bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comprehensive classification of kinetic methods of analysis used in clinical chemistry.
Authors: Pardue H L 
Published: January 2020

Abstract
This paper presents a comprehensive classification of kinetic methods of analysis used in clinical chemistry. Objectives of the presentation are to place kinetic methods into perspective with other analytical appraoches, to identify concisely what is and is not a kinetic method, to group different kinetic methods into categories that identify important differences in operational and performance characteristics, and to suggest terminology that can identify the different approaches without ambiguity. In addition to these major objectives, the paper includes a brief historical development of the kinetic approach that covers the period from 1881 to the present, and discusses some current terminology that is believed to be ambiguous and misleading. I suggest that the detection step in analytical methods can be divided into two general categories, called equilibrium and kinetic methods. The kinetic methods are then subdivided into two general categories called fixed sensor-signal and variable sensor-signal methods. Each of these groups is then subdivided into one-point, two-point, and multi-point methods, which are then further subdivided according to what types of blanks are used, what variables are measured, and how the measured data are used to compute enzyme activity or analyte concentration. The paper identifies some commercial instruments that represent different approaches and briefly discusses relative merits of different approaches.
Mechanisms of cellular enzyme release. I. Alteration in membrane fluidity and permeability.
Authors: Verrill H L , Pickard N A , Gruemer H D 
Published: January 2020

Abstract
Above-normal plasma enzyme activities resulting from increased release of intracellular macromolecules are an important diagnostic feature of Duchenne muscular dystrophy. These and other biochemical and histological characteristics of this disease are faithfully duplicated when imipramine and serotonin are administered to the rat. Imipramine, but not serotonin alone, causes release of enzymes from rat diaphragms and human lymphocytes and release of hemoglobin from erythrocytes in vitro. Ouabain causes neither. Imipramine-induced enzyme release is decreased by adding ATP to the specimen in vitro or in hypertonic solution. Imipramine inhibits the capping phenomenon (an aggregation of antigen/antibody complexes of the membrane) of human B lymphocytes labeled with fluorescein-conjugated antihuman immunoglobulins. Serotonin alone has no such effect, but, administered together with imipramine, it potentiates the inhibition of capping by imipramine.
Criteria for establishing a standardized method for determining alkaline phosphatase activity in human serum.
Authors: Bretaudière J P , Vassault A , Amsellem L , Pourci M L , Thieu-Phung H , Bailly M 
Published: January 2020

Abstract
We investigated factors influencing alkaline phosphatase activity in the course of developing criteria for the establishment of a standardized method for its determination in human serum at 30 degrees C. The effects of pH, phosphorylatable acceptor (2-amino-2-methyl-1-propanol and diethanolamine), 4-nitrophenyl phosphate, magnesium ion, zinc ion, temperature, volume fraction of specimen, and details of initiation of the reaction have been studied, with use of partly purified enzymes from bone, intestine, liver, and placenta, and sera from patients with a predominant characterized isoenzyme. The purity of the diethanolamine was examined and contaminant monoethanolamine was characterized as a competitive inhibitor. Two sets of recommended conditions are: 2-amino-2-methyl-1-propanol, 0.9 mol/liter; 4-nitrophenyl phosphate, 16 mmol/liter; magnesium ion, 1 mmol/liter; volume fraction of specimen 1/30, and pH30 degrees C 10.5; diethanolamine, 1.8 mol/liter; 4-nitrophenyl phosphate, 18 mmol/liter; magnesium ion, 1 mmol/liter; volume fraction of specimen 1/60, and pH30 degrees C 10.1. Serum is preincubated with all reagents but 4-nitrophenyl phosphate, which is used as the reaction-initiating substrate.
4-Nitrophenol in 4-nitrophenyl phosphate, a substrate for alkaline phosphatase, as measured by paired-ion high-performance liquid chromatography.
Authors: Culbreth P H , Duncan I W , Burtis C A 
Published: January 2020

