Journal of Cerebral Blood Flow & Metabolism

Background: Cardiovascular, kidney, and metabolic diseases are closely interconnected and may share common pathophysiological mechanisms, including microvascular dysfunction. Although cardiac 82Rb-PET/CT is routinely used for myocardial perfusion imaging, its potential for integrated cardio-renal perfusion assessment and cardiometabolic phenotyping remains underexplored. We recently developed a compartment modelling approach to quantify renal perfusion from routine cardiac 82Rb-PET/CT, enabling simultaneous assessment of cardio-renal perfusion. However, real-world imaging registries integrating these phenotypes with longitudinal clinical outcomes are lacking. Aim: To establish a real-world imaging registry that repurposes routine cardiac 82Rb-PET/CT by integrating PET-derived hemodynamic measures and CT-derived imaging biomarkers with detailed clinical, echocardiographic, laboratory, and clinical outcome data. Methods: The APOLLO registry is a single-centre retrospective registry of consecutive patients undergoing routine cardiac 82Rb-PET/CT at Alrijne Hospital (Leiderdorp, the Netherlands) between 2021-2023. Clinical, laboratory, medication, echocardiographic, and imaging data were collected to enable integrated cardio-renal perfusion assessment and cardiometabolic phenotyping. Inverse probability of selection weighting analysis was performed to account for renal coverage selection criteria. Cardiac perfusion was quantified using myocardial blood flow and myocardial flow reserve, while renal perfusion was derived using our previously developed compartment-model. Additional phenotyping included adiposity and frailty-related biomarkers, great vessel diameters, vascular calcification, diastolic dysfunction grading, H2FPEF score, Cardio-Kidney-Metabolic (CKM) staging, and longitudinal assessment of major adverse cardiovascular events. Conclusion: APOLLO registry extends routine cardiac 82Rb-PET/CT beyond myocardial perfusion imaging by integrating cardio-renal perfusion measurements with detailed cardiometabolic, clinical, and outcome phenotypes. This real-world registry provides a unique platform for future mechanistic and outcome-based research across the CKM disease spectrum.

Background: Low-density lipoprotein cholesterol (LDL-C) is an established risk factor for atherosclerotic cerebrovascular disease, but its effects on the cerebral microcirculation are poorly defined. We investigated whether LDL-C is associated with pericyte dysfunction in acute ischemic stroke (AIS) and explored underlying mechanisms. Methods: Serum soluble platelet-derived growth factor receptor-{beta} (sPDGFR{beta}) was measured in two independent AIS cohorts (n=97 and n=86). Cerebral pericyte transcriptional responses to LDL-C were analyzed by single-cell RNA sequencing in Apoe-knockout mice fed control or high-fat diet (n=4 [male/female: 2/2]/group), and cultured human brain pericytes were exposed to purified human LDL cholesterol with or without N-acetyl-L-cysteine. Results: Higher serum sPDGFR{beta} was associated with greater neurological deficit and circulating neurofilament light chain. LDL-C positively correlated with sPDGFR{beta} in both clinical cohorts. High-fat diet induced coordinated suppression of type-I interferon pathways, and a positive shift in reactive oxygen species-related transcriptional programs in mouse pericytes; exploratory sex-by-diet analyses suggested larger transcriptional responses in females. In cultured human pericytes, LDL-C induced oxidative-stress, lipid-handling, and ferroptosis-associated transcriptional programs while suppressing type-I interferon signaling. Cross-species enrichment analysis showed that LDL-C-induced and -repressed signatures in cultured pericytes aligned with the sex-by-diet interaction in Apoe-knockout mice. LDL-C also reduced cell-surface PDGFR{beta} and increased sPDGFR{beta} release in cultured pericytes, which were significantly attenuated by N-acetyl-L-cysteine, whereas LDH activity increased numerically but not significantly. Conclusions: Clinical and experimental findings support an LDL-pericyte axis linking atherogenic lipid stress to cerebral microvascular dysfunction, with possible sex-dependent modulation of oxidative stress and type-I interferon signaling as potential mechanisms.

