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

Oxidative modification of genetic material has been implicated as a factor in carcinogenesis, particularly during promotion and progression, and therefore there is a need for sensitive detection of oxidized DNA bases. We developed a method that can be applied to DNA isolated from any source and used to simultaneously quantify oxidized nucleosides without a need to prelabel the DNA or use destructive hydrolytic procedures. This method is based on: (a) enzymatic DNA digestion; (b) HPLC separation of the resultant nucleosides; (c) acetylation of the oxidized nucleosides with [3H]Ac2O (acetic anhydride); (d) removal of the radioactive debris; and (e) quantitative analysis of tritiated nucleoside acetates by HPLC. Enzymatic DNA digestion was optimized using DNase I in the presence of Mg2+ (pH 7), followed by nuclease P1 in the presence of Zn2+ (pH 5.1) and alkaline phosphatase (pH 7.5). Analysis of DNA oxidized with H2O2 in the presence of Fe2+/EDTA for 30 min showed that the levels of 8-OHdG (8-hydroxy-2'-deoxyguanosine) were increased 2.7-fold, HMdU (5-hydroxymethyl-2'-deoxyuridine) 3.15-fold, and FdU (5-formyl-2'-deoxyuridine) 2.5-fold. Although the (-)-isomer of cis-dTG (cis-thymidine glycol) was enhanced 2.3 times, the (+)-isomer remained virtually unchanged. Analysis of DNA isolated from epidermal cells of mice treated in vivo with the tumor promoter TPA (12-O-tetradecanoylphorbol 13-acetate) showed 4.8-, 2.7-, and 8.7-fold increases in the levels of total cis-dTG, 8-OHdG, and HMdU, respectively, and of some unknown DNA oxidation products. These results prove applicability of the 3H-postlabeling method to the analysis of DNA (and potentially RNA) isolated from many sources, including animals and humans.
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PMID:Quantitative high-performance liquid chromatography analysis of DNA oxidized in vitro and in vivo. 188 26

The existence of a single or of multiple populations of glibenclamide binding sites is a subject of controversy. In the present study, radioligand binding techniques were employed to determine whether multiple populations of [3H]glibenclamide binding sites exist in pancreatic tumor (insulinoma) cells. Additional studies were performed to further characterize the binding of [3H]glibenclamide to insulinoma and cardiac membranes. [3H]Glibenclamide bound to high (0.1 nM) and low (240 nM) affinity binding sites in insulinoma membranes. The physiological relevance of multiple populations of sites is unknown. The binding of glibenclamide to insulinoma and cardiac membranes was altered by guanine nucleotides and not adenine nucleotides. This suggests glibenclamide binding can be modulated by G-proteins. Glibenclamide binding was also modulated by divalent cations. The divalent cations, Ca2+ and Zn2+, stimulated specific glibenclamide binding to cardiac and insulinoma membranes, while Mg2+ and Mn2+ enhanced cardiac binding only. Moreover, the lowering of pH from 7.4 to 6.5 was found to enhance specific glibenclamide binding. Interestingly, the magnitude of this effect was much larger in cardiac membranes. The specific nature of the regulation of glibenclamide binding by guanine nucleotides, divalent cations and pH remains to be explored.
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PMID:Modulation of [3H]glibenclamide binding to cardiac and insulinoma membranes. 191 93

Zinc speeds up a lot of metabolic processes because it is essential for a lot of enzymatic reactions. A modification of the zinc pool may influence the tumor growth. We used an animal model where we applied the Yoshida sarkoma intraperitoneally in its ascites form to parenterally fed Sprague-Dawley rats. Four groups with ten tumor bearing (TBR) and ten non-tumor-bearing rats (NTBR) each received different parenteral nutrition. The normocaloric Group 1 and the hypocaloric (reduced to 1/3 energy) Group 2 were fed without zinc. In Groups 3 (normocaloric) and (hypocaloric) high doses of zinc (0.519 mg/500 g Kg/d) were substituted. In Group 3 we found the quantitatively and qualitatively highest proof of tumor mass. The nitrogen content of the ascites wasn't significantly changed within the groups. We found a weight loss of the NTBR with zinc substitution. Zinc improves the synthesis of the tumor and leads to a weight loss of the host in our animal model.
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PMID:[Does varied parenteral zinc administration modify interaction between tumor and host? Studies based on an animal model]. 191 53

