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November 1, 2007
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In this comprehensive review, we summarize the current state-of-the-art of neurochemical biomarkers for Alzheimer's disease. Predominantly, these biomarkers comprise cerebrospinal fluid biomarkers directly related to the pathophysiology of this disorder (such as amyloid β protein, tau protein). We particularly pay attention to the innovations in this area that have been made in technological aspects during the past 5 years (e.g., multiplex analysis of biomarkers, proteomics), to the discovery of novel, potential biomarkers (e.g., amyloid β oligomers, isoprostanes), and to the extension of this research towards identification of biomarkers in plasma. Clin Chem Lab Med 2007;45:1421–34.
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November 1, 2007
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Surface-enhanced laser desorption time of flight mass spectrometry (SELDI-TOF-MS) is an important proteomic technology that is immediately available for the high throughput analysis of complex protein samples. Over the last few years, several studies have demonstrated that comparative protein profiling using SELDI-TOF-MS breaks new ground in diagnostic protein analysis particularly with regard to the identification of novel biomarkers. Importantly, researchers have acquired a better understanding also of the limitations of this technology and various pitfalls in biomarker discovery. Bearing these in mind, great emphasis must be placed on the development of rigorous standards and quality control procedures for the pre-analytical as well as the analytical phase and subsequent bioinformatics applied to analysis of the data. To avoid the risk of false-significant results studies must be designed carefully and control groups accurately selected. In addition, appropriate tools, already established for analysis of highly complex microarray data, need to be applied to protein profiling data. To validate the significance of any candidate biomarker derived from pilot studies in appropriately designed prospective multi-center studies is mandatory; reproducibility of the clinical results must be shown over time and in different diagnostic settings. SELDI-TOF-MS-based studies that are in compliance with these requirements are now required; only a few have been published so far. In the meantime, further evaluation and optimization of both technique and marker validation strategies are called for before MS-based proteomic algorithms can be translated into routine laboratory testing. Clin Chem Lab Med 2007;45:1435–49.
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October 31, 2007
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Background : Genes that regulate iron metabolism may be involved in increasing brain iron content in Parkinson disease (PD). The ferritin L-chain is one of these genes, but the rare insertional mutations that cause neuroferritinopathy with basal ganglia degeneration have not yet been identified in PD. Methods : We used denaturing HPLC (DHPLC) to investigate 124 PD patients and 180 controls for variations in the coding and in the 5′ untranslated regions of the H- and L-ferritin genes. Results : In the H-ferritin gene, we found one new and rather common intronic polymorphism and the K54R substitution in two controls. The L-ferritin gene showed a very common L55L polymorphism and four other types of DNA variations, three of which were in the patient cohort. A mutation of the conserved His133 to Pro was found in a PD patient and in his daughter. The patient did not show signs of neuroferritinopathy, but the mutation was associated with low L-ferritin levels and with mild chronic anemia. Conclusions : The results support the hypothesis that DNA variations in the ferritin genes are not a common cause for PD. Clin Chem Lab Med 2007;45:1450–6.
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October 31, 2007
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Background : Although it has been shown that high-molecular weight adiponectin is an active form, few studies have attempted to clarify the relationship between high molecular weight adiponectin and markers linked with cardiovascular diseases in the general population. Methods : We screened 236 Japanese study participants recruited from the general population, residing in one large and four small islands. In addition to serum lipids and lipoproteins, serum total adiponectin and each multimer were measured. The genotype single-nucleotide polymorphism 276G>T was detected in real-time PCR with LightCycler ® hybridization probes, using fluorescent-labeled nucleotides. Results : Multiple linear regression analysis showed that high-molecular weight adiponectin, as well as total adiponectin, were significantly correlated with body weight, body mass index, high-density lipoprotein cholesterol and triglycerides. Total adiponectin and high-molecular weight adiponectin concentrations were not significantly different between GG and TX (GT and TT) genotypes of 276G>T polymorphism in the adiponectin gene. Interestingly, no differences were observed for participants from the large island between GG and TX genotypes with regard to both total adiponectin and high-molecular weight adiponectin, whereas significant differences were observed for those from the small islands. Conclusions : Our results show that total adiponectin and high-molecular weight adiponectin are associated with similar factors in the general population. Furthermore, different effects of 276G>T for participants from small and large islands suggest that regional background due to geographic barriers may control the effects of 276G>T on adiponectin concentrations. Clin Chem Lab Med 2007;45:1457–63.
