Biodegradable Polymers In article 2300068 by Qiang Chen, Yulin Li, and co-workers, a versatile disorder-to-order technology (VDOT) is proposed to fabricate a stereo-composite self-reinforced polymer fiber by mimicking the superstructure of nature bones at the nanoscale. The VDOT-based polymer fiber shows an oriented shish-kebab structure, excellent mechanical performance, and biodegradation stability, which overcome the mechanical inferiority of the current biomedical polymers and extend their applications.
Objective To study the vascular architecture and the indication of endovascular embolization of intramedullary AVMs and evaluate the therapeutic effect. Methods 15 patients (male 9 and female 6 , 9 to 43 years old) with acute or progressive paralysis were undergone DSA and endovascular embolization. The embolic material was PVA particles and silk suture segments. Lidocaine test was performed before embolization if it was necessary. Results There were 3 glomus AVMs and 12 juvenile AVMs among the 15 cases. The glomus AVM was usually fed by single artery, the juvenile AVM was fed by two or more arteries. Among 15 patients, 2 were cured, 3 had excellent effect, 6 had good effect, 4 showed no changed and no one became worsening. After 6 months to 5 years follow up, 7 patients with recurrency were re embolized,another 2 patients were lost of follow up. Conclusions Endovascular embolization is a mild invasive, safety and effective therapeutic method for curing AVMs by avascularizing the rudus and decreasing the drainage vein pressure and bleeding.
To explore the changes of magnetic resonance imaging (MRI) and computed tomography (CT) after transplantation of VX2 carcinoma into lumbar vertebrae of rabbits under CT guidance and examine its relationship with the onset of paralysis.A total of 52 rabbits were randomly divided into 4 groups. Under CT guidance, pieces of VX2 carcinoma were transplanted into the first or second lumbar vertebra in Groups A, B and C (n = 14 each) while sham operation was performed in Group D (n = 10). The anticipated endpoints of group A was natural death or Day 50 post-operation, group B Day 3 after onset of paralysis, group C Day 14 post-transplantation and group D natural death or Day 50 post-operation. CT and MR scans were performed at an interval of 7 days and hind limb functions monitored daily post-operation until endpoints. Pathohistological examinations of vertebrae were performed at endpoints.All lumbar vertebrae were successfully transplanted under CT guidance. Thirty-two rabbits with spinal tumor and 9 surviving rabbits in the control group were monitored until endpoints. Abnormal signals on target vertebrae appeared on MRI in all 41 rabbits at Day 7 post-operation while positive CT findings were absent. No abnormal MRI/CT findings were found in 9 control rabbits from Day 14 post-operation to the end of study. Significant differences (P < 0.001) existed between the rates of tumor visualization with 65.6% (21/32) on MR and 3.1% (1/32) on CT at Day 14, 100% (21/21) on MR and 42.9% (9/21) on CT at Day 21. The rates of tumor visualization were 100% on both MR and CT from Day 28 to endpoints. The average survival time of Group A was significantly shorter than Group D (40 ± 4 vs 50 days, P < 0.01). The onset time of paralysis time in Group A (22 ± 5 days) had no significant difference with Group B (22 ± 5 days) (P = 0.952).A rabbit model of spinal metastasis is established with high rates of success and reproducibility. Vertebral tumor may be located earlier on MR than CT after transplantation of VX2 carcinoma. The examinations of MRI and CT after Day 7 post-operation are controversial. The survival time of rabbits with paralysis caused by spinal tumor is significantly shortened.
