bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activity of lactate dehydrogenase isoenzymes LD1 and LD2 in serum as determined by using an inhibitor of the M-subunit.
Authors: Tanishima K , Hayashi T , Matsushima M , Mochikawa Y 
Published: January 2020

Abstract
To measure activities of lactate dehydrogenase (EC 1.1.1.27) isoenzymes LD1 and LD2 in serum, we developed a method involving 1,6-hexanediol as specific inhibitor of the M-subunit. Addition of hexanediol, 0.6 mol/L, to five LD isoenzyme fractions purified from human liver and heart homogenates resulted in complete loss of activities of LD4 and LD5, and partial loss of LD2 and LD3. The activity of LD1, which is composed of the H-subunit only, was not affected. In studying what conditions would allow only the activities of LD1 or LD1 + LD2 to be expressed in serum, we found that the respective activities could be determined by treatment with hexanediol, 0.75 mol/L and 0.55 mol/L, respectively. Results of binding experiments and analytical-recovery tests supported the effectiveness of analyses with this inhibitor in determination of LD1 and LD1 + LD2 activities in serum. Results by this proposed inhibition method correlated well with those by the conventional electrophoretic method for determination of LD1 activity, but LD1 + LD2 activities by the inhibition method were a little less than those by the electrophoretic method, requiring some correction.
Immunochemical qualitative latex agglutination test for pancreatic lipase in serum evaluated for use in diagnosis of acute pancreatitis.
Authors: Møller-Petersen J , Klaerke M , Dati F , Toth T 
Published: January 2020

Abstract
In 417 patients (213 men, 204 women) consecutively hospitalized with acute abdominal pain we evaluated the clinical usefulness of a latex-agglutination test at admission to screen for concentrations of pancreatic lipase (EC 3.1.1.3) in serum greater than 300 micrograms/L. The diagnoses of acute pancreatitis (in 25 patients, 6%) and other diseases were made without knowledge of the results of the latex test or of quantification of pancreatic lipase in the serum by enzyme immunoassay. In the latex assay, when agglutination was taken as a positive test for acute pancreatitis, we found a diagnostic efficiency of 0.986 (95% confidence limits: 0.971-0.997) for acute pancreatitis. The predictive value of a positive latex test result with respect to acute pancreatitis was 0.807 (0.625-0.926); the predictive value of a negative test was 1.000 (0.991-1.000). Six patients had false-positive test results. No false-negative test results were found by enzyme immunoassay. We conclude that the latex agglutination test is useful as an emergency test for diagnosis of acute pancreatitis in patients with acute abdominal pain; negative results virtually exclude acute pancreatitis.
Spectrophotometric investigation of sensitive complexing agents for the determination of zinc in serum.
Authors: Homsher R , Zak B 
Published: January 2020

Abstract
Of two sensitive complexometric reagents for the colorimetry of serum zinc that we investigated, one, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP), was found to be a potentially useful compound for trace-metal determinations. It has a high molar absorptivity (120 000 L mol-1 cm-1) but is not convenient to use because it is not very soluble in water. The other reagent, a related pyridylazo compound, is 2-(5-bromo-2-pyridylazo)-5-(N-n-propyl-N-3-sulfopropylamino)phenol (5-BR-PAPS). It seems better suited for use in routine zinc determinations because, besides being water soluble, it has a higher molar absorptivity, 130 000 L mol-1 cm-1. Results by the proposed method developed with 5-Br-PAPS correlated well with those by atomic absorption spectrophotometry. The between-run CV for control sera was less than 5%; the within-run CV (same controls) was less than 4%.
Three techniques compared for detecting bacteriuria in symptomatic patients.
Authors: Warkentin D L , Rawling R A , Koppel W E , Maher G L , Broder P H , Marchand A 
Published: January 2020

