Homocysteine concentration in coronary artery disease and severity of coronary lesions.

Our previous study reckons that the impact of the rs1801133 variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) on coronary artery disease (CAD) is possibly mediated by cardiometabolic disorder. This study is performed to verify this hypothesis. Four hundred and thirty CAD patients and 216 CAD-free individuals were enrolled in this case-control study. The rs1801133 variant was genotyped by PCR-RFLP. Severity of coronary lesions was evaluated by number of stenotic coronary vessels and extent of coronary stenosis. The rs1801133 T allele significantly increased homocysteine levels in patients with CAD and CAD-free individuals. Individuals with the T allele of rs1801133 had an increased risk of developing CAD. In contrast, individuals with the TT genotype of rs1801133 were at high risk of multiple vessel lesions. The carriers of CT genotype had higher levels of systolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C), and high-sensitivity C-reactive protein (hs-CRP), and lower levels of apolipoprotein A1 (APOA1) than those with CC genotype in male patients with CAD. The receiver operating characteristic (ROC) curve and precision-recall (PR) curve indicated that hyperhomocysteinemia was sensitive to predict the severity of CAD. Multivariate logistic regression revealed that homocysteine, rs1801133, age, smoking, weight, body mass index (BMI), lipoprotein(a) [Lp(a)], and hs-CRP were independent risk factors for CAD. The increased risk of CAD and severity of coronary lesions associated with rs1801133 in the Chinese Han population were attributed, at least partly, to high homocysteine levels. Hyperhomocysteinemia had a high predictive value for severe CAD or multiple vessel lesions.

Neurologic Effects of Gadolinium Retention in the Brain after Gadolinium-based Contrast Agent Administration.

Background Concerns over the neurotoxic potential of retained gadolinium in brain tissues after intravenous gadolinium-based contrast agent (GBCA) administration have led to pronounced worldwide use changes, yet the clinical sequelae of gadolinium retention remain undefined. Purpose To assess clinical and neurologic effects and potential neurotoxicity of gadolinium retention in rats after administration of various GBCAs. Materials and Methods From March 2017 through July 2018, 183 male Wistar rats received 20 intravenous injections of 2.5 mmol per kilogram of body weight (80 human equivalent doses) of various GBCAs (gadodiamide, gadobenate, gadopentetate, gadoxetate, gadobutrol, gadoterate, and gadoteridol) or saline over 4 weeks. Rats were evaluated 6 and 34 weeks after injection with five behavioral tests, and inductively coupled plasma mass spectrometry, transmission electron microscopy, and histopathology were performed on urine, serum, cerebrospinal fluid (CSF), basal ganglia, dentate nucleus, and kidney samples. Dunnett post hoc test and Wilcoxon rank sum test were used to compare differences between treatment groups. Results No evidence of differences in any behavioral test was observed between GBCA-exposed rats and control animals at either 6 or 34 weeks (P = .08 to P = .99). Gadolinium concentrations in both neuroanatomic locations were higher in linear GBCA-exposed rats than macrocyclic GBCA-exposed rats at 6 and 34 weeks (P < .001). Gadolinium clearance over time varied among GBCAs, with gadobutrol having the largest clearance (median: 62% for basal ganglia, 70% for dentate) and gadodiamide having no substantial clearance. At 34 weeks, gadolinium was largely cleared from the CSF and serum of gadodiamide-, gadobenate-, gadoterate-, and gadobutrol-exposed rats, especially for the macrocyclic agents (range: 70%-98% removal for CSF, 34%-94% removal for serum), and was nearly completely removed from urine (range: 96%-99% removal). Transmission electron microscopy was used to detect gadolinium foci in linear GBCA-exposed brain tissue, but no histopathologic differences were observed for any GBCA. Conclusion In this rat model, no clinical evidence of neurotoxicity was observed after exposure to linear and macrocyclic gadolinium-based contrast agents at supradiagnostic doses. © RSNA, 2022 Online supplemental material is available for this article.

Histological composition of retrieved emboli in acute ischemic stroke is independent of pre-thrombectomy alteplase use.

