Band 47, Heft 3

B-type natriuretic peptide (BNP) has emerged as a reliable biomarker in patients with congestive heart failure. The mature, biologically active B-type natriuretic peptide, BNP (1–32) , is cleaved by corin from the 108 amino acid proBNP. However, in vivo as well as in vitro data demonstrated that this BNP (1–32) might be an ideal substrate for the endogenous aminopeptidase, dipeptidyl-peptidase IV (DPP IV). DPP IV removes the two amino terminal amino acids (Ser Pro) from BNP (1–32) to produce BNP (3–32) , which has been detected in plasma of patients with congestive heart failure. The biological effects of BNP (3–32) remain undetermined. In cultured human cardiomyocytes and fibroblasts, equimolar concentrations of BNP (1–32) and BNP (3–32) both exert similar biological effects, as evidenced by their cGMP (cyclic guanylate monophosphate) generating capacity. However, in a canine model, intravenous BNP (3–32) infusion resulted in less natriuresis, diuresis, and vasodilation compared to intravenous infusion of BNP (1–32) . The clinical relevance of these observations might be important for patients in whom the plasma BNP concentrations, measured by commercially available immunoassays, are high. Further studies exploring whether DPP IV inhibitors increase the bioavailability of BNP (1–32) , delay the progression of heart failure, and increase the efficacy of exogenous administration of BNP (1–32) in decompensated heart failure are needed. Clin Chem Lab Med 2009;47:248–52.

Background : In the past, different research groups could show that treatment of immune cells with inhibitors of post-proline splitting dipeptidyl aminopeptidases leads to functional changes in the immune system consistent with immunosuppression. This is due to the inhibition of proliferation of lymphocytes and the production of inflammatory cytokines of the TH 1 , TH 2 , and TH 17 cells as well as the induction of immunosuppressive cytokines, such as transforming growth factor-β1 (TGF-β1) and interleukin (IL)-1RA. Until recently, most of the effects of these inhibitors on immune functions were attributed to the inhibition of dipeptidyl aminopeptidase IV (DPIV/CD26). With the identification of new peptidases of the DPIV family (DASH) with the same or similar substrate specificity [fibroblast activation protein (FAP), DP8/9], the question arose whether and to what extent the inhibition of intracellularly localized enzymes, DP8 and DP9, contribute to the observed immunosuppression. In addition, members of the aminopeptidase N (APN) family are also involved in the regulation of immune functions. Hence, the concept of a combined targeting of both families of peptidases for treatment of inflammatory diseases is a promising strategy. Results/Conclusions : Summarizing data obtained from the usage of different non-selective and selective inhibitors of DPIV, DP8/9, FAP, and DPII, this review provides evidence that in addition to DPIV, DP8/9 also regulate the immune response via modulation of cell cycle progression and cytokine production. The strongest and most consistent effects in vitro were, however, observed with non-selective inhibitors for the suppression of DNA synthesis and cytokine production. Similar effects were provoked by APN inhibitors, which were also found to suppress DNA synthesis and the production of inflammatory cytokines in vitro. However, different mechanisms and signaling pathways appear to mediate the cellular effects resulting from the inhibition of either APN or DPIV family members. In particular, members of the APN family uniquely influence the function of CD4 + CD25 + regulatory T-cells. Consequently, the concomitant inhibition of both APN and DPIV enzyme families by means of two separate inhibitors or by binary inhibitors with specificity for both enzyme families (PETIR™, peptidase targeted immunoregulation) synergistically affects immune cells on the level of cell cycle regulation, suppression of TH 1 , TH 2 , and TH 17 cytokines as well as the activation of regulatory T-cells. Besides leukocytes, dermal cells as sebocytes, keratinocytes, and fibroblasts are also targeted by these inhibitors. This strongly suggests a broad potential of the multiple anti-inflammatory effects of PETIR™ in treatment of chronic inflammatory diseases, such as autoimmune diseases, allergies, and transplant rejections, as well as of inflammatory skin diseases, such as acne, psoriasis, rosacea or atopic dermatitis. The first active dual inhibitor, IP10.C8, has been developed by IMTM for the treatment of inflammatory skin diseases and has just entered the first phase II study. Clin Chem Lab Med 2009;47:253–61.

