Microsecond time-resolved X-ray scattering by utilizing MHz repetition rate at second-generation XFELs.

Detecting microsecond structural perturbations in biomolecules has wide relevance in biology, chemistry and medicine. Here we show how MHz repetition rates at X-ray free-electron lasers can be used to produce microsecond time-series of protein scattering with exceptionally low noise levels of 0.001%. We demonstrate the approach by examining Jɑ helix unfolding of a light-oxygen-voltage photosensory domain. This time-resolved acquisition strategy is easy to implement and widely applicable for direct observation of structural dynamics of many biochemical processes.

Aqueous Ammonium Nitrate Investigated Using Photoelectron Spectroscopy of Cylindrical and Flat Liquid Jets.

Ammonium nitrate in aqueous solution was investigated with synchrotron radiation based photoelectron spectroscopy using two types of liquid jet nozzles. Electron emission from a cylindrical microjet of aqueous ammonium nitrate solution was measured at two different angles relative to the horizontal polarization of the incident synchrotron radiation, 90° and 54.7° (the "magic angle"), for a range of photon energies (470-530 eV). We obtained ß parameter values as a function of photon energy, based on a normalization procedure relying on simulations of background intensity with the SESSA (Simulation of Electron Spectra for Surface Analysis) package. The ß values are similar to literature data for O 1s ionization of liquid water, and the ß value of N 1s from NH4+ is higher than that for NO3-, by ≈0.1. The measurements also show that the photoelectron signal from NO3- exhibits a photon energy dependent cross section variation not observed in NH4+. Additional measurements using a flat jet nozzle found that the ammonium and nitrate peak area ratio was unaffected by changes in the takeoff angle, indicating a similar distribution of both ammonium and nitrate in the surface region.

Age affects drug survival rates of interleukin (IL)-17 and IL-23 inhibitors in patients with plaque psoriasis: Results from a retrospective, multicentric, multi-country, cohort study.

BACKGROUND: Scarce data related to the drug survival of biologic agents in psoriasis patients aged ≥65 years is available. OBJECTIVES: To evaluate the drug survival of interleukin (IL)-23 or the IL-17 inhibitors approved for the treatment of moderate-to-severe psoriasis in elderly patients (aged ≥65 years), compared with younger adult patients (aged <65 years), and to identify clinical predictors that can influence the drug survival. METHODS: This retrospective multicentric cohort study included adult patients with moderate-to-severe psoriasis, dissecting two-patient subcohorts based on age: elderly versus younger adults. Kaplan-Meier estimator and proportional hazard Cox regression models were used for drug survival analysis. RESULTS: We included 4178 patients and 4866 treatment courses; 934 were elderly (1072 treatment courses), and 3244 were younger patients (3794 treatment courses). Drug survival, considering all causes of interruption, was higher in patients aged <65 years than in elderly patients overall (log-rank p < 0.006). This difference was significant for treatment courses involving IL-23 inhibitors (p < 0.001) but not for those with IL-17 inhibitors (p = 0.2). According to both uni- and multi-variable models, elder age was associated with an increased risk of treatment discontinuation (univariable analysis: HR: 1.229, 95% CI 1.062-1.422; p < 0.006; multivariable analysis: HR: 1.199, 95% CI 1.010-1.422; p = 0.0377). Anti-IL-23 agents were associated with a reduced likelihood of treatment discontinuation after adjusting for other variables (HR: 0.520, 95% CI 0.368-0.735; p < 0.001). Being previously treated with IL-17 inhibitors increased the probability of discontinuation. CONCLUSION: Elderly patients with psoriasis have an increased risk of biologic treatment discontinuation compared with younger adult patients, particularly, if being treated with IL-23 inhibitors. However, in stratified analyses conducted in elderly patients, IL-23 inhibitors showed higher drug survival rates than IL-17 inhibitors.

Kilohertz droplet-on-demand serial femtosecond crystallography at the European XFEL station FXE.

