Neoplastic Brain Tissue Research Articles

CNSC-08. TUMOUR-INFILTRATED CORTEX PARTICIPATES IN LARGE-SCALE COGNITIVE CIRCUITS

Abstract In neurosurgery, tumour-infiltrated cortex is generally assumed to be non-functional. While prior studies have suggested integration of tumour-infiltrated tissue in relatively local circuits responsible for language and motor function, it is unknown whether such tissue can participate in distributed networks important for higher-order cognitive abilities like executive function. We tested the hypothesis that diffuse low-grade gliomas integrate into large-scale cognitive circuits using intracranial electrocorticography and resting-state functional magnetic resonance imaging of four patients. To identify brain areas recruited for executive function, electrocorticography recordings were acquired from tumour-infiltrated tissue under three conditions: i) baseline (rest), ii) simple counting (1-20; “easy”), and iii) switch counting (1-a-2-b-3-c etc.; “hard”). In each patient, we observed significant task-based high gamma power modulations in tumour-infiltrated cortex in response to increasing cognitive effort (p < 0.05), implying preserved functionality of neoplastic tissue for complex tasks. Additionally, tumour locations corresponding to task-responsive electrodes exhibited functional connectivity patterns that significantly co-localised with canonical brain networks implicated in higher-order cognitive processing (p < 0.05). Finally, dorsal attention network connectivity in tumour-infiltrated cortex correlated with high gamma power elevations during increased cognitive demand (χ 2(1) = 5.14; p = 0.023), establishing a concordance between both techniques. Overall, this study contributes convergent evidence that tumour-infiltrated cortex can participate in large-scale neurocognitive circuits, prompting a reconsideration of traditional notions of neoplastic brain tissue.

Hexokinase 2 (HK2), the tumor promoter in glioma, is downregulated by miR-218/Bmi1 pathway.

In cancer, glycolysis driving enzymes and their regulating microRNAs are one of the key focus of oncology research lately. The glycolytic enzyme hexokinase 2 (HK2) is crucial for the Warburg effect in human glioma, the most common malignant brain tumor. In the present study, we studied the tumorigenic role of HK2 in glioma, and clarified the mechanism of miR-218 induced HK2 regulation in glioma development. The HK2 expression in patient derived glioma and non neoplastic brain tissue was quantified. The HK2 silenced U87 and U251 cell lines were assessed for their proliferation, migration and invasive potential in vitro, while the tumor forming potential of U87 cells was evaluated in vivo. The untreated cell lines served as control. The HK2 expression in (a) lentivirus-infected, miR-218 overexpressing and (b) shRNA mediated Bmi1 silenced U87 and U251 glioma cell lines were quantified. Luciferase reporter assay, qRT-PCR analysis and WB were employed as required. The HK2 expression was significantly increased in glioma tissues comparing with the non neoplastic brain tissues and was positively correlated with the glioma grade. Silencing HK2 in glioma cell lines significantly decreased their proliferation, migration, invasion and tumorigenic abilities. Although, overexpression of miR-218 significantly downregulated the HK2 expression, luciferase reporter assay failed to show HK2 as the direct target of miR-218. A direct correlation, however, was observed between HK2 and Bmi-1, the direct target of miR-218. Taken together, our findings confirmed the tumorigenic activity of HK2 in glioma, and the involvement of the miR218/Bmi1 pathway in the regulation of its expression.

B Cell Development Is Regulated By a-Synuclein, a Key Player In Parkinson's Disease

