bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assay of Urinary Free Fucose by Fluorescence Labeling and High-Performance Liquid Chromatography
Authors: Suzuki J , Kondo A , Kato I , Hase S , Ikenaka T 
Published: January 2020

Abstract
The concentrations of free fucose and other sugars in urine of cancer patients and healthy subjects were analyzed by high-performance liquid chromatography. After the urine samples were dried, we coupled the sugars in the residue with 2-aminopyridine to be detected as fluorescent derivatives. We then analyzed the pyridylamino derivatives of the sugars with an anion-exchange column and borate buffer. The difference between cancer patients and healthy subjects for the mean concentrations of fucose corrected for creatinine was significant (P less than 0.001). We checked the relationship between the concentrations of other sugars and the presence of cancer. This method is highly sensitive, and neither a cleanup procedure before labeling nor purification before injection into the column is needed. Not only fucose but also other sugars can be detected simultaneously, so this method should be useful for studying any changes in sugars in urine in various diseases.
Nonisotopic Binding Assay for Measuring Vitamin B12 and Folate in Serum
Authors: van der Weide J , Homan H C , Cozijnsen-van Rheenen E , Vivié-Kipp Y , Poortman J , Kraaijenhagen R J 
Published: January 2020

Abstract
We evaluated a nonisotopic method (CEDIA; cloned enzyme donor immunoassay) for estimating vitamin B12 and folate in serum. The assays were performed with a Cobas-Mira analyzer. Intra-assay CVs were from 3.7% to 11.0% for vitamin B12 and from 1.2% to 10.7% for folate. Interassay CVs ranged from 9.5% to 11.9% for vitamin B12 and from 6.1% to 18.5% for folate. Linearity was satisfactory, with analytical recovery of 94% at 8.7 and 25.4 nmol/L for folate and 280 and 554 pmol/L for vitamin B12. The detection limit was 3.6 nmol/L for folate and 12.3 pmol/L for vitamin B12. Results of this assay correlated well with those of a conventional radioassay: r = 0.98 for vitamin B12 (n = 51) and r = 0.97 for folate (n = 57). The CEDIA was easy to perform but appeared to be unreliable for use with samples from myeloma patients.
Establishment of an External Quality-Assessment Scheme for Amino Acid Analyses: Results from Assays of Samples Distributed during Two Years
Authors: Rattenbury J M , Tewnsend J C 
Published: January 2020

Abstract
Vol. 36
p. 224: In the caption for Figure 1, the curves should be identified as follows: A, *; B, +; and C, •.
p. 371: Left column, line 10, should refer to women, not men. Right column, third line above the Statistics section, should note that results were read at 450 nm (with a reference wavelength of 630 nm). In Table 2, INN prefix refers to Innsbruck monoclonal antibodies.
p. 373: Right column, line 9, should read: however, only the hCG/free-α ratio was significantly different between progressive and nonprogressive tumors (P&lt;0.05). The Figure 5 subcaption, first sentence, should read: Serum concentrations exceeding the physiological ranges of the three markers (mean serum values for healthy men plus 3 SD; 99.7% confidence interval) were defined as positive for those markers.
p. 374: Right column, line 12, should read: suppression of free-α secretion by an LHRH antagonist.
Measuring Urinary Glycosaminoglycans in the Presence of Protein: An Improved Screening Procedure for Mucopolysaccharidoses Based on Dimethylmethylene Blue
Authors: de Jong J G , Wevers R A , Liebrand-van Sambeek R 
Published: January 2020

Abstract
Earlier we described a simple and reliable screening procedure in urine for mucopolysaccharidoses based on the color reaction of glycosaminoglycans (GAGs) with dimethylmethylene blue. At physiological concentrations of urinary protein, we observed an obvious interference by protein in the assay. By modifying the assay, we abolished the protein interference. The modified procedure is not disturbed by human serum albumin, IgG (both tested with as much as 5 g/L of protein), or urinary proteins. The modified procedure appeared as reliable as the original. No false-negative results were found in a series of 26 urine samples from patients with mucopolysaccharidoses (sensitivity 100%). In a series of 405 urine samples offered for metabolic screening, 24 samples with increased GAG content and normal GAG composition were seen (specificity 94%). The method may also be applicable for determining GAG in other body fluids or solutions containing protein.
Effects of Albumin and Immunoglobulin A on Fructosamine Assay
Authors: Singh J , Kulig K A 
Published: January 2020

