Focal Ischemia Research Articles

MicroRNA miR-7 Is Essential for Post-stroke Functional Recovery.

Transient focal ischemia induces a sustained downregulation of miR-7 leading to derepression of its target α-synuclein (α-Syn), which promotes neuronal death. We previously showed that treatment with miR-7 mimic prevents α-Syn induction and protects brain after stroke in rodents irrespective of age and sex. To further decipher the role of miR-7, we currently studied infarction and motor function in miR-7 double knockout mice (lack both miR-7a and miR-7b) subjected to focal ischemia. Adult miR-7-/- mice showed similar motor and cognitive functions to miR-7+/+ mice. However, when subjected to even a mild focal ischemia, the miR-7-/- mice showed exacerbated brain damage and worsened motor function compared with the miR-7+/+ mice. Replenishing miR-7 in miR-7-/- mice (IV injection of miR-7 mimic) restored miR-7 mediated neuroprotection and motor recovery, potentially by preventing α-Syn protein induction. Thus, we show that miR-7 is an essential miRNA in the brain that prevents α-Syn translation and the ensuing brain damage after stroke.

Мігрень: деякі вікові, гендерні та патогенетичні аспекти, проблема коморбідності (огляд літератури та клінічне спостереження

У статті наводяться літературні дані про поширеність мігрені. Показано, що для пацієнтів із мігренню характерна варіабельність частоти, тривалості та інтенсивності мігренозних нападів, спектра провідних клінічних проявів, а також наявність специфічних для кожного пацієнта провокуючих чинників. Подані сучасні дані по деяких патогенетичних аспектах мігрені, звернуто увагу на суворі кореляційні зв’язки частоти головного болю з гормональними змінами, віком пацієнтів. Підкреслено, що гендерні відмінності, гормональні порушення є важливими факторами ініціації нападів мігрені. Наведено дані численних клінічних і експериментальних досліджень, які показують, що високий рівень естрогенів корелює з більш високою больовою толерантністю. Звернуто увагу на проблему коморбідності мігрені з іншими захворюваннями. Наводиться власне клінічне спостереження мігрені, ускладненої інфарктом головного мозку з нетиповою локалізацією ішемічного вогнища.

Особливості біохіміко-метаболічних показників у хворих на первиний гострий ішемічний інсульт на тлі метаболічного синдрому та без такого

Актуальність. Проведено оцінку залежності ступеня неврологічного дефіциту в пацієнтів із гострим ішемічним інсультом від біохімічних та метаболічних показників метаболічного синдрому. Мета дослідження — визначення біохіміко-метаболічних показників у хворих на первинний гострий ішемічний інсульт із метаболічним синдромом та без такого. Матеріали та методи. Матеріал: 160 пацієнтів із гострим первинним ішемічним інсультом (чоловіків — 103, жінок — 57) віком від 39 до 91 року. Методи: артеріальна тонометрія, пульсометрія, електрокардіографія, антропометрія, глюкометрія, ліпідометрія, транскраніальна допплерографія, магнітно-резонансна томографія, неврологічні. Результати. Установлено, що біохіміко-метаболічні порушення, які лежать в основі виникнення метаболічного синдрому в рамках гострої церебральної катастрофи, впливають на формування вогнища ішемії, збільшуючи його, що викликає поглиблення неврологічного дефіциту. Класифікацію патогенетичних підтипів інсульту здійснювали за Adams (1993). Виявлено вплив атерогенної дисліпідемії на виникнення атеротромботичного та лакунарного підтипів інсульту як основи патобіохімічної ланки формування цих підтипів. До того ж атеротромботичний потенціал у пацієнтів із метаболічним синдромом був високим. Вірогідне превалювання обсягу неврологічного дефіциту та середнього розміру вогнища ішемії при атеротромботичному та кардіоемболічному підтипах інсульту свідчить про негативний вплив метаболічних і біохімічних порушень на перебіг ішемічного інсульту. Висновок. Доведено, що гіперглікемія як основа біохімічних та метаболічних процесів в організмі не тільки є незалежним предиктором виникнення ішемічного інсульту, але й у поєднанні з іншими факторами метаболічного синдрому впливає на формування розмірів вогнища ішемії, вираженість неврологічного дефіциту та його еволюцію.

