Iron Kβ X-ray Emission Spectroscopy: The Origin of Spectral Features from Atomic to Molecular Systems Using Multi-configurational Calculations

Kβ X-ray emission spectroscopy (XES) is widely used to fingerprint the local spin of transition-metal ions, including in pump-probe experiments, to identify excited states or in chemical and biological reactions to characterize short-lived intermediates. In this study, the spectra of ferrous and ferric complexes for various spin states were measured experimentally and described theoretically through restricted active space (RAS) calculations including dynamic correlations. Through the RAS calculations from simple atomic models to complex molecular systems, spectral effects such as the exchange interactions, crystal-field strength, and covalent orbital mixing were evaluated and discussed. The calculations find that only the spectral features of low-spin cases show a dependence on the crystal-field strength, particularly for ferrous low spin. The effect of the covalent orbital mixing strength on the first moment of the Kβ1,3 main line and the Kβ1,3-Kβ' energy splitting is quantitatively described. Clear relationships are found within a given nominal spin but less between different spin states, which calls for careful selection of reference spectra in future experiments. This study further advances our understanding of the correlation between changes in experimental spectral features and their corresponding electronic structure information.

Genetic screening of South African families with Parkinson's disease

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Cost-Effectiveness of Prevention for People at Risk for Dementia: A Scoping Review and Qualitative Synthesis

Dementia is from an economic perspective a main challenge for economies worldwide because of increasing costs. Since there is no cure in sight, prevention seems the most promising approach for reducing health care cost due to Dementia. On the contrary, approximately 40% of dementias is attributable to modifiable risk factors and first studies showed that multidomain interventions may be effective for preventing dementia. Considering the increasing economic burden, for many health administrations worldwide, cost-effectiveness plays a mayor role. This scoping review wants to bring evidence to the question if prevention for people at risk may be cost-effective. Therefore, the four databases Medline (via Pubmed), CINHAL (via EBSCO), Business Source Complete (via EBSCO), and the Health Economic Evaluation database (HEED) were used to conduct a scoping review using PICO and a systematic search string. 3,629 studies were identified and seven met all inclusion criteria. The included studies showed clear cost-effectiveness for most multidomain interventions. The gained QALYs at mean were 0.08 (SD=0.08) and the intervention average costs 472.20 EUR per Person (SD=74.06 EUR). The Incremental Cost-Effectiveness Ratios varied between -80,427.97 and 104,189.82 EUR per QALY. The three core results are (i) prevention programs focusing on people at risk may be cost-effective and cost-efficient, (ii) multimodal prevention reveal cost saving potential, when the people at risk are defined well, (iii prevention in middle-aged cohorts may be also cost-effective if life-style related risk factors are addressed.

X-ray Spectroscopic Study of the Electronic Structure of a Trigonal High-Spin Fe(IV)═O Complex Modeling Non-Heme Enzyme Intermediates and Their Reactivity

Fe K-edge X-ray absorption spectroscopy (XAS) has long been used for the study of high-valent iron intermediates in biological and artificial catalysts. 4p-mixing into the 3d orbitals complicates the pre-edge analysis but when correctly understood via 1s2p resonant inelastic X-ray scattering and Fe L-edge XAS, it enables deeper insight into the geometric structure and correlates with the electronic structure and reactivity. This study shows that in addition to the 4p-mixing into the 3dz2 orbital due to the short iron-oxo bond, the loss of inversion in the equatorial plane leads to 4p mixing into the 3dx2-y2,xy, providing structural insight and allowing the distinction of 6- vs 5-coordinate active sites as shown through application to the Fe(IV)═O intermediate of taurine dioxygenase. Combined with O K-edge XAS, this study gives an unprecedented experimental insight into the electronic structure of Fe(IV)═O active sites and their selectivity for reactivity enabled by the π-pathway involving the 3dxz/yz orbitals. Finally, the large effect of spin polarization is experimentally assigned in the pre-edge (i.e., the α/β splitting) and found to be better modeled by multiplet simulations rather than by commonly used time-dependent density functional theory.

Tuning the Type 1 Reduction Potential of Multicopper Oxidases: Uncoupling the Effects of Electrostatics and H-Bonding to Histidine Ligands

In multicopper oxidases (MCOs), the type 1 (T1) Cu accepts electrons from the substrate and transfers these to the trinuclear Cu cluster (TNC) where O₂ is reduced to H₂O. The T1 potential in MCOs varies from 340 to 780 mV, a range not explained by the existing literature. This study focused on the ∼350 mV difference in potential of the T1 center in Fet3p and Trametes versicolor laccase (TvL) that have the same 2His1Cys ligand set. A range of spectroscopies performed on the oxidized and reduced T1 sites in these MCOs shows that they have equivalent geometric and electronic structures. However, the two His ligands of the T1 Cu in Fet3p are H-bonded to carboxylate residues, while in TvL they are H-bonded to noncharged groups. Electron spin echo envelope modulation spectroscopy shows that there are significant differences in the second-sphere H-bonding interactions in the two T1 centers. Redox titrations on type 2-depleted derivatives of Fet3p and its D409A and E185A variants reveal that the two carboxylates (D409 and E185) lower the T1 potential by 110 and 255-285 mV, respectively. Density functional theory calculations uncouple the effects of the charge of the carboxylates and their difference in H-bonding interactions with the His ligands on the T1 potential, indicating 90-150 mV for anionic charge and ∼100 mV for a strong H-bond. Finally, this study provides an explanation for the generally low potentials of metallooxidases relative to the wide range of potentials of the organic oxidases in terms of different oxidized states of their TNCs involved in catalytic turnover.