X-ray Free Electron Lasers (XFELs) allow the collection of high-quality serial femtosecond crystallography data. The next generation of megahertz superconducting FELs promises to drastically reduce data collection times, enabling the capture of more structures with higher signal-to-noise ratios and facilitating more complex experiments. Currently, gas dynamic virtual nozzles (GDVNs) stand as the sole delivery method capable of best utilizing the repetition rate of megahertz sources for crystallography. However, their substantial sample consumption renders their use impractical for many protein targets in serial crystallography experiments. Here, we present a novel application of a droplet-on-demand injection method, which allowed operation at 47 kHz at the European XFEL (EuXFEL) by tailoring a multi-droplet injection scheme for each macro-pulse. We demonstrate a collection rate of 150 000 indexed patterns per hour. We show that the performance and effective data collection rate are comparable to GDVN, with a sample consumption reduction of two orders of magnitude. We present lysozyme crystallographic data using the Large Pixel Detector at the femtosecond x-ray experiment endstation. Significant improvement of the crystallographic statistics was made by correcting for a systematic drift of the photon energy in the EuXFEL macro-pulse train, which was characterized from indexing the individual frames in the pulse train. This is the highest resolution protein structure collected and reported at the EuXFEL at 1.38 Å resolution.

Structure of the Lysinibacillus sphaericus Tpp49Aa1 pesticidal protein elucidated from natural crystals using MHz-SFX.

The Lysinibacillus sphaericus proteins Tpp49Aa1 and Cry48Aa1 can together act as a toxin toward the mosquito Culex quinquefasciatus and have potential use in biocontrol. Given that proteins with sequence homology to the individual proteins can have activity alone against other insect species, the structure of Tpp49Aa1 was solved in order to understand this protein more fully and inform the design of improved biopesticides. Tpp49Aa1 is naturally expressed as a crystalline inclusion within the host bacterium, and MHz serial femtosecond crystallography using the novel nanofocus option at an X-ray free electron laser allowed rapid and high-quality data collection to determine the structure of Tpp49Aa1 at 1.62 Å resolution. This revealed the packing of Tpp49Aa1 within these natural nanocrystals as a homodimer with a large intermolecular interface. Complementary experiments conducted at varied pH also enabled investigation of the early structural events leading up to the dissolution of natural Tpp49Aa1 crystals-a crucial step in its mechanism of action. To better understand the cooperation between the two proteins, assays were performed on a range of different mosquito cell lines using both individual proteins and mixtures of the two. Finally, bioassays demonstrated Tpp49Aa1/Cry48Aa1 susceptibility of Anopheles stephensi, Aedes albopictus, and Culex tarsalis larvae-substantially increasing the potential use of this binary toxin in mosquito control.

Form factor determination of biological molecules with X-ray free electron laser small-angle scattering (XFEL-SAS).

Free-electron lasers (FEL) are revolutionizing X-ray-based structural biology methods. While protein crystallography is already routinely performed at FELs, Small Angle X-ray Scattering (SAXS) studies of biological macromolecules are not as prevalent. SAXS allows the study of the shape and overall structure of proteins and nucleic acids in solution, in a quasi-native environment. In solution, chemical and biophysical parameters that have an influence on the structure and dynamics of molecules can be varied and their effect on conformational changes can be monitored in time-resolved XFEL and SAXS experiments. We report here the collection of scattering form factors of proteins in solution using FEL X-rays. The form factors correspond to the scattering signal of the protein ensemble alone; the scattering contributions from the solvent and the instrument are separately measured and accurately subtracted. The experiment was done using a liquid jet for sample delivery. These results pave the way for time-resolved studies and measurements from dilute samples, capitalizing on the intense and short FEL X-ray pulses.

3D-printed sheet jet for stable megahertz liquid sample delivery at X-ray free-electron lasers.

