Analysis of Postural Instability in the Upright Position on Narrow Platforms and the Interactions with Postural Constraints.

BACKGROUND: Loss of balance is a considerable risk factor for workers while using ladders, because they are required to maintain static postural balance on platforms of a restricted size. This study observed center of mass (CoM) and center of pressure (CoP) behaviors and evaluated the effects of the platform depth (anterior-posterior length) and working postures. METHODS: Eleven male participants stood on four platforms with depths ranging from 6 to 15 cm and maintained their positions for 60 s while performing or not performing other tasks (object holding, upward viewing, or both simultaneously). The kinematics were analyzed on the sagittal plane based on the inverse pendulum model. RESULTS: The absolute moving range for the CoP-CoM linearly increased with the decreasing platform depth, and the working postures affected the slopes of the linear fits. The relative range of CoP-CoM displacement on narrow platforms was highly correlated with the subjective sense of instability. CONCLUSIONS: Monitoring the CoP is effective for a better understanding and evaluation of static postural balance. This study's findings contribute to improving the design of work equipment through the use of wider platforms that are robust against the effects of working postures.

A novel approach to bi-objective optimization of touch-screen installation position for minimizing physical workload and increasing screen visibility.

The aim of this study was to propose a new method for optimizing the touch-screen installation position in order to minimize the physical workload and increase screen visibility. Ten students participated in this study. The participants utilized a touch screen at different installation heights (50, 65, and 80% of stature), tilt angles (0°, 45°, and 90° from the horizontal plane), and having different button sizes (a square with a side of 10, 20, and 30 mm). The joint angles, when using a touch screen, were measured to calculate the joint torque ratios (JTRs). Subjective screen visibility were also determined. The optimal installation position was determined by solving a bi-objective optimization problem consisting of two objective functions. The Pareto optimal solutions for the two objectives showed a range of 1124-1251 mm and 44.4-67.9°. The proposed method determined the optimal installation position of the touch screens.

Wound healing after revascularization for critical limb ischemia.

BACKGROUND: Wound healing is one of the most important endpoints after revascularization for critical limb ischemia. The purpose of this study was to evaluate the risk factors for wound healing after revascularization for critical limb ischemia (CLI). METHODS: A retrospective study was conducted at a single university hospital, and data were collected retrospectively between January 2005 and September 2016. All admitted patients who were diagnosed with CLI and underwent revascularization for the first time were enrolled. The risk factors for wound healing were analyzed. RESULTS: The risk factors for wound healing were analyzed in 153 patients. The cumulative rate of wound healing at 12 months after revascularization was 79%. The independent risk factors for wound healing were non-ambulatory status (hazard ratio, 1.95; 95% CI [1.22-3.21], P=0.004), and wound, ischemia and foot infection (WIfI) stage 4 (hazard ratio, 1.89; 95% CI [1.25-2.91], P=0.002). CONCLUSIONS: In our study, non-ambulatory status and WIfI stage 4 were independent risk factors for wound healing after revascularization. WIfI criteria well reflected the prognosis of patients with CLI in wound healing, as well as limb salvage.

Proresolving Lipid Mediators Resolvin D1 and Protectin D1 Isomer Attenuate Neointimal Hyperplasia in the Rat Carotid Artery Balloon Injury Model.

BACKGROUND: Specialized proresolving mediators from ω-3 polyunsaturated fatty acid may control resolution of inflammation. We evaluated the influence of two specialized proresolving mediators, resolvin D1 (RvD1) and protectin D1 isomer (PD1 iso) on neointimal hyperplasia after balloon injury. MATERIALS AND METHODS: Sprague Dawley male rats at 12-14 wk of age were injured as a model of balloon angioplasty. Then, 1 µg/rat of RvD1 or PD1 iso was administered intravenously via the tail vein immediately and 2 d after angioplasty. The proliferation of injured artery and the infiltration of leukocytes, monocytes, and macrophages at 3 d after injury were evaluated by immunostaining. The activity of the inflammatory transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) in the injured artery at 3 d after injury was evaluated using an enzyme-linked immuno sorbent assay kit. The proliferation of the neointima was evaluated by calculating the ratio of the neointimal and medial areas using specimens at 14 d after injury. RESULTS: RvD1 and PD1 iso attenuated proliferation of medial cells (P < 0.05) and infiltration of leukocytes (P < 0.05) and monocytes/macrophages (P < 0.01). Although both RvD1 and PD1 iso mitigated NFκB activity (P < 0.01), RvD1 attenuated this activity more strongly (P < 0.01). RvD1 decreased neointimal hyperplasia by 37.3% (P < 0.01), whereas PD1 iso decreased neointimal hyperplasia by 31.8% (P < 0.05) (RvD1 versus PD1 iso: P = 0.51). CONCLUSIONS: RvD1 and PD1 iso reduced the activity of inflammatory transcription factor NFκB within the injured artery and attenuated inflammatory cell infiltration, leading to a reduction in early inflammation and subsequent neointimal hyperplasia.

