bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent advances in measurement of amylase activity--a comparative study.
Authors: Kaufman R A , Tietz N W 
Published: January 2020

Abstract
We evaluated four kinetic amylase procedures with respect to kinetics, analytical range, blank rates, reagent stability, reagent impurities, interfering substances, and intrinsic sensitivities. Each of the methods is shown to have its own unique advantages and disadvantages. A preliminary discussion of some alternative methods, in which glycosidic p-nitrophenyl alpha-oligosaccharides are substrates, is included.
Creatine kinase radioimmunoassay and isoenzyme electrophoresis compared in the diagnosis of acute myocardial infarction.
Authors: Homburger H A , Jacob G L 
Published: January 2020

Abstract
We compared, in 116 patients, the relative usefulness of results of tests for creatine kinase B isoenzymes, as measured by radioimmunoassay, and the MB isoenzyme, as measured by electrophoresis, in diagnosis of acute myocardial infarction. The radioimmunoassay was specific for isoenzymes of creatine kinase containing the B subunit. All patients with acute transmural infarcts had positive test results by both techniques, but concentrations of B-isoenzymes were more frequently above normal than were MB bands in the case of patients with acute subendocardial infarcts and in the case of all patients with acute myocardial infarcts from whom sera were collected more than 24 h after onset of chest pain. Concentrations of B-isoenzymes also were increased, even when MB bands were not electrophoretically detectable, in specimens from several patients without documented actue myocardial infarcts. These abnormal results presumably were caused by increased concentrations of the BB isoenzyme in serum. Accordingly, an increased concentration of B-isoenzymes had less diagnostic specificity and predictive value for acute myocardial infarction than did a detectable MB band. Results of isoenzyme electrophoresis were more reliable for establishing this diagnosis, but the results of radioimmunoassay were more reliable for excluding it in patients with chest pain as the primary symptom.
A semi-automatic enzymic method for estimating urinary oxalate.
Authors: Yriberri J , Posen S 
Published: January 2020

Abstract
A two-enzyme method is presented for estimating urinary oxalate by continuous-flow analysis. Oxalate is decarboxylated, yielding formate, which is subsequently oxidized in the presence of NAD+, yielding NADH. The NADH, measured colorimetrically, is proportional to the amount of oxalate originally present in the sample. Urine is pretreated by precipitation of the oxalate and extraction of the precipitate in citrate buffer. A correction factor for the extraction efficiency is given by the recovery of [U-14C]oxalic acid added to aliquots of the 24-h urine specimen. The normal range obtained by this method was 0.20 to 0.52 mmol/24h (18 to 47 mg/24h) with a mean value of 0.37 mmol/24 h (33 mg/24h). The between-assay CV was 7.6% (n = 12), within-assay CV 3.2% (N = 25). Unlabeled oxalate (0.5 and 1.0 mol/L) added to 28 urine samples gave a mean analytical recovery of 95% (SD 10%).
Acid Phosphatase in Gaucher's Disease
Authors: Robinson Douglas B , Glew Robert H 
Published: January 2020

Abstract
Vol. 26
p 374: Second column, line 1: "designated," not "designed."
p 457: First line of abstract: correct number is "2.7.3.2"; second paragraph under "Serum Samples": "mammary artery," not "mammary vein."
p 458: Under "Column Chromatography," line 9 to read "buffer (200 mmol/L NaCl, 50 mmol/L Tris-HCl)..." Sublegend to Figure 1: add "a, concentration gel; b, separation gel." Under "Isoelectric Focusing," line 6 should read "7 mg of ammonium persulfate, 0.1 mL of pH 4-6 carrier ampholyte, and 0.1 mL of pH 5-7 ampholyte."
p 485:last paragraph: insert "98" before "(29.4%)," delete "low value," change "(6.5%)," to "(6.3%)," and change "µ/L" to "µg/L."
Effect of cations on the human creatine kinase isoenzymes.
Authors: Nealon D A , Henderson A R 
Published: January 2020

Abstract
We report our findings on the effect of Ca2+, K+, Na+, Fe2+, Mn2+, Zn2+, and Cu2+ on the activity of creatine kinase isoenzymes derived from human tissues. The only inhibitory cation was Ca2+, and Dixon plots of the data indicate the inhibition to be competitive for the Mg2+ in the reaction assay mixture. This effect of Ca2+ on all three isoenzymes is completely reversed by including Mg2+ (10 mmol/L) and ethylenediaminetetraacetate (2 mmol/L) in the assay mixture. Our findings suggest that it is unnecessary to add chelators to the patient's sample.
Estrogen radioimmunoassay suitable for the monitoring of ovulation induction.
Authors: Ashby C D , Danzer H C , Swerdloff R S 
Published: January 2020

