Effects of infant care posture and weight on static postural balance.

BACKGROUND: Studies investigating postural balance during various infant care postures have not been reported yet. OBJECTIVE: The aim of this study was to measure static postural balance when holding an infant dummy in-arms and carrying an infant dummy on back according to different infant dummy weights. METHODS: Sixteen healthy young subjects participated in a balance test. Infant dummies with weights of 4.6 kg (1-month) and 9.8 kg (12-month) were used in this study. All subjects were asked to naturally stand on a force platform in two infant care postures (holding an infant in-arms and carrying an infant on one's back). Center of pressure (COP) was measured from the force platform. Quantitative variables were derived from the COP. Two-way repeated measure analysis of variance (ANOVA) was performed to determine main effects of infant care postures, infant weight, and their interactions on COP variables. RESULTS: Back carrying a 12-month infant dummy had the greatest amplitude in all COP variables. Back carrying posture showed significantly greater mean distance and peak power, faster mean velocity, and wider COP area compared to holding posture (P< 0.05). There were significant weight effects of most COP variables mainly in AP direction (P< 0.01). CONCLUSIONS: Our results could contribute to the prevention of musculoskeletal diseases or prevention of fall due to various infant care activities by developing an assisting device to improve postural balance.

Comparison of resting tremor at the upper limb joints between patients with Parkinson's disease and scans without evidence of dopaminergic deficit.

BACKGROUND: A representative symptom of Parkinson's disease (PD) is resting tremor. The clinical manifestation of scans without evidence of dopaminergic deficit (SWEDD) is similar to it of PD, though the phenomenology of SWEDD is not well known. OBJECTIVE: In the present study, the resting tremor of 9 SWEDD patients was quantitatively compared with that of 11 PD patients. METHODS: Four 3-axis gyro sensors were attached on the index finger, thumb, dorsum of the hand, and arm of the more tremulous side. Root mean square (RMS) angular speed and angular displacement as well as irregularity of angular speed and displacement were derived from the sensor data. RESULTS: Although disease duration and Hoehn and Yahr stages were comparable, SWEDD patients exhibited different tremor features from PD patients. Significantly faster RMS angular speed and greater RMS angular displacement (p< 0.05) were observed in PD patients than in SWEDD patients. The irregularity of angular displacement of pitch direction at the dorsum of the hand was greater in SWEDD patients than in PD patients (p< 0.05). CONCLUSION: These results indicate that quantitative indices obtained from resting tremor task could be important biomarkers for identifying potential patients with SWEDD among patients diagnosed with PD.

Protective effects of Populus tomentiglandulosa against cognitive impairment by regulating oxidative stress in an amyloid beta25-35-induced Alzheimer's disease mouse model.

BACKGROUND/OBJECTIVES: Alzheimer's disease (AD) is one of the most representative neurodegenerative disease mainly caused by the excessive production of amyloid beta (Aß). Several studies on the antioxidant activity and protective effects of Populus tomentiglandulosa (PT) against cerebral ischemia-induced neuronal damage have been reported. Based on this background, the present study investigated the protective effects of PT against cognitive impairment in AD. MATERIALS/METHODS: We orally administered PT (50 and 100 mg/kg/day) for 14 days in an Aß25-35-induced mouse model and conducted behavioral experiments to test cognitive ability. In addition, we evaluated the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and measured the production of lipid peroxide, nitric oxide (NO), and reactive oxygen species (ROS) in tissues. RESULTS: PT treatment improved the space perceptive ability in the T-maze test, object cognitive ability in the novel object recognition test, and spatial learning/long-term memory in the Morris water-maze test. Moreover, the levels of AST and ALT were not significantly different among the groups, indicating that PT did not show liver toxicity. Furthermore, administration of PT significantly inhibited the production of lipid peroxide, NO, and ROS in the brain, liver, and kidney, suggesting that PT protected against oxidative stress. CONCLUSIONS: Our study demonstrated that administration of PT improved Aß25-35-induced cognitive impairment by regulating oxidative stress. Therefore, we propose that PT could be used as a natural agent for AD improvement.

Age-related differences in the quantitative analysis of the finger tapping task.

