Association between mercury in cord serum and sex-specific DNA methylation in cord tissues.

Prenatal exposure to mercury in utero causes abnormal foetal growth and adverse outcomes. DNA methylation is currently considered a possible mechanism through which this occurs. However, few studies have investigated the association between prenatal exposure to mercury and DNA methylation in detail. This study aimed to clarify the relationship between prenatal exposure to total mercury (Hg) and DNA methylation and its associations with sex-specific characteristics in male and female offspring. In a birth cohort study known as the Chiba study of Mother and Child Health, the DNA methylation status in cord tissue and Hg concentrations in cord serum were examined. A total of 67 participants (27 males and 40 females) were analysed based on Spearman's correlations, adjusted by a false discovery rate of the sex of each offspring. Only one methylated locus was positively correlated with Hg concentrations in cord serum in male offspring, but not in female offspring, and was annotated to the haloacid dehalogenase-like hydrolase domain-containing protein 1 (HDHD1) gene on chromosome X. This locus was located in the intron of the HDHD1 gene body and is a binding site for the zinc finger protein CCCTC-binding factor. One of the other loci, located in HDHD1, was highly methylated in the group with higher mercury concentrations, and this locus was in the gene body of HDHD1. Our results suggest that prenatal exposure to Hg might affect the epigenetic status of male foetuses.

Diphenyl diselenide modulates nucleotidases, reducing inflammatory responses in the liver of Toxoplasma gondii-infected mice.

The aim of this study was to verify the effect of diphenyl diselenide (PhSe)2 on hepatic nucleotidases and on the concentration of purines in mice infected by Toxoplasma gondii. The animals were divided into four groups: Group A (uninfected), Group B (uninfected and treated with (PhSe)2), Group C (infected), and Group D (infected and treated with (PhSe)2). The inoculation (groups C and D) was performed with 50 cysts of T. gondii (ME-49 strain). Mice from groups B and D were treated with 5 µmol kg-1 of (PhSe)2. Liver tissue from infected mice showed less severe inflammation, elevated ATP/ADO ratio, elevated NTPDase, 5'nucleotidase, and ADA activities compared to the uninfected group (Group A; P < 0.05). However, infected and treated mice showed decreased ATP levels and elevated ADO levels, as well as higher NTPDase and 5'nucleotidase activities and decreased ADA activity in the hepatic tissue compared to the infected group (P < 0.05). Moreover, the (PhSe)2 treatment of infected mice reduced the hepatic inflammation and showed an immunomodulatory effect on ectonucleotidases of hepatic lymphocytes, which it returned to basal levels. Therefore, chronic infection by T. gondii induces hepatic inflammation in mice, and it is possible that purine levels and nucleotidase activities in hepatic tissue are related to the pathogenesis of the infection in this tissue. The treatment with (PhSe)2 was able to reverse the hepatic inflammation in mice chronically infected, possibly due to the modulation of purinergic enzymes that produce an anti-inflammatory profile through the purinergic system in the liver tissue.

Leishmania chagasi: an ecto-3'-nucleotidase activity modulated by inorganic phosphate and its possible involvement in parasite-macrophage interaction.

In this work we showed that living cells of Leishmania chagasi was able to hydrolyse 3'AMP 10 times more than 5'AMP. When parasites were grown in a low phosphate concentration (2 mM) the cellular proliferation decreased by 50% compared to cells grown in the presence of a high phosphate concentration (80 mM). However, the ecto-3'nucleotidase activity was 2-fold higher when L. chagasi was grown in a low phosphate concentration. This modulation observed on ecto-3'nucleotidase activity was not observed on ecto-5'nucleotidase activity. These results suggest that low concentration of Pi in the culture medium modulates ecto-3'nucleotidase activity that may lead to modulation of important processes for the cell. Interestingly, the macrophage-parasite interaction increased by 45% when L. chagasi were grown at low phosphate concentration compared to the parasites grown in the presence of high phosphate source. Altogether, the results described here suggest that 3'nucleotidase activity modulated by external stimuli, Pi concentration, could be involved on parasite-macrophage interaction.

Purine enzymes in patients with rheumatoid arthritis treated with methotrexate.

