Lipid peroxidation products like malondialdehyde, 4-hydroxynonenal and F 2 -isoprostanes are widely used as markers of oxidative stress in vitro and in vivo . This study reports the results of a multi-laboratory validation study by COST Action B35 to assess inter-laboratory and intra-laboratory variation in the measurement of lipid peroxidation. Human plasma samples were exposed to UVA irradiation at different doses (0, 15 J, 20 J), encoded and shipped to 15 laboratories, where analyses of malondialdehyde, 4-hydroxynonenal and isoprostanes were conducted. The results demonstrate a low within-day-variation and a good correlation of results observed on two different days. However, high coeffi cients of variation were observed between the laboratories. Malondialdehyde determined by HPLC was found to be the most sensitive and reproducible lipid peroxidation product in plasma upon UVA treatment. It is concluded that measurement of malondialdehyde by HPLC has good analytical validity for inter-laboratory studies on lipid peroxidation in human EDTA-plasma samples, although it is acknowledged that this may not translate to biological validity.

In the present study we have evaluated the effect of a single hemodialysis session on the brain-derived neurotrophic factor levels in plasma [BDNF](pl) and in serum [BDNF](s) as well as on the plasma isoprostanes concentration [F(2) isoprostanes](pl), plasma total antioxidant capacity (TAC) and plasma cortisol levels in chronic kidney disease patients. Twenty male patients (age 69.8 ± 2.9 years (mean ± SE)) with end-stage renal disease undergoing maintenance hemodialysis on regular dialysis treatment for 15-71 months participated in this study. A single hemodialysis session, lasting 4.2 ± 0.1 h, resulted in a decrease (P = 0.014) in [BDNF](s) by ~42 % (2,574 ± 322 vs. 1,492 ± 327 pg ml(-1)). This was accompanied by an increase (P< 10(-4)) of [F(2)-Isoprostanes](pl) (38 ± 3 vs. 116 ± 16 pg ml(-1)), decrease (P < 10(-4)) in TAC (1,483 ± 41 vs. 983 ± 35 trolox equivalents, μmol l(-1)) and a decrease (P = 0.004) in plasma cortisol level (449.5 ± 101.2 vs. 315.3 ± 196.3 nmol l(-1)). No changes (P > 0.05) in [BDNF](pl) and the platelets count were observed after a single dialysis session. Furthermore, basal [BDNF](s) in the chronic kidney disease patients was significantly lower (P = 0.03) when compared to the age-matched control group (n = 23). We have concluded that the observed decrease in serum BDNF level after hemodialysis accompanied by elevated [F(2)-Isoprostanes](pl) and decreased plasma TAC might be caused by enhanced oxidative stress induced by hemodialysis.

Mutations in the DHCR24 gene, which encodes the cholesterol biosynthesis enzyme 3ß-hydroxysterol-∆24 reductase, result in an autosomal recessive disease called desmosterolosis. Further, reduced expression of DHCR24 is found in the temporal cortex of Alzheimer's disease patients. This suggests that variability in the regulatory regions of DHCR24 may contribute to the development of this neurodegenerative disease. In this work, we functionally characterised the proximal fragment of the human DHCR24 gene, for the first time. We show that the transcription of DHCR24 is initiated from a single CpG-rich promoter that is regulated by DNA methylation in some cell types. An activator sequence was also uncovered in the -1203/-665 bp region by reporter gene assays. Furthermore, sodium butyrate (a well-known HDAC inhibitor) increased DHCR24 expression in SH-SY5Y cells by recruiting acetylated core histones H3 and H4 to the enhancer region, as demonstrated by transient transfection and chromatin immunoprecipitation assays. Understanding the regulation of the DHCR24 gene may lead to alternative therapeutic strategies in at least some Alzheimer's patients.

There are several barriers to the application of dendriplexes formed by poly(propylene imine) dendrimers and genetic material for gene therapy. One limitation is their interaction with extracellular matrix components such as glucosaminoglycans. These can displace the genetic material from the dendriplexes, affecting their transfection activity. In this study, we analyzed the interaction between dendriplexes and the four main glucosaminoglycans (heparin, heparan sulfate, chondroitin sulfate, and hyaluronic acid) by fluorescence polarization and gel electrophoresis. Dendriplexes were formed by combining three anti-HIV antisense oligodeoxynucleotides with three poly(propylene imine) dendrimers of the fourth generation: unmodified and partially modified with maltose and maltotriose (open shell glycodendrimers). The data showed that the effect of glucosaminoglycans on dendriplexes depends on the glucosaminoglycan type and the oligosaccharide serving as the surface group of the dendrimer. Heparin at physiological concentrations destroys dendriplexes formed by open shell glycodendrimers, but dendriplexes based on unmodified poly(propylene imine) dendrimers are stable in its presence. The other glucosaminoglycans at physiological concentrations cannot destroy dendriplexes formed by any of the dendrimers studied.

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