Statin Pre-Treatment Protects Brain Against Focal Cerebral Ischemia in Diabetic Mice

BACKGROUND

Cerebrovascular diseases and other vascular complications are common and cause considerable mortality and morbidity in diabetes mellitus. Recent studies suggest that statins reduce the incidence of stroke in diabetic as well as non-diabetic patients. The outcome of stroke is shown to be worse in diabetics. However, the effect of statins on the outcome of stroke occurring in diabetics is not clear. The purpose of this study was to investigate the effect of pre-treatment with statins on focal cerebral ischemia in diabetic mice.

MATERIALS AND METHODS

Swiss albino mice were randomized into two groups. Diabetes was induced in the first group by intravenous streptozotosin injection. The second group served as non-diabetic. After 4 weeks, half of the mice in diabetic and non-diabetic groups were randomized to receive intraperitoneal simvastatin 1 mg/kg/day or saline treatment for 14 days. Subsequently, mice were subjected to 90 min of proximal middle cerebral artery occlusion and 24 h of reperfusion. Sham-operation was also performed for each group. After 24 h of reperfusion, neurological deficits were scored and the infarct volume was measured on Nissl stained brain sections.

RESULTS

Infarct volume (median, interquartile range) was significantly increased in the diabetic group (60.7 mm(3)) compared to non-diabetic group (53.4 mm(3)). Statin pre-treatment significantly reduced the infarct volume (to 40.4; 33.5 mm(3), respectively) and neurological disability scores both in diabetic and non-diabetic groups.

CONCLUSIONS

These data suggest that diabetes aggravates the ischemic damage after focal cerebral ischemia and statin pre-treatment protects the brain in diabetic as well as healthy animals. Statin treatment may favorably affect stroke outcome in diabetic patients in addition to decreasing stroke incidence.

Treatment of malignant gliomas with mitoxantrone-loaded poly (lactide-co-glycolide) microspheres

OBJECTIVE

Mitoxantrone (MTZ) has potent in vitro activity against malignant glioma cell lines, but it cannot be used effectively as a systemic agent for the treatment of brain tumors because of its poor central nervous system penetration. However, MTZ-loaded poly(lactide-co-glycolide) (PLGA) microspheres may be injected into the peritumoral area and into tumor tissue to provide effective and sustained local drug concentrations without causing systemic side effects.

METHODS

Fisher rats were randomized into three groups. The first group (n = 9) was concomitantly implanted with rat glioma (RG2) cells and blank PLGA microspheres. The second group (n = 6) was implanted with RG2 cells and MTZ-loaded PLGA microspheres. The third group (n = 9) was implanted with RG2 cells, and MTZ-loaded PLGA microspheres were injected into the same area after 7 days. Animals were sacrificed on Day 15 or 35. Tumor volumes were measured after hematoxylin and eosin staining. Distribution kinetics of MTZ in the brain was determined by high-performance liquid chromatography in nine rats injected with MTZ-loaded microspheres.

RESULTS

The tumor volumes were 76 +/- 11 and 107 +/- 11 mm (mean +/- standard error) on Days 15 (n = 6) and 35 (n = 3), respectively, in the control group. In rats treated with MTZ-loaded microspheres on Day 7, tumor volumes were significantly reduced to 17 +/- 4 and 23 +/- 2 mm on Days 15 (n = 6) and 35 (n = 3), respectively. No tumor formation was observed when glioma cells and MTZ-loaded PLGA microspheres were implanted concomitantly (n = 6). No systemic side effects or parenchymal inflammatory infiltration were observed in either group of rats. Brain MTZ concentration was highest at the injection site and declined with time and distance from the injection site and with time.

CONCLUSION

These data demonstrate that MTZ-loaded PLGA microspheres can deliver therapeutic concentrations of drug to the tumor and prevent glioma growth without causing side effects. This treatment method may increase the efficiency of antineoplastic therapy and positively impact survival.

