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  • 1
    Electronic Resource
    Electronic Resource
    Zygotic expression of the connexin43 gene supplies subunits for gap junction assembly during mouse preimplantation development (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 18-26 
    Details
    ISSN: 1040-452X
    Keywords: Gap junction protein ; Gene expression ; Compaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: De novo assembly of gap junctions begins during compaction in the eight-cell stage of mouse development, and intercellular coupling mediated by gap junctions appears to be required for maintenance of the compacted state. We have begun to explore the expression of the family of genes encoding the connexins, the proteins that form the gap junction channels. We recently reported that a protein with antigenic and size similarity with connexin32, the rat liver gap junction protein, is inherited as an oogenetic product by the mouse zygote, but its gene appears not to be transcribed prior to implantation (Barron et al., Dev Genet 10:318-323, 1989). Here we report that another member of this gene family, connexin43, is transcribed by the embryonic genome from shortly after the time of genomic activation. As revealed by Northern blotting, connexin43 mRNA is absent from ovulated oocytes, becomes detectable in the 4-cell stage, and accumulates steadily thereafter to reach a maximum in blastocysts. In contrast, no transcripts of connexin26 could be detected in any preimplantation stage. A protein with antigenic and size similarity with connexin43 from rat heart was found by Western blotting to accumulate from the four-cell stage onward. Immunofluorescence analysis with embryo whole mounts was used to demonstrate that this protein is incorporated into punctate interblastomeric foci during compaction, consistent with its assembly into gap junction plaques. We conclude that connexin43 is one member of the connexin gene family whose zygotic expression is critical for preimplantation morphogenesis.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080300103
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  • 2
    Electronic Resource
    Electronic Resource
    A monoclonal antibody to the human epidermal growth factor receptor (1982)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 20 (1982), S. 149-161 
    Details
    ISSN: 0730-2312
    Keywords: monoclonal antibody ; A431 ; EGF receptor ; chromosomal location ; internalization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A monoclonal antibody of the IgG class, EGFR1, has been isolated using cells of the epidermoid carcinoma line A431 as immunogen. The A431 antigen recognized by EGFR1 has an apparent molecular weight of approximately 175,000, is a cell-surface molecule which can be specifically cross-linked to EGF, exhibits an EGF-stimulated protein kinase activity, binds to EGFR1 in a number of human cell lines to a degree which parallels EGF binding, and shows EGF-dependent internalization in A431 cells and human fibroblasts. We therefore conclude that EGFR1 is directed against an antigenic site on the human EGF receptor. EGFR1 is not mitogenic for human fibroblasts and does not inhibit EGF binding under a variety of assay conditions. The characterization of EGFR1 has allowed the unambiguous assignment of the structural gene for the human EGF receptor to chromosome 7. Preliminary results suggest that a convenient method for isolating a range of anti-EGF receptor monoclonal antibodies can be developed, based on a hybridoma supernatant screening assay in which positive supernatants bind selectively to a human-mouse cell hybrid containing human chromosome 7.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240200207
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  • 3
    Electronic Resource
    Electronic Resource
    Factors affecting the production of glutamine in cultured mouse cells (1971)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 77 (1971), S. 135-144 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Glutamine synthetase activity of NCTC clone 929 mouse cells (strain L) was studied as a function of the prior nutritional experience of the cells. Small enzyme increases were recorded in response to either glutamine depletion or chronic serum supplementation of the growth medium. Somewhat greater increases resulted from the administration of cortisol or certain other steroids, particularly if the hormone treatment was combined with glutamine withdrawal. High concentrations of glutamate in the medium did not augment the glutamine synthetase content of the cells and even caused an apparent decrease in it. The presence of glutamine in the culture medium resulted in a fairly rapid rate of disappearance of the glutamine synthetase of previously induced cells. The data suggest that glutamine and cortisol act independently on the cells in regulating the level of the enzyme.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1040770203
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  • 4
    Electronic Resource
    Electronic Resource
    Regulation of production of a platelet-derived growth factor-like protein by cultured bovine aortic endothelial cells (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 121 (1984), S. 298-308 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Platelet-derived growth factor (PDGF) is a potent mitogen for cultured cells of mesenchymal origin. Known sources of PDGF or PDGF-like protein are blood platelets, several transformed cell lines, and cultured endothelial cells (EC). We have examined the regulation of production of a PDGF-like protein in cultures of bovine aortic EC using a specific radioreceptor assay for PDGF. EC constitutively secreted PDGF-like protein into serum-containing or serum-free medium. The rate of production of PDGF-like protein was constant for at least 3 weeks and was not due to release of an internal store, since cell lysis by repeated freeze/thaw cycles did not relase significant amounts of the protein. Synthesis of PDGF-like protein was sensitive to changes in the pH of the media and was maximal at pH 8.5. Production of PDGF-like protein was independent of EC growth rate: rapidly dividing cells and confluent, quiescent cells produced equal amounts per cell. However, sparse, quiescent EC produced more PDGF-like protein per cell than did confluent, quiescent cells. Several phorbol esters stimulated production of PDGF-like protein. At a concentration of 10-6 M, a twofold stimulation was observed upon addition of the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA) and nearly a fourfold stimulation upon addition of the nonpromoting analog, methyl TPA. Incubation of EC with endotoxin (10 μ/ml) resulted in a twofold stimulation of PDGF-like protein production. In all experiments with endotoxin and phorbol esters, an increase in the production of PDGF-like protein was accompanied by morphological changes in the EC cultures. The cells appeared elongated and fibroblastic and exhibited low viability. A mathematical model was developed in which PDGF-like protein production was shown to consist of two separate components - production at a constant rate by healthy cells and a large burst of synthesis and secretion by dying cells. These results suggest that injurious agents may be capable of stimulating production of a growth factor by the endothelium.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041210206
