bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous measurement of secondary and tertiary tricyclic antidepressants by GC/MS chemical ionization mass fragmentography.
Authors: Wilson J M , Williamson L J , Raisys V A 
Published: January 2020

Abstract
We present a method for measuring seven commonly used tricyclic antidepressants in plasma. This method is suitable for monitoring therapeutic concentrations and for screening drug overdoses in cases where the identity of the abused tricyclic antidepressant may not be known. Drugs from alkalinized plasma are extracted into hexane in one step; two injections into the gas chromatograph/mass spectrometer follow. The tertiary amines (amitriptyline, doxepin, and imipramine) are analyzed by direct injection; the secondary amines (nortriptyline, desmethyldoxepin, desipramine, and protriptyline) are analyzed after derivitization with trifluoroacetic anhydride. Clomipramine and desmethyltrimipramine are suitable internal standards. Chemical ionization mass fragmentography, with methane as the reactant gas, is used. While maintaining specificity for these drugs, concentrations in human plasma ranging from 5 to 500 microng/liter can be measured. The coefficients of variation are about 4 to 11%.
Gamma-glutamyltransferase activity in plasma: statistical distributions, individual variations, and reference intervals.
Authors: Schiele F , Guilmin A M , Detienne H , Siest G 
Published: January 2020

Abstract
Measurement of gamma-glutamyltransferase activity in plasma provides a useful index to liver function. Using as our study population those persons coming to the Center for Preventive Medicine, we described and measured the significance and importance of physiological and environmental variations. We established a classification for the variation factors. The three most important factors affecting this activity were drug intake, alcohol consumption, and excessive weight, followed by sex and age. We suggest a preliminary group of reference intervals for healthy subjects to be used in interpreting a laboratory test.
Determination of plasma glucose with use of a stirrer containing immobilized glucose dehydrogenase.
Authors: Kuan J W , Kuan S S , Guilbault G G 
Published: January 2020

Abstract
A stirrer containing immobilized glucose dehydrogenase has been successfully used for determining glucose in plasma. The device is usable for at least two months and for about 500 assays. The reaction was measured kinetically and linearity was observed to 4 g of glucose per liter. Tested with aqueous glucose and with deproteinized plasma, within-day and day-to-day precision were good. Interference and method-comparison (hexokinase method) were examined. The performance of this system makes the technique useful and attractive for routine use in small-volume clinical laboratories.
Determination of acetaminophen and phenacetin in plasma by high-pressure liquid chromatography.
Authors: Gotelli G R , Kabra P M , Marton L J 
Published: January 2020

Abstract
We describe a sensitive and precise high-pressure liquid chromatographic method in which acetoacetanilide is used as the internal standard to simultaneously determine acetaminophen and phenacetin in plasma. Therapeutic as well as toxic concentrations can be determined on as little as 0.1 ml of plasma. Sample preparation is rapid and chromatography is complete in 5 min. Quantitation is accurate at 0.5 mg/liter concentration for both drugs. Day-to-day precision within 5% is attainable. Of 36 other drugs tested, only theophylline interfered, with the determination of acetaminophen.
Effect of sodium sulfate on the hydrolysis of 17-hydroxycorticosteroid- and p-nitrophenyl-glucuronides with beta-glucuronidase preparations from bovine liver.
Authors: Furuya E 
Published: January 2020

Abstract
Previous papers dealt with the discovery that hydrolysis of 17-hydroxycorticosteroid glucuronides in urine with beta-glucuronidase preparations from bovine liver is increased by adding sodium sulfate to the incubation medium. Here, we conclude that sodium sulfate not only increases the activity of bovine liver beta-glucuronidase on 17-hydroxycorticosteroid glucuronides and p-nitrophenyl glucuronides, but also removes the inhibitory activity of substances of high molecular weight in urine and, moreover, inhibits urine putrefaction during the hydrolysis. The net effect is an increased yield of urinary 17-hydroxycorticosteroids. In the incubation with sodium sulfate (Na2SO4, final concentration 80 g/liter, 500 Fishman units of beta-glucuronidase per milliliter of urine, pH 5.0, 48 degrees C, 18 h) the analytical recovery of 17-hydroxycorticosteroid glucuronides added to 12 urine samples proved to be 98 +/- 1.8% (95-100).
Simultaneous determination of hemoglobin derivatives, oxygen content, oxygen capacity, and oxygen saturation in 10 microliters of whole blood.
Authors: Rossi-Bernardi L , Perella M , Luzzana M , Samaja M , Raffaele I 
Published: January 2020

