Serum Biomarkers (serum + biomarker)

Distribution by Scientific Domains


Selected Abstracts


Serum biomarker profiling by solid-phase extraction with particle-embedded micro tips and matrix-assisted laser desorption/ionization mass spectrometry,

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2008
Arti Navare
One of the main challenges in high-throughput serum profiling by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is the development of proteome fractionation approaches that allow the acquisition of reproducible profiles with a maximum number of spectral features and minimum interferences from biological matrices. This study evaluates a new class of solid-phase extraction (SPE) pipette tips embedded with different chromatographic media for fractionation of model protein digests and serum samples. The materials embedded include strong anion exchange (SAX), weak cation exchange (WCX), C18, C8, C4, immobilized metal affinity chromatography (IMAC) and zirconium dioxide particles. Simple and rapid serum proteome profiling protocols based on these SPE micro tips are described and tested using a variety of MALDI matrices. We show that different types of particle-embedded SPE micro tips provide complementary information in terms of the spectral features detected for , -casein digests and control human serum samples. The effect of different sample pretreatments, such as serum dilution and ultrafiltration using molecular weight cut-off membranes, and the reproducibility observed for replicate experiments, are also evaluated. The results demonstrate the usefulness of these simple SPE tips combined with offline MALDI-TOF MS for obtaining information-rich serum profiles, resulting in a robust, versatile and reproducible open-source platform for serum biomarker discovery. Copyright © 2008 John Wiley & Sons, Ltd. [source]


Serum biomarker for progranulin-associated frontotemporal lobar degeneration,

ANNALS OF NEUROLOGY, Issue 5 2009
Kristel Sleegers MD
Objective Mutations that lead to a loss of progranulin (PGRN) explain a considerable portion of the occurrence of frontotemporal lobar degeneration. We tested a biomarker allowing rapid detection of a loss of PGRN. Methods We used an enzyme-linked immunosorbent assay to measure in serum the PGRN protein levels of six affected and eight unaffected carriers from within an extended Belgian founder family segregating the null mutation IVS1+5G>C. Further, we measured serum PGRN levels in 2 patients with another null mutation (a Met1 and a frameshift mutation), in 4 patients carrying a predicted pathogenic missense mutation and in 5 patients carrying a benign missense polymorphism, in 9 unaffected noncarrier relatives, and in 22 community controls. Results Serum PGRN levels were reduced in both affected and unaffected null mutation carriers compared with noncarrier relatives (pexact < 0.0001), and allowed perfect discrimination between carriers and noncarriers (sensitivity: 1.0; 1 , specificity: 0.0). Serum PGRN levels in Cys139Arg and Arg564Cys mutation carriers were significantly lower than in controls, but greater than in null mutation carriers, fitting the hypothesis of partial loss of function caused by these missense mutations. As expected, levels for carriers of benign missense polymorphisms were not significantly different from controls. Interpretation Our results indicate that the serum PGRN level is a reliable biomarker for diagnosing and early detection of frontotemporal lobar degeneration caused by PGRN null mutations, and provided the first in vivo evidence that at least some missense mutations in PGRN may lead to a (partial) loss of PGRN. Ann Neurol 2009 [source]


Telangiectatic adenoma: An entity associated with increased body mass index and inflammation,

HEPATOLOGY, Issue 1 2007
Valérie Paradis
What were previously called telangiectatic focal nodular hyperplasias are in fact true adenomas with telangiectatic features (TAs) without overt characterized genetic abnormalities. The aim of our study was to review a surgical series of TAs in order to describe clinical, biological, and radiological findings of these lesions and to evaluate their outcomes. From January 1996 to November 2005, 284 patients with benign hepatocellular nodules underwent surgical resection at Beaujon Hospital. Among them, 32 TAs from 27 patients were diagnosed. Ninety-two percent of the patients were women. Mean age was 38 years (range 17,63). Mean body mass index was 28 (range 18,49), with 16 patients being overweight. Symptoms revealed lesions in 10 patients. In 13 patients, TA was associated with another benign liver lesion. Mean size of the TAs was 5 cm (range 1,17 cm). Histological analysis showed cellular atypias in 6 cases (19%), steatosis in 17 cases (53%), vascular changes in 19 cases (59%), and significant inflammatory infiltrate in 29 cases (91%). In 1 case, the TA had foci of well-differentiated hepatocellular carcinoma. In 18 of the 26 cases (69%), adjacent liver showed significant steatosis. Serum biomarkers of inflammation were increased in 90% of patients (19 of 22). After surgical resection, inflammatory marker levels returned to normal values in all patients tested. Conclusion: This study has shown that TAs occur in a characteristic background of overweight patients and are often associated with a biological inflammatory syndrome. Moreover, a TA may progress to malignancy. (HEPATOLOGY 2007;46:140,146.) [source]


