bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biochemical markers in the assessment of protein-calorie malnutrition in premature neonates.
Authors: Nadeau L , Forest J C , Masson M , Morrissette I , Larivière F , Caron M 
Published: January 2020

Abstract
We studied 135 premature newborns of 26 to 36 weeks gestation, divided into three groups: the control group, 66 premature infants with uncomplicated course; 51 premature neonates with appropriate birth weight for gestational age (AGA), who suffered from clinical problems that delayed oral feeding; and 18 premature infants with small birth weight for gestational age (SGA). When neonates of the same postnatal age were compared, prealbumin concentrations were the lowest in the SGA group at the third and fourth postnatal week. Although the AGA group had the most infants with serious illnesses and the lowest protein-calorie intakes, their prealbumin concentrations did not differ significantly from those of the control group. But when the infants of each group were subdivided on the basis of intakes and weight gain regardless of postnatal age, those with greater intakes showed significantly higher prealbumin values; however, in all groups, the infants with higher intakes were also significantly older. Total proteins and albumin showed similar changes in all groups. Prealbumin concentrations showed great interindividual variability in infants of the same postnatal age. We conclude that prealbumin, albumin, and serum total proteins are not sufficiently sensitive biochemical markers to assess alterations of the nutritional status of premature infants.
Simultaneous liquid-chromatographic determination of five antiarrhythmic drugs and their major active metabolites in serum.
Authors: Proelss H F , Townsend T B 
Published: January 2020

Abstract
We report an isocratic "high-performance" liquid chromatographic method for the simultaneous measurement of tocainide, lidocaine, procainamide, quinidine, disopyramide, and their major active metabolites in serum. The drugs are extracted from 200 microL of serum at pH 9.5 with 1.5 mL of 1,2-dichloromethane, concentrated by evaporation, and separated on a CN-bonded-phase column at 40 degrees C (flow rate 2 mL/min) with a pH 7.1 mobile phase of acetonitrile/methanol/phosphate buffer (60/7/33, by vol); the phosphate buffer contains 10 mmol of KH2PO4 and 0.5 mmol of triethylamine per liter. The antiarrhythmic drugs elute in the K' (capacity factor) range of 1.43 (lidocaine) to 5.7 (disopyramide). Results vary linearly with drug concentration to at least 30 mg/L; the detection limit is 0.1-0.2 mg/L. Within-run precision (CV) ranges from 0.9% to 5.0% and day-to-day precision from 2.1% to 6.2%, depending on the specific drug and its concentration in serum. Extraction efficiencies vary from 76% to 85% and analytical recoveries from 98.5% to 103%. At toxic serum concentrations, several basic drugs may interfere with the assay of some antiarrhythmics, but only hydroxyzine, verapamil, and certain local anesthetics interfere at therapeutic concentrations.
Evaluation of a monoclonal immunoenzymometric assay for alpha-fetoprotein.
Authors: Chan D W , Kelsten M , Rock R , Bruzek D 
Published: January 2020

Abstract
A monoclonal immunoenzymometric assay for alpha-fetoprotein was evaluated for detection and monitoring of hepatocellular carcinoma (HCC). We studied 1343 serum specimens from 759 patients with various neoplastic and non-neoplastic diseases. The interassay CV for this assay (M-AFP) ranged from 3.5 to 5.5%, with a minimum detectable concentration of 2.2 micrograms/L, as compared with 10 micrograms/L for a polyclonal (P-AFP) RIA for AFP. The calibration curve (0-300 micrograms/L) was linear, and serum dilutions paralleled it. The reference interval (0-9 micrograms/L) was established from data on 111 healthy subjects. Regression analysis of the AFP concentration (0-300 micrograms/L) of HCC patients obtained with the M-AFP assay (y) and the P-AFP RIA (x) yielded the equation y = (1.125)x - 0.52 (r = 0.9395, n = 165), with a considerable number of discrepant results for AFP less than 100 micrograms/L. By M-AFP immunoassay, AFP was above-normal (greater than 9 micrograms/L) in most HCC patients (80%), and to a lesser extent in other liver tumors (48%). AFP was within the normal reference interval for most patients with germ-cell tumors or benign liver disease and for other disease groups. For maximum diagnostic efficiency (90%) for HCC the decision level was increased to 100 micrograms of AFP per liter. Changes in serum AFP were correlated with changes in tumor volume in most HCC patients.
Assays for thyrotropin-receptor binding and thyroid-stimulating antibodies in sera from patients with Graves' disease.
Authors: Massart C , Hody B , Mouchel L , Edan G , Nicol M 
Published: January 2020

