Tomohisa Furuta

Proton magnetic resonance spectroscopy reflects cellular proliferative activity in astrocytomas.

Abstract We examined whether proton magnetic resonance spectroscopy (MRS) could provide accurate information on histological grade and cell proliferation in astrocytomas. We studied 23 patients with astrocytomas: five grade II, 10 grade III and eight with grade IV (glioblastoma multiforme). We performed proton MRS and determined the Ki-67 labeling index (LI), a tumour proliferation marker, in the same areas of the astrocytomas, and examined the statistical relationship between proton MRS and Ki-67 LI. The N-acetylaspartate (NAA)/creatine-phosphocreatine (Cr) and NAA/choline (Cho)-containing compound ratios were always significantly lower and the Cho/Cr ratios significantly higher than those for normal brain. The Cho/Cr ratio correlated positively and the NAA/Cho ratio inversely with Ki-67 LI. These findings suggest that the Cho signal in proton MRS reflects cellular proliferation. In Kaplan-Meier survival analysis, there was no significant difference between high (> 2.0, 14 cases) and low (< 2.0, 9 cases) Cho/cr ratio groups.

Malignant astrocytomas with homozygous CDKN2/p16 gene deletions have higher Ki-67 proliferation indices

p16 is involved in a cell-cycle regulatory cascade that includes cyclin-dependent kinase 4 (cdk4), cyclin D1 and pRb. Alterations of each of these components have been described in primary human glioblastoma multiforme (GBM) or GBM cell lines, and alterations of the individual components of this pathway appear inversely correlated with one another. While this suggests that disruption of any individual component has similar oncogenic effects, homozygous deletions of the CDKN2/p16 gene are the most common genetic alteration. We investigated the relationship between homozygous CDKN2/ p16 deletions and cellular proliferation in 50 primary astrocytomas (2 WHO grade I pilocytic astrocytoma, 15 grade II astrocytomas, 20 grade III anaplastic astrocytomas and 13 grade IV GBMs). Using a comparative multiplex PCR assay, homozygous deletions of the CDKN2/p16 gene were detected in 5 anaplastic astrocytomas (25%) and 6 GBMs (46%), but in none of the lower-grade tumors. Ki-67 immunohistochemistry was used to assess the number of proliferating cells in the same samples used for molecular genetic analysis. In both anaplastic astrocytomas and GBMs, Ki-67 proliferation indices were significantly higher in tumors with CDKN2/p16 deletions (20%) than in those without deletions (10%; p = 0.0001). These results suggest that homozygous CDKN2/p16 deletions in high-grade astrocytomas may have a more deleterious effect on cell cycle control than the other aberrations in the p16-cdk4-cyclin D1-pRb pathway, and may provide one explanation for why homozygous CDKN2/p16 deletions are more common genetic events in high-grade astrocytomas than RB mutations or CDK4 amplification.

Enhanced recovery of the nigrostriatal dopaminergic system in MPTP-treated mice following intrastriatal injection of basic fibroblast growth factor in relation to aging.

Studies have suggested that the restorative effects of adrenal medullary chromaffin cell grafts in animal models of Parkinsons disease may be related to trophic factors contained within the chromaffin cells. Basic fibroblast growth factor (bFGF) is present in chromaffin cells and has been shown to exert trophic effects on dopaminergic neurons in vitro. Basic FGF was stereotaxically injected into the striatum of young (2-month-old) and aging (12-month-old) C57BL/6 mice which had been treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) 1 week earlier. MPTP treatment reduced tyrosine hydroxylase (TH)-immunoreactive (IR) fibers in the striatum and striatal dopamine (DA) concentration in both the young and older mice 5 weeks later. Computerized image analysis of striatal DA fibers in young mice treated with bFGF showed significant recovery of DA fibers up to 600 microns from the injection site 5 weeks after MPTP administration. Striatal DA fibers in older mice treated with bFGF showed significant recovery only up to 300 microns from the injection site, and the degree of recovery was very limited compared with young mice. HPLC analysis of DA concentration revealed that striatal DA in young mice recovered significantly when treated with bFGF, but no significant recovery was observed in older mice. It is concluded that bFGF enhances the recovery of striatal DA systems from MPTP toxicity both in young and in older mice, but that such benefits are very limited in older mice.

In vivo efficacy and toxicity of 5-fluorocytosine/cytosine deaminase gene therapy for malignant gliomas mediated by adenovirus.

We evaluated the therapeutic efficacy and neurotoxicity of adenovirus-mediated transduction of the cytosine deaminase (CD) gene and 5-fluorocytosine (5-FC) for experimental malignant brain tumors. The 5-FC sensitivity in 9 L cells infected by an adenovirus vector expressing CD (AdexCACD) was increased 1700-fold compared with control cells. Rats bearing 9 L brain tumors were treated with an intratumoral injection of AdexCACD followed by intraperitoneal administration of 5-FC. The rats demonstrated remarkable inhibition of tumor growth by magnetic resonance imaging, and 7 of 10 rats survived for >90 days. To evaluate the potential side-effects of the 5-FC/CD gene therapy, rats were treated with an intracerebral injection of AdexCACD into the right basal ganglia and with 5-FC. The magnetic resonance imaging showed a highly enhanced area on the gadollinium-enhanced T1-weighted image at 18 days postinjection. Pathologically, this corresponded to an area of necrosis with surrounding apoptotic cells. In addition, there was demyelination and gliosis with enlargement of the lateral ventricles. These results suggest that the 5-FC/CD gene therapy may provide an anticancer effect for malignant brain tumors in humans, but also show that there are neurotoxic effects on normal brain tissue.

