bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photometric Determination of Total Protein in Lipemic Sera
Authors: Chromy Vratislav , Fischer J 
Published: January 2020

Abstract
We compared various procedures and biuret reagents suggested for determination of protein in lipemic sera. A modified procedure, consisting of the precipitation of serum protein with acetone and dissolution of the pre¬cipitate in a biuret reagent, has been developed. The sample (0.02 ml) is mixed with 0.1 ml of distilled water and 2 ml of acetone. The mixture is shaken, centrifuged, and the precipitate dissolved in 1.5 ml of ethylenediaminete¬traacetate-chelated biuret reagent. This method is suitable for both clear and lipemic sera. Values obtained with the procedure proposed are in good agreement with values by the Kjeldahl method.
Stability of commonly used thiols and of human creatine kinase isoenzymes during storage at various temperature in various media.
Authors: Nealon D A , Henderson A R 
Published: January 2020

Abstract
We assessed the stability--at 20, 4 --20, and --80 degrees C--of 2-mercaptoethanol, dithioerythritol, and dithiothreitol, and of semi-purified creatine kinase isoenzymes of human origin in the presence and absence of the three compounds. The isoenzymes plus the sulfhydryl compounds were also assessed an aqueous buffer, in heat-inactivated pooled sera, or in fresh pooled sera with low endogenous total creatine kinase. We also examined the influence of thawing conditions from--20 or--80 degrees C, of fast freezing, and of exposure to fluorescent light. At 20 and 4 degrees C some--SH groups are oxidized. At--20 and--80 degrees C this loss is diminished. It is a function of both temperature and diluent. For stability, creative kinase isoenzymes stored at any temperature require the presence of a suitable sulfhydryl compound. Periodic addition of fresh sulfhydryl solutions stabilized creatine kinase isoenzymes suspended in the two protein-based diluents by 10-30%; for those in an aqueous buffer such additions decreased the activity to stored creatine kinase isoenzymes. Fast freezing does not increase recovery of creatine kinase isoenzyme activity over slow freezing at--80 or--20 degrees C. Thawing should be done as infrequently as possible and should be done rapidly, at 37 degrees C, for the residual enzyme activity to be maximal.
Intra-individual variation of some serum constituents and its relevance to population-based reference ranges.
Authors: Pickup J F , Harris E K , Kearns M , Brown S S 
Published: January 2020

Abstract
The advent of high-capacity multi-channel analyzers allows estimation of long-term variability in serum constituents of large numbers of subjects. By frozen storage of specimens with subsequent analysis in a single machine run, long-term analytical variation may be eliminated, thus sharpening the estimates of intra-individual variation. In the present study we used the Vickers M-300 analyzer to obtain the data for such estimates from 37 male volunteers, each bled once a week for 22 weeks. Secimens were analyzed in random order to eliminate any biasing effect of analytical drift during the 4-h machine run. Ten serum constituents were measured. Storage-induced linear trends were small or negligible during the period of specimen collection. Using the ratio of average within-subject variance to the variance among subjects as a guide, serum alkaline phosphatase was found to show the greatest individuality, sodium and potassium the least. Other constitutents showed varying degrees of individuality, but for all these analytes, the usual population-based reference ranges were found to be either insensitive or irrelevant to the study of concentration changes over time within most healthy subjects. Our results generally confirmed those of smaller but comparable earlier studies.
Myoglobin concentrations and muscle-enzyme activities in serum after myocardial infarction and cardiac arrhythmia.
Authors: Rosano T G , Sanders L A , Johnson E S , Kenny M A , Clayson K J , Strandjord P E 
Published: January 2020

Abstract
Sera from patients with myocardial infarction and cardiac arrhythmias were analyzed for myoglobin concentration and the activities of total creatine kinase, creatine kinase isoenzyme-2, and lactate dehydrogenase isoenzyme-1 at the time of hospital admission and during the first few days of hospitalization. The nine patients with a final diagnosis of myocardial infarction had abnormally high values for total creatine kinase, creatine kinase-2, lactate dehydrogenase-1, and myoglobin. Myoglobin concentrations were highest on admission in six patients and on the day after admission in the other three patients. Creatine kinase-2 manifested maximum activity on the day after admission for all patients with myocardial infarction. Lactate dehydrogenase-1 did not reach maximal values until the second or third day after admission. The six patients with arrhythmias did not show any significant increases in creatine kinase-2 or lactate dehydrogenase-1. Myoglobin and total creatine kinase, however, were increased in the four patients who had received cardioversion. The specificity and diagnostic usefulness of these serum measurements are discussed.
Comparison of several methods for semiquantitative determination of urinary protein.
Authors: Gyure W L 
Published: January 2020

