bluuebunny/crossref_metadata_2025_split huggingface dataset:
Direct Enzyme Immunoassay of Estradiol in Serum of Women Enrolled in an in Vitro Fertilization and Embryo Transfer Program
Authors: Bouve J , De Boever J , Leyseele D , Bosmans E , Dubois P , Kohen F , Vandekerckhove D 
Published: January 2020

Abstract
We present a fast and simple direct enzyme immunoassay for the sexual steroid hormone estradiol-17 beta in serum of women enrolled in an in vitro fertilization and embryo transfer program. We added 25 microL of standards or samples and 125 microL of a mixture of monoclonal antibody and displacing agents to the wells of a microtiter plate previously coated with a second antibody. After 30 min 50 microL estradiol-horseradish peroxidase conjugate is added. Total incubation time is 75 min. The immunoassay is stopped by washing the microtiter plate. The amount of bound conjugate is then measured at 450 nm with hydrogen peroxide as a substrate and 3,3',5,5'-tetramethylbenzidine as chromogen. The detection limit is 0.24 nmol/L. The assay is thus limited in its application. Analytical recovery is 90.8% (range 80.4-102.9%); within- and between-assay CVs range between 1.3% and 15.4%. Total assay time, including preparation of reagents and data reduction, is only 2.5 h. Results of this enzyme immunoassay compare well with those obtained with four different commercial radioimmunoassays (r = 0.88-0.93).
ROC Curve Analysis: An Example Showing the Relationships Among Serum Lipid and Apolipoprotein Concentrations in Identifying Patients with Coronary Artery Disease
Authors: Zweig M H , Broste S K , Reinhart R A 
Published: January 2020

Abstract
Clinical accuracy, defined as the ability to discriminate between states of health, is the fundamental property of any diagnostic test or system. It is readily expressed as clinical sensitivity and specificity, and elegantly represented by the receiver operating characteristic (ROC) curve. To demonstrate the use of ROC curves, we reexamine a study of the ability of serum lipid and apolipoprotein measures to discriminate among degrees of coronary artery disease in patients undergoing coronary angiography. ROC curve analysis reveals that none of these indexes is highly accurate, but demonstrates a modest increase in the accuracy of apolipoprotein over lipid indexes.
Assessment of Urea and Other Uremic Markers for Quantification of Dialysis Efficacy
Authors: Vanholder R C , De Smet R V , Ringoir S M 
Published: January 2020

Abstract
To validate azotemic markers as an index for intradialytic changes in solute concentration, we compared eight solutes (pseudouridine, xanthine, hypoxanthine, peak 4, peak 5, p-hydroxyhippuric acid, indoxyl sulfate, and hippuric acid) with five classical azotemic markers (urea, creatinine, uric acid, phosphate, and potassium). We determined concentrations by reversed-phase HPLC coupled to ultraviolet absorption or photometrically. Seven compounds showed significant intercorrelation (P less than 10(-5)): urea, pseudouridine, uric acid, peaks 4 and 5, p-hydroxyhippuric acid, and creatinine. The hippuric acid concentration change after dialysis correlated with the change for these seven compounds and also with indoxyl sulfate, hypoxanthine, potassium, and the group of unidentified ultraviolet-absorbing HPLC peaks accumulating in uremia. We conclude that urea only partially represents the concentration changes of other retention compounds after dialysis; alternative markers, e.g., hippurate, should be considered.
Macroamylases: Differences in Activity Against Various-Size Substrates
Authors: Rosenblum J L , Hortin G L , Smith C H , Pashos G E , Landt M 
Published: January 2020

Abstract
Hyperamylasemia caused by macroamylases can lead to the overdiagnosis of acute pancreatitis. We examined whether interference from macroamylase is less in assays that use high-molecular-weight rather than oligosaccharide substrates. We hypothesized that high-molecular-weight substrates would be sterically excluded from macroamylasemic complexes and thus would be hydrolyzed less efficiently. Eighteen macroamylasemic samples were assayed by using red-dyed amylopectin or blue-dyed starch as polysaccharide substrates or by using maltoheptaose or maltotetraose as oligosaccharide substrates. The oligosaccharide substrates gave comparable results (y = 0.81x + 83); we observed consistently lower activities for amylopectin than for maltotetraose (y = 0.32x + 38). We observed no bias among methods when nonmacroamylasemic specimens were analyzed. The mechanism of this difference was examined by adding anti-human pancreatic amylase antibodies to hyperamylasemic serum samples from patients without macroamylasemia and purified human pancreatic or salivary isoamylases. In each case, polyclonal and monoclonal antibodies lowered amylase activity more in assays with complex polysaccharides than in those with oligosaccharides. The use of high-molecular-weight substrates diminishes interference, and detection of suspected macroamylasemia may be possible through comparison of activities determined from automated methods that use different substrates.
Frozen Human Serum Reference Material for Standardization of Sodium and Potassium Measurements in Serum or Plasma by Ion-Selective Electrode Analyzers
Authors: Gunaratna P C , Koch W F , Paule R C , Cormier A D , D'Orazio P , Greenberg N , O'Connell K M , Malenfant A , Okorodudu A O , Miller R 
Published: January 2020

