History of clinical transplantation

How transplantation came to be a clinical discipline can be pieced together by perusing two volumes of reminiscences collected by Paul I. Terasaki in 1991-1992 from many of the persons who were directly involved. One volume was devoted to the discovery of the major histocompatibility complex (MHC), with particular reference to the human leukocyte antigens (HLAs) that are widely used today for tissue matching.1 The other focused on milestones in the development of clinical transplantation.2 All the contributions described in both volumes can be traced back in one way or other to the demonstration in the mid-1940s by Peter Brian Medawar that the rejection of allografts is an immunological phenomenon.3,4 © 2008 Springer New York

History of clinical transplantation

The emergence of transplantation has seen the development of increasingly potent immunosuppressive agents, progressively better methods of tissue and organ preservation, refinements in histocompatibility matching, and numerous innovations is surgical techniques. Such efforts in combination ultimately made it possible to successfully engraft all of the organs and bone marrow cells in humans. At a more fundamental level, however, the transplantation enterprise hinged on two seminal turning points. The first was the recognition by Billingham, Brent, and Medawar in 1953 that it was possible to induce chimerism-associated neonatal tolerance deliberately. This discovery escalated over the next 15 years to the first successful bone marrow transplantations in humans in 1968. The second turning point was the demonstration during the early 1960s that canine and human organ allografts could self-induce tolerance with the aid of immunosuppression. By the end of 1962, however, it had been incorrectly concluded that turning points one and two involved different immune mechanisms. The error was not corrected until well into the 1990s. In this historical account, the vast literature that sprang up during the intervening 30 years has been summarized. Although admirably documenting empiric progress in clinical transplantation, its failure to explain organ allograft acceptance predestined organ recipients to lifetime immunosuppression and precluded fundamental changes in the treatment policies. After it was discovered in 1992 that long-surviving organ transplant recipient had persistent microchimerism, it was possible to see the mechanistic commonality of organ and bone marrow transplantation. A clarifying central principle of immunology could then be synthesized with which to guide efforts to induce tolerance systematically to human tissues and perhaps ultimately to xenografts

The role of the epikarst in karst and cave hydrogeology: a review

The epikarst (also known as the subcutaneous zone) comprises highly weathered carbonate bedrock immediately beneath the surface or beneath the soil (when present) or exposed at the surface. Porosity and permeability are higher near the surface than at depth, consequently after recharge percolating rainwater is detained near the base of the epikarst, the detention ponding producing an epikarstic aquifer. Such an aquifer is found only where the uppermost part of the vadose zone is very weathered compared to the bedrock at depth. Sometimes this contrast in porosity and permeability does not occur either because the epikarst has been scraped off by glacial scour or because high porosity exists throughout the bedrock. In some conditions porosity may even diminish near the surface because of case-hardening. The epikarst is best developed in pure, crystalline limestones or marble where it is typically about 10 m thick. It then contains a suspended aquifer that is under-drained and sustains the distal tributaries of cave streams and small perennial flows emerging on hillsides (epikarstic springs). Slow leakage paths from the epikarst maintain seepage to many stalactites throughout the year. A distinction should be recognized between the location (and form) of the epikarst and the function of the epikarst, because the near surface zone in carbonate rocks does not always contain a suspended aquifer

Ein neues Doppelkristallspektrometer fuer Praezisionskernspektroskopie Abschlussbericht

Available from TIB Hannover: DtF QN1(35,45) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman