The effect of natriuretic C-type peptide and its change over time on mortality in patients on haemodialysis or haemodiafiltration

Background C-type natriuretic peptide (CNP) and its co-product N-terminal proCNP (NTproCNP) have been associated with beneficial effects on the cardiovascular system. In prevalent dialysis patients, however, a relation between NTproCNP and mortality has not yet been investigated. Furthermore, as a middle molecular weight substance, its concentration might be influenced by dialysis modality. Methods In a cohort of patients treated with haemodialysis (HD) or haemodiafiltration (HDF), levels of NTproCNP were measured at baseline and 6, 12, 24 and 36 months. The relation between serum NTproCNP and mortality and the relation between the 6-month rate of change of NTproCNP and mortality were analysed using Cox regression models. For the longitudinal analyses, linear mixed models were used. Results In total, 406 subjects were studied. The median baseline serum NTproCNP was 93 pmol/L and the median follow-up was 2.97 years. No relation between baseline NTproCNP or its rate of change over 6 months and mortality was found. NTproCNP levels remained stable in HD patients, whereas NTproCNP decreased significantly in HDF patients. The relative decline depended on the magnitude of the convection volume. Conclusions In our study, levels of NTproCNP appear strongly elevated in prevalent dialysis patients. Second, while NTproCNP remains unaltered in HD patients, its levels decline in individuals treated with HDF, with the decline dependent on the magnitude of the convection volume. Third, NTproCNP is not related to mortality in this population. Thus NTproCNP does not seem to be a useful marker for mortality risk in dialysis patients.

Hydroxyl Radical Generation by an Extracellular Low-Molecular-Weight Substance and Phenol Oxidase Activity During Wood Degradation by the White-Rot Basidiomycete Phanerochaete chrysosporium

SummaryThe mechanism of wood degradation by white-rot fungi is not understood in detail other than it is involving phenol oxidases (which are lignin-degrading enzymes) and cellulases. The possible role of hydroxyl radicals in degradation by the white-rot fungusPhanerochaete chrysosporiumwas studied. The production of a low-molecular-weight substance that is secreted was measured periodically. The substance catalyzes a redox reaction between O2and an electron donor producing hydroxyl radicals in the culture fluid of this fungus with glucose or wood as the carbon source. We examined the possible role(s) of one-electron oxidation activity by phenol oxidases and hydroxyl radicals in wood degradation by this fungus. Assays of phenol oxidase activity showed thatP. chrysosporiumproduced much manganese peroxidase in wood culture, and that the activity peaked early in incubation. The generation of hydroxyl radicals in the redox reaction was related to the rate of wood degradation, but the activity of phenol oxidases was not related. Therefore, hydroxyl radicals are important in wood degradation by this fungus.