bluuebunny/crossref_metadata_2025_split huggingface dataset:
A cellulose acetate electrophoretic procedure evaluated for quantitation of high-density lipoprotein cholesterol.
Authors: Schifman R B , Brumbaugh P F , Grover D , Finley P R , Harrow E J 
Published: January 2020

Abstract
We evaluated the performance of a commercially available cellulose acetate electrophoretic method for quantitating high-density lipoprotein cholesterol (I) in serum by comparing it to a method involving precipitation with dextran sulfate-500/Mg2+. In both methods, enzymic reagents are used for cholesterol measurement. For electrophoretic measurement of I the mean intramembrane CV ws 4.1% (at 220 to 360 mg/L) and the intermembrane CV ranged from 12.2 to 21.0% (at 220 to 880 mg/L). Interassay precision was significantly better for the precipitation method (CV = 3.9% at 390 mg/L). The electrophoretic procedure demonstrated significant measurement bias, both at high and low I concentrations. However, low-density lipoprotein cholesterol, measured electrophoretically correlated well with its calculated concentrations obtained by the precipitation method. Measurement of I by this electrophoretic procedure did not achieve the accuracy and reproducibility that have been demonstrated for precipitation methods and that are necessary for reliable clinical interpretation of results for I.
Homogeneous substrate-labeled fluorescent immunoassay for theophylline in serum.
Authors: Li T M , Benovic J L , Buckler R T , Burd J F 
Published: January 2020

Abstract
A substrate-labeled fluorescent immunoassay for theophylline in serum is described. 8-(3-Aminopropyl)-theophylline is covalently attached to a fluorogenic enzyme substrate, 7-beta-galactosylcoumarin-3-carboxylic acid. Hydrolysis of this theophylline-labeled substrate by beta-galactosidase yields a fluorescent product. When antibody to theophylline interacts with this substrate, the resulting complex is inactive as an enzyme substrate. For measuring theophylline, competitive protein-binding reactions are set up, with the theophylline in the sample competing with the substrate for the antibody-binding sites. The substrate not bound to antibody is hydrolyzed by beta-galactosidase, producing fluorescence that is proportional to the theophylline concentration. Results for theophylline determined by this method in clinical samples of serum correlated well (r &gt; 0.96) with results obtained by gas-chromatographic or enzyme immunoassay procedures. The within-run CV for three control samples ranged from 1.1 to 2.8%, the between-run CB from 2.3 to 4.5%.
Double-antibody radioimmunoassay of thyroid microsomal antibody in serum.
Authors: Kung V T , Weber P M , dos Remedios L V 
Published: January 2020

Abstract
We describe a double-antibody radioimmunoassay for antimicrosomal antibodies in serum. Antigen in centrifuged pellets of microsome is solubilized by treatment with sodium deoxycholate solution and radiolabeled (125I] by the Chloramine T method. A 10-microL aliquot of human serum or antimicrosomal antibody standard is incubated overnight at room temperature with 125I-labeled microsome. Bound radiolabeled microsome is separated by precipitation with goat antihuman IgG antiserum. The percentage of 125I-labeled microsome bound by each serum is calculated, and its concentration of antimicrosomal antibody interpolated from a standard curve. The prevalence of abnormal antimicrosomal antibody was 16% in a self-referred asymptomatic or not acutely ill group of patients having a periodic multiphasic health examination. Values for patients with certain thyroid diseases generally agreed with other published data. We conclude that our assay is sensitive, precise, and accurate, and is more efficient for routine measurement of antimicrosomal antibody than the currently used solid-phase radioimmunoassay.
Lectins used to prepare serum free of glycoprotein hormones for use as a matrix in radioimmunoassay.
Authors: Stuart M C , Ellis S , Gowlland L , Tuff S 
Published: January 2020

Abstract
Hormone-free serum is required for use as a matrix for standards in the radioimmunoassay of hormones. The glycoprotein hormones are difficult to remove from serum by conventional techniques. We exploited the specific binding of carbohydrates by lectins to extract glycoprotein hormones from human serum. Passing serum over Concanavalin A Sepharose efficiently removed lutropin and the beta subunit of choriogonadotropin. Wheat-Germ Lectin Sepharose completely removed these, and also follitropin and thyrotropin. The latter treatment is shown to provide a suitable matrix for standards in radioimmunoassays of the four hormones.
Acetylcholinesterase and fetal malformations: modified qualitative technique for diagnosis of neural tube defects.
Authors: Haddow J E , Morin M E , Holman M S , Miller W A 
Published: January 2020

