bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radioimmunoassay for arginine-vasopressin in cold ethanol extracts of plasma.
Authors: Camps J , Martínez-Vea A , Pérez-Ayuso R M , Arroyo V , Gaya J M , Rivera-Fillat F 
Published: January 2020

Abstract
A radioimmunoassay for arginine-vasopressin in human plasma with use of a commercially available antibody was developed and evaluated. The hormone was extracted from plasma with cold 98% ethanol, which showed a significantly higher (p less than .001) and more precise recovery than with the acetone-ether procedure (65.3 +/- 3.7% vs 50.8 +/- 6.0%, respectively). The sensitivity was 0.31 pg per tube. Results for normal subjects in different physiological conditions and in patients with diabetes insipidus and inappropriate antidiuretic hormone secretion showed the good reliability of the method.
Continuous-flow system for automation of latex immunoassay by particle counting.
Authors: Bernard A M , Lauwerys R R 
Published: January 2020

Abstract
Latex immunoassay is a nonisotopic method based on agglutination, by protein, of calibrated latex particles coated with a specific antibody. The assay has been automated in a simple continuous-flow system by incubating the reaction mixture in a heated mixing coil for 25 min and measuring the agglutination with a cell counter. No external shaking of the latex suspension and no additional reagent is required for the agglutination. The method can accurately and precisely quantify a wide variety of proteins in plasma and urine, including human ferritin, beta 2-microglobulin, retinol-binding protein, and albumin. Depending on the antigen-antibody system, the detection limit ranges from 10(-10) to about 10(-12) mol/L. Within- and between-assay CVs are less than 10%. In the assay of ferritin, sera are pretreated to eliminate interferences from chylomicrons, complement, and rheumatoid factor.
Evaluation of serum gamma-glutamyltransferase by electrofocusing, and variations in isoform patterns.
Authors: Lilja H , Jeppsson J O , Kristensson H 
Published: January 2020

Abstract
Serum gamma-glutamyltransferase (EC 2.3.2.2) showed microheterogeneity on electrofocusing, owing to variations in sialic acid content. We investigated the isoform patterns of papain-treated serum samples on agarose gels containing nonionic detergent and ampholytes in the low pH range. Serum from cases of cholestasis show seven bands with gamma-glutamyltransferase activity. These same bands were also found in liver tissue similarly treated, and they had pl values ranging from 3.8 to 4.2. Papain-treated sera that also had been neuraminidase digested showed only a single band, still enzymatically active and with a pl of 5.9. Increased gamma-glutamyltransferase in serum as a result of alcohol abuse was combined with a abnormally high degree of sialylation of the enzyme, giving more anodal isoforms. The decline in the concentration of this enzyme during several weeks of abstinence was accompanied by a gradual decrease in gamma-glutamyltransferase sialyation and the appearance of more cathodal fractions.
Immunoquantification of total apolipoprotein B in serum by nephelometry: influence of lipase treatment and detergents.
Authors: DaCol P , Kostner G M 
Published: January 2020

Abstract
The immunoquantification of total apolipoprotein B in human serum has been evaluated by rate and equilibrium nephelometry. The presence of triglyceride-rich lipoproteins spoiled all immunochemical assays and yielded too-high values for apolipoprotein B. The use of detergents improved the results substantially, but results were inaccurate at high triglyceride concentrations. Of many detergents investigated, only Thesit, Kryo Ebo, and Apovax were useful, decreasing the light-scatter signals almost linearly with increasing detergent concentrations. The regression lines, however, were not parallel among the different apo B-containing lipoproteins. Incubating sera or apo B-containing lipoproteins with bovine milk lipoprotein lipase or bacterial triacylglycerol lipase, at concentrations of 100 kU/L, hydrolyzed all of the triglycerides and most of the phosphatidylcholine within 18 h at 37 degrees C Lipase-pretreatment of samples gave optimal correlation between apo B values as determined by nephelometry with those obtained gravimetrically. We also assessed the influence of sample storage, freezing, and thawing on the nephelometric apo B assays.
Liquid-chromatographic study of fluorescent materials in uremic fluids.
Authors: Swan J S , Kragten E Y , Veening H 
Published: January 2020

