bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid radiometric assay used to assess lactoferrin in granulocytes.
Authors: Freeman K L , Anderson D C , Hughes B , Buffone G J 
Published: January 2020

Abstract
We describe a rapid, precise, and sensitive radiometric assay for human lactoferrin. In this typical "sandwich"-type assay, anti-human lactoferrin is adsorbed onto a polystyrene sphere and bound lactoferrin is detected by the subsequent binding of 125I-labeled anti-human lactoferrin. The assay is accurate for lactoferrin concentrations of 5 to 1500 micrograms/L and takes about 2.5 h to complete. The within-assay and interassay variations (CV) are 5% and 13%, respectively. Neither lysozyme nor heparin, substances that form complexes with lactoferrin, interfered with lactoferrin measurement by this method. The assay has been applied to the measurement of lactoferrin in polymorphonuclear leukocytes of both healthy adults and neonates. We found significantly (p less than 0.001) less lactoferrin in the latter, an abnormality that may be related to known functional deficits of polymorphonuclear leukocytes during the newborn period.
Choriogonadotropin measured with the Tandem-E immunoenzymetric assay system.
Authors: Bock J L , Furgiuele J , Segen J C 
Published: January 2020

Abstract
We evaluated the Hybritech Tandem-E procedure for quantifying choriogonadotropin (hCG) in human serum. In this "sandwich"-type assay, two monoclonal antibodies directed against different regions of the hCG molecule are used, one coated on a plastic bead, the second conjugated to alkaline phosphatase. The assay can detect as little as 1.0 int. unit of the hormone per liter, shows a linear response up to at least 200 int. units/L, and has good precision. By prolonging the incubations for formation of the sandwich and for substrate hydrolysis, one can achieve higher sensitivity at the expense of a narrower linear range. Correlation with a conventional radioimmunoassay for the beta subunit of hCG was generally excellent, but in one instance the Tandem-E gave an apparently false positive result.
Molar absorptivity and the blank correction factor.
Authors: Kroll M H , Elin R J 
Published: January 2020

Abstract
In photometry, where both the product formed and one or several reactants absorb light at the same wavelength, the absorbance of the "blank" of the sample at the end of the reaction may be less than that measured at the beginning of the reaction, because of consumption of reactant(s). The blank correction factor for the determined result with one light-absorbing reagent is epsilon P / (epsilon P - epsilon R), where epsilon R and epsilon P are the molar absorptivities of the reagent and the product, respectively. We derived a factor for the case when more than one reagent absorbs light at the same wavelength as the measured product. This factor is independent of the concentration of reagent(s) and can correct the determined result or absorbance for the consumption of light-absorbing reagent(s) during the reaction.
Immunoenzymetric assay for creatine kinase MB with subunit-specific monoclonal antibodies compared with an immunochemical method and electrophoresis.
Authors: Chan D W , Taylor E , Frye R , Blitzer R L 
Published: January 2020

Abstract
Results of an immunoenzymetric assay (TANDEM-E CKMB) for creatine kinase (CK; EC 2.7.3.2) MB isoenzyme, in which subunit-specific monoclonal antibodies are used, were compared with those by an immunochemical method (Isomune-CK) and electrophoresis (Corning agarose gel). The study involved 200 patients; greater than 500 samples were analyzed by all three methods. The analytical performances were acceptable. Between-method correlation coefficients ranged from 0.881 to 0.975. Two reference intervals were established for the immunoassays: 0-4 micrograms/L (TANDEM) and 0-4 U/L (Isomune) for "normal" patients; 0-9 micrograms/L (TANDEM) and 0-14 U/L (Isomune) for noninfarct patients. Agreement with respect to increased CK-MB as defined by the reference intervals for the noninfarct patient was 96% between TANDEM and electrophoresis, 90% between Isomune and electrophoresis. All three methods are acceptable for use in determining CK-MB, but the overall diagnostic efficiencies for the mass or activity concentration of the isoenzyme and for its proportion of total CK activity, based on the predictive value model, are 92% (electrophoresis, 0-7 U/L), 90% (electrophoresis, 0-4%), 92% (TANDEM, 0-9 micrograms/L), 88% (TANDEM, 0-3% index), 88% (Isomune, 0-14 U/L), and 83% (Isomune, 0-4%). All three methods can detect CK-MB in serum, but its presence is not necessarily diagnostic of acute infarct. We recommend using the actual concentration of CK-MB to evaluate patients with suspected acute myocardial infarct, and the percentage of CK-MB when total CK is very high.
Total cholinesterase in plasma: biological variations and reference limits.
Authors: Lepage L , Schiele F , Gueguen R , Siest G 
Published: January 2020

