Simulation of Auger decay dynamics in the hard X-ray regime: HCl as a showcase

Auger decay after photoexcitation or photoemission of an electron from a deep inner shell in the hard X-ray regime can be rather complex, implying a multitude of phenomena such as multiple-step cascades, post-collision interaction (PCI), and electronic state-lifetime interference. Furthermore, in a molecule nuclear motion can also be triggered. Here we discuss a comprehensive theoretical method which allows us to analyze in great detail Auger spectra measured around an inner-shell ionization threshold. HCl photoexcited or photoionized around the deep Cl 1s threshold is chosen as a showcase. Our method allows calculating Auger cross sections considering the nature of the ground, intermediate and final states (bound or dissociative), and the evolution of the relaxation process, including both electron and nuclear dynamics. In particular, we show that we can understand and reproduce a so-called experimental 2D-map, consisting of a series of resonant Auger spectra measured at different photon energies, therefore obtaining a detailed picture of all above-mentioned dynamical phenomena at once.

Occurrence of (suspected) genotoxic flavoring substances in Belgian alcohol-free beers

The regulatory landscape of flavorings is evolving, thereby putting pressure on control laboratories to develop analytical methods for a wide range of compounds in various types of food and drinks. In order to improve the monitoring of flavoring substances, a versatile and accurate analytical method using the solvent-assisted flavor evaporation (SAFE) technique coupled to GC-MS(SIM) was developed and validated. Focus was put on authorized flavoring substances requiring specific attention due to a genotoxic concern based on information from European risks assessment reports. Thirty-seven (suspected) genotoxic flavoring substances were analyzed in a selection of ten alcohol-free beers. Five suspected genotoxic compounds (i.e. 1-(2-furyl)-2-propanone, 2-acetylfuran, 2-acetyl-5-methylfuran, 2-acetyl-3,5-dimethylfuran, hex-2-eno-1,4-lactone) as well as two confirmed genotoxic flavoring substances (p-mentha-1,8-dien-7-al, 2,4-pentanedione) were identified and quantified among the selected samples. Low concentrations and natural occurrences of the identified compounds suggested that these were not added as such but rather originated from heat-treatments or from plant-based extracts.

Elecsys Cerebrospinal Fluid Assays Accurately Distinguish Alzheimer's Disease from Frontotemporal Lobar Degeneration

BACKGROUND

Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) are heterogeneous in their clinical presentation and underlying pathology, but they often have overlapping features. Diagnostic accuracy is critical for guiding patient management. Cerebrospinal fluid (CSF) diagnostic assays for the differentiation of AD and FTLD may increase diagnostic accuracy.

OBJECTIVES

In this study, we aimed to understand the potential role of CSF biomarkers and biomarker ratios, measured using Elecsys® CSF immunoassays (Roche Diagnostics International Ltd, Rotkreuz, Switzerland), in the differential diagnosis of AD and FTLD.

DESIGN

This study was conducted at a single center in Munich, Germany between July 2019 and July 2020. Patient CSF samples were retrospectively collected from the study center biobank.

PARTICIPANTS

A total of 130 patients with cognitive impairment were included in the study; 86 patients were diagnosed with AD and 44 with FTLD (behavioral variant frontotemporal dementia, semantic variant of primary progressive aphasia, and non-fluent variant of primary progressive aphasia), based on core clinical criteria and a non-CSF biomarker, a typical pattern of regional hypometabolism on [18F] fluorodeoxyglucose positron emission tomography.

MEASUREMENTS

Patient CSF biomarker concentrations were measured using Elecsys CSF immunoassays. Receiver operating characteristic analyses were conducted to determine areas under the curve (AUCs) for CSF biomarker performance. Sensitivity and specificity analyses were conducted to evaluate the performance of established cut-offs (Aβ42 ≤1000 pg/mL, pTau181/Aβ42 ratio >0.024, and tTau/Aβ42 ratio >0.28) and optimized cut-offs based on Youden's index.

