Acute kidney injury in critical COVID-19 patients: usefulness of urinary biomarkers and kidney proximal tubulopathy

Tubular injury is the main cause of acute kidney injury (AKI) in critically ill COVID-19 patients. Proximal tubular dysfunction (PTD) and changes in urinary biomarkers, such as NGAL, TIMP-2, and IGFBP7 product ([TIMP-2]•[IGFBP7]), could precede AKI. We conducted a prospective cohort study from 2020/03/09 to 2020/05/03, which consecutively included all COVID-19 patients who had at least one urinalysis, to assess the incidence of PTD and AKI, and the effectiveness of PTD, NGAL, and [TIMP-2]•[IGFBP7] in AKI and persistent AKI prediction using the area under the receiver operating characteristic curves (AUCs), Kaplan-Meier methodology (log-rank tests), and Cox models. Among the 60 patients admitted to the ICU with proven COVID-19 (median age: 63-year-old (interquartile range: IQR, 55-74), 45 males (75%), median simplified acute physiology score (SAPS) II: 34 (IQR, 22-47) and median BMI: 25.7 kg/m2 (IQR, 23.3-30.8)) analyzed, PTD was diagnosed in 29 patients (48%), AKI in 33 (55%) and persistent AKI in 20 (33%). Urinary NGAL had the highest AUC for AKI prediction: 0.635 (95%CI: 0.491-0.779) and persistent AKI prediction: 0.681 (95%CI: 0.535-0.826), as compared to PTD and [TIMP-2]•[IGFBP7] (AUCs <0.6). AKI was independently associated with higher SAPSII (HR = 1.04, 95%CI: 1.01-1.06, p = 0.005) and BMI (HR = 1.07, 95%CI: 1.00-1.14, p = 0.04) and persistent AKI with higher SAPSII (HR = 1.03, 95%CI: 1.00-1.06, p = 0.048) and nephrotoxic drug use (HR = 3.88, 95%CI: 1.20-12.5, p = 0.02). In conclusion, in critically ill COVID-19 patients, the incidence of PTD and AKI was relatively high. NGAL was the best urinary biomarker for predicting AKI, but only clinical severity was independently associated with its occurrence.

Frontal Intermittent Rhythmic Delta Activity Is a Useful Diagnostic Tool of Neurotoxicity After CAR T-Cell Infusion

BACKGROUND AND OBJECTIVES

Chimeric antigen receptor (CAR) T-cell therapies have dramatically improved the prognosis of patients with relapsed or refractory hematologic malignancies; however, cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome (ICANS) occur in ∼100 and 50% of patients, respectively. This study aimed to determine whether EEG patterns may be considered as diagnostic tools for ICANS.

METHODS

Patients who received CAR T-cell therapy at Montpellier University Hospital between September 2020 and July 2021 were prospectively enrolled. Neurologic signs/symptoms and laboratory parameters were monitored daily for 14 days after CAR T-cell infusion. EEG and brain MRI were performed between day 6 and 8 after CAR T-cell infusion. EEG was performed again on the day of ICANS occurrence, if outside this time window. All collected data were compared between patients with and without ICANS.

RESULTS

Thirty-eight consecutive patients were enrolled (14 women; median age: 65 years, interquartile range: [55-74]). ICANS was observed in 17 of 38 patients (44%) after a median time of 6 days after CAR T-cell infusion (4-8). The median ICANS grade was 2 (1-3). Higher C-reactive protein peak (146 mg/L [86-256], p = 0.004) at day 4 (3-6), lower natremia (131 mmol/L [129-132], p = 0.005) at day 5 (3-6), and frontal intermittent rhythmic delta activity (FIRDA, p < 0.001) on EEG between days 6 and 8 after infusion were correlated with ICANS occurrence. FIRDA was only observed in patients with ICANS (N = 15/17, sensitivity of 88%) and disappeared after ICANS resolution, usually after steroid therapy. Except for hyponatremia, no other toxic/metabolic marker was associated with FIRDA (p = 0.002). The plasma concentration of copeptin, a surrogate marker of antidiuretic hormone secretion, assessed at day 7 after infusion, was significantly higher in patients with (N = 8) than without (N = 6) ICANS (p = 0.043).

DISCUSSION

FIRDA is a reliable diagnostic tool for ICANS, with a sensitivity of 88% and a negative predictive value of 100%. Moreover, as this EEG pattern disappeared concomitantly with ICANS resolution, FIRDA could be used to monitor neurotoxicity. Finally, our study suggests a pathogenic pathway that starts with increased C-reactive protein, followed by hyponatremia and eventually ICANS and FIRDA. More studies are required to confirm our results.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that FIRDA on spot EEG accurately distinguishes patients with ICANS compared with those without after CAR T-cell therapy for hematologic malignancy.

Analytical Performances of the Novel i-STAT Alinity Point-of-Care Analyzer

Many Point-of-Care devices have been released over the past decade. However, data regarding their analytical performances in real-world situations remains scarce. Herein, we aimed to assess the analytical performances of the i-STAT Alinity system. We conducted an analytical performances study with the i-STAT Alinity device using cartridges CG4+ (pH, Pco2, Po2, lactate, bicarbonate and base excess); CHEM8+ (Na, K, Cl, ionized Ca, urea, creatinine, glucose, hematocrit and hemoglobin) and PT/INR (prothrombin time and international normalized ratio). We assessed the imprecision and compared the results to those obtained on existing instruments in the central laboratory. We found that the within-lab coefficients of variation (CV) were very low (<2%) or low (2−5%), except for creatinine and PT (CV = 5.2% and CV = 6.3%, respectively). For almost all the parameters, the results were strongly (R2 = 90−95%) or very strongly (R2 > 95%) correlated with those of the existing laboratory instruments, and the biases were very low (<2%) or low (2−5%). However, correlations of the PT and INR measurements with existing instruments were lower (R2 = 86.0% and 89.7%), and biases in the Po2 (7.9%), creatinine (5.4%) and PT (−6.6%) measurements were higher. The i-STAT Alinity appeared as a convenient device for measurements of numerous parameters. However, clinicians should interpret Po2, creatinine and PT results with caution.