IntroductionSynucleins comprise a family of small proteins that were first identified in normal and neoplastic brain tissues. As a key component of the Lewy body, a-synuclein plays crucial roles in Parkinson disease and other dementias, and mediates neurotransmitter trafficking. The role of a-synuclein in hematopoiesis is largely unknown; however, in the hematopoietic system, a-synuclein is present in megakaryocytes, platelets, erythroid precursors and erythrocytes. In addition, it has also been detected by RT-PCR in monocytes, T-, B-, and NK-cells. Of interest, there is reduced expression of a-synuclein in the megakaryocytes of myeloproliferative neoplasm (MPN), but not normal reactive marrow or myelodysplastic syndrome, suggesting that a-synuclein could play an important role in the pathogenesis of MPN; while there is increased expression in blasts of megakaryoblastic leukemia. In this study, we utilized a-synuclein-/- mice as a model to investigate the role of a-synuclein in hematopoiesis. We identified an unexpected role of a-synuclein in B cell development and maturation. MethodsAge- and sex-matched a-synuclein-/- mice and wild type mice (6-week-old; N=10 each group) were purchased from The Jackson Laboratory (Bar Harbor, ME). Bone marrow cells, splenocytes, and lymph nodes were harvested and flow cytometry analysis performed looking at B cell markers. Histological examination of bone marrow, lymph nodes, and spleen were also performed. ResultsB220lo immature B cells were comparable between WT and KO mice (WT: 2.62±0.30% vs. KO: 3.55±0.67%, Figure1 Aand Table 1); similarly, pre-B cells identified as B220loCD43+ population were comparable between the two groups (Figure 1B). However, when IgD was applied to separate B220hi population into IgD+ and IgD- subsets, circulating B cells (B220hiIgD+ subset), were significantly reduced by 5-fold in KO mice compared to WT (KO: 0.12±0.05% vs. WT: 0.59±0.37%, p=0.02), whereas B220hiIgD- subset representing transitional B cells was similar between WT and KO mice (WT: 1.54±0.22% vs. KO: 2.09±0.70%, Figure1 A and Table 1). Therefore, although early B cell development is not affected, the number of mature B cells in bone marrow is reduced in a-synuclein deficient mice. [Display omitted] Table 1Summary of B cell development in a-synuclein-/- miceWT (n=5)KO (n=5)p valueBone marrowImmature B cells (%)(B220lo)2.62±0.303.55±0.670.30Transitional B cells (%)(B220hiIgD-)1.54±0.222.09±0.700.22Circulating B cells (%)(B220hiIgD+)0.59±0.370.12±0.050.02Spleen B220 + cells (%)14.0±1.95.5±1.60.00006Lymph node B220+ cells (%)11.5±2.816.1±6.00.16In spleen, there was a marked reduction in the number of B cells compared to WT: 5.5+1.6% vs. 14.0+1.9%, respectively (Figure 2A and Table 1). The absolute number of B cells was more drastically reduced in KO mice as the total number of splenocytes was only half of that in WT (Figure 2B and data not shown). Histologically, white pulp areas in KO mice were disorganized compared to WT mice (Figure 2B). These results collectively show that the number and distribution of B cells in spleen is regulated by a-synuclein. [Display omitted] On the other hand, though the percentage of B cells in lymph nodes was comparable between WT and KO mice, the absolute number of B cells was lower in KO mice and morphologically the lymph nodes from KO mice were smaller than those from WT mice (Table 1, Figure 3A and data not shown). Normal lymph node cortical/ follicular architecture was missing in KO mice compared to WT controls (Figure 3B). The number of follicles in KO mice was 5-fold lower than that WT controls (WT: 5±0.2/HPF vs. KO: 1±0.3/HPF, p=0.001). [Display omitted] ConclusionOur data shows that the number and localization of mature B cells in spleen and lymph nodes is in part regulated by a-synuclein. This is the first report to implicate an important role of a-synuclein in B cell development. The mechanism of a-synuclein regulation in B cells is under investigation. Disclosures:No relevant conflicts of interest to declare.

