bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assay of delta-aminolaevulinate dehydratase in 10 microL of blood.
Authors: Wigfield D C , Farant J P 
Published: January 2020

Abstract
A method is presented for the assay of delta-aminolaevulinate dehydratase (EC 4.2.1.24) to be performed on 10 microL of whole blood. Results compare favorably with those obtained with an accepted method (J. Clin. Chem. Clin. Bio-chem. 12: 389-390, 1974) that involves use of 200 microL of blood.
Colorimetric vs liquid-chromatographic determination of urinary 5-hydroxyindole-3-acetic acid.
Authors: Tracy R P , Wold L E , Jones J D , Burritt M F 
Published: January 2020

Abstract
The popular colorimetric assay for urinary 5-hydroxyindole-3-acetic acid based on the reaction with 1-nitroso-2-naphthol has been criticized for lack of specificity. Goldenberg (Clin. Chem. 19: 38-44, 1973) proposed a modification of this method, in which 2-mercaptoethanol is used to discharge unwanted chromophores. We compared results by both the unmodified and modified colorimetric methods with those by a "high-performance" liquid-chromatographic method, with fluorometric detection. Agreement among all three assays was excellent in the range of 50 to 600 mg/24 h, but there were considerable differences in the range 0 to 30 mg/24 h between results by the unmodified colorimetric assay and the other two. In this range, results by the modified assay (y) correlated well with those by the chromatographic method (x), although the values were slightly lower (y = 0.85x + 0.11, r = 0.9303). Using the modified colorimetric assay to analyze 40 normal specimens, we defined a normal range of 0 to 6 mg/24 h). We recommend the modified colorimetric assay for use in the high-volume laboratory and either this assay or the liquid-chromatographic method for the smaller laboratory.
Measurement of serum lipase activity with the oxygen electrode.
Authors: Griebel R J , Knoblock E C , Koch T R 
Published: January 2020

Abstract
We describe the measurement of lipase (triacylglycerol lipase; EC 3.1.1.3) in serum by continuous monitoring of relative rates of oxygen consumption with a polarographic oxygen electrode. The reactions described by Proelss and Wright (Clin. Chem. 23: 522-531, 1977) are used: trilinolein, with lipase catalysis, yields linoleic acid, which reacts with oxygen in the presence of lipoxygenase. Lipase activity is measured by comparing the zero order reaction rate of the specimen with that obtained with linoleic acid standards. Results for lipase (y) correlated well with those by the copper-soap method of Myrtle and Zell (x) (Clin. Chem. 21: 1469-1473, 1975); y = 0.33x - 11; r = 0.98; n = 34. Results are unaffected by specimen dilution, and the standard curve is linear to 520 U/L. Day-to-day precision (CV) is 10.4% for normal activities, 6.1% for above-normal activities. We believe the method offers a precise, practical approach to lipase analysis.
Combined enzymic-Jaffé method for determination of creatinine in serum.
Authors: Masson P , Ohlsson P , Björkhem I 
Published: January 2020

Abstract
Concentrations of creatinine, as determined in serum by a method involving the combined use of creatinine amidohydrolase (EC 3.5.2.10) and alkaline sodium picrate were found to be factitiously low, owing to a reversal of the enzyme reaction. This effect could be eliminated by converting creatine, the product of the enzymic reaction, to creatine phosphate. The combined enzymic-Jaffé method was therefore modified to include creatine amidohydrolase, creatine kinase, ATP, and Mg2+ in the reaction mixture. The modified method has good precision. We saw no significant interferences by relatively high concentrations of acetone, acetylacetone, ADP, creatine, creatine phosphate, glucose, glycocyamine, or pyruvate. Likewise, no interferences were evident with icteric, lipemic, or hemolytic serum samples. There was an excellent agreement between creatinine values obtained with our method and by a reference method based on isotope dilution-mass fragmentography. Our method is considerably simpler than the fully enzymic method for determination of creatinine and might be a method of choice if a high accuracy is desired.
Creatine kinase B-subunit activity in human sera: temporal aspects of its sensitivity after myocardial infarction.
Authors: Elser R C , McKenna K 
Published: January 2020

