Changes in cerebral autoregulation and blood biomarkers after remote ischemic preconditioning

Effect of Remote Ischemic Conditioning on the Form and Function of Red Blood Cells in Patients With Acute Ischemic Stroke

BACKGROUND

Remote ischemic conditioning (RIC) is a simple and low-cost intervention that is thought to increase collateral blood flow through the vasodilatory effects of nitric oxide (NO) produced by the endothelium and red blood cells (RBCs). This study aims to investigate whether RIC affects RBC deformability and levels of NO and nitrite in patients with ischemic stroke.

METHODS

This is a predefined substudy to the RESIST (Remote Ischemic Conditioning in Patients With Acute Stroke Trial) randomized clinical trial conducted in Denmark. RIC was started in the ambulance and continued at the hospital for seven days. Blood samples were collected at different time points: prehospital in the ambulance, in-hospital upon arrival, 2 hours postadmission, and 24 hours postadmission. RBC deformability and erythrocyte aggregation rate were assessed using ektacytometry, NO using flowcytometry, and nitrite content using ozone chemiluminescence.

RESULTS

Of 1500 prehospital randomized patients, 486 patients were included in this study between July 28, 2020, and November 11, 2023, and had blood samples taken. Of these, 249 (51%) had AIS, and here RIC treatment was not associated with increased RBC maximal deformability (RIC, 0.549; sham, 0.548; P=0.31), RBC NO (RIC, 35 301 median fluorescence intensity; sham, 34979 median fluorescence intensity; P=0.89), or nitrite (RIC, 0.036 µmol/L; sham, 0.034 µmol/L; P=0.38), but RIC treatment was associated with a significantly reduced aggregation pressure and a slower erythrocyte aggregation rate (RIC, 323.76 millipascal; sham, 352.74 millipascal; P=0.0113).

CONCLUSIONS

Prehospital and in-hospital RIC significantly reduced erythrocyte aggregation rate in patients with acute ischemic stroke, while there was no change in RBC deformability, NO content, or whole blood nitrite levels.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03481777.

Cerebral autoregulation in patients with acute lacunar infarction: a reliable predictor of outcome

OBJECTIVE

To further investigate the association between dynamic cerebral autoregulation (dCA) and the outcomes in patients with acute lacunar infarction.

METHODS

Patients were prospectively and consecutively enrolled at The First Hospital of Jilin University between 2016 and 2023. dCA was monitored at 1-3 and 7-10 days after the stroke. The outcomes were evaluated using a 3-month modified Rankin Scale score. Binary and ordered logistic regression were employed to analyze the relationship between dCA parameters and outcomes. dCA-based nomogram models were also developed to assess the predictive value of dCA for these patients.

RESULTS

Overall, 332 patients were included in analysis. dCA showed no significant differences between bilateral cerebral hemispheres, as well as two measurement time points (all P > 0.05). Regression analyses showed that dCA at 1-3 and 7-10 days were independently associated with the outcomes of patients with acute lacunar infarction after adjusting for confounders (all P < 0.05). Incorporating dCA parameters into conventional risk factors enhanced the risk-predictive ability of a 3-month unfavorable outcome, significantly improving the area under the receiver operating characteristic curve from 0.798(95% confidence interval [CI], 0.748-0.848) to 0.829(95% CI, 0.783-0.875) (P = 0.046).

INTERPRETATION

dCA remained consistent in bilateral cerebral hemispheres within acute and subacute periods among patients with lacunar infarction. It was independently associated with 3-month outcomes and could be regarded as a reliable predictor for discriminating outcome.

Remote ischaemic conditioning for neurological disorders-a systematic review and narrative synthesis

INTRODUCTION

Remote ischaemic conditioning (RIC) refers to the use of controlled transient ischemic and reperfusion cycles, commonly of the upper or lower limb, to mitigate cellular damage from ischaemic injury. Preclinical studies demonstrate that RIC may have a neuroprotective effect and therefore could represent a novel therapeutic option in the management of neurological disorders. The aim of this review is to comprehensively describe the current clinical evidence of RIC in neurological disorders.

METHODS

A computerised search of EMBASE and OVID MEDLINE was conducted from 2002 to October 2023 for randomised controlled trials (RCTs) investigating RIC in neurological diseases.

RESULTS

A total of 46 different RCTs in 12 different neurological disorders (n = 7544) were included in the analysis. Conditions included acute ischaemic stroke, symptomatic intracranial stenosis and vascular cognitive impairment. The most commonly used RIC protocol parameters in the selected studies were as follows: cuff pressure at 200 mmHg (27 trials), 5-min cycle length (42 trials), 5 cycles of ischaemia and reperfusion (24 trials) and the application to the upper limb unilaterally (23 trials).

CONCLUSIONS

The comprehensive analysis of the included studies reveals promising results regarding the safety and therapeutic effect of RIC as an option for managing neurological diseases. Particularly, the strongest evidence supports its potential use in chronic stroke patients and vascular cognitive impairment. The neuroprotective effects of RIC, as demonstrated in preclinical studies, suggest that this therapeutic approach could extend its benefits to various other diseases affecting the nervous system. However, to establish the efficacy of RIC across different neurological disorders, further trials with larger sample sizes and more diverse patient populations are warranted. Upcoming trials are expected to provide valuable evidence that will not only confirm the efficacy of RIC in neurological disease management but also help identify the most optimal RIC regimen for specific conditions.

Effect of remote ischemic preconditioning on cerebral circulation time in severe carotid artery stenosis: Results from the RIC-CCT trial

In patients with severe internal carotid artery stenosis (sICAS), cerebral circulation time (CCT) is associated with cerebral hyperperfusion syndrome. This study aims to investigate the effect of remote ischemic preconditioning (RIC) on CCT in patients with sICAS. Patients are randomly assigned to the RIC group (RIC twice daily, for 2-4 days before carotid artery stenting [CAS] as an adjunct to standard medical therapy) and the control group. The results show that RIC produces a significant decrease in CCT of the stenosis side (sCCT) from baseline to pre-CAS, and the occurrence of contrast staining on brain computed tomography (CT) is lower in RIC versus control group after CAS. In addition, significant changes in some serum biomarkers suggest that anti-neuroinflammation, anti-oxidative stress, protecting endothelial injury, and improving cerebral autoregulation may be associated with the effect of RIC. These findings provide supporting evidence that RIC can modulate cerebral circulation in patients with sICAS. This study was registered at ClinicalTrials.gov (NCT05451030).

Remote ischemic preconditioning plays a neuroprotective role in cerebral ischemia-reperfusion mice by inhibiting mitophagy

Remote ischemic preconditioning (RIPC) represents a clinically feasible method for safeguarding vital organs against ischemic injury. However, its specific role in cerebral ischemia-reperfusion (I/R) injury remains to be definitively elucidated. In this study, we investigated the neuroprotective effects of RIPC on mice at 7 days post-cerebral I/R and its involvement in mitophagy and mitochondrial dysfunction. Cerebral I/R led to impaired brain function, as well as structural and functional damage to mitochondria. Notably, RIPC treatment ameliorated the neurological dysfunction induced by cerebral I/R. Compared with the I/R group, the expression levels of NeuN, MBP, PDH, and Tom20 were significantly elevated in the RIPC + I/R group. Furthermore, mitochondria in the RIPC + I/R group exhibited more intact structure compared to those in the I/R group. In mice subjected to I/R injury, RIPC treatment markedly increased ATP content, ADP content, TAN level and glucose uptake while upregulating expression levels of Parkin, Pink1 and P62 proteins; it also reduced both the volume of ischemic foci and the number of mitochondrial autophagosomes along with decreasing LC3B II/I ratio. In conclusion, RIPC may exert a neuroprotective role by inhibiting excessive mitophagy during subacute stages following an ischemic stroke.

