Spatially resolved measurements of hyperpolarized gas properties in the lung in vivo. Part I: Diffusion coefficient

Filopodia are dynamic, actin-rich structures that transiently form on a variety of cell types. To understand the underlying control mechanisms requires precise monitoring of localization and concentration of individual regulatory and structural proteins as filopodia elongate and subsequently retract. Although several methods exist that analyze changes in filopodial shape, a software solution to reliably correlate growth dynamics with spatially resolved protein concentration along the filopodium independent of bending, lateral shift, or tilting is missing. Here we introduce a novel approach based on the convex-hull algorithm for parallel analysis of growth dynamics and relative spatiotemporal protein concentration along flexible filopodial protrusions. Detailed in silico tests using various geometries confirm that our technique accurately tracks growth dynamics and relative protein concentration along the filopodial length for a broad range of signal distributions. To validate our technique in living cells, we measure filopodial dynamics and quantify spatiotemporal localization of filopodia-associated proteins during the filopodial extension–retraction cycle in a variety of cell types in vitro and in vivo. Together these results show that the technique is suitable for simultaneous analysis of growth dynamics and spatiotemporal protein enrichment along filopodia. To allow readily application by other laboratories, we share source code and instructions for software handling.

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In Vivo Experimental and Analytical Studies for Bevacizumab Diffusion Coefficient Measurement in the Rabbit Vitreous Humor

Journal of Heat Transfer ◽

10.1115/1.4049033 ◽

2020 ◽

Author(s):

Shuqi Zhang ◽

Anita Penkova ◽

Mark Humayun ◽

Juan Carlos Martinez-Camarillo ◽

Abegail C. Tadle ◽

...

Keyword(s):

Diffusion Coefficient ◽

Effective Diffusion ◽

Drug Distribution ◽

Vitreous Humor ◽

Contour Method ◽

Experimental Result ◽

Coefficient Measurement ◽

A New Technique ◽

Best Fit

Abstract In order to measure the effective diffusion coefficient of Bevacizumab (Avastin, Genentech) in the vitreous humor, a new technique is developed based on the 'contour method' and in vivo OCT measurements. After injection of Bevacizumab-fluorescein conjugated compound solution into the rabbit eye, the contours of drug concentration distribution at the subsurface of injection were tracked over time. The 2D contours were extrapolated to 3D contours using reasonable assumptions and a numerically integrated analytical model was developed for the theoretical contours for the irregularly shaped drug distribution in the experimental result. By floating the diffusion coefficient, different theoretical contours were constructed and the least-squares best fit to the experimental contours was performed at each time point to get the best fit solution. The approach generated consistent diffusion coefficient values based on the experiments on four rabbit eyes over a period of 3 hours each, which gave , D=1.2±0.6×(?10?^(-6) ?cm?^2)/s and the corresponding theoretical contours matched well with the experimental contours. The quantitative measurement of concentration using OCT and fluorescein labeling gives a new approach for the "non-contact" in vivo drug distribution measurement within vitreous and other ocular tissues.

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Spatiotemporal co-dependency between macrophages and exhausted CD8+ T cells in cancer

10.1101/2021.09.27.461866 ◽

2021 ◽

Author(s):

Kelly Kersten ◽

Kenneth H Hu ◽

Alexis J Combes ◽

Bushra Samad ◽

Tory Harwin ◽

...

Keyword(s):

T Cells ◽

Cd8 T Cells ◽

Light Sheet ◽

Light Sheet Microscopy ◽

Spatially Resolved ◽

Hypoxic Conditions ◽

Synaptic Interactions ◽

Positive Feedback Circuit ◽

Major Impediment

T cell exhaustion is a major impediment to anti-tumor immunity. However, it remains elusive how other immune cells in the tumor microenvironment (TME) contribute to this dysfunctional state. Here we show that the biology of tumor-associated macrophages (TAM) and exhausted T cells (Tex) in the TME is extensively linked. We demonstrate that in vivo depletion of TAM reduces exhaustion programs in tumor-infiltrating CD8+ T cells and reinvigorates their effector potential. Reciprocally, transcriptional and epigenetic profiling reveals that Tex express factors that actively recruit monocytes to the TME and shape their differentiation. Using lattice light sheet microscopy, we show that TAM and CD8+ T cells engage in unique long-lasting antigen-specific synaptic interactions that fail to activate T cells, but prime them for exhaustion, which is then accelerated in hypoxic conditions. Spatially resolved sequencing supports a spatiotemporal self-enforcing positive feedback circuit that is aligned to protect rather than destroy a tumor.