Abstract
Three interlaboratory round-robin studies (RR1, RR2, and RR3) were conducted to identify a serum-based reference material that would aid in the standardization of direct ion-selective electrode (ISE) measurements of sodium and potassium. Ultrafiltered frozen serum reference materials requiring no reconstitution reduced between-laboratory variability (the largest source of imprecision) more than did other reference materials. ISE values for RR3 were normalized by the use of two points at the extremes of the clinical range for sodium (i.e., 120 and 160 mmol/L), with values assigned by the flame atomic emission spectrometry (FAES) Reference Method. This FAES normalization of ISE raw values remarkably improved all sources of variability and unified the results from seven different direct ISE analyzers to the FAES Reference Method value. Subsequently, a three-tiered, fresh-frozen human serum reference material was produced to the specifications developed in RR1-RR3, was assigned certified values for sodium and potassium by Definitive Methods at the National Institute of Standards and Technology (NIST), and was made available in 1990 to the clinical laboratory community as a Standard Reference Material (SRM); it is now identified as SRM 956. Albeit retrospectively, we show how applying an FAES normalization step identical to that used in RR4/5 to the ISE data for SRM 956 after the NIST Definitive Method values were known, consistently moved the ISE results for RR3 closer to the true value for Na+ and K+.
HemoCue: Evaluation of a Portable Photometric System for Determining Glucose in Whole Blood
Authors: Ashworth L , Gibb I , Alberti K G 
Published: January 2020

Abstract
We assessed the HemoCue system for measuring glucose in 5 microL of whole blood. A glucose dehydrogenase-based reaction is used with dried reagents contained in disposable microcuvettes, which are filled with blood by capillary action. Automated hexokinase and YSI 23AM glucose analyzer methods were used for comparison. Overall imprecision (CV) was better than 4.5%, with no significant differences in results between three different HemoCue photometers and four batches of microcuvettes. Regression slopes (+/- SE) were 0.947 (0.011) with the YSI and 0.966 (0.015) with the hexokinase method. Analytical recovery of added glucose was 101-106%, and the system functioned with hematocrits up to 0.65. Bilirubin up to 453 mumol/L did not interfere, but high concentrations of endogenous (greater than 3 mmol/L) and exogenous triglycerides gave positive interference. The system proved stable and robust under a wide range of storage and handling conditions; performance was impaired only at high ambient temperature (37 degrees C). We conclude that the HemoCue system should prove useful for glucose measurement; further testing outside the laboratory is warranted.
Intact Parathyroid Hormone: Performance and Clinical Utility of an Automated Assay Based on High-Performance Immunoaffinity Chromatography and Chemiluminescence Detection
Authors: Hage D S , Taylor B , Kao P C 
Published: January 2020

Abstract
The performance and clinical utility of an automated assay of intact parathyroid hormone (parathyrin, PTH) are evaluated. The method is based on the extraction of PTH from plasma by an HPLC column containing immobilized anti-(44-68 PTH) antibodies. The PTH retained is detected with a postcolumn reactor and use of anti-(1-34 PTH) chemiluminescent-labeled antibodies. The total cycle time of the assay is 6.5 min per injection after a 1-h incubation. The lower limit of detection for PTH in a 66-microL plasma sample was 0.5 pmol/L based on peak heights and 0.2 pmol/L based on peak areas. Mean analytical recovery for PTH added to plasma was 97%. The within-day precisions (CVs) for 4.2 and 30 pmol/L PTH plasma samples were 9.2% and 5.6% and the day-to-day precisions were 10.3% and 5.7%, respectively. No significant interferences from 1-34, 44-68, or 53-84 PTH fragments were noted, even at highly increased concentrations of fragments. The correlation of results with those of a manual assay of intact PTH was 0.97, and the results showed good agreement with disease state for patients with hypo- or hyperparathyroidism. The specificity of the assay for primary hyperparathyroidism was greater than 95%. We discuss the advantages (speed and quality control) of this approach over current immunoassays and the potential use of this method for detecting other analytes.
Ciliated Enteric Duplication Cyst Presenting as A Pancreatic Cystic Neoplasm: Report of A Case with Cyst Fluid Analysis
Authors: Pins M R , Compton C C , Southern J F , Rattner D W , Lewandrowski K B 
Published: January 2020

Abstract
Pancreatic cysts include inflammatory pseudocysts, cystic tumors (serous and mucinous), and various rare cystic lesions. We report a case of a ciliated enteric duplication cyst that presented on computed tomographic scan as a pancreatic cystic neoplasm. Cyst fluid analysis revealed markedly increased concentrations of carcinoembryonic antigen and CA 125 and increased fluid viscosity. These features are typical for a mucinous cystic neoplasm of the pancreas and demonstrate a potential pitfall associated with the diagnosis of pancreatic cysts by chemical analyses. Enteric duplications involving the pancreas are rare, usually of gastric origin, and usually communicate with their enteric source. Morphological and histochemical analysis suggest that this cyst was of caudal foregut origin. This is the first reported case of a ciliated foregut cyst involving the pancreas. The chemical characteristics of the cyst fluid of these lesions have not been described previously.
Progress Toward the Development of an Implantable Sensor for Glucose
Authors: Wilson G S , Zhang Y , Reach G , Moatti-Sirat D , Poitout V , Thévenot D R , Lemonnier F , Klein J C 
Published: January 2020

Abstract
The development of an electrochemically based implantable sensor for glucose is described. The sensor is needle-shaped, about the size of a 28-gauge needle. It is flexible and must be implanted subcutaneously by using a 21-gauge catheter, which is then removed. When combined with a monitoring unit, this device, based on the glucose oxidase-catalyzed oxidation of glucose, reliably monitors glucose concentrations for as long as 10 days in rats. Various design considerations, including the decision to monitor the hydrogen peroxide produced in the enzymatic reaction, are discussed. Glucose constitutes the most important future target analyte for continuous monitoring, but the basic methodology developed for glucose could be applied to several other analytes such as lactate or ascorbate. The success in implementation of such a device depends on a reaction of the tissue surrounding the implant so as not to interfere with the proper functioning of the sensor. Histochemical evidence indicates that the tissue response leads to enhanced sensor performance.
Portable Simultaneous Multiple Analyte Whole-Blood Analyzer for Point-of-Care Testing
Authors: Schembri C T , Ostoich V , Lingane P J , Burd T L , Buhl S N 
Published: January 2020

Abstract
We describe a portable clinical chemistry analyzer for point-of-care measurements of multiple analytes in less than 10 min from approximately 40 microL of whole blood (fingerstick or venous). Whole blood is applied directly to a 7.9-cm-diameter, single-use plastic rotor containing liquid diluent and greater than or equal to 4-12 tests in the form of 1- to 2-mm-diameter dry reagent beads. The reagent/rotor is immediately placed in a portable instrument along with a ticket/label results card. As the instrument spins the rotor, capillary and rotational forces process the blood into diluted plasma, distribute the patient's diluted sample to cuvettes containing the reagent beads, and mix the diluted sample with the reagents. The instrument monitors the chemical reactions optically at nine wavelengths; sample volume and temperature are also measured optically. The calibration data for each reagent are read from a bar code on the periphery of each rotor. The instrument processes all the measurements to calculate, store, print, and communicate the results. Each reagent/rotor contains an enzymatic control that must be within a defined range before the results from that analysis are reported.
Eliminating Interference from Heterophilic Antibodies in a Two-Site Immunoassay for Creatine Kinase Mb by Using F(ab')2 Conjugate and Polyclonal Mouse IgG
Authors: Vaidya H C , Beatty B G 
Published: January 2020