Sox11 expression in astrocytic gliomas: correlation with nestin/c-Met/IDH1-R132H expression phenotypes, p-Stat-3 and survival

Background:Sox11 is a transcription factor expressed in foetal and neoplastic brain tissue, including gliomas. It has been shown to suppress the tumourigenicity of glioma stem cells in vivo, thereby being hypothesised to function as a tumour suppressor.Methods:We investigated the expression of Sox11 in 132 diffuse astrocytomas in relation to the regulator cell marker nestin, c-Met and IDH1-R132H, which have shown to be differentially expressed among the molecular subgroups of malignant gliomas, as well as to an inducer of astrocytic differentiation, that is, signal transducer and activator of transcription (p-STAT-3), clinicopathological features and survival.Results:Sox11 immunoreactivity was identified in all tumours irrespective of grade, but being correlated with p-STAT-3. Three out of seven cases showed partial Sox11 promoter methylation. In >50% of our cases neoplastic cells coexpressed Sox11 and nestin, a finding further confirmed in primary glioblastoma cell cultures. Furthermore, nestin, c-Met and IDH1-R132H expression differed among grade categories. Cluster analysis identified four groups of patients according to c-Met, nestin and IDH1-R132H expression. The c-Met/nestin high-expressor group displayed a higher Sox11 expression. Sox11 expression was an indicator of favourable prognosis in glioblastomas, which remained in multivariate analysis and validated in an independent set of 72 cases. The c-Met/nestin high-expressor group was marginally with shorter survival in univariate analysis.Conclusions:We highlight the importance of Sox11 expression as a favourable prognosticator in glioblastomas. c-Met/nestin/IDH1-R132H expression phenotypes recapitulate the molecular subgroups of malignant glioma.

Confocal Laser Endomicroscopy for Diagnosis and Histomorphologic Imaging of Brain Tumors In Vivo

Early detection and evaluation of brain tumors during surgery is crucial for accurate resection. Currently cryosections during surgery are regularly performed. Confocal laser endomicroscopy (CLE) is a novel technique permitting in vivo histologic imaging with miniaturized endoscopic probes at excellent resolution. Aim of the current study was to evaluate CLE for in vivo diagnosis in different types and models of intracranial neoplasia. In vivo histomorphology of healthy brains and two different C6 glioma cell line allografts was evaluated in rats. One cell line expressed EYFP, the other cell line was used for staining with fluorescent dyes (fluorescein, acriflavine, FITC-dextran and Indocyanine green). To evaluate future application in patients, fresh surgical resection specimen of human intracranial tumors (n = 15) were examined (glioblastoma multiforme, meningioma, craniopharyngioma, acoustic neurinoma, brain metastasis, medulloblastoma, epidermoid tumor). Healthy brain tissue adjacent to the samples served as control. CLE yielded high-quality histomorphology of normal brain tissue and tumors. Different fluorescent agents revealed distinct aspects of tissue and cell structure (nuclear pattern, axonal pathways, hemorrhages). CLE discrimination of neoplastic from healthy brain tissue was easy to perform based on tissue and cellular architecture and resemblance with histopathology was excellent. Confocal laser endomicroscopy allows immediate in vivo imaging of normal and neoplastic brain tissue at high resolution. The technology might be transferred to scientific and clinical application in neurosurgery and neuropathology. It may become helpful to screen for tumor free margins and to improve the surgical resection of malignant brain tumors, and opens the door to in vivo molecular imaging of tumors and other neurologic disorders.

Quantitative fluorescence in intracranial tumor: implications for ALA-induced PpIX as an intraoperative biomarker

