Cloning and Overexpressing Membrane Proteins Using Pichia pastoris (Komagataella phaffii)

Understanding the structure and function of key proteins located within biological membranes is essential for fundamental knowledge and therapeutic applications. Robust cell systems allowing their actual overexpression are required, among which stands the methylotrophic yeast Pichia pastoris. This system proves highly efficient in producing many eukaryotic membrane proteins of various functions and structures at levels and quality compatible with their subsequent isolation and molecular investigation. This article describes a set of basic guidelines and directions to clone and select recombinant P. pastoris clones overexpressing eukaryotic membrane proteins. Illustrative results obtained for a panel of mammalian membrane proteins are presented, and hints are given on a series of experimental parameters that may substantially improve the amount and/or the functionality of the expressed proteins. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Designing and cloning a P. pastoris expression vector Basic Protocol 2: Integrative transformation of P. pastoris and selection of recombinant clones Basic Protocol 3: Culturing transformed P. pastoris for membrane protein expression Basic Protocol 4: Yeast cell lysis and membrane preparation Basic Protocol 5: Immunodetection of expressed membrane proteins: western blot Alternate Protocol 1: Immunodetection of expressed membrane proteins: dot blot Alternate Protocol 2: Immunodetection of expressed membrane proteins: yeastern blot Basic Protocol 6: Activity assay: ligand-binding analysis of an expressed GPCR.

Extending the Affinity Range of Weak Affinity Chromatography for the Identification of Weak Ligands Targeting Membrane Proteins

The identification of weak-affinity ligands targeting membrane proteins is of great interest in Fragment-Based Drug Design (FBDD). Recently, miniaturized weak affinity chromatography (WAC) has been proposed as a valuable tool to study interactions between small ligands and wild-type membrane proteins embedded in so-called nanodisc biomimetic membranes immobilized on GMA-co-EDMA monoliths in situ-synthesized in capillary columns (less than one microliter in volume). In this proof-of-concept study, the achievable affinity range was limited to medium affinity (low micromolar range). The present work investigates different strategies to extend the affinity range towards low affinities, either by increasing the density of membrane proteins on the chromatographic support or by reducing non-specific interactions with the monolith. The combination of the use of a new and more hydrophilic monolithic support (poly(DHPMA-co-MBA)) and a multilayer nanodisc grafting process (up to three layers) allows a significant increase in the membrane protein density by a more than three-fold factor (up to 5.4 pmol cm-1). Such an increase in protein density associated with reduced non-specific interactions makes it possible to extend the range of detectable affinity, as demonstrated by the identification and characterization of affinities of very low-affinity ligands (Kd values of several hundred micromolar) for the adenosine receptor AA2AR used as a model protein, which was not possible before. The affinity was confirmed by competition experiments.

Characterization of anti-GASP motif antibodies that inhibit the interaction between GPRASP1 and G protein-coupled receptors

G protein-coupled receptor associated sorting protein 1 (GPRASP1) belongs to a family of 10 proteins that display sequence homologies in their C-terminal region. Several members including GPRASP1 also display a short repeated sequence called the GASP motif that is critically involved in protein-protein interactions with G protein-coupled receptors (GPCRs). Here, we characterized anti-GASP motif antibodies and investigated their potential inhibitory functions. We first showed that our in-house anti-GPRASP1 rabbit polyclonal serum contains anti-GASP motif antibodies and purified them by affinity chromatography. We further showed that these antibodies can detect GPRASP1 and GPRASP2 in Western blot, immunoprecipitation and immunofluorescence experiments while a mutant of GPRASP2, in which the most conserved hydrophobic core of the GASP motifs is mutated, was no more detected. Further characterization of anti-GASP motif antibodies by ELISA and Surface Plasmon Resonance assays suggests that GASP motifs function as multivalent epitopes. Finally, we set-up an Amplified Luminescent Proximity Homogeneous AlphaScreen® assay to detect the interaction between purified ADRB2 receptor and the central domain of GPRASP1 and showed that anti-GASP motif antibodies efficiently inhibit this interaction. Altogether, our results suggest that anti-GASP motif antibodies could represent a valuable tool to neutralize the interaction of GPRASP1 and GPRASP2 with different GPCRs.

Very cold and ultra cold neutron sources for ESS

The goal of the “Workshop on Very Cold and Ultra Cold Neutron Sources for ESS” was to discuss scientific cases, ideas and possibilities for the implementation of sources of Very Cold and Ultra Cold neutrons at the European Spallation Source. The ESS facility, presently under construction, offers several possibilities for in-pile UCN or VCN sources, in primis thanks to the available space below the spallation target where additional neutron sources can be placed to complement those above the target. Neutron beams can be extracted over a wide angular range with a grid of forty-two beamports with 6° average angular separation, allowing future instruments to be installed which may view either the upper or lower moderator systems. Of greatest interest for fundamental physics is the so-called Large Beamport foreseen for the NNBAR experiment. This beamport is also particularly well suited to feed a UCN source, for which several ideas were presented that employ either superfluid helium or solid deuterium as established neutron converter materials. Concepts for VCN sources make use of novel materials for VCN production and/or advanced reflectors to increase yields in the coldest part of the neutron spectrum from a cryogenic neutron source. In this paper we discuss these ideas and the possible locations of UCN and VCN sources at ESS.

