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  • 1. Apweiler, Rolf
    et al.
    Aslanidis, Charalampos
    Deufel, Thomas
    Gerstner, Andreas
    Hansen, Jens
    Hochstrasser, Dennis
    Kellner, Roland
    Kubicek, Markus
    Lottspeich, Friedrich
    Maser, Edmund
    Mewes, Hans-Werner
    Meyer, Helmut E.
    Müllner, Stefan
    Mutter, Wolfgang
    Neumaier, Michael
    Nollau, Peter
    Nothwang, Hans G.
    Pontén, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Genetics and Pathology.
    Radbruch, Andreas
    Reinert, Knut
    Rothe, Gregor
    Stockinger, Hannes
    Tarnok, Attila
    Taussig, Mike J.
    Thiel, Andreas
    Thiery, Joachim
    Ueffing, Marius
    Valet, Günther
    Vandekerckhove, Joel
    Verhuven, Wiltrud
    Wagener, Christoph
    Wagner, Oswald
    Schmitz, Gerd
    Approaching clinical proteomics: current state and future fields of application in fluid proteomics2009In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 47, no 6, p. 724-744Article, review/survey (Refereed)
    Abstract [en]

    The field of clinical proteomics offers opportunities to identify new disease biomarkers in body fluids, cells and tissues. These biomarkers can be used in clinical applications for diagnosis, stratification of patients for specific treatment, or therapy monitoring. New protein array formats and improved spectrometry technologies have brought these analyses to a level with potential for use in clinical diagnostics. The nature of the human body fluid proteome with its large dynamic range of protein concentrations presents problems with quantitation. The extreme complexity of the proteome in body fluids presents enormous challenges and requires the establishment of standard operating procedures for handling of specimens, increasing sensitivity for detection and bioinformatical tools for distribution of proteomic data into the public domain. From studies of in vitro diagnostics, especially in clinical chemistry, it is evident that most errors occur in the preanalytical phase and during implementation of the diagnostic strategy. This is also true for clinical proteomics, and especially for fluid proteomics because of the multiple pretreatment processes. These processes include depletion of high-abundance proteins from plasma or enrichment processes for urine where biological variation or differences in proteolytic activities in the sample along with preanalytical variables such as inter- and intra-assay variability will likely influence the results of proteomics studies. However, before proteomic analysis can be introduced at a broader level into the clinical setting, standardization of the preanalytical phase including patient preparation, sample collection, sample preparation, sample storage, measurement and data analysis needs to be improved. In this review, we discuss the recent technological advances and applications that fulfil the criteria for clinical proteomics, with the focus on fluid proteomics. These advances relate to preanalytical factors, analytical standardization and quality-control measures required for effective implementation into routine laboratory testing in order to generate clinically useful information. With new disease biomarker candidates, it will be crucial to design and perform clinical studies that can identify novel diagnostic strategies based on these techniques, and to validate their impact on clinical decision-making.

  • 2. Björk, Jonas
    et al.
    Grubb, Anders
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Hansson, Lars-Olof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Flodin, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Sterner, Gunnar
    Lindström, Veronica
    Nyman, Ulf
    Accuracy of GFR estimating equations combining standardized cystatin C and creatinine assays: a cross-sectional study in Sweden2015In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 53, no 3, p. 403-414Article in journal (Refereed)
    Abstract [en]

     Background: The recently established international cystatin C calibrator makes it possible to develop non-laboratory specific glomerular filtration rate (GFR) estimating (eGFR) equations. This study compares the performance of the arithmetic mean of the revised Lund-Malmö creatinine and CAPA cystatin C equations (MEANLM-REV+CAPA), the arithmetic mean of the Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI) creatinine and cystatin C equations (MEANCKD-EPI), and the composite CKD-EPI equation (CKD-EPICREA+CYSC) with the corresponding single marker equations using internationally standardized calibrators for both cystatin C and creatinine.

    Methods: The study included 1200 examinations in 1112 adult Swedish patients referred for measurement of GFR (mGFR) 2008-2010 by plasma clearance of iohexol (median 51 mL/min/1.73 m2). Bias, precision (interquartile range, IQR) and accuracy (percentage of estimates ±30% of mGFR; P30) were compared.