Accurate discrimination between tumor and normal tissue is crucial for optimal tumor resection. Qualitative fluorescence of protoporphyrin IX (PpIX), synthesized endogenously following δ-aminolevulinic acid (ALA) administration, has been used for this purpose in high-grade glioma (HGG). The authors show that diagnostically significant but visually imperceptible concentrations of PpIX can be quantitatively measured in vivo and used to discriminate normal from neoplastic brain tissue across a range of tumor histologies. The authors studied 14 patients with diagnoses of low-grade glioma (LGG), HGG, meningioma, and metastasis under an institutional review board-approved protocol for fluorescence-guided resection. The primary aim of the study was to compare the diagnostic capabilities of a highly sensitive, spectrally resolved quantitative fluorescence approach to conventional fluorescence imaging for detection of neoplastic tissue in vivo. A significant difference in the quantitative measurements of PpIX concentration occurred in all tumor groups compared with normal brain tissue. Receiver operating characteristic (ROC) curve analysis of PpIX concentration as a diagnostic variable for detection of neoplastic tissue yielded a classification efficiency of 87% (AUC = 0.95, specificity = 92%, sensitivity = 84%) compared with 66% (AUC = 0.73, specificity = 100%, sensitivity = 47%) for conventional fluorescence imaging (p < 0.0001). More than 81% (57 of 70) of the quantitative fluorescence measurements that were below the threshold of the surgeon's visual perception were classified correctly in an analysis of all tumors. These findings are clinically profound because they demonstrate that ALA-induced PpIX is a targeting biomarker for a variety of intracranial tumors beyond HGGs. This study is the first to measure quantitative ALA-induced PpIX concentrations in vivo, and the results have broad implications for guidance during resection of intracranial tumors.

Alpha‐ and beta‐synucleins are new diagnostic tools for acute erythroid leukemia and acute megakaryoblastic leukemia

α-Synuclein is a key component of the Lewy body, a large globular protein complex that forms in the nervous system of patients with Parkinson disease and other dementias [1-3]. Since α-synuclein also occurs in megakaryocytic and erythroid lineages [4-7], we wondered what role synucleins had in the hematopoietic system. Therefore, we studied the expression of α-, β-, and γ-synucleins in a comprehensive panel of patient bone marrows and leukemic cell lines. We observed under expression of α-synuclein in the megakaryocytes of myeloproliferative neoplasm (MPN), but not normal reactive marrow (NRM) or myelodysplastic syndrome (MDS). Conversely, we observed over expression of β-synuclein in the blasts of megakaryoblastic leukemias (MegL), but not acute myeloid leukemia (AML) or erythroleukemia (EryL), suggesting that α- and β-synucleins could be useful adjunct markers for the early detection of MDS and the differential diagnosis of EryL and MegL from other AMLs.

Towards Drug Discovery for Brain Tumours: Interaction of Kinins and Tumours at the Blood Brain Barrier Interface

Cancers of the brain are intrinsically more complicated to treat than systemic malignancies due to the unique anatomical features of the brain. The blood-brain barrier prevents chemotherapeutic agents from reaching brain neoplasms, and angiogenesis occurs as the metabolic needs of the tumour increase, thus further complicating treatment. The newly formed blood vessels form the blood-tumour barrier and are distinct from the blood-brain barrier in that they are more permeable. Being more permeable, these abnormal blood vessels lead to the formation of peri-tumoural edema, which is the cause of much morbidity and mortality associated with central nervous system neoplasms. While the cause of the increased permeability is unclear, kinins have been implicated in regulating the permeability of normal vasculature. Kinins are also known to exert many inflammatory actions affecting both normal and angiogenic blood vessels, as well as tumour cells. The vasodilatory and vascular permeabilizing effects of kinins, and particularly bradykinin and substance P, have been investigated with regard to delivery of chemotherapeutic agents to neoplastic brain tissue through both vascular barriers. In contrast, kinin receptor antagonists have been found to exert effects on tumour cells that result in decreased angiogenesis, tumour cell motility and growth. Thus, many recent patents describe kinin activity on brain vasculature, which may play an integral role in the development of treatments for malignancies in the central nervous system through amelioration of angiogenesis. In conjunction, patents that discuss the ability of kinins to decrease tumour cell migration and proliferation demonstrate that kinins may offer novel approaches to brain tumour therapy in the future.

