H.c Mei - Academia.edu (original) (raw)

Papers by H.c Mei

Fems Immunology and Medical Microbiology, 2006

Microbial adhesion of four bacterial and two yeast strains isolated from explanted voice prosthes... more Microbial adhesion of four bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber before and after conditioning with a biosurfactant obtained from the probiotic bacterium Streptococcus thermophilus A was investigated in a parallel plate flow chamber. The silicone rubber with and without an adsorbed biosurfactant layer was characterized using contact angle measurements. Water contact angles indicated that the silicone rubber surface with adsorbed biosurfactant was more hydrophilic (581) than bare silicone rubber (1091). The results obtained showed that the biosurfactant was effective in decreasing the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all microorganisms tested. A decrease in the initial deposition rate was observed for Rothia dentocariosa GBJ 52/2B and Staphylococcus aureus GB 2/1 from 1937 AE 194 to 179 AE 21 microorganisms cm À 2 s À 1 and from 1255 AE 54 to 233 AE 26 microorganisms cm À 2 s À 1 , respectively, accounting for an 86% reduction of the initial deposition rate for both strains. The number of bacterial cells adhering to the silicone rubber with preadsorbed biosurfactant after 4 h was further reduced by 89% and 97% by the two strains, respectively. The two yeast strains tested showed less reduction in adhesion after 4 h, to values between 67% and 70%. Such a pretreatment with surface-active compounds may constitute a promising strategy to reduce the microbial colonization rate of silicone rubber voice prostheses.

Science Translational Medicine, 2012

To cite this article: Y. Wang, G. Subbiahdoss, J. de Vries, M. Libera, H.C. van der Mei & H.J. Bu... more To cite this article: Y. Wang, G. Subbiahdoss, J. de Vries, M. Libera, H.C. van der Mei & H.J. Busscher (2012): Effect of adsorbed fibronectin on the differential adhesion of osteoblast-like cells and Staphylococcus aureus with and without fibronectin-binding proteins,

Biomaterial-associated-infection causes failure of biomaterial implants. Many new biomaterials ha... more Biomaterial-associated-infection causes failure of biomaterial implants. Many new biomaterials have been evaluated for their ability to inhibit bacterial colonization and stimulate tissue-cell-integration, but neglect the role of immune cells. This paper compares macrophage phagocytosis of adhering Staphylococcus aureus on cationic-coatings and patterned poly(ethylene)glycol-hydrogels versus common biomaterials and stainless steel in order to identify surface conditions that promote clearance of adhering bacteria. Staphylococci were allowed to adhere and grow on the materials in a parallel-plate-flow-chamber, after which murine macrophages were introduced. From the decrease in the number of adhering staphylococci, phagocytosis-rates were calculated, and total macrophage displacements during an experiment determined. Hydrophilic surfaces had the lowest phagocytosis-rates, while common biomaterials had intermediate phagocytosis-rates. Patterning of poly(ethylene)glycol-hydrogel coatings increased phagocytosis-rates to the level of common biomaterials, while on cationic-coatings phagocyto-sis-rates remained relatively low. Likely, phagocytosis-rates on cationic coatings are hampered relative to common biomaterials through strong electrostatic binding of negatively-charged macrophages and staphylococci. On polymeric biomaterials and glass, phagocytosis-rates increased with macrophage displacement, while both parameters increased with biomaterial surface hydrophobicity. Thus hydropho-bicity is a necessary surface condition for effective phagocytosis. Concluding, next-generation biomateri-als should account for surface effects on phagocytosis in order to enhance the ability of these materials to resist biomaterial-associated-infection.

The International Journal of Artificial Organs, 2012

Acrylates for bonding of joint prostheses and stainless-steel brackets in orthopedics and orthodo... more Acrylates for bonding of joint prostheses and stainless-steel brackets in orthopedics and orthodontics are prone to bacterial adhesion and biofilm formation, respectively, leading to serious infectious complications. Here we describe the preparation of a contact-killing acrylic resin by incorporation of [3-(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC). Physicochemical properties of the acrylates with and without MAPTAC incorporated were determined with X-ray photoelectron spectroscopy and water contact angles. The bond-strength of the acrylate with different percentages of MAPTAC was determined in a shear mode. The efficacy in contact-killing of the acrylate with MAPTAC incorporated with and without an adsorbed salivary coating was evaluated for various oral streptococcal strains. Cytotoxicity was tested against human skin fibroblasts. Acrylates with 16 wt% and 20 wt% incorporated MAPTAC showed strong contact-killing of various oral streptococcal strains up to challenge concentrations of 109 mL-1 within 15 min, with no elution of antimicrobial polymers. Contact-killing reduced after coating with a salivary conditioning film, but still remained significant up to a challenge concentration of 105 mL-1. No cytotoxicity of acrylate with incorporated MAPTAC was observed toward human skin fibroblasts. The bond strengths of stainless-steel brackets fixed to etched enamel through the resin (12 ± 3 MPa) decreased with increasing amounts MAPTAC to half of the original value when 20 wt% of MAPTAC was incorporated, which remained within a clinically acceptable range. These results suggest that MAPTAC can be effectively incorporated in orthodontic resin to provide long-term bactericidal activity against oral bacteria, with potential application in orthopedics.

