Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Embryonal rhabdomyosarcomas from the nasopharynx of two children were examined by histochemical methods commonly applied to muscle biopsies. These stains included nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), PAS, PAS-diastase, myophosphorylase, calcium-mediated adenosine triphosphatase (ATPase) preincubated at high and low pH, and oil red O. Myofibrils were easily identified with ATPase and blood vessel walls were also stained. NADH-TR clearly showed longitudinal and cross-striations that were not seen with H&E or PTAH stains. The modified Gomori trichrome stain additionally contributed to the recognition of myofibrils. Some techniques of muscle histochemistry applied to fresh frozen sections of tumor tissue may provide evidence of muscular differentiation in otherwise poorly differentiated sarcomas for a more accurate diagnosis of rhabdomyosarcoma.
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PMID:Diagnostic value of histochemistry in embryonal rhabdomyosarcoma. 9 52

Methylglyoxal treatment of tumour cells in vitro primarily depresses protein synthesis, in contrast to trans-4-hydroxypent-2-enal (HPE) which preferentially inhibits DNA synthesis. Methylglyoxal and hpe are potent carcinostatic agents in vitro but relatively ineffective in vivo. Both aldehydes have a short half-life in vivo which may explain their poor carcinostatic properties when administered other than peritumorally. Several possibilities of increasing the effective half-life were investigated including (i) multiple intraperitoneal injections, (ii) concomitant administration of an inhibitor of glyoxalase I, (iii) administration of aldehyde-cysteine adducts, and (iv continuous intravenous infusion. Methylglyoxal (36 mg/kg i.p., twice daily) was slightly less effective in inhibiting the growth of the solid form of Ehrlich carcinoma than a dose of 72 mg/kg (inj. 1); 36 mg/kg (inj. 2) 46.2% compared to 51%. The aldehyde was more effective aginst the ascitic form of the tumour, with 99.76% inhibition of growth after giving 72 mg/kg twice daily for five days followed by 36 mg/kg for five days. The glyoxalase I inhibitor S-(p-bromobenzyl)-glutathione didnot significantly enhance the activity of methylglyoxal against the solid form of the tumour. Nicotinamide (1% w/v in the drink) was similarily inactive. Methylglyoxal in combination with nicotinamide was significantly more effect (P less than 0.05) than methylglyoxal alone (36 mg/kg, twice daily) in inhibiting the growth of the ascitic tumour. Methylglyoxal-N-acetyl-L-cysteine was four times less toxic than methylglyoxalalone but was marginally less effective against the ascitic form of the tumour. Doses of these adducts equivalent to 144 mg/kg per day of methylglyoxal were more effective P less than 0.05) than the optimal regime of methylglyoxal in inhibiting the solid tumour (67.5% inhibition compared to 51%). Treatment of mice bearing the ascitic form of Sarcoma 180 with five daily doses (i.p.) of an HPE-cysteine adduct equivalent to a dose of HPE alone of 32-256 mg/kg per day significantly increased survival time by comparison with controls. The adduct was 2-3 times more effective, dose-for-dose, than HPE alone in inhibiting tumour growth. Purified buffered methylglyoxal has an LD50 on continuous infusion into the right lateral tail vein in mice of more than 3.0 mg/g per day (seven days at 2.8 ml/day). Local oedema followed by tail necrosis occurs at doses in excess of 0.25-0.5 mg/g per day in mice bearing the solid forms of the syngeneic tumours: squamous carcinoma D; lymphosarcoma 1 (WH/Ht mice); and spontaneous mammary D5056 (CBA/CA mice). A maximum tumour volume growth delay of 3.4 days at Day 17 (P less than 0.001) after transplantation was observed after infusion of 0.5 mg/g per day methylglyoxal on Days 11-17 in the CBA/CA D40 syngeneic mammary tumour. Tumour regrowth after termination of therapy eliminated the significant difference between control and methylglyoxal-treated tumours by Day 27. Methylglyoxal infusion (0...
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PMID:Carcinostatic activity of methylglyoxal and related substances in tumour-bearing mice. 15 13

The initial metabolic products of cyclophosphamide (4-hydroxy-cyclophosphamide and aldophosphamide) were prepared biologically in unpurified form. Their toxicity to tumor cells were tested by bioassay techniques and in cell culture, and the deactivation abilities of various tissue-soluble fractions were quantitated. Liver and kidney cytosol effectively deactivated the primary metabolites, whereas cytosols from gastrointestinal tract mucosa, Walker ascites tumor, and spleen were less efficient. When [14C]cyclophosphamide was activated and incubated with liver cytosol, 34% of all radioactivity was identified as carboxyphosphamide, by mass spectrometry of the methyl ester. Measurement of alcohol dehydrogenase (EC 1.1.1.1) and aldehyde dehydrogenase (EC 1.2.1.3) activities by reduced nicotinamide adenine dinucleotide production revealed a qualitative correspondence between aldehyde dehydrogenase activity and deactivation ability. Unpurified aldophosphamide and the analogs prepared from 6-methyl- and 5,5-dimethylcyclophosphamides were substrates for nicotinamide adenine dinucleotide-requiring enzymes, whereas incubation of 4-hydroxy-4-methylcyclophosphamide in an unfractionated incubation mixture with liver soluble enzymes did not cause reduced nicotinamide adenine dinucleotide production.
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PMID:The enzymatic basis of the selective action of cyclophosphamide. 17 33