RESULTS

AUC-based performance was similarly good for the pTau181/Aβ42 ratio (AUC=0.841; 95% CI: 0.759-0.923), pTau181/Aβ40 ratio (AUC=0.837; 95% CI: 0.754-0.919), Aβ42/Aβ40 ratio (AUC=0.829; 95% CI: 0.746-0.912), tTau/Aβ42 ratio (AUC=0.822; 95% CI: 0.736-0.908), pTau181/Aβ42/Aβ40 ratio (AUC=0.817; 95% CI: 0.734-0.901), and Aβ42 (AUC=0.812; 95% CI: 0.722-0.902). Performance was slightly lower for the tTau/Aβ42/Aβ40 ratio (AUC=0.799; 95% CI: 0.713-0.885), pTau181 alone (AUC=0.793; 95% CI: 0.707-0.880), tTau/Aβ40 ratio (AUC=0.751; 95% CI: 0.657-0.844), and tTau alone (AUC=0.706; 95% CI: 0.613-0.799). The highest qualitative performance was observed with the pTau181/Aβ42 ratio with an established cut-off value of >0.024 and optimized cut-off value of >0.022: sensitivity and specificity values were 0.892 and 0.773, respectively.

CONCLUSIONS

Elecsys CSF immunoassays demonstrate good diagnostic accuracy in differentiating patients with AD from those with FTLD. These immunoassays have the potential to support clinical decision making, i.e. in diagnosing patients with FTLD by excluding patients with amyloid positivity, which is indicative of underlying AD.

Vertebral osteomyelitis is characterised by increased RANK/OPG and RANKL/OPG expression ratios in vertebral bodies and intervertebral discs

Vertebral osteomyelitis (VO) is an infection of the spine mainly caused by bacterial pathogens. The pathogenesis leading to destruction of intervertebral discs (IVDs) and adjacent vertebral bodies (VBs) is poorly described. The present study aimed at investigating the connection between infection and bone/disc metabolism in VO patients. 14 patients with VO (infection group) and 14 patients with burst fractures of the spine (fracture group; control) were included prospectively. Tissue biopsies from affected IVDs and adjacent VBs were analysed by RT-qPCR for mRNA-expression levels of 18 target genes including chemokines, adipokines and genes involved in bone metabolism. Most importantly, the receptor activator of NF-κB/osteoprotegerin (RANK/OPG) expression ratio was drastically elevated in both VBs and IVDs of the infection group. In parallel, expression of genes of the prostaglandin-E2-dependent prostanoid system was induced. Such genes regulate tissue degradation processes via the triad OPG/RANK/RANKL as well as via the chemokines IL-8 and CCL-20, whose expression was also found to be increased upon infection. The gene expression of the adipokine leptin, which promotes inflammatory tissue degradation, was higher in IVD tissue of the infection group, whereas the transcription of omentin and resistin genes, whose functions are largely unknown in the context of infectious diseases, was lower in infected VBs. In summary, similar expression patterns of pro-inflammatory cytokines and pro-osteoclastogenic factors were identified in VBs and IVDs of patients suffering from VO. This suggests that common immuno-metabolic pathways are involved in the mechanisms leading to tissue degradation in VBs and IVDs during VO.

Factors associated with the appropriateness of antibiotics prescribed in French general practice: a cross-sectional study using reimbursement databases

OBJECTIVES

Identifying characteristics associated with the appropriateness of antibiotic prescriptions is useful to guide antibiotic stewardship interventions. Proxy indicators estimating the appropriateness of antibiotic prescriptions at the general practitioner (GP) level have recently been validated. Our objectives were to identify (a) clusters of GPs according to their appropriateness score based on these proxy indicator results, and (b) GPs', patients' and practices' characteristics associated with inappropriate prescriptions.

METHODS

We conducted a cross-sectional observational study analysing antibiotics prescribed by GPs in one large French region in 2019, using the Health Insurance databases. We identified clusters of GPs according to their appropriateness score calculated from ten proxy indicators' results. We then analysed the association between the clusters with more inappropriate practices compared with the one with less inappropriate practices, and GPs', patients', and practices' characteristics. We performed bivariate and multivariable analyses using logistic polytomous regressions.