Abstract
We used paired-ion high-performance liquid chromatography to determine the 4-nitrophenol content of 4-nitrophenyl phosphate, a substrate for alkaline phosphatase analysis. This was done on a reversed-phase column with a mobile phase of methanol/water, 45/55 by vol, containing 3 ml of tetrabutylammonium phosphate reagent per 200 ml of solvent. At a flow rate of 1 ml/min, 4-nitrophenol was eluted at 9 min and monitored at 404 nm; 4-nitrophenyl phosphate was eluted at 5 min and could be monitored at 311 nm. Samples of 4-nitrophenyl phosphate obtained from several sources contained 0.3 to 7.8 mole of 4-nitrophenol per mole of 4-nitrophenyl phosphate.
Inhibition by concanavalin A as the basis for a specific assay of serum 5'-nucleotidase activity.
Authors: Zygowicz E R , Sunderman F W , Horak E , Dooley J F 
Published: January 2020

Abstract
Concanavalin A inhibits serum 5'-nucleotidase activity, without causing significant inhibition of alkaline phosphatase activity. This observation serves as the basis for a new method for assaying the 5'-nucleotidase activity in serum, which depends upon the difference between the enzymic hydrolysis of adenosine-5'-monophosphate in the presence and absence of concanavalin A. A denosine released by the 5'-nucleotidase reaction is deaminated by a coupled reaction with adenosine deaminase to liberate inosine and ammonia, and ammonia is measured colorimetrically by the Berthelot reaction. In sera from 40 healthy adult persons, 5'-nucleotidase activity averaged 6.4 U/liter (SD, +/-2.0; range, 3-12). In sera from 100 patients, measurements of 5'-nucleotidase activity by the new assay averaged 8% lower than by a generally accepted method in which phenyl phosphate is used to suppress hydrolysis of adenosine-5'-monophosphate by alkaline phosphatase activity. The clinical validy of the new assay was tested by measuring serum 5'-nucleotidase activities in rats with bile duct ligation and in rats treated with thioacetamide to induce hepatocellular injury.
Radioimmunoassay for normalized thyroxine with use of Sephadex columns.
Authors: Goedemans W T , Bartels P C , Roijers A F 
Published: January 2020

Abstract
We describe a reproducible radioimmunoassay, with use of Sephadex columns, for measuring normalized thyroxine. In comparison with a competitive protein-binding procedure, the present method is more specific because antibody rather than thyroxine-binding globulin is responsible for the competition between endogeneous and tracer thyroxine. In barbital buffer, various concentrations of thyroxine binding pre-albumin and albumin had no influence on the results. Values obtained by the present method correlated well with those by the free thyroxine index and a generally accepted thyroxine normalized method.
Diminished cap formation in lymphocytes from patients and carriers of Duchenne muscular dystrophy.
Authors: Verrill H L , Pickard N A , Gruemer H D 
Published: January 2020

Abstract
Currently, the most useful clinical laboratory aid in establishing the carrier state of Duchenne muscular dystrophy is to determine creatine kinase (EC 2.7.3.2) activity in the plasma. The considerable overlap between plasma creatine kinase activities of controls and of carriers at the childbearing age contributes appreciable difficulty to genetic counseling of potential carriers. The consistent failure of lymphocyte cap formation in Duchenne muscular dystrophy patients and carriers in this study suggests a valuable tool for the confirmation of the carrier state.
Activation of alanine aminotransferase in serum by pyridoxal phosphate.
Authors: Lustig V 
Published: January 2020

Abstract
Alanine aminotransferase activity in serum increases significantly when serum is incubated with pyridoxal phosphate. The increase depends on the L-alanine concentration in the final assay mixture, being greatest at 800 mmol/liter. Preincubation of 22 normal sera, in a 10:1 ratio with an 8.09 mmol/liter pyridoxal phosphate solution, resulted in an increase in the alanine aminotransferase activity from 10.5 +/- 4.9 U/liter (mean +/- SD) to 28.4 +/- 5.3 U/liter, an increase of 170%. The absolute amount of apoalanine aminotransferase is relatively constant over a wide range of enzyme activities.
Quantitative gas-chromatographic flame-ionization method for chloramphenicol in human serum.
Authors: Least C J , Wiegand N J , Johnson G F , Solomon H M 
Published: January 2020