Abstract
Two types of urine protein dipsticks and the sulfosalicylic acid method were compared for their accuracy and specificity, with use of urine samples supplemented with various proteins. Dipsticks yield accurate results when the protein under consideration is restricted to albumin; the sulfosalicylic acid method accurately determines many kinds of proteins in addition to albumin. Detergents affect each of the methods, but changes in salt concentration only affect results by dipstick procedures. Dipsticks, which are based on the protein-error principle for indicators, are subject to some of the conditions that apply to the bromcresol green method for serum albumin determination.
A stopped-flow clinical analyzer in which immobilized-enzyme reaction loops are used.
Authors: Joseph M D , Kasprzak D J , Crouch S R 
Published: January 2020

Abstract
A stopped-flow clinical analyzer is described that makes use of a reaction loop containing immobilized enzyme(s) for the determination of the analyte/substrate. The analyzer has been evaluated by determining glucose with immobilized glucose oxidase. The stopped-flow mixing system was constructed at a current cost of less than $500. The analyzer separates the enzymatic reaction from a followup, spectrophotometric indicator reaction. This separation allows the enzymatic reaction to be used in either a fixed-time, kinetic mode or in an equilibrium mode. Likewise, the indicator reaction can be used in either mode. Results for glucose in blood serum indicate that good precision and accuracy can be obtained.
Micromethod for measuring hexachlorophene in whole blood by gas-liquid chromatography.
Authors: Dodson W E , Tyrala E E , Hillman R E 
Published: January 2020

Abstract
We describe a micromethod for measuring hexachlorophene by use of gas-liquid chromatography with a 63Ni electron capture detector. The procedure requires 100 micronl of blood for extractions of hexachlorophene, and dichlorophene is added as an internal standard. CV is 3.4% over the concentration range of 500 to 1300 microng of hexachlorophene per liter of whole blood. This procedure permits repeated measurements of hexachlorophene in newborns who are being washed with soap containing hexachlorophene.
Evaluation of the dual-precipitation method by comparison with the ultracentrifugation method for measurement of lipoproteins in serum.
Authors: Demacker P N , Vos-Janssen H E , Jansen A P , van 't Laar A 
Published: January 2020

Abstract
We evaluated the dual-precipitation method for quantitative measurement of lipoproteins as described by Wilson and Spiger [J. Lab. Clin. Med. 82, 473 (1973)] for normo- and hyperlipemic sera, by comparison with the results obtained with ultracentrifugation. If serum with an above-normal triglyceride concentration is analyzed, the very-low-density lipoprotein cholesterol value obtained with the precipitation method is usually too low. For measurement of high-density lipoprotein cholesterol the ultracentrifugation and precipitation procedures give comparable results, but the latter method is preferred because sinking pre-beta-lipoproteins present in the high-density lipoprotein fraction isolated by means of the ultracentrifuge may result in falsely high values for cholesterol in that fraction. Therefore, at least for the determination of very-low-density lipoprotein cholesterol in hyperlipemic serum, the use of an ultracentrifuge remains necessary. Because few laboratories have an ultracentrifuge at their disposal, it seemed important to look at the stability of sera in view of the forwarding of samples. Also, a way of increasing the efficiency of the ultracentrifuge was studied. Sera can be stored for a week at 4 degrees C or for 54 h at room temperature without noticeable effect on lipoprotein values. Moreover, reliable values can be obtained with an ultracentrifugation time of 8 h (0.8 X 10(8) g-min).
Radioimmunoassay for free and conjugated urinary metanephrine.
Authors: Lam R W , Artal R , Fisher D A 
Published: January 2020