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Investigation of techniques to quantify in vivo lesion volume based on comparison of water apparent diffusion coefficient (adc) maps with histology in focal cerebral ischemia of rats

Magnetic Resonance Imaging ◽

10.1016/j.mri.2004.01.043 ◽

2004 ◽

Vol 22 (5) ◽

pp. 653-659 ◽

Cited By ~ 12

Author(s):

Mark Kazemi ◽

Matthew D. Silva ◽

Fuhai Li ◽

Marc Fisher ◽

Christopher H. Sotak

Keyword(s):

Diffusion Coefficient ◽

Cerebral Ischemia ◽

Apparent Diffusion Coefficient ◽

Focal Cerebral Ischemia ◽

Lesion Volume ◽

Apparent Diffusion

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In vivo near infra-red spectroscopy instrumentation combining spatially-resolved and intensity modulation techniques

IEEE EMBS Asian-Pacific Conference on Biomedical Engineering, 2003. ◽

10.1109/apbme.2003.1302705 ◽

2004 ◽

Author(s):

P. Rolfe

Keyword(s):

Intensity Modulation ◽

Spatially Resolved ◽

Spectroscopy Instrumentation ◽

Modulation Techniques ◽

Infra Red

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Composition dependent transport diffusion in non-ideal mixtures from spatially resolved nuclear magnetic resonance spectroscopy

Physical Chemistry Chemical Physics ◽

10.1039/c8cp05539d ◽

2018 ◽

Vol 20 (44) ◽

pp. 28185-28192 ◽

Cited By ~ 2

Author(s):

Christian F. Pantoja ◽

Y. Mauricio Muñoz-Muñoz ◽

Lorraine Guastar ◽

Jadran Vrabec ◽

Julien Wist

Keyword(s):

Nuclear Magnetic Resonance ◽

Diffusion Coefficient ◽

Nmr Spectroscopy ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Resonance Spectroscopy ◽

Spatially Resolved ◽

Transport Diffusion ◽

Dependent Transport ◽

Nuclear Magnetic

Nuclear magnetic resonance (NMR) spectroscopy can also be used for the measurement of the Fick diffusion coefficient.

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Temperature dependence of oxygen diffusion and consumption in mammalian striated muscle

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.264.6.h1825 ◽

1993 ◽

Vol 264 (6) ◽

pp. H1825-H1830 ◽

Cited By ~ 21

Author(s):

T. B. Bentley ◽

H. Meng ◽

R. N. Pittman

Keyword(s):

Diffusion Coefficient ◽

Steady State ◽

Oxygen Diffusion ◽

Striated Muscle ◽

Effect Of Temperature ◽

Retractor Muscle ◽

Oxygen Solubility ◽

Order Of Magnitude

This study investigated the effect of temperature on the oxygen diffusion coefficient (DO2) of hamster retractor muscle from 11 to 37 degrees C. DO2 was measured using a non-steady-state technique, whereas muscle O2 consumption (VO2) was estimated after steady state was reached. DO2 was 0.84 +/- 0.04 x 10(-5) cm2/s at 11 degrees C and rose exponentially to 2.41 +/- 0.19 x 10(-5) cm2/s at 37 degrees C, producing a temperature coefficient for DO2 of 4.60%/degrees C for this temperature range. To measure DO2 directly at 37 degrees C, it was necessary to inhibit tissue VO2 with Amytal. The DO2 measurements made at 37 degrees C were significantly higher than previously reported values, which had been based on extrapolations from lower temperatures (6). Further analysis suggests a possible transition in the diffusion pathway between 23 and 30 degrees C, resulting in a DO2 higher than that previously expected. This larger DO2, together with a recently published value of oxygen solubility (alpha) (21), results in an in vitro Krogh's diffusion coefficient (KO2) that is 2.4 times larger than that previously reported (24) and therefore significantly reduces an order of magnitude discrepancy between in vitro and estimated in vivo KO2 values (24). Muscle VO2 was 0.35 ml O2.min-1.100 g-1 at 11 degrees C and increased with temperature, resulting in an activation energy of the rate-limiting reaction from the Arrhenius equation of -10.5 kcal/mol between 11 and 30 degrees C.

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