Abstract
Heterophilic antibodies interfere in two-site immunoassays. Our purpose was to screen for the samples containing heterophilic antibodies that react with mouse immunoglobulins and to use them to determine how to eliminate interference in various two-site immunoassays being developed in our laboratory. Of approximately 2600 samples screened, 81 had heterophilic antibodies. When creatine kinase MB (CKMB) concentration was measured with intact antibody conjugate in these 81 samples, 18 (22%) samples had apparent CKMB values significantly greater than values measured with Hybritech's "Tandem -E CKMB immunoenzymetric" assay and Corning agarose-gel electrophoresis. Adding up to 133 mg/L of polymerized IgG or up to 1666 mg/L polyclonal mouse IgG in the assay did not eliminate the interference in all the samples. However, adding F(ab')2 conjugate plus 40 mg/L of polymerized IgG or 83 mg/L of polyclonal mouse IgG eliminated the interference in all the samples. This approach was also effective in eliminating the interference in 15 samples containing 4.7-165.2 mg/L of human antimouse antibody (HAMA). Combined use of F(ab')2 conjugate and polyclonal mouse IgG is recommended to eliminate interference from heterophilic antibodies that react with murine immunoglobulins or HAMA in two-site murine-antibody-based assays.
Assay of Endopeptidase-24.11 Activity in Plasma Applied to In Vivo Studies of Endopeptidase Inhibitors
Authors: Yandle T , Richards M , Smith M , Charles C , Livesey J , Espiner E 
Published: January 2020

Abstract
We developed a fluorometric assay for endopeptidase-24.11 (EC 3.4.24.11) in human plasma. Substrate [glutaryl-Ala-Ala-Phe-amidomethylcoumarin(AMC)] was incubated with plasma (20 microL, 30 min, pH 7.6) with (control) or without the endopeptidase-24.11 inhibitor phosphoramidon. Further incubation with aminopeptidase M released free AMC. Within-assay CVs were 4.5% and 8.6%, respectively, at 3.31 and 0.27 nmol of AMC released per milliliter per minute. The between-assay CV was 10.4% at 0.31 nmol/mL per minute and the detection limit was 0.05 nmol/mL per minute. A highly skewed distribution of endopeptidase-24.11 in 41 normal samples was found, ranging from 0.12 to 6.84 nmol/mL per minute (median = 0.44). Mean endopeptidase-24.11 concentrations were significantly higher in hypertensive subjects (0.68 nmol/mL per minute) than in normotensive subjects (0.34 nmol/mL per minute; P less than 0.05). Compared with placebo administration, the oral endopeptidase-24.11 inhibitor UK 79300 significantly inhibited the plasma enzyme at doses of 100 mg (twice daily). Although in normotensive subjects the enzyme was unaffected with doses of 25 mg, the same dose (25 mg) inhibited the plasma enzyme in hypertensive subjects. No activity was detected in sheep plasma, but addition of exogenous endopeptidase-24.11 to sheep plasma in vitro allowed in vivo assessment of the effect of infused endopeptidase-24.11 inhibitor SCH 39370.
Identification of the Steroids in Neonatal Plasma that Interfere with 17 Alpha-Hydroxyprogesterone Radioimmunoassays
Authors: Wong T , Shackleton C H , Covey T R , Ellis G 
Published: January 2020

Abstract
Neonatal plasma contains interferents that increase the apparent 17 alpha-hydroxyprogesterone (17-OHP) content measured by direct (no-extraction) radioimmunoassay. We fractionated extracts from neonatal plasma pools by liquid chromatography with a Sephadex LH-20 column and measured 17-OHP immunoreactivity by a direct test kit. We found immunoreactivity in the free steroid and glucuronide fraction and also in the monosulfate fraction. We analyzed these two fractions by reversed-phase high-performance liquid chromatography (HPLC) and HPLC-mass spectrometry. We collected fractions and assayed for 17-OHP immunoreactivity. The HPLC fractions containing the interfering steroid monosulfates were analyzed by ion-spray mass spectrometry and, after solvolysis, by gas chromatography-mass spectrometry. Several monosulfates were identified, including those of 17 alpha-hydroxy-pregnenolone, 16 alpha-hydroxypregnenolone, pregnenolone, and several pregnenetriols. 17 alpha-Hydroxypregnenolone sulfate was the most significant interferent. Other commercially available 17-OHP assays showed similar interference when used without an extraction step. Kit manufacturers should select antibodies and protocols to minimize cross-reaction with sulfates, especially 17 alpha-hydroxypregnenolone sulfate.
Comparison of Assay Kits for Unconjugated Estriol Shows that Expressing Results as Multiples of the Median Causes Unacceptable Variation in Calculated Risk Factors for Down Syndrome
Authors: Reynolds T , John R 
Published: January 2020

