bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of two assays of functional surfactant in amniotic fluid: surface-tension lowering ability and the foam stability index test.
Authors: Statland B E , Freer D E 
Published: January 2020

Abstract
We characterize two assays of total amniotic fluid surfactant that are based on function: the surface-tension lowering ability of extracts of amniotic fluid lipid (I) and the foam stability index test (II). I is determined on chloroform extracts of amniotic fluid. II is defined as the highest ethanol volume fraction of an amniotic fluid-ethanol mixture that will permit a stable foam to form after 30 s of vigorous shaking. The relationship of I to disaturated phosphatidylcholine concentrations (after osmium tetroxide treatment of the amniotic fluid lipid extract) is in the expected theoretical form of a hyperbolic function. The relation between values for II and disaturated phosphatidylcholine concentrations showed a consistent bias, suggesting that components other than disaturated phosphatidylcholine contribute to stable foam formation. Phosphatidylclycerol concentrations did not appear to account for this bias. The relation between I to II values suggest that both assays measure total surfactant. I, II, and concentration of disaturated phosphatidyl choline are all excellent indicators of fetal pulmonary maturity. From a practical standpoint, the foam stability index test is the most efficient approach to routine assessment of fetal pulmonary status.
Comparison of two micromethods for determination of lipoprotein cholesterol in plasma.
Authors: Kupke I R , Zeugner S , Gottschalk A 
Published: January 2020

Abstract
We compared the results obtained by a micromethod for the determination of plasma lipoprotein cholesterol, in which electrophoresis is used to separate the lipoprotein fractions (beta-, pre-beta-, and alpha-lipoproteins), with those determinations with ultracentrifugation (low-density, very-low-density, and high-density lipoproteins). Precision of determination (coefficient of variation, CV, %) was the same for beta- and low-density lipoproteins (1.6%), and for pre-beta- and very-low-density lipoproteins (3.7%); however, determination of alpha-lipoprotein cholesterol was more precise (1.4%) than that of high-density lipoprotein cholesterol (3.1%). Analytical recovery of lipoprotein cholesterol was the same for both methods (98--100%) and the results were closely correlated (r = 0.943). The procedure has been used to determine the cholesterol content of plasma lipoprotein fractions of apparently healthy adults (both sexes). Lipoprotein cholesterol concentrations in our population sample compare well with those reported for other groups of similar age, in particular Stanford long-distance runners.
Evaluation of the DuPont aca amylase method.
Authors: Balkcom R M , O'Donnell C M , Amano E 
Published: January 2020

Abstract
The dilution/activity curve for the DuPont aca kinetic amylase (EC 3.2.1.1) method is linear to approximately six times the upper limit of the expected range. Total reaction time on the aca is 4.3 min; however, there is a nonlinear rate of change in absorbance for at least the first 8 min, which is consistent with a lag phase. The within-run and day-to-day coefficients of variation were 2.4% at 100 U/L and 3.6% at 114 U/L, respectively. There was no interference by marked hemolysis (hemoglobin 4 g/L) or by glucose concentrations of 10--50 g/L. Comparisons by the split-sample method between the Amylochrome procedure and the aca procedure gave correlation coefficients of 0.992 for serum and 0.989 for urine. A second comparison, between the AutoAnalyzer I method and the aca, gave correlation coefficients of 0.998 for serum and 0.909 for urine. The expected range for serum was 18--106 U/L and for urine 2--33 U/2 h.
Evaluation of the BMC glucose oxidase/peroxidase-4-aminophenazone-phenol procedure for glucose as adapted to the Technicon SMAC.
Authors: Purcell G V , Behenna D B , Walsh P R 
Published: January 2020

Abstract
We evaluated the analytical performance of Trinder's glucose oxidase (EC 1.1.3.4)/peroxidase (EC 1.11.1.7) 4-aminophenazone-phenol method for the quantification of serum glucose as adapted to the Technicon SMAC. Our results correlated well with those by the routine SMAC glucose oxidase/peroxidase 3-methyl-2-benzothiazolinone hydrazone-N,N-dimethylaniline method (y = 1.02x - 49.4; r = 0.99) and the glucose oxidase oxygen-rate method (y = 0.99x + 14; r = 0.99) with the Beckman Glucose Analyzer. Sample-to-sample interaction was less than 1%. Ascorbic acid or uric acid in concentrations as high as 200 mg/L were without demonstrable effect on results for glucose. Intra- and inter-assay precisions (CV) were 1.6 and 2.3%, respectively. The upper limit of linearity was about 5 g/L. Adaptation of the Trinder method for glucose to the SMAC is simple and provides an analytically acceptable and economical alternative to the methods ordinarily used with the SMAC.
Improvements in and clinical utility of a continuous-flow method for routine measurement of dialyzable (ultrafiltrable) calcium.
Authors: Toffaletti J , Bowers G N 
Published: January 2020