BACKGROUND AND PURPOSE: Given recent evidence suggesting the clot composition may be associated with revascularization outcomes and stroke etiology, clot composition research has been a topic of growing interest. It is currently unclear what effect, if any, pre-thrombectomy thrombolysis has on clot composition. Understanding this association is important as it is a potential confounding variable in clot composition research. We retrospectively evaluated the composition of retrieved clots from ischemic stroke patients who did and did not receive pre-treatment tPA to study the effect of tPA on clot composition. MATERIALS AND METHODS: Consecutive patients enrolled in the Stroke Thromboembolism Registry of Imaging and Pathology (STRIP) were included in this study. All patients underwent mechanical thrombectomy and retrieved clots were sent to a central core lab for processing. Histological analysis was performed using Martius Scarlett Blue (MSB) staining and area of the clot was also measured on the gross photos. Student's t test was used for continuous variables and chi-squared test for categorical variables. RESULTS: A total of 1430 patients were included in this study. Mean age was 68.4±13.5 years. Overall rate of TICI 2c/3 was 67%. A total of 517 patients received tPA (36%) and 913 patients did not (64%). Mean RBC density for the tPA group was 42.97±22.62% compared to 42.80±23.18% for the non-tPA group (P=0.89). Mean WBC density for the tPA group was 3.74±2.60% compared to 3.42±2.21% for the non-tPA group (P=0.012). Mean fibrin density for the tPA group was 26.52±15.81% compared to 26.53±15.34% for the non-tPA group (P=0.98). Mean platelet density for the tPA group was 26.22±18.60% compared to 26.55±19.47% for the non-tPA group (P=0.75). tPA group also had significantly smaller clot area compared to non-tPA group. CONCLUSIONS: Our study 1430 retrieved emboli and ischemic stroke patients shows no interaction between tPA administration and clot composition. These findings suggest that tPA does not result in any histological changes in clot composition.

Platelet-Rich Emboli in Cerebral Large Vessel Occlusion Are Associated With a Large Artery Atherosclerosis Source.

Background and Purpose- Nearly 30% of large vessel occlusion acute ischemic stroke clots are from an unknown source. We assessed histological clot composition in a series of patients with large vessel occlusion and investigated correlations between clot composition and stroke pathogenesis. Methods- As part of the multi-institutional STRIP registry (Stroke Thromboembolism Registry of Imaging and Pathology), consecutive emboli retrieved during mechanical thrombectomy were stained using Martius Scarlett Blue and analyzed using machine learning software. We assessed proportions of red blood cells, fibrin, platelets, and white blood cells. Correlations between clot components and stroke pathogenesis (large artery atherosclerosis, cardioembolism, and stroke of undetermined pathogenesis) were assessed using SPSS22. Results- One hundred five patients were included. The proportion of platelet-rich clots (55.0% versus 21.2%; P=0.005) and percentage of platelet content (22.1±4.2% versus 13.9±14.2%; P=0.03) was significantly higher in the large artery atherosclerosis group compared with the cardioembolic group. The proportion of platelet-rich clots (50.0% versus 21.2%; P=0.024) was also significantly higher in the cryptogenic group compared with cardioembolic cases. Large artery atherosclerosis and cryptogenic cases had a similar proportion of platelet-rich clots (55.0% versus 50.0%; P=0.636). There was no significant difference between stroke pathogenesis and the other major clot components. Conclusions- High platelet content of emboli is associated with a large artery atherosclerosis etiology of large vessel occlusion.

Comparison of Gadolinium Concentrations within Multiple Rat Organs after Intravenous Administration of Linear versus Macrocyclic Gadolinium Chelates.

Purpose To compare gadolinium tissue concentrations of multiple linear and macrocyclic chelates in a rat model to better understand the scope and extent of tissue deposition following multiple intravenous doses of gadolinium-based contrast agent (GBCA). Materials and Methods In this Institutional Animal Care and Use Committee-approved study, healthy rats received 20 intravenous injections of 2.5 mmol gadolinium per kilogram (gadolinium-exposed group) or saline (control group) over a 26-day period. Unenhanced T1 signal intensities of the dentate nucleus were measured from magnetic resonance (MR) images obtained prior to GBCA injection and 3 days after final injection. Rat brain and renal, hepatic, and splenic tissues were harvested 7 days after final injection and subjected to inductively coupled plasma mass spectrometry and transmission electron microscopy for quantification and characterization of gadolinium deposits. Results Gadolinium deposition in brain tissue significantly varied with GBCA type (F = 31.2; P < .0001), with median concentrations of 0 µg gadolinium per gram of tissue (95% confidence interval [CI]: 0, 0.2) in gadoteridol-injected rats, 1.6 µg gadolinium per gram of tissue (95% CI: 0.9, 4.7) in gadobutrol-injected rats, 4.7 µg gadolinium per gram of tissue (95% CI: 3.5, 6.1) in gadobenate dimeglumine-injected rats, and 6.9 µg gadolinium per gram of tissue (95% CI: 6.2, 7.0) in gadodiamide-injected rats; a significant positive dose-signal intensity correlation was identified (ρ = 0.93; P < .0001). No detectable neural tissue deposition or MR imaging signal was observed in control rats (n = 6). Similar relative differences in gadolinium deposition were observed in renal, hepatic, and splenic tissues at much higher tissue concentrations (P < .0001). Gadolinium deposits were visualized directly in the endothelial capillary walls and neural interstitium in GBCA-injected rats, but not in control rats. Conclusion Tissue deposition of gadolinium was two- to fourfold higher following administration of the linear agents gadodiamide and gadobenate dimeglumine compared with the macrocyclic agents gadobutrol and gadoteridol. These findings suggest that organ tissue deposition is reduced but not eliminated following administration of macrocyclic GBCA chelates in lieu of linear chelates. © RSNA, 2017 Online supplemental material is available for this article.

