bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of polyethylene glycol 400 in urine by direct-injection high-performance liquid chromatography
Authors: Young G O , Ruttenberg D , Wright J P 
Published: January 2020

Abstract
We describe a new "high-performance" liquid chromatographic (HPLC) method for estimating polyethylene glycol 400 (PEG 400) in urine. Direct injection of diluted urine samples onto the column eliminates the necessity for lengthy preparative steps, resulting in considerable saving of both time and chemicals. High analytical recoveries (94-102%) and a rapid rate of analysis are achieved. Results vary linearly with concentrations from 0.2 to 1.6 g/L and the six major components can be individually quantified precisely at all concentrations in this range. This method shows better sample recovery, sensitivity, and reproducibility than does a previously described method. The increased sensitivity should allow the use of lower oral doses of polyethylene glycol 400 in future studies of intestinal permeability.
Evaluation of the clinical usefulness of a chemiluminometric method for measuring creatine kinase MB
Authors: Pearson J R , Carrea F 
Published: January 2020

Abstract
The use of creatine kinase isoenzymes (CK-MB) in the diagnosis of acute myocardial infarction (AMI) is well established. We evaluated the use of a new chemiluminometric method (CK-Ciba) for measuring CK-MB by calculating its sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency for diagnosing AMI. We tested 633 samples from 229 patients within 4 h of receipt. The patients were divided into four groups: (1) patients who had an AMI, (2) patients who had AMI ruled out, (3) patients who had CK-MB measured for reasons other than to rule out AMI, and (4) patients who had only one sample drawn. Only patients in Groups 1 and 2 were used in the study. AMI was diagnosed by a cardiologist. The prevalence of AMI in our population was 0.18. A receiver-operator characteristic curve was used to establish optimal values for identifying AMI with the CK-Ciba results: CK-MB greater than or equal to 10 micrograms/L and a CK-MB index of greater than or equal to 3.0 (micrograms of CK-MB per U of CK x 100). Using these values, we calculated a sensitivity of 1.00, specificity of 0.97, positive predictive value of 0.87, negative predictive value of 1.00, and a diagnostic efficiency of 0.97. We conclude that the CK-Ciba method has high sensitivity, high specificity, and good predictive values for CK-MB and is appropriate to use to rule out AMI.
Iron and total iron-binding capacity in serum of patients receiving iron-dextran: Kodak Ektachem methodologies, spectrophotometry, and atomic-absorption spectrometry compared
Authors: Vercammen M , Goedhuys W , Boeyckens A , De Roy R , Sennesael J , Sevens C , Gorus F 
Published: January 2020

Abstract
We compared the analytical performance of the Kodak Ektachem XR700 assays of iron (Fe) and total iron-binding capacity (TIBC) with that of a conventional ferrozine assay (performed with a Cobas-Bio) and occasionally with that of atomic-absorption spectrometry (AAS). The correlation was modest between Kodak and Cobas-Bio concentrations of Fe in serum (r = 0.79). Multiple outliers were noticed in samples from hemodialysis patients, with Cobas values exceeding those of Kodak by as much as 26 mumol/L. These intermethod differences were not dissipated by dialysis, but were invariably accompanied by an even higher total Fe content of the serum as judged by AAS (20 to 80 mumol/L higher). TIBC values by Kodak and Cobas-Bio were highly correlated (r = 0.99); again, the Cobas-Bio results exceeded those by Kodak in some hemodialysis patients, but always for samples with higher Fe concentrations by the Cobas-Bio. By AAS, the TIBC values of these patients also exceeded those by Kodak, to about the same extent as observed for serum Fe. These intermethod differences in Fe and TIBC were seen only in patients who had received an intravenous Fe-dextran (Imferon) injection two to three days before blood sampling but could be generated in vitro by adding Imferon to serum from normal controls. Less than 6% of dextran-bound Fe is measured as Fe by Kodak, as opposed to 20-30% by Cobas-Bio and 89-120% by AAS. We conclude that the Kodak Fe slides are superior to liquid reagents, by exclusively measuring protein-bound circulating Fe pools.
Clinical evaluation of an automated chemical inhibition assay for lactate dehydrogenase isoenzyme 1
Authors: Onigbinde T A , Wu A H , Johnson M , Wu Y S , Collinsworth W L , Simmons M J 
Published: January 2020

