Development of a wheeled walker braking device using the four-bar mechanism.

The elderly population in many countries has been rising rapidly, and falls are a serious event many elderly people experience. Assistive equipment is actively used to reduce falls among elderly people. Popular types of assistive equipment include canes, electric wheelchairs, and wheeled walkers. Wheeled walkers support the body of elderly people, making their gait comfortable as they age or recover from injuries. Wheeled walkers may be equipped with hand brakes; however, frail older people may experience difficulty using such hand brakes, as they require force to operate. Thus, in the present study, a braking method using a wire connected to a user's belt or clothes was designed and implemented; if the tension of the wire connecting the safety device and the user exceeds a critical value, the wheeled walker brakes, which can prevent the rapid motion of walkers. Two feasibility tests of the wheeled walker with the braking device were conducted: one with 10 healthy adults in their 20s and the other with 10 elderly people over 65 years of age; the tests measured the braking time and speed control using a speed measuring device. The results of the first and second feasibility tests demonstrated that the average braking time of participants was 50.3 ms and 50.7 ms, respectively. All participants in the feasibility tests succeeded in the speed control test. Thus, based on the results, the braking device on the wheeled walker worked properly.

A novel one arm motorized walker for hemiplegic stroke survivors: a feasibility study.

BACKGROUND: A hemiplegic stroke survivor with a moderate to severe gait disturbance may have difficulty walking using a one-arm walker. This study aimed to test the safety and feasibility of a prototype one-arm motorized walker that uses a power-driven device to provide gait assistance to hemiplegic stroke survivors with moderate to severe gait disturbances. METHODS: A one-arm motorized walker with a power-driven device was developed and tested with respect to 10 distinct variables, including weight, degrees of freedom, handle, handle substitution function, two-sided use function, variable handle height, redirecting function, electric moving parts through the handle control, brake function using the handle control, folding chairs, and design stability. Its safety and feasibility were tested in 19 hemiplegic stroke individuals using the Likert scale and a simple interview. RESULTS: The walker consists of a frame platform including a handle, electric motor for driving, one wheel for driving, two wheels for turning, unlocking sensor, driving button, and turning buttons. The walker is programmed so that a touch sensor in the handle can unlock the locking system. Furthermore, it is programmed so that a user can propel it by pushing the handle downward or pressing a button and can control directions for turning right or left by pressing buttons. Safety and performance testing was achieved for 10 separate variables, and a Likert scale score of 3.5 of 5 was recorded. CONCLUSION: This walker's novel design was developed for hemiplegic stroke survivors with moderate to severe gait disturbances. Our findings indicate that the walker is both safe and feasible for providing walking assistance to hemiplegic stroke survivors and establish the potential advantages of the one-arm motorized walker.

A novel hinged ankle foot orthosis for gait performance in chronic hemiplegic stroke survivors: a feasibility study.

Stroke survivors with gait disturbances may use ankle foot orthoses (AFOs). However, most AFOs come in one-piece styles, which make it difficult for spasticity-affected stroke survivors to don. AFOs are also limited since they do not properly prevent ankle joint for foot drop by itself. Therefore, the present study developed a novel hinged AFO by adding a locking device to a hinged joint. We then tested its feasibility in 9 hemiplegic stroke survivors by investigating temporal-spatial gait parameters using the GAITRite in the following 3 conditions: no AFO, traditional AFO, and novel hinged AFO. There was no significant difference in spatiotemporal gait parameters among the different conditions. There were greater decreases in gait velocity, cadence, step length, and stride length in the novel hinged AFO group than in the no AFO and traditional AFO groups. This novel hinged AFO was developed to prevent foot drop. However, the AFO did not show significant differences in gait parameters because it consists of metal with extra weight and volume. Functionally, it prevented foot drop. It also improved convenience by its releasable design. Thus, further studies are needed to develop an AFO that improves gait and is convenient to use for hemiplegic stroke survivors.

Comparison of trunk electromyographic muscle activity depends on sitting postures.

BACKGROUND: Different postural positions can be characterized by the activation and relative contributions of different postural muscles, and may variously contribute to the recovery from or worsening of chronic lower back pain. OBJECTIVE: The present study aimed to investigates trunk muscle activities in four types of seated postures: cross-legged, long, side, and W-shaped. METHODS: Eight healthy adults participated in the study. Trunk muscle activities of the external oblique (EO), rectus abdominis (RA), latissimus dorsi (LD), and erector spinae (ES) muscles in each of the sitting postures including cross-legged, long, side, and W-shaped were collected utilizing surface electromyography (sEMG). The mean sEMG signals in each of the sitting postures were used for statistical comparisons. RESULTS: There were no significant differences in electromyographic muscle activity of EO, RA, LD, and ES in the four postures (p > 0.05). However, in the W-shape sitting posture, the left LD showed the greatest electromyographic muscle activity, followed by the right LD and left EO, respectively. The right and left LD in the long sitting posture and left ES in the side sitting posture showed greater electromyographic muscle activity than that of other muscles. CONCLUSION: Based on the results, trunk muscle activity did not significantly differ between the four types of sitting postures. However, our study is limited by its experimental method and sample size. Thus, in the Future, further study will be needed.