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  • 5
    Electronic Resource
    Electronic Resource
    Approximation of continuous growth of Cephalotaxus harringtonia plant cell cultures using fed-batch operation (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 241-246 
    Details
    ISSN: 0006-3592
    Keywords: fed-batch operation ; continuous approximation ; growth kinetics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In Cephalotaxus harringtonia plant cell cultures, periods of batch growth that are limited by hexose uptake are too short to make an accurate estimate of the Monod saturation constant. Continuous cultures are infeasible on a laboratory scale, and semicontinuous cultures require too frequent sampling. Fed-batch operation, consisting of intermittent removal from a culture that is fed continuously, was investigated as a possible solution to these problems. For a constant feed rate, computer simulations showed that a steady state can be achieved which is useful for studying growth at different specific growth rates. In terms of the dilution rate it was confirmed that the operation is essentially equivalent to continuous culture when the samples represent a small fraction of the total culture volume. Experiments with glucose or fructose as the carbon source were carried out in shake flasks fed by a multichannel syringe pump. Results indicate that Monod kinetics based on medium glucose levels cannot adequately describe growth under these conditions. Monod's expression for specific growth rate using internal glucose concentration gives an improved correlation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380305
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of a postlavage, in situ pulmonary macrophage population (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 111 (1982), S. 97-103 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A postlavage in situ subpopulation of pulmonary macrophages (PM), biochemically distinct from the lavaged population, has recently been isolated from rats. After exhaustive bronchopulmonary lavage to extract the free lung cells, the lungs were excised, homogenized, and filtered, and the resultant cell suspension was allowed to form a monolayer on plastic Petri dishes. Electron microscopic morphometry failed to indicate any morphologic differences in the two populations. The postlavage in situ PM were more active metabolically during phagocytosis of zymosan particles or stimulation by phorbol myristate acetate (PMA) than the corresponding lavage population, as evidenced by greater superoxide generation. Macrophages prepared by either method became more avidly phagocytic when incubated with cell-free medium isolated in the preparation of the in situ population. Peroxidase, an enzyme absent from the granules of PM separated by lavage techniques, was found in a granule-rich fraction of the in situ macrophage. Catalase activity was found in similar amounts in both supernatants and granule-rich fractions of both populations. The results support the concept of subpopulations of PM and suggest that these subpopulations are distinguished by their biochemical properties and their functional abilities.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041110115
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  • 7
    Electronic Resource
    Electronic Resource
    An improved, totally automated antibiotic bioassay machine (1969)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 11 (1969), S. 1011-1025 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A number of improvements have been made in a totally-automated antibiotic bioassay machine previously described. The new machine accepts unmeasured, untreated, opaque suspensions of fermentation beers three times faster (120 samples per hour) and supplies printed potencies sooner (in just over two hours). Whereas the original machine employed a self-cleaning filter and used disposable two milliliter beakers, this version involves a batch-dialysis scheme for effecting sample purification, and provides for automated cleaning of incubation chambers.In operation, a measured, portion of thoroughly-mixed fermentation beer is automatically diluted and transferred into one side of an incubation chamber, the two halves of which are separated by a dialysis membrane. The other half is filled with inoculated media. During the two hour incubation at 37°, dialyzable antibiotic limits growth of the inoculum in proportion to its concentration. After incubation, the turbidity of the inoculum is simultaneously read by an online computer and plotted on a strip chart recorded. The computer suplies printed potency values and sample identification on site, while the recording provides the operator with an analog record of turbidity. Fiber optics are employed in the turbidmetric readout, and an electric typewrite provides the printout.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260110522
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  • 8
    Electronic Resource
    Electronic Resource
    Biopolymers in drug technology: The use of DNA in purifying Phleomycin (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 15 (1973), S. 1039-1044 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: It is sometimes easier and cheaper to extract a drug's target sites from cells than it is to purify, concentrate or manufacture the drug itself. This is especially true in the case of DNA and some of the exotic antibiotics that react with it. Phleomycin, an inhibitor of replication, was considered as a specific case in point. Biologically active components of this antibiotic mixture bind nondestructively to DNA, in vitro and in vivo, and thereafter may be processed by simple, economical methods usually reserved to macromolecules of much greater size.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260150604
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  • 9
    Electronic Resource
    Electronic Resource
    Deactivation of immobilized beef liver catalase by hydrogen peroxide (1974)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 16 (1974), S. 1659-1673 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Immobilized beef liver catalase has been used in a flow reactor to decompose hydrogen peroxide; at the same time the catalase is inactivated by its substrate. A model has been developed which predicts this rate of decomposition of peroxide and inactivation of catalase. First order dependence on peroxide concentration is assumed. The model was verified by experiment for a range of operating conditions and then used to predict the effects of a change in operating variables.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260161208
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  • 10
    Electronic Resource
    Electronic Resource
    Enzyme-coupled ultrafiltration membranes (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 17 (1975), S. 445-449 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260170313
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