[The role of intravenous thrombolysis before mechanical thrombectomy in the treatment of large vessel occlusion strokes]. / A mechanikus thrombectomiát megelozo intravénás thrombolysis szerepe az akut agyi nagyérelzáródások kezelésében.

BACKGROUND AND PURPOSE: The efficacy of intravenous thrombolysis (IVT) is moderate in the proximal vascular segments of intracranial arteries, as opposed to mecha-nical thrombectomy (MT). In the management of acute ischemic stroke (AIS) caused by large vessel occlusions (LVO), IVT prior to MT is highly recommended based on the latest guidelines, but the necessity of IVT has been questioned by the latest studies of the past years. The aim of our study was to investigate and compare the efficacy and safety of direct mechanical thrombectomy (dMT) and combined therapy (CT) for patients who suffered an AIS with LVO and were treated in our department. METHODS: We investigated patients with AIS caused by LVO who were admitted up to 4.5 hours after symptom onset and underwent MT in our department between November 2017 and August 2019. Patients' data were collected in our stroke register. Patients enrolled in our study were divided into two groups depending on whether dMT or CT was used. Our primary outcome was the 30- and 90- day functional outcome measured by modified Rankin Scale (mRS). Mortality at 30- and 90- day, successful recanalization rates, and symptomatic intracranial hemorrhage were considered as secondary outcomes. RESULTS: A total of 142 patients (age: 68.3 ± 12.6 years, 53.5% female) were enrolled in our study, including 81 (57.0%) dMT cases, and 61 (43.0%) patients who received CT. The vascular risk factors and comorbidities were significantly higher in the dMT-treated group. At day 30, the rate of favorable functional outcomes was 34.7% in dMT vs. 43.6% among those who received CT (p = 0.307), by day 90 this ratio changed to 40.8% vs. 46.3% (p = 0.542). Mortality rates at day 30 were 22.2% and 23.6% (p = 0.851), and at day 90 33.8% and 25.9% (p = 0.343). The rate of effective recanalization was 94.2% for dMT-treated patients and 98.0% for CT-treated patients (p = 0.318). Symptomatic intracranial hemorrhage was detected in 2.5% of dMT-treated patients and 3.4% of CT-treated group (p = 0.757). CONCLUSION: Our results suggest that CT is associated with a moderately better outcome compared to dMT. IVT prior to MT did not increase the risk of symptomatic intracranial hemorrhages.

Increased level of LIGHT/TNFSF14 is associated with survival in aneurysmal subarachnoid hemorrhage.

OBJECTIVES: Multiple cytokines have been implicated in aneurysmal subarachnoid hemorrhage (aSAH), but tumor necrosis factor superfamily 14 (LIGHT/TNFSF14) and oncostatin-M (OSM) have not been previously explored. AIMS OF THE STUDY: The primary objective of this study was to examine the relationship between TNFSF14 and OSM levels and survival. Our secondary goal was to investigate a potential association between these markers and the incidence of delayed cerebral ischemia (DCI). MATERIALS & METHODS: We consecutively recruited 60 patients with a clinical diagnosis of aSAH. LIGHT/TNFSF14 and OSM serum concentrations were determined by ELISA. The primary endpoint was survival at Day 30, while development of DCI was assessed as secondary outcome. RESULTS: Patients had significantly higher levels of both markers than the control group (median of LIGHT: 18.1 pg/ml vs. 7 pg/ml; p = 0.01; median of OSM: 10.3 pg/ml vs. 2.8 pg/ml, p < 0.001). Significantly lower serum level of LIGHT/TNFSF14 was found in nonsurviving patients (n = 9) compared with survivors (n = 51; p = 0.011). Based on ROC analysis, serum LIGHT/TNFSF14 with a cutoff value of >7.95 pg/ml predicted 30-day survival with a sensitivity of 71% and specificity of 78% (Area: 0.763; 95% CI: 0.604-0.921, p = 0.013). In addition, it was also a predictor of DCI with a sensitivity of 72.7% and a specificity of 62.5% (AUC: 0.702; 95% CI: 0.555-0.849, p = 0.018). Based on binary logistic regression analysis, LIGHT/TNFSF14 was found to be independently associated with 30-day mortality, but not with DCI. CONCLUSION: In this cohort, a higher serum level of LIGHT/TNFSF14 was associated with increased survival of patients with aSAH.

