bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simple method for estimating glycosylated hemoglobins, and its application to evaluation of diabetic patients.
Authors: Chou J , Robinson C A , Siegel A L 
Published: January 2020

Abstract
Recent reports have suggested that determination of glycosylated hemoglobin may serve as a clinical aid for long-term blood glucose control in diabetes mellitus. We describe a simple procedure for measuring it by ion-exchange chromatography. Hemolysates were subjected to Bio-Rex 70 chromatographic separation on small columns. Percentages in the normal group ranged from 4.7 to 8.8% of total hemoglobin; the mean +/- standard error was 6.61 +/- 0.31%. Values in the diabetic group ranged from 6.9 to 17.4%; the mean was 10.83 +/- 0.34. Plasma glucose concentrations after fasting, plotted vs. the percent of glycosylated hemoglobin, revealed a linear relationship at normal or moderately high glucose concentrations. However, the values for glycosylated hemolgobin approached a plateau with grossly higher plasma glucose concentrations after fasting. Our results support the view that, due to its long half-life, the estimation of glycoylated hemoglobin reflects the integrated glucose concentrations to which the erythrocytes have been previously exposed.
Thyroid hormone contamination in crystalline diiodotyrosine.
Authors: Alexander N M , Nishimoto M 
Published: January 2020

Abstract
Crystalline preparations of diiodotyrosine contain trace quantities of thyroxine that can be detected by several competitive radioassays and by chromatography on Sephadex. Spontaneous coupling of diiodotyrosine to thyroxine during iodination of tyrosine and coprecipitation of hormone with diiodotyrosine crystals are likely explanations for the trace contamination. We discuss the significance of these findings in relation to studies on the biosynthesis of thyroxine.
Determination of a trivariate reference region for free thyroxine index, free triiodothyronine index, and thyrotropin from results obtained in a health survey of middle-aged women.
Authors: Kågedal B , Sandström A , Tibbling G 
Published: January 2020

Abstract
We measured free thyroxine index, free triiodothyronine index, and thyrotropin in serum in a community survey of the female population 39--60 years old. A statistical method using Mahalanobis' distance was applied to the data, to identify and eliminate highly abnormal values, "outliers." There was a small but statistically significant increase in each of the three hormones with age. After correction for age dependency, significant but rather small correlations were found between the hormones. The material was used to calculate univariate reference intervals and a trivariate 0.95-tolerance region.
Modified erythrocyte uroporphyrinogen I synthase assay, and its clinical interpretation.
Authors: Piepkorn M W , Hamernyik P , Labbé R F 
Published: January 2020

Abstract
Assay of erythrocyte uroporphyrinogen I synthase is an accepted diagnostic test for acute intermittent porphyria, particularly in those individuals who are asymptomatic or in whom the disease is not biochemically manifested by excretion of excess porphyrin precursor. The assay described is based upon a coupled-enzyme procedure in which added delta-aminolevulinic acid and its dehydratase present in erythrocytes are used to generate porphobilinogen as substrate for uroporphyrinogen synthase. Zinc and dithiothreitol are added with preincubation to give maximum activity and reproducibility. These agents also prevent inhibition by lead. Healthy young women had a mean activity of 40 nmol of porphyrin formed per milliliter of erythrocytes per hour, men and activity of 38 nmol/ml/h. Preparation of control specimens is described. This assay gave within-day CVs ranging from 1.9 to 2.8%. Precautions in interpretation of results are discussed.
Characterization of the principal human prostatic acid phosphatase isoenzyme, purified by affinity chromatography and isoelectric focusing. Part II.
Authors: Vihko P 
Published: January 2020

Abstract
The principal enzyme of human prostatic acid phosphatase [orthophosphoric monoester phosphohydrolase (acid optimum), EC 3.1.3.2], which had been highly purified by affinity chromatography, isoelectric focusing, and gel filtrations, was shown to be homogeneous at pH 5.0 by sedimentation equilibrium analysis. The amino acid composition was determined and the sedimentation coefficient of the native molecule measured. The relative molecular mass was 89,000 at pH 5.0, as measured by analytical ultracentrifugation. The Km-value of the enzyme for p-nitrophenyl phosphate as substrate is 1.8-10(-4) mol/liter. I also examined substrate speificity, different inhibitors, and the effects of pH, temperature, and serum on the enzyme activity.
Gas--liquid chromatographic microdetermination of underivatized ethosuximide (alpha-ethyl-alpha-methyl succinimide) in plasma or serum.
Authors: Fellenberg A J , Pollard A C 
Published: January 2020

