bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radial-immunodiffusion assay of human apolipoprotein A-I with use of two monoclonal antibodies combined.
Authors: Marcovina S , Di Cola G , Catapano A L 
Published: January 2020

Abstract
We produced and characterized several monoclonal antibodies directed toward human plasma apolipoprotein A-I. Two of them, A-I-12 and A-I-57, individually precipitated purified or native high-density lipoprotein in agarose gel by double immunodiffusion. Because radial immunodiffusion performed with a single monoclonal antibody gave faint and diffuse rings of precipitation, we developed and optimized working conditions for using these two monoclonal antibodies combined to determine apolipoprotein A-I in human plasma. This combination gave easy-to-measure, clear, sharp rings, and linear and parallel standard curves for HDL3 (the primary standard) and a reference serum (the secondary standard). Moreover, no pretreatment of samples with dissociating agents or detergents is necessary. The assay was complete after overnight incubation, as compared with two to three days when polyclonal antisera were used. Apolipoprotein A-I concentrations as measured in 128 normolipidemic subjects and in 72 patients with various lipid disorders by the radial immunodiffusion technique with monoclonal antibodies (x) compared well (r = 0.882; y = 1.029x-0.036) with those measured by radial immunodiffusion with polyclonal antisera (y).
Improved fluorescence polarization assay for use in evaluating fetal lung maturity. II. Analytical evaluation and comparison with the lecithin/sphingomyelin ratio.
Authors: Foerder C A , Tait J F , Franklin R W , Ashwood E R 
Published: January 2020

Abstract
We assessed the analytical performance of an improved fluorescence polarization assay for use in evaluating fetal lung maturity and compared results with the lecithin/sphingomyelin ratio. During a three-month period 150 patients' samples were assayed by clinical laboratory personnel with both techniques. Values for the lecithin/sphingomyelin ratio correlate closely with net fluorescence polarization values (r = -0.85), less closely with net fluorescence intensity (r = 0.65). Background fluorescence intensity and polarization varied widely, indicating a need to correct measurements for endogenous fluorescence. Net fluorescence polarization values have a CV of 0.32% within-run, 1.07% between-day. A comparison of two amniotic fluid centrifugation procedures showed no significant difference in such values. For both methods, however, such values are slightly but significantly higher than those obtained for amniotic fluids without prior centrifugation. Short-term storage (less than 30 days) of uncentrifuged amniotic fluid samples at -20 degrees C does not significantly affect results.
Improved estimation of cholesteryl ester transfer/exchange activity in serum or plasma.
Authors: Groener J E , Pelton R W , Kostner G M 
Published: January 2020

Abstract
This simple, routine assay for measuring cholesteryl ester transfer/exchange activity in human plasma is based on the removal of interfering lipoproteins--very-low-density (VLDL) and low-density lipoproteins (LDL)--by precipitation with polyethylene glycol. High-density lipoproteins (HDL) in the samples do not affect the results. The supernate after precipitation is mixed with [14C]cholesteryl ester-labeled LDL as donor and with HDL as the acceptor for the cholesteryl ester. After incubation for 16 h at 37 degrees C, LDL is separated from HDL by precipitation with dextran sulfate and the radioactivity measured in the supernate, which contains the HDL. The assay is applicable to samples containing as much as 10 mmol of triglycerides per liter. The within-assay CV was 2.7%, the day-to-day CV 6.8%. Results compared well with those by conventional procedures.
Thrombin clotting activity measurement and standardization with lyophilized plasma.
Authors: Fenton J W , Wideman C S , Evatt B L 
Published: January 2020

Abstract
Thrombin-induced clotting times were inversely proportional to fibrinogen concentrations within the range of 98 to 2900 nmol/L; these reciprocal velocity measurements had units of seconds per clot. By analogy with classical enzyme kinetics, we defined rectangular hyperbolic parameters where Km(clot) ranged from 0.14 to 0.56 mumol/L and kclot from 0.020 to 0.075 clot per second. Specificity ratios (kclot/Km(clot)) showed that reconstituted lyophilized human plasma is as good, if not better, a source of clottable fibrinogen as the purified protein itself. These ratios also showed that the presence of greater than 98% of the autoproteolytic forms (beta- and gamma-thrombins) of the human enzyme did not interfere with clotting activity attributable to alpha-thrombin. Contrary to simple enzyme kinetics, velocities (reciprocal clotting times) were rectangular hyperbolically related to clotting activities. Clotting times between 5 and 90 s/clot correlated (r greater than 0.999) with reciprocal alpha-thrombin concentrations, permitting standardization with lyophilized plasma (1000 U.S. "NIH" thrombin-clotting units/L corresponded to approximately 21 s/clot with these plasma). Lyophilized plasma re-examined after 15 months displayed no change in clottability.
Derivative spectroscopic determination of paraquat in serum.
Authors: Kuo T L 
Published: January 2020

