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

Poly(A) polymerase was extracted from isolated nuclei of rat liver and a rapidly growing solid tumor (Morris hepatoma 3924A). The enzyme from each tissue was purified by successive chromatography on DEAE-Sephadex, phosphoecllulose, hydroxyapatite and QAE-Sephadex. Purified enzyme from both liver and tumor was essentially homogeneous as judged by polyacrylamide gel electrophoresis. Under nondenaturing conditions, enzyme activity corresponded to visible protein and, upon denaturation, a single polypeptide was detected. The enzymes had absolute requirements for Mn2+ as the divalent ion, ATP as the substrate and an oligonucleotide or polynucleotide as the primer. Both enzymes were inhibited by sodium pyrophosphate, N-ethylmaleimide, Rose Bengal, cordycepin 5'-triphosphate and several rifamycin derivatives. The reactions were unaffected by potassium phosphate, alpha-amanitin and pancreatic ribonuclease. However, the liver and hepatoma enzymes differed from each other with respect to apparent Km, primer saturation levels and sensitivity to pH changes. The most striking differences between the enzymes were in their calculated molecular weights (liver, 48000; hepatoma, 60000) and amino acid compositions. Finally, the level of the hepatoma enzyme relative to that of the liver enzyme was at least 1.5-fold higher when expressed per mg DNA.
 ...
PMID:Nuclear poly(A) polymerase from rat liver and a hepatoma. Comparison of properties, molecular weights and amino acid compositions. 18 50

Leucocidin, one of the cytotoxic principles of Pseudomonas aeruginosa induces potassium loss and swelling in isolated hepatocytes and in AS-30D ascites hepatoma cells in a dose and time dependent manner. Hepatoma cells are more sensitive than normal hepatocytes. As shown by scanning electron microscopy the volume increase of both types of cells is accompanied by disappearance of microvilli. In contrast to phalloidin poisoning no protrusions were formed when the cells were exposed to leucocidin under isotonic conditions.
 ...
PMID:Comparative studies on isolated rat hepatocytes and AS-30D hepatoma cells with leucocidin from Pseudomonas aeruginosa. 18 64

The suitability for field use of heating up to 80 degrees C and adding six different virucidal chemicals for decontamination of drinking and surface water was investigated using the viruses of Polio (vaccine strain), ECBO, Reo, bovine Parvo, HCC, Pseudorabies, ND and Vaccinia. The Parvovirus (concentration 10(5) TCID50/ml) heated to 80 degrees C could not be inactivated completely in drinking water within one hour; the Reovirus could after one hour only at 60 degrees C. The other viruses used lost their infectivity at 56 degrees C within 60 minutes or at 60 degrees C within 20 minutes respectively. Heating therefore seems to be too circumstantial a method for viral decontamination of water and unreliable under field conditions. As to the chemical water additives tested, chloramine-T, hydrogen peroxide and sodium peroxide proved to be unsuitable in spite of virucidal activity. The amount of their concentration necessary for reliable virus inactivation makes the water unfit for drinking. Iodine, a calcium hypochlorite sample and potassium permanganate were useful. Because of its constant reaction in drinking water together with additional advantages, iodination of water would seem to be the best method at present for viral water decontamination usable under field conditions.
 ...
PMID:[Studies on inactivation of viruses in drinking and surface water. A contribution to the decontamination of water by field methods (author's transl)]. 61 Feb 55

A patient with an angiosarcoma of the liver associated with the chronic ingestion of Fowler's solution (potassium arsenite) is described. The patient's clinical course was characterized by upper gastrointestinal hemorrhage, recurrent hemoperitoneum, hepatic failure, and, subsequently, the appearance of an angiosarcoma of the skin. Selective angiography demonstrated features consistent with both hepatoma and cavernous hemangioma. The hepatic toxicity and the carcinogenicity of arsenic are reviewed, with particular reference to Fowler's solution, which previously has been widely used for the treatment of psoriasis. The long latency period for the development of the malignancies is emphasized.
 ...
PMID:Angiosarcoma of the liver associated with Fowler's solution (potassium arsenite). 116 81

