Ryoji Kiyama

Temperature changes caused by the difference in the distance between the ultrasound transducer and bone during 1 MHz and 3 MHz continuous ultrasound: A phantom study

[Purpose] This study aimed to use a thermograph to observe temperature changes caused by different distances between an ultrasound transducer and bone during 1 MHz and 3 MHz continuous ultrasound emission on a phantom. [Materials and Methods] We observed the distribution of temperature elevations on a phantom consisting of pig ribs and tissue-mimicking material. One megahertz and 3 MHz ultrasound were delivered at 2.0 W/cm2 for 5 minutes. To record the temperature changes on the phantom, we took a screenshot of the thermograph with a digital camera every 20 seconds. [Results] With 1 MHz ultrasound at the distances of 2 and 3 cm, the temperature elevation near the bone was higher than that near the transducer. However, with 3 MHz ultrasound, the temperature elevation was higher near the transducer rather than near the bone. At this point, we consider that there is a possibility of heat injury to internal organs in spite of there being no elevation of skin temperature. [Conclusion] When performing ultrasonic therapy, not only should the frequency be taken into consideration, but also the influence of the absorption coefficient and the reflection of the tissue. We visually confirmed the thermal ultrasound effect by thermography. Special attention to the temperature elevation of the internal organs is necessary to avoid injuries.

Edaravone, a Synthetic Free Radical Scavenger, Enhances Alteplase-Mediated Thrombolysis

The combination of alteplase, a recombinant tissue plasminogen activator, and edaravone, an antioxidant, reportedly enhances recanalization after acute ischemic stroke. We examined the influence of edaravone on the thrombolytic efficacy of alteplase by measuring thrombolysis using a newly developed microchip-based flow-chamber assay. Rat models of embolic cerebral ischemia were treated with either alteplase or alteplase-edaravone combination therapy. The combination therapy significantly reduced the infarct volume and improved neurological deficits. Human blood samples from healthy volunteers were exposed to edaravone, alteplase, or a combination of alteplase and edaravone or hydrogen peroxide. Whole blood was perfused over a collagen- and thromboplastin-coated microchip; capillary occlusion was monitored with a video microscope and flow-pressure sensor. The area under the curve (extent of thrombogenesis or thrombolysis) at 30 minutes was 69.9% lower in the edaravone-alteplase- than alteplase-treated group. The thrombolytic effect of alteplase was significantly attenuated in the presence of hydrogen peroxide, suggesting that oxidative stress might hinder thrombolysis. D-dimers were measured to evaluate these effects in human platelet-poor plasma samples. Although hydrogen peroxide significantly decreased the elevation of D-dimers by alteplase, edaravone significantly inhibited the decrease. Edaravone enhances alteplase-mediated thrombolysis, likely by preventing oxidative stress, which inhibits fibrinolysis by alteplase in thrombi.

Effect of Handrail Height on Sit-To-Stand Movement

Background Care-needing older adults and disabled individuals often require handrails for assistance of movements, such as sit-to-stand movements. Handrails must be set at the appropriate position; however, the effects of handrail height on joint movement and center-of-gravity movements during sit-to-stand movement remain unclear. In the present study, we sought to clarify the effects of handrail height on joint movement, center-of-gravity, and floor reaction force during sit-to-stand movement. Methods Subjects included 16 healthy young adults and 25 older adults who require long-term care. Kinetic and kinematic measurements during sit-to-stand movement of young adults were conducted using a 3-D motion analyzer and a force plate. Trunk forward tilt angle during sit-to-stand movement of older adults was measured using a still image from a video recording. Results Using low handrails, sit-to-stand movement resulted in an increased hip flexion angle, ankle dorsiflexion angle, and trunk forward tilt angle and a greater forward center-of-gravity shift than when not using handrails in young adults during seat-off. In contrast, using high handrails resulted in a smaller hip flexion angle and trunk forward tilt angle in young adults. The backward force on the floor was decreased in the low handrail condition, and was increased in the high handrail condition rather than that of sit-to-stand movement without handrails in young adults. The effect of handrail height on trunk forward tilt angle was the same in both healthy young adults and care-needing older adults during seat-off. Conclusion Because handrail height affects joint movement and shift in the center-of-gravity during sit-to-stand movement, handrail position should be selected to match the status of older adults with functional impairment.

