Akio Yasunaga

Nuclear Factor Kappa B Dependent Induction of Gamma Glutamylcysteine Synthetase by Ionizing Radiation in T98G Human Glioblastoma Cells

Glioblastoma is one of the most malignant of all neoplasms, and often shows resistance to chemotherapy and radiation therapy. Ionizing radiation activates transcriptional factors, such as nuclear factor kappa-B (NF-kappa B). Previously we found that glutathione (GSH) synthesis is induced by cytokines mediated by NF-kappa B (Urata et al. J. Biol. Chem., 1996). Here, we present direct evidence that NF-kappa B activated by ionizing radiation induces the expression of gamma-glutamylcysteine synthetase (gamma-GCS), the rate limiting enzyme of GSH synthesis, using T98G human glioblastoma cells. T98G cells have approximately 14-times the level of intracellular GSH of NB9 cells, radiation-sensitive neuroblastoma cells. In T98G cells, 30-Gy of ionizing radiation was required for the activation of NF-kappa B on an electrophoretic mobility shift assay and the induction of gamma-GCS mRNA on Northern blots and a nuclear run-on assay. However, when T98G cells were treated with buthionine sulfoximine, 3-Gy of ionizing radiation stimulated the DNA-binding activity of NF-kappa B and the expression of gamma-GCS. We constructed chimeric genes containing various regions of gamma-GCS promoter gene and the coding region for Luciferase. T98G cells transiently transfected with a plasmid containing the gamma-GCS promoter-luciferase construct showed increased luciferase activity when treated with ionizing radiation. The luciferase activity stimulated by ionizing radiation was found in the gamma-GCS promoter containing the NF-kappa B binding site, whereas not in that containing its mutated site. These results suggest that GSH synthesis is upregulated by ionizing radiation mediated by NF-kappa B and a high concentration of GSH in T98G cells causes downregulation of the NF-kappa B-DNA binding activity in response to ionizing radiation. The irresponsiveness of the intracellular signal transduction cascade to irradiation may be a factor in the resistance of T98G cells to radiation therapy.

Immunohistochemical analysis of metallothionein in astrocytic tumors in relation to tumor grade, proliferative potential, and survival

Metallothionein (MT) is the name for a family of predominantly intracellular protein thiol compounds involved in anticancer drug resistance. For certain tumors, MT is related to grade of tumor malignancy and prognosis. The authors evaluated the expression of MT in 114 astrocytic tumors in relation to the proliferative potential of tumors and the survival of patients.

EXPRESSION OF THE SMALL HEAT SHOCK PROTEIN (HSP) 27 IN HUMAN ASTROCYTOMAS CORRELATES WITH HISTOLOGIC GRADES AND TUMOR GROWTH FRACTIONS

Summary1. Cellular expression and distribution of the stress response small heat shock protein 27 (hsp27) in 39 high-grade astrocytomas (27 glioblastoma multiformes, 12 anaplastic astrocytomas) and in 27 low-grade astrocytomas (grade I–II) were analyzed immunohistochemically.2. The correlation between hsp27 expression and tumor growth fractions of the astrocytomas was examined following Ki-67 immunostaining.3. The hsp27 staining was cell cytoplasmic. The hsp27 immunopositive rate was significantly higher in high-grade astrocytomas; the rates were 74% for glioblastomas, 58% for anaplastic astrocytomas, and 37% for low-grade astrocytomas. The small and large tumor cells, especially in glioblastomas, multinucleated tumor giant cells, tumor cells in the pseudopalisading and necrotic areas, cells of the microvascular endothelial proliferations, and tumor vascular smooth muscles were usually hsp27 positive. The mean percentage of hsp27-positive cells was significantly higher in the glioblastomas alone and in the combined high-grade astrocytomas, compared to the low-grade, and in recurrent rather than in primary high-grade astrocytomas.4. The high-grade astrocytomas had a highly statistical significant Ki-67 labeling index. The Ki-67 labeling indices were significantly higher in the hsp27-positive than the hsp27-negative astrocytomas, irrespective of the histological grade. In the high-grade astrocytomas with a Ki-67 labeling index of five and above, 81% of those tumors were hsp27 positive.5. Thus, a large number of human astrocytomas express hsp27, and hsp27 expression correlates with histological grades of astrocytoma and with tumor growth fractions. This being the case, hsp27 is likely to have a role in the growth of human astrocytomas.

Dose optimization and indication of linac radiosurgery for brain metastases

PURPOSE The authors have examined treatment effects of linear accelerator based radiosurgery for brain metastases. Optimal doses and indications were determined in an attempt to improve the quality of life for terminal cancer patients. METHODS AND MATERIALS Ninety-two patients with 162 lesions were treated with Linac radiosurgery for brain metastases between April 1993 and September 1998. To determine prognostic factors, risk factors for recurrence, and appearance of new lesions, univariate and multivariate analyses were performed. To compare the local control between the high-dose (minimum dose > or =25 Gy: prescribed to the 50-80% isodose line) and low-dose (minimum dose <25 Gy) irradiated groups, matched-pairs analysis was performed. RESULTS Median survival time was 11 months. In univariate analysis, extracranial tumor activity (p<0.001) and Karnofsky Performance Status (KPS) (p = 0.036) were two significant predictors of survival. In multivariate analysis, the status of an extracranial tumor was the single significant predictor of survival (p = 0.005). Minimum dose was the single most significant predictor of local recurrence in univariate, multivariate, and matched-pairs analyses (p<0.05). As to the appearance of new lesions, activity of extracranial tumors was a significant predictor (p<0.05). Side effects due to radiosurgery were experienced in 4 of 92 cases (4.3%). CONCLUSIONS We concluded that brain metastases patients should be irradiated with > or =25 Gy, when extracranial lesions are stable and longer survival is expected. Combined surgery and conventional radiation may have little advantage over radiosurgery alone when metastatic brain tumors are small and extracranial tumors are well controlled. When extracranial tumors are progressive, the rate of appearance of new lesions in other nonirradiated locations becomes higher. In such cases, careful follow-up is required and a combination with whole brain irradiation should be considered.