MH1C1, HTC and HEPA 1c1c7 hepatoma cell lines were selected in this study as the bioindicators of the cytotoxicity induced by six chemicals: butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), cycloheximide (CHE), cyclophosphamide (CPA), potassium dichromate (Cr VI) and 2,4-dinitrophenol (DNP). The concentrations used were in the range from 10(-6) mol/l to 10(-2) mol/l, and the exposure time was 24 h. Two end-points were measured to evaluate cytotoxicity: the detachment of dead cells from the monolayer (CS), as evaluated by detection of the total macromolecules present in the cell monolayers solubilized in alkali and the loss of colony-forming efficiency (CF). The dose-response curves were different from one compound to another, but generally similar with the two assays, the colony formation being the most sensitive test. Some technical problems like the toxicity of the solvents at the highest concentrations, the different sizes of colonies, the unspecific cellular detachment due to overgrowth during the experimental time, can be overcome by accurate standardization of the protocols used for each cell line. The sensitivity of the three cell lines was very similar, with some differences in the case of compounds exerting intermediate toxic effects, like CHE and DNP. The most toxic compound was Cr (VI), the least toxic one was CPA. The low cytotoxic effects displayed by CPA could be due to a lack of bioactivation and/or an increase of the inactivating enzymes, which are typical of hepatoma cell lines.
 ...
PMID:Comparative assessment of the cytotoxic effects of different xenobiotics in three hepatoma cell lines. 141 81

Biochemical and morphological studies compared the ATP requirements for and the internalization routes of alpha 2-macroglobulin and insulin in H35 hepatoma cells. Cellular ATP concentrations were decreased more than 94% by 1 mM 2,4-dinitrophenol or 10 mM sodium azide, potassium cyanide, or oligomycin. ATP depletion decreased total cell-associated alpha 2-macroglobulin 70-90% by inhibiting binding 67-77% and receptor-mediated internalization 90-96%. Under the same conditions, insulin binding was decreased less than 10%, and endocytosis and intracellular accumulation were not affected. Quantitative electron microscopic analysis of the distribution of occupied receptors on the surface of control and treated cells was performed using colloidal gold-labeled alpha 2-macroglobulin or insulin. alpha 2-Macroglobulin concentrated in and was internalized almost exclusively by coated pits. Insulin was rarely associated with coated pits, but was found in and internalized by noncoated invaginations. ATP depletion did not affect receptor mobility or ligand-induced aggregation of either receptor. There was an increase in the amount of alpha 2-macroglobulin found in coated pit-like structures. The coat underlying pits in ATP-depleted cells was poorly defined and may account for the inability of coated pits to form and/or internalize. These results showed that receptor-mediated internalization via coated pits was ATP dependent, whereas internalization via pinocytotic invaginations was energy independent, which explained the difference in the ATP dependency of uptake for the two ligands. These observations suggested that autophosphorylation of the insulin receptor may not be involved in either the aggregation or internalization of the insulin-receptor complex, since ATP depletion did not affect either process. This study provided evidence that specialized mechanisms exist for the internalization of insulin which may be related to some of its intracellular effects.
 ...
PMID:Differences in adenosine triphosphate dependency of receptor-mediated endocytosis of alpha 2-macroglobulin and insulin correlate with separate routes of ligand-receptor complex internalization. 168 53

Alkaline phosphatase activity in rat hepatoma cells (R-Y121B) cultured in a monolayer at 0.5% serum was enhanced by serum, bovine serum albumin, casein and gamma-globulin, but ovalbumin, polyvinylpyrrolidone, dexamethasone, insulin and dibutyrylcyclic AMP showed little effect on alkaline phosphatase activity. In addition, cycloheximide, actinomycin D, chloroquine, dinitrophenol and potassium cyanide also increased the enzyme activity, although the incorporation of [14C]leucine into cellular proteins was almost completely inhibited in the presence of these cytotoxic substances. When R-Y121B cell homogenates were incubated at 37 degrees C, alkaline phosphatase activity increased in a pH-dependent manner: the maximal increase was observed at pH 7.1. The magnitudes of the increase differed among cell homogenates and a 4- to 10-fold increase was observed. Alkaline phosphatase in R-Y121B cells was apparently heat-stable, but that in the cells obtained from various treatments was heat labile and the latter activity decreased to less than 50% of the initial activity after 15 min of incubation at 56 degrees C. Alkaline phosphatase in the control and also in the treated cells was more sensitive to L-homoarginine than L-phenylalanine. The Lineweaver-Burk plot showed that the increases in the enzyme activity were accompanied by changes not only in V but also in Km for alkaline phosphatase reaction. Finally, it has been suggested that the increases in alkaline phosphatase activity under various conditions are due to the conversion of the molecule with a low enzyme activity to the molecule with a high enzyme activity in R-Y121B cells.
 ...
PMID:Regulation of alkaline phosphatase activity in rat hepatoma cells. Effects of serum proteins, cycloheximide, actinomycin D, chloroquine, dinitrophenol and potassium cyanide. 241 85

