bluuebunny/crossref_metadata_2025_split huggingface dataset:
Precipitation with polyethylene glycol and density-gradient ultracentrifugation compared for determining high-density lipoprotein subclasses HDL2 and HDL3
Authors: Widhalm Kurt , Pakosta Renate 
Published: January 2020

Abstract
The purpose of this study was to compare quantification of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 by precipitation with polyethylene glycol (PEG) with that by density-gradient ultracentrifugation. Fresh serum samples from 32 fasting, obese children were analyzed with precipitation reagent "Quantolip" (Immuno AG), and then fractionated with a Beckman TL 100 ultracentrifuge with a swinging-bucket rotor. After centrifugation we carefully removed the supernate with a syringe and measured the cholesterol from each fraction enzymatically with CHOD-PAP reagent (Boehringer Mannheim). The low-density lipoprotein (LDL-), HDL2-, and HDL3-cholesterol values measured by ultracentrifugation did not differ significantly from those obtained by precipitation; the correlation coefficients (r) between the two methods were 0.96 for LDL, 0.75 for HDL2, and 0.96 for HDL3. The relatively simple PEG precipitation method used in this study measures total HDL and its major subclasses HDL2 and HDL3 with accuracy and precision comparable with those of the well-established ultracentrifugation method.
Electrochemical enzyme immunoassay for phenytoin by flow-injection analysis incorporating a redox coupling agent
Authors: Tang Hua T , Halsall H BrIan , Heineman William R 
Published: January 2020

Abstract
Using phenytoin as a model analyte, we demonstrate an electrochemical enzyme immunoassay based on flow-injection analysis and incorporating 2,6-dichloroindophenol (DCIP) as a redox coupling agent. DCIP reacts with NADH to form NAD+ and DCIPH2, the reduced form of the coupling agent. The production of DCIPH2 is monitored at +250 mV vs Ag/AgCl. This low applied potential improves selectivity in the biological matrix, differentiating against components that are oxidizable at the more-positive potentials required for direct electrochemical detection of NADH. The kinetics-based assay also eliminates other common interferences, mainly from ascorbic acid and glutathione. This system does not require precolumns or analytical columns for isolation of the NADH response. Good agreement with a routine clinical laboratory procedure for phenytoin is obtained for clinical samples (r = 0.95), illustrating the feasibility of such an approach.
Individual differences in lutropin immunoreactivity revealed by monoclonal antibodies
Authors: Pettersson Kim S , Söderholm JuanIta R 
Published: January 2020

Abstract
We screened 11 monoclonal anti-lutropin (LH) antibodies for use in two-site immunometric combinations, with time-resolved fluorescence as the detection principle. Seven immunofluorometric assays (IFMA), six detecting only the intact hormone and one detecting both the intact hormone and free beta subunit, were compared with each other and with a conventional radioimmunoassay involving a polyclonal antiserum. Two monoclonal antibodies that exclusively reacted with intact LH showed restricted reactivity with LH in 25% of the samples tested. The LH of one individual was not detected at all by one of the antibodies. The existence of two distinct populations suggests the existence of a genetic variant of LH. A comparison of the results obtained by IFMAS with those by radioimmunoassay showed marked discrepancies in the low range, with IFMAS measuring much lower values. The excellent correlation between the various monoclonal IFMA strongly suggests that the discrepancies seen are caused by the insufficient sensitivity and matrix effects of the radioimmunoassay.
Quantifying bone and liver alkaline phosphatase by the resolution of two-component inactivation data obtained with a centrifugal analyzer
Authors: Forsman Rodney W , O'Brien John F 
Published: January 2020

Abstract
In this method we use a linear equation to resolve two-component decay data from the urea inactivation of mixtures of alkaline phosphatase (EC 3.1.3.1) of liver and bone origin. The specificity for the bone/liver isoenzyme is enhanced by including L-phenylalanine in the urea reaction to inhibit the intestinal and placental forms. Bone and liver fractions are each quantified from results of a single run on the centrifugal analyzer. Total activity and the L-phenylalanine-inhibited fraction are measured on separate runs. A simplification of this method has been used in our laboratory for 14 years in performing greater than 80,000 analyses of clinical specimens. Speed, accuracy, and precision are improved over previous methods by this mathematical solution. Data reduction is automated through the use of a personal computer interfaced to the analyzer. With such systems generally available, this method can now be suggested as suitable for routine use to separate these and perhaps other isoenzyme mixtures.
Individual probability for onset of full-blown disease in patients infected with human immunodeficiency virus type 1
Authors: Reibnegger Gilbert , Spira Thomas J , Fuchs Dietmar , Werner-Felmayer GabrIele , Dierich Manfied P , Wachter Helmut 
Published: January 2020

