bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isoelectric focusing of gamma globulins in cerebrospinal fluid from patients with multiple sclerosis.
Authors: Trotter J L , Banks G , Wang P 
Published: January 2020

Abstract
The technique of isoelectric focusing has been adapted for rapid clinical analysis for globulins in cerebrospinal fluid with use of commercially prepared horizontal-slab acrylamide gels. The globulin fraction is concentrated by ammonium sulfate precipitation, which allows more of the relevant protein to be applied, use of a wider range of total protein concentrations, and higher resolution than is true for previously described methods. Critical variables include a constant concentration and volume of IgG, a constant low temperature of the acrylamide gel, and sensitive staining with Coomassie Brilliant Blue G-250. The apparatus used is adaptable for other electrophoretic procedures in the clinical laboratory, and the use of commercially prepared gel slabs is more convenient, more reproducible, and requires less time than other methods.
Effectiveness of an outpatient urine screening program.
Authors: Fraser C G , Smith B C , Peake M J 
Published: January 2020

Abstract
We evaluated the effectiveness of a routine outpatient urinalysis screening program on a sample population of 2600 patients. The 189 abnormal urine results found in 182 patients were followed up by study of any new clinical and laboratory investigations or therapeutic modifications initiated on the basis of any abnormal test result. The urinalysis screening program appeared to have significant bearing on diagnosis or treatment in only 13 patients. Abnormalities found in 150 of the 182 patients were either not noted or no further positive action was taken. Thus we concluded that under the conditions of this study the urine screening program added to hospital costs without significant benefit to the patient.
Influence of salts on Michaelis-constant values for NADH.
Authors: Howell B F , McCune S , Schaffer R 
Published: January 2020

Abstract
We previously observed [Clin. Chem. 22, 1648 (1976)] that values of the Michaelis constant for NADH for the conversion of pyruvate to lactate with lactate dehydrogenase (EC 1.1.1.27) in the presence of 0.1 mol/liter buffers at 25 degrees C showed first-order dependence on enzyme concentration. This is now recognized to be the result of an inhibitory influence exerted by buffers [NH4HCO2, tris(hydroxymethyl)aminomethane, and phosphate] and salts [(NH4)2SO4 and NaCl] present in the reaction mixtures. Inhibition constants for the enzyme/inhibitor complexes formed with these substances are about 0.3 mol/liter for competition of NH4HCO3 with NaOH and 0.4 mol/liter for competition of NH4HCO3 with pyruvate; they are 0.6 mol/liter for NaCl, 1.0 mol/liter for sodium phosphate, 0.3 mol/liter for (NH4)2SO4, and 0.8 mol/liter for tris(hydroxymethyl)aminomethane when these substances compete with NADH. Because of the large molar ratio of buffer to substrate (about 10(9):1) in enzymatic assays, the buffer concentration significantly influences the Michaelis constant, despite the large value for the inhibition constant. Attention to the concentrations of these substances may be required for decreasing variability in clinical assays in which lactate dehydrogenase and possible other enzymes are used.
Measurement of free-circulating cis-dichlorodiammineplatinum(II) in plasma.
Authors: Bannister S J , Sternson L A , Repta A J , James G W 
Published: January 2020

Abstract
Dichlorodiammineplatinum(II) is an anti-neoplastic agent that is currently undergoing clinical evaluation. We describe an analytical method for monitoring the free drug (or its breakdown products) in plasma. The method is able to distinguish between free and protein-bound drug. Plasma samples are deproteinized by centrifugal ultrafiltration. The platinum in the ultrafiltrate is converted to a cationic species by reaction with ethylenediamine and then collected on paper impregnated with cation-exchange resin. This process concentrates the samples, increases the stability of the platinum compounds (by removing the compound from solution), and places the sample in a uniform matrix of minimum thickness, which maximizes detection capabilities. Platinum was measured directly on the ion-exchange disks by X-ray fluorescence. The detection limit for free drug is 240 microgram/liter of plasma at the 3s level and fluorescence intensity is linearly related to drug concentration in the range from 570 to 5700 microgram/liter.
Serum gentamicin assay by high-performance liquid chromatography.
Authors: Maitra S K , Yoshikawa T T , Hansen J L , Nilsson-Ehle I , Palin W J , Schotz M C , Guze L B 
Published: January 2020

