Biomechanical analysis of fractures in the mandibular neck (collum mandibulae)

After treatment of fractures in the neck of the mandible by means of immobilization of the dentition, often more or less severe manifestations of malocclusion remain. It was hypothesized that this is caused by an altered articulation in the jaw joint on the affected side. Furthermore, it was hypothesized that an anteriorly displaced condyle, as observed frequently as a side effect of the treatment, is caused by pull of the lateral pterygoid muscle, despite maxillomandibular fixation.Intervention experiments were performed in silico to test these hypotheses. With a biomechanical model of the human masticatory system alterations were applied mimicking a fractured mandibular neck and configurations that had been observed after healing.It was predicted that the altered articulation in the jaw joint caused asymmetrical jaw movements despite symmetrical muscle activation. The jaw was predicted to close with an open bite similar to clinical observations. The predicted laterodeviations, however, were not in accordance with clinical observations. Despite maxillo-mandibular fixation the lateral pterygoid muscle was able to pull the mandibular condyle out of its fossa in anterior direction. Consequently, despite some methodological limitations, in general the predictions corroborated the hypotheses.     

Preoperative neutrophil-to-lymphocyte ratio is a more valuable prognostic factor than platelet-to-lymphocyte ratio for nonmetastatic rectal cancer

Several combinations of inflammatory factors, including neutrophil-to- lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), have been reported to be prognostic factors in various malignant tumors, including colorectal cancer (CRC). The aim of this study was to evaluate the prognostic value of NLR and PLR for patients with rectal cancer (RC) who underwent curative surgery. Data from patients who underwent curative resection for RC were retrospectively reviewed. The cutoff for NLR and PLR was defined as 2.3 and 144 by receiver operating characteristic (ROC) curve. Overall survival (OS) and disease-free survival (DFS) were assessed using Kaplan-Meier method. Multivariable Cox regression model was used to evaluate the independent prognostic significance of variables. A total of 140 patients were eligible in the study. High NLR (> 2.3) and high PLR (> 144) both predicted lower OS and DFS according to Kaplan-Meier method. But in the multivariable Cox regression model, only the high NLR retained significance for reduced OS and DFS. According to Chi-square test, patients with higher NLR had larger tumor size and higher pN-stage. While PLR was only associated with the pN-stage. High preoperative NLR was shown to be a negative independent prognostic factor in patients undergoing resection for nonmetastatic RC. It may be helpful as a factor to guide the postoperative therapies.     

Differential responsiveness of the right parahippocampal region to electrical stimulation in fixed human brains: Implications for historical surgical stimulation studies?

If structure dictates function within the living human brain, then the persistence of specific responses to weak electric currents in fixed, deceased brains could reflect “hardwired” properties. Different key structures from the left and right hemispheres of brains that had been fixed for over 20 years with ethanol–formalin–acetic acid were stimulated with either 1-Hz, 7-Hz, 10-Hz, 20-Hz, or 30-Hz, sine-wave, square-wave, or pulsed currents while needle-recorded quantitative electroencephalographic responses were obtained. Differential responses occurred only within the right hippocampus and parahippocampal gyrus. The right hippocampus displayed frequency-independent increases in gamma power relative to the left hemispheric homologue. The parahippocampal region responded exclusively to 7-Hz pulsed currents with wideband (8–30 Hz) power. These profiles are consistent with dynamic connections associated with memory and consciousness and may partially explain the interactions resultant of pulse type and hemisphere for experiential elicitations during the golden age of surgical stimulations. The results also indicate that there may be an essential “hardwiring” within the human brain that is maintained for decades when it is fixed appropriately.     

Increasing radiofrequency ablation volumes with the use of internally cooled electrodes and injected hydrochloric acid in ex vivo bovine livers

Purpose: We used an impedance-controlled generator with an internally cooled electrode to perform radiofrequency ablation (RFA) in ex vivo bovine livers, with a single injection of either 38.5% sodium chloride (NaCl) or 10% hydrochloric acid (HCl), to determine the relative effects of these two solutions on tissue impedance, temperature and ablation volume.

Materials and methods: We performed 10 ablations each with injections of NaCl (NaCl-RFA), HCl (HCl-RFA) or nothing (RFA-alone), with a power setting of 200 W for 15?minutes. We recorded tissue impedance before and after injection. We logged temperatures obtained from thermocouple probes positioned 5, 10, 15 and 20?mm from the internally cooled RF electrode. After ablation, we measured ablation zone longitudinal and transverse diameters, and we calculated a spherical ratio (SR) for each ablation.

