The effects of resistance exercise and leucine-enriched essential amino acid supplementation on muscle mass and physical function in post-gastrectomy patients: a pilot randomized controlled trial.

[Purpose] In gastric cancer patients, low muscle mass decreases overall survival and quality of life (QOL). Resistance exercise with leucine-enriched essential amino acid (LEAA) supplementation may prevent muscle mass loss. This study was aimed at determining whether resistance exercise with LEAA supplementation prevents muscle mass loss in post-gastrectomy patients. [Participant and Methods] We conducted a single-center, open-label, randomized controlled pilot trial. Ten participants who underwent gastrectomy were divided into two groups. The intervention group underwent resistance exercise at 70% of one repetition maximum and received a supplement of 3 g of LEAA twice daily for 15 days, while the control group received standard care. We compared changes in muscle mass, physical function (muscle strength and continuous walking distance), and QOL between the groups. [Results] We found good adherence and participation rates in both groups. We failed to detect a significant difference in muscle mass between the groups. The intervention group showed significant improvements in muscle strength and QOL, while the control group showed no significant changes. [Conclusion] We failed to detect a significant difference in muscle mass due to resistance exercise with LEAA supplementation in post-gastrectomy patients. However, resistance exercise with LEAA supplementation might be beneficial for muscle strength recovery and QOL improvements.

A Successful Case of Switching Treatment from Ketamine to Methadone for Complex Neuropathic Pain.

Background: Methadone is frequently used for the management of complex pain at the end of life by palliative care specialists. It is also used in low doses as an add-on therapy to chronic opioid treatment of cancer-related pain, usually with good effect, and without any reported severe adverse effects. However, there are few reports of switching from ketamine to methadone. Case: We report a case of a patient with rectal cancer and intractable pain. Switching from ketamine to methadone to maintain analgesia was successfully carried out without impacting activities of daily living. Established measurement tools, such as numerical rating scale, Douleur Neuropathique, Functional Independence Measure, and Barthel Index, were used. Conclusion: Switching from ketamine to methadone may be beneficial in relieving refractory cancer-related neuropathic pain without decreasing functioning.

Ultrasound radiation from a three-layer thermoacoustic transformation device.

A thermophone is a thermoacoustic transducer, which generates sound via time-varying Joule heating of an electrically conductive layer, which leads to expansion and contraction of a small pocket of air near the surface of the film. In this work, a 10-µm-thick Ag-Pd conductive film was coupled with heat-insulating and heat-releasing layers to fabricate a three-layer thermophone for generating ultrasound. The heat-insulating layer was 47 µm thick, and was made of glass. The heat-releasing layer was 594 µm thick, and was made of 94% alumina. Because of the simple sound-generation mechanism, which does not require mechanical moving parts, the Ag-Pd conductive film on the glass substrate can produce ultrasound radiation with broadband frequency characteristics, where exiting commercial electrode materials were used. We also demonstrate that the measured directivity patterns are in good agreement with theoretical predictions, assuming a rectangular diaphragm with the same size as the metallic film.

Experimental study on the pressure and pulse wave propagation in viscoelastic vessel tubes-effects of liquid viscosity and tube stiffness.

A pulse wave is the displacement wave which arises because of ejection of blood from the heart and reflection at vascular bed and distal point. The investigation of pressure waves leads to understanding the propagation characteristics of a pulse wave. To investigate the pulse wave behavior, an experimental study was performed using an artificial polymer tube and viscous liquid. A polyurethane tube and glycerin solution were used to simulate a blood vessel and blood, respectively. In the case of the 40 wt% glycerin solution, which corresponds to the viscosity of ordinary blood, the attenuation coefficient of a pressure wave in the tube decreased from 4.3 to 1.6 dB/m because of the tube stiffness (Young's modulus: 60 to 200 kPa). When the viscosity of liquid increased from approximately 4 to 10 mPa·s (the range of human blood viscosity) in the stiff tube, the attenuation coefficient of the pressure wave changed from 1.6 to 3.2 dB/m. The hardening of the blood vessel caused by aging and the increase of blood viscosity caused by illness possibly have opposite effects on the intravascular pressure wave. The effect of the viscosity of a liquid on the amplitude of a pressure wave was then considered using a phantom simulating human blood vessels. As a result, in the typical range of blood viscosity, the amplitude ratio of the waves obtained by the experiments with water and glycerin solution became 1:0.83. In comparison with clinical data, this value is much smaller than that seen from blood vessel hardening. Thus, it can be concluded that the blood viscosity seldom affects the attenuation of a pulse wave.