Lithium Chloride Effect on Mortality and Neurological Deficits in the Model of Ischemic Stroke in Rats

The relevance of the problem of ischemic stroke is difficult to overvalue in modern terms. The data on the frequency of occurrence and outcomes, especially among young people, force us to look for new strategies to minimize its consequences. Recent experimental studies have shown pronounced neurocardio-nephroprotective properties of lithium salts.Aim of study. To evaluate the effect of lithium chloride on the lethality and severity of cognitive and neurological deficits in the modeling of ischemic stroke in rats.Materials and methods. The study used mongrel male rats weighing 312±12.5 g. The model of Longa’s focal ischemia was used as a basis. The animals were divided into 5 groups: false-operated, control (model of ischemic stroke with the introduction of 0.9% NaCl) and three groups with the introduction of lithium chloride in various concentrations (4.2 mg/kg, 21 mg/kg and 63 mg/kg). The drug was administered daily for 14 days with a parallel assessment of neurological deficits.Results. According to the results of the experiment, the following data were obtained with respect to lethality in the studied groups: false — operated 0 out of 8, control group — 13 out of 22 (lethality 59%), group 3 (LiCl 4.2 mg/kg) — 8 out of 14 (lethality 57%), p>0.05 with respect to control, group 4 (LiCl 21 mg/kg) — 6 out of 15 (lethality 40%) p>0.05 with respect to control and in group 5 (LiCl 63 mg/kg) — 4 out of 15 animals died (lethality 27%) p=0.0317. Lithium chloride at doses of 21 mg/kg and 63 mg/kg resulted in a decrease in the severity of neurological deficits on the second day of the experiment. On the 15th day of the experiment, there were no differences in the severity of neurological disorders. Also, the dosage of 63 mg/kg contributed to better memory retention during the assessment of cognitive functions.Conclusion. Lithium chloride at a dosage of 63 mg/kg significantly (p=0.037) reduced the mortality and severity of neurological deficits in the simulation of experimental ischemic stroke in rats compared to the control group.

Postmortem brain 7T MRI with minimally invasive pathological correlation in deceased COVID-19 subjects

BackgroundBrain abnormalities are a concern in COVID-19, so we used minimally invasive autopsy (MIA) to investigate it, consisting of brain 7T MR and CT images and tissue sampling via transethmoidal route with at least three fragments: the first one for reverse transcription polymerase chain reaction (RT-PCR) analysis and the remaining fixed and stained with hematoxylin and eosin. Two mouse monoclonal anti-coronavirus (SARS-CoV-2) antibodies were employed in immunohistochemical (IHC) reactions.ResultsSeven deceased COVID-19 patients underwent MIA with brain MR and CT images, six of them with tissue sampling. Imaging findings included infarcts, punctate brain hemorrhagic foci, subarachnoid hemorrhage and signal abnormalities in the splenium, basal ganglia, white matter, hippocampi and posterior cortico-subcortical. Punctate brain hemorrhage was the most common finding (three out of seven cases). Brain histological analysis revealed reactive gliosis, congestion, cortical neuron eosinophilic degeneration and axonal disruption in all six cases. Other findings included edema (5 cases), discrete perivascular hemorrhages (5), cerebral small vessel disease (3), perivascular hemosiderin deposits (3), Alzheimer type II glia (3), abundant corpora amylacea (3), ischemic foci (1), periventricular encephalitis foci (1), periventricular vascular ectasia (1) and fibrin thrombi (1). SARS-CoV-2 RNA was detected with RT-PCR in 5 out of 5 and IHC in 6 out 6 patients (100%).ConclusionsDespite limited sampling, MIA was an effective tool to evaluate underlying pathological brain changes in deceased COVID-19 patients. Imaging findings were varied, and pathological features corroborated signs of hypoxia, alterations related to systemic critically ill and SARS-CoV-2 brain invasion.

