bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heterologous double-determinant immunoradiometric assay CA 125 II: reliable second-generation immunoassay for determining CA 125 in serum
Authors: Kenemans P , van Kamp G J , Oehr P , Verstraeten R A 
Published: January 2020

Abstract
The new CA 125 II (Centocor) serum assay utilizing the M11 mouse monoclonal antibody as capture antibody and OC125 as tracer antibody, was investigated for its technical and clinical performance against the original CA 125 assay. The CA 125 II test revealed a quadruple increase in signal-to-noise ratio, good intra- and interassay precision (with CVs &lt; 5% and 7%, respectively), improved dilution linearity, and a minimal detectable dose of 0.38 units/mL. Sera were obtained from healthy females (n = 192), women with benign conditions (n = 208), and patients with various cancers (n = 379). Both assays measured highly similar CA 125 distributions with equal reference ranges and nearly identical positivity (&gt; 35 units/mL) rates, resulting in similar receiver-operating characteristic curves and monitoring graphs. Linear regression analysis of results by the two assays (CA 125 = x, CA 125 II = y) in ovarian cancer patients showed, for CA 125 assay values between 0 and 1000 units/mL, a slope of 1.00 and a y-intercept of 12.6 (n = 254, r = 0.8617, P &lt; 0.0001). The heterologous CA 125 II assay appeared to be more accurate in patients who had human anti-mouse antibodies after immunoscintigraphy. The CA 125 II immunoradiometric assay is sensitive and reliable for measuring serum CA 125, and fully retains the cutoff values of 35 and 65 units/mL that were defined with the original CA 125 immunoradiometric assay.
Prostate-specific antigen: biochemistry, analytical methods, and clinical application
Authors: Armbruster D A 
Published: January 2020

Abstract
Prostate-specific antigen (PSA) is a glycoprotein produced exclusively by prostatic tissue. PSA's absolute tissue specificity makes it valuable as a forensic marker and, more important, as a tumor marker for prostatic cancer. Prostatic cancer is prevalent in the older male population and is a major cause of death in men. Previously, prostatic acid phosphatase (PAP) was used to help diagnose and monitor the efficacy of therapy for prostate cancer. PAP has now been displaced by PSA, which has greater clinical sensitivity even though it has less clinical specificity. PSA is useful for monitoring therapy, particularly surgical prostatectomy, because complete removal of the prostate gland should result in PSA being undetectable. Measurable PSA after radical prostatectomy indicates residual prostatic tissue or metastasis, and increasing PSA concentrations indicate recurrent disease. PSA is also useful for screening selected populations of patients with symptoms indicative of prostate cancer; its use for general screening is debatable because of its less-than-optimal specificity, the cost of unselected screening, and the lack of evidence that early detection of prostate cancer decreases morbidity and mortality. Distinguishing between patients with prostatic cancer and those with benign prostatic hypertrophy is particularly difficult because of the overlap in PSA values in the two groups. Determining the rate of change in PSA per year from serial measurements or calculating the ratio of PSA per volume of the prostate gland may allow these two groups to be more readily differentiated.
Isocratic HPLC assay with electrochemical detection of free gamma-aminobutyric acid in cerebrospinal fluid
Authors: Naini A B , Vontzalidou E , Côté L J 
Published: January 2020

Abstract
A method for measuring gamma-aminobutyric acid (GABA) in human cerebrospinal fluid (CSF) by isocratic HPLC with electrochemical detection is described. The method is based on precolumn derivatization of GABA with o-phthaldialdehyde (OPA) and tert-butylthiol (t-BT), separation of the GABA-OPA complex on a reversed-phase column, and quantitation by means of a Coulochem electrochemical detector. The method is highly sensitive and specific for GABA. In three samples of human CSF containing low, medium, and high amounts of GABA, the coefficients of variation between and within runs were 4.5% and 3.6%, respectively. The concentration of GABA in 10 neurologically intact subjects was 92.5 +/- 9.4 nmol/L of CSF.
Multicenter evaluation of Reflotron direct dry-chemistry assay of high-density lipoprotein cholesterol in venous and fingerstick specimens
Authors: Warnick G R , Boerma G J , Assmann G , Endler A T , Gerique G , Gotto A M , Graziani M S , Lippi U , Patsch W , Riesen W F 
Published: January 2020