Are you better than me? Social comparisons in carrion crows (Corvus corone)

Comparing oneself to others is a key process in humans that allows individuals to gauge their performances and abilities and thus develop and calibrate their self-image. Little is known about its evolutionary foundations. A key feature of social comparison is the sensitivity to other individuals' performance. Recent studies on primates produced equivocal results, leading us to distinguish between a 'strong' variant of the social comparison hypothesis formulated for humans and a 'weak' variant found in non-human primates that would comprise some elements of human social comparison. Here, we focus on corvids that are distantly related to primates and renowned for their socio-cognitive skills. We were interested in whether crows' task performances were influenced (i) by the presence of a conspecific co-actor performing the same discrimination task and (ii) by the simulated acoustic cues of a putative co-actor performing better or worse than themselves. Crows reached a learning criterion quicker when tested simultaneously as compared to when tested alone, indicating a facilitating effect of social context. The performance of a putative co-actor influenced their performance: crows were better at discriminating familiar images when their co-actor was better than they were. Standard extremity (how pronounced the difference was between the performance of the subject and that of the co-actor), and category membership (affiliation status and sex), of the putative co-actors had no effect on their performance. Our findings are in line with the 'weak' variant of social comparison and indicate that elements of human social comparison can be found outside of primates.

Methane Activation by a Mononuclear Copper Active Site in the Zeolite Mordenite: Effect of Metal Nuclearity on Reactivity

The direct conversion of methane to methanol would have a wide reaching environmental and industrial impact. Copper-containing zeolites can perform this reaction at low temperatures and pressures at a previously defined O₂-activated [Cu₂O]²⁺ site. However, after autoreduction of the copper-containing zeolite mordenite and removal of the [Cu₂O]²⁺ active site, the zeolite is still methane reactive. In this study, we use diffuse reflectance UV-vis spectroscopy, magnetic circular dichroism, resonance Raman spectroscopy, electron paramagnetic resonance, and X-ray absorption spectroscopy to unambiguously define a mononuclear [CuOH]⁺ as the CH₄ reactive active site of the autoreduced zeolite. The rigorous identification of a mononuclear active site allows a reactivity comparison to the previously defined [Cu₂O]²⁺ active site. We perform kinetic experiments to compare the reactivity of the [CuOH]⁺ and [Cu₂O]²⁺ sites and find that the binuclear site is significantly more reactive. From the analysis of density functional theory calculations, we elucidate that this increased reactivity is a direct result of stabilization of the [Cu₂OH]²⁺ H-atom abstraction product by electron delocalization over the two Cu cations via the bridging ligand. This significant increase in reactivity from electron delocalization over a binuclear active site provides new insights for the design of highly reactive oxidative catalysts.

The relationship between the recognition of specific basic emotions and negative symptom domains in patients with schizophrenia spectrum disorders

Introduction

Current research suggests emotion recognition to be significantly impaired in individuals with schizophrenia spectrum disorders (SSD), whereby negative symptoms are theorised to play a crucial role. Emotion recognition deficits are assumed to be predictors of transition from clinical high risk to schizophrenia. So far, little attention has been given hereby to the subdomains of negative symptoms and recognizing the individual basic emotions.

Objectives

Our study aimed to explore the relationship between the recognition of the basic emotions and each negative symptom domain.

Methods

66 patients with a SSD diagnosis were recruited at the Charité – Universitätsmedizin Berlin. Correlational and regression analyses to control for the covariates (age, education, sex) were conducted between the recognition of the six basic emotions (anger, disgust, fear, happiness, sadness, surprise) using the Emotion Recognition Task of the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the seven different subdomains of negative symptoms of the Positive and Negative Syndrome Scale (PANSS).

Results

revealed significantly negative correlations of blunted affect with the recognition of happiness, fear, and disgust. Difficulties in abstract thinking, also correlated positively with the recognition of fear. Additionally, we found a significant positive correlation between stereotyped thinking and difficulties in abstract thinking with the response latency in emotion recognition.

Conclusions

Individuals with SSD and domains of negative symptoms showed specific impairments in recognizing the representation of basic emotions. A longitudinal design to make causality statements would be useful for future research. Moreover, emotion recognition should be considered for early detection and individualized treatment.

Disclosure

No significant relationships.

Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer. Corrigendum

A figure in the article by Huyke et al. [(2021), J. Synchrotron Rad. 28, 1100-1113] is corrected.

