Discovery of bauxite-type helium source rock in Jinzhong basin, central North China and its resource potential evaluation

1. Objective Among globally known industrial helium-enriched natural gas reservoirs, associated helium is dominantly crust-derived helium(4He), which is generated by the radioactive decay of uranium(U) and thorium(Th) in crustal rocks. These rocks with old ages are also defined as helium source rocks.Published accumulation models for helium have revealed that granite is the main and effective helium source rock in the crust(Li YH et al., 2018).

Neuroprotective effect of ischemic postconditioning on sciatic nerve transection

Ischemic preconditioning or postconditioning has been shown to have neuroprotective effect on cerebral ischemia, but it has not been studied in peripheral nerve injury. In this study, a rat model of sciatic nerve transection was established, and subjected to three cycles of ischemia for 10 minutes ＋ reperfusion for 10 minutes, once a day. After ischemic postconditioning, serum insulin-like growth factor 1 expression increased; sciatic nerve Schwann cell myelination increased; sensory function and motor function were restored. These findings indicate that ischemic postconditioning can effectively protect injured sciatic nerve. The protective effect is possibly associated with upregulation of insulin-like growth factor 1.

Functional Outcome of Pronation-External Rotation-Weber C Ankle Fractures with Supracollicular Medial Malleolar Fracture Treated with or without Syndesmotic Screws： A Retrospective Comparative Cohort Study

Background： In treatment of ankle fracture, intraoperative stress tests are used to assess the syndesmotic injury and instability. However, the optimized timing of the strees test should be applied whether in pre- or post-bony fixation during operation is seldom be reported in previous studies. The different strategies on stress test timing would exhibit opposite results within a type ofpronation-external rotation （PER） fractures with supracollicular medial malleolar （SMM） fractures. This study was designed to assess the 3-year ffmctional outcomes of the special PER fractures with or without a syndesmotic transfixation based on the results of two different intraoperative stress test strategies. Methods： This retrospective cohort study included 61 PER injury-Weber C ankle fractures combined with SMM fractures who were treated in Beijing Jishuitan Hospital between 2013 and 2014 and followed up for 3 years. Stress test was performed twice intraoperatively. A positive intraoperative stress test before bony fixation and a negative intraoperative stress test after bony fixation were found in these included patients. Twenty-nine patients （Group 1 ） were treated without a supplemental syndesmotie screw fixation, according to the negative intraoperative stress test alter bony fixation, while 32 patients （Group 2） were treated with an additional syndesmotic screw fixation based on the positive intraoperative stress test before bony fixation. The American Orthopaedic Foot and Ankle Society （AOFAS）Ankle-Hindfoot Scale and Visual Analog Scale （VAS） for pain scores were the main measurements of outcome. The statistical index of demographic data, fracture morphologic data, time interval of follow-up, AOFAS and VAS were recorded and assessed by SPSS 21.0 software through Fisher exact tests and oneway analysis of variance. The associations between the main outcomes and influential factors were evaluated by linear regression models. Results： We observed no difference in the distribution of age, sex, presence of associated posterior malleolus （PM）, fracture dislocation, and fixation of associated PM between two treatment groups. With the numbers available, no statistically significant association could be detected with regard to the AOFAS （Group 1 vs. Group 2, 96.72 ± 6.20 vs. 94.63 ± 8.26, F = 1.24, P = 0.27） and VAS （Group I vs. Group 2, 1.47 ± 2.14 vs. 0.72 ± 1.49, F = 2.44, P - 0.12） in association with two strategies. Conclusions： The present study indicates no difference to the use of the syndesmotic screw in terms of the ffinctional outcome between syndesmosis transfixation and no-fixation patients among PER-Weber C ankle fi＇acture patients with SMM fracture after 3-year ibllow-up. More attention should be paid to pre- and post-bony-fixation intraoperative stress tests and the morphology of medial malleoli fractures in ankle fractures.

