bluuebunny/crossref_metadata_2025_split huggingface dataset:
Basement membrane-related and type III procollagen-related antigens in serum of patients with chronic viral liver disease
Authors: Misaki M , Shima T , Yano Y , Sumita Y , Kano U , Murata T , Watanabe S , Suzuki S 
Published: January 2020

Abstract
To assess the significance of serum basement membrane- and type III procollagen-related antigens in reflecting the degree of liver fibrosis, we measured radioimmunologically the concentrations of 7S collagen, laminin fragment P1, and the aminoterminal propeptide of type III procollagen (P-III-P) in serum from 48 patients with chronic viral liver disease: chronic persistent hepatitis (9), chronic active hepatitis (13), chronic active hepatitis with lobular disorganization (17), and liver cirrhosis (9). Concentrations of 7S collagen, laminin P1, and P-III-P in serum were increased in respectively 92%, 69%, and 77% of the patients with both chronic active hepatitis with lobular disorganization and liver cirrhosis. Concentrations of 7S collagen and laminin P1 in serum correlated well (r = 0.65, P less than 0.001, and r = 0.55, P less than 0.001, respectively) with the histological grade of liver fibrosis, whereas P-III-P correlated only weakly (r = 0.33, P less than 0.05). Evidently, measurement of serum 7S collagen is a reliable noninvasive test for detection of fibrosis in chronic viral liver disease.
Radioimmunological determination of total thyroxin by antibodies immobilized on polystyrene tubes coated with styrene-maleic anhydride copolymers
Authors: Causse J E , Ricordel I , Bachelier M N , Kaddouche F , Nom B , Weil R , Descomps B , Yver J P 
Published: January 2020

Abstract
In this new technique for preparing activated polystyrene tubes for assay of human thyroxin (T4) we coated plastic with styrene-maleic anhydride copolymers. The quantity of antibodies immobilized on these tubes was considerably greater than on non-activated polystyrene tubes, and the time required for immobilization was shortened. Calibration curves were plotted, and determination of total T4 in 200 serum samples confirmed the expected increase in sensitivity as compared with a commercial (Gammacoat) method. The manufacturing procedure is simple and could easily be automated. Thus, such copolymer-coated tubes constitute an advantageous and reliable component in the assay of total T4 that can be used to improve the sensitivity of this and various other radioimmunological determinations.
Improved sample preparation in determination of urinary metanephrines by liquid chromatography with electrochemical detection
Authors: Gupta R N 
Published: January 2020

Abstract
In this relatively simple procedure for extracting metanephrines from urine, after an internal standard (4-hydroxy-3-methoxybenzylamine in 1 mmol/L HCl) is added, the sample is hydrolyzed in a boiling water bath, then treated with ammonia and alumina. Excess ammonia is removed under reduced pressure and the sample is applied to a 1-mL Bond Elut SCX column, which is washed, and metanephrines and internal standard are eluted with 0.5 mmol/L sodium acetate/acetonitrile (3/1 by vol). Of this elute, 5 microL is injected into a 15 cm x 4.6 mm (i.d.) column packed with 5-microns octadecylsilyl silica particles, which is eluted with a mobile phase containing tetramethylammonium perchlorate. Peaks are detected coulometrically at +0.28 V. In the resulting chromatogram, metanephrines give sharp peaks, well resolved from peaks for solvent and internal standard. There are no extraneous peaks for catechols or mono-oxygenated phenylethylamines. Results correlated well (r = 0.999, n = 13) with those by earlier described liquid-chromatography.
Automated determination of human choriogonadotropin by use of microparticle capture analysis
Authors: Trundle D S , Chou P P , Raymond A 
Published: January 2020