Association between blood coagulability and migraine

BackgroundAn association between migraine and stroke has been suggested for a long period, although conclusive evidence has not been reported. Several theories about hypercoagulability have been proposed for the association of ischemic stroke and migraine especially migraine with aura. This study aimed to assess blood coagulability in patients with migraine.ResultsMean serum levels of protein S and anti-thrombin III were significantly lower in migraine patients compared to control subjects. Migraine patients showed abnormal MRI findings in the form of white matter hyper-intense lesions and ischemic foci compared to healthy controls. A significant negative correlation was detected between serum protein C level and intensity of migraine headache. Also, a significant correlation was found between deficient serum protein S and abnormal findings in brain MRI. Serum protein C deficiency is an independent predictor for migraine intensity grade.ConclusionsThere is an association between migraine and hypercoagulability, which may indicate increased risk of cerebral ischemic events in migraine patients and suggest adding prophylactic therapy to the management strategies of such patients.

Alleviative effects of foraging exercise on depressive-like behaviors in chronic mild stress-induced ischemic rat model

ABSTRACT Background Poststroke depression (PSD) is a common complication that seriously affects the functional recovery and prognosis of an individual. As some patients with PSD fail to respond to drug therapy, it is urgent to find a viable alternative treatment. Methods An active exercise program known as foraging exercise (FE), using food as bait, was designed. First, focal ischemia and chronic unpredictable mild stress (CUMS) were used to establish a PSD model in rats. FE was then performed for 4 weeks. Body weight and behavioral assessments were conducted at the end of the 4th and 8th weeks. Results After 8 weeks, the results revealed that, compared with the PSD group, the behavioral scores of the rats in the PSD/FE group were significantly improved, the expression of Iba-1 in the affected frontal lobe and striatum was decreased, and serum levels of IL-6 and the IL-6/IL-10 ratio were downregulated. However, the ratio of residual brain volume in rats that had experienced CUMS was significantly less than that in the stroke group. Conclusion FE can alleviate the behavioral scores of PSD rats, and its mechanism may be related to a modulation of the immune-inflammation response of microglia. Furthermore, chronic, persistent stress may increase the volume of cerebral infarction after stroke.

Results of carotid endarterectomy in the acutest period of ischemic stroke

Analysis of the results of carotid endarterectomy (CEE) in the acute period of ischemic stroke (IS). This retrospective study included 128 patients (mean age 65.2±4.7 years, 84 (65.6%) men) who underwent CEE in the acute period. Inclusion criteria were: an ischemic focus in the brain with a diameter of no more than 2.5 cm according to MRI; mild neurological deficit (from 3 to 8 points on NIHSS); ≤3 points on the modified Rankin Scale (mRS); stenosis of ICA over 60%. Exclusion criteria were: severe neurological deficit; presence of decompensated comorbid dependence; contraindications to CEE. In the hospital postoperative period, 3.9% of patients were diagnosed with hemorrhagic transformation of the ischemic focus in the brain with progression of neurological deficit and level of consciousness to coma II. In 3.1% cases, a lethal outcome developed on 4-7 days after the operation. In 2.3% patients after CEE, the progression of neurological deficit was noted with the development of new ischemic foci according to postoperative neuroimaging. The probable cause of this event was a distal embolism that developed during the installation of a temporary shunt. Myocardial infarction was diagnosed in 3.9% of patients. The combined end point (death + myocardial infarction + ischemic stroke + hemorrhagic transformation) was 10.1%. CEE in the most acute period of ischemic stroke is accompanied by a high risk of hemorrhagic transformation, myocardial infarction, and death, which characterizes this revascularization option as unsafe.

