bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of Relaxin-2 Connecting Peptide (Pro-RLX2) in Human Blood Samples
Authors: Rehfeldt Miriam , Sparwasser Andrea , Funk Eugenia , Köhrle Josef , Bergmann Andreas 
Published: July 2018

Abstract

Background
The peptide hormone relaxin-2 is implicated in diverse physiological and pathophysiological processes. Several assays are available for quantification of human relaxin-2, but because stability of the mature peptide in serum is limited, measurement of the more stable connecting peptide (pro-RLX2) might be beneficial.

Methods
Pro-RLX2 was measured in a sandwich immunoluminometric assay using 2 monoclonal antibodies. The concentration of pro-RLX2 was detected in healthy pregnant (n = 100) and healthy male and nonpregnant female (n = 81) subjects and compared with the concentration of mature relaxin-2 in a subset of samples.

Results
The pro-RLX2 immunoassay has an analytical and functional assay sensitivity (FAS) of 1.59 pmol/L and 1.7 pmol/L, respectively. The analyte is stable in EDTA plasma samples for 8 days at room temperature, dilutes in a linear fashion, and recovery was 103%. The assay system is not biased by common interfering substances. Measurement of 80% of plasma samples from healthy males and females is below the FAS {median 1.49 pmol/L [interquartile range (IQR) of 0.925–2.14 pmol/L]}, and no concentration difference between male and nonpregnant female plasma samples was observed. The median plasma concentration in healthy pregnant women is increased up to 562 pmol/L (IQR 341–789 pmol/L). During pregnancy, pro-RLX2 concentrations decrease with increasing gestation. The correlation coefficient with the R&D assay for mature relaxin-2 was 0.96 (P &lt; 0.0001).

Conclusion
Pro-RLX2 is stable in plasma of healthy individuals. Although samples of pregnant women are reliably measurable, most samples from healthy nonpregnant women and men are below the detection limit. Determination of pro-RLX2 concentrations might indicate rate of synthesis of relaxin-2 during pregnancy and therapeutic application of recombinant relaxin (Serelaxin).
Validation of a Circulating Tumor-Derived DNA Blood Test for Detection of Methylated BCAT1 and IKZF1 DNA
Authors: Murray David H , Baker Rohan T , Gaur Snigdha , Young Graeme P , Pedersen Susanne K 
Published: July 2018

Abstract

Background
Colvera™ is a test that detects circulating tumor-derived DNA in patients with colorectal cancer by assaying for the presence of methylated BCAT1 and IKZF1 in blood. This study describes the analytical and clinical performance characteristics of the test.

Methods
Validation was performed in accordance with ISO15189 and National Pathology Accreditation Advisory Council requirements. Spiked samples including 264 plasma and 120 buffer samples were randomized, divided into 8 batches of 48 samples, and processed over 8 days using 2 equipment lines (each line consisting of a QIAsymphony SP/AS, QIACube HT, and LC480); 2 reagent batches; and 2 operators to determine limit of detection, selectivity/specificity, precision, reproducibility, ruggedness, and susceptibility to commonly known interfering substances. Clinical performance was validated by assaying 222 archived plasma samples from subjects (n = 26 with cancer) enrolled in a previous prospective trial.

Results
The limit of detection for Colvera was 12.6 pg/mL (95% CI, 8.6–23.9 pg/mL), which equates to 2 diploid genome copies per milliliter plasma. No statistically significant difference was determined between testing days (n = 8), instrumentation, operators, or reagent batches in precision studies for the methylation-specific assays. The assay performance was unaffected by 9 commonly known interference substances, variations in bisulfite conversion, or quantitative PCR settings (cycling temperatures, incubation times, and oligonucleotide concentrations). For this clinical cohort, sensitivity and specificity estimates for Colvera were 73.1% (19 of 26; 95% CI, 52.2–88.4) and 89.3% (175 of 196; 95% CI, 84.1–93.2), respectively.