Abstract
We evaluated an automated assay for lactate dehydrogenase (LD; EC 1.1.1.27) isoenzymes, supplied by Boehringer Mannheim Diagnostics (BMD) and based on selective chemical inhibition of non-LD-1 isoenzymes by guanidine thiocyanate. Results were compared with the Roche Isomune LD-1 method. The Hitachi 717 analyzer was used to measure enzyme activity for both procedures in 229 serum samples. One hundred specimens were also analyzed by the Helena rapid electrophoresis (REP) method. We determined the limit of linearity of the BMD method to be about 1200 U of LD-1 per liter. The analytical correlation of BMD (y) with Isomune (x) yielded y = 1.0x + 0.5 U/L, r = 0.997, Sy/x = 16.9 (range 20-1397 U/L). The regression equation for BMD vs REP was y = 1.1x + 7.2% (r = 0.800, Sy/x = 7.4, range 14-83%). Average values for within-run precision for low (38 U/L), medium (180 U/L), and high (865 U/L) controls were 4.1%, 1.0%, and 0.5%, respectively (16 trials of six each). The average values for run-to-run precision were 4.1%, 1.7%, and 1.1%, respectively, for these controls (n = 16). We used receiver-operating characteristic curves to determine optimum decision limits. Using an LD-1 cutoff of 40% of total LD, we obtained a clinical sensitivity of 97-100% and a specificity of 95% when blood was collected during the optimum interval, 24-48 h after the onset of chest pain. We conclude that the BMD LD-1 assay is equivalent to the immunochemical and electrophoretic assays for measuring the LD-1 isoenzyme.
A kinetic assay for urea in undiluted urine specimens
Authors: Scott P , Maguire G A 
Published: January 2020

Abstract
We describe a kinetic assay for quantifying urea in undiluted urine samples. The assay linearity extends to urea concentrations of 400 mmol/L, is free from interference from blood (10 mL/L) or bilirubin (1 mmol/L), is sufficiently precise for routine use, and correlates well with an established method for assay of diluted urine samples.
Isolation and structural identification of 9hydroxy-9desmethyl-cyclosporine
Authors: Bowers L D , Norman D D , Yan X X , Scheeler D , Carlson K L 
Published: January 2020

Abstract
A metabolite of cyclosporine has been isolated and its structure identified through use of HPLC and tandem mass spectroscopy. Fast atom bombardment mass spectrometry of an HPLC fraction co-eluting with 1 eta hydroxy-cyclosporine (M17) indicated that the mass of this metabolite was 2 Da greater than that of cyclosporine. Further isolation by HPLC yielded a pure fraction, which we analyzed with tandem mass spectrometry. Linear acyl fragment ions originating from the metabolite under collision-induced dissociation were consistent with the difference in mass being associated with amino acid 9 in the cyclosporine backbone. We propose a nomenclature system for future discussion of cyclosporine metabolites.
Ultraviolet fluorescence of human sera: I. Sources of characteristic differences in the ultraviolet fluorescence spectra of sera from normal and cancer-bearing humans
Authors: Hubmann M R , Leiner M J , Schaur R J 
Published: January 2020

Abstract
The ultraviolet fluorescence emission spectra of sera from apparently healthy persons and of sera from cancer patients frequently show significantly different curve shapes. A biparametric fluorescence method has been developed to use these deviations to detect patients with malignant diseases (Clin Chem 1986;32:1974-8). However, the pathobiochemical reasons for these differences of diagnostic importance have thus far been unclear. To find a relevant explanation for the described effect, we focused our interest on human serum proteins, the materials mainly responsible for the intrinsic fluorescence of sera in this spectral region. Human sera of various protein compositions were selected according to their protein pattern, determined by cellulose acetate electrophoresis, and their intrinsic fluorescence properties were investigated. We found that the emission spectra of human sera were correlated with their relative protein compositions, albumin and alpha-2 globulins being the most significantly correlated with the fluorescence intensity ratios. Because increased percentages of alpha-2 globulins and decreased percentages of albumin frequently accompany malignancies, we suggest that this condition accounts for the differences between the emission spectra of sera from normal and cancer-bearing humans.
"VRA-GlcNAc": novel substrate for N-acetyl-beta-D-glucosaminidase applied to assay of this enzyme in urine
Authors: Pócsi I , Taylor S A , Richardson A C , Aamlid K H , Smith B V , Price R G 
Published: January 2020

