Hippocampal subfield plasticity is associated with improved spatial memory.

Physical exercise studies are generally underrepresented in young adulthood. Seventeen subjects were randomized into an intervention group (24.2 ± 3.9 years; 3 trainings/week) and 10 subjects into a passive control group (23.7 ± 4.2 years), over a duration of 6 months. Every two months, performance diagnostics, computerized spatial memory tests, and 3 Tesla magnetic resonance imaging were conducted. Here we find that the intervention group, compared to controls, showed increased cardiorespiratory fitness, spatial memory performance and subregional hippocampal volumes over time. Time-by-condition interactions occurred in right cornu ammonis 4 body and (trend only) dentate gyrus, left hippocampal tail and left subiculum. Increases in spatial memory performance correlated with hippocampal body volume changes and, subregionally, with left subicular volume changes. In conclusion, findings support earlier reports of exercise-induced subregional hippocampal volume changes. Such exercise-related plasticity may not only be of interest for young adults with clinical disorders of hippocampal function, but also for sedentary normal cohorts.

Prevalence and management of sleep disturbance in adults with primary brain tumours and their caregivers: a systematic review.

PURPOSE: The aims of this systematic review were to (1) examine the prevalence, severity, manifestations, and clinical associations/risk factors of sleep disturbance in primary brain tumour (PBT) survivors and their caregivers; and (2) determine whether there are any sleep-focused interventons reported in the literature pertaining to people affected by PBT. METHODS: This systematic review was registered with the international register for systematic reviews (PROSPERO: CRD42022299332). PubMed, EMBASE, Scopus, PsychINFO, and CINAHL were electronically searched for relevant articles reporting sleep disturbance and/or interventions for managing sleep disturbance published between September 2015 and May 2022. The search strategy included terms focusing on sleep disturbance, primary brain tumours, caregivers of PBT survivors, and interventions. Two reviewers conducted the quality appraisal (JBI Critical Appraisal Tools) independently, with results compared upon completion. RESULTS: 34 manuscripts were eligible for inclusion. Sleep disturbance was highly prevalent in PBT survivors with associations between sleep disturbance and some treatments (e.g., surgical resection, radiotherapy, corticosteroid use), as well as other prevalent symptoms (e.g., fatigue, drowsiness, stress, pain). While the current review was unable to find any sleep-targeted interventions, preliminary evidence suggests physical activity may elicit beneficial change on subjectively reported sleep disturbance in PBT survivors. Only one manuscript that discussed caregivers sleep disturbance was identified. CONCLUSIONS: Sleep disturbance is a prevalent symptom experienced by PBT survivors, yet there is a distinct lack of sleep-focused interventions in this population. This includes a need for future research to include caregivers, with only one study identified. Future research exploring interventions directly focused on the management of sleep disturbance in the context of PBT is warranted.

Physical Activity Alters Functional Connectivity of Orbitofrontal Cortex Subdivisions in Healthy Young Adults: A Longitudinal fMRI Study.

Physical activity (PA) plays an important role in affect processing. Studies describe the orbitofrontal cortex (OFC) as a major hub for emotion processing and the pathophysiology of affective disorders. Subregions of the OFC show diverse functional connectivity (FC) topographies, but the effect of chronic PA on subregional OFC FC still lacks scientific understanding. Therefore, we aimed at investigating the effects of regular PA on the FC topographies of OFC subregions in healthy individuals within a longitudinal randomized controlled exercise study. Participants (age: 18-35 years) were randomly assigned to either an intervention group (IG; N = 18) or a control group (CG; N = 10). Fitness assessments, mood questionnaires, and resting state functional magnetic resonance imaging (rsfMRI) were performed four times over the duration of 6 months. Using a detailed parcellation of the OFC, we created subregional FC topography maps at each time point and applied a linear mixed model to assess the effects of regular PA. The posterior-lateral right OFC showed a group and time interaction, revealing decreased FC with the left dorsolateral prefrontal cortex in the IG, while FC in the CG increased. Group and time interaction in the anterior-lateral right OFC with the right middle frontal gyrus was driven by increased FC in the IG. The posterior-lateral left OFC showed a group and time interaction based on differential change in FC to the left postcentral gyrus and the right occipital gyrus. This study emphasized regionally distinctive FC changes induced by PA within the lateral OFC territory, while providing aspects for further research.