Conclusion
Colvera is a robust test and suitable for detection of circulating tumor-derived DNA by measuring levels of methylated BCAT1 and IKZF1 in human blood plasma.
Pharmacogenetics of Opioid Use and Implications for Pain Management
Authors: Nerenz Robert D , Tsongalis Gregory J 
Published: July 2018

Abstract

Background
Opioid analgesics are frequently prescribed to manage acute and chronic pain, but individual differences in opioid response make effective pain control in all patients an elusive goal. Furthermore, the risk of addiction following opioid consumption varies among individual patients. Although many psychosocial factors contribute to an individual's opioid response and risk for addiction, a strong genetic component has also been demonstrated.

Content
Opioids undergo substantial enzymatic modification that can generate metabolites with either increased or decreased opioid activity relative to the parent compound. To elicit their analgesic effect, parent compounds and active metabolites must be transported into the central nervous system where they bind to opioid receptors and inhibit neurotransmission. Inherited genetic variants that alter the function of proteins involved in these processes have been associated with differences in opioid response and risk for addiction. Detection of these variants can help guide opioid selection, inform dosing decisions, or encourage use of a nonopioid analgesic.

Summary
Whereas some genetic variants are clearly associated with differences in opioid response and have been included in consensus clinical practice guidelines, the impact of other variants on opioid response remains unclear. Studies performed to date have generated promising results, but inconsistent findings, reimbursement challenges, and the lack of robust decision support tools have hampered widespread adoption of pharmacogenetic testing to guide pain management treatment decisions. Future work involving the simultaneous evaluation of large numbers of variants and demonstration of a clear clinical benefit provided by pharmacogenetic testing will be required to overcome these obstacles.
Planning Risk-Based Statistical Quality Control Strategies: Graphical Tools to Support the New Clinical and Laboratory Standards Institute C24-Ed4 Guidance
Authors: Bayat Hassan , Westgard Sten A , Westgard James O 
Published: July 2018

Abstract

Background
Clinical and Laboratory Standards Institute (CLSI)'s new guideline for statistical quality control (SQC; C24-Ed4) (CLSI C24-Ed4, 2016; Parvin CA, 2017) recommends the implementation of risk-based SQC strategies. Important changes from earlier editions include alignment of principles and concepts with the general patient risk model in CLSI EP23A (CLSI EP23A, 2011) and a recommendation for optimizing the frequency of SQC (number of patients included in a run, or run size) on the basis of the expected number of unreliable final patient results. The guideline outlines a planning process for risk-based SQC strategies and describes 2 applications for examination procedures that provide 9-σ and 4-σ quality. A serious limitation is that there are no practical tools to help laboratories verify the results of these examples or perform their own applications.

Methods
Power curves that characterize the rejection characteristics of SQC procedures were used to predict the risk of erroneous patient results based on Parvin's MaxE(Nuf) parameter (Clin Chem 2008;54:2049–54). Run size was calculated from MaxE(Nuf) and related to the probability of error detection for the critical systematic error (Pedc).

Results
A plot of run size vs Pedc was prepared to provide a simple nomogram for estimating run size for common single-rule and multirule SQC procedures with Ns of 2 and 4.

Conclusions
The “traditional” SQC selection process that uses power function graphs to select control rules and the number of control measurements can be extended to determine SQC frequency by use of a run size nomogram. Such practical tools are needed for planning risk-based SQC strategies.
Proenkephalin (PENK) as a Novel Biomarker for Kidney Function
Authors: Beunders Remi , Struck Joachim , Wu Alan H B , Zarbock Alexander , Di Somma Salvatore , Mehta Ravindra L , Koyner Jay L , Nadim Mitra K , Maisel Alan S , Murray Patrick T , Neath Sean-Xavier , Jaffe Allan , Pickkers Peter 
Published: July 2018

Abstract

Background
The assessment of kidney function and detection of acute kidney injury (AKI) remain cumbersome. On the one hand, because of limited accuracy of established tests: The most widely used methods are creatinine based, which lack in sensitivity, as creatinine is not purely filtrated by the kidney and rises relatively late after onset of AKI. On the other hand, because of labor-intensiveness: Gold standard inulin clearance and comparable methods involve intravenous compound infusion, blood sampling at several time points, and have error-sensitive determination methods. In recent years, several biomarkers have been put forward (e.g., NGAL, KIM-1, TIMP-2*IGFBP-7), but clinical implementation is limited up to now.

