Preliminary gait analysis of frail versus older adults.

[Purpose] This study aimed to verify the usefulness of an inertial measurement unit and compare the gait of frail and robust older adults. [Participants and Methods] Six participants (three males and three females) in their 80s were diagnosed as frail or robust according to Japanese Cardiovascular Health Study criteria. Using an inertial measurement unit, we measured parameters associated with the sole clearance and center of gravity shift. We then calculated the margin of stability in two directions. [Results] The gait analysis of both groups was reliable, as intraclass correlation coefficient values were comparable to the measurement accuracy of the inertial measurement unit achieved in a previous study of young participants. The results revealed that the sole clearance during the swing phase tended to be lower in frail than robust participants; moreover, the center of mass shift tended to be small and step width wide in frail participants, whereas the center of mass shift tended to be large in robust participants. [Conclusion] Our findings are expected to contribute to gait training in rehabilitation programs for older frail adults, the development of welfare equipment such as walking aids for frail elderly individuals, and the establishment of the reliability of inertial measurement unit use.

Effect of forward moment on recovery motion against tripping.

Investigating the fall recovery motion mechanism is crucial to prevent fall injuries. Among the various parameters of motion and posture, the forward moment can be considered the representative parameter of the magnitude of tripping from a kinematic perspective. The effect of increasing the forward moment on the recovery motion after tripping was investigated in this study. A tripping experiment was performed on a treadmill, and the recovery motion was observed. The forward moment was artificially increased using several approaches, such as pulling the torso, increasing gait speed, and increasing body mass. Factor analysis was performed to establish the relationship between the recovery motion parameters and forward moment. The distribution of the factor scores implied the uniqueness of the recovery motion of the pull condition. Although the forward moment temporarily increased, it was compensated quickly. The other conditions and factors indicated qualitative similarity of the recovery motion among the different conditions. This study demonstrates that the recovery motion after tripping is robust against an increase in forward moment, regardless of the method used to increase the forward moment. The investigation of reaction motion pattern enables validation of the recovery motion and falling posture estimation. Such fall simulations will facilitate the development of a method of fall prevention and mitigation.

Is polypharmacy a risk factor for aspiration pneumonia in older adults? A case-control study.

INTRODUCTION: The incidence of aspiration pneumonia and the number of medicines prescribed increase with older age. Many medicines pose a risk for aspiration pneumonia, especially those that decrease swallowing function. Older adults with polypharmacy often receive a combination of these medicines. This study aimed to clarify whether polypharmacy is a risk factor for aspiration pneumonia. METHODS: Older adults aged ≥ 65 years receiving oral medicines were included in this case-control study. Patients hospitalized for pneumonia served as the case group, and other age-matched hospitalized patients served as the control group. Patient data were collected retrospectively, and logistic regression analysis was performed using items that showed significant differences in the univariate analysis as explanatory variables. RESULTS: Logistic regression analysis revealed that the number of medicines was not a risk factor for aspiration pneumonia; however, it was associated with the Functional Oral Intake Scale score, male sex, body mass index, and number of comorbidities. CONCLUSION: Although polypharmacy is often defined only by the number of medicines, it is not a risk factor for aspiration pneumonia. A detailed comparison of prescription medicines between the pneumonia and non-pneumonia groups is necessary.

Relationship between gait stability indices and gait parameters comprising joint angles based on walking data from 288 people.

Stability during walking is essential because falling accidents may lead to severe injuries. In this study, we calculated the margin of stability (MoS) and the maximum Lyapunov exponent (λs), which are two major stability indices for walking, using a gait database representing 300 healthy people. Previously, the relationships between these indices and other gait parameters, including joint angles, have not been investigated in such a large subject pool. Therefore, we determined the relationships between these stability indices and the gait parameters by calculating correlation coefficients and performing multiple regression analysis. The results indicated that MoS is dominated by walking speed in the forward direction and associated with various joint angles in the lateral direction. Conversely, no relationships were identified between λs and the gait parameters. Although both MoS and λs are considered as measures of gait stability, they are independent. The results of this study suggest that MoS and λs represent different aspects of gait motion.

Metabolic and ventilatory changes during postural change from the supine position to the reclining position in bedridden older patients.