Preparation and characterization of PLGA nanospheres for the targeted delivery of NR2B-specific antisense oligonucleotides to the NMDA receptors in the brain

Treatment of central nervous system (CNS) diseases with potentially useful pharmaceuticals is prevented by the blood-brain barrier (BBB). The BBB is a unique protective barrier in the body. It is formed by epithelial-like tight junctions, which are expressed by the brain capillary endothelial cells. Although most molecules are potentially active in the CNS, they cannot readily enter the brain because of their properties. Antisense oligonucleotides (ODNs) have a great potential as neuropharmaceuticals; however, the large size and polar nature of nucleic acid drugs prevent these molecules from bypassing the BBB and readily entering the CNS following systemic administration. One approach to improve both the pharmacokinetics and the pharmacodynamics of ODNs involves the use of sustained-release polymer formulations, such as poly(lactide-co-glycolide) (PLGA) nanoparticulate systems. In this study, nanospheres were prepared by the emulsification diffusion technique and characterized in terms of particle size, surface morphology, encapsulation efficiency, in vitro release profiles and ODN stability. The nanospheres produced were spherical with homogenous size distribution. Nanospheres were prepared with different encapsulation efficiency. Release profiles of formulations were also evaluated. The results show that formulations with different ODN content exhibited different release profiles. Moreover, the chemical integrity of ODN during the processes was conserved. These results demonstrate that a stable ODN formulation could be prepared utilizing PLGA nanospheres as a potential delivery system for the treatment of CNS diseases.

From spreading depression to the trigeminovascular system

Migraine headaches have a complex pathophysiology; both vascular and neuronal mechanisms have been proposed. One possible scenario begins with brain-initiated events evolving to cortical spreading depression (CSD), which in turn activates the trigeminal nerve to cause headaches. Experimental evidence supports a relationship between CSD as a cause of migraine aura as well as CSD as a cause of trigeminal activation. Susceptibility to CSD and to migraine appears to be genetically determined. In some migraine subtypes, genes controlling translocation of calcium, sodium and potassium have been implicated, perhaps altering the susceptibility to CSD. This chapter briefly reviews current knowledge pertaining to migraine pathophysiology with emphasis on current notions linking disturbances in ion flux to the genesis of headache.

Suppression of cortical spreading depression in migraine prophylaxis

OBJECTIVE

Topiramate, valproate, propranolol, amitriptyline, and methysergide have been widely prescribed for migraine prophylaxis, but their mechanism or site of action is uncertain. Cortical spreading depression (CSD) has been implicated in migraine and as a headache trigger and can be evoked in experimental animals by electrical or chemical stimulation. We hypothesized that migraine prophylactic agents suppress CSD as a common mechanism of action.

METHODS

Rats were treated either acutely or chronically over weeks and months, with one of the above migraine prophylactic drugs, vehicle, or D-propranolol, a clinically ineffective drug. The impact of treatment was determined on the frequency of evoked CSDs after topical potassium application or on the incremental cathodal stimulation threshold to evoke CSD.

RESULTS

Chronic daily administration of migraine prophylactic drugs dose-dependently suppressed CSD frequency by 40 to 80% and increased the cathodal stimulation threshold, whereas acute treatment was ineffective. Longer treatment durations produced stronger CSD suppression. Chronic D-propranolol treatment did not differ from saline control.

INTERPRETATION

Our data suggest that CSD provides a common therapeutic target for widely prescribed migraine prophylactic drugs. Assessing CSD threshold may prove useful for developing new prophylactic drugs and improving upon existing ones.

Advances in stroke neuroprotection: hyperoxia and beyond

Refinements in patient selection, improved methods of drug delivery, use of more clinically relevant animal stroke models, and the use of combination therapies that target the entire neurovascular unit make stroke neuroprotection an achievable goal. This article provides an overview of the major mechanisms of neuronal injury and the status of neuroprotective drug trials and reviews emerging strategies for treatment of acute ischemic stroke. Advances in the fields of stem cell transplantation, stroke recovery, molecular neuroimaging, genomics, and proteomics will provide new therapeutic avenues in the near future. These and other developments over the past decade raise expectations that successful stroke neuroprotection is imminent.