Persistence of neutrophil extracellular traps and anticardiolipin auto-antibodies in post-acute phase COVID-19 patients

In the early phase of the pandemic, we were among the first to postulate that neutrophil extracellular traps (NETs) play a key role in COVID-19 pathogenesis. This exploratory prospective study based on 279 individuals showed that plasma levels of neutrophil elastase, myeloperoxidase and circulating DNA of nuclear and mitochondrial origins in nonsevere (NS), severe (S) and postacute phase (PAP) COVID-19 patients were statistically different as compared to the levels in healthy individuals, and revealed the high diagnostic power of these NETs markers in respect to the disease severity. The diagnostic power of NE, MPO, and cir-nDNA as determined by the Area Under Receiver Operating Curves (AUROC) was 0.95, 097, and 0.64; 0.99, 1.0, and 0.82; and 0.94, 1.0, and 0.93, in NS, S, and PAP patient subgroups, respectively. In addition, a significant fraction of NS, S as well as of PAP patients exhibited aCL IgM/IgG and anti-B2GP IgM/IgG positivity. We first demonstrate persistence of these NETs markers in PAP patients and consequently of sustained innate immune response imbalance, and a prolonged low-level pro-thrombotic potential activity highlighting the need to monitor these markers in all COVID-19 PAP individuals, to investigate postacute COVID-19 pathogenesis following intensive care, and to better identify which medical resources will ensure complete patient recovery.

Neutrophil extracellular traps have auto-catabolic activity and produce mononucleosome-associated circulating DNA

BACKGROUND

As circulating DNA (cirDNA) is mainly detected as mononucleosome-associated circulating DNA (mono-N cirDNA) in blood, apoptosis has until now been considered as the main source of cirDNA. The mechanism of cirDNA release into the circulation, however, is still not fully understood. This work addresses that knowledge gap, working from the postulate that neutrophil extracellular traps (NET) may be a source of cirDNA, and by investigating whether NET may directly produce mono-N cirDNA.

METHODS

We studied (1) the in vitro kinetics of cell derived genomic high molecular weight (gHMW) DNA degradation in serum; (2) the production of extracellular DNA and NET markers such as neutrophil elastase (NE) and myeloperoxidase (MPO) by ex vivo activated neutrophils; and (3) the in vitro NET degradation in serum; for this, we exploited the synergistic analytical information provided by specifically quantifying DNA by qPCR, and used shallow WGS and capillary electrophoresis to perform fragment size analysis. We also performed an in vivo study in knockout mice, and an in vitro study of gHMW DNA degradation, to elucidate the role of NE and MPO in effecting DNA degradation and fragmentation. We then compared the NET-associated markers and fragmentation size profiles of cirDNA in plasma obtained from patients with inflammatory diseases found to be associated with NET formation and high levels of cirDNA (COVID-19, N = 28; systemic lupus erythematosus, N = 10; metastatic colorectal cancer, N = 10; and from healthy individuals, N = 114).

RESULTS

Our studies reveal that gHMW DNA degradation in serum results in the accumulation of mono-N DNA (81.3% of the remaining DNA following 24 h incubation in serum corresponded to mono-N DNA); "ex vivo" NET formation, as demonstrated by a concurrent 5-, 5-, and 35-fold increase of NE, MPO, and cell-free DNA (cfDNA) concentration in PMA-activated neutrophil culture supernatant, leads to the release of high molecular weight DNA that degrades down to mono-N in serum; NET mainly in the form of gHMW DNA generate mono-N cirDNA (2 and 41% of the remaining DNA after 2 h in serum corresponded to 1-10 kbp fragments and mono-N, respectively) independent of any cellular process when degraded in serum; NE and MPO may contribute synergistically to NET autocatabolism, resulting in a 25-fold decrease in total DNA concentration and a DNA fragment size profile similar to that observed from cirDNA following 8 h incubation with both NE and MPO; the cirDNA size profile of NE KO mice significantly differed from that of the WT, suggesting NE involvement in DNA degradation; and a significant increase in the levels of NE, MPO, and cirDNA was detected in plasma samples from lupus, COVID-19, and mCRC, showing a high correlation with these inflammatory diseases, while no correlation of NE and MPO with cirDNA was found in HI.

CONCLUSIONS

Our work describes the mechanisms by which NET and cirDNA are linked. In doing so, we demonstrate that NET are a major source of mono-N cirDNA independent of apoptosis and establish a new paradigm of the mechanisms of cirDNA release in normal and pathological conditions. We also demonstrate a link between immune response and cirDNA.

Autosomal dominant SPG9: intrafamilial variability and onset during pregnancy

INTRODUCTION

The ALDH18A1 gene, encoding delta-1-pyrroline-5-carboxylate synthase (P5CS), is responsible for an autosomal recessive disease with severe developmental delay; more recently, ALDH18A1 was found to be responsible for SPG9, an autosomal dominant (AD) spastic paraplegia.

CASE REPORT

We report a three-generation family with AD SPG9, initially suspected because of low citrulline on fasting plasma amino acid chromatography (AAC). Interestingly, in two patients, the spastic paraplegia appeared during pregnancy. One subject presented a severe childhood-onset form while another subject had a mild late-onset disease.

CONCLUSION

The description of this family is of particular interest: it highlights the possibility of transient or permanent aggravation of spastic paraplegia due to SPG9 during pregnancy, suggesting a direct link between neurological symptoms and amino acid defect in a period of higher requirements and the potential benefit of amino acid supplementation; it underscores the value of plasma citrulline on fasting plasma AAC as a biomarker for this disease; it shows the variable expression of the disease.

Improved quality of samples and laboratory turnaround time using 3.5 mL low vacuum BD Vacutainer® Barricor tubes in the emergency department

Background

Centrifugation is a consuming time step which participates to increase the turnaround time (TAT) in laboratories, likewise hemolysis sample that needs a re-sampling could delay management of patients. Recently, it has been postulated that BD Barricor™ tube could allow to decrease the centrifugation time and prevent hemolysis, two key feature to ensure high-quality results.

Aim of the study was to evaluate the impact of replacing 4 mL BD vacutainer heparin lithium tube by low vacuum 3.5 mL BD vacutainer Barricor™ tube in an emergency department (ED) on hemolysis rate and TAT.

Methods

Data of hemolysis index (HI) and TAT were compared between the first period of 15 days using 4 mL BD vacutainer heparin lithium tubes with 15 min at 2000xg as centrifugation setting and a second period of 15 days using BD vacutainer Barricor™ tube centrifuged 3 min at 4000xg.

Results

A significantly reduced time duration between reception of sample and available results in informatics lab system was observed with the reduction time of centrifugation allowed by use of Barricor™ tube compared to regular heparin lithium tubes (p < 0.001). A significative decrease in hemolysis rate also occurred in the second period as samples with HI < 10 reached from 52.5% in the first period to 68.5% (p < 0.001) in the second.

Conclusion

Low vacuum Barricor^TM tubes allowing a higher speed of centrifugation improve lab TAT without impairment of sample quality as a significant reduction of hemolysis was observed, a double advantage which is of particular interest for ED.

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Improving turnaround time and quality samples is a challenge for all laboratories.

