T-cell regulation in Erythema Nodosum Leprosum.

Leprosy is a disease caused by Mycobacterium leprae where the clinical spectrum correlates with the patient immune response. Erythema Nodosum Leprosum (ENL) is an immune-mediated inflammatory complication, which causes significant morbidity in affected leprosy patients. The underlying cause of ENL is not conclusively known. However, immune-complexes and cell-mediated immunity have been suggested in the pathogenesis of ENL. The aim of this study was to investigate the regulatory T-cells in patients with ENL. Forty-six untreated patients with ENL and 31 non-reactional lepromatous leprosy (LL) patient controls visiting ALERT Hospital, Ethiopia were enrolled to the study. Blood samples were obtained before, during and after prednisolone treatment of ENL cases. Peripheral blood mononuclear cells (PBMCs) were isolated and used for immunophenotyping of regulatory T-cells by flow cytometry. Five markers: CD3, CD4 or CD8, CD25, CD27 and FoxP3 were used to define CD4+ and CD8+ regulatory T-cells. Clinical and histopathological data were obtained as supplementary information. All patients had been followed for 28 weeks. Patients with ENL reactions had a lower percentage of CD4+ regulatory T-cells (1.7%) than LL patient controls (3.8%) at diagnosis of ENL before treatment. After treatment, the percentage of CD4+regulatory T-cells was not significantly different between the two groups. The percentage of CD8+ regulatory T-cells was not significantly different in ENL and LL controls before and after treatment. Furthermore, patients with ENL had higher percentage of CD4+ T-ells and CD4+/CD8+ T-cells ratio than LL patient controls before treatment. The expression of CD25 on CD4+ and CD8+ T-cells was not significantly different in ENL and LL controls suggesting that CD25 expression is not associated with ENL reactions while FoxP3 expression on CD4+ T-cells was significantly lower in patients with ENL than in LL controls. We also found that prednisolone treatment of patients with ENL reactions suppresses CD4+ T-cell but not CD8+ T-cell frequencies. Hence, ENL is associated with lower levels of T regulatory cells and higher CD4+/CD8+ T-cell ratio. We suggest that this loss of regulation is one of the causes of ENL

Physically Similar Systems - A History of the Concept

PreprintThe concept of similar systems arose in physics, and appears to have originated with Newton in the seventeenth century. This chapter provides a critical history of the concept of physically similar systems, the twentieth century concept into which it developed. The concept was used in the nineteenth century in various fields of engineering (Froude, Bertrand, Reech), theoretical physics (van der Waals, Onnes, Lorentz, Maxwell, Boltzmann) and theoretical and experimental hydrodynamics (Stokes, Helmholtz, Reynolds, Prandtl, Rayleigh). In 1914, it was articulated in terms of ideas developed in the eighteenth century and used in nineteenth century mathematics and mechanics: equations, functions and dimensional analysis. The terminology physically similar systems was proposed for this new characterization of similar systems by the physicist Edgar Buckingham. Related work by Vaschy, Bertrand, and Riabouchinsky had appeared by then. The concept is very powerful in studying physical phenomena both theoretically and experimentally. As it is not currently part of the core curricula of STEM disciplines or philosophy of science, it is not as well known as it ought to be

Identification of simultaneously active partial discharge sources using combined radio frequency and IEC60270 measurement

Using a newly developed measurement system, partial discharge (PD) activity has been recorded simultaneously on a pulse-by-pulse basis in terms of radiated radio frequency (RF) energy and the conducted apparent charge measured according to the IEC60270 standard. Two epoxy resin insulation samples containing voids have been activated separately and in parallel and the resulting PD was measured using the combined system. It has been shown that the combined measurement system has the ability to distinguish between discharges occurring simultaneously in each of the respective samples. This is evident in the appearance of separate clusters when the energy of the radio frequency discharge signal is plotted against the apparent charge for a large number of pulses. The identity of the defect producing each cluster has been confirmed by modelling the complete response of a gas-insulated-switchgear chamber to simulated Gaussian current pulses of known charge. The combined technique has also shown potential to distinguish between additional simultaneously active defects, including free metallic particles in oil. The combination of the two measurement systems may enable the classification of PD activity with a greater degree of confidence than conventional phase-resolved measurements allow when more than one defect is present

Chemical and physical changes observed in poly(oxy-1,4 phenylsulfonyl-1,4 phenylene) following electrical stressing

High voltage insulation failure can arise because of the physical and chemical properties of the material and intrinsic changes through use, aging and weathering. Overall aging is believed to produce localised defects and structural points which eventually fail under electrical stressing. This paper will present FT-IR and AFM evidence to show some of the chemical and physical changes in the insulating polymer, poly(oxy-1,4 phenylsulfonyl-1,4 phenylene) (PES) when subjected to short duration high voltage electric discharge activity in the air above the surface of the polymer film