESULTS

All 80 (100%) participants sampled post-booster had high positive IgG responses, compared to 38/95 (40%) participants at 6 months post-first vaccination. WHO standard results correlated with information from corresponding biological data sheets, and antibodies to all genetic variants were detected by LFIA. No cross-reactivity was found with exception of one (of five) Dengue virus samples.

CONCLUSION

These findings suggest BNT162b2 booster vaccination enhanced humoral immunity to SARS-CoV-2 from pre-booster levels, and that this antibody response was detectable by the LFIA. In combination with cross-reactivity, standards and genetic variant results would suggest LFIA may be a cost-effective measure to assess SARS-CoV-2 antibody status.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Improving sleep in a population at high risk of trauma: A pilot study examining self-reported sleep, psychological symptomology and actigraphy measured night-time sleep

Introduction

Sleep disturbances (SDs), such as insomnia or regular nightmares, are associated with multiple mental health disorders, most notably PTSD, where SDs are reported in up to 92% of cases. Examining the effect of changing sleep on psychological symptomology is essential to develop the evidence base on the contribution of sleep to mental resilience.

Objectives

To examine the effect a short skills-based sleep intervention on psychological symptomology and actigraphy measured sleep.

Methods

A 4-session sleep skills training programme was used to treat active SDs in participants likely to have experienced occupation-associated trauma, namely military and first responders.

Results

Nineteen participants were included in the study. Insomnia Severity Index (ISI) measured; difficulty sleeping, difficulty staying asleep, waking too early, sleep satisfaction, sleep interference on quality of life and total ISI insomnia score improved significantly post-treatment (M = 9.44, SE = 7.35, p <0.001). No significant difference was identified post-treatment for actigraphy-measured sleep. The severity of depression (M = 5.27, SE = 1.41, p = 0.002), anxiety (M = 5.07, SE = 1.66, p = 0.008), and PTSD symptoms among participants with likely PTSD, were significantly lower following treatment (M = 29.4, SE = 4.19, p = 0.002).

Conclusions

A short sleep skills intervention based on CBT-I was effective at reducing self-report insomnia symptoms and severity of psychological symptomology but failed to improve actigraphy sleep metrics. These findings highlight a differing contribution of night-time sleep and current insomnia symptoms to the severity of self-reported psychological symptomology.

Disclosure

No significant relationships.

Recruitment of Older African Americans in Alzheimer's Disease Clinical Trials Using a Community Education Approach

Alzheimer's disease and related dementias (ADRD) is two times more prevalent among compared to non-Hispanic Whites. Despite the higher prevalence of ADRD among older African Americans, recent estimates suggest research enrollment by those who identify as African American remains limited. The purpose of the study is to 1) explore how a culturally tailored community education program impacts clinical trial interest and enrollment in ADRD research studies and to 2) identify how applicable the African American community perceived the culturally tailored curriculum. Using a community-engaged research approach, we collaborated with predominately African American serving community-based organizations to support content development and delivery of Aging with Grace (AWG), a culturally tailored ADRD educational curriculum. A total of five AWG presentations were given to 66 attendees. Most attendees (67%) expressed interest in participating in clinical trials after attending AWG. Enrollment increased within an observational study (84%) and lifestyle prevention clinical trials (52%) from 2018 to 2019. Attendees (32%) also perceived an increase in ADRD knowledge from attending AWG and 89.1% believed more African Americans should participate in research. Our work demonstrates the effectiveness of a culturally tailored community education program to enhance knowledge, clinical trial interest, and recruitment into observational studies and lifestyle ADRD clinical trials among older African Americans. Education programs developed in partnership with the community can serve as bridge to research participation for underrepresented minorities in clinical research. Future studies should assess long-term retention of knowledge and research readiness.

Abstract PS13-11: Oral paclitaxel and encequidar (oPac+E) in the treatment of metastatic breast cancer (mBC): Management of gastrointestinal adverse events (GI AE). Study KX-ORAX-001

Background: There is a need for more effective and less toxic treatments for patients with mBC. Patients may prefer oral vs IV cytotoxic therapies to avoid frequent hospital visits. In addition, oral therapies allow frequent or metronomic dosing regimens which may alter the toxicity or activity profile of agents vs infrequent IV administration. oPac+E is oral paclitaxel combination with Encequidar, a specific, minimally absorbed, oral p-glycoprotein inhibitor that facilitates the absorption of oral paclitaxel. mBC patients who received oPac+E had significantly greater confirmed tumor response and longer survival with lower rates and severity of neuropathy but increased GI AE compared to IV paclitaxel (IVPac) (Study KX-ORAX-001 presented at SABCS, 2019, Abstract # GS6-01).