Fatty Acid-Binding Protein 3 and CXC-Chemokine Ligand 16 are Associated with Unfavorable Outcome in Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is associated with activation of the inflammatory cascade contributing to unfavorable outcome and secondary complications, such as delayed cerebral ischemia (DCI). Both fatty acid-binding protein 3 (FABP3) and CXC-chemokine ligand 16 (CXCL-16) have been linked to vascular inflammation and cellular death. The authors aimed to assess the 30-day prognostic value of serum levels of FABP3 and CXCL-16 and explore their associations with DCI in aSAH patients. METHODS: A total of 60 patients with aSAH were prospectively enrolled. Sampling for markers was done at 24 hours after the index event. FABP3 and CXCL-16 serum concentrations were determined by MilliPlex multiplex immunoassay method. The primary endpoint was unfavorable outcome at Day 30 based on the modified Rankin Scale. RESULTS: Both FABP3 and CXCL-16 levels were significantly elevated in patients with unfavorable outcome compared to those with favorable outcome after aSAH (FABP3: 2133 pg/mL, IQR: 1053-4567 vs. 3773, 3295-13116; p<0.003 and CXCL-16: 384 pg/mL, 313-502 vs. 498, 456-62, p<0.001). The area under the curve (AUC) for serum CXCL-16 levels as a predictor of unfavorable outcome at Day 30 was 0.747 (95% CI =0.622-0.871; p<0.001). Based on binary logistic regression analysis, serum CXCL-16 with a cut-off level >446.7 ng/L independently predicted Day 30 unfavorable outcome with a sensitivity of 81% and a specificity of 62%. Neither CXCL-16 nor FABP3 showed a significant correlation with DCI. CONCLUSION: Early FABP3 and CXCL-16 levels are significantly associated with poor 30-day outcome in patients with aSAH.

Risk analysis of post-procedural intracranial hemorrhage based on STAY ALIVE Acute Stroke Registry.

BACKGROUND: Intracranial hemorrhages (ICH) are classified as symptomatic or asymptomatic according to the presence of clinical deterioration. Here, we aimed to find predictive factors of symptomatic intracranial bleeding in a registry-based stroke research. METHODS: Data of consecutive patients with acute ischemic stroke (AIS) were extracted from the prospective STAY ALIVE stroke registry. Analysis of the total population and treatment sugroups such as endovascular thrombectomy (EVT), intravenous thrombolysis (IVT), or their combination (IVT+EVT) were also done. Outcome measures were ICH, 30- and 90-day clinical outcome based on the modified Rankin Scale (mRS:0-2 as favorable outcome). The hemorrhage was captured by a non-enhanced CT of the skull within 24 h after procedure. RESULTS: A total of 355 patients (mean age: 68±11; female N=177 (49.9%); EVT n=131 (36.9%); IVT n=157 (44.2%); IVT+EVT n=67 (18.9%) were included in the analysis. The total number of ICH was 47 (13%), symptomatic (sICH) 12 (3.4%) and asymptomatic (aICH) 35 (9.9%) in the whole population. NIHSS ≥15.5 at 24 post stroke hours predicted sICH with a sensitivity of 100% and a specificity of 92% (p<0.001). Furthermore, lower age, good collateral circulation on initial CT angiography and lower NIHSS score measured at 24 h independently associated with a favorable 90-day outcome, whereas baseline NIHSS and ASPECT score were not. CONCLUSION: Although partial recanalization, ASPECT< 6, and poor collaterals were significantly associated with sICH, the only independent predictor was NIHSS ≥15.5 at 24 post stroke hours. This suggests a careful evaluation of patients with worsening NIHSS despite an adequate therapy.

Treatment of In-stent Restenosis of the Internal Carotid Artery Using Drug-eluting Balloons.

