bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of sample aging on total cholesterol values determined by the automated ferric chloride-sulfuric acid and Liebermann-Burchard procedures.
Authors: Wood P D , Bachorik P S , Albers J J , Stewart C C , Winn C , Lippel K 
Published: January 2020

Abstract
To investigate the comparability of three commonly used methods for determination of total cholesterol in plasma in several studies, we used fresh plasma samples as well as plasmas and reference sera that had been stored frozen at −15 degrees C for as long as several years. Duplicate determinations by the manual method of Abell et al. (J. Biol. Chem. 195: 357, 1952) were compared with estimates from one to five continuous-flow analyzers by the ferric chloride-sulfuric acid procedure and also with estimates from five to 13 continuous-flow analyzers by the Liebermann-Burchard procedure with calibrator, as part of the laboratory standardization activities of the Lipid Research Clinics. The agreement among all three procedures was generally within acceptable limits (within 5% of the manual method) when plasmas or sera were fresh or had been frozen for less than one month. Results by the manual method of Abell et al. agreed well with those by the automated Liebermann-Burchard method for samples that had been stored at −15 degrees C for as long as two years. However, the automated ferric chloride-sulfuric acid procedure often showed unacceptably high values (as compared with those from the manual method) for samples that had been stored frozen for a year or more. With the ferric chloride-sulfuric acid method, measured cholesterol concentration increased about 2.5% per year of storage for at least two years. We conclude that reference sera of plasmas that have been kept in long-term frozen storage (−15 degrees C) are not suitable for ongoing standardization of the automated ferric chloride-sulfuric acid assay for cholesterol.
Purification of an alkaline phosphatase-lipoprotein-X complex.
Authors: Weijers R N , Kruijswijk H , Baak J M 
Published: January 2020

Abstract
An alkaline phosphatase isoenzyme was observed in an abnormal position in the agar-agarose gel pattern of sera from several patients suffering from intrahepatic and extrahepatic cholestasis. We purified this isoenzyme, by gel filtration and affinity chromatography, from the serum of a patient suffering from extrahepatic cholestasis. Analysis demonstrated an alkaline phosphatase-lipoprotein-X complex with a relative molecular mass of at least 669,000. We discuss the interpretation of alkaline phosphatase isoenzyme patterns produced by different techniques.
Improved separation of creatine kinase isoenzymes by use of DEAE-Sepharose Cl-6B.
Authors: Bondar R J , Shevchik D G , Hsu M Y , Kohler M M 
Published: January 2020

Abstract
We describe here a simple, rapid chromatographic procedure for quantitatively separating serum creatine kinase isoenzymes (EC 2.7.3.2), with diethylaminoethyl (DEAE)-Sepharose CL-6B as the anion-exchanger. We established the column bed height and the elution parameters by use of a simplex procedure. DEAE-Sepharose CL-6B equilibrated in tris(hydroxymethyl)aminomethane (50 mmol/L, pH 7.5, and containing 30 mmol of NaCl per liter) is packed into a miniature polystyrene column with bed dimensions of 0.7 x 1.5 cm. The DEAE-Sepharose column system was evaluated and compared with a DEAE-Sephadex A-50 column system. The results indicate that the Sepharose column yields MM, MB, and BB isoenzymes uniquely, without cross contamination. Coefficients of variation (CV’s) for 10 replicate column assays were 2.8, 5.9, and 15.2% for 569 U of MM per liter, 82.3 U of MB per liter, and 9.0 U of BB per liter, respectively. The serum sample was enriched with baboon heart extract. Day-to-day reproducibility for a serum control assayed on 10 days yielded CV’s of 4.6, 9.9, and 40.3% for 391, 45.3 and 1.9 U of isoenzymes MM, MB, and BB per liter, respectively. A reference interval for each isoenzymes was derived from data on 81 men and 63 women.
Microencapsulated antibodies in radioimmunoassay. III. Determination of cortisol.
Authors: Bordens R W , Halpern E P 
Published: January 2020