Abstract
We evaluated a new microparticle enzyme immunoassay (MEIA) for human choriogonadotropin (hCG) in serum. This hCG assay is fully automated for the Abbott "IMx System," which has a dynamic range extending to 100,000 int. units/L. We tested 321 patients' sera, with hCG values ranging between 0 and 196,000 int. units/L by both the IMx hCG (y) and the Hybritech Tandem-E hCG (x) assays. Results correlated well (r = 0.972, slope = 0.87, y-intercept = 0.7). The IMx hCG assay is sensitive (0.21 int. units/L) and precise (CVs 2.4-8.7% for various hCG concentrations). No carryover to subsequent specimens was observed when specimens with values up to 10(6) int. units/L were tested, nor was any high-dose "hook" effect noted. The IMx hCG assay, which is specific for intact hCG molecules, is rapid (one to six samples in 17 min) and is a valid automated alternative to enzymatic and radioisotopic methodologies.
3-Methylhistidine determined in plasma by "high-performance" lipid chromatography
Authors: van Eijk H M , Deutz N E , Wagenmakers A J , Soeters P B 
Published: January 2020

Abstract
In this fully automated method for determination of 3-methylhistidine (3MH) in plasma we use precolumn derivatization with o-phthaldialdehyde and subsequent separation by HPLC. Total analysis time is 36 min, and peak areas measured vary linearly with the amount of analyte injected, over the range of 0 to 20 pmol of 3MH (R2 = 0.995), with a coefficient of variation (CV) of 1.6%. The method is reliable, accurate, inexpensive, and at least 1000-fold more sensitive than conventional ion-exchange chromatography with ninhydrin. Because of its sensitivity, the method can be used to estimate venous-arterial differences. In four human volunteers the plasma 3MH concentration varied between 4.97 and 6.08 mumol/L, and the difference between "arterialized" and femoral venous blood for 3MH varied between 0.09 and 0.47 mumol/L.
Immunological assays of apolipoproteins in plasma: methods and instrumentation
Authors: Labeur C , Shepherd J , Rosseneu M 
Published: January 2020

Abstract
A number of immunological techniques--radioimmunoassay, enzyme-linked immunosorbent assay (ELISA), electroimmunoassay, radial immunodiffusion, and a variety of immunoprecipitin assays--have been used to quantify apolipoproteins in plasma. This paper outlines their technical details and discusses their major advantages and drawbacks. The most sensitive procedures, RIAs and ELISAS, are best suited to quantifying those apoproteins found in low concentration in plasma. Immunoturbidimetric assays, on the other hand, which are readily automated, are being widely used to quantify apolipoproteins A-I and B. Apolipoprotein quantification is complicated by the interaction of the proteins with lipids, which can often mask their antigenic determinants. This problem may be circumvented by pretreatment of the samples, by selection of appropriate standards, or by the use of polyclonal or monoclonal antibodies that interact with permanently exposed epitopes on the lipoproteins' surfaces. Our proposed methods for measurement of the individual apolipoproteins give consideration to these approaches.
In vitro and in vivo effects of increased concentrations of free fatty acids on free thyroxin measurements as determined by five assays
Authors: Sapin R , Schlienger J L , Grunenberger F , Gasser F , Chambron J 
Published: January 2020

Abstract
To compare in vitro and in vivo effects of increased concentrations of free fatty acids (FFA) on free thyroxin (FT4) values, we measured FT4 in three pooled sera supplemented with oleate and in serum from 18 euthyroid patients before and after an infusion of fat emulsion (Intralipid). We used five FT4 RIA kits: two two-step methods [Gammacoat, Baxter (GC); Ria-gnost, Behring (RG)], two analog RIAs [Amerlex-M, Amersham (AM); Coat-Ria, BioMérieux (CR)], and one kit with labeled antibodies [Amerlex-MAB*, Amersham (AA)]. In vitro, at the maximum oleate addition of 5 mmol/L, FT4 increased when measured by the GC and RG kits, decreased by the AM kit, and showed no significant change by the CR and AA kits. In vivo, post-Intralipid, FFA concentrations rose significantly and the FT4 changes agreed with the results of the in vitro experiments, except for the RG kit, for which FT4 increased in only nine patients. We conclude that in vitro oleate addition is useful to predict the in vivo effect of increased FFA on FT4 values; moreover, in serum from euthyroid subjects with high concentrations of FFA, FT4 analyzed with the CR or AA kits should better agree with normal results for thyrotropin than FT4 values measured with the other kits.
Thyrotoxic atrial fibrillation: an underdiagnosed or overdiagnosed condition?
Authors: Fagerberg B , Lindstedt G , Strömblad S O , Darpö B , Nyström E , Sjöström L , Lundberg P A , Olsson S B 
Published: January 2020

