bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific Automated Method for Measurement of Urinary Hydroxyproline
Authors: Seymour G C , Jackson M J
Published: January 2020

An automated continuous-flow method is described for estimating total hydroxyproline in urine. The method utilizes column chromatography on sulfonated polystyrene resin, the eluate being reacted with chloramine-T and p-dimethylaminobenzaldehyde to produce a colored complex that is measured at 560 nm. The method is sensitive and specific, and requires 50 min per analysis.
Evaluation of the Adaptation of the Glucose Oxidase/Peroxidase-3-Methyl-2-benzothiazolinone hydrazone-N, N-Dimethylaniline Procedure to the Technicon "SMA 12/60," and Comparison with Other Automated Methods for Glucose
Authors: Carey R Neill , Feldbruegge Donald , Westgard James O
Published: January 2020

We have evaluated the Technicon SMA 12/60 modification of a glucose oxidase/peroxidase-3-methyl-2-benzothiazolinone hydrazone-N, N-dimethylaniline method, and find it acceptable. Added bilirubin, creatinine, dextrans, and uric acid did not interfere. We compared values for patients’ sera by this method to those by the glucose oxidase/peroxidase-2,2'-azinodiethylbenzothiazoline-6-sulfonic acid, neocuproine, o-toluidine, ferricyanide, and hexokinase methods. For comparisons to the hexokinase method (which we used as a reference method), n = 371, slope = 1.00, y-intercept = 1.57 mg/dl, and bias = 2.05 mg/dl. For the method being evaluated, the run-to-run average monthly standard deviation was 2.9 mg/dl for a control product for which the mean was 85 mg of glucose per deciliter, and 4.3 mg/dl for a product for which the mean was 240 mg/dl. All six methods were compared for effects of uremic sera, icteric sera, and sera from patients receiving ascorbic acid therapy or hypoglycemic drugs.
Enzymatic Blood Glucose Determination by Colorimetry of N,N-Diethylaniline-4-Aminoantipyrine
Authors: Kabasakalian Peter , Kalliney Sami , Westcott Anita
Published: January 2020

The hydrogen peroxide produced from glucose by glucose oxidase action at pH 7 is determined by the peroxidase oxidative coupling of N,N-diethylaniline with 4-amino-antipyrine. A 20-µl sample of plasma or serum is reacted at room temperature for 10 min. The sensitivity of the method is such that 60 µg of glucose (300 mg/dl) in a final volume of 5 ml gives an absorbance of 0.8 at 553 nm with a 1-cm cell. Absorbances are linearly related to glucose concentrations as high as 10.00 g/liter.
Design of a Portable Solid-State Hemoglobinometer
Authors: Rose Angela W , Steadman John W
Published: January 2020

The most widely used and accepted method for hemoglobin determination is the cyanmethemoglobin method. However, laboratory spectrophotometers used with this procedure are not amenable to field use. We describe the design of a portable hemoglobinometer for use with the cyanmethemoglobin method. Solid-state light sources and detectors are used, and a simple meter readout of hemoglobin is produced. Results obtained with the portable hemoglobinometer are presented and compared with assays of the same blood by the usual methods.
Improved Automated Method for Determining Serum Albumin with Bromcresol Green
Authors: Lolekha Porntip H , Charoenpol Wasana
Published: January 2020

An automated method for determining serum albumin with bromcresol green according to Doumas et al. [Clin. Chim. Acta 31, 87 (1971)] was simplified and improved for use in routine analysis. The manifold is simpler, there is better sample separation and less sample interaction, both within-run and day-to-day run precision are excellent, and results agree well with those obtained by electrophoresis on cellulose acetate.
Interlaboratory Evaluation of Proficiency Testing in Urinary δ-Aminolevulinic Acid Analyses
Authors: Berlin Alexander , del Castilho Pierre , Smeets Jan
Published: January 2020

Twenty-six European laboratories have participated in a study of various methods used for determination of δ-aminolevulinic acid in urine, to determine to what extent they give comparable results when performed by different laboratories. None of the methods as used in the program appeared to be precise and accurate enough to allow each of several laboratories to detect the small differences in urinary δ-aminolevulinic acid that would result from differences in exposure to environmental lead. Variation among results obtained by different laboratories using the same technique probably reflects differences in the practical experience each laboratory had with the various techniques, rather than intrinsic problems with the methods themselves.
New Assay for Tryptophan and Its 5-Hydroxyindole Metabolites in Blood
Authors: Guilbault George G , Froehlich Peter M
Published: January 2020

