Longitudinal, Quantitative, Multimodal MRI Evaluation of Patients With Intracerebral Hemorrhage Over the First Year

In most patients with intracerebral hemorrhage (ICH), the hematoma and perihematomal area decrease over the subsequent months but patients continue to exhibit neurological impairments. In this serial imaging study, we characterized microstructural and neurophysiological changes in the ICH-affected brain tissues and collected the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Score (mRS), two clinical stroke scale scores. Twelve ICH patients were serially imaged on a 3T MRI at 1, 3, and 12 months (M) after injury. The hematoma and perihematomal volume masks were created and segmented using FLAIR imaging at 1 month which were applied to compute the susceptibilities (χ), fractional anisotropy (FA), mean diffusivity (MD), and cerebral blood flow (CBF) in the same tissues over time and in the matching contralesional tissues. At 3 M, there was a significant (p < 0.001) reduction in hematoma and perihematomal volumes. At 1 M, the χ, FA, and CBF were decreased in the perihematomal tissues as compared to the contralateral side, whereas MD increased. In the hematomal tissues, the χ increased whereas FA, MD, and CBF decreased as compared to the contralesional area at 1 M. Temporally, CBF in the hematoma and perihematomal tissues remained significantly (p < 0.05) lower compared with the contralesional areas whereas MD in the hematoma and χ in the perihematomal area increased. The NIHSS and mRS significantly correlated with hematoma and perihematomal volume but not with microstructural integrity. Our serial imaging studies provide new information on the long-term changes within the brain after ICH and our findings may have clinical significance that warrants future studies.

Intraventricular hemorrhage: Anatomic relationships and clinical implications

BACKGROUND

Spontaneous intracerebral hemorrhage (ICH) is frequently associated with intraventricular hemorrhage (IVH), which is an independent predictor of poor outcome. The purpose of this study was to examine the relationship between ICH volume and anatomic location to IVH, and to determine if ICH decompression into the ventricle is truly beneficial.

METHODS

We retrospectively analyzed the CT scans and charts of all patients with ICH admitted to our stroke center over a 3-year period. Outcome data were collected using our prospective stroke registry.

RESULTS

We identified 406 patients with ICH. A total of 45% had IVH. Thalamic and caudate locations had the highest IVH frequency (69% and 100%). ICH volume and ICH location were predictors of IVH (p < 0.001). Within each location, decompression ranges (specific volume ranges where ventricular rupture tends to occur) were established. Patients with IVH were twice as likely to have a poor outcome (discharge modified Rankin scale of 4 to 6) (OR 2.25, p = 0.001) when compared to patients without IVH. Caudate location was associated with a good outcome despite 100% incidence of IVH. Spontaneous ventricular decompression was not associated with better outcome, regardless of parenchymal volume reduction (p = 0.72).

CONCLUSIONS

Intraventricular hemorrhage (IVH) occurs in nearly half of patients with spontaneous intracerebral hemorrhage (ICH) and is related to ICH volume and location. IVH is likely to occur within the "decompression ranges" that take into account both ICH location and volume. Further, spontaneous ventricular decompression does not translate to better clinical outcome. This information may prove useful for future ICH trials, and to the clinician communicating with patients and families.

Altered PPARgamma expression and activation after transient focal ischemia in rats

Stroke is a devastating disease with limited treatment options. Recently, we found that the peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists troglitazone and pioglitazone reduce injury and inflammation in a rat model of transient cerebral ischemia. The mechanism of this protection is unclear, as these agents can act through PPAR-gamma activation or through PPAR-gamma-independent mechanisms. Therefore, we examined PPAR-gamma expression, DNA binding and transcriptional activity following stroke. In addition, we used a PPAR-gamma antagonist, T0070907, to determine the role of PPAR-gamma during ischemia. Using immunohistochemical techniques and real-time PCR, we found low levels of PPAR-gamma mRNA and PPAR-gamma immunoreactivity in nonischemic brain; however, PPAR-gamma expression dramatically increased in ischemic neurons, peaking 24 h following middle cerebral artery occlusion. Interestingly, we found that in both vehicle- and agonist-treated brains, DNA binding was reduced in the ischemic hemisphere relative to the contralateral hemisphere. Expression of a PPAR-gamma target gene, lipoprotein lipase, was also reduced in ischemic relative to nonischemic brain. Both DNA binding and lipoprotein lipase expression were increased by the addition of the PPAR-gamma agonist rosiglitazone. Finally, we found that rosiglitazone-mediated protection after stroke was reversed by the PPAR-gamma antagonist T0070907. Interestingly, infarction size was also increased by T0070907 in the absence of PPAR-gamma agonist, suggesting that endogenous PPAR-gamma ligands may mitigate the effects of cerebral ischemia.

Early overuse and disuse of the affected forelimb after moderately severe intraluminal suture occlusion of the middle cerebral artery in rats

We have previously shown that early forced overuse of the affected forelimb worsens outcome following moderately severe transient focal cortical ischemic stroke in rats using a distal middle cerebral artery occlusion (MCAo) model. This effect may be site-dependent, because we have also found that early forced use of the affected limb after unilateral 6-OHDA induced degeneration of ascending nigrostriatal dopamine neurons markedly enhanced functional outcome and is neuroprotective. The present study examines the effects of early overuse and disuse following a moderately severe proximal MCAo model, by means of intraluminal suture occlusion. Ischemia was produced in male Long-Evans rats with 60 min of occlusion, or sham surgery was performed. Early overuse or disuse of the affected forelimb was forced by immobilizing either the ipsilateral or contralateral forelimb, respectively, in a plaster cast or the animal was left uncasted. Casts were removed on day 10 and sensorimotor testing was performed weekly during days 17-38. Animals were sacrificed on day 45 and brains were fixed for later cresyl violet staining. The MCAo+contralateral cast group performed worse than all other groups on tests of forelimb sensorimotor function. All MCAo groups regardless of cast condition had significant atrophy of the ischemic striatum, but there was no significant atrophy of the ischemic cortex in any group. Forced disuse, but not overuse, of the affected forelimb immediately following proximal ischemia using the intraluminal suture model has detrimental effects on functional outcome, without exaggerating anatomical damage. The effects of disuse and overuse during the first 10 days after stroke differ depending on cortical or subcortical involvement.