Dipeptidyl peptidase (DP) 6 and DP10 are non-enzyme members of the dipeptidyl peptidase IV family, which includes fibroblast activation protein, DP8, and DP9. DP6 and DP10 proteins have been shown to be critical components of voltage-gated potassium (Kv) channels important in determining cellular excitability. The aim of this paper was to review the research to date on DP6 and DP10 structure, expression, and functions. To date, the protein region responsible for modulating Kv4 channels has not been conclusively identified and the significance of the splice variants has not been resolved. Resolution of these issues will improve our overall knowledge of DP6 and DP10 and lead to a better understanding of their role in diseases, such as asthma and Alzheimer's disease. Clin Chem Lab Med 2009;47:262–7.

Background : Dipeptidyl peptidase IV (DP IV, CD26) and DP IV-like enzymes, such as dipeptidyl peptidase II (DP II), dipeptidyl peptidase 8 (DP8), and dipeptidyl peptidase 9 (DP9), have been recognized to regulate T lymphocyte activation. Lys[Z(NO 2 )]-thiazolidide (LZNT) and Lys[Z(NO 2 )]-pyrrolidide (LZNP), non-selective inhibitors of DP IV-like activity known to target DP IV as well as DP II, DP8, and DP9, suppress T lymphocyte proliferation in vitro. Moreover, these inhibitors are capable of attenuating the severity of autoimmune diseases, such as experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis, and experimental arthritis, a model of human rheumatoid arthritis, in vivo, particularly in combination with inhibitors of aminopeptidase N (APN, CD13) enzymatic activity. Methods : Here, we studied the influence of non-selective and selective inhibitors of DP IV-like enzymes on DNA synthesis in mitogen-stimulated splenocytes from wild-type C57BL/6 mice and DP IV/CD26-knockout (DP IV/CD26-KO) mice. Results : LZNT and LZNP, the non-selective inhibitors of DP IV-like activity, suppressed the DNA synthesis in stimulated splenocytes from wild-type and DP IV/CD26-KO mice to a comparable extent. Further, a selective inhibitor of DP8/DP9 activity was capable of suppressing DNA synthesis in mitogen-stimulated splenocytes of both wild-type and knockout mice to the same extent. In contrast, selective inhibitors of DP IV and DP II lacked this suppressive activity. Conclusions : Our data support the hypothesis that DP8 and/or DP9 represent additional pharmacological targets for the suppression of T cell proliferation and for anti-inflammatory therapy. Clin Chem Lab Med 2009;47:268–74.

Background : Treatment of diabetes type 2 using chronic pharmacological inhibition of dipeptidyl peptidase 4 (DP4) still requires an in-depth analysis of models for chronic DP4 deficiency, because adverse reactions induced by some DP4 inhibitors have been described. Methods : In the present study, a novel congenic rat model of DP4 deficiency on a “DP4-high” DA rat genetic background was generated (DA.F344- Dpp4 m /SvH rats) and comprehensively phenotyped. Results : Similar to chronic pharmacological inhibition of DP4, DP4 deficient rats exhibited a phenotype involving reduced diet-induced body weight gain and improved glucose tolerance associated with increased levels of glucagon-like peptide-1 (GLP-1) and bound leptin as well as decreased aminotransferases and triglycerides. Additionally, DA.F344- Dpp4 m /SvH rats showed anxiolytic-like and reduced stress-like responses, a phenomenon presently not targeted by DP4 inhibitors. However, several immune alterations, such as differential leukocyte subset composition at baseline, blunted natural killer cell and T-cell functions, and altered cytokine levels were observed. Conclusions : While this animal model confirms a critical role of DP4 in GLP-1-dependent glucose regulation, genetically induced chronic DP4 deficiency apparently also affects stress-regulatory and immune-regulatory systems, indicating that the use of chronic DP4 inhibitors might have the potential to interfere with central nervous system and immune functions in vivo. Clin Chem Lab Med 2009;47:275–87.