Abstract
The Reflotron HDL Cholesterol test (Boehringer Mannheim GmbH) directly separates and analyzes high-density lipoprotein (HDL) cholesterol in plasma collected with EDTA in an integrated dry-reagent system suitable for alternative site testing of lipoproteins. We describe a multicenter evaluation of this test by two US and six European laboratories experienced in lipid analysis. Each laboratory compared the Reflotron with the same conventional wet-chemistry method, Boehringer phosphotungstate-Mg2+ precipitation with enzymatic cholesterol assay. Imprecision was within accepted guidelines, with CVs of &lt; or = 8% for fresh and frozen plasmas (median CV 1.7-3.9%) and for lyophilized sera (median CV 3.8-4.7%), similar to those of the conventional method. Results of linear-regression analysis were as follows: Reflotron HDL Cholesterol = 1.03 conventional - 3.9 mg/L, r = 0.987. The Reflotron results were somewhat low in the two US laboratories, demonstrating the need for general standardization of methods for measuring HDL cholesterol. Results from capillary fingerstick plasma agreed well with those from venous-derived plasma; capillary = 1.04 venous + 4.5 mg/L, r = 0.967. The system is relatively insensitive to interference from hemoglobin (&lt; or = 0.75 g/L), ascorbic acid (&lt; or = 0.3 g/L), bilirubin (&lt; or = 50 mg/L), cholesterol (&lt; or = 3.5 g/L), and triglycerides (&lt; or = 4 g/L). The relative ease of operation and the rapid availability of results (within 90 s for plasma collected in EDTA) make the method appropriate for use by well-trained, but not necessarily technical, operators in the physician's office or other alternative sites.
Discrimination of human T-lymphotropic virus type-I and type-II infections by synthetic peptides representing structural epitopes from the envelope glycoproteins
Authors: Rudolph D L , Lal R B 
Published: January 2020

Abstract
Synthetic peptides representing the immunodominant structural motifs of the envelope region of human T-lymphotropic virus types I (HTLV-I) (Env-1(191-214) and Env-5(242-257)) and II (HTLV-II) (Env-20(85-102 and Env-2(187-209)) were used to develop an enzyme immunoassay that could discriminate between HTLV-I and HTLV-II. Serum specimens from individuals whose infections were confirmed and typed by means of the polymerase chain reaction (PCR) were used to determine the sensitivity and specificity of the new assay. When 73 PCR-confirmed HTLV-I specimens were tested with the HTLV-I peptides, the absorbance values for 71 (97.3%) were at least two times higher than the values obtained with the HTLV-II peptides; these samples thus were classified as HTLV-I. Two specimens reacted with all the peptides and, therefore, could not be typed. Conversely, when 59 PCR-confirmed HTLV-II specimens were tested with the HTLV-II peptides, 55 (93%) produced high absorbance values and were typed as HTLV-II; 4 specimens could not be typed. None of the specimens was incorrectly typed; hence, the specificity of this assay was 100%. When this assay was compared with other HTLV immunoassays, the degrees of sensitivity and specificity were similar. The main advantage of this new assay is that synthetic peptides representing variant sequences can easily be added as new variant HTLV strains are identified.
Programming events in the regulation of cell proliferation and death
Authors: Berges R , Isaacs J T 
Published: January 2020

Abstract
In developing new and more successful therapies for preventing and treating cancer, it is critical to understand what normally regulates cell proliferation and cell death and what are the specific dysfunctions associated with these regulations in individual cancers. Here we review the programmed series of molecular, cellular, and biochemical events required for a cell's entrance and progression through the proliferative vs death processes as a starting point for such approaches to new therapies.
Application of simple chromatographic methods for the diagnosis of defects in pyrimidine degradation
Authors: van Gennip A H , Busch S , Elzinga L , Stroomer A E , van Cruchten A , Scholten E G , Abeling N G 
Published: January 2020

Abstract
Recent findings suggest that inborn errors of pyrimidine catabolism are less rare than generally assumed. We propose a complete set of diagnostic methods for these disorders, suitable for the clinical chemistry laboratory, and present relevant reference data. Applications of thin-layer chromatography, high-performance liquid chromatography, and conventional cation-exchange amino acid analysis lead to detection of various defects in pyrimidine degradation, including the recently described deficiencies of dihydropyrimidine dehydrogenase and dihydropyrimidinase. We also illustrate the potential of the methods to analyze for the catabolites expected to be increased in the urine of patients with ureidopropionase deficiency. Possible pitfalls in the diagnosis and ways to prevent misdiagnosis are demonstrated. The methods offer possibilities for clinical chemistry laboratories to extend their diagnostic capacity to the new area of pyrimidine degradation defects.
Measurement of deoxyribonuclease I activity in human tissues and body fluids by a single radial enzyme-diffusion method
Authors: Nadano D , Yasuda T , Kishi K 
Published: January 2020