How Virtual Animal Anatomy facilitated a successful transition to online instruction and supported student learning during the coronavirus pandemic.

Anatomy faculty with cadaver-based laboratory courses were presented with a significant challenge in March 2020 to create equivalent learning experiences without cadaveric access. The undergraduate domestic animal anatomy course at the Colorado State University was halfway into a 16-week semester when COVID-19 lockdown orders and the transition to remote instruction began. The new course curriculum was critically evaluated using student surveys and course outcome data. Most students (92.5%) agreed that the transition to online learning was a success; however, students who valued face-to-face lectures prior to March were less likely to perceive the transition as a success. Qualitative and quantitative analyses of survey results suggest that the resources perceived as most helpful for the transition to online learning were not the same as those that helped facilitate animal anatomy learning. Most students (92.5%) agreed that the Virtual Animal Anatomy (VAA) helped them learn anatomy, and 82.2% indicated that the VAA was a valuable resource following the transition to online learning. Additional resources associated with transition success included course instructors, weekly quizzes, written descriptions of anatomical structures and open laboratory sessions. In contrast, those resources associated with facilitating learning included guided quizzes and asynchronous lecture recordings. These findings suggest that the VAA can support online anatomy learning when used in conjunction with other best practices for online teaching.

Osteoradionecrosis of the lamina papyracea leading to recurrent orbital infections-A case study.

Osteoradionecrosis (ORN) is a well-known complication of radiotherapy (RT) to the sino-nasal cavity and nasopharynx. Here, we report a case of recurrent orbital infections secondary to ORN of the lamina papyracea (LP). A 66-year-old female presented to our unit with right periorbital swelling and pain after having undergone chemotherapy and proton beam irradiation to her ethmoid sinuses for sino-nasal undifferentiated carcinoma (SNUC) 5 years prior. She had also undergone endoscopic sinus surgery for chronic rhinosinusitis about a year prior to the current presentation. Her post-operative course was notable for recurrent episodes of pre-septal cellulitis occurring about 3 months apart that were increasingly severe. Examination revealed right proptosis, and endoscopy showed an exposed and denuded LP with scant crusting of the ethmoid sinuses. Microbial studies did not yield any significant growth, and imaging showed enhancement of the right orbit. The working diagnosis was acute right orbital cellulitis secondary to ORN of the right LP. She was treated with broad spectrum intravenous antibiotics and systemic steroids, but experienced minimal symptomatic improvement. She then underwent endoscopic resection of the right LP, and histopathological examination showed osteonecrosis on an inflammatory background. Post-operatively, all orbital symptoms resolved and she was well at 6 months' follow up. In the discussion, we highlight additional factors in our patient that may have contributed to this clinical presentation, and hope that this report raises awareness of a rare complication of RT to the sino-nasal cavity.

OpenFL: the open federated learning library.

Objective.Federated learning (FL) is a computational paradigm that enables organizations to collaborate on machine learning (ML) and deep learning (DL) projects without sharing sensitive data, such as patient records, financial data, or classified secrets.Approach.Open federated learning (OpenFL) framework is an open-source python-based tool for training ML/DL algorithms using the data-private collaborative learning paradigm of FL, irrespective of the use case. OpenFL works with training pipelines built with both TensorFlow and PyTorch, and can be easily extended to other ML and DL frameworks.Main results.In this manuscript, we present OpenFL and summarize its motivation and development characteristics, with the intention of facilitating its application to existing ML/DL model training in a production environment. We further provide recommendations to secure a federation using trusted execution environments to ensure explicit model security and integrity, as well as maintain data confidentiality. Finally, we describe the first real-world healthcare federations that use the OpenFL library, and highlight how it can be applied to other non-healthcare use cases.Significance.The OpenFL library is designed for real world scalability, trusted execution, and also prioritizes easy migration of centralized ML models into a federated training pipeline. Although OpenFL's initial use case was in healthcare, it is applicable beyond this domain and is now reaching wider adoption both in research and production settings. The tool is open-sourced atgithub.com/intel/openfl.

The federated tumor segmentation (FeTS) tool: an open-source solution to further solid tumor research.