Connexin 43 Mediated the Angiogenesis of Buyang Huanwu Decoction via Vascular Endothelial Growth Factor and Angiopoietin-1 after Ischemic Stroke

Buyang Huanwu decoction (BYHWD), a classical prescription for ischemic stroke, has been reported to promote angiogenesis after focal ischemia. However, the mechanisms of the contribution of BYHWD on angiogenesis are still unclear. Connexin 43 (Cx43) played important roles in the functions of neurogliovascular unit. Therefore, the aim of this study was to explore the potential role of Cx43 in angiogenesis of the ischemic brain after BYHWD treatment. Middle cerebral artery occlusion (MCAO) was used to establish the model of focal ischemia. BYHWD was administrated intragastrically twice a day after MCAO with or without Gap26 (a specific Cx43 inhibitor). Western blot, neurological deficits, immunofluorescent staining, and Evans blue dye were used to confirm the role of Cx43 in angiogenesis after BYHWD treatment. The expression levels of total Cx43 and phosphorylated Cx43 were upregulated by BYHWD and peaked at 7 days post MCAO. Inhibition of Cx43 with Gap26 significantly attenuated the protective role of BYHWD in neurological behavior. BYHWD treatment promoted angiogenesis demonstrated by increased microvascular density, upregulated vascular endothelial growth factor (VEGF), and angiopoietin-1 (Ang-1), while inhibition of Cx43 with Gap26 attenuated these effects of BYHWD. In addition, Gap26 inhibited the beneficial effect of BYHWD on blood-brain barrier (BBB) integrity. These results suggested that Cx43 mediated the angiogenesis of BYHWD via VEGF and Ang-1 after focal ischemic stroke.

Critical role of FPR1 in splenocyte migration into brain to worsen inflammation and ischemic brain injury in mice.

Background: Splenocyte contribution to ischemic brain injury has been suggested. It is not known whether this effect is due to systemic action or direct influence in ischemic brain tissues. It is also not known how splenocytes migrate into the brain and worsen neurological outcome after brain ischemia. We determined the role of formyl peptide receptor 1 (FPR1), a receptor expressed in monocytes, in the migration of splenocytes into ischemic brain tissues and the contribution of these splenocytes to ischemic brain injury.Methods: Mice with or without fpr1 knockout were subjected to transient focal brain ischemia. The migration of splenocytes was assessed under in vivo and in vitro conditions.Results: cFLFLF, a FPR1 antagonist, inhibited splenocyte migration into the brain and neuroinflammation after ischemic stroke. cFLFLF improved neurological outcome assessed 24 hours or 28 days after stroke. cFLFLF did not alter blood-brain barrier permeability in the ischemic brain. fpr1-/- mice had an attenuated peripheral monocyte and neutrophil infiltration into the brain, a reduced proinflammatory cytokine level and an improved neurological outcome compared with wild-type mice after brain ischemia. cFLFLF did not affect the proinflammatory cytokine levels in the spleen and brain of fpr1-/- mice after ischemic stroke.Conclusions: These results suggest that FPR1 facilitates splenocyte migration into the brain and proinflammatory cytokine production to worsen neurological outcome after brain ischemia, indicating a direct effect of splenocytes on ischemic brain tissues. Our results support the notion that cFLFLF via blocking FPR1 signaling inhibits those pathological processes and is a potential agent for neuroprotection.

Sustained delivery of focal ischemia coupled to real-time neurochemical sensing in brain slices.

Local stimulation of tissue can occur naturally in events like immune-mediated inflammation and focal ischemic injuries in brain and is confined to specific regions within tissue, occurring on various timescales. Making chemical measurements at the exact site of stimulation with current technologies is difficult yet important for understanding tissue response. We have developed a microfluidic device capable of local stimulation of brain slices with minimal lateral spread over time and submillimeter, tunable spatial resolution. This device is compatible with electrochemical measurements to monitor signaling at the site of stimulation over time. The PDMS-based device is three layers and contains a culture well, channel layer, and exit port layer for the channels. Channels with exit ports straddling the stimulus channels and ports were specifically fabricated to focus the stimulus over time. We demonstrated that the device is compatible with fast-scan cyclic voltammetry (FSCV) recording of neurotransmitter release. Localized hypoxia in tissue was verified using Image-iT Green Hypoxia Reagent and coupling this device with FSCV enabled measurement of local dopamine changes at the site of focal ischemia for the first time. This work provides a significant advance in knowledge of local neurochemical fluctuations during sustained tissue injury. Overall, the unique capabilities of the device to deliver sustained localized stimulation combined with real-time sensing provide an innovative platform to answer significant biological questions about how tissues respond at the site of controlled, localized injury and chemical stimulation.