    Results: Combined marker equations were unbiased and had higher precision and accuracy than single marker equations. Overall results of MEANLM-REV+CAPA/MEANCKD-EPI/CKD-EPICREA+CYSC were: median bias -2.2%/-0.5%/-1.6%, IQR 9.2/9.2/8.8 mL/min/1.73 m2, and P30 91.3%/91.0%/91.1%. The P30 figures were about 7-14 percentage points higher than the single marker equations. The combined equations also had a more stable performance across mGFR, age and BMI intervals, generally with P30 ≥90% and never <80%. Combined equations reached P30 of 95% when the difference between eGFRCREA and eGFRCYSC was <10% but decreased to 82% at a difference of ≥40%.

    Conclusions: Combining cystatin C and creatinine assays improves GFR estimations with P30 ≥90% in adults. Reporting estimates of both single and combined marker equations in clinical settings makes it possible to assess the validity of the combined equation based on the agreement between the single marker equations.

  • 3. Börjel, Anna K.
    et al.
    Yngve, Agneta
    Karolinska Inst, Huddinge, Sweden.
    Sjöström, Michael
    Nilsson, Torbjörn K.
    Novel mutations in the 5'-UTR of the FOLR1 gene2006In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 44, no 2, p. 161-167Article in journal (Refereed)
    Abstract [en]

    We have previously reported two novel mutations in the 5'-untranslated region (UTR) of the gene for folate receptor-alpha (FOLR1). In our search for additional mutations, 92 patient samples with elevated levels of homocysteine were screened by single-strand conformation polymorphism (SSCP) between nt -425 and -782, and -712 and -1110. Between nt -425 and -782 we did not find any mutations. Between nt -712 and -1110 there were three novel mutations. One subject had two mutations very close to each other, c.-856C>T and c.-921T>C. Two subjects had a c.-1043G>A mutation. To get an idea of the prevalence of FOLR1 mutations in an unselected population, we also screened 692 healthy school children for mutations. In this cohort, between nt -188 and +272 we discovered one novel mutation, a single nucleotide substitution, c.-18C>T, in addition to five children with the 25-bp deletion mutation previously described by us. Thus, so far we have discovered six novel mutations in the 5'-UTR region of the gene for folate receptor-alpha. We genotyped all 17 subjects with a FOLR1 mutation for the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism, and developed new single-nucleotide polymorphism (SNP) genotyping protocols for MTHFR 1298A>C and 1793G>A utilising Pyrosequencing technology. None of the 17 subjects had the 677TT genotype, which ruled out this as a cause of elevated homocysteine levels, which was observed in some of the subjects. Further studies of mutations in the 5'-UTR of FOLR1, and in particular of their interplay with folate intake status, are warranted.

  • 4.
    Falorni, Alberto
    et al.
    Univ Perugia, Dept Med, I-06126 Perugia, Italy..
    Bini, Vittorio
    Univ Perugia, Dept Med, I-06126 Perugia, Italy..
    Betterle, Corrado
    Univ Padua, Dept Med, Endocrine Unit, Padua, Italy..
    Brozzetti, Annalisa
    Univ Perugia, Dept Med, I-06126 Perugia, Italy..
    Castano, Luis
    Univ Basque Country, Cruces Univ Hosp, Ciberdem, BioCruces, Bilbao, Spain..
    Fichna, Marta
    Poznan Univ Med Sci, Dept Endocrinol & Metab, Poznan, Poland.;Polish Acad Sci, Inst Human Genet, PL-60479 Poznan, Poland..
    Kämpe, Olle
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Autoimmunity. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Mellgren, Gunnar
    Haukeland Hosp, Hormone Lab, N-5021 Bergen, Norway.;Univ Bergen, Dept Clin Sci, Bergen, Norway..
    Peterson, Pärt
    Univ Tartu, Inst Biomed & Translat Med, Mol Pathol, EE-50090 Tartu, Estonia..
    Chen, Shu
    RSR Ltd, FIRS Labs, Cardiff, S Glam, Wales..
    Rönnelid, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Clinical Immunology.
    Seissler, Jochen
    Klinikum Univ Munchen, Med Klin & Poliklin 4, Diabet Zentrum, Munich, Germany..
    Tiberti, Claudio
    Univ Roma La Sapienza, Dept Expt Med, I-00185 Rome, Italy..
    Uibo, Raivo
    Univ Tartu, Inst Biomed & Translat Med, Dept Immunol, EE-50090 Tartu, Estonia..
    Yu, Liping
    Univ Colorado Denver, Barbara Davis Ctr Diabet, Aurora, CO USA..
    Lernmark, Åke
    Lund Univ, Skane Univ Hosp, Dept Clin Sci, Malmo, Sweden..
    Husebye, Eystein
    Univ Bergen, Dept Clin Sci, Bergen, Norway.;Haukeland Hosp, Dept Med, N-5021 Bergen, Norway..
    Determination of 21-hydroxylase autoantibodies: inter-laboratory concordance in the Euradrenal International Serum Exchange Program2015In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 53, no 11, p. 1761-1770Article in journal (Refereed)
    Abstract [en]