X-ray free-electron lasers (XFELs) can probe chemical and biological reactions as they unfold with unprecedented spatial and temporal resolution. A principal challenge in this pursuit involves the delivery of samples to the X-ray interaction point in such a way that produces data of the highest possible quality and with maximal efficiency. This is hampered by intrinsic constraints posed by the light source and operation within a beamline environment. For liquid samples, the solution typically involves some form of high-speed liquid jet, capable of keeping up with the rate of X-ray pulses. However, conventional jets are not ideal because of radiation-induced explosions of the jet, as well as their cylindrical geometry combined with the X-ray pointing instability of many beamlines which causes the interaction volume to differ for every pulse. This complicates data analysis and contributes to measurement errors. An alternative geometry is a liquid sheet jet which, with its constant thickness over large areas, eliminates the problems related to X-ray pointing. Since liquid sheets can be made very thin, the radiation-induced explosion is reduced, boosting their stability. These are especially attractive for experiments which benefit from small interaction volumes such as fluctuation X-ray scattering and several types of spectroscopy. Although their use has increased for soft X-ray applications in recent years, there has not yet been wide-scale adoption at XFELs. Here, gas-accelerated liquid sheet jet sample injection is demonstrated at the European XFEL SPB/SFX nano focus beamline. Its performance relative to a conventional liquid jet is evaluated and superior performance across several key factors has been found. This includes a thickness profile ranging from hundreds of nanometres to 60 nm, a fourfold increase in background stability and favorable radiation-induced explosion dynamics at high repetition rates up to 1.13 MHz. Its minute thickness also suggests that ultrafast single-particle solution scattering is a possibility.

Mix-and-extrude: high-viscosity sample injection towards time-resolved protein crystallography.

Time-resolved crystallography enables the visualization of protein molecular motion during a reaction. Although light is often used to initiate reactions in time-resolved crystallography, only a small number of proteins can be activated by light. However, many biological reactions can be triggered by the interaction between proteins and ligands. The sample delivery method presented here uses a mix-and-extrude approach based on 3D-printed microchannels in conjunction with a micronozzle. The diffusive mixing enables the study of the dynamics of samples in viscous media. The device design allows mixing of the ligands and protein crystals in 2 to 20 s. The device characterization using a model system (fluorescence quenching of iq-mEmerald proteins by copper ions) demonstrated that ligand and protein crystals, each within lipidic cubic phase, can be mixed efficiently. The potential of this approach for time-resolved membrane protein crystallography to support the development of new drugs is discussed.

XFEL Microcrystallography of Self-Assembling Silver n-Alkanethiolates.

New synthetic hybrid materials and their increasing complexity have placed growing demands on crystal growth for single-crystal X-ray diffraction analysis. Unfortunately, not all chemical systems are conducive to the isolation of single crystals for traditional characterization. Here, small-molecule serial femtosecond crystallography (smSFX) at atomic resolution (0.833 Å) is employed to characterize microcrystalline silver n-alkanethiolates with various alkyl chain lengths at X-ray free electron laser facilities, resolving long-standing controversies regarding the atomic connectivity and odd-even effects of layer stacking. smSFX provides high-quality crystal structures directly from the powder of the true unknowns, a capability that is particularly useful for systems having notoriously small or defective crystals. We present crystal structures of silver n-butanethiolate (C4), silver n-hexanethiolate (C6), and silver n-nonanethiolate (C9). We show that an odd-even effect originates from the orientation of the terminal methyl group and its role in packing efficiency. We also propose a secondary odd-even effect involving multiple mosaic blocks in the crystals containing even-numbered chains, identified by selected-area electron diffraction measurements. We conclude with a discussion of the merits of the synthetic preparation for the preparation of microdiffraction specimens and compare the long-range order in these crystals to that of self-assembled monolayers.

Drug Survival of Interleukin (IL)­17 and IL­23 Inhibitors for the Treatment of Psoriasis: A Retrospective Multi­country, Multicentric Cohort Study.