PURPOSE: In-stent restenosis (ISR) following internal carotid artery (ICA) stenting is relatively common with an estimated incidence of 5%. Treatment options include repeat angioplasty with conventional or drug-eluting balloons (DEB), repeat stent angioplasty and surgical intervention. Application of DEB in ISR of the coronary and peripheral arteries is an established method; however, data on DEB treatment of ICA ISR are sparse. In this work, results from a retrospective cohort of 45 patients harboring 46 ICA ISR lesions treated with DEB angioplasty are presented. METHODS: Clinical, procedural and imaging data from DEB angioplasty treatment of 46 high-grade ICA ISR lesions in 45 patients, performed between 2013 and 2021 were collected. A single type of DEB (Elutax, Aachen Resonance, Aachen, Germany) was used in all procedures. Imaging follow-up was performed by regular Doppler ultrasound (DUS), verified by computed tomography angiography (CTA) in cases suspicious for a recurrent ISR. RESULTS: Technical success was 100%. Intraprocedural and postprocedural complications were not encountered. Clinical follow-up was obtained in all patients. Recurrent stroke in the affected territory was not encountered. A recurrent ISR following DEB treatment was confirmed by DUS and CTA in 4/46 (8.7%) of the lesions and were retreated with DEB. A third recurrent ISR occurred in a single case (2%) and following a second DEB retreatment there were no signs of a fourth recurrence after 36 months follow-up. CONCLUSION: The use of DEB angioplasty is a safe and effective treatment of ICA ISR lesions, yielding significantly better results compared to other modalities. Randomized multicenter studies are warranted.

Cerebral arterial fenestrations: a common phenomenon in unexplained subarachnoid haemorrhage.

BACKGROUND: Fenestrations of intracranial arteries are variants resulting from incomplete fusion of vessels during development with unknown clinical significance. They are best visualised with 3D rotational angiography (3DRA). OBJECTIVE: In a prospective consecutive series of patients with suspected aneurysms, 3DRA was performed to identify not only the potential bleeding source but also to assess the frequency and location of any fenestrations of intracranial arteries. METHODS: In 287 consecutive patients with possible intracranial aneurysms (accidental discovery or previous history of SAH), 3DRAs were prospectively performed, and the location of subarachnoid haemorrhage was assessed by CT. RESULTS: Of 174 patients presenting with SAH, 153 had saccular aneurysms, and in 21 cases (12.1 %), no source of bleeding was found. In 20 of these 21 patients with "unexplained SAH" (95.2 %) an arterial fenestration was detected in the neighbourhood of the clot. The incidence of fenestration in the 153 aneurysmal SAH patients was 22.9 %, and it was 23.3 % in 266 patients with intracranial aneurysms (113 accidental and 153 ruptured). CONCLUSIONS: Arterial fenestration was detected in 22.9 % of ruptured cerebral aneurysms, in contrast with 95.2 % in patients with unexplained SAH, the difference being statisctically significant (p < 0.01). Fenestration is a developmental defect, a structural wall weakness possibly making the vessel prone to rupture. Its incidence of nearly 100 % may suggest a connection with idiopathic SAH. The presented data indicate that arterial fenestrations are generally overlooked, and they can be considered as one of the candidates for the source of idiopathic SAH.

Serum Periostin May Help to Identify Patients with Poor Collaterals in the Hyperacute Phase of Ischemic Stroke.

Background: Periostin is a glycoprotein that mediates cell functions in the extracellular matrix and appears to be a promising biomarker in neurological damage, such as ischemic stroke (IS). We aimed to measure serum periostin levels in the hyperacute phase of ischemic stroke to explore its predictive power in identification of patients with poor collaterals (ASPECT < 6). Methods: We prospectively enrolled 122 patients with acute ischemic stroke within the first 6 h after onset. The early ischemic changes were evaluated by calculating ASPECT score on admission using a native CT scan. An unfavorable outcome was defined as the modified Rankin Scale (mRS) > 2 at 90 days follow-up. Blood samples were collected on admission immediately after CT scan and periostin serum concentrations were determined by ELISA. Results: The admission concentration of serum periostin was significantly higher in patients with unfavorable outcome than in patients with favorable outcome (615 ng/L, IQR: 443−1070 vs. 390 ng/L, 260−563, p < 0.001). In a binary logistic regression model, serum periostin level was a significant predictor for ASPECT < 6 status on admission, within 6 h after stroke onset (OR, 5.911; CI, 0.990−0.999; p = 0.015). Conclusion: Admission periostin levels can help to identify patients who are not suitable for neurointervention, especially if advanced neuroimaging is not available.

General Anesthesia-Related Drop in Diastolic Blood Pressure May Impact the Long-Term Outcome in Stroke Patients Undergoing Thrombectomy.