Abstract
We compared the activities of thyroid-stimulating antibodies (TSAb) measured in cultures of human thyrocytes and the values for thyrotropin-receptor antibodies (TRAb) as measured with a commercial kit based on use of radiolabeled receptors. Sera were obtained from patients with Graves' disease before, during, and after therapy with carbimazole (1-methyl-2-thio-3-carbethoxyimidazole). We found a significant correlation between the measurements of these two antibodies in patients: before treatment (r = 0.74, p less than 0.01, n = 44), after three months of treatment (r = 0.76, p less than 0.01, n = 21), and during relapse after the drug was discontinued (r = 0.64, p less than 0.01, n = 19). In all three situations, our TSAb technique was more sensitive than the TRAb method. We conclude that, even though the TRAb technique is simpler and quicker, this commercial kit is too insensitive to replace measurement of TSAb in fresh human thyrocyte cultures for management of drug therapy of patients with Graves' disease.
Effects of therapeutic hypothermia on activity of some enzymes in cerebrospinal fluid of patients with anoxic-ischemic brain injury.
Authors: Vaagenes P 
Published: January 2020

Abstract
I assessed the effect of therapeutic hypothermia on the activity in cerebrospinal fluid of creatine kinase (EC 2.7.3.2) and its brain isoenzyme (CK-BB), lactate dehydrogenase (EC 1.1.1.27), and aspartate aminotransferase (EC 2.6.1.1.) as markers of cerebral damage in patients with transient anoxic-ischemic brain injury. Moderate hypothermia (30-32 degrees C) lasting more than 24 h resulted in disproportionately greater activity of creatine kinase during the post-insult period than in patients not treated with hypothermia but having similar insults and outcome (p less than .01 for survivors, and p less than .005 for nonsurvivors). No differences were observed for the thermostable enzymes lactate dehydrogenase and aspartate aminotransferase, which demonstrates that the effect of hypothermia must be taken into account when thermolabile enzymes are used as sole markers of brain damage in such patients.
Use of the caffeine reagent in direct spectrophotometry of bilirubin.
Authors: Vink K L , Schuurman W , van Gansewinkel R 
Published: January 2020

Abstract
The molar absorptivity of unconjugated bilirubin in caffeine reagent is independent of the protein matrix. This finding, together with the simplicity of a dilution step for direct spectrophotometry, will improve the calibration methods of bilirubin and make them more nearly accurate. This is encouraging for the development of a new method for bilirubin determination in neonates; moreover, the caffeine reagent has a clearing influence on the turbidity of human sera. These findings should also be important for standardization, especially because the method of Jendrassik and Gróf is also protein-independent. Therefore, the introduction of one reliable, inexpensive, "universal" standard of bilirubin in bovine serum albumin will be of importance for both methods.
The Stratus immunofluorometric assay system evaluated for quantifying human choriogonadotropin in serum.
Authors: Rogers L C , Kahn S E , Oeser T H , Bermes E W 
Published: January 2020

Abstract
We evaluated the Stratus (American Dade, Miami, FL), an automated immunofluorometric assay system, for the quantification of human choriogonadotropin (hCG) in serum or plasma. The assay is based on the "sandwich" (two-site) immunoassay methodology: use of two monoclonal antibodies, one specific for the alpha subunit and the other for the beta subunit, results in an assay that is specific for the intact hCG molecule. Results for the first sample are obtained in 7 min; subsequent additional values are produced at 1-min intervals. Inter-run precision (CV), estimated from replicate determinations of sera, was 4.5% at an hCG concentration of 38 int. units/L, 4.9% at 114, and 6.1% at 194. Intrarun CV was less than 2% at all three concentrations. Correlations of results for 127 specimens analyzed in duplicate with the Stratus (y) and by a radioimmunoassay (x) for beta hCG (Gamma Dab M [cf931125I] beta-hCG, Travenol-Genentech Diagnostics, Cambridge, MA) yielded the following regression equation: y = 0.969x - 6.0 (r = 0.995). The Stratus immunofluorometric system provides a rapid and convenient assay of hCG in serum or plasma.
A case of immunoglobulin G conjugated with lactate dehydrogenase, producing both loss of enzyme activity and an abnormal isoenzyme pattern.
Authors: Sudo K , Maekawa M , Watanabe H , Matsumoto K , Mori Y , Sasaki T , Kanno T 
Published: January 2020

