Cyclophilin A (CyPA) induces chemotaxis independent of its peptidylprolyl cis-trans isomerase activity: direct binding between CyPA and the ectodomain of CD147.

Cyclophilin A (CyPA) is a ubiquitously distributed peptidylprolyl cis-trans isomerase (PPIase) that possesses diverse biological functions. Extracellular CyPA is a potent chemokine, which can directly induce leukocyte chemotaxis and contribute to the pathogenesis of inflammation-mediated diseases. Although it has been identified that the chemotaxis activity of CyPA is mediated through its cell surface signaling receptor CD147, the role of CyPA PPIase activity in this process is disputable, and the underlying molecular mechanism is still poorly understood. In this study, we present the first evidence that CyPA induces leukocyte chemotaxis through a direct binding with the ectodomain of CD147 (CD147(ECT)), independent of its PPIase activity. Although NMR study indicates that the CD147(ECT) binding site on CyPA overlaps with the PPIase active site, the PPIase inactive mutant CyPA(R55A) exhibits similar CD147(ECT) binding ability and chemotaxis activity to those of CyPA(WT). Furthermore, we have identified three key residues of CyPA involved in CD147(ECT) binding and found that mutations H70A, T107A, and R69A result in similar levels of reduction in CD147(ECT) binding ability and chemotaxis activity for CyPA, without affecting the PPIase activity. Our findings indicate that there exists a novel mechanism for CyPA to regulate cellular signaling processes, shedding new light on its applications in drug development and providing a new targeting site for drug design.

Analysis of the thoracolumbar fracture with ankylosing spondylitis / 中国骨伤

<p><b>OBJECTIVE</b>To review the clinical features of the thoracolumbar fracture with ankylosing spondylitis (AS) in order to avoid delayed or missed diagnosis.</p><p><b>METHODS</b>Five patients of thoracolumbar fracture with AS treated from April 2005 to June 2007 in our department were studied retrospectively, male 4 cases, female 1 case, the age from 26- to 72-years-old with an average of 44.8 years. Analysis including: case history, number of the ankylosed vertebras, characteristic of fracture, active state rheumatism.</p><p><b>RESULTS</b>The patients had the history of AS for average 22.6 years. The mean number of the ankylosed vertebras was 18.2. Of the 5 cases, 1 case encountered traffic accident, 1case was sprained, and 3 cases without trauma were diagnosed as stress fracture. Two cases were trans-vertebra fracture: the fracture line was through T6, T7, or L1 vertebral body respectively; 3 cases were through the disc space: 2 cases were through L1,2 disc space, 1 case was through L2,3. No compression fracture and neurological injury were found. The acute inflammatory index such as ESR and CRP in 4 cases didn't correlate with the degree of pain. The non-steroidal anti-inflammatory drugs (NSAIDs) hadn't significant effectiveness in relieving pain. The patients were diagnosed as 'relapse' of AS in other hospital, and had been misdiagnosed for average 1.51 months.</p><p><b>CONCLUSION</b>1) the fracture is prevalent at the middle or late period of AS when extensive ankylosis has been existed at the thoracolumbar region; 2) the fracture is common at the lower thoracal spine and the upper lumbar spine, and the majority is the stress fracture; 3) the fracture line may be through the vertebral body, but more often through the disc space; 4) it is like an exacerbation of AS and therefore to be missed diagnosis; 5) when the back pain exacerbated suddenly in the middle or late period of AS, the degree of pain not correlating with acute inflammatory index, and the NSAIDs ineffective, the thoracolumbar fracture should be considered.</p>

Studies on the progress of premixed calcium phosphate cements / 中国骨伤

Calcium phosphate cement (CPC) is considered as an important bone repairing materials due to its excellent biocompatibility, osteoconductivity and remodellability, the study about its performance is still a hot topic in the field of bone tissue engineering. Premixed calcium phosphate cements (PCPC) has advantages that can save operatiion time,be convenient to the operation and preservation compared with the traditional way of immediately mixing calcium phosphate cement. PCCP has overcome the shortcomings of uneven and inadequate mixing, and can be arbitrarily remodeled according to the shape of defect, thus researches on PCCP has also become more and more interested

Total hip replacement in the treatment of severe deformity of the hip caused by advanced ankylosing spondylitis / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the clinical results of the total hip replacement in the treatment of severe deformity of the hip joint caused by advanced ankylosing spondylitis.</p><p><b>METHODS</b>Forty-five hips with severely deformities in 33 patients suffered from advanced ankylosing spondylitis treated by total hip replacement were followed-up from 1992 to 2005 in our department. The pain index, deformity angle, range of motion of the joint, changes of weight baring capacity of a single leg, and the postoperative complications were compared and analysed in this study.</p><p><b>RESULTS</b>The pain was complete released in 27 hips after surgery; the average pain index decreased 1 grade. The angle of flexion deformity of hip decreased by 44.17 degrees averagely. The average range of motion of the hip improved 58.4 degrees. Thirty-one operated hips could bare weight itself. Twenty-two hips occurred prosthesis Sinking of the femur head prosthesis occurred in 22 hips. The sciatic nerve was contused in one case because of violent reduction after the installation of prosthesis, and recovered in 8 months.</p><p><b>CONCLUSION</b>The midterm clinical results of total hip replacement in the treatment of severe deformity of hip caused by advanced ankylosing spondylitis is satisfactory.</p>