Objective.De-centralized data analysis becomes an increasingly preferred option in the healthcare domain, as it alleviates the need for sharing primary patient data across collaborating institutions. This highlights the need for consistent harmonized data curation, pre-processing, and identification of regions of interest based on uniform criteria.Approach.Towards this end, this manuscript describes theFederatedTumorSegmentation (FeTS) tool, in terms of software architecture and functionality.Main results.The primary aim of the FeTS tool is to facilitate this harmonized processing and the generation of gold standard reference labels for tumor sub-compartments on brain magnetic resonance imaging, and further enable federated training of a tumor sub-compartment delineation model across numerous sites distributed across the globe, without the need to share patient data.Significance.Building upon existing open-source tools such as the Insight Toolkit and Qt, the FeTS tool is designed to enable training deep learning models targeting tumor delineation in either centralized or federated settings. The target audience of the FeTS tool is primarily the computational researcher interested in developing federated learning models, and interested in joining a global federation towards this effort. The tool is open sourced athttps://github.com/FETS-AI/Front-End.

Regional cortical perfusion increases induced by a 6-month endurance training in young sedentary adults.

Physical inactivity is documented as a health risk factor for chronic diseases, accelerated aging, and cognitive impairment. Physical exercise, on the other hand, plays an important role in healthy aging by promoting positive muscular, cardiovascular, and central nervous system adaptions. Prior studies on the effects of exercise training on cerebral perfusion have focused largely on elderly cohorts or patient cohorts, while perfusion effects of exercise training in young sedentary adults have not yet been fully assessed. Therefore, the present study examined the physiological consequence of a 6-month endurance exercise training on brain perfusion in 28 young sedentary adults randomly assigned to an intervention group (IG; regular physical exercise) or a control group (CG; without physical exercise). The IG performed an extensive running interval training three times per week over 6 months. Performance diagnostics and MRI were performed every 2 months, and training intensity was adapted individually. Brain perfusion measurements with pseudo-continuous arterial spin labeling were analyzed using the standard Oxford ASL pipeline. A significant interaction effect between group and time was found for right superior temporal gyrus (STG) perfusion, driven by an increase in the IG and a decrease in the CG. Furthermore, a significant time effect was observed in the right middle occipital region in the IG only. Perfusion increases in the right STG, in the ventral striatum, and in primary motor areas were significantly associated with increases in maximum oxygen uptake (VO2max). Overall, this study identified region-specific increases in local perfusion in a cohort of young adults that partly correlated with individual performance increases, hence, suggesting exercise dose dependency. Respective adaptations in brain perfusion are discussed in the context of physical exercise-induced vascular plasticity.

Variation within the visually evoked neurovascular coupling response of the posterior cerebral artery is not influenced by age or sex.

Neurovascular coupling (NVC) is the temporal and spatial coordination between local neuronal activity and regional cerebral blood flow. The literature is unsettled on whether age and/or sex affect NVC, which may relate to differences in methodology and the quantification of NVC in small sample-sized studies. The aim of this study was to 1) determine the relative and combined contribution of age and sex to the variation observed across several distinct NVC metrics (n = 125, 21-66 yr; 41 males) and 2) present an approach for the comprehensive systematic assessment of the NVC response using transcranial Doppler ultrasound. NVC was measured as the relative change from baseline (absolute and percent change) assessing peak, mean, and total area under the curve (tAUC) of cerebral blood velocity through the posterior cerebral artery (PCAv) during intermittent photic stimulation. In addition, the NVC waveform was compartmentalized into distinct regions, acute (0-9 s), mid (10-19 s), and late (20-30 s), following the onset of photic stimulation. Hierarchical multiple regression modeling was used to determine the extent of variation within each NVC metric attributable to demographic differences in age and sex. After controlling for differences in baseline PCAv, the R2 data suggest that 1.6%, 6.1%, 1.1%, 3.4%, 2.5%, and 4.2% of the variance observed within mean, peak, tAUC, acute, mid, and late response magnitude is attributable to the combination of age and sex. Our study reveals that variability in NVC response magnitude is independent of age and sex in healthy human participants, aged 21-66 yr.NEW & NOTEWORTHY We assessed the variability within the neurovascular coupling response attributable to age and sex (n = 125, 21-66 yr; 41 male). Based on the assessment of posterior cerebral artery responses to visual stimulation, 0%-6% of the variance observed within several metrics of NVC response magnitude are attributable to the combination of age and sex. Therefore, observed differences between age groups and/or sexes are likely a result of other physiological factors.