Serial analysis of gene expression in the hippocampus of patients with mesial temporal lobe epilepsy

Hippocampal sclerosis constitutes the most frequent neuropathological finding in patients with medically intractable mesial temporal lobe epilepsy. Serial analysis of gene expression was used to get a global view of the gene profile in human hippocampus in control condition and in epileptic condition associated with hippocampal sclerosis. Libraries were generated from control hippocampus, obtained by rapid autopsy, and from hippocampal surgical specimens of patients with mesial temporal lobe epilepsy and the classical pattern of hippocampal sclerosis. More than 50,000 tags were analyzed (28,282, control hippocampus; 25,953, hippocampal sclerosis) resulting in 9206 (control hippocampus) and 9599 (hippocampal sclerosis) unique tags (genes), each representing a specific mRNA transcript. Comparison of the two libraries resulted in the identification of 143 transcripts that were differentially expressed. These genes belong to a variety of functional classes, including basic metabolism, transcription regulation, protein synthesis and degradation, signal transduction, structural proteins, regeneration and synaptic plasticity and genes of unknown identity of function. The database generated by this study provides an extensive inventory of genes expressed in human control hippocampus, identifies new high-abundant genes associated with altered hippocampal morphology in patients with mesial temporal lobe epilepsy and serves as a reference for future studies aimed at detecting hippocampal transcriptional responses under various pathological conditions.

Development and Brain Delivery of Chitosan−PEG Nanoparticles Functionalized with the Monoclonal Antibody OX26

The inhibition of the caspase-3 enzyme is reported to increase neuronal cell survival following cerebral ischemia. The peptide Z-DEVD-FMK is a specific caspase inhibitor, which significantly reduces vulnerability to the neuronal cell death. However, this molecule is unable to cross the blood-brain barrier (BBB) and to diffuse into the brain tissue. Thus, the development of an effective delivery system is needed to provide sufficient drug concentration into the brain to prevent cell death. Using the avidin (SA)-biotin (BIO) technology, we describe here the design of chitosan (CS) nanospheres conjugated with poly(ethylene glycol) (PEG) bearing the OX26 monoclonal antibody whose affinity for the transferrin receptor (TfR) may trigger receptor-mediated transport across the BBB. These functionalized CS-PEG-BIO-SA/OX26 nanoparticles (NPs) were characterized for their particle size, zeta potential, drug loading capacity, and release properties. Fluorescently labeled CS-PEG-BIO-SA/OX26 nanoparticles were administered systemically to mice in order to evaluate their efficacy for brain translocation. The results showed that an important amount of nanoparticles were located in the brain, outside of the intravascular compartment. These findings, which were also confirmed by electron microscopic examination of the brain tissue indicate that this novel targeted nanoparticulate drug delivery system was able to translocate into the brain tissue after iv administration. Consequently, these novel nanoparticles are promising carriers for the transport of the anticaspase peptide Z-DEVD-FMK into the brain.

VEGF protects brain against focal ischemia without increasing blood--brain permeability when administered intracerebroventricularly

Delayed administration of vascular endothelial growth factor (VEGF) promotes functional recovery after focal cerebral ischemia. However, early intravenous injection of VEGF increases blood-brain barrier (BBB) leakage, hemorrhagic transformation and infarct volume whereas its application to cortical surface is neuroprotective. We have investigated whether or not early intracerebroventricular administration of VEGF could replicate the neuroprotective effect observed with topical application and the mechanism of action of this protection. Mice were subjected to 90 mins middle cerebral artery (MCA) occlusion and 24 h of reperfusion. Vascular endothelial growth factor (8 ng, intracerebroventricular) was administered 1 or 3 h after reperfusion. Compared with the vehicle-treated (intracerebroventricular) group, VEGF decreased the infarct volume along with BBB leakage in both treatment groups. Neurologic disability scores improved in parallel to the changes in infarct volume. Independently of the decrease in infarct size, VEGF also reduced the number of TUNEL-positive apoptotic neurons. Phospo-Akt levels were significantly higher in ischemic hemispheres of the VEGF-treated mice. Contrary to intracerebroventricular route, intravenous administration of VEGF (15 microg/kg) enhanced the infarct volume as previously reported for the rat. In conclusion, single intracerebroventricular injection of VEGF protects brain against ischemia without adversely affecting BBB permeability, and has a relatively long therapeutic time window. This early neuroprotective action, observed well before recovery-promoting actions such as angiogenesis, possibly involves activation of the PI-3-Akt pathway.

