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Biomedical subjects

C J van Oss

Publications and source records attributed to C J van Oss.

At least 19 recordsLinked to original sources
PubMed2001

Adsorption of biosurfactant on solid surfaces and consequences regarding the bioadhesion of Listeria monocytogenes LO28.

AIMS: The influence of biosurfactant compounds produced by a strain of Pseudomonas fluorescens on the adhesion of Listeria monocytogenes LO28 to polytetrafluoroethylene (PTFE) and AISI 304 stainless steel surfaces was investigated. METHODS AND RESULTS: The biosurfactant was produced according to a simple, novel technique based on cultivation on nutrient agar. Adhesion studies were performed using L. monocytogenes cells cultured at 20 or 37 degrees C. CONCLUSIONS: A substrate-dependent behaviour of the LO28 strain (larger number of cells adhering to stainless steel than to PTFE), and a significant reduction (< 90%) in microbial adhesion levels through the prior adsorption of biosurfactants on stainless steel surfaces, which can be related to a change in the electron-donor characteristics of this substratum, was demonstrated. SIGNIFICANCE AND IMPACT OF THE STUDY: The prior adsorption of biosurfactants on solid surfaces may constitute a new and effective means of combating the implantation of pathogenic micro-organisms in food processing plants.

Adsorption↗
PubMed1997

Adjuvancy effect of different types of silicone gel.

Women with silicone gel-filled breast implants (SBIs) are likely to be at a slightly higher risk of developing an autoimmune-like syndrome. This risk, although small, may be associated with the immunological adjuvancy property of the silicone gel. However, not all silicone gels are chemically formulated exactly the same and their adjuvancy behavior may vary. This study compared, in rats, the adjuvant effect of three different lots of silicone gel using ovalbumin (OVA) as the test antigen. Test bleeds were taken at 21, 48, 62, and 84 days post immunization and the rat sera were analyzed for anti-OVA antibodies by enzyme linked immunosorbent assay (ELISA). A delayed type hypersensitivity (DTH) test was performed on all the treated rats beginning at 14 post-immunization days. The results showed that silicone gel #3 (McGhan lot #S0400488) produced the highest mean anti-OVA antibody titer followed by silicone gel #1 (DC lot #HH019581) and silicone gel #2 (McGhan lot #DP9339). The DTH results showed that rats treated with silicone gel #1 and #3 had a clear positive response, whereas silicone gel #2 caused only a minimal response. These results demonstrate the immunological adjuvancy difference among three types of silicone gel. The chemical composition of each of these silicone gels, that would help explain these results, is yet to be determined.

Adjuvants, Immunologic↗
PubMed1997

Mechanisms of adjuvancy: I--Metal oxides as adjuvants.

The exact mechanism of how immune adjuvants function still remains largely unknown, despite their long history of use. This work reports the properties of alum and the related compounds Al(OH)3 or Al2O3. Experiments were performed in rats to determine the relative adjuvancy of silica, talc, ground glass, Al2O3, SnO2, ZrO2, hematite and magnetite. Antibody response and cell-mediated immunity (CMI) to ovalbumin (OVA) were determined and were found to be significantly enhanced by silica and talc. Antibody response to OVA was moderately enhanced by Al2O3, hematite, and magnetite, while CMI to OVA was not affected, SnO2, ZrO2, and ground glass only gave a slight adjuvant effect. The magnitude of adjuvancy appeared to correlate with the magnitude of the inflammatory response produced by each metal oxide and also correlated with their surface area. No correlation could be drawn between the hydrophilicity or hydrophobicity of the metal oxides and the magnitude of their adjuvancy.

Adjuvants, Immunologic↗
PubMed1996

Induction of type II collagen arthritis in the DA rat using silicone gel as adjuvant.

The Dark Agouti (DA) rat has been shown recently to have a high susceptibility for developing arthritis when challenged with either heterologous or homologous collagen II mixed with mineral oil, or with mineral oil challenge alone. This study determined the arthritogenic potential of silicone gel by either mixing it with bovine collagen II (BII) or by injecting silicone gel alone in DA rats. The incidence of collagen induced arthritis was as follows: PBS group- 0/10, silicone gel group- 4/10, and IFA group- 8/9. Anti-BII antibodies were formed in most of the rats treated with either silicone gel or IFA and these groups of rats showed a positive DTH reaction. The PBS treated rats were negative for both anti-BII antibodies and DTH reaction. The incidence of arthritis formation in rats injected with silicone gel alone was 0/10, while the IFA injected rats showed an incidence of 8/10. Silicone gel taken from a commercial breast implant thus is capable of mediating collagen induced arthritis in the DA rat. However, silicone gel alone does not appear to be arthritogenic.