Remote Ischemic Conditioning to Reduce Perihematoma Edema in Patients with Intracerebral Hemorrhage (RICOCHET): A Randomized Control Trial

Background: Early perihematomal edema (PHE) growth is associated with worse functional outcomes at 90 days. Remote Ischemic conditioning (RIC) may reduce perihematomal inflammation if applied early to patients with intracerebral hemorrhage (ICH). We hypothesize that early RIC, delivered for seven days in patients with spontaneous ICH, may reduce PHE growth. Methods: ICH patients presenting within 6 h of symptom onset and hematoma volume < 60 milliliters (mL) were randomized to an RIC + standard care or standard care (SC) group. The primary outcome measure was calculated edema extension distance (EED), with the cm assessed on day seven. Results: Sixty patients were randomized with a mean  ±  SD age of 57.5  ±  10.8 years, and twenty-two (36.7%) were female. The relative baseline median PHE were similar (RIC group 0.75 (0.5-0.9) mL vs. SC group 0.91 (0.5-1.2) mL, p  =  0.30). The median EEDs at baseline were similar (RIC group 0.58 (0.3-0.8) cm vs. SC group 0.51 (0.3-0.8) cm, p  =  0.76). There was no difference in the median day 7 EED (RIC group 1.1 (0.6-1.2) cm vs. SC group 1 (0.9-1.2) cm, p  =  0.75). Conclusions: Early RIC therapy delivered daily for seven days was feasible. However, no decrease in EED was noted with the intervention.

Cerebral autoregulation: A reliable predictor of prognosis in patients receiving intravenous thrombolysis

AIMS

To investigate the characteristics of dynamic cerebral autoregulation (dCA) after intravenous thrombolysis (IVT) and assess the relationship between dCA and prognosis.

METHODS

Patients with unilateral acute ischemic stroke receiving IVT were prospectively enrolled; those who did not were selected as controls. All patients underwent dCA measurements, by quantifying the phase difference (PD) and gain, at 1-3 and 7-10 days after stroke onset. Simultaneously, two dCA-based nomogram models were established to verify the predictive value of dCA for patients with mild-to-moderate stroke.

RESULTS

Finally, 202 patients who received IVT and 238 who did not were included. IVT was positively correlated with higher PD on days 1-3 and 7-10 after stroke onset. PD values in both sides at 1-3 days after stroke onset and in the affected side at 7-10 days after onset were independent predictors of unfavorable outcomes in patients who received IVT. Additionally, in patients with mild-to-moderate stroke who received IVT, the dCA-based nomogram models significantly improved the risk predictive ability for 3-month unfavorable outcomes.

CONCLUSION

IVT has a positive effect on dCA in patients with acute stroke; furthermore, dCA may be useful to predict the prognosis of patients with IVT.

Remote ischaemic preconditioning for transcatheter aortic valve replacement: a protocol for a systematic review with meta-analysis and trial sequential analysis

INTRODUCTION

Transcatheter aortic valve replacement (TAVR) has become an important treatment in patients with aortic valve disease with the continuous advancement of technology and the improvement of outcomes. However, TAVR-related complications still increase patient morbidity and mortality. Remote ischaemic preconditioning (RIPC) is a simple procedure that provides perioperative protection for many vital organs. However, the efficiency of RIPC on TAVR remains unclear based on inconsistent conclusions from different clinical studies. Therefore, we will perform a protocol for a systematic review and meta-analysis to identify the efficiency of RIPC on TAVR.

METHODS AND ANALYSIS

English databases (PubMed, Web of Science, Ovid Medline, Embase and Cochrane Library), Chinese electronic databases (Wanfang Database, VIP Database and China National Knowledge Infrastructure) and trial registry databases will be searched from inception to December 2023 to identify randomised controlled trials of RIPC on TAVR. We will calculate mean differences or standardised mean differences with 95% CIs for continuous data, and the risk ratio (RR) with 95% CIs for dichotomous data by Review Manager version 5.4. Fixed-effects model or random-effects model will be used according to the degree of statistical heterogeneity assessed by the I-square test. We will evaluate the risk of bias using the Cochrane risk-of-bias tool 2 and assess the evidence quality of each outcome by the Grading of Recommendations Assessment, Development and Evaluation. The robustness of outcomes will be evaluated by trial sequential analysis. In addition, we will evaluate the publication bias of outcomes by Funnel plots and Egger's regression test.

ETHICS AND DISSEMINATION

Ethical approval was not required for this systematic review protocol. The results will be disseminated through peer-reviewed publications.

PROSPERO REGISTRATION NUMBER

CRD42023462926.

Remote ischemic conditioning for stroke: A critical systematic review

Remote ischemic conditioning (RIC) is the application of brief periods of ischemia to an organ or tissue with the aim of inducing protection from ischemia in a distant organ. It was first developed as a cardioprotective strategy but has been increasingly investigated as a neuroprotective intervention. The mechanisms by which RIC achieves neuroprotection are incompletely understood. Preclinical studies focus on the hypothesis that RIC can protect the brain from ischemia reperfusion (IR) injury following the restoration of blood flow after occlusion of a large cerebral artery. However, increasingly, a role of chronic RIC (CRIC) is being investigated as a means of promoting recovery following an ischemic insult to the brain. The recent publication of two large, randomized control trials has provided promise that RIC could improve functional outcomes after acute ischemic stroke, and that there may be a role for CRIC in the prevention of recurrent stroke. Although less developed, there is also proof-of-concept to suggest that RIC may be used to reduce vasospasm after subarachnoid hemorrhage or improve cognitive outcomes in vascular dementia. As a cheap, well-tolerated and almost universally applicable intervention, the motivation for investigating possible benefit of RIC in patients with cerebrovascular disease is great. In this review, we shall review the current evidence for RIC as applied to cerebrovascular disease.

Dynamic Changes and Clinical Significance of Plasma Galectin-3 in Patients with Acute Ischemic Stroke Undergoing Endovascular Therapy

Purpose

Galectin-3 is a key regulator of microglial proliferation and activation and may have dual and time-dependent effects on ischemic stroke. This study aimed to prospectively investigate the dynamic changes in Galectin-3 levels in patients with acute ischemic stroke receiving endovascular therapy and its clinical significance.

Patients and Methods

A total of 105 patients with acute ischemic stroke who underwent endovascular therapy were prospectively enrolled. Plasma Galectin-3 was quantitatively detected by an enzyme-linked immunosorbent assay before the operation and at 1 day, 3 days and 7 days after the operation. A linear mixed-effect model, Pearson correlation analysis and receiver operating characteristic (ROC) curve analysis were used to evaluate the dynamic changes in the plasma Galectin-3 concentration and its relationship with clinical outcomes.

Results

Increases in plasma Galectin-3 levels at 1 day and 3 days after surgery were associated with early neurological deterioration and death (both P <0.05). Increased Galectin-3 levels before surgery and at 1 day and 3 days after surgery were associated with poor prognosis (P <0.05). Pearson correlation analysis revealed that Galectin-3 levels before surgery (r =0.318, P =0.002), at 1 day (r =0.318, P =0.001), 3 days (r =0.429, P < 0.001) and 7 days after surgery (r =0.340, P =0.001) were positively correlated with NIHSS scores. The ROC curve results showed that Galectin-3 concentration had a certain predictive value for death at 1 day (AUC=0.707, P=0.013), 3 days (AUC=0.708, P=0.016) and 7 days after the operation (AUC=0.708, P=0.016), but this predictive value was lower than that of the NIHSS score.

