bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of a between-run component of variation, choice of control limits, and shape of error distribution on the performance characteristics of rules for internal quality control.
Authors: Westgard J O , Falk H , Groth T 
Published: January 2020

Abstract
A computer-stimulation study has been performed to determine how the performance characteristics of quality-control rules are affected by the presence of a between-run component of variation, the choice of control limits (calculated from within-run vs. total standard deviations), and the shape of the error distribution. When a between-run standard deviation (Sb) exists and control limits are calculated from the total standard deviation (St, which includes Sb as well as the within-run standard deviation, Sw), there is generally a loss in ability to detect analytical disturbances or errors. With control limits calculated from Sw, there is generally an increase in the level of false rejections. The presence of non-gaussian error distribution appears to have considerably less effect. It can be recommended that random error be controlled by use of a chi-square or range-control rule, with control limits calculated from Sw. Optimal control of systematic errors is difficult when Sb exists. An effort should be made to reduce Sb, and this will lead to increased ability to detect analytical errors. When Sb is tolerated or accepted as part of the baseline state of operation for the analytical method, then further increases in the number of control observations will be necessary to achieve a given probability for error detection.
Liquid-chromatographic determination of acetaminophen in serum.
Authors: Fletterick C G , Grove T H , Hohnadel D C 
Published: January 2020

Abstract
We describe a sensitive and precise "high-pressure" liquid-chromatographic method for determining acetaminophen in serum. The 2-acetaminophenol and 3-acetaminophenol structural isomers of acetaminophen are used as internal standards. The method, which involves solvent extraction and adsorption chromatography on silica, provides excellent sensitivity, accuracy, and selectivity. The standard curve is linear over the range of acetaminophen concentrations of 0.5 to 300 mg/L, which makes the method useful for both pharmacokinetic studies and overdose monitoring. Analytical recovery is 97% for acetaminophen concentrations ranging from 5 to 300 mg/L. Many commonly used drugs were tested and found not to interfere. The procedure has been successfully adapted as a microscale method requiring only 50 microL of sample. The microscale method is particularly useful for pediatric and neonatal patients for whom sample size is a major concern.
Cytosine and orotic acid in urine of immunodeficient children.
Authors: Mills G C , Schmalstieg F C , Newkirk K E , Goldblum R M 
Published: January 2020

Abstract
We describe procedures for determining cytosine and orotic acid in urine. We determine cytosine by cation-exchange analysis with either HCl or pH 5.2 buffer as eluent. Orotic acid is first separated by an anion-exchange separative procedure; after lyophilization, the product is subjected to "high-pressure" liquid chromatography for further separation and detection. We analyzed urine from normal subjects and from immunodeficient children. Three children with severe combined immunodeficiency had increased levels of cytosine in urine (23-160 mmol/mol creatinine); one child with severe combined immunodeficiency and two children with other immunodeficiencies had normal urinary levels (less than 2 mmol/mol creatinine). Orotic acid excretion in urine was normal (1-5 mmol/mol creatinine) in all of th immunodeficient children. We discuss the possible significance of the increased cytosine excretion in the three children with severe combined immunodeficiency.
Importance of blood-collection tubes in plasma lidocaine determinations.
Authors: Stargel W W , Roe C R , Routledge P A , Shand D G 
Published: January 2020

Abstract
In 25 clinical samples serum lidocaine concentrations fell from a mean of 6.5 +/- 2.1 mg/L (mean +/- SD) to 4.9 +/- 1.8 mg/L (p less than 0.001) when the blood sample was allowed to make contact with the stopper of the Vacutainer collection tube. In vitro experiments showed that this effect of the stopper occurred only with whole blood and was dependent on sample concentration. The plasma binding of lidocaine decreased from a normal value of 56% +/- 2.2 (mean +/- SD) to 28% +/- 2.2 (p less than 0.001) when exposed to the Vacutainer stopper. We conclude that a chemical leached from such stoppers displaces lidocaine from its plasma-binding sites and that the drug is then redistributed into the erythrocytes, producing spuriously low lidocaine concentrations in plasma or serum. Such artifacts are important in therapeutic drug monitoring and can lead to erroneous clinical decisions.
Relative stabilities of purified human mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase in lyophilized materials.
Authors: Sampson E J , McKneally S S , Whitner V S , Burtis C A , Bayse D D 
Published: January 2020