Effects of a 6-Month Aerobic Exercise Intervention on Mood and Amygdala Functional Plasticity in Young Untrained Subjects.

Acute exercise has beneficial effects on mood and is known to induce modulations in functional connectivity (FC) within the emotional network. However, the long-term effects of exercise on affective brain circuits remain largely unknown. Here, we investigated the effects of 6 months of regular exercise on mood, amygdala structure, and functional connectivity. This study comprised N = 18 healthy sedentary subjects assigned to an intervention group (IG; 23.9 ± 3.9 years; 3 trainings/week) and N = 10 subjects assigned to a passive control group (CG; 23.7 ± 4.2 years). At baseline and every two months, performance diagnostics, mood questionnaires, and structural and resting-state-fMRI were conducted. Amygdala-nuclei segmentation and amygdala-to-whole-brain FC analysis were performed. Linear mixed effects models and correlation analyses were conducted between FC, relVO2max, and mood scores. Data showed increases in relVO2max exclusively in the IG. Stronger anticorrelation in amygdala-precuneus FC was found, along with a stronger positive correlation in the amygdala-temporal pole FC in the IG after 4 and 6 months, while mood and amygdala volume did not reveal significant interactions. The relVO2max/amygdala-temporal pole FC correlated positively, and the amygdala-precuneus/amygdala-temporal pole FC correlated negatively. Findings suggest that exercise induced long-term modulations of the amygdala FC with the precuneus and temporal pole, shedding light on potential mechanisms by which exercise has positive influences on mood-related networks, typically altered in affective disorders.

A phase I randomized, double-blind, placebo-controlled study to evaluate the safety, tolerability, and immunogenicity of a live-attenuated quadrivalent dengue vaccine in flavivirus-naïve and flavivirus-experienced healthy adults.

Dengue (DENV) is a mosquito-borne virus with four serotypes causing substantial morbidity in tropical and subtropical areas worldwide. V181 is an investigational, live, attenuated, quadrivalent dengue vaccine. In this phase 1 double-blind, placebo-controlled study, the safety, tolerability, and immunogenicity of V181 in baseline flavivirus-naïve (BFN) and flavivirus-experienced (BFE) healthy adults were evaluated in two formulations: TV003 and TV005. TV005 contains a 10-fold higher DENV2 level than TV003. Two-hundred adults were randomized 2:2:1 to receive TV003, TV005, or placebo on Days 1 and 180. Immunogenicity against the 4 DENV serotypes was measured using a Virus Reduction Neutralization Test (VRNT60) after each vaccination and out to 1 year after the second dose. There were no discontinuations due to adverse events (AE) or serious vaccine-related AEs in the study. Most common AEs after TV003 or TV005 were headache, rash, fatigue, and myalgia. Tri- or tetravalent vaccine-viremia was detected in 63.9% and 25.6% of BFN TV003 and TV005 participants, respectively, post-dose 1 (PD1). Tri- or tetravalent dengue VRNT60 seropositivity was demonstrated in 92.6% of BFN TV003, 74.2% of BFN TV005, and 100% of BFE TV003 and TV005 participants PD1. Increases in VRNT60 GMTs were observed after the first vaccination with TV003 and TV005 in both flavivirus subgroups for all dengue serotypes, and minimal increases were measured PD2. GMTs in the TV003 and TV005 BFE and BFN groups remained above the respective baselines and placebo through 1-year PD2. These data support further development of V181 as a single-dose vaccine for the prevention of dengue disease.

Enhancing Anatomical Instruction: Impact of a Virtual Canine Anatomy Program on Student Outcomes.

Innovative reforms in medical education will require instructional tools to support these changes and to give students more flexibility in where and how they learn. At Colorado State University, the software program Virtual Canine Anatomy (VCA) was developed to assist student learning both inside and outside the anatomical laboratory. The program includes interactive anatomical photographs of dissected canine cadavers, dissection instructions with accompanying videos and diagrams, radiographs, and three-dimensional models. There is a need to evaluate the effectiveness of instructional tools like VCA so that decisions on pedagogical delivery can be evidence-based. To measure the impact of VCA on student outcomes in a dissection laboratory, this study compared student attitudes, quiz scores, dissection quality and accuracy, and instructor reliance between students with and without access to VCA. Students with VCA needed less time with teaching assistants (P < 0.01), asked teaching assistants fewer questions (P = 0.04), felt that the dissection was easier (P = 0.02), and were in stronger agreement that they had access to adequate resources (P = 0.02). No differences were found in the dissection quality or accuracy, quiz scores, or attitudes regarding overall enjoyment of the activity between the two groups. This study shows that VCA increases student independence and can be used to enhance anatomical instruction.

