Methanesulfonyl fluoride, an acetylcholinesterase inhibitor, attenuates simple learning and memory deficits in ischemic rats

Methanesulfonyl fluoride (MSF), a highly selective CNS inhibitor of acetylcholinesterase, has been recently demonstrated to promote improvement in cognitive performance in patients with senile dementia of Alzheimer type. Because a similar cognitive impairment may accompany stroke, we investigated in the present study whether treatment with MSF could produce beneficial effects in adult rats subjected to an experimental stroke model. Sprague-Dawley rats received transient 60 min intraluminal occlusion of the right middle cerebral artery (MCAo) and were given i.p. injections of either MSF (1 mg/kg at 24 and 48 h post-MCAo and 0.3 mg/kg thereafter every other day) or the vehicle, peanut oil, for 4 weeks. Behavioral tests and biochemical assays were performed at 28 days post-surgery. MSF treatment produced about 90% inhibition of acetylcholinesterase in the brain. Ischemic animals that received the vehicle displayed significant elevated body swing biased activity (84.8 +/- 10%) and significantly prolonged acquisition (398 +/- 62 s) and shortened retention (79 +/- 26 s) of the passive avoidance task. Interestingly, while the ischemic animals that received the MSF exhibited elevated body swing biased activity (87.7 +/- 8%), they performed significantly better in the passive avoidance task (255 +/- 36 s and 145 +/- 18 s in acquisition and retention) than the vehicle-treated animals. Moreover, whereas brains from both groups of animals revealed similar extent and degree of cerebral infarction, the MSF-treated ischemic animals showed more intense immunoreactivity, as well as a significantly higher number (10-15% increase) of septal choline acetyltransferase-positive cells than the vehicle-treated ischemic animals. These results show that MSF, possibly by preserving a functional cholinergic system, attenuated stroke-induced deficits in a simple learning and memory task.

Targeting the JNK Signaling Pathway for Stroke and Parkinsons Diseases Therapy

The c-Jun NH2-terminal Kinase (JNK) signaling pathway is frequently induced by cellular stress and correlated with neuronal death. This unique property makes JNK signaling a promising target for developing pharmacological intervention. Among several neurological disorders, JNK signaling is particularly implicated in ischemic stroke and Parkinson's disease. The inhibitors of the JNK signaling pathway include upstream kinase inhibitors (for example, CEP-1347), small chemical inhibitors of JNK (SP600125 and AS601245), and peptide inhibitors of the interaction between JNK and its substrates (D-JNKI and I-JIP). The mechanisms by which JNK signaling induces apoptosis and evidence of cytoprotective effects of these JNK inhibitors are summarized in the present review.

Effect of Active Fraction of Cerebral on Expression of Caspase-3 and β-Amyloid Precursor Protein during Therapy of Hemorrhagic Stroke in the Acute and Delayed Periods

Active anti-stroke fraction of Cerebral preparation (extract of water-soluble molecules from brain tissue of animals with hemorrhagic stroke) decreased caspase-3 expression and improved survival of experimental animals in the acute period after hemorrhagic stroke.

Protein Kinase C Isozymes in Stroke

Stroke is a devastating neurologic disease and a leading cause of death and disability worldwide. Thrombolytic agents have been used to re-establish circulation in thromboembolic stroke, but their utility is limited by hemorrhage and reperfusion injury. Studies with experimental stroke models, mouse genetics, and selective peptide inhibitors and activators have implicated protein kinase C (PKC) epsilon in ischemic preconditioning and PKCdelta and gamma in tissue injury. PKCdelta, resident both in neutrophils and in the brain, appears particularly essential for reperfusion injury, and recent work using PKCdelta-specific peptide inhibitors suggests that PKCdelta inhibitors could prove useful in attenuating reperfusion injury and improving outcome following thrombolysis.

Impact of oxidative stress on neuronal survival

1. Reactive oxygen species and oxidative state are slowly gaining acceptance in having a physiological relevance rather than just being the culprits in pathophysiological processes. The control of the redox environment of the cell provides for additional regulation in relation to signal transduction pathways. Conversely, aberrant regulation of oxidative state manifesting as oxidative stress can predispose a cell to adverse outcome. 2. The phosphatidylinositol 3-kinase/akt pathway is one such pathway that is partially regulated via oxidative state and, in an oxidative stress paradigm such as ischaemic-reperfusion injury, may be inactivated, which can lead to exacerbation of cell death. 3. Activation of nuclear factor (NF)-kappaB has been associated with oxidative stress. The role of NF-kappaB in neuronal cell death is widely debated, with major studies highlighting both a pro- and anti-apoptotic role for NF-kappaB, with the outcome being region, stimulus, dose and duration specific. 4. Oxidative state plays a key role in the regulation and control of numerous signal transduction pathways in the cell. Elucidating the mechanisms behind oxidative stress-mediated neuronal cell death is important in identifying potential putative targets for the treatment of diseases such as stroke.

MTHFR C677T gene mutation as a risk factor for arterial stroke: a hospital based study

Elevated homocysteine level is an independent risk factor for ischemic stroke, thrombotic and cardiovascular diseases. The enzyme methylenetetrahydrofolate reductase (MTHFR) plays a crucial role in regulating the levels of homocysteine. A C677T mutation in this gene results in reduced activity. Sixty-nine patients with arterial stroke, six patients with venous stroke (confirmed by computed tomography and/or magnetic resonance imaging) with hyperhomocysteinemia were selected for the study. Forty-nine subjects with no past history of stroke served as controls. MTHFR genotypes were determined by PCR using specific primers, followed by restriction digestion and gel analysis. The prevalence of the mutated homozygous and heterozygous C677T MTHFR genotype in the patients with arterial stroke was 1.4% (one of 69) and 31.88% (21 of 69), respectively. There frequency was 16.6% (one of six) and 33.3% (two of six) in venous stroke. The genotyping results from controls showed that there was only one heterozygote out of the 49 studied (2.08%). There was a significant difference between the control and the patient groups. Odds ratio for the probability of the C677T MTHFR gene mutation in the patients versus control group was 22.29 (95% CI 4.89-98.8). This indicates that C677T MTHFR mutation is strongly associated with arterial stroke especially in young adults. MTHFR allele evaluation will help in preventing/reducing morbidity caused by stroke.

