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Aim: To evaluate the ability of arterial spin labelling (ASL) magnetic resonance imaging (MRI) in differentiating primary central nervous system lymphoma (PCNSL) from atypical high-grade glioma (HGG), as well as exploring the underlying pathological mechanisms., Methods and Materials: Twenty-three patients with PCNSL and 17 patients with atypical HGG who underwent ASL-MRI were identified retrospectively. Absolute cerebral blood flow (aCBF) and normalised cerebral blood flow (nCBF) values were obtained, and were compared between PCNSL and atypical HGG using the Mann-Whitney U-test. The performance in discriminating between PCNSL and atypical HGG was evaluated using receiver-operating characteristics analysis and area-under-the-curve (AUC) values for aCBF and nCBF. The correlation between microvessel density (MVD) and aCBF was determined by Spearman's correlation analysis., Results: Atypical HGG demonstrated significantly higher aCBF, nCBF, and MVD values than PCNSL (p<0.05). The diagnostic accuracy of discriminating PCNSL from atypical HGG showed AUC=0.877 (95% confidence interval [CI] 0.735-0.959) for aCBF, and AUC=0.836 (95% confidence interval [CI] 0.685-0.934) for nCBF. There was a moderate positive correlation between aCBF values of region of interest (ROI >30 mm 2 ) in the enhanced area and MVD values (rho=0.579, p=0.0001), and a strong positive correlation between aCBF values MVD based on "point-to-point biopsy" (rho=0.83, p=0.0029). Interobserver agreements for aCBF and nCBF were excellent (ICC >0.75)., Conclusions: ASL perfusion MRI is a useful imaging technique for the discrimination between atypical HGG and PCNSL, which may be determined by the difference of MVD between them., (Copyright © 2018 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Purpose: To evaluate the usefulness of pseudo-continuous arterial spin labeling (pCASL) imaging in differentiating high-grade gliomas from lymphomas and in noninvasively predicting genetic biomarkers in high-grade gliomas., Materials and Methods: Twelve glioblastoma multiforme (GBM), 3 anaplastic astrocytoma (AA), 5 recurred GBM, and 9 lymphoma patients underwent conventional MR and pCASL imaging. On pCASL perfusion map, mean absolute tumor blood flow (mTBF) was calculated from five regions of interest (ROIs) within the enhancing portion of the tumor. Relative TBF (rTBF = mTBF/mBFgm × 100) was also calculated. mTBF and rTBF of high-grade gliomas and lymphomas were compared using unpaired Student's t-test and receiver operating characteristic (ROC) analysis. Additionally, the association of TBF and six immunohistochemically confirmed genetic biomarkers was analyzed by Pearson correlation analysis in the group of high-grade gliomas., Results: Both mTBF and rTBF of the high-grade gliomas were significantly higher than those of the lymphomas: 92.1 ± 34.7 versus 53.6 ± 30.5 mL/min/100 mg (P = 0.008) and 182.3 ± 69.5 versus 92.5 ± 44.9 (P = 0.002), respectively. Only epidermal growth factor receptor (EGFR) expression status showed a significant positive correlation with mTBF(P = 0.015) and rTBF(P = 0.007)., Conclusion: pCASL imaging may facilitate differentiation of high-grade gliomas from lymphomas and prediction of EGFR expression status in high-grade gliomas., (Copyright © 2013 Wiley Periodicals, Inc.)

Objective: Smear preparations are useful tools from which to diagnose brain tumours intraoperatively. Although vascular proliferation is histologically a key feature of high-grade astrocytoma, the characteristics of tumour vessels in smear preparations have not been determined., Methods: We examined the density and morphological parameters (area, width, nuclear layer and branches of vessel wall) of tumour vessels in squash smears of 43 primary astrocytomas (grade II diffuse astrocytomas, n=9; grade III anaplastic astrocytomas, n=13; grade IV glioblastomas, n=21) and normal brain tissues (n=11)., Results: Vessel density and all morphological parameters were significantly higher in grade IV than in the other grades of tumours and in normal brain tissue. Vessel area, width and nuclear layer were greater in grade III than in normal brain tissue. The sensitivity and specificity of these vessel parameters for astrocytomas were 75-100% and 82-100%, respectively., Conclusions: Tumour vessel evaluations from squash smears provide useful information for the intraoperative diagnosis and grading of astrocytic tumours., (© 2010 Blackwell Publishing Ltd.)

Angiogenesis plays an important role in the progression of astrocytic tumors and its evaluation is a major prognostic factor. Although the form of proliferating vessels ranges from fine capillaries to well-developed vascular structures with a smooth muscle layer, the characteristics of vascular smooth muscle cells (SMCs) are not understood in detail. We therefore examined the density, size and shape of tumor vessels, as well as CD34-immunoreactive (CD34-Vs) or α-smooth muscle actin-immunoreactive (SMA-Vs) vessels in 46 primary astrocytomas (grade II diffuse astrocytomas, n=11, grade III anaplastic astrocytomas, n=15, grade IV glioblastomas, n=20) and in normal brain tissues from 10 autopsies. We also examined the expression of high molecular weight caldesmon (h-CD, a marker of the contractile phenotype of smooth muscle) and of platelet-derived growth factor receptor β (PDGFR-β). The SMA-Vs were significantly more dense and larger in grade IV than grade III, whereas those of CD34-Vs did not differ between grade III and IV. Changes in the shape of CD34-Vs and SMA-Vs correlated with histological grading. The expression of h-CD was reduced, whereas that of PFGFR-β was increased in high grade-astrocytomas. Kaplan-Meier analysis indicated that the density of SMA-Vs, the size of both CD34 and SMA-Vs and PDGFR-β expression were significant prognostic factors. These findings suggest that SMA-Vs are significantly associated with the progression of astrocytomas and that these vessels provide useful information for the histological diagnosis and survival of patients with these types of brain tumors.

Aims: Secreted protein, acidic and rich in cysteine (SPARC) is a regulator of cell-matrix interaction and has been associated with tumour stage and patient survival in various malignancies. As no large-scale study has yet been undertaken, we investigated human brain and astrocytomas for SPARC expression and associations with tumour grade, proliferation, vascular density and patient survival., Methods: A spectrum of 188 WHO grade I-IV astrocytic tumours and 24 autopsy cases were studied by immunohistochemistry for SPARC, MIB-1 proliferation index and CD31-positive vessels. SPARC protein expression was confirmed by quantitative real-time polymerase chain reaction and Western blot in 13 cases., Results: In normal brain, SPARC is expressed in cortical marginal glia, cerebellar Bergmann glia and focally in white matter but is absent in neurones or vessels. High SPARC expression levels in the cytoplasm of astrocytic tumour cells decreased with the grade of malignancy but showed an increase with grade of malignancy in tumour vessels. SPARC negatively correlated with tumour proliferation but not with vascular density. While cytoplasmic SPARC staining was not associated with survival, vascular SPARC showed a significant association in the group of grade II-IV tumours (P = 0.02) and also in grade II astrocytomas alone (P = 0.01) with vascular SPARC associated with worse prognosis., Conclusions: SPARC is highly expressed in astrocytomas and decreases with tumour progression. We confirm an association of increased SPARC expression and decreased proliferation. While there is no association between the level of SPARC in the tumour cells and patient survival, increased tumour vascular SPARC expression is associated with decreased patient survival.

