Abstract Background and aims Ischemic injury appears as a hypodensity on non-contrast CT (NCCT). The relative NCCT map (rNCCT) enables automated infarct core segmentation based on relative voxel-wise attenuation differences (Figure1). We evaluated the association between rNCCT-segmented core metrics with poor functional outcome. Methods We retrospectively analyzed baseline NCCT of consecutive stroke patients with an anterior circulation large vessel occlusion, presentation > 3 hours from last-seen-well, and pre-stroke modified Rankin Scale (mRS) < 3. Infarct core was automatically segmented using rNCCT thresholded at ≥4.9% relative hypodensity. Core volume and mean relative hypodensity were assessed for association with poor functional outcome (90-day mRS ≥3). Results We included 185 patients with median rNCCT core volume of 23 mL (IQR 9–62) and median relative hypodensity within this core of 7.04% (IQR 6.34–8.30; Table1). In univariate analysis, both rNCCT core volume (OR 1.02, 95% CI 1.01–1.03) and hypodensity (OR 1.46, 95% CI 1.17–1.82) were associated with poor outcome (P < 0.001). The hypodensity in the core was more pronounced in patients with poor vs good outcome (7.4 vs 6.6%; P < 0.001). In multivariable analysis hypodensity was excluded due to multicollinearity, but rNCCT core volume independently predicted poor outcome (OR 1.01, 95% CI 1.00–1.03, P = 0.02; Table2). Conclusions rNCCT-based core volume independently predicted poor functional outcome. The hypodensity within the core was more severe in patients with poor outcome, suggesting prognostic value of hypodensity beyond core volume. These findings support the use of the rNCCT as a standalone tool for core segmentation and outcome prediction in patients admitted > 3 hours. Conflict of interest Sources of Funding LV gratefully acknowledges financial support for this publication by the Fulbright U.S. Student Program, which is sponsored by the U.S. Department of State and Fulbright Belgium/Luxembourg/Schuman. Its contents are solely the responsibility of the author and do not necessarily represent the official views of the Fulbright Program, the Government of the United States, or Fulbright Belgium/Luxembourg/Schuman. Furthermore, LV discloses receipt of financial support for the research and authorship of this article by Research Foundation Flanders, PhD fellowship fundamental research 1113925 N; and by the Belgian American Educational Foundation. ATS received grants from the Fulbright Program, the Monahan Foundation, the Philippe Foundation, the France-Stanford Center for Interdisciplinary Studies and the Rotary International. PK receives funds from 2025-26 NIH StrokeNet Training Program (U10NS086487) and has received funds from NIH/NINDS (grant nr R01NS075209). RL is senior clinical investigator (1841923 N) at the Research Foundation Flanders (Fonds Wetenschappelijk Onderzoek, FWO). The CRISP-2 study (PI MGL) was funded by the NIH and by the Research Foundation Flanders (Fonds Wetenschappelijk Onderzoek, FWO), project number G049620N. Disclosures LV reports no disclosures relevant to the manuscript. PK is a cofounder and shareholder of inSteps BV.. JD, SC, ATS, PS, NY, MM, and SK report no disclosures relevant to the manuscript. J.J. Heit reports consulting fees from Medtronic and MicroVention, and is a member of the medical and scientific advisory board for iSchemaView. AW reports consulting fees from Bayer. GWA reports stock holdings in iSchemaView; and compensation from Biogen, iSchemaView and Genentech for consultant services. RL reports institutional fees paid to KU Leuven for consultancy by iSchemaview. Figure 1 - belongs to Background and aims Table 1 - belongs to Results Table 2 - belongs to Conclusions