Abstract
Hyperthyroidism has been considered to be underdiagnosed as a pathogenetic factor for atrial fibrillation, according to results of thyroliberin stimulation tests. We assessed, clinically and biochemically, thyroid function in 110 ambulatory patients with atrial fibrillation [mean age 64 (SD 11) years] from a group of consecutive cases referred to a specialist cardiology unit during one year. Patients finally categorized as euthyroid (n = 100) commonly presented with one or more symptoms or signs considered to be typical for thyrotoxic patients. Three patients (2.7%; 95% confidence interval, 0-7.5%) fulfilled criteria for hyperthyroidism, but only one was identified from clinical examination. The thyroliberin stimulation test (performed in all patients) identified another seven patients who might have been classified as hyperthyroid according to commonly used criteria for an abnormal thyrotropin response. However, none of these seven patients was judged as hyperthyroid after follow-up. Their thyrotropin concentrations were all above the detection limit for the immunoenzymometric assay. With few exceptions, they had thyroid hormone concentrations within reference limits calculated from the results for the 100 euthyroid subjects, and their concentration ratio for free 3,5,3'-triiodothyronine to free thyroxin, 0.31 (SD 0.05), was lower than that found in the euthyroid group [0.38 (SD 0.08), P less than 0.05]. We conclude that (a) criteria for evaluating results of the thyroliberin stimulation test should be revised, (b) this test is still useful in evaluating suspected cases of hyperthyroidism, for which results of current, improved methods for thyrotropin determination are equivocal, and (c) improved diagnostic methods should be used to characterize the relative importance of hyperthyroidism as a causal factor for atrial fibrillation.
Serum carbonic anhydrase III and myoglobin concentrations in acute myocardial infarction
Authors: Väänänen H K , Syrjälä H , Rahkila P , Vuori J , Melamies L M , Myllylä V , Takala T E 
Published: January 2020

Abstract
Serum concentrations of myoglobin (S-Myo) and carbonic anhydrase III (S-CA III; EC 4.2.1.1), a skeletal muscle-specific protein, were measured by RIA in 26 patients with acute myocardial infarction, 14 patients with neuromuscular diseases, and six healthy subjects before and after physical exercise. S-Myo was increased in infarct patients, whereas S-CA III was not altered. In patients with neuromuscular diseases and in healthy subjects after physical exercise, both S-Myo and S-CA III were significantly increased. S-CA III and S-Myo also showed identical peak times, 2 h postexercise. The S-Myo/S-CA III ratio was always higher in infarct patients than in the other groups. Thus, the combination of S-CA III and S-Myo determinations is useful to differentiate whether serum myoglobin is originating from myocardium or from skeletal muscle.
Concentrations of free thyroxin and albumin in serum in severe nonthyroidal illness: assay artefacts and physiological influences
Authors: Midgley J E , Sheehan C P , Christofides N D , Fry J E , Browning D , Mardell R 
Published: January 2020

