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

Mechanisms of brain injury after intracerebral haemorrhage

The past decade has resulted in a rapid increase in knowledge of mechanisms underlying brain injury induced by intracerebral haemorrhage (ICH). Animal studies have suggested roles for clot-derived factors and the initial physical trauma and mass effect as a result of haemorrhage. The coagulation cascade (especially thrombin), haemoglobin breakdown products, and inflammation all play a part in ICH-induced injury and could provide new therapeutic targets. Human imaging has shown that many ICH continue to expand after the initial ictus. Rebleeding soon after the initial haemorrhage is common and forms the basis of a current clinical trial using factor VIIa to prevent rebleeding. However, questions about mechanisms of injuries remain. There are conflicting data on the role of ischaemia in ICH and there is uncertainty over the role of clot removal in ICH therapy. The next decade should bring further information about the underlying mechanisms of ICH-induced brain injury and new therapeutic interventions for this severe form of stroke. This review addresses our current understanding of the mechanisms underlying ICH-induced brain injury.

Brain genomics of intracerebral hemorrhage

After intracerebral hemorrhage (ICH), many changes of gene transcription occur that may be important because they will contribute to understanding mechanisms of injury and recovery. Therefore, gene expression was assessed using Affymetrix microarrays in the striatum and the overlying cortex at 24 h after intracranial infusions of blood into the striatum of adult rats. Intracerebral hemorrhage regulated 369 of 8,740 transcripts as compared with saline-injected controls, with 104 regulated genes shared by the striatum and cortex. There were 108 upregulated and 126 downregulated genes in striatum, and 170 upregulated and 69 downregulated genes in the cortex. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) confirmed upregulation of IL-1-beta, Lipcortin 1 (annexin) and metallothionein 1,2, and downregulation of potassium voltage-gated channel, shaker-related subfamily, beta member 2 (Kcnab2). Of the functional groups of genes modulated by ICH, many metabolism and signal-transduction-related genes decreased in striatum but increased in adjacent cortex. In contrast, most enzyme, cytokine, chemokine, and immune response genes were upregulated in both striatum and in the cortex after ICH, likely in response to foreign proteins from the blood. A number of these genes may contribute to brain edema and cellular apoptosis caused by ICH. In addition, downregulation of growth factor pathways and the phosphatidylinositol 3-kinase (PI3K)/Akt pathway could also contribute to perihematoma cell death/apoptosis. Intracerebral hemorrhage-related downregulation of GABA-related genes and potassium channels might contribute to perihematoma cellular excitability and increased risk of post-ICH seizures. These genomic responses to ICH potentially provide new therapeutic targets for treatment.

Selective inhibition of nuclear factor-kappaB activation after hypoxia/ischemia in neonatal rats is not neuroprotective

Activated nuclear factor-kappaB (NFkappaB) has been shown to increase transcription of several genes that could potentially contribute to neuronal damage, such as proinflammatory cytokines, chemokines, and inducible nitric oxide synthase. The aim of our study was to investigate whether inhibition of NFkappaB activation could prevent hypoxia/ischemia (HI)-induced cerebral damage in neonatal rats. We used a cell permeable peptide (NEMO binding domain [NBD] peptide) that is known to prevent the association of the regulatory protein NEMO with IKK, the kinase that activates NFkappaB. Via this mechanism, the NBD peptide can specifically block the activation of NFkappaB, without inhibiting basal NFkappaB activity. Cerebral HI was induced in neonatal rats by occlusion of the right carotid artery followed by 90 min of hypoxia (Fio(2) = 0.08). Immediately upon reoxygenation, as well as 6 and 12 h later, rats were treated with vehicle or NBD peptide (20 mg/kg i.p.). Histologic analysis of brain damage was performed at 6 wk after HI. To assess NFkappaB activation, electromobility shift assays (EMSAs) were performed on brain nuclear extracts obtained 6 h after reoxygenation. Increased NFkappaB activity could be shown at 6 h after HI in both hemispheres. Peripheral administration of NBD peptide prevented this HI-induced increase in NFkappaB activity in both hemispheres. Histologic analysis of long-term cerebral damage revealed that inhibition of NFkappaB activation by administration of NBD peptide at 0, 6, and 12 h after HI resulted in an increment of neuronal damage. In conclusion, our data suggest that inhibition of NFkappaB activation using NBD peptide early after HI increases brain damage in neonatal rats.

