Published papers

Purposes The intercavernous sinuses (ICSs) connect both sides of the cavernous sinus. Knowledge of the ICSs is useful when employing the endoscopic endonasal transsphenoidal approach. Although there were some studies concerning the anatomy of ICSs using cadavers, there is no well-recognized method of the radiological evaluation of the ICSs. Therefore, we evaluate the ICSs using computed tomography digital subtraction venography (CT-DSV) in the cases of unruptured aneurysm that had the normal sellae anatomy. Methods We retrospectively analyzed 97 cases of unruptured cerebral aneurysm that had normal parasellar and sellar anatomy except for the aneurysms. The analysis was performed using the multi-planar reconstruction images obtained by CT-DSV in these cases. Results The anterior ICS (AICS), inferior ICS (IICS) and posterior ICS (PICS) were detected in 51 cases (52.6%), 28 cases (28.9%) and 76 cases (78.4%) respectively. In the cases older than 51 years old, the AICS was detected significantly less often than in those younger than 50 years old. Conclusions The CT-DSV images directly reflected the blood flow. Most of the past research on the ICSs was obtained using cadavers, which could therefore not directly assess the normal human blood flow. The present study showed the usefulness of CT-DSV for evaluating the ICSs and to understand the normal anatomy of the ICSs.

Recently, petrous apex cholesterol granulomas (CGs) have been treated via the endoscopic endonasal transsphenoidal approach (EEA) using a silicone tube, to prevent drainage route occlusion. Occlusion of the drainage route has led to problems with recurrence. The aim of this report is to describe the use of a surgical technique to prevent drainage route occlusion. In surgical technique, the posterolateral wall of the sphenoid sinus was opened by EEA. After cyst debridement, a vascularized nasoseptal flap with a width of approximately 4 cm was inserted into the lumen with a silicone T-tube with a diameter of 7 mm. This technique was used in two patients: the first patient during the second operation after recurrence following occlusion of the drainage route, and the second patient during the first operation. Opening of the cyst wall was confirmed endoscopically in both patients 12–24 months after surgery, even after removal of the T-tube. In conclusion, the use of a pedicled nasoseptal flap with a silicone tube is useful to prevent CG recurrence, by paranasal cavitization of the cystic cavity.

Functional preservation is critical in glioma surgery, and the extent of resection influences survival outcome. Neoadjuvant chemotherapy is a promising option because of its potential to facilitate tumor shrinkage and maximum tumor resection. The object of this study was to assess the utility of the neoadjuvant strategy in a prospective series of gliomas with favorable molecular status. Twenty-six consecutive cases of diffuse gliomas of WHO grade II or III with either 1p19q codeletion or MGMT methylation were treated with upfront chemotherapy following maximal safe removal. In cases of incomplete initial surgery, second-look resection was intended after tumor volume decrease by chemotherapy. Among 22 evaluable cases, chemotherapy led to a median change in the sum of the product of perpendicular diameters of −35 %, and 14 out of the 22 cases (64 %) showed objective response. Second-look resection after tumor volume decrease was performed in 12 out of 19 cases of incomplete initial surgery (GTR/STR 9, removal of residual methionine PET uptake 3). The median progression-free survival among the 22 patients with grade II tumors was 57 months, with some cases showing durable progression-free survival after second-look resection. MIB-1 indices of the second-look resected tumors were lower than those of the initial tumors, and the methylation status of the MGMT gene was unchanged. Neoadjuvant chemotherapy based on molecular guidance often produces significant volume decrease of incompletely resected gliomas. Radical second-look resection is an optional advantage of upfront chemotherapy for chemosensitive gliomas compared with initial radiotherapy.

Steroid psychosis is a frequent complication of steroid treatment. Although perioperative steroid replacement therapy is generally administered in patients undergoing pituitary surgery, there are no previous reports concerning the development of steroid psychosis after perioperative steroid replacement therapy following pituitary surgery. We herein report a case of steroid psychosis induced by perioperative steroid replacement therapy for pituitary surgery. A 35-year-old man presented with a visual disturbance that had persisted for 1 year. A magnetic resonance imaging scan showed a large pituitary tumor, and a laboratory study revealed slight dysfunction of the hypothalamo-pituitary-adrenal axis. The patient was diagnosed with a non-functioning pituitary tumor and underwent tumor resection via the endoscopic endonasal approach. The initial dose of perioperative steroid replacement therapy was 200 mg of hydrocortisone administered immediately before the operation. The replacement dose was gradually tapered and discontinued over a 7-day period. On postoperative day 4, the patient exhibited an elated mood, grandiose delusions, anxiety, and agitation. We diagnosed these psychiatric symptoms as steroid psychosis induced by steroid replacement and we prescribed risperidone as a treatment. The symptoms gradually improved and did not recur. This case highlights the risk of steroid psychosis following treatment with perioperative steroid replacement therapy for pituitary adenoma and raises questions regarding the appropriateness of perioperative steroid replacement for pituitary adenoma.