Abstract
We describe a method for directly measuring total plasma cortisol by use of a microencapsulated antibody. The antibody microcapsules were incubated with plasma and 125I-labeled cortisol in a competitive reaction at 37 degrees C for 15 min, then separated by centrifugation; the radioactivity of the pellet was counted for 1 min. Analytical recovery of cortisol from three plasma pools was 97.6% (SD 8.5%) and was unaffected by triglyceridemia, hemolysis, or icterus. The standard curve was linear to 500 microgram/L and the sensitivity was 10 microgram/l. Recovery of cortisol added as the hemisuccinate was 102% (SD 10.6%), whereas that of the conjugate cortisol hemisuccinate/bovine serum albumin was 4.3% (SD 3.5%). This confirmed that the microcapsule excludes large molecules. The within-day CV for two control pools was 9.8 and 12.8%, the day-to-day variation 13.4 and 13.8%.
Lot-to-lot variation in three thyroid-related radioimmunoassay kits.
Authors: Zweig M H , Robertson E A 
Published: January 2020

Abstract
We examined lot-to-lot variation in triiodothyronine, thyroxine, and thyrotropin radioimmunoassay kits over 14–20 months. For the thyroxine assay, less than 20% of the overall variation was attributable to lot-to-lot changes. In contrast, for the triiodothyronine and thyrotropin assays half to two-thirds of the overall variation was attributable to lot-to-lot differences. The shifts seen in control results were also observed in results for patients. These shifts produced disturbing deviations on quality-control charts but did not appear to compromise the clinical utility of the results. We conclude that lot-to-lot variation can account for a major part of the long term variability of radioimmunoassay kit results and should be considered in evaluating kits and monitoring their performance.
Evaluation of standard curves in the graded hemagglutination-inhibition method applied to quantitation of human immunoglobulins.
Authors: Wolk M 
Published: January 2020

Abstract
For accurate quantitation of human immunoglobulins A and B by graded hemagglutination inhibition, I have established standard curves. For IgA, plotting the inner diameter of the ring formed by sedimented erythrocytes vs the log of the antigen concentrations gives a straight line. Plotting the same parameters for IgG gives a hyperbolic line. These ratios between antigen concentration and ring diameter were constant for at least one year. Both undiluted and 10,000-fold diluted human serum may be quantitated by this method, depending only on immunoglobulin concentrations. Precision (CV) of the system, assessed in 35 patients’ sera over the period of one year, ranged from 0.5 to 15.2% (mean 10%) for IgA and from 1.4 to 14.9% (mean 7.3%) for IgG.
Bilirubin binding capacity of albumin isolated from cord-blood serum is less than that from serum of adults.
Authors: Alayoff A , Kapitulnik J , Konijn A , Kaufmann N A , Blondheim S H 
Published: January 2020

Abstract
As estimated by Sephadex gel filtration, the bilirubin binding capacity of albumin isolated from cord-blood serum by ion-exchange chromatography is less than that of albumin isolated from serum of adults. Albumin isolated from cord-blood serum showed increased bilirubin binding as compared with the albumin in the native serum. These findings suggest that the lower bilirubin binding capacity of serum from newborns as compared with serum from adults is a result of both an intrinsic deficiency in binding capacity of neonatal albumin and the presence of substances in neonatal serum that interfere with bilirubin binding.
Problems in radioimmunoassay of human lutropin with commercially available reagents.
Authors: Hammond J E , Phillips J C , Straight C B , Hammond M G 
Published: January 2020

Abstract
To evaluate five commercially available reagent sets supplied for the radioimmunoassay of lutropin, we determined whether there was parallelism between the curve given by dilutions of the standards supplied by the manufacturers, by dilutions of a serum pool, and by dilutions of a standard preparation from human pituitaries, LER-907. These studies demonstrated significant analytical problems with three of the five sets. We conclude that each user should carefully evaluate all commercially available radioimmunoassays for lutropin (and, by inference, for other peptide hormones) before use.
Decreasing sample volume used in the “Sequential Multichannel Analyzer Computerized” (SMAC).
Authors: Stamper R , Robertshaw D M 
Published: January 2020

