Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pancreatic insulinomas were intraoperatively revealed in 15 patients. X-ray computed tomography (CAT) revealed the tumor in only 6 (40 %) patients. The mean size of detectable insulinomas was 2.4 cm, that of undetectable ones 1.2 cm. X-ray CAT diagnosis is facilitated in case of a superficial localization of the tumor on the body or tail of the gland .
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PMID:[The role of x-ray computed tomography in the topical diagnosis of insulinomas of the pancreatic gland]. 144 Dec 7

CAT was carried out in 110 patients with gastric carcinoma and its findings compared with the intraoperative findings. CAT involved a polypositional scanning (depending on the tumor site) against the background of oral contrast label of the stomach and intestine. CAT potentialities in the diagnosis of gastric carcinoma, assessment of the tumor size and involvement of the adjacent organs and structures, detection of the metastases were studied. Use of CAT in complex with other methods will help choose the optimal treatment strategy and determine the volume of supposed surgical intervention.
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PMID:[Computed tomography in the diagnosis of stomach cancer and the assessment of its spread]. 144 Dec 6

The effects of combined vitamin C and K3 i.p. injected 3 hours before i.p. administration of single dose of oncovin, to which the ascites liver tumor in mouse (T.L.T.) was completely resistant, were investigated. This pretreatment sensitized the tumor resistant to oncovin, whereas a separate pretreatment with vitamin C or K3 alone was without any effect. This tumor sensitization to the chemotherapy was completely suppressed by catalase pretreatment, thus indicating that hydrogen peroxide generation with subsequent oxidative stress and its consequences may be involved here. Since this sensitization was without any increased general and organ toxicity, its possible introduction into classical protocols of human cancer treatment would be without any supplementary risk.
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PMID:Non-toxic sensitization of cancer chemotherapy by combined vitamin C and K3 pretreatment in a mouse tumor resistant to oncovin. 144 32

Based on the classical observation that catalase activity is reduced in the liver of a tumor bearing host, we studied this phenomenon from the aspect of gene expression. Northern blot analysis on the livers of mice with a rat tumor showed that the catalase gene expression is lowered in a tumor size-dependent fashion. Decreased gene expression was also seen irrespective of tissue or species origin of tumors transplanted. Removal of the implanted tumor resulted in restoration of the reduced gene message to the normal level. The tumor effect on the catalase gene expression was shown to be controlled at the transcriptional level. These results strongly suggest that the reduction of liver catalase activity in the tumor bearer may be due to down regulation of the catalase gene induced in the liver by a certain humoral factor(s) from the transplanted tumor.
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PMID:Depression of catalase gene expression in the liver of tumor bearing nude mice. 147 18

Significant changes have been recorded in the concentration of sulfhydryl groups, histidine, lipoproteins, catalase activity, saponin resistance, and kinetics of chemiluminescent responses of red blood cells in lymphoma patients. Lymphosarcoma is characterized by changes in the structure and function of red blood cells at the early stage of the process, whereas in lymphogranulomatosis changes are observed with the disease progressing, when pronounced signs of tumor intoxication are noted and anemia is present. In lymphosarcoma patients an increase of peripheral blood mononuclears is recorded which expresses the erythroid differentiating antigens with the use of monoclonal antibodies against glycophorin A (ZAE-3) and human erythroblast antigen AG-EB (HAE-9). In lymphogranulomatosis patients it was not detected.
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PMID:[Structure and function of erythrocytes in lymphomas]. 147 24

Activities of superoxide dismutase (SOD) and catalase as well as content of malonyl dialdehyde (MDA) were estimated in the blood of patients with tumor of gastrointestinal tract. In the early stage of development of tumor SOD activity and concentration of MDA in whole blood was decreased while catalase activity was increased significantly. In the cases of metastases spreading and cachexia both SOD and catalase activities were greatly decreased; the content of MDA was increased.
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PMID:[Free radical reactions and cancer]. 149 95

