bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inexpensive double-antibody fluoroimmunoassay for aminoglycoside antibiotics, phenytoin, and theophylline in serum.
Authors: Kurtz M J , Billings M , Koh T , Olander G , Tyner T , Weaver B , Stone L 
Published: January 2020

Abstract
We describe simple, clinically useful double-antibody fluoroimmunoassays for amikacin, gentamicin, tobramycin, theophylline, and phenytoin. The fluorescent tracers were prepared by conjugation to fluorescein isothiocyanate; the antisera were raised in rabbits. A simple filter fluorometer and disposable culture tubes are used. The tracer, sample, and first and second antibodies are combined and incubated at room temperature for 30 min. A precipitation-acceleration buffer is added, the samples are centrifuged, and the fluorescence of the supernate is measured directly in the assay tube without decantation. Interferences, usually negligible, can be corrected for by use of a sample blank. Results compare favorably in performance with various commercially available RIA and enzyme immunoassays.
Beta-carotene determined in serum by liquid chromatography with an internal standard.
Authors: Driskell W J , Bashor M M , Neese J W 
Published: January 2020

Abstract
We describe a procedure for quantitative determination of beta-carotene in human serum. The 0.1-mL serum sample is precipitated with ethanol containing the internal standard, dimethyl-beta-carotene, then extracted with hexane. This extract is injected onto a reversed-phase, "high-performance" liquid-chromatography column, and the carotenes are resolved and eluted with an acetonitrile/methylene chloride isocratic solvent system. They are quantified from the peak-height ratios of their absorbance at 450 nm. About 14 min is required for each chromatogram. The procedure has excellent precision and is appropriate for routine use in analysis of large numbers of samples. The method should be particularly useful for clinical studies on the relationship of serum beta-carotene and cancer incidence in human populations.
Serum LD-1 activity in suspected acute myocardial infarction.
Authors: Gerhardt W , Hofvendahl S , Ljungdahl L , Waldenström J , Tryding N , Pettersson T , Ohlsson O 
Published: January 2020

Abstract
We have studied the diagnostic value of measuring lactate dehydrogenase (LD) isoenzyme 1 in serum of 331 cases of suspected acute myocardial infarction (AMI). At a discriminatory level of 200 U/L (Scandinavian Committee on Enzymes, recommended method for the determination of LD) LD 1 verified the diagnosis in 96% of the AMI cases and excluded it in 96% of the not-AMI cases when samples were drawn 24-72 h after onset of pain. The correlation between 24-h S-LD-1 and 16-h S-CK B activities was 0.94 in the AMI cases. We found that quantitation of serum LD-1 is diagnostically more reliable than the serum LD-1/LD ratio.
Quantitative enzyme antigen immunoassay of acetylcholinesterase in amniotic fluid.
Authors: Nørgaard-Pedersen B , Hangaard J , Bjerrum O J 
Published: January 2020

Abstract
An enzyme immunoassay for acetylcholinesterase in amniotic fluid is described. Rabbit antiserum (IgG fraction) against human erythrocyte membrane acetylcholinesterase is first attached to microtitre plates. Samples containing acetylcholinesterase are added and the enzyme activity is then measured, with acetylthiocholine as substrate and Ellman's reagent as coupling salt. Results are comparable with those by qualitative determination of the enzyme after polyacrylamide gel electrophoresis, except for blood-contaminated amniotic fluids. One person can perform 200 enzyme analyses per day. Intra- and interassay coefficients of variation are less than 5% at concentrations from 15 to 450 arb. units/L. The mean catalytic concentration in 400 amniotic fluid samples was 21 arb. units/L (range 5 to 70 arb. units/L) with 1000 arb. units/L for a human serum pool as standard. All 39 cases of neural tube defects and two-thirds of cases with omphalocele and gastroschisis had abnormally high values, exceeding 75 arb. units/L.
Liquid-chromatographic determination of nadolol in plasma.
Authors: Gupta R N , Haynes R B , Logan A G , Macdonald L A , Pickersgill R , Achber C 
Published: January 2020