    Background: 21-Hydroxylase autoantibodies (21OHAb) are markers of an adrenal autoimmune process that identifies individuals with autoimmune Addison's disease (AAD). Quality and inter-laboratory agreement of various 21OHAb tests are incompletely known. The objective of the study was to determine inter-laboratory concordance for 21OHAb determinations. Methods: Sixty-nine sera from 51 patients with AAD and 51 sera from 51 healthy subjects were blindly coded by a randomization center and distributed to 14 laboratories that determined 21OHAb, either by an "in-house" assay (n=9) using in vitro-translated S-35-21OH or luciferase-labeled 21OH or a commercial kit with I-125-21OH (n=5). Main outcome measures were diagnostic accuracy of each participating laboratory and inter-laboratory agreement of 21OHAb assays. Results: Intra-assay coefficient of variation ranged from 2.6% to 5.3% for laboratories using the commercial kit and from 5.1% to 23% for laboratories using "in-house" assays. Diagnostic accuracy, expressed as area under ROC curve (AUC), varied from 0.625 to 0.947 with the commercial kit and from 0.562 to 0.978 with "in-house" methods. Cohen's. of inter-rater agreement was 0.603 among all 14 laboratories, 0.691 among "in-house" laboratories, and 0.502 among commercial kit users. Optimized cutoff levels, calculated on the basis of AUCs, increased the diagnostic accuracy of every laboratory (AUC >0.9 for 11/14 laboratories) and increased the Cohen's. of inter-rater agreement. Discrepancies in quantitation of 21OHAb levels among different laboratories increased with increasing autoantibody levels. Conclusions: The quality of 21OHAb analytical procedures is mainly influenced by selection of cutoff value and correct handling of assay materials. A standardization program is needed to identify common standard sera and common measuring units.

  • 5.
    Flodin, Mats
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Hansson, Lars-Olof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Variations in assay protocol for the Dako cystatin C method may change patient results by 50% without changing the results for controls2006In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 44, no 12, p. 1481-1485Article in journal (Refereed)
    Abstract [en]

    Background: Cystatin C is increasingly used as a glomerular filtration marker, but so far only a few companies produce most of the cystatin C reagents suited for turbidimetry or nephelometry use in clinical laboratories. Methods: We studied different protocols for measuring cystatin C on an Architect ci8200 system using cystatin C reagents from Dako (Glostrup, Denmark). The results were compared with those obtained with Dade Behring reagents (Deerfield, IL, USA) on a BN ProSpec system. Results: Differences in assay protocol on the same instrument with the Dako reagent yielded an up to 50% difference in glomerular filtration rate calculated from the cystatin C results when analyzing patient samples, but had no effect on the results for controls. There were also significant differences regarding linearity and kinetics between samples and controls/calibrators. Conclusions: The results indicate different reactivity of the Dako antibodies against calibrators and controls in comparison with patient samples, highlighting the importance of using controls and calibrators that do not differ from patient samples.

  • 6.
    Hansson, Lars-Olof
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Flodin, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Althaus, Harald
    Blirup-Jensen, Sören
    Grubb, Anders
    The first harmonization step on cystatin C, with the aim to introduce the first ERM-DA471/IFCC cystatin C calibrator and one worldwide company-independent EGFR equation2011In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 49, no s1, p. s557-s557Article in journal (Refereed)
  • 7.
    Helmersson-Karlqvist, Johanna
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Åkerfeldt, Torbjörn
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Gunningberg, Lena
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Caring Sciences.
    Leo Swenne, Christine
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Caring Sciences.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Serum MMP-9 and TIMP-1 concentrations and MMP-9 activity during surgery-induced inflammation in humans2012In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 50, no 6, p. 1115-1119Article in journal (Refereed)
    Abstract [en]

     Background: Matrix metalloproteinase 9 (MMP-9) and the endogenous inhibitor to MMP-9, tissue inhibitor of metalloproteinase 1 (TIMP-1), have important roles in tissue remodelling and are implicated in a number of diseases related to inflammation. The time course in activation and formation of MMPs and TIMPs during an inflammatory reaction is not fully known. This study investigates MMP-9 and TIMP-1 concentrations and MMP-9 activity at different time points after major surgery when a state of noticeable inflammation is expected.

    Methods: Serum MMP-9 and TIMP-1 concentrations and MMP-9 activity were analysed preoperatively and 4 and 30 days postoperatively in patients undergoing elective surgery (coronary artery bypass n=21; orthopaedic surgery, n=29).

    Results: Serum TIMP-1 and MMP-9 activity increased significantly 4 days after surgery (p<0.05 and p<0.01, respectively) and decreased again 30 days after surgery (p<0.01, respectively, compared to 4 days after surgery). Serum MMP-9 increased significantly 4 days after surgery (p<0.05) and was still high 30 days after surgery (p<0.01 compared to before surgery). The calculated MMP-9/TIMP-1 ratio was increased 30 days after surgery compared to before surgery (p<0.01).

    Conclusions: The inflammatory state induced by elective surgery is associated with increased TIMP-1 response and MMP-9 activity in serum within a few days which may be of importance for the postoperative heeling process. The further increase in MMP-9 concentrations at day 30 postoperative did not result in increased MMP-9 activity. Serum MMP-9 concentrations or the calculated MMP-9/TIMP-1 ratio do not entirely represent MMP-9 activity during surgery-induced inflammation.

  • 8.
    Lindahl, Bertil
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology.
    Acute coronary syndrome: the present and future role of biomarkers2013In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 51, no 9, p. 1699-1706Article, review/survey (Refereed)
    Abstract [en]

    Over the past two decades there have been dramatic changes in the diagnosis, treatment and prognosis of acute coronary syndrome (ACS). Several new treatment modalities have been added and the prognosis has improved dramatically. Biomarkers play a crucial role in the management of ACS. At present, cardiac troponin is the biomarker of choice for diagnosis of acute myocardial infarction (AMI). Currently, there are no other biomarkers, which can compete, neither regarding specificity nor regarding early sensitivity. However, there is still a clinical need of a biomarker able to reliably rule-in or rule-out AMI immediately on admission. MicroRNAs seem to be promising new candidates for diagnostic purposes. The optimal combination of biomarkers and new imaging techniques is another important area for research. The list of biomarkers associated with an adverse prognosis in ACS is long. However, for most of them it has been very difficult to prove an added clinical value. Only cardiac troponin, and to some degree also B-type natriuretic peptides, is widely used in clinical practice for risk assessment. Among new markers, growth differentiation factor 15 and the mid-regional part of the prohormone of adrenomedullin, have shown some promising results. Since the renal function is assessed in clinical routine, also markers of the renal function have gained increasing interest. Cardiac troponin has been proven useful for selection of antithrombotic, antiplatelet and invasive treatment. Besides cardiac troponin, no other markers have consistently been shown to be useful for selection of specific treatments.

  • 9.
    Lindahl, Bertil
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology.
    Eggers, Kai M
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center.
    Venge, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    James, Stefan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center.
    Evaluation of four sensitive troponin assays for risk assessment in acute coronary syndromes using a new clinically oriented approach for comparison of assays2013In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 51, no 9, p. 1859-1864Article in journal (Refereed)
    Abstract [en]

    Background:

    Measurement of cardiac troponin T or I (cTnT; cTnI) is useful for risk prediction in acute coronary syndromes. The objective of the present study was to compare the prognostic capacity of four sensitive cardiac troponin assays using a new method for comparison.

