RECAST (Remote Ischemic Conditioning After Stroke Trial): A Pilot Randomized Placebo Controlled Phase II Trial in Acute Ischemic Stroke

Baseline systolic blood pressure, hypertension history, and efficacy of remote ischemic conditioning

OBJECTIVE

We performed a post hoc exploratory analysis of Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke (RICAMIS) to determine whether hypertension history and baseline systolic blood pressure (SBP) affect the efficacy of remote ischemic conditioning (RIC).

METHODS

Based on the full analysis set of RICAMIS, patients were divided into hypertension versus non-hypertension group, or <140 mmHg versus ≥140 mmHg group. Each group was further subdivided into RIC and control subgroups. The primary outcome was modified Rankin Scale (mRS) 0-1 at 90 days. Efficacy of RIC was compared among patients with hypertension versus nonhypertension history and SBP of <140 mmHg versus ≥140 mmHg. Furthermore, the interaction effect of treatment with hypertension and SBP was assessed.

RESULTS

Compared with control group, RIC produced a significantly higher proportion of patients with excellent functional outcome in the nonhypertension group (RIC vs. control: 65.7% vs. 57.0%, OR 1.45, 95% CI 1.06-1.98; p = 0.02), but no significant difference was observed in the hypertension group (RIC vs. control: 69.1% vs. 65.2%, p = 0.17). Similar results were observed in SBP ≥140 mmHg group (RIC vs. control: 68.0% vs. 61.2%, p = 0.009) and SBP <140 mmHg group (RIC vs. control: 65.6% vs. 64.7%, p = 0.77). No interaction effect of RIC on primary outcome was identified.

INTERPRETATION

Hypertension and baseline SBP did not affect the neuroprotective effect of RIC, but they were associated with higher probability of excellent functional outcome in patients with acute moderate ischemic stroke who received RIC treatment.

Impact of remote ischemic postconditioning on acute ischemic stroke in China: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Acute ischemic stroke (AIS) is a significant health burden in China, affecting a sizable portion of the population. Conventional pharmacological treatments frequently fall short of desirable outcomes. Therefore, exploring alternative therapies is crucial. Remote ischemic postconditioning (RIPostC) is a noninvasive and cost-effective adjunctive therapy. This study aimed to investigate the efficacy and safety of RIPostC as an adjunctive therapy for AIS to inform clinical practice.

METHODS

A comprehensive search was conducted across the PubMed, Embase, Web of Science, China National Knowledge Infrastructure (CNKI), WanFang, Weipu (VIP), and China Biology Medicine disc (CBM) databases up to October 2023. All included studies underwent bias risk assessment using the Cochrane risk-of-bias assessment tool. The primary outcome measure was the National Institute of Health Stroke Scale (NIHSS), with secondary outcomes including the Barthel index (BI), D-dimer, C-reactive protein (CRP), fibrinogen (FIB), brain-derived neurotrophic factor (BDNF), modified Rankin scale (mRS), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. The data were analyzed using fixed-effects and random-effects models in Review Manager, with mean differences (MDs) and 95% confidence intervals (CIs) calculated for each outcome. The grading of recommendations, assessment, development, and evaluations (GRADE) approach was used to evaluate the level of evidence for each outcome measure.

RESULTS

This meta-analysis included 38 studies, encompassing 4334 patients. Compared with the control group, the RIPostC group had significantly lower NIHSS scores, serum CRP, D-dimer, IL-6, TNF-α, and FIB levels, and increased BDNF levels. Moreover, it improved the patient's BI and mRS scores. According to the GRADE approach, the quality of evidence for mRS was deemed "moderate," while the NIHSS, BI, and CRP were rated as "low" quality. IL-6, TNF-α, FIB, D-dimer, and BDNF received "very low" quality ratings.

CONCLUSION

The findings suggest that RIPostC activates endogenous protective mechanisms, providing benefits to patients with AIS.

Remote Ischemic Conditioning in Stroke Recovery

Remote ischemic conditioning (RIC) is a therapeutic strategy to protect a vital organ like the brain from ischemic injury through brief and repeat cycles of ischemia and reperfusion in remote body parts such as arm or leg. RIC has been applied in different aspects of the stroke field and has shown promise. This narrative review will provide an overview of how to implement RIC in stroke patients, summarize the clinical evidence of RIC on stroke recovery, and discuss unresolved questions and future study directions.

Obesity-induced Ly6CHigh and Ly6CLow monocyte subset changes abolish post-ischemic limb conditioning benefits in stroke recovery

Remote limb conditioning (RLC), performed by intermittent interruption of blood flow to a limb, triggers endogenous tolerance mechanisms and improves stroke outcomes. The underlying mechanism for the protective effect involves a shift of circulating monocytes to a Ly6CHigh proinflammatory subset in normal metabolic conditions. The current study investigates the effect of RLC on stroke outcomes in subjects with obesity, a vascular comorbidity. Compared to lean mice, obese stroke mice displayed significantly higher circulating monocytes (monocytosis), increased CD45High monocytes/macrophages infiltration to the injured brain, worse acute outcomes, and delayed recovery. Unlike lean mice, obese mice with RLC at 2 hours post-stroke failed to shift circulating monocytes to pro-inflammatory status and nullified RLC-induced functional benefit. The absence of the monocyte shift was also observed in splenocytes incubated with RLC serum from obese mice, while the shift was observed in the cultures with RLC serum from lean mice. These results showed that the alteration of monocytosis and subsets underlies negating RLC benefits in obese mice and suggest careful considerations of comorbidities at the time of RLC application for stroke therapy.

Remote Ischemic Conditioning With Medical Management or Reperfusion Therapy for Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND AND OBJECTIVES

Remote ischemic conditioning (RIC) is a low-cost, accessible, and noninvasive neuroprotective treatment strategy, but its efficacy and safety in acute ischemic stroke are controversial. With the publication of several randomized controlled trials (RCTs) and the recent results of the RESIST trial, it may be possible to identify the patient population that may (or may not) benefit from RIC. This systematic review and meta-analysis aims to evaluate the effectiveness and safety of RIC in patients with ischemic stroke receiving different treatments by pooling data of all randomized controlled studies to date.

METHODS

We searched the PubMed, Embase, Cochrane, Elsevier, and Web of Science databases to obtain articles in all languages from inception until May 25, 2023. The primary outcome was the modified Rankin Scale (mRS) score at the specified endpoint time in the trial. The secondary outcomes were change in NIH Stroke Scale (NIHSS) and recurrence of stroke events. The safety outcomes were cardiovascular events, cerebral hemorrhage, and mortality. The quality of articles was evaluated through the Cochrane risk assessment tool. This study was registered in PROSPERO (CRD42023430073).

RESULTS

There were 7,657 patients from 22 RCTs included. Compared with the control group, patients who received RIC did not have improved mRS functional outcomes, regardless of whether they received medical management, reperfusion therapy with intravenous thrombolysis (IVT), or mechanical thrombectomy (MT). In the medical management group, patients who received RIC had decreased incidence of stroke recurrence (risk ratio 0.63, 95% CI 0.43-0.92, p = 0.02) and lower follow-up NIHSS score by 1.72 points compared with the control group (p < 0.00001). There was no increased risk of adverse events including death or cerebral hemorrhage in the IVT or medical management group.

DISCUSSION

In patients with ischemic stroke who are not eligible for reperfusion therapy, RIC did not affect mRS functional outcomes but significantly improved the NIHSS score at the follow-up endpoint and reduced stroke recurrence, without increasing the risk of cerebral hemorrhage or death. In patients who received IVT or MT, the benefit of RIC was not observed.

Duration of Remote Ischemic Conditioning and Outcome in Acute Ischemic Stroke

BACKGROUND

Remote ischemic conditioning has been found to be effective in improving functional outcomes in acute ischemic stroke. We conducted a post hoc analysis of the RICAMIS (Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke) trial to determine whether long-term remote ischemic conditioning duration after stroke onset is associated with better clinical outcomes in ischemic stroke.

METHODS AND RESULTS

Patients from the full analysis set were included in this secondary analysis. The primary outcome was the proportion of patients with an excellent functional outcome at 90 days, defined as a modified Rankin Scale score of 0 to 1. Among the 1776 patients, there were 55 patients in the 1 to 7 days remote ischemic conditioning group, 345 in the 8 to 10 days group, 412 in the 11 to 13 days group, 51 in the 14 to 16 days group, and 913 in the control group. Compared with the control group, a significantly higher proportion of excellent functional outcomes at 90 days was found in the 11 to 13 days remote ischemic conditioning group (adjusted absolute difference, 9.1% [95% CI, 3.7%-14.5%]; P =0.001), which was attenuated in the other groups (adjusted absolute difference in the 8-10 days group, 2.0% [95% CI, -4.0% to 8.0%]; P=0.51; adjusted absolute difference in the 14-16 days group, 7.4% [95% CI, -5.8% to 20.5%]; P=0.27), but compared to the control group, there was lower proportion of excellent functional outcomes in the 1 to 7 days group (adjusted absolute difference, -14.4% [95% CI, -27.8% to 0.0%]; P=0.05).

