B J Ashmead

University of Victoria, Victoria, British Columbia, Canada

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Publications (5)139.96 Total impact

  • The Lancet 11/1993; 342(8875):872-3. DOI:10.1016/0140-6736(93)92734-B · 45.22 Impact Factor
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    ABSTRACT: In human breast carcinomas tumor cells and macrophages are often proximal. We previously reported on the relationship between tumor cell growth and macrophage concentration and report here on the possible involvement of macrophages in the metastatic process. We hypothesize that during the initial stages of metastasis, tumor cells are likely to encounter macrophages and form aggregates. Using a cell culture method that encourages cellular interactions, we found aggregates involving macrophages. Macrophages partly or completely surround other cell types without any apparent ill effect. Units involving macrophages and tumor cells would possess many properties necessary for invasion, which is a normal process for macrophages. Properties such as motility and production of specific enzymes necessary to traverse the extracellular matrix, basement membrane, and endothelial cell barriers may provide an advantage for tumor cells. Physical support and protection from immune recognition during transport of the tumor cell through the vascular system may also be enhanced, and paracrine growth stimulation and angiogenic activity may be provided at the new metastatic site. Verification of these observations in vivo could lead to new directions for limiting breast cancer metastasis.
    Journal of Leukocyte Biology 11/1993; 54(4):360-2. · 4.30 Impact Factor
  • JP van Netten · IG Thornton · C Fletcher · BJ Ashmead
    The Lancet 01/1993; 342(s 8886–8887):1561–1562. DOI:10.1016/S0140-6736(05)80142-4 · 45.22 Impact Factor
  • J P van Netten · I G Thornton · C Fletcher · B J Ashmead
    The Lancet 01/1993; 342(8886-8887):1561-2. DOI:10.1016/S0140-6736(05)80140-0 · 45.22 Impact Factor
  • D. A. Lovejoy · B. J. Ashmead · I. R. Coe · N. M. Sherwood
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    ABSTRACT: Gonadotropin-releasing hormone (GnRH) immunoreactivity was studied in two species of elasmobranchs, spiny dogfish (Squalus acanthias) and black skate (Bathyraja kincaidii). Immunoreactive material in brain sections was identified using the avidin-biotin technique with the horseradish peroxidase reaction. Although there were a few GnRH immunoreactive cells, GnRH fibers were greatest in the telencephalon of both species and were associated primarily with the terminal nerve system. In the dogfish, many immunoreactive fibers extended towards the ventromedial surface of the caudal forebrain. This site may be the locus for neurosecretion. GnRH fibers were found in the preoptico-hypophyseal tract of dogfish, but not in the media eminence or pituitary. Immunoreactive material was less abundant in other regions of the brain, although a diffuse fiber network throughout the brain including the brain stem was observed. © 1992 Wiley-Liss, Inc.
    Journal of Experimental Zoology 09/1992; 263(3):272 - 283. DOI:10.1002/jez.1402630307