Cellular mechanisms of aneurysm occlusion after treatment with a flow diverter.

PURPOSE: To characterize the progression of healing across aneurysm necks following treatment with a flow diverter in a rabbit aneurysm model. MATERIALS AND METHODS: With institutional animal care and use committee approval, saccular aneurysms were created in 20 rabbits and treated with flow diverters. On days 1, 3, and 7 and weeks 4 and 8 after implantation, the aneurysm and the device-implanted vessel were harvested. En face staining of the gross specimen was performed for endothelial cells, endothelial progenitor cells, smooth muscle cells, and inflammatory cells. RESULTS: The parent artery segments covered by the flow diverters were completely devoid of endothelial cells at 1 and 3 days but had completely reendothelialized by 7 days. At all time points, the struts along the patent portions of the aneurysm necks harbored scattered tissue islands composed exclusively of inflammatory cells. At 4 and 8 weeks, all samples contiguous with the tissue along the parent arteries had translucent tissue present along the occluded segments of the aneurysm neck. The vast majority of endothelial cells were contiguous with the parent artery and had smooth muscle cells underlying them. Endothelial progenitor cells were not observed along the neck of any aneurysm. Aneurysm closure was noted only when complete or nearly complete endothelialization over the device struts was present. CONCLUSION: The initial event following flow diversion treatment is adherence of clusters of inflammatory cells across the aneurysm neck. Endothelialization is relatively delayed and derived exclusively from cells in the adjacent parent artery.

How the elastase-induced rabbit aneurysm heals following flow diverter treatment: a histopathological study.

OBJECTIVE: Fibrin deposition is integral to thrombus formation and wound healing. The role of fibrin deposition and subsequent metabolism following flow diversion for aneurysm treatment remains poorly characterized. This study aimed to evaluate the role of fibrin in early thrombus organization after flow diverter treatment. METHODS: Thirty-five elastase-induced aneurysms were induced in New Zealand white rabbits and subjected to endoluminal flow diversion treatment. The device-bearing arteries were harvested at 1, 3, and 6 months postimplantation and processed for histopathological examination, including a modified picro-Mallory stain (Carstairs method) to visualize fibrin and platelets, immunohistochemical targeting of smooth muscle actin (SMA), and H&E staining for conventional morphological evaluation. Quantitative analysis of tissue components was carried out using the Orbit Image Analysis software. The samples were also assessed qualitatively to investigate the morphology and location of fibrin and other thrombus components within the intra-aneurysmal thrombi. Statistical analyses were conducted using R software version 4.3.1. RESULTS: Fibrin constituted 27.9% of the thrombus tissue within the aneurysm sac for aneurysms harvested at 1 month, and this rate was significantly lower in the 3-month group (10.2%, p = 0.018). The proportion of blood cells within the sac was also notably higher in the 1-month group compared with other time points. The primary tissue filling the dome at 1 month (14/15, 93%) was an unorganized thrombus primarily composed of fibrin, platelets, and red blood cells. Conversely, aneurysms harvested at 1 month had the lowest collagen level (25.6%). However, collagen became the dominant tissue component within the aneurysm sac, accounting for 71.8% of tissue in the 3-month group (p = 0.007). There were no differences observed among the examined components between the 3-month and 6-month groups. On qualitative analysis, collagen-producing SMA-positive myofibroblasts were located near or in between fibrin molecules. Healed aneurysms exhibited myofibroblasts, collagen, and a well-organized fibrin network on the aneurysm neck. In contrast, unhealed aneurysms displayed a poorly organized fibrin network with scattered myofibroblasts at the neck area. CONCLUSIONS: These findings indicate that fibrin plays a foundational role in the gradual occlusion of aneurysms after flow diverter treatment. Endovascular approaches that enhance fibrin accumulation could potentially improve aneurysm occlusion rates. Further research is needed to establish the precise role of fibrin in aneurysm occlusion.