Significant improvement in blood pressure control among older adults with hypertension in rural South Africa: findings from a prospective 5,000-patient cohort, 2014–2019

Background

Sub-Saharan Africa is undergoing an epidemiologic transition dominated by a widespread epidemic of hypertension (HTN). Since 2014, we began studying a cohort of 5,059 individuals in rural South Africa, to describe the evolution of HTN among older adults, and understand the impact of targeted interventions by local health systems.

Purpose

Characterize the updated prevalence and incidence of HTN in a prospective cohort between baseline (2014) and follow-up (2019), and describe changes in blood pressure (BP) treatment.

Methods

HTN was defined as systolic blood pressure (SBP) ≥140 mm Hg, diastolic blood pressure (DBP) ≥90 mm Hg, or self-reported medication use. Prevalence and incidence rates were calculated using inverse-probability weights to account for mortality and attrition. Poisson regression was used to identify predictors of disease incidence. We calculated the percentage of individuals with controlled versus uncontrolled HTN (with 140/90 mm Hg as cutoff), self-reported medication use, and compared these values between 2014 and 2019.

Results

Compared to 2014 (n=5,059), study participants in 2019 (n=4,176) were expectedly older (mean age 61.7±13.1 vs 66.0±13.0 years) but had similar sex distribution (53.6% vs 53.5% females) and weighted rates of obesity (mean BMI 27.5±10.0 vs 27.0±6.5), with higher rates of smoking (9.1% vs 11.8%) and diabetes (11.1% vs 13.7%). The HTN prevalence did not increase over time (58.4% vs 59.8%), and there was a significant reduction in mean SBP (138.0 vs 128.5 mm Hg, p<0.001) and DBP (82.1 vs 79.6 mm Hg, p<0.001). In the subgroup of hypertensive individuals with measured BP and self-reported medication use in both 2014 and 2019 (n=796), the percentage who had controlled HTN on medications increased from 44.5% to 62.3% while the percentage who had uncontrolled HTN on medications or uncontrolled HTN not on medications decreased (48.5% to 32.2% and 7.2% to 3%, respectively) from 2014 to 2019 (Figure 1). The HTN incidence was 6.2 per 100 person-years, which was lower than prior reports from this area (8.4 per 100 person-years in 2010–2015); in multivariable models, age was the only significant predictor of incident HTN. In the subgroup of individuals who were healthy at baseline with measured BP and self-reported medication use in 2014 and 2019 (n=2,257), very few developed HTN by 2019 (15.2%); of those, the majority already had controlled HTN and was on medications by 2019 (Figure 2).

Conclusions

The prevalence of HTN did not increase in this aging cohort; in fact there was a clinically and statistically significant decline in mean BP and a substantial increase in the proportion of hypertensive patients with controlled HTN taking medications between 2014 and 2019. The prevalence of obesity, smoking and other risk factors did not decrease over time, suggesting that the mean BP decrease in this cohort is likely due to increased access and adherence to medications, promoted by local health systems.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute on Aging (P01 AG041710), and Department of Science and Innovation, the University of the Witwatersrand, South Africa.

Cryo-electron microscopy unveils unique structural features of the human Kir2.1 channel

We present the first structure of the human Kir2.1 channel containing both transmembrane domain (TMD) and cytoplasmic domain (CTD). Kir2.1 channels are strongly inward-rectifying potassium channels that play a key role in maintaining resting membrane potential. Their gating is modulated by phosphatidylinositol 4,5-bisphosphate (PIP₂). Genetically inherited defects in Kir2.1 channels are responsible for several rare human diseases, including Andersen's syndrome. The structural analysis (cryo-electron microscopy), surface plasmon resonance, and electrophysiological experiments revealed a well-connected network of interactions between the PIP₂-binding site and the G-loop through residues R312 and H221. In addition, molecular dynamics simulations and normal mode analysis showed the intrinsic tendency of the CTD to tether to the TMD and a movement of the secondary anionic binding site to the membrane even without PIP₂. Our results revealed structural features unique to human Kir2.1 and provided insights into the connection between G-loop and gating and the pathological mechanisms associated with this channel.

A-19 Distress Predicts Poorer Cognitive Performance At Post-Injury In Concussed Athletes

