Long-term Reperfusion Research Articles

Choriocapillaris Reperfusion in Resolved Chronic Central Serous Chorioretinopathy Treated with Eplerenone: Long-Term Effects on the Fellow Eye.

The aim of this work is to utilize swept-source optical coherence tomography angiography (SS-OCTA) to assess the long-term changes in the choroidal and choriocapillaris (CC) layers of the fellow unaffected eye of patients with unilateral resolved chronic central serous chorioretinopathy (cCSC) following treatment with continuous oral eplerenone (EPL). The study included 35 patients with cCSC and subretinal fluid (SRF) in one eye. SS-OCTA imaging was performed on the fellow cCSC eyes at baseline, 6months, and 12months during eplerenone therapy. CC OCT angiography was analyzed to determine the percentage of choriocapillaris flow deficits (FD%), the number of flow deficits (FDn), and the average area of flow deficits (FDa). The results demonstrated significant changes in CC flow deficits from baseline to follow-up visits. Specifically, there was a significant decrease in FD% from 28.9 ± 2.2% at baseline to 26.4 ± 1.9% at 6months (p = 0.023), and further to 24.9 ± 1.7% at 12months (p = 0.001). Additionally, the FD area gradually contracted over the follow-up period (p < 0.05). Conversely, there was a significant increase in the number of flow deficits compared to baseline (p < 0.05). No statistically significant changes were observed in best-corrected visual acuity (BCVA) at the follow-up visits (p > 0.05). The findings of this study demonstrated long-term reperfusion of the choriocapillaris in unaffected fellow cCSC eyes during continuous oral eplerenone therapy. The beneficial effects of eplerenone therapy were observed after 6months and maintained at 1year. These results suggest that specific mineralocorticoid receptor (MR) antagonists may be effective in promoting choriocapillaris recovery in the unaffected eyes of patients with cCSC.

Global cerebral ischemia followed by long-term reperfusion promotes neurodegeneration, oxidative stress, and inflammation in the small intestine in Wistar rats

AimsBrain ischemia and reperfusion may occur in several clinical conditions that have high rates of mortality and disability, compromising an individual’s quality of life. Brain injury can affect organs beyond the brain, such as the gastrointestinal tract. The present study investigated the effects of cerebral ischemia on the ileum and jejunum during a chronic reperfusion period by examining oxidative stress, inflammatory parameters, and the myenteric plexus in Wistar rats. Main methodsIschemia was induced by the four-vessel occlusion model for 15 min with 52 days of reperfusion. Oxidative stress and inflammatory markers were evaluated using biochemical techniques. Gastrointestinal transit time was evaluated, and immunofluorescence techniques were used to examine morpho-quantitative aspects of myenteric neurons. Key findingsBrain ischemia and reperfusion promoted inflammation, characterized by increases in myeloperoxidase and N-acetylglycosaminidase activity, oxidative stress, and lipid hydroperoxides, decreases in superoxide dismutase and catalase activity, a decrease in levels of reduced glutathione, neurodegeneration in the gut, and slow gastrointestinal transit. SignificanceChronic ischemia and reperfusion promoted a slow gastrointestinal transit time, oxidative stress, and inflammation and neurodegeneration in the small intestine in rats. These findings indicate that the use of antioxidant and antiinflammatory molecules even after a long period of reperfusion may be useful to alleviate the consequences of this pathology.

INTRANASAL INSULIN DECREASES AUTOPHAGIC AND APOPTOTIC DEATH OF NEURONS IN THE RAT HIPPOCAMPAL C1 REGION AND FRONTAL CORTEX UNDER FOREBRAIN ISCHEMIA–REPERFUSION

