Necrolytic migratory erythema with myelodysplastic syndrome without glucagonoma

Necrolytic migratory erythema is a cutaneous paraneoplastic manifestation, which is usually associated with a glucagon-secreting pancreatic tumor. However, it also may occur in other circumstances in which serum glucagon is elevated, as in hepatic cirrhosis. Rarely, necrolytic migratory erythema is reported in association with a jejunal and rectal adenocarcinoma or villous atrophy of the small intestine without any evidence for increased serum glucagon levels. In this context we report the case of an 85-year-old male with myelodysplastic syndrome who developed typical necrolytic migratory erythema without glucagonoma syndrome or evidence for other pancreatic or liver disease. We suggest that, in addition to the diseases listed, myelodysplastic syndrome might be able to cause necrolytic migratory erythema.

Distinct effects of sphingosine-1-phosphate, lysophosphatidic acid and histamine in human and mouse dendritic cells

Dendritic cells (DC) are specialized antigen presenting cells characterized by their ability to migrate into target sites and secondary lymphoid organs in order to process antigens and activate naive T cells. Previously, we have shown that several secretion products from platelets and mast cells such as histamine, sphingosine-1-phosphate (S1P), and lysophosphatidic acid (LPA) have chemotactic activity towards immature human DC. Furthermore, they limit the capacity of mature human DC to initiate and amplify T helper cell type 1 (Th1) immune responses by inhibition of interleukin (IL)-12 and upregulation of IL-10 secretion. In this study we focused on the effect of these agents on murine DC. In murine DC no influence on IL-10 and IL-12 release by these agents was observed. Moreover, histamine and LPA failed to stimulate chemotaxis and actin reorganization in mouse DC. Instead, S1P had chemotactic activity and induced actin polymerization in immature as well as mature mouse DC. Therefore, our in vitro data implicate that in contrast to humans the function and immunological capacity of murine DC are not so tightly controlled by mast cell and platelet-derived secretion products such as histamine, S1P and LPA. These findings suggest that mouse models might underestimate the complex regulative network between mast cells, platelets and DC.

The role of CD44 during CD40 ligand-induced dendritic cell clustering and maturation

The interaction between CD40 on dendritic cells (DC) and its ligand CD154 has been recognized to be an important feature in the maturation of DC. Here, we were interested in the role of CD44 a surface receptor shown to mediate cell-cell adhesion and binding to Hyaluronic acid (HA). Western blot analysis of human DC stimulated for 3-12 h with CD154 revealed the rapid induction of the 85 kDa standard form of CD44 and an increased HA-binding affinity. Time-lapse video-imaging microscopy of human DC co-cultured on CD154-transfected murine fibroblasts showed that the CD44 up-regulation coincided with the rapid induction of homotypic DC clustering, which did not occur on empty vector-transfected fibroblasts. In this system, addition of anti-CD44s mAbs abrogated DC-cluster formation, thereby inhibiting further maturation, as shown by a reduced TNF-alpha production and inhibition of CD154-induced MHC class II up-regulation. However, co-incubation with HA-degrading enzymes induced no changes in the CD154-mediated DC clustering and maturation.

Learning from Worked-Out Examples: The Effects of Example Variability and Elicited Self-Explanations

It was investigated to what extent example variability and the elicitation of sophisticated self-explanations foster the acquisition of transferable knowledge by learning from worked-out examples. In addition, it was asked whether the effects of these factors are moderated by the learners' levels of prior topic knowledge. To this end, we had 56 apprentices from a bank learn calculation of compound interest and real interest. They were randomly assigned to the four conditions of a 2 x 2-factorial design (factor 1: uniform vs. multiple examples; factor 2: spontaneous vs. elicited self-explanations). The learning results were measured by a post-test comprising near-transfer problems and far-transfer problems. It was found that the acquisition of transferable knowledge can be supported by eliciting self-explanations. In the case of near transfer, especially learners with low levels of prior topic knowledge profited from the elicitation procedure. On the whole, the findings underline the "causal" relevance of the quality of self-explanations for knowledge acquisition by learning from worked-out examples. The assumption that multiple examples foster transfer performance, at least when sophisticated self-explanations are elicited, was not supported. Copyright 1998 Academic Press.