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October 31, 2007
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Background: The identification of Brucella isolates using conventional microbiological techniques is time-consuming and hazardous. We therefore assessed the performance of real-time PCR assays for the identification of members of the genus Brucella to the genus and species level. Methods: We evaluated an in-house developed assay and various previously published real-time PCR assays targeting bcsp31 , per , IS711, alkB /IS711 and BMEI1162/IS711 using 248 Brucella strains representing the biotypes of all species and a large panel of clinically relevant, phylogenetically related and serologically cross-reacting bacteria. Results: No misidentification was observed. However, several biotypes of Brucella abortus and Brucella suis were not detected with some of the published assays. The limit of detection varied widely among the assays (16–1600 fg) demonstrating that some assays should not be applied to clinical samples but may help to identify colony material. Conclusions: In summary, most of the assays revealed low detection limits and proved to be highly selective for the detection of the genus Brucella and the species that are most relevant for humans. Assays targeting the bcsp31 gene can be recommended to screen for Brucella . Species-specific assays should be consecutively applied confirming the primary diagnosis by a second gene target. Clin Chem Lab Med 2007;45:1464–70.
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October 31, 2007
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Background : Resistin, a novel adipocyte-derived peptide, has been linked to inflammatory process and coronary artery disease (CAD). The –420C>G polymorphism located in the resistin gene ( RETN ) promoter has recently been suggested to play a potential role in proinflammatory conditions (e.g., atherogenesis). However, whether this polymorphism has any effect on the inflammatory process in patients with stable CAD is unclear. Methods : The RETN –420C>G polymorphism was determined by using PCR-restriction fragment length polymorphism. Plasma lipid profiles, glucose and high-sensitivity C-reactive protein (hs-CRP) were measured in fasting state. Results : Patients with variant genotypes (CG+GG) had significantly higher levels of hs-CRP than CC carriers (adjusted p<0.001). In addition, the variant genotypes were observed to be independently associated with higher hs-CRP levels (>3 mg/L, p=0.004). However, no association was found between this polymorphism and plasma lipids or glucose levels. Conclusion : Our data suggest that the RETN –420C-to-G variant is associated with increased CRP levels in patients with stable CAD, suggesting that the RETN –420C>G polymorphism may be potentially involved in the inflammatory component of atherogenesis through an enhanced production of CRP. Clin Chem Lab Med 2007;45:1471–5.
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October 31, 2007
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Background : Nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) mediates endothelium-dependent vasodilatation and antithrombotic action. Controversial results regarding the association of eNOS gene ( NOS3 ) polymorphisms with myocardial infarction (MI) have been reported. In the present study, we examined a possible association between a 27-base pair (bp) repeat polymorphism in intron 4 of the NOS3 gene and MI in a subgroup of the Tunisian population. Methods : A total of 310 Tunisian patients with MI and 250 healthy controls were included in the study. The NOS3 gene intron 4a4b variable number of tandem repeats polymorphism was analyzed by PCR. Results : A significant difference in genotype distribution and allele frequency was observed between patients and controls. Patients with MI had a frequency of 4.8% for the 4a4a genotype, 33.9% for the 4a4b genotype and 61.3% for the 4b4b genotype. Controls had a frequency of only 1.6% for the 4a4a genotype, 24.4% for the 4a4b genotype and 74.0% for the 4b4b genotype (χ 2 =11.81, p=0.003). The MI patient group showed a significant higher frequency of the 4a allele compared to controls (0.218 vs. 0.139; χ 2 =5.81, p=0.01). Conclusions : In the present study, a significant association between the NOS3 4a/4b gene polymorphism (presence of 4a allele) and MI in the Tunisian population was found. Clin Chem Lab Med 2007;45:1476–80.