WEB shape modifications: angiography-histopathology correlations in rabbits.

BACKGROUND: WEB Shape Modification (WSM) over time is frequent after aneurysm treatment. In this study, we explored the relationship between histopathological changes and angiographic evolution over time in experimental aneurysms in rabbits treated with the Woven EndoBridge (WEB) procedure. METHODS: Quantitative WSM was assessed using flat-panel computed tomography (FPCT) during follow-up by calculating height and width ratio (HR, WR), defined as the ratio between either measurement at an index time point and the measurement immediately after WEB implantation. The index time point varied from 1 day to 6 months. HR and WR were evaluated with angiographic and histopathological assessments of aneurysm healing. RESULTS: Final HR of devices varied from 0.30 to 1.02 and final WR varied from 0.62 to 1.59. Altogether, at least 5% of HR and WR variations were observed in 37/40 (92.5%) and 28/40 (70%) WEB devices, respectively, at the time of final assessment. There was no significant correlation between complete or incomplete occlusion groups and HR or WR (p=0.15 and p=0.43). Histopathological analysis revealed a significant association between WR and aneurysm healing and fibrosis 1 month following aneurysm treatment (both p<0.05). CONCLUSION: Using longitudinal FPCT assessment, we observed that WSM affects both the height and width of the WEB device. No significant association was found between WSM and aneurysm occlusion status. Although presumably a multifactorial phenomenon, the histopathological analysis highlighted a significant association between width variations, aneurysm healing and fibrosis in the first month following aneurysm treatment.

Lack of aneurysm formation after carotid artery ligation in rabbits: a polymer MICROFIL® study.

INTRODUCTION: Previous studies have noted formation of saccular aneurysms along the distal basilar artery/P1 segments after carotid ligation in rabbits. In this prospective study we employed MICROFIL®, a polymer, which was used to fill the entire arterial tree, to examine the incidence of microaneurysm formation following right common carotid artery (RCCA) ligation in rabbits. METHODS: RCCA ligation was performed in 18 New Zealand White rabbits for 0 day (n = 2), 3 weeks (n = 6), or 16 weeks (n = 10). Three control rabbits without carotid surgery were sacrificed at 4 weeks. At the time of sacrifice, MICROFIL® MV-122 yellow was injected through left CCA to fill cerebral vasculature. After gross photographs were taken, specimens were embedded, sectioned, and stained for histopathological evaluation. Tissue and sections were carefully evaluated for microaneurysm formation, defined as a localized dilatation of the vessel wall, associated with fragmentation or complete loss of the internal elastic lamina (IEL), and/or medial degeneration. RESULTS: Gross examination with MICROFIL® opacification demonstrated no evidence of saccular aneurysm formation, but prominent perforating vessels were present in all 19 cases at, or adjacent to, the basilar terminus. Branches noted upon gross examination corresponded histologically to small, saccular contour defects, which demonstrated apparent loss of the IEL and apparent medial thinning. These observations, however, were a consequence of sectioning through the bases of perforating arteries, which simulated microaneurysm formation. CONCLUSIONS: Unilateral carotid ligation does not induce microaneurysm formation at the basilar terminus in rabbits. Prominent perforating arteries as well as tissue injury from the processing may simulate "aneurysms" histologically.

Quality assessment of histopathological stainings on prolonged formalin fixed thrombus tissues retrieved by mechanical thrombectomy.