Serum biomarkers of hepatitis B virus infected liver inflammation: A proteomic study

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2003
Qing-Yu He
Abstract Hepatitis B virus (HBV), a serious infectious and widespread human pathogen, represents a major health problem worldwide. Chronic HBV infection has a very high risk of evolving into hepatocellular carcinoma. Although considerable progress was made during the recent past, the pathogenesis of HBV infection is still elusive and a definite diagnosis of HBV infected liver information still relies on biopsy histological test. In this report, we used proteomics technology to globally examine HBV infected serum samples aiming at searching for disease-associated proteins that can be used as serological biomarkers for diagnosis and/or target proteins for pathogenetic study. By comparing with normal and HBV negative serum samples, we found that at least seven proteins were significantly changed in HBV infected sera. These greatly altered proteins were identified to be haptoglobin , and ,2 chain, apolipoprotein A-I and A-IV, ,1-antitrypsin, transthyretin and DNA topoisomerase II,. The alteration of these proteins is displayed not only in quantity but also in patterns (or specificity), which can be correlated with necroinflammatory scores. In particular, apolipoprotein A-I presents heterogeneous change in expression level with different isoforms and ,1-antitrypsin produces evidently different fragments implying diverse cleavage pathways. These unique phenomena appear specific to HBV infection. A combination simultaneously considering the quantities and isoforms of these proteins could be a useful serum biomarker (or index) for HBV diagnosis and therapy. [source]


Use of serum biomarkers in a diagnostic test for irritable bowel syndrome

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009
A. J. LEMBO
Summary Background Currently, no single serum biomarker can reliably differentiate irritable bowel syndrome (IBS) from other functional gastrointestinal disorders or organic diseases of the gastrointestinal tract. Aim To develop and validate a diagnostic test using serum biomarkers to detect IBS. Methods Ten serum biomarkers were selected from a potential panel of 140 for their ability to differentiate IBS from non-IBS disease in blood samples from patients with IBS, other gastrointestinal disorders and healthy volunteers. A predictive modelling tool was developed to assess patterns and relationships among the 10 serum biomarkers that best differentiated IBS patients from healthy controls and patients with non-IBS gastrointestinal disease. This model was tested in a different cohort of patients and healthy controls (n = 516) to determine the predictive accuracy of differentiating IBS from non-IBS. Results The sensitivity and specificity of the 10-biomarker algorithm for differentiating IBS from non-IBS was 50% and 88% respectively. The positive predictive value was 81%, and the negative predictive value was 64% at 50% IBS prevalence in the validation cohort. Overall accuracy was 70%. Conclusions Assessing serum biomarker patterns can differentiate IBS from non-IBS with reasonable sensitivity and specificity. Assessing serum biomarkers in an overall diagnostic strategy may allow earlier diagnosis and treatment for patients with IBS. [source]


Serum biomarkers of hepatitis B virus infected liver inflammation: A proteomic study

