bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Five Methods for Determination of 2,3-Diphosphoglycerate in Blood
Authors: Teunissen A J , de Leeuw R J M , Boink A B T J , Hamelink M L , Maas A H J 
Published: January 2020

Abstract
Because the importance of 2,3-diphosphoglycerate in the regulation of the oxygen affinity of hemoglobin is recognized, there is growing need for a suitable method for determining this metabolite. Here we compare the colorimetric method of de Leeuw, two enzymatic rate-dependent methods (of Nygaard and Rörth and of Loos and Prins), and two enzymatic end-point methods (of Keitt and of Ericson and de Verdier). A good linearity was observed for all methods, up to 5.0 mmol of 2,3-diphosphoglycerate per liter of blood, except for the method of Ericson and de Verdier, for which an inexplicable upward drift in the calibration curve was found. Within-run precision in the duplicates and long-term precision in the methods of Loos and Prins and of de Leeuw were excellent. Mean analytical recoveries for all the methods ranged from 97 to 100%. In a paired comparison study of the methods, with the method of Loos and Prins as a reference, we did not find statistically significant differences. Coefficients of correlation were better than 0.990 (P &lt; 0.0005).
Use of the Simplex Method to Optimize Analytical Conditions in Clinical Chemistry
Authors: Krause Richard D , Lott John A 
Published: January 2020

Abstract
The optimum analytical conditions with regard to two or more variables can be determined in an unambiguous way by use of the simplex method. The method is particularly applicable to problems involving interacting variables. We describe the application of the simplex technique to the optimization of two procedures on a continuous-flow analyzer (AutoAnalyzer) and to the optimization of chemical variables in the lactate dehydrogenase-catalyzed pyruvate-to-lactate reaction and certain instrumental variables on a centrifugal analyzer (the ENI-GEMSAEC).
Mechanisms of the Liebermann-Burchard and Zak Color Reactions for Cholesterol
Authors: Burke R W , Diamondstone B I , Velapoldi R A , Menis O 
Published: January 2020

Abstract
Correlation of SO2 and Fe2+ measurements with new spectral data indicates that the Liebermann-Burchard (L-B) and Zak color reactions for cholesterol have similar oxidative mechanisms, each yielding, as oxidation products, a homologous series of conjugated cholestapolyenes. These studies further suggest that the colored species observed in these two systems are enylic carbonium ions formed by protonation of the parent polyenes. Thus, the red (λmax, 563 nm) product typically measured in the Zak reaction is evidently a cholestatetraenylic cation, and the blue-green product in the L-B reaction (λmax, near 620 nm) is evidently the pentaenylic cation. The effects of rate of carbonium ion formation and sulfuric acid concentration on sensitivity and color stability are discussed. A solvent extraction procedure is described for specifically converting cholesterol to 3,5-cholestadiene. Incorporating this step into the typical L-B method can increase the L-B sensitivity for cholesterol by several fold.
Spectral Interpretation and Kinetic Studies of the Fe3+-H2SO4 (Zak) Procedure for Determination of Cholesterol
Authors: Velapoldi R A , Diamondstone B I , Burke R W 
Published: January 2020

Abstract
Spectral changes and kinetic data presented for the Zak reaction show the pseudo-first-order character of the consecutive oxidative reactions undergone by cholesterol and selected steroid dienes. These data give excellent support to the proposed formation of the homologous series of steroidal enylic cations which are the absorbing species in the spectrophotometric cholesterol determination. Typical thermodynamic quantities of ΔG‡, ΔH‡, ΔS‡ and Ea are also reported for several different reactions. Low acetic-sulfuric acid ratios evidently result in the stabilization of the lower members of the homologous enylic series. Although excellent reproducibilities are obtained for premixed and non-premixed Zak reagents, it is necessary to use the premixed reagent if good temperature control is required, as would be the case for kinetic methods of analysis run under the conditions we used. The isosbestic point observed at 503 nm may also be used as an analytical wavelength because it is less sensitive to variables such as temperature, time, and steroid concentration.
Gas-Chromatographic Determination of Ethylene Glycol in Serum
Authors: Peterson R L , Rodgerson D O 
Published: January 2020

