bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitation of lactate by a kinetic method with an extended range of linearity and low dependence on experimental variables.
Authors: Hamilton S D , Pardue H L 
Published: January 2020

Abstract
We report conditions and characteristics of a new kinetic method for measuring lactate. Using a multiple linear regression method, we fit data for absorbance and for rate of change of absorbance to a modified rate form of the Michaelis-Menten equation. The principal objective of the fitting process is to compute the total absorbance change, delta A infinity, that would be measured if the reaction were monitored from the point of mixing to equilibrium. For data collected at 1-s intervals from 5 to 200 s, the fitting process gives values of delta A infinity that vary linearly with lactate concentration from 10.6 to 180 mumol/L in the reaction cell after 150-fold dilution of samples. For a range of enzyme activities that produced a 20% change in the initial rate, the regression-kinetic treatment yielded results with no detectable systematic error. The mean within-day CV was 2.1% for an average concentration of 14.4 mmol/L; the day-to-day CV was 5.2% for 3.90 mmol/L. For 25 samples of canine plasma with lactate concentrations from 2 to 26 mmol/L, comparison of results obtained with the regression-kinetic method (y) with results obtained with a commercially available equilibrium method (x) gave a least-squares equation of y = 1.01x - 10 mumol/L.
Immunonephelometry of apolipoprotein A-II in plasma.
Authors: Rosseneu M , Vinaimont N , Musliner T A , Bernier D , Herbert P N , Belpaire F 
Published: January 2020

Abstract
A quantitative assay based on endpoint immunonephelometry was developed for human apolipoprotein A-II (apoA-II) in plasma or serum. Dilution of plasma samples with a 0.1 mol/L solution of sodium cholate enhanced the quantification. We used either purified apoA-II as the primary standard or plasma as a secondary standard. Results correlated well (r = 0.90) with those by a double-antibody radioimmunoassay for 63 serum samples from both normal and hyperlipemic individuals. The interassay coefficient of variation for the immunonephelometric assay was 7% within a working range between 0.05 and 0.7 microgram of apoA-II per sample (corresponding to a 1500-fold final dilution of serum). No extraction of samples with organic solvent is necessary if the triglyceride concentration is less than 4 g/L.
Determination of inorganic sulfate in plasma with a centrifugal analyzer.
Authors: Pascoe P J , Peake M J , Walmsley R N 
Published: January 2020

Abstract
Turbidimetry of inorganic sulfate, after precipitation with barium sulfate, can be done simply in a Cobas Bio centrifugal analyzer. Polyethylene glycol is used as the precipitate-stabilizing agent. Reproducibility of precipitation is enhanced by the presence of BaSO4 particles, which function as seed nuclei. There is no interference by normal or above-normal concentrations of phosphate, heparin, bilirubin, hemoglobin, or erythrocyte contents, or by lipemia (triglyceride concentrations up to 6.5 mmol/L). Analytical recovery of added inorganic sulfate was found to be quantitative. Precision is similar to that for other methods for inorganic sulfate in plasma. This method is suitable for the rapid, routine analysis of plasma inorganic sulfate, and it is simple and less expensive to perform than alternative methods.
Effect of contrast media on radioimmunoassay of beta-endorphin in cerebrospinal fluid.
Authors: Fang V S , Fessler R G , Rachlin J R , Brown F D 
Published: January 2020

Abstract
An effect of metrizamide, a contrast medium, on results of beta-endorphin radioimmunoassay was examined. We found that 1, 5, and 10 microL of the medium added to 100 microL of standard containing 0 to 500 pg of beta-endorphin shifted the standard curve to the left in proportion to the metrizamide concentration. Three other contrast media showed a similar effect at low concentrations of beta-endorphin. This effect of contrast media artificially increased results in radioimmunoassay of beta-endorphin in cerebrospinal fluid, the mean overestimate being 121.9% (range, 0 to 435%). For plasma samples, this effect of contrast media resulted in an average 11.7% overestimate of beta-endorphin (range, -16% to 41%). These observations bring into question the validity of a previous suggestion that an increase in beta-endorphin in cerebrospinal fluid after intracerebral electrical stimulation is the mechanism for stimulation-produced analgesia.
Sources of error in determinations of carnitine and acylcarnitine in plasma.
Authors: Fishlock R C , Bieber L L , Snoswell A M 
Published: January 2020