Peroxisome-proliferator-activated receptor-gamma (PPARgamma) activation protects neurons from NMDA excitotoxicity

A growing body of evidence indicates that the transcription factor PPARgamma plays a beneficial role in various neurological diseases. The postulated principal mechanism underlying the beneficial effects of PPARgamma is due to its anti-inflammatory properties. However, PPARgamma exists in neurons where it may provide additional effects that regulate neuronal vulnerability. In the present study, we employed in vitro and in vivo models of excitotoxic neuronal injury to test hypothesis on the neuroprotective role of PPARgamma. The endogenous PPARgamma ligand, 15d-Delta(12,14)-Prostaglandin J2 (15d-PGJ2), and a selective thiazolidinedione PPARgamma agonist, ciglitazone, significantly reduced neuronal death in response to glutamate and NMDA-mediated, but not kainate-mediated toxicity. This neuroprotective effect of 15d-PGJ2 and ciglitazone was linked to increased PPARgamma DNA binding activity as it was fully reversed by the pretreatment of neurons with selective PPARgamma antagonists and anti-PPARgamma antibody. It was not due to the blockade of NMDA-receptor-mediated Ca++ entry. Our data demonstrate that PPARgamma activation may represent a potential target for treatment of numerous acute and chronic neurological diseases with pathologies that involve excitotoxic damage.

Contribution of extracellular proteolysis and microglia to intracerebral hemorrhage

Proteases, such as tissue plasminogen activator, thrombin, metalloproteinases, and cathepsins, have complex functions in the mammalian brain under both normal and pathological conditions. Some of these proteases are expressed by neuronal cells, whereas others are made by the immunocompetent, macrophage-like cells of the brain: the microglia. This article reviews the physiological and pathological functions of these proteinases in the brain as well as recent findings linking extracellular proteases with neuronal cell death in ischemic or hemorrhagic stroke. Better understanding of protease expression and signaling, microglial activation, and their relationship with neuronal cell death during stroke injury could contribute to the development of relevant inhibitors as novel neuroprotective agents for treating ischemic stroke and intracerebral hemorrhage.

Delayed profound local brain hypothermia markedly reduces interleukin-1beta gene expression and vasogenic edema development in a porcine model of intracerebral hemorrhage

White matter (lobar) intracerebral hemorrhage (ICH) can cause edema-related deaths and life-long morbidity. In our porcine model, ICH induces oxidative stress, acute interstitial and delayed vasogenic edema, and up-regulates interleukin-1beta (IL-1beta), a proinflammatory cytokine-linked to blood-brain barrier (BBB) opening. In brain injury models, hypothermia reduces inflammatory cytokine production and protects the BBB. Clinically, however, hypothermia for stroke treatment using surface and systemic approaches can be challenging. We tested the hypothesis that an alternative approach, i.e., local brain cooling using the ChillerPad System, would reduce IL-1beta gene expression and vasogenic edema development even if initiated several hours after ICH. We infused autologous whole blood (3.0 mL) into the frontal hemispheric white matter of 20 kg pentobarbital-anesthetized pigs. At 3 hours post-ICH, we performed a craniotomy for epidural placement of the ChillerPad. Chilled saline was then circulated through the pad for 12 hours to induce profound local hypothermia (14 degrees C brain surface temperature). We froze brains in situ at 16 hours after ICH induction, sampled perihematomal white matter, extracted RNA, and performed real-time RT-PCR. Local brain cooling markedly reduced both IL-1beta RNA levels and vasogenic edema. These robust results support the potential for local brain cooling to protect the BBB and reduce injury after ICH.

