Identification of characteristics of foot position and angle during swing phase in fallers using principal component analysis.

Identifying the characteristics of fallers is important for preventing falls because such events may reduce quality of life. It has been reported that several variables related to foot positions and angles during gait (e.g., sagittal foot angle and minimum toe clearance) differ between fallers and non-fallers. However, examining such representative discrete variables may not be sufficient to detect crucial information, which may be contained in the large portions of unanalyzed data. Therefore, we aimed to identify the comprehensive characteristics of foot position and angle during the swing phase of gait in non-fallers and fallers using principal component analysis (PCA). Thirty non-fallers and 30 fallers were recruited for this study. We performed PCA to reduce the dimensions of foot positions and angles during the swing phase and obtained principal component scores (PCSs) for each principal component vector (PCV), which were then compared between groups. The results revealed that the PCS of PCV3 in fallers was significantly larger than that in non-fallers (p = 0.003, Cohen's d = 0.80). We reconstructed waveforms of foot positions and angles during the swing phase using PCV3 and our main findings can be summarized as follows. Compared to non-fallers, fallers have a 1) low average foot position in the z-axis (i.e., height) during the initial swing phase 2) small average foot angle in the x-axis (i.e., rotation in the sagittal plane), during the initial swing phase, and 3) large variability in foot position in the y-axis (i.e., anterior/posterior position) during the initial swing phase. We can conclude that these are characteristics of gait related to fallers. Therefore, our findings may be beneficial for evaluating fall risk during gait using a device such as a shoe- or insole-embedded inertial measurement unit.

Effect of gait protocols and postoperative shoes on off-loading of forefoot in preoperative patients for forefoot disorders.

OBJECTIVES: The purpose of this study was to clarify the effect of gait protocols and postoperative shoes on forefoot load in preoperative patients for forefoot disorders and compare footwear comfort between different types of postoperative shoes. METHODS: Fourteen subjects scheduled to undergo forefoot surgeries were recruited. The maximum force under the forefoot region was measured during 10 m straight walking in two gait patterns with six different shoe types. Visual analogue scale (VAS) scores for footwear comfort, subjective lower thigh pain, and electrical activities of lower thigh muscles were also evaluated. RESULTS: The body weight-normalized maximum force under the forefoot region significantly decreased in step-to gait compared to normal gait regardless of the shoe types used. Under the same gait condition, no significant difference was observed in the forefoot off-loading effect between the different shoe types used. Significantly worse VAS scores, significantly higher tibialis anterior muscle activities, and complaints of lower thigh pain were demonstrated in the gait with the reverse camber shoe. CONCLUSIONS: Gait protocol of step-to gait had more forefoot off-loading effect than postoperative shoes. The forefoot off-loading effect did not differ among the postoperative shoes, suggesting that postoperative shoes can be selected with an emphasis on footwear comfort.

A 'Giving way' captured during walking by gyroscopes and plantar force sensors.

'Giving way' is a rapid inversion of the rear part of the foot, which does not result in an acute lateral ankle sprain. It is a specific event for patients with chronic ankle instability (CAI). This report described a 'giving way' in an 18-year-old female with CAI, which was biomechanically captured during walking on the flat surface. Shoes with unstable heel having a hemisphere rubber on the sole of the heel were used to provoke 'giving way'. To the authors' knowledge, this is the first report describing the kinetics of 'giving way' during walking. The event of 'giving way' was captured by an Inertial Motor Unit located on the dorsum of the foot and an insole-shaped plantar force measurement device. 'Giving way' provided distinctive data on both kinds of devices. Gyroscope data showed a rapid increase of inversion/plantarflexion/internal rotation (maximum levels: 204/280/346 degree/s) and following eversion/dorsiflexion/external rotation (maximum levels: 509/798/797 degree/s) of the foot segment at 350 ms - 492 ms after the heel strike. Plantar force data demonstrated the rapid decrease and subsequent recovery of the regional force on the head of 1st metatarsal head, suggesting a rapid inversion followed by the foot's defensive eversion. Although the maximum angular velocity of the inversion was smaller and the duration of inversion phase of 'giving way' was shorter than in previous reports, the characteristics of the following eversion phase of 'giving way' were consistent with earlier reports. The eversion must be a more specific phase than the inversion in the kinematics of 'giving way'.

Stability of d-luciferin for bioluminescence to detect gene expression in freely moving mice for long durations.

