Emerging structures and dynamic mechanisms of γ-secretase for Alzheimer's disease.

γ-Secretase, called "the proteasome of the membrane," is a membrane-embedded protease complex that cleaves 150+ peptide substrates with central roles in biology and medicine, including amyloid precursor protein and the Notch family of cell-surface receptors. Mutations in γ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer's disease. γ-Secretase has thus served as a critical drug target for treating familial Alzheimer's disease and the more common late-onset Alzheimer's disease as well. However, critical gaps remain in understanding the mechanisms of processive proteolysis of substrates, the effects of familial Alzheimer's disease mutations, and allosteric modulation of substrate cleavage by γ-secretase. In this review, we focus on recent studies of structural dynamic mechanisms of γ-secretase. Different mechanisms, including the "Fit-Stay-Trim," "Sliding-Unwinding," and "Tilting-Unwinding," have been proposed for substrate proteolysis of amyloid precursor protein by γ-secretase based on all-atom molecular dynamics simulations. While an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-bound γ-secretase, molecular dynamics simulations on a resolved model of Notch1-bound γ-secretase that was reconstructed using the amyloid precursor protein-bound γ-secretase as a template successfully captured γ-secretase activation for proper cleavages of both wildtype and mutant Notch, being consistent with biochemical experimental findings. The approach could be potentially applied to decipher the processing mechanisms of various substrates by γ-secretase. In addition, controversy over the effects of familial Alzheimer's disease mutations, particularly the issue of whether they stabilize or destabilize γ-secretase-substrate complexes, is discussed. Finally, an outlook is provided for future studies of γ-secretase, including pathways of substrate binding and product release, effects of modulators on familial Alzheimer's disease mutations of the γ-secretase-substrate complexes. Comprehensive understanding of the functional mechanisms of γ-secretase will greatly facilitate the rational design of effective drug molecules for treating familial Alzheimer's disease and perhaps Alzheimer's disease in general.

The age-dependent development of abnormal cardiac metabolism in the peroxisome proliferator-activated receptor α-knockout mouse.

BACKGROUND AND AIMS: Peroxisome proliferator-activated receptor α (PPARα) is crucial for regulating cardiac ß-oxidation in the heart, liver, and kidney. Ageing can induce cardiac metabolic alterations, but the role of PPARα has not been extensively characterised. The aim of this research was to investigate the role of PPARα in the aged heart. METHODS: Hyperpolarized [1-13C]pyruvate was used to evaluate in vivo cardiac carbohydrate metabolism in fed and fasted young (3 months) and old (20-22 months) PPARα knockout (KO) mice versus controls. Cine MRI assessed cardiac structural and functional changes. Cardiac tissue analysis included qRT-PCR and Western blotting for Pparα, medium chain acyl-CoA dehydrenase (MCAD), uncoupling protein (UCP) 3, glucose transporter (GLUT) 4 and PDH kinase (PDK) 1,2, and 4 expression. RESULTS: PPARα-KO hearts from both young and old mice showed significantly reduced Pparα mRNA and a 58-59 % decrease in MCAD protein levels compared to controls. Cardiac PDH flux was similar in young control and PPARα-KO mice but 96 % higher in old PPARα-KO mice. Differences between genotypes were consistent in fed and fasted states, with reduced PDH flux when fasted. Increased PDH flux was accompanied by a 179 % rise in myocardial GLUT4 protein. No differences in PDK 1, 2, or 4 protein levels were observed between fed groups, indicating the increased PDH flux in aged PPARα-KO mice was not due to changes in PDH phosphorylation. CONCLUSIONS: Aged PPARα-KO mice demonstrated higher cardiac PDH flux compared to controls, facilitated by increased myocardial GLUT4 protein levels, leading to enhanced glucose uptake and glycolysis.

Open Access Data Repository and Common Data Model for Pulse Oximeter Performance Data.

