Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The stability of nine viruses, Aujeszky, Sindbis, Vesicular Stomatitis, Newcastle Disease, Vaccinia, FMD, HCC, Reo and Teschen virus in drinking and surface water was investigated comparatively at temperatures of 9 and 15 degrees C as well as the influence of water factors like seasonal difference in temperature, pH value, hardness and sort of water. The results can be summarized as follows: 1. At temperatures of 9 to 15 degrees C the majority of the viruses remained stabil in natural water for an astonishing long time. 2. Starting with virus concentration of about 10(4) infectious units per ml Teschen, Vaccinia, Reo, HCC and ND virus could mostly be demonstrated in water longer than 200 days and FMD, Aujeszky, Vesicular Stomatitis and Sindbis virus for 20 to 50 days on average at 9 degrees C. The stability of the viruses investigated decreased in water in the named turn. 3. Based on these results it can be assumed that under natural conditions with very low virus content of some particles the labile viruses such as Toga, Herpes, Rhabdo and pH labile Picorna remain infectious in water for some days. They should not have any importance as water contaminants. More resistant viruses like Paramyxo may keep infectious for weeks and very stabile viruses such as Entero, Reo, Adeno and Pox viruses several weeks to months. 4. As to factors temperature, pH, hardness and sort of water-within the naturally differing range-only the temperature and only in the case of less resistant viruses showed significant influence on the virus stability in water.
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PMID:[Stability in drinking and surface water of nine virus species from different genera (author's transl)]. 1 60

The acceptor activities of subcellular membrane preparations for the terminal sugars, galactose and sialic acid, were compared using a Golgi fraction purified from rat liver as an exogenous emzymes source for sugar transfer. Data are presented which strongly suggest that completion of carbohydrate chains of membrane glycoproteins and glycolipids occurs in the Golgi apparatus. Significant differences of acceptability of galactose and sialic acid were found between plasma membranes of rat liver and hepatoma cells (AH-130), indicating "incompleteness" of sugar chains in the latter.
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PMID:Acceptor activity of subcellular membranes for two terminal sugars, galactose and sialic acid. 1 42

Concanavalin A added to intact cells at 37 degrees caused rapid and reversible inactivation of a soluble enzyme, tyrosine aminotransferase, in two lines of rat hepatoma tissue culture cells grown in monolayer culture. This temperature-dependent process was independent of de novo protein and RNA synthesis and independent of increased uptake of Ca2+ and Mg2+ or glucose. The inactivation could be reversed by adding alpha-methyl-D-mannopyranoside a competing sugar for concanavalin A binding. Other lectins known to bind to different sugars did not bring about the inactivation of tyrosine aminotransferase. Addition of concanavalin A did not result in the inactivation of another soluble enzyme, lactic dehydrogenase. The maintenance of tyrosine aminotransferase in an inactive form after the binding of concanavalin A to the cells required the continued presence of concanavalin A. This effect of concanavalin A could not be mimicked either by dibutyryl cyclic adenosine or guanosine monophosphoric acid. Incubation of cell extracts with concanavalin A did not result in inactivation nor did mixing of extracts from concanavalin A-treated cells with extracts from untreated cells. On the basis of these results we conclude that the following are the essential requirements for concanavalin A to bring about the inactivation of tyrosine aminotransferase: (a) the binding of native concanavalin A to the cells; (b) integrity of certain structural elements of the cells.
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PMID:Effect of concanavalin A on tyrosine aminotransferase in rat hepatoma tissue culture cells. Rapid reversible inactivation of soluble enzyme. 1 97