Abstract
Radioactive and nonradioactive L-carnitine and acyl-L-carnitine were used to evaluate the washing procedures used during the determination of free, total, short-chain, and long-chain acylcarnitine in human and sheep plasma. The volume of fluid trapped by the protein precipitated by perchloric acid is approximately 24% of the total fluid volume and thus contains 24% of free carnitine and short-chain acylcarnitine. Washing twice with distilled water removes about 25% of the long-chain acylcarnitine along with the trapped free carnitine and short-chain acylcarnitines. Washing the pellet twice with a 60 g/L solution of perchloric acid completely removes the trapped free carnitine and short-chain acylcarnitine but does not remove the bound long-chain acylcarnitines. Thus washing with perchloric acid is essential for accurate measurement of long-chain acylcarnitines in plasma samples.
Differentiating two forms of plasma lipase by use of media with different ionic strengths.
Authors: Arzoglou P L , Férard G , Métais P 
Published: January 2020

Abstract
Three different techniques of lipase (EC 3.1.1.3) determination (titrimetry, nephelometry, and enzyme immunoassay) were used to investigate an interesting effect of ionic strength on enzyme activity. Both activation in the presence of NaCl (140 mmol/L) and strong immunoinhibition were observed for lipase from plasma of subjects with acute pancreatitis. Another type of lipase, not associated with pancreatitis and only weakly immunoinhibited, showed maximum activity in the presence of 80 mmol/L NaCl. The pancreatitis-type lipase was activated by 140 mmol/L NaCl solution only if colipase and sodium deoxycholate were also present, which suggests that these components are cofactors in the activating effect and confirms the specificity of this property. These findings can be exploited to improve the diagnosis of acute pancreatitis.
Changes in sodium and uric acid concentrations in plasma during the menstrual cycle.
Authors: Mira M , Stewart P M , Gebski V , Llewellyn-Jones D , Abraham S F 
Published: January 2020

Abstract
Hormonal changes during the menstrual cycle are well documented, but many other biochemical variables have not been studied. We find that in the luteal phase of the menstrual cycle the concentrations of sodium and uric acid are significantly lower. The changes may be of significance for the determination of the normal reference interval.
Progress report on a national quality-control survey of triiodothyronine and thyroxin assay.
Authors: Zucchelli G C , Pilo A , Chiesa M R , Piro M A 
Published: January 2020

Abstract
In January 1980, a national external quality-control survey was organized to evaluate assays for triiodothyronine (T3) and thyroxin (T4). Currently, about 150 laboratories are involved. Each participant has received and assayed 100 quality-control samples during four periods of about six months each. The average analytical performance achieved by the participants in each six-month period was estimated by computing the average between-laboratory agreement (CVT), the overall average bias, and the average laboratory imprecision. During the 2.5 years of the survey, analytical performance has improved for both assays (CVT decreased from 17.0 to 15.7% for T3 and from 13.1 to 12.7% for T4). Analysis of survey results according to the method/kit used (mean kit bias and kit imprecision for the nine kits most used by participants) showed that the analytical reliability of the T4 assay is generally better than that observed for T3, mainly because of the larger systematic differences among T3 kits.
An international comparison of vitamin D metabolite measurements.
Authors: Jongen M J , Van Ginkel F C , van der Vijgh W J , Kuiper S , Netelenbos J C , Lips P 
Published: January 2020

Abstract
An international 19-laboratory survey was organized to compare assays for 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D in plasma. Each participant received two ethanolic standard solutions of each metabolite and eight plasma samples. Each laboratory used its usual procedures. Mean interlaboratory coefficients of variation (CVs) for the eight plasma samples were 35%, 43%, and 52% for 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D, respectively. Average CVs for the standard solutions were 27%, 23%, and 25%, respectively. Of the eight plasma samples, five had the same concentration for one of the metabolites. One sample was diluted to 0.6 times its original concentration and three samples were fortified with one or more of the metabolites under investigation. Fourteen of 18 laboratories (78%) could distinguish between the five unchanged samples and the modified ones with their 25-hydroxyvitamin D assay. Nine of 12 (75%) could distinguish the modified samples from the other samples with the 24,25-dihydroxyvitamin D assay. Only eight of 15 (53%) could do this their 1,25-dihydroxyvitamin D assay. Values from different laboratories evidently cannot be intercompared without making an actual comparison of the assay procedures. Furthermore, in case of clinical applications of these assays, each laboratory should establish its own reference values and should continually use an internal reference sample to assess the precision of the procedures.
Profile of creatine kinase isoenzymes in skeletal muscles of marathon runners.
Authors: Apple F S , Rogers M A , Sherman W M , Costill D L , Hagerman F C , Ivy J L 
Published: January 2020