Background and Purpose: Persistent hypoperfusion despite successful endovascular treatment (EVT) for acute ischemic stroke (AIS) due to large-vessel occlusion (LVO), which results from either residual distal macrovascular occlusion or microvascular dysfunction ("no-reflow"), is increasingly recognized as a potential contributor to poor outcome. We aimed to characterize early post-EVT perfusion abnormalities on MRI and assessed their relationship with a panel of inflammatory biomarkers. Methods: We prospectively included patients with LVO-related AIS and successful (modified Thrombolysis in Cerebral Infarction [mTICI] ≥2b) recanalization who underwent MRI perfusion (MRP) as early as feasible after EVT and blood sampling before, during, immediately after and 24 hours after EVT. mTICI was assessed by an independent reader. Hypoperfusion within the affected vascular territory was assessed using three complementary approaches: (1) significant macrovascular hypoperfusion (Tmax>6s) in any location; (2) wedge-shaped perfusion deficits on Tmax maps, indicative of distal emboli; and (3) visual microvascular hypoperfusion within the infarct core on cerebral blood volume (CBV) and/or flow (CBF) maps (two-rater assessment). Associations between macrovascular hypoperfusion and 37 inflammatory biomarkers, measured using multiplex immunoassays, were analyzed using Mann–Whitney U tests with false discovery rate (FDR) correction. Results: Seventy-one patients were included. Median time from recanalization to MRP was 45 (19-118) min. Tmax>6s hypoperfusions were found in 21% of all patients; percentages decreased with better mTICI grades: 45%, 13% and 0% in mTICI 2b, 2c, and 3, respectively. Wedge-shaped hypoperfusion deficits were observed in 97% of mTICI2b, 44% of mTICI2c, and 8% mTICI3 cases (see Figure 1 for examples). Microvascular hypoperfusion was rare (6%, see Figure 2 for examples). Several inflammatory markers showed uncorrected associations with Tmax>6s hypoperfusion, but none survived FDR correction (Figure 3). Conclusions: Early perfusion deficits after EVT most often reflect residual distal emboli. Hypoperfusion on Tmax>6s maps was not associated with inflammatory biomarkers. Nevertheless, our integrated imaging and biomarker strategy—including samples collected immediately distal to the clot during EVT—lays the foundation for future mechanistic and therapeutic studies targeting microvascular reperfusion failure.

BACKGROUND:Deep learning enables the extraction of ischemic lesion size and hypodensity imaging markers from noncontrast CT (DLNCCT) in patients with acute ischemic stroke, but it remains unclear whether those markers can predict post-transfer core volume. METHODS:We performed a post-hoc analysis of prospectively enrolled patients transferred from a primary to a comprehensive center (PSC/CSC) for endovascular treatment (EVT). Using a validated deep-learning NCCT segmentation method, we quantified total lesion volume (per 10mL), modified net water uptake (mNWU %), and severely hypodense volume (≤26 HU per 10mL) and compared these markers with core-lab-rated ASPECTS (per point decrease) and CTP-based evaluation for their association with (adjusted regression coefficient [95%CI]) and predictive performance in addition to baseline variables (R2±SE) for post-transfer CSC-admission DWI core volume. RESULTS:We included 420 patients (239[57%] males) with a median age of 72 years (IQR:61;80). We observed 11.2mL (95%CI:8.3;14.1] larger post-transfer core volumes per point decrease in ASPECTS, 10.0mL (95%CI:6.8;13.3) and 20.0mL (95%CI:12.7;27.2) larger post-transfer core volumes per 10 mL increase in total and severely hypodense DLNCCT volume, respectively. mNWU was not associated with post-transfer core volume (p=0.63). In addition to clinical baseline and CTA variables, post-transfer core volume prediction with ASPECTS (R2:0.49±0.02) and DLNCCT (R2:0.50±0.02) did not differ significantly (p=0.58). Compared with using CTP imaging markers (R2:0.56±0.02), adding ASPECTS (R2:0.63±0.02, p<0.01) and DLNCCT (R2:0.65±0.01, p<0.01) improved performance for post-transfer core volume prediction. CONCLUSION:Total and severely hypodense DLNCCT volumes are independent predictors for post-transfer core volume. These DLNCCT markers improved CTP-based post-transfer core volume prediction.

The primary cilium is a solitary, microtubule-based organelle present on most vertebrate cells, where it functions as a central hub for sensing and transducing extracellular signals. This Cell Science at a Glance article highlights how primary cilia integrate key signalling pathways - including Hedgehog, G protein-coupled receptor, TRP ion channel, receptor tyrosine kinase and transforming growth factor β superfamily signalling - to regulate cellular processes, tissue architecture and organ function. We also describe how defects in ciliary structure or signalling give rise to ciliopathies, a diverse group of disorders affecting multiple organs and systems. Finally, we explore emerging insights into how dynamic changes in ciliary composition generate cell type- and context-specific signalling signatures, positioning the cilium as a convergence point for multiple signalling branches that coordinate development and homeostasis in time and space. The accompanying poster provides further detail on signalling modules and specializations across cell types.

