Takuro Hayashi

The Cdk inhibitor flavopiridol enhances temozolomide-induced cytotoxicity in human glioma cells

The recent progress in chemotherapy for malignant gliomas is attributable to the introduction of the DNA-methylating agent temozolomide (TMZ); however, drug resistance remains a major issue. Previous studies have shown that TMZ induces prolonged arrest of human glioma cells in the G2/M phase of the cell cycle followed by a senescence-like phenomenon or mitotic catastrophe. These findings suggest that the G2 checkpoint is linked to DNA repair mechanisms. We investigated the effect of a cyclin-dependent kinase (Cdk) inhibitor flavopiridol (FP) that inhibits the action of Cdc2, a key protein in the G2 checkpoint pathway, on TMZ-treated glioma cells. Colony formation efficiency revealed that FP potentiated the cytotoxicity of TMZ in glioma cells in a p53-independent manner. This effect was clearly associated with the suppression of key proteins at the G2-M transition, accumulation of the cells exclusively at the G2 phase, and increase in a double-stranded DNA break marker (seen on performing immunoblotting). TMZ-resistant clones showed activation of the G2 checkpoint in response to TMZ, while FP treatment resensitized these clones to TMZ. FP also enhanced the cytotoxicity of TMZ in U87MG-AktER cells. Moreover, administration of TMZ and/or FP to nude mice with xenografted U87MG cells revealed that FP sensitized xenografted U87MG cells to TMZ in these mice. Our findings suggest that TMZ resistance could be promoted by enhanced DNA repair activity in the G2-M transition and that a Cdk inhibitor could suppress this activity, leading to potentiation of TMZ action on glioma cells.

Clinical characteristics and risk factors of chronic subdural haematoma associated with clipping of unruptured cerebral aneurysms

Chronic subdural haematoma (CSDH) is an uncommon but potentially serious complication of clipping unruptured cerebral aneurysms. We conducted a study to identify the patients who are at risk of developing postoperative CSDH. The data from 713 consecutive patients who underwent clipping of unruptured anterior circulation aneurysms were reviewed, and risk factors correlated with CSDH were identified by multivariate regression analysis of demographic variables. Fifteen patients (2.1%) developed CSDH after the surgery. Advanced age (odds ratio [OR] 1.151, 95% confidence interval [CI] 1.051-1.261) and male gender (OR 3.167, 95% CI 1.028-9.751) were correlated with CSDH. Subsequently, all 713 patients were quadrichotomized on the basis of gender and age, with 70 years as the cut-off value for age. The frequency of CSDH in men <70 years of age was 1.3% and that in men ≥70 years of age was 15.1%, with risk of CSDH was significantly higher in the older men (OR 13.39; 95% CI: 3.42-52.44). The frequency of CSDH in women <70 years of age was 0.6% and that in women ≥70 years of age was 3.7%. As in men, the risk of CSDH was significantly higher in the older women (OR 6.69, 95% CI 1.10-40.73). The interval between the aneurysm clipping and CSDH development was 0.5-6 months, suggesting that clinical observation should be continued up to 6 months after surgery. Although prognosis for patients with a postoperative CSDH complication is generally favourable, the risk of CSDH should be taken into account when considering elective clipping of unruptured aneurysms in patients ≥70 years of age.

Subgrouping of gliomas on the basis of genetic profiles

Management of gliomas depends on histological diagnosis; there are, however, limitations to the systems presently used. Tumors in the same entity can have different clinical courses, especially when they are diagnosed as WHO grade II–III. Previous studies revealed that genetic subgrouping of gliomas provides useful information that could help establishment of treatment procedures on the basis of the genetic background of the tumors. Recently, the authors analyzed the chromosomal copy number aberrations (CNAs) of adult supratentorial gliomas by comparative genomic hybridization using microdissected tissue sections. The tumors were classified into subgroups according to chromosomal CNAs. WHO grade II–III gliomas contained a variety of genetic subgroups that correlated well with the clinical course. Of these, long progression-free survival was observed for tumors with +7q and those with −1p/19q, low-grade tumors of 2 major lineages, and, in our preliminary data, both were closely correlated with mutation of IDH1. Furthermore, in contrast with +7q tumors, the great majority of +7 or +7/−10q groups had wildtype IDH1. Genetic studies suggest that cytogenetic characterization may provide an additional classification system for gliomas, and new criteria could help to establish rational and objective means for analysis of treatment procedures.

