bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved staining characteristics of serum lipids after halogenation and esterification of thin-layer chromatograms.
Authors: Nelson W R , Natelson S 
Published: January 2020

Abstract
We describe a procedure for treatment of thin-layer chromatographic serum lipid patterns so that they may be stained by dyes for evaluation by densitometry. After development of the chromatogram [Clin. Chem. 18, 384 (1972)] the plates are dried and sprayed with butyryl chloride. This esterifies the free cholesterol. After drying, the plate is treated with iodine monobromide, to add iodline to the double bonds. The triacylglycerols (triglycerides), cholesterol esters, free cholesterol, and phospholipids are now all in the form of esters with no unsaturated double bonds. The free fatty acids are also now saturated. The chromatogram is now stained with basic fuchsine in acetate buffer (0.1 mol/liter, pH 5.0). Excess stain is removed with a buffered solution of guanidine hydrochloride. Erythrosine B may also be used. With basic fuchsine the background will be a uniform pink. With erythrosine B the background is white, but the stain tends to be washed out of the free fatty acids. The chromatograms are evaluated by densitometry, with use of a 540-nm filter for basic fuchsine and a 520-nm filter for erythrosine B. The stained chromatograms and densitometric scans accurately represent the relative concentration of the various lipid fractions as compared to that of an internal standard, and correlate with the nature of the disease being explored.
Sequential-saturation-type assay for serum 25-hydroxyvitamin D.
Authors: Ellis G , Dixon K 
Published: January 2020

Abstract
We describe a method for measuring 25-hydroxyvitamin D in serum. The serum is denatured with ethanol, and the extract purified by chromatography on silicic acid to prevent potential interference from vitamin D and by other substances. 25-Hydoxyvitamin D is assayed by sequential saturation analysis in Tris-HCI buffer, pH 8.6, containing the surfactant Triton X-405 (2 ml/liter) to solubilize the steroid. Diluter, unpurifed normal human serum is used as the binder. The method is sensitive and precise. The dose-response curve is linear. The assay normally gives high count rates (12 000 to 20 000 cpm for the zero standard) and consequently 25-hydroxyvitamin D of low specific activity can be used if necessary. Serum 25-hydroxyvitamin D was determined in normal and osteomalacic subjects.
Computer-assisted quality control in clinical chemistry.
Authors: Sher P P 
Published: January 2020

Abstract
A MUMPS comuter program, which stores and retrieves quality-control data from all automated and manual work-station in the laboratory, has been developed as part of a laboratory information system. Tabular displays, Levey-Jennings charts, and summary statistics are available on a real-time basis. Significant economy over previous manual methods has been observed, and the total quality-control program in the laboratory has become a more active and timely process.
Triiodothyronine uptake assay with immobilized triiodothyronine antibody as the bound-free separating agent.
Authors: Coleman L H , LeMat B , Diel V , Barbieri A , Barrett J 
Published: January 2020

Abstract
Available systems for evaluation of degree of unsaturation of thyroxine-binding globulin are hampered at the bound-free separation step. In current assays, inorganic sorbants or ion-exchange resins are used to separate free 125I-labeled triiodothyronine from that bound to thyroxine-binding globulin. The techniques are laborious, time consuming, and not readily adaptable to total automation. In the assay we describe, triiodothyronine antibody, immobilized on the walls of polypropylene test tubes, is used as the bound-free separating agent in the evaluation of degree of unsaturation of thyroxine-binding globulin. The assay is simplified to four steps; washing, centrifugation, and use of columns are eliminated; and the procedure is readily automatable with existing pipetting equipment. Correlation with existing methods is excellent.
Furildioxime method for nickel analysis in serum and urine by electrothermal atomic absorption spectrometry.
Authors: Mikac-Dević D , Sunderman F W , Nomoto S 
Published: January 2020

Abstract
We describe a method of analysis for nickel in serum and urine. After the sample (1 ml) has been subjected to acid digestion, Ni(II) is extracted into methylisobutylketone as a furildioximate complex, and is measured by electrothermal atomic absorption spectrometry. The method is more sensitive and more convenient than previous methods, and is less subject to nickel contamination because the digestion and extraction steps are performed in a single tube. Analytical recovery of Ni(II) (10 or 20 microng/liter) added to 20 specimens of serum or urine averaged 101% (range, 94 to 107). The following values (mean +/- SD) were obtained for nickel concentrations in specimens of serum and urine from 19 healthy adults living in central Connecticut: serum = 3.1 +/- 1.6 microng/liter; urine = 2.7 +/- 1.6 microng/liter. The method provides a practical means for monitoring occupational exposures of workers to nickel compounds.
Binding of dye to albumin, as studied by ultrafiltration.
Authors: Yap W , Schaffer R 
Published: January 2020