The development of approaches to therapy of ischemic brain injuries requires a better insight into the mechanisms that regulate both apoptotic and autophagic death of neurons. Under a strong ischemic (or other pathological) exposure, neurons can die from the activation of both apoptosis and autophagy. This work was aimed to assess the contribution of autophagy and apoptosis activation to neuronal cell death in the hippocampal CA1 region and frontal cortex using the rat two-vessel occlusion/hypotension model of global forebrain ischemia with subsequent long-term reperfusion, as well as to study the ability of intranasal insulin to prevent autophagic and apoptotic death of neurons. The inhibitors of autophagy (3-methyladenine), apoptosis (Ac-DEVD-CHO), or phosphate buffer (for control) were administered to rats intracerebroventricularly before ischemia and reperfusion. To count viable neurons, brain sections were stained with a Nissl stain. During ischemia–reperfusion, the number of viable neurons in the hippocampal CA1 region decreased by 58.3 ± 1.5% of their count in sham-operated rats (control taken as 100%). The administration of autophagy or apoptosis inhibitors increased the number of viable neurons in the hippocampal CA1 region from 58.3 ± 1.5% to 90.4 ± 2.2% (p 0.001) and 71.6 ± 1.8% (p 0.001) vs. control, respectively. Intranasal insulin administration at a dose of 0.5 IU (before ischemia and at a daily basis for 7 days during reperfusion) normalized the number of viable neurons in the hippocampal CA1 region up to 100.2 ± 1.95% vs. control. In the frontal cortex, the viability of neurons also decreased under ischemia–reperfusion, while the number of viable neurons increased after the administration of autophagy or apoptosis inhibitors, and even to a greater extent after intranasal insulin administration. The main difference was a lower sensitivity of cortical vs. hippocampal neurons to ischemia–reperfusion. These data indicate that intranasal insulin is able to decrease the death of brain neurons caused by the activation of autophagy and apoptosis due to ischemia–reperfusion.

Evaluation of the Effectiveness of Post-Stroke Metformin Treatment Using Permanent Middle Cerebral Artery Occlusion in Rats.

Stroke is the second leading cause of death worldwide. Treatment options for ischemic stroke are limited, and the development of new therapeutic agents or combined therapies is imperative. Growing evidence suggests that metformin treatment, due to its anti-inflammatory action, exerts a neuroprotective effect against ischemia/reperfusion-induced brain damage. Experimental assessment has typically been performed in models of cerebral transient ischemia followed by long-term reperfusion. The aim of this study was to evaluate the neuroprotective effect of metformin treatment after permanent middle cerebral artery occlusion (pMCAO) without reperfusion in rats. Neurological deficits were assessed using the Longa scale, which offers a graded scale on body movement following pMCAO. Both infarct size and brain oedema area were measured by staining with 2,3,5-triphenyltetrazolium chloride. The number of neurons and total and activated microglia, as well as interleukin 10 (IL-10) production, in brain sections were evaluated by immunohistochemical staining. Our results show that metformin treatment improves the neurological state and reduces infarct size after 120 h of pMCAO. Metformin also prevents neuronal loss in the ischemic cortex but not in the striatum after 48 h of pMCAO. Moreover, post-stroke treatment with metformin significantly decreases the number of total and activated microglia at 48 h. The anti-inflammatory effect of metformin is associated with increased IL-10 production at 48 h after pMCAO. The results of the present study suggest that post-stroke treatment with metformin exerts anti-inflammatory and neuroprotective effects in a pMCAO model.

Computational and Preclinical Evidence of Anti-ischemic Properties of L-Carnitine-Rich Supplement via Stimulation of Anti-inflammatory and Antioxidant Events in Testicular Torsed Rats.

Ischemia-reperfusion injury is a urological emergency condition that could lead to necrosis, testicular damage subfertility, and infertility. The purpose of this study was to identify changes taking place in the rat testis at short-term (4 hr) as well as long-term (7 days) reperfusion following testicular torsion and to evaluate the effects of Proxeed Plus (PP), L-carnitine-rich antioxidant supplement, on preventing these changes using the biochemical parameters and histopathology. Thirty adult male rats were divided into five groups: in groups, 1-4 testicular ischemia was achieved by rotating the left testis 720° clockwise for 4 h and dividing into the sham, torsion/detorsion (T/D), T/D+1000 mg/kg BW PP, and T/D+5000 mg/kg BW PP groups, respectively. PP was administered intraperitoneally 30 min before detorsion while group 5 served as the normal control. All rats were sacrificed 4 h after detorsion. The same experimental design was set up, and animals were sacrificed after 7 days of detorsion. The testicular levels of human cyclooxygenase-2; tumor necrosis factor; interleukins-1β, 6, and 10; hydrogen peroxide; malonaldehyde; superoxide dismutase; catalase; glutathione transferase; glutathione peroxidase; glutathione reductase; and histopathological damage were evaluated. Our results revealed that rats in the torsion/detorsion group exhibited elevated testicular levels of oxidative markers and proinflammatory cytokines, low levels of antioxidant enzymes, and severe histological alterations relative to the control and sham groups. Treatments with 1000 and 5000 mg/kg BW of PP for 4 hr and 7 days significantly (p < 0.05) decreased the levels of the proinflammatory and oxidative markers while increasing the spermatogenesis, testicular levels of antioxidant enzymes, and anti-inflammatory cytokine (IL-10) in a dose-dependent manner. This suggested that PP exhibited anti-inflammatory and antioxidant activities against I/R testes thus serving as an effective supplement to protect against testicular assault.