Abstract
Using reversed-phase "high-performance" liquid chromatography with fluorescence detection, we separated and identified some naturally fluorescent compounds in uremic serum and hemodialysate from patients with chronic renal disease. Several of the naturally fluorescent compounds were identified as indole derivatives by co-chromatography with authentic standards. In one specific case, the identity was confirmed by an enzymic peak-shift method. Compounds identified included indican, kynurenic acid, tryptophan, and 5-hydroxy-indole-3-acetic acid. Comparison of normal and uremic serum showed that the fluorescent materials are present in significantly greater concentrations in samples from uremic patients.
Improved determination of aluminum in serum by electrothermal atomic absorption spectrophotometry.
Authors: Bertholf R L , Brown S , Renoe B W , Wills M R , Savory J 
Published: January 2020

Abstract
This method for determining aluminum in human serum involves electrothermal atomic absorption spectrophotometry. A longer drying time allows less pre-dilution of the sample, and the method also includes a flush cycle after atomization. Standard-addition methodology is used to eliminate matrix effects and the need for a standard curve. We used this method on serum from 50 normal persons and from 34 patients with chronic renal failure who were on long-term intermittent hemodialysis. The mean normal serum aluminum concentration was 6.1 micrograms/L (CV 2.7%), and values for the patients ranged from 13 to 475 micrograms/L.
Evaluation of a direct potentiometric method for sodium and potassium used in the Du Pont aca.
Authors: Koch D D , Parrish D , Ladenson J H 
Published: January 2020

Abstract
We evaluated an accessory that enables the Du Pont aca discrete analyzer to measure Na+ and K+ by direct potentiometry (aca/ISE). Na+ and K+ gave linear responses in both the blood and urine modes, with no carryover. No interfering species were identified in the blood mode. Intra-assay and interassay precision for Na+ and K+ were more than adequate and analytical recoveries comparable to those with flame photometry were found for plasma. The Na+ and K+ values for plasma were comparable with those obtained by use of another direct potentiometric analyzer (the Orion SS-30), but slightly higher than flame-photometric values. Samples from patients with hyperlipemia and multiple myeloma gave clinically relevant values with the aca/ISE, but the flame photometric values were artefactually low. Whole blood could not be accurately analyzed. The aca/ISE is a precise, easy-to-use instrument, which gives values for plasma similar to those obtained with direct potentiometric analyzers. For analysis of urine, certain precautions are necessary.
Reversed-phase liquid-chromatographic simultaneous analysis for thiopental and pentobarbital in serum.
Authors: Kelner M , Bailey D N 
Published: January 2020

Abstract
We describe a reversed-phase liquid-chromatographic assay suitable for therapeutic monitoring of thiopental and pentobarbital simultaneously in human serum. The drugs are extracted from serum at pH 6.6 into n-butyl chloride containing thiamylal and barbital as the respective internal standards. The compounds are back-extracted into dilute sodium hydroxide, an aliquot of which is submitted to chromatography. The lowest measurable concentrations are 1.0 mg/L for thiopental and 2.0 mg/L for pentobarbital. The standard curve is linear from 0 to 100 mg/L for both. Between-run CVs are: at 25 mg/L, 4.1% (thiopental) and 3.2% (pentobarbital); at 50 mg/L, 2.8% (thiopental) and 3.4% (pentobarbital). Data on patients receiving thiopental and pentobarbital illustrate use of the method.
Metabolism of creatinine in vivo.
Authors: Boroujerdi M , Mattocks A M 
Published: January 2020

Abstract
Two forms of radiolabeled creatinine were used in this study, [carbonyl-14C]- and [amidino-14C]creatinine, the latter being synthesized in this laboratory. These labeled compounds were given intravenously to rabbits. Specimens of plasma, urine, feces, and selected tissues were collected. These were liquid-chromatographed and the separated components compared for radioactivity and identity. This first use of amidino-labeled creatinine revealed the metabolic conversion of small amounts of creatinine to an unidentified non-basic compound and guanidinobutyrate in normal rabbits and to guanidinopropionic acid and arginine in a rabbit that had a low creatinine clearance. A mechanism is suggested for this metabolic process. The proposed pathway may be a major route of elimination of creatinine in renal failure.
The succinonitrile triple-point standard: a fixed point to improve the accuracy of temperature measurements in the clinical laboratory.
Authors: Mangum B W 
Published: January 2020

