bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid-chromatographic measurement of riboflavin in serum and urine with isoriboflavin as internal standard.
Authors: Lambert W E , Cammaert P M , De Leenheer A P 
Published: January 2020

Abstract
We describe how riboflavin can be precisely and accurately measured in serum and urine. A structural analog, isoriboflavin, is used as an internal standard. Urine samples are prepared by adding the internal standard and trichloroacetic acid. For serum, proteins are denatured with trichloroacetic acid. A simple Sep-pak treatment of the supernate removes contaminating interferents. Within- and between-run precision is reflected by respective CVs of 2.2 and 4.9% for urine at 180 micrograms/L and 4.4 and 7.3% for serum at 10 micrograms/L. The standard curve is linear far beyond the concentrations encountered in serum and urine. The detection limit is estimated to be 10 micrograms/L and 1 microgram/L for urine and serum, respectively. The normal reference interval, as determined from 50 results for each matrix, is 36 to 349 micrograms/g of creatinine (mean 112 micrograms/g) for urine and 5.5 to 14.4 micrograms/L (mean 8.8 micrograms/L) for serum. Both distributions are skewed. The method is suited for routine use.
A highly sensitive immunoassay system involving antibody-coated tubes and liposome-entrapped dye.
Authors: O'Connell J P , Campbell R L , Fleming B M , Mercolino T J , Johnson M D , McLaurin D A 
Published: January 2020

Abstract
In this colorimetric immunoassay for digoxin, large, unilamellar phospholipid vesicles approximately 0.2 micron in diameter are loaded with high concentrations of Sulforhodamine B. Digoxigenin coupled to phosphatidylethanolamine, incorporated into the lipid formulation, confers immunological specificity. The liposomes are then used as tracers in simple competitive-binding immunoassays with antibody-coated tubes. Results are amplified by 10(3) to 10(4) of what could be achieved with one label group attached to each hapten, so that the results can be read spectrophotometrically. The stability of the liposomes is excellent. The method should be applicable to measuring a wide variety of analytes.
"The Yellow IRIS" urinalysis workstation--the first commercial application of "automated intelligent microscopy".
Authors: Deindoerfer F H , Gangwer J R , Laird C W , Ringold R R 
Published: January 2020

Abstract
Since 1982, "automated intelligence microscopy" (AIM) has been refined and adapted to perform the portion of the urinalysis profile traditionally done by a microscope. AIM and analytical subsystems measuring relative density and performing dipstick chemistry compose the main elements of "The Yellow IRIS" urinalysis workstation, an attended system for automation and standardization of routine urinalysis. Performance data gathered at three laboratory test sites show AIM to be analytically consistent over the required range of particulate enumeration, and show that it detects 20% more abnormalities than by conventional microscopy, and with greater precision (CVs 5 to 20%). Complete urinalysis, including the microscopic examination, requires little more than 1 min for normal specimens, 3 min for most abnormal specimens. Actual throughput rate varies with the particulate composition of specimens; typically, it averages greater than 30 specimens per hour, a 300% improvement in urinalysis productivity by CAP standards and an almost 500% improvement when typical emergency-use demands are taken into account.
Determinations of immunoglobulins G, A, and M in the Technicon RA-1000.
Authors: Ng R H , Altaffer M , Statland B E 
Published: January 2020

Abstract
We evaluated the Technicon RA-1000 "Random Access" analyzer for the measurements of immunoglobulins G, A, and M in serum by turbidimetry. For various concentrations of serum pools the total CV ranged from 3.0 to 4.5% for IgG, from 3.1 to 3.2% for IgA, and from 4.8 to 5.4% for IgM. The linearity of the standard curves was good in the clinically useful ranges. Results for patients' samples correlated well with those determined with the Beckman Auto ICS (rate nephelometric method). Normal reference intervals (based on data for 200 healthy blood donors) are 7.67 to 16.87 g/L for IgG, 0.87 to 3.89 g/L for IgA, and 0.61 to 2.70 g/L for IgM. The RA-1000 requires only 8 microL for all three tests and can analyze 25 specimens for all three proteins in 37 min. Compared with other methods for immunoglobulin assays, the RA-1000 has higher throughput and offers significant savings in labor and reagent costs.
Determination of total protein in human milk: comparison of methods.
Authors: Keller R P , Neville M C 
Published: January 2020