Neurinomas Presenting as Spontaneous Intratumoral Hemorrhage

Massive intratumoral or subarachnoid hemorrhage from neurinomas is very rare. The authors report on six patients, four men and two women, with neurinomas that presented as spontaneous intratumoral hemorrhage. The average age of the patients was 56.8 years (range, 31-74 years). Neurinomas originated from the acoustic nerve in four patients and from the trigeminal nerve in two. Four cases were accompanied by the sudden occurrence of clinical symptoms such as headache, double vision, and hemisensory or motor disturbance. The maximum diameter of the tumors ranged from 2.8 to 3.8 cm (average, 3.1 cm). Histological examinations showed massive hemorrhage and increased vascularity, with dilated, thin-walled vessels, in all cases. The size of the tumor and the increase in vascularity with dilated, thin-walled vessels within neurinomas are important pathogenetic factors of hemorrhage. When sudden onset of symptoms or rapid worsening of chronic symptoms occurs in neurinomas, intratumoral or subarachnoid hemorrhage should be considered as a possible cause, and magnetic resonance imaging can be an important tool in obtaining correct diagnosis.

The effect of a new immunosuppressive agent, FK-506, on xenogeneic neural transplantation in rodents

This study examines the effect of a novel immunosuppressive agent FK-506 (FK) on the survivability of embryonic (E14) rat ventral mesencephalic tissue after intracerebral grafting to the lateral ventricle of adult mice. The recipient mice were given FK in doses of 10 mg/kg or 1 mg/kg for 2 weeks postgrafting, at which time they were sacrificed and histologically processed except for one group of animals on the high dose (10 mg/kg). In this group most animals died from side effects of the drug during the following days. Only the mice receiving the high dose of FK displayed healthy grafts without signs of rejection.

Immunohistochemical localization of S-100 protein in human cerebral and cerebellar cortices.

S-100 protein, a highly acidic protein specific to the nervous system, is immunohistochemically localized exclusively in glial cells, but not in any type of neuron in human cerebral and cerebellar cortices.

Cerebral Gangliogliomas: Clinical Characteristics, CT and MRI

Summary Eight patients with ganglioglioma who received surgical treatment at our institute between January 1989 and January 1997 were reviewed to determine their clinical, CT and MRI characteristics. Tumours were located in the temporal lobe (four patients), trigone of the lateral ventricle (two patients), basal ganglia (one patient) and fronto-temporal lobe (one patient). On imaging, two types of tumours were seen, a solid mass in 5 patients (62.5%) and a cystic mass in three patients (37.5%). Six complete tumours (75%) and all of the solid components of the cystic tumours were enhanced by contrast medium. Seven tumours (88%) had no peripheral oedema. On CT, the tumours being studied appeared as iso-(62.5%) or low density (37.5%) intra-axial tumours. Four tumours (50%) contained calcification. On MRI, the tumours appeared as well-circumscribed, iso- (62.5%) or low intensity (37.5%) intra-axial tumours on T1 weighted images, and as high (75%) on T2 weighted images. Three underwent total resection, 2 subtotal resection and 3 partial resection. No patients had have any further treatment such as radiation therapy or chemotherapy. Postoperative sudies were conducted on all patients with an average follow-up period 56 months (range 4–147 months) after surgery. There was no evidence of recurrence of tumours or of growth of residual tumours. We observed gangliogliomas which were located in unusual regions such as the trigone in two of the patients. To our knowledge, our series is the first report to describe trigonal gangliogliomas. We conclude, therefore, that ganglioglioma should be included as a possibility in the differential diagnosis of intracranial masses, even when they are located in the trigone.

Accumulation of wild-type p53 in astrocytomas is associated with increased p21 expression

Abstract Approximately one quarter of human astrocytomas show immunohistochemical positivity for p53 protein but lack p53 gene mutations, which could reflect either an accumulation of wild-type p53 protein or an inadequate sensitivity of mutation detection. Since wild-type p53 up-regulates p21 expression, increased p21 expression in those astrocytomas with p53 accumulation in the absence of mutations would argue that the protein was wild type in these tumors. We therefore compared p21 expression with p53 gene and protein status in 48 primary human astrocytomas. Single-strand conformation polymorphism analysis and direct sequencing of the p53 gene showed mutations in 11 tumors (22.9%), while immunohistochemistry revealed positive staining in 19 cases (39.6%). Those tumors with p53 immunopositivity in the absence of p53 mutation had significantly increased p21 expression when compared to either mutant p53 or p53-immunonegative cases. Neither p53 nor p21 status correlated with proliferation indices, as assessed by Ki-67 immunohistochemistry. These results support the hypotheses that functionally wild-type p53 accumulates in some astrocytomas, and that alternative cell cycle checkpoints (such as the p16 pathway) may be more important than p21 in regulating proliferation in astrocytomas.

Spinal atypical teratoid/rhabdoid tumor in an infant.

Atypical teratoid/rhabdoid tumor of the central nervous system in infancy and childhood was established as an entity based on histological, immunohistochemical, and cytogenetic studies. We report the case of a 7-month-old girl who presented with progressive paraplegia and hypesthesia of her legs. Imaging studies revealed a spinal cord mass occupying the entire spinal canal below the T7 level. Through a T12-L3 laminectomy, the intramedullary tumor was partially debulked. Histologically, the tumor specimen had rhabdoid cells, and immunostaining showed vimentin and cytokeratin positivity. No abnormality of chromosome 22q was detected with the fluorescence in situ hybridization method.