The OpenOximetry Repository is a structured database storing clinical and lab pulse oximetry data, serving as a centralized repository and data model for pulse oximetry initiatives. It supports measurements of arterial oxygen saturation (SaO2) by arterial blood gas co-oximetry and pulse oximetry (SpO2), alongside processed and unprocessed photoplethysmography (PPG) data and other metadata. This includes skin color measurements, finger diameter, vital signs (e.g., arterial blood pressure, end-tidal carbon dioxide), and arterial blood gas parameters (e.g., acid-base balance, hemoglobin concentration). Data contributions are encouraged. All data, from desaturation studies to clinical trials, are collected prospectively to ensure accuracy. A common data model and standardized protocols for consistent archival and interpretation ensure consistent data archival and interpretation. The dataset aims to facilitate research on pulse oximeter performance across diverse human characteristics, addressing performance issues and promoting accurate pulse oximeters. The initial release includes controlled lab desaturation studies (CLDS), with ongoing updates planned as further data from clinical trials and CLDS become available.

Automated, Transferable, and Ethanol-Free Radiosynthesis of [11C]Butanol.

Cerebral blood flow and blood-brain barrier permeability assessment are crucial hemodynamic parameters to measure under neurological conditions. In conjunction with positron emission tomography (PET), oxygen-15-labeled water has emerged as a gold standard for measuring cerebral perfusion; however, at higher flow rates, [15O]water extraction becomes nonlinear. In such a scenario, freely diffusible [11C]butanol can provide a truer estimate. Radiosyntheses of [11C]butanol reported to date are protracted, are not automated, or require ethanol in the final formulation. By using a flow-based, captive solvent approach on a commercially available radiosynthesizer, we automated and reduced the synthesis time to 28 min. Forgoing cartridge-based purification for an aqueous high-performance liquid chromatography method, we obtained high purity [11C]butanol in ethanol-free phosphate buffered saline in sufficient yields for clinical PET studies. We here report our expedited, automated, and ethanol-free radiosynthesis of [11C]butanol along with preliminary imaging of a porcine subject.

The Impact of Melanoma Imaging Biomarker Cues on Detection Sensitivity and Specificity in Melanoma versus Clinically Atypical Nevi.

Incorporation of dermoscopy and artificial intelligence (AI) is improving healthcare professionals' ability to diagnose melanoma earlier, but these algorithms often suffer from a "black box" issue, where decision-making processes are not transparent, limiting their utility for training healthcare providers. To address this, an automated approach for generating melanoma imaging biomarker cues (IBCs), which mimics the screening cues used by expert dermoscopists, was developed. This study created a one-minute learning environment where dermatologists adopted a sensory cue integration algorithm to combine a single IBC with a risk score built on many IBCs, then immediately tested their performance in differentiating melanoma from benign nevi. Ten participants evaluated 78 dermoscopic images, comprised of 39 melanomas and 39 nevi, first without IBCs and then with IBCs. Participants classified each image as melanoma or nevus in both experimental conditions, enabling direct comparative analysis through paired data. With IBCs, average sensitivity improved significantly from 73.69% to 81.57% (p = 0.0051), and the average specificity improved from 60.50% to 67.25% (p = 0.059) for the diagnosis of melanoma. The index of discriminability (d') increased significantly by 0.47 (p = 0.002). Therefore, the incorporation of IBCs can significantly improve physicians' sensitivity in melanoma diagnosis. While more research is needed to validate this approach across other healthcare providers, its use may positively impact melanoma screening practices.

Exploratory Analyses of Circulating Neoplastic-Immune Hybrid Cells as Prognostic Biomarkers in Advanced Intrahepatic Cholangiocarcinoma.

