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  • 1
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 50, No. Suppl_1 ( 2019-02)
    Abstract: Introduction: In the pathophysiology of ischemic stroke, Leptomeningeal collateral circulation plays a key role on the severity of infarction. Balb/C mice have impaired leptomeningeal collateral due to variants of Rabep2 on chromosome 7 ( Candq1 ), causing sever stroke compared to C57BL/6 mice with rich collateral anastomosis. However, it still remains unclear whether and how poor collateral circulation specifically affects hemodynamic adaptation of microvessels during cerebral ischemia. Method: Male C57BL/6 and Balb/C mice were subjected to distal middle cerebral artery occlusion (dMCAO) combined with 90 minutes-occlusion of the ipsilateral common carotid artery. A 4x4 mm 2 cranial window was created on the parietal cortex 2 mm lateral and 1 mm posterior from the bregma 3 weeks prior to imaging. Spatial and temporal changes of the total flow and axial velocity of the penetrating arterioles (PA), as well as mean transit time (MTT) and capillary transit time heterogeneity (CTTH) in the capillaries bordering the distal MCA and ACA branches were determined by optical coherent tomography-based microangiography and capillary velocimetry at baseline, during dMCAO, 1 hour, 1 day and 7 days after reperfusion in each strain. Results: Stroke-induced increase in CTTH in the region of middle cerebral artery was significantly greater in Balb/C compared to C57BL/6 mice, leading to significantly increased microvascular resistance and reduced oxygen extraction during MCAO and 1 hour after reperfusion in the former (P 〈 0.05). The total blood flow in PA reduced immediately after dMCAO in both strains of mice but it remained reduced in Balb/C mice after reperfusion in contrast to a sustainable recovery at 50% of prestroke level 7 days after stroke. Conclusion: Poor collateral anastomosis and impaired flow of penetrating arterioles is an additional risk factor for hemodynamic compromise during cerebral ischemia caused by reduced oxygen extraction, which may increase the severity of stroke.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2019
    detail.hit.zdb_id: 1467823-8
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  • 2
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 46, No. suppl_1 ( 2015-02)
    Abstract: Objective: Previously we have found that stroke by distal occlusion of the middle cerebral artery (dMCAO) produced injury restricted to the parietal cortex yet hippocampal impairment. Recent advances in functional connectivity suggest that shared neuronal activation patterns or synchronized brain oscillation define brain networks linking anatomically separate brain regions. Using in vivo electrophysiology, the current study aimed to determine the temporal profile of stroke-induced changes in brain oscillation in the hippocampus, a remote brain region that does not suffer from ischemic injury. Methods: Adult male rats were subjected to either a permanent left MCAO combined with a temporary bilateral occlusion of the common carotid artery (CCAO), or bilateral CCAO alone, for 1 hour. Bilateral extracellular recording was performed under urethane anesthesia using the 32-channel NeuroNexus probes spanning the cortex and CA1 radiatum layer. Results: During reperfusion, a significant decrease in theta-to-delta ratio (T/D) was observed in rats that underwent either dMCAO or CCAO alone. However, a sustained delta predominant state was only observed chronically after dMCAO, suggesting a persistent disruption of hippocampal-neocortical connectivity in the former. In contrast to CCAO, dMCAO also induced a reduced low gamma (30-59 Hz) power, change in dominant theta-frequency and disassociation of theta-gamma coupling. Conclusions: Our results indicate that ischemic stroke induces specific changes in hippocampal oscillations that might underlie the observed cognitive impairment. In contrast to stroke, an episode of mild ischemia by temporary CCAO that does not trigger functional impairment also does not evoke persistent changes in hippocampal oscillations. The observed brain oscillation profile specific to dMCAO offers an integrated measurement of the hippocampal-dependent network activity, and may serve as a candidate biomarker for post-stroke cognitive impairment.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2015
    detail.hit.zdb_id: 1467823-8
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  • 3
    Online Resource
    Online Resource
    Elsevier BV ; 2015
    In:  Brain Research Vol. 1623 ( 2015-10), p. 18-29
