Applied Science Private University

About: Applied Science Private University is a education organization based out in Amman, Jordan. It is known for research contribution in the topics: Population & Catalysis. The organization has 4124 authors who have published 5299 publications receiving 116167 citations.

Intrinsic antibody-dependent enhancement of microbial infection in macrophages: disease regulation by immune complexes.

Abstract: Summary A wide range of microorganisms can replicate in macrophages, and cell entry of these pathogens via non-neutralising IgG antibody complexes can result in increased intracellular infection through idiosyncratic Fcγ-receptor signalling. The activation of Fcγ receptors usually leads to phagocytosis. Paradoxically, the ligation of monocyte or macrophage Fcγ receptors by IgG immune complexes, rather than aiding host defences, can suppress innate immunity, increase production of interleukin 10, and bias T-helper-1 (Th1) responses to Th2 responses, leading to increased infectious output by infected cells. This intrinsic antibody-dependent enhancement (ADE) of infection modulates the severity of diseases as disparate as dengue haemorrhagic fever and leishmaniasis. Intrinsic ADE is distinct from extrinsic ADE, whereby complexes of infectious agents with non-neutralising antibodies lead to an increased number of infected cells. Intrinsic ADE might be involved in many protozoan, bacterial, and viral infections. We review insights into intracellular mechanisms and implications of enhanced pathogenesis after ligation of macrophage Fcγ receptors by infectious immune complexes.

An Analysis of Saturable Absorbers

Abstract: This paper contains an analysis of the behavior of saturable filters, based on models with simple energy level structures. In this analysis, the effects of possible excited state absorption at the irradiating wavelength are considered and are shown to give rise to a nonsaturable component of the absorption coefficient. Expressions for the steady-state transmission of an optically thick saturable absorber, and for the temporal response of an optically thin absorber, are derived. The question of homogeneous vs inhomogeneous broadening of the absorption line is discussed, and it is suggested that spectral hole burning may occur in a thermally broadened line at a sufficiently high irradiance level. The desirable features of a saturable absorber for use in a Q-switched laser system are briefly described, and it is shown how the usual rate equations for a laser system may be amended to include the effects of an intracavity saturable filter.