Weakness Status is Differentially Associated with Time to Diabetes in Americans.

Background: The purpose of this study was to evaluate the associations of (1) individual absolute and body size normalized weakness cut-points, and (2) the collective weakness classifications on time to diabetes in Americans. Methods: We analyzed data from 9577 adults aged at least 50-years from the Health and Retirement Study. Diabetes diagnosis was self-reported. A handgrip dynamometer measured handgrip strength (HGS). Males with HGS <35.5 kg (absolute), <0.45 kg/kg (normalized to body weight), or <1.05 kg/kg/m2 (normalized to BMI) were categorized as weak. Females were classified as weak if their HGS was <20.0 kg, <0.337 kg/kg, or <0.79 kg/kg/m2. Compounding weakness included falling below 1, 2, or all 3 cut-points. Results: Persons below the body weight normalized weakness cut-points had a 1.29 (95% confidence interval (CI): 1.15-1.47) higher hazard for incident diabetes, while those below the BMI normalized cut-points had a 1.30 (CI: 1.13-1.51) higher hazard. The association between absolute weakness and incident diabetes was insignificant (hazard ratio: 1.06; CI: 0.91-1.24). Americans below 1, 2, or all 3 collective weakness categories had a 1.28 (CI: 1.10-1.50), 1.29 (CI: 1.08-1.52), and 1.33 (CI: 1.09-1.63) higher hazard for the incidence of diabetes, respectively. Conclusions: Our findings indicate that while absolute weakness, which is confounded by body size, was not associated with time to diabetes, adjusting for the influence of body size by normalizing HGS to body weight and BMI was significantly associated with time to diabetes. This suggests that muscle strength, not body size, may be driving such associations with time to diabetes.

Activity levels across the intensity spectrum in athletes: a systematic review protocol.

Physical activity (PA) promotes better cardiometabolic health, physical function, brain health and longevity. In contrast, prolonged sedentary behaviour (SB) is a risk factor for many chronic diseases and poor health. Limited research has evaluated or synthesised how competitive sports participation influences PA across the lifespan. Some evidence suggests, ironically, that former competitive athletes may be insufficiently active and current athletes may be highly sedentary away from sport. This study describes the protocol for a systematic review and meta-analysis on activity levels across the intensity spectrum in athletes, addressing the primary research question: is sports participation significantly associated with PA and/or SB among current and former competitive athletes? PubMed, Embase, Cochrane Database of Systematic Reviews, Web of Science and SPORTDiscus databases will be searched. Two reviewers will independently screen titles/abstracts and full texts of selected abstracts. Data will be extracted regarding the study population, sport played, PA measures and protocols, outcomes of interest and findings. Primary outcomes will include step counts, daily activity across the intensity spectrum (ie, sedentary, light, moderate and vigorous PA), metabolic equivalent of task and whole-day energy expenditure. Secondary outcomes will include additional accelerometry measures of PA, activity patterns and self-reported PA. The risk of bias will be assessed using the National Institutes of Health Study Quality Assessment Tools. Extracted data will be presented using narrative synthesis and tabular presentation. Meta-analyses will be conducted to determine outcomes with sufficient data.PROSPERO registration number: CRD42024469267.https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=469267.

Discovery of an embryonically derived bipotent population of endothelial-macrophage progenitor cells in postnatal aorta.

Converging evidence indicates that extra-embryonic yolk sac is the source of both macrophages and endothelial cells in adult mouse tissues. Prevailing views are that these embryonically derived cells are maintained after birth by proliferative self-renewal in their differentiated states. Here we identify clonogenic endothelial-macrophage (EndoMac) progenitor cells in the adventitia of embryonic and postnatal mouse aorta, that are independent of Flt3-mediated bone marrow hematopoiesis and derive from an early embryonic CX3CR1+ and CSF1R+ source. These bipotent progenitors are proliferative and vasculogenic, contributing to adventitial neovascularization and formation of perfused blood vessels after transfer into ischemic tissue. We establish a regulatory role for angiotensin II, which enhances their clonogenic and differentiation properties and rapidly stimulates their proliferative expansion in vivo. Our findings demonstrate that embryonically derived EndoMac progenitors participate in local vasculogenic responses in the aortic wall by contributing to the expansion of endothelial cells and macrophages postnatally.

