Mesenchymal stem cells (MSCs) secrete bioactive factors that exert diverse responses in vivo. In the present study, we explored mechanism how MSCs may lead to higher functional recovery in the animal stroke model.

The present study examined the effects of human umbilical cord blood-derived mesenchymal stem cells (HUCB-derived MSCs) delivered through the basilar artery in a canine thromboembolic brain ischemia model. Cerebral ischemia was induced through occlusion of the middle cerebral artery by injecting thrombus emboli into 10 beagles. In the HUCBC group (n = 5), 1 x 10(6) HUCB-derived MSCs were transplanted through the basilar artery 1 day after ischemic induction using an endovascular interventional approach. In the control group (n = 5), phosphate-buffered saline (PBS) was injected in the same manner in as the HUCBC group. Upon neurobehavioral examination, earlier recovery was observed in the HUCBC group. The HUCBC group showed a decrease in the infarction volume at 1 week after cerebral ischemic induction, whereas the control group showed an increase in the infarction volume at 1 week, by magnetic resonance image analysis. Transplanted cells had differentiated into neurons and astrocytes and were observed in and around endothelial cells that were positive for von Willebrand factor (vWF). HUCB-derived MSCs expressed neuroprotective factors, such as brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF), at 4 weeks after the transplantation. The transplanted cells demonstrated their efficacy by reducing the infarction lesion volume and through earlier recovery from the neurological deficit. These results suggest that intraarterial transplantation of HUCB-derived MSCs could be useful in clinical treatment of cerebral ischemia.

This study investigated the effect of 40% oxygen administration on n-back task performance, blood oxygen saturation and heart rate. Five male (25.8 +/- 1.3 years) and five female (23.0 +/- 1.0 years) college students were selected as the subjects for this study. The experiment consisted of two runs: one was an n-back task with normal air (21% oxygen) administered and the other was with hyperoxic air (40% oxygen) administered. The experimental sequence in each run consisted of Rest1 (1 min), 0-back task (1 min), 2-back task (2 min) and Rest2 (4 min). Blood oxygen saturation and heart rate were measured throughout the four phases. The results of the n-back behavioural analysis reveal that accuracy rates were enhanced with 40% oxygen administration compared to 21% oxygen. When 40% oxygen was supplied, blood oxygen saturation was increased and heart rate was decreased compared to that with 21% oxygen administration. It is suggested that 40% oxygen can stimulate brain activation by increasing actual blood oxygen concentration in the process of cognitive performance, and hyperoxia makes heart rate decrease. This result supports the hypothesis that 40% oxygen administration would lead to increases in n-back task performance.

In this paper, the accuracy and efficiency of various probabilistic methods are assessed for the vibration analysis of a mistuned bladed disk system with small, random bladeto-blade differences. A quantity of primary engineering interest is examined, namely the maximum resonant response amplitude of any blade in the assembly over a given frequency range. For the purpose of comparing the probabilistic methods, the response amplitude of a specific blade at a given resonant frequency is also considered. Initially, the following methods are applied to analyze the effects of small blade stiffness uncertainties for a lumpedparameter model of a 29-blade rotor: (1) a first-order reliability method (FORM), (2) a second-order reliability method (SORM), (3) an advanced mean value (AMV+) method, (4) a response surface method (RSM) using a moving least squares approach, and (5) a radius-based importance sampling method. In general, these methods do well in predicting the response statistics of a given blade at a given frequency, at least in limited ranges of uncertainties. However, all of these reliability-based methods fail to capture the statistics of the maximum resonant response across the blade assembly, regardless of the range of uncertainties. To circumvent this shortcoming, an accelerated Monte Carlo simulation (MCS) approach is also considered, which involves a combination of a small-sample MCS and a Weibull probability distribution fit. This method is found to predict the statistics of the largest resonant blade response over the blade assembly with great accuracy and efficiency. It is thus better suited to the analysis of bladed disk response statistics than the class of reliability-based probabilistic methods.

This study identifies differences in the electroencephalogram (EEG) responses caused by individual sensitivity to simulator sickness. Simulator sickness was investigated by studying the changes in simulator sickness in two different subject groups (sick group and nonsick group). Subjective evaluations using the simulator sickness questionnaire and the EEG response data were gathered every 5 min while the subjects were driving at 60 km/h for 60 min in the driving graphic simulator. The response to every item of the subjective evaluation increased linearly with time; the response level in the sick group was higher than in the nonsick group. The EEG analysis showed that the sick and nonsick groups were statistically significantly different with respect to the parameter theta/total at frontal lobe and parietal lobe.

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