bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sampling and analysis techniques used in a blood lead survey of 1241 children in Port Pirie, South Australia.
Authors: Sinclair D F , Dohnt B R 
Published: January 2020

Abstract
Methods are described for taking finger-prick blood samples and for analyzing these samples for lead. Quality-control techniques and procedures for the validation of all results are described. Results of a survey of 1241 children are given and results for 149 venous samples are compared with results for the corresponding finger-prick samples. This finger-prick sampling method evidently is suitable for use in screening large numbers of children.
Reaction of picrate with creatinine and cepha antibiotics.
Authors: Kroll M H , Hagengruber C , Elin R J 
Published: January 2020

Abstract
The concentration of creatinine in serum, which is used to estimate glomerular filtration rate, is measured by reaction with alkaline picrate, but this reaction is not specific for creatinine. Although several other cephalosporin antibiotics have been reported not to react with picrate, we reacted picrate with creatinine, cefoxitin, penicillin, and eight different cephalosporins, and found that all compounds reacted with picrate and showed superimposable spectrophotograms with absorption maxima at 485 nm. From these results we conclude that the color-absorbing moiety of the product is the picrate molecule. Further, the structure common to creatinine and the cephalosporins, cefoxitin, or penicillin is the carbonyl group attached to a nitrogen and a carbon atom. We postulate that the carbonyl group with the adjacent carbon and nitrogen atoms is probably the chemical moiety that reacts with picrate to absorb energy at 485 nm.
Simple colorimetry of glycated serum protein in a centrifugal analyzer.
Authors: Lloyd D , Marples J 
Published: January 2020

Abstract
A recently described (Clin Chim Acta 127: 87-95, 1982) colorimetric assay for glycated proteins in serum exploits their ketoamine activity to reduce 3,3'-(3,3'-dimethoxy-4,4'-biphenylylene)bis [2-(p-nitrophenyl)-5-phenyl-2H-tetrazolium chloride] (nitroblue tetrazolium) in alkaline solution; the authors termed this the "fructosamine assay." The method is simple, requiring only the addition of one reagent and measurement of the absorbance change during 5 min; results are expressed relative to a synthetic standard. We have adapted this for use in a centrifugal analyzer and report its performance, both analytically and as an index of hyperglycemia. Precision is good (between-batch CV 2.1%), the reagent is stable and inexpensive, and the procedure is rapid (75 samples per hour). Albumin influences the measurement, but for concentrations greater than or equal to 35 g/L this was not a serious problem. Normal and diabetic populations can be clearly discriminated (p less than 0.001). The test detected 25 (84%) of the 30 untreated diabetics studied and gave four false positives (8%). The results correlate well with those for glucose in plasma of fasting subjects (r = 0.87) and for hemoglobin A1 (r = 0.80).
A rapid silver-stain procedure for use with routine electrophoresis of cerebrospinal fluid on agarose gels.
Authors: Lubahn D B , Silverman L M 
Published: January 2020

Abstract
Oligoclonal banding patterns, when present in cerebrospinal fluid (CSF) electrophoresed on agarose gels, are important in the diagnosis of multiple sclerosis and other demyelinating diseases. Typically, an 80-fold concentration of 2.5 mL of CSF has been needed before the oligoclonal banding pattern could be detected with Coomassie Brilliant Blue stain. This excessive volume requirement often is a problem, particularly in children. We describe here an improved silver-stain procedure with which we routinely can detect the oligoclonal banding pattern in 1 to 3 microL of unconcentrated CSF. The procedure is inexpensive and takes less than 45 min. Our method is quick, safe, sensitive, and easily performed in the clinical laboratory.
Modified radioassay for measuring asialoglycoprotein in serum.
Authors: Byrn R , Thomas P , Medrek P , Spigelman Z , Zamcheck N 
Published: January 2020

