bluuebunny/crossref_metadata_2025_split huggingface dataset:
Convenient method for checking detector response of spectrophotometers at three wavelengths.
Authors: Frings C S , Muscat V I , Waldrop N T 
Published: January 2020

Abstract
We describe the use of a water-soluble dye, available as green food coloring, to check the linearity of detector response of spectrometers and spectrophotometers at three wavelengths. The dye has absorbance maxima at 257 nm, 410 nm, and 630 nm. The advantages of using this solution for this important instrument function check are: one solution with absorption maxima in the opposite ends of the visible spectrum as well as in the ultraviolet region; safe; inexpensive; readily available; easy to use; absorbance not dependent on pH from 2.5 to 10.0 or on temperature from 4 to 56 degrees C.
A computerized system for storage and statistical analysis of clinical amino acid data.
Authors: Schoengold D M , Miner D J , deFiore R H , Hamilton P B 
Published: January 2020

Abstract
We have developed a system of computer programs to expedite analyses of amino acid data obtained in a clinical environment. The system contains a program for building and maintaining libraries of chromatogram data, and a program for retrieval of data on the basis of any of its associated biographical characteristics. Several programs have been written that work with data drawn from the libraries. They provide for easy presentation, manipulation, or statistical analysis of the data. Included are comparison of population means and variances and intra-population correlation analyses. A minicomputer that has 12K of core storage is adequate for use with the system.
Effect of time and temperature on blood P50 and 2,3-diphosphoglycerate measurements.
Authors: Hellerstein S , Bunthrarungroj T 
Published: January 2020

Abstract
The oxygen affinity of hemoglobin is affected by various factors, including blood pH and erythrocyte 2,3-diphosphoglycerate. The latter and blood P50 values are unchanged when aliquots of blood from normal individuals are permitted to stand at room temperature for as long as 7 h. Our data also show that equilibration in a 37 degrees C tonometer for times ranging from 0.5 to 1.5 h causes no detectable alterations in P50 values.
Electrophoretic amylase fractionation as an aid in diagnosis of pancreatic disease.
Authors: Legaz M E , Kenny M A 
Published: January 2020

Abstract
Six alpha-amylase (EC 3.2.1.1) isoenzymes have been resolved electrophoretically on cellulose acetate membranes in a discontinuous buffer system. The fastest migrating isoenzymes are of salivary origin (S1, S2, S3), the slower ones of pancreatic origin (P1, P2, P3). We determined the amylase isoenzyme distribution in the sera of 240 subjects. A specific pancreatic isoenzyme (P3) was observed in all clinically diagnosed cases of acute or chronic pancreatitis as well as in 15 of 40 renal-transplant patients. Moreover, P3 isoenzyme activity declined during apparent recovery from pancreatitis. The P2 isoenzyme appeared in 95% of all specimens, P1 in only 2%. The pancreatic isoenzymes were preferentially excreted in the urine of both renal-transplant patients and normal individuals. The major salivary isoenzyme, S1, was observed in 95% of all serum and urine samples; however, the S2 and S3 appeared less consistently. Our method is simple and rapid, and quite applicable for use in clinical evaluation of patients with pancreatitis or with certain nonpancreatic dysfunctions.
Thermodynamic aspects of some radioassays.
Authors: Keane P M , Walker W H , Gauldie J , Abraham G E 
Published: January 2020

Abstract
In a number of radioimmunoassays and radiotransin assays, effective equilibrium constants have been measured at different temperatures in order to define the relative contribution of changes of entropy and enthalpy to the change in free binding energy. In systems with a large enthalpy component, the lowest possible incubation temperature maximizes sensitivity, and control of temperature throughout the assay is important. Conversely, when enthalpy change is small, a high temperature allows rapid attainment of equilibrium without loss of sensitivity. At a theoretical level, the thermodynamic characteristics of binding may allow some insight into the nature of the binding process.
Determination of phenprocoumon, an anticoagulant, in human plasma.
Authors: DeWolf F A , VanKempen G M 
Published: January 2020