Stroke Outcomes in Mice Lacking the Genes for Neuronal Heme Oxygenase-2 and Nitric Oxide Synthase

Heme oxygenase-2 (HO-2) has been suggested to be a cytoprotective enzyme in a variety of in vivo experimental models. HO-2, the constitutive isozyme, is enriched in neurons and, under normal conditions, accounts for nearly all of brain HO activity. HO-2 deletion (HO-2-/-) leads to increased neurotoxicity in cultured brain cells and increased damage following transient cerebral ischemia in mice. Moreover, pharmacologic inhibition of HO activity significantly augments focal ischemic damage in wildtype (WT) mice, but does not further exacerbate it in HO-2-/- mice. The HO system shares some similarities with nitric oxide synthase (NOS), notably their syntheses of carbon monoxide (CO) and nitric oxide (NO), respectively, which are diffusible gases with numerous biological actions, including neurotransmission and vasodilation. While deletion of HO-2 results in greater stroke damage, the pharmacologic inhibition of neuronal nitric oxide synthase (nNOS), or its gene deletion, confers neuroprotection in animal models of transient cerebral ischemia. To investigate the interactions, the outcome of focal cerebral ischemia-reperfusion in double knockout (HO-2-/- X nNOS-/-) mice lacking both genes was compared to control WT mice. Wildtype and double knockout male mice underwent intraluminal middle cerebral occlusion for 2 hours, followed by reperfusion for 22 hours. Outcomes in neurologic deficits and infarct size were determined. No difference was observed between WT and double knockout mice in the volume of infarction, neurologic signs, decrease in relative cerebral blood flow during ischemia, or core body temperature. The results suggest that the deleterious action of nNOS would counteract the role of HO-2 in neuroprotection.

[A case-control study on the relationship between stroke and plasma homocysteine level and the mutation of MTHFR gene]

OBJECTIVE

To study the relationship of stroke and plasma homocysteine (Hcy) level and the mutation of methylenetetrahydrofolate reductase (MTHFR) gene.

METHODS

Three hundred patients with stroke were included as the case group in this study while 300 subjects without stroke matched with the case group for sex and age were collected as the control group. Plasma Hcy level was measured using HPLC and MTHFR 667C-->T mutant was determined by polymerase chain reaction and restriction fragment analysis. The relationship of stroke and plasma Hcy level and the mutation of MTHFR gene was then analysed.

RESULTS

The plasma Hcy level of the case group was significantly higher than that of the control group (16.92 +/- 3.43 micromol/L vs. 14.57 +/- 2.59 micromol/L, P <0.05). There was no significant difference in mutation rate of MTHFR C677T between stroke group and control group (P >0.05), as well as between ischemic stroke group and homorrhagic stroke group (P >0.05). The mutation of MTHFR C677T had no significant influence on the Hcy level (15.28 +/- 2.17 micromol/L vs. 15.11 +/- 3.81 micromol/L, P >0.05).

CONCLUSION

Increased plasma Hcy level played an important role in the occurrence of stroke in Chinese people, and the mutation of MTHFR C677T was not associated with Hcy level or stroke which led to the speculation that plasma Hcy level was important in the prevention of cardio-cerebro-vascular diseases among Chinese people.

Antioxidant Status in Acute Stroke Patients and Patients at Stroke Risk

BACKGROUND AND PURPOSE

Antioxidant enzymes like copper/zinc superoxide dismutase (SOD), catalase and gluthatione peroxidase (GSHPx) are part of intracellular protection mechanisms to overcome oxidative stress and are known to be activated in vascular diseases and acute stroke. We investigated the differences of antioxidant capacity in acute stroke and stroke risk patients to elucidate whether the differences are a result of chronic low availability in arteriosclerosis and stroke risk or due to changes during acute infarction.

METHODS

Antioxidant enzymes were examined in 11 patients within the first hours and days after acute ischemic stroke and compared to risk- and age-matched patients with a history of stroke in the past 12 months (n = 17). Antioxidant profile was determined by measurement of glutathione (GSH), malondialdehyde (MDA), SOD, GSHPx and minerals known to be involved in antioxidant enzyme activation like selenium, iron, copper and zinc.

RESULTS

In comparison to stroke risk patients, patients with acute ischemic stroke had significant changes of the GSH system during the first hours and days after the event: GSH was significantly elevated in the first hours (p < 0.01) and GSHPx was elevated 1 day after the acute stroke (p < 0.05). Selenium, a cofactor of GSHPx, was decreased (p < 0.01). GSHPx levels were negatively correlated with National Institutes of Health Stroke Scale (NIHSS) scores on admission (r = -0.84, p < 0.001) and NIHSS scores after 7 days (r = -0.63, p < 0.05). MDA levels showed a trend for elevation in the first 6 h after the acute stroke (p = 0.07). No significant differences of SOD, iron, copper nor zinc levels could be identified.

CONCLUSIONS

Differences of antioxidant capacity were found for the GSH system with elevation of GSH and GSHPx after acute stroke, but not for other markers. The findings support the hypothesis that changes of antioxidant capacity are part of acute adaptive mechanisms during acute stroke.

MTHFR C677T polymorphism and its relation to ischemic stroke in the Black Sea Turkish population

The MTHFR C677T mutation has been shown to be associated with venous thrombosis. The role of this mutation in ischemic stroke is unclear. We investigated whether the MTHFR mutation is a risk factor for patients with ischemic stroke in the Black Sea Turkish population or not. We analyzed 30 patients (19 male, 11 female) [median age: 50 years (range: 28-78)] with ischemic stroke who had no known predisposition factors for stroke and 242 (182 male, 60 female) healthy controls [median age: 42 years (range: 18-65)]. Detection of the MTHFR C677T mutation was performed by using commercially available allele-specific PCR-ELISA kits. Prevalence of the MTHFR C677T genotype was 49.1% (CT, 45.8%; TT, 3.3%) in controls and 50% (CT, 43.3%; TT, 6.6%) in patients [OR: 1.03, 95% CI (0.45-2.35]). The prevalence of homozygous gene mutation for MTHFR was higher among patients with stroke than control subjects, but this difference was not statistically significant. The MTHFR gene mutation is not a risk factor for ischemic stroke formation in patients from the Black Sea region in Turkey.

Ubiquitin-proteasome system and proteasome inhibition: new strategies in stroke therapy

BACKGROUND AND PURPOSE

Proteasomes are large multicatalytic proteinase complexes that are found in the cytosol and in the nucleus of eukaryotic cells with a central role in cellular protein turnover. The ubiquitin-proteasome system (UPS) has a central role in the selective degradation of intracellular proteins. Among the key proteins whose levels are modulated by the proteasome are those involved in the control of inflammatory processes, cell cycle regulation, and gene expression. There are now overwhelming data suggesting that the UPS contributes to cerebral ischemic injury.