Abstract
We describe modifications to the original continuous-flow procedure for dialyzable calcium (Clin. Chem. 23: 1258, 1977) needed to make the method more suitable for routine clinical laboratory use. The modifications simplify the continuous-flow (AutoAnalyzer) manifold, decrease baseline noise, increase the sensitivity, and permit use of a less-expensive fluorometer. Bias due to variation in serum processing is minimized by use of serum samples minimally exposed to air and a pH 7.40 buffer in place of the routinely processed sera and pH 7.30 buffer used formerly. Day-to-day precision (CV) during the past year for samples that included three different lots of quality-control sera was 2 to 3%. The analysis requires 200 micro L of serum, collected with minor additional precautions. We find that dialyzable calcium can be dependably measured in the routine service laboratory and show how this information is clinically more useful than is information on total calcium in serum.
Liquid-chromatographic measurement of endogenous and exogenous glucocorticoids in plasma.
Authors: Frey F J , Frey B M , Benet L Z 
Published: January 2020

Abstract
The therapeutic response to and side effects of glucocorticoids will be better recognized and the recovery of the adrenals during the tapering of therapy with steroids better evaluated if endogenous and exogenous glucocorticoids are separately assessed. We describe a specific method for simultaneously measuring the concentrations of cortisone, cortisol, prednisone, and prednisolone in plasma by "high-pressure" liquid chromatography. The steroids, together with an internal standard, dexamethasone, are extracted from 1 mL of plasma with methylene chloride-ether, washed with acid and base, and separated isocratically on a normal-phase silica column with a mobile phase consisting of methylene chloride/tetrahydrofuran/methanol/glacial acetic acid (96.85/1/2.1/0.05 by vol) at a flow rate of 1.3 mL/min. The steroids are detected at 254 nm and quantitated by peak-height measurements; their retention times range from 6 to 20 min. The lower limits for routine detection of all four compounds is 10 microgram/L. The analytical recoveries are about 75%; the intra-day variability (CV) is 1 to 9%, and the inter-day variability 2 to 11%. Of 26 drugs and 20 steroids tested, only theophylline presents an interference problem.
Direct determination of lead and cadmium in blood and urine by flameless atomic absorption spectrophotometry.
Authors: Lagesson V , Andrasko L 
Published: January 2020

Abstract
We describe procedures for direct determination of lead and cadmium in blood and urine by flameless atomic absorption spectrophotometry. Before analysis, the samples are pre-ashed in microboats in an ordinary laboratory oven. In this way, many samples can be prepared and pre-ashed simultaneously. We find the procedures presented in this work to be rapid, accurate, and precise.
Pre-renal azotemia mimicking chronic renal failure in a hypotensive patient.
Authors: Darm J R , Bhagavan N V , Scottolini A G 
Published: January 2020

Abstract
A 56-year-old Samoan man with a documented history of hypertension, who presented with atrial fibrillation and hypotension, quickly developed renal failure with a serum urea nitrogen of 1.370 g/L and a serum creatinine of 92 mg/L. After hydration of the patient, the creatinine value became normal in two days, the urea nitrogen in four days. The urinary creatinine output during the first 24 h of hospitalization was 3.7 g. This case illustrates the rapidity with which unusually large amounts of creatinine (more commonly seen in chronic renal failure) can accumulate and be excreted in pre-renal failure. It also reaffirms the usefulness of the urea nitrogen/creatnine ratio in evaluating the causes of azotemia.
Creatine kinase measurement in the 1977 CAP Enzymology Survey: anomalies explained.
Authors: Handschuh G J , Donovan K L 
Published: January 2020

Abstract
In the recently published results of the 1977 College of American Pathologists Enzymology Survey, Some anomalous results were obtained in measuring the creatine kinase (EC 2.7.3.2) activity of the samples. The cause of these anomalies was discovered to be an arginine kinase (EC 2.7.3.3) contaminant in one of the enzyme pools used to make the samples. The contaminant shows cross reactivity with creatine phosphate and is activated by dithioerythritol but not the other commonly used thiol activators.
A new assay for diaphorase activity in reagent formulations, based on the reduction of thiazolyl blue.
Authors: Boethling R S , Weaver T L 
Published: January 2020