Inhibition of the renin-angiotensin system causes concentric hypertrophy of renal arterioles in mice and humans.

Inhibitors of the renin-angiotensin system (RAS) are widely used to treat hypertension. Using mice harboring fluorescent cell lineage tracers, single-cell RNA-Seq, and long-term inhibition of RAS in both mice and humans, we found that deletion of renin or inhibition of the RAS leads to concentric thickening of the intrarenal arteries and arterioles. This severe disease was caused by the multiclonal expansion and transformation of renin cells from a classical endocrine phenotype to a matrix-secretory phenotype: the cells surrounded the vessel walls and induced the accumulation of adjacent smooth muscle cells and extracellular matrix, resulting in blood flow obstruction, focal ischemia, and fibrosis. Ablation of the renin cells via conditional deletion of β1 integrin prevented arteriolar hypertrophy, indicating that renin cells are responsible for vascular disease. Given these findings, prospective morphological studies in humans are necessary to determine the extent of renal vascular damage caused by the widespread use of inhibitors of the RAS.

Effect of Neurorepair for Motor Functional Recovery Enhanced by Total Saponins From Trillium tschonoskii Maxim. Treatment in a Rat Model of Focal Ischemia.

Trillium tschonoskii Maxim. (TTM), is a perennial herb from Liliaceae, that has been widely used as a traditional Chinese medicine treating cephalgia and traumatic hemorrhage. The present work was designed to investigate whether the total saponins from Trillium tschonoskii Maxim. (TSTT) would promote brain remodeling and improve gait impairment in the chronic phase of ischemic stroke. A focal ischemic model of male Sprague-Dawley (SD) rats was established by permanent middle cerebral artery occlusion (MCAO). Six hours later, rats were intragastrically treated with TSTT (120, 60, and 30 mg/kg) and once daily up to day 30. The gait changes were assessed by the CatWalk-automated gait analysis system. The brain tissues injuries, cerebral perfusion and changes of axonal microstructures were detected by multimodal magnetic resonance imaging (MRI), followed by histological examinations. The axonal regeneration related signaling pathways including phosphatidylinositol 3-kinases (PI3K)/protein kinase B (AKT)/glycogen synthase kinase-3 (GSK-3)/collapsin response mediator protein-2 (CRMP-2) were measured by western blotting. TSTT treatment significantly improved gait impairment of rats. MRI analysis revealed that TSTT alleviated tissues injuries, significantly improved cerebral blood flow (CBF), enhanced microstructural integrity of axon and myelin sheath in the ipsilesional sensorimotor cortex and internal capsule. In parallel to MRI findings, TSTT preserved myelinated axons and promoted oligodendrogenesis. Specifically, TSTT interventions markedly up-regulated expression of phosphorylated GSK-3, accompanied by increased expression of phosphorylated PI3K, AKT, but reduced phosphorylated CRMP-2 expression. Taken together, our results suggested that TSTT facilitated brain remodeling. This correlated with improving CBF, encouraging reorganization of axonal microstructure, promoting oligodendrogenesis and activating PI3K/AKT/GSK-3/CRMP-2 signaling, thereby improving poststroke gait impairments.

Identifying the Involvement of Pro-Inflammatory Signal in Hippocampal Gene Expression Changes after Experimental Ischemia: Transcriptome-Wide Analysis.

