Band 46, Heft 10

Background : We currently have guidelines that allow us to use bone densitometry in the diagnosis and management of osteoporosis. The role of biochemical markers of bone turnover (BTMs) is less well defined. Serum and urine BTM patterns in treated and untreated osteoporotic patients have been studied to help us define their role. The aim of this review is to present data which helps elucidate the current role and limitation of BTMs in the management of osteoporosis. Method : A search of the literature on BTMs was performed. References with keywords, such as bone turnover markers, biochemical markers, monitoring therapy and monitoring osteoporosis, were used. Results : Literature describing the nature and limitation of currently available BTMs was reviewed. The clinical use and limitation of BTMs in assessing fracture risk reduction, bone mineral density (BMD) and response to therapy is available, whereas definitive guidelines have not yet been created. Conclusions : BTMs offer a potential non-invasive and reliable way of assessing skeletal activity, studying drug effects and response to therapies, assessing fracture risk and predicting other skeletal parameters, such as bone loss, BMD and bone mass. A 30%–70% reduction in bone resorption markers can be achieved with antiresorptive therapy, and 30%–50% increase in bone formation markers with anabolic therapy. We recommend that clinicians understand and incorporate the measurement of BTMs in the management of osteoporosis. Clin Chem Lab Med 2008;46:1345–57.

A new diagnostic strategy for children with febrile urinary tract infections could be the routine use of procalcitonin assessment to identify children requiring closer follow-up since being at risk for kidney damage. A total of 11 studies were published between 1998 and 2007. Children with very high procalcitonin levels during urinary tract infections are likely to be at risk of renal damage and vesico-ureteral reflux. Therefore, the prediction of long-term renal damage showed contradictory results. However, high procalcitonin values at diagnosis and positive scintigraphic scans may suggest the need to investigate for vesico-ureteral reflux. Consequently, procalcitonin levels should be included in follow-up protocols for urinary tract infections to aid in decision making concerning scintigraphic scans and voiding cystourethrograms. Clin Chem Lab Med 2008;46:1358–63.

Background : Elevated plasma total homocysteine (tHcy), a risk factor for coronary artery disease (CAD), is due to defects in genes encoding for enzymes involved in tHcy metabolism or from inadequate status of vitamins involved in tHcy disposal. Methionine synthase (MS), a vitamin B 12 -dependent enzyme, catalyses the remethylation of homocysteine to methionine using a methyl group donated by 5-methyltetra-hydrofolate, which is the major circulating form of folate in the body. Functional genetic variants of the MS may alter tHcy as well as folate levels which are independent risk factors for CAD. The influence of a common genetic polymorphism 2756A>G of the MS gene ( MTR ) on plasma tHcy, folate and vitamin B 12 levels and its relation to the risk of myocardial infarction (MI) in a Tunisian case-control study was investigated. Methods : A total of 321 Tunisian patients with MI and 343 healthy controls were included in the study. The 2756A>G variant of the MTR was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Plasma tHcy was assessed with a fluorescent polarising immunoassay method. Plasma vitamin B 12 and folate were determined by microparticular enzyme immunoassay and ion-capture, respectively. Results : A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with MI had a frequency of 1.9% for the GG genotype, 26.2% for the AG genotype and 72% for the AA genotype. Controls had a frequency of only 0.9% for the GG genotype, 18.7% for the AG genotype and 80.5% for the AA genotype (χ 2 =6.97, p=0.03). The MI patient group showed a significant higher frequency of the G allele compared to controls (0.149 vs. 0.101; OR 1.55; 95% CI 1.10–2.18; p=0.008). The association between the 2756A>G variant in the gene encoding MS and MI was no longer significant after adjustment for other well-established risk factors. When clinical and laboratory values were compared amongst genotypes in the study groups, no significant differences were noted. Conclusions : The present study showed a significant but not independent association between the 2756A>G polymorphism of the MTR (presence of G allele) and MI in the Tunisian population. Clin Chem Lab Med 2008;46:1364–8.