Single-cell spatial transcriptomics reveals distinct patterns of dysregulation in non-neuronal and neuronal cells induced by the Trem2R47H Alzheimer's risk gene mutation.

The R47H missense mutation of the TREM2 gene is a known risk factor for development of Alzheimer's Disease. In this study, we analyze the impact of the Trem2R47H mutation on specific cell types in multiple cortical and subcortical brain regions in the context of wild-type and 5xFAD mouse background. We profile 19 mouse brain sections consisting of wild-type, Trem2R47H, 5xFAD and Trem2R47H; 5xFAD genotypes using MERFISH spatial transcriptomics, a technique that enables subcellular profiling of spatial gene expression. Spatial transcriptomics and neuropathology data are analyzed using our custom pipeline to identify plaque and Trem2R47H-induced transcriptomic dysregulation. We initially analyze cell type-specific transcriptomic alterations induced by plaque proximity. Next, we analyze spatial distributions of disease associated microglia and astrocytes, and how they vary between 5xFAD and Trem2R47H; 5xFAD mouse models. Finally, we analyze the impact of the Trem2R47H mutation on neuronal transcriptomes. The Trem2R47H mutation induces consistent upregulation of Bdnf and Ntrk2 across many cortical excitatory neuron types, independent of amyloid pathology. Spatial investigation of genotype enriched subclusters identified spatially localized neuronal subpopulations reduced in 5xFAD and Trem2R47H; 5xFAD mice. Overall, our MERFISH spatial transcriptomics analysis identifies glial and neuronal transcriptomic alterations induced independently by 5xFAD and Trem2R47H mutations, impacting inflammatory responses in microglia and astrocytes, and activity and BDNF signaling in neurons.

Factors affecting advance care planning in older adults with cancer.

INTRODUCTION: Advance care planning (ACP) has been widely endorsed and recommended for its many potential benefits, including improved end-of-life (EOL) care, enhanced satisfaction with care, and reduced anxiety and depression. However, little is known about the ACP completion rates and factors affecting ACP among older adults with cancer. This study's purpose was to examine biological, psychological, and social factors affecting ACP in this population. MATERIALS AND METHODS: Data from the 2002 to 2016 waves of exit interviews from the national longitudinal Health and Retirement Study were analyzed. The sample included 1088 decedents, aged 55 and over, who had a diagnosis of cancer. The exit interviews were completed by a proxy respondent (usually the next of kin of the decedents). ACP outcomes included: having EOL care discussion, durable power of attorney (DPOA), and advance directives (ADs). Multiple logistic regression models were conducted to examine the relationships between predictor variables and each of the three ACP outcome variables. RESULTS: Approximately 65% of the sample had ever discussed EOL care, 61.9% had an assigned DPOA, and 54.1% had ADs. Regression results showed that higher age, Black race, high school and above education, being widowed/never married, higher multimorbidity, and more limitations in activities of daily living and instrumental activities of daily living were significantly associated with the three ACP variables. Surprisingly, Black race was associated with higher odds of ever discussing EOL care and having ADs; high school and above education was associated with lower odds of all three ACP components. DISCUSSION: The majority of participants in this study had discussed EOL care, had an assigned DPOA, and had ADs. However, most participants were White/Caucasian and had completed high school education. Future research that includes more diverse and minoritized participants is needed. Also, the contrasting association of Black race and higher educational status with ACP outcomes warrant further exploration in future studies.

Can Periprosthetic Joint Infection of Tumor Prostheses Be Controlled With Debridement, Antibiotics, and Implant Retention?

