Brain MRI and biological diagnosis in five Tunisians MLD patients

Metachromatic leukodystrophy (MLD) is a recessive autosomal disease which is characterized by an accumulation of sulfatides in the central and peripheral nervous system. It is due to the enzyme deficiency of the sulfatide sulfatase i.e. arylsulfatase A (ASA). we studied 5/200 cases of MLD and clearly distinguished three clinical forms. One of them presented the juvenile form; two presented the late infantile form; and two other presented the adult form. The Magnetic Resonance Imaging (MRI) of these patients showed a diffuse, bilateral and symmetrical demyelination. The biochemical diagnosis of MLD patients evidencing the low activity of ASA and sulfatide accumulation

The role of sulfoglucuronosyl glycosphingolipids in the pathogenesis of monoclonal IgM paraproteinemia and peripheral neuropathy

In IgM paraproteinemia and peripheral neuropathy, IgM M-protein secretion by B cells leads to a T helper cell response, suggesting that it is antibody-mediated autoimmune disease involving carbohydrate epitopes in myelin sheaths. An immune response against sulfoglucuronosyl glycosphingolipids (SGGLs) is presumed to participate in demyelination or axonal degeneration in the peripheral nervous system (PNS). SGGLs contain a 3-sulfoglucuronic acid residue that interacts with anti-myelin-associated glycoprotein (MAG) and the monoclonal antibody anti-HNK-1. Immunization of animals with sulfoglucuronosyl paragloboside (SGPG) induced anti-SGPG antibodies and sensory neuropathy, which closely resembles the human disease. These animal models might help to understand the disease mechanism and lead to more specific therapeutic strategies. In an in vitro study, destruction or malfunction of the blood-nerve barrier (BNB) was found, resulting in the leakage of circulating antibodies into the PNS parenchyma, which may be considered as the initial key step for development of disease

Determination of the electron energy distribution function in weakly ionized plasma by means of a Langmuir probe and numerical methods

International audienceNumerical methods are used to determine the Electron Energy Distribution Function (EEDF) from I(V) probe characteristics, which are measured using a cylindrical Langmuir probe in the case of weakly ionized plasmas. This task becomes difficult when measurement is complicated by the presence of an external magnetic field or in high pressure plasma because of collision between electrons and heavy particles within the sheath formed around the probe tip. In this case, the electron current must be calculated using the Swift law instead of the Langmuir law. The numerical methods consist of determining the derivative functions of the I(V) probe characteristics in the case of a noisy signal and correcting the EEDF taking into account the electron diffusion coefficient within the sheath formed around the probe collector. Algorithms are given to detail the methods step by step, which can be used to write homemade codes. The methods are tested in the case of different plasma reactors described in the literature, such as microwave plasma and rf (radio-frequency) and dc (direct current) plasma reactors working at different pressures with or without magnetic field. The results show the effect of pressure or magnetic field on the I(V) probe characteristics because of the change in the electron diffusion coefficient

Electron energy distribution function in a pulsed 2.45GHz hydrogen magnetoplasma: Study of the decay

This work is devoted to the study of the Electron Energy Distribution Function (EEDF) during the decay (afterglow) of a pulsed magnetoplasma working at 2.45GHz in H2. The experiments are performed under resonance (B=0.087T) and off resonance (B=0.120T) conditions, at low (0.38Pa) and high pressure (0.62Pa) for incoming power ranging from 300W to 1500W. At steady state i.e. before the discharge decay, the EEDF profile exhibits three main components of which amplitude changes under experimental conditions. A low energy component (εe<10eV) is observed whatever experimental conditions are. An intermediate energy component is observed at energy ranging from 5eV to 15eV under resonance conditions. A high energy component is observed up to 30eV in the EEDF tail, mainly under off resonance conditions. Standard fitting methods are used to study the change of the different EEDF components versus time during afterglow. We show that the three components stand for different times: The low and high energy component stand from 10μs to 15μs and the intermediate energy component stands for only 5μs. The different decay characteristic times are discussed and the results are correlated to the electron recombination processes in the discharge, to the reminiscent incoming power observed up to 30μs, and to the peak observed in the reflected power during decays. We show that the low energy component decay is due to the electron recombination process, which is limited by the charge transfer process which produces H3+