Abstract
Serum fructosamine, albumin, and IgA were measured in three groups of human subjects: 54 nondiabetic normal individuals, 149 nondiabetic patients, and 149 diabetic patients. Normal subjects had significantly (P less than 0.05) higher fructosamine (2.91, SD 0.33, mmol/L) than did nondiabetic patients (2.49, SD 0.46, mmol/L). Each of these groups had significantly (P less than 0.05) lower fructosamine than did diabetic patients (3.76, SD 1.16, mmol/L). Increased fructosamine appeared to be associated with increases in both albumin and IgA. However, fructosamine was significantly (P less than 0.05) correlated with neither albumin nor IgA in the normal group, with only albumin in the nondiabetic group, but with both albumin and IgA in the diabetic group. Selective combinations of these populations not only shifted these significances but also eliminated some of the correlations. Our results suggest caution regarding the diagnostic role and universality of fructosamine and of its correlation with IgA as indicated by others.
Biological Variability of Lipoproteins and Apolipoproteins in Patients Referred to a Lipid Clinic
Authors: Kafonek S D , Derby C A , Bachorik P S 
Published: January 2020

Abstract
We determined the physiological variability of total cholesterol, high- (HDL) and low-density lipoprotein (LDL) cholesterol, triglycerides, and apolipoproteins A-I and B in fasting blood samples from patients referred to the Johns Hopkins Lipid Referral Clinic. Samples were taken on each of three occasions during baseline evaluation visits before the patients were treated. The median physiological coefficients of variation (CVp) were as follows: total cholesterol, 5.0%; triglycerides, 17.8%; HDL cholesterol, 7.1%; LDL cholesterol, calculated from the previous three measurements, 7.8%; and apolipoproteins A-I and B, 7.1% and 6.4%, respectively. There were no significant differences in CVp between children (less than or equal to 18 years) and adults (greater than 18 years) for any of the measurements. On the basis of our findings, single measurements in serial samples taken on three occasions suffice to establish the patients' usual values with the following precisions (+/- 1 CV): total cholesterol, +/- 4%; triglycerides, +/- 11%; HDL cholesterol, +/- 8%; LDL cholesterol, +/- 6%; and apolipoproteins A-I and B, +/- 7%.
Dynamic Relation between Reduced, Oxidized, and Protein-Bound Homocysteine and Other Thiol Components in Plasma During Methionine Loading in Healthy Men
Authors: Mansoor M A , Svardal A M , Schneede J , Ueland P M 
Published: January 2020

Abstract
We used a newly developed procedure to determine reduced, oxidized, and protein-bound forms of homocysteine, cysteine, cysteinylglycine, and glutathione to measure the plasma concentrations of these species during methionine loading in six young healthy men with normal fasting concentrations of plasma homocysteine and cysteine. The methionine loading induced a transient increase in total homocysteine, which peaked after approximately 6-8 h. All six subjects showed a concurrent significant increase in reduced homocysteine and cysteine, which peaked 2 h after loading, and a rapid decrease in protein-bound cysteine and cysteinylglycine. The concentration of reduced cysteinylglycine was not altered. Plots of protein-bound cysteine and cysteinylglycine vs total homocysteine formed hysteretic loops, showing a time-dependent relation between these analytes. After the initial decrease, protein-bound cysteine and cysteinylglycine showed a slight, transient increase. From 12 to 24 h after loading, protein-bound cysteine approached preloading concentrations in two subjects and declined further in four subjects. The response pattern was similar for cysteine and cysteinylglycine in each subject. Simple displacement could not account for these effects, which suggests that plasma homocysteine may affect the disposition of other thiols through complex mechanisms. The presence of reduced homocysteine and the dynamic relation that exists between homocysteine, cysteine, and related compounds in plasma should be taken into account when evaluating plasma homocysteine as an indicator or causative agent of human disease.
Temperature Effects on Free-Thyroxine Measurements: Analytical and Clinical Consequences
Authors: van der Sluijs Veer G , Vermes I , Bonte H A , Hoorn R K 
Published: January 2020