The prevention of pneumonia in bedridden older patients is important, and its recurrence in these patients is a relevant issue. Patients who are bedridden and inactive, and have dysphagia are considered to be at risk for pneumonia. Efforts to reduce the bedridden state and low activity may be necessary to reduce the risk of developing pneumonia in bedridden older patients. This study aimed to clarify the effects of postural change from the supine position to the reclining position on metabolic and ventilatory parameters and on safety in bedridden older patients. Using a breath gas analyzer and other tools, we assessed the following 3 positions: lying on the back (supine), resting in the Fowler position (Fowler), and resting in an 80° recline wheelchair (80°). Measurements were oxygen uptake, carbon dioxide output, gas exchange ratio, tidal volume (VT), minute volume, respiratory rate, inspiratory time, expiratory time, total respiratory time, mean inspiratory flow, metabolic equivalents, end-expiratory oxygen, and end-expiratory carbon dioxide as well as various vital signs. The study analysis included 19 bedridden participants. The change in oxygen uptake driven by changing the posture from the supine position to the Fowler position was as small as 10.8 mL/minute. VT significantly increased from the supine position (398.4 ±â€…111.2 mL) to the Fowler position (426.9 ±â€…106.8 mL) (P  = .037) and then showed a decreasing trend in the 80° position (416.8 ±â€…92.5 mL). For bedridden older patients, sitting in a wheelchair is a very low-impact physical activity, similar to that in normal people. The VT of bedridden older patients was maximal in the Fowler position, and the ventilatory volume did not increase with an increasing reclining angle, unlike that in normal people. These findings suggest that appropriate reclining postures in clinical situations can promote an increase in the ventilatory rate in bedridden older patients.

Young's moduli of subcutaneous tissues and muscles under different loads at the gluteal region calculated using ultrasonography.

[Purpose] Young's modulus distributions for subcutaneous and muscle tissues in a large sample of healthy individuals, based on ultrasonography and compression testing, remains uninvestigated till date. This study aimed to separately estimate the hardness of subcutaneous tissues and muscles in the human gluteal region under a range of loads in terms of mean Young's moduli and associated distributions. [Participants and Methods] Data of 21 males aged 20-22 years were acquired using synchronous compression testing and ultrasonography. Stress-strain curves comprised the loads applied (stress) were plotted against ultrasonographic changes in subcutaneous/muscle tissue thickness (strain). Young's moduli were calculated as slopes of approximation curves fitted to highly linear regions of the stress-strain curves. [Results] Young's moduli (mean ± standard deviation) for gluteal subcutaneous and muscle tissues were estimated as: 26.1 ± 19.0 kPa, 1-N load; 2,199.1 ± 1,354.8 kPa, 30-N load; and 62.2 ± 10.3 kPa, 5-N load; 440.4 ± 80.0 kPa, 30-N load, respectively. No correlation between any pair of these measures reached statistical significance. [Conclusion] Young's moduli were successfully measured for subcutaneous and muscle tissues in a large participant sample using ultrasonography and compression testing. Our results may serve as reference data when assessing tissue hardness by palpation.

Change in ground reaction force parameters according to the frailty level of older women in the Timed Up and Go test.

As older people become frail, they tend to fall more easily. Moreover, women have a higher rate of falls than men. However, effective strategies to avoid elderly women falling are lacking. The Timed Up and Go test is a well-known indicator of falling tendency. This study clarifies the motor elements related to the Timed Up and Go test according to the degree of weakness in older outpatients to specify exercise intervention to improve weakness and prevent falls. Participants were 145 female outpatients who visited the Locomo-Frail outpatient clinic, classified into three groups (robust, prefrail, and frail, according to the definition of the Japanese Cardiovascular Health Study. Vertical ground reaction force parameters were measured for all participants when they stood up from a chair, walking speed, and the Timed Up and Go test. Results showed that walking speed is related to the Timed Up and Go test in the robust group; balance ability is related to the Timed Up and Go test in the prefrail group; and instantaneous force is related to the Timed Up and Go test in the frail group. These results suggest that weakness can be improved by performing exercise interventions of balance and instantaneous force elements in the prefrail and frail groups, respectively.

Multiple Spatial Spectral Components of Static Skin Deformation for Predicting Macroscopic Roughness Perception.

A previous study suggested a relationship between the spatial spectrum of finger pad skin deformation and perception of macroscopic roughness features. This study tested a new hypothesis that macroscopic roughness perception is the result of a weighted linear combination of multiple spatial spectral components of skin deformation. Experiments were conducted by capturing close-up images of finger pad deformation while the pads were pushed onto specimens with macroscopic features. Additionally, the roughness perceptions of these specimens were collected using a magnitude estimation method. The combination of spectral components predicted the roughness perception more accurately than any single spectral component. This suggests that roughness perception is mediated by multiple Gabor filter-like neural systems with different spatial periods, such as visual perception.