Conclusion

In acute ischemic stroke patients receiving endovascular therapy, an increase in the plasma Galectin-3 levels were associated with death, poor prognosis, and early neurological deterioration. Galectin-3 levels were significantly correlated with the NIHSS score and had a certain predictive value for death.

Helpful to Live Healthier? Intermittent Hypoxic/Ischemic Training Benefits Vascular Homeostasis and Lipid Metabolism with Activating SIRT1 Pathways in Overweight/Obese Individuals

INTRODUCTION

The present study aimed to investigate whether and how normobaric intermittent hypoxic training (IHT) or remote ischemic preconditioning (RIPC) plus normoxic training (RNT) has a synergistic protective effect on lipid metabolism and vascular function compared with normoxic training (NT) in overweight or obese adults.

METHODS

A total of 37 overweight or obese adults (36.03 ± 10.48 years) were randomly assigned to 3 groups: NT group (exercise intervention in normoxia), IHT group (exercise intervention in normobaric hypoxic chamber), and RNT group (exercise intervention in normoxia + RIPC twice daily). All participants carried out the same 1-h exercise intervention for a total of 4 weeks, 5 days per week. Physical fitness parameters were evaluated at pre- and postexercise intervention.

RESULTS

After training, all three groups had a significantly decreased body mass index (p < 0.05). The IHT group had reduced body fat percentage, visceral fat mass (p < 0.05), blood pressure (p < 0.01), left ankle-brachial index (ABI), maximal heart rate (HRmax) (p < 0.05), expression of peroxisome proliferator-activated receptor-γ (PPARγ) (p < 0.01) and increased expression of SIRT1 (p < 0.05), VEGF (p < 0.01). The RNT group had lowered waist-to-hip ratio, visceral fat mass, blood pressure (p < 0.05), and HRmax (p < 0.01).

CONCLUSION

IHT could effectively reduce visceral fat mass and improve vascular elasticity in overweight or obese individuals than pure NT with the activation of SIRT1-related pathways. And RNT also produced similar benefits on body composition and vascular function, which were weaker than those of IHT but stronger than NT. Given the convenience and economy of RNT, both intermittent hypoxic and ischemic training have the potential to be successful health promotion strategies for the overweight/obese population.

Dynamic Cerebral Autoregulation After Carotid Endarterectomy

OBJECTIVE

Studies have shown that dynamic cerebral autoregulation (dCA) is impaired in patients with severe internal carotid artery (ICA) stenosis and that carotid endarterectomy (CEA) may improve dCA in these patients. However, the time course of dCA changes in patients after CEA remains unclear. Therefore, this study aimed to investigate the effects of CEA on the dCA in patients with carotid artery stenosis at different time points.

METHODS

This prospective study enrolled 44 patients (19 symptomatic stenosis patients and 25 asymptomatic stenosis patients) who underwent CEA and 44 age- and sex-matched controls. In the CEA group, the patients underwent dCA measurements at baseline, within 3 days, and 1 month after CEA. Transfer function parameters, phase difference (PD), and gain were used to quantify dCA. Changes in dCA before and after CEA were analyzed in detail.

RESULTS

The bilateral PD of the patients before CEA was significantly lower than that of the control group. This damage did not improve within 3 days after surgery. One month after surgery, the PD on the affected side of the patients significantly improved compared with before surgery and reached the level of the control group. The PD of affected side across time points in symptomatic and asymptomatic stenosis patients is consistent with that in all patients.

CONCLUSIONS

The dCA level did not improve immediately after CEA but significantly improved 1 month after surgery. This suggests that the occurrence of stroke should be considered in the acute period after CEA surgery, and its preventive effect on stroke may be effective after 1 month.

CLINICAL IMPACT

We found the dCA level did not improve immediately after CEA but significantly improved 1 month after surgury. This suggests that the occuttencce of stroke and surgical complications (such as cerebral hyperperfusion syndrome) associated with impaired dCA in the acute phase after CEA surgery should be of particular concern.

Remote limb ischemic postconditioning inhibits microglia pyroptosis by modulating HGF after acute ischemia stroke

The repetitive inflation-deflation of a blood pressure cuff on a limb is known as remote limb ischemic postconditioning (RIPostC). It prevents brain damage induced by acute ischemia stroke (AIS). Pyroptosis, executed by the pore-forming protein gasdermin D (GSDMD), is a type of regulated cell death triggered by proinflammatory signals. It contributes to the pathogenesis of ischemic brain injury. However, the effects of RIPostC on pyroptosis following AIS remain largely unknown. In our study, linear correlation analysis confirmed that serum GSDMD levels in AIS patients upon admission were positively correlated with NIHSS scores. RIPostC treatment significantly reduced GSDMD level compared with patients without RIPostC at 3 days post-treatment. Besides, middle cerebral artery occlusion (MCAO) surgery was performed on C57BL/6 male mice and RIPostC was induced immediately after MCAO. We found that RIPostC suppressed the activation of NLRP3 inflammasome to reduce the maturation of GSDMD, leading to decreased pyroptosis in microglia after AIS. Hepatocyte growth factor (HGF) was identified using the high throughput screening. Importantly, HGF siRNA, exogenous HGF, and ISG15 siRNA were used to reveal that HGF/ISG15 is a possible mechanism of RIPostC regulation in vivo and in vitro.

Changes in cerebral autoregulation, stroke-related blood biomarkers, and autonomic regulation after patent foramen ovale closure in severe migraine patients

AIMS

This study aimed to investigate changes in dynamic cerebral autoregulation (dCA), 20 stroke-related blood biomarkers, and autonomic regulation after patent foramen ovale (PFO) closure in severe migraine patients.

METHODS

Patent foramen ovale severe migraine patients, matched non-PFO severe migraine patients, and healthy controls were included. dCA and autonomic regulation were evaluated in each participant at baseline, and within 48-h and 30 days after closure in PFO migraineurs. A panel of stroke-related blood biomarkers was detected pre-surgically in arterial-and venous blood, and post-surgically in the arterial blood in PFO migraineurs.

RESULTS

Forty-five PFO severe migraine patients, 50 non-PFO severe migraine patients, and 50 controls were enrolled. The baseline dCA function of PFO migraineurs was significantly lower than that of non-PFO migraineurs and controls but was rapidly improved with PFO closure, remaining stable at 1-month follow-up. Arterial blood platelet-derived growth factor-BB (PDGF-BB) levels were higher in PFO migraineurs than in controls, which was immediately and significantly reduced after closure. No differences in autonomic regulation were observed among the three groups.

CONCLUSION

Patent foramen ovale closure can improve dCA and alter elevated arterial PDGF-BB levels in migraine patients with PFO, both of which may be related to the preventive effect of PFO closure on stroke occurrence/recurrence.

Ischemic Preconditioning Provides Neuroprotection by Inhibiting NLRP3 Inflammasome Activation and Cell Pyroptosis

Increasing evidence has demonstrated that ischemic preconditioning (IPC) increases cerebral tolerance to subsequent prolonged ischemic insults. However, the exact mechanisms underlying the process have not been fully explored. In the current study, we aim to investigate whether NLRP3 inflammasome and cell pyroptosis are involved in the neuroprotective mechanism of IPC after ischemic stroke. In vitro, IPC was set up by exposing BV-2 cells to 10 min of oxygen-glucose deprivation (OGD). In vivo, IPC was performed by a transient cerebral ischemia of 10 min occlusion of the middle cerebral artery (MCA) in mice. We found that the NLRP3 inflammasome was activated and cell pyroptosis was induced at 6 h and 24 h post-stroke in an ischemic brain. IPC treatment increased cell viability under OGD state, reduced the infarct size, and attenuated the neurological deficits of mice. However, the effects NLRP3 inflammasome activation and pyroptosis after stroke were attenuated by IPC, which decreased the expression of NLRP3, ASC, cleaved caspase 1, and GSDMD-N and reduced the production of IL-1β and IL-18. In addition, confocal immunofluorescence staining of Annexin V-mCherry and SYTOX green was inhibited by IPC. These findings suggest a more enhanced link between IPC and inflammatory signature and cell death, highlighting that the NLRP3 inflammasome may act as a promising target for the prevention and treatment of ischemic stroke.