S K-edge XAS of CuII, CuI, and ZnII oxidized Dithiolene complexes: Covalent contributions to structure and the Jahn-Teller effect

Reduced dithiolene ligands are bound to high valent Mo centers in the active site of the oxotransferase family of enzymes. Related model complexes have been studied with great insight by Prof. Holm and his colleagues. This study focuses on the other limit of dithiolene chemistry: an investigation of the 2-electron oxidized dithiolene bound to low-valent late transition metal (TM) ions (ZnII, CuI, and CuII). The bonding descriptions of the oxidized dithiolene [N,N-dimethyl piperazine 2,3-dithione (Me2Dt0)] complexes are probed using S K-edge X-ray absorption spectroscopy (XAS) and the results are correlated to density functional theory (DFT) calculations. These experimentally supported calculations are then extended to explain the different geometric structures of the three complexes. The ZnII(Me2Dt0)2 complex has only ligand-ligand repulsion so it is stabilized at the D2d symmetry limit. The CuI(Me2Dt0)2 complex has additional weak backbonding thus distorts somewhat from D2d toward D2h symmetry. The CuII(Me2Dt0)2 complex has a strong σ donor bond that leads to both a large Jahn-Teller stabilization to D2h and an additional covalent contribution to the geometry. The combined strong stabilization results in the square planar, D2h structure. This study quantifies the competition between the ligand-ligand repulsion and the change in electronic structures in determining the final geometric structures of the oxidized dithiolene complexes, and provides quantitative insights into the Jahn-Teller stabilization energy and its origin.

Increasing sample diversity in psychiatric genetics - Introducing a new cohort of patients with schizophrenia and controls from Vietnam - Results from a pilot study

OBJECTIVES

Genome-Wide Association Studies (GWAS) of Schizophrenia (SCZ) have provided new biological insights; however, most cohorts are of European ancestry. As a result, derived polygenic risk scores (PRS) show decreased predictive power when applied to populations of different ancestries. We aimed to assess the feasibility of a large-scale data collection in Hanoi, Vietnam, contribute to international efforts to diversify ancestry in SCZ genetic research and examine the transferability of SCZ-PRS to individuals of Vietnamese Kinh ancestry.

METHODS

In a pilot study, 368 individuals (including 190 SCZ cases) were recruited at the Hanoi Medical University's associated psychiatric hospitals and outpatient facilities. Data collection included sociodemographic data, baseline clinical data, clinical interviews assessing symptom severity and genome-wide SNP genotyping. SCZ-PRS were generated using different training data sets: (i) European, (ii) East-Asian and (iii) trans-ancestry GWAS summary statistics from the latest SCZ GWAS meta-analysis.

RESULTS

SCZ-PRS significantly predicted case status in Vietnamese individuals using mixed-ancestry (R² liability = 4.9%, p = 6.83 × 10^-8), East-Asian (R² liability = 4.5%, p = 2.73 × 10^-7) and European (R² liability = 3.8%, p = 1.79 × 10^-6) discovery samples.

DISCUSSION

Our results corroborate previous findings of reduced PRS predictive power across populations, highlighting the importance of ancestral diversity in GWA studies.

Histopathologic spectrum of glomangioma: A clinico-pathologic review

Introduction/Objective

Glomus tumors are mesenchymal neoplasms with glomus body type modified smooth muscle cell differentiation. Most glomus tumors have a benign clinical course. However, rarely, they display malignant histologic features.

Methods/Case Report

We undertook a retrospective study using a natural language search in CoPath to find surgical pathology cases from 1993-2020 containing “glomus” in the pathology diagnosis. All relevant cases were included, and clinicopathologic data were reviewed in detail.

Results (if a Case Study enter NA)

A total of 66 tumors were identified, of which 42 were in female (63.6%) and 24 in male (36.4%) patients. The age at surgery ranged from 22 to 79 years with a median of 47.5. Females were significantly younger than males at presentation (p=0.025) by 8.8±3.8 years. Forty cases (60.6%) were located on the digits, 24 in nonvisceral soft tissue of extremities, trunk, and lip (36.4%), and one each in stomach and breast parenchyma. Sixty-three (95.5%) were benign (of which one recurred locally), 2 (3%) were malignant, and 1 (1.5%) was atypical. Four (6%) were multicentric. One case showed mixed histology (oncocytic and classic features) and one was classified as glomangiomatosis. The malignant cases each presented with a single tumor in lower extremity soft tissue in female patients (aged 33 and 49 years). The tumors measured 0.5 and 1.8 cm respectively and showed marked cytologic atypia in both and increased mitotic activity in the first. They were both completely excised.

Conclusion

The majority of glomus tumors are benign, however 3% are malignant. The most common location is the digits, followed by soft tissue. This tumor is more commonly seen in female patients. Unusual histologic variants such as glomangiomatosis and oncocytic component at times may create some difficulty to reach the diagnosis, especially on small biopsies. Unusual locations such as stomach can lead to a wrong diagnosis such as carcinoid, especially in a small biopsy material.