Methods: Study KX-ORAX-001 was a phase III, randomized, study in women with mBC for whom treatment with IVPac was recommended. Patients were randomized 2:1 to receive oPac+E or IVPac. Patients continued treatment until discontinuation due to progressive disease or toxicity. oPac 205 mg/m2 was given once daily for 3 days weekly. E 12.9 mg was given 1 hour before each dose of oPac. IVPac 175 mg/m2 was infused over 3 hours every 3 weeks. The primary endpoint was efficacy defined as tumor response confirmed by BICR at two consecutive evaluations. Key secondary endpoints included PFS, OS. Safety was monitored throughout the study.

Results: All IVPac patients received high-dose dexamethasone and antihistamine premedication, which have significant anti-emetic activity and may have received additional anti-emetic agents as needed. The protocol did not allow any prophylaxis for GI AE for oPac+E patients nor were they to receive predose corticosteroids, nor antihistamines.

The protocol was amended after approximately 30% of patients were enrolled to allow prophylactic anti-emetic medications for patients randomized to oPac+E. Patients were also given loperamide to take at home and were instructed to initiate loperamide with the onset of diarrhea. The rates of Grade ≥2, vomiting and diarrhea for patients treated with IVPac, the patients treated with oPac+E prior to after the amendment are summarized in the table below.

Prophylactic anti-emetic therapy and early use of loperamide markedly decreased the incidence of ≥Grade 2 vomiting and diarrhea although there was a greater incidence than IVPac.

The most frequently prescribed anti-emetic agents for oPac+E treated patients were ondansetron (54%), metoclopramide (21%), domperidone (4%) and aprepitant (3%). For patients randomized to IVPac, the most frequently prescribed agents were ondanesteron (59%), granisetron (24%), palenosetron (7%) and aprepitant (2%). Oral administration of the oral NK1 inhibitor aprepitant appeared to be associated with increased incidence of oral paclitaxel systemic toxicity, potentially due to inhibition of metabolism of oPac by cytochrome P450 3A4.

Conclusions: oPac+E was associated with greater efficacy in the treatment of mBC and lower rates and severity of peripheral neuropathy, but increased GI AE compared to IVPac 175mg/m2. GI AE in oPac+E treated patients can be managed by prophylactic use of anti-emetics, primarily 5-HT3 inhibitors and early intervention with the anti-diarrhea agent loperamide. The use of the oral NK1 inhibitor aprepitant in combination with oPac+E is not recommended.(NTC02594371)

IVPacoPac+E Pre-AmendmentoPac+E Post AmendmentGrade 2Grade 3Grade 4Grade 2Grade 3Grade 4Grade 2Grade 3Grade 4Vomiting4%1%0%24%7%0%7%4%0%Diarrhea7%1%0%27%9%0%16%3%0.5%

Citation Format: H S Rugo, G Umanzor, F J Barrios, R H Vasallo, M A Chivalan, S Bejarano, J R Ramirez, L Fein, R D Kowalyszyn, D L Cutler, D Kramer, J Goldfinch, H Wang, T Moore, R MF Kwan. Oral paclitaxel and encequidar (oPac+E) in the treatment of metastatic breast cancer (mBC): Management of gastrointestinal adverse events (GI AE). Study KX-ORAX-001 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-11.

Abstract PS13-06: Lower rates of neuropathy with oral paclitaxel and encequidar (oPac+E) compared to IV paclitaxel (IVPac) in treatment of metastatic breast cancer (mBC): Study KX-ORAX-001

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting toxicity associated with IVPac. Primarily sensory, CIPN is an often irreversible condition primarily affecting the hands and feet associated with pain, numbness, tingling, and sensitivity to cold and has a significant impact on quality of life and treatment tolerance. Risk of CIPN increases with age, dose intensity, cumulative dose, and preexisting conditions including diabetes.

