bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid-chromatographic determination of beta 2-microglobulin, alpha 1-acid glycoprotein, and albumin in urine.
Authors: Turpeinen U , Koivunen E , Stenman U H 
Published: January 2020

Abstract
We report a reversed-phase "high-performance" liquid-chromatographic assay for beta 2-microglobulin, alpha 1-acid glycoprotein, and albumin in urine. The urine samples are chromatographed on a 15 X 3.2 mm C18-column with a solvent gradient between two mixtures: 1 mL of trifluoroacetic acid per liter of water and 1 mL of trifluoroacetic acid per liter of acetonitrile. The proteins are detected at 218 nm. The useful lower limit of sensitivity for quantification is 0.1 micrograms of each protein in 100-microliters injected samples, corresponding to 1 mg of protein per liter of urine. The linear measuring range extends from 0.1 to 100 micrograms of protein for each peak. Mean analytical recoveries ranged from 92 to 100%. The mean within-assay CV was 7.5%, the between-assay CV 15%. Comparison of results with those obtained by immunoturbidimetry and radioimmunoassay shows acceptable correlation. Reproducible and rapid with low operational cost, this method is suitable for use in routine screening and quantification of urinary proteins.
Use of immunoglobulin heavy- and light-chain measurements compared with existing techniques as a means of typing monoclonal immunoglobulins.
Authors: Whicher J T , Wallage M , Fifield R 
Published: January 2020

Abstract
Using automated measurements of kappa and lambda light chains and IgG, IgA, and IgM, we assessed the utility of the kappa/lambda ratio and the heavy chain/light chain ratio in characterizing monoclonal immunoglobulins previously identified by sensitive electrophoresis on agarose gel and typed by immunofixation or immunoelectrophoresis. We examined 348 selected samples, of which 165 contained monoclonal components, finding that 93.4% were detected and 89% correctly typed by this approach. Eight samples were shown to contain monoclonal light chains that were not visible as bands on electrophoresis but demonstrated abnormalities of the kappa/lambda or heavy chain/light chain ratio.
Enzyme immunoassay of angiotensin I and renin.
Authors: Scharpé S , Verkerk R , Sasmito E , Theeuws M 
Published: January 2020

Abstract
We developed a sensitive and specific heterogeneous enzyme immunoassay for measuring angiotensin I (AI) or renin (EC 3.4.99.19) activities. Linking AI under carefully controlled conditions by means of N-succinimidyl-3-(2-pyridyldithio)propionate to highly purified beta-D-galactosidase (EC 3.2.1.23) produced a well-defined conjugate in high yield. The procedure is simple and consists of three steps: (a) incubate 0.5 mL of plasma with 100 microL of inhibitor solution for 1 h to generate renin activity; (b) incubate this with labeled AI for 1 h at 37 degrees C; and (c) do a double-antibody precipitation. Bound beta-D-galactosidase activity is determined, with O-nitrophenyl-beta-D-galactoside as substrate, by measuring the liberated O-nitrophenol at 410-420 nm. The analytical range of the assay extends from 62.5 to 4000 ng/L, and renin activities so measured in plasma correlate well with those measured by an established radioimmunoassay (n = 35, r = 0.97, intercept -0.6, and slope 1.44).
Alkaline phosphatase isoenzymes in the plasma of preterm and term infants: serial measurements and clinical correlations.
Authors: Crofton P M , Hume R 
Published: January 2020

Abstract
Serial measurements of the bone and fetal intestinal isoenzymes of alkaline phosphatase (EC 3.1.3.1) in the plasma of 43 term and 43 preterm infants, from birth to six weeks later, indicate that the bone isoenzyme gradually increases over this period in both preterm and term infants fed with unsupplemented commercial formulas. Preterm babies given formula supplemented with calcium (with or without additional phosphate) had significantly lower bone isoenzyme activities for most of the study period. The concentrations of fetal intestinal isoenzyme increased, under the stimulation of milk feeding, from generally undetectable at birth to a peak during the first two weeks postpartum, and then declined. This increase was highly significantly negatively correlated with gestational age, the preterm infants having a much higher and more prolonged increase in this isoenzyme than did term infants. Unlike the adult isoenzyme, fetal intestinal alkaline phosphatase in plasma showed no relationship with blood group status.
Direct quantification of coproporphyrins and uroporphyrins in urine by derivative synchronous fluorescence spectroscopy.
Authors: Valcárcel M , Gómez Hens A , Rubio S , Petidier A 
Published: January 2020