Amino acid starvation causes an adaptive increase in the initial rate of transport of selected neutral amino acids in an established line of rat hepatoma cells in tissue culture. After a lag of 30 min, the initial rate of transport of alpha-aminoisobutyric acid (AIB) increases to a maximum after 4 to 6 h starvation of 2 to 3 times that seen in control cells. The increased rate of transport is accompanied by an increase in the Vmax and a modest decrease in the Km for this transport system, and is reversed by readdition of amino acids. The enhancement is specific for amino acids transported by the A or alanine-preferring system (AIB, glycine, proline); uptake of amino acids transported by the L or leucine-preferring system (threonine, phenylalanine, tyrosine, leucine) or the Ly+ system for dibasci amino acids (lysine) is decreased under these conditions. Amino acids which compete with AIB for transport also prevent the starvation-induced increase in AIB transport; amino acids which do not compete fail to prevent the enhancement. Paradoxically threonine, phenylalanine, tryptophan, and tyrosine, which do not compete with AIB for transport, block the enhancement of transport upon amino acid starvation. The starvation-induced enhancement of amino acid transport does not appear to be the result of a release from transinhibition. After 30 min of amino acid starvation, AIB transport is either unchanged or slightly decreased even though amino acid pools are already depleted. Furthermore, loading cells with high concentrations of a single amino acid following a period of amino acid starvation fails to prevent the enhancement of AIB transport, whereas incubation of the cells with the single amino acid for the entire duration of amino acid starvation prevents the enhancement; intracellular amino acid pools are similar under both conditions. The enhancement of amino acid transport requires concomitant RNA and protein synthesis, consistent with the view that the adaptive increase reflects an increased amount of a rate-limiting protein involved in the transport process. Dexamethasone, which dramatically inhibits AIB transport in cells incubated in amino acid-containing medium, both blocks the starvation-induced increase in AIB transport, and causes a time-dependent decrease in transport velocity in cells whose transport has previously been enhanced by starvation.
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PMID:Derepression of amino acid transport by amino acid starvation in rat hepatoma cells. 1 7

The increase in tyrosine aminotransferase activity which occurs in rat hepatoma tissue culture (HTC) cells in response to cyclic AMP analogs has been shown to be an enzyme induction, similar to the larger response observed in certain other hepatoma cells and in liver. A specific antibody to tyrosine aminotransferase has been used to show that the number of enzyme molecules and the rate of enzyme synthesis are increased by N6,O2'-dibutyryl cyclic AMP in HTC cells. The effect on tyrosine aminotransferase is also produced by various 8-substituted derivatives of cyclic AMP and occurs whether or not the enzyme has been preinduced with a glucocorticoid. The response of the enzyme is greater when HTC cells are maintained in monolayer than in suspension cultures. Neither cell growth nor serum is required for the response.
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PMID:The influence of culture conditions on the induction of tyrosine aminotransferase by cyclic nucleotides in rat hepatoma cells. 1 19

Reproducible induction of the enzyme tyrosine aminotransferase by dibutyryl cAMP (Bt2cAMP) in a line of HTC hepatoma cells in suspension culture requires that the cells be preinduced with dexamethasone, a synthetic glucocorticoid which itself induces tyrosine aminotransferase. Concentrations of dexamethasone that do not induce tyrosine aminotransferase fail to support Bt2cAMP induction, removal of the steroid from the medium leads to a loss of the Bt2cAMP effect, and an HTC cell line whose aminotransferase is not steroid-inducible does not respond to the cyclic nucleotide. We show that the further induction of tyrosine aminotransferase by Bt2cAMP in dexamethasone-treated cells is due to an increased rate of enzyme synthesis. The cyclic nucleotide has no effect on aminotransferase synthesis in cells grown in the absence of steroid. Several lines of evidence suggest that dexamethasone acts at a step beyond the activation of protein kinase by cAMP: (a) basal levels of cAMP are not altered by growth of HTC cells in dexamethasone; (b) accumulation of cAMP from the medium is not enhanced; (c) the glucocorticoid does not induce cAMP-dependent protein kinase in HTC cells; and (d) there is no augmentation of cAMP binding to the regulatory protein, nor is there any change in cAMP activation of protein kinase caused by growth in dexamethasone. These results help define a system that should be useful in studying the interaction of cyclic nucleotides and steroid hormones.
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PMID:Interaction of glucocorticoid hormones and cyclic nucleotides in induction of tyrosine aminotransferase in cultured hepatoma cells. 1 22

Reuber (H35) hepatoma cells were grown in medium containing 10(-5)M bromodeoxyuridine (BrdU), which was incorporated into their DNA. Cell growth rate was unaffected by BrdU for the first two generations, after which it was reduced by about 50%. The effect of BrdU incorporation on the activities of several enzymes with rapid turnover rates was examined to test the hypothesis that the synthesis of such enzymes will be preferentially inhibited by BrdU. Tyrosine amino-transferase (TAT) activity decreased by 70% within two generations whereas thymidine kinase activity remained at control values. PEP carboxykinase activity was unchanged during the first generation in BrdU-containing medium but, during the second, its activity increased by at least 30%. Ornithine decarboxylase levels decreased by about 50% only after two generations in the presence of BrdU. There appeared to be no simple relationship between turnover rates and the effect of BrdU on enzyme activity. Incorporation of BrdU was found to inhibit the induction of both TAT and PEP carboxykinase by dexamethasone and to enhance the inhibition of cell growth by this steroid. These results are discussed with respect to possible mechanisms of gene expression and development in both normal and neoplastic cells.
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PMID:The diverse effects of 5'-bromodeoxyuridine on enzyme activities in cultured H35 hepatoma cells. 1 36