Abstract
We describe a flame-ionization gas-chromatographic procedure for determination of the potentially toxic antibiotic, chloramphenical, in serum. The serum (500 mul) is extracted into ethyl acetate and nonpolar impurities are subsequently partitioned into hexane. The drug is chromatographed as its bis-trimethylsilyl derivative, with the analog thiamphenicol as the internal standard. Within-run precision (CV) is 4.4% at a serum concentration of 41 mg/liter and 9.2% at a concentration of 5 mg/liter. Over a six-month period, the run-to-run variation was 5.1% at 40 mg/liter (n = 24). Results by the gas-chromatographic method compared well with those by an established colorimetric procedure; mean concentrations for the comparison samples in the two procedures were 18.4 mg/liter and 17.6 mg/liter, respectively (n = 27), with a coefficient of correlation of 0.998. The gas-chromatographic method is more precise and specific than classical microbiological procedures and is suitable for routine therapeutic monitoring of serum chloramphenicol concentrations.
Purification and iodination of antibody for use in an immunoradiometric assay for serum ferritin.
Authors: Gonyea L M 
Published: January 2020

Abstract
Antibodies were purified by affinity chromatography and radioiodinated by a conjugation method for use inthe immunoradiometric assay for serum ferritin. These procedures are simpler and more reproducible than those described earlier, and the radiolabeled preparations were usable for at least 13 weeks.
Urinary excretion of immunologically reactive metabolite(s) after intranasal administration of cocaine, as followed by enzyme immunoassay.
Authors: Van Dyke C , Byck R , Barash P G , Jatlow P 
Published: January 2020

Abstract
Using the enzyme immunoassay technique (EMIT), we determined the time course of urinary excretion of benzoylecgonine in 16 surgical patients and three volunteers who received intranasal cocaine. After doses varying from 13 to 130 mg, the test for benzoylecgonine was positive in 1 to 4 h, peaked at about 10 to 12 h, remained positive for 18 to 27 h, and became negative after about 17 h. This information should be considered by drug dependency treatment programs in which the EMIT procedure is used to screen urines for cocaine use.
Glyceraldehyde-phosphate dehydrogenase (total and isoenzyme activity) in the early diagnosis of myocardial infarction.
Authors: Griffiths J , Shaw S 
Published: January 2020

Abstract
Enzyme "panels," in which creatine kinase and lactate dehydrogenase activities in serum are measured, are useful indicators of myocardial infarction. We examined a further enzyme, glyceraldehyde-phosphate dehydrogenase (EC 1.2.1.12), by comparison with creatine kinase (EC 2.7.3.2), in the early diagnosis of such infarctions. Results indicate that this total dehydrogenase appears in the serum before total creatine kinase activity; however, the lack of cardio-specificity relating to the dehydrogenase isoenzyme fraction 2 in comparison to the creatine kinase MB band is a major disadvantage, as is its relatively poor in vitro stability. We conclude that measurement of this dehydrogenase does not allow a substantially earlier diagnosis of myocardial infarction.
Clinical aspects of porphyrin measurement, other than lead poisoning.
Authors: Lamon J M 
Published: January 2020

Abstract
Measurement of porphyrins and porphyrin precursors has clinical significance beyond the detection or confirmation of lead poisoning. The porphyric diseases of man are characterized by the presence of a specific clinical syndrome and demonstration of abnormal porphyrin excretion or accumulation in the tissues. In addition, porphyrins accumulate in other disorders that are unrelated to lead poisoning or the porphyrias. These causes of erythrocyte porphyrin accumulation, porphyrinuria, and the porphyrias are discussed.
Free erythrocyte porphyrins in the detection of undue absorption of Pb and of Fe deficiency.
Authors: Piomelli S 
Published: January 2020

Abstract
A fluorometric assay for free erythrocyte porphyrins (FEP) is described in detail, the direct test being used for the analysis of blood specimens collected with anticoagulants and the spot test for analysis of blood specimens collected on filter paper. A method for determining the amount of blood absorbed by different lots of filter paper is described.
The hematofluorometer.
Authors: Blumberg W E , Eisinger J , Lamola A A , Zuckerman D M 
Published: January 2020

