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

The mechanism and the clinical significance of calcium deposits in glioma have been still obscure. Excluding pinealomas, 221 histologically proven intracranial gliomas were studied. The presence of roentgenological calcification in 27 of the authers' series represented an incidence of 12 percent. The incidence of roentgenological calcification in various types of glioma were as follows: astrocytoma grades 1 & 2-15%, astrocytoma grades 3 & 4-7%, medulloblastoma-5%, ependymoma-17%, oligodendrogioma-60%, and choroid plexus papilloma-25%. There was no characteristic relationship between the incidence of calcification and the age distribution. One exception was noted that in astrocytoma grades 1 & 2 the incidence of roentgenological calcification tended to be higher in younger patients than in older patients. The percentage of calcified tumors in both sexes was the same. In astrocytoma and ependymoma the incidence of roentgenological calcification was far greater in the supratentorial tumor than in the infratentorial tumor. According to their roentgenological appearance, calcified tumors were separated into four groups, but any specific appearance could not be claimed for any particular type of glial tumors. Only in astrocytoma both the duration of symptoms and the postoperative survival time of the calcified cases were longer than those of the uncalcified. But in other types of glioma there were no significant differences in the postoperative survival time between the calcified cases and the uncalcified ones. In 5 cases of astrocytomas the calcium deposits did not exist on preoperative radiographs, which were found postoperatively after chemotherapy and/or radiotherapy. In conclusion, it is not the histological type but the duration of the clinical course that plays more important role in calcification of gliomas.
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PMID:[Calcification in gliomas: first report with special reference to roentgenological calcification (author's transl)]. 123 29

All primary intracranial neoplasms diagnosed between 1935 and 1964, inclusive, in the well-defined populations of children under age 15 residing in the state of Connecticut and the city of Rochester, Minnesota, formed the basis for this study. The tumors occurring in this group were characterized by histologic type and by the patient's sex and the age when the tumor occurred. In Connecticut, over the 30-year period, a primary intracranial neoplasm was diagnosed in 380 patients in a mean population of 582,286 children, yielding an average annual incidence rate of 2.17 cases/100,000 population per year. Of the microscopically confirmed tumors, the most common, in order, were medulloblastoma (24.2%), astrocytoma (20.6%), glioblastoma (20.3%), ependymoma (6.5%), craniopharyngioma (5.6%) and meningioma (4.6%). These figures contrast sharply with the corresponding frequency of these tumors in the adult Connecticut population. In Rochester during the same years, 12 primary intracranial neoplasms occurred in a mean population of 7,981 children, yielding an average annual incidence rate of 5.01 cases/100,000 population per year.
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PMID:The epidemiology of primary intracranial neoplasms of childhood. A population study. 124 98

The authors have routinely inserted a ventriculoperitoneal shunt in all patients with a posterior fossa tumor and hydrocephalus some 7-10 days prior to craniotomy. Forty-one patients with medulloblastoma were treated in this fashion and of these, four metastasized through the shunt and died of systemic metastases without evidence of recurrent tumor in their central nervous system. A millipore filter which can be incorporated in the shunt has been used by the authors during the past 18 months in an effort to prevent metastatic spread through the shunt.
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PMID:Metastasis via ventriculoperitoneal shunt in patients with medulloblastoma. 126 15

In an audit of 17,417 necropsies from 1939 to 1989 at the Royal Women's Hospital, Melbourne, Victoria, 46 congenital tumors comprising 24 teratomas, 8 vascular tumors, 6 neuroblastomas, three rhabdomyomas, two mesoblastic nephromas, one thyroid adenoma, one hepatic adenoma and one cerebellar medulloblastoma were found. The teratomas were generally large tumors and, because of their size and location, incompatible with extrauterine life. Ten teratomas were associated with polyhydramnios, three with obstructed labour, five of the fetuses were hydropic and four had malformations at sites distant to the tumor. Twenty teratomas occurred in stillbirths, half of whom were macerated. The vascular tumors were associated with polyhydramnios in three cases and hydrops fetalis in two. The neuroblastomas were all incidental findings. Four were intra-adrenal, one was an adrenal tumor which had metastasized to the liver and the remaining case was a small paravertebral lesion. Two of the three rhabdomyomas were multiple and one of these occurred in a case of tuberous sclerosis. One of the mesoblastic nephromas occurred in a hydropic fetus who had the Arnold-Chiari malformation. The thyroid and hepatic adenomas were small incidental lesions. The cerebellar medulloblastoma had led to marked hydrocephalus. Congenital tumors have different incidence, presentation and behaviour than those in childhood or adult life. The association of congenital tumors with congenital malformations and hydrops fetalis should always be remembered.
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PMID:Survey of congenital tumors in perinatal necropsies. 128 65