Acute cerebral ischemia induces distant inflammation in the hippocampus; however, molecular mechanisms of this phenomenon remain obscure. Here, hippocampal gene expression profiles were compared in two experimental paradigms in rats: middle cerebral artery occlusion (MCAO) and intracerebral administration of lipopolysaccharide (LPS). The main finding is that 10 genes (Clec5a, CD14, Fgr, Hck, Anxa1, Lgals3, Irf1, Lbp, Ptx3, Serping1) may represent key molecular links underlying acute activation of immune cells in the hippocampus in response to experimental ischemia. Functional annotation clustering revealed that these genes built the same clusters related to innate immunity/immunity/innate immune response in all MCAO differentially expressed genes and responded to the direct pro-inflammatory stimulus group. The gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses also indicate that LPS-responding genes were the most abundant among the genes related to “positive regulation of tumor necrosis factor biosynthetic process”, “cell adhesion”, “TNF signaling pathway”, and “phagosome” as compared with non-responding ones. In contrast, positive and negative “regulation of cell proliferation” and “HIF-1 signaling pathway” mostly enriched with genes that did not respond to LPS. These results contribute to understanding genomic mechanisms of the impact of immune/inflammatory activation on expression of hippocampal genes after focal brain ischemia.

Quantitative contrast enhanced dual energy CT to predict avascular necrosis: a feasibility study of proximal humerus fractures

BackgroundAvascular necrosis is a delayed complication of proximal humerus fractures that increases the likelihood of poor clinical outcomes. CT scans are routinely performed to guide proximal humerus fracture management. We hypothesized iodine concentration on post-contrast dual energy CT scans identifies subjects who develop avascular necrosis and ischemia due to compromised blood flow.Materials and methods55 patients with proximal humerus fractures enrolled between 2014 and 2017 underwent clinical, radiographic and contrast enhanced dual energy CT assessment. Iodine densities of the humeral head and the glenoid (control) were measured on CT. Subjects managed with open reduction internal fixation or conservatively (non-surgical) were followed for up to two years for radiographic evidence of avascular necrosis. Arthroplasty subjects underwent histopathologic evaluation for ischemia of the resected humeral head.Results17 of 55 subjects (30.9%) were treated conservatively, 21 (38.2%) underwent open reduction internal fixation and 17 of 55 (30.9%) underwent arthroplasty. Of the 38 subjects treated conservatively or with ORIF, 20 (52.6%) completed 12 months of follow up and 14 (36.8%) 24 months of follow up. At 12 months follow up, two of 20 subjects (10%) and at 24 months 3 of 14 subjects (21.4%) developed avascular necrosis. At 12 months, the mean humerus/glenoid iodine ratio was 1.05 (standard deviation 0.24) in subjects with AVN compared to 0.91 (0.24) in those who did not. At 24 months, subjects with avascular necrosis had a mean humerus/glenoid iodine concentration ratio of 1.06 (0.17) compared to 0.924 (0.21) in those who did not. Of 17 arthroplasty subjects, 2 had severe ischemia and an iodine ratio of 1.08 (0.30); 5 had focal ischemia and a ratio of 1.00 (0.36); and 8 no ischemia and a ratio of 0.83 (0.08).ConclusionsQuantifying iodine using dual energy CT in subjects with proximal humerus fractures is technically feasible. Preliminary data suggest higher humeral head iodine concentration may increase risk of avascular necrosis; however, future studies must enroll and follow enough subjects managed with open reduction internal fixation or conservatively for two or more years to provide statistically significant results.Trial Registrations NCT02170545 registered June 23, 2014, ClinicalTrials.gov.

Experimental models in VCID: What are we aiming for?

Vascular contributions to cognitive impairment and dementia (VCID) encompasses the vascular pathology that is evident in most clinical dementia subtypes, as well as vascular dementia as a primary diagnosis. Underlying causes include hypertensive and diabetic disease as well as genetic risk, including monogenic forms of disease (CADASIL, COL4A1 mutations). The most common cause is microvascular: arteriolosclerosis or simple small vessel disease (SVD). SVD is seen radiologically as subcortical ischaemic foci and diffuse white matter hyperintensities on T2-weighted MRI. Pathologically, SVD means fibrotic thickening of deep penetrating arteries within subcortical white matter and deep grey nuclei, accompanied by diffuse changes in surrounding tissue suggestive of hypoperfusion, oedema and vascular fluid leakage. Behaviourally these lesions are associated with cognitive impairment, particularly in executive functions. Current experimental models reflect some of these aspects of VCID (Hainsworth et al. 2017) and are valuable for mechanistic, exploratory and therapeutic studies (Snyder et al. 2016). In vitro systems and transgenic rodent strains are useful for testing the molecular effects of genetic mutations, either as genetic risk factors (APOE knock-ins) or monogenic disease-relevant mutations (NOTCH3, COL4A1, APP). Larger species such as primates, sheep and pigs have more extensive white matter, amenable to imaging. Chronically hypertensive primates exhibit severe cognitive impairment, but lack pathological and radiological features of clinical SVD (Hainsworth et al. 2017). Primates subjected to global cerebral hypoperfusion (up to 28 days) exhibited diffuse white matter damage, microglial activation and fluid leakage (Hainsworth et al. 2017). Domestic pigs made diabetic by the toxin streptozotocin exhibited elevated circulating inflammatory markers, but no brain pathology. Transgenic large animals relevant to VCID have so far not been reported. We aim for preclinical platforms that report: molecular targets in VCID; behavioural measures relevant to VCID; pathological and radiological features of small vessel disease, especially within white matter.

