Transcription Factor SP2 Regulates Ski-mediated Astrocyte Proliferation In Vitro.

Transcription factors bind specific sequences upstream of the 5' end of their target genes to ensure proper spatiotemporal expression of the target gene. This study aims to demonstrate that the transcription factor SP2 regulates expression of the Ski gene, which has specific binding sites for SP2, and thus enables Ski to regulate astrocyte proliferation. The upstream regulation mechanism of astrocyte proliferation was explored to further regulate the formation of glial scar in specific time and space after spinal cord injury. JASPAR and UCSC databases were used to predict transcription factor binding and the threshold was gradually reduced to screen transcription factors upstream of Ski, leading to the identification of SP2. Next, we analyzed the correlation between the expression of SP2 and Ski in normal astrocytes and reactive astrocytes, as well as the changes in astrocyte proliferation. To confirm that SP2 regulates Ski during astrocyte proliferation, astrocytes were transfected siRNA targeting SP2 and then astrocyte proliferation were analyzed. Finally, a dual luciferase reporter assay and Chromatin immunoprecipitation (ChIP) assay confirmed that the promoter region of Ski contained a specific SP2 binding site. This is the first that SP2 has been identified and confirmed to play an important role in astrocyte proliferation by regulating Ski expression. These results may help identify novel targets for the treatment of spinal cord injury.

[Surgical treatment strategy for flatfoot related with accessory navicular].

Accessory navicular source flatfoot is one of the foot deformity of clinical common disease,its treatment method is more controversial, differences in clinical efficacy of different surgical methods, according to accessory navicular source flatfoot symptoms of surgical treatment,there is no uniform standard, around a pair of accessory navicular excision how to reconstruct the arch produced a series of operation methods, the clinical curative effect of different operative methods produce also different, how to develop the operation strategy, choose operation method, and after acessory navicular excision whether to rebuild posterior tibial tendon, how to rebuild, the problems such as how to rebuild is the research hotspot and difficulty, looking forward to further research.

[Percutaneous achilles tendon lengthening through double hemisection in the treatment of achilles contracture syndrome].

OBJECTIVE: To explore the surgical approach of percutaneous double hemisection and evaluate its clinical efficacies. METHODS: From May 2006 to November 2011, a total of 59 patients were recruited. There were 36 males and 21 females with a mean age of 38.2 years (range: 8 - 62). Forty-two varus and 6 valgus feet underwent percutaneous double hemisection. The 0.5 cm coracoid incision was adopted at the medial and lateral aspects of Achilles tendon. Percutaneous double hemisection was employed according to the deformity angles of varus and valgus feet. Manipulative correction was applied slowly until 30° dorsiflexion of ankle. Short leg cast was immobilized for 5 weeks at 30° dorsiflexion of ankle. The force of Achilles tendon, motion of ankle and Hannover Achilles tendon scores were followed up. RESULTS: Fifty-two patients were followed up for a mean period of 16.5 months (range: 6 - 60). Seven patients were lost. At the end of follow-up, 48 patients with varus and valgus deformities were corrected effectively. When compared with the normal side, the force of Achilles of the operated side of 50 patients had no change while that of 2 patients decreased slightly; the motion of ankle joint increased from (2.8 ± 0.3)° preoperatively to (28.5 ± 1.4)° postoperatively (P < 0.05); the Hannover Achilles Tendon Scores rose from (68.5 ± 3.5) preoperatively to (82.6 ± 4.2) points postoperatively (P < 0.05). The outcomes were excellent (n = 44), very good (n = 5), good (n = 2) and poor (n = 1). The excellent and good rate was 94.2%. CONCLUSION: As an effective therapy for Achilles tendon contracture syndrome, percutaneous double hemisection has fewer complications and a faster recovery.

[Effects of different cyclic mechanical stretching loads on human tenocytic cytoskeleton in vitro].

OBJECTIVE: To investigate the human tenocyte cytoskeleton under different in vitro stretching conditions and analyze the relations between the changes of tenocytic cytoskeleton and different stretching loads. METHODS: Human tenocytes, cultivated for 5 -7 passages, were stretched under 4%, 8% and 12% cyclic mechanical stretching with a duration of 2, 4, 8, 12, 24 hours and a frequency of 0.5 and 1.0 Hz. Laser scanning confocal microscope was used to examine the changes of F-actin and nucleus after immunofluorescent staining at different cyclic mechanical stretching loads on human tenocyte. The uni-cell average fluorescence intensity was measured with an image analysis system by the photos of human tenocyte cytoskeleton and analyzed by the single factor analysis of variance. RESULTS: After cyclic stretching under 4% stretching with a duration of 2 hours at 0.5 Hz, the microfilament of human tenocyte had an irregular and dim alignment. F-actin was thicker and ruptured under 4% stretching with a duration of 4 hours. Under 8% stretching with a duration of 4 hours at 0.5 Hz, all actin microfilaments ruptured, but part of membrane microfilament remained intact. There was a rising trend of actin filament fracturing under 12% stretching with a duration of 2, 4, 8, 12, 24 hours at 1.0 Hz. And all actin filaments fractured at 24 hours. In the control group, the fluorescent intensity of F-actin was at the highest and the filament remained intact. Under the same stretching frequency, the fluorescent intensity of F-actin had a declining trend and significant differences existed under different stretching loads with different durations (P < 0.05). The fluorescent intensity of F-actin increased in all experimental groups, but it was lower than that of the control group with a duration of 8 hours. The expression of F-actin decreased with a longer duration and reached its lowest at 24 hours. The most obvious phenomenon of nuclear condensation and apoptotic body formation was observed under 4% stretching with a duration of 4 hours at 0.5 Hz. CONCLUSION: Different cyclic mechanical stretching may cause the in vitro breakage and depolymerization of human tenocytic F-actin. Such an effect correlates with stretching force and its duration.