Abstract
We present a patient with an inhibitor of lactate dehydrogenase (LD; EC 1.1.1.27) in serum, who had pericarditis and myocardial hypertrophy. The patient's LD activity in serum was low and the LD isoenzyme pattern was abnormal. The relative molecular mass of this abnormal LD-IgG complex was approximately 490 000. The patient's IgG reacted with all five LD isoenzymes.
Measurement of ionized calcium in serum with ion-selective electrodes: a mature technology that can meet the daily service needs.
Authors: Bowers G N , Brassard C , Sena S F 
Published: January 2020

Abstract
This article reviews key advances in ion-selective electrode technology that have made potentiometric measurements of ionized calcium (Ca2+) reliable and precise. Our use of two second-generation Ca2+ analyzers (Radiometer ICA1 and NOVA 8) made possible uninterrupted service as volume increased to 31 640 patient tests in 1985. The lower results on the NOVA 8 were adjusted upwards to match those of the ICA1 to give identical results. Both analyzers were evaluated under working conditions of high volumes and multiple operators to establish downtime, electrode life, and costs. We have classified all Ca2+ analyzers into first-, intermediate-, and second-generation instruments, the better to understand their differences. Results for large numbers of patients' sera were shown to be systematically different when any two analyzers were compared. These differences are the consequence of each manufacturer's unique choices of the following: (a) the matrix of the calcium calibration solutions, (b) the type and configuration of the reference electrode, and (c) the salt-bridge solution. Elimination of each analyzer's biases will require agreement on a reference system that defines the accuracy of Ca2+ measurements on serum, plasma, or whole blood. The sound analytical performance of today's second-generation Ca2+ analyzers has allowed us to exploit the inherent superiority of Ca2+ over total calcium (CaT) measurements in the daily care of patients. We report on the preference of Ca2+ over CaT by physicians at our hospital since the introduction of second-generation Ca2+ analyzers. Therefore, we state unequivocally from our very satisfactory experience over the past five years that Ca2+ is a clinical laboratory test whose time has come!
Detection of anti-laminin antibodies in sera by latex agglutination.
Authors: Bernard A M , Foidart J M , Mahieu P , Viau C , Lauwerys R R 
Published: January 2020

Abstract
We describe a latex particle agglutination assay for detecting circulating antibodies against laminin, a noncollagenous glycoprotein of basement membranes. Polystyrene latex particles on which laminin has been adsorbed are incubated with serum for about 25 min at 42-45 degrees C. The agglutination is then measured by counting residual unagglutinated particles. Polyethylene glycol 6000 enhances the agglutination. The assay is fully automated, yielding results in about 45 min, for 50 samples per hour. Addition of purified laminin abolishes the agglutination of laminin-coated particles in practically all positive sera. The anti-laminin antibody titers obtained by this latex immunoassay and by radioimmunoassay correlated well in 161 sera from patients with suspected or established renal diseases. The agglutination assay more frequently gave positive results for cases of glomerulonephritis with linear deposits (20/22 cases) than for glomerulonephritis with granular deposits (7/68) or glomerulonephritis with no glomerular deposits (2/13). The finding of low anti-laminin antibody titers in sera from about 15% (34/230) of the healthy subjects suggests that these autoantibodies are pathogenic only in certain circumstances.
Two new monoclonal antibody-based enzyme-linked assays of apolipoprotein B.
Authors: Young S G , Smith R S , Hogle D M , Curtiss L K , Witztum J L 
Published: January 2020

Abstract
We describe two new monoclonal antibody-based, solid-phase immunoenzymometric assays for the quantification of apolipoprotein (apo) B in plasma: a competitive assay and a direct assay. For both, we utilize 96-well microtiter plates and native low-density lipoprotein (LDL) for preparing the standard curve. A single monoclonal antibody, MB24, is used in the competitive assay. The direct assay involves use of two monoclonal antibodies, MB24 and MB47. These two antibodies bind to distinct, unrelated apo B epitopes expressed by all LDL particles, and both antibodies detect apo B in very low-density and intermediate-density lipoproteins as well as LDL. With the two-step competitive assay, which involves use of LDL-coated microtiter plates, the intra- and interassay reproducibility in plasma apo B measurements averaged 6% and 12%, respectively. In the one-step direct assay, which takes less than 2 h for completion, plasma samples and peroxidase-labeled MB24 are incubated simultaneously on MB47-coated microtiter wells. The amount of labeled MB24 bound to lipoproteins trapped by MB47 is proportional to apo B concentration. With the direct assay, intra- and interassay CVs averaged 7% and 12%, respectively. These assays are simple, reproducible, involve convenient incubation intervals, and do not require radioisotopes; thus they can be widely applied in clinical laboratories.
Incidence and specificity of interference in two-site immunoassays.
Authors: Boscato L M , Stuart M C 
Published: January 2020

