Loss of DPP4 activity is related to a prothrombogenic status of endothelial cells: implications for the coronary microvasculature of myocardial infarction patients

Pro-coagulant and pro-inflammatory intramyocardial (micro)vasculature plays an important role in acute myocardial infarction (AMI). Currently, inhibition of serine protease dipeptidyl peptidase 4 (DPP4) receives a lot of interest as an anti-hyperglycemic therapy in type 2 diabetes patients. However, DPP4 also possesses anti-thrombotic properties and may behave as an immobilized anti-coagulant on endothelial cells. Here, we studied the expression and activity of endothelial DPP4 in human myocardial infarction in relation to a prothrombogenic endothelial phenotype. Using (immuno)histochemistry, DPP4 expression and activity were found on the endothelium of intramyocardial blood vessels in autopsied control hearts (n = 9). Within the infarction area of AMI patients (n = 73), this DPP4 expression and activity were significantly decreased, coinciding with an increase in Tissue Factor expression. In primary human umbilical vein endothelial cells (HUVECs), Western blot analysis and digital imaging fluorescence microscopy revealed that DPP4 expression was strongly decreased after metabolic inhibition, also coinciding with Tissue Factor upregulation. Interestingly, inhibition of DPP4 activity with diprotin A also enhanced the amount of Tissue Factor encountered and induced the adherence of platelets under flow conditions. Ischemia induces loss of coronary microvascular endothelial DPP4 expression and increased Tissue Factor expression in AMI as well as in vitro in HUVECs. Our data suggest that the loss of DPP4 activity affects the anti-thrombogenic nature of the endothelium

Thermal accommodation coefficients for laser-induced incandescence sizing of metal nanoparticles in monatomic gases

The capabilities of time-resolved laser-induced incandescence (TiRe-LII), a combustion diagnostic used almost exclusively to measure soot primary particles, could potentially be extended to size aerosolized metal nanoparticles. In order to do this, however, it is necessary to characterize the thermal accommodation coefficient, a, which specifies the heat conduction rate between the laser-energized nanoparticles and the surrounding gas. This paper extends a molecular dynamics (MD) methodology to calculate a for Fe/He, Fe/Ar, Mo/He, and Mo/Ar systems. A comparative analysis of the results shows that a is most strongly influenced by the potential well between the gas molecule and nanoparticle surface. Finally, the MD-derived value for a is used to recover the nanoparticle size distribution for TiRe-LII measurements made on molybdenum nanoparticles in argon

Morphology and size of soot from gas flares as a function of fuel and water addition

A large-scale, laboratory turbulent diffusion flame was used to study the effects of fuel composition on soot size and morphology. The burner and fuels are typical of those used in the upstream oil and gas industry for gas flaring, a practice commonly used to dispose of excess gaseous hydrocarbons. Fuels were characterized by their carbon-to-hydrogen ratio (from 0.264 to 0.369) and their volumetric higher heating value (HHVv) (from 35.8 to 75.2 MJ/m3). Transmission electron microscopy (TEM) was used to assess primary particle and aggregate size, showing that the scaling of primary particle size to aggregate size was roughly the same for all of the considered fuels (dp = 16.3(da,100 [nm]/100)0.35). However, fuels with higher HHVv produced substantially larger soot aggregates. A scanning mobility particle sizer (SMPS) was also used (i) to measure mobility diameter distributions and (ii) in tandem with a centrifugal particle mass analyzer (CPMA) to determine the two-dimensional mass-mobility and effective density-mobility distributions using a new inversion approach. The new approach was shown to improve internal consistency of inferred morphological parameters, though with a shift relative to median-based analysis of the tandem data. Raman spectroscopy was used to quantify the degree of graphitization in the soot nanostructure. The addition of water to the fuel consistently reduced the soot yields but did not affect other morphological parameters. Larger aggregates also tended to have larger primary particles and higher Raman D/G ratios suggesting larger graphitic domains

Using two-dimensional distributions to inform the mixing state of soot and salt particles produced in gas flares

Gas flaring is a common practice in the oil and gas industry, where droplets of flowback water with varying levels of dissolved salts (mainly composed of sodium and chloride) often become entrained in the flared gas. In this study, we examine the mixing state of the aerosol produced by a laboratory flare with and without entrained droplets of sodium chloride solutions. The resultant aerosol is cross-examined using several different methods, including: transmission electron microscopy (TEM), tandem measurements using a CPMA and a differential mobility analyzer (DMA), tandem measurements using a centrifugal particle mass analyzer (CPMA) and a single particle soot photometer (SP2), and Raman spectroscopy. A focus is placed on two-dimensional distributions of properties and the kind of morphological information contained therein. The TEM and CPMA-SP2 measurements both show that the majority of soot particles were internally mixed with salt, while TEM and CPMA-DMA measurements indicate that there are also a large number of isolated salt particles