Abstract
We have developed a method for detection and quantitation of ethylene glycol in serum, based on the gas chromatography of its dibenzoate ester. No special reagents or equipment are required. The method is virtually free of interference and sensitive to less than 0.02 mg of ethylene glycol per milliliter. The total analysis time is about 90 min.
Refinement and Critical Evaluation of a Fluorometric Method for Measuring Leucine Aminopeptidase Activity in Serum or Tissues
Authors: Uete Tetsuo , Shimano Noriko , Shimizu Shuko 
Published: January 2020

Abstract
The fluorometric method for measuring leucine aminopeptidase (EC 3.4.11.1) activity in biological systems, with L-leucyl-β-naphthylamide as the substrate [Clin. Chem. 16, 412 (1970)] was critically evaluated and refined. In this enzyme assay system, a few precautions are necessary in determining β-naphthylamine liberated from the substrate by the enzyme action. In water, tris(hydroxymethyl) aminomethane buffer, and ethanol, β-naphthylamine, excited at 280 nm, fluoresces at 400 nm with a greater intensity than when an excitation wavelength of 340 nm is used. However, in the presence of protein or substrate the fluorescence intensity with an excitation wavelength of 280 nm is markedly diminished, and is less intense than that with 340 nm. Therefore, an excitation wavelength of 340 nm is preferred to 280 nm, to obtain increased sensitivity. Bilirubin and hemoglobin also slightly diminish the fluorescence intensity.
A Small Portable Centrifugal Fast Analyzer System
Authors: Scott Charles D , Burtis Carl A , Johnson Wayne F , Thacker Louis H , Tiffany Thomas O 
Published: January 2020

Abstract
The recent development of minature fast analyzer systems based on the GeMSAEC principle, coupled with the possibility of direct introduction of unprocessed liquid samples, has been further extended to include a very small analytical system that is inexpensive, battery-operated, and portable. The basic analyzer is included in and on a cabinet, about 10 x 10 x 10 cm, and a coupled data-processor records analytical data in absorbance units and in arbitrary fluorescence units. The system is compatible with up to seven simultaneous colorimetric or fluorometric assays on physiologic fluids. The dynamic mode of sample loading is used, and the system is compatible with the introduction of unprocessed whole blood. End-point or rate analysis is possible, and the coefficient of variation obtained in multichemistry tests on a single serum sample introduced dynamically is comparable to that obtained with larger Centrifugal Fast Analyzer systems.
Immobilized Glucose Oxidase Used to Measure Glucose in Serum
Authors: Kunz Hans J , Stastny Milos 
Published: January 2020

Abstract
We report an analytical system in which glucose oxidase immobilized on controlled-pore glass is used. The immobilized glucose oxidase was packed in a column that was part of a continuous-flow system. Oxygen depletion of the buffer was measured with a Clark-type electrode, and the resulting data were stored on tape and then evaluated with a PDP-12 computer. The relative advantages of several measurement approaches are given: (a) an endpoint method for prediluted sample, (b) an endpoint method for discrete, undiluted 9-µl samples, and (c) a maximum reaction rate measurement with discrete, undiluted samples. Catalase and mutarotase interferences were considered and found insignificant under the conditions chosen. The effects of protein, fluoride, and oxalate were determined. The column can be re-used for at least 1000 samples. Useful storage life of the immobilized glucose oxidase preparation, measured at intervals during a year, exceeded one year at room temperature.
Xanthine Oxidase Deficiency: Studies of a Previously Unreported Case
Authors: Holmes Edward W , Mason David H , Goldstein Leonard I , Blount Robert E , Kelley William N 
Published: January 2020

Abstract
Xanthinuria is a familial disorder of purine metabolism that results from a marked deficiency of xanthine oxidase (EC 1.2.3.2) activity. We report here the clinical and biochemical features of a new case of xanthinuria. Serum urate concentration was 0.8 mg/100 ml, urinary uric acid excretion was 16 mg per day, urinary oxypurine excretion was 1630 µmol per day, and total purine excretion was 314 mg per day. After allopurinol was administered, total purine excretion was 323 mg per day and erythrocyte phosphoribosylpyrophosphate content was unchanged. The ratio (by wt) of xanthine to hypoxanthine in the urine was 4.6 before and 9.6 after allopurinol was administered to this patient. Both allopurinol and oxipurinol were detectable in urine. Orotic acid and orotidine excretion increased from undetectable amounts (&lt;2 mg per day) to 47 and 86 mg per day, respectively. These data suggest that this xanthinuric subject has a markedly decreased xanthine oxidase activity, although some residual activity may be functional in vivo. It is probable that he re-utilizes purine so extensively that hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) is virtually saturated with hypoxanthine and xanthine in vivo. In addition, these data indicate that the increase in orotic acid and orotidine seen in normal and gouty subjects taking allopurinol is not a direct consequence of xanthine oxidase inhibition, but probably an effect of allopurinol or one of its metabolites on pyrimidine biosynthesis.
Automated Procedure for Determination of Sialic Acids and 2-Deoxyribose in Blood and Tissues
Authors: Engen R L , Anderson A , Rouze L L 
Published: January 2020