SUMMARY OF REVIEW

Proteasome inhibition is a potential treatment option for stroke. Thus far, proof of principle has been obtained from studies in several animal models of cerebral ischemia. Treatment with proteasome inhibitors reduces effectively neuronal and astrocytic degeneration, cortical infarct volume, infarct neutrophil infiltration, and NF-kappaB immunoreactivity with an extension of the neuroprotective effect at least 6 hours after ischemic insult. However, it is clear that the UPS represents a central pathway for the processing and metabolism of multiple proteins with critical roles in cellular function. To avoid eliciting significant side effects associated with complete inhibition of the proteasome and the possible immunosuppressive effects from persistent suppression of NF-kappaB activation, it is critical that we understand how to partially and temporally attenuate proteasome function to elicit the desired therapeutic effect before any large-scale use in humans.

CONCLUSIONS

This review highlights the most recent advances in our knowledge on UPS, as well as the early experience of using proteasome inhibition strategies to treat acute stroke.

[Relationship between polymorphisms of cystathionine beta-synthase gene and stroke]

OBJECTIVE

To determine whether the T27796C mutation in cystathionine beta-synthase (CBS) gene is associated with stroke in Chinese.

METHODS

The T27796C mutation in CBS gene of 59 cases with stroke and 65 health controls were detected by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP).

RESULTS

As this investigation shown, the frequencies of two alleles of T27796C mutation were followed: C was 56.8%, T was 43.2% in cases and C was 51.5%, T was 48.5% in controls. T27796C mutation had no obvious relativity to the stroke (P>0.05). There was no significant difference in frequency of alleles of this mutation between cases and controls (CC: 35.6% vs. 24.6%; CT: 42.4% vs. 53.8%; TT: 22.0% vs. 21.5%; all P>0.05). There was not obvious difference in frequency of alleles of this mutation between hemorrhagic patients and ischemic stroke patients (all P>0.05).

CONCLUSION

T27796C mutation in CBS is not obviously correlated with stroke and this mutation is not associated with categories of stroke.

Red cell N5-methyltetrahydrofolate concentrations and C677T methylenetetrahydrofolate reductase genotype in patients with stroke

AIMS

To investigate the relation between total red cell folate, red cell N(5)-methyltetrahydrofolate (N(5)MTHF) concentrations, and N(5)N(10)-methylenetetrahydrofolate reductase (MTHFR) genotypes in stroke.

METHODS

The study comprised 120 consecutive patients presenting to hospital with acute stroke. Multivitamin supplement use was recorded. Serum and red cell folate were measured by microbiological assays using Lactobacillus casei and Enterococcus faecalis, and by the DPC-BioMediq Immulite 2000 analyser. Total plasma homocysteine (tHcy), serum cobalamin, and serum vitamin B(6) were measured and the C677T MTHFR genotype determined.

RESULTS

There were no significant differences in blood tHcy or vitamin concentrations according to MTHFR genotype in the overall patient cohort. However, when patients taking vitamins were excluded, total red cell folate and red cell N(5)MTHF were significantly lower in patients with the TT genotype compared with CT or CC genotypes. In the overall cohort, irrespective of genotype, red cell folate was significantly lower when assayed microbiologically than with the Immulite assay. This discrepancy remained after exclusion of patients taking vitamins.

CONCLUSION

Total red cell folate and red cell N(5)MTHF are significantly lower in stroke patients with the TT compared with the CT and TT MTHFR genotypes, particularly those not taking vitamin supplements. Microbiological assays that measure biologically active folates provide substantially lower estimates of folate than the Immulite assay. Because folate is a key determinant of blood homocysteine values, these findings may impact on the interpretation of the strength and independence of the association between raised blood concentrations of homocysteine and atherothrombosis risk reported in most epidemiological studies.

Safety Profile of Tissue Plasminogen Activator Treatment Among Stroke Patients Carrying a Common Polymorphism (C-1562T) in the Promoter Region of the Matrix Metalloproteinase-9 Gene

Background and Purpose— Matrix metalloproteinase-9 (MMP-9) expression, related to blood-brain barrier disruption, has been implicated in the appearance of hemorrhagic transformation (HT) after tissue plasminogen activator (tPA) treatment in stroke patients. Because an in vitro functional polymorphism of the promoter region of MMP-9 gene (C-1562T) has been described, we hypothesize that patients carrying this mutation might have higher MMP-9 levels and greater susceptibility to developing HT when receiving tPA.

Methods— We studied strokes involving the middle cerebral artery territory of 61 patients who received tPA <3 hours after stroke onset. Blood samples were obtained before tPA administration. Plasmatic MMP-9 determinations were performed (enzyme-linked immunosorbent assay, ng/mL), and C-1562T genotype was determined by polymerase chain reaction. Healthy age-matched control subjects were used to study allele distribution (n=59). Hemorrhagic events were classified according to CT criteria (petechial hemorrhagic infarctions [HI,1 to 2] and large parenchymal hemorrhages [PH,1 to 2]).

Results— Allele distribution was similar in patients and control subjects (CC/CT/TT: 72.3/27.7/0% versus 79.7/20.3/0%, respectively; P =0.37). Among patients, mutation carriers (CT/TT alleles) had similar rates of HT and PH than noncarriers (HT: 23.1% versus 38.2%, P =0.49; PH: 15.4% versus 17.6%, P =1.0). Although the highest MMP-9 level corresponded to patients who later developed a PH (PH, 191.4 ng/mL; non-PH, 68.05 ng/mL; P =0.022), no relation between MMP-9 mutation presence and plasmatic levels was found (CC, 127.12 ng/mL; CT/TT, 46.31 ng/mL; P =0.11).

Conclusions— Although MMP-9 level predicts PH appearance after tPA treatment, no relationship exists with the C-1562T polymorphism, probably because this mutation is not functional in response to cerebral ischemia in vivo.

The proteasome system and proteasome inhibitors in stroke: controlling the inflammatory response

The ubiquitin-proteasome pathway (UPP) is a predominantly non-lysosomal protein degradation pathway responsible for degrading many critical regulatory proteins (e.g., nuclear factor-kappa B). This pathway is widely known for its ubiquitous role in immune and inflammatory responses, control of cell growth and apoptosis. These roles are apparent in the nervous system, but neurons and their neighboring cells also employ the UPP for distinct functions, ranging from development to the co-ordination of cellular responses, injury of the nervous system and brain-specific processes such as aging and memory. Promising results from preclinical studies in animal models indicate that the use of specific proteasome inhibitors to manipulate UPP may prove valuable in treating such conditions as ischemic stroke.