Background: Several factors affect the efficacy of endovascular thrombectomy (EVT); however, the anesthesia-related factors have not been fully explored. We aimed to identify independent predictors of outcome by analyzing procedural factors based on a multicentric stroke registry. Methods: Data of consecutive patients with acute ischemic stroke (AIS) were extracted from the prospective STAY ALIVE stroke registry. Demographic, clinical, and periprocedural factors including hemodynamic values were analyzed in patients undergoing thrombectomy with either general anesthesia (GA) or conscious sedation (CS). Independent predictors of outcome both at 30 and 90 days based on the modified Rankin Scale (mRS: 0−2 as favorable outcome) were also explored. Results: A total of 199 patients (GA: 76 (38%) vs. CS: 117 (59%); in addition, six patients were converted from CS to GA) were included. The minimum value of systolic, diastolic, and mean arterial pressure was significantly lower in the GA compared to the CS group, and GA was associated with a longer onset to EVT time and a higher drop in all hemodynamic variables (all, p < 0.001). A higher drop in diastolic blood pressure (DBP) was even independently associated with a poor 90-day outcome (p = 0.024). Conclusion: A GA-related drop in DBP may independently predict a poor long-term outcome in stroke patients undergoing thrombectomy.

Endovascular Recanalization of Tandem Internal Carotid Occlusions Using the Balloon-assisted Tracking Technique.

PURPOSE: Tandem occlusive lesions are responsible for up to 20% of acute ischemic stroke cases and are associated with poor prognosis if complete recanalization cannot be achieved. Endovascular recanalization might be challenging due to difficulties in the safe passage of the occluded plaque at the origin of the internal carotid artery (ICA). The balloon-assisted tracking technique (BAT), where a partially deflated balloon is exposed out of the catheter tip to facilitate its passage through stenosed or spastic arterial segments was introduced by interventional cardiologists and the applicability of the technique has been recently proposed in the field of neurointervention as well. Here we describe our experience using the BAT technique in the endovascular recanalization of tandem occlusive lesions. METHODS: Procedures were performed from June 2013 to December 2020 in a single center. Baseline clinical and imaging data, procedural and follow-up details and clinical outcomes were retrospectively collected. RESULTS: In this study 107 patients, median age 66 years, median admission NIHSS 14 and median ASPECTS 8 were included. Successful recanalization of the ICA using the BAT technique was achieved in 100 (93%) and successful intracranial revascularization in 88 (82%) patients. There were no complications attributable to the BAT technique. Intraprocedural complications occurred in 9 (8%) patients. Emergent stenting was performed in 40 (37%) at the end of the procedure. Postprocedural adverse events (intracerebral hemorrhage [ICH], malignant infarction) occurred in 6 (5%) patients. Good clinical outcome at 3 months (modified Rankin scale [mRS] 0-2) was 54 (50%) and mortality 26 (24%). Delayed stent placement during follow-up occurred in 21 cases. CONCLUSION: Application of BAT technique in tandem occlusions appears feasible, safe, and efficient. Further evaluation of this technique is awaited.

Teleradiology-based stroke network in Western and Southern Transdanubia in Hungary / Stroke-ellátást támogató teleradiológiai hálózat a Nyugat- és Dél-Dunántúlon.