Background : Limited DNA resources or limited DNA targets in predominant backgrounds for genetic tests can lead to misdiagnosis. We developed a strategy to selectively increase the amount of minor targets through a specific pre-amplification procedure. Methods : We used the model of circulating cell free (ccf) male fetal DNA as a minor target in the predominant maternal plasma DNA to evaluate the strategy. The sex determining region (SRY) locus on the Y chromosome was used to identify ccf fetal DNA, and the human glyceraldehydes-3-phosphate dehydrogenase (GAPDH) gene was used to identify ccf total DNA in maternal plasma. We selectively pre-amplified the minor target SRY locus using the Expand Long Template PCR system and assessed the efficiency of the pre-amplification by real-time PCR, for both SRY and GAPDH, to compare the quantities of pre-amplified fetal DNA with those of maternal total DNA without pre-amplification. Results : The selected pre-amplification increased the amount of ccf fetal DNA dramatically (Wilcoxon test: p=0.000, the fold change=11,596). After selected pre-amplification, a proportion of 2.19% of the ccf fetal minor part in the predominant maternal component was changed up to 25,334%. The increased amounts of ccf fetal DNA found with the pre-amplification are not correlated to the amounts found without the procedure (r=−0.017, p=0.949). Conclusions : This strategy may be useful in genetic analysis with limited DNA resources and limited DNA targets in predominant background molecules. However, this approach is not suitable for quantitative assessments, due to the fact that quantitative imbalanced amplification was observed as a result of the pre-amplification procedure. Clin Chem Lab Med 2009;47:288–93.

Background : This study compared automated vs. manual tissue grinding in terms of RNA yield obtained from oral mucosa biopsies. Methods : A total of 20 patients undergoing uvulectomy for sleep-related disorders and 10 patients undergoing biopsy for head and neck squamous cell carcinoma were enrolled in the study. Samples were collected, snap-frozen in liquid nitrogen, and divided into two parts of similar weight. Sample grinding was performed on one sample from each pair, either manually or using an automated cell disruptor. The performance and efficacy of each homogenization approach was compared in terms of total RNA yield (spectrophotometry, fluorometry), mRNA quantity [densitometry of specific TP53 amplicons and TP53 quantitative reverse-transcribed real-time PCR (qRT-PCR)], and mRNA quality (functional analysis of separated alleles in yeast). Results : Although spectrophotometry and fluorometry results were comparable for both homogenization methods, TP53 expression values obtained by amplicon densitometry and qRT-PCR were significantly and consistently better after automated homogenization (p<0.005) for both uvula and tumor samples. Functional analysis of separated alleles in yeast results was better with the automated technique for tumor samples. Conclusions : Automated tissue homogenization appears to be a versatile, quick, and reliable method of cell disruption and is especially useful in the case of small malignant samples, which show unreliable results when processed by manual homogenization. Clin Chem Lab Med 2009;47:294–301.

Background : Protein and immunofixation electrophoresis of serum and urine are established as diagnostic aids for identifying monoclonal gammopathies. However, many patient sera sent to laboratories are not accompanied by urine samples and recent reports suggest the use of serum free light chain (sFLC) analysis in combination with serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE) could eliminate the need for urinalysis. The aim of the study was to assess the utility of sFLC measurement in addition to serum protein electrophoresis in the identification of patients with B-cell malignancies. Methods : A total of 952 serum samples were analysed by serum protein electrophoresis and those with abnormal bands were analysed by immunofixation. sFLCs were measured in a retrospective manner by automated assay. Results : In our study of 952 patient sera, it was found that FLC analysis identified 23 additional cases of B-cell malignancies which were missed by SPE. Conclusions : The additional malignancies identified by sFLC analysis add support for its inclusion in the routine screening protocol for B-cell malignancies. Clin Chem Lab Med 2009;47:302–4.

Background : Metabolomic studies have been applied to disease biomarkers selection. With the metabolomic technique, gas chromatography/mass spectrometry (GC/MS), human serum metabolites can be detected and identified. The purpose of this study was to investigate the serum metabolic profile of hepatitis B virus (HBV) infected cirrhosis patients and to detect disease biomarkers. Methods : HBV infected non-cirrhosis male subjects (n=20) and HBV infected cirrhosis male patients (n=20) participated in this experiment. Serum metabolome was detected through chemical derivatization followed by GC/MS. The high-flux metabolomic data were analyzed by stepwise discriminant analysis. Results : Out of the 41 metabolites detected in serum, we selected metabolites, including acetic acid, sorbitol, D-lactic acid, hexanoic acid, 1-naphthalenamine, butanoic acid, phosphoric acid, D-glucitol, and glucose, which in combination with each other could segregate the two groups. The error count was 0% for the non-cirrhosis group and 25% for the cirrhosis group. Conclusions : This technique can be used to select biomarkers for hepatic cirrhosis. Clin Chem Lab Med 2009;47:305–10.