    In: Brain Research, Elsevier BV, Vol. 1623 ( 2015-10), p. 18-29
    Type of Medium: Online Resource
    ISSN: 0006-8993
    RVK:
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2015
    detail.hit.zdb_id: 1462674-3
    SSG: 12
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  • 4
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 47, No. 12 ( 2016-12), p. 3014-3021
    Abstract: The presence of collaterals is associated with a reduced risk of stroke and transient ischemic attack in patients with steno-occlusive carotid artery disease. Although metabolic syndrome negatively impacts collateral status, it is unclear whether and to what extent type 2 diabetes mellitus affects cerebral collateral flow regulation during hypoperfusion. Methods— We examined the spatial and temporal changes of the leptomeningeal collateral flow and the flow dynamics of the penetrating arterioles in the distal middle cerebral artery and anterior cerebral artery branches over 2 weeks after unilateral common carotid artery occlusion (CCAO) using optical coherent tomography in db/+ and db/db mice. We also assessed the temporal adaptation of the circle of Willis after CCAO by measuring circle of Willis vessel diameters. Results— After unilateral CCAO, db/db mice exhibited diminished leptomeningeal collateral flow compensation compared with db /+ mice, which coincided with a reduced dilation of distal anterior cerebral artery branches, leading to reduced flow not only in pial vessels but also in penetrating arterioles bordering the distal middle cerebral artery and anterior cerebral artery. However, no apparent cell death was detected in either strain of mice during the first week after CCAO. db/db mice also experienced a more severe early reduction in the vessel diameters of several ipsilateral main feeding arteries in the circle of Willis, in addition to a delayed post-CCAO adaptive response by 1 to 2 weeks, compared with db/+ mice. Conclusions— Type 2 diabetes mellitus is an additional risk factor for hemodynamic compromise during cerebral hypoperfusion, which may increase the severity and the risk of stroke or transient ischemic attack.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2016
    detail.hit.zdb_id: 1467823-8
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  • 5
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 48, No. suppl_1 ( 2017-02)
    Abstract: Introduction: The degree of cortical hypoperfusion following carotid steno-occlusion depends on the dynamic compensation from the collateral circulation. The presence of collaterals is associated with a reduced risk of stroke and transient ischemic attack (TIA) in patients with steno-occlusive carotid artery disease. Although metabolic syndrome negatively impacts collateral status among patients with ischemic stroke, it is unclear whether type 2 diabetes (T2DM) specifically affects leptomeningeal collateral flow regulation and the adaptation of collateral vessels at the circle of Willis during hypoperfusion. Methods: Spatial and temporal changes of the leptomeningeal collateral flow and the flow dynamics of the penetrating arterioles in the distal MCA and ACA branches over two weeks following unilateral common carotid artery occlusion (CCAO) were determined by optical coherent tomography in db/+ and db/db mice, a mouse model for obesity and type 2 diabetes. The temporal adaptation of the circle of Willis (CW) following CCAO was assessed by measuring CW vessel diameters. Results: Following unilateral CCAO, db/db mice exhibited diminished leptomeningeal collateral flow compensation compared to db /+ mice, which coincided with a reduced dilation of distal ACA branches, leading to reduced flow not only in pial vessels, but also in penetrating arterioles bordering the distal MCA and ACA. However, no apparent cell death was detected in either strain of mice during the first week after CCAO. db/db mice also experienced a more severe early reduction in the vessel diameters of several ipsilateral main feeding arteries in the CW, in addition to a delayed post-CCAO adaptive response by one to two weeks compared to db/+ mice. Conclusions: T2DM is an additional risk factor for hemodynamic compromise during cerebral hypoperfusion, which may increase the severity and the risk of stroke or TIA.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    RVK:
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2017
    detail.hit.zdb_id: 1467823-8
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  • 6
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 35, No. 9 ( 2015-03-04), p. 3851-3864