Abstract
Factors affecting biological variation in total cholinesterase activity in plasma were studied in a population of 3372 apparently healthy subjects at least four years old. Determination of the dibucaine number, after inhibition of the activity by dibucaine, made it possible to specify the contributions of genetic and physiological characteristics to variations in the total activities by using a statistical method of segmentation. The main factors modifying plasma cholinesterase activity in males are genetic status (dibucaine number) and degree of overweight (subscapular skinfold). In females, hormonal status (puberty or menopause), genetic status (dibucaine number), and the use of oral contraceptives are the factors mainly responsible for the variations of plasma cholinesterase activity. These data allow us to propose reference limits for total plasma cholinesterase.
Head-space gas-chromatographic determination of 3-hydroxybutyrate in plasma after enzymic reactions, and the relationship among the three ketone bodies.
Authors: Kimura M , Kobayashi K , Matsuoka A , Hayashi K , Kimura Y 
Published: January 2020

Abstract
In this sensitive, reproducible method for determination of D-3-hydroxybutyrate (3-OHB) in plasma, it is converted to acetone by use of 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30)/lactate dehydrogenase (EC 1.1.1.27) coupled with acetoacetate decarboxylase (EC 4.1.1.4). The resulting acetone is detected by head-space gas chromatography. The lowest concentration of 3-OHB detectable in plasma was 2 mumol/L. The calibration curve showed a linear relationship for 3-OHB concentration from 0 to 5 mmol/L (r = 0.999). Analytical recovery of 3-OHB (50 mumol/L) was 97.9 (SD 3.8)%. The method was developed for determination of the three ketone bodies in plasma. The ratio of acetone to acetoacetate was not significantly different (p greater than 0.2) between normals (n = 31) and diabetics (n = 86). In normal subjects, the ratio of 3-OHB to acetoacetate was 1.20 (SD 0.44). In diabetic patients, the ratio correlated with the logarithm of the total ketone body concentration (r = 0.828).
K, Ca, Mg, and Zn in platelets, as determined by atomic absorption spectrometry with use of a sealed decomposition bomb and discrete nebulization.
Authors: Makino T 
Published: January 2020

Abstract
In this new method for precise and accurate determination of K, Ca, Mg, and Zn in platelets, small amounts of platelets, prepared by differential centrifugation and cell washing, are decomposed in a homemade mini-vessel, a sealed Teflon bomb. The metal ions in the decomposed sample are measured by atomic absorption spectrometry with discrete nebulization. Overall, CVs ranged from 0.8 to 4.8%. We investigated sex-related differences (none were found) and intra-individual variations.
Factors affecting the binding of disopyramide to serum proteins.
Authors: Shaw L M , Altman R , Thompson B C , Fields L 
Published: January 2020

Abstract
We investigated the influence of the following factors on the binding of disopyramide to serum proteins: method of drug quantification [enzyme immunoassay (EMIT) compared with liquid chromatography (HPLC)], separation technique (ultrafiltration vs equilibrium dialysis), temperature, pH, and total concentration of disopyramide. EMIT and HPLC measurements of disopyramide in ultrafiltrates prepared from 50 sera agreed well: EMIT = 1.046 HPLC + 0.042, (r = 0.928, SEE = 0.04 mg/L). Free disopyramide concentrations in ultrafiltrates of dialyzed sera were similar to those measured in the corresponding dialysates by the EMIT method for 30 patients' sera: ultrafiltrate of serum retentate = 1.053 dialysate + 0.042. Concentrations of free [14C]disopyramide were little affected by temperature. The concentration of free disopyramide decreased as the pH was increased from 7.0 to 7.8. The concentration of free disopyramide, as determined by ultrafiltration, is strongly and directly related to total drug concentration. In the sera of 50 cardiac patients receiving chronic therapy with disopyramide and with total disopyramide concentrations of 0.5 to 5.8 mg/L, the proportion of free disopyramide ranged from 16 to 54%.
Rapid assessment of albumin concentration by immunoturbidimetry.
Authors: Biou D , Thérond P , Israël A , Demelier J F 
Published: January 2020