Background : The objective of this study was to obtain baseline data on biomarkers of exposure (BoE) and biomarkers of potential harm (BoPH) in smokers, former smokers and never-smokers. Methods : This was a cross-sectional study of 80 healthy male and female volunteers over 21 years old, self-selected for smoking status. Subjects were pre-screened by medical staff at an independent clinical research unit, within 1 week prior to a single overnight residential visit and sample collection. Results : All BoE were able to differentiate between the two smoking groups and smokers from all non-smokers. There was a strong correlation between cigarettes smoked per day and total urinary nicotine equivalents (TNE; r=0.85). TNE correlated better with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol levels than cigarettes smoked per day (r=0.75 and r=0.56, respectively). Of the BoPH included in this study, seven (11-dehydro-thromboxane B2, 2, 3-dinorthromboxane B2, 8-epi prostaglandin F 2α , 8-hydroxy-2 deoxyguanosine, cis-thymidine glycol, low-density lipoprotein cholesterol and IgG) were significantly different between the group who smoked more cigarettes per day and never-smokers. These differences became more apparent and extended to the group who smoked 10 or less cigarettes per day, when total urinary recovery values were corrected for creatinine clearance. Conclusions : While BoE clearly differentiate between groups based on self-declared smoking status, most BoPH examined could not do so in a consistent manner. The dynamics of BoPH levels are not well understood. Future studies of BoPH should eliminate potential confounding factors and increase the number of subjects to allow the investigation of genetic polymorphism in metabolic pathways. Clin Chem Lab Med 2009;47:311–20.

Background : We constructed an artificial fusion gene tpN15 - 17 - 47 and then used the prokaryotic expression fusion protein rTpN15-17-47 as the coated antigen to establish a new enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of syphilis. Methods : tpN15 , tpN17 , and tpN47 genes were amplified separately by polymerase chain reaction (PCR) and then assembled into a fusion gene coding a trigeminy protein antigen by primer linking PCR. The target recombinant protein antigens rTpN15, rTpN17, rTpN-47, and rTpN15-17-47 were expressed and then purified antigens were immobilized on the surface of microplate wells for detecting Treponema pallidum -specific antibodies by ELISAs. Results : The relative positive rate of rTpN15-17-47-ELISA in 965 serum specimens of syphilis patients was 99.5%, which was higher than that of the T. pallidum hemagglutination assay (TPHA) (98.3%) (p<0.05) and much higher than that of the rTpN15-ELISA (83.1%), the rTpN17-ELISA (84.4%), the rTpN47-ELISA (82.1%), and the toluidine red unheated serum test (TRUST) (72.2%) (p<0.01). All the ELISAs and the TPHA in detecting serum specimens from 62 cases with systemic lupus erythematosus (SLE), 86 cases with rheumatic arthritis (RA), and 250 healthy cases were negative, but the TRUST was positive in five cases with SLE, seven cases with RA, and two healthy cases. Conclusions : The rTpN15-17-47-ELISA is a sensitive and specific serological screening or a diagnostic method for syphilis in the clinical setting. Clin Chem Lab Med 2009;47:321–6.

Background : The increased expression of heme oxygenase-1 content, a stress-response protein, directly correlates with the incidence of coronary heart disease. Down-regulation of hypoxia inducible factor-1α activity, a major downstream effector of the signaling pathways activated by hypoxia, increases cell survival after hypoxia. The ubiquitin system, a non-lysosomal pathway of protein degradation, is involved in processes of coronary heart disease. The aim of this study was to investigate the expression of heme oxygenase-1, hypoxia inducible factor-1α, and ubiquitin in both monocytes and lymphocytes isolated from patients at the mRNA and protein levels in different stages of coronary heart disease and their possible correlation. Methods : A total of 90 patients with coronary heart disease (30 acute myocardial infarction, 30 unstable angina pectoris, and 30 stable angina pectoris) were selected, and 30 cases with normal coronary artery served as controls. The mRNA and protein expression of heme oxygenase-1, hypoxia inducible factor-1α, and ubiquitin in monocytes and lymphocytes were examined by semi-quantitative reverse transcriptase polymerase chain reaction and Western blotting, respectively. Results : The mRNA expression of heme oxygenase-1 and ubiquitin was associated with the severity of coronary heart disease (p<0.05). There was no significant difference in hypoxia inducible factor-1α mRNA expression between the coronary heart disease patients and controls. The protein expression of heme oxygenase-1, hypoxia inducible factor-1α, and ubiquitin was significantly stronger in patients with coronary heart disease than in controls, and the expression levels increased with the severity of the disease. There was a positive association between heme oxygenase-1 and hypoxia inducible factor-1α and ubiquitin, antioxidative therapy with adrenergic receptor blocker, angiotensin-converting enzyme inhibitor or statins up-regulated the expression of heme oxygenase-1 and hypoxia inducible factor-1α. Conclusions : These data suggest that heme oxygenase-1, hypoxia inducible factor-1α, and ubiquitin are involved in the development and progression of coronary heart disease and thus may be useful biomarkers for coronary heart disease. Clin Chem Lab Med 2009;47:327–33.