Abstract
We evaluated four spectrophotometric methods for suitability in determining total protein in human milk samples. Results were compared with those by an established method for the determination of total nitrogen (micro-Kjeldahl). Values for total protein by all four methods significantly correlated with micro-Kjeldahl. For the biuret assay, Lowry-Peterson assay, Bio-Rad Coomassie Blue assay, and Pierce BCA assay, the correlation coefficients were 0.96, 0.97, 0.89, 0.99, respectively. We also assessed the sensitivity of each assay to several purified human milk proteins. The Pierce BCA assay showed the least difference in values among different types of protein. For this reason, and because it showed the greatest precision (with acceptable constant and proportional error), we recommend the BCA method.
The EPOS Automated Selective Chemistry Analyzer evaluated.
Authors: Moses G C , Lightle G O , Tuckerman J F , Henderson A R 
Published: January 2020

Abstract
We evaluated the analytical performance of the EPOS (Eppendorf Patient Oriented System) Automated Selective Chemistry Analyzer, using the following tests for serum analytes: alanine and aspartate aminotransferases, lactate dehydrogenase, creatine kinase, gamma-glutamyltransferase, alkaline phosphatase, and glucose. Results from the EPOS correlated well with those from comparison instruments (r greater than or equal to 0.990). Precision and linearity limits were excellent for all tests; linearity of the optical and pipetting systems was satisfactory. Reagent carryover was negligible. Sample-to-sample carryover was less than 1% for all tests, but only lactate dehydrogenase was less than the manufacturer's specified 0.5%. Volumes aspirated and dispensed by the sample and reagent II pipetting systems differed significantly from preset values, especially at lower settings; the reagent I system was satisfactory at all volumes tested. Minimal daily maintenance and an external data-reduction system make the EPOS a practical alternative to other bench-top chemistry analyzers.
Biological variance of cholinesterase and 5'-nucleotidase in serum of healthy persons.
Authors: Moses G C , Tuckerman J F , Henderson A R 
Published: January 2020

Abstract
We measured cholinesterase (EC 3.1.1.8) and 5'-nucleotidase (EC 3.1.3.5) activities in serum of 24 healthy laboratory staff during 12 months. Overall mean activities ranged from 5.3 to 13.4 kU/L for cholinesterase and 5.4 to 9.8 U/L for 5'-nucleotidase. Cholinesterase activity was significantly (p less than 0.01) higher for men than for women. 5'-Nucleotidase activity was significantly (p = 0.01) higher for subjects 40 years or older than for those younger than 40, but was not different with respect to sex or time of year. Average intra- and interindividual variances (SD2) were 0.38 and 2.69 for cholinesterase and 1.41 and 0.97 for 5'-nucleotidase, respectively. Intra- to interindividual standard deviation ratios were 0.38 for cholinesterase and 1.21 for 5'-nucleotidase. Average within-run analytical variances were 0.13 and 0.3 (4% and 13% of total variance) for cholinesterase and 5'-nucleotidase, respectively. The importance of these findings in regards to diagnostic interpretation of serum cholinesterase and 5'-nucleotidase results is discussed.
In vitro oxidation of uric acid in serum by methylene blue.
Authors: Andranovich T , Kelner M J 
Published: January 2020

Abstract
Methylene blue oxidizes uric acid to allantoin in vitro, analogous to the reaction between uric acid and phosphotungstate, although the rate is considerably slower. The reaction requires oxygen and produces hydrogen peroxide. As little as 10 micromol of methylene blue per liter in a serum sample will produce a measurable difference in the apparent uric acid concentration within 4 h at room temperature. Methylene blue may be administered for various medical reasons. If uric acid is to be measured in such sera, the procedure should be performed within 30 min, whatever method of analysis is used.
Clinical and analytical evaluation of kits for measurement of creatine kinase isoenzyme MB.
Authors: Koch T R , Mehta U J , Nipper H C 
Published: January 2020

Abstract
We studied the analytical and clinical performance of six methods for creatine kinase (EC 2.7.3.2) isoenzyme MB (CK-MB): three immunoassays (Behring, Hybritech, and International Immunoassay Labs); one immunoinhibition assay (Roche); one immunoinhibition/column method (Du Pont); and one electrophoretic method (Beckman). Between-day precision for all kits was poor at the upper reference limit. All methods gave results linearly related to CK-MB concentration and all were free from CK-MM, CK-BB, and adenylate kinase interference. Only the Du Pont method was adversely affected by atypical isoenzymes. For diagnosis of acute myocardial infarction in a coronary care population (n = 40; prevalence = 45%), all methods were approximately 95% efficient, when appropriate reference criteria were used. Some manufacturers fail to provide data for an appropriate (acutely ill, non-infarct) reference population; decreased diagnostic specificity may result from use of reference ranges based on results for healthy subjects. Expression of CK-MB as a percent of total CK degrades efficiency unless total CK is markedly increased.
Factors affecting determination of delta-aminolevulinate by use of Ehrlich's reagent.
Authors: Tomokuni K , Hirai Y 
Published: January 2020