BACKGROUND AND OBJECTIVES:It is unknown whether acute CT perfusion (CTP) core imaging may underestimate the follow-up infarct. We hypothesize that infarct underestimation occurs especially in late-presenting patients and that underestimated infarct can partially be detected on baseline noncontrast CT (NCCT). METHODS:We included patients with acute anterior circulation ischemic stroke who underwent baseline NCCT and CTP imaging, complete endovascular reperfusion, and follow-up MRI from the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke (DEFUSE 3) trial and a consecutive, monocenter cohort. We divided patients into early (<6 hours) and late (6-24 hours) presenters. We performed semiautomated segmentations of the acute ischemic lesion on NCCT using 5% relative density difference (rNCCT>5%) and used the relative cerebral blood flow <30% to segment the CTP core. On coregistered images, we performed volumetric and voxel-based analyses to compare infarct estimations by imaging modality. Spatial accuracy for the follow-up infarct was assessed using the Dice similarity coefficient (DSC) and balanced accuracy. RESULTS:We included 109 patients with a median age of 70 (interquartile range [IQR] 31-93) years of whom 52% were female. The follow-up infarct was underestimated by the CTP core (mean absolute volume difference [MAVD] = 14 mL [SD 36], p < 0.001), but not by the union lesion (MAVD = 3 mL [SD 32], p = 0.76). Infarct underestimation was greater in late presenters (median 17 mL [IQR 7-33] vs 7 mL [IQR 4-25] in early presenters, p < 0.01) and in patients with poor collaterals (median 20 mL [IQR 8-56] vs 8 mL [IQR 4-20] in patients with good collaterals, p < 0.01). Median 25% of the infarct missed by the CTP core could be detected on baseline rNCCT in late presenters (vs. median 3% in early presenters). The combined rNCCT>5% and CTP core lesion more accurately detected the follow-up infarct compared with the CTP core alone (median DSC 0.37 [IQR 0.06-0.55] vs 0.18 [IQR 0-0.42] and median balanced accuracy 0.67 [IQR 0.53-0.75] vs 0.56 [IQR 0.50-0.67], p < 0.001 for both). DISCUSSION:Underestimation of follow-up infarct by CTP is substantial and the follow-up infarct can partially be detected by baseline NCCT, especially in patients with stroke with delayed presentation. Combining rNCCT>5% and CTP increases the accuracy for predicting the follow-up infarct.

Introduction: Ischemic core growth rate in patients with a large vessel occlusion varies during transfer from a primary stroke center (PSC) to a comprehensive stroke center (CSC) for thrombectomy. Patients at risk for a high growth rate may be optimal candidates for neuroprotective treatments. We determined if deep learning based CT lesion (DLCT) volume and density measures are associated with growth rate. Methods: Patients with CT and CTP at the PSC and CTP or DWI at the CSC were included from the prospective CRISP 2 study. Growth rate per hour (mL/h) was measured as the difference between the CTP core volume (relative cerebral blood flow <30%) at the PSC and CTP ischemic core or manually segmented DWI lesion volume at the CSC. We used a validated deep learning model to segment the ischemic lesion on non-contrast CT and determined lesion volume, density in the lesion, and relative hypodensity; the percentage difference with contralateral voxels. Additional clinical, CT angiography, and CTP measurements were considered as independent variables (Figure 1). Stepwise regression with combined forward/backward selection optimized for the Akaike Information Criterion was used to select variables. For each variable, we report adjusted regression slopes with 95% confidence interval (aB[95%CI]) for their association with growth rate. R2 and adjusted R2 are reported to reflect model performance. Results: We included 269 patients; 113(42%) women, median age was 71(IQR:60-80) years, 185(69%) had witnessed onset of stroke symptoms. The stepwise optimized regression model had an R2 of 0.44 (adjusted R2: 0.41). DLCT variables with significant associations with growth rate were volume (aB/10mL:3.2[95%CI:2.3; 4.1]), >20% relative hypodensity volume (aB/10mL:-8.5[-11.6; -5.3]), and density standard deviation in the lesion (aB/HU:2[0.8; 3.2]). Penumbra volume (aB/10mL:-0.5[-0.8; -0.2]) was associated with core growth rate, while ischemic core volume (aB/10mL:0.62[-0.03; 1.27]) was not. Tan collaterals score (aB per point:-4.7[-6.6; -2.9]), clot burden score (aB/point:-1.6[-2.1; -1.0]), female sex (aB:-3.2[-5.7; -0.7]), and admission systolic blood pressure (aB/10mmHg:0.7[0.3; 1.2]) were also significantly associated with core growth rate. Conclusion: DLCT based volume and density measures have a strong association with ischemic core growth rate during interhospital transfer which might indicate that DLCT also identifies tissue at risk for irreversible ischemic damage.