Összefoglaló. Bevezetés: A stroke kezelésének lehetoségei az utóbbi években jelentosen megváltoztak: a thrombolysis után bevezetésre került a mechanikus thrombectomia, és a terápiás idoablak is jelentosen kitágult az utóbbi évek nagy multicentrikus tanulmányai alapján. Ezek a lehetoségek új igényeket fogalmaztak meg a képalkotó diagnosztikával szemben: az ischaemia okozta morfológiai elváltozások mellett az artériás és a kollaterális rendszer állapotát, valamint bizonyos esetekben az agy szöveti perfúzióját is szükséges meghatározni. Ezeket a komplex kiértékelési feladatokat ma már mesterségesintelligencia-algoritmusok támogathatják, melyek a kiértékelést pár perc alatt elvégezve segítenek a terápiás döntés kialakításában. Célkituzés: A Dél- és a Nyugat-dunántúli régióban hat intézmény részvételével egy dedikált stroke teleradiológiai hálózat kialakítása. Módszer: A stroke-CT-kiértékelo szoftver és a képkommunikáció integrációja, a vizsgálati protokollok technikai paramétereinek egységesítése, a kiértékelési eredmények teleradiológiai megjelenítése valósult meg a hálózat kialakítása során. Eredmények: A hálózat egységesítette nemcsak a stroke-CT-protokollok beállításait, de beutalási és értékelési szempontjait is. A stroke-CT-kiértékelések és a mechanikus thrombectomiák száma is emelkedett az elmúlt egy évben. Következtetés: A dedikált teleradiológiai stroke-hálózat segítségével optimalizálni kívánjuk a régió stroke-ellátását: egyrészt lehetoleg ne maradjanak ellátatlanul a thrombectomiából valószínuleg profitáló betegek, másrészt ne terheljük az ellátórendszert olyan esetekkel, melyekrol a teljes dokumentáció ismeretében derül ki, hogy nem javasolt a beavatkozás. Orv Hetil. 2021; 162(17): 668-675. INTRODUCTION: The possibilities of cerebral stroke management have changed substantially during the last few years. Following a few multicentric studies, mechanical thrombectomy became an established method besides thrombolysis. In addition, the therapeutic window for both methods is much wider now than before. These changes described above demanded more information of CT morphological changes due to ischemia, but the condition and functionality of the arterial and collateral system, and occasionally tissue perfusion performance should also be characterized. Recently, evaluation of different computer tomographic (CT) measurements can be done using artificial intelligence based methods, which perform data analysis in a few minutes. OBJECTIVE: To establish a dedicated stroke teleradiology network with artificial intelligence based image analysis in Western and Southern Transdanubia in Hungary that involves six partner institutes. METHOD: Integration of automated image analysis with teleradiology software was established, and the technical parameters of examination protocols were unified. Results of stroke CT image analysis became accessible through the teleradiology network. RESULTS: The daily use of integrated central image analysis and image communication had a positive impact on referrals and therapeutic evaluation of stroke cases. The number of image processing and mechanical thrombectomy increased during the last year. CONCLUSION: With the help of the dedicated teleradiology stroke network, we want to optimize the stroke care in the region: on the one hand, patients who are likely to benefit from thrombectomy should not be left unattended, on the other, the health care system should not be burdened with cases, when intervention is not recommended having the complete clinical data accessed. Orv Hetil. 2021; 162(17): 668-675.

Comparing Endovascular Treatment Methods in Acute Ischemic Stroke Due to Tandem Occlusion Focusing on Clinical Aspects.

INTRODUCTION: Acute ischemic strokes (AIS) due to tandem occlusion (TO) of intracranial anterior large vessel and concomitant extracranial internal carotid artery (EICA) are represent in 15-20% of all ischemic strokes. The endovascular treatment (EVT) strategy for those patients is still unclear. Although the intracranial mechanical thrombectomy (MT) is considered as a standard treatment approach, the EICA lesion stent necessity remains a matter of debate. We sought to assess the efficacy and safety of EVT in tandem lesions, particularly the EICA stenting management. METHODS: We retrospectively analyzed all patients with anterior circulation stroke associated with EICA lesion and receiving EVT in the three participated stroke centers between November 2017 and December 2020. Patients' data were collected from our prospective stroke registry (STAY ALIVE). Patients enrolled in our study were divided into two groups depending on whether acute carotid stenting (ACS) or balloon angioplasty only (BAO) technique was used. Our primary outcome was the 90-day functional outcome assessed by modified Rankin scale (mRS). Mortality at 90 days and symptomatic intracranial hemorrhage (sICH) were considered as secondary outcomes. RESULTS: A total of 101 patients (age: 67 ± 10 years, 38.6% female) were enrolled in our study, including 29 (28.3%) BAO cases, and 72 (71.3%) patients treated with ACS. Patients in the BAO group were slightly older (70 ± 9 years vs. 66 ± 10 years, p = 0.054), and had higher prevalence of comorbidities such as hypertension (100.0% vs. 59.4%, p < 0.001). There was no significant difference in favorable outcomes (51.7% vs. 54.4%, p = 0.808) between the groups. However, we observed a trend towards higher rates of sICH (8.3% vs. 3.4%, p = 0.382) and 90-day mortality (23.5% vs. 13.8%, p = 0.278) with significantly higher frequency of distal embolization (39.1% vs. 17.9%, p = 0.043) in patients with ACS. In the overall population age (p = 0.013), atrial fibrillation (AF) (p = 0.008), National Institutes of Health Stroke Scale (NIHSS) baseline (p = 0.029), and successful recanalization (p = 0.023) were associated with favorable outcome. CONCLUSION: Endovascular approach of EICA in addition to MT was safe and effective in tandem occlusion of anterior circulation. Furthermore, our results suggest that balloon angioplasty technique without acute stenting shows a comparable favorable outcome rate to ACS with moderately less hemorrhagic events and mortality rates.