Mitochondrial complex I and IV activities in leukocytes from patients with parkin mutations

The parkin protein functions as a RING-type ubiquitin protein ligase. Considering the possibility that impaired ubiquitin-proteosomal system activity may impair antioxidant defenses and enhance oxidative stress, we have investigated the activity of mitochondrial respiratory enzymes in patients with parkin gene mutations. A significant decrease in the leukocyte complex I activity was found both in patients with parkin mutations (62.5%) and idiopathic PD (64.5%) compared with age-matched controls (P < 0.001). Complex IV activity was also decreased significantly in idiopathic PD patients (60%), but no difference was detected between controls and patients with parkin mutations.

Apoptotic and Necrotic Death Mechanisms Are Concomitantly Activated in the Same Cell After Cerebral Ischemia

BACKGROUND AND PURPOSE

Both necrotic and apoptotic cell death mechanisms are activated after cerebral ischemia. However, whether they are concomitantly active in the same cell or in discrete cell populations is not known.

METHODS

We investigated activation of both pathways at the cellular level in mice brains subjected to transient or permanent focal ischemia.

RESULTS

Four hours after ischemia, diffuse cathepsin-B spillage into cytoplasm, suggesting lysosomal leakage, was observed within neurons immunoreactive for the active form of caspase-3 (p20). Ischemic neurons with a leaky plasma membrane (positive for propidium iodide) were colabeled with caspase-cleaved actin fragment and exhibited TUNEL-positive nuclei having apoptotic morphology. At 72 hours, up to 27% of cells with caspase activity displayed morphological features suggestive of secondary necrosis.

CONCLUSIONS

These data, demonstrating an early and concurrent increase in caspase-3 and cathepsin-B activities followed by appearance of caspase-cleavage products, DNA fragmentation, and membrane disintegration, suggest that subroutines of necrotic and apoptotic cell death are concomitantly activated in ischemic neurons and that the dominant cell death phenotype is determined by the relative speed of each process.

Validity and Reliability of the Turkish Migraine Disability Assessment (MIDAS) Questionnaire

OBJECTIVES

The aim of this study is to assess the comprehensibility, internal consistency, patient-physician reliability, test-retest reliability, and validity of Turkish version of Migraine Disability Assessment (MIDAS) questionnaire in patients with headache.

BACKGROUND

MIDAS questionnaire has been developed by Stewart et al and shown to be reliable and valid to determine the degree of disability caused by migraine.

DESIGN AND METHODS

This study was designed as a national multicenter study to demonstrate the reliability and validity of Turkish version of MIDAS questionnaire. Patients applying to 17 Neurology Clinics in Turkey were evaluated at the baseline (visit 1), week 4 (visit 2), and week 12 (visit 3) visits in terms of disease severity and comprehensibility, internal consistency, test-retest reliability, and validity of MIDAS. Since the severity of the disease has been found to change significantly at visit 2 compared to visit 1, test-retest reliability was assessed using the MIDAS scores of a subgroup of patients whose disease severity remained unchanged (up to +/-3 days difference in the number of days with headache between visits 1 and 2).

RESULTS

A total of 306 patients (86.2% female, mean age: 35.0 +/- 9.8 years) were enrolled into the study. A total of 65.7%, 77.5%, 82.0% of patients reported that "they had fully understood the MIDAS questionnaire" in visits 1, 2, and 3, respectively. A highly positive correlation was found between physician and patient and the applied total MIDAS scores in all three visits (Spearman correlation coefficients were R= 0.87, 0.83, and 0.90, respectively, P <.001). Internal consistency of MIDAS was assessed using Cronbach's alpha and was found at acceptable (>0.7) or excellent (>0.8) levels in both patient and physician applied MIDAS scores, respectively. Total MIDAS score showed good test-retest reliability (R= 0.68). Both the number of days with headache and the total MIDAS scores were positively correlated at all visits with correlation coefficients between 0.47 and 0.63. There was also a moderate degree of correlation (R= 0.54) between the total MIDAS score at week 12 and the number of days with headache at visit 2 + visit 3, which quantify headache-related disability over a 3-month period similar to MIDAS questionnaire.