Abstract
We describe modifications to two cartridges, those for alkaline phosphatase and creatinine, on an 18-channel SMAC (Sequential Multichannel Analyzer Computerized), which allow all 18 tests to be run with a commonly prediluted sample. This decreases the required sample size and eliminates the problem of fibrin clots in the stream-splitter on the main sample line. The modifications can be made rapidly and require few new components. Accuracy, precision, linearity, and carryover are acceptable after these modifications, as judged by comparison with premodification data. Some financial savings ensue from the decreased consumption of reagents and the fewer repeat analyses necessitated by clotting problems.
Total serum cholesterol by isotope dilution/mass spectrometry: a candidate definitive method.
Authors: Cohen A , Hertz H S , Mandel J , Paule R C , Schaffer R , Sniegoski L T , Sun T , Welch M J , White E 
Published: January 2020

Abstract
We describe a highly accurate and precise method for determination of total cholesterol in serum by isotope dilution/mass spectrometry. The method was developed for a Study Group of the Committee on Standards of the American Association for Clinical Chemistry, for use in establishing the accuracy of a candidate reference method for total cholesterol, and fulfills their criteria for a definitive method. Cholesterol-d7 is added to serum, with the weight ratio of cholesterol-d7 to total serum cholesterol kept near to 1:1. The esters are hydrolyzed and the cholesterol is separated and converted into the trimethylsilyl ether derivative for measurement by combined gas chromatography/mass spectrometry. The intensity ratio of the molecular ions at m/z 465 and 458 is measured for each sample and for two calibration mixtures, according to a prescribed bracketing protocol. A weight ratio for the sample is obtained by linear interpolation of the ion-intensity ratios, and the total cholesterol is then calculated. The method was applied four times over several weeks to each of five serum pools. Statistical analysis involving consideration of both replication error and variability between weeks gave a coefficient of variation for a single measurement of 0.36%. The absence of interferences in the method was demonstrated by measurements at several other masses.
Liquid-chromatographic separation of urinary 5-hydroxy-3-indoleacetic acid, with measurement at 254 nm.
Authors: Draganac P S , Steindel S J , Trawick W G 
Published: January 2020

Abstract
A "high-performance" liquid-chromatographic procedure for 5-hydroxy-3-indoleacetic acid is described and compared with a colorimetric method in which 1-nitroso-2-naphthol is used. The analyte and an internal standard, p-nitrobenzoic acid, were extracted into diethyl ether from urine at pH 4.0 (acidified with HCl) to which sodium chloride had been added, and the ether was back-extracted with acetate buffer, pH 9.2. Aliquots of this extract were injected into a reversed-phase liquid-chromatographic column and eluted with pH 3.5 acetate buffer/methanol (95/5 by vol); the effluent was monitored at 254 nm. The precision (CV) of the method was 11.8% at 1.8 mg/L, 5.5% at 92 mg/L. Analytical recovery averaged 84%. The colorimetric method gave higher values for the analyte than did the chromatographic method for all patients' urines.
Use of soluble and Staphylococcus aureus-immobilized second antibody compared in a radioimmunoassay for human alpha-fetoprotein.
Authors: Ruch F E , Knight G J 
Published: January 2020

Abstract
Staphylococcus aureus cells coated with rabbit anti-goat immunoglobulin G were compared with soluble second antibody in a radioimmunoassay for human serum alphafetoprotein. Recovery of primary immune complexes with use of the bacterial immunoadsorbant (a) allowed second-antibody incubation time to be shortened from 3 h to 20 min at 37 degrees C, (b) decreased by 80% the amount of second antibody required per assay, thereby significantly reducing assay costs, and (c) provided a convenient and reproducible method for separation of free and bound antigen. The ease of preparation and the uniformity and stability of the S. aureus second-antibody reagent are additional advantages that may be useful in other radioimmunoassay procedures.
Radioimmunoassay of free thyroxine in serum: comparison with clinical findings and results of conventional thyroid-function tests.
Authors: Bayer M F , McDougall I R 
Published: January 2020