Gene expression profiling and functional proteomic analysis reveal perturbed kinase-mediated signaling in genetic stroke susceptibility

The stroke-prone spontaneously hypertensive rat (SHRSP) is a model of heritable hypertension-associated cerebrovascular injury. This study sought to compare SHRSP to the stroke-resistant SHR strain to identify genes and protein pathways whose expression and/or function was significantly altered between the strains prior to the onset of stroke. Cerebral cortex gene expression profiles from male SHRSPs and matched SHRs were examined by Affymetrix microarray analysis. mRNAs encoding the brain-derived neurotrophic factor receptor (TrkB) and multiple kinases of the MAPK/AKT signaling pathways, including JNK2, AKT2, and PI3K, were differentially expressed between SHRSP and SHR. Because these data suggest altered function in pathways involving MAP and AKT kinase activity, we performed Western blot using phosphorylation state-specific antibodies to characterize activity of MAP kinase and PI3K/AKT pathways. Changes in the levels of the phosphorylated forms of these kinases paralleled the changes in transcript levels observed between the strains. Two-dimensional gel electrophoresis and peptide fragment mass fingerprinting were used to identify altered protein substrates of these kinases. Protein profiling of kinase substrates further supported the notion of perturbed kinase-mediated signaling in SHRSP and identified adenylyl cyclase associated protein 2, TOAD-64, propionyl CoA carboxylase, APG-1, and valosin-containing protein as kinase targets whose phosphorylation state is altered between these strains. Altered gene and protein expression patterns in SHRSP are consistent with increased vulnerability of this strain to cerebrovascular injury.

Up-Regulation of Secretory Leukocyte Protease Inhibitor (SLPI) in the Brain after Ischemic Stroke: Adenoviral Expression of SLPI Protects Brain from Ischemic Injury

Secretory leukocyte protease inhibitor (SLPI) is a 12-kDa secreted protein initially identified from epithelial cells as an inhibitor of leukocyte serine proteases. In the present study, we described the identification of SLPI expression in ischemic cortex by suppression subtractive hybridization strategy. Our full-length rat SLPI cDNA shares 81% and 63% amino acid sequence identity with its mouse and human homologs, respectively, and with several polymorphisms to previous reported rat sequences. Northern blot analysis confirmed that SLPI mRNA was significantly induced in the ischemic brain tissue at 12 h (5.1-fold increase over sham controls, n = 4, p < 0.05), peaked at 2 days (26.1-fold increase, p < 0.001), and sustained up to 5 days (5.1-fold increase, p < 0.05). SLPI was localized in neurons and astrocytes in the peri-infarct zone from 24 to 72 h after middle cerebral artery occlusion by means of immunohistochemical and confocal microscopy analysis. Administration of a recombinant adenovirus overexpressing SLPI (Adv/SLPI) into the cortical tissue resulted in up to 58.4% reduction in ischemic lesion over controls at the site of Adv/SLPI expression (p < 0.01, n = 8) and significantly improved functional outcome (p < 0.01). These data suggest that the ischemia-induced expression of SLPI might play a neuroprotective role in focal stroke, possibly because of rapid inhibition of activated proteases and its suppression in inflammatory response.

Mechanisms of stroke protection by physical activity

Regular physical activity is associated with a decrease of cerebrovascular and cardiovascular events, which may relate to enhanced endothelium-dependent vasodilation. Here, we provide evidence that physical activity protects against ischemic stroke via mechanisms related to the upregulation of endothelial nitric oxide synthase (eNOS) in the vasculature. Voluntary training on running wheels or exercise on a treadmill apparatus for 3 weeks, respectively, reduced cerebral infarct size and functional deficits, improved endothelium-dependent vasorelaxation, and augmented cerebral blood flow in wild-type mice. The neuroprotective effects of physical training were completely absent in eNOS-deficient mice, indicating that the enhanced eNOS activity by physical training was the predominant mechanism by which this modality protects against cerebral injury. Our results suggest that physical activity not only decreases stroke risk, but also provides a prophylactic treatment strategy for increasing blood flow and reducing brain injury during cerebral ischemia.

Serum chitotriosidase activity is increased in subjects with atherosclerosis disease

OBJECTIVE

This study was undertaken to analyze the relation between serum activity of chitotriosidase enzyme, a protein synthesized exclusively by activated macrophages, and atherosclerotic lesion extent in subjects with atherothrombotic stroke (ATS) and in subjects with ischemic heart disease (IHD).

METHODS AND RESULTS

We assayed the serum chitotriosidase activity and a common chitotriosidase gene polymorphism that causes deficiency in chitotriosidase activity in 3 Spanish populations, ATS (n=153), IHD (n=124), and control (n=148) subjects. Statistical differences were found in serum chitotriosidase activity between ATS (88.1+/-4.6 nmol/mL. h, P<0.0001) and IHD subjects (79.0+/-6.3, P=0.002) versus control group (70.9+/-5.2). These observed differences were not attributable to a distinct allelic or genotype distribution. The extension of the atherosclerotic lesion in carotids of ATS subjects was measured by duplex sonography. Chitotriosidase activities were 66.9+/-9.6, 88.7+/-8.3, and 107.7+/-11.8 for subjects with carotid stenosis <or=30%, 31% to 60%, and >60%, respectively. Statistical differences were observed between subjects with major and intermediate stenosis grade compared with subjects with minor stenosis, P=0.005 and P=0.016, respectively.

CONCLUSIONS

Serum chitotriosidase activity is significantly increased in individuals suffering from atherosclerosis disease and is related to the severity of the atherosclerotic lesion, suggesting a possible role as atherosclerotic extent marker.

Endogenous proteolytic activity in a rat model of spontaneous cerebral stroke

We evaluated the expression of two extra-cellular protease systems in a model of spontaneous cerebrovascular pathology: spontaneously hypertensive stroke-prone rats (SHRSP). The appearance of brain damage in individual animals was imaged and followed by means of magnetic resonance imaging (MRI). In situ zymography of brain slices obtained 3 days after the appearance of brain damage showed an increase in plasminogen activator (PA)/plasmin activity that co-localised with the cerebral damage detected by MRI; there was also concomitant accumulation/activation of inflammatory cells in the damaged area. Proteolytic activity was inhibited by the urokinase-specific inhibitor amiloride but not by an antibody against tissue-type plasminogen activator (t-PA). SDS-PAGE zymography of brain extracts revealed the presence of 58 kDa plasminogen-dependent lysis areas in the ischemic and non-ischemic tissues, and a 33 kDa lysis area in ischemic tissue only. An antibody against t-PA inhibited the former, whereas the latter was inhibited by amiloride. The specific induction of urokinase-type plasminogen activator (u-PA) in the damaged tissue was further confirmed by the fact that both u-PA protein mass and mRNA were markedly increased in the damaged cerebral areas. Concomitant metalloproteinase-2 (MMP-2) activation was only observed in the damaged area. These data suggest that u-PA is expressed and selectively catalyses proteolysis in the injured area of spontaneous brain damage in SHRSP.