Abstract
In the single radial enzyme-diffusion (SRED) method for assay of deoxyribonuclease I, a precisely measured volume of the enzyme solution is dispensed into a circular well in an agarose gel layer in which DNA and ethidium bromide are uniformly distributed. A circular dark zone is formed as the enzyme diffuses from the well radially into the gel and digests substrate DNA. The diameter of the dark circle of hydrolyzed DNA increases in size with time and correlates linearly with the amount of enzyme applied to the well. Thus, the SRED can be used for quantitation of deoxyribonuclease I with a limit of detection of 2 x 10(-6) unit. This corresponds to 1 pg of purified urine deoxyribonuclease I. We measured the deoxyribonuclease I activity of 17 different human tissues and body fluids from healthy donors. Urine samples showed the greatest activity, 6.0 +/- 2.2 kilo-units/g protein (mean +/- SD). Serum deoxyribonuclease I activity was 4.4 +/- 1.8 units/L.
Preparative chromatographic purification of cyclosporine metabolites
Authors: Brooks C A , Cramer S M , Rosano T G 
Published: January 2020

Abstract
Polar and primary metabolites of cyclosporin A (CsA) have successfully been isolated by a novel separation protocol. An efficient, easy-to-scale-up chromatographic adsorption/desorption operation recovers polar and primary CsA metabolite pools from large volumes of urine; purified CsA metabolites are subsequently obtained by high-resolution preparative elution chromatography of the semipurified metabolite pools. Separations performed on a semipreparative scale [with a 250 x 9.4 mm (i.d.) reversed-phase HPLC column] yielded microgram quantities of CsA metabolites at &gt; 97% purity, as determined by fast atom bombardment mass spectrometry. These separations also yielded two previously unreported CsA metabolites, similar to AM1A but with an additional hydroxylation. The yield of metabolites was increased to several milligrams by performing the separations with a preparative-scale [250 x 21.2 mm (i.d.)] reversed-phase column. The production rate of purified primary CsA metabolites was greatly increased by performing the separation with the preparative-scale column under conditions of severe mass overloading. In a single chromatographic run, we successfully isolated 11.0 and 5.0 mg of AM1 and AM1c, respectively, at a purity of &gt; 97%. As expected, this increase in the yield of purified metabolites was accompanied by a decrease in the overall recovery. This separation scheme enables the rapid processing of large volumes of urine for isolation of the milligram quantities of CsA metabolites necessary to assess their biological activity. The procedure is applicable to small- or large-scale metabolite isolation and provides a ready source of purified metabolites for in vitro and whole-animal studies.
Characteristics and clinical application of a radiometric Escherichia coli-based phospholipase A2 assay modified for serum analysis
Authors: Aufenanger J , Zimmer W , Kattermann R 
Published: January 2020

Abstract
Determination of activities of phospholipase A2 (PLA2) in human sera was based on the hydrolysis of phospholipids from [1-14C]oleic acid-labeled Escherichia coli biomembranes. The E. coli membranes served as substrate specifically for the PLA2 of human serum and were essentially resistant to other lipases in human sera, i.e., lipoprotein lipases, hepatic triacylglycerolipase, or pancreatic lipase in acute pancreatitis. Exchange of phospholipids between the serum and the biomembrane compartment aggravates the determination of PLA2 activity in human serum, which is naturally rich in phospholipids. In our modified E. coli assay, which overcomes these difficulties, the main substrate components phosphatidylethanolamine (70%) and cardiolipin (25%) were &gt; 90% labeled in the sn-2 position. Fatty acids released by PLA2 activity were eluted from an aminopropyl solid-phase column directly into scintillation vials, where the radioactivity was counted. The ratio of [1-14C]oleic acid to released total fatty acids was used to calculate true enzymatic activity. The linear assay range extended from 0 to 3.6 U/L (0-60 nkat/L), with a detection limit of &lt; 0.03 U/L (&lt; 0.5 nkat/L). Within-assay imprecision (CV) was &lt; 6% and between-assay is &lt; 10% over the whole activity range. The normal range for men was 0-0.44 U/L (0-7.33 nkat/L) and for women 0.044-1.11 U/L (0.73-18.4 nkat/L). Patients with septicemia, pancreatitis, acute respiratory distress syndrome, or other severe diseases had PLA2 values up to 540 U/L (9000 nkat/L).
One-step competitive immunochromatographic assay for semiquantitative determination of lipoprotein(a) in plasma
Authors: Lou S C , Patel C , Ching S , Gordon J 
Published: January 2020

