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  • 1995-1999  (7)
  • Biochemistry and Biotechnology  (5)
  • Colon  (2)
  • Evolution
  • glycosylation
  • 1
    Electronic Resource
    Electronic Resource
    Laparoscopic-assisted colectomy learning curve (1995)
    Springer
    Diseases of the colon & rectum 38 (1995), S. 600-603 
    Details
    ISSN: 1530-0358
    Keywords: Colon ; Laparoscopy ; Resection ; Surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: The purpose of this paper is to establish the number of cases necessary to master laparoscopic removal of the left or right colon. METHODS: Data were obtained by chart review and by individually completed questionnaires. RESULTS: A total of 144 laparoscopic-assisted or intracorporeal right or left hemicolectomies were completed by four surgeons at separate institutions. Questionnaires were completed by each surgeon for each sequential hemicolectomy, and data concerning the type of surgery and total operating time were recorded. Times were plotted to diagram individual learning curves for each surgeon, and data grouping methods were used to determine the curve for each surgeon as well as for the combined data base. Learning was said to have been completed when the surgeon's operative time reached a low point and subsequently did not vary by more than 30 minutes. A total of 78 right colectomies and 66 left colectomies were completed by the group. Respectively, each surgeon appeared to learn the procedure after 16, 21, 11, and 6 cases. When the entire database was analyzed as a whole, it was shown that between 11 and 15 completed colectomies were needed for learning, after which operative times remained relatively stable. CONCLUSIONS: This analysis, using total operative time as an indication of learning, shows that approximately 11 to 15 completed laparoscopic colectomies are needed to comfortably learn this procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02054118
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  • 2
    Electronic Resource
    Electronic Resource
    Basal and meal-stimulated colonic absorption (1996)
    Springer
    Diseases of the colon & rectum 39 (1996), S. 865-870 
    Details
    ISSN: 1530-0358
    Keywords: Colon ; Absorption ; Water ; Sodium ; Chloride ; Thiry-Vella Fistula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: Few quantitative experiments evaluating colonic absorption of water and electrolytes have been performed using an awake, conscious animal model. The purpose of these experiments was to develop this type of model and evaluate both basal and meal-stimulated colonic absorption of water and electrolytes. METHODS: Canine Thiry-Vella fistulas were created using a 20 cm segment of distal colon under general anesthesia. Colonic absorption studies were performed using infusion of the Thiry-Vella fistulas with a buffer solution containing [14C]polyethylene glycol. Electrolyte analysis and concentration of radioactivity in the effluent were obtained and used to calculate the net flux of water, sodium, and chloride. Each study consisted of an one-hour basal period and a three-hour experimental period divided into two groups. Group 1 received no meal. Group 2 orally ingested a mixed meal at the completion of the basal hour. RESULTS: In the basal state, water and electrolytes are absorbed from the distal colon at a steady and constant rate. An orally ingested meal produces a statistically significant increase in the rate of absorption, independent of direct colonic luminal contact with the nutrients of the meal given. CONCLUSIONS: These studies demonstrate an in vivo quantitative and qualitative measure of mammalian colonic water and electrolyte absorption. An increase in absorption rate occurs in response to a meal that is probably the result of an unidentified neural or humoral signal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02053984
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Heterogeneity within populations of recombinant Chinese hamster ovary cells expressing human interferon-γ (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 147-158 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260460208
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  • 4
    Electronic Resource
    Electronic Resource
    N-glycans of recombinant human interferon-γ change during batch culture of chinese hamster ovary cells (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 639-648 
    Details
    ISSN: 0006-3592
    Keywords: interferon ; glycosylation ; CHO cells ; microheterogeneity ; mass spectrometry ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A recombinant Chinese hamster ovary (CHO) cell line making human interfron-γ (IFN-γ) was grown in 12-L stirred tank fermentors in three batch fermentations under conditions of constant temperature, pH, and dissolved oxygen tension. In addition to cell growth, metabolite, and productivity data, a detailed analysis of the carbohydrate structures attached to each glycosylation site of IFN-γ was achieved using matrix-assisted laser desorption mass spectrometry (MALDI-MS) in combination with exoglycosidase array sequencing. Complex biantennary oligosaccharides (particularly Gal2GlcNAc4Man3 which was core ℵl-6 fucosylated at Asn25 but not at Asng97) were most prevalent at both glycosylation sites. However, considerable microheterogeneity arising from the presence of triantennary and truncated glycan structures was also observed. The proportion of the dominant core glycan structure (Gal2GlcNAc4Man3 ± Fuc1) decreased by 15-26% during batch culture, with increases in the proportion of oligomannose and truncated glycans over the same time period. Prolonged culture resulting from an extended lag phase led to further accumulation of oligomannose and truncated structures, reaching up to 52% of total glycans attached to Asng97 by 240 h of culture. The implications of these glycosylation changes for optimizing the time for harvesting cell cultures, and for the clearance of recombinant therapeutic products in vivo are discussed. © 1995 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480612
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  • 5
    Electronic Resource
    Electronic Resource