Evaluation of intracranial space-occupying lesion with Tc99m-glucoheptonate brain single photon emission computed tomography in treatment-naïve patients

Glucoheptonate is a glucose analog with strong affinity for neoplastic brain tissues. Though extensively used as a tracer for detection of brain tumor recurrence, it's utility for characterization of intracranial lesions as neoplastic or otherwise has not been evaluated in treatment-naïve patients. The study was conducted to determine if glucoheptonate has sufficient specificity for neoplastic lesions of brain so that it can be utilized as a single photon emission computed tomography (SPECT)-tracer for differentiating neoplastic intracranial lesions from non-neoplastic ones in treatment-naïve patients. A cross-sectional analysis of treatment-naïve patients with intracranial space-occupying lesion done in a tertiary care hospital. Fifty-four consecutive patients with clinical and radiological features of space-occupying lesion were included in this study. Glucoheptonate brain SPECT was performed before any definitive therapeutic intervention. Histopathological verification of diagnosis was obtained in all cases. Descriptive statistics and student's 't' test. Increased glucoheptonate uptake over the site of radiological lesion was noted in 41 patients and no uptake was noticed in 13 patients. Histopathology of 12 out of the 13 glucoheptonate non-avid lesions turned out to be non-neoplastic lesion; however, one lesion was reported as a Grade-2 astrocytoma. Histology from all the glucoheptonate concentrating lesions was of mitotic pathology. The sensitivity, specificity and accuracy of glucoheptonate for neoplastic lesion was 97.6%, 100% and 98.1%. Glucoheptonate has high degree of specificity for neoplastic tissues of brain and may be used as a tracer for SPECT study to differentiate neoplastic intracranial lesions from non-neoplastic ones.

Aminothiols in human brain tumors

Aminothiols are sulfur-containing amino acids involved in methionine metabolism. Changes in their levels play negative roles in the genesis of many diseases. These mechanisms involve direct toxicity, either on glutamate neurotransmitter receptors or cerebrovascular endothelium, and have an indirect inhibitory effect on transmethylation reactions. Oxidative stress and excitotoxicity are factors that may rise as a consequence of increased homocysteine levels in brain tissues. We discovered new information concerning concentrations of the main aminothiols in human neoplastic brain tissues. The cytosolic fractions of 73 tissue samples from human brain tumors were used for the determination of total homocysteine, total cysteine and methionine levels. Gas chromatography with flame ionization detection after reduction of disulfide bonds was the method used. Average concentrations of the aminothiols examined were as follows: total homocysteine, 0.58-1.51 nmol/mg; methionine, 1.16-2.07 nmol/mg; and total cysteine 5.08-7.82 nmol/mg of total protein. Significantly higher levels of total homocysteine were found in pituitary adenoma and glioblastoma multiforme compared with other types of tumors. Methionine and cysteine concentrations did not differ significantly according to diagnosis. This is the first work concerning the concentrations of aminothiols in brain tissues. The results obtained indicate the metabolic pathways that are involved in tumor formation and/or its progress, including the toxic effects of homocysteine.

Expression of MMP2, MMP9 and MMP3 in Breast Cancer Brain Metastasis in a Rat Model

In order to study the expression of MMP2, MMP3 and MMP9 in breast cancer brain metastasis, we used a syngeneic rat model of distant metastasis of ENU1564, a carcinogen-induced mammary adenocarcinoma cell line. At six weeks post inoculation we observed development of micro-metastasis in the brain. Immunohistochemistry and Western Blotting analyses showed that MMP-2, -3 and -9 proteins expressions are consistently significantly higher in neoplastic brain tissue compared to normal brain tissue. These results were confirmed by RT-PCR. In situ zymography revealed gelatinase activity within the brain metastasis. Gel zymography showed increase in MMP2 and MMP3 activity in brain metastasis. Furthermore, we were able to significantly decrease the development of breast cancer brain metastasis in animals by treatment with PD 166793, a selective synthetic MMP inhibitor. In addition, PD 166793 decreased the in vitro invasive cell behavior of ENU1546. Together our results suggest that MMP-2, -3 and -9 may be involved in the process of metastasis of breast cancer to the brain.

High-molecular-weight tropomyosins localize to the contractile rings of dividing CNS cells but are absent from malignant pediatric and adult CNS tumors.

