Clear cell renal cell carcinoma (ccRCC), the most common malignant subtype of renal cell carcinoma, is characterized by the accumulation of lipid droplets in the cytoplasm. RNASET2 is a protein coding gene with a low expression level in ovarian cancers, but it is overexpressed in poorly differentiated neuroendocrine carcinomas. There is a correlation between RNASET2 upregulation and triglyceride expression levels in human serum but is unknown whether such an association is a factor contributing to lipid accumulation in ccRCC. Herein, we show that RNASET2 expression levels in ccRCC tissues and cell lines are significantly higher than those in both normal adjacent tissues and renal tubular epithelial cells. Furthermore, its upregulation is associated with increases in ccRCC malignancy and declines in patient survival. We also show that an association exists between increases in both cytoplasmic lipid accumulation and HIF‐2α transcription factor upregulation, and increases in both RNASET2 and triglyceride expression levels in ccRCC tissues. In addition, DGAT1 and DGAT2, two key enzymes involved in triglyceride synthesis, are highly expressed in ccRCC tissues. By contrast, RNASET2 knockdown inhibited their expression levels and lowered lipid droplet accumulation, as well as suppressing in vitro cell proliferation, cell invasion, and migration. In conclusion, our data suggest HIF2α upregulates RNASET2 transcription in ccRCC cells, which promotes both the synthesis of triglycerides and ccRCC migration. As such, RNASET2 may have the potential as a biomarker or target for the diagnosis and treatment of ccRCC.
This paper presents a novel parallel architecture with seven active degrees of freedom (DOFs) for general-purpose haptic devices. The prime features of the proposed mechanism are partial decoupling, large dexterous working area, and fixed actuators. The detailed processes of design, modeling, and optimization are introduced and the performance is simulated. After that, a mechanical prototype is fabricated and tested. Results of the simulations and experiments reveal that the proposed mechanism possesses excellent performances on motion flexibility and force feedback. This paper aims to provide a remarkable solution of the general-purpose haptic device for teleoperation systems with uncertain mission in complex applications.
Passive gravity compensation can effectively reduce the load of actuators, but existing methods are commonly complex in terms of mechanisms and elastic systems with Zero-Free-Length (ZFL) property. A compensation strategy using all joint information is further developed in this paper, as well as the involved elastic system. This approach with considerable compensation effect is simple in principle, and the ZFL property is precisely and completely realized by commercial springs. Compared with the previous method, the process of spring selection is also greatly simplified. Possible arrangements with approximate compensation are also calculated and discussed to achieve a compromise between the compensation effect and the mechanism complexity. The elastic system for Delta-like is implemented and calibrated as an illustration. The results show that the stiffness error rate is reduced from 23.53% to 3.92% and the compensation effect is improved by 63.36% for full compensation and 24.01% for approximate compensation respectively.
Haptic devices are applied as masters to provide force displays for telemedicinal robots. Gravity compensation has been proven to be crucial for the accuracy and capability of force displays, which are critical for haptic devices to assist operators. Therefore, the existing method suffers from an unsatisfactory effect, a complex implementation, and low efficiency. In this paper, an approach combining active and passive gravity compensation is proposed to improve the performance of a force display. The passive compensation is conducted by counterweights fixed with the moving platform and pantographs to offset most of the gravity and reduce the loads of the motors, while the peak capability of the force display is enhanced. The required weight is optimized by a multi-objective genetic algorithm in terms of the maximum torque of the motors in the global workspace. As a supplement, the residual gravity is eliminated by active compensation to extend the accuracy of the force display. The balancing forces in the discretized workspace are entirely calibrated, and the required force for the arbitrary configuration is calculated by interpolations. The decisions regarding the algorithm parameters are also discussed to achieve a compromise between the effect and elapsed time. Finally, the prototype with a compensation mechanism is implemented and experiments are carried out to verify the performance of the proposed method. The results show that the peak capability of the force display is enhanced by 45.43% and the maximum deviation is lowered to 0.6 N.
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