Neutrophil superoxide-anion generating capacity in chronic smoking: Effect of long-term α-tocopherol therapy

We investigated whether long-term alpha-tocopherol therapy in chronic smoking affects superoxide generating capacity of neutrophils ex vivo. To this purpose, we randomly assigned 128 male chronic smokers (37 +/- 21 pack years of smoking) to treatment with placebo (n = 64) or alpha-tocopherol (400 IU dL-a-tocopherol daily, n = 64). After two years of therapy, we measured phorbol 12-myristate 13-acetate-induced superoxide production of isolated neutrophils and of diluted whole blood by monitoring reduction of ferricytochrome c and luminol-enhanced peroxidase-catalyzed chemiluminescence. Plasma lipids and lipoproteins were not different between the two treatment groups. As expected, concentrations of alpha-tocopherol in plasma and in low-density lipoproteins were markedly elevated in the supplemented group compared to the placebo group (+ 120%, P < 0.0001 and + 83%, P < 0.0001, respectively). Consequently, resistance to in vitro oxidation of low-density lipoproteins (reflected by lag time of conjugated diene formation) was higher in the supplemented group than in the placebo group (+ 22%, P < 0.0001). Superoxide generating capacity of neutrophils and superoxide production in diluted whole blood did not differ between alpha-tocopherol and placebo group. It is concluded that in chronic smoking long-term supranormal alpha-tocopherol intake does not reduce neutrophil superoxide-anion generating capacity, despite large increases in the concentrations of alpha-tocopherol in plasma and in low-density lipoproteins.     

Apoptosis in cardiac development

Cell degeneration, as a phenomenon accompanying developmental processes, was originally described over a century ago. Apoptosis, a term introduced approximately three decades ago, has occupied investigators particularly with respect to cell and tissue kinetics, emphasizing its role in the disposal of supernumerary, malinstructed or damaged cells. Although apoptosis is mostly related to developmental processes, evidence has been gathered indicating that it may also perform other roles. In this review, which concentrates on cardiac development, we examine focal apoptosis and subsequent signal cascades in combination with timed morphogenetic events. Apoptosis mainly occurs in the non-myocardial compartment of the embryonic heart, a compartment that consists of cells derived from the endocardium, the epicardium and the neural crest. The last-mentioned population invades the outflow tract and the atrioventricular endocardial cushions. The signalling cascade seems to involve the activation of latent transforming growth factor beta, resulting in cardiomyocyte migration and subsequent myocardialization of the endocardial cushions. Aberrant apoptosis accompanies cardiac anomalies. Furthermore, an apoptotic population is found surrounding the developing conduction system. A possible role for differentiation is suggested.     

Mitochondrial and cytosolic thiol redox state are not detectably altered in isolated human NADH:ubiquinone oxidoreductase deficiency

Isolated complex I deficiency is the most common enzymatic defect of the oxidative phosphorylation (OXPHOS) system, causing a wide range of clinical phenotypes. We reported before that the rates at which reactive oxygen species (ROS)-sensitive dyes are converted into their fluorescent oxidation products are markedly increased in cultured skin fibroblasts of patients with nuclear-inherited isolated complex I deficiency. Using video-imaging microscopy we show here that these cells also display a marked increase in NAD(P)H autofluorescence. Linear regression analysis revealed a negative correlation with the residual complex I activity and a positive correlation with the oxidation rates of the ROS-sensitive dyes 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein and hydroethidine for a cohort of 10 patient cell lines. On the other hand, video-imaging microscopy of cells expressing reduction-oxidation sensitive GFP1 in either the mitochondrial matrix or cytosol showed the absence of any detectable change in thiol redox state. In agreement with this result, neither the glutathione nor the glutathione disulfide content differed significantly between patient and healthy fibroblasts. Finally, video-rate confocal microscopy of cells loaded with C11-BODIPY(581/591) demonstrated that the extent of lipid peroxidation, which is regarded as a measure of oxidative damage, was not altered in patient fibroblasts. Our results indicate that fibroblasts of patients with isolated complex I deficiency maintain their thiol redox state despite marked increases in ROS production.     

Redox processes in recent sediments of the river Meuse, The Netherlands

Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO₃ in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.     

Soil phosphorus constrains biodiversity across European grasslands

Nutrient pollution presents a serious threat to biodiversity conservation. In terrestrial ecosystems, the deleterious effects of nitrogen pollution are increasingly understood and several mitigating environmental policies have been developed. Compared to nitrogen, the effects of increased phosphorus have received far less attention, although some studies have indicated that phosphorus pollution may be detrimental for biodiversity as well. On the basis of a dataset covering 501 grassland plots throughout Europe, we demonstrate that, independent of the level of atmospheric nitrogen deposition and soil acidity, plant species richness was consistently negatively related to soil phosphorus. We also identified thresholds in soil phosphorus above which biodiversity appears to remain at a constant low level. Our results indicate that nutrient management policies biased toward reducing nitrogen pollution will fail to preserve biodiversity. As soil phosphorus is known to be extremely persistent and we found no evidence for a critical threshold below which no environmental harm is expected, we suggest that agro‐environmental schemes should include grasslands that are permanently free from phosphorus fertilization.     

The Effect of the Interleukin‐1 Cytokine Family Members IL‐1F6 and IL‐1F8 on Adipocyte Differentiation

Obesity is characterized by chronic low‐grade inflammation originating from expanding adipose tissue. In the present study, we examined the adipogenic expression levels of IL‐1F6 and IL‐1F8, both members of the IL‐1 family of cytokines, and their effects on adipose tissue gene expression. Although IL‐1F6 is primarily present in adipose tissue resident macrophages and induced by inflammation, IL‐1F8 is absent. IL‐1F6, but not IL‐1F8, reduces adipocyte differentiation, as shown by a significant decrease in PPARγ gene expression. Finally, both IL‐1F6 and IL‐1F8 are able to induce inflammatory gene expression in mature adipocytes. In conclusion, we demonstrate for the first time that IL‐1F6 is present in adipose tissue and that IL‐1F6 and IL‐1F8 are involved in the regulation of adipose tissue gene expression. Importantly, IL‐1F6 inhibits PPARγ expression which may lead to reduced adipocyte differentiation suggesting metabolic effects of this cytokine.     

Structural rearrangements of sucrose phosphorylase from Bifidobacterium adolescentis during sucrose conversion

The reaction mechanism of sucrose phosphorylase from Bifidobacterium adolescentis (BiSP) was studied by site-directed mutagenesis and x-ray crystallography. An inactive mutant of BiSP (E232Q) was co-crystallized with sucrose. The structure revealed a substrate-binding mode comparable with that seen in other related sucrose-acting enzymes. Wild-type BiSP was also crystallized in the presence of sucrose. In the dimeric structure, a covalent glucosyl intermediate was formed in one molecule of the BiSP dimer, and after hydrolysis of the glucosyl intermediate, a beta-D-glucose product complex was formed in the other molecule. Although the overall structure of the BiSP-glucosyl intermediate complex is similar to that of the BiSP(E232Q)-sucrose complex, the glucose complex discloses major differences in loop conformations. Two loops (residues 336-344 and 132-137) in the proximity of the active site move up to 16 and 4 A, respectively. On the basis of these findings, we have suggested a reaction cycle that takes into account the large movements in the active-site entrance loops.