Biomedical Engineering: Applications, Basis and Communications

This paper firstly reports the visual response to the inner light (a form of qi) and the outside stimulus during Zen meditation. It has been reported literally that inner light perception is the common experience for prayers or Zen-meditation practitioners. In this paper, we propose a method to quantify the EEG (electroencephalograph) and F-VEP (flash visual evoked potential) that characterize this experience.

Based on wavelet analysis, we derived a set of parameters that effectively signify the alpha-suppressed EEG pattern. Furthermore, this paper presents our new results of analyzing the F-VEP data, mainly the peak amplitude. The observation of little variation in amplitude during Zen meditation reflects a more stable visual perceptive system during Zen meditation that is contrary to the visual response of the control subjects under eye-closed relaxation.

The present study provides in vivo trials of silicone rubber chambers filled with different concentrations of bilobalide (0, 50, 100, 200, 400 μM) and Schwann cells (1.5 × 10⁵ cell/ml) in a 1:1 volumetric addition to bridge a 15 mm sciatic nerve defect in rats. At the conclusion of 8 weeks, histological technique was used to evaluate the functional recovery of the nerve. In the groups receiving the Schwann cells and bilobalide at 50, 100, 200 and 400 μM, 44% (4 of 9, one died during experiment), 50% (5 of 10), 30% (3 of 10), and 60% (6 of 10) of the animals exhibiting a regenerated nerve cable across the 15-mm gap, respectively. In comparison, 50% (5 of 10) of the animals in the group with Schwann cells only showed such regenerated nerve cables. Although the adding of bilobalide did not promote the nerve growth-promoting capability of Schwann cells in the nerve guides, the techniques we used in this study provided a new approach combining Chinese medicine and tissue engineering to nerve regeneration.

Polyurethane (PU) heart valves provide central flow at peak systole and the associated hemodynamic characteristics are superior to that of mechanical valves with almost no anticoagulation therapy for patients. Durability performances, on the other hand, are also superior to those of biological valves. This paper analyzes blood flow characteristics of the PU heart valves at fully open position with computational fluid dynamics. These data provide information for the improvement of leaflets and leaflet support geometry to minimize the scale of recirculation zone of the flow field. To simulate the hemodynamic characteristics of the blood flow, CFX-4.3 software with the finite volume method is utilized to analyze the three-dimensional Reynolds-averaged Navier-Stokes equations. By modifying the geometry of leaflets along with the supports, the scale of vortex flow and blood velocity are reduced obviously. Maximum flow velocity reduces 33% compared to that of original model at peak systole.

The peak stress, the weight beared area and the stress distributions of the articular contact at the human hip joint are the most important factors, which determine the location of the degenerative foci that later result in degenerative damage and in the development of osteoarthritis. In this paper, firstly a generalization analytical modelling for evaluating the peak stress, the weight beared area and the stress distributions of the articular contact at the human hip joint is developed; secondly, as an example, the numerical results for evaluating the peak stress, the weight beared area and the stress distributions of the articular contact at the human hip joint are presented. The results show that the numerical values from the present modelling are good agreement with the literatures.

In the past ten years, extracorporeal shock waves have been successfully used in orthopedics. The idea of shock wave therapy is the stimulation of a healing process. Electrohydraulic shock wave therapy provides higher energy density flux than electromagnetic and piezoelectric types. But electrohydraulic shock wave generators are less stable than the other two types because of electrode erosion. In this study, a shock wave generator with a controllable spark gap system has been designed in order to give steady output pressures by automatic adjustment of the electrode gap. An ellipsoidal shock wave reflector is equipped with two AC servo motors with drivers. The motor driver actuates the associated motor which is connected to an electrode base by a belt. On a designed image feedback system, a CCD camera is used as the image detection tool to measure the electrode gap. Experimental results show the coincidence of the second focus of the shock wave reflector with the gas-dynamic focus. Moreover, measurements of focused pressure and energy intensity with PCB and PVDF pressure sensors and tests of stone fragmentation efficiency have been carried out to evaluate the performance of the newly designed shock wave generator with a gap-adjusted system and an image feedback system. It is found that the designed electrohydraulic shock wave generator is stable and efficient in pressure output with a low cost of electrodes.

