Mathematical Model-Driven Deep Learning Enables Personalized Adaptive Therapy.

Standard-of-care treatment regimens have long been designed for maximal cell killing, yet these strategies often fail when applied to metastatic cancers due to the emergence of drug resistance. Adaptive treatment strategies have been developed as an alternative approach, dynamically adjusting treatment to suppress the growth of treatment-resistant populations and thereby delay, or even prevent, tumor progression. Promising clinical results in prostate cancer indicate the potential to optimize adaptive treatment protocols. Here, we applied deep reinforcement learning (DRL) to guide adaptive drug scheduling and demonstrated that these treatment schedules can outperform the current adaptive protocols in a mathematical model calibrated to prostate cancer dynamics, more than doubling the time to progression. The DRL strategies were robust to patient variability, including both tumor dynamics and clinical monitoring schedules. The DRL framework could produce interpretable, adaptive strategies based on a single tumor burden threshold, replicating and informing optimal treatment strategies. The DRL framework had no knowledge of the underlying mathematical tumor model, demonstrating the capability of DRL to help develop treatment strategies in novel or complex settings. Finally, a proposed five-step pathway, which combined mechanistic modeling with the DRL framework and integrated conventional tools to improve interpretability compared to traditional "black-box" DRL models, could allow translation of this approach to the clinic. Overall, the proposed framework generated personalized treatment schedules that consistently outperformed clinical standard-of-care protocols.

The Andes as a semi-permeable geographical barrier: Genetic connectivity between structured populations in a widespread spider.

Geographical barriers like mountain ranges impede genetic exchange among populations, promoting diversification. The effectiveness of these barriers in limiting gene flow varies between lineages due to each species' dispersal modes and capacities. Our understanding of how the Andes orogeny contributes to species diversification comes from well-studied vertebrates and a few arthropods and plants, neglecting organisms unable to fly or walk long distances. Some arachnids, such as Gasteracantha cancriformis, have been hypothesized to disperse long distances via ballooning (i.e. using their silk to interact with the wind). Yet, we do not know how the environment and geography shape its genetic diversity. Therefore, we tested whether the Andes contributed to the diversification of G. cancriformis acting as an absolute or semi-permeable barrier to genetic connectivity between populations of this spider at opposite sides of the mountain range. We sampled thousands of loci across the distribution of the species and implemented population genetics, phylogenetic, and landscape genetic analyses. We identified two genetically distinct groups structured by the Central Andes, and a third less structured group in the Northern Andes that shares ancestry with the previous two. This structure is largely explained by the altitude along the Andes, which decreases in some regions, possibly facilitating cross-Andean dispersal and gene flow. Our findings support that altitude in the Andes plays a major role in structuring populations in South America, but the strength of this barrier can be overcome by organisms with long-distance dispersal modes together with altitudinal depressions.

Las barreras geográficas como las cordilleras montañosas impiden el intercambio genético entre poblaciones, promoviendo la diversificación. La efectividad de estas barreras para limitar el flujo genético varía entre linajes debido a los modos y capacidades de dispersión de cada especie. Nuestra comprensión de cómo la orogenia de los Andes contribuye a la diversificación de especies proviene de vertebrados y algunos artrópodos y plantas bien estudiados, descuidando a los organismos incapaces de volar o caminar grandes distancias. Se ha hipotetizado que algunas arañas, como Gasteracantha cancriformis, se dispersan a grandes distancias mediante la técnica de "ballooning" (es decir, utilizando su seda para interactuar con el viento). Sin embargo, no sabemos cómo el entorno y la geografía han dado forma a su diversidad genética. Por lo tanto, probamos si los Andes contribuyeron a la diversificación de G. cancriformis actuando como una barrera absoluta o permeable para la conectividad genética entre poblaciones de esta araña en lados opuestos de la cordillera. Muestreamos miles de loci a través de la distribución de la especie e implementamos análisis de genética de poblaciones, filogenéticos y de genética del paisaje. Identificamos dos grupos genéticamente distintos estructurados por los Andes Centrales, y un tercer grupo menos estructurado en los Andes del Norte que comparte ascendencia con los dos anteriores. Esta estructura se explica en gran medida por la altitud a lo largo de los Andes, que disminuye en algunas regiones, posiblemente facilitando la dispersión y el flujo genético a través de los Andes. Nuestros hallazgos apoyan que la altitud en los Andes juega un papel importante en la estructuración de las poblaciones en América del Sur, pero la fuerza de esta barrera puede ser superada por organismos con modos de dispersión a larga distancia junto con depresiones altitudinales.