OBJECT: Extended endoscopic transnasal surgeries for skull base lesions have recently been performed. Some expert surgeons have attempted to remove tumors such as chordomas, meningiomas, and pituitary adenomas in the clival region using the transnasal approach and have reported abducens nerve injury as a common complication. There have been many microsurgical anatomical studies of the abducens nerve, but none of these studies has described an anatomical landmark of the abducens nerve in the transnasal approach. In this study the authors used cadaver dissections to describe Grüber's ligament as the most reliable landmark of the abducens nerve in the transnasal transclival view.METHODS: The petroclival segment of the abducens nerve was dissected in the interdural space-which is also called Dorello's canal, the petroclival venous gulf, or the sphenopetroclival venous confluence-using the transnasal approach in 20 specimens obtained from 10 adult cadaveric heads.RESULTS: The petroclival segment of the abducens nerve clearly crossed and attached to Grüber's ligament in the interdural space, as noted in the transnasal view. The average length of the dural porus to the intersection on the abducens nerve was 5.2 ± 1.0 mm. The length of the posterior clinoid process (PCP) to the intersection on Grüber's ligament was 6.4 ± 2.6 mm. The average width of Grüber's ligament at the midsection was 1.6 ± 0.5 mm.CONCLUSIONS: Grüber's ligament is considered a useful landmark, and it is visible in most adults. Thus, surgeons can find the abducens nerve safely by visualizing inferolaterally along Grüber's ligament from the PCP.

To identify therapeutic molecular targets for glioma, we performed modified serological identification of antigens by recombinant complementary DNA (cDNA) expression cloning using sera from a mouse glioma model. Two clones, kinesin family member 23 (Kif23) and structural maintenance of chromosomes 4 (Smc4), were identified as antigens through immunological reaction with sera from mice harboring synergic GL261 mouse glioma and intratumoral inoculation with a mutant herpes simplex virus. The human Kif23 homolog KIF23 is a nuclear protein that localizes to the interzone of mitotic spindles, acting as a plus-end-directed motor enzyme that moves antiparallel microtubules in vitro. Expression analysis revealed a higher level of KIF23 expression in glioma tissues than in normal brain tissue. The introduction of small interfering RNA (siRNA) targeting KIF23 into two different glioma cell lines, U87MG and SF126, downregulated KIF23 expression, which significantly suppressed glioma cell proliferation in vitro. KIF23 siRNA-treated glioma cells exhibited larger cell bodies with two or more nuclei compared with control cells. In vivo analysis using mouse xenograft showed that KIF23 siRNA/DNA chimeratreated tumors were significantly smaller than tumors treated with control siRNA/DNA chimera. Taken together, our results indicate that downregulation of KIF23 decreases proliferation of glioma cells and that KIF23 may be a novel therapeutic target in malignant glioma. © 2011 Springer Science+Business Media, LLC.

To identify molecular therapeutic targets for glioma, we performed gene expression profiling by using a complementary DNA (cDNA) microarray method and identified the urokinase plasminogen activator receptor-associated protein (uPARAP/Endo180) as a gene expressed highly in glioma tissue compared with the normal brain tissue. The uPARAP is an endocytic receptor for collagen. In certain cell types, uPARAP occurs in a complex with the urokinase plasminogen activator receptor (uPAR) where it fulfills other functions in addition to collagenolysis. Quantitative PCR analysis using a cDNA panel revealed higher expression levels of uPARAP in glioma tissue compared with normal brain tissue. Western blot analysis revealed that the uPARAP protein was expressed in glioma samples and two glioma cell lines, KNS42 and KNS81, but not expressed in control tissue from the normal brain. Introduction of small interfering RNA-targeted uPARAP into the two different glioma cell lines, KNS42 and KNS81, resulted in downregulation of uPARAP expression, and it significantly suppressed glioma cell migration and invasion in vitro. Control glioma cells showed small cell bodies, whereas uPARAP siRNA-treated glioma cells exhibited large and flat morphology. Most of the polymeric actin in the control glioma cells was concentrated in the lamellipodia that are observed in mobile cells. In contrast, in the uPARAP siRNA-treated glioma cells, polymeric actin became organized in stress fibers and the lamellipodia disappeared, characteristic of immobile cells. Our present study suggests that uPARAP may be involved in glioma cell invasiveness through actin cytoskeletal rearrangement. downregulation of uPARAP may be a novel anti-invasion therapeutic strategy for malignant gliomas. © 2010 Springer Science+Business Media, LLC.