Abstract
We describe a procedure for measuring the binding of small molecules to proteins by means of a dynamic ultrafiltration system. A continuous binding curve is obtained by continuously monitoring the absorbance of ultrafiltrate as a function of ultrafiltrate volume, and corrections are made for the retention of the small molecule by the membrane and the leakage of the protein through the membrane. The method is applied to the binding of bromcresol green to human albumin. Some major sources of uncertainties in the method are discussed.
Increased concentrations of serum free fatty acids falsely increase serum thyroxine as determined by competitive protein-binding.
Authors: Pannall P R , Swanepoel E , Bennett J M , Pauw F H 
Published: January 2020

Abstract
Markedly increased concentrations of free fatty acids after a fatty meal and heparin injection already have been shown to falsely increase thyroxine values measured by competitive protein-binding techniques, where ethanol extraction in used. We report here the effect of lesser increases. In 10 patients receiving heparin during hemodialysis we found significant increases in serum thyroxine by competitive protein-binding (mean, 20 nmol/l) and in free fatty acid concentrations (164 micronmol/l). Thyroxine measured as iodine did not change significantly. In seven subjects who had fasted for 27 h, we also noted significant increases in thyroxine by competitive protein-binding (mean 63 nmol/l) and in free fatty acid concentrations (624 micronmol/l). In a single subjects, serial measurements showed a close association of the two variables and the overall correlation between the increases was good. This artefact limits the value of many currently used thyroxine methods because it imposes restrictions on transport of samples and selection of patients.
Evaluation of a discrete samples/stopped-flow mixer system for equilibrium and kinetic analyses.
Authors: Pardue H L , Gaw H T , Mieling G E , Mathews V L , Fast D M , Rubesch M A 
Published: January 2020

Abstract
This paper describes the evaluation of a system for computer-controlled discrete sampling and stopped-flow mixing for equilibrium and kinetic determinations of several sorts of analytes in human serum. The instrumental system features a wash-out sampling system that permits rapid change-over from one sample and (or) reagent type to another, and a mixing-measurement system that can provide reliable data as soon as 10 ms after reagent and sample are mixed. Examples discussed include equilibrium procedures for glucose and cholesterol, slow kinetic procedures for glucose and lactate dehydrogenase, and a fast kinetic method for thiocyanate. The regression equation for all stopped-flow results (n = 114) vs. results by conventional methods is y = (103 +/- 0.01)x - (0.016 +/- 0.019) for numerical values of y between 0.3 and 3.0. The correlation coefficient for these data was 0.991. These results demonstrate that the stopped-flow method is a viable analytical approach for equilibrium, slow kinetic, and fast kinetic determinations that require measurement times shorter than 0.1 s.
Analysis for platinum in biological material by flameless atomic absorption spectrometry.
Authors: Pera M F , Harder H C 
Published: January 2020

Abstract
A method for determining platinum in biological materials by flameless atomic absorption spectrometry has been developed for use in pharmacological studies of platinum antitumor compounds. Tissue digests are analyzed in a heated graphite atomizer, with use of background correction and ramp temperature charring. We have overcome problems of apparent loss of platinum in Pt-supplemented tissue samples with time and of difficulty in analyzing tissue lipid. The validity of the assay was verified by injecting rats with radiolabeled cis-dichlorodiammineplatinum (II), then measuring platinum in tissues by gamma scintillation spectrometry and flameless atomic absorption spectrometry. Correlation between the two methods was excellent. The limit of the assay in its present form is about 0.1 migrogram/gram of wet tissue.
Continuous-flow determination of dialyzable calcium in serum.
Authors: Toffaletti J , Savory J , Gitelman H J 
Published: January 2020