    Methods:

    Cardiac troponin was analyzed in serum samples from 1335 patients with acute coronary syndrome using the Elecsys high sensitivity TnT (hs-cTnT), ARCHITECT STAT high sensitivity TnI (hs-cTnI), Access AccuTnI (Acc-cTnI) and Architect cTnI (Arc-cTnI) assays. All patients were followed for 30 days regarding death and acute myocardial infarction (AMI), and for 1 year regarding mortality.

    Results:

    By receiver operating characteristic (ROC) curve analyses, there were only minor differences in the area under the curves (AUC) between the assays. At a given sensitivity of 85% the hs-cTnT, Arc-cTnI and Acc-cTnI assays showed comparable specificities, while 90% or higher sensitivity was only possible to achieve with the hs-cTnT, hs-cTnI and Acc-cTnI assays. The highest odds ratios for death/AMI at 30 days and death at 1 year, respectively, were reached by cut-off levels yielding 95% sensitivity; these cut-off levels were below the respective 99th percentile levels.

    Conclusions:

    By the adoption of a new method for the comparison of cardiac troponin assays we showed that the hs-cTnT, hs-cTnI and Acc-cTnI assays had comparable prognostic properties, while the Arc-cTnI assay had inferior prognostic sensitivity.

  • 10. Nisman, Benjamin
    et al.
    Allweis, Tanir
    Kadouri, Luna
    Mali, Bela
    Hamburger, Tamar
    Baras, Mario
    Gronowitz, Simon
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Microbiology and Infectious Medicine, Clinical Virology.
    Peretz, Tamar
    Comparison of diagnostic and prognostic performance of two assays measuring thymidine kinase 1 activity in serum of breast cancer patients2013In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 51, no 2, p. 439-447Article in journal (Refereed)
    Abstract [en]

    Background: We compared two recently developed immuno assays for serum thymidine kinase 1 (TK1) activity: one manual assay (DiviTum, Biovica (R)) and one fully automated assay (Liaison, Diasorin (R)). Methods: The study included 368 women: 149 healthy blood donors (control), 59 patients with benign breast disease (BBD) and 160 patients with primary breast cancer (BC). Results: A regression analysis of the Liaison (y) and DiviTum (x) assays for all three groups yielded the equation y=3.93+0.03x (r=0.85, n=368). The r-value in BC was higher than in control and BBD (0.90 vs. 0.81 and 0.64). The correlation between the two assays for TK1 values above the cut-off was higher compared to that below (0.88 and 0.59). Breakdown of the BBD group into subgroups with proliferative and non-proliferative lesions was effective only with the measurement of TK1 with DiviTum assay (p=0.03). The TK1 activity determined preoperatively in BC patients with DiviTum and Liaison assays was significantly associated with T-stage (for both p=0.01), presence of vascular invasion (p=0.002 and p=0.02), lack of estrogen receptor (ER) (p=0.001 and p=0.01) and progesterone receptor (PR) (p=0.01 and p=0.03) expression. Only TK1 analyzed with the DiviTum assay was associated with tumor grade and molecular subtype of BC (p=0.02 and p=0.003). Multivariate Cox proportional hazards analyses demonstrated that T-stage, PR status and TK1 activity measured by both methods (DiviTum, RR=3.0, p=0.02 and Liaison, RR=3.1, p=0.01) were independent predictors of disease recurrence. Conclusions: In spite of differences observed between TK1 activity measured by the DiviTum and Liaison assays, both of them may be used for recurrence prediction in preoperative evaluation of BC patients.

  • 11. Nyman, Ulf
    et al.
    Grubb, Anders
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Hansson, Lars-Olof
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Flodin, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Nordin, Gunnar
    Equalis, Uppsala, Sweden.
    Lindström, Veronica
    Björk, Jonas
    The revised Lund-Malmö GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population2014In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 52, no 6, p. 815-824Article in journal (Refereed)
    Abstract [en]

     Background:

    The performance of creatinine-based glomerular filtration rate (GFR) estimating equations may vary in subgroups defined by GFR, age and body mass index (BMI). This study compares the performance of the Modification of Diet in Renal Disease (MDRD) study and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations with the revised Lund-Malmö equation (LM Revised), a new equation that can be expected to handle changes in GFR across the life span more accurately.

    Methods:

    The study included 3495 examinations in 2847 adult Swedish patients referred for measurement of GFR (mGFR) 2008-2010 by plasma clearance of iohexol (median 52 mL/min/1.73 m2). Bias, precision [interquartile range (IQR)] and accuracy [percentage of estimates ±10% (P10) and ±30% (P30) of mGFR] were compared.

