bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clinical performance of a parathyrin immunoassay with dynamically determined reference values.
Authors: Lepage R , D'Amour P , Boucher A , Hamel L , Demontigny C , Labelle F 
Published: January 2020

Abstract
We compared the clinical performance of a carboxyl-terminal radioimmunoassay for human parathyroid hormone (iPTH), using either a dynamic reference interval (95% confidence limits of serum iPTH concentrations observed in 11 normal individuals during intravenous infusions of Na2EDTA and CaCl2) or a gaussian (2 SD) reference interval derived from 233 normocalcemic individuals. The 2 SD ranges were 3.5 to 9.8 pmol/L for serum iPTH and 2.19 to 2.53 mmol/L for total calcium. The iPTH dynamic interval was lower for calcium concentrations greater than 2.50 mmol/L; it was higher, wider, and continued to increase for calcium values less than or equal to 2.25 mmol/L. Use of the dynamic reference interval increased the clinical sensitivity of our assay from 81% and 61% to 100%, respectively, in primary hyperparathyroidism (n = 47) and hypoparathyroidism (n = 18). Test specificity was maintained at 100% in hypocalcemic disorders but fell to 93% (62/67) in hypercalcemic disorders. Overall, use of the dynamic reference interval improved the assay performance.
Activities of creatine kinase and its isoenzymes in serum in various skeletal muscle disorders.
Authors: Arenas J , Diaz V , Liras G , Gutierrez E , Santos I , Martinez A , Culebras J M 
Published: January 2020

Abstract
We studied possible correlations between anatomopathological and clinical features and the values for total creatine kinase (CK; EC 2.7.3.2) and its isoenzymes, including the proportion of CK-MB, in a population displaying several neuromuscular pathologies. Although we observed no specific isoenzyme pattern associated with the different myopathies, we found isoenzyme analysis useful in studying the histopathological evolution of illness. We also considered whether the pathology was regenerative or nonregenerative, and what type of fiber (I or II) was involved. High CK-MB percentages (greater than 6%) were associated with regenerative and type I fiber myopathies, with regenerative type tissues being the principal factor associated with an increasing proportion of CK-MB. Studying the changes in CK-MB percentage in serum appears to be useful in discriminating neuromuscular from myocardial pathologies.
Ferrochelatase activity in human lymphocytes, as quantified by a new high-performance liquid-chromatographic method.
Authors: Rossi E , Costin K A , Garcia-Webb P 
Published: January 2020

Abstract
We describe a new rapid, sensitive high-performance liquid-chromatographic (HPLC) method for determining ferrochelatase (EC 4.99.1.1) activity in lymphocytes. Zinc and mesoporphyrin are incubated aerobically with sonicated lymphocytes and the zinc mesoporphyrin formed is extracted with dimethyl sulfoxide-methanol-EDTA for quantification by HPLC. Incubation conditions, including the concentration of the palmitic acid activator, were optimized. The Michaelis constant (Km) was 2.1 mumol/L for mesoporphyrin, 22.2 mumol/L for zinc. The mean ferrochelatase activity (expressed as zinc mesoporphyrin formed per hour per milligram of lymphocyte protein) for a reference population was 3.25 (SD 0.43) nmol.h-1.mg-1. For three patients with erythrohepatic protoporphyria (EHP), activities were 1.11, 1.30, and 1.35. Neutrophils contain negligible ferrochelatase activity.
Exponential function for calculating saturable enzyme kinetics.
Authors: Keller F , Emde C , Schwarz A 
Published: January 2020

Abstract
Enzyme kinetics are usually described by the Michaelis-Menten equation, where the time-dependent decrease of substrate (-dS/dt) is a hyperbolic function of maximal velocity (Vmax), Michaelis constant (Km), and amount of substrate (S). Because the Michaelis-Menten function in its most general meaning requires an assumption of steady-state, it is less curvilinear than true enzyme kinetics. A saturation-type exponential function is more curvilinear than the hyperbolic function and more closely approximates enzyme kinetics: -dS/dt = Vmax [1 - exp(-S/Km)]. The mathematical representation of enzyme kinetics can be further improved by introducing a deceleration term (Vdec), to make the assumption of a steady state unnecessary. For the action of chymotrypsin on N-acetyltyrosylethylester, the Michaelis-Menten equation yields the following: Vmax = 3.74 mumol/min and Km = 833 mumol. According to decelerated enzyme kinetics, the values Vmax = 4.80 mumol/min, Vdec = 0.0118 mumol/min, and the association constant (Ka) = 0.00111/mumol are more nearly accurate for this reaction (where 1/Ka = 901 mumol approximately Km).
Liquid-chromatographic quantification compared with gas-chromatographic-mass-spectrometric determination of verapamil and norverapamil in plasma.
Authors: Hynning P A , Anderson P , Bondesson U , Boréus L O 
Published: January 2020