Abstract
We assessed the changes in sensitivity and specificity of creatine kinase (CK) isoenzymes at various times after acute myocardial infarction. CK-B was measured by an immunoinhibition technique. CK-MB was measured both by column chromatography on Sephadex DEAE A-50 and by electrophoresis on agarose gel. For CK-B, the sensitivity in detecting infarct varied from 11% in the first 8 h after onset of symptoms to 80% at 32 h after the infarct. Sensitivities for CK-MB by column and by electrophoresis were 25 and 45% for the first 8-h period and 80 and 89% at the 32nd hour, respectively. Comparison of values for CK-B with values for CK-MB by column and by electrophoresis gave correlation coefficients of 0.935 and 0.896, respectively. Patients having macro CK-BB exhibit anomalously high values for CK-B with respect to total CK. Patients having a mild infarct may show no increase in CK-isoenzymes.
Purification of lactate dehydrogenase isoenzyme-5 from human liver.
Authors: Pettit S M , Nealon D A , Henderson A R 
Published: January 2020

Abstract
We present a method for preparing human liver lactate dehydrogenase (L-lactate:NAD+ oxidoreductase; EC 1.1.1.27) isoenzyme-5 by sequential ion-exchange chromatography, general-ligand (AMP analog) affinity chromatography, and preparative isoelectric focusing. The yield ws 40%, with a 493-fold purification. The final specific activity was 458 kU per gram of protein. The preparation contained less than 0.2% of lactate dehydrogenase isoenzyme-4, was homogeneous by agarose gel electrophoresis and also by polyacrylamide gel electrophoresis at pH 8.9 and 6.9, and showed one major protein band (containing all the enzyme activity) and one minor anodic contaminant (containing no enzyme activity) by analytical isoelectric focusing. The enzyme had a mean pI value of 9.59 (SD 0.04) (n = 5) at 5 degrees C. By comparison, the pI value of a preparation of rabbit lactate dehydrogenase-5 was 9.16 (5 degrees C).
A candidate reference method for determination of total protein in serum. I. Development and validation.
Authors: Doumas B T , Bayse D D , Carter R J , Peters T , Schaffer R 
Published: January 2020

Abstract
We developed a candidate Reference Method for measuring total serum protein by use of the biuret reaction. The method involves a previously described biuret reagent (Clin. Chem. 21: 1159, 1975) and Standard Reference Material (SRM) 927 bovine albumin (National Bureau of Standards) as the standard. At 25 degrees C, color development for 30 or 60 min provides identical serum protein values. Glucose (up to 10 g/L) and bilirubin (up to 300 mg/L) do not interfere. Hemoglobin, at 3 g/L, increases apparent serum protein by 0.4 g/L. The presence of dextran in serum causes easily detected turbidity, but this interference can be eliminated by centrifuging the reaction mixture. Therapeutic concentrations of ampicillin, carbenicillin, penicillin, oxacillin, nafcillin, chloramphenicol, cephalothin, and methicillin in blood do not interfere, nor do triglycerides up to 10 g/L. Within-run and day-to-day standard deviations of the method are 0.1 and 0.4 g/L, respectively.
Immunoreactive trypsin and pancreatic isoamylase activity in serum of patients with chronic renal failure or hepatic cirrhosis.
Authors: Fahrenkrug J , Staun-Olsen P , Magid E 
Published: January 2020

Abstract
In 121 patients with either liver cirrhosis or chronic renal failure, abnormal values for the concentrations of two pancreatic enzymes in serum were a frequent finding. In renal insufficiency a decreased rate of enzyme elimination is the most likely cause of the above-normal values we observed for serum immunoreactive trypsin and pancreatic isoamylase activity. As for patients with liver cirrhosis, we believe that changes in entrance rates into the blood--i.e., an affected pancreas--is a likely explanation of the abnormally high values we often found for these serum enzymes.
[14C]Oxalate absorption by normal persons, calcium oxalate stone formers, and patients with surgically disturbed intestinal function.
Authors: Tiselius H G , Ahlstrand C , Lundström B , Nilsson M A 
Published: January 2020

Abstract
Intestinal absorption of oxalate can be judged from the urinary excretion of orally administered [14C]oxalate. Fifteen normal subjects, 21 patients with "idiopathic" calcium oxalate stone disease and a high oxalate excretion, four patients operated with ileocecal resection, and seven patients operated with jejunoileal bypass were so investigated. We saw no significant difference in the amount of isotope excreted by normal subjects and idiopathic stone formers; 13.6% (SD 5.9%) and 14.4% (SD 6.5%), respectively, of the administered dose was accounted for in the urine. The patients with resection or bypass showed a quite different pattern of isotope excretion, and 18.3% (SD 7.0%) and 36.8% (SD 14.0%), respectively, of the isotope was accounted for in the urine.
Monoclonal antibodies in clinical immunology.
Authors: Sevier E D , David G S , Martinis J , Desmond W J , Bartholomew R M , Wang R 
Published: January 2020