Background : The incidence of coronary artery disease (CAD) is increasing at an alarming rate, especially in developing countries, such as India. It is often advocated that a vegetarian lifestyle could reduce the burden of CAD. However, in spite of a majority of Indians being vegetarians, the incidence of CAD is highest in this population. This may be due to deficiency of vitamin B12, a micronutrient, sourced only from animal products. Methods : Herein, we assessed the effect of vitamin B12 with respect to CAD in 816 individuals (368 CAD patients and 448 controls) recruited from a tertiary care center in New Delhi, India. Results : We found that vitamin B12 levels were significantly lower in CAD patients than in controls (p<0.0001). Also, vegetarians were found to have significantly lower vitamin B12 concentrations (p=0.0001) and higher incidence of CAD (p=0.01). Interestingly, elevated homocysteine levels, a hallmark of vitamin B12 deficiency, was not associated with CAD. In contrast, cysteine levels were significantly higher in CAD patients than in controls (p=0.004). Conclusions : We believe that, when vitamin B12 is deficient, homocysteine is rapidly metabolized via the transsulfuration pathway leading to increased cysteine levels. Clin Chem Lab Med 2009;47:334–8.

Background : Cardiovascular disease is the major cause of morbidity and mortality in chronic kidney disease (CKD) and early biomarkers are required which can predict disease and death in such patients. The aim of our study was to investigate if osteoprotegerin (OPG) could be a predictor of coronary artery calcification (CAC) and mortality in CKD. Methods : A total of 77 outpatients (32 with pre-dialysis CKD and 45 undergoing hemodialysis) were followed-up during 2 years. Measurements of CAC were performed using Siemens Multidetector CT software and calcium scores were measured according to the Agatston method. Results : OPG was an independent predictor of the Agatston score for CAC and correlated with the degree of CAC in pre-dialysis patients. A two-sample t-test characterized survivors as having a better glomerular filtration rate, lower Agatston scores, and lower serum levels of OPG. Kaplan-Meier survival curves separated survivors from non-survivors at plasma OPG cut-off levels of <3.1 ng/mL. A multivariable logistic regression analysis showed that OPG was an independent predictor of mortality from all causes in CKD patients. Conclusions : OPG predicted mortality in CKD patients and could be a valuable biomarker in early detection of CAC in these patients. Clin Chem Lab Med 2009;47:339–46.

Background : Cyclooxygenase-2 (COX-2) and prostacyclin synthase (PGIS) are enzymes involved in prostaglandin and prostacyclin synthesis, which have been linked to cardiovascular disease risk. We hypothesized that genetic variations altering the function of these enzymes would modify the risk of myocardial infarction (MI). Methods : In a Chinese case control study of MI patients (n=356) and healthy controls (n=350), we investigated the roles of polymorphisms in the PGIS gene ( CYP8A1 ) and the COX-2 gene ( PTGS2 ) using polymerase chain reaction-restriction fragment length polymorphism analysis. Results : The CC genotype of CYP8A1 and the –765CC genotype of PTGS2 were more common in the MI patients than in the control subjects (p=0.041, p=0.012, respectively). The odds ratio (OR) estimated by the combined analysis for the CYP8A1 CC and PTGS2 –765CC genotypes [OR=5.44; 95% confidence interval (CI): 3.12–7.23] was markedly higher than that estimated separately for the CYP8A1 CC genotype (OR=1.37; 95% CI: 0.95–2.85) or the PTGS2 –765CC genotype (OR=2.92; 95% CI: 1.78–5.76) alone. Conclusions : The CC genotype of CYP8A1 or the –765CC genotype of PTGS2 is associated with MI, respectively. Furthermore, the significantly combined effects of these two gene variants in the arachidonic acid metabolic pathway indicate that combining the effects of a modest number of genes, whose products are known to act in a pathophysiological manner, could be a useful method to explore the association of genetic polymorphisms and polygenic inheritance disease. Clin Chem Lab Med 2009;47:347–52.