Abstract
We describe a procedure for measuring dialyzable calcium in 60 sera per hour with use of AutoAnalyzer (Technicon) modules. The serum is buffered, then dialyzed in a regular 6-inch (15-cm) dialysis block. A constant proportion of the dialyzable calcium is fluorometrically measured. Analysis of samples containing protein, prepared by an equilibrium dialysis technique, shows that protein-bound calcium is not detected. The method requires less than 0.4 ml of serum, and is accurate, precise, and durable. No unusual care or special techniques are required during sample collection or analysis.
Determination of urinary normetanephrine, metanephrine, and 3-methoxytyramine by liquid chromatography, with amperometric detection.
Authors: Shoup R E , Kissinger P T 
Published: January 2020

Abstract
We describe a sensitive procedure for measuring the basic catecholamine metabolites--normetanephrine, metanephrine, and 3-methoxytyramine--in urine by use of liquid chromatography, with electrochemical detection. These substances are isolated from hydrolyzed urine by passage through small ion-exchange columns and then pre-concentrated by a rapid set of solvent extractions before being injected onto the liquid-chromatographic column. Concentration and instrumental response are linearly related to 2.0 mg/liter for all three compounds, and practical lower detection limits are about 20 micrograms/liter for actual urine samples. The high selectivity that accrues from the combination of the extraction procedure, high-performance liquid chromatography, and electrochemical detection makes this procedure suitable for quantitative studies of catecholamine metabolism. A set of six samples can be taken through the extraction procedure in parallel in less than 2 h; once prepared, the extracts can be analyzed at a rate of three per hour.
Continuous-flow determination of serum inorganic phosphate with a single reagent--the vanadomolybdate method re-evaluated.
Authors: Baadenhuijsen H , Seuren-Jacobs H E , Jansen A P 
Published: January 2020

Abstract
The merits of the vanadomolybdate method in the determination of inorganic phosphate are highly underestimated with regard to the simplicity of the method and the stability of both the reagents and the color that is formed. The absorption curve of the phosphovanadomolybdate complex, with its maximum at 335 nm, extends into the visible range of the spectrum. This permits measurements with inexpensive tungsten-lamp colorimeters. On-stream dialysis is best done in a nitric acid medium, 0.15 mol/liter. Paralleled by the change in the H2PO4-/H3PO4 ratio, appreciable protein binding and poor dialysis efficiency are seen at lower acid concentrations (pH greater than 1.0). Optimum reaction-mixture concentrations of vanadium and molybdenum appeared to be respectively 0.2 and 5 mmol/liter up to 3 mmol of phosphate per liter, in a final acid medium of 0.2 mol/liter, concentrations considerably lower than those used in some studies published earlier. Color development with the stable combined reagent is complete after only 20 s at room temperature and the color is stable for at least 2 h. Figures on precision and accuracy demonstrate the reliability of the method.
Simultaneous measurement of phenobarbital, phenytoin, primidone, ethosuximide, and carbamazepine in serum by high-pressure liquid chromatography.
Authors: Kabra P M , Stafford B E , Marton L J 
Published: January 2020

Abstract
We present a method for simultaneously determining five anticonvulsants [phenobarbital, phenytoin (diphenylhydantoin), primidone, ethosuximide, and carbamazepine] in as little as 25 microliters of serum. The proteins are precipitated with an acetonitrile solution containing hexobarbital as an internal standard. The anticonvulsants are eluted from a reversed-phase column with a mobile phase consisting of an acetonitrile/phosphate buffer (19/81 by vol) at a flow rate of 3.0 ml/min. The eluted drugs are detected by their absorption at 195 nm, and quantities estimated from their peak heights. Each analysis requires about 14 min. at an optimum column temperature of 50 degrees C. The lower unit of detection for all of these drugs is less than 10 ng. Sensitivities, for serum samples, of 1.0 mg/liter for all the drugs analyzed are attained routinely. Analytical recoveries for the five drugs varied from 97 - 107%, with good day-to-day precision (CV between 3.9 and 5.9%). Of more than 30 drugs tested for possible interference, only ethotoin interferes with the analysis of phenobarbital.
Creatine kinase isoenzyme activity in human placenta and in serum of women in labor.
Authors: Laboda H M , Britton V J 
Published: January 2020