Effect of ischemic postconditioining on reaction of neocortex microglia after global brain ischemia in rats

Introduction. Ischemic postconditioning (IPostC) is a new concept in the brain protection strategy. Almost all researches in this area focus on the functioning and survival of neurons, while non-neuronal cells affected by IPostC remain unexplored.The aimis to study the IPostC effect on changes in microglia in the neocortex of Wistar rats after global brain ischemia during various periods of reperfusion.Materials and methods. Male Wistar rats were used as a model of a 10-minute global brain ischemia with a subsequent IPostC; the reperfusion-ischemia cycle was 15 s/15 s. In the early (2 days) and late (7 days) reperfusion periods, the number of morphologically unchanged neurons and Iba-1-positive nucleated microglyocytes in the occipital cortex was estimated.Results. It has been shown that global brain ischemia in rats leads to 25.9% (P&lt;0.05) neuron death and an increase of 30.9% (P&lt;0.05) in the number of Iba-1-positive microglia cells by the 2nd day of the reperfusion period in the occipital neocortex; by the 7th day of reperfusion, there was observed a neuron death significant increasing by 34.5% (P&lt;0.05) and the number of Iba-1-positive microglia cells increasing of 65.2% (P&lt;0.05) compared to similar indicators in sham-operated groups. The IPostC by 2 days of reperfusion was found to increase the number of unchanged neurons in the occipital region of the cerebral cortex by 18.3% (P&lt;0.05), which is not accompanied by a significant change in the number of Iba-1-positive microglial cells; by 7 days of reperfusion the increase number of unchanged neurons was found to be 23.5% (P&lt;0.05) in the analysed brain region , which is accompanied by a decrease in the number of Iba-1-positive microgliosis by 32.5% (P&lt;0.05) comparing with similar indicators in groups without IPostC.Conlusions. The results of this work suggest that the cytoprotective effect of IPostC for neurons of the occipital neocortex of Wistar rats in the long-term reperfusion period is caused by blocking the infiltration of the ischemic brain region by both resident and recruited cells of the immune system.

Astrocytic endothelin-1 overexpression promotes neural progenitor cells proliferation and differentiation into astrocytes via the Jak2/Stat3 pathway after stroke

BackgroundEndothelin-1 (ET-1) is synthesized and upregulated in astrocytes under stroke. We previously demonstrated that transgenic mice over-expressing astrocytic ET-1 (GET-1) displayed more severe neurological deficits characterized by a larger infarct after transient middle cerebral artery occlusion (tMCAO). ET-1 is a known vasoconstrictor, mitogenic, and a survival factor. However, it is unclear whether the observed severe brain damage in GET-1 mice post stroke is due to ET-1 dysregulation of neurogenesis by altering the stem cell niche.MethodsNon-transgenic (Ntg) and GET-1 mice were subjected to tMCAO with 1 h occlusion followed by long-term reperfusion (from day 1 to day 28). Neurological function was assessed using a four-point scale method. Infarct area and volume were determined by 2,3,5-triphenyltetra-zolium chloride staining. Neural stem cell (NSC) proliferation and migration in subventricular zone (SVZ) were evaluated by immunofluorescence double labeling of bromodeoxyuridine (BrdU), Ki67 and Sox2, Nestin, and Doublecortin (DCX). NSC differentiation in SVZ was evaluated using the following immunofluorescence double immunostaining: BrdU and neuron-specific nuclear protein (NeuN), BrdU and glial fibrillary acidic protein (GFAP). Phospho-Stat3 (p-Stat3) expression detected by Western-blot and immunofluorescence staining.ResultsGET-1 mice displayed a more severe neurological deficit and larger infarct area after tMCAO injury. There was a significant increase of BrdU-labeled progenitor cell proliferation, which co-expressed with GFAP, at SVZ in the ipsilateral side of the GET-1 brain at 28 days after tMCAO. p-Stat3 expression was increased in both Ntg and GET-1 mice in the ischemia brain at 7 days after tMCAO. p-Stat3 expression was significantly upregulated in the ipsilateral side in the GET-1 brain than that in the Ntg brain at 7 days after tMCAO. Furthermore, GET-1 mice treated with AG490 (a JAK2/Stat3 inhibitor) sh owed a significant reduction in neurological deficit along with reduced infarct area and dwarfed astrocytic differentiation in the ipsilateral brain after tMCAO.ConclusionsThe data indicate that astrocytic endothelin-1 overexpression promotes progenitor stem cell proliferation and astr ocytic differentiation via the Jak2/Stat3 pathway.

