Microbubble-mediated pore formation in sonoporation includes a combination of complex processes such as collision or coalescence of translating or collapsing microbubbles with vascular cells. Although understanding th...Microbubble-mediated pore formation in sonoporation includes a combination of complex processes such as collision or coalescence of translating or collapsing microbubbles with vascular cells. Although understanding the pore formation mechanisms may improve drug delivery efficiency, their details are still poorly understood. In the present study, we describe an experimental model that produces single air bubbles with controllable size. A carbon microfiber in liquids is illuminated by an infrared laser to produce individual bubbles having size comparable to that of the microfiber. The microbubbles can be physically isolated from the fiber for placing at arbitrary positions in the liquids. The lifetime of the bubbles is several tens of minutes depending on the intensity of the laser used. The preparation of the controllable air bubbles may be useful in future investigations of ultrasound-mediated microbubble–cell interactions.展开更多
The geometric and biomechanical properties of the larynx strongly influence voice quality and efficiency. A physical understanding of phonation natures in pathological conditions is important for predictions of how vo...The geometric and biomechanical properties of the larynx strongly influence voice quality and efficiency. A physical understanding of phonation natures in pathological conditions is important for predictions of how voice disorders can be treated using therapy and rehabilitation. Here, we present a continuum-based numerical model of phonation that considers complex fluid-structure interactions occurring in the airway. This model considers a three-dimensional geometry of vocal folds, muscle contractions, and viscoelastic properties to provide a realistic framework of phonation. The vocal fold motion is coupled to an unsteady compressible respiratory flow, allowing numerical simulations of normal and diseased phonations to derive clear relationships between actual laryngeal structures and model parameters such as muscle activity. As a pilot analysis of diseased phonation, we model vocal nodules, the mass lesions that can appear bilaterally on both sides of the vocal folds. Comparison of simulations with and without the nodules demonstrates how the lesions affect vocal fold motion, consequently restricting voice quality. Furthermore, we found that the minimum lung pressure required for voice production increases as nodules move closer to the center of the vocal fold. Thus, simulations using the developed model may provide essential insight into complex phonation phenomena and further elucidate the etiologic mechanisms of voice disorders.展开更多
We present a new technique for estimating cell surface geometry. A dish supporting adherent cells is observed using oblique transillumination and rotated in the horizontal plane using a stepping motor. The stage rotat...We present a new technique for estimating cell surface geometry. A dish supporting adherent cells is observed using oblique transillumination and rotated in the horizontal plane using a stepping motor. The stage rotation-dependent movements of the start and end points of a shadow formed behind the illuminated cells uniquely determine the relative height differences between points along the cell surface. Thus, using custom-made apparatuses and living endothelial cells, we demonstrate that the combination of a rotating stage and oblique lighting allows for the evaluation of three-dimensional surface geometry of adherent cells. As compared to confocal microscopy and atomic force microscopy, which are commonly used for measuring cell surface geometry, this approach can be performed rapidly and is especially suitable for the observation of unstained cells over a large surface covering multiple cells at a time.展开更多
文摘Microbubble-mediated pore formation in sonoporation includes a combination of complex processes such as collision or coalescence of translating or collapsing microbubbles with vascular cells. Although understanding the pore formation mechanisms may improve drug delivery efficiency, their details are still poorly understood. In the present study, we describe an experimental model that produces single air bubbles with controllable size. A carbon microfiber in liquids is illuminated by an infrared laser to produce individual bubbles having size comparable to that of the microfiber. The microbubbles can be physically isolated from the fiber for placing at arbitrary positions in the liquids. The lifetime of the bubbles is several tens of minutes depending on the intensity of the laser used. The preparation of the controllable air bubbles may be useful in future investigations of ultrasound-mediated microbubble–cell interactions.
文摘The geometric and biomechanical properties of the larynx strongly influence voice quality and efficiency. A physical understanding of phonation natures in pathological conditions is important for predictions of how voice disorders can be treated using therapy and rehabilitation. Here, we present a continuum-based numerical model of phonation that considers complex fluid-structure interactions occurring in the airway. This model considers a three-dimensional geometry of vocal folds, muscle contractions, and viscoelastic properties to provide a realistic framework of phonation. The vocal fold motion is coupled to an unsteady compressible respiratory flow, allowing numerical simulations of normal and diseased phonations to derive clear relationships between actual laryngeal structures and model parameters such as muscle activity. As a pilot analysis of diseased phonation, we model vocal nodules, the mass lesions that can appear bilaterally on both sides of the vocal folds. Comparison of simulations with and without the nodules demonstrates how the lesions affect vocal fold motion, consequently restricting voice quality. Furthermore, we found that the minimum lung pressure required for voice production increases as nodules move closer to the center of the vocal fold. Thus, simulations using the developed model may provide essential insight into complex phonation phenomena and further elucidate the etiologic mechanisms of voice disorders.
文摘We present a new technique for estimating cell surface geometry. A dish supporting adherent cells is observed using oblique transillumination and rotated in the horizontal plane using a stepping motor. The stage rotation-dependent movements of the start and end points of a shadow formed behind the illuminated cells uniquely determine the relative height differences between points along the cell surface. Thus, using custom-made apparatuses and living endothelial cells, we demonstrate that the combination of a rotating stage and oblique lighting allows for the evaluation of three-dimensional surface geometry of adherent cells. As compared to confocal microscopy and atomic force microscopy, which are commonly used for measuring cell surface geometry, this approach can be performed rapidly and is especially suitable for the observation of unstained cells over a large surface covering multiple cells at a time.