Abstract
The proportion of creatine kinase (CK; EC 2.7.3.2) isoenzyme MB activity was increased in skeletal muscle biopsies obtained from five long-distance runners, both 2 h before (mean 7.7%, SD 2.4%) and 30 min after (mean 7.2%, SD 1.2%) a marathon race, as compared with that in biopsies from five nonrunners (controls less than or equal to 1.0%). Further, mitochondrial CK and CK-BB isoenzymes were present in homogenates of the runners' skeletal muscle samples but not in those of the nonrunners. However, there were no substantial differences in the mean total CK activities per gram (wet wt.) of muscle tissue among premarathon samples, postmarathon samples, and nonrunners' samples (3148, 3365, and 3049 U/g, respectively). We conclude that the metabolically active gastrocnemius muscle of long-distance runners is qualitatively similar to the heart muscle in its CK isoenzyme composition.
Early detection of myocardial infarction by an immunoradiometric procedure for creatine kinase MB.
Authors: Dods R F 
Published: January 2020

Abstract
I investigated the diagnostic efficacy of the Embria-CK immunoradiometric assay (IRMA) in detecting myocardial infarction, using a single blood sample drawn at hospital admission 0 to 10 h after the onset of chest pain and serial testing over a 24- to 48-h interval after hospital admission. The sensitivity, specificity, and efficiency for hospital admission samples were 87.5, 83.3, and 85.0%, respectively, and for serial testing, 100, 79.2, and 87.5%, respectively. The diagnostic efficacy was comparable to that of electrophoresis and significantly better than the Du Pont CK-MB method.
Direct analysis for urinary protein with biuret reagent, with use of urine ultrafiltrate blanking: comparison with a manual biuret method involving trichloroacetic acid precipitation.
Authors: Eckfeldt J H , Kershaw M J , Dahl I I 
Published: January 2020

Abstract
We describe a method for measuring urinary protein with a centrifugal analyzer. Biuret reagent is used, and blanking with an ultrafiltrate of urine eliminates interferences from the nonprotein, biuret-positive chromogens in urine. We compare results by this new method with those by a manual method in which trichloroacetic acid precipitation and biuret reagent are used. The new method shows good precision and excellent correlation (r = 0.997) with the manual method. The ease and convenience of this assay should make this a useful method for the routine clinical laboratory.
Neutral carrier electrode for continuous measurement of blood Ca2+ in the extracorporeal circulation.
Authors: Anker P , Ammann D , Meier P C , Simon W 
Published: January 2020

Abstract
A neutral-carrier-based Ca2+-selective electrode exposed to whole blood exhibited an EMF-stability better than 0.13 mV (approximately 1% change of the initial activity) during 3.7 to 6.6 h. It has been used successfully to monitor ionic Ca2+ in the extracorporeal circulation during administration of calcitonin to dogs. Data simulation shows that the apparent concentration of ionic Ca2+ is affected by the concentration of Na+. A variation in [Na+] by +/- 5 mmol/L from a value of 143 mmol/L used for the calibration leads to uncertainties of +/- 0.8% in the Ca2+ concentration and +/- 0.2% in the Ca2+ activity if 3 mol/L KCl is used as the reference electrode solution. When an isotonic solution was used as reference electrolyte, errors of +/- 0.8% and +/- 1.7%, respectively, were observed.
A densitometer based on a microcomputer and TV camera, for use in the clinical laboratory.
Authors: Tracy R P , Young D S 
Published: January 2020

Abstract
We describe a microcomputer-based densitometer that includes a television camera for the analysis of one- and two-dimensional electrophoresis gels. The hardware configuration is a modification of that described by Mariash et al. (Anal Biochem 212: 388-394, 1982). The video signal is digitized by a commercially available interface, yielding 1 of 64 greyscale values for each pixel examined. The operator controls the region being analyzed through the use of a joystick and video monitor. We have optimized the linear response range (0-1.5 A) and have written a relatively simple control program ("GELSCAN 5.0"). For analyses of one-dimensional gels, the required operator decisions include the start and finish points of the gel, the width of the scan (analogous to slit size), and the level of background correction. The digital information may be stored on disk, displayed by one of several graphic routines, and analyzed for total scan and individual peak absorbance values. Similar analyses may be done with two-dimensional gel spots.
Effect of use of gel-barrier sampling tubes on determination of some antiepileptic drugs in serum.
Authors: Bergqvist Y , Eckerbom S , Funding L 
Published: January 2020

