bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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

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

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

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

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.
Short- and long-term biological variation in analytes in urine of apparently healthy individuals.
Authors: Shephard M D , Penberthy L A , Fraser C G
Published: January 2020

Intra-individual, interindividual, and analytical components of variation for each of 10 urine analytes were estimated from results obtained on analysis of urine specimens from 10 apparently healthy young men. In spot urines, urea and osmolality showed strong individuality, but intra-individual variances were larger than interindividual variances for sodium, urate, phosphate, and glucose. Urea and osmolality displayed strong individuality in daily urines, whereas sodium (when results were expressed in output terms), urate, potassium, and total protein (when results were expressed in concentration units) had intra-individual variances larger than interindividual variances. In monthly urines, calcium and glucose, in concentration terms, and phosphate, in output terms, exhibited strongest individuality. Analytical variance was a significant percentage of the total variance for total protein and glucose; the analytical methods we used for these analytes were probably unsatisfactory. A series of analytical goals for imprecision, based on biological variation, were derived. Although these goals may not be applicable in all clinical situations, they represent the beginning of a data base in the literature.
Centrifugal analysis for plasma kallikrein activity, with use of the chromogenic substrate S-2302.
Authors: Ito R , Statland B E
Published: January 2020

The amidolytic activity of activated kallikrein in plasma can be measured by use of the chromogenic substrate, S-2302 (H-D-Pro-Phe-Arg-pNA). Plasma prekallikrein was activated to kallikrein by exposure to 50 mg/L dextran sulfate in acetone/water (35/65 by vol) at 0 degrees C for 15 min. The acetone slows anti-kallikrein activity and increases the kallikrein activity by 30%. The 37 degrees C reaction mixture contained 0.54 mmol of S-2302 substrate per liter of Tris buffer (pH 7.5 at 37 degrees C). We monitored the change in absorbance at 405 nm for 60 s. The specificity of the substrate for kallikrein was demonstrated by using plasma deficient in prekallikrein (Fletcher trait) diluted with pooled normal human plasma. We recommend collecting blood specimens with sodium citrate as the anticoagulant and with use of a double-syringe technique and all-plastic containers. Plasma kallikrein activity with Chromozym-PK (Bz-Pro-Phe-Arg-pNA) as substrate (y-axis) compared with S-2302 as substrate (x-axis) gave the relation: y = 0.28x + 0.82 (r = 0.94). Day-to-day analytical variation was 2.4% for a pooled plasma with a mean value of 85.9 mukat/L. The mean (and 2 SD) for 50 healthy adults was 86.4 (32.4) mukat/L.
Test of radioimmunoassay validity in the presence of an isotope effect.
Authors: Xing S , Zheng S , Cekan S Z
Published: January 2020

An isotope effect, manifested as delayed elution of the labeled moiety, was detected in CO-chromatography of testosterone with [1,2,6,7-3H]testosterone on Celite. The isotope effect was smaller for [1,2-3H]testosterone and even smaller, but still significant, for [7-3H]testosterone. Because of the isotope effect, the test of validity of a testosterone radioimmunoassay had to be modified. Instead of testing the constancy of values for specific activity in individual chromatographic fractions, the slopes of specific activities exhibited by mixtures of plasma testosterone (pooled specimens of plasma from men and from women) with [1,2-3H]testosterone were compared with that yielded by authentic testosterone mixed with the same tracer. Because the slopes were statistically indistinguishable, the assay of testosterone in these materials appears to be valid. We suggest that comparison of the slopes of specific activities be used as the basis of validity tests whenever such an isotope effect is present.
Positive interference by danazol in a testosterone radioimmunoassay kit procedure.
Authors: Sharp A M , Fraser I S , Robertson S , Turtle J R
Published: January 2020

We describe a problem in measuring serum testosterone concentrations in the serum of women who are taking danazol. The Diagnostic Products Corporation testosterone radioimmunoassay gives very high apparent testosterone concentrations in these women and the value obtained depends on the volume of serum extracted per assay tube. Chromatography of the serum extracts on Sephadex LH-20, but not on Celite, before radioimmunoassay reduced these high apparent testosterone concentrations to less than that found in normal women.
Prostatic acid phosphatase as measured with two radioimmunoassay kits in the detection of prostatic adenocarcinoma.
Authors: Brody J P , Savory J , Sturgill B C , Lehman M R , Wills M R
Published: January 2020

Serum prostatic acid phosphatase concentration was measured with two commercially available radioimmunoassay kits. Results were compared with histological evidence of prostatic adenocarcinoma obtained at autopsy in 33 patients. The serum assay did not differentiate significantly (p greater than 0.1) between patients with adenocarcinoma and those without. We conclude that the test, at least as performed by use of these kits, is of little value in the detection of occult disease.
Preparation of whole blood for liquid scintillation counting.
Authors: Moore P A
Published: January 2020

Liquid scintillation counting of 3H-labeled whole-blood samples is severely impaired owing to quenching by blood pigments. In this study, dry oxidation and chemical solubilization followed by decolorization were the two general methods used to eliminate color quenching. Three blood volumes were examined: 0.25, 0.50, and 1.0 mL. Dry oxidation yielded complete recoveries of 3H label with counting efficiencies greater than 30% for up to 1.0 mL of blood. Although blood volumes larger than 0.25 mL can be used with chemical solubilization and decolorization, treatment of 0.25 mL of blood gave the highest counting efficiencies, with count rates comparable to those for 1.0-mL samples.
Radioenzymic measurement of norepinephrine, epinephrine, and dopamine: stability, enzymic activity, and sensitivity.
Authors: Saar N , Bachmann A W , Gordon R D
Published: January 2020

We investigated factors affecting sensitivity and reproducibility of radioenzymic (catechol-O-methyltransferase) measurement of plasma catecholamines. There was no apparent deterioration of catecholamine during storage at -20 degrees C for 240 days. Accuracy and sensitivity of the assay depended mostly on the method of transferase preparation; its preparation by adjusting the pH to 6.8 before fractionation with ammonium sulfate resulted in an unsuitable enzyme with a relatively high background-radioactivity count, particularly for neorepinephrine and dopamine.
Effect of serum dilution on apparent unbound bilirubin concentration as measured by the peroxidase method.
Authors: Ahlfors C E
Published: January 2020

I studied the effects of serum dilution and oxidation of albumin-bound bilirubin on the accuracy of results by the peroxidase method for assessing bilirubin-albumin binding. The apparent concentration of unbound bilirubin decreases with dilution of bilirubin-enriched serum or defatted-albumin solutions, the effect being more marked with serum. The decrease in apparent unbound bilirubin does not appear to be due to slow oxidation of albumin-bound bilirubin. Instead, the bilirubin-albumin complex has a much lower apparent dissociation rate constant (K-1) in serum (0.0033 [SD 0.0002] s-1) than in solutions of defatted-albumin (0.017 [SD 0.006] s-1), causing the dissociation of the complex to be rate-limiting when serum is analyzed at the currently recommended 40-fold dilution and peroxidase concentration (0.11 mu mol/L). In addition, dilution appears to enhance bilirubin binding by serum but not by defatted-albumin solutions. Decreasing the serum dilution and peroxidase concentration may significantly improve the accuracy of the peroxidase test. The actual correlation between clinical bilirubin toxicity and specific unbound bilirubin concentrations, however, remains to be determined.
Standardization of immunochemical determinations of serum albumin.
Authors: Keyser J W , Fifield R , Watkins G L
Published: January 2020

When we compared four commercially available preparations of human serum albumin with the human serum standard IFCC 74/1 by radial immunodiffusion, by immunoprecipitation turbidimetry, by laser nephelometry, and by "rocket" immunoelectrophoresis, three of the preparations gave almost "theoretical" results with the immunoprecipitation turbidimetric method. Results by the other three methods tended inconsistently to be low. Four pools of normal human serum were also analyzed for albumin by these four immunochemical methods, again with IFCC 74/1 as the reference standard. The results were virtually identical with those obtained by fractionation with 1.8 mol/L sodium sulfate and determination of protein nitrogen in the filtrate. We suggest that a combination of (a) fractionation of a pool of normal human serum in this way and (b) critical comparison with selected commercial preparations of human serum albumin will permit standardization of the serum albumin determination.
Volume of blood removed for analytical purposes during hospitalization of low-birthweight infants.
Authors: Nexø E , Christensen N C , Olesen H
Published: January 2020