Abstract
A reliable and sensitive method is described for the quantitative determination of the herbicide paraquat in serum. It involves the formation of dodecyl sulfate-paraquat ion pairs, adsorption of these ion-pairs on XAD-2 resin, and determination of the sensitive derivative spectrum of reduced paraquat. Analytical recovery of paraquat added to serum was about 86% at concentrations of 0.02-1.0 mg/L. Assay sensitivity is 0.005 mg/L, but this could be increased two- to fivefold by using greater volumes (4-10 mL) of serum/plasma without encountering problems of turbidity. The proposed method also avoids interferences from severe jaundice, which generally occurs in patients with paraquat poisoning.
Change in concentrations of myogenic components of serum during 93 h of strenuous physical exercise.
Authors: Kosano H , Kinoshita T , Nagata N , Takatani O , Isobe M , Yazaki Y 
Published: January 2020

Abstract
Effects of 93 h of long, strenuous ranger training on activities of creatine kinase (CK) and lactate dehydrogenase (LD), along with their isoenzymes, and on concentration of myosin light chain were examined in sera of young soldiers. Total CK activity in serum was measured before, during, and after the training. Throughout, total CK activity in serum increased steadily. At the end of the training, activity of CK-MB was increased but its activity ratio to total CK remained unchanged; the activity ratio of LD1/LD2 also was not increased, although total LD activity was increased. Myosin light chain was increased by about fourfold at the end of the training and remained high for three days thereafter. However, its concentration was much lower than in myopathies such as polymyositis and Duchenne muscle dystrophy. The increased activities in serum of total CK and CK-MB isoenzyme on strenuous physical exercise evidently were of noncardiac origin. Although CK activity was comparable with that seen in myopathies accompanied by disintegration of skeletal muscle, the relatively low concentration of myosin light chain in serum suggests minimal skeletal muscle damage.
Prediction of fetal lung maturity by use of the Lumadex-FSI test.
Authors: Lockitch G , Wittmann B K , Snow B E , Campbell D J 
Published: January 2020

Abstract
We analyzed amniotic fluid from 91 pregnancies (estimated gestational age range 31 to 41 weeks), using the Lumadex-FSI Fetal Lung Maturity test (Beckman Instruments), and also determining phosphatidylglycerol content, the lecithin/sphingomyelin ratio, and foam stability index by the "shake test," and compared results with newborn outcome. Five of 64 babies born within 72 h of testing developed hyaline membrane disease. Except for the lecithin/sphingomyelin ratio, the predictive value of a negative test was 100% but that of a positive test was less than 50%. Use of all four tests did not offer diagnostic advantage over the use of Lumadex-FSI alone. For the laboratory that infrequently assesses fetal lung maturity, we believe the sealed cassette format of the Lumadex-FSI will permit better quality assurance than the shake test. The Lumadex-FSI test is intended to provide a graded estimate of positive risk for hyaline membrane disease, but more data from different centers and patient populations are needed to establish reliable predictive values.
Agarose electrophoresis and inhibitor tests for isoamylase determination can give complementary clinical information.
Authors: Gorus F , Deruyter L , De Waele B , Sevens C 
Published: January 2020

Abstract
We report the presence of an extremely high proportion of "aged" amylase in the serum and cyst fluid of a patient with a pancreatic pseudocyst. A salivary amylase inhibitor test helped us to differentiate these "aged" pancreatic amylases from salivary fractions having a similar electrophoretic mobility.
Degree of unsaturation of the fatty acid chains of phospholipids influences the fluorescence polarization: implications for evaluating fetal lung maturity.
Authors: Dohnal J C , Bowie L J , Burstein H J 
Published: January 2020

Abstract
To study the effect of fatty acid chain saturation on the fluorescence polarization assay as a measure of fetal lung maturity, we used purified phospholipids isolated from human amniotic fluid and various commercial phospholipids. We found that the fluorescence polarization value decreased as the concentration of unsaturated fatty acids increased. In contrast, the lecithin/sphingomyelin ratio increases with increasing amounts of saturated lecithin, produced as the fetal lung matures. Since only saturated lecithins are surface active, the two indices of fetal respiratory status must reflect different properties of lung surfactant.
Radioimmunoassay of atrial natriuretic peptides in human plasma.
Authors: Hartter E , Woloszczuk W , Stummvoll H K 
Published: January 2020