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October 31, 2007
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Background : There is a certain difference in opinion regarding the optimal choice of housekeeping genes used as normalization factors in gene expression analysis. We have therefore examined the suitability of three housekeeping genes, hypoxanthine phosphoribosyl transferase, β-glucuronidase and β 2 -micro-globulin, for normalization of expression data from melanoma metastases. Methods : The expression of the three housekeeping genes was quantified by quantitative reverse transcription PCR in snap-frozen sections from 44 melanoma metastases, of which 19 were from patients treated with cisplatinum, dacarbazine and interferon-α2b. Results : The expression of each housekeeping gene varied considerably between the different metastases. Histopathological examination of the tissue sections revealed variation in the amount of tumor cells in the tissue, necrosis, varying degrees of lymphocyte infiltration, and lymph node remnants. Based on this examination, 16 biopsies were omitted from further analysis because they had cracked, contained empty or necrotic areas, or were dominated by lymph node tissue. Even in sections with more than 90% tumor cells, a wide variation in the expression of the three housekeeping genes was found. The amount of lymphatic infiltrate in the tumors can have an effect on the expression of housekeeping genes in the meta-stases, whereas treatment did not seem to influence the expression. Conclusions : We conclude that the choice of housekeeping genes can have great impact on the normalization of specific genes in melanoma metastases. Furthermore, in the analysis of mRNA expression in tumor tissue, microscopic examination is of great importance to evaluate the integrity and cellular composition of the biopsy. Clin Chem Lab Med 2007;45:1481–7.
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October 31, 2007
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Background: The clinical relevance of positive molecular staging as defined by reverse transcriptase-polymerase chain reaction (RT-PCR) detections of both prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) transcripts in the peripheral blood (PB) of patients with prostate cancer is still debatable. Methods: We analyzed the biochemical failure-free survival (bFFS) of prostate cancer patients with positive molecular staging who underwent immediate curative therapy (Group I, n=39) compared to prostate cancer patients who did convert their positive molecular staging by the administration of combined androgen blockade (CAB) for 12 months prior to curative treatment (Group II, n=15). Results: The median bFFS for Group I was 9 months (95% CI 5–13 months) and was significantly lower compared to Group II (>36 months, p<0.001). In Group I, the median time for PSA values of >2.0 ng/mL was 18 months (95% CI 12–21 months, range 12–36 months). Notably, only one patient from Group II reached PSA values >2.0 ng/mL at 36 months post-curative treatment. Conclusions: In patients with clinically localized prostate cancer and positive RT-PCR detection of PSA and PSMA transcripts in PB, CAB can convert positive molecular staging status to negative and by doing so it modifies the post-curative therapy bFFS of patients with clinically localized prostate cancer. Clin Chem Leb Med 2007;45:1488–94.
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October 31, 2007
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Isobutyryl-CoA dehydrogenase (IBD) is an enzyme involved in the catabolism of the branched-chain amino acid valine. IBD deficiency is a very rare metabolic disorder, whereby only a few cases have been reported thus far. Recently, we observed a Korean newborn boy with elevated concentration of C 4 -acylcarnitine detected by tandem mass spectrometry neonatal screening. Subsequent sequencing analysis of ACAD8 gene revealed that he was compound heterozygous for a novel mutation involving the first codon (c.3G>T; Met1Ile) and a previously reported mutation (c.1000C>T; Arg334Cys). To the best of our knowledge, this is the first confirmed case of IBD deficiency based on biochemical and genetic studies not only in Korea but also in Asia. Clin Chem Lab Med 2007;45:1495–7.