Abstract
We have evaluated a radioimmunoassay for free thyroxine (FT4) involving antibody-coated tubes (GammaCoat 125I Free T4RIA; Clinical Assays, Div. of Travenol Labs, Inc.). The coefficient of correlation between FT4 and the FT4 index was 0.98 for all patients with various thyroid disorders, 0.77 for hospitalized patients with miscellaneous diseases, and 0.74 for healthy individuals. FT4 values also agreed well with triiodothyronine or thyrotropin concentrations in these patients and were consistent with each patient's clinical status. Patients with severe nonthyroidal illnesses and abnormal thyroid-function tests, despite clinical euthyroidism, had normal FT4 values. In this group, the mean FT4 was almost identical to that in the controls, although mean thyroxine, triiodothyronine, and FT4 index differed significantly and the correlation between FT4 and FT4 index was poorer (r = 0.66). For most patients, the diagnostic value of FT4 measurements is comparable to that of the FT4 index, and it may be superior in patients with severe nonthyroidal illnesses. The test costs less and saves time as compared to the FT4 index computation, and it can be used routinely with thyrotropin assay for the diagnosis of hypothyroidism or with triiodothyronine assay for the diagnosis of hyperthyroidism.
Fluorometric micromethod for determination of arginase activity in dried blood spots on filter paper.
Authors: Orfanos A P , Naylor E W , Guthrie R 
Published: January 2020

Abstract
We describe a microfluorometric method for determination of arginase activity in dried blood spots on filter paper. The arginase in discs punched from such dried blood specimens is activated by preincubation with Mn2+ at 37 degrees C. After incubation with substrate at the same temperature, urea is determined fluorometrically by oxidation of NADH to NAD+ in a coupled kinetic reaction. We compare the results of this method with those of a colorimetric method involving liquid blood samples, and assess the stability of the enzyme in dried blood on filter paper. The presence of serum has no effect on the activity. This method may be useful in the early detection of arginase deficiency and certain hematological disorders.
Further experience with computer-assisted diagnosis of diseases of the liver and biliary tree.
Authors: Ellis G , Worthy E , Goldberg D M 
Published: January 2020

Abstract
Computer-assisted classification of disease has largely relied upon testing the diagnostic algorithm in the same population from which it was originally derived, as a means of validation. To evaluate the accuracy of a diagnostic program in which discriminant function analysis is used, we applied it to a separate population, selected by different criteria from those used to define the original case material on which the diagnostic program was based. We selected a group of 315 patients having abnormal values for alkaline phosphatase, bilirubin, or aspartate aminotransferase for further biochemical and immunological investigations. We used a computer program involving discriminant function analysis and classification procedures primed with the results of 10 tests obtained on each of 535 patients in a previous series to allocate those 173 new patients who had diseases of the liver or biliary tree into one of 13 disease groups. The classification was less accurate than was the case in previous cross-validation studies. We developed new discriminants with the new case material, using the same group of tests, and when cross-validation was performed, overall accuracy was greatly improved. These experiences point to the powerful influence of group selection upon computer-assisted diagnostic procedures, and the hazards of applying to one clinical population discriminant functions derived from a different population.
Determination of high-density lipoprotein phospholipids in serum.
Authors: Yamaguchi Y 
Published: January 2020

Abstract
I describe a method for measuring high-density lipoprotein phospholipids. Magnesium chloride and dextran sulfate are used to precipitate all low-density and very-low-density lipoproteins. The supernate contains only high-density lipoproteins, the phospholipid concentration of which is determined by an enzymic method. The precision of the method (CV) is 2.35% (10 repeated assays), and the mean value for HDL-phospholipids was 1006 (SD 248) mg/L for 30 apparently healthy subjects. I used electrophoresis and enzymic color development to confirm the presence of HDL-phospholipids. Results are compared with those obtained by an ultracentrifugation method.
Two-dimensional gel electrophoresis of cerebrospinal fluid proteins.
Authors: Goldman D , Merril C R , Ebert M H 
Published: January 2020

Abstract
Two-dimensional electrophoresis, with isoelectric focusing in the first dimension and sodium dodecyl sulfate/polyacrylamide gel electrophoresis in the second, has been adapted for the high-resolution analysis of cerebrospinal fluid proteins. Proteins were detected with a new, highly sensitive silver stain that made visible more than 300 polypeptides from 60 microL of spinal fluid, in highly reproducible patterns. We have mapped these patterns, noting difference between the proteins observed in spinal fluid and plasma, and have prepared a partial map of cerebrospinal fluid proteins.
Increased activity in serum of an alkaline phosphatase isoenzyme in cancer: analytical method and preliminary clinical studies.
Authors: Kahan L , Go V L , Larson F C 
Published: January 2020