Abstract
Asialoglycoproteins are removed from the circulation by the carbohydrate-specific hepatic binding protein in the rat. Asialoglycoprotein in human serum can be detected by an inhibition assay in which the binding of 125I-labeled asialo-alpha 1-acid glycoprotein (ASAG) to purified hepatocyte membranes is inhibited by known amounts of ASAG or patient's serum. We were able to reproducibly measure inhibition equivalent to that of 1 to 20 ng of ASAG. The mean concentration of inhibitor in 11 healthy control patients was equivalent to 0.153 (SD = 0.051) mg of ASAG per liter, measured in 20 microL of serum. Significant increases of inhibitor were observed in patients with malignant extrahepatic biliary obstruction, alcoholic liver disease, viral hepatitis, or liver metastases, but not in those with benign biliary obstruction. For a set of six control sera the intra- and interassay CVs were 9.1% and 25.2%, respectively (n = 3 each).
Analyses for progesterone in serum by gas chromatography/mass spectrometry: target data for external quality assessment of routine assays.
Authors: Gaskell S J , Brownsey B G , Groom G V 
Published: January 2020

Abstract
We describe a procedure for measuring progesterone in plasma and serum by isotope dilution and mass spectrometry. Extraction with use of a microcellulose-coupled antiserum is followed by conversion to the 3-enol heptafluorobutyrate and analysis by gas chromatography/mass spectrometry (GC/MS) with selected ion monitoring, at a resolution of 5000. Interassay CVs were 1.5 to 5.4% for the concentration range 13 to 43 nmol/L. Analyses of various serum volumes showed excellent linearity. Accurate determination of progesterone added to serum was demonstrated. Plasma and serum pools were analyzed to provide target data for use in the U.K. national external quality-assessment scheme for progesterone assays. Direct, non-extraction radioimmunoassays and those incorporating solvent extraction both showed a positive bias with respect to data obtained by the present procedure, but the bias was more marked with the direct assays.
Vanadium in human serum, as determined by neutron activation analysis.
Authors: Simonoff M , Llabador Y , Peers A M , Simonoff G N 
Published: January 2020

Abstract
Vanadium concentrations have been measured in the serum of 23 healthy subjects by neutron activation analysis, with post-irradiation chemical separation. The values obtained fall in a fairly narrow range (260-1300 ng/L, mean 670 ng/L), which suggests a physiological role for this element. We checked the method by analysis of standard (U.S. National Bureau of Standards) water samples and serum samples supplemented with 48V, and we found excellent agreement with expected results in both cases. We consider the reported results for human serum to be more reliable than those obtained by atomic absorption spectroscopy.
Calculated vs measured plasma osmolalities revisited.
Authors: Bhagat C I , Garcia-Webb P , Fletcher E , Beilby J P 
Published: January 2020

Abstract
The osmolalities of 100 plasma samples were measured and compared with the osmolalities calculated from the plasma concentrations (mmol/L) of sodium, potassium, glucose, and urea by several different formulae. The formula recommended by Dorwart and Chalmers (Clin Chem 21: 190, 1975) gave inferior results to those obtained with our "most accurate" formula: osmolality = 1.89 Na + 1.38 K + 1.03 urea + 1.08 glucose + 7.45. We recommend using this formula for calculation of osmolality on equipment linked to a computer. However, for simplicity, and to reduce the possibility of calculation errors, the following formula can be used for manual calculations: osmolality = 1.86 (Na + K) + glucose + urea + 10.
The Quantab strip in the measurement of urinary chloride and sodium concentrations.
Authors: Sloan P J , Beevers G , Baxter F E 
Published: January 2020

Abstract
The "Quantab" strip (Ames) measures chloride in fluids. For sodium chloride solutions and urine we found very good correlations between the Quantab reading and the chloride concentration as measured by chemical assay (r = 0.95 for chloride and r = 0.85 for sodium in urine). The strip gave reproducible results over the temperature range 4 to 37 degrees C. There was very little inter- and intra-observer variation in reading the strip. Although 10 to 23 min is required to complete the reaction, the strip reading is stable thereafter. We suggest that the strip could be useful in epidemiological studies of urinary sodium concentration and clinically in helping patients adhere to a low-salt diet.
Two direct (nonchromatographic) assays for 25-hydroxyvitamin D.
Authors: Bouillon R , Van Herck E , Jans I , Tan B K , Van Baelen H , De Moor P 
Published: January 2020