    Abstract: Collateral status is an independent predictor of stroke outcome. However, the spatiotemporal manner in which collateral flow maintains cerebral perfusion during cerebral ischemia is poorly understood. Diabetes exacerbates ischemic brain damage, although the impact of diabetes on collateral dynamics remains to be established. Using Doppler optical coherent tomography, a robust recruitment of leptomeningeal collateral flow was detected immediately after middle cerebral artery (MCA) occlusion in C57BL/6 mice, and it continued to grow over the course of 1 week. In contrast, an impairment of collateral recruitment was evident in the Type 2 diabetic db/db mice, which coincided with a worse stroke outcome compared with their normoglycemic counterpart db/ +, despite their equally well-collateralized leptomeningeal anastomoses. Similar to the wild-type mice, both db/ + and db/db mice underwent collateral growth 7 d after MCA stroke, although db/db mice still exhibited significantly reduced retrograde flow into the MCA territory chronically. Acutely induced hyperglycemia in the db/ + mice did not impair collateral flow after stroke, suggesting that the state of hyperglycemia alone was not sufficient to impact collateral flow. Human albumin was efficacious in improving collateral flow and outcome after stroke in the db/db mice, enabling perfusion to proximal MCA territory that was usually not reached by retrograde flow from anterior cerebral artery without treatment. Our results suggest that the impaired collateral status contributes to the exacerbated ischemic injury in mice with Type 2 diabetes, and modulation of collateral flow has beneficial effects on stroke outcome among these subjects.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2015
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 7
    In: Journal of Neurosurgery, Journal of Neurosurgery Publishing Group (JNSPG), Vol. 123, No. 1 ( 2015-07), p. 243-253
    Abstract: Numerous studies have attempted to reveal the pathophysiology of ischemic neuronal injury using a representative transient global cerebral ischemia (tGCI) model in rodents; however, most of them have used gerbil or rat models. Recent advances in transgene and gene-knockout technology have enabled the precise molecular mechanisms of ischemic brain injury to be investigated. Because the predominant species for the study of genetic mutations is the mouse, a representative mouse model of tGCI is of particular importance. However, simple mouse models of tGCI are less reproducible; therefore, a more complex process or longer duration of ischemia, which causes a high mortality rate, has been used in previous tGCI models in mice. In this study, the authors aimed to overcome these problems and attempted to produce consistent unilateral delayed hippocampal CA1 neuronal death in mice. METHODS C57BL/6 mice were subjected to short-term unilateral cerebral ischemia using a 4-mm silicone-coated intraluminal suture to obstruct the origin of the posterior cerebral artery (PCA), and regional cerebral blood flow (rCBF) of the PCA territory was measured using laser speckle flowmetry. The mice were randomly assigned to groups of different ischemic durations and histologically evaluated at different time points after ischemia. The survival rate and neurological score of the group that experienced 15 minutes of ischemia were also evaluated. RESULTS Consistent neuronal death was observed in the medial CA1 subregion 4 days after 15 minutes of ischemia in the group of mice with a reduction in rCBF of 〈 65% in the PCA territory during ischemia. Morphologically degenerated cells were mostly positive for terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling and cleaved caspase 3 staining 4 days after ischemia. The survival rates of the mice 24 hours (n = 24), 4 days (n = 15), and 7 days (n = 7) after being subjected to 15 minutes of ischemia were 95.8%, 100%, and 100%, respectively, and the mice had slight motor deficits. CONCLUSIONS The authors established a model of delayed unilateral hippocampal neuronal death in C57BL/6 mice by inducing ischemia in the PCA territory using an intraluminal suture method and established inclusion criteria for PCAterritory rCBF monitored by laser speckle flowmetry. This model may be useful for investigating the precise molecular mechanisms of ischemic brain injury.
    Type of Medium: Online Resource
    ISSN: 0022-3085 , 1933-0693
    RVK:
    RVK:
    Language: Unknown
    Publisher: Journal of Neurosurgery Publishing Group (JNSPG)
    Publication Date: 2015
    detail.hit.zdb_id: 2026156-1
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