Circadian disturbance of clock gene expression is a risk factor for diseases such as obesity, cancer, and sleep disorders. To study these diseases, it is necessary to monitor and analyze the expression rhythm of clock genes in the whole body for a long duration. The bioluminescent reporter enzyme firefly luciferase and its substrate d-luciferin have been used to generate optical signals from tissues in vivo with high sensitivity. However, little information is known about the stability of d-luciferin to detect gene expression in living animals for a long duration. In the present study, we examined the stability of a luciferin solution over 21 days. l-Luciferin, which is synthesized using racemization of d-luciferin, was at high concentrations after 21 days. In addition, we showed that bioluminescence of Period1 (Per1) expression in the liver was significantly decreased compared with the day 1 solution, although locomotor activity rhythm was not affected. These results showed that d-luciferin should be applied to the mouse within, at most, 7 days to detect bioluminescence of Per1 gene expression rhythm in vivo.

Double recording system of Period1 gene expression rhythm in the olfactory bulb and liver in freely moving mouse.

Clock genes express circadian rhythms in most organs. These rhythms are organized throughout the whole body, regulated by the suprachiasmatic nucleus (SCN) in the brain. Disturbance of these clock gene expression rhythms is a risk factor for diseases such as obesity and cancer. To understand the mechanism of regulating clock gene expression rhythms in vivo, multiple real time recording systems are required. In the present study, we developed a double recording system of Period1 expression rhythm in peripheral tissue (liver) and the brain. In peripheral tissue, quantification of gene expression in a steadily moving target was achieved by using a photomultiplier tube (PMT) attached to a tissue contact optical sensor (TCS). Using this technique, we were able to analyze circadian rhythms of clock gene expression over a prolonged period in the liver and olfactory bub (OB) of the brain. The present double recording system has no effect on behavioral activity or rhythm. Our novel system thus successfully quantifies clock gene expression in deep areas of the body in freely moving mice for a period sufficient to analyze circadian dynamics. In addition, our double recording system can be widely applied to many areas of biomedical research, as well as applications beyond medicine.

Mouse period1 gene expression recording from olfactory bulb under free moving conditions with a portable optic fibre device.

Because the disruption of circadian clock gene is a risk factor in many diseases such as obesity and cancer, it is important to monitor and analyzed the expression of the rhythm of the clock gene throughout the body over a long period of time. Although we previously reported on a new gene expression analysis system tracking a target position on the body surface of freely moving mice, the experimental apparatus required a large space. We have therefore developed an in vivo recording system using a portable photomultiplier tube (PMT) system attached to an optical fibre. Directly connecting the target area with the device, we could easily measure the photon counts in a very small space. However, little information is known about the characteristics of optical fibres when exposed to twisting/looping in association with a moving mouse and the effect of the surface of optical fibre. In the present study, we report on the characteristics of optical fibres to detect gene expression rhythm in freely moving mice. Using this portable optical device directly connected with a target area, we were able to measure the circadian rhythm of clock gene expression over a prolonged period in freely moving mice in a small space.

Evaluation of plantar pressures in people with hallux valgus using principal component analysis.

BACKGROUND: Foot deformities are serious problems in the elderly as they increase the risk of falling. OBJECTIVE: This study aimed to examine the relationship between foot plantar pressure during gait and hallux valgus (HV). METHODS: Foot-pressure data were recorded using an F-scan II system. We analyzed the entire waveform of plantar pressure during gait from 37 healthy adults using principle component analysis (PCA), conducted using a 370 × 357 matrix of time-normalized plantar data of 7 areas during gait (5 gait trials × 2 (both feet) of 37 participants × 51 data points × 7 plantar areas). Two-way (plantar pressure × presence or absence of HV) analyses of variance were conducted on the principal component scores (PCSs) of principal component vectors (PCVs) 1 through 5, each of which exhibited more than 5% variance. RESULTS: The PCA clarified that the 2nd, 3rd, and 5th PCVs (PCV 2, 3, and 5) were related to HV (p< 0.01). These PCVs exhibit a significant interaction between plantar pressure area and HV presence. CONCLUSIONS: The larger plantar pressure of the HV group around the hallux area during walking compared with the non-HV group is a dominant difference in plantar pressure features due to HV.

Comparative analysis on inactivation kinetics of between piezotolerant and piezosensitive mutant strains of Saccharomyces cerevisiae under combinations of high hydrostatic pressure and temperature.