Case report: C1/2 rotational instability progressing to extreme subaxial hyperkyphosis in an adolescent with severe catatonia.

Introduction: Autism spectrum disorder (ASD) is characterized by deficits in social communication, repetitive behaviors, and can be accompanied by a spectrum of psychiatric symptoms, such as schizophrenia and catatonia. Rarely, these symptoms, if left untreated, can result in spinal deformities. Research question and case description: This case report details the treatment of a 16-year-old male ASD patient with catatonic schizophrenia and mutism, presenting with neck pain, left-rotated torticollis, and fever. MRI revealed atlantoaxial rotational instability and spinal cord compression from a dislocated dens axis. After inconclusive biopsies, empirical antibiotics, hard collar and halo fixation treatment, persistent instability necessitated C1/2 fusion. The ongoing catatonia was addressed with electroconvulsive therapy. Concurrently, he developed severe subaxial hyperkyphosis. The report examines the decision-making between conservative and surgical management for an adolescent with significant psychiatric comorbidity and progressive spinal symptoms against a backdrop of uncertain etiology. Materials and methods: A case report and review of the literature. Results: Posterior C1-C7 stabilization was successfully executed, effectively restoring cervical sagittal alignment, which was maintained throughout a two-year follow-up. Concurrently, the catatonia resolved. Discussion and conclusion: To our knowledge, this is the third reported case of severe cervical deformity associated with fixed posture in a psychiatric patient. This case report emphasizes the critical importance of multidisciplinary collaboration in managing the interplay between neuropsychiatric disorders and severe spinal deformities. It showcases the practicality and efficacy of surgical intervention for persistent cervical deformity in pediatric schizophrenia patients, highlighting the necessity for a comprehensive risk-benefit analysis.

A scalable synthesis of adjuvanting antigen depots based on metal-organic frameworks.

Vaccines have saved countless lives by preventing and even irradicating infectious diseases. Commonly used subunit vaccines comprising one or multiple recombinant proteins isolated from a pathogen demonstrate a better safety profile than live or attenuated vaccines. However, the immunogenicity of these vaccines is weak, and therefore, subunit vaccines require a series of doses to achieve sufficient immunity against the pathogen. Here, we show that the biomimetic mineralization of the inert model antigen, ovalbumin (OVA), in zeolitic imidazolate framework-8 (ZIF-8) significantly improves the humoral immune response over three bolus doses of OVA (OVA 3×). Encapsulation of OVA in ZIF-8 (OVA@ZIF) demonstrated higher serum antibody titers against OVA than OVA 3×. OVA@ZIF vaccinated mice displayed higher populations of germinal center (GC) B cells and IgG1+ GC B cells as opposed to OVA 3×, indicative of class-switching recombination. We show that the mechanism of this phenomenon is at least partly owed to the metalloimmunological effects of the zinc metal as well as the sustained release of OVA from the ZIF-8 composite. The system acts as an antigen reservoir for antigen-presenting cells to traffic into the draining lymph node, enhancing the humoral response. Lastly, our model system OVA@ZIF is produced quickly at the gram scale in a laboratory setting, sufficient for up to 20 000 vaccine doses.

Structural Analysis of Breast-Milk αS1-Casein: An α-Helical Conformation Is Required for TLR4-Stimulation.

Breast-milk αS1-casein is a Toll-like receptor 4 (TLR4) agonist, whereas phosphorylated αS1-casein does not bind TLR4. The objective of this study was to analyse the structural requirements for these effects. In silico analysis of αS1-casein indicated high α-helical content with coiled-coil characteristics. This was confirmed by CD-spectroscopy, showing the α-helical conformation to be stable between pH 2 and 7.4. After in vitro phosphorylation, the α-helical content was significantly reduced, similar to what it was after incubation at 80 °C. This conformation showed no in vitro induction of IL-8 secretion via TLR4. A synthetic peptide corresponding to V77-E92 of αS1-casein induced an IL-8 secretion of 0.95 ng/mL via TLR4. Our results indicate that αS1-casein appears in two distinct conformations, an α-helical TLR4-agonistic and a less α-helical TLR4 non-agonistic conformation induced by phosphorylation. This is to indicate that the immunomodulatory role of αS1-casein, as described before, could be regulated by conformational changes induced by phosphorylation.