Abstract
We describe a new chromogenic substrate and assay for determining N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) activity in normal and pathological human urine. The novel substrate, ammonium 5-[4-(2-acetamido-2-deoxy-beta-D-glucopyranosyloxy)-3- methoxyphenylmethylene]-2-thioxothiazolidin-4-one-3-ethan oate (VRA-GlcNAc), is prepared by condensation of vanillyl N-acetyl-beta-D-glucosaminide and rhodanine-3-ethanoic acid. The phenol released by enzyme action has an intense absorption peak at 492 nm (epsilon = 37,000 L.mol-1.cm-1). The Km for NAG in urine was 0.5 mmol/L at pH 4.5. The substrate solution may be stored at 4-7 degrees C for one week without any increase in the substrate blank. For optimal assay conditions, we used a substrate concentration of 3 mmol/L and a 15-fold sample dilution at pH 4.5-5.0, with measurement at 505 nm, not significantly different from that at 492 nm. The sensitivity of the assay with VRA-GlcNAc as substrate is twice that of the MNP-GlcNAc [2-methoxy-4-(2'-nitrovinyl)-phenyl GlcNAc] procedure (Clin Chim Acta 1982;124:195-204) and can detect low amounts of minor NAG isoenzymes. This assay is an improvement on previously available colorimetric methods and could be easily incorporated into kits based on either an enzyme calibrant or the molar absorptivity of the phenol.
Evaluation of dialysis treatment in uremic patients by gel filtration of serum
Authors: Osada J , Gea T , Sanz C , Millan I , Botella J 
Published: January 2020

Abstract
A group of substances of molecular masses between 300 and 1500 Da have been found to be toxic metabolites in patients with uremia. We determined the concentration in serum of these molecules in the following groups of patients: two hemodialyzed groups (one with cuprophane and the other with polyacrylonitrile dialyzers), one group treated with continuous ambulatory peritoneal dialysis, one group of nondialyzed azotemic patients, and one control group of healthy persons. Ultrafiltrates of the subjects' sera were fractionated on Sephadex G-15 followed by ion-exchange chromatography. Eluates were monitored by absorbance at 254 and 206 nm. Partially characterized peaks P1 and P2, obtained by gel filtration, correlated with the concentration of creatinine in serum; their concentrations were significantly (P less than 0.01) larger in hemodialyzed groups than in peritoneal dialyzed or in nondialyzed azotemic patients. After ion-exchange chromatography, two peaks (P'5 and P'6) correlated with serum creatinine and also were larger in hemodialyzed patients than in the other groups. Apparently, adequate discrimination is obtained by gel-filtration analysis and further analysis by ion-exchange chromatography does not provide additional information in most of the affected patients.
Heterogeneous enzyme immunoassay of alpha-fetoprotein in maternal serum by flow-injection amperometric detection of 4-aminophenol
Authors: Xu Y , Halsall B , Heineman W R 
Published: January 2020

Abstract
A sandwich-type heterogeneous enzyme immunoassay with flow-injection analysis for alpha-fetoprotein (AFP) in human serum has been developed. 4-Aminophenol, the product of enzymatic reaction, is detected amperometrically. The interassay CV for this electrochemical enzyme immunoassay was less than 8.2%, with a minimum detection limit for AFP of 0.163 micrograms/L. The calibration curve had a linear range of 0.316-100 micrograms/L. Studies with 48 human maternal serum samples, comparing results by this method with those by a commercial kit, showed a good correlation (r = 0.961). This procedure provides an alternative method for determining low concentrations of AFP in human maternal serum.
Idiometric assay: noncompetitive immunoassay for small molecules typified by the measurement of estradiol in serum
Authors: Barnard G , Kohen F 
Published: January 2020