Existing clinical biomarkers do not reliably predict treatment response or disease progression in patients with advanced intrahepatic cholangiocarcinoma (ICC). Circulating neoplastic-immune hybrid cells (CHCs) have great promise as a blood-based biomarker for patients with advanced ICC. Peripheral blood specimens were longitudinally collected from patients with advanced ICC enrolled in the HELIX-1 phase II clinical trial (NCT04251715). CHCs were identified by co-expression of pan-cytokeratin (CK) and CD45, and levels were correlated to patient clinical disease course. Unsupervised machine learning was then performed to extract their morphological features to compare them across disease courses. Five patients were included in this study, with a median of nine specimens collected per patient. A median of 13.5 CHCs per 50,000 peripheral blood mononuclear cells were identified at baseline, and levels decreased to zero following the initiation of treatment in all patients. Counts remained undetectable in three patients who demonstrated end-of-trial clinical treatment response and conversely increased in two patients with evidence of therapeutic resistance. In the post-trial surveillance period, interval counts increased prior to or at the time of clinical progression in three patients and remain undetectable in one patient with continued long-term disease stability. Using our machine learning platform, treatment-resistant CHCs exhibited upregulation of CK and downregulation of CD45 relative to treatment-responsive CHCs. CHCs represent a promising blood-based biomarker to supplement traditional radiographic and biochemical measures.

Hyperferritinemia Screening to Aid Identification and Differentiation of Patients with Hyperinflammatory Disorders.

High ferritin is an important and sensitive biomarker for the various forms of hemophagocytic lymphohistiocytosis (HLH), a diverse and deadly group of cytokine storm syndromes. Early action to prevent immunopathology in HLH often includes empiric immunomodulation, which can complicate etiologic work-up and prevent collection of early/pre-treatment research samples. To address this, we instituted an alert system at UPMC Children's Hospital where serum ferritin > 1000 ng/mL triggered real-time chart review, assessment of whether the value reflected "inflammatory hyperferritnemia (IHF)", and biobanking of remnant samples from consenting IHF patients. We extracted relevant clinical data; periodically measured serum total IL-18, IL-18 binding protein (IL-18BP), and CXCL9; retrospectively classified patients by etiology into infectious, rheumatic, or immune dysregulation; and subjected a subgroup of samples to a 96-analyte biomarker screen. 180 patients were identified, 30.5% of which had IHF. Maximum ferritin levels were significantly higher in patients with IHF than with either hemoglobinopathy or transplant, and highly elevated total IL-18 levels were distinctive to patients with Stills Disease and/or Macrophage Activation Syndrome (MAS). Multi-analyte analysis showed elevation in proteins associated with cytotoxic lymphocytes in all IHF samples when compared to healthy controls and depression of proteins such as ANGPT1 and VEGFR2 in samples from hyperferritinemic sepsis patients relative to non-sepsis controls. This real-time IFH screen proved feasible and efficient, validated prior observations about the specificity of IL-18, enabled early sample collection from a complex population, suggested a unique vascular biomarker signature in hyperferritinemic sepsis, and expanded our understanding of IHF heterogeneity.

A Late Devonian coelacanth reconfigures actinistian phylogeny, disparity, and evolutionary dynamics.

The living coelacanth Latimeria (Sarcopterygii: Actinistia) is an iconic, so-called 'living fossil' within one of the most apparently morphologically conservative vertebrate groups. We describe a new, 3-D preserved coelacanth from the Late Devonian Gogo Formation in Western Australia. We assemble a comprehensive analysis of the group to assess the phylogeny, evolutionary rates, and morphological disparity of all coelacanths. We reveal a major shift in morphological disparity between Devonian and post-Devonian coelacanths. The newly described fossil fish fills a critical transitional stage in coelacanth disparity and evolution. Since the mid-Cretaceous, discrete character changes (representing major morphological innovations) have essentially ceased, while meristic and continuous characters have continued to evolve within coelacanths. Considering a range of putative environmental drivers, tectonic activity best explains variation in the rates of coelacanth evolution.

Blocking tumor-intrinsic MNK1 kinase restricts metabolic adaptation and diminishes liver metastasis.