Purpose: This study evaluated the consistency between athletes’ self-reported cognitive symptoms and cognitive test performance. Methods: The sample included 784 Canadian Football League athletes who underwent standardized cognitive testing with cognitive testing (ImPACT) and the Brief Symptom Inventory (BSI-18) at baseline. Over 2 consecutive seasons, 46 players were diagnosed with concussions following assessment with team physicians within 48 hours; 10 were eliminated due to missing data. Five cognitive symptoms (feeling slowed down, feeling in a fog, not feeling right, difficulties concentration, difficulties with memory) were used to create a composite score (Cog). The Cog index, the depression, anxiety, total index scores from the BSI, and the 5 ImPACT cognitive domains were correlated at baseline and post-injury. History of learning disabilities, ADHD, psychiatric diagnosis, and history of concussion were co-variates. Results: There were no significant correlations between Cog, depression, anxiety or total BSI scores and the ImPACT cognitive domains at baseline. At post injury there were no significant correlations between Cog or ImPACT index scores. In contrast, significant negative correlations were found between BSI Anxiety and verbal memory (r = 0.67, p < 0.01), visual memory (r = 0.68, p < 0.01), and visual-motor processing speed (r = 0.48, p < 0.05). In addition, there were significant negative correlations between the BSI total score and visual memory (r = 0.51, p < 0.05) and reaction time (r = 0.55, p < 0.05). Conclusions: Self-reported cognitive difficulties do not correlate with poorer cognitive outcomes in our sample of professional football players. However, distress at post-injury was significantly correlated to performance, suggesting psychological variables may play a role in cognitive functioning.

A-37 Ocular Motor Impairments in Concussion Professional Football Players

Purpose: The purpose of this study was to examine baseline and post-concussion injury characteristics of ocular eye movements using the Sync Think visual eye tracking apparatus in professional football players in the Canadian Football League (CFL). Methods: The visual tracking testing protocol uses an integrated stimulus presentation-eye tracking apparatus (EyeLink CL; SR Research, Ontario, Canada) with which eye movements were recorded at 500 Hz using infrared video-oculography. The standard deviation of radial errors (SDRE) and tangential errors (SDTE) were used to determine poor visual tracking. Participants were (n = 748) rostered players in the Canadian Football League. All participants completed assessments at baseline. Sixteen players completed post-concussion assessments and 98 players completed post-exertional assessments during the 2021 season to evaluate the impact of physical exertion on ocular movement metrics. Results: Participants with diagnosed concussions (n = 16+) demonstrated significantly poorer performance on measures of both gaze stability and smooth pursuit (p < 0.001). The poorer results were correlated with significantly higher subjective ratings of dizziness (p < 0.01) and fogginess (p < 0.001). In contrast, healthy participants who completed the same ocular motor assessments demonstrated no significant differences compared to baseline test performance. Conclusions: Findings suggest that subtle differences in oculomotor functioning arise from sport concussion in professional football players. Further research with larger sample sizes and correlation with other cognitive and physical outcomes is warranted.

A-12 Mental Health Outcomes for CFL Athletes with ADHD

Purpose: Current research suggests that athletes with Attention Deficit Hyperactivity Disorder (ADHD) are at risk for poorer outcomes arising from sport related concussions (SRC). There is limited research related evaluating mental health outcomes in athletes diagnosed with ADHD. The purpose of the study is to evaluate mental health outcomes among Canadian Football League (CFL) athletes with (ADHD) and to measure outcomes based upon a history of concussion. Methods: Professional football players from the CFL (n = 784) were administered a baseline mental health measure, the Health-Related Quality of Life (HRQL), as a component of pre-season evaluations as part of a larger cohort study (Active Rehabilitation). Diagnosis of ADHD was the independent variable and HRQL index scores measuring physical functioning, depression, cognitive functioning, were dependent variables. A second analysis compared ADHD athletes with no history of concussion to those with a history of concussion on the HRQL indexes. Results: Participants diagnosed with ADHD (n = 80) had statistically significant differences on the Physical Functioning (t(782) = −3.359, p < 0.001), Depression ((t(782) = −2.820, p = 0.002) and Cognitive (t(782) = −3.570, p < 0.001) domains of the HRQL, compared to athletes without ADHD. Among the athletes who are diagnosed with ADHD, no mental health differences were found between those who have at least one concussion and those who do not. Conclusions: This study did not find a significant effect of concussion on mental health outcomes in participants with ADHD. However, athletes with ADHD present with higher mental health symptoms which may merit closer monitoring.

O-285 Artificial intelligence algorithms reach expert-level accuracy in automated grading of blastocyst morphology assessment based on static embryo images and Gardner criteria

Study question

Can artificial intelligence (AI) algorithms reach expert-level accuracy in blastocyst morphology assessment according to Gardner criteria?

Summary answer

The prediction accuracy of the best performing AI algorithm (Deit), outperformed human-level mean accuracies compared to an embryologist majority vote for all Gardner morphological criteria.

What is known already

Routinely, morphological grading of blastocysts is performed visually according to Gardner criteria, which suggest expansion (EXP), quality of inner cell mass (ICM), and trophectoderm (TE) as key parameters to predict treatment outcome. Consequently, blastocyst scoring is prone to inter-and intra-observer variability, which may lead to inconsistencies in selecting blastocysts for transfer. AI-based algorithms may help to improve treatment outcome predictability, as it has been suggested recently. In those studies, parameters such as blastocyst quality or stage were annotated by experts from static or time-lapse-derived blastocyst images, to train AI algorithms, e.g. XCeption or YOLO, and compare them to human annotators.

Study design, size, duration

This retrospective study involves 2,270 images from 837 patients collected over a period of four years in a university IVF clinic.