Abstract
We describe a new method for simultaneous determination of four hemoglobin derivatives (deoxyhemoglobin, Hb; oxyhemoglobin, HbO2; methemoglobin, Hb+; and carbon monoxide hemoglobin, HbCO) and total oxygen content in 10 microliters of whole blood. Percentage HbO2, HbCO, Hb+, total hemoglobin (Hbt), and oxygen capacity can also be obtained from the experimental data by simple calculations. Total analysis time is 1 min. Blood is diluted 100-fold with a buffer contained in a quasi-anaerobic cuvette, where simultaneous measurements of oxygen pressure (by a po2 electrode) and adsorbance (at 497, 565, and 620 nm) are made. The decrease of oxygen pressure, as recorded by the oxygen electrode, is proportional to the amount of deoxyhemoglobin. The concentrations of HbO2, HbCO, and Hb+ can be obtained from absorbance measurements at the specified wavelengths. The new method eliminates the use of short-path optical cells and, due to the low sample volume requirement, makes possible the automated measurement of hemoglobin derivatives and oxygen saturation in arterialized capillary blood.
Quantitative analysis of biological marker synthesis in tumor cell cycle.
Authors: Woo K B , Enagonio R D 
Published: January 2020

Abstract
A quantitative relationship between tumor cell number and biologic marker concentration has been investigated and characterized by the previously developed discrete-time kinetic model for the study of cell kinetics. Here, this model is further expanded to cope with both cell cycle kinetics and biologic marker synthesis. A synchronized tumor-cell population is examined to determine the time course of the synthesis of markers in relation to cell cycle. The DNA content distributions, measured by flow microfluorometry, are analyzed by use of the model, and the cell age distribution is extracted. The average marker content per cell in cell cycle is measured for each time sequence in synchronized cell populations. The model, incorporating the cell age distribution and the average marker content per cell in cell cycle, enables one to generate the marker content distribution, from which the cell number is estimated from the marker concentration. The model performance is further evaluated with Chinese hamster ovary cells, and their polyamine content and the total polyamine concentration during synchronization is calculated and related to the total cell number.
Automated zone electrophoresis--experiments and new concepts.
Authors: Fosslien E 
Published: January 2020

Abstract
I have investigated various modalities of automation of zone electrophoresis. One system has already been previously described (U.S. Pat. No. 3,896,021). Other systems investigated can be divided into batch systems and one random-access system; the former involve separation on cellulose acetate that is supported on 0.127 mm thick polyester (Mylar) film in the form of tape, cards, or discs. Systems in which the separation is in a direction transverse to the long axis of the tape use a typical tape width of 7.5 cm; systems in which separation is longitudinal make use of supports of various widths, depending upon the assay rate desired. Concepts were also developed for a random-access systems for automated electrophoresis, which requires no start-up time. Small Lucite cassettes are used, one for each sample. Each cassette has one surface of either cellulose acetate or any of several gels used for electrophoretic separation. There are further small wells for sample and calibrator. The loaded cassette is inserted into an input queue that allows serial processing. The cassettes move sequentially through prewetting (if needed), sample application, electrophoretic separation, staining, and scanning. This system should also be suitable for automated isoelectric focusing.
Quantitative assays of enzyme activity in single cells: early prenatal diagnosis of genetic disorders.
Authors: Hösli P 
Published: January 2020

Abstract
The combined use of special cell culture techniques and biochemical ultramicromethods permits one to handle very small amounts of materials, to reduce the costs of chemicals, and more accurately to assess gene dosage effects by expressing enzyme activities per cell instead of per total cell protein. An alkaline phosphatase induction test has been developed which allows one to screen small numbers of fibroblasts for lysosomal storage diseases, cystic fibrosis, and chromosomal disorders. A successful attempt has been made to automate the microtechniques. Combining the alkaline phosphatase induction with the ultramicro automatization should eventually permit one to screen all pregnancies for major possible fetal genetic defects. Automated ultramicro enzyme assays should contribute to the general development of clinical chemistry.
Development of instrumentation and fluorochromes for automated multiparameter analysis of cells.
Authors: Leif R C , Thomas R A , Yopp T A , Watson B D , Guarino V R , Hindman D H , Lefkove N , Vallarino L M 
Published: January 2020

