Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Life and Medical Sciences  (17)
  • Chemotherapy  (1)
  • Exotoxin  (1)
  • 1
    ISSN: 1476-5535
    Keywords: Epidermal growth factor ; Exotoxin ; Cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Transforming growth factor-alpha (TGFα)-pseudomonas exotoxin-40 (PE40) is a chimeric protein consisting of an N-terminal TGFα domain fused to a C-terminal 40-kDa segment of the pseudomonas exotoxin A protein. TGFα-PE40 exhibits the receptor binding activity of TGFα and the cell killing activity of PE40. In the current study, we report that a modified TGFα-PE40 derivative significantly prolongs the survival of nude mice bearing tumors derived from cell lines which express the epidermal growth factor receptor (EGFR). In addition, the therapeutic benefit of this protein is mediated by specific binding to the EGF receptor. These results indicate that a therapeutic window exists in vivo for the use of some growth factor-toxin fusion proteins as anticancer agents.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1573-6881
    Keywords: Chemotherapy ; ATP ; drug transport ; colchicine ; actinomycin D ; doxorubicin ; vinblastine ; vincristine ; introns ; evolution ; P-glycoprotein ; transmembrane domains ; MDR1 gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Multidrug resistance in animal cells is defined as the simultaneous resistance to a variety of compounds which appear to be structurally and mechanistically unrelated. One type of multidrug resistance is characterized by the decreased accumulation of hydrophobic natural product drugs, a phenotype which is mediated by an ATP-dependent integral membrane multidrug transporter termed P-glycoprotein or P170. The gene coding for P170 is calledMDR. The nucleotide-binding domain of P-glycoprotein shares sequence homology with a family of bacterial permease ATP-binding components. In addition, P170 as a whole is structurally very similar to a number of prokaryotic and eukaryotic proteins believed to be involved in transport activities. This review summarizes our current knowledge of the molecular biology and clinical significance ofMDR expression and P-glycoprotein transport activity, as well as some theories about the function of this protein in normal cells.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0730-2312
    Keywords: cell transformation ; neoplastic ; receptor ; epidermal growth factor ; transforming growth factor ; oncogenes ; genetic vectors ; retrovirus ; bioassay ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Two retroviral DNAs that encode the normal human epidermal growth factor (EGF) receptor hEGFR have been generated by inserting a hEGFR cDNA into two different retroviral vectors. One DNA (pCO11-EGFR-neo) also contained a linked selectable marker gene (neoR). The other (pCO12-EGFR) only expresses hEGFR. When introduced into NIH3T3 cells, the two DNAs and the viruses derived from them induced a fully transformed phenotype, including focal transformation and growth in agar or low serum, but transformation depended entirely upon EGF being present in the growth medium. Compared with pCO11-EGFR-neo, pCO12-EGFR induced EGF-dependent transformation 2-5 times more efficiently and expressed higher numbers of receptors (4 × 105 vs. 1 × 105 EGF receptors per cell). The results indicate that transforming potential is directly related to the number of EGF receptors. In defined, serum-free medium that contained only very low concentrations of insulin (0.6 μg/ml) and transferrin (0.6 μg/ml), hEGFR-virus infected cells were able to grow with EGF as the only growth factor. Moreover, daily incubation of the cells with EGF for only 30 min was sufficient to induce growth. NR6 cells, which lack endogenous EGF receptors, were transformed as efficiently as NIH3T3 cells by the hEGFR virus. The dose-dependent growth response to EGF of infected NR6 cells grown in serum-free medium can be used as a highly sensitive bioassay for the quantitative assessment of EGF and transforming growth factor type α (TGFα). This bioassay is at least as sensitive as previously reported radioimmunoassays and can measure a much wider concentration range (10 pg-100 ng/ml). Uninfected NR6 cells or NR6 cells infected by helper virus alone can be used as controls for the EGF specificity of growth stimulation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 0730-2312
    Keywords: insulin receptor ; tyrosine kinase ; pp60src ; phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Both the insulin receptor and the gene product of the Rous sarcoma virus, pp60src, are protein kinases which phosphorylate themselves and other proteins on tyrosinc residues. Addition of the solubilized insulin receptor to purified pp60src increased the phosphorylation of the β-subunit of the insulin receptor. Phosphorylation of the insulin receptor by pp60src occurred both in the absence and presence of insulin but did not alter the insulin dose response for autophosphorylation of the receptor. Increasing concentrations of pp60src increased the phosphorylation of the receptor and at high concentrations equaled the maximal effect produced by insulin. Our observations suggest a possible mechanism by which the metabolically regulated insulin receptor tyrosine kinase could be altered by other tyrosine kinases such as that associated with pp60src. Further studies will be required to determine if the insulin receptor is phosphorylated by pp60src in Rous sarcoma virus-infected cells.