Abstract
Using a modified "two-site" immunoradiometric assay, termed an "interference assay," we have demonstrated the occurrence of non-analyte antibody-binding substances in approximately 40% of serum samples. These substances multivalently bind antibodies from any of several species at a site other than the antigen-binding site. Using a two-site immunoradiometric assay for human choriogonadotropin, we have investigated their effect on analyte quantification. In this system these antibody-binding substances mimic the presence of analyte; when analyte is actually present, they can also cause over- or underestimates. Addition of excess nonspecific immunoglobulin from an appropriate species eliminates this interference. However, the amount of nonspecific immunoglobulin added to an assay system may not always be enough to block interference in all samples.
Effect of phospholipase C on high-molecular-mass alkaline phosphatase in serum.
Authors: Sykes E , Kiechle F L , Epstein E 
Published: January 2020

Abstract
Electrophoresis of some serum samples on polyacrylamide gel, followed by staining for alkaline phosphatase (EC 3.1.3.1), produces a band of activity at the gel origin. This high-Mr band consists of liver membrane fragments containing alkaline phosphatase and other enzymes. Alkaline phosphatase is closely associated with phosphatidylinositol in liver plasma membranes, and we have found that phospholipase C (EC 3.1.4.3) from Bacillus cereus, known to possess some phosphatidylinositol specificity, was able to release liver alkaline phosphatase from the high-Mr band. Two preparations of phospholipase C from Clostridium perfringens, however, which has no phosphatidylinositol specificity, had no effect on the alkaline phosphatase activity in the high-Mr band.
A new method for reporting the sources of abnormal activities of lactate dehydrogenase in serum.
Authors: Politser P E , Powell S H , Fink J 
Published: January 2020

Abstract
We have developed and tested a new method to increase the diagnostic usefulness of measurements of lactate dehydrogenase (LDH; EC 1.1.1.27) isoenzymes. The method estimates the separate contributions from enzymatically distinct organ clusters (e.g., heart/kidney/erythrocyte, liver/muscle, lung) to the total activity of LDH in serum. To test this method, we monitored serum LDH isoenzymes over the entire hospital course of 73 patients admitted to the intensive-care unit with chest pain, myocardial infarction, or serious hemodynamic disturbances. The organ-specific estimates provided useful information beyond measurements of the original isoenzymes. The sensitivity and specificity of this new method in detecting acute myocardial infarction, as well as concomitant disorders involving the liver or lung, are significantly greater than those of other diagnostic indices or pathologists' judgments. Serial plots of the organ-specific estimates may provide additional insight into evolving pathophysiological processes.
Assessment of immunochemical methods for determining low concentrations of albumin in urine.
Authors: Watts G F , Bennett J E , Rowe D J , Morris R W , Gatling W , Shaw K M , Polak A 
Published: January 2020

Abstract
Four immunochemical methods (radioimmunoassay, RIA; radial immunodiffusion, RID; immunoturbidimetry, IT; enzyme-linked immunosorbent assay, ELISA) for measuring urinary albumin at low concentrations were assessed for their assay characteristics and practicability. Precision and accuracy were comparable between the methods when studied individually. We made a method comparison, with RIA as reference, using urine samples from diabetic patients with albumin concentrations ranging from 1 to 120 mg/L. There was no significant systematic difference between RID and RIA, but IT and ELISA gave consistently lower values than RIA, the mean differences being 1.8 (p less than 0.01) and 9.7 mg/L (p less than 0.001), respectively. Random error, compared with that for RIA, was in increasing order: RID (residual SD = 3.8 mg/L); IT (4.3 mg/L); ELISA (7.3 mg/L). The difference between the methods increased with the albumin concentration. Operational cost was highest with IT, lowest with RIA. Capital cost was highest with RIA and lowest with RID, which required most technical skill. ELISA had intermediate overall costs.
Alkaline phosphatase isoenzymes resolved by electrophoresis on lectin-containing agarose gel.
Authors: Schreiber W E , Whitta L 
Published: January 2020