OBJECTIVES: To study (a) purine metabolism during treatment with methotrexate (MTX) in patients with rheumatoid arthritis (RA) and (b) the relation of purine metabolism with efficacy and toxicity of MTX treatment. METHODS: One hundred and three patients with active RA who started treatment with MTX were included. The initial MTX dosage was 7.5 mg/week and raised to a maximum of 25 mg weekly if necessary. The purine enzymes 5'-nucleotidase (5'NT), purine-nucleoside-phosphorylase (PNP), hypoxanthine-guanine-phosphoribosyltransferase (HGPRT), and adenosine-deaminase (ADA) were measured before the start, after six weeks, and after 48 weeks or at study withdrawal. The laboratory results were related to measures of efficacy and toxicity of MTX treatment. RESULTS: Baseline values of 5'NT and PNP (16.9 and 206.8 nmol/10(6) mononuclear cells/h, respectively) were similar to those in former studies. Activities of HGPRT and ADA were relatively low at the start (8.7 and 80.3 nmol/10(6) mononuclear cells/h, respectively). After six weeks purine enzyme activities showed no important changes from baseline. After 48 weeks of MTX treatment a decrease of the enzyme activities of ADA (-21.6 nmol/10(6) mononuclear cells/h; 95% CI -28.6 to -14.7), PNP (-78.9 nmol/10(6) mononuclear cells/h; 95% CI -109.0 to -48.7), and HGPRT (-2.0 nmol/10(6) mononuclear cells/h; 95% CI -3.1 to -0.9) was found. No association was shown between the enzyme activities of ADA, PNP, and HGPRT, and the efficacy or toxicity of MTX treatment. In contrast, enzyme activity of 5'NT showed a decrease in the subgroup of patients discontinuing MTX treatment because of hepatotoxicity. CONCLUSION: MTX treatment in patients with RA leads to a significant decrease of the purine enzyme activities of ADA, PNP, and HGPRT that is not related to the anti-inflammatory efficacy or toxicity of MTX. Hepatotoxicity was related to a decrease in the enzyme activity of 5'NT. These changes may be explained by direct or indirect (via purine de novo and salvage metabolism and the homocysteine pathway) effects of MTX.

Effects of aspirin (acetylsalicylic acid) and Cataflam (potassium diclofenac) on some biochemical parameters in rats.

The effects of graded doses of aspirin (acetylsalicylic acid) and cataflam (potassium diclofenac) on serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, 5'Nucleotidase, methaemoglobin, total and conjaged bilirubin were investigated in wistar rats. Results showed a significant increase (P < 0.05) in the levels of alanine animotransferase, aspartate amino transferase, methaemoglobin, total and conjugated bilirubin upon treatment of animals with both drugs. Aspirin significantly decreased (P < 0.05, P < 0.00) the activity of alkaline phsophatase but increased the activity of 5'ucleotidase while cataflam significantly increased the activity of alkaline phosphatase (P < 0.001) and 5'nucletodase (P < 0.05). These effects were however dose dependent and the biochemical implications of these results are discussed.

The isolation from human seminal plasma of a new form of soluble 5'-nucleotidase.

Soluble broad spectrum 5'-nucleotidase from human seminal plasma was purified to homogeneity by a combination of (NH4)2SO4 precipitation, affinity chromatography, and gel filtration. The pure enzyme had a specific activity of 4800 nmol min-1 mg-1. SDS-PAGE of purified enzyme preparation revealed a single polypeptide band of 53 kDa and a tetrameric structure of 203 kDa was proposed for the native enzyme. This form had modest preference for AMP as substrate; Mg2+ and Mn2+ were activators of the enzyme although its activity was not absolutely dependent on the presence of these exogenous bivalent cations. The enzyme, recovered in the nonsedimentable fraction of human seminal plasma, had a pH optimum of 7.5; ATP and ADP were inhibitors of mixed type, Pi was a potent inhibitor at nonphysiological concentrations, and Con A and adenosine 5-[alpha, beta-methylene]diphosphate had no effect on the enzyme activity. The enzyme described here therefore has some unique properties between truly cytoplasmic and membrane-bound derived forms.

[Danazol action on 5'-nucleotidase activity in mouse peritoneal macrophages]. / Deistvie danazola na aktivnost' 5'-nukleotidazy peritoneal'nykh makrofagov myshei.

The paper reports the results of danazol action in vivo and in vitro on 5'-nucleotidase activity of mouse peritoneal macrophages. The results showed, that danazol at a concentration of 10 M (the pharmacologic level in women taking 600 mg/day) significantly stimulated the enzyme activity.