Abstract
We report here a novel noncompetitive immunoassay applicable to the measurement of small-molecular-mass compounds and typified by the direct measurement of estradiol in serum. Two types of anti-idiotypic antibody recognize different epitopes within the hypervariable region of the specific primary antibody (e.g., anti-estradiol). The first anti-idiotype (betatype) recognizes an epitope at the unoccupied binding site, which is masked in the presence of the analyte (e.g., estradiol). The second (alphatype) recognizes an epitope close to the binding site and is unaffected by the presence or absence of the analyte, but is sterically hindered from binding to the primary antibody in the presence of the betatype. The use of these matched antibodies (primary antibody, alphatype, and betatype) has enabled the development of a method for determining antibody occupancy that is not based on a conventional two-site assay. An excess amount of purified monoclonal antibody against estradiol is immobilized onto the walls of microtiter wells. After the capture of analyte, the unoccupied antibody sites are blocked by the addition of an excess amount of betatype. Subsequently, analyte occupancy is determined by the addition of excess europium-labeled alphatype, incubation, washing, and time-resolved fluorometry. The method demonstrates good sensitivity, precision, and comparability with alternative competitive immunoassays.
Double monoclonal time-resolved immunofluorometric assay of beta 2-microglobulin in serum
Authors: Tienhaara A , Eskola J U , Näntö V 
Published: January 2020

Abstract
Previously reported immunochemical assays of beta 2-microglobulin (beta 2m) have usually been based on polyclonal antisera. We have developed a "sandwich"-type time-resolved immunofluorometric assay (TR-IFMA) for beta 2m in serum, based on two monoclonal antibodies against human beta 2m. Microtiter wells are coated with the capture antibody, and the tracer antibody is labeled with a europium chelate. In a simple and fast assay procedure, prediluted serum samples are incubated with the tracer for 1 h in the microtiter wells, after which the wells are washed and the fluorescence of Eu is measured. The mean analytical recovery was 101.8% and results by TR-IFMA showed a good linear correlation with those by an established radioimmunoassay. The analytical range of TR-IFMA is large and well suited for clinical purposes.
Simultaneous measurement of two major prostacyclin metabolites in urine
Authors: Zureick S , Nadler J , Yamamoto J , Horton R 
Published: January 2020

Abstract
We describe a combined HPLC-RIA technique to measure both major metabolites of prostacyclin (PGI2): 6-keto PGF1 alpha and 2,3-dinor-6 keto PGF1 alpha. The measurement of the former, which originates from renal blood vessels, and the latter, from systemic vessels and the liver, may provide a better overall evaluation of production than measurement of one metabolite. An aliquot of acidified urine with added 3H-labeled metabolites is adsorbed and then eluted from a C18 Bond-Elut column. The sample is then passed through an HPLC system by use of an isocratic solvent combination that separates the two metabolites from known prostaglandins. The purified metabolites are then quantified by RIA. Using a logit-log10 transform, one can measure between 12 and 250 pg of either metabolite, with high accuracy and precision (CVs of 12% for a low concentration and 7% for a high concentration). Reference values for apparently healthy subjects were, respectively, 107 (SD 45) and 171 (SD 69) ng/g creatinine for 6-keto PGF1 alpha and the dinor metabolite in men (n = 18) and 45 (SD 22) and 141 (SD 28) ng/g creatinine, respectively, in women (n = 15). Indomethacin in standard doses reduced both metabolite values by 50%. Intravenous administration of angiotensin II (5 ng/kg of body wt per minute) did not alter excretion rates, but equipressor doses of norepinephrine (0.1 microgram/kg per minute) increased the production of both metabolites (6-keto greater than dinor).
Determination of beta-carotene and its cis isomers in serum
Authors: Rushin W G , Catignani G L , Schwartz S J 
Published: January 2020

Abstract
All-trans-beta-carotene was resolved from its cis isomers in human serum by reversed-phase "high-performance" liquid chromatography. Absorption spectra of the cis peak suggested that 13-cis-beta-carotene was the predominant cis isomer. Analyses and recovery studies of fresh and stored sera eliminated the possibility that isomerization had occurred in samples during handling or storage. The average analytical recovery was 101.9% for standards of the all-trans-, 9-cis-, and 13-cis-beta-carotene compounds in pooled serum samples. We also demonstrated that cis isomers had not formed after the blood was drawn and that cis isomers of beta-carotene are present at significant concentrations in the human circulation.
Excess serum osmolality gap after ingestion of methanol
Authors: Meatherall R , Krahn J 
Published: January 2020

