Shigeru Nishizawa

Cerebral vasospasm following subarachnoid hemorrhage: time for a new world of thought

Abstract Objective: Delayed cerebral vasospasm has long been recognized as an important cause of poor outcome after an otherwise successful treatment of a ruptured intracranial aneurysm, but it remains a pathophysiological enigma despite intensive research for more than half a century. Method: Summarized in this review are highlights of research from North America, Europe and Asia reflecting recent advances in the understanding of delayed ischemic deficit. Result: It will focus on current accepted mechanisms and on new frontiers in vasospasm research. Conclusion: A key issue is the recognition of events other than arterial narrowing such as early brain injury and cortical spreading depression and of their contribution to overall mortality and morbidity.

Role of Wnt pathway in medulloblastoma oncogenesis

To clarify the roles of Wnt pathway in medulloblastoma oncogenesis, immunohistochemical staining of β‐catenin and Wnt‐1 and genomic analyses of CTNNB1 (β‐catenin) and AXIN1 (axin 1) were examined in 23 sporadic cases. Accumulation of β‐catenin in tumor cells was immunohistochemically proven in 5 cases; 2 cases showed positive immunoreactivity for Wnt‐1 and another 2 showed mutation of either CTNNB1 or AXIN1. AXIN1 mutation was in exon 3, corresponding to GSK‐3β binding site and CTNNB1 mutation was in exon 3, corresponding to its phosphorylation site. Disruption of these proteins could result in upregulation of the Wnt signaling and accumulation of β‐catenin, followed by cell proliferation and medulloblastoma oncogenesis.

Role of interleukin-1beta in early brain injury after subarachnoid hemorrhage in mice.

Background and Purpose— The role of interleukin (IL)-1&bgr; remains unknown in early brain injury (EBI) after subarachnoid hemorrhage (SAH), although IL-1&bgr; has been repeatedly reported to increase in the brain and cerebrospinal fluid. The aim of this study is to examine the effects of IL-1&bgr; inactivation on EBI after SAH in mice. Methods— The endovascular perforation model of SAH was produced and 112 mice were assigned to sham, SAH+ vehicle, and SAH+ N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-CMK, 6 and 10 mg/kg) groups. Ac-YVAD-CMK, a selective inhibitor of IL-1&bgr; converting enzyme, or vehicle was administered intraperitoneally 1 hour post-SAH. EBI was assessed in terms of mortality within 24 hours, neurological scores, brain water content at 24 and 72 hours, Evans blue dye extravasation and Western blot for IL-1&bgr;, c-Jun N-Terminal kinase (JNK), matrix metalloproteinase (MMP)-9, and zonula occludens (ZO)-1 at 24 hours after SAH. Results— High-dose (10 mg/kg) but not low-dose (6 mg/kg) treatment group significantly improved neurological scores, mortality, brain water content, and Evans blue dye extravasation compared with the vehicle group. Although both dosages of Ac-YVAD-CMK attenuated the mature IL-1&bgr; induction, only high-dose treatment group significantly inhibited the phosphorylation of JNK, MMP-9 induction, and ZO-1 degradation. Conclusion— IL-1&bgr; activation may play an important role in the pathogenesis of EBI after SAH. The neurovascular protection of Ac-YVAD-CMK may be provided by the inhibition of JNK-mediated MMP-9 induction and the consequent preservation of tight junction protein ZO-1.

Role of Interleukin-1β in Early Brain Injury After Subarachnoid Hemorrhage in Mice

Background and Purpose— The role of interleukin (IL)-1&bgr; remains unknown in early brain injury (EBI) after subarachnoid hemorrhage (SAH), although IL-1&bgr; has been repeatedly reported to increase in the brain and cerebrospinal fluid. The aim of this study is to examine the effects of IL-1&bgr; inactivation on EBI after SAH in mice. Methods— The endovascular perforation model of SAH was produced and 112 mice were assigned to sham, SAH+ vehicle, and SAH+ N-Ac-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-CMK, 6 and 10 mg/kg) groups. Ac-YVAD-CMK, a selective inhibitor of IL-1&bgr; converting enzyme, or vehicle was administered intraperitoneally 1 hour post-SAH. EBI was assessed in terms of mortality within 24 hours, neurological scores, brain water content at 24 and 72 hours, Evans blue dye extravasation and Western blot for IL-1&bgr;, c-Jun N-Terminal kinase (JNK), matrix metalloproteinase (MMP)-9, and zonula occludens (ZO)-1 at 24 hours after SAH. Results— High-dose (10 mg/kg) but not low-dose (6 mg/kg) treatment group significantly improved neurological scores, mortality, brain water content, and Evans blue dye extravasation compared with the vehicle group. Although both dosages of Ac-YVAD-CMK attenuated the mature IL-1&bgr; induction, only high-dose treatment group significantly inhibited the phosphorylation of JNK, MMP-9 induction, and ZO-1 degradation. Conclusion— IL-1&bgr; activation may play an important role in the pathogenesis of EBI after SAH. The neurovascular protection of Ac-YVAD-CMK may be provided by the inhibition of JNK-mediated MMP-9 induction and the consequent preservation of tight junction protein ZO-1.