CONCLUSION

These findings demonstrated that the Turkish translation is equivalent to the English version of MIDAS in terms of internal consistency, test-retest reliability, and validity. Physicians can reliably use the Turkish translation of the MIDAS questionnaire in defining the severity of illness and its treatment strategy when applied as a self-administered report by migraine patients themselves.

Loss of NeuN immunoreactivity after cerebral ischemia does not indicate neuronal cell loss: a cautionary note

NeuN immunoreactivity is used as a specific marker for neurons. The number of NeuN-positive cells decreases under pathological conditions. This finding is usually considered as an evidence of neuronal loss. However, decrease in NeuN labeling may also be caused by depletion of the protein or loss of its antigenicity. Hence, we have investigated the morphological features of neurons that lost NeuN immunoreactivity and the NeuN protein levels in mouse brain after cerebral ischemia. The number of NeuN-labeled cells was decreased 6 h after a mild ischemic insult (30 min middle cerebral artery occlusion) in penumbral and core regions. Hematoxylin and eosin (H&E) staining of adjacent sections showed that neurons in the penumbra were not disintegrated but displayed early ischemic changes. The nuclear NeuN staining was dramatically reduced or lost in some neurons. However, Hoechst 33258 staining of the same sections revealed that these nuclei were preserved with an intact membrane. Labeling of neurons that had lost NeuN-positivity with antibodies against caspase-3-p20, which is constitutively not present but emerges in neurons after ischemia, disclosed that these neurons still preserved their integrity. Moreover, Western blots showed that NeuN protein levels were not decreased, suggesting that reduced NeuN antigenicity accounted for loss of immunoreactivity in this mild brain injury model. Supporting this idea, NeuN labeling was partially restored after antigenic retrieval. In conclusion, since NeuN immunoreactivity readily decreases after metabolic perturbations, reduced NeuN labeling should not be taken as an indicator of neuronal loss and, quantitative analysis based on NeuN-positivity should be used cautiously after central nervous system (CNS) injury.

Reperfusion-induced oxidative/nitrative injury to neurovascular unit after focal cerebral ischemia

BACKGROUND AND PURPOSE

Use of thrombolysis in stroke is limited by a short therapeutic window because delayed reperfusion may cause brain hemorrhage and edema. Available evidence suggests a role for superoxide, NO, and peroxynitrite in reperfusion-induced injury. However, depending on their cellular origin and interactions between them, these molecules may exert protective or deleterious actions, neither of which is characterized in the intact brain.

METHODS

Using fluorescent probes, we determined superoxide and peroxynitrite formation within neurons, astrocytes, and endothelium, and the association between oxidative/nitrative stress and vascular injury in mice brains subjected to 2-hour middle cerebral artery occlusion and 3 or 5 hours of reperfusion.

RESULTS

Both signals were colocalized, suggesting that the main source of peroxynitrite in the reperfused brain was a reaction between superoxide and NO. Superoxide and peroxynitrite formation was particularly intense in microvessels and astrocytic end-feet surrounding them, and overlapped with dense mitochondrial labeling. Sites of oxidative/nitrative stress on microvessels were colocalized with markers of vascular injury such as Evans blue (EB) leakage and matrix metalloproteinase-9 (MMP-9) expression, suggesting an association between peroxynitrite and microvascular injury. Supporting this idea, partial inhibition of endothelial NO synthesis at reperfusion with a low dose of L-nitroarginine (1 mg/kg IP) reduced 3-nitrotyrosine formation in microvessels and EB extravasation.

CONCLUSIONS

During reperfusion, intense superoxide, NO, and peroxynitrite formation on microvessels and surrounding end-feet may lead to cerebral hemorrhage and edema by disrupting microvascular integrity. Combination of thrombolysis with agents diminishing oxidative/nitrative stress may reduce reperfusion-induced injury and extend the therapeutic window for thrombolysis.

Is the cell death in mesial temporal sclerosis apoptotic?

PURPOSE

Mesial temporal sclerosis (MTS) is characterized by neuronal loss in the hippocampus. Studies on experimental models and patients with intractable epilepsy suggest that apoptosis may be involved in neuronal death induced by recurrent seizures.

