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  • 1
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: This study reports some findings on the effects of centrifugation on the viability of mammalian cells. The authors used Burkitt lymphoma cells cultivated in a synthetic medium containing 10% fetal calf serum for all experiments. Batch centrifugations were conducted in a RC2-B centrifuge (Ivan Sorvall, Incorporated, Norwalk, Connecticut USA) operated at 0 and 25°C. During centrifugation we exposed the cells to gravitational fields ranging from 24,800 to 42.200g. The results showed that at, 0°C and 25,800 or 42,000g no loss in cell viability occurred for up to 90 min exposures in the centrifugal field. However, at 25°C and for gravitational fields of 24,800 and 42,000g, there were appreciable losses in cell viability. Continuous centrifugation studies in the Sharples supercentrifuge (Division of Penn Salt Corporation, Warminister, Pennsylvania USA) were also conducted with bowl speeds up to 28,000 rpm (19,000g) and flow rates ranging from 1.4 to 20 1, hr. Slight, losses in cell viability were noted and postulated as caused by the shear stresses encountered by the cells. Some pumping studies using the lymphoma cells substantiate this conclusion.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0006-3592
    Keywords: RGD ; FMDV ; internalization ; integrins ; cell binding ; β-galactosidase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The G-H loop of foot-and-mouth disease virus is a disordered protrusion of the VP1 protein exposed on the virion surface. This short stretch includes an arginine-glycine-aspartic acid tripeptide, a recognized integrin-binding motif, which is responsible for cell attachment and infection. Eight copies of a peptide reproducing the amino acid sequence of this FMDV ligand have been displayed in solvent-exposed regions on an enzymatically active recombinant β-galactosidase. This viral peptide segment enables the chimeric enzyme to bind mammalian cell lines with different efficiencies, probably depending on the number of suitable cell receptors present on each of them. Moreover, it also promotes the internalization of the attached enzyme, which is transiently active inside the cells. These results suggest further exploration of the potential use of short adhesion peptides of viral origin as cell attachment tags to direct the targeted delivery of both genes and enzymes, instead of whole, infectious viruses. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:294-301, 1998.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 237 (1993), S. 400-407 
    ISSN: 0003-276X
    Keywords: Human embryo ; Crown-rump length ; Greatest length ; Computer analysis ; Vaginal ultrasound ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Accurate information on the normal growth rate of the human embryo is fundamental to a better understanding of the embryonic period of pregnancy. Crown-rump length measured previously in utero (N = 227) with vaginal ultrasound in 107 in vitro fertilization (IVF) or gamete intrafallopian transfer (GIFT) singleton pregnancies was compared to the greatest length of fixed human embryos from the Carnegie collection, of known developmental stage whose postovulatory ages were estimated from menstrual histories. Average crown-rump length in utero was 60% of the greatest length of the fixed specimens prior to postovulation day 33, but were equal after postovulation day 40. The growth rate of in utero embryos and fixed specimens, analyzed by computer using exponential equations, was compared to linear and polynomial equations used in previously published embryo growth tables. The exponential equation, length = exp(a + b/age), fit in utero measurements best, while the equation length = exp[a + b/exp(age)] fit the fixed specimens best. Differences between length in utero and in fixed specimens may be related to distortion of the fixed embryos resulting from the formalin fixation, to ultrasound distortion, to curling of the embryo, or to incorrectly estimated ages of the fixed specimens. Study of human embryos in utero is now practical with vaginal ultrasound. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 210 (1984), S. 491-502 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The ultrastructure of the parotid gland was examined in the little brown bat. The seromucous acinar cells contained abundant granules of variable morphology. These granules were characterized by a submembranous dense layer consisting of fine parallel slats. In some bats, the matrix of the granules was structureless, whereas in others it consisted of closely packed but randomly arranged bundles of tubules. The intercalated ducts had a highly developed rough endoplasmic reticulum, often containing large numbers of intracisternal granules. In contrast, only a few secretory granules were present in the supranuclear cytoplasm. The striated ducts, which exhibited the characteristic basal striations consisting of vertically oriented mitochondria and highly folded plasmalemmas, contained numerous small dense granules in a subluminal band. These granules had a paracrystalline substructure with a periodicity of 8 nm. Excretory ducts strongly resembled striated ducts. They showed the same kind of basal striations and about half their constituent cells contained small paracrystalline granules.