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

This time trend of hemodynamics and mitochondrial functions were studied to determine whether the ligation of the hepatic artery would result in an antitumor effect on 3'-methyl-4-dimethylaminoazobenzene-induced hepatic carcinoma in rats. The studies revealed that the hepatic tumors were nourished predominantly by the artery and less by the portal vein; the size of the vascular beds in the hepatic tumors decreased as compared with those in the non-tumor area; and as the tumors grew larger, the artery became less predominant and the size of vascular beds decreased further. The mitochondria in the tumor were characterized by impaired growth, impaired oxidative phosphorylation, and by the low activity and nucleotide specificity of membrane bound ATPase. Hepatic dearterialization enhanced ischemia in the tumors and was accompanied by intensified impairment of the aerobic energy production, resulting in necrosis of the tumor. The effects of the dearterialization tended to decrease after the 5th day following the operation. In view of the gross findings upon relaparotomy and the recovery of hemodynamics and mitochondrial functions, this tendency appeared to be chiefly attributed to the increasing collateral circulation.
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PMID:Hepatic dearterialization in 3'-methyl-4-dimethylaminoazo-benzene-induced hepatocellular carcinoma with special reference to circulatory dynamics and mitochondrial functions. 16 34

Mitochondria from a rat mammary tumor (R3230AC) have been compared with mitochondria from pregnant and lactating rat mammary glands, with particular attention paid to inner membrane enzymes and Transport proteins. In the tumor the mitochondrial adenosine triphosphatase was not activated by 2,4-dinitrophenol, in contrast to the mammary mitochondria from lactating or pregnant rats. Translocation of adenosine diphosphate across the inner membrane was found to be more rapid in the tumor by virtue of lovered Km adenosine diphosphate and raised Vmax. Transport of phosphate and dicarboxylic acids occurred at similar rates in all three types of mitochondria. The inner membrane proteins were also examined directly by sodium dodecyl sulfate/polyacrylamide gel electrophoresis and some differences are noted. These results, although they indicate subtle differences between the inner mitochondrial membranes of tumor as compared with those of pregnant or lactating rat mammary glands, cannot form the basis of an explanation for enhanced glucose utilization and aerobic lactic acid production in this tumor.
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PMID:A comparative study of inner membrane enzymes and transport systems in mitochondria from R3230AC mammary tumor and normal rat mammary gland. 16 45

The induction of concomitant immunity was studied in Donryu strain rats with Yoshida ascites sarcoma cells. The changes of enzyme activity in spleen lymphocytes were also examined in normal and tumor-bearing rats. The concomitant immunity was detected 1 week after transplantation of tumor cells. Extended metastases were found 2 weeks after transplantation. The enzyme activities of ATPase and acid phosphatase were definitely higher than that of normal rat 1 week after the transplantation but decreased to lower level than normal 2 weeks later. On the other hand, alkaline phosphatase activity increased 3 times at 1 week after the transplantation and remained at the same level even at 2 weeks later.
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PMID:Changes of enzyme activities in spleen lymphocytes from tumor-bearing rats. 17 Nov 91

Mitochondria were isolated from Morris hepatomas with rapid (types 3683, 7777, and 3924A) and intermediate (types 5123D and 7800) growth rates, using proteolytic digestion of minced tumor tissue to release the particles. Mitochondria isolated by the same procedure from rat liver were employed as controls. All the hepatoma mitochondria were capable of coupled respiration with normal phosphorylation yields (ADP/O) and respiratory control ratios ranging from 2 to considerably more than 10. Particles from hepatomas 7777 and 7800 exhibited properties closest to liver mitochondria, while those from hepatomas 3683 and 3924A showed the greatest difference. All the hepatoma mitochondria were capable of oxidizing succinate, 3-hydroxybutyrate and monoamines. However, the oxidation rates of the latter two substrates by mitochondria from hepatomas 3683 and 3924A were only a fraction of the control rates. These differences appeared to be due, at least in part, to the structural instability of the isolated hepatoma mitochondria. In contrast to the reports of others, all hepatoma mitochondria exhibited considerable stimulation of ATPase activity by uncouplers. Maximal stimulation of ATPase activity by representatives of three classes of uncouplers was in all instances comparable to the values obtained for rat liver mitochondria.
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PMID:Oxidative phosphorylation properties of mitochondria isolated from transplanted hepatoma. 18 16

Six young adult male rhesus monkeys were given diethylnitrosamine ip for 3-5 years. Liver biospies were done monthly. After 6 months, biopsy specimens showed individual hepatocytes and small foci of hepatocytes that were intensely positive for glycogen. During the second and later years, larger foci of such cells developed. In sections stained with hematoxylin and eosin, the glycogen-containing hepatocytes generally appeared unusually clear. Some hepatocytes, however, had eosinophilic or basophilic cytoplasm. Nuclear enlargement and atypic developed, particularly outside the foci. The hepatocytes within most foci were uniform in their histochemical features: glycogen was elevated, glucose-6-phosphatase was decreased, and ATPase activity was present not only along the bile canalicular surface but also along the enire cell membrane. After 3-5 years, neoplastic nodules and hepatocarcinomas developed in 5 of 6 animals. Two nodules and particularly the heptocarcinomas differed from the foci in one of more histochemical parameters. The findings suggested that the glycogen-containing, histochemically altered cells of the foci in one or more histochemical parameters. The findings suggested that the glycogen-containing, histochemically altered cells of the foci may be the first step in the development of neoplasia; further steps toward malignancy appeared to be frequently associated with additional alterations, such as loss of sinusoidal ATPase and re-formation of glucose-6-phosphatase.
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PMID:Sequential hepatic histologic and histochemical changes produced by diethylnitrosamine in the rhesus monkey. 18 98