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2003
Qing-Yu He
Abstract Hepatitis B virus (HBV), a serious infectious and widespread human pathogen, represents a major health problem worldwide. Chronic HBV infection has a very high risk of evolving into hepatocellular carcinoma. Although considerable progress was made during the recent past, the pathogenesis of HBV infection is still elusive and a definite diagnosis of HBV infected liver information still relies on biopsy histological test. In this report, we used proteomics technology to globally examine HBV infected serum samples aiming at searching for disease-associated proteins that can be used as serological biomarkers for diagnosis and/or target proteins for pathogenetic study. By comparing with normal and HBV negative serum samples, we found that at least seven proteins were significantly changed in HBV infected sera. These greatly altered proteins were identified to be haptoglobin , and ,2 chain, apolipoprotein A-I and A-IV, ,1-antitrypsin, transthyretin and DNA topoisomerase II,. The alteration of these proteins is displayed not only in quantity but also in patterns (or specificity), which can be correlated with necroinflammatory scores. In particular, apolipoprotein A-I presents heterogeneous change in expression level with different isoforms and ,1-antitrypsin produces evidently different fragments implying diverse cleavage pathways. These unique phenomena appear specific to HBV infection. A combination simultaneously considering the quantities and isoforms of these proteins could be a useful serum biomarker (or index) for HBV diagnosis and therapy. [source]


Discovery of diagnostic serum biomarkers of gastric cancer using proteomics

PROTEOMICS - CLINICAL APPLICATIONS, Issue 2 2008
Katie Wing-kei Lam
Abstract Gastric cancer has significant morbidity and mortality worldwide and locally. Good prognosis relies on an early diagnosis. However, this remains a challenge due to the lack of specific and sensitive serum biomarkers for early detection. Hence, there is a constant search for these biomarkers for screening purposes. Proteomic profiling enables a new approach to the discovery of biomarkers in disease. This review presents recent attempts in search of gastric cancer serum biomarker using proteomics. Different methodologies and different types of samples were employed by different groups of researchers. Major difficulties were encountered in the discovery processes, including interference from abundant proteins and continuous changing serum proteomes from different individuals. [source]


Can serum biomarker assays measure the progression of cartilage degeneration in osteoarthritis?

ARTHRITIS & RHEUMATISM, Issue 10 2002
A. Robin Poole
First page of article [source]


Gastrin-releasing peptide: Different forms, different functions

BIOFACTORS, Issue 1 2009
Joseph Ischia
Abstract All forms of the neuropeptide gastrin-releasing peptide (GRP) are derived from the precursor proGRP1-125. Amidated GRP18-27, which together with amidated GRP1-27 was long thought to be the only biologically relevant product of the GRP gene, is involved in a multitude of physiological functions and acts as a mitogen, morphogen, and proangiogenic factor in certain cancers. Recently, GRP has been implicated in several psychiatric conditions, in the maintenance of circadian rhythm, in spinal transmission of the itch sensation, and in inflammation and wound repair. The actions of GRP are mediated by the GRP receptor. Over the last decade, nonamidated peptides derived from proGRP, such as the glycine-extended form GRP18-28 and recombinant and synthetic fragments from proGRP31-125, have been shown to be biologically active in a range of tissues and in cancer cell lines. While GRP18-28 acts via the GRP receptor, the identity of the receptor for proGRP31-125 and its fragments has not yet been established. Nonamidated fragments are also present in normal tissues and in various cancers. In fact, proGRP31-98 is the most sensitive serum biomarker in patients with small cell lung cancer and is a significant predictor of poor survival in patients with advanced prostate cancer. © 2009 International Union of Biochemistry and Molecular Biology, Inc. [source]


No increases in biomarkers of genetic damage or pathological changes in heart and brain tissues in male rats administered methylphenidate hydrochloride (Ritalin) for 28 days,,

ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 1 2010
Kristine L. Witt
Abstract Following a 2005 report of chromosomal damage in children with attention deficit/hyperactivity disorder (ADHD) who were treated with the commonly prescribed medication methylphenidate (MPH), numerous studies have been conducted to clarify the risk for MPH-induced genetic damage. Although most of these studies reported no changes in genetic damage endpoints associated with exposure to MPH, one recent study (Andreazza et al. [2007]: Prog Neuropsychopharmacol Biol Psychiatry 31:1282,1288) reported an increase in DNA damage detected by the Comet assay in blood and brain cells of Wistar rats treated by intraperitoneal injection with 1, 2, or 10 mg/kg MPH; no increases in micronucleated lymphocyte frequencies were observed in these rats. To clarify these findings, we treated adult male Wistar Han rats with 0, 2, 10, or 25 mg/kg MPH by gavage once daily for 28 consecutive days and measured micronucleated reticulocyte (MN-RET) frequencies in blood, and DNA damage in blood, brain, and liver cells 4 hr after final dosing. Flow cytometric evaluation of blood revealed no significant increases in MN-RET. Comet assay evaluations of blood leukocytes and cells of the liver, as well as of the striatum, hippocampus, and frontal cortex of the brain showed no increases in DNA damage in MPH-treated rats in any of the three treatment groups. Thus, the previously reported observations of DNA damage in blood and brain tissue of rats exposed to MPH for 28 days were not confirmed in this study. Additionally, no histopathological changes in brain or heart, or elevated serum biomarkers of cardiac injury were observed in these MPH-exposed rats. Environ. Mol. Mutagen. 2010. Published 2009 Wiley-Liss, Inc. [source]