Background: Whether ethnoracial differences in cerebral small vessel disease (cSVD) appear in multimarker burden, particular MRI manifestations, or both, and how they relate to Life's Essential 8 (LE8) cardiovascular health and cognition, remain unclear. Methods: This cross-sectional study included 44,982 participants and an age- and sex-matched subsample of 1,426 with reviewed lacune and cerebral microbleed (CMB) ratings. White, South Asian, Black, Chinese and Mixed participants were compared on 0-2 (white matter hyperintensity [WMH]/enlarged perivascular space [ePVS]) and 0-4 (adding CMB and lacunes) composite scores and each marker. LE8 was related to WMH and composite burden, and cognitive means were compared by group. Models were age-, sex- and center-adjusted with false-discovery-rate correction. Results: Both composite scores differed across groups (0-2: P=0.00010; 0-4: P=0.0011), with greater burden in Black than South Asian (0-4: OR 1.66; 95% CI, 1.21-2.28) and Chinese participants (OR 2.36; 1.51-3.70), whereas Black-White contrasts were not detected. Black participants had higher WMH volume than White participants (=0.209; 0.110-0.308), robust to deprivation adjustment and segmentation method; South Asian participants had fewer ePVS (0.82; 0.72-0.93). No ethnoracial-group differences in lacune or CMB counts were detected after correction. Higher LE8 was associated with lower WMH volume (0.13 per SD; 0.17 to 0.09) and lower two-marker burden (OR 0.89 per SD; 0.87-0.91) without detected ethnoracial moderation. Black participants, who had the least favorable LE8 scores, and South Asian participants had lower global cognition than White participants (z 0.76 and 0.57 versus 0.24) despite differing WMH profiles; the pooled WMH-cognition association was null. Conclusions: Ethnoracial differences in multimarker cSVD burden were evident but marker-dependent: WMH showed the clearest Black-White difference; focal-lesion contrasts were inconclusive. Better cardiovascular health related to lower WMH and aggregate cSVD burden across groups, whereas cognitive differences did not track cSVD burden, supporting prospective prevention and cognition studies.

BACKGROUND: White matter hyperintensities (WMHs), the principal imaging manifestation of cerebral small vessel disease, lack an animal model that produces pathology of sufficient magnitude to validate potential therapeutics. We characterized white matter (WM) degeneration in a renovascular hypertension (RVH) rat model, interrogated its mechanism, and tested its relevance in patients. METHODS: RVH was induced by two-kidney, two-clip surgery and assessed by T2-weighted and diffusion MRI, myelin and axonal histology, and blood-brain barrier (BBB) leakage markers. The influence of angiotensin II (Ang II) on barrier function in brain endothelial cells was examined using transendothelial electrical resistance and reactive oxygen species (ROS) assays. Losartan was infused intracerebroventricularly to block brain AT1R (Ang II type 1 receptor) without systemic blood pressure reduction. WMH burden was compared between patients with and without renal artery stenosis, and WMH progression across antihypertensive classes was assessed in the CHALLENGE (Korea), MSS2 (UK), LBC1936 (UK), and SPRINT-MIND-MRI (US) cohorts. RESULTS: Approximately two-thirds of RVH rats developed WMHs that expanded between 7 and 9 weeks, accompanied by reduced fractional anisotropy, demyelination, axonal and mature oligodendrocyte loss, and glial activation. IgG, albumin, and fibrinogen leakage was confined to affected WM. Ang II impaired endothelial barrier function and generated ROS through AT1R. Intracerebroventricular losartan attenuated WM pathology and improved behavior while blood pressure remained comparably elevated. Patients with renal artery stenosis had higher WMH volumes (10.52 versus 6.52 mL; P = 0.035). Angiotensin receptor blocker use was associated with the slowest tertile of annual WMH progression in the Korean cohort (OR, 2.57 [95% CI, 1.20-5.61]) and among White participants in SPRINT-MIND-MRI (OR, 3.52 [95% CI, 1.05-12.29]). CONCLUSIONS: RVH produces prominent ischemic WM degeneration driven by AT1R signaling, identifying a blood pressure-independent therapeutic target with corroborating clinical evidence.