Investigating causality with fecal microbiota transplantation in rodents: applications, recommendations and pitfalls.

In recent years, studies investigating the role of the gut microbiota in health and diseases have increased enormously - making it essential to deepen and question the research methodology employed. Fecal microbiota transplantation (FMT) in rodent studies (either from human or animal donors) allows us to better understand the causal role of the intestinal microbiota across multiple fields. However, this technique lacks standardization and requires careful experimental design in order to obtain optimal results. By comparing several studies in which rodents are the final recipients of FMT, we summarize the common practices employed. In this review, we document the limitations of this method and highlight different parameters to be considered while designing FMT Studies. Standardizing this method is challenging, as it differs according to the research topic, but avoiding common pitfalls is feasible. Several methodological questions remain unanswered to this day and we offer a discussion on issues to be explored in future studies.

Sequential administration of Prevnar 13™ and PNEUMOVAX™ 23 in healthy participants 50 years of age and older.

In most countries worldwide, pneumococcal conjugate vaccines have been included in the infant immunization program, resulting in a significant reduction in the burden of pneumococcal disease in children and adults. Shifting serotype distribution due to the indirect effect of infant vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) may continue to increase the gap between 23-valent pneumococcal polysaccharide vaccine (PPSV23) and PCV13 serotype coverage for older adults in the coming years. This clinical study (V110-029; NCT02225587) evaluated the safety and immunogenicity of sequential administration of PCV13 followed approximately 8 weeks later, or approximately 26 weeks later, by PPSV23 in healthy adults ≥50 years of age. Both dosing intervals were generally well tolerated as measured by the nature, frequency, and intensity of reported adverse events (AEs) in both vaccination groups. Serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) measured 30 days following receipt of PPSV23 in either group and at Week 30 were generally comparable between the 2 groups for 6 serotypes unique to PPSV23 and 12 serotypes shared between PCV13 and PPSV23, regardless of the interval between receipt of PCV13 and PPSV23. In addition, administration of PPSV23 given either 8 weeks or 26 weeks following PCV13 did not negatively impact immune responses induced by PCV13. Furthermore, administration of PPSV23 given either 8 weeks or 26 weeks after PCV13 elicited serotype-specific OPA GMTs to serotypes unique to PPSV23, which could provide earlier protection against pneumococcal disease caused by these serotypes in comparison with the current Advisory Committee on Immunization Practices recommended interval of at least 12 months.

Natural variation in colony inbreeding does not influence susceptibility to a fungal pathogen in a termite.

Reduced genetic diversity through inbreeding can negatively affect pathogen resistance. This relationship becomes more complicated in social species, such as social insects, since the chance of disease transmission increases with the frequency of interactions among individuals. However, social insects may benefit from social immunity, whereby individual physiological defenses may be bolstered by collective-level immune responses, such as grooming or sharing of antimicrobial substance through trophallaxis. We set out to determine whether differences in genetic diversity between colonies of the subterranean termite, Reticulitermes flavipes, accounts for colony survival against pathogens. We sampled colonies throughout the United States (Texas, North Carolina, Maryland, and Massachusetts) and determined the level of inbreeding of each colony. To assess whether genetically diverse colonies were better able to survive exposure to diverse pathogens, we challenged groups of termite workers with two strains of a pathogenic fungus, one local strain present in the soil surrounding sampled colonies and another naïve strain, collected outside the range of this species. We found natural variation in the level of inbreeding between colonies, but this variation did not explain differences in susceptibility to either pathogen. Although the naïve strain was found to be more hazardous than the local strain, colony resistance was correlated between two strains, meaning that colonies had either relatively high or low susceptibility to both strains regardless of their inbreeding coefficient. Overall, our findings may reflect differential virulence between the strains, immune priming of the colonies via prior exposure to the local strain, or a coevolved resistance toward this strain. They also suggest that colony survival may rely more upon additional factors, such as different behavioral response thresholds or the influence of a specific genetic background, rather than the overall genetic diversity of the colony.

