Human heart valve allografts mechanical and morphological properties according to duration of tissue cryopreservation

Cíle: Jedním ze způsobů náhrady semilunárních chlopní je transplantace lidských alograftů srdečních chlopní (ASCH). Aortální a pulmonální ASCH jsou skladovány v kryobance chlopenních štěpů. Exspirační doba kryoprezervovaných chlopenních štěpů byla arbitrárně stanovena na 5 let. Cílem dizertační práce bylo ověření hypotézy, že ASCH ani po 5 letech skladování v tekutém dusíku neztrácejí své příznivé mechanické a strukturální vlastnosti. Materiál a metody: Z celkového počtu 64 lidských ASCH (31 aortálních a 33 pulmonálních) různé délky kryoprezervace (čerstvých, do 5 let, 5-10 let a více než 10 let) byly odebrány vzorky tepenné stěny, cípů, ventrikulo-arteriální junkce a arteriálních ringů. Všechny vzorky byly podrobeny mechanickému testování na trakčním stroji, dokud nedošlo k narušení jejich integrity. Histologické zpracování hodnotilo podíl kolagenu a elastinu ve vzorcích přilehlé tkáně. Získané hodnoty prošly statistickým zpracováním. Výsledky: U aortálních ASCH nedošlo k významným změnám schopnosti deformovat se při působení tahu ani při kryoprezervaci ani v průběhu 10letého skladování v tekutém dusíku. Síla nutná k natržení aortální stěny nebo cípu, byla ve všech skupinách kryoprezervovaných vzorků do 10 let skladování podobná. V případě pulmonálních ASCH byla u vzorků stěn ve skupině s délkou...Background: The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not reasonably deteriorate after this period. Methods: A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction, arterial ring) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. Results: In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of...Klinika kardiovaskulární chirurgieDepartment of Cardiovascular Surgery2. lékařská fakultaSecond Faculty of Medicin

Solution conformation of the major adduct between the carcinogen (+)-anti-benzo[ɑ]pyrene diol epoxide and DNA

We have synthesized, separated, and purified ≈10 mg of a deoxyundecanucleotide duplex containing a single centrally positioned covalent adduct between (+)-anti-benzo[a]pyrene (BP) diol epoxide and the exocyclic amino group of guanosine. Excellent proton NMR spectra are observed for the (+)-trans-anti-BP diol epoxide-N^2-dG adduct positioned opposite dC and flanked by G.C pairs in the d[C1-C2-A3-T4-C5-(BP)G6-C7-T8-A9-C10-C11].d[12- G13-T14-A15-G16-C17-G18-A19-T20-G 21-G22] duplex +ADdesignated (BP)G.C 11-mer+BD. We have determined the solution structure centered about the BP covalent adduct site in the (BP)G.C 11-mer duplex by incorporating intramolecular and intermolecular proton-proton distance bounds deduced from the NMR data sets as constraints in energy minimization computations. The BP ring is positioned in the minor groove and directed toward the 5' end of the modified strand. One face of the BP ring of (BP)G6 is stacked over the G18 and A19 sugar-phosphate backbone on the partner strand and the other face is exposed to solvent. A minimally perturbed B-DNA helix is observed for the d[T4-C5-(BP)G6-C7-T8].d[A15-G16-C17-G18-A19] segment centered about the adduct site with Watson-Crick alignment for both the (BP)G6.C17 pair and flanking G.C pairs. A widening of the minor groove at the adduct site is detected that accommodates the BP ring whose long axis makes an angle of ≈45° with the average direction of the DNA helix axis. Our study holds future promise for the characterization of other steroisomerically pure adducts of BP diol epoxides with DNA to elucidate the molecular basis of structure-activity relationships associated with the stereoisomer-dependent spectrum of mutational and carcinogenic activities

Monitoring DNA–Ligand Interactions in Living Human Cells Using NMR Spectroscopy

International audienceStudies on DNA−ligand interactions in the cellular environment are problematic due to the lack of suitable biophysical tools. To address this need, we developed an in-cell NMR-based approach for monitoring DNA−ligand interactions inside the nuclei of living human cells. Our method relies on the acquisition of NMR data from cells electroporated with preformed DNA−ligand complexes. The impact of the intracellular environment on the integrity of the complexes is assessed based on in-cell NMR signals from unbound and ligand-bound forms of a given DNA target. This technique was tested on complexes of two model DNA fragments and four ligands, namely, a representative DNA minor-groove binder (netropsin) and ligands bindin

Human heart valve allografts mechanical and morphological properties according to duration of tissue cryopreservation

Background: The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not reasonably deteriorate after this period. Methods: A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction, arterial ring) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. Results: In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of..

Evaluation of the technical state of existing sewerage system in town district Ostrava-Svinov, part I

Import 11/07/2007Prezenční546 - Institut environmentálního inženýrstv

Production effect of various feeds on two size classes of juvenile tench (Tinca tinca) under the conditions of intensive rearing

The experimental rearing of tench (Tinca tinca) juveniles of two size classes with initial individual weight of 0.8 and 1.2 g was performed into flow-through aquaria connected to recirculation system during a period of 63 days. Three feeds (KARPICO Supreme 7 Ex, ASTA 2, L05/CH) with nutrient content of 37/8, 42/7 and 35/7 (% proteins/ fat) were used in the experiment. Achieved values of production indicators – feed conversion ratio (FCR) and specific growth rate (SGR) ranged from 1.84 to 4.15 and from 0.70 to 1.49 %.d–1, respectively in relationship to the size class and feed used. More favourable values were achieved with the bigger size class regardless to the diet used (FCR 1.84–3.53 and SGR 0.83–1.49 %.d–1) and the best results were achieved when using ASTA 2 feed (2.05 and 1.84 or more precisely 1.36 and 1.49%.d–1)