Abstract
This new assay procedure for diaphorase eliminates problems of high blank rates and nonlinear kinetics associated with other methods. The dye thiazolyl blue tetrazolium bromide is reduced in the presence of NADH and diaphorase to yield a colored formazan, which as maximum absorbance at 560 nm.
Assay of urinary 4-hdyroxy-3-methoxymandelic (vanillylmandelic) acid by liquid chromatography with electrochemical detection.
Authors: Morrisey J L , Shihabi Z K 
Published: January 2020

Abstract
We describe a method for the assay of urinary 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid) based on separation on a microparticulate reversed-phase column and direct electrochemical detection. The method can be used after extraction from urine or by direct urine injection after 100-fold dilution.
Thin-layer agarose electrophoresis of lactate dehydrogenase isoenzymes in serum: a note on the method of reporting and on the lactate dehydrogenase isoenzyme-1/isoenzyme-2 ratio in acute myocardial infarction.
Authors: Leung F Y , Henderson A R 
Published: January 2020

Abstract
We assessed the clinical efficacy of a thin-layer agarose electrophoresis assay for lactate dehydrogenase isoenzyme estimation in the diagnosis of acute myocardial infarction. From a population of 228 patients admitted to the Coronary Care Unit with suspected acute myocardial infarction, all 101 positive cases (confirmed by clinical presentation and electrocardiographic changes) were correctly identified with lactate dehydrogenase isoenzyme-1 percentage of total activity above the reference range and with a lactate dehydrogenase isoenzyme-1/isoenzyme-2 ratio of 0.76 or above. This ratio was between 0.45 and 0.74 for 250 healthy subjects. No falsely negative, but 12 falsely positive results were obtained from this Coronary Care Unit population, to give a sensitivity of 100% and a specificity of 90.5% for the ratio test.
New saccharogenic determination of alpha-amylase in serum and urine.
Authors: van Leeuwen L 
Published: January 2020

Abstract
I describe a new kinetic enzymatic saccharogenic method for assaying alpha-amylase in human serum and urine. alpha-Amylase liberates maltose from starch. This is successively acted on by alpha-glucosidase, mutarotase, and glucose dehydrogenase. The resulting conversion of NAD+ to NADH, measured at 340 nm, during a 20-min incubation reflects amylase activity. Endogenous glucose is destroyed before measurement of amylase activity is begun.
Enzyme-linked immunosorbent choriomammotropin assay.
Authors: Dittmar D , Monji N , Cid A , Malkus H , Castro A 
Published: January 2020

Abstract
We have devloped an enzyme-linked immunosorbent assay for determining choriomammotropin (human placental lactogen) in serum. Unlabeled hormone competes with choriomammotropin-beta-galactosidase conjugate for antibody bound to polystyrene tubes. The entire assay can be performed in 2.5 h with good precision. The coefficient of variation for one sample with a mean concentration of 5.6 mg/L, assayed 10 times on the same day, was 5.7%. The coefficient of variation for nine samples (3.5 to 9.0 mg/L) assayed on five different days was 7.9%. Forty-eight clinical samples were assayed (y) and compared with results obtained by radial immunodiffusion (x). The resulting regression equation was: y = 1.05x + 0.78; r = 0.91.
Electron-capture gas-liquid chromatographic determination of ethosuximide and desmethylmethsuximide in plasma or serum.
Authors: Wallace J E , Schwertner H A , Hamilton H E , Shimek E L 
Published: January 2020

Abstract
We describe the determination of ethosuximide and desmethylmethsuximide, simultaneously or separately, in 50 to 100 microliter of plasma or serum. Derivatives of ethosuximide and desmethylmethsuximide formed by reaction with pentafluorobenzoyl chloride are extremely sensitive to the electron-capture detector of a gas-liquid chromatograph. The sample, with added internal standard and ammonium sulfate as a pH-adjusting and salting-out agent, is extracted with ethyl acetate/benzene (20/80 by vol). The extract is evaporated and the derivatives are formed. Analytical recoveries of ethosuximide and desmethylmethsuximide exceed 99%, and the relative standard deviation (CV) between analyses is usually less than 4.0%. alpha-Methyl-alpha-propylsuccinimide is used as the internal standard for ethosuximide, 2-phenylsuccinimide as the internal standard for desmethylmethsuximide.
Analysis for urinary catecholamines by liquid chromatography with amperometric detection: methodology and clinical interpretation of results.
Authors: Moyer T P , Jiang N S , Tyce G M , Sheps S G 
Published: January 2020