Abstract
A single-blind study involving amniotic-fluid samples from 214 pregnancies of known outcome confirms that an electrophoretically distinct isoenzyme of acetylcholinesterase is associated with fetal open neural tube defects. Furthermore, only one of 13 amniotic-fluid samples with false-positive results for alpha-fetoprotein showed the characteristic isoenzyme, indicating that qualitative acetylcholinesterase assessment can decrease the proportion of false positives from the alpha-fetoprotein assay. We have also identified this characteristic isoenzyme in amniotic fluids from pregnancies in which other serious fetal defects occurred. A detailed electrophoresis protocol for identifying this characteristic isoenzyme is described.
Sources of variation in the column-chromatographic determination of glycohemoglobin (HbA1).
Authors: Schellekens A P , Sanders G T , Thornton W , van Groenestein T 
Published: January 2020

Abstract
We studied the influence of many variables on the cation-exchange chromatographic determination of glycohemoglobin was minicolumns (HbA1) and with macrocolumns (HbA1a+b and HbA1c). Minicolumns are most sensitive to buffer composition. The best conditions are pH 6.78 and sodium, potassium, and phosphate concentrations of 54.8, and 36 mmol/L, respectively. In fact, there is no clear cut-off point for elution. A cyanide concentration of 1.5 mmol/L has no negative effects. For macrocolumns, the influence of temperature is demonstrated; 20 degrees C is optimal. A higher temperature caused results for HbA1 to be higher. For minicolumns, the temperature effect corresponds to 1% HbA1 per 1 degrees C, necessitating rigorous temperature control. The amount of sample applied also influences the results. Therefore a constant column load, chosen between 1.3 and 2.0 mg of Hb permilliliter of resin, is advised. Heparinized blood can be kept for three days at 4 degrees C; hemolyzed samples are best stored at -70 degrees C.
(omega-1)-Hydroxymonocarboxylic acids in urine of infants fed medium-chain triglycerides.
Authors: Shigematsu Y , Momoi T , Sudo M , Suzuki Y 
Published: January 2020

Abstract
Organic acids in the urine of infants fed a formula containing medium-chain triglycerides (octanoic acid 49% and decanoic acid 26% of total fatty acids) were determined by gas chromatography-mass spectrometry. We found a considerable amount of 5-hydroxyhexanoic acid and 7-hydroxyoctanoic acid, but no detectable 9-hydroxydecanoic acid, as well as a large amount of C6-C10-dicarboxylic acid. We believe that such acids are derived, via (omega-1)-hydroxylation, from medium-chain monocarboxylic acid or medium-chain acyl-CoA in the liver cell. The degree of (omega-1)-hydroxylation of medium-chain fatty acids relative to omega-hydroxylation apparently increases as the chain length of the fatty acids decreases.
Increased inactive creatine kinase B protein in the plasma of patients with malignancy.
Authors: Burnam M H , Barstis J L , Stern C S , Rose D M , Crouch M A , Haskell C M , Singh B N 
Published: January 2020

Abstract
Using a specific radioimmunoassay for enzymically inactive creatine kinase (EC 2.7.3.2) B protein (CK-Bi), we studied 139 patients with various malignancies. We found it to be increased in certain adenocarcinomas, including colorectal, lung, and prostate, as has also been reported for enzymically active CK-BB. Of 15 patients with leukemia or lymphomas with active disease, 12 also had increased values for CK-Bi in plasma. In these patients, concentrations of CK-Bi in plasma tended to correlate with disease activity, increasing with aggressive malignancy and decreasing on successful treatment. Thus, measurement of CK-Bi may constitute a sensitive means for detecting malignancy and, in certain subsets of patients, for monitoring therapeutic response.
Factors affecting enzyme-linked immunosorbent assay (ELISA) for insulin antibodies in serum.
Authors: Flynn S D , Keren D F , Torretti B , Dieterle R C , Grauds S 
Published: January 2020

