bluuebunny/crossref_metadata_2025_split huggingface dataset:
Promoting Safe and Effective Genetic Tests in the United States: Work of the Task Force on Genetic Testing
Authors: Holtzman Neil A 
Published: January 2020

Abstract
The Task Force on Genetic Testing was created to review genetic testing in the United States and, when necessary, to make recommendations to ensure the development of safe and effective genetic tests. A survey to explore the state of genetic testing was undertaken for the Task Force and completed in early 1995. The survey, as well as literature reports and other information collected for the Task Force, showed problems affecting safety and effectiveness, as defined by the Task Force: validity and utility of predictive tests, laboratory quality, and appropriate use by healthcare providers and consumers. On the basis of these findings, the Task Force made several recommendations to ensure safe and effective genetic testing. The Secretary of Health and Human Services followed up one recommendation by creating the Secretary’s Advisory Committee on Genetic Testing. One of its functions will be to implement other recommendations of the Task Force.
Genetic Testing and the Clinical Laboratory Improvement Amendments of 1988: Present and Future
Authors: Schwartz Morton K 
Published: January 2020

AbstractCLIA ‘88 superseded CLIA ‘67. CLIA ‘88 set standards designed to improve quality and expanded federal oversight to virtually all clinical laboratories in the United States. Presumably because genetics testing was then in its infancy, CLIA ‘88 did not devote a special section to genetics testing. Biochemical and immunochemical tests used to evaluate inborn errors of metabolism and other genetic entities were categorized as analytes in the Clinical Chemistry section, and DNA probes used primarily in infectious disease were included in Microbiology. The legal, social, economic, and ethical implications of genetic testing and the rapid commercialization of these tests led to recommendations that genetic testing be defined as a laboratory specialty with a subsection in CLIA. The advisory committee created under CLIA was assigned to review these recommendations. The committee agreed that genetics testing was sufficiently different from other areas already included in CLIA to warrant a separate section. Two definitions were adopted. The more clear-cut one is for molecular genetic and cytogenic tests. This includes the analysis of human DNA/RNA in evaluating genetic diseases. The second definition is not as clear-cut and is for the analysis of proteins and metabolites used predominantly to detect inborn errors of metabolism. Many of these analytes already are categorized according to their uses for other purposes. The recommendations for genetic testing include detailed and specific proposals concerning personnel, confidentiality and informed consent, quality control, contamination, proficiency testing, validation of tests, special reporting, retention of records, and reuse of tested specimens.
Development of an Ultrasensitive Immunoassay for Human Glandular Kallikrein with No Cross-Reactivity from Prostate-specific Antigen
Authors: Black Margot H , Magklara Angeliki , Obiezu Christina V , Melegos Dimitrios N , Diamandis Eleftherios P 
Published: January 2020

Abstract
Background: Studies demonstrating that human glandular kallikrein (hK2) is increased in prostate cancer patients have prompted speculation that this marker may of use in addition to prostate-specific antigen (PSA).
Methods: An ultrasensitive hK2 sandwich immunoassay was developed, and its detection limit, cross-reactivity, analytical recovery, precision, and linearity of dilution were evaluated. hK2 was measured in seminal plasma and sera from healthy males, females, and prostatectomized patients.
Results: Our assay has an excellent detection limit (6 ng/L) and precision (&gt;90%). Recovery studies indicated that hK2 binds to serum protease inhibitors. All sera from healthy males had measurable hK2 concentrations (median, 402 ng/L). Almost all female sera had undetectable hK2. Serum hK2 and PSA in males correlated positively (r = 0.44), but hK2 was present at concentrations ∼2.5-fold lower than PSA. The PSA/hK2 ratio in male sera was 0.1–34, with a median of 2.6. In seminal plasma, this ratio was 100–500. More than 94% of immunoreactive hK2 in serum was in the free form (∼30 kDa); traces of hK2 complexed to α1-antichymotrypsin were present.
Conclusions: The limit of detection of the method for hK2 measurement described here (∼20-fold lower than any other reported assay for hK2) allows the generation of new clinical information. When combined with a previously described method for PSA measurement that has no cross-reactivity from hK2, this methods allows the relative proportions of hK2 and PSA in biological fluids to be measured.
Necessary Sample Size for Method Comparison Studies Based on Regression Analysis
Authors: Linnet Kristian 
Published: January 2020