BACKGROUND: Drug survival, defined as the length of time from initiation to discontinuation of a given therapy, allows comparisons between drugs, helps to predict patient's likelihood of remaining on a specific treatment, and achieving the best decision for each patient in daily clinical practice. OBJECTIVE: The aim of this study was to provide data on drug survival of secukinumab, ixekizumab, brodalumab, guselkumab, tildrakizumab, and risankizumab in a large international cohort, and to identify clinical predictors that might have an impact on the drug survival of these drugs. METHODS: This was a retrospective, multicentric, multi-country study that provides data of adult patients with moderate to severe psoriasis who started treatment with an interleukin (IL)-17 or IL-23 inhibitor between 1 February 2015 and 31 October 2021. Data were collected from 19 distinct hospital and non-hospital-based dermatology centers from Canada, Czech Republic, Italy, Greece, Portugal, Spain, and Switzerland. Kaplan-Meier estimator and proportional hazard Cox regression models were used for drug survival analysis. RESULTS: A total of 4866 treatment courses (4178 patients)-overall time of exposure of 9500 patient-years-were included in this study, with 3164 corresponding to an IL-17 inhibitor (secukinumab, ixekizumab, brodalumab) and 1702 corresponding to an IL-23 inhibitor (guselkumab, risankizumab, tildrakizumab). IL-23 inhibitors had the highest drug survival rates during the entire study period. After 24 months of treatment, the cumulative probabilities of drug survival were 0.92 (95% confidence interval [CI] 0.89-0.95) for risankizumab, 0.90 (95% CI 0.88-0.92) for guselkumab, 0.80 (95% CI 0.76-0.84) for brodalumab, 0.79 (95% CI 0.76-0.82) for ixekizumab, and 0.75 (95% CI 0.73-0.77) for secukinumab. At 36 months, only guselkumab [0.88 (95% CI 0.85-0.91)], ixekizumab [0.73 (95% CI 0.70-0.76)], and secukinumab [0.67 (95% CI 0.65-0.70)] had more than 40 patients at risk of drug discontinuation. Only two drugs had more than 40 patients at risk of drug discontinuation at 48 months, with ixekizumab demonstrating to have a higher cumulative probability of drug survival [0.71 (95% CI 0.68-0.75)] when compared with secukinumab [0.63 (95% CI 0.60-0.66)]. Secondary failure was the main cause for drug discontinuation. According to the final multivariable model, patients receiving risankizumab, guselkumab, and ixekizumab were significantly less likely to discontinue treatment than those receiving secukinumab. Previous exposure to biologic agents, absent family history of psoriasis, higher baseline body mass index (BMI), and higher baseline Psoriasis Area and Severity Index (PASI) were identified as predictors of drug discontinuation. CONCLUSION: The cumulative probability of drug survival of both IL-17 and IL-23 inhibitors was higher than 75% at 24 months, with risankizumab and guselkumab demonstrating to have overall cumulative probabilities ≥ 90%. Biological agent chosen, prior exposure to biologic agents, higher baseline BMI and PASI values, and absence of family history of psoriasis were identified as predictors for drug discontinuation. Risankizumab, guselkumab, and ixekizumab were less likely to be discontinued than secukinumab.

3D printed devices and infrastructure for liquid sample delivery at the European XFEL.

The Sample Environment and Characterization (SEC) group of the European X-ray Free-Electron Laser (EuXFEL) develops sample delivery systems for the various scientific instruments, including systems for the injection of liquid samples that enable serial femtosecond X-ray crystallography (SFX) and single-particle imaging (SPI) experiments, among others. For rapid prototyping of various device types and materials, sub-micrometre precision 3D printers are used to address the specific experimental conditions of SFX and SPI by providing a large number of devices with reliable performance. This work presents the current pool of 3D printed liquid sample delivery devices, based on the two-photon polymerization (2PP) technique. These devices encompass gas dynamic virtual nozzles (GDVNs), mixing-GDVNs, high-viscosity extruders (HVEs) and electrospray conical capillary tips (CCTs) with highly reproducible geometric features that are suitable for time-resolved SFX and SPI experiments at XFEL facilities. Liquid sample injection setups and infrastructure on the Single Particles, Clusters, and Biomolecules and Serial Femtosecond Crystallography (SPB/SFX) instrument are described, this being the instrument which is designated for biological structure determination at the EuXFEL.

Secukinumab demonstrates improvements in absolute and relative psoriasis area severity indices in moderate-to-severe plaque psoriasis: results from a European, multicentric, retrospective, real-world study.

