*Oxygen therapy reduces secondary hemorrhage after thrombolysis in thromboembolic cerebral ischemia Li Sun, Wei Zhou, Christian Mueller, Clemens Sommer, Sabine Heiland,Alexander T Bauer, Hugo H Marti and Roland VeltkampJournal of Cerebral Blood Flow & Metabolism 30, 16511660, 2010Impact factor5.478

*Introduction

*StrokeStroke is a brain injury. It occurs when the brain's blood supply is interrupted. Without oxygen and nutrients from blood, brain tissue dies quickly (less than 10 minutes). This causes a sudden function loss.

*Hemorrhagic stroke V.S. Ischemic stroke

*Chan P.H., 2001

* The activation and proteolytic activity of matrix metalloproteinases (MMPs), particularly MMP-9, are key factors in the proteolytic disruption of the basal lamina and tight junctions of the BBB.Hawkins and Davis, 2005; Wang et al., 2003.

* Therapy for acute ischemic stroke can be approached in two basic ways: First, by an attempt to restore or improve blood flow in an occluded vascular territory.Nighoghossian and Trouillas. 1997Therapy for acute ischemic stroke Second, via therapy directed at the cellular and metabolic targets.

*Tissue plasminogen activator (tPA)Jaspreet Kaur, et al., 2004(C)Beneficial effects of tPA are successful thrombolysis and restoration of CBF. (D) The deleterious effects come into play through the NMDA receptors, upregulation of MMPs, enhanced accumulation of PMNLs, and free radicals, which results in exacerbation of ischemic injury via excito-neurotoxicity, edema, and hemorrhage.

* HBOHBO might be more effective in stroke within the first few hours and at a pressure of 23 ATA.HBO is to increase the solubility of oxygen in plasma to a level sufficient to support tissues with minimal extraction of oxygen carried on hemoglobin.Ann K et al. 2005

*John H. Zhang et al. 2005

* Hyperbaric oxygen (HBO) and normobaric hyperoxia (NBO) attenuated BBB permeability , edema and do not increase oxidative stress after focal and global ischemia. (Mink and Dutka, 1995; Singhal et al, 2002; Veltkamp et al., 2005a)

NBO and HBO attenuates early BBB disruption and inhibition of MMP-9 mediated occludin degradation is an important mechanism for this protection. (Liu et al., 2009)

*AIMSExamine the differences in the effectiveness of oxygen therapy on postischemic BBB damage and secondary hemorrhage after thrombolysis.

*Materials and Methods

*Brain Ischemiathrombin-induced thromboemboli (TT-tMCAO)calcium-richthromboemboli (CT-tMCAO)Toomey et al ., 2002It was allowed to coagulate spontaneously for 2 hours at 37.It was exposed to a 20 mmol/L calcium solution for 1 minute.Mixed with 1.0 National Institutes of Health (NIH) units of human thrombin and 5 L of 1 mol/L CaCl2Twelve thrombi each 0.35mm in diameter and 1.5mm in length

*Spontaneously hypertensive Rat (300-350g)TT-tMCAOCT-tMCAO60 minutesair100% O2 at ambient pressure (NBO)100% O2 at 3 bar (HBO)60 minutesGelatin ZymographyMMP-9 and MMP-2Physiology parameterMABP,heart rate, blood gasHemoglobin Assayrt-PA (9mg/kg)Histologic staining 30 minutes

*1. MRI assay PWI document the perfusion status after thrombolysis and at the end of the experiment

Lesion volume was quantified in Diffusion-weighted imaging (DWI) brain sections at 2.5 and 24h after tMCAO.

tMCAO1hrAirHBONBO0hr24hr2.5 hr2hrrt-PADWI, PWIDWI, PWI

*1. MRI assaytMCAO1hrAirHBONBO0hr24hr2.5 hr2hrrt-PAT1w, T2*T1w, T2* Postischemic BBB damage was analyzedon postcontrast T1w images.

T2* MR imaging was used to detect macroscopic intracerebral hemorrhage.

*2. Spectrophotometric Hemoglobin and Gelatin Zymography Assay Spectrophotometric assay the hemoglobin content of brains.

Gelatin zymography protein expression of MMP-2 and MMP-9 at ischemic and nonischemic hemispheres.

tMCAO1hrAirHBONBO0hr24hr2hrrt-PAHemoglobin contentMMP-2 and MMP-9

*3. Histologic staining- secondary hemorrage Coronal cryosections the secondary hemorrage of brains was compared with T2* on corresponding sections.

Erythrocytic extravasations assess the severity of erythrocytic extravasations 24hr after CT-tMCAO.

tMCAO1hrAirHBONBO0hr24hr2hrrt-PAcoronal cryosectionsErythrocytic extravasations

*Results

*

*Figure 1. Hyperintense lesion volumes on magnetic resonance diffusion-weighted images at 2.5 and 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO) (mm3).TT-tMCAOCT-tMCAOMRI-DWI (Lesion volume)

* In TT-tMCAO, NBO and HBO significantly reduced lesion volume on DWI compared with air.