Abstract
Increased concentrations of neopterin, a marker for cell-mediated immune activation, and decreased numbers of CD4+ T cells, are predictors for progression of disease after infection with human immunodeficiency virus type 1. Previous studies have demonstrated different rates of onset of full-blown acquired immunodeficiency syndrome (AIDS) for groups of patients, defined by laboratory marker values, who were initially symptom-free. By re-analysis of one such study, we demonstrate how for an individual patient, the individual marker values, together with a prior risk estimate, can be converted into current or accumulated post-test probability of onset of AIDS at a certain time. We used a statistical technique suggested by Albert et al. (Clin Chem 1984;30:69-76), which allows incorporation of fixed and time-dependent covariates. Besides allowing individual projections, the method shows that the predictive abilities of CD4+ T cell numbers and of neopterin concentrations do not vary greatly with regard to time of observation; both laboratory markers independently modulate the underlying prior probability of AIDS onset, which is significantly increased with the passage of time.
Diagnostic and prognostic utility of phospholipase A activity in patients with acute pancreatitis: comparison with amylase and lipase
Authors: Kazmierczak Steven C , Van Lente Frederick , Hodges Edna D 
Published: January 2020

Abstract
We compared the diagnostic and prognostic utility of phospholipase A (PLA; EC 3.1.1.4) for acute pancreatitis with that of amylase and lipase by analysis of sera from 151 consecutive patients presenting with abdominal pain in whom assays of serum amylase and (or) lipase had been ordered. We determined the diagnostic accuracy for both the initial and the peak enzyme activities. Maximal diagnostic accuracy obtained for the initial activities of amylase, lipase, and PLA was 0.83, 0.83, and 0.76 at cutoff values of 650, 650, and 41 U/L, respectively. Use of peak enzyme activities showed maximal diagnostic accuracy of 0.85, 0.86, and 0.73 at cutoff values of 650, 1050, and 42 U/L, respectively. Receiver-operator characteristic curve analysis revealed the diagnostic performance of amylase and lipase to be similar, whereas that of PLA was almost random and not incremental. As with amylase and lipase, PLA activities in sera showed no relation to patients' survival; three patients who died after an attack of acute pancreatitis failed to demonstrate the dramatic increases in PLA activity previously described. We conclude that assessing the severity of acute pancreatitis by using enzyme activities still remains problematical. Measurements of amylase or lipase activities provide similar diagnostic discrimination when appropriate cutoff values are used and remain the methods of choice for diagnosis of acute pancreatitis.
Use of chicken antibodies in enzyme immunoassays to avoid interference by rheumatoid factors
Authors: Larsson Anders , Karlsson-Parra Alex , Sjöquist J 
Published: January 2020

Abstract
Rheumatoid factor (RF) is a major source of interference in many immunoassays. Most immunoassays use mammalian polyclonal or monoclonal antibodies, and RF can react with IgG from mammalian species, thus causing false-positive results. In this work we have studied RF interference in a sandwich ELISA, where RF in the sample may react with both the capture antibody and the detection antibody to give a false-positive reaction. We show that rheumatoid factors do not react with chicken IgY; if the capture antibody or detection antibody (or both) is of avian origin, the interference of RF or other anti-IgG antibodies in sandwich ELISA can be avoided.
DNA enzyme immunoassay: general method for detecting products of polymerase chain reaction
Authors: Mantero Giovanni , Zonaro Antoneil , Albertini Aiberto , Paola Alberto , Primi Daniele 
Published: January 2020