Abstract
A high-performance liquid chromatographic (HPLC) method for determining verapamil and norverapamil in plasma is presented and compared with gas chromatography/mass spectrometry (GC-MS). The plasma samples were extracted at alkaline pH with hexane containing 2-butanol (20 mL/L) and then back-extracted into phosphate buffer (0.1 mol/L, pH 3.0). For chromatography we used a reversed-phase column (Supelcosil LC-18 DB) with a mobile phase of the phosphate buffer and acetonitrile (70/30 by vol). Fluorescence detection was used (excitation at 203 nm, emission at 320 nm). Overall analytical recovery was 85%. Standard curves were linear from 1 to 1000 micrograms/L. The detection limit was 1 microgram/L. The assays are accurate and precise. We found no interferences by those substances tested. Results by HPLC and GC-MS agreed well (r = 0.99) for both verapamil and norverapamil determinations.
Fully automated liquid-chromatographic determination of amino acids.
Authors: van Eijk H M , van der Heijden M A , van Berlo C L , Soeters P B 
Published: January 2020

Abstract
This inexpensive method for fully automated amino acid analysis combines the advantages of automated precolumn derivatization with o-phthaldialdehyde and favorable analytical conditions to separate and quantify 30 amino acids found in normal plasma. The system can run unattended for almost four days, during which the data are processed automatically by a personal computer and a maximum of 76 samples and 19 standards can be processed (cycle time per analysis: 55 min). Only 1 microL of deproteinized plasma is required per analysis. Coefficients of variation for retention times and areas measured for all relevant amino acids are less than 1% and 3%, respectively. The system described is well suited for quick, sensitive operation in daily practice.
Influence of strenuous exercise on albumin excretion.
Authors: Krämer B K , Kernz M , Ress K M , Pfohl M , Müller G A , Schmülling R M , Risler T 
Published: January 2020

Abstract
Renal albumin excretion rate was 7.3 mg/24 h (SEM 0.5, range 0.6-21.0) in 66 healthy subjects. This rate increased markedly during and shortly after strenuous exercise on a bicycle ergometer (before: 5.5 +/- 0.6 micrograms/min; during and just after: 16.9 +/- 2.2 micrograms/min; P less than 0.001; n = 30). However, albumin excretion/24 h was not significantly higher during 24 h with a period of strenuous exercise than during 24 h without such exercise (10.3 +/- 0.9 mg/24 h vs 8.5 +/- 0.7 mg/24 h).
Applicability of the Ektachem 400 analyzer for assaying analytes in miscellaneous body fluids.
Authors: Georgewill D A , Graham G A , Schoen I 
Published: January 2020

Abstract
The Ektachem analyzer, a slide-film chemistry technology, demonstrated applicability to non-serum, non-urine stimulated and actual clinical specimens having a wide range of protein concentration and pH. The simulated specimens studied had pH and protein that ranged from 2 to 9 and 0 to 88 g/L, respectively. Actual patients' specimens studied, which had protein concentrations ranging from 0.1 to 60 g/L, included peritoneal fluid, vitreous fluid, synovial fluid, pericardial fluid, and cerebrospinal fluid. The analytes studied included glucose, urea nitrogen, uric acid, creatinine, calcium, phosphorus, sodium, potassium, chloride, and carbon dioxide.
Determination of manganese in biological materials by electrothermal atomic absorption spectrometry: a review.
Authors: Baruthio F , Guillard O , Arnaud J , Pierre F , Zawislak R 
Published: January 2020