Abstract
The second-derivative synchronous fluorescence spectroscopic technique is applied to the simultaneous and direct assay of coproporphyrins and uroporphyrins in human urine. This technique resolves the overlapping conventional spectra, obviating the need for pre-analysis sample separation techniques, and measurements can be made in a single scan. The amplitudes of the derivative peaks are linearly related to uroporphyrin (0.4 to 300 micrograms/L) and coproporphyrin (0.4 to 250 micrograms/L) concentrations. The detection limit for both porphyrins is 0.1 microgram/L. Analytical recoveries range between 98 and 101%. Within- and between-assay CVs are reported. Results for 24-h urine specimens correlated well with those obtained by an extraction-ion-exchange chromatography combined method. The proposed method is inexpensive and requires no sophisticated detection equipment.
Identification and analysis of nine metabolites of cyclosporine in whole blood by liquid chromatography. 2: Comparison of patients' results.
Authors: Lensmeyer G L , Wiebe D A , Carlson I H 
Published: January 2020

Abstract
We used a "high-performance" liquid-chromatographic assay [for parent cyclosporine (CsA) and nine metabolites] and a radioimmunoassay to detail the diversity of results among whole-blood samples from patients with transplanted organs. Heterogeneous populations of metabolites in samples collected just before the next dose of CsA were detected by HPLC, with CsA, M17, M1, or M8 predominating; M21, M203-218, MUNDF1, and M18 were detected in lesser amounts. Results by HPLC vs RIA for CsA or for individual metabolites vs CsA (or RIA) were diverse, with correlation coefficients (r) ranging from 0.058 to 0.933. RIA vs HPLC(sum of CsA + metabolites) gave the best comparison (slope = 0.931, y-intercept 14 micrograms/L, r = 0.933); but the scatter of data about the regression line remained significant (Sy/x = 132 micrograms/L). Most important, RIA/HPLC(CsA) vs HPLC(sum of metabolites) was remarkably poor (r = 0.222). A 12-h pharmacokinetic curve (for drug concentrations in a heart-transplant patient) displayed dissimilar times for peak concentrations of CsA and metabolites; each differed in the proportion (48% to 81% of peak concentration) eliminated from blood over the 12 h. These studies exemplify the utility of a more-inclusive, specific assay to monitor the diverse disposition of cyclosporines in patients and to demonstrate the errors associated with use of the RIA/HPLC ratio technique to predict metabolite concentrations.
Immunonephelometry of apolipoprotein B with a centrifugal analyzer.
Authors: Hanson N Q , LeGeault T S , Freier E F 
Published: January 2020

Abstract
We developed an automated immunonephelometric assay for the measurement of apolipoprotein B (apo B) with a light-scattering microcentrifugal analyzer. Pretreating specimens with a dilute solution of Tween 20 or triglyceride lipase decreased the nephelometric response of apo B. Polyethylene glycol is included in the reaction mixture, and the reaction is complete within 4 min. The method is precise (CV = 6.5%, mean = 0.68 g/L) and the standard curve is linear to an apo B concentration of 2.8 g/L. Lipemia does not interfere with the method if grossly lipemic specimens are centrifuged to remove chylomicrons.
An assessment of the use of fixed limits to characterize intralaboratory performance by proficiency testing.
Authors: Ehrmeyer S S , Laessig R H 
Published: January 2020

Abstract
Currently, proficiency-testing (PT) programs are expanding the use of fixed limits to evaluate interlaboratory performance. These limits are an attempt to relate total allowable intralaboratory analytical error and performance in a PT program. Fixed limits are a means of counteracting the effects of overly stringent performance requirements derived from the interlaboratory group mean and standard deviations (SD) achieved by today's very precise analytical systems. Our previously described computer model of a PT program is used to delineate the quantitative relationship between the magnitude of intralaboratory coefficient of variation (CV) and bias that is compatible with fixed interlaboratory limits of 5, 10, 15, and 20% relative error. However, fixed limits alone do not fully characterize intralaboratory performance. The efficiency, or the percentage of times a laboratory's PT results are required to fall within the fixed limit, also must be considered when criteria for PT performance are being set. For example, a 10% fixed limit and a 80% efficiency will allow laboratories having CV-bias combinations from 8%-0%, 7%-4%, etc., to pass PT. The use of a 95% efficiency will allow CV-bias combinations from 4.8%-0%, 3.5%-4%, etc., to pass PT. We give a figure that depicts all possible combinations for four fixed limits and six efficiencies.
Participation of peptide moieties in adhesive behavior of antigenic mannans of Candida albicans to the plastic microtiter plate in enzyme-linked immunosorbent assay.
Authors: Tojo M , Shibata N , Mikami T , Suzuki M , Suzuki S 
Published: January 2020