Background : Endothelial nitric oxide synthase (eNOS) produces nitric oxide, which plays a role in vasodilatation and in the regulation of cell growth and apoptosis. eNOS-deficient mice have impaired cardiac development resulting in congenital heart defects (CHDs). In humans, a single nucleotide polymorphism in the gene coding for eNOS (894G>T) is associated with birth defects. Methods : We investigated the eNOS 894G>T polymorphism in relation to CHDs using a case-control study and a case-parent study. Possible interaction with maternal cigarette smoking during pregnancy and periconceptional folic acid supplementation was also investigated in a case-only approach. Results: The eNOS 894G>T polymorphism was genotyped in 170 CHD-affected children, in 161 of their mothers, 215 control children and 240 control women. For the case-parent study, 135 complete triads were available. The sum of eNOS 894 GT and TT vs. GG genotypes in children was associated with increased CHD risk [odds ratio, OR 1.5 (95% CI 1.03–2.31)]. There was no preferential transmission of the 894T allele [OR 1.2 (95% CI 0.81–1.69)]. Overall, the maternal eNOS 894 GT or TT vs. GG genotypes were not associated with increased CHD risk. The maternal 894TT genotype in combination with maternal smoking was associated with an increased risk, particularly for a subgroup of other than conotruncal heart defects [OR 3.3 (95% CI 1.00–11.1)]. No interaction with periconceptional folic acid supplementation was observed. Conclusions: Our data indicate that the eNOS 894G>T polymorphism is associated with increased CHD risk. The study also provides evidence of a possible gene-environment interaction effect on CHD risk between the maternal eNOS 894G>T variant and maternal cigarette smoking during pregnancy. This observation should be interpreted with caution because of the relatively small subgroups. Further study in a larger group of CHD subjects is required. Clin Chem Lab Med 2008;46:1369–75.

Background : Mutations in BRCA1 and BRCA2 genes are associated with family predisposition to breast and ovarian cancer. Novel screening methods are required for efficient and rapid detection of sequence variants in cancer patients and their family members. Methods : The screening for variants in the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 in Croatia was performed by a high-resolution melting approach, which is based on differences in melting curves caused by variations in nucleotide sequence. This is the first screening in Croatia on elderly healthy women with no family history of cancer. BRCA1 screening was performed on 220 and BRCA2 screening on 115 samples. Results : In a population well beyond the average age of breast/ovarian cancer onset, 21 different sequence variants in the BRCA1 gene (one novel: c.5193+49_50delTA ) and 36 variants in the BRCA2 gene (7 novel: c.459A>C , c.3318C>A , c.4412_ 4414delGAA , c.4790C>A , c.6264T>C , c.9087G>A , and c.9864A>G ) were detected. Conclusions : Nine BRCA1 and seven BRCA2 known variants appeared with such high frequencies that they could be declared as harmless in this population. Eight BRCA1 high frequency variants, located further from the promoter region, appear to be strongly correlated. Three novel variants that changed the amino acid sequence of the BRCA2 protein (two missense base substitutions, c.3318C>A and c.4790C>A , and one codon deletion c.4412_4414delGAA ), appearing only once, were predicted to have no potential effect on protein structure and function. Clin Chem Lab Med 2008;46:1376–83.

Background : Hybridization chain reaction (HCR) is an attractive method to amplify the signal of targeted nucleic acids. Methods : Fluorescent HCR systems, including basic fluorescent HCR and real-time fluorescent HCR, were developed and evaluated in the present study. Results : Fluorescent HCR but not basic HCR could be performed by enzyme-free signal amplification in a single closed tube. In real-time fluorescent HCR, which was performed in only approximately 10 min, hybridization curves and hybridization logarithmic curves were developed to depict the hybridization thermodynamic kinetics of HCR. The results showed that the starting point of polymerization of fluorescent HCR was dependent on the concentration of initiator I. The low sensitivities of basic and fluorescent HCR (i.e., 0.05 μM) might be determined by the intrinsic features of monomer hairpins used in all of the above HCR systems. Although the sensitivities were not improved in fluorescent HCR compared to basic HCR, fluorescent HCR has a potential role in identification and analysis of amplified nucleic acid targets acting as initiators in HCR. Conclusions : Fluorescent HCR, including basic fluorescent HCR and real-time fluorescent HCR, is a fast, simple and robust method to identify various analytes in a single closed tube. Clin Chem Lab Med 2008;46:1384–7.