Abstract
A method is presented for the quantitative analysis of urinary unconjugated norepinephrine, epinephrine, and dopamine as discrete entities. The procedure requires initial purification of the specimen on aluminum oxide and a boric acid-gel. We used "high-performance" reversed-phase paired-ion chromatography, with a flow-through amperometric cell as the detector. The CV was 6% for determination of norepinephrine, 11% for epinephrine, and 6% for dopamine monitored at physiologic concentrations of these compounds in urine. In a population study, urine specimens from 117 normal pediatric and adult subjects, 85 hypertensive patients, and 22 patients with surgically proved pheochromocytoma were analyzed. The specificity of the method for detection of pheochromocytoma was 100%, with a sensitivity of 97%.
Gel isoelectric focusing method for specific diagnosis of familial hyperlipoproteinemia type 3.
Authors: Warnick G R , Mayfield C , Albers J J , Hazzard W R 
Published: January 2020

Abstract
We describe a gel isoelectric focusing procedure for resolving into at least five bands the arginine-rich protein of very-low-density lipoproteins, and use the method in diagnosis of hyperlipoproteinemia type 3. We find that deficiency of one band, designated E3, relative to E2, expressed as an E3/E2 ratio less than or equal to 0.3, is specifically associated with hyperlipoproteinemia type 3 as diagnosed by traditional criteria in a large family study. In addition, we used the procedure to test 47 referral samples with demonstrable beta-migrating very-low-density liproprotein grouped by very-low-density lipoprotein cholesterol/total triglyceride ratios of greater than or equal to 0.3, from 0.25 to 0.3, and less than 0.25. All 24 of the first group, three of six in the second, and only one of 17 in the third had E3/E2 ratios of less than or equal to 0.3. Also, two normolipidemic children, without detectable lipoprotein abnormalities but related to subjects with hyperlipoproteinemia type 3, had E3/E2 ratios of less than or equal to 0.3. Use of our procedure improves the specificity of diagnosis and allows sensitive detection of asymptomatic subjects who may be at risk of developing the disorder.
Single- and coupled-enzyme nylon tube reactors for routine determination of pyruvate and lactate in serum.
Authors: Sundaram P V , Hinsch W 
Published: January 2020

Abstract
We describe the use of a continuous-flow clinical analyzer with an immobilized coupled-enzyme nylon tube reactor and an immobilized single-enzyme nylon tube reactor for routine estimation of lactate and pyruvate in serum. These reactors are incorporated into the flow system of a modified continuous-flow analyzer (Technicon AutoAnalyzer). Results for serum lactate and pyruvate by this method are compared with those by corresponding methods in which the same enzymes are used in solution, either automatically (pyruvate) or manually (lactate) performed. Routine clinical laboratory determinations with use of the coupled-enzyme system lactate dehydrogenase and alanine aminotransferase, co-immobilized in the nylon tube reactor for estimation of lactate, and lactate dehydrogenase reactors for estimation of pyruvate give reliable and reproducible results with high precision at low cost.
Enzyme immunoassay of carbamazepine with a centrifugal analyzer.
Authors: Lacher D A , Valdes R , Savory J 
Published: January 2020

Abstract
We describe a rapid enzyme immunoassay for carbamazepine with a centrifugal analyzer (Rotochem IIA-36). Reagent costs are reduced fourfold while good precision and sensitivity are maintained. Sample volume is 10 microliter, and as many as 28 patients' sera can be measured during an assay time of 225 s. Assay temperature is 30 degrees C, the wavelength 340 nn. Linearity is excellent for a carbamazepine concentration range of 1 to 12 mg/L; analytical recovery is quantitative. Results correlate well with those by liquid- and gas-liquid chromatography. Absorbance rates for each carbamazepine concentration are acquired by a multi-point kinetic rate program and a computer program provides a logit-log transformation of absorbance rate vs. concentration data for final calculations in the assay. Hemoglobin interference precludes analysis of severely hemolyzed specimens.
Phthalate interference in gas-chromatographic determination of long-chain fatty acids in plasma.
Authors: Geisler C , Swanson A R , Zieve L , Anders M W 
Published: January 2020