Abstract
Creatine kinase (EC 2.7.3.2) isoenzymes in extracts of human placenta and in serum from nonpregnant women and women in labor were separated on columns containing diethylaminoethyl-cellulose and assayed. The distribution of the isoenzymes in placenta (n = 10) was 80% BB (200 +/- 66 U/g (wet weight), 19% MM (49 +/- 30 U/g), and 1% MB (2.6 +/- 1.7 U/g); The geometric mean for the serum BB activity of the nonpregnant women (n = 50) was 0.6 +/- 1.5 U/liter, as compared to 3.0 +/- 1.4 U/liter for patients in labor who had normal deliveries (n = 92). The arithmetic mean for serum BB activity of labor patients with induced labor (n = 20), premature labor (n = 7), cesarian section (n = 6), or hypertension and pre-eclampsia (n = 6) did not differ significantly from the arithmetic mean BB activity for serum of labor patients with normal deliveries. However, the arithmetic mean serum BB activity of patients with stillbirths (n = 7) was significantly smaller than the arithmetic mean for normal labor patients.
Measurement of free thyroid hormones in serum by dialysis and gas chromatography.
Authors: Petersen B A , Giese R W , Larsen P R , Karger B L 
Published: January 2020

Abstract
We describe a simultaneous, absolute analysis for free (dialyzable) triiodothyronine and thyroxine in serum by the sequence: dialysis, internal standard addition to the dialysate, cation-exchange chromatography, derivatization, and gas chromatography with electron capture detection. The detection limit is 0.2 pg and the precision (repeatability) in the range of 4 to 20 ng/liter is 1.6%. Mean values for free T3 and T4 in 29 euthryoid sera were 4.2 and 18.9 ng/liter, respectively, in close agreement with accepted values. Correlation coefficients for the two compounds were 0.99 and 0.97, respectively, when this procedure was compared with a method involving tracer dialysis and radioimmunoassay. A chromatographic peak was seen for free 3,3',5'-triiodothyronine in the analyses of two of eight hyperthyroid sera, and, with a larger sample volume, from a euthyroid serum. The new method is a potential reference and research procedure for analysis of free iodothyronines.
Recent developments in the clinical assessment of the metabolism of aromatics by high-performance, reversed-phase chromatography with amperometric detection.
Authors: Kissinger P T , Bruntlett C S , Davis G C , Felice L J , Riggin R M , Shoup R E 
Published: January 2020

Abstract
High-performance liquid chromatography with electrochemical detection has developed into a tool with excellent capability to monitor picomole amounts of individual metabolites in both tissue and body-fluid specimens. Significant technical advances in the area of microparticle chemically-bonded stationary phases have led to dramatic improvements in both sensitivity and resolution. Reversed-phase systems can be modified to include charged exchange sites by addition of detergents to the mobile phase. Adjustment of the surface charge in this manner permits capacity factors for ionic sample components to be increased or decreased. This concept is quite compatible with electrochemical detection and has provided the foundation for several clinical assays now in routine use. Examples of additional applications are presented for the determination of catecholamines in tissue, 3-methoxy-4-hydroxyphenylglycol in urine, and dopamine-beta-hydroxylase activity in human serum.
A rate nephelometer for measuring specific proteins by immunoprecipitin reactions.
Authors: Sternberg J C 
Published: January 2020

Abstract
A kinetic nephelometric method and instrument have been developed for the rapid determination of specific serum proteins by means of immunoprecipitin reactions. The maximum rate of change of scattered light intensity in an antigen-antibody reaction can be made to occur within 60 s after initiation of the reaction and provides a measure of the antigen concentration under antibody excess conditions. A mathematical relationship has been found for the conversion of the nonlinear maximum rate data directly into a linear concentration read-out, making possible the use of single-point calibration. Instrument operating parameters and computations are programmed for a particular analysis by means of machine-readable cards. Antigen-excess samples are detected rapidly by injection of calibrator into the reaction mixture after the rate signal has dropped to a pre-selected level. The method correlates well with both radial immunodiffusion and end-point nephelometric methods.
Assay procedures for polyamines in urine, serum, and cerebrospinal fluid.
Authors: Seiler N 
Published: January 2020

Abstract
Putrescine (1,4-diaminobutane) and the polyamines spermidine and spermine have attracted interest as possible markers of malignancy and of response to chemotherapy. The assay methods currently in use for these amines are reviewed and compared in respect to sensitivity, reproducibility, and applicability to routine analysis for them in urine, blood, and cerebrospinal fluid.
Determination of acetaminophen concentrations in serum by high-pressure liquid chromatography.
Authors: Horvitz R A , Jatlow P I 
Published: January 2020

