Toru Iwama

Evidence for white matter disruption in traumatic brain injury without macroscopic lesions

Background: Non-missile traumatic brain injury (nmTBI) without macroscopically detectable lesions often results in cognitive impairments that negatively affect daily life. Aim: To identify abnormal white matter projections in patients with nmTBI with cognitive impairments using diffusion tensor magnetic resonance imaging (DTI). Methods: DTI scans of healthy controls were compared with those of 23 patients with nmTBI who manifested cognitive impairments but no obvious neuroradiological lesions. DTI was comprised of fractional anisotropy analysis, which included voxel-based analysis and confirmatory study using regions of interest (ROI) techniques, and magnetic resonance tractography of the corpus callosum and fornix. Results: A decline in fractional anisotropy around the genu, stem and splenium of the corpus callosum was shown by voxel-based analysis. Fractional anisotropy values of the genu (0.47), stem (0.48), and splenium of the corpus callosum (0.52), and the column of the fornix (0.51) were lower in patients with nmTBI than in healthy controls (0.58, 0.61, 0.62 and 0.61, respectively) according to the confirmatory study of ROIs. The white matter architecture in the corpus callosum and fornix of patients with nmTBI were seen to be coarser than in the controls in the individual magnetic resonance tractography. Conclusions: Disruption of the corpus callosum and fornix in patients with nmTBI without macroscopically detectable lesions is shown. DTI is sensitive enough to detect abnormal neural fibres related to cognitive dysfunction after nmTBI.

Comparison of mesenchymal stem cells from adipose tissue and bone marrow for ischemic stroke therapy.

BACKGROUND AIMS Transplantation of mesenchymal stromal cells (MSC) derived from bone marrow (BM) or adipose tissue is expected to become a cell therapy for stroke. The present study compared the therapeutic potential of adipose-derived stem cells (ASC) with that of BM-derived stem cells (BMSC) in a murine stroke model. METHODS ASC and BMSC were isolated from age-matched C57BL/6J mice. These MSC were analyzed for growth kinetics and their capacity to secrete trophic factors and differentiate toward neural and vascular cell lineages in vitro. For in vivo study, ASC or BMSC were administrated intravenously into recipient mice (1 × 10(5) cells/mouse) soon after reperfusion following a 90-min middle cerebral artery occlusion. Neurologic deficits, the degree of infarction, expression of factors in the brain, and the fate of the injected cells were observed. RESULTS ASC showed higher proliferative activity with greater production of vascular endothelial cell growth factor (VEGF) and hepatocyte growth factor (HGF) than BMSC. Furthermore, in vitro conditions allowed ASC to differentiate into neural, glial and vascular endothelial cells. ASC administration showed remarkable attenuation of ischemic damage, although the ASC were not yet fully incorporated into the infarct area. Nonetheless, the expression of HGF and angiopoietin-1 in ischemic brain tissue was significantly increased in ASC-treated mice compared with the BMSC group. CONCLUSIONS Compared with BMSC, ASC have great advantages for cell preparation because of easier and safer access to adipose tissue. Taken together, our findings suggest that ASC would be a more preferable source for cell therapy for brain ischemia than BMSC.

Epidermal Growth Factor Plays a Crucial Role in Mitogenic Regulation of Human Brain Tumor Stem Cells

A cancer stem cell population in malignant brain tumors takes an essential part in brain tumor initiation, growth, and recurrence. Growth factors, such as epidermal growth factor, fibroblast growth factor-2, vascular endothelial growth factor, platelet-derived growth factor, and hepatocyte growth factor, are shown to support the proliferation of neural stem cells and also may play key roles in gliomagenesis. However, the responsible growth factor(s), which controls maintenance of brain tumor stem cells, is not yet uncovered. We have established three cancer stem cell lines from human gliomas. These cells were immunoreactive with the neuronal progenitor markers, nestin and CD133, and established tumors that closely resembled the features of original tumor upon transplantation into mouse brain. Three cell lines retained their self-renewal ability and proliferation only in the presence of epidermal growth factor (>2.5 ng/ml). In sharp contrast, other growth factors, including fibroblast growth factor-2, failed to support maintenance of these cells. The tyrosine kinase inhibitors of epidermal growth factor signaling (AG1478 and gefitinib) suppressed the proliferation and self-renewal of these cells. Gefitinib inhibited phosphorylation of epidermal growth factor receptor as well as Akt kinase and extracellular signal-regulated kinase 1/2. Flow cytometric analysis revealed that epidermal growth factor concentration-dependently increased the population of CD133-positive cells. Gefitinib significantly reduced CD133-positive fractions and also induced their apoptosis. These results indicate that maintenance of human brain tumor stem cells absolutely requires epidermal growth factor and that tyrosine kinase inhibitors of epidermal growth factor signaling potentially inhibit proliferation and induce apoptosis of these cells.