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October 31, 2007
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Background : Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of nuclear factor-κB ligand (RANKL). OPG and RANKL have been shown to be important regulators of osteoclastogenesis. The aim of this study was to investigate the relationship between the OPG-RANKL system and bone mineral metabolism in patients with chronic renal failure (CRF). Methods : Serum OPG, RANKL, osteocalcin, cross-linked c-telopeptide of type I collagen (ICTP), intact parathyroid hormone (PTH), bone alkaline phosphatase and cystatin C levels were measured in 40 chronic hemodialysis male patients and 32 age- and sex-matched healthy controls. Their lumbar spine bone mineral density (LS-BMD) was measured by dual energy X-ray absorptiometry. Results : Serum OPG, RANKL, PTH, bone alkaline phosphatase and cystatin C levels were significantly increased in patients with CRF. Serum OPG was positively correlated to serum RANKL and cystatin C. Positive correlations were found between serum RANKL and cystatin C and ICTP. LS-BMD was significantly lower in patients with CRF than in controls. In patients with CRF, LS-BMD was inversely correlated to serum RANKL and cystatin C, whereas it was positively correlated to serum OPG. Conclusions : The OPG-RANKL system is involved in the pathogenesis and regulation of bone turnover in CRF. Circulating levels of OPG and RANKL may be useful markers to assess turnover renal osteopathies. Clin Chem Lab Med 2007;45:1498–503.
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October 31, 2007
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Background : Decreased concentrations of the circulating angiogenic factors, free placental growth factor (PLGF) and free vascular endothelial growth factor (VEGF), and increased concentrations of the anti-angiogenic factor, soluble fms-like tyrosine kinase 1 (sFLT-1) have been observed during clinical preeclampsia. We established a new PLGF-ELISA kit for the measurement of PLGF in sera. In the present study, we demonstrated the assay characteristics by measurement of PLGF expression in normal and preeclamptic pregnancies as compared to an established research kit. Methods : Blood samples were taken from 64 women with singleton uncomplicated pregnancies for longitudinal measurement of PLGF in the course of pregnancy. In 30 preeclamptic patients, serum levels of PLGF and sFLT-1 were measured by Human PLGF-ELISA and Human sVEGF R1 ELISA according to the described test principles. The assay characteristics of the new PLGF-ELISA were determined and the results were compared to those performed with an available research kit. Results : The PLGF concentration in normal pregnancies showed a steady increase starting at the beginning of the second trimester with a peak at 28–32 weeks and a consistent decline thereafter. The preeclamptic pregnancies had significant lower serum concentrations of PLGF and significant higher serum concentrations of sFLT-1 as compared to the non-preeclamptic pregnancies. All the measured assay characteristics fulfilled the required specifications. Comparison of the values of the new PLGF-ELISA and the established research kit resulted in a correlation coefficient of 0.921. Conclusions : Our results support the hypothesis that an imbalance between factors promoting angiogenesis, such as PLGF, and factors antagonizing angiogenesis, such as sFLT-1, has a fundamental role in the pathogenesis of preeclampsia. The new established ELISA test can be considered reliable and it offers many advantages. As it is authorized for routine diagnostic testing, it may offer new possibilities in the prediction of preeclampsia in clinical routine. Clin Chem Lab Med 2007;45:1504–10.
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October 31, 2007
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Background : The aim of the present study was to investigate the effect of rosiglitazone, a peroxisome proliferator-activated receptor γ2 (PPAR-γ2) agonist, on the expression of β 3 -adrenergic receptor (β 3 -AR) at transcriptional and translational level. Methods : We cloned the cDNA sequences of human PPAR-γ2 (hPPAR-γ2) gene and human wild type and mutant β 3 -adrenergic receptor ( hβ 3 -AR ) genes and established their eukaryotic expression vectors. The pcDNA3.1/hβ 3 -AR (mutant and wild type) was transfected into SH-SY5Y cells using electroporation method. The expression level of β 3 -AR protein was determined by Western blot analysis. Results : Our results showed that the reverse transcription-PCR products were consistent with theoretical fragment sizes of human PPAR-γ2 (1544 bp) and human β 3 - AR genes (1578 bp). The sequence analysis of PPAR-γ2 and β 3 -AR genes showed that the fragment sizes were the same as that of human PPAR-γ2 and human β 3 - AR genes in Genebank. The pcDNA3.1/hβ 3 -AR (mutant and wild type) was successfully cloned to SH-SY5Y cells. We found that the expression of β 3 -AR protein was significantly inhibited by rosiglitazone in a concentration-dependent manner in SH-SY5Y cell lines stably expressed β 3 - AR genes. Conclusions : The results suggest that rosiglitazone has a concentration-dependent inhibitory effect on the expression of β 3 -AR protein, and this inhibitory effect may be due to activation of PPAR-γ2 receptor. Clin Chem Lab Med 2007;45:1511–6.