Abstract
Free thyroxin (FT4) estimates by two immunoassays were compared with the concentrations of albumin in serum of apparently euthyroid subjects who either were (n = 99) or were not (n = 327) suffering from severe nonthyroidal illness (sNTI). In neither group was FT4 significantly correlated with albumin (P greater than 0.05), according to a "labeled antibody" radioassay (Amerlex-MAB). On amalgamating both groups, correlation with albumin was positive and significant (P less than 0.001). In the group with sNTI, both FT4 and albumin concentrations were decreased (mean FT4 to 77% and mean albumin to 61% of the respective reference means). For an analog radioimmunoassay (Amerlex-M), FT4 in all groups was significantly (P less than 0.001) correlated with albumin. Correlation coefficients were greater than with Amerlex-MAB for both sNTI and euthyroid groups, as well as for the joint panel. Mean FT4 in sNTI was only 44% of the reference mean. Lower radio-tracer "analog" values in sNTI are exaggerated by additional technical artefacts resulting from tracer binding to albumin.
heterogeneity of creatine kinase isoenzyme MM in serum in myocardial infarction: interconversion of the "normal" and "abnormal" sub-bands by glutathione
Authors: Williams J , Williams K M , Marshall T 
Published: January 2020

Abstract
We used isoelectric focusing (IEF) in polyacrylamide gels to investigate the effects of glutathione on the sub-bands of serum creatine kinase (CK; EC 2.7.3.2) isoenzyme MM in acute myocardial infarction. The intensity of the "abnormal" sub-bands c (pI 7.25), e (pI 6.85), and g (pI 6.50) increased, and that of the "normal" sub-bands 1 (pI 6.91), 2 (pI 6.65), and 3 (pI 6.35) decreased, following serum incubation with reduced glutathione (GSH, final concentration 1.25 mmol/L). Further incubation with oxidized glutathione (GSSG, final concentration 5 mmol/L) reversed this change and restored the original pattern, whereas GSSG at 7.5 mmol/L caused sub-bands c, e, and g to disappear and sub-bands 1, 2, and 3 to be enhanced. Sequential incubation of serum with 2.5 mmol of GSSG and 7.5 mmol of GSH per liter produced the opposite sequence of events; i.e., the "abnormal" sub-bands disappeared then reappeared (and GSH at 10 mmol/L enhanced their reappearance). At higher concentrations, glutathione (GSH or GSSG) impaired the detection of the CK-MM sub-bands after IEF, an effect that was "quenched" by heat-inactivated serum of low CK activity. Likewise, the intensity of tissue CK-MM (corresponding to myocardium extracted into 100 mmol/L Tris HCl buffer, pH 7.4) was greatly enhanced by adding heat-inactivated serum to the tissue extract before IEF. We discuss the significance of these findings for the diagnosis of myocardial infarction.
Decreased storage stability of creatine kinase in a cardiac reperfusion solution
Authors: Dunphy G , Ely D 
Published: January 2020

Abstract
Creatine kinase (CK; EC 2.7.3.2) has been used as an indicator of myocardial cellular damage. In this study we used a Krebs-Henseleit (KH) solution to reperfuse isolated rat hearts after 24 h of cold preservation and collected the KH reperfusate for assay of CK to assess cellular damage. We wanted to determine the stability of CK in the KH solution at different cold-storage temperatures and albumin concentrations. CK activity (mean +/- SEM) after one week of refrigeration (5 degrees C) was 93% +/- 1% of control values, whereas CK activity in nitrogen-frozen (-200 degrees C) samples was only 1.6% +/- 1% of control values, and that in samples frozen at moderately low temperatures (-10 degrees C) was 63% +/- 1% of control values. To enhance stability, we added albumin at several concentrations (49, 25, 12, and 6 g/L) to reperfusion collections in which CK had been previously determined. Specimens were frozen (-10 degrees C), then re-analyzed for CK weekly for three weeks. CK activity was maintained (100% +/- 5%) only in samples containing 25 g/L or more albumin. These data suggest that refrigeration (5 degrees C) for one week maintains normal CK activity in KH solution; however, if prolonged storage is necessary, a stabilizer such as albumin (greater than or equal to 25 g/L) will maintain analyte stability in frozen storage (-10 degrees C) for at least three weeks.
Sensitive and rapid colorimetric immunoenzymometric assay of ferritin in biological samples
Authors: Ramm G A , Duplock L R , Powell L W , Halliday J W 
Published: January 2020

