Divergent modulation of neuronal differentiation by caspase-2 and -9

Human Ntera2/cl.D1 (NT2) cells treated with retinoic acid (RA) differentiate towards a well characterized neuronal phenotype sharing many features with human fetal neurons. In view of the emerging role of caspases in murine stem cell/neural precursor differentiation, caspases activity was evaluated during RA differentiation. Caspase-2, -3 and -9 activity was transiently and selectively increased in differentiating and non-apoptotic NT2-cells. SiRNA-mediated selective silencing of either caspase-2 (si-Casp2) or -9 (si-Casp9) was implemented in order to dissect the role of distinct caspases. The RA-induced expression of neuronal markers, i.e. neural cell adhesion molecule (NCAM), microtubule associated protein-2 (MAP2) and tyrosine hydroxylase (TH) mRNAs and proteins, was decreased in si-Casp9, but markedly increased in si-Casp2 cells. During RA-induced NT2 differentiation, the class III histone deacetylase Sirt1, a putative caspase substrate implicated in the regulation of the proneural bHLH MASH1 gene expression, was cleaved to a ～100 kDa fragment. Sirt1 cleavage was markedly reduced in si-Casp9 cells, even though caspase-3 was normally activated, but was not affected (still cleaved) in si-Casp2 cells, despite a marked reduction of caspase-3 activity. The expression of MASH1 mRNA was higher and occurred earlier in si-Casp2 cells, while was reduced at early time points during differentiation in si-Casp9 cells. Thus, caspase-2 and -9 may perform opposite functions during RA-induced NT2 neuronal differentiation. While caspase-9 activation is relevant for proper neuronal differentiation, likely through the fine tuning of Sirt1 function, caspase-2 activation appears to hinder the RA-induced neuronal differentiation of NT2 cells.     

Genetic differences in internal transcribed spacer 1 between Dermanyssus gallinae from wild birds and domestic chickens

We investigated the presence of the poultry red mite or the chicken mite, Dermanyssus gallinae De Geer, Acari: Dermanyssidae, in wild bird populations in four different geographical regions of Sweden. The mites identified as D. gallinae were compared genetically with D. gallinae from egg-producing poultry farms in the same regions. The small subunit (SSU) gene, the 5.8S ribosomal RNA (rRNA) gene and the two internal transcribed spacers (ITS) of the rRNA genes were used in the genetic analysis. All D. gallinae mites had identical SSU rRNA, 5.8S rRNA and ITS2 sequences independent of their origin. By contrast, we identified significant differences in the ITS1 sequences. Based on the differences in the ITS1 sequences, the mites could be divided into two genotypes, of wild and domesticated origin, with no variation within the groups. These results imply that wild bird populations are of low importance, if any, as natural reservoirs of D. gallinae in these four geographical regions of Sweden.     

Immune responses against oxidative stress-derived antigens are associated with increased circulating tumor necrosis factor-alpha in heavy drinkers

Growing evidence indicates that pro-inflammatory cytokines play a key role in alcoholic liver disease (ALD). This study investigates whether immune response toward oxidative stress-derived antigens could be involved in promoting cytokine production in alcohol abusers. Cytokine profile and circulating IgG against human serum albumin modified by malondialdehyde (MDA-HSA) and against oxidized cardiolipin (Ox-CL) were evaluated in 59 heavy drinkers (HD) with (n=30) or without (n=29) ALD and 34 healthy controls. IgG against MDA-HSA and Ox-CL were significantly higher in HD with ALD than in HD without liver injury or healthy controls. The elevation of these antibodies was associated with higher circulating levels of IL-2 (p=0.005) and TNF-alpha (p=0.001), but not of IL-6 or IL-8. The prevalence of abnormal TNF-alpha was 5-fold higher in HD with oxidative stress-induced IgG than in those without. HD with the combined elevation of both TNF-alpha and oxidative stress-induced IgG had 11-fold (OR 10.7; 95%CI 1.2-97.2; p=0.023) greater risk of advanced ALD than those with high TNF-alpha, but no immune responses. Moreover, the combined elevation of TNF-alpha and lipid peroxidation-derived IgG was an independent predictor of ALD in HD. We propose that immune responses towards oxidative stress-derived antigen promote TNF-alpha production and contribute to liver damage in alcohol abusers.     