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 91 (1977), S. 289-296 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The total membrane fraction of a chick embryo fibroblast (CEF) homogenate accumulates calcium in an energy-dependent manner. This activity can be dissociated into azide-sensitive and azide-insensitive components. The azide-sensitive component of calcium uptake is believed to represent mitochondrial calcium uptake. The azide-insensitive component of calcium uptake is enhanced by the presence of a calcium trapping agent such as oxalate, and cannot utilize, ADP, inorganic phosphate and a Krebs cycle substrate to support uptake. The distribution of the azide-insensitive calcium uptake in subcellular fractions suggests that this uptake occurs in other than mitochondrial membranes. The membranes most likely to contribute to the azide-insensitive component of calcium uptake are the endoplasmic reticulum and plasma membrane. A microsomal preparation from CEF cells is essentially devoid of the azide-sensitive calcium uptake activity. This microsomal activity is similar in characteristics to the sarcoplasmic reticulum of skeletal muscle. However the specific activity of CEF microsomal calcium uptake system is much less than that found in the skeletal muscle system. The transport of calcium by these membranes provide a mechanism for the regulation of cytosol calcium levels and may play a role in the control of movement and growth of cultured cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Verapamil, a clinically important calcium channel blocker, has been found to cause a 40-fold enhancement of killing of the human KB cell line by a cytotoxic conjugate of epidermal growth factor with Pseudomonas exotoxin (EGF-PE). Synergistic effects of verapamil and EGF-PE are also seen on HeLa D98 cells and a human epidermal carcinoma cell line, A431. Verapamil also potentiates the effect of a toxic conjugate formed between Pseudomonas exotoxin and a monoclonal antibody to the human transferrin receptor (anti-TFR-PE) and enhances the effect of Pseudomonas exotoxin (PE) alone. Two other calcium antagonists were tested. Diltiazem enhances the cytotoxic effect of EGF-PE, but nifedipine does not. Verapamil does not affect the binding and uptake of 125I-EGF by KB cells, but it significantly delays the disappearance of internalized 125I-EGF from the cells. Density gradient fractionation studies using cell homogenates suggest that 125I-EGF accumulates in an undegraded form in lysosomes when cells are treated with verapamil. By immunofluorescence microscopy using an antibody to PE, EGF-PE was found to accumulate in lysosomes; by electron microscopy the lysosomes had an abnormal appearance. The effects of verapamil on toxicity of EGF-PE and lysosomal function appear to be related. However, it is not known whether the enhanced toxicity of EGF-PE in the presence of verapamil is due to its delayed degradation in lysosomes or some more general effect of verapamil on membrane permeability.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mutants of the human KB carcinoma cell line resistant to a cytotoxic conjugate of epidermal growth factor and Pseudomonas exotoxin (EGF-PE) express a pleiotropic phenotype, which includes reduced levels of 125I-EGF binding, without altered affinity for EGF (Lyall et al., 1987). Here, the EGF-toxin (ET) resistant mutants were further characterized with respect to the amount and size of the EGF receptor and the level of EGF receptor RNA. These data indicate that decreased binding of 125I-EGF in the mutants is due to reduced amounts of EGF receptor, which is associated with decreased mRNA levels. Changes in other proteins in the ET mutants were also examined. Five of the six ET mutants had a decrease in a 78,000 Mr- membrane glycoprotein. In addition, an increase in a protein with a Mr- of 40,000 and a pl = 8.0 was found in all the mutants, and an increase in a series of proteins with a Mr- of 36,000 and a pl of 6.3-6.5 was found in some of the mutants. These results confirm the pleiotropic nature of the EGF-PE resistant mutants and show that reduced EGF binding is due to altered expression of the EGF receptor gene in the mutants.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 101 (1979), S. 101-108 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When calcium is removed from culture medium, motility of cultured cells is decreased. The effect is rapid, reversible and pronounced. Decreased motility is observed with normal mouse Balb/c 3T3 cells, mouse L929 cells, rat kidney fibroblasts and chick embryo fibroblasts. The calcium dependence of movement can be observed both with individual cells and with the movement of the margin of a monolayer into a wound. Magnesium will not substitute for calcium to maintain motility. Strontium will substitute, but is not as effective as calcium for maintaining cell movement. Low concentrations of the divalent cation ionophore A23187 (0.5-1 μm) partially reverse the reduced migration observed at low calcium concentrations. These results are consistent with the hypothesis that movement of non-muscle cells occurs through mechanisms similar to those important in the contraction of muscle.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Membranes isolated from subconfluent cultures of Balb/c 3T3 cells have low energy-dependent calcium uptake activity. Replating confluent cells at low density results in a prompt fall of energy-dependent calcium uptake by membrane fractions. The level to which uptake activity falls is a function of the density at which the cells are plated (Moore and Pastan, '77b). To determine if regulation of energy-dependent uptake of calcium by membrane fractions is dependent upon attachment to a substrate and to further characterize conditions that regulate the process, we examined calcium uptake activity of membranes isolated from cells in suspension. With cells in suspension energy-dependent calcium uptake activity of isolated membranes falls promptly if cells are diluted to a low density (〈105 cells/ml) and is a function of cell density. When cells in suspension at low cell densities are concentrated to high cell densities (〉2 X 106 cells/ml), calcium uptake activity of the isolated membrane fraction is increased as a function of cell density. These changes of membrane calcium uptake activity occur promptly and do not require protein synthesis.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...