Co-administration of tissue plasminogen activator and hyperbaric oxygen in ischemic stroke: a continued promise for neuroprotection

The Ketogenic Diet but not Hydroxycitric Acid Keeps Brain Mitochondria Quality Control and mtDNA Integrity Under Focal Stroke

Mitochondrial dysfunction in the ischemic brain is one of the hallmarks of stroke. Dietary interventions such as the ketogenic diet and hydroxycitric acid supplementation (a caloric restriction mimetic) may potentially protect neurons from mitochondrial damage induced by focal stroke in mice. We showed that in control mice, the ketogenic diet and the hydroxycitric acid did not impact significantly on the mtDNA integrity and expression of genes involved in the maintenance of mitochondrial quality control in the brain, liver, and kidney. The ketogenic diet changed the bacterial composition of the gut microbiome, which via the gut-brain axis may affect the increase in anxiety behavior and reduce mice mobility. The hydroxycitric acid causes mortality and suppresses mitochondrial biogenesis in the liver. Focal stroke modelling caused a significant decrease in the mtDNA copy number in both ipsilateral and contralateral brain cortex and increased the levels of mtDNA damage in the ipsilateral hemisphere. These alterations were accompanied by a decrease in the expression of some of the genes involved in maintaining mitochondrial quality control. The ketogenic diet consumption before stroke protects mtDNA in the ipsilateral cortex, probably via activation of the Nrf2 signaling. The hydroxycitric acid, on the contrary, increased stroke-induced injury. Thus, the ketogenic diet is the most preferred variant of dietetic intervention for stroke protection compared with the hydroxycitric acid supplementation. Our data confirm some reports about hydroxycitric acid toxicity, not only for the liver but also for the brain under stroke condition.

GAS6/Axl Signaling Modulates Blood-Brain Barrier Function Following Intravenous Thrombolysis in Acute Ischemic Stroke

Background and Purpose

Recent studies have shown that several proteins, including Axl, are related to hemorrhagic transformation (HT) following intravenous thrombolysis by affecting blood-brain barrier (BBB) function. However, the effects of these proteins on BBB function have been studied primarily in animal models. In this study, we aimed to identify serum protein markers that predict HT following intravenous thrombolysis in patients with acute ischemic stroke (AIS) and verify whether these serum proteins regulate BBB function and HT in animal stroke models.

Methods

First, 118 AIS patients were enrolled in this study, including 52 HT patients and 66 non-HT patients. In Step 1, baseline serum levels of Axl, angiopoietin-like 4, C-reactive protein, ferritin, hypoxia-inducible factor-1 alpha, HTRA2, Lipocalin2, matrix metallopeptidase 9, platelet-derived growth factor-BB, and tumor necrosis factor alpha were measured using a quantitative cytokine chip. Next, sequence mutations and variations in genes encoding the differentially expressed proteins identified in Step 1 and subsequent function-related proteins were detected. Finally, we verified whether manipulation of differentially expressed proteins affected BBB function and HT in a hyperglycemia-induced rat stroke model.

Results

Serum Axl levels were significantly lower in the HT group than in the non-HT group; none of the other protein markers differed significantly between the two groups. Genetic testing revealed that sequence variations of GAS6 (the gene encoding the Axl ligand)-derived long non-coding RNA, GAS6-AS1, were significantly correlated with an increased risk of HT after intravenous thrombolysis. In animal studies, administration of recombinant GAS6 significantly reduced brain infarction and neurological deficits and attenuated BBB disruption and HT.

Conclusions

Lower serum Axl levels, which may result from sequence variations in GAS6-AS1, are correlated with an increased risk of HT after intravenous thrombolysis in stroke patients. Activation of the Axl signaling pathway by the GAS6 protein may serve as a therapeutic strategy to reduce HT in AIS patients.

