Comparison of single-stage and delayed gastrocnemius flap procedures for soft-tissue defects of the knee and proximal tibia.

PURPOSE: Gastrocnemius flaps provide reliable reconstructive solutions to soft-tissue loss of the knee and proximal tibia following orthopedic procedures. While this technique has been used and studied, little is known about its prophylactic application. Single-stage and delayed approaches were compared with respect to the timing of débridement, complications, and relationship between microorganisms and complications. METHODS: Gastrocnemius flaps for soft-tissue defects of the knee joint were retrospectively reviewed. Success of the flap procedure was defined as a healed soft-tissue envelope, no evidence of infection, a good blood supply to the flap, and adherence of the flap to its bed. Independent sample t test was used to compare the corresponding parameters (level of statistical significance was 0.05). RESULTS: Of 43 flaps (43 patients), 18 were performed during a single-stage procedure along with the orthopedic procedure and 25 were delayed. Success of the single-stage (100%) and delayed flaps (88%) was not significantly different (p = 0.083). Complication rate did not differ significantly for single-stage (11%) and delayed flaps (24%) (p = 0.272). We were unable to establish a relationship between complications and microorganisms. CONCLUSION: Results indicate both approaches are reliable. Single-stage gastrocnemius flaps may eliminate the need for a second surgery. LEVEL OF EVIDENCE: Level III (Therapeutic, Retrospective cohort).

Using Ligand-Accelerated Catalysis to Repurpose Fluorogenic Reactions for Platinum or Copper.

The development of a fluorescent probe for a specific metal has required exquisite design, synthesis, and optimization of fluorogenic molecules endowed with chelating moieties with heteroatoms. These probes are generally chelation- or reactivity-based. Catalysis-based fluorescent probes have the potential to be more sensitive; however, catalytic methods with a biocompatible fluorescence turn-on switch are rare. Here, we have exploited ligand-accelerated metal catalysis to repurpose known fluorescent probes for different metals, a new approach in probe development. We used the cleavage of allylic and propargylic ethers as platforms that were previously designed for palladium. After a single experiment that combinatorially examined >800 reactions with two variables (metal and ligand) for each ether, we discovered a platinum- or copper-selective method with the ligand effect of specific phosphines. Both metal-ligand systems were previously unknown and afforded strong signals owing to catalytic turnover. The fluorometric technologies were applied to geological, pharmaceutical, serum, and live cell samples and were used to discover that platinum accumulates in lysosomes in cisplatin-resistant cells in a manner that appears to be independent of copper distribution. The use of ligand-accelerated catalysis may present a new blueprint for engineering metal selectivity in probe development.