Coronavirus Disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), a newly emerged coronavirus, and has been pandemic since March 2020 and led to many fatalities. Vaccines represent the most efficient means to control and stop the pandemic of COVID-19. However, currently there is no effective COVID-19 vaccine approved to use worldwide except for two human adenovirus vector vaccines, three inactivated vaccines, and one peptide vaccine for early or limited use in China and Russia. Safe and effective vaccines against COVID-19 are in urgent need. Researchers around the world are developing 213 COVID-19 candidate vaccines, among which 44 are in human trials. In this review, we summarize and analyze vaccine progress against SARS-CoV, Middle-East respiratory syndrome Coronavirus (MERS-CoV), and SARS-CoV-2, including inactivated vaccines, live attenuated vaccines, subunit vaccines, virus like particles, nucleic acid vaccines, and viral vector vaccines. As SARS-CoV-2, SARS-CoV, and MERS-CoV share the common genus, Betacoronavirus , this review of the major research progress will provide a reference and new insights into the COVID-19 vaccine design and development.
The element identification and imaging methods with a white neutron beam by using different detectors are under development at the Back-n white neutron source of China Spallation Neutron Source. The paper presents the preliminary experimental results with a Micromegas detector. The detector was developed for the beam profile measurements in the Back-n beamline. With upgraded electronics, this system can record the time-of-flight information of the neutrons together with the 2D imaging. The structure of the Micromegas, the improvement of electronics and the experimental setup are presented. A detailed data analysis including the noise suppression, the signal recognition and the event reconstruction are described. In the neutron time-of-flight (TOF) spectrum obtained from the neutron resonance radiography experiment, there are obvious dips due to the resonance absorption of the sample. Subsequently, clear resonance peaks from different elements can be identified form the processed neutron TOF spectrum, which is obtained by subtracting the sample-in spectrum from the sample-out spectrum. By selecting the corresponding resonance peaks, the shapes of different elements including Ag, In and W in a composite sample are successfully identified.
Objective
To investigate the effect of pedicle screw augmentation with bone cement perfusion on the long segment fixation and fusion in the elderly patients with spinal deformity treated by osteotomy.
Methods
The cohort data of the older patients aged ≥70 years with spinal kyphosis were retrospectively analyzed in Beijing Hospital, Department of Orthopedic Surgery, Division of Spine Surgery from January 2012 to June 2014.32 cases with complete clinical date were included in this study.The kyphosis of all patients was secondary to thoracolumbar osteoporotic compression fracture.All patients were treated by posterior thoracolumbar spinal osteotomy with long segment fixation and fusion.The patients with fusions including sacral vertebral body fusion or the T score of BMD were less than-5 were excluded.Some patients with neurological compression symptoms also underwent selective decompression in spinal canal and nerve root foramen.All patients were divided into two groups: with(n=14)versus without(n=18)screw augmentation with bone cement perfusion(augmentation vs.non-augmentation/control group). The follow-up time was no less than 12 months.The data of age, gender, operative time, blood loss volume and preoperative bone mineral density were compared between two groups.Cobb angle of postoperative spinal surgery region, lordosis angle of postoperative lumbar, VAS and ODI improvement were analyzed.Data of surgical fixation and fusion segments were recorded.Pedicle screw loosening was compared between two groups.
Results
In the augmentation group, the pedicle screw loosening didn't occur.But control group showed screw loosening in 7 cases, a euphoric zone around screw in 4 cases, pedicle screw pullout in 2 cases, and vertebral cutting phenomenon with euphotic zone around screw in 1 case.There were no significant differences in ODI improvement rate and surgical satisfaction between the two groups.
Conclusions
When operative procedures of surgeon are in precision and skillful, bone cement augmentation technique for pedicle screw can reduce the occurrence of pedicle screw loosening in older patients during osteotomy and long segment fixation and fusion operation for spinal kyphosis.
Key words:
Spine; Kyphosis; PMMA; Pedicle screw; Osteoporosis
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)