CONCLUSIONS

Among patients with acute moderate ischemic stroke, a higher likelihood of excellent clinical outcome was found in patients with longer duration of remote ischemic conditioning.

Effect of Remote Ischemic Conditioning in Ischemic Stroke Subtypes: A Post Hoc Subgroup Analysis From the RESIST Trial

BACKGROUND

Remote ischemic conditioning (RIC) is a simple and noninvasive procedure that has proved to be safe and feasible in numerous smaller clinical trials. Mixed results have been found in recent large randomized controlled trials. This is a post hoc subgroup analysis of the RESIST trial (Remote Ischemic Conditioning in Patients With Acute Stroke), investigating the effect of RIC in different acute ischemic stroke etiologies, and whether an effect was modified by treatment adherence.

METHODS

Eligible patients were adults (aged ≥18 years), independent in activities of daily living, who had prehospital stroke symptoms with a duration of less than 4 hours. They were randomized to RIC or sham. The RIC treatment protocol consisted of 5 cycles with 5 minutes of cuff inflation alternating with 5 minutes with a deflated cuff. Acceptable treatment adherence was defined as when at least 80% of planned RIC cycles were received. The analysis was performed using the entire range (shift analysis) of the modified Rankin Scale (ordinal logistic regression).

RESULTS

A total of 698 had acute ischemic stroke, 253 (36%) were women, and the median (interquartile range) age was 73 (63-80) years. Median (interquartile range) overall adherence to RIC/sham was 91% (68%-100%). In patients with a stroke due to cerebral small vessel disease, who were adherent to treatment, RIC was associated with improved functional outcome, and the odds ratio for a shift to a lower score on the modified Rankin Scale was 2.54 (1.03-6.25); P=0.042. The association remained significant after adjusting for potential confounders. No significant associations were found with other stroke etiologies, and the overall test for interaction was not statistically significant (χ2, 4.33, P=0.23).

CONCLUSIONS

In patients with acute ischemic stroke due to cerebral small vessel disease, who maintained good treatment adherence, RIC was associated with improved functional outcomes at 90 days. These results should only serve as a hypothesis-generating for future trials.

REGISTRATION

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

Remote ischemic conditioning after stroke: Research progress in clinical study

BACKGROUND AND PURPOSE

Stroke is a leading cause of global morbidity and mortality, indicating the necessity and urgency of effective prevention and treatment. Remote ischemic conditioning (RIC) is a convenient, simple, non-intrusive, and effective method that can be easily added to the treatment regime of stroke patients. Animal experiments and clinical trials have proved the neuroprotective effects of RIC on brain injury including (examples of neuroprotective effects). This neuroprotection is achieved by raising brain tolerance to ischemia, increasing local cerebral blood perfusion, promoting collateral circulations, neural regeneration, and reducing the incidence of hematomas in brain tissue. This current paper will summarize the studies within the last 2 years for the comprehensive understanding of the use of RIC in the treatment of stroke.

METHODS

This paper summarizes the clinical research progress of RIC on stroke (ischemic stroke and hemorrhagic stroke (HS)). This paper is a systematic review of research published on registered clinical trials using RIC in stroke from inception through November 2022. Four major databases (PUBMED, WEB OF SCIENCE, EMBASE, and ClinicalTrials.gov) were searched.

RESULTS

Forty-eight studies were identified meeting our criteria. Of these studies, 14 were in patients with acute ischemic stroke with onset times ranging from 6 h to 14 days, seven were in patients with intravenous thrombolysis or endovascular thrombectomy, 10 were in patients with intracranial atherosclerotic stenosis, six on patients with vascular cognitive impairment, three on patients with moyamoya disease, and eight on patients with HS. Of the 48 studies, 42 were completed and six are ongoing.

CONCLUSIONS

RIC is safe, feasible, and effective in the treatment of stroke. Large-scale research is still required to explore the optimal treatment options and mechanisms of RIC in the future to develop a breakthrough in stroke prevention and treatment.

A Non-Coronary, Peripheral Arterial Atherosclerotic Disease (Carotid, Renal, Lower Limb) in Elderly Patients-A Review: Part I-Epidemiology, Risk Factors, and Atherosclerosis-Related Diversities in Elderly Patients

Atherosclerosis is a generalized and progressive disease. Ageing is a key risk factor for atherosclerosis progression that is associated with the increased incidence of ischemic events in supplied organs, including stroke, coronary events, limb ischemia, or renal failure. Cardiovascular disease is the leading cause of death and major disability in adults ≥ 75 years of age. Atherosclerotic occlusive disease affects everyday activity and quality of life, and it is associated with reduced life expectancy. Although there is evidence on coronary artery disease management in the elderly, there is insufficient data on the management in older patients presented with atherosclerotic lesions outside the coronary territory. Despite this, trials and observational studies systematically exclude older patients, particularly those with severe comorbidities, physical or cognitive dysfunctions, frailty, or residence in a nursing home. This results in serious critical gaps in knowledge and a lack of guidance on the appropriate medical treatment and referral for endovascular or surgical interventions. Therefore, we attempted to gather data on the prevalence, risk factors, and management strategies in patients with extra-coronary atherosclerotic lesions.

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.

Age and efficacy of remote ischemic conditioning in acute ischemic stroke

AIMS

A post hoc analysis of RICAMIS trial to evaluate functional outcomes in relation to patient age.

METHODS

Patients in RICAMIS were divided into six age groups. The primary outcome was excellent functional outcome at 90 days, defined as modified Rankin Scale (mRS) score of 0-1. Compared with patients receiving usual care alone, we investigated the association of remote ischemic conditioning (RIC) effect with functional outcomes in each group and the interaction between RIC effect and age.

RESULTS

Of 1776 patients, 498 were assigned to <60 years, 326 to 60 to <65 years, 325 to 65 to <70 years, 278 to 70 to <75 years, 206 to 75 to <80 years, and 143 to ≥80 years. Higher proportions of primary outcome were found associated with RIC in <60 years group (72.6% vs. 64.8%; adjusted risk difference [RD], 6.8%; 95% CI, -1.6% to 15.1%; p = 0.11), 60 to <65 years group (70.7% vs. 67.1%; adjusted RD, 3.1%; 95% CI, -7.2% to 13.3%; p = 0.56), 65 to <70 years group (70.5% vs. 63.6%; adjusted RD, 3.5%; 95% CI, -6.8% to 13.8%; p = 0.51), 70 to <75 years group (59.7% vs. 54.9%; adjusted RD, 4.7%; 95% CI, -7.1% to 16.4%; p = 0.61), 75 to <80 years group (61.5% vs. 55.9%; adjusted RD, 5.7%; 95% CI, -7.8% to 19.1%; p = 0.41), and ≥ 80 years group (59.2% vs. 59.7%; adjusted RD, -2.6%; 95% CI, -18.8% to 13.5%; p = 0.75). No significant interaction between RIC effect and age was found among groups.

CONCLUSIONS

This is the first report that RIC effect may be attenuated with increasing age in patients with acute moderate ischemic stroke with respect to functional outcome.

Remote Ischemic Conditioning Enhances Collateral Circulation Through Leptomeningeal Anastomosis and Diminishes Early Ischemic Lesions and Infarct Volume in Middle Cerebral Artery Occlusion

Remote ischemic conditioning (RIC) has attracted much attention as a protective strategy for the heart and brain, although the underlying mechanisms remain unclear. We hypothesized that RIC enhances collateral circulation during cerebral ischemia through endothelial function and mitigates both early ischemic change and final infarct volume. We tested the RIC and sham procedure 30 min after permanent middle cerebral artery occlusion (MCAO) in male mice. Collateral circulation was examined during the procedure with 2D color-coded ultrasound imaging. Immediately after four cycles of RIC, early ischemic lesions on magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), and development of pial collateral vessels were examined. The neurological signs and infarct volume with TTC were examined until 48 h after daily RIC. As compared with sham procedure, RIC enhanced collateral circulation, diminished early ischemic lesions, enlarged pial collaterals, and mitigated infarct volume. Next, we examined the effect of inhibitor of nitric oxide synthase (NOS) and Akt on the beneficial effect of RIC in MCAO. Both allosteric Akt inhibitor, 8-[4-(1-Aminocyclobutyl)phenyl]-9-phenyl[1,2,4]triazolo[3,4-f][1,6]naphthyridin-3(2H)-one (MK2206), and two NOS inhibitors, N5-(1-Iminoethyl)-L-ornithine dihydrochloride (L-NIO) and NG-Nitro-L-arginine methyl ester hydrochloride (L-NAME), counteracted the beneficial effect of RIC on collateral circulation, early lesions, pial anastomosis, and infarct volume. In permanent MCAO, RIC could enhance collateral circulation through leptomeningeal anastomosis with Akt-eNOS pathway and diminish early lesion and final infarct volume.