Impact of sex and gender on post-COVID-19 syndrome, Switzerland, 2020.

BackgroundWomen are overrepresented among individuals with post-acute sequelae of SARS-CoV-2 infection (PASC). Biological (sex) as well as sociocultural (gender) differences between women and men might account for this imbalance, yet their impact on PASC is unknown.AimWe assessed the impact of sex and gender on PASC in a Swiss population.MethodOur multicentre prospective cohort study included 2,856 (46% women, mean age 44.2 ± 16.8 years) outpatients and hospitalised patients with PCR-confirmed SARS-CoV-2 infection.ResultsAmong those who remained outpatients during their first infection, women reported persisting symptoms more often than men (40.5% vs 25.5% of men; p < 0.001). This sex difference was absent in hospitalised patients. In a crude analysis, both female biological sex (RR = 1.59; 95% CI: 1.41-1.79; p < 0.001) and a score summarising gendered sociocultural variables (RR = 1.05; 95% CI: 1.03-1.07; p < 0.001) were significantly associated with PASC. Following multivariable adjustment, biological female sex (RR = 0.96; 95% CI: 0.74-1.25; p = 0.763) was outperformed by feminine gender-related factors such as a higher stress level (RR = 1.04; 95% CI: 1.01-1.06; p = 0.003), lower education (RR = 1.16; 95% CI: 1.03-1.30; p = 0.011), being female and living alone (RR = 1.91; 95% CI: 1.29-2.83; p = 0.001) or being male and earning the highest income in the household (RR = 0.76; 95% CI: 0.60-0.97; p = 0.030).ConclusionSpecific sociocultural parameters that differ in prevalence between women and men, or imply a unique risk for women, are predictors of PASC and may explain, at least in part, the higher incidence of PASC in women. Once patients are hospitalised during acute infection, sex differences in PASC are no longer evident.

Occurrence of Major Perfluorinated Alkylate Substances in Human Blood and Target Organs.

Human exposure to perfluorinated alkylate substances (PFASs) is usually assessed from the concentrations in serum or plasma, assuming one-compartment toxicokinetics. To characterize body distributions of major PFASs, we obtained and extracted tissue samples from 19 forensic autopsies of healthy adult subjects who had died suddenly and were not known to have elevated levels of PFAS exposure. As target organs of toxicological importance, we selected the liver, kidneys, lungs, spleen, and brain, as well as whole blood. Samples weighing about 0.1 g were analyzed by liquid chromatography coupled to triple mass spectrometers. Minor variations in PFAS concentrations were found between the kidney cortex and medulla and between lung lobes. Organ concentrations of perfluorooctanoic sulfonate (PFOS) and perfluorononanoate (PFNA) correlated well with blood concentrations, while perfluorooctanoate (PFOA) and perfluorohexanoic sulfonate (PFHxS) showed more variable associations. Likewise, the liver concentrations correlated well with those of other organs. Calculations of relative distributions were carried out to assess the interdependence of organ retentions. Equilibrium model predictions largely explained the observed PFAS distributions, except for the brain. Although the samples were small and affected by a possible lack of homogeneity, these findings support the use of blood-PFAS concentrations as a measure of PFAS exposure, with the liver possibly acting as the main organ of retention.

On-Command Disassembly of Microrobotic Superstructures for Transport and Delivery of Magnetic Micromachines.

Magnetic microrobots have been developed for navigating microscale environments by means of remote magnetic fields. However, limited propulsion speeds at small scales remain an issue in the maneuverability of these devices as magnetic force and torque are proportional to their magnetic volume. Here, a microrobotic superstructure is proposed, which, as analogous to a supramolecular system, consists of two or more microrobotic units that are interconnected and organized through a physical (transient) component (a polymeric frame or a thread). The superstructures consist of microfabricated magnetic helical micromachines interlocked by a magnetic gelatin nanocomposite containing iron oxide nanoparticles (IONPs). While the microhelices enable the motion of the superstructure, the IONPs serve as heating transducers for dissolving the gelatin chassis via magnetic hyperthermia. In a practical demonstration, the superstructure's motion with a gradient magnetic field in a large channel, the disassembly of the superstructure and release of the helical micromachines by a high-frequency alternating magnetic field, and the corkscrew locomotion of the released helices through a small channel via a rotating magnetic field, is showcased. This adaptable microrobotic superstructure reacts to different magnetic inputs, which can be used to perform complex delivery procedures within intricate regions of the human body.