Abstract
The great diversity of methods for measuring manganese in biological materials (serum, plasma, whole blood, urine, spinal fluid, and hair) reflects the difficulty in measuring extremely small quantities of this element. Detailed examination of these methods demonstrates that the one most used is flameless atomic absorption spectrometry. In this review we report the different instrument settings for wavelength, slit width, protection gases, graphite furnaces, type of background correction, amounts measured, and thermal programs. We give detailed recommendations by various authors for collecting samples. A thorough description of the preliminary steps and the handling of the specimen samples is also included: direct determination with or without dilution, addition of a matrix modifier or determination after ashing, with or without chelation-extraction steps. The preparation of the standards, procedures used, analytical criteria (accuracy, precision, specificity, detection limit, linearity), problems (interferences, matrix effects), and reference values and their physiological variations are also described. We give a consensus of recommendations concerning the choice of a method.
"Sandwich"-type immunoassay of carcinoembryonic antigen in patients receiving murine monoclonal antibodies for diagnosis and therapy.
Authors: Primus F J , Kelley E A , Hansen H J , Goldenberg D M 
Published: January 2020

Abstract
Measurements of carcinoembryonic antigen (CEA) in blood increased dramatically in some patients who were receiving injections of monoclonal antibody. CEA titers were measured with a monoclonal antibody-based double-determinant enzyme immunoassay in which untreated plasma specimens were diluted with an equal volume of buffer containing mouse serum. Increasing CEA titers were accompanied by the appearance and coincident increase in titers of human antibody against mouse Ig (HAMA). Adsorption of these sera with solid-phase anti-human IgG or Protein A restored antigen titers to pretreatment values; evidently the serum factor eliciting false-positive CEA titers was most probably HAMA. Neither addition of undiluted mouse serum to the assay mixture nor pretreatment by heating plasma specimens to 70 degrees C effectively abolished HAMA interference. By contrast, protein precipitation with polyethylene glycol (130 g/L) or heating plasma samples to 90 degrees C eliminated false-positive titers caused by HAMA, but did not reduce authentic CEA titers.
Preliminary tests for drugs of abuse.
Authors: Sunshine I 
Published: January 2020

Abstract
A drug-testing program must be designed by the client in consultation with the laboratory. The test procedures selected for the analytes in question depend on the defined "cutoff" concentrations, equipment available, and turnaround time. Preliminary tests are needed to separate the large number of negatives from presumptive positives, which then have to be confirmed. Immunoassays done with random-access analyzers are the procedures of choice. In clinical situations, thin-layer chromatographic procedures may be favored. The attributes and liabilities of the various procedures are presented as guides to the selection of a suitable procedure for a particular client.
What is the cause of benign transient hyperphosphatasemia? A study of 35 cases.
Authors: Crofton P M 
Published: January 2020

Abstract
In a study of 35 children with benign transient hyperphosphatasemia, I found a marked seasonal clustering of cases after the summer months. Furthermore, plasma 25-hydroxyvitamin D concentrations were almost twice those of controls matched for age and time of year. Many children had evidence of weight loss and one had idiopathic hypercalcemia of infancy. Activities both of liver and bone isoenzymes of alkaline phosphatase (EC 3.1.3.1) in plasma were increased. The liver and (to a lesser extent) bone isoenzymes had enhanced electrophoretic mobility, and both showed increased binding to wheat-germ lectin by affinity electrophoresis. For the liver (and probably also the bone) isoenzyme, these changes were due to an increased content of sialic acid. A possible etiology for the condition is proposed involving (a) increased synthesis of alkaline phosphatase, mediated by vitamin D metabolites, and (b) decreased hepatic clearance caused by the high sialic acid content and exacerbated in some cases by the effects of some drugs on the liver.
Rapid evolution in the immunochemical findings of a gamma heavy chain disease.
Authors: Pontet F , Gué X , Dosquet C , Caen J , Rousselet F 
Published: January 2020

Abstract
We noted the following major immunochemical changes in the final course of a gamma heavy-chain disease associated with a myelomonocytic leukemia: an important oligoclonal increase of IgG1/kappa, during sepsis development, whereas the lambda molecules decreased and IgG2 and IgG3 completely disappeared in a one-month interval. Initial concentrations of IgG4 were stable during that period, and gamma 1 heavy chains were slightly increased. This is a very unusual observation of the successive immunochemical events terminating a gamma heavy-chain disease.
Trace elements in human clinical specimens: evaluation of literature data to identify reference values.
Authors: Iyengar V , Woittiez J 
Published: January 2020