Abstract
We report our studies of the mechanism of the adhesion of mannans of Candida albicans NIH A-207 and C. albicans NIH B-792 strains to the surface of a polystyrene microtiter plate being utilized for enzyme-linked immunosorbent assay (EIA) of antigens of this pathogenic yeast species. This binding was manifested predominantly by the peptide moieties of the mannans forming hydrophobic bonds with the plastic molecule. Eliminating the peptide of each mannan by treating it with a hot aqueous alkaline solution of NaBH4 also eliminated color development in the EIA.
Effect of daylight on the reaction of thiols with Ellman's reagent, 5,5'-dithiobis(2-nitrobenzoic acid).
Authors: Walmsley T A , Abernethy M H , Fitzgerald H P 
Published: January 2020

Abstract
The reaction of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB, Ellman's reagent) with thiols is sensitive to daylight, in particular to ultraviolet radiation at wavelengths around 325 nm. Exposure to light at the absorbance maximum of the yellow product (the thionitrobenzoate ion) at 410 nm had no effect on the reaction. The light-sensitive species is apparently the DTNB, because a spectral-irradiation experiment showed that the wavelength of light that produced the maximum rate of absorbance change coincided with the peak absorbance of DTNB, and it was well separated from the thionitrobenzoate absorbance peak. Ascorbate is ineffective as a stabilizer and can produce an apparent increase in the rate of DTNB destruction. In a practical example we found the light interference to be severe when hydrolysis of propionylthiocholine by plasma cholinesterase (EC 3.1.1.8) was measured after a 20-min incubation. The apparent cholinesterase activity in clear glass or plastic tubes exposed to diffuse daylight could be decreased to 25% of the value obtained for samples in light-excluded tubes. We recommend the reaction be carried out in artificial room light, with total elimination of daylight, because window glass does not sufficiently attenuate 325-nm wavelength irradiation.
Assessment of magnesium status.
Authors: Elin R J 
Published: January 2020

Abstract
The adult human body contains approximately 24 g (1 mol) of magnesium--about half in bone and half in soft tissues. Only about 0.3% of the total body magnesium is present in serum, yet the majority of analytical data obtained is from this body fluid. Assessing the magnesium status of an individual is difficult, there being at present no simple, rapid, and accurate test to determine intracellular magnesium, but determination of total and free magnesium in tissues and physiological tests provide some information. Changes in magnesium status have been linked to cardiac arrhythmias, coronary heart disease, hypertension, and premenstrual syndrome. A better understanding of magnesium transport and of factors controlling magnesium metabolism is needed to elucidate the role of magnesium in disease processes.
Time-resolved immunofluorometric assay for the ovarian carcinoma-associated antigenic determinant CA 125 in serum.
Authors: Boerman O C , Thomas C M , Segers M F , Kenemans P , Lövgren T , Zurawski V R , Haisma H J , Poels L G 
Published: January 2020

Abstract
A time-resolved immunofluorometric assay (IFMA) is described for quantifying the ovarian carcinoma-associated antigenic determinant CA 125 in human serum. Monoclonal antibody to CA 125 is immobilized onto a microtiter well, and the same antibody labeled with a europium chelate is used as a tracer. After the immunoreaction the bound portion of the labeled antibody is quantified by dissociating the Eu3+ in a fluorescence-enhancement solution and measuring its fluorescence with a time-resolved fluorometer. The detection limit of the IFMA is 1.5 arb. units/mL, being about the same as that of a commercially available immunoradiometric assay (IRMA) for CA 125 (1.4 arb. units/mL). The analytical range of the IFMA extends to 2000 arb. units/mL, whereas the range of the IRMA is 500 arb. units/mL. For 29 serum samples from ovarian-cancer patients measured simultaneously in the IFMA and IRMA, orthogonal regression analysis gave the equation CA 125 (IFMA) = 0.9937 CA 125 (IRMA) - 1.211 arb. units/mL (Syx = 6.8681, r = 0.9932). Apparently, the IFMA for CA 125 is a convenient alternative to the IRMA for CA 125 because of short counting times, the use of nonradioactive, stable reagents, and the much-extended measuring range. Additionally, the microtiter format should lend itself to more fully automated procedures in laboratories doing many such analyses.
Chemical characterization of urinary glycopeptides.
Authors: Matsue H , Takagaki K , Honda K , Nakagawa Y , Gejyo F , Arakawa M , Endo M 
Published: January 2020