Iatrogenic hazards may be induced by blood sampling in very-low-birthweight neonates. We report the number and types of analyses performed on 20 neonates with a birthweight below 1500 g during their first four weeks of hospitalization. Blood was sampled one to 13 times per infant per day on 382 of the 435 total days of hospitalization. The average blood loss was 7 to 51 mL per kilogram of body weight per four weeks--that is, from 5 to 45% of the calculated total blood volume. Of the blood removed, about 25% was in excess of the need for analytical procedures. Of the analyses, 40% were for acid-base, sodium, and potassium analyses--analyses for which transcutaneous methodology has been or is being developed. We conclude that because of the risks for low-birthweight neonates, procedures for blood sampling and analysis should periodically be reviewed, so as to minimize the number of samplings and the amount of blood removed.
A bioluminescence micromethod for measuring chloramphenicol in serum.
Authors: Boeckx R L , Brett E M
Published: January 2020

Bioluminescence provides a sensitive analytical approach for the measurement of low concentrations of ATP and can be used to monitor any reaction in which ATP is consumed or synthesized. We describe a quick, sensitive method involving bioluminescence for the quantitation of chloramphenicol in serum. Chloramphenicol acetyl transferase catalyzes the acetylation of chloramphenicol in the presence of acetyl coenzyme A. ATP is consumed when the acetylation reaction is coupled to the acetyl coenzyme A synthetase reaction. Residual ATP is then assayed with the firefly luciferin-luciferase reaction. The procedure can be completed in less than 1 h and requires as little as 20 microliter of serum. The response of the assay is linear with concentration through a range of 2 to 20 mg/L and shows good correlation with a gas-chromatographic method (r = 0.978) and a radioenzymic method (r = 0.985). No significant interference was found from five other antibiotics tested. The small sample requirement makes the assay especially applicable to infant and pediatric monitoring, where the effects of toxicity are greatest.
Improved method for quantitation of B apoprotein in plasma lipoproteins by electroimmunoassay.
Authors: Reardon M F , Poapst M E , Uffelman K D , Steiner G
Published: January 2020

The B apoprotein occurs in a wide range of plasma lipoproteins, which are heterogenous both with respect to size and to composition. Immunochemical recognition of the apoprotein is influenced by the nature of the particle in which the apoprotein is found, presumably due to the masking of the antigenic sites by lipoprotein lipid. Consequently, it is difficult to provide suitable standards for use in routine electroimmunoassay procedures of the B apoprotein, particularly for triacylglycerol-rich lipoproteins. We have devised a procedure whereby lipoprotein samples, independent of their initial size and composition, are reduced, by use of a bacterial lipase, to a common size and composition, which is almost identical to that of the standard. This permits an assay that may be easily used routinely. It provides a far more reliable estimate of the absolute B apoprotein mass in plasma lipoproteins of the very-low- and low-density lipoprotein spectrum than has been previously available.
Colorimetric method for free fatty acids in serum validated by comparison with gas chromatography.
Authors: Brunk S D , Swanson J R
Published: January 2020

We compared results by a simplified colorimetric copper-soap method for serum free fatty acids (Clin, Chem. 19: 419, 1973, modified) with those by a gas--liquid chromatographic method. The modified method requires only 100 microliters of sample, its standard curve is linear from 0.1 to 4.0 mmol/L (reference interval for adults: 0.2 to 0.8 mmol/L), and it is suitable for use with newborns. Comparison with the gas--liquid chromatographic method (n = 51) over a wide concentration range gave a correlation coefficient of 0.989. Between-run CVs varied from 4 to 10%, analytical recoveries from 97 to 104%. Triglycerides, salicylates, hemoglobin, and anticoagulants (except citrate) do not interfere, but bilirubin and phospholipids give small positive interferences. The colorimetric assay is used, along with other routine tests, to assess lipid status and estimate kernicterus risk in neonatal intensive-care patients receiving lipid nutrition parenterally.
Automated discrete kinetic method for erythrocyte acetylcholinesterase and plasma cholinesterase.
Authors: Lewis P J , Lowing R K , Gompertz D
Published: January 2020

We describe an automated kinetic method for erythrocyte acetylcholinesterase (EC 3.1.1.7) and plasma cholinesterase (EC 3.1.1.8) based on Ellman's colorimetric method. Quinidine sulfate is used as an inhibitor of plasma cholinesterase during the measurement of erythrocyte acetylcholinesterase activity, obviating the need for washing the erythrocytes before lysis. Results by this method are compared with those obtained by the electrometric delta pH method of Michel. To emphasize the need for measuring both erythrocyte acetylcholinesterase and plasma cholinesterase activity in workers exposed to organophosphate pesticides, we present a study of serial activities of both enzymes in a person accidentally exposed to demeton-S-methyl.
Aluminum concentrations in serum of hemodialysis patients.
Authors: Gorsky J E , Dietz A A
Published: January 2020

