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Cited by 120Acute Ischemic Stroke ManagementNeurological Disease Mechanisms and TreatmentsNeuroinflammation and Neurodegeneration Mechanisms

Two-Photon Imaging during Prolonged Middle Cerebral Artery Occlusion in Mice Reveals Recovery of Dendritic Structure after Reperfusion

Open access
Li, Ping, Murphy, Timothy H.·2008·The Journal of Neuroscience
DOI 10.1523/jneurosci.3724-08.2008PMC PMC6671659
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Abstract

Filament occlusion of the middle cerebral artery (MCA) is a well accepted animal model of focal ischemia. Advantages of the model are relatively long occlusion times and a large penumbra region that simulates aspects of human stroke. Here, we use two-photon and confocal microscopy in combination with regional measurement of blood flow using laser speckle to assess the spatial relationship between the borders of the MCA ischemic territory and loss of dendrite structure, as well as the effect of reperfusion on dendritic damage in adult YFP (yellow fluorescent protein) and GFP (green fluorescent protein) C57BL/6 transgenic mice with fluorescent (predominantly layer 5) neurons. By examining the spatial extent of dendritic damage, we determined that 60 min of MCA occlusion produced a core with severe structural damage that did not recover after reperfusion (begins ∼3.8 mm lateral to midline), a reversibly damaged area up to 0.6 mm medial to the core that recovered after reperfusion (penumbra), and a relatively structurally intact area (∼1 mm wide; medial penumbra) with hypoperfusion. Loss of structure was preceded by a single ischemic depolarization 122.1 ± 10.2 s after occlusion onset. Reperfusion of animals after 60 min of ischemia was not associated with exacerbation of damage (reperfusion injury) and resulted in a significant restoration of blebbed dendritic structure, but only within ∼0.6 mm lateral of the dendritic damage structural border. In summary, we find that recovery of dendritic structure can occur after reperfusion after even 60 min of ischemia, but is likely restricted to a relatively small penumbra region with partial blood flow or oxygenation.

AI snapshot

Written from the paper’s full text.

TL;DR

In adult transgenic mice with fluorescent cortical neurons, 60 min of middle cerebral artery occlusion caused severe dendritic blebbing in the ischemic core that did not recover after reperfusion, but dendritic structure recovered in a narrow penumbral region. Recovery after prolonged focal ischemia was limited to roughly 0.6 mm lateral of the dendritic damage border and did not extend into the core.

Key findings

  • After 60 min MCAO, there was a core with severe structural damage that did not recover after reperfusion (beginning ~3.8 mm lateral to midline), a reversibly damaged area up to 0.6 mm medial to the core that recovered after reperfusion, and a relatively structurally intact hypoperfused area ~1 mm wide medially.
  • Loss of dendritic structure was preceded by a single ischemic depolarization at 122.1 ± 10.2 s after occlusion onset; the DC shift amplitude was smaller after MCAO (9 ± 1 mV, n = 7) than after global ischemia (12 ± 1 mV, n = 8; p < 0.05).
  • Dendritic beading decreased from 65 ± 4% to 33 ± 4% (n = 8 animals) when moving from the structural border toward the midline; after reperfusion, recovery within 300 µm lateral of the border was almost complete, with partial recovery from 300 to 600 µm.
  • Blood flow dropped to 16 ± 4% of baseline by laser Doppler after suture occlusion and to 24 ± 3% of baseline by laser speckle during MCAO; reperfusion restored flow to 70 ± 6% of pre-CCA occlusion levels, and no reperfusion injury exacerbation was observed in the penumbra.

Methods

  • Used 22 adult male YFP-H and GFP-M transgenic mice (9–15 weeks, 23–31 g) under urethane anesthesia; MCAO was induced by intraluminal suture for ~60 min followed by reperfusion, with two-photon and confocal imaging of layer 5 dendritic tufts, laser Doppler, laser speckle imaging, EEG/DC potential recording, and histology.
  • Dendritic blebbing was scored from two-photon images by blinded observers as the fraction of 20 µm dendritic segments appearing normal or blebbed; statistical comparisons used ANOVA with Bonferroni post hoc tests or t tests, with data expressed as mean ± SEM.