Methods: Study KX-ORAX-001 was a phase III, randomized, international study in women with mBC for whom treatment with IVPac was recommended. Eligible patients were randomized 2:1 to receive oPac+E or IVPac. Patients continued treatment until discontinuation due to progressive disease or toxicity. oPac 205 mg/m2 was given once daily for 3 days weekly. E 12.9 mg was given 1 hour before each dose of oPac. IVPac 175 mg/m2 was infused over 3 hours every 3 weeks. The primary endpoint was efficacy defined as tumor response confirmed by BICR at two consecutive evaluations. Key secondary endpoints included PFS, OS. Safety was monitored throughout the study.

Results: A total of 402 mBC patients were enrolled, 265 randomized to oPac+E and 137 to IVPac (ITT population). 399 patients were treated and comprise the safety population. The confirmed response rate was significantly greater in the oPac+E group vs IVPac (35% vs 23%) for the ITT population. Median overall survival was (27.7 vs 16.7 months, ITT) at the time of the analysis. Long-term follow up for final determination of PFS and OS is ongoing.Incidence of neuropathy-related TEAEs were lower in patients receiving oPac+E vs IVPac: Overall (21% vs 64%; all grades), grade ≥3 (2% vs 15%). Cumulative risk for neuropathy with IVPac was &gt;50% by week 8 and was 83% at week 88. In contrast, the cumulative risk of neuropathy with oPac+E rose slowly and plateaued at 34% at week 88. Treatment discontinuations due to neuropathy occurred only in the IVPac arm (8%). Dose reductions due to neuropathy were reported in 8% of IVPac treated patients and in 2% of oPac+E treated patients. In agreement with the lower rates of peripheral neuropathy in patients treated with oPac+E, there was lower use of medications used for the treatment of neuropathic symptoms. Use of gabapentin or pregabalin was 12% for patients receiving oPac+E vs 40% for IVPac treated patients.

Conclusions: oPac+E was associated with greater efficacy in the treatment of patients with mBC and a lower incidence of neuropathy, slower onset and lesser severity of neuropathic events compared to IVPac 175mg/m2 administered every three weeks. Fewer patients receiving oPac+E required dose reduction due to neuropathy and no patients receiving oPac+E discontinued treatment due to neuropathy. Reduction in neuropathy may improve quality of life and allow longer administration of effective therapy while maintaining dose intensity.

Citation Format: H S Rugo, G Umanzor, F J Barrios, R H Vasallo, M A Chivalan, S Bejarano, J R Ramirez, L Fein, R D Kowalyszyn, D L Cutler, D Kramer, J Goldfinch, H Wang, T Moore, R MF Kwan. Lower rates of neuropathy with oral paclitaxel and encequidar (oPac+E) compared to IV paclitaxel (IVPac) in treatment of metastatic breast cancer (mBC): Study KX-ORAX-001 [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS13-06.

Imaging digital arteries in systemic sclerosis by tomographic 3-dimensional ultrasound

Objective methods are needed to quantify digital artery disease in systemic sclerosis (SSc) for clinical trials of vascular therapies. Our primary aim was to examine feasibility of a novel tomographic three-dimensional-(3-D) ultrasound (tUS) with high-frequency ultrasound (HFUS) or ultra-high-frequency ultrasound (UHFUS) to assess the digital arteries in patients with SSc compared to healthy controls. A secondary objective was to compare the total wall volume (TWV) as a measure of intimal/medial thickness. Eighteen patients with a confirmed diagnosis of SSc were studied by tUS HFUS (17.5 MHz, n = 10) or tUS UHFUS (48 and 70 MHz, n = 8) with equal numbers of healthy controls of similar age and gender. The majority of patients had limited cutaneous SSc and were representative of a spectrum of digital vasculopathy, with over half (n = 6 HFUS and n = 5 UHFUS) having previous digital ulceration. Over half were receiving oral vasodilatory therapy. TWV was measured in both digital arteries of the middle finger bilaterally. At least, two digital arteries could be identified at 17.5 MHz in all patients and healthy controls. Whereas, at least two digital arteries could be identified in relatively fewer patients compared to healthy controls using 48 MHz (n = 6 and 10) and especially 70 MHz (n = 4 and 10) UHFUS. The median difference in TWV between patients and healthy controls was -6.49 mm³ using 17.5 MHz, 1.9 mm³ at 48 MHz, and -0.4 mm³ at 70 MHz. tUS using UHFUS is a feasible method to measure TWV of digital arteries in SSc. Transducer frequency plays an important factor in successful digital artery measurement, with 48 MHz being the optimal frequency.

