bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative gas-chromatographic flame-ionization method for p-chlorophenoxyisobutyric acid in human serum and saliva.
Authors: Connor J N , Johnson G F , Solomon H M 
Published: January 2020

Abstract
We describe a gas-chromatographic method for p-chlorophenoxyisobutyric acid (I) the active metabolite of clofibrate. The drug and internal standards are separated from either serum or saliva by a double extraction procedure and converted to the corresponding butyl esters by reaction with iodobutane in a mixture of methanol and N,N-di-methylacetamide containing tetramethylammonium hydroxide. Within-run CV of this assay at a serum I concentration of 79.2 mg/liter was 2.3% and at a salivary I concentration of 2.5 mg/liter was 2.1%. Precision during four months of the serum and salivary assays at these concentrations was 4.1% and 6.2%, respectively. The mean serum concentration of I (12 h after dose) in patients receiving the drug at an average dose of 28.0 mg/kg per day was 109.6 mg/liter. Serum and salivary concentrations of I as determined by our procedure were used to calculate the unbound fraction of drug in human serum. Such measurements can be used to monitor therapy in patients with renal disease, where drug toxicity may arise from high concentrations of unbound I.
Simplified fluorometric assay for diphenylhydantoin in plasma.
Authors: Dill W A , Leung A , Kinkel A W , Glazko A J 
Published: January 2020

Abstract
The fluorometric benzophenone procedure for diphenylhydantoin has been simplified by eliminating the need for preliminary extraction of plasma with an organic solvent. Assays are done directly on 0.2 ml of plasma by treating it with alkaline permanganate to form benzophenone, extracting the benzophenone with heptane, and then shaking the heptane layer with sulfuric acid and measuring the fluorescence of the acid layer. The assay is highly reproducible, and adequately sensitive to detect 1 mug of the drug per milliliter of plasma. Fluorometric and gas-liquid chromatographic assays of 154 plasmas gave results that were not significantly different, even in the presence of phenobarbital, other barbiturates and anticonvulsant drugs, or of various tranquilizers and other commonly used drugs. The assay is rapid, the unit cost per assay low.
Beta-carotene content of certain organs from two patients receiving high doses of beta-carotene.
Authors: Mathews-Roth M M , Abraham A A , Gabuzda T G 
Published: January 2020

Abstract
We measured carotene in the livers of two patients receiving beta-carotene therapy for photosensitivity. In both patients, the amount of carotene was within reported ranges for patients on normal diets; no abnormal amounts of beta-carotene had accumulated in the livers after oral administration of large amounts of beta-carotene. Light-microscopic examination of the liver (specimen obtained at cholecystectomy) of one patient with erythropoietic protoporphyria and cholesterosis showed findings characteristic of these conditions. Electron-microscopically, semicrystalline inclusions were seen in the mitochondria of the hepatocytes; such inclusions have been reported in several conditions, including erythropoietic protoporphyria and porphyria cutanea tarda, and in control subjects. Microscopic examination of the liver of the other patient, who had Rothmund-Rhomson syndrome and died of acute bacterial meningitis, revealed no abnormalities. The cerebrum of the latter patient contained 13 mug of carotene per kilogram (wet weight) of brain. No previous report of analysis of human brain for carotenoids could be found.
Studies of the reliability of constituent target values established in a large inter-laboratory survey.
Authors: Grannis G F 
Published: January 2020

Abstract
Lyophilized serum specimens were manufactured in such a way that fixed quantitative interspecimen relationships were established. The specimens were analyzed for about twenty constituents by several thousand laboratories in 1971, 1972, and 1973. Most of the consensus mean values derived from these analyses were found to relect accurately the relationships established in the manufacture of the specimens. In addition, analyses of some of the specimens for calcium by the National Bureau of Standards confirmed the relationships. I conclude that the consensus mean values derived for most constituents are reproducible and any biases that may be present are consistent from survey to survey.
Ultramicro gas-chromatographic analysis for anticonvulsants, with use of a nitrogen-selective detector.
Authors: Vandemark F L , Adams R F 
Published: January 2020