Abstract
We have evaluated the factors affecting an enzyme-linked immunosorbent assay (ELISA) for circulating insulin antibodies. Dilutions of patients' sera were incubated in polystyrene tubes coated with procine insulin. The second incubation was with alkaline phosphatase-conjugated anti-human Fab. Each of these reactions was complete after 4 h. Specificity of the reaction for insulin antibodies was demonstrated by removal of anti-insulin activity after preincubation with insulin, but not with glucagon at similar concentrations. Sensitivity of the ELISA system, assessed by performing the reaction with affinity-column purified insulin antibodies, was 10 microgram of specific antibody per liter. Using this system, we examined sera from 22 patients who had been determined by radioimmunoassay to have insulin antibodies, and sera from 23 normal individuals. The ELISA results correlated reasonably well with those of RIA (r = +0.84). Besides detecting insulin antibodies in diabetic patients who are being treated with insulin, we use this ELISA test as a screening procedure to be certain insulin antibodies are not present when we use indirect immunofluorescence methods of fixed pancreatic substrate to detect islet-cell antibodies.
Measurement of "lamellar body phospholipid" in amniotic fluid as a method for assessing fetal lung maturity.
Authors: Duck-Chong C G , Henderson-Smart D J , Gupta J M , Hensley W J 
Published: January 2020

Abstract
A simple, rapid micro-method, suitable for use in a routine clinical laboratory, is described for isolating a surfactant fraction from 0.1 mL of human amniotic fluid and measuring its phospholipid content. We determined the phospholipid content of this fraction, referred to as "lamellar body phospholipid," in 451 samples of amniotic fluid collected within two days of delivery and related the data to the respiratory performance of the newborn in every case; 112 of the infants were delivered at 28-37 weeks gestation. The incidence of hyaline membrane disease was inversely related to the concentration of lamellar body phospholipid in the amniotic fluid. Eleven of 12 infants with lamellar body phospholipid values less than 25 mg/L and four of 44 infants with lamellar phospholipid values between 25 and 50 mg/L developed hyaline membrane disease or other serious respiratory problems possibly related to lung immaturity, whereas all of 395 infants with lamellar body phospholipid values of 50 mg/L or more were free from respiratory problems of this nature. The incidence of transient tachypnea was greatest when the lamellar body phospholipid value was between 25 and 50 mg/L, suggesting that this condition may be related to a degree of lung maturity.
A model for validation of radioimmunoassay kit reagents: measurement of follitropin and lutropin in blood and urine.
Authors: Santner S J , Santen R J , Kulin H E , Demers L M 
Published: January 2020

Abstract
We measured lutropin and follitropin in blood and urine with radioimmunoassay kits from Diagnostic Products Corporation and compared the results with those obtained by use of reagents from the National Institutes of Health (NIH) and the World Health Organization (WHO). The urine standard (second IRP-HMG) from WHO, the blood standard (LER-907) from NIH, and the commercial standards all effected similar displacement of trace material when the commercial gonadotropin kit reagents were used. Highly significant correlations were achieved for these hormones in blood or urine on comparing commercial and NIH/WHO reagents. Serial dilutions of urine samples produced similar relative potencies with the commercial reagents. Conversion factors are presented to relate results for LER-907, second IRP, or commercial standards. Commercially available reagents can provide a practical and reliable means of gonadotropin radioimmunoassay in blood or urine.
Liquid-chromatographic determination of guanidino compounds in plasma and erythrocyte of normal persons and uremic patients.
Authors: Kikuchi T , Orita Y , Ando A , Mikami H , Fujii M , Okada A , Abe H 
Published: January 2020

Abstract
We describe a method for determination of guanidino compounds in plasma and erythrocytes. The compounds are separated by liquid chromatography, the concentrations in the effluent being estimated fluorometrically (Trans. Am. Soc. Artif. Intern. Organs 24: 61, 1978). Guanidinoacetic acid, guanidinosuccinic acid, guanidinobutyric acid, guanidine, methylguanidine, taurocyamine, and arginine can be detected and quantitated in both plasma and erythrocytes from healthy individuals. The method was also applied to patients in chronic renal failure. Guanidinosuccinic acid, creatinine, guanidine, and methylguanidine are substantially increased in the plasma and erythrocytes of the uremic patient. Guanidino compounds can be effectively extracted from plasma with 0.5 volume of 300 g/L trichloroacetic acid, from erythrocytes with five volumes of 120 g/L trichloroacetic acid.
Internal sample attenuator counting (ISAC). A new technique for separating and measuring bound and free activity in radioimmunoassays.
Authors: Thorell J I 
Published: January 2020