The aim of the experiment was to study the effect of three specialized food rations on activity of superoxide dismutase (SOD) in tissues of rats with transplanted Walker's carcinosarcoma 256 exposed to carminomycin. It was shown that the three specialized rations were able to significantly modify the SOD activity in the tissues of the rats with Walker's carcinosarcoma 256 at the background of treatment with carminomycin. Thus, the ration enriched with copper and zinc salts and folic acid activated SOD in the animals of all the groups. Still, the effect was higher in the tumor-bearing animals and the rats treated with carminomycin i.e. under conditions of oxidative stress. The use of the ration enriched with sulfur-containing amino acids, sodium selenide and vitamin E led to decreasing of the efficiency of the fermentative dismutation of O2 in the healthy rats and marked activating of SOD in the tumor-bearing animals. The ration containing lyophilized vegetables and vitamin E provided a significant increase in the SOD activity in the healthy rats. However, its potential was not sufficient for overcoming the SOD inhibiting effect of the tumor growth.
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PMID:[Alimentary methods of maintaining the superoxide dismutase activity in the tissues of rats during growth of a transplanted tumor and administration of carminomycin]. 195 87

Extracellular ATP is shown here to induce programmed cell death (or apoptosis) in thymocytes and certain tumor cell lines. EM studies indicate that the ATP-induced death of thymocytes and susceptible tumor cells follows morphological changes usually associated with glucocorticoid-induced apoptosis of thymocytes. These changes include condensation of chromatin, blebbing of the cell surface, and breakdown of the nucleus. Cytotoxicity assays using double-labeled cells show that ATP-mediated cell lysis is accompanied by fragmentation of the target cell DNA. DNA fragmentation can be set off by ATP but not the nonhydrolysable analogue ATP gamma S nor other nucleoside-5'-triphosphates. ATP-induced DNA fragmentation but not ATP-induced 51Cr release can be blocked in cells pretreated with inhibitors of protein or RNA synthesis or the endonuclease inhibitor, zinc; whereas pretreatment with calmidazolium, a potent calmodulin antagonist, blocks both DNA fragmentation and 51Cr release. The biochemical and morphological changes caused by ATP are preceded by a rapid increase in the cytoplasmic calcium of the susceptible cell. Calcium fluxes by themselves, however, are not sufficient to cause apoptosis, as the pore-forming protein, perforin, causes cell lysis without DNA fragmentation or the morphological changes associated with apoptosis. Taken together, these results indicate that ATP can cause cell death through two independent mechanisms, one of which, requiring an active participation on the part of the cell, takes place through apoptosis.
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PMID:Extracellular ATP as a trigger for apoptosis or programmed cell death. 198 62

Pretreatment or "priming" with vincristine (VcR) has been documented to radioprotect animals from whole body irradiation by accelerating recovery of hematopoietic marrow. The mechanisms underlying this phenomenon are unclear, but the marked similarities between priming with VcR and with immune stimulants such as endotoxin and glucan have led to speculation that VcR may be inducing such radioprotective immunoregulators as interleukin 1 (IL-1) and tumor necrosis factor (TNF). The radioprotective ability of these cytokines, in turn, has been linked to an induction of the antioxidant enzyme manganese superoxide dismutase (Mn SOD). To establish whether priming with VcR is associated with induction of antioxidant enzymes, the activities of Mn SOD, copper-zinc (Cu-Zn) SOD, catalase (CAT), and glutathione peroxidase (GPX) were measured in the marrow of both LLca tumor-bearing and non-tumor-bearing mice given a priming dose of VcR. Results in non-tumor-bearing mice indicate that, similar to IL-1 and TNF administration, VcR treatment increases Mn-SOD activity, but not Cu-Zn SOD, CAT, or GPX activity. Furthermore, this increase occurs at the time VcR priming has been demonstrated previously to exhibit maximal radioprotection, suggesting that it may be contributing factor. However, VcR priming has been demonstrated to radioprotect both tumor-bearing and non-tumor-bearing animals, and no increase in Mn SOD activity (or the other enzymes monitored) was found in the tumor-bearing group. Rather, the presence of tumor significantly suppressed antioxidant enzyme activity. Collectively, the present data suggest that it is unlikely that increased antioxidant enzyme activity is directly involved in the VcR priming response.
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PMID:Marrow antioxidant enzyme activity in tumor-bearing and non-tumor-bearing mice following vincristine treatment. 199 2