Selective up-regulation of I kappaB-alpha in ischemic penumbra following focal cerebral ischemia

Activation of transcription factor NF-kappaB plays a critical role in immune, inflammatory and cell death responses. In resting cells, NF-kappaB is sequestrated in the cytoplasm in an inactive form through its association with inhibitory proteins, I kappaB (e.g.I kappaB-alpha). In response to cell activation, I kappaB is degraded causing release of active NF-kappaB. Active NF-kappaB translocates into the nucleus leading to activation of transcription that may have a profound effect on cell survival, including that after ischemic stroke. Here, using Western blot analysis, we show that immunoreactivity to the major subunit of NF-kappaB, p65, as well as to the inhibitory subunit I kappaB-alpha is equally markedly decreased in the ischemic core after transient middle cerebral and common carotid artery occlusion in rats. In contrast, penumbral regions display no change in p65, and significant increase in I kappaB-alpha immunoreactivity, as compared to non-ischemic areas. In these penumbral regions with elevated I kappaB-alpha immunoreactivity, we find reduced cytosolic and increased nuclear I kappaB-alpha staining of neurons, as determined by immunohistochemistry. Altogether, these results suggest that an altered ratio between activating and inhibitory NF-kappaB pathways mediated through I kappaB-alpha may play an important role in survival of the ischemic penumbra.

Early exclusive use of the affected forelimb after moderate transient focal ischemia in rats : functional and anatomic outcome

BACKGROUND AND PURPOSE

Previous work by researchers in our laboratory has shown that in the rat, the exclusive use of the affected forelimb during an early critical period exaggerates lesion volume and retards functional recovery after electrolytic lesions of the forelimb sensorimotor cortex. In the present study, we examined the effects of exclusive use of the affected forelimb after middle cerebral artery occlusion (MCAO).

METHODS

Ischemia of moderate severity was produced in male Long-Evans rats through 45 minutes of occlusion of the left middle cerebral and both common carotid arteries. Exclusive use of either the affected or unaffected forelimb was forced through immobilization of either the ipsilateral (MCAO+ipsi) or contralateral (MCAO+contra) forelimb, respectively, for 10 days in a plaster cast, or the animal was left uncasted (MCAO+nocast). Sham surgeries were performed, and animals were also casted for 10 days or left uncasted. Sensorimotor testing was performed during days 17 to 38. At the end of sensorimotor testing, cognitive performance was tested with use of the Morris water maze. In a separate experiment, temperatures and corticosterone levels were measured during the 10-day period after 45-minute ischemia and casting.

RESULTS

The MCAO+ipsi group performed worse on sensorimotor tasks than the MCAO+contra, MCAO+nocast, and sham groups. Infarct volume was significantly larger in the MCAO+ipsi group than in the sham and MCAO+contra groups but not in the MCAO+nocast group. No group differences were found with the Morris water maze, and no group differences were found in either temperature or plasma corticosterone level.

CONCLUSIONS

The exclusive use of the affected forelimb immediately after focal ischemia has detrimental effects on sensorimotor function that cannot be attributed to hyperthermia or stress.

Interplay between the gamma isoform of PKC and calcineurin in regulation of vulnerability to focal cerebral ischemia

Protein phosphorylation and dephosphorylation mediated by protein kinases and protein phosphatases, respectively, represent essential steps in a variety of vital neuronal processes that could affect susceptibility to ischemic stroke. In this study, the role of the neuron-specific gamma isoform of protein kinase C (gammaPKC) in reversible focal ischemia was examined using mutant mice in which the gene for gammaPKC was knocked-out (gammaPKC-KO). A period of 150 minutes of unilateral middle cerebral artery and common carotid artery (MCA/CCA) occlusion followed by 21.5 hours of reperfusion resulted in significantly larger (P < 0.005) infarct volumes (n = 10; 31.1+/-4.2 mm3) in gammaPKC-KO than in wild-type (WT) animals (n = 12; 22.6+/-7.4 mm3). To control for possible differences related to genetic background, the authors analyzed Balb/cJ, C57BL/6J, and 129SVJ WT in the MCA/CCA model of focal ischemia. No significant differences in stroke volume were detected between these WT strains. Impaired substrate phosphorylation as a consequence of gammaPKC-KO might be corrected by inhibition of protein dephosphorylation. To test this possibility, gammaPKC-KO mice were treated with the protein phosphatase 2B (calcineurin) inhibitor, FK-506, before ischemia. FK-506 reduced (P < 0.008) the infarct volume in gammaPKC-KO mice (n = 7; 24.6+/-4.6 mm3), but at this dose in this model, had no effect on the infarct volume in WT mice (n = 7; 20.5+/-10.7 mm3). These results indicate that gammaPKC plays some neuroprotective role in reversible focal ischemia.