Limitations

  • Stated by the paper: animals were not imaged beyond 3 h after reperfusion; the lateral MCA core was difficult to access with two-photon imaging because of cortical curvature; permanent CCA ligation meant reperfusion reached only ~70–75% of prestroke flow; individual spine loss could not be quantified; and small periinfarct depolarizations may have gone undetected.
  • Evident from the text: some analyses relied on small samples, including n = 2 animals for repeated beading during occlusion, n = 4 for unilateral CCAO controls, n = 5 for histological core assessment, and n = 8 for reperfusion recovery; recovery measurements were also limited by the craniotomy window.

Model-written summary. Check it against the paper before relying on it.

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Registry

Crossref · 10.1523/jneurosci.3724-08.2008

Cites

47 of 47 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 40 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The core structural damage did not recover after reperfusion.

    “did not recover after reperfusion”
    Quote in the paperSubstantial claim
  • Findingown data

    A relatively sharp dendritic structural transition from blebbed to relatively intact occurred at 3.1 ± 0.1 mm lateral to midline (n = 9 animals).

    “These image stacks indicated a relatively sharp dendritic structural transition from blebbed to relatively intact at 3.1 Ϯ 0.1 mm lateral to midline (n ϭ 9 animals)”
    Quote in the paperSubstantial claim
  • Findingown data

    Spared arteries with little or no block of blood flow by MCAO were often found.

    “we often found spared arteries with little or no block of blood flow by MCAO”
    Quote in the paperNot a substantial claim
  • Findingown data

    An area up to 1 mm medial to the structural border was hypoperfused but contained relatively intact dendritic structure.

    “an area up to 1 mm medial to the structural border was hypoperfused (see examples in Figs.3A, 5C, and the average of all animals in Fig. 7A), but contained relatively intact dendritic structure.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: The velocity of blood flow is proportional to the inverse of the speckle contrast.
  • Findingown data

    Moving toward the midline away from the MCA territory, mostly intact dendritic structure was found.

    “Moving toward the midline away from the MCA territory, we found mostly intact dendritic structure.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 37
  • Classified as probably not a substantial claim. 20

  • May combine two claims.

    Findingown data

    Within seconds of occlusion, a strong reduction in spontaneous EEG power occurred, consistent with ischemia blocking ongoing synaptic activity.

    “Within seconds of occlusion, we observed a strong reduction in spontaneous EEG power consistent with ischemia blocking ongoing synaptic activity”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Reperfusion resulted in significant restoration of blebbed dendritic structure, but only within approximately 0.6 mm lateral of the dendritic damage structural border.

    “resulted in a significant restoration of blebbed dendritic structure, but only within ϳ0.6 mm lateral of the dendritic damage structural border.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The light gray area, ~1 mm medial to the structural border, is where blood flow was reduced and dendritic structure remained mostly intact.

    “The light gray area, which is ϳ1 mm medial to the structural border, is where the blood flow was reduced (according to speckle laser data) and the dendritic structure remained mostly intact (according to two-photon microscopy data).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Recovery of structure began gradually after approximately 20-30 min of reperfusion and in some cases resulted in dendrites nearly identical with prestroke conditions.

    “Recovery of structure began gradually after ϳ20 -30 min of reperfusion and in some cases resulted in the appearance of dendrites that were nearly identical with prestroke conditions”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In animals successfully reperfused for 1.5-3 h, there were still blebbed dendrites within the MCA core region despite partial recovery of penumbra dendrites.

    “To further check this in even more lateral areas, we did histological studies and observed that, in animals successfully reperfused for 1.5-3 h, there were still blebbed dendrites within the MCA core region despite the observation (using two-photon imaging) that penumbra dendrites in part recovered (Fig. 6).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The area up to ~1 mm medial to the structural border was hypoperfused but relatively structurally intact.

    “This analysis shows that the area up to ϳ1 mm medial to the structural border was hypoperfused but relatively structurally intact.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Axons within the striatum of the ischemic hemisphere were beaded after reperfusion, but not in the contralateral hemisphere.

    “Axons within the striatum of the ischemic hemisphere were also beaded, but not in the contralateral hemisphere (Fig. 6 E, F ).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    Blebbed dendritic structure was greatest near the brain surface, consistent with a previous histological study with permanent MCAO.

    “Interestingly, blebbed dendritic structure was greatest near the brain surface consistent with a histological study we had done previously with permanent MCAO (Enright et al., 2007).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Enright et al., 2007

      Not checked in the free run.