PROTECTIVE ROLE OF GLUTATHIONE SYNTHESIS ON RADIATION-INDUCED DNA DAMAGE IN RABBIT BRAIN

Abstract1. Radiotherapy has attracted increasing interest in recent years. It is known that ionizing radiation induces oxygen radical injury, whereas oxidative stress by the radiation can cause cellular responses to defense cellular injury. In this study, the metabolism of antioxidants in response to ionizing radiation to the brain was studied in the brain using experimental rabbits.2. Ionizing radiation to the hemicerebrum caused an increase in the levels of glutathione (GSH) and the activity of a GSH synthesizing enzyme, γ-glutamylcysteine synthetase (γ-GCS), and Cu,Zn-superoxide dismutase (Cu,Zn-SOD). Ionizing radiation also induced DNA-damage estimated by the formation of 8-hydroxydeoxyguanosine. These changes were dependent on the radiation dose.3. Previous intrathecal-administration of buthionine sulfoximine (100 μM), a specific inhibitor of γ-GCS, increased DNA damage by radiation in the radiated hemicerebrum. That of S-methyl GSH, on the other hand, resulted in a significant reduction of DNA damage by radiation.4. These results suggest that synthesis of GSH and Cu,Zn-SOD is responsive to ionizing radiation and this induction of antioxidants may play a role in reducing tissue damage in radiotherapy.

Immunohistochemical expression of the estrogen receptor‐related antigen (ER‐D5) in human intracranial tumors

Background. Expression of the estrogen receptor‐related antigen (ER‐D5) has been reported in some normal and neoplastic tissues. The authors evaluated the expression of ER‐D5 in 143 intracranial tumors of different histologic types.

Incidence and Causes of Intracranial Hemorrhage in Infancy: A Prospective Surveillance Study after Vitamin K Prophylaxis

In order to evaluate the effect of vitamin K prophylaxis on the incidence of intracranial hemorrhage (ICH) in infants aged from 1 week to 12 months, a prospective surveillance study, from 1974 to 1988, was performed on the well-defined population of Nagasaki Prefecture, Japan. The incidence of ICH in infancy markedly decreased, from 34.3/100,000 to 10.1/100,000 live births, with the oral administration of vitamin K2 at both birth and 1 week, or with additional supplementation at 1 month of age. The diminished incidence was attributed to the decreased occurrence of acute ICH due to late hemorrhagic disease (LHD), a late onset form of vitamin K deficiency, and chronic subdural hematoma. On comparing the possible etiological factors, and clinical and laboratory findings between these 2 groups, it became apparent that chronic subdural hematoma shared some etiological factors (such as breast-feeding, liver dysfunction and no supplementation of vitamin K) with LHD. Furthermore, chronic subdural hematoma developed in some patients who had previously had acute ICH due to LHD. These findings suggest that coagulopathy due to vitamin K deficiency, including LHD, is causally related in the majority of, if not all, cases of chronic subdural hematoma without any history of trauma or central nervous system infections.

Narrow photon beam dosimetry for linear accelerator radiosurgery

The dosimetric characteristics of linear accelerator radiosurgery for 10-MV X-ray were measured. Measurement of the relative output factor and tissue maximum ratio with a microchamber produced results equivalent to those of measurement with X-ray film. The 80% isodose level width measured with the microchamber was significantly smaller than that measured with the X-ray film. For the measurement of relative output factor and tissue maximum ratio, a microchamber seems to be the more appropriate choice. X-Ray film was found to be suitable for beam profile measurement.

Progressive perianeurysmal edema preceding the rupture of a small basilar artery aneurysm.

We herein report the first case of progressive perianeurysmal edema preceding the rupture of a small saccular aneurysm, without any intervention or intraluminal thrombosis. A 71-year-old woman was incidentally noted to have a cerebral aneurysm (5mm in diameter) at the lower basilar artery. Twelve months later, magnetic resonance (MR) imaging showed a T2-elongated area around a dome of the aneurysm buried in the brain stem, suggesting perianeurysmal edema formation. Interestingly, the edema progressed with the formation of a bleb, in addition to an increase in size of the aneurysm over the following 3-year period. The aneurysm eventually ruptured as a brain stem hemorrhage without any subarachnoid clots 3 days after the final check-up with MR imaging, by which a significant increase of edema formation with an increase in size of the aneurysm and a marked expansion of the bleb was observed. These findings raise the possibility that bleb formation and an enlargement of a small cerebral aneurysm might also be associated with perianeurysmal edema and a subsequent aneurysmal rupture. In addition to the pulsatile flow and/or compression from the expanded aneurysm, local inflammation in the aneurysm wall may play an important role in such edema formation.

MRI of intracranial meningeal malignant fibrous histiocytoma

Abstract We describe the CT and MRI findings in a patient with primary intracranial meningeal malignant fibrous histiocytoma (MFH). CT delineated the anatomical relations and MRI aided in tissue characterisation. To our knowledge, this is the first report describing the MRI findings in primary intracranial meningeal MFH.