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Species- and substrate-specific stimulation of human plasma paraoxonase 1 (PON1) activity by high chloride concentration.

100%

Bełtowski J., Wójcicka G., Marciniak A.

Acta Biochimica Polonica

2002

vol. 49

issue 4

927-936

Paraoxonase 1 (PON1), contained in plasma high-density lipoproteins, plays an important role in the protection of plasma lipoproteins and cell membranes from oxidative damage. Previous studies indicate that human PON1 is stimulated by high NaCl concentrations. The aim of this study was to characterize in more detail the effect of salts on serum PON1. Paraoxon-hydrolyzing activity of human serum was stimulated by 81.6% following the addition of 1 M NaCl. The effect of NaCl was dose-dependent between 0.5 and 2 M. PON1 activity toward phenyl acetate was reduced by 1 M NaCl by 55.2%. Both the paraoxon- and phenyl acetate-hydrolysing activity was slightly lower in heparinized plasma than in serum, but NaCl had similar stimulatory and inhibitory effects on these activities, respectively. In rat, rabbit, and mouse, NaCl reduced PON1 activity. KCl had a similar effect on human PON1 as NaCl. Sodium nitrite also stimulated human PON1 but much less effectively than chloride salts. In contrast, sucrose, sodium acetate and sodium lactate had no significant effect. NaBr was a less effective PON1 activator than NaCl, whereas the effect of NaJ was non-significant. The activity of human PON1 toward homogentisic acid lactone and γ-decanolactone was unaltered by NaCl. These data indicate that: 1) high concentrations of chlorides stimulate human PON1 activity toward paraoxon but not other substrates, 2) PON1 is inhibited by Cl- in other mammalian species, 3) the potency of human PON1 activation by halogene salts increases with decreasing atomic mass of the halide anion.

Paraoxonase-1 activities in children and adolescents with type 1 diabetes mellitus

88%

Craciun E., Leucuta D., Rusu R., David B., Cret V., Dronca E.

Acta Biochimica Polonica

2016

vol. 63

issue 3

511-515

Background: Paraoxonase-1 is an HDL-associated esterase that acts as an anti-atherogenic agent by protecting LDL from oxidation. This study investigates paraoxonase-1 activities in children and adolescents with type 1 diabetes mellitus and possible associations with other biochemical markers. Patients and methods: The study enrolled 82 children and adolescents with type 1 diabetes mellitus and 41 controls with similar age and gender distribution. Serum paraoxonase-1 arylesterase and salt-stimulated paraoxonase activities were assessed by measuring the rates of phenyl acetate and paraoxon hydrolysis, respectively; paraoxonase-1 lactonase activity and oxidized LDL were assessed by a pH-sensitive colorimetric assay and ELISA, respectively. Glycated haemoglobin HbA1c and lipid profile were assayed with an immunoturbidimetric method and commercially available kits, respectively. Results: We found lower paraoxonase-1 activities in diabetics when compared to controls. The decrease was statistically significant only for the lactonase activity, the difference being higher when referring to the subgroup with poor glycaemic control. The lactonase activity/HDL ratio was also lower in diabetics vs. controls, but without statistical significance. Both lactonase and arylesterase activities were negatively correlated with HbA1c in diabetics, but only the latter was statistically significant (ρ = -0.21, P = 0.055; ρ = -0.24, P = 0.03, respectively). A correlation coefficient of ρ = 0.196 (P = 0.078) was found between oxidized LDL and HbA1c. Conclusion: All paraoxonase-1 activities were lower in diabetic children and adolescents, but only the decrease in the lactonase activity was statistically significant. Although lipid profile and glycaemic control were altered in diabetics, no differences were observed between groups regarding oxidized LDL level.

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2 Acta Biochimica Polonica

1 2016

1 2002

1 Bełtowski J.

1 Craciun E.

1 Cret V.

1 David B.

1 Dronca E.

1 Leucuta D.

1 Marciniak A.

1 Rusu R.

1 Wójcicka G.

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Species- and substrate-specific stimulation of human plasma paraoxonase 1 (PON1) activity by high chloride concentration.

Paraoxonase-1 activities in children and adolescents with type 1 diabetes mellitus