Lower-Hybrid Drift Waves Driving Electron Nongyrotropic Heating and Vortical Flows in a Magnetic Reconnection Layer

We report measurements of lower-hybrid drift waves driving electron heating and vortical flows in an electron-scale reconnection layer under a guide field. Electrons accelerated by the electrostatic potential of the waves exhibit perpendicular and nongyrotropic heating. The vortical flows generate magnetic field perturbations comparable to the guide field magnitude. The measurements reveal a new regime of electron-wave interaction and how this interaction modifies the electron dynamics in the reconnection layer.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Impact and associates of digital pitting in patients with systemic sclerosis: a pilot study

Objective: Despite being a cardinal clinical sign of systemic sclerosis (SSc), digital pitting has been little studied. Our objective was to test, in a pilot study, the hypothesis that pitting is painful and associated with digital vascular disease severity.Method: Fifty patients with SSc were recruited: 25 with and 25 without digital pitting. Fingertip pain was assessed on a 0-10 scale. Thermography of both hands assessed surface temperature, allowing calculation of the distal-dorsal difference (temperature gradient) for each finger. Nailfold capillaroscopy was performed in each finger using a dermatoscope, and graded on a 0-3 scale (0 = normal; 3 = grossly abnormal).Results: In the 25 patients with digital pitting, 65 fingers in total were affected (mainly the index and middle fingers). Pain scores were higher in 'pitting' patients [median 4 (interquartile range 3-8) vs 0 (0-2), p < 0.001], and pitting patients reported that pitting impacted on activities of everyday living. Temperature gradients along the fingers did not differ significantly between patients with and without pitting (p = 0.248). Pitting patients were more likely to have 'grossly abnormal' capillaries than those without pitting, and less likely to have 'no/mild' nailfold capillary changes.Conclusions: Digital pitting is painful and impacts on hand function. Capillaroscopy findings provide further support for an association between pitting and severity of digital vascular change. Larger, more comprehensive studies are required to examine the pathophysiology of pitting and to pave the way to therapeutic intervention, ideally including preventive strategies.

In situ spacecraft observations of a structured electron diffusion region during magnetopause reconnection

The electron diffusion region (EDR) is the region where magnetic reconnection is initiated and electrons are energized. Because of experimental difficulties, the structure of the EDR is still poorly understood. A key question is whether the EDR has a homogeneous or patchy structure. Here we report Magnetospheric Multiscale (MMS) spacecraft observations providing evidence of inhomogeneous current densities and energy conversion over a few electron inertial lengths within an EDR at the terrestrial magnetopause, suggesting that the EDR can be rather structured. These inhomogenenities are revealed through multipoint measurements because the spacecraft separation is comparable to a few electron inertial lengths, allowing the entire MMS tetrahedron to be within the EDR most of the time. These observations are consistent with recent high-resolution and low-noise kinetic simulations.

Changes in disability and their relationship with skin thickening, in diffuse and limited cutaneous systemic sclerosis: a retrospective cohort study

OBJECTIVE

The burden of disability associated with systemic sclerosis (SSc) is being increasingly recognized. Our aim was to test the hypothesis that changes in functional ability over time differ between patients with limited (lcSSc) and diffuse cutaneous (dcSSc) subtypes, and that in dcSSc (but not lcSSc) these changes correlate with skin thickening.

METHOD

This was a retrospective analysis of data collected prospectively between 2005 and 2016 at a single centre. Data recorded at annual review visits included modified Rodnan skin score (mRSS) and Health Assessment Questionnaire Disability Index (HAQ-DI). Yearly rates of mRSS and HAQ-DI change were assessed by individual linear regressions, and those gradients were compared between disease groups (lcSSc/dcSSc) for each of early/late disease (less/greater than 5 years' duration).