Abstract
We describe a convenient and specific radioimmunoassay for urinary metanephrine, in which we used an antiserum generated in rabbits by injecting with synephrine conjugated to bovine serum albumin as described by Grota and Brown [Endocrinology 98, 615 (1976)]. The antiserum is specific for metanephrine and epinephrine. Epinephrine cross reaction is minimized to 1% by adding 2 ng of epinephrine to each assay tube. Incubation time is 12 h. The sensitivity of the assay is 40 pg. Within-and between-assay coefficients of variation are 7.0 and 9.7%, respectively. We assayed first-voided morning urine and 24-h urine specimens from 15 normal subjects before and after acid hydrolysis, to assess total and free metanephrine concentrations. Mean (+/-SD) total and free urinary metanephrine excretion were 17 +/- 11 and 3.5 +/- 1.0 micrograms/24 h in these subjects; corresponding values for the morning specimens were 13.4 +/- 8.3 and 3.5 +/- 1.5 micrograms/liter, respectively.
Optimal conditions for assaying human lactate dehydrogenase by the lactate-to-pyruvate reaction: Arrhenium relationships for lactate dehydrogenase isoenzymes 1 and 5.
Authors: Buhl S N , Jackson K Y , Lubinski R , Vanderlinde R E 
Published: January 2020

Abstract
Optimal reaction conditions to sassay human lactate dehydrogenase (lactate-to-pyruvate) were established for isoenzymes 1 and 5 at 25, 30, and 37 degrees C in diethanolamine and 2-amino-2-methyl-1,3-propanediol. Different substrate concentrations are required at each temperature. The conditions permit measurement of lactate dehydrogenase 1 and 5 with the lowest substrate concentrations that allow for the highest equal sustainable efficiency in measuring both isoenzymes. About 95% of each isoenzyme activity is measured if the assay is performed within the first minute after the reaction is initiated even for activities as high as triple the upper limit of normal. The Arrhenius relationship is different for each isoenzyme, but results obtained for each at one temperature can be compared with results at another temperature by use of simple conversion equations. Assays at 25 and 30 degrees C are more economical and less variable than assays at 37 degrees C.
Improved assessment of plasma lipoprotein patterns. III. Direct measurement of lipoproteins after gel-electrophoresis.
Authors: Neubeck W , Wieland H , Habenicht A , Müller P , Baggio G , Seidel D 
Published: January 2020

Abstract
Based on a previously described technique [Clin. Chem. 19, 737 (1973)] of precipitating plasma lipoproteins with polyanions after their electrophoretic separation in gels, a new method is presented for measuring normal plasma lipoproteins densitometrically. The method is fast and easy; the CV for beta-, pre-beta-, and alpha-lipoproteins was less than 5% in one series. Results are linearly related to concentration up to 10 g of total lipoprotein per liter. No unusual equipment is required. Standardization is done with the aid of a commercially available filter. Total plasma cholesterol and cholesterol calculated from quantified lipoprotein fractions were highly (r = 0.963) correlated.
Simultaneous determination of iron, zinc, selenium, rubidium, and cesium in serum and packed blood cells by neutron activation analysis.
Authors: Versieck J , Hoste J , Barbier F , Michels H , De Rudder J 
Published: January 2020

Abstract
We determined the iron, zinc, selenium, rubidium, and cesium concentrations in serum and packed blood cells by instrumental neutron activation analysis without chemical separations. Lyophilized samples were irradiated for 12 days at a flux of 10(13) neutrons-cm-2-s-1, mineralized by wet digestion, and measured two times with a high-resolution Ge(Li) detector--for 6 h about a month after the irradiation and for 15 h two or three months after the irradiation, The following values were obtained: 163 +/- 0.43 mg/liter (serum iron), 1025 +/- 136 mg/kg wet wt (packed cells iron), 1¿ +/- 0.20 mg/liter (serum zinc), 11.15 +/- 1.83 mg/kg wet wt (packed cells zinc), 0.13 +/- 0.02 mg/liter (serum selenium), 0.16 +/- 0.03 mg/kg wet wt (packed cells selenium), 0.17 +/- 0.04 mg/liter (serum rubidium), 4.28 +/- 0.98 mg/kg wet wt (packed cells rubidium), 0.74 +/- 0.20 microgram/liter (serum cesium), and 4.82 +/- 2.10 microgram/kg wet wt (packed cells cesium).
Measurement of thiamylal and thiopental in plasma by electron capture and flame photometric gas-liquid chromatography.
Authors: Smith R H , MacDonald J A , Thompson D S , Flacke W E 
Published: January 2020

Abstract
We describe an isothermal gas-liquid chromatographic procedure developed for measuring thiamylal and thiopental in plasma. The unchanged drug is extracted into ethyl acetate from acidified plasma, together with an internal standard. The solvent is removed, the residue methylated, aliquots, diluted with benzene, are injected into a 183-cm gas-liquid chromatographic column containing 3% OV-17. Sensitivity of detection is in the nanogram to picogram range.
Elimination of glucose interference and improved precision in a continuous-flow analysis for inulin.
Authors: Torelli J A , Middleton B , Stein R M 
Published: January 2020

