ACS Chemical Neuroscience

Glycation, a non-enzymatic reaction occurring between sugars and biological macromolecules, plays a critical role in ageing and disease pathogenesis. Methylglyoxal (MG) is a highly reactive -oxoaldehyde that leads to the formation of endogenous advanced glycation end products (AGEs). These AGEs are associated with diabetes and many other diseases, including neurodegeneration and cancer. This is often through interactions with the receptor for advanced glycation end products (RAGE). Inhibition of glycation/AGEs formation using natural products to target cancer is an area of recent interest. In vitro AGEs formation was observed by browning of samples, increased fluorescence, and carbonyl stress. MG induced changes in the structure of BSA were analysed using electrophoresis, spectroscopy, TEM, AFM, DLS, and CD spectroscopy. Our results show that AGEs form random structures, oligomeric aggregates, and {beta}-sheets. Thioflavin T and Congo red staining further validated these findings. Galangin and Caffeic acid demonstrated significant antiglycation activity, suppressing AGEs formation in vitro. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/737425v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@113b391org.highwire.dtl.DTLVardef@7208a1org.highwire.dtl.DTLVardef@94c2e1org.highwire.dtl.DTLVardef@867b85_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIMethylglyoxal-induced Advanced Glycation End Products were prepared in vitro C_LIO_LIMethylglyoxal -induced structural modifications in BSA C_LIO_LIAGEs were characterised using various parameters C_LIO_LIBoth fluorescent and non-fluorescent AGEs were formed. C_LIO_LIPhytochemical treatment induced inhibition of AGEs formation C_LI

The main olfactory epithelium (MOE) is the primary site of olfaction and consists of multiple cell types including olfactory sensory neurons (OSNs), sustentacular cells, and immune cells. Neuroimmune interactions in epithelial tissues are critical in maintaining tissue function, but how OSNs and immune cells interact in the MOE in healthy and diseased states is largely unknown. Cellular responses in the MOE determine how and whether OSNs maintain olfactory function and are repaired or replenished following inflammatory environmental exposures. We hypothesized that acute nasal aeroallergen exposure alters immune cell function in the MOE to elicit a neuroprotective response, thereby preserving OSN function. We developed an environmental aeroallergen exposure consisting of one week of daily intranasal house dust mite extract (HDM) instillations. Spectral flow cytometry indicated only subtle changes in resident immune cells proportions and phenotypes in the MOE. Immunohistochemical evaluation did not reveal extensive changes in immune cell distribution in the sensory epithelium or lamina propria, but instead we observed increases in axonal olfactory marker protein (OMP) expression in the lamina propria, where resident immune cells are most abundant. To evaluate the effects of HDM exposure on OSN function, we performed live ex vivo Ca2+ imaging of MOEs from HDM- and sham-exposed transgenic mice using objective-coupled planar illumination (OCPI) microscopy. OSN responses to multiple odorants revealed increased chemosensory sensitivity and decreased across-trial adaptation in HDM-treated epithelia. These results indicate that short-term nasal aeroallergen exposure minimally alters immune cell phenotypes, and instead induces functional changes in OSN physiology that preserve olfactory function.

Per- and polyfluoroalkyl substances (PFAS) are persistent toxicants with immunological, metabolic and epithelial effects, but their relevance to inflammatory skin disease remains unclear. We developed a computational toxicology framework to test whether perfluoroalkyl sulfonate programs, especially perfluorooctanesulfonic acid (PFOS) and perfluorohexanesulfonic acid (PFHxS), converge with psoriasis-associated keratinocyte inflammation. Exposure transcriptomes were derived from GSE236956, in which human embryonic stem cell-derived epithelial-lineage models were exposed to 10 M PFAS for 8-16 days. Six PFAS were prioritized using descriptors, Tanimoto similarity, toxicology evidence, adverse outcome pathway (AOP)-like key events, exposure differentially expressed gene burden and read-across support. PFAS signatures were integrated with psoriasis bulk transcriptomes, single-cell RNA sequencing, keratinocyte-state mapping, regulator and communication inference, spatial transcriptomics and token-aware Geneformer-compatible virtual perturbation. PFOS ranked highest in integrated prioritization, followed by PFHxS and perfluorooctanoic acid. PFHxS produced a smaller but directionally informative signature within a PFOS-dominant perfluoroalkyl sulfonate footprint. The shared PFOS and PFHxS program converged with psoriasis through inflammatory keratinocyte, epidermal-stress, cytoskeletal and lipid-related modules. Single-cell and spatial analyses localized the program to activated keratinocytes and inflammatory epidermal niches, with strong spatial co-localization with inflammatory keratinocyte and epidermal stress scores. Virtual perturbation prioritized S100A9, S100A8, KRT16, IL36G, CCL20, CXCL8, FABP5, KRT17, FOS, JUN and NFKBIZ as candidate effectors. These findings support an exposure-informed, experimentally testable hypothesis linking persistent perfluoroalkyl sulfonate programs to keratinocyte inflammatory niches in psoriasis.