Combination of low dose ethanol and caffeine protects brain from damage produced by focal ischemia in rats

Caffeine and ethanol are two commonly overused psychoactive dietary components. The purpose of this study was to assess the effects of acute, chronic, oral (p.o.) and intravenous (i.v.) caffeine, ethanol and their combination on infarct volume following focal ischemia in rats. Rats received treatment either p.o. 3 h and 1 h before, or by i.v. infusion for 2.5 h beginning 30-180 min after, ischemia. There were six acute treatment groups. (1) oral dH2O (control); (2) oral caffeine (10 mg/kg); (3) oral ethanol (0.65 g/kg total); (4) oral ethanol plus caffeine; (5) intravenous saline; and (6) intravenous ethanol (0.65 g/kg) plus caffeine (10 mg/kg) in saline. A 7th group received oral ethanol plus caffeine for three weeks prior to ischemia. After 3 h of left MCA/CCA occlusion and 24 h reperfusion, infarct volume was determined. Control animal infarct volume was 102.4+/-42.0 mm3. Oral caffeine alone had no effect (122.4+/-30.2 mm3). Oral ethanol alone exacerbated infarct volume (177.2+/-27.8 mm3). Oral caffeine plus ethanol almost entirely eliminated the damage (17.89+/-10.41 mm3). When i.v. treatment with ethanol plus caffeine was initiated at 30, 60, 90 and 120 minutes post-ischemia the infarct volume was reduced by 71.7%, 49.8%, 64.8% and 47.1%, respectively. Chronic daily oral ethanol plus caffeine prior to ischemia eliminated the neuroprotection seen with acute treatment. These studies indicate that ethanol, which by itself aggravates cerebral ischemia, and caffeine, when combined together immediately before or for 2 h after focal stroke, reduces ischemic damage.

Nuclear factor-kappaB and cell death after experimental intracerebral hemorrhage in rats

BACKGROUND AND PURPOSE

Nuclear factor-kappaB (NF-kappaB) is a ubiquitous transcription factor that, when activated, translocates to the nucleus, binds to DNA, and promotes transcription of many target genes. Its activation has been demonstrated in chronic inflammatory conditions, cerebral ischemia, and apoptotic cell death. The present study evaluated the presence and activation of NF-kappaB in relation to cell death surrounding intracerebral hemorrhage (ICH).

METHODS

Striatal ICH was induced in rats by the double blood injection method. Animals were killed 2, 8, and 24 hours and 4 days after ICH. To examine changes in NF-kappaB protein, Western blot was performed on brain extract. We determined NF-kappaB activity using electrophoretic mobility shift assay (EMSA) and immunohistochemistry, using an antibody that only recognizes active NF-kappaB. DNA fragmentation was detected with terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling (TUNEL) staining.

RESULTS

Western blot analysis of the NF-kappaB p65 subunit showed that there was no difference in p65 protein levels in the control, 2-hour, 8-hour, or 24-hour groups. However, ipsilateral perilesional samples from the 4-day group revealed a 1.8- to 2.5-fold increase compared with the contralateral hemisphere. Western blotting showed no differences in the inhibitor of NF-kappaB, IkappaBalpha, in any group. EMSA showed 1.3-, 2.1-, and 3.6-fold increased NF-kappaB activation in the ipsilateral striatum from the 8-hour, 24-hour, and 4-day groups, respectively, compared with the contralateral hemisphere. Immunohistochemistry, in which an activation-dependent anti-NF-kappaB antibody was used, demonstrated perivascular NF-kappaB activation as early as 2 hours after ICH with more generalized activation at 8 hours, in agreement with the EMSA results. NF-kappaB activation colocalized to cells containing fragmented DNA measured by TUNEL.

CONCLUSIONS

The present study suggests a relationship between NF-kappaB and the pathobiology of perilesional cell death after ICH.

Neurofilament proteolysis after focal ischemia; when do cells die after experimental stroke?

To determine the occurrence and time-course of presumably irreversible subcellular damage after moderate focal ischemia, rats were subjected to 1, 3, 6, 9, or 24 hours of permanent unilateral middle cerebral and common carotid occlusion or 3 hours of reversible occlusion followed by 3, 6, or 21 hours of reperfusion. The topography and the extent of damage were analyzed with tetrazolium staining and immunoblot using an antibody capable of detecting breakdown of neurofilament. Neurofilament proteolysis began after 3 hours in the infarct core but was still incomplete in penumbral regions up to 9 hours. Similarly, tetrazolium-staining abnormalities were observed in the core of 50% of animals after 3 hours of ischemia. At 6 hours of permanent ischemia, infarct volume was maximal, and further prolongation of occlusion to 9 or 24 hours did not increase abnormal tetrazolium staining. In contrast to permanent ischemia and in agreement with the authors' previous demonstration of "reperfusion injury" in this model, prolongation of reperfusion from 3 hours to 6 and 21 hours after 3 hours of reversible occlusion gradually augmented infarct volume by 203% and 324%, respectively. Neurofilament proteolysis initiated approximately 3 hours after ischemia was quantitatively greatest in the core and extended during reperfusion to incorporate penumbra with a similar time course to that of tetrazolium abnormalities. These data demonstrate that, at least as measured by neurofilament breakdown and mitochondrial failure, extensive cellular damage is not present in penumbral regions for up to 9 hours, suggesting the potential for rescuing these regions by appropriate and timely neuroprotective strategies.