Contribution of poly(ADP-ribose) polymerase to postischemic blood-brain barrier damage in rats.

The nuclear enzyme poly(ADP-ribose) polymerase (PARP) is activated by oxidative stress and plays a significant role in postischemic brain injury. We assessed the contribution of PARP activation to the blood-brain barrier (BBB) disruption and edema formation after ischemia-reperfusion. In male Wistar rats, global cerebral ischemia was achieved by occluding the carotid arteries and lowering arterial blood pressure for 20 mins. The animals were treated with saline or with the PARP inhibitor N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-N, N-dimethylacetamide.HCl (PJ34); (10 mg/kg, i.v.) before ischemia. After 40 mins, 24, and 48 h of reperfusion, the permeability of the cortical BBB was determined after Evans Blue (EB) and Na-fluorescein (NaF) administration. The water content of the brain was also measured. The permeability of the BBB for EB increased after ischemia-reperfusion compared with the nonischemic animals after 24 and 48 h reperfusion but PARP inhibition attenuated this increase at 48 h (nonischemic: 170+/-9, saline: 760+/-95, PJ34: 472+/-61 ng/mg tissue). The extravasation of NaF showed similar changes and PJ34 post-treatment attenuated the permeability increase even at 24 h. PARP inhibition decreased the brain edema seen at 48 h. Because PARP has proinflammatory properties, the neutrophil infiltration of the cortex was determined, which showed lower values after PJ34 treatment. Furthermore, PJ34 treatment decreased the loss of the tight junction protein occludin at 24 and 48 h. The inhibition of PARP activity accompanied by reduced post-ischemic BBB disturbance and decreased edema formation suggests a significant role of this enzyme in the development of cerebral vascular malfunction

Influence of the heme-oxygenase pathway on cerebrocortical blood flow.

Heme-oxygenase (HO)-derived carbon monoxide (CO) is generated in the cardiovascular and in the central nervous systems. Endogenous CO exerts direct vascular effects and has also been shown to inhibit nitric oxide synthase (NOS). In the current study, the heme-oxygenase blockade [zinc deuteroporphyrin 2,4-bis glycol (ZnDPBG), 45 micromol/kg intraperitoneally] decreased cerebral CO production and increased cerebrocortical blood flow (CBF) in anesthetized rats. This latter effect was abrogated by the NOS blockade (50 mg/kg L-NAME intravenously). Furthermore, inhibition of CO production had no effect on stepwise hypoxia/hypercapnia-stimulated increases in CBF. Our results indicate that endogenous CO reduces the resting CBF via inhibition of NOS but fails to influence the CBF response to hypoxia and hypercapnia in adult rats.

Blood-brain barrier changes during compensated and decompensated hemorrhagic shock.

Dysfunction of the blood-brain barrier (BBB) can be associated with a large number of central nervous system and systemic disorders. The aim of the present study was to determine BBB changes during different phases of hemorrhagic shock. The experiments were carried out on male Wistar rats anaesthetized with urethane. To produce compensated or decompensated hemorrhagic shock, mean arterial pressure was decreased from the normotensive control values to 40 mmHg by a standardized method of blood withdrawal from the femoral artery. Cerebral blood flow changes were followed by laser-Doppler flowmetry, and arterial blood gas values were monitored over the whole procedure. Cortical blood flow was significantly reduced in compensated and in decompensated hemorrhagic shock compared with the normotensive rats. As the shock shifted to the decompensated phase, the blood flow reduction was more pronounced. BBB permeability studies using sodium fluorescein (molecular weight of 376) and Evan's Blue albumin (molecular weight of 67,000) have revealed a significant increase of the BBB permeability for sodium fluorescein in the decompensated stage of hemorrhagic shock. Western blot analysis of brain capillaries showed that the expression of the transmembrane tight junction protein occludin was reduced in response to hemorrhagic shock, and the decrease of occludin was more pronounced in the decompensated phase. A similar expression pattern was shown by the transmembrane adherens junction protein cadherin as well. Our results suggest that the decompensated phase of hemorrhagic shock is associated with disturbances of the BBB, which may be explained by the dysfunction of interendothelial junctions caused by decreased occludin and cadherin levels.