Content
Proenkephalin (PENK) represents a new candidate to determine kidney function. This peptide is cleaved from the precursor peptide preproenkephalin A alongside enkephalins (endogenous opioids) and is filtrated in the glomerulus. PENK plasma concentration appears to accurately represent glomerular filtration rate in patients diagnosed with sepsis or cardiac diseases. Moreover, increased PENK concentration is found to be associated with longer-term outcome concerning AKI and cardiac diseases. Lastly, the predominant receptor of enkephalins, the δ-opioid receptor, is expressed with the highest density in the kidney, suggesting that enkephalins could also exert a direct effect on kidney function.

Summary
In this review, we present an overview of enkephalins and the assessment of kidney function using this possible new functional biomarker PENK and compare it with established and novel biomarkers.
Transforming Laboratory Utilization Review into Laboratory Stewardship: Guidelines by the PLUGS National Committee for Laboratory Stewardship
Authors: Dickerson Jane A , Fletcher Andrew H , Procop Gary , Keren David F , Singh Ila R , Garcia Joaquin J , Carpenter Robert B , Miles Joe , Jackson Brian , Astion Michael L 
Published: July 2018

Abstract
Appropriate utilization of clinical laboratory services is important for patient care and requires institutional stewardship. Clinical laboratory stewardship programs are dedicated to improving the ordering, retrieval, and interpretation of appropriate laboratory tests. In addition, these programs focus on developing, maintaining, and improving systems to provide proper financial coverage for medically necessary testing. Overall, clinical laboratory stewardship programs help clinicians improve the quality of patient care while reducing costs to patients, hospitals, and health systems. This document, which was created by a new multiinstitutional committee interested in promoting and formalizing laboratory stewardship, summarizes core elements of successful hospital-based clinical laboratory stewardship programs. The core elements will also be helpful for independent commercial clinical laboratories.
Interindividual Variability and Normal Ranges of Whole Blood and Plasma Thrombin Generation
Authors: Bloemen Saartje , Huskens Dana , Konings Joke , Kremers Romy M , Miszta Adam , de Laat Bas , Kelchtermans Hilde 
Published: July 2018

Abstract

Background
Assays measuring thrombin generation (TG) in plasma increasingly gained attention in the field of thrombosis and hemostasis. Adaptation of the method enabled the measurement of TG in whole blood (WB). Despite their potential, TG assays did not reach the stage of universal clinical application, partly because of the absence of normal ranges. Our study aimed to accurately determine normal ranges and interindividual variability of TG and correlate results with coagulation factor levels, sex, and oral contraceptive usage.

Methods
The study protocol was evaluated by the local medical ethical board. In total, 129 healthy volunteers gave full informed consent. Normal ranges of TG in platelet-poor plasma (PPP), platelet-rich plasma (PRP), and WB were determined according to CLSI guidelines.

Results
Our study is the first to measure normal ranges of TG in PPP, PRP, and WB in a large healthy cohort. Significant correlations were found between TG in plasma and WB. Interindividual variability of TG in WB was comparable to that of plasma. Oral contraceptive use increased TG in PPP, PRP, and WB. The inhibitory effect of thrombomodulin on TG was significantly lower in females than in males. This effect was more pronounced upon oral contraceptive use. Primary clotting factor determinants for TG parameters depended on the tissue factor concentration, but were similar in WB and plasma.

Conclusions
Establishing normal ranges for TG brings us 1 step closer to clinical use. Good correlations between plasma and WB (including clotting factor determinants for TG) suggest that WB TG can be reliably used in clinic.
Sandwich Immunoassay for Bioactive Plasma Adrenomedullin
Authors: Weber Julia , Sachse Janine , Bergmann Sarah , Sparwaßer Andrea , Struck Joachim , Bergmann Andreas 
Published: July 2018

Abstract

Background
Adrenomedullin (ADM) is a circulating peptide known to regulate vasodilation and vascular integrity. Increased plasma ADM concentrations have been described for several life-threatening conditions, including cardiovascular diseases and septic shock. Reliable methods for the simple quantification of bioactive ADM (bio-ADM) are lacking.