Chronic occlusion of the internal carotid artery: Endovascular revascularization technique of long occlusive lesions

BackgroundDespite series of endovascular recanalization of chronically occluded ICA (COICA) have been already reported, technical aspects of this strategy were not described. We discussed technical details and feasibility of this strategy. Clinical presentationFive COICA (C1-cavernous ICA) patients presenting symptomatic hypoperfusion were recanalized with multiple coronary and carotid stents. All patients experienced long-term reperfusion with resolution of the clinical symptoms. ConclusionEndovascular revascularization of COICA appears feasible and associated with improvement of the hypoperfusion.

Dissociation of eIF4E-binding protein 2 (4E-BP2) from eIF4E independent of Thr37/Thr46 phosphorylation in the ischemic stress response.

Eukaryotic initiation factor (eIF) 4E-binding proteins (4E-BPs) are translational repressors that bind specifically to eIF4E and are critical in the control of protein translation. 4E-BP2 is the predominant 4E-BP expressed in the brain, but their role is not well known. Here, we characterized four forms of 4E-BP2 detected by two-dimensional gel electrophoresis (2-DGE) in brain. The form with highest electrophoretic mobility was the main form susceptible to phosphorylation at Thr37/Thr46 sites, phosphorylation that was detected in acidic spots. Cerebral ischemia and subsequent reperfusion induced dephosphorylation and phosphorylation of 4E-BP2 at Thr37/Thr46, respectively. The induced phosphorylation was in parallel with the release of 4E-BP2 from eIF4E, although two of the phosphorylated 4E-BP2 forms were bound to eIF4E. Upon long-term reperfusion, there was a decrease in the binding of 4E-BP2 to eIF4E in cerebral cortex, demonstrated by cap binding assays and 4E-BP2-immunoprecipitation experiments. The release of 4E-BP2 from eIF4E was without changes in 4E-BP2 phosphorylation or other post-translational modification recognized by 2-DGE. These findings demonstrated specific changes in 4E-BP2/eIF4E association dependent and independent of 4E-BP2 phosphorylation. The last result supports the notion that phosphorylation may not be the uniquely regulation for the binding of 4E-BP2 to eIF4E under ischemic stress.

Cardioprotective effects of lixisenatide in rat myocardial ischemia-reperfusion injury studies

BackgroundLixisenatide is a glucagon-like peptide-1 analog which stimulates insulin secretion and inhibits glucagon secretion and gastric emptying. We investigated cardioprotective effects of lixisenatide in rodent models reflecting the clinical situation.MethodsThe acute cardiac effects of lixisenatide were investigated in isolated rat hearts subjected to brief ischemia and reperfusion. Effects of chronic treatment with lixisenatide on cardiac function were assessed in a modified rat heart failure model after only transient coronary occlusion followed by long-term reperfusion. Freshly isolated cardiomyocytes were used to investigate cell-type specific mechanisms of lixisenatide action.ResultsIn the acute setting of ischemia-reperfusion, lixisenatide reduced the infarct-size/area at risk by 36% ratio without changes on coronary flow, left-ventricular pressure and heart rate. Treatment with lixisenatide for 10 weeks, starting after cardiac ischemia and reperfusion, improved left ventricular end-diastolic pressure and relaxation time and prevented lung congestion in comparison to placebo. No anti-fibrotic effect was observed. Gene expression analysis revealed a change in remodeling genes comparable to the ACE inhibitor ramipril. In isolated cardiomyocytes lixisenatide reduced apoptosis and increased fractional shortening. Glucagon-like peptide-1 receptor (GLP1R) mRNA expression could not be detected in rat heart samples or isolated cardiomyocytes. Surprisingly, cardiomyocytes isolated from GLP-1 receptor knockout mice still responded to lixisenatide.ConclusionsIn rodent models, lixisenatide reduced in an acute setting infarct-size and improved cardiac function when administered long-term after ischemia-reperfusion injury. GLP-1 receptor independent mechanisms contribute to the described cardioprotective effect of lixisenatide. Based in part on these preclinical findings patients with cardiac dysfunction are currently being recruited for a randomized, double-blind, placebo-controlled, multicenter study with lixisenatide.Trial registration(ELIXA, ClinicalTrials.gov Identifier: NCT01147250)