Abstract
A gas-liquid chromatographic procedure for the microdetermination of ethosuximide is described. Ethosuximide is extracted from acidified plasma or serum into chloroform containing an internal standard alpha,alpha-dimethyl-beta-methyl succinimide. Part of the initial chloroform extract is gently evaporated, the residue redissolved in n-heptane at 60 degrees C, and an aliquot analyzed by gas-liquid chromatography. The procedure is rapid, reliable, sensitive, and specific. It requires a 25--50 microliter sample for a single estimation, has a detection threshold of less than 10 micromol/liter, and is suitable for routine clinical use.
Distribution of thioridazine and its metabolites in human tissues and fluids obtained postmortem.
Authors: Dinovo E C , Bost R O , Sunshine I , Gottschalk L A 
Published: January 2020

Abstract
Thioridazine and metabolites were measured in brain, liver, and kidney specimens, obtained postmortem from two subjects whose deaths were related to acute intoxication with thioridazine, by gas-liquid chromatography. Although the absolute concentration measured for thioridazine and metabolites differed in the two cases, the metabolic pattern for each tissue, expressed in terms of the percentage of total drug in each tissue, was quite similar. The brain, liver, and kidney metabolic patterns, however, are in sharp contrast to the plasma metabolite patterns observed for subjects on a therapeutic regimen of thioridazine. As this example demonstrates, postmortem specimens are a valuable (but seldom used) source of human pharmacological data.
Plasma estriol vs. estrogen assays in 24-h urines as an index to fetal status.
Authors: Kirkish L S , Barclay M L , Parra J B , Compton A A , McCann D S 
Published: January 2020

Abstract
Conventionally, urinary estrogens are measured to monitor fetal well-being in the third trimester of pregnancy. There are many theoretical and practical advantages to the use of recently introduced plasma estriol assays; consequently, we undertook to compare the results of a spectrophotometric assay for total urinary estrogen with values for plasma total and free (unconjugated) estriol obtained by radioimmunoassay with commercially available kits. The data correlate well, r = 0.70 for plasma total estriol with urinary estrogen (expressed as milligrams of estrogens per gram of creatinine [E/C]), r = 0.79 for plasma free estriol with E/C, and r = 0.71 between the two plasma values. Minute-to-minute fluctuations during 90 min and day-to-day fluctuations followed during five days suggest that fluctuations of up to +/- 45% are within the normal range (means +/- SD of the day-to-day fluctuations were 16.9 +/- 7.7% and 15.6+/- 8.2%). Turn-around time is a minimum of 29 h for the urinary estrogen assay, 4.5 h for the plasma total estriol, and 3 h for the plasma free estriol.
Alternative mechanized method for analysis for inorganic phosphate without reduction.
Authors: Roberts N B 
Published: January 2020

Abstract
The mechanized measurement of inorganic phosphate in plasma can be achieved without reduction by only minor alterations to an existing continuous-flow reduction procedure. The method is based on the enhancement of the extinction of the phosphomolybdate complex by the detergent Triton X-100. Results obtained agree well with those obtained by the standard reduction (Fiske-SubbaRow) procedure. The correlation coefficient between the two methods was 0.996 and statistical analysis of the data confirmed very good agreement between the two sets of values.
Modified Jendrassik--Grof method for bilirubins adapted to the Abbott Bichromatic Analyzer.
Authors: Mori L 
Published: January 2020

Abstract
I describe a semi-micro method for use with a discrete analyzer, the Abbott ABA-100, requiring 75 microliter of sample for determination of both the total and direct bilirubins. This method utilizes a serum blank. It is simple and reasonably rapid. The azobilirubin formed by both the total and the direct bilirubins produces a reddish-violet color, which is measured at 550 nm. Values obtained are comparable to those by the automated Jendrassik and Grof procedure adapted by Gambino and Schreiber (total r = 0.999, direct r = 0.990). The method is linear to 300 mg/liter. Day-to-day precision (CV) for the total bilirubin was 8.8% for a 8 mg/liter sample (n = 45) and 4.7% for a 57 mg/liter sample (n = 46). The absorbance of hemoglobin and its derivatives (540 nm) caused a false decrease in the measured bilirubin content, the direct being more affected than the total. This problem was alleviated by the use of caffeine and acid blanks.
Mass-fragmentographic determination of catecholamine metabolites in amniotic fluid and its possible clinical usefulness.
Authors: Muskiet F A , Jeuring H J , Nagel G T , de Bruyn H W , Wolthers B G 
Published: January 2020