Abstract
Eight different pools of purified human mitochondrial and cytoplasmic isoenzymes of aspartate aminotransferase were prepared, to examine the effects of the following matrix variables: the matrix support material (bovine serum albumin and polyvinylpyrrolidone), endogenous pyridoxal concentration, and azide as an antimicrobial preservation. Storage temperatures of 25 and 37 degrees C were used as a rapid and convenient means of accelerating the degradation process. Activity of the enzyme was measured with and without pyridoxal in the reaction solution. We found that the mitochondrial isoenzyme was consistently more labile than the cytoplasmic isoenzyme under identical storage conditions. Both isoenzymes were more stable in matrixes containing bovine serum albumin than in those containing polyvinylpyrrolidone. No apparent difference in the stability of either isoenzyme was observed at matrix pyridoxal concentrations of 15 micromol/L and 150 micromol/L. Only the mitochondrial isoenzyme in matrixes containing bovine serum albumin and 15 micromol of pyridoxal per liter had increased activity (about 9%) when pyridoxal was added to the enzymatic reagent. The amount of activity in reconstituted specimens did not apparently change after 72 h at 4 degrees C.
A simple, direct radioimmunoassay for plasma cortisol, featuring a 125I radioligand and a solid-phase separation technique.
Authors: Riad-Fahmy D , Read G F , Gaskell S J , Dyas J , Hindawi R 
Published: January 2020

Abstract
A simple, direct radioimmunoassay for cortisol in human serum and plasma is described. An antiserum, raised in sheep to a cortisol-3-(O-carboxymethyl)oxime/bovine serum albumin conjugate, is coupled to microcellulose. No extraction is required because plasma samples and standards are incubated with the antiserum and an 125I radioligand in a low-pH buffer, which denatures cortisol-binding globulins. The assay satisfies accepted validation criteria. In addition, results from the radioimmunoassay compare well with those obtained by a gas chromatographic-mass spectrometric technique (r = 0.968; FRIA = 0.97 FGCMS + 2.0 nmol/L). The latter procedure features the very high intrinsic specificity obtained by selected ion monitoring at high mass-spectrometric resolution (M/deltaM = 8500) with a Varian MAT-731 instrument. The simplicity of the radioimmunoassay procedure, with use of reagents prepared "in house," makes this a very practical and economical assay for use in the medium or large endocrine laboratory.
Outliers in clinical chemistry quality-control schemes.
Authors: Healy M J 
Published: January 2020

Abstract
Results submitted to large-scale quality-control schemes are commonly judged against the mean and standard deviation (SD) of the results from other laboratories. It is desirable to ignore outlying values in estimating this mean and standard deviation, and results more than 2.5 or 3 SD from the mean are commonly rejected. I show that an outlier can so inflate the estimated SD that its presence is not detected by this method. Alternative estimators that are less influenced by outliers are described, and their application to quality-control data is discussed.
Elemental composition of platelets. Part III. Determination of Ag, Au, Cd, Co, Cr, Cs, Mo, Rb, Sb, and Se in normal human platelets by neutron activation analysis.
Authors: Kasperek K , Iyengar G V , Kiem J , Borberg H , Feinendegen L E 
Published: January 2020

Abstract
The elements Ag, Au, Cd, Co, Cr, Cs, Mo, Rb, Sb, and Se were determined in platelets from seven normal donors. The results, in ng/g wet weight, for plasma-free platelets follow: "Pure" platelets: Ag = 29 +/- (18), au = 0.22 +/- (0.22), Cd = 6.2 +/- 3.4, Cs = 54.8 +/- 19.2, Cr = 6.1 +/- 2.5, Co = 7.5 +/- (5.0), Mo = 3.4 +/- 1.3, Rb = 10400 +/- 3000, Sb = 18 +/- (26), and Se = 782 +/- 127. "Impure" platelets: Au = 0.23 +/- (0.28), Cd = 6.4 +/- 2.6, Cs = 35.2 +/- 13.8, Cr = 8.2 +/- 2.9, Co = 2.9 +/- (3.0), Mo = 3.2 +/- 0.8, Rb = 8700 +/- 1700, Sb = 13.2 +/- (8.7), and Se = 679 +/- 57. To our knowledge, none of these 10 trace elements has been determined in platelets before. The selenium concentration in platelets exceeds that in other tissues (e.g., liver). We suggest that glutathione peroxidase or other unknown selenoenzymes are particularly important in platelet metabolism. Platelets are crucial for triggering thrombosis, and so may be involved as links between selenium deficiency and the concomitant increased death rate from cardiovascular disease.
Limitations of immunochemical measurement of ceruloplasmin.
Authors: Buffone G J , Brett E M , Lewis S A , Iosefsohn M , Hicks J M 
Published: January 2020