In Silico and In Vitro Search for Dual Inhibitors of the Trypanosoma brucei and Leishmania major Pteridine Reductase 1 and Dihydrofolate Reductase.

The parasites Trypanosoma brucei (Tb) and Leishmania major (Lm) cause the tropical diseases sleeping sickness, nagana, and cutaneous leishmaniasis. Every year, millions of humans, as well as animals, living in tropical to subtropical climates fall victim to these illnesses' health threats. The parasites' frequent drug resistance and widely spread natural reservoirs heavily impede disease prevention and treatment. Due to pteridine auxotrophy, trypanosomatid parasites have developed a peculiar enzyme system consisting of dihydrofolate reductase-thymidylate synthase (DHFR-TS) and pteridine reductase 1 (PTR1) to support cell survival. Extending our previous studies, we conducted a comparative study of the T. brucei (TbDHFR, TbPTR1) and L. major (LmDHFR, LmPTR1) enzymes to identify lead structures with a dual inhibitory effect. A pharmacophore-based in silico screening of three natural product databases (approximately 4880 compounds) was performed to preselect possible inhibitors. Building on the in silico results, the inhibitory potential of promising compounds was verified in vitro against the recombinant DHFR and PTR1 of both parasites using spectrophotometric enzyme assays. Twelve compounds were identified as dual inhibitors against the Tb enzymes (0.2 µM < IC50 < 85.1 µM) and ten against the respective Lm enzymes (0.6 µM < IC50 < 84.5 µM). These highly promising results may represent the starting point for the future development of new leads and drugs utilizing the trypanosomatid pteridine metabolism as a target.

Improved computational epitope profiling using structural models identifies a broader diversity of antibodies that bind to the same epitope.

The function of an antibody is intrinsically linked to the epitope it engages. Clonal clustering methods, based on sequence identity, are commonly used to group antibodies that will bind to the same epitope. However, such methods neglect the fact that antibodies with highly diverse sequences can exhibit similar binding site geometries and engage common epitopes. In a previous study, we described SPACE1, a method that structurally clustered antibodies in order to predict their epitopes. This methodology was limited by the inaccuracies and incomplete coverage of template-based modeling. In addition, it was only benchmarked at the level of domain-consistency on one virus class. Here, we present SPACE2, which uses the latest machine learning-based structure prediction technology combined with a novel clustering protocol, and benchmark it on binding data that have epitope-level resolution. On six diverse sets of antigen-specific antibodies, we demonstrate that SPACE2 accurately clusters antibodies that engage common epitopes and achieves far higher dataset coverage than clonal clustering and SPACE1. Furthermore, we show that the functionally consistent structural clusters identified by SPACE2 are even more diverse in sequence, genetic lineage, and species origin than those found by SPACE1. These results reiterate that structural data improve our ability to identify antibodies that bind to the same epitope, adding information to sequence-based methods, especially in datasets of antibodies from diverse sources. SPACE2 is openly available on GitHub (https://github.com/oxpig/SPACE2).

Paired Liver:Plasma PFAS Concentration Ratios from Adolescents in the Teen-LABS Study and Derivation of Empirical and Mass Balance Models to Predict and Explain Liver PFAS Accumulation.

Animal studies have pointed at the liver as a hotspot for per- and polyfluoroalkyl substances (PFAS) accumulation and toxicity; however, these findings have not been replicated in human populations. We measured concentrations of seven PFAS in matched liver and plasma samples collected at the time of bariatric surgery from 64 adolescents in the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study. Liver:plasma concentration ratios were perfectly explained (r2 > 0.99) in a multilinear regression (MLR) model based on toxicokinetic (TK) descriptors consisting of binding to tissue constituents and membrane permeabilities. Of the seven matched plasma and liver PFAS concentrations compared in this study, the liver:plasma concentration ratio of perfluoroheptanoic acid (PFHpA) was considerably higher than the liver:plasma concentration ratio of other PFAS congeners. Comparing the MLR model with an equilibrium mass balance model (MBM) suggested that complex kinetic transport processes are driving the unexpectedly high liver:plasma concentration ratio of PFHpA. Intratissue MBM modeling pointed to membrane lipids as the tissue constituents that drive the liver accumulation of long-chain, hydrophobic PFAS, whereas albumin binding of hydrophobic PFAS dominated PFAS distribution in plasma. The liver:plasma concentration data set, empirical MLR model, and mechanistic MBM modeling allow the prediction of liver from plasma concentrations measured in human cohort studies. Our study demonstrates that combining biomonitoring data with mechanistic modeling can identify underlying mechanisms of internal distribution and specific target organ toxicity of PFAS in humans.