Abstract
We describe the determination of 3-methoxy-4-hydroxy-phenylacetic acid, 3-methoxy-4-hydroxyphenylamandelic acid, and 3-methoxy-4-hydroxyphenylethylene glycol in amniotic fluid by means of mass fragmentography, with use of deuterated internal standards. The results expressed in terms of absolute concentration and creatinine concentration, are given as a function of gestational age. In the 15th to 17th week, concentrations in amniotic fluid are a reflection of those in the mother's serum, whereas in the 32nd to 40th week, these concentrations, expressed in terms of creatinine, are similar to those found in the urine of newborns. We discuss the possible usefulness of the determination of catecholamine metabolites in amniotic fluid in the diagnosis of congenital neuroblastoma, maternal pheochromocytoma, and underdevelopment.
New enzymatic method for serum uric acid at 500 nm.
Authors: Trivedi R C , Rebar L , Berta E , Stong L 
Published: January 2020

Abstract
We describe a manual method, well suited to mechanization, for quantitating serum uric acid at 500 nm. In the assay mixture (0.10 ml of sample and 3.00 ml of reagent) the hydrogen peroxide produced from uric acid by uricase is coupled with p-hydroxybenzoate and 4-aminoantipyrine in the presence of peroxidase to form a colored complex, which is measured. A separate sample blank is obviated by taking an initial absorbance measurement 20 s after the sample is added. The reaction is complete within 5 min; its sensitivity is 0.001 deltaA/mg per liter. Absorbances are linearly related to uric acid concentrations up to 120 mg/liter. Many substances that may be present in normal serum do not interfere, but bilirubin in moderately above-normal concentrations will interfere. The procedure can be modified to largely correct for this, when necessary. The proposed method (y) correlated well (r = 0.979) with the uric acid 293 nm reference method (x) and the relation is described by the equation y = 0.998x + 2.42.
Bisalbuminemia. A new molecular variant, albumin Vancouver.
Authors: Frohlich J , Kozier J , Campbell D J , Curnow J V , Tárnoky A L 
Published: January 2020

Abstract
Of 18 members of a Fiji Indian family investigated, eight of the 12 males and two of the six females had an electrophoretically slow-type bisalbuminemia (alloalbuminemia). The albumin was characterized by the hiterto unique ratio of the two bands (Al A 35%: variant 65%), and by dye-binding studies and electrophoretic mobility in different media. The data suggest that this is a new variant, which we propose to call albumin Vancouver (Al Va).
High-performance liquid-chromatographic assay of aminoglycoside antibiotics in serum.
Authors: Anhalt J P , Brown S D 
Published: January 2020

Abstract
We describe procedures for the high-performance liquid-chromatographic assay of gentamicin, amikacin, and tobramycin in serum. The aminoglycoside antibiotic is extracted from serum by using a CM-Sephadex column and is measured by reversed-phase, ion-pair chromatography. Continuous-flow, post-column derivatization with o-phthalaldehyde is used to form fluorescent products for detection. An internal standard is used in each assay. Synthesis of 1-N-acetylgentamicin C1, the internal standard for the gentamicin assay, is described. For each procedure, concentration and instrument response are linearly related in the range of therapeutically important concentrations. The methods are precise and results correlate well with results obtained by bioassay. The between-day CV (n = 10) for each procedure was less than 4%. No substances have been detected in clinical specimens that interfere with these chromatographic procedures. The possible use of these methods for analysis for other aminoglycoside antibiotics is discussed.
High-performance liquid-chromatographic simultaneous determination of commonly used tricyclic antidepressants.
Authors: Proelss H F , Lohmann H J , Miles D G 
Published: January 2020

