bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interference of imferon in colorimetric assays for iron.
Authors: Huisman W 
Published: January 2020

Abstract
Imferon (Merrell-National), an iron-dextran complex, is widely used in patients with iron deficiency. It is present in the circulation in appreciable amounts for two to three weeks after administration and interferes with all tested colorimetric iron assays, both with and without deproteinization. The amount of the plasma Imferon iron interference depends primarily on the choice of reductant. With dithionite it is essentially 100%. In the presence of ascorbic acid and hydroxylamine, the interference depends also on assay conditions, especially temperature, but also incubation time and pH. The minimum interference in a homogeneous assay was about 3%. The relative amount of interference from hemoglobin iron under the various assay conditions is different from that of Imferon iron. In the presence of a reducing agent, the dextran-iron complex decomposes--instantaneously with dithionite, and gradually with sulfite, ascorbic acid, and hydroxylamine. The freed iron becomes dialyzable, can react with bathophenanthroline, and elutes on a Sephadex G-50 or G-15 column in the same fractions as an ammonium ferrous sulfate.
Gas-chromatographic determination of disopyramide and its mono-N-dealkylated metabolite in serum with use of a nitrogen-selective detector.
Authors: Bredesen J E 
Published: January 2020

Abstract
I describe a rapid, simple routine gas-liquid chromatographic method for simultaneous isothermal quantitation of disopyramide and its mono-N-dealkylated metabolite. The method involves one extraction step with dichloromethane, derivatization of the metabolite, and gas chromatography with an OV-17 liquid phase. Standard curves were linear over the concentration range tested (0.1-25 mg/L) and the maximum coefficient of variation was 9.2%. Quantitation of both disopyramide and its mono-N-dealkylated metabolite with the present method is less time-consuming than are gas-chromatographic methods previously described.
Fluorometric quantitation of glutamine in cerebrospinal fluid.
Authors: Liu T Z , Khayam-Bashi H 
Published: January 2020

Abstract
We describe a rapid, relatively simple-procedure for fluorometry of glutamine in cerebrospinal fluid. Glutamine is de-aminated with diluted sulfuric acid at 100 °C. The ammonia liberated is then reacted with a buffered o-phthalaldehyde—mercaptoethanol solution, pH 7.4, to form a fluorochrome. Fluorescence is linearly related to the concentration of glutamine from 0.10 to 0.60 g/L (0.68 to 4.10 mmol/l). To prevent interference by endogenous ammonia, each specimen was corrected for its own background fluorescence. The mean analytical recovery was 99.8%. Within-day variation (CV) for pooled, enriched cerebrospinal fluid controls at 0.33 g/L (2.22 mmol/L) and 0.53 g/L (3.63 mmol/L) were 2.2 and 5.1%. Day-to-day variation (CV) for the same controls was 4.4 and 4.8%, respectively. Data obtained by our method correlate excellently (r = 0.980) with those by an established procedure based on the Berthelot (phenol—hypochlorite) reaction.
Plasma methotrexate as determined by liquid chromatography, enzyme-inhibition assay, and radioimmunoassay after high-dose infusion.
Authors: Howell S K , Wang Y M , Hosoya R , Sutow W W 
Published: January 2020

Abstract
Three techniques for measuring methotrexate show various cross reactivities with methotrexate-related compounds: “high-pressure” liquid chromatography, by principle, is virtually specific for methotrexate; the enzyme-inhibition assay quantitates methotrexate, methotrexate diglutamate, and methotrexate triglutamate equally well, but has a 10% cross reactivity with 4-amino-4-deoxy-N10-methylpteroic acid and 1% with 7-hydroxymethotrexate; radioimmunoassay shows an equal cross reactivity with methotrexate, 4-amino-4-deoxy-N10-methylpteroic acid, methotrexate diglutamate and triglutamate, and a 5 to 10% cross reactivity with 7-hydroxymethotrexate. Radioimmunoassay almost always yielded the highest values for methotrexate, followed by enzyme-inhibition assay then liquid chromatography. The presence of two methotrexate-related compounds, 7-hydroxymethotrexate and 4-amino-4-deoxy-N10-methylpteroic acid, was confirmed in human urine samples and quantitated in patients’ plasma by liquid chromatography, the respective maximum plasma concentrations being 250 and 16 mumol/L. Materials cross reacting with methotrexate in radioimmunoassay of chromatographic fractions from plasma were also noted in fractions corresponding to methotrexate diglutamate and triglutamate peaks, in quantities estimated to be 47 and 30 nmol/L methotrexate equivalents, respectively. 7-Hydroxymethotrexate is eliminated more slowly than methotrexate and its production increases with dosages of methotrexate.
Variability in the adsorption properties of microtitre plates used as solid supports in enzyme immunoassay.
Authors: Kricka L J , Carter T J , Burt S M , Kennedy J H , Holder R L , Halliday M I , Telford M E , Wisdom G B 
Published: January 2020