Biomonitoring of DNA damage in peripheral blood lymphocytes of subjects with dental restorative fillings

Dental fillings provide a major iatrogenic exposure to xenobiotic compounds due to the high prevalence of surface restorations in developed countries. Experimental data suggest that both amalgams, which contain mercury, and resin-based dental materials cause an impairment of the cellular pro- and anti-oxidant redox balance. The aim of this study was to assess the potential genotoxicity of dental restorative compounds in peripheral blood lymphocytes of young exposed subjects compared with controls. The study examined, by use of the comet assay, 68 carefully selected subjects taking into account the major known confounding factors. In the 44 exposed subjects, the mean numbers of restored surfaces was 3.0 and 3.8 in males and females, respectively. Tail length, percentage of DNA in the tail, tail moment or Olive tail moment were twofold higher in the exposed group than in unexposed controls, with significant differences. No significant difference was observed between amalgam and composite fillings. Furthermore, as shown by multivariate analysis, the association between dental fillings and DNA damage was enhanced by the number of fillings and by the exposure time. Among the lifestyle variables, a moderate physical activity showed a protective effect, being inversely correlated to the DNA damage parameters evaluated. On the whole, the use of DNA-migration allowed us to detect for the first time the potential adverse impact on human health of both kinds of dental filling constituents, the amalgams and the methacrylates. The main mechanism underlying the genotoxicity of dental restorative materials of various nature may be ascribed to the ability of both amalgams and methacrylates to trigger the generation of cellular reactive oxygen species, able to cause oxidative DNA lesions.     

Biomonitoring of DNA damage in peripheral blood lymphocytes of subjects with dental restorative fillings

Dental fillings provide a major iatrogenic exposure to xenobiotic compounds due to the high prevalence of surface restorations in developed countries. Experimental data suggest that both amalgams, which contain mercury, and resin-based dental materials cause an impairment of the cellular pro- and anti-oxidant redox balance. The aim of this study was to assess the potential genotoxicity of dental restorative compounds in peripheral blood lymphocytes of young exposed subjects compared with controls. The study examined, by use of the comet assay, 68 carefully selected subjects taking into account the major known confounding factors. In the 44 exposed subjects, the mean numbers of restored surfaces was 3.0 and 3.8 in males and females, respectively. Tail length, percentage of DNA in the tail, tail moment or Olive tail moment were twofold higher in the exposed group than in unexposed controls, with significant differences. No significant difference was observed between amalgam and composite fillings. Furthermore, as shown by multivariate analysis, the association between dental fillings and DNA damage was enhanced by the number of fillings and by the exposure time. Among the lifestyle variables, a moderate physical activity showed a protective effect, being inversely correlated to the DNA damage parameters evaluated. On the whole, the use of DNA-migration allowed us to detect for the first time the potential adverse impact on human health of both kinds of dental filling constituents, the amalgams and the methacrylates. The main mechanism underlying the genotoxicity of dental restorative materials of various nature may be ascribed to the ability of both amalgams and methacrylates to trigger the generation of cellular reactive oxygen species, able to cause oxidative DNA lesions.     

Changes in ultrastructure and the occurrence of permeability transition in mitochondria during rat liver regeneration.

Mitochondrial bioenergetic impairment has been found in the organelles isolated from rat liver during the prereplicative phase of liver regeneration. To gain insight into the mechanism underlying this impairment, we investigated mitochondrial ultrastructure and membrane permeability properties in the course of liver regeneration after partial hepatectomy, with special interest to the role played by Ca2+ in this process. The results show that during the first day after partial hepatectomy, significant changes in the ultrastructure of mitochondria in situ occur. Mitochondrial swelling and release from mitochondria of both glutamate dehydrogenase and aspartate aminotransferase isoenzymes with an increase in the mitochondrial Ca2+ content were also observed. Cyclosporin-A proved to be able to prevent the changes in mitochondrial membrane permeability properties. At 24 h after partial hepatectomy, despite alteration in mitochondrial membrane permeability properties, no release of cytochrome c was found. The ultrastructure of mitochondria, the membrane permeability properties and the Ca2+ content returned to normal values during the replicative phase of liver regeneration. These results suggest that, during the prereplicative phase of liver regeneration, the changes in mitochondrial ultrastructure observed in liver specimens were correlated with Ca2+-induced permeability transition in mitochondria.     