Effect of Foot Progression Angle and Lateral Wedge Insole on a Reduction in Knee Adduction Moment

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle.

Effect of whole body vibration on spasticity in hemiplegic legs of patients with stroke.

Abstract Background: Several reports have focused on the effects of whole body vibration (WBV) on spasticity with differing results. Most studies used modified Ashworth scale (MAS) for qualitative measurements, but the effect was small. Objective: To investigate the effect of WBV on spasticity in hemiplegic legs of patients with stroke using F-wave parameters. Methods: Sixteen patients with stroke (mean age, 54.7 ± 13.5 years: time after stroke, 28.0 ± 26.3 months) were enrolled in a comparative before-and-after intervention trial. WBV was applied at 30 Hz (4–8 mm amplitude) for 5 min on the hamstrings, gastrocnemius, and soleus muscles in a sitting position. Spasticity was assessed according to the F-wave parameters, MAS, and active and passive range of motion (A-ROM and P-ROM, respectively). These assessments were obtained before, immediately after, and 20 min after each intervention. Results: The F-wave parameters, MAS score, and P-ROM improved significantly after the WBV and remained below the baseline level, even after 20 min; no such change was noted in the unaffected limb via the F-wave parameters. The WBV also improved volitional movement immediately after intervention, as indicated by the A-ROM. Conclusions: These results confirmed a significant reduction of motor neuron excitability until 20 min after the WBV, as indicated by F-wave parameters.

Hyperthermic effects of hand bathing: benefits of incorporating finger flexion-extension exercise.

[Purpose] The purpose of our study was to compare the effects of hand bathing using plain water and water supplemented with inorganic salt and carbonated gas and to assess the hyperthermic effects of performing finger flexion-extension exercise while bathing in water with carbonated gas and inorganic salt and without water. [Subjects and Methods] Sixteen healthy, young males were subjected to plain water bathing, CO2 bathing, kineto-CO2 bathing, or no bathing. CO2 bathing involved bathing in a solution of artificial bath additives including inorganic salts and carbon dioxide. Partial bathing of the hand was implemented for 20 minutes at 41 °C. The concentration of carbonic gas was set at 33 ppm. In the kineto-CO2 bathing condition, finger flexion-extension exercise was performed at 60 laps per minute in the same solution used in CO2 bathing. The control group engaged in the same exercise as those in the kineto-CO2 bathing group, but without bathing. [Results] A significant increase in deep-body temperature was observed in the CO2 bathing and kineto-CO2 bathing conditions compared with both the plain water bathing and control condition. [Conclusion] Significantly heightened hyperthermic effects were observed when finger flexion-extension exercise was performed during CO2 bathing.

The Effects of a Lateral Wedge Insole on Knee and Ankle Joints During Slope Walking

The purpose of this study was to determine whether a lateral wedge insole reduces the external knee adduction moment during slope walking. Twenty young, healthy subjects participated in this study. Subjects walked up and down a slope using 2 different insoles: a control flat insole and a 7° lateral wedge insole. A three-dimensional motion analysis system and force plate were used to examine the knee adduction moment, the ankle valgus moment, and the moment arm of the ground reaction force to the knee joint center in the frontal plane. The lateral wedge insole significantly decreased the moment arm of the ground reaction force, resulting in a reduction of the knee adduction moment during slope walking, similar to level walking. The reduction ratio of knee adduction moment by the lateral wedge insole during the early stance of up-slope walking was larger than that of level walking. Conversely, the lateral wedge insole increased the ankle valgus moment during slope walking, especially during the early stance phase of up-slope walking. Clinicians should examine the utilization of a lateral wedge insole for knee osteoarthritis patients who perform inclined walking during daily activity, in consideration of the load on the ankle joint.