Abstract
Phenprocoumon is extracted from acidified plasma, the organic phase evaporated, and part of the residue, in ethanol, is quantitatively applied to a thin-layer plate. After separation, the quantity of phenprocoumon is assayed by fluorescence densitometry in situ. Results are reproducible to about 2.5%. The lower limit of detection is 0.1 mg/liter, which makes the method fully applicable to human plasma, because therapeutic concentrations range from 1 to 3 mg/liter. Seven determinations can be made within 3 h. For toxicological purposes, a qualitative analysis can be done in a shorter time, because the phenprocoumon spots are visible under ultraviolet light at 254 nm.
Kinetic determination of hexosaminidases for Tay-Sachs heterozygote screening.
Authors: Zinterhofer L , Schuttringer G 
Published: January 2020

Abstract
We describe a method for continuous kinetic measurement of hexosaminidase activity, and have applied it to detection of heterozygotes for Tay-Sachs gene. In contrast to existing single-point methods, a ph of 4.5, which is optimal for hexosaminidase activity on the substrate (4-methylumbelliferyl-N-acetyl-beta-d-glucosaminide) is maintained while the increase in fluorescence produced by 4-methylumbelliferone, the reaction product, is being determined. Under the conditions described the reaction follows zero-order kinetics, and activity is linearly related to serum dilution. There is a fairly narrow but practicable range of optimal substrate concentration. The presence of substrate in concentrations exceeding 1 mmol/liter results in progressive quenching of fluorescence and a decrease in apparent enzyme activity. The procedure is standardized with 4-methylumbelliferone in a solution of the substrate. This method is adaptable to use with automated multiple-point discrete-sample devices and especially with the fluorometric kinetic analyzers now being developed.
Factors contributing to intra-individual variation of serum constituents: Physiological day-to-day variation in concentrations of 10 specific proteins in sera of healthy subjects.
Authors: Statland B E , Winkel P , Killingsworth L M 
Published: January 2020

Abstract
Using an automated immunoprecipitin method, we assayed human sera for 10 proteins: haptoglobin, orosomucoid, transferrin, alpha1 antitrypsin, alpha2-macroglobulin, IgG, IGa, IgM, complement C3, and complement C4. Blood from 14 healthy subjects (25-40y) was sampled on six separate days. From each venipuncture serum was divided into four eliquots; two were assayed on the day of venipuncture and two were frozen and kept until the end of the study, when all of the frozen samples were analyzed in one batch. With this experimental design, batch-to-batch analytical variation could be estimated, and we avoided confounding it with the biological variation. Data analysis was based on the analysis of variance technique. The average physiological intra-individual coefficient of variation ranged from 2.5% for transferrin to 11.1% for orosomucoid. THe interindividual variation ranged from 9.5% for transferrin to 70.5% for haptoglobin and the ratio between intra-individual variation and interindividual variation ranged from 0.66 for IgM to 0.26 for orosomucoid and transferrin.
Automated radioimmunoassay of choriomammotropin (human placental lactogen).
Authors: Castro A , Prieto I , Wunsch C , Ertingshausen G , Malkus H 
Published: January 2020

Abstract
We describe a totally automated procedure for radioimmunoassay of choriomammotropin, in which all phases of the assay are automated in a single system ("Centria"). This system permits the simultaneous incubation and separation of many samples in a nonequilibrium assay, and measurements are obtained in less than 30 min. Results for clinical samples by reference radioimmunossay methodology and with the Centria system compared uniformly well: y=0.91x - 0.87;r=0.94. The coefficient of variation for samples run in duplicate on the same day was 5.2%, 7.4% for samples run on different days. The specificity, sensitivity, simplicity, and speed of this system makes it a useful new tool for kinetic, nonequilibrium immunoassay.
Simple modifications of three routine in vitro tests of thyroid function.
Authors: Pain R W 
Published: January 2020

Abstract
Semi-automation of equipment and simple modifications of technique reduced the work load without loss of diagnostic accuracy for three commonly used in vitro tests of thyroid function (total thyroxine, thyrobinding index, and free thyroxine index). Major innovations were the use of serum standards for all tests and having each duplicate for tests performed by a different technician. Attention is drawn to the false-positive and false-negative errors that occur when the 95% euthyroid limits is the sole reference range used.
Modified determination of total and inorganic mercury in urine by cold vapor atomic absorption sectrometry.
Authors: Littlejohn D , Fell G S , Ottaway J M 
Published: January 2020