Young transgenic hMTH1 mice are protected against dietary fat‐induced metabolic stress—implications for enhanced longevity

hMTH1 protects against mutation during oxidative stress. It degrades 8‐oxodGTP to exclude potentially mutagenic oxidized guanine from DNA. hMTH1 expression is linked to ageing. Its downregulation in cultured cells accelerates RAS‐induced senescence, and its overexpression in hMTH1‐Tg mice extends lifespan. In this study, we analysed the effects of a brief (5 weeks) high‐fat diet challenge (HFD) in young (2 months old) and adult (7 months old) wild‐type (WT) and hMTH1‐Tg mice. We report that at 2 months, hMTH1 overexpression ameliorated HFD‐induced weight gain, changes in liver metabolism related to mitochondrial dysfunction and oxidative stress. It prevented DNA damage as quantified by a comet assay. At 7 months old, these HFD‐induced effects were less severe and hMTH1‐Tg and WT mice responded similarly. hMTH1 overexpression conferred lifelong protection against micronucleus induction, however. Since the canonical activity of hMTH1 is mutation prevention, we conclude that hMTH1 protects young mice against HFD by reducing genome instability during the early period of rapid growth and maximal gene expression. hMTH1 protection is redundant in the largely non‐growing, differentiated tissues of adult mice. In hMTH1‐Tg mice, expression of a less heavily mutated genome throughout life provides a plausible explanation for their extended longevity.     

Similar Occurrence of Febrile Episodes Reported in Non-Atopic Children at Three to Five Years of Age after Prebiotics Supplemented Infant Formula

This is a follow up study of a multicenter randomised placebo-controlled trial in seven centres in five West European countries. The RCT assessed the effect of infant formula supplemented with a mixture of prebiotics (with neutral short-chain and long-chain oligosaccharides and pectin-derived acidic oligosaccharides) during infancy in term-born children (n=1130). In the follow-up study 672 children (60% of the study population) participated: 232 (56%) from the prebiotics group (PG), 243 (58%) from the control group (CG), and 197 (66%) from the non-randomised breast-fed group (BG). The primary outcome was the occurrence of febrile episodes at three to five years of age prospectively documented by the parents: in the PG 1.17 (interquartile range 0.50-2.08) episodes per year versus 1.20 (0.52-2.57) in the CG; and 1.48 (0.65-2.60) in the BG. This specific prebiotics mixture given during infancy in healthy non-atopic subjects does not decrease febrile episodes and therefore seems not to prevent infection between their third and fifth birthday.     

Brownian dynamics simulations of supercoiled DNA with bent sequences.

The recently presented Brownian dynamics model for superhelical DNA is extended to include local curvature of the DNA helix axis. Here we analyze the effect of a permanent bend on the structure and dynamics of an 1870-bp superhelix with delta Lk = -10. Furthermore, we define quantitative expressions for computing structural parameters such as loop positions, superhelix diameter, and plectonemic content for trajectories of superhelical DNA, and assess the convergence toward global equilibrium. The structural fluctuations in an interwound superhelix, as reflected in the change in end loop positions, seem to occur by destruction/creation of loops rather than by a sliding motion of the DNA around its contour. Their time scale is on the order of 30-100 microseconds. A permanent bend changes the structure and the internal motions of the DNA drastically. The position of the end loop is fixed at the permanent bend, and the local motions of the chain are enhanced near the loops. A displacement of the bend from the end loop to a position inside the plectonemic part of the superhelix results in the formation of a new loop and the disappearance of the old one; we estimate the time involved in this process to be about 0.5 ms.