Abstract
We describe a high-performance liquid chromatographic method for the quantitative determination of gentamicin in serum. The antibiotic was separated from serum by passage through a silicic acid column, derivatized with o-phthalaldehyde, and eluted with ethanol. The derivatized gentamicin was then separated into all three of its major components by reversed-phase chromatography and quantified by fluorometry. Concentrations in serum as low as 0.5 mg of gentamicin per liter could be accurately determined. A standard curve showed a linear response for serum containing gentamicin at concentrations ranging from 0 to 20 mg/liter. Tobramycin, amikacin, ampicillin, penicillin G, methicillin, carbenicillin, chloramphenicol, clindamycin, and cephalothin did not interfere with the gentamicin assay. Comparison with an accepted microbiological assay yielded a correlation coefficient of 0.99. This chemical assay is rapid (less than 30 min), sensitive, accurate, specific, and appears to be applicable to other aminoglycosides.
Use of an enzymatic kit method for cholesterol, designed for continuous-flow instrumentation, with discrete bichromatic and centrifugal analyzers.
Authors: Levinson S S 
Published: January 2020

Abstract
I examined a cholesterol-assay kit ("Autoflo", Biodynamics/bmc) designed for use with continuous-flow instrumentation for its use with some discrete analyzers. At pH 7.2, color develops within 3 min upon exposure to cholesterol, then begins to fade. At pH 8, the color develops more slowly but remains stable for at least 15 min after reaching a maximum. A pH 8.8, the color develops still more slowly and standards and patients' sera behave differently. Reagent at pH 7.2 is preferred because assays can be completed most rapidly, but pH 8 reagent must be used with instruments requiring longer periods of incubation. Cholesterol assays can be performed accurately, rapidly, reproducibly, and at low cost with an Abbott ABA-50 and pH 7.2 reagent or with a Gemeni Centrifugal Analyzer and the pH 8 reagent.
Determination of placental estriol in urine by gas-liquid chromatography, with equilenin as internal standard.
Authors: Gotelli G R , Kabra P M , Marton L J 
Published: January 2020

Abstract
Placental estriol in urine can be determined by rapid enzymatic hydrolysis, extraction with neutral XAD-2 resin, and quantitation by gas-liquid chromatography, with equilenin as the internal standard. Glucose, methenamine mandelate, hydrochlorothiazide, phenolphthalein, or salicylate do not interfere. Analytical recovery of estriol added to urine was 92-108%. Day-to-day precison (CV), established by 15 repilicate analyses at a mean concentration of 21.3 mg/liter, was 6.6%.
History and Background of Protoporphyrin Testing
Authors: Labbé Robert F 
Published: January 2020

Abstract
Lead intoxication was first associated with increased coproporphyrin excretion almost 100 years ago; but not until the 1930's were abnormalities in blood protoporphyrin detected. These later findings have been interpreted as an inhibition by lead of iron incorporation into protoporphyrin during heme synthesis. The testing and application of this hypothesis had to await three more decades of research during which porphyrin/heme biosynthesis was elucidated, control of the pathway was intensively studied, and methodology was greatly improved. The heme biosynthetic pathway is uniquely affected by lead at several sites. These toxic effects can be manifested as increased coproporphyrin and δ-aminolevulinate excretion, decreased erythrocyte δ-aminolaevulinate dehydratase activity, and increased erythrocyte protoporphyrin concentration, all of which have been used and promoted as diagnostic tests for lead intoxication. Among these, the last appears to be becoming the test of choice. The historical background of this development is discussed from a biochemical viewpoint.
Simpler flame photometric determination of erythrocyte sodium and potassium: the reference range for apparently healthy adults.
Authors: Mayer K D , Starkey B J 
Published: January 2020

Abstract
Separated erythrocytes are washed repeatedly with iso-osmolar magnesium chloride solution, lysed by adding saponin, and sodium potassium measured in the diluted hemolysate by flame photometry. The coefficient of variation for the method was less than 4%. Reference intervals determined for a healthy population and hospitalized (elective surgery) patients without electrolyte disorders were 4.6-7.8 mmol/liter for erythrocyte sodium concentration and 94-110 mmol/liter for erythrocyte potassium concentration (2.5-97.5 percentiles).
Compensation by zinc chelation for fluorescent background in determining coproporphyrin and uroporphyrin in urine.
Authors: Lavallee D K , Norelius J T 
Published: January 2020

