In patients with acute renal failure, serum levels of linezolid can be reduced to the subtherapeutic range following renal replacement therapy.

The present study, conducted in a small group of subjects, shows that in critically ill patients with ARF on a nitrogen intake of 0.25 g/kg/day, an energy provision of 40 kcal/kg/day does not improve nitrogen balance estimates compared with a 30 kcal/kg/day intake; instead, it may increase the risk of artificial nutrition-related side-effects.

Enteral nutrition is a safe and effective nutritional technique to deliver artificial nutrition in ARF patients. Parenteral amino acid supplementation may be required, especially in patients with ARF needing renal replacement therapy.

Objective. Fibroblast activation is a crucial event in the development of systemic sclerosis (SSc). Antifibroblast autoantibodies (AFAs), detectable in the sera of SSc patients, are able to induce a proinflammatory phenotype on cultured fibroblasts. This study was undertaken to investigate the mechanisms of the interaction between AFAs and living fibroblasts.Methods. We coupled to fluorescein 1) IgG purified from AFA-positive and AFA-negative SSc sera (as assessed by cellular enzyme-linked immunosorbent assay) and 2) single healthy donor and pooled normal IgG. The interaction of IgG with living cultured fibroblasts from healthy individuals and from a patient with SSc was visualized by real-time confocal microscopy. Intracellular colocalization of caveolin and internalized AFApositive IgG was assessed by immunofluorescence.Results. AFA-positive IgG bound to living fibroblasts and was internalized with a cytoplasmic fibrillar pattern, in contrast to AFA-negative IgG. In the IgG tested, no correlation with antinuclear antibody activity was found. Preincubation of fibroblasts with normal IgG did not affect internalization. Internalized AFApositive IgG colocalized with caveolin, and internalization was entirely inhibited by disassembling fibroblast caveolae with filipin.Conclusion. The finding that both normal and pathologic fibroblasts specifically internalized AFApositive, but not AFA-negative, IgG demonstrates that AFAs in SSc patient sera interact with constitutively expressed membrane molecules on fibroblasts, via an Fc-independent mechanism. The results of colocalization and inhibition experiments suggest that microdomains containing caveolin are involved in the interaction between AFAs and fibroblasts. These data, together with the reported ability of AFAs to activate fibroblasts, provide evidence for a role of AFAs in the pathogenesis of SSc.

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