Subject(s)
Attitude to Death , Catholicism , Death , Euthanasia, Active/ethics , Euthanasia, Passive/ethics , Thanatology , Brain Death/diagnosis , Consciousness , Euthanasia, Active/legislation & jurisprudence , Euthanasia, Passive/legislation & jurisprudence , Existentialism , Humans , Persistent Vegetative State , Suicide, Assisted/ethics , Suicide, Assisted/legislation & jurisprudence , Value of LifeABSTRACT
The modifications of mechanical properties produced in valvular tissue by glutaraldehyde fixation were studied. Porcine aortic leaflets, fresh and fixed with glutaraldehyde in a stressed state, were tested with a mechanical device. The results we obtained show that the fixed leaflets have a failure load higher than fresh ones and an increased elastic recovery. The time of preservation (up to one year) does not affect the mechanical properties of fixed samples. The temperature of shrinkage was also studied, and we found that fixed leaflets show no shrinkage at all.
Subject(s)
Aldehydes/pharmacology , Aortic Valve/physiology , Glutaral/pharmacology , Animals , Biomechanical Phenomena , Swine/anatomy & histology , Time Factors , Tissue Preservation/methodsABSTRACT
Treatment of porcine valves in vitro with glutaraldehyde significantly decreases their heteroantigenicity, as judged by immune reaction in mice heterografted with glutaraldehyde-treated valves or injected intraperitoneally with valvular homogenates. Conditioned porcine valves, grafted in a cutaneous pouch onto the backs of two different inbred strains (C57Bl and DBA) behave like inert material and show minimal cellular infiltration at histological examination. Little or no antibody response, demonstrate with the cytotoxicity test is elicited by glutaraldehyde-treated valvular tissue, either grafted or injected intraperitoneally as homogenate. These data supply a biological basis for the surgical practice of heterotransplants of glutaraldehyde-treated valves as an alternative to the artificial prostheses.
Subject(s)
Aldehydes/pharmacology , Antigens , Glutaral/pharmacology , Heart Valve Prosthesis , Animals , Antilymphocyte Serum , Female , Heart Valves/transplantation , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Spleen/transplantation , SwineABSTRACT
Suspensions of collagen fibrils obtained from derma of Elasmobranchia and Actinopterygia of different body sizes and developmental stages were examined by transmission electron microscopy. Fibril diameters were measured and classified into groups comprising a 20 nm diameter interval. Diagrams showing fibril populations of each fish were made. The measurements were averaged and their confidence intervals and standard errors determined. For each species other diagrams were plotted in which the mean diameters were correlated to the body length of each sample. The results show that: 1) a correlation exists between an increase in diameter of collagen fibrils and somatic growth until sexual maturity is reached; 2) fibril populations are subsequently spread over a wider range due to the presence in the derma of classes of newly formed and therefore thinner fibrils. The deposition of new fibrils is possibly influenced by individual factors; 3) no relationship exists between mean fibril diameter and body size; 4) no relationship exists between phylogenetic position and pattern of diameter distribution.
