bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of plasma triglyceride concentrations on the accuracy of immunoturbidimetric assays of apolipoprotein B
Authors: Walmsley T A , Grant S , George P M 
Published: January 2020

Abstract
We have studied the influence of triglyceride-rich particles on the analytical bias of apolipoprotein B measurements by various immunoturbidimetric methods. Three commercially available methods grossly overestimate apolipoprotein B in samples with even moderately above-normal triglyceride concentrations. This effect is due to the increased relative reactivity of very-low-density lipoproteins in these reagent systems, and can be eliminated by including Tween 20 (2 g/L) in the reagent buffer. We have developed, and describe, an automated immunoturbidimetric method that allows the accurate determination of apolipoprotein B in the plasma of patients with hypertriglyceridemia.
The role of the laboratory in evaluation of kidney function
Authors: Cohen Eric P , Lemann Jacob 
Published: January 2020

Abstract
Evaluation of kidney function by physical examination alone is imprecise and limited. Quantitative, reproducible assessment of kidney function required laboratory measurements of substances in plasma and urine, followed by reliable interpretation. Thus, glomerular filtration, urine protein excretion, water metabolism, and electrolyte disturbances may be quantified. These data are very useful in the single and serial assessment of patients with kidney disease and in evaluation of the effects of treatment.
Rapid monitoring of benzodiazepines in clinical samples by using on-line column switching HPLC
Authors: Moore C M , Sato K , Katsumata Y 
Published: January 2020

Abstract
We have determined routinely administered benzodiazepines and some of their metabolites in clinical samples by using on-line column switching for sample clean-up and reversed-phase high-pressure liquid chromatography (HPLC). The plasma sample is directly injected onto a cyanopropyl (CN) pre-column, washed with buffer, and eluted onto an analytical column (C18, octadecylsilane). Analytical recovery from drug-supplemented plasma samples was greater than 85% for all the benzodiazepines tested. The response of the analytical column varied linearly with drug concentrations over the range 0.01-1 mg/L in plasma, with CVs ranging from 0.3% to 1.8% within-day and 5.5% to 15.7% between days. The detection limit (signal-to-noise ratio greater than 3) was 0.01 mg/L (1 ng on column) for all of the benzodiazepines and their metabolites. The advantages of the technique include the extreme cleanliness of the traces, no requirement for off-line sample preparation, and ease of automation.
Measurement of prostate-specific antigen and prostatic acid phosphatase concentrations in serum before and 1-42 days after transurethral resection of the prostate and orchidectomy
Authors: Price Alun , Attwood Stephen E A , Grant jhon B F , Gray Trevour A , Moore Kenneth T H 
Published: January 2020

Abstract
Preoperative intra-individual variation for determinations of prostate-specific antigen and prostatic acid phosphatase concentrations, 15-30% in 92 patients with benign prostatic hyperplasia, limits the diagnostic usefulness of both tumor markers. In benign prostatic hyperplasia (214 patients), concentrations of these tumor markers increased in the initial postoperative period. Prostatic acid phosphatase concentration then decreased by the third postoperative day. Prostate-specific antigen concentration remained above normal in the first postoperative week but had decreased by 42 days. In prostatic carcinoma (46 patients), the concentrations of these tumor markers did not increase postoperatively. During the first week, the concentrations of prostatic acid phosphatase began to fall, but prostate-specific antigen showed a decrease only at 42 days. After orchidectomy (11 patients), the concentrations of both markers had decreased by five days. Concentrations of prostate-specific antigen but not of prostatic acid phosphatase were significantly increased in patients with metastases at 42 days postoperatively. When the concentration of tumor marker did decrease, the magnitude of change was greater for prostatic acid phosphatase than for prostate-specific antigen. These changes were accentuated after an orchidectomy.
Enzymatic fluorometric procedure for phospholipid quantification with an automated microtiter plate fluorometer
Authors: Nanjee M Nazeem , Gebre Abraham K , Miller Norman E 
Published: January 2020