Abstract
We describe a quantitative immunochemical method for the nephelometric measurement of ceruloplasmin. Results are compared with those from a radial immunodiffusion technique. We examine factors affecting the results, such as antiserum source and calibrators, and list reference limits for a pediatric population.
Evaluation of automated enzyme immunoassays for five anticonvulsants and theophylline adapted to a centrifugal analyzer.
Authors: Urquhart N , Godolphin W , Campbell D J 
Published: January 2020

Abstract
We report a clinical evaluation of the enzyme immunoassay (EMIT) performed with the GEMSAEC centrifugal analyzer as compared to gas-liquid and liquid chromatography for anticonvulsant drugs and theophylline, respectively. A good correlation was obtained for all drugs, although some difficulties were experienced with one lot of reagent for ethosuximide. The analyzer has an economic advantage if many samples are being analyzed for few drugs in each sample.
An evaluation of the detection capacity of a computer-assisted real-time delta check system.
Authors: Sher P P 
Published: January 2020

Abstract
We developed of computer programs to evaluate the clinical reliability of test results by comparing each new result with previous results for the same patient, and to signal discrepancies in real time. These "delta check" discrepancies are noted, and they must be reviewed by the laboratory staff before results can appear on a patient's record. During a month, I reviewed 1403 such delta check messages and detected 55 (3.9%) that could not be explained on the basis of the patient's clinical condition. Of these, 23 represented true laboratory errors, which were corrected. The recognition of discrepancies before they appear on patients' reports has facilitated the operation of the clinical chemistry laboratory. Mislabeled and otherwise mishandled specimens are discovered before erroneous results appear on a patient's record.
Application of Bayes's theorem to results of quantitative clinical chemical determinations.
Authors: van der Helm H J , Hische E A 
Published: January 2020

Abstract
The diagnostic implication of a certain test result with regard to a certain condition can be expressed as a single number, L, the likelihood ratio of this result. This ratio allows Bayes's theorem to be written in a convenient form. We show that the practice of calculating predictive values for the results of quantitative tests by use of discrimination limits leads to incorrect predictive values. Including L values in laboratory reports seems a more logical approach to optimum interpretation of laboratory results than the use of discrimination values.
Creatine kinase B-subunit activity in serum after immunoinhibition of M-subunit activity.
Authors: Gerhardt W , Waldenström J 
Published: January 2020

Abstract
Creatine kinase (EC 2.7.3.2) B-subunit activity in serum may be routinely measured as residual activity after specific immunoinhibition of the M-subunit. We assessed the inhibition kinetics, specificity, completeness of inhibition, and inhibitory capacity of three different anti-M preparations, with use of isolated human BB, MM, and MB isoenzymes. The Scandinavian-recommended reaction system was used. We suggest a set of tentative quality requirements for anti-M for use in diagnosing acute myocardial infarction. The need to measure and subtract sample residual adenylate kinase activity was demosntrated. We describe a routine photometric method for determining B-subunit activity in serum. With the Scandinavian CK method the upper reference value for total creatine kinase in serum was found to be 150 U/L for women, 270 U/L for men. By bioluminescence, we found the upper reference value for B-subunit activity to be 6 U/L for both sexes. We discuss three different modes for applying B-subunit determinations to the diagnosis of acute myocardial infarction.
Urinary excretion of conjugated homovanillic acid, 3,4-dihydroxyphenylacetic acid, p-hydroxyphenylacetic acid, and vanillic acid by persons on their usual diet and patients with neuroblastoma.
Authors: Muskiet F A , Groen A 
Published: January 2020

Abstract
We report quantitative data on beta-glucuronidase- and sulfatase-hydrolyzable conjugates of homovanillic acid, 3,4-dihydroxyphenylacetic acid, p-hydroxyphenylacetic acid, and vanillic acid in the urine of 20 apparently normal and healthy control persons and of three patients with neuroblastoma. We used organic solvent extraction and capillary gas chromatography. There was considerable person-to-person variation in the conjugation percentages calculated. Mean conjugated percentages of the four compounds for 16 normal healthy persons 2.5--40 years of age were, respectively, 12%, 33%, 14%, and 35%. For newborns and patients with neuroblastoma, these percentages were somewhat different. Increased amounts of vanillic acid were found in the urine of the patients with neuroblastoma, but results of a small metabolic study in rats suggest that this increase most probably is of dietary origin.
Comparison of acid phosphatase isoenzymes of human seminal fluid, prostate, and leukocytes.
Authors: Lam W K , Yam L T , Wilbur H J , Taft E , Li C Y 
Published: January 2020