Abstract
A rapid radioimmunoassay for estrogen in serum was characterized and validated. Analytical recoveries of estrone and estradiol were essentially 100%; estriol was not measured because it was eliminated by sample-handling procedures. Nonspecific interference from serum extracts, which was initially reflected by positive blanks, was eliminated by a sodium hydroxide wash of the extract. Validation of the procedure included determination of a reference interval for estrogen that agreed with the sum of estradiol and estrone concentrations reported in the literature for eugonadal women. Clinical applicability of the assay was demonstrated by monitoring estrogen concentrations during the menstrual cycle and during urogonadotropin (Pergonal)-induced follicular maturation. Because of its rapid turnaround time, the assay is ideally suited for monitoring the frequency with which urogonadotropin should be administered to the infertile patient, and the dosage, thus decreasing the likelihood of multiple pregnancies or ovarian hyperstimulation.
Muscle protein analysis. II. Two-dimensional electrophoresis of normal and diseased human skeletal muscle.
Authors: Giometti C S , Bárány M , Danon M J , Anderson N G 
Published: January 2020

Abstract
We used high-resolution two-dimensional electrophoresis to analyze the major proteins of normal and pathological human-muscle samples. The normal human-muscle pattern contains four myosin light chains: three that co-migrate with the myosin light chains from rabbit fast muscle (extensor digitorum longus), and one that co-migrates with the light chain 2 from rabbit slow muscle (soleus). Of seven Duchenne muscular dystrophy samples, four yielded patterns with decreased amounts of actin and myosin relative to normal muscle, while three samples gave patterns comparable to that for normal muscle. Six samples from patients with myotonic dystrophy also gave normal patterns. In nemaline rod myopathy, in contrast, the pattern was deficient in two of the fast-type myosin light chains.
Quantitative analysis for tricyclic antidepressant drugs in plasma or serum by gas chromatography-chemical-ionization mass spectrometry.
Authors: Chinn D M , Jennison T A , Crouch D J , Peat M A , Thatcher G W 
Published: January 2020

Abstract
We describe a gas chromatographic-chemical-ionization mass spectrometric procedure for determining concentrations of the tricyclic antidepressant drugs and their demethylated metabolites in plasma. The procedure requires 2.0 mL of plasma or serum and involves internal standard addition, extraction with a mixed organic solvent, and separation on a column packed with 0.5% potassium hydroxide and 2% Carbowax 20M. Between-assay and within-assay (n = 10) CVs were less than 11.0%. The procedure has been applied to several interesting cases, three of which are summarized.
Two new non-barbiturate buffers for electrophoresis of serum proteins on cellulose acetate membranes.
Authors: Ambler J , Rodgers M 
Published: January 2020

Abstract
Two new non-barbiturate buffers have been formulated for serum protein electrophoresis on cellulose acetate membranes. Both buffers give five distrinct fractions and are suitable for all systems, but have been primarily designed to meet the needs of the Gelman "Sepratek" system. One buffer is a tris(hydroxymethyl)aminomethane (Tris)/hippurate formulation; the other is composed of Tris/N-[tris(hydroxymethyl)methyl]glycine (Tricine)/sodium chloride/sodium salicylate. Both buffers allow reliable quantitation of protein fractions, giving results that correlated well with those obtained from barbiturate separations. The major advantage of these buffers is that they do not contain drugs of abuse.
Serum enzymes and isoenzymes in the diagnosis and differential diagnosis of myocardial ischemia and necrosis.
Authors: Lott J A , Stang J M 
Published: January 2020