RESULTS

We included 4819 GPs who were grouped into three clusters. GPs who belong to the clusters with more inappropriate practices were more likely to practice in certain geographical area, to be male, not to have a particular medical practice, to be practicing for longer, to have more patients and consultations, to have a higher proportion of elderly patients, and to prescribe more drugs, more antibiotics and a higher proportion of broad-spectrum antibiotics.

CONCLUSION

We identified clusters of practice as well as factors associated with the appropriateness of antibiotic prescriptions, using routinely collected data. This might help to guide antibiotic stewardship interventions.

Pulse Energy and Pulse Duration Effects in the Ionization and Fragmentation of Iodomethane by Ultraintense Hard X Rays

The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photoabsorptions, Auger decay, charge rearrangement, and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH_{3}I) by ultraintense (∼10^{19}  W/cm^{2}) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product's final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.

Quantity Metrics and Proxy Indicators to Estimate the Volume and Appropriateness of Antibiotics Prescribed in French Nursing Homes: A Cross-sectional Observational Study Based on 2018 Reimbursement Data

BACKGROUND

Antibiotic resistance is an increasing threat to public health globally. Indicators on antibiotic prescribing are required to guide antibiotic stewardship interventions in nursing homes. However, such indicators are not available in the literature. Our main objective was to provide a set of quantity metrics and proxy indicators to estimate the volume and appropriateness of antibiotic use in nursing homes.

METHODS

Recently published articles were first used to select quantity metrics and proxy indicators, which were adapted to the French nursing home context. A cross-sectional observational study was then conducted based on reimbursement databases. We included all community-based nursing homes of the Lorraine region in northeastern France. We present descriptive statistics for quantity metrics and proxy indicators. For proxy indicators, we also assessed performance scores, clinimetric properties (measurability, applicability, and room for improvement), and conducted case-mix and cluster analyses.

RESULTS

A total of 209 nursing homes were included. We selected 15 quantity metrics and 11 proxy indicators of antibiotic use. The volume of antibiotic use varied greatly between nursing homes. Proxy indicator performance scores were low, and variability between nursing homes was high for all indicators, highlighting important room for improvement. Six of the 11 proxy indicators had good clinimetric properties. Three distinct clusters were identified according to the number of proxy indicators for which the acceptable target was reached.

CONCLUSIONS

This set of 15 quantity metrics and 11 proxy indicators may be adapted to other contexts and could be used to guide antibiotic stewardship programs in nursing homes.

POS0678 DOES SILDENAFIL IMPROVE ENDOTHELIAL DYSFUNCTION IN RHEUMATOID ARTHRITIS? – A PILOT CLINICAL TRIAL

Background:

Rheumatoid arthritis (RA) is independently associated with an increased risk of cardiovascular disease (CVD). One of the early stages of atherosclerosis is endothelial dysfunction, which is increased in RA. Using drugs to target endothelial dysfunction is a promising novel strategy for CVD prevention in RA. Sildenafil has been shown to improve endothelial function in diabetics, who have similar increased CVD risk. Our hypothesis was that sildenafil use may be a novel primary CVD prevention strategy in RA.

Objectives:

To determine if sildenafil use in RA patients improves endothelial dysfunction (as measured by brachial artery flow-mediated dilation [FMD] and peripheral arterial tone [PAT]), as well as serum inflammatory and atherosclerosis biomarkers.

Methods:

This NIH-funded study was a phase II, randomized double-blind placebo-controlled crossover efficacy trial of 25 RA patients, with no known history of CVD, but at least one traditional CVD risk factor. Patients were randomized 1:1 to receive either sildenafil or placebo for 3 months, then after a 2-week washout, crossed over to each respective group for an additional 3 months. Vascular studies (FMD and PAT) and serum atherosclerosis biomarkers (e-Selectin, ICAM-1, VCAM-1) were performed at baseline, 3 months pre- and post-washout, and 6 months. Adverse events were collected. Given the cross-over design, analyses included a random effects model for within-subject comparisons of sildenafil versus placebo periods, adjusting for the baseline (FMD or EndoPAT) within that period and a term for treatment order. All tests were 2-sided with α=0.05.