BACKGROUND: Two-stage revision for periprosthetic joint infection (PJI) in patients who have undergone segmental replacement of the distal femur or proximal tibia after tumor resection can be associated with considerable morbidity, pain, and risk of complications because the procedure often results in removal of long, well-fixed stems from the diaphysis. A less-aggressive surgical approach, such as debridement, antibiotics, and implant retention (DAIR), may be attractive to patients and surgeons because of less morbidity, but the likelihood of eradicating infection in comparison to the traditional two-stage revision is not well established for oncology patients. Furthermore, the relative risk of subsequent amputation for DAIR versus two-stage revision has not been defined for this population. QUESTIONS/PURPOSES: (1) How does DAIR compare with two-stage revision in terms of infection control for patients with distal femoral or proximal tibial segmental modular endoprostheses? (2) Is DAIR as an initial procedure associated with an increased risk of amputation compared with two-stage revision for infection? METHODS: From the longitudinally maintained orthopaedic oncology surgical database at our institution, we identified 69 patients who had been treated for a clinical diagnosis of PJI at the knee between 1993 and 2015. We excluded 32% (22) of patients who did not meet at least one of the major criteria of the Musculoskeletal Infection Society (MSIS) for PJI, 3% (2) of patients who underwent immediate amputation, 3% (2) of patients who had a follow-up time of < 24 months, and 7% (5) of patients who did not have a primary tumor of the distal femur or proximal tibia. The study consisted of 38 patients, of whom eight underwent two-stage revision, 26 underwent DAIR, and four underwent extended DAIR (removal of all segmental components but with retention of stems and components fixed in bone) for their initial surgical procedure. To be considered free of infection, patients had to meet MSIS standards, including no positive cultures, drainage, or surgical debridement for a minimum of 2 years from the last operation. Factors associated with time-dependent risk of infection relapse, clearance, amputation, and patient survival were analyzed using Kaplan-Meier survivorship curves and the log-rank test to compare factors. Association of demographic and treatment factors was assessed using chi-square and Fisher exact tests. RESULTS: Continuous infection-free survival at 5 years was 16% (95% CI 2% to 29%) for patients undergoing DAIR compared with 75% (95% CI 45% to 100%) for patients undergoing two-stage revision (p = 0.006). The median (range) number of total surgical procedures was 3 per patient (1 to 10) for DAIR and 2 (2 to 5) for two-stage revision. Twenty-nine percent (11 of 38) of patients eventually underwent amputation. Survival without amputation was 69% (95% CI 51% to 86%) for DAIR compared with 88% (95% CI 65% to 100%) for two-stage revision at 5 years (p = 0.34). The cumulative proportion of patients achieving infection-free status (> 2 years continuously after last treatment) and limb preservation was 58% (95% CI 36% to 80%) for patients initially treated with DAIR versus 87% (95% CI 65% to 100%) for patients first treated with two-stage revision (p = 0.001). CONCLUSION: Infection control was better with two-stage revision than DAIR. The chance of eventual clearance of infection with limb preservation was better when two-stage revision was chosen as the initial treatment. However, the loss to follow-up in the two-stage revision group would likely make the true proportion of infection control lower than our estimate. Our experience would suggest that the process of infection eradication is a complex and difficult one. Most patients undergo multiple operations. Nearly one-third of patients eventually underwent amputation, and this was a serious risk for both groups. While we cannot strongly recommend one approach over the other based on our data, we would still consider the use of DAIR in patients who present with acute short duration of symptoms (< 3 weeks), no radiographic signs of erosion around fixed implants, and organisms other than Staphylococcus aureus. We would advocate the extended DAIR procedure with removal of all segmental or modular components, and we would caution patients that there is a high likelihood of needing further surgery. A prospective trial with strict adherence to indications may be needed to evaluate the relative merits of an extended DAIR procedure versus a two-stage revision. LEVEL OF EVIDENCE: Level III, therapeutic study.

Depletion of follicular B cell-derived antibody secreting cells does not attenuate angiotensin II-induced hypertension or vascular compliance.