The effect of prolonged imipramine and electroconvulsive shock treatment on calcium/calmodulin-dependent protein kinase II in the hippocampus of rat brain

The phosphorylation of substrate proteins by protein kinases plays a key role in signal transduction and function of neurons. Protein kinases have been associated with several physiological and pathological states including depression. The aim of the present study was to investigate the effect of imipramine and electroconvulsive treatment (ECS), both clinically effective treatments of depression, on the activity of calcium/calmodulin dependent protein kinase II (CaM-KII) in the hippocampus. Our results indicate that repeated (but not acute) imipramine and ECS administration significantly decreased CaM-KII activity by 65 and 70%, respectively, in the soluble fractions from hippocampus. This decreased enzyme activity was accompanied by a proportional decrease (60-70%) of the amount of a-CaM-KII in the same fraction. A single and repeated administration of imipramine produced a significant increase in the activity of CaM-KII (50 and 337%, respectively) in the particulate fraction from hippocampus. Similarly, a single and repeated ECS produced an increase in the enzyme activity by 22 and 240%, respectively. The amount of a-CaM-KII in the particulate fraction was not significantly affected by repeated antidepressant administration. It is postulated that changes in CaM-KII activity following chronic antidepressant treatment might represent and important step in expression of its antidepressive action.

Reperfusion injury: demonstration of brain damage produced by reperfusion after transient focal ischemia in rats

During reperfusion after ischemia, deleterious biochemical processes can be triggered that may antagonize the beneficial effects of reperfusion. Research into the understanding and treatment of reperfusion injury (RI) is an important objective in the new era of reperfusion therapy for stroke. To investigate RI, permanent and reversible unilateral middle cerebral artery/common carotid artery (MCA/CCA) occlusion (monitored by laser Doppler) of variable duration in Long-Evans (LE) and spontaneously hypertensive (SH) rats and unilateral MCA and bilateral CCA occlusion in selected LE rats was induced. In LE rats, infarct volume after 24 hours of permanent unilateral MCA/CCA occlusion was 31.1 +/- 34.6 mm3 and was only 28% of the infarct volume after 120 to 300 minutes of reversible occlusion plus 24 hours of reperfusion, indicating that 72% of the damage of ischemia/reperfusion is produced by RI. When reversible ischemia was prolonged to 480 and 1080 minutes, infarct volume was 39.6 mm3 and 16.6 mm3, respectively, being indistinguishable from the damage produced by permanent ischemia and significantly smaller than damage after 120 to 300 minutes of ischemia. Reperfusion injury was not seen in SH rats or with bilateral CCA occlusion in LE rats, in which perfusion is reduced more profoundly. Reperfusion injury was ameliorated by the protein synthesis inhibitor cycloheximide or spin-trap agent N-tert-butyl-alpha-phenylnitrone pretreatment.

Citicoline for treatment of experimental focal ischemia: histologic and behavioral outcome

We evaluated the effect of chronic administration of CDP-choline, an intermediate of phospholipid synthesis, on outcome from middle cerebral artery occlusion, ranging from 30 to 120 min in duration in spontaneously hypertensive rats. Rats were randomly assigned to either CDP-choline 500 mg kg-1 or saline. CDP-choline treatment was initiated by intraperitoneal injection 15 min after the onset of ischemia and continued once a day for 14 days. Morphologic damage and behavioral dysfunction (motor and sensorimotor performance) were evaluated, and the maximal morphologic damage (Volmax), maximal behavioral dysfunction (BDmax) as well as the duration of ischemia producing half-maximal morphologic damage (T50) or behavioral dysfunction (BD50) were calculated using a curve-fitting program (ALLFIT). Ischemia in control animals produced a Volmax of 103.3 +/- 13.6 mm3. CDP-choline did not affect this value (Volmax of 101.6 +/- 11.4 mm3). However, CDP-choline significantly extended the T50 from 38.3 +/- 5.9 to 60.5 +/- 4.3 min (p < 0.05). Similar to the morphologic outcome, CDP-choline had no effect on BDmax but significantly extended BD50 from 41.9 +/- 4.6 to 72.9 +/- 24.5 min (p < 0.05). Our results suggest that the effectiveness of CDP-choline is greater in animals demonstrating submaximal ischemic injury which in this model is produced by 30-75 min of ischemia (effect on T50 and BD50), than in animals suffering maximal ischemic injury produced by ischemia longer than 75 min (no effect on Volmax and BDmax). These results may reflect a threshold of biological membrane damage within which CDP-choline is able to restore phospholipid content/arrangement and retain membrane integrity.

Combined neuroprotection and reperfusion therapy for stroke. Effect of lubeluzole and diaspirin cross-linked hemoglobin in experimental focal ischemia

BACKGROUND AND PURPOSE

In search of a better treatment for acute ischemic stroke, we evaluated the use of lubeluzole and hemodilution with diaspirin cross-linked hemoglobin (DCLHb) therapy to test whether treatment with two complementary acting compounds provides more potent protection than either treatment alone.

METHODS

We used unilateral reversible middle cerebral artery (MCA) and common carotid artery (CCA) occlusion of various durations in Long-Evans rats to produce ischemic cortical lesions. We calculated the average maximal lesion volume (Volmax) and the time required to produce half maximal lesion size (T50) in control animals (n = 31) and evaluated the effects on cerebral perfusion and infarct size of treatment with lubeluzole (n = 23), hemodilution (to 30% hematocrit) with albumin (n = 17) or DCLHb (n = 23), and combined lubeluzole + DCLHb therapy initiated 15 minutes after MCA/CCA occlusion.

RESULTS

The Volmax produced by MCA/CCA occlusion in control animals was 138.5 +/- 7.7 mm3, and T50 was 98.5 +/- 10.2 minutes. Lubeluzole alone reduced Volmax by 53% with no significant effect on T50. In contrast to lubeluzole, DCLHb hemodilution prolonged T50 by 68% with no significant effect on Volmax. Prolongation of T50 by DCLHb was not due to hemodilution itself, since a similar degree of hemodilution with albumin had no effect. Finally, combined lubeluzole+DCLHb rescued 72% of the tissue and augmented the effect of lubeluzole alone by 40% (Volmax, 66.3 +/- 13.0 versus 39.4 +/- 12.2 mm3) while prolonging T50 by 31%.