  • May combine two claims.

    Findingown data

    The percentages of dendritic blebbing are significantly different between prestroke control and during MCAO, and between during MCAO and after reperfusion, at all distances (p < 0.05, by two-way ANOVA).

    “The percentagesofdendriticblebbingaresignificantdifferentbetweenprestrokecontrolandduringMCAO,duringMCAO,andafterreperfusion at all distances ( p Ͻ 0.05, by two-way ANOVA).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Between prestroke control and after reperfusion, dendritic blebbing is significantly different at 450 and >600 μm from the structural border, but not at other distances.

    “Between prestroke control and after reperfusion, it is significantly different at 450 and Ͼ600 m from the structural border, but not at other distances.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Reperfusion after 60 min of ischemia resulted in significant restoration of blebbed dendritic structure, but only within about 0.6 mm lateral of the dendritic damage structural border.

    “and resulted in a significant restoration of blebbed dendritic structure, but only within ϳ0.6 mm lateral of the dendritic damage structural border.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    After reperfusion, dendrites within the ischemic penumbra can recover, but recovery is limited to a small region and does not extend to the ischemic core.

    “After reperfusion, dendrites within the ischemic penumbra can recover, but recovery is limited to a small region and does not extend to the ischemic core.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Recovery of dendritic structure began gradually after about 20-30 min of reperfusion and in some cases resulted in dendrites nearly identical with prestroke conditions.

    “Recovery of structure began gradually after ϳ20 -30 min of reperfusion and in some cases resulted in the appearance of dendrites that were nearly identical with prestroke conditions (Fig. 5 B, C).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    The EEG electrodes used measure signals from areas up to 1 mm away with <50% signal attenuation.

    “Using surface stimulation, we estimate that the EEG electrodes used will measure signals from areas up to 1 mm away with Ͻ50% signal attenuation (our unpublished data).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In the right panel, the animal was reperfused and a significant recovery of dendritic structure was observed.

    “In the right panel, the animal was reperfused and a significant recovery of dendritic structure was observed.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    In the middle panel, a projection image is shown 52 min after MCAO and extensive dendritic blebbing is observed.

    “In the middle panel, a projection image is shown 52 min after MCAO and extensive dendritic blebbing is observed.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Reperfusion was less effective at normalizing dendritic structure in more lateral regions, with the most lateral areas of the craniotomy showing the lowest potential for recovery.

    “We observe this to be correct and found that reperfusion was not as effective at normalizing dendritic structure as we moved to more lateral regions.”
    • Also stated in: § Irreversible loss of dendritic structure in core regions · plain
      “With two-photon imaging, we observed that the most lateral areas of the craniotomy showed the lowest potential for recovery with reperfusion.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The darker gray area, ~0.6 mm lateral to the structural border, is where dendrite tufts of layer 5 pyramidal neurons blebbed during transient MCAO, and recovered either fully or partially after reperfusion.

    “The darker gray area, which is ϳ0.6 mm lateral to the structural border, is where the dendrite tufts of the layer 5 pyramidal neurons blebbed during transient MCAO, and recovered either fully or partially after reperfusion.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductreasoning

    To reduce bias, images of dendritic panels were scored by persons who lacked information regarding treatments, time point, or medial-to-lateral orientation.

    “To reduce bias, images of dendritic panels oriented medial to lateral were cut into 250 ϫ 1024 pixel-sized sections, given random designations, and scored by persons who lacked information regarding the treatments/time point used or medial-to-lateral orientation.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Dendritic structure can be markedly disturbed during global ischemia, whereas reperfusion can lead to recovery of structure within tens of minutes.

    “Dendritic structure can be markedly disturbed during global ischemia, whereas reperfusion can lead to recovery of structure within tens of minutes (Murphy et al., 2008).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Initial studies only used an average of 7 min of occlusion or photothrombotic occlusion with undefined reperfusion, limiting their power as models of human focal stroke that typically involve occlusion of major arteries for hours.

    “initial studies only used an average of 7 min of occlusion (Murphy et al., 2008), or used photothrombotic occlusion in which reperfusion was undefined (Zhang et al., 2005), thus limiting their power as models of human focal stroke that typically involve the occlusion of major arteries for hours.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

    • cites Zhang et al., 2005

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Premisecitation

    Recent in vivo two-photon imaging experiments indicate rapid swelling and beading of dendritic structure and loss of spines within minutes of global ischemia coincident with a wave of ischemic depolarization.