Randomized feasibility trial of remote ischemic conditioning to enhance resuscitation (RICE)

RATIONALE

Restoration of blood flow after out-of-hospital cardiac arrest (OHCA) is associated with inflammation that causes cellular injury. The extent of this reperfusion injury (RI) is associated with the duration of ischemia and adequacy of resuscitation. Remote ischemic conditioning (RIC) consists of repeated application of non-lethal ischemia then reperfusion to a limb distal to the heart by inflating a blood pressure (BP) cuff. Trials in animal models in cardiac arrest and in humans with acute infarction show RIC reduces RI.

OBJECTIVE

We sought to demonstrate the feasibility and safety of RIC in patients resuscitated from OHCA and transported to hospital.

METHODS

This study was conducted under exception from informed consent (EFIC) for emergency research. Eligible subjects were randomized with masked allocation to control (standard care) versus intervention (standard care and RIC). Included were adults with non-traumatic OHCA. The primary outcome was attrition, the proportion of patients enrolled and not on allocated therapy for the study duration. Key secondary outcomes were survival to discharge, neurologic status at discharge, hospital-free survival, and adverse events. Results were summarized descriptively as recommended for pilot studies.

RESULTS

N = 30 patients were enrolled (n = 14 control, n = 16 intervention). Mean age of enrolled patients was 52.5 ± 16.2 years. Eight (27%) were female gender and 7 (23%) had a shockable first recorded rhythm. 100% of enrolled patients completed their allocated study intervention (i.e., 0% attrition). The RIC group had 7 (44%) survival to discharge and median Rankin score of 6 (IQR 1, 6) at discharge as compared to the standard care group which had 6 (43%) survival to discharge and median Rankin score of 6 (IQR 1.5, 6) at discharge. A single patient (6%) in the intervention group had transient occlusion of their upper extremity intravenous line, which immediately resolved on repositioning of the blood pressure cuff.

CONCLUSION

Application of RIC to patients resuscitated from CA and transported to an ED is feasible and safe. An adequately powered trial is required to assess whether RIC is effective at decreasing morbidity and mortality after CA.

Baseline neurologic deficit and efficacy of remote ischemic conditioning after acute ischemic stroke: A post hoc analysis of RICAMIS

RICAMIS (ClinicalTrials.gov Identifier: NCT03740971) trial has demonstrated efficacy of remote ischemic conditioning (RIC) in acute ischemic stroke, but whether baseline NIHSS score can affect outcomes in stroke remains unclear. We conducted a post hoc analysis of RICAMIS to investigate the issue. Patients included in RICAMIS were divided into three groups based on baseline NIHSS score. The primary outcome was excellent functional outcome at 90 days, defined as mRS score of 0-1. Compared with patients receiving usual care, we investigated association of RIC effect with outcomes in each group and interaction between RIC effect and stroke severity. Among 1776 patients, 1255 were assigned into NIHSS score 6-8 group, 402 into NIHSS score 9-12 group, and 119 into NIHSS score 13-16 group. A higher proportion of primary outcome was found associated with RIC in NIHSS score 9-12 group (adjusted risk difference [RD], 14.6 ​%; 95 ​% CI, 5.0 ​%-24.2 ​%; P ​= ​0.003), but no significant association was found in NIHSS score 6-8 group (adjusted RD, 2.3 ​%; 95 ​% CI, -2.5 ​%-7.2 ​%; P ​= ​0.34), or in NIHSS score 13-16 group (adjusted RD, 9.7 ​%; 95 ​% CI, -7.5 ​%-26.9 ​%; P ​= ​0.27). There was a significant interaction between RIC effect and stroke severity when analysis was performed between NIHSS score 6-8 and 9-12 groups (P ​= ​0.04), but not between NIHSS score 9-12 and 13-16 groups (P ​= ​0.57). Current study firstly reported patients with NIHSS score 9-12 may get more benefit from RIC after stroke with respect to excellent functional outcome at 90 days.

Remote Ischemic Conditioning and Outcomes in Acute Ischemic Stroke With Versus Without Large Artery Atherosclerosis

BACKGROUND

RICAMIS trial (The Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke) has demonstrated efficacy of remote ischemic conditioning (RIC) in acute ischemic stroke. We conducted a post hoc analysis of RICAMIS to investigate whether large artery atherosclerosis (LAA) subtype contributed to the outcomes.

METHODS

This is a post hoc analysis of the RICAMIS trial. Patients randomized to RIC group and Control group in full analysis set of RICAMIS were classified into LAA and non-LAA subtypes. The primary outcome was excellent functional outcome at 90 days, defined as modified Rankin Scale score of 0 to 1. Compared with patients receiving usual care, we investigated the association of RIC effect with outcomes in stroke subtypes and the interaction between RIC effect and stroke subtypes. The primary analysis was adjusted analysis.

RESULTS

Among 1773 patients, 516 were assigned to LAA subtype (229 in the RIC group and 287 in the control group) and 1257 to non-LAA subtype (633 in the RIC group and 624 in the control group). Median age was 65 years, and 34.2% were women. A higher proportion of primary outcome was found to be associated with RIC treatment in LAA subtype (adjusted risk difference, 11.4% [95% CI, 3.6%-19.2%]; P=0.004), but not in non-LAA subtype (adjusted risk difference, 4.1% [95% CI, -1.1% to 9.3%]; P=0.12). There was no significant interaction between RIC effect and stroke subtypes (P=0.12).

CONCLUSIONS

Patients with LAA subtype may benefit from RIC after stroke with respect to excellent functional outcome at 90 days.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03740971.

Remote Ischemic conditioning as an emerging tool to improve corticospinal transmission in individuals with chronic spinal cord injury

PURPOSE OF REVIEW

Remote ischemic conditioning (RIC) involves transient blood flow restriction to one limb leading to systemic tissue-protective effects. RIC shares some potential underlying mechanisms with intermittent hypoxia (IH), in which brief bouts of systemic hypoxia trigger increases in growth factor expression and neural plasticity. RIC has shown promise in acute myocardial infarction and stroke but may be applicable toward chronic neuropathology as well. Consequently, this review discusses similarities and differences between RIC and IH and presents preliminary and ongoing research findings regarding RIC.

RECENT FINDINGS

Several publications demonstrated that combining RIC with motor training may enhance motor learning in adults with intact nervous systems, though the precise mechanisms were unclear. Our own preliminary data has found that RIC, in conjunction with task specific exercise, can increase corticospinal excitability in a subset of people without neurological injury and in those with chronic cervical spinal cord injury or amyotrophic lateral sclerosis.

SUMMARY

RIC is a low-cost intervention easy to deliver in a clinical or home setting. Its potential application to facilitate neural plasticity and motor learning during rehabilitation training for individuals with chronic neurological disorders is a novel concept requiring further investigation to characterize mechanisms, safety, and efficacy.

Evolving Clinical-Translational Investigations of Cerebroprotection in Ischemic Stroke

Ischemic stroke is a highly morbid disease, with over 50% of large vessel stroke (middle cerebral artery or internal carotid artery terminus occlusion) patients suffering disability despite maximal acute reperfusion therapy with thrombolysis and thrombectomy. The discovery of the ischemic penumbra in the 1980s laid the foundation for a salvageable territory in ischemic stroke. Since then, the concept of neuroprotection has been a focus of post-stroke care to (1) minimize the conversion from penumbra to core irreversible infarct, (2) limit secondary damage from ischemia-reperfusion injury, inflammation, and excitotoxicity and (3) to encourage tissue repair. However, despite multiple studies, the preclinical-clinical research enterprise has not yet created an agent that mitigates post-stroke outcomes beyond thrombolysis and mechanical clot retrieval. These translational gaps have not deterred the scientific community as agents are under continuous investigation. The NIH has recently promoted the concept of cerebroprotection to consider the whole brain post-stroke rather than just the neurons. This review will briefly outline the translational science of past, current, and emerging breakthroughs in cerebroprotection and use of these foundational ideas to develop a novel paradigm for optimizing stroke outcomes.

Remote Ischemic Conditioning for Acute Stroke: The RESIST Randomized Clinical Trial

Importance

Despite some promising preclinical and clinical data, it remains uncertain whether remote ischemic conditioning (RIC) with transient cycles of limb ischemia and reperfusion is an effective treatment for acute stroke.

Objective

To evaluate the effect of RIC when initiated in the prehospital setting and continued in the hospital on functional outcome in patients with acute stroke.

Design, Setting, and Participants

This was a randomized clinical trial conducted at 4 stroke centers in Denmark that included 1500 patients with prehospital stroke symptoms for less than 4 hours (enrolled March 16, 2018, to November 11, 2022; final follow-up, February 3, 2023).