Aluminum has been implicated in the etiology of the progressive dialytic encephalopathy. Data are presented on samples taken from patients on maintenance hemodialysis, during treatment. Aluminum was determined by electrothermal atomic absorption spectroscopy. Hemodialysis had no significant effect on serum aluminum concentrations, which ranged from 27 to 254 micrograms of Al per liter (1.00 to 9.42 mumol/L). Isolated ultrafiltration removed part of the serum aluminum, but most remained bound to a nonfiltrable component. These results are evaluated in the light of present knowledge concerning dialysis dementia.
Determination of testosterone in plasma from men by gas chromatography/mass spectrometry, with high-resolution selected-ion monitoring and metastable peak monitoring.
Authors: Finlay E M , Gaskell S J
Published: January 2020

Highly specific methods are described for determining testosterone in plasma or serum from men. Extract fractions obtained by selective isolation procedures are converted to tert-butyldimethylsilyl (TBDMS) oximes/TBDMS ethers or methyl oximes/TBDMS ethers and analyzed by gas chromatography/mass spectrometry in the high-resolution selected-ion monitoring or metastable peak-monitoring modes. [2H3]Testosterone and unlabeled 17-epitestosterone are used as the respective internal standards. When we applied the two procedures to analysis of samples of pooled plasma and serum used for external quality assessment of routine assays, the results agreed well. Interlaboratory values for mean concentrations obtained by routine immunoassays (y) consistently exceeded values obtained by our technique (x), although the values closely correlated (r = 0.997; y = 1.008x + 0.564 nmol/L).
Fluorescence polarization immunoassay. II. Analyzer for rapid, precise measurement of fluorescence polarization with use of disposable cuvettes.
Authors: Popelka S R , Miller D M , Holen J T , Kelso D M
Published: January 2020

This instrument, developed for quantitating fluorescence polarization immunoassays, automatically measures both polarization components and computes a polarization value corrected for background and optical bias. An electronically switched liquid crystal provides a nonmechanical means of rotating the plane of polarization in the excitation optics. The electronic design features digital integration and microprocessor controlled functions. Readings are made in disposable 12 X 75 mm round culture tubes. in less than 10 s. Results are precise to 0.001 polarization unit, linear from 10(-7) to 10(-10) mol of fluorescein per liter, and correlate well with those obtained with other "high-performance" instrumentation.
Evaluation of a method for enzymic radiochemical assay of tobramycin and amikacin in serum.
Authors: McKnight R P , Willis J E
Published: January 2020

This enzymic radiochemical procedure for measuring tobramycin and amikacin in serum is based on the transfer of the 14C-acetyl group from [14C]acetyl-coenzyme A to the 6' nitrogen atom of the drug by the enzyme kanamycin 6'-acetyltransferase (EC 2.3.1.55). The transfer, stoichiometric and quantitative, is complete after 10-min incubation at 37 degrees C. The labeled acetylaminoglycoside is adsorbed onto phosphocellulose paper discs, which are washed to removed any unreacted [14C]acetyl-coenzyme A. The radioactivity is then eluted into liquid scintillation counting vials and counted for 1 min each. The assay detects as little as 2 ng of either drug and the standard curve is linear into the toxic range of concentrations. Most of the commonly administered aminoglycosides act as substrates in the assay, except for the C1 component of gentamicin C complex. Neither hemolysis, lipemia, nor icterus interfere with the assay. Results compare favorably with those determined by radioimmunoassay and a microbiological method.
Direct spectrophotometry of total bile acids in serum.
Authors: Mashige F , Tanaka N , Maki A , Kamei S , Yamanaka M
Published: January 2020

In this simple and direct method for determining total bile acids in serum, the serum was mixed with sodium pyruvate, a lactate dehydrogenase blocker, and bile acids were then measured spectrophotometrically after the following enzyme reaction. Bile acids are converted to 3-oxo bile acids with 3 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.50) with concomitant reduction of NAD+ to NADH. The hydrogen in the NADH generated is transferred by diaphorase (EC 1.6.4.3) to nitrotetrazolium blue to yield diformazan 540 nm). Analytical recovery of the various bile acids in serum averaged 96.2%. The CV for the day-to-day variation was 4.3%. Normal values are less than 7 mumol/L. Total serum bile acids were estimated by this method in 118 fasting patients with various liver diseases. This determination is clearly shown to be useful as a liver-function test.
Usefulness of serum nucleotide pyrophosphatase and phosphodiesterase I activities in classifying liver disease.
Authors: Haugen H F , Ritland S , Blomhoff J P , Solberg H E , Skrede S
Published: January 2020