Abstract
We describe a rapid and sensitive enzyme-linked immunosorbent assay (ELISA) for quantifying ferritin in human and rat biological fluids. We used chlorophenol red beta-D-galactopyranoside as the colorimetric substrate of beta-galactosidase (EC 3.2.1.23), which is coupled to specific antibodies to either human or rat liver ferritin. The assay is sensitive (detection limit for human assay = 0.58 micrograms/L and for rat assay = 0.37 micrograms/L), accurate (average recovery for human assay = 93% and for rat assay = 92%), and precise (total CVs for human assay = 2.3-12.2% and for rat assay = 5.6-11.3%). The results correlated well with those of an established immunoradiometric technique (r = 0.99691). This assay has a prolonged shelf-life, is inexpensive, and utilizes a stable colorimetric substrate that requires relatively short incubation.
Heterophilic antibodies in human sera causing falsely increased results in the CA 125 immunofluorometric assay
Authors: Boerman O C , Segers M F , Poels L G , Kenemans P , Thomas C M 
Published: January 2020

Abstract
An in-house OC 125 monoclonal antibody-based "sandwich" immunofluorometric assay (IFMA) described previously (Clin Chem 1987; 33:2191-4) gave higher results for CA 125 in 37 of 123 serum samples than did a commercially available immunoradiometric assay (IRMA). Discordant results between the two assays became concordant when measurements of the samples were repeated with normal mouse serum (100 mL/L) included in the IFMA reagent. The murine immunoglobulins are thought to block the ability of the heterophilic antibodies in the human serum samples to cross-link the labeled antibody with the solid-phase antibody. Using an enzyme immunoassay, we demonstrated human anti-mouse antibodies (HAMA) in most of the discordant samples examined. We tested the ability of nonimmune sera from other animal species to lower the apparent CA 125 concentrations of the spurious samples and observed that rat, goat, and sheep serum were less effective than mouse serum. One serum sample was discovered to give a falsely increased CA 125 result with the IRMA, but this increase could be prevented by adding murine serum to the IRMA reagent. We conclude that falsely increased CA 125 results are best prevented by adding murine serum (or murine antibodies) to the assay buffer.
Light has a greater effect on direct bilirubin measured by the bilirubin oxidase method than by the diazo method
Authors: Ihara H , Aoki Y , Aoki T , Yoshida M 
Published: January 2020

Abstract
We compared the effect of light on direct-reacting bilirubin (DBIL) measurement by the bilirubin oxidase (EC 1.3.3.5; BOX) method and by the Jendrassik-Gróf diazo method. DBIL concentrations determined by the BOX method in the sera of hyperbilirubinemic infants treated with phototherapy yielded falsely higher values than those by the direct diazo method. A similar tendency was noted when DBIL concentrations in infants' sera irradiated with light in vitro were determined by both methods, although by HPLC none of these sera had detectable DBIL (i.e., conjugated plus delta bilirubin). In general, DBIL concentrations after photoirradiation remained unchanged when measured by the diazo method, but significantly increased when the BOX method was used. Indeed, photoirradiation gave rise to material that acted like a photobilirubin product, which was oxidized at pH 3.7 and therefore was measured as DBIL. Such false increases in DBIL values generated by the BOX method may have clinical diagnostic implications in monitoring jaundiced neonates and in differentiating between physiological jaundice and incipient pathological jaundice.
Differential assay of zidovudine and its glucuronide metabolite in serum and urine with a radioimmunoassay kit
Authors: Tadepalli S M , Puckett L , Jeal S , Kanics L , Quinn R P 
Published: January 2020