Antibody-associated paraneoplastic cerebellar degeneration (the Yo syndrome) is an uncommon disorder in which an immune response is specifically directed against tumor tissue and the cerebellum. Screening of a lambda expression library has resulted in the isolation of cDNA clones that encode the major antigen recognized by serum from these patients. The fusion protein produced by the cDNA clones provides the basis of a simple diagnostic assay for this neurological syndrome. The occurrence of leucine-zipper and zinc-finger motifs in the predicted open reading frame suggests that this protein plays a role in the regulation of gene expression.
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PMID:Cloning of a leucine-zipper protein recognized by the sera of patients with antibody-associated paraneoplastic cerebellar degeneration. 201 64

Though it is known that excess zinc will prevent cadmium carcinogenesis, the impact of zinc deficiency on cadmium carcinogenesis has not been defined. This study assessed the effect of dietary zinc deficiency on the carcinogenic potential of cadmium in rats. Groups (n = 28 each) of male Wistar [Hsd: (WI)BR] rats were fed diets adequate (60 ppm) or deficient (7 ppm) in zinc and received a single sc dose of cadmium (5, 10, or 30 mumol Cd/kg). Lesions were assessed over the next 92 weeks. All cadmium doses increased the incidence of testicular interstitial cell tumors. The incidence of cadmium-induced testicular tumors was unaffected by dietary zinc status. However, when multiplicity of testicular lesions was considered, zinc-deficient diets markedly increased the number of testicular interstitial cell adenomas generated by cadmium exposure while significantly reducing the number of preneoplastic lesions (interstitial cell hyperplasias). The combined total number of neoplastic and preneoplastic lesions of the testes was independent of zinc status clearly indicating a shift from hyperplasia to neoplasia within the testes of zinc-deficient rats. The highest cadmium dose (30 mumol/kg) increased injection site sarcomas in zinc-deficient rats (7 tumors/27 rats at risk) but not zinc-adequate rats (3/26) when compared to control (0/49). Chronic progressive renal nephropathy was accelerated by cadmium in zinc-deficient rats. Results indicate that dietary zinc deficiency enhances carcinogenic response at the injection site of cadmium, promotes the neoplastic progression of cadmium-induced testicular lesions, and enhances chronic progressive nephropathy. Thus, dietary zinc deficiency appears to cause a generalized increase in the chronic toxic effects of cadmium.
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PMID:Effect of chronic dietary zinc deficiency on cadmium toxicity and carcinogenesis in the male Wistar [Hsd: (WI)BR] rat. 202 Sep 69

In order to make electrolytic tumor destruction more effective new electrode materials were tested (Part I) as well as a combination of electrolysis and megavolt therapy (Part II). All tests were performed in experimental tumors implanted subcutaneously in rats. Altogether in 41 rats in 5 series (Part I) electrodes made of rhodium (Rh), copper (Cu), or brass (Zn-Cu alloy) were investigated but the effect was not found to be better than that of the previously tested platinum (Pt). Oxidation and corrosion made Rh and Cu electrodes less suitable for electrolysis compared to Pt, while brass electrodes became isolated through zinc-salt-formation and performed unsatisfactorily. The radiosensitizing properties of electrolysis were tested in 55 rats with experimental tumors (Part II). One control group had only Co-irradiation, while in 2 other groups Cu- or Pt-electrolysis of the tumors was carried out before irradiation. The combined treatment resulted in a significantly better effect on the tumors, registered as inhibition of tumor growth or disappearance of tumor. As the electrolyzed, necrotic tissue remained in the tumor the effect might not be mediated through diminished target volume. An inflammatory reaction around the electrolytic lesion with increased blood flow and higher oxygenation of the tumor could cause a more positive response to megavolt treatment.
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PMID:Electrolysis with different electrode materials and combined with irradiation for treatment of experimental rat tumors. 203 6

Carcinogenic metal levels in serum and tissue samples were measured in patients with bronchopulmonary or colorectal cancer. The cadmium and nickel tissue levels in the patients with lung cancer were significantly higher than in the controls. A statistical correlation was found between chromium and cadmium, as well as between cadmium and nickel in patients with colorectal cancer. In addition, prior to the operation, the tumor markers alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (Ca 19-9), polypeptide histidio antigen (TPA) and ferritin were analyzed. Their average concentrations were correlated with the existing concentrations of the metals. This was done for both types of cancer. Tumor marker detection showed an increase of CEA and TPA in patients with colorectal cancer. A statistical correlation was observed between AFP and zinc tumor tissue.
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PMID:Comparative analysis of certain metals and tumor markers in bronchopulmonary cancer and colorectal cancers. Metals and tumor markers in the neoplastic process. 210


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