Decompressive Hemicraniectomy for Malignant Hemispheric Stroke in the Elderly: Comparison of Outcomes between Individuals 61-70 and .70 Years of Age

BACKGROUND Malignant hemispheric infarction is a life-threatening condition with a high mortality rate. Decompressive hemicraniectomy (DHC) is frequently a life-saving procedure that has shown the highest grade of evidence for patients 18 to 60 years of age. However, the efficacy of DHC in patients>60 years of age has rarely been investigated. METHODS A retrospective study was conducted in a single academic institution. Surrogates of patients with clinical signs of impending brain herniation despite standard medical therapy were offered the option of DHC regardless of age or the side of the lesion. The clinical data from 18 patients>60 years of age who underwent DHC for malignant hemispheric infarction in our institution were analyzed. Patients were classified into the following 2 groups: 61-70 and >70 years of age, and their demographics and surgical outcomes were compared. The variables compared included the male:female ratio, side of the lesion, type of stroke, site of vascular occlusion, use of thrombolytic therapy, National Institutes of Health Stroke Scale score, stroke onset-to-DHC interval, duration of hospital stay, infectious complications, and 90-day mortality rate. RESULTS There were no significant intergroup differences in any of the demographic variables evaluated. However, the 30-day mortality rate was significantly higher in the group that was >70 years of age (0% v 60%; P=.01) than in the group that was 61 to 70 years of age. CONCLUSIONS We suggest that the efficacy of DHC in malignant hemispheric stroke patients between 61 and 70 years of age be further investigated in future randomized trials. By contrast, it appears unlikely that patients>70 years of age would benefit from DHC.

Neuroepithelial cyst of the fourth ventricle.

PurposeNeuroepithelial cyst is considered an unusual differential diagnosis for cysts in the posterior fossa. Here, we present a paediatric case with such a pathology and review the pertinent literature.MethodsA 12-year old girl with headache, vertigo and disturbed gait was diagnosed with a cystic lesion in the fourth ventricle after brain MRI study. She was operated with the pre-operative diagnosis of arachnoid cyst.ResultsA transparent, colourless cyst was observed intra-operatively. As frozen sections were consistent with endodermal cyst, total removal of the cyst was attempted. Definite histopathological studies and immunohistochemistry stains were in favour of neuroepithelial cyst. No regrowth of the cyst or recurrence of the symptoms was observed in her 2-year follow-up.ConclusionsAs neuroepithelial cyst is rarely encountered in the posterior fossa, the clinical, radiological and pathological characteristics of our case along with similar cases in the literature were reviewed and discussed.

World Health Organization grade II-III astrocytomas consist of genetically distinct tumor lineages.

Recent investigations revealed genetic analysis provides important information in management of gliomas, and we previously reported grade II–III gliomas could be classified into clinically relevant subgroups based on the DNA copy number aberrations (CNAs). To develop more precise genetic subgrouping, we investigated the correlation between CNAs and mutational status of the gene encoding isocitrate dehydrogenase (IDH) of those tumors. We analyzed the IDH status and CNAs of 174 adult supratentorial gliomas of astrocytic or oligodendroglial origin by PCR‐based direct sequencing and comparative genomic hybridization, respectively. We analyzed the relationship between genetic subclassification and clinical features. We found the most frequent aberrations in IDH mutant tumors were the combined whole arm‐loss of 1p and 19q (1p/19q codeletion) followed by gain on chromosome arm 7q (+7q). The gain of whole chromosome 7 (+7) and loss of 10q (−10q) were detected in IDH wild‐type tumors. Kaplan–Meier estimates for progression‐free survival showed that the tumors with mutant IDH, −1p/19q, or +7q (in the absence of +7p) survived longer than tumors with wild‐type IDH, +7, or −10q. As tumors with +7 (IDH wild‐type) showed a more aggressive clinical nature, they are probably not a subtype that developed from the slowly progressive tumors with +7q (IDH mutant). Thus, tumors with a gain on chromosome 7 (mostly astrocytic) comprise multiple lineages, and such differences in their biological nature should be taken into consideration during their clinical management.

PCR-Based Simple Subgrouping Is Validated for Classification of Gliomas and Defines Negative Prognostic Copy Number Aberrations in IDH Mutant Gliomas

Genetic subgrouping of gliomas has been emphasized recently, particularly after the finding of isocitrate dehydrogenase 1 (IDH1) mutations. In a previous study, we investigated whole-chromosome copy number aberrations (CNAs) of gliomas and have described genetic subgrouping based on CNAs and IDH1 mutations. Subsequently, we classified gliomas using simple polymerase chain reaction (PCR)-based methods to improve the availability of genetic subgrouping. We selected IDH1/2 and TP53 as markers and analyzed 237 adult supratentorial gliomas using Sanger sequencing. Using these markers, we classified gliomas into three subgroups that were strongly associated with patient prognoses. These included IDH mutant gliomas without TP53 mutations, IDH mutant gliomas with TP53 mutations, and IDH wild-type gliomas. IDH mutant gliomas without TP53 mutations, which mostly corresponded to gliomas carrying 1p19q co-deletions, showed lower recurrence rates than the other 2 groups. In the other high-recurrence groups, the median progression-free survival (PFS) and overall survival (OS) of patients with IDH mutant gliomas with TP53 mutations were significantly longer than those of patients with IDH wild-type gliomas. Notably, most IDH mutant gliomas with TP53 mutations had at least one of the CNAs +7q, +8q, −9p, and −11p. Moreover, IDH mutant gliomas with at least one of these CNAs had a significantly worse prognosis than did other IDH mutant gliomas. PCR-based mutation analyses of IDH and TP53 were sufficient for simple genetic diagnosis of glioma that were strongly associated with prognosis of patients and enabled us to detect negative CNAs in IDH mutant gliomas.