    “These studies indicate rapid swelling and beading of dendritic structure and a loss of spines within minutes of global ischemia coincident with a wave of ischemic depolarization (Murphy et al., 2008).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Recovery of dendritic structure can occur after reperfusion after even 60 min of ischemia, but is likely restricted to a relatively small penumbra region with partial blood flow or oxygenation.

    “recovery of dendritic structure can occur after reperfusion after even 60 min of ischemia, but is likely restricted to a relatively small penumbra region with partial blood flow or oxygenation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Potentially salvageable dendritic structure can be within a severely hypoperfused region, as long as it is close to a normally perfused area and reperfused in a timely manner.

    “This suggests that potentially salvageable dendritic structure can be within a severely hypoperfused region, as long as it is close to a normally perfused area and reperfused in a timely manner.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    In previous work, individual blood vessels can support the structure of dendrites that were on average only 80 μm into an ischemic zone.

    “In previous work, we show that individual blood vessels can support the structure of dendrites that were on average only 80 m into an ischemic zone (Zhang and Murphy, 2007).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Zhang and Murphy, 2007

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    A limitation of the work was that reperfusion was more reliable if the suture was inserted through the CCA.

    “A limitation of our work was that reperfusion was more reliable if the suture was inserted through the CCA.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning

    In this case, the CCA was permanently occluded, leaving animals reperfused by a single CCA, with reperfusion to within ~75% of prestroke blood flow.

    “In this case, we needed to permanently occlude the CCA, leaving animals only reperfused by a single CCA (reperfused to within ϳ75% of prestroke blood flow).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationcitation

    Reperfusion of neurons within the penumbra led to an improvement in dendritic structure, arguing against reperfusion damage in this area.

    “Assessment of group data indicated that the reperfusion of neurons within the penumbra led to an improvement in dendritic structure, arguing against reperfusion damage in this area (Walder et al., 1997;Miller et al., 2006).”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Walder et al., 1997 source

      Not checked in the free run.

    • cites Miller et al., 2006

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Neurons within the core could be made to survive but may have compromised synaptic transmission because structural recovery of their apical dendritic arbors would not be expected.

    “Although neurons within the core could be made to survive, they may have compromised synaptic transmission because we would not expect structural recovery of their apical dendritic arbors.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Photothrombosis of surface arteries results in a very strong local reduction in blood flow, apparently affecting most blood vessels within the area, generating areas with little or no blood flow separated by a transition zone of only a few tens of micrometers in which blood flow begins again.

    “Photothrombosis of surface arteries results in a very strong local reduction in blood flow (Watson et al., 1985;Schaffer et al., 2006), apparently affecting most blood vessels within the area, generating areas with little or no blood flow separated by a transition zone of only a few tens of micrometers in which blood flow begins again (Zhang and Murphy, 2007).”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites Watson et al., 1985

      Not checked in the free run.

    • cites Schaffer et al., 2006

      Not checked in the free run.

    • cites Zhang and Murphy, 2007

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Recent work indicates that antiapoptotic CDK-5 inhibitors block cell death but fail to fully restore synaptic transmission and behavior after stroke.

    “Recent work indicates that this may be the case because antiapoptotic CDK-5 inhibitors block cell death but fail to fully restore synaptic transmission and behavior after stroke (Iyirhiaro et al., 2008).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Iyirhiaro et al., 2008

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    Although the ischemic core was typically outside the two-photon imaging window, a laser Doppler probe present in this area observed reperfusion.

    “Although the ischemic core was typically outside our twophoton imaging window, we did have a laser Doppler probe present in this area and observed reperfusion (data not shown).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Little recovery of core dendrites after 90 min of reperfusion implies that even if neurons could be protected from delayed cell death, their circuitry may already be irreversibly damaged.

    “Our work showing little recovery of core dendrites after 90 min of reperfusion has broad implications for neuroprotection studies because it would imply that, even if neurons could be protected from delayed cell death, their circuitry may already be irreversibly damaged.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    The MCAO model in rodents permits occlusion over hours and supports an ischemic penumbra (area with partial vascular flow) in which beneficial effects of neuroprotectants and reperfusion are thought to occur.