New proteomic approaches for biomarker discovery in inflammatory bowel disease

INFLAMMATORY BOWEL DISEASES, Issue 7 2010
Giulia Roda MD
Abstract There is an increasing interest in the discovery of new inflammatory bowel disease (IBD) biomarkers able to predict the future patterns of disease and to help in diagnosis, treatment, and prognosis. A biomarker is a substance that can be measured biologically and is associated with an increased risk of the disease. Biomarkers can be a genetic testing factor or proteins in biological samples such as serum, plasma, and cellular subpopulations. All of them should be studied to find out their utility in the management of IBD. Ulcerative colitis and Crohn's disease are relapsing and remitting chronic IBDs characterized by a global immune defect. The gold standard of their diagnosis is histological evaluation performed during endoscopic procedures. Several studies have focused on the identification and combination of less invasive diagnostic serum biomarkers. Nowadays, diagnostic serum tests are not able either to determine whether and when the relapse will occur once the disease is in remission state or to select a patient phenotype more responsive to a specific therapy and more susceptible to different types of complication. In this review we analyze and report the current understanding in IBD biomarkers and discuss potential future biomarkers and new developments of proteomics, such as subproteomics, as an innovative approach for the classification of patients according to their pattern of protein expression. (Inflamm Bowel Dis 2010) [source]


Risk prediction for Down's syndrome in young pregnant women using maternal serum biomarkers: determination of cut-off risk from receiver operating characteristic curve analysis

JOURNAL OF EVALUATION IN CLINICAL PRACTICE, Issue 2 2007
Hsiao-Lin Hwa MD PhD
Abstract Objective, The aim of this study was to establish a predictive model for Down's syndrome using maternal age as well as maternal serum levels of alpha-fetoprotein (AFP) and human chorionic gonadotropin (hCG), and to identify an optimal cut-off risk in women under the age of 35 years to improve sensitivity. Methods, Logistic regression models were utilized to predict fetal Down's syndrome as a function of maternal age and logarithm of levels of AFP as well as hCG using training data of 20 pregnancies with fetal Down's syndrome and 9730 unaffected pregnancies. Validation was performed using data of another nine affected pregnancies and 3496 unaffected pregnancies. Receiver operating characteristic (ROC) curves were plotted. Results, Based on the newly established logistic regression equations, the optimal cut-off risk from the ROC curve analysis was at 1:499, with a 17.8% false-positive rate and a 90.0% sensitivity. A suboptimal cut-off risk was estimated at 1:332, with a 12.0% false-positive rate and an 80% sensitivity. Conclusion, A predictive model for Down's syndrome was developed using logistic regression. By ROC curve analysis and clinical consideration, the cut-off risk for young pregnant women could be determined. [source]


Low-intensity pulsed ultrasound (LIPUS) increases the articular cartilage type II collagen in a rat osteoarthritis model