Rationale: Thrombi are fragile, heterogeneous, and difficult to study with available methods, yet understanding their molecular composition and local microenvironment in stroke is critical to elucidating stroke pathophysiology and improving patient outcomes. Objective: We used a novel platform for harvesting and analyzing intracranial thrombi from endovascular thrombectomy for large vessel occlusion to define the cellular and transcriptomic landscape of thrombi. Methods and results: We performed single-nuclei RNA sequencing (snRNA-seq) on three human intracranial thrombi to define their molecular composition and microenvironment. Across 5,143 nuclei, we identified 8 distinct cellular populations, including monocytes and T cells. Monocytes displayed transcriptional changes on gene and regulon levels suggestive of transdifferentiation. We integrated our snRNA-seq data with publicly available single cell RNA-sequencing (scRNA-seq) data from asymptomatic and symptomatic atherosclerotic carotid plaques, and scRNA-seq data from healthy brain vasculature. We identified shared transcriptional programs between carotid and thrombi monocytes along dimensions including inflammation and endothelial activation, supporting the notion that thrombi monocytes undergo transdifferentiation in stroke. We also inferred potential ligand-receptor interactions that may occur at the site and time of occlusion. Conclusion: Our novel application of snRNA-seq to thrombectomy specimens has allowed us to uncover the full diversity of cell types present in thrombi, including low-abundance and novel cell populations, and to provide evidence of cellular plasticity and intercellular communication at the site of occlusion. This detailed definition of the cellular populations involved in stroke will facilitate mapping of novel interventional targets with direct functional relevance and facilitate greater personalization of post-reperfusion therapy.

Background: Understanding fetal brain responses to hypoxia-ischemia is of growing interest, as it remains unclear to what extent these responses differ from those of newborns and whether developmental adaptations during gestation contribute to such differences. Materials and methods: Using a combination of broadband near-infrared spectroscopy (bNIRS) and diffuse correlation spectroscopy (DCS), we measured brain microvascular oxygen saturation (StO2), total hemoglobin concentration (THC), relative cerebral blood flow (rCBF), and the oxidation state of cytochrome c oxidase (oxCCO) during an acute ischemic challenge in the brains of five rabbit fetuses in utero. Simultaneous measurements were acquired from four control fetuses located in the contralateral uterine horn. Results: During the hypoxia-ischemia phase, we observed a rapid reduction of CBF (47% +/- 29%) and StO2, (from 64.7% +/- 1.5% at baseline to 40.6% +/- 2.0%) together with an increase of oxCCO (3.7 uM +/- 0.5 uM). Conclusion: The simultaneous increase in oxCCO and decrease in rCBF and StO2 during hypoxia-ischemia reveals a cerebral response pattern that differs from that commonly reported in the newborn brain. These findings support the hypothesis that unique developmental adaptations influence fetal cerebral metabolism during hypoxic-ischemic stress.

White matter hyperintensities on brain magnetic resonance imaging are established markers of cerebral small vessel disease and typically associate inversely with brain volume in the general population, reflecting irreversible tissue loss. In Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy, a monogenic small vessel disease caused by NOTCH3 cysteine-altering mutations, white matter hyperintensities may instead reflect tissue water accumulation and perivascular space dilation rather than net structural damage. Whether this distinct pathophysiological relationship is detectable at population level among carriers of NOTCH3 cysteine-altering variants without clinically manifest disease remains unknown. We conducted a cross-sectional neuroimaging study using UK Biobank data acquired between 2014 and 2023. Among 44,943 participants with complete brain magnetic resonance imaging data (mean age 64 years +/- 8 years), 96 carried heterozygous NOTCH3 cysteine-altering variants within epidermal growth factor-like repeat domains 7 to 34 and 44,847 were non-carriers. White matter hyperintensity volume was automatically quantified and normalized to total intracranial volume. Brain parenchymal fraction was defined as combined gray and white matter volumes divided by total intracranial volume. Lacunes were manually assessed in all carriers. Linear regression and generalized additive models examined the association between white matter hyperintensity volume and brain parenchymal fraction stratified by genotype, adjusting for age, sex, lacune count, and vascular risk factors. NOTCH3 variant carriers showed markedly higher normalized white matter hyperintensity volume than non-carriers (0.83% versus 0.36%; P<10^-8) but only marginally higher brain parenchymal fraction (81.1% versus 80.5%; P=0.03). In non-carriers, white matter hyperintensity volume was inversely associated with brain parenchymal fraction (beta=-0.116% per 1% increase; P=3.10^-6). In contrast, NOTCH3 variant carriers demonstrated a positive association (beta=+0.51%; P=0.019), strengthened after adjusting for lacune count (beta=+0.61%; P=0.006). A significant genotype-specific interaction confirmed this divergence (P=0.036), persisting across age groups and after vascular risk factor adjustment. NOTCH3 cysteine-altering variant carriers identified at population level exhibit a fundamentally distinct white matter hyperintensity-brain volume relationship compared with non-carriers, consistent with lesions reflecting tissue water accumulation rather than irreversible structural loss at this early, predominantly preclinical disease stage. These findings establish that genetic context modifies neuroimaging biomarker interpretation in cerebral small vessel disease and underscore the need for genotype-aware approaches when evaluating white matter hyperintensities as markers of disease severity or progression.