Adjuvants, Immunologic↗
PubMed1995

Induction of type II collagen arthritis in the DA rat using silicone gels and oils as adjuvant.

The relative safety (or otherwise) of silicone gel filled breast implants remains a controversial issue. The Dark Agouti (DA) rat has been shown recently to have a high susceptibility for developing arthritis. This study determined the arthritogenic potential of silicone gel, silicone oil, and the low molecular weight octamethylcyclotetrasiloxane (D4), by either mixing it with bovine collagen II (BII) or by injecting silicone gel alone in DA rats. Three separate experiments were performed using 110 female DA rats with 10 rats per treatment group. The incidence of collagen induced arthritis was as follows: Experiment I (6 micrograms BII)- PBS = 0/10, silicone gel = 4/10, and IFA = 8/9; Experiment II (125 micrograms BII)- PBS = 0/10, silicone gel = 7/10, IFA = 10/10, 1,000 cs silicone oil = 3/10, D4 = 0/10, and 1% D4 in 1,000 cs silicone oil = 1/10; Experiment III (adjuvant alone)-IFA = 8/10, silicone gel = 0/10. Anti-BII antibodies were formed in most of the rats treated with either silicone gel or IFA mixed with BII and these groups of rats showed a positive DTH reaction. The PBS treated rats were negative for both anti-BII antibodies and DTH reaction. Silicone gel taken from a commercial breast implant thus is capable of mediating collagen induced arthritis in the DA rat. However, silicone gel alone does not appear to be arthritogenic.

Adjuvants, Immunologic↗
PubMed1995

The effect of silicone-gel on the immune response.

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Adjuvants, Immunologic↗
PubMed1994

Inactivation of the Porphyromonas gingivalis fimA gene blocks periodontal damage in gnotobiotic rats.

Fimbrial production by Porphyromonas gingivalis was inactivated by insertion-duplication mutagenesis, using the cloned gene for the P. gingivalis major fimbrial subunit protein, fimA. by several criteria, this insertion mutation rendered P. gingivalis unable to produce fimbrilin or an intact fimbrial structure. A nonfimbriated mutant, DPG3, hemagglutinated sheep erythrocytes normally and was unimpaired in the ability to coaggregate with Streptococcus gordonii G9B. The cell surface hydrophobicity of DPG3 was also unaffected by the loss of fimbriae. However, DPG3 was significantly less able to bind to saliva-coated hydroxyapatite than wild-type P. gingivalis 381. This suggested that P. gingivalis fimbriae are important for adherence of the organism to saliva-coated oral surfaces. Further, DPG3 was significantly less able to cause periodontal bone loss in a gnotobiotic rat model of periodontal disease. These observations are consistent with other data suggesting that P. gingivalis fimbriae play an important role in the pathogenesis of human periodontal disease.

Alveolar Bone Loss↗
PubMed1993

The adjuvant effect of silicone-gel on antibody formation in rats.

The extent of immunological adjuvancy of silicone-gel, from mammary implants, up to now, has not been determined definitively. This study compares the immune potentiation effects of silicone-gel with that of Freund's adjuvant, using bovine serum albumin (BSA) as the test antigen in rats. Sixty, 250 gr., male Sprague Dawley rats were divided into six groups: I- phosphate buffered saline (PBS) only, II- silicone oil (Dow Corning Medical Grade 360 liquid silicone), III- 50% silicone-gel (McGhan Medical Corp.- mammary implant) in silicone oil, IV- complete Freund's adjuvant (CFA), V- incomplete Freund's adjuvant (IFA), and VI- 50% silicone oil in IFA. Each adjuvant was mixed or emulsified with an equal volume of 50 micrograms of BSA in 150 microliters of PBS. Each immunization was given intramuscularly in a single injection. Cardiac puncture test bleeds were taken at 12, 22, 40 and 56 days post immunization and the serum anti-BSA-antibody was measured by ELISA. The results indicate that silicone-gel is a potent immunological adjuvant, compared to both CFA and IFA. Silicone oil alone is not as potent as adjuvant and seems to inhibit the immune response when mixed with IFA. There thus appears to be a distinct possibility that silicone-gel may also be able to mediate an auto-immune reaction.

Animals↗
PubMed1992

The effect of hydrophilicity-hydrophobicity and solubility on the immunogenicity of some natural and synthetic polymers.

