Biomedical subjects
Publications and source records attributed to U Dahmen.
A two-stage jet polishing technique is described which, utilising the effects of the characteristic current-voltage behaviour of electropolishing solutions, can produce excellent TEM foils of relatively coarse two-phase materials.
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Spontaneous orthotopic liver allograft acceptance associated with microchimerism in mice induces tolerance to subsequent skin or heart transplants from the donor but not third-party animals. Despite in vivo hyporesponsiveness, in vitro MLC and CTL assays showed continuing antidonor reactivity. Cells isolated from recipients' spleens and grafted livers, when tested in MLC and CTL assays, were antidonor reactive out to 3 months to the same degree as splenocytes obtained from either naive or presensitized (with skin or heart) mice. Nevertheless, passive transfer of splenocytes or liver lymphocytes from liver tolerant mice, but not naive or sensitized donor strain mice, were able to prolong skin graft survival significantly in naive irradiated recipients. By using a strain combination in which the donor but not the recipient expressed the stimulatory endogenous super-Ag (Mlsf), it was possible to determine whether super-Ag-reactive T cells bearing V beta 5 and V beta 11 were deleted or anergic. Phenotypic analysis of cells isolated from recipients' spleens and grafted livers (up to 90 days after transplant), when compared with naive animals, showed no significant difference in V beta 5 and V beta 11 TCR expression. Additionally, when these isolated spleen cells were tested for antibody-mediated stimulation, both anti-V beta 5 and V beta 11 TCR mAb led to marked proliferation of cells obtained from naive and liver-transplanted recipients, but as expected, proliferation was very low in cells from naive donors. These results suggest that liver transplantation induces donor-specific tolerance in vivo, which may not be reflected in in vitro proliferative and cytotoxicity assays (split tolerance). Furthermore, this tolerance does not seem to be induced by clonal deletion or anergy of minor-lymphocyte-stimulating-antigen-reactive T cells in the recipients.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
After a 5 years' experience of cerebral sonography (about 4,500 recordings) in infants we are trying to establish correlations between alterations of anatomical structures and the further clinical development. Obviously there is no constant connexion between a simple subependymal haemorrhage and the further neurological symptoms. At the age of two and more years, about 30% had a normal state, the other part had very different clinical signs. Even an uncomplicated ventricular haemorrhage had no definite influence on the child's development in most cases. Ischemic infarctions seem to have a better prognosis than borderline-infarctions. Real intracranial cysts and slight brain atrophy seem to have only distinct neurological symptoms. Porencephalic defects or brain necrosis, e.g. after parenchymatous haemorrhages and infarctions as well as generalized hypoxic encephalopathies with increased echogenicy and progressive brain atrophy nearly always showed neurological defects, though the dimension of the brain's alteration does not clearly correlate to the clinical symptoms and the child's development. It is not possible to make a prognostic evaluation by cerebral sonography in hypoxic-ischemic brain-lesions within the first 3 weeks post partum. A more exact judgement will be given after further regular sonographic observations in all high-risk infants within the first year. Beyond this, technical and organisation-improvements will probably allow a more exact statement in future.
Rats receiving either kidney or liver grafts were vaccinated with recombinant hepatitis B virus (HBV) vaccine either 1 or 10 weeks post-transplantation to explore the nonspecific immunosuppressive effect of transplantation surgery on antibody development. Response rate and geometric mean titer of the anti-HBs antibody were significantly lower in organ-transplanted animals undergoing early vaccination compared to unoperated control animals. Both parameters were affected when vaccination was performed early after kidney transplantation, but also in case of late vaccination in liver graft recipients. The nonspecific suppressive effect of transplantation surgery on the humoral immune response was related to the time point of vaccination after surgery and the extent of the surgical intervention and lasted longer than previously reported.