Abstract
We developed a new colorimetric method, DNA enzyme immunoassay (DEIA), for detecting specific hybrids of complementary nucleic acids and applied it to the detection of hepatitis B virus (HBV) DNA amplified from serum samples by means of the polymerase chain reaction (PCR) technique. The method is based on the ability of an anti-DNA monoclonal antibody to discriminate between single-stranded and double-stranded DNA. A solid phase was coated with a specific oligonucleotide probe, internal to the amplified region of HBV DNA, via an avidin-biotin bridge. The denatured PCR product was hybridized with the solid-phase probe, and the amplified DNA probe hybrid was then incubated with a monoclonal antibody specific for double- but not single-stranded DNA. Colorimetric detection of the DNA-antibody complex was achieved by adding an anti-mouse Ig antibody labeled with horseradish peroxidase. The combined use of DEIA and PCR can reveal a few HBV genome copies present in a serum sample. This method has several advantages: (a) the sensitivity is adequate for the detection of amplified DNA; (b) the signal is associated with the hybridization event, independently of modifications of the probe or of the amplification primers; and (c) the test is simple and rapid and, most importantly, requires only the standard facilities of a routine clinical laboratory.
Macromolecular creatine kinase type 1: a serum marker associated with disease
Authors: Laureys Muriȵl , Sion Jean-Pau , Slabbynck Hans , Steenssens Laurette , Cobbaert Chrlsta , Derde Marie-Paul , Gorus Frans K 
Published: January 2020

Abstract
The prevalence of circulating macromolecular creatine kinase type 1 (macro CK type 1 or CK-immunoglobulin complexes) is significantly higher in a patient population selected for CK isoenzyme assay than in age- and sex-matched blood donors (n = 1304). In greater than 8000 patients studied, 49 individuals with macro CK type 1 were identified, yielding an overall prevalence of 0.61%. Macro CK type 1 complexes occurred more frequently in women and in patients older than 70 years, and were often associated with complications of cardiovascular disease, life-threatening conditions, and poor outcome. These latter clinical associations could arise, at least partly, from the selection of patients for whom CK isoenzyme analysis was ordered.
Performance of techniques used to detect drugs of abuse in urine: study based on external quality assessment
Authors: Wilson J F , Williams J , Walker G , Toseland P A , Smith B L , Richens A , Burnett D 
Published: January 2020

Abstract
Twenty-five samples of lyophilized urine from the U.K. External Quality Assessment Scheme for Drugs of Abuse were analyzed by an average of 95 laboratories between April 1987 and December 1989. Samples contained mixtures of analytes and included replicated concentrations of morphine, methadone, amphetamine, and cocaine at 0, 1, 2, and 5 mg/L and of benzoylecgonine at 0, 0.4, 1, 2, and 4 mg/L. Some chromatographic techniques were inadequate for detecting morphine, amphetamine, cocaine, and benzoylecgonine at the lower concentrations of analytes studied: gas-liquid chromatography was least sensitive for morphine; in-house thin-layer chromatography (TLC) was least sensitive for the other analytes. Few significant differences in specificity were detected between techniques, although significant interference from structurally related compounds was demonstrated in assays of morphine, methadone, and amphetamine. Exceptions were the Boehringer (BCL) test for opiates and TLC applied to amphetamine and benzoylecgonine, which demonstrated considerable lack of specificity.
Genetic screening of newborns for sickle cell disease: correlation of DNA analysis with hemoglobin electrophoresis
Authors: Skogerboe KrIsten J , West Sheyla F , Murillo Magdalena D , Glass Michael W , Shaunak Santosh , Tait Jonathan F 
Published: January 2020

Abstract
Although DNA analysis based on the polymerase chain reaction (PCR) offers potential advantages for screening newborns for sickle cell disease, few data are available concerning the reliability of PCR-based tests for such screening. We describe a protocol for detecting the A, S, and C alleles of the beta-globin gene in dried blood from phenylketonuria screening cards. This method is based on PCR and detection with allele-specific oligonucleotide probes. Results of a blind comparison of PCR analysis of the dried blood with hemoglobin electrophoresis of whole-blood samples agreed for 80 of 81 samples. The single discrepancy is probably not attributable to a failure of the PCR method, but rather to limitations of the electrophoresis method. The PCR method should be a highly accurate means of detecting beta-globin alleles in routine genetic screening with dried blood already collected for (e.g.) phenylketonuria screening.
Development of a radioligand receptor assay for measuring follitropin in serum: application to premature ovarian failure
Authors: Schneyer Alan L , Sluss Patrick M , Whitcomb Randall W , Hall Janet E , Crowley William F , Freeman Ruth G 
Published: January 2020