Background: Formalin-fixed retrieved clots from mechanical thrombectomy (MT) are now routinely studied using both conventional histopathologic techniques and immunohistochemistry (IHC). However, the effects of prolonged formalin fixation on the histological results of clot analysis remain unknown. The objective of this study was to investigate the effects of prolonged formalin fixation on quality of histopathologic stainings of thrombus tissues retrieved by MT. Methods: As part of the multicenter EXCELLENT registry, a total of 80 clots extracted by MT from acute ischemic stroke patients were randomly selected from the tissue database and assigned into four groups according to 10% neutral buffered formalin (NBF) fixation duration (1-30, 30-60, 60-90, and 90+ days, up to 2 years). Samples underwent processing and sectioning. Two serial sections for each case were stained with hematoxylin and eosin (H&E), Martius Scarlet Blue (MSB), and IHC for CD42b (platelet marker). An expert pathologist, who was blinded to tissue fixation duration and patient clinical data, assessed the quality of each stain including stainability, sensitivity, specificity, and consistency of stainings. Results: No significant issues were encountered during tissue processing and sectioning. On H&E stain, 97.5% (78/80) of slides showed good-quality staining, demonstrating clear histological properties of the thrombus tissue as red blood cells (RBC) stained in red, fibrin/platelet stained in pink, and nuclei stained in blue with intranuclear detail. The same histological features were also successfully demonstrated on MSB for all 80 samples. One of the 80 samples (1.2%) showed that RBC lost stainability on H&E due to tissue autolysis. Clear positive signal of platelet staining was expressed in 98.8% of the samples (79/80) with minimal background staining on IHC. There was no significant difference in staining quality across different formalin fixation groups. Conclusion: A good quality of histopathological staining is achievable for the thrombus tissue fixed in 10% neutral buffered formalin for up to 2 years. The findings are limited to the thrombus tissue retrieved by MT and specific fixation and staining protocols used in the study. To apply these results to other tissue or experimental setups, further studies and validations would be necessary. Clinical trial registration: This study was conducted as part of the EXCELLENT study: www.clinicaltrials.gov, unique identifier: NCT03685578.

An in vitro model for Extracellular DNA Traps (ETs)-rich Human Thrombus Analogs.

BACKGROUND: Extracellular DNA traps (ETs) have important implications in both thrombosis and thrombolysis. Thus, developing benchtop thrombus analogs that recapitulate clinical ETs is potentially of great value for preclinical development and testing of thrombolytic agents and thrombectomy devices. In this study, we aimed to develop ETs-rich thrombus analogs for preclinical testing. METHODS: Red blood cell (RBC)-rich, fibrin-rich, and platelet-rich thrombus analogs were created using human whole blood, platelet-poor plasma, and platelet-rich plasma obtained from the blood bank following institutional approval. Peripheral blood mononuclear cells (9.9×106 cells/mL) isolated from human whole blood and lipopolysaccharide (1 µg/mL) were added to induce ETs. Histochemical, immunohistochemistry and immunofluorescence were used to identify thrombus components and ETs. Scanning electronic microscopy was used to investigate the ultrastructure of the thrombus analogs. The thrombus compositions, morphologic features of ETs and citrullinated histone H3 (H3Cit) expression were compared with those of thrombi retrieved from patients by thrombectomy. RESULTS: ETs-rich thrombus analogs were more compacted th-an the ETs-poor thrombus analogs. ETs were identified in both ETs-rich thrombus analogs and patient thrombi showing morphologic features including nuclear lobulation, nuclear swelling, diffused chromatin within cytoplasm, DNA/chromatin extending intracellularly and extracellularly, and extracellular chromatin patches and bundles. In the ETs-poor thrombus analogs, ETs were not observed and H3Cit expression was absent to minimal. The compositions and H3Cit expression in the ETs-rich thrombus analogs fell in the range of patient thrombi. CONCLUSIONS: ETs-rich thrombus analogs can be consistently created in vitro and may benefit the preclinical development and testing of new thrombolytic agents and thrombectomy devices.

Shell Versus Core Architecture and Biology of Thrombi in Acute Ischemic Stroke: A Systematic Review.

BACKGROUND: The presence of an outer shell has been recently described as a common feature of acute ischemic stroke (AIS) thrombi. We performed a systematic review of the current literature on shell genesis, structure, and clinical significance. METHODS: Following PRISMA guidelines, we searched Ovid Cochrane Central Register of Controlled Trials, Embase, Medline, Scopus, and Web of Science for studies reporting the composition and structure of AIS thrombi and clot analogs. Identified studies were added to Covidence software for primary screening. Two reviewers independently screened titles and abstracts followed by full-text screening. RESULTS: From 1290 identified studies, 10 were included in this review. Studies using histology/immunohistochemistry/immunofluorescence described fibrin, platelets, von Willebrand factor, and neutrophil extracellular traps as the main components of the shell. Scanning electron microscopy demonstrated a dense, compact fibrin/platelet-rich shell, and a core rich in polyhedrocytes. Microfluidics studies identified highly activated P-selectin-positive platelets and fibrin forming the core while secondary agonists adenosine diphosphate and thromboxane, along with loosely packed P-selectin-negative platelets constituted the shell. CONCLUSIONS: The composition, compaction, and integrity of the shell may impact thrombolysis and revascularization outcomes. The preponderance of studies supported this conclusion.