Safety and efficacy of remote ischemic conditioning combined with endovascular thrombectomy for acute ischemic stroke due to large vessel occlusion of anterior circulation: A multicenter, randomized, parallel-controlled clinical trial (SERIC-EVT): Study protocol

RATIONALE/AIM

Many patients undergoing successful recanalization after endovascular thrombectomy (EVT) do not have a good outcome; additional neuroprotection might benefit this group. Remote ischemic conditioning (RIC) stimulates endogenous protective mechanisms and may have a neuroprotective in acute brain ischemia. The safety and efficacy of RIC combined with endovascular thrombectomy (SERIC-EVT) trial is investigating the safety and efficacy of RIC for patients with acute ischemic stroke (AIS) who underwent EVT due to large vessel occlusion of the anterior circulation.

METHODS

SERIC-EVT is a multicenter, randomized, parallel-controlled, and blinded endpoint clinical trial. Patients are recruited from 10 hospitals in Jilin Province, Northeast China. Patients with anterior circulation AIS undergoing EVT due to large vessel occlusion are randomized in a 1:1 ratio to RIC or sham-RIC. Participants will receive standard medical treatment and an inflation pressure of 200 mmHg (RIC group) or 60 mmHg (sham-RIC group) twice daily for seven consecutive days.

STUDY OUTCOMES

The primary outcome is the proportion of patients with modified Rankin Scale (mRS) score of 0-2 on day 90. Secondary outcome measures include the National Institute of Health Stroke Scale, Barthel Index, and mRS scores obtained at 24 h, 7 days, 30 ± 3 days, and 90 ± 3 days post-EVT, recanalization rate, expanded Thrombolysis in Cerebral Infarction score, and symptomatic intracranial hemorrhage post-EVT. Mortality and all adverse events, including skin changes and pain scores, within the first 90 days will be used as safety outcome measures.

SAMPLE SIZE ESTIMATES

Based on previous studies, we estimate a 14% difference in functional independence (the mRS ⩽2) between RIC and sham-RIC groups. Considering a significance level of 5% and power of 80%, and one-fifth of patients lost to follow up, the planned sample size is 498 patients (249 per group).

DISCUSSION

RIC might be a strategy that improves 3-month clinical outcomes in AIS patients who have undergone EVT due to large vessel occlusion of anterior circulation. SERIC-EVT will determine whether this is the case.

Safety and efficacy of remote ischemic conditioning combined with intravenous thrombolysis for acute ischemic stroke: A multicenter, randomized, parallel-controlled clinical trial (SERIC-IVT) Study design and protocol

RATIONALE

Remote ischemic conditioning (RIC) combined with intravenous thrombolysis (IVT) may improve functional outcomes in patients with acute ischemic stroke (AIS).

AIM

To assess the efficacy and safety of RIC combined with IVT for AIS.

METHODS AND DESIGN

SERIC-IVT is a multicenter, randomized, parallel-controlled, blinded endpoint clinical trial. A total of 558 patients with AIS who underwent IVT therapy will be randomly assigned 1:1 to receive RIC or sham-RIC plus standard medical therapy. The cuff pressures of the RIC group and the sham-RIC group will be 200 mm Hg and 60 mm Hg, respectively, performed twice a day for seven consecutive days.

STUDY OUTCOMES

The primary efficacy outcome is the proportion of patients with a favorable functional outcome as defined as a modified Rankin Scale ⩽ 1 at 90 days. Safety outcomes include mortality and adverse events within 90 days.

SAMPLE SIZE ESTIMATES

A sample size of 558 patients with AIS (279 in each group) will allow detection of a shift of 13.14% toward favorable functional outcome at 90 days (modified Rankin Scale ⩽ 1) with 5% significance and 80% power.

DISCUSSION

RIC is a promising adjuvant treatment for AIS. SERIC-IVT will inform on whether RIC treatment combined with IVT improves functional outcomes in AIS patients and identify any safety issues.

Dynamic changes in the glycocalyx and clinical outcomes in patients undergoing endovascular treatments for large vessel occlusion

Purpose

We aimed to verify the prognostic value of the glycocalyx as a marker of blood-brain barrier damage in patients with acute ischemic stroke undergoing endovascular therapy.

Methods

We recruited patients with large vessel occlusion who were undergoing recanalization and tested their glycocalyx at multiple time points. On the basis of the 90-day follow-up data, the patients were divided into a survivor group and a nonsurvivor group. In addition, neurological function was tracked, and patients were divided into a neurological deterioration group and a group without neurological deterioration. Associations between outcomes and dynamic changes in the glycocalyx were determined using a linear mixed model, and significant factors were used as covariates.

Results

Nonsurvivors and patients with neurological deterioration had significantly higher syndecan-1 concentrations than survivors and patients without neurological deterioration, and syndecan-1 tended to decline after endovascular therapy (p < 0.05). The increased level of syndecan-1 at 36 h after endovascular treatment was positively correlated with the National Institute of Health Stroke Scale score for neurological deterioration (r = 0.702, p = 0.005). However, there was no significant difference in the level of hyaluronic acid or heparan sulfate in the plasma of patients with different clinical outcomes.

Conclusion

Pre-reperfusion syndecan-1 levels in patients with large vessel occlusion stroke are associated with 90-day mortality and the re-degradation of syndecan-1 is positively associated with neurological deterioration.

Non-pharmacological interventions for vascular health and the role of the endothelium

The most common non-pharmacological intervention for both peripheral and cerebral vascular health is regular physical activity (e.g., exercise training), which improves function across a range of exercise intensities and modalities. Numerous non-exercising approaches have also been suggested to improved vascular function, including repeated ischemic preconditioning (IPC); heat therapy such as hot water bathing and sauna; and pneumatic compression. Chronic adaptive responses have been observed across a number of these approaches, yet the precise mechanisms that underlie these effects in humans are not fully understood. Acute increases in blood flow and circulating signalling factors that induce responses in endothelial function are likely to be key moderators driving these adaptations. While the impact on circulating factors and environmental mechanisms for adaptation may vary between approaches, in essence, they all centre around acutely elevating blood flow throughout the circulation and stimulating improved endothelium-dependent vascular function and ultimately vascular health. Here, we review our current understanding of the mechanisms driving endothelial adaptation to repeated exposure to elevated blood flow, and the interplay between this response and changes in circulating factors. In addition, we will consider the limitations in our current knowledge base and how these may be best addressed through the selection of more physiologically relevant experimental models and research. Ultimately, improving our understanding of the unique impact that non-pharmacological interventions have on the vasculature will allow us to develop superior strategies to tackle declining vascular function across the lifespan, prevent avoidable vascular-related disease, and alleviate dependency on drug-based interventions.