Human tumor cell lines that do not express O6-methylguanine-DNA methyltransferase (MGMT) in detectable quantities (Mer-) are hypersensitive to the effects of O6-guanine-alkylating agents. Because the Mer- phenotype enhances tumor response to such agents, we investigated possible mechanisms involved in regulation of MGMT expression in a panel of Mer+ and Mer- pediatric rhabdomyosarcoma xenograft and cell lines. All Mer- cell and xenograft lines lacked not only MGMT activity but also the protein and mRNA as well, suggesting that its expression is transcriptionally regulated. Transfection of Mer+ and Mer- rhabdomyosarcoma cell lines with MGMT gene promoter-CAT constructs yielded similar levels of CAT expression, indicating that Mer- cells possessed the necessary factors to support transcription. Methylation in the 5'-untranslated region of the MGMT gene was assayed by Southern analysis using methylation-sensitive restriction enzymes. Digestion with HpaII and its methylation-insensitive isoschizomer, MspI, revealed little overall correlation between methylation and MGMT expression. However, methylation in a single SmaI site at position-69 was observed in all MGMT deficient lines but not in any MGMT expressing lines. These results suggest that methylation of specific cytosines in the MGMT promoter may play a role in suppressing its expression, as well as being a potentially useful marker for the Mer- phenotype.
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PMID:Cytosine methylation and suppression of O6-methylguanine-DNA methyltransferase expression in human rhabdomyosarcoma cell lines and xenografts. 150 76

Activating mutations of the Gs alpha subunit have been identified in a subset of somatotroph adenomas. The mutant form of the Gs alpha subunit causes persistent activation of adenylyl cyclase and consequently results in high intracellular levels of cAMP. Because cAMP is known to stimulate the synthesis of the glycoprotein hormone (GPH) alpha-subunit as well as GH, we examined somatotroph tumors with and without Gs alpha mutations for GPH alpha-subunit production. GPH alpha-subunit production was assessed in vivo by measuring serum hormone levels and in vitro by analyzing hormone secretion by cultured pituitary tumor cells. DNA was extracted from the pituitary tumors of 26 acromegalic patients. The Gs alpha gene was amplified by the polymerase chain reaction and screened for mutations at codons 201 and 227 using oligonucleotide specific hybridization. Nine of the 26 tumors (35%) had point mutations at Arg 201. Seven of these tumors contained a CGT to TGT mutation (Arg to Cys) and 2 contained a CGT to CAT mutation (Arg to His). No mutations were detected at codon 227. There were no significant differences in age, sex distribution, tumor size, or serum levels of GH or insulin-like growth factor-1 between the groups of patients with or was Gs alpha mutations. The mean serum level of the free GPH alpha-subunit was 1.9-fold higher in the group with Gs alpha mutations (0.48 +/- 0.37 micrograms/L) than in patients without mutations (0.25 +/- 0.17) (P less than 0.05). In pituitary tumor cell culture, 75% of somatotroph tumors with Gs alpha mutations secreted free GPH alpha-subunit into the media compared with 45% of tumors without Gs alpha mutations. The amount of GPH alpha-subunit secretion was 12-fold greater in the group of tumors containing the Gs alpha mutation (P less than 0.05). Immunocytochemical detection of the free GPH alpha-subunit was similar in the two groups of patients with 75% positive for the GPH alpha-subunit in tumors with Gs alpha mutations and 67% positive in tumors without mutations (P = 0.69). We conclude that GPH alpha-subunit production occurs in somatotroph tumors with and without Gs alpha mutations. The increased levels of GPH alpha-subunit secretion in vivo and in vitro suggest that the Gs alpha mutation may increase the amount of preexisting GPH alpha-subunit biosynthesis in the tumors, perhaps via activation of the cAMP pathway.
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PMID:Glycoprotein hormone alpha-subunit production in somatotroph adenomas with and without Gs alpha mutations. 151 86

