5-s-Cysteinyl-conjugates of catecholamines induce cell damage,extensive DNA base modification and increases in caspase-3 activity in neurons

A decrease in reduced glutathione levels in dopamine containing nigral cells in Parkinson's disease may result from the formation of cysteinyl-adducts of catecholamines, which in turn exert toxicity on nigral cells. We show that exposure of neurons (CSM 14.1) to 5-S-cysteinyl conjugates of dopamine, L-DOPA, DOPAC or DHMA causes neuronal damage, increases in oxidative DNA base modification and an elevation of caspase-3 activity in cells. Damage to neurons was apparent 12-48 h of post-exposure and there were increases in caspase-3 activity in neurons after 6 h. These changes were paralleled by large increases in pyrimidine and purine base oxidation products, such as 8-OH-guanine suggesting that 5-S-cysteinyl conjugates of catecholamines are capable of diffusing into cells and stimulating the formation of reactive oxygen species (ROS), which may then lead to a mechanism of cell damage involving caspase-3. Indeed, intracellular ROS were observed to rise sharply on exposure to the conjugates. These results suggest one mechanism by which oxidative stress may occur in the substantia nigra in Parkinson's disease.     

Loss of oxidized and chlorinated bases in DNA treated with reactive oxygen species: implications for assessment of oxidative damage in vivo

Oxidative damage to DNA has been reported to occur in a wide variety of disease states. The most widely used "marker" for oxidative DNA damage is 8-hydroxyguanine. However, the use of only one marker has limitations. Exposure of calf thymus DNA to an .OH-generating system (CuCl(2), ascorbate, H(2)O(2)) or to hypochlorous acid (HOCl), led to the extensive production of multiple oxidized or chlorinated DNA base products, as measured by gas chromatography-mass spectrometry. The addition of peroxynitrite (ONOO(-)) (<200 microM) or SIN-1 (1mM) to oxidized DNA led to the extensive loss of 8-hydroxyguanine, 5-hydroxycytosine, 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 2-hydroxyadenine, 8-hydroxyadenine, and 4,6-diamino-5-formamidopyrimidine were lost at higher ONOO(-) concentrations (>200 microM). Exposure of DNA to HOCl led to the generation of 5-Cl uracil and 8-Cl adenine and addition of ONOO(-) (<200 microM) or SIN-1 (1mM) led to an extensive loss of 8-Cl adenine and a small loss of 5-Cl uracil at higher concentrations (>500 microM). An .OH-generating system (CuCl(2)/ascorbate/H(2)O(2)) could also destroy these chlorinated species. Treatment of oxidized or chlorinated DNA with acidified nitrite (NO(2)(-), pH 3) led to substantial loss of various base lesions, in particular 8-OH guanine, 5-OH cytosine, thymine glycol, and 8-Cl adenine. Our data indicate the possibility that when ONOO(-), nitrite in regions of low pH or .OH are produced at sites of inflammation, levels of certain damaged DNA bases could represent an underestimate of ongoing DNA damage. This study emphasizes the need to examine more than one modified DNA base when assessing the role of reactive species in human disease.     

Shedding light on melanoma

Not just confined to sunny places, the incidence of melanoma has been rising in all fair-skinned populations around the world. How much is known about the causes of this disease, and can this knowledge be applied to preventive strategies?     

Polymorphisms in Genes of Relevance for Oestrogen and Oxytocin Pathways and Risk of Barrett’s Oesophagus and Oesophageal Adenocarcinoma: A Pooled Analysis from the BEACON Consortium

Background

The strong male predominance in oesophageal adenocarcinoma (OAC) and Barrett’s oesophagus (BO) continues to puzzle. Hormonal influence, e.g. oestrogen or oxytocin, might contribute.