Abstract
Background: In method comparison studies, it is of importance to assure that the presence of a difference of medical importance is detected. For a given difference, the necessary number of samples depends on the range of values and the analytical standard deviations of the methods involved. For typical examples, the present study evaluates the statistical power of least-squares and Deming regression analyses applied to the method comparison data.
Methods: Theoretical calculations and simulations were used to consider the statistical power for detection of slope deviations from unity and intercept deviations from zero. For situations with proportional analytical standard deviations, weighted forms of regression analysis were evaluated.
Results: In general, sample sizes of 40–100 samples conventionally used in method comparison studies often must be reconsidered. A main factor is the range of values, which should be as wide as possible for the given analyte. For a range ratio (maximum value divided by minimum value) of 2, 544 samples are required to detect one standardized slope deviation; the number of required samples decreases to 64 at a range ratio of 10 (proportional analytical error). For electrolytes having very narrow ranges of values, very large sample sizes usually are necessary. In case of proportional analytical error, application of a weighted approach is important to assure an efficient analysis; e.g., for a range ratio of 10, the weighted approach reduces the requirement of samples by &gt;50%.
Conclusions: Estimation of the necessary sample size for a method comparison study assures a valid result; either no difference is found or the existence of a relevant difference is confirmed.
Advances in Photoacoustic Noninvasive Glucose Testing
Authors: MacKenzie Hugh A , Ashton Helen S , Spiers Stephen , Shen Yaochun , Freeborn Scott S , Hannigan John , Lindberg John , Rae Peter 
Published: January 2020

AbstractWe report here on in vitro and in vivo experiments that are intended to explore the feasibility of photoacoustic spectroscopy as a tool for the noninvasive measurement of blood glucose. The in vivo results from oral glucose tests on eight subjects showed good correlation with clinical measurements but indicated that physiological factors and person-to-person variability are important. In vitro measurements showed that the sensitivity of the glucose measurement is unaffected by the presence of common blood analytes but that there can be substantial shifts in baseline values. The results indicate the need for spectroscopic data to develop algorithms for the detection of glucose in the presence of other analytes.
Noninvasive Prediction of Glucose by Near-Infrared Diffuse Reflectance Spectroscopy
Authors: Malin Stephen F , Ruchti Timothy L , Blank Thomas B , Thennadil Suresh N , Monfre Stephen L 
Published: January 2020

AbstractBackground: Self-monitoring of blood glucose by diabetics is crucial in the reduction of complications related to diabetes. Current monitoring techniques are invasive and painful, and discourage regular use. The aim of this study was to demonstrate the use of near-infrared (NIR) diffuse reflectance over the 1050–2450 nm wavelength range for noninvasive monitoring of blood glucose.Methods: Two approaches were used to develop calibration models for predicting the concentration of blood glucose. In the first approach, seven diabetic subjects were studied over a 35-day period with random collection of NIR spectra. Corresponding blood samples were collected for analyte analysis during the collection of each NIR spectrum. The second approach involved three nondiabetic subjects and the use of oral glucose tolerance tests (OGTTs) over multiple days to cause fluctuations in blood glucose concentrations. Twenty NIR spectra were collected over the 3.5-h test, with 16 corresponding blood specimens taken for analyte analysis.Results: Statistically valid calibration models were developed on three of the seven diabetic subjects. The mean standard error of prediction through cross-validation was 1.41 mmol/L (25 mg/dL). The results from the OGTT testing of three nondiabetic subjects yielded a mean standard error of calibration of 1.1 mmol/L (20 mg/dL). Validation of the calibration model with an independent test set produced a mean standard error of prediction equivalent to 1.03 mmol/L (19 mg/dL).Conclusions: These data provide preliminary evidence and allow cautious optimism that NIR diffuse reflectance spectroscopy using the 1050–2450 nm wavelength range can be used to predict blood glucose concentrations noninvasively. Substantial research is still required to validate whether this technology is a viable tool for long-term home diagnostic use by diabetics.
General Deming Regression for Estimating Systematic Bias and Its Confidence Interval in Method-Comparison Studies
Authors: Martin Robert F 
Published: January 2020

