5,201 research outputs found
Human Myeloma Marrow Cells in Immunologically Deficient Mice
Intact human bone marrow cells from 7 patients with myelomatosis were inoculated intravenously into adolescent CBA mice rendered immunologically deficient by thymectomy followed by total body irradiation (600 rad). Each inoculum of human myeloma marrow cells and subsequent passages of intact mouse marrow and spleen cells resulted in the presence of morphological changes in the marrow, spleen and peripheral blood of a proportion of these mice which were closely similar to those seen in the human donor. A substantial amount of human immunoglobulin (IgG and IgA) was detected in the sera of some of the mice showing morphological changes. Mice prepared identically but remaining uninoculated or receiving intact human bone marrow cells from 3 patients with no evidence of haematological malignancy showed none of these changes when examined after similar intervals
Modulation of type IV collagenase and plasminogen activator in a hamster fibrosarcoma by basement membrane components and lung fibroblasts.
The effect of basement membrane components (laminin, fibronectin and type IV collagen) and lung fibroblasts on type IV collagenase and plasminogen activator activity was investigated in a primary HSV-2-induced hamster fibrosarcoma, and its in vivo derived sublines and in vitro derived clones of varying metastatic potential. Fibronectin and type IV collagen were ineffective at influencing the expression of either type IV collagenase or plasminogen activator activity. Laminin, however, at concentrations of 1-10 micrograms ml-1 added to the serum-free culture supernatants, increased the release of type IV collagenase by up to 100% for the parental cell line. Three highly metastatic sublines (two from in vivo origin and one from in vitro cloning) showed increases of up to 300%. Non-metastatic sublines (two from in vivo origin and one from in vitro cloning), however, showed no increase in type IV collagenase activity. Plasminogen activator release from either the parental line cell or its metastatic sublines and clones, was unaffected by the addition of laminin. Addition of tumour cells to lung fibroblast monolayers resulted in an increased expression of PA activity in the supernatant, whilst type IV collagenase activity was reduced
Collapsars - Gamma-Ray Bursts and Explosions in "Failed Supernovae"
Using a two-dimensional hydrodynamics code (PROMETHEUS), we study the
continued evolution of rotating massive helium stars whose iron core collapse
does not produce a successful outgoing shock, but instead forms a black hole.
We study the formation of a disk, the associated flow patterns, and the
accretion rate for disk viscosity parameter, alpha ~ 0.001 and 0.1. For the
standard 14 solar mass model the average accretion rate for 15 s is 0.07 solar
masses per second and the total energy deposited along the rotational axes by
neutrino annihilation is (1 - 14) x 10**51 erg, depending upon the evolution of
the Kerr parameter and uncertain neutrino efficiencies. Simulated deposition of
this energy in the polar regions results in strong relativistic outflow - jets
beamed to about 1.5% of the sky. The jets remain highly focused, and are
capable of penetrating the star in 5 - 10 s. After the jet breaks through the
surface of the star, highly relativistic flow can commence. Because of the
sensitivity of the mass ejection and jets to accretion rate, angular momentum,
and disk viscosity, and the variation of observational consequences with
viewing angle, a large range of outcomes is possible ranging from bright GRBs
like GRB 971214 to faint GRB-supernovae like SN 1998bw. X-ray precursors are
also possible as the jet first breaks out of the star. While only a small
fraction of supernovae make GRBs, we predict that all GRBs longer than a few
seconds will make supernovae similar to SN 1998bw. However, hard, energetic
GRBs shorter than a few seconds will be difficult to make in this model.Comment: Latex, 66 pages including 27 figures (9 color), Submitted to The
Astrophysical Journal, latex uses aaspp4.sty. Figures also available at
http://www.ucolick.org/~andre
Social support for and through exercise and sport in a sample of men with serious mental illness.
Social support is important for people experiencing serious mental illness and is also important during the initiation and maintenance of exercise. In this article we draw on interpretive research into the experiences of 11 men with serious mental illness to explore four dimensions of social support both for and through exercise. Our findings suggest that informational, tangible, esteem, and emotional support were both provided for and given by participants through exercise. We conclude that experiences of both receiving and giving diverse forms of support in this way are significant for some people living with and recovering from serious mental illness
Astrophysical evidence for the existence of black holes
Following a short account of the history of the idea of black holes, we
present a review of the current status of the search for observational evidence
of their existence aimed at an audience of relativists rather than astronomers
or astrophysicists. We focus on two different regimes: that of stellar-mass
black holes and that of black holes with the masses of galactic nuclei.Comment: 23 pages, 3 figures, TeX forma
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