METHODS

We searched evidence for apoptotic cell death in temporal lobes resected from drug-resistant epilepsy patients with MTS by using the terminal deoxynucleotidyl transferase (TdT) and digoxigenin-11-dUTP (TUNEL) method and immunohistochemistry for Bcl-2, Bax, and caspase-cleaved actin fragment, fractin. The temporal lobe specimens were obtained from 15 patients (six women and nine men; mean age, 29 +/- 8 years).

RESULTS

Unlike that in normal adult brain, we observed Bcl-2 immunoreactivity in some of the remaining neurons dispersed throughout the hippocampus proper as well as in most of the reactive astroglia. Bax immunopositivity was increased in almost all neurons. Fractin immunostaining, an indicator of caspase activity, was detected in approximately 10% of these neurons. Despite increased Bax expression and activation of caspases, we could not find evidence for DNA fragmentation by TUNEL staining. We also could not detect typical apoptotic changes in nuclear morphology by Hoechst-33258 or hematoxylin counterstaining.

CONCLUSIONS

These data suggest that either apoptosis is not involved in cell loss in MTS, or a very slow rate of cell demise may have precluded detecting TUNEL-positive neurons dying through apoptosis. Increased Bax expression and activation of caspases support the latter possibility.

Neuroscience data and tool sharing

The requirements for neuroinformatics to make a significant impact on neuroscience are not simply technical--the hardware, software, and protocols for collaborative research--they also include the legal and policy frameworks within which projects operate. This is not least because the creation of large collaborative scientific databases amplifies the complicated interactions between proprietary, for-profit R&D and public "open science." In this paper, we draw on experiences from the field of genomics to examine some of the likely consequences of these interactions in neuroscience. Facilitating the widespread sharing of data and tools for neuroscientific research will accelerate the development of neuroinformatics. We propose approaches to overcome the cultural and legal barriers that have slowed these developments to date. We also draw on legal strategies employed by the Free Software community, in suggesting frameworks neuroinformatics might adopt to reinforce the role of public-science databases, and propose a mechanism for identifying and allowing "open science" uses for data whilst still permitting flexible licensing for secondary commercial research.

How to construct a research project

A research proposal should start with defining its aims. A synopsis of the literature and observations that the hypothesis is grounded should be given together with relevant references. The significance of the project, expected contributions to the field should also be indicated. If available, preliminary data enhance the impact of the proposal. A detailed description of the methods and subjects to be used is an important part of the proposal. What data are to be collected, the method of collecting data, and selection criteria for subjects should be indicated. Variables and how the measurements will be taken, have to be defined precisely. Data processing and analysis tools should be described. Additionally, the expected time table, project cost, the ethical and legal issues should be included in the proposal. It should be kept in mind that a scientist's primary responsibility is to create conditions such that the hypothesis can be tested objectively rather than proving his hypothesis.

NEUROINFORMATICS: THE INTEGRATION OF SHARED DATABASES AND TOOLS TOWARDS INTEGRATIVE NEUROSCIENCE

There is significant interest amongst neuroscientists in sharing neuroscience data and analytical tools. The exchange of neuroscience data and tools between groups affords the opportunity to differently re-analyze previously collected data, encourage new neuroscience interpretations and foster otherwise uninitiated collaborations, and provide a framework for the further development of theoretically based models of brain function. Data sharing will ultimately reduce experimental and analytical error. Many small Internet accessible database initiatives have been developed and specialized analytical software and modeling tools are distributed within different fields of neuroscience. However, in addition large-scale international collaborations are required which involve new mechanisms of coordination and funding. Provided sufficient government support is given to such international initiatives, sharing of neuroscience data and tools can play a pivotal role in human brain research and lead to innovations in neuroscience, informatics and treatment of brain disorders. These innovations will enable application of theoretical modeling techniques to enhance our understanding of the integrative aspects of neuroscience. This article, authored by a multinational working group on neuroinformatics established by the Organization for Economic Co-operation and Development (OECD), articulates some of the challenges and lessons learned to date in efforts to achieve international collaborative neuroscience.