Monocarboxylate transporters 1 and 4 are involved in the invasion activity of human lung cancer cells.

Cancer cells show constitutive upregulation of glycolysis, and the concentration of lactate thus produced correlates with prognosis. Here, we examined whether lactate concentration and lactate transporter expression are related to migration and invasion activity. We found that the expression of the monocarboxylate transporters MCT1 and MCT4, but not MCT5, in human lung cancer cell lines was significantly correlated with invasiveness. To clarify the effects of MCT1 and MCT4 expression on invasion, we performed migration and invasion assays after transfection with siRNA specific for MCT1 or MCT4. Knockdown of MCT1 or MCT4 did not influence cell migration but reduced invasion; this was also observed for knockdown of the lactate transporter‐associated protein basigin. We also demonstrated that both expression and activity of MMP9 and MMP2 were not correlated with invasion activity and not regulated by MCT1, MCT4 and basigin. Furthermore, the addition of lactate did not increase migration and invasion activity, but low concentration of 4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid (DIDS), a general anion channel blocker, as well as other MCT inhibitors quercetin and simvastatin, inhibited cell invasion without influencing migration activity and the cellular expression of MCT1 and MCT4. This is the first report suggesting that lactate transporters are involved in human cancer cell invasiveness. As such, these proteins may be promising targets for the prevention of cancer invasion and metastasis. (Cancer Sci 2011; 102: 1007–1013)

Subthalamic nucleus stimulation for gait disturbance in Parkinson's disease.

OBJECTIVE A preliminary study of subthalamic nucleus (STN) stimulation was performed to determine its applicability for the treatment of gait and postural disturbances in Parkinsons disease. METHODS Five Parkinsons disease patients with freezing gait and postural instability were selected for this study. Their ages ranged from 60 to 73 years (mean+/-standard deviation, 65.6+/-4.8 years). Semi-microelectrode recording was used to identify the STN and to place a chronic electrical stimulation electrode within the right STN in all patients. The Unified Parkinsons Disease Rating Scale and the modified Hoehn and Yahr Staging Scale were used to assess patients in on- and off-drug conditions before surgery and 3 months after surgery. RESULTS The scores on the Hoehn and Yahr Staging Scale and the total Unified Parkinsons Disease Rating Scale for akinesia (P < 0.05), gait (P < 0.05), and gait and posture (P < 0.01) in off-drug on-stimulation conditions significantly improved over the preoperative and postoperative off-drug off-stimulation conditions (analysis of variance [ANOVA], P < 0.01). Improvement over the preoperative scores was 24% on the Hoehn and Yahr Staging Scale, 43.6% on the total Unified Parkinsons Disease Rating Scale, 33.4% for akinesia, 36.6% for gait, and 38.7% for gait and posture. However, stimulation in the on-drug phase did not show a significant difference compared with pre- and postoperative conditions (ANOVA, P > 0.05). Comparisons between preoperative on-drug and postoperative off-drug on-stimulation conditions revealed that there were no significant differences in the scores, except for gait (ANOVA, P < 0.05). The scores on subscales for falling, freezing, walking, and gait in off-drug on-stimulation conditions were significantly improved over the scores for preoperative and postoperative off-stimulation (ANOVA, P < 0.05), but the score for postural stability remained unchanged. CONCLUSION Our findings showed that STN stimulation effectively alleviates freezing gait and improves walking to its status during the preoperative on-drug phase and can be applied for treatment of Parkinsons disease patients with these symptoms.

Cyclosporine A reduces cerebral vasospasm after subarachnoid hemorrhage in dogs.