Nucleotide pyrophosphatase and phosphodiesterase I activities were determined in sera from 126 patients with different types of liver disease and in two additional groups of patients with intra- and extrahepatic cholestasis, respectively. Both activities probably represent the same enzyme, and were positively correlated with alkaline phosphatase, lipoprotein X, and several other tests reflecting cholestasis. Also, we found by discriminant analysis that tests for cholestasis frequently replaced the results of both enzymes. In some groups of liver disease, nucleotide pyrophosphatase and phosphodiesterase I were correlated with the concentrations of prealbumin and albumin. The sensitivity of phosphodiesterase I (and nucleotide phosphatase) is rather low when compared with alkaline phosphatase, and we do not recommend it for use in the clinical routine. Nevertheless, it appears to be of potential value for studies on classification of liver diseases, adding information to a panel of 20 commonly used "liver tests" by appearing in some of the best four test-sets for distinguishing between groups of liver disease by discriminant analysis.
Spectrophotometry of tissue thromboplastin in cerebrospinal fluid.
Authors: Hische E A , Tutuarima J A , van der Helm H J
Published: January 2020

We describe a two-stage method for measuring thromboplastin in cerebrospinal fluid, based on the amidolytic determination of the generation rate of Factor Xa. We investigated the effect of variations in the duration of incubation, and in pH, temperature, and concentrations of calcium, buffer, and prothrombin complex (source of Factors VII and X). Optimal assay conditions are specified. The detection limit is 6 units/L and the results indicate an upper limit of normal of 14 units/L. The coefficients of variation were 7.7% within-day and 9.2--16.0% day-to-day, depending on the concentration.
Use of receiver operating characteristic curves to evaluate the clinical performance of analytical systems.
Authors: Robertson E A , Zweig M H
Published: January 2020

The usefulness of an analytical system in patient care is ultimately judged not by its analytical performance but by its clinical performance, i.e., its ability to separate apparently similar patients into two subgroups, one of which has a particular clinically important condition and another subgroup which does not. This clinical performance can be studied with the tools of signal detectability theory, originally developed to analyze the performance of radar and data-transmission systems. Each classification made by an analytical system may be categorized as a true-positive, true-negative, false-positive, or false-negative decision. For laboratory tests the proportion of decisions in each category depends on the biological overlap between the two subgroups, the analytical performance of the system, and the decision level chosen. The clinical performance of the analytical system for all possible decision levels is represented by the receiver operating characteristic curve, which plots the true-positive rate against the false-positive rate. The use of these curves permits comparison of alternative analytical techniques at equal true-positive rates and at all possible decision levels. These comparisons show the effect of analytical improvements on clinical performance.
Potentiometric analysis for sodium and potassium in biological fluids.
Authors: Langhoff E , Steiness I
Published: January 2020

Results obtained with a potentiometric analyzer, NOVA 1, specific for sodium and potassium, were compared with those by flame photometry. Both instruments showed linearity within a physiological range of sodium and potassium concentrations and had similar precisions. Volume displacements from addition of albumin or Intralipid to aqueous samples yielded the predicted lower flame-photometric results because of the relative decrease in sample water. There may be a small interaction between sodium and albumin. Physiological measurements on plasma from uremic patients showed no change after dialysis that could be ascribed to a decrease in interaction of these ions with creatinine and urea. Potentiometric values for sodium and potassium did not differ significantly, whether measured in cerebrospinal fluid or in the corresponding plasma. Results for urine were the same potentiometrically and by flame photometry.
Comparison of enzyme-linked immunosorbent assay and radioimmunoassay for prostate-specific acid phosphatase in prostatic disease.
Authors: Griffiths J , Rippe D F , Panfili P R
Published: January 2020