Abstract
A manual procedure for measuring sialic acids in blood and tissue and an automated procedure for measuring sialic acids in blood have been combined and modified so that sialic acid concentrations in both blood and tissue can be determined by continuous-flow analysis. Because 2-deoxyribose interferes with tissue sialic acid determinations, there must be a correction for color produced by it. In the calculation of sialic acids, the value for 2-deoxyribose can simultaneously be obtained. In addition to the analyses of mixed standards of sialic acids and 2-deoxyribose, we report analytical data for rat blood and tissue samples.
Manganese, Copper, and Zinc Concentrations in Serum and Packed Blood Cells during Acute Hepatitis, Chronic Hepatitis, and Posthepatitic Cirrhosis
Authors: Versieck Jacques , Barbier Fabrice , Speecke Albert , Hoste Julien 
Published: January 2020

Abstract
Manganese, copper, and zinc concentrations were determined in serum and packed blood cells of normal controls, patients with acute and chronic (persistent or aggressive) hepatitis, and cases of postnecrotic cirrhosis. During the active phase of acute hepatitis, serum manganese concentrations are invariably increased; the difference between the mean value and the normal is highly significant, P &lt; 0.001. The mean serum copper is also significantly increased (P &lt; 0.01). The concentrations become normal during the subsiding phase. In chronic aggressive hepatitis and posthepatitic cirrhosis, the mean serum manganese concentration is increased, P &lt; 0.001, whereas the serum zinc concentration is frequently decreased. There is a highly significant (P &lt; 0.001) positive correlation between serum manganese concentration and the activity in serum of aminotransferases, in subjects with acute or chronic hepatitis or postnecrotic cirrhosis.
Values for Urinary Excretion of D-Glucaric Acid by Normal Individuals
Authors: March James , Turner William J , Shanley Josette , Field John 
Published: January 2020

Abstract
The urinary excretion of D-glucaric acid reflects the activity of hepatic enzymes that hydroxylate and detoxify many substances foreign to the body. We measured it in 38 healthy unmedicated males (ages, 3 to 90 years; weights 11.8 to 136 kg) and in 15 females (ages, 10 to 80). The males, regardless of age or weight, excreted 56.1 ± 15.7 (SD) nmol of D-glucaric acid per milligram of creatinine. A "standard man" would excrete 98 µmol of this compound per day, in agreement with observations by other workers. We infer that the normal hydroxylating activity of the liver is a direct function of body cell mass.
One-Hour Radioimmunoassay of Serum Drug Concentrations, as Exemplified by Digoxin and Gentamicin
Authors: Berk Lee S , Lewis John L , Nelson Jerald C 
Published: January 2020

Abstract
Double-antibody radioimmunoassays in which tritium is used for labeling have been adapted for emergency determinations of serum drug concentrations. In the cases of digoxin and gentamicin, the first and second antibody incubations may be carried on simultaneously, minimizing incubation times (10 and 27 min, respectively). Counting the bound radioactivity in solubilized immunospecific precipitates decreases variability in the composition of the phase counted and markedly decreases problems of quenching and chemiluminescence. Logitlog transformation of the sigmoidal standard curve results in a straight line, which can be described by its slope and intercept and which remains constant if assay conditions and critical reagents are held constant. Because the slope and intercept of the standard curve are characteristic of a given assay system, it is possible to calculate the theoretical standard curve for a specific assay system by using the means of previously observed slopes and intercepts. Thus, a separate standard curve need not be prepared for each subsequent assay run. Total time required for drug determinations is now less than 1 h. When unknown samples were measured by both the conventional radioimmunoassay method and the new rapid radioimmunoassay method, the values correlated well (r = 0.99) for both digoxin and gentamicin.
Manual Immunonephelometric Assay of Proteins, with Use of Polymer Enhancement
Authors: Lizana Jorge , Hellsing Kristoffer 
Published: January 2020