Abstract
We describe a liquid-chromatographic procedure for determining nadolol in plasma. After an analog of nadolol is added as internal standard, the plasma sample is passed through a disposable BondElut C18 column. After several column washes, nadolol and the internal standard are eluted with methanol, and the eluate is evaporated and reconstituted with the mobile phase (acetonitrile/water, perchloric acid, and tetramethylammonium hydroxide). An aliquot of the extract is chromatographed on a non-silica resin-base reversed-phase column. The peaks are detected by fluorescence (lambda ex = 265 nm and lambda em = 305). Drug and internal standard are well resolved, and only a few extraneous peaks appear. The standard curve ranges from 10 to 400 micrograms/L. We are using this procedure to determine steady-state concentrations of nadolol in patients receiving various dosages of nadolol along with other types of antihypertensive drugs.
Three commercial methods for serum ferritin compared and the high-dose "hook effect" eliminated.
Authors: Ng R H , Brown B A , Valdes R 
Published: January 2020

Abstract
We evaluated four commercial kits for measuring serum ferritin, based on three techniques: immunoradiometric assay, radioimmunoassay, and enzyme immunoassay. The kits evaluated were those manufactured by Abbott Laboratories, Clinical Assays, Corning Medical, and Ramco. Two of the immunoradiometric kits showed satisfactory results with respect to sensitivity and precision; they should be useful in diagnosing individuals with uncomplicated iron-deficiency anemia. One of the immunoradiometric assay kits, however, showed a high-dose "hook effect," beginning at 10 mg of ferritin per liter. We modified this kit to eliminate this effect, at least to ferritin concentrations of 33 mg/L. (We observed a ferritin value as high as 47 mg/L in one patient.) Results with all these kits did not inter-compare well for ferritin concentrations greater than 300 micrograms/L, a finding that casts further doubt on the controversial use of serum ferritin measurement in cases of iron overload.
Effects of whole blood storage on results for glycosylated hemoglobin as measured by ion-exchange chromatography, affinity chromatography, and colorimetry.
Authors: Little R R , England J D , Wiedmeyer H M , Goldstein D E 
Published: January 2020

Abstract
After storage of whole blood at either 4 or 20 degrees C, results for glycosylated hemoglobin by ion-exchange chromatography ("high-performance" liquid and mini-column chromatography), thiobarbituric acid colorimetry, and affinity chromatography were compared. At 4 degrees C, all methods gave acceptable results for samples stored for as long as a week. At 20 degrees C, the colorimetric and affinity methods also showed sample stability for a week or more. The ion-exchange methods were associated with a marked increase in values for glycosylated hemoglobin after a few days of storage. Evidently, care in details of sample collection and handling is especially important for ion-exchange methods, and the colorimetric and affinity methods have advantages over ion exchange in situations where long delays between sample collection and assay are unavoidable.
New statistical approach in biochemical method-comparison studies by using Westlake's procedure, and its application to continuous-flow, centrifugal analysis, and multilayer film analysis techniques.
Authors: Gerbet D , Richardot P , Auget J L , Maccario J , Cazalet C , Raichvarg D , Ekindjian O G , Yonger J 
Published: January 2020

Abstract
In this paper, we present an application of Westlake's method (Biometrics 32:741, 1976) in method-comparison studies in clinical chemistry. The techniques under study are continuous flow (CF), centrifugal analysis (CA), and multilayer film analysis (the Kodak Ektachem procedure KE). The experimental data are for plasma calcium and serum uric acid. It results from a particular regression procedure proposed by York (Can J Phys 44:1079, 1966) that the usual regression comparison technique (joint testing procedure) is irrelevant because it rejects the identity hypothesis for the three methods, whereas fixing a tolerable upper limit deviation, delta, between two methods would lead to the conclusion that, in 95% of cases, CF and KE results are equivalent for plasma calcium (delta less than or equal to 45 mumol/L) and CF is roughly equivalent to the other two methods for serum uric acid (delta less than or equal to 27 mumol/L).
Graded hemagglutination inhibition for quantification of human fetal hemoglobin.
Authors: Wolk M , Kieselstein M 
Published: January 2020

Abstract
We describe a hemagglutination system for quantification of fetal hemoglobin (HbF), especially at low concentrations. This system consists of three components: (a) sheep erythrocytes coated with purified HbF, (b) sheep antiserum of human HbF made specific for the gamma-chain, and (c) human blood lysate with a known concentration of HbF as the standard. We can measure the whole range of HbF proportions in human blood, from 100% down to 0.01%. Statistical analysis showed that our measurements agreed with those made by the methods of alkali denaturation and radial immunodiffusion. Reproducibility of the method is shown by the low CVs for six repeated measurements. Low concentrations of HbF not measurable by other methods are easily assayed. We offer examples of the clinical utility of data on low concentrations of HbF.
Variations of 1-deoxyglucose(1,5-anhydroglucitol) content in plasma from patients with insulin-dependent diabetes mellitus.
Authors: Yoshioka S , Saitoh S , Negishi C , Fujisawa T , Fujimori A , Takatani O , Imura M , Funabashi M 
Published: January 2020