Fatigue of human dentin by cyclic loading and during oral biofilm challenge.

Fatigue caused by the cyclic loads of mastication and acid attack caused by the excretion of oral biofilms are two of the most critical challenges to the success of dental restorations and their clinical service life. The objective of this investigation was to evaluate the fatigue strength of human dentin when exposed to a simultaneous challenge of cyclic loading and acidic attack from oral bacteria. Rectangular beams of coronal dentin were obtained from third molars and subjected to cyclic flexural loading while exposed to an in-vitro microcosm biofilm model. Two different cariogenic protocols were considered and results were compared with those for control samples evaluated at neutral pH. According to the fatigue life distributions, dentin exposed to the biofilm model with 2.0% sucrose supplements pulsed twice per day caused a significant reduction in the fatigue strength (p < 0.001) with respect to 0.2% sucrose supplements pulsed once a day, and the control environment (without biofilm). The endurance limit after biofilm exposure was 20 MPa, which is 60% lower than that of the control environment without biofilm (50 MPa). Biofilm attack of dentin increases the likelihood of restored tooth failures by fatigue and after only modest periods of exposure. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1978-1985, 2017.

Influence of light touch using the fingertips on postural stability of poststroke patients.

[Purpose] The purpose of this study was to investigate the influence of fingertip light touch on the postural control in poststroke patients. [Subjects] In the study, the subjects were recruited through a rehabilitation hospital, and 21 patients were screened from among 30 volunteers. [Methods] The subjects participated in an experiment that measured postural sway during the static standing posture without light touch and postural sway during the static standing posture with light touch as follows: visual information not blocked without light touch, visual information blocked without light touch, visual information blocked with light touch using fingertips, and visual information not blocked with light touch using fingertips. The measurements were performed using a force platform. The variables measured by the force platform included sway velocities of the COP in the anterior and posterior directions and, medial and lateral directions and sway velocity moments. [Results] In the results of the study, there were significant differences between the state without light touch and state with light touch in terms of the postural sway velocity and velocity moment under all conditions. The rate of decease of the sway velocity and moment velocity under the eyes closed condition were higher compared with those under the eyes open condition. [Conclusion] Through this study, we confirmed the influence of fingertip light touch on the decrease in postural sway. The results show that active light touch may be supplemental means of improving postural sway in stroke patients.

Dependences of the electrical properties on the diameter and the doping concentration of the Si nanowire field effect transistors with a Schottky metal-semiconductor contact.

A compact model of the current-voltage (I-V) characteristics for the Si nanowire field effect transistor (FET) taking into account dependence of the analytical electrical properties on the diameter and the concentration of the Si nanowire of the FETs with a Schottky metal-semiconductor contact has been proposed. I-V characteristics of the nanowire FETs were analytically calculated by using a quantum drift-diffusion current transport model taking into account an equivalent circuit together with the quantum effect of the Si nanowires and a Schottky model at Schottky barriers. The material parameters dependent on different diameters and concentrations of the Si nanowire were numerically estimated from the physical properties of the Si nanowire. The threshold voltage, the mobility, and the doping density of the Si nanowire and the Schottky barrier height at a metal-Si nanowire heterointerface in the nanowire FET were estimated by using the theoretical model.

Donor-strain-derived immature dendritic cell pre-treatment induced hyporesponsiveness against allogeneic antigens.

The maturation of antigen-presenting dendritic cells (DCs) serves as an important determinant for the regulation of immunity, and overall immune response. We hypothesized that a reduced immune response to donor alloantigens and improved allograft survival could be induced by pre-treating recipients with bone-marrow-derived donor-strain fixed immature DCs (FIDCs). Donor-strain-derived mature and immature DCs were fixed before grafting to ensure that they possessed a stable immunogenic phenotype. The fixed mature DCs effectively induced allogeneic T-cell proliferation in recipients, whereas FIDCs were unable to elicit an allogeneic T-cell response. T cells that had previously been exposed to FIDCs maintained naïve phenotypes and were unable to extensively divide after injection into lethally irradiated donor-strain mice. The pre-treatment of recipients with donor-strain FIDCs markedly prolonged the survival of islet as well as skin allografts. However, T-cell hyporesponsiveness induced by FIDC injection was abrogated by the depletion of CD4(+) CD25(+) T cells. Consequently, FIDC-induced T-cell hyporesponsiveness could reflect anergy rather than specific deletion. Our findings suggest that FIDCs of donor strain could be used to induce long-term graft survival.

