M van Raamsdonk

Academisch Centrum Tandheelkunde Amsterdam, Amsterdam, North Holland, Netherlands

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Publications (5)16.19 Total impact

  • M van Raamsdonk, J J de Soet, C L Jones, J de Graaff
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    ABSTRACT: Passive immunization has been suggested as a method to prevent colonization of teeth by mutans streptococci. However, the mechanism of action of antibodies, both polyclonal and monoclonal, is not clear. In this study we investigated the effect of polyclonal antibodies (pAbs) and a monoclonal antibody (OMVU10) on the chain length and growth of Streptococcus sobrinus. During growth in broth S. sobrinus formed significantly longer chains in the presence of pAbs in comparison to pre-immune serum (p < 0.01), but pAbs did not influence the growth rate of S. sobrinus in broth. OMVU10 did not influence the growth rate nor the chain length. In order to study the effect of the antibodies on adhesion and growth on a surface, S. sobrinus was grown on hydroxyapatite discs in the presence of two other bacteria, Streptococcus oralis and Actinomyces viscosus. No effect of the antibodies was found on the total cultivable count of the three bacteria after growth on hydroxyapatite discs. However, the morphology of the S. sobrinus microcolonies was different after growth in the presence of both pAbs and OMVU10. The colonies were less dense and chains of S. sobrinus could be seen using a confocal laser microscope. After growth in the presence of the control antibodies, the colonies were dense and no long chains could be observed. It was concluded that pAbs influenced the chain length, in broth and on hydroxyapatite discs, and the colony morphology of S. sobrinus on hydroxyapatite discs, whereas OMVU10 influenced the colony morphology of S. sobrinus on hydroxyapatite discs.
    Caries Research 01/1997; 31(1):35-40. · 2.51 Impact Factor
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    ABSTRACT: The effect of a polyclonal antiserum and OMVU10, a monoclonal antibody reactive with Antigen B of Streptococcus sobrinus, on the interaction of polymorphonuclear leukocytes with S. sobrinus was studied, using chemiluminescence and bacterial killing assays. Increased stimulation of neutrophils as measured in the chemiluminescence assays was established when S. sobrinus was preincubated with polyclonal antiserum or when polyclonal antiserum was added to the reaction mixture. Higher counts were measured in comparison to preimmune serum. After 90 min, 52% of S. sobrinus preincubated with polyclonal antiserum was killed. Killing was also increased when polyclonal antiserum was added to the reaction mixture in comparison to the controls. No killing was found when bacteria were preincubated with OMVU10 or when OMVU10 was added to the reaction mixture in comparison to Clone 24, a control antibody.
    Oral Microbiology and Immunology 09/1996; 11(4):254-8. · 2.81 Impact Factor
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    ABSTRACT: In this study, the effect of antibody adsorption on physicochemical properties of Streptococcus sobrinus was studied. Bacteria were preincubated with polyclonal antibodies or with OMVU10, a monoclonal antibody (MAb) reactive with S. sobrinus. The zeta potentials and the hydrophobicity as determined by microbial adhesion to hydrocarbons were measured in potassium phosphate buffer with a pH ranging from 2 to 9. S. sobrinus preincubated with polyclonal antibodies was positively charged at pH 2, 3, and 4 and had an isoelectric point at pH 4.8. Untreated S. sobrinus cells or cells preincubated with MAbs were negatively charged over the whole pH range. X-ray photoelectron spectroscopy showed a decrease in O/C and P/C ratios for bacteria preincubated with polyclonal antibodies. A combination of the pH-dependent zeta potential and the X-ray photoelectron spectroscopy data of the overall chemical composition of the cell surface suggests that polyclonal antibody adsorption occurs through blocking of surface phosphate. The measurement of hydrophobicity by microbial adhesion to hydrocarbons revealed that S. sobrinus preincubated with polyclonal antibodies was hydrophobic (90% of the bacteria bound to hexadecane), whereas the controls were relatively hydrophilic. S. sobrinus preincubated with OMVU10 was found to be more hydrophobic than the controls at pH 5 and 7. Hydrophobicity as measured by water contact angles showed an increase in hydrophobicity when S. sobrinus was preincubated with polyclonal antibodies. The epitopes to which the antibodies are directed were visualized by immunogold labeling and electron microscopy. The results suggested that OMVU10 is reactive with only a few epitopes of the cell surface, whereas polyclonal antibodies were found to be reactive with many epitopes. In conclusion, adsorption of polyclonal antibodies was found to influence the overall physicochemical surface properties of the organism, probably by forming a coating over the whole cell surface. Adsorption of MAbs was more localized, which could explain their lesser influence on these surface properties.