Results:

A total of 233 subjects were assessed for eligibility, with 25 subjects being randomized after written informed consent. A total of 13 subjects were randomized to placebo first, and 12 to sildenafil first. Baseline characteristics were similar between those randomized to Placebo vs. Sildenafil first. Mean age was 62.0+/-10.9 years; 84% were female; and 92% were white. A total of 6 adverse events experienced in 3 subjects occurred. The primary endpoint (increase in %FMD in Sildenafil period vs. Placebo period) was not significant (p=0.19). However, note the study was powered at 80% to detect an effect size of 0.37 for change in %FMD or biomarker with a sample size of 60, not 25. However, sildenafil use was associated with a significant increase (improvement) by 0.200 units of PAT ratio (p=0.003) compared with placebo, adjusted by treatment order and baseline PAT ratio (within the given treatment period). Exploratory linear mixed models comparing e-Selectin, ICAM-1, and VCAM-1 between Sildenafil vs. Placebo periods, adjusted for treatment order and the baseline biomarker level, did not show any significant differences except for ICAM-1 (55.3 units higher in Sildenafil vs. Placebo periods, p=0.011).

Conclusion:

In this pilot trial of 25 RA subjects, sildenafil use was associated with a significant increase (improvement) in endothelial function as measured by PAT. However, there was no significant difference in FMD. The study is limited due to the small sample size, which was impacted by slow recruitment as well as the COVID-19 pandemic. Future larger studies are required to assess whether other PDE5 inhibitors may improve endothelial dysfunction in RA and other autoimmune disease patients at high risk of CVD.

References:

[1]Maradit-Kremers H, Crowson CS, Nicola PJ, et al. Increased unrecognized coronary heart disease and sudden deaths in rheumatoid arthritis: a population-based cohort study. Arthritis Rheum 2005;52:402-11.

[2]Peters MJ, van Halm VP, Voskuyl AE, et al. Does rheumatoid arthritis equal diabetes mellitus as an independent risk factor for cardiovascular disease? A prospective study. Arthritis Rheum 2009;61:1571-9.

[3]Deyoung L, Chung E, Kovac JR, et al. Daily use of sildenafil improves endothelial function in men with type 2 diabetes. J Andrology 2012;33:176-80.

Disclosure of Interests:

None declared

The O K-2V spectrum of CO: the influence of the second core-hole

Using synchrotron radiation in the tender X-ray regime, a photoelectron spectrum showing the formation of single site double-core-hole pre-edge states, involving the K shell of the O atom in CO, has been recorded by means of high-resolution electron spectroscopy. The experimentally observed structures have been simulated, interpreted and assigned, employing state-of-the-art ab initio quantum chemical calculations, on the basis of a theoretical model, accounting for their so-called direct or conjugate character. Features appearing above the double ionization threshold have been reproduced by taking into account the strong mixing between multi-excited and continuum states. The shift of the σ* resonance below the double ionization threshold, in combination with the non-negligible contributions of multi-excited configurations in the final states reached, gives rise to a series of avoided crossings between the different potential energy curves.

Impact of an Education Programme on IBD Patients' Skills: Results of a Randomised Controlled Multicentre Study [ECIPE]

BACKGROUND

Better patient knowledge on inflammatory bowel disease [IBD] could improve outcome and quality of life. The aim of this study was to assess if an education programme improves IBD patients' skills as regards their disease.

METHODS

The GETAID group conducted a prospective multicentre randomised controlled study. IBD patients were included at diagnosis, or after a significant event in the disease course. Patients were randomised between 'educated' or control groups for 6 months. Education was performed by trained health care professionals. A psycho-pedagogic score [ECIPE] was evaluated by a 'blinded' physician at baseline and after 6 and 12 months [M6 and M12]. The primary endpoint was the increase of ECIPE score at M6 of more than 20%.

RESULTS

A total of 263 patients were included in 19 centres (male:40%; median age:30.8; Crohn's disease [CD]:73%). Of these, 133 patients were randomised into the educated group and 130 into the control group. The median relative increase in ECIPE score at M6 was higher in the educated group as compared with the control group (16.7% [0-42.1%] vs 7% [0-18.8%], respectively, p = 0.0008). The primary endpoint was met in 46% vs 24% of the patients in the educated and control groups, respectively [p = 0.0003]. A total of 92 patients met the primary endpoint. In multivariate analysis, predictors of an increase of at least 20% of the ECIPE score were randomisation in the educated group (odds ratio [OR] = 2.59) and no previous surgery [OR = 1.92].