Dysregulation of the mitogen-activated protein kinase interacting kinases 1/2 (MNK1/2)-eukaryotic initiation factor 4E (eIF4E) signaling axis promotes breast cancer progression. MNK1 is known to influence cancer stem cells (CSCs); self-renewing populations that support metastasis, recurrence, and chemotherapeutic resistance, making them a clinically relevant target. The precise function of MNK1 in regulating CSCs, however, remains unexplored. Here, we generated MNK1 knockout cancer cell lines, resulting in diminished CSC properties in vitro and slowed tumor growth in vivo. Using a multiomics approach, we functionally demonstrated that loss of MNK1 restricts tumor cell metabolic adaptation by reducing glycolysis and increasing dependence on oxidative phosphorylation. Furthermore, MNK1-null breast and pancreatic tumor cells demonstrated suppressed metastasis to the liver, but not the lung. Analysis of The Cancer Genome Atlas (TCGA) data from breast cancer patients validated the positive correlation between MNK1 and glycolytic enzyme protein expression. This study defines metabolic perturbations as a previously unknown consequence of targeting MNK1/2, which may be therapeutically exploited.

The Effect of Statins on Markers of Breast Cancer Proliferation and Apoptosis in Women with In Situ or Early-Stage Invasive Breast Cancer.

Statins, inhibitors of HMG-CoA reductase, have been shown to have potential anti-carcinogenic effects through the inhibition of the mevalonate pathway and their impact on Ras and RhoGTAases. Prior studies have demonstrated a reduction in breast tumor proliferation, as well as increased apoptosis, among women with early-stage breast cancer who received statins between the time of diagnosis and the time of surgery. The aim of this study was to evaluate the impact of short-term oral high-potency statin therapy on the expression of markers of breast tumor proliferation, apoptosis, and cell cycle arrest in a window-of-opportunity trial. This single-arm study enrolled 24 women with stage 0-II invasive breast cancer who were administered daily simvastatin (20 mg) for 2-4 weeks between diagnosis and surgical resection. Pre- and post-treatment tumor samples were analyzed for fold changes in Ki-67, cyclin D1, p27, and cleaved caspase-3 (CC3) expression. Out of 24 enrolled participants, 18 received statin treatment and 17 were evaluable for changes in marker expression. There was no significant change in Ki-67 expression (fold change = 1.4, p = 0.597). There were, however, significant increases in the expression of cyclin D1 (fold change = 2.8, p = 0.0003), p27 cytoplasmic (fold change = 3.2, p = 0.025), and CC3 (fold change = 2.1, p = 0.016). Statin treatment was well tolerated, with two reported grade-1 adverse events. These results align with previous window-of-opportunity studies suggesting a pro-apoptotic role of statins in breast cancer. The increased expression of markers of cell cycle arrest and apoptosis seen in this window-of-opportunity study supports further investigation into the anti-cancer properties of statins in larger-scale clinical trials.

Serotype-agnostic affinity purification of adeno-associated virus (AAV) via peptide-functionalized chromatographic resins.

Adeno-associated viruses (AAVs) have emerged as a prominent family of vectors for gene delivery, providing therapeutic options to diseases once deemed incurable. At the same time, they necessitate efficient and affordable purification methods that can be platformed to serve all AAV serotypes. Current chromatographic tools, while affording high product purity, fail to bind certain serotypes, provide limited yield and lifetime, and impose harsh elution conditions that can compromise the vector's activity and safety. Addressing these challenges, this work demonstrates the application of new peptide ligands as the first serotype-agnostic technology for AAV purification by affinity chromatography. Our study reveals a pH-dependent affinity interaction: AAV2, AAV3, AAV6, AAV9, and AAVrh.10 are effectively captured at neutral pH, while binding AAV1, AAV5, AAV7, and AAV8 is stronger in a slightly acidic environment. The elution of bound AAVs was achieved using magnesium chloride at neutral pH for all serotypes, consistently affording capsid yields above 50% and genome yields above 80%, together with a >100-fold reduction in host cell proteins and nucleic acids. In particular, peptide ligand A10 exhibited remarkable binding capacity (> 1014 vp per mL of resin) and purification performance for all AAV serotypes, demonstrating broad applicability for gene therapy manufacturing. Finally, this work introduces novel alkaline-stable variants of A10 and demonstrates their use as the first affinity ligands capable of performing multiple cycles of AAV2, AAV8, and AAV9 purification with intermediate caustic cleaning without loss of capacity or product quality. Collectively, these results demonstrate the promise of this technology to further the impact and affordability of gene therapy.

