Copper and iron interactions with angiotensin-converting enzyme inhibitors. A study by fast-atom bombardment tandem mass spectrometry

Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd.     

Impact of correlation structure on drainage in open rough walled fractures

The spatial correlation structure of heterogeneous parameters plays an important role in upscaling of many flow and transport processes in porous media and fractures. We analyze upscaling of a slow drainage process in a horizontal open rough walled fracture. The applicability of upscaled continuum models for this kind of flow process is discussed. We consider two different fracture aperture distributions with different spatial correlation properties. One is described by a slowly decaying, the other one by a Gaussian autocovariance. The flow process is modelled using an invasion percolation model, which takes the in plane curvature of the fluid cluster into account. Results are compared to laboratory experiments in artificial plexiglas fractures. Different averaging procedures are tested in order to assess the applicability of continuum models. Independently of the correlation structure of the fracture aperture field, spatial averages do not converge to a continuum formulation. Ensemble averages do converge, however, they only give probabilistic information and are not applicable to model drainage in a fracture.     

General derivation of the total electromagnetic cross sections for an arbitrary particle

This work concerns a common problem in electromagnetic scattering; calculation of the total scattering, extinction, and absorption cross sections for an arbitrary particle. Typical expressions for the cross sections are obtained in terms of the vector spherical wave function expansions for the incident and scattered waves. The unique aspect of this work is that the derivation is carried out specifically without use of the far-field zone approximation. The resulting expressions, valid at any distance, exactly match those obtained from the far-field approximation. This demonstrates that the cross sections are independent of the distance from the particle at which they are calculated as one would expect from energy conservation. Numerical simulations of the near and far-field zone energy flows due to a spherical particle are presented to illustrate several implications of this result.     

Shear history independence in colloidal aggregation

Stimulated by experiments, we have carried out detailed simulations of aggregation in the presence of shear in a model colloidal system with a short-range attractive potential. For weak shear rates, we find that the shear enhanced the aggregation and that the long-time state of the system is independent of the shear history. For strong shear rates, precipitous fragmentation occurred after the shear was turned on and, after an induction period, the aggregation quickly rebounded in a stochastic manner similar to classical nucleation phenomena. However, the long-time state of the system is, once again, independent of the shear history. Thus, for both weak and strong shear cases, the shear rate acts as a state variable of the aggregating system. Shear rates employed in the simulations can be attained in laboratory experiments, as confirmed by computing the dimensionless Péclet numbers.     

Proteome Analysis of Aflibercept Intervention in Experimental Central Retinal Vein Occlusion

Aflibercept is a frequently used inhibitor of vascular endothelial growth factor (VEGF) in the treatment of macular edema following central retinal vein occlusion (CRVO). Retinal proteome changes following aflibercept intervention in CRVO remain largely unstudied. Studying proteomic changes of aflibercept intervention may generate a better understanding of mechanisms of action and uncover aspects related to the safety profile. In 10 Danish Landrace pigs, CRVO was induced in both eyes with an argon laser. Right eyes were treated with intravitreal aflibercept while left control eyes received isotonic saline water. Retinal samples were collected 15 days after induced CRVO. Proteomic analysis by tandem mass tag-based mass spectrometry identified a total of 21 proteins that were changed in content following aflibercept intervention. In retinas treated with aflibercept, high levels of aflibercept components were reached, including the VEGF receptor-1 and VEGF receptor-2 domains. Fold changes in the additional proteins ranged between 0.70 and 1.19. Aflibercept intervention resulted in a downregulation of pigment epithelium-derived factor (PEDF) (fold change = 0.84) and endoplasmin (fold change = 0.91). The changes were slight and could thereby not be confirmed with less precise immunohistochemistry and Western blotting. Our data suggest that aflibercept had a narrow mechanism of action in the CRVO model. This may be an important observation in cases when macular edema secondary to CRVO is resistant to aflibercept intervention.     

Magnetic properties of aerosol synthesized iron oxide particles

Fine iron oxide particles have been prepared by an aerosol technique. The particles are spherical with a mean size of 0.1 μm. Heat treatment in air or nitrogen at various temperatures for various times leads to a variety of phase mixtures of -Fe₂O₃, γ-Fe₂O₃ and Fe₃O₄. The magnetic properties of these various samples are presented.