RESULTS

The study included 402 patients (110 dcSSc, 292 lcSSc), with mean length of follow-up of 5.5 years (sd 3.5). Mean baseline HAQ-DI was 1.4 in dcSSc and 1.2 in lcSSc. In dcSSc, increased mRSS was associated with worsening disability (ρ = 0.36, p = 0.004) during early but not late disease (ρ = 0.12, p = 0.331). In lcSSc, changes in mRSS were not associated with changes in disability for early (ρ = -0.15, p = 0.173) or late disease (ρ = 0.10, p = 0.137).

CONCLUSION

These findings confirm high disability in patients with SSc. A relationship between HAQ-DI and mRSS (worsening mRSS associated with increasing disability) was found only in patients with early dcSSc, suggesting that in other patient subgroups other factors play the major role.

A feasibility study of a novel low-level light therapy for digital ulcers in systemic sclerosis

Background: Locally acting, well-tolerated treatments for systemic sclerosis (SSc) digital ulcers (DUs) are needed.

Objectives: Our primary aim was to investigate the safety, feasibility, and tolerability of a novel low-level light therapy (LTTT). A secondary aim was to tentatively assess efficacy.

Methods: A custom-built device comprising infrared (850 nm), red (660 nm), and violet (405 nm) LEDs was utilized. DUs were irradiated with 10 J/cm² twice weekly for 3 weeks, with follow-up at weeks 4 and 8. Any safety concerns were documented. Patient opinion on time to deliver, feasibility, and pain visual analogue score (VAS; 0–100, 100 most severe) was collected. Patient and clinician DU global assessment VAS were documented. DUs were evaluated by laser Doppler perfusion imaging pre- and post-irradiation.

Results: In all, 14 DUs in eight patients received a total of 46 light exposures, with no safety concerns. All patients considered LTTT ‘took just the right amount of time’ and was ‘feasible’, with a low associated mean pain VAS of 1.6 (SD: 5.2). Patient and clinician global DC VAS improved during the study (mean change: –7.1 and –5.2, respectively, both p < .001). DU perfusion significantly increased post-irradiation.

Conclusions: LTTT for DUs is safe, feasible, and well tolerated. There was an early tentative suggestion of treatment efficacy.

Electron Bulk Acceleration and Thermalization at Earth's Quasiperpendicular Bow Shock

Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

Deformation reconstruction by means of surface optimization. Part II: time-resolved electronic speckle pattern interferometry

An analysis of time-resolved electronic speckle pattern interferograms using an optimization algorithm is shown to provide full-field measurements of transient surface deformation. The arrangement uses a continuous-wave laser and high-speed camera to capture speckle images, with the recovery of the time-resolved deformation achieved by spatiotemporal processing using an optimization algorithm. It is shown that the process allows imaging of high-speed non-monotonic out-of-plane displacements with sub-micrometer amplitude. Time-resolved amplitude and phase recovery is demonstrated by analyzing the out-of-plane deformation of harmonic and transient events in a friction membranophone.

Quantifying the Effect of Non-Larmor Motion of Electrons on the Pressure Tensor

In space plasma, various effects of magnetic reconnection and turbulence cause the electron motion to significantly deviate from their Larmor orbits. Collectively these orbits affect the electron velocity distribution function and lead to the appearance of the "non-gyrotropic" elements in the pressure tensor. Quantification of this effect has important applications in space and laboratory plasma, one of which is tracing the electron diffusion region (EDR) of magnetic reconnection in space observations. Three different measures of agyrotropy of pressure tensor have previously been proposed, namely, A∅ _e , D_ng and Q. The multitude of contradictory measures has caused confusion within the community. We revisit the problem by considering the basic properties an agyrotropy measure should have. We show that A∅ _e , D_ng and Q are all defined based on the sum of the principle minors (i.e. the rotation invariant I ₂) of the pressure tensor. We discuss in detail the problems of I ₂-based measures and explain why they may produce ambiguous and biased results. We introduce a new measure AG constructed based on the determinant of the pressure tensor (i.e. the rotation invariant I ₃) which does not suffer from the problems of I ₂-based measures. We compare AG with other measures in 2 and 3-dimension particle-in-cell magnetic reconnection simulations, and show that AG can effectively trace the EDR of reconnection in both Harris and force-free current sheets. On the other hand, A∅ _e does not show prominent peaks in the EDR and part of the separatrix in the force-free reconnection simulations, demonstrating that A∅ _e does not measure all the non-gyrotropic effects in this case, and is not suitable for studying magnetic reconnection in more general situations other than Harris sheet reconnection.

