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Joint contracture is increasingly regarded as a clinical problem that leads to irreversible dysfunction of the joint. It is a pathophysiological process following joint injury, which is marked by the activation of myofibroblasts. There is currently no effective treatment for the prevention of joint contracture. Curcumin is a polyphenol pigment extracted from turmeric, which possesses anti-inflammatory, antioxidative, and antitumor properties. In the present study, we demonstrated that curcumin exerts a protective effect against joint contracture via the inhibition of myofibroblast proliferation and migration in a time- and concentration-dependent manner. Moreover, we indicated that phosphatase and tension homolog (PTEN) was downregulated in myofibroblasts in vitro and in the contracture capsule tissues of patients in vivo. Additionally, western blot analysis revealed a negative correlation between the expression levels of PTEN and the fibrosis marker protein alpha smooth muscle cell actin. Methylation-specific PCR results suggested that curcumin was able to demethylate PTEN in a similar manner to the demethylation agent 5-azacytidine, increasing PTEN expression and further inhibiting phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling. In conclusion, our data illustrate part of the mechanism of curcumin inhibition in joint contracture. These results support the hypothesis that curcumin may potentially be used as a novel candidate for the treatment of joint contracture.

The present study compared the patterns of brain activation elicited by two-digit addition and subtraction problems. Thirty-two Chinese undergraduates of the same educational background and of similar age were asked to assess whether arithmetic operations were true or false during functional magnetic resonance imaging. Results showed that both complex addition and subtraction were supported by the broad neural system that involved regions within the inferior parietal lobule, the precuneus, and the inferior occipital gyrus, as well as some subcortical structures. Nevertheless, complex problems involving addition elicited more activation mainly in the bilateral medial frontal gyrus, whereas problems involving subtraction had more activation in the precentral gyrus and the thalamus in the right hemisphere, as well as the inferior parietal lobule in the left hemisphere. This pattern of dissociated activation suggests that partially separate neuronal networks might support these different operations. It also suggests that complex addition has a greater reliance on the fronto-parietal cortical circuit and subtraction on the parieto-subcortical circuit.