Effects of remote ischemic conditioning on cognitive performance: A systematic review

The aging process leads to subtle decline in cognitive function, and in some overt dementia. Like physical activity Remote Ischemic Conditioning (RIC) may ameliorate these changes on cognitive impairment in humans. The purpose of this study was to compared the effects of single, repeated short-term and long-term treatment RIC, and analyze its effect registered as immediate vs. long-term on cognitive performance in humans. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and was registered with PROSPERO, number (CRD42021285668). A systematic review was conducted to identify relevant studies through six healthcare science databases (Cochrane, PubMed, EMBASE, EBSCO, Scopus, and Web of Science) up to December 2021. Eligibility criteria included (1) a study sample of participants aged ≥18 years, (2) post-intervention changes on cognitive performance in humans, and (3) this systematic review included only randomized controlled trials of RIC in humans. The quality of the included studies was assessed by GRADEpro tool. A total of 118 articles were initially identified, 35 of which met the inclusion criteria. Based on title/abstract, age and RIC protocol, 14 articles were included in this review: 5 studies investigated the immediate and long-term effect of a single RIC (n = 370 patients), 4 studies examined intermittent short-term RIC (n = 174 patients) and 5 studies evaluated repeated long-term RIC (n = 228 patients). A single pre-operative RIC treatment had an immediate effect that disappeared at one week. Short-term RIC showed either a positive or no effects on cognitive function. The majority of studies examining long-term RIC treatment showed improvements in cognitive performance, particularly in very old adults and older patients with cognitive impairments. Single RIC treatment did not show any persisting effect on cognition. However, repeated short term RIC showed some improvement and long-term RIC may improve cognitive performance after stroke or enhance neuropsychological tests in patients diagnosed with vascular dementia. The mixed results might be explained by different RIC treatment protocols and populations investigated.

Non-pharmacological interventions for vascular health and the role of the endothelium

The most common non-pharmacological intervention for both peripheral and cerebral vascular health is regular physical activity (e.g., exercise training), which improves function across a range of exercise intensities and modalities. Numerous non-exercising approaches have also been suggested to improved vascular function, including repeated ischemic preconditioning (IPC); heat therapy such as hot water bathing and sauna; and pneumatic compression. Chronic adaptive responses have been observed across a number of these approaches, yet the precise mechanisms that underlie these effects in humans are not fully understood. Acute increases in blood flow and circulating signalling factors that induce responses in endothelial function are likely to be key moderators driving these adaptations. While the impact on circulating factors and environmental mechanisms for adaptation may vary between approaches, in essence, they all centre around acutely elevating blood flow throughout the circulation and stimulating improved endothelium-dependent vascular function and ultimately vascular health. Here, we review our current understanding of the mechanisms driving endothelial adaptation to repeated exposure to elevated blood flow, and the interplay between this response and changes in circulating factors. In addition, we will consider the limitations in our current knowledge base and how these may be best addressed through the selection of more physiologically relevant experimental models and research. Ultimately, improving our understanding of the unique impact that non-pharmacological interventions have on the vasculature will allow us to develop superior strategies to tackle declining vascular function across the lifespan, prevent avoidable vascular-related disease, and alleviate dependency on drug-based interventions.

Safety and Feasibility Assessment of Repetitive Vascular Occlusion Stimulus (RVOS) Application to Multi-Organ Failure Critically Ill Patients: A Pilot Randomised Controlled Trial

Muscle wasting is implicated in the pathogenesis of intensive care unit acquired weakness (ICU-AW), affecting 40% of patients and causing long-term physical disability. A repetitive vascular occlusion stimulus (RVOS) limits muscle atrophy in healthy and orthopaedic subjects, thus, we explored its application to ICU patients. Adult multi-organ failure patients received standard care +/- twice daily RVOS {4 cycles of 5 min tourniquet inflation to 50 mmHg supra-systolic blood pressure, and 5 min complete deflation} for 10 days. Serious adverse events (SAEs), tolerability, feasibility, acceptability, and exploratory outcomes of the rectus femoris cross-sectional area (RFCSA), echogenicity, clinical outcomes, and blood biomarkers were assessed. Only 12 of the intended 32 participants were recruited. RVOS sessions (76.1%) were delivered to five participants and two could not tolerate it. No SAEs occurred; 75% of participants and 82% of clinical staff strongly agreed or agreed that RVOS is an acceptable treatment. RFCSA fell significantly and echogenicity increased in controls (n = 5) and intervention subjects (n = 4). The intervention group was associated with less frequent acute kidney injury (AKI), a greater decrease in the total sequential organ failure assessment score (SOFA) score, and increased insulin-like growth factor-1 (IGF-1), and reduced syndecan-1, interleukin-4 (IL-4) and Tumor necrosis factor receptor type II (TNF-RII) levels. RVOS application appears safe and acceptable, but protocol modifications are required to improve tolerability and recruitment. There were signals of possible clinical benefit relating to RVOS application.

Remote ischaemic preconditioning - translating cardiovascular benefits to humans

Remote ischaemic preconditioning (RIPC), induced by intermittent periods of limb ischaemia and reperfusion, confers cardiac and vascular protection from subsequent ischaemia–reperfusion (IR) injury. Early animal studies reliably demonstrate that RIPC attenuated infarct size and preserved cardiac tissue. However, translating these adaptations to clinical practice in humans has been challenging. Large clinical studies have found inconsistent results with respect to RIPC eliciting IR injury protection or improving clinical outcomes. Follow‐up studies have implicated several factors that potentially affect the efficacy of RIPC in humans such as age, fitness, frequency, disease state and interactions with medications. Thus, realizing the clinical potential for RIPC may require a human experimental model where confounding factors are more effectively controlled and underlying mechanisms can be further elucidated. In this review, we highlight recent experimental findings in the peripheral circulation that have added valuable insight on the mechanisms and clinical benefit of RIPC in humans. Central to this discussion is the critical role of timing (i.e. immediate vs. delayed effects following a single bout of RIPC) and the frequency of RIPC. Limited evidence in humans has demonstrated that repeated bouts of RIPC over several days uniquely improves vascular function beyond that observed with a single bout alone. Since changes in resistance vessel and microvascular function often precede symptoms and diagnosis of cardiovascular disease, repeated bouts of RIPC may be promising as a preclinical intervention to prevent or delay cardiovascular disease progression.

The Impact of Serial Remote Ischemic Conditioning on Dynamic Cerebral Autoregulation and Brain Injury Related Biomarkers

Objective

Recent studies have demonstrated the positive roles of remote ischemic conditioning (RIC) in patients with cerebrovascular diseases; however, the mechanisms remain unclear. This study aimed to explore the effect of serial RIC on dynamic cerebral autoregulation (dCA) and serum biomarkers associated with brain injury, both of which are related to the prognosis of cerebrovascular disease.

Methods

This was a self-controlled interventional study in healthy adults. The RIC was conducted twice a day for 7 consecutive days (d1–d7) and comprised 4 × 5-min single arm cuff inflation/deflation cycles at 200 mmHg. All participants underwent assessments of dCA ten times, including baseline, d1, d2, d4, d7, d8, d10, d14, d21, and d35 of the study. Blood samples were collected four times (baseline, d1, d7, and d8) immediately after dCA measurements. The transfer function parameters [phase difference (PD) and gain] were used to quantify dCA. Four serum biomarkers associated with brain injury, ubiquitin C-terminal hydrolase-L1, neuron-specific enolase, glial fibrillary acidic protein, and S100β were tested.

Results

Twenty-two healthy adult volunteers (mean age 25.73 ± 1.78 years, 3 men [13.6%], all Asian) were enrolled in this study. Bilateral PD values were significantly higher since four times of RIC were completed (d2) compared with PD values at baseline (left: 53.31 ± 10.53 vs. 45.87 ± 13.02 degree, p = 0.015; right: 54.90 ± 10.46 vs. 45.96 ± 10.77 degree, p = 0.005). After completing 7 days of RIC, the significant increase in dCA was sustained for at least 28 days (d35, left: 53.11 ± 14.51 degree, P = 0.038; right: 56.95 ± 14.57 degree, p < 0.001). No difference was found in terms of different serum biomarkers related to brain injury before and after RIC.