Glucocorticoid excess alters metabolic rate and substrate utilization via 11ß-HSD1.

Systemic glucocorticoid excess causes several adverse metabolic conditions, most notably Cushing's syndrome. These effects are amplified by the intracellular enzyme 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1). Here we determined the less well characterised effects of glucocorticoid excess, and the contribution of 11ß-HSD1 amplification, on metabolic rate in mice. Male and female C57BL/6J (wild type, WT) and 11ß-HSD1 knock out (11ß-HSD1KO) mice were treated with high-dose corticosterone or a vehicle control for 3 weeks. Indirect calorimetry was conducted during the final week of treatment, with or without fasting, to determine the impact on metabolic rate. We found that corticosterone treatment elevated metabolic rate and promoted carbohydrate utilisation primarily in female WT mice, with effects more pronounced during the light phase. Corticosterone treatment also resulted in greater fat accumulation in female WT mice. Corticosterone induced hyperphagia was identified as a likely causal factor altering the respiratory exchange ratio (RER) but not energy expenditure (EE). Male and female 11ß-HSD1KO mice were protected against these effects. We identify novel metabolic consequences of sustained glucocorticoid excess, identify a key mechanism of hyperphagia and demonstrate that 11ß-HSD1 is required to manifest the full metabolic derangement.

Children's exposure to chemical contaminants: Demographic disparities and associations with the developing basal ganglia.

Children are regularly exposed to chemical contaminants that may influence brain development. However, relatively little is known about how these contaminants impact the developing human brain. Here, we combined silicone wristband exposure assessments with neuroimaging for the first time to examine how chemical contaminant mixtures are associated with the developing basal ganglia-a brain region key for the healthy development of emotion, reward, and motor processing, and which may be particularly susceptible to contaminant harm. Further, we examined demographic disparities in exposures to clarify which children were at highest risk for any contaminant-associated neurobiological changes. Participants included 62 community children (average age 7.00 years, 53% female, 66% White) who underwent structural neuroimaging to provide data on their basal ganglia structure and wore a silicone wristband for seven days to track their chemical contaminant exposure. 45 chemical contaminants-including phthalates and their alternatives, brominated flame retardants, organophosphate esters, pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls-were detected in over 75% of wristbands. Notable demographic disparities in exposure were present, such that Non-White and lower-income children were more exposed to several contaminants. Exposure to chemical contaminant mixtures was not associated with overall basal ganglia volume; however, two organophosphate esters (2IPPDPP and 4IPPDPP) were both associated with a larger globus pallidus, a basal ganglia sub-region. Results highlight demographic disparities in exposure and suggest possible risks to a brain region key for healthy emotional development.

Implementation of a penicillin allergy protocol in open abdominal wall reconstruction: Preoperative optimization program.