Abstract
We developed an ancillary procedure for the ZDV-Trac RIA (Incstar) to allow simultaneous determination of both zidovudine (3'-azido-3'-deoxythymidine, ZDV, AZT, Retrovir) and its metabolite, the glucuronide of ZDV (3'-azido-3'-deoxy-5'-O-beta-D-glucopyranuronosylthymidine, ZDVG, GAZT), in human serum and urine. Using the ZDV-Trac RIA, we measured ZDV concentrations before and after ZDVG in samples was hydrolyzed to ZDV by beta-glucuronidase (EC 3.2.1.31); ZDVG concentration was calculated as the difference between the two results. This method enables rapid evaluation of a large number of samples with a total turn-around time of 6 h. The lower detection limit of the RIA was 0.27 micrograms/L; the measurements varied linearly with ZDV concentrations from 0.27 to 217 micrograms/L, with the 50% inhibitory concentration being approximately 10 micrograms/L. Analytical recoveries of inhouse serum and urine controls for both ZDV and ZDVG exceeded 90%. Coefficients of variation (CVs) of serum controls were less than 6% for ZDV and less than 11% for ZDVG; for urine controls, CVs for both ZDV and ZDVG were less than 6%. Results for ZDVG concentrations obtained by HPLC and by the ZDV-Trac RIA system compared well: r = 0.978, slope 1.0, for serum samples, and r = 0.993, slope 1.09, for urine samples.
Simultaneous determination of disopyramide and mono-N-dealkyldisopyramide enantiomers in plasma and urine by use of a chiral cellulose-derivative column
Authors: Echizen H , Ochiai K , Kato Y , Chiba K , Ishizaki T 
Published: January 2020

Abstract
This assay allows simultaneous determination of the enantiomers of both disopyramide and its active metabolite, mono-N-dealkyldisopyramide, in 1 mL of plasma or 0.1 mL of urine within approximately 35 min by HPLC with a chiral cellulose-derivative column and ultraviolet detection. Recoveries for the analytes and the internal standard (racemic verapamil) with an extraction from alkalinized plasma or urine into diethyl ether were greater than 90%. Intra- and interassay CVs for disopyramide enantiomers were less than 5.5% at 2.5 mg/L in plasma and less than 6.5% at 25 mg/L in urine; for mono-N-dealkyldisopyramide enantiomers they were less than 6.3% and less than 8.9%, respectively. Intra- and interassay relative errors for determining these analytes in plasma and urine at 2.5 and 25 mg/L, respectively, ranged from -5.9% to +2.5%. The calibration curves for the respective analytes were linear (r = 0.995 or greater, P less than 0.01) from 0.025 to 5.0 mg/L in plasma and from 0.5 to 10 mg/L in urine. The lower detection limits (signal-to-noise ratio of 3) for S(+)-disopyramide and the other analytes were 0.010 and 0.025 mg/L, respectively. We evaluated clinical applicability of this method by determining steady-state plasma concentrations and urinary excretions of the respective analytes in a pediatric patient being treated with racemic disopyramide.
Ultrasensitive Time-Resolved Fluorescence Method for α-Fetoprotein
Authors: Christopoulos Theodore K , Lianidou Evrikiia S , Diamandis Eleftherios P 
Published: January 2020

Abstract
We have examined the maximum sensitivity of a newly developed and optimized time-resolved fluorescence immunoassay system. The system, originally described elsewhere Clin Biochem 1988;21:139-50), has undergone significant improvements in sensitivity through improvements of the labeled reagent used. We have chosen an α-fetoprotein [Illegible Text] assay as a model and used monoclonal "capture" antibodies and monoclonal or polyclonal biotinylated antibodies in "sandwich-type" assay configurations. Streptavidin labeled with the europium chelator 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid was used for detection. We can measure as few as 3 x 105 molecules of [Illegible Text] with the optimized system. We have applied this assay to measure AFP in the serum of normal individuals after a 10-fold sample dilution. We conclude that this system is extremely sensitive and can be used in immunoassay or other applications where biotinylated reagents can be applied.