Abstract
The concentration of 1-deoxyglucose(1,5-anhydroglucitol) in plasma from patients with insulin-dependent diabetes mellitus was measured by gas-liquid chromatography with an all-glass capillary column. Twenty-one plasma samples were obtained from 21 patients before insulin therapy, and 34 more from 13 patients receiving insulin therapy. 1-Deoxyglucose was generally not detectable in plasmas of diabetic patients before they received insulin; it was measurable in the patients who had received insulin, although its concentration was low compared with that of healthy subjects. We therefore suggest that the absence of 1-deoxyglucose in plasma is one of the markers of metabolic states of diabetes, perhaps reflecting a disturbed function of carbohydrate metabolism; its presence in plasma within a normal range may reflect the better control of diabetic patients.
Enzymic creatinine assay: a new colorimetric method based on hydrogen peroxide measurement.
Authors: Fossati P , Prencipe L , Berti G 
Published: January 2020

Abstract
We describe a new colorimetric method for measuring creatinine in serum and urine. Creatinine hydrolysis is catalyzed by creatinine amidohydrolase, and the creatine so produced is assayed in reactions catalyzed sequentially by creatine amidinohydrolase and sarcosine oxidase in a system that generates hydrogen peroxide. The hydrogen peroxide is measured at 510 nm in a reaction catalyzed by horseradish peroxidase, with 3,5-dichloro-2-hydroxybenzenesulfonic acid/4-aminophenazone as the chromogen. This series of reactions is complete in 30 min at room temperature. A blank sample measurement corrects for endogenous creatine. The standard curve is linear for creatinine concentrations as great as 2.21 mmol/L. Analytical recovery of creatinine in human sera and urine averaged 99.8%. Within-run and between-run precision studies gave CVs of less than or equal to 3.3 and less than or equal to 4.3% for a serum with a creatinine concentration of 69 mumol/L. Results by this method agree well (r greater than 0.99) with those by both the enzymic ultraviolet method of Wahlefeld and the fuller's earth/Jaffé method.
Potentiometry of Na+ in undiluted serum and urine with use of an improved neutral carrier-based solvent polymeric membrane electrode.
Authors: Anker P , Jenny H B , Wuthier U , Asper R , Ammann D , Simon W 
Published: January 2020

Abstract
We present an improved Na+-selective liquid membrane electrode for measurement of Na+ concentrations in both undiluted serum and urine. The values for urinary Na+ obtained with the ion-selective electrode agree well with those obtained with the flame photometer. The correlation gives a standard residual deviation of +/- 2.7 mmol/L over the Na+ range of 25-280 mmol/L. In serum, this direct potentiometry yields Na+ concentrations 5.4% (SD 1.1%) higher than those obtained by atomic spectrometry and a standard residual deviation of +/- 1.1 mmol/L. Correction of these values for the volumes of protein and lipid leads to potentiometric values 1.2% (SD 0.7%) lower than those by flame photometry (residual standard deviation: +/- 1.0 mmol/L). Other factors that possibly contribute to this discrepancy are discussed.
Human placenta as a convenient source of creatine kinase BB.
Authors: Steghens J P , Maire I , Mathieu M 
Published: January 2020

Abstract
We demonstrate that human placenta is a convenient source of creatine kinase isoenzyme BB. We compare the physicochemical and catalytic properties with those of other creatine kinase isoenzymes: purified human abdominal muscle MM and brain BB. We also describe a stabilizing medium for creatine kinase BB. Human placental and brain BB have similar catalytic properties, the respective Km values for creatine phosphate being 0.66 and 0.56 mmol/L and for adenosine diphosphate 89 and 70 nmol/L.
Quantitation of haptens by homogeneous immunoprecipitation. 2. Centrifugal analysis for tobramycin, phenobarbital, and theophylline in serum.
Authors: Wu J W , Bunyagidj C , Hoskin S , Riebe S M , Aucker J , White K , O'Neill S P 
Published: January 2020