Abstract
We have developed a radioligand receptor assay (RRA) with sufficient sensitivity and specificity for quantifying follitropin (FSH) in unextracted serum samples. Standard curves prepared by adding pituitary FSH to either buffer or gonadotropin-free serum were parallel and statistically indistinguishable in this assay, whereas gonadotropin-free serum alone had no activity. Cross-reactivity with related pituitary hormones was negligible. Pituitary FSH was calibrated with commonly used reference preparations so that RRA results could be compared with RIA results for identical standards. The patterns in daily blood samples in six normal menstrual cycles were similar by both methods. The mean RIA:RIA ratio in both the follicular and luteal phases was between 0.6 and 0.7, and at mid-cycle decreased to 0.48, suggesting an alteration of isohormone composition at mid-cycle. In 27 women with premature ovarian failure, RRA:RIA ratios ranged from below the RRA minimum detectable dose to 4.6, suggesting that immunoreactive FSH might not be capable of binding to the FSH receptor in some patients, whereas in patients with high RRA:RIA ratios, circulating inhibitors of FSH receptor binding might be present and perhaps contributing to the observed ovarian failure. Use of this RRA in conjunction with RIA and in vitro bioassays may better define the relative contribution of FSH isohormones, autocrine or paracrine modulators of FSH bioactivity, and FSH-receptor binding competitors to the "total FSH biological signal" as detected by the gonadal FSH receptor.
GCDFP-70 protein in cyst fluid identified as albumin and used to classify cysts in women with breast gross cystic disease
Authors: Balbín Milagros , Vizoso Francisco , Sánchez Luis M , Venta Rafael , Ruibal Alvaro , Fueyo Antonio , López-Otín Carlos 
Published: January 2020

Abstract
We used sodium dodecyl sulfate-polyacrylamide gel electrophoresis to study cyst fluids from women with breast gross cystic disease. The subjects could be classified into two categories according to the concentrations of protein GCDFP-70 in the cyst fluid: those with Type I cysts had a very low content of this protein; those with Type II cysts had very high concentrations. Analysis of the amino acid sequence of GCDFP-70 from both cyst fluid types confirmed that this protein is human plasma albumin. The average concentration of albumin found in Type I cyst fluids was 0.32 g/L and that corresponding to Type II was 10.16 g/L. Thus, albumin quantification from cyst fluids or analysis by either polyacrylamide or agarose gel electrophoresis provides a simple procedure for classifying these fluids, yielding results that correlate well with previous classifications based on other measurements such as sodium, potassium, and chloride concentrations. This albumin-based quantification method may improve the classification of breast cysts and might be useful in further studies on functional changes in the cysts and their relationship to breast cancer.
The spot test is not a reliable screening procedure for mucopolysaccharidoses
Authors: de Jong J G N , Hasselman J J F , van Landeghem A A J , Vader H L , Wevers R A 
Published: January 2020

Abstract
To check the reliability of the Ames MPS paper spot test, which is based on the Azure A dye, we sent a series of urine samples to three laboratories where the spot test is part of the metabolic screening for mucopolysaccharidoses. In these laboratories false-negative results ranged between 19% and 35% and false-positive results ranged between 12% and 29% of all samples submitted. In contrast, the quantitative dimethylmethylene blue test (Clin Chem 1989;35:1472-7) detected an increased glycosaminoglycan content in all urine samples from mucopolysaccharidosis patients and gave no false-positive results. In the latter procedure, glycosaminoglycan content is expressed per millimole of creatinine, and age-dependent reference values are used. We conclude that the Ames spot test and other spot tests are unreliable as a screening procedure for mucopolysaccharidoses and should not be used to screen for these diseases.
The biotin-(strept)avidin system: principles and applications in biotechnology
Authors: Diamandis E P , Christopoulos T K 
Published: January 2020

