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Biomedical subjects

K Yuan

Publications and source records attributed to K Yuan.

26 records · Page 2Linked to original sources
PubMed1994

Adherence of oral microorganisms to guided tissue membranes: an in vitro study.

Microorganisms can adhere and colonize on an exposed guided tissue regeneration (GTR) membrane thus developing a nidus of infection. The purpose of this study was to compare early bacterial adhesion to three different GTR membranes. Expanded polytetrafluoroethylene, polyglactin 910, and collagen were used as the test membranes. In part I of this study 15 different oral microbes were used to compare their relative ability to adhere to the membranes. Six of the most strongly adherent bacteria (Actinomyces viscosus, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Streptococcus mutans, Fusobacterium nucleatum, and Selenomonas sputigena) were selected for part II of this study. The membranes were placed in tubes containing broth cultures containing identical concentrations (1 x 10(8) cells/ml) of these bacteria at 37 degrees C. Membranes were placed in tubes of media without bacteria as controls. At 4, 6, 12, and 24 hours, the bacterial cultures were decanted and the membranes in the tubes were agitated gently in reduced transfer fluid (RTF) 4 times to remove non-adherent bacteria. Each tube was then sonicated for 30 seconds in 10 ml RTF to detach adherent bacteria. The detached adherent bacteria were counted using a Petroff-Hausser chamber. Data were analyzed by using the SAS program. Analysis of variance was used to test for differences between multiple means. Results showed S. mutans had the strongest attachment to the collagen membrane at 4 and 6 hours. Selenomonas sputigena had the lowest adherence capability to all test membranes. Polyglactin 910 had significantly (P < 0.05) lower S. mutants adherence than either the ePTFE or the collagen membrane at 4 and 6 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces viscosus↗
PubMed1981

Comparison of various properties of low-molecular-weight proteins from dormant spores of several Bacillus species.

Several properties of the major proteins degraded during germination of spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis have been compared. All of the proteins had low molecular weights (6,000 to 13,000) and lacked cysteine, cystine, and tryptophan. The proteins could be subdivided into two groups: group I (B. megaterium A and C proteins, B. cereus A protein, and B. subtilis alpha and beta proteins) and group II (B. cereus and B. megaterium B proteins and B. subtilis gamma protein). Species in group II had lower levels of (or lacked) the amino acids isoleucine, leucine, methionine, and proline. Similarly, proteins in each group were more closely related immunologically. However, antisera against a B. megaterium group I protein cross-reacted more strongly with the B. megaterium group II protein than with group I proteins from other spore species, whereas antisera against the B. megaterium group II protein cross-reacted most strongly with B. megaterium group I proteins. Analysis of the primary sequences at the amino termini and in the regions of the B. cereus and B. subtilis proteins cleaved by the B. megaterium spore protease revealed that the B. cereus A protein was most similar to the B. megaterium A and C proteins, and the B. cereus B protein and the B. subtilis gamma protein were most similar to the B. megaterium B protein. However, amino terminal sequences within one group of proteins varied considerably, whereas the spore protease cleavage sites were more highly conserved.

Amino Acid Sequence↗