Abstract
In an investigation of the melting and freezing behavior of succinonitrile, the triple-point temperature was determined to be 58.0805 degrees C, with an estimated uncertainty of +/- 0.0015 degrees C relative to the International Practical Temperature Scale of 1968 (IPTS-68). The triple-point temperature of this material is evaluated as a temperature-fixed point, and some clinical laboratory applications of this fixed point are proposed. In conjunction with the gallium and ice points, the availability of succinonitrile permits thermistor thermometers to be calibrated accurately and easily on the IPTS-68.
Sensitive colorimetric assay for angiotensin converting enzyme in serum.
Authors: Neels H M , van Sande M E , Scharpé S L 
Published: January 2020

Abstract
A sensitive colorimetric procedure has been developed for the assay of angiotensin converting enzyme (EC 3.4.15.1) in serum. Serum (10 microL) is incubated for 30 min with hippuryl-glycyl-glycine as described earlier (Clin Chem 28: 1352-1355, 1982). After a Folin-Wu deproteinization, the liberated glycyl-glycine is derivatized with a borate-buffered (pH 9.3) trinitrobenzenesulfonate solution (60 mmol/L) to form trinitrophenyl-glycylglycine, the absorbance of which is read at 420 nm vs a serum blank. The linear range extends to an activity of more than 900 U/L of serum and the detection limit is less than 4 U/L. The mean activity for serum from 50 blood bank donors and 25 patients with active sarcoidosis was 281 (SD 77) and 693 (SD 81) U/L, respectively. The method demonstrates good precision (CVs less than 2.8%) and correlates well (r = .99) with results from a "high-pressure" liquid chromatographic procedure for determining hippuric acid. In addition, the proposed method is widely applicable, involving only commonly available apparatus.
Gas-chromatographic determination of cholesterol sulfate in plasma and erythrocytes, for the diagnosis of recessive X-linked ichthyosis.
Authors: Muskiet F A , Jansen G , Wolthers B G , Marinkovic-Ilsen A , van Voorst Vader P C 
Published: January 2020

Abstract
We describe a rapid method for determining cholesterol sulfate in plasma and erythrocytes. After its single-step isolation by means of anion-exchange chromatography cholesterol sulfate is hydrolyzed, trimethylsilylated, and determined by gas chromatography with flame ionization detection. 5 beta-Cholestan-3 alpha-ol sulfate is used as internal standard. The method enables simultaneous determination of dehydroepiandrosterone sulfate in plasma. We applied it for the diagnosis of seven patients with recessive X-linked ichthyosis. Concentrations are given for plasma and erythrocytes from four unaffected relatives of patients with X-linked ichthyosis, a patient with placental sulfatase deficiency, two patients with other types of ichthyoses, and 20 controls. The method may also be of use for the rapid isolation of other organic sulfates from biological material, as illustrated by a comparison of gas chromatograms of urine from a normal pregnant woman and that from a patient with placental sulfatase deficiency.
A macro creatine kinase isoenzyme in serum of apparently healthy individuals.
Authors: Whelan P V , Malkus H 
Published: January 2020

Abstract
Activity of creatine kinase B subunit, as measured by an immunoinhibition assay, is persistently increased in certain healthy, asymptomatic adults, whose values for total CK activity are within normal limits. Serum samples from two such individuals were investigated by electrophoresis, heat inactivation, determination of activation energies, and immunosorption (on protein A). The results demonstrated the presence of a circulating complex of IgG and CK-BB, which has been described as macro CK, type I. To our knowledge, this is the first report of such macro CK isoenzymes in healthy individuals.
Liquid-chromatographic assay of cefmenoxime in serum and urine.
Authors: Reitberg D P , Schentag J J 
Published: January 2020

Abstract
This is a simple, precise liquid-chromatographic procedure for determining cefmenoxime in patients' serum and urine. p-Anisic acid is used as the internal standard. Protein is precipitated from 0.5 mL of serum or dilute urine with 100 microL of perchloric acid. The clear supernate is injected directly onto a mu-Bondapak CN reversed-phase column. The mobile phase is acetate buffer, pH 3.8 (25 degrees C). The flow rate is 2.5 mL/min. Column effluent is monitored at 254 nm. Extraction recovery from serum averaged 74.6%. Calibration curves were linear from 0.5 mg/L, the lower limit of quantification, to 100 mg/L. We present cefmenoxime concentrations in serum from a patient being treated for pneumonia. The procedure was evaluated in the clinical setting to determine its applicability to the study of cefmenoxime pharmacokinetics in critically ill patients.
The Kodak Ektachem 400 Analyzer evaluated for automated enzymic determination of plasma creatinine.
Authors: Smith C H , Landt M , Steelman M , Ladenson J H 
Published: January 2020