    Results:

    The overall results of LM Revised/MDRD/CKD-EPI were: median bias 2%/8%/11%, IQR 12/14/14 mL/min/1.73 m2, P10 40%/35%/35% and P30 84%/75%/76%. LM Revised was the most stable equation in terms of bias, precision and accuracy across mGFR, age and BMI intervals irrespective of gender. MDRD and CKD-EPI overestimated mGFR in patients with decreased kidney function, young adults and elderly. All three equations overestimated mGFR and had low accuracy in patients with BMI <20 kg/m2, most pronounced among men.

    Conclusions:

    In settings similar to the investigated cohort LM Revised should be preferred to MDRD and CKD-EPI due to its higher accuracy and more stable performance across GFR, age and BMI intervals.

  • 12.
    Ridefelt, Peter
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Aldrimer, Mattias
    Rodoo, Per-Olof
    Niklasson, Frank
    Jansson, Leif
    Gustafsson, Jan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Pediatrics.
    Hellberg, Dan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Obstetrics and Gynaecology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Center for Clinical Research Dalarna.
    Population-based pediatric reference intervals for general clinical chemistry analytes on the Abbott Architect ci8200 instrument2012In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 50, no 5, p. 845-851Article in journal (Refereed)
    Abstract [en]

    Background: Reference intervals are crucial decision-making tools aiding clinicians in differentiating between healthy and diseased populations. However, for children such values often are lacking or incomplete.

    Methods: Blood samples were obtained from 692 healthy children, aged 6 months to 18 years, recruited in daycare centers and schools. Twelve common general clinical chemistry analytes were measured on the Abbott Architect ci8200 platform; sodium, potassium, chloride, calcium, albumin-adjusted calcium, phosphate, magnesium, creatinine (Jaffe and enzymatic), cystatin C, urea and uric acid.

    Results: Age- and gender specific pediatric reference intervals were defined by calculating the 2.5th and 97.5th percentiles.

    Conclusions: The data generated is primarily applicable to a Caucasian population when using the Abbott Architect platform, but could be used by any laboratory if validated for the local patient population.

  • 13.
    Ridefelt, Peter
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Axelsson, John
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Diurnal variability of total calcium during normal sleep and after an acute shift of sleep2012In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 50, no 1, p. 147-151Article in journal (Refereed)
    Abstract [en]

    Background: Serum total calcium is becoming a widely used test when screening for hyperparathyroidism (HPT) and other causes of hypercalcemia, even if serum calcium is tightly regulated in the body it is unclear whether the reference values are correct for tests taken at different times of the day or for individuals with altered sleep patterns. Thus, the aim was to investigate how timing of testing and sleep affects serum calcium.

    Methods: The diurnal variation of total calcium in serum during night-time and day-time conditions was studied in seven healthy volunteers. Serum samples for calcium measurements were collected every hour (48 samples per individual) to evaluate the effect of sampling times, sleep and food intake on the test results.

    Results: The median intra-individual coefficients of variations for calcium were 3.3% during night-time sleep and 2.8% during day-time sleep conditions. There was a clear diurnal variation in serum calcium, with a trough at 08.00 h in the morning after night-time sleep and a difference of approximately 0.07 mmol/L between trough and peak. Calcium was lower around the end of the sleep periods, for both night-time and day-time sleep. Food intake did not affect calcium concentrations.

    Conclusions: Evaluation of serum calcium results should take diurnal variation into account and allow slightly higher calcium values in the afternoon in comparison with samples collected in the morning.

