Evaluating Electrode-Tissue Contact Force Using the Moving Pattern of the Catheter Tip and the Electrogram Characteristics

As an important reference for the physician during catheter ablation, the electrode-tissue contact force (CF), is one of the key points for the success of the catheter ablation. With the guide of CF sensing, the ablation procedure can be safer and more effective. Techniques and apparatus have been refined since catheter ablation was invented to treat cardiac arrhythmia. In the review part, different techniques for evaluating the electrode-tissue CF are discussed, including both direct and indirect measurement. Sensor-based direct measurement is broadly applied but restricted by the high cost. Surrogate markers of catheter-tissue contact such as impedance, electrogram (EGM) quality, catheter tip temperature and so on, are taken as reference evaluating CF as well, but each of them has their own drawbacks. In this dissertation, our approach estimating the CF is based on the moving pattern of the catheter tip in the heart chamber. The factors determining the catheter tip motion, include the cardiac and respiratory cycles, blood flow, and so on. If the position of the catheter tip can be recorded, then the motion of the catheter tip can be tracked and analyzed. Based on our collected data, the moving pattern of the catheter tip is different when the electrode-tissue CF level varies. Features extracted from catheter tip motion are significant for CF evaluation. There are different features selected to describe the moving pattern of the catheter tip, which are identified to best represent the movement by checking the corresponding CF as reference. In summary, if the feature has a strong correlation with the CF, then it can be taken as a good feature. Using the features as input, the CF evaluating mechanism is based on a multi-class classification decision tree to make an optimum and comprehensive estimation

Image_1_Preoperative embolization in the treatment of patients with metastatic epidural spinal cord compression: A retrospective analysis.tif

PurposeThe purpose of the study was to assess the effectiveness and safety of preoperative embolization in the treatment of patients with metastatic epidural spinal cord compression (MESCC).MethodsA retrospective analysis of 138 MESCC patients who underwent decompressive surgery and spine stabilization was performed in a large teaching hospital. Among all enrolled patients, 46 patients were treated with preoperative embolization (the embolization group), whereas 92 patients did not (the control group). Patient’s baseline clinical characteristics, surgery-related characteristics, and postoperative neurological status, complications, and survival prognoses were collected and analyzed. Subgroup analysis was performed according to the degree of tumor vascularity between patients with and without preoperative embolization.ResultsPatients with severe hypervascularity experienced more mean blood loss in the control group than in the embolization group, and this difference was statistically significant (P=0.02). The number of transfused packed red cells (PRC) showed a similar trend (P=0.01). However, for patients with mild and moderate hypervascularity, both blood loss and the number of PRC transfusion were comparable across the two groups. Regarding decompressive techniques, the embolization group (64.29%, 9/14) had a higher proportion of circumferential decompression in comparison to the control group (30.00%, 9/30) among patients with severe hypervascularity (P=0.03), whereas the rates were similar among patients with mild (P=0.45) and moderate (P=0.54) hypervascularity. In addition, no subgroup analysis revealed any statistically significant differences in operation time, postoperative functional recovery, postoperative complications, or survival outcome. Multivariate analysis showed that higher tumor vascularity (OR[odds ratio]=3.69, 95% CI [confident interval]: 1.30-10.43, P=0.01) and smaller extent of embolization (OR=4.16, 95% CI: 1.10-15.74, P=0.04) were significantly associated with more blood loss.ConclusionsPreoperative embolization is an effective and safe method in treating MESCC patients with severe hypervascular tumors in terms of intra-operative blood loss and surgical removal of metastatic tumors. Preoperative tumor vascularity and extent of embolization are independent risk factors for blood loss during surgery. This study implies that MESCC patients with severe hypervascular tumors should be advised to undergo preoperative embolization.</p

Engineering BPQDs/PLGA nanospheres-integrated wood hydrogel bionic scaffold for combinatory bone repair and osteolytic tumor therapy

Bone regeneration following the removal of tumor tissues remains a major clinical challenge for the treatment of bone defects, in which materials with combinatory bone repair and osteolytic metastasis therapy is considered as a promising solution. Herein, a highly strong delignified wood/regenerated silk fibroin (RSF) hydrogel scaffold integrated with black phosphorus quantum dots (BPQDs) encapsulated by poly (lactic-co-glycolic acid) (PLGA) was engineered to realize efficient mechanical supporting, bone regeneration, and tumor therapy. Following delignification, the white wood (WW) scaffold significantly improved the mechanical properties of RSF composite hydrogel, with the elastic modulus in the L-direction and R-direction of 300 MPa and 3.3 MPa, and compression modulus in the L-direction of 9.3 MPa. Moreover, the WW/RSF hydrogel scaffold with BPQD/PLGA nanospheres effectively promoted the proliferation, migration, and osteogenic differentiation of bone mesenchymal stem cells and enhanced osteogenesis in vivo. Compared with the vertical implantation method, better bone regeneration was observed in parallel implantation system parallel to bone shaft. Importantly, the BPQDs in the hydrogel scaffolds could inhibit osteoclast differentiation and exhibit photothermal effects against metastatic tumor in the spine. Our data provide promising evidence for the potential therapeutic application on bone regeneration and ablation of bone metastasis.</p

Promoter Methylation-Mediated Silencing of β-Catenin Enhances Invasiveness of Non-Small Cell Lung Cancer and Predicts Adverse Prognosis

<div><p>β-Catenin plays dual role in adhesion complex formation and the Wnt signaling pathway. Although β-catenin expression appears to be upregulated and Wnt signaling pathway is activated in the majority of cancers, its expression level seems to be lost in non-small cell lung cancer (NSCLC). We previously reported that the promoter of β-catenin was hypermethylated in two NSCLC cell lines. In the current study, we expanded our analysis for the methylation status of β-catenin promoter region and its protein expression in seven NSCLC cell lines and a series of 143 cases of primary human lung cancer with adjacent non-neoplastic tissues. Quantitative methylation specific PCR (qMSP) analysis showed methylation of β-catenin promoter region in five NSCLC cell lines, with increased β-catenin protein levels upon 5′-Aza-2′-deoxycytidine (5-aza-dC) treatment. The methylation status in SPC (methylated) and A549 (unmethylated) was confirmed by bisulfite sequencing PCR. 5-Aza-dC treatment inhibited invasiveness of SPC but not A549. Immunofluorescence analysis showed membranous β-catenin expression was lost in SPC and could be re-established by 5-aza-dC, while Wnt3a treatment led to nuclear translocation of β-catenin in both SPC and A549. Dual-luciferase assays indicated that 5-aza-dC treatment caused no significant increase in Wnt signaling activity compared with Wnt3a treatment. The effect of demethylation agent in SPC can be reversed by β-catenin depletion but not E-cadherin depletion which indicated that the methylation mediated β-catenin silencing might enhance NSCLC invasion and metastasis in an E-cadherin independent manner. Subsequent immunohistochemistry results further confirmed that β-catenin promoter hypermethylation correlated with loss of immunoreactive protein expression, positive lymph node metastasis, high TNM stage and poor prognosis. The present study implicates β-catenin promoter hypermethylation in the mechanism of epigenetic changes underlying NSCLC metastasis and progression, thus indicating the potential of β-catenin as a novel epigenetic target for the treatment of NSCLC patients.</p></div

Primer sequences of BSP.

<p>Primer sequences of BSP.</p