Abstract
We evaluated the effect on drug concentration of the duration of sample storage in three different tubes for blood collection: SST (Becton Dickinson), AutoSep (Terumo), and Microvette (Sarstedt), all of which contain an inert barrier (e.g., gel) for cleaner separation of serum from coagulum during centrifugation. With two of the tubes (SST and AutoSep) we examined samples taken from patients undergoing treatment with phenobarbital, phenytoin, and carbamazepine. We found significant decrease in the drug, concentration after 24 h with the serum standing over the gel barrier in the SST tubes for phenobarbital and both the SST and AutoSep tubes for carbamazepine. Adding aqueous drug solutions or serum samples supplemented with the above drugs in therapeutic concentrations to the three types of tubes resulted in a more pronounced decrease of concentration in the SST and Auto-Sep tubes than in the Microvette tubes.
Acetaldehyde-hemoglobin adducts: an unreliable marker of alcohol abuse.
Authors: Homaidan F R , Kricka L J , Clark P M , Jones S R , Whitehead T P 
Published: January 2020

Abstract
Acetaldehyde reacts with hemoglobin in vitro to produce acetaldehyde-hemoglobin adducts, but we could not detect these in the blood of 20 alcoholics, either by cation-exchange chromatography or agar gel electrophoresis. Thus, contrary to previous reports, this test is not a reliable marker of alcohol abuse. Nuclear magnetic resonance and gas chromatographic-mass spectroscopic analysis of acetaldehyde revealed the presence of aldehydic impurities. Formation of adducts in vitro may thus result from the reaction of hemoglobin with these impurities or with acetaldehyde condensation products (aldol) or from acetaldehyde condensation/dehydration products (crotonaldehyde).
Enzymic colorimetric determination of phosphatidylglycerol in amniotic fluid.
Authors: Artiss J D , McGowan M W , Strandbergh D R , Epstein E , Zak B 
Published: January 2020

Abstract
We describe a procedure for the enzymic, colorimetric determination of phosphatidylglycerol in amniotic fluid. After extraction into chloroform:methanol (2:1 by vol) and evaporation, the phospholipid-containing residue is redissolved in a non-ionic detergent, which thus provides an aqueous sample. The subsequent enzymic reaction sequence involves phospholipase-catalyzed hydrolysis of glycerol from its phospholipid. Subsequent enzyme-catalyzed reactions phosphorylate this glycerol and oxidize the resulting glycerol phosphate to produce hydrogen peroxide, which is reacted to produce an intense red chromogen in the peroxidase-catalyzed coupling of 4-aminoantipyrine and 2-hydroxy-3,5-dichlorobenzenesulfonate. When used in conjunction with previously reported enzymic techniques for determination of lecithin and sphingomyelin, this procedure may provide an accurate and precise "lung profile" for assessment of fetal lung maturity.
Iodination of thyroliberin by use of Iodogen.
Authors: Butler S R , Lam R W , Fisher D A 
Published: January 2020

Abstract
In this method of labeling thyroliberin for radioimmunoassay, 1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril (Iodogen) is used as oxidant. By cation-exchange chromatography and in response to antibody, thyroliberin so labeled behaved similarly to that produced by the conventional Chloramine-T method. Major advantages of the Iodogen method are its reliability, simplicity, and higher yield of stable RIA label in its most convenient (diiodinated) form.
Effects of storage temperature and time before centrifugation on ionized calcium in blood collected in plain vacutainer tubes and silicone-separator (SST) tubes.
Authors: Toffaletti J , Blosser N , Kirvan K 
Published: January 2020