CONCLUSIONS

These findings support the set-up of education programmes in centres involved in the management of IBD patients.

Bedside ultrasound assessments of jugular venous compliance to track central venous pressure change during the treatment of decompensated heart failure

Background

Accurate volume status assessment is crucial for the treatment of acute decompensated heart failure (ADHF). Volume status assessment by physical exam is inaccurate, necessitating invasive measurement with right heart catheterization (RHC), which carries safety, pragmatic (scheduling, holding anticoagulants, etc) and financial burdens. Therefore, a reliable, non-invasive, cost-effective alternative is desired. Previously, we developed an ultrasound (US) based technique to measure internal jugular vein (IJV) compliance during RHC which was used for single time point central venous pressure (CVP) predictions. We now aim to apply this technique to track acute changes in CVP during diuresis for ADHF in patients with an in-dwelling pulmonary artery catheter.

Purpose

The objective of our study was to devise a rapid, portable and reliable alternative to RHC to track acute volume changes during treatment of ADHF.

Methods

We used an observational, prospective study design and recruited 15 patients from the CCU between 7/19–12/19 being treated for ADHF (systolic or diastolic) with IV diuretics +/−inotropic agents who underwent PA catheter insertion for continuous CVP monitoring. 13 of 15 patients received milrinone infusions. US images of the IJV were obtained at end expiration and during the strain phase of Valsalva at multiple 2–3 hr intervals. Change in IJV cross sectional area (ImageJ) was used as a measure of IJV compliance. Patients unable to perform the Valsalva maneuver and on mechanical circulatory support were excluded.

Results

Calculated % change in CSA of IJV was plotted against CVP. An inverse relationship was observed between CVP and % change in CSA of IJV. The data was fit with an inverse exponential regression shown in Figure 1 (R2=0.36, root mean square error = 3.19). Fivefold cross validation showed a stable model for predicting CVP based CSA (R2=0.34, root mean square error = 3.26)

Conclusion

Serial portable US assessment of IJV compliance can act a surrogate measure of CVP and,therefore, can provide reliable information on acute hemodynamic changes in ADHF.

Funding Acknowledgement

Type of funding source: None

[Puffy hand syndrome: A little-known diagnosis]

INTRODUCTION

Puffy hand syndrome is a rare complication of intravenous drug addiction. Diagnosis is based on the patient's history and clinical examination.

OBSERVATIONS

A woman and two men, aged 42, 39 and 36 years old, are described. All had a history of intravenous drug use of heroin and oral buprenorphine misuse. Puffy hand syndrome appeared during drug addiction (n = 2) or after its withdrawal (n = 1). It was associated with acrocyanosis (n = 1) or injection scars (n = 1). Upper limb ultrasonography showed sequelae of venous (n = 3) or arterial (n = 1) thrombosis. An upper limb lymphoscintigraphy in one patient showed decreased radionuclide uptake of axillary lymph node and subdermal reflux tracer in the forearm. Treatment was based on low-stretch bandages to reduce the volume and then elastic compression sleeve for long-term stabilization.

CONCLUSION

Puffy hand syndrome seen in intravenous drug addicts is poorly understood. It is a chronic complication despite the cessation of drug use. This syndrome has to become more widely known because its management is mandatory, although symptomatic.

Resonant Inelastic X-Ray Scattering Reveals Hidden Local Transitions of the Aqueous OH Radical

Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate ultrafast dynamics in liquids. Here we use RIXS to study the fundamentally and practically important hydroxyl radical in liquid water, OH(aq). Impulsive ionization of pure liquid water produced a short-lived population of OH(aq), which was probed using femtosecond x-rays from an x-ray free-electron laser. We find that RIXS reveals localized electronic transitions that are masked in the ultraviolet absorption spectrum by strong charge-transfer transitions-thus providing a means to investigate the evolving electronic structure and reactivity of the hydroxyl radical in aqueous and heterogeneous environments. First-principles calculations provide interpretation of the main spectral features.