S. Ippolito

Oxidative stress in kidney transplant patients.

Background. Little information is available about the role of oxidative stress in renal transplant patients. To evaluate the prevalence and severity of oxidative stress in renal transplantation, the authors conducted a cross-sectional study. Methods. In 112 cadaver or living-donor kidney transplant recipients with a follow-up of at least 6 months and with plasma creatinine less than or equal to 2.5 mg/dL, complete blood count, serum vitamin B12, serum folate (s-F), reactive oxygen species (ROS), thiol groups (−SH), total antioxidant activity (TAOC), serum homocysteine (Hcy), and intraerythrocyte folate (ery-F) were measured. Results. The mean levels of Hcy (21.1 &mgr;M vs. <10 &mgr;M), ROS (302.7 U. Carr (Carratelli units) vs. 250–300 U. Carr), and TAOC (410.6 &mgr;mol/HclO/mL vs. >350 &mgr;mol/HclO/mL), were higher than the reference interval, whereas −SH groups, vitamin B12, s-F, and ery-F were within the normal range. In the multivariate model, plasma creatinine (P =0.0062), vitamin B12 (P =0.0121), and TAOC (P =0.0007) were independently associated with oxidative stress. At multiple regression analysis, −SH groups and ROS were directly and inversely related to hematocrit (P =0.0007 and P =0.0073). There was also a negative correlation between −SH groups and blood pressure levels (P =0.0095). Conclusions. Renal transplant patients have a pattern of increased oxidant stress that is counterbalanced by an enhancement of the antioxidant mechanisms. Besides the well-known risk factors, the authors found that anemia is an independent risk factor for an increase of ROS. Further studies are needed to evaluate whether the correction of anemia might prevent or reduce the oxidative stress in renal transplant patients.

Free and total plasma malondialdehyde in chronic renal insufficiency and in dialysis patients

BACKGROUND Available data about oxidative status in patients with end-stage renal disease (ESRD) or on dialysis are contradictory. The present cross-sectional study aimed to investigate the role of renal insufficiency and dialysis on lipid peroxidation. To separate the effects of uraemia from dialysis-induced stress, we enrolled 26 patients with renal insufficiency on conservative treatment (ESRD), 23 on peritoneal dialysis (PD), 30 on haemodialysis (HD) and 30 controls. METHODS Plasma malondialdehyde (MDA) levels, both total (tMDA) and free (fMDA), were measured as indexes of oxidative stress by gas chromatography-mass spectrometry. Bound MDA (bMDA) levels were calculated as the difference between tMDA and fMDA. RESULTS Total and bMDA concentrations were significantly higher in patients than in controls (ESRD > HD > PD). In PD and HD patients, fMDA levels were similar and significantly higher than in ESRD. Multivariate analysis, with tMDA, fMDA and bMDA as dependent variables, showed similar and significant tMDA and bMDA relations with residual renal function (t = -2.160, P = 0.035) and albumin (t = -2.049, P = 0.045). Erythropoietin dose affected only fMDA values (t = -2.178, P = 0.034). CONCLUSIONS Free and bMDA concentrations identified different MDA patterns. Bound MDA, not excreted by kidneys, accounts alone for high tMDA concentrations in ESRD patients, while both fMDA and bMDA contribute to tMDA values in dialysis patients. These findings show that increased tMDA could be indicative not only of recent lipid peroxidation, and they also highlight the importance of evaluating free, bound and total MDA in patients with reduced renal function in order to assess their oxidative status.

Analytical performance and method comparison study of the total homocysteine fluorescence polarization immunoassay (FPIA) on the AxSYM analyzer

Abstract A fluorescence polarization immunoassay (FPIA) has been commercially released for routine large-scale testing of total homocysteine (tHcy) on the AxSYM analyzer. We evaluated the analytical performance of the AxSYM tHcy FPIA and compared it with the well established high-performance liquid chromatography (HPLC) and IMx tHcy FPIA methods. Homocysteine concentrations were measured by AxSYM and IMx tHcy FPIA and by a rapid isocratic HPLC method with fluorescence detection. Coefficient of variation (CV) of total imprecision for AxSYM tHcy was ≤5%, mean dilution recovery 102%, analytical sensitivity 0.70 μmol/l and linearity was good up to 1:8 dilution. Spearman rank correlations, rho, were 0.83 (p<0.0001) for AxSYM vs. HPLC, 0.97 (p<0.0001) for AxSYM vs. IMx and 0.83 (p <0.0001) for IMx vs. HPLC. Passing and Bablok regression Y-intercepts and slopes were: 2.944/0.937 (AxSYM vs. HPLC), −0.367/1.142 (AxSYM vs. IMx) and 2.632/0.805 (IMx vs. HPLC). Corresponding mean differences (AxSYM-Comparison Assay) recorded over a 5–50 μmol/l measured range were 1.80, −0.73 and 2.53 μmol/l. AxSYM tHcy FPIAs first rate precision, supported by the complete automation of the AxSYM analyzer, makes it fit for routine use and suitable for laboratories requiring homocysteine high-throughput testing capabilities.

