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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors review and discuss the basic concepts of cell kinetics as applied to brain tumors. Uncontrolled growth of a neoplasm represents an expanding tumor cell population. Four growth parameters characterize the behavior of a neoplastic population: cell cycle time, growth fraction, tumor doubling time, and cell loss. The concept of provisionally nondividing cells explains the disparity between cell cycle time and tumor doubling time. Human gliomas, like many non-neural solid tumors, contain variable proportions of actively proliferating and nonproliferating tumor cells; this ratio is expressed by the growth fraction. The major kinetic difference between glioblastomas and differentiated astrocytomas resides in their respective growth fractions, in all likelihood an inherent biological characteristic of each tumor. Glioblastoma proliferates at a rapid rate, and only a high rate of cell loss prevents this tumor from doubling its volume in less than 1 week. The selection of drugs and design of drug schedules for treatment of glioblastomas should be made with the knowledge that 60% to 70% of the cells in this tumor are resting (nonproliferating). If experience with other solid tumors is any guide, judicious selection and combined use of drugs according to kinetically sound schedules will produce more effective chemotherapy of brain tumors.
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PMID:Review of basic concepts of cell kinetics as applied to brain tumors. 108 66

This study investigated the secretion of a tumor necrosis factor (TNF) and lymphotoxin (LT) from lymphokine-activated killer (LAK) cells during co-culture with glioblastoma cell lines, autologous glioma cells, and other non-gliomatous tumor cell lines (K562 and Daudi). Cytokine secretion from peripheral blood mononuclear cells (PBMC) was also examined. The TNF activity of culture supernatants was measured by L cell cytotoxic assay, and a neutralization test using anti-TNF and/or anti-LT antibodies determined whether the cytotoxic activity was due to TNF or LT. The results show that LAK cells secrete both TNF and LT during monoculture and release increased amounts of TNF and LT with non-gliomatous tumor cell stimulation, but PBMC secrete only TNF with tumor cell stimulation. Glioblastoma or anaplastic astrocytoma cells, however, did not stimulate cytokine secretion from either LAK cells or PBMC. This indicates a discrepancy between the capability of LAK cells to lyse malignant glioma cells and cytokine secretion from LAK cells, and suggests that malignant glioma cells may produce some factors which inhibit cytokine secretion from LAK cells.
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PMID:Analysis of tumor necrosis factor and lymphotoxin secreted by incubation of lymphokine-activated killer cells with tumor cells. 137 61

Frozen tissue sections obtained from human glioblastomas, brain tumor metastases and normal brain were examined for the expression of molecules known to be involved in lymphocyte activation and/or adhesion and migration. The molecules studied included CD3, CD45R, UCHL-1 (CD45RO), lymphocyte function-associated antigen 1 (LFA-1) (CD11a, CD18), intercellular adhesion molecule 1 (ICAM-1) (CD54), 4B4 (CD29), CD44, CD2, and LFA-3 (CD58). CD3+ lymphocytes infiltrating human glioblastomas and brain tumor metastases expressed LFA-1 alpha and beta. Many cells were also UCHL-1+ whereas only a small percentage were CD45R+. CD2+ lymphocytes were also present. Tumor-infiltrating lymphocytes (TIL) were found to be negative for CD29, which was, however, expressed on intratumoral vessels in addition to vessels found in normal brain. Glioblastoma cells and intratumoral vessels expressed ICAM-1 whereas no ICAM-1 was found on TIL or on normal brain. Glioblastoma cells also expressed high levels of both CD44 and LFA-3 whereas TIL were negative for these antigens. CD44 was also expressed on certain regions of normal brain. Antibodies to LFA-1 alpha and -beta and ICAM-1 could significantly block the binding of lymphokine-activated killer (LAK) cells or TIL to human glioblastoma cells suggesting that these molecules play a role in the binding and subsequent migration of lymphocytes into brain tumor tissue.
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PMID:Activation and adhesion molecule expression on lymphoid infiltrates in human glioblastomas. 169 16

Tumor cells have been reported to exert inhibitory effects on the activation of T lymphocytes in vitro. We show that the IL-2-stimulated proliferation of a Th cell line is suppressed when the T cells are cocultured with human glioblastoma and melanoma cell lines. The use of two Th cell clones that differ in their responsiveness to growth-inhibition by transforming growth factor-beta (TGF-beta) and the analysis of tumor cell-derived supernatants as well as of TGF-beta 1/TGF-beta 2 gene expression allowed to distinguish two pathways of tumor-induced immunosuppression. Glioblastoma cells exert their immunosuppressive effects by producing biologically active TGF-beta 2, whereas the immunosuppressive state induced by melanoma cells is TGF-beta-independent and requires direct contact between tumor cell and T cell. The TGF-beta-dependent immunosuppression is down-regulated by various protease inhibitors and up-regulated by estradiol via modulation of the production of biologically active TGF-beta 2 by glioblastoma cells leaving total activatable TGF-beta 2 unaffected. No such modulation is functional for the TGF-beta-independent pathway of immunosuppression. We conclude that the production of active TGF-beta by tumor cells is regulated at a posttranslational level by the coordinated action of several proteolytic enzymes.
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PMID:Protease inhibitors interfere with the transforming growth factor-beta-dependent but not the transforming growth factor-beta-independent pathway of tumor cell-mediated immunosuppression. 172 72