Abstract
Background: Various forms of least-squares regression analyses are used to estimate average systematic error (bias) and its confidence interval in method-comparison studies. When assumptions that underlie a particular regression method are inappropriate for the data, errors in estimated statistics result. In this report, I present an improved method for regression analysis that is free from the usual simplifying assumptions and is generally applicable to linearly related method-comparison data.
Methods: Theoretical equations based on the Deming approach, further developed by physicists and extended herein, were applied to method-comparison data analysis. Monte Carlo simulations were used to demonstrate the validity of the new procedure and to compare its performance to ordinary linear regression (OLR) and simple Deming regression (SDR) procedures.
Results: Simulation studies included three types of data commonly encountered in method-comparison studies: (a) constant within-method SDs for both methods, (b) constant within-method CVs for both methods, and (c) neither SDs nor CVs constant for both methods. For all cases examined, OLR produced unreliable confidence intervals of the estimated bias. However, OLR point estimates of systematic bias were reliable when the correlation coefficient was &gt;0.975. SDR produced reliable estimates of systematic bias for all cases studied, but the confidence intervals of systematic bias were unreliable when SDs of methods varied as a function of analyte concentration.
Conclusion: Only iteratively reweighted general Deming regression produced statistically unbiased estimates of systematic bias and reliable confidence intervals of bias for all cases.
Enzyme Immunoassay for Autoantibodies to Human Liver-Type Arginase and Its Clinical Application
Authors: Kimura Masahiro , Tatsumi Ke-Ita , Tada Hisato , Ikemoto Masaki , Fukuda Yoshihiro , Kaneko Akira , Kato Michio , Hidaka Yoh , Amino Nobuyuki 
Published: January 2020

AbstractBackground: Arginase is an enzyme of the urea cycle, and one of the two isoenzymes is the liver-type enzyme. We examined serum autoantibodies to this liver-type enzyme in patients with hepatitis.Methods: Antibodies to recombinant human liver-type arginase were measured by ELISA in 95 patients and 55 healthy controls.Results: The mean absorbance values in the ELISA assays of patients with definite autoimmune hepatitis (n = 11; P &lt;0.0001), probable autoimmune hepatitis (n = 31; P &lt;0.0001), and hepatitis C (HCV; n = 20; P &lt;0.01) were significantly different from those of healthy controls, but the values in patients with hepatitis B (HBV; n = 23) and other autoimmune diseases (n = 10) were not significantly different from those of healthy controls. When the cutoff was fixed at the upper 95th percentile of the absorbance value in healthy controls, positive reactions were found in 18.2%, 32.3%, 20.0%, 13.0%, and 10.0% of patients with definite autoimmune hepatitis, probable autoimmune hepatitis, HCV hepatitis, HBV hepatitis, and other autoimmune diseases, respectively. All of these positive reactions were abolished by inhibition of serum with recombinant antigen. The specificity and sensitivity of this ELISA were 96% and 29%, respectively. The intraassay and interassay coefficients of variation were 2.3–7.5% and 9.8–11%, respectively. There was no relationship between these antibodies and anti-nuclear, anti-smooth muscle, or anti-cytochrome P450IID6 antibodies.Conclusions: The ELISA for anti-liver-type arginase autoantibody improved the detectability of autoimmune hepatitis when compared with established assays for liver-specific autoantibodies.
Detection of Human Apolipoprotein E Genotypes by DNA Electrochemical Biosensor Coupled with PCR
Authors: Marrazza Giovanna , Chiti Giacomo , Mascini Marco , Anichini Mario 
Published: January 2020