Pyruvate dehydrogenase was partially purified from Ehrlich ascites tumor cell mitochondria and its kinetic properties were determined. The apparent KM values for pyruvate, nicotinamide adenine dinucleotide, and coenzyme A (CoA) were 46 muM, 110 muM, and 36 muM, respectively. Reduced nicotinamide adenine dinucleotide and acetyl-CoA inhibited enzyme activity competitively to nicotinamide adenine dinucleotide (Ki = 22 muM) and CoA (Ki = 58 muM), respectively. Copurified alpha-ketoglutarate dehydrogenase displayed apparent KM values for alpha-ketoglutarate, nicotinamide adenine dinucleotide, and CoA of 1.25 mM, 67 muM, and 50 muM, respectively. Pyruvate dehydrogenase, but not alpha-ketoglutarate dehydrogenase, was inactivated specifically by adenosine triphosphate with concomitant phosphorylation, and it was reactivated at 10 mM Mg2+ by a protein fraction separated from the complex during purification. The rate of inactivation was decreased by pyruvate or pyrophosphate. The existence of active and inactive forms of pyruvate dehydrogenase in Ehrlich ascites tumor cells was demonstrated. Active form and total activity were determined to be 74.0 +/- 1.5 and 93.6 +/- 4.9 munits/g packed cells (mean +/- S.E., n = 25), respectively.
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PMID:Kinetic and regulatory properties of pyruvate dehydrogenase from Ehrlich ascites tumor cells. 17 13

Hypoglycemic rats bearing insulin-secreting islet-cell adenomas produced by the combined action of streptozotocin and nicotinamide were treated with streptozotocin. Antitumor response was demonstrated by elevation of blood glucose, reduction in plasma and tumor IRI, and histopathologic changes in the beta-cell neoplasm. The rodent tumor model may serve as a predictive system for selection and investigation of mechanisms of action of future antitumor agents to be used in the treatment of malignant insulinoma in man.
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PMID:Streptozotocin treatment of streptozotocin-induced islet cell adenomas in rats. 17 70

The activity of the malate-aspartate shuttle for the reoxidation of cytoplasmic reduced nicotinamide adenine dinucleotide (NADH) by mitochondria was assessed in six lines of rodent ascites tumor cells (two strains of Ehrlich ascites carcinoma, Krebs II carcinoma, Novikoff hepatoma, AS-30D hepatoma, and L1210 mouse leukemia). All the tumor cells examined showed mitochondrial reoxidation of cytoplasmic NADH, as evidenced by the accumulation of pyruvate when the cells were incubated aerobically with L-lactate. Reoxidation of cytoplasmic NADH thus generated was completely inhibited by the transaminase inhibitor aminooxyacetate. The involvement of the respiratory chain in the reoxidation of cytoplasmic NADH was demonstrated by the action of cyanide, rotenone, and antimycin A, which strongly inhibited the formation of pyruvate from added L-lactate. Compounds that inhibit the carrier-mediated entry of malate into mitochondria, such as butylmalonate, benzenetricarboxylate, and iodobenzylmalonate, also inhibited the accumulation of pyruvate from added L-lactate by the tumor cells. The maximal rate of the malate-aspartate shuttle was established by addtion of arsenite to inhibit the mitochondrial oxidation of the pyruvate formed from added lactate. The capacity of the various tumor lines for the reoxidation of cytoplasmic NADH via the malate-aspartate shuttle approaches 20% of the total respiratory rate of the cells and thus appears to be sufficient to account for the mitochondrial reoxidation of that fraction of glycolytic NADH not reoxidized by pyruvate and lactate dehydrognenase in the cytoplasm.
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PMID:Occurrence of the malate-aspartate shuttle in various tumor types. 17 6