A sphingomyelinase, which specifically hydrolyzes sphingomyelin into ceramide and phosphocholine, was solubilized from nuclear matrix fraction of rat ascites hepatoma, AH7974 cells. The solubilized enzyme was subjected to Mono Q column chromatography in an FPLC system. The sphingomyelinase which was adsorbed on the column and eluted at 0.25-0.5 M NaCl was characterized. The enzyme required 10 mM MgCl2, 0.01% Triton X-100, 1 mM dithiothreitol, and a higher concentration of buffer than 1 M for its maximal activity, and the optimal pH was 6.7-7.2 in 2 M Tris/acetic acid or 7.5 in 2 M potassium acetate/acetic acid. N-Ethylmaleimide completely inhibited the enzyme activity at 0.2 mM. Therefore, this enzyme is classified as a Mg2+-dependent, neutral sphingomyelinase. The sphingomyelinase sedimented at 4.3S through a 10-30% glycerol gradient containing 2 M potassium acetate. This enzyme was highly specific to sphingomyelin and did not hydrolyze phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol. Various characteristics of the nuclear sphingomyelinase were similar to those of the plasma membrane enzyme except its requirement for a high concentration of buffer and SH-reagent.
 ...
PMID:Existence of Mg2+-dependent, neutral sphingomyelinase in nuclei of rat ascites hepatoma cells. 255 12

Purified plasma membrane fractions of cultured well-differentiated Reuber H35 hepatoma cells were studied after growth in the presence or absence of ethanol. Growth of cells in the presence of ethanol significantly increased plasma membrane 5'-nucleotidase activity but did not influence sodium-potassium adenosinetriphosphatase activity. Fluorescence polarization of lipophilic probes was used to study membrane lipid structure. Steady-state polarization of diphenylhexatriene (DPH), a probe of the hydrophobic core, was significantly lower in plasma membranes from cells grown in 80 mM ethanol for 3 weeks, compared to controls. Decreased polarization of DPH in plasma membranes was observed after 3-weeks growth of cells in as little as 1 mM ethanol. A 1-h exposure to 80 mM ethanol had no effect. Altered DPH polarization was due to a decrease in the order parameter of the probe. The rotational correlation time of the probe was virtually unchanged. Chronic ethanol treatment of cells did not alter the polarization of the membrane surface probe trimethylammoniodiphenylhexatriene. Plasma membranes from cells grown in 80 mM ethanol had decreased contents of both phospholipid and unesterified cholesterol, but the cholesterol to phospholipid ratio was unchanged. The percentages of sphingomyelin and phosphatidylserine in plasma membrane phospholipids were significantly decreased after ethanol treatment, while the phosphatidylcholine/sphingomyelin ratio was increased by 42%. Vesicles prepared from total plasma membrane lipids of ethanol-treated cells, as well as vesicles prepared from polar lipids alone, showed the same alterations in DPH polarization as did plasma membranes. The importance of ethanol metabolism in the observed plasma membrane changes was demonstrated in two ways.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Chronic ethanol increases liver plasma membrane fluidity. 402 34

1. The sedimentation pattern of Yoshida hepatoma ribosomes shows mainly a high dimer peak and an intermediate peak between those of monomer and dimer. 2. The treatment of the postmitochondrial supernatant with EDTA or potassium chloride leads to the dissociation of ribosomes into subunits, through a decrease ofthe ribosomal Mg(2+)/phosphorus ratio. Provided that the deprivation of endogenous Mg(2+) is not complete, the subunits reassociate into active polyribosomes after addition of magnesium chloride to the medium. If the Mg(2+)/phosphorus ratio is lowered below 0.01 (mumol/mumol), structural changes occur, that become evident by a loss of protein and by a decreased sedimentation rate, which render the subribosomal particles unable to reassociate. 3. In the re-formation of polyribosomes from subunits, during the progressive increase of the concentration of magnesium chloride in the medium, the formation of monomeric ribosomes seems to be intermediate. 4. A dimerization of monomers and subunits occurs at concentrations of magnesium chloride greater than those required for the re-formation of polyribosomes and a preincubation for 1h at 0 degrees C is necessary for the maximum dimerization, whereas the complete reconstitution of polyribosomes is immediate.
 ...
PMID:The dissociation of Yoshida hepatoma ribosomes into active particles. 433 51


1 2 3 4 5 6 7 8 9 Next >>