Abstract
Serum of cancer patients often contains high activities of a homoarginine-sensitive isoenzyme of alkaline phosphatase with high electrophoretic mobility, which is present in relatively low activities in sera from most normal persons and persons with benign disease. In earlier studies of this isoenzyme, in a semi-quantitative assay, electrophoresis was used in the separation step. This report describes a column separation procedure, which provides quantitative data. We tested the revised procedure by assaying a mixed panel of 192 sera (cancer, benign disease, and normal). The organ sites of cancer and benign disease in this study were: lung, pancreas, uterus, and ovaries. The isoenzyme showed moderate sensitivity for lung (0.6) and pancreas (0.8) cancer and high specificity for all cancers tested. Thus the assay may be useful for discriminating between cancer sera and non-cancer sera for these cancer types.
A single liquid-chromatographic procedure for therapeutic monitoring of theophylline, acetaminophen, or ethosuximide.
Authors: Quattrone A J , Putnam R S 
Published: January 2020

Abstract
Simultaneous and semi-automated determinations of theophylline, acetaminophen, and ethosuximide from human serum are possible through use of a programmable autoinjector, an isocratic mobile phase, and reversed-phase "high-performance" liquid chromatography on a muBondapak C18 column. To avoid salt damage to the valves and the fittings of the autoinjector and solvent pump, we used only volatile, ion-pairing buffers such as triethylamine/acetic acid or N-ethylmorpholine/acetic acid at apparent pH 4.8 in acetonitrile/water (1/11 by vol). With this method we can separate theophylline, acetaminophen, and ethosuximide from 26 other drugs, metabolites, and related substances. Results by this procedure and the EMIT procedure for theophylline and ethosuximide in patient and control sera correlated well (r = 0.944 and 0.968, respectively). We conclude that this single chromatographic system reliably and economically yields analysis of three widely used therapeutic drugs on a routine or emergency basis.
Evaluation of free and total L-thyroxine in serum by a commercial procedure.
Authors: Obregon M J , Kurtz A , Ekins R , Morreale de Escobar G 
Published: January 2020

Abstract
We assessed a commercial kit (Corning Medical) for "free" and total thyroxine determination, results being compared to those obtained by the Ekins and Ellis dialysis method (free thyroxine) and the method of Weeke and Orskov (total thyroxine). The kit procedure permits determination of both free and total thyroxine within 4 to 5 h, and the combined results may disclose changes in binding to plasma proteins that would be missed if only free thyroxine were determined. With both free-thyroxine methods, the values distinguished hyperthyroid patients from normal controls and pregnant women with 100% accuracy, but there was some overlap between hypothyroid patients and controls. Absolute values with the kit procedure often exceed those obtained by dialysis, especially for hypothyroid patients and pregnant women. We conclude that the kit may be of as much diagnostic value as the dialysis method if the limitations regarding absolute values are kept in mind and the test is not used as a substitute for thyrotropin determinations in cases of suspected hypothyroidism.
Diagnosis of self-induced hyperinsulinism in an insulin-dependent diabetic patient by radioimmunoassay of free C-peptide.
Authors: Meistas M T , Kumar M S , Schumacher O P 
Published: January 2020

Abstract
On the basis of results of simultaneous determinations of plasma free insulin and free c-peptide, episodes of hypoglycemia in an insulin-dependent diabetic were attributed to surreptitious self-administration of insulin. Immunoreactive c-peptide values were falsely increased and diagnostically misleading when measured in unextracted plasma. After preliminary removal of antigen/antibody complexes from the plasma by extraction with polyethylene glycol, the c-peptide values, referred to as "free c-peptide," were suppressed. We suggest that insulin antibodies formed complexes with proinsulin-like material in the plasma of this patient, which accounted for most of the c-peptide immunoreactivity in her unextracted plasma. These complexes must be removed if c-peptide measurements are to be accurate.