Abstract
Advances in clinical immunodiagnostics resulting from the application of hybridoma technology are starting to appear. Monoclonal antibodies are beginning to displace their antiquated progenitors, polyclonal antisera, in many facets of immunology. Their homogeneity, specificity, and availability make hybridoma-derived antibodies the immunological reagents of the future in immunoassays, immuno-affinity chromatography, immunotherapy, and areas yet to be defined.
Lactate dehydrogenase isoenzyme-1: changes during the first day after acute myocardial infarction.
Authors: Bruns D E , Emerson J C , Intemann S , Bertholf R , Hill K E , Savory J 
Published: January 2020

Abstract
We studied the time course of change of lactate dehydrogenase isoenzyme-1 (LD-1) in serum of patients suspected of having had an acute myocardial infarction. LD-1 was measured at intervals of 4-8 h during the first and second hospital days, by an immunochemical method. Of the 65 patients in this study, 26 had acute myocardial infarctions by traditional criteria. The ratio of LD-1 to total LD had greater diagnostic value than did LD-1 alone. In 90% of patients with myocardial infarction this ratio was increased within 12 h of admission, and all had increased ratios within 24 h. The false-positive rate was less than 1%, and an increased LD-1/total LD ratio had a predictive value of 96% for myocardial infarction. These results suggest that LD-1 is useful in the diagnosis of myocardial infarction on the first day of hospitalization.
Low-density-lipoprotein apoprotein B in plasma as measured by radial immunodiffusion and rocket immunoelectrophoresis.
Authors: Havekes L , Hemmink J , de Wit E 
Published: January 2020

Abstract
Radial immunodiffusion (RID) and rocket immunoelectrophoresis (RIE) are compared with respect to determination of LDL-bound apo B in plasma. Isolated VLDL could not enter a 15 g/L agarose gel when either technique was used. However, in the presence of plasma proteins, migration of VLDL into agarose was enhanced. Only when plasma samples were kept frozen before the assay was plasma VLDL unable to enter the agarose gel when RID was used. With RIE the contribution of plasma VLDL to the apo B determination under these conditions was not always negligible. Besides enhancing the entry of VLDL into the agarose, the presence of proteins also influences apo B immunoreactivity of LDL and VLDL. For measuring LDL-bound apo B directly in unfractionated plasma we recommend: (a) RID in 15 g/L agarose gel; (b) freezing the plasma samples before assay; (c) diluting the plasma samples in saline supplemented with protein in the same concentration as is present in plasma (70 g/L); and (d) using plasma as the assay standard.
A direct radioimmunoassay for aldosterone in unextracted serum and plasma.
Authors: Lee T P , Tan C H 
Published: January 2020

Abstract
We describe a novel radioimmunoassay procedure for the direct estimation of aldosterone in unextracted plasma and serum samples, in which interfering binding proteins are digested by Proteinase K (Tritirachium alkaline proteinase, EC 3.4.21.14), a powerful proteolytic enzyme. Heating at 75 degrees C for 15 min inactivates the enzyme before radioimmunoassay. Alternatively, EDTA may be used to inactivate the enzyme. The antibody-bound fraction is then precipitated with polyethylene glycol and isolated by centrifugation. This easy method eliminates extraction and purification and gives accurate and reliable results. The total time required for 100 estimations, including counting time, is about 6 h.
Simultaneous quantitation of zinc protoporphyrin and free protoporphyrin in erythrocytes by acetone extraction.
Authors: Hart D , Piomelli S 
Published: January 2020

Abstract
Erythrocyte protoporphyrin content is increased in several human and veterinary disorders in which heme synthesis is disrupted. The nature of the defect determines whether zinc protoporphyrin, unchelated (free) protoporphyrin, or both are present in the erythrocytes. Extraction of the protoporphyrin into acetone/water (80/20 by vol) is a simple, rapid technique by which each protoporphyrin species is delivered into solution without removing zinc from zinc protoporphyrin. The ratio of zinc protoporphyrin to total protoporphyrin concentration correlated significantly with the ratio of fluorescence emission intensities at the zinc protoporphyrin peak and at an isosbestic point. This concentration ratio may be used with a quantitative measure of total erythrocyte protoporphyrin to define the absolute zinc protoporphyrin and free protoporphyrin content of erythrocytes.
Serum iron and total iron-binding capacity compared with serum ferritin in assessment of iron deficiency.
Authors: Peter F , Wang S 
Published: January 2020