Background : X-linked microsatellites represent an efficient complement of autosomal and Y-chromosomal markers in forensic and kinship analysis. Methods : DXS337 (n=208), DXS101 (n=208), HPRTB (n=206), DXS8377 (n=220), and DXS7423 (n=213) were genotyped in male and female samples from a Western Mexican Mestizo population using singleplex systems and polyacrylamide gel electrophoresis. Results : Genotype distributions did not deviate from Hardy-Weinberg expectations, and pairwise allele combination analysis was consistent with independent segregation for every marker (p>0.05). Allele frequencies were not different by gender. Differences in allele distribution with respect to Caucasian population data (DXS101, HPRTB, DXS8377, DXS7423) seem attributable to the native Mexican component. For the set of five markers, the combined power of discrimination and the probability of exclusion in paternity tests in trios were greater than 0.999. Conclusions : The present data reveal that the panel of five X-short tandem repeats analyzed is highly informative in forensic identity and parentage studies in Western Mexico. Clin Chem Lab Med 2008;46:1388–90.

Background : Owing to the high correlation between the level of prolyl-4-hydroxyproline dipeptide in non-hydrolyzed urine and that of 4-hydroxyproline in hydrolyzed urine, we examined whether the dipeptide might function as a valuable marker of bone turnover. Methods : Based on densitometric measurements, 68 postmenopausal women were divided into groups of non-osteopathic, osteopenic and osteoporotic subjects. The dipeptide and current urinary resorption markers were assayed in morning urine, the former using liquid chromatography, the others plus serum formation markers by means of immunoassay procedures. Together with the assay of basal levels, diet-related changes and healing effect of yearly alendronate therapy were assessed. Results : Concentration levels in controls and osteoporotic subjects differed significantly; receiver operating characteristics yielded sensitivity of 0.743, specificity of 0.908, area under curve of 0.903, and cut-off of 10.2 μmol/mmol of creatinine. Spearman rank correlation showed the highest pair coefficient between the dipeptide and osteocalcin. Diet-related changes were not found. Following therapy, a significant decline occurred already within a trimester, whilst with the other resorption markers not until 6 months. Conclusions : The ease of the dipeptide assay in non-hydrolyzed urine surpasses that of hydroxyproline, and the results present the compound as a real competition to other commonly assessed markers in osteopathies. Clin Chem Lab Med 2008;46:1391–7.

Background : Sepsis is a disease with high incidence and lethality and is accompanied by profound metabolic disturbances. In mammalian methionine metabolism, S-adenosylmethionine (SAM) is produced, which is important in the synthesis of neurotransmitters and glutathione and as an anti-inflammatory agent. The degradation product and antagonist of SAM is S-adenosylhomocysteine (SAH). In this study, we investigated changes in methionine metabolism in a rodent model of sepsis. Methods : Sepsis was induced in male Wistar rats (n=21) by intraperitoneal injection of bacterial lipopolysaccharide (10 mg/kg). Controls (n=18) received vehicle only. Blood was collected by cardiac puncture 24 h later. Puncture of the suboccipital fossa was performed to collect cerebrospinal fluid (CSF). Methionine metabolites were measured using stable isotope dilution tandem mass spectrometry. Plasma total homocysteine and cysteine were measured by HPLC using fluorescence detection. Glutathione was assayed using a modified enzymatic microtiter plate assay. Results : We observed significantly higher plasma levels of SAM (p<0.001) and SAM/SAH ratio (p=0.004) in septic animals. In CSF, there was also a trend for higher levels of SAM in septic animals (p=0.067). Oxidative stress was reflected by an increase in the ratio of oxidized/reduced glutathione in septic animals (p=0.001). Conclusions : Sepsis is associated with an increase in SAM/SAH ratio in plasma and CSF in rodents. This indicates an altered methylation potential during sepsis, which may be relevant for sepsis-associated impairment of transmethylation reactions, circulation and defense against oxidative stress. If verified in humans, such findings could lead to novel strategies for supportive treatment of sepsis, as methionine metabolism can easily be manipulated by dietary strategies. Clin Chem Lab Med 2008;46:1398–402.

