Yasuhiko Hayashi

Induction of various blood-brain barrier properties in non-neural endothelial cells by close apposition to co-cultured astrocytes

Vascular endothelial cells (EC) exhibit organ‐to‐organ heterogeneity in their functions and morphologies. In particular, brain capillary EC have unique characteristics exemplified by the blood‐brain barrier (BBB). The formation and the maintenance of BBB have been ascribed to EC responses to inductive signal(s) or factor(s) from astrocytes that encircle microvessels in the central nervous system. These EC responses were demonstrated in numerous in vivo studies, exemplified by those of Janzer and Raff (Nature 325:253, 1987) and Tout et al. (Neuroscience 55:291, 1993) showing that transplanted astrocytes induced BBB properties in non‐neural vascular EC. In this study, we constructed a heterologous co‐culture system, in which rat fetal brain astrocytes were cultivated on one surface of a porous membrane and human umbilical vein EC on the opposite surface. Electron microscopic examination revealed that astrocytes passed their endfeet through the pores, making contact with EC. In this system, γ‐glutamyltranspeptidase (γ‐GTP) activity in EC was found to be significantly increased by contacting astrocytes in a density‐and time‐dependent manner, but not when the astrocyte feeder layer was apart from EC or replaced by COS cells; astrocyte‐derived extracellular matrix partially activated γ‐GTP. mRNAs for some of the representative BBB markers, including transferrin receptor, P‐glycoprotein, brain‐type glucose transporter(GLUT‐1), and γ‐GTP were also demonstrated by reverse transcription‐polymerase chain reaction to be upregulated in EC co‐cultured with astrocytes. Astrocyte inductions of close membrane apposition resembling a zonula occludens and of an increase in the content of mitochondria in EC were also noted in electron micrographs. Furthermore, an increased barrier activity against inulin was conferred on EC when they were lined with astrocytes. The results obtained with this heterologous co‐culture system thus indicate that through contact with their feet, astrocytes are capable of transdifferentiating non‐neural EC into the brain type, endowing them with the BBB properties. Glia 19:13–26, 1997

Prediction of high-grade meningioma by preoperative MRI assessment

High-grade (World Health Organization grades II and III) meningiomas grow aggressively and recur frequently, resulting in a poor prognosis. Assessment of tumor malignancy before treatment initiation is important. We attempted to determine predictive factors for high-grade meningioma on magnetic resonance (MR) imaging before surgery. We reviewed 65 meningiomas (39 cases, benign; 26 cases, high-grade) and assessed four factors: (1) tumor–brain interface (TBI) on T1-weighted imaging (T1WI), (2) capsular enhancement (CapE), i.e., the layer of the tumor–brain interface on gadolinium-enhanced T1WI (T1Gd), (3) heterogeneity on T1Gd, and (4) tumoral margin on T1Gd. All four factors were useful in distinguishing high-grade from benign meningiomas, according to univariate analysis. On multivariate regression analysis, unclear TBI and heterogeneous enhancement were independent predictive factors for high-grade meningioma. In meningiomas with an unclear TBI and heterogeneous enhancement, the probability of high-grade meningioma was 98%. Our data suggest that this combination of factors obtained from conventional sequences on MR imaging may be useful to predict high-grade meningioma.

Sphingosine-1-phosphate receptor type 1 regulates glioma cell proliferation and correlates with patient survival

Sphingosine‐1‐phosphate (S1P) is a bioactive lipid that signals through a family of G protein‐coupled receptors consisting of 5 members termed S1P1–5, and it regulates cellular proliferation, migration and survival. We investigated the expression and role of S1P receptors in glioma. Human glioma expressed S1P1, S1P2, S1P3, and S1P5 by quantitative real‐time PCR analysis. Expression of the S1P1 was significantly lower in glioblastoma than in the normal brain (p < 0.01) and diffuse astrocytoma (p < 0.05). Immunoblotting showed that normal brain expressed more S1P1 protein than did glioblastoma. Immunohistochemistry showed that S1P1 was localized predominantly in the astrocytes in the normal brain, but no staining was observed in glioblastoma. Downregulation of S1P1 expression correlated with poor survival of patients with glioblastoma (p < 0.05). S1P1 small interfering RNA promoted cell proliferation in high‐expressor glioma cell lines (T98G, G112). Cell proliferation was promoted by the pertussis toxin, which deactivates Gi/o type of G proteins; the S1P1 is exclusively coupled to these proteins. Forced expression of the S1P1 in low‐expressor cell lines (U87, U251) resulted in decreased cell growth and led to suppressed tumor growth in transplanted gliomas in vivo. Furthermore, we found a significant association between the S1P1 expression and early growth response‐1, a transcriptional factor that exhibits tumor suppression in glioblastoma cells (p < 0.05). These data indicate that the downregulation of S1P1 expression enhances the malignancy of glioblastoma by increasing cell proliferation and correlates with the shorter survival of patients with glioblastoma.

