Kazuo Hashi

The Natural Course of Unruptured Cerebral Aneurysms in a Japanese Cohort

BACKGROUND The natural history of unruptured cerebral aneurysms has not been clearly defined. METHODS From January 2001 through April 2004, we enrolled patients with newly identified, unruptured cerebral aneurysms in Japan. Information on the rupture of aneurysms, deaths, and the results of periodic follow-up examinations were recorded. We included 5720 patients 20 years of age or older (mean age, 62.5 years; 68% women) who had saccular aneurysms that were 3 mm or more in the largest dimension and who initially presented with no more than a slight disability. RESULTS Of the 6697 aneurysms studied, 91% were discovered incidentally. Most aneurysms were in the middle cerebral arteries (36%) and the internal carotid arteries (34%). The mean (±SD) size of the aneurysms was 5.7±3.6 mm. During a follow-up period that included 11,660 aneurysm-years, ruptures were documented in 111 patients, with an annual rate of rupture of 0.95% (95% confidence interval [CI], 0.79 to 1.15). The risk of rupture increased with increasing size of the aneurysm. With aneurysms that were 3 to 4 mm in size as the reference, the hazard ratios for size categories were as follows: 5 to 6 mm, 1.13 (95% CI, 0.58 to 2.22); 7 to 9 mm, 3.35 (95% CI, 1.87 to 6.00); 10 to 24 mm, 9.09 (95% CI, 5.25 to 15.74); and 25 mm or larger, 76.26 (95% CI, 32.76 to 177.54). As compared with aneurysms in the middle cerebral arteries, those in the posterior and anterior communicating arteries were more likely to rupture (hazard ratio, 1.90 [95% CI, 1.12 to 3.21] and 2.02 [95% CI, 1.13 to 3.58], respectively). Aneurysms with a daughter sac (an irregular protrusion of the wall of the aneurysm) were also more likely to rupture (hazard ratio, 1.63; 95% CI, 1.08 to 2.48). CONCLUSIONS This study showed that the natural course of unruptured cerebral aneurysms varies according to the size, location, and shape of the aneurysm. (Funded by the Ministry of Health, Labor, and Welfare in Japan and others; UCAS Japan UMIN-CTR number, C000000418.).

Alteplase at 0.6 mg/kg for Acute Ischemic Stroke Within 3 Hours of Onset: Japan Alteplase Clinical Trial (J-ACT)

Background and Purpose— Based on previous studies comparing different recombinant tissue plasminogen activator (rt-PA) doses, we performed a clinical trial with 0.6 mg/kg, which is lower than the internationally approved dosage of 0.9 mg/kg, aiming to assess the efficacy and safety of alteplase in acute ischemic stroke for the Japanese. Methods— Our prospective, multicenter, single-arm, open-label trial was designed with a target sample size of 100 patients. The primary end points were the proportion of patients with a modified Rankin Scale (mRS) score of 0 to 1 at 3 months and the incidence of symptomatic intracranial hemorrhage (sICH) within 36 hours. Thresholds for these end points were determined by calculating 90% CIs of weighted averages derived from published reports. The protocol was defined according to the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA stroke study with slight modifications. Results— Among the 103 patients enrolled, 38 had an mRS of 0 to 1 at 3 months; this proportion (36.9%) exceeded the predetermined threshold of 33.9%. sICH within 36 hours occurred in 6 patients; this incidence (5.8%) was lower than the threshold of 9.6%. Conclusions— In patients receiving 0.6 mg/kg alteplase, the outcome and the incidence of sICH were comparable to published data for 0.9 mg/kg. These findings indicate that alteplase, when administered at 0.6 mg/kg to Japanese patients, might offer a clinical efficacy and safety that are compatible with data reported in North America and the European Union for a 0.9 mg/kg dose.

Transplantation of clonal neural precursor cells derived from adult human brain establishes functional peripheral myelin in the rat spinal cord.