Impact of nucleic acid self-alignment in a strong magnetic field on the interpretation of indirect spin-spin interactions

Heteronuclear and homonuclear direct (D) and indirect (J) spin-spin interactions are important sources of structural information about nucleic acids (NAs). The Hamiltonians for the D and J interactions have the same functional form; thus, the experimentally measured apparent spin-spin coupling constant corresponds to a sum of J and D. In biomolecular NMR studies, it is commonly presumed that the dipolar contributions to Js are effectively canceled due to random molecular tumbling. However, in strong magnetic fields, such as those employed for NMR analysis, the tumbling of NA fragments is anisotropic because the inherent magnetic susceptibility of NAs causes an interaction with the external magnetic field. This motional anisotropy is responsible for non-zero D contributions to Js. Here, we calculated the field-induced D contributions to 33 structurally relevant scalar coupling constants as a function of magnetic field strength, temperature and NA fragment size. We identified two classes of Js, namely 1JCH and 3JHH couplings, whose quantitative interpretation is notably biased by NA motional anisotropy. For these couplings, the magnetic field-induced dipolar contributions were found to exceed the typical experimental error in J-coupling determinations by a factor of two or more and to produce considerable over- or under-estimations of the J coupling-related torsion angles, especially at magnetic field strengths >12 T and for NA fragments longer than 12 bp. We show that if the non-zero D contributions to J are not properly accounted for, they might cause structural artifacts/bias in NA studies that use solution NMR spectroscopy

Mechanické vlastnosti lidských aortálních a pulmonárních alograftů se během prvních deseti let kryoprezervace nemení

Cíle: Jedním ze způsobů náhrady semilunárních chlopní je transplantace lidských alograftů srdečních chlopní (ASCH). Aortální a pulmonální ASCH jsou skladovány v kryobance chlopenních štěpů. Exspirační doba kryoprezervovaných chlopenních štěpů byla arbitrárně stanovena na 5 let. Cílem práce bylo ověření hypotézy, že ASCH ani po 5 letech skladování v tekutém dusíku neztrácejí své příznivé mechanické a strukturální vlastnosti. Materiál a metody: Z celkového počtu 64 lidských ASCH (31 aortálních a 33 pulmonálních) různé délky kryoprezervace (čerstvých, do 5 let, 5-10 let a více než 10 let) byly odebrány vzorky tepenné stěny, cípů, ventrikulo-arteriální junkce a arteriálních ringů. Všechny vzorky byly podrobeny mechanickému testování na trakčním stroji, dokud nedošlo k narušení jejich integrity. Histologické zpracování hodnotilo podíl kolagenu a elastinu ve vzorcích přilehlé tkáně. Získané hodnoty prošly statistickým zpracováním. Výsledky: U aortálních ASCH nedošlo k významným změnám schopnosti deformovat se při působení tahu ani při kryoprezervaci ani v průběhu 10letého skladování v tekutém dusíku. Síla nutná k natržení aortální stěny nebo cípu, byla ve všech skupinách kryoprezervovaných vzorků do 10 let skladování podobná. V případě pulmonálních ASCH byla u vzorků stěn ve skupině s délkou kryoprezervace 5-10 let zachycena nižší schopnost deformace. Mezní napětí se však pro všechny vzorky pulmonálních ASCH (včetně stěn) mezi jednotlivými skupinami do 10 let kryoprezervace nelišilo. Změny v zastoupení kolagenu I a elastinu ve vzorcích o různé délce kryoprezervace nekorelovaly s jejich mechanickými vlastnostmi. Závěr: Potvrdili jsme hypotézu, že kryoprezervované ASCH neztrácejí ani po 5 letech skladování v tekutém dusíku své zásadní mechanické a strukturální vlastnosti. Závěr výzkumu bude aplikován do provozu tkáňové banky, umožní prodloužení doby exspirace ASCH.Background: The aortic and pulmonary allograft heart valves (AHV) are used in the cardiac surgery for replacing the impaired semilunar valves. They are harvested from donor hearts and cryostored in tissue banks. The expiration period was set to 5 years arbitrarily. We hypothesized that their mechanical and structural properties do not deteriorate after this period. Methods: A total of 64 human AHV (31 aortic and 33 pulmonary) of different length of cryopreservation (fresh, 0-5, 5-10, over 10 years) were sampled to different tissue strips (artery, leaflet, ventriculo-arterial junction) and tested by tensile test with loading velocity 10 mm/min until tissue rupture. Neighbouring regions of tissue were processed histologically and evaluated for elastin and collagen area fraction. The results were evaluated statistically. Results: In aortic AHV, the physical deformation response of wall samples to stress did not changed significantly neither during the process of cryopreservation nor during the first 10 years of storage. In pulmonary AHV, the ultimate strain dropped after 5 years of cryopreservation indicating that pulmonary artery was significantly less deformable at the time of rupture. On the other hand, the ultimate stress was equal during the first 10 years of cryostorage. The changes in collagen and elastin amount in the tissue samples were not associated with mechanical impairment. Conclusion: Neither elasticity, stiffness and solidity nor morphology of aortic and pulmonary AHV did not change reasonably with cryopreservation and in the first 10 years of cryostorage. This evidence suggests that the expiration period might be extended in the future