Nitrogen (N) deposition can affect the global ecosystem carbon balance. However, how plant community assembly regulates the ecosystem carbon exchange in response to the N deposition remains largely unclear, especially in alpine meadows. In this study, we conducted a manipulative experiment to examine the impacts of N (ammonium nitrate) addition on ecosystem carbon dioxide (CO2) exchange by changing the plant community assembly and soil properties at an alpine meadow site on the Qinghai-Tibetan Plateau from 2014 to 2018. The N-addition treatments were N0, N7, N20, and N40 (0, 7, 20, and 40 kg N ha-1year-1) during the plant growing season. The net ecosystem CO2 exchange (NEE), gross ecosystem productivity (GEP), and ecosystem respiration (ER) were measured by a static chamber method. Our results showed that the growing-season NEE, ER and GEP increased gradually over time with increasing N-addition rates. On average, the NEE increased significantly by 55.6 and 65.2% in N20 and N40, respectively (p < 0.05). Nitrogen addition also increased forage grass biomass (GB, including sedge and Gramineae) by 74.3 and 122.9% and forb biomass (FB) by 73.4 and 51.4% in N20 and N40, respectively (p < 0.05). There were positive correlations between CO2 fluxes (NEE and GEP) and GB (p < 0.01), and the ER was positively correlated with functional group biomass (GB and FB) and soil available N content (NO3--N and NH4+-N) (p < 0.01). The N-induced shift in the plant community assembly was primarily responsible for the increase in NEE. The increase in GB mainly contributed to the N stimulation of NEE, and FB and the soil available N content had positive effects on ER in response to N addition. Our results highlight that the plant community assembly is critical in regulating the ecosystem carbon exchange response to the N deposition in alpine ecosystems.
Biodegradable polymer as traditional material has been widely used in the medical and tissue engineering fields, but there is a great limitation as to its inferior mechanical performance for repairing load-bearing tissues. Thus, it is highly desirable to develop a novel technology to fabricate high-performance biodegradable polymers. Herein, inspired by the bone's superstructure, a versatile disorder-to-order technology (VDOT) is proposed to manufacture a high-strength and high-elastic modulus stereo-composite self-reinforced polymer fiber. The mean tensile strength (336.1 MPa) and elastic modulus (4.1 GPa) of the self-reinforced polylactic acid (PLA) fiber are 5.2 and 2.1 times their counterparts of the traditional PLA fiber prepared by the existing spinning method. Moreover, the polymer fibers have the best ability of strength retention during degradation. Interestingly, the fiber tensile strength is even higher than those of bone (200 MPa) and some medical metals (e.g., Al and Mg). Based on all-polymeric raw materials, the VDOT endows bioinspired polymers with improved strength, elastic modulus, and degradation-controlled mechanical maintenance, making it a versatile update technology for the massive industrial production of high-performance biomedical polymers.
A retrospective study was performed in patients with a repeat percutaneous vertebroplasty (PV) at the vertebral levels previously undergoing vertebroplasty.Our purpose of this study is to examine if a repeat PV is effective on pain-relief at the vertebral levels previously undergoing vertebroplasty.Although pain-relief is usually high with the treatment of PV in the painful osteoporotic vertebral compression fractures, there are still about 5% to 22% of such patients experiencing no improvement on pain after PV. A repeat PV at the same vertebrae previously treated with PV may be an option for these patients without a pain-relief.Out of 334 procedures of PV in 242 patients with osteoporotic vertebral compression fractures from October 2000 to June 2006 in our institute, 15 vertebrae in 15 patients with unrelieved pain in 4 to 32 days after an initial PV were treated with a repeat vertebroplasty. The clinical outcomes were assessed by measurements of visual analog scale, and the imaging features were analyzed pre- and postprocedure.The mean volume of Polymethylmethacrylate injected in each vertebra was 4.0 mL (range, 1.5-9 mL) in the repeat PV. During the first month of follow-up after repeat PV in this series, a mean visual analog scale scores of the pain level was reduced from 8.6 (range, 7-10) preprocedure to 1.67 points (range, 0-4) postprocedure, with a mean reduction of 6.93 points (range, 4-8). Complete and partial pain relief were reached in 11 (73%) and 4 patients (27%), respectively in a mean follow-up of 15 months. No serious complications related to the procedures occurred, but asymptomatic Polymethylmethacrylate leakage around vertebrae was demonstrated on radiograph or computed tomography in 2 patients.The outcomes of this series suggest that repeat PV is effective at the same vertebral levels in patients without pain-relief who underwent previous PV. Absent or inadequate filling of cement in the unstable fractured areas of the vertebral body may be responsible for the unrelieved pain after the initial PV.
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