6 research outputs found
Fibroblast Growth Factor Signaling Mediates Pulmonary Endothelial Glycocalyx Reconstitution
The endothelial glycocalyx is a heparan sulfate (HS)-rich endovascular structure critical to endothelial function. Accordingly, endothelial glycocalyx degradation during sepsis contributes to tissue edema and organ injury. We determined the endogenous mechanisms governing pulmonary endothelial glycocalyx reconstitution, and if these reparative mechanisms are impaired during sepsis. We performed intravital microscopy of wild-type and transgenic mice to determine the rapidity of pulmonary endothelial glycocalyx reconstitution after nonseptic (heparinase-III mediated) or septic (cecal ligation and puncture mediated) endothelial glycocalyx degradation. We used mass spectrometry, surface plasmon resonance, and in vitro studies of human and mouse samples to determine the structure of HS fragments released during glycocalyx degradation and their impact on fibroblast growth factor receptor (FGFR) 1 signaling, a mediator of endothelial repair. Homeostatic pulmonary endothelial glycocalyx reconstitution occurred rapidly after nonseptic degradation and was associated with induction of the HS biosynthetic enzyme, exostosin (EXT)-1. In contrast, sepsis was characterized by loss of pulmonary EXT1 expression and delayed glycocalyx reconstitution. Rapid glycocalyx recovery after nonseptic degradation was dependent upon induction of FGFR1 expression and was augmented by FGF-promoting effects of circulating HS fragments released during glycocalyx degradation. Although sepsis-released HS fragments maintained this ability to activate FGFR1, sepsis was associated with the downstream absence of reparative pulmonary endothelial FGFR1 induction. Sepsis may cause vascular injury not only via glycocalyx degradation, but also by impairing FGFR1/EXT1-mediated glycocalyx reconstitution
Detection of Phenol and Benzoate as Intermediates of Anaerobic Benzene Biodegradation under Different Terminal Electron-Accepting Conditions
Impact of Photooxidation and Biodegradation on the Fate of Oil Spilled During the Deepwater Horizon Incident: Advanced Stages of Weathering
While
the biogeochemical forces influencing the weathering of spilled
oil have been investigated for decades, the environmental fate and
effects of “oxyhydrocarbons” in sand patties deposited
on beaches are not well-known. We collected sand patties deposited
in the swash zone on Gulf of Mexico beaches following the Deepwater
Horizon oil spill. When sand patties were exposed to simulated sunlight,
a larger concentration of dissolved organic carbon was leached into
seawater than the corresponding dark controls. This result was consistent
with the general ease of movement of seawater through the sand patties
as shown with a <sup>35</sup>SO<sub>4</sub><sup>2–</sup> radiotracer.
Ultrahigh-resolution mass spectrometry, as well as optical measurements
revealed that the chemical composition of dissolved organic matter
(DOM) leached from the sand patties under dark and irradiated conditions
were substantially different, but neither had a significant inhibitory
influence on the endogenous rate of aerobic or anaerobic microbial
respiratory activity. Rather, the dissolved organic photooxidation
products stimulated significantly more microbial O<sub>2</sub> consumption
(113 ± 4 μM) than either the dark (78 ± 2 μM)
controls or the endogenous (38 μM ± 4) forms of DOM. The
changes in the DOM quality and quantity were consistent with biodegradation
as an explanation for the differences. These results confirm that
sand patties undergo a gradual dissolution of DOM in both the dark
and in the light, but photooxidation accelerates the production of
water-soluble polar organic compounds that are relatively more amenable
to aerobic biodegradation. As such, these processes represent previously
unrecognized advanced weathering stages that are important in the
ultimate transformation of spilled crude oil