Stimulatory Effects of KPR-A148 on Osteoblast Differentiation and Bone Regeneration

BACKGROUND: Xanthine derivatives have been used to treat a variety of medical conditions including respiratory disease and neural degeneration. However, few studies have reported their effects on bone regeneration. Therefore, we investigated the effects of KPR-A148, a synthetic xanthine derivative on osteoblast differentiation in vitro and bone regeneration in vivo. METHODS: The cytotoxicity of KPR-A148 was evaluated using MC3T3-E1 cells by the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltertrazolium bromide assay. The effects of KPR-A148 on osteoblast differentiation were examined by alkaline phosphatase staining, Alizarin red S staining, and real-time PCR of osteoblast differentiation marker genes. To investigate the effects of KPR-A148 on in vivo bone regeneration, a KPR-A148-containing collagen sponge was implanted into a mouse calvarial defect and KPR-A148 was injected twice, weekly. Bone regeneration was evaluated quantitatively by micro-CT and qualitatively by hematoxylin and eosin, as well as Masson's Trichrome staining. RESULTS: KPR-A148 did not show toxicity in the MC3T3-E1 cells and promoted osteoblast differentiation in a concentration-dependent manner. 10 µM of KPR-A148 showed the most significant effect on alkaline phospatase staining and matrix mineralization. KPR-A148 increased the expression of osteoblast marker genes in both the early and late stages of differentiation. In addition, KPR-A148 significantly induced new bone formation in the calvarial defect model. CONCLUSION: These results demonstrate that KPR-A148 strongly induces osteoblast differentiation and new bone formation. Therefore, it could be used as a potential therapeutic agent for regenerating bone following its destruction by disease or trauma.

Impacts of Urbanization on Delay in Transferred Ischemic Stroke Patients

PURPOSE: Inter-hospital transport poses a number of challenging issues, including prolonging the time interval from symptoms to optimal reperfusion therapy after ischemic stroke. It is unclear whether urbanization is associated with outcomes of inter-hospital transfer including length of stay at the referring hospital (D1LOS). METHODS: A prospective stroke registry from 23 Emergency Departments (ED) from 2007 to 2012 over the nation was collected. Ischemic stroke patients who arrived at the first ED within 24 hours of onset (S2D1) were enrolled. Patients were excluded if time intervals or address were incorrect or missing. Main exposure was urbanization level; urban > or =10,000 and rural <10,000 population. Primary outcome was D1LOS. The secondary outcomes were symptoms to door of the first ED (S2D1) and transfer time to the final ED (T2D2). We compared the D1LOS, S2D1, and T2D2 with median and inter-quartile range (IQR) by urbanization level. RESULTS: Of 5,909 patients transferred from other hospitals, 2,289 patients were analyzed; 1,441 (63%) patients in urban areas, 848 (37%) patients in rural areas were included. The D1LOS and S2D1 in urban was longer than those in rural; 100 minutes (IQR 50~208) for urban VS 82.5 minutes (IQR 48~170.5) for rural (p=0.01) and 66 minutes (IQR 30~240) for urban VS 90 minutes (IQR 30~330) for rural (p=0.001). T2D2 in urban was shorter than that in rural; 54 minutes (IQR 36~78), 40 minutes (IQR 25~65) (p< or =0.00), respectively. CONCLUSION: Urban EDs showed longer D1LOS before transferring patients to the hospital for definite care. Strategy for reducing delay due to inter-hospital transport should differ according to urbanization.