Tropomyosin has been implicated in the control of actin filament dynamics during cell migration, morphogenesis, and cytokinesis. In order to gain insight into the role of tropomyosins in cell division, we examined their expression in developing and neoplastic brain tissue. We found that the high-molecular-weight tropomyosins are downregulated at birth, which correlates with glial cell differentiation and withdrawal of most cells from the cell cycle. Expression of these isoforms was restricted to proliferative areas in the embryonic brain and was absent from the adult, where the majority of cells are quiescent. However, they were induced under conditions where glial cells became proliferative in response to injury. During cytokinesis, these tropomyosin isoforms were associated with the contractile ring. We also investigated tropomyosin expression in neoplastic CNS tissues. Low-grade astrocytic tumors expressed high-molecular-weight tropomyosins, while highly malignant CNS tumors of diverse origin did not (P </= 0.001). Furthermore, high-molecular-weight tropomyosins were absent from the contractile ring in highly malignant astrocytoma cells. Our findings suggest a role for high-molecular-weight tropomyosins in astrocyte cytokinesis, although highly malignant CNS tumors are still able to undergo cell division in their absence. Additionally, the correlation between high-molecular-weight tropomyosin expression and tumor grade suggests that tropomyosins are potentially useful as indicators of CNS tumor grade.

Characterization of a novel oncofetal cell surface glycoprotein

The principal reason for the poor prognosis associated with malignant astrocytomas is recurrence as a result of invasion of surrounding brain parenchyma by tumour cells. As part of an investigation into the mechanisms of astrocytoma invasion, we raised monoclonal antibodies (Mab) against cell surface proteins expressed by an anaplastic astrocytoma cell line (G-CCM). One of the antibodies (MQ1 Mab) recognizes a novel cell surface glycoprotein (MQ1) with a molecular weight of 200 kDa. N-terminal sequencing revealed no sequence homology with any known mammalian protein. In vitro MQ1 protein expression was found on astrocytomas and fetal astrocytes, with the level of expression increasing with astrocytoma malignancy and decreasing with fetal astrocyte maturity. Immunohistochemistry on histologically normal and neoplastic brain tissue demonstrated that MQ1 protein expression is restricted to astrocytomas (n = 52). Other primary brain tumours tested and normal brain cells were MQ1 negative. A G-CCM cDNA expression library was synthesized and screened with the MQ1 antibody. Two positive clones were isolated and sequencing data demonstrated that both have a high degree of homology with Jagged1, a human Notch ligand. Subsequent protein studies indicate that the MQ1 protein has homology with, but is not identical to Jagged1. Knocking out MQ1 protein expression with antisense oligonucleotides induced apoptosis in the G-CCM cell line.

In vitro magnetic resonance spectroscopy of healthy and neoplastic brain tissues

In this study an in vitro Magnetic Resonance Spectroscopic characterization of water soluble metabolites and the lipid fraction obtained from 31 tumors (14 glioblastomas, 3 anaplastic astrocitomas, 2 anaplastic oligodendrogliomas, 2 oligodendrogliomas and 10 meningiomas) is reported. The 1H MR spectrum of normal brain tissue is also shown, it is characterized by a low Cho/Cr signal intensity ratio and an intense NAA resonance. The regional metabolic heterogeneity of glioblastomas is documented. For these tumors, specific molecular composition by MRS cannot be defined. Oligodendrogliomas and anaplastic oligodendrogliomas showed typical Cho/Cr and Ala/Cr metabolite ratios. The degree of histological endothelial proliferation of the malignant astrocitomas and oligodendrogliomas was correlated to the presence of Cholesteryl esters in the 13C Magnetic Resonance spectrum of the lipid fraction obtained from these tumors. Meningiomas are mainly characterized by high Cho/Cr and Ala/Cr ratios.