We examined the myelin repair potential of transplanted neural precursor cells derived from the adult human brain from tissue removed during surgery. Sections of removed brain indicated that nestin-positive cells were found predominantly in the subventricular zone around the anterior horns of the lateral ventricle and in the dentate nucleus. Neurospheres were established and the nestin-positive cells were clonally expanded in EGF and bFGF. Upon mitogen withdrawal in vitro, the cells differentiated into neuron- and glia-like cells as distinguished by antigenic profiles; the majority of cells in culture showed neuronal and astrocytic properties with a small number of cells showing properties of oligodendrocytes and Schwann cells. When transplanted into the demyelinated adult rat spinal cord immediately upon mitogen withdrawal, the cells elicited extensive remyelination with a peripheral myelin pattern similar to Schwann cell myelination characterized by large cytoplasmic and nuclear regions, a basement membrane, and P0 immunoreactivity. The remyelinated axons conducted impulses at near normal conduction velocities. This suggests that a common neural progenitor cell for CNS and PNS previously described for embryonic neuroepithelial cells may be present in the adult human brain and that transplantation of these cells into the demyelinated spinal cord results in functional remyelination.

Transplantation of Human Olfactory Ensheathing Cells Elicits Remyelination of Demyelinated Rat Spinal Cord

Human olfactory ensheathing cells (OECs) were prepared from adult human olfactory nerves, which were removed during surgery for frontal base tumors, and were transplanted into the demyelinated spinal cord of immunosuppressed adult rats. Extensive remyelination was observed in the lesion site: In situ hybridization using a human DNA probe (COT‐1) indicated a similar number of COT‐1‐positive cells and OEC nuclei within the repaired lesion. The myelination was of a peripheral type with large nuclei and cytoplasmic regions surrounding the axons, characteristic of Schwann cell and OEC remyelination. These results provide evidence that adult human OECs are able to produce Schwann cell‐like myelin sheaths around demyelinated axons in the adult mammalian CNS in vivo. GLIA 30:209–218, 2000.

Transplantation of an Acutely Isolated Bone Marrow Fraction Repairs Demyelinated Adult Rat Spinal Cord Axons

The potential of bone marrow cells to differentiate into myelin‐forming cells and to repair the demyelinated rat spinal cord in vivo was studied using cell transplantation techniques. The dorsal funiculus of the spinal cord was demyelinated by x‐irradiation treatment, followed by microinjection of ethidium bromide. Suspensions of a bone marrow cell fraction acutely isolated from femoral bones in LacZ transgenic mice were prepared by centrifugation on a density gradient (Ficoll‐Paque) to remove erythrocytes, platelets, and debris. The isolated cell fraction contained hematopoietic and nonhematopoietic stem and precursor cells and lymphocytes. The cells were transplanted into the demyelinated dorsal column lesions of immunosuppressed rats. An intense blue β‐galactosidase reaction was observed in the transplantation zone. The genetically labeled bone marrow cells remyelinated the spinal cord with predominately a peripheral pattern of myelination reminiscent of Schwann cell myelination. Transplantation of CD34+ hematopoietic stem cells survived in the lesion, but did not form myelin. These results indicate that bone marrow cells can differentiate in vivo into myelin‐forming cells and repair demyelinated CNS. GLIA 35:26–34, 2001.

A therapeutic window for intravenous administration of autologous bone marrow after cerebral ischemia in adult rats.

The primary objective of this study was to test the hypothesis that intravenous administration of autologous bone marrow cells could improve functional recovery after middle cerebral artery occlusion (MCAO) for 45 min in the rat and to determine specific time windows for efficacy. Mononuclear cells from autologous bone marrow were transfected with the LacZ reporter gene, and injected intravenously into rats at 3-72 h after induction of MCAO. Histological analysis of the ischemic lesion at 14 days after transplantation revealed reduced ischemic lesion volume. Lesion volume was 250+/-45 mm(3) (n=6) after MCAO without cell transplantation. Lesions were minimally detected by absence of 2,3,5-triphenyltetrazolium chloride (TTC) staining when bone marrow cells were infused 3 h after lesion induction. Lesions were clearly detected beginning with the 6-h postlesion group and became progressively larger at 12, 24 and 72 h (80+/-25, 140+/-18, and 180+/-22 mm(3), respectively; n=6 for each group). Transplanted LacZ(+) bone marrow cells accumulated extensively in and around the ischemic lesions, and immunohistochemistry suggests some neuronal and glial lineage differentiation. Behavioral testing (Morris water maze and Treadmill stress test) indicated greater functional recovery in the treated group. These findings suggest that early intervention with intravenous administration of autologous mononuclear cells from bone marrow can reduce lesion size in the MCAO model in the rat, and improve functional outcome.