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Hemolyzed samples occurrence is higher in the emergency department.

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Low vacuum tube can reduce the hemolysis rate of blood sampling.

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Higher speed centrifugation could reduce centrifugation time and turnaround time.

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Low vacuum Barricor tube in emergency unit improve hemolysis rate and turnaround time.

Fine-scale haplotype mapping of MUT, AACS, SLC6A15 and PRKCA genes indicates association with insulin resistance of metabolic syndrome and relationship with branched chain amino acid metabolism or regulation

Branched chain amino acids (BCAA) are essential elements of the human diet, which display increased plasma levels in obesity and regained particular interest as potential biomarkers for development of diabetes. To define determinants of insulin resistance (IR) we investigated 73 genes involved in BCAA metabolism or regulation by fine-scale haplotype mapping in two European populations with metabolic syndrome. French and Romanians (n = 465) were genotyped for SNPs (Affymetrix) and enriched by imputation (BEAGLE 4.1) at 1000 genome project density. Initial association hits detected by sliding window were refined (HAPLOVIEW 3.1 and PHASE 2.1) and correlated to homeostasis model assessment (HOMAIR) index, in vivo insulin sensitivity (SI) and BCAA plasma levels (ANOVA). Four genomic regions were associated with IR located downstream of MUT, AACS, SLC6A15 and PRKCA genes (P between 9.3 and 3.7 x 10-5). Inferred haplotypes up to 13 SNPs length were associated with IR (e.g. MUT gene with P < 4.9 x 10-5; Bonferroni 1.3 x 10-3) and synergistic to HOMAIR. SNPs in the same regions were also associated with one order of magnitude lower P values (e.g. rs20167284 in the MUT gene with P < 1.27 x 10-4) and replicated in Mediterranean samples (n = 832). In French, influential haplotypes (OR > 2.0) were correlated with in vivo insulin sensitivity (1/SI) except for SLC6A15 gene. Association of these genes with BCAA levels was variable, but influential haplotypes confirmed implication of MUT from BCAA metabolism as well as a role of regulatory genes (AACS and PRKCA) and suggested potential changes in transcriptional activity. These data drive attention towards new regulatory regions involved in IR in relation with BCAA and show the ability of haplotypes in phased DNA to detect signals complimentary to SNPs, which may be useful in designing genetic markers for clinical applications in ethnic populations.

Point of Care Cardiac Troponin Assay Analytical Performances for their Use in Clinical Routine

BACKGROUND

We report the analytical and clinical performances of the Alere Triage Cardiac3© Panel on the Triage MeterPro© instrument, comparing concordance with hs-cTnT results from central laboratory above the respective 99th percentiles and determining the clinical sensitivity within the framework of AMI.

METHODS

The concordance was obtained with these two methods among unselected patients admitted to both the emergency and cardiology departments.

RESULTS

The LoD of the assay is 0.010 µg/L. At 99th percentile (0.02 µg/L) the CV was found to be 18%, below the clinically acceptable cutoff of 20%. In the overall population, ROC AUC was not significantly different between the central laboratory assay and POC assay, with 0.952 (95% CI, 0.918 - 0.952) for hs-cTnT concentrations at presentation and 0.953 (95% CI, 0.912 - 0.953) for cTnI. Sensitivity and specificity of hs-cTnT vs. cTnI for AMI (n = 32) were 97% and 78% vs. 91% and 86%, respectively. Our results indicated 90.4% concordance between the two methods using the 99th percentile specific for each assay. The Kappa coefficient was higher than 0.75, and the strength of agreement could be considered to be good.

CONCLUSIONS

The results of cTnI Alere assays provide similar clinical classification of patients, particularly for the AMI group as compared to the central laboratory hs-cTnT assay and could be suitable for clinical in accordance with the recommendations of Global Task Force guidelines.

Association between breast milk fatty acids and HIV-1 transmission through breastfeeding

A residual mother-to-child transmission of HIV through breastfeeding persists despite prophylaxis. We identified breast milk fatty acids (FA) associated with postnatal HIV transmission through breastfeeding in a case-control study. Cases (n=23) were HIV-infected women with an infant who acquired HIV after 6 weeks of age. Controls (n=23) were matched on infant׳s age at sample collection. Adjusting for maternal antenatal plasma CD4 T cell count, cis-vaccenic acid (18:1n-7) and eicosatrienoic acid (20:3n-3) were associated with HIV transmission in opposite dose-response manner: OR (tertile 3 versus tertile 1): 10.8 and 0.16, p for trend=0.02 and 0.03, respectively. These fatty acids correlated with HIV RNA load, T helper-1 related cytokines, IL15, IP10, and β2 microglobulin, positively for cis-vaccenic acid, negatively for eicosatrienoic acid. These results suggested a change in FA synthesis by mammary gland cells leading to increased cis-vaccenic acid in milk of mothers who transmitted HIV to their infant during breastfeeding.

Long term reference change value of creatinine in HIV-positive patients with anti-retroviral therapy: A new tool in clinical practice

BACKGROUND

The use of reference change value (RCV) instead of reference interval emerged as an alternative approach for longitudinal interpretation of biological marker. Follow-up of creatinine variation in HIV-positive adults remains a challenge in order to prevent renal complications.

OBJECTIVES

To determine the long term RCV of creatinine in HIV-positive adults receiving anti-retroviral therapy (ART) according to the use of tenofovir or ritonavir.

DESIGN AND METHODS

Longitudinal study of 24 months that include 124 HIV-positive patients followed in HIV outpatient unit. Plasma creatinine was measured at 0, 6, 12 and 24 months in order to calculate the RCV.

RESULTS

In the whole group, a 24-month RCV of creatinine was 22.5%. Whatever the ART, the index of individuality was <0.6. Significantly higher RCV of creatinine was observed in patients receiving the association tenofovir and ritonavir (28%) compared to the patients receiving i) tenofovir without ritonavir (21.9%), ii) no tenofovir but ritonavir (22.2%), and iii) no tenofovir and no ritonavir (19.7%).

CONCLUSIONS

The low value of index of individuality pinpointed that RCV should be used to identify critical change in serial creatinine results in HIV-positive adults. RCV of creatinine under ART was around 20% but reached 28% in case of association of tenofovir and ritonavir.

Homocysteine as a determinant of left ventricular ejection fraction in patients with diabetes

BACKGROUND

A link between homocysteine (Hcy) and left ventricular ejection fraction (LVEF) emerged from recent studies but was yet not explored specifically in diabetic patients. This study aimed to assess the relationship between LVEF and Hcy in a cohort of adults with diabetes.