Abstract
We used ion-exchange column chromatography and electrophoresis on polyacrylamide gel to compare the acid phosphatase isoenzymes of prostate and leukocytes. The major isoenzyme of the prostate is band 2A; only a trace of band 2B was observed. However, the major isoenzymes of leukocytes are band 4 and band 2B, and only a small amount of band 2A was observed. The three isoenzymes isolated from leukocytes or prostate gland react to the antiserum prepared against the aicd phosphatase isoenzyme of seminal fluid. Acid phosphatases of leukocytes other than the three isoenzymes mentioned above did not interact with the antiserum.
Micro-scale method for liquid-chromatographic determination of chloramphenicol in serum.
Authors: Petersdorf S H , Raisys V A , Opheim K E 
Published: January 2020

Abstract
We describe the use of "high-performance" liquid chromatography to measure chloramphenicol in as little as 25 microL of serum. Serum is treated to precipitate proteins with acetonitrile containing p-nitroacetanilide as an internal standard. Chloramphenicol is eluted with a mobile phase of methanol in pH 7.0 phosphate buffer (35/65 by vol). The drug is measured at 278 nm and simultaneously monitored at 254 nm; interfering substances are detected by examining the 278 nm/254 absorbance ratios. This method is sensitive to less than 0.5 mg/L and the standard curve is linear to at least 50 mg/L. Inter-day precision ranged between 3--6%. We encountered no interference from endogenous compounds or from other drugs we tested.
Evaluation of a solid-phase enzyme immunoassay for insulin in human serum.
Authors: Kato K , Umeda Y , Suzuki F , Hayashi D , Kosaka A 
Published: January 2020

Abstract
We describe a "sandwich-type" enzyme immunoassay for insulin in serum, in which antibody Fab'-beta-D-galactosidase conjugate and an antibody-immobilized silicone rubber solid-phase are used. The interference by serum factors with the solid-phase enzyme immunoassay can now be removed by using a buffer containing gelatin. Serum samples of 50 microL can be analyzed by the enzyme immunoassay, which is as sensitive as radioimmunoassay for human insulin. Our results correlate well with those for radioimmunoassay (r = 0.97, slope = 0.92, y-intercept = 4.6 milli-int. units /L for 181 samples). Between-assay and within-assay coefficients of variation are less than 15% over the useful ranges of the assay (5--160 milli-int. units/L).
Urinary excretion of thymine and uracil in a two-year-old child with a malignant tumor of the brain.
Authors: Berglund G , Greter J , Lindstedt S , Steen G , Waldenström J , Wass U 
Published: January 2020

Abstract
A two-year-old boy with a malignant tumor of the brain (medulloblastoma) excreted large amounts of thymine and uracil in his urine. The excretion was related to progress and regress of the disease, and reached a maximum of 3.0 mol of thymine per mole of creatinine and 2.6 mol of uracil per mole of creatinine. The excretion by 20 apparently normal children was less than 0.01 mol/mol of creatinine for each of the two pyrimidines. Three children with brain tumors, two with leukemias, and one with neuroblastoma were also studied; two of them had a moderate increase in urinary pyrimidine excretion, but only up to 0.07 mol/mol of creatinine. The activity of dihydrouracil dehydrogenase (NADP+) (EC 1.3.1.2) in cultured fibroblasts from the patient was somewhat lower than in control fibroblasts. The tumor was considered to be the likely cause of the increased excretion of pyrimidines, but an impaired degradation of pyrimidines in the liver could not be ruled out.
Diabetic ketoalkalosis.
Authors: Koett J , Howell J , Steinberg S , Wolf P 
Published: January 2020