Introduction: Marginal zone and follicular B cells are known to contribute to the development of angiotensin II-induced hypertension in mice, but the effector function(s) mediating this effect (e.g., antigen presentation, antibody secretion and/or cytokine production) are unknown. B cell differentiation into antibody secreting cells (ASCs) requires the transcription factor Blimp-1. Here, we studied mice with a Blimp-1 deficiency in follicular B cells to evaluate whether antibody secretion underlies the pro-hypertensive action of B cells. Methods: 10- to 14-week-old male follicular B cell Blimp-1 knockout (FoB-Blimp-1-KO) and floxed control mice were subcutaneously infused with angiotensin II (0.7 mg/kg/d) or vehicle (0.1% acetic acid in saline) for 28 days. BP was measured by tail-cuff plethysmography or radiotelemetry. Pulse wave velocity was measured by ultrasound. Aortic collagen was quantified by Masson's trichrome staining. Cell types and serum antibodies were quantified by flow cytometry and a bead-based multiplex assay, respectively. Results: In control mice, angiotensin II modestly increased serum IgG3 levels and markedly increased BP, cardiac hypertrophy, aortic stiffening and fibrosis. FoB-Blimp-1-KO mice exhibited impaired IgG1, IgG2a and IgG3 production despite having comparable numbers of B cells and ASCs to control mice. Nevertheless, FoB-Blimp-1-KO mice still developed hypertension, cardiac hypertrophy, aortic stiffening and fibrosis following angiotensin II infusion. Conclusions: Inhibition of follicular B cell differentiation into ASCs did not protect against angiotensin II-induced hypertension or vascular compliance. Follicular B cell functions independent of their differentiation into ASCs and ability to produce high-affinity antibodies, or other B cell subtypes, are likely to be involved in angiotensin II-induced hypertension.

Cystatin F attenuates neuroinflammation and demyelination following murine coronavirus infection of the central nervous system.

BACKGROUND: Cystatin F is a secreted lysosomal cysteine protease inhibitor that has been implicated in affecting the severity of demyelination and enhancing remyelination in pre-clinical models of immune-mediated demyelination. How cystatin F impacts neurologic disease severity following viral infection of the central nervous system (CNS) has not been well characterized and was the focus of this study. We used cystatin F null-mutant mice (Cst7-/-) with a well-established model of murine coronavirus-induced neurologic disease to evaluate the contributions of cystatin F in host defense, demyelination and remyelination. METHODS: Wildtype controls and Cst7-/- mice were intracranially (i.c.) infected with a sublethal dose of the neurotropic JHM strain of mouse hepatitis virus (JHMV), with disease progression and survival monitored daily. Viral plaque assays and qPCR were used to assess viral levels in CNS. Immune cell infiltration into the CNS and immune cell activation were determined by flow cytometry and 10X genomics chromium 3' single cell RNA sequencing (scRNA-seq). Spinal cord demyelination was determined by luxol fast blue (LFB) and Hematoxylin/Eosin (H&E) staining and axonal damage assessed by immunohistochemical staining for SMI-32. Remyelination was evaluated by electron microscopy (EM) and calculation of g-ratios. RESULTS: JHMV-infected Cst7-/- mice were able to control viral replication within the CNS, indicating that cystatin F is not essential for an effective Th1 anti-viral immune response. Infiltration of T cells into the spinal cords of JHMV-infected Cst7-/- mice was increased compared to infected controls, and this correlated with increased axonal damage and demyelination associated with impaired remyelination. Single-cell RNA-seq of CD45 + cells enriched from spinal cords of infected Cst7-/- and control mice revealed enhanced expression of transcripts encoding T cell chemoattractants, Cxcl9 and Cxcl10, combined with elevated expression of interferon-g (Ifng) and perforin (Prf1) transcripts in CD8 + T cells from Cst7-/- mice compared to controls. CONCLUSIONS: Cystatin F is not required for immune-mediated control of JHMV replication within the CNS. However, JHMV-infected Cst7-/- mice exhibited more severe clinical disease associated with increased demyelination and impaired remyelination. The increase in disease severity was associated with elevated expression of T cell chemoattractant chemokines, concurrent with increased neuroinflammation. These findings support the idea that cystatin F influences expression of proinflammatory gene expression impacting neuroinflammation, T cell activation and/or glia cell responses ultimately impacting neuroinflammation and neurologic disease.