Abstract
Numerous studies have associated high concentrations of lipoprotein(a) [Lp(a)] with atherosclerosis. We developed a rapid, one-step competitive immunochromatographic assay to measure Lp(a) in plasma. The assay is performed on a nitrocellulose membrane strip and the result is determined by a visual readout of rust-colored colloidal selenium. The assay is based on the principle that Lp(a) in the sample will compete with Lp(a)-coated colloidal selenium for binding to the anti-Lp(a) monoclonal antibody immobilized on the assay strip in the format of four ladder bars. The number of capture bars that appear as a result of the formation of colloidal selenium color is proportional to the concentration of the Lp(a) protein in the samples. The strip assay semiquantitatively measures Lp(a) concentrations ranging from 0 to 180 mg/L of Lp(a) protein in serum, plasma, or fingerstick whole-blood samples. This assay appears very useful for quick identification of individuals with above-normal concentrations of plasma Lp(a) protein (&gt; 70 mg/L), and has potential for monitoring a patient's response to treatment with Lp(a)-lowering drugs.
Radioimmunoassay for the pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen: a new serum marker of bone collagen degradation
Authors: Risteli J , Elomaa I , Niemi S , Novamo A , Risteli L 
Published: January 2020

Abstract
We developed a radioimmunoassay (RIA) for the carboxy-terminal telopeptides of type I collagen (ICTP), cross-linked with the helical domain of another type I collagen molecule, after isolation from human femoral bone. The cross-linked peptide was liberated by digesting insoluble, denatured bone collagen either with bacterial collagenase or with trypsin, and purified by two successive reversed-phase separations on HPLC, with monitoring of pyridinoline-specific fluorescence. The purity of the peptide was verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its origin in the type I collagen fibers was determined by amino-terminal amino acid sequencing. Polyclonal antibodies and a separation reagent containing second antibody and polyethylene glycol are used in the RIA. An immunologically identical, somewhat larger antigen is present in human serum; its concentration increases in multiple myeloma and in rheumatoid arthritis. The ICTP antigen seems to be cleared from the circulation by the kidneys, because glomerular filtration rates that are two-thirds of normal or less are associated with increased circulating ICTP concentrations. The CVs of the method are between 3% and 8% for a wide range of concentrations. The analysis of 40 serum samples can be completed in 4 h.
Lipid peroxidation and trace element status in diabetic ketotic patients: influence of insulin therapy
Authors: Faure P , Corticelli P , Richard M J , Arnaud J , Coudray C , Halimi S , Favier A , Roussel A M 
Published: January 2020

Abstract
Lipid peroxidation is known to accelerate aging and microvascular lesions in diabetic patients. We studied the acute influence of improved glycemic control on the concentrations of plasma lipid peroxidation intermediates [malondialdehydes (MDA), organic hydroperoxides (OHP)] in ketotic insulin-dependent diabetic patients, as well as the interplay of enzymes such as glutathione peroxidase (GPX) and CuZn superoxide dismutase (CuZn-SOD), and trace elements (Zn, Se, Cu) postulated to be involved in free radical protection. These plasma components were measured on the first day of hospitalization (T0) and when the patient had attained a stable glycemic state after continuous insulin treatment (T1). Plasma MDA and OHP concentrations were high at the beginning of the study but approached reference values after glycemic equilibration. Plasma zinc concentrations were significantly (P &lt; 0.05) decreased during the ketotic state, but also approached reference values with glycemic equilibration. Plasma selenium concentrations and GPX activity were relatively unchanged between T0 and T1. Erythrocyte GPX activity measured at T1 in six patients was below the reference values, whereas CuZn-SOD activity was not affected. Our results show that enhanced lipid peroxidation is associated with decreased zinc plasma concentrations in ketotic patients and underline the beneficial effects of continuous insulin infusion. The mechanisms involved are still unclear but may indicate the importance of extracellular zinc transfer secondary to glycemic disorders.
Fast HPLC determination of serum free fatty acids in the picomole range
Authors: Püttmann M , Krug H , von Ochsenstein E , Kattermann R 
Published: January 2020

