Browsing by Subject "digital image analysis"

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    A Comparative Analysis of Local and Global Peripheral Nerve Mechanical Properties During Cyclical Tensile Testing
    (2022-05) Doering, Onna Marie; Yoshida, Ken; Wallace, Joseph; Goodwill, Adam
    Understanding the mechanical properties of peripheral nerves is essential for chronically implanted device design. The work in this thesis aimed to understand the relationship between local deformation responses to global strain changes in peripheral nerves. A custom-built mechanical testing rig and sample holder enabled an improved cyclical uniaxial tensile testing environment on rabbit sciatic nerves (N=5). A speckle was placed on the surface of the nerve and recorded with a microscope camera to track local deformations. The development of a semi-automated digital image processing algorithm systematically measured local speckle dimension and nerve diameter changes. Combined with the measured force response, local and global strain values constructed a stress-strain relationship and corresponding elastic modulus. Preliminary exploration of models such as Fung and 2-Term Mooney-Rivlin confirmed the hyperelastic nature of the nerve. The results of strain analysis show that, on average, local strain levels were approximately five times smaller than globally measured strains; however, the relationship was dependent on global strain magnitude. Elastic modulus values corresponding to ~9% global strains were 2.070 ± 1.020 MPa globally and 10.15 ± 4 MPa locally. Elastic modulus values corresponding to ~6% global strains were 0.173 ± 0.091 MPa globally and 1.030 ± 0.532 MPa locally.
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    Using quantitative intravital multiphoton microscopy to dissect hepatic transport in rats
    (Elsevier, 2017) Dunn, Kenneth W.; Ryan, Jennifer C.; Department of Medicine, IU School of Medicine
    Hepatic solute transport is a complex process whose disruption is associated with liver disease and drug-induced liver injury. Intravital multiphoton fluorescence excitation microscopy provides the spatial and temporal resolution necessary to characterize hepatic transport at the level of individual hepatocytes in vivo and thus to identify the mechanisms and cellular consequences of cholestasis. Here we present an overview of the use of fluorescence microscopy for studies of hepatic transport in living animals, and describe how we have combined methods of intravital microscopy and digital image analysis to dissect the effects of drugs and pathological conditions on the function of hepatic transporters in vivo.