Intervention

The intervention was delivered using an inflatable cuff on 1 upper extremity (RIC cuff pressure, ≤200 mm Hg [n = 749] and sham cuff pressure, 20 mm Hg [n = 751]). Each treatment application consisted of 5 cycles of 5 minutes of cuff inflation followed by 5 minutes of cuff deflation. Treatment was started in the ambulance and repeated at least once in the hospital and then twice daily for 7 days among a subset of participants.

Main Outcomes and Measures

The primary end point was improvement in functional outcome measured as a shift across the modified Rankin Scale (mRS) score (range, 0 [no symptoms] to 6 [death]) at 90 days in the target population with a final diagnosis of ischemic or hemorrhagic stroke.

Results

Among 1500 patients who were randomized (median age, 71 years; 591 women [41%]), 1433 (96%) completed the trial. Of these, 149 patients (10%) were diagnosed with transient ischemic attack and 382 (27%) with a stroke mimic. In the remaining 902 patients with a target diagnosis of stroke (737 [82%] with ischemic stroke and 165 [18%] with intracerebral hemorrhage), 436 underwent RIC and 466 sham treatment. The median mRS score at 90 days was 2 (IQR, 1-3) in the RIC group and 1 (IQR, 1-3) in the sham group. RIC treatment was not significantly associated with improved functional outcome at 90 days (odds ratio [OR], 0.95; 95% CI, 0.75 to 1.20, P = .67; absolute difference in median mRS score, -1; -1.7 to -0.25). In all randomized patients, there were no significant differences in the number of serious adverse events: 169 patients (23.7%) in the RIC group with 1 or more serious adverse events vs 175 patients (24.3%) in the sham group (OR, 0.97; 95% CI, 0.85 to 1.11; P = .68). Upper extremity pain during treatment and/or skin petechia occurred in 54 (7.2%) in the RIC group and 11 (1.5%) in the sham group.

Conclusions and Relevance

RIC initiated in the prehospital setting and continued in the hospital did not significantly improve functional outcome at 90 days in patients with acute stroke.

Trial Registration

ClinicalTrials.gov Identifier: NCT03481777.

Exosome is involved in liver graft protection after remote ischemia reperfusion conditioning

BACKGROUND

Remote ischemic perconditioning (RIPerC) has been demonstrated to protect grafts from hepatic ischemia-reperfusion injury (IRI). This study investigated the role of exosomes in RIPerC of liver grafts in rats.

METHODS

Twenty-five rats (including 10 donors) were randomly divided into five groups (n = 5 each group): five rats were used as sham-operated controls (Sham), ten rats were for orthotopic liver transplantation (OLT, 5 donors and 5 recipients) and ten rats were for OLT + RIPerC (5 donors and 5 recipients). Liver architecture and function were evaluated.

RESULTS

Compared to the OLT group, the OLT + RIPerC group exhibited significantly improved liver graft histopathology and liver function (P < 0.05). Furthermore, the number of exosomes and the level of P-Akt were increased in the OLT + RIPerC group.

CONCLUSIONS

RIPerC effectively improves graft architecture and function, and this protective effect may be related to the increased number of exosomes. The upregulation of P-Akt may be involved in underlying mechanisms.

Time from Onset to Remote Ischemic Conditioning and Clinical Outcome After Acute Moderate Ischemic Stroke

OBJECTIVE

We conducted a post hoc exploratory analysis of Remote Ischemic Conditioning for Acute Moderate Ischemic Stroke (RICAMIS) to determine whether early remote ischemic conditioning (RIC) initiation after stroke onset was associated with clinical outcome in patients with acute moderate ischemic stroke.

METHODS

In RICAMIS, patients receiving RIC treatment in the intention-to-treat analysis were divided into 2 groups based on onset-to-treatment time (OTT): early RIC group (OTT ≤ 24 hours) and late RIC group (OTT 24-48 hours). Patients receiving usual care without RIC treatment from intention-to-treat analysis were assigned as the control group. The primary outcome was excellent functional outcome at 90 days.

RESULTS

Among 1,776 patients from intention-to-treat analysis, 387 were in the early RIC group, 476 in the late RIC group, and 913 in the control group. In the post hoc exploratory analysis, a higher proportion of excellent functional outcome was found in the early RIC versus control group (adjusted absolute difference = 8.1%, 95% confidence interval [CI] = 2.5%-13.8%, p = 0.005), but no difference in outcomes was detected in the late RIC versus control group (adjusted absolute difference = 3.3%, 95% CI = -2.1% to 8.6%, p = 0.23), or in the early RIC versus late RIC group (adjusted absolute difference = 5.0%, 95% CI = -1.3% to 11.2%, p = 0.12). Similar results were found in the per-protocol analysis.

INTERPRETATION

Among patients with acute moderate ischemic stroke who are not candidates for intravenous thrombolysis or endovascular therapy, early RIC initiation within 24 hours of onset may be associated with higher likelihood of excellent clinical outcome. ANN NEUROL 2023;94:561-571.

Autonomic function may mediate the neuroprotection of remote ischemic postconditioning in stroke: A randomized controlled trial

OBJECTIVES

To evaluate the effect of remote ischemic postconditioning (RIPostC) on the prognosis of acute ischemic stroke(AIS) patients and investigate the mediating role of autonomic function in the neuroprotection of RIPostC.

MATERIALS AND METHODS

132 AIS patients were randomized into two groups. Patients received four cycles of 5-min inflation to a pressure of 200 mmHg(i.e., RIPostC) or patients' diastolic BP(i.e., shame), followed by 5 min of deflation on healthy upper limbs once a day for 30 days. The main outcome was neurological outcome including the National Institutes of Health Stroke Scale (NIHSS), modified Rankin Scale (mRS), and Barthel index(BI). The second outcome measure was autonomic function measured by heart rate variability(HRV).

RESULTS

Compared with the baseline, the post-intervention NIHSS score was significantly reduced in both groups (P<0.001). NIHSS score was significantly lower in the control group than intervention group at day 7.[RIPostC:3(1,5) versus shame:2(1,4); P=0.030]. mRS scored lower in the intervention group compared with the control group at day 90 follow-up(RIPostC:0.5±2.0 versus shame:1.0±2.0;P=0.016). The goodness-of-fit test revealed a significant difference between the generalized estimating equation model of mRS and BI scores of uncontrolled-HRV and controlled-HRV(P<0.05, both). The results of bootstrap revealed a complete mediation effect of HRV between group on mRS[indirect effect: -0.267 (LLCI = -0.549, ULCI = -0.048), the direct effect: -0.443 (LLCI = -0.831, ULCI = 0.118)].

CONCLUSION

This is the first human-based study providing evidence for a mediation role of autonomic function between RIpostC and prognosis in AIS patients. It indicated that RIPostC could improve the neurological outcome of AIS patients. Autonomic function may play a mediating role in this association.

TRIAL REGISTRATION

The clinical trials registration number for this study is NCT02777099 (ClinicalTrials.gov Identifier).

Remote ischemic conditioning in the treatment of acute cerebral infarction: A case control study

Objective

This paired case-control study aimed to evaluate the efficacy and safety of remote ischemic conditioning (RIC) in patients with acute cerebral infarction (CI) and explore potential serological markers of RIC.

Methods

Patients with acute CI (<72 h) were matched 1:1 according to age, sex, and CI conditions and were divided into the RIC group and the control group. The RIC group received RIC intervention for 7 days on top of routine treatment, while the control group received a sham RIC. The curative effects and adverse reactions were observed.

Result

A total of 66 patients (mean age 60.00 ± 11.37 years; mean time of acute CI onset 32.91 ± 17.94 h) completed the study. The National Institute of Health stroke scale score on day 7, modified Rankin Scale scores on day 7 and day 90 were significantly lower than the baseline in the RIC group (P < 0.001, P = 0.003, P = 0.004, respectively) but not in the control group (P = 0.056, P = 0.169, P = 0.058, respectively). RIC was well-tolerated, and no adverse events were reported. Both plasma hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor increased in the RIC group from day 0 to day 7, while they decreased in the control group. The changes in plasma HIF-1α in the RIC group were statistically different from those in the control group (P = 0.006).

Conclusion

Early and short-term RIC treatment was well-tolerated and effective in improving the prognosis in acute CI. HIF-1α can be recognized as a biomarker for evaluating the efficacy of RIC treatment.

Efficacy and safety of remote ischemic conditioning for acute ischemic stroke: A comprehensive meta-analysis from randomized controlled trials

BACKGROUND AND PURPOSE

Remote ischemic conditioning (RIC) is a remote, transient, and noninvasive procedure providing temporary ischemia and reperfusion. However, there is no comprehensive literature investigating the efficacy and safety of RIC for the treatment of acute ischemic stroke. In the present study, we performed a comprehensive meta-analysis of the available studies.

