Cytotoxicity and mechanical properties of the prosthetic liner / 中国康复理论与实践

@# Objective To investigate the current status of cytotoxicity and mechanical properties of the prosthetic liner on the market in China.Methods Six kinds of liner were collected, namely domestic 6 mm thick foam liner (A), domestic 5 mm thick EVA foam liner (B), German 5 mm thick EVA foam liner (C), Germany 12 mm thick PE foam liner (D), Iceland 3 mm thick silicone liner (E) and Germany 4 mm thick gel liner (F). Microscopic observation and thiazole blue colorimetry were used to detect the cytotoxicity. The content of small organic molecules was determined by the consumption of potassium permanganate. The tensile strength, elongation at break (%), and 100% tensile strength of the prosthetic liner were tested by material mechanics testing machine. The hardness was tested using the Shore hardness tester oo type.Results The cytotoxicity was grade 2 for prosthetic liners A, B, C and D, and was grade 0 for E and F. The redox substance content of prosthetic liners A、B、C exceeded 150 mg/kg. Except the prosthetic liner C, the hardness of the other products were all ≤ 70 HA. Except prosthetic liner D, the tensile strengths were > 1 MPa, breaking elongations were > 120.0%, 100% tensile strengths were > 0.9 MPa for other products.Conclusion Due to materials and production processes, the cytotoxicity and mechanical properties of the six samples are quite different.

The efficacy of median nerve electrical stimulation in rehabilitating post-stroke cognitive impairment and its mechanism / 中华物理医学与康复杂志

Objective:To test the effectiveness of electrical stimulation of the median nerve (MNES) for relieving post-stroke cognitive impairment (PSCI) and explore the possible mechanism.Methods:Thirty patients with PSCI were randomly divided into a routine treatment group (the control group) and an MNES group, each of 15. Both groups were given routine rehabilitation treatment, including cognitive rehabilitation training, medications and acupuncture. The MNES group additionally received 30 minutes of MNES on their right hands every day, five times a week for six weeks. One electrode was positioned over the median nerve 2cm up from the rasceta of the right wrist. The other was on the muscles of the thenar eminence. Forty seconds of stimulation were applied with intervals of 20 seconds, for 30 min daily. Before and after 3 and 6 weeks of treatment, both groups were evaluated using the mini-mental state examination (MMSE), the Montreal cognitive assessment (MoCA), the modified Barthel index (MBI) and the Fugl-Meyer assessment (FMA). In another 15 patients oxyhemoglobin levels in the brain before and during the MNES were observed using near-infrared spectroscopy.Results:After 3 weeks of treatment, a significant improvement was observed in the average MMSE, FMA and MBI scores of both groups, and the average MoCA score of the observation group. Three weeks later, the average MMSE, FMA, MBI and MoCA scores of both groups had improved significantly compared with before the treatment, with the average MMSE and MoCA improvements in the MNES group significantly greater than the control group′s averages. After 6 weeks of treatment the significant improvements persisted in both groups. Both group′s average FMA scores had also improved significantly, as had the average MBI score of the control group. After 6 weeks of treatment, the observation group′s average time orientation, location orientation, language instant memory, attention, calculation and short-term memory in MMSE had all improved significantly along with visual space capacity, executive capacity, attention, language, orientation and memory in MoCA. The spectroscopic results showed significantly improved oxyhemoglobin concentration in the bilateral frontal lobes after the MNES.Conclusions:Electrical stimulation of the median nerve can help to improve cognition after a stroke. It increases oxyhemoglobin concentration in the bilateral frontal lobes.

Effects of pressure on soft tissue stress distribution and muscle oxygenation in sacrum area for persons with spinal cord injury / 生物医学工程学杂志

Sacrum area is the high-risk area for pressure ulcer to persons with spinal cord injury. A finite element model of the soft tissue in the sacrum area was established to analyze the stress distribution in the soft tissue with the human body lying down. In addition, the muscle oxygenation in the sacrum area was assessed by near-infrared spectroscopy (NIRS) before and after loading pressures. The results showed that the stress was mainly localized in the muscle layer and the stress in the bone-tissue interface was the maximal. When the loading reached 10kPa, the maximal stress in the muscle layer was 15kPa. The muscle oxygenation parameters changed significantly with the applied pressure and returned to normal level after the loading.

Synthetic effect analysis of heart rate variability and blood pressure variability on driving mental fatigue / 生物医学工程学杂志

Driving mental fatigue is a substantial problem and threatens people's health and life. This investigation was made to evaluate the driving mental fatigue based on power spectral analysis of heart rate variability (HRV) and blood pressure variability (BPV) synthetically. Twenty health male subjects (28.8 +/- 4.3 years) were required to perform the simulated driving for 90 min. The frequency domain indices of HRV such as low frequency (0.04-0.15 Hz, LF), high frequency (0.15-0.4 Hz, HF), LF/HF together with the indices of hemodynamics such as blood pressure (BP) and heart rate (HR) of the subjects were calculated and anlyzed after the simulated driving. The results showed that sympathetic activity of the subjects enhanced after the simulated driving while parasympathetic activities decreased. The sympathovagal balance was also improved. Remarkable linear correlations were observed between all the corresponding indices of HRV and BPV (P<0.05). The findings suggested that the evaluation of autonomic activities by means of multi-variable synthetic effect analysis is scientific and objective.

The effect of magnitopuncture stimulation on HRV during simulated driving under vibration conditions / 生物医学工程学杂志

The purpose of this study was to assess the effect of magnitopuncture stimuli for reducing driver mental stress and fatigue using power spectral analysis of the heart rate variability (HRV) and subjective evaluation. The experiments were divided into A-group and B-group. In both groups the subjects performed the simulator for 90 minutes under a vibration conditions with an erect sitting posture in a silent environment, and magnitopuncture was put on the acupoints when performing the task for one hour in A-group. In this study HRV exhibited a significant difference between the two groups after the simulating task (P < 0.05). A conclusion that magnitopuncture stimuli can reduce the driver mental stress and fatigue effectively was drawn.