Impact of the Incubation Medium on the Endothelium of Autologous Vein Grafts: Damage Scoring by Scanning Electron Microscopy

The aim of this study was to examine the influence of different incubation media on the morphology of the endothelium of great saphenous vein grafts and establish a suitable scoring system for the evaluation of damage caused by these media. Fifty specimens of saphenous veins from ten patients during elective aorto-coronary bypass surgery were used. Ten specimens served as controls; the others were assigned to test groups and exposed to heparinized whole blood, Bretschneider\u27s HTK, human albumin or Ringer\u27s solution. Specimens exposed to heparinized blood showed only slight morphological alterations, whereas the other three mediums caused severe damage. Thus, heparinized blood seems to be most suitable as a rinsing and incubation medium. A widely accepted scoring system for the quantification of endothelial damage caused by the incubation media did not adequately reflect the morphological alterations in the cytoskeleton and membrane topology. The proposed scoring system, which is based on endothelial cell separation, endothelial cell loss, amount of deposits, endothelial cell surface homogeneity, in addition to the frequency of spikes and blebs, seems to be suitable for characterizing differences in endothelial morphology

Broadband Dielectric Spectroscopy on Human Blood

Dielectric spectra of human blood reveal a rich variety of dynamic processes. Achieving a better characterization and understanding of these processes not only is of academic interest but also of high relevance for medical applications as, e.g., the determination of absorption rates of electromagnetic radiation by the human body. The dielectric properties of human blood are studied using broadband dielectric spectroscopy, systematically investigating the dependence on temperature and hematocrit value. By covering a frequency range from 1 Hz to 40 GHz, information on all the typical dispersion regions of biological matter is obtained. We find no evidence for a low-frequency relaxation (alpha-relaxation) caused, e.g., by counterion diffusion effects as reported for some types of biological matter. The analysis of a strong Maxwell-Wagner relaxation arising from the polarization of the cell membranes in the 1-100 MHz region (beta-relaxation) allows for the test of model predictions and the determination of various intrinsic cell properties. In the microwave region beyond 1 GHz, the reorientational motion of water molecules in the blood plasma leads to another relaxation feature (gamma-relaxation). Between beta- and gamma-relaxation, significant dispersion is observed, which, however, can be explained by a superposition of these relaxation processes and is not due to an additional delta-relaxation often found in biological matter. Our measurements provide dielectric data on human blood of so far unsurpassed precision for a broad parameter range. All data are provided in electronic form to serve as basis for the calculation of the absorption rate of electromagnetic radiation and other medical purposes. Moreover, by investigating an exceptionally broad frequency range, valuable new information on the dynamic processes in blood is obtained.Comment: 17 pages, 9 figure

Protein kinase C isoenzymes in rat and human cardiovascular tissues

1. We have compared the expression of protein kinase C (PKC) activity and immuno-detectable isoenzymes in cytosolic and membrane extracts of rat and human cardiovascular tissues (heart, kidney, aorta, saphenous vein). Experiments were performed in raw extracts and upon combined diethylaminoethylcellulose (DEAE) and phenylsepharose column chromatography. 2. PKC activity that bound to DEAE mostly eluted with 200 mM NaCl. DEAE-purified PKC from all tissues except rat kidney bound almost quantitatively to phenylsepharose and eluted with 0.5–0 M NaCl. 3. Immunoblots with an antibody against classical PKCs and the activator profile for phosphatidylserine, diolein and Ca(2+) revealed that the PKC from rat kidney, which did not bind to phenylsepharose, was most probably due to a proteolytically-generated, constitutively active PKC which is not under the control of a regulatory subunit. 4. Studies in the reference tissue, rat brain, demonstrated that all PKC isoenzymes investigated (classical PKCs α, β, γ, new PKCs δ, ε, ζ, θ, and atypial PKCs ζ, λ, ι) have similar DEAE and phenylsepharose chromatography elution profiles. In the functional assay an inhibitor of all known PKC isoenzymes, bisindolylmaleimide, and a specific inhibitor of classical PKCs, Gö 6976, both inhibited PKC from rat brain completely and with high potency indicating that the functional assay preferentially detects classical PKC isoenzymes. 5. Each PKC isoenzyme had a tissue-specific expression profile which was similar in rat and man. The classical PKCα, the new PKCs δ and ε and all atypical PKCs were detectable in most tissues, whereas the PKCβ and PKCγ were not detected in any pheripheral tissue; PKCζ and PKCθ were found in some tissues. 6. We conclude that combined DEAE and phenylsepharose chromatography is useful to enrich and detect PKC isoenzymes; no major species differences in tissues-specific expression patterns appear to exist between rat and man

Detailed study of the dielectric function of a lysozyme solution studied with molecular dynamics simulations

The spread of microwave technology and new microwave applications in medicine have revitalized interest in the dielectric behavior of biological systems. In this work, the Fröhlich–Kirkwood approach and the linear response theory have been applied in conjunction with molecular dynamics simulations to study the dielectric response of a lysozyme solution as a model. The overall experimental dielectric behavior of a 9.88 mM lysozyme solution has been reproduced in a quantitative manner by employing a method based on the decomposition of the hydration shells close to the solute. Detailed analysis of the calculated spectra identified two δ-processes located at 200 MHz (δ1) and about 1 GHz (δ2), respectively. δ1 is associated mainly with the first hydration shell, while δ2 mainly with bulk water and the second hydration shell. Moreover, indications for the existence of an even faster relaxation in the 1011-Hz frequency range were found for the first time. Finally, the static dielectric constants of lysozyme and its first and second hydration shells were calculated based on the Fröhlich–Kirkwood and the linear response theory approaches. © 2015 European Biophysical Societies' Associatio