bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accuracy of some routine method used in clinical chemistry as judged by isotope dilution-mass spectrometry.
Authors: Björkhem I , Bergman A , Falk O , Kallner A , Lantto O , Svensson L , Akerlöf E , Blomstrand R 
Published: January 2020

Abstract
Serum from patients was pooled, filtered, dispensed, and frozen. This pooled specimen was used for accuracy control in 64 participating laboratories in Sweden. Mean values ("state-of-the-art" values) were obtained for creatinine, cholesterol, glucose, urea, uric acid, and cortisol. These values were compared with values obtained with highly accurate reference methods based on isotope dilution-mass spectrometry. Differences were marked in the case of determination of creatinine and cortisol. Concerning the other components, the differences between the state-of-the-art value and the values obtained with the reference methods were negligible. Moreover, the glucose oxidase and the oxime methods for determination of glucose and urea were found to give significantly lower values than the hexokinase and urease methods, respectively. We conclude that methods with a higher degree of accuracy are required for routine determination of creatinine and cortisol.
A kinetic standard for precise calibration of spectrophotometer cell temperature.
Authors: Adams P A , Berman M C 
Published: January 2020

Abstract
We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).
Suitability of control materials for determination of alpha-amylase activity.
Authors: Bretaudiere J P , Rej R , Drake P , Vassault A , Bailly M 
Published: January 2020

Abstract
The suitability of control materials for determination of alpha-amylase activity was assessed in comparison with reference groups of authentic human serum specimens containing alpha-amylase of either pancreatic or salivary origin, specimens from patients with no pancreatic pathology, and normal specimens to which porcine pancreatic alpha-amylase was added. After determination of alpha-amylase activity by 11 commonly used techniques (five different principles), the results were processed by both classical (linear representation, regression) and multivariate (correspondence analysis, principal-components analysis) statistical techniques. Specimens containing porcine pancreatic alpha-amylase did not behave like any of the other groups. We conclude that porcine enzyme should not be used for interlaboratory quality-control surveys or intermethod comparison studies. Determination of human salivary and pancreatic alpha-amylase showed intermethod biases similar to those for authentic patients' specimens. Human salivary alpha-amylase, both because of its behavior and its commercial availability, is a satisfactory source for alpha-amylase activity of quality-control specimens. The nature of the matrix (polyvinylpyrrolidone, albumin, delipidated serum, bovine serum, or human serum) little influenced the behavior of the specimens for any of the methods studied.
Determination of beta 2-microglobulin in human urine and serum by latex immunoassay.
Authors: Bernard A M , Vyskocil A , Lauwerys R R 
Published: January 2020

Abstract
This highly sensitive method for determination of beta 2-microglobulin (beta 2-m) in human urine or serum is based on direct agglutination by beta 2-m of latex particles on which an antibody against beta 2-m is adsorbed. The agglutination is quantified by counting the remaining unagglutinated particles, or by turbidimetry. A novel aspect of this method is the capability to prevent nonspecific agglutination of the antibody-coated particles by diluting them with an albumin solution of well-defined characteristics (pH, freshness, concentration) just before the assay. The assayable concentration range is 1--32 micrograms/L, the detection limit 0.5 micrograms/L. Within-assay CV, based on 10 determinations of beta 2-m in urine and serum at two different dilutions, ranged from 4.6 to 8.7%. Between-assay CV, calculated from 10 determinations of beta 2-m in urine and serum, was 10 and 8.4%, respectively. Analytical recovery of beta 2-m in urine averaged 97% and in serum 104% (n = 10). No component of urine or serum interfered. Coefficients of correlation for beta 2-m in urine or serum as measured by radioimmunoassay and latex immunoassay were 0.97 and 0.93, respectively. Concentrations of beta 2-m in serum and urine from 33 healthy men (ages 20 to 67 years) averaged 1.5 mg/l and 54 micrograms/g of creatine, respectively.
Quantitative differences in volatiles from healthy mouths and mouths with periodontitis.
Authors: Kostelc J G , Zelson P R , Preti G , Tonzetich J 
Published: January 2020

