bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Flavobacterium and Sphingobacterium species by enzyme profiles, with use of pattern recognition of two-dimensional fluorescence data.
Authors: Pau C P , Patonay G , Moss C W , Hollis D , Carlone G M , Plikaytis B D , Warner I M 
Published: January 2020

Abstract
Enzyme profiles of eight Flavobacterium species and one Sphingobacterium species were compared after using a two-dimensional fluorescence technique. Enzyme contents and corresponding activities were rapidly determined for whole-cell preparations after incubation with a mixture of preselected fluorogenic substrates. A two-dimensional fluorescence spectrum of the resulting product mixture, measured with a video fluorometer, provided a characteristic "fingerprint" for each organism. Comparison of fluorescent spectra was facilitated by a Fourier-transform-based pattern-recognition algorithm and by a clustering technique involving the Pearson product-moment correlation coefficient. F. multivorum, F. thalpophilum, and S. mizutae formed one cluster; F. indologenes, F. spiritivorum, F. odoratum, and F. balustinum formed a second. F. meningosepticum was intermediate between the first and second cluster, whereas F. breve was different from all other strains examined, based on their spectral dissimilarity indices and correlation coefficients.
A method for serum C1q based on its hydroxyproline content.
Authors: Rosano C L , Braun C B , Hurwitz C 
Published: January 2020

Abstract
The radial immunodiffusion assay overestimates the C1q in serum. Here we describe a convenient, accurate procedure for measuring C1q in 250 microL of dialyzed serum. This method is based on our previous findings that all C1q in serum precipitates with the euglobulin fraction and that all other serum proteins containing hydroxyproline are excluded from this fraction. Because C1q is 4.3% hydroxyproline, the concentration of C1q in serum can therefore be calculated from the hydroxyproline content of the euglobulin fraction. The procedure, all done in the same tube, consists of precipitating the euglobulin fraction, digesting it with HClO4, and converting hydroxyproline to the corresponding pyrrole, which is extracted with toluene and measured by absorbance at 560 nm.
Transferrin binding of Al3+ and Fe3+.
Authors: Martin R B , Savory J , Brown S , Bertholf R L , Wills M R 
Published: January 2020

Abstract
An understanding of Al3+-induced diseases requires identification of the blood carrier of Al3+ to the tissues where Al3+ exerts a toxic action. Quantitative studies demonstrate that the protein transferrin (iron-free) is the strongest Al3+ binder in blood plasma. Under plasma conditions of pH 7.4 and [HCO3-]27 mmol/L, the successive stability constant values for Al3+ binding to transferrin are log K1 = 12.9 and log K2 = 12.3. When the concentration of total Al3+ in plasma is 1 mumol/L, the free Al3+ concentration permitted by transferrin is 10(-14.6) mol/L, less than that allowed by insoluble Al(OH)3, by Al(OH)2H2PO4, or by complexing with citrate. Thus transferrin is the ultimate carrier of Al3+ in the blood. We also used intensity changes produced by metal ion binding to determine the stability constants for Fe3+ binding to transferrin: log K1 = 22.7 and log K2 = 22.1. These constants agree closely with a revision of the reported values obtained by equilibrium dialysis. By comparison with Fe3+ binding, the Al3+ stability constants are weaker than expected; this suggests that the significantly smaller Al3+ ions cannot coordinate to all the transferrin donor atoms available to Fe3+.
Recognizing hyperthyroidism in the elderly.
Authors: Nyström E , Lindstedt G , Lundberg P A , Lundholm K , Smith U 
Published: January 2020

Abstract
Hyperthyroidism in the elderly frequently presents with atypical symptoms such as apathy, anorexia, diarrhea, atrial fibrillation, and (or) cardiac decompensation. The diagnosis may therefore be delayed or missed, as illustrated by three cases. Laboratory thyroid evaluation is justified by a wide variety of indications in elderly persons who seek medical advice or care.
Characterization and assay of tartrate-resistant acid phosphatase activity in serum: potential use to assess bone resorption.
Authors: Lau K H , Onishi T , Wergedal J E , Singer F R , Baylink D J 
Published: January 2020