We utilized blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) and MR perfusion imaging methods to study the influence of brain tumor neovascularity on the BOLD fMRI activation volume in the primary motor cortex (PMC). The results from 57 brain tumor cases demonstrated that, for grade IV gliomas only, decreases in the BOLD fMRI activation volumes within the ipsilateral PMC, when compared with that observed in the contralateral PMC, correlated with increases in the relative regional cerebral blood volume (rCBV) in the PMC. In addition, relative increases in the activation volumes, corresponding to decreases in the rCBV, exhibited a linear dependence on the distance between the grade IV glioma and PMC. These findings lend support to the hypothesis that decreases in the fMRI activation volumes adjacent to a GBM may, in part, be due to the increased contribution of aberrant tumor neovascularity, with the resultant de-coupling of blood flow from neuronal activity. The nature of the relationship between the resulting activation volumes and adjacent tumor characteristics is complex, but is found to be dependent on the tumor grade and type, as well as the distance of the tumor to the PMC.

Purpose: To determine whether cerebral blood volume (CBV) and cerebral blood flow can predict the response of high-grade gliomas to radiotherapy (RT) by taking into account spatial heterogeneity and temporal changes in perfusion., Methods and Materials: Twenty-three patients with high-grade gliomas underwent conformal RT, with magnetic resonance imaging perfusion before and at Weeks 1-2 and 3-4 during RT. Tumor perfusion was classified as high, medium, or low. The prognostic values of pre-RT perfusion and the changes during RT for early prediction of tumor response to RT were evaluated., Results: The fractional high-CBV tumor volume before RT and the fluid-attenuated inversion recovery imaging tumor volume were identified as predictors for survival (p = 0.01). Changes in tumor CBV during the early treatment course also predicted for survival. Better survival was predicted by a decrease in the fractional low-CBV tumor volume at Week 1 of RT vs. before RT, a decrease in the fractional high-CBV tumor volume at Week 3 vs. Week 1 of RT, and a smaller pre-RT fluid-attenuated inversion recovery imaging tumor volume (p = 0.01)., Conclusion: Early temporal changes during RT in heterogeneous regions of high and low perfusion in gliomas might predict for different physiologic responses to RT. This might also open the opportunity to identify tumor subvolumes that are radioresistant and might benefit from intensified RT.

Samples were taken from supratentorial gliomas border and normal brain autopsy which were divided into four groups, these including eight cases normal brain tissues, 30 cases of astrocytomas, 25 cases of anaplastic astrocytomas and 22 cases of glioblastomas. Cathepin B (CB) expression and microvessel density (MVD) were determined with immunohistochemical studies. Staining results of CB was scored according to the percentage of positive cells, graded as negative (-), weak (+), moderate (++), and strong (+ + +). MVD was analyzed by Weidner's revised technique. CB positive staining was negative in eight cases of normal brain tissue. Only 9 out of 30 cases of astrocytomas showed a low percentage of positive cells that were stained in a light, diffuse cytoplasmic pattern (score +). Twenty-two out of 35 cases of anaplastic astrocytomas showed positive light, granular staining pattern, it including five samples (score +), and 17 samples (score + +). In contrast, all 22 cases of glioblastomas were stained all, and it was present in a course, granular staining pattern with an intensity of score (+ +) of two sample, and score (+ + +) of 20 samples. Positive staining tumor cells were found in extracellular matrix (ECM), basement membrane (BM), and the endothelial cells of blood vessels were also positive stained. Along with elevating glioma grade, CB expression and MVD value were both increased. Therefore, it showed MVD value was positive correlated with expression of CB. It highly suggested that CB and angiogenesis plays an important role in glioma progression.

Purpose: To characterize human gliomas using T1-weighted dynamic contrast-enhanced MRI (DCE-MRI), and directly compare three pharmacokinetic analysis techniques: a conventional established technique and two novel techniques that aim to reduce erroneous overestimation of the volume transfer constant between plasma and the extravascular extracellular space (EES) (Ktrans) in areas of high blood volume., Materials and Methods: Eighteen patients with high-grade gliomas underwent DCE-MRI. Three kinetic models were applied to estimate Ktrans and fractional blood plasma volume (vp). We applied the Tofts and Kermode (TK) model without arterial input function (AIF) estimation, the TK model modified to include vp and AIF estimation (mTK), and a "first pass" variant of the TK model (FP)., Results: KTK values were considerably higher than KmTK and KFP values (P <0.001). KmTK and KFP were more comparable and closely correlated (rho=0.744), with KmTK generally higher than KFP (P <0.001). Estimates of vp(mTK) and vp(FP) also showed a significant difference (P <0.001); however, these values were very closely correlated (rho=0.901). KTK parameter maps showed "pseudopermeability" effects displaying numerous vessels. These were not visualized on KmTK and KFP maps but appeared on the corresponding vp maps, indicating a failure of the TK model in commonly occurring vascular regions., Conclusion: Both of the methods that incorporate a measured AIF and an estimate of vp provide similar pathophysiological information and avoid erroneous overestimation of Ktrans in areas of significant vessel density, and thus allow a more accurate estimation of endothelial permeability.

Angiopoietins (Ang1 and Ang2) modulate the activity of the endothelial cell (EC)-specific receptor tyrosine kinase Tie2, which together with vascular endothelial growth factor (VEGF-A) and its EC-specific receptors, VEGFR1 and VEGFR2, regulate normal physiological vessel development. The functional role of angiopoietins in tumor angiogenesis, in particular astrocytoma angiogenesis, remains unclear. In this study, we focus on the specific contribution of Ang1 to the vascular growth of glioblastoma multiforme (GBM) and its interactive role with VEGF-A. Subcutaneous and intracranial GBM xenografts were generated using 3 established astrocytoma cell lines (U87, U373, and U343) that were transfected to stably over-express Ang1. GBM xenografts were also generated to express low levels of VEGF-A and high Angl. We found that Ang1 increases the vascular growth of both subcutaneous and intracranial xenografts of GBM by approximately 3-fold. However, the increased vascular growth was only seen in xenografts with concurrent VEGF-A elevation, since decreasing VEGF-A expression resulted in a loss of the pro-angiogenic growth advantage seen with Ang1. Collectively, our data suggest that Ang1 regulates GBM vascularity in a VEGF-A dependent manner, synergizing the initial pro-angiogenic response that is triggered by VEGF-A and promoting the vascular growth of GBM.