Abstract
It has been suggested that orally derived volatile aromatic amines may be of possible diagnostic use and may contribute to the etiology or pathogenesis of periodontal disease. Using gas chromatography and gas chromatography/mass spectrometry, we identified and quantitated pyridine and picolines in the headspace of incubated whole saliva from healthy and diseased subjects. The oral health of subjects was evaluated by four standard oral-health indices. Volatile aromatic amines were virtually absent from subjects with healthy oral cavities, but were present in the oral cavities of subjects with periodontitis to the extent of 636.4 (SEM 154.7) ng/5 mL of saliva. Pyridine and picolines in saliva of diseased subjects may be related to the disease process.
Alternatives to radioimmunoassay: labels and methods.
Authors: Schall R F , Tenoso H J 
Published: January 2020

Abstract
We review the following labels used as substitutes for radioisotopes in immunoassay systems: bacteriophages, chemiluminescence precursors, fluorochromes, fluorogens, fluorescence quenchers, enzymes, coenzymes, inhibitors, substrates, various particulates, metal atoms, and stable free radicals. New methods for performing immunoassays with these labels are described where appropriate. Methods that require no separation steps and offer special promise for easy automation are noted.
Fluoroimmunoassay of progesterone in human serum or plasma.
Authors: Allman B L , Short F , James V H 
Published: January 2020

Abstract
We describe a fluoroimmunoassay for progesterone in serum or plasma. The assay involves use of an antiserum to progesterone-11-hemisuccinate and a labeled antigen prepared by linking fluoresceinamine to progesterone-3-carboxymethyloxime by use of a mixed-anhydride procedure. Serum or plasma samples are extracted with hexane. After incubation of a portion of the evaporated extract with antiserum and labeled antigen, antibody-bound and free antigen are separated and the fluorescence of the bound fraction is measured. Separation is effected either by using ammonium sulfate to precipitate liquid-phase antiserum or by using a solid-phase antiserum: antiserum covalently linked to magnetizable cellulose particles, which are separated with a magnet. With either separation technique, analytical recovery, linearity, and precision were acceptable and results compared satisfactorily with those obtained with a conventional radioimmunoassay. The solid-phase assay is more precise and more technically convenient, but the performance of both fluoroimmunoassays was adequate for clinical use in the detection of ovulation.
Automated particle-counting immunoassay for digoxin.
Authors: Collet-Cassart D , Magnusson C G , Cambiaso C L , Lesne M , Masson P L 
Published: January 2020

Abstract
We describe a non-radioisotopic automated immunoassay for serum digoxin in the therapeutic range at 50 samples per hour by use of the particle-counting immunoassay technique and a special reagent, rheumatoid factor. Digoxin is determined by evaluating its inhibitory activity on the agglutination of digoxin-coated latex particles. The agglutinating system consists of the anti-digoxin IgG mixed with rheumatoid factor. This anti-IgG autoantibody reacts with IgG when they are aggregated or bound to a surface. Interference by serum proteins was prevented by pepsin digestion at 37 degrees C. Correlation with radioimmunoassay was r = 0.94 for 109 samples with concentrations between 0 and 5.7 micrograms/L. Analytical recovery overall averaged 102%. Within-assay precision (CV) ranged from 12.5% at 0.96 micrograms/L to 4.4% at 2.97 micrograms/L; between-assay precision varied from 8.4% at 0.75 micrograms/L to 5.8% at 2.92 micrograms/L.
Determination of clovoxamine concentration in human plasma by electron capture gas chromatography.
Authors: Hurst H E , Jones D R , Jarboe C H , deBree H 
Published: January 2020

Abstract
The antidepressant drug clovoxamine can be specifically and sensitively quantitated in human plasma by electron capture gas chromatography. Clovoxamine and the internal standard fluvoxamine are extracted into ethyl acetate from plasma at pH 12, back-extracted into phosphoric acid, and hydrolyzed at 90 degrees C to form ketone derivatives, which are then re-extracted into hexane for injection into the chromatograph. As little as 1 microgram of clovoxamine per liter of plasma can be measured. The coefficients of variation (CV) for th analysis at concentrations of 10 and 100 micrograms/L are respectively: within-run, 5.4% and 2.7%; between-run, 17.5% and 7.0%. When this assay was applied to plasma from individuals involved in an early clinical trial of clovoxamine, steady-state plasma concentrations ranged from 50 to 77 micrograms/L 3 h after a 50-mg oral dose of clovoxamine fumarate.
Further studies on plasma proteins, lipids, and dye- and drug-binding in a child with analbuminemia.
Authors: Frohlich J , Pudek M R , Cormode E J , Sellers E M , Abel J G 
Published: January 2020