A reevaluation of the primary diagnosis of hemangiopericytoma and the clinical importance of differential diagnosis from solitary fibrous tumor of the central nervous system.

OBJECTIVES Hemangiopericytomas (HPCs) are rare neoplasms with relatively high rates of recurrence and extracranial metastasis. Though the differential diagnoses from angiomatous meningiomas and from solitary fibrous tumors (SFTs) are both important, the latter diagnosis is somewhat more important in light of the benign prognosis of SFTs and the difficulties in distinguishing SFTs from HPCs. Newly developed immunohistochemical methods reveal differences in the specific immunohistochemical features of HPCs and SFTs. To elucidate whether SFTs have been misdiagnosed as HPCs in the past, our group used recent immunohistochemical methods to re-evaluate tissues that had been originally diagnosed as HPCs. We also compared the clinical features of these cases. PATIENTS AND METHODS Thirteen sequential cases of HPC diagnosed in Kanazawa University Hospital and Kumamoto University Hospital between 1970 and 2006 were retrospectively analyzed by immunohistochemical staining for CD34, Bcl-2, epithelial membrane antigen (EMA), vimentin, and S100 protein, and by measurement of the MIB-1 labeling index (LI). The cases were then re-evaluated and newly diagnosed based on the results of the immunohistochemical stainings. The clinical course of each case was also evaluated. RESULTS Four of the 13 cases were newly diagnosed as SFTs and eight were reconfirmed as HPCs, based on the immunohistochemical studies for CD34, Bcl-2, and reticulin staining. One case was newly diagnosed as meningioma on the basis of a strong EMA positivity. The MIB-1 LI was less than 1% in 12 of the cases. In two cases, one case of HPC and the other of meningioma, the MIB-1 LI was relatively high, 8% and 4% respectively. All eight of the HPCs recurred, and 5 of the HPC patients died of the disease. Only one case of the SFTs recurred. CONCLUSION Our study suggests that a relatively high percentage of the tumors diagnosed as HPCs in the past may have in fact been intracranial SFTs. Immunohistochemical examinations of CD34, Bcl-2, and reticulin stains are keys for the differential diagnosis. Given that SFTs have a considerably better prognosis than HPCs, it is important to carry out meticulous immunohistochemical examinations for the primary diagnosis.

Retro-odontoid pseudotumor without atlantoaxial subluxation

A retro-odontoid pseudotumor (ROP) is commonly associated with atlantoaxial subluxation (AAS). Here, we report a patient with ROP but without AAS. The patient was a 72-year-old man who did not have a history of rheumatoid arthritis or trauma to the head and neck. The patient was admitted to our hospital with gait disturbance, progressive motor weakness in both upper extremities and sensory disturbance in all four extremities. MRI showed a retro-odontoid mass with severe compression of the cervical spinal cord. A CT scan showed spondylotic changes in C5, C6, and C7 and bilateral facet fusion between C3 and C4. Dynamic radiography showed no evidence of AAS; there was loss of mobility at C2-C7 and excessive mobility at C1. Intraoperative pathological examination revealed that the lesion was a pseudotumor; therefore, posterior C1-C2 fixation was performed. MRI performed 6 months after the operation revealed that the pseudotumor was markedly reduced. To the best of our knowledge, patients with ROP without AAS are uncommon.

Relationship between macular ganglion cell complex parameters and visual field parameters after tumor resection in chiasmal compression

PurposeTo evaluate the relationship between macular ganglion cell complex (GCC) parameters and visual field (VF) parameters in chiasmal compression and the potential for GCC parameters in order to predict the short-term post-surgical VF.MethodsTwenty-three eyes of 12 patients with chiasmal compression and 33 control eyes were studied. All patients underwent transsphenoidal tumor resection. Before surgery a 3D scan of the macula was taken using spectral-domain optical coherence tomography. All patients underwent Humphrey 24-2 VF testing after surgery. Spearman’s rank correlation coefficients were used to evaluate the relationship between the GCC parameters and VF parameters [mean deviation (MD), pattern standard deviation]. Coefficients of determination (R2) were calculated using linear regression.ResultsAverage thickness in the patients was significantly thinner than that of controls. Average thickness, global loss volume and focal loss volume (FLV) significantly correlated with the MD. We observed the greatest R2 between FLV and MD.ConclusionsExamining the macular GCC was useful for evaluating structural damage in patients with chiasmal compression. Preoperative GCC parameters, especially FLV, may be useful in predicting visual function following surgical decompression of chiasmal compression.