Isokinetic trunk and knee muscle strengths and gait performance in walking patients with T-cell lymphotropic virus type 1-associated myelopathy/ tropical spastic paraparesis (HAM/TSP)

The aim of this study was to investigate the isokinetic trunk and knee muscle strengths, and examine the clinical relevance of dynamic muscle strengths and gait performance in walking patients with human T-cell lymphotropic virus type 1-associated myelopathy/ tropical spastic paraparesis (HAM/TSP). Thirteen patients with HAM/TSP (8 females and 5 males, aged 38-76) and 13 sex- and age-matched healthy control subjects participated in the study. We assessed gait speed, stride length, cadence; and maximal isokinetic torque of trunk and knee extensors and flexors at 30°/s, 60°/s and 90°/s using a Biodex System 3 dynamometer. Furthermore, we calculated the isokinetic trunk extensor/flexor (E/F) and hamstrings/quadriceps (H/Q) strength ratios (parameter of the muscle strength balance about the trunk and knee joint). Compared with the age-matched controls, the patients with HAM/TSP had significantly reduced gait speed, stride length and cadence (P < 0.05). Peak torque values related to body weight (PTBW) were significantly reduced, especially for the knee flexors (P < 0.05). For the knee extensors, the PTBW values were significantly reduced at an increased angular velocity (P < 0.05). The PTBW of knee flexors was positively correlated with gait speed and cadence in the patients with HAM/TSP. The H/Q ratio but not E/F ratio was significantly decreased compared with the control. Our results indicated that the isokinetic trunk and knee muscle performance had reduced from the ambulatory stage, and suggested the deterioration in knee muscle performance to be associated with gait disturbance in walking HAM/TSP patients.

Uric acid enhances alteplase-mediated thrombolysis as an antioxidant

Uric acid (UA) therapy may prevent early ischemic worsening after acute stroke in thrombolysis patients. The aim of this study was to examine the influence of UA on the thrombolytic efficacy of alteplase in human blood samples by measuring thrombolysis under flow conditions using a newly developed microchip-based flow-chamber assay. Human blood samples from healthy volunteers were exposed to UA, alteplase, or a combination of UA and alteplase. Whole blood and platelet-rich plasma were perfused over a collagen- and thromboplastin-coated microchip, and capillary occlusion was monitored with a video microscope and flow-pressure sensor. The area under the curve (extent of thrombogenesis or thrombolysis) at 30 minutes was 92% lower in the UA–alteplase-treated group compared with the alteplase-treated group. D-dimers were measured to evaluate these effects in human platelet-poor plasma samples. Although hydrogen peroxide significantly decreased the elevation of D-dimers by alteplase, UA significantly inhibited the effect of hydrogen peroxide. Meanwhile, rat models of thromboembolic cerebral ischemia were treated with either alteplase or UA–alteplase combination therapy. Compared with alteplase alone, the combination therapy reduced the infarct volume and inhibited haemorrhagic transformation. UA enhances alteplase-mediated thrombolysis, potentially by preventing oxidative stress, which inhibits fibrinolysis by alteplase in thrombi.

Estimation of Gait Independence Using a Tri-Axial Accelerometer in Stroke Patients

The purpose of this study was to clarify whether a gait analysis using an accelerometer could estimate gait independence. Eighty-six stroke patients and 21 healthy control subjects participated in this study. Stroke patients were identified as dependent or independent based on their gait ability. The acceleration of the trunk and bilateral thigh was measured using three wireless sensors during walking. The root mean square, gait regularity, and symmetry were calculated from the acceleration to estimate gait quality. ANCOVA showed that gait regularity of the trunk and bilateral thigh were significantly lowest in the dependent group, regardless of gait velocity. A logistic regression analysis showed that the regularity and root mean square of the anteroposterior acceleration of the unaffected thigh were the key factors for estimating gait independence. This study suggests that an acceleration-based gait analysis facilities gait independence estimation, and is a useful tool during the rehabilitation of stroke patients.