Microvascular research
-
Microvascular research · Sep 2011
Comparative StudyComparison between laser speckle contrast imaging and laser Doppler imaging to assess skin blood flow in humans.
We tested the linearity between skin blood flux recorded with laser speckle contrast imaging (LSCI) and laser Doppler imaging (LDI), comparing different ways of expressing data. A secondary objective was to test within-subject variability of baseline flux with the two techniques. ⋯ This study suggests that skin blood flux measured with LSCI is linearly related to the LDI signal over a wide range of perfusion. Subtracting BZ does not affect this linearity but introduces variability in baseline flux, thus decreasing the correlation when data are expressed as a function of baseline. Finally, systematic bias makes it impossible to assimilate arbitrary perfusion units provided by the two systems.
-
Microvascular research · Jul 2011
Automated computation of functional vascular density using laser speckle imaging in a rodent window chamber model.
We report a methodology for computing functional vascular density within a rodent dorsal window chamber model based on long-exposure laser speckle imaging (LSI). This technique relies on the presence of flow to create detailed vasculature maps. ⋯ Additionally, a freeware algorithm for computing functional vascular density (FVD) from images acquired using long-exposure LSI is also described to facilitate ease in adopting this method. We demonstrate that together these tools can be used to compute FVD nearly twelve times faster than manual computation, yet with comparable accuracy.
-
Microvascular research · May 2011
ROCK induced inflammation of the microcirculation during endotoxemia mediated by nitric oxide synthase.
Sepsis may be modeled using lipopolysaccharide (LPS), which alters levels of nitric oxide (NO), synthesized via endothelial and inducible nitric oxide synthase (eNOS and iNOS). This study aimed to determine whether the Rho kinase (ROCK) inhibitor fasudil protected against LPS-induced (endotoxemia) macromolecular leak and leukocyte adhesion via NOS pathways. Male Wistar rats (283±8g, n=36) were anaesthetized with thiopental and the mesentery prepared for fluorescent intravital microscopy (IVM). ⋯ Immunohistochemistry demonstrated that fasudil increased endothelial cell expression of eNOS during sepsis, and decreased LPS-induced up-regulation of iNOS. Inhibition of ROCK in rats increases eNOS and decreases iNOS during endotoxemia, concomitantly reducing microvascular inflammation. Thus, targeting the ROCK pathway during sepsis could have therapeutic potential for reducing inflammation via a NO dependent mechanism.
-
Microvascular research · Mar 2011
Circulating endothelial and endothelial progenitor cells in patients with severe sepsis.
Elevated circulating endothelial cell (CEC) and circulating endothelial progenitor cell (CEPC) counts may indicate vascular damage and disease status, but data on these cell populations in patients with severe sepsis are limited. This study compared CEC and CEPC counts in patients with and without severe sepsis following intensive care unit (ICU) admission. Venous blood samples were collected within 24 h, 48-72 h, and 120-144 h. ⋯ CEPC counts in both cohorts ranged from 0 to >21 colonies/4 ml blood (mean=1.13±2.25; median=0) without significant differences at any time point. This study demonstrates the ability to quantify CECs and CEPCs using consensus methodology. Understanding the relationship between CEC/CEPC counts and outcomes may provide insight into the mechanisms of endothelial cell changes in severe sepsis.
-
Microvascular research · Dec 2010
Randomized Controlled Trial Comparative StudyTissue viability imaging for assessment of pharmacologically induced vasodilation and vasoconstriction in human skin.
Tissue viability imaging (TIVI) is a novel polarization spectroscopy method for assessing dermal vascular viability. The purpose of the present study was to compare TIVI with laser Doppler flowmetry (LDF) for assessment of pharmacologically induced vasodilation and vasoconstriction in human skin. Eight individual skin sites on the backs of seven healthy volunteers were randomized to receive an intradermal injection of prostaglandin E2 (PGE2, 10(-6) to 10(-9)M), norepinephrine (NE, 10(-5) to 10(-7)M), or vehicle. ⋯ There was a modest though significant correlation between relative changes in vascular responses measured by the two methods (p<0.0001, r(2)=0.521). A Bland-Altman difference plot demonstrated significant underestimation of relative increase versus baseline measured by TIVI (r(2)=0.99, p<0.0001). We conclude that TIVI polarization spectroscopy is a sensitive method for measurement of NE-induced vascular responses but that it is less sensitive than LDF for measurement of the PGE2-induced reactions.