Potential markers of oxidative stress in stroke

Free radical production is increased in ischemic and hemorrhagic stroke, leading to oxidative stress that contributes to brain damage. The measurement of oxidative stress in stroke would be extremely important for a better understanding of its pathophysiology and for identifying subgroups of patients that might receive targeted therapeutic intervention. Since direct measurement of free radicals and oxidized molecules in the brain is difficult in humans, several biological substances have been investigated as potential peripheral markers. Among lipid peroxidation products, malondialdehyde, despite its relevant methodological limitations, is correlated with the size of ischemic stroke and clinical outcome, while F2-isoprostanes appear to be promising, but they have not been adequately evaluated. 8-Hydroxy-2-deoxyguanosine has been extensively investigated as markers of oxidative DNA damage but no study has been done in stroke patients. Also enzymatic and nonenzymatic antioxidants have been proposed as indirect markers. Among them ascorbic acid, alpha-tocopherol, uric acid, and superoxide dismutase are related to brain damage and clinical outcome. After a critical evaluation of the literature, we conclude that, while an ideal biomarker is not yet available, the balance between antioxidants and by-products of oxidative stress in the organism might be the best approach for the evaluation of oxidative stress in stroke patients.

Emerging medical and surgical management strategies in the evaluation and treatment of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) accounts for approximately 10% of all strokes and causes high morbidity and mortality. Rupture of the small perforating vessels of the cerebral arteries is caused by chronic hypertension, which induces pathologic changes in the small vessels and accounts for most cases of ICH; however, amyloid angiopathy and other secondary causes are being seen more frequently with the increasing age of the population. Recent computed tomographic studies have revealed that ICH is a dynamic process with up to one third of initial hemorrhages expanding within the first several hours of ictus. Secondary injury is believed to result from the development of cerebral edema and the release of specific neurotoxins associated with the breakdown products of hemoglobin. Treatment is primarily supportive. Surgical evacuation is the treatment of choice for patients with neurologic deterioration from infratentorial hematomas. Randomized trials comparing surgical evacuation to medical management have shown no benefit of surgical removal of supratentorial hemorrhages. New strategies focusing on early hemostasis, improved critical care management, and less invasive surgical techniques for clot evacuation are promising to decrease secondary neurologic injury. We review the pathophysiology of ICH, its medical management, and new treatment strategies for improving patient outcome.

Mmp-9 deficiency enhances collagenase-induced intracerebral hemorrhage and brain injury in mutant mice

Matrix metalloproteinase-9 (MMP-9) participates in the disregulation of blood-brain barrier during hemorrhagic transformation, and exacerbates brain injury after cerebral ischemia. However, the consequences of long-term inhibition or deficiency of MMP-9 activity (which might affect normal collagen or matrix homeostasis) remains to be determined. The authors investigated how MMP-9 gene deficiency enhances hemorrhage and increases mortality and neurologic deficits in a collagenase-induced intracerebral hemorrhage (ICH) model in MMP-9-knockout mice. MMP-9-knockout and corresponding wild-type mice at 20 to 35 weeks were used to model an aged population (because advanced age is a significant risk factor in human ICH). Collagenase VII-S (0.5 microL, 0.075 U) was injected into the right basal ganglia in mice and mortality, neurologic deficits, brain edema, and hemorrhage size measured. In addition, MMP-9 activity, brain collagen content, blood coagulation, cerebral arterial structure, and expressions of several MMPs were examined. Increased hemorrhage and brain edema that correlated with higher mortality and neurologic deficits were found in MMP-9-knockout mice. No apparent structural changes were observed in cerebral arteries, even though brain collagen content was reduced in MMP-9-knockout mice. MMP-9-knockout mice did exhibit an enhanced expression of MMP-2 and MMP-3 in response to ICH. The results indicate that a deficiency of MMP-9 gene in mutant mice increases collagenase-induced hemorrhage and the resulting brain injury. The intriguing relationship between MMP-9 deficiency and collagenase-induced ICH may reflect the reduction in collagen content and an enhanced expression of MMP-2 and MMP-3.