Abstract
We evaluated the variability in the amount of protein adsorbed onto the surface of individual wells of an assortment of microtitre plates by use of procedures involving enzyme-protein conjugates. Coefficients of variation in adsorbed protein ranged from 5.2 to 29.5%. Microtitre plates show a distinct “edge effect”; wells at the edges of a plate adsorb more protein than those in the interior, which markedly affects results from immunoassays involving such plates. In a sandwich enzyme immunoassay the results for an individual sample varied by +/− 18%; in a competitive assay, values read from different calibration curves in the same plate varied by +/− 11%. Scanning electron microscopy and birefringence studies demonstrated no marked physical differences between individual wells on a plate. The variability in the amount of protein adsorbed onto the surface of individual wells on the same microtitre plate seriously affects the reliability and interpretation of results of immunoassays in which such plates are used as solid supports.
The contribution of assays for lymphocyte capping and creatine kinase to detection of the Becker-type dystrophy trait.
Authors: Goldsmith B M , Gruemer H D , Hawley R J , Pickard N A , Verrill H L , Nance W E , Miller G , Crawford R G 
Published: January 2020

Abstract
Members of three unrelated families with the mild Becker type of muscular dystrophy were subjected to lymphocyte capping tests and measurements of serum creatine kinase activity. Both tests correctly identified all nine affected males, but only the capping test was abnormal in seven of eight obligate carriers. The number of capped cells in carriers and affected persons with the Becker-type dystrophy was generally intermediate between those observed for individuals with the Duchenne trait and normal controls, thus potentially aiding in the differential diagnosis between the two myopathies. The lack of sensitivity of measurements of serum creatine kinase activity in identifying carriers is further complicated by the difficulty of establishing reliable reference intervals for this enzyme in 204 healthy controls. Detailed directions for the performance of the capping test are presented.
Isoenzymes of creatine kinase in extracts of various parts and regions of the human central nervous system.
Authors: Petronia R R , Maas A H , van Veelen C W , Staal G E 
Published: January 2020

Abstract
The distribution of isoenzymes of creatine kinase (EC 2.7.3.2.) was investigated by agarose gel electrophoresis of extracts of selected parts and regions of the human central nervous system. Besides the major brain isoenzyme BB, we demonstrated the presence of three other creatine kinase isoenzyme forms. The distribution of creatine kinase isoenzymes depending strongly on the region from which the biopsy was taken. We found substantial amounts of the MB isoenzyme in extracts of the dura from the cauda equina of the two adults examined.
Simplified approach to confidence limited in radioimmunassay.
Authors: Baxter R C 
Published: January 2020

Abstract
A simple method of calculating confidence limits for radioimmunoassay data is presented. The method involves the use of the within-assay variation in dose estimate of three routine quality-control specimens, measured in repeated assays, to estimate the confidence limits for results on unknown samples. Results for control specimens are combined by calculating the unique quadratic curve fitting a graph of within-assay standard deviation vs mean value for each control. This method requires no special data accumulation or advanced computing equipment. For cortisol, lutropin, and thyroxine radioimmunoassays, confidence limits calculated in this way have been compared with those calculated from the variance of the response variable “B/B0” in repeated standard curves. Both methods agree well with actual limits observed when plasma pools containing a wide range of hormone concentrations are assayed repeatedly.
Lamellar body phospholipid content of amniotic fluid and L/S ratio compared in assessing fetal lung maturity.
Authors: Duck-Chong C G , Gupta J M , Storey G N , Houghton C R 
Published: January 2020

