Combination of Iron Overload Plus Ethanol and Ischemia Alone Give Rise to the Same Endogenous Free Iron Pool

Iron overload aggravates tissue damage caused by ischemia and ethanol intoxication. The underlying mechanisms of this phenomenon are not yet clear. To clarify these mechanisms we followed free iron (“loosely” bound redox-active iron) concentration in livers from rats subjected to experimental iron overload, acute ethanol intoxication, and ex vivo warm ischemia. The levels of free iron in non-homogenized liver tissues, liver homogenates, and hepatocyte cultures were analyzed by means of EPR spectroscopy. Ischemia gradually increased the levels of endogenous free iron in liver tissues and in liver homogenates. The increase was accompanied by the accumulation of lipid peroxidation products. Iron overload alone, known to increase significantly the total tissue iron, did not affect either free iron levels or lipid peroxidation. Homogenization of iron-loaded livers, however, resulted in the release of a significant portion of free iron from endogenous depositories. Acute ethanol intoxication increased free iron levels in liver tissue and diminished the portion of free iron releasing during homogenization. Similarly to liver tissue, the primary hepatocyte culture loaded with iron in vitro released significantly more free iron during homogenization compared to non iron-loaded hepatocyte culture. Analyzing three possible sources of free iron release under these experimental conditions in liver cells, namely ferritin, intracellular transferrin-receptor complex and heme oxygenase, we suggest that redox active free iron is released from ferritin under ischemic conditions whereas ethanol and homogenization facilitate the release of iron from endosomes containing transferrin-receptor complexes.     

Helicobacter pylori CagA-dependent macrophage migration inhibitory factor produced by gastric epithelial cells binds to CD74 and stimulates procarcinogenic events

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that has recently been implicated in carcinogenesis. Helicobacter pylori, which is closely linked to gastric cancer, induces the gastric epithelium to produce proinflammatory cytokines, including MIF. MIF can bind to CD74, which we have previously shown to be highly expressed on the surface of gastric epithelial cells (GEC) during H. pylori infection. In this study, we sought to investigate the role of the H. pylori-induced MIF on epithelial proliferation and procarcinogenic events. Upon establishing a role for the H. pylori CagA virulence factor in MIF production, MIF binding to CD74 on GEC was confirmed. rMIF and H. pylori were shown to increase GEC proliferation, which was decreased when cagA- strains were used and when CD74 was blocked by mAbs. Apoptosis was also decreased by MIF, but increased by cagA- strains that induced much lower amounts of MIF than the wild-type bacteria. Furthermore, MIF binding to CD74 was also shown to decrease p53 phosphorylation and up-regulate Bcl-2 expression. This data describes a novel system in which an H. pylori virulence factor contributes to the production of a host factor that in turn up-regulates procarcinogenic events by the gastric epithelium.     

Molecular mechanisms of experience-dependent plasticity in visual cortex

A remarkable amount of our current knowledge of mechanisms underlying experience-dependent plasticity during cortical development comes from study of the mammalian visual cortex. Recent advances in high-resolution cellular imaging, combined with genetic manipulations in mice, novel fluorescent recombinant probes, and large-scale screens of gene expression, have revealed multiple molecular mechanisms that underlie structural and functional plasticity in visual cortex. We situate these mechanisms in the context of a new conceptual framework of feed-forward and feedback regulation for understanding how neurons of the visual cortex reorganize their connections in response to changes in sensory inputs. Such conceptual advances have important implications for understanding not only normal development but also pathological conditions that afflict the central nervous system.     

Effect of vitamin D3 on behavioural and biochemical parameters in diabetes type 1‐induced rats

Diabetes is associated with long‐term complications in the brain and reduced cognitive ability. Vitamin D₃ (VD₃) appears to be involved in the amelioration of hyperglycaemia in streptozotocin (STZ)‐induced diabetic rats. Our aim was to analyse the potential of VD₃ in avoiding brain damage through evaluation of acetylcholinesterase (AChE), Na⁺K⁺‐adenosine triphosphatase (ATPase) and delta aminolevulinate dehydratase (δ‐ALA‐D) activities and thiobarbituric acid reactive substance (TBARS) levels from cerebral cortex, as well as memory in STZ‐induced diabetic rats. Animals were divided into eight groups (n = 5): control/saline, control/metformin (Metf), control/VD₃, control/Metf + VD₃, diabetic/saline, diabetic/Metf, diabetic/VD₃ and diabetic/Metf + VD₃. Thirty days after treatment, animals were submitted to contextual fear‐conditioning and open‐field behavioural tests, after which they were sacrificed and the cerebral cortex was dissected. Our results demonstrate a significant memory deficit, an increase in AChE activity and TBARS levels and a decrease in δ‐ALA‐D and Na⁺K⁺‐ATPase activities in diabetic rats when compared with the controls. Treatment of diabetic rats with Metf and VD₃ prevented the increase in AChE activity when compared with the diabetic/saline group. In treated diabetic rats, the decrease in Na⁺K⁺‐ATPase was reverted when compared with non‐treated rats, but the increase in δ‐ALA‐D activity was not. VD₃ prevented diabetes‐induced TBARS level and improved memory. Our results show that VD₃ can avoid cognitive deficit through prevention of changes in important enzymes such as Na⁺K⁺‐ATPase and AChE in cerebral cortex in type 1 diabetic rats. Copyright © 2014 John Wiley & Sons, Ltd.     