METHODS

LVEF was determined through the measure of left ventricular end-diastolic/end-systolic volumes in 409 consecutive asymptomatic patients with diabetes who underwent stress myocardial perfusion imaging. Clinical and biological parameters which were determinants of LVEF in univariate analyses with p<0.15 were included in a multivariate analysis.

RESULTS

In univariate analyses, factors significantly associated with a LVEF<55% were gender [women vs. men, odds ratio (OR)=0.22 (0.13; 0.38)], peripheral arterial disease [OR=2.49 (1.34; 4.62)], active smoking [OR=1.97 (1.16; 3.33)], silent myocardial ischemia (SMI) [OR=2.19 (1.25; 3.86)], the highest vs. the lowest tertile of creatinine [OR=2.08 (1.17; 3.68)], of albuminuria [OR=2.22 (1.27; 3.90)] and of Hcy [OR=1.83 (1.07; 3.13)]. No relationship was observed between blood pressure and decrease in LVEF. In the multivariate analysis, female gender was confirmed as being protective for having a LVEF<55%. Presence of SMI [OR=2.20 (1.14; 4.23)] and Hcy ≥15 μmol/L [OR=1.81 (1.06; 3.07)] were the two remaining significant factors associated with an increased relative risk of having LVEF<55%. A trend was only observed for the criteria active smokers.

CONCLUSIONS

This study highlights an inverse relationship between Hcy and LVEF in patients with diabetes, independent of age, gender, SMI, smoking, blood pressure, renal function, folates, vitamin B12, lipid parameters and hepatic enzymes.

Accuracy of GFR predictive equations in renal transplantation: validation of a new turbidimetric cystatin C assay on Architect c8000

OBJECTIVES

To evaluate the Sentinel-PETIA cystatin C on Architect c8000 analyzer.

DESIGN AND METHODS

We assessed analytical performances and clinical relevance by comparison with a reference isotopic method in kidney transplant recipients.

RESULTS

This assay exhibited reliable precision and was close to the non standardized Siemens-PENIA method. All tested equations allowed reliable assessment of GFR.

CONCLUSIONS

Cystatin C improved GFR determination at the critical level of 60 mL/min/1.73 m². New formulas might be necessary after IFCC standardization.

Determinants of homocysteine levels in Ivorian rural population

In the present study, homocysteine (Hcy) and vitamin B status were determined in healthy subjects living in two opposite regions of the Ivory Coast. Fifty-six subjects from a coastal region (Bodou) having a fish-based diet and 56 subjects from a mountainous area (Glanle) having a vegetarian diet were tested to sample Hcy, folate, vitamin B12, creatinine, and lipid levels, as well as inflammation and nutritional parameters. An increased prevalence of Hcy > or = 15 micromol/L was observed, reaching 60 % of all subjects. The Bodou group exhibited significantly higher Hcy levels than the Glanle group [20.1 (9.7 - 41.4) vs. 13.6 (5.5 - 48.7) micromol/L, p<0.0001], despite higher vitamin B12 levels [593 (163 - 1860) vs. 234 (83 - 585) pg/mL, p<0.0001]. Although folate levels were lower in subjects from Bodou compared to Glanle [3.2 (2.0 - 7.3) vs. 6.0 (1.9 - 18.2) ng/mL, p<0.0001], there was no significant relationship with Hcy levels in any groups. Interestingly, there were significantly higher creatinine levels in subjects from Bodou compared to Glanle and a significant positive relationship with Hcy levels was evident in each group. In conclusion, Hcy levels in an Ivorian population having a fish-based diet appeared significantly higher compared to subjects having a vegetarian diet. However, folate and vitamin B12 status did not emerge as the major determinants of this difference; a stronger relationship was observed with creatinine levels.

Evolution of coronary artery calcifications following kidney transplantation: relationship with osteoprotegerin levels

We prospectively assessed the evolution of coronary artery calcification (CAC) and osteoprotegerin (OPG) levels after renal transplantation (RT). Eighty-three recipients were followed-up prospectively during 1 year. Blood was collected before (baseline) and after RT for determination of mineral metabolism parameters including OPG. CAC was measured by multidetector computed tomography at transplantation (baseline) and 1 year later. Progression of CAC was defined as a difference between the follow-up square-root transformed volume (SRV) and the baseline SRV >or= 2.5. By multivariate analysis, baseline OPG level, age and low LDL levels were significantly associated with baseline CAC. RT was accompanied by mineral metabolism improvement with a decrease of OPG from 955 [395-5652] to 527 [217-1818] pg/mL and parathyroid hormone from 94 [1-550] to 62 [16-410] pg/mL. Thirty-one percent of patients did not exhibit CAC at baseline. CAC diminished in 14.5%, stabilized in 59.2% and progressed in 26.3% of patients. Baseline CAC was associated with progression (OR 2.92 [1.02-8.36]). No significant association was found between OPG and CAC progression despite a higher baseline OPG level in progressors (1046 [456-3285]) vs. non-progressors (899 [396-5952] pg/mL). CAC at baseline, but not 1 year after RT, is independently associated with baseline OPG; posttransplant CAC progression is predicted by baseline CAC score.

A multicenter assessment of the analytical performance of the routine thyroid panel on the Olympus AU3000i immunoassay system

BACKGROUND

The AU3000i thyroid assay panel (TSH, fT4, T4, fT3, T3) was evaluated at four sites in a European multicenter study. The study was designed to assess the basic analytical performance characteristics of the Olympus thyroid assays. In addition, a comprehensive assessment of the TSH functional sensitivity was undertaken to challenge the manufacturer's claim of 4th generation assay performance.

RESULTS

Repeatability (within-run precision) of TSH, ff4 and T4 was better than 3% across the measurable range, T3 and fT3 repeatability was better than 6%. Within-laboratory (total) precision was better than 10% for all assays, for fT4, it was better than 3%. Method comparisons were undertaken against the Roche Elecsys 2010, the Siemens Advia Centaur and the Abbott Architect. Overall, good to excellent correlations were seen, however in some cases there were systematic differences which can be attributed to the lack of an appropriate standard or reference method and/or heterogeneity of the analyte. The functional sensitivity of the Olympus TSH assay was confirmed to be 4th generation, giving a mean functional sensitivity (at 20% CV) of 0.0011 mIU/L with no sites exceeding 0.002 mIU/L. Plasma (Li-heparinate) was shown to be an acceptable sample type for use in these assays.

CONCLUSION

The results generated in this study indicate that the assays of the Olympus AU3000i routine thyroid panel are precise, correlate well with other established assays, and are suitable for use in the routine clinical laboratory.