Background: Lead exposure is estimated to cause approximately 3.5 million premature deaths a year, yet the key ongoing sources of lead exposure are unclear. Methods: We estimated the contribution of dietary lead intake to global blood lead levels (BLLs) for 7-year-old children and 22-year-old adults by applying the All-Ages Lead Model (AALM) to calculate blood lead levels (BLLs) based on 25 total diet studies (TDS) that quantify dietary lead intake across 46 countries. Results: For children, the population-weighted average dietary lead intake in low- and middle-income countries (LMICs) (32.0 g/day) was found to be more than three times higher than in high-income countries (HICs) (9.3 g/day), and more than 10 times higher than the FDA reference level for children (2.2 g/day). The average impact on BLLs for children is estimated to be near 29 g/L in LMICs and near 12 g/L in HICs. Averaged across the TDS data, vegetables (27%) and cereals (24%) were found to contribute the most to dietary lead. Conclusions: While there are limitations associated with biokinetic modelling and the TDS data from LMICs, these results suggest that the contribution of dietary lead intake to global lead exposure is in the region of 40 to 50%, suggesting, in turn, that dietary lead intake is likely a major global driver of lead poisoning. Lead absorbed from the environment into food crops is expected to be the key driver of dietary lead. Current regulatory levels for maximum lead concentrations in foods (0.05-0.3 mg/kg) are out-of-date and may imply a dietary lead intake of 200 g/day, far higher than the FDA reference level (2.2 g/day). Collecting representative TDS data in high lead burden countries should be a priority. Further research is also recommended on upstream lead sources and pathways of lead uptake in plants, driving global food contamination.

Retinopathy of prematurity (ROP) is caused by hyperoxic exposure of prematurely born infants. The mouse model of oxygen-induced retinopathy (OIR) recapitulates pathological features of both phase I and phase II ROP. We here looked at the retinal proteins that change in response to hyperoxia in phase I of the mouse model of OIR. Using tandem mass tag labeled proteomics, we found several differentially expressed proteins (DEPs) in phase I of OIR. Of all the DEPs, we investigated the role of previously unknown protein NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 4-like 2 (NDUFA4L2). NDUFA4L2 protein and its paralog NDUFA4 are both mitochondrial complex I proteins; however, here we demonstrate that NDUFA4L2 changes in both phases of OIR, with no changes in its paralog NDUFA4, implying its unique function in pathophysiology of the disease. We demonstrate that NDUFA4L2 is an oxygen-sensitive protein and regulates retinal endothelial cell migration by rescuing isocitrate dehydrogenase flux impaired by hyperoxia in phase I of OIR.

