Une méthode de culture in vivo des précurseurs hématopoiétiques: la technique des chambres de diffusion.

Several studies have demonstrated that hematopoietic cells can be successfully cultured for several weeks in diffusion chambers (DC) implanted both in experimental animals and man. This technique is a useful assay of hematopoietic cell growth and a powerful tool for studying stem cell kinetics in vivo. The evaluation of the effects of humoral factors on hematopoietic cell proliferation and differentiation in this system has led to identification of both stimulators and inhibitors that may be different from the well characterized cytokines.SCOPUS: re.jinfo:eu-repo/semantics/publishe

In vivo inhibition of granulopoiesis in acute inflammation requires T lymphocyte integrity

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

In vivo elaboration of CSF in acute inflammation: Proportionality to the intensity of the inflammatory stimulus and requirement of T lymphocytes

The colony-stimulating factor(s) (CSF) that stimulates the in vitro growth of bone marrow granulocyte-monocyte progenitors (CFU-GM) increases in the serum of mice challenged by an aseptic abscess induced by copper rod insertion. The effect of the inflammation on the increase of serum CSF is dose-related. The creation of 3 aseptic abscesses indeed results in a higher and longer elevation of serum CSF than 1 abscess. Serum CSF also increases in parallel with the rise in bone marrow CFU-GM; this is consistent with the CSF playing a role in regulation of haematopoiesis in vivo. From previous studies, it appears that T lymphocytes play a central role in the regulation of haematopoiesis. In order to determine the role of T lymphocytes in the inflammation response, cyclosporin A (CyA), an inhibitor of T lymphocyte function, was given in vivo, 2 days before inflammation induction. CyA abrogates the increase in both serum CSF and CFU-GM. Furthermore, a lower increase in serum CSF was observed in copper-implanted nude mice. These results suggest that the CSF production induced by inflammation requires the functional integrity of T lymphocytes.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Exploring factors influencing acceptance use of Oman virtual science library (Masader) in Sultanate of Oman

This study investigated factors that influence faculty members attitudes toward accepting Masader e-resources at the higher education in Sultanate of Oman, this is due to the unexpected decrease after the first year of use by the academics. To achieve this, a set of behavioral factors has been relied upon, such as the behavioral intention (BI) and the perceived usefulness (PU) and perception of easiness (POE). These factors may also be affected and related to other external factors such as system quality. The relationships between these different factors are also formulated as hypotheses to verify their stability and validity. The study population consists of this study will only focus on academics in universities and colleges in the Sultanate of Oman. The researcher used mixed methods for the current investigation, where both qualitative and quantitative approaches are joined for a blend of data. The study found a direct relationship between (POE& PU) and the (BI) to use, and direct relationship between (SQ) and (POE& PU), which in turn affects (BI) to use

Faculty acceptance of e-resources at applied sciences colleges in Oman: application of the Technology Acceptance Model (TAM)

This study investigated factors that influence faculty members attitudes toward accept e-resources at the Applied Sciences colleges in Sultanate of Oman, this is due to the unexpected decrease after the first year of use by the faculty. To achieve this, a set of behavioral factors has been relied upon, such as the behavioral intention (BI) and the perceived usefulness (PU) and perception of easiness (POE). These factors may also be affected and related to other external factors such as information quality. The study population consists of faculty members working in six CASin the Sultanate of Oman. 120 of them were chosen as a representative sample, and a questionnaire was distributed to them, which included various factors to measure their acceptance of the e-resources available on the electronic system. The results of the study confirmed the presence of a statistically significant relationship in the effect of behavioral factors such as (PU) and (POE) in using e-resources. It also indicated that there is a direct relationship between information quality (IQ) as an external variables and belief variables (PU and POE) which in turn affects the behavioral intention to use e-resources (BI)

Acute inflammation effects on in vivo granulopoiesis: Comparative studies in health and leukaemic mice

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Natural killer (NK) cells inhibit human umbilical cord blood erythropoiesis.

To examine the role of NK cells on in vitro human umbilical cord (HUC) blood erythropoietic progenitor growth, 25 normal HUC blood samples were depleted of CD56+ cells by using immunomagnetic beads coated with CD56 monoclonal antibodies (mAb). When stimulated by erythropoietin (Epo) to form colonies in plasma clot medium, the CD(56+)-depleted preparations demonstrated a two-fold increase in the number of early erythropoietic progenitors (BFU-E) over nondepleted preparations. This stimulatory effect of CD56+ depletion on BFU-E growth was not due to artifactual stimulations of other accessory cells by the mAb or the dynabeads used in the depletion procedure, since separate addition of these materials to culture did not exert any stimulatory effect on BFU-E growth. Direct co-culture of purified NK and autologous cord blood mononuclear cells (MNC) in plasma clot medium resulted in a dose-dependent decrease in BFU-E population. In addition, when NK and MNC were cocultured separately in double-layer cultures, the expansion of BFU-E was significantly decreased. Because direct cell-to-cell contact is prohibited in double-layer cultures, the observed inhibition of BFU-E proliferation could be mediated at least in part through soluble factors. To test this hypothesis, NK cell supernatant fluid obtained 24 hours after NK cell incubation was added to plasma clot culture medium. A significant decrease in BFU-E number was again observed. In conclusion, our results indicate that HUC blood BFU-E proliferation is inhibited by NK cells, and that the mechanism of this inhibition is mediated, at least in part, by one or more humoral factors.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe