Pulmonary artery banding is a surgical procedure performed when there is a shunt between the left and right ventricle. Its aim is to constrict the lumen of the pulmonary artery by using a band to reduce blood flow to the lungs. In this study, we report the results of investigating the mechanical properties of a composite composed of poly(L-lactide-co-ε-caprolactone) layers and a collagen matrix (PLCL-COLL). PLCL layers were obtained by electrospinning, impregnated with collagen solution, and finally cross-linked to increase the stiffness of the material. Bands of PLCL-COLL were implanted into a rat peritoneum and explanted after 1, 3, and 6 months in vivo. The mechanical properties of the material before and after implantation were determined using uniaxial tensile tests. The same was done with samples of strips prepared from GORE-TEX material. By comparing the results of tensile tests before implantation and after explantation, it was found that PLCL-COLL degrades in the rat's body and that it exhibits a mechanical response showing of elastic modulus values that correspond well to arterial biomechanics (elastic modulus measured in the initial linear region of the deformation was found to be: 4.14 MPa ± 1.11 MPa, 2.34 MPa ± 1.02 MPa, 1.11 MPa ± 0.77 MPa, and 0.88 MPa ± 0.60 MPa before implantation, and 1, 3, and 6 months after implantation respectively). Similar to the elastic modulus, the strength of the PLCL-COLL composite decreased during in vivo exposure (1.32 ± 0.32 MPa, 0.60 ± 0.26 MPa, 0.44 ± 0.11 MPa, and 0.46 ± 0.28 MPa before implantation, and 1, 3, and 6 months after implantation respectively). In our experiments, PLCL-COLL material was always more compliant than GORE-TEX (elastic modulus 34.7 MPa ± 2.06 MPa before implantation, and 9.35 MPa ± 6.80 MPa after implantation). The results suggest that PLCL-COLL could be a suitable candidate for the development of artery banding tapes, and also for further use in cardiovascular surgery.
- MeSH
- arteria pulmonalis * chirurgie MeSH
- biokompatibilní materiály chemie MeSH
- biomechanika MeSH
- kolagen * chemie metabolismus MeSH
- krysa rodu rattus MeSH
- mechanické jevy * MeSH
- peritoneum * chirurgie MeSH
- pevnost v tahu MeSH
- polyestery * chemie metabolismus MeSH
- testování materiálů MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Various studies have correlated the mechanical properties of the aortic wall with its biochemical parameters and inner structure. Very few studies have addressed correlations with the cohesive properties, which are crucial for understanding fracture phenomena such as aortic dissection, i.e. a life-threatening process. Aimed at filling this gap, we conducted a comprehensive biochemical and histological analysis of human aortas (the ascending and descending thoracic and infrarenal abdominal aorta) from 34 cadavers obtained post-mortem during regular autopsies. The pentosidine, hydroxyproline and calcium contents, calcium/phosphorus molar ratio, degree of atherosclerosis, area fraction of elastin, collagen type I and III, alpha smooth muscle actin, vasa vasorum, vasa vasorum density, aortic wall thickness, thicknesses of the adventitia, media and intima were determined and correlated with the delamination forces in the longitudinal and circumferential directions of the vessel as determined from identical cadavers. The majority of the parameters determined did not indicate significant correlation with age, except for the calcium content and collagen maturation (enzymatic crosslinking). The main results concern differences between enzymatic and non-enzymatic crosslinking and those caused by the presence of atherosclerosis. The enzymatic crosslinking of collagen increased with age and was accompanied by a decrease in the delamination strength, while non-enzymatic crosslinking tended to decrease with age and was accompanied by an increase in the delamination strength. As the rate of calcification increased, the presence of atherosclerosis led to the formation of calcium phosphate plaques with higher solubility than the tissue without or with only mild signs of atherosclerosis. STATEMENT OF SIGNIFICANCE: This study presents a detailed biochemical and histological analysis of human aortic samples (ascending thoracic aorta, descending thoracic aorta and infrarenal abdominal aorta) taken from 34 cadavers. The contribution of this scientific study lies in the detailed biochemical comparison of the enzymatic and non-enzymatic glycosylation-derived crosslinks of vascular tissues and their influence on the delamination strength of the human aorta since, to the best of our knowledge, no such comprehensive studies exist in the literature. A further benefit concerns the notification of the limitations of the various analytical methods applied; an important factor that must be taken into account in such studies.