Abstract
We have developed and interfaced to a computer an automated instrument (the AMAC III) which is designed to observe simultaneously several physical parameters of cells. Typical parameters include electronic cell volume (Coulter effect), RF amplitude (opacity), multiwavelength fluorescence of cytological stains, and cell light-scattering. The use of a new ultraviolet laser combined with a holographic grating spectrograph promises to increase the number of fluorescing species that can be detected simultaneously. This number can be further increased by use of special rare-earth-based fluorochromes, that emit well-defined, spectrally distinct peaks.
Continuous-flow analysis for glucose, triglycerides, and ATP with immobilized enzymes in tubular form.
Authors: León L P , Sansur M , Snyder L R , Horvath C 
Published: January 2020

Abstract
Small-bore ("Autozyme") tubes with immobilized enzymes at the inner wall have been developed and studied for application in the Technicon "SMAC" high-speed continuous-flow biochemical analyzer. Tubes coated with glucose oxidase (D-glucose:oxygen oxidoreductase, EC 1.1.3.4) have been prepared for the assay of glucose, with colorimetric assay of the hydrogen peroxide produced; tubes coated with glycerol kinase (ATP:glycerol phosphotransferase, EC 2.7.1.30) for the enzymatic assay of triglycerides; tubes coated with hexokinase (ATP:D-hexose-6-phosphotransferase, EC 2.7.1.1) and glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate:NAD+ oxidoreductase EC 1.1.1.49) for the measurement of ATP, an intermediate product in assays for creatine kinase. With use of 10-15 cm lengths of Autozyme tube and SMAC hydraulics (150 samples per hour), assay sensitivity and carryover were similar to values for the corresponding free-enzyme methods. These immobilized enzymes were sufficiently stable for one to eight weeks of continuous use before replacemnt. We conclude that suitable bound-enzyme tubes can replace either single or multiple free-enzyme reagents in many continuous-flow assays at high sampling rates.
pH and the activity of porphobilinogen synthase in human blood.
Authors: Chiba M , Tashiro A , Kikuchi M 
Published: January 2020

Abstract
For determination of the activity of this enzyme (EC 4.2.1.24) in blood, pH dependency was evaluated by using whole blood and washed erythrocytes. The effects of assay methods, original and final pH, and use of sodium or potassium phosphate buffer were examined. The pattern of pH dependency differed for whole blood and washed erythrocytes, whether blood from normal or lead-exposed subjects was examined. The pH optimum for the activity in erythrocytes from lead-exposed subjects was the same as for the normal persons if the concentration of lead in blood did not exceed 80 microgram/100 g of whole blood. Hemolyzing blood by placing it on solid CO2 decreases the activity.
Calculation of radioimmunoassay standard curves.
Authors: Naus A J , Kuppens P S , Borst A 
Published: January 2020

Abstract
A method for calculating radioimmunoassay standard curves, based on the theory of Ekins et al., is described. Because a four-parameter model is used, nonlinear standard curves are the result. The calibration curve is fitted to the measured standard points by means of a weighted least-squares method. The program based on this model can be easily processed on a desk-top calculator. For all 250 runs of six different assays, very good standard curves could be obtained. The mean deviation between the concentrations of the standard points and the corresponding calculated values was about 6%. In 26% of the cases it could be shown that the model we describe gave significantly better results than did two simpler ones.
Detection of heterozygotes for phenylketonuria by constant intravenous infusion of L-phenylalanine.
Authors: Jagenburg R , Rödjer S 
Published: January 2020

Abstract
We measured the rate of elimination of phenylalanine by constant intravenous infusion of L-phenylalanine in 14 parents of children with phenylketonuria and in 21 subjects with a negative family history for this disease. When reciprocals of the observed elimination rates were plotted against the reciprocals of the increase in the plasma phenylalanine concentrations, approximately straight lines resulted. The theoretical maximum elimination rate, the mean value for which was 32 mmol/h in the reference subjects, was reduced by 41% in the phenylketonuric heterozygotes. The elimination rate at an increase in plasma phenylalanine concentration of 0.5 mmol/liter discriminated the phenylketonuric heterozygotes from normal homozygotes, with no overlap between the groups. A lower plasma tyrosine concentration in the phenylketonuric heterozygotes than in the reference subjects at the same rate of elimination of phenylalanine indicated an increased rate of elimination of tyrosine at a fixed concentration of this amino acid in these subjects.
Determination of free thyroxine in serum by radioimmunoassay.
Authors: Jiang N S , Tue K A 
Published: January 2020

