Objective To study the mechanism of steroid induced necrosis of femoral head. Methods The cell experiment of effect of dexamethasone on the osteoblast in vitro and animal experiment of steroid induced necrosis of femoral head. Results The cell experiment showed that dexamethasone played two roles to bone marrow' mononucleate cells in vitro. The first was that it can prevent the cells from differentiating into the osteoblasts and the second was that it can cause fatty degeneration. The animal experiment showed the number of vacant bony lacunae in femoral head, the average diameter of fat cells in marrow cavity were increased and the number of blood vessles in subchondral areas was decreased with large doses of dexamethasone. Conclusions The mechanism of steroid induced necrosis of femoral head was that dexamethasone can inhibit the grouth of the osteoblasts directely, and cause fatty proliferation of bone marrow resulting in disorder of micro circulation and osteonecrosis in the femoral head.

Objective To evaluate the clinical value of acetic acid with narrow-band imaging ( NBI ) and magnifying endoscopy ( ME ) on diagnosis of small colorectal polyps. Methods In this prospective study, 261 small colorectal polyps from 122 patients were observed by ME, NBI-ME, and acetic acid with NBI-ME, and then received endoscopic treatment. Endoscopic images were stored electronically and randomly allocated to 3 experts and 3 non-experts for diagnosis using Kudo pit pattern. The postoperative pathologic results acted as gold standard to evaluate the diagnostic accuracy of different endoscopic modes for small colorectal polyps. The image definition and interobserver agreement were compared among different endoscopic modes. Results The diagnostic accuracy of ME, NBI-ME, and acetic acid with NBI-ME for small colorectal polyps was 65. 5％ ( 171/261) , 90. 0％ ( 235/261) , and 94. 6％ ( 247/261) , respectively, in the experts group, and 57. 1％ ( 149/261) , 83. 1％ ( 217/261) , and 89. 3％ ( 233/261) , respectively, in the non-experts group. All experts and non-experts diagnosed small colorectal polyps more accurately by acetic acid with NBI-ME than by NBI-ME ( all P<0. 05 ) and ME ( all P<0. 001 ) . The image definition scores of acetic acid with NBI-ME in the experts group and non-experts group were significantly higher than those of NBI-ME and ME ( all P<0. 001) . The results of interobserver agreement showed that Kappa values (95％CI) of ME, NBI-ME, and acetic acid with NBI-ME diagnosis were 0. 578 (0. 508-0. 648), 0. 669 (0. 599-0. 739), and 0. 940 (0. 870-1. 010), respectively, for experts and 0. 476 (0. 406-0. 546), 0. 534 ( 0. 464-0. 604) , and 0. 830 ( 0. 760-0. 900 ) , respectively, for non-experts. Acetic acid with NBI-ME showed good interobserver agreement. Conclusion Acetic acid with NBI-ME has a higher diagnostic accuracy and good reproducibility for colorectal small polyps compared with ME and NBI-ME.

End-stage liver disease (ESLD) includes decompensated liver cirrhosis and liver failure, which usually have dangerous conditions and a poor prognosis. Liver transplantation is the only effective therapy for ESLD, but its clinical application is limited due to shortage of liver donors, immunological rejection, and expensive costs. Mesenchymal stem cells (MSCs) can differentiate into hepatocyte-like cells and alleviate liver fibrosis by regulating immune function through paracrine, and therefore, MSCs have a wide application prospect in the field of ESLD treatment. A number of clinical studies have shown that MSC infusion is safe and effective in the treatment of ESLD during a short period of time, and there is also certain clinical evidence for its long-term safety and efficacy. MSC-derived exosomes (MSC-Exo) do not have a complete cellular structure and can promote hepatocyte regeneration through a variety of mechanisms, and their clinical value has attracted more and more attention, but there are few studies on this issue. Currently, the core mechanism of MSC therapy for ESLD and the standardized process of MSC preparation are the problems needing to be solved urgently.