Abstract
A portable filter fluorometer, the hematofluorometer--which utilizes "front face" optics, internal standards, and digital computation capabilities--has been specifically designed for the rapid (approximately 5 s) assay of erythrocyte zinc protoporphyrin in unprocessed blood. A small (unmeasured) drop of blood, such as is obtained from a finger puncture, is placed on disposable cover slip and inserted in the sample holder of the instrument. The operator pushes the holder of the instrument. The operator pushes the holder, which also holds the permanent blank and standard, into the instrument. Zinc protoporphyrin concentration is automatically and instantaneously computed and the value is displayed on a digital readout as micrograms of zinc protoporphyrin per deciliter of blood for some standard hematocrit. No calibration adjustment need be performed by the operator. The hematofluorometer is designed for "field" use as well as for laboratory assays.
Increased serum carnitine concentration in renal insufficiency.
Authors: Chen S H , Lincoln S D 
Published: January 2020

Abstract
We measured serum carnitine in groups of patients with various diseases. The concentration was frequently above normal in patients with renal insufficiency. The clinical significance of such an increase in renal insufficiency may be analogous to that of increases in urea nitrogen, creatinine, or uric acid in the serum.
Enzymic measurement of cholesterol in serum with the CentrifiChem centrifugal analyzer.
Authors: Pesce M A , Bodourian S H 
Published: January 2020

Abstract
Cholesterol is measured by mixing 5 mul of sample with 350 mul of a reagent consisting of phenol, 4-aminoantipyrine, and the enzymes cholesterol oxidase, cholesterol esterase, and peroxidase. After 12 min, the resulting quinoneimine is measured at 520 nm. Readings and cholesterol concentrations are linearly related up to 4.0 g/liter. Lipemic sera and samples containing uric acid (up to 200 mg/liter), hemoglobin (up to 1 g/liter), and certain drugs (clofibrate, phenobarbital, nicotinic acid, Ketochol, Ovral-28), gave no interference. Abnormally high concentrations of bilirubin and ascorbic acid in serum lowered the cholesterol values. This enzymic assay, compared with the method of Abell and with a rate method that uses the Hantzsch reaction, gave correlation coefficients of 0.987 and 989, respectively.
L-p-Bromotetramisole, a new reagent for use in measuring placental or intestinal isoenzymes of alkaline phosphatase in human serum.
Authors: Van Belle H , De Broe M E , Wieme R J 
Published: January 2020

Abstract
L-p-Bromotetramisole is proposed as a new reagent for use in determining intestinal and (or) placental isoenzymes of alkaline phosphatase in human serum. Its main advantage over L-phenylalanine is its high discriminating potency at very low concentrations. For highest accuracy, the samples may even be "titrated" with the inhibitor. Analytical recoveries of intestinal and placental isoenzymes in serum are complete, and results correlate well with those by other methods. At the appropriate concentrations, L-p-bromotetramisole gives nearly identical results on a variety of sera, irrespective of the buffer used. Within-day CV's were 6.1 and 2.1 for 20% and 60% of the resistant isoenzyme activity, respectively. The day-to-day CV was 3.45 for a sample containing 53.3% of the resistant isoenzyme (n=15). The well-known increase in placental isoenzyme activity with time of gestation could be confirmed on 612 sera from pregnant women. The activities of the intestinal isoenzyme in sera from healty blood donors (n = 126) and hospitalized patients (n = 135) agree with previous findings obtained by the other techniques.
Ion pair extraction technique with azure A, for differentiating biles of normal subjects and patients with liver disease from patients with Crohn's disease with small bowel involvement.
Authors: Webb G R , Macdonald I A , Williams C N 
Published: January 2020

Abstract
The ion pair extraction technique with Azure A solution, chloroform/methanol (equal volumes), and dilute sulfuric acid, was used to study bile-rich duodenal aspirates of (a) healthy volunteers and patients with (b) cholestatic liver disease, (c) Crohn's disease with small bowel involvement, and (d) those with primarily colon involvement. Duplicate aliquots of extracted duodenal aspirates from these four groups were subjected to ion pair extraction, with and without prior acetylation, and the absorbance ratios at 645 nm without acetylation/with acetylation ("acetylation index") compared; values (+/- SD) obtained were 0.052 +/- 0.0098, 0.038 +/- 0.014, 0.136 +/- 0.048, and 0.077 +/- 0.056, respectively, for the four groups. The acetylation index for group c was significantly (P less than 0.001) different from that of groups a and b. All other intergroup comparisons were not significant. The acetylation index correlated positively (r = 0.922) with the ratio of glycine- to taurine-conjugated bile acids, measured independently, implying that it reflects this ratio.
Use of equilibrated blood for internal blood-gas quality control.
Authors: Leary E T , Delaney C J , Kenny M A 
Published: January 2020