Increase in plasma matrix metalloproteinase-9 in acute stroke patients with thrombolysis failure

BACKGROUND AND PURPOSE

Platelet-rich thrombi are resistant to thrombolytics. Matrix metalloproteinases (MMPs) may be involved in platelet aggregation and contribute to thrombolysis failure in stroke patients.

METHODS

Plasma samples from 23 stroke patients who had received thrombolytics and from 47 healthy volunteers were examined for MMP-2 and MMP-9 by both enzyme-linked immunosorbent assays and zymography.

RESULTS

The arteries were recanalized in 15 patients but not in the other 8. The MMP-9 plasma level was significantly higher in patients whose arteries were not recanalized.

CONCLUSIONS

MMP-9 may be associated with the formation of a thrombolytics-resistant thrombus.

Perspectives on reperfusion-induced damage in rodent models of experimental focal ischemia and role of gamma-protein kinase C

Ischemic stroke represents the leading cause of death and disability among elderly people. Most stroke survivors are left with lifelong disability. With the exception of tissue-type plasminogen activator (t-PA), no effective therapy exists for the management of acute stroke. Understanding the role of various extrinsic and intrinsic pathogenic factors of ischemic damage represents a prime objective of ongoing stroke research. An important variable affecting stroke outcome is the presence or absence of reperfusion (recanalization of the occluded vessel) following an ischemic event. It appears that early reperfusion after a stroke is beneficial and capable of reversing the majority of ischemic dysfunctions. However, in some instances, late reperfusion may contrarily trigger deleterious processes and lead to more ischemic damage. Examples of ischemia/reperfusion damage using an experimental model of focal ischemia in rodents are provided, along with evidence that the brain-enriched gamma-isoform of protein kinase C may represent an important mediator of reperfusion-induced brain injury in mutant mice.

Apoptosis and brain ischaemia

There is increasing evidence that some neuronal death after brain ischaemia is mediated by the action of cysteine-requiring aspartate-directed proteases (caspases), the proteases responsible for apoptosis in mammals, although this form of neuronal death is not always accompanied by the morphological changes that are typical of apoptosis in other tissues. Caspase-mediated neuronal death is more extensive after transient than permanent focal brain ischaemia and may contribute to delayed loss of neurons from the penumbral region of infarcts. The activation of caspases after brain ischaemia is largely consequent on the translocation of Bax, Bak, and other BH3-only members of the Bcl-2 family to the mitochondrial outer membrane and the release of cytochrome c, procaspase-9, and apoptosis activating factor-1 (Apaf-1) from the mitochondrial intermembrane space. How exactly ischaemia induces this translocation is still poorly understood. NF-kappaB, the c-jun N-terminal kinase-c-Jun pathway, p53, E2F1, and other transcription factors are probably all involved in regulating the expression of BH3-only proteins after brain ischaemia, and mitochondrial translocation of Bad from sequestering cytosolic proteins is promoted by inactivation of the serine-threonine kinase, Akt. Other processes that are probably involved in the activation of caspases after brain ischaemia include the mitochondrial release of the second mitochondrial activator of caspases (Smac) or direct inhibitor-of-apoptosis-binding protein with low pI (DIABLO), the accumulation of products of lipid peroxidation, a marked reduction in protein synthesis, and the aberrant reentry of neurons into the cell cycle. Non-caspase-mediated neuronal apoptosis may also occur, but there is little evidence to date that this makes a significant contribution to brain damage after ischaemia. The intracellular processes that contribute to caspase-mediated neuronal death after ischaemia are all potential targets for therapy. However, anti-apoptotic interventions in stroke patients will require detailed evaluation using a range of outcome measures, as some such interventions seem simply to delay neuronal death and others to preserve neurons but not neuronal function.

Matrix metalloproteinase-9 pretreatment level predicts intracranial hemorrhagic complications after thrombolysis in human stroke

BACKGROUND

Matrix metalloproteinase (MMP) expression is related to blood brain barrier disruption after cerebral ischemia. Moreover, MMP inhibitors reduce hemorrhagic transformation (HT) after embolic ischemia in tissue plasminogen activator (t-PA)-treated animals. We aimed to correlate plasmatic MMP levels with the appearance of intracranial bleeding complications in stroke patients treated with t-PA.

METHODS AND RESULTS

Serial MMP-2 and MMP-9 determinations were performed (ELISA, ng/mL) in 41 strokes involving the middle cerebral artery territory in patients who received t-PA within 3 hours of stroke onset. Blood samples were obtained at baseline (pretreatment) and at 12 and 24 hours after symptom onset. Hemorrhagic events were classified according to CT criteria (petechial hemorrhagic infarctions [HI, 1 to 2] and large parenchymal hemorrhages [PH, 1 to 2]). Brain CT scan was obtained at 48 hours or when a neurological worsening occurred. HT was present in 36.5% of the patients (24.4% HI and 12.1% PH). MMP-2 values were unrelated to any subtype of HT. The highest baseline MMP-9 level (normal range <97 ng/mL) corresponded to patients who later developed a PH (PH: 270.2+/-87.8, non-HT: 126.3+/-127.5, HI: 94.6+/-88.7; P=0.047). A graded response was found between mean baseline MMP-9 levels and the degree of bleeding (HI-1=37.4; HI-2=111.0; PH-1=202.5; PH-2=337.8). Baseline MMP-9 was the most powerful predictor of PH appearance in the multiple logistic regression model (OR= 9.62; CI 1.31 to 70.26; P=0.025).

CONCLUSIONS

Baseline MMP-9 level predicts PH appearance after t-PA treatment. Therefore, we suggest that MMP determination may increase the safety profile for thrombolysis and, in the future, anti-MMP drugs might be combined with t-PA to prevent hemorrhagic complications.

Are serum S100beta proteins and neuron-specific enolase predictors of cerebral damage in cardiovascular surgery?

OBJECTIVE

To examine whether serum concentrations of S100beta protein and neuron-specific enolase (NSE) are predictors of cerebral damage in cardiovascular surgery.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PARTICIPANTS

Eighteen patients with conventional cardiopulmonary bypass (CPB), 7 with selective cerebral perfusion (SCP), and 3 volunteers (blood samples).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

S100beta and NSE were measured in the blood obtained at 7 time points during and after operation. The concentrations of these markers in the blood from the surgical field and the cell-saver device, and the influence of graded hemolysis (in vitro) on the concentrations of these proteins were also examined. The mean values of S100beta in the CPB group (2.08 +/- 2.00 ng/mL) and the SCP group (1.46 +/-0.77 ng/mL) were highest after aortic declamping and after termination of SCP, respectively. The mean values of NSE in the CPB group (29.1 +/- 14.0 ng/mL) and the SCP group (31.2 +/- 13.6 ng/mL) were highest after termination of CPB and at the end of the operation, respectively. Three patients suffered from cerebral complications, but the elevation of these markers during operation was indistinguishable from those in the other patients. Peak concentrations of S100beta protein in the CPB group and NSE in the SCP group were correlated with the duration of aortic cross-clamping and CPB, respectively. S100beta protein and NSE concentrations in the blood from the surgical field were significantly larger than those in arterial blood, whereas the concentrations in the blood in the cell-saving device were not elevated. The concentration of S100beta protein was not influenced by the extent of hemolysis, whereas NSE concentration was markedly elevated by hemolysis.