CONCLUSIONS

Combination therapy for acute stroke using compounds with complementary action can result in more complete attenuation of neuronal damage and demonstrates the possible clinical utility of combined neuroprotective and reperfusion therapies.

An alternative method for the quantitation of neuronal damage after experimental middle cerebral artery occlusion in rats: analysis of behavioral deficit

We tested the hypothesis that increasing durations of focal ischemia that have been shown to result in enlargement of cortical infarct will be associated with progression of behavioral dysfunction that can be measured by a battery of tests sufficiently sensitive and reproducible to detect a positive effect of pharmacotherapy. Untreated or N-methyl-D-aspartate receptor antagonist (CNS-1102)-treated spontaneously hypertensive rats underwent 45, 60, 90, or 120 min of tandem middle cerebral and common carotid artery occlusion followed by reperfusion. We then evaluated the extent of damage and its recovery for up to 21 days using nine behavioral tests aimed at analyzing strength, coordination, and bilateral asymmetry. Also using a graded bioassay that employs a curve-fitting computer program (ALLFIT) to correlate duration of ischemia with degree of behavioral dysfunction, we calculated the average of maximal behavioral dysfunction and duration of ischemia required to produce half-maximal behavioral dysfunction and compared these values in untreated controls with analogous values obtained from animals treated with CNS-1102. Three behavioral tests, forearm flex, tape (somatosensory neutralization), and foot-fault placing, were each separately and combined able to distinguish between the degrees of damage produced by increasing durations of ischemia. The behavioral abnormalities assessed using the tape test were reversible within a week, whereas those using forearm flex or foot-fault tests persisted for at least 21 days. CNS-1102 significantly reduced behavioral dysfunction measured by all three tests. This analysis of behavioral dysfunction represents a useful experimental model to grade efficacy of therapies aimed at protecting the brain from damage produced by acute stroke and might also be used to assess recovery from preexisting ischemic damage.

Treatment of experimental focal ischemia in rats with lubeluzole

Lubeluzole is a neuroprotective compound in the final stages of clinical evaluation. We evaluated the effects of intravenous followed by intraperitoneal doses of lubeluzole on histological outcome after reversible tandem middle cerebral/common carotid artery occlusion in Long-Evans rats, with particular emphasis on the time window of efficacy. Lubeluzole, started 15 min after the onset of ischemia, had no adverse physiological or behavioral effects and reduce maximal infarct volume produced by 120 min or more of arterial occlusion by approximately 50%, from 143.2 +/- 11.8 mm3 (p < 0.05). Lubeluzole did not prolong the duration of middle cerebral artery occlusion which could be tolerated before histological damage occurred. Lubeluzole was still effective if started 30 min after the onset of ischemia (34% reduction of maximal infarct volume; p < 0.05), but not after delays of 60 or 120 min. we conclude that lubeluzole has promise as a neuroprotective drug, particularly for more severe strokes, but must be started very rapidly after the onset of ischemia to be effective.

Inactivation and self-association of Ca2+/calmodulin-dependent protein kinase II during autophosphorylation

The time-dependent loss in enzyme activity associated with the autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaM-kinase) was altered by both pH and ATP concentration. These parameters also influenced the extent to which soluble CaM-kinase undergoes self-association to form large aggregates of sedimentable enzyme. Specifically, autophosphorylation of CaM-kinase in 0.01 mM ATP at pH 6.5 resulted in the formation of sedimentable enzyme and a 70% loss of enzyme activity. Under similar conditions at pH 7.5, the enzyme lost only 30% of its activity, and no sedimentable enzyme was detected. In contrast to 0.01 mM ATP, autophosphorylation of CaM-kinase at pH 6.5 in 1 mM ATP did not result in a loss of activity or the production of sedimentable enzyme, even though the stoichiometry of autophosphorylation was comparable. Electron microscopy studies of CaM-kinase autophosphorylated at pH 6.5 in 0.01 mM ATP revealed particles 100-300 nm in diameter that clustered into branched complexes. Inactivation and self-association of CaM-kinase were influenced by the conditions of autophosphorylation in vitro, suggesting that both the catalytic and physical properties of the enzyme may be sensitive to fluctuations in ATP concentration and pH in vivo.

Ca2+/calmodulin-dependent protein kinase II in postsynaptic densities after reversible cerebral ischemia in rats

Compartmentalization of protein kinases and association of the enzyme with strategic cellular substrates may be important for regulating signal transduction in neurons. Cerebral ischemia produced by transient 20 min occlusion of common carotid and vertebral arteries in rats caused a dramatic (3-fold) increase in Ca2+/Calmodulin-dependent protein kinase II (CaM-KII) in the fraction enriched in postsynaptic density (PSDf), the compartment of the neuron that is involved in signal transduction. This change in compartmentalization was not reversible for up to 24 h after termination of the occlusion and was followed by reduction of CaM-KII to 50% of control content one week after the insult. The observed changes in CaM-KII content did not represent general protein redistribution in PSDf after ischemia since there were no parallel changes in PSDf actin concentration. The redistribution of CaM-KII coincided with gradual (up to 80%) reduction of its activity in PSDf as tested using specific peptide substrate and endogenous CaM-KII substrates. This work provides evidence that ischemia disturbs CaM-KII distribution and activity in PSDf and this may lead to long lasting disruption of signal transduction at the synaptic level.