Abstract
The usual metabolic derangement in uncontrolled diabetes mellitus is metabolic acidosis, with an increase in the anion gap because of increased ketoacids and lactate. However, diabetic ketoalkalosis may occasionally be encountered, the prominent clinical feature of which is vomiting, with depletion of potassium, chloride, and hydrogen ions. Self-medication with absorbabe alkali may also contribute to the alkalosis. It would be dangerous to treat hyperlgycemic patients with alkali if their condition is ketoalkalosis instead of ketoacidosis.
Enzymic assay for serum theophylline.
Authors: Vinet B , Zizian L 
Published: January 2020

Abstract
We describe an original procedure for determination of theophylline in serum. The drug is extracted from 0.4 mL of serum at pH 7.4 with chloroform/isopropanol (20/1 by vol) and back-extracted into sodium hydroxide (1 mmol/L). The inhibition of beef-liver alkaline phosphatases by theophylline in this alkaline phase is measured at 25 degrees C, with p-nitrophenyl phosphate as substrate, in 2-amino-2-methyl-1-propanol buffer, pH 9.4- The reciprocal of enzyme activity and theophylline concentration are linearly related in the range 2 to 60 mg/L. The maximum interference to be expected from 3-methylxanthine would increase apparent theophylline concentration by no more than 1 mg/L. The method is accurate, free of interference by other xanthines and often-coadministered drugs, and results correlate well with those by the immunoenzymic assay. Major advantages are reagent stability, low cost, and simplicity of instrumentation.
Spectrophotometric measurement of carboxyhemoglobin and methemoglobin in blood.
Authors: Rodkey F L , Hill T A , Pitts L L , Robertson R F 
Published: January 2020

Abstract
This paper describes separate spectrophotometric procedures for rapidly measuring carboxyhemoglobin (COHb) and methemoglobin (MetHb) in blood. Absorbance measurements are made in the Soret region at a blood dilution near 1000-fold. For COHb estimation, the diluent contains sodium hydrosulfite, providing the two-component system COHb--Hb for absorbance measurements at 420 and 432 nm. The NA2S2O4 effectively prevents dissociation of COHb by oxygen. For MetHb estimation, the diluent contains KCN and carbon monoxide, providing the two-component system COHb--CNMetHb. Absorbance measurements are made at 420 nm, before and after addiely analyzed for the total of all MetHb forms present. Each procedure requires about 3 muL of blood and can be applied to human or animal blood. Results obtained by the present methods are in satisfactory agreement with currently accepted procedures, which require much larger samples or more elaborate equipment.
Improved double-antibody enzyme immunoassay for methotrexate.
Authors: Al-Bassam M N , O'Sullivan M J , Bridges J W , Marks V 
Published: January 2020

Abstract
We report an enzyme immunoassay procedure for methotrexate measurement that takes less than 3 h to perform. beta-D-Galactosidase (EC 3.2.1.23) from Escherichia coli was conjugated to methotrexate by means of the mixed anhydride reaction. Bound and free labeled drug were separated by a preincubated cubic complex of first and second antibody. The enzyme activity of the bound fraction was measured with o-nitrophenyl-beta-D-galactopyranoside as substrate. The standard curve covered the range 1 to 10 micrograms of methotrexate per liter. One microgram of methotrexate per liter inhibited binding of the tracer by 17%. The assay is specific for methotrexate in the presence of folinic acid (citrovorum factor), folic acid, tetrahydrofolic acid, and other methotrexate metabolities. Intra- and inter-assay CVs were less than 5 and 10%, respectively. Results obtained with this enzyme immunoassay method agreed well with those obtained with an established radioimmunoassay method.
Four electrophoretic methods compared for diagnosis of type III hyperlipoproteinemia.
Authors: Kuba K , Lippel K , Frantz I D 
Published: January 2020

Abstract
Blood drawn from 192 probands and 1129 first-degree relatives who were participants in a collaborative family study of hyperlipoproteinemia at nine Lipid Research Clinics was used to prepare aliquots of whole plasma and top (d less than 1.006 g/mL) and bottom (d greater than 1.006 g/mL) ultracentrifugal fractions. Each aliquot was analyzed at a central laboratory by electrophoresis on paper, agarose, and polyacrylamide gel, and by a combined electrophoretic precipitation technique. The electrophoretograms were evaluated for the presence or absence of a "floating-beta" lipoprotein band. All four methods agreed completely for 92.3% of the samples. An additional 2.0% of the samples were in agreement for three electrophoretic methods, but the paper electrophoretic results were not interpretable. Another 1.9% were considered to be "floating-beta" positive by paper electrophoresis but negative by the other three electrophoretic methods.