Radiological features of supratentorial gliomas are associated with their genetic aberrations

Gliomas are the most common primary neoplasms of the central nervous system [1]. Histopathological examination of surgically resected tissue is essential for the diagnosis of gliomas, and it forms the basis on which decisions regarding the use of adjuvant therapies are taken. This methodology has several potential difficulties, however. These include the fact that even pathologically identical tumors may have a different prognosis, that occasionally different areas of the same tumor tissue can have different histological characteristics [2], and that there is no entirely objective way of interpreting cellularity, anaplasia, or even cell type. To address these problems, many studies have tried to distinguish tumors on the basis of genetic and protein markers with the aim of standardizing decisions regarding therapeutic strategy based on the tumor subtypes they defined [3, 4]. Of particular note are the allelic losses of chromosomes 1p and 19q (−1p/19q), which have been reported as being positive predictors of chemotherapeutic response for anaplastic oligodendroglial tumors [5, 6]. Moreover, after Parsons et al. demonstrated that some gliomas carry a mutation in the IDH1 gene, genetic investigations have become increasingly important in the study of glioma biology [7]. However, although genetic analysis does provide important information, it requires an invasive surgical procedure. In addition to information provided by genetic analysis, some recent studies have suggested an association between radiological features and tumor type. To better understand the association between the radiological and genetic features of gliomas and to establish prognostic radiological criteria, we designed a study to test whether certain radiological features could be used to predict genetic aberrations in World Health Organization (WHO) grade II–III astrocytic and oligodendroglial tumors.

Surgical navigation-assisted endoscopic biopsy is feasible for safe and reliable diagnosis of unresectable solid brain tumors

Stereotactic biopsy has been validated for tissue sampling of deep-seated lesions that cannot be easily resected via open craniotomy. However, some inherent problems including the inability to directly observe the lesion and difficulty in confirming hemostasis limit its usefulness. To overcome these issues, we used the endoscope in brain tumor biopsy, for not only intraventricular tumors but also intraparenchymal tumors. The rigid scope was used in association with a surgical navigation system for intraparenchymal lesions via a transcortical route. There were no useful anatomical landmarks when the trajectory to the lesions was decided; therefore, surgical navigation system was required for the transcortical procedures. The endoscopic procedure described here was attempted in 21 cases of intraparenchymal lesions between January 2007 and February 2012. A definitive diagnosis was obtained in all cases, and genetic analysis was performed when required. Serious postsurgical hemorrhage or neurological deficits were not observed in any cases. Endoscopic surgery provides a clear view of the target and makes it easier to differentiate tumor tissue from normal brain tissue. Moreover, the endoscope helped to confirm hemostasis during the procedure. Thus, endoscopic biopsy has the potential to contribute toward safe and reliable diagnosis of brain tumors.

Prediction of genetic subgroups in adult supra tentorial gliomas by pre- and intraoperative parameters

Recent progress in neuro-oncology has validated the significance of genetic diagnosis in gliomas. We previously investigated IDH1/2 and TP53 mutations via Sanger sequencing for adult supratentorial gliomas and reported that PCR-based sequence analysis classified gliomas into three genetic subgroups that have a strong association with patient prognosis: IDH mutant gliomas without TP53 mutations, IDH and TP53 mutant gliomas, and IDH wild-type gliomas. Furthermore, this analysis had a strong association with patient prognosis. To predict genetic subgroups prior to initial surgery, we retrospectively investigated preoperative radiological data using CT and MRI, including MR spectroscopy (MRS), and evaluated positive 5-aminolevulinic acid (5-ALA) fluorescence as an intraoperative factor. We subsequently compared these factors to differentiate each genetic subgroup. Multiple factors such as age at diagnosis, tumor location, gadolinium enhancement, 5-ALA fluorescence, and several tumor metabolites according to MRS, such as myo-inositol (myo-inositol/total choline) or lipid20, were statistically significant factors for differentiating IDH mutant and wild-type, suggesting that these two subtypes have totally distinct characteristics. In contrast, only calcification, laterality, and lipid13 (lipid13/total Choline) were statistically significant parameters for differentiating TP53 wild-type and mutant in IDH mutant gliomas. In this study, we detected several pre- and intraoperative factors that enabled us to predict genetic subgroups for adult supratentorial gliomas and clarified that lipid13 quantified by MRS is the key tumor metabolite that differentiates TP53 wild-type and mutant in IDH mutant gliomas. These results suggested that each genetic subtype in gliomas selects the distinct lipid synthesis pathways in the process of tumorigenesis.