Genome-Wide RNA-Sequencing Reveals Massive Circular RNA Expression Changes of the Neurotransmission Genes in the Rat Brain after Ischemia-Reperfusion.

Ischemic brain stroke is one of the most serious and socially significant diseases. In addition to messenger RNAs (mRNAs), encoding protein, the study of regulatory RNAs in ischemic has exceptional importance for the development of new strategies for neuroprotection. Circular RNAs (circRNAs) have a closed structure, predominantly brain-specific expression, and remain highly promising targets of research. They can interact with microRNAs (miRNAs), diminish their activity and thereby inhibit miRNA-mediated repression of mRNA. Genome-wide RNA-Seq analysis of the subcortical structures of the rat brain containing an ischemic damage focus and penumbra area revealed 395 circRNAs changed their expression significantly at 24 h after transient middle cerebral artery occlusion model (tMCAO) conditions. Furthermore, functional annotation revealed their association with neuroactive signaling pathways. It was found that about a third of the differentially expressed circRNAs (DECs) originate from genes whose mRNA levels also changed at 24 h after tMCAO. The other DECs originate from genes encoding non-regulated mRNAs under tMCAO conditions. In addition, bioinformatic analysis predicted a circRNA–miRNA–mRNA network which was associated with the neurotransmission signaling regulation. Our results show that such circRNAs can persist as potential miRNA sponges for the protection of mRNAs of neurotransmitter genes. The results expanded our views about the neurotransmission regulation in the rat brain after ischemia–reperfusion with circRNA action.

Stenting of ultraembolic hazardous carotid stenotic lesions using the technique of triple antiembolic protection

Objective ‒ to develop a technique of triple antiembolic protection with the simultaneous use of proximal antiembolic protection systems, distal antiembolic filters and two-layer micromesh carotid stents for carotid stenting of ultraembolic hazardous carotid stenosis. Evaluate its effectiveness and safety.Materials and methods. Since 2016, 23 carotid stenting of ultraembolic hazardous carotid stenoses has been performed using the technique of triple antiembolic protection (proximal antiembolic protection systems, distal antiembolic filters and two-layer micromesh carotid stents). All patients had symptomic stenosis: transient ischemic attacks in a certain carotid pool (n = 7), ischemic strokes (n = 16). The age of patients was from 57 to 84 years. Men prevailed among patients (n = 15). Postoperative follow-up included magnetic resonance imaging (MRI) of the brain on the first or second day after surgery with T2*, FLAIR and DWI sequences to determine the presence of «fresh» embolic ischemic foci and to exclude hemorrhagic complications. After 6 months, a control clinical examination, computed tomography or MRI of the brain, ultrasound angioscanning of the main arteries of the head were performed.Results. In all patients the patency of the carotid arteries was completely restored, and in the early postoperative period, no clinical signs of recurrent ischemic brain damage were detected in any of the cases. No signs of plaque prolapse through the stent were detected in any case. A significant amount of atheromatous debris was in 11 cases when aspirated on an external filter. In 3 cases, emboli were also detected in the distal protection filter. This fact indicates that the joint use of distal and proximal antiembolic systems reliably protects against the risk of embolism in such cases. According to MRI on the 1st or 2nd day there were no signs of «fresh» subclinical embolic ischemic foci, as well as hemorrhage. In 20 patients who underwent a follow-up examination, no signs of restenosis in the stent were recorded in any case, as well as repeated ischemic strokes. In 7 cases where the plaque had an ulcer, the ulcer resolved under the stent. Three patients are expected for a follow-up examination. According to the remote survey, these patients do not have new ischemic brain lesions. The effectiveness of the technique of triple antiembolic protection for the treatment of patients with subtotal ultraembolic hazardous carotid stenosis is indicated by the absence of clinical and neuroradiological signs of recurrent ischemic lesions.Conclusions. The technique of triple antiembolic protection for the treatment of patients with subtotal ultraembolic hazardous carotid stenoses is safe and highly effective. It is the improvement of carotid stenting results in this most dangerous group that gives reason to think about revealing the advantages of carotid stenting over carotid endarterectomy in general.