The double subarachnoid hemorrhage canine model was used to test the prophylactic value of immunosuppression in the prevention of cerebral vasospasm after subarachnoid hemorrhage. Dogs treated with cyclosporine A following the regimen prescribed for organ transplant procedures in patients showed a significant reduction in the severity of angiographic constriction of cerebral arteries. While basilar artery diameter after double experimental subarachnoid hemorrhage in a series of untreated dogs (n = 34) averaged 65% of baseline diameter, arterial diameter in dogs treated prophylactically (n = 18) with 6 mg/kg/day cyclosporine A and adjunct low-dose steroid averaged 80% of baseline diameter, for a mean reduction in the severity of chronic arterial constriction of 42%. More important than the average effect, however, is the statistical observation that this mean improvement was obtained primarily by a dramatic reduction in the incidence of severe cerebral vasospasm, the situation most likely to account for morbidity and mortality after aneurysmal rupture.

Incidentally identified syringomyelia associated with Chiari I malformations: is early interventional surgery necessary?

OBJECTIVEThe purpose of this study was to analyze clinical data and magnetic resonance imaging (MRI) findings for patients with asymptomatic, incidentally identified syringomyelia associated with Chiari I malformations who were monitored for more than 10 years, and to clarify the natural history of these lesions. METHODSThe clinical records of nine patients who had not been surgically treated and were regularly subjected to neurological and MRI examinations were analyzed. In MRI studies, the axial diameter of the syrinx at the widest level, the longitudinal extent of the syrinx, and the extent of tonsillar herniation into the spinal canal were analyzed. As a control, MRI findings for 11 patients with symptomatic syringomyelia associated with Chiari I malformations who had been surgically treated were also analyzed, and these MRI parameters were statistically compared between the asymptomatic and symptomatic groups. RESULTSOne patient underwent surgery, because of neurological changes, 7 years after the first visit. None of the remaining patients demonstrated any neurological change during the follow-up period (11.2 ± 0.7 yr), and all of them have been faring well without surgery. No statistically significant differences in MRI findings between the asymptomatic and symptomatic groups were observed. CONCLUSIONThe long-term clinical courses of patients with asymptomatic, incidentally identified syringomyelia associated with Chiari I malformations were observed to be benign. MRI parameters did not provide predictable values to recommend interventional surgery. Unless changes in neurological or MRI findings are detected, early interventional surgery is not necessary.

Chronological Changes of Arterial Diameter, cGMP, and Protein Kinase C in the Development of Vasospasm

BACKGROUND AND PURPOSE We hypothesized that nitric oxide exerts a negative feedback control on protein kinase C (PKC) activation, and the disturbance of the feedback control after subarachnoid hemorrhage results in vasospasm due to PKC activation. This study was undertaken to verify this hypothesis. METHODS Different dogs were prepared for three separate experiments: measurement of the angiographic diameter of the basilar artery and determination of cGMP and PKC activity in vascular smooth muscle cells. In each experiment, two models were used: the single-hemorrhage model for mild vasospasm and the two-hemorrhage model for severe vasospasm. In both models, chronological changes of these three parameters were examined from day 1 until day 7. RESULTS In the single-hemorrhage model, mild vasospasm and a slight decrease of the cGMP level were noted on day 4, then both returned to the baseline levels on day 7. PKC activity was slightly enhanced throughout the study period. In the two-hemorrhage model, severe vasospasm and a significant decrease of the cGMP level were observed on day 5 and persisted until day 7. PKC activity was remarkably enhanced from day 5 until day 7. The differences between the two models with regard to the three parameters were statistically significant. CONCLUSIONS The decrease of cGMP level and the enhancement of PKC activity were obviously associated with the development of severe vasospasm. We conclude that subarachnoid hemorrhage disturbed the feedback control exerted by nitric oxide on PKC activation, leading to PKC-dependent vasospasm.

Protein kinase Cδ and α are involved in the development of vasospasm after subarachnoid hemorrhage

Abstract We have previously shown the enhanced activity of protein kinase C in the membrane fraction of the canine vasospastic artery after subarachnoid hemorrhage, which increased with progression of angiographic vasospasm. This study examined identification of protein kinase C isoforms in the canine basilar artery, and the changes in expression and/or translocation of each isoform during the development of vasospasm. Vasospasm was produced by using the “two-hemorrhage” canine model in the basilar artery, and angiographic progression of vasospasm was assessed consecutively. Two isoforms, protein kinase Cα and δ were identified in basilar arteries by Western blotting. Densitometric analysis showed that the expression of protein kinase Cδ in the membrane fraction was significantly increased in the earlier stage, and protein kinase Cα was increased later as vasospasm progressed. These results indicate that protein kinase Cδ and α isoforms may play a significant role in the development and maintenance of vasospasm.