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  • Electronic Resource  (17)
  • Biochemistry and Biotechnology  (12)
  • glycosylation  (5)
  • Atomic, Molecular and Optical Physics  (3)
  • 1
    ISSN: 1573-7217
    Keywords: breast cancer ; glycosylation ; HPA ; Helix pomatia lectin ; prognosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Abnormal cellular glycosylation as demonstrated by the binding of a lectin fromHelix pomatia (HPA) to paraffin-embedded sections has been shown in several studies to be associated with aggressive biological behaviour and poor long-term patient prognosis in breast cancer. This study aims to address the possibility that expression of the HPA binding ligand may be of prognostic significance through an association with increased cellular proliferation (as measured by S-phase fraction and histological grade), anaplasia (reflected in histological grade), or ploidy (DNA index). In a 24 year retrospective study, paraffin-embedded sections of 366 primary breast cancers were stained for binding of HPA. All tumours were assessed for histological grade. Flow cytometry was performed on all cases for which sufficient tumour tissue was available (358/366 cases) and S-phase fraction (SPF) and ploidy calculated. Data regarding patient age at diagnosis, nodal status, and tumour size were also recorded. Life table analyses revealed survival advantage for HPA ‘non stainers’ in comparison to ‘stainers’ (p〈 0.001); for patients with tumours of low grade vs. high grade (p〈0.001); and for those with tumours of low SPF vs. high SPF (p〈0.001). No survival advantage was shown for those with diploid vs. aneuploid tumours (p= 0.17). No association was apparent between HPA binding and grade, SPF, or ploidy (Chi squared values not significant). This was confirmed by multivariate analysis in which nodal status, tumour size, and SPF were independently predictive of survival. There was no confounding effect of grade, SPF, or ploidy upon the correlation between survival and HPA binding. HPA was, however, not independently predictive owing to its strong association with nodal status. The results of this study suggest that the prognostic significance of altered glycosylation, as detected by HPA binding, is unlikely to be through an association with proliferative rate, degree of anaplasia, or cellular ploidy, but may rather be through a direct association with the presence of nodal metastases.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7276
    Keywords: colon cancer ; glycosylation ; Helix pomatia agglutinin ; metastasis ; SCID mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Human colonic cancer cells (HT-29, 10 7 cells/dose) were injected subcutaneously between the scapulae of 19 severe combined immunodeficient (SCID) mice. After 19 days, large tumours had developed in 18 out of the 19 animals and the mice were then killed. Metastases were detected in the lungs of 16 animals but not in other organs investigated. Surgical removal of the primary tumour in another group of five animals led to a prolonged survival and further growth of metastases in the lungs. HT-29 injection into the tail vein (n=5)resulted in colonization of the lungs. The tumours that developed in the animals were signet cell carcinomas; these forms are not seen in HT-29 cells in culture. Glycoconjugate expression of the tumours was assessed using several lectins. In many cases the results indicated a stability of lectin-binding patterns from cell culture conditions to implantation into the SCID mice. This was true for the lectin Helix pomatia agglutinin (HPA), the binding of which is associated with a high metastatic potential in some human tumours, including colon cancer. All the primary tumours and metastases were HPA positive. This xenograft tumour model seems to be a clinically relevant system for the study of glycoconjugate expression in human colon cancer cells and their metastases.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 6 (1972), S. 787-791 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution of the time dependent Schrödinger equation, including renormalization of the wave function, is used to obtain quantum mechanical expressions for the optical rotation and the circular dichroism. The use and form of the radiative damping term is examined with respect to its effects in the circular dichroism formula.