Nuclear Resonance Vibrational Spectroscopic Definition of the Fe(IV)2 Intermediate Q in Methane Monooxygenase and Its Reactivity

Methanotrophic bacteria utilize the nonheme diiron enzyme soluble methane monooxygenase (sMMO) to convert methane to methanol in the first step of their metabolic cycle under copper-limiting conditions. The structure of the sMMO Fe(IV)₂ intermediate Q responsible for activating the inert C-H bond of methane (BDE = 104 kcal/mol) remains controversial, with recent studies suggesting both "open" and "closed" core geometries for its active site. In this study, we employ nuclear resonance vibrational spectroscopy (NRVS) to probe the geometric and electronic structure of intermediate Q at cryogenic temperatures. These data demonstrate that Q decays rapidly during the NRVS experiment. Combining data from several years of measurements, we derive the NRVS vibrational features of intermediate Q as well as its cryoreduced decay product. A library of 90 open and closed core models of intermediate Q is generated using density functional theory to analyze the NRVS data of Q and its cryoreduced product as well as prior spectroscopic data on Q. Our analysis reveals that a subset of closed core models reproduce these newly acquired NRVS data as well as prior data. The reaction coordinate with methane is also evaluated using both closed and open core models of Q. These studies show that the potent reactivity of Q toward methane resides in the "spectator oxo" of its Fe(IV)₂O₂ core, in contrast to nonheme mononuclear Fe(IV)═O enzyme intermediates that H atoms abstract from weaker C-H bonds.

ChemPix: automated recognition of hand-drawn hydrocarbon structures using deep learning

Inputting molecules into chemistry software, such as quantum chemistry packages, currently requires domain expertise, expensive software and/or cumbersome procedures. Leveraging recent breakthroughs in machine learning, we develop ChemPix: an offline, hand-drawn hydrocarbon structure recognition tool designed to remove these barriers. A neural image captioning approach consisting of a convolutional neural network (CNN) encoder and a long short-term memory (LSTM) decoder learned a mapping from photographs of hand-drawn hydrocarbon structures to machine-readable SMILES representations. We generated a large auxiliary training dataset, based on RDKit molecular images, by combining image augmentation, image degradation and background addition. Additionally, a small dataset of ∼600 hand-drawn hydrocarbon chemical structures was crowd-sourced using a phone web application. These datasets were used to train the image-to-SMILES neural network with the goal of maximizing the hand-drawn hydrocarbon recognition accuracy. By forming a committee of the trained neural networks where each network casts one vote for the predicted molecule, we achieved a nearly 10 percentage point improvement of the molecule recognition accuracy and were able to assign a confidence value for the prediction based on the number of agreeing votes. The ensemble model achieved an accuracy of 76% on hand-drawn hydrocarbons, increasing to 86% if the top 3 predictions were considered.

Millisecond timescale reactions observed via X-ray spectroscopy in a 3D microfabricated fused silica mixer

Determination of electronic structures during chemical reactions remains challenging in studies which involve reactions in the millisecond timescale, toxic chemicals, and/or anaerobic conditions. In this study, a three-dimensionally (3D) microfabricated microfluidic mixer platform that is compatible with time-resolved X-ray absorption and emission spectroscopy (XAS and XES, respectively) is presented. This platform, to initiate reactions and study their progression, mixes a high flow rate (0.50-1.5 ml min^-1) sheath stream with a low-flow-rate (5-90 µl min^-1) sample stream within a monolithic fused silica chip. The chip geometry enables hydrodynamic focusing of the sample stream in 3D and sample widths as small as 5 µm. The chip is also connected to a polyimide capillary downstream to enable sample stream deceleration, expansion, and X-ray detection. In this capillary, sample widths of 50 µm are demonstrated. Further, convection-diffusion-reaction models of the mixer are presented. The models are experimentally validated using confocal epifluorescence microscopy and XAS/XES measurements of a ferricyanide and ascorbic acid reaction. The models additionally enable prediction of the residence time and residence time uncertainty of reactive species as well as mixing times. Residence times (from initiation of mixing to the point of X-ray detection) during sample stream expansion as small as 2.1 ± 0.3 ms are also demonstrated. Importantly, an exploration of the mixer operational space reveals a theoretical minimum mixing time of 0.91 ms. The proposed platform is applicable to the determination of the electronic structure of conventionally inaccessible reaction intermediates.

Introducing a psychiatric genetic cohort of schizophrenia patients and controls from Vietnam

Introduction

Genome-wide association studies (GWAS) have successfully revealed genetic risk variants for schizophrenia (SCZ). However, the vast majority of GWAS largely comprise European samples. As a result, the derived polygenic risk scores (PRS) show decreased predictive power when applied to non-European populations.

Objectives

A long-term scientific cooperation between the Charité Universitätsmedizin Berlin and the Hanoi Medical University aims to address this limitation by recruiting a large genetic cohort of comprehensively phenotyped schizophrenia patients and controls in Vietnam.

Methods

A pilot study was conducted at the Department of Psychiatry of the Medical University Hanoi in 2017. Data collection encompassed i) genome-wide SNP genotyping of 200 schizophrenia patients and 200 control subjects ii) structured interviews to assess symptom severity (PANSS), iii) clinical parameters (e.g. duration of illness, medication) and demography.

Results

SCZ-PRS of the pilot sample (N=400) were generated using different training data sets: i) European, ii) East-Asian and iii) mixed GWAS summary statistics from the Psychiatric Genomics Consortium’s latest discovery sample. Most variance explained was observed using a mixed discovery sample (R²liability=0.053, p=3.11*10^-8, Pd <0.5), followed by PRS based on the East-Asian summary statistics (R²liability=0.0503, p=6.78*10^-8, Pd <1) and the European sample (R²liability=0.0363, p = 4.26*10^-6, Pd <0.01).