The relationship between medical expenses and the severity of peripheral arterial disease in Japan.

The main objective is to examine whether the severity of peripheral arterial disease (PAD) affects the expenses and hospital stay of the patients who undergo bypass surgery below the inguinal ligament for PAD. Eighty consecutive patients who underwent infrainguinal bypass surgery for PAD between January 2012 and December 2014 were included in the study. Patients were divided into groups according to their critical limb ischemia (CLI) symptoms and the Wound, Ischemia, and Foot Infection (WIfI) classification. As endpoints, we assessed the duration of postoperative hospital stay and expenses during hospitalization. CLI was a significant factor for longer hospital stay and increased medical expenses (p = 0.009 and p = 0.001). In the patients with CLI, significant factors for longer hospital stay and increased medical expenses were (1) history of distal bypass (p = 0.33 and p = 0.003, respectively) and stage 4 local lower limb status in WIfI classification (p = 0.0007 and p = 0.053). PAD severity was associated with prolonged postoperative hospital stay and increased medical expenses. The presence or absence of CLI and its severity according to the WIfI classification correlated with medical expenses and hospital stay duration between the milder and severe groups.

Evaluation of physical workload affected by mass and center of mass of head-mounted display.

A head-mounted display (HMD) with inappropriate mass and center of mass (COM) increases the physical workload of HMD users. The aim of this study was to investigate the effects of mass and COM of HMD on physical workload. Twelve subjects participated in this study. The mass and posteroanterior COM position were 0.8, 1.2, or 1.6 kg and -7.0, 0.0, or 7.0 cm, respectively. The subjects gazed at the target objects in four test postures: the neutral, look-up, body-bending, and look-down postures. The normalized joint torques for the neck and the lumbar region were calculated based on the measured segment angles. The results showed that the neck joint torque was significantly affected by mass and COM and it increased as the HMD mass increased for all test postures. The COM position that minimized the neck joint torque varied depending on the test postures, and the recommended ranges of COM were identified.

False reduction of an inguinal hernia treated by Kugel patch repair via an anterior approach.

BACKGROUND: Reduction en masse of inguinal hernia is a rare condition following manual reduction of an unrecognized incarcerated inguinal hernia. The preoperative diagnosis and surgical treatment via an inguinal approach has been considered difficult. CASE PRESENTATION: A 59-year-old man with lower abdominal pain was presented to our hospital. He was diagnosed reduction en masse of an inguinal hernia based on his CT findings which showed the presence a pre-peritoneal hernia sac containing the small bowel. An emergency operation via an anterior approach was performed and we found a hernial sac containing an incarcerated small bowel at the cranial and internal sides of the internal inguinal ring. Opening of the hernial sac revealed necrosis of the incarcerated small bowel and bowel resection was performed. Kugel patch was inserted into the pre-peritoneal space and the patient made an uneventful recovery. CONCLUSION: When it is accurately diagnosed, reduction en masse of an inguinal hernia can be treated with direct Kugel repair via an anterior approach.

Evaluation of multiple muscle loads through multi-objective optimization with prediction of subjective satisfaction level: illustration by an application to handrail position for standing.

Proposed here is an evaluation of multiple muscle loads and a procedure for determining optimum solutions to ergonomic design problems. The simultaneous muscle load evaluation is formulated as a multi-objective optimization problem, and optimum solutions are obtained for each participant. In addition, one optimum solution for all participants, which is defined as the compromise solution, is also obtained. Moreover, the proposed method provides both objective and subjective information to support the decision making of designers. The proposed method was applied to the problem of designing the handrail position for the sit-to-stand movement. The height and distance of the handrails were the design variables, and surface electromyograms of four muscles were measured. The optimization results suggest that the proposed evaluation represents the impressions of participants more completely than an independent use of muscle loads. In addition, the compromise solution is determined, and the benefits of the proposed method are examined.