Participants/materials, setting, methods

All images were annotated by one senior embryologist and divided into a training and a balanced test set. Subsequently, eight embryologists labeled 300 test set images such that every single image was seen by at least four embryologists. Annotators diverging from the ensemble vote for more than one standard deviation were excluded (n = 2) to set the ground truth labels. Finally, three AI architectures (XCeption, Swin, Deit) were trained and evaluated on that particular ground truth.

Main results and the role of chance

Out of nine annotators, labelling accuracy of two embryologists diverged from the consensus vote for more than one standard deviation for at least one of the three Gardner criteria. The consensus vote was built from the remaining seven annotators (mean accuracy EXP 0.81, ICM 0.70, TE 0.67). The Swin architecture outperformed the mean expert accuracy for all three criteria (EXP 0.82, ICM 0.76, TE 0.68), while the Deit and the XCeption architecture outperformed the mean expert accuracy in ICM accuracy (Deit 0.72, XCeption 0.73), and performed equal or worse in EXP and TE accuracy (Deit EXP 0.77, ICM 0.73; XCeption EXP 0.77, TE 0.66). When compared to a recent study conducted on time-lapse imaging data using AI algorithms, all our models outperform the ICM accuracy and achieve comparable TE accuracy. To minimize the role of chance in calculating the models' prediction accuracies, the SWA-Gaussian (SWAG) algorithm was used. SWAG is a method to reflect and calibrate uncertainty representation in Bayesian deep learning. It is based on modelling a Gaussian distribution for each networks' weight and applying it as a posterior over all neural network weights to perform Bayesian model averaging.

Limitations, reasons for caution

To reflect a real IVF lab scenario, embryologists of different origins and levels of experience were involved and no scoring training was offered to the participants. These facts could have potentially negatively affected the degree of consensus, although we excluded two annotators diverging from the mean labeling accuracy.

Wider implications of the findings

In the past, AI algorithms proved to reliably differentiate between good and bad prognosis blastocysts but not necessarily between blastocysts of similar quality. Further AI-supported differentiation on the basis of expansion and cell lineages will facilitate the ranking of blastocysts and would bring automated scoring closer to clinical application.

Trial registration number

Not applicable.

Investigating charge-up and fragmentation dynamics of oxygen molecules after interaction with strong X-ray free-electron laser pulses

The X-ray-induced charge-up and fragmentation process of a small molecule is examined in great detail by measuring the molecular-frame photoelectron interference pattern in conjunction with other observables in coincidence.

MT1 Melatonin Receptor Reconstitution in Nanodiscs

A way to study G protein-coupled receptors in a minimal system is to reconstruct artificial membrane mimics, made of detergent and/or of lipids in which the purified receptor is maintained. In particular, it is now possible to generate lipid nanoparticles, such as nanodiscs, in which a single receptor molecule is included. Such objects offer the invaluable potential of studying an isolated receptor stabilized in a finely controlled membrane-like environment to evaluate its pharmacology, its function, and its structure at the molecular level. In this chapter, we detail the different steps from the extraction and isolation of a recombinant MT1 melatonin receptor in detergent, down to its reconstitution into nanodiscs. A G protein activation test is further described in order to exemplify how the functionality of such particles may be investigated.

Production and Preparation of Isotopically Labeled Human Membrane Proteins in Pichia pastoris for Fast-MAS-NMR Analyses

Membrane proteins (MPs) comprise about one-third of the human proteome, playing critical roles in many physiological processes and associated disorders. Consistently, they represent one of the largest classes of targets for the pharmaceutical industry. Their study at the molecular level is however particularly challenging, resulting in a severe lack of structural and dynamic information that is hindering their detailed functional characterization and the identification of novel potent drug candidates.Magic Angle Spinning (MAS) NMR is a reliable and efficient method for the determination of protein structures and dynamics and for the identification of ligand binding sites and equilibria. MAS-NMR is particularly well suited for MPs since they can be directly analysed in a native-like lipid bilayer environment but used to require aggravating large amounts of isotope enriched material. The frequent toxicity of human MP overexpression in bacterial cultures poses an additional hurdle, resulting in the need for alternative (and often more costly) expression systems. The recent development of very fast (up to 150 kHz) MAS probes has revolutionized the field of biomolecular solid-state NMR enabling higher spectral resolution with significant reduction of the required sample, rendering eukaryotic expression systems cost-effective.Here is presented a set of accessible procedures validated for the production and preparation of eukaryotic MPs for Fast-MAS ¹H-detected NMR analysis. The methodology is illustrated with the human copper uptake protein hCTR1 recombinantly produced and ¹³C-¹⁵N uniformly labeled with the versatile and affordable Pichia pastoris system. Subsequent purification procedures allow the recovery of mg amounts that are then reconstituted into liposome formulations compatible with solid-state NMR handling and analysis.