Interaction of Substrates with γ-Secretase at the Level of Individual Transmembrane Helices-A Methodological Approach.

Intramembrane proteases, such as γ secretase, typically recruit multiple substrates from an excess of single-span membrane proteins. It is currently unclear to which extent substrate recognition depends on specific interactions of their transmembrane domains (TMDs) with TMDs of a protease. Here, we investigated a large number of potential pairwise interactions between TMDs of γ secretase and a diverse set of its substrates using two different configurations of BLaTM, a genetic reporter system. Our results reveal significant interactions between TMD2 of presenilin, the enzymatic subunit of γ secretase, and the TMD of the amyloid precursor protein, as well as of several other substrates. Presenilin TMD2 is a prime candidate for substrate recruitment, as has been shown from previous studies. In addition, the amyloid precursor protein TMD enters interactions with presenilin TMD 4 as well as with the TMD of nicastrin. Interestingly, the Gly-rich interfaces between the amyloid precursor protein TMD and presenilin TMDs 2 and 4 are highly similar to its homodimerization interface. In terms of methodology, the economics of the newly developed library-based method could prove to be a useful feature in related future work for identifying heterotypic TMD-TMD interactions within other biological contexts.

The heat is on: Investigating the effect of psychological pressure on competitive performance in elite surfing.

Competitive sport often creates a high-stake and thus a high-pressure environment for its athletes. In the past, research has pointed to the negative effect that competitive pressure might have on skills and movement executions that have been perfected through prior practice. The Attentional Control Theory: Sport (ACTS) suggests that specifically high situational pressure and prior performance failures may negatively affect an athlete's subsequent performance. This study aimed to investigate the influence of situational pressure and previous performance errors on performance (i.e., wave score) in elite surfing while considering various contextual factors. A total of 6497 actions, performed by 80 elite surfers (female n = 28; male n = 52), were annotated based on video recordings of the 2019 World Championship Tour (WCT). A multi-level model was used to analyse the effect of pressure, previous errors and other contextual factors on the wave scores of individual surfers (i.e., events were nested within athletes). Partially confirming previous research, prior errors caused a significant decrease in surfing performance on the following ride. However, neither a significant effect of situational pressure on performance nor inter-individual differences in how prior-errors and situational pressure affected performance were found.

Self-assembly of a fluorescent virus-like particle for imaging in tissues with high autofluorescence.

Virus-like particles (VLPs) are engineered nanoparticles that mimic the properties of viruses-like high tolerance to heat and proteases-but lack a viral genome, making them non-infectious. They are easily modified chemically and genetically, making them useful in drug delivery, enhancing vaccine efficacy, gene delivery, and cancer immunotherapy. One such VLP is Qß, which has an affinity towards an RNA hairpin structure found in its viral RNA that drives the self-assembly of the capsid. It is possible to usurp the native way infectious Qß self-assembles to encapsidate its RNA to place enzymes inside the VLP's lumen as a protease-resistant cage. Further, using RNA templates that mimic the natural self-assembly of the native capsid, fluorescent proteins (FPs) have been placed inside VLPs in a "one pot" expression system. Autofluorescence in tissues can lead to misinterpretation of results and unreliable science, so we created a single-pot expression system that uses the fluorescent protein smURFP, which avoids autofluorescence and has spectral properties compatible with standard commercial filter sets on confocal microscopes. In this work, we were able to simplify the existing "one-pot" expression system while creating high-yielding fluorescent VLP nanoparticles that could easily be imaged inside lung epithelial tissue.

Fe- and B-Chains in the Ti5-xFe1-yOs6+x+yB6 Structure Type Derived from Chemical Twinning of the Nb1-xOs1+xB Type: Experimental and Computational Investigations.