Abstract
We describe a method for determination of serum acetaminophen concentrations in serum by reversed phase high-pressure liquid chromatography. The homolog N-propionyl-p-aminophenol was used as an internal standard. The procedure, which requires only a single extraction with diethyl ether, can be optimized to be linear over the ranges of 10 to 100 or 1 to 20 mg/liter. Within-run CV was 1.2%; between-run CV was 4.4% and 4.9% at two different concentrations. Many commonly used drugs were tested and found not to interfere. The procedure is simple and rapid enough for use on an emergency basis in cases of overdosage, and can be optimized for measurement of either therapeutic or toxic concentrations.
An automated competitive binding procedure for measuring thyroxine in serum.
Authors: Hofman L F , Bouley A M , Barron E J 
Published: January 2020

Abstract
A competitive binding assay for serum thyroxine has been automated, with the use of small, reusable Sephadex columns to separate thyroxine from endogenous thyroid-binding globulin and later to separate the bound and free thyroxine. Sixty samples an hour are run through columns, which are held in an aluminum turntable rotated by a fraction collector motor. Reagents and samples are fed to the columns by a proportioning pump. Waste eluates are collected and drained to the sink by a Teflon tray positioned between the columns and counting tubes, also held by the turntable. A cut out area in the tray allows one to collect the bound fraction, which can then be counted in a scintillation counter. Values are calculated and printed by a desk calculator interfaced with the scintillation counter. The "day-to-day" CV for this method is 5%. The accuracy is satisfactory when tested by comparison with other methods, by recoveries, and by linearity of dilutions.
Simultaneous radioimmunoassay of thyrotropin and thyroxine in human serum.
Authors: Bluett M K , Reiter E O , Duckett G E , Root A W 
Published: January 2020

Abstract
The importance of early diagnois and treatment of congenital hypothyroidism has been well established, and several screening programs have been undertaken to detect neonates with this disorder by measurement of concentrations of thyrotropin or thyroxine in the serum. However, measurement of either hormone alone may fail to identify all affected patients. Accordingly, we have established a simultaneous double-antibody, dual-isotope radioimmunoassay for both. Sensitivity, slope, analytical recovery, and precision characteristics of the simultaneous assay do not differ from those of each assay performed separately. Values for the two analyses in the single and simultaneous assays correlate well (r = 0.951 for thyroxine, 0.983 for thyrotropin). This assay system permits determination of both hormones within 72 h after specimen collection and thus should allow more rapid evaluation, diagnosis, and treatment of infants with congenital hypothyroidism.
Plasma free amino acid patterns in pregnancy: relationships to gestational age and applications to detection of fetal distress.
Authors: Schoengold D M , deFiore R H 
Published: January 2020

Abstract
Data on free amino acids in serial samples of plasma from 15 pregnancies from 14 women have been compared to data from normal nonpregnant women by use of pattern-recognition program. The overall amino acid patterns were found to be a reproducible function of gestational age. Two samples from a woman with a pregnancy terminated by a spontaneous abortion were clearly resolved from all the other samples by this procedure.
High-performance liquid chromatographic assay for 25-hydroxyvitamin D3 in serum.
Authors: Gilbertson T J , Stryd R P 
Published: January 2020

Abstract
We describe a precise and specific method for measuring 25-hydroxyvitamin D3 in 1 ml of human serum. Extraction with chloroform/methanol followed by chromatography on a 0.5 X 2-cm silica gel column yields a sample that is sufficiently free of extraneous material for high-performance liquid chromatography on a column of microporous silica gel (10 micron average particle diameter). The measurement is not influenced by vitamins D2 or D3, 25-hydroxyvitamin D2, or any of the more hydroxylated metabolites of the vitamin D group. Results by this method correlate well with a competitive protein-binding assay (r = 0.961), but with a negative bias of 6.9 +/- 3.3 microgram/liter. We measured concentrations of 25-hydroxyvitamin D3 in serum drawn during February from 24 persons who were judged normal by physical examinations. The range was 5.5-23.8 microgram/liter (mean, 15.0 +/- 5.2 microgram/liter). The day-to-day CV for the assay was 5.46%.