Lower limb muscle quality and phase angle contribute to the reduced walking speed among older adults.

AIM: This cross-sectional study aimed to determine the predictors of a walking speed <1 m/s. Factors associated with the health of muscle cells, including the phase angle analyzed using bioimpedance analysis, answers to the mini-nutritional assessment-short form, albumin levels, leg muscle quality and vitamin D levels, were assessed. METHODS: The study participants were outpatients from the Locomotor Frailty Outpatient Clinic which was established at our center in 2016 (231 women, 76.5 ± 7.6 years; 137 men, 78.0 ± 6.3 years). Participants were classified into two groups, with 1 m/s walking speed as the cutoff value. Binominal logistic regression analysis was performed with walking speed as the dependent variable, and age, leg muscle quality, mini-nutritional assessment-short form answers, albumin levels, vitamin D levels and the phase angle as explanatory variables. Leg muscle quality was defined as the mean value of both lower limbs' isometric knee extensor strength, divided by the mean value of both lower limbs' muscle mass through bioimpedance analysis. RESULTS: The explanatory variables associated with decreased walking speed among women were leg muscle quality (P = 0.004, odds ratio: 0.57) and phase angle (P = 0.017, odds ratio: 0.42). Men were also more likely to have leg muscle quality (P = 0.004, odds ratio: 0.43). CONCLUSIONS: Leg muscle quality and the phase angle of lower extremities were independently associated with low walking speeds (<1 m/s) among older outpatients. Geriatr Gerontol Int 2022; 22: 603-609.

Targeted delivery to macrophages and dendritic cells by chemically modified mannose ligand-conjugated siRNA.

Extrahepatic delivery of small interfering RNAs (siRNAs) may have applications in the development of novel therapeutic approaches. However, reports on such approaches are limited, and the scarcity of reports concerning the systemically targeted delivery of siRNAs with effective gene silencing activity presents a challenge. We herein report for the first time the targeted delivery of CD206-targetable chemically modified mannose-siRNA (CMM-siRNA) conjugates to macrophages and dendritic cells (DCs). CMM-siRNA exhibited a strong binding ability to CD206 and selectively delivered contents to CD206-expressing macrophages and DCs. Furthermore, the conjugates demonstrated strong gene silencing ability with long-lasting effects and protein downregulation in CD206-expressing cells in vivo. These findings could broaden the use of siRNA technology, provide additional therapeutic opportunities, and establish a basis for further innovative approaches for the targeted delivery of siRNAs to not only macrophages and DCs but also other cell types.

Linking Temporal Dominance of Sensations for Primary-Sensory and Multi-Sensory Attributes Using Canonical Correlation Analysis.

Sensory responses dynamically change while eating foods. Temporal dominance of sensations (TDS) methods record temporal evolution and have attracted attention in the last decade. ISO 13299 recommends that different levels of attributes are investigated in separate TDS trials. However, only a few studies have attempted to link the dynamics of two different levels of sensory attributes. We propose a method to link the concurrent values of dominance proportions for primary- and multi-sensory attributes using canonical correlation analysis. First, panels categorized several attributes into primary- and multi-sensory attributes. Primary-sensory attributes included sweet, sour, fruity, green, watery, juicy, aromatic, and light. Multi-sensory attributes included refreshing, fresh, pleasurable, rich/deep, ripe, and mild. We applied the TDS methods to strawberries using these two categories of attributes. The obtained canonical correlation model reasonably represented the relationship between the sensations in a reductive manner using five latent variables. The latent variables couple multiple primary- and multi-sensory responses that covary. Hence, the latent variables suggest key components to comprehend food intake experiences. We further compared the model based on the dominance proportions and the time-derivatives of the dominance proportions. We found that the former model was better in terms of the ease of interpreting the canonical variables and the degree to which the canonical variables explain the dominance proportions. Thus, these models help understand and leverage the sensory values of food products.

Surfaces With Finger-Sized Concave Feel Softer.