BACKGROUND:For patients with acute ischemic stroke due to a large vessel occlusion admitted in primary stroke centers, helicopter transfer to comprehensive stroke centers is often used to expedite access to mechanical thrombectomy. Some studies have suggested that vibrations generated during helicopter transport might enhance intravenous thrombolysis (IVT) efficacy. We aimed to evaluate the impact of helicopter transfer, compared with ground transportation, on interhospital recanalization and functional outcomes. METHODS:We conducted a retrospective analysis of 2 prospectively collected cohorts of anterior circulation acute ischemic stroke due to a large vessel occlusion patients transferred to 2 comprehensive stroke centers (Stanford, CA, November 2019 to January 2023, and Montpellier, France, January 2015 to January 2017) for mechanical thrombectomy consideration with arterial imaging both at the primary stroke center and on comprehensive stroke center arrival. The primary outcome was interhospital recanalization, determined by comparison of the baseline and posttransfer arterial imaging and defined as revised arterial occlusive lesion scores of 2b to 3. The association between transportation mode (helicopter versus ground) and interhospital recanalization was studied in logistic regression analysis, adjusting for pretransfer IVT use, occlusion site, and transfer duration. RESULTS:Among 520 included patients, 315 (61%) were transferred by helicopter and 259 (50%) received IVT before transfer. Interhospital recanalization rates were similar between helicopter and ground transfers in both the overall cohort (23% versus 19%; P=0.30) and the IVT subgroup (36% versus 33%; P=0.61). Adjusted analyses confirmed no association between helicopter transport and interhospital recanalization (adjusted odds ratio, 1.23 [95% CI, 0.72-2.11]; P=0.44). Favorable 3-month functional outcome (modified Rankin Scale score, 0-2) rates were also similar between helicopter and ground transfers in both unadjusted (35% versus 40%; P=0.29) and adjusted analyses (adjusted odds ratio, 1.12 [95% CI, 0.67-1.88]; P=0.67). CONCLUSIONS:In this multicenter observational cohort study, helicopter transfer was not associated with improved interhospital recanalization or favorable functional outcomes compared with ground transport. These findings do not support the hypothesis that vibrations during helicopter transport enhance IVT efficacy.

Introduction: Non-contrast brain CT hypodensity and volume in acute ischemic stroke patients are associated with poor patient outcomes. Currently, abnormal hypodensities in CT are measured using coregistered CT Perfusion or DWI based region of interest (ROI) segmentations. We hypothesized that deep learning based ischemic lesion segmentation on admission CT (DLCT) could serve as an alternative to CTP or DWI ROIs for density and volume measurements in CT. Methods: Patients from the prospective CRISP 2 study with admission CT/CTP in the primary stroke center and DWI after transfer to a comprehensive stroke center were included (n=208). We trained a deep learning model for admission CT ischemic lesion segmentation using DEFUSE 3 patients (n=218). Besides this DLCT ROI, we used the admission CTP ischemic core (relative cerebral blood flow <30%) and manually segmented DWI lesion co-registered to the CT space. We report Bland-Altman analyses with mean difference between ROI methods and 95% confidence intervals (mean[95%CI]) for the following measurements: total volume, volume with <26 Hounsfield units (HU) and >26HU, volume with >10% and >20% relative hypodense voxels, average (avg), median, and standard deviation of density (HU) in the ROI, net water uptake (NWU=[1-mean density ischemic/contralateral ROI]), proportion of the total lesion with >10% and >20% relative hypodense voxels. Relative hypodensity was measured as the percentage difference between ischemic and contralateral voxels. Results: Mean differences for volume measures varied considerably for DLCT-CTP (total volume 1.6mL [-54.8;61.6]); volume<26HU 1.3mL [-16.5;19.0]), DLCT-DWI (total volume -22.0mL [-114.5; 70.6]; volume<26HU -3.0mL [-19.9; 13.9]), and CTP-DWI (total volume -23.6mL [100.6; 53.4]; volume<26HU -4.3mL [-22.4; 13.9]). However, DLCT-DWI and CTP-DWI had similar differences. Contrary to volume measure, average density and net water uptake measures had lower differences between DLCT-CTP (avg: -0.7HU [-5.1; 3.8]; NWU: 3% [-9;15]), DLCT-DWI (avg: -1.6HU [-6.8; 3.6]; NWU: 5% [-7; 18]), and CTP-DWI (avg: -1.6HU [-4.8; 1.7]; NWU: 2% [-8; 11]). Figure 2 describes all other variables. Conclusion: DLCT, CTP, and DWI techniques demonstrate relatively low mean differences for volume and hypodensity measurements, but substantial variability is present despite this agreement on average. Further research should identify if these variations alter associations with clinical outcomes.