Ischemia-induced neuronal damage: a role for calcium/calmodulin-dependent protein kinase II

Calcium/calmodulin-dependent protein kinase II (CaM-kinase) is a central enzyme in regulating neuronal processes. Imbalances in the activity and distribution of this enzyme have been reported following in vivo ischemia, and sustained decreases in activity correlate with subsequent neuronal death. In this report, mice that had been rendered deficient in the alpha subunit of CaM-kinase using gene knock-out technology were utilized to determine whether this enzyme is causally related to ischemic damage. Using a focal model of cerebral ischemia, we showed that homozygous knock-out mice lacking the alpha subunit exhibited an infarct volume almost twice that of wild-type litter mates. Heterozygous mice exhibited slightly less damage following ischemia than did homozygous mice, but infarct volumes remained significantly larger than those of wild-type litter mates. We conclude that reduced amounts of the alpha subunit of CaM-kinase predisposes neurons to increased damage following ischemia and that any perturbation that decreases the amount or activity of the enzyme will produce enhanced susceptibility to neuronal damage.

Activity of Ca2+/calmodulin-dependent protein kinase II following ischemia: a comparison between CA1 and dentate gyrus in a hippocampal slice model

Both CA1 and dentate gyrus regions of the hippocampal slice exhibit an irreversible loss of synaptic transmission after exposure to in vitro ischemic conditions (buffer without oxygen and glucose). However, after shorter durations of ischemia (8-10 min) the CA1 region shows an irreversible loss of synaptic responses, whereas the dentate gyrus region completely recovers synaptic responses upon reoxygenation. To determine biochemical mechanisms underlying this differential susceptibility, we have examined changes in Ca2+/calmodulin-dependent protein kinase II (CaM-KII) and cyclic AMP-dependent protein kinase activities in homogenates from CA1 and dentate gyrus regions of the hippocampal slice after increasing durations of in vitro ischemia. Time-dependent changes in CaM-KII activities were correlated with changes in electrophysiological responses. CA1 homogenates from slices exposed to 1 min of ischemia showed significant increases in CaM-KII activity, whereas there was no significant change in kinase activity in dentate homogenates after 1 min of ischemia. However, after longer durations of ischemia (5, 10, and 20 min) we found a time-dependent reduction in CaM-KII activity in both CA1 and dentate gyrus regions, whereas no change was detected in cyclic AMP-dependent protein kinase activity. Irreversible depression of CaM-KII activity was seen at shorter durations of ischemia (10 min) in the CA1 region than in dentate region (20 min), which correlated with irreversible effects on synaptic responses. Immunoblot analysis showed that the decrease in CaM-KII activity was not due to degradation of CaM-KII protein.(ABSTRACT TRUNCATED AT 250 WORDS)

Graded bioassay for demonstration of brain rescue from experimental acute ischemia in rats

BACKGROUND AND PURPOSE

This study explored the correlation between duration of focal ischemia and infarct volume in spontaneously hypertensive rats as a measure of outcome after neuroprotective intervention.

METHODS

We used 2,3,5-triphenyltetrazolium chloride staining to discriminate infarcted tissue and calculate infarct volume 24 hours after temporary tandem common carotid/middle cerebral artery occlusion lasting 5 to 150 minutes. We used a graded bioassay described by logistic function and executed by computer program (ALLFIT) to evaluate changes in infarct volume after increasing durations of ischemia. The method allowed us to calculate the maximal infarct volume (Volmax) and the duration of ischemia before reperfusion producing half-maximal infarct size (T50). Hypothermia and the N-methyl-D-aspartate antagonist CNS-1102 begun after the onset of ischemia were tested for their ability to reduce Volmax and prolong T50 as analyzed by ALLFIT.

RESULTS

Volmax was 180.6 +/- 22.4 mm3 and T50 was 45.9 +/- 5.8 minutes in control rats. Hypothermia (30 degrees C) applied during ischemia reduced Volmax by 66 mm3 and extended T50 by 50% (P < .05 for each comparison). CNS-1102, like hypothermia, extended T50 by 44% but did not have an effect on Volmax.

CONCLUSIONS

Analysis of the changes of infarct size after increasing durations of ischemia indicates that although both were protective, the two treatments tested may exhibit different profiles of efficacy. This method of analyzing ischemia-induced damage may be very sensitive for studying the efficacy and possible clinical use of neuronal protective therapies for hyperacute stroke.

Calcium/calmodulin-dependent protein kinase II activity in focal ischemia with reperfusion in rats

BACKGROUND AND PURPOSE

Evidence linking changes in calcium/calmodulin-dependent protein kinase II activity with ischemic cell death has been reported in animal models of global ischemia. The purpose of this study was to delineate the course of these changes after focal ischemia and to clarify the relation of changes in activity of calcium/calmodulin-dependent protein kinase II to the process of ischemic cell death.

METHODS

Change in calcium/calmodulin-dependent protein kinase II activity was evaluated in a rat model of focal ischemia after 5 minutes, 30 minutes, and 1 hour of tandem middle cerebral artery and common carotid artery occlusion both with and without reperfusion.

RESULTS

Calcium/calmodulin-dependent protein kinase II activity was significantly decreased after all three durations of ischemia followed by immediate decapitation compared with sham-operated animals, in both ischemic core and border-zone regions (P < .05 for all groups). Depression of activity occurred in a regionally graded fashion, with the most severe decrease in infarct core and progressively smaller decreases in samples moving out from the center, corresponding to the severity of histological injury later detected in infarct core and border-zone regions. There were only minor differences between the three durations of ischemia in the degree of enzyme depression noted in the more peripheral regions, indicating that the initial decrease in calcium/calmodulin-dependent protein kinase II activity is an early, sensitive marker for an ischemic insult. After reperfusion, the differences between the 5-minute group and longer periods of ischemia widened because of an increase toward baseline in the 5-minute group and a trend toward further decrease in the 30- and 60-minute groups.

CONCLUSIONS

The extreme sensitivity of calcium/calmodulin-dependent protein kinase II to focal ischemia and the parallel temporal and regional changes in its activity to those of more delayed cell injury point to a potential role for this enzyme in the process of excitotoxic injury.