Abstract
We wanted to determine whether the microscopic evaluation of urinary sediment could be replaced by either a biochemical determination (Chemstrip-9) or a colorimetric staining procedure (Bac-T-Screen), and to evaluate the feasibility of omitting from urinalyses attempts to culture urines. Cultures were considered positive when colony counts were greater than or equal to 10(3) for catheterized patients and greater than or equal to 10(4) for noncatheterized patients. The results of three separate studies on symptomatic patients showed a progressive decline in the sensitivity of the Chemstrip-9, which is a test for leukocyte esterase activity, and a difference in the sensitivity of the Bac-T-Screen between two of the studies. Neither test was consistently more sensitive or more predictive of a positive culture than was urine microscopy. By the end of the third study, we were convinced that the three methods are comparably sensitive and specific. Because 13 to 36% of positive cultures would be missed by these techniques, urine from symptomatic patients should routinely be cultured.
Application of a statistical approach to determining reference intervals in clinical chemistry.
Authors: Gallo C , Turco M C , Sanzi G , La Rocca S , Sacchetti L , Salvatore F 
Published: January 2020

Abstract
In clinical chemistry a linear-regression model may be used to determine reference intervals. A crucial point in this approach is the choice of variables to introduce into the model. In the present paper, we have applied a nonautomatic selection procedure, known as "element analysis," to a sample of 126 individuals from a small, ethnically homogeneous community in southern Italy. We investigated the effects of four independent variables--sex, age, weight, and alcohol consumption--on values for serum urea. Only sex and age proved to affect the urea values and were therefore introduced into the final model. This approach may be useful in determining reference intervals from observational studies when it is difficult to control a priori relevant factors. Moreover, variables may be selected not only on the basis of statistical criteria, but also according to biochemical and medical criteria.
Kinetic assay of gamma-glutamyltransferase with use of bilirubin oxidase as a coupled enzyme.
Authors: Satomura S , Miki Y , Hamanaka T , Sakata Y 
Published: January 2020

Abstract
We studied the kinetic measurement of gamma-glutamyltransferase (EC.2.3.2.2), coupling the reaction with that catalyzed by bilirubin oxidase (EC 1.3.3.5), which oxidizes and combines a phenylenediamine derivative with an aniline derivative to produce a green pigment. We measured the formation of the pigment kinetically (at lambda max745 nm, epsilon = 75 000 L mol-1 cm-1), with L-gamma-glutamyl-N-hydroxyethylaminoanilide as substrate and N-ethyl-N-hydroxy-3-sulfopropyl)-m-toluidine as a the coupling derivative. The within-run CV for measuring this reaction in samples of normal sera was 2.4%. A calibration plot of the change in absorbance per minute vs enzyme activity concentration showed good proportionality in the range of 0-1300 U/L. The results of this assay correlated well (r = 0.995) with those of the Boehringer method, in which L-gamma-glutamyl-3-carboxy-4-nitroanilide is the substrate. This new, highly sensitive procedure may be adapted to other assays involving phenylenediamine derivates as synthetic substrates.
Bioelectrochemical enzyme immunoassay of human choriogonadotropin with magnetic electrodes.
Authors: Robinson G A , Hill H A , Philo R D , Gear J M , Rattle S J , Forrest G C 
Published: January 2020

Abstract
We describe an amperometric technique for quantification of an enzyme immunoassay in which we use a magnetic working electrode, both to separate bound and free analyte and to monitor the electrochemical response. We used a "two-site" immunometric assay with monoclonal antibodies for human choriogonadotropin (hCG) as a model system in which magnetic particles were used as the solid phase. Separation of bound and free label is readily achieved by localizing the particles at the electrode. Activity of the bound enzyme in the environment of the electrode is determined electrochemically, permitting rapid quantification of the analyte without the need for a separate incubation step to measure enzyme activity. The sensitivity of the system is 150 int. units of hCG per litre (1st Int. Ref. Preparation). Correlation between the amperometric measurement of urinary hCG and data for an immunoradiometric assay was r = 0.9. The assay is rapid, requiring a total assay time for each sample of 20 min, which includes 15 min for antibody/antigen binding.
A quantitative automated immunoassay for fibrinogen/fibrin degradation products.
Authors: Schifreen R S , Cembrowski G S , Campbell D C , Craig A R , Demyanovich N D , Jurga-Hall P A , Reider M C , Schwartz M W , Tuhy P M , Waller S J 
Published: January 2020