Human herpesvirus‐6: A survey of presence and distribution of genomic sequences in normal brain and neuroglial tumors

In an attempt to study the frequency and distribution of human herpesvirus-6 (HHV-6) infection both in normal and neoplastic brain tissues in vivo, polymerase chain reaction was used to look for HHV-6 genomes: 1) in samples, obtained at necropsy, from different regions of the brain of immunocompetent adult subjects and of patients who died of AIDS; 2) in the surgical biopsies of a well-characterized series of primary brain tumors of neuroglial origin. HHV-6-specific sequences were identified in six of nine brain samples from immunocompetent subjects, and in four of seven brain samples from AIDS patients. Viral sequences were identified in the specimens derived either from the grey (frontal cortex and basal ganglia) or from the periventricular white matter. HHV-6 DNA was found only in 6 of the 37 primary brain tumor biopsies examined. This study provides for the first time molecular evidence of a wide distribution of HHV-6 infection in the brain tissues of a high proportion of subjects, both in normal and in impaired immunity. In this large series of tumor biopsies the presence of HHV-6 genomic sequences is a rare phenomenon, arguing against a major role of this herpesvirus in the pathogenesis of primary brain tumors of neuroglial origin in immunocompetent subjects.

Gliosis specimens contain clonal cytogenetic abnormalities

The relevance of sex chromosome aneusomy and trisomy 7 in neoplastic brain tissue is controversial. For better understanding of the relative importance of these anomalies, we made a conventional cytogenetic study of cells from tissue obtained from patients who underwent partial cerebral resection for a seizure disorder. Each specimen exhibited “gliosis,” but none contained histologically identifiable tumor cells. Sixty-six specimens were analyzed by routine cytogenetic methods. Nonclonal abnormalities were observed in 11.6% of the cells (86% of cases) analyzed. In 11 cases, however, simple clonal karyotypes were observed. Of these cases, six involved loss of a Y chromosome and three involved loss of an X chromosome. Among the cases with loss of an X chromosome, two exhibited multiple abnormal clones. One of these cases had trisomy 7 as well as trisomy 18, and another had a supernumerary psu dic(15)(q13). The supernumerary chromosome was constitutional. One patient had possible Klinefelter syndrome. An additional case had a clonal del(10)(q23) that may have resulted from a hereditary fragile site. We conclude that although some of the apparently acquired clonal and nonclonal abnormalities may be due to a consistent in vitro artifact, it is probable that they are present in the brain tissue itself. Whatever the cause, caution should be used in interpretating cytogenetic abnormalities observed in brain tumor specimens.

Transferrin receptor in normal and neoplastic brain tissue: implications for brain-tumor immunotherapy

The distribution of transferrin receptor (TfR) in normal human brain-tissue obtained at autopsy and in brain-tumor biopsy specimens from 27 patients was determined by immunohistochemistry using two specific murine monoclonal antibodies against human TfR. The tumors studied included 10 glioblastomas multiforme (GBM's), nine other glial tumors, and eight meningiomas. In normal brain, TfR was detected primarily in endothelial cells; rare glial cells also contained immunoreactive product. All tumors contained TfR-positive cells, although the intensity (number of cells stained) and pattern (focal vs. diffuse) of staining varied with the histopathological type of the tumor. Among gliomas, the most intense staining was seen in GBM's, especially in areas of pseudopalisading where virtually all cells were stained. A rough correlation between tumor grade, number of positively stained cells, and staining pattern was seen in the other astrocytic tumors. By contrast, all meningiomas demonstrated an identical and characteristic focal staining pattern. Considering the differential immunostaining for TfR between normal and neoplastic tissue, the authors conclude that TfR may be an appropriate target for monoclonal antibody-directed brain-tumor immunotherapy, especially in more malignant tumors such as GBM's.