Impacts of rainfall and rainfall anomalies on the population dynamics of rodents in southeast Asian rice fields.

BACKGROUND: The mechanisms that regulate multi-annual population dynamics of rodent pest species of cereal crops is often unknown. Better knowledge of such aspects can aid pest management and in turn improve food security and human health. The patterns and processes of the population dynamics of Rattus argentiventer, in rice fields of Indonesia, and Rattus tanezumi, in rice fields of the Philippines were assessed in this article. RESULTS: The meta-analysis of trapping data over 20 years in Indonesia, and 16 years in the Philippines indicated that rodent populations in rice fields did not show a regular multi-annual pattern. Rattus argentiventer populations in Indonesia responded to less rainfall from the current year. Rattus tanezumi populations in the Philippines responded positively to both rainfall and rainfall anomaly with a 1-year time lag. CONCLUSIONS: Our study of long-term population data indicates that certain combinations of rainfall parameters could be useful to predict years when there is higher rodent abundance in rice fields. The key rodent pest species in rice fields in Indonesia (R. argentiventer) and the Philippines (R. tanezumi) differ, and the populations of each species respond differently to rainfall anomalies. Other factors such as crop cover and water availability may also be important and should be considered in future work. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Analysis of plant and fungal transcripts from resistant and susceptible phenotypes of Leptospermum scoparium challenged by Austropuccinia psidii.

Austropuccinia psidii is the causal pathogen of myrtle rust disease of Myrtaceae. To gain understanding of the initial infection process, gene expression in germinating Austropuccinia psidii urediniospores and in Leptospermum scoparium inoculated leaves were investigated via analyses of RNAseq samples taken 24 and 48 hours post inoculation (hpi). Principal component analyses of transformed transcript count data revealed differential gene expression between the uninoculated L. scoparium control plants that correlated with the three plant leaf resistance phenotypes (immunity, hypersensitive response and susceptibility). Gene expression in the immune resistant plants did not significantly change in response to fungal inoculation, while susceptible plants showed differential expression of genes in response to fungal challenge. A putative disease resistance gene, jg24539.t1, was identified in the L. scoparium hypersensitive response phenotype family. Expression of this gene may be associated with the phenotype and could be important for further understanding the plant hypersensitive response to A. psidii challenge. Differential expression of pathogen genes was found between samples taken 24 and 48 hpi, but there were no significant differences in pathogen gene expression that were associated with the three different plant leaf resistance phenotypes. There was a significant decrease in the abundance of fungal transcripts encoding three putative effectors and a putative carbohydrate-active enzyme between 24 and 48 hpi, suggesting that the encoded proteins are important during the initial phase of infection. These transcripts, or their translated proteins, may be potential targets to impede the early phases of fungal infection by this wide-host range obligate biotrophic basidiomycete.

A comparison of visual and direct assessments of lumbar spine posture.

BACKGROUND: Posture is assessed clinically and used to guide treatment of low back pain. Collectively, the relevance of posture and clinical postural assessments have come under scrutiny. This study aimed to determine (a) the intra-rater and inter-rater reliability of visual assessments of lumbar lordosis, and (b) the agreement between visual and direct postural assessments. METHODS: Ten physiotherapists visually assessed the lumbar lordosis from 3D scans of 50 asymptomatic participants, and 15 duplicates, using a grading scale of deviations (range: 0 = normal to 3 = severe). Lumbar lordosis angle was directly assessed using the Vitus Smart 3D whole body scanner. Cohen's Kappa was used to determine the intra-rater and inter-rater reliability of visual assessments, with polyserial correlation (ps) used to determine the agreement between visual and direct assessments. RESULTS: Overall, 93% and 83% of all intra-rater and inter-rater differences in visual assessments were within a single grade point, respectively. The intra-rater and inter-rater reliability of visual assessments was moderate (κ (95%CI): 0.56 (0.45, 0.67)) and slight (κ (95%CI): 0.13 (0.08, 0.19)), respectively. The agreement between visual and direct assessments was moderate (ps = -0.41, p = 0.04). CONCLUSION: Visual assessments of lumbar posture demonstrated moderate repeatability and agreement with quantitative assessments. While agreement between assessors was slight, 83% of the visual ratings were within a single grade point, suggesting greater coherence among clinicians than our statistics suggested. As with any clinical assessments involving uncertainty, postural assessment should not solely guide treatment.