Increased free malondialdehyde concentrations in smokers normalise with a mixed fruit and vegetable juice concentrate: a pilot study.

Abstract Background: Cigarette smoking, a cardiovascular risk factor leading to oxygen free radical formation, is involved in the development of serious pathological conditions. On the other hand, a healthy diet and adequate supplementation can help prevent many diseases. The aim of our study was to evaluate in healthy light smokers the effects of supplementation with mixed fruit and vegetable juice powder concentrate on homocysteine metabolism and oxidative status. Methods: In this pilot study, 32 healthy volunteers, 16 light smokers and 16 non-smokers, on twice daily supplementation were monitored at time zero and after 30days. Plasma homocysteine, and serum vitamin B12 and folate concentrations were measured by immunoenzymatic assays; reactive oxygen species, total antioxidant capacity and thiol groups by spectrophotometric methods; and total and free malondialdehyde concentrations by gas chromatography-mass spectrometry with isotopic dilution. Results: Baseline free malondialdehyde concentrations were significantly higher in smokers than in non-smokers and normalised after 30-day supplementation. Baseline results for all the other parameters remained unchanged after supplementation, with no significant differences between smokers and non-smokers. Conclusion: This is the first study showing a significant decrease in free malondialdehyde levels in light smokers after 1-month phytonutrient supplementation.

Effect of incremental doses of folate on homocysteine and metabolically related vitamin concentrations in nondiabetic patients on peritoneal dialysis

The role of folate supplementation in reducing hyperhomocystinemia in patients on dialysis has been reported, but the optimal dose of folate is still unknown. The aim of the present study was to investigate whether greater than 5 mg/day folate supplementation provides any additional effect on plasma homocysteine (HCY) levels. The study was prospective, open, and had no control group. Of the 64 eligible nondiabetic patients on peritoneal dialysis with hyperhomocystinemia (>20 &mgr;mol/L), 56 were given oral folate (5 mg/day) for 3 months. When Hcy did not fall below 20 &mgr;mol/L, folate doses were increased by 5 mg every 3 months to up to 15 mg/day. With 5 mg/day supplementation, serum folate concentrations increased above the upper confidence limit in 23 patients and erythrocyte folate concentrations in 27 patients. Hcy levels decreased to less than 15 &mgr;mol/L in 6 cases and by more than 50% in 12 cases. Nineteen of the remaining patients were given 10 mg/day folate. After increasing the dose, serum and erythrocyte folate levels rose above the upper detection limit. In one patient, plasma Hcy concentrations decreased to less than 15 &mgr;mol/L. Ten patients were given 15 mg/day oral folate for an additional 3 months with no effect on homocystinemia. This study confirms that oral folate supplementation may improve hyperhomocystinemia even in patients on dialysis with normal serum or erythrocyte folate concentrations. In fact, serum and erythrocyte levels cannot predict the effect of supplementation on plasma Hcy levels. However, 5 mg/day folate supplementation normalized Hcy in 10% of cases and reduced Hcy levels in another 21%. Increasing the folate dose to greater than 5 mg/day had a minimal (10 mg/day) or no (15 mg/day) additional effect on Hcy concentrations. Despite the minimal effect of increasing folate doses, given the low cost, the absence of side effects, and the high cardiovascular risk for patients on peritoneal dialysis, a careful attempt to increase the dose of oral folate up to 10 mg/day might be suggested.

Adrenocorticotropic hormone stability in preanalytical phase depends on temperature and proteolytic enzyme inhibitor

*Corresponding author: Marco Casati, Clinical Chemistry Laboratory , St Gerardo Hospital, via Pergolesi, 33, 20900 Monza , Italy , Phone: + 39 039 2333013, Fax: + 39 039 2333011, E-mail: m.casati@hsgerardo.org Adele Cappellani, Vittoria Perlangeli, Silvia Ippolito, Rita Romano and Lucia Carati: Clinical Chemistry Laboratory , St Gerardo Hospital, Monza , Italy Salvatore Pittalis: Clinical Pathology Laboratory , A.O. della Provincia di Lodi, Lodi , Italy Giuseppe Limonta: Clinical Pathology Laboratory , University of Milan Bicocca , Italy