Aldehyde dehydrogenases (ALDH) are enzymes that catalyze the NAD(P)+-dependent oxidation of aldehydes into carboxylic acids, playing roles in detoxification, biosynthesis, and regulatory functions. Dysfunction of ALDH is associated with serious conditions such as alcohol intolerance, cancer, cardiovascular problems, and neurological disorders. In humans, ALDH1A1 and ALDH1A3 isoforms act as retinaldehyde dehydrogenases and are overexpressed in various cancers, where high levels are associated with increased tumor malignancy, cancer stem cell traits, and therapeutic resistance. ALDH1A3 is recognized as a promising target for anticancer therapies, with several inhibitors, mainly reversible, developed to specifically target it or the enzyme family. Since ALDH enzymes can also display esterase activity, we used this property to develop an in vitro assay specifically targeting the esterase function of ALDH1A3. A highly conserved active-site cysteine in ALDH1A3 is located at the bottom of two converging channels, which define the substrate- and cofactor-binding pockets. To target this catalytic cysteine, we screened a library of 3,200 cysteine-focused covalent fragments. This led to the identification of Z3405279217 (Z34), an acrylamide-based covalent compound that inhibits both ALDH1A1 and ALDH1A3 at sub-micromolar levels. Biochemical and biophysical tests confirmed that Z34 acts as a time-dependent, covalent, and irreversible binder to the active-site cysteine. In this work, we determined the Cryo-EM structure of the ALDH1A3-Z34 complex at 2.26 [A] resolution, confirming the covalent attachment to the catalytic cysteine of Z34. Notably, two mutually exclusive covalent binding modes were observed: one occupying the substrate-binding pocket and the other the cofactor-binding region. Z34 displayed unexpected binding modes within the active site and holds promise as a lead compound for future drug development. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=184 HEIGHT=200 SRC="FIGDIR/small/738401v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@982d1forg.highwire.dtl.DTLVardef@ba86f2org.highwire.dtl.DTLVardef@1f19f2borg.highwire.dtl.DTLVardef@8e807_HPS_FORMAT_FIGEXP M_FIG C_FIG

"Mirror life", self-replicating organisms composed of non-natural-chirality biomacromolecules, presents a future threat with potentially global consequences. Consequently, there is strong agreement among experts that it should not be created. However, there is some disagreement over how effective existing medical countermeasures might prove against mirror bacteria in the event that they were created. Here, we leverage computational chemistry methods including docking and molecular dynamics to determine the likely binding efficacy of existing antibiotics against natural and mirror bacterial protein targets. We find that most existing antibiotics fail to bind to mirror bacterial protein targets, unlike their natural-chirality targets. This suggests altered binding of current medical countermeasures, which may impact the antimicrobial activity against mirror bacteria were the latter were created.

Psilocybin shows therapeutic promise for several psychiatric disorders, but the acute perceptual and cognitive alterations produced by conventional doses (10-25 mg) require in-clinic supervision, which limits scalability. Whether the therapeutically relevant pharmacology of psilocybin can be separated from its hallucinogenic activity remains unresolved. To address this gap, we conducted a Phase 1, randomized, double-blind, placebo-controlled, single ascending dose study to characterize the safety, pharmacokinetics and pharmacodynamics of low doses of psilocybin. Fifty-six healthy adults received a single oral dose of psilocybin (0.5, 1.0, 1.5, 2.5, 3.5 or 4.0 mg) or matching placebo across seven sequential cohorts, with each dose escalation reviewed by a Drug Safety Review Committee. All participants completed the study with no serious adverse events or discontinuations. Treatment-emergent adverse events were comparable to placebo and most prominently arose as somnolence. Plasma psilocin appeared rapidly with a median time to maximum concentration < 1 h with dose-proportional exposure and a short terminal half-life. Subjective drug effects were dose-related and became distinguishable from placebo at doses at or below 2.5 mg. Peak subjective ratings increased with dose, while any signs of hallucinations or altered-states scores remained low and not different than placebo. Psychophysiological engagement was confirmed by a clear dose-dependent pupillary dilation while cognitive performance (attention, vigilance, working memory, impulse control) showed no dose-dependent decrement and state anxiety did not increase at any dose. These findings indicate that the perceptible pharmacology of psilocybin can be dissociated from significant perceptual alterations and cognitive impairment at low doses. They further support controlled investigations in outpatient Phase 2 studies evaluating the safety and feasibility of repeated, self-administered low-dose psilocybin. ClinicalTrials.gov #NCT07710027