Methods
Monoclonal antibodies against the amidated C-terminus and middle portion of bio-ADM were generated and used for the development of a 1-step immunometric assay for the specific quantification of bio-ADM in plasma. The assay was developed in a microtiter plate/chemiluminescence label format with a significantly reduced incubation time. Precision, linearity, specimen stability, and distribution of results in healthy subjects were evaluated.

Results
The use of monoclonal antibodies against predetermined epitopes of bio-ADM enabled the development of an assay for the determination of bio-ADM directly in EDTA plasma. Plasma samples were stable for up to 24 h at ambient temperature and over multiple freeze–thaw cycles without loss of immunoreactivity. The assay had a limit of detection of 3 pg/mL and a limit of quantification of 11 pg/mL. The assay exhibited acceptable linearity characteristics and was not influenced by complement factor H, a putative ADM-binding protein. In healthy subjects, bio-ADM concentrations were all above the limit of detection, and approximately half of them were above the limit of quantification.

Conclusions
By using monoclonal antibodies with defined epitope specificities, we have developed a simple, rapid, accurate, and sensitive sandwich immunoassay for bio-ADM. The assay is a potentially novel tool to support patient management, particularly in acute care in the field of sepsis and other indications, which are currently being investigated, such as acute heart failure.
Expanding the Utility of High-Sensitivity Dried Blood Spot Immunoassay Testing with Single Molecule Counting
Authors: Mukherjee Ali , Dang Tam , Morrell Heather , Yerramilli Rama , Bishop Jeffrey J 
Published: July 2018

Abstract

Background
Dried blood spot (DBS) testing has been used for years in newborn screening and for other applications when obtaining blood by venipuncture is impractical or expensive. However, several technical challenges have restricted the use of DBS testing to qualitative assays or to analytes that are present in relatively high concentrations. The application of high-sensitivity detection using single molecule counting (SMC™) technology can potentially overcome the limitations of DBS as specimen source.

Methods
A method was developed for reproducibly collecting, storing, and subsequently reconstituting DBS samples to be used with assays based on the SMC technology. Before extraction, DBS samples were scanned, and the blood spot area was calculated to normalize for sample volume and spot variability. DBS sample extraction was done using an efficient high-salt extraction buffer. DBS samples were tested using SMC-based cardiac troponin I (cTnI), prostate-specific antigen (PSA), and C-reactive protein (CRP) assays.

Results
The SMC-DBS assays showed reproducible sensitivity, precision, and the stability required for quantifying low-abundance biomarkers. These assays were not significantly impacted by normal variations in hematocrit or sample collection technique. Correlation coefficients obtained from method comparisons between SMC-DBS and laboratory-developed tests or Food and Drug Administration-cleared tests using traditional sample types were 1.08, 1.04, and 0.99 for cTnI, PSA, and high-sensitivity CRP, respectively.

Conclusions
Combining DBS finger-stick blood collection with next-generation immunoassay technology will aid the expansion of DBS testing to protein biomarkers that are in low abundance or to low-volume samples, and will enable the development and adoption of DBS testing to far-reaching applications.
Variability in Microplate Surface Properties and Its Impact on ELISA
Authors: Lilyanna Shera , Ng Enoch Ming Wei , Moriguchi Shiho , Chan Siew Pang , Kokawa Ryohei , Huynh So Hung , Chong P C Jenny , Ng Yan Xia , Richards A Mark , Ng Tuck Wah , Liew Oi Wah 
Published: July 2018

Abstract

Background
Microplate-based immunoassays are widely used in clinical and research settings to measure a broad range of biomarkers present in complex matrices. Assay variability within and between microplates can give rise to false-negative and false-positive results leading to incorrect conclusions. To date, the contribution of microplates to this variability remains poorly characterized and described. This study provides new insights into variability in immunoassays attributable to surface characteristics of commercial microplates.

Methods
Well-to-well assay variation in γ-treated and nontreated 96-well opaque microplates suitable for chemiluminescence assays was determined by use of a validated sandwich ELISA. Microplate surface characteristics were assessed by sessile drop contact angle measurements, scanning electron microscopy, energy dispersive x-ray spectroscopy, and atomic force microscopy.