Background CT perfusion (CTP)-derived baseline ischemic core volume (ICV) can overestimate the true extent of infarction, which may result in exclusion of patients with ischemic stroke from endovascular treatment (EVT). Purpose To determine whether ischemic core overestimation is associated with larger ICV and degree of recanalization. Materials and Methods This retrospective multicenter cohort study included patients with acute ischemic stroke triaged at multimodal CT who underwent EVT between January 2015 and January 2022. The primary outcome was ischemic core overestimation, which was assumed when baseline CTP-derived ICV was larger than the final infarct volume at follow-up imaging. The secondary outcome was functional independence defined as modified Rankin Scale scores of 0-2 90 days after EVT. Successful vessel recanalization was defined as extended Thrombolysis in Cerebral Infarction score of 2b or higher. Categorical variables were compared between patients with ICV of 50 mL or less versus large ICV greater than 50 mL with use of the χ2 test. Adjusted multivariable logistic regression analyses were used to assess the primary and secondary outcomes. Results In total, 721 patients (median age, 76 years [IQR, 64-83 years]; 371 female) were included, of which 162 (22%) demonstrated ischemic core overestimation. Core overestimation occurred more often in patients with ICV greater than 50 mL versus 50 mL or less (48% vs 16%; P < .001) and those with successful versus unsuccessful vessel recanalization (26% vs 13%; P < .001). In an adjusted model, successful recanalization after EVT (odds ratio [OR], 3.14 [95% CI: 1.65, 5.95]; P < .001) and larger ICV (OR, 1.03 [95% CI: 1.02, 1.04]; P < .001) were independently associated with core overestimation, while the time from symptom onset to imaging showed no association (OR, 0.99; P = .96). Core overestimation was independently associated with functional independence (adjusted OR, 2.83 [95% CI: 1.66, 4.81]; P < .001) after successful recanalization. Conclusion Ischemic core overestimation occurred more frequently in patients presenting with large CTP-derived ICV and successful vessel recanalization compared with those with unsuccessful recanalization. © RSNA, 2024 Supplemental material is available for this article.

The polycystic kidney disease gene product polycystin-2 (PC2) localizes to and is released from primary cilia in extracellular vesicles (EVs). We report that KIF13B regulates ciliary EV release and PC2 levels in kidney epithelial cells in a time-dependent manner and show that KIF13B itself is released from the ciliary tip. In early stages of ciliation, Kif13b -/- cells displayed excessive ciliary accumulation of PC2 and initially released fewer small EVs than control cells. Over time, ciliated Kif13b -/- cells increased their small EV release rate to control levels, however proteomic analysis identified >50 proteins depleted from mutant EV samples. These included the ubiquitin E3 ligase ITCH and palmitoyl transferase ZDHHC5, which localized to primary cilia. Mature Kif13b -/- cilia exhibited aberrant membrane bulges and decreased PC2 and ALIX, an ITCH substrate that negatively regulated ciliary PC2 levels. Our work provides new insight into the mechanisms of ciliary EV release, which is important for regulating ciliary membrane homeostasis and signalling function. ### Competing Interest Statement The authors have declared no competing interest.

Background Deep venous outflow (VO) may be an important surrogate marker of collateral blood flow in acute ischemic stroke patients with a large vessel occlusion (AIS-LVO). Researchers have yet to determine the relationship between deep VO status in late-window patients and imaging measures of collaterals, which are key in preserving tissue. Materials and Methods We performed a multicenter retrospective cohort study on a subset of DEFUSE 3 patients recruited across 38 centers between May 2016 and May 2017 who underwent successful thrombectomy revascularization. Internal cerebral vein opacification was scored on a scale of 0–2. This metric was added to the cortical vein opacification score to derive the comprehensive VO (CVO) score from 0 to 8. Patients were stratified by favorable (ICV+) and unfavorable (ICV−) ICV scores, and similarly CVO+ and CVO−. Analyses comparing outcomes were primarily conducted by Mann–Whitney U and χ2 tests. Results Forty-five patients from DEFUSE 3 were scored and dichotomized into CVO+, CVO−, ICV+, and ICV− categories, with comparable demographics. Hypoperfusion intensity ratio, a marker of tissue level collaterals, was significantly worse in the ICV− and CVO− groups (p = 0.005). ICV− alone was also associated with a larger perfusion lesion (138 ml vs 87 ml; p = 0.023). No significant differences were noted in functional and safety outcomes. Conclusions Impaired deep venous drainage alone may be a marker of poor tissue level collaterals and a greater degree of affected tissue in AIS-LVO patients presenting in the late-window who subsequently undergo successful revascularization.