Abstract
We describe a sensitive and specific radioimmunoassay for free thyroxine, directly determined in the diffusate obtained from equilibrium dialysis of serum. The intra- and interassay precisions were 7.5 +/- 0.27 and 9.1 +/- 0.58 ng/liter (mean +/- SD), respectively. The free thyroxine concentrations of normal persons and patients with thyroid disease were as follows: normal, 7.6 +/- 1.7; euthyroid patients receiving phenytoin, 6.9 +/- 1.4; hypothyroidism, 2.9 +/- 1.3; and hyperthyroidism, 32.3 +/- 12.3 ng/liter (mean +/- SD).
Determination of thyroxine-binding globulin in human serum by single radial immunodiffusion and radioimmunoassay.
Authors: Kågedal B , Källberg M 
Published: January 2020

Abstract
Two immunochemical methods for determination of thyroxine-binding globulin in human serum were developed, in which the purified globulin and monospecific antiserum to it are used. One method, based on radial immunodiffusion, has good precision and values for analytical recovery. Reference values obtained for men were 9.8-17.8 mg/liter and for women 11.3-20.5 mg/liter. The sex-related difference was significant. The other method is based on radioimmunoassay, with use of an iodinated acylating agent for the labeling of thyroxine-binding globulin. The relative merits of the two methods are discussed.
Ammonia production during clot retraction and its use in assay of fibrinoligase.
Authors: Mousli S , Wakid N W 
Published: January 2020

Abstract
Clotting of recalcified plasma is followed by an increase in its ammonia content that lasts 4 to 6 h. This ammonia production closely parallels the increase in acid-insoluble fibrin, which is evidence that the ammonia results from the action of fibrinoligase. If the clot is removed, ammonia production stops. The initial velocity of ammonia production is directly proportional to the fibrinogen concentration in plasma. Thus the rate-limiting factor in normal shed blood is the fibrinogen concentration. A maximum of 6.4 +/- 1.5 (SD) molecules of ammonia are produced per molecule of fibrinogen. Determination of the total ammonia produced is the fastest direct method of estimating the extent of frbrin cross-linkage in whole plasma. A method is proposed for assaying fibrinoligase, based on the rate of ammonia production in the presence of casein as substrate. Normal values are 7.6 +/- 2.9 (SD) mumol/min per liter of plasma.
Effect of washing procedures on trace-element content of hair.
Authors: Assarian G S , Oberleas D 
Published: January 2020

Abstract
A pooled sample of hair was divided and portions prepared for analysis by three washing procedures, to evaluate the effect of washing procedure on the subsequent trace-element (Zn, Cu, Mg) content. The methods selected were a detergent wash, a hexane-ethanol wash, and an acetone-ether-detergent wash. For all elements, there was a significant difference among the results after these wash procedures. Magnesium content of hair was most affected by washing, containing less than half of the magnesium of the unwashed hair. The detergent wash removed the most zinc and magnesium; the acetone-ether-detergent wash removed the most copper. Our results indicate that the trace-element analysis of hair is sensitive to the preparation technique and therefore is an unreliable source of information about trace-element status.
Measurement of serum and plasma ionic calcium with the "Space-Stat 20 Ionized Calcium Analyzer".
Authors: Husdan H , Leung M , Oreopoulos D , Rapoport A 
Published: January 2020

Abstract
Ca2+ was measured in sera and plasma from 36 normal subjects (18 men 23-57 years old, and 18 women 20-52 years old) with the Space-Stat 20 Ionized Calcium Analyzer. Within-day and between-day precision (CV) for commercial serum-based specimens varied from 0.64-0.96% and 1.1-3.8%, respectively, depending on their mean concentrations. Plasma and serum showed within-day CV's of 1.05 and 0.79%, respectively. The linear regression of serum Ca2+ (y) on plasma Ca2+ (x) was y = 0.63x + 0.45 mmol/litre with a highly significant (P less than 0.001) coefficient of correlation (r) of 0.69. An approximate 5% increase in the mean Ca2+ concentration in serum over that found in plasma is probably due to heparin complexing. No significant sex-related difference was observed for either serum or plasma. The mean Ca2+ concentration of 29 refrigerated specimens tended to decrease in seven days (by 2.3%, not statistically significant). The normal Ca2+ range in serum and plasma (n = 35) was 1.08-1.18 and 1.02-1.14 mmol/litre, respectively.
Simultaneous assay for vitamin B12 and folate compared with separate assay.
Authors: Whigham W R , Sudarsanan L 
Published: January 2020