Abstract
The concentration of atrial natriuretic peptide (hANP) in plasma from venous blood of healthy subjects was measured by radioimmunoassay. hANP from 5 mL of EDTA-treated plasma was adsorbed onto Sep-Pak C18 cartridges, which were eluted with methanol/trifluoroacetic acid (5 mL/L), 90/10 by volume. The eluates were concentrated by evaporation under nitrogen and lyophilized. After redissolving the samples in 0.5 mL of sodium phosphate buffer, we incubated 100-microL aliquots with anti-alpha-hANP for 24 h, then added 125I-labeled alpha-hANP tracer; 24 h later, we separated the bound and free fraction by adding an antibody/polyethylene glycol complex as the second antibody. The sensitivity of the assay was 2 pg per tube (B0-3 SEM). In the useful range of B = 15 to 85% of B0, CVs for within-run and between-run precision did not exceed 8 and 12%, respectively. The 50% intercept of the standard curve was at 12 pg per tube. hANP concentrations for 36 healthy adults ranged from 8 to 68 ng/L.
Determination of tissue plasminogen activator and its "fast" inhibitor in plasma.
Authors: Chmielewska J , Wiman B 
Published: January 2020

Abstract
We describe efficient, accurate methods for specific determination of tissue plasminogen activator (t-PA, EC 3.4.21.31) and its "fast" inhibitor in plasma. In this coupled assay, a sample containing t-PA is incubated with plasminogen, a plasmin (EC 3.4.21.7) substrate of low Km and high Kcat, and fibrin as a stimulator. The inhibitor of t-PA is determined by incubating the sample with a known amount of t-PA in excess, then determining the residual t-PA. Both t-PA and t-PA inhibitor can be determined in many samples simultaneously within a few hours. These assays are modifications of procedures described by us (Clin Chim Acta 1983;127:279-88 and Thromb Res 1983;31:427-36). Their accuracy as assessed by analytical recovery of pure t-PA added to blood samples (91 +/- 4%) or of partly purified inhibitor added to plasma samples (102 +/- 10%) is satisfactory, as is their precision. For the t-PA assay the CV was 1.6% (within run) or 4.1% (between run). The corresponding values for the inhibitor assay were 4.5% (within run) or 8.4% (between run) if the inhibitor concentration exceeded 3 arb. units/mL.
Liquid-chromatographic detection of aspartylglycosaminuria.
Authors: Mononen T , Parviainen M , Penttilä I , Mononen I 
Published: January 2020

Abstract
We describe a specific, simple liquid-chromatographic method for detecting the lysosomal storage disease aspartylglycosaminuria. The method is based on identification and quantification of the major storage compound 2-acetamido-1-L-beta-aspartamido-1, 2-dideoxy-beta-D-glucose in the urine of affected individuals. Sample preparation and chromatographic analysis requires 30 min. Within-day variation of the method was less than 4.4%, between-day variation less than 11.7% (n = 10 each).
Dietary citric acid enhances absorption of aluminum in antacids.
Authors: Slanina P , Frech W , Ekström L G , Lööf L , Slorach S , Cedergren A 
Published: January 2020

Abstract
Ten healthy men ingested, twice daily between meals, during each of the seven-day experimental periods: (a) citric acid (as lemon juice), (b) Al(OH)3, or (c) Al(OH)3 + citric acid. Whole blood sampled after each dietary period was analyzed electrothermally after digestion with nitric acid. Moderate, but significant, increases in mean Al concentrations as compared with pretreatment values [5 (SD 3) micrograms of Al per liter] were seen after ingestion of either citric acid or Al(OH)3: 9 (SD 4) and 12 (SD 3) micrograms/L, respectively. Ingestion of both Al(OH)3 and citric acid resulted in a more pronounced, highly significant (p less than 0.001) increase in Al concentrations, to 23 (SD 2) micrograms Al/L, probably owing to formation and absorption of Al-citrate complexes.
Screening for thyroid disease in women greater than or equal to 50 years of age seeking hospital care: influence of common nonthyroidal illness on serum free thyroxin as determined by analog radioimmunoassay.
Authors: Nyström E , Petersen K , Lindstedt G , Lundberg P A 
Published: January 2020