Abstract
A micro-method has been devised for isolating a lung-derived membranous fraction from human amniotic fluid. The phospholipid content of this fraction, known as lamellar body phospholipid, provides an indication of fetal lung maturity (Ann. Clin. Biochem 16: 191, 1979). This method has now been applied to 479 samples of amniotic fluid from 330 pregnancies. The lecithin/sphingomyelin ratio has also been determined for each of the samples by the routine method currently in use in the hospitals providing the samples. Hyaline membrane disease was associated with a low concentration of lamellar body phospholipid (&lt; 35 mg/L) in all eight cases encountered in this study. In contrast, in 182 of the 185 cases where the lamellar body content of the amniotic fluid, collected within two days of delivery, exceeded 35 mg/L, the infants were free from serious respiratory problems. Data are presented which suggests that the lecithin/sphingomyelin ratio falsely indicated lung immaturity in many cases, amounting to 44% or more of all values indicating immaturity that were reported.
Carcinoembryonic antigen assayed by column chromatography on polyacrylamide gel.
Authors: Weissman E B 
Published: January 2020

Abstract
I evaluated a commercially available polyacrylamide column (Clinetics Corp.) for use in assaying for carcinoembryonic antigen. The procedure eliminates the need for dialysis and 50 samples, assayed in duplicate, may be completed in 5 h. In general, results by this technique are 1.0 microgram/L (range 0.5-2.0) lower than by the conventional dialysis method (r = 0.9876). Sensitivity approximates 0.5 microgram/L. Within-day precision for two pools of patients’ plasma (n = 10) was mean = 2.29 (SEM 0.05) microgram/L with CV = 6.55% and mean = 10.61 (SEM 0.10) microgram/L with CV = 2.92%, respectively; between-day precision (n = 6) was mean = 3.90 (SEM 0.16) microgram/L with CV = 10.0% and mean = 10.1 (SEM 0.37) microgram/L, CV = 8.91%, respectively. The precentage analytical recovery of added carcinoembryonic antigen was about 80% at concentrations of approximately 8 and 12 microgram/L, 73% at 18 microgram/L.
The coefficient of analysis, a new figure of merit for laboratory performance.
Authors: Louderback A L , Szatkowski P R 
Published: January 2020

Abstract
A simple statistic has been developed to determine a figure of merit for overall laboratory performance. This simple statistic, the coefficient of analysis, relates for the first time both the imprecision and the inaccuracy of a laboratory analysis to a single value that clinical chemists will easily understand. In the derivation of the coefficient of analysis, we also define two secondary statistics: the coefficient of bias, which is mathematically similar to the CV and represents the inaccuracy of an analysis, and the coefficient of accuracy, which is mathematically represented as 100 minus the coefficient of bias and is a measure of the accuracy of the analysis.
Influence of Posture on Free Calcium and Related Variables
Authors: Renoe Brian W , McDonald Jay M , Ladenson Jack H 
Published: January 2020

Abstract
Vol. 25
p 1766: Second paragraph, line four, the reference numbers cited should be (5-11); numbers of all subsequent citations above 10 in text should be increased by one, to correspond with the list of references.
p 1828: In Figure 2, the label on the ordinate is not clear. It reads “counts/10 s × 10−3.”
p 1930: Under “Determination of Concentrations in Human Plasma,” the injection of dihydroergotamine should be 0.5 mL of a 1 g/L solution.
p 1931: Nine to 12 determinations of binding in the absence of nonradioactive standard were also used to construct the standard curves.
p 1932: In the paragraph preceding Results and in the caption to Figure 3, the amount of compound 2 is 0.5 mg, not 1 mg.
p 2020: In the preparation of phosphate buffer, the second sentence should read: “Dissolve 2.84 g of sodium diphosphate in 100 mL of de-ionized water (solution 2).”
p 2021: In the section on extraction of serum under Procedures, the 10 µL of internal standard and 200 µL of sample should be added to 200 µL of phosphate buffer.
Vol. 26
p99: In the caption for Figure 3A, read “r = 0.99,” not “r = 0.09.”
p. 176: The sample volume referred to in the fourth paragraph of column three should be 0.15 µL, not “150 mL.”
p 193: Add to reference list:
8. Goutte-Coussieu, C., Habrioux, G., Eichenberger, D., and Jayle, M. F., Rapid fluorometry of estrogens in nonpregnancy urine, with use of chloroform extraction and purification by anion-exchange chromatography. Clin. Chem. 25, 230 (1979).
9. Jarrige, P., Purification et propriétés des sulfatases du suc d’Helix pomatia. Bull. Soc. Chim. Biol. (Paris) 7-8,761 (1963).
10. Ittrich, G., Untersuchungen über Extraktion des roten Kober-Farbstoffs durch organische Lösungsmittel zur Ostrogenbestimmung im Harn. Acta Endocrinol. (Copenhagen) 35, 34 (1960).
11. Adessi, G., Lallier, J. C., Goutte-Coussieu, C., and Jayle, M. F., Méthode de dosage automatique par spectrofluorimétrie des estrogénes urinaires au cours et en dehors de la grossesse. Ann. Biol. Clin. 37, 89 (1979).
12. Schöller, R., Contrôle de Qualité en Hormonologie. I.-Stéroides Urinaires. Editions Sepe, Paris-Fresnes, 1976, p 51.
p. 354: In Table 1, last line, columns 2 and 4, substitute “0.12” for “0.16.”
Measurement of tricyclic antidepressants. Part II. Applications of methodology.
Authors: Scoggins B A , Maguire K P , Norman T R , Burrows G D 
Published: January 2020