Objective: This European, multicentric, retrospective study aimed to collect data on secukinumab effectiveness in a real-world setting.Research design and methods: All psoriatic patients starting secukinumab between January 2016 and February 2017 in 11 European centers were followed until February 2018 and retrospectively evaluated.Main outcome measures: Secukinumab effectiveness was assessed by relative improvement from baseline of the Psoriasis Area Severity Index (PASI) and absolute PASI score modifications throughout 52 weeks of therapy. Additionally measures assessing effectiveness were used, including improvements of body surface area (BSA) and Dermatology Life Quality Index (DLQI).Results: Out of the 330 patients with potentially 52-week treatment duration, naïve to biologics patients showed greater probability to achieve PASI score of ≤1, ≤2, ≤3, and ≤5 at week 12, compared to bio-experienced patients (45.86% vs. 27.17%, 62.42% vs. 42.42%, 73.89% vs. 57.80%, and 84.08% vs. 74.57%, respectively). The greater effectiveness of secukinumab treatment in bio-naïve patients was confirmed at week 24 and 52.Conclusions: In this real-world experience, secukinumab was proven effective in treating psoriasis patients throughout a 52-weeks observation period, with higher response in bio-naïve patients. This study may contribute to defining the clinical profile of secukinumab best-responders.

Dynamics of soft nanoparticle suspensions at hard X-ray FEL sources below the radiation-damage threshold.

The application of X-ray photon correlation spectroscopy (XPCS) at free-electron laser (FEL) facilities enables, for the first time, the study of dynamics on a (sub-)nanometre scale in an unreached time range between femtoseconds and seconds. For soft-matter materials, radiation damage is a major limitation when going beyond single-shot applications. Here, an XPCS study is presented at a hard X-ray FEL on radiation-sensitive polymeric poly(N-isopropylacrylamide) (PNIPAM) nanoparticles. The dynamics of aqueous suspensions of densely packed silica-PNIPAM core-shell particles and a PNIPAM nanogel below the radiation-damage threshold are determined. The XPCS data indicate non-diffusive behaviour, suggesting ballistic and stress-dominated heterogeneous particle motions. These results demonstrate the feasibility of XPCS experiments on radiation-sensitive soft-matter materials at FEL sources and pave the way for future applications at MHz repetition rates as well as ultrafast modes using split-pulse devices.

X-ray spectroscopy with variable line spacing based on reflection zone plate optics.

X-ray spectroscopy is a method, ideally suited for investigating the electronic structure of matter, which has been enabled by the rapid developments in light sources and instruments. The x-ray fluorescence lines of life-relevant elements such as carbon, nitrogen, and oxygen are located in the soft x-ray regime and call for suitable spectrometer devices. In this Letter, we present a high-resolution spectrum of liquid water, recorded with a soft x-ray spectrometer based on a reflection zone plate (RZP) design. The RZP-based spectrometer with meridional variation of line space density from 2953 to 3757 l/mm offers extremely high detection efficiency and, at the same time, medium energy resolution. We can reproduce the well-known splitting of liquid water in the lone pair regime with 10 s acquisition time.

Kinetics and thermodynamics of chlorpromazine interaction with lipid bilayers: effect of charge and cholesterol.