METHODS

MEDLINE, Embase, the Cochrane Library database (CENTRAL), and ClinicalTrials.gov were searched before Sep 7, 2022. The data were analyzed using Review Manager 5.4.1 software, Stata version 16.0 software, and R 4.2.0 software. Odds ratio (OR), mean difference (MD), and corresponding 95% CIs were pooled using fixed-effects meta-analysis.

RESULTS

We pooled 6392 patients from 17 randomized controlled trials. Chronic RIC could reduce the recurrence of ischemic stroke at the endpoints (OR 0.67, 95% CI [0.51, 0.87]). RIC could also improve the prognosis of patients at 90 days as assessed by mRS score (mRS 0-1: OR 1.29, 95% CI [1.09, 1.52]; mRS 0-2: OR 1.22, 95% CI [1.01, 1.48]) and at the endpoints assessed by NIHSS score (MD -0.99, 95% CI [-1.45, -0.53]). RIC would not cause additional adverse events such as death (p = 0.72), intracerebral hemorrhage events (p = 0.69), pneumonia (p = 0.75), and TIA (p = 0.24) but would inevitably cause RIC-related adverse events (OR 26.79, 95% CI [12.08, 59.38]).

CONCLUSIONS

RIC could reduce the stroke recurrence and improve patients' prognosis. Intervention on bilateral upper limbs, 5 cycles, and a length of 50 min in each intervention might be an optimal protocol for RIC at present. RIC could be an effective therapy for patients not eligible for reperfusion therapy. RIC would not cause other adverse events except for relatively benign RIC-related adverse events.

Endovascular treatment over 24 hours after ischemic stroke onset: a single-center retrospective study

PURPOSE

The aim of this study is to evaluate the safety and effectiveness of endovascular treatment (EVT) for acute ischemic stroke caused by large-vessel obstruction or stenosis (AIS-LVO/S) over 24 h after first AIS symptom recognition (FAISSR).

METHODS

A total of 33 AIS-LVO/S cases with EVT over 24 h after FAISSR during the period from January 2019 to February 2022 in our hospital were divided into the 90d mRS ≤ 2 group [favorable outcome (FO) group] and 90d mRS > 2 group [unfavorable outcome (UFO) group] and retrospectively analyzed.

RESULTS

The reperfusion was successfully established with EVT in 97% (32/33) of cases, and most (63.6%, 21/33) had 90d mRS ≤ 2 and only 36.4% (12/33) had 90d mRS > 2. Preoperative DWI-ASPECT and ASITN/SIR scores were significantly higher and NIHSS scores were significantly lower in the FO group than those in the UFO group (P < 0.05). In addition, the FAISSR to exacerbation time, FAISSR to groin puncture time, and FAISSR to reperfusion time were significantly longer, and the groin puncture to reperfusion time was significantly shorter in the FO group than those in the UFO group (P < 0.05), but there was no significant difference in the stroke exacerbation to groin puncture time (P > 0.05). The patients with cerebral infarction due to artery dissection had more favorable EVT outcomes, but the patients with posterior cerebral circulation infarction had very poor EVT outcomes.

CONCLUSIONS

The FAISSR to groin puncture time over 24 h may not be a taboo for EVT and it may be safe and effective for AIS-LVO/S in anterior cerebral circulation, especially with lower preoperative NIHSS scores.

The effect of repeated remote ischemic postconditioning after an ischemic stroke (REPOST): A randomized controlled trial

BACKGROUND AND AIMS

A potential strategy to treat ischemic stroke may be the application of repeated remote ischemic postconditioning (rIPostC). This consists of several cycles of brief periods of limb ischemia followed by reperfusion, which can be applied by inflating a simple blood pressure cuff and subsequently could result in neuroprotection after stroke.

METHODS

Adult patients admitted with an ischemic stroke in the past 24 h were randomized 1:1 to repeated rIPostC or sham-conditioning. Repeated rIPostC was performed by inflating a blood pressure cuff around the upper arm (4 × 5 min at 200 mm Hg), which was repeated twice daily during hospitalization with a maximum of 4 days. Primary outcome was infarct size after 4 days or at discharge. Secondary outcomes included the modified Rankin Scale (mRS)-score after 12 weeks and the National Institutes of Health Stroke Scale (NIHSS) at discharge.

RESULTS

The trial was preliminarily stopped after we included 88 of the scheduled 180 patients (average age: 70 years, 68% male) into rIPostC (n = 40) and sham-conditioning (n = 48). Median infarct volume was 2.19 mL in rIPostC group and 5.90 mL in sham-conditioning, which was not significantly different between the two groups (median difference: 3.71; 95% CI: -0.56 to 6.09; p = 0.31). We found no significant shift in the mRS score distribution between groups. The adjusted common odds ratio was 2.09 (95% CI: 0.88-5.00). We found no significant difference in the NIHSS score between groups (median difference: 1.00; 95% CI: -0.99 to 1.40; p = 0.51).

CONCLUSION

This study found no significant improvement in infarct size or clinical outcome in patients with an acute ischemic stroke who were treated with repeated remote ischemic postconditioning. However, due to a lower-than-expected inclusion rate, no definitive conclusions about the effectiveness of rIPostC can be drawn.

Therapeutic Induction of Collateral Flow

Therapeutic induction of collateral flow as a means to salvage tissue and improve outcome from acute ischemic stroke is a promising approach in the era in which endovascular therapy is no longer time-dependent but collateral-dependent. The importance of collateral flow enhancement as a therapeutic for acute ischemic stroke extends beyond those patients with large amounts of salvageable tissue. It also has the potential to extend the time window for reperfusion therapies in patients who are ineligible for endovascular thrombectomy. In addition, collateral enhancement may be an important adjuvant to neuroprotective agents by providing a more robust vascular route for which treatments can gain access to at risk tissue. However, our understanding of collateral hemodynamics, including under comorbid conditions that are highly prevalent in the stroke population, has hindered the efficacy of collateral flow augmentation for improving stroke outcome in the clinical setting. This review will discuss our current understanding of pial collateral function and hemodynamics, including vasoactivity that is critical for enhancing penumbral perfusion. In addition, mechanisms by which collateral flow can be increased during acute ischemic stroke to limit ischemic injury, that may be different depending on the state of the brain and vasculature prior to stroke, will also be reviewed.

Remote ischemic conditioning-induced hyperacute and acute responses of plasma proteome in healthy young male adults: a quantitative proteomic analysis

BACKGROUND

Long-term remote ischemic conditioning (RIC) has been proven to be beneficial in multiple diseases, such as cerebral and cardiovascular diseases. However, the hyperacute and acute effects of a single RIC stimulus are still not clear. Quantitative proteomic analyses of plasma proteins following RIC application have been conducted in preclinical and clinical studies but exhibit high heterogeneity in results due to wide variations in experimental setups and sampling procedures. Hence, this study aimed to explore the immediate effects of RIC on plasma proteome in healthy young adults to exclude confounding factors of disease entity, such as medications and gender.

METHODS

Young healthy male participants were enrolled after a systematic physical examination and 6-month lifestyle observation. Individual RIC sessions included five cycles of alternative ischemia and reperfusion, each lasting for 5 min in bilateral forearms. Blood samples were collected at baseline, 5 min after RIC, and 2 h after RIC, and then samples were processed for proteomic analysis using liquid chromatography-tandem mass spectrometry method.

RESULTS

Proteins related to lipid metabolism (e.g., Apolipoprotein F), coagulation factors (hepatocyte growth factor activator preproprotein), members of complement cascades (mannan-binding lectin serine protease 1 isoform 2 precursor), and inflammatory responses (carboxypeptidase N catalytic chain precursor) were differentially altered at their serum levels following the RIC intervention. The most enriched pathways were protein glycosylation and complement/coagulation cascades.

CONCLUSIONS

One-time RIC stimulus may induce instant cellular responses like anti-inflammation, coagulation, and fibrinolysis balancing, and lipid metabolism regulation which are protective in different perspectives. Protective effects of single RIC in hyperacute and acute phases may be exploited in clinical emergency settings due to apparently beneficial alterations in plasma proteome profile. Furthermore, the beneficial effects of long-term (repeated) RIC interventions in preventing chronic cardiovascular diseases among general populations can also be expected based on our study findings.