Abstract
Ferritin values for 250 selected sera were compared with values for iron, total iron-binding capacity (TIBC), and transferrin saturation, to assess the potential of the ferritin assay for the detection of latent iron deficiency. The specimens were grouped (50 in each group) according to their values for iron and TIBC. In Group 1 (low iron, high TIBC) the saturation and ferritin values both indicated iron deficiency in all but one. In the 100 specimens of Groups 2 (normal iron, high TIBC) and 4 (normal iron, high normal TIBC), the saturation values revealed 16 iron-deficient cases, the ferritin test 55. For Groups 3 (low iron, normal TIBC) and 5 (low iron, low TIBC), the ferritin test revealed fewer cases of iron deficiency than did the saturation values (37 cases vs 51 cases, in the 100 specimens). Evidently the ferritin test detects iron deficiency in many cases for whom the serum iron and TIBC tests are not positively indicative. The correlation of serum ferritin with iron, TIBC, and transferrin saturation in the five groups was good only in the case of specimens for which the TIBC was normal; if it was abnormal the correlation was very poor.
Sickle cell crisis as evaluated from measurements of hydroxybutyrate dehydrogenase and myoglobin in plasma.
Authors: Roth E F , Bardfeld P A , Goldsmith S J , Radel E , Williams J C 
Published: January 2020

Abstract
Data on plasma hydroxybutyrate dehydrogenase activity (I) and myoglobin concentration were used to evaluate painful sickle cell crises. I was increased during non-crisis steady state in patients with sickle cell disease as compared to normal values (232, SD 79.7 vs 85, SD 33 Sigma units/mL). During crisis, the mean value for I increased further to 379 (SD 139) Sigma units/mL. For 12 patients evaluated both during steady state and crisis, there was a mean increase in plasma I of 131% (SD 76%). Repeated determinations of I in sickle cell disease patients during several months while they were in steady state showed that baseline I varied by no more than 20% from the mean. Plasma myoglobin in patients with sickle cell disease was not above normal, but during crisis 21 of 39 patients tested had increased plasma myoglobin concentrations. Our data suggest that I may be a useful indicator of sickle cell crisis when the patient's own baseline value is available for comparison. Plasma myoglobin measurements give evidence of muscle damage during crisis with high specificity but low sensitivity.
Evaluation of the operating characteristics of a bichromatic analyzer, the ABA-200.
Authors: Elser R C , Garver C G 
Published: January 2020

Abstract
We investigated certain operating characteristics of a new bichromatic analyzer, the ABA-200. The reliability of filter factor assignments was found to be within 3% for NADH and p-nitroaniline, 6% for p-nitrophenol. The accuracy and precision of the dilutor is a function of dilution ratio and sample size. Accuracy of dilution ratio was within 3% at all ratios tested except 1:201 at a sample volume of 1.25 microL. Coefficients of variation were less than 1.3% at all ratios. Photometric linearity was observed to 3.2 Ad for all filter sets. Photometric precision measurements showed a CV of 0.27% at an absorbance difference of 1.0.
Improved method for determination of high-density-lipoprotein cholesterol I. Isolation of high-density lipoproteins by use of polyethylene glycol 6000.
Authors: Izzo C , Grillo F , Murador E 
Published: January 2020

Abstract
We describe a modified method of precipitating low- and very-low-density lipoproteins with polyethylene glycol, for quantitation of high-density lipoprotein cholesterol. A 100 g/L concentration of polyethylene glycol 6000 in a buffered (pH 10) solution is used. Under these conditions precipitation of beta-lipoproteins is complete. Values for HDL cholesterol as measured with this method fully correspond to those obtained on separating the lipoproteins by ultracentrifugation or with heparin-Mn2+, 46 mmol/L; are slightly higher than those obtained with heparin-Mn2+, 92 mmol/L; and are significantly higher than those determined after precipitation with polyethylene glycol, 100 g/L at pH 8.0. Comparison with results by the ultracentrifugation method showed excellent correlation (r = 0.957) with a good correspondence of results (slope 1.065 and y-intercept -22.231); comparison with the heparin-Mn2+, 46 mmol/L, method gave r = 0.998 with slope of 0.985 and y-intercept 2.963. The method is unaffected by precipitation and centrifugation time and temperature (up to 24 h with 4-22 degrees C temperature for precipitation and between 10 and 30 min with 4-22 degrees C temperature for centrifugation). This extremely simple method is particularly suitable for routine analyses of many samples, even in small laboratories.
Fluorescent spot test for detecting carbohydrate-splitting enzymes in meconium.
Authors: Hsieh M C 
Published: January 2020