Effects of alteplase on neurological deficits and expression of GFAP and GAP-43 in brain tissue of rats with acute cerebral infarction

OBJECTIVE

To investigate the effects of alteplase on neurological deficits, as well as on the expressions of glial fibrillary acidic protein (GFAP) and growth-associated protein-43 (GAP-43) in brain tissues of rats with acute cerebral infarction (ACI).

METHODS

Sprague Dawley (SD) rats (n = 50) were enrolled in a trial to establish a ACI rat model; of these, 48 rats were succeeefully modeled and were randomized into either the model or alteplase group, whereas another 24 SD rats were included in the sham-operated group.

FINDINGS

No significant difference in scores was observed between the model and alteplase groups at T1 (P > 0.05); however, rats in the alteplase group demonstrated lower scores than those in the model group at T2, T3, and T4 (P < 0.05). Rats in the model group showed a larger cerebral infarction volume than those in the alteplase group (P < 0.05), and the infarction volume on day 1, 3, 6, and 9 was higher in rats in the alteplase group than those in the sham-operated group (P < 0.05).

CONCLUSION

Treatment with alteplase can be effective in reducing cerebral infarction volume and moderating neurological deficits in ACI modeled rats within a 6-h time window, which may be correlated with the regulation of GFAP and GAP-43 expressions by alteplase.

Successful intravenous thrombolysis for acute ischemic stroke caused by aortic dissection with severe hypofibrinogenemia: a case report and literature review

BACKGROUND

Intravenous thrombolysis (IVT) for acute brain infarctions caused by aortic dissection (AD) may lead to fatal outcomes; thus, it should be ruled out, especially if hypofibrinogenemia occurs after IVT. Successful management of AD-related acute brain infarction with hypofibrinogenemia after IVT has not been reported previously.

CASE REPORT

An 84-year-old woman developed sudden left limb weakness and aphasia for almost 4 h. Alteplase was administered intravenously immediately after cerebral hemorrhage was ruled out by emergent head computed tomography (CT). An anomaly suspected to be AD was detected during subsequent routine chest CT, which was confirmed by CT angiography to be a thoracoabdominal aortic dissecting aneurysm (DeBakey type I). Severe hypofibrinogenemia was also noted. After effective blood pressure control, intramuscular injection of vitamin K, and rehydration therapy, her brain cell metabolism improved, hemiplegia improved slightly, and hypofibrinogenemia recovered gradually. The patient's cerebral hemorrhage did not progress, there was no chest pain or no aggravation of hemiplegia, and the fibrinogen level gradually returned to normal. The condition was stable during hospitalization. At 1.5 months after discharge, the patient showed minimal change in condition.

CONCLUSION

The symptoms of AD may be nonspecific and latent. IVT may be allowed to perform for some patients with AD related ischemical stroke, And IVT can improve the neural symptoms of AD-related ischemic stroke, but close monitoring is needed to avoid aneurysm rupture. Fibrinogen levels should also be monitored periodically after IVT for early detection of hypofibrinogenemia.

The Effect of Hyperbaric Oxygen Therapy on Functional Impairments Caused by Ischemic Stroke

Background

While research suggests a benefit of hyperbaric oxygen therapy (HBOT) for neurologic injury, controlled clinical trials have not been able to clearly define the benefits.

Objective

To investigate the effects of HBOT on physical and cognitive impairments resulting from an ischemic stroke.

Methods

Using a within-subject design a baseline for current functional abilities was established over a 3-month period for all subjects (n=7). Each subject then received two 4-week periods of HBOT for a total of 40 90-minute treatments over a 12-week period. Subjects completed a battery of assessments and had blood drawn six times over the 9-month total duration of the study.

Results

We found improvements in cognition and executive function as well as physical abilities, specifically, improved gait. Participants reported improved sleep and quality of life following HBOT treatment. We also saw changes in serum levels of biomarkers for inflammation and neural recovery. In the functional domains where improvement was observed following HBOT treatment, the improvements were maintained up to 3 months following the last treatment. However, the physiological biomarkers showed a pattern of more transient changes following HBOT treatment.