Remote ischemic conditioning attenuates blood-brain barrier disruption after recombinant tissue plasminogen activator treatment via reducing PDGF-CC

Treatment of acute ischemic stroke with the recombinant tissue plasminogen activator (rtPA) is associated with increased blood-brain barrier (BBB) disruption and hemorrhagic transformation. Remote ischemic conditioning (RIC) has demonstrated neuroprotective effects against acute ischemic stroke. However, whether and how RIC regulates rtPA-associated BBB disruption remains unclear. Here, a rodent model of thromboembolic stroke followed by rtPA thrombolysis at different time points was performed with or without RIC. Brain infarction, neurological outcomes, BBB permeability, and intracerebral hemorrhage were assessed. The platelet-derived growth factor CC (PDGF-CC)/PDGFRα pathway in the brain tissue, PDGF-CC levels in the skeletal muscle and peripheral blood were also measured. Furthermore, impact of RIC on serum PDGF-CC levels were measured in healthy subjects and AIS patients. Our results showed that RIC substantially reduced BBB injury, intracerebral hemorrhage, cerebral infarction, and neurological deficits after stroke, even when rtPA was administrated in a delayed therapeutic time window. Mechanistically, RIC significantly decreased PDGFRα activation in ischemic brain tissue and reduced blood PDGF-CC levels, which partially resulted from PDGF-CC reduction in the skeletal muscle of RIC-applied hindlimbs and platelets. Intravenous or intraventricular recombinant PDGF-CC supplementation abolished RIC protective effects on BBB integrity. Moreover, similar changes of PDGF-CC in serum by RIC were also observed in healthy humans and acute ischemic stroke patients. Together, our study demonstrates that RIC can attenuate rtPA-aggravated BBB disruption after ischemic stroke via reducing the PDGF-CC/PDGFRα pathway and thus supports RIC as a potential approach for BBB disruption prevention or treatment following thrombolysis.

A review of remote ischemic conditioning as a potential strategy for neural repair poststroke

Ischemic stroke is one of the major disabling health-care problem and multiple different approaches are needed to enhance rehabilitation, in which neural repair is the structural basement. Remote ischemic conditioning (RIC) is a strategy to trigger endogenous protect. RIC has been reported to play neuroprotective role in acute stage of stroke, but the effect of RIC on repair process remaining unclear. Several studies have discovered some overlapped mechanisms RIC and neural repair performs. This review provides a hypothesis that RIC is a potential therapeutic strategy on stroke rehabilitation by evaluating the existing evidence and puts forward some remaining questions to clarify and future researches to be performed in the field.

The BE COOL Treatments (Batroxobin, oxygEn, Conditioning, and cOOLing): Emerging Adjunct Therapies for Ischemic Cerebrovascular Disease

Ischemic cerebrovascular disease (ICD), the most common neurological disease worldwide, can be classified based on the onset time (acute/chronic) and the type of cerebral blood vessel involved (artery or venous sinus). Classifications include acute ischemic stroke (AIS)/transient ischemic attack (TIA), chronic cerebral circulation insufficiency (CCCI), acute cerebral venous sinus thrombosis (CVST), and chronic cerebrospinal venous insufficiency (CCSVI). The pathogenesis of cerebral arterial ischemia may be correlated with cerebral venous ischemia through decreased cerebral perfusion. The core treatment goals for both arterial and venous ICDs include perfusion recovery, reduction of cerebral ischemic injury, and preservation of the neuronal integrity of the involved region as soon as possible; however, therapy based on the current guidelines for either acute ischemic events or chronic cerebral ischemia is not ideal because the recurrence rate of AIS or CVST is still very high. Therefore, this review discusses the neuroprotective effects of four novel potential ICD treatments with high translation rates, known as the BE COOL treatments (Batroxobin, oxygEn, Conditioning, and cOOLing), and subsequently analyzes how BE COOL treatments are used in clinical settings. The combination of batroxobin, oxygen, conditioning, and cooling may be a promising intervention for preserving ischemic tissues.

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.

Cerebral protection by remote ischemic post-conditioning in patients with ischemic stroke: A systematic review and meta-analysis of randomized controlled trials

Background

There is evidence that remote limb ischemic postconditioning (RIPostC) can reduce ischemia-reperfusion injury (IRI) and improve the prognosis of patients with ischemic stroke. However, so far, only few relevant clinical studies have been conducted. Therefore, we carried out a meta-analysis of eligible randomized controlled trials to compare the RIPostC group with a control group (no intervention or sham surgery) in patients with ischemic stroke.

Methods

Four English-language publication databases, PubMed, Cochrane, Embase, and Web of Science, were systematically searched up to March 2022. The data were analyzed using Review Manager fixed-effects and random-effects models.

Results

A total of 12 studies were included, and 11 of those were analyzed quantitatively. Compared to controls, The RIPostC group showed significantly reduced NIHHS scores in patients with ischemic stroke, (MD: −1.09, 95% confidence interval [CI]: −1.60, −0.57, P < 0.0001) and improved patients' Montreal Cognitive Assessment (MoCA) scores, (MD: 1.89, 95% CI: 0.78, 3.00, P = 0.0009), Our results showed that RIPostC is safe, (RR = 0.81, 95%CI: 0.61, 1.08, P = 0.15).

Conclusion

Our meta-analysis showed that RIPostC is safe and effective and has a positive cerebral protective effect in patients with ischemic stroke, which is safe and effective, and future large-sample, multicenter trials are needed to validate the cerebral protective effect of RIPostC.

Understanding Acquired Brain Injury: A Review

Any type of brain injury that transpires post-birth is referred to as Acquired Brain Injury (ABI). In general, ABI does not result from congenital disorders, degenerative diseases, or by brain trauma at birth. Although the human brain is protected from the external world by layers of tissues and bone, floating in nutrient-rich cerebrospinal fluid (CSF); it remains susceptible to harm and impairment. Brain damage resulting from ABI leads to changes in the normal neuronal tissue activity and/or structure in one or multiple areas of the brain, which can often affect normal brain functions. Impairment sustained from an ABI can last anywhere from days to a lifetime depending on the severity of the injury; however, many patients face trouble integrating themselves back into the community due to possible psychological and physiological outcomes. In this review, we discuss ABI pathologies, their types, and cellular mechanisms and summarize the therapeutic approaches for a better understanding of the subject and to create awareness among the public.

Effect of Remote Ischemic Conditioning vs Usual Care on Neurologic Function in Patients With Acute Moderate Ischemic Stroke: The RICAMIS Randomized Clinical Trial

IMPORTANCE

Preclinical and clinical studies have suggested a neuroprotective effect of remote ischemic conditioning (RIC), which involves repeated occlusion/release cycles on bilateral upper limb arteries; however, robust evidence in patients with ischemic stroke is lacking.

OBJECTIVE

To assess the efficacy of RIC for acute moderate ischemic stroke.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, open-label, blinded-end point, randomized clinical trial including 1893 patients with acute moderate ischemic stroke was conducted at 55 hospitals in China from December 26, 2018, through January 19, 2021, and the date of final follow-up was April 19, 2021.

INTERVENTIONS

Eligible patients were randomly assigned within 48 hours after symptom onset to receive treatment with RIC (using a pneumatic electronic device and consisting of 5 cycles of cuff inflation for 5 minutes and deflation for 5 minutes to the bilateral upper limbs to 200 mm Hg) for 10 to 14 days as an adjunct to guideline-based treatment (n = 922) or guideline-based treatment alone (n = 971).

MAIN OUTCOMES AND MEASURES

The primary end point was excellent functional outcome at 90 days, defined as a modified Rankin Scale score of 0 to 1. All end points had blinded assessment and were analyzed on a full analysis set.

RESULTS

Among 1893 eligible patients with acute moderate ischemic stroke who were randomized (mean [SD] age, 65 [10.3] years; 606 women [34.1%]), 1776 (93.8%) completed the trial. The number with excellent functional outcome at 90 days was 582 (67.4%) in the RIC group and 566 (62.0%) in the control group (risk difference, 5.4% [95% CI, 1.0%-9.9%]; odds ratio, 1.27 [95% CI, 1.05-1.54]; P = .02). The proportion of patients with any adverse events was 6.8% (59/863) in the RIC group and 5.6% (51/913) in the control group.

CONCLUSIONS AND RELEVANCE

Among adults with acute moderate ischemic stroke, treatment with remote ischemic conditioning compared with usual care significantly increased the likelihood of excellent neurologic function at 90 days. However, these findings require replication in another trial before concluding efficacy for this intervention.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03740971.

Remote ischaemic conditioning: defining critical criteria for success-report from the 11th Hatter Cardiovascular Workshop

The Hatter Cardiovascular Institute biennial workshop, originally scheduled for April 2020 but postponed for 2 years due to the Covid pandemic, was organised to debate and discuss the future of Remote Ischaemic Conditioning (RIC). This evolved from the large multicentre CONDI-2-ERIC-PPCI outcome study which demonstrated no additional benefit when using RIC in the setting of ST-elevation myocardial infarction (STEMI). The workshop discussed how conditioning has led to a significant and fundamental understanding of the mechanisms preventing cell death following ischaemia and reperfusion, and the key target cyto-protective pathways recruited by protective interventions, such as RIC. However, the obvious need to translate this protection to the clinical setting has not materialised largely due to the disconnect between preclinical and clinical studies. Discussion points included how to adapt preclinical animal studies to mirror the patient presenting with an acute myocardial infarction, as well as how to refine patient selection in clinical studies to account for co-morbidities and ongoing therapy. These latter scenarios can modify cytoprotective signalling and need to be taken into account to allow for a more robust outcome when powered appropriately. The workshop also discussed the potential for RIC in other disease settings including ischaemic stroke, cardio-oncology and COVID-19. The workshop, therefore, put forward specific classifications which could help identify so-called responders vs. non-responders in both the preclinical and clinical settings.