The Experimental and Clinical Pharmacology of Propofol, an Anesthetic Agent with Neuroprotective Properties

Propofol (2,6‐diisopropylphenol) is a versatile, short‐acting, intravenous (i.v.) sedative‐hypnotic agent initially marketed as an anesthetic, and now also widely used for the sedation of patients in the intensive care unit (ICU). At the room temperature propofol is an oil and is insoluble in water. It has a remarkable safety profile. Its most common side effects are dose‐dependent hypotension and cardiorespiratory depression. Propofol is a global central nervous system (CNS) depressant. It activates γ‐aminobutyric acid (GABAA) receptors directly, inhibits the N‐methyl‐d‐aspartate (NMDA) receptor and modulates calcium influx through slow calcium‐ion channels. Furthermore, at doses that do not produce sedation, propofol has an anxiolytic effect. It has also immunomodulatory activity, and may, therefore, diminish the systemic inflammatory response believed to be responsible for organ dysfunction. Propofol has been reported to have neuroprotective effects. It reduces cerebral blood flow and intracranial pressure (ICP), is a potent antioxidant, and has antiinflammatory properties. Laboratory investigations revealed that it might also protect brain from ischemic injury. Propofol formulations contain either disodium edetate (EDTA) or sodium metabisulfite, which have antibacterial and antifungal properties. EDTA is also a chelator of divalent ions such as calcium, magnesium, and zinc. Recently, EDTA has been reported to exert a neuroprotective effect itself by chelating surplus intracerebral zinc in an ischemia model. This article reviews the neuroprotective effects of propofol and its mechanism of action.

The use of frozen autogenous bone flaps in delayed cranioplasty revisited.

OBJECTIVETo reevaluate the use of frozen autogenous bone flaps for patients undergoing delayed cranioplasty. METHODSIn the past 12 years, 49 patients have undergone delayed cranioplasty using frozen autogenous bone flaps. Bone flaps removed during the initial operation were sealed in three sterilized vinyl bags and stored at −35°C (n = 37) or −84°C (n = 12) for 4 to 168 days (mean, 50.6 d). The bone flaps were thawed at room temperature and replaced in their original positions. After cranioplasty, we monitored resorption of the bone flaps with computed tomography and evaluated the clinical and aesthetic results. Follow-up periods ranged from 14 to 147 months (mean, 59.2 mo). RESULTSFor 47 patients (95.9%), there were no complications during the follow-up period; there was slight thinning of the bone flap in some cases, but clinical and aesthetic results were highly satisfactory. Resorption was observed for a 12-year-old boy who had undergone cranioplasty, using two pieces of bone flap, 66 days after the initial operation. A 14-year-old boy with a cerebral contusion experienced a bone flap infection. Both patients underwent a second cranioplasty procedure, with ceramic plates. CONCLUSIONThe clinical and aesthetic results of delayed cranioplasty using frozen autogenous bone flaps were satisfactory. The most important factor for success was excellent contiguity between the flap and the bone edge.

Cell permeable ROS scavengers, Tiron and Tempol, rescue PC12 cell death caused by pyrogallol or hypoxia/reoxygenation

The role of superoxide anion (O(2)*-) in neuronal cell injury induced by reactive oxygen species (ROS) was examined in PC12 cells using pyrogallol (1,2,3-benzenetrior), a donor to release O(2)*-. Pyrogallol induced PC12 cell death at concentrations, which evidently increased intracellular O(2)*-, as assessed by O(2)(*-)-sensitive fluorescent precursor hydroethidine (HEt). Caspase inhibitors, Z-VAD-FMK and Z-Asp-CH(2)-DCB, failed to protect cells from injury caused by elevation of intracellular O(2)*-, although these inhibitors had effects on hypoxia- or hydrogen peroxide (H(2)O(2))-induced PC12 cell death. Two known O(2)*- scavengers, Tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid) and Tempol (4-hydroxy-2,2,6,6-tetramethylpiperydine-1-oxyl) rescued PC12 cells from pyrogallol-induced cell death. Hypoxia/reoxygenation injury of PC12 cells was also blocked by Tiron and Tempol. Further understanding of the underlying mechanism of the protective effects of these radical scavengers reducing intracellular O(2)*- on neuronal cell death may lead to development of new therapeutic treatments for hypoxic/ischemic brain injury.

Relationship between regional cerebral metabolism and consciousness disturbance in traumatic diffuse brain injury without large focal lesions: an FDG-PET study with statistical parametric mapping analysis

Background: The cerebral metabolism of patients in the chronic stage of traumatic diffuse brain injury (TDBI) has not been fully investigated. Aim: To study the relationship between regional cerebral metabolism (rCM) and consciousness disturbance in patients with TDBI. Methods: 52 patients with TDBI in the chronic stage without large focal lesions were enrolled, and rCM was evaluated by fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) with statistical parametric mapping (SPM). All the patients were found to have disturbed consciousness or cognitive function and were divided into the following three groups: group A (n = 22), patients in a state with higher brain dysfunction; group B (n = 13), patients in a minimally conscious state; and group C (n = 17), patients in a vegetative state. rCM patterns on FDG-PET among these groups were evaluated and compared with those of normal control subjects on statistical parametric maps. Results: Hypometabolism was consistently indicated bilaterally in the medial prefrontal regions, the medial frontobasal regions, the cingulate gyrus and the thalamus. Hypometabolism in these regions was the most widespread and prominent in group C, and that in group B was more widespread and prominent than that in group A. Conclusions: Bilateral hypometabolism in the medial prefrontal regions, the medial frontobasal regions, the cingulate gyrus and the thalamus may reflect the clinical deterioration of TDBI, which is due to functional and structural disconnections of neural networks rather than due to direct cerebral focal contusion.