Objective: Gliomas account for most primary brain tumors in adults, and survival correlates with the grade and vascularity of the tumor. The degree of tumor-related angiogenesis seems to be a significant predictor of tumor progression, recurrence, and metastatic spread in a variety of malignant diseases, including brain tumors. Our study's objective was to quantify the levels of two angiogenic factors, basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF), in the cerebrospinal fluid (CSF) and serum of patients with gliomas and to correlate these levels with tumor grade, vascularity, and overall survival., Methods: Twenty-six patients with the diagnosis of cerebral glioma (19 high-grade, 7 low-grade) comprised the study group. Ten patients with communicating hydrocephalus served as controls. Levels of VEGF and bFGF in the CSF and serum were determined using enzyme-linked immunosorbent assay analysis. Tumor vascularity was graded qualitatively using immunohistochemical staining for CD34. Nonparametric statistical techniques were used for data analysis., Results: Median levels of bFGF and VEGF in the CSF were significantly higher in patients with high-grade glioma as compared with patients with low-grade glioma or hydrocephalus (bFGF levels, 52, 26, and 24 ng/ml, respectively, P < 0.0001; VEGF levels, 17.6, 7.2, and 8.3 ng/ml, respectively, P < 0.005). A significant correlation was found comparing CSF levels of bFGF with levels of VEGF (P < 0.001). The levels of the angiogenic factors in the CSF correlated with the degree of tumor vascularity and were adversely associated with patient survival. Serum levels of the angiogenic factors showed no correlation to tumor grade, vascularity, or survival., Conclusion: Our data suggest that CSF levels of bFGF and VEGF may serve as an additional marker for tumor grading and vascularity and may help predict survival.

Background and Purpose: The GliaSite system delivers local, high radiation after brain tumor resection. We describe the imaging appearance of the device and the changes it causes., Methods: Eight patients with brain tumors were treated with this system. After surgery, all underwent MR imaging, and one underwent CT. Five were examined 1 month after radioactive unloading and every 2 months thereafter (total, 6-9 months). Initial studies were assessed for balloon appearance and complications; subsequent studies, for signal intensity and enhancement. Three patients underwent multivoxel proton MR spectroscopy, and one underwent MR perfusion study. Spectra were reviewed for metabolites suggesting tumor; perfusion studies were reviewed for increased relative cerebral blood volume and flow., Results: CT showed the hyperattenuating balloon with considerable artifact. All MR images showed the device and adjacent brain. Follow-up studies showed enhancement and T2 hyperintensity in five patients. In one, enhancement progressively disappeared with no evidence of tumor recurrence. Another patient had progressive enhancement and low relative cerebral blood volume and flow; biopsy showed necrosis and inflammation. One patient had progressive enhancement and high choline levels (proved anaplastic astrocytoma). In another, T2 signal intensity and contrast enhancement progressed owing to tumor and bacterial infection. The last patient had a high choline level (proved radionecrosis); enhancement progressed over 5 months. In three, the device was removed early because of bleeding, mass effect, and therapeutic changes (no follow-up)., Conclusion: Good balloon visualization was possible with MR imaging. After brachytherapy, all patients developed T2 hyperintensity; stable or progressive enhancement occurred with tumor recurrence and radionecrosis. High choline levels were suggestive of, but not necessarily diagnostic of, tumor.

Positron emission tomography (PET) using methyl-[(11)C]- l-methionine ([(11)C]MET) is a useful tool in the diagnosis of brain tumours. The main mechanism of [(11)C]MET uptake is probably increased transport via the L-transporter system located in the endothelial cell membrane. We used [(11)C]MET-PET and microvessel count in glioma specimens to investigate whether the increased amino acid uptake is related to angiogenesis. Twenty-one patients with newly diagnosed and histologically confirmed glioma were investigated with [(11)C]MET-PET before open surgery. [(11)C]MET uptake was determined within an 8-mm region of interest in the area of the tumour showing the highest uptake, and the ratio to uptake in the corresponding contralateral region was calculated. To measure angiogenesis, immunostaining with factor VIII antibody was applied to sections from tumour tissue, and highlighted microvessels were counted in the area of highest vascularisation. In the entire patient group, a positive correlation was found between microvessel count and [(11)C]MET uptake (Spearman: r=0.89, P<0.001). This correlation was also significant in subgroups of patients [patients with grade II and III astrocytomas (Spearman: r=0.77, P<0.01) and patients with glioblastoma (Spearman: r=0.64, P<0.05)]. Angiogenesis, as assessed by microvessel count, and increased amino acid uptake, as assessed by [(11)C]MET-PET, are closely related events in gliomas. [(11)C]MET-PET offers a direct measure of amino acid transport and an indirect measure of microvessel density. [(11)C]MET-PET might be a useful tool to select potential responders to anti-angiogenic therapy and to monitor patients during such therapy.

Background: Growth and expansion of gliomas are highly dependent on vascular neogenesis. An association of microvascular density and tumour energy metabolism is assumed in most human gliomas. The purpose of this investigation was to characterize a series of gliomas by intra-operative near-infrared spectroscopy (NIRS), and to elucidate the relationship between microvascular blood volume (BV), oxygen saturation (SaO(2)), histology and patient survival., Method: The study included 13 patients with gliomas, in whom complete tumour resection according to postoperative magnetic resonance imaging criteria was achieved. Intra-operatively, one low grade astrocytoma, five anaplastic astrocytomas and seven glioblastomas with the ipsilateral cortex were investigated by NIRS revealing capillary BV (total haemoglobin) and SaO(2). Intratumoural BV (tBV) and SaO(2) (tSaO(2)) were additionally used in relation to histology and survival., Findings: The mean tBV of the astrocytomas was 4.96 mg/ml compared to 18.40 mg/ml in the glioblastoma group. Mean tSaO(2) was 36% in the astrocytoma group and 52% in the glioblastomas, respectively. Both tBV and tSaO(2) were significantly higher (p<0.01) in the glioblastoma group. Median survival time was shortest for patients with glioblastoma (12.5 months), with tBV >10/mg/ml (10 months), and tSaO(2) >50% (10 months). Longest median survival times were observed in the astrocytoma group (32.5 months), in patients with Tbv <10/mg/ml (30 months), and tSaO(2) <50% (27.5 months). The differences were highly significant (p<0.01)., Interpretation: Intra-operative characterization of gliomas by NIRS is feasible. High tBV represents extensive angiogenetic activity of the tumour, whereas high tSaO(2) may be result of non-oxidative glucose metabolism with less oxygen extraction from the capillary bed of the tumour. However, the extent of tBV and tSaO(2) are both of possible prognostic value thus resulting in additional information about the tumour.

