Significantly decreased platelet serotonin contents were measured in rheumatoid arthritis, systemic lupus erythematosus (SLE), progressive systemic sclerosis, and mixed connective tissue disease. An inverse relationship between platelet serotonin levels and clinical disease activity was observed in both rheumatoid arthritis and systemic lupus erythematosus. SLE patients with multiple organ involvement showed the lowest platelet serotonin values. No correlation was observed between platelet serotonin contents and nonsteroidal antiinflammatory drug treatment, presence of circulating platelet reactive IgG, or the amount of circulating immune complexes. The results are interpreted as indicating platelet release occurring in vivo during inflammatory episodes of the rheumatic disorders investigated.In addition to their role in blood coagulation, platelets have been shown to play an important part as intravascular inflammatory cells (1). Substances such as thrombin, collagen, ADP, prostaglandin endoperox- Supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 5 4 4 3 .

In this study, we analyzed whether retroviral integration sites in repopulating hematopoietic cells correlate with genes expressed in fractions enriched in hematopoietic stem cells (HSCs). We have previously described microarray studies of two populations enriched in HSCs: CD34 + /CD38 − and the slow dividing fraction of CD34 + /CD38 − cells (SDF). Furthermore, we demonstrated that oncoretroviral integrations in severe combined immunodeficient repopulating cells are preferentially located near the transcription start. Here, we have identified 117 corresponding cDNA clones on our microarray representing genes with retroviral integration sites. These genes revealed a higher mean signal intensity in comparison with either all genes on the array or a subset of control genes with retroviral integrations in HeLa cells. Furthermore, these genes demonstrated a higher expression in CD34 + / CD38 − cells and SDF. The association of gene expression and retrovirally targeted genes observed here will help to elucidate the molecular characteristics of primitive repopulating hematopoietic cells.

Local drug-disposition kinetics after interstitial application can be monitored noninvasively by in vivo [19F]-NMR spectroscopy. Disposition kinetics after local injection is highly variable and has a slow component in this tumor, whereas it is much less variable and relatively fast in subcutaneous tissue. The results suggest that NMR spectroscopy may be useful for in vivo studies of drug release from depot preparations designed for interstitial application.