Protective role of tuftsin fragment 1-3 in an animal model of intracerebral hemorrhage

Intracerebral hemorrhage (ICH) causes morbidity and mortality and commonly follows the reperfusion after an ischemic event. Tissue plasminogen activator (tPA), a fibrinolytic serine protease, is routinely given for the treatment of stroke. However, tPA also can promote neuronal death, suggesting that caution should be exercised when using it. Furthermore, tPA upon brain injury mediates microglial activation and modulates neuronal survival. To investigate the role of tPA and microglia during brain hemorrhage, we induced experimentally ICH by intracerebral injection of collagenase. Seven days after the introduction of ICH, it persisted in tPA-deficient (tPA(-/-)) mice but is drastically reduced in size in wild-type mice. Three weeks after ICH, there are still red blood cells in tPA(-/-) but not in wild-type animals. Activated microglia persist around the injury site. When microglial activation is inhibited by tuftsin fragment 1-3 macrophage/microglial inhibitory factor (MIF), the stroke injury volume is significantly reduced, and the neurobehavioral deficits exhibited by the mice are improved. Our results suggest that endogenous tPA assists in the clearance of intracerebral hemorrhage, presumably by affecting microglial activation, and MIF could be a valuable neuroprotective agent for the treatment of ICH.

Spontaneous intracerebral hemorrhage: a review

Spontaneous intracerebral hemorrhage (SICH) is a blood clot that arises in the brain parenchyma in the absence of trauma or surgery. This entity accounts for 10 to 15% of all strokes and is associated with a higher mortality rate than either ischemic stroke or subarachnoid hemorrhage. Common causes include hypertension, amyloid angiopathy, coagulopathy, vascular anomalies, tumors, and various drugs. Hypertension, however, remains the single greatest modifiable risk factor for SICH. Computerized tomography scanning is the initial diagnostic modality of choice in SICH, and angiography should be considered in all cases except those involving older patients with preexisting hypertension in thalamic, putaminal, or cerebellar hemorrhage. Medical management includes venous thrombosis prophylaxis, gastric cytoprotection, and aggressive rehabilitation. Anticonvulsant agents should be prescribed in supratentorial SICH, whereas the management of hypertension is controversial.

To date, nine prospective randomized controlled studies have been conducted to compare surgical and medical management of SICH. Although definitive evidence favoring surgical intervention is lacking, there is good theoretical rationale for early surgical intervention. Surgery should be considered in patients with moderate to large lobar or basal ganglia hemorrhages and those suffering progressive neurological deterioration. Elderly patients in whom the Glasgow Coma Scale score is less than 5, those with brainstem hemorrhages, and those with small hemorrhages do not typically benefit from surgery. Patients with cerebellar hemorrhages larger than 3 cm, those with brainstem compression and hydrocephalus, or those exhibiting neurological deterioration should undergo surgical evacuation of the clot. It is hoped that the forthcoming results of the International Surgical Trial in IntraCerebral Hemorrhage will help formulate evidence-based recommendations regarding the role of surgery in SICH.

Cerebral vasospasm after subarachnoid hemorrhage: putative role of inflammation

Cerebral vasospasm is a common, formidable, and potentially devastating complication in patients who have sustained subarachnoid hemorrhage (SAH). Despite intensive research efforts, cerebral vasospasm remains incompletely understood from both the pathogenic and therapeutic perspectives. At present, no consistently efficacious and ubiquitously applied preventive and therapeutic measures are available in clinical practice. Recently, convincing data have implicated a role of inflammation in the development and maintenance of cerebral vasospasm. A burgeoning (although incomplete) body of evidence suggests that various constituents of the inflammatory response, including adhesion molecules, cytokines, leukocytes, immunoglobulins, and complement, may be critical in the pathogenesis of cerebral vasospasm. Recent studies attempting to dissect the cellular and molecular basis of the inflammatory response accompanying SAH and cerebral vasospasm have provided a promising groundwork for future studies. It is plausible that the inflammatory response may indeed represent a critical common pathway in the pathogenesis of cerebral vasospasm pursuant to SAH. Investigations into the nature of the inflammatory response accompanying SAH are needed to elucidate the precise role(s) of inflammatory events in SAH-induced pathologies.