Perceived discomfort functions based on joint moment for various joint motion directions of the upper limb.

The aim of the present study was to formulate the relationship between the perceived discomfort and the joint moment ratio for twelve joint motion directions of the upper limb by considering the between-subject variability, and to investigate the effect of joint motion direction. Three approximation models (i.e., linear, exponential, and logistic function models) were compared in terms of the accuracy of predicting the perceived discomfort, and the logistic function was selected because its average error was lowest. The concept of L-R fuzzy number was used to consider the individual variability of perceived discomfort, and a simplified distribution of perceived discomfort was represented. Cluster analysis showed that the twelve discomfort functions formed two clusters: one for elbow flexion and a second for the remaining joint motions. The data show that elbow flexion is more sensitive than other joint motions to increases in the joint moment ratio.

The Feasibility of Central Pancreatectomy for Blunt Pancreatic Trauma: A Comparative Study of Central and Distal Pancreatectomy.

BACKGROUND/AIMS: Central pancreatectomy (CP) is an alternative technique of distal pancreatectomy (DP) for focal pancreatic tumors; however, the feasibility of CP for pancreatic trauma has not been adequately assessed. METHODOLOGY: Patients who underwent CP (n = 8) or DP (n = 8) for pancreatic duct injuries following blunt trauma were reviewed. Patient demographics, status of pancreatic duct injuries, and perioperative outcomes were compared between procedures. RESULTS: Pancreatic duct injuries occurred at the neck of the pancreas in 63% patients (10/16). Patient demographics and perioperative outcomes were comparable between the CP and DP groups. Polytrauma was found in 38% patients in both groups. No differences were found between patients treated with CP and DP in overall blood loss (median: 1025 mL vs 1800 mL, P = 0.418) and surgical duration (median: 284 min vs 188 mm, P = 0.172). The incidence of pancreas-related complications was comparable between groups (CP: 50% vs. DP: 38%, P = 0.614. CONCLUSIONS: Blunt pancreatic duct injuries tend to occur at the pancreatic neck, leaving the body and tail of the pancreas intact. CP is feasible for blunt pancreatic trauma in hemodynamically stable patients.

Risk factors for frequent work-related burn and cut injuries and low back pain among commercial kitchen workers in Japan.

This study investigated risk factors for frequent work-related burn and cut injuries and low back pain (LBP) among kitchen workers including personal, work-related and environmental factors. Subjects were 991 kitchen workers in 103 schools, 17 hospitals and nursing homes, and 6 restaurants in central Japan. A cross-sectional survey was carried out using a structured self-administered questionnaire. Logistic regression models were used to examine associations between frequent injuries/LBP and risk factors. The effective response rate was 75.1% (n=744), the mean age was 40.7 (SD 11.7) and 77.2% were female. Burn injury was associated with a smaller kitchen (OR 1.94; 95%CI, 1.13-3.33), and gas kitchens rather than electric kitchens (OR 2.30; 95%CI, 1.17-4.52). LBP was associated with female gender (OR 2.46; 95%CI, 1.37-4.43), high body height (>160 cm) (OR 2.03; 95%CI, 1.22-3.36), and large number of meals produced per person (≥ 150 meals) (OR 1.83; 95%CI, 1.12-3.00). The results of this study suggest that securing adequate work space and introducing electric kitchen systems may reduce the risk to kitchen workers, as well as the importance of adequate height of cooking equipment and selecting an appropriate volume of meals to produce per person to prevent LBP in kitchen workers.

Proanthocyanidin-rich grape seed extract reduces leg swelling in healthy women during prolonged sitting.

BACKGROUND: Leg swelling is a modern-day affliction of sedentary working women. The aim of this study was to evaluate the effectiveness of the intake of grape seed extract (GSE) on leg swelling in healthy Japanese women while sitting. RESULTS: Single intake trials and 14 day intake trials were held in a double-blind, placebo-controlled, crossover clinical study. A prolonged sedentary position was maintained for 6 h after GSE or placebo administration. Leg volume distension, increase in body extracellular fluid, and leg water were significantly suppressed in the GSE groups. CONCLUSION: The intake of GSE is a contributing factor in the inhibition of leg swelling in healthy women during prolonged sitting.

Work form affects maximum oxygen uptake for one year in workers.