Multicenter evaluation of workflow performances of the new Olympus AU3000i

BACKGROUND

A new immunoanalyzer (AU3000i) has been developed by Olympus (Rungis, France) with the intention of offering a consolidated workcell. The aim of this experiment was to assess, in a multi-centre study (two French sites, one German site), the practicability of the Olympus AU3000i in terms of throughput (test/h), rerun capabilities, emergency sample handling and reflex test capabilities.

RESULTS

The workload study showed that the AU3000i was capable of running both one- and two-step assay protocols with a throughput of 240 tests per hour which corresponds to 209.3 tests per hour including the initialization time. Emergency samples were correctly treated as a priority in less than 30 minutes for ten samples. Furthermore the analyzer could be programmed to generate automatic dilution, rerun and reflex tests, reducing the hands-on labour time for technicians.

CONCLUSION

Workflow studies showed that Olympus AU3000i and AU Clinical Chemistry can cover the combined workload of various routine analyzers in a variety of laboratory environments.

A New DiaSys colorimetric assay for plasma homocysteine: application in diabetic patients

This study was conducted to evaluate the analytical performance of a new colorimetric assay for plasma homocysteine (Hcy) and to determine the influence of the method used on the frequency of hyperhomocysteinemia and on the association between Hcy and biological parameters in diabetic patients. Plasma Hcy was measured in 160 diabetic patients by high performance liquid chromatography (HPLC) in parallel with an automated colorimetric assay (DiaSys Diagnostic Systems GmbH) using the Olympus AU640 and Abbott C8000 analyzers. Plasma glucose, creatinine, folates, vitamin B(12), high-sensitivity C-reactive protein (hs-CRP), and blood hemoglobin A1c (HbA1c) concentrations were measured by routine methods. The Hcy concentrations obtained with the HPLC (x) and colorimetric methods (y) were highly correlated (y = 1.032x - 0.65, r(2) = 0.884 for AU640; y = 1.028x + 0.87, r(2) = 0.934 for C8000). The frequency of Hcy >15 micromol/L was 41.9% by HPLC assay and there was no statistically significant difference using the colorimetric method. Patients with Hcy >15 micromol/L compared to < or =15 micromol/L using HPLC had significantly lower glycemia (p <0.001), lower HbA1c (p <0.001), lower estimated glomerular filtration rate (GFR) (p <0.0001), and lower vitamin B(12) levels (p <0.001). All these relationships were also noted when using the colorimetric assay on the Olympus AU640 or Abbott C8000 analyzers. In summary, this study shows that the DiaSys colorimetric assay is suitable for plasma Hcy determinations in routine clinical biochemistry.

Association of non-HDL cholesterol with subclinical atherosclerosis in HIV-positive patients

OBJECTIVES

To assess the relationship between non-classical cardiovascular (CV) risk factors including non-HDL cholesterol (non-HDL-C), apolipoprotein B, triglycerides to HDL ratio, LDL size, inflammation or oxidative stress parameters and carotid intima-media thickness (CIMT), in order to better identify prevention or therapeutic targets. In addition, we studied the relationship between metabolic syndrome (MS) and CIMT.

METHODS

Cross-sectional study including 232 HIV-positive (HIV+) adults (80% treated by combined antiretroviral therapy) extracted from the ANRS CO3 Aquitaine Cohort.

RESULTS

There was a significant association of higher non-HDL-C (p<0.01), apolipoprotein B (p<0.01) levels or TG/HDL ratio (p<0.05) with higher CIMT when compared the first vs fourth quartile, while there is no association between CIMT and LDL-C (p=0.09) or LDL size (p=0.55). In multivariate analysis, only the TG/HDL molar ratio > 1.5 tend toward significance (p=0.08). MS was observed in only 7.3% of patients with the NCEP-ATP III definition and 11.2% with the IDF criteria. Whatever the used definition, there was a significant association between MS presence and increased CIMT (p<0.05) in univariate and multivariate model.

CONCLUSIONS

Non-HDL-C, TG/HDL ratio and apolipoprotein B levels, which are closely linked to lipid disorders associated to the MS, appear as stronger predictive markers than LDL-C for screening subclinical atherosclerosis in HIV+ populations. Achieving non-HDL-C target defined by the NCEP-ATP III guidelines appears of great importance to reduce CV complications in HIV+ patients.

Physical activity modulates heat shock protein-72 expression and limits oxidative damage accumulation in a healthy elderly population aged 60 90 years

BACKGROUND

Reactive oxygen species production increases during aging, whereas protective mechanisms such as heat shock proteins (HSPs) or antioxidant capacity are depressed. Physical activity has been hypothesized to provide protection against oxidative damage during aging, but results remain controversial. This study aimed to investigate the effect of different levels of physical activity during aging on Hsp72 expression and systemic oxidative stress at rest and in response to maximal exercise.

METHODS

Plasma antioxidant capacity (Trolox equivalent antioxidant capacity, TEAC), thiobarbituric acid-reactive species (TBARS), advanced oxidized proteins products (AOPP), and Hsp72 expression in leukocytes were measured before and after maximal exercise testing in 32 elderly persons (aged 73.2 years), who were assigned to two different groups depending on their level of physical activity during the past 12 months (OLow = moderate to low level; OHigh = higher level).

RESULTS

The OHigh group showed higher aerobic fitness and TEAC (both representing 120% of OLow values) as well as lower oxidative damage (50% of OLow values) and Hsp72 expression. Exercise led to a lower increase in oxidative damage in the OHigh group. Aerobic fitness was positively correlated with TEAC and negatively with lipid peroxidation (TBARS). Hsp72 expression was negatively correlated with TEAC but positively correlated with TBARS levels.

CONCLUSIONS

The key finding of this study is that, in people aged 60 to 90 years, long-term high level of physical activity preserved antioxidant capacity and limited oxidative damage accumulation. It also downregulated Hsp72 expression, an adaptation potentially resulting from lower levels of oxidative damage.

Adaptation and evaluation of the Randox full-range CRP assay on the Olympus AU2700

The implementation of a high-sensitivity CRP (hs-CRP) assay as a routine laboratory parameter may be necessary. A single CRP method that could yield reliable results for the whole concentration range (0.1-200 mg/L) would be the most practical solution for the laboratory setting. The aim of this study was to assess the Randox full-range CRP assay on the Olympus AU2700 biochemistry analyzer and evaluate its analytical performance on serum and heparin plasma samples. The Randox CRP turbidimetric assay was compared with the existing CRP assay used routinely on the Olympus AU2700. The analytical performance of the Randox CRP with both Olympus CRP reagents (CRP for normal application and hs-CRP) was good. We found that the Randox CRP method in the range of 0.5-160 mg/L was closely correlated to the Olympus CRP and hs-CRP for serum samples. According to a Bland-Altman analysis, the serum and heparinized samples showed an excellent agreement in CRP concentrations throughout the entire range (mean difference = -0.035 +/- 1.806 mg/L) as well as in CRP levels <10 mg/L. Our data indicate that Randox full-range CRP measurements using an immunoturbidimetry assay on Olympus systems perform as well for routine diagnostics as other high-sensitivity applications using serum or heparin plasma.

