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John Turek

Publications and source records attributed to John Turek.

2 recordsLinked to original sources

Chemosensitivity testing of revived fresh-frozen biopsies using digital speckle holography

Enrolling patients in clinical trials to obtain fresh tumor biopsies to profile anticancer agents can be slow and expensive. However, if flash-frozen biopsies can be thawed to produce viable living tissue with relevant biodynamic profiles, then a large reservoir of tissue-banked samples could become available for phenotypic library building. Here, we report biodynamic profiles acquired from revived flash-frozen canine B-cell lymphoma biopsies using digital speckle holography. We compared the thawed-tissue drug-response spectrograms to spectrograms from fresh tissues in a study of canine B-cell lymphoma. By compensating for tissue trauma in the thawed sample, patient clustering of both the fresh and thawed samples were found to be in general agreement with clinical outcomes. This study indicates that properly frozen tumor specimens are a viable proxy for fresh specimens in the context of chemosensitivity testing, and that thawed samples from tissue banks contain sufficient viable cells to evaluate phenotypic drug response.

physics.bio-ph

Doppler Fluctuation Spectroscopy of Intracellular Dynamics in Living Tissue

Intracellular dynamics in living tissue are dominated by active transport driven by bioenergetic processes far from thermal equilibrium. Intracellular constituents typically execute persistent walks. In the limit of long mean-free paths, the persistent walks are ballistic, exhibiting a "Doppler edge" in light scattering fluctuation spectra. At shorter transport lengths, the fluctuations are described by lifetime-broadened Doppler spectra. Dynamic light scattering from transport in the ballistic, diffusive or the cross-over regime is derived analytically, including the derivation of autocorrelation functions through a driven damped harmonic oscillator analog for light scattering from persistent walks. The theory is validated through Monte Carlo simulations. Experimental evidence for the Doppler edge in 3D living tissue is obtained using biodynamic imaging based on low-coherence interferometry and digital holography.

q-bio.QM