Abstract
We compared the performance of two methods for assaying unconjugated estriol in serum: the modified Amerlex third-trimester RIA kit, as used in seminal papers on unconjugated estriol in Down syndrome screening, and the new optimized Amerlex-M second-trimester kit. The significant difference between the results of each assay could cause unacceptable changes in the detection rate and false-positive rate of Down syndrome screening programs, especially if previously published values for estriol are used in the risk calculation. It is not possible to define new calculation parameters for every assay kit because new parameters will need to be defined every time kit changes occur, which would require a large collection of samples from Down syndrome pregnancies for standardization. Possible solutions to this problem are discussed.
Nonradioactive Quantification of Low Concentrations of Hemoglobin a by HPLC for Midtrimester Prenatal Diagnosis of β-Thalassemia
Authors: Maiavacca R , Tedeschi S , Mosca A , Calmi S , De Leonardis P , Todaro C , Zuliani G , Buscaglia M , Cantù-Rajnoldi A 
Published: January 2020

Abstract
The usual methods for prenatal diagnosis of beta-thalassemia and other hemoglobinopathies by assay of fetal blood erythrocytes are either complex (analysis of globin chains synthesis by carboxymethylcellulose chromatography) or only semiquantitative [isoelectric focusing of hemoglobin (Hb)]. To further simplify the diagnostic procedure and to obtain quantitative data, we measured the small concentrations of Hb A in fetal erythrocytes by using a high-pressure liquid chromatography (HPLC) instrument (DIAMAT-TM; Bio-Rad) equipped with the new column proposed for measuring Hb A2. We analyzed 212 uncontaminated fetal blood samples obtained by cordocentesis between the 18th and 22nd weeks of pregnancy, using the HPLC procedure, and compared the results with those obtained by the above-named methods. The Hb A values obtained ranged between 0% and 8.5%; they were less than or equal to 1.8% in 44 fetuses affected by homozygous beta-thalassemia and greater than 2.5% in 168 unaffected fetuses. The method was simple, rapid, and reproducible (CV 3.2%) and there was good correlation between Hb A concentrations determined by HPLC and the beta/gamma ratio determined by carboxymethylcellulose chromatography (r = 0.7687; P less than 0.0001). No false-negative or false-positive results were observed, and there was no overlap of values between affected and unaffected fetuses.
Medical-care systems for long-duration space missions
Authors: Houtchens B A 
Published: January 2020

Abstract
As in the opening of frontiers on Earth, human physiological maladaptation, illness, and injury--rather than defective transportation systems--are likely to be the pace-limiting variables in efforts to expand the presence of humans into the solar system. Because of the inability of individuals to return to Earth rapidly and conveniently, the capability of delivering medical care on site will be key to the success of a manned space station, lunar base, and Mars mission. Spaceflight medical care equipment must meet stringent constraints of size, weight, and power requirements, and then must function accurately in remote, self-contained, microgravity settings after extended intervals of storage, with neither expert operators nor repair technicians on site. Satisfying these unusually rigorous requirements will require sustained direct involvement of clinically up-to-date health-care providers, medical scientists, and biomedical engineers, as well as astronauts and aerospace engineers and managers. Solutions will require validation in clinical settings with real patients, as well as in simulated operational settings.
The clinical chemistry and immunology of long-duration space missions
Authors: Wu A H , Taylor G R , Graham G A , McKinley B A 
Published: January 2020

Abstract
Clinical laboratory diagnostic capabilities are needed to guide health and medical care of astronauts during long-duration space missions. Clinical laboratory diagnostics, as defined for medical care on Earth, offers a model for space capabilities. Interpretation of laboratory results for health and medical care of humans in space requires knowledge of specific physiological adaptations that occur, primarily because of the absence of gravity, and how these adaptations affect reference values. Limited data from American and Russian missions have indicated shifts of intra- and extracellular fluids and electrolytes, changes in hormone concentrations related to fluid shifts and stresses of the missions, reductions in bone and muscle mass, and a blunting of the cellular immune response. These changes could increase susceptibility to space-related illness or injury during a mission and after return to Earth. We review physiological adaptations and the risk of medical problems that occur during space missions. We describe the need for laboratory diagnostics as a part of health and medical care in space, and how this capability might be delivered.