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 34 (1988), S. 85-98 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The edge inversion process in phosphoric acid, PO(OH)3 has been studied by large scale ab initio molecular orbital theory. Edge inversion of the tetrahedral ground state via a square-planar transition state requires 69.5 kcal/mol (MP-2). Addition of two NH3 solvent molecules to the vacant NLUMO stabilizes the transition state by 45 kcal/mol (MP-2). The value for ΔH(300K) for the reaction 2NH3 + PO(OH)3 → PO(OH)3 · (NH3)2 is 24.1 kcal/mol (MP-2). The complex with two NH3 molecules is an intermediate. Addition of one NH3 to PO(OH)3 leads to an energy lowering of the planar form of 31 kcal/mol. This structure is now a transition state. The value for ΔH(300K) for the reaction NH3 + PO(OH)3 → PO(OH)3 · NH3 is 38.6 kcal/mol (MP-2). The complex of PF3O with two NH3 molecules was studied and is an intermediate. The value for ΔH(300K) for the reaction 2NH3 + POF3 → POF3 · (NH3)2 is only 3.3 kcal/mol (MP-2). Electron-donor solvents clearly will stabilize the edge inversion transition state for tetracoordinate main group compounds.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 269-279 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular and electronic structures of ADPO 1, a model thiapentalene 2, and [Xe2F3]+ have been calculated in the local-density functional (LDF) formalism with polarized double numerical basis sets. The molecules were calculated to have planar C2ν structures in agreement with experiment and in contrast to Hartree-Fock molecular-orbital calculations. The vibrational spectra of all species were calculated to show that the optimized structures are indeed minima. The calculated spectrum of [Xe2F3]+ is compared with the experimental one and excellent agreement is found. These results demonstrate that the LDF method can be applied to the prediction of molecular structures containing hypervalent bonds.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 769-784 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The morphology of yeast cells as it is affected by the glycosidic linkages of constituent glucan was studied. Four different strains of Saccharomyces cerevisiae were studied. A cell wall matrix particle representing the intact original morphology and composed entirely of β-glucan was prepared. Using prepared cell wall glucan particles, the morphology and cell wall matrix structure were examined. Genetic modification of the cell wall structure during growth results in the alteration of the shape and hydrodnamic volume of the intact cell wall particles. The shape and hydrodynamic volume of the cell wall particles can also be modified by in vitro chemical and enzymatic treatment. The shape factor and hydrodynamic volume of the whole glucan cell wall matrix particles were evaluated quantitatively using a rheological analysis. An increased degree of β(1 → 6) cross-linking in the cell wall matrix induces a nearly 2-fold increase in the shape factor and a 10-fold increase in the compression modulus of the glucan particles. The disruption of β(1 → 6) glycosidic cross-linking causes the particles to swell by up to 18% of their original volume. This was used as a strategy to isolate a yeast mutant with a high β(1 → 6) glycosidic content in the cell wall glucan.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0006-3592
    Keywords: chemostat ; glucose limitation ; glycosylation ; CHO cells ; interferon-γ ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The physiology of a recombinant Chinese hamster ovary cell line in glucose-limited chemostat culture was studied over a range of dilution rates (D = 0.008 to 0.20 h-1). The specific growth rate (μ) deviated from D at low dilution rates due to an increased specific death rate. Extrapolation of these data suggested a minimum specific growth rate of 0.011 h-1 (μmax = 0.025 h-1) The metabolism at each steady state was characterized by determining the metabolic quotients for glucose, lactate, ammonia, amino acids, and interferon-γ (IFN-γ). The specific rate of glucose uptake increased linearly with μ, and the saturation constant for glucose (Ks) was calculated to be 59.6 μM. There was a linear increase in the rate of lactate production with a higher yield of lactate from glucose at high growth rates. The decline in the rate of production of lactate, alanine, and serine at low growth rate was consistent with the limitation of the glycolytic pathway by glucose. The specific rate of IFN-γ production increased with μ in a manner indicative of a growth-related product. Despite changes in the IFN-γ production rate and cell physiology, the pattern of IFN-γ glycosylation was similar at all except the lowest growth rates where there was increased production of nonglycosylated IFN-γ. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0006-3592