Conclusions

With this pilot project we established an efficient recruitment, genotyping and data analysis pipeline. Our results corroborate previous findings indicating that transferability of PRS across populations depends on the ancestral composition of the initial discovery dataset. We therefore aim to expand data collection efforts in the future in order to improve risk prediction across diverse populations.

Disclosure

No significant relationships.

Effect of 3d/4p Mixing on 1s2p Resonant Inelastic X-ray Scattering: Electronic Structure of Oxo-Bridged Iron Dimers

1s2p resonant inelastic X-ray scattering (1s2p RIXS) has proven successful in the determination of the differential orbital covalency (DOC, the amount of metal vs ligand character in each d molecular orbital) of highly covalent centrosymmetric iron environments including heme models and enzymes. However, many reactive intermediates have noncentrosymmetric environments, e.g., the presence of strong metal-oxo bonds, which results in the mixing of metal 4p character into the 3d orbitals. This leads to significant intensity enhancement in the metal K-pre-edge and as shown here, the associated 1s2p RIXS features, which impact their insight into electronic structure. Binuclear oxo bridged high spin Fe(III) complexes are used to determine the effects of 4p mixing on 1s2p RIXS spectra. In addition to developing the analysis of 4p mixing on K-edge XAS and 1s2p RIXS data, this study explains the selective nature of the 4p mixing that also enhances the analysis of L-edge XAS intensity in terms of DOC. These 1s2p RIXS biferric model studies enable new structural insight from related data on peroxo bridged biferric enzyme intermediates. The dimeric nature of the oxo bridged Fe(III) complexes further results in ligand-to-ligand interactions between the Fe(III) sites and angle dependent features just above the pre-edge that reflect the superexchange pathway of the oxo bridge. Finally, we present a methodology that enables DOC to be obtained when L-edge XAS is inaccessible and only 1s2p RIXS experiments can be performed as in many metalloenzyme intermediates in solution.

Reform design, institutional and workforce factors affecting the pace of change

Background

When implementing health care reforms the pace of change is often lacking behind the expectations of policy makers. This research is exploring in-depth the experiences of a primary care initiative from the perspective of general practitioners. The physicians' perspectives on design features, supporting environment and acceptance of the pilot are being explored. Enabling and constraining factors that may influence the pace of change of health care reforms are identified. Implications can be drawn for the strategic planning and smooth implementation of the change process.

Methods

14 problem-focused interviews with general practitioners working in pilot projects and 2 focus group discussions with 4-6 general practitioners working in single practices have been conducted. In addition, document analysis of secondary qualitative data and relevant policy documents has been conducted.

Results

Analysis revealed 9 codes: (1) Status of the general practitioner; (2) Institutional and legal framework; (3) Between cooperation and competition; (4) Hesitation from the young generation; (5) Reluctance from sole practitioners; (6) Personal drivers for starting a pilot (7) Challenges during set-up phase; (8) Challenges during growth phase; (9) Working conditions in primary care pilot projects. Enabling factors were a strong desire to be pioneering primary care provision and improved working conditions. The main constraining factors were low status of the general practitioner, uncertainty about future directions, lack of information and advice, high perceived financial risk, fear of losing autonomy and uncertainty about functioning teamwork.

Conclusions

For a smooth implementation of the primary care reform, system changes should improve education and training, compensation schemes and competence profiles of the professional groups involved. Further, initiatives should provide information and advice for practitioners striving for participating in a pilot project.

Key messages

The success of health care reforms also depends on institutional and workforce factors that may affect the pace of change. Health care reforms need strategic planning for a smooth implementation.

Structural properties of ultra-small thorium and uranium dioxide nanoparticles embedded in a covalent organic framework

We report the structural properties of ultra-small ThO2 and UO2 nanoparticles (NPs), which were synthesized without strong binding surface ligands by employing a covalent organic framework (COF-5) as an inert template. The resultant NPs were used to observe how structural properties are affected by decreasing grain size within bulk actinide oxides, which has implications for understanding the behavior of nuclear fuel materials. Through a comprehensive characterization strategy, we gain insight regarding how structure at the NP surface differs from the interior. Characterization using electron microscopy and small-angle X-ray scattering indicates that growth of the ThO2 and UO2 NPs was confined by the pores of the COF template, resulting in sub-3 nm particles. X-ray absorption fine structure spectroscopy results indicate that the NPs are best described as ThO2 and UO2 materials with unpassivated surfaces. The surface layers of these particles compensate for high surface energy by exhibiting a broader distribution of Th-O and U-O bond distances despite retaining average bond lengths that are characteristic of bulk ThO2 and UO2. The combined synthesis and physical characterization efforts provide a detailed picture of actinide oxide structure at the nanoscale, which remains highly underexplored compared to transition metal counterparts.

P1836 Common carotid artery intima-media thickness correlates with the epicardial fat thickness in patients with ischemic stroke

Purpose

The aim of this study was to determine the relationship between common carotid artery intima–media thickness (CCA-IMT), the resistance index (RI) in the vertebral and carotid arteries and epicardial fat thickness (EFT) in patients with ischemic stroke.