Abstract
We describe a prototype quantitative automated assay for fibrin and fibrinogen degradation products, a particle-enhanced turbidimetric inhibition immunoassay (PETINIA) in the Du Pont aca discrete clinical analyzer. This assay involves a latex particle reagent with covalently bound fibrinogen and a polyclonal antiserum raised in rabbits against human fibrinogen. A special secondary sample-collection tube quantitatively removes fibrinogen from citrated plasma and inhibits further fibrinolysis, independent of heparin concentration. The assay range is 0-100 mg/L, in fibrinogen equivalents. The CV for the assay is less than 10% when performed with the aca. Nonclottable fibrin and fibrinogen fragments are measured by the assay, the greatest sensitivity being directed at the E domain of the fibrinogen molecule. We illustrate with case studies the potential of this assay for providing clinical information not obtainable with currently available qualitative and semi-quantitative assays.
Enzymatic correction of interference in the kinetic Jaffé reaction for determining creatinine in plasma.
Authors: Boyne P , Robinson B A , Murphy P , McKay M 
Published: January 2020

Abstract
We evaluated a simple, specific method for measuring plasma creatinine concentration, involving enzymatic degradation of creatinine before analysis by a kinetic Jaffé reaction. The enzymes--prepared in a dry, stable form--are convenient to use and eliminate the need to correct for sample dilution. As little as 50 microL of plasma is required, making the procedure ideal for use with samples from children. Between-day precision studies for determination of plasma creatinine at concentrations of 70 and 470 mumol/L yielded CVs of 7.8 and 4.3%, respectively. Analytical recovery of creatinine added to plasma samples ranged from 94 to 113%. Linear regression analysis demonstrated excellent agreement between results by this method and those by a "high performance" liquid-chromatographic technique.
Combined Immunochemical and Electrophoretic Determinations of Proteins in Paired Serum and Cerebrospinal Fluid Samples
Authors: Papadopoulos N M , Costello R , Kay A D , Cutler N R , Rapoport S I 
Published: January 2020

Abstract
Vol. 30
p 1815: The SD in the second column of the Table should read "0.09," not "0.9."
Vol 31
p 95, right column, last paragraph: The units for the protein concentrations should be mg/L.
Measurement of transferrin in human seminal plasma by a chemiluminescent method.
Authors: Caldini A L , Orlando C , Barni T , Messeri G , Pazzagli M , Baldi E , Serio M 
Published: January 2020

Abstract
We describe a luminescence immunoassay for measuring transferrin in human seminal plasma. Human transferrin conjugated with 7-[(N-4-aminobutyl)-N-ethylamino]naphthalene-1,2-dicarboxylic acid hydrazide was used to monitor the immunological reaction. The conjugate was stable for at least one year. The sensitivity (2 ng per tube) of the assay allows measurement of this protein in diluted seminal plasma. Results by this method (y) correlated well (r = .9681) with those by a conventional RIA method (x): y = 1.000x + 1.646 micrograms per ejaculate. Seminal transferrin concentrations are reported for normal control subjects, vasectomized subjects, and infertile patients. The method described appears suitable for measurement of seminal transferrin as an index of Sertoli cell function in male infertility.
Triclonal gammopathy in a patient with plasma cell dyscrasia.
Authors: Ray R A , Schotters S B , Jacobs A , Rodgerson D O 
Published: January 2020

Abstract
A triclonal gammopathy is an immunoglobulin abnormality in which three discrete monoclonal subpopulations of immunoglobulin molecules are present in a patient's serum. Monoclonal and biclonal gammopathies have been studied extensively, but relatively little is known about the much rarer triclonal gammopathies. The case described below illustrates some of the difficulties that this condition can present to the clinician and the clinical laboratory.
Urinary excretion rates of 15 free steroids: potential utility in differential diagnosis of Cushing's syndrome.
Authors: Schöneshöfer M , Weber B , Oelkers W , Nahoul K , Mantero F 
Published: January 2020