Purpose: To evaluate, within a synthetic pulmonary-artery benchmark, whether biomarker-aware super-resolution improves hemodynamic endpoint fidelity in 4D flow MRI. Methods: A 3D residual channel attention network (RCAN) was trained on 22 CFD simulations from 11 pulmonary-artery geometries with 2x spatial degradation. The original primary comparison evaluated full biomarker-aware training against a combined divergence-temporal-regularization control across 14 matched seeds on a fixed six-case test set. Additional matched analyses subsequently separated divergence and adjacent-frame temporal-difference regularization and evaluated biomarker supervision in a controlled 2x2 design with a common reconstruction schedule. Results: In the original primary comparison, biomarker-aware training reduced PI error relative to the matched combined-regularization control (12.76 +/- 2.34% vs. 17.12 +/- 1.23%; paired difference -4.35 percentage points [95% CI -5.58, -3.09]; p = 0.0015). In the matched factorial analysis, biomarker supervision reduced PI error without (-2.235 percentage points [95% CI -3.514, -0.849]) and with (-4.125 percentage points [95% CI -5.392, -2.732]) combined regularization. PI improvement was not mirrored by uniformly improved reconstruction metrics: PSNR changed by -0.058 (p = 0.50) and +0.144 dB (p = 0.28), while SSIM decreased by 0.009 (p = 0.004) and 0.007 (p = 0.009), respectively. Divergence alone changed PI by +0.034 percentage points [95% CI -0.705, 0.809] while reducing DivRMS by 1.869 percentage points; temporal-difference regularization increased PI error by 1.562 percentage points [95% CI 0.594, 2.439]. Conclusion: Within this synthetic, fixed-case RCAN benchmark, biomarker supervision improved PI under both regularization conditions. PI improvement was not mirrored by uniformly improved reconstruction metrics. Temporal-difference - not divergence - regularization was the only isolated component associated with reproducible PI deterioration. These findings are configuration-specific and require geometry-independent and in vivo validation.

Objective: To develop and validate a dual-probe Diffuse Correlation Spectroscopy (DCS) system for non-invasive and simultaneous, monitoring of cerebral blood flow (CBF) in the bilateral Middle Cerebral Artery (MCA) territories, and expanding the utility of conventional DCS limited to cortical-volume-based CBF measurements to vessel-specific cerebral perfusion monitoring. Methods: A dual-probe DCS system was designed for non-invasive monitoring of MCA-specific perfusion. Probe placement and protocol optimization study has been performed using anatomical landmarks, motor and speech activation tasks in healthy volunteers. System stability and repeatability were further evaluated in a pilot cohort of 30 healthy (age, 25{+/-}7 years) participants using optimized probe position and protocol. A bilateral MCA ischemic Lacunar Infract stroke case report also validated the feasibility of the system in clinical settings. Results: Measurements demonstrated superior sensitivity towards MCA-territory perfusion at targeted probe locations compared to off-MCA positions. In pilot cohort, significant increase of 30.34 {+/-} 21.56% and 36.48 {+/-} 21.22% in rCBF corresponding to hand squeeze and speech task respectively showed reproducible physiological responsiveness of the system (p<0.001). Measurement done on a patient with bilateral MCA ischemic Lacunar Infract stroke showed a significant change of 30% during speech for both the MCAs but no significant change is observed for hand squeeze tasks. Conclusion: The custom built dual-probe DCS system enables non-invasive, operator-independent, targeted and continuous monitoring of rCBF within bilateral MCA territories. Significance: This approach enables the potential use of DCS system for bilateral and vessel-specific monitoring of cerebral perfusion in the MCA territories.