Background: Ischemic stroke patients who are eligible for endovascular therapy (EVT), can be transferred from a primary stroke center (PSC) to an EVT-capable comprehensive stroke center (CSC). Little is known about the dynamics of the collateral circulation in this time-window. We aimed to explore changes in collateral status during inter-hospital transfer among patients with poor collaterals on presentation to the PSC. Methods: Data from patients with an anterior circulation large vessel occlusion (LVO), transferred to two CSCs were prospectively collected. A CT perfusion was obtained at the PSC followed by an MRI immediately on arrival at the CSC. The hypoperfusion intensity ratio (HIR), a measure of collateral blood flow, was calculated as the ratio of the Tmax volumes of >10s and >6s. Only patients with stable LVO at the CSC and poor collateral status at the PSC (HIR ≥ 0.40) were included. An HIR < 0.40 in the CSC and a difference ≥ 0.10 was considered as HIR improvement. Results: Data from 104 patients with perfusion imaging at both PSC and CSC, were analyzed. Of them, we included 59 patients with an HIR ≥ 0.40 at the PSC. Sixteen (27%) patients experienced HIR improvement during transfer (Figure 1) . A smaller baseline core volume was independently associated with HIR improvement (OR for every 10 ml increase = 0.46 {95%CI 0.21-0.81}; p=0.03). Collateral improvement was associated with slower infarct growth during transfer (2.45 {95%CI 1.03-3.62} vs 7.77 {95%CI 4.56-17.86} ml/h; p<0.01) and a better functional outcome at 90 days post stroke (median mRS 3 {IQR 1-5} vs 4 {IQR 4-6}; p=0.01). Conclusion: During inter-hospital transfer spontaneous improvement in collateral status, as measured by HIR, is commonly seen, and associated with a smaller infarct core at the PSC, slower infarct growth during transfer, and better functional outcomes. Future neuroprotective trials targeted at collateral improvement, might consider the use of the HIR change as a surrogate outcome marker.

Polarized vesicular trafficking directs specific receptors and ion channels to cilia, but the underlying mechanisms are poorly understood. Here we describe a role for DLG1, a core component of the Scribble polarity complex, in regulating ciliary protein trafficking in kidney epithelial cells. Conditional knockout of Dlg1 in mouse kidney caused ciliary elongation and cystogenesis, and cell-based proximity labelling proteomics and fluorescence microscopy showed alterations in the ciliary proteome upon loss of DLG1. Specifically, the retromer-associated protein SDCCAG3, IFT20 and polycystin-2 (PC2) were reduced in cilia of DLG1 deficient cells compared to control cells. This phenotype was recapitulated in vivo and rescuable by re-expression of wildtype DLG1, but not a Congenital Anomalies of the Kidney and Urinary Tract (CAKUT)-associated DLG1 variant, p.T489R. Finally, biochemical approaches and Alpha Fold modelling suggested that SDCCAG3 and IFT20 form a complex that associates, at least indirectly, with DLG1. Our work identifies a key role for DLG1 in regulating ciliary protein composition and suggests that ciliary dysfunction of the p.T489R DLG1 variant may contribute to CAKUT.

Ciliopathies are genetic disorders caused by defects in the structure or function of the cilia and their related structures. Bardet-Biedl syndrome (BBS) is a complex ciliopathy with varied symptoms, probably due to altered membrane receptor signalling pathways. This study explores the role of BBS1 and BBS4 gene deficiencies in receptor trafficking and epithelial-mesenchymal transition (EMT) in retinal epithelial cells. Deficiencies in these genes, key components of the BBSome complex, led to shorter cilia and disrupted receptor endocytosis. BBS1 knockout (KO) cells showed delayed transferrin internalisation and increased recycling of TGFBR1, promoting EMT. On the contrary, BBS4 KO cells had higher receptor degradation but no affected recycling. These disruptions suggest that BBSome regulates both ciliary and nonciliary pathways. Increased EMT markers in BBS1 KO cells were associated with higher cell migration and reduced proliferation, highlighting the role in receptor trafficking and potential therapeutic targets for retinal degeneration in BBS. ### Competing Interest Statement The authors have declared no competing interest.

BACKGROUND:Patients with acute ischemic stroke harboring a large vessel occlusion admitted to nonendovascular-capable centers often require interhospital transfer for thrombectomy. We evaluated the incidence and predictors of arterial recanalization during transfer, as well as the relationship between interhospital recanalization and clinical outcomes. METHODS:We analyzed data from 2 cohorts of patients with an anterior circulation large vessel occlusion transferred for consideration of thrombectomy to a comprehensive center, with arterial imaging at the referring hospital and on comprehensive stroke center arrival. Interhospital recanalization was determined by comparison of the baseline and posttransfer arterial imaging and was defined as revised arterial occlusive lesion (rAOL) score 2b to 3. Pretransfer variables independently associated with interhospital recanalization were studied using multivariable logistic regression analysis. RESULTS:Of the 520 included patients (Montpellier, France, n=237; Stanford, United States, n=283), 111 (21%) experienced interhospital recanalization (partial [rAOL=2b] in 77% and complete [rAOL=3] in 23%). Pretransfer variables independently associated with recanalization were intravenous thrombolysis (adjusted odds ratio, 6.8 [95% CI, 4.0-11.6]), more distal occlusions (intracranial carotid occlusion as reference: adjusted odds ratio, 2.0 [95% CI, 0.9-4.5] for proximal first segment of the middle cerebral artery, 5.1 [95% CI, 2.3-11.5] for distal first segment of the middle cerebral artery, and 5.0 [95% CI, 2.1-11.8] for second segment of the middle cerebral artery), and smaller clot burden (clot burden score 0-4 as reference: adjusted odds ratio, 3.4 [95% CI, 1.5-7.6] for 5-7 and 5.6 [95% CI, 2.4-12.7] for 8-9). Recanalization on arrival at the comprehensive center was associated with less interhospital infarct growth (rAOL, 0-2a: 11.6 mL; rAOL, 2b: 2.2 mL; rAOL, 3: 0.6 mL; Ptrend<0.001) and greater interhospital National Institutes of Health Stroke Scale score improvement (0 versus -5 versus -6; Ptrend<0.001). Interhospital recanalization was associated with reduced 3-month disability (adjusted common odds ratio, 2.51 [95% CI, 1.68-3.77]) with greater benefit from complete than partial recanalization. CONCLUSIONS:Recanalization is frequently observed during interhospital transfer for thrombectomy and is strongly associated with favorable outcomes, even when partial. Broadening thrombolysis indications in primary centers, and developing therapies that increase recanalization during transfer, will likely improve clinical outcomes.

BACKGROUND:In patients with an acute ischemic stroke, the penumbra is defined as ischemic tissue that remains salvageable when reperfusion occurs. However, the expected clinical recovery congruent with penumbral salvage is not always observed. AIMS:We aimed to determine whether the magnetic resonance imaging (MRI)-defined penumbra includes irreversible neuronal loss that impedes expected clinical recovery after reperfusion. METHODS:In the prospective French Acute Multimodal Imaging Study to Select Patients for Mechanical Thrombectomy (FRAME) and an observational cohort of patients with large vessel occlusions undergoing endovascular treatment, we quantified penumbral integrity by fluid-attenuated inversion recovery (FLAIR) changes. We studied the influence of recanalization status on the evolution of penumbral FLAIR changes and studied penumbral FLAIR changes as predictor of tissue fate and functional outcome on the 90-day modified Rankin Scale (mRS). RESULTS:Recanalization status did not modify the evolution of rFLAIR signal intensity (SI) over time in the total cohort, but was associated with lower SI in the FRAME subset (b = -0.06, p for interaction = 0.04). Median rFLAIR SI was higher at baseline in the subsequently infarcted penumbra compared to the salvaged (ratio = 1.07, standard deviation (SD) = 0.07 vs 1.03, SD = 0.06 p < 0.0001, n = 150). The severity and extent of rFLAIR SI changes did not predict 90-day functional outcome in univariate (p = 0.09) and multivariate logistic regression (p = 0.4). CONCLUSIONS:Recanalization status did not influence the evolution of penumbral FLAIR changes. FLAIR SI changes in the baseline penumbra were associated with tissue fate, but not functional outcome.

Transforming Growth Factor-Beta-Activated Kinase 1 (TAK1/MAP3K7), along with its upstream regulators TAK1-Binding Protein 2 (TAB2) and the catalytic alpha-subunit of Protein Kinase A (PKA-Cα/PRKACA), has been identified as a pivotal player in regulation of developmental processes. Haploinsufficiency of TAB2 causes Congenital Heart Disease (CHD) and rare variants in PKA-Cα and TAK1 cause cardioacrofacial dysplasia (CAFD), and Frontometaphyseal Dysplasia (FMD) and cardiospondylocarpofacial syndrome (CSCFS), respectively, rare multisystem syndromes, where CHD may appear in the clinical spectrum. We hypothesized that TAK1 plays a significant role in heart development and CHD and addressed this by genetic analysis in CHD patient cohorts and experiments in cell and animal models. Exome sequencing data from 1,471 CHD patients with extracardiac anomalies (syndromic CHD, sCHD), 2,405 patients with nonsyndromic CHD (nsCHD) and 45,082 controls showed increased burden of rare TAB2 and TAK1 variants in sCHD, but not in nsCHD. Detailed characterization of tak1-/- and tab2-/- zebrafish mutants revealed cardiac defects (dilated atrium, trabeculation defects, tachycardia and reduced contractility) as well as extracardiac developmental anomalies. RNA sequencing of tak1-/- mutant hearts showed downregulation of genes encoding core cardiac transcription factors, sarcomeric proteins and extracellular matrix proteins. Experiments with cell cultures and analysis of zebrafish larvae and gastruloids indicated that TAK1 via TAB2 and PKA-Cα is activated at the primary cilium during cardiomyogenesis and that TAK1 activation at this site is enhanced by cardiomyogenic signaling molecules, including ligands of the TGFB/BMP superfamily. Consistent with these findings, CRISPR/Cas9-mediated editing of TAK1 or administration of small molecule inhibitors targeting TAK1 inhibited ciliary signaling and cardiomyocyte differentiation in vitro , while FMD-causing mutations in TAK1 reduced its ciliary localization. In conclusion, our data establishes a central role for TAK1 and its upstream regulators in cardiac development and syndromic CHD, coordinated via the primary cilium.### Competing Interest StatementThe authors have declared no competing interest.