Abstract
We determined free thyroxin (fT4; analog radioimmunoassay) and thyrotropin in serum of women greater than or equal to 50 years of age who were attending a medical casualty ward (n = 363) or a medical outpatient clinic (n = 496), in order to estimate the prevalence of low fT4 results associated with nonthyroidal illness and to screen for previously unknown thyroid disease. Individuals with results outside stated limits were followed up within two to four weeks. Only about 5% of the women seeking acute medical care showed a decrease in fT4 concentration in association with a normal thyrotropin concentration. As expected, this combination was even less common in outpatients. We found a prevalence of previously undiagnosed thyroid disease of clinical significance of 0.8% in medical acute-care cases, 1.8% in medical outpatients. For this clinical setting we regard the simple analog technique as acceptable in spite of the low values reported for some hospitalized patients with nonthyroidal illness.
New method ("SPAC ET") for free thyroxin in serum evaluated.
Authors: Plebani M , Perobelli L , Burlina A 
Published: January 2020

Abstract
We analytically and clinically evaluated a new commercial method ("SPAC ET") for simultaneously determining total and free thyroxin in serum. We found the method to be rapid, simple, and precise. Results significantly correlated with those by "symmetric" dialysis and also agreed with the clinical data for patients with extremely low or high concentrations of thyroxin-binding globulin. On contrast, in those patients the most commonly used thyroid indexes (free thyroxin index or thyroxin:thyroxin-binding globulin ratio) failed to correctly reflect the true functional status of the thyroid.
Immunoradiometric assay of thyrotropin as a "first-line" thyroid-function test in the routine laboratory.
Authors: Hopton M R , Harrop J S 
Published: January 2020

Abstract
We compared the utility of a sensitive immunoradiometric assay for serum thyrotropin as a "first-line" thyroid-function test with a strategy based on first measuring total thyroxin in serum. The immunoradiometric assay appears to distinguish primary hypothyroidism and hyperthyroidism from euthyroidism in "new" patients. The role of this test in monitoring antithyroid treatment or thyroxin-replacement therapy is not yet established, there being particular difficulty in interpreting low thyrotropin concentrations in such patients. Nevertheless, because a normal thyrotropin concentration in most, if not all, situations signifies the euthyroid state, thyrotropin determination by immunoradiometric assay merits consideration as an initial test by laboratories performing thyroid-function tests.
Direct determination of sulfate conjugates of 17-oxosteroids in urine by liquid chromatography.
Authors: Nishikaze O , Iwata J 
Published: January 2020

Abstract
We describe a new liquid-chromatographic method with fluorescence detection for direct simultaneous determination of four urinary sulfate conjugates of 17-oxosteroids (17OS), without use of solvolysis or enzymatic hydrolysis. The 17OS sulfates in urine samples are extracted with benzene as ion pairs in the presence of benzyltributylammonium chloride. These ion pairs are converted to hydrazones by use of dansyl hydrazine in trichloroacetic acid solution and then are separated by liquid chromatography. The proposed method, being simple and rapid, shows a good separation of 17OS sulfates and superior sensitivity, sufficient recovery, and good reproducibility.
Radioimmunoassay of prolactin in blood spotted on filter paper.
Authors: Bassett F , Gross B A , Eastman C J 
Published: January 2020

Abstract
In this method for estimating prolactin, 50 microL of whole blood obtained by finger puncture is spotted onto filter paper and blood-spot samples are "punched out" with a 3-mm (diameter) paper punch. The blood is extracted with aqueous buffers and the prolactin measured in large batches by radioimmunoassay. Results were identical with those for prolactin in serum. Prolactin in blood spots is stable at room temperature for up to one week and for several months at -20 degrees C. This simple technique for obtaining blood samples for prolactin estimation has particular potential for field studies of lactating women.
Densitometry and microchromatography compared for determination of the hemoglobin C and A2 proportions in hemoglobin C and hemoglobin SC disease and in hemoglobin C trait.
Authors: Krauss J S , Drew P A , Jonah M H , Trinh M , Shell S , Black L , Baisden C R 
Published: January 2020