Abstract
Diagnosis of injury to the myocardium is facilitated by information on the activities of creatine kinase (EC 2.7.3.2) MB isoenzyme (CK-MB) and lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 in serum, thee isoenzymes being present in higher activities in the myocardium than in other tissues or in normal serum. The temporal relationships of these isoenzymes, total creatine kinase, total lactate dehydrogenase, and aspartate aminotransferase (EC 2.6.1.1) are highly sensitive and specific for acute injury to the heart, particularly acute myocardial infarction. Chronic heart diseases, electric cardioversion for heart rhythm disturbances, coronary catheterization, and exercise usually do not produce increases of CK-MB, although abnormal aspartate aminotransferase, creatine kinase, lactate dehydrogenase, and lactate dehydrogenase isoenzyme 1 activities are seen in some individuals. Many other causes of increased activities of these enzymes and isoenzymes in serum are unrelated to injury to the heart. Because CK-MB is present in the skeletal muscle in low activities, substantial injury to skeletal muscle can increase CK-MB activities in the blood to abnormal values. Pulmonary embolism can mimic myocardial infarction in its clinical presentation. In patients with an accurately known time of onset of symptoms and serial enzyme analysis every 12 h during the first 48 h, acute myocardial infarction can be distinguished from pulmonary embolism by determinations of creatine kinase, CK-MB, aspartate aminotransferase, and lactate dehydrogenase isoenzyme 1 in serum.
An optimized assay of alanine aminopeptidase activity in urine.
Authors: Jung K , Scholz D 
Published: January 2020

Abstract
Elaboration of an optimized kinetic test for urinary alanine aminopeptidase at 37 degrees C is described. As final concentrations, 50 mmol/L tris(hydroxymethyl)aminomethane x HCl buffer, pH 7.8, and 2 mmol/L alanine-4-nitroanilide are proposed. Five- to sixfold activitiy is obtained as compared with a generally used test procedure. Coefficients of variation for the method (within-run and between-day precision) ranged from 1.56 to 3.45%. Men excreted more alanine aminopeptidase than did women if urinary volume or urinary timed volume was used as basis of reference. We saw no sex-related differences in excretion of alanine aminopeptidase when enzyme excretion was related to urinary creatinine.
Kinetic studies of a quantitative single-tube enzyme-linked immunosorbent assay.
Authors: Tsang V C , Wilson B C , Maddison S E 
Published: January 2020

Abstract
We describe a single-cuvette enzyme-linked immunosorbent assay (ELISA) based on enzymic rate kinetics. This kinetic assay can yield linear quantitative data on immunoglobin concentrations. Optimum assay conditions, component concentrations, reaction intervals, and pH are described. Assay linearity and sensitivity are demonstrated in systems involving immunoglobulin G and antibodies to it, and with pooled sera from monkeys infected with Schistosoma mansoni.
Kinetic ethylene glycol assay with use of yeast alcohol dehydrogenase.
Authors: Eckfeldt J H , Light R T 
Published: January 2020

Abstract
We describe a rapid, accurate, and precise two-point kinetic assay for ethylene glycol. The method involves use of a standard kit for ethanol determination with yeast alcohol dehydrogenase, and of a centrifugal analyzer. Alcohol dehydrogenase catalyzes the oxidation of ethylene glycol in a trichloroacetic acid-precipitated specimen; the resulting NADH production is monitored at 340 nm. The reaction rate is linear with concentration to 1.5 g of ethylene glycol per liter. Interference from methanol, ethanol, and isopropanol was easily recognized after a 30-min incubation at 100 degrees C. We believe that the method can be readily adaptable to any narrow-bandwidth, stable, temperature-controlled spectrophotometer and so should provide more widely for the prompt assessment of patients in whom ethylene glycol poisoning is suspected.
Commercially available blood-gas quality controls compared with tonometered blood.
Authors: Leary E T , Graham G , Kenny M A 
Published: January 2020

Abstract
We compared three commercially supplied blood-gas quality control solutions ("contrIL," "G.A.S.," and "Quantra") and tonometered whole blood under research and service conditions in four hospital laboratories. In some situations Quantra and tonometered blood were comparably sensitive to problems with blood-gas instrument malfunctions (e.g., hydraulics or temperature control) but the aqueous buffer-based materials were less sensitive. Within-day precision for all control materials was similar. The precision of pCO2 determinations in long-term studies was also similar for all control materials, as were pH determinations on commercial controls. For pO2 (especially at O2 &lt; 50 mmHg), sample handling technique influenced the precision and accuracy of Quantra more than the other materials. The variability in pO2 determination with Quantra seems primarily to result from sensitivity in incubation temperature (3% change per degree C at 145 mmHg and 7% change per degree C at 43 mmHg). This study identifies some of the limitations of blood-gas control materials per se and some limitations related to specific blood-gas instruments that affect interpretation of results from them.
Reappraisal of the uroporphyrinogen I synthase assay, and a proposed modified method.
Authors: Chamberlain B R , Buttery J E 
Published: January 2020

