Biomedical subjects

S Corbel

Publications and source records attributed to S Corbel.

7 recordsLinked to original sources

PubMed2002

Large-scale, decelerating, relativistic x-ray jets from the microquasar XTE J1550-564.

We have detected, at x-ray and radio wavelengths, large-scale moving jets from the microquasar XTE J1550-564. Plasma ejected from near the black hole traveled at relativistic velocities for at least 4 years. We present direct evidence for gradual deceleration in a relativistic jet. The broadband spectrum of the jets is consistent with synchrotron emission from high-energy (up to 10 tera-electron volts) particles that were accelerated in the shock waves formed within the relativistic ejecta or by the interaction of the jets with the interstellar medium. XTE J1550-564 offers a rare opportunity to study the dynamical evolution of relativistic jets on time scales inaccessible for active galactic nuclei jets, with implications for our understanding of relativistic jets from Galactic x-ray binaries and active galactic nuclei.

Journal Article↗

PubMed1999

The Distance to the Soft Gamma Repeater SGR 1627-41.

We report millimeter observations of the line of sight to the recently discovered soft gamma repeater SGR 1627-41, which has been tentatively associated with the supernova remnant (SNR) G337.0-0.1. Among the eight molecular clouds along the line of sight to SGR 1627-41, we show that SNR G337.0-0.1 is probably interacting with one of the most massive giant molecular clouds (GMCs) in the Galaxy, at a distance of 11 kpc from the Sun. Based on the high extinction to the persistent X-ray counterpart of SGR 1627-41, we present evidence for an association of this new soft gamma repeater (SGR) with the SNR G337.0-0.1; they both appear to be located on the near side of the GMC. This is the second SGR located near an extraordinarily massive GMC. We suggest that SGR 1627-41 is a neutron star with a high transverse velocity ( approximately 1000 km s-1) escaping the young ( approximately 5000 yr) SNR G337.0-0.1.

Journal Article↗

PubMed1999

[Rapid prototyping and bone reconstruction].

The authors describe the main techniques for rapid prototyping used in the medical field, with particular emphasis on Laser stereolithography. They describe the basics of the technique as well as the procedures they currently use to construct anatomic specimens from scanned images. For more than 10 years, the targets of researchers in the field of bone reconstruction in craniofacial surgery have been: to design a system to acquire data directly from CT-scans, to optimize modelling, processing and materials, to verify the possibility of producing prefabricated prostheses with data from preoperative models (22 cases). The target of integrating this technique into therapeutic protocols has been reached. The current trend in research is to produce prostheses from biocompatible materials directly from CT scan data by Laser stereolithography.

Computer-Aided Design↗

PubMed1997

Binding of histamine H3-receptor antagonists to hematopoietic progenitor cells. Evidence for a histamine transporter unrelated to histamine H3 receptors.

Hematopoietic progenitor cells can take up histamine or release IL-3-induced histamine through a bi-directional transport system that is blocked by H3-receptor antagonists. In the present study we demonstrate a correlation between the affinity of various H3-receptor antagonists and their potency as inhibitors of histamine uptake. All compounds that blocked histamine uptake also inhibited IL-3-induced histamine release. Yet, classical H3 receptors are not involved in this biological activity, since highly specific histamine H3-receptor agonists neither alter histamine uptake nor affect the release of endogenous histamine synthesized in response to IL-3. Furthermore, the inhibitory effect of H3-receptor antagonists on histamine uptake was not reversed by the agonists. Unlike H3-receptor antagonists, the agonists did not displace the binding of the labeled antagonist iodoproxyfan.

Animals↗

PubMed1996

Evidence for bidirectional histamine transport by murine hematopoietic progenitor cells.

Murine hematopoietic progenitor cells synthesize substantial amounts of histamine in response to IL-3 or calcium ionophore. They also take up extracellular histamine by an active transport system. In the present study we demonstrate that this system mediates both influx and efflux of histamine. Indeed, MR16155 and thioperamide, the two H3 antagonists which are most effective in inhibiting histamine uptake, likewise diminish the release of preloaded histamine from bone marrow cells. These compounds also inhibit the release of histamine which has been newly synthesized by hematopoietic progenitors in response to IL-3 or calcium ionophore, as assessed by the accumulation of the mediator inside the cells in the presence of the antagonists. The potency of different histamine receptor antagonists as inhibitors of histamine release increases with their capacity to block histamine uptake.

Animals↗

PubMed1995

Murine hematopoietic progenitors are capable of both histamine synthesis and uptake.

We examined various murine hematopoietic cell populations for their capacity to interact with radiolabeled histamine. Only bone marrow cells (BMC) retained substantial amounts of radioactivity, in contrast to thymus, spleen, and peritoneal cells. The characteristics of this interaction are consistent with histamine uptake rather than receptor binding. Indeed, this process is temperature and sodium dependent and reduced by various metabolic inhibitors. Furthermore, the effect of antagonists or agonists of the H1, H2, and H3 receptor subtypes is not in accordance with the involvement of either of these receptors in histamine binding. The target cells of histamine copurify with hematopoietic progenitors in the low-density BM population. They are most enriched in the subset sorted from the blast cell window on the basis of high rhodamine retention. This fraction contains on the average 80% to 90% immature cells and is highly enriched for several clonogenic progenitor subsets. Sixty percent of the Rh-bright cells are labeled by 3H-histamine, as assessed by autoradiography, suggesting that a variety of immature cells participates in this phenomenon. Furthermore, in all sorting procedures used here, the cells capable of histamine uptake coenrich with those producing histamine in response to interleukin-3, indicating at least a partial identity between these cells.

Animals↗

PubMed1994

Evidence for histamine uptake by murine hematopoietic progenitors.

Based on previous evidence for a role of exogenous and endogenous histamine, we have examined whether this amine can effectively interact with hematopoietic progenitors. We show that tritiated histamine is retained preferentially by bone marrow cells as compared with peritoneal, thymic or spleen cells. Cells interacting with histamine copurify with progenitors in the low density bone marrow fraction. Among this cell population, 5% are labeled as assessed by autoradiography. The characteristics of histamine retention by these cells are consistent with active uptake rather than binding to a known receptor since (a) it is almost completely abrogated at 4 degrees C, by sodium azide or chloroquine, (b) histamine is internalized, and (c) relatively high concentrations of classical receptor antagonists are required to inhibit histamine retention by bone marrow cells.

Animals↗