Cerebral Collateral Circulation in the Era of Reperfusion Therapies for Acute Ischemic Stroke

Clinical outcomes of patients with acute ischemic stroke depend in part on the extent of their collateral circulation. A good collateral circulation has also been associated with greater benefit of intravenous thrombolysis and endovascular treatment. Treatment decisions for these reperfusion therapies are increasingly guided by a combination of clinical and imaging parameters, particularly in later time windows. Computed tomography and magnetic resonance imaging enable a rapid assessment of both the collateral extent and cerebral perfusion. Yet, the role of the collateral circulation in clinical decision-making is currently limited and may be underappreciated due to the use of rather coarse and rater-dependent grading methods. In this review, we discuss determinants of the collateral circulation in patients with acute ischemic stroke, report on commonly used and emerging neuroimaging techniques for assessing the collateral circulation, and discuss the therapeutic and prognostic implications of the collateral circulation in relation to reperfusion therapies for acute ischemic stroke.

Remote ischemic conditioning for acute ischemic stroke part 2: Study protocol for a randomized controlled trial

Background

Remote ischemic conditioning (RIC) refers to the application of repeated short periods of ischemia intended to protect remote areas against tissue damage during and after prolonged ischemia.

Aim

We aim to evaluate the efficacy of RIC, determined by the modified Rankin Scale (mRS) score at 90 days after stroke onset.

Design and methods

This study is an investigator-initiated, multicenter, prospective, randomized, open-label, parallel-group clinical trial. The sample size is 400, comprising 200 patients who will receive RIC and 200 controls. The patients will be divided into three groups according to their National Institutes of Health Stroke Scale score at enrollment: 5–9, mild; 10–14, moderate; 15–20, severe. The RIC protocol will be comprised of four cycles, each consisting of 5 min of blood pressure cuff inflation (at 200 mmHg or 50 mmHg above the systolic blood pressure) followed by 5 min of reperfusion, with the cuff placed on the thigh on the unaffected side. The control group will only undergo blood pressure measurements before and after the intervention period. This trial is registered with the UMIN Clinical Trial Registry (https://www.umin.ac.jp/: UMIN000046225).

Study outcome

The primary outcome will be a good functional outcome as determined by the mRS score at 90 days after stroke onset, with a target mRS score of 0–1 in the mild group, 0–2 in the moderate group, and 0–3 in the severe group.

Discussion

This trial may help determine whether RIC should be recommended as a routine clinical strategy for patients with ischemic stroke.

Pilot Study of Remote Ischemic Conditioning in Acute Spontaneous Intracerebral Hemorrhage

Spontaneous Intracerebral hemorrhage (ICH) is a devastating injury that accounts for 10–15% of all strokes. The rupture of cerebral blood vessels damaged by hypertension or cerebral amyloid angiopathy creates a space-occupying hematoma that contributes toward neurological deterioration and high patient morbidity and mortality. Numerous protocols have explored a role for surgical decompression of ICH via craniotomy, stereotactic guided endoscopy, and minimally invasive catheter/tube evacuation. Studies including, but not limited to, STICH, STICH-II, MISTIE, MISTIE-II, MISTIE-III, ENRICH, and ICES have all shown that, in certain limited patient populations, evacuation can be done safely and mortality can be decreased, but functional outcomes remain statistically no different compared to medical management alone. Only 10–15% of patients with ICH are surgical candidates based on clot location, medical comorbidities, and limitations regarding early surgical intervention. To date, no clearly effective treatment options are available to improve ICH outcomes, leaving medical and supportive management as the standard of care. We recently identified that remote ischemic conditioning (RIC), the non-invasive, repetitive inflation-deflation of a blood pressure cuff on a limb, non-invasively enhanced hematoma resolution and improved neurological outcomes via anti-inflammatory macrophage polarization in pre-clinical ICH models. Herein, we propose a pilot, placebo-controlled, open-label, randomized trial to test the hypothesis that RIC accelerates hematoma resorption and improves outcomes in ICH patients. Twenty ICH patients will be randomized to receive either mock conditioning or unilateral arm RIC (4 cycles × 5 min inflation/5 min deflation per cycle) beginning within 48 h of stroke onset and continuing twice daily for one week. All patients will receive standard medical care according to latest guidelines. The primary outcome will be the safety evaluation of unilateral RIC in ICH patients. Secondary outcomes will include hematoma volume/clot resorption rate and functional outcomes, as assessed by the modified Rankin Scale (mRS) at 1- and 3-months post-ICH. Additionally, blood will be collected for exploratory genomic analysis. This study will establish the feasibility and safety of RIC in acute ICH patients, providing a foundation for a larger, multi-center clinical trial.

A Narrative Review on Translational Research in Acute Brain Injury

There has been a constant endeavor to reduce the mortality and morbidity associated with acute brain injury. The associated complex mechanisms involving biomechanics, markers, and neuroprotective drugs/measures have been extensively studied in preclinical studies with an ultimate aim to improve the patients' outcomes. Despite such efforts, only few have been successfully translated into clinical practice. In this review, we shall be discussing the major hurdles in the translation of preclinical results into clinical practice. The need is to choose an appropriate animal model, keeping in mind the species, age, and gender of the animal, choosing suitable outcome measures, ensuring quality of animal trials, and carrying out systematic review and meta-analysis of experimental studies before proceeding to human trials. The interdisciplinary collaboration between the preclinical and clinical scientists will help to design better, meaningful trials which might help a long way in successful translation. Although challenging at this stage, the advent of translational precision medicine will help the integration of mechanism-centric translational medicine and patient-centric precision medicine.

The Role of Plasma Extracellular Vesicles in Remote Ischemic Conditioning and Exercise-Induced Ischemic Tolerance

Ischemic conditioning and exercise have been suggested for protecting against brain ischemia-reperfusion injury. However, the endogenous protective mechanisms stimulated by these interventions remain unclear. Here, in a comprehensive translational study, we investigated the protective role of extracellular vesicles (EVs) released after remote ischemic conditioning (RIC), blood flow restricted resistance exercise (BFRRE), or high-load resistance exercise (HLRE). Blood samples were collected from human participants before and at serial time points after intervention. RIC and BFRRE plasma EVs released early after stimulation improved viability of endothelial cells subjected to oxygen-glucose deprivation. Furthermore, post-RIC EVs accumulated in the ischemic area of a stroke mouse model, and a mean decrease in infarct volume was observed for post-RIC EVs, although not reaching statistical significance. Thus, circulating EVs induced by RIC and BFRRE can mediate protection, but the in vivo and translational effects of conditioned EVs require further experimental verification.

Effects of Remote Ischemic Conditioning on Hand Engagement in individuals with Spinal cord Injury (RICHES): protocol for a pilot crossover study

​​​​​​Background: Most spinal cord injuries (SCI) are not full transections, indicating that residual nerve circuits are retained. Rehabilitation interventions have been shown to beneficially reorganize motor pathways in the brain, corticospinal tract, and at the spinal level. However, rehabilitation training require a large number of repetitions, and intervention effects may be absent or show transient retention. Therefore, the need remains for an effective approach to synergistically improve the amount and duration of neuroplasticity in combination with other interventions. Remote ischemic conditioning (RIC) demonstrates several potential advantages as a candidate for such an approach. Therefore, we propose a protocol to investigate RIC coupled with physical training to promote neuroplasticity in hand muscles. Methods: This will be a prospective randomized-order crossover trial to be performed in eight able-bodied participants and eight participants with chronic cervical SCI. Patients will participate in two experimental sessions consisting of either active or sham RIC preceding a bout of pinch movement exercise. Serial evaluations will be conducted at baseline, after RIC, immediately after pinch exercise, and follow up 15-minutes later. The primary outcome is the change in corticospinal excitability (primarily measured by the motor evoked potential of abductor pollicis brevis muscle). Secondary outcomes will include maximal volitional pinch force, and inflammatory biomarkers. To ensure safety, we will monitor tolerability and hemodynamic responses during RIC. Discussion: This protocol will be the first to test RIC in people with cervical SCI and to investigate whether RIC alters corticospinal excitability. By sharing the details of our protocol, we hope other interested researchers will seek to investigate similar approaches – depending on overlap with the current study and mutual sharing of participant-level data, this could increase the sample size, power, and generalizability of the analysis and results. Trial registration: ClinicalTrial.gov, ID: NCT03851302; Date of registration: February 22, 2019

Preventing Ischemic Cerebrovascular Events in High-Risk Patients With Non-disabling Ischemic Cerebrovascular Events Using Remote Ischemic Conditioning: A Single-Arm Study

Background: Secondary stroke prevention after a high-risk, non-disabling ischemic cerebrovascular event needs to be enhanced. The study was conducted to investigate whether remote ischemic conditioning (RIC) is effective in preventing recurrent ischemic events within 3 months.