Abstract
We have evaluated an automated creatinine iminohydrolase procedure for plasma creatinine analysis, as used in the Kodak Ektachem 400 Analyzer. The correlation with kinetic and end-point (equilibrium) alkaline picrate procedures is generally excellent. The enzymatic procedure has the advantage of being unaffected by bilirubin, cephalosporins, and acetoacetate, all of which interfere in alkaline picrate procedures. Its accuracy, however, greatly depends on calibration values provided by the manufacturer. Storage of samples at -20 degrees C produced little change in measured creatinine. The Ektachem procedure has a greater range of linearity (140 mg/L) than the alkaline picrate procedures, but it shares with them the disadvantages of suboptimal precision in the normal range. The increased specificity, ease of performance, and other advantages of this use of creatinine iminohydrolase make it an attractive procedure.
Densitometry of phosphatidylcholine and sphingomyelin in high-density lipoproteins.
Authors: Schmitz G , Jabs H U , Assmann G 
Published: January 2020

Abstract
We describe the quantitative densitometric determination of phosphatidylcholine (PC) and sphingomyelin (SP) in human serum after precipitation with phosphotungstic acid/MgCl2 and use of thin-layer chromatography. After development, chromatographic plates were charred with methanolic sulfuric acid and MnCl2 and scanned by direct reflectance densitometry in an automated densitometric system interfaced to a basic programmable computing integrator. The method is sensitive enough to detect abnormally low concentrations of PC and SP in high-density lipoproteins. The accuracy of the method was tested either with the Bartlett phosphorus assay or with enzymatic methods for PC and SP; correlations of the described method with the enzymatic determinations were r = 0.93 and 0.88, respectively. Day-to-day precision (CV) for the phospholipid determination was 8.6% for PC and 12.2% for SP. The major advantage of this inexpensive technique is that native plasma or serum or the serum supernate after precipitation can be used without prior delipidation. With this technique serum high-density lipoproteins had PC values of 1.08 (SD 0.32) mmol/L in men (n = 158) and 1.12 (SD 0.37) mmol/L in women (n = 192); similarly, SP values were 0.23 (SD 0.07) mmol/L in the men and 0.23 (SD 0.08) mmol/L in the women. The differences by sex are not significant.
Heterogeneity of lipoprotein electrophoretic patterns in patients with type IIa hyperlipoproteinemia.
Authors: Hoeg J M , Papadopoulos N M , Gregg R E , Brewer H B 
Published: January 2020

Abstract
Previous evaluations of plasma lipoproteins from patients with type IIa hyperlipoproteinemia have demonstrated quantitative but not qualitative differences from lipoproteins isolated from normal subjects. Using a reproducible, sensitive, high-resolution agarose gel electrophoretic system, we evaluated the plasma lipoprotein of 22 consecutive, untreated, unrelated patients with type IIa hyperlipoproteinemia. Five distinct electrophoretic patterns were observed. This electrophoretic heterogeneity in type IIa hyperlipoproteinemia reflects subtle charge differences in the lipoproteins from these patients, which were not detected with paper electrophoresis or with lipoprotein quantification. There was little, if any, difference in total plasma cholesterol, low- or very-low-density lipoproteins, plasma triglycerides, or concentrations of apolipoproteins A-I, A-II, B, C-II, or E in these subgroups. However, unique clinical features were correlated with the electrophoretic patterns. These findings support the concept that the type IIa hyperlipoproteinemic phenotype includes several molecular defects that are reflected in subtle differences in lipoprotein charge.
Acridinium esters as high-specific-activity labels in immunoassay.
Authors: Weeks I , Beheshti I , McCapra F , Campbell A K , Woodhead J S 
Published: January 2020

Abstract
A chemiluminescent acridinium ester has been synthesized that reacts spontaneously with proteins to yield stable, immunoreactive derivatives of high specific activity. The compound has been used to prepare chemiluminescent monoclonal antibodies to human alpha 1-fetoprotein having average incorporation ratios as great as 2.8 mol of label per mole of antibody, which corresponds to a detection limit of approximately 8 X 10(-19) mol. These antibodies have been used in the preliminary development of a two-site immunochemiluminometric assay for human alpha 1-fetoprotein, which requires only a 30-min incubation and a quantification time of 5 s per sample.
Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.
Authors: McGowan M W , Artiss J D , Zak B 
Published: January 2020