    Infection and Immunity 06/1995; 63(5):1698-702. · 4.07 Impact Factor
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    ABSTRACT: Deposition of the oral bacteriumStreptococcus sobrinus HG977 onto glass (water contact angle 0°) and onto FEP-Teflon (fluoroethylenepropylene; water contact angle 110°) was studied in a parallel-plate flow chamber in the presence and absence of polyclonal antibodies (pAb) and monoclonal antibodies (mAbs) adsorbed onto the cells. The zeta potentials of the bacteria ranged from −7.1 to −8.5 mV at pH 6.8 and were not affected by the presence of pAb or mAbs. Hydrophobicity (by water contact angles) increased from 30° (no antibodies) to 88° in the presence of pAb adsorbed onto the bacterial cell surface. The untreatedS. sobrinus had a greater tendency to adhere to glass (44.5 × 106 cm−2) than to FEP-Teflon (18.3 × 106 cm−2), in accordance with thermodynamic modelling. After preincubation ofS. sobrinus with pAb, its clear preference for adhesion to glass disappeared as expected from its increased hydrophobicity. Although forS. sobrinus preincubated with OMVU10 no difference was found in hydrophobicity in comparison to the untreated bacteria, the number of bacteria adhering to glass decreased to 10.2 ¢ 106 cm−2. Formation of bacterial aggregates was found whenS. sobrinus, preincubated with pAb or OMVU10, adhered to glass and FEP. This was also observed when untreated bacteria adhered to glass coated with OMVU10, or to FEP coaled with OMVU10 or pAb. Adhesion in these experiments is therefore thought to occur via near-neighbour collection induced by the presence of pAb or mAbs. Low numbers of bacteria were removed from glass after draining the flow cell, whereas high numbers of untreated bacteria and bacteria preincubated with OMVU10 were removed from FEP.S. sobrinus cells preincubated with pAb were not removed but piled up. It was concluded that the adhesion of untreatedS. sobrinus andS. sobrinus preincubated with pAb is in accordance with thermodynamic modelling, based on the overall wettability of the cell surfaces, whereas the adhesion ofS. sobrinus preincubated with OMVU10 may be through localized interactions, not expressed in overall surface properties.
    Colloids and surfaces B: Biointerfaces 01/1995; 4(6):401-410. · 4.28 Impact Factor
  • M van Raamsdonk, J J de Soet, J de Graaff
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    ABSTRACT: Local passive immunization has been suggested as a method of preventing colonization of teeth by mutans streptococci. In this study we describe the effect of local application of monoclonal antibodies (Mabs) on the colonization of Streptococcus sobrinus. The rats, 37 days old, were divided in 4 groups: group 1 received Mab OMVU10 (Mab reactive with Antigen B of S. sobrinus, IgG2b), group 2 received Clone 24 (Mab reactive with lipid A of Escherichia coli, IgG2b), group 3 received uninoculated culture medium, and group 4 received phosphate-buffered saline (PBS). Mabs were applied 6 times on the surfaces of the molars and the labial surfaces of the incisors of the rats, on days 37, 40, 44, 46, 49 and 54 after birth. After the third application of Mabs, all rats were inoculated with S. sobrinus (day 45). Subsequently, the rats were fed a cariogenic diet containing 20% sucrose and 5% glucose. The rats were killed 34 days after inoculation and the maxillary molars were extracted and homogenized in order to determine the numbers of S. sobrinus. The proportions of S. sobrinus, expressed as a percentage of the total cultivable microflora, in rats which received OMVU10 (group 1) were 23.1 +/- 14.8%, whereas in rats which received Clone 24, culture medium or PBS the levels were 34.5 +/- 11.3%, 40.7 +/- 14.9% and 36.7 +/- 9.7%, respectively. Statistical analysis showed that the level of colonization of rats which received OMVU10 was significantly lower than that of rats which received Clone 24, culture medium or PBS (p < 0.001, p < 0.013 and p < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
    Caries Research 01/1993; 27(1):31-7. · 2.51 Impact Factor