Abstract
I describe a new method for the separation and counting of bound and free activity in radioimmunoassays. Particles containing a radiation-absorbing (attenuating) material are added to the assay. They shield the radiation from either the antibody-bound or the free radioligand. This obviates such manipulations conventionally involved in the separation and counting steps of radioimmunoassays as centrifugation and decanting. Bismuth oxide is used as the attenuator. Particles with different properties are described. In one type, bismuth oxide is combined with active charcoal in an agarose matrix and serves as an adsorbant for the free radioligand. In another type bismuth oxide is trapped within a polyacrylamide matrix to which antibodies are coupled. This particle can be used with a first- or a second-antibody bound activity. Application of the technique is illustrated with radioimmunoassays for thyroxin, triiodothyronine, human choriogonadotropin, and lutropin (luteinizing hormone).
One-minute electrochemical enzymic assay for cholesterol in biological materials.
Authors: Clark L C , Duggan C A , Grooms T A , Hart L M , Moore M E 
Published: January 2020

Abstract
In this rapid and specific micro-scale electrochemical enzymic assay for cholesterol and cholesterol esters, 10 microL of standard or sample is injected directly into a heated (50 degrees C) thermostated, oxystated cuvet containing pH 7.25 buffer, cholesterol oxidase (EC 1.1.3.6), and cholesterol esterase (EC 3.1.1.13). The cholesterol esters are hydrolyzed by the esterase, and the cholesterol is simultaneously oxidized by the oxidase. The hydrogen peroxide produced from oxidation of the unesterified cholesterol is measured by a polarographic anode covered with an acetate/polycarbonate membrane. The membrane allows hydrogen peroxide to diffuse to the platinum anode, where it is oxidized, but prevents the diffusion of ascorbic acid, uric acid, and bilirubin to the electroactive surface. Turbidity does not interfere. The correlation (r) between results by our method and the Abell-Kendall method for 105 samples of serum was 0.9994 and for 105 samples of plasma was 0.9997. Our method is convenient for the analysis of high-density lipoprotein cholesterol in plasma and serum supernates and in many kinds of tissue homogenates. Its limitations are also described.
Variability of total cholesterol concentrations in serum by repeated measurements in a large pediatric population--limitations of quality controls for laboratory analyses.
Authors: Sklov M C , Srinivasan S R , Webber L S , Berenson G S 
Published: January 2020

Abstract
We evaluated the variability in total cholesterol concentrations in serum in a large population of children over a period of time, to help us discern the limitations in reliability of current clinical laboratory methods for its analysis. We analyzed sera from a population of approximately 4000 children over a four-year period, quality-control sera, pooled sera, and surveillance samples from the Centers for Disease Control over a seven-year period, with a Technicon AutoAnalyzer II. Two methods of correction were suggested to adjust deviations in yearly serum total cholesterol means: yearly screening data were corrected on the basis of monthly variability in pooled-serum determinations and on the basis of deviations from values suggested by the Centers for Disease Control. Both correction methods were insufficient. These changes occur very slowly, and unless there is close monitoring and frequent comparison with a known standard, changes in laboratory results still can occur.
Effect of variations in globulin concentrations on serum radioimmunoassay results, as exemplified by choriogonadotropin.
Authors: Jawad M J , Wilson E A 
Published: January 2020

Abstract
Variations in serum protein concentrations can affect results of radioimmunoassay of human choriogonadotropin involving either polyethylene glycol or double-antibody methods of separation. Relative to the maximal binding of choriogonadotropin in the presence of normal (30 g/L) globulin concentrations, globulin concentrations of 10 to 60 g/L were associated with maximal binding ranging from 84.9 to 115.6% in the polyethylene glycol system, and from 109.9 to 92.5% in the double-antibody system. This effect was quantitatively much the same throughout the standard curve in the polyethylene glycol system, but diminished with the higher standard concentrations in the double-antibody system. In assays involving polyethylene glycol separation, an increase in globulin was associated with a linear increase in nonspecific binding, but no detectable effect of globulin on nonspecific binding was observed in the double-antibody system. Determination and compensation for nonspecific binding of individual samples (rather than for mean assay nonspecific binding) eliminated the globulin effect in the polyethylene glycol system but not in the double-antibody system.
Convenient radioimmunoassay for urinary human choriogonadotropin without interference by urinary human lutropin.
Authors: Wehmann R E , Harman S M , Birken S , Canfield R E , Nisula B C 
Published: January 2020