Background: Myeloperoxidase (MPO) neutrophils have been considered an important pathophysiological factor in oxidative stress. Mainly through generation of hypochlorous acid in the phagosome, unchecked activity may lead to inactivation of important proteins through modification of tyrosine and other residues. This has been shown for low-density lipoprotein, apolipoprotein AI and paraoxonase 1 (PON-1). Notably, plasminogen has 29 tyrosine residues and we previously demonstrated that it can be inactivated by nitration of these residues. Methods : We hypothesized that plasminogen can also be inactivated by HOCl/OCl − in a similar manner to PON-1, and that this inhibition can be counteracted by cysteine or taurine. In the present study we compared the effects of HOCl/OCl − on these two plasma proteins and explored the effects of inhibitors. Results : Our study revealed that HOCl/OCl − inhibits streptokinase-induced plasmin activity at low micromolar concentrations that may well occur in vivo at sites of inflammation (IC 50 =40 μmol/L). This inhibitory effect occurs at much lower concentrations than those that inhibit PON-1 activity (IC 50 120 μmol/L). The inhibition is paralleled by an increase in 3-chlorotyrosine adducts in the protein. HOCl/OCl − inhibition of plasminogen and 3-chlorotyrosine formation are blocked by cysteine; taurine shows much lower protection. HOCl/OCl − does not modify the activation of plasminogen by streptokinase, leaving inactivation of active site Tyr 614 (possibly directed by Lys 615) as a very attractive hypothesis to explain the effect and the high sensitivity found. Conclusions: Since neutrophils have been shown to secrete HOCl/OCl − up to 100 μmol/L, inactivation of plasmin molecules by neutrophil-generated HOCl/OCl − could partly explain the increased thrombo-genicity observed in inflammatory conditions, in smokers and in other diseases. Thus, dietary intervention or the use of thiols or large doses of taurine compounds may be useful as coadjuvant therapeutic measures. Clin Chem Lab Med 2008;46:1403–9.

Background : Elevated γ-glutamyltransferase (GGT) has emerged as an independent predictor of cardiovascular disease (CVD) which is increasingly viewed as an inflammatory disease. Thus, the mechanism underlying the link between elevated GGT and CVD may be inflammation. Methods : We examined the relationship between GGT and C-reactive protein (CRP) levels and white blood cell (WBC) count in 4562 Korean adults (2104 men, 2458 women). The odds ratio (OR) and 95% confidence interval (CI) for high CRP and WBC count (≥75th percentile) for both men and women were calculated across each quartile of serum GGT. Results : Results for the OR (95% CI) for high CRP levels by GGT quartiles were 1.00, 1.67 (1.21–2.29), 2.10 (1.51–2.93) and 2.51 (1.81–3.60) in men, and 1.00, 1.05 (0.65–1.68), 1.45 (0.79–2.02) and 2.16 (1.37–3.41) in women after adjustment for age, smoking status, alcohol intake, exercise, body mass index, blood pressure, fasting plasma glucose, triglyceride, high-density lipoprotein-cholesterol, and uric acid. Similarly, positive associations between serum GGT and WBC count were also observed. Conclusions : The present study demonstrates a positive correlation between GGT and two markers of inflammation, serum CRP and WBC count. Our findings suggest that serum GGT may be a surrogate inflammatory marker and a useful additional measure in assessing cardiovascular risk. Clin Chem Lab Med 2008;46:1410–5.

Background : A limitation of isotopic assays is decay of the radioactive signal and the need for a calibration curve in each run. Thus, calibration transfer has been proposed for immunoradiometric analysis (IRMA). The present study was undertaken to establish the main methodological issues applied to the determination of thyroglobulin (Tg). Methods : Serum samples were analyzed at a different experimental time than Tg standards. Tg concentrations were then determined using a transferred calibration curve estimated from a calibration model based on a three-parameter antigen-antibody interaction model and a decay kinetic constant. Results : A kinetic constant for decay of the radiolabeled antibody signal was calculated (–0.018± 0.002 day −1 ). This strategy avoided full recalibration, despite degradation of the radiolabeled immunoreagents or experimental variations. The calibration transfer was validated using addition, dilution and recovery protocols. Repeated analyses of serum samples were performed during the life of the commercial immunoreagents, and concentrations were determined using daily and transferred calibration curves. Results were statistically comparable, but significant reductions in reagent consumption, analysis time, radioactive waste and staff time were obtained. Conclusions : Transferred curves can be used to analyze samples by IRMA without simultaneous measurement of standards, and provide reliable concentrations. This principle has been demonstrated for Tg determination, but the key issues to extend to other IRMA methods have been established. Clin Chem Lab Med 2008;46:1416–22.

