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  • 1
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 58 (1993), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Traditional frying produced mutagens in a dose-dependent manner (0.5–4.0g equivalents of beefburger extract) as detected by Salmonella typhimutium strains TA97 and TA98 (sensitive to frame-shift mutagens). Mutagenicity was associated with beefburger crusts. In beef burgers cooked by microwave, in presence or absence of browning agent and flavoring, bacterial mutagens were not detected at equivalent dose concentrations. In addition to reduction of mutagen formation, microwave cooking produced an equally acceptable product as judged by limited flavor testing.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Aspergillus fumigatus, the most common cause of invasive pulmonary aspergillosis (IPA), produces a potent cytotoxjn called restrictocin. To investigate the role of restrictocin in (PA, we have constructed fungal strains in which the res gene has been inactivated by gene disruption. These disruptants lack the specific extracellular ribonucleolytic activity associated with restrictocin, as measured by an in vitro rabbit reticulocyte lysate assay. Western blot analysis of one drsruptant, using an anti-restrictocin monoclonal antibody, confirmed that the toxin is not produced. The growth characteristics of the disruptants could not be distinguished from those of their parental isolates on a variety of culture media. The pathogenicity of two disruptants was assessed in a murine model of IPA. There were no significant differences in mortality when these strains were compared with the parental isolates and an ectopic transformant. In addition, histological examination of infectediung tissue did not reveal any obvious differences in the number or size of fungal colonies or in the polymorphonuclearleucocyte response. Our results demonstrate that restrictocin is not an important virulence factor in this model of IPA.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Two-dimensional gel electrophoresis was used to follow low changes in gene expression associated with antibiotic (bialaphos) biosynthesis in Streptomyces hygroscopicus. Cultures were pulse-labelled with [35S]-methionine before, during, and after the switch from primary to secondary metabolism in order to compare kinetic profiles of bialaphos (antibiotic) production (bap) genes during this metabolic transition. Separation of gene products on two-dimensional gels revealed that 27 were dependent on brpA for optimal expression and were activated as the culture approached stationary phase. Genes which encoded 10 brp4-dependent proteins were mapped to a 10 kb Sstl fragment of the 35 kb bap gene cluster by expressing them in Streptomyces lividans using the thiostrepton-inducible tipA promoter. N-terminal amino acid sequences of two brpA-dependent proteins, obtained by direct microsequencing of protein spots excised from two-dimensional gels, identified them as gene products mapping to the same region and involved in secondary metabolic conversions of the bap pathway. The kinetics of synthesis of 16 brpA-dependent gene products were characterized using QUEST computer software. Cluster analysis performed on the kinetics of synthesis of 346 of the most highly expressed gene products of HP5-29, including 16 brpA-dependent ones, identified 75 families having distinct patterns of expression. Many brpA-dependent proteins were clustered together; 10 were found in one kinetic family. These kinetic families also included brpA-independent gene products perhaps subject to similar regulatory mechanisms and thus possibly involved in bialaphos biosynthesis. The activation/derepression of bap expression took place as cultures approached stationary phase and was temporally related to synthesis of ppGpp.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 5 (1994), S. 467-472 
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: There is growing concern regarding the possible effects of prolonged body exposure to trace amounts of metals, The high corrosion resistance of titanlum and its alleys is resulting in their more widespread use. Passivation of these metals using HNO3 according to ASTM F86 is based on the assumption that this will produce an increased resistance to corrosion, but its effects do not appear to have been examined at the trace element level. We have used sensitive graphite furnace atomic absorption spectrophotometry to examine in vitro the influence of such passivation on the release of Ti, Al and V from Ti6Al4V and solid cpTi into serum-containing culture medium during incubation for 9 days. We detected a highly significant increase in the trace levels of Ti, Al and V in medium samples from passivated Ti6Al4V compared to those obtained from non-passivated Ti6Al4V; in addition, there was a significant time-related decrease in these levels, as well as in the levels observed in medium samples from the non-passivated Ti6Al4V controls and from passivated and non-passivated cpTi.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 11 (1991), S. 299-300 
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 20 (1994), S. 193-194 
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 8 (1990), S. 187-197 
    ISSN: 1573-1111
    Keywords: SO2-Hydroquinone clathrate ; SO2-β-quinol clathrate ; dielectric ; solid state13C NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dielectric measurements of SO2 quinol clathrates show that the reorientation of encaged SO2 molecules is very rapid and depends greatly on the degree of cage occupancy. For aβ-quinol sample of cage occupancyθ = 0.57, the reorientation rate was ∼ 1 MHz at 6 K, with a reorientational activation energy of 673 J/mol. For a sample identified by13C NMR asα-quinol, and for aβ-quinol sample with most cages filled with Xe, SO2 reorientation rates are even greater, with activation energies of only some tens of J/mol. The low temperature dielectric studies show that some ethanol may be enclathrated inβ-quinol recrystallized from this solvent. The13C NMR spectra confirm the X-ray results that the lattice becomes distorted with increased SO2 content.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 851-859 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Primary bone cells, isolated from the periosteally stripped calvariae of neonate rats, were cultured on 60Co γ-irradiation-sterilized bacteriologic-grade polystyrene that had been either surface treated with concentrated sulfuric acid or received further γ-irradiation treatments facilitated cell colonization of the polystyrene compared to those surfaces not treated in the laboratory. x-Ray photoelectron spectroscopy (XPS) showed that the two treatments introduced different chemical groups onto the polymer surface and that cell adhesion was related to γ-irradiation in a dose-dependent manner. These results show that simple biologic assays, such as cell colonization, are not able to distinguish between differences in surface chemistry demonstrated by such a routinely employed surface analysis technique. Thus, there is a need to develop more sensitive biologic assays that provide functional information of a precision that can be correlated with subtle changes in substratum surface chemistry. Further, we argue that because cells isolated by tissue digestion using proteolytic enzymes respond more readily to changes in the surface chemistry of the substratum they colonize, compared to explanted cells; biologic assays designed for biomaterials testing must take into account changes effected in cell adhesion behavior by isolation procedures. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 105-112 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cell-mediated resorption of densely sintered hydroxyapatite (HA1250), tricalcium phosphate (TCP), and 600° or 900°C calcined hydroxyapatite (HA600 and HA900, respectively), was investigated by using two culture systems. The first was an osteoclastic cell culture, and the second was a two-stage culture that was composed of a bonelike tissue formation on the substrata in the first stage and its subsequent resorption by osteoclasts in the second stage. Neither of the materials showed resorption or surface alterations in the osteoclastic cell culture, except for some limited phagocytotic activity on HA600 and HA900. In the two-stage culture, production of mineralized extracellular matrix was only observed on HA1250 and TCP, and its subsequent resorption by osteoclastlike cells was evident. Small and occasionally larger tartrate-resistant acid phosphatase positive cells produced 20-150 μm diameter resorption pits in both the mineralized extracellular matrix on HA1250 and TCP and TCP and the surfaces of HA600 and HA900. Resorption of the mineralized extracellular matrix on TCP also resulted in degradation of the underlying ceramic surface, mainly initiating from intergrain boundaries, whereas the surface of HA1250 remained unaltered. The results of this study clearly demonstrate that osteoclastic resorption of calcium phosphates is potentiated in postosteogenic culture conditions. A possible role for bone matrix constituents in cell-mediated resorption is hypothesized, whereas the occurrence of resorption seems to be mainly governed by the combined effects of material characteristics such as grain size and crystal structure. © 1994 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
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