Abstract
In this procedure a single-beam spectrophotometer is used without background correction. By the method of Magos [Analyst (London) 96, 847 (1971)] mercury in undigested urine is complexed to L-cysteine in acid solution. At high pH and in the presence of stannous ions, mercury ions are reduced to elemental mercury. The mercury vapor is partitioned above the reagent solution in a specially designed chemical reduction apparatus similar in principle to that used by Kubasik et al. [Clin. Chem. 18, 1326 (1972)]. The vapor is then flushed by air through an "absorption" cell, where the absorption of the mercury line at 253.7 nm is measured. The value obtained for inorganic mercury subtracted from that for total mercury gives a value for organic mercury. CV's for the inorganic mercury procedure at 40 and 5 mug/liter concentrations were 3.1% and 7.5%, respectively. The detection limit is 0.82 mug/liter. The CV for the total-mercury procedure (20 mug/liter) was 2.6%. Mean analytical recoveries of organic and inorganic mercury were 96.5% and 101%, respectively. We investigated storage conditions for urine and compared results by the present technique with those by activation analysis. Our method is a convenient way to screen individuals who have been exposed to a mercury hazard.
Use of values for calcium and protein in serum, and of a derived index obtained from a probability population sample.
Authors: Kelly A , Munan L , PetitClerc C , Ho K P , Billon B 
Published: January 2020

Abstract
We measured serum protein and calcium concentrations in 2340 individuals between 10 and 96 years of age from 900 families chosen by probability methods to give a representative population. These values were used to calculate an index, based on a regression analysis of serum protein on calcium, which was then treated as a new variable. Age-sex specific reference values and frequency distributions are presented for this index as well as for protein and calcium calculated by both parametric and nonparametric methods.
Bile acid and detergent interaction with radioassays based on coated charcoal.
Authors: Andersen K J , Schjonsby H , Skagen K W , von der Lippe G 
Published: January 2020

Abstract
We tested the radioassays for cyclic AMP and human gastrin, both involving separation on coated charcoal, for interaction with bile acids and detergents, and found a concentration-dependent interaction of taurocholic and glycocholic acid as well as of the surfactant Triton X-100 and sodium laurylsulfate in both assays. The interaction was detectable from concentrations of 0.5 mmol of bile acid per liter or 625 mg of detergent per liter, giving rise to falsely decreased gastrin values and falsely increased or decreased values for cyclic AMP. The interactions demonstrated may be a general effect on all radioassays that are based on the use of coated charcoal in the separation of free from bound ligands.
Nature of the interaction between low-density lipoproteins and polyanions and metal ions, as exemplified by heparin and Ca2+.
Authors: Cham B E 
Published: January 2020

Abstract
I examined the effect of lipid concentration on the interaction of the very-low density and low-density lipoproteins in serum with heparin and calcium. A precipitate forms when partly delipidated serum is subjected to the polyanion-metal ion system. Although this precipitate is less turbid than the complexed lipoprotein-polyanion-metal ion in undelipidated serum, the two precipitates contain identical amounts of apolipoprotein. Totally delipidated serum produces only a slight precipitate with heparin and calcium, and this precipitate contains only a fraction of the appolipoproteins. Cholesterol and triglycerides are the major determinants of turbidity when serum is mixed with heparin and calcium, but have no effect on the precipitation of the protein moiety. Phospholipids contribute a small proportion of the turbidity in the lipoprotein-polyanion-metal ion interaction. Precipitation of the low-density lipoproteins by heparin and calcium depends on the protein moiety and on the chemical composition of the lipid moiety. Phospholipid is required, but cholesterol and triglyceride are not, for total precipitation of the complex.
Plasma high-density lipoprotein cholesterol concentrations determined after removal of other lipoproteins by heparin/manganese precipitation or by ultracentrifugation.
Authors: Bachorik P S , Wood P D , Albers J J , Steiner P , Dempsey M , Kuba K , Warnick R , Karlsson L 
Published: January 2020

Abstract
The widely used heparin/MnCl2 precipitation procedure for determination of plasma high-density lipoprotein cholesterol has been re-examined in light of recent reports that isolated preparations of the lipoprotein are only partly precipitated under the test conditions. In the present study, the procedure as applied to plasma tolerated rather wide variations in heparin and MnCl2 concentrations without significant effects on the assayed values in several plasma pools tested. The procedure was further tested on 129 individual samples by comparison with an ultracentrifugal method in which high-density lipoprotein-cholesterol is assumed to be represented by the cholesterol content of the plasma fraction of relative (to water) density greater than 1.063. Our results indicate that high-density lipoprotein is not precipitated under the test conditions when applied to unfractionated plasma.
Erythrocyte uroporphyrinogen I synthase activity in diagnosis of acute intermittent porphyria.
Authors: Peterson L R , Hamernyik P , Bird T D , Labbé R F 
Published: January 2020