Tauroursodeoxycholic acid reduces apoptosis and protects against neurological injury after acute hemorrhagic stroke in rats

Tauroursodeoxycholic acid (TUDCA), an endogenous bile acid, modulates cell death by interrupting classic pathways of apoptosis. Intracerebral hemorrhage (ICH) is a devastating acute neurological disorder, without effective treatment, in which a significant loss of neuronal cells is thought to occur by apoptosis. In this study, we evaluated whether TUDCA can reduce brain injury and improve neurological function after ICH in rats. Administration of TUDCA before or up to 6 h after stereotaxic collagenase injection into the striatum reduced lesion volumes at 2 days by as much as 50%. Apoptosis was approximately 50% decreased in the area immediately surrounding the hematoma and was associated with a similar inhibition of caspase activity. These changes were also associated with improved neurobehavioral deficits as assessed by rotational asymmetry, limb placement, and stepping ability. Furthermore, TUDCA treatment modulated expression of certain Bcl-2 family members, as well as NF-kappaB activity. In addition to its protective action at the mitochondrial membrane, TUDCA also activated the Akt-1protein kinase Balpha survival pathway and induced Bad phosphorylation at Ser-136. In conclusion, reduction of brain injury underlies the wide-range neuroprotective effects of TUDCA after ICH. Thus, given its clinical safety, TUDCA may provide a potentially useful treatment in patients with hemorrhagic stroke and perhaps other acute brain injuries associated with cell death by apoptosis.

Effect of trans-resveratrol on signal transduction pathways involved in paclitaxel-induced apoptosis in human neuroblastoma SH-SY5Y cells

trans-Resveratrol (3,4',5-trihydroxystilbene) is able to significantly reduce paclitaxel-induced apoptosis in the human neuroblastoma (HN) SH-SY5Y cell line, acting on several cellular signaling pathways that are involved in paclitaxel-induced apoptosis. trans-Resveratrol reverses phosphorylation of Bcl-2 induced by paclitaxel and concomitantly blocks Raf-1 phosphorylation, also observed after paclitaxel exposure, thus suggesting that Bcl-2 inactivation may be dependent on the activation of the Raf/Ras cascade. trans-Resveratrol also reverses the sustained phosphorylation of JNK/SAPK, which specifically occurs after paclitaxel exposure.Overall, our observations demonstrate that (a) the toxic action of paclitaxel on neuronal-like cells is not only related to the effect of the drug on tubulin, but also to its capacity to activate several intracellular pathways leading to inactivation of Bcl-2, thus causing cells to die by apoptosis, (b) trans-resveratrol significantly reduces paclitaxel-induced apoptosis by modulating the cellular signaling pathways which commit the cell to apoptosis.

Delayed treatment with MLN519 reduces infarction and associated neurologic deficit caused by focal ischemic brain injury in rats via antiinflammatory mechanisms involving nuclear factor-kappaB activation, gliosis, and leukocyte infiltration