AbstractBackground: Apolipoprotein E (apoE) is an important constituent of several plasma lipoproteins, mainly VLDL, HDL, and chylomicrons. It is involved in the redistribution of lipids in the liver and is implicated in growth and repair of injured neurons in the nervous system. apoE has also been associated with the risk of developing cardiovascular diseases and in familial type III hyperlipoproteinemia.Methods: We developed a new procedure for detecting genetic polymorphisms of apoE in human blood samples. The procedure is based on coupling of DNA electrochemical sensors with PCR-amplified DNA extracted from human blood. The DNA electrochemical sensor incorporated single-stranded oligonucleotides immobilized on graphite screen-printed electrodes (SPEs) by adsorption at controlled potential. The hybridization reaction on the electrode surface was monitored by chronopotentiometric stripping analysis (PSA), using daunomycin as indicator.Results: With use of two different probes, it was possible to investigate both DNA positions in which the apoE polymorphism takes place and thus to distinguish different genotypes. Real samples containing only complementary sequences gave a good increase in the area of the daunomycin peak (∼600 ms) compared with the peak observed with the buffer. Samples containing 50% complementary sequences gave a much lower increase, and samples containing only mismatch sequences gave a decrease in the daunomycin area. The procedure was validated by comparison with a method based on polyacrylamide gel electrophoresis.Conclusion: The coupling of DNA electrochemical sensors with PCR allowed quick discrimination between the different genotypes of apoE.
Measurement of Transcobalamin by ELISA
Authors: Nexo Ebba , Christensen Anna-Lisa , Petersen Torben E , Fedosov Sergey N 
Published: January 2020

AbstractBackground: Transcobalamin is essential for the cellular internalization of cobalamin. Methods to quantify the unsaturated protein are available, but few attempts have been made to develop methods to quantify the sum of unsaturated and cobalamin saturated transcobalamin.Methods: γ-Globulins from two polyclonal rabbit antibodies against recombinant human transcobalamin were used as capture and detection antibodies, and recombinant human transcobalamin was used as calibrator in an ELISA design.Results: The ELISA is specific for transcobalamin and has a detection limit of &lt;1.6 pmol/L. The imprecision (CV) is 4–6% for mean concentrations of 13–70 pmol/L. The central 95% interval for serum from healthy blood donors (n = 77) was ∼600-1500 pmol/L and showed limited variation with age and sex. No correlation was observed between the marker of acute phase reaction, C-reactive protein, and transcobalamin in plasma.Conclusions: The ELISA measures total transcobalamin in serum and thus can be used for measurement of transcobalamin in patients treated with cobalamin.
Comparison of Commercially Available 125I-based RIA Methods for the Determination of Circulating 25-Hydroxyvitamin D
Authors: Hollis Bruce W 
Published: January 2020

Abstract
Background: Measurement of circulating 25-hydroxyvitamin D [25(OH)D] is important in the management of metabolic bone disease. The aim of this study was to compare two widely used methods for the quantification of circulating 25(OH)D with attention to their abilities to measure 25-hydroxylated ergocalciferol (vitamin D2) [25(OH)D2] and cholecalciferol (vitamin D3) [25(OH)D3].
Methods: We used two commercially available, Food and Drug Administration-approved, radioiodine (125I)-based RIA kits for the detection of 25(OH)D (DiaSorin, Stillwater, MN and IDS Ltd, Tyne and Wear, United Kingdom). These methods were tested for general assay performance, including antibody specificity. Results were compared with those of an HPLC-based direct ultraviolet detection method.
Results: Within- and between-run CVs were ≤10%. Both methods quantitatively recovered 25(OH)D3 added to serum, but only the DiaSorin kit quantitatively recovered 25(OH)D2. The primary antibody in the IDS kit had unequal reactivities with pure 25(OH)D2 and 25(OH)D3, whereas the DiaSorin primary antibody reacted with them equally. In 50 patient samples assayed by HPLC, the IDS method, but not the DiaSorin method, underestimated total circulating 25(OH)D when significant circulating 25(OH)D2 was present in patient samples.
Conclusions: Some immunoassays may underestimate total 25(OH)D when 25(OH)D2 constitutes an appreciable part of the total.
Methylmalonic Acid Measured in Plasma and Urine by Stable-Isotope Dilution and Electrospray Tandem Mass Spectrometry
Authors: Magera Mark J , Helgeson Janice K , Matern Dietrich , Rinaldo Piero 
Published: January 2020