Abstract
We developed a method for determining individual free fatty acids in serum by using a modified one-step Dole extraction, derivatization, and a new high-performance liquid chromatographic (HPLC) separation. Sample handling is minimized to a single transfer of the fatty acids (upper layer of the Dole extract), which are readily derivatized at 85 degrees C with p-bromophenacyl bromide without significant hydrolysis of esterified fatty acids. The derivatization mixture is directly injected into the HPLC apparatus. The new method, which uses C6 (3-microns particle) column material and an isocratic acetonitrile-water eluent, separates nearly to baseline 12 of the physiologically most abundant long-chain fatty acids (C12-C22) in &lt; 20 min with a detection limit of approximately 2 pmol. It is therefore suitable for routine analysis even with basic HPLC equipment and can easily analyze a series of 10-20 samples in about 2 h including extraction until first results are available. The method is also applicable to other matrices than serum, e.g., for determination of precursor fatty acids such as arachidonic acid in platelets or of fatty acid patterns liberated by lipases or phospholipases A1/A2 in test systems.
Increased fetal hemoglobin in insulin-treated diabetes mellitus contributes to the imprecision of glycohemoglobin measurements
Authors: Kilpatrick E S , Small M , Rumley A , Dominiczak M H 
Published: January 2020

Abstract
An increased prevalence of fetal hemoglobin (HbF) has been described in pediatric insulin-dependent patients. The popular electroendosmotic method for glycohemoglobin includes HbF. In an adult population comprising 50 insulin-treated and 57 non-insulin-treated diabetic patients and 57 control subjects, we measured HbF by HPLC and measured glycohemoglobin by both HPLC and an electroendosmotic method. Of the insulin-treated patients, 46% had concentrations of HbF &gt; or = 0.5%, compared with 25% of non-insulin-treated patients and 23% of controls (P &lt; 0.02). In the insulin-treated patients, the two glycohemoglobin methods correlated best when the HPLC measurements included HbF (r = 0.92 vs r = 0.84). Fructosamine concentrations correlated best with glycohemoglobin concentrations determined by methods that accounted for HbF. The true between-batch CV of the electroendosmotic assay increased (from 4.33% to 8.33%) when variable interpatient HbF concentrations were included. Thus, HbF must be considered when interpreting glycohemoglobin measured by an electroendosmotic method and when comparing it with other measures of glycemic control.
International cooperation in analytical chemistry: experience of antidoping control at the XI Pan American Games
Authors: Segura J , Pascual J A , Ventura R , Ustaran J I , Cuevas A , Gonzalez R 
Published: January 2020

Abstract
We describe the experience of the international cooperation carried out for antidoping control at the XI Pan American Games. A temporary accreditation was granted by the International Olympic Committee to the accredited laboratory of Barcelona (Spain) to set up a Doping Control Laboratory in Havana. Two other laboratories from Mexico and Cuba contributed personnel, materials, and instrumentation. The main issues associated with the preparation and organization of the project are described. During 16 days, 741 urine samples were tested for stimulants, narcotics, anabolic steroids, beta-blockers, diuretics, cannabinoids, local anesthetics, and human chorionic gonadotropin by gas-liquid chromatography, gas chromatography/mass spectrometry, high-performance liquid chromatography, and immunoassay techniques. Analytical methodologies, quality-control strategies, and the main results are reported.
Interference of lysophosphatidylcholine in hormone radioimmunoassays
Authors: Lepage N , Roberts K D , Langlais J 
Published: January 2020

Abstract
The interference of synthetic and naturally occurring detergents in immunoassays is well documented. In the present study, we evaluated the effect of lysophosphatidylcholine (LPC) and found that the lysophospholipid interfered with formation of the antigen-antibody complex in hormone immunoassays. In the presence of LPC (100 mumol/L), progesterone was overestimated by 29%. Furthermore, physiological concentrations of LPC (140 mumol/L) interfered with the assays of cortisol, progesterone, and aldosterone, resulting in overestimations of 35%, 30%, and 27%, respectively. The addition of albumin decreased the interference by LPC to 7% in the assay of cortisol and progesterone when the LPC:albumin ratio was unity. Adding cholesterol (100 mumol/L) also reduced by 50% the interference induced by LPC. Finally, treating plasma to increase the endogenous LPC concentration also resulted in interference in the cortisol assay. Thus, interpretation of the results of these assays should take into consideration the endogenous serum albumin:LPC ratio.