CONCLUSION

A large part of the increases in S100beta protein and NSE during CPB and SCP is not attributed to neuronal damage, but to contamination with the blood from the surgical field. To determine whether these markers are useful to predict neurologic complications, it will be necessary to exclude contamination from the surgical field as observed in the present study.

Stroke in young patients with hyperhomocysteinemia due to cystathionine beta-synthase deficiency

BACKGROUND

Although hyperhomocyst(e)inemia (Hyper-Hcy) may predispose to atherosclerosis and venous thrombosis, the mechanisms of stroke associated with Hyper-Hcy are not defined.

METHODS

Clinical and biochemical phenotypes and genetic features of three unrelated patients with premature stroke and severe Hyper-Hcy due to cystathionine beta-synthase (CBS) deficiency are described. Plasma Hcy and amino acids were measured by fluorescence polarization immune assay and ion exchange chromatography. Analysis of the CBS and methylenetetrahydrofolate reductase genes was performed by restriction enzyme digestion and sequence analysis.

RESULTS

Two of the three index cases had no known diagnosis of homocystinuria and initially presented with embolic cerebral and retinal infarction in mid-adulthood. Mechanisms of cerebrovascular disease were carotid intraluminal thrombosis, arterial dissection, and possible cardiac embolism. Family screening revealed additional members with clinically silent homocystinuria and severe Hyper-Hcy. Excluding tall stature in two individuals, all had mild phenotypes, without classic findings of CBS deficiency. Plasma total and free Hcy, methionine, and urine Hcy were elevated. Genotyping revealed heterozygous CBS mutations (I278T, D444N, G307S) in affected individuals.

CONCLUSION

Artery-to-artery embolism and dissection may cause stroke in young adults with homocystinuria. The results also support a rationale for screening for Hyper-Hcy in young adults with stroke without a phenotype suggestive of classic homocystinuria.

[Correlation between the nucleic acid homeostasis disorders and location of ischemic insult and its consequences]

The characteristic feature of ischaemic insult was the excess of the majority components of the nucleinic homeostasis (DNA, RNA, DNA-ases) in the blood serum of the patients with unfavourable development of process and the low activity of ribonucleases. This tendency was also observed in patients with insult localization in carotid region concerning the brain infarct in the invertebrobasilar system. At the favourable course of disease the gradual decrease of the nucleinic acids' level and the nucleases activity in the studied fluids were observed.

The A8344G mutation in mitochondrial DNA associated with stroke-like episodes and gastrointestinal dysfunction

We report an unusual case of encephalo-entero-myopathy associated with the A8344G mutation in the tRNA(Lys) gene of mitochondrial DNA (mtDNA). This patient had mitochondrial myopathy, multiple lipomatosis, mild hearing loss, stroke-like episodes, and paralytic ileus, but she lacked the canonical clinical features of MERRF, myoclonus, epilepsy, or ataxia. We conducted genetic, biochemical, histochemical, and immunohistochemical studies in skeletal muscle, brain, intestine, and lipoma tissue. The mutation was abundant in all tissues, and cytochrome c oxidase (COX) activity was selectively decreased in brain and small intestine. COX deficiency was also documented histochemically and immunohistochemically in the small intestine, suggesting that mitochondrial dysfunction played a role in the pathogenesis of paralytic ileus. This case illustrates an unusual and dramatic clinical phenotype of the A8344G mutation, characterized by stroke-like episodes and acute ileus.

Evaluation of enzymes in serum and cerebrospinal fluid in cases of stroke

Levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatine kinase (CK) were estimated in serum and cerebrospinal fluid of 25 patients of stroke, and were correlated with severity of disease. 21 (84%) patients had ischemic stroke and four (16%) had hemorrhagic stroke. Serum and CSF AST levels were significantly elevated in the study group. The rise in CSF AST was more in the hemorrhagic subtype than in the ischemic subtype. Serum ALT and CSF LDH levels were also significantly elevated in patients with ischemic stroke. None of the enzyme levels were related to the severity of disease as assessed by the Glasgow coma scale.

Role of p38 and p44/42 mitogen-activated protein kinases in microglia

Although microglial cells are thought to play a beneficial role in the regeneration and plasticity of the central nervous system (CNS), recent studies have indicated that at least some molecules released by microglia may be harmful in acute brain insults and neurodegenerative diseases. Therefore, the pathways mediating the synthesis and release of these neurotoxic compounds are of importance. p38 and p44/42 families of mitogen-activated protein kinases (MAPKs) in microglia respond strongly to various extracellular stimuli, such as ATP, thrombin, and beta-amyloid, a peptide thought to be responsible for the neuropathology in Alzheimer's disease. In this review we describe in vivo evidence implicating that p38 and p44/42 MAPKs may play a critical role in harmful microglial activation in acute brain injury, such as stroke, and in more chronic neurodegenerative diseases, such as Alzheimer's disease. We also clarify the extracellular signals responsible for activation of p38 and p44/42 MAPK in microglia and review the responses so far reported to be mediated by these kinases.

Cyclooxygenase-1 gene knockout does not alter middle cerebral artery occlusion in a mouse stroke model

Cyclooxygenase (COX) is crucial in inflammation; COX-1 is constitutional, and COX-2 is inducible. In this study, neurological function and infarct volume were evaluated at 24 h after permanent endovascular middle cerebral artery occlusion (MCAO) in both COX-1-gene knockout (homozygous or heterozygous) and wide-type mice. Similar infarct volumes and neurological deficits were seen among mice of different genotypes. There was no difference among the groups in arterial blood pressure and regional cerebral blood flow during the first 30 min of ischemia. Our results failed to confirm the harmful effect of losing COX-1 activity due to gene knockout in a permanent endovascular MCAO mouse stroke model.