Abstract
Our homogeneous immunoprecipitation inhibition assay (Clin. Chem. 28:659-661, 1982) is applied here to tobramycin, phenobarbital, and theophylline. Only 10-50 microL of test sample is needed. No sample treatment, dilution, or extraction is required. A test serum sample is simultaneously mixed with a drug conjugate and its specific antiserum in a centrifugal analyzer. The subsequent reaction and the measurement are completed in 3 min. Within-run and between-run CVs for clinically relevant concentrations were well below 10%. Results for patients' samples correlated well with those by enzyme immunoassay.
Immunoassay techniques with fluorescent phycobiliprotein conjugates.
Authors: Kronick M N , Grossman P D 
Published: January 2020

Abstract
We describe immunoassay techniques that take advantage of the novel properties of phycobiliprotein fluorescent dyes. These dyes, which can be isolated from a wide variety of algae, exhibit extremely high absorptivities, high quantum efficiencies, and excitation and emission bands across the visible spectrum. These stable, hydrophilic proteins can easily be linked to antibodies by conventional protein cross-linking reagents. One assay technique presented here demonstrates the use of phycobiliproteins in a solid-phase "sandwich" assay, which achieves picomolar sensitivity. In the other technique the unique spectral properties of phycobiliproteins are applied to fluorescence excitation transfer immunoassay.
Evaluation of multi-wavelength derivative spectra for quantitative applications in clinical chemistry.
Authors: Weiser W E , Pardue H L 
Published: January 2020

Abstract
We have used the quantitation of methemoglobin in the presence of a light-scattering suspension as a model to evaluate and compare the relative merits of zeroth-, first-, and second-derivative spectroscopy for problems in clinical chemistry. Data for second derivatives are most effective in nullifying the effect of the background spectrum; data for first derivatives are less effective; and data for absorbance (zeroth derivative) are least effective. In one set of experiments, variable amounts of the light-scattering component were added to a methemoglobin solution to increase the apparent absorbance up to about 230% of the absorbance of the original solution. Whereas computation with data for absorbance would have yielded errors approaching 100%, concentrations computed with second-derivative spectral data yielded a systematic error (bias) of only 0.5% and a relative standard deviation (CV) of 1.6%.
Optical fiber fluoroprobes in clinical analysis.
Authors: Sepaniak M J , Tromberg B J , Eastham J F 
Published: January 2020

Abstract
We used quartz optical fibers and laser excitation in developing single-fiber fluoroprobes, to be used to measure molecular fluorescence in minute volumes of body fluids. We illustrate and discuss the analytical capabilities of these fluoroprobes. Limits of detection for the anti-tumor drug doxorubicin are about 10(-7) mol/L, by either conventional fluorescence or sequentially excited fluoroscence modes of detection. We also report the results of preliminary in vivo measurements of doxorubicin in the interstitial fluids of human tumors, heterotransplanted in immune-deficient laboratory mice.
An improved micro-scale liquid-chromatographic assay for piperacillin in plasma and urine.
Authors: Jung D , Mahajan N K 
Published: January 2020

Abstract
An accurate, sensitive, and specific liquid-chromatographic method is described for measuring piperacillin in plasma and urine. Plasma samples deproteinized with two volumes of acetonitrile containing 1.2 mg of the internal standard, p-nitrobenzene sulfonamide, per liter are centrifuged. The clear supernate is evaporated under nitrogen, and the residue is reconstituted in 50 microL of the mobile phase (32/68 by vol acetonitrile/water, adjusted to pH 2.5 with 85% phosphoric acid), of which 10 microL is injected onto a reversed-phase (C-18) column. Urine samples are diluted 10-fold with distilled water, an equal volume of acetonitrile containing 3 mg of the internal standard per liter is added, and 20 microL is chromatographed. Stability studies indicate that storage conditions are critical for both plasma and urine. Piperacillin in plasma is stable at -70 degrees C for at least six weeks, but 100% of it is degraded during the same time at -20 degrees C. Piperacillin in urine is also stable at -70 degrees C for six weeks, but 20% is degraded during six weeks at -20 degrees C.
Anti-triiodothyronine autoantibodies interfere with two recently commercialized radioimmunoassays for free triiodothyronine.
Authors: Rodríguez-Espinosa J , Ordóñez-Lianos J , Gómez-Gerique J A , Mora J 
Published: January 2020

Abstract
We examined the effect of anti-triiodothyronine autoantibodies on results of RIA of free triiodothyronine with two commercial kits (Amersham International and Diagnostic Products Corp.). Both methods gave falsely high results because the 125I-labeled analogs used in these RIAs were bound by the autoantibodies.
Amylase from human serous ovarian tumors: purification and characterization.
Authors: Zakowski J J , Gregory M R , Bruns D E 
Published: January 2020