Force detecting gripper and flexible micro manipulator for neurosurgery

In order to realize a less invasive robotic neurosurgery for the deeply seated tumor, a force detecting gripper with a flexible micro manipulator has been developed. Gripping force applied on the gripper is detected by strain gages fit on the gripper clip. Signal is conducted to the amplifier by the cables through the inner pipe of the manipulator. In order to approach to the deeply seated tumor through a narrow hole, a micro manipulator which can flex at the end part to face the gripper for the target and can rotate the closing direction of the gripper at the end of the manipulator has been developed. Some operation test showed that the developed manipulator can approach flexibly to the target, and the taking out force of a target on the soft material was detected clearly.

Radiation-induced cerebellar high-grade glioma accompanied by meningioma and cavernoma 29 years after the treatment of medulloblastoma: a case report

Here, we report the case of a patient with cerebellar high-grade glioma that developed after the patient underwent treatment for medulloblastoma. A 34-year-old man visited our hospital with complaints of dizziness and truncal ataxia. Magnetic resonance image showed a cerebellar tumor with multiple cavernomas and two lesions that were suspected to be meningiomas. The cerebellar tumor was surgically removed. According to pathological examination, the tumor was a high-grade glioma that was positive for methylated O-6-methylguanine-DNA methyltransferase promoter. In the past, he had received radiotherapy at the age of 5, after which he was operated for desmoplastic medulloblastoma in his right cerebellar hemisphere. Seven years after the initial therapy, cavernoma-induced intracerebral hemorrhage of the right temporal lobe was noted. To our knowledge, this is the first case of radiation-induced double intracranial tumors accompanied by symptomatic cavernoma.

Gonadotropin-releasing hormone (GnRH) and its receptor in human meningiomas

OBJECTIVE Meningiomas are the most common neoplasms of the central nervous system and are more frequent in women than in men. Many studies have been conducted to determine whether the progesterone receptor (PR) and estrogen receptor (ER) are present or absent in meningiomas. No previous studies, however, have investigated the status (presence or absence) of gonadotropin-releasing hormone (GnRH) and its receptor (GnRH-R), two major factors related to PR and ER, in meningiomas. This study aims to determine the status of GnRH and GnRH-R and to elucidate the correlations of GnRH and GnRH-R with PR, ER, and clinical features in meningiomas. METHODS Eighty-two specimens of human meningiomas were obtained for immunohistochemical analysis with anti-GnRH, anti-GnRH-R, anti-PR, anti-ER, and anti-Ki-67 (MIB-1) antibodies, and for RT-PCR analysis of the mRNA expressions of GnRH and GnRH-R. Correlations of GnRH and GnRH-R with PR, ER, Ki-67, and clinical features such as age, sex, tumor grade, and tumor histology were assessed. RESULTS Seventy-eight (95.1%) of the 82 meningiomas reacted positively in the cytoplasm for the GnRH-R. Forty-nine (59.8%) of the 82 cases reacted positively in the cytoplasm for the GnRH. The positive immunoreactivity for GnRH-R and GnRH was confirmed by the RT-PCR analyses of mRNA. Forty-seven (96%) of the 49 cases with positive immunoreactivity for GnRH-R also had positive immunoreactivity for GnRH. PR expression was higher in the tumors positive for GnRH-R (p=0.002), and a significantly higher proportion of tumors from male patients exhibited positive immunoreactivity for GnRH (p=0.02). No significant correlations were found between the status of GnRH-R or GnRH with other clinicopathological features. CONCLUSION Over half of meningiomas may be regulated by GnRH-GnRH-R expression in an autocrine fashion. This unique expression profile of GnRH and GnRH-R may open the way to the development of GnRH analogs as a treatment tool in the future.

Pure Lymphocytic Infundibuloneurohypophysitis Caused by the Rupture of Rathke's Cleft Cyst: Report of 2 Cases and Review of the Literature.

The major symptoms that are caused by Rathkes cleft cysts (RCCs) are visual disturbances, headaches, and endocrine insufficiencies. Among these symptoms, the endocrine insufficiencies are thought to result from the spreading of inflammation that is induced by the cyst contents onto the pituitary gland or the compression of the gland and the pituitary stalk by RCCs. Here, we present 2 rare cases with lymphocytic infundibulohypophysitis with the sudden onset of headaches and subsequent diabetes insipidus (DI). Magnetic resonance imaging revealed remarkable swelling of the pituitary gland with a small mass that was located between the anterior and the posterior lobe of the pituitary gland. Transsphenoidal surgery was performed to remove the mass, and pathological examinations of the cyst wall demonstrated that the epithelial tissue of the RCC and the posterior lobe were affected by massive lymphocytic infiltration. The clinical courses and pathological results of these patients strongly suggested that the rupture of the RCC onto the posterior lobe caused the lymphocytic hypophysitis. Postoperatively, the DI could be controlled with a smaller amount of anti-diuretic hormone replacement compared to that required preoperatively.