Results: Mean post-injection impedance of 30.3 (standard deviation [SD] 2.5) ohms for HCl was significantly lower than that of 55.4 (SD 3.5) ohms for NaCl (p?<?.001). Mean maximum temperatures recorded at each respective distance from the RFA electrode were all highest for HCl-RFA and lowest for RFA-alone (p?<?.001). Mean longitudinal and transverse diameters after HCl-RFA (5.50 [SD 0.25] cm and 5.28 [SD 0.22] cm, respectively) were significantly larger than those after NaCl-RFA (4.24 [SD 0.35] cm and 3.55 [SD 0.43] cm, respectively) and after RFA-alone (3.60 [SD 0.10] cm and 2.70 [SD 0.13] cm, respectively) (p?<?.001). Mean SR after HCl-RFA (0.93, SD 0.02) was significantly higher than mean SR after NaCl-RFA (0.76, SD 0.06) and RFA-alone (0.72, SD 0.04) (p?<?.001).

Conclusion: Monopolar, impedance-controlled RFA, with an internally cooled electrode and a single 10% HCl injection may allow larger tumors to be treated, potentially resulting in improved patient outcomes.     

DVH预测模型在VMAT计划培训中的应用

目的:以宫颈癌为例，探索使用剂量体积直方图（DVH）预测模型培训放疗物理师容积旋转调强（VMAT）计划设计的可行性及其效果。方法:随机选取20例宫颈癌测试病例对3名见习物理师进行两个阶段培训（第一阶段15例，第二阶段5例）。每位物理师分别采用两种方法设计VMAT计划:传统人工计划（MP）和基于DVH预测模型引导的自动计划（KBP）。对比不同阶段两种计划靶区和危及器官的各种剂量学参数，并做相应统计分析。结果:与人工计划相比，自动计划在明显提高PGTV靶区V60覆盖（P<0.001），改善高剂量控制（V66）（P=0.027）的情况下，显著降低膀胱（P<0.001）、直肠（P<0.001）、左右肾（P=0.001和P<0.001）以及左右侧股骨头（P<0.001和P<0.001）等绝大部分正常组织器官的受照剂量。在提高计划合格率的同时，亦减小了计划者间的质量差异。结论:DVH预测模型有助于深化物理师对VMAT初始优化参数设置的理解，加快培训进度，提升VMAT计划设计水平。     

International Study Group of Pancreatic Surgery type 3 and 4 venous resections in patients with pancreatic adenocarcinoma:the Paoli-Calmettes Institute experience

IntroductionA new neoadjuvant regimen, together with more aggressive surgeries, appears to have increased the resectability rate in patients with pancreatic ductal adenocarcinoma (PDAC). Our study aimed to evaluate the outcomes of patients who underwent venous resection (VR) during pancreatectomies for PDAC.Materials and methodsBetween 2005 and 2017, 130 patients underwent pancreatectomies with type 3 or 4 (i.e., segmental resection without or with graft interposition, respectively) VR for PDAC. Patients’ characteristics, surgical techniques, perioperative management, pathological findings, and outcomes were recorded and compared during 2 inclusion periods: the landmark year for the introduction of the FOLFIRINOX regimen and the hyperspecialization of our pancreatic-surgery team was 2010.ResultsPerformance of pancreatectomies with VR steadily increased through the 2 inclusion periods. In the overall series (n = 130), the median overall survival time and the 5-year survival proportion were 26.3 months and 21%, respectively. Upon multivariate analysis, ASA score 3 (P = 0.01) and R1 resection margins (P < 0.01) were found to be negative independent factors influencing survival. Patients who underwent upfront VR (n = 47) had survival rates similar to those of patients who received neoadjuvant treatment (n = 83). After 2010, more complex VR were performed; however, no difference was found between the 2 periods with respect to postoperative courses, pathologic findings, or survival after a matching process based on patients’ characteristics and tumor stages.ConclusionOver the last 2 decades, VR during pancreatectomy has been confirmed as a safe procedure despite the increase in technical complexity. Disappointingly, we did not observe any dramatic survival improvement.     

Rebuilding trust

Lack of trust is a major problem in our current health care system and is increasingly becoming a focus in the literature and in national discussions on how to better understand, address, and resolve. In this narrative essay, I share how I wrestled with rebuilding trust after my own adverse experiences with medical error, surgery complications, and communication challenges. This perspective highlights the critical importance of physician communication and trust in the patient-physician relationship.     

Haematic silicon in drowning

The aim of this paper was to evaluate silicon (Si) concentration in human whole ventricular blood as a further potential chemical marker in the diagnosis of drowning. We employed an acidic digestion for the extraction of soluble Si, and an alkaline digestion for the determination of total Si, including particulate matter, both arising from drowning medium. 29 suspected drowning situations, 24 in fresh water (Fw) and 5 in seawater (Sw), were examined. The difference in Si concentration between the left and right ventricular blood (Si Δ_L–R) was measured and alkaline Si Δ_L–R seems, indeed, a potentially significant complementary tool in the diagnosis of Fw drowning, because insoluble silicon fraction does not undergo hemo-dilution or hemo-concentration, and the Δ_L–R is not affected by exogenous factors. In spite of the limited number of cases investigated, a good correlation was observed between the analytical results and the macro-microscopic autoptic findings.