We compared results by an enzyme-linked immunosorbent assay (ELISA) with those by a standard radioimmunoassay (RIA) for detection and quantitation of prostate-specific acid phosphatase (EC 3.1.3.2) in serum. Control subjects, patients with benign prostatic hyperplasia, and patients in all four clinical stages of prostatic adenocarcinoma were tested. The upper limit of normal (95% of the population) by the ELISA was 2.0 micrograms/L, and by the RIA was 2.2 micrograms/L. In prostatic adenocarcinoma stage I (not detectable by digital rectal examination), ELISA was slightly more sensitive than RIA, but sensitivity was still relatively low (20%). As tumor mass increased (stages II through IV), the frequency of increased concentrations of prostatic acid phosphatase in serum also increased. We confirmed this increase in circulating enzyme in some cases of benign prostatic hyperplasia and suggest that this finding is related to either acinar cytolysis or an increase in acini size and number. Although prostate-specific acid phosphatase is not a cancer-specific enzyme, we conclude that its measurement may be of considerable value in monitoring prostatic disease.
Radioimmunoassay of apolipoprotein A-i. application of a non-ionic detergent (Tween-20) and solid-phase staphylococcus.
Authors: Maciejko J J , Mao S J
Published: January 2020

We describe two techniques for radioimmunoassay of apolipoprotein A-I (apoA-I) in human plasma, each involving use of a non-ionic detergent, Tween-20, to expose antigenic sites, and one involving "IgG SORB" (a suspension of killed staphylococci) as a solid-phase separator. Tween-20 (3.75 g/L) decreased nonspecific binding and unmasked the antigenic sites on the apoA-I molecule in plasma to the same extent as did a tedious delipidation procedure, without altering the binding affinity between apoA-I and apoA-I antibodies as determined by Scatchard analysis (Ka congruent to 2.83 X 10(8) L/mol). The widely accepted double-antibody immunoprecipitation technique for separating bound and unbound 125I-labeled apoA-I is time-consuming, owing to extended periods of incubation and centrifugation IgG SORB effectively separates bound from unbound 125I-labeled apoA-I and the reaction is complete within 10 min. On comparing concentrations of apoA-I in human plasma by the conventional second-antibody (y) and solid-phase IgG SORB methods (x), we found results by the two techniques to be reasonably identical (r = 0.98, y = 1.2x -- 0.17). The mean concentrations of apoA-I in plasma from 65 normal and five hyperlipidemic patients were 1.33 (SD 0.32) and 0.78 (SD 0.35) g/L, respectively, and apoA-I and high-density lipoprotein cholesterol were significantly correlated (r = 0.72, p less than 0.001).
Differential pulse polarography of the catalytic waves in serum from patients with urological cancers.
Authors: Lyons H , Adams J R , Jordan W P
Published: January 2020

Catalytic waves obtained from the perchloric acid-soluble fraction of serum in the presence of hexaminecobalt trichloride appear to conform to a Langmuir adsorption isotherm. Wave heights for sera from patients with untreated urological cancers significantly exceed those from normal subjects. In general, treatment with diethylstilbestrol decreased the wave height. Effects of some other chemotherapeutic agents on wave heights are also noted.
A reagent strip for measuring the specific gravity of urine.
Authors: Burkhardt A E , Johnston K G , Waszak C E , Jackson C E , Shafer S R
Published: January 2020

A solid-phase reagent for determination of urinary specific gravity (relative density) is described. This reagent strip, similar to others in the "N-Multistix" series (Ames), contains a polyacid whose acidity is sensitive to the ionic concentration in the urine in which it is immersed. As the acidity of the polyacid changes, pH changes are detected by a pH indicator within the reagent strip. In comparison studies, 84.4% of relative densities as measured with these reagent strips were within 0.005 of the corresponding results with a total-solids meter, and 89.9% were within 0.005 of the corresponding urinometer results. Adding a correction of +0.005 to the reagent-strip results for urines with high pH increased the percentage of results within 0.005 of the comparison method to 90.7% (TS meter) and 92.9% (urinometer). Lot-to-lot variability and reader-to-reader variability were both low. Reagent strip results are not affected by glucose, may be increased by albumin, and correlate with urea concentrations.
Lipoprotein quantification: an electrophoretic method compared with the Lipid Research Clinics method.
Authors: Warnick G R , Nguyen T , Bergelin R O , Wahl P W , Albers J J
Published: January 2020

