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  • TCDD  (1)
  • bacteria  (1)
  • 1995-1999  (2)
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  • 1995-1999  (2)
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  • 1
    ISSN: 1572-9699
    Keywords: adhesion ; bacteria ; lactoferrin ; mucins ; saliva ; zeta potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The adhesion of Actinobacillus actinomycetemcomitans is a virulence factor in the aetiology of periodontitis and is determined by physico-chemical properties, e.g. surface charge and hydrophobicity, of the bacterial cell surface. Although oral surfaces are constantly coated with saliva, few studies have dealt with the binding of A. actinomycetemcomitans with saliva. In this report, the charge properties of A. actinomycetemcomitans have been studied through measurement of the zeta potential and the saliva-bacteria interaction investigated at different pH-values. At physiological conditions the zeta potential was negative, varying from -11 to -26 mV, for two laboratory and two fresh isolates of A. actinomycetemcomitans. Under these conditions, binding of the low-molecular-weight salivary mucin, lactoferrin, and S-IgA was confirmed using salivary samples and purified salivary fractions in liquid-phase and in ELISA. The iso-electric points of the laboratory and fresh clinical isolates of A. actinomycetemcomitans were determined at pH 4.6 and 3.8, respectively. At pH below the iso-electric point, giving positive values of the zeta potential, additional salivary protein species bound to A. actinomycetemcomitans, including the high-molecular-weight salivary mucin (MG1) and agglutinin. Binding of the low-molecular-weight salivary mucin (MG2), lactoferrin, and S-IgA, was hardly affected by this change in zeta potential. A salivary coating formed on the bacterium at pH 7 reduced the zeta potential of the laboratory strain Y4 greatly and an iso-electric point for the bacterium could not be determined. Overall, the study suggests that upon changes in environmental pH additional salivary attachment sites on the micro-organism are exposed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2959
    Keywords: mink ; otter ; organochlorines ; PLBS ; TCDD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract We investigated chlorinated hydrocarbon contaminants in aquatic mustelid species on the Fraser and Columbia Rivers of northwestern North America. Carcasses of river otter (Lutra canadensis) (N=24) and mink (Mustela vison) (N=34) were obtained from commercial trappers during the winters of 1990–91 and 1991–92. Pooled liver samples were analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), including non-ortho congeners, polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Most samples contained detectable concentrations of DDE, PCBs, although there was substantial variability in patterns and trends among neighboring samples. Concentrations of DDE were in some mink and several otter samples from the lower Columbia River elevated (to 4700 μg/kg wet weight); excluding one mink sample from the Wenatchee area, mean DDE levels generally decreased between 1978–79 and 1990–92. PCBs were present in all samples. PCB concentrations in otter livers collected from the lower Columbia were ten-fold lower than measured a decade previously; nevertheless, a sample taken near Portland had a mean concentration of 1500 μg/kg, within a range of concentrations associated with reproductive effects in captive mink. Concentrations of 2,3,7,8-TCDD and TCDF were generally below detection limits, except for one otter collected near a pulp mill at Castlegar, on the upper Columbia, with 11 ng TCDD/kg in liver. Elevated concentrations of higher chlorinated PCDD/Fs, probably resulting from use of chlorophenolic wood preservatives, were found in both species; one otter sample from the lower Columbia had 2200 ng OCDD/kg. International TCDD toxic equivalent levels in mink (31 ng/kg) and otter (93 ng/kg) from the lower Columbia River approached toxicity thresholds for effects on reproduction in ranch mink.
    Type of Medium: Electronic Resource
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