The judgment of elastic softness is determined not only by mechanical parameters related to hardness, such as the elastic modulus and stiffness, but also by macroscopic surface features. This study experimentally demonstrates that objects with a finger-sized concave with a depth of 1-3 mm feel softer than flat surfaces made of the same materials when they are pushed by a finger. In Experiment 1, participants judged the surfaces of a rigid material with thumb-sized concaves to be softer than the flat and convex surfaces. Experiment 2 used rubbers of various elastic moduli, and the softness of a concave object with a Young's modulus of 0.55 MPa was subjectively equal to that of a flat object with an average Young's modulus of 0.23 MPa. Furthermore, the softness of a convex object was subjectively equal to that of a 1.68 MPa flat object. The contact phenomena between a finger pad and concave or convex objects are different from those between a finger pad and flat objects, and they influence the softness judgment. Such phenomena include the relationship between the pressing force and contact area. These results provide insights into surface design and improve comprehension of the perceptual principles of softness.

Tactile Texture Rendering for Electrostatic Friction Displays: Incorporation of Low-Frequency Friction Model and High-Frequency Textural Model.

Tactile texture presentation on touch panels enhances their usability and realizes immersive user interfaces. This study develops a tactile texture rendering method for electrostatic friction displays. The method combines two rendering models for material textures compared with previous studies which focused on either of these two models. One of these models is a physical model that simulates low-frequency frictional signals depending on the exploratory finger velocities and contact loads. The other is an autoregression-based data-driven model for high-frequency textural friction. For user studies, we compared combining the two models with using only the physical model for the four types of materials. Although the effectiveness varied across the materials, the subjectively judged realism and identification of the materials were improved for the combined condition. The new method combining high-frequency textural information and low-frequency physical model-based friction is expected to provide realistic tactile textures for electrostatic surface tactile displays.

Nucleic Acid Drugs-Current Status, Issues, and Expectations for Exosomes.

Nucleic acid drugs are being developed as novel therapeutic modalities. They have great potential to treat human diseases such as cancers, viral infections, and genetic disorders due to unique characteristics that make it possible to approach undruggable targets using classical small molecule or protein/antibody-based biologics. In this review, I describe the advantages, classification, and clinical status of nucleic acid therapeutics. To date, more than 10 products have been launched, and many products have been tested in clinics. To promote the use of nucleic acid therapeutics such as antibodies, several hurdles need to be surmounted. The most important issue is the delivery of nucleic acids and several other challenges have been reported. Recent advanced delivery platforms are lipid nanoparticles and ligand conjugation approaches. With the progress of exosome biology, exosomes are expected to contribute to the solution of various problems associated with nucleic acid drugs.

Properties of muscle nodules recognized by manual physical therapy practitioners.

[Purpose] The purpose of this study was to describe the properties of muscle nodules (kinkoketsu) recognized by manual physical therapy practitioners. [Participants and Methods] A total of one hundred and thirty-three physical therapists, occupational therapists, judo therapists, and acupuncturists participated in this study. The shape, size, direction, depth, and hardness of muscle nodules, often treated in the buttocks, were investigated through the completion of a questionnaire. [Results] A total of 124 answer sheets were completed; 112 of these described the shape of muscle nodules as ellipsoidal. Of these 112 sheets, 97 effective sheets were analyzed. The results showed that the mean long axis length, short axis length, and thickness of the muscle nodules were 30.9 mm, 16.2 mm, and 9.3 mm, respectively. The most common responses on the long axis direction, depth, and hardness of the muscle nodules were the craniocaudal orientation, the second shallowest layer of 5 divisions, and the eraser level, respectively. [Conclusion] The typical muscle nodule found in the buttocks by manual physical therapy practitioners is roughly the shape of a large almond.

Machine-assisted foot stretching in the elderly: a comparison with self-stretching.

[Purpose] Self-stretching is the traditional at-home stretching method of choice. We developed an automatic foot-stretching machine to perform effective dorsiflexion stretching safely and easily at home. The effects of automatic stretching using our machine and self-stretching were investigated and compared. [Participants and Methods] Twelve healthy elderly people participated in the study. Automatic dorsiflexion static stretching was performed with the right foot, and self-stretching using a towel was performed with the left foot. Before and after each stretching, passive range of motion in dorsiflexion, maximal voluntary contraction strength in plantarflexion, passive resistive torque during passive dorsiflexion, and displacement of the muscle-tendon junction of the medial gastrocnemius muscle were measured. [Results] The range of motion in dorsiflexion had a significantly greater increase after automatic stretching than after self-stretching. The maximum strength in plantarflexion tended to decrease after automatic stretching but did not decrease after self-stretching. The passive resistive torque in both types of stretches decreased in some of the participants but increased in others. The displacement of the muscle-tendon junction of the medial gastrocnemius tended to shorten during automatic stretching as compared with self-stretching. [Conclusion] Foot stretching using a machine is as effective as self-stretching and tends to affect the tendon rather than the muscle.