Conclusion

The elevation in dCA was detected immediately after four repeated times of RIC, and 7-day consecutive RIC induced a sustained increase in dCA for at least 28 days and did not affect blood biomarkers of brain injury in healthy adults. These results will help us to formulate detailed strategies for the safe and effective application of RIC in patients with cerebrovascular disease.

Immune Modulation as a Key Mechanism for the Protective Effects of Remote Ischemic Conditioning After Stroke

Remote ischemic conditioning (RIC), which involves a series of short cycles of ischemia in an organ remote to the brain (typically the limbs), has been shown to protect the ischemic penumbra after stroke and reduce ischemia/reperfusion (IR) injury. Although the exact mechanism by which this protective signal is transferred from the remote site to the brain remains unclear, preclinical studies suggest that the mechanisms of RIC involve a combination of circulating humoral factors and neuronal signals. An improved understanding of these mechanisms will facilitate translation to more effective treatment strategies in clinical settings. In this review, we will discuss potential protective mechanisms in the brain and cerebral vasculature associated with RIC. We will discuss a putative role of the immune system and circulating mediators of inflammation in these protective processes, including the expression of pro-and anti-inflammatory genes in peripheral immune cells that may influence the outcome. We will also review the potential role of extracellular vesicles (EVs), biological vectors capable of delivering cell-specific cargo such as proteins and miRNAs to cells, in modulating the protective effects of RIC in the brain and vasculature.

Reproducibility and diurnal variation of the directional sensitivity of the cerebral pressure-flow relationship in men and women

The cerebral pressure-flow relationship has directional sensitivity, meaning the augmentation in cerebral blood flow is attenuated when mean arterial pressure (MAP) increases vs MAP decreases. We employed repeated squat-stands (RSS) to quantify it using a novel metric. However, its within-day reproducibility and the impacts of diurnal variation and biological sex are unknown. Study aims were to evaluate this metric for: 1) within-day reproducibility and diurnal variation in middle (MCA; ∆MCAv_T/∆MAP_T) and posterior cerebral arteries (PCA; ∆PCAv_T/∆MAP_T); 2) sex differences. ∆MCAv_T/∆MAP_T and ∆PCAv_T/∆MAP_T were calculated at seven time-points (08:00-17:00) in 18 participants (8 women; 24 ± 3 yrs) using the minimum-to-maximum MCAv or PCAv and MAP for each RSS at 0.05 Hz and 0.10 Hz. Relative metric values were also calculated (%MCAv_T/%MAP_T, %PCAv_T/%MAP_T). Intraclass correlation coefficient (ICC) evaluated reproducibility, which was good (0.75-0.90) to excellent (>0.90). Time-of-day impacted ∆MCAv_T/∆MAP_T (0.05 Hz: p = 0.002; 0.10 Hz: p = 0.001), %MCAv_T/%MAP_T (0.05 Hz: p = 0.035; 0.10 Hz: p = 0.009), and ∆PCAv_T/∆MAP_T (0.05 Hz: p = 0.024), albeit with small/negligible effect sizes. MAP direction impacted both arteries' metric at 0.10 Hz (all p < 0.024). Sex differences in the MCA only (p = 0.003) vanished when reported in relative terms. These findings demonstrate this metric is reproducible throughout the day in the MCA and PCA and is not impacted by biological sex.

Pharmacologic Inhibition of Pain Response to Incomplete Vascular Occlusion Blunts Cardiovascular Preconditioning Response

Complete vascular occlusion to distant tissue prior to an ischemic cardiac event can provide significant cardioprotection via remote ischemic preconditioning (RIPC). Despite understanding its mechanistic basis, its translation to clinical practice has been unsuccessful, likely secondary to the inherent impossibility of predicting (and therefore preconditioning) an ischemic event, as well as the discomfort that is associated with traditional, fully occlusive RIPC stimuli. Our laboratory has previously shown that non-occlusive banding (NOB) via wrapping of a leather band (similar to a traditional Jewish ritual) can elicit an RIPC response in healthy human subjects. This study sought to further the pain-mediated aspect of this observation in a mouse model of NOB with healthy mice that were exposed to treatment with and without lidocaine to inhibit pain sensation prior to ischemia/reperfusion injury. We demonstrated that NOB downregulates key inflammatory markers resulting in a preconditioning response that is partially mediated via pain sensation.

Hypoxia Tolerant Species: The Wisdom of Nature Translated into Targets for Stroke Therapy

Human neurons rapidly die after ischemia and current therapies for stroke management are limited to restoration of blood flow to prevent further brain damage. Thrombolytics and mechanical thrombectomy are the available reperfusion treatments, but most of the patients remain untreated. Neuroprotective therapies focused on treating the pathogenic cascade of the disease have widely failed. However, many animal species demonstrate that neurons can survive the lack of oxygen for extended periods of time. Here, we reviewed the physiological and molecular pathways inherent to tolerant species that have been described to contribute to hypoxia tolerance. Among them, Foxo3 and Eif5A were reported to mediate anoxic survival in Drosophila and Caenorhabditis elegans, respectively, and those results were confirmed in experimental models of stroke. In humans however, the multiple mechanisms involved in brain cell death after a stroke causes translation difficulties to arise making necessary a timely and coordinated control of the pathological changes. We propose here that, if we were able to plagiarize such natural hypoxia tolerance through drugs combined in a pharmacological cocktail it would open new therapeutic opportunities for stroke and likely, for other hypoxic conditions.

Impaired dynamic cerebral autoregulation in young adults with mild depression

The incidence of depression is increasing, especially in the young adult population. Impaired cognitive function is one of the characteristics of depression, which may be related to impaired cerebral autoregulation (CA). We investigated the characteristics of CA in young adults with mild depression, as well as its validity for identifying patients with depression. Patients (aged 18-35 years) with Hamilton Depression Rating Scale (HAMD) scores ranging from 8 to 17 and a first episode of mild depression were enrolled in this study. Healthy volunteers were recruited as controls. Noninvasive continuous arterial blood pressure and bilateral middle cerebral artery blood flow velocity were simultaneously recorded from each subject. Transfer function analysis was applied to derive phase difference, gain, coherence and rate of recovery for the assessment of CA. Forty-three patients and 43 healthy controls were enrolled. Phase difference values were significantly compromised in young adults with mild depression and were negatively correlated with HAMD scores. Rate of recovery values estimated from depressed patients was significantly lower. The validity in identifying patients with depression was favorable for the phase difference. The cutoff phase difference value was 29.66. Our findings suggest that dynamic CA was impaired in young patients with mild depression and negatively correlated with HAMD scores. CA represented by phase difference can be used as an objective auxiliary examination of depression, and has clinical diagnostic value for the early identification of patients with depression.

Improvement of exhausted cerebral autoregulation in patients with idiopathic intracranial hypertension benefit of venous sinus stenting

Objective.To evaluate the cerebral autoregulation (CA) in idiopathic intracranial hypertension (IIH) patients with transfer function analysis, and to explore its improvement after venous sinus stenting.Approach. In total, 15 consecutive IIH patients with venous sinus stenosis and 15 controls were recruited. All the patients underwent digital subtraction angiography and venous manometry. Venous sinus stenting was performed for IIH patients with a trans-stenosis pressure gradient ≥8 mmHg. CA was assessed before and after the operation with transfer function analysis, by using the spontaneous oscillations of the cerebral blood flow velocity in the bilateral middle cerebral artery and blood pressure.Main results. Compared with controls, the autoregulatory parameters, phase shift and rate of recovery, were both significantly lower in IIH patients [(57.94° ± 23.22° versus 34.59° ± 24.15°,p < 0.001; (39.87 ± 21.95) %/s versus (20.56 ± 46.66) %/s,p= 0.045, respectively). In total, six patients with bilateral transverse or sigmoid sinus stenosis received venous sinus stenting, in whom, the phase shift significantly improved after venous sinus stenting (39.62° ± 20.26° versus 22.79° ± 19.96°,p = 0.04).Significance. The study revealed that dynamic CA was impaired in IIH patients and was improved after venous sinus stenting. CA assessment has the potential to be used for investigating the hemodynamics in IIH patients.