Abstract
A manual immunonephelometric method for proteins has been developed by using an ordinary fluorometer as a nephelometer. By applying the enhancing effect of polyethylene glycol (av mol wt, 6000) on the immunological reaction, albumin and fibrinogen were quantitated after a 10-min reaction time. Under the present conditions the sensitivity was increased and thus antiserum consumption was decreased. The reaction conditions were carefully studied with respect to optimal time and concentration of the reactants. The precision of the method was 2.6-3.6% (CV). The lower detection limit in the albumin-antialbumin system was 0.1 mg/liter. Comparative studies showed a correlation coefficient of 0.991 with an automated immunonephelometric method for urinary albumin, and of 0.908 with a thrombin clottable method for plasma fibrinogen. We especially suggest use of this manual immunonephelometric method where small series of samples are to be analyzed.
Use of Control Sera for Monitoring Temperature Changes during pH and PCO2 Measurements
Authors: Manning John P , Sasaki Daniel N , Wertlake Paul T 
Published: January 2020

Abstract
We evaluated the temperature coefficients from 25 to 38 °C for aqueous calibration materials, serum (protein-based) control material, and patients’ samples in blood pH measurements and gas analysis. Whereas the aqueous buffers and calibration gases (used as unknowns) were not affected by changing temperature, the temperature coefficients of patients’ samples and protein-based control materials varied similarly to those reported in the literature: 0.011 and 0.014 vs. 0.015 pH/ °C, and 1.76 and 1.57 vs. 1.80 mm Hg/°C. We conclude that the periodic use of suitable control materials can assist in the detection of temperature abnormalities.
Automated Enzymatic Micromethod for Determination of Uric Acid in Serum and Urine with a Centrifugal Analyzer
Authors: Pesce Michael A , Bodourian Selma H , Nicholson John F 
Published: January 2020

Abstract
Uric acid is determined in serum and urine by an enzymatic method on a centrifugal analyzer. The sample (8 µl) is mixed with the enzyme uricase in a sodium borate buffer. The resulting decrease in absorbance at 292 nm is linearly proportional to the concentration of uric acid from 1 to 75 mg of uric acid per deciliter. Use of a centrifugal analyzer eliminates measurement of a separate serum blank. Recovery of uric acid added to serum and urine averaged 100% (range: 97-110%). Within-run precision (CV) on a serum pool for which the mean value was 5.96 mg/dl was 2.52%; day-to-day precision, measured on the same serum pool over a seven-day period, was 2.81% (mean: 6.05 mg/dl). Results obtained for serum with the uricase method on a centrifugal analyzer and with the uricase method on the Du Pont aca yielded a correlation coefficient of 0.99.
Quantitative Gas-Chromatographic Determination of Short-Chain Fatty Acids in Aqueous Samples
Authors: Collin Dennis P , McCormick Patrick G , Schmitt Milton G 
Published: January 2020

Abstract
We report the use of SP-1200 (Supelco Inc.) for quantitative gas-chromatographic determination of short-chain fatty acids (C2-C5) in stool water. The ratio of peak areas for these acids to that for 2-methylvaleric acid (internal standard) is linear for each acid from 60 to 1800 mg/liter. Lactic acid, occasionally present in stool in abnormally high amounts, is not detectable as the free acid on SP-1200, but is determined as its propyl ester on diethyleneglycolsuccinate.
Determination of L-Tyrosine as Tyramine in Urine
Authors: Tashian Richard E 
Published: January 2020

Abstract
A procedure for the determination of l-tyrosine in human urine is described. Tyrosine is converted to tyramine by treating it with the decarboxylase present in an acetone-powder preparation of S. faecalis. The tyramine is then separated from the urine and assayed by the nitrosonaphthol method. Examples of the application of this technic to human urine are presented.
On the Determination of "Pancreatitis Lipase" in serum
Authors: Henry Richard J , Sobel Charles , Berkman Sam 
Published: January 2020

Abstract
The specificity of the lipolytic activity occurring in sera from patients with acute pancreatitis for olive oil has been demonstrated. The "lipase" method proposed by Goldstein and co-workers, employing tributyrin as substrate, does not measure "pancreatitis lipase" "Pancreatitis lipase" differs from the enzymes present in pancreatic extracts so that, if the former is the subject of concern in experimental studies, sera from patients with pancreatitis must be used as the source of the enzyme.
Several variables involved in the use of olive oil as substrate have been examined, and the technic finally arrived at is essentially that proposed by Cherry and Crandall with the exception of the use of thymolphthalein as indicator in the titration. Normal values for this technic were determined.
Comparison of the Archibald-Kern and Stransky Colorimetric Procedure and the Praetorius Enzymatic Procedure for the Determination of Uric Acid
Authors: Alper Carl , Seitchik Joseph 
Published: January 2020