Abstract
We investigated the formation of delta-aminolevulinic acid (ALA)-pyrrole and subsequent color development used in determining ALA in urine. Of three condensation reagents examined--acetylacetone, ethyl acetoacetate, and methyl acetoacetate--the last was the best. When the ALA-pyrrole is reacted with Ehrlich's reagent in ethyl acetate according to one procedure, the optimum concentration of perchloric acid in the reagent is 0.5 to 1.0 mol/L. Its optimum concentration is 1.0 to 2.3 mol/L when the reaction takes place in water.
Digoxin--issues and controversies.
Authors: Soldin S J 
Published: January 2020

Abstract
This review deals briefly with the clinical pharmacology of digoxin and reviews in some depth the problems inherent in methods of digoxin measurement. Digoxin-like factors (materials that cross react in digoxin immunoassays) are discussed, and some current evidence suggesting the existence of a new hormone, endoxin (endogenous digoxin), is summarized.
Concentration of glucocorticoid receptor sites in normal human lymphocytes.
Authors: Steiner A E , Wittliff J L 
Published: January 2020

Abstract
We used a whole-cell glucocorticoid receptor assay to examine characteristics of the glucocorticoid receptor in the lymphocytes of normal human donors. We measured binding of [3H]dexamethasone to the lymphocytes of four different donors on several different occasions; the variation about the mean for the assays was +/- 15%. Whole-cell assays in 15 normal subjects showed a mean value of 6.18 fmol/10(6) cells or 3722 sites per cell, with a somewhat higher level in men (7.67 fmol/10(6) cells, or 4620 sites per cell) than women (4.48 fmol/10(6) cells, or 2698 sites per cell). We saw no correlation between donor age and receptor values, in either group. Assays in which we used [3H]prednisolone demonstrated similar binding properties as with [3H]dexamethasone. The mean glucocorticoid receptor value for normal human T-cells from three donors was 2.52 fmol/10(6) cells, or 1518 sites per cell.
Specific interaction between antidigoxin antibodies and digoxin-like immunoreactive substances in cord serum.
Authors: Scherrmann J M , Sandouk P , Guedeney X 
Published: January 2020

Abstract
Digoxin-like immunoreactive substances (DLIS) have been quantified by two different digoxin radioimmunoassays (RIA) in 47 cord sera. The mean DLIS value (in digoxin equivalents) ranged from 0.960 (SD 0.184) to 0.181 (SD 0.104) nmol/L between the two different kits and different lot numbers of the reagents. One of the RIA methods showed an obvious lot-to-lot effect. The use of a longer incubation interval and a higher incubation temperature markedly decreased cross reactions with DLIS. The effect of modifying the incubation conditions in RIA is similar to that described for assays of steroids because the dissociation rates of the immunocomplex play a critical role. Data suggest a specific interaction between DLIS and digoxin antibodies. Control of the incubation conditions is recommended, to decrease or increase the amount of the DLIS in cord serum specimens.
Determination of urinary lysozyme for potential detection of tubular dysfunction in diabetic nephropathy.
Authors: Shima K , Hirota M , Fukuda M , Tanaka A 
Published: January 2020

Abstract
Seeking to study whether measurement of lysozyme (EC 3.2.1.17) in urine by a reliable radioimmunoassay can provide a suitable index of renal tubular function and how lysozymuria develops in temporal relation to proteinuria in diabetic nephropathy, we have compared the urinary excretion of lysozyme and beta 2-microglobulin with the 15-min excretion rate of phenolsulfonphthalein in 39 patients with Type 2 (non-insulin-dependent) diabetes and investigated the temporal relation between the onset of lysozymuria and proteinuria in 15 patients with Type 1 (insulin-dependent) diabetes. The concentrations of lysozyme and beta 2-microglobulin in urine increased in proportion to the decrease in the rate of excretion of phenolsulfonphthalein in these patients. The coefficient of correlation between lysozyme concentration and the 15-min excretion rate of phenolsulfonphthalein (r = -0.70) was higher than that between beta 2-microglobulin concentration and the 15-min excretion rate of phenolsulfonphthalein (r = -0.46). Abnormally high lysozymuria, suggesting the existence of tubular dysfunction, was demonstrated in six of the patients with Type 1 diabetes who showed no proteinuria or only a slight increase in urinary protein excretion. Lysozymuria may thus be added to a list of the indicators for diabetic nephropathy.
Measurement of hemoglobin A1c by a new liquid-chromatographic assay: methodology, clinical utility, and relation to glucose tolerance evaluated.
Authors: Jeppsson J O , Jerntorp P , Sundkvist G , Englund H , Nylund V 
Published: January 2020