Abstract
We prepared human urinary glycopeptides from the supernatant liquid remaining after precipitation of the nondialyzable fraction with cetylpyridinium chloride. Using cation exchange and affinity chromatographies and gel filtration, we obtained 28 glycopeptide subfractions. By compositional analyses of sugar and amino acid, and by reducing-terminal analyses after reduction with NaBH4, we determined the size of the carbohydrate moiety and the types of carbohydrate-peptide linkage involved. We isolated several glycopeptides not previously described: six with sialic acid, two with fucose, two with glucose, and one with N-acetylgalactosamine. The sialic acid glycopeptides had a short carbohydrate chain of the O-glycoside type. The fucose-containing glycopeptides were fucosyllactosaminoglycans. The glucose glycopeptides were polymers linked to a small peptide moiety. The N-acetylgalactosamine-rich glycopeptide was found in an N-glycoside-type fraction, with N-acetylgalactosamine at the nonreducing terminal.
Non-enzymic glycation of individual plasma proteins in normoglycemic and hyperglycemic patients.
Authors: Austin G E , Mullins R H , Morin L G 
Published: January 2020

Abstract
Diabetic patients in poor glycemic control show increased glycation of total plasma proteins, but little is yet known about the relative extents to which the various individual proteins are glycated. Thus, we studied the non-enzymic glycation of several major plasma proteins and plasma protein fractions in normal and diabetic patients. In vivo glycation for most plasma proteins was very low in non-diabetic patients, only gamma globulin showing more than 5% glycation. In diabetic plasmas, glycation was much greater, immunoglobulins again showing the greatest proportion, followed in descending order by albumin, complement C3, fibrinogen, transferrin, haptoglobin, and alpha-1-antitrypsin. When plasma proteins were glycated in vitro, this order was IgG greater than complement C3 greater than albumin greater than transferrin greater than haptoglobin greater than alpha-1-antitrypsin. In general, proteins with the longest biological half-lives, such as IgG and albumin, showed the greatest in vivo glycation. On the other hand, proteins with high intrinsic glycability, such as complement C3, showed moderate glycation, despite a short half-life. Except for albumin, more basic proteins showed greater glycation than acidic proteins, but there was poor correlation between mole percent lysine and glycation. Evidently the relative extents of glycation of different plasma proteins are a complex function of integrated glucose concentrations over time and of the half-life and chemical characteristics of each protein.
Determination of cyclosporine concentrations with monoclonal antibodies.
Authors: Schran H F , Rosano T G , Hassell A E , Pell M A 
Published: January 2020

Abstract
We measured cyclosporine in whole blood from normal volunteers administered single oral doses of the drug and from two renal-transplant patients on immunosuppressive maintenance therapy, by liquid chromatography (I) and by radioimmunoassay with use of nonspecific polyclonal (II), specific monoclonal (III), and nonspecific monoclonal (IV) antibodies. Concentrations determined by III were equivalent to I, irrespective of cyclosporine dose, concentration, time after dose, or time after transplant. Concentrations determined by II and IV were consistently higher than those by I, owing to cross reactivity with metabolites. Ratios of values by II and IV to those by I increased from less than 1.5 to about 3-4 between 0.5 and 12 h after a single cyclosporine dose, owing to differences in rates of appearance and disappearance of cyclosporine and cross-reacting metabolites, though for the constant 12-h dose intervals in the two renal-transplant patients at steady state these ratios (most within the range 3-4) were relatively stable. Ratios of concentrations measured by IV to those by II (mean of 1.2 for single-dose data, most within the range of 1.2 to 1.5 at steady state) were unaffected by time after dose or time after transplant, suggesting that, despite certain cross-reactivity differences between the two nonspecific antibodies, results are proportional throughout therapy. We therefore propose that III and IV offer alternatives, respectively, to the currently used I and II for cyclosporine monitoring.
A monoclonal antibody-based enzyme-linked immunosorbent assay of alpha 1-acid glycoprotein.
Authors: Fraeyman N H , Van de Velde E J , De Smet F H 
Published: January 2020