Abstract
Measurement of the activity of uroporphyrinogen I synthase provides an excellent laboratory aid in the diagnosis of acute intermittent porphyria, particularly in those patients who are asymptomatic or in whom the disease is not biochemically manifested by porphyrin precursor excretion. We describe here a simplified fluorometric method for measuring the activity of this enzyme in whole blood. The assay is based upon a coupled-enzyme procedure in which added delta-aminolevulinic acid and the dehydratase that is present in erythrocytes are used to generate porphobilinogen as substrate for uroporphyrinogen synthase. After appropriate incubation the protein is removed we sensitivity, specificity, and precision of the assay compare well with previously described procedures. Activity in nonporphyric male subjects was 31 (SD, 6.0) nmol of porphyrin formed per milliliter of erythrocytes per hour at 37 degrees C. Application of the method for identifying gene carriers of acute intermittent porphyria is demonstrated in three generations of an affected family.
Application of a vidicon spectrometer for simultaneous multicomponent drug determinations.
Authors: McDowell A E , Harner R S , Pardue H L 
Published: January 2020

Abstract
A rapid scanning vidicon spectrometer has been evaluated for the simultaneous determination of drugs in mixtures, without a separation step. Spectral data in the ultraviolet region are collected on-line with a small computer at repetition rates of 100 scans per second. Absorbance data at several wavelengths are processed by matrix equations to resolve them into the concentration of each component in each mixture. Results are reported for two-component mixtures of procainamide and N-acetylprocainamide in serum, for two-component aqueous mixtures of butabarbital and seconbarbital, and for seven-component aqueous mixtures of phenobarbital, diphenylhydantoin, aminophylline, acetaminophen, salicylamide, phenylbutazone, and secobarbital. We conclude that the computer-inter-faced vidicon spectrometer is a viable tool for simultaneous multicomponent determinations.
An evaluation of the Beckman chloride/carbon dioxide analyzer.
Authors: Hicks J M , Aldrich F T , Iosefsohn M 
Published: January 2020

Abstract
We compared the Beckman Cl/CO2 Analyzer to the American Instrument Company chloride titrator for measurement of chloride in serum, sweat, and spinal fluid. We also compared it to the Natelson gasometer and a modified continuous-flow (AutoAnalyzer) technique for measurement of carbon dioxide in serum. Effects of bilirubin and hemoglobin on results for both the CO2, and Cl were negligible. The linearity, stability, and precision of the equipment was studied. We believe the Beckman Cl/CO2 Analyzer to be ideal for simultaneous measurement of chloride and carbon dioxide in a pediatric or emergency-determination setting.
A search for the best buffer to use in assaying human lactate dehydrogenase with the lactate-to-pyruvate reaction.
Authors: Buhl S N , Jackson K Y , Lubinski R , Vanderlinde R E 
Published: January 2020

Abstract
Highly purified human lactate dehydrogenases I and V were assayed in 17 different buffers, at a variety of reaction pH's. Diethanolamine and 2-amino-2-methyl-1,3-propanediol provided the best measurements of the enzyme, assayed lactate-to-pyruvate. However, the commercial preparation of 2-amino-2-methyl-1,3-propanediol contained insoluble matter and was relatively expensive. All of the four buffers nowmost commonly used were found to present difficulties. Glycine and pyrophosphate were inhibotory tolactate dehydrogenase activity with increasing buffer concentration. 2-Amino-2-methyl-1-propanol had three major disadvantages: it is chemically unstable during reagent preparation; activity is dependent on buffer concentration; and the pH optima for isoenzymes I and V are vastly different. The pKa of tris(hydroxymethyl)aminomethane is 8.0 at 30 degrees C, whereas to measure total activity the reaction pH should be greater than 8.5; thus tris(hydroxymethyl)aminomethane has limited buffering capacity at the reaction pH.
Aspartate aminotransferase activity in human serum. Factors to be considered in supplementation with pyridoxal 5'-phosphate in vitro.
Authors: Horder M , Moore R E , Bowers G N 
Published: January 2020