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October 31, 2007
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Background : The aim of this study was to evaluate the biochemical composition and cytological examination of 25 thyroid cyst fluid specimens that were obtained by fine needle aspiration, and to compare results according to gender and color of cyst fluid. We anticipated that measuring biochemical routine parameters in cyst fluid would contribute to the pathophysiology of thyroid nodule formation leading to better clinical outcomes when compared to therapies based only on cytological examination. Methods : We analyzed 23 parameters in serum and cyst fluid samples taken from 25 euthyroid patients. In addition, cytological examination of cyst fluids was performed. Results : We revealed that mean levels of glucose, phosphorus, high-density lipoprotein cholesterol, antibodies to thyroglobulin, and activities of alanine aminotransferase and alkaline phosphatase were lower, and mean levels of uric acid, free triiodothyronine, free thyroxine, and thyroglobulin and activity of lactate dehydrogenase in the cyst fluid of thyroid nodules were higher when compared to their own serum sample levels. Also, there were significant differences according to gender and color of cyst fluid. Conclusions : Biochemical examination of thyroid cyst fluid may be of value for the clinician to evaluate the nature of thyroid nodules. The potential benefits of thyroid cyst fluid examination warrant further investigation in patients with thyroid nodules. Clin Chem Lab Med 2007;45:1517–22.
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October 31, 2007
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Circulating thyroglobulin (Tg) measurement after thyrotropin stimulation is a pivotal tool in the management of patients affected by differentiated thyroid carcinoma. The Tg assay on Immulite platform has a declared functional sensitivity of 0.9 ng/mL and it is widely used in clinical practice and research on thyroid carcinoma. Recently, thyroglobulin measured during thyroxine treatment was found to be adequate for thyroid carcinoma follow-up if functional sensitivity at 0.2–0.3 ng/mL was reached by assay methods. Thus, the present study was then undertaken to evaluate the imprecision of Immulite Tg assay at very low concentrations. The detection limit was calculated on zero calibrator and Tg-free pooled sera replicates and was 0.14 and 0.16 ng/mL, respectively. Different serum pools with Tg concentrations ranging from 0.16 to 2.50 ng/mL were assayed according to the National Academy of Clinical Biochemistry guidelines to estimate functional sensitivity. By interpolating the imprecision profile with a coefficient of variation of 20%, the functional sensitivity was 0.36 ng/mL. The Immulite-Tg assay was directly compared with a high-sensitive immunoradiometric Tg assay in sera from 93 patients with thyroid carcinomas. No significant differences in sensitivity and specificity were observed by using the newly defined functional sensitivity. In conclusion, the Immulite Tg assay showed a lower functional sensitivity than expected and performed comparably to high-sensitive immunoradiometric assay in patients with thyroid carcinoma. Clin Chem Lab Med 2007;45:1523–4.
