Transplantation

About: Transplantation is a research topic. Over the lifetime, 276584 publications have been published within this topic receiving 7961661 citations.

Application of reduced-size liver transplants as split grafts, auxiliary orthotopic grafts, and living related segmental transplants.

Abstract: The University of Chicago program in pediatric liver transplantation continues actively to seek innovative surgical solutions to problems related to the management of children with end-stage liver disease. Among the most important problems facing these children is a shortage of donor organs, which results from three factors in addition to the actual supply of pediatric donors: the concentration of pediatric liver disease in the population younger than 2 years; the necessity for a graft that is small enough; and the epidemiology of accidents and other events that lead to organ donation. Transplantation using a liver lobe as a graft overcomes size disparity and shifts the available supply of organs from older donors to younger recipients. This work describes the technical aspects of recent innovations in the use of liver lobes in pediatric transplantation, simple reduced-size liver transplantation (RLT), split-liver transplantation (SLT), orthotopic auxiliary liver grafting (ALT), and transplantation using a living related donor (LRLT), and compares their results. Since November 1986 a total of 61 procedures have been performed in which a liver lobe was used as a graft: 26 RLT; 30 SLT, 25 in children and 5 in adults; 5 LRLT; and 1 ALT. Overall 62% of transplants performed in children have involved using a liver lobe as a graft. The rates of complications are somewhat higher than with whole-liver transplantation, but this may not be entirely the result of the complex procedures. Split liver transplantation is associated with the highest mortality and complication rates. Living related liver transplantation has been associated with complications in donors and recipients, but to date survival is 100%. Orthotopic auxiliary liver transplantation effectively corrected the metabolic defect in one patient with ornithine transcarbamylase deficiency. Overall the various modalities of using graft reduction have resulted in postoperative results similar to those achieved with full-size grafts, while pretransplantation mortality has been limited to less than 2%. Thus the use of grafts as liver lobes accomplishes the goal of reducing global mortality among children with end-stage liver disease, but at the cost of increased surgical complexity and more postoperative complications.

Testing the Adaptive Plasticity Hypothesis: Density-Dependent Selection on Manipulated Stem Length in Impatiens capensis

Abstract: In plants, stem elongation at high density in response to vegetation shade is hypothesized to be an example of adaptive phenotypic plasticity. Elongated stems may increase the light capture for plants in dense stands, while nonelongated stems may be favored for plants in low density. We tested the adaptive value of plastic stem elongation in Impatiens capensis by manipulating the controlling light cue, red to far red ratio, to produce elongated and nonelongated plants. These plants were then transplanted into high and low densities in a natural population. The results supported the adaptive plasticity hypothesis; elongated plants were more fit at high density, and suppressed plants were more fit at low density. Phenotypic selection analysis revealed selection for increased height in high density and for decreased height relative to leaf length in low density. Elongated plants showed less growth of the second internode at 2 wk after transplantation in both densities, which suggests a cost of elongation. Di...