We compared a turbidimetric electrophoretic method (Lipidophor) for lipoprotein quantification with the standardized Lipid Research Clinics (LRC) method. In the Lipidophor procedure, major lipoproteins are separated by electrophoresis on agarose gels, precipitated on the gels with phosphotungstate-Mg2+ reagent, and the resulting turbidity is measured densitometrically. Measurements of relative turbidity were converted into lipoprotein cholesterol values by the use of numeric constants provided by the manufacturer. Among-day CVs (n = 46) for the Lipidophor method were 6.0%, 3.6%, and 9.9% for cholesterol in the alpha-, beta-, and pre-beta lipoproteins, respectively. The Lipidophor alpha-cholesterol was significantly lower (n = 171 specimens) than the LRC high-density lipoprotein (HDL) cholesterol (514 vs 586 mg/L), and beta-cholesterol was significantly higher than the corresponding LRC low-density lipoprotein (LDL) cholesterol values (1505 vs 1409 mg/L). The linear relation between the two methods for lipoprotein cholesterol quantification is as follows: Lipidophor alpha = 0.77 LRC HDL + 63 mg/L with correlation coefficient (r) of 0.87; Lipidophor beta = 0.95 LRC LDL + 166 mg/L (r = 0.96); Lipidophor pre-beta = 0.57 LRC very-low-density lipoprotein + 39 mg/L (r = 0.82). We derived a revised algorithm for estimating lipoprotein cholesterol from turbidity measurements. Lipoprotein cholesterol values by the Lipidophor method agree well with those obtained by the LRC method when these constants are used.
Radioimmunoassay of corticotropin from plasma.
Authors: Gutkowska J , Julesz J , St-Louis J , Genest J
Published: January 2020

We describe a specific and highly sensitive radioimmunoassay for corticotropin (ACTH) in human plasma. As little as 1.9 pg of circulating ACTH can be detected per milliliter (0.44 pmol/L). ACTH is first extracted from plasma samples by adsorption onto pretreated Vycor glass powder, eluted from the adsorbent by acetone, and then lyophilized. For purification of 125I-labeled ACTH, a small octadecasilyl silica column is used. The mean (and SD) concentration of ACTH in plasma from 18 ostensibly normal subjects was 10.3 (4.3) pmol/L. After overnight suppression with dexamethasone in seven of these normal subjects, their ACTH values fell to 2.62 (1.3) pmol/L (p less than 0.0005). This assay will permit clinical evaluation of ACTH plasma concentrations in clinical investigation and of the effects of drug administration on circulating ACTH.
Evaluation of five enzymic kits for determination of triglyceride concentrations in plasma.
Authors: Walker R E , Bachorik P S , Kwiterovich P O
Published: January 2020

We evaluated five commercial enzymic kit methods (methods A-E) for the determination of triglyceride concentrations in plasma, by comparing each with the automated fluorometric procedure of the Lipid Research Clinics Program. Aliquots of 91 to 97 samples were analyzed with each kit and with the comparison method. The results obtained with all five kits were highly correlated with those of the comparison method (r = 0.97-0.99). Group mean triglyceride concentrations as determined with kits A and D did not differ significantly from those assayed with the comparison method. The other three kits gave values 6.5-7.5% higher than those by the comparison method (p less than 0.001). The relative biases between the kit and reference methods did not vary with triglyceride concentration for kits B, D, and E; kits A and C had concentration-dependent biases. Kits D and E were the most nearly precise and had coefficients of variation (CVs) of 3.1% or less. Kit B had CVs of 3.8-4.4%; the remaining two kits had CVs of 5.4-6.7%. On the basis of these results, we judged kits B, D, and E to perform most satisfactorily, from the standpoint of their precision and their concentration-independent relationships to the comparison method.
Molecular heterogeneity and shedding of a high-molecular-mass melanoma-associated antigen identified with monoclonal antibodies.
Authors: Ng A K , Giacomini P , Kantor R , Ferrone S
Published: January 2020

This review briefly discusses some recent developments in the use of monoclonal antibodies to study antigens of high molecular mass associated with melanomas, including information on their molecular profile, their heterogeneity, and the effect of interferon on their shedding by melanoma cells.
Radioimmunoassay for salivary estriol, with use of an 125I radioligand and a solid-phase separation technique.
Authors: Truran P L , Read G F , Walker S
Published: January 2020

This simple, rapid radioimmunoassay for salivary unconjugated estriol in the third trimester of pregnancy is based on use of a Sepharose-coupled antiserum and a radioiodinated tracer, and requires only a 15-min incubation. Estriol conjugates are shown not to be present in saliva in significant concentrations; therefore a preliminary extraction is unnecessary. Determinations of unconjugated estriol in matched specimens of plasma and saliva correlate well (r = 0.95). A provisional normal range for 30 weeks to term agrees closely with those reported by others. This assay can give results quickly for the large numbers of specimens generated by weekly or daily sampling regimes.
Four methods for glucose assay compared for various glucose concentrations and under different clinical conditions.
Authors: Giampietro O , Pilo A , Buzzigoli G , Boni C , Navalesi R
Published: January 2020