Eleven pediatric brain tumors were studied for the histone H3, Vimentin and MYC gene expression. H3, an S phase cell cycle-related gene (ccr), was found prevalently expressed in tumors with a high mitotic index (MI). Vimentin gene, which contributes to maintaining the cell structure but is also demonstrated to be an early responder gene to growth stimulation was found variously expressed. The different expression of Vimentin gene in the examined samples suggests the active proliferation of the tumor cells. Analysis of MYC gene expression was found increased only in a mesenchymal chondrosarcoma while in other samples MYC mRNA was undetectable. Medulloblastoma, chondrosarcoma, and choroid plexus carcinoma have high S phase H3 gene expression associated with a high MI. Differently an astrocytoma shows a low MI associated with high H3 gene expression. This first preliminary report of H3, Vimentin and MYC gene expression in brain tumors demonstrates that malignant cells are characterized by a different gene expression and different growth potentials.
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PMID:Expression of histone H3 cell cycle-related gene, vimentin and MYC genes in pediatric brain tumors. A preliminary analysis showing the different malignant cell growth potential. 131

Despite aggressive therapy, many nervous system neoplasms, including malignant gliomas, medulloblastomas, malignant meningiomas, and neurofibrosarcomas, maintain high mortality rates. The authors recently utilized a thymidine kinase-negative herpes simplex-1 mutant virus, dlsptk, with reduced neurovirulence, for the effective treatment of malignant human gliomas in cell culture and in nude mouse in vivo models. The range of human nervous system tumors that might be responsive to viral therapy is now expanded. Three medulloblastoma, four malignant or atypical meningioma, and five neurofibrosarcoma cell lines or early-passage tumors were treated with the dlsptk virus in cell culture. A cell death rate of at least 99% was evident in every tumor tested for at least one multiplicity of infection within 14 days after treatment. Control tumor cell cultures remained viable. To test dlsptk therapy in vivo, the authors treated human medulloblastoma subcutaneous xenografts with two doses of dlsptk. Mean growth ratios were significantly inhibited in the treated group when compared to control tumors, and there was a significant number of tumor regressions in the treated animals. Similar results were seen with human malignant meningioma xenografts in a subrenal capsule study. These results encourage the further investigation of viral therapy in the treatment of a broad spectrum of nervous system tumors refractory to conventional treatment methods.
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PMID:Expanded spectrum of viral therapy in the treatment of nervous system tumors. 132 12

A gene transfer model was developed which allows for the identification of transformation pathways in the developing nervous system. Transforming genes were introduced into fetal brain transplants using embryonic CNS as donor tissue and replication-defective retroviral vectors as genetic vehicles. This technique relies on the extraordinary organotypic differentiation capacity of neural grafts and the expression of retrovirally transmitted genes in various cell types of CNS transplants. In contrast to transgenic animals but analogous to sporadic tumor formation, target cells for the retroviral vector develop in an environment of unmodified neural tissue. We have introduced a number of neurotropic oncogenes into fetal brain transplants including genes with an associated tyrosine kinase activity (polyoma medium T, v-src), a novel member of the fibroblast growth factor (fgf) gene family and the SV40 large T antigen. These experiments have demonstrated a significant transformation potential of oncogenes in specific target cells of the brain, provided evidence for a dominant complementary transforming effect of simultaneously expressed ras and myc genes in neural precursor cells and have yielded intriguing model systems for human CNS neoplasms such as the cerebellar medulloblastoma. This review describes the transplantation model, demonstrates several striking phenotypes induced by oncogene expression in neural grafts and elaborates on future prospects of this experimental approach.
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PMID:Retrovirus-mediated oncogene transfer into neural transplants. 134 47