Abstract
We describe a new enzymatic assay for phospholipids that is rapid, sensitive, convenient, and inexpensive. The method is based on the fluorometric detection of H2O2, generated by the choline oxidase-catalyzed oxidation of choline, after liberation of choline from phospholipids by phospholipase D. Significant advantages over existing methods are that the entire reaction sequence can take place in a single vessel, a 12 x 8 well microtiter plate, and that the fluorescence intensity can be measured automatically with a Fluoroskan II (Labsystems Oy) detector. Extracting samples with organic solvents is unnecessary, although the method can be applied to extracts in isopropanol. The assay is approximately 60-fold more sensitive and has a limit of detection eightfold lower than currently available enzymatic colorimetric methods. Including solvent blanks, eight standards, and three quality-control pools, 34 samples can be pipetted and assayed in duplicate in 60 min. Results obtained by this procedure for total phospholipid choline in lipoproteins in primate plasma agreed well with those obtained for inorganic phosphorus by the Bartlett acid-digestion procedure.
Simple method for preparing a concentration gradient of serum components by freezing and thawing
Authors: Hirano Tetsuo , Yoneyama Toshiaki , Matsuzaki Hiroko , Sekine Takainitsu 
Published: January 2020

Abstract
We created a simple method for obtaining a series of successively more-concentrated samples from a serum without changing the ratio of its components. We froze a pooled serum and then allowed it to thaw undisturbed. The serum components formed a gradient of increasing concentration from the top of the sample to the bottom. We found that (a) in test results, each fraction of serum in the gradient showed almost the same relative concentrations of components (i.e., inorganic and organic compounds, proteins, metals, and hormones), irrespective of atomic or molecular mass; (b) the concentration gradient depended on the thawing temperature but not on the freezing temperature; (c) when we thawed the frozen sample with centrifugation, the slope of the concentration gradient increased with increasing centrifugal force; (d) when the thawed sample was fractionated into 10 fractions from the top to the bottom, the original serum concentration was always maintained between the sixth and seventh fractions from the top; and (e) the concentration gradient became steeper with repeated freezing and thawing. By using this method, one can easily prepare serum samples at gradients of concentration useful in the clinical laboratory, although the mechanism of gradient formation is still unclear.
Changes in oxygen measurements when whole blood is stored in iced plastic or glass syringes
Authors: Mahoney John J , Harvey James A , Wong Ronald J , Van Kessel Antonius L 
Published: January 2020

Abstract
Tonometered whole-blood and plasma specimens were tested in plastic and glass syringes to determine whether clinically significant changes in gas tensions occur during sample storage. When whole blood was tonometered with 60 and 100 mL/L (6% and 10%) oxygen and then stored for 30 min in iced plastic syringes, the pO2 of the samples remained stable (mean change = +0.4 and +0.8 mmHg, respectively). However, for 140 mL/L (14%) oxygen tonometry, the pO2 increased significantly (mean change = +8.4 mmHg; P less than 0.0001). When tonometered plasma was stored in iced plastic syringes, the pO2 increased progressively at all three concentrations, with the smallest change occurring at 140 mL/L (mean change = +12.6 mmHg) and the greatest at 60 mL/L oxygen (mean change = +20.9 mmHg). In contrast, when iced glass syringes were used for storing plasma or whole blood, no clinically significant changes in pO2 were found at any of the tonometered oxygen values for 60 min. When whole blood was stored in plastic syringes at ambient temperature for 30 min, again no clinically significant changes in pO2 were found at these tonometry conditions. Apparently, some blood gas samples stored in iced plastic syringes may yield clinically significant errors in oxygen tension.
Effects of serum-isolated vs synthetic bilirubin-albumin complexes on dye-binding methods for estimating serum albumin
Authors: Ihara H , Nakamura H , Aoki Y , Aoki T , Yoshida M 
Published: January 2020

Abstract
Bush and Reed reported (Clin Chem 1987;33:821-3) that the reaction of albumin with bromcresol purple but not with bromcresol green underestimated the concentration of albumin in synthetically obtained bilirubin-albumin (Bd) by 29%. Their unproven assumption was that chemically synthesized Bd behaved in a manner indistinguishable from the natural Bd in icteric serum. Here we verify that Bd, whether synthetically obtained or isolated from serum, causes an underestimation of albumin in the bromcresol purple but not in the bromcresol green method. The molar ratio of Bd from either source to underestimated albumin approximates 1.0, suggesting that one molecule of Bd would react equivalently to a molecule of albumin in the bromcresol purple method. This underestimation might falsely suggest hypoalbuminemia in patients with increased serum Bd.
Isopropylidine maltoheptosyl fructofuranoside, doubly blocked substrate for determination of endoamylase activity
Authors: Ogawa Z , Matsubayashi Y , Satoh S , Orita N , Itoh H 
Published: January 2020