Microscopy and Microanalysis, 2012

ABSTRACT Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, ... more ABSTRACT Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 2012.

Infection and Immunity, 2002

Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commen... more Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commensal microflora of the body, S. intermedius is often associated with deep-seated purulent infections, whereas S. mutans is frequently associated with dental caries. In this study, we investigated the roles of the S. mutans and S. intermedius antigen I/II proteins in adhesion and modulation of cell surface characteristics. By using isogenic mutants, we show that the antigen I/II in S. mutans, but not in S. intermedius, was involved in adhesion to a salivary film under flowing conditions, as well as in binding to rat collagen type I. Binding to human fibronectin was a common function associated with the S. mutans and S. intermedius antigen I/II. Adhesion of S. mutans or S. intermedius to human collagen types I or IV was negligible. Hydrophobicity, as measured by water contact angles, and zeta potentials were unaltered in the S. intermedius mutant. The S. mutans isogenic mutants, on the other hand, exhibited more positive zeta potentials at physiological pH values than did the wild type. The results indicate common and species-specific roles for the antigen I/II in mediating the attachment of S. mutans and S. intermedius to host components and in determining cell surface properties.

Journal of Dental Research, 2007

Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It r... more Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It requires the generation of strong fluid flows and the inclusion of air bubbles to become effective. A pair of co-adhering streptococci and actinomyces has been used previously to demonstrate non-contact removal by sonic brushing. Here we determined the influence of the sequence of co-adhesion of streptococci and actinomyces on non-contact removal from a salivary pellicle by rotary and sonic brushing. After bacterial adhesion, pellicles were brushed in a wet and immersed state, with a distance up to 4 mm to the bristle tips. Bacteria adhering to pellicles from the sequence streptococci followed by actinomyces appeared more difficult to remove and left more large co-aggregates than from the sequence actinomyces followed by streptococci. At contact, rotary and sonic brushing performed equally well in bacterial removal, while at 4 mm, both had lost some efficacy.

Fems Immunology and Medical Microbiology, 2006

Microbial adhesion of four bacterial and two yeast strains isolated from explanted voice prosthes... more Microbial adhesion of four bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber before and after conditioning with a biosurfactant obtained from the probiotic bacterium Streptococcus thermophilus A was investigated in a parallel plate flow chamber. The silicone rubber with and without an adsorbed biosurfactant layer was characterized using contact angle measurements. Water contact angles indicated that the silicone rubber surface with adsorbed biosurfactant was more hydrophilic (581) than bare silicone rubber (1091). The results obtained showed that the biosurfactant was effective in decreasing the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all microorganisms tested. A decrease in the initial deposition rate was observed for Rothia dentocariosa GBJ 52/2B and Staphylococcus aureus GB 2/1 from 1937 AE 194 to 179 AE 21 microorganisms cm À 2 s À 1 and from 1255 AE 54 to 233 AE 26 microorganisms cm À 2 s À 1 , respectively, accounting for an 86% reduction of the initial deposition rate for both strains. The number of bacterial cells adhering to the silicone rubber with preadsorbed biosurfactant after 4 h was further reduced by 89% and 97% by the two strains, respectively. The two yeast strains tested showed less reduction in adhesion after 4 h, to values between 67% and 70%. Such a pretreatment with surface-active compounds may constitute a promising strategy to reduce the microbial colonization rate of silicone rubber voice prostheses.

Science Translational Medicine, 2012

To cite this article: Y. Wang, G. Subbiahdoss, J. de Vries, M. Libera, H.C. van der Mei & H.J. Bu... more To cite this article: Y. Wang, G. Subbiahdoss, J. de Vries, M. Libera, H.C. van der Mei & H.J. Busscher (2012): Effect of adsorbed fibronectin on the differential adhesion of osteoblast-like cells and Staphylococcus aureus with and without fibronectin-binding proteins,