Transgenic mice over-expressing endothelial endothelin-1 show cognitive deficit with blood–brain barrier breakdown after transient ischemia with long-term reperfusion

Increased level of endothelin-1 (ET-1), a potent vasoconstrictor, has been found in the cerebral spinal fluid (CSF) of patients with multi-infarction dementia, suggesting a possible role of ET-1 in cognitive deficit associated with stroke. Previously, we have reported that synthesis of ET-1 is induced in endothelial cells in hypoxic/ischemic conditions. Transgenic mice over-expressing endothelin-1 in endothelial cells (TET-1) developed systemic hypertension and showed more severe brain damage after transient ischemia. To further understand the significance of endothelial ET-1 in cognitive deficit, we subjected adult TET-1 mice to 30min middle cerebral artery occlusion (MCAO) with 7days reperfusion. At baseline, TET-1 mice showed similar locomotor activity, emotion and cognitive function compared to non-transgenic (NTg) mice. However, after 30min MCAO and 7days reperfusion, although the sensorimotor function measured by neurological scores was recovered in both genotypes, TET-1 mice showed increased anxiety-like behavior in the open field test and impaired spatial learning and reference memory in the Morris water maze. Parallel with these behavioral changes, TET-1 mice showed more severe brain damage with blood–brain–barrier breakdown (BBB), reactive astrogliosis, increased caspase-3, and increased peroxiredoxin 6 (Prx6) expressions around blood vessels in the ipsilateral hippocampus, compared to that of NTg mice, suggesting that ET-1 over-expression in the endothelial cells leads to more severe BBB breakdown and increased oxidative stress which may resulted in neuronal apoptosis and glial reactivity, which might contribute to the emotional changes and cognitive deficits after short-term ischemia with long-term reperfusion.

Abstract 8779: Effect of Cathepsin a Inhibition on Cardiac Function and Remodeling in Rats with Heart Failure Induced by Ischemia and Long-Term Reperfusion

Introduction: Cathepsin A (CathA) is a lysosomal carboxypeptidase involved in the cardiac metabolism of various peptide hormones. Its expression is significantly upregulated in the border zone after myocardial infarction (MI) in rats. Affymetrix profiling in MI patients revealed a similar regulation. Method: Male Wistar rats were randomized in: (1) Sham-OP, (2) I/R-Placebo (I/R=30min ischemia/reperfusion of the left coronary artery), (3) I/R-ramipril (RA 1 mg/kg/d p.o.), (4) I/R - CathA Inhibitor SAR1 (SAR1 30 mg/kg/d p.o.). After 9 weeks of treatment a magnetic resonance imaging (MRI)-investigation was done. Thereafter, left ventricles (LV) were fixed for histological evaluation and gene expression analysis by Taqman PCR. Brain natriuretic peptide (BNP) was measured in serum by ELISA. Results: Inhibition of CathA with SAR1 attenuated left ventricular (LV) remodeling observed after I/R without altering blood pressure. MRI analysis revealed preserved ventricular wall geometry in infarcted and non-infarcted regions. Global parameters such as ejection fraction, cardiac output, stroke volume, end-diastolic volume, end-systolic volume and left ventricle peak filling rate were significantly improved during dobutamin stress when compared to placebo treated I/R-rats. Especially the regional parameters such as wall motion and systolic wall thickness were improved in the infarcted area and even normalized in the non-infarcted area in SAR-treated I/R-rats. In contrast, RA treatment did not prevent the adverse remodeling. In all parameters SAR1 was clearly superior to RA. Histological investigations confirmed the beneficial effects of SAR1 treatment and serum levels of BNP were significantly reduced in SAR1 treated animals. LV gene expression of TGFβ, ANP, collagen type III and CD14 was decreased by ramipril and SAR1 treatment. Conclusion: We identified hitherto unknown functions of CathA in cardiac disease. Especially the dramatic improvement in LV wall geometry after inhibition of CathA with SAR1 makes this enzyme a highly promising target for the treatment of post-MI heart failure patients. SAR1 has the potential to introduce a new treatment option for patients with acute MI to further preserve myocardial function on top of standard treatment.