Abstract
Phthalates leached from plastic tubing or other plastic devices may interfere with gas-chromatographic determination of long-chain fatty acids in plasma. In the case of hospitalized patients who have received infusions or had blood drawn through plastic tubing, gas chromatography/mass spectrometry may be required for accurate determination of such fatty acids.
Improved indirect and direct radioimmunoassay for carcinoembryonic antigen.
Authors: Kumar M S , Carl K J , Deodhar S D 
Published: January 2020

Abstract
Values obtained by the indirect and the direct assays for carcinoembryonic antigen by use of the "CEA Roche" method and reagents differ significantly. In 32 samples the latter method gave values almost twofold those obtained by the former. The mean ratio for direct/indirect was 1.9 +/- 0.6. Analytical recovery experiments on samples to which known amounts of the antigen had been added showed a similar disparity. A simple modification of these two procedures, involving addition of normal human plasma (containing less than 2.0 microgram of the antigen per liter) to standards, eliminated this discrepancy. In the indirect method, standards were added to normal human plasma, then extracted with perchloric acid before assay. In the direct assay normal human plasma instead of goat serum, was added to standards. With these modifications the analytical recoveries of added CEA by the indirect and direct methods were 87 +/- 17% and 99.7 +/- 8%, respectively, and the mean ratio between two methods was 1.2 +/- 0.4.
Effect of protein on titrimetry of bicarbonate, titratable acid, and ammonium in urine.
Authors: Litkowski L J , Wilson T L 
Published: January 2020

Abstract
Measurement of bicarbonate, titratable acid (HTA+) and ammonium in the urine can facilitate clinical evaluation of acid-base status. Sequential measurement of these three components by titrimetric techniques is well established, but possible interference by proteinuria has not been examined. We report the influence on these analyses of albumin and globulin, two proteins commonly observed in urine in renal disease states. The presence of these proteins in urine affects the measurement of NH4+, and to a less extent that of HTA+. The magnitude of the effect depends on the concentration and the kind of protein present. Proteins do not influence the measurement of HCO3-.
Antibodies to native DNA: detection by immunoperoxidase assay and determination of their immunoglobulin classes.
Authors: Vladutiu A O , Palumbo D A , Asirwatham J E 
Published: January 2020

Abstract
Antinuclear antibodies are almost always found in sera of patients with systemic lupus erythematosus. To differentiate antinuclear antibodies from antibodies to DNA in the recently described Crithidia luciliae assay, we developed an immunoperoxidase technique for detecting antibodies to native, double-stranded DNA and compared results by it with those by the Farr assay. Smears of cultured Crithidia luciliae were incubated with human sera, peroxidase-labeled anti-human IgG serum, and diaminobenzidine. The peroxidase stain was examined by conventional light microscopy, which facilitated differentiation between the kinetoplast and the nuclear staining. The Crithidia assay appeared to be specific for double-stranded DNA antibodies, seemed to be more sensitive than the Farr assay, and allowed us to determine the immunoglobulin classes of antibodies to native DNA. Some patients with systemic lupus erythematosus had only IgM or IgA antibodies to DNA.
Secondary hypertriglyceridemia and hyperlipoproteinemia in patients with primary asymptomatic gout.
Authors: Naito H K , Mackenzie A H 
Published: January 2020

Abstract
We carefully selected 30 men with primary gout, rendered asymptomatic by therapy, to examine the frequency and type of hyperlipidemia and hyperlipoproteinemia, with the objective of determining whether serum uric acid, alcohol intake, liver function, kidney function, and (or) drugs were participating in the secondary lipid disorder. Sixty-one age- and sex-matched men were used as controls. About 73% of the gout patients had hypertriglyceridemia, 1.6-fold the frequency found in the control group. Types IV and IIb lipoprotein electrophoretic patterns were most prevalent in the gout group. Neither alcohol intake nor hyperuricemia, per se, seems to be the cause of the lipid and lipoprotein disorder and cannot be related to liver or kidney dysfunctions. Obesity was the major underlying factor associated with the lipidemia. The study suggests that diet and, possibly, defective clearance of triglycerides may be etiologic factors associated with the abnormal serum triacylglycerol (triglyceride) and lipoprotein concentrations in these individuals.