Abstract
A chromatographic method for determining glycated hemoglobin (Hb A1c) by use of a new monodisperse cation-exchanger has been investigated. Hb A1c was separated from other "minor hemoglobins": Hb F, Hb A3 (the glutathione adduct), and the acetaldehyde adduct in alcoholics. The method was fully automated and a single column could be used for more than 1000 runs. The normal reference interval was 4.0-5.2%; the interval for diabetic outpatients was 5.6-12.4%. Within-run and the between-run CVs were less than 0.9% and 1.7%, respectively. Carbamylation in uremic patients who were undergoing hemodialysis increased the proportion of Hb A1c to 1%. Hb A1c results were compared with results from glucose tolerance tests. In our study, Hb A1c less than 5.5% excluded diabetes: subjects with Hb A1c greater than 6.2% showed diabetes. If blood sampled during fasting had been screened with determinations of glucose and Hb A1c, only 20% of referred subjects would have needed an oral glucose tolerance test for diagnosis of diabetes.
External quality assessment of assays of lead in blood.
Authors: Bullock D G , Smith N J , Whitehead T P 
Published: January 2020

Abstract
The operation and results of the United Kingdom External Quality Assessment Scheme for Lead in Blood, which currently has about 140 participants within and outside the U.K. are described. The choice of specimens, scheme design, and scoring of performance are discussed, as is the validity of the consensus values used as a basis for the scoring. There has been a continued improvement in performance as assessed by this program, some of which appears to have been stimulated by the introduction of Variance Index scoring. The relative performance of the methods for assaying lead in blood is also examined.
Evaluation of a quantitative immunoturbidimetric assay for rheumatoid factors.
Authors: Melamies L M , Ruutsalo H M , Nissilä H 
Published: January 2020

Abstract
A quantitative immunoturbidimetric assay for rheumatoid factors (RF) is described, based on the immunoprecipitation between aggregated human IgG and rheumatoid factors in serum. The resulting turbidity is measured photometrically at 340 nm. The method is standardized against the WHO international reference preparation and the results are expressed in international units per milliliter (int. units/mL). Results correlate well with those by different latex-agglutination techniques (r = 0.80-0.96). The correlation with Waaler-Rose test modifications were 0.75 and 0.92. The within-run and between-run coefficients of variations were respectively from 1.2 to 2.6% and 1.3 to 1.9% for high and low RF concentrations. Quantitative and reproducible results, together with high throughput of samples and compatibility with most clinical chemistry analyzers and photometers, make this new assay well suited for routine screening and monitoring of rheumatoid factors.
Direct chemiluminescence immunoassay for estradiol in serum.
Authors: De Boever J , Kohen F , Usanachitt C , Vandekerckhove D , Leyseele D , Vandewalle L 
Published: January 2020

Abstract
In this simple, reliable, fast solid-phase chemiluminescence immunoassay for directly measuring (i.e., without prior extraction) estradiol-17 beta in serum, a monoclonal antibody is used that binds estradiol with high affinity (Ka = 10(10) L/mol), and does not bind other steroids tested, the highest cross reactivity observed being 0.1% for estradiol-17 alpha. In this system the monoclonal antibody is bound to the wells of microtiter plates via a second antibody directed against the monoclonal antibody. Fifty microliters of serum and estradiol-displacing agents are added, followed by 100 pg of estradiol-isoluminol conjugate, and the label is measured by luminometry after the binding reaction. The sensitivity of the assay is 180 pmol per liter of serum, and the effective working range at less than or equal to 10% CV is 270 to 6700 pmol/L. Analytical recovery of added estradiol averaged 99.7% (SD 6.5%). Within- and between-assay CVs ranged between 5 and 12.7%. Thirty-five unknown serum samples can be assayed within 4 h. Results correlated well with those obtained with a direct RIA: r = 0.94 (n = 149). This assay opens new perspectives for chemiluminescence immunoassays.
Total urinary estriol determined by "on-line" liquid chromatography with ultraviolet detection.
Authors: Schöneshöfer M , Dhar T K , Ioanides D 
Published: January 2020