Correlation of von Willebrand factor and platelets with acute ischemic stroke etiology and revascularization outcome: an immunohistochemical study.

BACKGROUND: Platelets and von Willebrand factor (vWF) are key components of acute ischemic stroke (AIS) emboli. We aimed to investigate the CD42b (platelets)/vWF expression, its association with stroke etiology and the impact these components may have on the clinical/procedural parameters. METHODS: CD42b/vWF immunostaining was performed on 288 emboli collected as part of the multicenter STRIP Registry. CD42b/VWF expression and distribution were evaluated. Student's t-test and χ2 test were performed as appropriate. RESULTS: The mean CD42b and VWF content in clots was 44.3% and 21.9%, respectively. There was a positive correlation between platelets and vWF (r=0.64, p<0.001**). We found a significantly higher vWF level in the other determined etiology (p=0.016*) and cryptogenic (p=0.049*) groups compared with cardioembolic etiology. No significant difference in CD42b content was found across the etiology subtypes. CD42b/vWF patterns were significantly associated with stroke etiology (p=0.006*). The peripheral pattern was predominant in atherosclerotic clots (36.4%) while the clustering (patchy) pattern was significantly associated with cardioembolic and cryptogenic origin (66.7% and 49.8%, respectively). The clots corresponding to other determined etiology showed mainly a diffuse pattern (28.1%). Two types of platelets were distinguished within the CD42b-positive clusters in all emboli: vWF-positive platelets were observed at the center, surrounded by vWF-negative platelets. Thrombolysis correlated with a high platelet content (p=0.03*). vWF-poor and peripheral CD42b/vWF pattern correlated with first pass effect (p=0.03* and p=0.04*, respectively). CONCLUSIONS: The vWF level and CD42b/vWF distribution pattern in emboli were correlated with AIS etiology and revascularization outcome. Platelet content was associated with response to thrombolysis.

L-Arginine reduces downstream vascular contractility after flow-diverting device deployment: A preliminary study in a rabbit model.

BACKGROUND: Flow diverters (FDs) are an effective treatment for intracranial aneurysms, though not free from hemorrhagic complications. A previous study demonstrated increased vascular contractility after FD-implantation as a potential mechanism of distal complications. Our study aimed to investigate whether L-arginine medication affects vascular contractility following FD deployment in a rabbit model. METHODS: FDs were implanted in the aorta of normal rabbits (+FD, n = 10), with sham-operated aorta as controls (n = 5). L-Arginine was given in the drinking water (2.25% L-arginine hydrochloride) of half of the +FD animals (+FD/+Arg). Force contraction vascular contractility studies were performed on the aortic rings proximal and distal to the FD using an organ bath. Total eNOS, eNOS(pS1177), eNOS(pT495), COX-2, and S100A4 were quantified by western analysis on total protein lysates from aortic segments, normalizing to GAPDH. RESULTS: Mean vascular contractility was 53% higher in distal relative to proximal aortic segments (P = 0.0038) in +FD animals, but were not significantly different in +FD/+Arg animals, or in sham-operated controls. The +FD animals expressed significantly reduced levels of eNOS(pS1177) than sham-operated controls (P = 0.0335), while both the +FD and +FD/+Arg groups had reduced levels of eNOS(pT495) relative to sham-operated controls (P = 0.0331 and P = 0.0311, respectively). CONCLUSION: These results suggest that L-arginine medication reduces distal vascular contractility after FD treatment via nitric oxide production and thus might mitigate risk for downstream complications.

Diverse thrombus composition in thrombectomy stroke patients with longer time to recanalization.

BACKGROUND AND PURPOSE: Delayed time to recanalization is associated with reduced recanalization success of mechanical thrombectomy (MT) and thrombolysis in acute ischemic stroke (AIS). The reasons for this are unclear. We hypothesized that alterations in thrombus structure and composition could be responsible for this. METHODS: Retrieved thrombi from AIS patients who underwent MT less than 8 h from symptom onset to groin puncture (SOGP) were evaluated. Patients were divided into early (≤4 h.) vs delayed (> 4 h) groups based SOGP timing. Thrombi were histologically analysed using Martius Scarlett Blue and immunohistochemistry staining for von Willebrand Factor (vWF), anti-citrullinated H3 (H3Cit; NETs [neutrophil extracellular traps] marker). We used inferential statistics including, t-test, artificial neural network (ANN) to interpret the data. RESULTS: A total of 137 thrombi were collected. The overall average percentage of red blood cells (RBC), white blood cells (WBC), platelet, fibrin, H3Cit, and vWF components in thrombi was 45.83%, 3.58%, 22.23%, 28.27%, 19.97% and 16.23% respectively. Delayed group had higher WBCs, (p = 0.02), fibrin (p = 0.02), H3Cit (p = 0.04) and vWF (p = 0.03) thrombus fractions compared to early group. Based on ANN model, the most important factors for predicting the number of passes required for successful recanalization are fibrin and RBC contents of the thrombus followed by vWF and H3Cit contents. CONCLUSIONS: Longer time to recanalization was associated with increased WBCs, fibrin, H3Cit and vWF fractions of thrombi reflecting possible in situ maturation of thrombus components. Increased fibrin, NETs and vWF composition may reduce likelihood of revascularization by altering thrombus mechanical properties.