Abstract
A previously reported patient with analbuminemia was re-investigated after 4 1/2 years, at age 6. The serum albumin concentration was 150 mg/L by radioimmunoassay. Most of the observed increase in total plasma protein over the 4 1/2 years was attributable to gamma-globulin. Concentrations of total and high-density lipoprotein cholesterol were increased; the esterified:free ratio and the lecithin-cholesterol acyltransferase activity were both normal. Albumin is apparently not essential for binding of lysolecithin generated by the acyltransferase-catalyzed reaction. The binding of bromphenol blue suggested that analbuminemic serum has about 25% of normal binding capacity for bilirubin (more than expected in a patient with analbuminemia), which may explain why newborns with this disorder do not develop kernicterus. Binding by the patient's plasma of diazepam (1020 mg/L) and warfarin (1040 mg/L), which bind primarily to albumin, as well as of propranolol (1.05 g/L), which binds primarily to alpha 1-acid glycoprotein, was also studied. The proportions of free diazepam (14.4%) and warfarin (4.8%) were about 10-fold normal. In contrast, the proportion of propranolol in the free form was decreased (4.5%). Evidently, other plasma proteins are partly compensating for the deficiency of albumin.
Determination of serum 17 alpha-hydroxyprogesterone by liquid chromatography.
Authors: Canalis E , Caldarella A M , Reardon G E 
Published: January 2020

Abstract
17 alpha-Hydroxyprogesterone, cortisol, and 11-deoxycortisol were extracted with methylene chloride, separated by liquid chromatography, identified by their retention times, and quantitated by monitoring the absorbance at 254 nm. The method is specific and sensitive to as little as 2.5 ng of 17 alpha-hydroxyprogesterone. Mean analytical recovery of added 17 alpha-hydroxyprogesterone was 99% (SD 11%) and the CV for the same or different assays ranged from 3.5 to 9.4%. 6 beta-Hydroxyprogesterone was used as the internal standard. Concentrations of 17 alpha-hydroxyprogesterone in serum of normal men and women were less than 2.5 micrograms/L, but women in the luteal phase of the menstrual cycle had higher values. Mean 17 alpha-hydroxyprogesterone content in serum from mixed cord blood of normal newborns was 28.1 (SD 13.8) micrograms/L. Results by this method correlated well (r = 0.97) with results by radioimmunoassay, but were somewhat higher.
Evaluation of a commercial kit for microchromatographic quantitation of hemoglobin A2 in the presence of hemoglobin S.
Authors: Baine R M , Brown H G 
Published: January 2020

Abstract
Commercial microcolumns introduced in 1976 by Helena Laboratories ("Hb A2 Quik Column") and by Isolab, Inc. ("Quik-Sep") provide a rapid, simple, accurate method for quantitation of hemoglobin A2 (Hb A2). However, these kits cannot be used for the quantitation of Hb A2 in the presence of slow-moving variants such as Hb S. Recently, Isolab, Inc., produced a new kit ("Quik-Sep Improved Hb A2 Test") for quantitation of both Hb A2 and Hb S. We compared results obtained with the new Isolab kit to results obtained with the original Tris/HCl method for quantitation of Hb A2 and Hb S. Blood was drawn from persons with sickle cell trait (A/S), sickle cell anemia (S/S), sickle cell/beta+ thalassemia (S/beta+ thal) and sickle cell/beta 0 thalassemia (S/beta 0 thal) and percentages of Hb A2 and Hb S were determined by each method. We found no significant differences in Hb A2 percentages by the two methods, and the coefficients of variation were similar. Both methods showed only slight overlap of Hb A2 values from subjects with some form of beta thalassemia and those with A/S or S/S. However, the Tris/HCl method consistently gave values for Hb S that were higher and closer to those expected, suggesting that the Isolab kit does not accurately quantitate Hb S.
Assay for plasma 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 by "high-performance" liquid chromatography.
Authors: Dabek J T , Härkönen M , Wahlroos O , Adlercreutz H 
Published: January 2020