We previously obtained a pressure-tolerant (piezotolerant) and a pressure sensitive (piezosensitive) mutant strain, under ambient temperature, from Saccharomyces cerevisiae strain KA31a. The inactivation kinetics of these mutants were analyzed at 150 to 250MPa with 4 to 40°C. By a multiple regression analysis, the pressure and temperature dependency of the inactivation rate constants k values of both mutants, as well as the parent strain KA31a, were well approximated with high correlation coefficients (0.92 to 0.95). For both mutants, as well as strain KA31a, the lowest k value was shown at a low pressure levels with around ambient temperature. The k value approximately increased with increase in pressure level, and with increase and decrease in temperature. The piezosensitive mutant strain a924E1 showed piezosensitivity at all pressure and temperature levels, compared with the parent strain KA31a. In contrast, the piezotolerant mutant strain a2568D8 showed piezotolerance at 4 to 20°C, but did not show significant piezotolerance at 40°C. These results of the variable influence of temperature on pressure inactivation of these strains would be important for better understanding of piezosensitive and piezotolerant mechanisms, as well as the pressure inactivation mechanism of S. cerevisiae.

Effect of high pressure on the saccharification of starch in the tuberous root of sweet potato (Ipomoea batatas).

We analyzed the effect of high hydrostatic pressure (HHP) treatment on reducing sugar production in the tuberous root of sweet potato (Ipomoea batatas), based on pressure-gelatinization of starch and subsequent saccharification by internal amylases. HHP treatment at up to 600MPa at ambient temperature for 10min did not apparently affect the reducing sugar concentration in tuberous root. However, HHP treatment at 100 to 500MPa and 60°C or 70°C for 10min increased reducing sugar concentration as both the pressure and temperature increased. The reducing sugar concentration after HHP treatment at 500MPa and 70°C for 10min was roughly comparable to that of the thermal treatment control (80°C for 10min under atmospheric pressure). HHP treatment enabled the gelatinization and enzymatic saccharification of starch in the tuberous root of sweet potato, at a lower temperature than required by thermal treatment at atmospheric pressure.

Measuring gait pattern in elderly individuals by using a plantar pressure measurement device.

BACKGROUND: Hip fracture in the elderly is a serious problem, and solutions to prevent falls are needed. OBJECTIVE: This study focused on elucidating data critical to fall prevention by evaluating ambulatory function, and we achieved this by developing a plantar pressure measurement device to determine gait function. METHODS: Our device enables measurement of gait function in the unrestrained state by transmitting wireless data. In this study, we applied the device to field experiments involving 98 subjects (39 healthy individuals, 44 elderly non-fallers, and 15 elderly fallers). Gait features were determined by measuring the pressure values and foot contact patterns used as gait function parameters in previous studies. RESULTS: In particular, decreased peak pressure values were noted at heel strike and toe off during walking in elderly fallers compared with elderly non-fallers. In addition, compared with healthy subjects, elderly fallers also showed extension of the double support phase, and differences in individual gait pattern features were observed between the groups. CONCLUSIONS: Experiments confirmed that our device can be used to obtain the gait features of a diverse group of elderly individuals. Moreover, our device enables objective and quantitative evaluation of gait function and thus may be useful for evaluating gait function in the elderly.

Enzymatic production of γ-aminobutyric acid in soybeans using high hydrostatic pressure and precursor feeding.

The effects were investigated of the glutamic acid (Glu) substrate concentration on the generation and kinetics of γ-aminobutyric acid (GABA) in soybeans treated under high hydrostatic pressure (HHP; 200 MPa for 10 min at 25 °C). The conversion of Glu to GABA decreased with increasing initial Glu concentration in the soybeans. The crude glutamate decarboxylase (GAD) obtained from the HHP-treated soybeans showed substrate inhibition. The GABA production rate in the HHP-treated soybeans fitted the following substrate inhibition kinetic equation: v0=(VmaxS0)/(Km+S0+(S0)2/Ki). The Km value for the HHP-treated soybeans was significantly higher than that of the untreated soybeans. The Km values in this study show the affinity between Glu and GAD, and indicate that the HHP-treated soybeans had lower affinity between Glu and GAD than the untreated soybeans. GAD extracted from the HHP-treated soybeans showed a similar value to that in the HHP-treated soybeans. The intact biochemical system was so damaged in the HHP-treated soybeans that it showed substrate inhibition kinetics similar to that of the extracted GAD. The combination of HHP and precursor feeding proved to be a novel tool that can be used to increase the concentration of a target component.

Low-dose glucocorticoid therapy complements the pituitary-adrenocortical system and reduces anxiety and insomnia in myasthenia gravis patients.