Abstract
We improved the spectrophotometric assay of tartrate-resistant acid phosphatase (TrACP; EC 3.1.3.2) activity in serum. During development of the assay we found that human serum contains a dialyzable, mixed-type noncompetitive inhibitor(s) of TrACP activity, the effects of which on the assay were substantially lessened by diluting the serum sample with water before assay and increasing the substrate concentration. Hemolysis releases into serum a significant amount of TrACP activity from erythrocytes, which can be inactivated by incubating the serum at 37 degrees C for 1 h before assay. Our improved assay was reproducible (CV = 5%), and measured within 10% of the amount of added bovine skeletal TrACP activity. Preliminary application of the assay revealed that the amount of serum TrACP activity in patients with skeletal diseases differed from normal values and changed in the same direction as the expected change in bone turnover, suggesting that TrACP activity in serum could be useful clinically as a marker of bone metabolism, possibly of bone resorption.
Enzymic ethanol assay: a new colorimetric method based on measurement of hydrogen peroxide.
Authors: Prencipe L , Iaccheri E , Manzati C 
Published: January 2020

Abstract
We describe a new colorimetric method for measuring ethanol in plasma by use of a peroxidase-coupled assay system and alcohol oxidase (EC 1.1.3.13) from Pichia species. Absorptivity is low enough to give useful results without sample dilution. The procedure is also applicable to saliva samples and utilizes only one working reagent. The absorbance of the blue dye that is formed is measured at 600 nm. The standard curve for the method is linear for ethanol concentrations up to 4 g/L. Average analytical recovery of ethanol in human plasma exceeded 99%. Within-run and between-run CVs were less than 2.45% and less than 1.92%, respectively. Results correlate very well with those by gas chromatography (r = 0.9977). The method is adaptable to automation.
Further investigations regarding the toxicity of sodium nitroprusside.
Authors: Butler A R , Glidewell C , McGinnis J , Bisset W I 
Published: January 2020

Abstract
Sodium nitroprusside is a valuable vasodilator, but its use has been curtailed because of numerous reports that, in the presence of blood, nitroprusside decomposes with release of toxic cyanide. We have examined the release of cyanide in terms of the known chemistry of nitroprusside and suggest that photochemical decomposition of nitroprusside and (or) its metabolism in vivo invalidates the analytical procedure used by previous workers. We also present evidence for the stability of nitroprusside in blood, based on 13C nuclear magnetic resonance studies.
Rapid determination of alpha-amylase activity by use of a new chromogenic substrate.
Authors: Dupuy G , Hilaire G , Aubry C 
Published: January 2020

Abstract
A new chromogenic substrate that is blocked at the nonreducing end, 4,6-benzylidene-alpha-D-4-nitrophenylmaltoheptaoside, is used to determine alpha-amylase (EC 3.2.1.1) activity in serum in a coupled assay with alpha-glucosidase (EC 3.2.1.20) and glucoamylase (EC 3.2.1.3) as auxiliary enzymes. The duration of the lag phase between 25 and 37 degrees C is less than 90 s, and the molar absorptivity of 4-nitrophenol is constant. The main cleavage product of the substrate by human pancreatic and salivary alpha-amylase is 4-nitrophenylmaltoside; in the presence of the auxiliary enzymes, greater than 95% of hydrolyzed substrate is accounted for as 4-nitrophenol. The combined reagent is stable for at least 20 days at 2-8 degrees C; precision is good, with CVs ranging from 1.7 to 3.3%; and the correlation of results with those by the 4-nitrophenylmaltoheptaoside method is excellent. Heparin (40 kilo-int. units/L), ascorbic acid (2.8 mmol/L), bilirubin (430 mumol/L), hemoglobin (170 mumol/L), glucose (55 mmol/L), and triglycerides (11 mmol/L) do not interfere in the assay.
Methods compared for determining glutathione peroxidase activity in blood.
Authors: Faraji B , Kang H K , Valentine J L 
Published: January 2020

Abstract
We compared four methods for determination of glutathione peroxidase (EC 1.11.1.9) activity, using blood samples from 52 healthy volunteers. Two methods depended on direct assay of the amount of glutathione remaining at specific time intervals; the two indirect methods involved measuring the rate of disappearance of NADPH. We assessed the precision and reproducibility of each method. One of the indirect assays proved to be far superior to the other methods. Results of each of the methods were correlated with one another. We present the normal reference intervals for glutathione peroxidase activity for all four methods.
Direct determination of angiotensin-converting enzyme inhibitors in plasma by radioenzymatic assay.
Authors: Reydel-Bax P , Redalieu E , Rakhit A 
Published: January 2020