Traumatic brain injury (TBI) is one of the leading causes of emergency room visits in children under 10. Children are potentially more vulnerable to the adverse effects of TBI, given that their brains are still developing at the time of injury. Indeed, early life TBI has been linked to cognitive, social, and mood-related impairments later in life. The neuroimmune system has been implicated in adult TBI mechanisms and plays numerous key roles in brain development, making it an interesting candidate for linking pediatric TBI and prolonged behavioral alterations. Here we establish a rat model of mild pediatric TBI to investigate the relationship between early life TBI, acute responses of neuroimmune cells, and chronic behavioral dysregulation. At postnatal day 15, which is roughly equivalent to toddler age, male and female rat pups received a TBI via lateral fluid percussion injury. At 3 days post injury, TBI increased microglia and astrocyte coverage locally in the Perilesional Cortex but not in more distant corticolimbic regions. However, the hippocampus and prefrontal cortex did exhibit increased expression of the phagocytic marker CD68 in microglia, suggesting widespread glial activation even in the absence of gross coverage change. TBI also impacted mast cells, early-response innate immune cells, increasing their number and degranulation in multiple regions. In the juvenile and early adult periods, TBI impaired cognitive function, reduced sociability, and increased avoidance, with no change in anxiety-like behavior. Later in adulthood, TBI continued to impact cognitive behavior, increasing risky decision-making and impairing optimization months after injury. Together, these results suggest that pediatric TBI causes lasting cognitive and social dysregulation, possibly via acute neuroimmune alterations following injury at a critical period of brain development.

Alzheimers disease (AD) causes progressive memory loss and disorientation. It is preceded by a prolonged preclinical phase marked by pathological changes in medial temporal lobe regions involved in spatial navigation. Spatial navigation tasks have been proposed for early AD detection, and altered navigation performance was reported in older carriers of the apolipoprotein E (APOE) {varepsilon}4 allele, the major genetic risk factor for sporadic AD. However, whether spatial navigation or other cognitive abilities are affected in younger {varepsilon}4 carriers remains unclear. Here, we genotyped 1000 healthy young adults (18-35 years) who completed the app-based navigation game "Sea Hero Quest" and several tasks assessing working memory, processing speed, executive functioning, and face recognition. {varepsilon}4 carriers ({varepsilon}3{varepsilon}4, N = 88) showed no significant differences from non-carriers ({varepsilon}3{varepsilon}3, N = 327) in spatial navigation or other cognitive abilities, supported by equivalence testing and Bayesian analyses. Exploratory findings suggested altered spatial navigation in {varepsilon}2 carriers ({varepsilon}2{varepsilon}2/{varepsilon}2{varepsilon}3/{varepsilon}2{varepsilon}4, Ns = 7/51/7) versus {varepsilon}3{varepsilon}3 controls, who stayed closer to environmental borders and showed better memory updating, face recognition, and processing speed. Therefore, APOE-related behavioural differences in young adults appear small at best, highlighting the need for paradigms sensitive to very subtle changes decades before potential dementia onset.

Copper (Cu) is an essential metal involved in neurobiological processes including energy metabolism and neurotransmission, yet dysregulated Cu levels may adversely affect brain health and olfactory performance. Although olfactory dysfunction has primarily been studied in older adults and neurodegenerative disease, adolescence is a critical period of brain maturation during which the olfactory system may be particularly vulnerable. This cross-sectional study examined associations between Cu exposure, olfactory bulb (OB) volume, and olfactory performance in 200 adolescents and young adults (64% female; ages 13 - 25) from the Public Health Impact of Metals Exposure cohort. Cu concentrations in blood, urine, hair, and saliva were measured using inductively coupled plasma mass spectrometry. T2-weighted magnetic resonance imaging scans estimated left, right, and total OB volumes using a three-stage deep learning pipeline. Olfactory performance was assessed using the Sniffin Sticks test. Weighted quantile sum regression evaluated associations between a Cu mixture index and OB outcomes, while standard linear regression models assessed individual Cu biomarkers. Models were adjusted for age and sex. A higher Cu index was associated with reduced left (Beta= -0.72, 95% CI [-1.42, -0.02]), right (Beta = -0.79, 95% CI [-1.43, -0.15]), and total OB volume (Beta= -1.55, 95% CI [-2.85, -0.25]), as well as lower odor threshold scores (Beta = -0.23, 95% CI [-0.42, -0.03]). Individual biomarkers were not independently associated with outcomes. These findings suggest that Cu exposure may adversely affect olfactory neurodevelopment during adolescence and highlight the importance of studying environmental exposures relevant to long-term neurological health.