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2010
Kiyohito Naito
Abstract In this study, the effect of low-intensity pulsed ultrasound (LIPUS) on cartilage was evaluated in a rat osteoarthritis (OA) model using serum biomarkers such as CTX-II (type II collagen degradation) and CPII (type II collagen synthesis) as well as histological criteria (Mankin score and immunohistochemical type II collagen staining). OA was surgically induced in the knee joint of rats by anterior cruciate/medial collateral ligament transection and medial meniscus resection (ACLT,+,MMx). Animals were divided into three groups: sham-operated group (Sham), ACLT,+,MMx group without LIPUS (,LIPUS), and ACLT,+,MMx group with LIPUS (+LIPUS; 30 mW/cm2, 20 min/day for 28 days). CTX-II levels were elevated in both ,LIPUS and +LIPUS groups compared to that in the Sham group after the operation, but there was no significant difference between +LIPUS and ,LIPUS groups, suggesting that LIPUS does not affect the degradation of type II collagen in this model. In contrast, CPII was significantly increased in +LIPUS group compared to ,LIPUS and Sham. Moreover, histological damage on the cartilage (Mankin score) was ameliorated by LIPUS, and type II collagen was immunohistochemically increased by LIPUS in the cartilage of an OA model. Of interest, mRNA expression of type II collagen was enhanced by LIPUS in chondrocytes. Together these observations suggest that LIPUS is likely to increase the type II collagen synthesis in articular cartilage, possibly via the activation of chondrocytes and induction of type II collagen mRNA expression, thereby exhibiting chondroprotective action in a rat OA model. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:361,369, 2010 [source]


Use of serum biomarkers in a diagnostic test for irritable bowel syndrome

ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009
A. J. LEMBO
Summary Background Currently, no single serum biomarker can reliably differentiate irritable bowel syndrome (IBS) from other functional gastrointestinal disorders or organic diseases of the gastrointestinal tract. Aim To develop and validate a diagnostic test using serum biomarkers to detect IBS. Methods Ten serum biomarkers were selected from a potential panel of 140 for their ability to differentiate IBS from non-IBS disease in blood samples from patients with IBS, other gastrointestinal disorders and healthy volunteers. A predictive modelling tool was developed to assess patterns and relationships among the 10 serum biomarkers that best differentiated IBS patients from healthy controls and patients with non-IBS gastrointestinal disease. This model was tested in a different cohort of patients and healthy controls (n = 516) to determine the predictive accuracy of differentiating IBS from non-IBS. Results The sensitivity and specificity of the 10-biomarker algorithm for differentiating IBS from non-IBS was 50% and 88% respectively. The positive predictive value was 81%, and the negative predictive value was 64% at 50% IBS prevalence in the validation cohort. Overall accuracy was 70%. Conclusions Assessing serum biomarker patterns can differentiate IBS from non-IBS with reasonable sensitivity and specificity. Assessing serum biomarkers in an overall diagnostic strategy may allow earlier diagnosis and treatment for patients with IBS. [source]


Identification of second trimester screen positive pregnancies at increased risk for congenital heart defects

PRENATAL DIAGNOSIS, Issue 6 2009
Laura L. Jelliffe-Pawlowski
Abstract Objective To examine whether second trimester biomarkers could be used to identify screen positive pregnancies at increased risk for congenital heart defects (CHDs) and measure the effect of using different biomarker cut points on the detection of CHDs and on the performance of predictive models. Methods Included were 19,402 pregnancies without chromosomal defects, which were screen positive for Down syndrome or other birth defects based on maternal serum measurements of alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), and unconjugated estriol (uE3). Logistic regression models were built that compared biomarkers for CHD cases compared to controls. Results CHD cases were more likely to be screen positive for trisomy-18, to have a nuchal fold (NF) , 5 mm, and/or to have an hCG multiple of the median (MoM) , 95th percentile in models that considered screen positive grouping. In models that did not consider screen positive grouping, cases were more likely to have a NF , 5 mm, an AFP MoM ,10th percentile, an hCG MoM ,25th percentile, and/or an hCG MoM , 75th percentile. Conclusion Along with NF, second trimester maternal serum biomarkers may be useful indicators for fetal and newborn evaluation for CHDs in screen positive pregnancies without identified chromosomal defects. Copyright © 2009 John Wiley & Sons, Ltd. [source]


Identification of breast cancer biomarkers in transgenic mouse models: A proteomics approach