Introduction: Cerebral ischemia induces a reduction in brain pH. GPR4, a proton-sensing G protein-coupled receptor is highly expressed in vascular endothelial cells. Pharmacological inhibition of GPR4 with NE52-QQ57 (NEQQ) reduces ischemia-induced blood-brain barrier (BBB) disruption and brain injury. To facilitate targeting GPR4 in vivo, it is important to better define the effect of NEQQ on post-ischemia signaling and the pharmacokinetics of NEQQ in vivo. Methods: We performed biochemical analysis following transient middle cerebral artery occlusion (tMCAO). We used Liquid Chromatography-Mass spectrometry (LC-MS/MS) to quantify the concentration of NEQQ in serum, brain, and peripheral tissues. Results: NEQQ administration decreased the phosphorylation of PKA substrates, PKC substrates, ERK1/2, and CREB. LC-MS/MS analysis detected NEQQ in both ipsilateral and contralateral hemisphere of the brain at 5 h and 24 h after reperfusion, demonstrating that NEQQ crosses the BBB. In peripheral tissues, NEQQ exhibited highest level in kidney and lowest in the heart. In sham controls, average serum concentrations were ~4 and 0.9 g/g at 5 and 24 h, respectively. Following tMCAO, ipsilateral brain exhibited higher levels as compared to the contralateral side at 5 h while the difference diminished at 24 h. Conclusions: NEQQ attenuated the ischemia-induced activation of multiple signaling pathways. NEQQ exhibited broad distribution in peripheral organs, and its brain level was sufficient for GPR4 inhibition at 24 h after injection. These findings support the use of NEQQ as a pharmacological inhibitor of GPR4-mediated signaling following ischemic stroke.

In pre-clinal studies, VC108, a novel GPR39 inhibitor, increased myocardial O2 tension (mpO2) during different phases of acute myocardial infarction (AMI). The purpose of this work was to investigate the temporal effects of VC108 on mpO2 using a novel population PK/PD model developed from preclinical data using healthy animals and animals subjected to AMI protocols. PK/PD simulations were then performed to explore mpO2 dynamic in untested experimental scenarios. VC108 PK data fitted well to a two-compartment model with linear elimination with body weight, sex, and nominal dose identified as significant covariates influencing clearance and/or central compartment volume. Applying indirect effect model principles for representing mpO2 flux, a structural population PK/PD model was developed to capture mpO2 dynamics during different AMI phases: before and during coronary occlusion and after reperfusion. The model successfully captured basal mpO2 homeostasis, ischemic decline, and reperfusion overshoot, while quantifying the contribution of VC108 to collateral blood flow and functional recovery. Dose response relationships were simulated to measure the effect of different VC108 dose levels on permanent damage, i.e. a reduction in mpO2 at steady state after AMI. The probability of remaining below predefined damage thresholds (mpO2 reduction of 5% to 20%) increased with dose in both sexes, with females consistently achieving greater protection that plateaued around 1 mg/kg of VC108 for higher permanent damage. This model represents a valuable tool to describe, for the first time, VC108 efficacy data and pharmacokinetics with ischemia/reperfusion dynamics and quantify its effect in untested dose levels.

The hippocampus is particularly vulnerable to hypoxia, yet freedivers, who repeatedly undergo voluntary breath-hold hypoxia, do not appear to show the memory impairments commonly reported after involuntary hypoxic exposure. We investigated whether freediving training is associated with functional connectivity reorganization at the whole-brain and hippocampal levels, and whether hippocampal connectivity relates to preserved episodic memory performance. Seventeen male recreational freedivers underwent fMRI before and after a 7-month standardized training period, and 20 matched aerobic-trained controls were assessed at baseline. Functional connectivity analyses examined (i) whole-brain ROI-to-ROI connectivity, (ii) seed-to-voxel connectivity from the bilateral hippocampus and selected cortical seeds, and (iii) associations between hippocampal connectivity and episodic memory. Compared with controls, freedivers showed distinct connectivity patterns during apnea and rest. After training, whole-brain analyses revealed reorganization involving salience, frontoparietal, sensorimotor, visual, and cerebellar systems. Hippocampal analyses showed reduced connectivity with sensorimotor and default mode regions, alongside increased connectivity with cerebellar and visual areas, with stronger effects after training. In freedivers, specific post-training hippocampal connectivity was associated with episodic memory performance. These findings suggest that repeated voluntary hypoxia during freediving training is associated with selective functional reorganization of hippocampal and large-scale brain networks. This pattern may reflect adaptive neuroplasticity linked to preserved episodic memory under intermittent hypoxic exposure.