HumTouch: Localization of Touch on Semi-Conductive Surfaces by Sensing Human Body Antenna Signal.

HumTouch is a touch sensing technology utilizing the environmental electromagnetic wave. The method can be realized using conductive and semi-conductive materials by simply attaching electrodes to the object's surface. In this study, we compared three methods for localizing a touch on 20×16cm2 and 40×36cm2 papers, on which four or eight electrodes were attached to record the voltages leaked from the human fingertip. The number and positions of the electrodes and the data processing of the voltages differed according to the localization methods. By constructing a kernel regression analysis model between the electrode outputs and the actual physical locations, the touched locations were estimated. Each of the three methods was tested via leave-one-out cross validation. Out of the three methods discussed, two exhibited superior performances in terms of the estimation errors. Of these two methods, one simply uses the voltages recorded by the four electrodes attached on the middle of paper edges as inputs to the regression system. The other uses differential outputs of electrode pairs as the inputs. The smallest mean location errors were 0.31 cm on 20×16cm2 paper and 0.27 cm on 40×36cm2 paper, which are smaller than the size of a fingertip.

Principal motion analysis of manual stretching techniques for the ankle joints.

[Purpose] Physical therapists frequently perform manual stretching of the ankle joints. Manual stretching procedures are challenging to define because they involve multidirectional joint motions and external forces. Therefore, in this paper, we propose a method for quantitatively and statistically analyzing the manual foot stretching techniques used by physical therapists. [Participants and Methods] The participants were four physical therapists, and three patients who have a spastic foot. We investigated the manual foot stretching techniques employed by the physical therapists using a three-dimensional analysis system and an instrumented brace with force sensors. Principal motion analysis was applied to the obtained data, and principal motions were determined. [Results] The first principal motion was the application of force for the dorsiflexion of the foot; second, the pushing/pulling of the heel; third, the eversion/inversion of the entire foot; and fourth, the eversion/inversion of the forefoot. Furthermore, the manual stretching techniques varied among the physical therapists, even for the same patient, and some techniques occurred only between particular pairs. [Conclusion] This study demonstrated the effectiveness of the principal motion analysis for the statistical assessment of manual stretching techniques and clarifying differences in stretching technique among physical therapists.

Measurement of Shear Strain Field in a Soft Material Using a Sensor System Consisting of Distributed Piezoelectric Polymer Film.

Measurement of the internal stress and strain distributions within soft materials is necessary in the field of skin contact safety. However, conventional interactive force sensors cannot efficiently obtain or estimate these distributions. Herein, a shear strain sensor system consisting of distributed built-in piezoelectric polyvinylidene fluoride (PVDF) polymer films was developed to measure the internal shear strain field of a soft material. A shear strain sensing model was mathematically established, based on the piezoelectricity and mechanical behavior of a bending cantilever beam, to explain the sensing principle. An experiment in three-dimensional measurement of the shear strain distribution within an artificial skin was designed and conducted to assess the sensitivity of the sensing model. This sensor system could visualize the shear strain field and was sensitive to different contact conditions. The measurement results agreed well with the results of numerical simulation of the substrate, based on contact mechanics. The proposed sensor system was confirmed to provide a new sensing method for the field of shape analysis. The sensor system can be applied to develop sufficiently sensitive electronic skin and can significantly contribute to skin damage analysis and skin contact safety assessment.

Safety considerations for forward falls.

OBJECTIVE: Forward falls are among the most frequent causes of upper extremity fractures. This study investigated the safety considerations to prevent wrist injuries during bimanual forward falls. METHODS: A biomechanical model was developed with two separated arms to facilitate investigation of asymmetrical contact and predict the impact force applied to each hand separately. To validate the developed model, a series of fall experiments were conducted in which one hand collided with a hard surface, while the other collided with a soft surface. RESULTS: The results show that the impact force applied to each hand is independent of the other. Using these results and our model, the safety aspects of human forward falls were analyzed with a view to preventing injuries. Specifically, we sought to determine the safe range of surface stiffness and damping to ensure that the occurrence of forward falls does not lead to trauma. CONCLUSION: The results of this study can be applied in the design of compliant flooring to ensure the safety of people in environments with potential fall hazards. From a robotics viewpoint, the results are applicable in the design of compliant flooring for shared workplaces, where robots collaborate with people and collisions between humans and robots may cause falls.