The general effects of solubility and hydrophobicity-hydrophilicity on the immunogenicity of synthetic and natural polymers are presented. The degree of hydrophobicity or hydrophilicity was determined from contact angle measurements. The surface tension components, obtained from the contact angles, were then correlated with the degree of immunogenicity for each substance. The results indicate that highly hydrophobic and highly hydrophilic polymers are not immunogenic. Moderate hydrophobicity as well as moderate hydrophilicity, and solubility in water favor immunogenicity (provided the molecular mass be at least 10,000 Da). For example, the solubilization of zein (a hydrophobic insoluble maize protein) prior to immunization causes zein to become immunogenic.

Animals↗
PubMed1991

The generation of antibody in mice to tuftsin: a naturally occurring phagocytosis stimulating tetrapeptide.

Tuftsin (Thr-Lys-Pro-Arg) is a naturally occurring tetrapeptide that stimulates most known functions of the polymorphonuclear leukocyte and macrophage cell lines. We previously reported our unsuccessful attempts to generate antituftsin antibodies by conjugating tuftsin to several carrier proteins and by polymerizing the peptide with glutaraldehyde. To render tuftsin antigenic the following modifications were made to native tuftsin: three glycine residues were added to the N terminus of tuftsin (Gly3-tuf) and cysteine was added to the N terminus (Cys-tuf) and to the C terminus (tuf-Cys). Native tuftsin was covalently conjugated to sheep red blood cells (SRBC). In a separate experiment Balb/c mice primed with SRBC were immunized with 10(7) SRBC peptide conjugate. Native tuftsin and Gly3-tuf were also conjugated to keyhole limpet hemocyanin (KLH). In another experiment KLH and cationized bovine serum albumin (cBSA) were activated with sulfo-succinimidyl 4-(N-maleimidomethyl)cyclohexane-1-carboxylate (s-SMCC), which was used to control orientation of tuf-Cys and Cys-tuf when conjugated to each carrier protein. All conjugates were administered in complete Freund's adjuvant (CFA) except for cBSA conjugates which were administered in alum. Antibody response was determined by solid phase radioimmunoassay. Results showed that specific antituftsin antibodies were elicited only by Cys-tuf, conjugated to KLH. This study reaffirms that tuftsin is weakly antigenic and confirms the previous work by Gottlieb et al. that antibody to tuftsin can only be elicited when tuftsin is conjugated to the carrier protein KLH in a manner that leaves the peptide carboxyl end free.

Amino Acid Sequence↗
PubMed1990

Aspecific and specific intermolecular interactions in aqueous media.

Aspecific as well as specific interactions involve the same noncovalent forces, consisting of Lifshitz-van der Waals, Lewis acid/base, electrostatic, and thermal or Brownian movement interactions. In vivo, aspecific interactions between, e.g., cells and/or biopolymers usually are repulsive, while specific interactions are always attractive. The differences between the two classes of interactions can be shown to lie in the fact that aspecifically interacting bodies are large, while specifically interacting sites are small, or have a small radius of curvature, and in the fact that aspecifically interacting surfaces are homogeneous, whereas specific sites have a heterogeneous composition.

Binding Sites↗
PubMed1990

Surface properties of fibrinogen and fibrin.

By contact angle measurements on layers of fibrinogen and fibrin, it can be shown that the transformation from fibrinogen to fibrin is accompanied by a change in surface properties from very hydrophilic (fibrinogen) to moderately but definitely hydrophobic (fibrin). It is also shown that, contrary to serum albumin and gamma globulin, fibrinogen does not become more hydrophobic upon drying.

Animals↗
PubMed1990

Depletion flocculation and depletion stabilization of erythrocytes.

At dextran (Mw approximately 500,000) concentrations from 2 to approximately 10%, suspensions of normal human erythrocytes flocculate in small convex agglutinates. At dextran concentrations greater than 10%, the erythrocytes resegregate in a stable monodisperse suspension. At all these dextran concentrations, the erythrocytes are coated with considerable amounts of dextran. It can be argued that at dextran concentrations from 2 to 10%, as well as at dextran concentrations greater than 10%, there is a thin layer, which is depleted of dextran, between the dextran layer adsorbed onto the erythrocytes and the bulk dextran solution. It can also be shown that there is a repulsive interaction between the two layers of dextran: one adsorbed and one free. When the adsorbed dextran layer is the most concentrated, stability must ensue, and when the dextran in free solution is the most concentrated, flocculation should occur. Below 7% dextran, the concentration of free dextran is higher than the adsorbed concentration; above 10% dextran that situation is reversed. These data correlate well with the depletion flocculation predicted for the lower concentration and the depletion stabilization predicted for the higher dextran concentration.

Biophysical Phenomena↗