Vascular endothelial growth factor (VEGF) is thought to promote tumor growth and angiogenesis. Whereas VEGF is up-regulated in only a portion of anaplastic astrocytoma (AA), it is overexpressed in most glioblastoma multiforme (GBM), and the level of expression is correlated with grade of glioma. To explore the possibility that VEGF may act as a driving force in the progression of AA to GBM, the VEGF isoforms VEGF(121) and VEGF(165) were overexpressed in genetically modified, mutant H-Ras-transformed human astrocytes that on intracranial implantation form AA-like tumors. The ability of the VEGF isoforms to stimulate growth, angiogenesis, oxygenation, and the formation of necrotic GBM-like tumors was then monitored. The parental mutant H-Ras-modified astrocytes expressed four times more endogenous VEGF than normal human astrocytes, but on intracranial implantation formed hypovascular, hypoxic, small AA-like tumors. Whereas these modest levels of VEGF overexpression were insufficient to drive oxygenation and GBM formation, an additional 8-fold increase in VEGF expression mediated by retroviral infection with constructs encoding either VEGF (121) or VEGF (165) resulted in cells which, after intracranial implantation, formed tumors that were larger, more vascular, and better oxygenated than those formed by the mutant H-ras parental cells. However, the tumors formed by the cells expressing exogenous VEGF (121) or VEGF (165) retained the phenotype of AA, lacking areas of necrosis that are the hallmark of the GBM phenotype. These results suggest that whereas the VEGF(121) and VEGF(165) isoforms can contribute to glioma vascularization, oxygenation, and growth, they do not in and of themselves drive the formation of the GBM phenotype.

Rationale and Objective: To evaluate the vascularity and vascular leakage of well-enhanced gliomas by double-echo dynamic magnetic resonance (MR) imaging., Materials and Methods: Eight patients with glioblastoma multiforme (GBM) and two patients with juvenile pilocytic astrocytoma (JPA) were studied. Double-echo dynamic MR imaging was utilized to separate the T2* shortening effect and the T1 shortening effect. The former was represented by the vascularity index, and the latter was represented by the leakage index. These indexes were compared with histopathologic data., Results: The mean vascularity index of the GBM was higher than that of the JPA (mean +/- SD, 3.48 +/- 1.57 [GBM] versus 0.51 +/- 0.29 [JPA]), and the mean leakage index of the JPA was higher than that of the GBM (1.35 +/- 0.87 [JPA] versus 0.27 +/- 0.15 [GBM]). Abundant vascularity was noted in the tight interstitial space in the pathologic specimen of GBM. Conversely, sparse vasculature was observed in the wide interstitial space in the pathologic specimen of JPA., Conclusion: This method may enable better characterization of grade in well-enhanced glioma by providing the information on the vascularity and leakage indexes.

Malignant brain tumors have been shown to decrease O2 and blood flow resulting in hypoxia and low perfusion that in turn reduce radiation sensitivity and access by chemotherapeutic agents. Spinal cord stimulation (SCS) is a procedure that has been used quite successfully in the treatment of pain and ischemic syndromes. In the present study the authors applied the method and, with polarographic probes inserted in the tumor sites, measured the changes in tissue oxygenation and hypoxia in two separate tumor areas in three patients with high-grade astrocytomas. The results of the SCS indicated that overall tumor oxygenation increased by 90% (from 13.2+/-9.4 mm Hg to 25.1+/-9.6 mm Hg; p = 0.013); the percentage of moderately hypoxic values (< 10 mm Hg) decreased by 55% (from 48.6+/-20.1% to 22+/-13.3%; p = 0.026); and the percentage of considerably hypoxic values (< 5 mm Hg) decreased by 45% (from 28+/-20.3% to 15.5+/-15%; p = 0.018). In this report the authors describe a potential novel application of SCS, and the preliminary results suggest that tumor tissue oxygenation and hypoxia are significantly improved as a result. If these findings are confirmed, the method may be applicable as an adjuvant to radiotherapy and chemotherapy regimens.

Object: Evidence from recent in vitro studies indicates that reactivation of telomerase, the enzyme that synthesizes the telomere ends of chromosomes, is a crucial event in the unlimited clonal expansion of endothelial cells that precedes the neoplastic conversion of these cells. It is known that high-grade gliomas express telomerase and that, in these neoplasms, proliferating endothelial cells may undergo transformational changes with development of sarcomatous components within the primitive tumor. To assess whether telomerase is involved in the endothelial cell proliferation that characterizes brain tumor angiogenesis, the authors investigated at the single-cell level the expression of messenger (m)RNA for the human telomerase catalytic subunit human telomerase reverse transcriptase (hTERT) by vascular cells of astrocytic tumors., Methods: The in situ hybridization (ISH) method was performed by processing histological sections with specific riboprobes for hTERT and for c-myc, an oncogene that is known to upregulate hTERT. Results of the ISH studies were compared with proliferative activity, as estimated by Ki-67 immunostaining. The expression of hTERT mRNA by vascular endothelial cells was related to the histological grade of the tumor because it was detected in five (29%) of 17 low-grade astrocytomas, nine (56%) of 16 anaplastic astrocytomas, and 19 (100%) of 19 glioblastomas multiforme (GBMs). Expression of c-myc mRNA was strictly correlated with that of hTERT mRNA. In low-grade astrocytomas and anaplastic astrocytomas, a dissociation was noted between hTERT mRNA expression and the proliferation rate of endothelial cells. Conversely, GBMs displayed a significant correlation between the level of hTERT mRNA expression and endothelial cell proliferation. Data from an in vitro assay in which human umbilical vein endothelial cells were stimulated to proliferate by adding vascular endothelial growth factor and an ISH study of newly formed vessels surrounding brain infarcts confirmed that expression of hTERT mRNA does not merely reflect the proliferative status of endothelial cells but represents a specific feature of brain tumor neovascularization., Conclusions: The results of this study are consistent with a role of telomerase in the angiogenesis of astrocytic tumors. Expression of hTERT mRNA by tumor vascular cells is an early event during the progression of astrocytic tumors, which precedes endothelial cell proliferation and may represent a first sign of dedifferentiation. Other than elucidating the mechanisms of tumor angiogenesis, these results encourage research on antitelomerase drugs for the treatment of malignant gliomas.

Thymidine phosphorylase (TP) has strong angiogenic activity and is overexpressed in a wide variety of malignant tumors. To elucidate the role of TP in human astrocytic tumors, we immunohistochemically investigated the expression of TP in 62 astrocytic tumors (12 astrocytomas, 12 anaplastic astrocytomas and 38 glioblastomas). Fifty-five astrocytic tumors (88.7%) were immunopositive for TP. The level of TP-expression was significantly correlated with the malignancy grade of astrocytic tumors; most of malignant gliomas highly expressed TP, while a small number of cells were positive in low grade astrocytomas (p < 0.001). Using double-immunostaining, we clarified that TP-expression was predominantly detectable in macrophages. There was no significant correlation between MIB-1 labeling index and TP-expression. However, TP-expression and the microvessel density were well correlated. These suggest that TP, mainly produced by the infiltrated macrophages, may play an important role in the progression of astrocytic tumors via neovascularization. Inhibitor of TP may represent a therapeutic modality for treating malignant gliomas.

