Search results for "Tumor cell"

A bioactive designer cytokine for human hematopoietic progenitor cell expansion

1997

Efficient expansion of hematopoietic progenitor cells requires, at least, the simultaneous stimulation of the receptors c-kit and gp130. While c-kit is activated by SCF; gp130, in cells which do not express sufficient amounts of IL-6R, can be activated by the complex of soluble IL-6R (sIL-6R) and IL-6. The therapeutic use of IL-6/sIL-6R, however, has been hampered by the high concentrations of the sIL-6R protein required. We have designed a fusion protein of sIL-6R and IL-6, linked by a flexible peptide chain, that was expressed to high levels. On gp130 expressing cells the fusion protein turned out to be fully active at 100 to 1,000-fold lower concentration than the combination of unlinked…

Stimulation of peroxisomal palmitoyl-CoA oxidase activity by ciprofibrate in hepatic cell lines: comparative studies in Fao, MH1C1 and HepG2 cells.

1993

The response of two rat cell lines, Fao and MH1C1, and one human cell line, HepG2, to the peroxisome proliferator ciprofibrate, was studied. Using a fluorometric assay for palmitoyl-CoA oxidase, the dose- and time-dependent increase of this enzymatic activity was determined. From the lowest concentration (100 microM) stimulation is evident in the two rat cell lines. In the Fao line, the activity was stimulated reaching a seven-fold increase over the control level at 250 microM after 72 h of treatment. In the MH1C1 line, the maximum stimulation, four- to five-fold, was obtained at 250 and 500 microM after 72 h. In the HepG2 cell line, activity increased two-fold at 250 microM after 72 h reac…

Novel cell culture systems for the hepatitis C virus.

2001

Infections with the hepatitis C virus (HCV) are a major cause of acute and chronic liver disease. The high prevalence of the virus, the insidious course of the disease and the poor prognosis for long-term persistent infection make this pathogen a serious medical and socioeconomical problem. The identification of the viral genome approximately 10 years ago rapidly led to the delineation of the genomic organization and the structural and biochemical characterization of several virus proteins. However, studies of the viral life cycle as well as the development of antiviral drugs have been difficult because of the lack of a robust and reliable cell culture system. Numerous attempts have been un…

Replication of subgenomic hepatitis C virus RNAs in a hepatoma cell line.

1999

An estimated 170 million persons worldwide are infected with hepatitis C virus (HCV), a major cause of chronic liver disease. Despite increasing knowledge of genome structure and individual viral proteins, studies on virus replication and pathogenesis have been hampered by the lack of reliable and efficient cell culture systems. A full-length consensus genome was cloned from viral RNA isolated from an infected human liver and used to construct subgenomic selectable replicons. Upon transfection into a human hepatoma cell line, these RNAs were found to replicate to high levels, permitting metabolic radiolabeling of viral RNA and proteins. This work defines the structure of HCV replicons funct…

Toxicity of waste gasification bottom ash leachate

2011

Abstract Toxicity of waste gasification bottom ash leachate from landfill lysimeters (112 m3) was studied over three years. The leachate of grate incineration bottom ash from a parallel setup was used as reference material. Three aquatic organisms (bioluminescent bacteria, green algae and water flea) were used to study acute toxicity. In addition, an ethoxyresorufin-O-deethylase (EROD) assay was performed with mouse hepatoma cells to indicate the presence of organic contaminants. Concentrations of 14 elements and 15 PAH compounds were determined to characterise leachate. Gasification ash leachate had a high pH (9.2–12.4) and assays with and without pH adjustment to neutral were used. Gasifi…

Loss of response of carnitine palmitoyltransferase I to okadaic acid in transformed hepatic cells

1998

The specific activity of carnitine palmitoyltransferase I (CPT-I) was similar in mitochondria isolated from rat Fao and human HepG2 hepatoma cells and from rat hepatocytes, but almost twofold higher in permeabilized hepatoma cells than in permeabilized hepatocytes. Short-term exposure to okadaic acid induced a ca. 80% stimulation of CPT-I in hepatocytes, whereas no significant response of the enzyme from hepatoma cells was evident. Thus, the high CPT-I activity displayed by hepatoma cells may be reached by hepatocytes upon challenge to okadaic acid. Reconstitution experiments with purified mitochondrial and cytoskeletal fractions showed that the cytoskeleton of hepatocytes produced a more r…

Electrophoresis of Unlabeled Proteins in a Sequencing Gel Apparatus

2000

Allogeneic effector/memory Th-1 cells impair FoxP3+ regulatory T lymphocytes and synergize with chaperone-rich cell lysate vaccine to treat leukemia

2011

AbstractTherapeutic strategies combining the induction of effective antitumor immunity with the inhibition of the mechanisms of tumor-induced immunosuppression represent a key objective in cancer immunotherapy. Herein we demonstrate that effector/memory CD4+ T helper-1 (Th-1) lymphocytes, in addition to polarizing type-1 antitumor immune responses, impair tumor-induced CD4+CD25+FoxP3+ regulatory T lymphocyte (Treg) immunosuppressive function in vitro and in vivo. Th-1 cells also inhibit the generation of FoxP3+ Tregs from naive CD4+CD25−FoxP3− T cells by an interferon-γ–dependent mechanism. In addition, in an aggressive mouse leukemia model (12B1), Th-1 lymphocytes act synergistically with …

Characterization of a nuclear localization signal of canine parvovirus capsid proteins.

1998

We investigated the abilities of synthetic peptides mimicking the potential nuclear localization signal of canine parvovirus (CPV) capsid proteins to translocate a carrier protein to the nucleus following microinjection into the cytoplasm of A72 cells. Possible nuclear localization sequences were chosen for synthesis from CPV capsid protein sequences (VP1, VP2) on the basis of the presence of clustered basic residues, which is a common theme in most of the previously identified targeting peptides. Nuclear targeting activity was found within the N-terminal residues 4-13 (PAKRARRGYK) of the VP1 capsid protein. While replacement of Arg10 with glycine did not affect the activity, replacement of…

Induction of apoptosis by arachidonic acid in human retinoblastoma Y79 cells: involvement of oxidative stress

2000

Arachidonic acid administration caused apoptosis in Y79 cells, as shown by typical morphological changes, phosphatidylserine externalization, chromatin condensation, processing and activation of caspase-3 and cleavage of the endogenous caspase substrate poly-(ADP-ribose)-polymerase. Arachidonic acid also caused lamin B cleavage, suggesting caspase-6 activation. Arachidonic acid treatment was accompanied by increased formation of the lipid peroxidation end products malondialdehyde and 4-hydroxy-2-nonenal, lowering in reduced glutathione content and in mitochondrial membrane potential. Inhibiting glutathione synthesis sensitized Y79 cells to apoptosis-inducing stimuli, whilst replenishing red…