Extensive experiments document that SPARCL1, a secreted protein that is produced primarily by astrocytes in brain and endothelia throughout the body and that is also known as Hevin, enhances synapse formation. However, the mode of action of SPARCL1 at synapses remains unclear owing to divergent results in the literature. Here, we use cultured neurons from newborn male and female mouse embryos to show that the C-terminal follistatin-like and Ca2+-binding domains of SPARCL1, which account for only 35% of the total SPARCL1 sequence, are sufficient to potently enhance synapse numbers. SPARCL1 acts at nanomolar concentrations at which SPARCL1 does not robustly bind to neurexins, neuroligins or neurexin/neuroligin complexes but avidly interacts with all teneurins. Strikingly, the follistatin-like domain of SPARCL1 on its own strongly binds to teneurins but is unable to stimulate synapse formation. Only when combined with the SPARCL1 Ca2+- binding domain does the follistatin-like domain induce synapses, suggesting that SPARCL1 enhances synapse numbers by binding to teneurins via its C-terminal follistatin-like domain and by activating synapse formation via its Ca2+-binding domain. SIGNIFICANCE STATEMENTSPARCL1 (also known as Hevin) is a synaptogenic factor that is produced primarily by astrocytes in brain, and that enhances synapse formation. How SPARCL1 acts at synapses, however, remains unclear because divergent results describe its binding partners at synapses and the sequences involved in its synaptogenic activity remain unclear. In the present study, we show that SPARCL1 avidly binds to the presynaptic teneurins adhesion molecules, that this binding is mediated by its small follistatin-like domain, and that its synaptogenic activity requires both its follistatin-like and its Ca2+-binding EC domains. Thus, our results suggest that SPARCL1 is recruited to developing synapses by binding of its follistatin-like domain to teneurins and then induces synapse assembly via its Ca2+-binding domain.

Neuroendocrine cells communicate with other cells by releasing neurotransmitters or hormones by exocytosis, which involves SNARE-mediated fusion between secretory vesicles and the plasma membranes of the secreting cells. In neurons two plasma membrane SNARE proteins, Syntaxin-1a and SNAP25, join with the vesicle membrane SNARE protein Synaptobrevin-2 to form a four-helix bundle, which drives membrane fusion. The assembly of these SNAREs, which is highly orchestrated in cells, has been intensely studied in solution using fragments of the SNARE proteins without their transmembrane domains or lipid anchors. However, in cell and model membranes, Syntaxin and SNAP25 are known to oligomerize and cluster, and little is known about how clustering affects their incorporation into SNARE complexes. In cells, the SM protein Munc18 has been implicated in aiding secretory vesicle docking and facilitating SNARE complex assembly through its interactions with Syntaxin. To understand how Munc18 orchestrates SNARE complex assembly on membranes, we employed protein reconstitution in model membranes as well as biochemical and biophysical assays to show that lipid-dependent oligomerization of Syntaxin affects Munc18-Syntaxin binding and SNAP25 insertion into the plasma membrane acceptor SNARE complex. We showcase the consequences of the different modes of Munc18-Syntaxin and SNAP25 interaction on Syntaxins oligomerization and orientation relative to the membrane surface, as well as on docking and fusion of purified insulin granules. We also determined low-resolution structures by cryoEM in nanodiscs and on the surface of proteoliposomes of membrane-bound assembly states of Munc18/Syntaxin and Munc18/Syntaxin/SNAP25 complexes.

Cognitive flexibility is an executive function that allows individuals to adjust behaviour in response to changing environmental demands. We assessed volitional switching under uncertainty, without rule-based learning, in the Change Your Mind task. Nineteen patients with obsessive-compulsive disorder (OCD), 19 patients with attention-deficit hyperactivity disorder (ADHD) and matched control participants (20 per group) completed the task whilst undergoing a functional MRI scan. The task was a two-alternative forced choice paradigm where each stimulus was presented twice successively, with spurious feedback following the first presentation. This allowed participants the opportunity to repeat or change their response. Participants with ADHD changed their response more frequently than controls following a previously correct response, associated with reduced accuracy on the second trial. This was accompanied with smaller differences between change and repeat trials in the superior frontal gyrus, paracingulate gyrus and frontal pole compared to controls. Participants with OCD did not differ from healthy controls in their performance but exhibited greater activity on both change and repeat trials in the pre- and postcentral gyri than controls. These results point to distinct neurobehavioural differences in patients with ADHD and OCD underlying what is often termed more broadly inflexible behaviour.