Following the previous study to intercalate a 5-fluorouracil (5-FU) into the interlayer spacing of montmorillonite (MMT) for colorectal cancer treatment, we selected a safe and non-pathological microorganism, Saccharomyces cerevisiae, as indicator microorganism to proceed risk assessment on MMT for feasibility study. Dose-response analysis from the perspective in toxicology was conducted to reveal the toxicity rankings of MMT, L-ascorbic acid (LAA) and montmorillonite-L-ascorbic acid (MMT-LAA) composites. This study also tended to intercalate LAA into MMT, observing chemical-structure stabilities of LAA-MMT composites. According to infrared spectroscopic analysis via FTIR, the lattice-vibration peaks of the distorted tetrahedron of SiO₄ for MMT were ranged in 400-1200 cm⁻¹. X-ray diffraction analysis also addressed the layer spacing changes in the MMT lattice with pH changes. The variation in the [001] d-spacing changed from 12.4 to 19.4 Å with the increased pH, allowing higher intercalation of viable compounds (e.g., LAA) for controlled-release applications. Compared to MMT, LAA, the lowest toxicity (e.g., EC₅₀=3.77°10⁵ppm) of the hybrid MMT-LAA also strongly suggested that MMT-LAA composite is safe to be used for further applications. In contrast, the lowest EC₀ (0.564 ppm) suggested the most sensitive characteristics for MMT-LAA composite to induce the toxic response from no-effect condition. MMT is thus feasible for intercalation of LAA in controlled release to pH changes; particularly, MMT-LAA is considered non-toxic for further applications.

Calcium ion concentration is proposed to be involved in the regulation of the proliferative capacity of keratinocytes, based on its significant actions in the skin. These actions are mediated by Ca²⁺ influx and inhibition of cell proliferation. To define Ca²⁺ action in the keratinocyte we investigated its effects on the proliferation and differentiation using the primary keratinocytes model. Primary keratinocytes were incubated in DMEM (containing 1.2mM calcium ion concentration) or DK11 medium (containing 0.4 mM calcium ion concentration) or K medium (containing 0.03mM calcium ion concentration). Cell viability was assessed with the MTT assay. Crystal violet assay was evaluated the proliferation rate and colony formation size of keratinocyte. Real-time PCR used to determine the terminal differentiated keratinocyte which expressed Caspase-14. Proliferation assays and real°Vtime PCR were correlated with either proliferation or differentiation in cultured human skin epidermal keratinocytes.

High Ca²⁺ concentration was inhibited the cell viability and proliferation rate of keratinocyte. Ca²⁺ also increased caspases-14 expression, and inhibited cell viability, and cell colony forming efficiency. These results are consistent with Ca²⁺ induction of the keratinocyte differentiation. Thus, the overall Ca²⁺ actions connote protective functions for the epidermis that appear to include the triggering or acceleration of the differentiation.

We have developed a chitosan-based melanocyte patch to improve the drawbacks encountered in autologous melanocyte transplantation for vitiligo treatment by use of melanocyte suspension. Melanocytes spontaneously grow into three dimensional spheroids on chitosan-coated surface and melanocyte spheroids show a better survival in growth factor and serum-deprived condition. Hence, preculturing melanocytes into spheroids on chitosan surface can provide melanocytes a survival advantage in stringent conditions. Up to date, the mechanism of the melanocyte spheroid formation is not clear. It has been shown that certain factors in serum are crucial for multicellular spheroid formation in cancer cell lines. In this work, we investigate the effect of serum concentration on the melanocyte spheroid formation. The trend for melanocyte spheroid formation is gradually decreased when serum concentration is serially increased from 0% to 20%. Our result shows that melanocyte spheroid formation is not inhibited in the absence of serum and serum deprivation accelerates melanocyte spheroid formation. However, melanocyte growth is greatly reduced when serum is completely removed. Our results suggest that melanocyte spheroid formation on chitosan is not dependent on serum factors. However, the presence of serum contributes to the cell growth on chitosan-coated surface. This result is important in the future development of serum free culture system for spheroidal melanocyte patch.