Paclitaxel-induced arterial wall toxicity and inflammation: tissue uptake in various dose densities in a minipig model.

PURPOSE: Paclitaxel is an antiproliferative agent in drug-eluting stents with largely unknown tissue interaction. Toxicity might result from overdosage and/or accumulation. Part 1 of this two-step study investigated how paclitaxel uptake depends on dose density, coronary drug transfer kinetics, and elution efficacy. MATERIALS AND METHODS: With cobalt chromium stents and Polyzene-F nanoscale coating, low, intermediate, and high paclitaxel dose densities (25 microg, 50 microg, and 150 microg per stent) were investigated in porcine right coronary arteries (RCAs). Coronary and myocardial tissue concentration measurements and determination of on-stent paclitaxel and plasma concentrations were performed at 2, 8, 24, and 72 hours. RESULTS: For all stents, uptake was similar at all time intervals (paclitaxel RCA concentration range, 1,610-33,300 ng). Low- and intermediate-dose stents showed similar RCA concentrations, but those for high-dose stents were three times greater. Residual on-stent paclitaxel concentration was not time-dependent, at 33.3% on low-, 30.6% on intermediate-, and 17.4% on high-dose stents. Paclitaxel was measurable in only the plasma immediately after stent placement, with a linear dose relationship and a timely regression: measurements in high-dose stents were 0.0454-0.656 ng/mL at 1 minute and 0.0329-0.0879 ng/mL at 5 minutes. Untreated control samples of the left coronary artery showed a linear dose-dependent concentration (12.6 ng/g, 21.2 ng/g, and 85.2 ng/g). CONCLUSIONS: Overall coronary paclitaxel uptake is fairly independent from the baseline overall dose density and, hence, depends on immediate binding mechanisms of the arterial wall. This is supported by the fact that, regardless of the applied dose density, the kinetics of paclitaxel uptake did not follow an exposure time pattern.

Prolonged bacterial culture to identify late periprosthetic joint infection: a promising strategy.

BACKGROUND: The value of microbiological culture to diagnose late periprosthetic infection is limited, especially because standard methods may fail to detect biofilm-forming sessile or other fastidious bacteria. There is no agreement on the appropriate cultivation period, although this period is a crucial factor. This study was designed to assess the duration of culture that is necessary for reliable detection. PATIENTS AND METHODS: Ten periprosthetic tissue specimens each were obtained during revision from 284 patients with suspected late hip or knee arthroplasty infection. Five samples were examined by microbiological culture over a 14-day period, and 5 were subjected to histologic analysis. To define infection, a pre-established algorithm was used; this included detection of indistinguishable organisms in >/=2 tissue samples or growth in 1 tissue sample and a positive result of histologic analysis (>5 neutrophils in at least 10 high-power fields). The time to detection of organisms was monitored. RESULTS: Infection was diagnosed in 110 patients. After 7 days (the longest incubation period most frequently reported), the detection rate via culture was merely 73.6%. Organisms indicating infection were found for up to 13 days. "Early"-detected species (mostly staphylococci) emerged predominantly during the first week, whereas "late"-detected agents (mostly Propionibacterium species) were detected mainly during the second week. In both populations, an unequivocal correlation between the number of culture-positive tissue samples and positive results of histologic analysis was noted, which corroborated the evidence that true infections were detected over the entire cultivation period. CONCLUSIONS: Prolonged microbiological culture for 2 weeks is promising because it yields signs of periprosthetic infection in a significant proportion of patients that would otherwise remain unidentified.

Analysis of pigmented villonodular synovitis with genome-wide complementary DNA microarray and tissue array technology reveals insight into potential novel therapeutic approaches.

OBJECTIVE: To characterize the gene expression profile and determine potential diagnostic markers and therapeutic targets in pigmented villonodular synovitis (PVNS). METHODS: Gene expression patterns in 11 patients with PVNS, 18 patients with rheumatoid arthritis (RA), and 19 patients with osteoarthritis (OA) were investigated using genome-wide complementary DNA microarrays. Validation of differentially expressed genes was performed by real-time quantitative polymerase chain reaction and immunohistochemical analysis on tissue arrays (80 patients with PVNS, 51 patients with RA, and 20 patients with OA). RESULTS: The gene expression profile in PVNS was clearly distinct from those in RA and OA. One hundred forty-one up-regulated genes and 47 down-regulated genes were found in PVNS compared with RA, and 153 up-regulated genes and 89 down-regulated genes were found in PVNS compared with OA (fold change > or = 1.5; Q < or = 0.001). Genes differentially expressed in PVNS were involved in apoptosis regulation, matrix degradation, and inflammation (ALOX5AP, ATP6V1B2, CD53, CHI3L1, CTSL, CXCR4, HSPA8, HSPCA, LAPTM5, MMP9, MOAP1, and SPP1). CONCLUSION: The gene expression signature in PVNS is similar to that of activated macrophages and is consistent with the local destructive course of the disease. The gene and protein expression patterns suggest that the ongoing proliferation in PVNS is sustained by apoptosis resistance. This result suggests the possibility of a potential novel therapeutic intervention against PVNS.