A new antibacterial carrier of hyaluronic acid gel.

BACKGROUND: Postoperative infection following total joint arthroplasty is thought to be one of the most serious and devastating complications. To develop an effective treatment for this complication, we tested a bioabsorbable antibacterial carrier that is made from novel cross-linked hyaluronic acid (HA) gel and gentamicin (GM). METHODS: Antibacterial activity of the carrier was evaluated by the agar diffusion test, direct contact test, in vivo mouse model, and in vivo rabbit osteomyelitis model. RESULTS: GM-containing HA gel suppressed bacterial growth both in vitro and in vivo. In the rabbit osteomyelitis model, beads coated with HA gel containing GM did not disturb bone ongrowth in the femoral stem. CONCLUSIONS: Our bioabsorbable carrier of antibiotic-containing HA gel is effective for prophylactic treatment or treatment of an actual deep infection following total joint arthroplasty.

Antibiotic-containing hyaluronic acid gel as an antibacterial carrier: Usefulness of sponge and film-formed HA gel in deep infection.

We have developed a novel bioabsorbable antibacterial carrier using hyaluronic acid (HA) gel for prevention and treatment of orthopedic infections. In this study, we investigated the in vivo antibacterial effects of two forms of this new material, an HA gel sponge and an HA gel film. A titanium cylinder was inserted into the intramedullary cavity of each rabbit femur, along with an HA gel sponge or HA gel film containing antibiotics. The HA gel sponge contained gentamycin, vancomycin, tobramycin, or minomycin. The HA gel film contained gentamycin or vancomycin. After 0, 7, and 14 days, the rabbit bone marrow was collected, and the antibacterial activity of the HA gel was determined by agar diffusion test. As a control, we used Septocoll, a commercially available antibacterial carrier. Both the HA gel sponge and HA gel film exhibited antibacterial activity. The present results indicate that HA gel containing antibiotics is a clinically useful bioabsorbable antibacterial carrier.

Inhibition of hyaluronan synthesis in Streptococcus equi FM100 by 4-methylumbelliferone.

As observed previously in cultured human skin fibroblasts, a decrease of hyaluronan production was also observed in group C Streptococcus equi FM100 cells treated with 4-methylumbelliferone (MU), although there was no effect on their growth. In this study, the inhibition mechanism of hyaluronan synthesis by MU was examined using Streptococcus equi FM100, as a model. When MU was added to a reaction mixture containing the two sugar nucleotide donors and a membrane-rich fraction as an enzyme source in a cell-free hyaluronan synthesis experiment, there was no change in the production of hyaluronan. On the contrary, when MU was added to the culture medium of FM100 cells, hyaluronan production in the isolated membranes was decreased in a dose-dependent manner. However, when the effect of MU on the expression level of hyaluronan synthase was examined, MU did not decrease either the mRNA level of the has operon containing the hyaluronan synthase gene or the protein level of hyaluronan synthase. Solubilization of the enzyme from membranes of MU-treated cells and addition of the exogenous phospholipid, cardiolipin, rescued hyaluronan synthase activity. In the mass spectrometric analysis of the membrane phospholipids from FM100 cells treated with MU, changes were observed in the distribution of only cardiolipin species but not of the other major phospholipid, PtdGro. These results suggest that MU treatment may cause a decrease in hyaluronan synthase activity by altering the lipid environment of membranes, especially the distribution of different cardiolipin species, surrounding hyaluronan synthase.

Stereoselective Reduction of Ethyl 4-Chloro-3-Oxobutanoate by a Microbial Aldehyde Reductase in an Organic Solvent-Water Diphasic System.

Enzyme-catalyzed asymmetric reduction of ethyl 4-chloro-3-oxobutanoate in an organic solvent-water diphasic system was studied. NADPH-dependent aldehyde reductase isolated from Sporobolomyces salmonicolor AKU4429 and glucose dehydrogenase were used as catalysts for reduction of ethyl 4-chloro-3-oxobutanoate and recycling of NADPH, respectively, in this system. In an aqueous system, the substrate was unstable. Inhibition of the reaction and inactivation of the enzymes by the substrate and the product were also observed. An n-butyl acetate-water diphasic system very efficiently overcame these limitations. In a 1,600-ml-1,600-ml scale diphasic reaction, ethyl (R)-4-chloro-3-hydroxybutanoate (0.80 mol; 86% enantiomeric excess) was produced from the corresponding oxoester in a molar yield of 95.4% with an NADPH turnover of 5,500 mol/mol.