Abstract
We report a method for simultaneous measurement of five commonly used tricyclic antidepressant drugs (doxepin, desipramine, nortriptyline, imipramine, and amitriptyline) in serum by paired-ion high-performance liquid chromatography, with use of a reversed-phase column and ultraviolet detection at 254 nm. The drugs are extracted from 2 ml of serum at pH 14 into hexane/isoamyl alcohol (99/1 by vol) and re-extracted into 200 microliter of 0.1 mol/liter HCI. An aliquot of the aqueous acid phase is chromatographed with use of a methanol/acetonitrile/water (41/15/44) solvent system, containing 5 mmol of pentanesulfonic acid per liter of phosphate buffer (0.1 mol/liter, pH 6.5), at a flow rate of 1,5 ml/min. Analytical recoveries of the drugs from serum increase with increasing concentration, from 62% at 25 microgram/liter to 93% at 300 microgram/liter. Linear response is observed for drug concentrations up to 1500 microgram/liter and the detection limit is 2-3 microgram/liter. Within-run precision ranges from 1.4 to 2.9% and day-to-day precision from 1.7 to 7%, depending on the specific drug. The entire procedure can be completed within 45 min and is well adapted to the routine clinical laboratory. Of 48 common basic and several neutral drugs tested for possible interferences, only three benzodiazepines, three phenothiazines, and three antihistamines interfere with the assay of doxepin, desipramine, and nortriptyline, respectively.
Effect of in vitro hemolysis on chemical values for serum.
Authors: Frank J J , Bermes E W , Bickel M J , Watkins B F 
Published: January 2020

Abstract
Hemolysis in serum specimens is commonplace. This study examines the effect of hemolysis on results of selected chemical assays. Hemolysis was simulated by adding hemolysate to serum to give hemoglobin concentrations of 90 to 2800 mg/liter and a rating by technologists of 0 to 4 + hemolyzed. The effect of hemolysis on values for some serum constituents, particularly acid phosphatase and creatine kinase, was shown to be method dependent. Not unexpectedly, hemolysis most affects results for lactate dehydrogenase.
Continuous-flow enzymic method evaluated for measurement of serum triglycerides with use of an improved lipase reagent.
Authors: Whitlow K , Gochman N 
Published: January 2020

Abstract
We compared a modified enzymic continuous-flow method for serum triglycerides, in which a microbial lipase is used without protease, to an extraction-fluorometric method. Results (for total--blank) correlated well with those by the comparison procedure: enzymic = 1.002 fluorometric--14 mg/liter; r = 0.9968. Serum blanks were measured for each sample in both methods, and the concentration of free glycerol measured by the enzymic method was shown to be as much as 15 to 71% of the total triglyceride result in 7% of the samples analyzed. The dual-channel continuous-flow system provides automatic free-glycerol blank subtraction for the enzymic method.
Measurement of plasma nortriptyline concentrations: radioimmunoassay and gas-chromatography compared.
Authors: Robinson J D , Braithwaite R A , Dawling S 
Published: January 2020

Abstract
We compared measurement of plasma nortriptyline by a recently developed radioimmunoassay technique with values obtained by traditional gas chromatography. The coefficient of correlation (r) was 0.98 for 84 samples from 21 controlled patients; for a separate series of 45 samples from 34 patients who were receiving in addition other medication, r was 0.96. Use of radioimmunoassay in the routine determination of plasma nortriptyline concentration is discussed.
Continuous-flow analysis for serum albumin, by use of the immediate reaction with bromcresol green.
Authors: Plesher C J 
Published: January 2020

Abstract
Albumin reacts with bromcresol green reagent almost immediately, other serum proteins more slowly. This phenomenon can be exploited to improve the specificity of this routine method for determining serum albumin. I describe a 30-s reaction as adapted to continuous-flow analyzers, with no interference from other serum proteins. The method shows linearity to 72 g/liter. Results of this method correlate very well with those by the Laurell "rocket" and manual (30-s) bromcresol green methods. This procedure gives a considerable improvement in specificity for continuous-flow analyzers as compared with current bromcresol green methods.
Enzymatic determination of plasma ammonia: evaluation of Sigma and BMC Kits.
Authors: Pesh-Imam M , Kumar S , Willis C E 
Published: January 2020

Abstract
We compared two kit methods for the enzymatic determination of plasma ammonia. The procedures involved measuring the decrease in absorbance at 340 nm resulting from the consumption of NADH in the Sigma kit, NADPH in the BMC kit. Both kits gave acceptable results for aqueous samples, but for plasma specimens values with the Sigma kit significantly exceeded those obtained with the BMC kit. In our hands, values with the BMC kit were more accurate and precise. On the basis of these results, we conclude that the BMC kit is the better choice.
Automated development of a kinetic method for the continuous-flow determination of creatinine.
Authors: Olansky A S , Deming S N 
Published: January 2020