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October 31, 2007
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Background : The L-arginine/nitric oxide (NO) pathway has multiple physiological functions including vasodilation, inhibition of platelet aggregation and neurotransmission. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of all known NO synthase isoforms, has adverse effects on renal and cardiovascular function in adults. It is unknown whether ADMA might also exert similar effects in younger individuals including infants. Also, reference data for important members of the L-arginine/NO family, notably ADMA and the NO metabolites, nitrite and nitrate, in infancy are lacking. Methods : In the present study, we investigated the status of the L-arginine/NO pathway in 34 healthy volunteers aged 2 days to 24 years by measuring the concentration of ADMA, nitrite, nitrate and L-arginine in plasma and urine using gas chromatography-mass spectrometry and gas chromatography-tandem mass spectrometry methods. Results : We found that ADMA levels in plasma decreased with age (Pearson correlation coefficient r=–0.619, p<0.001). In contrast, urinary excretion of nitrate (r=0.471, p=0.036) and nitrite increased with age (r=0.484, p=0.037). Conclusions : Our study suggests that in infants ADMA biosynthesis accompanied by an inhibition of NO synthesis is higher than in adults and diminishes considerably with age. Clin Chem Lab Med 2007;45:1525–30.
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October 31, 2007
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Background: Neonatal infection remains a major diagnostic problem because of non-specific clinical signs and symptoms, as well as low sensitivity and specificity of routine laboratory tests. C-reactive protein (CRP), white blood cell count, absolute neutrophil count and immature/total neutrophil ratio are the most widely used tests in the diagnosis of sepsis and provide useful information, but none of these has demonstrated to be reliable in detecting all septic infants. Procalcitonin (PCT) has been suggested as a potentially useful laboratory test performed in umbilical cord blood when perinatal bacterial sepsis is under investigation. Methods: In this study, the reference interval for umbilical cord blood serum PCT was established for the first time by Time-Resolved Amplified Cryptate Emission (TRACE) technology. Results: The reference interval for PCT in umbilical cord blood serum ranged from 0.04 to 0.43 μg/L in 168 non-infected newborn infants (95% CI 0.02–0.06 and 0.35–0.60 μg/L, respectively). Cord blood serum PCT correctly classified one infected patient out of 90 newborn infants at risk of vertically transmitted sepsis and identified another neonate as a potentially infected patient despite having negative blood cultures. However, cord blood CRP misclassified 21 out of the 90 patients as infected neonates. Conclusions: Cord blood PCT measured by TRACE is a potentially more useful early marker of neonatal sepsis than cord blood CRP. Clin Chem Lab Med 2007;45:1531–5.
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October 31, 2007
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Background : Point-of-care testing for creatinine blood concentrations may be useful in predicting the onset of recurrent conditions threatening renal function in children at home. Our aim was to evaluate two point-of-care systems for creatinine testing vs. an automated creatinine assay. Methods : Twenty patients aged between 2 months and 17 years were randomly selected. Capillary blood specimens were taken for two point-of-care tests (Reflotron and i-STAT), and the results were compared to the routine enzymatic creatinine assay on a Hitachi 912 analyser using material collected simultaneously. Results : The mean difference in creatinine concentration between the Reflotron and the Hitachi 912 and i-STAT and Hitachi 912 test was –16 and 4 μmol/L, respectively. The slope of the Passing-Bablok method comparison was 0.95 (95% CI 0.87–1.06) and 0.96 (95% CI 0.90–1.00) for the Reflotron and i-STAT test, respectively. Conclusions : The blood creatinine concentrations measured using the Reflotron and the i-STAT device correlated well with those from the routine assay, especially in the concentration range up to 500 μmol/L. Both systems are good options for point-of-care creatinine testing in capillary blood. However, the i-STAT seems the better option for monitoring at home given its greater ease of use. Clin Chem Lab Med 2007;45:1536–41.