We monitored the expression of glycan-binding sites on a panel of 10 biotinylated neoglycoconjugates by means of quantitative computer-assisted microscopy to further study the molecular mechanisms in the extensive infiltration of the surrounding brain parenchyma by most astrocytic tumors. Three distinct histological compartments were analyzed for each of the 108 astrocytic tumors (15 pilocytic astrocytomas (WHO grade I), 25 astrocytomas (WHO grade II), 30 anaplastic astrocytomas (WHO grade III), and 38 glioblastomas (WHO grade IV) included in our series. These compartments were tumors (nonperivascular tumor astrocytes), perivascular tumor astrocytes, and blood vessel walls. Clear differences were observed between the pilocytic and the diffuse astrocytic tumors. Furthermore, malignant progression in the latter category was paralleled by a decrease in cells' ability to bind distinct sugar epitopes, especially the D-GalNAc(alpha1-3)-D-GalNAc-beta1-R determinant of the Forssman pentasaccharide in tumors, the alpha-L-fucose in perivascular tumor areas, and the beta-D-glucose in tumor vessel walls. Markedly, the level of binding site expression for alpha-D-mannose decreased in the tumors, the perivascular tumor areas, and the vessel walls. These glycohistochemical results imply the functional relevance of protein-carbohydrate interactions in this tumor system.

We studied the relationships among vascular endothelial growth factor (VEGF), its receptors (Flt1 and Flk1), and MIB-1. Their expression in 47 diffusely infiltrating astrocytomas obtained at surgery or autopsy was investigated by the ABC method and analyzed quantitatively. The positive rate of VEGF in tumor cells was higher than that in endothelial cells, and Flk1 was lower in tumor cells (P < 0.01, 0.01), whereas Flt1 in both tumor cells and endothelial cells was found at similar levels (P > 0.05). In tumor cells, VEGF became high with increased histological grades (P < 0.01). whereas both Flt1 and Flk1 were higher in grade 4 than in grades 2 and 3 (P < 0.01, 0.05). VEGF, Flt1, and Flk1 in endothelial cells were also highly expressed in grade 4 (P < 0.01). The distribution of MIB-1-positive nuclei in grade 4 was similar to VEGF, and the percent of positivity from grade 2 to grade 4 also increased (P < 0.01). There was a linear positive correlation between VEGF and both Flt1 and Flk1 in both tumor cells and endothelial cells (P < 0.01). So was the percent of positivity with VEGF, Flt1, and Flk1 in tumor cells and endothelial cells (P < 0.01). The experiment suggests that VEGF may act as a growth factor for both endothelial cells and tumor cells. VEGF, Flt1, and Flk1 can be considered as indicators of the malignancy potential of diffusely infiltrating astrocytomas. The expression of VEGF and the two receptors may be affected by the proliferative activity of tumor cells.

Growth of human malignant gliomas is stringently dependent on an angiogenic process that probably involves vascular endothelial growth factor (VEGF). Expressions of mRNA coding for the different forms of VEGF were analyzed in surgical specimens from human astrocytomas. Low levels of placental growth factor (PGF) and VEGFC mRNA were observed in polymerase chain reaction, but not in Northern blot experiments. VEGF mRNA was found in some but not all grade and grade IV astrocytomas. VEGFB mRNA was observed in all tissue samples analyzed irrespective of the tumor grade. A new splice variant of VEGFB (VEGFB155) that lacks exons 5 and 6 is described. Expressions of VEGF mRNA in cultured glioblastomas cells were upregulated by hypoxia, but the sensitivity of the cells to hypoxia was reduced as compared with normal rat astrocytes. VEGF expression was depressed by dexamethasone. Expressions of VEGFB mRNA were affected neither by hypoxia nor by dexamethasone. The results indicate a coexpression of VEGF mRNA and VEGFB mRNA in human astrocytomas. Expression of VEGFB is markedly different from that of VEGF. Possible roles of VEGFB as a cofactor for hypoxia-induced angiogenesis in human astrocytomas are discussed.

Thymidine phosphorylase (TP) has been implicated as a potent angiogenic factor and a prognostic factor in various human solid tumors. We investigated the expression of TP in a series of human astrocytic tumors using immunohistochemistry, enzyme-linked immunosorbent assay, and reverse transcriptase/polymerase chain reaction (RT-PCR) analysis. A total of 63 astrocytic tumors [27 glioblastomas (GBM), 19 anaplastic astrocytomas (AA), 17 low-grade astrocytomas (LGA)] and 5 normal brain tissues were immunohistochemically stained with antibodies to TP, vascular endothelial growth factor (VEGF), p53, MIB-1, and factor-VIII-related antigen. They were also evaluated for the degree of apoptosis by a ApopTag kit. Ten tumors (5 GBM, 2 AA, 3 LGA) and 3 normal brain tissues were evaluated for their expression of VEGF and TP by RT-PCR analysis. TP was constantly localized in the cytoplasm of astrocytic tumor cells, less intensely in the cytoplasm of vascular endothelial cells, but not in the normal brain. Some of the TP-positive cells were of macrophage origin, but most positive cells were the tumor cells themselves. Vascular density, MIB-1 positivity, p53 positivity, VEGF expression, and the apoptotic index were significantly higher in the TP-positive tumors than in TP-negative tumors. There was a significant correlation between TP and VEGF mRNA expression. In a limited number of glioblastoma cases, the apoptotic index was significantly higher in TP-positive glioblastomas than in TP-negative glioblastomas. In human astrocytic tumors, TP was expressed in the tumor, macrophage, and endothelial cells. TP was a potent angiogenic factor closely associated with cell proliferation and tumor apoptosis.