Abstract
An improved method for separation and fluorescent analysis of coproporphyrin and uroporphyrin in urine was presented by Sobel, Cano, and Thiers [Clin. Chem. 20, 1397 (1974)]. Accurate determination of porphyrin concentrations by this method is impeded by the fluorescent background in urine samples, which varies from one specimen to another. By use of a straightforward procedure, zinc may be incorporated into coproporphyrin and uroporphyrin. Measurement of the difference in the fluorescent emission intensity at 650 nm for the porphyrin solutions before and after zinc incorporation compensates for fluorescent background and gives a more accurate determination.
In vitro cholesterol esterification in human serum.
Authors: Yao J K , Dyck P J 
Published: January 2020

Abstract
We report a simple, convenient, and reproducible method, involving the use of radiolabeled cholesterol dispersed in Tween 20 as a tracer and endogenous lipoproteins as a substrate, for measuring the rate of serum cholesterol esterification in vitro. The reaction of lecithin acyltransferase (EC 2.3.1.43) was enhanced by the presence of Tween 20, which probably accelerates the exchange between radiolabeled cholesterol and endogenous lipoprotein cholesterol. In sera from 65 normal subjects, the in vitro cholesterol esterification rate was significantly correlated (r=0.47,P=0.001) with age. The mean rate of esterification of 31 subjects 30 years old or younger was significantly lower than that of 34 subjects 31 to 64 years of age. We found no significant difference in the rate of esterification between men and women. The rate of cholesterol esterification (nmol/ml per h) was significantly correlated with the concentration of endogenous free cholesterol in serum, but the fractional rate (the percentage of radiolabeled cholesterol esterified per hour) was inversely proportional to the endogenous free cholesterol. The fatty acid composition of the cholesteryl esters formed by the acyltransferase reaction may provide an index in recognizing some specific disorder.
Evaluation of serum triiodothyronine and adjusted triiodothyronine (free triiodothyronine index) in pregnancy.
Authors: Parslow M E , Oddie T H , Fisher D A 
Published: January 2020

Abstract
We measured serum thyroxine (free and total), triiodothyronine (free and total), thyroxine-binding globulin, and triiodothyronine uptake by talc in 97 normal men and 50 pregnant women. Mean serum thyroxine and triiodothyronine concentrations were higher in the pregnant subjects (104 vs. 78 mug/liter and 1.69 vs. 1.30 mug/liter) because of a higher mean thyroxine-binding globulin concentration (70 vs. 38 mg/liter). Mean triiodothyronine uptake by talc was lower in the pregnant subjects (0.82 vs. 1.03). Mean free thyroxine concentrations were similar in the two groups, but mean free triiodothyronine concentrations were 10% lower in the pregnant subjects. Triiodothyronine uptake by talc and the diayzable thyroxine and triiodothyronine fractions were highly correlated (r = 0.85 and r = 0.82, P less than 0.001). Calculated free thyroxine index and free triiodothyronine index values (hyroxine and triiodothyronine indirectly adjusted, using triiodothyronine talc uptake to compensate for differences in thyroxine-binding globulin concentration), were statistically similar (84 vs. 82 and 1.38 vs. 1.34) in pregnant and male subjects. The results indicate that the total triiodothyronine concentration can be normalized on the basis of the triiodothyronine uptake by talc to correct for variations in thyroxine-binding globulin concentration.
Lipoxygenic micromethod for specific determination of lipase activity in serum and duodenal fluid.
Authors: Proelss H F , Wright B W 
Published: January 2020

Abstract
We propose a rapid enzymatic micromethod for the specific determination of lipase (EC 3.1.1.3) activity in serum and duodenal fluid. Free linoleic acid produced during 10-min incubation of 10 mul of sample with 1 ml of substrate (trillinolein emulsion) at 30 degrees C is converted by lipoxygenase (EC 1.99.2.1), in a coupled reaction, to its hydroperoxide, which is measured photometrically after solubilizing the reaction mixture in ethanol. Lipase activity is calculated from the rate of hydroperoxide formation, with linoleic acid as primary standard. The velocity of the reaction is greatest at pH 8.8, 35-37 degrees C, and a deoxycholate concentration of 3.6 mmol/liter. The energy of activation is 6.7 kcal/mol. The differing "apparent" Km values obtained for lipase in undiluted serum (4 X 10(-5) mol/liter) and in albumin-based diluents (1 X 10(-5) mol/liter) indicate the presence of a competitive inhibitor in the serum matrix. We detected no lipase activity in urine. Results by the proposed method correlate well with those by a copper soap extraction method (r = 0.95), but values are significantly higher for pancreatitis patients' sera (slope 1.6). The linear dynamic range extends to 1000 U/liter. Hemolysis, lipemia, and hyperbilirubinemia do not interfere. The normal range is 40-60 U/liter. Lipase activity of pancreatitis patients generally exceed 1000 U/liter during the acute phase and 250 U/liter for as long as 10 days after it.
Hydrolysis of steroid glucuronides with beta-glucuronidase preparations from bovine liver, Helix pomatia, and E. coli.
Authors: Graef V , Furuya E , Nishikaze O 
Published: January 2020