Role of NKT cells in allogeneic islet graft survival.

Although NKT cells expressing CD1d-reactive TCR exerted protective role in autoimmune diseases, the regulatory function of CD1d-dependent NKT cells in alloimmune responses has not been investigated thoroughly. Here, we demonstrated the regulatory effects of NKT cells using a pancreas islet transplantation model. CD40/CD154 blocking induced long-term graft survival in most B6 recipients, but B6.CD1d(-/-) recipients showed co-stimulation blockade-resistant rejection. Adoptive transfer of NKT cells into B6.CD1d(-/-) restored tolerizing capacity of co-stimulatory blockade. Activation of NKT cells was effective for the prolongation of graft survival and up-regulated membrane-bound TGF-beta expression transiently on their cell surface. The activated CD1d-dependent NKT cells inhibited alloantigen-driven cell proliferation through cell contacts and the beneficial effect of CD154 blocking for allograft survival was related to TGF-beta pathway. Thus, we can conclude that NKT cells are essential for the stable allograft survival and the regulatory function is dependent on, at least in part, TGF-beta engagement.

Distinctive role of donor strain immature dendritic cells in the creation of allograft tolerance.

Dendritic cells (DCs) are pivotal antigen-presenting cells and serve a unique role in initiating immunity. To test the hypothesis that pre-immunization of recipient with certain DC subsets of donor origin can influence graft outcome, we have studied the effects of immunization with allogeneic CD4(+)CD8(-)CD11c(+) dendritic cell (CD4(+)DC) and CD4(-)CD8(+)CD11c(+) dendritic cell (CD8(+)DC) on the allograft response. Although both immature CD4(+)DC and CD8(+)DC subsets from DBA/2 were able to prime naive allogeneic C57BL/6 (B6) T cells in mixed lymphocyte reaction (MLR), CD8(+)DC exerted more vigorous alloimmune responses than CD4(+)DC did. Also, CD4(+)DC-driven allogeneic T cell response was attenuated more significantly by anti-CD154 mAb than CD8(+)DC-driven response. Consistent with the MLR results, combined pre-treatment with CD4(+)DC, but not CD8(+)DC, plus anti-CD154 mAb produced donor strain-specific long-term graft survival and induced tolerance while treatment with CD8(+)DC plus anti-CD154 mAb created minimal prolongation of allograft survival in a pancreas islet transplant model (DBA/2-->B6). The beneficial effects exerted by CD4(+)DC and anti-CD154 mAb pre-treatment were correlated with T(h)1 to T(h)2 immune deviation and with the amplified donor-specific suppressive capacity by recipient CD4(+)CD25(+) T cells. These findings highlight the capacity of CD4(+)DC to modulate alloimmune responses, and suggest therapeutic approaches for the induction of donor-specific tolerance.

Calcium accumulation on activated carbon deteriorates synthetic organic chemicals adsorption.

The accumulation of calcium on biological activated carbon (BAC) and their effects on adsorption of synthetic organic chemicals (SOCs) were studied using BAC, which have been operated for 5 (BAC5.0) and 3.5 (BAC3.5) years in a pilot-scale water purification plant, and granular activated carbon (GAC) preloaded with fulvic acid and/or calcium. The major inorganic material accumulated on BAC was calcium. The amounts of calcium on BAC5.0 and BAC3.5 were 36.6 and 29.7 mg g(-1), respectively. Seventy-one percent of calcium existed as calcium carbonate in both BACs. BAC5.0 had higher amount of accumulated calcium than BAC3.5 even though both BACs have already exhausted for NOM in the influent in 1-year operation, suggesting that calcium carbonate gradually accumulated on BAC even after the 3.5 years of operation. The isotherms of GAC preloaded with fulvic acid and/or calcium clearly indicated that the calcium accumulation on GAC reduced adsorption capacity for simazine. The conclusion also confirmed by significant recovery of adsorption capacity of both BACs by acid-washing to remove accumulated calcium from BACs. The difference of adsorption capacity between BAC3.5 and BAC5.0 was caused not only by the difference of adsorbed NOM but also the difference in the amount of accumulated calcium.