Denosumab-Induced Maxillary Osteonecrosis: A Case Study on Long-Term Complications in Multiple Myeloma Treatment.

Background: Targeted therapies like denosumab have revolutionized multiple myeloma (MM) treatment, improved patient outcomes while introducing long-term complications. This study explores a rare instance of delayed maxillary osteonecrosis post-denosumab therapy, delving into its pathophysiology and management. Methods: A 40-year-old male MM patient who developed a painful palatal lesion post denosumab treatment and diagnosed of maxillary osteonecrosis by computed tomography scan and surgical biopsy is presented. Treatment history, symptom progression, and response to the PENTOCLO protocol were analyzed. Results: Post-denosumab discontinuation osteonecrosis highlights its prolonged impact on bone metabolism. PENTOCLO treatment protocol led to significant improvement. Genetic factors influencing osteonecrosis susceptibility have been discussed and considered. Conclusions: This case underscores the need for vigilance regarding long-term complications in MM survivors, preventive strategies, including regular dental evaluations and reducing invasive dental procedures, are crucial. We advocate for an interdisciplinary approach and further research into tailored prevention and management of osteonecrosis in cancer survivors.

Functional Dynamics and Selectivity of Two Parallel Corticocortical Pathways from Motor Cortex to Layer 5 Circuits in Somatosensory Cortex.

In the rodent whisker system, active sensing and sensorimotor integration are mediated in part by the dynamic interactions between the motor cortex (M1) and somatosensory cortex (S1). However, understanding these dynamic interactions requires knowledge about the synapses and how specific neurons respond to their input. Here, we combined optogenetics, retrograde labeling, and electrophysiology to characterize the synaptic connections between M1 and layer 5 (L5) intratelencephalic (IT) and pyramidal tract (PT) neurons in S1 of mice (both sexes). We found that M1 synapses onto IT cells displayed modest short-term depression, whereas synapses onto PT neurons showed robust short-term facilitation. Despite M1 inputs to IT cells depressing, their slower kinetics resulted in summation and a response that increased during short trains. In contrast, summation was minimal in PT neurons due to the fast time course of their M1 responses. The functional consequences of this reduced summation, however, were outweighed by the strong facilitation at these M1 synapses, resulting in larger response amplitudes in PT neurons than IT cells during repetitive stimulation. To understand the impact of facilitating M1 inputs on PT output, we paired trains of inputs with single backpropagating action potentials, finding that repetitive M1 activation increased the probability of bursts in PT cells without impacting the time dependence of this coupling. Thus, there are two parallel but dynamically distinct systems of M1 synaptic excitation in L5 of S1, each defined by the short-term dynamics of its synapses, the class of postsynaptic neurons, and how the neurons respond to those inputs.

Groundwater solutes influence the adsorption of short-chain perfluoroalkyl acids (PFAA) to colloidal activated carbon and impact performance for in situ groundwater remediation.