Background : Colorectal cancer is one of the most common cancers of the gastrointestinal tract and the fourth cause of cancer death in the world. It has been shown that local chronic inflammation may lead to colorectal carcinogenesis via adenomatous polyps. Interleukin-6 and C-reactive protein are biomarkers of inflammation and indicators of the immune response to tumors. Methods : Serum levels of interleukin-6, carcinoembryonic antigen and carbohydrate antigen 19-9 were determined using immunoenzymatic assays, and C-reactive protein concentrations by immunoturbidimetric kits in 76 colorectal cancer patients before surgery, in 38 colorectal adenoma patients and in 35 healthy controls. Results : Serum levels of interleukin-6, C-reactive protein and carcinoembryonic antigen were significantly higher in cancer patients when compared to adenoma patients and healthy subjects, and increased in more advanced stages of disease and in patients with non-resectable tumors. Based on Cox's analysis, the elevated preoperative serum level of C-reactive protein was an independent significant prognostic factor for patients' survival. Conclusions : Our findings suggest the usefulness of interleukin-6 in the diagnosis of colorectal cancer patients and C-reactive protein in the survival prognosis. Clin Chem Lab Med 2008;46:1423–8.

Background : Oxcarbazepine is an antiepileptic drug (AED) used to treat partial seizures as a monotherapy or adjunctive therapy. Oxcarbazepine is metabolized in the liver to its active metabolite, 10,11-dihydro-10-hydroxy-carbamazepine (MHD). Optimal therapeutic effect and minimal toxicity can be achieved through monitoring MHD. Methods: Serum/plasma was mixed with internal standard (5-ethyl-5-p-tolylbarbituric acid) in methanol and centrifuged for 10 min. The mobile phase consisted of phosphate buffer and acetonitrile (466:168 v/v). The supernatant was analyzed by liquid chromatography (LC) with UV detection at 210 nm. Results : The linearity ranged from 1.0 to 50.0 μg/mL with analytical recovery of 101.3%–110.8%. The limit of quantification was 1.0 μg/mL. The intra-assay coefficient of variation (CV) was 7.0% and 2.0% for serum samples spiked at 16.3 and 35.8 μg/mL, respectively. The inter-assay CV was 4.3% and 2.3% for serum controls at 7.2 and 23.8 μg/mL, respectively. The method was correlated with a commercial LC-mass spectrometry method using 41 leftover patient samples containing MHD at concentrations of 1.0–36.4 μg/mL, showing a slope of 1.09, an intercept of 1.2 and r=0.9520. No interference was observed from commonly administered AEDs. Commercial controls containing more than 100 therapeutic drugs and endogenous substances were also tested and showed no interference. Conclusions : This method is simple and effective for monitoring MHD in serum/plasma. Clin Chem Lab Med 2008;46:1429–33.

Background : Usual coffee consumption may decrease insulin resistance and type 2 diabetes incidence, and reduce cardiovascular disease risk. As a mechanism, coffee-induced lower levels of C-reactive protein (CRP), a marker for the development of these diseases, can be considered. The associations between coffee consumption and CRP should be established by studies on various populations, yet studies in Japanese people, who do not necessarily consume as much coffee daily, are limited. Methods : In total, 459 community-living Japanese women, aged 23–83 years, were investigated. Clinical data including age, body mass index, blood pressure, HbA 1c , serum high sensitive CRP (hsCRP) and lifestyle habits, such as coffee consumption, were included in the analyses. All analyses were performed in two groups of the population, i.e., age <60 and ≥60 years. Results : Significantly lower levels of hsCRP were observed in the group of ≥1 cup/day than in that of <1 cup/day in the respective groups of <60 years (p=0.001) and ≥60 years (p<0.0001). In multiple regression analysis, coffee consumption was significantly, independently and inversely correlated to log-hsCRP in the respective groups of <60 years (p=0.017) and ≥60 years (p<0.0001). Conclusions : It was noteworthy that the benefits of coffee consumption, even if ≥1 cup/day, on serum hsCRP levels were confirmed in Japanese women, following similarly to other ethnic data. Clin Chem Lab Med 2008;46:1434–7.