Myasthenia gravis (MG) is an autoimmune disorder generally mediated by antibodies against the acetylcholine receptors of the skeletal muscles. Depending on the disease burden, MG patients may experience chronic dysregulation of both the hormonal stress axis and the immune system, consequently, aggravating the disease itself but also leading to secondary psychopathological abnormalities. A long-term clinical course requires long-term glucocorticoid (GC) therapy, which may change the psychological state by affecting the pituitary-adrenocortical system in MG patients. In this study, we investigated the function of the pituitary-adrenocortical system in MG patients who were treated with prednisolone (PSL) and evaluated their quality of life by using the Medical Outcomes Study 36-item Short-Form Health Survey and the 28-item general health questionnaire (GHQ-28). ACTH and cortisol levels in the plasma of patients who were treated with PSL (PSL[+] group, n = 18) were lower than those in the plasma of patients who were treated without PSL (PSL[-] group, n = 29; P < 0.05 and P < 0.01, respectively). In the PSL(+) group, we confirmed that cortisol levels negatively correlated with daily PSL dosages (P < 0.05). The anxiety and depression scores from the GHQ-28 in the PSL(+) group were lower than those in the PSL(-) group (P < 0.05, respectively). There was no significant correlation between cortisol levels and corticotropin levels in plasma of the PSL(-) group. However, we confirmed that corticotropin levels positively correlated with cortisol levels in plasma (P < 0.01) and negatively correlated with anxiety/insomnia scores from the GHQ-28 (P < 0.05) in the PSL(+) group. In conclusion, low-dose GC treatment complemented the pituitary-adrenocortical system and improved the psychological state in MG patients.

Clinical implication of peripheral CD4+CD25+ regulatory T cells and Th17 cells in myasthenia gravis patients.

Myasthenia gravis (MG) is an autoimmune disorder generally mediated by antibodies against the acetylcholine receptors (AChR) of the skeletal muscles. CD4 T cells help B cells to produce antibodies through their production of cytokines or chemokines. In this study, we evaluated the frequency of regulatory (Treg) and IL-17 producing CD4 T-cell subsets (Th17) in peripheral blood mononuclear cells (PBMCs) of patients with MG. The transcription factor, forkhead transcription factor (Foxp3), is essential for T-cell regulatory function, and the orphan nuclear receptor, RORgammaT, is important in Th17 cell differentiation. In MG patients, Foxp3 mRNA expression in PBMCs was lower than those in healthy subjects (p=0.007), while there was no significant difference of RORgammaT mRNA expression between MG patients and healthy subjects. Glucocorticoid-induced tumour-necrosis-factor receptor-related protein (GITR) is expressed predominantly on CD4(+)CD25(+) Treg cells. We found that the number of GITR(+)CD4(+)CD25(+) T cells in peripheral lymphocytes in MG patients was lower than that in healthy subjects (P<0.01). In addition, there was a significant positive correlation between the change of the frequency of GITR(+)CD4(+)CD25(+) T cells and the changing rate in quantitative myasthenia gravis scores (%) (p=0.03). Furthermore, there was a significant negative correlation between the change of the percentage of GITR(+)CD4(+)CD25(+) T cells (% lymphocytes) and the changing rate of daily PSL doses (%) (P=0.002). The relative RORgammaT levels in PBMCs negatively correlated with the Th1/Th2 ratio in CD4(+) cells in MG patients (p=0.014). In conclusion, our findings suggest that Th17 cells affect the production of autoantibodies through their influence on the Th1- and Th2-cytokine balance in PBMCs of MG patients. On the other hand, Treg cells are suggested to be involved in the clinical condition or severity of MG disease.

Generation of free amino acids and gamma-aminobutyric acid in water-soaked soybean by high-hydrostatic pressure processing.

The effects of high-hydrostatic pressure processing (HPP) on soybean cotyledon as a cellular biological material were investigated from the viewpoints of the cell structure and enzyme reaction system. Damage to cell structure was evaluated by measuring dielectric properties using the Cole-Cole arc, the radius of which decreased as pressure level increased. Results suggested that cell structure was damaged by HPP. The distribution of free amino acids was measured after HPP (200 MPa) of soybean soaked in water or sodium glutamate (Glu) solution. HPP resulted in high accumulation of free amino acids in water-soaked soybean, due to proteolysis. HPP of soybean in Glu solution caused higher accumulation of gamma-aminobutyric acid, suggesting that both proteolysis and specific Glu metabolism were accelerated by HPP. We concluded that HPP partially degraded cell structure and accelerated biochemical reactions by allowing enzyme activities to remain. These events can be considered "high-pressure induced transformation" of soybean.

Clinical implications of the type 1/type 2 balance of helper T cells and P-glycoprotein function in peripheral T lymphocytes of myasthenia gravis patients.