Purpose: To quantify, in a computational fluid dynamics (CFD) benchmark, how spatial degradation, temporal acquisition and noise change the error of plane-based pulmonary-artery flow endpoints. Methods: Twenty-two historical, non-converged CFD simulations (11 geometry families) were voxelised at 2 mm with 80 frames per cycle. Simulations with numerical divergence were excluded, leaving 13 (7 families). Fields were degraded to 4 and 8 mm and with noise, plane waveforms were sampled at 20 phases with one-interval averaging, and errors were computed against the noise-free reference waveform on 66 geometric planes. Family-mean paired differences are reported with t-based 95% confidence intervals under an analysis plan fixed in advance. Results: Spatial degradation from 2 to 4 mm increased full-waveform nRMSE by 0.0032 [0.0021, 0.0043], in 7 of 7 families; cycle-mean flow bias accounted for 23% of the squared error, against 60% at 8 mm. With SNR scaled to voxel volume, the increase was not resolved (0.0002 [-0.0012, 0.0015]). Twenty-phase acquisition increased PI error (0.0223 [0.0214, 0.0233]) and diastolic-trough timing error (0.63 [0.52, 0.74] frames) more than spatial degradation, and its point estimates for these endpoints were larger with every recovery method; the nRMSE ordering and peak timing depended on the recovery method. The implementation of the downsampling operator mattered: an alternative, corner-aligned implementation of the same 4 mm degradation gave a larger spatial effect (nRMSE difference 0.0010 [0.0002, 0.0017]). Conclusion: In this benchmark, a 2 to 4 mm degradation produced a small, consistent, mostly shape-related nRMSE increase that depended on the noise model, whereas 20-phase acquisition changed PI error and trough timing more. The results describe benchmark behaviour, not clinical acquisition requirements.

Ogerin, a positive regulator of GPR68, reduces infarct volume and attenuates blood-brain barrier (BBB) leakage post transient middle cerebral artery occlusion (tMCAO). These data support the potential use of Ogerin for ischemic protection. For therapeutic interventions, tissue distribution, kinetics, and brain penetration are important characteristics for a compound. For these reasons, we performed liquid chromatography-mass spectrometry (LC-MS) analysis of Ogerin in mice. At 3 hours following intraperitoneal (IP) injection, liver exhibited highest level of Ogerin among all major organs assessed. We further analyzed time-dependent changes in Ogerin concentration in serum following intravenous delivery. Brain Ogerin level was ~140 ng/g at 2 hour and ~0.06ng/g at 24 hours. The brain-to-serum ratio of Ogerin was ~0.6 at 5 hr. To determine the effect of Ogerin on signaling, we collected samples 24 hours after tMCAO with or without Ogerin delivered and performed Western blotting. Consistent with the diminished level of Ogerin in brain at 24 hour, tMCAO increased similar changes in phosphorylation of PKA substrates and PKC substrates in vehicle- and Ogerin-treated groups. The pharmacokinetic data suggests that Ogerin is effective mainly during acute hours after injection. This finding generates important insights on the design of effective protocol for Ogerin delivery to potentiate GPR68 function in vivo.

