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Serum Paraoxonase Activity (serum + paraoxonase_activity)
Selected AbstractsSerum paraoxonase activity in patients with type 1 diabetes compared to healthy controlsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2002B. Mackness Abstract Background The oxidation of low-density lipoprotein (LDL) is central to current theories on the initiation and progression of atherosclerosis. Type 1 diabetes is associated with an increase in oxidative stress, which may be responsible for the increased susceptibility to coronary heart disease seen in type 1 diabetes. High-density lipoprotein (HDL) associated paraoxonase (PON1) can retard the oxidation of LDL. Design Paraoxonase activity, concentration and genotype were therefore investigated in 152 people with type 1 diabetes and 282 healthy controls. These parameters were also investigated in the group with type 1 diabetes in relation to the presence of diabetic complications. Results Both PON1 activity and concentration were significantly lower by 16·7% and 19·2% (both P < 0·05) in the type 1 diabetes group. These differences were independent of the PON1 coding region polymorphisms. The distribution of PON1 activity and mass were the same in both populations, i.e. for the PON1-192 polymorphism RR > RQ > QQ and for the PON1-55 polymorphism LL > LM > MM. There were no differences in either the PON1 polymorphisms, PON1 activity and concentration in people with type 1 diabetes in the presence or absence of micro and macro vascular complications of diabetes. Conclusions Low PON1 activity may contribute to the increased atherosclerosis found in type 1 diabetes by reducing the ability of HDL to retard LDL oxidation despite the frequently-found increased HDL in type 1 diabetes when good glycaemic control is established. [source] Serum paraoxonase activity before and after treatment of thyrotoxicosisCLINICAL ENDOCRINOLOGY, Issue 1 2004Farbod Raiszadeh Summary objective, Antioxidant effects of paraoxonase, a high density lipoprotein (HDL)-associated enzyme that inhibits low density lipoprotein cholesterol (LDL-C) oxidation in human serum, have been reported. Patients with thyroid dysfunction are more susceptible to oxidative stress, and may show enhanced LDL-C oxidation. The purpose of this study was to evaluate serum paraoxonase activity in patients with hyperthyroidism before and after treatment with methimazole (MMI). design and patients, Twenty-four hyperthyroid patients (15 women and nine men, aged 43·0 ± 12·9 years) and 23 age- and sex-matched healthy controls were studied. Serum paraoxonase activity, lipid, lipoprotein and apolipoprotein levels were measured in fasting samples. Patients were treated with MMI 20,30 mg daily for the first month, and 5,10 mg daily thereafter, and re-evaluated after 6,9 months of treatment. results, Significantly lower serum paraoxonase activity was present in hyperthyroid patients before treatment compared with the controls (43·4 ± 21·9 vs. 72·6 ± 41·2 U/ml, P < 0·005). After a mean follow-up of 7·3 months, 15 patients became euthyroid (treated) and nine were still hyperthyroid. After follow-up, serum paraoxonase activity had increased to 62·2 ± 37·4 U/ml in those who became euthyroid (P < 0·05 compared with baseline). In patients who were still hyperthyroid serum paraoxonase was unchanged from baseline, at 43·2 ± 23·2 U/ml. conclusion, Serum paraoxonase is reduced in patients with hyperthyroidism and reverts to normal after euthyroidism is attained. Reduced serum paraoxonase activity in thyrotoxicosis might predispose lipids to oxidation. [source] | ||||||||||