Abstract
We compared the analytical and clinical performance of two free-thyroxine (FT4) assays--a solid-phase radioimmunoassay, Spectria, and a time-resolved fluoroimmunoassay, Delfia, both of them two-step methods--with the performance of a direct radioimmunoassay, Nichols, to measure FT4 concentration in equilibrium dialysate of undiluted serum. The three assays showed comparable analytical performance. We tested clinical utility in sera from 135 healthy subjects with and without thyroxine-binding abnormalities and in 61 patients with and without thyroidal illnesses. We found significant differences for FT4 measured by different assays in sera from the same euthyroid patients. To explain the differences, we studied the influence of temperature on performance and calibration. Most important was the neglected fact that the association constant for the binding of thyroxine to thyroxine-binding globulin decreases when the temperature rises from 20 to 37 degrees C, causing a doubling of FT4. The two-step assays, if performed at room temperature without a well-defined calibration, can give misleading FT4 concentrations. This is the case when sera from patients with thyroxine-binding abnormalities are measured against kit standards, made up in normal human sera. If an assay is to reflect the in vivo FT4 concentration at body temperature in all types of samples, it should be performed at body temperature. For practical reasons 37 degrees C is recommended, and reference values should be defined at 37 degrees C. The same might be valid for other free-hormone assays.
Interassay Variability of Immunometric Methods for Thyrotropin in an External Quality Assessment Survey: Evidence that Functional Sensitivity is not Always Adequate for Clinical Decisions
Authors: Pilo A , Zucchelli G C , Malvano R , Clerico A , Iervasi G , Signorini C 
Published: January 2020

Abstract
We investigated the ability of current immunometric methods for thyrotropin (TSH; thyroid-stimulating hormone) to distinguish between low-normal and subnormal hormone concentrations by using the data from an external quality assessment (EQA) survey in 1990. We computed the interassay (between-run) precision profiles from results from 101 laboratories, which used the five most popular kits in the survey; during the control period (one year) each laboratory assayed 4 EQA pools distributed (as hidden replicates) in five occasions. The interassay CV was relatively low (9-13%) for three pools in the normal TSH range (greater than 0.8 milli-int. unit/L) but markedly higher (30-40%, except for one more precise kit) in the subnormal range (0.2 milli-int. unit/L). We calculated the effect of the between-run variability on the diagnostic accuracy (discrimination between normal and subnormal values) for three representative TSH concentrations: 0.2, 0.4, and 0.5 milli-int. unit/L (0.3 milli-int. unit/L was considered the lower normal limit). The three concentrations were reasonably discriminated (P less than or equal to 5%), and only one kit showed a between-run CV less than 18% at 0.2 milli-int. unit/L. For the other four less-precise kits, only the higher TSH value (0.5 milli-int. unit/L) could be classified with an acceptable diagnostic reliability. With the most precise kit, one can distinguish two TSH concentrations in the 0.3-0.5 milli-int. unit/L range that differ by at least 30%; with the other kits, differences greater than 50-60% are needed for reliable discrimination. Thus many laboratories fail to achieve the functional sensitivity of a second-generation assay, even if they use immunometric methods. TSH assays with a better interassay precision in the low concentration range are needed.
Multicenter Technical and Clinical Evaluation of a Fully Automated Enzyme Immunoassay for CA 125
Authors: Kenemans P , Bon G G , Kessler A C , Verstraeten A A , van Kamp G J 
Published: January 2020

Abstract
The technical performance and clinical usefulness of the newly developed Enzymun-Test CA 125 (Boehringer Mannheim) was evaluated in a multicenter study. Sera tested were obtained from healthy control subjects (n = 1003) and from patients with benign conditions (379), ovarian cancer (518), or other malignancies (479). Intra- and interassay variability was low at CA 125 concentrations greater than 100 units/mL. Intra- and interassay CVs were respectively less than or equal to 36% and 23% for the low CA 125 concentrations (less than or equal to 35 units/mL) and less than or equal to 15% and 14% for the medium CA 125 concentrations (36- less than or equal to 100 units/mL). Interlaboratory reproducibility of the Enzymun-Test CA 125 was excellent. A strong linear correlation was observed between Enzymun-Test CA 125 and three of four other commercially available assays of CA 125 in serum. Cutoff values of 35 units/mL in three of these other tests corresponded to Enzymun-Test CA 125 values ranging from 27.0 to 42.1 units/mL. In the fourth test, an enzyme immunoassay, a cutoff of 35 units/mL corresponded to Enzymun-Test values ranging from 64.1 to 77.0 units/mL. Discordant, as yet unexplained, results in which Enzymun-Test values were greater than 65 units/mL and Centocor CA 125 immunoradiometric assay results were less than 35 units/mL were found in 15 of 1003 samples (1.5%) of apparently healthy control subjects. Sensitivity and performance of the Enzymun-Test were very similar to those of the Centocor assay for sera from the patients with various benign disorders or malignant diseases. Given its excellent automated technical performance, this new CA 125 serum assay is feasible for monitoring ovarian cancer patients. Test results are interchangeable with those from other laboratories and, in general, with those obtained by most other CA 125 tests.
Comparison of Plastic vs. Glass Evacuated Serum-Separator (SSTTM) Blood-Drawing Tubes for Common Clinical Chemistry Determinations
Authors: Hill B M , Laessig R H , Koch D D , Hassemer D J 
Published: January 2020