Abstract
To evaluate their potential usefulness in the differential diagnosis of Cushing's syndrome, we estimated the urinary excretion rates of the following non-metabolized, unbound steroid hormones: pregnenolone, progesterone, 17-OH-pregnenolone, 17-OH-progesterone, dehydroepiandrosterone (DHEA), androstenedione, testosterone, dihydrotestosterone, 11-deoxycorticosterone, 11-deoxycortisol, corticosterone, cortisol, 18-OH-11-deoxycorticosterone, 18-OH-corticosterone, and aldosterone. These were measured in normal subjects and in patients with Cushing's disease, adrenal adenoma, or ectopic corticotropin syndrome. We used "high-performance" liquid chromatography and subsequent radioimmunoassay. Our results indicate that simultaneous estimation of urinary free cortisol and DHEA may be useful in differential diagnosis of hypercorticoid states due to adrenal adenoma and Cushing's disease.
The chemistry of aluminum as related to biology and medicine.
Authors: Martin R B 
Published: January 2020

Abstract
The increasing number of roles discovered for Al3+ in physiological processes demands an understanding of how Al3+ interacts with compounds in biological systems. Al3+ is expected to complex with oxygen donor ligands, especially phosphates, and it does so in soils, in the gastrointestinal tract, and in cells. The stability of Al3+ complexes has generally been misjudged because of lack of recognition that free, aqueous Al3+ is not the dominant form in neutral solutions and that the solubility of Al(OH)3 limits the free Al3+ at the plasma pH 7.4 to less than 10(-11) mol/L. In the presence of inorganic phosphate, the permitted free Al3+ is decreased further, through formation of insoluble aluminum phosphate. This precipitate facilitates the elimination of Al3+ from the body. In contrast, citrate solubilizes Al3+, and an appreciable fraction occurs as a neutral complex that may pass through membranes and provide a vehicle for Al3+ absorption into the body. In the blood plasma the most likely small-molecule complex is that with citrate, while the only competitive protein complex is that with transferrin, a protein built to transport Fe3+ but whose sites are only 30% occupied.
Diagnostic significance of some urinary enzymes for detecting acute rejection crises in renal-transplant recipients: alanine aminopeptidase, alkaline phosphatase, gamma-glutamyltransferase, N-acetyl-beta-D-glucosaminidase, and lysozyme.
Authors: Jung K , Diego J , Strobelt V , Scholz D , Schreiber G 
Published: January 2020

Abstract
We compared the diagnostic validity of five urinary enzymes--alanine aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30), and lysozyme (EC 3.2.1.17)--as indicators of acute rejection crises in renal-transplant recipients. In 82 patients (group A), the excretion of each of these five enzymes was measured daily from transplantation until discharge from hospital. In another 69 patients (group B), enzyme determinations were made when the patient came for regular checkups (about every four to eight weeks). We used an "activity ratio" (the activity measured at a particular time compared with the activity on the preceding determination) value of 1.5 as the decision point. In group A, use of this discrimination point for alanine aminopeptidase, gamma-glutamyltransferase, and N-acetyl-beta-D-glucosaminidase yielded a specificity and sensitivity of about 90%. In group B, only alanine aminopeptidase had a greater diagnostic sensitivity than creatinine alone. Evidently, measurement of alanine aminopeptidase can be a helpful indicator of acute rejection crises, when interpreted in combination with other available relevant clinical, biochemical, and immunological data.
Relationship between serum lactate and ionized calcium in open-heart surgery.
Authors: Toffaletti J , Christenson R H , Mullins S , Harris R E 
Published: January 2020

Abstract
We studied 16 patients undergoing open-heart surgery and heart-lung bypass, to examine the relationship between ionized calcium and lactate. Blood was sampled at successive stages of the operation for measurement of ionized and total calcium, lactate, blood gases, pH, hematocrit, and other constituents. We found that correlations between ionized calcium and lactate were positive and statistically significant (p less than 0.05), both among and within patients. The linear regression of ionized calcium on lactate remained highly significant (p less than 0.0001) after adjustment for variability among patients and across operative stages as well as after correction for pH and hemodilution. The significant regressions between calcium and lactate, both before and after administration of calcium, indicate a relationship for calcium and lactate in patients undergoing open-heart surgery.
Measurement of urinary retinol-binding protein by enzyme-linked immunosorbent assay, and its application to detection of tubular proteinuria.
Authors: Topping M D , Forster H W , Dolman C , Luczynska C M , Bernard A M 
Published: January 2020