Aims of the study were: 1. to establish the prevalence of CD44 protein expression in human astrocytomas; 2. to compare the distribution of the extracellular matrix in these tumors; 3. to investigate the relation between CD 44, the extracellular matrix proteins and the histological grade of the tumor. CD44, Type IV Collagen (Col IV), Laminin (LN), Fibronectin (FN), and Tenascin (TN) expression were detected by immunohistochemistry in formalin fixed paraffin embedded tissue samples of 52 astrocytic tumors: 35 glioblastomas (GB), 7 Anaplastic astrocytomas (AA) and 10 astrocytomas (A). The localization of Col IV was observed in the basement membrane of the vessel walls in most of the astrocytomas (88.4%) with a similar pattern obtained with LN staining. 7 of 10 A (70%), 2 of 7 AA (28%) and 9 of 35 GB (25.7%) showed LN positivity. There was a negative correlation between LN expression and tumor grade (p=0.03). FN was either localized in the basement membrane or showed thick multi-layered immunoreactivity of the vessel walls. FN expression was seen in 6 A (60%), 4 AA (57%) and all of 35 GB (100%). The FN distribution was not uniform and its staining intensity showed decrease in GB. 3A (30%), 3 AA (42%), 27 GB (77.1%) showed TN expression in the vessel walls and in some tumor cells of 19 GBs. TN expression was positively correlated with the degree of vascular endothelial proliferation in GB (p<0.05). The expression of CD44s wasseen as plasma membrane positivity of glioma cells in 5 of 10A (50%), 3 of 7AA (42.3%) and 29 of 35 GB (82.8%). The intensity of immunoreaction was quite strong especially near the vessels. There was a good correlation between TN and CD44s expression in human astrocytic tumors (p=0.005). No relationship was observed between GFAP, ECM proteins and CD44s expression. Both CD44s and TN expression showed increase with malignancy in astrocytomas. These findings indicated that the histological malignancy of the astrocytomas was correlated with expression of TN and CD44s. It was suggested that in astrocytomas there was a biological relationship only between CD44 and TN, but none with the other ECM proteins. TN may play a role in angiogenesis in human astrocytic tumors.

Angiopoietin-1 (Ang-1) and its naturally occurring antagonist angiopoietin-2 (Ang-2) are novel ligands that regulate tyrosine phosphorylation of the Tie2/Tek receptor on endothelial cells. Proper regulation of Tie2/Tek is absolutely required for normal vascular development, seemingly by regulating vascular remodeling and endothelial cell interactions with supporting pericytes/smooth muscle cells. We investigated the expression of Ang-1 and Ang-2 in human astrocytomas by in situ hybridization and compared them to the distribution of pericytes/smooth muscle cells by immunohistochemistry for alpha-smooth muscle actin (SMA). Ang-1 mRNA was localized in tumor cells and Ang-2 mRNA was detected in endothelial cells of hyperplastic and nonhyperplastic tumor vessels. Ang-2 was also expressed in partially sclerotic vessels and in vascular channels surrounded by tumor cells in brain adjacent to the tumor. Neither Ang-1 nor Ang-2 was detected in normal brain. Dynamic changes in SMA expression during glioma tumorigenesis appear to progress from fragmentation in early vascular hyperplasia to subsequent reassociation and enhanced expression in later stages of vascular proliferation in hyperplastic complexes in high-grade gliomas. All these vessels displaying dynamic changes in SMA immunoreactivity also expressed Ang-2 mRNA. Moreover, SMA immunoreactive intratumoral vascular channels lacking morphological evidence of hyperplasia also showed upregulation of Ang-2. These results suggest that angiopoietins are involved in the early stage of vascular activation and in advanced angiogenesis, and they identify Ang-2 as an early marker of glioma-induced neovascularization. The association between Ang-2 expression and alterations in SMA immunoreactivity suggests a role for Ang-2 in tumor-associated activation of pericytes/smooth muscle cells., (Copyright 1999 Academic Press.)

Objective: Endothelial nitric oxide synthase (eNOS) may play an important role in the regulation of tumor blood flow and vascular permeability. However, there have been no reports describing alterations of eNOS expression in relation to malignant progression in human astrocytic tumors. We immunohistochemically studied the relationship between eNOS expression in tumor vasculature and malignancy in supratentorial astrocytic tumors., Methods: Tissue samples were obtained from 12 patients with low-grade astrocytomas, 10 with anaplastic astrocytomas, and 17 with glioblastomas. Normal brain tissue samples were obtained from four patients with other brain diseases. Immunohistochemical staining was performed using the avidin-biotin complex method, with polyclonal anti-eNOS antibody, and the levels of eNOS expression in endothelial cells were evaluated as slight, moderate, or intense on the basis of eNOS immunoreactivity. The proliferative potential was assessed as the MIB-1 staining index for tumor cells., Results: The expression of eNOS was slight in all specimens of normal brain tissue, slight in 7 and moderate in 5 specimens of low-grade astrocytoma, slight in 2, moderate in 6, and intense in 2 specimens of anaplastic astrocytoma, and moderate in 5 and intense in 12 specimens of glioblastoma. The MIB-1 staining index (mean+/-standard deviation) was 0.2+/-0.2% for normal specimens, 1.8+/-0.6% for low-grade astrocytomas, 9.6+/-6.9% for anaplastic astrocytomas, and 18.5+/-7.7% for glioblastomas. The MIB-1 staining indices for slight, moderate, and intense eNOS expression were 2.0+/-2.3%, 10.8+/-9.8%, and 16.9+/-7.7%, respectively., Conclusion: Expression of eNOS in tumor vessels was significantly correlated with histological grade and proliferative potential. These findings suggest that astrocytic tumor vessels possess higher activity for nitric oxide production than do normal vessels.

Verotoxin 1 (VT1) is an E. coli elaborated subunit toxin active only against (tumor) cell lines that express the VT1 receptor, globotriaosyl ceramide-Gb3. Astrocytomas can be highly malignant brain tumors that remain refractory to clinical treatment. Some human astrocytoma cell lines are particularly sensitive to VT1 in vitro. To address whether this represents a feasible approach to the elimination of these tumors in man, human astrocytoma tumor xenografts in nude mice were treated with verotoxin. Following a single low-dose intratumoral injection of VT1, complete regression of a 1-cm-diameter tumor within 10 days was observed in all treated animals, without reoccurrence (up to 60 days). Apoptosis was demonstrated in both tumor and vascular cells within the treated xenograft. Verotoxin binding to tumor cells and blood vessels in sections of primary glioblastoma multiforme was found.

Background: Invasion and metastasis is aided by the secretion of guanidinobenzoatase, that cleaves the link peptide to fibronectin, and urokinase plasminogen activator (uPA), which initiates a molecular cascade to activate plasmin and collagenases. This process permits malignant cell migration through the extracellular matrix., Materials: Original human astrocytomas were examined for guanidinobenzoatase and uPA. Suspensions of high-grade human astrocytomas were xenografted into pockets in host cerebral cortex for 1-7 days., Results: A class of guanidinobenzoatase positive cells was observed in the original human astrocytomas and in tumor masses formed in the implantation pocket and around blood vessels. Secondary foci containing guanidinobenzoatase positive cells formed around blood vessels and individual positive astrocytoma cells migrated on the glia limitans along parallel and intersecting nerve fiber fascicles and the corpus callosum. uPA and GFAP were colocalized with guanidinobenzoatase., Conclusion: The high-grade astrocytomas reestablish themselves and maintain their characteristics as a tissue although grafted as individual cells.

