Natural killer (NK) cells are programmed to kill target cells without prior antigen priming. Because of their potent cytolytic activities, NK cells are one of the key cell types involved in dismantling allografts. However, in certain transplant models, NK cells also express potent immunoregulatory properties that promote tolerance induction. The precise mechanism for such striking dichotomy remains unknown. In the present study, we showed in a skin transplant model that the skin allografts contain a subset of antigen-presenting cells (APCs) that can home to the recipient mice. We also showed that such graft-derived APCs are usually destroyed by the host NK cells. But in the absence of NK cells, donor APCs can survive and then migrate to the host lymphoid and extralymphoid sites where they directly stimulate the activation of alloreactive T cells. T cells activated in the absence of NK cells are more resistant to costimulatory blockade treatment, and under such conditions stable skin allograft survival is difficult to achieve. Our study identified a novel role for NK cells in regulating T cell priming in transplant models, and may have important clinical implications in tolerance induction.
Calcaneal fractures are rare injuries in children and adolescents, and fractures with displaced intra-articular fracture patterns are even more rare. The purpose of this study was to report 9 intra-articular calcaneal fractures in 8 children (mean age, 12.6 years; range,10-15 years) treated with open reduction and internal fixation (ORIF) and to examine cases reported in the literature to better define the classification characteristics and operational outcomes of this uncommon fracture. Preoperative radiographs and computed tomography scans were used to evaluate and classify the fractures. Clinical and radiographic examinations were performed at postoperative follow-up, and functional outcome was assessed with the modified American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score. Mean follow-up was 47 months (range, 21-72 months). Mean time to union was 9.2 weeks (range, 8-12 weeks). Mean modified AOFAS score was 65.2 points (range, 53-68 points). One foot experienced a minor complication.After a systematic review of the literature, 4 studies with a total of 35 patients (37 fractures) were included. All fractures were caused by high-energy injuries. Based on the Essex-Lopresti classification, 40.5% (15/37) were tongue-type fractures and 59.5% (22/37) were joint depression-type fractures. Based on the Sanders classification, 62.2% (23/37) of fractures were 2 parts, 32.4% (12/37) were 3 parts, and 5.4% (2/37) showed comminution. No significant difference was found in classification information between children and adults. The authors concluded that the characteristics of intra-articular calcaneal fractures in children are similar to those in adults, and operative treatment of these fractures yields good results with few complications.
Perfusable endothelialized models of microfluidic systems that recapitulate unique biological and biophysical microvasculature conditions are improved with micro/nano engineering advances for monitoring of blood hemostasis and thrombosis treatment. Although bio‐sensors and monitoring devices significantly advance in measuring platelet aggregation and thrombosis kinetics, currently platelet aggregation tests still do not meet the arising clinical requirements. Trying to seek new solutions for such a demanding from clinics, the present review provides an overview of design principles of microfluidic systems and micro/nano fabrication strategies in studying the platelet adhesion and aggregation. We critically sketch the characteristics of microfluidic systems to elucidate the role of platelets in the complex process of thrombus formation. The importance, benefits, and challenges of introduced principles and methods are discussed. The potential from various of basic research to clinical applications is also briefly discussed to help guide designing more versatile point‐of‐care devices for hemostasis monitoring and thrombosis diagnosis and treatment.
With the rapid development of information and communication technology, future intelligent transportation systems will exhibit a trend of cooperative driving of connected vehicles. Platooning is an important application technique for cooperative driving. Herein, optimized car-following models for platoon control based on intervehicle communication technology are proposed. On the basis of existing indicators, a series of evaluation methods for platoon safety, stability, and energy consumption is constructed. Numerical simulations are used to compare the effects of three traditional models and their optimized counterparts on the car-following process. Moreover, the influence of homogenous and heterogeneous attributes on the platoon is analyzed. The optimized model proposed in this paper can improve the stability and safety of vehicle following and reduce the total fuel consumption. The simulation results show that a homogenous platoon can enhance the overall stability of the platoon and that the desired safety margin (DSM) model is better suited for heterogeneous platoon control than the other two models. This paper provides a practical method for the design and systematic evaluation of a platoon control strategy, which is one of the key focuses in the connected and autonomous vehicle industry.
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