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Leukocyte adhesion to the endothelium is an important early step in the initiation and progression of sepsis. The endothelial glycocalyx layer (EGL) has been implicated in neutrophil adhesion and barrier dysfunction, but studies in this area are few. In this report, we examine the hypothesis that damage to the structure of the EGL caused by inflammation leads to increased leukocyte adhesion and endothelial barrier dysfunction. We used human umbilical vein endothelial cells enzymatically treated to remove the EGL components hyaluronic acid (HA) and heparan sulfate (HS) as a model for EGL damage. Using atomic force microscopy, we show reductions in EGL thickness after removal of either HA or HS individually, but the largest decrease, comparable with TNF-α treatment, was observed when both HA and HS were removed. Interestingly, removal of HS or HA individually did not affect neutrophil adhesion significantly, but removal of both constituents resulted in increased neutrophil adhesion. To test EGL contributions to endothelial barrier properties, we measured transendothelial electrical resistance (TEER) and diffusion of fluorescently labeled dextran (10 kDa molecular weight) across the monolayer. Removal of EGL components decreased TEER but had an insignificant effect on dextran diffusion rates. The reduction in TEER suggests that disruption of the EGL may predispose endothelial cells to increased rates of fluid leakage. These data support the view that damage to the EGL during inflammation has significant effects on the accessibility of adhesion molecules, likely facilitates leukocyte adhesion, and may also contribute to increased rates of fluid transport into tissues.

Disruption of endothelial cell-cell contact is a key event in many cardiovascular diseases and a characteristic of pathologically activated vascular endothelium. The CCM (cerebral cavernous malformation) family of proteins (KRIT1 (Krev-interaction trapped 1), PDCD10, and CCM2) are critical regulators of endothelial cell-cell contact and vascular homeostasis. Here we show novel regulation of vascular endothelial growth factor (VEGF) signaling in KRIT1-depleted endothelial cells. Loss of KRIT1 and PDCD10, but not CCM2, increases nuclear β-catenin signaling and up-regulates VEGF-A protein expression. In KRIT1-depleted cells, increased VEGF-A levels led to increased VEGF receptor 2 (VEGFR2) activation and subsequent alteration of cytoskeletal organization, migration, and barrier function and to in vivo endothelial permeability in KRIT1-deficient animals. VEGFR2 activation also increases β-catenin phosphorylation but is only partially responsible for KRIT1 depletion-dependent disruption of cell-cell contacts. Thus, VEGF signaling contributes to modifying endothelial function in KRIT1-deficient cells and microvessel permeability in Krit1(+/-) mice; however, VEGF signaling is likely not the only contributor to disrupted endothelial cell-cell contacts in the absence of KRIT1.

In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar ∗∗ → Ar 2+ + 2e. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation dynamics. We estimated the ionization time difference between the two electrons from NSDI of argon and it is 200 ± 100 as (N Camus et al, Phys. Rev. Lett. 108, 073003 (2012)).

Endothelial cells (EC) respond to mechanical forces such as shear stress in a variety of ways, one of which is cytoskeletal realignment in the direction of flow. Our earlier studies implicated the extracellular matrix protein fibronectin in mechanosensory signaling to ECs in intact arterioles, via a signaling pathway dependent on the heparin-binding region of the first type III repeat of fibrillar fibronectin (FNIII1H). Here we test the hypothesis that FNIII1H is required for EC stress fiber realignment under flow. Human umbilical vein ECs (HUVECs) exposed to defined flow conditions were used as a well-characterized model of this stress fiber alignment response. Our results directly implicate FNIII1H in realignment of stress fibers in HUVECs and, importantly, show that the matricryptic heparin-binding RWRPK sequence located in FNIII1 is required for the response. Furthermore, we show that flow-mediated stress fiber realignment in ECs adhered via α5β1-integrin-specific ligands does not occur in the absence of FHIII1H, whereas, in contrast, αvβ3-integrin-mediated stress fiber realignment under flow does not require FNIII1H. Our findings thus indicate that there are two separate mechanosignaling pathways mediating the alignment of stress fibers after exposure of ECs to flow, one dependent on αvβ3-integrins and one dependent on FNIII1H. This study strongly supports the conclusion that the RWRPK region of FNIII1H may have broad capability as a mechanosensory signaling site.

In microvessels, acute inflammation is typified by an increase in leukocyte-endothelial cell interactions, culminating in leukocyte transmigration into the tissue, and increased permeability to water and solutes, resulting in tissue edema. The goal of this study was to establish a method to quantify solute permeability ( Ps) changes in microvessels in intact predominantly blood-perfused networks in which leukocyte transmigratory behavior could be precisely described using established paradigms. We used intravital confocal microscopy to measure solute (BSA) flux across microvessel walls, hence Ps. A quantitative fluorescence approach (Huxley VH, Curry FE, and Adamson RH. Am J Physiol Heart Circ Physiol 252: H188–H197, 1987) was adapted to the imaged confocal tissue slice in which the fluorescent source volume and source surface area of the microvessel were restricted to the region of vessel that was contained within the imaged confocal tissue section. Ps measurements were made in intact cremaster muscle microvasculature of anesthetized mice and compared with measurements of Ps made in isolated rat skeletal muscle microvessels. Mouse arteriolar Ps was 9.9 ± 1.1 × 10−7 cm/s ( n = 16), which was not different from 8.4 ± 1.3 × 10−7 cm/s ( n = 6) in rat arterioles. Values in venules were significantly ( P < 0.05) higher: 44.4 ± 7.9 × 10−7 cm/s ( n = 14) in mice and 25.0 ± 3.7 × 10−7 cm/s in rats. Convective coupling was estimated to contribute s in both microvessel types and both animal models. We conclude that this approach provides an appropriate quantification of Ps in the intact microvasculature and that arteriolar Ps, while lower than in venules, is nevertheless consistent with arterioles being a significant source of interstitial protein.

Nonlinear absorption of femtosecond kilovolt x-rays in Neon is investigated. A possible two-photon Ionization is observed with the presence of Ne9+ at photon energies below the Ne8+ 1s2 ionization threshold.

The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated. The production of ${\mathrm{Ne}}^{9+}$ is observed at x-ray frequencies below the ${\mathrm{Ne}}^{8+}$, $1{s}^{2}$ absorption edge and demonstrates a clear quadratic dependence on fluence. Theoretical analysis shows that the production is a combination of the two-photon ionization of ${\mathrm{Ne}}^{8+}$ ground state and a high-order sequential process involving single-photon production and ionization of transient excited states on a time scale faster than the Auger decay. We find that the nonlinear direct two-photon ionization cross section is orders of magnitude higher than expected from previous calculations.

Epitaxial gadolinium nitride films with well-oriented crystallites of up to 30 nm have been grown on yttria-stabilized ziconia substrates using a plasma-assisted pulsed laser deposition technique. We observe that the epitaxial GdN growth proceeds on top of a gadolinium oxide buffer layer that forms via reaction between deposited Gd and mobile oxygen from the substrate. Hall effect measurements show the films are electron doped to degeneracy, with carrier concentrations of 4×1020 cm−3. Magnetic measurements establish a TC of 70 K with a coercive field that can be tuned from 200 Oe to as low as 10 Oe.