Methods

98 patients with ischemic stroke (31 females and 67 males, mean age was 68.2 ± 12.1 years) were studied. All patients had arterial hypertension (AH). Most of them (96.9%) had grade 3 hypertension according to ESH/ESC Guidelines for the management of arterial hypertension, 2018. Forty-two (43.1%) patients had coronary artery disease and 35 (35.4%) - atrial fibrillation (AF). The exclusion criteria was the presence of chronic obstructive pulmonary disease or other diseases associated with pulmonary hypertension. Patients were categorized according to National Institutes of Health Stroke Scale (NIHSS) severity in mild NIHSS (≤8) - 54 (55.1%) patients, moderate NIHSS (9–15) - 23 (23.5%) patients, and severe stroke NIHSS (≥16) - 21 (21.4%) patients. Median NIHSS score was 11.2 ± 1.7. All patients underwent a transthoracic echocardiography and a carotid ultrasound examination.

Results

The common carotid artery intima–media thickness correlated with EFT (r =0.78, p &lt; 0.001), the body mass index (r = 0.7, p &lt; 0.001) and systolic blood pressure (r = 0.25, p = 0.045). The resistance index in the vertebral and carotid arteries correlated only with EFT (r = 0.7, p &lt; 0.001 and r = 0.78, p &lt; 0.001, respectively) and body mass index (r = 0.58, p &lt; 0.001 and r = 0.68, p &lt; 0.001, respectively).

A multiple regression analysis in which the CCA-IMT was a dependent variable and age, body mass index, systolic blood pressure, blood cholesterol level and epicardial fat thickness were independent variables, showed that CCA-IMT was independently correlated with blood cholesterol level (β=0.714, р&lt;0.001) and EFT (β =0.255, р=0.002) in patients with ischemic stroke.

Conclusions

The common carotid artery intima–media thickness and parameters of the arterial stiffness of the extracranial vessels of the head are associated with the epicardial fat thickness and blood cholesterol level in patients with ischemic stroke. The common carotid artery intima–media thickness does not depend on age, gender, body mass index, systolic and diastolic blood pressure in patients with ischemic stroke.

P1837 The severity of acute ischemic stroke is associated with the right heart remodeling in patients with arterial hypertension

Purpose

The aim of this study was to determine the relationship of echocardiographic signs of the right heart remodeling and the stroke severity in patients with arterial hypertension and ischemic stroke.

Methods

98 patients with acute ischemic stroke (31 females and 67 males, mean age was 68.2 ± 12.1 years) were studied. All patients had arterial hypertension. Most of them (96.9%) had grade 3 hypertension according to ESH/ESC Guidelines for the management of arterial hypertension, 2018. Forty-two (43.1%) patients had coronary artery disease, 35 (35.4%) - atrial fibrillation (AF). The exclusion criteria was the presence of chronic obstructive pulmonary disease or other diseases associated with pulmonary hypertension. Patients were categorized according to National Institutes of Health Stroke Scale (NIHSS) severity in mild NIHSS (≤8) - 54 (55.1%) patients, moderate NIHSS (9–15) - 23 (23.5%) patients, and severe stroke NIHSS (≥16) - 21 (21.4%) patients. Median NIHSS score was 11.2 ± 1.7. All patients underwent a transthoracic echocardiography. A comparative assessment of echocardiographic parameters was performed in patients of lower (NIHSS score ≤ 4.5) and upper (NIHSS score≥14.5) quartile according to the NIHSS score.

Results

Linear regression analysis revealed that stroke severity was significantly correlated with right atrium end-diastolic volume (EDV) (r = 0.48, p &lt; 0.0001), right ventricular EDV (r = 0.62, p &lt; 0.0001), left atrium EDV (r = 0.41, p = 0.002), left ventricular ejection fraction (LVEF) (r = 0.4, p = 0.003) and pulmonary artery systolic pressure (PASP) (r = 0.89, p &lt; 0.0001). A multiple regression analysis showed that stroke severity was independently correlated with PASP (β=0.471, р=0.01), left atrium EDV (β=0.961, р=0.02) and LVEF (β=0.931, р=0.005) in patients with arterial hypertension and ischemic stroke.

In the group of patients with the upper quartile of NIHSS score, the right atrium EDV (64.7 ± 21.1 mm versus 47.6 ± 25.2 mm, р=0.04) and PASP (25.8 ± 9.3 mm versus 20.8 ± 8.0 mm, р=0.045) were higher. The left atrium EDV was higher in patients with LVEF below 50% ( 73.3 ± 36.9 mm vs 49.9 ± 18.5 mm, р=0.02) and in patients with AF (55.3 ± 19.8 vs 36.4 ± 14.6 mm, p &lt; 0.0001). At the same time PASP did not depend on the LVEF (22.1 ± 10.7 mm vs 21.6 ± 8.1 mm, р=0.9) and the presence of AF (21.9 ± 9.0 mm vs 21.7 ± 8.1 mm, р=0.9).

Conclusions

In patients with arterial hypertension the severity of acute ischemic stroke is associated with increases in right atrium end-diastolic volume and in pulmonary artery systolic pressure. An increase in pulmonary artery systolic pressure in patients with arterial hypertension and ischemic stroke does not depend on the left ventricular ejection fraction and atrial fibrillation.