We describe a new cation-exchange fluorometry procedure for separation and measurement of three 5-hydroxyindole metabolites of tryptophan in blood. The metabolites are detected and measured via the fluorescence emitted in the visible region when the separated metabolite is added to a hydrochloric acid-ascorbic acid mixture. The assay requires only 30 min and is both selective and sensitive. The normal concentration of 5-hydroxytryptamine (serotonin) in serum is 98 µg/liter; 5-hydroxyindole acetic acid and 5-hydroxytryptophan are normally present in concentrations of less than 20 µg/liter.
A Centrifugal Analyzer with a New All-Digital Measurement System
Authors: Avery J , Gregory R P , Renoe B W , Woodruff T , Malmstadt H V
Published: January 2020

An accurate, all-digital measurement system has been developed for use in a centrifugal analyzer system. The output of the radiation detector is converted directly to a digital count by a new type of charge-to-count converter. The converter is characterized by exceptional linearity and stability, and has a wide dynamic range. A gating and counting unit integrates the output of the charge-to-count converter and simultaneously measures the period of integration. The integration effectively discriminates against noise and allows an optimum amount of information to be extracted from the signal during the measurement period. Measurement of the integration period reduces requirements for synchronization and control devices, thus simplifying overall analyzer design. Control and data manipulation functions are performed by a minicomputer. The programs were written in OS/8 FORTRAN. The basic measurement principles of the new system and test results are described.
High-Resolution Gas-Chromatographic Analysis of the Volatile Constituents of Body Fluids, with Use of Glass Capillary Columns
Authors: Novotny Milos , McConnell Michael L , Lee Milton L , Farlow Raleigh
Published: January 2020

Trace volatile constituents of human urine, serum, and cerebrospinal fluid were concentrated on a porous polymer precolumn, and resolved with high-efficiency glass capillary columns. Thin-film glass columns facilitate effective resolution of underivatized compounds within the volatility range up to docosane in relatively short analysis times. Glass capillary columns coated with stationary phases of different polarity were used. Recorded volatile metabolic profiles of human urine are altered after the sample is treated with β-glucuronidase and sulphatase.
Evaluation of a Solubility Test Kit and an Automated Machine for Detecting Hemoglobin S
Authors: Wilson Sylvia M , Schmidt Robert M
Published: January 2020

A solubility test kit (Sicklequik) and an instrument (SCAT Screener) designed to semiautomate the reading of the solubility test for the detection of hemoglobin S were evaluated for accuracy, precision, and specificity. Two hundred blood samples from persons with normal and variant hemoglobins were tested. Results were satisfactory for the test kit. However, the instrument gave incorrect results for 7% of the samples tested for hemoglobin S.
Evaluation of an Automated Selective-Ion Electrolyte Analyzer for Measuring Na+, K+, and Cl- in Serum
Authors: Lustgarten Jack A , Wenk Robert E , Byrd Charles , Hall Barbara
Published: January 2020

An automated analyzer, in which ion-selective electrodes are used to measure sodium, potassium, and chloride in serum, was assessed in a clinical setting. Day-to-day precision, evaluated by replicate analysis of serum pools, yielded the following coefficients of variation for sodium, potassium, and chloride, respectively: 0.99%, 1.39%, and 0.67%. Values for chloride in both commercial control sera and aqueous standards were linearly related to concentration over a range of at least 10-220 mmol/liter; however, results with the potassium and sodium electrodes showed slight curvilinearity over the range 0-24 and 10-220 mmol/liter, respectively. Mean recoveries for sodium, potassium, and chloride for concentrations covering the clinically important ranges were 98.3-102.3%, 95.9-100.0%, and 97.8-102.0%. The only important differences between experimental and comparison methods in sera were falsely high values obtained with the ion-selective electrode for K+ (caused by supranormal ammonia concentrations) and for Cl- (caused by administered bromide). Mean sodium and chloride values obtained with the electrode did not differ significantly from values obtained by flame-emission photometry or coulometry for duplicate patients’ specimens, but potassium values did differ slightly (P = .05).
Higher Copper Concentrations in Serum Than in Plasma
Authors: Rosenthal Robert W , Blackburn Arthur
Published: January 2020