Abstract
We have used equilibrated human blood for blood-gas quality control since 1970. In blood equilibrated 24 h after shedding, gas tensions are stable for 4 to 6 h at 0 to 4 degrees C; each control specimen is analyzed several times during that period to resolve malfunctions, etc. Three-fourths of all errors in gas-tension measurement detected with equilibrated blood were detected with the highest-tension controls. Equilibrated blood controls signal about one error every 14 d on each instrument. For more complete quality control, we supplement analysis of equilibrated blood with other sorts of controls, comparing results obtained by assaying each patient's specimen on two instruments being our most effective adjunct. Such comparisons have identified erroneous assays in 3.9% of the specimens tested. The magnitude of interinstrument discrepancies (random errors) have ranged from 9 to 100% of the appropriate determinations. We use control data derived from equilibrated blood analysis for special management purposes (evaluating instruments, quantitating micro- vs. macro-sampling discrepancies, and decreasing instrument-repair costs).
Intra-individual variation in the concentrations of IgA, IgG, IgM, and complement component C3 in serum of a normal adult population.
Authors: Butts W C , James G E , Keuhneman M 
Published: January 2020

Abstract
A recent study [Clin. Chem. 22, 1635 (1976)] reported intra-individual variation in 10 serum proteins to be much smaller than interindividual variation. We report results of a similar study involving about 700 apparently healthy adults in whom we estimated the relative magnitude of the intra- and interindividual variation in serum IgA, IgG, IgM and complement component C3. Specimens were collected from each subject weekly for as long as 10 weeks (average, four weeks). The four serum proteins were quantitated by radial immunodiffusion by the maximal-diffusion technique. Traditional 95% reference intervals were computed relative to WHO reference preparations for the immunoglobulins. For C3, the reference interval was computed relative to a commercial reference preparation. We, too, found the ratios of intra-individual to interindividual variation for adults to be so small that the traditional reference intervals do not have the assumed diagnostic sensitivities. Furthermore, these ratios did not change after dividing the study population into subgroups according to sex and age; evidently such subgrouping do not improve the diagnostic sensitivity. The relatively small intra-individual variations were also observed at the extremes of protein concentration ranges.
Cortisol production rate determined by radio gas-chromatography.
Authors: Derks H J , Muskiet F A , Wolthers B G , Thijssen J H , Drayer N M 
Published: January 2020

Abstract
We describe a ratio gas-chromatographic method for determination of cortisol production rate by measuring the isotope dilution of urinary cortisol metabolites. The method was calibrated by analyzing [3H]tetrahydrocortisol and [3H]tetrahydrocortisone of known specific activities. Results are reasonably well reproducible, the coefficients of variation ranging from 8-15% of allotetrahydrocortisol/tetrahydrocortisol and from 9-19% for tetrahydrocortisone. Correlation coefficients were 0.966 and 0.998 for tetrahydrocortisone and allotetrahydrocortisol/tetrahydrocortisol, respectively, when the method was compared with a method involving thin-layer chromatography and colorimetry. Only one chromatographic step is needed for both purification and quantitation, thus time and effort are saved.
Beta-lipoprotein cholesterol quantitation with polycations.
Authors: Heuck C C , Schlierf G 
Published: January 2020

Abstract
We compared direct determination of beta-lipoprotein cholesterol after selective extraction of very-low-density and high-density lipoproteins from serum with poly(ethyleneimine) and a cation-exchange resin with the classical quantitation after lipoprotein fractionation with the ultracentrifuge. At beta-lipoprotein cholesterol concentrations between 1.50 and 5.00 g/liter the correlation is linear (r = 0.95). The precision for the extraction procedure is as good (CV 2.4-2.8%) as for the quantitation by ultracentrifugation (CV 3.2-6.0%). From solutions of isolated lipoproteins, very-low-density lipoproteins are 93% extracted and high-density lipoproteins 60%, but low-density-lipoproteins only 5%. The molecular mechanism of the extraction is supposed to be due to both hydrophobic interaction of long-chain fatty acid residues and ionic interaction of phospholipids located at the surface of very low-density and high-density lipoproteins and the lipophilic polycation.