This study demonstrates interleukin 6 (IL-6) production and release by human glioblastomas. Twenty glioblastoma cell lines were tested for IL-6 bioactivity using an IL-6-dependent cell line (7TD1). All of the lines tested with one exception (LN-229) constitutively released IL-6. A significant induction of IL-6 production and secretion was observed when LN-229 cells were treated with interleukin 1 beta (IL-1 beta) or tumor necrosis factor alpha. Various amounts of IL-6 mRNA were found in five of six cell lines tested. IL-6 mRNA was detected in line LN-229 only when the cells were treated with IL-1 beta or tumor necrosis factor alpha, confirming the bioassay data. Glioblastoma cells also produce IL-6 in vivo. (a) IL-6 activity was detected in 11 of 13 cerebrospinal fluids and five of five tumor cyst fluids. (b) IL-6 mRNA was found in four of four tumors. (c) Immunohistochemical analysis showed IL-6 within the tumor cells in 15 of 20 glioblastoma sections. In conclusion, biologically active IL-6 is released by almost all glioblastomas both in vitro and in vivo. The elevated levels of serum acute phase proteins and immune complexes found in glioblastoma patients may be the result of this secretion.
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PMID:Human glioblastoma cells release interleukin 6 in vivo and in vitro. 220 33

Authors have studied the ultrastructure of endothelial cells in the microvessels of malignant and benign gliomas and in particular, the numbers of tubular bodies (Weibel-Palade) in endothelial cells of glioma microvessels in related with blood vessel proliferation. Glioblastoma 6, astrocytoma grade II 1, oligodendroglioma 1 and 2 samples of non-tumor brain tissue were analyzed quantitatively using light and electron microscope with Karnovski fixative. All tissues were obtained from the center, the intermediate and the margin in each tumor tissue and just outside of the tumor at operation. 389 microvessels were examined in the total gliomas electronmicroscopically. Tubular body was first described by Weibel and Palade in the vascular endothelial cells of various organs in both man and animals. This is now considered to be an organelle specific to the endothelial cell, but its function is still unknown. Tubular body observed in the endothelial cells of the gliomas vessels consisted of a membrane-limited round, oval or elongated shaped intra cytoplasmic body (about 0.1-0.2 micron) which contained tubules of 150-200 A outer diameter. Tubular bodies were classified in the two types. One of them (mature type) was relatively electron dense to be more compact, the other (immature type) had relatively pale matrix. In the immature type they are located in close proximity to the Golgi complex or endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Tubular bodies (Weibel-Palade) in the endothelial cell of glioblastoma]. 240 97

Glioblastoma cells from three established lines were transplanted in oculo and in cerebrum to rat hosts. A very low dose of Cyclosporine A was found sufficient to allow graft survival whereas grafts in non-immunosuppressed animals did not survive. Moderate immunosuppression permitted long term graft survival without aggressive growth of glioblastoma cells, creating a protracted course during which neither cell rejection nor tumor proliferation occurred. A tumor reminiscent of a glioblastoma was only seen in one animal on high immunosuppression. Phenotypic changes such as the induction of glial fibrillary acidic protein (GFAP) production and an astrocytic morphology were observed in the cells growing in oculo but not in cerebrum. Vascularization was easily demonstrated with laminin immunofluorescence but the endothelial proliferation typical of glioblastomas was not seen.
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PMID:Prolonged survival and vascularization of xenografted human glioblastoma cells in the central nervous system of cyclosporine A treated rats. 246 19

The tumor viability of 28 gliomas after radiation therapy has been investigated by dynamic CT scan that estimated 4 parameters (Area, Peak, Time of Peak, and, Height of Plateau) from a time-density curve. Glioblastoma showed higher values of Area and Peak, whereas astrocytomas showed lower values when compared to those found in normal gray matter. After radiation therapy, the Area and Peak decreased and the Time to Peak was prolonged, suggesting a decrease in blood volume and blood flow in the tumor tissue. The increased Height of Plateau showed an increased permeability of the tumor-vessels. These results suggest that a dynamic CT scan provides a useful indicator of the change in tumor-viability after radiation therapy.
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PMID:[Decreased tumor viability of gliomas after radiation therapy, evaluated by dynamic CT scan]. 335 57

Tumor tissues of glioblastoma multiforme, astrocytoma and medulloblastoma, maintained up to 21--28 days by gelfoam organ culture technique, were examined by scanning electron microscopy (SEM). Glioblastoma multiform has irregular cell surface and many cytoplasmic folds. Astrocytoma has many fibrils. The fibrils have smooth surface and are coiling. Fibrils of piloid astrocytoma are smooth and cylindrical. The focal thickness of fibrils are associated with so-called Rosenthal fiber. Capillary of astrocytoma has irregular surface and marked tortuosity. Medulloblastoma is composed of non-fibrillated round tumor cells. The tumor cells touch each other with short cell processes. These findings seemed to correspond to the malignancy of original tumor. Comparative observation of medulloblastoma maintained by monolayer cell culture with one maintained by organ culture, using light microscopy and scanning electron microscopy, was done. And medulloblastoma in monolayer culture was proliferated to two types of cells. One is epitheloid cell with taper cell processes, and the other is stellate cell with fine processes. In most organ culture, feature of cells corresponded to those observed in original surgical material by light microscopy.
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PMID:[Scanning electron microscopy of human cultured gliomas (author's transl)]. 625 76

Eighty patients older than 65 years underwent craniotomy for primary or secondary brain tumors. Glioblastoma was the most common tumor, followed by metastatic carcinoma and meningioma. Three patients died within 30 days of surgery. Twenty-three patients showed development of postoperative systemic complications, of which pulmonary complications were most common. Thirty-seven (44%) of the patients showed significant improvement, but 13 (21%) became worse after surgery. Most brain tumors in elderly patients are operable. However, the surgical indications should be determined by the nature of the tumor and the condition of the individual patient. Preoperative and postoperative management must be more demanding if systemic complication are to be avoided.
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PMID:Brain tumors in the elderly. 724 29


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