Passive transport across cell membranes is the major route for the permeation of xenobiotics through tight endothelia such as the blood­brain barrier. The rate of passive permeation through lipid bilayers for a given drug is therefore a critical step in the prediction of its pharmacodynamics. We describe a detailed study on the kinetics and thermodynamics for the interaction of chlorpromazine (CPZ), an antipsychotic drug used in the treatment of schizophrenia, with neutral and negatively charged lipid bilayers. Isothermal titration calorimetry was used to study the partition and translocation of CPZ in lipid membranes composed of pure POPC, POPC:POPS (9:1), and POPC:Chol:POPS (6:3:1). The membrane charge due to the presence of POPS as well as the additional charge resulting from the introduction of CPZ in the membrane were taken into account, allowing the calculation of the intrinsic partition coefficients (K(P)) and the enthalpy change (ΔH) associated with the process. The enthalpy change upon partition to all lipid bilayers studied is negative, but a significant entropy contribution was also observed for partition to the neutral membrane. Because of the positive charge of CPZ, the presence of negatively charged lipids in the bilayer increases both the observed amount of CPZ that partitions to the membrane (KP(obs)) and the magnitude of ΔH. However, when the electrostatic effects are discounted, the intrinsic partition coefficient was smaller, indicating that the hydrophobic contribution was less significant for the negatively charged membrane. The presence of cholesterol strongly decreases the affinity of CPZ for the bilayer in terms of both the amount of CPZ that associates with the membrane and the interaction enthalpy. A quantitative characterization of the rate of CPZ translocation through membranes composed of pure POPC and POPC:POPS (9:1) was also performed using an innovative methodology developed in this work based on the kinetics of the heat evolved due to the interaction of CPZ with the membranes.

Temperature effect on the bilayer stacking in multilamellar lipid vesicles.

The small-angle region of the Bragg diffraction of MLV samples is a simple and powerful tool for the study of mesoscopic lipid structures either alone or in interaction with molecules of biological interest. It is also a helpful tool to obtain the much needed thermotropic phase diagrams of lipid mixtures. In the course of our work, we found that the analysis of the diffractograms obtained as a function of temperature is not as straightforward as we expected. When the aqueous medium is concentrated in univalent salts, the small-angle X-ray scattering, SAXS, develops several peaks that have been interpreted to result from regions with different thickness of the interbilayer region. However, a systematic study shows that nonzero ionic strength is by no means a necessary criterion for irregularity of bilayer stacking. We show that MLV in water are uniform and stable if made, kept, and measured at the same temperature. If not, the lamellar repeat distance is smaller than the equilibrated one, eventually developing transient multimodal SAXS diffractions. We present a detailed study of this phenomenon using SAXS and dynamic light scattering and conclude that the deviations from the equilibrium interbilayer distance is a consequence of geometric constraints created by the insufficient thermal expansion of the lipid bilayers.

The thermotropism and prototropism of ternary mixtures of ceramide C16, cholesterol and palmitic acid. An exploratory study.

Mixtures of ceramides with other lipids in the presence of water are key components of the structure of the lipid matrix of the stratum corneum and are involved in lateral phase separation processes occurring in lipid membranes. Besides their structural role, ceramides are functional for cell signaling and trafficking. We elected, as our object of study, a mixture of N-hexadecanoylceroyl-d-erythro-sphyngosine, C16-Cer, with cholesterol, Ch, in a molar proportion 54:46 in excess water to which palmitic acid, PA, is added in varying amounts. The chosen C16-Cer:Ch proportion replicates the relative abundance of ceramides and cholesterol found in the stratum corneum lipid matrix. For each lipidic composition, we identify the phases in equilibrium and study the thermotropism of the system, using differential scanning calorimetry and temperature-dependent small and wide-angle X-ray powder diffraction. Since the molecular aggregation of the system and its mesoscopic properties are affected by the degree of protonation of the PA, we explore mixtures with several PA contents at two extreme pH values, 9.0 and 4.0. A specific C16-Cer:Ch:PA composition forms at pH 9.0 a lamellar crystalline aggregate, to which we attribute the stoichiometry C16-Cer(5)Ch(4)PA(2), that melts at 88-90 °C to give a H(II) phase. For pH values at which there is partial or total protonation of PA another L(C) C16-Cer:Ch (2:3) stoichiometric aggregate is observed, identical to that previously reported for C16-Cer:Ch mixtures (Souza et al., 2009, J. Phys. Chem. B, 113, 1367-1375), coexisting with a lamellar fluid phase. For pH 4.0 and 7.0, the existing lamellar liquid crystalline converts into a isotropic fluid phase at high temperatures. It is also found that the miscibility of PA in the C16-Cer:Ch mixture at pH 4.0 does not exceed ca. 18 mol%, but for pH 9.0 no free PA is detected at least until 60 mol%.