Abstract
Problems encountered in the uroporphyrinogen I synthase assay were found to be due to the Triton reagent, slit-width and excitation wavelength settings of the spectrophotofluorometer, and leg-phase in the enzyme reaction. Of Triton X-100 from four suppliers, only three were found suitable. Differences in enzyme activity owing to slit-width adjustments were resolved by measuring the fluorescence of the sample (uroporphyrin) at 405 nm and the standard (coproporphyrin) at 401 nm. The lag-phase in the activated-enzyme assay is incorporated in the 30-min preincubation of the blood specimen in our modified method, thus giving higher enzyme activity than found with the original assay. The range for our method is 7.3--15.8 nmol s-1 L-1 (mean = 10.9; SD = 2.07).
Liquid-chromatographic measurement of urinary monosaccharides.
Authors: D'Amboise M , Hanai T , Noël D 
Published: January 2020

Abstract
We describe "high-performance" liquid chromatography of urinary monosaccharides on a macroporous anion-exchange resin (Hitachi 3013N), with acetonitrile/water as eluent. The separated xylose, arabinose, D-fructose, mannose, galactose, and D-glucose were detected by means of a post-column reduction reaction of tetrazolium blue. Absolute limits of detection were about 10 ng of monosaccharide. Lactose can also be measured.
Effect of in vitro hemolysis on assay of plasma catecholamines and DOPA.
Authors: Smith R T 
Published: January 2020

Abstract
I analyzed for free and sulfate-conjugated catecholamines and DOPA (3,4-dihydroxyphenylalanine) in four aliquots of a single plasma pool with use of Upjohn's "Cat-A-Kit" (catecholamines radioenzymatic assay kit [3H]. One aliquot was a clear plasma control; the others were supplemented with different concentrations of lysed human erythrocytes, to investigate possible interference by hemolysis with analysis for norepinephrine, epinephrine, dopamine, or DOPA in plasma. I observed no statistically significant difference that could be attributed to the degree of hemolysis between control and treatment groups for DOPA or any catecholamine fraction. Hemolysis in plasma from improper collection or processing techniques apparently does not preclude accurate and precise quantitation of free or sulfate-conjugated catecholamines or DOPA with the Cat-A-Kit.
Simplified method for detecting anti-insulin antibodies and insulin-anti-insulin immune complexes.
Authors: Virella G , Russell D , Laimins M , Colwell J 
Published: January 2020

Abstract
A simplified approach for estimating free and total anti-insulin antibodies and soluble insulin-anti-insulin immune complexes in serum has been developed and evaluated. For determination of free anti-insulin antibodies, a binding ratio for 125I-labeled insulin at fivefold serum dilution is calculated; the binding ratios obtained are reproducible (run-to-run coefficient of variation, 7.3%) and correlate well with titration of anti-insulin antibodies by other techniques (correlation coefficient, 0.9327). Total anti-insulin antibody concentrations are determined by calculating the [125I]insulin binding ratio for a sample previously acidified, adsorbed with acid dextran-coated charcoal, and neutralized. The difference in binding ratios between two aliquots of the same serum, one diluted 10-fold without manipulation and the second studied at an identical dilution after acidification and removal of free insulin, is taken as an index of the presence of soluble insulin-anti-insulin immune complexes. Because the tests can be performed at a single dilution, both time and materials are conserved without apparent loss of discrimination between sera with high antibody titers and high concentrations of insulin-anti-insulin immune complexes and sera with negative titers or low concentrations.
Detection of pentazocine and tripelennamine in urine.
Authors: Reid R W , Gerbeck C M 
Published: January 2020

Abstract
Pentazocine and tripelennamine can be identified in urine as a part of routine screening for drug abuse. Pentazocine, pentazocine hydrate, and tripelennamine can be detected by thin-layer chromatography of chloroform/isopropanol extracts of heat- and acid-hydrolyzed urine. Gas chromatography is used for confirmation. Gas chromatographic/mass spectrometric studies (chemical ionization mode) show that such extracts contain major molecular (M+) ions of m/e 256, 286, and 304, indicating the presence of tripelennamine, pentazocine, and pentazocine hydrate, respectively.
4-nitrophenyl phosphate--characterization of high-purity materials for measuring alkaline phosphatase activity in human serum.
Authors: Bowers G N , McComb R B , Upretti A 
Published: January 2020