Clinical and experimental observations suggest that tumor-induced endothelial cell injury may be one of several initial events in the establishment of tumor metastases. To test this hypothesis, the authors have analyzed the interaction of malignant melanoma (ST-ML-12) multicenter tumor spheroids with endothelial cell monolayers in a three-dimensional coculture system. After 1.5 hours of interaction, the authors observed a toxic effect on endothelial cells in the perispheroid region. The latter was demonstrated by testing membrane integrity with the fluorescent probes acridine orange/ethidium bromide and resulted in sensitivity to shear stress of the damaged cells. The endothelium then underwent a regenerative cycle to replace the denuded halo. Addition of the oxygen radical-scavenging enzyme superoxide dismutase to the culture medium prevented this endothelial cell damage in a dose-dependent manner for up to 12 hours. By contrast, catalase, deferoxamine mesylate, allopurinol, and the proteinase inhibitors soybean trypsin inhibitor and aprotinin were not protective under the same conditions. The endothelial damage was dependent on the attachment of the spheroids. Medium conditioned by ST-ML-12-spheroids proved to be ineffective. A similar, but less prominent, deleterious effect was seen when human peritoneal mesothelial cells were used in place of the human umbilical vein endothelial cells. Spheroids of the uroepithelial cell line HU-609 were used as control. No toxicity was observed in these cocultures. Melanin biosynthesis is associated with the production of oxygen-derived free radicals. The results suggest a possible implication of these free radicals in metastasis formation of malignant melanoma.
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PMID:Interaction of human malignant melanoma (ST-ML-12) tumor spheroids with endothelial cell monolayers. Damage to endothelium by oxygen-derived free radicals. 151 67

Increases in acyl coenzyme A (CoA) oxidase activity due to peroxisome proliferation are postulated to cause oxidative stress via elevated production of H2O2, leading to DNA damage. These changes are suspected to be responsible for tumor formation caused by non-genotoxic carcinogens which do not bind to DNA but cause proliferation of peroxisomes. However, the activity of the peroxisomal enzyme acyl CoA oxidase assayed in vitro in the presence of excess fatty acyl CoA substrate may not reflect rates of H2O2 generation in intact liver where fatty acid supply is carefully controlled in part by delivery of substrate. The purpose of this work was to determine if rates of hepatic H2O2 generation were altered in perfused liver and in vivo following induction of H2O2-generating acyl CoA oxidase activity. Injection of the potent peroxisome proliferating agent perfluorooctanoate into rats 5 days prior to sacrifice caused an expected 4-fold increase of H2O2-generating acyl CoA oxidase activity measured in hepatic homogenates. In contrast, rates of H2O2 generation in perfused liver measured spectrophotometrically (660-640 nm) through a lobe of the liver were not altered by perfluorooctanoate treatment (7.3 +/- 1.5 vs. 7.8 +/- 0.5 mumol/g/h in livers from untreated control rats). Similar treatment with perfluorooctanoate also increased in vitro acyl CoA oxidase activity 9-fold in livers from deermice; however, rates of elimination of methanol, a selective substrate for catalase in rodents whose oxidation is limited by the supply of H2O2, were not altered significantly in vivo (control, 110 +/- 11 mumol/g/h vs. perfluorooctanoate, 112 +/- 32 mumol/g/h). Taken together, these data demonstrate that elevation of H2O2 formation by acyl CoA oxidase activity measured in vitro is not necessarily associated with increases in rates of H2O2 generation in intact perfused liver or in vivo, most likely due to rate-limitation in intact cells by fatty acid supply. These data do not support the hypothesis that the induction of peroxisomes leads to excessive H2O2 production and oxidative stress. It follows that alternative hypotheses to explain carcinogenesis caused by peroxisome-proliferating agents need to be considered.
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PMID:Induction of peroxisomes by treatment with perfluorooctanoate does not increase rates of H2O2 production in intact liver. 153 82


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