News / Meetings



NWG Göttingen 2019
13th meeting of the German Neuroscience Society

Mar 20-23, 2019, Göttingen, Germany
Booth No. 8


SFN - Neuroscience 2019
50th annual meeting of the Society for Neuroscience

Oct 19-23, 2019, Chicago, IL, USA
Booth No. 1468


BPS San Diego 2020
64th annual meeting of the Biophysical Society

Feb 15-19, 2020 San Diego, CA, USA
Booth No. 710

Microparticle Velocity Measurements

Micro-Particle Tracking Velocimetry (MPTV)

Leukocyte adhesion is determined by the balance between molecular adhesive forces and convective dispersive forces. A key parameter influencing leukocyte adhesion is the shear stress acting on the leukocyte. This measure is indispensable for determining the molecular bond forces and estimating cell deformation.

This shear stress was experimentally determined using microparticle tracking velocimetry (Micro-PTV). More than 24000 images were taken at 20-25 fps and analysed.

a. The measured MPTV velocity field is displayed as arrows and superimposed on a representative intravital fluorescence image of adhered eGFP-expressing leukocyte for A-C). Arrows represent individual velocity measurements with length and direction proportional to the measured velocity vector. Vessel walls are marked by highlighted horizontal lines. The white boxes (lower left corners) mark the area where data was used to calculate the wall shear rates. b. Velocity measurements near leukocytes and within 4µm of the leukocyte or vessel wall (white arrows). Leukocyte and vessel borders shown as solid and dotted lines, respectively. Solid scale bar is 5µm, arrow scale bar is 1000µm/s (A and B) or 2000µm/s (C).

The images were taken using a CCD camera which triggered the Xenon flash lamp DPS-2. The flash lamp is a dual-strobe lamp with a user-defined delay of 0.1-99 ms between the first and the second pulse. The flash duration was 20µs.


From: Pickard JE, Ley K (2009), Micro-PTV Measurement of the Fluid Shear Stress Acting On Adherent Leukocytes In Vivo, Biophys. J., Vol. 96, 4249-4259

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