3-(R)-[3-(2-Methoxyphenylthio-2-(S)-methylpropyl]amino-3,4-dihydro-2H-1,5-benzoxathiepine Bromhydrate (F 15845) Prevents Ischemia-Induced Heart Remodeling by Reduction of the Intracellular Na+ Overload

The present study investigates whether 3-(R)-[3-(2-methoxyphenylthio-2-(S)-methylpropyl]amino-3,4-dihydro-2H-1,5-benzoxathiepine bromhydrate (F 15845), a new, persistent sodium current blocker, can reduce the ischemic Na(+) accumulation and exert short- and long-term cardioprotection after myocardial infarction. First, F 15845 concentration-dependently reduced veratrine-induced diastolic contracture (IC(50) = 0.14 microM) in isolated atria. Second, F 15845 from 1 microM preserved viability in 54.2 +/- 12.5% of isolated cardiomyocytes exposed to lysophosphatidylcholine. Third, the effect of F 15845 on intracellular Na(+) of isolated hearts from control and diabetic db/db mice was monitored using (23)Na-nuclear magnetic resonance spectroscopy. F 15845 (0.3 microM) significantly counteracted [Na(+)](i) increase during no-flow ischemia in control mouse hearts. In diabetic db/db mouse hearts, the reduction in [Na(+)](i) was delayed relative to control. However, it was more marked and maintained upon reperfusion. The cardioprotective properties after myocardial infarction associated with short- (24-h) and long-term (14-day) reperfusion were measured in anesthetized rats. After 24-h reperfusion, F 15845 (5 mg/kg) significantly reduced infarct size (32.4 +/- 1.7% with vehicle and 24.2 +/- 3.4% with F 15845; P < 0.05) and decrease of troponin I levels (524 +/- 93 microg/l with vehicle versus 271 +/- 63 microg/l with F 15845; P < 0.05). It is important that F 15845 limits the long-term expansion of infarct size (35.2 +/- 2.6%, n = 19 versus 46.7 +/- 1.6%, n = 27 in the vehicle group; P < 0.001). Overall, F 15845 attenuates [Na(+)](i) and prevents (or reverses) contractile and biochemical dysfunction in ischemic and remodeling heart. F 15845 constitutes a new generation of cardioprotective agent.

Sustained up-regulation of Semaphorin 3A, Neuropilin1, and Doublecortin expression in ischemic mouse brain during long-term recovery

Strategies to provide neuroprotection and to promote regenerative axonal outgrowth in the injured brain are thwarted by the plethora of axon growth inhibitors and the ligand promiscuity of some of their receptors. Especially, new neurons derived from ischemia-stimulated neurogenesis must integrate this multitude of inhibitory molecular cues, generated as a result of cortical damage, into a functional response. More often than not the response is one of growth cone collapse, axonal retraction and neuronal death. Therefore, characterization of the expression of inhibitory molecules in long-term surviving ischemic brains following stroke is important for designing selective therapeutics. Here, we describe a long-term recovery mouse model for cerebral ischemia in which a brief transient occlusion of the middle cerebral artery (30 min) was followed by up to 30 days of long-term reperfusion. Significantly decreased grip strength motor function and increased expression of one of the major repulsive guidance cues, Semaphorin 3A (Sema3A) and its receptor Neuropilin1 (NRP1) occurred in brains of these mice. Interestingly, increased Doublecortin (DCX) expression occurred only in the lateral ventricular wall zone, but not in the dentate gyrus granule cell layer on the ischemic side of the brain. Importantly, no DCX positive cells were detected in the infarct core region after 30 d ischemic recovery. Collectively, these studies demonstrated the sustained elevation of Sema3A/NRP1 expression in the ischemic territory, which may contribute to the inhibitory microenvironment responsible for preventing new neurons from entering the infarct area. This model will be of use as a platform for testing anti-inhibitory therapies to stroke.