Abstract
We describe a new, rapid, and simple column-chromatographic procedure for 25-OH vitamin D3 in plasma. The vitamin is extracted by use of Sep-pak C18 (octadecyl alkylated silicic acid), a short factory-packed reversed-phase column, and 25-OH vitamin D2 + 25-OH vitamin D3 fraction is eluted with methanol/water. The 25-OH D2 and 25-OH D3 are then well resolved on a high-resolution 3-micrometer silicic acid straight-phase liquid-chromatography column. The peaks are quantified against a 25-OH D3 standard by ultraviolet absorbance. Recovery was assessed by use of tritiated 25-OH D3. The within-assay coefficient of variation of the method was 5% and recovery 93%. The method was evaluated with 26 samples from control subjects and 17 samples from patients, seven with liver disease and 10 who had undergone ileo-ileostomy for hypercholesterolemia. The normal seasonal variation was observed for 25-OH D3 concentrations, and they correlated negatively and significantly with those of 25-OH D2. Post-ileo-ileostomy concentrations of 25-OH D3 in plasma were generally similar to those in normal individuals for the same reason (winter), but 25-OH D2 concentrations were insignificantly lower. The patients with chronic liver disease had significantly lower 25-OH D3 concentrations than normal persons but higher 25-OH D2 concentrations, with a significantly higher 25-OH D2/25-OH D3 ratio, indicating poor storage of vitamin D3.
Immunochemiluminometric assay for hepatitis B surface antigen.
Authors: Schroeder H R , Hines C M , Osborn D D , Moore R P , Hurtle R L , Wogoman F F , Rogers R W , Vogelhut P O 
Published: January 2020

Abstract
A novel "sandwich" immunoassay for hepatitis B surface antigen monitored by chemiluminescence is described. The method involves use of an antibody-coated microtitration plate and requires 100 micro L of test specimen. The antigen binds to the antibody during the first 2-h incubation and, after an intermediate wash step, the sandwich is completed by 2-h incubation with antibody to antigen that has been labeled with an isoluminol derivative. A final wash step follows. A luminometer, built in-house, adds "microperoxidase" and peroxide, to initiate chemiluminescence, and provides automated readout at 10-s intervals. Results compare well in specificity and sensitivity with those of a comparison radioimmunoassay procedure. Within- and between-assay variability (CV) is 7 to 13% (n = 6). All reagents are stable at 4 degrees C for at least several months. Use of a non-radioisotopic label in this assay avoids the stability problems and inconvenience associated with radioactivity.
Urinary urobilinogen determined by a mercuric chloride procedure.
Authors: Rupe C O , Fetter M C 
Published: January 2020

Abstract
In this quantitative assay, urinary urobilinogen is oxidized to urobilin with iodate in an acid medium, the pH is adjusted to 6 with sodium acetate, and the mixture is reacted with alcoholic HgCl2 solution, extracted with CHCl3, the measured spectrophotometrically at 513 nm. The artificial standards of previous methods have been replaced with crystalline stercobilin IX (commercially available), a urobilin closely related to the urinary urobilins. The reproducibility of the method, as assessed from 10 replicates of a single urine specimen to which urobilinogen was added, gave a coefficient of variation of 3.9%. Analytical recovery of urobilinogen added to urines was 90.4% (SD 14.5%). Bilirubin, biliverdin, mesobilirubin, coproporphyrin I, uroporphyrin I, and porphobilinogen do not interfere.
Radioimmunoassay for plasma thromboxane B2.
Authors: McCann D S , Tokarsky J , Sorkin R P 
Published: January 2020

Abstract
Platelet activity may play a major role in the acute phase of atherosclerotic cardiovascular disease. To assess such activity, an assay for plasma thromboxane B2, a prostaglandin metabolite unique to platelets, is needed. The radioimmunoassay described here is based on a nonequilibrium incubation followed by a solid-phase second-antibody separation of bound from free thromboxane B2. No prior purification is required. Values for 22 normal subjects averaged 39.0 (SD 24.6) ng/L. The thromboxane B2 concentration of a plasma sample was 20.3 ng/L as compared with 37 micrograms/L in the corresponding serum. Plasma thromboxane B2 concentrations before and after ingestion of aspirin differed significantly (p less than 0.025). The biological half-life of intravenously injected [3H]thromboxane B2 in rabbits was 20 min. At the end of 2 h, 85% of the label was accounted for in urine, 7% in liver, and 5% in lung. Our assay is simple, reproducible, sensitive, and specific. It can be used to reflect acute events involving platelet aggregation.
Two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper.
Authors: Miyai K , Ishibashi K , Kawashima M 
Published: January 2020