Abstract
A modified fermentation procedure based on one described by Homer Smith in his textbook was used to eliminate glucose interference in the automated detrmination of inulin. The manifold of Fjeldbo and Stamey [J. Lab. Clin. Med. 72, 353 (1968)] was modified to enable us to insert the fermentation procedure without sacrificing precision in continuous-flow analysis for inulin. Analytical recoveries of inulin from plasma and urine with the modified manifold were 100.1 +/- 0.8% (SD) and 99.9 +/- 1.6%. Corresponding recoveries of inulin from specimens of plasma and urine containing 5 g of glucose per liter and treated with yeast were 99.6 +/- 1.5% and 100.0 +/- 1.6%.
Therapeutic monitoring of tricyclic antidepressants in plasma by gas chromatography.
Authors: Dorrity F , Linnoila M , Habig R L 
Published: January 2020

Abstract
We describe a comprehensive gas chromatographic analysis for therapeutic concentrations of amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin in plasma, with use of a nitrogen detector. All these drugs are extracted and chromatographed under identical conditions. Each tertiary amine tricyclic is well resolved from its secondary amine metabolite on a mixed-phase column and the concentrations of both are determined simultaneously, without derivatization. The lower limit of sensitivity is 10 microgram/liter of plasma (2-ml sample). Analytical recoveries of the tertiary and secondary amines are 100 and 80%, respectively. Between-run CV's for all of the drugs ranged between 5 and 7%.
Positive interference with the Jaffé reaction by cephalosporin antibiotics.
Authors: Swain R R , Briggs S L 
Published: January 2020

Abstract
Cephaloglycin, cephalothin, cephaloridine, cefoxitin, and cephacetrile are cephalosporin antibiotics that react with alkaline picrate solution to give a creatinine-like response. The mechanism of this reaction is not known, and several structurally similar compounds do not react under these same conditions. Because large quantities of a cephalosporin antibiotic may be administered to a patient with limited ability to excrete the drug (as occurs with compromised renal function), the magnitude of this interference can be appreciable. It does not appear possible to avoid the cephalosporin-caused interference by the use of "kinetic" creatinine methods.
Heparin pretreatment suppresses norepinephrine concentrations in dogs in endotoxic shock.
Authors: Devereux D F , Michas C A , Rice S 
Published: January 2020

Abstract
Mongrel dogs were treated intravenously with either 1000 units of beef-lung heparin per kilogram of body weight or with isotonic saline, before intravenous administration of E. coli endotoxin. We found significant differences in circulating norepinephrine concentrations between a heparin-pretreatment group (1.89 +/- 0.39 microgram/liter) and the control group (9.83 +/- 4.64 microgram/liter), but none with respect to epinephrine. Systolic blood pressures at 360 min were also significantly (P less than 0.05) different, 148 +/- 6 mmHg as compared with 118 +/- 13.4 mmHg. Evidently heparin pretreatment can decrease circulating norepinephrine concentrations in the endotoxic state and changes in circulating catecholamine concentrations can affect physiological variables.
Column cation-exchange separation of melanin-related metabolites in urine from cases of melanoma.
Authors: Banda P W , Sherry A E , Blois M S 
Published: January 2020

Abstract
We describe recent developments in the use of a stable free radical, diphenylpicrylhydrazyl, as a colorimetric detector of reducing metabolites in melanoma urines. A procedure for buffering aqueous/solvent reagent solutions is presented, and examples of the baseline stability achieved for reference chromatograms and urine samples are provided. Chromatograms of phaeomelanin precursors and of an extract of a highly pigmented hamster melanoma are also presented. Identities are tentatively assigned for some of the chromatographic peaks that have previously been correlated with disease, including isomers of cysteinyldopa, and observations of new pigment- and tumor-related metabolites in the chromatograms are noted.
Enzyme immunoassays with the miniature centrifugal fast analyzer.
Authors: Lasky F D , Ahuja K K , Karmen A 
Published: January 2020