Alteplase at 0.6 mg/kg for Acute Ischemic Stroke Within 3 Hours of Onset

Background and Purpose— Based on previous studies comparing different recombinant tissue plasminogen activator (rt-PA) doses, we performed a clinical trial with 0.6 mg/kg, which is lower than the internationally approved dosage of 0.9 mg/kg, aiming to assess the efficacy and safety of alteplase in acute ischemic stroke for the Japanese. Methods— Our prospective, multicenter, single-arm, open-label trial was designed with a target sample size of 100 patients. The primary end points were the proportion of patients with a modified Rankin Scale (mRS) score of 0 to 1 at 3 months and the incidence of symptomatic intracranial hemorrhage (sICH) within 36 hours. Thresholds for these end points were determined by calculating 90% CIs of weighted averages derived from published reports. The protocol was defined according to the National Institute of Neurological Disorders and Stroke (NINDS) rt-PA stroke study with slight modifications. Results— Among the 103 patients enrolled, 38 had an mRS of 0 to 1 at 3 months; this proportion (36.9%) exceeded the predetermined threshold of 33.9%. sICH within 36 hours occurred in 6 patients; this incidence (5.8%) was lower than the threshold of 9.6%. Conclusions— In patients receiving 0.6 mg/kg alteplase, the outcome and the incidence of sICH were comparable to published data for 0.9 mg/kg. These findings indicate that alteplase, when administered at 0.6 mg/kg to Japanese patients, might offer a clinical efficacy and safety that are compatible with data reported in North America and the European Union for a 0.9 mg/kg dose.

Comparative analysis of remyelinating potential of focal and intravenous administration of autologous bone marrow cells into the rat demyelinated spinal cord

The remyelinating potential of autologous bone marrow cells was studied after direct injection and following intravenous injection into rats with a demyelinated lesion in the spinal cord. Both focal and intravenous injections of acutely isolated mononuclear bone marrow cell fractions resulted in varying degrees of remyelination. Suspensions of bone marrow cells collected from the same rat were delivered at varied concentrations (102 to 105 for direct injection and 104 to 107 for i.v. injections). The lesions were examined histologically 3 weeks after transplantation. Light microscopic examination revealed remyelination in the dorsal funiculus with both injection protocols, but the extent of remyelination was proportional to the number of injected cells. To attain the same relative density of remyelination achieved by direct injection, intravenous administration of cells required delivery of substantially more cells (two orders of magnitude). However, the availability of autologous bone marrow cells in large number and the potential for systemically delivering cells to target lesion areas without neurosurgical intervention suggest the potential utility of intravenous cell delivery as a prospective therapeutic approach in demyelinating disease.

Results of reoperation for failed microvascular decompression

SummaryAmong 64 patients with hemifacial spasm (HFS) and 60 with trigeminal neuralgia (TN) treated by microvascular decompression (MVD), repeated MVD performed on 3 cases with HFS resulted in the absence of spasm in all cases. In 7 cases with TN, this technique resulted in complete remission in 2, recurrence in 3, and no pain relief in 2 cases. MVD was more effective on HFS than on TN in repeated procedures as well as for initial treatment. The cause of recurrence of HFS was attributed to the inadequate cushion effect of muscle as a prosthesis, while that for TN was suspected to be related more to post-operative fibrotic adhesions formed around the fifth nerve.

Autologous transplantation of expanded neural precursor cells into the demyelinated monkey spinal cord

The objective of this study was to establish if neural precursor cells could safely be developed from biopsy of the subventricular zone (SVZ) in the non-human primate (marmoset), and to determine their myelinating potential after autologous transplantation into a demyelinated lesion. Small amounts of tissue were safely collected from the subventricular-subependymal zone of the adult primate brain under ultrasonography without any neurological deficit. Neural precursor cells were isolated and expanded in the presence of mitogen in vitro. The dorsal columns of the adult marmoset spinal cord were demyelinated by X-irradiation and intraspinal injections of ethidium bromide in the center of the radiation field. Cell suspensions of the neural precursors were microinjected through a micropipette into the demyelinated lesion site in the spinal cord. Lesions were histologically examined 3 weeks after transplantation. Light and electron microscopic examination of plastic embedded sections revealed a significant number of myelinating profiles in the transplantation zone; no myelination was observed in control lesions. The myelinated axons had predominantly peripheral patterns of myelination. These results demonstrate that autologous transplantation of neural precursor cells in the adult nonhuman primate can remyelinate demyelinated central nervous system (CNS) axons, thus suggesting the potential utility of such an approach in demyelinating lesions in humans.