Islet beta cell adenomata were induced in rats by combined treatment with nicotinamide and streptozotocin. Three weeks after treatment marked alterations in glucose tolerance were noted in animals which later exhibited large beta cell tumors. Eight months after treatment, the rats known to have beta cell tumors on the basis of marked hypoglycemia and later confirmed by autopsy showed variable response to a glucose load. Some tumor-bearing rats showed fast response to glucose load, their blood sugar levels were elevated moderately and returned to normal or below normal levels rapidly; these animals are described as having "fast-acting tumors". Rats with "slow-acting tumors" responded sluggishly to a glucose load; their blood glucose pattern was similar to that of subdiabetic animals. Animals with beta cell tumors exhibited elevated serum insulin levels 30 min after glucose administration. Insulin biosynthesis by beta cell adenomata was demonstrated by in vitro incorporation of [14C]leucine into proinsulin and insulin. In the small number of tumor samples studied, a stimulatory effect of glucose on insulin biosynthesis was observed.
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PMID:Studies on rats with islet beta cell tumors induced by nicotinamide and streptozotocin. 18 May 43

The bioreductive alkylating agent, 2,3-bis(chloromethyl)-1,4-napthoquinone (CMNQ), has been shown to inhibit the growth of Sarcoma 180 ascites cells in vivo. Evidence for the reductive activation of this agent via the mitochondrial respiratory chain was provided by CMNQ-induced oxidation of reduced nicotinamide adenine dinucleotide; the interaction was shown to be on the substrate side of the site of rotenone inhibition. Consistent with the concept that reduction of CMNQ to a hydroquinone results in the generation of an alkylating species (i.e., a quinone methide) was the finding that radioactivity from [14C]CMNQ present in Sarcoma 180 ascites cells was associated with DNA, RNA, and protein for a period of up to 72 hr after exposure to tumor-bearing animals to this agent. Inhibition of the incorporation of [3H]thymidine, [3H]uridine, and [14C]leucine into DNA, RNA, and protein, respectively, of Sarcoma 180 ascites cells was produced by this agent, with DNA biosynthesis being the most susceptible. The inhibitory effect of CMNQ on the formation of DNA was, at least in part, the result of a prevention of the conversion of thymidine to its nucleotide forms. This action was due to (a) a drug-induced decrease in intracellular levels of adenosine 5'-triphosphate, presumably resulting from uncoupling of oxidative phosphorylation by CMNQ; and (b) a partial loss of thymidine kinase activity in Sarcoma 180 cells, which did not appear to be due to direct inhibition of the enzyme by the drug. Although the primary event produced by CMNQ at the mitochondrial level appeared to be release of respiratory control, other effects of mitochondrial metabolism occurred. These included inhibition of reduced nicotinamide adenine dinucleotide and succinoxidase activities, as previously demonstrated, and mitochondrial swelling, which suggested interaction of CMNQ with the inner mitochondrial membrane. These findings indicate a variety of biochemical lesions are associated with the antineoplastic activity of CMNQ and demonstrate a relationship between the effects of this drug on mitochondrial respiratory control and DNA biosynthesis.
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PMID:Mode of action of the bioreductive alkylating agent, 2,3-bis(chloromethyl)-1,4-naphthoquinone. 18 23

Poly(ADP-ribose) polymerase with a high specific activity was obtained from Ehrlich ascites tumor cells by extraction of nuclei with 175 mM potassium phosphate, followed by chromatography on DNA-agarose. Electrophoretic analysis indicated that the preparation contained two proteins, one of which was shown to catalyze the synthesis of poly(ADP-ribose). As expected from results obtained by other workers, the synthesis was inhibited by nicotinamide and thymidine, and stimulated by DNA. Addition of histones gave inhibition of the synthesis, unless DNA was present in the reaction mixture.
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PMID:Purification of poly(ADP-ribose) polymerase from Ehrlich ascites tumor cells by chromatography on DNA-agarose. 18 48

Measurements of respiration, CO2 and lactate production, and changes in the levels of various key metabolites of the glycolytic sequence and tricarboxylic acid cycle were made on five lines of rodent ascites tumor cells (two strains of Ehrlich ascites tumor cells, Krebs II carcinoma, AS-30D carcinoma, and L1210 cells) incubated aerobically in the presence of uniformly labeled D-[14C]glucose. From these data, as well as earlier evidence demonstrating that the reduced nicotinamide adenine dinucleotide (NADH) shuttle in these cells requires a transaminase step and is thus identified as the malate-aspartate shuttle (W.V.V. Greenhouse and A.L. Lehninger, Cancer Res., 36: 1392-1396, 1976), metabolic flux diagrams were constructed for the five cell lines. These diagrams show the relative rates of glycolysis, the tricarboxylic acid cycle, electron transport, and the malate-aspartate shuttle in these tumors. Large amounts of cytosolic NADH were oxidized by the mitochondrial respiratory chain via the NADH shuttle, comprising anywhere from about 20 to 80% of the total flow of reducing equivalents to oxygen in these tumors. Calculations of the sources of energy for adenosine triphosphate synthesis indicated that on the average about one-third of the respiratory adenosine triphosphate is generated by electron flow originating from cytosolic NADH via the malate-aspartate shuttle.
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PMID:Magnitude of malate-aspartate reduced nicotinamide adenine dinucleotide shuttle activity in intact respiring tumor cells. 19 30


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