Myasthenia gravis is an autoimmune disorder mediated by antibodies against the acetylcholine receptors of the skeletal muscles. Imbalances between T helper type 1 and type 2 cytokine production play a key role in the induction and development of several autoimmune diseases. Peripheral T helper type 1 and type 2 cells in 50 myasthenia gravis patients were estimated by intracellular cytokines. The percentage of T helper type 1 cells in CD4(+) cells was higher than that of type 2 or type 0 cells (P<0.0001). There was a significant correlation between T helper type 1/type 2 ratio and the P-glycoprotein function on CD3(+) T cells (P=0.008). In the patients treated with prednisolone alone (n=12), there was a significant correlation negatively between the percentage of change in the T helper type 1/type 2 ratio and the reduction rate of quantitative myasthenia gravis scores after 12 months of treatment (P=0.012). In contrast, all of the patients treated with prednisolone and calcineurin inhibitor in combination saw reductions in the scores. Our data suggest that the T helper type 1/type 2 ratio was involved in the disease activity of the patients treated with prednisolone alone. On the other hand, the patients treated with prednisolone and calcineurin inhibitor in combination had their disease condition improved regardless of the T helper type 1 predominance. Therefore, the data suggest that supplemental calcineurin inhibitors are effective for the myasthenia gravis patients treated with prednisolone alone when their T helper balance shifts toward to type 1.

P-glycoprotein function in peripheral T lymphocyte subsets of myasthenia gravis patients: clinical implications and influence of glucocorticoid administration.

Myasthenia gravis (MG) is an autoimmune neuromuscular disorder with a chronic clinical course that requires long-term glucocorticoid (GC) therapy. A drug efflux pump, P-glycoprotein (P-gp), actively transports GC out of target cells, thereby reducing its efficacy. We evaluated the P-gp function of peripheral-blood mononuclear cells in 59 MG patients. P-gp function was estimated from a decrease in fluorescent P-gp substrate Rhodamine 123 and its inhibition by the conformation-sensitive UIC2 monoclonal antibody. P-gp function on CD8(+) T cells in 21 MG patients having experienced GC therapy was higher than that in 19 MG patients having no history of GC therapy (p=0.026). There was a significant correlation between P-gp function in CD3(+) (r=0.55, p=0.014) or CD4(+) (r=0.48, p=0.034) T cells and the total dose of prednisolone for treatment. P-gp function on CD4(+) T cells in MG patients who showed low responses to prednisolone therapy (n=8) was higher than that in patients who showed relatively high responses to prednisolone therapy (n=10) (p=0.045). These results suggest that higher P-glycoprotein activity on CD3(+) or CD4(+) cells necessitated treatment with higher steroid doses in order to achieve a clinical response. The measurement of P-gp function on CD4(+) T cells is useful in the assessment of clinical response to GC therapy.

Suppressive potencies of calcineurin inhibitors against the mitogen-induced blastogenesis of peripheral-blood mononuclear cells of myasthenia gravis patients.

The calcineurin inhibitors, tacrolimus and ciclosporin, are two useful immunosuppressive drugs for the treatment of myasthenia gravis (MG), for patients who have low responses to glucocorticoids. We have studied the suppressive potencies of tacrolimus and ciclosporin on concanavalin A-induced blastogenesis of peripheral-blood mononuclear cells (PBMCs) obtained from 38 MG patients and 26 healthy volunteers. Differences in the IC50 values of the two calcineurin inhibitors between the patients and the healthy subjects were evaluated. The median (range) IC50 values for tacrolimus and ciclosporin on the blastogenesis of PBMCs of MG patients were 0.06 (0.001-100) and 0.41 (0.09-83.0) ng mL(-1), respectively. In contrast, the median (range) IC50 values of tacrolimus and ciclosporin on healthy PBMCs were 0.16 (0.001-0.33) and 5.59 (1.4-31.3), respectively, and thus ciclosporin potencies against PBMCs of MG patients were significantly higher than those against PBMCs of healthy subjects (P < 0.0001). The differences in tacrolimus IC50 values between the patients and healthy subjects were not significant. There was a correlation between ciclosporin IC50 values against the blastogenesis of PBMCs of MG patients and the duration of the disease (r = 0.35, P = 0.049). A significant correlation between the IC50 values of ciclosporin and those of prednisolone against the blastogenesis of PBMCs of MG patients was also observed (r = 0.56, P = 0.003). Furthermore, the ciclosporin IC50 values significantly correlated with the periods of glucocorticoid administration for MG treatment (r = 0.42, P = 0.038). Such correlations were not observed with the tacrolimus IC50 values. These results suggested that glucocorticoid administration had an influence on PBMC response to the suppressive efficacy of ciclosporin in MG.