Abstract
We describe a procedure for determining phenobarbital, primidone, and diphenylhydantoin simultaneously in 50-mul volumes of serum by use of gas chromatography and a detector with heightened sensitivity and selectivity for nitrogenous compounds. The drugs, together with an internal standard, 5-allyl-5-phenyl barbituric acid, are extracted from serum by the procedure of MacGee [Anal. Chem. 42, 421 (1970)]. The drugs are converted to their methyl derivatives by a modification of the procedure of Greeley [Clin. Chem. 20, 192 (1974)] and then analyzed on a column containing 3% OV-1, with a temperature program, and detected by a nitrogen-selective detector. The method is reproducible to about 7%. Sensitivities of 0.5 mg/liter for 50-mul serum samples are attained routinely. Mephobarbital interferes with the analysis because methylation yields the same product as methylated phenobarbital. Total analysis time for a single sample is 15 min.
Determination of erythrocyte folate by competitive protein binding assay preceded by extraction.
Authors: Mortensen E 
Published: January 2020

Abstract
Determination of the concentration of erythrocyte folate by means of competitive protein binding assay critically depends on the extraction procedure applied. Results will be influenced by variable factors such as the in vitro age of the blood samples, the degree of hemolysis, the presence of ascorbic acid, and the pH during extraction and elimination of proteins. The radioassay is strongly influenced by the pH of the final reaction mixture, the method used to separate free and protein-bound molecules, and the molecular configuration of the folates present. Based on experimental results presented, I describe a method for the determination of erythrocyte folate.
X-Prolyl dipeptidyl-aminopeptidase activity, with X-proline p-nitroanilides as substrates, in normal and pathological human sera.
Authors: Hino M , Fuyamada H , Hayakawa T , Nagatsu T , Oya H 
Published: January 2020

Abstract
X-Prolyl dipeptidyl-aminopeptidase (no EC no. assigned) activity in normal and pathological human sera was assayed with several newly synthesized X-proline p-nitroanilides as chromogenic substrates. Normal values for 88 healthy subjects (15 to 81 years old), with glycylproline p-nitroanilide as substrate at pH 8.7, were 54.9 +/- 1.5 (SE) (range, 25.7 - 96.0) mumol/min per liter of serum at 37 degrees C. The results suggest that the enzyme activities with all X-proline p-nitroanilides were increased in patients with hepatitis and decreased in patients with gastric cancer. On Sephadex G-200 column chromatography, normal human sera showed a single peak of enzyme activity with glycylproline p-nitroanilide as the substrate, which coincided with the peak with glycylproline beta-naphthylamide but was different from the peaks with leucine beta-naphthylamide. Sera from patients with hepatitis or liver cirrhosis showed an increase in the normal peak and the appearance of another new peak with glycylproline p-nitroanilide as substrate.
Urinary organic acids in man. I. Normal patterns.
Authors: Lawson A M , Chalmers R A , Watts R W 
Published: January 2020

Abstract
We studied qualitative pattern of urinary acidic metabolites excreted by normal persons. The results provide a basis on which to compare results for patients with potentially abnormal organic acidurias. A series of urinary polyhydroxy (aldonic and deoxyaldonic) acids has been identified. Most of these compounds have not been previously reported in human urine, except in connection with the present work, and are additional to the previously recognized urinary organic acids, which were also observed. Possible metabolic origins of some of the acids are briefly discussed.
Urinary organic acids in man. II. Effects of individual variation and diet on the urinary excretion of acidic metabolites.
Authors: Chalmers R A , Healy M J , Lawson A M , Watts R W 
Published: January 2020

Abstract
We have assessed individual variations in urinary acidic metabolite excretion and the effects of extreme alterations in dietary composition on these metabolites in selected normal persons who we considered representative of the general ambulant normal population. Extreme dietary alterations produced relatively small changes in the patterns or amounts of metabolite excretion, but large individual within-subject variations were observed. Our results indicate that variation in the ranges of excretion for the normal population mainly depend on individual metabolic variations rather than on dietary factors, and provide a basis for the assessment of the normal ranges determined from population surveys. Our results are discussed in relation to previous studies on the variability of urinary acidic metabolite excretion in man.
Analysis of whole blood by neutron activation: a search for a biochemical indicator of neoplasia.
Authors: Zdankiewicz D D , Fasching J L 
Published: January 2020