Novel Focal Therapeutic Hypothermia Device for Treatment of Acute Neurologic Injury: Large Animal Safety and Efficacy Trial.

Objective Therapeutic hypothermia is a potentially powerful and controversial clinical tool for neuroprotection following acute neurologic pathology, particularly vascular injury. Indeed, therapeutic hypothermia remains a standard of care for postcardiac arrest ischemia and acute neonatal hypoxic-ischemic encephalopathy, improving both survival and outcomes. Although therapeutic hypothermia remains promising for cellular and systems-based neuronal protection in other neurologic injury states, the systemic side effects have limited clinical utility, confounded analysis of potential neurologic benefits, and precluded the completion of meaningful clinical trials. Methods To address such limitations, we developed and tested a novel, minimally invasive, neurocritical care device that employs continuous circulation of cold saline through the pharyngeal region to deliver focal cerebrovascular cooling. We conducted a preclinical safety and efficacy trial in six adult porcine animals to assess the validity and functionality of the NeuroSave device, and assess cooling potential following middle cerebral artery occlusion ( n = 2). Results NeuroSave consistently lowered brain parenchymal temperature by a median of 9°C relative to core temperature within 60 minutes of initiation, including in ischemic cerebral parenchyma. The core body temperature experienced a maximal reduction of 2°C, or 5% of body temperature, with no associated adverse effects identified. Conclusion The present study uses a large animal preclinical model to demonstrate the safety and efficacy of a novel, noninvasive device for the induction of robust and systemically safe hypothermia within the brain.

Correlation of Neutrophil to Lymphocyte Ratio with Expression of Neutrophil Extracellular Traps Within Stroke Emboli.

BACKGROUND & PURPOSE: It has been hypothesized that circulating neutrophils have a direct correlation with the composition of emboli in acute ischemic stroke (AIS). The aim of this study is to evaluate the association between neutrophil-lymphocyte ratio (NLR) in peripheral blood and the expression of neutrophil extracellular traps (NETs) within stroke emboli. METHODS: Consecutive patients with acute ischemic stroke (AIS) due to large vessel occlusion (LVO) that underwent mechanical thrombectomy (MT) were included. Patients were divided into two groups based on NLR median value. Retrieved thrombi were histologically analyzed using Martius Scarlett Blue (MSB) for main thrombus components including red blood cells (RBCs), white blood cells (WBCs), fibrin and platelet. Immunohistochemistry staining for von Willebrand Factor (vWF) and anti-citrullinated H3 (H3Cit; NETs marker) was also performed. RESULTS: Samples from a total of 84 patients were included. The average percentage of RBCs, WBCs, fibrin, platelet, H3Cit, and vWF components in thrombi were 45.1%, 3.5%, 21.8%, 29.6%, 19.7% and 14.8% respectively. When stratifying by NLR group [low (≤3.94) versus high (>3.95)], high NLR group had significantly more WBCs (4.5%), fibrin (24.2%), H3Cit (22.7%) and vWF (17.1%) thrombus fractions compared to low NLR group. Additionally, RBC content (38.8%) was lower in the high NLR group. CONCLUSIONS: NLR is correlated with the amounts of WBCs, fibrin, NETs and vWF within the thrombi retrieved from AIS patients due to LVO.

Histological evaluation of acute ischemic stroke thrombi may indicate the occurrence of vessel wall injury during mechanical thrombectomy.