Abstract
A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.
Micromethod for determination of lactate dehydrogenase isoenzyme C4 activity in human seminal plasma.
Authors: Butrimovitz G P , Farina F , Sharlip I 
Published: January 2020

Abstract
We have developed an automated enzymatic assay for LDH-C4, a lactate dehydrogenase (EC 1.1.1.27) isoenzyme found exclusively in spermatozoa, as a marker of human spermatogenesis. LDH-C4 activity is assayed bichromatically in the Abbott ABA-100 spectrophotometer, with 2-oxohexanoate as substrate. As many as 27 samples (2.5 microL) of human seminal plasma can be analyzed sequentially, with apparent zero-order kinetic conditions and with a precision (CV) of 5%. The apparent Km for the 2-oxohexanoate reaction is 11.2 mmol/L. Electrophoretic and enzymatic studies indicate that LDH-C4 acts on this substrate to produce hydroxyhexanoate, in contrast to lactate dehydrogenase isoenzymes 1 and 5--further evidence for the uniqueness of LDH-C4. The sensitivity, specificity, and speed of this assay system makes it practicable for studies on, and evaluation of, male fertility.
Viscosity adaption for an automated micromethod of flame atomic absorption spectrometry, and intracellular trace-element analysis after pressure decomposition: zinc determination in plasma and erythrocytes.
Authors: Sprenger K B , Franz H E 
Published: January 2020

Abstract
We measured zinc in the plasma of 50 normal persons, and in erythrocytes of six, by an automated micromethod of atomic absorption spectrometry. Using a rotation viscometer, we measured the viscosity and flow behavior of plasma, undiluted and equi-volume diluted (with water), from 12 patients, and, for comparison, of two- to 20-fold dilutions of an 870 mL/L glycerol solution. Erythrocytes were washed three times, lyophilized, and wet-ashed in a pressure decomposition device. The mean viscosity of equi-volume diluted plasma is about the same as that of the glycerol solution diluted 7.5-fold. The observed concentration of zinc in normal plasma was 13.8 (SD 1.9) mumol/L, with intra-assay CV (n = 30) of 2%, day-to-day CV (n = 22) 3.8%, and accuracy (measurement of an aqueous std.) 2.5%. The mean normal value for erythrocyte zinc was 34.7 micrograms/g, with intra-assay CV (n = 8) 5%, day-to-day CV (n = 6) 5.9%, and accuracy 4.6%. Our results compare well with those by neutron activation analysis, the differences in values being 3% for plasma, 1% for erythrocytes.
Test-request patterns for clinical chemistry in a British and a Canadian renal dialysis unit.
Authors: Gardner M D , Henderson A R 
Published: January 2020

Abstract
We recorded, during four months, the total number of routine clinical chemistry tests requested for patients with end-stage renal failure who were on regular maintenance hemodialysis during the study: 20 in the Renal Dialysis Unit of a British and 20 in a Canadian teaching hospital. The pattern of tests ordered was substantially the same in each unit, but the frequency of testing was not. The total number of tests (and tests per patient per month) was 1616 (20.2) for the British and 6939 (86.7) for the Canadian unit (significant at p less than 0.001). This study suggests a significant difference between the two countries in the utilization of laboratory services, and supports our earlier findings on total clinical chemical workloads in hospitals.
Simplified methods for measuring enzyme kinetics in a single cell.
Authors: Marković N S , Marković O T , Young D S 
Published: January 2020

Abstract
We discuss techniques for measuring myeloperoxidase activity cytochemically in isolated polymorphonuclear neutrophils. We have used a sophisticated scanning microdensitometer as a reference device and compared results obtained by Zeiss Ultraphot III B and Reichert Zetopan microscopes with those of the scanning microdensitometer. We made both end-point and kinetic measurements, using conventional microscope slides and a special incubation chamber. Some resolution is lost with simpler microscope systems, but they provided results sufficiently like those obtained with the scanning microdensitometer that they could be used in the clinical laboratory to allow investigation of enzyme activity in single cells.