Xenotransplantation: Perspectives and limits

Xenotransplantation faces the dilemma of an unlimited supply of cells, tissues and organs on the one hand and severe obstacles and limits on the other. One reason for the limitations is that the source animal of choice, the pig, and the human recipient separated 90 million years ago during evolution, a time in which biological characteristics such as anatomy, physiology and immunology have had much time to drift far apart. The acceptance of such an evolutionary widely divergent organ, especially the heart of a pig, could evoke refusal of xenotransplantation in conservative and religious patients. New legal aspects of allocation of xenografts have therefore to be reflected upon and appropriate guidelines developed. Inquiries show, however, that the acceptance of all types of porcine organs would be high if the quality of life after receiving such a xenograft is comparable to that after receiving the same allograft. This individual benefit of a xenograft could lead to a disregard of the collective risk in terms of xenozoonoses, often presented as a catastrophic scenarium. Therefore, transplantation societies and ethics committees have published comments and even guidelines for handling future clinical xenotransplantation. All three monotheistic religions and Hinduism support the idea of saving and improving human life with the help of an animal organ. Copyrght (C) 2001 S. Karger AG, Basel

Impact of Ig-Therasorb (R) immunoapheresis on stability of xenogeneic ex vivo porcine liver perfusion - Value of aminotransferases and flow rates for the assessment of metabolic graft viability

Due to growing shortage of donor organs, the concept of extracorporeal pig liver perfusion in the treatment of acute liver failure has been rediscovered. Immunomodulation, such as immunoapheresis or inhibition of complement, results in long-term perfusion without exact knowledge of the remaining metabolic graft viability. This study was aimed at the comparison of conventional parameters of graft stability such as perfusion rates and release of aminotransferases with parameters of metabolic graft function. Ig-Therasorb(R) immunoapheresis (IA) of the xenogeneic perfusate was performed to protect the discordant pig livers from hyperacute rejection, mediated by preformed naturally occurring human xenogeneic antibodies. The application of IA created stable autologous graft reperfusion after a short time of xenoperfusion, but it was not able to prevent the livers from severe synthetic and functional damage. In the future, improvement of xenogeneic graft function, rather than pure prolongation of perfusion, must be the principal aim

Preface

This special issue of the Journal of Geophysical Research presents 47 papers developed from research on the two deep ice cores drilled in central Greenland during the years 1989-1993 by the U.S. Greenland Ice Sheet Project 2 (GISP2) and the European Greenland Ice Core Program (GRIP). In this grand experiment, two large ice-core-drilling programs were combined. A major reason was to validate the presence of fast climate oscillations that could not be verified by a single deep ice core

Neural Mechanisms of Anaphoric Reference Revealed by fMRI

Pronouns are bound to their antecedents by matching syntactic and semantic information. The aim of this functional magnetic resonance imaging study was to localize syntactic and semantic information retrieval and integration during pronoun resolution. Especially we investigated their possible interaction with verbal working memory manipulated by distance between antecedent and pronoun. We disentangled biological and syntactic gender information using German sentences about persons (biological/syntactic gender) or things (syntactic gender) followed by congruent or incongruent pronouns. Increasing the distance between pronoun and antecedent resulted in a short and a long distance condition. Analysis revealed a language related network including inferior frontal regions bilaterally (integration), left anterior and posterior temporal regions (lexico-semantics and syntactic retrieval) and the anterior cingulate gyrus (conflict resolution) involved in pronoun resolution. Activities within the inferior frontal region were driven by Congruency (incongruent > congruent) and Distance (long > short). Temporal regions were sensitive to Distance and Congruency (but solely within long distant conditions). Furthermore, anterior temporal regions were sensitive to the antecedent type with an increased activity for person pronouns compared to thing pronouns. We suggest that activity modulations within these areas reflect the integration process of an appropriate antecedent which depends on the type of information that has to be retrieved (lexico-syntactic posterior temporal, lexico-semantics anterior temporal). It also depends on the overall syntactic and semantic complexity of long distant sentences. The results are interpreted in the context of the memory–unification-control model for sentence comprehension as proposed by Vosse and Kempen (2000), Hagoort (2005), and Snijders et al. (2009)

Non-specific Health complaints and self-rated health in pre-adolescents:impact on primary health care use

Abstract The objective of the present study was to explore past and future primary health care use in preadolescents reporting frequent non-specific health complaints or a low self-rated health compared to that of preadolescents with no frequent health complaints or with good self-rated health. The study was conducted as a cohort study based within the Danish National Birth Cohort (1996–2002). Information on non-specific health complaints and self-rated health was obtained by an 11-year follow-up questionnaire. Information about number of general practitioner (GP) contacts was obtained from the Health Insurance Service Register. A total of 44,877 pre-adolescents gave complete exposure information. Pre-adolescents who reported frequent non-specific health complaints had a higher use of GP compared to pre-adolescents without complaints across the five years following the index date (somatic complaints: IRR = (1.46 [1.38; 1.55], mental complaints: IRR = 1.16 [1.12; 1.19], both complaints: IRR = 1.58 [1.47; 1.69]). The same pattern was found for the association between low self-rated health and number of GP contacts (IRR = 1.41 (1.36; 1.46)). Non-specific health complaints and a poor self-rated health in pre-adolescents was associated with a higher past and future use of GP, indicating a need for development of early interventions with help for symptom management

Long-term changes in the acid and salt concentrations of the Greenland Ice Core Project ice core from electrical stratigraphy

Continuous electrical records covering a climatic cycle are presented for the Greenland Ice Core Project deep ice core from Greenland. Electrical conductivity measurement (ECM) measures the acid content of the ice, and the dielectric profile (DEP) responds to acid, ammonium, and chloride. All features seen can be explained by chemical changes in the ice, and there is no evidence so far for any major change in electrical response with depth or age of the ice. Both records are dominated by the acidity of the ice which varies strongly from acidic in warm periods to alkaline in cold periods, controlled by neutralization by alkaline dust (calcareous and other mineral dust). When Ca is low, the acidity (mainly nitric acid) has a fairly constant background level throughout the cycle, with slightly lower values in ice believed to be from the last interglacial. Ca has to rise only slightly to neutralize the available acidity, so that acidity is a highly nonlinear reflection of climate changes. If neutralization occurred in the aerosol (rather than in the ice), then the number of cloud condensation nuclei over parts of the northern hemisphere could have been reduced, leading to reduced cloud albedo. This nonlinear feedback may have some importance for modeling of climate change. When both acid and ammonium levels are low, the DEP signal can be used to give a rapid indication of chloride trends

Oxygen isotope composition of surface snow collected along the traverse route from Zhongshan Station toward Dome A, Antarctica

Oxygen isotope composition of surface snow sampled in the austral summer of 1998/1999 along the traverse route from Zhongshan Station toward Dome A, Antarctica is measured with the conventional mass spectrometer technique. The results of measurement show that oxygen isotope composition of surface snow varies in a wide range from -22.51‰ to -50.67‰, and has a tendency that isotopic values gradually decrease with increase of distance from Zhongshan Station and altitude. Linear regression analysis indicates that there exists good correlation between oxygen isotope composition of surface snow and distance from Zhongshan Station, altitude and/or latitude, which actually reflects the close relation between stable isotope composition and air temperature