Mechanical thrombectomy practices in France: Exhaustive survey of centers and individual operators.

BACKGROUND AND PURPOSE: Mechanical thrombectomy (MT) has dramatically changed the landscape of stroke care as well as stroke care organization. Public health institutions are faced with the challenge of swiftly providing equal access to this high technical level procedure with rapidly broadening indications, and constantly developing techniques. The aim of this study was to present a current nationwide overview of technical MT practices in France as well as local organizations. MATERIALS AND METHODS: Thrombectomy capable French stroke centers, and physicians performing MT were invited to participate to a nationwide survey, disseminated through an existing trainee-led research network (the JENI-RC) under the aegis of the French Society of Neuroradiology. The survey was composed of 64 questions to collect both individual practices and general center-based information. RESULTS: All French centers (100%) answered the survey, and 74% (110/148) of active interventional neuroradiologists (INR) performing MT completed individual questionnaires. The mean number of INR per center performing MT was 3.7±1.85, and 85% of the centers were organized for 24/7 continuity of care. MRI was the most commonly used imaging modality for stroke diagnosis and patients' selection, and perfusion imaging was routinely available in 85% of the centers. Half of centers performed yearly between 100 and 200 MT. Anesthesiologic, and technical considerations are also developed in the manuscript. CONCLUSIONS: This nationwide survey highlights the impressive response to the challenge of reorganization of stroke care with regards to mechanical thrombectomy in France. Technical and management disparities remain. Most centers remain understaffed to properly function in the long term, but the inflow of INT trainees is substantial.

Epidermal growth factor-induced vacuolar (H+)-atpase assembly: a role in signaling via mTORC1 activation.

Using proteomics and immunofluorescence, we demonstrated epidermal growth factor (EGF) induced recruitment of extrinsic V(1) subunits of the vacuolar (H(+))-ATPase (V-ATPase) to rat liver endosomes. This was accompanied by reduced vacuolar pH. Bafilomycin, an inhibitor of V-ATPase, inhibited EGF-stimulated DNA synthesis and mammalian target of rapamycin complex 1 (mTORC1) activation as indicated by a decrease in eukaryotic initiation factor 4E-binding 1 (4E-BP1) phosphorylation and p70 ribosomal S6 protein kinase (p70S6K) phosphorylation and kinase activity. There was no corresponding inhibition of EGF-induced Akt and extracellular signal-regulated kinase (Erk) activation. Chloroquine, a neutralizer of vacuolar pH, mimicked bafilomycin effects. Bafilomycin did not inhibit the association of mTORC1 with Raptor nor did it affect AMP-activated protein kinase activity. Rather, the intracellular concentrations of essential but not non-essential amino acids were decreased by bafilomycin in EGF-treated primary rat hepatocytes. Cycloheximide, a translation elongation inhibitor known to augment intracellular amino acid levels, prevented the effect of bafilomycin on amino acids levels and completely reversed its inhibition of EGF-induced mTORC1 activation. In vivo administration of EGF stimulated the recruitment of Ras homologue enriched in brain (Rheb) but not mammalian target of rapamycin (mTOR) to endosomes and lysosomes. This was inhibited by chloroquine treatment. Our results suggest a role for vacuolar acidification in EGF signaling to mTORC1.

Functional outcome in low-ASPECTS (0-5) acute ischemic stroke treated with mechanical thrombectomy: impact of laterality explored in a single-center study.

Background: There is no consensus regarding the influence of infarct laterality in patients with acute ischemic stroke due to anterior large vessel occlusion (AIS-LVO) treated with mechanical thrombectomy (MT), particularly in low-ASPECT (0-5) patients who were excluded from the initial MT studies and that participated in dedicated randomized-controlled trials that do not consider the side of the occlusion. We aimed to evaluate the role of infarct laterality on the clinical outcome in low-ASPECT AIS patients treated with MT. Material and methods: We retrospectively analyzed our institutional stroke database in our Thrombectomy-Capable Stroke Center (TCSC), including patient characteristics, procedural variables, and outcomes, between January 2015 and January 2022. Patients with acute intracranial ICA and/or proximal MCA occlusions with ASPECT ≤ 5 either on CT or MRI were included and divided into 2 groups according to the location of ischemia. The primary endpoint was a good clinical outcome at 90 days (modified Rankin Scale (mRS) score of 0-3). Results: Between January 2015 and November 2021, 817 MT were performed, of which 82 were low-ASPECT (10.0%): 41 left-sided and 41 right-sided strokes. The rates of good clinical outcome were 30.8% (12/41) for the left-sided group and 43.6% (17/41) for the right-sided group, with a p-value of 0.349. The morality rate showed no significant difference between the two groups: 39.0% (16/41) in the right stroke group and 36.6% (15/41) in the left stroke group. Conclusion: The clinical outcome was not significantly influenced by stroke laterality. The results of this single-center retrospective study indicate either a lack of strength or equal value in performing mechanical thrombectomy regardless of stroke laterality.