Neuronal protection and preservation of calcium/calmodulin-dependent protein kinase II and protein kinase C activity by dextrorphan treatment in global ischemia

This study analyzed the ability of the N-methyl-D-aspartate receptor antagonist dextrorphan (DX) to prevent neuronal degeneration (analyzed by light microscopy), calmodulin (CaM) redistribution (analyzed by immunocytochemistry) and changes in activity of two major Ca(2+)-dependent protein kinases--calcium/calmodulin-dependent protein kinase II (CaM-KII) and protein kinase C (PKC) (analyzed by specific substrate phosphorylation) after 20 min of global ischemia (four-vessel occlusion model) in rats. DX treatment before and after ischemia significantly protected hippocampal and cortical neurons from neurodegeneration whereas DX posttreatment alone did not have any effect on preservation of neuronal morphology as compared with placebo treatment analyzed 72 h after 20 min of ischemia. Similarly to histological changes, DX exhibited protection against redistribution of CaM observed after ischemia. These changes were detected both in hippocampus as well as in cerebral cortex. Finally, DX administered before ligation of the carotid arteries reduced loss in both CaM-KII and PKC activity evoked by ischemia.

Ca2+/calmodulin-dependent protein kinase II is phosphorylated by protein kinase C in vitro

Protein kinase C (PKC) phosphorylated a synthetic peptide (CBP) that included the Thr-286 phosphorylation sequence and calmodulin binding domain of Ca2+/calmodulin-dependent protein kinase type II (CaM-kinase). Studies with a variety of truncated peptides suggested that the amino acid phosphorylated by PKC was Thr-286, the same amino acid that when autophosphorylated by Ca2+/calmodulin activation of CaM-kinase results in Ca2+/calmodulin-independent activity. These peptide studies also suggested that the C-terminal region of CBP is required to obtain maximal phosphorylation of Thr-286 by PKC. PKC also phosphorylated purified CaM-kinase from rat forebrain. Phosphopeptide analysis by one- and two-dimensional proteolytic maps of autophosphorylated CaM-kinase and CaM-kinase phosphorylated with PKC identified that there are both similar and unique sites phosphorylated. Phosphoamino acid analysis of CaM-kinase phosphorylated by PKC indicated that both Ser and Thr residues were phosphorylated. Even though Thr-286 of CaM-kinase appeared to be phosphorylated by PKC, no Ca2+/calmodulin-independent activity was detected, and, additionally, no significant change in Ca2+/CaM-dependent activation was detected. These results provide the first indication that these two important protein kinases may communicate directly through interenzyme phosphorylation.

Ischemia-induced translocation of Ca2+/calmodulin-dependent protein kinase II: potential role in neuronal damage

The activities of Ca2+/calmodulin (CaM)-dependent, Ca2+/phospholipid-dependent, and cyclic AMP-dependent protein kinases (CaM-KII, PKC, and PKA, respectively) were determined in rat brains after global ischemia. Both CaM-KII and PKC activities were significantly depressed in both hippocampal and cerebral cortical regions of ischemic animals, whereas no change was detected in PKA activity. The loss of CaM-KII activity was more dramatic and more sustained than the loss of PKC activity and correlated with the duration of ischemia. These decreases in enzyme activity were found in both supernatant and pellet fractions from crude homogenates. When the supernatant and pellet were analyzed for the amount of CaM-KII 50-kDa protein, a significant decrease was detected in supernatant fractions that paralleled a gain in the amount of CaM-KII in the pellet. Thus, the loss of CaM-KII activity in the supernatant can be explained by translocation of the enzyme to the pellet. Whether inactivation of CaM-KII occurs during or after the enzyme translocates from the supernatant to the pellet is unknown. Our results indicate that loss in CaM-KII activity parallels neuronal damage associated with ischemia; down-regulation of CaM-KII activity coincided with translocation of the enzyme to the particulate fraction, and it is proposed that this may be, in fact, a mechanism for controlling excessive CaM-KII phosphorylation.

Mutagenesis of Thr-286 in monomeric Ca2+/calmodulin-dependent protein kinase II eliminates Ca2+/calmodulin-independent activity

We have examined the role of Thr-286 autophosphorylation in the autoregulation of Ca2+/calmodulin-dependent protein kinase II. Using site-directed mutagenesis, we have substituted alanine or serine for Thr-286, or isoleucine for Arg-283, in the 50-kDa subunit of the kinase and expressed each protein in bacteria. Activation and autophosphorylation of all four enzymes were stringently dependent on Ca2+/calmodulin, indicating that neither Arg-283 nor Thr-286 is an absolute requirement for the pseudosubstrate inhibition of the enzyme. Autophosphorylation of the Ile-283 or Ala-286 enzyme generated little, if any, Ca2+/calmodulin-independent kinase activity, unlike the parent (Thr-286) or Ser-286 enzyme. The enzymes expressed in bacteria are predominantly monomeric, indicating that the generation of Ca2+/calmodulin-independent activity does not require the cooperative interactions of subunits normally present in the brain holoenzyme.

Functional analysis of Ca2+/calmodulin-dependent protein kinase II expressed in bacteria

The cDNA encoding the 50-kDa subunit of Ca2+/calmodulin (CaM)-dependent protein kinase II from adult rat brain was cloned into the bacterial expression vector pK223-2 and produced in bacteria. Extensive modification of the cDNA was required to express detectable levels of enzyme. The activity of the bacterially expressed kinase was stringently dependent on Ca2+/CaM but did not exhibit cooperative activation kinetics characteristic of the forebrain enzyme and required 10-fold greater amounts of CaM for half-maximal activation. The bacterially expressed enzyme displayed an apparent Km for a synthetic peptide substrate similar to that of the forebrain enzyme (12 and 10 microM, respectively). Limited proteolysis maps of autophosphorylated peptides, and Western blot analysis demonstrated that the bacterially expressed enzyme was structurally and immunologically indistinguishable from the 50-kDa subunit of the rat forebrain holoenzyme. The bacterially expressed enzyme became Ca2+/CaM-independent after Ca2+/CaM-dependent autophosphorylation in a fashion identical to the forebrain enzyme.