Therapeutic Potential of Remote Ischemic Conditioning in Vascular Cognitive Impairment

Vascular cognitive impairment (VCI) is a heterogeneous disease caused by a variety of cerebrovascular diseases. Patients with VCI often present with slower cognitive processing speed and poor executive function, which affects their independence in daily life, thus increasing social burden. Remote ischemic conditioning (RIC) is a non-invasive and efficient intervention that triggers endogenous protective mechanisms to generate neuroprotection. Over the past decades, evidence from basic and clinical research has shown that RIC is promising for the treatment of VCI. To further our understanding of RIC and improve the management of VCI, we summarize the evidence on the therapeutic potential of RIC in relation to the risk factors and pathobiologies of VCI, including reducing the risk of recurrent stroke, decreasing high blood pressure, improving cerebral blood flow, restoring white matter integrity, protecting the neurovascular unit, attenuating oxidative stress, and inhibiting the inflammatory response.

Remote ischaemic conditioning for stroke: unanswered questions and future directions

Remote ischaemic conditioning (RIC) refers to a process whereby periods of intermittent ischaemia, typically via the cyclical application of a blood pressure cuff to a limb at above systolic pressure, confers systemic protection against ischaemia in spatially distinct vascular territories. The mechanisms underlying this have not been characterised fully but have been shown to involve neural, hormonal and systemic inflammatory signalling cascades. Preclinical and early clinical studies have been promising and suggest beneficial effects of RIC in acute ischaemic stroke, symptomatic intracranial stenosis and vascular cognitive impairment. Through systematic searches of several clinical trials databases we identified 48 active clinical trials of RIC in ischaemic stroke, intracerebral haemorrhage and subarachnoid haemorrhage. We summarise the different RIC protocols and outcome measures studied in ongoing clinical trials and highlight which studies are most likely to elucidate the underlying biological mechanisms of RIC and characterise its efficacy in the near future. We discuss the uncertainties of RIC including the optimal frequency and duration of therapy, target patient groups, cost-effectiveness, the confounding impact of medications and the absence of a clinically meaningful biomarker of the conditioning response. With several large clinical trials of RIC expected to report their outcomes within the next 2 years, this review aims to highlight the most important studies and unanswered questions that will need to be addressed before this potentially widely accessible and low-cost intervention can be used in clinical practice.

Effect of remote ischemic preconditioning on cerebral vasospasm, biomarkers of cerebral ischemia, and functional outcomes in aneurysmal subarachnoid hemorrhage (ERVAS): A randomized controlled pilot trial

BACKGROUND:

Cerebral vasospasm can complicate aneurysmal subarachnoid hemorrhage (aSAH), contributing to cerebral ischemia. We explored the role of remote ischemic preconditioning (RIPC) in reducing cerebral vasospasm and ischemia and improving outcomes after aSAH.

MATERIALS AND METHODS:

Patients with ruptured cerebral aneurysm undergoing surgical clipping and meeting the trial criteria were randomized to true RIPC (n = 13) (inflating upper extremity blood pressure cuff thrice to 30 mmHg above systolic pressure for 5 min) or sham RIPC (n = 12) (inflating blood pressure cuff thrice to 30 mmHg for 5 min) after ethical approval. A blinded observer assessed outcome measures-cerebral vasospasm and biomarkers of cerebral ischemia. We also evaluated the feasibility and safety of RIPC in aSAH and Glasgow Outcome Scale-Extended (GOSE).

RESULTS:

Angiographic vasospasm was seen in 9/13 (69%) patients; 1/4 patients (25%) in true RIPC group, and 8/9 patients (89%) in sham RIPC group (P = 0.05). Vasospasm on transcranial Doppler study was diagnosed in 5/25 (20%) patients and 1/13 patients (7.7%) in true RIPC and 4/12 patients (33.3%) in sham RIPC group, (P = 0.16). There was no difference in S100B and neuron-specific enolase (NSE) levels over various time-points within groups (P = 0.32 and 0.49 for S100B, P = 0.66 and 0.17 for NSE in true and sham groups, respectively) and between groups (P = 0.56 for S100B and P = 0.31 for NSE). Higher GOSE scores were observed with true RIPC (P = 0.009) unlike sham RIPC (P = 0.847) over 6-month follow-up with significant between group difference (P = 0.003). No side effects were seen with RIPC.

CONCLUSIONS:

RIPC is feasible and safe in patients with aSAH and results in a lower incidence of vasospasm and better functional outcome.

Blood markers in remote ischaemic conditioning for acute ischaemic stroke: data from the REmote ischaemic Conditioning After Stroke Trial

BACKGROUND AND PURPOSE

Remote ischaemic per-conditioning (RIC) is neuroprotective in experimental ischaemic stroke. Several neurohumoral, vascular and inflammatory mediators are implicated. The effect of RIC on plasma biomarkers was assessed using clinical data from the REmote ischaemic Conditioning After Stroke Trial (RECAST-1).

METHODS

RECAST-1 was a pilot sham-controlled blinded trial in 26 patients with ischaemic stroke, randomized to receive four 5-min cycles of RIC within 24 h of ictus. Plasma taken pre-intervention, immediately post-intervention and on day 4 was analysed for nitric oxide (nitrate/nitrite) using chemiluminescence and all other biomarkers by multiplex analysis. Biomarkers were correlated with clinical outcome (day 90 National Institutes of Health Stroke Scale, modified Rankin Scale, Barthel index).

RESULTS

Remote ischaemic per-conditioning reduced serum amyloid protein (SAP) and tissue necrosis factor α (TNF-α) levels from pre- to post-intervention (n = 13, two-way ANOVA, p < 0.05). Overall (n = 26), increases in SAP pre- to post-intervention and pre-intervention to day 4 were moderately correlated with worse day 90 clinical outcomes. No consistent significant changes over time, or by treatment, or correlations with outcome were seen for other biomarkers.

CONCLUSIONS

Remote ischaemic per-conditioning reduced SAP and TNF-α levels from pre- to post-intervention. Increases in plasma levels of SAP were associated with worse clinical outcomes after ischaemic stroke. Larger studies assessing biomarkers and the safety and efficacy of RIC in acute ischaemic stroke are warranted to further understand these relationships.

The effect of remote ischaemic conditioning on blood pressure response: A systematic review and meta-analysis

BACKGROUND

Previous work has evaluated the effect of remote ischaemic conditioning (RIC) in a number of clinical conditions (e.g. cardiac surgery and acute kidney injury), but only one analysis has examined blood pressure (BP) changes. While individual studies have reported the effects of acute bouts and repeated RIC exposure on resting BP, efficacy is equivocal. We conducted a systematic review and meta-analysis to evaluate the effects of acute and repeat RIC on BP.

METHODS

A systematic search was performed using PubMed, Web of Science, EMBASE, and Cochrane Library of Controlled Trials up until October 31, 2020. Additionally, manual searches of reference lists were performed. Studies that compared BP responses after exposing participants to either an acute bout or repeated cycles of RIC with a minimum one-week intervention period were considered.