Small dense low-density lipoprotein in renal transplant recipients: a potential target for prevention of cardiovascular complications?

BACKGROUND

Immunosuppressive therapy is frequently associated with dyslipidemia, which is involved in cardiovascular morbidity and mortality in transplant patients. Beyond classical factors, such as low-density lipoprotein (LDL) cholesterol (LDL-C), qualitative abnormalities of lipoproteins, such as presence of the atherogenic factor, small dense LDL, may be of interest for a cardiovascular risk assessment. This study was designed to explore LDL size in renal transplant recipients in relation to quantitative lipid parameters and apolipoprotein (apo) CIII polymorphism.

METHODS

Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), LDL-C, apoA1, apoB, apoCIII, and LDL size were measured in 62 patients of mean age 45 +/- 13 years including 71% men at 2 +/- 0.5 years after renal transplantation. Thirty-two patients received cyclosporine (CsA), while 30 received tacrolimus (FK). ApoCIII Sstl genotype was determined by restriction fragment length polymorphism.

RESULTS

The CsA group exhibited higher TC (P = .001), LDL-C (P = .004), non-HDL-C (P = .009), HDL-C (P = .03), apoB (P = .008), and apoCIII (P = .002) levels than the FK group. However, LDL-C (CsA: 3.7 +/- 1.2, FK: 3.0 +/- 0.6 mmol/L) and triglyceride levels (CsA: 1.55 mmol/L, FK: 1.37 mmol/L) were near the normal range in both groups. Allelic frequency of the sparse A2 allele associated with hypertriglyceridemia was 6%, similar to the general population. LDL size, which was comparable in the CsA and FK groups (25.87 +/- 0.89 vs 25.75 +/- 0.62 nm, respectively), inversely correlated with TG/HDL ratio (P = 10(-4)). Prevalence of small dense LDL (defined as <25.5 nm) was 26% in the CsA group and 33% in the FK group.

CONCLUSION

After LDL-C goal has been achieved, LDL size modulation may be taken into account in order to prevent cardiovascular complications.

High Prevalence of Small Dense LDL as an Underestimated Component of Heart Transplantation–Induced Dyslipidemia: Potential Role in Graft Coronary Vasculopathy?

Heart transplantation-induced dyslipidemia is a recognized risk factor for cardiac allograft vasculopathy that affects survival prognosis. Beyond increased lipids, low-density lipoprotein (LDL) size and systemic factors, including glucose intolerance, oxidative stress, and inflammation, must be taken into account as components of the atherosclerotic risk. The aim of this study was to explore the atherogenic profile of heart transplant recipients (HTR) by assessing lipid parameters, glycemia, oxidative stress status, and inflammation in 59 transplant patients (follow-up of 6 +/- 3 years) compared to 20 healthy volunteers. Classical hypercholesterolemia and hypertriglyceridemia were observed in HTR compared to controls, associated with increased apoCIII levels (0.13 +/- 0.6 vs 0.07 +/- 0.03 g/L, P < .01). Mean LDL size was reduced in HTR compared to controls (25.22 +/- 0.72 vs 26.06 +/- 0.54 nm, P < .001) with an abnormally high prevalence (69% vs 0%, P < .001) of small dense LDL (<25.5 nm). Hyperglycemia (7.3 +/- 3 vs 5.4 +/- 0.8 mmol/L, P < .05) and inflammation (high-sensitive CRP: 3.1 +/- 3 vs 1.6 +/- 0.9 mg/L, P < .001) were evidenced in HTR since no difference in oxidative stress parameters was observed. In conclusion, a high prevalence of small dense LDL is an important component of posttransplantation dyslipidemia.

Circulating leptin concentrations can be used as a surrogate marker of fat mass in acute spinal cord injury patients

To determine the acute effect of neurological lesion on body composition, plasma leptin level, and the lipid profile, 7 male patients with acute and complete spinal cord injury (SCI) and 9 able-bodied (AB) males were investigated. At 16, 24, 36, and 48 weeks after injury, plasma leptin level and the lipid profile were analyzed, while whole body (WB) and regional fat mass (FM) and fat-free soft tissue (FFST) were measured by dual-energy x-ray absorptiometry (DXA). At all stages, despite no difference being found between both groups for body mass index (BMI), SCI patients had higher FM at WB (P < .01), lower (P < .01), and upper limbs (P < .05), while FFST was lower at WB (P < .05) and lower limbs (P < .01). The leptin level increased gradually from week 24 and was higher at weeks 16, 36, and 48 in SCI patients than in AB patients (7.0 +/- 3.9; 9.7 +/- 5.1; 10.6 +/- 5.3, respectively, v 3.5 +/- 2.5 ng. mL(-1)). SCI patients had lower high-density lipoprotein-cholesterol (HDL-C) (P < .05) and apolipoprotein (apo) A1 (P < .01), while no difference was found for total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), or ApoB levels. At all stages, leptin was strongly and positively correlated with WB and regional FM % (r > 0.75; P < .05) and with TC, LDL-C, and ApoB levels (r > 0.65; P < .05). Leptin was negatively correlated with FFST and the ApoA1/ApoB ratio (r > -0.75; P < .05). In conclusion, neurological lesion induced an early and acute alteration in body composition and lipid profile. The strong relationship between serum leptin and FM suggests that this hormone can be used as a surrogate marker of FM in acute SCI patients and thus would serve as a good indicator for cardiovascular disease risk.

Comparison between the enzymatic vitros assay for creatinine determination and three other methods adapted on the Olympus analyzer

To evaluate the relationship between the enzymatic Vitros assay for creatinine determination and other methods, we determined creatinine concentration in 400 heparin samples. Plasma creatinine level was successively determined on the Vitros 750 analyzer (Johnson & Johnson Co., Rochester, NY) and on the Olympus AU2700 analyzer (Olympus France, Rungis, France), using three reagents in the same assay: Olympus-Jaffé and two enzymatic commercial kits-Crea Plus (Roche Diagnostics, Meylan, France) and Enzymatic Creatinine (Randox, Mauguio, France). Comparison of Jaffé and enzymatic measurements of plasma creatinine levels revealed a high correlation when considering all values ranged from 20-1000 micromol/l (r > 0.99). However, for values <60 micromol/l, enzymatic reagents provided best results. Enzymatic methodology is a better clinical choice for the accurate measurement of creatinine, especially for neonates, pediatrics, and hematology units. Because analytical performance and the costs of Randox creatinine were satisfactory for our laboratory, this method, adapted on the Olympus analyzer, was chosen for routine determination of creatinine levels. According to the Valtec protocol (8), no interferences such as hemolysis, lipemia, or bilirubin were detected for Enzymatic Creatinine Randox.