BACKGROUND: Quantitative measures of the finger tapping task is important for objective assessment of bradykinesia. However, age-related changes in quantitative measures are still unclear. OBJECTIVE: The aim of this study was to quantitatively investigate age-related group differences in finger tapping performance. METHODS: Eighty-three healthy normal subjects with age ranging from aged 20 to 89 years participated in this study. All subjects were instructed to tap their index finger and thumbs as rapidly as possible and with as large amplitude as possible. Angular velocity of the finger tapping movement was measured using a gyrosensor. Quantitative variables include root mean squared (RMS) angular velocity, RMS angular displacement, peak power and peak frequency derived from angular velocity signals. RESULTS: Significant age-related differences were observed in RMS angular velocity, peak power and peak frequency (P< 0.001). Specifically, the oldest age group had the slowest average speed, the lowest peak power and peak frequency. These results indicate deterioration in finger speed, intensity of the main movement component and tapping frequency due to aging. CONCLUSIONS: The results suggest that the quantitative variables should be adjusted for age when clinicians assess Parkinsonian bradykinesia. The results contribute to the development of an accurate and quantitative assessment tool for bradykinesia.

Analysis of maximum joint moment during infant lifting-up motion.

BACKGROUND: Infant care activities can induce musculoskeletal disease. However, little is known about the biomechanical joint load during lifting-up of an infant. OBJECTIVE: The aim of this study was to investigate normalized maximum moment during lifting-up of infant dummies weighing 4.6 kg, 7.6 kg, and 9.8 kg. METHODS: Six healthy young subjects participated in our study. All subjects performed lifting-up activities of dummies to shoulder height with their feet apart and natural postures in their comfortable speed. Three-dimensional reflective marker trajectories and ground reaction forces were used as input to calculate joint moments using a full body musculoskeletal model. Joint moments were normalized by each subject's body mass. Friedman's test was performed to compare mean differences of normalized joint moments for lifting up three dummy weights. RESULTS: Lumbar joint had the greatest normalized joint moment. Lumbar and hip extension moments were significantly increased with dummy weight (P< 0.05). In contrast, knee extension and ankle plantarflexion moment were not significantly affected by dummy weight (P> 0.05). CONCLUSIONS: These results indicate that the lumbar joint plays the most important role in infant lifting-up motion and that the load of lumbar and hip joint should be reduced when lifting a heavier infant. These results could contribute to the development of an effective lifting strategy and an assisting device for lifting an infant.

Protective effects of krill oil on high fat diet-induced cognitive impairment by regulation of oxidative stress.

Consumption of high fat diet (HFD) increases risk of cognitive impairment and memory deficit by elevation of oxidative stress in the brain. In this study, we investigated the protective effects of krill oil (KO) against HFD-induced cognitive impairment in mice. The mice were fed with HFD for 10 weeks, and then KO was orally administered at doses of 100, 200, or 500 mg/kg/d for 4 weeks. To evaluate the cognitive abilities, we carried out the behavior tests, such as T-maze, novel object recognition test, and Morris water maze test. The HFD-induced cognitive impairment mice showed impairments in both spatial memory and novel object cognitive abilities. However, administration of KO at doses of 100, 200, or 500 mg/kg/d improved spatial memory ability and novel object cognition by increase of the exploration of new route and novel object. In addition, KO-administered group improved learning and memory abilities, showing shorter latency to reach hidden platform compared with control group. Furthermore, levels of reactive oxygen species (ROS), lipid peroxidation, and nitric oxide (NO) were significantly elevated by consumption of HFD, indicating that consumption of HFD induces oxidative stress in the brain. However, administration of KO attenuated oxidative stress by decrease of the ROS levels, lipid peroxidation, and NO. This study suggests that KO improves HFD-induced cognitive impairment by attenuation of oxidative stress in the brain. Therefore, KO may play as a promising agent in treatment and prevention of HFD-induced cognitive impairment.

Quantitative measures of postural tremor at the upper limb joints in patients with essential tremor.