Tuning the Geometric and Electronic Structure of Synthetic High-Valent Heme Iron(IV)-Oxo Models in the Presence of a Lewis Acid and Various Axial Ligands

High-valent ferryl species (e.g., (Por)Fe^IV═O, Cmpd-II) are observed or proposed key oxidizing intermediates in the catalytic cycles of heme-containing enzymes (P-450s, peroxidases, catalases, and cytochrome c oxidase) involved in biological respiration and oxidative metabolism. Herein, various axially ligated iron(IV)-oxo complexes were prepared to examine the influence of the identity of the base. These were generated by addition of various axial ligands (1,5-dicyclohexylimidazole (DCHIm), a tethered-imidazole system, and sodium derivatives of 3,5-dimethoxyphenolate and imidazolate). Characterization was carried out via UV-vis, electron paramagnetic resonance (EPR), ⁵⁷Fe Mössbauer, Fe X-ray absorption (XAS), and ^54/57Fe resonance Raman (rR) spectroscopies to confirm their formation and compare the axial ligand perturbation on the electronic and geometric structures of these heme iron(IV)-oxo species. Mössbauer studies confirmed that the axially ligated derivatives were iron(IV) and six-coordinate complexes. XAS and ^54/57Fe rR data correlated with slight elongation of the iron-oxo bond with increasing donation from the axial ligands. The first reported synthetic H-bonded iron(IV)-oxo heme systems were made in the presence of the protic Lewis acid, 2,6-lutidinium triflate (LutH⁺), with (or without) DCHIm. Mössbauer, rR, and XAS spectroscopic data indicated the formation of molecular Lewis acid ferryl adducts (rather than full protonation). The reduction potentials of these novel Lewis acid adducts were bracketed through addition of outer-sphere reductants. The oxidizing capabilities of the ferryl species with or without Lewis acid vary drastically; addition of LutH⁺ to F₈Cmpd-II (F₈ = tetrakis(2,6-difluorophenyl)porphyrinate) increased its reduction potential by more than 890 mV, experimentally confirming that H-bonding interactions can increase the reactivity of ferryl species.

Site-specific gene expression analysis from archived human intestine samples combining laser-capture microdissection and multiplexed color-coded probes

BACKGROUND

Alterations of site-specific gene expression profiles in disease-relevant networks within the different layers of the intestinal wall may contribute to the onset and clinical course of gastrointestinal disorders. To date, no systematic analysis has assessed and compared sub-regional gene expression patterns in all distinct layers of the gut using fresh frozen human samples. Our aim was to establish an optimized protocol for site-specific RNA isolation in order to achieve maximum RNA quality and amount for subsequent gene expression analysis combining laser-capture microdissection (LCM) with a probe-based technology, the NanoString nCounter Analysis system.

METHODS

Four full-thickness colon samples from patients who underwent surgery due to pathological conditions were processed and separated into epithelium, lamina propria, myenteric plexus, submucosa, and tunica muscularis by LCM. Site-specific marker expression by nCounter technology was performed on total RNA from each sub-region, respectively.

KEY RESULTS

Collecting ~10 mm² (~100 000-250 000 cells) of tissue from the epithelial layer, lamina propria, and myenteric plexus provided sufficient amounts of RNA of appropriate quality for subsequent analyses. In contrast, ~40 mm² (~250 000-650 000 cells) of tissue were dissected from the less cell-rich submucosal and tunica muscularis layer. nCounter analysis revealed a site-specific expression pattern of marker genes in the different layers of the colonic wall which were highly correlating (r > .9).

CONCLUSIONS AND INFERENCES

LCM in combination with nCounter expression analysis enables site-specific, sensitive, reliable detection, and quantification of mRNA from histologically heterogeneous tissues.

Lamin B1 regulates somatic mutations and progression of B-cell malignancies

Somatic hypermutation (SHM) is a pivotal process in adaptive immunity that occurs in the germinal centre and allows B cells to change their primary DNA sequence and diversify their antigen receptors. Here, we report that genome binding of Lamin B1, a component of the nuclear envelope involved in epigenetic chromatin regulation, is reduced during B-cell activation and formation of lymphoid germinal centres. Chromatin immunoprecipitation-Seq analysis showed that kappa and heavy variable immunoglobulin domains were released from the Lamin B1 suppressive environment when SHM was induced in B cells. RNA interference-mediated reduction of Lamin B1 resulted in spontaneous SHM as well as kappa-light chain aberrant surface expression. Finally, Lamin B1 expression level correlated with progression-free and overall survival in chronic lymphocytic leukaemia, and was strongly involved in the transformation of follicular lymphoma. In summary, here we report that Lamin B1 is a negative epigenetic regulator of SHM in normal B-cells and a 'mutational gatekeeper', suppressing the aberrant mutations that drive lymphoid malignancy.

