Paraoxonase (POND is a high-density lipoprotein (J-1D4)-associated enzyme that has been shown
to reduce the susceptibility of low-density lipoprotein (LDL) to lipid peroxidation. This study aimed to
investigate the activity and phenotype distribution of senwi PONI in uremic patients and to evaluate
the correlations of uremia-associated substances (urea, crewinine and uric acid) with PON1 activity.
This study was carried out on 50 ramie patients on maintenance hemodialysis (HD) for less than
one year (1 month — I year), and 50 uremic patients on long-term HD (5-8 years). Fifty age and sex
matched apparently healthy individuals were also recruited as a control group. Parvoxon was used as
a substrate for measuring basal or sodium chloride-stimulated (Naastimulated)paraaronase activity
and phenylacelate was used as a substratefir measuring arylesterase activity. The double substrate
method was tiled to assign phenotypes. Serum cholesterol, triglycerides, high-density lipoprotein cholesterol,
(HDL-c), low-density lipoprotein cholesterol (LDL-c), urea, creatinine and uric acid were
also determined by routine laboraiwy methods. Enzyme activities are expressed as international units
per liter of serum or per mmol of HDL-cholesterol (HDL-standardized activities), The results of the
present study revealed that basal and NaCI-stimulated paraaronase activity, as well as wylesterase
activity expressed per serum volume were significandy lower in hemodialyzed uremic patients computed
to the commis (P<0.001). However basal and NaCI-stimulated paraoxonase activity standardized
for HDL-c concentrations were not significantly reduced in the bemodialyzed airline patients as
compared to controls (P>0.05), contra°, to wylesterase activity which remained significantly lower
in patients. Pararinonase phenotype distribution was not different among the three studied groups according
to the double substrate method. Serum paratnonase activity correlated inversely with serum
urea and oratinine levels, In conclusion, the results of the present surety revealed that uremic patients
on maintenance hemodialysis have decreased paraommase/arylesterase activity which might indicate
a greater risk of premature atherogenesis. |