Abstract
A "stopped-flow" method for the kinetic Jaffé determination of creatinine was developed, with the use of a computer-controlled continuous-flow system. Simplex optimization was used to find conditions of hydroxide and picrate giving maximum sensitivity for creatinine. We used a modified central composite experimental design to evaluate creatinine sensitivity and albumin, glucose, and acetone interferences as functions of hydroxide and picrate concentrations. More importantly, this work illustrates that the automated development of clinical chemical methods offers an efficient means of obtaining optimized, well-understood analytical procedures for subsequent routine use in the clinical chemistry laboratory.
Evaluation of a new multichannel analyzer, "Astra-8".
Authors: Finley P R , Williams R J , Lichti D A , Thies A C 
Published: January 2020

Abstract
We evaluated a new multiple-channel chemistry analyzer, the Beckman "Astra-8," which is controlled by a microprocessor with 52K bytes of memory. The instrument we tested performed the following tests: Na, K, CO2, chloride, urea nitrogen, glucose, and creatinine. We compared the Astra-8 to a continuous-flow (SMA 6/60) and a discrete (Du Pont aca, urea nitrogen only) analyzer. The Astra-8 demonstrated excellent precision, linearity, accuracy, analytical recovery, lack of interference, ease of operation, and satisfactory comparison to values obtained by the comparison methods.
Interlaboratory comparison of results of erythrocyte protoporphyrin analysis.
Authors: Jackson K W 
Published: January 2020

Abstract
Each of 65 laboratories analyzed 10 whole-blood samples for erythrocyte protoporphyrin by one or more of several analytical procedures. These procedures were of two types: (a) extraction of protoporphyrin from the erythrocytes into ethyl acetate/acetic acid, re-extraction into hydrochloric acid, and fluorometric measurement; or (b) direct reading in a portable fluorometer (hematofluorometer), with no pretreatment of the blood sample. Interlaboratory correlation was generally poor, especially between laboratories using extraction procedures. Hematofluorometric results intercorrelated better, but they had a low bias as compared to the extraction approach. Nationwide standardization of the test is required to assure satisfactory interlaboratory performance and to identify laboratories whose results are sufficiently accurate to be used for interpretations according to guidelines set forth by the Center for Disease Control for erythrocyte protoporphyrin testing.
Interference by tubing material in continuous-flow systems.
Authors: de Jong E B , Goldschmidt H M , Loog J A , van Alphen C C 
Published: January 2020

Abstract
An anomalous behavior in the measurement of calcium with the smac multi-channel high-speed analyzer was eliminated by taking the diluted serum directly from the dilution loop of the instrument before it enters the stainless-steel riser.
High-density lipoproteins estimated by an enzymatic cholesterol procedure, with a centrifugal analyzer.
Authors: Ash K O , Hentschel W M 
Published: January 2020

Abstract
We describe an assay for high-density lipoprotein cholesterol, adapted to a centrifugal analyzer, the GEMSAEC System 3, which includes use of an increased Mn2+concentration (91 mmol/liter) [J. Lipid Res. 19, 65 (1978)] and ethylenediaminetetraacetate [Clin. Chem. 22, 98 (1976)]. Modifications to the GEMSAEC system include reducing the mixing burst and preconditioning the sample tip. Accuracy of this procedure, as assessed by analysis of a control pool from the Center for Disease Control, was 99.2%. Day-to-day precision for two control pools was 320 +/- 13 and 506 +/- 17 mg/liter. Serum sample volume was decreased to 0.5 ml. In blanks with heparin/Mn2+ present, the pseudocholesterol concentrations resulting from a reaction of the enzymatic cholesterol reagent and the heparin/Mn2+ precipitating reagent depend on the source of the enzymatic reagent and appear to be enhanced slightly by the use of ethylenediaminetetraacetate. Pseudocholesterol concentrations reach a maximum at heparin/Mn2+ concentrations well below those needed to completely precipitate the low-density and very-low-density lipoprotein fractions. Population reference values were obtained from analyses done on 224 local physicians (mean: male, 500 mg/liter; female, 620 mg/liter) and 156 ambulatory patients (mean: male, 463 mg/liter; female, 553 mg/liter).