Abstract
We have devised a radioimmunoassay (RIA) for human choriogonadotropin (hCG) in first morning-voided urine specimens. Concanavalin A, a lectin, is used to extract and concentrate the hCG from urine. A high-affinity antiserum is used, directed to the hCG beta carboxy-terminal peptide, a unique immunological determinant not shared by the beta subunit of human lutropin. This ensures that urinary human lutropin-related molecules, which interfere with RIAs involving antisera to the intact hCG beta subunit, will not cross react in this assay. A concentrations of hCG as low as 0.4 microgram/L can be detected in the first morning-voided urine. The effective sensitivity of this assay for the unequivocal detection of hCG production is somewhat better than that achieved with the serum hCG RIA involving antisera to the hCG beta subunit. The improved specificity and sensitivity of this assay, and the greater convenience of collecting samples of urine rather than blood, are clinical useful advantages of this approach to assessing hCG production in humans.
A coupled NAD+-peroxidase spectrophotometric assay for cholesterol.
Authors: Avigad G , Robertson B 
Published: January 2020

Abstract
We describe a modified enzymic reagent for determination of cholesterol and cholesterol ester in serum and in high-density lipoprotein. In this new procedure, the hydrogen peroxide produced by the action of cholesterol oxidase is used as a substrate for NAD+ peroxidase. Spectrophotometric determination of the NADH consumed in this coupled reaction provides a direct and absolute measure of the cholesterol originally present in free form and that liberated by the action of cholesterol ester hydrolase.
Monoclonal antibodies to human IgG: reaction characteristics in the centrifugal analyzer.
Authors: Deverill I , Jefferis R , Ling N R , Reeves W G 
Published: January 2020

Abstract
We used monoclonal antibodies to human IgG in a kinetic turbidimetric method with a centrifugal analyzer. Results for total IgG with monoclonal and polyclonal reagents correlated well (r = 0.979). Within- and between-batch CVs compared favorably (3.1 and 4.8%, respectively, for polyclonal antisera and 3.5 and 4.0%, respectively, for monoclonal reagents). The monoclonal antibody combination used was shown to be of high titre, with an avidity toward the lower end of the range seen with conventional antisera to IgG. It displayed reaction characteristics similar to those observed with polyclonal antisera, although the time scale of reaction was extended and the effective concentration range was narrowed. Single monoclonal antibodies may not produce complexes of a size exhibiting measurable turbidity when reacted with soluble antigen. However, evidence is presented for the incorporation of such complexes into precipitates produced by other related antigen-antibody systems.
Unexplained increase in serum creatine kinase isoenzyme MB activity in a lung cancer patient.
Authors: Goffman T , Cantrell J , Schein P 
Published: January 2020

Abstract
In this case of mixed small cell--large cell cancer of the lung in an elderly woman, creatine kinase (EC 2.7.3.2) isoenzymes were assayed serially because of chest pain. The proportions of serum CK-BB and CK-MB isoenzyme activities were persistently above normal (CK-MB 10-18%, normal less than 5%). Electrocardiograms revealed no signs of ischemia or infarction. At autopsy no gross or microscopic infarction or inflammation of the heart was seen. There was also no infarction of smooth or skeletal muscle. The tumor was the probable source of most of the circulating CK-MB isoenzyme. Future cases may pose a similar diagnostic dilemma: differentiating creatine kinase that is present as a result of myocardial infarction from tumor-related CK-MB. Whether or not CK-MB assay could be useful in detecting tumors remains to be investigated.
Simultaneous determination of the four major catecholamine metabolites and estimation of a serotonin metabolite in urine by capillary gas chromatography of their tert-butyldimethylsilyl derivatives.
Authors: Muskiet F A , Stratingh M C , Stob G J , Wolthers B G 
Published: January 2020

Abstract
We have developed a routine capillary gas-chromatographic profiling method for simultaneous quantitative determination of the tert-butyldimethylsilyl derivatives of homovanillic acid, vanilmandelic acid, 3-methoxy-4-hydroxyphenylethylene glycol, and 3,4-dihydroxyphenylacetic acid and the estimation of 5-hydroxyindole-3-acetic acid in urine. The method is useful for diagnosis and followup of patients with functional tumors characterized by increased urinary excretion of metabolites originating from the metabolism of tyrosine and tryptophan--e.g., neuroblastoma, pheochromocytoma, carcinoid, and melanoma. It may also be applicable in pharmacokinetic studies of administered aromatic amino acids (parkinsonism, mental diseases, loading tests) and for diagnosis and followup of patients with inborn errors of metabolism that are characterized by organic aciduria (for instance, tyrosyluria and phenylketonuria).