Abstract
The dye-binding methods involving bromcresol green and bromcresol purple may seriously overestimate albumin in serum that has a below-normal albumin/globulin ratio, particularly in nephrotic syndrome hypoalbuminemia. To overcome this problem, we developed a new immunoturbidimetric method for albumin with use of a centrifugal analyzer. Results by this method (y) and by radial immunodiffusion (x) agreed well and yielded the regression equation: y = 0.91x + 1.33 (n = 40, r = 0.96). Compared with laser immunonephelometry, our method is easier and faster (15 min for the overall determination). Thus, the proposed immunoturbidimetric method is particularly suitable for the rapid indirect assessment of oncotic pressure and indirectly for monitoring intravascular body fluids.
Improved column-chromatographic isolation of glycosylated hemoglobin S.
Authors: Cirotto C , Allegrucci M , Cartechini M G , Compagnucci P , Santeusanio F , Bolli G 
Published: January 2020

Abstract
We investigated glycosylated hemoglobin S by means of chromatography on Bio-Rex 70. The selected elution conditions were similar to those described by Trivelli et al. (N Engl J Med 284: 353-357, 1971), except for modified ionic strength and accurate temperature control. This enabled us to isolate a minor hemoglobin fraction whose properties, as determined by chromatography, electrophoresis, and two-dimensional maps of its tryptic peptides, were typical of a hemoglobin S tetramer with blocked N-terminal residues of the beta subunits. The colorimetric test indicated this to be a glycosylated hemoglobin. This procedure is notably improved over previous chromatographic techniques for isolating glycosylated hemoglobin S. Moreover, it can be easily used in any laboratories where Trivelli's method is routinely in use.
Quality control of reflectometric determinations of glucose in dried blood spots on filter paper.
Authors: von Schenck H , Lönnström L , Engström M 
Published: January 2020

Abstract
We evaluated the effect of sampling of capillary blood on filter paper on the later analysis for glucose. We found the method simple and reliable. Determination at the central laboratory of glucose in blood collected onto filter paper and comparison of the results with those obtained with test strips read in reflectometers at outpatient units is easy. Collecting duplicate samples on filter paper facilitates quality control by avoiding the complications that arise from using quality-control solutions that are not directly comparable with fresh blood, and it avoids the disturbances of test strip chemistry attributable to the glycolysis inhibitors added to blood samples intended for quality control.
Thyroid-function assessment by use of enzyme immunoassays.
Authors: Proença M T , de Moura L S 
Published: January 2020

Abstract
We used an enzyme immunoassay to determine the normal reference intervals for thyroxin, triiodothyronine, and thyrotropin in groups of children, ranging from newborns to 15-year-olds. Results compared well with those by radioimmunoassay. There were no substantial differences between plasma and serum samples for thyroxin and triiodothyronine, but thyrotropin concentrations differed significantly (p less than 0.05, n = 20 each).
Applications of recombinant DNA to pathologic diagnosis.
Authors: Sauls C D , Caskey C T 
Published: January 2020

Abstract
Recombinant DNA techniques are contributing to the understanding of the pathogeneses of genetic, neoplastic, and viral diseases, and are used in the diagnosis of certain genetic and viral diseases. Such techniques will have wider application in the future and will play an increasing role in the clinical laboratory. The technology of this field rests upon the cleavage of DNA by certain enzymes, restriction endonucleases, and upon the ability to locate specific sequences of nucleotides in a cleaved DNA sample by using known fragments of DNA ("probes") labeled with radioisotopes or biotin. To produce useful probes, one "clones" multiple copies of the same DNA fragment in bacteria. The use of DNA probes in the clinical laboratory is valuable in antenatal diagnosis, genetic counseling, and post-natal diagnosis of genetic diseases, especially hematologic diseases and inborn errors of metabolism. DNA probes can also be used to detect viral genetic material in clinical specimens.
Radioimmunoassay for detecting hepatitis B core antigen in serum from patients with chronic hepatitis B infection.
Authors: Quiroga J A , González O , Carreño V , Mora I , Porres J C , Gutiez J , Hernández-Guío C 
Published: January 2020