Background : Measurement of parathyroid hormone (PTH) is central in the investigation of pathologies of bone and mineral ion metabolism. Knowledge of the biological variation of an analyte forms an essential part of evaluating a new analyte, enabling the objective assessment of changes in serial results and the utility of reference intervals, as well as establishing laboratory quality specifications. Methods : This study determined the biological variation of PTH in 20 healthy individuals, which was calculated according to the familiar methods outlined by Fraser and Harris. Results : The within-subject variation was 25.3% and the between-subject variation was 43.4%. The critical difference for sequential values significant at p<0.05 was calculated as 72%. The within-subject variation forms a relatively small part of the reference interval, shown by the low index of individuality of 0.58. Objective analytical quality goals have also been established, revealing achievable optimum performance for imprecision of ∼6%. The desirable analytical bias goal was ∼12%. Conclusions : This study has objectively shown that the analytical precision of current instruments is being achieved contrary to the known problems surrounding the analytical bias for PTH assays. The limitations of using reference intervals for PTH, both in diagnoses and monitoring, are shown. Clin Chem Lab Med 2008;46:1438–42.

Background : Pneumatic tube transport of blood samples reduces turnaround times and labour. However, the preanalytical effects on new clinical chemistry parameters and instruments are not fully known. The aim of this study was to evaluate the effect of pneumatic tube transport on haematology and coagulation parameters, including platelet function with PFA-100 ® , and global coagulation with a thromboelastograph. Methods : Paired venous blood samples from healthy volunteers were obtained before and after 1 week of treatment with acetylsalicylic acid. One sample was transported by pneumatic tube transport, while the other remained in the laboratory. Results : No preanalytical effect of pneumatic tube transport could be seen for most haematology and coagulation parameters, as well as analysis with PFA-100 ® . For the thromboelastographic analysis, time to clot formation was shorter (–16%, p=0.037) in the transported samples. Treatment with acetylsalicylic acid had no effect on the majority of the test results. Conclusions : Pneumatic tube transport does not introduce preanalytical errors when transporting samples for analysis of routine haematology, coagulation parameters and platelet function with the PFA-100 ® . We recommend manual transport of samples for analysis with thromboelastographic techniques. Clin Chem Lab Med 2008;46:1443–9.

Background : Ferritin standardisation is problematical due to the heterogeneity of ferritin isoforms and the antibodies used in its immunoassay, and the lack of a reference measurement procedure. We investigated the performance of the 1st (liver), 2nd (spleen) and 3rd (recombinant) International Standards (ISs) for ferritin in major assays. Methods : The ferritin in a serum pool ‘spiked’ with either the 2nd or 3rd IS for ferritin was measured by 52 laboratories using five automated methods and the recovery of the target values calculated. A smaller serum pool was ‘spiked’ with the 1st IS for a limited recovery exercise. The ferritin values of five serum samples were also measured and recalculated relative to the ISs. Results : Recoveries of each of the 2nd and 3rd ISs were 90%–110% for four of five methods; recoveries of the 1st IS were 104% and 111% for two of three methods claiming traceability to this IS. One method significantly over-recovered each of the IS (124%–155%). Recalculating the ferritin values of the serum samples relative to the IS reduced the overall inter-method agreement, largely because of the anomalous over-recovery of the IS by one method. Conclusions : The use of the 3rd IS to standardise assays will minimise assay drift due to manufacturers adopting a ‘harmonisation’ approach in which the calibration is adjusted to conform to overall mean values. Standardisation against the current IS also ensures compliance with the European Union In-Vitro Diagnostic Directive which requires traceability of assay calibrators to reference materials of a higher order. Assay drift may result in poor sensitivity and specificity in the diagnosis of iron status, and would require laboratories to continually re-evaluate reference intervals. Clin Chem Lab Med 2008;46:1450–7.