Abstract
We determined a total of 13 elements in the whole blood of cancer patients and controls by using instrumental neutron activation analysis. The samples were spotted as whole blood on small filter paper disks, allowed to dry at room temperature, and sealed between two polyethylene disks. They were then irradiated and counted. Eleven elements were determined by this method. Sodium and chlorine were measured by irradiating whole blood in polyethylene vials. Statistical analysis of the data predicts that, with a very hgih probability, cobalt and iron are lower, adn sodium, tantalum, lanthanum and chlorine are higher in the cancer patients than in the normal persons tested. Chromium, zinc, and bromine also show differences between the two groups at a probability exceeding 0.95. Variations are indicated in scandium and cesium also, but are less strongly supported. Hafnium and selenium show no significant differences.
Competitive enzyme-liked immunoassay with use of soluble enzyme/antibody immune complexes for labeling. I. Measurement of human choriogonadotropin.
Authors: Yorde D E , Sasse E A , Wang T Y , Hussa R O , Garancis J C 
Published: January 2020

Abstract
We described the principle of a new enzyme-immunoassay, competitive enzyme-liked immunoassay (CELIA), for quantitative measurement of soluble antigens and haptens. In the assay, binding of antibody to antigen-immunosorbent is competitively inhibited by the free antigen to be measured. The amount of first antibody bound to the immunosorbent is measured by an enzymatic technique in which a heterologous bridging antibody and a soluble antibody/enzyme immune complex are applied in sequence. The soluble complex we used was rabbit antiperoxidase/horseradish peroxidase. Peroxidase activity is inversely proportional to the concentration in the original sample of the substance to be assayed. The enzyme-linked reagents are potentially widely applicable to any substance to be measured. To demonstrate the feasibility of CELIA, we report a preliminary study of its application to the measurement of human chloriogonadotropin in serum and urine. The assay described for this hormone has a working range of 1 to 50 int. units per milliliter of sample. The technique obviates the disadvantages associated with measurement and handling of radioisotopes in radioimmunoassays and the only major instrumentation required is a centrifuge and a conventional spectrophotometer.
Modified nucleosides in urine: selective removal and analysis.
Authors: Uziel M , Smith L H , Taylor S A 
Published: January 2020

Abstract
Because excretion of certain nucleosides increases in all types of cancer, detection and treatment of the disease would be enhanced by rapid, simple quantitation of such nucleotides. To facilitate these analyses in urine, we have prepared a specific adsorbent for nucleosides. The affinity adsorbent gel contains an immobilized phenylboronic acid group that specifically binds cis-diols, as in ribonucleosides, which can then be quantititatively recovered by elution with acetic acid. The advantage of this boronate gel over other preparations lies in its high capacity in the swollen state (0.26 mmol/ml), so that only small volumes (less than 1 ml) of gel are required for assays. Nucelosides containing a free diol group on the ribosyl group are retained at pH 8.8 in 0.25 mol/liter salt solution with a retention volume of 15 or larger, as compared with values of 1 to 2 for the free bases. Negatively charged species (not including the boronate complex) are eluted earlier than neutral or cationic species. Added nucleosides (neutral, cationic, or anionic) are quantitatively recovered. Because pseudouridine is eluted in a unique position, this property has been used to measure it in urine. The procedures used are chemically mild. For example, we have confirmed the observation of Fink and Adams [Arch. Biochem. Biophys. 126, 27 (1968)] that urine contains N1-methyladenosine and not N6-methyladenosine, the alkaline rearranged product.
Erythrocyte porphobilinogen synthase (delta-aminolaevulinate dehydratase) activity: a reliable and quantitative indicator of lead exposure in humans.
Authors: Mitchell R A , Drake J E , Wittlin L A , Rejent T A 
Published: January 2020

