Characterization of aneurysmal aortas by biochemical, thermal, and dielectric techniques

Abstract

Abdominal aortic aneurysms (AAA) are characterized by structural alterations of the aortic wall resulting from the degradation of elastic fibres and an increase of collagen/elastin ratio. In this study we investigated the chain dynamics of AAA tissues by two techniques generally used for the characterization of polymers, Differential scanning calorimetry (DSC) and thermally stimulated currents (TSC), and we correlated the obtained data with biochemical analyses. The thermal denaturation of collagen observed by DSC allowed us to evaluate the thermal stability of the triple helix domain: notable modifications were evidenced between collagen from control tissue and collagen from AAA, particularly concerning the thermal denaturation. The dielectric analysis of pathologic aortic walls by TSC revealed a relevant change of collagen mobility in AAA, with the occurrence of a specific mode of relaxation between -60 and -40°C. Biochemical, thermal, and dielectric results are compatible with increase of new collagen deposition and/or impairment of the collagen phase stability in the extracellular matrix of AAAs.

Stability of peritoneal tissue evaluated by the means of DSC in obese patients undergoing laparoscopic cholecystectomy

“…In our samples, the denaturation endotherm was followed by an equilibrium state adequate to the new configuration of the protein molecules at temperatures just above 70°C. Similar values of denaturation temperatures are reported for samples from other collagenbased tissues [8,10,22,23]. Thermal stability of collagen molecules reflects the overall condition of the structure, cross-links in the collagen network, and its interactions with the surrounding molecules [4,21,[24][25][26].…”

“…The DSC method has proven to be a valuable tool in assessing the role of collagen in structural alterations of several cardiovascular and musculoskeletal diseases [8][9][10][11]. Our previous study showed that DSC was the appropriate method for investigation of subtle changes in physicochemical conditions of peritoneum using tissues obtained during surgical procedures [12].…”

The Use of Thermal Techniques for the Characterization and Selection of Natural Biomaterials

“…Considering that the valvular leaflet contains 70% of collagen and only 6% of elastin, it is coherent to observe only the thermal signature of collagen in this kind of tissues. A previous work showed a strong analogy between the thermograms of human valvular leaflet and porcine valvular leaflet, confirming the ability of porcine bioprostheses to replace human aortic valves at a molecular level [35,36]. …”

Identification of new biophysical markers for pathological ventricular remodelling in tachycardia‐induced dilated cardiomyopathy

“…Differential scanning calorimetry (DSC) is another suitable technique for characterizing biological tissues at the mesoscale, evaluating freezable and unfreezable water and assessing protein thermal stability and conformational changes in tissues . DSC is particularly appropriate for evaluating the thermal stability of collagen in its purified or aggregated form, directly in cardiovascular tissues or in biomaterials . DSC has been also successfully applied to characterize the protein components of muscle tissues, such as myosin and its subfragments, actin and sarcoplasmic proteins .…”