    “This approach parallels human ischemic stroke by permitting occlusion over hours and supporting an ischemic penumbra (area with partial vascular flow) in which the beneficial effects of neuropro-tectants and reperfusion are thought to occur (Hossmann, 2006).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Hossmann, 2006 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    Consistent with MCAO being associated with focal ischemia, heart rate was not suppressed during the occlusion period.

    “Consistent with the MCAO being associated with focal ischemia, we did not observe suppression of the heart rate during the occlusion period.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Premisecitation

    Recent in vivo two-photon imaging experiments indicate rapid swelling and beading of dendritic structure and a loss of spines within minutes of global ischemia coincident with a wave of ischemic depolarization.

    “These studies indicate rapid swelling and beading of dendritic structure and a loss of spines within minutes of global ischemia coincident with a wave of ischemic depolarization (Murphy et al., 2008).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

  • May combine two claims.

    Interpretationcitation

    The gradual darkening toward the medial portion of the laser speckle image is attributed to diffusion in microvessels, indicating higher levels of local blood flow.

    “Across the laser speckle image, a gradual darkening is apparent toward the medial portion of the image and is attributed to diffusion in microvessels (Dunn et al., 2001;Yuan et al., 2005;Sigler et al., 2008), indicating higher levels of local blood flow.”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites Dunn et al., 2001

      Not checked in the free run.

    • cites Yuan et al., 2005

      Not checked in the free run.

    • cites Sigler et al., 2008

      Not checked in the free run.

    • The authors state this as an assumption: The velocity of blood flow is proportional to the inverse of the speckle contrast.

  • May combine two claims.

    Premisecitation

    Initial two-photon studies of ischemia used only an average of 7 min of occlusion or photothrombotic occlusion with undefined reperfusion, limiting their power as models of human focal stroke.

    “Although the recovery of structure with reperfusion was remarkable, initial studies only used an average of 7 min of occlusion (Murphy et al., 2008), or used photothrombotic occlusion in which reperfusion was undefined (Zhang et al., 2005), thus limiting their power as models of human focal stroke that typically involve the occlusion of major arteries for hours.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

    • cites Zhang et al., 2005

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    Because of the time required to complete all stacks and laser speckle acquisition before reperfusion, not all areas could be imaged twice during occlusion.

    “Because of the time required to complete all stacks and laser speckle acquisition before reperfusion, we could not always image all the areas twice during occlusion.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    Ongoing small periinfarct ischemic depolarizations that could aggravate dendritic damage may go undetected because their measurement may be hampered by use of a large electrode.

    “We can- not rule out that ongoing small periinfarct ischemic depolarizations (Hossmann, 1996(Hossmann, , 2006) ) that could aggravate dendritic damage may go undetected because their measurement may be hampered by use of a large electrode.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Hossmann, 1996

      Not checked in the free run.

    • cites Hossmann, 2006 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    To reduce bias, images of dendritic panels were cut into sections, given random designations, and scored by persons who lacked information regarding treatments/time point or medial-to-lateral orientation.

    “To reduce bias, images of dendritic panels oriented medial to lateral were cut into 250 ϫ 1024 pixel-sized sections, given random designations, and scored by persons who lacked information regarding the treatments/time point used or medial-to-lateral orientation.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Interpretationnone given

    Although both the right CCA and ECA were permanently ligated, blood flowing from the contralateral CCA, and possibly ipsilateral posterior circulation, could still pass through the MCA allowing about 70% reperfusion.

    “Although both the right CCA and ECA were permanently ligated, blood flowing from the contralateral CCA, and possibly ipsilateral posterior circulation, could still pass through the MCA allowing ϳ70% reperfusion.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductreasoning

    The study was unable to quantify loss of individual dendritic spines and relied on measures of dendrite blebbing that were previously well correlated with spine loss.

    “Because of the requirement to sample relatively large areas, and to use animals with a high density of fluorescently labeled neurons (to ensure sampling of all affected areas), we were unable to quantify the loss of individual dendritic spines and relied on measures of dendrite blebbing that were previously well correlated with spine loss (Murphy et al., 2008) (see Materials and Methods).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning

    A limitation of our work was that reperfusion was more reliable if the suture was inserted through the CCA; in this case, we needed to permanently occlude the CCA, leaving animals only reperfused by a single CCA (reperfused to within ~75% of prestroke blood flow).