Using the power law model to predict the long-term persistence and duration of detectable hepatitis A antibody after receipt of hepatitis A vaccine (VAQTA™).

VAQTA™ (Hepatitis A Vaccine, inactivated [HAVi]; Merck & Co., Inc., Kenilworth, NJ, USA) is currently licensed for prevention of disease caused by hepatitis A virus in persons ≥12 months of age. This report summarizes statistical models developed to evaluate the long-term persistence and duration of detectable hepatitis A antibody (total antibody levels with no distinction on class) after receipt of HAVi in healthy children and adolescents (V251-023 and V251-035) and in healthy adults (V251-034). The statistical models presented, conducted separately for each of the three studies, are based on models that have been used in the literature to estimate the duration of antibody to protect against human papillomavirus (HPV) disease. In the absence of observed study data on hepatitis A antibody persistence for vaccine recipients over several decades, an extrapolation from a kinetic model of antibody decay was used to estimate the duration of detectable antibody. Extrapolation of observed antibody titers from postvaccination, Year 2.5-3.5, Year 5-6, and Year 10 in 165 children and adolescents who received HAVi at Day 0 and Week 24 in V251-023 suggests that detectable levels of antibody may persist after the second dose for many years. This model suggests that 25 to 50 years Postdose 1 in a two-dose series of HAVi, 99.4% of the study population will have detectable levels of hepatitis A antibody.

A Simple Tool for Recommending Postoperative Status After Lower Extremity Total Joint Replacement.

There is an increasing impetus to perform primary total hip arthroplasty and total knee arthroplasty on an outpatient basis and in the outpatient setting. However, with recent federal regulatory changes, orthopedic surgeons must now evaluate patients on a case-by-case basis to determine whether an inpatient admission will be medically necessary and appropriate. We thus created our prototype Lower Extremity Inpatient-Outpatient (LET-IN-OUT) total joint replacement tool as a simple, consistent way for other clinicians to identify specific major preoperative patient comorbidities and thus to recommend independently and objectively to the orthopedic surgeon postoperative inpatient or outpatient status for a given patient.

The effect of exercise interventions on inflammatory markers in major depressive disorder: protocol for a systematic review and meta-analysis.

Background: Depression currently affects 4.4% of the global population, and 93.7% of this population suffer from major depressive disorder (MDD) according to 2017 statistics. MDD patients are more likely to suffer from co-morbidities such as cardiovascular disease and high body mass index (BMI), thus contributing to its large cost to society. Throughout the literature, there are known links between inflammation and MDD. Interestingly, while exercise is considered a promising intervention for MDD, the mechanism(s) of action remain unclear, thereby preventing the creation of optimal, cost-saving, exercise "prescriptions" for those with MDD. Thus, the aim of this review and meta-analysis is to summarize and analyse the current literature exploring how quantified exercise interventions modulate inflammatory molecules in MDD patients. Methods: Electronic databases (APA PsycINFO, and PubMed/MEDLINE (EBSCO interface), EMBASE) will be searched using a detailed search strategy comprised of three search term themes: exercise, depression/MDD, and inflammation/inflammatory molecules. Only quantified exercise interventions performed in adult humans with MDD validated via a recognized diagnostic criterion will be included. Studies should also include a MDD control group and explore changes in inflammatory molecules. Examples of these molecules include: C-reactive protein (CRP), interleukin-6 (IL-6), interleukin-1 beta (IL-1b), tumour necrosis factor-alpha (TNF-a), homocysteine, d-dimer and myeloperoxidase (MPO). After eligible studies are identified, standardized data extraction will be employed and the risk of bias in each study will be appraised using the Cochrane handbook checklists. In the event of two or more homogenous studies exploring exercise effects over a similar time period, raw mean differences or standardized mean differences will be pooled using random effects analysis. This systematic review and meta-analysis will be reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Dissemination: This systematic review and meta-analysis will be disseminated in peer-reviewed journals. PROSPERO registration: CRD42020186006 (31/08/2020).

Quantitation of uridine and L-dihydroorotic acid in human plasma by LC-MS/MS using a surrogate matrix approach.