The therapeutic potential of poly(ADP-ribose) polymerase inhibitors

Poly(ADP-ribose) polymerase-1 (PARP-1) is a member of the PARP enzyme family consisting of PARP-1 and several recently identified novel poly(ADP-ribosylating) enzymes. PARP-1 is an abundant nuclear protein functioning as a DNA nick-sensor enzyme. Upon binding to DNA breaks, activated PARP cleaves NAD(+) into nicotinamide and ADP-ribose and polymerizes the latter onto nuclear acceptor proteins including histones, transcription factors, and PARP itself. Poly(ADP-ribosylation) contributes to DNA repair and to the maintenance of genomic stability. On the other hand, oxidative stress-induced overactivation of PARP consumes NAD(+) and consequently ATP, culminating in cell dysfunction or necrosis. This cellular suicide mechanism has been implicated in the pathomechanism of stroke, myocardial ischemia, diabetes, diabetes-associated cardiovascular dysfunction, shock, traumatic central nervous system injury, arthritis, colitis, allergic encephalomyelitis, and various other forms of inflammation. PARP has also been shown to associate with and regulate the function of several transcription factors. Of special interest is the enhancement by PARP of nuclear factor kappa B-mediated transcription, which plays a central role in the expression of inflammatory cytokines, chemokines, adhesion molecules, and inflammatory mediators. Herein we review the double-edged sword roles of PARP in DNA damage signaling and cell death and summarize the underlying mechanisms of the anti-inflammatory effects of PARP inhibitors. Moreover, we discuss the potential use of PARP inhibitors as anticancer agents, radiosensitizers, and antiviral agents.

Role of superoxide dismutases in oxidative damage and neurodegenerative disorders

In recent years, oxidative stress has been implicated in a variety of degenerative processes, diseases, and syndromes. Some of these include atherosclerosis, myocardial infarction, stroke, and ischemia/reperfusion injury; chronic and acute inflammatory conditions such as wound healing; central nervous system disorders such as forms of familial amyotrophic lateral sclerosis (ALS) and glutathione peroxidase-linked adolescent seizures; Parkinson's disease and Alzheimer's dementia; and a variety of other age-related disorders. Among the various biochemical events associated with these conditions, emerging evidence suggests the formation of superoxide anion and expression/activity of its endogenous scavenger, superoxide dismutase (SOD), as a common denominator. This review summarizes the function of SOD under normal physiological conditions as well as its role in the cellular and molecular mechanisms underlying oxidative tissue damage and neurological abnormalities. Experimental evidence from laboratory animals that either overexpress (transgenics) or are deficient (knockouts) in antioxidant enzyme/protein levels and the genetic SOD mutations observed in some familial cases of ALS are also discussed.

Role of superoxide dismutases in oxidative damage and neurodegenerative disorders

In recent years, oxidative stress has been implicated in a variety of degenerative processes, diseases, and syndromes. Some of these include atherosclerosis, myocardial infarction, stroke, and ischemia/reperfusion injury; chronic and acute inflammatory conditions such as wound healing; central nervous system disorders such as forms of familial amyotrophic lateral sclerosis (ALS) and glutathione peroxidase-linked adolescent seizures; Parkinson's disease and Alzheimer's dementia; and a variety of other age-related disorders. Among the various biochemical events associated with these conditions, emerging evidence suggests the formation of superoxide anion and expression/activity of its endogenous scavenger, superoxide dismutase (SOD), as a common denominator. This review summarizes the function of SOD under normal physiological conditions as well as its role in the cellular and molecular mechanisms underlying oxidative tissue damage and neurological abnormalities. Experimental evidence from laboratory animals that either overexpress (transgenics) or are deficient (knockouts) in antioxidant enzyme/protein levels and the genetic SOD mutations observed in some familial cases of ALS are also discussed.

Sphingomyelinase and ceramide analogs induce vasoconstriction and leukocyte-endothelial interactions in cerebral venules in the intact rat brain: Insight into mechanisms and possible relation to brain injury and stroke

This study was designed to test the hypothesis that the sphingomyelin-ceramide signaling pathway may be important in proinflammatory-like responses in the intact brain. Effects of neutral sphingomyelinase (N-SMase), ceramide analogs, phosphorylcholine and ceramide metabolites were studied on rat brain cerebral (cortical) venule lumen sizes, leukocyte rolling, velocity and endothelial cell wall adhesion, microvessel permeability, microvessel rupture and focal hemorrhages using in vivo high resolution TV microscopy. Perivascular and close intra-arterial administration of N-SMase, C(2)-, C(8)-, and C(16)-ceramide, but not either phosphorylcholine, C(6)-ceramide, nervonic (C(24):1) ceramide, lignoceric (C(24):0) ceramide, C(8)-ceramide-1-phosphate, glucosylceramide or 1-0-acylceramide, resulted in potent, concentration-dependent constriction (and spasm) of cortical venules, followed by increased leukocyte rolling, decreased leukocyte velocities, increased leukocyte-endothelial wall adhesion, increased venular wall permeability, postcapillary venule rupture and, often, micro-hemorrhaging at high concentrations; angiotensin II, serotonin and PGF(2alpha) didn't demonstrate these characteristics. Pretreatment with either one of three different antioxidants, including inhibitors of NF-kappaB activation, or two different Ca(2+) channel blockers either prevented or attenuated the adverse venular effects of N-SMase and the ceramides. Likewise, pretreatment with either a PKCalpha-beta antagonist or a MAP kinase antagonist also attenuated the adverse venular effects. These results suggest that N-SMase and several ceramides can result in potent venular cerebrovasospasm, leukocyte-endothelial chemoattraction, and microvessel wall permeability changes in the intact rat brain. These proinflammatory-like actions suggest that N-SMase and ceramides could produce brain-vascular damage by reperfusion injury triggering lipid peroxidation, release of reactive oxygen species and activation of diverse signaling pathways: PKCalpha-beta isozymes, MAP kinase and NF-kappaB.

Rosuvastatin, a new HMG-CoA reductase inhibitor, upregulates endothelial nitric oxide synthase and protects from ischemic stroke in mice

HMG-CoA reductase inhibitors (statins) are cholesterol-lowering drugs and reduce the risk of myocardial infarction and stroke. In this study we investigated whether rosuvastatin, a new, potent HMG-CoA reductase inhibitor, upregulates endothelial nitric oxide (NO) expression and activity and protects from cerebral ischaemia in mice. Endothelial cells in culture and 129/SV mice were chronically treated with rosuvastatin. The expression and activity of endothelial NO synthase (eNOS) was determined by reverse-transcriptase polymerase chain reaction (RT-PCR), Western blotting and arginine-citrulline assays. Cerebral ischaemia was induced by occlusion of the middle cerebral artery (MCAo) for 2 h and infarct size was determined after 22 h of reperfusion. Treatment of endothelial cells with rosuvastatin concentration- and time-dependently upregulated eNOS mRNA and protein expression. In aortas of 129/SV wild-type mice, treatment with 0.2, 2, and 20 mg kg(-1) rosuvastatin subcutaneously (s.c.) for 10 days significantly upregulated eNOS mRNA by 50, 142, and 205%, respectively. NOS activity was significantly increased by 75, 145, and 320%, respectively. Stroke volume after 2-h MCAo was reduced by 27, 56, and 50% (for 0.2, 2 and 20 mg kg(-1), respectively). Serum cholesterol and triglygeride levels were not significantly lowered by the treatment. The novel HMG-CoA reductase inhibitor rosuvastatin dose-dependently upregulates eNOS expression and activity and protects from cerebral ischaemia in mice. The effects are independent of changes in cholesterol levels and are equivalent or even superior to the protective effects by simvastatin and atorvastatin in this animal model.