Discrepancy between lesion distributions on methionine PET and MR images in patients with glioblastoma multiforme: insight from a PET and MR fusion image study

Objective: To examine 11C-methyl methionine (MET) accumulation on positron emission tomographic (PET) imaging of glioblastoma multiforme to determine the distribution of metabolic abnormality compared with magnetic resonance imaging (MRI). Methods: Contemporaneous MRI was superimposed on corresponding MET-PET images in 10 patients with newly diagnosed glioblastoma multiforme before treatment. Differences between the extended area of MET accumulation on PET imaging (MET area), the gadolinium (Gd) enhanced area on T1 weighted images (Gd area), and the abnormal high signal intensity area on T2 weighted images (T2-high area) were assessed. Results: The MET area was larger than the Gd area and included the entire Gd area. The discrepancy in volume between the MET and Gd areas became greater with increasing tumour diameter. On average, 58.6% of the MET area was located within the Gd area, 90.1% within 10 mm outside the Gd area, 98.1% within 20 mm, and 99.8% within 30 mm. A newly developed Gd area had emerged in five of the 10 cases up to the time of study. In three of the five cases this was in the MET area even after complete surgical resection of the Gd area on the initial MRI; in the remaining two it originated in the residual Gd area after surgery. In all cases, the T2-high area was larger than the MET area. The MET area extended partly beyond the T2-high area in nine cases, and was completely within it in one. Conclusions: Glioblastoma multiforme cells may extend over the Gd area and more widely with increasing tumour size on Gd-MRI. The T2-high area includes the greater part of the tumour but not its entire area. The methods reported may be useful in planning surgical resection, biopsy, or radiosurgery.

Fasudil, a Rho kinase (ROCK) inhibitor, protects against ischemic neuronal damage in vitro and in vivo by acting directly on neurons

BACKGROUND AND PURPOSE Recently, fasudil, a Rho kinase (ROCK) inhibitor, was reported to prevent cerebral ischemia in vivo by increasing cerebral blood flow and inhibiting inflammatory responses. However, it is uncertain whether a ROCK inhibitor can directly protect neurons against ischemic damage. Our purpose was to evaluate both the involvement of ROCK activity in ischemic neuronal damage and any direct neuroprotective effect of fasudil against cerebral infarction. METHODS In vivo, focal cerebral ischemia was induced by permanent middle cerebral artery occlusion in mice, and the resulting infarction was evaluated 24 h later. ROCK expression and activity were assessed using Western blotting and immunohistochemistry. In vitro, the effects of fasudil and hydroxyfasudil (a main metabolite of fasudil) were examined on oxygen-glucose deprivation (OGD)-induced PC12 cell death and on glutamate-induced neurotoxicity in primary cerebral neuronal culture. RESULTS ROCK expression and activity increased in the striatum, especially in axons, in the early phase of ischemia. Fasudil reduced this ROCK activity and protected against cerebral infarction in vivo. Hydroxyfasudil inhibited OGD-induced PC12 cell death, and fasudil and hydroxyfasudil each attenuated glutamate-induced neurotoxicity in vitro. CONCLUSIONS These findings indicate that ROCK plays a pivotal role in the mechanism underlying ischemic neuronal damage and that a direct effect of fasudil on neurons may be partly responsible for its protective effects against such damage.

Spinal injuries in snowboarders: risk of jumping as an integral part of snowboarding

BACKGROUND The purpose of this study was to clarify the occurrence rate and characteristics of spinal injuries caused by snowboarding that were sustained at the Okumino skiing area in Gifu Prefecture, Japan, from 1988 to 2000. METHODS This study was a retrospective review of 13,490 cases of snowboard- or ski-related injury treated at Sumi Memorial Hospital over this period. RESULTS A total of 7,188 patients sustained snowboard-related injuries, and 238 of these had spinal injuries caused by snowboarding (3.3%), whereas 6,302 patients sustained ski-related injuries, and 86 of these had spinal injuries caused by skiing (1.4%). Although there were no significant differences in the difficulty of slope, location of vertebral fracture, or spinal cord injury between snowboarders and skiers, the incidence of transverse process fractures was significantly higher in snowboard-related than in skiing-related injury (p < 0.05). In addition, there was a significantly higher incidence of spinal injury among beginner snowboarders than among beginner skiers (p = 0.04). Furthermore, intermediate or expert snowboarders were more likely to be injured because of jumping than beginners (p < 0.001), whereas about 70% of spinal injuries caused by skiing resulted from a simple fall. CONCLUSION Spinal injuries sustained while snowboarding are increasing considerably in incidence and are characterized as complex injuries. We must educate young snowboarders of the risk of this sport, to prevent these serious injuries.