Abstract
We evaluated a plastic evacuated blood-drawing tube containing an integral serum-separating barrier gel, by direct comparison with a glass counterpart. The plastic tube demonstrated no differences when compared for common clinical chemistry analytes with multiple types of instruments and systems. A total of 260 such different combinations were studied with emphasis on tests sensitive to drawing and handling indexes such as lactate dehydrogenase and potassium. A total of six separate blood drawings were tested with no significant differences noted in these tests. The total study included subjective evaluations of the plastic tube's use as a blood-drawing device and objective studies based on quantitative test results from normal and hospitalized patients and use of the primary sampling tubes (both plastic and glass) for 48-h storage.
Pulse Oximetry: Theory and Applications for Noninvasive Monitoring
Authors: Mendelson Y 
Published: January 2020

Abstract
Noninvasive measurement of arterial oxygen saturation (SaO2) by pulse oximetry is widely acknowledged to be one of the most important technological advances in monitoring clinical patients. Pulse oximeters compute SaO2 by measuring differences in the visible and near infrared absorbances of fully oxygenated and deoxygenated arterial blood. Unlike clinical blood gas analyzers, which require a sample of blood from the patient and can provide only intermittent measurement of patient oxygenation, pulse oximeters provide continuous, safe, and instantaneous measurement of blood oxygenation. Here I review the theoretical background behind this advanced technology, instrumentation requirements, practical instrument calibration, common features of commercial pulse oximeters, specific clinical applications, and performance limitations of pulse oximeters.
Development of a Proton Nuclear Magnetic Resonance Spectroscopic Method for Determining Plasma Lipoprotein Concentrations and Subspecies Distributions from a Single, Rapid Measurement
Authors: Otvos J D , Jeyarajah E J , Bennett D W , Krauss R M 
Published: January 2020

Abstract
We are developing a method for quantifying plasma lipoproteins by proton nuclear magnetic resonance (NMR) spectroscopy that offers advantages over existing clinical methods. We showed that the major lipoproteins have distinct NMR properties sufficient to permit their concentrations to be extracted from a computer lineshape analysis of the plasma lipid methyl resonance envelope (Clin Chem 1991; 37:377-86). We have now discovered that the spectra of the subspecies within each lipoprotein class are different enough to influence the composite spectrum of that class and hence the spectrum of whole plasma. By including spectra representative of these subspecies as additional components in the lineshape-fitting analysis, a complete concentration profile of very-low-density, low-density (LDL), and high-density (HDL) lipoproteins plus the subspecies distributions within these classes can be simultaneously generated. A pilot study of 30 plasma samples of widely varied composition demonstrated good agreement between NMR-derived values and lipoprotein lipid concentrations and LDL and HDL subspecies distributions determined by gradient-gel electrophoresis.
Relationship Between Smoking Status and Serum Lipids in a Hyperlipidemic Population and Analysis of Possible Confounding Factors
Authors: Bruckert E , Jacob N , Lamaire L , Truffert J , Percheron F , de Gennes J L 
Published: January 2020