Background : Conventional cardiac markers used for the biochemical diagnosis of acute coronary syndromes (ACS) have a high specificity but low sensitivity within 2–4 h of symptoms onset. The red blood cell distribution width (RDW), reflecting the size variability of circulating red blood cells, has been shown to be independently associated with an increased risk of major cardiovascular events. We assessed whether there is an association between RDW at admission and cardiac troponin T (cTnT) elevation in patients with chest pain. Methods : We analyzed RDW values in 2304 adult patients, who were consecutively admitted over a 1-year period to the local emergency department for chest pain suggestive of ACS. In all patients, a baseline blood sample was collected for routine haematological testing, whereas cTnT was measured at baseline and after 4, 6, and 12 h. Results : A total of 456 patients (19.8% of total) had ACS. These patients, all having cTnT≥0.03 μg/L up to 12 h from admission other than ischaemic electrocardiographic changes, had higher RDW than non-ACS patients [median 15.1%, (5th–95th percentiles) 13.2%–19.0% vs. 13.5%, 12.9%–17.1%, p<0.001]. On admission, the sensitivity and specificity of cTnT were 94% (25 false negative results) and 100%, respectively. The diagnostic accuracy of RDW, as calculated by the receiver operating characteristic curve analysis, was 0.705 (p<0.001). At the cut-off value of 14%, the clinical sensitivity and specificity of RDW on admission were 79% and 50%, respectively. In 21 out of 25 patients classified as false negative for cTnT on admission, the RDW was >14%. Accordingly, the diagnostic sensitivity of the two combined measurements on admission was 99%. Conclusions : As RDW is widely available to clinicians as a part of the complete blood count, and therefore incurs no additional costs, it might be considered with other conventional cardiac markers for the risk stratification of ACS patients admitted to emergency departments. Clin Chem Lab Med 2009;47:353–7.

Background : The performance of the BD Vacutainer ® PST™ II Tube for testing of special chemistry analytes was evaluated in comparison to serum and heparin plasma non-gel blood collection tubes. The comparison tubes included the BD Vacutainer ® Serum Plus Tube, the BD Vacutainer ® Lithium Heparin Plus Tube, and the BD Vacutainer ® Lithium Heparin Glass Tube. Methods : Tubes were drawn by routine venipuncture from 42 subjects according to a randomized draw order. Tubes were processed and centrifuged according to recommended handling procedures. Serum and plasma from the comparison tubes were aliquoted to secondary containers prior to analysis. Specimens were then tested for selected special chemistry analytes at two time intervals (initial time and after 24 h storage). Analytes tested included thyroid stimulating hormone, free thyroxine, total thyroxine, follicle stimulating hormone, luteinizing hormone, ferritin, cortisol, vitamin B12, folate, and testosterone. The data were collected and analyzed by analysis of variance and mean bias comparisons. Results : The performance of the BD Vacutainer ® PST™ II Tube was considered to be clinically equivalent to all three comparison tubes for all assays. Test results from the BD Vacutainer ® PST™ II Tube and from aliquots from the three comparison tubes at 24 h were considered to be clinically equivalent to those at initial time for all assays. Conclusions : The BD Vacutainer ® PST™ II Tube provided clinically equivalent results to serum and plasma non-gel tubes and good storage stability for the assays evaluated without the need to aliquot. Clin Chem Lab Med 2009;47:358–61.