Abstract
We describe a simple, rapid, specific radioenzymatic assay for "CGS 16617," a new, potent inhibitor of angiotensin-converting enzyme (ACE; EC 3.4.15.1) in human plasma. This assay is based on the principle that the inhibitor (i.e., the drug) binds to the ACE in plasma and hence the amount of free ACE in plasma is inversely related to the amount of active inhibitor present. Free enzyme is reacted with a radiolabeled substrate, and the radioactive product is selectively extracted into the scintillation cocktail for quantification. Fivefold-diluted plasma samples are incubated with [3H]hippuryl-glycyl-glycine enzyme substrate at 37 degrees C for 30 min and the liberated [3H]hippuric acid is selectively extracted into scintillation cocktail. The radioactivity is counted in a liquid scintillation counter. Both within-run and between-run, the variability (CV) of the assay is less than 10%. As little as 200 ng of the drug per liter can be quantified in 50-microL plasma samples. The method can also be used to assay two other ACE inhibitors, pentopril and CGS 14831, demonstrating that the method can be readily adapted to any ACE inhibitor having a single active component in plasma. The ester prodrug pentopril can also be assayed after ester hydrolysis. This method is suitable for analysis of large numbers of samples in clinical laboratories for routine monitoring of the concentrations of active ACE inhibitors in blood.
Prospective clinical evaluation of an improved fluorescence polarization assay for predicting fetal lung maturity.
Authors: Talt J F , Foerder C A , Ashwood E R , Benedetti T J 
Published: January 2020

Abstract
We performed a prospective clinical evaluation of our newly developed fluorescence polarization procedure to predict fetal lung maturity (Clin Chem 1986;32:248-54). Net fluorescence polarization was measured at 34 degrees C after a 6.5-min incubation of amniotic fluid with fluorophore. For the 26 cases of neonatal respiratory distress syndrome encountered in 196 deliveries, the net polarization exceeded 0.287 for 22 (85%) of these, and exceeded 0.260 for all 26. The specificity of the polarization assay equaled or exceeded the specificity of the lecithin/sphingomyelin ratio for all sensitivities greater than 70%. Neither assay was a good predictor of the clinical severity of respiratory distress. For a separate group of 21 amniotic fluid specimens clinically contaminated with blood or meconium, the discriminatory power of the polarization assay was decreased, but six of seven respiratory-distress cases still had polarization values greater than 0.260. We conclude that this fluorescence polarization assay is a better overall predictor of fetal lung maturity than is the lecithin/sphingomyelin ratio, and that polarization values less than 0.260 are associated with little risk of respiratory distress.
Discrepancies in carcinoembryonic antigen measurements: survey and control values vs values for patients.
Authors: Klee G G , Dodge L A , Reynoso G 
Published: January 2020

Abstract
We analyzed the carcinoembryonic antigen (CEA) test results reported in the College of American Pathologists' (CAP) surveys to determine the relationship between the source of CEA used to manufacture the survey specimens and the discrepancies among analytical methods. With the 1983 survey specimens, which were prepared from metastatic colon carcinoma, laboratories using Roche RIA with Clinetics columns reported results that were only one-half the values reported by laboratories using the Abbott polyclonal enzyme immunoassay. With the 1984 specimens, prepared from a different metastatic colon carcinoma, and the 1985 specimens, prepared from a tissue-culture source of CEA, the Roche results were about one-sixth as large as the Abbott results. These differences are larger than the reported assay differences for patients' specimens. In addition, twofold proportional differences were found when survey and control specimens were tested with different lots of Abbott polyclonal reagent, whereas only random differences were found with 102 patients' specimens. Evidently, assay systems perform differently with proficiency-testing and control specimens than with patients' specimens.
Clinical value of immunoradiometric assay of thyrotropin for patients with nonthyroidal illness and taking various drugs.
Authors: John R , Evans P E , Scanlon M F , Hall R 
Published: January 2020

Abstract
Using a two-site immunoradiometric assay, we measured concentrations of thyrotropin (TSH) in serum of 134 clinically euthyroid subjects, 93 patients with nonthyroidal illness, and 80 patients who were being treated with various drugs. Abnormal concentrations of TSH, free thyroxin, and free triiodothyronine, respectively, were recorded in serum of three (3.2%), 19 (20.4%), and 37 (39.8%) of the patients with nonthyroidal illness and in three (3.8%), five (6.3%), and 10 (12.5%) of the patients taking drugs. TSH could be detected in all patients' serum samples. We conclude that, for most patients without thyroid disease, a basal (i.e., unstimulated) measurement of their TSH concentration in serum will indicate their thyroid status more reliably than will assay of free thyroxin or free triiodothyronine.
Ascorbic acid as an antioxidant in measurements of catecholamines in plasma.
Authors: Hugh D , Grennan A , Abugila M A , Weinkove C 
Published: January 2020