Synthesis of plasma proteins in fetal, adult, and neoplastic human brain tissue

The synthesis of plasma proteins directed by mRNA from human brain tissues was studied by combining in vitro or in ovo translation of mRNAs with crossed immunoelectrophoresis of the mRNA-directed labeled polypeptides, followed by autoradiography of the washed plates. Poly(A)-containing mRNA was prepared from different developmental stages of fetal and postnatal human brain and also from primary glioblastomas and meningiomas. Several plasma protein-like polypeptides were identified in the autoradiographs by their migration coordinates in the two-dimensional gels, compared with immunoprecipitates formed by mature, unlabeled, stainable proteins. These included polypeptides migrating like Gc globulin, haptoglobin, fibrinogen, α-fetoprotein, transferrin, cholinesterase, and α 2-macroglobulin; other, yet unidentified plasma proteins, were also observed. In general, the synthesis of these plasma proteins appeared to be more pronounced in fetal and neoplastic brain tissues than in postnatal tissues. However, clear immunoprecipitates for some of these plasma proteins could also be detected in products directed by mRNA from particular regions of mature, normal brains, indicating that some synthesis of plasma proteins takes place in the human brain even as late as 40 years of age. mRNAs for several proteins were also identified in samples of neoplastic brain. mRNA for transferrin was identified in normal fetal and adult brain but not in either the glioblastomas or meningiomas studied. Microinjected Xenopus oocytes, in which post-translational processing occurs as well, were also used to translate fetal brain mRNA. Several plasma proteins could be detected in the translation products which were induced and stored in the oocytes. These included hemopexin, which could not be detected in the in vitro system. Others, such as cholinesterease, were found to be secreted by the oocytes. These findings indicate that different cell types in the human brain may produce and either store or secrete particular plasma proteins at defined stages in their development.

Effects at the periphery of the laser lesion in human brain and its tumors after CO2, Nd:YAG, and CO2 high-peak pulsed radiation.

The histological changes in various tissues irradiated with lasers are well known. Our own previous observations with the optical microscope confirm those already reported in the laser literature. If tissue is treated with various laser sources, the results are similar, with the characteristic three layers from the outside toward the inside of carbonization, coagulative necrosis, and edema. Otherwise, only the shapes and sizes of the lesions differ, with craters of different depths. In this paper, we report an ultrastructural study of the changes occurring in the periphery of the laser lesions in both normal human brain and neoplastic tissues (gliomas and meningiomas). Continuous-wave CO2 and Nd:YAG lasers were used at different exposure times and powers and the effects of high-peak pulsed CO2 laser radiation has also been investigated. The study, performed during neurosurgical procedures was mostly focused on microcirculation at 1.5-3 mm outside the area of coagulative necrosis, at the level of the edema zone. Only lesions of the blood brain barrier are produced in normal brain by CO2 radiation (power ranging from 40 to 80 W; exposure time from 3 to 10 seconds). The same results were achieved by Nd:YAG radiation of short duration (3 seconds) regardless of the power used (40 and 80 W). Long-duration Nd:YAG radiation (10 sec; power: 40-80 W) produces endoluminal phenomena leading to the complete occlusion of the capillaries. In neoplastic brain tissues, microcirculation does not seem to be impaired by CO2 radiation. More marked lesions are produced in tumors even after Nd:YAG short-time radiation. Endoluminal obliteration is observed in meningiomas and perivascular hemorrhage occurs in highly vascularized gliomas. According to these results, the risk of delayed post-operative hemorrhages, noticed in some patients with glioblastoma operated on by Nd:YAG lasers, suggests that residual tumor in the cavity should be treated by CO2 laser because of its minimal damage of microcirculation.

Enhanced DNA synthesis of human glial cells exposed to human leukocyte products

DNA synthesis was studied in primary glial cell cultures derived from adult human non-neoplastic and neoplastic brain tissues. Enhanced DNA synthesis occurred in 5 5 non-neoplastic astrocyte, one oligodendroglioma, and 2 5 astrocytoma cultures after exposure to medium containing 1.25–12.5% supernatant fluid (SF) from insoluble concanavalin A (Con A) stimulated unseparated or T lymphocyte-enriched human mononuclear leukocytes (MNL). Analyses of SF indicated that the presence of platelet-derived growth factor (PDGF) could not account for glial cell stimulation, and exposure to semi-purified interleukin-2 (IL-2) in amounts comparable to those in SF from Con A-stimulated MNL had no effect on glial cells. These data indicate that non-neoplastic astrocytes and other human glial cells are stimulated by products of human MNL.