- MeSH
- aktiny metabolismus MeSH
- aorta * metabolismus MeSH
- arginin analogy a deriváty MeSH
- ateroskleróza metabolismus patologie MeSH
- dospělí MeSH
- elastin metabolismus MeSH
- hydroxyprolin metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- lysin analogy a deriváty metabolismus MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- stárnutí * fyziologie MeSH
- vápník metabolismus MeSH
- vasa vasorum metabolismus MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Diamond-like carbon (DLC) layers are known for their high corrosion and wear resistance, low friction, and high biocompatibility. However, it is often necessary to dope DLC layers with additional chemical elements to strengthen their adhesion to the substrate. Ti-DLC layers (doped with 0.4, 2.1, 3.7, 6.6, and 12.8 at.% of Ti) were prepared by dual pulsed laser deposition, and pure DLC, glass, and polystyrene (PS) were used as controls. In vitro cell-material interactions were investigated with an emphasis on cell adhesion, proliferation, and osteogenic differentiation. We observed slightly increasing roughness and contact angle and decreasing surface free energy on Ti-DLC layers with increasing Ti content. Three-week biological experiments were performed using adipose tissue-derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (bmMSCs) in vitro. The cell proliferation activity was similar or slightly higher on the Ti-doped materials than on glass and PS. Osteogenic cell differentiation on all materials was proved by collagen and osteocalcin production, ALP activity, and Ca deposition. The bmMSCs exhibited greater initial proliferation potential and an earlier onset of osteogenic differentiation than the ADSCs. The ADSCs showed a slightly higher formation of focal adhesions, higher metabolic activity, and Ca deposition with increasing Ti content.
PURPOSE: A new generation of CT detectors were recently developed with the ability to measure individual photon's energy and thus provide spectral information. The aim of this work was to assess the performance of simultaneous fat and iron quantification using a clinical photon-counting CT (PCCT) and its comparison to dual-energy CT (DECT), MRS and MRI at 3 T. METHODS: Two 3D printed cylindrical phantoms with 32 samples (n = 12 fat fractions between 0 % and 100 %, n = 20 with mixtures of fat and iron) were scanned with PCCT and DECT scanners for comparison. A three-material decomposition approach was used to estimate the volume fractions of fat (FF), iron and soft tissue. The same phantoms were examined by MRI (6-echo DIXON, a.k.a. Q-DIXON) and MRS (multi-echo STEAM, a.k.a. HISTO) at 3 T for comparison. RESULTS: PCCT, DECT, MRI and MRS computed FFs showed correlation with reference fat fraction values in samples with no iron (r > 0.98). PCCT decomposition showed slightly weaker correlation with FFref in samples with added iron (r = 0.586) compared to MRI (r = 0.673) and MRS (r = 0.716) methods. On the other hand, it showed no systematic over- or underestimation. Surprisingly, DECT decomposition-derived FF showed strongest correlation (r = 0.758) in these samples, however systematic overestimation was observed. FF values computed by three-material PCCT decomposition, DECT decomposition, MRI and MRS were unaffected by iron concentration. CONCLUSIONS: This in-vitro study shows for the first time that photon-counting computed tomography may be used for quantification of fat content in the presence of iron deposits.
The physical properties and structure of collagen treated with high-pressure technologies have not yet been investigated in detail. The main goal of this work was to determine whether this modern gentle technology significantly changes the properties of collagen. High pressure in the range of 0-400 MPa was used, and the rheological, mechanical, thermal, and structural properties of collagen were measured. The rheological properties measured in the area of linear viscoelasticity do not statistically significantly change due to the influence of pressure or the duration of pressure exposure. In addition, the mechanical properties measured by compression between two plates are not statistically significantly influenced by pressure value or pressure hold time. The thermal properties Ton and ∆H measured by differential calorimetry depend on pressure value and pressure hold time. Results from amino acids and FTIR analyses show that exposure of collagenous gels to high pressure (400 MPa), regardless of applied time (5 and 10 min), caused only minor changes in the primary and secondary structure and preserved collagenous polymeric integrity. SEM analysis did not show changes in collagen fibril ordering orientation over longer distances after applying 400 MPa of pressure for 10 min.
- Publikační typ
- časopisecké články MeSH
- MeSH
- fibrilace komor etiologie terapie MeSH
- lidé MeSH
- mladý dospělý MeSH
- multiorgánové selhání etiologie MeSH
- otrava rostlinami * patofyziologie terapie MeSH
- pokus o sebevraždu MeSH
- taxoidy otrava MeSH
- tis * otrava MeSH
- Check Tag
- lidé MeSH
- mladý dospělý MeSH
- Publikační typ
- kazuistiky MeSH
Aortic dissection is a biomechanical phenomenon associated with a failure of internal cohesion, which manifests itself through the delamination of the aortic wall. The goal of this study is to deepen our knowledge of the delamination strength of the aorta. To achieve this, 661 peeling experiments were carried out with strips of the human aorta collected from 46 cadavers. The samples were ordered into groups with respect to (1) anatomical location, (2) orientation of the sample, and (3) extension rate used within the experiment. The obtained results are in accordance with the hypothesis that delamination resistance is not sensitive to the extension rates 0.1, 1, 10, and 50 mms-1. We arrived at this conclusion for all positions along the aorta investigated in our study. These were the thoracic ascending (AAs), thoracic descending (ADs), and the abdominal aorta (AAb), simultaneously considering both the longitudinal (L) as well as the circumferential (C) orientations of the samples. On the other hand, our results showed that the delamination strength differs significantly with respect to the anatomical position and orientation of the sample. The medians of the delamination strength were as follows, 4.1 in AAs-L, 3.2 in AAs-C, 3.1 in ADs-L, 2.4 in ADs-C, AAb-L in 3.6, and 2.7 in AAb-C case (all values are in 0.01·Nmm-1). This suggests that resistance to crack propagation should be an anisotropic property and that the aorta is inhomogeneous along its length from the point of view of delamination resistance. Finally, correlation analysis proved that the delamination strength of the human aorta significantly decreases with age.
- MeSH
- anizotropie MeSH
- aorta abdominalis MeSH
- aorta thoracica MeSH
- biomechanika MeSH
- disekce aorty * MeSH
- lidé MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Úvod: Kardiovaskulární choroby jsou zodpovědné za významnou morbiditu i mortalitu ve společnosti. Užití umělých cévních materiálů je často nezbytnou součástí v rámci chirurgické léčby, ať již je tato radikální nebo paliativní. V současné době dochází k vývoji řady nových biodegradabilních materiálů určených pro tyto účely. Preklinické testování každého nového materiálu je naprosto nezbytné, je prováděno jak in vitro, tak in vivo. Z tohoto důvodu jsou zvířecí experimentální modely nadále nutnou součástí testování před klinickým užitím. Cílem této práce je prezentovat možnosti užití různých zvířecích modelů na poli kardiovaskulární chirurgie a jejich extrapolace do klinické medicíny. Metody: Autoři prezentují jejich obecné zkušenosti s experimentální chirurgií, na jejich podkladě diskutují optimální výběr zvířecího modelu pro testování nových materiálů pro kardiovaskulární chirurgii a stejně tak optimální lokalitu implantace. Výsledky: Jako optimální experimentální zvířecí modely pro testování hemokompatibility a degradability nových materiálů uvádějí autoři modely potkana, králíka a prasete. Intraperitoneální implantace u potkana je snadná a lehce proveditelná procedura, stejně tak jako arteriální bandáž na aortě králíka či prasete. Rovněž karotické tepny jsou dobře využitelné. Bandáž na prasečí pulmonální tepně je již složitější zákrok s četnějšími komplikacemi. Explantované bandážované cévy po předem definované době jsou vhodné pro další mechanické testování ve smyslu biomechanických analýz, např. inflačně-extenzního testu. Závěr: V posledních fázích preklinického testování nových materiálů se nelze nadále obejít bez in-vivo experimentů. Naší snahou je však striktně dodržovat koncept 3R – Replacement, Reduction a Refinement. V tomto smyslu je třeba využít co nejvíce potenciál každého zvířete tak, abychom mohli redukovat počty zvířat.
Introduction: Cardiovascular diseases are responsible for significant morbidity and mortality in the population. Artificial vascular grafts are often essential for surgical procedures in radical or palliative treatment. Many new biodegradable materials are currently under development. Preclinical testing of each new material is imperative, both in vitro and in vivo, and therefore animal experiments are still a necessary part of the testing process before any clinical use. The aim of this paper is to present the options of using various experimental animal models in the field of cardiovascular surgery including their extrapolation to clinical medicine. Methods: The authors present their general experience in the field of experimental surgery. They discuss the selection process of an optimal experimental animal model to test foreign materials for cardiovascular surgery and of an optimal region for implantation. Results: The authors present rat, rabbit and porcine models as optimal experimental animals for material hemocompatibility and degradability testing. Intraperitoneal implantation in the rat is a simple and feasible procedure, as well as aortic banding in the rabbit or pig. The carotid arteries can also be used, as well. Porcine pulmonary artery banding is slightly more difficult with potential complications. The banded vessels, explanted after a defined time period, are suitable for further mechanical testing using biomechanical analyses, for example, the inflation-extension test. Conclusion: An in vivo experiment cannot be avoided in the last phases of preclinical research of new materials. However, we try to strictly observe the 3R concept – Replacement, Reduction and Refinement; in line with this concept, the potential of each animal should be used as much as possible to reduce the number of animals.
The main goal of this study was to assess the progress of vertebral stability after lumbar interbody fusion related to microcomputed tomography (micro CT), biomechanical analysis, and histological assessment towards spine fusion. Twelve male pigs were used; each underwent L2-3 discectomy and implantation of an iliac crest bone graft in two groups; six spines were harvested eight weeks (A1) and six spines 16 weeks (A2) after surgery (7 native spines for biomechanical analysis). The CT was performed by GE phoenix datos|x 2.0 with a sample drift correction. The samples were divided according to fusion quality. Biomechanical evaluation was carried out on the MTS Mini Bionix testing system. In the nondestructive mode, three cycles of pure bending moments were applied (5 Nm load limit) at a rate of 20 °/min in flexion (+40 °) and extension (-40 °). Two representative histological sections from four samples were obtained (A1, n = 2; A2, n = 2); areas of mature bone were quantified. In micro CT, better results were achieved in group A2 (not significant). Eight weeks after the operation, flexural stiffness decreased to 48% of its initial value for native cadavers (P < 0.05); after 16 weeks it was comparable to native cadavers, demonstrating the suitability of the implanted graft (P < 0.05). The newly formed bone tissue occupied an average area of 94.205 mm2 (A1) and 26.240 mm2 (A2). It was confirmed that micro CT, biomechanical analysis, and histological assessment are technically feasible and suitable for the evaluation of results of other methods of large bone defect treatment.