John M. Pawelek

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BACKGROUND Tumor cell fusion with motile bone marrow-derived cells (BMDCs) has long been posited as a mechanism for cancer metastasis. While there is much support for this from cell culture and animal studies, it has yet to be confirmed in human cancer, as tumor and marrow-derived cells from the same patient cannot be easily distinguished genetically. (More)
We describe a new phenotype of wide occurrence in human cancer: expression of coarse vesicles rich in beta1,6-branched oligosaccharides. beta1,6-branching, catalyzed by GNT-V, is associated with metastasis and predicts poor survival in primary human breast and colon carcinomas. Yet little is known on the histopathology of this phenomenon. We studied(More)
Modern techniques offer an opportunity for a more complete evaluation of melanin production in the uvea and retinal pigment epithelium (RPE). By measuring the release of tritium from tritiated tyrosine in homogenized samples of adult bovine RPE as well as iris and choroid, tyrosinase activity could be demonstrated in both the uveal tract and the RPE.(More)
This perspective article highlights the leukocyte-cancer cell hybrid theory as a mechanism for cancer metastasis. Beginning from the first proposal of the theory more than a century ago and continuing today with the first proof for this theory in a human cancer, the hybrid theory offers a unifying explanation for metastasis. In this scenario, leukocyte(More)
The major regulators of melanogenesis are glycoproteins, however no role for glycosylation in the pathway has yet been described. We stained skin biopsies and melanocyte-keratinocyte co-cultures with a panel of 20 lectins as oligosaccharide markers. Notably, the Elderberry Bark Lectin (EBL/SNA) stained melanocytes in both systems. EBL binds the sequence(More)
The pigments eumelanin and pheomelanin are the visually most striking products of specialized neural crest-derived cells (melanocytes), and provide color to both epidermis and hair shafts. While the intriguing and controversial biological functions of these multifaceted heteropolymers will be discussed in a later feature, here it is explored how their(More)
BACKGROUND Metastatic disease is the principal cause of mortality in cancer, yet the underlying mechanisms are not fully understood. Macrophage-cancer cell fusion as a cause of metastasis was proposed more than a century ago by German pathologist Prof. Otto Aichel. Since then this theory has been confirmed in numerous animal studies and recently in a(More)
A review of the studies done at Yale on the role of MSH in regulating pigmentation and growth of Cloudman (S91) melanoma cells is presented. The areas covered include the isolation and analyses of mutant cell lines unresponsive to MSH; the role of cyclic AMP, cyclic AMP-dependent protein kinases, and protein phosphorylation reactions in the response of MSH;(More)
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