Abstract
The Archibald modification of the Kern and Stransky procedure for uric acid has been studied and its efficacy for routine use in clinical chemistry evaluated. Mean values and the range of values for men and women have been determined.
Micro Determination of Cholesterol by Use of 0.04 Ml. of Blood Serum
Authors: Galloway Leora S , Nielson Patricia W , Wilcox Ethelwyn B , Lantz Edith M 
Published: January 2020

Abstract
A micro method for cholesterol determination adapted from the macro method of Sperry and Webb is described with comparisons of results obtained by the two methods. In general, the two methods gave similar results for free and total cholesterol.
Urinary Sulfur Partition in Normal Men and in Cancer Patients
Authors: Papadopoulou Daphne B 
Published: January 2020

Abstract
1. The partition of inorganic and total sulfate and total and neutral sulfur has been estimated in 10 normal men and 27 cancer patients.
2. The excretion of inorganic and total sulfate was found to be decreased and the neutral sulfur fraction increased in cancer patients more than in the normal subjects.
3. From the data above, it is suggested that there may be a decrease in the rate of the intracellular oxidation substances in the body of cancer patients.
Human Serum Bilirubin
Authors: O'Hagan J E , Hamilton Teresa , Le Breton E G , Shaw A E 
Published: January 2020

Abstract
The technic of Powell (3) for the estimation of serum bilirubin has been modified by reading the optical density of the solutions shortly after mixing the reagents and using a standard based on a more appropriate solution of crystalline bilirubin in pigment-free serum.
Seven specimens of bilirubin were examined spectrophotometric-ally; the disproportionality of the millimolar extinction coefficients at 453 mµ for the free-bilirubin and at 532 mµ for, the azobilirubin complex indicated the presence of an unreactive yellow pigment.
The destructive effect of sunlight on solutions of biirubin, noted in the literature, was confirmed, hence all estimations were done without delay or exposure to light for any length of time. The results obtained on apparently healthy blood donors, to detect possible carriers of homologous serum hepatitis, revealed no definite correlation between previous history of jaundice and increased serum bilirubin values, but as a precautionary measure individuals with values above 1.5 mg. per 100 ml. were not accepted as donors.
When 200 random values were plotted, the distribution curves gave a mean value higher for males than females. Furthermore, 108 donors (among the 25,000 screened) had biirubin values greater than 1.5 mg. per 100 ml. The eleven females of the group did not maintain high values, while 30 males recorded high values on more than one occasion, some consistently.
No significant correlation was found between high bilirubin values and a previous history of jaundice, nor were any cases of posttrans-fusion hepatitis traced to these donors. Somewhat arbitrarily, 1.5 mg. per 100 ml. was chosen as the upper limit of normal.
Practical Evaluation of Acid-Base Balance
Authors: Jacobi Herbert P , Barak Anthony J , Beber Meyer 
Published: January 2020

Abstract
The Co2 combining power bears a variable relationship to the in vivo plasma bicarbonate concentration, depending upon the type and severity of acid-base distortion. In respiratory alkalosis and metabolic acidosis the Co2 combining power will usually be greater than the in vivo plasma bicarbonate concentration; whereas, in respiratory acidosis and metabolic alkalosis the Co2 combining power will usually be less. Co2 content, on the other hand, will always parallel the in vivo plasma bicarbonate concentration quite closely, being only slightly greater. These facts, together with other considerations which are discussed, recommend the abandonment of the determination of CO2 combining power.
Improved Method for the Colorimetric Determination of Glutamic-Oxalacetic Transaminase Activity
Authors: Humoller Fred L , Holthaus Joseph M , Walsh John R 
Published: January 2020

Abstract
A modification of the Cabaud et at. method (1) for the determination of SGOT activity is described. The proposed modification consists of the elimination of the interference of unreacted DNPH by extracting the pyruvate dinitrophenyihydrazone with aqueous bicarbonate. The proposed method also employs a lower concentration of alpha-ketoglutarate, thus reducing its competition for the available DNPH.