    Extension of Sp2/0 hybridoma cell viability through interleukin-6 supplementation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 439-446 
    Details
    ISSN: 0006-3592
    Keywords: cell culture viability ; apoptosis ; IL-6 ; hybridomas ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sp2/0 hybridoma cells die principally by apoptosis in batch culture. We have found that cultures of the Sp2/0 hybridoma exhibit increased viability in response to interleukin 6 (IL-6) supplementation relative to control cultures during serum shiftdown experiments. When shifted from a medium containing 10% fetal bovine serum (FBS) to a medium with 1% FBS, IL-6 supplemented cultures displayed viabilities and viable cell densities similar to control cultures containing 10% FBS. The degree of the survival response induced varied in accordance with the severity of the shiftdown, as cells resuspended in a high serum medium showed little observable enhancement in viability. The extension in culture viability was not accompanied by an observable decrease in growth relative to control cultures, indicating that the effect was not a consequence of growth inhibition. These results suggest the existence of serum components with behavior functionally similar to IL-6, with respect to enhancing cell survival, and that under certain experimental conditions IL-6 serves as a survival factor. In contrast to the extended viability displayed by cultures supplemented with IL-6, Sp2/0 cultures transfected with IL-6 cDNA expression vectors displayed a growth inhibitory response relative to control cultures. This inhibitory response was characterized by an extended lag phase following inoculation, and a decrease in batch culture cell yield. The depression in cell yield varied with serum concentration, with the largest depression occurring at high serum concentrations. We conclude that interactions between components in serum, presumably growth factors, and cytokines play an important role in altering the behavior of industrially relevant cell lines in culture. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 439-446, 1997.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Polyvinyl alcohol-coated perfluorocarbon supports for metal chelating affinity separation of a monoclonal antibody (1996)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 9 (1996), S. 394-400 
    Details
    ISSN: 0952-3499
    Keywords: perfluorocarbon affinity support ; metal chelate ; immobilized metal affinity ; IMAC ; monoclonal antibody ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The preparation, characterisation and testing of stable non-porous coated perfluorocarbon supports functionalised with the metal chelate, iminodiacetic acid (IDA) is described. Polyvinyl alcohol (PVA), a neutral hydrophilic polymer was esterified with perfluorooctanoyl chloride and anchored to the surface of solid perfluorocarbon particles through multiple fluorophilic interactions. The PVA-coated particles were then activated by epoxidation and coupled with IDA. The presence of surface-attached chelates was clearly demonstrated by the binding and selective desorption of Zn2+ ions. Three particulate perfluorocarbons were selected as potential starting materials and the conditions for preparation of metal chelating adsorbents optimised with respect to ease of manufacture, ligand density and binding capacity towards a monoclonal antibody known to bind to commercial Zn2+-IDA supports. The choice of base particle strongly influenced the ligand densities and specific binding capacities towards the monoclonal antibody that could be achieved under optimal preparative conditions. Possible ways in which these metal chelating adsorbents may be employed to recover the monoclonal antibody directly from culture vessels are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    Growth factor and Bcl-2 mediated survival during abortive proliferation of hybridoma cell line (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 164-171 
    Details
    ISSN: 0006-3592
    Keywords: cell death ; apoptosis ; bcl -2 ; cell culture ; cell viability ; growth factors ; survival factors ; abortive proliferation ; hybridomas ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Cultures of the CRL-1606 hybridoma (ATCC) have been reported to undergo continuous proliferation with simultaneous death during nutrient limited fed-batch fermentations. The bcl-2 proto-oncogene has been shown to prevent cell death under a variety of otherwise death inducing conditions. We were interested in elucidating the nature of the massive death observed in cultures of CRL-1606, specifically with respect to the possible environmental causes, and the ability of overexpressed human bcl-2 (hbcl-2) to mitigate cell death. Abortive proliferation, or continuous proliferation in the presence of continuous death, could be induced in serum free cultures of CRL-1606 through the withdrawal of insulin provided the culture was competent for cell proliferation. Culture competency for proliferation was found to be solely determined by the presence of cell culture nutrients. Abortive proliferation was defective in cultures transfected with hbcl-2 and the enhanced viability observed resulted from an increased viable cell population and at the expense of the nonviable cell population normally found in untransfected cultures. Abortive proliferation was also observed in serum containing cultures upon serum shiftdowns. Like the insulin-supplemented serum free culture system, hbcl-2 transfected cultures exhibited defects in the abortive proliferation process. These results suggest that the massive death observed during nutrient-limited fed-batch fermentation originate, in part, from growth or survival factor limitations. Hence, approaches to design cell culture media that account for the cell's proliferation requirements without accounting for the cell's survival requirements may represent a cell death sentence. Given the transformed nature of the hybridomas, we conclude that the abortive proliferation of CRL-1606 is a consequence of inappropriate cell cycle entry in a survival factor limited environment. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 164-171, 1998.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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