Diazoxide preconditioning attenuates global cerebral ischemia-induced blood-brain barrier permeability.

Brain edema formation due to blood-brain barrier (BBB) disruption is a major consequence of cerebral ischemia. Previously, we demonstrated that targeting mitochondrial ATP-sensitive potassium channels (mitoK(ATP)) protects neuronal tissues in vivo and in vitro, however, the effects of mitoK(ATP) openers on cerebral endothelial cells and on BBB functions have never been examined. We investigated the effects of mitoK(ATP) channel opener diazoxide on BBB functions during ischemia/reperfusion injury (I/R). Rats were treated with 6, 20 or 40 mg/kg diazoxide ip for 3 days then exposed to global cerebral ischemia for 30 min. BBB permeability was assessed by administering Evan's-blue (EB) and Na-fluorescein (NaF) at the beginning of the 30 min reperfusion. I/R increased BBB permeability for the large molecular weight EB (ng/mg) in the cortex (control: 146 +/- 12, n = 7; I/R: 1049 +/- 152, n = 11) which was significantly attenuated in diazoxide-treated rats (575 +/- 99, n = 9; 582 +/- 104, n = 8; 20 and 40 mg/kg doses). Diazoxide pretreatment also significantly inhibited the extravasation of the low molecular weight NaF. Edema formation in the cortex was also decreased after diazoxide pretreatment. In cultured cerebral endothelial cells, diazoxide depolarized the mitochondrial membrane, suggesting a direct diazoxide effect on the endothelial mitochondria. Our results demonstrate that preconditioning of cerebral endothelium with diazoxide protects the BBB against ischemic stress.

Hypersensitivity to thromboxane receptor mediated cerebral vasomotion and CBF oscillations during acute NO-deficiency in rats.

BACKGROUND: Low frequency (4-12 cpm) spontaneous fluctuations of the cerebrovascular tone (vasomotion) and oscillations of the cerebral blood flow (CBF) have been reported in diseases associated with endothelial dysfunction. Since endothelium-derived nitric oxide (NO) suppresses constitutively the release and vascular effects of thromboxane A(2) (TXA(2)), NO-deficiency is often associated with activation of thromboxane receptors (TP). In the present study we hypothesized that in the absence of NO, overactivation of the TP-receptor mediated cerebrovascular signaling pathway contributes to the development of vasomotion and CBF oscillations. METHODOLOGY/PRINCIPAL FINDINGS: Effects of pharmacological modulation of TP-receptor activation and its downstream signaling pathway have been investigated on CBF oscillations (measured by laser-Doppler flowmetry in anesthetized rats) and vasomotion (measured by isometric tension recording in isolated rat middle cerebral arteries, MCAs) both under physiological conditions and after acute inhibition of NO synthesis. Administration of the TP-receptor agonist U-46619 (1 µg/kg i.v.) to control animals failed to induce any changes of the systemic or cerebral circulatory parameters. Inhibition of the NO synthesis by nitro-L-arginine methyl ester (L-NAME, 100 mg/kg i.v.) resulted in increased mean arterial blood pressure and a decreased CBF accompanied by appearance of CBF-oscillations with a dominant frequency of 148±2 mHz. U-46619 significantly augmented the CBF-oscillations induced by L-NAME while inhibition of endogenous TXA(2) synthesis by ozagrel (10 mg/kg i.v.) attenuated it. In isolated MCAs U-46619 in a concentration of 100 nM, which induced weak and stable contraction under physiological conditions, evoked sustained vasomotion in the absence of NO, which effect could be completely reversed by inhibition of Rho-kinase by 10 µM Y-27632. CONCLUSION/SIGNIFICANCE: These results suggest that hypersensitivity of the TP-receptor-Rho-kinase signaling pathway contributes to the development of low frequency cerebral vasomotion which may propagate to vasospasm in pathophysiological states associated with NO-deficiency.