Methods

This genetic-epidemiological study pooled 14 studies from three continents, Australia, Europe, and North America. Polymorphisms in 3 key genes coding for the oestrogen pathway (receptor alpha (ESR1), receptor beta (ESR2), and aromatase (CYP19A1)), and 3 key genes of the oxytocin pathway (the oxytocin receptor (OXTR), oxytocin protein (OXT), and cyclic ADP ribose hydrolase glycoprotein (CD38)), were analysed using a gene-based approach, versatile gene-based test association study (VEGAS).

Results

Among 1508 OAC patients, 2383 BO patients, and 2170 controls, genetic variants within ESR1 were associated with BO in males (p = 0.0058) and an increased risk of OAC and BO combined in males (p = 0.0023). Genetic variants within OXTR were associated with an increased risk of BO in both sexes combined (p = 0.0035) and in males (p = 0.0012). We followed up these suggestive findings in a further smaller data set, but found no replication. There were no significant associations between the other 4 genes studied and risk of OAC, BO, separately on in combination, in males and females combined or in males only.

Conclusion

Genetic variants in the oestrogen receptor alpha and the oxytocin receptor may be associated with an increased risk of BO or OAC, but replication in other large samples are needed.     

Monocytes/macrophages express chemokine receptor CCR9 in rheumatoid arthritis and CCL25 stimulates their differentiation

Introduction  

Monocytes/macrophages accumulate in the rheumatoid (RA) synovium where they play a central role in inflammation and joint destruction. Identification of molecules involved in their accumulation and differentiation is important to inform therapeutic strategies. This study investigated the expression and function of chemokine receptor CCR9 in the peripheral blood (PB) and synovium of RA, non-RA patients and healthy volunteers.     

Microfilariae in Galápagos penguins (Spheniscus mendiculus) and flightless cormorants (Phalacrocorax harrisi): genetics, morphology, and prevalence

Galapagos penguins (Spheniscus mendiculus) and flightless cormorants (Phalacrocorax harrisi) live in small, isolated populations on the westernmost islands of Isabela and Fernandina in the Galápagos Islands, Ecuador. Between August 2003 and February 2005, 4 field trips, 2 in the cool, dry season (August 2003 and August 2004) and 2 in the hot, rainy season (March 2004 and February 2005), were undertaken; 298 Galápagos penguins and 380 cormorants were sampled for prevalence and intensity of hemoparasites. Microfilariae were found in both the penguins and the cormorants. Blood smears were negative for the presence of other species of hemoparasites. Overall prevalence of microfilariae across seasons was 42.0% in cormorants and 13.8% in the penguins. Intensity of infection was generally low (mean = 3.2-31.7 in 25 fields across seasons and species) with the exception of a few individuals with markedly high intensities of parasites (>300 in 25 fields in 1 cormorant). Prevalence of microfilariae increased significantly over the 4 sampling periods for cormorants, but not for penguins. Prevalences were significantly higher in cormorants than in penguins for 3 of the 4 collecting trips. Male penguins had higher prevalences than females; however, there were no gender differences in cormorants. No relation was detected between body mass and either presence or intensity of parasitism. Morphological characteristics of the microfilariae are also described and specimens from each host species were similar in all characters measured. DNA sequence data from the mitochondrial cytochrome c oxidase subunit I gene were consistent with the morphological evidence and together demonstrate that the penguins and cormorants are likely to be infected with the same species of microfilariae.     

A combination of naturally occurring mutations in North American West Nile virus nonstructural protein genes and in the 3' untranslated region alters virus phenotype

We previously reported mutations in North American West Nile viruses (WNVs) with a small-plaque (sp), temperature-sensitive (ts), and/or mouse-attenuated (att) phenotype. Using an infectious clone, site-directed mutations and 3' untranslated region (3'UTR) exchanges were introduced into the WNV NY99 genome. Characterization of mutants demonstrated that a combination of mutations involving the NS4B protein (E249G) together with either a mutation in the NS5 protein (A804V) or three mutations in the 3'UTR (A10596G, C10774U, A10799G) produced sp, ts, and/or att variants. These results suggested that the discovery of North American WNV-phenotypic variants is rare because of the apparent requirement of concurrent polygenic mutations.