Background: HOX genes encode a family of homeodomain-containing transcription factors involved in the determination of cell fate and identity during embryonic development. They also behave as oncogenes in some malignancies.Results: In this study, we found high expression of the HOXD9 gene transcript in glioma cell lines and human glioma tissues by quantitative real-time PCR. Using immunohistochemistry, we observed HOXD9 protein expression in human brain tumor tissues, including astrocytomas and glioblastomas. To investigate the role of HOXD9 in gliomas, we silenced its expression in the glioma cell line U87 using HOXD9-specific siRNA, and observed decreased cell proliferation, cell cycle arrest, and induction of apoptosis. It was suggested that HOXD9 contributes to both cell proliferation and/or cell survival. The HOXD9 gene was highly expressed in a side population (SP) of SK-MG-1 cells that was previously identified as an enriched-cell fraction of glioma cancer stem-like cells. HOXD9 siRNA treatment of SK-MG-1 SP cells resulted in reduced cell proliferation. Finally, we cultured human glioma cancer stem cells (GCSCs) from patient specimens found with high expression of HOXD9 in GCSCs compared with normal astrocyte cells and neural stem/progenitor cells (NSPCs).Conclusions: Our results suggest that HOXD9 may be a novel marker of GCSCs and cell proliferation and/or survival factor in gliomas and glioma cancer stem-like cells, and a potential therapeutic target. © 2011 Tabuse et al; licensee BioMed Central Ltd.

Use of adequate adjuvant is necessary for induction of effective antitumor immune responses. To develop an effective adjuvant for cancer immunotherapy, we selected formalin-inactivated (f)-HSV as an adjuvant component, and analyzed the mechanisms underlying its adjuvant effects. First, we found that f-HSV can induce the tumor antigen-specific CTLs by enhancing antigen cross-presentation by dendritic cells (DCs), mainly through TLR2, but not TLR9. Next, f-HSV was also found to prevent the accumulation of myeloid-derived suppressor cells (MDSCs). We demonstrated that the expansion of MDSCs in the blood and spleen during tumor progression required B cells producing the inflammatory angiogenesis factors, vascular endothelial growth factor (VEGF)-A and neuropilin-1 (NRP-1), a co-receptor for VEGF receptor-2 (VEGFR-2). Interestingly, the transmembrane-type NRP-1 on B cells changed to soluble-type NRP-1 (sNRP-1) by f-HSV treatment. We further showed that the sNRP-1 and VEGF-A secreted from B cells by f-HSV treatment could abrogate the immunosuppressive ability of MDSCs. These results suggest that f-HSV can enhance antitumor immune responses as an adjuvant, not only through activation of DCs, but also inactivation of MDSCs via B cells. © 2010 UICC.

Progress in stem cell research has been associated with the discovery of the presence of cancer stem cells in a variety of malignant tumors, and because these cells are resistant to anticancer agents and radiotherapy, analysis of their properties has been rapidly pursued as an important target for the treatment of cancers, including malignant brain tumors. Brain cancer stem cells (BCSCs) have been isolated from brain tumor tissue and brain tumor cell lines by using neural stem cell culture methods. Analyzing the properties of BCSCs is extremely important to developing treatment methods that target BCSCs. Although no treatment method targeting BCSCs has yet been established, several methods have been proposed based on their cell-biological characteristics. This article describes therapeutic strategies that target drug-resistance molecules and stem-cell-associated molecules as well as immunotherapy targeted at BCSCs. © Masahiro Toda; Licensee Bentham Open.

To establish a simple and reliable test for assessing locomotor function in mice with brain injury, we developed a new method, the rotarod slip test, in which the number of slips of the paralytic hind limb from a rotarod is counted. Brain injuries of different severity were created in adult C57BL/6 mice, by inflicting 1-point, 2-point and 4-point cryo-injuries. These mice were subjected to the rotarod slip test, the accelerating rotarod test and the elevated body swing test (EBST). Histological analyses were performed to assess the severity of the brain damage. Significant and consistent correlations between test scores and severity were observed for the rotarod slip test and the EBST. Only the rotarod slip test detected the mild hindlimb paresis in the acute and sub-acute phase after injury. Our results suggest that the rotarod slip test is the most sensitive and reliable method for assessing locomotor function after brain damage in mice. © 2010 Elsevier Ltd. All rights reserved.

Because the temporal lobe extends deeply into the middle cranial fossa anteriorly, the procedure of the subtemporal approach should be modified so as to avoid damaging the brain and the cortical veins by compression with retractors. To minimize compression damage to the temporal lobe it is necessary to perform the craniotomy along the middle cranial fossa, and to remove the zygomatic arch for supratentorial lesions, and to remove the petrous pyramid for infratentorial lesions. An extradural approach is useful as a means of preventing damage to bridging veins including Labbe's vein, but because the superior petrosal sinus and the tentorium are transected in the procedure by the anterior transpetrosal approach, the drainage pathways of the superficial sylvian vein (especially the sphenobasal vein and the sphenopetrosal vein) should be checked preoperatively. In this article we outline the surgical anatomy of the middle cranial fossa required for the subtemporal approach and variations in the venous drainage of the superficial sylvian vein, and then we describe the treatment of petroclival lesions by the anterior transpetrosal approach.