[Cortisol concentrations in sheep before, during and after sham foot trimming on a tilt table - the suitability of different matrices]

INTRODUCTION

Matrices that can be collected non-invasively for quantification of a stress response in sheep have received little attention in the veterinary literature. This study examines the suitability of blood, tears and saliva for determining a stress response in sheep undergoing sham foot trimming on a tilt table. The cortisol concentration of blood, tears and saliva and the concentration of cortisol metabolites in faeces were measured in 13 healthy Meat Merino ewes once a day for six days. Sham foot trimming on a tilt table was used as the stressor and was done during a one-hour period on day 4; cortisol concentrations of blood and tears were measured at 0, 10, 20, 30, 40 and 60 minutes. Cortisol concentrations of blood (maximum at 30 minutes) and tears (maximum at 40 minutes) increased during the procedure and then decreased. There were significant correlations between cortisol concentrations of blood and tears (p = 0,04) during sham foot trimming (area under the curve, 0 to 60 minutes). Over the entire 6-day study period, significant correlations were seen between the cortisol concentrations of blood and tears (r = 0,55; p.

Fractionation of carbohydrates and proteins and in vitro rumen kinetics of corn silage under various storage durations

The experiment evaluated the effects on the chemical composition (fermentation, kinetic parameters, and protein and carbohydrate fractions) of corn silage after various storage durations (45, 90, 180, and 360 days). Experimental mini silos of the corn plants were made and opened after various storage periods. The experimental design was completely randomized with four treatments and four replications per treatment. Variables such as pH, lactic acid and acetic acid showed a quadratic effect, whereas effluent and gas losses increased linearly with prolonged storage. Proteolysis was observed with an increase in storage, resulting in a rise in ammonia-N, soluble N, and non-protein N concentration and reduction in true protein. The soluble carbohydrate fractions were reduced, and digestible and indigestible fibre were increased. For the kinetic degradation parameters of the silages obtained through in vitro gas methodology, the highest fermentation rate occurred in the first 12 hours of incubation, and the highest volume of gas produced within 96 hours was obtained for silages with shorter storage (45 days). The increase in storage resulted in greater losses and lower ruminal degradability in vitro, causing a decrease in protein quality and nutritional value.

LEAP2 Impairs the Capability of the Growth Hormone Secretagogue Receptor to Regulate the Dopamine 2 Receptor Signaling

The growth hormone secretagogue receptor (GHSR) signals in response to ghrelin, but also acts via ligand-independent mechanisms that include either constitutive activation or interaction with other G protein-coupled receptors, such as the dopamine 2 receptor (D2R). A key target of GHSR in neurons is voltage-gated calcium channels type 2.2 (Ca_V2.2). Recently, the liver-expressed antimicrobial peptide 2 (LEAP2) was recognized as a novel GHSR ligand, but the mechanism of action of LEAP2 on GHSR is not well understood. Here, we investigated the role of LEAP2 on the canonical and non-canonical modes of action of GHSR on Ca_V2.2 function. Using a heterologous expression system and patch-clamp recordings, we found that LEAP2 impairs the reduction of Ca_V2.2 currents induced by ghrelin-evoked and constitutive GHSR activities, acting as a GHSR antagonist and inverse agonist, respectively. We also found that LEAP2 prevents GHSR from modulating the effects of D2R signaling on Ca_V2.2 currents, and that the GHSR-binding N-terminal region LEAP2 underlies these effects. Using purified labeled receptors assembled into lipid nanodiscs and Forster Resonance Energy Transfer (FRET) assessments, we found that the N-terminal region of LEAP2 stabilizes an inactive conformation of GHSR that is dissociated from Gq protein and, consequently, reverses the effect of GHSR on D2R-dependent Gi activation. Thus, our results provide critical molecular insights into the mechanism mediating LEAP2 modulation of GHSR.

Welding fume nanoparticles from solid and flux-cored wires: Solubility, toxicity, and role of fluorides

Welding fume particles are hazardous. Their toxicity likely depends on their composition and reactivity. This study aimed at exploring the role of sodium or other fluorides (NaF), which are intentionally added to flux-cored wire electrodes for stainless steel welding, on the solubility (in phosphate buffered saline) and toxicity of the generated welding fume particles. A multi-analytical particle characterization approach along with in-vitro cell assays was undertaken. The release of Cr(VI) and Mn from the particles was tested as a function of fluoride solution concentration. The welding fume particles containing NaF released significantly higher amounts of Cr(VI) compared with solid wire reference fumes, which was associated with increased cytotoxicity and genotoxicity in-vitro. No crystalline Na or potassium (K) containing chromates were observed. Cr(VI) was incorporated in an amorphous mixed oxide. Solution-added fluorides did not increase the solubility of Cr(VI), but contributed to a reduced Mn release from both solid and flux-cored wire fume particles and the reduction of Cr(VI) release from solid wire fume particles. Chemical speciation modeling suggested that metal fluoride complexes were not formed. The presence of NaF in the welding electrodes did not have any direct, but possibly an indirect, role in the Cr(VI) solubility of welding fumes.

Photon-recoil imaging: Expanding the view of nonlinear x-ray physics

Addressing the ultrafast coherent evolution of electronic wave functions has long been a goal of nonlinear x-ray physics. A first step toward this goal is the investigation of stimulated x-ray Raman scattering (SXRS) using intense pulses from an x-ray free-electron laser. Earlier SXRS experiments relied on signal amplification during pulse propagation through dense resonant media. By contrast, our method reveals the fundamental process in which photons from the primary radiation source directly interact with a single atom. We introduce an experimental protocol in which scattered neutral atoms rather than scattered photons are detected. We present SXRS measurements at the neon K edge and a quantitative theoretical analysis. The method should become a powerful tool in the exploration of nonlinear x-ray physics.