Normothermic machine perfusion for the assessment and transplantation of declined human kidneys from donation after circulatory death donors

BACKGROUND

A significant proportion of donation after circulatory death (DCD) kidneys are declined for transplantation because of concerns over their quality. Ex vivo normothermic machine perfusion (NMP) provides a unique opportunity to assess the quality of a kidney and determine its suitability for transplantation.

METHODS

In phase 1 of this study, declined human DCD kidneys underwent NMP assessment for 60 min. Kidneys were graded 1-5 using a quality assessment score (QAS) based on macroscopic perfusion, renal blood flow and urine output during NMP. In phase 2 of the study, declined DCD kidneys were assessed by NMP with an intention to transplant them.

RESULTS

In phase 1, 18 of 42 DCD kidneys were declined owing to poor in situ perfusion. After NMP, 28 kidneys had a QAS of 1-3, and were considered suitable for transplantation. In phase 2, ten of 55 declined DCD kidneys underwent assessment by NMP. Eight kidneys had been declined because of poor in situ flushing in the donor and five of these were transplanted successfully. Four of the five kidneys had initial graft function.

CONCLUSION

NMP technology can be used to increase the number of DCD kidney transplants by assessing their quality before transplantation.

Interventional dual-energy imaging-Feasibility of rapid kV-switching on a C-arm CT system

PURPOSE

In the last years, dual-energy CT imaging has shown clinical value, thanks to its ability to differentiate materials based on their atomic number and to exploit different properties of images acquired at two different energies. C-arm CT systems are used to guide procedures in the interventional suite. Until now, there are no commercially available systems that employ dual-energy material decomposition. This paper explores the feasibility of implementing a fast kV-switching technique on a clinically available angiographic system for acquiring dual-energy C-arm CT images.

METHODS

As an initial proof of concept, a fast kV-switching approach was implemented on an angiographic C-arm system and the peak tube voltage during 3D rotational scans was measured. The tube voltage measurements during fast kV-switching scans were compared to corresponding measurements on kV-constant scans. Additionally, to prove stability of the requested exposure parameters, the accuracy of the delivered tube current and pulse width were also recorded and compared. In a first phantom experiment, the voxel intensity values of the individual tube voltage components of the fast kV-switching scans were compared to their corresponding kV-constant scans. The same phantom was used for a simple material decomposition between different iodine concentrations and pure water using a fast kV-switching protocol of 81 and 125 kV. In the last experiment, the same kV-switching protocol as in the phantom scan was used in an in vivo pig study to demonstrate the clinical feasibility.

RESULTS

During rapid kV-switching acquisitions, the measured tube voltage of the x-ray tube during fast switching scans has an absolute deviation of 0.23 ± 0.13 kV compared to the measured tube voltage produced during kV-constant acquisitions. The stability of the peak tube voltage over different scan requests was about 0.10 kV for the low and 0.46 for the high energy kV-switching scans and less than 0.1 kV for kV-constant scans, indicating slightly lower stability for kV-switching scans. The tube current resulted in a relative deviation of -1.6% for the low and 6.6% overestimation for the high tube voltage of the kV-switching scans compared to the kV-constant scans. The pulse width showed no deviation for the longer pulse width and only minor deviations (0.02 ± 0.02 ms) for the shorter pulse widths compared to the kV-constant scans. The phantom experiment using different iodine concentrations showed an accurate correlation (R² > 0.99) between the extracted intensity values in the kV-switching and kV-constant reconstructed volumes, and allows for an automatic differentiation between contrast concentration down to 10% (350 mg/ml iodine) and pure water under low-noise conditions. Preliminary results of iodine and soft tissue separation showed also promising results in the first in vivo pig study.

CONCLUSIONS

The feasibility of dual-energy imaging using a fast kV-switching method on an angiographic C-arm CT system was investigated. Direct measurements of beam quality in the x-ray field demonstrate the stability of the kV-switching method. Phantom and in vivo experiments showed that images did not deviate from those of corresponding kV-constant scans. All performed experiments confirmed the capability of performing fast kV-switching scans on a clinically available C-arm CT system. More complex material decomposition tasks and postprocessing steps will be part of future investigations.

