The increased use of allograft tissue in the reconstruction of anterior cruciate ligament has brought more focus to the effect of storage and treatment on allograft. The purpose of this study was to observe the effect of histology and biomechanics on Achilles tendon in rabbits through repeated freezing-thawing before allograft tendon transplantation. Rabbit Achilles tendons were harvested and processed according to the manufacture's protocol of tissue bank, and freezing-thawing was repeated three times (group 1) and ten times (group 2). Those received only one cycle were used as controls. Then, tendons in each group were selected randomly to make for histological observations and biomechanics test. Histological observation showed that the following changes happened as the number of freezing-thawing increased: the arrangement of tendon bundles and collagen fibrils became disordered until ruptured, cells disrupted and apparent gaps appeared between tendon bundle because the formation of ice crystals. There were significant differences between the experimental and control groups in the values of maximum load, energy of maximum load and maximum stress, whereas no significant differences existed in other values such as stiffness, maximum strain, elastic modulus, and energy density. Therefore, repeated freezing-thawing had histological and biomechanical effect on Achilles tendon in rabbits before allograft tendon transplantation. This indicates that cautions should be taken in the repeated freezing-thawing preparation of allograft tendons in clinical application.

Aim:The aim of this study is to explore the function of miR-20a in osteosarcoma. Materials & methods: miR-20a expression was measured by real-time PCR. miR-20a mimics, inhibitor and scramble siRNA were transfected into osteosarcoma cells to observe effects on colony formation and tumor growth. Moreover, relationships of miR-20a with TAK1 were investigated by western blot and luciferase activity. Results: We found that miR-20a was downregulated in osteosarcoma, and overexpression of miR-20a reduced colony formation and tumor growth. Furthermore, the data revealed that the function of miR-20a was probably exerted via targeting the TAK1 expression. Overexpression of miR-20a sensitizes the osteosarcoma cells to chemotherapeutic drugs. Conclusion: Our data identify the role of miR-20a in osteosarcoma growth, indicating its potential application in chemotherapy. Osteosarcoma is the most common primary malignant bone tumor with high morbidity in young adults and children, comprising 2.4% of all malignancies in pediatric patients and about 20% of all primary bone tumors [1]. It occurs mainly around regions with active bone growth and reparation. Osteosarcoma is highly aggressive and responded poorly to chemotherapy, and the 5-year survival rate for patients with metastatic osteosarcoma is only 14% [2]. Therefore, it is of extreme significance to elucidate novel molecular targets to develop alternative therapeutic target for this disease.miRNAs are a small family of noncoding RNAs that play important roles in the development of human diseases by negatively regulating gene expression at either post-transcriptional or translational levels [3,4]. Over the last decade, many miRNAs have been showed in regulating diverse biological events such as cell proliferation, differentiation and apoptotic processes [5][6][7], which are important in the development of cancer. Accumulated evidence indicated that aberrant expression of miRNAs associates with various types of cancer. These dysregulated miRNAs function as either oncogenes or tumor suppressors in carcinogenesis and progression of cancers [8,9]. Thus, to explore the aberrant miRNAs expression in osteosarcoma might lead to the discovery of novel miRNAs biomarkers.In this study, we found that miR-20a was downregulated in osteosarcoma samples and osteosarcoma cell lines, and the ectopic expression of miR-20a reduced cell colony formation in vitro and tumor growth in vivo. Furthermore, bioinformatic prediction and experimental validation revealed that the function of miR-20a was probably exerted via targeting the TAK1 expression. To translate these findings, overexpression of miR-20a sensitizes the osteosarcoma cells to chemotherapeutic drugs. Collectively, our data identify the key role of miR-20a in osteosarcoma growth, indicating its potential application in cancer chemotherapy.

Abstract. Osteosarcoma is the most common aggressive sarcoma of the bone in children and adolescents. It is characterized by a high level of genetic instability and recurrent DNA deletions and amplifications. microRNAs (miRNAs) play a key role in cancer initiation, progression and metastasis; however, the potential role of miRNAs in osteosarcoma remains largely unknown. In the present study, miR-433 was shown to be overexpressed in osteosarcoma tissues compared with normal human osteoblasts. Transfection of miR-433 mimics into osteosarcoma cell lines significantly decreased apoptosis by targeting programmed cell death 4, a tumor suppressor that is involved in apoptosis. In contrast, inhibition of miR-433 enhanced apoptosis. Furthermore, in vivo miR-433 overexpression inhibited the apoptosis of tumor cells and increased tumor growth. The results of the present study suggested that miR-433 is a potential molecular target for osteosarcoma therapy.

Nearly all previous studies in posterior tibial slope (PTS) and anterior cruciate ligament (ACL) injuries ignored age-related changes, and the published data are inconsistent. The objective of this study was to reveal age-related changes of PTS and its roles in ACL injury. Data for 2618 lower limbs were included initially based on the availability of lateral X-rays and a suitable femorotibial angle. The final 1431 subjects were analyzed according to age, sex, side, and injury status. Student t-tests, 1-way analysis of variance, and curve fitting were used to analyze data. The PTS in males was greater than that in females in the 0-9 and 30-39-year-old groups, but this pattern was reversed in the 40-49, 60-69, 70-79, and 80-89-year-old groups. The PTS was greater on the left side than on the right side in the 0-9, 10-19, 50-59, 60-69, and 80-89-year-old groups. The curve fitting for PTS demonstrated a trend of first decreasing and then increasing with aging. The PTS values differed significantly between knees with an ACL injury and those without in the 20-29, 30-39, and 40-49-year-old groups but not in the 50-59-year-old group. The PTS follows a trend of first decreasing and then increasing, and its role in ACL injury changes with advancing age. The higher PTS is only unrelated to the risk of ACL injury in age groups with a lower mean PTS value.Key words: Age-related -Posterior tibial slope -Anterior cruciate ligament -Injury -X-ray T he posterior inclination of the tibial plateau relative to the longitudinal axis of the bone, known as the posterior tibial slope (PTS), is important to know for the pathology of anterior cruciate ligament (ACL) injury.1 On the basis of large X-rays of the lower limbs of adults, Genin et al 1 reported that the PTS ranges from 08 to 188. Jiang et al 2 found that the PTS, as determined from lateral radiography of the knee, is 108 6 48 (range, 08 to 208). Chiu et al 3 studied 25 pairs of Chinese cadaveric tibias and concluded that the medial PTS is 14.88, the lateral PTS is 11.88, the PTS according to intramedullary radiographic measurement is 11.58, and the PTS based on extramedullary radiographic measurement is 14.78. Moreover, many studies have reported that an increased PTS is a risk factor for ACL injury. Brandon et al 4 found that an increased PTS is associated with noncontact ACL rupture in both males and females. Todd et al 5 and Hohmann et al 6 reported that an increased PTS is a possible risk factor for noncontact ACL injury only among women. Senis ik et al 7 found that there is a higher PTS in injured male soccer players compared with uninjured male players. Webb et al 8 suggested that an increased PTS is associated with a greater chance for further ACL injury after ACL reconstruction. Recently, Li et al 9 reported that a PTS of 58 or greater is a new risk factor for ACL reconstruction failure. However, some other studies refuted the conclusions above. Meister et al 10 found that the PTS is not an identifiable risk factor for noncontact ACL injury on the basis of 100 knee jo...