Defining the electrocardiographic and echocardiographic abnormalities in a population of older adults with cardiovascular disease in rural south africa

Background

The African continent is undergoing an epidemiologic transition from infectious to cardiovascular (CV) diseases. National health systems face a critical shortage of population-level data to target the growing burden of hypertension (HTN). Very little is known on the impact of HTN on the rural population in many African countries, where over 85% of the rural population will migrate to cities and shape the modern CV disease spectrum of Africa in the next decade.

Purpose

To characterize the prevalence of HTN and HTN-related EKG and TTE abnormalities in a rural cohort in South Africa (n=5,059).

Methods

Between 2014 and 2015, 804 EKGs and 158 TTEs were performed on participants aged 40 or older randomly sampled from a longitudinal cohort residing in the Agincourt sub-district of rural South Africa. EKGs and TTEs were interpreted by two blinded physicians, and clinically meaningful variables defined using the Minnesota code (EKG) and European Association of Cardiovascular Imaging guidelines (TTE). Chi-square tests were conducted to define the association of EKG/TTE abnormalities with HTN, and stratify by gender.

Results

Over 55% of the sample (n=810) met blood pressure criteria for HTN, with a high prevalence of obesity (29%). On EKG, 36.5% participants had left ventricular hypertrophy (LVH), 13.6% T wave abnormalities, 7.5% Q wave abnormalities and 18.8% prolonged QT interval. Males (n=291) had more LVH (45% vs 30.8%, p<0.01) and Q wave abnormalities (10% vs 5.9%, p=0.04) than females. Instead, females (n=438) had more prolonged QT intervals (28.8% vs 21%, p=0.02). Compared to those without HTN, participants with HTN had more LVH (45.4% vs 22.1%, p<0.01), ST segment abnormalities (17.4% vs 10.7%, p<0.01) and prolonged QT interval (23.4% vs 11.4%, p<0.01). On TTE, there was a high prevalence of moderate (31%) / severe (25.8%) diastolic dysfunction, and concentric LVH (31.6%). Females had more concentric LVH (40.8% vs 13.5%, p<0.01), and high relative wall thickness (70% vs 18.1%, p<0.01) than males. Participants with HTN had more concentric LVH (42.5% vs 8.2%, p<0.01), LV mass (58.5% vs 20.4%, p<0.01) and LV mass index (52.8% vs 30.6%, p<0.01), than those without HTN.

Conclusions

The rural population in South Africa is already affected by a high burden of HTN and high obesity levels. Within this cohort, patients with HTN have significantly more EKG and TTE abnormalities that predict adverse CV outcomes. EKG and TTE evaluation can be used to identify high-risk groups that national health systems should prioritize with frequent monitoring and more aggressive medical treatment.

Funding Acknowledgement

Type of funding source: Private hospital(s). Main funding source(s): Brigham and Women's Hospital

Forensic postmortem computed tomography in suspected unnatural adult deaths

PURPOSE

Our study sought to evaluate validity of forensic postmortem CT in establishing cause of death (COD) in suspected unnatural adult death based on the reference standard of autopsy.

METHODS

In our prospective, single-center study, 64 of 94 consecutive corpses (70.7 % male, mean age: 47.4 years) who underwent CT and autopsy between November 2013 and April 2019 were included in the analysis. Primary objective was agreement between CT and autopsy on primary COD using kappa statistics. Secondary objectives were competing COD and specific pathological findings.

RESULTS

Agreement on primary COD between forensic CT and autopsy without or in consideration of toxicological and histological findings was strong (85.9 % [55 of 64 corpses]; κ = 0.83 [95 %CI: 0.74 to 0.93] and 95.3 % [61 of 64 corpses]; κ = 0.94 [95 %CI: 0.84-1.04], respectively, McNemar p = 0.03). Sensitivity and specificity of CT in identification of acute heart failure, intracranial bleeding, burns and heat shocks, gunshot wounds, polytrauma, cranio-cerebral trauma, and strangulation or hanging was 100 %, each. Acute respiratory failure was detected with a sensitivity and specificity of 100 % and 96.8 %, cuts and stab wounds with 95.2 % and 100 %, and intoxication, pneumonia, or gastrointestinal bleeding with 60.0 % and 100 %, respectively. Agreement on competing COD was moderate (51.6 %, [33 of 64 corpses]; κ = 0.47 [95 %CI: 0.40 to 0.53], p < 0.001).

CONCLUSIONS

Forensic postmortem CT, complemented by external, toxicological, and histological examination was sufficiently valid to assess primary COD in the majority of suspected unnatural deaths with few restrictions.