Abstract
We synthesized o-(4,6-o-isopropylidene-alpha-D-glucopyranosyl)-(1----4)- [o-alpha-D-glucopyranosyl-(1----4])5-o-alpha-D-glucopyranosyl-(1----2)- alpha-D-fructofuranoside (IPG7F) and developed an assay for determining the activity of amylase in human serum and urine by using this substrate. Glucoamylase, alpha-glucosidase, and mannitol dehydrogenase are used as coupling enzymes. The coupled reactions are monitored by continuously measuring the oxidation rate of NADH. In this procedure, various substances in the test specimens do not interfere with the detection of amylase activity. Exactly one molecule of NADH is oxidized by one attack of amylase on the substrate, although four products can be produced in the reaction. The within-assay coefficient of variation (CV) ranged from 1.0% to 4.1% and the between-assay CV ranged from 2.6% to 5.3%. The results of our new assay correlate well with those of the amylase assay involving p-nitrophenol maltoheptaoside as substrate (r = 0.978) and with those of the amylase assay involving maltopentaose (r = 0.987).
Development and application of monoclonal antibodies to human cardiac myoglobin in a rapid fluorescence immunoassay
Authors: Silva D P , Landt Y , Porter S E , Ladenson J H 
Published: January 2020

Abstract
Myoglobin (Mb) is considered a useful marker for early detection of myocardial infarction and for monitoring cardiac reperfusion after thrombolytic therapy. We developed eight monoclonal antibodies to human cardiac Mb, characterized their epitopic reactivity, and determined which combinations of the antibodies are useful in two-site immunoassays. We configured two of the monoclonal antibodies in a one-step, two-site particle concentration fluorescence immunoassay (PCFIA) for measurement of Mb. The PCFIA has rapid kinetics of reaction, being complete in 15 min, and has a linear analytical range of 20-675 micrograms/L for human Mb. Although the PCFIA has a high-dose "hook" effect, this is of no analytical importance at concentrations of Mb less than or equal to 148,000 micrograms/L. The assay is not subject to interference from icterus (bilirubin less than or equal to 360 mg/L), has no cross-reaction with hemoglobin (less than or equal to 42 g/L), and may be performed with either plasma or serum in approximately 1 h. The intra- and interassay imprecisions (CV) of the method are less than 10% for concentrations of Mb within the normal range and less than 4% at higher concentrations. A comparison of the PCFIA with a commercial radioimmunoassay showed that results of the two assays correlate well (PCFIA = 0.88 x RIA + 18, r = 0.990, n = 171).
Influence of intermediate-density lipoproteins on the accuracy of the Friedewald formula
Authors: Sentí M , Pedro-Botet J , Nogués X , Rubiés-Prat J 
Published: January 2020

Abstract
Values of low-density lipoprotein (LDL) cholesterol (C) according to the Friedewald formula (Clin Chem 1972;18:499-502) were compared with those obtained by lipoprotein fractionation in 98 healthy subjects (control group), 135 specimens from patients with peripheral vascular and cerebrovascular disease (atherosclerotic group), and 45 with chronic renal failure on hemodialysis (CRF group). All had concentrations of total cholesterol between 3.23 and 7.76 mmol/L (1.25-3.00 g/L) and triglycerides less than 3.39 mmol/L (less than 3.00 g/L). The percentage error of calculated LDL-C was 4% in controls with a cholesterol/triglycerides (C/TG) ratio for very-low-density lipoprotein (VLDL) of 0.20, but greater than 60% in those with a (C/TG)VLDL ratio of 0.40. The percentage of error in sera of patients with atherosclerosis and chronic renal failure was higher than in controls with a similar mean (C/TG)VLDL ratio. The percentage of error of calculated LDL-C increases progressively with the increase in the C/TG intermediate-density lipoprotein (IDL) ratio, both in controls and in the atherosclerotic and CRF groups. Similar findings are observed when the mean percentage of error of measured LDL-C is evaluated. The percentage of error from calculated LDL-C in the atherosclerotic and CRF groups is significantly lower than that obtained by comparison of LDL-C separated by ultracentrifugation when the "broad cut" LDL (IDL plus LDL, both by ultracentrifugation) was used. The high percentage of errors found in the groups of patients studied underlines the need for caution when assessing the reliability of the Friedewald formula, particularly in cases in which disturbances in IDL composition are suspected.
Simple, sensitive measurement of carbon monoxide in plasma
Authors: Chalmers A H 
Published: January 2020