Abstract
We report a fully automated method for the specific assessment of total estriol in urine. Acid-hydrolyzed urine is concentrated on a short reversed-phase column and prepurified with methanolic Tris buffer, the pH of the buffer increasing from 7 to 11. The anionic form of the estriol molecule is eluted with methanolic NaOH. By acidification in a mixing chamber, estriol in its neutral form is focused on the top of a second short reversed-phase column, effectively chromatographed on an analytical column, and quantified by ultraviolet absorbance at 278 nm. Losses of estriol throughout the total procedure are negligible and thus external calibration is feasible for quantification. Analytical recoveries for estriol-supplemented urines ranged from 98.3 to 105%. Replicate analyses of a urine containing 68 mumol of estriol per liter gave a CV of 2.76%. As little estriol as 2 mumol/L can be detected. Results from pregnancy urines correlated well with those of radioimmunoassay. The method is especially suited for clinical emergencies in a routine laboratory.
Quantification of bone alkaline phosphatase in serum by precipitation with wheat-germ lectin: a simplified method and its clinical plausibility.
Authors: Behr W , Barnert J 
Published: January 2020

Abstract
We report an easy, rapid method for quantifying bone isoenzyme of alkaline phosphatase (EC 3.1.3.1., ALP) in serum. The original method described by Rosalki and Ying Foo (Clin Chem 1984;30:1182-6) was somewhat simplified. In contrast to their results, we found that bone ALP is precipitated quantitatively by wheat-germ lectin. To check the clinical plausibility of the method, we used samples from several comparison groups (blood donors, children, pregnant women, patients with neoplasms but without skeletal involvement) and a large number of patients suffering from bone diseases and diseases of the liver and biliary tree. Measured activities of bone ALP nearly always correlated with the clinical diagnosis. Only patients with hepatitis often had pathological bone activities not in accord with the other findings. Possible reasons for this observation are discussed.
Extending the linear range for kinetic reactions by considering the relationship between enzyme activity of the reagent and measurement intervals.
Authors: Goren M P , Davis J E 
Published: January 2020

Abstract
We show that the rate-concentration curve is sigmoidal for enzyme-catalyzed procedures that are commonly applied to rapid automated analyzers. Linear data can be obtained by judicious selection of the reagent enzyme activity (Vm) and the measurement interval (t1 to t2). For determination of substrate concentrations much less than Km, conditions that balance linearity with sensitivity and accuracy are obtained when Vm/Km = [ln (t2/t1)]/(t2-t1). We also present theoretical and experimental data that show the linear range can be extended to concentrations exceeding the Km value. We illustrate the application of theoretically appropriate conditions by analysis of procedures reported to be optimized. Familiarity with these concepts can obviate laborious and potentially misleading experimentation.
Simultaneous liquid-chromatographic determination of 3,4-dihydroxyphenylglycol, catecholamines, and 3,4-dihydroxyphenylalanine in plasma, and their responses to inhibition of monoamine oxidase.
Authors: Eisenhofer G , Goldstein D S , Stull R , Keiser H R , Sunderland T , Murphy D L , Kopin I J 
Published: January 2020

Abstract
This is a reversed-phase liquid-chromatographic method, with electrochemical detection, for simultaneously measuring, in plasma, the concentrations of the catecholamine precursor dihydroxyphenylalanine (DOPA); the endogenous catecholamines norepinephrine, epinephrine, and dopamine; and the deaminated catecholamine metabolites dihydroxyphenylacetic acid (DOPAC) and dihydroxyphenylglycol (DHPG). We used this method to assess effects of monoamine oxidase (EC 1.4.3.4) inhibition in humans. Plasma DHPG concentrations as determined by the present method (mean 826, SEM 61 ng/L) were similar to those found by other methods. Inhibition of monoamine oxidase (by administering deprenyl or tranylcypromine) decreased plasma DHPG by greater than 65%, plasma DOPAC by greater than 50%, and plasma DOPA by about 20%, without consistently affecting norepinephrine or epinephrine. Simultaneous measurement of DOPA, catecholamines, and DHPG may be useful for examining the synthesis, release, and intraneuronal metabolism of norepinephrine. The assay method is rapid, reliable, and simple, and it provides a more comprehensive assessment of noradrenergic nervous function than does measurement only of catecholamines.