Abstract
We determined the enzymic activity of beta-glucuronidase preparations from bovine liver, Helix pomatia, and Escherischia coli with steroid glucuronides and nonsteroid glucuronides as substrates. We also studied the effect of Na2SO4 on the enzymic hydrolysis of several substrates with the three preparations of beta-glucuronidase. Na2SO4 increases the rate of hydrolysis of all substrates with beta-glucuronidase from bovine liver. Hydrolysis of a steroid glucoronide with beta-glucuronidase from Helix pomatia and E. coli is inhibited by Na2SO4. None of the three enzyme preparations gives complete hydrolysis of urinary steroid conjugates, because urine contains inhibitors, which can be removed by absorption chromatography of the urine on a column of neutral polystyrene resin Amberlite XAD-2. But when Amberlite XAD-2 is not used, hydrolysis of urinary glucuronides of androsterone, etiocholanolone, pregnanediol, estriol, and 17-hydroxycorticosteroids proves that, given an incubation time of 24 h, the beta-glucuronidase preparation from bovine liver, in the presence of Na2SO4, is suited for determining all of the above steroids except esriol; the preparation from Helix pomatia is good for determining estriol and 17-hydroxycorticosteroids; the preparation from E. coli is good for determining androsterone, 17-hydroxycorticosteroids, and especially estriol, the glucuronide, of which is maximally hydrolyzed in 2 h.
Faster estimation of reserve bilirubin binding capacity of serum from the neonate by thin-layer chromatography on sephadex.
Authors: Trivin F , Odièvre M , Lemonnier A 
Published: January 2020

Abstract
Knowledge of the reserve bilirubin-binding capacity is useful in management of hyperbilirubinemia in the newborn. We describe thin-layer gel chromatography that permits measurement of this variable, with a 250-mul sample of serum, within 50 min. Single samples from four different infants can be analyzed on the same plate. The capacity of 40 sera from jaundiced and of 19 sera from nonjaundiced infants was measured. Results by thin-layer Sephadex gel chromatography and column Sephadex chromatography correlated well. Dithiothreitol, added to the standard bilirubin solution, protected bilirubin from oxidation for at least six days, which obviated the time consuming preparation of standard solution before such determination.
Evaluation of the Du Pont aca alpha-amylase procedure.
Authors: James G P , Passey R B , Fuller J B , Giles M L 
Published: January 2020

Abstract
The procedure used with the Du Pont aca for alpha-amylase (1,4,-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) was evaluated in our laboratory and compared with the Roche Diagnostics "Amylochrome" and Perkin-Elmer Coleman 91 amylase assays. The within-run coefficients of variation (CV) for samples of fresh normal sera were: aca 5.8% and 4.3% on two different lots of reagent, Amylochrome 7.4%, and Coleman 91 3.3%. In sera with abnormally high amylase activity, the respective CV's were: aca, 1.2% and 0.8%; Amylochrome, 2.0%; and Coleman 91, 2.8%. Day-to-day precision studies on fresh and lyophilized normal and abnormal sera gave CV's in the following ranges: aca, 1.8% to 6.7%; Amylochrome, 3.0% to 5.2%; and Coleman 91, 4.5% to 5.9%. Results by the aca procedure were linearly related to activity to about 10-fold the upper limit of normal amylase activity. For serum, correlations were: r = 0.977 for aca vs. Coleman 91 and r = 0.974 for aca vs. Amylochrome. For urine they were: r = 0.978 for aca vs. Coleman 91 and r = 0.975 for aca vs. Amylochrome. Mean recovery from 53 supplemented samples was 98%. Icterus, hemolysis, and lipemia did not interfere with method correlation of aca vs. Coleman 91 or Amylochrome.
Measurement of Procainamide and N-Acetylprocainamide in Serum by High-Performance Liquid Chromatography
Authors: Shukur Lillian R , Powers James L , Marques Roberto A , Winter Michael E , Sadèe W 
Published: January 2020