PROTEOMICS - CLINICAL APPLICATIONS, Issue 6-7 2010
Wendy Rodenburg
Abstract Purpose: Transgenic mouse models for cancer circumvent many challenges that hamper human studies aimed at biomarker discovery. Lower biological variances among mice combined with controllable factors such as food uptake and health status may enable the detection of more subtle protein expression differences. This is envisioned to result in the identification of biomarkers better discriminating cancer cases from controls. Experimental design: The current study used two innovative mouse models for breast-cancer to identify new serum biomarkers. Multi-analyte profiling technique was used to analyze 70 proteins in individual serum samples of non-tumor and mammary tumor-bearing Tg.NK (MMTV/c-neu) mice. Results: A small set of proteins fully differentiated tumor samples from controls. These comprised osteopontin, interleukin-18, cystatin C and CD40 antigen. Comparison of protein expression in another breast-cancer mouse model, the humanized p53.R270H mice, showed common discriminatory expression of osteopontin. However, other biomarkers showed distinct expression in the two different breast-cancer models, indicating that different mammary tumor sub-types with respect to molecular and estrogen receptor status reveal divergent serum biomarker sets. Conclusions and clinical relevance: The current study supports the concept that serum proteins can discriminate mammary tumor cases from controls, and yielded interesting biomarkers that need further testing and validation in human studies. [source]


Discovery of diagnostic serum biomarkers of gastric cancer using proteomics

PROTEOMICS - CLINICAL APPLICATIONS, Issue 2 2008
Katie Wing-kei Lam
Abstract Gastric cancer has significant morbidity and mortality worldwide and locally. Good prognosis relies on an early diagnosis. However, this remains a challenge due to the lack of specific and sensitive serum biomarkers for early detection. Hence, there is a constant search for these biomarkers for screening purposes. Proteomic profiling enables a new approach to the discovery of biomarkers in disease. This review presents recent attempts in search of gastric cancer serum biomarker using proteomics. Different methodologies and different types of samples were employed by different groups of researchers. Major difficulties were encountered in the discovery processes, including interference from abundant proteins and continuous changing serum proteomes from different individuals. [source]


Promising Diagnostic Biomarkers for Primary Biliary Cirrhosis Identified With Magnetic Beads and MALDI-TOF-MS

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 3 2009
Yong-Zhe Li
Abstract (PBC) is not a rare disease worldwide. Most patients are diagnosed at the advanced stage, primarily because there are not yet any valid biomarkers available for early diagnosis. Useful biomarkers are absolutely necessary for early detection of PBC. Fortunately, the use of MALDI-TOF-MS and pattern recognition software has been successful in finding specific markers for the early detection of the disease. To screen for potential protein biomarkers in the serum for diagnosing PBC, MALDI-TOF-MS combined with magnetic beads and pattern recognition software was used to investigate 119 serum samples from 44 patients with PBC, 32 controls with other hepatic disease, and 43 healthy controls. A total of 69 discriminant m/z peaks were identified as being associated with PBC. Of them, the m/z peaks at 3445, 4260, 8133, and 16,290 were used to construct a model for the diagnosis of PBC. This diagnostic model can distinguish PBC from non-PBC controls with a sensitivity of 93.3% and a specificity of 95.1%. In our blind test, it demonstrated good sensitivity and specificity: 92.9% and 82.4%, respectively. These results indicate that useful serum biomarkers for PBC can be discovered by MALDI-TOF-MS combined with the use of magnetic beads and pattern recognition software. The pattern of multiple markers provides a powerful and reliable diagnostic method for PBC with high sensitivity and specificity. Anat Rec, 292:455,460, 2009. © 2009 Wiley-Liss, Inc. [source]


Comparing the Areas Under Two Correlated ROC Curves: Parametric and Non-Parametric Approaches

BIOMETRICAL JOURNAL, Issue 5 2006
Katy Molodianovitch
Abstract In order to compare the discriminatory effectiveness of two diagnostic markers the equality of the areas under the respective Receiver Operating Characteristic Curves is commonly tested. A non-parametric test based on the Mann-Whitney statistic is generally used. Weiand et al. (1989) present a parametric test based on normal distributional assumptions. We extend this test using the Box-Cox power family of transformations to non-normal situations. These three test procedures are compared in terms of significance level and power by means of a large simulation study. Overall we find that transforming to normality is to be preferred. An example of two pancreatic cancer serum biomarkers is used to illustrate the methodology. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]