RESULTS

Eighteen studies were included in this systematic review, ten examined acute effects while eight investigated repeat effects of RIC. Mean differences (MD) for outcome measures from acute RIC studies were: systolic BP 0.18 mmHg (95%CI -0.95, 1.31; p = 0.76), diastolic BP -0.43 mmHg (95%CI -2.36, 1.50; p = 0.66), MAP -1.73 mmHg (95%CI -3.11, -0.34; p = 0.01) and HR -1.15 bpm (95%CI -2.92, 0.62; p = 0.20). Only MAP was significantly reduced. Repeat RIC exposure showed non-significant change in systolic BP -3.23 mmHg (95%CI -6.57, 0.11; p = 0.06) and HR -0.16 bpm (95%CI -7.08, 6.77; p = 0.96) while diastolic BP -2.94 mmHg (95%CI -4.08, -1.79; p < 0.00001) and MAP -3.21 mmHg (95%CI -4.82, -1.61; p < 0.0001) were significantly reduced.

CONCLUSIONS

Our data suggests repeated, but not acute, RIC produced clinically meaningful reductions in diastolic BP and MAP.

Receptors, Channel Proteins, and Enzymes Involved in Microglia-mediated Neuroinflammation and Treatments by Targeting Microglia in Ischemic Stroke

Stroke is the largest contributor to global neurological disability-adjusted life-years, posing a huge economic and social burden to the world. Though pharmacological recanalization with recombinant tissue plasminogen activator and mechanical thrombectomy have greatly improved the prognosis of patients with ischemic stroke, clinically, there is still no effective treatment for the secondary injury caused by cerebral ischemia. In recent years, more and more evidences show that neuroinflammation plays a pivotal role in the pathogenesis and progression of ischemic cerebral injury. Microglia are brain resident innate immune cells and act the role peripheral macrophages. They play critical roles in mediating neuroinflammation after ischemic stroke. Microglia-mediated neuroinflammation is not an isolated process and has complex relationships with other pathophysiological processes as oxidative/nitrative stress, excitotoxicity, necrosis, apoptosis, pyroptosis, autophagy, and adaptive immune response. Upon activation, microglia differentially express various receptors, channel proteins, and enzymes involved in promoting or inhibiting the inflammatory processes, making them the targets of intervention for ischemic stroke. To inhibit microglia-related neuroinflammation and promote neurological recovery after ischemic stroke, numerous biochemical agents, cellular therapies, and physical methods have been demonstrated to have therapeutic potentials. Though accumulating experimental evidences have demonstrated that targeting microglia is a promising approach in the treatment of ischemic stroke, the clinical progress is slow. Till now, no clinical study could provide convincing evidence that any biochemical or physical therapies could exert neuroprotective effect by specifically targeting microglia following ischemic stroke.

Impaired cerebral autoregulation is associated with poststroke cognitive impairment

Objective

To investigate whether dynamic cerebral autoregulation (CA) and neuroimaging characteristics are determinants of poststroke cognitive impairment (PSCI).

Methods

Eighty patients within 7 days of acute ischemic stroke and 35 age‐ and sex‐matched controls were enrolled. In the patients with stroke, brain magnetic resonance imaging and dynamic CA were obtained at baseline, and dynamic CA was followed up at 3 months and 1 year. Montreal Cognitive Assessment (MoCA) was performed at 3 months and 1 year. Patients with a MoCA score <23 at 1 year were defined as having PSCI, and those with a MoCA score that decreased by 2 points or more between the 3‐month and 1‐year assessments were defined as having progressive cognitive decline.

Results

In total, 65 patients completed the study and 16 developed PSCI. The patients with PSCI exhibited poorer results for all cognitive domains than did those without PSCI. The patients with PSCI also had poorer CA (lower phase shift between cerebral blood flow and blood pressure waveforms in the very low frequency band) compared with that of the patients without PSCI and controls at baseline and 1 year. CA was not different between the patients without PSCI and controls. In the multivariate analysis, low education level, lobar microbleeds, and impaired CA (very low frequency phase shift [≤46°] within 7 days of stroke), were independently associated with PSCI. In addition, impaired CA was associated with progressive cognitive decline.

Interpretation

Low education level, lobar microbleeds, and impaired CA are involved in the pathogenesis of PSCI.

Remote liver ischaemic preconditioning protects rat brain against cerebral ischaemia-reperfusion injury by activation of an AKT-dependent pathway

NEW FINDINGS

What is the central question of this study? Can remote liver ischaemic preconditioning (RLIPC) protect rat brain against cerebral ischaemia-reperfusion injury? What is the main finding and its importance? Pretreatment with RLIPC reduced cerebral infarct volume, improved neurological outcomes and inhibited neuron apoptosis. RLIPC led to increased phosphorylation of AKT, while inhibition of AKT abolished the effects of RLIPC. Our data suggest that liver ischaemic preconditioning exerts a strong neuroprotective effect against cerebral ischaemia-reperfusion injury by activating an AKT-dependent pathway.

ABSTRACT

Remote limb ischaemic preconditioning has been shown to have beneficial effects in protecting brains against ischaemia-reperfusion (I/R) injury. However, little is known regarding the effect of remote liver ischaemic conditioning (RLIPC). We therefore investigated the effect of RLIPC on brain tissues suffering from I/R injury. Rats were randomly assigned to a sham group, a control group or a RLIPC group. Rats in all groups except for the sham group received middle cerebral artery occlusion (MCAO) for 1 h, followed by 48 h of reperfusion. For the RLIPC rats, four cycles of 5 min of liver ischaemia (portal vein, hepatic arterial and venous trunk occlusion) with 5 min intermittent reperfusion were carried out before cerebral ischaemia. Infarct volume was assessed after 48 h of reperfusion. Blood samples were taken for serum lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) tests. Morphological changes of cortical tissue and cellular apoptosis were determined. Right cortex tissues were taken for western blotting measurements. Our data demonstrate that RLIPC reduced cerebral I/R injury, decreased the volume of the MCAO-evoked infarct region, decreased serum levels of LDH and CK-MB, and reduced neurological deficits and apoptosis after I/R injury. Moreover, rats receiving RLIPC showed increased cortical AKT phosphorylation, but protein phosphorylation level was unchanged in the survivor activating factor enhancement (SAFE) signalling pathway. Accordingly, inhibition of AKT with wortmannin abolished the neuroprotective action of liver preconditioning. Our study showed for the first time that liver ischaemic preconditioning effectively protects brain against cerebral I/R injury by activating an AKT-dependent pathway.

Compromised Dynamic Cerebral Autoregulation in Patients With Idiopathic Rapid Eye Movement Behavior Disorder: A Case-Control Study Using Transcranial Doppler

BACKGROUND

Patients with idiopathic rapid eye movement behavior disorder (IRBD) have been suggested to exhibit altered cerebral perfusion and abnormal cerebral blood flow, which imply a possibility of cerebral autoregulation (CA) impairment. We aimed to investigate the dynamic CA (dCA) in patients with IRBD during wakefulness and to explore the correlations between dCA parameters and clinical measurements.

METHODS

We assessed the dCA capability of 30 patients with IRBD and 36 sex- and age-matched healthy controls by using transcranial Doppler and finger plethysmography. CA function was evaluated by transfer function analysis based on spontaneous oscillation of cerebral blood flow and arterial blood pressure. Transfer function parameters (phase difference and gain) were used to quantify the CA.

RESULTS

No significant differences were observed between the right and left middle cerebral artery dCA parameters (phase difference and gain) of both groups. Patients with IRBD had significantly lower phase difference than the healthy controls, indicating their impaired CA capability. Besides, the value of gain in patients with IRBD was higher than the healthy controls, but the difference did not reach statistical level.

CONCLUSIONS

CA function is compromised in patients with IRBD during wakefulness, which might be an intermediate link between IRBD and neurological symptoms.