INTRODUCTION: Beta-lactam prophylaxis is the first-line preoperative antibiotic in open abdominal wall reconstruction. However, of the 11% patients reporting a penicillin allergy (PA), most receive second-line, non-ß-lactam prophylaxis. Previously, abdominal wall reconstruction research from our institution demonstrated increased wound complications, readmissions, and reoperations with non-ß-lactam prophylaxis. Therefore, a collaborative quality improvement initiative was developed with the infectious disease service, and a penicillin allergy protocol was instituted that stratified patients' risk of allergic reaction with a goal to increase ß-lactam prophylaxis use. The effect of the penicillin allergy protocol on open abdominal wall reconstruction outcomes was prospectively evaluated. METHODS: Patients with penicillin allergy undergoing open abdominal wall reconstruction were identified and grouped according to penicillin allergy protocol implementation. Pre-penicillin allergy protocol underwent open abdominal wall reconstruction before January 1, 2020, predominantly receiving non-ß-lactam prophylaxis; post-penicillin allergy protocol underwent open abdominal wall reconstruction between January 1, 2020-November 1, 2023, predominantly receiving ß-lactam prophylaxis. Incidence of surgical site infection was the primary outcome. Standard and inferential statistical analyses were performed. RESULTS: Of 315 patients with penicillin allergy, 250 underwent open abdominal wall reconstruction pre-penicillin allergy protocol and 65 post-penicillin allergy protocol. Pre- and post-penicillin allergy protocol were similar in allergic reaction severity history, sex, race, age, diabetes, American Society of Anesthesiologists score, hernia defect size, and mesh type (P > .05). Post-penicillin allergy protocol had lower body mass index (33.4 ± 7.9 vs 29.8 ± 5.3 kg/m2; P = .002) and fewer active smokers (12.4% vs 1.5%; P = .019). Expectedly, post-penicillin allergy protocol received more ß-lactam prophylaxis (22.8% vs 83.1%; P < .001) and no antibiotic-induced allergic reactions. Post-penicillin allergy protocol had significantly fewer surgical site infections (24.4% vs 3.1%; P < .001), wound breakdown (16.0% vs 3.1%; P = .004), reoperations (19.2% vs 0.0%; P < .001), and readmissions (25.3% vs 9.2%; P = .006) but no statistically significant reduction in recurrence (8.4% vs 1.5%; P = .057). CONCLUSIONS: The penicillin allergy protocol safely increased the number of patients with penicillin allergy undergoing open abdominal wall reconstruction receiving ß-lactam prophylaxis and decreased the rate of surgical site infections, wound complications, reoperations, and readmissions. These data supported the systemwide implementation of the penicillin allergy protocol for both general and orthopedic surgery, which has been incorporated into the electronic medical record of 13 hospitals within the system.

Characteristics and Trends of Prehospital Encounters for Opioid Overdoses Among US Youth, 2018-2022.

This cross-sectional study analyzes characteristics of prehospital encounters for youth opioid overdoses and trends before and during the COVID-19 pandemic.

Air pollution, traffic noise, mental health, and cognitive development: A multi-exposure longitudinal study of London adolescents in the SCAMP cohort.

BACKGROUND: There is increasing evidence that air pollution and noise may have detrimental psychological impacts, but there are few studies evaluating adolescents, ground-level ozone exposure, multi-exposure models, or metrics beyond outdoor residential exposure. This study aimed to address these gaps. METHODS: Annual air pollution and traffic noise exposure at home and school were modelled for adolescents in the Greater London SCAMP cohort (N=7555). Indoor, outdoor and hybrid environments were modelled for air pollution. Cognitive and mental health measures were self-completed at two timepoints (baseline aged 11-12 and follow-up aged 13-15). Associations were modelled using multi-level multivariate linear or ordinal logistic regression. RESULTS: This is the first study to investigate ground-level ozone exposure in relation to adolescent executive functioning, finding that a 1 interquartile range increase in outdoor ozone corresponded to -0.06 (p < 0.001) z-score between baseline and follow-up, 38 % less improvement than average (median development + 0.16). Exposure to nitrogen dioxide (NO2), 24-hour traffic noise, and particulate matter < 10 µg/m3 (PM10) were also significantly associated with slower executive functioning development when adjusting for ozone. In two-pollutant models, particulate matter and ozone were associated with increased externalising problems. Daytime and evening noise were associated with higher anxiety symptoms, and 24-hour noise with worse speech-in-noise perception (auditory processing). Adjusting for air pollutants, 24-hour noise was also associated with higher anxiety symptoms and slower fluid intelligence development. CONCLUSIONS: Ozone's potentially detrimental effects on adolescent cognition have been overlooked in the literature. Our findings also suggest harmful impacts of other air pollutants and noise on mental health. Further research should attempt to replicate these findings and use mechanistic enquiry to enhance causal inference. Policy makers should carefully consider how to manage the public health impacts of ozone, as efforts to reduce other air pollutants such as NO2 can increase ozone levels, as will the progression of climate change.