Abstract
We describe direct, nonchromatographic assays for 25-hydroxyvitamin D3 in which we use either rat vitamin D-binding protein or rabbit antibodies to 25-hydroxyvitamin D3-3-hemisuccinate-bovine serum albumin as binding protein. Nonspecific interferences in serum could be eliminated by an appropriate extraction method or in obtaining data for the calibration curve, by using vitamin D-free human serum. The latter is prepared by affinity chromatography with use of immobilized antibodies against human vitamin D-binding protein. Values obtained by the direct assays and those obtained by two different chromatographic methods correlated well (r greater than 0.95). The direct competitive protein-binding assay overestimated the true 25-hydroxyvitamin D3 concentration by about 20%, but this percentage was constant from 5 to 600 micrograms/L. Overestimation by the direct radioimmunoassay was less than 10%. These two direct assays for 25-hydroxyvitamin D3 allow reliable, rapid, and simple screening for vitamin D deficiency or excess.
Biological variance of total lactate dehydrogenase and its isoenzymes in human serum.
Authors: Moses G C , Henderson A R 
Published: January 2020

Abstract
We measured the variance components of total lactate dehydrogenase (LD; EC 1.1.1.27) activity and isoenzymes in sera of 24 healthy laboratory staff, ages 23-50 years, over a 12-month period. We used the first six weeks' results to establish baseline values for each analyte in each individual. These values were "normally" distributed for total LD and isoenzymes 1 through 4, but values for isoenzyme-5 were skewed slightly to the left. The overall means and variances determined for the remaining 10 months were not significantly (p greater than 0.05) different from the corresponding baseline values. Average variances (SD2) for the longer-term (10-month) study were: intra-individual, 732, 1.92, 2.25, 1.09, 1.11, and 2.25, and inter-individual, 1988, 5.03, 1.76, 1.57, 1.21, and 2.01 for total LD (U/L) and LD-1 through LD-5 (% of total), respectively. Average long-term analytical variability was less than 35% of the total variance for the five isoenzymes and 6% for total LD, and was characteristic of the individual. There were no significant differences in mean activities with respect to age or sex. All six analytes exhibited slight seasonal variations.
An automated "high-pressure" liquid-chromatographic assay for hemoglobin A1c.
Authors: Ellis G , Diamandis E P , Giesbrecht E E , Daneman D , Allen L C 
Published: January 2020

Abstract
An automated "high-pressure" liquid-chromatographic assay for hemoglobin A1c is described. We use a 45-min incubation in acetate buffer (pH 5.5) to eliminate labile glycated hemoglobins. In this automated system conventional modules are used but it incorporates a solvent-switching valve to select either of two buffers, which differ in pH and NaCl concentration. The chromatographic column contains "polyCAT" (a weak cation-exchanger, polyaspartic acid linked to silica). Run time is 14 min per sample. The method is precise and results correlate well with those by other ion-exchange procedures.
New photometric assay for chymotrypsin in stool.
Authors: Kaspar P , Möller G , Wahlefeld A 
Published: January 2020

Abstract
In this new photometric assay fecal samples are pretreated with detergent and high concentrations of salts. The subsequent kinetic enzyme determination step involves the chromogenic substrate succinyl-Ala-Ala-Pro-Phe-4-nitroanilide. The sample pretreatment assures a nearly complete solubilization of the formerly particle-bound enzyme, thus permitting determination of the enzyme activity in either the suspension or the supernate after centrifugation. Furthermore this pretreatment enhances the enzyme activity and decreases the Km value. Results by this assay correlate well with those by classical titrimetry and the method is easily adapted to automated systems.
Kinetic approach for the enzymic determination of creatinine.
Authors: Perakis N , Wolff C M 
Published: January 2020

Abstract
By exploiting the kinetics of NADH consumption in the enzyme system creatinine amidohydrolase + creatine kinase + pyruvate kinase + lactate dehydrogenase, one can determine creatinine in serum in the range of 1 to 90 mg/L. By using the conditions defined here, this determination can be made with a single measurement of the rate of disappearance of NADH. The analytical rate measurement is made at a fixed time (2 min) after the sample is introduced into the enzyme solution. For this fixed time, the interferences of creatine and pyruvate are eliminated. Results so obtained for creatinine in human blood serum samples correlated well (r = 0.98) with those obtained by the classical Jaffé-reaction method. Run-to-run reproducibility (CV) was 3%, and the limit of detection was 1 mg/L.
Five methods for determining low-density lipoprotein cholesterol compared.
Authors: Demacker P N , Hijmans A G , Brenninkmeijer B J , Jansen A P , van 't Laar A 
Published: January 2020