Emergency Carotid Endarterectomy for Internal Carotid Artery Thrombosis in the Course of COVID-19

A case of successful emergency carotid endarterectomy (CEE) in the acute period of ischemic stroke (within an hour after the onset of symptoms) in a patient with acute occlusive thrombosis of the internal carotid artery in the course of moderate-severe COVID-19 with a positive result of the polymerase chain reaction of the nasopharyngeal smear for SARS-CoV-2. The diameter of the ischemic focus in the brain according to multispiral computed tomography did not exceed 2.5 cm. The course of ischemic stroke was characterized by mild neurological deficit (score 5 according to National Institute of Health Stroke Scale). It was demonstrated that the severity of the patient’s condition was associated with bilateral, polysegmental, viral penvmonia with 65% damage to the lung tissue, a decrease in SpO2 to 93%. Laboratory noted coagulopathy with an increase in D-dimer (2837.0 ng/ml), prothrombin according to Quick (155.3%), fibrinogen (14.5 g/l) and signs of a “cytokine storm” with leukocytosis (28.4 10E9/l), an increase in C-reactive protein (183.5 mg/l), ferritin (632.8 ng/ml), interleukin-6 (176.9 pg/ml). The patient underwent glomus-sparing eversional CEE. The intervention was performed under local anesthesia due to the high risk of developing pulmonary barotrauma when using mechanical ventilation. To prevent the development of acute hematoma, a double active drainage was used into the paravasal space and subcutaneous fatty tissue (SFT). In case of thrombosis of one of the drainages, the second could serve as a spare. Also, upon receipt of hemorrhagic discharge from the drainage located in the SFT, the patient would not need to be transported to the operating room. Removal of skin sutures with revision and stitching of the bleeding source could be performed under local anesthesia in a dressing room. The postoperative period was uneventful, with complete regression of neurological symptoms. Used anticoagulant (heparin 5 thousand units 4 times a day s/c) and antiplatelet therapy (acetylsalicylic acid 125 mg at lunch). The patient was discharged from the hospital on the 12th day after CEE in satisfactory condition.

MicroRNA miR-21 Decreases Post-stroke Brain Damage in Rodents.

Due to their role in controlling translation, microRNAs emerged as novel therapeutic targets to modulate post-stroke outcomes. We previously reported that miR-21 is the most abundantly induced microRNA in the brain of rodents subjected to preconditioning-induced cerebral ischemic tolerance. We currently show that intracerebral administration of miR-21 mimic decreased the infarct volume and promoted better motor function recovery in adult male and female C57BL/6 mice subjected to transient middle cerebral artery occlusion. The miR-21 mimic treatment is also efficacious in aged mice of both sexes subjected to focal ischemia. Mechanistically, miR-21 mimic treatment decreased the post-ischemic levels of several pro-apoptotic and pro-inflammatory RNAs, which might be responsible for the observed neuroprotection. We further observed post-ischemic neuroprotection in adult mice administered with miR-21 mimic intravenously. Overall, the results of this study implicate miR-21 as a promising candidate for therapeutic translation after stroke.