Abstract
Reference values are proposed for the concentrations of As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Pb, Se, and Zn in whole blood, blood serum, urine, milk, liver, and hair from adult human subjects. For F, I, and Ni, it was not possible to evaluate reference intervals for all the specimens mentioned above. For several elements, including Al, B, Br, Cs, Li, Rb, U, and V, the present status of the literature does not provide an adequate basis for formulating baseline concentrations; therefore, results from selected investigations are listed for information only. For elements such as Cu, Fe, and Zn, which are known to be homeostatically controlled, the concentrations in whole blood and blood serum follow a gaussian-like frequency distribution, and we could consider both median and mean values for evaluation. On the other hand, elements whose concentrations in tissues and body fluids are influenced by dietary availability (e.g., As and Se) or environmental factors (e.g., Cd, Hg, and Pb) show wide scatter. In these cases, the median appeared to be a better indicator of the central tendency than the mean, when different populations are involved. These points are illustrated.
Preparation of monoclonal antibodies reactive with beta-1,2-linked oligomannosyl residues in the phosphomannan-protein complex of Candida albicans NIH B-792 strain.
Authors: Tojo M , Shibata N , Kobayashi M , Mikami T , Suzuki M , Suzuki S 
Published: January 2020

Abstract
Hybridomas obtained by fusing the spleen cells of BALB/c female mice hyperimmunized with heat-killed yeast-form cells of Candida albicans NIH B-792 strain and a mouse myeloma cell line, P3X63Ag8.653, produced antibodies to beta-1,2-linked oligomannosyl residues in the phosphomannan-protein complex of the parent cells. Most of these monoclonal antibodies were IgM, but about 10% of the hybridomas produced IgG1 immunoglobulins. Ascites fluid from BALB/c mice inoculated with an IgG1-producing hybridoma showed different precipitability with the phosphomannan-protein complexes of three representative C. albicans strains, with NIH B-792 (serotype B) greater than NIH A-207 (serotype A) greater than J-1012 (serotype A, formerly serotype C). In contrast, a rabbit polyclonal antiserum to C. albicans NIH B-792 cells was unable to distinguish these same complexes. This ascites fluid agglutinated the heat-killed cells of three Candida strains, but not those of three others or of Torulopsis glabrata IFO 0622. The other ascites fluids, containing antibodies of the IgM class, agglutinated cells from three C. albicans strains and also C. tropicalis IFO 0587 cells.
Cerebrospinal fluid IgG and IgM indexes as indicators of active neurosyphilis.
Authors: Hische E A , Tutuarima J A , Wolters E C , van Trotsenburg L , van Eyk R V , Bos J D , Albert A , van der Helm H J 
Published: January 2020

Abstract
Serological and non-serological tests were performed in matched samples of cerebrospinal fluid and serum from 236 syphilitic patients. An increased IgG or IgM index, or both, was found about 70 times more often in symptomatic neurosyphilis than in latent syphilis without involvement of the central nervous system. An increased Ig index, together with a cell count greater than 5/microL, was only found in symptomatic neurosyphilis. Although the numbers of data are small, we conclude that the IgG and IgM indexes are valuable tests in the diagnosis of syphilitic involvement of the central nervous system.
Plasma and urinary taurine in epilepsy.
Authors: Collins B W , Goodman H O , Swanton C H , Remy C N 
Published: January 2020

Abstract
A previous study showed that significantly less taurine is excreted in the urine by epileptics than by control subjects. The difference is ascribed to genetic variation in taurine transport governed by a pair of codominant polymorphic alleles. The present study of plasma taurine concentrations and urinary taurine output confirms previous findings among epileptics and provides evidence that some anticonvulsant medications may affect taurine transport. The posited codominant alleles represent the first single-locus component in the polygenic complexes creating susceptibility to seizures and epitomizes the small additive effects classically attributed to such genes.
Rapid equilibrium radioimmunoassay for the amino-terminal propeptide of human type III procollagen.
Authors: Risteli J , Niemi S , Trivedi P , Mäentausta O , Mowat A P , Risteli L 
Published: January 2020