Abstract
We evaluated three precipitation methods for determination of low-density lipoprotein cholesterol in serum and an indirect method involving the Friedewald formula (Clin Chem 18: 499-502, 1972) by comparison with results by ultracentrifugation. The results of all methods for 83 sera, including 59 hyperlipidemic type IIA, IIB, and IV sera agreed very well, at least for concentrations of serum triglycerides below 8 mmol/L. The accuracy of the Friedewald formula was confirmed in 285 other sera, including 66 sera with triglycerides content between 4.52 and 8.0 mmol/L. For type III sera, the precipitation methods produced similar values to those obtained with the Friedewald formula, all being much higher than the ultracentrifugation values. Density-gradient ultracentrifugation showed that the very-low-density lipoprotein remnants in type III sera almost completely coprecipitated with the low-density lipoproteins. The precipitation methods are not only accurate but also very precise (CV less than 5%); they can therefore be used in clinical laboratories to measure atherogenic low-density lipoproteins plus the remnants of very-low-density lipoproteins. However, when serum triglycerides and high-density lipoprotein cholesterol also are determined, the Friedewald formula is a reliable alternative.
Unreliability of immunochemical determination of lactate dehydrogenase isoenzyme-1 in heparinized plasma.
Authors: Lum G 
Published: January 2020

Abstract
Paired serum and heparinized plasma samples were assayed simultaneously for lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 (LD1) activity by a commercially available immunochemical procedure. For all sera specimens tested, only LD1 activity was detected. For heparinized plasma, random discrepancies in LD1 activity were noted at normal (Group I), borderline (Group II), and increased (Group III) total LD activity. Incomplete precipitation of LD-M subunits was confirmed by electrophoresis and occurred in eight of 15, four of 13, and eight of 22 instances (total: 20/50, or 40%) with a mean difference of 13, 10.6, and 18.2 U/L (8.3, 4.0, and 4.4%) in Groups I, II, and III, respectively. We conclude that heparinized plasma is an unsuitable sample for the immunochemical determination of LD1.
Inadequate hemolysis of erythrocytes on reagent strips at low pH causes false-negative readings.
Authors: Levin K , Engström I 
Published: January 2020

Abstract
Patients' urines gave an unexpectedly high percentage of false-negative results for erythrocytes on a reagent strip, even when the test field for ascorbic acid indicated that none of this substance was present to inhibit the test reaction. By adding known amounts of erythrocytes to normal urines, we found that this phenomenon was time-dependent and occurred with three different brands of reagent strips in urines having a pH below 6.0. Hemolysis of erythrocytes was totally inhibited below pH 5.1 after 4 h of incubation with 50 X 10(6) erythrocytes per liter. The inhibition is apparently caused by shrinkage of the erythrocytes, rending them insensitive to the hemolytic agents in the different reagent strips tested.
Identification of polypeptides on two-dimensional electrophoresis gels by amino acid composition.
Authors: Latter G I , Burbeck S , Fleming J , Leavitt J 
Published: January 2020

Abstract
We present a method that can, in principle, provide tentative identification of a substantial proportion of the polypeptides resolvable on a given two-dimensional electrophoresis gel. Computerized microdensitometry of autoradiograms from 20 gels labeled in turn with each of the 20 common amino acids provides the data for simultaneously measuring the amino acid composition of all polypeptides of interest on the gel. These compositions are then compared with computer data bases of known protein compositions. Similarity between a known and an unknown polypeptide with comparable molecular mass indicates a potential identification, which can then be confirmed with conventional techniques. We illustrate this technique by applying it to the identification of proteins in a transformed human cell line (HuT-14).
"Ultrasensitive" silver stains: their use exemplified in the study of normal human cerebrospinal fluid proteins separated by two-dimensional electrophoresis.
Authors: Merril C R , Harrington M G 
Published: January 2020