Antithrombotic therapies for neurointerventional surgery: a 2021 French comprehensive national survey.

BACKGROUND: Neurointerventionists lack guidelines for the use of antithrombotic therapies in their clinical practice; consequently, there is likely to be significant heterogeneity in antithrombotic use between centers. Through a nationwide survey, we aimed to obtain an exhaustive cross-sectional overview of antithrombotic use in neurointerventional procedures in France. METHODS: In April 2021, French neurointerventional surgery centers were invited to participate in a nationwide 51-question survey disseminated through an active trainee-led research collaborative network (the JENI-RC). RESULTS: All 40 centers answered the survey. Fifty-one percent of centers reported using ticagrelor and 43% used clopidogrel as premedication before intracranial stenting. For flow diversion treatment, dual antiplatelet therapy was maintained for 3 or 6 months in 39% and 53% of centers, respectively, and aspirin was prescribed for 12 months or more than 12 months in 63% and 26% of centers, respectively. For unruptured aneurysms, the most common heparin bolus dose was 50 IU/kg (59%), and only 35% of centers monitored heparin activity for dose adjustment. Tirofiban was used in 64% of centers to treat thromboembolic complications. Fifteen percent of these comprehensive stroke centers reported using tenecteplase to treat acute ischemic strokes. Cangrelor appeared as an emergent drug in specific indications. CONCLUSION: This nationwide survey highlights the important heterogeneity in clinical practices across centers. There is a pressing need for trials and guidelines to further evaluate and harmonize antithrombotic regimens in the neurointerventional field.

Carotid artery direct access for mechanical thrombectomy: the Carotid Artery Puncture Evaluation (CARE) study.

BACKGROUND: In acute ischemic stroke due to anterior large vessel occlusion (AIS-LVO), accessing the target occluded vessel for mechanical thrombectomy (MT) is sometimes impossible through the femoral approach. We aimed to evaluate the safety and efficacy of direct carotid artery puncture (DCP) for MT in patients with failed alternative vascular access. METHODS: We retrospectively analyzed data from 45 stroke centers in France, Switzerland and Germany through two research networks from January 2015 to July 2019. We collected physician-centered data on DCP practices and baseline characteristics, procedural variables and clinical outcome after DCP. Uni- and multivariable models were conducted to assess risk factors for complications. RESULTS: From January 2015 to July 2019, 28 149 MT were performed, of which 108 (0.39%) resulted in DCP due to unsuccessful vascular access. After DCP, 77 patients (71.3%) had successful reperfusion (modified Thrombolysis In Cerebral Infarction (mTICI) score ≥2b) and 28 (25.9%) were independent (modified Rankin Scale (mRS) score 0-2) at 3 months. 20 complications (18.5%) attributed to DCP occurred, all of them during or within 1 hour of the procedure. Complications led to extension of the intubation time in the intensive care unit in 7 patients (6.4%) and resulted in death in 3 (2.8%). The absence of use of a hemostatic closure device was associated with a higher complication risk (OR 3.04, 95% CI 1.03 to 8.97; p=0043). CONCLUSION: In this large multicentric study, DCP was scantly performed for vascular access to perform MT (0.39%) in patients with AIS-LVO and had a high rate of complications (18.5%). Our results provide arguments for not closing the cervical access by manual compression after MT.

Regulation of hepatic insulin-like growth factor-binding protein-1 gene expression by insulin: central role for mammalian target of rapamycin independent of forkhead box O proteins.

The expression of IGF-binding protein-1 (IGFBP-1) is induced in rat liver by dexamethasone and glucagon and is completely inhibited by 100 nM insulin. Various studies have implicated phosphatidylinositol 3-kinase, protein kinase B (Akt), phosphorylation of the transcription factors forkhead in rhabdomyosarcoma 1 (Foxo1)/Foxo3, and the mammalian target of rapamycin (mTOR) in insulin's effect. In this study we examined insulin regulation of IGFBP-1 in both subconfluent and confluent hepatocytes. In subconfluent hepatocytes, insulin inhibition of IGFBP-1 mRNA levels was blocked by inhibiting PI3 kinase activation, and there was a corresponding inhibition of Foxo1/Foxo3 phosphorylation. In these same cells, inhibition of the insulin effect by rapamycin occurred in the presence of insulin-induced Foxo1/Foxo3 phosphorylation. In confluent hepatocytes, insulin could not activate the phosphatidylinositol 3-kinase (PI3 kinase)-Akt-Foxo1/Foxo3 pathway, but still inhibited IGFBP-1 gene expression in an mTOR-dependent manner. In subconfluent hepatocytes, the serine/threonine phosphatase inhibitor okadaic acid (100 nM) partially inhibited IGFBP-1 gene expression by 40%, but did not produce phosphorylation of either Akt or Foxo proteins. In contrast, 1 nm insulin inhibited the IGFBP-1 mRNA level by 40% and correspondingly activated Akt and Foxo1/Foxo3 phosphorylation to a level comparable to that observed with 100 nM insulin. These results suggest a potential role for a serine/threonine phosphatase(s) in the regulation of IGFBP-1 gene transcription, which is not downstream of mTOR and is independent of Akt. In conclusion, we have found that in rat liver, insulin inhibition of IGFBP-1 mRNA levels can occur in the absence of the phosphorylation of Foxo1/Foxo3, whereas activation of the mTOR pathway is both necessary and sufficient.