Abstract
Two cases of methanol ingestion and one case of combined methanol and ethylene glycol ingestion are presented to illustrate the large differences that exist between the serum osmolality gap and the measured methanol (plus ethylene glycol) concentration(s) before treatment of these poisonings. After treatment with intravenous ethanol and hemodialysis was initiated, the differences disappeared in all three cases. We speculate that one or more metabolites with osmotic activity are formed in cases of methanol intoxication where no ethanol has also been consumed. The possible identity of these compounds is discussed.
Clinical laboratory regulation under the Clinical Laboratory Improvement Amendments of 1988: can it be done?
Authors: Peddecord K M , Hammond H C 
Published: January 2020

Abstract
This report examines logical but not yet widely recognized ramifications of the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88), federal legislation that will require certification of all laboratories examining human specimens. Examination of the CLIA'88 committee reports and committee hearings suggest that more than the conventional approach to laboratory standards will be needed to meet the public's expectations as articulated by our elected representatives. The conventional approach to clinical testing standards seeks to assure quality by regulating the laboratory analytical process. However, little empirical evidence is available to support or refute this model, which has been used during the past 25 years. One alternative paradigm for laboratory standards is an approach that examines the total laboratory testing process, including the selection, ordering, and interpretation of the test as well as the laboratory analysis per se. The history of controversy over laboratory standards--especially personnel standards, the glacial federal regulatory rulemaking process, public expectations of fail-safe technology, among other factors--suggests the implementation of CLIA'88 will be a lengthy and vigorously debated contest. The risk of a test is seldom inherent in the test itself, but rather is a function of the context in which the test is being used to provide information for medical decision making. Our premise is that diagnostic tests must be examined in the context of the laboratory testing situation. We suggest that now is the appropriate time for laboratory professionals, practicing physicians, and the public to abandon conventional thinking regarding clinical laboratory standards. We believe that CLIA'88 reflects a shift in public expectations toward fail-safe laboratory testing and the need for additional government oversight in laboratory test quality. If these new expectations persist, CLIA'88 represents a potential landmark in the course of federal authority and the practice of medicine in the United States.
Direct chemiluminescence immunoassay of estradiol in saliva
Authors: De Boever J , Kohen F , Bouve J , Leyseele D , VandeKerckhove D 
Published: January 2020

Abstract
A sensitive and simple direct solid-phase chemiluminescence immunoassay is described for estradiol in saliva. In this assay, a second antibody is bound to the wells of microtiter plates. Either buffer with standards or saliva (100 microL) is incubated in these wells with monoclonal anti-estradiol antibody and with estradiol-isoluminol conjugate. Incubation time is 2 h. Chemiluminescence of the bound fraction is measured in a manually operated luminometer (Biocounter). The assay has a detection limit of 3.8 pmol/L; analytical recovery of added estradiol is 96.8% (SD 7.0%); within- and between-assay CVs range between 2.5% and 12.7%. Forty unknown saliva samples can be assayed and results calculated within 4.5 h. Results of a slightly modified procedure-with black microtiter plates and a prototype of an automated plate reader (Luminoskan)--compare well with those of the described method (r = 0.97). Because steroid-binding globulins have been found in saliva, the effect of displacing agents on the results of the direct chemiluminescence assay is described.
Concentrations of apoprotein CII, CIII, and E in total serum and in the apoprotein B-containing lipoproteins, determined by a new enzyme-linked immunosorbent assay
Authors: Alsayed N , Rebourcet R , Chapman J 
Published: January 2020

Abstract
We describe a new enzyme-linked immunosorbent assay (ELISA) that permits direct determination of apoprotein (apo) CII, CIII, and E in total serum as well as in apo B-containing lipoprotein particles. To validate this ELISA technique, we studied several aspects of the assay: its specificity, the influence of the conditions of conservation of plasma and of lipoprotein fractions, the effect of delipidation, and its reproducibility. We measured the concentrations of apo CII, CIII, and E in total serum and in apo B-containing lipoproteins from a pool of normal sera and in sera from 75 healthy subjects. After sequential ultracentrifugation, the content of apo CII, CIII, and E in the major lipoprotein fractions was also determined. Total serum or plasma could be stored at -20 or -50 degrees C for at least six weeks and the isolated lipoprotein fractions for as long as four weeks, which suggests a protective effect of total serum on lipoprotein particle structure. Advantages of this ELISA include (a) its specificity, sensitivity, and reliability; (b) better discrimination than determination of total serum apoprotein; (c) easier application and greater rapidity; and (d) the possibility of application to population screening.