Abstract
This review, together with Part 1 (Clin. Chem. 26: 5-17, 1980), summarizes progress in measurement of tricyclic antidepressants in biological fluids and the application of the methodology to clinical practice. For many of the older drugs and for all of the new-generation antidepressants, further studies are required to delineate the precise relationship between plasma concentration and clinical response in well-defined diagnostic groups. For new drugs, rigorous evaluation of a method of measurement is required before it is applied to clinical studies. Assessment of drug interactions, inter-patient variability in plasma concentrations, and determination of the plasma concentrations required for therapeutic response all depend almost entirely on the quality of the assay methodology.
Improved serum-initiated aspartate aminotransferase assay by inhibition of lactate dehydrogenase with oxamate.
Authors: Lustig V , Redman L W 
Published: January 2020

Abstract
We describe a serum-inititated aspartate aminotransferase (EC 2.6.1.1) assay that obviates the need for added lactate dehydrogenase (EC 1.1.1.27) in the reagent system. Interference from the oxidation of NADH by endogeneous lactate dehydrogenase is eliminated by adding sodium oxamate, a competitive inhibitor of the enzyme. The advantages of oxamate inhibition over lactate dehydrogenase addition are a shorter preincubation period, an increase in the linear range from less than 600 to more than 1400 U/L, no interference from above-normal concentrations of ketoacids, and elimination of bias between serum-initiated and the standard oxoglutarate-initiated assays for aspartate aminotransferase.
Serum gastrins in Zollinger-Ellison syndrome: identification of localized disease.
Authors: Johnson J A , Fabri P J , Lott J A 
Published: January 2020

Abstract
We determined the relative concentrations of gastrin molecular species in serum samples from 21 patients with Zollinger-Ellison syndrome with localized gastrinoma (n = 11) or gastrinoma with hepatic metastases (n = 10). Gastrin molecular species were separated by gel-filtration chromatography and quantitated by radioimmunoassay with a gastrin antiserum produced in our laboratory. The percentage gastrin-17 of the total gastrin in the two groups differed significantly (nonparametric Wilcoxon rank test; p less than 0.01). Patients with the Zollinger-Ellison syndrome with apparently localized gastrinoma had a lower percentage of G- 17 (7.6%, SEM 1.6%) than did patients with gastrinoma with hepatic metastases (31.1%, SEM 6.1%). This procedure may be useful in the early classification of tumors in patients with Zollinger-Ellison syndrome.
DNA nucleotidylexotransferase of normal persons and leukemic patients.
Authors: Yasmineh W G , Smith B M , Bloomfield C D 
Published: January 2020

Abstract
We describe a relatively simple and rapid assay for DNA nucleotidylexotransferase (EC 2.7.7.31) activity in normal lymphocytes and leukemic cells from blood and (or) bone marrow of patients with various types of leukemia. We followed the method of Beutler and Kuhl (Am. J. Clin. Pathol. 70: 733, 1978) but separated the product of the reaction by precipitation on filter-paper disks instead of by centrifugation. Normal lymphocytes had a mean activity of 13.5 (SD = 9.21; range 3 to 35) pU/10(8) cells. Leukemic cells from the peripheral blood of patients with acute myelogenous leukemia had a mean activity slightly greater than normal (48 pU/10(8) cells); those from patients with acute lymphoblastic leukemia had a mean activity of 863 pU/10(8) cells, or 62-fold the normal mean. Similarly, cells from patients with chronic myelogenous leukemia in acute phase had a normal activity when the cell proliferation was myelogenous, but much higher activities when the cell proliferation was lymphoblastic. Cells from patients with chronic lymphocytic leukemia had normal activity. In leukemic patients, approximately similar results were obtained with cells isolated from bone marrow.
Applicability of various quality-control sera to assay of high-density lipoprotein cholesterol.
Authors: Bullock D G , Carter T J , Hughes S V 
Published: January 2020

