Publications by authors named "B Overdijk"

Human salivary chitinase could play a role in the defence against chitin-containing oral pathogens. The activity levels of chitinase in the whole saliva of periodontitis patients were significantly higher than those in saliva from controls. Periodontal treatment for a period of 5-6 months resulted in a three- to fourfold decrease in this enzyme activity.

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In recent studies the existence of a chitinase in various mammals, like man, was described. The aim of the present study was to find out whether salivas of periodontally healthy and inflamed humans also contain chitinase activity. Chitinase activity, assayed with the substrate 4-methylumbelliferyl-beta-D-N,N',N"-triacetylchitotrioside, was shown to be present in human whole saliva, with an activity level and apparent molecular mass (35 kDa) that were comparable with those of the human serum enzyme.

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Intravenous infection of guinea pigs with the fungus Aspergillus fumigatus resulted in increased levels of chitinase in serum and tissues of the animals. The molecular properties of the enzyme were demonstrated to be different from those of the fungal chitinase, but also from guinea pig lysozyme and beta-N-acetylhexosaminidase. Bio-Gel P-100 gel filtration showed that in liver, spleen, heart and lung tissue of control animals there were two molecular mass forms present with apparent molecular masses of 35 kDa and 15 kDa.

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The presence of chitinase activity in human serum has recently been described by us. On that occasion we speculated on the possible role of mammalian chitinases as a defense mechanism against chitin-containing pathogens. The results of the present study substantiate our hypothesis.

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Rat hepatocytes were incubated in the presence of a high concentration of the hepatopathogenic agent D-galactosamine (GalN), and the effect on the cellular concentrations of pyrimidine nucleotides and nucleotide sugars was determined. The UTP pool became depleted. The pools of UMP and CMP in RNA decreased to 72%, indicative for an inhibition of RNA synthesis.

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