Subsurface injection of colloidal activated carbon (CAC) is an in situ remediation strategy for perfluoroalkyl acids (PFAA), but the influence of groundwater solutes on longevity is uncertain, particularly for short-chain PFAA. We quantify the impact of inorganic anions, dissolved organic matter (DOM), and stabilizing polymer on PFAA adsorption to a commercial CAC. Surface characterization supported PFAA chain-length dependent adsorption results and mechanisms are provided. Inorganic anions decreased adsorption for short-chain PFAA (<7 perfluorinated carbons) due to competitive effects, while long-chain PFAA (≥ 7 perfluorinated carbons) were less impacted. DOM decreased adsorption of all PFAA in a chain-length dependent manner. High DOM concentrations (10 mg/L, ∼5 mg OC/L) decreased PFOA adsorption by a factor of 2, PFPeA by one order of magnitude, and completely hindered PFBA adsorption. High MW DOM has less impact on short-chain PFAA than low MW DOM, possibly due to differences in the ability to access CAC micropores. Low DOM concentrations (1 mg/L, ∼0.5 mg OC/L) did not impact adsorption. CMC (90 kDa average MW) had negligible impact on PFAA adsorption likely due to minimal CAC surface coverage. Longevity modeling demonstrated that groundwater solutes limit the capacity for PFAA in a CAC barrier, particularly for short-chain PFAA.

Reduced Insulin Resistance and Oxidative Stress in a Mouse Model of Metabolic Syndrome following Twelve Weeks of Citrus Bioflavonoid Hesperidin Supplementation: A Dose-Response Study.

Metabolic syndrome (MetS) is a cluster of metabolic abnormalities affecting ~25% of adults and is linked to chronic diseases such as cardiovascular disease, cancer, and neurodegenerative diseases. Oxidative stress and inflammation are key drivers of MetS. Hesperidin, a citrus bioflavonoid, has demonstrated antioxidant and anti-inflammatory properties; however, its effects on MetS are not fully established. We aimed to determine the optimal dose of hesperidin required to improve oxidative stress, systemic inflammation, and glycemic control in a novel mouse model of MetS. Male 5-week-old C57BL/6 mice were fed a high-fat, high-salt, high-sugar diet (HFSS; 42% kcal fat content in food and drinking water with 0.9% saline and 10% high fructose corn syrup) for 16 weeks. After 6 weeks of HFSS, mice were randomly allocated to either the placebo group or low- (70 mg/kg/day), mid- (140 mg/kg/day), or high-dose (280 mg/kg/day) hesperidin supplementation for 12 weeks. The HFSS diet induced significant metabolic disturbances. HFSS + placebo mice gained almost twice the weight of control mice (p < 0.0001). Fasting blood glucose (FBG) increased by 40% (p < 0.0001), plasma insulin by 100% (p < 0.05), and HOMA-IR by 150% (p < 0.0004), indicating insulin resistance. Hesperidin supplementation reduced plasma insulin by 40% at 140 mg/kg/day (p < 0.0001) and 50% at 280 mg/kg/day (p < 0.005). HOMA-IR decreased by 45% at both doses (p < 0.0001). Plasma hesperidin levels significantly increased in all hesperidin groups (p < 0.0001). Oxidative stress, measured by 8-OHdG, was increased by 40% in HFSS diet mice (p < 0.001) and reduced by 20% with all hesperidin doses (p < 0.005). In conclusion, hesperidin supplementation reduced insulin resistance and oxidative stress in HFSS-fed mice, demonstrating its dose-dependent therapeutic potential in MetS.

A new lysine biosynthetic enzyme from a bacterial endosymbiont shaped by genetic drift and genome reduction.