Accumulating evidence suggests that in several types of brain tumors, including glioma, only a phenotypic subset of tumor cells called brain cancer stem cells (BCSCs) may be capable of initiating tumor growth. Recently, the isolation of side population (SP) cells using Hoechst dye has become a useful method for obtaining cancer stem cells in various tumors. In this study, we isolated cancer stem-like cells from human glioma cell lines using the SP technique. Flow cytometry analysis revealed that SK-MG-1, a human glioblastoma cell line, contained the largest number of SP cells among the five glioma cell lines that were analyzed. The SP cells had a self-renewal ability and were capable of forming spheres in a neurosphere culture medium containing EGF and FGF2. Spheres derived from the SP cells differentiated into three different lineage cells: neurons, astrocytes and oligodendrocytes. RT-PCR analysis revealed that the SP cells expressed a neural stem cell marker, Nestin. The SP cells generated tumors in the brains of NOD/SCID mice at 8 weeks after implantation, whereas the non-SP cells did not generate any tumors in the brain. These results indicate that SP cells isolated from SK-MG-1 possess the properties of cancer stem cells, including their self-renewal ability, multi-lineage differentiation, and tumorigenicity. Therefore, the SP cells from SK-MG-1 may be useful for analyzing BCSCs because of the ease with which they can be handled and their yield. © 2009 Elsevier Ireland Ltd. All rights reserved.

Cancer-induced immunotolerance mediated by inducible Treg (iTreg) is a major obstacle to cancer immunotherapy. In a basic study of immunotolerance, injection of an endogenous superantigen, i.e. the minor lymphocyte stimulatory (Mls)-1a, into specific TCR Vβ8.1-Tg mice enabled generation of anergic CD25- iTreg, the immunosuppressive function of which was maintained by IL-10 production via p38-MAPK activation. Interestingly, although p38-chemical inhibitor (p38-inhibitor) is capable of breaking CD25- iTreg-induced immunotolerance, the p38-inhibitor had hardly any immunotolerance breaking effect when CD25+ Treg were present, suggesting that depletion of CD25+ Treg is necessary for p38-inhibitor to be effective. Peptide OVA323-339 iv.-injection into its specific TCR-Tg (OT-II) mice also induced adaptive tolerance by iTreg. Peptide immunotherapy with p38-inhibitor after CD25+ Treg-depletion was performed in an OVA-expressing lymphoma E.G7-bearing tolerant model established by adoptive transfer of OT-II CD25- iTreg, which resulted in suppression of tumor growth. Similarly, the antitumor immunity induced by peptide immunotherapy in colon carcinoma CT26-bearingmice, in which the number of IL-10-secreting iTreg is increased, was augmented by treatment with p38-inhibitor after CD25 + Treg-depletion and resulted in inhibition of tumor progression. These results suggest that simultaneous inhibition of two distinct Treg-functions may be important to the success of cancer immunotherapy. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Malignant gliomas are the most aggressive human primary brain tumors and are currently incurable. Immunotherapies have the potential to target glioma and glioma stem cells (GSCs) that are resistant to conventional therapies. We previously identified SOX6 as a human glioma antigen and demonstrated that vaccination with SOX6 DNA induced cytotoxic T lymphocytes (CTLs) specific for glioma, thereby exerting therapeutic antitumor responses in glioma-bearing mice. In this study, we attempted to identify SOX6-derived peptides as specific targets for effective and safe T-cell-mediated immunotherapy targeting SOX6-positive glioma and GSCs. In vitro stimulation with human leukocyte antigen (HLA)-A*2402 (A24)-restricted peptides, RFENLGPQL (SOX6504) and PYYEEQARL (SOX6628) or the HLA-A*0201 (A2)-restricted peptide, ALFGDQDTV (SOX6447) was capable of inducing SOX6 peptide-specific CTLs in peripheral blood mononuclear cells derived from healthy donors and glioma patients. These CTLs were able to lyse a majority of glioma cell lines and a GSC line derived from human glioblastoma in an HLA Class I-restricted and an antigen-dependent manner. Furthermore, peptide vaccines of SOX6628, which was conserved in the murine SOX6 protein and expected to bind to major histocompatibility complex (MHC) H-2d, induced CTLs specific for SOX6628 in H-2d mice. Normal autologous cells from mice, in which SOX6-specific immune responses were generated, were not destroyed. These results suggest that these SOX6 peptides are potnetially immunogenic in HLA-A24 or -A2 positive glioma patients and should be considered as a promising strategy for safe and effective T-cell-based immunotherapy of patients with gliomas. © 2009 UICC.