BACKGROUND: Several animal studies have demonstrated that mechanical thrombectomy (MT) for acute ischemic stroke (AIS) may cause vessel wall injury (VWI). However, the histological changes in human cerebral arteries following MT are difficult to determine. OBJECTIVE: To investigate the occurrence of VWI during MT by histological and immunohistochemical evaluation of AIS clots. METHODS: As part of the multicenter STRIP registry, 277 clots from 237 patients were analyzed using Martius Scarlett Blue stain and immunohistochemistry for CD34 (endothelial cells) and smooth muscle actin (smooth muscle cells). RESULTS: MT devices used were aspiration catheters (100 cases), stentriever (101 cases), and both (36 cases). VWI was found in 33/277 clots (12%). There was no significant correlation between VWI and MT device. The degree of damage varied from grade I (mild intimal damage, 24 clots), to grade II (relevant intimal and subintimal damage, 3 clots), and III (severe injury, 6 clots). VWI clots contained significantly more erythrocytes (p=0.006*) and less platelets/other (p=0.005*) than non-VWI clots suggesting soft thrombus material.Thrombolysis correlated with a lower rate of VWI (p=0.04*). VWI cases showed a significantly higher number of passes (2 [1-4] vs 1 [1-3], p=0.028*) and poorer recanalization outcome (p=0.01*) than cases without VWI. CONCLUSIONS: Histological markers of VWI were present in 12% of AIS thrombi, suggesting that VWI might be related to MT. VWI was associated with soft thrombus consistency, higher number of passes and poorer revascularization outcome. There was no significant correlation between VWI and MT device.

Quantification of clot spatial heterogeneity and its impact on thrombectomy.

BACKGROUND: Compositional and structural features of retrieved clots by thrombectomy can provide insight into improving the endovascular treatment of ischemic stroke. Currently, histological analysis is limited to quantification of compositions and qualitative description of the clot structure. We hypothesized that heterogeneous clots would be prone to poorer recanalization rates and performed a quantitative analysis to test this hypothesis. METHODS: We collected and did histology on clots retrieved by mechanical thrombectomy from 157 stroke cases (107 achieved first-pass effect (FPE) and 50 did not). Using an in-house algorithm, the scanned images were divided into grids (with sizes of 0.2, 0.3, 0.4, 0.5, and 0.6 mm) and the extent of non-uniformity of RBC distribution was computed using the proposed spatial heterogeneity index (SHI). Finally, we validated the clinical significance of clot heterogeneity using the Mann-Whitney test and an artificial neural network (ANN) model. RESULTS: For cases with FPE, SHI values were smaller (0.033 vs 0.039 for grid size of 0.4 mm, P=0.028) compared with those without. In comparison, the clot composition was not statistically different between those two groups. From the ANN model, clot heterogeneity was the most important factor, followed by fibrin content, thrombectomy techniques, red blood cell content, clot area, platelet content, etiology, and admission of intravenous tissue plasminogen activator (IV-tPA). No statistical difference of clot heterogeneity was found for different etiologies, thrombectomy techniques, and IV-tPA administration. CONCLUSIONS: Clot heterogeneity can affect the clot response to thrombectomy devices and is associated with lower FPE. SHI can be a useful metric to quantify clot heterogeneity.

Gene expression changes: five years after creation of elastase-induced aneurysms.

PURPOSE: Intracranial saccular aneurysms are associated with chronic remodeling of the arterial wall. The pathobiology of aneurysm growth and rupture is poorly understood. The present study was performed to study the gene expression patterns in elastase-induced saccular aneurysms in rabbits 5 years after aneurysm creation, compared with unoperated control arteries. MATERIALS AND METHODS: Elastase-induced saccular aneurysms were created in 25 rabbits and followed up for 5 years. Thirteen rabbits died during follow-up for reasons unrelated to the aneurysms. RNA was isolated from aneurysm tissue and the control contralateral common carotid artery in five of the 12 surviving animals, and analyzed for gene expression by using human gene microarrays. Genes with statistical differences between groups (P < .05 and fold change ≥ 1.5 and ≤ 0.75) were considered differentially expressed. Real-time polymerase chain reaction (RT-PCR) was used for confirmation of gene microarray findings for selected genes. RESULTS: Fifty-three of 13,353 genes (0.4%) were differentially expressed in the aneurysms compared with the unoperated control arteries. Molecular and functional pathway analysis revealed that immunoregulatory molecules, growth factors, cell adhesion molecules, and structural molecules were differentially expressed in the aneurysms compared with controls. RT-PCR results of selected genes confirmed the differential expression identified by using the gene chip microarray. CONCLUSIONS: Significant modulation in a variety of biochemical and cellular functions in chronic aneurysms provides molecular insights into the pathophysiology of saccular aneurysms.