Abstract
The aim of our study was to estimate the potential relationship between smoking behavior and other coronary heart disease risk factors in 250 hyperlipidemic patients. We present data obtained through self-reporting of the number of cigarettes smoked per day, measurements of three tobacco markers, and data on dietary habits and lipid variables. We measured cotinine (by HPLC) and thiocyanate and used a recent colorimetric assay for the indirect evaluation of the nicotine metabolites in a single urine specimen. Mean values of nicotine metabolites, expressed as cotinine equivalents, were 6.7, 39.9, and 79.4 mumol/L, respectively, for nonsmokers, light smokers (7.7 cigarettes per day), and heavy smokers (25.8 cigarettes per day). We found that light smokers have higher concentrations of cotinine and nicotine metabolites in proportion to the number of cigarettes smoked per day than do heavy smokers. Thus, the simple colorimetric assay can accurately evaluate smoking status. Hyperlipidemia and smoking are linked by an intricate network of multiple relations. The concentration of high-density lipoprotein (HDL) cholesterol is lower in heavy smokers, and the concentrations of triglycerides and cholesterol are higher. The 0.11 mmol/L difference in HDL cholesterol between light and heavy smokers is close to the results of previous papers; however, when gender, dietary habits (including alcohol intake), and data on body mass index are included in a multiple regression analysis, there is no longer an association between HDL cholesterol concentrations and smoking status. Therefore, these different dietary habits may be confounding factors that partly explain the pattern of lipid variables.
Multivariate Statistical Modeling: Alternative Approach to Test Evaluation, Applied to Counting Reticulocytes by Flow Cytometry
Authors: Oosterhuis W P , Zwinderman A H , Modderman T A , Dinkelaar R B , van der Helm H J 
Published: January 2020

Abstract
We present a statistical path analysis model for the evaluation of two tests in the absence of a "gold standard" method. This model is applied to the evaluation of flow-cytometric and visual reticulocyte counting by using as the comparison method a combination of three hematological measurements: hemoglobin concentration (HGB), mean cellular volume (MCV), and erythrocyte density width (EDW). We assumed that, in general, a higher reticulocyte count is associated with a lower HGB value and with greater values for MCV and EDW. Applying this assumption and the statistical model, we demonstrated that flow cytometry was superior to visual reticulocyte counting in the low-value range studied. The path analysis model is potentially applicable in other cases where two tests are to be compared, and when no gold standard is available.
Analysis for Fully Oxidized Neopterin in Serum by High-Performance Liquid Chromatography
Authors: Rippin J J 
Published: January 2020

Abstract
Fully oxidized D-neopterin in serum can be measured by HPLC. Serum samples were preincubated with ferric nitrate/EDTA solution to remove any dihydroneopterin, which is unstable and may give spuriously high results because of its conversion to D-neopterin. Pterins were extracted onto solid-phase propylbenzenesulfonic acid minicolumns and eluted with a 1:5 (by vol) mixture of ammonia solution (308 g/L) in acetonitrile. Extracts were evaporated and then reconstituted in mobile phase (50 mL of methanol per liter of 50 mmol/L phosphate buffer, pH 6.2) before injection. Separation was performed with a 25-cm ODS2 column (particle size, 5 microns) at 32 degrees C with fluorescence detection (lambda ex 360 nm, lambda em 440 nm). The between-batch CV was 7.1% and 5.6% for neopterin concentrations of 21.7 and 67.3 nmol/L, respectively. The limit of detection was 0.75 nmol/L, and the mean recovery of the extraction procedure was 90% for neopterin and internal standard. Correlation with a radioimmunoassay (x) gave y = 0.99x + 0.64 (r = 0.970, Sy/x = 2.75). The method allows daily analysis of serum D-neopterin in small batches and is currently used to monitor patients undergoing bone-marrow transplant.
Influence of a Serotonin- and Dopamine-Rich Diet on Platelet Serotonin Content and Urinary Excretion of Biogenic Amines and Their Metabolites
Authors: Kema I P , Schellings A M , Meiborg G , Hoppenbrouwers C J , Muskiet F A 
Published: January 2020

Abstract
Using high-performance liquid chromatography and gas chromatography, we reevaluated the 24-h influence of a serotonin- and dopamine-rich diet on platelet serotonin and serotonin, 5-hydroxyindoleacetic acid (5-HIAA), and major catecholamine metabolites in the urine of 15 healthy adults. Although there were significant responses in urinary free serotonin and catecholamine metabolites, their concentrations did not exceed the upper limits of the reference ranges for any of the participants. For urinary 5-HIAA, pronounced effects were observed within 2-4 h. After 6-8 h, results for 11 participants exceeded the upper limit of the reference range. The median recovery of dietary serotonin as urinary 5-HIAA was 20% and subject to a large range (1-50%). There was no significant change in platelet serotonin. We conclude that, using specific analytical methods, no dietary restrictions need be imposed to diagnose catecholamine (metabolite)-producing tumors. For diagnosis of carcinoids on the basis of urinary 5-HIAA it is appropriate to completely abstain from serotonin-containing foods for greater than or equal to 12 h before testing. Platelet serotonin is a more sensitive marker for carcinoids that produce only small amounts of serotonin, and is unaffected by dietary serotonin.