Our previous study suggested that the work form is related to the maximum oxygen uptake (VO(2)max). Therefore, we test the hypothesis by a longitudinal study that, besides these lifestyle-related factors, the work form increases VO(2)max among workers. Seven hundred and ninety nine males aged 37.1 ± 10.6 and 395 females aged 37.7 ± 10.5 (range: 20 to 59 yr old), who participated in The Total Health Promotion Plan (THP) at their respective workplaces twice in one year from 1997 to 1998, were selected. Data on VO(2)max were analyzed for age, systolic blood pressure (SBP), body mass index (BMI), work form (sedentary, standing, and ambulatory), exercise, and smoking. Age and the baseline variables for BMI and for VO(2)max showed significant negative relationships with a change in VO(2)max in males and females. Further, a change in the BMI showed a significant negative relationship with a change of VO(2)max in males. However, exercise habit and an ambulatory work form showed significant positive relationships with a change of VO(2)max in males. It was suggested that after adjusting for other factors in males, an ambulatory work form may be associated with an increase in VO(2)max in one year.

Evaluation of subjective thermal strain in different kitchen working environments using subjective judgment scales.

To elucidate the subjective thermal strain of workers in kitchen working environments, we performed a cross-sectional study involving 991 workers in 126 kitchen facilities in Japan, using a self-reporting questionnaire survey and subjective judgment scales (SJS). The ambient temperature, mean radiant temperature (MRT), and wet-bulb globe temperature (WBGT) index were measured in 10 kitchen facilities of the 126 kitchens. The association of SJS with the types of kitchen was estimated by multiple logistic regression models. Of the 991 kitchen workers, 809 (81%) responded to the questionnaire survey. Compared with the electric kitchens, the proportion of workers who perceived the room temperature as hot to very hot was significantly higher, and the ambient temperature, MRT, and WBGT were significantly higher in the gas kitchens. Compared with the electric kitchens, workers in gas kitchens had a more than fivefold (males) and tenfold (females) higher SJS adjusted for confounding factors (male odds ratio (OR), 5.13; 95% confidence interval (CI), 1.65-15.9; and female OR, 10.9; 95%CI, 3.89-30.5). Although SJS was affected by some confounding factors, our results suggest that workers in gas kitchens might be exposed to a higher heat strains than those in electric kitchens.

Effects of heating appliances with different energy efficiencies on associations among work environments, physiological responses, and subjective evaluation of workload.

To clarify the association between heat stress, physiological responses and subjective workload evaluations in kitchens using an induction heating stove (IH stove) or gas stove. The study design was an experimental trial involving 12 young men. The trial measured ambient dry-bulb temperature, globe temperature, wet-bulb globe temperature (WBGT) and relative humidity; the subjects' weight, heart rate, blood pressure, oxygen uptake, amount of activity, body temperature, subjective awareness of heat and workload before and after mock cooking for 30 min. The IH stove insignificantly increased heat indicators in the work environment and workers showed lower oxygen uptake, skin temperature, subjective awareness of heat and workload after heat exposure. Both physiological load and subjective awareness of heat and workload were slight in kitchens using the IH stove, which provided a better work environment.

Effect of nursing assistance tools on preventing musculoskeletal pain among staff in schools for disabled children.

Objective is to clarify whether nursing assistance tools (a mat with attached handles, a pair of trousers with knee pads and a waist holding belt) prevent musculoskeletal pain, such as low back pain and upper arm pain, and depression, and improve the burden on the lower back and upper arm among staff in schools for disabled children. This study design was a non-randomized intervention trial. The subjects were 41 staff in two schools for disabled children in Japan. Nursing assistance tools were used with the intervention group to help with their nursing activities. We investigated the one-month prevalence of low back pain and the degree of burden on the lower back using a questionnaire at the baseline and at the end point 4 to 6 months later. The prevalence of low back pain did not change significantly in either group. In the intervention group, the prevalence of upper arm pain decreased from 47.6% at the baseline to 23.8% at the end point (p=0.063). The percentage of participants with a high level of burden on the lower back from excretory nursing activity decreased from 57.1% at the baseline to 33.3% at the end point (p=0.063) in the intervention group. These results suggest that nursing assistance tools may prevent upper arm pain and improve the burden on the lower back among staff in schools for disabled children; however, these tools did not significantly prevent low back pain and depression.

Job stressors and job stress among teachers engaged in nursing activity.