Endothelin A receptor blockade decreases expression of growth factors and collagen and improves matrix metalloproteinase-2 activity in kidneys from stroke-prone spontaneously hypertensive rats

This study hypothesizes that endothelin-1 induces renal damage by increasing expression of growth/inflammatory factors, important in renal fibrosis. Male stroke-prone spontaneously hypertensive rats (SHRSPs) (8-weeks, n = 24) were randomized into three groups: control group, high-salt group (4% NaCl), and salt plus an endothelin A receptor antagonist, BMS 182874 (40 mg/kg/d). After 20 weeks treatment, rats were killed. Messenger RNA (mRNA) expression of renal preproendothelin-1, endothelin A and B receptors, and procollagen I and III was evaluated by reverse transcription polymerase chain reaction. Expression of transforming growth factor (TGF)-beta1 and basic fibroblast growth factor (bFGF) was determined by immunoblotting. Matrix metalloproteinase-2 (MMP-2) activity was measured by zymography. In salt-loaded SHRSPs, preproendothelin-1 mRNA expression was increased 1.6-fold, and endothelin A receptor mRNA expression was decreased (70% of control). Salt-loaded SHRSPs had increased renal expression of TGF-b1 and procollagens. MMP-2 activity was augmented fivefold. BMS decreased (p < 0.01) expression of TGF-beta1, bFGF, and procollagen I and reduced MMP-2 activity. Thus severe hypertension and renal dysfunction in salt-loaded SHRSPs are associated with increased expression of renal endothelin-1, growth factors, and collagen. BMS treatment alleviated these effects, suggesting that nephroprotection by endothelin A receptor blockade is mediated by normalizing expression of growth factors, reducing extracellular matrix deposition, and decreasing MMP activity.

Endothelial nitric oxide synthase pathophysiology after nonocclusive common carotid artery thrombosis in rats

Although vascular dysregulation has been documented in patients with extracranial vascular disease, transient ischemic attacks, and stroke, the pathomechanisms are poorly understood. To model thromboembolic stroke in rats, photochemically induced nonocclusive common carotid artery thrombosis (CCAT) was used to generate a platelet thrombus in the carotid artery of anesthetized rats. After CCAT, platelet aggregates break off the thrombus, travel to the distal cerebral vasculature, damage blood vessels, and cause small infarctions. The authors hypothesized that deficits in the endothelial nitric oxide synthase (eNOS) pathway may be responsible for vascular dysfunction after embolic stroke. To examine the functional status of the eNOS system, they measured eNOS-dependent dilation after CCAT by applying acetylcholine through a cranial window over the middle cerebral artery. The authors also measured eNOS mRNA and protein in the middle cerebral artery to determine whether functional changes were caused by alterations in expression. eNOS-dependent dilation was reduced at 6 hours, elevated at 24 hours, and returned to baseline 72 hours after CCAT. Endothelial nitric oxide synthase mRNA increased at 2 hours and was followed by a rise in protein 24 hours after CCAT. Changes in the eNOS system may account for some of the observed vascular deficits in patients with cerebrovascular disease.

Inflammatory response and glutathione peroxidase in a model of stroke

Stroke is one of the leading causes of death in major industrial countries. Many factors contribute to the cellular damage resulting from ischemia/reperfusion (I/R). Experimental data indicate an important role for oxidative stress and the inflammatory cascade during I/R. We are testing the hypothesis that the mechanism of protection against I/R damage observed in transgenic mice overexpressing human antioxidant enzymes (particularly intracellular glutathione peroxidase) involves the modulation of inflammatory response as well as reduced sensitivity of neurons to cytotoxic cytokines. Transgenic animals show significant reduction of expression of chemokines, IL-6, and cell death-inducing ligands as well as corresponding receptors in a focal cerebral I/R model. Reduction of DNA binding activity of consensus and potential AP-1 binding sites in mouse Fas ligand promoter sequence was observed in nuclear extracts from transgenic mice overexpressing intracellular glutathione peroxidase compared with normal animals following I/R. This effect was accompanied by modulation of the c-Jun N-terminal kinase/stress-activated protein kinase pathway. Cultured primary neurons from the transgenic mice demonstrated protection against hypoxia/reoxygenation injury as well as cytotoxicity after TNF-alpha and Fas ligand treatment. These results indicate that glutathione peroxidase-sensitive reactive oxygen species play an important role in regulation of cell death during cerebral I/R by modulating intrinsic neuronal sensitivity as well as brain inflammatory reactions.

Creatine kinase-MB elevation after stroke is not cardiac in origin: comparison with troponin T levels

BACKGROUND AND PURPOSE

Creatine kinase-MB (CK-MB) increases in some patients with stroke, with no clear evidence of an acute coronary syndrome. Its elevations have been suggested to represent a biological marker for stroke-related myocardial injury. Troponin T has superior sensitivity and specificity to CK-MB in revealing minor myocardial injury. Therefore, we studied troponin T levels after stroke to determine whether troponin T increases in parallel to CK-MB.

METHODS

We made daily measurements of CK-MB, myoglobin, total creatine kinase (total CK), and troponin T levels up to day 5 in 32 patients with large hemispheric infarction and with no history of coronary heart disease. The daily enzyme levels were compared with those of a control group of 22 patients with neurological diseases other than stroke.

RESULTS

Serum CK-MB, myoglobin, and total CK levels were elevated above the cutoff value in 11, 26, and 20 patients with stroke, respectively. These enzyme levels gradually increased within the first 3 days and declined afterward. Troponin T did not exceed the reference range in any patients. One patient had elevated myoglobin and 3 had elevated total CK in the control group. The difference between groups was significant for CK-MB, myoglobin, and total CK at various time points.

CONCLUSIONS

Troponin T, a more specific biochemical marker of myocardial injury, does not increase after stroke. Normal troponin T along with elevated CK-MB signifies that CK-MB is not the biological marker for myocytolysis. CK-MB elevations in stroke patients are likely to be noncardiac in origin.