Abstract
We assessed optimal conditions for assay of porphobillinogen synthase (EC 4.2.1.24) activity in human blood containing abnormally high concentrations of lead. Zn2+and -SH, both required for complete activation of the enzyme, had additive effects. Using a modified method based on these studies, we found blood lead concentration to be strictly proportional to ln(activated/nonactivated) enzyme activity. One brand of commercially available "lead-free" tubes contained a substance that interfered with this relationship. In vitro studies, with the modified assay, showed ALAD to be activated by low concentrations but inactivated by high concentrations of Hg2+, Cd2+, and ethylenediaminetetraacetate. We fouund no genetically influenced differences among unexposed individuals when in(activated/nonactivated) enzyme activities were compared. The technique is suitable for use in screening for lead poisoning in humans.
New approach to determination of total ketone bodies in serum.
Authors: Siegel L , Robin N I , McDonald L J 
Published: January 2020

Abstract
We describe a one-step assay for total ketone bodies in serum. D-BETA-Hydroxybutyrate is enzymatically oxidized by NAD+ to acetoacetate. This thermodynamically unfavorable reaction is driven to completion by coupling it with the enzymatic reduction of pyruvate by NADH. The acetoacetate so formed, as well as the pre-existing acetoacetate, is quantitatively decarboxylated to acetone in a gas chromatograph and measured directly. Thus by a single measurement for acetone, all three ketone bodies are simultaneously determined. In light of the ubiquity of situations associated with augmented ketone body production, the clinical implications of this approach are extensive.
Performance characteristics of rules for internal quality control: probabilities for false rejection and error detection.
Authors: Westgard J O , Groth T , Aronsson T , Falk H , de Verdier C H 
Published: January 2020

Abstract
When assessing the performance of an internal quality control system, it is useful to determine the probability for false rejections (pfr) and the probability for error detection (ped). These performance characteristics are estimated here by use of a computer stimulation procedure. The control rules studied include those commonly employed with Shewhart-type control charts, a cumulative sum rule, and rules applicable when a series of control measurements are treated as a single control observation. The error situations studied include an increase in random error, a systematic shift, a systematic drift, and mixtures of these. The probability for error detection is very dependent on the number of control observations and the choice of control rules. No one rule is best for detecting all errors, thus combinations of rules are desirable. Some appropriate combinations are suggested and their performance characteristics are presented.
Combined Shewhart-cusum control chart for improved quality control in clinical chemistry.
Authors: Westgard J O , Groth T , Aronsson T , de Verdier C H 
Published: January 2020

Abstract
We describe the adaptation of the decision limit cumulative sum method (cusum) to internal quality control in clinical chemistry. With the decision limit method, the cusum is interpreted against a numerical limit, rather than by use of a V-mask. The method can be readily implemented in computerized quality-control systems or manually on controls charts. We emphasize the manual application here and demonstrate how the technique can be implemented on existing Shewhart or Levey-Jennings control charts. This permits both cusum and Shewhart control rules to be used simultaneously on a single control chart and also minimizes the data calculations necessary for the cusum method. Computer simulation studies are used to determine the performance characteristics of several different cusum rules, alone and in combination with a Shewhart rule. These studies indicate that improvements in existing quality-control systems should be possible by addition of this simple cusum method and by use of a combined Shewhart-cusum control chart. This should be particularly advantageous when introducing the cusum method in laboratories with manual quality-control systems.
Presence of creatine kinase BB isoenzyme in some patients with prostatic carcinoma.
Authors: Feld R D , Witte D L 
Published: January 2020

Abstract
We have observed creatine kinase isoenzyme BB in the sera of nine of 19 patients with Stage D carcinoma of the prostate. Its presence does not seem to correlate with acid phosphatase activity in serum or the presence of bone metastases as indicated by increased alkaline phosphatase activity in serum. Only three of the nine patients with BB isoenzyme activity detectable in their serum had abnormal values for total creatine kinase activity, but all had abnormal values for alkaline and acid phosphatase activity. All 10 patients with no BB isoenzyme detectable had abnormal acid phosphatase values; however, only seven had increased alkaline phosphatase values and only one had increased creatine kinase activity.
High-performance liquid-chromatographic analysis for tryptophan in serum.
Authors: Krstulovic A M , Brown P R , Rosie D M , Champlin P B 
Published: January 2020