Abstract
We measured procainamide (I) and its metabolite, N¬acetylprocainamide (II), in human serum samples by sol¬vent extraction, high-performance liquid chromatography on a reverse phase column, and detection at 280 nm, with use of external standards. The method requires 0.2 ml of serum and is sensitive to 0.3 mg of I and 0.6 mg of II per liter of serum, with intra-assay standard deviations of 0.22 and 0.24 mg/liter, respectively, at 5 mg/liter (n = 10) and inter-assay standard deviations of 0.63 and 0.81 mg/liter, respectively, at 7.5 mg/liter (CV 8.4 and 10.5 % , respec¬tively, n = 20). Concentrations measured by high-perfor¬mance liquid chromatography and by an established flu¬orescence technique correlated well (r = 0.98 for I and 0.97 for II). No interfering substances were found in 20 randomly selected sera from patients receiving a large number of other drugs. Of the pure drug substances tested, only sulfathiazole interfered with the assay of II. The method is therefore suitable for routinely monitoring these compounds in serum in a clinical laboratory. The high concentrations of the metabolite in a significant number of patients demonstrate the need to consider it as well as the parent drug as guides in optimizing dosage regiments for I.
Determination of Nonsuppressible Insulin-Like Activity in Human Serum by a Sensitive Protein-Binding Assay
Authors: Zapf Juergen , Kaufmann Ueli , Eigenmann Eugen J , Froesch E Rudolf 
Published: January 2020

Abstract
We describe a sensitive protein-binding assay for non-suppressible insulin-like activity in human serum. It can detect as little as 0.2 microunits (corresponding to 0.5 ng) of the activity in 0.4 ml of the assay mixture. It is measured in a low-molecular-weight fraction (termed "biological material") obtained by chromatography of serum on Se¬phadex G-50 in 1 mol/liter acetic acid. This fraction has been shown earlier to contain nearly all this biologically active material that is present in serum. A partially purified carrier protein from human serum is used as the binding protein; different concentrations of a partially purified preparation of material with the activity serve as standards, which compete with 1251-labeled tracer for binding. Bio¬logical material dilutes more or less in parallel with the standard over a 10-fold concentration range. In the chro¬matographed serum fractions, displacing activity appears between 50 and 80% bed volume, with the peak at 60%, and coincides with the distribution and the peak of radio¬activity obtained by chromatography of tracer. A good correlation (γ = 0.88) is observed between the values determined for this activity in the rat fat-pad assay and the protein-binding assay, although the latter yields about twofold higher results (160 ± 37 milliunits/liter vs. 345 ± 65 milliunits/liter, mean values for 18 normal sera). Values determined in the protein-binding assay are decreased in hypopituitary patients (183 ± 27 milliunits/liter) and in¬creased in acromegalics (486 ± 88 milliunits/liter), in accord with the results of the bioassay (68 ± 21 milli-units/liter for hypopituitary patients, 293 ± 53 for acro¬megalics).
Determination of Serum Bilirubin Concentration during Phototherapy of Newborns and In Vitro: Results Compared by the Direct Spectrometric Method and the Diazo Method
Authors: Ebbesen Finn 
Published: January 2020

Abstract
During direct illumination of a serum bilirubin solution the bilirubin concentration decreased markedly, both as de-termined by the direct spectrometric method and (even more so) by the diazo method. In contrast, I found the same values for serum bilirubin concentrations as determined by these two methods for serum from untreated, "single light," and "double light" treated full-term infants with neonatal hyperbilirubinemia without blood type immuni¬zation. The same was true for untreated and "single light" treated premature infants with this disease. Furthermore, no difference was found in the above-mentioned rela¬tionship between "single light" treated infants with rhesus hemolytic disease, "double light" treated infants with the same disease, and untreated infants with neonatal hyp¬erbilirubinemia without immunization, all born at term. This is important, because the direct spectrometric method is simpler and requires less serum than does the diazo method
The Gallium Melting-Point Standard: Its Application and Evaluation for Temperature Measurements in the Clinical Laboratory
Authors: Bowers George N , Inman Stanford R 
Published: January 2020

Abstract
I discuss the traceability of calibration of electronic ther-mometers to thermometric constants of nature or to the National Bureau of Standards, from a manufacturer's basic standards through the manufacturing process to the user's laboratory. Useful electrical temperature sensors, their advantages, and means for resolving their disadvantages are described. I summarize our development of a cell for realizing the melting phase equilibrium of pure gallium (at 29.770 °C) as a thermometer calibration fixed point, and enumerate its advantages in the routine calibration veri-fication of electrical thermometers in the clinical chemistry laboratory.