Diagnostic Frequency Continuous Ultrasonography Directly Mitigates Venular Ischemia Reperfusion Damage

Our objective was to determine the effects of ischemia reperfusion (IR) treatment with continuous-mode diagnostic frequency ultrasonography exposure by assessing leukocyte-endothelial cell interactions, in terms of frequency and relative proportions of rolling and firmly attached leukocytes. Studies were carried out in the awake hamster chamber window preparation. Tourniquet ischemia was implemented by compressing a circular ring on the chamber window tissue for 4 hours, followed by reperfusion. Animals were randomly assigned into one of four groups as follows: IR; IR + ultrasonography; IR + N(omega)-nitro-L-arginine methyl ester (L-NAME); and IR + L-NAME + ultrasonography. Venules were exposed to epi-illumination, videorecorded, and leukocytes were categorized as "rolling"; flowing with endothelial contact; or "immobilized" cells, and counted during digital video-playback in 100-microm length segments. Leukocyte interaction with venular endothelium substantially decreased, during longterm reperfusion (p < 0.05) with ultrasonography exposure. Nitric oxide production inhibition, after L-NAME treatment, and ultrasonography exposure resulted in additional earlier substantially decreased leukocyte-endothelial cell interactions (p < 0.05). Venular function improvement, after IR damage, is a primary benefit derived from continuous-mode diagnostic frequency ultrasonography exposure. Although decreased interaction of adherent leukocytes can also be attributed to enhanced arteriolar flow, reduced interaction of rolling leukocytes is an immediate consequence of ultrasonography exposure.

Long-term inhibition of myocardial infarction by postconditioning during reperfusion

Cardioprotection with postconditioning has been well demonstrated after a short period of reperfusion. This study tested the hypothesis that postconditioning reduces infarct size, vascular dysfunction, and neutrophil accumulation after a long-term reperfusion. Canines undergoing 60 min left anterior descending artery (LAD) occlusion were divided into two control groups of either 3 h or 24 h of full reperfusion and two postconditioning groups with three 30 s cycles of reperfusion and re-occlusion applied at the onset of either 3 h or 24 h of reperfusion. Size of the area at risk (AAR) and collateral blood flow during ischemia were similar among groups. In controls, infarct size as percentage of the AAR (30 +/- 3 vs. 39 +/- 2* %) by TTC staining, superoxide anion generation from the post-ischemic coronary arteries by lucigenin-enhanced chemiluminescence [(89 +/- 5 vs. 236 +/- 27* relative light units (RLU/mg)], and neutrophil (PMN) accumulation by immunohistochemical staining in the AAR (52 +/- 11 vs. 84 +/- 14* cells/mm(2) myocardium) significantly increased between 3 and 24 h of reperfusion. Postconditioning reduced infarct size (15 +/- 4 and 27 +/- 3.6 %), superoxide anion generation (24 +/- 4 and 43 +/- 11 RLU/mg), and PMN accumulation (19 +/- 6 and 45 +/- 8 cells/mm(2) myocardium) in the 3 and 24 h reperfusion groups relative to time-matched controls. These data suggest that myocardial injury increases with duration of reperfusion; reduction in infarct size and attenuation in inflammatory responses with postconditioning persist after a prolonged reperfusion. * p < 0.05 24 vs. 3 h control; p < 0.05 postconditioning vs. time-matched control.

Is the ischemic blood–brain barrier insufficiency responsible for full-blown Alzheimer's disease?

The goal of this paper is to provide scientists with a comprehensive review of the state-of-the-art influence the ischemic blood–brain barrier (BBB) has on the final development of Alzheimer's disease and to provide detailed food-for-thought which will hopefully stimulate more researchers in this area of neuroscience. Understanding new and fundamental concepts about the behavior of the BBB during long-term reperfusion after ischemia with a variety of new neuropathogenic factors can hopefully provide some interesting clues related to the pathologic processes issues that have been receiving considerable attention in the human clinic. We present the recent data to understand the role of the BBB in maturation of both diseases and try to differentiate between primary and secondary pathologic mechanisms. In conclusion, the neuropathogenesis of Alzheimer's disease involves an initial ischemic neuronal alterations leading to enhanced neuronal vulnerability to β-amyloid peptide and the ischemic breakdown of the BBB with leakage of serum borne β-amyloid peptide into brain parenchyma, activation of β-amyloid peptide-dependent toxicity culminating in the formation of amyloid plaques and finally end in full-blown Alzheimer's disease. In summary, probably we have combined mechanism(s) of ischemia processes, ischemic and chronic BBB dysfunction and β-amyloid peptide-dependent injury in pathology of neurodegeneration that is observed in Alzheimer's disease. We speculate that Alzheimer's disease may be caused by silent and sublethal ischemic episodes that attack and slowly steal the minds of its victims. Finally, our review proposes the ischemic BBB-dependent mechanism(s) that probably are responsible for full-blown Alzheimer's disease.