The complex metal-rich boride Ti5-xFe1-yOs6+x+yB6 (0 < x,y < 1), crystallizing in a new structure type (space group Cmcm, no. 63), was prepared by arc-melting. The new structure contains both isolated boron atoms and zigzag boron chains (B-B distance of 1.74 Å), a rare combination among metal-rich borides. In addition, the structure also contains Fe-chains running parallel to the B-chains. Unlike in previously reported structures, these Fe-chains are offset from each other and arranged in a triangular manner with intrachain and interchain distances of 2.98 and 6.69 Å, respectively. Density functional theory (DFT) calculations predict preferred ferromagnetic interactions within each chain but only small energy differences for different magnetic interactions between them, suggesting a potentially weak long-range order. This new structure offers the opportunity to study new configurations and interactions of magnetic elements for the design of magnetic materials.

Early Target Attainment With Continuous Infusion Meropenem and Piperacillin/Tazobactam and Utilization of Therapeutic Drug Monitoring in Critically Ill Patients: A Retrospective Cohort Study From 2017 to 2020.

Background: We analyzed the attainment of early pharmacological targets of continuous infusion meropenem and piperacillin/tazobactam and the use and effect of a real-time therapeutic drug monitoring (TDM) program on subsequent dosing and target attainment in patients who are critically ill. Methods: This was a single-center, retrospective study among patients hospitalized in the intensive care unit in a Swiss tertiary care hospital from 2017 to 2020. The primary outcome was target attainment [100% tT ≥ 4xECOFF (Pseudomonas aeruginosa)] of continuous infusion meropenem and piperacillin/tazobactam within 72 hours after initiation of treatment. Results: A total of 234 patients were included. Median first meropenem (n = 186 of 234) and piperacillin (n = 48 of 234) concentration was 21 mg/L (interquartile range [IQR], 15.6-28.6) and 100.7 mg/L (IQR, 64.0-160.2), respectively. Pharmacological target was attained in 95.7% (95% confidence interval [CI], 91.7-98.1) of patients receiving meropenem and 77.0% (95% CI, 62.7-87.9) treated with piperacillin/tazobactam. In the univariable and multivariable logistic regression, body weight and estimated glomerular filtration rate were negatively associated with target attainment. Subsequently, meropenem dosage was decreased or stopped in 35 of 186 (18.8%) and 89 of 186 (47.9%) patients, respectively, and increased in 2 of 186 (1.1%) patients. Conclusions: Continuous infusion meropenem and piperacillin/tazobactam yielded excellent and moderate early pharmacological target attainment in critically ill patients, respectively. The TDM was mainly used to decrease meropenem dosage.

A gene-level test for directional selection on gene expression.

Most variants identified in human genome-wide association studies and scans for selection are noncoding. Interpretation of their effects and the way in which they contribute to phenotypic variation and adaptation in human populations is therefore limited by our understanding of gene regulation and the difficulty of confidently linking noncoding variants to genes. To overcome this, we developed a gene-wise test for population-specific selection based on combinations of regulatory variants. Specifically, we use the QX statistic to test for polygenic selection on cis-regulatory variants based on whether the variance across populations in the predicted expression of a particular gene is higher than expected under neutrality. We then applied this approach to human data, testing for selection on 17,388 protein-coding genes in 26 populations from the Thousand Genomes Project. We identified 45 genes with significant evidence (FDR<0.1) for selection, including FADS1, KHK, SULT1A2, ITGAM, and several genes in the HLA region. We further confirm that these signals correspond to plausible population-level differences in predicted expression. While the small number of significant genes (0.2%) is consistent with most cis-regulatory variation evolving under genetic drift or stabilizing selection, it remains possible that there are effects not captured in this study. Our gene-level QX score is independent of standard genomic tests for selection, and may therefore be useful in combination with traditional selection scans to specifically identify selection on regulatory variation. Overall, our results demonstrate the utility of combining population-level genomic data with functional data to understand the evolution of gene expression.

Process Development for the Spray-Drying of Probiotic Bacteria and Evaluation of the Product Quality.