Because glioblastoma multiforme (GBM) frequently shows striking, glomeruloid microvascular proliferation (MVP), this tumor has become a strong candidate for anti-angiogenic therapy. However, the efficacy of anti-angiogenic treatment may rather be determined by the extent of classic angiogenesis with the formation of delicate microvascular sprouts. Therefore, this study differentially quantifies the microvascular changes in supratentorial diffuse astrocytic neoplasms by computerized image analysis of histological sections in which the microvessels were highlighted by a combined anti-collagen IV/MIB-1 staining. Four microvascular parameters (number, area, perimeter, diameter), the cellularity of the glial tissue, and the MIB-1 labeling index were assessed in biopsies of astrocytoma (A, n = 13), anaplastic astrocytoma (AA, n = 14), and GBM (n = 20), and in normal cerebral cortex (n = 7) and white matter (n = 7). In As and AAs, the microvascular parameters were not significantly different from each other, and the microvascular changes were generally limited compared with WM and CX. In contrast, in GBMs the microvascular parameters were highly variable, and their overall mean value was significantly increased compared with As and AAs (ranging from 1.3x for vessel diameter to 3.3x for vessel area). Our study indicates that not only glomeruloid MVP, but also classic angiogenesis, occurs mainly and only locally in GBMs. Thus, this study provides evidence that As and AAs are not good candidates for anti-angiogenic therapy. The efficacy of such therapy for GBMs awaits further evaluation.

The purpose of this study was to characterize regional blood flow (BF) in untreated cerebral gliomas (CG) using stable Xe-enhanced computed tomography (XeCT). XeCT of 38 patients with untreated CG were analyzed and compared with CT and magnetic resonance images (MRI) and histopathological findings. Individual averaged BF values for tumour in 29 high grade gliomas (HGGs) and 9 low grade gliomas (LGGs) were intermediate between averaged BF values for cortex and white matter in the non-tumour bearing hemisphere. All averaged BF values for cyst and central necrosis were very low. In 27 HGGs, BF in tumour was relatively high in ring-enhancement lesions on CT and MRI, but was low even in viable tumour centers showing no contrast enhancement. In the other 2 HGGs, BF was low in tumour center and relatively high in tumour periphery regardless of homogeneous enhancement. In 5 HGGs, averaged BF value of the cortex outside surrounding oedema was higher than that of cortex in the non-tumour bearing hemisphere. In LGGs, BF distribution in tumour was homogeneously low in 3 small-sized and heterogeneous in 6 large-sized lesions including moderately high and low BF regions. These differences in BF pattern between HGGs and LGGs on XeCT might be helpful in considering to some extent the histopathology of untreated cerebral glioma pre-operatively.

Reversible opening of the blood-brain barrier (BBB) has been used to increase delivery of chemotherapeutic agents into brain tumours, but it is complicated and requires general anaesthesia. Without affecting the normal BBB, and avoiding the complications of BBB modification by hyperosmotic solution, we tried an adequate minimal BBB disruption in brain tumours. Although the effect of BBB disruption on normal brain has been described, there are no reports of the effect of an impaired BBB on microcirculation. In this study, four patients underwent surgical resection of a glioblastoma multiforme (GM; n = 1), astrocytoma (n = 2), or metastatic brain tumour (n = 1). Epicerebral microcirculation was observed in the operative field. Serial fluorescein microangiograms of the tumour and peritumoural area were obtained before and after BBB disruption was introduced intra-operatively by retrograde infusion of mannitol introducing a catheter via the temporal superficial artery back to the carotid bifurcation. On the initial microangiogram, staining by the fluorescein dye was observed in the GM and metastatic tumour but not in the astrocytoma; no extravasation of fluorescein dye was observed in the peritumoural areas. After BBB disruption, fluorescein perfusion increased and extravasation of fluorescein dye from the venules was observed in the GM and the metastatic tumour and in the peritumoural area of both lesions; BBB disruption started from venules in the peritumoural area without affecting the normal brain. However, such effects were not observed in the astrocytomas after BBB disruption nor in normal brain tissue in any patient. It appears that the integrity of the BBB is less stable in the peritumoural area of GM and metastatic brain tumours than it is in astrocytomas or normal brain. Osmotic BBB disruption may offer a method for achieving global delivery of therapeutic agents to brain tumours and peritumoural areas.

The mean % ratio value of the number of endothelial cells with tubular bodies for the 6 cases of the glioblastomas proved to be 32.4% in the margin, which was about two times as high as that (15.7%) in the center of the tumors, showing a tendency for tubular bodies to be increased broadly in parallel with vascularization. In the 5 cases of astrocytoma, vascularization was less marked, and the mean % ratio was lower (14.8%) in all studied locations of the astrocytoma. It is suggested that the tubular bodies in the endothelial cells of microvessels of astrocytic tumors could increase in relation to microvessel proliferation and tumor malignancy.

Purpose: To determine the efficacy of superselective angio-CT in the diagnosis of astrocytoma., Methods: Nineteen patients with astrocytoma had superselective angio-CT before chemotherapeutic agents were administered via superselective intraarterial infusion. CT was performed after contrast material was delivered through a microcatheter, which had been advanced into the feeding arteries of the tumor. Superselective angio-CT scans were compared with digital subtraction angiograms, conventional contrast-enhanced CT scans, and contrast-enhanced T1-weighted MR images., Results: Superselective angio-CT scans depicted contrast enhancement of the tumor in all of the patients and the medullary veins of the tumors in 32% of the patients. Digital subtraction angiograms showed tumor stains in 68% of the patients and the medullary veins in only 5%. Conventional CT scans and MR images showed contrast enhancement of the tumor in 89% of the patients. Superselective angio-CT scans confirmed the proper position of the catheter tip for the infusion of a chemotherapeutic agent., Conclusions: Superselective angio-CT can be used to depict contrast enhancement of tumors and the vascular structures that are characteristic of astrocytomas.

Background: Microvessel density in tumors, a measure of angiogenesis, has been shown to be a prognostic indicator that correlates with an increased risk of metastasis in various epithelial cancers and with overall and relapse free survival in patients with breast cancer. Astrocytic brain tumors, particularly malignant astrocytomas, are recognized to be highly vascular tumors with potent angiogenic activity. However, the prognostic significance of microvessel density in these tumors is not known., Methods: Sections from formalin fixed paraffin embedded tumor tissue from 93 unselected adult patients with supratentorial astrocytic brain tumors were immunostained for factor VIII-related antigen in order to highlight microvessel endothelial cells. Microvessels were counted at 200x and 400x magnification. Microvessel density was graded as 1+ to 4+ on 1 low power field, without knowledge of clinical outcome. Microvessel count and microvessel grade were correlated with postoperative survival using the Cox proportional hazards regression model. The prognostic significance of microvessel count and grade were also compared with established prognostic indicators, including patient age, Karnofsky performance status, and tumor histology using multivariate analyses., Results: Both microvessel grade and microvessel count correlated significantly with postoperative survival by univariate analysis in both previously untreated and treated patients. Patients with tumors containing a microvessel Grade of 3+ or 4+ had significantly shorter survival time than patients with a microvessel Grade of 1+ or 2+ (P = 0.0022). Likewise, patients with microvessel counts of 70 or greater had significantly shorter survival than those with microvessel counts of fewer than 70 (P = 0.041). Patient age, Karnofsky performance status, tumor histology, and extent of resection were also correlated with survival by univariate analysis. Microvessel count was further shown to be an independent prognostic indicator by multivariate analyses. There were correlations between microvessel density and patient age and between microvessel density and astrocytic tumor grade., Conclusions: These findings support the importance of microvessel density as a prognostic indicator of postoperative survival of patients with astroglial brain tumors. Regional tumor heterogeneity may limit the use of these techniques for routine pathologic examination.

