Academic literature on the topic 'Pathophysiologie du cil'

The pathophysiology, clinical approach, and management of the common causes of metabolic acidosis and alkalosis are discussed. In metabolic acidosis, a quantitative estimate of the extracellular volume (ECFV) is required to determine its content of bicarbonate in a patient with ECFV contraction. Buffering of H+ must occur by the bicarbonate buffer system in muscle to avoid binding to intracellular proteins, this requires low muscle capillary PCO2; acid gain type of metabolic acidosis is detected by the finding of new anions in blood and/or urine. The urine osmolal gap is the best indirect test

This chapter reviews the metabolism of homocysteine and its associated defects, focusing on the clinical manifestations of cognitive and behavioral disturbances. The terminology of homocysteine and its derivatives can be confusing, so I begin by clarifying that. Next, the metabolism of homocysteine is outlined, followed by discussion of the disorders of homocysteine transsulfuration. Vitamin B12 (cobalamin, CBL) is important in the effective metabolism of homocysteine and thus defects of CBL absorption, transport, and intracellular transport are also discussed. Finally, disorders of remethylation of methionine will be described. Diagnostic criteria, imaging results, and the pathophysiology of these disorders are also considered. The terminology related to homocysteine metabolism can be confusing. In 2000, a consensus statement on homocysteine nomenclature was published (Mudd et al. 2000). Normal human plasma contains total concentrations of homocysteine and its derivative disulfides of less than 15 μmol/L, although there is some variation due to genetic and other factors. Of this total, only 1%–2% occurs as the thiol (i.e., sulfhydryl) containing amino acid homocysteine. The remaining 98% is in the form of disulfides. Approximately 75%–80% of the total is bound to protein through disulfide bonds with protein cysteines, mainly in albumin, whereas the remainder occurs in non–protein-bound or free forms: the disulfide homocystine-homocystine (Hcy-Hcy), homocysteine-cysteine mixed disulphide, and minor amounts of other mixed disulfides. Together all these moieties make up what is referred to as total homocysteine (tHcy). As all these disulfide bonds can be cleaved by reducing agents, giving the thiol homocysteine, this allows measurement of tHcy as the sum of any thiol homocysteine originally present plus that originally present as a disulfide. In patients with homocystinuria, the percentage contribution of the thiol homocysteine to the total of these forms in plasma rises, reaching 10%–25% as the total homocysteine concentration reaches 150–400 μmol/L. The methionine/homocysteine cycle, also known as the single carbon transfer pathway, is found in all tissues and can broadly be divided into transsulfuration and remethylation components. The cycle aims to conserve methionine and provide sufficient S-adenosylmethionine (AdoMet) for vital transmethylation reactions.

Plasmin and leucocyte elastase are regarded as the two medically most important fibrin(ogen)-degrading proteolytic enzymes. There is, however, a considerable difference in information available about the cleavage specificities and fragmentation pathways of these two enzymes. Degradation by plasmin has been studied already for a long time in great detail so that now the time course of the degradation, the cleavage sites and the functional properties of many fragments are well known. In contrast, relatively little is known about the degradation by leucocyte elastase, except that the overall clea

ITP is an autoantibody-mediated disease which would logically be treated by decreasing the level of autoantibody. However, the most exciting developments in understanding the pathophysiology of the thrombocytopenia and its treatment involve a better understanding of the MPS FcR system and ways in which it can be modulated. This work has focussed on phagocytic paralysis or FcR blockade (FcRBl): the slowing of destruction of antibody-coated platelets despite the persistent presence of antibody on the surface of the platelet.Several areas have been explored in learning about the MPS system. Inves