Abstract
Radioligand methods are now well established for measurement of serum vitamin B12 and folate. Often these two assays are requested together. Thus a way of doing them simultaneously would save considerable time and expense. The objectives of this study were to determine the precision of a simultaneous assay and to compare it with previously established assays for these vitamins.
Automated enzymic measurement of total cholesterol in serum.
Authors: Rautela G S , Liedtke R J 
Published: January 2020

Abstract
We describe a completely automated enzymic system for measuring total cholesterol in serum. All reagents are contained in an analytical test pack and the test is performed on Du Pont's Automatic Clinical Analyzer (aca), which mixes the sample (20 microliter) and reagents and performs the necessary absorbance measurements and calculations. In the procedure, cholesterol oxidase oxidizes free cholesterol. The oxidation step produces cholest-4-en-3-one and hydrochloride peroxidesterase hydrolyzes cholesterol esters and cholesterol in direct proportion to the amount of cholesterol present. N,N-Diethylaniline hydrochloride and 4-aminoantipyrine react with the hydrogen peroxide to produce a quinoneimine dye (lambda max = 553 nm). Interacting reagents have been optimized simultaneously (coöptimization) utilizing response surface designs coupled with computer analysis of the data. Reagent efficiency is high and analytical performance reliable.
Direct analysis for cholesterol in gallstones by use of differential scanning calorimetry transition phase.
Authors: D'Ascenzo G , Cardarelli E , Magri A D , Bica T , Sabbatini M 
Published: January 2020

Abstract
A cholesterol transition phase at 37.5 degrees C has been shown by use of a Differential Scanning Calorimeter. The transition, reversible and reproducible, is useful for analytical purpose. We propose an analytical method for cholesterol in gallstones based on this transition. The method requires no intermediate reactions and cholesterol can be assayed directly in the powdered stone, with no other pretreatment or reagents. The analysis is highly specific, requires about 10 min, and is quite precise (CV about 1.5%) and accurate (about 2%).
Counterimmunoelectrophoresis in determination of prostatic acid phosphatase in human serum.
Authors: Foti A G , Cooper J F , Herschman H 
Published: January 2020

Abstract
We evaluated counterimmunoelectrophoresis for use in measuring prostatic acid phosphatase in detection of prostatic cancer. After staining for acid phosphatase, we could detect as little as 0.3 ng of purified enzyme standard complexed with antibody by this technique. However, when serum samples were used as antigen, the method was less sensitive (1.5-2.0 ng) because some of the serum proteins migrate with the phosphatase and decrease the intensity of the stain for acid phosphatase. For this reason we could not detect the phosphatase in serum samples of normal persons; only patients with moderately (or greater) increased activity in their serum showed positive results. In contrast, by radioimmunoassay as little as 1.0 ng of the phosphatase can be detected in serum.
Urinary free methyldopa determined by reversed-phase high-performance liquid chromatography.
Authors: Mell L D , Gustafson A B 
Published: January 2020

Abstract
We describe a chromatographic method, in which 3,4-dihydroxybenzylamine is used as the internal standard, for determining free methyldopa in human urine. The drug was adsorbed onto alumina, eluted, and the eluate directly injected onto a reversed-phase column (octadecyl-bonded silica stationary phase), with dilute acetate buffer (pH 2.7) as the mobile phase and ultraviolet detection at 280 nm facilitated. Methyldopa is well separated from other urinary biogenic amines present in the alumina extract, and other commonly used antihypertensives and diuretics do not interfere with the analysis. The sensitivity of the method is adequate to quantify 8.0 mg of methyldopa per liter in 30 ml of sample; the lower limit of detection is 25 ng. Analytical recovery for methyldopa varied from 95 to 102% with within-run and day-to-day coefficients of variation of 2.7 (n = 10) and 3.8% (n = 5), respectively. This procedure is readily adaptable for use in studies of the pharmacokinetics of methyldopa and to routine clinical laboratory use.