Abstract
Sodium metabisulfite, commonly used to prevent the oxidation of catecholamines during extraction from plasma onto alkaline alumina, does not prevent their subsequent degradation in acetic acid eluates. However, ascorbic acid, a potent antioxidant, is extracted with the catecholamines onto the alumina and prevents such destruction. However, ascorbic acid may interfere with the electrochemical measurement of catecholamines, unless sequential oxidation and reduction are used. Other methods of minimizing catecholamine oxidation in acetic acid eluates include refrigerating at 4 degrees C and capping the sample vials to exclude atmospheric oxygen.
Erythrocytic glucose-6-phosphate dehydrogenase measured by a differential pH technique.
Authors: Barenghi L , Ceriotti F , Ripamonti M , Luzzana M , Bonini P 
Published: January 2020

Abstract
We propose a new quantitative electrochemical method for determining glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activity in purified erythrocytes or in whole blood, based on measurement of the pH change caused by oxidation of glucose 6-phosphate to 6-phosphogluconic acid, with simultaneous reduction of NADP+ to NADPH + H+. No sample pretreatment (e.g., preparation of hemolysate) is needed, and the automatic correction for sample blanks obviates interference from 6-phosphogluconate dehydrogenase (EC 1.1.1.44). The method is simple and fast, and the standard curve is linear to at least 2200 U/L at 37 degrees C. The within-day CV was 3.9% for activities in healthy individuals (mean value 1204 U/L), and 10% for deficient ones (classified as belonging to class II, mean value 407 U/L). Results (y) correlated well with those obtained with the WHO-recommended method (x): y = 1.13x + 0.02 (r = 0.971) for purified erythrocytes. Normal reference intervals are reported for the enzyme in purified erythrocytes and in whole blood.
Improved radioimmunoassay of melatonin in serum.
Authors: Sieghart W , Ronca E , Drexler G , Karall S 
Published: January 2020

Abstract
Melatonin was extracted from serum by using Baker reversed-phase C-18 columns. More than 99% of the applied melatonin was retained by the columns, and more than 97% was eluted from the columns in 300 microL of methanol. We then determined melatonin in the serum extract by a modification of a standard radioimmunoassay, using filtration instead of centrifugation to collect the [3H]melatonin-antibody complex precipitated by saturated ammonium sulfate. These modifications allow more rapid, accurate, and reproducible determination of melatonin than do previously published procedures.
Cardiac enzyme changes in myxedema coma.
Authors: Hickman P E , Silvester W , Musk A A , McLellan G H , Harris A 
Published: January 2020

Abstract
A 74-year-old man with myxedema and hypothermia had increased activities in plasma of creatine kinase (CK; EC 2.7.3.2), aspartate aminotransferase (AST; EC 2.6.1.1), and lactate dehydrogenase (LD; EC 1.1.1.27) and increased proportions of CK-MB (up to 20% of total CK) and LD1 isoenzymes, but no clinical or investigational evidence of associated myocardial infarction. This case illustrates that plasma enzyme activity and isoenzyme profiles in such clinical settings should be interpreted with caution, because increases in CK-MB and LD1 may relate to myxedema coma or hypothermia (or both) rather than to myocardial infarction.
Cross reactions in radioimmunoassay: a mathematical model for correcting assay results, as exemplified by eliminating the interference of intact thyrotropin in an assay of its beta subunit.
Authors: Dotti C , Ceda G P , Denti L , Cavalieri S , Borasi G , Valenti G 
Published: January 2020