Secondary brain injury due to ischemia includes the infiltration of leukocytes into the brain parenchyma mediated by activation of nuclear factor-kappaB (NF-kappaB), which is activated by proteasome degradation. Neuroprotection with the proteasome inhibitor MLN519 has previously been reported to decrease ischemic brain injury in rats. The authors used higher doses of MLN519 to evaluate the neuroprotection therapeutic window after 24 hours of brain injury in rats as correlated to proteasome levels, activated NF-kappaB immunoreactivity, and leukocyte infiltration. Male Sprague-Dawley rats were subjected to 2-hour middle cerebral artery occlusion (MCAO) and recovery. MLN519 or vehicle was administered after injury with a single injection given in delayed increments of 2 hours (i.e., 4, 6, or 8 hours after MCAO). Treatment with MLN519 up to 6 hours after MCAO (4 hours after reperfusion) effectively reduced neuronal and astrocytic degeneration, decreased cortical infarct volume, and increased neurologic recovery. These effects were related to >80% reductions in blood proteasome levels, reduced neutrophil infiltration, and a decrease in activated NF-kappaB immunoreactivity. This improved neuroprotection profile and antiinflammatory effect of MLN519 provides an exciting avenue for potential treatment of focal ischemic brain injury in humans.

Fibrinolysis therapy achieved with tissue plasminogen activator and aspiration of the liquefied clot after experimental intracerebral hemorrhage: rapid reduction in hematoma volume but intensification of delayed edema formation

OBJECT

Fibrinolysis therapy accomplished using tissue plasminogen activator (tPA) and aspiration is considered to be a viable alternative to microsurgery and medical therapy for the treatment of deep-seated spontaneous intracerebral hematomas (SICHs). Tissue plasminogen activator is a mediator of thrombin- and ischemia-related delayed edema. Because both thrombin release and ischemia occur after SICH, the authors planned to investigate the effect of fibrinolytic therapy on hematoma and delayed edema volume.

METHODS

A spherical hematoma was created in the frontal white matter of 18 pigs. In the tPA-treated group (nine pigs), a mean of 1.55 ml tPA was injected into the clot and the resulting liquefied blood was aspirated. Magnetic resonance (MR) imaging was performed on Days 0 (after surgery), 4, and 10, and the volumes of hematoma and edema were determined. In the animals not treated with tPA (untreated group; nine pigs), the volume of hematoma dropped from 1.43+/-0.42 ml on Day 0 to 0.85+/-0.28 ml on Day 10. In the tPA-treated group, the volume of hematoma was reduced from 1.51 +/- 0.28 ml on Day 0 to 0.52 +/- 0.39 ml on Day 10. In comparison with the untreated group, the reduction in hematoma volume was significantly accelerated (p = 0.02). In the untreated group, perihematomal edema increased from 0.32 +/- 0.61 ml to 1.73 +/- 0.73 ml on Day 4, before dropping to 1.17 +/- 0.92 ml on Day 10. In the tPA-treated group, the volume of the edema increased from 0.09 +/- 0.21 ml on Day 0 to 1.93 +/- 0.79 ml on Day 4, and further to 3.34 +/- 3.21 ml on Day 10. The increase in edema volume was significantly more pronounced in the tPA-treated group (p = 0.04).

CONCLUSIONS

Despite a significantly accelerated reduction in hematoma volume, the development of delayed perifocal edema was intensified by fibrinolytic therapy, which is probably related to the function of tPA as a mediator of edema formation after thrombin release and ischemia. Further experimental and clinical investigations are required to establish the future role of fibrinolysis in the management of SICH.

Quantitative real-time RT-PCR analysis of inflammatory gene expression associated with ischemia-reperfusion brain injury

Ischemia-reperfusion brain injury initiates an inflammatory response involving the expression of adhesion molecules and cytokines, some of which are regulated by the nuclear transcription factor NF-kappaB. In this study the authors examined mRNA expression levels for several important genes associated with inflammation at five time points (3, 6, 12, 24, and 72 hours) after transient middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats. A sensitive and quantitative technique (TaqMan real-time QRT-PCR) was used to simultaneously measure mRNA levels for key cell adhesion molecules and inflammatory cytokines. Gene expression increased significantly in the injured hemisphere for interleukin (IL)-1beta (12-fold increase at 24 hours), IL-6 (25-fold increase at 6 hours) and ICAM-1 (4-fold increase at 24 hours), and the interhemispheric differences for these genes were significant for every time point examined (P < 0.05 for all values). Tumor necrosis factor-alpha mRNA was upregulated in the injured versus uninjured hemisphere from 3 to 24 hours (5-fold increase at 6 hours), while E-selectin showed a significant increase in mRNA levels from 6 to 24 hours after MCAO (10-fold increase at 6 hours) (P < 0.05 for all values). VCAM-1 mRNA levels did not respond differentially to injury at any time point between the two brain hemispheres. At all time points examined, activated NF-kappaB immunoreactivity was observed in cells throughout the infarct-damaged tissue. These results are consistent with the proinflammatory properties of the induced molecules, which are involved in the initiation of the inflammatory cascade, and may thus contribute to secondary cellular responses that lead to further brain damage.

