Figure 1.

(A) Effect of doxycycline and minocycline on OA-NOS expression in human OA-affected cartilage. OA-affected knee articular cartilage from one OA-affected patient was placed in organ culture in 2 ml of medium in the presence or absence (control) of doxycycline and minocycline at 5–80 μg/ml. The spontaneous release of nitrite was monitored at different time intervals. Data are expressed as micromolar nitrite released (mean ± SD, n = 3–4). Zero time indicates spontaneous release of NO at 24, 48, and 72 h, which was 4.8 ± 0.38, 16.4 ± 0.7, and 17.8 ± 0.9, respectively. Statistics were derived using unpaired Student’s t test. Data represent one of three identical experiments with samples from different patients. (B) Effect of doxycycline and minocycline on nitrite accumulation in RAW 264.7 cells stimulated with LPS. Murine macrophage cells (RAW 264.7) were incubated with doxycycline or minocycline (5–80 μg/ml) for 1–2 h followed by addition of LPS at 100 ng/ml. After 14–20 h of incubation, the medium was used to estimate nitrite accumulation by the modified Griess reaction (23). Data are expressed as micromolar of nitrite accumulated at a given time interval (n = 3). Statistics were derived using unpaired Student’s t test. Data represent one of three similar experiments. Graphs were plotted using the delta graph curve-fitting program: polynomial of degree 3.