Abstract
Background: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization is robust and allows accurate measurement of both low- and high-molecular weight components of complex mixtures. We developed a LC-MS/MS method for the analysis of methylmalonic acid (MMA), a biochemical marker for inherited disorders of propionate metabolism and acquired vitamin B12 deficiency.
Methods: We added 1 nmol of the internal standard MMA-d3 to 500 μL of plasma or 100 μL of urine before solid-phase extraction. After elution with 18 mol/L formic acid, the eluate was evaporated, and butyl ester derivatives were prepared with 3 mol/L HCl in n-butanol at 65 °C for 15 min. For separation, we used a Supelcosil LC-18, 33 × 4.6 mm column with 60:40 (by volume) acetonitrile:aqueous formic acid (1 g/L) as mobile phase. The transitions m/z 231 to m/z 119 and m/z 234 to m/z 122 were used in the selected reaction monitoring mode for MMA and MMA-d3, respectively. The retention time of MMA was 2.2 min in a 3.0-min analysis, without interference of a physiologically more abundant isomer, succinic acid.
Results: Daily calibrations between 0.25 and 8.33 nmol in 0.5 mL exhibited consistent linearity and reproducibility. At a plasma concentration of 0.12 μmol/L, the signal-to-noise ratio for MMA was 40:1. The regression equation for our previous gas chromatography-mass spectrometry (GC-MS) method (y) and the LC-MS/MS method (x) was: y = 1.030x − 0.032 (Sy|x = 1.03 μmol/L; n = 106; r = 0.994). Inter- and intraassay CVs were 3.8–8.5% and 1.3–3.4%, respectively, at mean concentrations of 0.13, 0.25, 0.60, and 2.02 μmol/L. Mean recoveries of MMA added to plasma were 96.9% (0.25 μmol/L), 96.0% (0.60 μmol/L), and 94.8% (2.02 μmol/L). One MS/MS system used only overnight (7.5 h) replaced two GC-MS systems (30 instrument-hours/day) to run 100–150 samples per day, with reductions of total cost (supplies plus equipment), personnel, and instrument time of 59%, 14%, and 75%, respectively.
Conclusions: This method is well suited for large-scale MMA testing (≥100 samples per day) where a shorter analytical time is highly desirable. Reagents are less expensive than the anion-exchange/cyclohexanol-HCl method, and sample preparation of batches up to 100 specimens is completed in less than 8 h and is automated.
Defects in Pyrimidine Degradation Identified by HPLC-Electrospray Tandem Mass Spectrometry of Urine Specimens or Urine-soaked Filter Paper Strips
Authors: van Lenthe Henk , van Kuilenburg André B P , Ito Tetsuya , Bootsma Albert H , van Cruchten Arno , Wada Yoshiro , van Gennip Albert H 
Published: January 2020

Abstract
Background: Urinary concentrations of thymine, uracil, and their degradation products are useful indicators of deficiencies of enzymes of the pyrimidine degradation pathway. We describe a rapid, specific method to measure these concentrations to detect inborn errors of pyrimidine metabolism.
Methods: We used urine or urine-soaked filter-paper strips as samples and measured thymine, uracil, and their degradation products dihydrothymine, dihydrouracil, N-carbamyl-β-aminoisobutyric acid, and N-carbamyl-β-alanine. Reversed-phase HPLC was combined with electrospray ionization tandem mass spectrometry, and detection was performed by multiple-reaction monitoring. Stable-isotope-labeled reference compounds were used as internal standards.
Results: All pyrimidine degradation products could be measured in one analytical run of 15 min. Detection limits were 0.4–4 μmol/L. The intraassay imprecision (CV) of urine samples with added compounds was 1.3–12% for liquid urines and 1.0–10% for filter-paper extracts of the urines. The interassay imprecision (CV) was 3–11% (100–200 μmol/L). Recoveries were 89–99% at 100–200 μmol/L and 95–106% at 1 mmol/L in liquid urines, and 93–103% at 100–200 μmol/L and 100–106% at 1 mmol/L in filter-paper samples. Correct identifications of deficiencies of the pyrimidine-degrading enzymes were readily made with urine samples from patients with known defects.
Conclusions: HPLC with electrospray ionization tandem mass spectrometry allows rapid testing for disorders of the pyrimidine degradation pathway, and filter-paper samples allow easy collection, transport, and storage of urine samples.