Background : With the improvement of capillary electrophoresis, much progress has been made in terms of sensitivity and automation, but the interpretation of the patterns, actually, depends totally on expert personnel. The aim of this work was to evaluate Neurosoft-Sebia, an expert system developed to discriminate between regular and anomalous serum protein electrophoresis patterns performed on Capillarys™2. Methods : Neurosoft-Sebia, based on six auto-associative neural networks, was trained to create the initial knowledge base. In the tuning phase, 3000 electrophoretic patterns were performed in three different laboratories, and the discordances between human experts and Neurosoft-Sebia classifications were added to the initial knowledge base. Finally, the performances of Neurosoft-Sebia were evaluated using a benchmark dataset. Results : The initial knowledge base was created with 2685 fractions. In the tuning phase, 241 discordances were found: 56 as regular by Neurosoft-Sebia and anomalous by human experts, and 185 as anomalous by Neurosoft-Sebia and regular by human experts. Sensitivity values were evidenced as the ability of Neurosoft-Sebia in selecting anomalous fractions, with an increase from 66.67% using the initial knowledge base to 97.40% using the enriched knowledge base. Conclusions : This work demonstrated how the ability of Neurosoft-Sebia in selecting anomalous pattern was comparable to that of human experts, saving time and providing rapid and standardized interpretations. Clin Chem Lab Med 2008;46:1458–63.

Background : Prolonged laboratory turnaround time (TAT) contributes to prolonged length of stay in emergency departments (EDs). The TAT of laboratory test results is a common key performance indicator by which clinicians and regulatory bodies evaluate laboratory performance. Establishing satellite laboratories in EDs staffed by laboratory technologists is one approach towards reducing TAT. Methods : TAT data were collected for three time intervals: (a) sampling time to time samples received in the laboratory (transportation time), (b) sample received in the laboratory until results were available for viewing on the laboratory information system monitor or collection by ED staff (within laboratory TAT), and (c) sampling to availability of results (total TAT, e.g., a+b). The target was to achieve a median within laboratory TAT of 45 min for samples received from the ED. Results : The median transportation times for samples to be delivered to the central and satellite laboratory were 22 min and 1 min, respectively (p<0.0001). The median within laboratory TATs were 45 [95% confidence interval (CI) 43–49] and 34 (95% CI 33–35) min for the central and satellite laboratories, respectively (p<0.001). Conclusions : A satellite laboratory in the ED can significantly reduce laboratory TAT. Clin Chem Lab Med 2008;46:1464–7.

Background : Capillary zone electrophoresis (CZE) is a well-accepted automated method used to separate serum proteins and detect monoclonal components. CZE uses ultraviolet detection at 214 nm to directly quantify proteins via peptide bonds. Any substance that absorbs at 214 nm and is present in serum can potentially interfere with CZE analysis. This has been reported for radio-contrast media and antibiotics. Methods : Here we describe a peak on the anode side of the α 2 -globulin fraction caused by the antibiotic ampicillin-sulbactam (Unacid ® ). Results and conclusions: Extra peaks that can be misinterpreted as monoclonal components can be present in almost all electrophoretic fractions of CZE. Immunosubtraction or immunofixation is always required to rule out these conditions. Clin Chem Lab Med 2008;46:1468–9.

We present a practical protocol for the assignment of values to serum proteins in a Target Material using a Reference Material. This protocol is based on the model of Direct Value Transfer between serum matrices and is intended to improve the value assignment of commercial calibrators using the Reference Material CRM 470 (now labeled ERM-DA 470) or similar reference materials. The procedure describes the general as well as the practical principles involved in the value assignment (with examples). The practical transfer protocol is based on multiple assays of 6 dilutions of the Reference Material and 6 dilutions of the Target Material. The transfer protocol requires several measurements a day repeated on several days, an important prerequisite being that all reconstitutions and dilutions are controlled by weighing thus reducing uncertainty in the transfer. In open systems that allow the use of the Reference Material as calibrator and the Target Material as samples, the proportionality of the two materials (the presence or absence of matrix effects) can now be directly assessed by evaluating a single regression plot. If no matrix effects are found, the regression line will pass through zero with a slope equal to the ratio of the concentrations of the two materials. In closed systems, the dedicated commercial calibrator has to be used as such; the Reference Material and the Target Material are now assayed as samples against this calibrator. Two regression plots are therefore obtained; if no matrix effects are present among the two materials and the calibrator, both the Reference and Target Materials will show zero intercepts, and the ratio of the two slopes will equal the ratio of the concentrations. Clin Chem Lab Med 2008;46:1470–9.