Abstract
We have developed a series of photochemical silver stains that are more than 100 times as sensitive as the Coomassie Blue stains. These stains facilitate the quantitative estimation of proteins in two-dimensional gel patterns. Recently, we discovered that by using light (photodevelopment) to catalyze the reduction of ionic silver to metallic silver, we could produce an image of proteins on polyacrylamide gels within 10 min after their electrophoretic separation. We used these stains to detect proteins resolved in two-dimensional electrophoretograms of lumbar cerebrospinal fluid from 51 normal human volunteers, finding no qualitative protein changes in the more than 300 CSF polypeptides resolved on each individual's electrophoretogram. We quantified 67 of these proteins per individual with computer-assisted densitometry, only five of which showed significant quantitative age-related alterations. We saw no sex-related differences. This consistency in the protein pattern for cerebrospinal fluid from normal individuals allows it to serve as a baseline for comparisons with disease states.
Two-dimensional electrophoresis of proteins in human serum: improved resolution by use of narrow pH gradients and prolonged electrophoresis.
Authors: Marshall T , Williams K M , Vesterberg O 
Published: January 2020

Abstract
The limited resolution of serum proteins achieved with a simplified technique of two-dimensional electrophoresis (Clin. Chim. Acta 103: 51-59, 1980) has been improved by using different ampholyte (Ampholine) mixtures in the first dimension, to obtain relatively shallow pH gradients, and prolonged electrophoresis time in the second dimension. The technique has been further simplified, without negative effect, by decreasing the concentration of non-ionic detergent (first dimension), omitting both sodium dodecyl sulfate equilibration and the use of a stacking gel (second dimension), and by using an improved silver-staining procedure. Reverse-polarity isoelectric focusing and non-equilibrium pH-gradient electrophoresis have been successfully used to resolve the basic polypeptides in serum after deleting sodium dodecyl sulfate from the sample preparation. These combined techniques reveal over 1100 polypeptides in human serum. After immunodeletion of albumin, additional serum polypeptides are seen. Immunodeletion of serum proteins from plasma reveals polypeptides that are relatively specific to plasma.
Changes in the expression of hepatocyte protein gene-products associated with adaptation of cells to primary culture.
Authors: Colbert R A , Amatruda J M , Young D A 
Published: January 2020

Abstract
Expression of hepatocyte protein gene-products changes as cells adapt to the environment of tissue culture. We examined such changes, using "giant" two-dimensional (2-D) gel electrophoresis. Over 80 cellular and secreted proteins, about 3% of the 2500 we examined, were found to change spontaneously during the 20-h culture period. The magnitude of these changes was estimated to range from 1.5- to nearly 100-fold. If dexamethasone is included in the culture medium, the overall production of secreted proteins is maintained, but in addition it exerts major influences on the expression of individual protein gene-products. Ten of the spontaneous changes are enhanced and eight are unaffected, but most are substantially retarded (32) or even reversed (27). There are also large inductions or repressions in 12 proteins that do not change spontaneously in culture. We have tentatively identified tyrosine aminotransferase, phosphoenolpyruvate carboxykinase, gamma-fibrinogen, and alpha 1-acid glycoprotein to be among those induced by dexamethasone. Evidently, many more changes occur as these cells adapt to tissue culture than was previously appreciated. These results emphasize the power of 2-D gel analysis in monitoring the protein phenotype of cells. We have also shown that glucocorticoids are important in maintaining the overall synthesis of secreted proteins and the protein phenotype of isolated hepatocytes in primary culture.
Leukocyte membrane proteins in chronic lymphocytic leukemia, as studied by two-dimensional gel electrophoresis.
Authors: Willard-Gallo K E , Humblet Y , Symann M 
Published: January 2020

Abstract
We evaluated protein expression in leukocytes from 20 patients with chronic lymphocytic leukemia (CLL), including one with the rare T-cell form of the disease. To identify proteins that potentially could be used to characterize leukemia or as candidates for new markers of differentiation, we studied cell and membrane extracts from these leukemic cells. We used immune precipitation and extraction of integral membrane proteins with Triton X-114 to identify known proteins on the surface of these cells. Extraction with Triton X-114 in the presence of protease inhibitors yielded reproducible membrane extracts, which we examined by two-dimensional gel electrophoresis. Of the approximately 2000 proteins or protein subunits so resolved from cell lysates and the 450 from membrane extracts of leukocytes from patients with T- and B-cell CLL, we were able to identify spots corresponding to the proteins designated by the OKT.4 and OKT.10 antibodies, the human class I and II histocompatibility antigens, beta 2-microglobulin, and surface IgM. We also defined sets of proteins that are characteristically expressed on the membranes of leukemic T or B cells, some of which correspond to previously defined markers of normal leukocyte subpopulations.