Carbon monoxide-prostaglandin E2 interaction in the hypothalamic circulation.

The heme oxygenase (HO)-carbon monoxide pathway was earlier shown to increase hypothalamic blood flow after inhibition of nitric oxide synthesis in rats. We hypothesized that this effect is mediated by prostaglandin E2 (PGE2). Inhibition of constitutive HO activity decreased cerebral PGE2 production and simultaneously increased hypothalamic nitric oxide synthase (NOS) activity without changing hypothalamic blood flow. Furthermore, HO blockade induced cyclooxygenase-dependent decrease and NOS-mediated increase of the hypothalamic blood flow after inhibition of NOS and cyclooxygenase, respectively. Therefore, constitutive carbon monoxide release seems to have two indirect effects on the hypothalamic circulation: vasodilation mediated by PGE2 and vasoconstriction as a result of NOS inhibition.

Neuronal preconditioning with the antianginal drug, bepridil.

It has recently been shown that the antianginal drug bepridil (BEP) activates mitochondrial ATP-sensitive potassium (mitoK(ATP)) channels and thus confers cardioprotection. Our aim was to investigate whether BEP could induce preconditioning in cultured rat cortical neurons. Although BEP depolarized isolated and in situ mitochondria and increased reactive oxygen species generation, no acute protection was observed. However, a 3-day BEP-treatment elicited dose-dependent delayed neuroprotection against 180 min of oxygen-glucose deprivation (cell viability: untreated, 52.5 +/- 0.85%; BEP 1 micromol/L, 59.6 +/- 1.53%*; BEP 2.5 micromol/L, 71.9 +/- 1.23%*; BEP 5 micromol/L, 95.3 +/- 0.89%*; mean +/- SEM; *p < 0.05 vs. untreated) and 60 min of glutamate excitotoxicity (200 micromol/L; cell viability: untreated, 54.1 +/- 0.69%; BEP 1 micromol/L, 61.2 +/- 1.19%*; BEP 2.5 micromol/L, 78.1 +/- 1.67%*; BEP 5 micromol/L, 91.2 +/- 1.20%*; mean +/- SEM; *p < 0.05 vs. untreated), and inhibited the reactive oxygen species surge upon glutamate exposure. The protection was antagonized with co-application of the superoxide dismutase mimetic M40401, but not with reduced glutathione, catalase, or with the mitoK(ATP) blocker 5-hydroxydecanoate. Furthermore, BEP treatment resulted in increased levels of phosphorylated protein kinase C, manganese-dependent superoxide dismutase, glutathione peroxidase, and Bcl-2. Our results indicate that BEP induces delayed neuronal preconditioning which is dependent on superoxide generation but perhaps not on direct mitoK(ATP) activation.

Transient glucose and amino acid deprivation induces delayed preconditioning in cultured rat cortical neurons.

Several studies have demonstrated that glucose deprivation, combined either with anoxia or with the inhibition of oxidative phosphorylation, leads to the development of ischemic tolerance in neurons. The aim of our experiments was to investigate whether similar effects could be achieved by transient energy deprivation without either anoxia or the inhibition of the electron transfer chain. Preconditioning was carried out by incubating primary rat cortical neuronal cultures for 3, 6 or 9 h in a glucose- and amino acid-free balanced salt solution supplemented with B27 in normoxic conditions. After 24 h, neuronal cultures were exposed to oxygen-glucose deprivation, glutamate or hydrogen peroxide. Cell viability was measured 24 h after the lethal insults. Potential mechanisms that can influence free radical production were also examined. Energy deprivation protected neuronal cells against lethal stimuli (e.g. cell survival after oxygen-glucose deprivation was 33.1 +/- 0.52% in the untreated group and 80.1 +/- 1.27% in the 9-h energy deprivation group), reduced mitochondrial membrane potential, decreased free radical formation, attenuated the intracellular free calcium surge upon glutamate receptor stimulation, and resulted in an elevated level of GSH. Our findings show that transient energy deprivation induces delayed preconditioning and prevents oxidative injuries and neuronal cell death.