Eight patients with small gliomas (6 low-grade and 2 high-grade) localized in a single gyrus or less than 2 cm diameter were investigated using positron emission tomography and single photon emission computed tomography. All three tumors examined demonstrated hypermetabolism of amino acids. High-grade gliomas demonstrated hypermetabolism of glucose and high blood flow, but normal or low oxygen metabolism. High-grade gliomas also showed accumulation of 201Tl chloride and high or low accumulation of 123I-isopropyl iodoamphetamine. These indications allow preoperative diagnosis of the malignancy of small gliomas, which is important because small gliomas with high-grade malignancy need more extensive removal and adjuvant therapy.

A total of 22 surgical specimens, 16 astrocytomas with various malignancy, 3 brains adjacent to tumor and 3 brains with non-neoplastic lesion, was investigated immunohistochemically for the expression of thrombomodulin (TM). This membrane protein is localized on the vascular endothelium of nearly every human tissue and plays a crucial role in the maintenance of antithrombotic property of the endothelial cells. Although the normal cerebral vessels were negative for TM, the tumor vessels were positive for TM. The increased expression of TM was, however, demonstrated not only in glioblastomas but also in low-grade astrocytomas. Furthermore, the vessels in the brains adjacent to tumor and gliotic brains were also positive for TM. Those observations suggested that the tendency of intratumoral bleeding, which is rather characteristic of glioblastomas, is not simply explained by the altered expression of vascular endothelial TM. In two cases of glioblastoma, not only the blood vessels but also the tumor cells were positive. Considering the mitogenic activity of thrombin, a ligand for TM, the increased expression of TM might be related to the tumor neovascularization and also the tumor growth.

Two cases of cerebral pleomorphic xanthoastrocytomas (PXA-s) with prominent vascularity and desmoplastic changes occurring in young subjects are presented. The tumors displayed the marked pleomorphism characteristic of PXA-s and had variable cellularity. The cytoplasm of many tumor cells contained an abundance of lipid droplets. Most tumor cells were positive for glial fibrillary acidic protein. The unusual feature about these tumors was the presence of very large numbers of tiny blood vessels with variable thickness of their walls. In many areas the small vessels and the neoplastic astrocytes were in close proximity to each other, with capillaries adjacent to or protruding into tumor cell cytoplasm, reminiscent of the pattern seen in highly vascularized or "angiomatous" meningiomas. In other areas extensive fibrosis was seen. We feel that the latter, as in the cases of comparably vascular meningiomas, had its origin in congelation and secondary organization of plasma proteins that have exuded through leaky walls of newly formed blood vessels. These are the first reported cases of PXA with an angiogliomatous pattern.

Heretofore, the rCBF of brain tumours has been measured by the 133Xe clearance method, but the resolving power of this method is limited and flow values measured by this method correlate poorly with the anatomical structure. On the other hand, our xenon-enhanced method has several advantages over the conventional isotope method and enables us to evaluate rCBF with a resolving power of 4 mm. With this method, we evaluated rCBF in 15 brain tumour cases and obtained the following results: Mean rCBF value of the tumour is a little lower than that of grey matter and higher than that of white matter with oedematous change. The xenon-enhanced method enables us to distinguish the demarcation between the tumour area and the surrounding oedematous area and offers useful information for determining the extent of resection in surgery. Mean lambda value of the tumour which is not obtainable in vivo by radionuclide scanning, was 1.02 +/- 0.06 for gliomas and 0.72 +/- 0.09 for metastatic tumours.

The vascular changes associated with cerebral tumours are demonstrated angiographically and histologically.

A 48-year-old man was admitted with the sudden onset of symptoms of stroke caused by hemorrhage in an oligodendroglioma. Despite surgery and antiedema treatment, the patient died. Histological evaluation revealed an oligodendroglioma with calcified capillaries of the retiform type. To further investigate this phenomenon, a total of 160 gliomas were reviewed: 90 glioblastomas multiforme, 30 oligodendrogliomas, and 40 astrocytomas. Sufficient data were available for clinical evaluation in 100 cases. Of these, 5% (two oligodendrogliomas and three glioblastomas multiforme) were related to clinically significant hemorrhages. Of the remaining cases, microhemorrhages were found in 53.0% of the glioblastomas, in 56.7% of the oligodendrogliomas, and in 10.0% of the astrocytomas. In each case reviewed, the capillaries were assigned to one of three groups: axial, retiform, or glomeruloid. Statistical analysis revealed a significant association between hemorrhages and retiform capillaries in all three types of tumors, except that in oligodendrogliomas the statistical significance held true when calcification of the capillaries was also present. Glomeruloid-type capillaries were only weakly associated with hemorrhages, and no association was found for axial capillaries. A large-scale prospective study is necessary to more precisely assess the role of each of the three types of capillaries in hemorrhages of gliomas. Based on data available so far, patients with glial tumors with retiform capillaries, confirmed on biopsy, should be carefully monitored to exclude possible intratumoral hemorrhage.

In order to elucidate pathogenesis of perifocal edema in the human brain tumors, we observed the alteration of capillary permeability between the glioblastomas with remarkable edema (4 cases) and astrocytoma with slight edema (3 cases). Specimens were studied by conventional ultrathin section and freeze-fracture replica technique. In ultrathin sections of capillaries in glioblastomas, some of these cell junctions were tortuous, elongated, in fact, open. Other capillary abnormalities included endothelial hyperplasia with extensive vesicular formation, surface infolding of endothelial cells, irregularity of the basal lamina and the presence of a large collagen filled extracellular space. In freeze-fracture replicas of capillary endothelium, pinocytotic vesicles markedly increased and were an average fo 52 per micron. Tight junction in one area was seen as network of 6 strands composed of about 100A particles, but in the other areas as one or two strands. In ultrathin sections of astrocytoma, yet there were blood vessels appeared relatively normal. In freeze-fracture replicas, pinocytotic vesicles markedly increased and were an average of 34 per micron. Tight junction was seen as network of 7 strands. We concluded that fewer strands of the tight junction play an important role in increasing the permeability in the vessels of glioblastomas with severe perifocal edema, in addition to increasing the pinocytotic vesicles.