Abstract
Human serous-type ovarian tumors contain an acidic isoenzyme of amylase. Previous attempts at purification of tumor amylases have yielded preparations contaminated with other proteins. The purification scheme presented here incorporates an affinity-chromatography procedure, with use of cycloheptaamylose linked to epoxy-activated Sepharose, that is specific for alpha-amylase (EC 3.2.1.1). Purified amylase isoenzyme from a human serous ovarian tumor was characterized and compared with the purified salivary and pancreatic isoenzymes. All three were similar in amino acid composition, pH optimum, substrate specificity, calcium requirement, heat inactivation, and Km for maltotetraose substrate. The ovarian tumor amylase was similar to the salivary and distinct from the pancreatic enzyme by apparent molecular mass and doublet formation on sodium dodecyl sulfate--polyacrylamide electrophoresis, specific activity of pure enzyme, and sensitivity to specific alpha-amylase inhibitors. All three isoenzymes differed in net electrical charge as evidenced by diethylaminoethyl-Sephadex ion-exchange chromatography and isoelectric focusing. The tumor amylase is clearly distinct from the pancreatic and differs from the salivary enzyme in net electrical charge. Evidence is presented that this charge difference may reflect, at least in part, deamidation of an amylase that is similar to or identical with salivary amylase.
Noncompetitive enzyme-linked immunoassay for apolipoprotein B in serum.
Authors: Fievet C , Koffigan M , Ouvry D , Marcovina S , Moschetto Y , Fruchart J C 
Published: January 2020

Abstract
We used a noncompetitive enzyme-linked immunoassay to measure apolipoprotein B (apo-B) concentration in human plasma. Goat anti-lipoprotein B immunoglobulins were adsorbed to the surface of polystyrene balls. After washing, this solid-phase antibody was incubated with antigen (plasma from normal or hyperlipoproteinemic fasting subjects), washed, and then incubated with peroxidase-labeled goat anti-lipoprotein B IgG. After a last washing, we measured the bound label, which provided a direct measurement of the antigen. Under optimized assay conditions, the minimum detectable concentration was 50 ng per assay. The assay may be used to measure apo-B in different lipoprotein fractions (low- or very-low-density) and yields values that compared favorably with those obtained by electroimmunoassay (r = 0.86). The assay offers several advantages over existing techniques: sensitivity, specificity, simplicity, avoidance of radioisotopes, and potential for use with monoclonal antibodies.
On-line computer analysis of chemiluminescent reactions, with application to a luminescent immunoassay for free cortisol in urine.
Authors: Tommasi A , Pazzagli M , Damiani M , Salerno R , Messeri G , Magini A , Serio M 
Published: January 2020

Abstract
We interfaced a microcomputer on-line with a luminometer to acquire the light signal of chemiluminescent reactions from a photomultiplier and then compute significant parameters of light emission and kinetic "shape" indices. Using this system to study interferences from biological samples on the measurement of chemiluminescent reactions, we observed that such effects are usually associated with modifications of the shape of the light-emission kinetics. These results suggest that a simultaneous evaluation of the shape of a chemiluminescent reaction and the measurement of light emission can be combined to assess luminescent immunoassays as an internal control of the interferences in measurements of the chemiluminescent tracer. As an example of this approach, we developed and validated a luminescent immunoassay for free cortisol in diluted urine. Dextran-coated charcoal is used for bound-free separation.
Determination of polyols in serum by selected ion monitoring.
Authors: Roboz J , Kappatos D C , Greaves J , Holland J F 
Published: January 2020

Abstract
We used gas chromatography-chemical ionization mass spectrometry with selected ion monitoring of the (M-59)+ ions to determine polyols (as their peracetyl derivatives) in serum. The internal standard was 2-deoxygalactitol. Mean (and SD) polyol concentrations (mg/L) in 33 normal sera were: erythritol 0.45 (0.14), threitol 0.20 (0.06), adonitol 0.06 (0.02), arabinitol 0.37 (0.12), xylitol 0.05 (0.02), mannitol 0.41 (0.45), galactitol 0.15 (0.11), sorbitol 0.16 (0.11). Arabinitol determined in the same 33 normal sera by trimethylsilylation was 0.39 (0.13) mg/L. In 32 samples from cancer patients with normal creatinine, all polyol concentrations were in the normal range except for seven increased erythritol and one increased threitol concentrations. In all six patients with renal dysfunction we found increased erythritol and arabinitol, and increased threitol and mannitol in four of the six. Initial results showed that only arabinitol concentrations increased in invasive candidiasis.