Abstract
Using both densitometry and anion-exchange microchromatography, we measured hemoglobin C (Hb C) and Hb A2 proportions in 11 patients, eight of whom had Hb AC, two Hb SC, and one Hb CC. For one patient with Hb SC, we made the determinations before and after a transfusion. The mean (and SD) for the sum of Hb C + Hb A2 by densitometry and anion-exchange microchromatography for the nine patients with Hb AC and Hb CC were 45 (18) and 40 (18)%, respectively (p greater than 0.1, r = 0.98); for the three determinations involving the two Hb SC patients, the respective proportions were 40 (9.9) and 38 (6.6)% (r = 0.88). Electrophoretic analysis of microchromatographic eluates from the Hb AC and Hb CC patients showed that 6% of the absorbance of the late high-ionic-strength eluate was due to Hb C, which was responsible for the statistically insignificant difference between densitometric and chromatographic values for Hb C + A2 values. Electrophoresis on cellulose acetate of concentrated eluates of the Hb C + A2 fraction from the two Hb SC patients revealed no contamination by Hb S. Evidently, microchromatography can be used to determine Hb C + A2 in patients with Hb C or Hb SC disease or Hb C trait.
Ascorbate in plasma as measured by liquid chromatography and by dichlorophenolindophenol colorimetry.
Authors: VanderJagt D J , Garry P J , Hunt W C 
Published: January 2020

Abstract
Ascorbic acid was measured in 125 plasma samples by an automated colorimetric method involving dichlorophenolindophenol and by a "high-performance" liquid-chromatographic procedure with electrochemical detection. The two methods gave comparable results for samples with ascorbate concentrations of 1 to 20 mg/L (r = 0.97). We also measured the amount of total ascorbate (ascorbic acid + dehydroascorbic acid) in the same samples by a liquid-chromatographic procedure with precolumn derivitization of ascorbic acid. We confirmed that plasma contains little dehydroascorbic acid.
Simplified liquid-chromatographic determination of vancomycin.
Authors: Rosenthal A F , Sarfati I , A'Zary E 
Published: January 2020

Abstract
We simplified determination of vancomycin in serum by using a direct and rapid solvent precipitation of protein and by using a simple organic compound as internal standard. Reproductibility of the vancomycin retention time was improved by modifying the mobile phase. Data obtained by fluorescence polarization immunoassay correlated well, and there was little bias between the two methods. The present method is sufficiently rapid to make this a practical choice for many laboratories.
Liquid-chromatographic determination of hemoglobin A2.
Authors: Turpeinen U 
Published: January 2020

Abstract
In this liquid-chromatographic assay for hemoglobin A2 (Hb A2) in human blood, the blood samples are hemolyzed by dilution and the hemolysates are chromatographed on a weak cation-exchanger with a solvent gradient of a buffer with two different ionic strengths. The absorbance of the effluent is monitored at 405 nm. The retention time of Hb A2 is less than 10 min. The mean within-assay CV was 1.6%, the between-assay CV 4.9%. I describe the effects of various column dimensions and sample preparation methods on the separation of Hb A2. The normal reference interval (for 54 healthy adults) was 1.3 to 3.0%. A comparison between results by a minicolumn method and by the present method is performed. Rapid and reproducible, this method is suitable for use in routine determination of Hb A2.
Simplified methods for measuring cholesterol concentrations of high-density lipoprotein subclasses in serum compared.
Authors: Whitaker C F , Srinivasan S R , Berenson G S 
Published: January 2020

Abstract
We used a combination of heparin micro-affinity column chromatography and heparin-Mn2+/dextran sulfate (DS) precipitation procedures to measure directly the total high-density lipoprotein (HDL)-cholesterol and HDL3-cholesterol in serum. The value for HDL2-cholesterol was obtained by subtracting the value for HDL3-cholesterol from that for total HDL-cholesterol. Results of this methodology and of the original heparin-Mn2+/DS double-precipitation method were compared with those of preparative ultracentrifugation. Concentrations of HDL- and HDL2-cholesterol by the original double-precipitation method were respectively 26 and 33 mg/L lower than by the ultracentrifugation method (p less than 0.001). Corresponding values by the micro-affinity/precipitation method were 36 and 29 mg/L higher than by the ultracentrifugation method (p less than 0.001). The values for HDL3-cholesterol by ultracentrifugation and by precipitation differed only by 7 mg/L (p greater than 0.05). Micro-affinity/precipitation and double-precipitation results both correlated well with those by ultracentrifugation (r = 0.84 to 0.94); the y-intercept of the comparison with the micro-affinity/precipitation method was close to zero. Use of the micro-affinity/precipitation method with samples from black or white adolescents showed that the blacks had higher concentrations of HDL2-(p less than 0.01) and HDL3-cholesterol (p less than 0.02) than did the whites.