Results
All microplate types tested exhibited vendor-specific assay response profiles; and “rogue” plates with very high intraassay variation and deviant mean assay responses were found. Within-plate, location-dependent bias in assay responses and variability in well contact angle were also observed. We demonstrate substantial differences in well-surface properties with putative effects on protein-coating reproducibility and hence consistency in immunoassay responses. A surface “cleaning” effect on manufacturing residues was attributed to γ-irradiation, and treated microplates manifest increased polar functionalities, surface roughness, and assay responses.

Conclusions
Our data suggest that tighter control of variability in surface roughness, wettability, chemistry, and level of residual contaminants during microplate preparation is warranted to improve consistency of ELISA assay read out.
Opioids: Clinical Practice, Monitoring, and Medicolegal Considerations
Authors: Eldrige Jason S , Rho Richard H , Martin Joanne L , Murphy Joshua B , Hooten W Michael 
Published: July 2018

Abstract

Background
In the past decade, opioid use in the general population of the US has increased dramatically. Concomitantly, opioid-related morbidity and mortality have also risen steeply. The causes of opioid over-prescribing are multifactorial, with pressure from medical agencies, patients, aggressive patient-directed marketing, and use of patient surveys as an evaluation tool to unduly influence medical providers' decision-making. Providers also have significant concerns regarding scrutiny from their medical board and exposure to medicolegal liability.

Content
To provide the basis for best practice recommendations, several aspects of modern opioid prescribing practice require review. The practicing clinician should be aware of: (a) the pervasiveness of current opioid prescribing within the US; (b) the availability and applicability of clinical tools used to assess patient risk; (c) the new guidelines designed to facilitate appropriate and safe medical use of opioids; (d) the incorporation of clinical tools and best documentation practices to reduce medicolegal exposure.

Summary
On completion of this review, the reader should be able to recognize the magnitude of the problem of opioid over-prescribing in the US and identify several patient risk factors for opioid misuse, abuse, and/or diversion. Specifically, better familiarity with the recently published CDC guidelines for opioid prescribing will help ensure the adoption of best-use practices that maximize therapeutic efficacy while attenuating the possibility of harm to patients. A thorough review of the legal principles and risk-mitigation strategies relevant to opioid prescribing will also lessen the clinician's exposure to medicolegal liability.
Mass Spectrometric Identification of Cardiac Troponin T in Urine of Patients Suffering from Acute Myocardial Infarction
Authors: Streng Alexander S , van der Linden Noreen , Kocken Jordy M M , Bekers Otto , Bouwman Freek G , Mariman Edwin C M , Meex Steven J R , Wodzig Will K W H , de Boer Douwe 
Published: July 2018

Abstract

Background
Because of its high cardiospecificity, cardiac troponin T (cTnT) is one of the first-choice biomarkers to diagnose acute myocardial infarction (AMI). cTnT is extensively fragmented in serum of patients suffering from AMI. However, it is currently unknown whether all cTnT is completely degraded in the body or whether some cTnT fragments can leave the body via urine. The aim of the present study is to develop a method for the detection of cTnT in urine and to examine whether cTnT is detectable in patient urine.

Methods
Proteins in urine samples of 20 patients were precipitated using a cTnT-specific immunoprecipitation technique and a nonspecific acetonitrile protein precipitation. After in-solution digestion of the precipitated proteins, the resulting peptides were separated and analyzed using HPLC and mass spectrometry with a targeted selected ion monitoring assay with data-dependent tandem mass spectrometry (t-SIM/dd-MS2).

Results
The t-SIM/dd-MS2 assay was validated using a synthetic peptide standard containing 10 specific cTnT peptides of interest and with purified human intact cTnT spiked in urine from healthy individuals. Using this assay, 6 different cTnT-specific peptides were identified in urine samples from 3 different patients, all suffering from AMI.

Conclusions
We show here for the first time that cTnT can be present in the urine of AMI patients using a targeted LC-MS/MS assay. Whether the presence of cTnT in urine reflects a physiological or pathophysiological process still needs to be elucidated.