Cortisol, our stress hormone, exerts widespread influence on neural activity. However, its influence on the aperiodic component of the electroencephalography power spectrum remains to be investigated. Given individual differences in the capacity to cope with stress and adversity, it also remains unclear whether trait resilience moderates this relationship. Hence, the present study examined whether individual differences in trait resilience moderates the association between resting cortisol and aperiodic activity. Participants (N=145) completed various self-report questionnaires (e.g., trait resilience). Electroencephalography was recorded over a 20-minute baseline period, followed by salivary cortisol collection. The results revealed a significant moderating effect of trait resilience in the occipital scalp region. Specifically, higher cortisol concentration was associated with flatter 1/f slopes amongst individuals with low trait resilience, whereas this association was reversed amongst those with high trait resilience. Overall, our findings highlight the role of individual differences in trait resilience in shaping hypothalamic-pituitary-adrenal axis-related neural dynamics.

Hippocampal place cell activity represents an animals location in space; yet, how hippocampal neuronal population dynamics change with spatial learning and the mechanisms underlying these activity changes, which drive allocentric navigation to a learned goal, are poorly understood. To address these questions, we performed calcium imaging with a novel wire-free waterproof miniaturized microscope to image the activity of large populations of hippocampal CA1 neurons during spatial learning of a two-dimensional navigational task, the Morris water maze. We followed the same cells during learning and were able to directly examine how each neuron in the ensemble, and the ensemble as a whole, changes its response properties. We found that neuronal spatial selectivity increased and population decoding of spatial location improved as mice learned to navigate to the goal. Viral CRISPR knock out of Grin1 (encoding the essential GluN1 NMDA receptor subunit) in dorsal hippocampal neurons, dramatically reduced long-term potentiation in CA1. This manipulation also prevented the increase in spatial selectivity and improvement of population decoding with spatial learning and resulted in learning deficits in the Morris water maze. Together, our results show that dorsal hippocampus NMDAR-dependent synaptic plasticity is essential for the learning-dependent refinement of CA1 place selectivity and improvement in population decoding of space.

Reactive nitrogen species (RNS), particularly peroxynitrite generated from the reaction of superoxide and nitric oxide, are implicated in thermally-induced oxidative stress but remain difficult to resolve in live coral cells. We optimized fluorescent dye strategies to directly quantify superoxide, nitric oxide, and peroxynitrite production in thermally stressed Pocillopora acuta cell suspensions. Thermal stress was associated with an increase in intracellular peroxynitrite concentration, but not in its precursors, nitric oxide and superoxide, highlighting challenges with the application of fluorescent probes and their controls to live coral cells. Compounds developed for mammalian systems often translate poorly to non-model systems such as corals: strong endogenous fluorescence and multiple membrane barriers within the coral symbiocyte, for instance, limited the function of the nitric oxide probe, DAF-2DA. Despite these limitations, the detection of peroxynitrite in live, thermally stressed P. acuta cells represents a step forward in understanding the mechanism of coral bleaching. We also outline strategies for improving the performance of commercial dyes in non-model systems, including media optimization with EDTA treatment to preserve both cell viability and probe performance.