Deformation reconstruction by means of surface optimization. Part I: Time-averaged electronic speckle pattern interferometry

Electronic speckle pattern interferometry is a well-known experimental technique for full-field deformation measurements. Although speckle interferometry techniques were developed years ago and are widely used for the visualization of the operating deflection shapes of vibrating surfaces, methods for accurate reconstruction of the observed deflection shape are still an active topic of research. Determination of the relative phase of the motion of vibrating objects is especially difficult and normally phase maps are calculated by direct transformation of the experimentally obtained interferometric images. An alternative method of phase reconstruction is described that involves solving the inverse problem via surface optimization. Compared to previously developed optimization methods, this method offers a higher spatial resolution and is more suitable for analysis of complex vibration patterns.

Reduced perfusion in systemic sclerosis digital ulcers (both fingertip and extensor) can be increased by topical application of glyceryl trinitrate

Objectives

In patients with systemic sclerosis (SSc), fingertip digital ulcers (DUs) are believed to be ischaemic, and extensor surface DUs a result of mechanical factors/microtrauma. Our aim was to assess blood flow response to topical glyceryl trinitrate (GTN) compared to placebo in SSc DUs, looking for differences in pathophysiology between fingertip and extensor lesions.

Method

This was a double-blind, randomised, crossover, placebo-controlled study. Sixteen (6 fingertip, 10 extensor) DUs were each studied twice (one day apart): once with GTN and once with placebo ointment. Perfusion at the DU centre (‘DUCore’) and periphery (‘DUPeriphery’), as measured by laser Doppler imaging was performed before and immediately after ointment application, then every 10 min, up to 90 min post-application. We calculated the area under the response curve (AUC) and the ratio of peak perfusion to baseline, then compared these between GTN and placebo.

Results

Perfusion was lower in the DUCore compared to the DUPeriphery (ratio of 0.52). The microvessels of the DUCore were responsive to GTN, with an increase in perfusion, with a similar effect in both fingertip and extensor DUs. The AUC and peak/baseline perfusion difference in means (ratio, 95% confidence interval) between GTN and placebo at the DUCore were 1.2 (1.0–1.6) and 1.2 (1.0–1.5) respectively, and at the DUPeriphery were 1.1 (0.8–1.6) and 1.0 (0.9–1.2) respectively.

Conclusion

DUs (both fingertip and extensor) were responsive to topical GTN, with an increase in perfusion to the ischaemic DU centre. If both fingertip and extensor DUs have a (potentially reversible) ischaemic aetiology, this has important treatment implications.

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SSc fingertip DUs are believed to be ischaemic, whereas, extensor surface DUs are a result of mechanical factors/microtrauma.

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DUs (both fingertip and extensor) were responsive to topical GTN, in particular the ischaemic centre.

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If both fingertip and extensor DUs have a ischaemic aetiology, this has important treatment implications.

A branching process showing a phase transition

It is shown that a phase transition for the Ising model on a tree graph can be detected by the limiting behavior of the magnetization. The relevant limit theorems are special cases of limit theorems for multitype branching processes.

Toxicity Profiles in Rats Treated with Tumorigenic and Nontumorigenic Triazole Conazole Fungicides: Propiconazole, Triadimefon, and Myclobutanil