The effect of population bottlenecks and genome reduction on enzyme function is poorly understood. Candidatus Liberibacter solanacearum is a bacterium with a reduced genome that is transmitted vertically to the egg of an infected psyllid-a population bottleneck that imposes genetic drift and is predicted to affect protein structure and function. Here, we define the function of Ca. L. solanacearum dihydrodipicolinate synthase (CLsoDHDPS), which catalyzes the committed branchpoint reaction in diaminopimelate and lysine biosynthesis. We demonstrate that CLsoDHDPS is expressed in Ca. L. solanacearum and expression is increased ~2-fold in the insect host compared to in planta. CLsoDHDPS has decreased thermal stability and increased aggregation propensity, implying mutations have destabilized the enzyme but are compensated for through elevated chaperone expression and a stabilized oligomeric state. CLsoDHDPS uses a ternary-complex kinetic mechanism, which is to date unique among DHDPS enzymes, has unusually low catalytic ability, but an unusually high substrate affinity. Structural studies demonstrate that the active site is more open, and the structure of CLsoDHDPS with both pyruvate and the substrate analogue succinic-semialdehyde reveals that the product is both structurally and energetically different and therefore evolution has in this case fashioned a new enzyme. Our study suggests the effects of genome reduction and genetic drift on the function of essential enzymes and provides insights on bacteria-host co-evolutionary associations. We propose that bacteria with endosymbiotic lifestyles present a rich vein of interesting enzymes useful for understanding enzyme function and/or informing protein engineering efforts.

Pyridopyrimidinones as a new chemotype of calcium dependent protein kinase 1 (CDPK1) inhibitors for Cryptosporidium.

The protozoan protein kinase calcium-dependent protein kinase 1 (CDPK1) has emerged as a potential therapeutic target for the treatment of cryptosporidiosis. A focused screen of known kinase inhibitors identified a pyridopyrimidinone as a new chemotype of Cryptosporidium parvum (Cp) CDPK1 inhibitors. Structural comparison of CpCDPK1 to two representative human kinases, RIPK2 and Src, revealed differences in the positioning of the αC-helix that was used in the design of a potent pyridopyrimidinone-based CpCDPK1 inhibitor 7 (a.k.a. UH15-16, IC50 = 10 nM), which blocked the growth of three C. parvum strains (EC50 = 12-40 nM) as well as C. hominis (EC50 = 85 nM) in HCT-8 host cells. Pharmacokinetic and tissue distribution analyses indicated that 7 had low systemic exposure after oral administration, but high gastrointestinal concentration, as well as good Caco-2 cell permeability. Finally, 7 demonstrated partial efficacy in an IL-12 knock-out mouse model of acute cryptosporidiosis.

APOE Christchurch enhances a disease-associated microglial response to plaque but suppresses response to tau pathology.

Background: Apolipoprotein E ε4 (APOE4) is the strongest genetic risk factor for late-onset Alzheimer's disease (LOAD). A recent case report identified a rare variant in APOE, APOE3-R136S (Christchurch), proposed to confer resistance to autosomal dominant Alzheimer's Disease (AD). However, it remains unclear whether and how this variant exerts its protective effects. Methods: We introduced the R136S variant into mouse Apoe (ApoeCh) and investigated its effect on the development of AD-related pathology using the 5xFAD model of amyloidosis and the PS19 model of tauopathy. We used immunohistochemical and biochemical analysis along with single-cell spatial transcriptomics and proteomics to explore the impact of the ApoeCh variant on AD pathological development and the brain's response to plaques and tau. Results: In 5xFAD mice, ApoeCh enhances a Disease-Associated Microglia (DAM) phenotype in microglia surrounding plaques, and reduces plaque load, dystrophic neurites, and plasma neurofilament light chain. By contrast, in PS19 mice, ApoeCh suppresses the microglial and astrocytic responses to tau-laden neurons and does not reduce tau accumulation or phosphorylation, but partially rescues tau-induced synaptic and myelin loss. We compared how microglia responses differ between the two mouse models to elucidate the distinct DAM signatures induced by ApoeCh. We identified upregulation of antigen presentation-related genes in the DAM response in a PS19 compared to a 5xFAD background, suggesting a differential response to amyloid versus tau pathology that is modulated by the presence of ApoeCh. Conclusions: These findings highlight the ability of the ApoeCh variant to modulate microglial responses based on the type of pathology, enhancing DAM reactivity in amyloid models and dampening neuroinflammation to promote protection in tau models. This suggests that the Christchurch variant's protective effects likely involve multiple mechanisms, including changes in receptor binding and microglial programming.