Methods: This was a four-center, single-arm, open-label Phase IIa futility trial (PICNIC-One Study). Adult patients (≥18 years of age) who had an acute minor ischemic stroke (AMIS) with a National Institutes of Health Stroke Scale score ≤ 3 or a transient ischemic attack (TIA) with moderate-to-high risk of stroke recurrence (ABCD score ≥ 4) within 14 days of symptom onset were recruited. Patients received RIC as adjunctive therapy to routine secondary stroke prevention regimen. RIC consisted of five cycles of 5-min inflation (200 mmHg) and 5-min deflation of cuffs (45 min) on bilateral upper limbs twice a day for 90 days.

Results: A total of 285 patients met the study criteria, of which 167 provided signed informed consent and were enrolled. Data from 162 were analyzed with five subjects excluded. Recurrent AIS/TIA occurred in 6/162 (3.7%) patients within 3 months, with no occurrence of hemorrhagic stroke. The top three adverse events were upper limb pain (44/162, 27.2%), petechia (26/162, 16.0%), and heart palpitation (5/162, 3.1%). About 68 (42.0%) subjects completed ≥ 50% of 45-min RIC sessions.

Conclusions: RIC is a safe add-on procedure and it has a potential benefit in reducing recurrent cerebrovascular events in patients with high-risk, non-disabling ischemic cerebrovascular events as the risk of stroke/TIA events is lower than expected; however, its compliance needs to be improved. Our study provides critical preliminary data to plan a large sample size, randomized controlled clinical study to systematically investigate the safety and efficacy of RIC in this population.

Transient Ischemic Attacks Preceding Ischemic Stroke and the Possible Preconditioning of the Human Brain: A Systematic Review and Meta-Analysis

Stroke is a leading cause of mortality and disability worldwide. Transient ischemic attack (TIA) is defined as transient brain ischemia with temporary neurological deficits. In animal models, prior TIA seems to enhance brain ischemic tolerance to withstand further ischemic events, which might be explained by brain preconditioning. Thus, this review aims to formulate evidence of whether TIAs can induce positive preconditioning and enhance the functional outcomes in patients suffering from subsequent ischemic strokes. Five databases were searched (PubMed, Embase, SAGE, Web of Science, and Scopus), and twelve studies were included in the quantitative analysis. Studies were eligible when comparing patients with acute ischemic stroke (AIS) and previous TIA with those with AIS without TIA. Comparisons included the National Institute of Health Stroke Scale (NIHSS) score at admission and 7 days from the stroke event, modified Rankin score (mRS), and Trial of ORG 10,172 in Acute Stroke Treatment (TOAST) classification. Odds ratio (OR), mean difference (MD), and 95% confidence interval (CI) were used to describe our results using the random effect model. Our results revealed that patients with stroke and prior TIAs had lower NIHSS scores at admission than those without prior TIAs. However, the NIHSS score was not significantly different between the two groups at 7 days. Furthermore, there was no statistically significant difference between both groups in terms of mortality. Despite the differences in the admission mRS score groups, patients with prior TIAs had lower mRS scores at discharge.

Chronic Limb Remote Ischemic Conditioning may have an Antihypertensive Effect in Patients with Hypertension

Hypertension is the leading preventable risk factor for all-cause morbidity and mortality worldwide. Despite antihypertensive medications have been available for decades, a big challenge we are facing is to increase the blood pressure (BP) control rate among the population. Therefore, it is necessary to search for new antihypertensive means to reduce the burden of disease caused by hypertension. Limb remote ischemic conditioning (LRIC) can trigger endogenous protective effects through transient and repeated ischemia on the limb to protect specific organs and tissues including the brain, heart, and kidney. The mechanisms of LRIC involve the regulation of the autonomic nervous system, releasing humoral factors, improvement of vascular endothelial function, and modulation of immune/inflammatory responses. These underlying mechanisms of LRIC may restrain the pathogenesis of hypertension through multiple pathways theoretically, leading to a potential decline in BP. Several existing studies have explored the impact of LRIC on BP, however, controversial findings were reported. To explore the potential antihypertensive effect of LRIC and the underlying mechanisms, we systematically reviewed the relevant articles to provide an insight into the novel therapy of hypertension.

Remote Ischemic Conditioning in Ischemic Stroke and Myocardial Infarction: Similarities and Differences

Acute myocardial infarction and ischemic stroke are leading causes of morbidity and mortality worldwide. Although reperfusion therapies have greatly improved the outcomes of patients with these conditions, many patients die or are severely disabled despite complete reperfusion. It is therefore important to identify interventions that can prevent progression to ischemic necrosis and limit ischemia-reperfusion injury. A possible strategy is ischemic conditioning, which consists of inducing ischemia – either in the ischemic organ or in another body site [i.e., remote ischemic conditioning (RIC), e.g., by inflating a cuff around the patient's arm or leg]. The effects of ischemic conditioning have been studied, alone or in combination with revascularization techniques. Based on the timing (before, during, or after ischemia), RIC is classified as pre-, per-/peri-, or post-conditioning, respectively. In this review, we first highlight some pathophysiological and clinical similarities and differences between cardiac and cerebral ischemia. We report evidence that RIC reduces circulating biomarkers of myocardial necrosis, infarct size, and edema, although this effect appears not to translate into a better prognosis. We then review cutting-edge applications of RIC for the treatment of ischemic stroke. We also highlight that, although RIC is a safe procedure that can easily be implemented in hospital and pre-hospital settings, its efficacy in patients with ischemic stroke remains to be proven. We then discuss possible methodological issues of previous studies. We finish by highlighting some perspectives for future research, aimed at increasing the efficacy of ischemic conditioning for improving tissue protection and clinical outcomes, and stratifying myocardial infarction and brain ischemia patients to enhance treatment feasibility.

Multi-Center Randomized Phase II Clinical Trial on Remote Ischemic Conditioning in Acute Ischemic Stroke Within 9 Hours of Onset in Patients Ineligible to Recanalization Therapies (TRICS-9): Study Design and Protocol

Aim: To assess the efficacy of remote ischemic conditioning (RIC) in patients with ischemic stroke within 9 h of onset, that are not candidates for recanalization therapies. Sample Size Estimates: A sample size of 80 patients (40 in each arm) should yield 80% power to detect a 20% difference in early neurological improvement at 72 h at p = 0.05, two sided. Methods and Design: TRICS-9 is a phase II, multicenter, controlled, block randomized, open-label, interventional clinical trial. Patients recruited in Italian academic hospitals will be randomized 1:1 to either RIC plus standard medical therapy or standard medical therapy alone. After randomization, RIC will be applied manually by four alternating cycles of inflation/deflation 5 min each, using a blood pressure cuff around the non-paretic arm. Study Outcomes: The primary efficacy outcome is early neurological improvement, defined as the percent change in the National Institute of Health Stroke Scale (NIHSS) at 72 h in each arm. Secondary outcomes include early neurologic improvement at 24 and 48 h, disability at 3 months, rate of symptomatic intracerebral hemorrhage, feasibility (proportion of patients completing RIC), tolerability after RIC and at 72 h, blood levels of HIF-1α, and HSP27 at 24 h and 72 h. Discussion/Conclusion: RIC in combination with recanalization therapies appears to add no clinical benefit to patients, but whether it is beneficial to those that are not candidates for recanalization therapies is still to be demonstrated. TRICS-9 has been developed to elucidate this issue. Clinical Trial Registration: ClinicalTrials.gov, identifier: NCT04400981.

Remote but not Distant: a Review on Experimental Models and Clinical Trials in Remote Ischemic Conditioning as Potential Therapy in Ischemic Stroke

Stroke is one of the main causes of neurological disability worldwide and the second cause of death in people over 65 years old, resulting in great economic and social burden. Ischemic stroke accounts for 85% of total cases, and the approved therapies are based on re-establishment of blood flow, and do not directly target brain parenchyma. Thus, novel therapies are urgently needed. In this review, limb remote ischemic conditioning (RIC) is revised and discussed as a potential therapy against ischemic stroke. The review targets both (i) fundamental research based on experimental models and (ii) clinical research based on clinical trials and human interventional studies with healthy volunteers. Moreover, it also presents two approaches concerning RIC mechanisms in stroke: (i) description of the underlying cerebral cellular and molecular mechanisms triggered by limb RIC that promote neuroprotection against stroke induced damage and (ii) the identification of signaling factors involved in inter-organ communication following RIC procedure. Limb to brain remote signaling can occur via circulating biochemical factors, immune cells, and/or stimulation of autonomic nervous system. In this review, these three hypotheses are explored in both humans and experimental models. Finally, the challenges involved in translating experimentally generated scientific knowledge to a clinical setting are also discussed.

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.