Abstract
The core antigen component of hepatitis B virus (HBV), HBcAg, may be used as a marker of viral replication. We describe a radioimmunoassay for HBcAg in serum, and compare results with those by other similar methods. Samples are centrifuged over a sucrose gradient containing 2-mercaptoethanol, and the resulting pellets are resuspended in a nonionic detergent solution. After a bead coated with anti-HBcAg is incubated with this suspension, 125I-labeled anti-HBcAg is added, and is also bound by the antigen. The specificity of the method was verified by blocking with purified IgG antibodies to HBcAg. When we tested by this method for HBcAg in sera from 60 patients with chronic HBV infection, all those with circulating HBV-DNA polymerase tested positive for HBcAg. All sera from HBV-negative controls showed no detectable HBcAg. The correlation between the presence of HBcAg and HBV-DNA polymerase was significant (r = 0.715, p less than 0.001). Samples can be tested more quickly and easily with this method, and its sensitivity compares well with that of other similar methods.
Immunoenzymometric assay and radioimmunoassay measure different populations of antibody against human acetylcholine receptor.
Authors: Hinman C L , Kellogg C M , Ernstoff R M , Rauch H C , Hudson R A 
Published: January 2020

Abstract
We used a "sandwich"-type immunoenzymometric assay (IEMA) and a radioimmunoassay (RIA) to measure antibody against the human nicotinic acetylcholine receptor in serum from individuals with myasthenia gravis, with markedly different results for certain specimens, as measured by the two techniques. In some cases, antibody concentrations were high by RIA but low by IEMA; in others, the reverse was found. Such differences persisted through 30 months after thymectomy. An investigation of potential causes of this disparity suggests that high IEMA measurements reflect specific anti-receptor antibody and are not artifactual. The IEMA is recommended as an adjunct to the RIA because some patients with myasthenia gravis who have low concentrations of anti-receptor antibodies as measured by RIA have significantly above-normal concentrations of anti-receptor antibodies as measured by IEMA.
A monoclonal-antibody-based immunoradiometric assay for apoprotein B in low-density lipoprotein.
Authors: Slater H R , Tindle R W , Packard C J , Shepherd J 
Published: January 2020

Abstract
Five different mouse monoclonal antibodies were raised against apoprotein B, the major protein in human low-density lipoproteins (LDL). Competitive binding studies suggested that these antibodies recognized four different epitopes on the lipoprotein particle. All antibodies bound to very-low-density and intermediate-density lipoproteins, which are the metabolic precursors of LDL and also contain apoprotein B. One antibody (P1C1) displayed a relative specificity for apoprotein B in LDL as compared with that in very-low-density lipoprotein and was used as a radiolabeled first antibody in an immunoradiometric assay for this lipoprotein. Measurements, either on isolated LDL or directly on plasma samples, demonstrated that this assay provides a rapid and precise method of quantification.
Benzethonium chloride method for proteins adapted to centrifugal analysis.
Authors: McDowell T L 
Published: January 2020

Abstract
A benzethonium chloride method for measuring protein concentrations in several types of body fluids has been adapted to the Cobas Bio centrifugal analyzer. The ability of this analyzer to add two reagents stepwise, measuring absorbances after each addition, is essential for proper blanking of urine specimens. The method has excellent curve stability and precision and yields results that correlate well with those of four other protein methods.
On the natural history of hypergastrinemia.
Authors: Lindstedt G , Runsteen D , Lundberg P A , Bengtsson C , Lapidus L , Nyström E , Kilander A F 
Published: January 2020

Abstract
We determined total gastrin and pepsinogen I in frozen serum samples from 175 overnight-fasted women 54 years old, and from 81 overnight-fasted women 60 years old, who took part in a population study in 1968-69. We also assayed samples from some of these women, who participated in clinical follow-up studies in 1974-75 and 1980-81: all of the women in the initial group whose serum gastrin concentration exceeded the 85th centile value and, as a reference group, a randomized subsample of women whose initial serum gastrin concentration was less than the 80th centile. Samples with total gastrin concentration greater than 400 ng/L were also assayed for gastrin-17 and gastrin-34. We found that: a pronounced increase of serum gastrin persisted throughout the study period for most of these postmenopausal women, indicating that conversion of type A gastritis (antrum-sparing) to pan-gastritis is uncommon; unexplained high concentrations of pepsinogen I in relation to the reference interval for young and middle-aged adults, as well as in relation to serum gastrin, were common; and the gastrin-17/gastrin-34 ratio is not correlated with the outcome of pronounced hypergastrinemia.
Rapid procedure for fecal porphyrin assay.
Authors: Lockwood W H , Poulos V , Rossi E , Curnow D H 
Published: January 2020