Biomechanical Study of the Fixation Strength of Anteromedial Plating for Humeral Shaft Fractures

Background： Open reduction and internal fixation with plate and screws are the gold standard for the surgical treatment of humeral shaft fractures, this study was to compare the mechanical properties ofanteromedial, anterolateral, and posterior plating for humeral shaft fractures. Methods： A distal third humeral shaft fracture model was constructed using fourth-generation sawbones （#3404, composite bone）. A total of 24 sawbones with a distal third humeral shaft fracture was randomly divided into three Groups： A, B, and C （n = 8 in each group） for anteromedial, anterolateral, and posterior plating, respectively. All sawbones were subjected to horizontal torsional fatigue tests, horizontal torsional and axial compressive fatigue tests, four-point bending fatigue tests in anteroposterior （AP） and mediolateral （ML） directions and horizontal torsional destructive tests. Results： In the horizontal torsional fatigue tests, the mean torsional angle amplitude in Groups A, B, and C were 6.12°, 6.53°, and 6.81°. In horizontal torsional and axial compressive fatigue tests, the mean torsional angle amplitude in Groups A, B, and C were 5.66°, 5.67°, and 6.36°. The mean plate displacement amplitude was 0.05 mm, 0.08 mm, and 0.10 mm. Group A was smaller than Group C （P 〈 0.05）. In AP four-point bending fatigue tests, the mean plate displacement amplitude was 0.16 ram, 0.13 ram, and 0.20 mm. Group B was smaller than Group C （P 〈 0.05）. In ML lbur-point bending fatigue tests, the mean plate displacement amplitude were 0.16 mm, 0.19 ram, and 0.17 ram. In horizontal torsional destructive tests, the mean torsional rigidity in Groups A, B, and C was 0.82, 0.75, and 0.76 N·m/deg. The yielding torsional angle was 24.50°, 25.70°, and 23.86°. The mean yielding torque was 18.46, 18.05. and 16.83 N·m, respectively. Conclusions： Anteromedial plating was superior to anterolateral or posterior plating in all mechanical tests except in AP four-point bending fatigue tests compared to the anterolateral plating group. We can suggest that anteromedial plating is a clinically safe and effective way for humeral shaft fractures.

Application of Continuous Proximal Sciatic Nerve Blockade in the Treatment of Flexion Contractures After Primary Total Knee Arthroplasty

The main objective of total knee arthroplasty （TKA） is to relieve pain and restore normal knee function while providing stability through the gait cycle. However, postoperative flexion contracture can lead to suboptimal overall results.

Macroscopic and Histological Evaluations of Meniscal AIIograft Transplantation Using Gamma Irradiated Meniscus： A Comparative in Vivo Animal Study

Background：Many studies suggest that the gamma irradiation decreases allograft strength in a dose-dependent manner.However,no study has demonstrated that this decrease in strength translates into higher failure rate in meniscal allograft transplantation （MAT）.The aim of this study was to investigate the effects of gamma irradiation on macroscopic and histological alterations of transplanted meniscal tissue and joint cartilage after MAT.Methods：Medial total meniscectomies were performed on the right knees of 60 New Zealand white rabbits.All meniscal allografts were divided into three groups （20 in each group） and then sterilized with 0 Mrad,1.5 Mrad,or 2.5 Mrad of gamma irradiation.For each group,5 menisci were randomly chosen for scanning electron microscopic （SEM） analysis and the remaining 15 were prepared for MAT surgeries.Forty-five right knees received MAT surgeries （0 Mrad group,1.5 Mrad group,2.5 Mrad group,15 in each group）,whereas the remaining 15 only received medial meniscectomy （Meni group）.The left knees of the Meni group were chosen as the Sham group （n =15）.All the rabbits were sacrificed at week 24 postoperatively.Cartilage of the medial compartment of each group was evaluated macroscopically using the International Cartilage Repair Society （ICRS） score and then histologically using the Mankin score based on the Masson Trichrome staining.Results：The SEM analysis confirmed that the meniscal collagen fibers would be significantly damaged as the dose of gamma irradiation increased.At week 24,the overall scores of macroscopic evaluations of the transplanted meniscal tissue showed no significant differences among the three groups receiving MAT surgeries,except for 2 in the 2.5 Mrad group presented partial radial tears at midbody.The ICRS scores and the Mankin scores showed the lowest in the Sham group and the highest in the Meni group （P 〈 0.05）.For the three groups receiving MAT surgeries,the 2.5 Mrad group showed significant higher ICRS scores and Mankin scores than both the 0 Mrad group and the 1.5 Mrad group （P 〈 0.05）.Whereas the 1.5 Mrad group presented similar results to the 0 Mrad group concerning both the ICRS scores and the Mankin scores.Conclusions：The current in vivo animal study proved that although the meniscal collagen fibers were damaged after gamma irradiation,the failure rate of MAT surgeries might not significantly increase if the irradiation dose was 〈1.5 Mrad for New Zealand white rabbits.