Abstract
A "sandwich"-type enzyme-linked immunosorbent assay for determining concentrations of human alpha 1-acid glycoprotein (AGP) is described. Microtiter plates coated with a polyclonal rabbit antibody to human AGP were subsequently incubated with the antigen, with a specific murine monoclonal antibody, and with goat anti-mouse immunoglobulins conjugated to alkaline phosphatase. To evaluate the method for assay of AGP in human sera, we compared it with single radial immunodiffusion and "rocket" electroimmunoassay. The respective correlations were r = 0.988 (n = 45) and r = 0.973 (n = 47). Repeated assays of a human serum sample with an average AGP concentration of 859 mg/L yielded within-day and between-day CVs of 1.4% (n = 5) and 6.3% (n = 10), respectively. Because of its low detection limit (4.4 micrograms/L), this assay is also suitable for determination of AGP concentrations in other biological fluids, such as dialysates of patients being treated by continuous ambulatory peritoneal dialysis.
Lipoperoxides in plasma as measured by liquid-chromatographic separation of malondialdehyde-thiobarbituric acid adduct.
Authors: Wong S H , Knight J A , Hopfer S M , Zaharia O , Leach C N , Sunderman F W 
Published: January 2020

Abstract
This assay of plasma lipoperoxides involves hydrolysis in dilute H3PO4 at 100 degrees C; complexation of malondialdehyde (MDA), a hydrolysis product, with thiobarbituric acid (TBA); methanol precipitation of plasma proteins; fractionation of the protein-free extract on a C18 column; and spectrophotometric quantification of the MDA-TBA adduct at 532 nm. The detection limit was 0.15 mumol of MDA per liter of plasma. Run-to-run precision (CV) averaged 8 to 13%. Analytical recovery of MDA after addition of tetraethoxypropane standards to 21 specimens of human or rat plasma averaged 98% (SD 7%). Lipoperoxide concentrations (as MDA) averaged 0.60 (SD 0.13) mumol/L in plasma specimens from 41 healthy persons and 1.4 (SD 0.3) mumol/L in plasma specimens from 12 control rats. Mean lipoperoxide concentrations were 1.5 to 2.3 times as great in plasma sampled from rats one to three days after subcutaneous administration of NiCl2 at dosages (250 to 750 mumol per kilogram body wt) previously shown to induce lipid peroxidation in lung, liver, and kidney.
Determination of inorganic fluoride in blood with a fluoride ion-selective electrode.
Authors: Kissa E 
Published: January 2020

Abstract
Inorganic fluoride in whole blood, serum, or plasma has been determined with a fluoride ion-selective electrode by adding the 0.5- to 2.0-mL sample to 20 mL of water containing a buffer and fluoride, 25 micrograms/L. The fluoride concentration in the sample is calculated from the resulting cell potential difference recorded after equilibrating for 10 min. This novel method has the advantages of simplicity, accuracy, and high precision, standard deviations for 5 to 7 replicate determinations of fluoride ranging from +/- 1.7 to +/- 2.4 micrograms/L. For whole blood from donors living in an area with fluorinated drinking water, the F- concentration was 20 to 60 micrograms/L.
Dilution of plasma with Tris buffer increases measured catecholamines in plasma.
Authors: Cuche J L , Selz F , Ruget G , Gentil M , Gaudin C 
Published: January 2020

Abstract
We investigated the effects of dilution of plasma samples on the measured concentrations of catecholamines. Diluting samples of human plasma 10-, 50-, and 100-fold with Tris buffer (100 mol/L, pH 8.6) improved analytical recovery of internal standards, suggesting that it decreases the commonly observed inhibition of methylation in radioenzymatic assays of catecholamines in plasma. However, the dilution is not associated with a proportional decrease in counted radioactivity. This extra amount of radioactivity, which is unlikely to be nonspecific in origin, accounts for a significant increase in the calculated catecholamine concentration. Tentatively, we suggest that Tris buffer releases both catecholamines and conjugated catecholamines bound to some unidentified low-molecular-mass component of plasma.