Serum paraoxonase activities in hemodialyzed uremic patients: cohort study.
OBJECTIVE
To determine whether paraoxonase activity, paraoxonase phenotypes, and lipid status are altered in uremic patients on long-term hemodialysis treatment as compared to healthy population.


METHODS
Patients (n = 69) and control subjects (n = 145) were from the area of Slavonski Brod, Croatia. Paraoxon was used as a substrate for measuring basal or sodium chloride-stimulated (NaCl-stimulated) paraoxonase activity, and phenylacetate for measuring arylesterase activity. The double substrate method was used to assign phenotypes. Cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-cholesterol) were determined by methods routinely used in medical-biochemical laboratories. Enzyme activities are expressed as international units per liter of serum or per mmol of HDL-cholesterol (HDL-standardized activities).


RESULTS
Basal and NaCl-stimulated paraoxonase activity, as well as arylesterase activity expressed per serum volume, were significantly lower in the hemodialyzed uremic patients compared to the controls; 69% (p < 0.001), 73% (p < 0.001) and 49%, (p < 0.001), respectively. However, basal and NaCl-stimulated paraoxonase activity standardized for HDL-cholesterol concentrations were not significantly reduced in the hemodialyzed uremic patients as compared to controls (86%, p = 0.614 and 87%, p = 0.720, respectively), contrary to arylesterase activity, which remained significantly lower (72%, p < 0.001). The distribution of paraoxonase phenotypes in hemodialyzed uremic patients and controls was as follows: AA 45% and 39%, AB 37% and 48%, BB 18%, and 13%, respectively.


CONCLUSIONS
Patients on long-term hemodialysis have decreased paraoxonase/arylesterase activity, which might indicate a greater risk of premature atherogenesis.
Juretić
D
D
Dubravka Juretic, Division of Medical Biochemistry and Hematology, Zagreb University Faculty of Pharmacy and Biochemistry, A. Kovacica 1, 10000 Zagreb, Croatia. dubravka.juretic@fbf.tel.hr
Tadijanović
M
M
Rekić
B
B
Simeon-Rudolf
V
V
Reiner
E
E
Baricić
M
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D043303:Aryldialkylphosphatase; D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D015331:Cohort Studies; D017523:Croatia / Q000453:epidemiology; D019353:Endemic Diseases / Q000706:statistics & numerical data; D004797:Enzyme-Linked Immunosorbent Assay; D004950:Esterases / Q000097:blood* / Q000235:genetics; D005260:Female; D006801:Humans; D008055:Lipids / Q000032:analysis; D008134:Long-Term Care; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D006435:Renal Dialysis / Q000379:methods*; D018709:Statistics, Nonparametric; D014511:Uremia / Q000201:enzymology* / Q000208:ethnology / Q000628:therapy*
D015415:Biomarkers; D008055:Lipids; D004950:Esterases; D043303:Aryldialkylphosphatase