Background and Purpose: Neonatal hypoxia-ischemia (NHI) is a leading cause of mortality and long-term neurodevelopmental disability. Therapeutic hypothermia (TH) is currently the only established treatment for NHI; however, its efficacy remains limited, underscoring the need for adjunctive neuroprotective strategies. Lactate is now regarded as a major metabolic substrate of the brain and has previously been shown to exert neuroprotective effects following experimental NHI. We investigated whether lactate enhances hypothermia-induced neuroprotection and evaluated the optimal timing of administration and potential underlying mechanisms. Methods: Postnatal day 7 Wistar rats were subjected to NHI using the Rice-Vannucci model and treated with TH alone (2h at 32{degrees}C), sodium L-lactate alone, or combined L-lactate-TH. Animals underwent longitudinal magnetic resonance imaging (MRI) and behavioral assessments, complemented by histological, immunohistochemical, and Western blot analyses, including assessment of protein lactylation. The effect of sodium L-lactate administration timing relative to TH was also evaluated. Results: Lactate significantly enhanced the neuroprotective effects of TH, particularly when administered before hypothermia, resulting in greater lesion recovery, reduced neuroinflammation and apoptotic cell death, preserved neuronal integrity, and improved long-term motor and cognitive outcomes. Combined treatment preserved neuronal lactate transporter, prevented NHI-induced astrocytic glutamate transporter upregulation, modulated lactylation markers, supporting coordinated metabolic and epigenetic adaptations following NHI. Conclusions: Early lactate administration enhances the neuroprotective efficacy of TH following NHI. These findings identify lactate as a promising adjunct to TH and support its translational potential as a metabolic strategy to improve outcomes following NHI brain injury.

Background Heart rate fragmentation (HRF) has emerged as a novel marker of sinoatrial instability and neuroautonomic dysregulation and is a predictor of incident cardiovascular disease (CVD) events and cardiovascular mortality. Leveraging heart rate fragmentation as a novel measure may help us better understand the prognostic significance of physical activity. Physical activity (PA) patterns are multidimensional and difficult to study holistically, however. We sought to examine for novel PA clusters in a cohort of veteran men and evaluate their prognostic significance based on their associations with neuroautonomic dysregulation. Methods In this cross-sectional study, we examined 602 male veterans from the Vietnam Era Twins Study of Electrophysiology in Posttraumatic Stress Disorder (VETS-EP) who were enrolled between 2022 and 2026. Accelerometry data were used to derive physical activity parameters across 6 domains: volume, sedentary behavior, intensity, diurnal pattern, fragmentation, and variability. Heart rate fragmentation was assessed using percentage of inflection points (PIP), inverse average length of segments (IALS), percentage of short segments (PSS), and percentage of alternating segments (PAS). Gaussian mixture models were used to derive digital phenotypes of physical activity, and associations with heart rate fragmentation were assessed using linear mixed models. Results Participants had a mean age of 73.8 {+/-} 2.9 years and 93.2% reported White race. Two overlapping phenotypes of physical activity patterns were identified: a compact-early phenotype, characterized by earlier activity timing and slightly greater overall activity, and a diffuse-late phenotype, characterized by later activity timing and greater heterogeneity in activity volume. In fully adjusted models, the diffuse-late phenotype was associated with higher PIP, the primary outcome ({beta}: 1.199, 95% CI: 0.034 to 2.363, p-value: 0.044), and higher IALS ({beta}: 0.01210, 95% CI: 0.00048 to 0.02373, p-value: 0.041), but not PSS or PAS, compared with the compact-early phenotype. Conclusions In older male veterans, Gaussian mixture model phenotyping identified two overlapping physical activity phenotypes, differing mainly in diurnal timing and in the dispersion of overall activity, that were associated with modest differences in heart rate fragmentation. These phenotypes provide a framework for capturing complex physical activity patterns. Future prospective studies representing diverse populations are needed to validate such phenotypes.

Targeted alpha therapy with 225Ac is a promising modality for cancer treatment, as shown in recent preclinical and clinical studies. Preclinical imaging of 225Ac is essential to fully understand the biokinetics of developmental 225Ac radiopharmaceuticals. Although single photon emission computed tomography (SPECT) is typically used to achieve this in vivo, conventional preclinical scanners struggle to provide high contrast and accurate quantification for 225Ac imaging due to the very low injected activities (below 1 kBq/g), the unfavorable gamma-ray branching ratios (<26%), and its complex decay chain with several gamma-ray emissions. In this work, we employ a compact CZT-based Compton camera to achieve quantitative tomography of 225Ac daughters in live mice at 18.5 kBq (0.5 Ci) injected activities. Three mice bearing 22Rv1 prostate cancer subcutaneous xenografts were scanned in a single bed position for 30 minutes following intravenous administration of 18.5 kBq of the Anti-CD46 225Ac-Macropa-PEG4-YS5 conjugate. We successfully visualized the in vivo biodistributions of the 225Ac daughters 221Fr and 213Bi, distinguishing between the tumor xenograft and the central organs. Quantification of the tumor uptake from the images revealed an activity as low as 1.1 kBq. In vivo activity quantification computed from the images was compared to ex vivo biodistribution measurements using a gamma counter after harvesting the tissue, showing strong agreement.