  • 14. Savukoski, Tanja
    et al.
    Jacobino, Jenna
    Laitinen, Paivi
    Lindahl, Bertil
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, UCR-Uppsala Clinical Research Center.
    Venge, Per
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Biochemial structure and function.
    Ristiniemi, Noora
    Wittfooth, Saara
    Pettersson, Kim
    Novel sensitive cardiac troponin I immunoassay free from troponin I-specific autoantibody interference2014In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 52, no 7, p. 1041-1048Article in journal (Refereed)
    Abstract [en]

    Background: Cardiac troponins (cTnI and cTnT) are the recommended biomarkers of myocardial infarction. As cTn-specific autoantibodies (cTnAAb) can interfere with the cTn detection by state-of-the-art cTnI assays, our objective was to develop a sensitive cTnI immunoassay free from this analytical interference. Methods: The assay used antibody-coated spots containing three capture Mabs/Fabs directed against the N-terminus, midfragment and C-terminus of cTnI and a europium chelate-labeled tracer Mab against the C-terminus. Following a 3-h sample incubation and washing, cTnI was quantified by time-resolved fluorometry. Results: The limit of detection (LoD) was 2.9 ng/L and the assay was linear up to 50,000 ng/L. The total precision of 10% CV was not reached, but 20% CV was reached at 10 ng/L. Mean cTnI (10-50,000 ng/L) recoveries were 100% and 119% in three cTnAAb-positive and two cTnAAb-negative individuals, respectively, verifying the interference resistance of the antibody design used. On average, Architect hs-cTnI assay gave seven-fold higher cTnI concentrations than the new assay but the correlation between the assays was good (r=0.958). Of apparently healthy individuals (n=159), 18% had measurable cTnI values (>LoD) and 10% were cTnAAb-positive. The proportion of measurable cTnI values, however, was significantly higher in cTnAAb-positive individuals (13/16, median cTnI 8.5 ng/L) than in cTnAAb-negative individuals (15/143, median cTnI <LoD) (p<0.001). Conclusions: Although the developed sensitive cTnI assay without cTnAAb interference takes too long for diagnostic purposes, it could serve as an important analytical tool for exploring the impact of cTnAAbs for cTn testing and for unraveling the etiology behind cTn-related autoimmune responses.

  • 15.
    Shen, Qiujin
    et al.
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Björkesten, Johan
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Galli, Joakim
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Ekman, Daniel
    Olink Biosci, Uppsala, Sweden..
    Broberg, John
    Olink Prote, Uppsala, Sweden..
    Nordberg, Niklas
    Olink Prote, Uppsala, Sweden..
    Tillander, Annika
    Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden..
    Kamali-Moghaddam, Masood
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Tybring, Gunnel
    Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden..
    Landegren, Ulf
    Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Strong impact on plasma protein profiles by precentrifugation delay but not by repeated freeze-thaw cycles, as analyzed using multiplex proximity extension assays2018In: Clinical Chemistry and Laboratory Medicine, ISSN 1434-6621, E-ISSN 1437-4331, Vol. 56, no 4, p. 582-594Article in journal (Refereed)
    Abstract [en]

    Background: A number of factors regarding blood collection, handling and storage may affect sample quality. The purpose of this study was to assess the impact on plasma protein profiles by delayed centrifugation and plasma separation and multiple freeze-thaw cycles.

    Methods: Blood samples drawn from 16 healthy individuals were collected into ethylenediaminetetraacetic acid tubes and kept either at 4 degrees C or 22 degrees C for 1-36 h prior to centrifugation. Plasma samples prepared 1 h after venipuncture were also subjected to two to eight cycles of freezing at -80 degrees C and thawing at 22 degrees C. Multiplex proximity extension assay, an antibody-based protein assay, was used to investigate the influence on plasma proteins.

    Results: Up to 36 h delay before blood centrifugation resulted in significant increases of 16 and 40 out of 139 detectable proteins in samples kept at 4 degrees C or 22 degrees C, respectively. Some increases became noticeable after 8 h delay at 4 degrees C but already after 1 h at 22 degrees C. For samples stored at 4 degrees C, epidermal growth factor (EGF), NF-kappa-B essential modulator, SRC, interleukin 16 and CD6 increased the most, whereas the five most significantly increased proteins after storage at 22 degrees C were CD40 antigen ligand (CD40-L), EGF, platelet-derived growth factor subunit B, C-X-C motif chemokine ligand 5 and matrix metallopeptidase 1 (MMP1). Only matrix metallopeptidase 7 (MMP7) decreased significantly over time and only after storage at 22 degrees C. No protein levels were found to be significantly affected by up to eight freeze-thaw cycles.

    Conclusions: Plasma should be prepared from blood after a limited precentrifugation delay at a refrigerated temperature. By contrast, the influence by several freeze-thaw cycles on detectable protein levels in plasma was negligible.

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