Abstract
A simple, sensitive method for estimating carbon monoxide in plasma is described. In this method, the carbon monoxide in plasma is trapped with hemoglobin and subsequently estimated by dithionite reduction. The method has an intra- and interassay precision (CV) of 10.7% and 12.8%, respectively, at a concentration of 1.12 mg of carbon monoxide per liter and has a detection limit of 0.1 mg/L. The reference interval for carbon monoxide in plasma from 17 men and eight women ranged from 0.14 to 0.60 mg/L (mean 0.36 mg/L).
2,3-Butanediol in plasma from an alcoholic mistakenly identified as ethylene glycol by gas-chromatographic analysis
Authors: Jones A W , Nilsson L , Gladh S A , Karlsson K , Beck-Friis J 
Published: January 2020

Abstract
2,3-Butanediol was mistakenly identified as ethylene glycol in plasma specimens from two alcoholic patients. The cyclic phenylboronate ester derivatives of 2,3-butanediol and ethylene glycol had the same retention time when OV-17 was used as the stationary phase for gas chromatography. This led to incorrect diagnosis of ethylene glycol poisoning and unnecessary invasive therapy. Plasma from two chronic alcoholics contained 2,3-butanediol at 3.5 and 3.4 mmol/L. The elimination half-life of 2,3-butanediol was 3.9 days when ethanol was administered during therapy for suspected ethylene glycol poisoning. Low concentrations of 2,3-butanediol might be present in blood of chronic alcoholics as a result of a novel pathway of intermediary metabolism associated with some forms of alcoholism. However, a more likely explanation for fairly high concentrations of 2,3-butanediol is enzymatic production from 2-butanone. This ketone occurs in denatured alcohol preparations often consumed by alcoholics in Sweden.
Time-resolved fluorescence detection of enzyme-amplified lanthanide luminescence for nucleic acid hybridization assays
Authors: Templeton E F , Wong H E , Evangelista R A , Granger T , Pollak A 
Published: January 2020

Abstract
A new nonisotopic detection method based on time-resolved fluorescence for nucleic acid hybridization assays with alkaline phosphatase labels has been developed: enzyme-amplified lanthanide luminescence (EALL). EALL combines the amplification of an enzyme label with the sensitivity and background elimination of time-resolved fluorescence detection of lanthanide ion luminescence. The detection system for alkaline phosphatase makes use of a phosphorylated salicylic acid derivative that, upon dephosphorylation, gives a product capable of forming a luminescent terbium chelate. We demonstrate DNA hybridization assays by using two substrates, one for membrane and one for solution-based formats. Using the substrate that produces a more adhesive product allows performance of dot-blot and Southern blot assays on nylon membranes; results can be recorded with a time-resolved photographic camera system, or with an ultraviolet transilluminator-based system. Less than 4 pg of target sequence can be detected in a dot-blot assay after incubation with substrate for 2-4 h. DNA microwell-plate hybridization assays with the more soluble substrate/product pair can be quantified with time-resolved fluorescence plate readers, giving a similar detection sensitivity. EALL is thus a practical time-resolved fluorescence-based alternative to other detection systems for DNA hybridization assays.
The integrated blood-collection system as a vehicle into complete clinical laboratory automation
Authors: Columbus R L , Palmer H J 
Published: January 2020

Abstract
A rationale is offered and methodology illustrated for integrating the fundamental steps involved in the collection and processing of blood for laboratory evaluation. The approach taken in the development of these concepts and components greatly extends the possibilities of laboratory systems integration without upsetting established modalities. A prototype design of the integrated blood-collection system integrates blood collection, cellular separations, sample transfer to stable storage without chemical mediators, and sample presentation for chemical analysis (e.g., precision metering) while preserving patient identification. A sophisticated, multi-chambered blood-collection container is the site of all blood sample processing and transfer steps. This device is supported by a compact, robotic centrifuge of unique design and a transfer mechanism to facilitate sample delivery for analysis within a diagnostic instrument. The confluence of these individual components into a single integrated system provides the means to completely automate the processing of blood samples, after sample collection, eliminating all manual transfer steps and any external exposure of blood interfaces outside the diagnostic instrument. Configurational derivatives of the Integrated Blood-Collection System offer choice of skin or venipuncture procedure, rapid plasma extraction for micro- or macro-collected volumes, and sample delivery by either aspiration or direct metering of discrete 10-microL samples from the collection container. The skin-puncture configuration provides the opportunity within a single device to collect and process up to 500 microL of sample by capillarity from a skin prick.
Time course of changes in pancreatic enzymes, isoenzymes and, isoforms in serum after endoscopic retrograde cholangiopancreatography
Authors: Panteghini M , Pagani F , Alebardi O , Lancini G , Cestari R 
Published: January 2020