In CT-tMCAO, only a transient trend toward reduced lesion volume was detected in the HBO group at 2.5 hours but no differences were seen at 24 hours after tMCAO.Oxygen therapy can reduce lesion volume after thrombolysis.SUMMARY 1

*Figure 2. Volume of enhancement on postcontrast T1w magnetic resonance images 2.5 and 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO) (mm3). MRI-T1w (BBB damage)TT-tMCAOCT-tMCAO

* In TT-tMCAO, HBO significantly reduced postischemic BBB damage on T1w images.

In CT-tMCAO, HBO also significantly reduced postischemic, at 24 hours after tMCAO, whereas NBO failed to attenuate the enhancing volume on T1w Images.Hyperbaric oxygen therapy significantly reduces BBB damage after thrombolysis.SUMMARY 2

*TT-tMCAOFigure 3. Correspondence of bloodbrain barrier damage, infarct lesion, and secondary hemorrhage. T1wT2*cryosectionsBBB damageintracerebral hemorrhage2.5hr24hr24hr24hr

*Figure 4. Multimodal magnetic resonance imaging images showing the topography of the parenchymal infarct (diffusion weighted imaging (DWI) at 24 hours), bloodbrain barrier permeability (postcontrast T1w at 2.5 hours), and hemorrhage (T2* at 24 hours).24 hr2.5 hr24 hrHemorrhageBBB damageLesion volumeTT-tMCAOMRI assay

*Figure 5. Erythrocytic extravasation on trichrome-stained coronal brain sections at the level of the bregma +0.26mm (anterior commissure) 24 hours after calcium-induced thromboemboli-middle cerebral artery occlusion without recanalization. CT-tMCAO24hrIschemic striatum (score 4)Contralateral cortex without erythrocytic extravasation Ischemic cortex (score 2)Histologic staining- erythrocytic extravasation

*Figure 6. Hemoglobin spectrophotometry of perfused ischemic brain hemisphere after thromboembolic middle cerebral artery occlusion (tMCAO). Hemoglobin content

*Figure 7. Expression of matrix metalloproteinase (MMP)-2 and MMP-9 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO). TT-tMCAO24hrExpression of MMP-2 and MMP-9MMP-9MMP-2

* Thus, both NBO and HBO induced a significant reduction in macroscopic hemorrhage on T2* MR image. The area of hypointense T2* signal at 24 hours after MCAO was located within the area of intense postcontrast enhancement on T1w images at 2.5 hours after MACO. In TT-t MCAo and CT-tMCAO, HBO significantly decreased the mean hemoglobin volume. Early increase in BBB permeability appeared to indicate a risk for later secondary hemorrhage.HBO significantly reduces infarct volume, BBB permeability, hemorrhage and MMP-9 activity after thrombolysis .SUMMARY 3

*Conclusion

*Oxygen therapy can decrease infarct size and BBB damage after thromboembolic ischemia and reduce postthrombolytic intracerebral hemorrhage.

*Thank you for attention

* Oxygen therapy in combination with thrombolytic therapy only affects infarct size if recanalization is successful.

Oxygen therapy reduce size and frequency of gross parenchymal hemorrhage after thrombolysis- induced reperfusion.

HBO and NBO reduce early BBB permeability after tMCAO, which is a marker for subsequent hemorrhagic complications of thrombolysis.

Oxygen therapy improves microvascular integrity even in regions that undergo parenchymal infarction

*(cerebral thrombosis)(coagulation) (cerebral embolism)cerebral thrombosiscerebral embolism

*1. 2.

*1.(anticoagulant drugs)2.(thrombolytic drugs)3.(antiplatelet drugs)

*

* (plasmin)(fibrinolysin)(plasminogen)

* (thrombolysis agents)(plasminogen)(fibrinolytics)3~672

*Alteplase Recombinant1.(t-PA)2.

*Oxygen Content in Blood on HBOPO2, mmHgO2 content, ml/dlDissolvedHgb-bounda PO2 + 1.39 Hb SO2Dissolved O2 = a PO2 = 0.003 x 2000 [3 ATA] = 6.0 ml/dl Hb bound O2 = 1.39 Hb SO2 = 1.39 x 14 x 100% 19.7 ml/dlTotal

*Hyperbaric Oxygen TherapyHBO 1. HBO13100%2. Leach et al., 1998

***Stroke, ,,.*Stroke,.. stroke,,,.

*NFBMMPs,iNOS,BBB()*20032005MMPs ()MMP9BBB(basal lamina)(tight junction)*tPArt-PA 3 3 66 14tPA20.9/kg 90mg2.6 18% tPA90*tPAC tPA plasminogen ()plasmin ()tPADtPANMDA,MMPs,PMNLs(),,,

*2-3ATA2005Ann,

*2005Glutamate, glucosepyruvate*12009poli219952005,BBB,,32009BBBMMP-9

*tPA,BBB,BBB*TT: ,1U5micro-liter,,MCAo0.35mm1.5mmCT:,37,2,20 mmol/L 1,,MCAo0.35mm1.5mm3012,PE-50,,,MRI**MRI-DWI,2.524PWI*MRI-T1WBBB,2.524T2*~MMP2MMP9

*MCAoNBOAir,,pH**2.524MRIBBB** 1. 2. 3.BBBmarker 4.*,tPA