Abstract
The pyridoxal phosphate reactivation of the apo form of aspartate aminotransferase (EC 2.6.1.1) in human serum has been studied with "normal" and above-normal activity of this enzyme. The extent of the reactionation did not depend on the presence of the substrates, L-aspartate or 2-oxoglutarate. Reactivation was greatest with 110 mumol of added pyridoxal phsophate present per liter during a preinucation for 7 min in tris(hydroxymethyl)methylamine buffer wit;h serum volume fractions ranging from 0.017 to 0.267. In comparison with measurements prformed with no exogenous pyridoxal phosphate present, we found two potential sources of error when this cofactor was added: (a) reagent and sample blanks in the pyridoxal phosphate-supplemented system were two- to eightfold higher and (b) progress curves were nonlinear when L-aspartate rather than 2-oxoglutarate was used as the startin substrate. Aspartate aminotransferase measurement sith pyridoxal phosphate supplementation was slightly more precise than without.
Improved thyroxine radioimmunoassay, for filter paper discs saturated with dried blood.
Authors: Mitchell M L 
Published: January 2020

Abstract
I describe an improved procedure for estimating thyroxine in dried blood on 0.32-cm filter paper discs, by radioimmunoassay. A weak anion-exchange resin is used to separate free and antibody-bound radiothyroxine and, by measuring the resin-bound 125I-labeled thyroxine rather than the supernatant radioactivity, a tedious and cumbersome step is eliminated. The unique properties of the resin permit considerable latitude in the experimental conditions, in contrast with charcoal, without compromising sensitivity or precision. There is excellent correlation between thyroxine values obtained from discs and those of the corresponding plasmas. Application of this procedure for large-scale screening of newborns has proved to be highly successful in identifying thyroid insufficiency in several babies before clinical signs were apparent.
Negative anion gap in a young adult with multiple myeloma.
Authors: Gumprecht T , O'Connor D T , Rearden A , Wolf P L 
Published: January 2020

Abstract
A young patient with multiple myeloma was found to have a negative anion gap, with marked asymptomatic hyponatremia. The cause for his negative anion gap is thought to be the myeloma protein, which acts as a cation at physiological pH. Such a hyponatremia responds to reduction in serum concentration of paraprotein and should not be treated by sodium replacement.
Diazotization of catecholamines and their analogs and metabolites for urinary screening tests: chemical aspects.
Authors: Vauquelin G , Verheyden R , Ebinger G , Strosberg A D 
Published: January 2020

Abstract
Coupling of diazotized p-nitroaniline to catecholamines and their metabolites in urine has been proposed for use in screening for secreting neuroblastoma in childhood. We have coupled diazotized p-nitroaniline to catecholamines, derivatives, and metabolites and examined the reaction products by thin-layer chromatography and physico-chemical methods (ultraviolet spectra, mass spectroscopy, nuclear magnetic resonance). We conclude that during diazotization, products containing a p-hydroxybenzyl alcohol or a p-hydroxybenzoic acid structure (e.g., vanillic acid, vanilmandelic acid, 3-methoxy-4-hydroxyphenyl-ethyleneglycol, metanephrine, normetanephrine, synephrine, and isoproterenol) react with a diazonium cation, with release of their alcohol or acid moiety. Therefore the mentioned qualitative screening methods are very nonspecific. In contrast, thin-layer chromatographic screening methods provide complete separation and unambiguous identification of those metabolites and are to be preferred for use in detecting secreting neuroblastoma in childhood.
Microscale modification of a cation-exchange column procedure for plasma ammonia.
Authors: Oberholzer V G , Schwarz K B , Smith C H , Dietzler D N , Hanna T L 
Published: January 2020

Abstract
A column cation-exchange resin procedure for plasma ammonia was modified to require only 100 mul of plasma per determination. Mean analytical recovery of standard from resin (six samples) was 98% (range, 94-100%) as compared to a mean of 63% (range, 58-70) for nine samples when a batch cation-exchange procedure was used. Absorbance was proportional to sample concentration up to 800 mumol/liter. Analytical recovery of standard from plsma (six samples) was complete (mean, 103%; range, 90-113). Thirteen aliquots of a specimen of fresh plasma from a single adult individual gave a mean value of 20 mumol/liter (range, 11-26). The mean plasma venous ammonia concentration for 27 adults was 16 mumol/liter (range, 0-39), and for 15 newborns it was 60 (range, 34-102). Values for capillary plasma measured at the same time were higher, and we discuss possible explanations for this. Values are given for infants and children from one month to 14 years of age. Effects of storage time and temperature on plasma ammonia concentration are discussed.