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At least 901 records · Page 50Linked to original sources
PubMed2000

The prosthetic ureter.

Ureteral replacement has always been a challenge. Two approaches have been explored: in situ augmentation or replacement and extra-anatomic passage of a conduit. An in-situ prosthetic ureter is basically a simple al. loplastic tube connected to the urinary tract by end-to-end sutures or by intubation and closure. Antireflux devices and peristaltic mechanisms are not necessary. Among the in-situ designs, only those composed of silicone and silicone rubber have performed at all well. Tissue engineering and acellular matrix grafts have produced impressive early results. Subcutaneous ureteral replacement with alloplasts, including a coaxial assembly of an inner silicone and outer expanded polytetrafluoroethylene tube, has produced good results. In the future, we are likely to see bioengineered neotissue combined with highly porous and infection-resistant alloplasts to create better and more functional neo-organs.

Animals↗
PubMed1992

Cell growth on collagen: a review of tissue engineering using scaffolds containing extracellular matrix.

Collagen has been used as a substrate for growth of cells derived from skin and cardiovascular tissue. Experimental results reported in the literature suggest that cell differentiation and orientation is enhanced in the presence of collagen. Extensive progress in cultivation of autogenous and allogeneic cells in vitro on collagen has led to advances in the transplantation of cultured materials. The purpose of this paper is to review the literature regarding cell culture on collagen substrates and to analyze the state of knowledge concerning the long-term effects. In the area of skin, long-term replacement of tissue has been studied extensively. Progress in this area has led to the development of technologies that will be used in the future for producing replacements for a wide variety of tissues and organs.

Animals↗
PubMed1978

The promise of the membrane artificial lung.

Membrane lungs are more physiologic than bubble or disc blood oxygenators. Membrane lungs are indispensable in long term perfusions. Recently, there has been a noticeable trend toward use of the membrane lung in open heart surgery. Improper use of the membrane lung lowers its optimum potential and may lead to disenchantment on the part of the user. It is important to recognize that for optimum performance of the membrane lung it is necessary to learn to correctly use the membrane lung.

Artificial Organs↗
PubMed1998

Recent advances in the surgical treatment of faecal incontinence.

BACKGROUND: Improved imaging and refined technology have led to a number of recent advances in the surgical treatment of faecal incontinence. METHODS: Original articles, identified using a computer database (Medline), and recently published abstracts of meetings were selected on the basis of greatest clinical relevance; these were reviewed. RESULTS: Ultrasonographic characterization has led to improved therapeutic strategies. Simple structural damage is readily identified and external sphincter repair results in a good outcome for a majority of patients. For more complex structural damage, or for the newly recognized primary internal sphincter degeneration, alternative treatment strategies are emerging. The electrically stimulated gracilis neosphincter and the artificial bowel sphincter offer good results. The latter may be a more simple operation. For structurally intact but weak sphincters, sacral nerve stimulation is a promising therapy. Other therapies, such as antegrade irrigation, may be helpful for patients with neurological disorders. CONCLUSION: Better imaging, refined classification and new operations are leading to improved surgical techniques for faecal incontinence.

Anus Diseases↗
PubMed2002

Predicting membrane oxygenator pressure drop using computational fluid dynamics.

Three-dimensional computational fluid dynamic (CFD) simulations of membrane oxygenators should allow prediction of spatially dependent variables and subsequent shape optimization. Fiber bed complexity and current computational limitations require the use of approximate models to predict fiber drag effects in complete device simulations. A membrane oxygenator was modified to allow pressure measurement along the fiber bundle in all cardinal axes. Experimental pressure drop information with water perfusion was used to calculate the permeability of the fiber bundle. A three-dimensional CFD model of a commercial membrane oxygenator was developed to predict pressure drops throughout the device. Darcy's Law was used to account for the viscous drag of the fibers and was incorporated as a momentum loss term in the conservation equations. Close agreement was shown between experimental and simulated pressure drops at lower flow rates, but the simulated pressure drops were lower than experimental results at higher flows. Alternate models of fiber drag effects and flow field visualization are suggested as means to potentially improve the accuracy of the flow simulation. Computational techniques coupled with experimental verification offer insight into model validity and show promise for the development of accurate three-dimensional simulations of membrane oxygenators.

Artificial Organs↗