Abstract
We studied the EMIT (Enzyme Multiplied Immunoassay Technique, Syva) procedures for the assay of phenytoin and phenobarbital in serum, adapting them to the miniature Centrifugal Fast Analyzer. For different concentrations of drug, each rate of reaction decreased continuously with time, tending to converge on a single common value. The rate was most affected by the concentration of drug almost immediately after the reagents were mixed, less so thereafter. The antibody evidently is present in sufficient excess to bind all the enzyme-labeled drug ordinarily present, but the antibody-bound enzyme was only 75% inhibited; this helps explain the appreciable residual activity when no drug is present. The reaction course was the same whether the serum and enzyme-labeled drug were added to the antibody sequentially or simultaneously, which suggests that antibody is bound to drug appreciably faster than to enzyme-labeled drug. The reaction rates 15 to 30 s after mixing were used as the measure of the drug concentrations. These results were confirmed by noting the rates at successive 15-s intervals. The analyzer yielded a run-to-run CV of 10% for phenobarbital at 30 mg/liter, and 9% for phenytoin at 15 mg/liter, as compared to the 15% quoted by Syva.
Microchemical analytical techniques of potential clinical interest.
Authors: Glick D 
Published: January 2020

Abstract
Microchemical techniques with the capability of single-cell analysis will become increasingly important in clinical laboratory practice. One of the current moves underway in this direction is determination of enzyme activities of cells by microscale spectrophotometry and spectrophotofluorometry for prenatal diagnosis of inherited enzyme deficiencies. Three less-common microanalytical techniques are considered here that are of potential interest in laboratory medicine. The first is dilatometry, which provides a means for enzyme or substrate assay involving measurement of the change in volume or density accompanying chemical reaction in solution. In this connection, the measurement of specific gravity itself to obtain certain chemical information is also of interest. The second of these techniques is the use of spectrophotometry to measure oxygen uptake for functional assays of cells. The third is the use of luminometry in a general system of analysis for determination of many important biochemical substances and activities. Each of these techniques can be used for microscale analysis without sacrifice of precision or accuracy; each is relatively simple, instrumentally ant technically, and could be automated.
Enzyme kinetics in single cells: concept and model.
Authors: Markovic N , Markovic O , Young D S 
Published: January 2020

Abstract
We describe a technique whereby it is possible to measure enzyme activity in a singel cell. The model chosen involved the measurement of myeloperoxidase activity in a polymorphonuclear neutrophil leukocyte. Details of the apparatus are described. The experiments necessary to optimize the reaction conditions are summarized. The nature of the phases of the reaction are described. The technique appears to have further application in measurement of the activities of other enzymes in leukocytes or other cells.
Nucleotide pyrophosphatase and phosphodiesterase. I. Organ distribution and activities in body fluids.
Authors: Haugen H F , Skrede S 
Published: January 2020

Abstract
We estimated nucleotide pyrophosphatase and phosphodiesterase I activities in human and rat organs and in body fluids from man and dog. The highest organ activities were found in epididymis, kidney, liver, and intestine. In body fluids, the activity was highest in seminal plasma, followed by intestinal lymph, serum, heart lymph, cerebrospinal fluid, milk, and urine. The ratio nucleotide pyrophosphatase/phosphodiesterase I and the urea resistance of phosphodiesterase I differed among human organs, body fluids, and blood cells. Different isoenzymes probably exist. The activities in serum share several properties with those in several organs--e.g. pH-optimum 9.6-9.8, dependency on Zn2+, and the effects of inhibitors. Phosphodiesterase I in erythrocytes, which has not been described previously, differs from enzyme from other sources by lower pH optimum (8.5), dependency on Mg2+, inhibition by Zn2+, and stimulation by dithiothreitol.
Lactate dehydrogenase inhibitors in NADH preparations.
Authors: Margolis S A , Howell B F , Schaffer R 
Published: January 2020

Abstract
The presence of a new lactate dehydrogenase inhibitor on the trailing edge of the NADH peak from chromatography on diethylaminoethyl-celluose [Loshon et al., Clin. Chem., this issue] was verified. It was resolved from the NADH by high-performance liquid chromatography on muBondapak C18. When the new inhibitor was present in a reaction mixture to the extent that, of the initial 260-nm absorbance, about 5% was contributed by the inhibitor, the rate of NADH oxidation by lactate dehydrogenase decreased by 65%. The inhibitor absorbs at 260 and 340 nm, and is different from the Strandjord-Clayson inhibitor [J. Lab. Clin. Med. 67, 144 (1966)] by both types of chromatography. Because this new inhibitor has ultraviolet properties similar to those of NADH and chromatographs with the NADH on DEAE-cellulose, the high-performance liquid chromatographic method must be used to ensure its absence in preparations of NADH used for clinical assay.