Abstract
We studied the stability of ionized calcium and pH in samples stored at either room temperature or 4 degrees C, in centrifuged and uncentrifuged blood-collection tubes and in centrifuged tubes containing a silicone-separator gel (SST tubes). At room temperature, in uncentrifuged blood from healthy individuals, mean ionized calcium usually increased no more than 10 mumol/L per hour; at 4 degrees C it did not change detectably for 70 h. This stability was fortuitous, however: the concentrations of both hydrogen and lactate ions in these samples increased, apparently with offsetting effects on the concentration of ionized calcium. Blood stored for 70 h at 4 degrees C in centrifuged SST tubes, although showing a slightly greater change in ionized calcium, had less change of pH and no change in the ionized calcium corrected to pH 7.4. In 11 heparinized whole-blood samples from eight patients in intensive care, the mean change per hour in ionized calcium and pH after storage at room temperature was +10 mumol/L and -0.04 units, respectively.
Interrelationships among body mass, thyrotropin, thyroid hormones, and thyroid-hormone binding proteins in healthy 70-year-old men.
Authors: Edén S , Jagenburg R , Lindstedt G , Lundberg P A , Mellström D 
Published: January 2020

Abstract
In a previous study of a representative population of 460 men of age 70, we found that the free thyroxin (free T4) concentration was negatively correlated to body mass. In the present study we analyzed other indicators of thyroid function in relation to body mass and body mass index in 181 individuals without any disease or medication influencing thyroidal homeostasis or body mass. There was a significant negative relationship between body mass and body mass index and free T4, total T4, and 3,3',5'-triiodothyronine (rT3). Thus, individuals with high body mass normally had lower circulating concentrations of these hormones than lean individuals, whereas there was no such relationship for thyrotropin or 3,5,3'-triiodothyronine (T3). The thyroid-hormone binding proteins (thyroxin-binding globulin, prealbumin, and albumin) did not correlate with body mass or body mass index. As expected, thyroxin-binding globulin correlated with T4, T3, and rT3, but not with free T4 or thyrotropin. Concentrations of serum albumin correlated with T3 and rT3 concentrations but not with free T4, T4, or thyrotropin concentrations. Thyrotropin concentrations correlated negatively with free T4, T4, and rT3, but not with T3, indicating that circulating T4 plays the dominant role in feedback regulation of thyrotropin in healthy individuals.
Transferability studies for the AACC reference method and the IFCC method for measurement of alkaline phosphatase activity.
Authors: Tietz N W , Rinker A D , Burtis C , Duncan P , Ervin K , Ewen L , Hørder M , Mathieu M , Petitclerc C , Grisley D 
Published: January 2020

Abstract
We present the results of measurements of alkaline phosphatase activity from interlaboratory transferability studies conducted by 12 laboratories in five countries. The variability, as demonstrated by within-day precision (CV less than or equal to 2.6%), between-day precision (CV less than or equal to 3.6%), and between-lab precision (CV less than or equal to 6.3%) establishes the transferability of this method for alkaline phosphatase. Some common errors encountered in enzyme measurements that affect the accuracy and precision of the measurements are listed.
Removal of a component interfering with phosphatidylglycerol estimation in the "Helena" system for amniotic fluid phospholipids.
Authors: Spillman T , Cotton D B , Lynn S C , Bretaudiere J P 
Published: January 2020

Abstract
A simple " prechromatography " step removes a component of amniotic fluid ("pseudo PG") that otherwise co-chromatographs with phosphatidylglycerol in the system for amniotic fluid analysis developed by Touchstone et al. (Lipids 15: 61-62, 1980) and incorporated into the Helena "Fetal-Tek" kit. The final positions of the major phospholipids are practically unchanged but the faster migrating, more neutral components are swept into a tight band near the solvent front, providing improved general resolution. The resulting change in the ratio of "phosphatidylglycerol" to sphingomyelin ("PG"/S) is as much as 0.5 for some specimens, but no change is seen for others. In 20% of the 73 cases examined, including four of the six fluids associated with respiratory distress syndrome, the PG initially reported was found to be "pseudo PG" and was completely removed by the prechromatography step. This step produces a negligible decrease in the lecithin to sphingomyelin (L/S) ratio in amniotic fluid.
Screening for macroamylase in a community hospital.
Authors: Isham C A , Ridgeway N A , Hedrick R , Cate J C 
Published: January 2020

Abstract
We evaluated the polyethylene glycol precipitation test (Gastroenterology 83: 378-382, 1982), looking for macroamylase in the serum of 66 patients whose values for serum amylase were above normal. Three patients (4.5%) were identified by this method as having macroamylase , and this was confirmed by gel-filtration chromatography and electrophoresis. We find this to be the test of choice as a screening procedure for macroamylasemia because of its speed, simplicity, and apparent reliability. Diagnosis of macroamylasemia is important in preventing needless treatment and investigation for pancreatitis.