Abstract
With this electrophoretic method the liver, biliary, and bone isoenzymes of alkaline phosphatase are clearly separated on agarose gels. Wheat-germ lectin, incorporated in the gel matrix, binds the bone isoenzyme selectively, forming a precipitate near the origin. Neither liver nor biliary isoenzyme is affected. Activity staining with an indigogenic dye substrate reveals the liver isoenzyme migrating nearest the anode, followed by the biliary and bone isoenzymes. Results are generally similar to those of electrophoresis on cellulose acetate. However, the lectin-agarose gels better resolve the liver and bone isoenzymes, and heat treatment of samples is not required before electrophoresis.
CEDIA, a new homogeneous immunoassay system.
Authors: Henderson D R , Friedman S B , Harris J D , Manning W B , Zoccoli M A 
Published: January 2020

Abstract
Genetic engineering of beta-galactosidase (EC 3.2.1.23) has led to the development of a new homogeneous assay system, CEDIA. The Z gene of the lac operon of Escherichia coli encodes a large enzymatically inactive polypeptide that spontaneously aggregates and folds to form active beta-galactosidase. Using recombinant DNA techniques, we have been able to engineer beta-galactosidase protein into a large polypeptide (an enzyme acceptor, EA) and a small polypeptide (an enzyme donor, ED). The EAs and EDs are both enzymatically inactive, but spontaneously associate to form enzymatically active tetramers. In the assay, hapten or analyte is attached to an ED, and an analyte-specific antibody is used to inhibit the spontaneous assembly of active enzyme. Analyte in a patient's serum competes with the analyte in the analyte-ED conjugate for antibody, modulating the amount of beta-galactosidase formed. The signal generated by enzyme substrates is directly proportional to the analyte concentrations in the patient's serum. We describe quick (5-15 min) colorimetric tests for digoxin, requiring no serum pretreatments or predilutions and suitable for use with centrifugal and random-access analyzers.
Four immunoassay methods and standards compared for measuring fibronectin.
Authors: Brubaker D B , Blick K E , Romine M 
Published: January 2020

Abstract
Several companies have developed commercial kits to measure plasma fibronectin rapidly and inexpensively with readily available laboratory equipment. In two of these kits (Cooper Biomedical and Boehringer-Mannheim) an immunoturbidimetric method is used. In a third kit (Biomedical Technologies, Inc.) an enzyme immunoassay method is used. To evaluate these commercial kits for fibronectin assay, we selected nephelometry as a comparison method for ranking the kits with regard to precision and accuracy. We also compared antibody and fibronectin cross reactivity. The antibodies from various manufacturers appear similar, but the fibronectin standards from different sources showed significant variation. Rate nephelometry and the Boehringer-Mannheim kit had the best within-run precision (CVs of 0.38% and 5.5% respectively). Between-run precision for nephelometry was excellent (CV = 1.9%) and somewhat high for the Boehringer-Mannheim kit (CV = 15.4%). This study demonstrates a need for further standardization of antigen (fibronectin) and antibody in commercial kits and the development of suitable stable quality-control material.
pK1' and bicarbonate concentration in plasma.
Authors: Flear C T , Roberts S W , Hayes S , Stoddart J C , Covington A K 
Published: January 2020

Abstract
Values for pK1' were determined from pH measured at 37 degrees C with three blood-gas analyzers and from calculated pco2 values in 443 freshly separated plasmas, tonometered at 37 degrees C. Plasma was taken from healthy volunteers, seriously ill patients, and hyponatremic patients. pK1' values varied by considerably more than 0.06 in healthy volunteers as well as in very ill patients, and bicarbonate concentrations ([HCO3]p) calculated by blood-gas analyzers based on the pK1' value of 6.1 could be in error by some +/- 60%. pK1' was similarly determined for tonometered (37 degrees C) replicate dilutions of plasma samples. By adding weighed amounts of dry NaCl and NaHCO3 to the diluted samples we increased the Na+ concentration to approximately 150 mmol/L and bicarbonate concentrations to values ranging from approximately 2.5 to approximately 52.5 mmol/L. pK1' values decreased when [HCO3]p was increased in dilutions of plasma kept at constant ionic strength. At any given [HCO3]p, pK1' values were higher at high than at low values of pco2.