Serum and plasma were analyzed for copper by atomic absorption spectrophotometry. Serum copper values were significantly higher than the corresponding values for plasma. The reasons for this difference are not known.
Total Neutral 17-Ketosteroids
Authors: Kafka Marian S , Bondy Philip K
Published: January 2020

The Masuda and Thuline method for measuring urinary neutral 17-ketosteroids has been modified by substituting polyethylene bottles and a mechanical shaker for separatory funnels and manual shaking, and by developing the color and reading it in the same test tube. Combining Zimmermann reagents before addition eliminates the necessity for frequently pipeting small volumes. The new method permits the analysis of 10 to 15 urines in a single operation without sacrificing accuracy or specificity.
Determination of Sulfobromophthalein in Serum
Authors: Seligson David , Marino Jean , Dodson Elizabeth
Published: January 2020

A method for the determination of BSP is presented which eliminates errors due to protein-binding with albumin and artifacts due to bilirubin, hemoglobin, and turbidity. Measurements at two or three wavelengths are thereby reduced to measurement at one wavelength. The method while simplified appears to be accurate, particularly in the low ranges.
Influence of Variations in Body-Fluid Volumes on Sodium Metabolism in Man
Authors: Josephson Berth
Published: January 2020

A review has been given of recent papers on the influence of acute changes in extracellular, extravascular fluid volume and in plasma volume on the salt metabolism. The influence of intravascular pressure, pitressin, adrenal steroids, etc., has been mentioned. Some work from the author's laboratory has been reported. It was found in this laboratory that a large intravenous infusion-25 ml./min. during 1-2 hours-of iso-oncotic glucose has no influence on sodium excretion in normal man, but that it gives rise to a very high increase of the sodium output in cases of arterial hypertension. Later on it was found that patients with cardiac failure behave as the hypertensive do in this respect. On the other hand, an intravenous infusion of a corresponding amount of iso-oncotic dextran solution gives a considerable decrease of sodium excretion in healthy subjects as well as in patients with the above-mentioned diseases. The correlation between these results and the changes of the kidney function and the renal hemodynamic have been discussed.
A Toxicologic Service in a General Hospital
Authors: Nobel Sidney
Published: January 2020

Information and suggestions found of value in a general hospital in dealing with toxicologic problems are presented. Relevant problems such as good liaison between the emergency room and the laboratory, sources of information on product composition, the preparation of an odor reference shelf, and selection of methods to help meet the majority of situations encountered have been discussed. The importance of participation in public-health education programs has also been indicated.
Chronic Alkalosis with Damage to the Central Nervous System
Authors: Natelson Samuel
Published: January 2020

A condition of chronic alkalosis has been described with central nervous system damage. This syndrome is characterized by alkaline blood pH, and elevated total CO2 levels, associated with central nervous system damage. It is apparently caused by sodium retention as indicated from the sodium to chloride ratios in the urine excreted by these patients. In alkalosis, the output of fluid is often greater than the input. Sodium chloride solutions intravenously tend to aggravate the alkalosis. Potassium chloride or ammonium chloride will relieve the alkalosis only temporarily. Pitressin will not correct the abnormal sodium to chloride ratios in the urine. A carbonic anhydrase inhibitor (Diamox) will lower the CO2 levels, and correct the blood pH. Its action seems to be due to its ability to correct the sodium to chloride ratios in the urine excreted. The effect of Diamox will persist for several days after its administration.
Automatic Pipeting Attachment for the Van Slyke Manometric Apparatus for CO2 Determination
Authors: Seligson David , Marino Jean
Published: January 2020

An automatic pipeting device has been attached to the Van Slyke manometric apparatus for the determination of CO2. It has proved to be accurate, requires a small sample of serum, and is self-cleaning and rapid.
Rapid System of Microchemical Analysis for the Clinical Laboratory
Authors: Saifer Abraham , Gerstenfeld Shirley , Zymaris Michael C
Published: January 2020

A rapid, semiautomatic system of microchemical analysis for the clinical chemistry laboratory has been proposed. Five basic elements of this system are: (1) The use of siliconated-heparinized plasma. (2) The use of the calibrated-pipet-tip buret technic for measuring small (0.10-ml.) samples. (3) The use of the decantation principle as a precision step in making quantitative transfers. (4) The use of automatic syringe pipets for adding constant volumes of reagents, (5) The use of specific enzymatic methods, whenever these are applicable, for the determination of biologic constituents.