Chemical and Morphological Inhomogeneity of Aluminum Metal and Oxides from Soft X-ray Spectromicroscopy

Oxygen and aluminum K-edge X-ray absorption spectroscopy (XAS), imaging from a scanning transmission X-ray microscope (STXM), and first-principles calculations were used to probe the composition and morphology of bulk aluminum metal, α- and γ-Al₂O₃, and several types of aluminum nanoparticles. The imaging results agreed with earlier transmission electron microscopy studies that showed a 2 to 5 nm thick layer of Al₂O₃ on all the Al surfaces. Spectral interpretations were guided by examination of the calculated transition energies, which agreed well with the spectroscopic measurements. Features observed in the experimental O and Al K-edge XAS were used to determine the chemical structure and phase of the Al₂O₃ on the aluminum surfaces. For unprotected 18 and 100 nm Al nanoparticles, this analysis revealed an oxide layer that was similar to γ-Al₂O₃ and comprised of both tetrahedral and octahedral Al coordination sites. For oleic acid-protected Al nanoparticles, only tetrahedral Al oxide coordination sites were observed. The results were correlated to trends in the reactivity of the different materials, which suggests that the structures of different Al₂O₃ layers have an important role in the accessibility of the underlying Al metal toward further oxidation. Combined, the Al K-edge XAS and STXM results provided detailed chemical information that was not obtained from powder X-ray diffraction or imaging from a transmission electron microscope.

Attosecond physics at the nanoscale

Recently two emerging areas of research, attosecond and nanoscale physics, have started to come together. Attosecond physics deals with phenomena occurring when ultrashort laser pulses, with duration on the femto- and sub-femtosecond time scales, interact with atoms, molecules or solids. The laser-induced electron dynamics occurs natively on a timescale down to a few hundred or even tens of attoseconds (1 attosecond  =  1 as  =  10^-18 s), which is comparable with the optical field. For comparison, the revolution of an electron on a 1s orbital of a hydrogen atom is  ∼152 as. On the other hand, the second branch involves the manipulation and engineering of mesoscopic systems, such as solids, metals and dielectrics, with nanometric precision. Although nano-engineering is a vast and well-established research field on its own, the merger with intense laser physics is relatively recent. In this report on progress we present a comprehensive experimental and theoretical overview of physics that takes place when short and intense laser pulses interact with nanosystems, such as metallic and dielectric nanostructures. In particular we elucidate how the spatially inhomogeneous laser induced fields at a nanometer scale modify the laser-driven electron dynamics. Consequently, this has important impact on pivotal processes such as above-threshold ionization and high-order harmonic generation. The deep understanding of the coupled dynamics between these spatially inhomogeneous fields and matter configures a promising way to new avenues of research and applications. Thanks to the maturity that attosecond physics has reached, together with the tremendous advance in material engineering and manipulation techniques, the age of atto-nanophysics has begun, but it is in the initial stage. We present thus some of the open questions, challenges and prospects for experimental confirmation of theoretical predictions, as well as experiments aimed at characterizing the induced fields and the unique electron dynamics initiated by them with high temporal and spatial resolution.

Synthesis of (18) F-Difluoromethylarenes from Aryl (Pseudo) Halides

A general method for the synthesis of [(18) F]difluoromethylarenes from [(18) F]fluoride for radiopharmaceutical discovery is reported. The method is practical, operationally simple, tolerates a wide scope of functional groups, and enables the labeling of a variety of arenes and heteroarenes with radiochemical yields (RCYs, not decay-corrected) from 10 to 60 %. The (18) F-fluorination precursors are readily prepared from aryl chlorides, bromides, iodides, and triflates. Seven (18) F-difluoromethylarene drug analogues and radiopharmaceuticals including Claritin, fluoxetine (Prozac), and [(18) F]DAA1106 were synthesized to show the potential of the method for applications in PET radiopharmaceutical design.

Transfer characteristics of subretinal visual implants: corneally recorded implant responses

PURPOSE

The subretinal Alpha IMS visual implant is a CE-approved medical device for restoration of visual functions in blind patients with end-stage outer retina degeneration. We present a method to test the function of the implant objectively in vivo using standard electroretinographic equipment and to assess the devices' parameter range for an optimal perception.

METHODS

Subretinal implant Alpha IMS (Retina Implant AG, Reutlingen, Germany) consists of 1500 photodiode-amplifier-electrode units and is implanted surgically into the subretinal space in blind retinitis pigmentosa patients. The voltages that regulate the amplifiers' sensitivity (V _gl) and gain (V _bias), related to the perception of contrast and brightness, respectively, are adjusted manually on a handheld power supply device. Corneally recorded implant responses (CRIR) to full-field illumination with long duration flashes in various implant settings for brightness gain (V _bias) and amplifiers' sensitivity (V _gl) are measured using electroretinographic setup with a Ganzfeld bowl in a protocol of increasing stimulus luminances up to 1000 cd/m².

RESULTS

CRIRs are a meaningful tool for assessing the transfer characteristic curves of the electronic implant in vivo monitoring the implants' voltage output as a function of log luminance in a sigmoidal shape. Changing the amplifiers' sensitivity (V _gl) shifts the curve left or right along the log luminance axis. Adjustment of the gain (V _bias) changes the maximal output. Contrast perception is only possible within the luminance range of the increasing slope of the function.

CONCLUSIONS

The technical function of subretinal visual implants can be measured objectively using a standard electroretinographic setup. CRIRs help the patient to optimise the perception by adjusting the gain and luminance range of the device and are a useful tool for clinicians to objectively assess the function of subretinal visual implants in vivo.