Abstract
Hydrochloric acid extraction of feces in the presence of ether yields an extract suitable for spectrophotometric estimation of total porphyrin and for further separation by "high-performance" liquid chromatography (HPLC) or thin-layer chromatography. A total porphyrin reference interval of less than 200 nmol/g dry weight of feces was established from data on 106 normal subjects on an unrestricted diet. Total fecal porphyrin values in 11 porphyria cutanea tarda patients were considerably higher than given by the widely used Rimington method (respective means, 652 and 239 nmol/g dry weight). Our HPLC method for separation of porphyrin methyl esters on a silica column, with quantification by fluorescence, is described. HPLC separations performed on 23 porphyria cutanea tarda patients gave the following mean proportions of total fecal porphyrins: dicarboxylics 21%, coproporphyrin 9%, isocoproporphyrins 28%, pentacarboxylporphyrin 9%, hexacarboxylporphyrin 11%, heptacarboxylporphyrin 18%, and uroporphyrin 4%.
Rate-nephelometric determination of fibronectin in plasma.
Authors: van Helden W C , Kok-Verspuy A , Harff G A , van Kamp G J 
Published: January 2020

Abstract
We describe a kinetic immunonephelometric method for the determination of fibronectin in human plasma, used with the Beckman ICS rate nephelometer. The method is rapid and cost-effective. Two commercially available controls stated by the manufacturer to contain 200 and 295 mg/L were found to contain 198 and 290 mg/L, respectively. Mean analytical recovery was 104%. Within-run precision (CV) for normal samples was 3.8%, between-day precision 5.1%. For samples containing subnormal concentrations of fibronectin, these figures were 3.8% and 6.7%, respectively. Results by the method described here agreed and correlated well with those by a commercially available turbidimetric assay. With appropriately diluted samples, the range of measurement is 40 to 1000 mg/L. Normal values for women and men were 286 (SD 84) and 340 (SD 55) mg/L, respectively, in good agreement with values published by others.
Incubation with neuraminidase and affinity electrophoresis with wheat-germ lectin compared for separating and quantifying alkaline phosphatase isoenzymes in plasma.
Authors: Rosalki S B , Foo A Y 
Published: January 2020

Abstract
Of 98 patients' specimens examined for alkaline phosphatase (EC 3.1.3.1) isoenzymes by electrophoresis on cellulose acetate membrane after incubation with neuraminidase, 50 showed only a single liver or bone isoenzyme staining band; in 15 of these, the tissue origin of the fraction could not be accurately identified from its electrophoretic location. In the remaining 48 specimens, both liver and bone fractions were identifiable, but in only 25 of these was the electrophoretic resolution sufficient to yield separate peaks on densitometry. In contrast, both liver and bone alkaline phosphatase isoenzymes were identified in 95 of the 98 specimens by affinity electrophoresis involving wheat-germ lectin, the detection of both fractions being in agreement with the results of sequential heat inactivation. The tissue origin of the enzyme bands was readily ascertainable from their consistent electrophoretic location in this medium, and in 89 of the specimens the isoenzyme fractions could be resolved into separate peaks on densitometry. We conclude that resolution of liver and bone alkaline phosphatase by incubation with neuraminidase followed by cellulose acetate electrophoresis is greatly inferior to that obtained by wheat-germ lectin affinity electrophoresis.
Improved preparation of cholesterol calibration and control sera.
Authors: Terlingen J B , van Dreumel H J , van Heiningen A , Boerma G J , Koedam J C 
Published: January 2020

Abstract
We prepared several serum batches with various cholesterol concentrations, to be used as calibrators and controls in a proficiency testing program of an organization in The Netherlands that is in charge of the standardization of cholesterol determinations for epidemiological purposes. The sera were of human origin, to avoid abnormal matrix effects. To decrease the cholesterol content in some samples, we adsorbed them onto colloidal silicic acid. To increase it, we added lipoproteins that had been precipitated from human serum with heparin and calcium ions. The precipitation method we used allowed us to dilute the serum as little as possible and to keep the final concentrations of calcium and heparin as low as possible, while maintaining a high cholesterol content. By mixing these sera having high and low cholesterol concentrations, we could prepare batches with any desired concentration. The stabilities of these sera were excellent. We used the sera to calibrate enzymic determinations of cholesterol.