Abstract
Concentrations of total tryptophan were determined rapidly and sensitively in 50 microliter of serum by a reversed-phase partition version of high-performance liquid chromatography. For determination of total tryptophan, sample preparation requires only precipitation of the serum protein with trichloroacetic acid and removing excess trichloroacetic acid with a 1,1,2-trichlorotrifluoroethane(Freon)/tri-N-octylamine solution. Tryptophan in serum samples was detected by ultraviolet and fluorescence spectrometry. No interferences from the naturally occurring constituents of serum were observed. Elution time for tryptophan is 15 min, the limit of detection is 1 pmol.
Radioimmunoassay of parathyroid hormone (parathyrin) in monkey and man.
Authors: Hargis G K , Williams G A , Reynolds W A , Kawahara W , Jackson B , Bowser E N , Pitkin R M 
Published: January 2020

Abstract
A radioimmunoassay for rhesus monkey and human immunoreactive parathyrin was developed in which a selected anti-bovine parathyrin antiserum, radioiodinated purified bovine parathyrin tracer, and human parathyroid tissue-culture media standards were used. The resulting data indicate that (a) the method is sensitive, specific, accurate and reproducible; (b) it is valid for both the rhesus monkey and the human; (c) the serum immunoreactive parathyrin concentration of the monkey is essentially the same as that in man; (d) monkey immunoreactive parathyrin responds to changes in serum calcium concentration similarly to that in man; and (e) the rhesus monkey is therefore a suitable species in which to study parathyroid physiology, from which conclusions can be applied to the human.
New micromethod for measuring cholesterol in plasma lipoprotein fractions.
Authors: Bronzert T J , Brewer H B 
Published: January 2020

Abstract
A method is described for the reliable, fast, and relatively inexpensive fractionation of plasma lipoproteins and quantitation of their cholesterol content. This procedure requires 350 microliter of plasma and can be completed within 3 h. Plasma lipoproteins (175 microliter of plasma) were prestained with Fat Red 7B and centrifuged (Beckman Airfuge) at plasma density (d = 1.006 kg/liter) and at a solvent density of 1.060 kg/liter, adjusted by adding solid KBr. Prestained centrifuged samples demonstrated the characteristic elevation of chylomicrons in phenotypes I and V, low-density lipoproteins of phenotype II, very-low-density lipoproteins in phenotype IV and V, and continuum of pink color throughout the centrifuge tube, diagnostic of the floating beta lipoprotein of type III. Centrifuged samples were separated into top and bottom fractions by aspiration. Cholesterol was quantitated with an enzymic oxygen-electrode analyzer (Beckman Cholesterol Analyzer). Correlation coefficients between cholesterol values for plasma from normal hyperlipidemic individuals obtained with the Beckman Analyzer vs. the Technicon AutoAnalyzer II and SMAC systems were 0.977 and 0.973, respectively.
Hemoglobin interference with Du Pont Automatic Clinical Analyzer procedure for calcium.
Authors: Porter W H , Carroll J R , Roberts R E 
Published: January 2020

Abstract
Hemoglobin in concentrations of approximately 2.5 g/liter or greater significantly increases values for apparent calcium in serum as determined with the Du Pont aca, an interference attributable to the 575-nm absorption band of oxyhemoglobin being uncompensated by the 577--600 nm differential absorption reading of the calcium o-cresolphthalein complexone complex.
High-performance liquid-chromatographic assay for nitrofurantoin in plasma and urine.
Authors: Aufrère M B , Hoener B , Vore M E 
Published: January 2020

Abstract
The high-performance liquid-chromatographic method described here for the quantitative analysis for nitrofurantoin in urine and plasma involves direct analysis of urine samples and analysis of plasma samples after protein precipitation by methanol. The assay, which requires only 0.2 ml of biological fluid and shows a linear relationship in the range 0.02 to 200 mg/liter, can be performed in 9 min and is reproducible (CV less than 2%). Results for nitrofurantoin so obtained correlate well with those obtained by the Hyamine 10-X spectrophotometric method (CV = 2%), but the present method is more sensitive. With no modification, the present procedure can also be used for nitrofurazone. The sensitivity, accuracy, and convenience of the method make it suitable for clinical monitoring and pharmacokinetic/bioavailability studies with 5-nitrofuran derivatives.