AbstractBackgroundWhile advances in endovascular thrombectomy (EVT) have led to high reperfusion rates, most patients treated with EVT do not avoid disability. Post‐reperfusion hemorrhagic transformation (HT) is a potential target for improving outcomes. This study examined pretreatment blood–brain barrier (BBB) disruption in tissue that would subsequently become part of the final infarct to evaluate its role in post‐EVT HT.MethodsThis post hoc analysis of the FRAME study, which enrolled patients with anterior large vessel occlusion who received EVT within 6 hours of onset, included patients if they had successful pretreatment MRI perfusion weighted imaging (PWI) and underwent successful EVT. BBB disruption was measured as the percent signal change due to gadolinium leakage on the PWI source images prior to thrombectomy. Mean permeability derangement (MPD) was defined as the average of all voxels in the stroke core that are two standard deviations above normal. The primary outcome was hemorrhagic transformation with parenchymal hematoma (PH).ResultsIn total, 164 patients were included; mean age was 71 and 48% were female. PH occurred in 57 patients. Median MPD was 13.5% for patients with PH versus 3.6% for patients without (p < 0.0001). Elevated MPD was independently associated with PH with a 20% increased risk of PH for each 5% increase in MPD (OR 1.206; 95% CI 1.037:1.405; p = 0.0147, adjusted for NIHSS and procedure duration).ConclusionsEven in patients who are successfully recanalized in an early time window, pretreatment BBB disruption in regions that go on to infarct is associated with an increased risk of post‐EVT HT.

Background: Patients with acute ischemic stroke harboring a large vessel occlusion (LVO) admitted to non endovascular-capable centers often require inter-hospital transfer for thrombectomy. We aimed to describe the incidence of substantial clinical change during transfer, the clinical and imaging factors associated with change, and its relationship with 3-month outcome. Methods: We analyzed data from two prospectively collected cohorts of acute stroke patients transferred for thrombectomy to a comprehensive center (Stanford, USA, Nov 2019-Jan 2023; Montpellier, France, Jan 2015-Jan 2017). Patients were included if they had evidence of an LVO at the referring hospital and had an NIHSS score documented before and immediately after transfer. Inter-hospital clinical change was categorized as improvement (>=4 points and >=25% decrease between the NIHSS score in the referring hospital and upon comprehensive center arrival), deterioration (>=4 points and >=25% increase), or stability (neither improvement nor deterioration). The stable group was considered as the reference, and was compared to the improvement or deterioration groups separately. Results: A total of 504 patients were included, of whom 22% experienced inter-hospital improvement, 14% deterioration, and 64% were stable. Pre-transfer variables independently associated with clinical improvement were intravenous thrombolysis use, more distal occlusions, and lower serum glucose; variables associated with deterioration included more proximal occlusions and higher serum glucose. On post-transfer imaging, clinical improvement was associated with arterial recanalization and smaller infarct growth; and deterioration with larger infarct growth. As compared to stable patients, those with clinical improvement had better 3-month functional outcome (adjusted common OR=2.39; 95%CI=1.57-3.64), while those with deterioration had worse outcome (adjusted common OR=0.56, 95%CI=0.34-0.92). Conclusion: Substantial inter-hospital clinical changes are frequently observed in LVO-related ischemic strokes, with significant impact on functional outcome. There is a need to develop treatments that improves the clinical status during transfer.

Gain-of-function variants in GFAP leads to protein aggregation and is the cause of the severe neurodegenerative disorder Alexander Disease (AxD), while loss of GFAP function has been considered benign. Here, we investigated a six-generation family, where multiple individuals presented with gliosis of the optic nerve head and visual impairment. Whole genome sequencing (WGS) revealed a frameshift variant in GFAP (c.928dup, p.(Met310Asnfs*113)) segregating with disease. Analysis of human embryonic tissues revealed strong expression of GFAP in retinal neural progenitors. A zebrafish model verified that c.928dup does not result in extensive GFAP protein aggregation and zebrafish gfap loss-of-function mutants showed vision impairment and retinal dysplasia, characterized by a significant loss of M & uuml;ller glia cells and photoreceptor cells. Our findings show how different mutational mechanisms can cause diverging phenotypes and reveal a novel function of GFAP in vertebrate eye development.