Fenofibrate improves the atherogenic lipid profile and enhances LDL resistance to oxidation in HIV-positive adults

BACKGROUND

Low HDL-cholesterol, hypertriglyceridemia (HTG) and occurrence of small dense LDL could be involved in increased cardiovascular risk in HIV-infected patients. This study evaluates the effects of fenofibrate and/or Vitamin E on lipoprotein profile.

DESIGN

Thirty-six HIV-positive adults with fasting triglycerides (TGs) > or =2 mmol/l and stable antiretroviral therapy (ART) were randomly assigned to receive either micronised fenofibrate (200 mg/day) or Vitamin E (500 mg/day) for a first period of 3 months and the association of both for an additional 3-month period.

METHODS AND RESULTS

Total cholesterol, HDL-C, LDL-C, triglycerides, apoA1, apoB, apoCIII, lipoprotein composition, LDL size and LDL resistance to copper-induced oxidation were determined before initiation of fenofibrate or Vitamin E, and 3 and 6 months thereafter. Three months of fenofibrate treatment results in a significant decrease in triglycerides (-40%), apoCIII (-21%), total cholesterol (-14%), apoB (-17%) levels, non-HDL-C (-17%), TG/apoA1 ratio in HDL (-27%) associated with an increase in HDL-C (+15%) and apoA1 (+11%) levels. Moreover, fenofibrate increases LDL size and enhances LDL resistance to oxidation. Three months of Vitamin E supplementation only improves LDL resistance to oxidation and addition to fenofibrate results in a slightly greater effect.

CONCLUSION

Fenofibrate therapy improves the atherogenic lipid profile in HIV-positive adults with hypertriglyceridemia.

Determination of plasma amino acids by fluorescent derivatization and reversed-phase liquid chromatographic separation

Amino acid analysis in physiological fluids remains expensive, as it usually requires a dedicated analyzer. We modified an RP-HPLC method originally devoted to peptide and protein hydrolysate analysis in order to apply it to plasma amino acid determination. The described method uses a commercial kit based on 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate derivatization followed by reversed-phase high-performance liquid chromatography. The described method is easy to use and allows the determination of twelve amino acids frequently involved in aminoacidopathies, thus enabling the diagnosis and follow-up of affected patients. The results obtained by this method are comparable to those obtained with a classical amino acid analyzer.

Vitamin E supplementation increases LDL resistance to ex vivo oxidation in hemodialysis patients

BACKGROUND

Oxidative stress and alterations in lipid metabolism observed in hemodialysis patients potentiate the low-density lipoprotein (LDL) oxidability, recognized as a key event during early atherogenesis.

OBJECTIVE

To explore the effects of an oral vitamin E supplementation on oxidative stress markers and LDL oxidability in hemodialysis patients.

METHODS

Fourteen hemodialysis patients and six healthy volunteers were given oral vitamin E (500 mg/day) for six months. Oxidative stress was assessed using: plasma and lipoprotein vitamin E levels [high-performance liquid chromatography (HPLC) procedure]; thiobarbituric acid reactive substances (TBARS, Yaggi method); and copper-induced LDL oxidation. All parameters were evaluated before initiation of vitamin E supplementation, and at three and six months thereafter.

RESULTS

At baseline, a significantly higher TBARS concentration and a higher LDL oxidability were observed in hemodialysis patients when compared to controls. After six months of vitamin E supplementation, TBARS and LDL oxidability were normalized in hemodialysis patients.

CONCLUSION

Our data confirm that hemodialysis patients are exposed to oxidative stress and increased susceptibility to ex vivo LDL oxidation. Since oral vitamin E supplementation prevents oxidative stress and significantly increases LDL resistance to ex vivo oxidation, supplementation by natural antioxidants such as vitamin E may be beneficial in hemodialysis patients.

Decrease in LDL size in HIV-positive adults before and after lopinavir/ritonavir-containing regimen: an index of atherogenicity?

BACKGROUND

Hypertriglyceridemia (HTG) is frequently observed during highly active antiretroviral therapy (HAART) including protease inhibitor. Apolipoprotein (apo) CIII could be involved in this HTG by inhibition of triglyceride (TG) hydrolysis, which leads to the occurrence of small dense low density lipoprotein (sdLDL), a recognized cardiovascular risk factor.

OBJECTIVE

To characterize the influence of lopinavir/ritonavir-containing regimen on lipoprotein profile.

DESIGN AND METHODS

24 antiretroviral-experienced HIV infected adults (including 14 patients in therapeutic interruption of at least 2 months) and 14 HIV uninfected healthy controls were enrolled. Serum lipid parameters (total cholesterol (TC), HDL-C, LDL-C, TG, apoA1, apoB, apoCIII), lipoprotein composition and LDL size were determined before initiation of lopinavir/ritonavir-containing regimen, and at 1 and 3 months thereafter.

RESULTS

At baseline an atherogenic lipid profile was evidenced, characterized by a moderate HTG associated to a smaller mean LDL size (25.16 vs 25.93 nm, P<0.001), an enrichment in TG of LDL (11.4 vs 6.0%, P<0.01) and a high prevalence of sdLDL (75 vs 7%, P<0.01) when compared to controls. After 1 month of lopinavir/ritonavir-containing regimen, a significant reduction of LDL size (24.81 vs 25.16 nm, P<0.05) and a significant increase in cholesterol total (5.53 vs 4.49 mmol/l, P<0.001), in TG (4.20 vs 2.01 mmol/l, P<0.001), in apoA1 (1.28 vs 1.11 g/l, P<0.001), in apoB (1.08 vs 0.94 g/l, P<0.01), in apoCIII (0.16 vs 0.10 g/l, P<0.001), in TG percentage in LDL (14.4 vs 11.4, P<0.05) and in TG percentage in HDL (10.2 vs 8.3, P<0.05) were observed.

CONCLUSIONS

Advanced stage of HIV infection is associated with an atherogenic lipid profile including a high prevalence of sdLDL. Lopinavir/ritonavir-containing regimen accentuates the reduction of LDL size. Since fibrates decrease TG and increase LDL size, they appear as a logical option to manage HAART-induced HTG.