Abstract
The biotin-(strept)avidin system has been used for many years in a variety of different applications. Here we present a general overview of the system, describe its components and advantages, and show how the system is used in various applications, with emphasis on immunological and nucleic acid hybridization assays. This system is now considered a versatile independent technology with broad applications in many branches of biotechnology. Clearly, its use will continue to grow in the years to come.
Carcinoembryonic antigen in serum of patients with colorectal polyps: correlation with histology and smoking status
Authors: Shahangian S , Fritsche H A , Hughes J I 
Published: January 2020

Abstract
To measure the concentration of carcinoembryonic antigen (CEA) in serial serum specimens of 47 healthy subjects and in serial sera of 59 patients with colorectal polyps of confirmed histology, obtained before or after (sometimes both) polypectomy, we used the Roche EIA and the Hybritech Tandem-E double monoclonal immunoenzymometric assays. Both methods gave comparable results for the healthy subjects but discordant values for some polyp patients. The Tandem-E test gave increased CEA results more frequently for two groups of polyp patients, the group of ex-smokers with neoplastic polyps (n = 14) and the group of smokers (n = 20). Smokers had significantly greater (P less than 0.025) mean concentrations of serum CEA than did nonsmokers, irrespective of whether they were healthy or had colorectal polyps. Smokers with recurrent polyps demonstrated significantly greater (P less than 0.050) mean concentrations of serum CEA than did smokers with a first occurrence of polyps. Polypectomy was followed by statistically significant decreases (P less than 0.050) of mean concentrations of serum CEA, primarily in polyp patients who were smokers. However, although CEA increases occurred frequently in polyp patients who smoked, these abnormalities did not fully correlate with polyp histology.
Development and validation of an immunoradiometric assay of parathyrin-related protein in unextracted plasma
Authors: Ratcliffe W A , Norbury S , Heath D A , Ratcliffe J G 
Published: January 2020

Abstract
This two-site immunoradiometric assay for human parathyrin-related protein 1-86 (PTHRP1-86) in plasma uses a mouse monoclonal antibody to PTHRP1-34 coupled to cellulose particles for immunoextraction of N-terminal immunoreactivity, and a rabbit antiserum to PTHRP37-67 that is indirectly labeled with 125I-labeled PTHRP37-67 for quantifying the bound analyte. The detection limit of the assay is 0.23 pmol/L, corresponding to 0.4 pg (0.04 fmol) per tube, for a sample volume of 200 microL. Recovery of PTHRP1-86 added to serum is essentially quantitative, and within- and between-batch precision is 4.4% and 11.1%, respectively. PTH1-84, PTHRP18-34, PTHRP9-34, PTHRP1-34, and PTHRP37-67 do not cross-react in the assay at concentrations up to 2 nmol/L. Plasma concentrations of PTHRP1-86 were below or close to the detection limit of the assay in normal subjects and in patients with primary hyperparathyroidism, hypoparathyroidism, chronic renal failure, and normocalcemic malignancy. In 37 hypercalcemic patients with various malignancies, we found detectable PTHRP1-86 concentrations in 35 (95%, mean 7.4 pmol/L, range 0.46-24.7). The data support the proposed humoral role of PTHRP in cancer-associated hypercalcemia and suggest that the assay has clinical utility in the differential diagnosis of hypercalcemia.
Quantifying intermediary metabolites in whole blood after a simple deproteinization step with sulfosalicylic acid
Authors: Khan K , Blaak E , Elia M 
Published: January 2020

Abstract
We assessed the reproducibility, recovery, and stability of several circulating metabolites--glucose, pyruvate, lactate, alanine, glutamate, glutamine, 3-hydroxybutyrate, acetoacetate, and glycerol--in the presence of sulfosalicylic acid (SSA), which was used to deproteinize blood. The assays, which involved reactions linked to NADH/NAD+, were carried out at 37 degrees C and measured at 355 nm with a Cobas-Bio centrifugal analyzer. The intra- and interbatch CVs were less than 2.1%, except for the interbatch CV for 3-hydroxybutyrate at low concentration (15-30 mumol/L), which was 5.4%. Analytical recovery of metabolites added to blood ranged from 96.4% to 103.0%. Of the metabolites studied, all were stable at -20 degrees C for 90 days in the SSA-blood extract, except for glutamine and acetoacetate, which progressively decreased with time. We conclude that these nine circulating metabolites can be satisfactorily measured after a single deproteinizing step with SSA. This single-step procedure has several advantages over many of the currently used methods.