BACKGROUND: It is important to quantitatively assess tremor for accurate diagnosis and evaluation of the response to interventions in patients with essential tremor (ET). OBJECTIVE: The purpose of this study was to investigate the relationship between quantitative measures of postural tremor and clinical rating scale in patients with ET. METHODS: 18 ET patients performed a postural tremor task that required them to hold their arms outstretched parallel to the floor while wearing a gyro sensor based measurement system. The time domain variables were derived from the sensor signals. Additionally, the frequency domain variables were derived from the power spectrum of the angular velocity signal. Spearman correlation analysis was employed in the relationship between the variables and clinical score. RESULTS: The RMS angular velocity of roll and yaw directions at the hand joint were strongly correlated with the clinical rating scale (r= 0.7, p< 0.01). Similarly, the peak power of roll and yaw directions at the hand joint were moderately correlated with the clinical rating scale (r= 0.61 and r= 0.67, p< 0.01). In contrast, no significant correlation coefficients were observed in the peak frequency (p> 0.05). CONCLUSION: These results indicate that hand tremor of roll and yaw directions are more associated with assessment of severity of ET compared to other joints. This study suggests that quantitative measurements of postural tremor should be considered as tremor directionality as well as attachment location.

Comparison of gait patterns in elderly fallers and non-fallers.

Gait is associated with an important risk factor of falls in the elderly. It is important to find differences of quantitative gait variables between fallers and non-fallers. The aim of this study was to investigate gait patterns in elderly fallers and non-fallers. Thirty-eight fallers and 38 non-fallers of similar age and height participated in this study. Subjects walked across the GaitRite walkway at self-selected comfortable speeds. Spatio-temporal gait variables were measured to characterize gait patterns. Kinetic variables were derived from normalized vertical ground reaction force (GRF). Independent t-tests were performed to compare the fallers with the non-fallers. The fallers walked more slowly with shorter steps and more variable step times than the non-fallers (p< 0.05). The fallers showed a longer stance phase with increased double-limb support than the non-fallers (p< 0.05). The times to reach maximal weight acceptance and mid-stance of the fallers were significantly longer than those of the non-fallers (p< 0.05). These results suggest that spatio-temporal variables and GRF variables would be useful for distinguishing prospective fallers from non-fallers among the elderly.

The Association between 10-Year Atherosclerotic Cardiovascular Diseases Risk Score Calculated Using 2013 American College of Cardiology/American Heart Association Guidelines and Serum 25-Hydroxyvitamin D Level among Aged 40-79 Years in Korea: The Sixth Korea National Health and Nutrition Examination Surveys.

BACKGROUND: We examined the relationship between 10-year predicted atherosclerosis cardiovascular disease (ASCVD) risk score and 25-hydroxyvitamin D in Koreans aged 40-79 years. METHODS: A population-based, cross-sectional design was used from data based on the Korea National Health and Nutrition Examination Survey 2014. RESULTS: A total of 1,134 healthy Koreans aged 40-79 years were included. A positive relationship between serum 25-hydroxyvitamin D level and ASCVD score was shown in women (ß=0.015) after adjusting for central obesity, physical activity, and supplement intake. The chances of being in the moderate to high risk (risk group, ASCVD score ≥5%) with vitamin D sufficiency (serum 25-hydroxyvitamin D ≥20 ng/mL) was 1.267-fold (95% confidence interval, 1.039-1.595) greater than the chance of being included in the group with vitamin D deficiency (serum 25-hydroxyvitamin D <20 ng/mL) after adjustments in women. CONCLUSION: Our research indicated a significantly positive association between 25-hydroxyvitamin D and ASCVD score. Further detailed studies to evaluate this correlation are needed.

Differences in activities of the lower extremity muscles with and without heel contact during stair ascent by young women wearing high-heeled shoes.

BACKGROUND: The purpose of this study was to identify any differences in the activity patterns of lower extremity muscles with and without heel contact during stair ascent by women in their twenties wearing high-heeled shoes. METHODS: Twenty healthy female subjects wearing high-heeled shoes walked up a step with a height of 20 cm with and without heel contact, during which the activities of the vastus medialis oblique, vastus lateralis, and gastrocnemius were recorded using surface electromyography. RESULTS: During stair ascent the activities of the vastus lateralis and vastus medialis oblique were significantly higher and that of the gastrocnemius significantly lower with high-heel contact than without high-heel contact. CONCLUSION: We suggest that young women wearing high-heeled shoes should step up with heel contact on the stair surface during stair ascent to activate the quadriceps muscle.