The relationship between apolipoprotein E4 and lipid metabolism is impaired in Alzheimer's disease

BACKGROUND

Human apolipoprotein (Apo) E4 (ApoE4) is an important determinant of lipid metabolism and cell-to-cell cholesterol transport. It is also a major genetic risk factor for both vascular disease and familial and sporadic late-onset Alzheimer's disease (AD). Since vascular pathology could dramatically reduce neuronal reserve capacity, a biological chain of events between ApoE4, hypercholesterolemia and AD has been postulated. The aim of the present study is to explore the relationship between lipid metabolism and ApoE isoforms in a large series of elderly subjects in relation to the presence or absence of AD.

METHODS

Of 332 referrals to a neurology clinic specializing in memory disorders, 146 were given a diagnosis of AD (age, mean +/- SD 76 +/- 13.1 years, 64.4% women) according to DSM-IIIR criteria. One hundred and seventy-six subjects were included as controls (age 80 +/- 5.6 years, 58% women). The ApoE phenotype was determined by the isoelectrofocalization method, cholesterol, triglycerides, phospholipids, ApoA and ApoB were determined by routine chemistry.

FINDINGS

A significant association was observed between the E4 allele and AD (chi2 = 13, p < 0.001) only below age 80. In the control group, cholesterol levels were found to be significantly higher in men but not in women with an E4 allele (6.35 +/- 1.3 mmol/l) as opposed to those without (5.8 +/- 1.2 mmol/l). ApoB levels were also found to be higher in the presence of ApoE4, with no gender effect. Within the AD group no significant relationship was found between ApoE4 and cholesterol levels (mean 6.05 +/- 0.9 mmol/l in E4-AD subjects versus 5.8 +/- 1.21 mmol/l in non-E4-AD subjects). Similar observations were made in relation to triglycerides and phospholipids.

INTERPRETATION

Our results demonstrate the disappearance of the ApoE4-raising effect on serum cholesterol, triglyceride and phospholipid levels in AD suggesting a more complex relationship between AD and lipid metabolism than has previously been supposed. This lipid abnormality may further contribute to the progression of AD.

Discrepancies between apolipoprotein E phenotyping and genotyping in the elderly

We estimated the frequencies of phenotype (isoelectric focusing; IEF) vs. genotype (PCR/Hhal) discordance in a sample of an aged population (> 65 years). Both phenotype and genotype techniques have been used in the study of apolipoprotein E (apoE) polymorphism in 125 elderly subjects. The discordance between phenotype and genotype was unresolved in 11 (8.8%) of the 125 unrelated subjects studied. We observed a significant association between the presence of the E4 allele and both Alzheimer's disease (chi2 = 13, p < 0.001) and increased cholesterol concentration (Mann Whitney, p < 0.03). These relationships were not affected by the techniques used. Our results indicate that transcriptional modulation and post-transductional modifications in normal ageing and in aged-related diseases may explain in part discrepancies between gene analysis and protein characterisation.

[Oxidative stress and chronic renal insufficiency: what can be a prophylactic approach?]

Cardiovascular diseases represent the first cause of mortality in chronic renal failure patients treated by hemodialysis. Alterations in lipid metabolism and oxidative stress are recognized as vascular risk factors. Their corrections could be of interest for atherosclerosis prevention. In order to evaluate interest of an therapeutic intervention, we have analyzed oxidative metabolism in hemodialysis patients by determining the production of oxygen reactive species (ROS), the level of defense mechanisms, and the balance between nitric oxide (NO) and ROS, responsible for anti- or proxidant effects of NO. During dialysis sessions performed with cellulosic membrane (Cuprophan) an increase in hydroperoxide production by platelets was noted (12 HETE) (5.62 +/- 0.94 pg); similarly, superoxide anion (O2(0)-) production by monocytes (fluorescence index: 115 +/- 24) and by polynuclear cells (fluorescence index: 115 +/- 24) was enhanced. On the other hand, anti-oxidant defenses were significantly reduced with a decrease in RBC SOC activity (0.92 +/- 0.06 U/mg Hg) and in RBC vitamin E (0.7 +/- 0.07 mg/l) concentration. We have demonstrated a profound alteration in the L-arginine/NO pathway consequently to an accumulation of NO synthases inhibitors or activators. The necessity to reduce the production of ROS during dialysis sessions justifies the use of more biocompatible membranes, such as modified cellulosic or synthetic membranes, decreasing leucocyte activation. In addition, NO synthetase inhibitors can be preferentially eliminated by convection. Finally, a supplementation with an exogenous anti-oxidant, such as oral vitamin E (500 mg/day for 6 months) normalizes RBC vitamin E levels and concomitantly allows a decrease in MDA concentrations In conclusion, oxidative metabolism alterations observed in hemodialysis are multifactorial: preventive measures include the use of a more biocompatible material, the reequilibrium of the NO/ROS balance, and supplementation with exogenous anti-oxidants.

Erythropoietin and oxidative stress in haemodialysis: beneficial effects of vitamin E supplementation

Oxidative stress can produce profound alterations to cellular membrane lipids, impairing cell metabolism and viability. This phenomenon, previously observed in haemodialysis patients, has been proposed as a significant factor in regard to haemodialysis-related shortened red blood cells (RBC) survival. In the present study, several parameters associated with oxidative stress were evaluated in a group of haemodialysis patients either receiving erythropoietin therapy (n = 12, mean erythropoietin dose 88 +/- 24 U/kg/week) or not receiving such therapy (n = 30), and in 38 controls. Malonyldialdehyde (MDA, nmol/ml), an end-product of lipid peroxidation, and RBC antioxidant systems were measured, including RBC alpha-tocopherol (RBC vitamin E, mg/l), RBC glutathione (GSH, nmol/mgHb), and RBC superoxide dismutase activity (SOD, U/mgHb). Plasma vitamin E concentrations were also evaluated. Finally, oral vitamin E supplementation (500 mg daily), an exogenous antioxidant, was administered for 6 months to seven patients from the dialysis group receiving erythropoietin while oxidative parameters were repeatedly evaluated and erythropoietin requirements monitored, in order to appreciate the therapeutic relevance of an antioxidant supplementation. An elevation of serum MDA was observed in all haemodialysis patients and a significant decrease in RBC vitamin E, despite normal serum vitamin E levels. Furthermore, the reduction in RBC vitamin E was more important in patients treated with erythropoietin. Vitamin E supplementation resulted in a significant increase in RBC vitamin E (from 0.3 +/- 0.1 to 1.2 +/- 0.2 mg/l of pellet) and a reduction in erythropoietin dose (from 93 +/- 24 to 74 +/- 26 U/kg/week) while maintaining stable haemoglobin concentrations. These results suggest that the oxidative stress could be one of the resistance factors to erythropoietin response in haemodialysis and that vitamin E supplementation could have a sparing effect on erythropoietin dosage requirement.