Application of Remote Ischemic Preconditioning in Patients Undergoing Chemotherapy with Anthracyclines

Background: The most active agents for the treatment of breast cancer are the anthracyclines whose clinical usefulness is limited by cumulative dose-dependent cardiotoxicity, which results in congestive heart failure among other limiting factors. With all the attempts to minimize chemotherapeutic cardiotoxicity, remote ischemic preconditioning (RIPC) has been considered as a potent endogenous mechanism capable of inhibiting inflammatory responses. Objective: This study aimed to verify if RIPC may be effective as prophylaxis to prevent anthracycline- induced cardiotoxicity in oncological patients. Methods: The preconditioning method was based on four to five-minute cycles of a blood pressure cuff insufflation around the upper arm (either left or right) from 200 mmHg to 250 mmHg, inducing ischemic intervals interspersed with 5 minutes of reperfusion. Results: In this work, echocardiogram results showed a ventricular mass variation that can get worse during chemotherapeutic treatment; however, in patients who had been undergoing RIPC sessions over a period of 6 months, it was observed that this change did not occur. The parameters for troponin T levels were considered; they were higher in patients who were not undergoing RIPC in relation to those who were. When both cases were compared, it was possible to infer that there was a clinically significant improvement for those who went through the procedure. Conclusion: Thus, through the analysis of this study, it is possible to conclude that RIPC is a lowcost, non-invasive procedure which brings cardiac protection for patients undergoing chemotherapy with anthracyclines, providing support in the treatment of cancer.

Research progress of high-performance BEM and investigation on convergence of GMRES in local stress analysis of slender real thin-plate beams

Purpose Based on the error analysis, the authors proposed a new kind of high accuracy boundary element method (BEM) (HABEM), and for the large-scale problems, the fast algorithm, such as adaptive cross approximation (ACA) with generalized minimal residual (GMRES) is introduced to develop the high performance BEM (HPBEM). It is found that for slender beams, the stress analysis using iterative solver GMRES will difficult to converge. For the analysis of slender beams and thin structures, to enhance the efficiency of GMRES solver becomes a key problem in the development of the HPBEM. The purpose of this paper is study on the preconditioning method to solve this convergence problem, and it is started from the 2D BE analysis of slender beams. Design/methodology/approach The conventional sparse approximate inverse (SAI) based on adjacent nodes is modified to that based on adjacent nodes along the boundary line. In addition, the authors proposed a dual node variable merging (DNVM) preprocessing for slender thin-plate beams. As benchmark problems, the pure bending of thin-plate beam and the local stress analysis (LSA) of real thin-plate cantilever beam are applied to verify the effect of these two preconditioning method. Findings For the LSA of real thin-plate cantilever beams, as GMRES (m) without preconditioning applied, it is difficult to converge provided the length to height ratio greater than 50. Even with the preconditioner SAI or DNVM, it is also difficult to obtain the converged results. For the slender real beams, the iteration of GMRES (m) with SAI or DNVM stopped at wrong deformation state, and the computation failed. By changing zero initial solution to the analytical displacement solution of conventional beam theory, GMRES (m) with SAI or DNVM will not be stopped at wrong deformation state, but the stress error is still difficult to converge. However, by GMRES (m) combined with both SAI and DNVM preconditioning, the computation efficiency enhanced significantly. Originality/value This paper presents two preconditioners: DNVM and a modified SAI based on adjacent nodes along the boundary line of slender thin-plate beam. In the LSA, by using GMRES (m) combined with both DNVM and SAI, the computation efficiency enhanced significantly. It provides a reference for the further development of the 3D HPBEM in the LSA of real beam, plate and shell structures.