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October 31, 2007
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Background : Closure time measured by a platelet function analyser (PFA-100 ® ) was examined for its usefulness in assessing the efficacy of platelet membrane glycoprotein IIb/IIIa antagonists in vitro, and was compared to optical platelet aggregometry. Methods : Three known glycoprotein IIb/IIIa antagonists [H-Arg-Gly-Asp-Ser-OH (RGDS), tirofiban and eptifibatide] and six new peptidomimetic glycoprotein IIb/IIIa antagonists (DKT-59, DPS-172, SMA-101, SMA-104, SMA-179 and SKN-191) were assessed. The concentration of antagonist which doubled closure time in collagen/ADP and collagen/epinephrine cartridges (IC 200 ) or decreased ADP- or collagen-induced platelet aggregation by 50% (IC 50 ) was used to assess the efficacy of the glycoprotein IIb/IIIa antagonist in inhibiting platelet function. Results : IC 200 for collagen/ADP and collagen/epinephrine closure times and IC 50 for ADP- and collagen-induced platelet aggregation were highly associated (correlation coefficients 0.97–1.00, all p<0.001). Therefore, according to both methods, the most efficient glycoprotein IIb/IIIa antagonist was tirofiban (IC 200 =0.030–0.034 μmol/L, IC 50 =0.005–0.027 μmol/L) and the least efficient was RGDS (IC 200 =875–1100 μmol/L, IC 50 =124–377 μmol/L; all data are means), while the new peptidomimetic glycoprotein IIb/IIIa antagonists exhibited intermediate efficacies. Conclusions : Closure time represents a fast, simple and sensitive method of assessing glycoprotein IIb/IIIa antagonism in vitro, is comparable to optical aggregometry, and suitable for testing larger numbers of glycoprotein IIb/IIIa antagonists. Clin Chem Lab Med 2007;45:1542–8.
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October 31, 2007
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Background: Rapid and reliable bed-side determination of blood glucose concentration is very important in the management of acutely ill infants and especially in premature newborns. HemoCue is an easy-to-use glucose analyser. The aim of the present study was to examine the usefulness of the HemoCue glucose analyser compared to a reference plasma glucose method (SYS, BM/Hitachi 747/737) in a neonatal intensive care unit (NICU). Methods: Seventy-eight consecutive neonates admitted to our NICU were enrolled in the study. At the time of the study all patients were grouped according to nutritional management (parenteral or enteral nutrition), haematocrit values and birth weight. The effects of feeding management, haematocrit values, and birth weight on accuracy and precision of the device were evaluated. Results: Overall data linear regression analysis yielded an r-value of 0.905 and the Bland-Altman method demonstrated that HemoCue overestimates plasma glucose by 0.932 mmol/L. Evaluation of our data by receiver operating characteristic curve demonstrated 100% sensitivity cutoff at 4.1 mmol/L. Conclusions: HemoCue cannot be used satisfactorily in the management of glycaemia in the NICU. In the preterm population, birth weight had a dramatic influence on HemoCue accuracy. Low haematocrit and parenteral feeding further contributed to a decrease in the accuracy of this device. Clin Chem Lab Med 2007;45:1549–54.
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November 1, 2007
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Background : Carbohydrate-deficient transferrin (CDT) is a biochemical marker used for identifying chronic alcohol intake. We developed and validated an ARCHITECT c 8000 ® (Abbott) instrument application for the Axis-Shield %CDT immunoassay. Methods : Standard CLSI (Clinical and Laboratory Standards Institute) evaluation protocols were performed. Results : The Axis-Shield %CDT ARCHITECT ® method was standardized against the Axis-Shield %CDT microtiter test by linear regression analysis (n=50 mean of duplicate, R=0.996). Method comparison by Deming regression revealed a slope of 1.01 and an intercept of –0.03 with Axis-Shield %CDT microtiter test (n=50 in duplicate, R=0.995), and a slope of 0.82 and an intercept of 1.09 with HPLC method (n=47 in duplicate, R=0.990) as the candidate IFCC (International Federation of Clinical Chemistry and Laboratory Medicine) reference method. The predicted medical decision points (MDPs) are both 2.6% and equal the MDP that is generally used for the Axis-Shield %CDT tests. Precision derived from pooled patient sera (low level) and commercially available control material (high level) was excellent. Total variation was 3.2% and 1.8%, respectively. Conclusions : The Axis-Shield %CDT ARCHITECT ® method, as one of the first Axis-Shield applications on a large-scale analyzer, is a reliable test for routine %CDT analysis providing precise and well-standardized %CDT results. Clin Chem Lab Med 2007;45:1555–8.
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November 1, 2007
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October 31, 2007
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