Abstract
This is an equilibrium-type radioimmunoassay for the amino-terminal propeptide of type III procollagen (PIIINP), which overcomes the problem of nonparallelism between the standard and human serum samples encountered with earlier assays. Proper selection of antiserum and reaction conditions diminishes interference from degradation products of the propeptide in serum. Because a rapid solid-phase-bound second-antibody step is included, the assay takes only 3 h. The intra-assay and the interassay CVs are both about 5%. In infants and children the concentration of PIIINP in serum closely parallels the growth-velocity curve. For 88 presumably healthy adults, the PIIINP concentration was 1.7-4.2 micrograms/L, about a third that measured with the previously available commercial assay. This is because of lack of inhibition by small Col 1 domain-related degradation products.
A high-performance liquid-chromatographic method for routine simultaneous determination of nicotine and cotinine in plasma.
Authors: Hariharan M , VanNoord T , Greden J F 
Published: January 2020

Abstract
We describe a rapid, sensitive method for the routine simultaneous determination of nicotine and cotinine in 1 mL of plasma. Extraction in 10-mL screw-capped Teflon tubes with methylene chloride after deproteinization with trichloroacetic acid eliminated emulsion formation. The extract, after evaporation and reconstitution in 30 microL of mobile phase, is injected into a reversed-phase C-18 ion-pair column of an isocratic high-performance liquid-chromatographic unit. Absorbance is monitored at 256 nm. The mobile phase is a citrate-phosphate (30 mmol each per liter) buffer mixture containing 50 mL of acetonitrile and 1 mmol of sodium heptanesulfonate per liter. 2-Phenylimidazole is the internal standard. The detection limit is 1 microgram/L for nicotine and 3 micrograms/L for cotinine. The standard curve is linear from 0 to 700 micrograms/L for both compounds. The average CV for nicotine in the concentration range 0-100 micrograms/L is 6.5%, and that for cotinine in the concentration range 50-700 micrograms/L is 4%.
Oligoclonal bands in cerebrospinal fluids: significance of corresponding bands in serum for diagnosis of multiple sclerosis.
Authors: Davenport R D , Keren D F 
Published: January 2020

Abstract
Controversy exists regarding the definition of oligoclonal bands in cerebrospinal fluid (CSF) and whether CSF bands with corresponding bands in the serum should be disregarded in the interpretation. Much of this controversy results from not distinguishing between the sensitivities of different techniques used for these studies. Because the combination isoelectric focusing/silver staining is more sensitive than agarose gel electrophoresis/Coomassie Blue staining for detecting weak bands, one would expect to find weak oligoclonal bands in the serum more frequently with the former technique than the latter. Yet, most clinical laboratories use agarose gel electrophoresis for this assay. To investigate the clinical relevance of CSF oligoclonal bands as compared with corresponding bands for serum by electrophoresis on agarose gel, we retrospectively reviewed paired CSF and serum electrophoretograms of 104 patients. We determined that the specificity of the oligoclonal-band test for diagnosis of multiple sclerosis was significantly enhanced by running paired CSF and serum specimens when CSF bands with corresponding serum bands were discounted.
Erroneous results with routine laboratory testing for immunoglobulins due to interference from circulating immune complexes in a case of hyperviscosity syndrome associated with autoimmune disease.
Authors: Levinson S S , Perry M , Goldman J , Nathan L E 
Published: January 2020

Abstract
A patient with the hyperviscosity syndrome exhibited very high concentrations of intermediate to small circulating immune complexes (CIC), involving 40-50% of the IgG present, with IgG rheumatoid factor activity. We demonstrate that precipitation of CIC by polyethylene glycol in the reaction mixture caused interference with nephelometric methods for measuring IgM and IgA, and that failure of immunoglobulins to migrate, owing to molecular interactions, caused interference with radial immunodiffusion methods. Semiquantitative values for immunoglobulins were difficult to interpret on immunoelectrophoresis. As a result, IgM and IgA could only be quantitatively estimated by an end-point nephelometric approach that included a serum blank. Immunoelectrophoresis indicated that a large proportion of the immunoglobulins behaved as aggregates. Immunofixation electrophoresis did not reveal the presence of aggregates. The polyethylene glycol-IgG test provided an accurate assessment of the CIC concentration; the Raji cell and C1q-binding assays did not. Evidently, special techniques may be necessary for accurate determination of immunoglobulin concentrations when CIC concentrations are very high.