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This simulation study was designed to predict the torsadogenicity of sevoflurane and propofol in healthy control, as well as type 1 and type 2 long QT syndrome (LQT1 and LQT2, respectively), using the O'Hara-Rudy dynamic model. LQT1 and LQT2 models were simulated by decreasing the conductances of slowly and rapidly activating delayed rectifier K.sup.+ currents (I.sub.Ks and I.sub.Kr, respectively) by 50%, respectively. Action potential duration at 50% repolarization level (APD.sub.50) and diastolic intracellular Ca.sup.2+ concentration were measured in epicardial cell during administration of sevoflurane (1 ~ 5%) and propofol (1 ~ 10 [mu]M). Torsadogenicity can be predicted from the relationship between APD.sub.50 and diastolic intracellular Ca.sup.2+ concentration, which is classified by the decision boundary. Whereas the relationships in control and LQT1 models were distributed on nontorsadogenic side in the presence of sevoflurane at all tested concentrations, those in LQT2 models were shifted to torsadogenic side by concentrations of [greater than or equal to] 2%. In all three models, propofol shifted the relationships in a direction away from the decision boundary on nontorsadogenic side. Our findings suggest that sevoflurane, but not propofol, exerts torsadogenicity in patients with reduced I.sub.Kr, such as LQT2 patients. Caution should be paid to the occurrence of arrhythmia during sevoflurane anesthesia in patients with reduced I.sub.Kr., Author(s): Akiko Kojima [sup.1], Yutaka Fukushima [sup.1], Hiroshi Matsuura [sup.2] Author Affiliations: (1) https://ror.org/00d8gp927, grid.410827.8, 0000 0000 9747 6806, Department of Anesthesiology, Shiga University of Medical Science, , 520-2192, Otsu, [...]

To study mechanisms of jet atomization, a novel method of experimentation utilizing the resonation of diaphragms made from thin steel plates has been previously developed. In the experiments, a diaphragm covered by a film of water emitted acoustic sounds, and jet atomization from the water film was observed. Experiments using diaphragms composed of different materials and fast Fourier transformation analysis of the acoustic sound revealed that jet atomization occurred under limited surface conditions of the diaphragm and a specific range of frequency. In this article, the dynamics of a resonating body composed of the diaphragm and water film were analyzed using the finite element method with a combination of theoretical analyses of surface waves of water, such as the well-known Lang's equation. The present FEA results, from harmonic response analyses with consideration of viscous damping effect due to interaction between the diaphragm and water film, precisely confirmed the results of FFT analysis previously obtained by the experiment. Specifically, the peak frequency of the frequency response agreed well with the FFT results, and the shift of the peak frequency and attenuation due to the interaction in the analyses corresponded with the difference in surface conditions between the hydrophilic and hydrophobic materials of the diaphragm in the experiments. Our interpretation of the mechanism of jet atomization is expanded by the present numerical results. [ABSTRACT FROM AUTHOR]

In this study, the mechanisms of jet atomization were analyzed based on a frequency analysis of atomization sounds in the audible range (∼20 kHz). Jet atomization is a two-dimensional, high-speed atomization using a diaphragm, and interesting acoustic signals and atomization phenomena were detected on hydrophobic and hydrophilic diaphragms. The hydrophilic diaphragm strongly interacted and resonated with the surface wave, resulting in symmetrical jet atomization relative to the diaphragm. The resonance between the diaphragm and the surface wave was supported by a calculation of the eigenfrequency of the diaphragm and the coincidence of the droplet diameters as calculated from Lang's equation. Notably, the diaphragm excited by the ultrasonic transducer acted as a new transducer vibrating perpendicular to the transducer. As a result, when the diaphragm and the surface wave were in resonance at 2.4 MHz, a symmetrical two-dimensional high-speed jet atomization was generated in the direction perpendicular to the transducer's vibration direction. This study also revealed that the atomization state can be determined based on the acoustic analysis. This acoustic analysis of atomization sounds can be applied in more advanced atomization control, such as for providing uniform dispersions of droplets containing DNA, drugs, or microplastics. [ABSTRACT FROM AUTHOR]

Aim: Postoperative dysphagia after emergency abdominal surgery (EAS) in patients of advanced age has become problematic, and appropriate dysphagia management is needed. This study was performed to identify predictive factors of dysphagia after EAS and to explore the usefulness of swallowing screening tools (SSTs). Methods: This retrospective study included 267 patients of advanced age who underwent EAS from 2012 to 2022. They were assigned to a dysphagia group and non‐dysphagia group using the Food Intake Level Scale (FILS) (dysphagia was defined as a FILS level of <7 on postoperative day 10). From 2018, original SSTs including a modified water swallowing test were performed by nurses. Results: The incidence of postoperative dysphagia was 22.8% (61/267). Patients were significantly older in the dysphagia than non‐dysphagia group. The proportions of patients who had poor nutrition, cerebrovascular disorder, Parkinson's disease, dementia, nursing‐care service, high intramuscular adipose tissue content (IMAC), and postoperative ventilator management were much higher in the dysphagia than non‐dysphagia group. Using logistic regression analysis, high IMAC, postoperative ventilator management, cerebrovascular disorder, and dementia were correlated with postoperative dysphagia and were assigned 10, 4, 3, and 3 points, respectively, according to each odds ratio. The optimal cut‐off value was 7 according to a receiver operating characteristics curve. Using 1:1 propensity score matching for high‐risk patients, the incidence of postoperative dysphagia was reduced by SSTs. Conclusions: The new prediction score obtained from this study can identify older patients at high risk for dysphagia after EAS, and SSTs may improve these patients' short‐term outcomes. This retrospective study included 267 patients of advanced age and was performed to identify predictive factors of dysphagia after emergency abdominal surgery and to explore the usefulness of swallowing screening tools. This study demonstrated that high intramuscular adipose tissue content, postoperative ventilator management, cerebrovascular disorder, and dementia were associated with postoperative dysphagia after emergency abdominal surgery in patients of advanced age. For patients at high risk as identified by our new prediction score that was created based on these risk factors, propensity score‐matching analysis showed that the use of swallowing screening tools can help to prevent postoperative dysphagia. [ABSTRACT FROM AUTHOR]

The effect of terahertz (THz) radiation has been studied in medicine. However, there is a lack of scientific information regarding its possible mutagenicity. Therefore, the present study aimed to assess the mutagenicity of 1.6 THz laser irradiation. The Ames test was conducted using five bacterial tester strains. The bacteria were subjected to (i) 1.6 THz laser irradiation at 3.8 mW/cm2 for 60 min using a tabletop THz pulse laser system, (ii) ultraviolet irradiation, (iii) treatment with positive control chemicals (positive control) or (iv) treatment with the solvent used in the positive control (negative control). After treatment, the bacterial suspensions were cultured on minimal glucose agar to determine the number of revertant colonies. In addition, the comet assay was performed using fibroblasts (V79) to assess possible DNA damage caused by the THz laser irradiation. The Ames test demonstrated that the THz laser irradiation did not increase the number of revertant colonies compared to that in the negative control group, whereas the ultraviolet irradiation and positive control treatment increased the number of revertant colonies. Thus, 1.6 THz laser irradiation is unlikely to be mutagenic. The comet assay additionally suggests that the THz laser irradiation unlikely induce cellular DNA damage. [ABSTRACT FROM AUTHOR]