    Keywords: Chinese hamster ovary ; interferon-γ ; chemostat culture ; glycosylation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Chinese hamster ovary (CHO) cell line expressing recombinant human interferon-γ (IFN-γ) was grown under glucose limitation in a chemostate at a constant dilution rate of 0.015 h-1 with glucose feed concentrations of 2.75 mM and 4.25 mM. The changes in cell concentration that accompanied changes in the glucose feed concentration indicated that the cells were glucose-limited. The cell yield on glucose remained constant, but there was a decline in residual glucose concentration and a reduced lactate yield from glucose in the latter stages of the culture. The consumption rates for many of the essential amino acids were increased later in the culture. The volumetric rate of interferon-γ production was maintained throughout the course of this culture, indicating that IFN-γ expression was stable under these conditions. However, the specific rate of IFN-γ production was significantly lower at the higher glucose feed concentration. Under glucose limitation, the proportion of fully glycosylated IFN-γ produced by these cells was less than that produced in the early stages of batch cultures. The proportion of fully glycosylated IFN-γ increased during transient periods of glucose excess, suggesting that the culture environment influences the glycosylation of IFN-γ.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 147-158 
    ISSN: 0006-3592
    Keywords: CHO cell ; cell aggregation ; recombinant human interferon-γ ; mammalian cell culture ; cell culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Chinese hamster ovary (CHO) cell line has great commercial importance in the production of recombinant human proteins, especially those for therapeutic use. Much attention has been paid to CHO cell population physiology in order to define factors affecting product fidelity and yield. Such studies have revealed that recombinant proteins, including human interferon-γ (IFN-γ), can be heterogeneous both in glycosylation and in proteolytic processing. The type of heterogeneity observed depends on the growth physiology of the cell population, although the relationship between them is complex. In this article we report results of a cytological study of the CHO320 line which expresses recombinant human IFN-γ. When grown in suspension culture, this cell line exhibited three types of heterogeneity: (1) heterogeneity of the production of IFN-γ within the cell population, (2) heterogeneity of the number of nuclei and mitotic spindles in dividing cells, and (3) heterogeneity of cellular environment. The last of these arises from cell aggregates which form in suspension culture: Some cells are exposed to the culture medium; others are fully enclosed within the mass with little or no direct access to the medium. Thus, live cells producing IFN-γ are heterogeneous in their environment, with variable access to O2 and nutrients. Within the aggregates, it appears that live cells proliferate on a dead cell mass. The layer of live cells can be several cells deep. Specific cell-cell attachments are observed between the living cells in these aggregates. Two proteins, known to be required for the formation of certain types of intercellular junctions, spectrin and vinculin, have been localized to the regions of cell-cell contact. The aggregation of the cells appears to be an active process requiring protein synthesis. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 10
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Experiments were performed on a cellulose acetate ultrafiltration membrane (HF-200, ABCOR Inc., Cambridge, Mass.) to test its efficacy in concentrating and purifying a crude enzyme (trypsin) preparation. Studies were also made to determine the influence of inorganic salts, pressure, and temperature on the rate of ultrafiltration for this membrane. The results showed reductions in the rates will be encountered due to the presence of inorganic salts. However, the reduced rates were still sufficiently high to make this method extremely attractive. Operating at filtration pressures above 75 psi at, 20 to 30°C for this membrane does not show any beneficial effect in terms of ultrafiltration rates. However, at 10°C there were continual increases in the filtration rates up to 100 psi. Concentration and purification studies with trypsin yielded a concentration factor of 8.35 and a purification factor 2.35. It was shown concretely that the purification of the enzyme was due to the passage of low molecular weight proteins (below 20,000) through the membrane. Enzyme activity slightly greater than 90% was obtained: 70% was found in the concentrate and 20% in the filtrate. It is concluded that membrane ultrafiltration is an ideal simple, rapid, and economical method for the recovery of biological active substances.
    Additional Material: 7 Ill.
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