Polysubstance use is rising and linked to heightened overdose rates and increased treatment challenges, further exacerbated by increasing detection of adulterants (e.g., xylazine) in the street drug supply. Harm reduction groups provide sterile syringes in exchange for used ones, creating a unique opportunity to characterize prevalent polysubstance combinations and inform translational and preclinical research We analyzed residues from used syringes (N=3,168) obtained from several harm reduction organizations in Jefferson County, KY (Jan-Dec 2025) for the presence of substances using gas chromatography mass spectrometry (GC-MS). We classified compounds as adulterants (e.g., diphenhydramine [DPH]/Benadryl), byproducts/precursors of synthesis (e.g., 4-ANPP), and recreational drugs (e.g., meth). We excluded byproducts/precursors and determined the most frequent substance and pairs/trios containing one or more recreational substance. Results. Of 3,168 syringes, 2,522 (79.61%) tested positive for substances. Out of those positive, the top recreational substances were meth (n=1,387; 54.99%), fentanyl (n=1,220; 48.37%), and heroin (n=653; 25.89%). Top adulterants were DPH (n=1021; 40.48%), dimethyl sulfone (n=749; 29.69%), and lidocaine (n=736; 29.18%). The most common pairs were DPH+fentanyl (n=670; 26.57%), lidocaine+fentanyl (n=659; 26.13%), dimethyl sulfone+meth (n=621; 24.62%), and fentanyl+heroin (n=484; 19.19%). The most common trios were DPH+lidocaine+fentanyl (n=369; 14.63%), DPH+fentanyl+heroin (n=327; 12.97%), lidocaine+fentanyl+heroin (n=297; 11.77%), diphenhydramine+xylazine+fentanyl (n=273; 10.82%), and meth+lidocaine+fentanyl (n=262; 10.39%). Our findings highlight evolving patterns of multiple-opioid and opioid-stimulant polysubstance use, generating insights that can be rapidly applied to strengthen clinical, preclinical, and translational polysubstance research. These insights allow for investigations into biobehavioral mechanisms and consequences of emerging use patterns, accelerating development of novel therapeutics.

Background: Plasma phosphorylated tau-217 (pTau-217) measurements for use in Alzheimer disease (AD) identification require thresholds to define positivity and there exist different approaches to operationally defining the boundary. We compared amyloid {beta} (AB) PET-anchored and distribution-based positivity cut-off values and explored how these mapped onto latent biomarker states. Methods: We analysed plasma pTau-217 measured in the Bio-Hermes-001 cohort (N = 990) using an immunoassay (Lilly) and mass spectrometry assay (University of Gothenburg). Gaussian mixture models were used to identify latent classes and thresholds were derived in two ways: achieving 90% specificity for AB PET positivity and exceeding the mean + 2SDs of the lowest latent class. We explore classes in reference to AB PET status and clinical diagnosis, as well as agreement between approaches using Cohen kappa for both assays. Results: In both assays, three latent biomarker classes were identified with monotonic increases in AD clinical diagnosis and AB PET positivity. PET-anchored thresholds showed lower specificity but higher sensitivity to amyloid positivity than distribution-based thresholds. Overall agreement between the approaches was acceptable (k = 0.678 for Lilly and 0.575 for University of Gothenburg), with disagreement concentrated in the intermediate latent class. Classes with the lowest and highest pTau-217 concentrations were classified consistently using both thresholds Discussion: The two thresholding approaches yielded similar classifications at both the negative and positive tail of the observed biomarker distribution, but classify intermediate concentrations differently. The boundary definition influenced pTau-217 positivity more than the analytical platform itself. Thresholding approaches may capture different pTau-217 biomarker states, therefore such methodological decisions should be grounded in the context of the intended application.

IntroductionBipolar disorder (BD) is characterized by recurring episodes of mania and depression. Despite extensive research, the pathophysiology underlying these mood swings remains elusive. Emerging evidence indicates a potential role for neuroinflammation and microglial activation in the pathophysiology of BD. MethodsWe employed a reverse-translational approach to generate directly induced microglia-like (iMG) cells from peripheral blood monocytes of a single patient with BD, repeatedly sampled across depressive, manic, and subsequent depressive phases. RNA sequencing was performed on iMG cells at each time point to identify differentially expressed genes related to mood state transitions. ResultsA thorough analysis of longitudinal gene expression data has led to the identification of three functional gene categories: "state-dependent genes", "depression-to-mania transition genes (named: firing genes)", and "mania-to-depression transition genes (named: extinguishing genes)". A total of 168 firing, 59 extinguishing, and 77 state-dependent genes were identified. Notably, functional annotation revealed that, compared to the extinction gene set, the firing gene set was enriched in immune and inflammatory response pathways, particularly early-response cytokines such as IL1B and TNF. ConclusionsBased on these findings, we propose that inflammatory immunomodulation by microglia contributes to mood switching in BD, especially in the process of depression-to-mania transition. The classification of genes by their relationship to state transitions offers a novel framework for understanding the molecular mechanisms underlying this complex disorder and may identify potential therapeutic targets to stabilize mood. Further validation with larger cohorts is warranted.