Doppler flow imaging of cytoplasmic streaming using spectral domain phase microscopy.
ABSTRACT Spectral domain phase microscopy (SDPM) is a function extension of spectral domain optical coherence tomography. SDPM achieves exquisite levels of phase stability by employing common-path interferometry. We discuss the theory and limitations of Doppler flow imaging using SDPM, demonstrate monitoring the thermal contraction of a glass sample with nanometer per second velocity sensitivity, and apply this technique to measurement of cytoplasmic streaming in an Amoeba proteus pseudopod. We observe reversal of cytoplasmic flow induced by extracellular CaCl2, and report results that suggest parabolic flow of cytoplasm in the A. proteus pseudopod.
- SourceAvailable from: Sulma I Mohammed
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- "To overcome such site-to-site variability, laser Doppler imaging  or laser speckle imaging ,  have been used to visualize heterogeneous blood flow in a relatively large tissue area. Doppler optical coherence tomography ,  has also shown to visualize the functional information of blood flow in a relatively deeper region on a complementary structural image of optical coherence tomography. Instead of the blood flow measurements, multispectral imaging has been recently developed to quantitatively monitor blood volume and oxygen saturation with a large field of view of approximately 250 mm 2 with relatively low resolution . "
ABSTRACT: There is emerging evidence that microvascular alterations may occur early, even at early stages of carcinogenesis, as indispensable participants in tumor growth. However, the exact spatial extents of such alterations remain unclear, in part, because detailed microvascular alterations in relatively deep tissue over a relative large area are not easily visualized. Due to the heterogeneous nature of tissue microvasculature, microscopic evaluations with a small field of view often fail to provide a representative assessment. On the other hand, conventional whole-body small-animal optical imaging techniques suffer from unwanted diffuse light, which would otherwise deteriorate image contrast and resolution. To fill such a gap, we take advantage of the high anisotropic property of biological tissue by implementing back-directional gating into an imaging platform to suppress unwanted diffuse light. We further combine a spectral analysis of microvascular hemoglobin (Hb) absorption with back-directional gated imaging to improve image resolution, contrast, and penetration depth that are required for subcutaneous mouse xenograft models. In tissue phantom and pilot animal studies, we demonstrate that our diffuse-light-suppressed spectroscopic imaging platform can be a simple, yet effective, imaging setup to visualize subcutaneous microvascular Hb content over a relatively large area.IEEE Journal of Selected Topics in Quantum Electronics 09/2010; 16(4-16):815 - 823. DOI:10.1109/JSTQE.2009.2037160 · 3.47 Impact Factor
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- "The capabilities of MRV have already found application in a range of settings which aid the development and validation of numerical codes or theoretical models, for example the visualization of microfluidics flows (Akpa et al. 2007), the imaging of structure and convection in solidifying mushy layers (Aussillous et al. 2006), bifurcation phenomena in the flow through a sudden expansion in a circular pipe (Mullin et al. 2009) and velocity distributions within a three-dimensional vibro-fluidized bed (Huntley et al. 2007). With sufficient time-averaging, spatial resolutions of 10–100 μm can be achieved, allowing imaging of biological systems on scales just slightly larger than those of typical single cells (Choma et al. 2006). This has allowed measurements at tissue level in a variety of plant systems (Scheenen et al. 2001; Kockenberger et al. 2004; Windt et al. 2006); it is in the uniquely sized internodes of Chara that we can obtain measurements of flows internal to single cells. "
ABSTRACT: In the giant cylindrical cells found in Characean algae, multitudes of the molecular motor myosin transport the cytoplasm along opposing spiralling bands covering the inside of the cell wall, generating a helical shear flow in the large central vacuole. It has been suggested that such flows enhance mixing within the vacuole (van de Meent, Tuval & Goldstein, Phys. Rev. Lett., vol. 101, 2008, paper no. 178102) and thereby play a role in regulating metabolism. For this to occur the membrane that encloses the vacuole, namely the tonoplast, must transmit efficiently the hydrodynamic shear generated in the cytoplasm. Existing measurements of streaming flows are of insufficient spatial resolution and extent to provide tests of fluid mechanical theories of such flows and information on the shear transmission. Here, using magnetic resonance velocimetry (MRV), we present the first measurements of cytoplasmic streaming velocities in single living cells. The spatial variation of the longitudinal velocity field in cross-sections of internodal cells of Chara corallina is obtained with spatial resolution of 16 μm and is shown to be in quantitative agreement with a recent theoretical analysis (Goldstein, Tuval & van de Meent, Proc. Natl. Acad. Sci. USA, vol. 105, 2008, p. 3663) of rotational cytoplasmic streaming driven by bidirectional helical forcing in the cytoplasm, with direct shear transmission by the tonoplast. These results highlight the open problem of understanding tonoplast motion induced by streaming. Moreover, this study suggests the suitability of MRV in the characterization of streaming flows in a variety of eukaryotic systems and for microfluidic phenomena in general.Journal of Fluid Mechanics 01/2010; 642:5 - 14. DOI:10.1017/S0022112009992187 · 2.29 Impact Factor
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- "Another way is the extension of the application field. The capability of imaging with high spatial and time resolution of the scattering media structure and flows embedded into these media allows one to conduct detailed investigations of the structure and the functioning of the blood microcirculation system of humans or animals , imaging of embryonal development , as well as the study of cell motility dynamics  . "
ABSTRACT: The Doppler optical coherence tomography technique was applied to image the oscillatory dynamics of protoplasm in the strands of the plasmodium of slime mould Physarum polycephalum. Radial contractions of the gel-like walls of the strands and the velocity distributions in the sol-like endoplasm streaming along the plasmodial strands are imaged. The motility inhibitor effect of carbon dioxide on the cytoplasm shuttle flow and strand-wall contraction is shown. The optical attenuation coefficient of cytoplasm is estimated.Journal of Biophotonics 09/2009; 2(8-9):540-7. DOI:10.1002/jbio.200910057 · 3.86 Impact Factor