Abstract
An enzyme-linked immunosorbent assay (ELISA) for urinary retinol-binding protein (RBP) has been developed and compared with urinary beta 2-microglobulin for the detection of tubular proteinuria. The assay has a working range of 10 to 250 micrograms of RBP per liter of urine. The within-assay CV was 3.2-7.1%, the between-assay CV 12.5%. A control population of 118 male subjects gave a geometric mean urinary RBP concentration of 7.7 micrograms per millimole of creatinine and a 95th centile of 22 micrograms per millimole of creatinine. Comparison of urinary RBP and beta 2-microglobulin concentrations in 80 control subjects and 117 subjects exposed to cadmium fumes gave correlations of r = 0.59 and 0.91, respectively. Of the 117 subjects exposed to cadmium fumes, 103 gave both RBP and beta 2-microglobulin concentrations on the same side of the upper 95th centile values of 22 and 38 micrograms per millimole of creatinine for RBP and beta 2-microglobulin respectively (Chi-square analysis p less than 0.001), demonstrating that RBP and beta 2-microglobulin detect tubular proteinuria with equal sensitivity and specificity. ELISA and an established latex immunoassay gave well-correlated results.
Liquid-chromatographic determination of vitamin K1 in plasma, with fluorometric detection.
Authors: Haroon Y , Bacon D S , Sadowski J A 
Published: January 2020

Abstract
This assay for phylloquinone (vitamin K1) in plasma requires a single liquid-chromatographic step. Much smaller volumes of plasma (0.5-1.0 mL) are required than in previous assays. Before liquid chromatography, we purified crude lipid extracts by conventional chromatography on silica, then extracted the lipid fraction by dissolving it in an acidic mixture of hexane/acetonitrile (1/4 by vol) containing 70 mmol of zinc chloride per liter. The vitamin K1 was selectively extracted into acetonitrile after being converted to vitamin K1 hydroquinone by addition of zinc metal. This procedure removes greater than 99% of contaminating lipids. We injected the lipid extract directly onto a reversed-phase column after re-converting the vitamin K1 hydroquinone to vitamin K1. Vitamin K1 was quantified by comparison with the internal standard (dihydro-vitamin K1) and detected fluorometrically after post-column "on-line" reduction to the hydroquinone with zinc metal. The lower limit of detection for vitamin K1 in the final reversed-phase system was about 0.05 microgram/L plasma; CVs for replicates were less than 10%. The mean concentration of vitamin K1 in plasma from 22 healthy fasting adults was 0.55 (range 0.09-2.12) micrograms/L.
A multilayer element for determining hemoglobin in whole blood: principles and analytical performance.
Authors: Burdick B A , Hilborn D A , Wu T W 
Published: January 2020

Abstract
We described the structure and analytical performance of a thin-film element for determining total hemoglobin in whole blood. The element can be used with the Kodak Ektachem DT60 analyzer. The method, analogous to the standard Drabkin's method, provides accurate and precise results on 10-microL samples of undiluted whole blood. Dynamic range is linear from 0 to 200 g/L, and the method is relatively free from interference.
Activity concentration and mass concentration (monoclonal antibody immunoenzymometric method) compared for creatine kinase MB isoenzyme in serum.
Authors: Murthy V V , Karmen A 
Published: January 2020

Abstract
Results of the "Tandem-E CKMB" immunoenzymometric procedure (y) for creatine kinase (CK; EC 2.9.3.2) were compared with electrophoresis (x) for 160 serum samples from patients suspected of having sustained myocardial infarctions. The results correlated well: y, microgram/L (Tandem assay) = 1.3x-6.3 U/L(electrophoresis) (r = 0.95). CK-MB mass measurement was more stable than enzyme activity after storage and appeared to be more sensitive. Sera from 86 other people, which had no detectable CK-MB upon electrophoresis, gave a mean CK-MB value of 1.1 microgram/L (SD 1.3, range 0-8) with the Tandem assay. To determine whether these low values represented actual isoenzyme, we tested for possible interference by heterophile antibodies in the patients' sera by preincubating the samples with mouse serum before the Tandem assay. The mouse serum did not interfere with the assay of sera that had substantial quantities of CK-MB by electrophoresis. However, in five of six samples that were negative by electrophoresis, the CK-MB values were substantially smaller, indicating that the values measured were false-positives caused by the presence of heterophile antibodies directed against mouse proteins, an interference that could be eliminated by pretreatment with mouse serum.