The effect(s) of lack of dietary pyridoxine (PX) on the growth of Morris hepatoma no. 7288Ctc was studied. Buffalo strain female rats were fed a diet lacking PX. Pair-fed controls were fed the same diet with PX added. Animals were inoculated with no. 7288Ctc hepatoma cells at 21 days and were sacrificed 16 days later. Host livers and tumors were removed, weights recorded and the activity of tyrosine aminotransferase (TAT; L-tyrosine: 2-oxoglutarate aminotransferase, EC 2.6.1.5) was determined in both host liver and hepatoma. The average weight of 30 hepatomas grown in pair-fed control rats was 11.61 +/- 1.5 g while the average weight of the same number of hepatomas grown in animals fed the PX free diet was 4.73 +/- 0.7 g (P less than 0.001). Further TAT specific activity levels were 39% and 32% higher in host livers and tumors from deficient animals, respectively. The results show that availability of dietary pyridoxine stimulates the growth of this hepatoma and, in addition, exercises a type of control over the expression of TAT activity.
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PMID:Effect of pyridoxine on the growth of Morris hepatoma No. 7288Ctc and enzyme activity. 1 84

Most of the hybrid clones derived from a cross of Chinese hamster fibroblasts (DON) with rat hepatoma cells (Faza 967) showed preferential loss of rat chromosomes. Two of the hybrid clones retained the rat chromosomes, and both showed extinction of 4 liver-specific enzymes: aldolase B, liver alcohol dehydrogenase, and the inducible enzymes tyrosine aminotransferase and alanine aminotransferase. Subcloning of 1 of these hybrids, which contained 2 sets of hepatoma chromosomes and 1 set of hamster chromosomes, permitted the isolation of some clones which reexpressed 1 or more of the liver-specific enzymes. Liver alcohol dehydrogenase was the most frequently reexpressed enzyme and aldolase B the least. Tyrosine aminotransferase inducibility was reexpressed independently of basal activity, and the enzyme produced by the reexpressing hybrid cells was precipitated by a specific antiserum. No correlation was detected between the presence or absence of the marker chromosomes (large metacentrics) of the hamster parent and the extinction and reexpression of the hepatic enzymes. The results reported confirm and extend to interspecific hybrids the observation of the stable and independent reexpression of tissue-specific enzymes.
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PMID:Expression of differentiated functions in hepatoma cell hybrids: IX extinction and reexpression of liver-specific enzymes in rat hepatoma-Chinese hamster fibroblast hybrids. 1 64

A cross has been performed between dedifferentiated rat hepatoma cells and the differentiated cells from which they were derived. 10 hybrid clones, containing the complete chromosome sets of both parents, show extinction of 4 liver-specific enzymes: tyrosine aminotransferase (E.C. 2.6.1.5), alanine aminotransferase (E.C. 2.6.1.2), and the liver-specific isozymes of alcohol dehydrogenase (E.C. 1.1.1.1) and aldolase (E.C. 4.1.2.13). Moreover, the 4 hybrid clones examined do not produce albumin . The only function of the differentiated parent which is not extinguished in the hybrid cells is inducibility of the aminotransferases. For 3 of the hybrid clones, extinction of 3 of the 4 enzymes is incomplete, but these clones do not differ in modal chromosome number from those which show more complete extinction of the enzymes. Subcloning of several of the hybrids revealed that the phenotype of the hybrids is very stable; 4 subclones showing reexpression of intermediate levels of the enzymes are characterized. These results show that dedifferentiation of the parental cells is not due to the simple loss of some factor required for the maintenance of expression of differentiated functions, and suggest that dedifferentiation is due to the activation of some control mechanism, whose final effect is negative, and which may be a part of the epigenotype of the embryonic hepatocyte.
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PMID:Extinction of liver-specific functions in hybrids between differentiated and dedifferentiated rat hepatoma cells. 1 65


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