Purpose We examined whether drinking a small volume of cold water during orthostatic stress attenuates the fall in systolic blood pressure (SBP). Methods In a randomized crossover study, 19 healthy young adults underwent 15 min of 60 degree head-up tilt under three conditions on separate days: no water, 200 mL of body-temperature water (37 degrees Celsius), and 200 mL of cold water (4 degrees Celsius). Drinking began 5 min after tilting and lasted 1 min. Hemodynamics and tympanic temperature were analyzed using covariate-adjusted linear mixed models with within- and between-condition comparisons. Results During drinking, SBP increased from pre-drinking values by 9.54 mmHg (95% confidence interval [CI] 5.58 to 13.50) with body-temperature water and 14.70 mmHg (10.74 to 18.66) with cold water. After cold water ingestion, SBP remained higher by 5.95 mmHg (95% CI 1.99 to 9.91) over the first 4 min and 4.84 mmHg (0.88 to 8.80) over the subsequent 5 min. No clear post-drinking increases occurred with body-temperature water. SBP was higher with cold water than with both other conditions during the first 4 min after drinking, and higher than with body-temperature water during the subsequent 5 min. After cold water ingestion, stroke volume was higher and heart rate lower than before drinking, and tympanic temperature declined between the two post-drinking periods. Conclusion Drinking 200 mL of cold water after blood pressure had fallen attenuated the reduction in SBP during continued orthostatic stress in healthy young adults.

Myocardin (MYOCD) is the principal trigger-switch for vascular smooth muscle cell (VSMC) growth arrest and the cyto-contractile program of differentiation. While much is known about MYOCD-dependent VSMC differentiation, limited information exists as to its transcriptional regulation. Here, we report moderate mRNA expression of Myeloid Ecotropic viral Integration Site 1 (MEIS1) in both human and mouse VSMCs. MEIS1 mRNA is reduced in parallel with myocardin mRNA and protein under conditions of VSMC de-differentiation. Loss- and gain-of-Meis1 expression studies in cultured human VSMCs and the mouse carotid artery support MEIS1 as an activator of myocardin and VSMC differentiation. CRISPR-mediated knockout of the endogenous Meis1 gene in vitro and elicited lower levels of VSMC contractile markers and an increase in growth rate. Similarly, Femoral artery wire injury, in mice lacking Meis1 showed and increased of neointima formation. Mechanistically, we identified a conserved MEIS1 response element in the proximal promoter of myocardin, that appears to contribute to the promoter activity, suggesting a potential regulatory interaction. These results suggest a previously unrecognized role for the homeodomain protein MEIS1 in the activation of myocardin and the quiescent, VSMC differentiated state.

Vasculogenic mimicry (VM) describes the ability for tumor cells to mimic endothelial cells and form tumor-lined blood vessels. Although VM is associated with poor prognosis, resistance to therapeutics and metastasis, its presence, relevance and functionality have been debated, largely due to the techniques employed to determine its presence. Dual CD31 and periodic acid-Schiff (PAS) histological staining, the method widely used to detect VM within tumor tissue, is hampered by issues with artifacts of 2D sections and does not assess active blood flow through vessels and hence cannot confirm vessel functionality. Here, we present a 3D imaging pipeline to detect functionally perfused VM and host vessels within mouse tumor models. Mice tumor models are intravenously injected with fluorescently-labelled tomato lectin which binds to the lumen of functional blood vessels. These tumors are thickly sliced, optically-cleared, stained with endothelial markers and imaged using light-sheet microscopy. We apply this imaging modality to image tumors from six breast cancer patient-derived tissue xenograft models, an orthotopic mammary cancer model and two small cell lung cancer circulating-tumor cell explant models, where VM vessels, mosaic vessels and host-VM vessel junctions can be detected. To our knowledge, this is the largest collection of 3D VM vessel images to date, providing convincing evidence of the presence and functionality of VM within tumors and defining the level of evidence necessary to detect VM in vivo.