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At least 973 records · Page 54Linked to original sources
PubMed2000

Electronmicroscopic changes in selected vital organs after long-term total artificial heart pumping in animal experiments.

Electronmicroscopic (EM) evaluation of selected vital organs (liver, kidney, lung) informs us about otherwise hardly detectable changes during total artificial heart (TAH) pumping. In our experiments, we compared 2 groups of long-surviving animals in which the TAH TNS-BRNO pneumatic device was implanted (TNS-BRNO-II and VII in 45 experiments, TNS-BRNO-III in 1 experiment, and TNS-BRNO-VIII in 1 experiment). In 4 experiments, the Rostock TAH (NABEL, TAH Research Center, Rostock, Germany) was implanted. One group of 22 animals with an average survival of 162 days (the longest, 293 days) was submitted to an antihypertensive treatment; another 1 of 29 calves with an average survival of 98 days (the longest, 173 days) was untreated. The evaluation was performed using a scale (0 to 3) based on very precisely fixed criteria. EM pathologic changes documented various stages of ischemic damage. Except for the liver, no significant difference was found between both groups, despite the substantially prolonged survival in the treated group. Very important was the general state of mitochondria, endoplasmic reticulum, and nucleus. Further, the state of glomerular podocytes in the kidney and the state of interalveolar septa and of pneumocytes constituting the air-blood barrier for gas exchange in the lungs are especially important. In some animals of both groups, the EM findings were completely normal, especially in the lung.

Animals↗
PubMed2002

Aroma quality differentiation of pyrazine derivatives using self-organizing molecular field analysis and artificial neural network.

The encoding of various aroma impressions and the distinction between different aroma qualities are unsolved problems, as differences between aroma impressions can be described only in a qualitative but not in a quantitative manner. As a consequence, classifications of various aroma qualities cannot easily be performed by standard QSAR methods. To find a proper way to encode aroma impressions for SAR studies, a total of 50 pyrazine-based aroma compounds showing the aroma quality of earthy, green-earthy, or green are analyzed. Special attention is thereby turned on the mixed aroma impression green-earthy. Classifications on the whole data set as well as on smaller subsets are calculated using self-organizing molecular field analysis (SOMFA) and artificial neural networks (ANNs). SOMFA classifies between two or three aroma impressions, leading to models satisfying in predictive power. ANN analysis using multilayer perceptron network architecture with one hidden layer and nominal output as well as genetic regression neural network) with two hidden layers and numerical output both lead to a rather good performance rate of 94%.

Neural Networks, Computer↗
PubMed2003

Organ printing: computer-aided jet-based 3D tissue engineering.

Tissue engineering technology promises to solve the organ transplantation crisis. However, assembly of vascularized 3D soft organs remains a big challenge. Organ printing, which we define as computer-aided, jet-based 3D tissue-engineering of living human organs, offers a possible solution. Organ printing involves three sequential steps: pre-processing or development of "blueprints" for organs; processing or actual organ printing; and postprocessing or organ conditioning and accelerated organ maturation. A cell printer that can print gels, single cells and cell aggregates has been developed. Layer-by-layer sequentially placed and solidified thin layers of a thermo-reversible gel could serve as "printing paper". Combination of an engineering approach with the developmental biology concept of embryonic tissue fluidity enables the creation of a new rapid prototyping 3D organ printing technology, which will dramatically accelerate and optimize tissue and organ assembly.

Artificial Organs↗
PubMed1989

Haemolysis during in vitro CO2 removal from human blood using a membrane lung.

Haemolysis of human blood has been examined in vitro as a function of pH in the range 7.2-8.0. The hydrogen ion concentration of freshly donated blood from 11 donors was manipulated in 42 experiments, entirely by altering the carbon dioxide fraction of air with which the blood was equilibrated using a membrane lung. In contrast to the known alkalaemic haemolysis which occurs in canine blood, we observed no correlation between plasma haemoglobin concentrations and blood pH. We conclude that alkalaemic haemolysis is unlikely to complicate the clinical application of extracorporeal carbon dioxide removal in the management of acute respiratory failure.

Acid-Base Equilibrium↗
PubMedDate not supplied

Factors affecting humidity of inspired gas in a neonatal lung model.

OBJECTIVE: The American National Standards Institute recommends an absolute humidity of > or = 30 mg/L of inspired gas in patients receiving mechanical ventilation. This study was designed to assess the absolute humidity of inspired gas in relation to humidifier settings and environmental conditions in a test lung. STUDY DESIGN: Measurements were obtained at the endotracheal tube manifold of an artificial lung in an isolette or radiant warmer with use of a nonheated wired system and two different ventilator circuit lengths. Temperature and relative humidity were measured at three environmental temperatures and various humidifier settings. RESULTS: We achieved adequate absolute humidity levels only at near maximum humidifier settings. When the artificial lung was placed in an isolette with a standard circuit length inside the isolette, adequate absolute humidity was never reached at an environmental temperature of 30 degrees C. Increasing the length of the ventilator circuit situated inside the isolette or using a radiant warmer improved absolute humidity compared with that obtained with use of a standard circuit length. CONCLUSION: Recommended absolute humidity levels may not be reached at the manifold even at high humidifier settings. Thus actual measurements of relative humidity and temperature at the endotracheal tube site are necessary to optimize humidity according to American National Standards Institute recommendations.

Artificial Organs↗
PubMed2006

Fabrication of endothelialized tube in collagen gel as starting point for self-developing capillary-like network to construct three-dimensional organs in vitro.

A possible strategy for creating three-dimensional (3D) tissue-engineered organs in vitro with similar volumes to the primary organs is to develop a capillary network throughout the constructs to provide sufficient oxygenation and nutrition to the cells composing them. Here, we propose a novel approach for the creation of a capillary-like network in vitro, based on the spontaneous tube-forming activity of vascular endothelial cells (ECs) in collagen gel. We fabricated a linear tube of 500 microm in diameter, the inner surface of which was filled with bovine carotid artery vascular endothelial cells (BECs), in type I collagen gel as a starting point for the formation of a capillary-like network. The BECs exposed to a medium containing vascular endothelial growth factor (VEGF) migrated into the ambient gel around the tube. After 2 weeks of VEGF exposure, the distance of the migration into the ambient gel in the radial direction of the tube reached approximately 800 microm. Cross-sections of capillary-like structures composed of the migrating BECs, with a lumen-like interior space, were observed in slices of the gel around the tube stained with hematoxylin-eosin (H&E). These results demonstrate that this approach using a pre-established tube, which is composed of ECs, as a starting point for a self-developing capillary-like network is potentially useful for constructing 3D organs in vitro.

Animals↗