Identification of amino acids involved in the sialidase activity of the mumps virus hemagglutinin-neuraminadase protein

We previously described sialidase-deficient variants of the O'Take strain of mumps virus obtained by growth under the selective pressure of the competitive sialidase inhibitor 2-deoxy-2,3-dehydro-N-acetylneuraminic acid (DANA). In this report, we describe the production of a sialidase-deficient variant of the RW strain of mumps virus using an identical selection protocol. The biologic activities of the RW variant, RW(DANA)v1, were identical to those described for O'Take-(DANA)v1 and included a lack of detectable sialidase activity, unchanged hemagglutination activity, and expression of cell-to-cell fusion in infected cell monolayers. Analysis of the structural proteins of each virus by both two-dimensional tryptic peptide mapping and monoclonal antibody binding assays suggested that limited changes occurred in the hemagglutinin-neuraminidase (HN) proteins and that only the HN proteins were altered. The complete nucleotide sequence of the RW(DANA)v1 HN was determined and compared to the HN sequence of the RW parent. Two nucleotide differences accounting for two nonconservative amino acid differences were noted; an lle to a Thr at amino acid 181 and a Gln to Lys at amino acid 261 from RW to RW(DANA)v1, respectively. By comparing the data presented here with those reported for several other paramyxoviruses, we tentatively identify amino acid 181 as a critical residue in the active site of the mumps virus sialidase enzyme.

Sequence determination of the mumps virus HN gene

The hemagglutinin-neuraminidase protein (HN) of mumps virus was purified by immunoaffinity chromatography and fragmented by the combined action of CNBr and trypsin. The resulting peptides were separated by HPLC and sequenced by automated Edman degradation. Using this HN-specific amino acid sequence data, a degenerate oligonucleotide was produced and subsequently used to screen a mumps virus cDNA library to isolate HN-specific clones. The complete nucleotide sequence of the HN gene was determined. The monocistronic HN mRNA is approximately 1900 nucleotides long and encodes a single open reading frame of 582 amino acids. The HN protein has a unique hydrophobic stretch of 19 amino acids at its N-terminus that apparently anchors the protein in the viral envelope. A comparison of the mumps virus HN protein sequence with the sequences of the other known paramyxovirus HNs indicates that mumps virus is most closely related to SV-5, followed in decreasing order by NDV, parainfluenza virus 3, and Sendai virus.

Participation of lymphoid cells in the withdrawal syndrome of opiate dependent rats

Treatment of rats with 500 Rads whole-body ionizing irradiation prior to chronic administration of morphine reduced the severity of the naloxone induced withdrawal signs. In contrast, adoptive transfer of 2-6 X 10(8) lymphoid cells to irradiated rats prior to chronic morphine treatment completely restored the ability to manifest the withdrawal signs precipitated by naloxone. These observations offer the possibility that the immune system participates in opiate addiction.

Evidence of neuro-immunologic interactions: cyclosporine modifies opiate withdrawal by effects on the brain and immune components

The capacity of the immune system to participate in processes primarily considered to be central nervous system (CNS) phenomena has been suggested recently by several studies demonstrating the ability of various immune modifiers to attenuate opiate withdrawal severity. The present study demonstrates that within 2 h after injection, the immune modifier cyclosporine A (CsA) has the ability to attenuate the opiate withdrawal syndrome precipitated by naloxone in morphine-dependent animals. Furthermore, it is demonstrated that this effect of CsA can be adoptively transferred by splenic mononuclear cells from immune-modulated (CsA-treated) donors into morphine-dependent recipients. However, unlike direct injections of CsA, CsA-treated immune components require at least 24 h to achieve their full attenuating effect upon withdrawal severity. Since opiate withdrawal behavior is predominantly a CNS-mediated phenomenon, these observations suggest both direct effects of CsA on the brain as well as the participation of immune components in the opiate withdrawal syndrome. This finding lends further support to the hypothesis that immune components have the ability to modulate central nervous system activities in a neuro-immunologic axis of communication.

Opiate antinociception is altered by immunemodification: the effect of interferon, cyclosporine and radiation-induced immune suppression upon acute and long-term morphine activity

It has recently been demonstrated that various forms of immune modification result in a profound attenuation of the opiate withdrawal syndrome. Herein we investigate the extent to which some of the immune modifiers active in withdrawal attenuation affect other opiate related behaviors, namely antinociception and the development of tolerance to this effect. The observations demonstrate that immune modification by cyclosporine and irradiation exposure result in an alteration of the acute antinociceptive effect of morphine; while none of these treatments modify the development of tolerance to this property of morphine.

Modification of morphine withdrawal: effect of tuftsin, [Lys4]-tuftsinyltuftsin, tetrapeptide fragment (1-4) of substance P and its amide

Withdrawal behavior in morphine-dependent rats precipitated by naloxone was attenuated after pretreatment with the tetrapeptide tuftsin and to some extent by its synthetic derivative [Lys4]-tuftsinyltuftsin. The tetrapeptide fragment (1-4) of Substance P was ineffective in suppressing morphine-withdrawal behavior, whereas its C-amide exerted only weak action. Possible involvement of an immunological mechanism is discussed.