Abstract
I describe a fluorescent spot test for detecting the acidic glycosidases in meconium. Meconium is mixed with various 4-methylumbelliferylglycosides at the appropriate pH. In the presence of carbohydrate-splitting enzymes, 4-methylumbelliferone, a strongly fluorescent compound, is released. The reaction mixture, when spotted on chromatography paper and viewed under ultraviolet light, exhibits a bright fluorescence for specimens containing acidic glycosidases. The technique is applicable to any test that involves production of fluorescent products from non-fluorescent reactants. The procedure was applied to meconium specimens selected because of increased albumin content known to be associated with cystic fibrosis in newborns. The presence of beta-D-fucosidase in meconium was correlated to increased albumin content. Detection of beta-D-fucosidase by the present procedure may be useful as a screening test for cystic fibrosis.
New method for determining lecithin and sphingomyelin in amniotic fluid.
Authors: McDonald L J , Robin N I , Siegel L 
Published: January 2020

Abstract
We describe a new method of complete analysis for lecithin, lysolecithin, and sphingomyelin in amniotic fluid. The analysis is based on alkaline hydrolysis of the lecithins and the enzymic hydrolysis of sphingomyelin. The choline formed in each instance is enzymically phosphorylated with [gamma-32P]ATP to yield [gamma-32P]phosphorylcholine, which is isolated by anion-exchange chromatography and shown to be stoichiometrically related to lecithin, lysolecithin, and sphingomyelin. Other phospholipids do not interfere. Using this methodology, we developed three potential approaches to the assessment of fetal lung maturity: the ratio of lecithin plus lysolecithin (total lecithin) to sphingomyelin, the total lecithin concentration, and total lecithin as a percentage of total amniotic fluid phospholipids. All three indices were compared with the lecithin/sphingomyelin ratio obtained by a chromatographic procedure. Our data suggest that measuring the percentage of total lecithin may provide the best means of evaluating fetal lung maturity, but a final judgment must await clinical investigation.
Gas-chromatographic assay of free phenytoin in ultrafiltrates of plasma: test of a new filtration apparatus and specimen stability.
Authors: Joern W A 
Published: January 2020

Abstract
I describe a gas-chromatographic procedure involving a nitrogen detector for "free" (or "unbound") phenytoin in the concentration range 0.2-4.0 mg/L in ultrafiltrates of plasma. The CV (n = 10) for the assay was 2.9% for a 0.49 mg/L concentration, 1.5% for 2.02 mg/L. The sensitivity was 0.05 mg/L. The ultrafiltration process ("Ultra-Free" filters) used to separate the free phenytoin fraction from the bound fraction was tested. The mean of and CV for free phenytoin concentrations measured in eight replicate serum filtrates were 0.68 mg/L and 15%; for eight replicate plasma filtrates the values were 0.42 mg/L and 2.9%. Thus serum is not suitable for this procedure. Storage of plasma before filtration under a wide variety of times and temperatures has an insignificant effect upon the filtration process. Some evidence was found of occasional protein "leakage" through the filters.
Evaluation of a routine method for determination of calcium oxalate crystal growth inhibition in diluted urine samples.
Authors: Tiselius H G , Fornander A M 
Published: January 2020

Abstract
We have evaluated a routine method for determination of the inhibition of calcium oxalate crystal growth in diluted urine samples. A crystallization inhibition index is calculated from the decrease in [14C]oxalate concentration in a metastable solution of calcium chloride and sodium oxalate after addition of seed crystals of calcium oxalate. The coefficient of variation between different determinations on the same sample is less than 1.5%, and there is good correspondence between indices obtained by this method and by a more laborious older method. We also studied the influence of different urinary constituents on the crystal growth rate in the system; whereas there was significant inhibition with citrate, chondritin sulfate, and pyrophosphate, no effects were observed with ordinary urinary concentrations of calcium, magnesium, and oxalate. The mean inhibition index was lower in a group of male patients with calcium oxalate stone disease than in a control group of normal men.