Biomaterial-associated-infection causes failure of biomaterial implants. Many new biomaterials ha... more Biomaterial-associated-infection causes failure of biomaterial implants. Many new biomaterials have been evaluated for their ability to inhibit bacterial colonization and stimulate tissue-cell-integration, but neglect the role of immune cells. This paper compares macrophage phagocytosis of adhering Staphylococcus aureus on cationic-coatings and patterned poly(ethylene)glycol-hydrogels versus common biomaterials and stainless steel in order to identify surface conditions that promote clearance of adhering bacteria. Staphylococci were allowed to adhere and grow on the materials in a parallel-plate-flow-chamber, after which murine macrophages were introduced. From the decrease in the number of adhering staphylococci, phagocytosis-rates were calculated, and total macrophage displacements during an experiment determined. Hydrophilic surfaces had the lowest phagocytosis-rates, while common biomaterials had intermediate phagocytosis-rates. Patterning of poly(ethylene)glycol-hydrogel coatings increased phagocytosis-rates to the level of common biomaterials, while on cationic-coatings phagocyto-sis-rates remained relatively low. Likely, phagocytosis-rates on cationic coatings are hampered relative to common biomaterials through strong electrostatic binding of negatively-charged macrophages and staphylococci. On polymeric biomaterials and glass, phagocytosis-rates increased with macrophage displacement, while both parameters increased with biomaterial surface hydrophobicity. Thus hydropho-bicity is a necessary surface condition for effective phagocytosis. Concluding, next-generation biomateri-als should account for surface effects on phagocytosis in order to enhance the ability of these materials to resist biomaterial-associated-infection.

The International Journal of Artificial Organs, 2012

Acrylates for bonding of joint prostheses and stainless-steel brackets in orthopedics and orthodo... more Acrylates for bonding of joint prostheses and stainless-steel brackets in orthopedics and orthodontics are prone to bacterial adhesion and biofilm formation, respectively, leading to serious infectious complications. Here we describe the preparation of a contact-killing acrylic resin by incorporation of [3-(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC). Physicochemical properties of the acrylates with and without MAPTAC incorporated were determined with X-ray photoelectron spectroscopy and water contact angles. The bond-strength of the acrylate with different percentages of MAPTAC was determined in a shear mode. The efficacy in contact-killing of the acrylate with MAPTAC incorporated with and without an adsorbed salivary coating was evaluated for various oral streptococcal strains. Cytotoxicity was tested against human skin fibroblasts. Acrylates with 16 wt% and 20 wt% incorporated MAPTAC showed strong contact-killing of various oral streptococcal strains up to challenge concentrations of 109 mL-1 within 15 min, with no elution of antimicrobial polymers. Contact-killing reduced after coating with a salivary conditioning film, but still remained significant up to a challenge concentration of 105 mL-1. No cytotoxicity of acrylate with incorporated MAPTAC was observed toward human skin fibroblasts. The bond strengths of stainless-steel brackets fixed to etched enamel through the resin (12 ± 3 MPa) decreased with increasing amounts MAPTAC to half of the original value when 20 wt% of MAPTAC was incorporated, which remained within a clinically acceptable range. These results suggest that MAPTAC can be effectively incorporated in orthodontic resin to provide long-term bactericidal activity against oral bacteria, with potential application in orthopedics.

Microscopy and Microanalysis, 2012

ABSTRACT Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, ... more ABSTRACT Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 - August 2, 2012.

Infection and Immunity, 2002

Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commen... more Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commensal microflora of the body, S. intermedius is often associated with deep-seated purulent infections, whereas S. mutans is frequently associated with dental caries. In this study, we investigated the roles of the S. mutans and S. intermedius antigen I/II proteins in adhesion and modulation of cell surface characteristics. By using isogenic mutants, we show that the antigen I/II in S. mutans, but not in S. intermedius, was involved in adhesion to a salivary film under flowing conditions, as well as in binding to rat collagen type I. Binding to human fibronectin was a common function associated with the S. mutans and S. intermedius antigen I/II. Adhesion of S. mutans or S. intermedius to human collagen types I or IV was negligible. Hydrophobicity, as measured by water contact angles, and zeta potentials were unaltered in the S. intermedius mutant. The S. mutans isogenic mutants, on the other hand, exhibited more positive zeta potentials at physiological pH values than did the wild type. The results indicate common and species-specific roles for the antigen I/II in mediating the attachment of S. mutans and S. intermedius to host components and in determining cell surface properties.

Journal of Dental Research, 2007

Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It r... more Non-contact plaque removal offers advantages in interproximal spaces, fissures, and pockets. It requires the generation of strong fluid flows and the inclusion of air bubbles to become effective. A pair of co-adhering streptococci and actinomyces has been used previously to demonstrate non-contact removal by sonic brushing. Here we determined the influence of the sequence of co-adhesion of streptococci and actinomyces on non-contact removal from a salivary pellicle by rotary and sonic brushing. After bacterial adhesion, pellicles were brushed in a wet and immersed state, with a distance up to 4 mm to the bristle tips. Bacteria adhering to pellicles from the sequence streptococci followed by actinomyces appeared more difficult to remove and left more large co-aggregates than from the sequence actinomyces followed by streptococci. At contact, rotary and sonic brushing performed equally well in bacterial removal, while at 4 mm, both had lost some efficacy.