    “A limitation of our work was that reperfusion was more reliable if the suture was inserted through the CCA.In this case, we needed to permanently occlude the CCA, leaving animals only reperfused by a single CCA (reperfused to within ϳ75% of prestroke blood flow).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Dendrites can recover from 7 min of global ischemia and from brief interruption in local blood flow triggered by photothrombotic infarction.

    “We have shown previously in vivo that dendrites can recover from 7 min of global ischemia (Murphy et al., 2008), as well as brief interruption in local blood flow triggered by photothrombotic infarction (Zhang et al., 2005).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Murphy et al., 2008

      Not checked in the free run.

    • cites Zhang et al., 2005

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductreasoning

    There was insufficient time within the 60 min of occlusion to quantify blood flow using line scan analysis of red blood cell velocity.

    “Given that we needed to image the dendrites over typically a 0.3 ϫ 1.5 mm area and that each stack takes 5-10 min to acquire, we did not have sufficient time within the 60 min of occlusion to quantify blood flow using line scan analysis of red blood cell velocity (Kleinfeld et al., 1998).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Kleinfeld et al., 1998

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    If the ischemic core synaptic structure cannot be recovered at 3 h, it is unlikely that it would be recovered later.

    “we would argue that, if the ischemic core synaptic structure cannot be recovered at 3 h, it is unlikely that it would be recovered later.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    A limitation is that we do not image for >3 h after reperfusion.

    “A limitation is that we do not image for Ͼ3 h after reperfusion”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisereasoning

    Although the MCAO model is commonly used, it is not known how fine dendritic structure is affected during both occlusion and reperfusion in both the core and the penumbra.

    “Although the model is commonly used, it is not known how fine dendritic structure is affected during both occlusion and reperfusion in both the core and the penumbra.”
    Quote in the paperSubstantial claim
49 of 49

  • The authors state this as an assumption.

    The velocity of blood flow is proportional to the inverse of the speckle contrast.

    “In this analysis, we assume that the velocity of blood flow is proportional to the inverse of the speckle contrast as shown by Suzuki et al. (1991) and scaled over a range corresponding to maximal and minimal flow for each animal.”
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Authors
Li, P., & Murphy, T. H.
Affiliations
University of British Columbia (CA)
Corresponding author
Murphy, Timothy H.
ORCID
Venue
The Journal of Neuroscience
Publisher
Society for Neuroscience
Published
2008-11-12
Volume
28
Issue
46
Pages
11970-11979
ISSN
  • 0270-6474 (ISSN-L)
  • 1529-2401
DOI
10.1523/jneurosci.3724-08.2008
PMC
PMC6671659
OpenAlex
W2015341417
Semantic Scholar
97ea9715e17cbd06858c39d642924d6961663328
Cited by
120
References
47
Citations by year
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FWCI
5.44
Type
journal article
Language
en
Open access
Licence
Locations
  • Journal of Neuroscience (publishedVersion, cc-by-nc-sa)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Heart and Stroke Foundation of Canada
  • Heart and Stroke Foundation of British Columbia and Yukon
  • Canadian Stroke Network
  • University of British Columbia
  • Canadian Institutes of Health Research
Topics
  • Health Sciences › Medicine › Epidemiology › Acute Ischemic Stroke Management
  • Life Sciences › Neuroscience › Neurology › Neurological Disease Mechanisms and Treatments
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
Keywords
middle cerebral artery occlusion, focal cerebral ischemia, dendritic morphology, reperfusion, penumbra, ischemic core, ischemic depolarization, ischemia-reperfusion injury, layer 5 neurons, two-photon imaging
MeSH terms
Animals, Cerebrovascular Circulation, Dendrites, Disease Models, Animal, Luminescent Proteins, Male, Mice, Inbred C57BL, Mice, Transgenic, Nerve Degeneration, Reperfusion Injury, Microscopy, Confocal, Recovery of Function, Infarction, Middle Cerebral Artery, Brain Infarction, Microscopy, Fluorescence, Multiphoton, Cell Shape, Dendritic Spines, Green Fluorescent Proteins, Mice

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-07.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-07.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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