Abstract
Effective internal quality control and external quality assessment of high-density lipoprotein cholesterol assay is made difficult by analyte instability, and the suitability of quality-control sera for this purpose has not been studied. We have therefore investigated the properties of 25 different control sera from 15 suppliers by estimating within-batch precision for the two precipitation procedures used most widely (phosphotungstate/Mg2+ and heparin/Mn2+ with enzymic measurement of cholesterol. Some sera had properties similar to those of fresh human serum, but others demonstrated poor precision for one or both procedures or contained apparent high-density lipoprotein cholesterol in unphysiological concentrations. A study of six sera indicated that between-batch precision was consistent with the within-batch findings. We found that eight of the 25 batches of quality-control serum we investigated may be used for internal quality control and external quality assessment of high-density lipoprotein cholesterol assay.
Liquid-chromatographic assay of urinary 5-hydroxy-3-indoleacetic acid, with electrochemical detection.
Authors: Shihabi Z K , Scaro J 
Published: January 2020

Abstract
After extraction with two organic solvent mixtures, urinary 5-hydroxy-3-indoleacetic acid can be assayed by "high-performance" liquid chromatography on a reversed-phase column, with electrochemical detection. Compared to the nitrosonaphthol method (J. Biol. Chem. 216: 499, 1955), this method is more specific for detection of patients with carcinoid tumors.
Improvements in hemoglobin AI determination by rapid cation-exchange chromatography.
Authors: Rand P G , Nelson C 
Published: January 2020

Abstract
The accuracy of many convenient methods for determining the proportion of hemoglobin AI to total hemoglobin by ion-exchange chromatography is in question because those methods have not been evaluated against a reference method. In addition, several if not all of these tests are influenced by laboratory temperature. We modified the chromatographic conditions usually used, to arrive at a method that gives results that agree well with those by the Trivelli method (N. Engl. J. Med. 284, 353, 1971) and is less influenced by ambient temperature than are results obtained with the commercially available Helena and Isolab kits. We accomplished this by lowering the pH of the fast-hemoglobin eluting buffer, with a corresponding adjustment in the ionic strength. We also use a larger elution volume, which assures more nearly complete elution of the hemoglobin A1 fraction. The final method (y) agreed being y = 0.98x + 0.63 r2 = 0.887. Average results from the Helena and Isolab methods were lower than with the reference method by 1.58 and 3.03% hemoglobin A1, respectively.
Composition of serum very-low-density and high-density lipoproteins in diabetes.
Authors: Gabor J , Spain M , Kalant N 
Published: January 2020

Abstract
We examined the cholesterol/protein ratio and the apoprotein composition of serum lipoproteins in a randomly selected population of maturity-onset diabetics and in a group of nondiabetics of similar age. We found no differences in cholesterol distribution between the groups as a whole, but diabetics with above-normal low-density lipoproteins (LDL) had decreased concentrations of high-density lipoprotein (HDL) cholesterol. In the diabetics as a whole, there was an increase in the cholesterol/protein ratio in HDL, a negative correlation between the amounts of LDL cholesterol and HDL cholesterol, an increase in the proportion of apolipoprotein C in very-low-density lipoprotein (VLDL), and a decrease in the proportion of the apolipoprotein AI component of HDL. In diabetic subjects with increased VLDL, there was an increase in the relative amount of apolipoprotein CIII, and a consequent decrease in the ratio of apolipoprotein CII/apolipoprotein CIII in the VLDL. In both diabetic and control subjects, apolipoprotein E and cholesterol content of VLDL were linearly related.
Enzymic determination of 3 alpha-, 7 alpha-, and 12 alpha-hydroxyl groups of fecal bile salts.
Authors: Crowell M J , Macdonald I A 
Published: January 2020

Abstract
We used microbial 3 alpha, 7 alpha-, and 12 alpha-hydroxysteroid dehydrogenases to quantify 3 alpha-, 7 alpha-, and 12 alpha-hydroxyl groups in human feces. Samples collected over a 48-h period were lyophilized, extracted, and reconstituted by a modification of the method of DeWael et al. (clin. Chim. Acta 79: 465--470, 1977), then quantified enzymically by use of three group-specific hydroxysteroid dehydrogenase preparations. Total values for the three hydroxyl groups are given for 18 healthy humans. The ratio of 3 alpha-OH groups/7 alpha-OH groups/12 alpha-OH groups was 34.4 (SD 5.9)/25.2 (SD 6.4)/40.4 (SD 7.7) for the 18 samples.