Figure 2.

Serum RANKL and RANKL mRNA in cancellous bone from the proximal femur in men and women. (a, d) Fasting blood was taken at the time of operation for total hip replacement and serum total receptor activator of nuclear factor-κB ligand (RANKL) levels were determined, using ELISA, and plotted as a function of age. For the males (panel a), regression analysis indicated a negative correlation between these parameters (r = -0.52, P = 0.057; after removal of the outlier value: r = -0.67, P = 0.012). (b, e) Cancellous bone from the proximal femur was obtained at the time of operation for total hip replacement and extracted for RNA. RANKL mRNA levels, normalized against glyceraldehyde phosphate dehydrogenase (GAPDH) mRNA levels, were determined using real-time RT-PCR and are plotted as a function of age. For the men (panel b), regression analysis indicated a positive correlation between these parameters (r = 0.73, P = 0.003). (c, f) Serum total RANKL levels plotted against normalized RANKL mRNA levels. For the males (panel c), regression analysis indicated a negative correlation between these parameters (r = -0.70, P = 0.007). For the females (panels d, e and f), no correlations were found between any of these parameters.