Abstract
To correct the results of a radioimmunoassay for beta-thyrotropin (TSH) subunit by eliminating the proportion ascribable to intact TSH, we have devised a method that experimentally reproduces the conditions under which the interference develops. Beta-TSH subunit was assayed in several preparations containing known concentrations of both beta-TSH and TSH. The TSH-induced overestimation of beta-TSH was linearly related to the concentration of antigen in the sample. At a constant concentration of TSH, therefore, the following equation is applicable: F = aE + b, where F is the measured (but overestimated) concentration of beta-TSH, E is the actual concentration of beta-TSH, and a and b are the slope and the intercept of the regression line, respectively. a and b, once expressed as a function of TSH, allow the correction of the overestimation. The analysis of the results according to the mass action and conservation laws shows that the antiserum is more avid for the interferent (intact TSH) than for the antigen (beta-TSH).
Apolipoproteins C-II and C-III in serum quantified by zone immunoelectrophoresis.
Authors: März W , Schenk G , Gross W 
Published: January 2020

Abstract
Zone immunoelectrophoresis assays specific for apolipoprotein C-II and C-III have been developed. These simple, accurate, reproducible, and sensitive methods present valid alternatives to conventional immunoassays. In fasting normolipidemic men and women the concentrations of apolipoprotein C-II and C-III were 49 (SD 25) mg/L and 124 (SD 60) mg/L, respectively, with no sex-related differences for either apolipoprotein. The frequency distribution of apolipoprotein C-II was skewed to the right, whereas apolipoprotein C-III was bimodally distributed. Concentrations of each apolipoprotein correlated well with one another and with that of serum triglycerides, but there was virtually no correlation between the apolipoprotein C-II to C-III mass ratio and the concentration of triglycerides. Apolipoprotein C-III, but not apolipoprotein C-II, was statistically associated with total cholesterol.
Highly sensitive qualitative methods for serum choriogonadotropin (hCG): clinical specificity studies.
Authors: Bandi Z L , Schoen I , DeLara M 
Published: January 2020

Abstract
We screened six highly sensitive kits, designed for serum pregnancy tests, for false-positive results. The two best were then evaluated more extensively. The "BETA-hCG MAIA-clone" (I) and the "TANDEM ICON" (II) kits gave only negative results for 100 sera from men at 5, 10, and 25 int. units/L (1st IRP). Of 100 serum specimens from post-menopausal women three and 10 were hCG positive by the II and the I reagents, respectively, but only at the 5 int. units (1st IRP) of hCG per liter level of sensitivity. At 10 and 25 int. units/L, all specimens were negative by both tests. The manufacturers of these kits recommend pregnancy testing only at the 25 int. units/L level of analytical sensitivity. By quantitative methods, hCG concentrations in the II positive samples ranged from 6 to 20 int. units/L (1st IRP) and lutropin concentrations were between 130 to greater than 150 int. units/L. The medical records of the corresponding patients did not support the presence of trophoblast or any other hCG-secreting tissues. During 15 months of routine use of the II reagents at an analytical sensitivity of 25 int. units/L (1st IRP) hCG for pregnancy testing (greater than 4000 serum specimens from pre-menopausal women), the staff has not reported to us any suspected false-positive findings.
Hypothermic myxedema coma erroneously diagnosed as myocardial infarction because of increased creatine kinase MB.
Authors: Nee P A , Scane A C , Lavelle P H , Fellows I W , Hill P G 
Published: January 2020

Abstract
As is well recognized, activities of creatine kinase (CK, EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) in plasma may be substantially increased in hypothyroidism. We emphasize here that an increase and decrease in CK-MB isoenzyme, characteristic of acute myocardial infarction, can occur in hypothermic myxedema coma without myocardial infarction.
Postsynthetic modification of human enolase isoenzymes.
Authors: Rigiani N R , Wevers R A , Rijk E , Soons J B 
Published: January 2020

Abstract
The original form of beta beta enolase (EC 4.2.1.11) in tissue is modified to two more electrophoretically distinct forms when incubated with human serum. The three postsynthetic forms are designated beta beta 3, beta beta 2, and beta beta 1, in order of increasing anodal mobility and increasing modification. Serum and carboxypeptidases A and B all produce identical modifications of beta beta enolase but exhibit very different pH-activity profiles. A purified human serum protein previously named "modifying protein," which is responsible for the modification of creatine kinase-M and alpha-enolase subunits, modifies beta beta enolase and also has a pH-activity profile identical to that for serum. Thus we conclude that the modifying protein is not identical to either carboxypeptidase A or B; it may, however, be an as-yet-undescribed carboxypeptidase. With increased modification, both alpha alpha and beta beta enolase decrease in apparent activation energy; gamma gamma enolase shows no evidence of modification, and its apparent activation energy remains stable. Measurement of activation energy is an easy tool for screening for postsynthetic modifications in an enzyme.