Size-dependent influence of NOx on the growth rates of organic aerosol particles

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

Preparation of Recombinant Membrane Proteins from Pichia pastoris for Molecular Investigations

Pichia pastoris is a eukaryotic microorganism reputed for its ability to mass-produce recombinant proteins, including integral membrane proteins, for various applications. This article details a series of protocols that progress towards the production of integral membrane proteins, their extraction and purification in the presence of detergents, and their eventual reconstitution in lipid nanoparticles. These basic procedures can be further optimized to provide integral membrane protein samples that are compatible with a number of structural and/or functional investigations at the molecular level. Each protocol provides general guidelines, technical hints, and specific recommendations, and is illustrated with case studies corresponding to several representative mammalian proteins. © 2020 by John Wiley & Sons, Inc. Basic Protocol 1: Production of membrane proteins in a P. pastoris recombinant clone using methanol induction Basic Protocol 2: Preparation of whole-membrane fractions Alternate Protocol 1: Preparation of yeast protoplasts Basic Protocol 3: Extraction of membrane proteins from whole-membrane fractions Basic Protocol 4: Purification of membrane proteins Alternate Protocol 2: Purification of membrane proteins from yeast protoplasts Alternate Protocol 3: Simultaneous protoplast preparation and membrane solubilization for purification of membrane proteins Basic Protocol 5: Reconstitution of detergent-purified membrane proteins in lipid nanoparticles.

Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites

The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.

Gas Chromatographic Method for Putrescine and Cadaverine in Canned Tuna and Mahimahi and Fluorometric Method for Histamine (Minor Modification of AOAC Official Method 977.13): Collaborative Study

A collaborative study was conducted to test a modification to the AOAC fluorometric method for histamine (AOAC® Official Method 977.13) that substitutes 75% methanol as the extracting solvent. All other steps remain unchanged. The extracts prepared with 75% methanol were also used to collaboratively test a gas chromatographic (GC) method for determination of putrescine and cadaverine in seafood. In the GC method, the extracted diamines are converted to fluorinated derivatives, the reaction mixtures are passed through solid-phase extraction columns, and the derivatives are quantitated by electron capture GC after separation on an OV-225 column. Fourteen laboratories using the GC method for putrescine and cadaverine and 16 laboratories using the fluorometric method for histamine analyzed 14 canned tuna and raw mahimahi (including blind duplicates and a spike) containing 0.2-2.6 ppm putrescine, 0.6-9.1 ppm cadaverine, and 0.6-154 ppm histamine. At the 5 ppm level, recoveries ranged from 71 to 102% for putrescine and 77 to 112% for cadaverine; the respective repeatability relative standard deviations (RSDr) were 5.2 and 15%, and the respective reproducibility relative standard deviations (RSDR) were 8.8 and 18%. At the 50 ppm level, histamine recoveries ranged from 84 to 125%, RSDr was 3.6%, and RSDR was 9.4%. The GC method for determination of putrescine in canned tuna and cadaverine in canned tuna and mahimahi has been adopted first action by AOAC INTERNATIONAL, and the AOAC Official Method 977.13, Histamine in Seafood, Fluorometric Method, has been modified

Simultaneous Determination of Multiple Tetracycline Residues in Milk by Metal Chelate Affinity Chromatography: Collaborative Study

To meet federal and state regulatory needs, a liquid chromatographic (LC) method with ultraviolet (UV) detection was developed for determination of 7 tetracyclines at 30 ng/mL in milk. Raw milk samples are defatted, acidified, and centrifuged to remove proteins, and tetracyclines are specifically absorbed from the milk by chelation with metal ions bound to small Chelating Sepharose Fast Flow columns. Tetracyclines are removed from these columns with EDTA-containing buffer, and extracts are further cleaned by ultrafiltration. Finally, extracts are concentrated and analyzed simultane ously by using on-line concentration. This method was validated in a collaborative study that involved 11 laboratories, including the authors’ laboratory. Each laboratory was asked to prepare and analyze known control and fortified milk samples, as well as 18 coded blind samples. Eight laboratories completed all analyses. Average interlaboratory recoveries for the known fortified samples ranged from 59% (methacycline at 15 ng/mL) to 78% (oxytetracy cline at 60 ng/mL). Average recovery for each of 7 residues at 30 ng/mL were between 60 and 110%, meeting single-residue guidelines for accuracy set by the U.S. Food and Drug Administration. Reproducibility relative standard deviation (RSDR) for the known fortified samples varied from 11 to 39%, with 6 of 7 residues at the 30 ng/mL level having RSDR values at or below 20%. Seven of 8 laboratories correctly identified blind control milk samples and all 28 residues present in blind samples. The metal chelate affinity—LC method for determination of multiple tetracycline residues in milk has been adopted first action by AOAC INTERNATIONAL.

Recombinant HIV-1 vaccine candidates based on replication-defective flavivirus vector

Multiple approaches utilizing viral and DNA vectors have shown promise in the development of an effective vaccine against HIV. In this study, an alternative replication-defective flavivirus vector, RepliVax (RV), was evaluated for the delivery of HIV-1 immunogens. Recombinant RV-HIV viruses were engineered to stably express clade C virus Gag and Env (gp120TM) proteins and propagated in Vero helper cells. RV-based vectors enabled efficient expression and correct maturation of Gag and gp120TM proteins, were apathogenic in a sensitive suckling mouse neurovirulence test, and were similar in immunogenicity to recombinant poxvirus NYVAC-HIV vectors in homologous or heterologous prime-boost combinations in mice. In a pilot NHP study, immunogenicity of RV-HIV viruses used as a prime or boost for DNA or NYVAC candidates was compared to a DNA prime/NYVAC boost benchmark scheme when administered together with adjuvanted gp120 protein. Similar neutralizing antibody titers, binding IgG titers measured against a broad panel of Env and Gag antigens, and ADCC responses were observed in the groups throughout the course of the study, and T cell responses were elicited. The entire data demonstrate that RV vectors have the potential as novel HIV-1 vaccine components for use in combination with other promising candidates to develop new effective vaccination strategies.