Background : The Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines recommend maintaining serum parathyroid hormone (PTH) concentration between 150 and 300 pg/mL in patients with chronic kidney disease (CKD) stage 5. However, a marked inter-method variability in PTH measurement has been reported recently. The aim of this study was to evaluate whether harmonization of the results measured with two commercial kits known to produce significantly different serum PTH concentrations could be reasonably achieved by a simple procedure. Methods : The study comprised a total of 216 hemodialyzed patients in whom blood was collected immediately before a dialysis session. The patients were from three dialysis centers, which defined three groups (119, 34, and 63 patients for groups 1, 2, and 3, respectively). PTH was measured by two automated assays, the Elecsys (Roche Diagnostics) and Architect (Abbott Diagnostics) assays, in three different laboratories and with different lots of reagents. We arbitrarily chose the Roche assay as the reference method, because several studies had previously shown that the concentrations measured with this assay were very close to the Allegro assay used in the studies that defined the K/DOQI thresholds. Data are median (interquartile range). Results : The median PTH concentrations were higher (p<0.001) in the Architect assay [238 (140–434) pg/mL] when compared to the Elecsys assay [182 (109–338) pg/mL]. Bland-Altman plots in the three groups showed a similar proportional bias between both kits. The Architect PTH/Elecsys PTH ratios were similar in the three groups [1.30 (1.25–1.35), 1.30 (1.19–1.39), and 1.31 (1.25–1.35)], and the ratio was 1.30 (1.25–1.35) in the cohort (pooling the three groups). In the whole population, 53 patients (24.5%) were classified differently by the two kits according to the K/DOQI cut-off values. We divided the Architect values by 1.3 to obtain “corrected” values. These corrected Architect values were not different to the measured Elecsys values, and the Bland-Altman plot comparing the Elecsys and the corrected Artchitect values did not show any systematic proportional bias. Only six patients (2.8%) were still classified differently by the Elecsys and the corrected Architect concentrations. Conclusions : We propose to divide the PTH values measured with the Architect PTH assay by 1.3 so that the corrected values are almost identical to those measured with the Elecsys assay. Clin Chem Lab Med 2009;47:362–6.

Background : Cardiac troponins currently represent the preferred biomarkers for the detection of myocardial necrosis. The objective of the present study was to compare the performance of the Access ® AccuTnI ® assay (Beckman Coulter) measured on two different platforms, the UniCel ® DxI 800 and the Access ® 2 (Beckman Coulter). In particular, the serum cardiac troponin I (cTnI) concentration corresponding to 10% coefficient of variation (CV), the cTnI assay minimum detectable concentration (MDC), and the serum cTnI 99th percentile in healthy subjects were calculated. Methods : The Access ® AccuTnI ® is a paramagnetic particle chemiluminescent immunoassay. Imprecision profiles were determined according to the Clinical and Laboratory Standards Institute EP5-A protocol using serum pools. The MDC was calculated as mean+3 SD of 20 determinations of the zero calibrator during one run. The 99th percentile was determined analyzing serum samples from 679 healthy blood donors (523 males, 156 females; 18–71 years old). Results : cTnI concentrations are given in μg/L. 10% CV values (95% confidence interval, CI) were 0.0577 (0.0467–0.0750) (UniCel ® DxI 800) and 0.0486 (0.0255–0.0596) (Access ® 2). MDC values were 0.011 (UniCel ® DxI 800) and 0.012 (Access ® 2). The 99th percentile (95% CI) value was 0.0340 (0.0298–0.0410). Conclusions : Our data confirm the reliability of the evaluated cTnI assay and demonstrate the comparability of the cTnI values between the platforms studied. Clin Chem Lab Med 2009;47:367–71.

In 1997, the European Communities Confederation of Clinical Chemistry and Laboratory Medicine (EC4) set up a Register for European Specialists in Clinical Chemistry and Laboratory Medicine. The operation of the Register is undertaken by a Register Commission (EC4RC). During the last 10 years, more than 2000 specialists in Clinical Chemistry and Laboratory Medicine have joined the Register. In 2007, EC4 merged with the Federation of European Societies of Clinical Chemistry and Laboratory Medicine (FESCC) to form the European Federation of Clinical Chemistry and Laboratory Medicine (EFCC). A Code of Conduct was adopted in 2003 and a revised and updated version, taking account particularly of the guidelines of the Conseil Européen des Professions Libérales (CEPLIS) of which EFCC is a member, is presented in this article. The revised version was approved by the EC4 Register Commission and by the EFCC Executive Board in Paris on 6 November, 2008. Clin Chem Lab Med 2009;47:372–5.