Uridine and L-dihydroorotate (DHO) are important intermediates of de novo as well as salvage pathways for the biosynthesis of pyrimidines, which are the building blocks of nucleic acids - DNA and RNA. These metabolites are known to be significant biomarkers of pyrimidine synthesis during the development of DHODH inhibitor drugs for treatment of several cancers and immunological disorders. Here we are reporting a validated LC-MS/MS assay for the quantitation of uridine and DHO in K2EDTA human plasma. Due to presence of endogenous uridine and DHO in the biological matrix, a surrogate matrix approach with bovine serum albumin (BSA) solution was used. Human plasma samples were spiked with stable isotope labeled internal standards, processed by protein precipitation, and analyzed using LC-MS/MS. Parallelism was successfully demonstrated between human plasma (the authentic matrix) and BSA (the surrogate matrix). The linear analytical ranges of the assay were set at 30.0-30,000 ng/mL for uridine and 3.00-3,000 ng/mL for DHO. This validated LC-MS/MS method demonstrated excellent accuracy and precision. The overall accuracy was between 91.9 % and 106 %, and the inter-assay precision (%CV) were less than 4.2 % for uridine in human plasma. The overall accuracy was between 92.8 % and 106 %, and the inter-assay precision (%CV) were less than 7.2 % for DHO in human plasma. Uridine and DHO were found to be stable in human plasma for at least 24 h at room temperature, 579 days when stored at -20 °C, 334 days when stored at -70 °C, and after five freeze/thaw cycles. The assay has been successfully applied to human plasma samples to support clinical studies. Novel Aspect: A surrogate matrix approach to quantify endogenous uridine and DHO concentrations in human plasma.

Aß40 displays amyloidogenic properties in the non-transgenic mouse brain but does not exacerbate Aß42 toxicity in Drosophila.

BACKGROUND: Self-assembly of the amyloid-ß (Aß) peptide into aggregates, from small oligomers to amyloid fibrils, is fundamentally linked with Alzheimer's disease (AD). However, it is clear that not all forms of Aß are equally harmful and that linking a specific aggregate to toxicity also depends on the assays and model systems used (Haass et al., J Biol. Chem 269:17741-17748, 1994; Borchelt et al., Neuron 17:1005-1013, 1996). Though a central postulate of the amyloid cascade hypothesis, there remain many gaps in our understanding regarding the links between Aß deposition and neurodegeneration. METHODS: In this study, we examined familial mutations of Aß that increase aggregation and oligomerization, E22G and ΔE22, and induce cerebral amyloid angiopathy, E22Q and D23N. We also investigated synthetic mutations that stabilize dimerization, S26C, and a phospho-mimetic, S8E, and non-phospho-mimetic, S8A. To that end, we utilized BRI2-Aß fusion technology and rAAV2/1-based somatic brain transgenesis in mice to selectively express individual mutant Aß species in vivo. In parallel, we generated PhiC31-based transgenic Drosophila melanogaster expressing wild-type (WT) and Aß40 and Aß42 mutants, fused to the Argos signal peptide to assess the extent of Aß42-induced toxicity as well as to interrogate the combined effect of different Aß40 and Aß42 species. RESULTS: When expressed in the mouse brain for 6 months, Aß42 E22G, Aß42 E22Q/D23N, and Aß42WT formed amyloid aggregates consisting of some diffuse material as well as cored plaques, whereas other mutants formed predominantly diffuse amyloid deposits. Moreover, while Aß40WT showed no distinctive phenotype, Aß40 E22G and E22Q/D23N formed unique aggregates that accumulated in mouse brains. This is the first evidence that mutant Aß40 overexpression leads to deposition under certain conditions. Interestingly, we found that mutant Aß42 E22G, E22Q, and S26C, but not Aß40, were toxic to the eye of Drosophila. In contrast, flies expressing a copy of Aß40 (WT or mutants), in addition to Aß42WT, showed improved phenotypes, suggesting possible protective qualities for Aß40. CONCLUSIONS: These studies suggest that while some Aß40 mutants form unique amyloid aggregates in mouse brains, they do not exacerbate Aß42 toxicity in Drosophila, which highlights the significance of using different systems for a better understanding of AD pathogenicity and more accurate screening for new potential therapies.