A three-dimensional particle tracking velocimeter for measuring an instantaneous distribution of all the three velocity components in a liquid flow is developed using an automated digital image processing technique. The measurement system consists of three TV cameras, a digital image processor, a laser disk recorder and a 16-bit microcomputer. Motions of neutrally buoyant tracer particles introduced into the flow field are observed by the cameras, and the three-dimensional displacement of each particle is calculated from consecutive TV frames recorded on the laser disk. Instantaneous velocity profiles in an unsteady laminar Couette flow between two concentric cylinders are measured. The results are in good agreement with predictions within the measurement uncertainties evaluated systematically. Furthermore, the measurement of a decaying turbulence in a stirred water tank demonstrates that the present technique is applicable to turbulent flows.
Adipose-derived stem cells (ADSCs) are attracting increased attention as a novel source in regenerative medicine. Transplantation of ADSCs promotes functional recovery in animal models of peripheral nerve injury, but the mechanism of enhanced nerve regeneration remains to be elucidated. In addition, it is important to examine whether the supportive functions of ADSCs are dependent on donor age or anatomic site of origin. In this study, we examined the effects of factors produced by mouse ADSCs on Schwann cells (SCs) and dorsal root ganglion (DRG) neurons in vitro and compared these effects among ADSCs from donors of different age and from different anatomic regions. ADSC-derived soluble factors supported survival and proliferation of SCs and promoted neurite outgrowth in DRG neurons. These beneficial effects were far superior to that of factors from 3T3-L1 cells and comparable to those of SC- and astrocyte (AC)-derived factors. ADSCs from different sources similarly retained their neurotrophic activity. Real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay analyses demonstrated that ADSCs produced various growth factors, some of which were more abundant than in SCs and ACs. These results suggest that ADSCs promote peripheral nerve regeneration partly through paracrine secretion of trophic factors and regardless of donor age or anatomic site of origin.
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