Adiponectin expression in human epicardial adipose tissue in vivo is lower in patients with coronary artery disease

BACKGROUND: Intra-peritoneal adipose tissue is recognized as a predictor of metabolic syndrome and may contribute to the risk for cardiovascular disease by the production of adipocytokines, including adiponectin. Nevertheless, there is no knowledge on whether other visceral depots of adipose tissue, including the epicardial fat, have any metabolically active role, including production of adiponectin. AIM OF THE STUDY: We sought to evaluate adiponectin protein expression in epicardial adipose tissue in vivo both in patients with severe coronary artery disease (CAD) and in subjects without CAD. METHODS: Twenty-two patients were enrolled for the study. We selected 16 patients who underwent elective coronary artery bypass graft surgery for critical CAD, 5 who underwent surgery for valve replacement and 1 for correction of an interatrial defect. Epicardial adipose tissue biopsy samples were obtained before the initiation of cardiopulmonary bypass. Adiponectin protein level in epicardial adipose tissue was evaluated by Western blotting. RESULTS: Adiponectin protein value, expressed as adiponectin/actin ratio, in epicardial adipose tissue was significantly lower in patients with severe CAD than in those without CAD (1.42 +/- 0.77 vs 2.36 +/- 0.84 p = 0.02, 95% CI 0.64-1.74). CONCLUSIONS: This study showed for the first time that human epicardial adipose tissue expresses adiponectin. Adiponectin expression is significantly lower in epicardial fat isolated from patients with CAD.     

Porins facilitate nitric oxide-mediated killing of mycobacteria

Non-pathogenic mycobacteria such us Mycobacterium smegmatis reside in macrophages within phagosomes that fuse with late endocytic/lysosomal compartments. This sequential fusion process is required for the killing of non-pathogenic mycobacteria by macrophages. Porins are proteins that allow the influx of hydrophilic molecules across the mycobacterial outer membrane. Deletion of the porins MspA, MspC and MspD significantly increased survival of M. smegmatis in J774 macrophages. However, the mechanism underlying this observation is unknown. Internalization of wild-type M. smegmatis (SMR5) and the porin triple mutant (ML16) by macrophages was identical indicating that the viability of the porin mutant in vivo was enhanced. This was not due to effects on phagosome trafficking since fusion of phagosomes containing the mutant with late endocytic compartments was unaffected. Moreover, in ML16-infected macrophages, the generation of nitric oxide (NO) was similar to the wild type-infected cells. However, ML16 was significantly more resistant to the effects of NO in vitro compared to SMR5. Our data provide evidence that porins render mycobacteria vulnerable to killing by reactive nitrogen intermediates within phagosomes probably by facilitating uptake of NO across the mycobacterial outer membrane.     

Human TCR transgenic Bet v 1-specific Th1 cells suppress the effector function of Bet v 1-specific Th2 cells

Pollinosis to birch pollen is a common type I allergy in the Northern Hemisphere. Moreover, birch pollen-allergic individuals sensitized to the major birch pollen allergen Bet v 1 frequently develop allergic reactions to stone fruits, hazelnuts, and certain vegetables due to immunological cross-reactivity. The major T cell epitope Bet v 1(142-153) plays an important role in cross-reactivity between the respiratory allergen Bet v 1 and its homologous food allergens. In this study, we cloned and functionally analyzed a human αβ TCR specific for the immunodominant epitope Bet v 1(142-153). cDNAs encoding TCR α- and β-chains were amplified from a Bet v 1(142-153)-specific T cell clone, introduced into Jurkat T cells and peripheral blood T lymphocytes of allergic and nonallergic individuals, and evaluated functionally. The resulting TCR transgenic (TCRtg) T cells responded in an allergen-specific and costimulation-dependent manner to APCs either pulsed with Bet v 1(142-153) peptide or coexpressing invariant chain::Bet v 1(142-153) fusion proteins. TCRtg T cells responded to Bet v 1-related food and tree pollen allergens that were processed and presented by monocyte-derived dendritic cells. Bet v 1(142-153)-presenting but not Bet v 1(4-15)-presenting artificial APCs coexpressing membrane-bound IL-12 polarized allergen-specific TCRtg T cells toward a Th1 phenotype, producing high levels of IFN-γ. Coculture of such Th1-polarized T cells with allergen-specific Th2-differentiated T cells significantly suppressed Th2 effector cytokine production. These data suggest that human allergen-specific TCR can transfer the fine specificity of the original T cell clone to heterologous T cells, which in turn can be instructed to modulate the effector function of the disease initiating/perpetuating allergen-specific Th2-differentiated T cells.     

β-Amino acid residues: Conformational characterization of an N- and C-protected homo-β-(S)-leucine

Summary An N- and C-protected derivative ofhomo-β-leucine, Fmoc-homo-β-(S)-leucine methyl ester, synthesized from the corresponding proteinogenic parent α-amino acid in enantiopure form has been fully characterized in the solid state by X-ray diffraction analysis. The crystal conformation of this new residue indicates and extended conformation for thishomo-β-residue, with the ϕ torsion angle being more constrained than the μ and ψ angles.