Ectodermal cells of the two- and three-germ layer-thick mouse egg-cylinders are considered to be the progenitors of embryonal carcinoma cells in embryo-derived teratocarcinomas. In an attempt to find differences between the tumor cells and equivalent embryonic cells, we have studied the electron microscopic cytochemical localization of alkaline phosphatase, 5'-nucleotidase, and Mg2+-activated adenosine triphosphatase (ATPase) in embryo-derived teratocarcinomas and mouse egg-cylinders. Alkaline phosphatase was detected in both embryonic and tumor cells, but its activity appeared much more intense in the tumor cells. No ATPase was demonstrated in embryonic ectodermal cells of 6-day-old embryos and only in occasional cells of 7- and 8-day-old embryos. No 5'-nucleotidase activity could be demonstrated in 6- to 8-day-old cylinders. There was marked ATPase and 5'-nucleotidase activity in the membranes of embryonal carcinoma cells. These data point out some differences on the plasma membrane between the embryonal carcinoma cells and equivalent embryonic cells. The potential significance of these differences is discussed with regards to the transformation of embryonic cells in tumor cells. (Am J Pathol 87:297-310, 1977).
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PMID:Ultrastructural localization of membrane phosphatases in teratocarcinoma and early embryos. 19 83

A comparative study of glucose-6-phosphatase, alcaline RNase, ATPase, inosine diphosphatase and 5'-nucleotidase activities in isolated rat liver and hepatoma-27 nuclei and nuclear envelopes was performed. The tumor nuclear membranes were shown to be free from G-6-Pase activity in contrast to the liver nuclear membranes. The nuclear RNase activity was strongly inhibited in the hepatoma and could be unmasked in the presence of 3-10(-4) M pCMB. Hepatoma nuclear and nuclear envelopes ATP-ase activity was found to be moderately decreased as compared to those of the normal tissue. The values of inosine diphosphatase activity in hepatoma were similar to those in liver. The role of the nuclear envelope in nuclear-cytoplasmic interactions as well as nuclear location of G-6-Pase are discussed.
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PMID:[Various enzymes of isolated nuclear membranes and cell nuclei of the liver and hepatoma 27 of rats]. 19 29

Cell division is induced in stationary cultures of BALB/c-3T3 mouse embryo cells without renewal of medium by addition of the tumor promoter, phorbol myristate acetate (PMA), or bovine serum. The addition of dbcAMP (10(-3) M) or other inhibitors of cAMP phosphodiesterase, papaverine (6.7 X 10(-6) M), Persantin (5 X 10(-5) M) or RO-20-1724 (10(-4) M), prevents cell replication induced by PMA or serum. In contrast, ouabain (10(-4) M) and N,N'-dicyclohexylcarbodiimide (10(-5) M), inhibitors of Na+-K+-ATPase activity, block the PMA-stimulated effect but do not inhibit serum-stimulated cell division. Several stages in the cell cycle are sensitive to dbcAMP addition. One is early in the G1 phase at the time of reinitiation of the cell cycle from a stationary (Go) phase, a second is associated with the G1-S transition, and a third with passage of cells from a post-S phase to mitosis. Based on observations of early morphological changes, responses of plasma membrane enzymes and effects of enzyme inhibitors, the stimulation of cell division in BALB/c-3T3 cells by PMA or serum appears to involve several membrane functions which may act in a cooperative manner.
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PMID:Induction of cell division in BALB/c-3T3 cells by phorbol myristate acetate or bovine serum: effects of inhibitors of cyclic AMP phosphodiesterase and Na+-K+-ATPase. 19 94

SV40 T-antigen was isolated from hamster tumors and purified about 1600-fold by the procedure including successive ammonium sulfate precipitation, chromatography on DEAE-cellulose, preparative polyacrylamide gel electrophoresis and elimination of the bulk of contaminating cell proteins by the interaction with antibodies to the tissues of normal hamsters. The resulting preparation was not quite homogenous being contaminated with some of cell proteins left. T-antigen in the tumor extract was revealed at least in three distinct forms with molecular weight of 100 000, 200 000, and 400 000. It is proposed that these forms correspond to mono-, di-, and tetramers of the basal protein of T-antigen, although the alternative explanation, the existence of complex of T-antigen with cell proteins, cannot be ruled out.
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PMID:[Preparative isolation and some properties of SV40 T-antigen]. 19 85

Using electrophysiological techniques we have examined the apical membrane ionic permeabilities of primary cell cultures of the mouse mammary gland in the midpregnant, preneoplastic, and neoplastic states. Membrane Na+ permeability changed with tumorigenesis, whereas K+ and Cl- permeabilities were unaltered. With tracer flux techniques the unidirectional efflux rate constant of 22Na was found to be greater in tumor cells than it is in normal cells. This increase in 22Na efflux was eliminated by the addition of ouabain. The results are interpreted as an increase in Na+ permeability and in Na+-K+-ATPase activity with the neoplastic transformation. The presence or absence of the virus in midpregnant cells does not seem to affect Na+ permeability.
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PMID:Alteration of sodium transport in mouse mammary epithelium associated with neoplastic transformation. 20 64


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