Probiotics and prebiotics are of great interest to the food and pharmaceutical industries due to their health benefits. Probiotics are live bacteria that can confer beneficial effects on human and animal wellbeing, while prebiotics are types of nutrients that feed the beneficial gut bacteria. Powder probiotics have gained popularity due to the ease and practicality of their ingestion and incorporation into the diet as a food supplement. However, the drying process interferes with cell viability since high temperatures inactivate probiotic bacteria. In this context, this study aimed to present all the steps involved in the production and physicochemical characterization of a spray-dried probiotic and evaluate the influence of the protectants (simulated skim milk and inulin:maltodextrin association) and drying temperatures in increasing the powder yield and cell viability. The results showed that the simulated skim milk promoted higher probiotic viability at 80 °C. With this protectant, the probiotic viability, moisture content, and water activity (Aw) reduce as long as the inlet temperature increases. The probiotics' viability decreases conversely with the drying temperature. At temperatures close to 120 °C, the dried probiotic showed viability around 90%, a moisture content of 4.6% w/w, and an Aw of 0.26; values adequate to guarantee product stability. In this context, spray-drying temperatures above 120 °C are required to ensure the microbial cells' viability and shelf-life in the powdered preparation and survival during food processing and storage.

Different transmembrane domains determine the specificity and efficiency of the cleavage activity of the γ-secretase subunit presenilin.

The γ-secretase complex catalyzes the intramembrane cleavage of C99, a carboxy-terminal fragment of the amyloid precursor protein. Two paralogs of its catalytic subunit presenilin (PS1 and PS2) are expressed which are autocatalytically cleaved into an N-terminal and a C-terminal fragment during maturation of γ-secretase. In this study, we compared the efficiency and specificity of C99 cleavage by PS1- and PS2-containing γ-secretases. Mass spectrometric analysis of cleavage products obtained in cell-free and cell-based assays revealed that the previously described lower amyloid-ß (Aß)38 generation by PS2 is accompanied by a reciprocal increase in Aß37 production. We further found PS1 and PS2 to show different preferences in the choice of the initial cleavage site of C99. However, the differences in Aß38 and Aß37 generation appear to mainly result from altered subsequent stepwise cleavage of Aß peptides. Apart from these differences in cleavage specificity, we confirmed a lower efficiency of initial C99 cleavage by PS2 using a detergent-solubilized γ-secretase system. By investigating chimeric PS1/2 molecules, we show that the membrane-embedded, nonconserved residues of the N-terminal fragment mainly account for the differential cleavage efficiency and specificity of both presenilins. At the level of individual transmembrane domains (TMDs), TMD3 was identified as a major modulator of initial cleavage site specificity. The efficiency of endoproteolysis strongly depends on nonconserved TMD6 residues at the interface to TMD2, i.e., at a putative gate of substrate entry. Taken together, our results highlight the role of individual presenilin TMDs in the cleavage of C99 and the generation of Aß peptides.

Factors impacting the pre-analytical quality of blood cultures-Analysis at a tertiary medical center.

BACKGROUND: Blood cultures (BC) are critical for the diagnosis of bloodstream infections, pathogen identification, and resistance testing. Guidelines recommend a blood volume of 8-10 mL per bottle as lower volumes result in decreased sensitivity. We aimed to evaluate factors for non-adherence to recommended volumes and assess the effects on diagnostic performance. METHODS: From February to April 2020, we measured collected blood volumes by weighing all BC containers from inpatient samples at the University Hospital Basel. Information on BC volumes was merged with clinical and microbiological data, as well as nursing staff schedules. We analyzed factors associated with (i) BC sampling volume, (ii) reaching recommended volumes (≥8 mL), (iii) BC positivity, and (iv) time to positivity using linear and generalized linear mixed effect models. RESULTS: We evaluated a total of 4'118 BC bottles collected from 686 patients. A total of 1'495 (36.3%) of all bottles contained the recommended filling volume of ≥8 mL. Using a central venous and arterial catheter for drawing blood resulted in an increase of filling volume by 0.26 mL (95% CI 0.10, 0.41) and 0.50 mL (95% CI 0.31, 0.69) compared to peripheral venipuncture, respectively. Each additional nursing staff working at the time of blood drawing was associated with 6% higher odds of achieving the recommended filling volume. We found no significant correlation between the filling volume and the positivity rate. CONCLUSION: Our results indicate critical pre-analytical quality markers linked to BC collection procedures to reach recommended collection volumes. No significant impact on the positivity rate was found.