Conclusions

Findings from this study support the idea of HBOT as a potential intervention following stroke.

Mitochondria in Ischemic Stroke: New Insight and Implications

Stroke is the leading cause of death and adult disability worldwide. Mitochondrial dysfunction has been regarded as one of the hallmarks of ischemia/reperfusion (I/R) induced neuronal death. Maintaining the function of mitochondria is crucial in promoting neuron survival and neurological improvement. In this article, we review current progress regarding the roles of mitochondria in the pathological process of cerebral I/R injury. In particular, we emphasize on the most critical mechanisms responsible for mitochondrial quality control, as well as the recent findings on mitochondrial transfer in acute stroke. We highlight the potential of mitochondria as therapeutic targets for stroke treatment and provide valuable insights for clinical strategies.

Targeting vascular inflammation in ischemic stroke: Recent developments on novel immunomodulatory approaches

Ischemic stroke is a devastating and debilitating medical condition with limited therapeutic options. However, accumulating evidence indicates a central role of inflammation in all aspects of stroke including its initiation, the progression of injury, and recovery or wound healing. A central target of inflammation is disruption of the blood brain barrier or neurovascular unit. Here we discuss recent developments in identifying potential molecular targets and immunomodulatory approaches to preserve or protect barrier function and limit infarct damage and functional impairment. These include blocking harmful inflammatory signaling in endothelial cells, microglia/macrophages, or Th17/γδ T cells with biologics, third generation epoxyeicosatrienoic acid (EET) analogs with extended half-life, and miRNA antagomirs. Complementary beneficial pathways may be enhanced by miRNA mimetics or hyperbaric oxygenation. These immunomodulatory approaches could be used to greatly expand the therapeutic window for thrombolytic treatment with tissue plasminogen activator (t-PA). Moreover, nanoparticle technology allows for the selective targeting of endothelial cells for delivery of DNA/RNA oligonucleotides and neuroprotective drugs. In addition, although likely detrimental to the progression of ischemic stroke by inducing inflammation, oxidative stress, and neuronal cell death, 20-HETE may also reduce susceptibility of onset of ischemic stroke by maintaining autoregulation of cerebral blood flow. Although the interaction between inflammation and stroke is multifaceted, a better understanding of the mechanisms behind the pro-inflammatory state at all stages will hopefully help in developing novel immunomodulatory approaches to improve mortality and functional outcome of those inflicted with ischemic stroke.

Oxygen Supplementation Ameliorates Tibial Development via Stimulating Vascularization in Tibetan Chickens at High Altitudes

Tibetan chickens (TBCs) living in high-altitude hypoxic environment, are characterized by delayed growth and small size as compared to low-altitude broiler chickens. Increasing evidences signify the beneficial effect of oxygen (O₂) supplementation in animal's body for regulating their body growth and organ development. However, it is still unclear that whether O₂ supplementation has an ameliorative and protective role in TBCs living at high altitude. In this study, we first found that O₂ supplementation not only increased the survival rate but also promoted the growth of TBCs associated with bone development. Importantly, we observed that the increase of vascular distribution in the tibial hypertrophic zone could contribute to promote growth and development of the tibia, which is highly correlated with the up-regulated expression level of vascular endothelial growth factor (VEGF)-A and VEGF receptor-1 (VEGFR1). Additionally, hypoxia inducible factor (HIF)-1ɑ also has a stimulative elevation by O₂ supplementation. These results were confirmed by histology, immunohistochemistry, qRT-PCR and Western blotting techniques. Altogether, these findings demonstrated that the up-regulation of VEGFA and its receptors are accompanied by proangiogeneic factor (HIF-1α) expression, which were required for angiogenesis to meliorate tibia development of TBCs in hypoxia-induced bone suppression that occurred during O₂ supplementation. Thus, O₂ supplementation may serve as a good applicant for promoting and meliorating bone development in juvenile high-altitude animals.