Early clinical experience with the novel proteasome inhibitor PS-519

AIMS

The main objective of this study was to investigate the safety, tolerability and pharmacodynamics of the novel proteasome inhibitor PS-519 in young male volunteers. Many pro-inflammatory mediators such as cytokines and cell adhesion molecules that are responsible for the development of the cerebral infarct are under the control of the transcription factor Nuclear Factor kappa-B (NF-kappaB). The activity of NF-kappaB is itself tightly regulated through the multicatalytic enzyme known as the proteasome. PS-519 is a novel and highly selective small molecule that inhibits the proteasome. An ex vivo assay of 20S proteasome activity allows monitoring of the drug effect in blood. PS-519 is protective in multiple animal models of cerebral ischaemia over a range of doses that achieve 20S inhibition of 40%-80%.

METHODS

PS-519 has been administered to healthy male volunteers as single and repeated doses up to 1.6 mg m(-2). It was given as an intravenous bolus over 20-30 s in a double blind, randomized, placebo-controlled phase I study, examining vital signs, safety, tolerability and blood 20S proteasome inhibition.

RESULTS

Thirty-nine subjects received single doses of 0.012 mg m-2-1.6 mg m(-2) and 28 subjects received doses of 0.5 mg m(-2)-1.6 mg m(-2) on three consecutive days. The drug was well tolerated. There was no clear treatment-emergent symptom or abnormality of laboratory tests. Proteasome inhibition in blood samples as measured by 20S assay achieved the intended maximum target level of 70-80% with 1.6 mg m(-2), and was reproducible with repeated dosing.

CONCLUSIONS

This study has demonstrated that proteasome inhibition is well tolerated by healthy subjects at levels that are maximally neuroprotective in experimental conditions. Further clinical evaluation appears justified.

Experimental animal models of intracerebral hemorrhage

Experimental animal ICH models are able to reproduce the overall important pathophysiologic events documented in human ICH, including edema development, markedly reduced metabolism, and tissue pathologic responses. Thus, ICH models serve as an important tool for new understanding of the mechanisms underlying brain injury after an intracerebral bleed. Currently, ongoing studies in several laboratories using these models investigating secondary inflammatory responses as well as intracellular signaling and molecular events are expected to provide therapeutic targets for treating ICH. Future studies should also be directed at one aspect of ICH modeling that has received little attention--potential differences in the hemostatic systems and physical and biochemical properties of clots in animals that might make their susceptibility to aspiration and/or fibrinolytic drugs and rates of rehemorrhage different than in human beings. Also, future efforts should be directed toward the development of a model that mimics the pathophysiologic processes that lead to spontaneous ICH, progression of hemorrhage, and the recurrence of bleeding in human beings. This model would not only provide better understanding of the dynamic events leading to ICH and tissue injury but should also lead to the development of highly effective pharmacologic and surgical treatments.