Glucose was measured by the ferricyanide, the Beckman glucose oxidase, and the hexokinase procedures in 228 plasma samples taken during standard oral glucose-tolerance tests in 17 normal subjects and in 21 chemical diabetics. The neocuproine method was also used to measure glucose concentration in 156 samples (78 before and 78 after dialysis) collected from six diabetic and uremic patients who were on maintenance hemodialysis. Ferricyanide in all conditions and neocuproine in uremic patients overestimated glucose concentrations over the entire experimental range as compared with either enzymic method. This bias or systematic error of the reducing vs the enzymic procedures, due to nonglucose reducing substances ("saccharoids"), becomes considerably greater when their concentration is increased as in chronic uremia. Also, the inverse relation between glucose concentration and overestimation of glucose by the reducing methods has been detected. With respect to the hexokinase method, a mild but significant underestimate of glucose oxidase readings has been observed for higher glucose concentrations. We find neocuproine to be the most imprecise of these procedures.
Implications of using different tissue ferritins as antigens for ferritin in serum: four radioimmunoassay kits compared.
Authors: van Oost B A , Willekens F L , van Neerbos B R , van den Beld B
Published: January 2020

We compared three serum ferritin radioimmunoassay kits and one noncommercial RIA for ferritin quantitation, with regression analysis of results for sera from 35 ostensibly healthy subjects. There was a good correlation (p less than 0.001) between these various RIAs, but the slope of the regression line varied widely, most probably because of lack of standardization of the serum ferritin assay. Determination of the ferritin content of purified samples of tissue ferritin revealed that the kits differ in specificity, differences for purified human spleen ferritin and human liver ferritin being larger than those for normal sera. Removing the iron from purified liver ferritin increased antiserum binding in two of the kits by twofold, but had no effect in two other kits. We conclude that commercial RIA methods for serum ferritin differ in specificity, and that this difference is related to the source of ferritin used in the production of the antibodies.
The multivariate reference range: an alternative interpretation of multi-test profiles.
Authors: Boyd J C , Lacher D A
Published: January 2020

To test the utility of multivariate interpretation of laboratory data, we developed a multivariate reference range based of the Mahalonobis distance (D2) measure. Results for 20 commonly measured clinical chemistry analytes were collated for two sophomore medical-school classes (118 and 143 individuals in 1979 and 1980, respectively). The data for each test were examined for fit to a gaussian (normal) distribution by using a Kolmogorov--Smirnov test. Those results discovered to have a non-normal distribution were "normalized" by used the of a two-stage log-exponential transform. After this transformation, the D2 distance for each student group followed the expected chi-square distribution with 20 degrees of freedom. For each student's D2 distance an associated chi-square percentile was derived, and a cutoff percentile (95%) was selected to differentiate multivariately the "normal" from "abnormal" test results. Whereas more than two-thirds of the students had univariate test abnormalities, fewer than 7% had abnormal multivariate D2 scores. Analysis showed that the multivariate reference range could sensitively detect minor variations of multiple analytes but could also be quite insensitive to highly abnormal results for a single analtye. The multivariate approach has promise as a tool to avoid unnecessary followup of falsely abnormal test results, but further study and validation in a clinical setting are required.
A candidate reference method for uric acid in serum. I. Optimization and evaluation.
Authors: Duncan P H , Gochman N , Cooper T , Smith E , Bayse D
Published: January 2020

We describe our optimization and evaluation of a candidate Reference Method for uric acid in serum. Reaction parameters were optimized for a manual, enzymic method for uric acid in which highly purified microbial uricase is used to quantitate uric acid by a differential ultraviolet procedure. We evaluated the method in terms of freedom from interferences, analytical recovery, precision, and comparison with five other uric acid methods. We conclude that (a) the candidate uric acid Reference Method exhibits the least interference; (b) all six methods exhibit satisfactory analytical recoveries and precision; and (c) results by all six methods agree well. As a result of this evaluation study, the manual ultraviolet uricase method for uric acid, with Tris as buffer, was chosen as the candidate Reference Method for uric acid.