Abstract
Kinetics of the catalytic activities of total amylase (AMY; EC 3.2.1.1), pancreatic (P)-AMY isoenzyme, P2 and P3 isoforms, and pancreatic lipase (LPS; EC 3.1.1.3), and of the mass concentration of LPS in serum were studied in 10 patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) and showed a distinct pancreatic injury. The temporal characteristics of enzyme changes described were (a) the maximal rate (Ka) at which enzymes are released into blood, (b) the time lag from ERCP until maximum concentration value, (c) the peak value of each serum enzyme, and (d) the rate (Kd) at which each enzyme is cleared from serum. LPS activity and mass concentrations increased and decreased faster than AMY and isoamylases, and the time of the LPS peak tended to be earlier than that of the other enzymes, but not significantly. The average peak increase of LPS values was higher than that of total AMY, P-AMY, and P2 isoform (P less than 0.001). The P-AMY time-activity curve was a composite of curves attributable to its isoforms; the isoforms increased and peaked sequentially, with P3 returning to normal more slowly than did P2. LPS mass and activity concentrations showed excellent parallelism, with no important differences. At 50 h after ERCP, only LPS values still exceeded the upper reference limit, returning to normal 70 h after the examination.
One-Step, Labeled-Antibody Assay for Measuring Free Thyroxin. I. Assay Development and Validation
Authors: Christofides N D , Sheehan C P , Midgley J E M 
Published: January 2020

Abstract
We describe a one-step, labeled-antibody radioassay for measuring free thyroxin (FT4) in serum or plasma, based on a novel principle. FT4 in the sample competes with a gross molar excess (over antibody) of a cross-reactant (L-triiodothyronine, T3), chemically coupled to magnetizable polymer particles, for binding to avid 125l-labeled monoclonal anti-thyroxin antibodies. As in conventional immunoassays, 125I counts bound to the solid phase (T3-magnetizable particles) are inversely proportional to sample FT4 concentration. We demonstrate here the development and technical validity of this new method.
Methods for Measuring Plasma Hemoglobin in Micromolar Concentration Compared
Authors: Fairbanks Virgil F , Ziesmer Steven C , O'Brien Peter C 
Published: January 2020

Abstract
Of eight methods examined for measuring plasma hemoglobin in micromolar concentration, all exhibited acceptable linearity, reproducibility, and concurrence except when specimens were icteric or lipemic or contained methemoglobin or methemalbumin. Measurement of absorbance at 578 nm with an Allen correction permits precise assay of plasma oxyhemoglobin concentration as low as 0.01 g/L (1 mg/dL, 0.16 mumol/L), unaffected by hyperlipidemia or hyperbilirubinemia. Discrepancies between methods occurred in 11.6% of a consecutive series of 50 nonicteric patients' plasma specimens. Examination of absorption spectra is helpful when discrepancies are observed between methods. The presence of methemalbumin or methemoglobin in plasma is not recognized by methods that measure only oxyhemoglobin. Increased ceruloplasmin or beta-carotene does not significantly affect results.
Measurement of low-density-lipoprotein cholesterol in serum: a status report
Authors: Rifai Nader , Warnick G Russell , McNamara Judith R , Belcher John D , Grinstead Gregory F , Frantz Ivan D 
Published: January 2020

Abstract
Current recommendations of the Adult Treatment Panel and the Children and Adolescents Treatment Panel of the National Cholesterol Education Program make the concentration of low-density lipoproteins cholesterol (LDL-C) in serum the basis for the classification and treatment of hypercholesterolemia. Numerous methodologies for the determination of serum LDL-C concentrations, in research and clinical laboratories, have been described. Here, we review the principles, performance, and limitations of major current methodologies for determining LDL-C concentrations. These methods include sequential and density-gradient ultracentrifugation, chromatographic and electrophoretic techniques, and precipitation methods. In addition, the advantages and disadvantages of estimating LDL-C concentration by the Friedewald equation, the most commonly used approach in clinical laboratories, are addressed.