Loss of heterozygosity for sequences located on chromosome 17p in several tumor types is often associated with mutations in the tumor suppressor gene p53. We previously showed consistent deletion of chromosome 17p12-13.1 in medulloblastoma, a common childhood brain tumor. Using denaturing gradient gel electrophoresis and direct sequencing, we have detected p53 mutations in only two of 20 medulloblastoma specimens. Moreover, additional RFLP studies of these 20 specimens showed loss of heterozygosity at a more distal and distinct site, 17p13.3. Deletion of 17p almost invariably signified a negative prognosis. Our results suggest that p53 mutations may contribute to the pathogenesis of medulloblastoma in relatively few cases. The consistent deletion of other discrete loci on 17p suggests that additional or alternative tumor suppressor genes may contribute to the tumor's phenotype.
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PMID:Involvement of multiple chromosome 17p loci in medulloblastoma tumorigenesis. 134 96

Mechanisms of tumor resistance to 4-hydroperoxycyclophosphamide (4-HC) were studied by using a panel of human medulloblastoma cell lines either passaged in the laboratory for resistance to 4-HC or established from tumors showing clinical resistance to cyclophosphamide. Multiple distinct mechanisms of resistance were demonstrated. Daoy (4-HCR), a line that was 6-fold more resistant than Daoy, contained elevated levels of aldehyde dehydrogenase (ALDH). Most of the difference in sensitivity between the Daoy (4-HCR) and Daoy cell lines was abolished when 4-HC was replaced with phenylketocyclophosphamide, a 4-HC analogue that cannot be detoxified by ALDH. Thus, elevated levels of ALDH appear to play a role in the resistance of Daoy (4-HCR). Several of the cell lines [D283 Med (4-HCR), D341 Med (4-HCR), Daoy (4-HCR), D458 Med] contained elevated levels of glutathione (GSH). No changes in glutathione-S-transferase activity or isozyme pattern were observed, but in two of these three lines, the elevation in GSH was accompanied by elevated levels of gamma-glutamyl transpeptidase. To confirm the role of elevated GSH content in 4-HC resistance, the sensitivity of the cell lines to 4-HC was repeated after depletion of GSH by treatment with L-buthionine-S,R-sulfoximine. In medulloblastoma cell lines without other mechanisms of resistance, a linear relationship was seen between GSH content and resistance to 4-HC. Moreover, cells with GSH content greater than 5 nmol/mg protein and no other overriding mechanism of resistance could be sensitized to 4-HC treatment with L-buthionine-S,R-sulfoximine. Finally, D283 Med (4-HCR) cells had mild elevations in both ALDH and GSH content, but were resistant to phenylketocyclophosphamide and were not significantly sensitized by L-buthionine-S,R-sulfoximine. This cell line appears to demonstrate a third mechanism of resistance to 4-HC. These results suggest that 4-HC resistance in medulloblastoma can be multifactorial.
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PMID:Cyclophosphamide resistance in medulloblastoma. 135 17

Significant advances have recently been made in a number of areas concerning central nervous system (CNS) neoplasia. Particularly salient are the following: (1) gene amplification is related to increasing grade of human glioma malignancy and occurs in approximately 40% of the most common and most malignant variety of glioma, glioblastoma multiforme (GBM), (2) by far the most commonly amplified gene in glioblastomas is the epidermal growth factor receptor (EGFR) gene, which is amplified in about one third of GBMs, (3) a small percentage of GBMs amplify N-myc or the novel sequence gli, (4) the EGFR gene is rearranged in at least half of gliomas in which it is amplified, and (5) EGFR gene rearrangement results in external domain deletions that yield truncated EGF receptors. Antibodies specific for the mutant EGF receptor fusion junction have been successfully produced and provide stimulating new potential avenues for tumor imaging and therapy. For pediatric CNS neoplasms, only medulloblastoma has been investigated in adequate numbers; a small percentage exhibit amplification of either the N-myc or c-myc genes.
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PMID:Amplified cellular oncogenes in neoplasms of the human central nervous system. 137 22


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