External apical root resorption(EARR)is one of the most common side effects of orthodontic treatment.Contact with sur-rounding anatomical structures during tooth movement is a significant cause for EARR.However,a comprehensive review of factors leading to EARR due to direct contact of surrounding anatomical structures with the root apex during orthodontic treatment is still lac-king.This review summarizes the anatomical structures related to EARR,including alveolar bone,incisive canal,maxillary sinus,ad-jacent teeth,and bone islands.Alveolar bone,incisive canal,and adjacent teeth can directly cause EARR during orthodontic treat-ment,while the impact of the maxillary sinus and bone islands on EARR has not been discovered so far.Analyzing the anatomical structures around the tooth roots can help develop more effective methods to prevent or reduce the occurrence of EARR during orthodon-tic treatment.

External apical root resorption(EARR)is one of the most common side effects of orthodontic treatment.Contact with sur-rounding anatomical structures during tooth movement is a significant cause for EARR.However,a comprehensive review of factors leading to EARR due to direct contact of surrounding anatomical structures with the root apex during orthodontic treatment is still lac-king.This review summarizes the anatomical structures related to EARR,including alveolar bone,incisive canal,maxillary sinus,ad-jacent teeth,and bone islands.Alveolar bone,incisive canal,and adjacent teeth can directly cause EARR during orthodontic treat-ment,while the impact of the maxillary sinus and bone islands on EARR has not been discovered so far.Analyzing the anatomical structures around the tooth roots can help develop more effective methods to prevent or reduce the occurrence of EARR during orthodon-tic treatment.

c-Met is one member of the receptor tyrosine kinases (RTKs).It is closely related between the over-expression of c-Met and a wide variety of tumor occurrence, development, invasion, metastasis, prognosis and drug resistance.Therefore, c-Met is a potential target for oncotherapy, and researches on its inhibitors have become a hot spot in the field of tumor treatment.Aptamers targeting c-Met are gained from systematic evolution of ligands by exponential enrichment (SELEX).They can bind to c-Met with high specificity and affinity, resulting in the activation or inhibition of c-Met.We envision that anti-c-Met aptamers would be ideal new c-Met inhibitors after optimization, and could be developed into potential targeted drugs for cancers.

The heptadecapeptide orphanin FQ(OFQ)is a recently discovered neuropeptide that exhibits structural features reminiscent of the opioid peptides and that is an endogenous ligant to a G protein-coupled receptor sequentially related to the opioid receptors.OFQ was originally isolated from brain,but the presence of OFQ in peripheral tissues,especially in cardiovascular system,has not been clarified.The present study was designed to investigate the peripheral tissue distribution of OFQ precusor Mrna in stroke-prone spontaneously hypertensive rats(SHRSP)and compare the difference of OFQ precusor Mrna expression in aorta or cultured vascular smooth muscle cells(VSMCs)between SHRSP and wistar-Kyoto normotensive(WKY)rats.By using quantitative reverse transcription-polymerase chain reaction(RT-PCR),OFQ precusor Mrna was detected in aorta and ovary at high levels comparable with the amounts found in brain.Moderate expression was found in testis,while a little OFQ precusor Mrna could be detected in atrium.All other peripheral tissues examined from SHRSP,including ventricle,liver,lung and kidney,showed no expression of OFQ precusor Mrna.In the vascular system,OFQ precusor Mrna was expressed in aorta,pulmonary artery,renal artery and vein at high levels comparable with the amounts found in brain.We also found that OFQ precusor Mrna levels were much higher in aorta or cultured VSMCs from SHRSP than those from WKY rats.In conclusion,the present study has shown that OFQ precusor Mrna is present in some peripheral tissues,especially in cardiovascular and reproductive system,suggesting that OFQ possibly involves in the regulation of cardiovascular and reproductive functions.