Cell death in experimental intracerebral hemorrhage: the "black hole" model of hemorrhagic damage

Intracerebral hemorrhage (ICH) has a poor prognosis that may be the consequence of the hematoma's effect on adjacent and remote brain regions. Little is known about the mechanism, location, and severity of such effects. In this study, rats subjected to intracerebral blood injection were examined at 100 days. Stereology (neuronal count and density) and volume measures in the perihematoma rim, the adjacent and overlying brain, and the substantia nigra pars reticulata (SNr) were compared with contralateral brain regions at 100 days and the perihemorrhage region at 24 hours and 7 days. In addition, cytochrome c release was investigated at 24 hours, 3 days, and 7 days. At 100 days, post-ICH rats showed no difference in neuronal density in the perihemorrhagic scar region or regions of the striatum immediately surrounding and distal to the perihemorrhage scar. The cell density index in the ipsilateral field was 16.2 +/- 3.8 versus the contralateral control field of 15.6 +/- 3.2 (not significant). Volume measurements of the ipsilateral striatum revealed a 20% decrease that was compensated by an increase in ipsilateral ventricular size. The area of the initial ICH as measured by magnetic resonance imaging correlated with the degree of atrophy. In the region immediately surrounding the hematoma, cytochrome c immunoreactivity increased at 24 hours and 3 days, and returned toward baseline by day 7. At 24 hours, stereology in the peri-ICH region showed decreased density in the region where cytochrome c immunoreactivity was the highest. Neuronal density of the ipsilateral SNr was significantly less than the contralateral side (9.6 +/- 1.9 vs 11.6 +/- 2.3). Histologic damage from ICH occurred mainly in the immediate perihemorrhage region. Except for SNr, we found no evidence of neuronal loss in distal regions. We have termed this continued destruction of neurons, which occurs over at least 3 days as the neurons come into proximity to the hematoma, the "black hole" model of hemorrhagic damage.

Neuronal, but not microglial, accumulation of extravasated serum proteins after intracerebral hemolysate exposure is accompanied by cytochrome c release and DNA fragmentation

Vasogenic edema after oxidative injury has been accompanied by intracellular accumulation of serum proteins and nuclear damage. This study sought to determine whether serum protein accumulation, along with other markers of brain injury, was present after exposure to intracerebral hemolysate, an oxidant model of intracerebral hemorrhage (ICH). Saline (n = 24) or hemolysate (n = 30) was injected into the caudate-putamen of adult Sprague-Dawley rats. Compared with saline, hemolysate deposition was associated with intracellular accumulation of serum proteins as evidenced by Evans blue uptake in neurons and microglia at 4 and 24 hours. Intracellular Evans blue colocalized with DNA fragmentation detected by nick end-labeling and whose presence was confirmed by gel electrophoresis. Immunoblots of cytosolic fractions confirmed cytochrome c release. Immunostaining established colocalization of cytosolic cytochrome c and intracellular Evans blue at 4 hours. At 24 hours, cytosolic cytochrome c was evident in astrocytes surrounding Evans blue-positive cells. Immunoblot analysis and immunostaining revealed HSP70 induction at 24 hours in regions adjacent to intracellular serum accumulation. Neuronal accumulation of extravasated serum proteins in this model of ICH was associated with cytochrome c release, DNA fragmentation, and cell death. Stress protein induction in adjacent regions suggested that vasogenic edema might have exacerbated cellular dysfunction and cell death after ICH.

Anti-apoptotic effect of trans-resveratrol on paclitaxel-induced apoptosis in the human neuroblastoma SH-SY5Y cell line

Paclitaxel, an anticancer drug, induces apoptosis in human neuroblastoma cell line SH-SY5Y. The addition of trans-resveratrol, a natural antioxidant present in grapes and red wine, to SH-SY5Y cultures exposed to paclitaxel significantly reduces cellular death. The neuroprotective action of trans-resveratrol is due neither to its antioxidant capacity nor to interference with the polymerization of tubulin induced by paclitaxel. However, trans-resveratrol is able to inhibit the activation of caspase 7 and degradation of poly-(ADP-ribose)-polymerase which occur in SH-SY5Y exposed to paclitaxel. Resveratrol, therefore, exerts its anti-apoptotic effect by modulating the signal pathways that commit these neuronal-like cells to apoptosis.