Noninvasive assessment of arterial stiffness by pulse wave analysis.

Pulse wave evaluation is an effective method for arteriosclerosis screening. The pulse wave comprises two displacement components, the incident wave ε(i)(t) and the reflected wave ε(r)(t). Because the amplitude of the reflected wave changes markedly with arterial stiffness, analysis of this wave is useful for evaluation of such stiffness. In this paper, a noninvasive method for extracting the reflected component from a pulse wave is proposed. First, the pulse wave ε(i)(t) + ε(r)(t) and blood flow velocity u(i)(t) - u(r)(t) were measured at the common carotid artery. A new approach is used to estimate the displacement wave ε(i)(t) -ε(r)(t), in which a transform of the conservation of mass, an elastic tube model, and a Voigt model for a viscoelastic body are applied to blood flow velocity data. Twice the amplitude of the reflected wave [TARW; 2ε(r)(t)] was obtained by subtracting the amplitude of the calculated displacement wave from that of the observed pulse wave. This method was applied to subjects aged from their 20s to 60s to evaluate differences in the reflected component. The results indicate moderate correlation between age and TARW (R(2) = 0.65). To evaluate the validity of this method for screening arterial stiffness, we compared TARW with existing diagnostic indices pulse wave velocity (PWV) and cardio-ankle vascular index (CAVI). TARW was moderately correlated with PWV (R(2) = 0.48) and CAVI (R(2) = 0.71). Therefore, this new method has potential for diagnosing arterial stiffness.

One-dimensional model for propagation of a pressure wave in a model of the human arterial network: comparison of theoretical and experimental results.

Pulse wave evaluation is an effective method for arteriosclerosis screening. In a previous study, we verified that pulse waveforms change markedly due to arterial stiffness. However, a pulse wave consists of two components, the incident wave and multireflected waves. Clarification of the complicated propagation of these waves is necessary to gain an understanding of the nature of pulse waves in vivo. In this study, we built a one-dimensional theoretical model of a pressure wave propagating in a flexible tube. To evaluate the applicability of the model, we compared theoretical estimations with measured data obtained from basic tube models and a simple arterial model. We constructed different viscoelastic tube set-ups: two straight tubes; one tube connected to two tubes of different elasticity; a single bifurcation tube; and a simple arterial network with four bifurcations. Soft polyurethane tubes were used and the configuration was based on a realistic human arterial network. The tensile modulus of the material was similar to the elasticity of arteries. A pulsatile flow with ejection time 0.3 s was applied using a controlled pump. Inner pressure waves and flow velocity were then measured using a pressure sensor and an ultrasonic diagnostic system. We formulated a 1D model derived from the Navier-Stokes equations and a continuity equation to characterize pressure propagation in flexible tubes. The theoretical model includes nonlinearity and attenuation terms due to the tube wall, and flow viscosity derived from a steady Hagen-Poiseuille profile. Under the same configuration as for experiments, the governing equations were computed using the MacCormack scheme. The theoretical pressure waves for each case showed a good fit to the experimental waves. The square sum of residuals (difference between theoretical and experimental wave-forms) for each case was <10.0%. A possible explanation for the increase in the square sum of residuals is the approximation error for flow viscosity. However, the comparatively small values prove the validity of the approach and indicate the usefulness of the model for understanding pressure propagation in the human arterial network.