Teachers and staff members engaged in nursing activity experience more stress than other workers. However, it is unknown whether teachers engaged in nursing activity in schools for handicapped children experience even greater stress. This study evaluated job stressors and job stress among such teachers using a cross-sectional study design. The subjects were all 1,461 teachers from all 19 prefectural schools for handicapped children in Shizuoka Prefecture, Japan. We used a brief job stress questionnaire for the survey and 831 teachers completed the questionnaire. Job stressors among teachers engaged in nursing activity were compared with those among teachers not engaged in nursing activity. Job stress among such teachers was estimated by the score for total health risk, and was compared with the score in the Japanese general population. Male and female teachers engaged in nursing activity had a significantly higher level of job stressors for physical work load and job control compared with those not engaged in nursing activity. The scores for total health risk among male and female teachers engaged in nursing activity were 102 points and 98 points, respectively. These scores were not markedly above 100 points which is the mean score in the Japanese general population.

Physical work load affects the maximum oxygen uptake.

PURPOSE: Maximum oxygen uptake (VO2max) is known to be influenced by life-style factors, such as exercise and smoking. We aimed to further test the hypothesis that, besides these, work form also contributes to increase VO2max among workers. METHOD: Three thousand six hundred and forty eight male workers with age 38.3 +/- 12.1 and 1,575 female workers with age 35.6 +/- 11.1, ranging from 20-year old to 69-year old, who participated in Total Health Promotion Plan at workplaces in Fukui Prefecture in 1998 were selected. Data on VO2max were analyzed for age, systolic blood pressure (SBP), body mass index (BMI), work form (sedentary, standing or ambulatory), exercise, and smoking. RESULTS: Multiple regression analysis showed that work form ("standing", "ambulatory"), and exercise habits might increase VO2max while BMI, age, and SBP might decrease VO2max in male participants. Exercise habits were suggested to increase VO2max while BMI, SBP, and age might decrease VO2max in females. In females smoking, was suggested to increase VO2max. CONCLUSION: After adjusting for age, BMI, SBP, exercise, and smoking, it was suggested that the physical work load, represented by the work form, may contribute to increases in VO2max in males. Implications of smoking among females with respect to VO2max is discussed.

Prevalence of and risk factors for low back pain among staffs in schools for physically and mentally handicapped children.

The objective of this study is to clarify the prevalence of and risk factors for low back pain (LBP) in schools for physically and mentally handicapped children. This study design is a cross-sectional study. The subjects included were 1,869 staff members from 19 prefectural schools for children in Shizuoka Prefecture, Japan, which included schools for the blind, deaf-mutes, physically handicapped, and mentally retarded children. A total of 975 subjects completed two postal questionnaires which included morbidity, demographic factors, nursing activity, and psychosocial factors. The answer rate was 52%. The one-month prevalence of LBP was 45%. According to the classification of nursing activity, assistance in movement 1.67 (95% CI 1.27-2.14), excretory function 1.45 (1.11-1.88), and feeding 1.44 (1.10-1.90) showed significant increases in the odds ratio. The adjusted odds ratio significantly increased by 2.35 (1.78-3.11) in the group with depression symptoms as well as in the group with job stressors such as quantitative, qualitative, and physical work loads, job control, utilization of technique, interpersonal conflicts, and degree of satisfaction with their work/home life.

Estimation of trunk muscle parameters for a biomechanical model by age, height and weight.

To establish more accurate equations for estimating the moment arm length and cross-sectional area of the erector spinae and rectus abdominis muscles, the effects of height, weight and age on those muscles were analyzed by using a high-order polynomial equation. Data on the moment arm length and cross-sectional area at L3/4 were obtained from MRI images of 152 males and 98 females. The statistical model used in this study has any combination of up to third-order independent variables for age, height and weight. The effective independent variables were selected by the forward step method of multiple regression analyses. The results of multiple regression analyses showed that the polynomial equations for the moment arm length of erector spinae in both genders, and that for the rectus abdominis in males, contained all three variables of age, height and weight. That for the moment arm length of female rectus abdominis contained the variables of weight and age. The multiple correlation coefficients of the erector spinae and rectus abdominis were 0.355 and 0.650 for males, 0.364 and 0.411 for females, respectively. The equations for the cross-sectional area of the erector spinae in both genders, as well as that for male rectus abdominis contained only one variable (weight). The multiple correlation coefficients of the cross-sectional area of the erector spinae were 0.576 for males and 0.469 for females. The cross-sectional area of the female rectus abdominis had no effective variables.