VHH characterization. Comparison of recombinant with chemically synthesized anti-HER2 VHH

In the continuous exploration of the VHH chemistry, biochemistry and therapeutic future use, we investigated two different production strategies of this small antibody-like protein, using an anti-HER2 VHH as a model. The total chemical synthesis of the 125 amino-acid peptide was performed with reasonable yield, even if optimization will be necessary to upgrade this kind of production. In parallel, we expressed the same sequence in two different hosts: Escherichia coli and Pichia pastoris. Both productions were successful and led to a fair amount of VHHs. The integrity and conformation of the VHH were characterized by complementary mass spectrometry approaches, while surface plasmon resonance experiments were used to assess the VHH recognition capacity and affinity toward its "antigen." Using this combination of orthogonal techniques, it was possible to show that the three VHHs-whether synthetic or recombinant ones-were properly and similarly folded and recognized the "antigen" HER2 with similar affinities, in the nanomolar range. This opens a route toward further exploration of modified VHH with unnatural amino acids and subsequently, VHH-drug conjugates.

Pedestrian hit by a car impacted metal pole: reconstructing the head load

Fatal head injuries are frequently seen in pedestrians hit by motorized vehicles. In our case, the pedestrian sustained a devastating head injury with skull splitting in the mediosagittal plane. A car collided with a traffic sign causing a bending of the pole. The metal pole hit a man standing close beside it; the man had a head injury severity that is more commonly due to falling objects than due to traffic accidents. Assuming a head mass of 5 kg, simplified calculations yield maximum contact forces of ca. 36 kN exceeding mean parietal fracture forces which are in the order of magnitude of 12.5 kN. The influences of the effective body mass and the horizontal distance between the pole and the pedestrian on maximum contact forces are investigated. High contact forces in our case can be mainly explained by the comparably high impact velocity and by a partial mass transfer of the total car mass to the pole.

Efectos del aceite esencial de Eucalyptus globulus cargado en nanoemulsiones y en nanocápsulas en la reproducción de la garrapata bovina (Rhipicephalus microplus)

La infestación por garrapatas (Rhipicephalus microplus), genera importantes pérdidas en la producción bovina. El objetivo de este estudio fue investigar si el aceite esencial de Eucalyptus globulus en diferentes nanosistemas (nanoemulsiones y nanocápsulas) es capaz de potenciar el efecto negativo sobre la reproducción de la garrapata, interfiriendo en su oviposición y eclosión de los huevos. Las hembras engordadas de R. microplus se obtuvieron de vacas naturalmente infestadas. En condiciones experimentales, estas hembras fueron sumergidas en soluciones de ensayo a concentraciones de 1, 5 y 10%, conteniendo aceite esencial puro de eucalipto; Y soluciones de la misma en nanocápsulas y nanoemulsiones, a concentraciones de 0,5, 1 y 5%. Las pruebas con aceite esencial de eucalipto puro, a concentraciones de 5 y 10%, mostraron 85 y 97,8% de eficacia, respectivamente. Sin embargo, el aceite encapsulado no fue capaz de potenciar el efecto carrapaticida, presentando 61,2% y 50% de eficacia (al 5%), utilizando nanoemulsiones y nanocápsulas. Por lo tanto, nuestros resultados nos permitieron concluir que el aceite esencial de E. globulus, en su forma pura, interfería negativamente en la reproducción de R. microplus; Sin embargo, las formas nanoestructuradas tenían baja eficacia.

Effects of feeding legume-grass pasture and different concentrate levels on fatty acid profile, volatile compounds, and off-flavor of the M. longissimus thoracis

Pasture-finished beef is becoming more popular among consumers due to concerns related to fatty acid content and sustainable practices. The effects of finishing crossbred steers on legume-grass pasture comprised of oats, ryegrass, and clover (PAST), legume-grass pasture plus whole corn grain (WCG) supplementation (SUPP), and only with WCG (GRAIN) on fatty acids profile, volatile compounds, sensory, and texture attributes were studied. Pasture diets (PAST and SUPP) led to lower n-6/n-3 ratio (P < 0.001), and highest deposition of C18:2 cis-9 trans-11 (P < 0.001) in the lean. Beef from steers fed GRAIN had the highest values of volatile compounds associated with lipid oxidation. Off-flavor intensity was significantly greater on beef from steers fed GRAIN when compared to PAST. Overall, muscles from steers finished on PAST and SUPP showed similar attributes but differ when compared to GRAIN. The presence of forage is essential to improve fatty acid profile, decrease volatile compounds associated with lipid oxidation, and minimize off-flavor.