Abstract
We studied 53 lots of 4-nitrophenyl phosphate (I), obtained from 20 different commercial suppliers, and used this information to set specifications for it. Using these well-defined specifications, we classified 21 lots of I as "unacceptable," 26 lots as "borderline," and six as "acceptable." All lots were shown to contain some 4-nitrophenol and inorganic phosphate. However, "acceptable" I had &lt; 0.3 mmol of 4-nitrophenol and &lt; 10 mmol of inorganic phosphate per mole of I. The mole concentration of I (based on disodium hexahydrate, formula weight 371) was determined by enzymic conversion to 4-nitrophenol in five lots of "acceptable" materials. The mole fraction of I ranged from 0.982 to 0.998. From these measurements and from estimates of impurities that absorb at 311 nm, as determined by liquid chromatography and spectrophotometry at other wavelengths, our best estimate of the molar absorptivity of I at 311 nm in 10 mmol/L NaOH at 25 degrees C was 9867 L x mol-1 x cm-1, with a total uncertainty of 76 L x mol-1 x cm-1. We recommend that I used in clinical laboratories for measurement of alkaline phosphatase activity in serum meet the specifications given in this paper: I content &gt; 98%, maximum activity &gt; 98% in comparative testing with other "acceptable" lots of I, and impurities not to exceed the values cited above.
Effect of outlying standard points on curve fitting in radioimmunoassay.
Authors: Hawker F J , Challand G S 
Published: January 2020

Abstract
Outlying points often appear in standard curves for radioimmunoassay. We have examined the effect of outlying standard points on the ability of various automated data-processing routines, and of manual operators, to position a radioimmunoassay standard curve correctly. Manual operators were found to be highly subjective in their handling of a standard curve containing outlying points. Automated methods without outlier rejection capability produced standard curves that were significantly erroneous. In contrast, a data-processing method with automated outlier rejection capability successfully identified outliers, but occasionally rejected valid points--and consequently misplaced the standard curve. Visual identification of outliers is unsatisfactory. Automated identification can be more satisfactory, but some patterns of outliers make it less so. We conclude that any automated data-processing method should contain an outlier rejection facility, but its results should be treated with caution.
Evaluation of a new valproic acid enzyme immunoassay and comparison with a capillary gas-chromatographic method.
Authors: Braun S L , Tausch A , Vogt W , Jacob K , Knedel M 
Published: January 2020

Abstract
A new homogeneous immunoassay (EMIT) for valproic acid was evaluated. Besides testing the manual version of this enzyme immunoassay, we also developed two mechanized procedures for centrifugal analyzers (the CentrifiChem and the COBAS system), which take less time and are more precise than the manual method. Within-assay precision (CV) was 4.5% with the manual technique and 2% with the analyzers. Between-assay precision (CV) ranged from 4 to 13% for all three techniques. Accuracy of th manual method was checked by dilution and analytical recovery experiments. Our comparison of the EMIT results with those obtained by a comparison method (capillary gas chromatography) showed no significant difference. No interference from hemolysis, hyperbilirubinemia, or aliphatic amino acids was observed. At high concentrations of bile acids and with lipemic sera the analytical recovery rates decreased slightly, to 87% and 92%, respectively.
Liquid chromatography at 3-methoxy-4-hydroxyphenylethylene glycol in urine with fluorescence detection.
Authors: Taylor J T , Freeman S , Brewer P 
Published: January 2020

Abstract
We describe a liquid-chromatographic procedure for determining low concentrations of 3-methoxy-4-hydroxyphenylethylene glycol in urine. After liquid-liquid extraction and cleanup of the sample, an aliquot of the extract is injected onto a reversed-phase chromatographic column, with isocratic elution with an acetonitrile/acetate buffer mobile phase. An on-line fluorescence detector is used for measuring the natural fluorescence of the compound. The method gives a relatively clean extract, which is suitable for measuring the less-than-normal concentrations associated with mentally depressed patients. Although a liquid-chromatographic technique has been recently described for measuring this compound in urine, the method involves electrochemical detection, which may not be available in many clinical laboratories, and, because of its nonspecificity, the method is only suitable for detecting the increased amounts of 3-methoxy-4-hydroxyphenylethylene glycol excreted by patients with pheochromocytoma.