Manabu Minami

Proliferating Progenitor Cells: A Required Cellular Element for Induction of Ischemic Tolerance in the Brain

Permanent cerebral blood flow reduction results in brain injury (stroke), whereas transient ischemic stress results in preconditioning, which can ameliorate the extent of irreversible brain injury from subsequent ischemia—the phenomena of ischemic tolerance. Neurogenesis in the brain occurs after both ischemic injury and the brief ischemia resulting in preconditioning. As neurogenesis is regarded as having an intrinsic neuroprotective role in the brain, we investigated the possible role of these endogenous progenitor cells in the induction of ischemic tolerance. Methylazoxymethanol acetate (MAM) was injected in wild-type mice to attenuate precursor cell proliferation and ganciclovir was used to diminish newly generated cells in GFAP/HSV-TK mice. Both MAM and ganciclovir significantly attenuated ischemia-induced progenitor cell proliferation in the subventricular zone, dentate gyrus, penumbra, and corpus callosum as quantified by 5-bromo-2′-deoxyuridine- or Ki-67-positive cells. Attenuation of ischemia-induced progenitor cell proliferation in the brain blocked the induction of ischemic tolerance. Further the number of TUNEL (TdT-mediated dUTP nick end labeling)-positive cells was considerably increased in MAM-treated animals, whereas MAM did not cause cell death in sham-operated controls. The results of this study suggest a role for endogenous progenitors in the protective effect of ischemic tolerance.

Spinal dural arteriovenous fistula with hematomyelia caused by intraparenchymal varix of draining vein

BACKGROUND CONTEXT Hemorrhage that results from spinal dural arteriovenous fistula (Type I arteriovenous malformation [AVM]) is uncommon. There are some reports of subarachnoid hemorrhage and subdural hematoma caused by Type I spinal AVM, but there are few reported cases of hematomyelia caused by spinal dural arteriovenous fistula. PURPOSE To describe an interesting patient who had hematomyelia caused by a dural arteriovenous fistula (Type I spinal AVM). STUDY DESIGN A case report. METHODS We present a case of a 51-year-old man who presented acute onset epigastric pain, paraplegia, and sensory loss below his nipples. Magnetic resonance imaging and selective spinal angiogram demonstrated hematomyelia, subarachnoid hemorrhage, and spinal arteriovenous fistula fed by the right Th7 intercostal artery. By laminotomy of Th6-8, the varix-like draining vein and intramedurally hematoma were partially removed and the arterial supply was interrupted by coagulation of the right Th7 segmental artery. RESULTS One month after surgery, he regained movement against gravity at the left ankle and toe but no functionally significant improvement. CONCLUSIONS It must be kept in mind that spinal dural arteriovenous fistulas (Type I spinal AVM) has possibility of hematomyelia origin, despite the fact that it is extremely rare.