Abstract
We describe a sensitive, simple, and rapid two-site immunoenzymometric assay for thyrotropin in dried blood samples on filter paper, for use in screening for neonatal primary hypothyroidism. In this method, two dried-blood spots of 3 mm diameter (equivalent to about 5.4 microliter of blood) are incubated overnight with anti-thyrotropin-beta-D-galactosidase complex in an anti-thyrotropin coated tube. Then the enzyme activity in the washed tube is determined fluorophotometrically. The range of thyrotropin measurable is 10 to 160 milli-int. units/L blood. Values for thyrotropin in dried blood samples determined by this method and those determined by radioimmunoassay correlated highly (r = 0.96).
Ferrozine iron and total iron-binding capacity method adapted to the ABA-100 Bichromatic Analyzer.
Authors: Mori L , Bekkering A , Traini J , Vanderlinden L 
Published: January 2020

Abstract
A sensitive method (Clin. Chem. 26: 327--331, 1980) for serum iron, in which the color reagent Ferrozine is used, is modified and adapted to the Abbott ABA-100 discrete analyzer. The standard curve is linear to at least 10 mg/L and the method showed day-to-day precision (CV) of 2.4% for a 1.03 mg/L sample (n = 63) and 1.9% for a 2.13 mg/L sample (n = 63). Lower values were obtained than with the modified continuous-flow technique of Giovanniello et al., but the correlation was good (r = 0.98). Bilirubin and copper do not interfere; hemoglobin and gross lipemia interfere only slightly. The total iron-binding capacity, based on Ramsay's method, was evaluated with regard to the effect of adding various amounts of magnesium carbonate. Results led us to use a ratio of approximately 180 mg of magnesium carbonate to each 5 micrograms of excess iron added. Day-to-day, the method for total iron-binding capacity gave a CV of 3.1% for a 2.55 mg/L sample, 2.8% for a 3.63 mg/L sample.
Direct determination of plasma copper and zinc in infants by atomic absorption with discrete nebulization.
Authors: Makino T , Takahara K 
Published: January 2020

Abstract
A new micromethod for the determination of copper and zinc is presented. Sample volumes can be as little as 10 (Cu) and 20 (Zn) microliter of plasma or serum, by using discrete (small sample volume) nebulization in place of conventional nebulization in place of conventional nebulization in atomic absorption spectrometry. The present method has slightly poorer precision than the conventional nebulization method, but has the advantages of requiring commercially available apparatus without any modification, involving simple sample preparation, and being time-saving. Results agree well with those by the trichloroacetic acid deproteinization method. In addition, this method is useful for pediatric samples, and we report reference intervals for full-term and premature infants, as well as adults.
Induction of O-deethylase activity as an index to exposure to coal-derived products and trace environmental pollutants.
Authors: Bostick W D , Kao J , Holland J M , Mrochek J E 
Published: January 2020

Abstract
The metabolism of the synthetic substrate 7-ethoxyresorufin is a selective measure of the activity of cytochrome P-448 monooxygenase, the subset of cytochrome P-450-mediated enzymes preferentially induced by polycyclic aromatic hydrocarbons and related compounds. 7-Ethoxycoumarin metabolism, on the other hand, reflects total (nonselective) cytochrome P-450 monooxygenase activity. Either substrate yields a single, highly fluorescent product, amenable to direct, sensitive assay with the portable centrifugal analyzer. We used three assays with liver microsomes from C57/BL6 mice for the short-term bioassay of the dose-dependent effects of exposure to selected environmental toxins, including petroleums, polychlorinated biphenyls, and their oxidative degradation products.
Design and evaluation of statistical control procedures: applications of a computer "quality control simulator" program.
Authors: Westgard J O , Groth T 
Published: January 2020

Abstract
A computer simulation program has been developed to aid in designing and evaluating statistical control procedures. This "QC stimulator" (quality control) program permits the user to study the effects of different factors on the performance of quality-control procedures. These factors may be properties of the analytical procedure, characteristics of the instrument system, or conditions for the quality-control procedure. The performance of a control procedure is characterized by its probability for rejection, as estimated at several different magnitudes of random and systematic error. These performance characteristics are presented graphically by power functions-plots of the probability for rejection vs the size of the analytical errors. The utility of this stimulation tool is illustrated by application to multi-rule single-value procedures, mean and range procedures, and a trend analysis procedure. Careful choice of control rules is necessary to minimize false rejections and to optimize error detection with multi-rule procedures. Control limits must be carefully calculated for optimum performance of mean and range procedures. The level of significance for testing control must be carefully selected for the trend analysis procedure.