Conazoles are a class of azole based fungicides used in agriculture and as pharmaceutical products. They have a common mode of antifungal action through inhibition of ergosterol biosynthesis. Some members of this class have been shown to be hepatotoxic and will induce mouse hepatocellular tumors and/or rat thyroid follicular cell tumors. The particular mode of toxic and tumorigenic action for these compounds is not known, however it has been proposed that triadimefon-induced rat thyroid tumors arise through the specific mechanism of increased TSH. The present study was designed to identify commonalities of effects across the different conazoles and to determine unique features of the tissue responses that suggest a toxicity pathway and a mode of action for the observed thyroid response for triadimefon. Male Wistar/Han rats were treated with triadimefon (100, 500, 1800 ppm), propiconazole (100, 500, 2500 ppm), or myclobutanil (100, 500, 2000 ppm) in feed for 4, 30, or 90 days. The rats were evaluated for clinical signs, body and liver weight, histopathology of thyroid and liver, hepatic metabolizing enzyme activity, and serum T3, T4, TSH, and cholesterol levels. There was a dose-dependent increase in liver weight but not body weight for all treatments. The indication of cytochrome induction, pentoxyresorufin O-dealkylation (PROD) activity, had a dose-related increase at all time points for all conazoles. Uridine diphopho-glucuronosyl transferase (UDPGT), the T4 metabolizing enzyme measured as glucuronidation of 1-naphthol, was induced to the same extent after 30 and 90 days for all three conazoles. Livers from all high dose treated rats had centrilobular hepatocyte hypertrophy after 4 days, while only triadimefon and propiconazole treated rats had hepatocyte hypertrophy after 30 days, and only triadimefon treated rats had hepatocyte hypertrophy after 90 days. Thyroid follicular cell hypertrophy, increased follicular cell proliferation, and colloid depletion were present only after 30 days in rats treated with the high dose of triadimefon. A dose-dependent decrease in T4 was present after 4 days with all 3 compounds but only the high doses of propiconazole and triadimefon produced decreased T4 after 30 days. T3 was decreased after high-dose triadimefon after 4 days and in a dose-dependent manner for all compounds after 30 days. Thyroid hormone levels did not differ from control values after 90 days and TSH was not increased in any exposure group. A unique pattern of toxic responses was not identified for each conazole and the hypothesized mode of action for triadimefon-induced thyroid gland tumors was not supported by the data.

Toxicity Profiles in Mice Treated with Hepatotumorigenic and Non-Hepatotumorigenic Triazole Conazole Fungicides: Propiconazole, Triadimefon, and Myclobutanil

Conazoles comprise a class of fungicides used in agriculture and as pharmaceutical products. The fungicidal properties of conazoles are due to their inhibition of ergosterol biosynthesis. Certain conazoles are tumorigenic in rodents; both propiconazole and triadimefon are hepatotoxic and hepatotumorigenic in mice, while myclobutanil is not a mouse liver tumorigen. As a component of a large-scale study aimed at determining the mode(s) of action for tumorigenic conazoles, we report the results from comparative evaluations of liver and body weights, liver histopathology, cell proliferation, cytochrome P450 (CYP) activity, and serum cholesterol, high-density lipoprotein and triglyceride levels after exposure to propiconazole, triadimefon, and myclobutanil. Male CD-1 mice were treated in the feed for 4, 30, or 90 days with triadimefon (0, 100, 500, or 1800 ppm), propiconazole (0, 100, 500, or 2500 ppm) or myclobutanil (0, 100, 500, or 2000 ppm). Alkoxyresorufin O-dealkylation (AROD) assays indicated that all 3 chemicals induced similar patterns of dose-related increases in metabolizing enzyme activity. PROD activities exceeded those of MROD, and EROD with propiconazole inducing the highest activities of PROD. Mice had similar patterns of dose-dependent increases in hepatocyte hypertrophy after exposure to the 3 conazoles. High-dose exposures to propiconazole and myclobutanil, but not triadimefon, were associated with early (4 days) increases in cell proliferation. All the chemicals at high doses reduced serum cholesterol and high-density lipoprotein (HDL) levels at 30 days of treatment, while only triadimefon had this effect at 4 days of treatment and only myclobutanil and propiconazole at 90 days of treatment. Overall, the tumorigenic and nontumorigenic conazoles induced similar effects on mouse liver CYP enzyme activities and pathology. There was no specific pattern of tissue responses that could consistently be used to differentiate the tumorigenic conazoles, propiconazole, and triadimefon, from the nontumorigenic myclobutanil. These findings serve to anchor other transcriptional profiling studies aimed at probing differences in key events and modes of action for tumorigenic and nontumorigenic conazoles.

Methods of phase reconstruction for time-averaging electronic speckle pattern interferometry

Electronic speckle pattern interferometry is useful for the qualitative depiction of the deformation profile of harmonically vibrating objects. However, extending the process to achieve quantitative results requires unwrapping the phase in the interferogram, which contains significant noise due to the speckle. Two methods to achieve accurate phase information from time-averaged speckle pattern interferograms are presented. The first is based on a direct inverse of the regions within corresponding phase intervals, and the second is based on optimization of four independent parameters. The optimization method requires less time than more commonly used algorithms and shows higher precision of the resulting surface displacement.