Carnosine Protects the Brain of Rats and Mongolian Gerbils against Ischemic Injury: After-Stroke-Effect

Carnosine, a specific constituent of excitable tissues of vertebrates, exhibits a significant antioxidant protecting effect on the brain damaged by ischemic-reperfusion injury when it was administered to the animals before ischemic episode. In this study, the therapeutic effect of carnosine was estimated on animals when this drug was administered intraperitoneally (100 mg/kg body weight) after ischemic episode induced by experimental global brain ischemia. Treatment of the animals with carnosine after ischemic episode under long-term (7-14 days) reperfusion demonstrated its pronounced protective effect on neurological symptoms and animal mortality. Carnosine also prevented higher lipid peroxidation of brain membrane structures and increased a resistance of neuronal membranes to the in vitro induced oxidation. Measurements of malonyl dialdehyde (MDA) in brain homogenates showed its increase in the after brain stroke animals and decreased MDA level in the after brain stroke animals treated with carnosine. We concluded that carnosine compensates deficit in antioxidant defense system of brain damaged by ischemic injury. The data presented demonstrate that carnosine is effective in protecting the brain in the post-ischemic period.

The effects of vascular bed expansion in steatotic rat liver graft viability.

Disturbed microcirculation caused by fat accumulation in hepatocytes has been implicated in poor graft preservation and reperfusion. The aim of this study was to investigate the effect of vascular bed expansion (VBE) during cold preservation in graft survival Moderate liver steatosis in male Wistar rats (240-280 g) was induced by choline-deficient diet. Normal, steatotic or VBE-pretreated steatotic grafts were transplanted after 1 h or 9 h of cold preservation. Graft viability was determined by 7-day survival, serum liver enzymes, plasma tumour necrosis factor (TNF)-alpha, interleukin (IL)-6, and malondialdehyde (MDA) levels. Post-reperfusion bile flow and liver histology were also examined. After 9 h of preservation, VBE-pretreated steatotic liver grafts were associated with significantly reduced serum liver enzyme, plasma TNF-alpha, IL-6, and MDA levels, as well as increased bile flow and higher survival rates compared with untreated ones. The present study shows that VBE protects fatty liver grafts from subsequent long-term cold preservation and reperfusion injury in a rat liver transplantation model.

A vertical midline scar is a 'high-risk' factor for maximum survival of the rat TRAM flap.

The presence of any abdominal scar, in addition to obesity, a smoking history, and prior irradiation are considered the major known "risk factors" for predictable success or failure of the lower transverse rectus abdominis musculocutaneous (TRAM) flap. For many, a vertical midline scar has even been considered to be a relative contraindication. The possibility that the scar instead could effect some form of delay or by neovascularization permit reperfusion across the midline might negate this concern. The validity of this hypothesis was tested in 40 Sprague-Dawley (CD) rats using our standard rat TRAM flap model. Every rat initially had a vertical skin incision made from xiphoid to pubis. At a second stage, either immediately or after a delay of 1 week, 2 weeks, or 6 months, a superior-pedicled (dominant) or inferior-pedicled (nondominant) TRAM flap was raised, with five rats in each subgroup. For the inferior-pedicled group, the percentage of ipsilateral (muscle-pedicle half) flap survival approached 75% and had a trend toward greater survival with each increase in the time of delay, but any difference was not statistically significant (F= 0.653, P = 0.538). In the superior-pedicled group, the ipsilateral half of the flap always survived completely. In both groups, the contralateral or opposite side always underwent complete necrosis regardless of pedicle orientation or time constraints. The midline scar did not enhance even unilateral TRAM flap survival when compared with historic controls, and long-term transmidline reperfusion across the scar did not seem to occur. These findings corroborate the clinical observation that only a unilateral TRAM flap would be reliable in the presence of a vertical midline abdominal scar.