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A new pH indicator, seminaphthofluorescein (SNAFL)-calcein acetoxymethyl ester, was used for intracellular pH (pHi) measurement in living MDCK cells with a laser scanning confocal microscope (LSCM) equipped with an Argon/Krypton laser and dual-excitation and dual-emission (FITC/Texas Red) filter set. SNAFL-calcein excitation maxima are ∼492/540 nm (acid/base) and emission maxima are ∼535/625 nm (acid/base) with a pKa value at ∼7.0. The absorption/emission spectra of SNAFL-calcein indicate that the ratio of emission intensities of its basic/acidic forms is pH dependent. With an Argon/Krypton LSCM, we were able to monitor the acidic and basic forms of this dye simultaneously using dualexcitation (488/568 nm) and dual-emission (525-614 nm/∼615 nm) wavelengths (λs). The simultaneous dual-excitation/emission LSCM system allows for efficient recording of pHi dynamics (time resolution ≍ 1 sec) in living cells. We have analyzed emission stability of the dye at different temperatures (22°C and 37°C) and constant pH, and at the same temperature (22D°C) but various pHs (6.6, 7.0, and 7.4). Bleaching rate is slightly higher at 37°C than that at 22°C. The basic form of the dye (λEm ≍ 625 nm) has a slightly higher bleaching rate than the acidic form (λEm ≍ 535 nm) in standard culture medium (pH 7.3) at either 22°C or 37°C. The pHi in MDCK cells calculated from ratio images (535 nm/625 nm) was 7.19 ± 0.03 (mean ± SEM, n = 20). Calibration experiments show that the useful pH range of SNAFL-calcein appears to be between 6.2 and 7.8, as the dye is difficult to calibrate outside this pH range. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    BioEssays 11 (1989), S. 124-127 
    ISSN: 0265-9247
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The body plan of the frog is set-up by a rearrangement of the egg cytoplasm shortly after fertilization. Microtubules play several roles in this critical developmental event.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Phenol extracted, alkali-treated lipopolysaccharide (aLPS) from vaccine strain (S19) Brucella abortus was demonstrated by two-dimensional gel electrophoresis to consist of at least ten silver staining, polydisperse analogues having different pIs. When tested on nitrocellulose immunoblots, all ten were antigenically reactive with bovine anti-B. abortus polyclonal sera, but only six reacted with anti-B. abortus O-antigen murine monoclonal antibody. Analogues focusing at different pIs were concluded to arise from differences in either core or O-antigen side chain structure or because of covalently bound protein. While not qualitatively different, aLPS from pathogenic B. abortus strain 2308 had lesser amounts of analogues 1, 2, 5, 6, and 8 than did aLPS from strain 19 (vaccine). The 2-D gel electrophoresis method was demonstrated to be of value in the analysis of aLPS from B. abortus and may be useful in the study of lipopolysaccharides from other sources.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 10 (1989), S. 223-237 
    ISSN: 0197-8462
    Keywords: geomagnetic field ; biogenic magnetite ; bacterial magnetotaxis ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Magnetotactic bacteria from freshwater and marine sediments orient and navigate along geomagnetic field lines. Their magnetotactic response is based on intracellular, single magnetic domains of ferrimagnetic magnetite, which impart a permanent magnetic dipole moment to the cell.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Polysaccharides ; Electrochemical detection ; Cu electrode ; Carbohydrates ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Complex polysaccharide mixtures were analyzed directly without derivatization by capillary zone electrophoresis in strongly alkaline solutions and electrochemical detection at a Cu electrode. The positively charged surfactant cetyltrimethylammonium bromide was included in the electrophoresis medium in order to reverse the electroosmotic flow and permit elution to be in order of increasing polysaccharide size. Carbohydrate samples analyzed by this approach included linear maltoses, enzymatically hydrolyzed starch, and commercially available dextrans of up to an average molecular weight of 18 300. Detection by constant-potential oxidation at a Cu electrode was very sensitive, with detection limits for individual carbohydrates generally below the femtomole level.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 2226-2232 
    ISSN: 0173-0835
    Keywords: Electrochemical detection ; Capillary electrophoresis ; Dual-parallel electrodes ; On-capillary electrodes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A new approach for dual electrode electrochemical detection in capillary electrophoresis (CEEC) is described. In this approach, two identical capillaries, each containing an on-capillary electrode incorporated permanently onto its tip, were paired together for simultaneous sample injection and detection. This procedure permitted dual-parallel detection to be performed without the need for painstaking alignment of the electrodes with respect to one another and to the capillary outlet as is required for the off-capillary microelectrode systems usually employed in CEEC. As a result, independent detection at two electrodes held at different potentials or at two electrodes of different composition or structure could be performed simply and with wide flexibility. Fabrication of on-capillary electrodes was carried out by sputter-coating the exit end of the capillaries with a thin layer of Au or Pt. Dual electrode system performance was demonstrated by separation and analysis of phenol and catechol samples. In addition, the detection system was coupled with glucose oxidase for the selective detection of glucose.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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