The G protein-coupled receptor kinase-2 is a TGFbeta-inducible antagonist of TGFbeta signal transduction.

Signaling from the activin/transforming growth factor beta (TGFbeta) family of cytokines is a tightly regulated process. Disregulation of TGFbeta signaling is often the underlying basis for various cancers, tumor metastasis, inflammatory and autoimmune diseases. In this study, we identify the protein G-coupled receptor kinase 2 (GRK2), a kinase involved in the desensitization of G protein-coupled receptors (GPCR), as a downstream target and regulator of the TGFbeta-signaling cascade. TGFbeta-induced expression of GRK2 acts in a negative feedback loop to control TGFbeta biological responses. Upon TGFbeta stimulation, GRK2 associates with the receptor-regulated Smads (R-Smads) through their MH1 and MH2 domains and phosphorylates their linker region. GRK2 phosphorylation of the R-Smads inhibits their carboxyl-terminal, activating phosphorylation by the type I receptor kinase, thus preventing nuclear translocation of the Smad complex, leading to the inhibition of TGFbeta-mediated target gene expression, cell growth inhibition and apoptosis. Furthermore, we demonstrate that GRK2 antagonizes TGFbeta-induced target gene expression and apoptosis ex vivo in primary hepatocytes, establishing a new role for GRK2 in modulating single-transmembrane serine/threonine kinase receptor-mediated signal transduction.

Effect of inhibiting vacuolar acidification on insulin signaling in hepatocytes.

Previous studies have shown that the endosomal apparatus plays an important role in insulin signaling. Inhibition of endosomal acidification leads to a decrease in insulin-insulin receptor kinase (IRK) dissociation and insulin degradation. Thus, vacuolar pH could function as a modulator of insulin signaling in endosomes. In the present study we show that in primary hepatocytes pretreated with bafilomycin, there is an inhibition of vacuolar acidification. Incubation of these cells with insulin was followed by an augmentation of IRK activity but an inhibition of phosphatidylinositol 3-kinase/Akt activity and a decrease in insulin-induced DNA and glycogen synthesis. Bafilomycin treatment inhibited IRK recycling to the plasma membrane without affecting IRK internalization. Impaired IRK recycling correlated with a decrease in insulin signaling. We suggest that inhibiting vacuolar acidification sequesters activated IRKs in an intracellular compartment(s) where signaling is inhibited. This implies that endosomal receptor trafficking plays a role in regulating signal transduction.

Epidermal growth factor-induced DNA synthesis. Key role for Src phosphorylation of the docking protein Gab2.

We have previously demonstrated that phosphatidylinositol 3-kinase (PI3-kinase) is necessary and sufficient to account for epidermal growth factor (EGF)-induced mitogenesis in rat primary hepatocytes. A cytosolic Gab2-containing complex accounts for >80% of the total EGF-induced PI3-kinase activity (Kong, M., Mounier, C., Wu, J., and Posner, B. I. (2000) J. Biol. Chem. 275, 36035-36042), suggesting a key role for Gab2 in EGF-induced mitogenesis. Here, we demonstrate that PP1, a selective inhibitor of Src family kinases, blocks the EGF-induced Gab2 tyrosine phosphorylation without inhibiting EGF-induced phosphorylation of the EGF receptor, ErbB3, or Shc. We also show that Gab2 phosphorylation is increased in Csk knockout cells in which Src family kinases are constitutively activated. Furthermore, PP1 blocks Gab2-associated downstream events including EGF-induced PI3-kinase activation, Akt phosphorylation, and DNA synthesis. We demonstrate that Gab2 and Src are constitutively associated. Since this association involves the proline-rich sequences of Gab2, it probably involves the Src homology 3 domain of Src kinase. Mutation of the proline-rich sequences in Gab2 prevented EGF-induced Gab2 phosphorylation, PI3-kinase/Akt activation, and DNA synthesis, demonstrating that Gab2 phosphorylation is critical for EGF-induced mitogenesis and is not complemented by ErbB3 or Shc phosphorylation. We also found that overexpression of a Gab2 mutant lacking SHP2 binding sites increased EGF-induced Gab2 phosphorylation and the activation of PI3-kinase but blocked activation of MAPK. In addition, we demonstrated that the Src-induced response was down-regulated by Gab2-associated SHP2. In summary, our results have defined the role for Src activation in EGF-induced hepatic mitogenesis through the phosphorylation of Gab2 and the activation of the PI3-kinase cascade.