The analytic system has already been applied to the determination of such important biologic constituents as glucose, urea nitrogen, phosphorus, acid and alkaline phosphatases, sodium and potassium, calcium, and total protein.

The semiautomatic system permits the use of microprocedures in a clinical chemistry laboratory by persons of limited technical skill.
A Simple Viewer for Prothrombin Determination and Other Coagulation Tests
Authors: Giovanniello Thomas J , Belko John S
Published: January 2020

1. A clot viewer has been described, which is an adaptation of a colony counter and requires little or no money to construct.
The Microbiologic Assay of Vitamins in Clinical Chemistry
Authors: Sobotka Harry
Published: January 2020

The examples which have been given above in the cyanocobalamin and folic acid field illustrate the usefulness of the microbiologic assay of vitamins in investigate work. The application of these methods to routine determinations will follow, once the indications for their usefulness are established. Table 7 summarizes the vitamins for which we have developed assay methods, the microorganisms used, and their sensitivity.

The methods described are much simpler than they may appear to be at first sight, and they require no expensive or special equipment. They can become in due course routine procedures and will contribute to one of the lesser known chapters of clinical chemistry.
Determination of Serum Lipoproteins by Paper Electrophoresis after Preliminary Staining with Sudan Black-B
Authors: Kanabrocki Eugene L , Kaplan Ervin , Kinnory David S , Imperato Alfred A , Berry John E , Baker Lyle A
Published: January 2020

A modification of McDonald's method for the determination of serum lipoproteins is described in which serum is prestained with Sudan Black B dye before paper electrophoretic separation.

Normal values were determined in 24 adults. Average value for α lipoproteins was 39.2 per cent and for β lipoproteins 60.8 per cent. In 31 patients with proved coronary artery disease, 22.7 per cent α lipoprotein and 77.3 per cent β lipoprotein were found. These results are in general agreement with those of other investigators using different methods.
Biological Role of Magnesium
Authors: Pleshchitser A La
Published: January 2020

Fersman (1934) commented on the relatively unimportant role of magnesium in biochemical processes. The comparatively limited radius of its ions, the stability and relative insolubility of its compounds prevent its taking an active part in the reactions of living matter. On the other hand, we have the statement of Vernadskii that in the plankton film of the ocean, in the ordinary accumulations and more massive growths, the amount of magnesium-containing chlorophyll must reach the order of 10-4 per cent by weight, if not higher, so that a small quantity of magnesium, entering into the composition of the chlorophyll-complex of the plankton, ultimately regulates the main part of the oxygenating function of living matter, the creation of free atmospheric oxygen. The material summarized by us likewise affords evidence of the importance of the role of magnesium in biological processes.

All this, however, does not justify sharp differentiation between the biological role of magnesium and its role in biochemical processes. In all probability these processes are conditional to each other, although they are not identical processes.

It is important to note the established and incontestable role of magnesium in many enzymatic processes in both the plant and animal kingdoms.

The antagonistic action between magnesium and calcium, resulting from artificial changes in the ratios of these elements in soil, plants, and animals, can hardly occur under natural conditions, and, conversely, it must be assumed that a labile equilibrium between these elements is always maintained.

The depressing action of magnesium ions on the central nervous system acquires considerable biological significance, since this permits the assumption that these ions in the animal organism may facilitate inhibitory processes in the nerve cell and insure the normal course of catabolic and anabolic processes.

The narcotic and cholinolytic effects of magnesium constitute the basis for the wide therapeutic use of magnesium salts in medical practice.
Pitfalls in measuring plasma cholesterol in the Smith–Lemli–Opitz syndrome
Authors: Jira Petr E , de Jong Jan G N , Janssen-Zijlstra Fokje S M , Wendel Udo , Wevers Ron A
Published: January 2020

Correct quantitative results for plasma cholesterol, 7-dehydrocholesterol (7-DHC), and 8-dehydrocholesterol (8-DHC) are invaluable for making the correct diagnosis in patients with the Smith–Lemli–Opitz syndrome (SLO) and for biochemical monitoring of these patients during therapy. The enzymatic method for cholesterol measurement based on cholesterol oxidase gives falsely high values for plasma cholesterol in samples from patients with SLO. Both 7-DHC and 8-DHC contribute substantially to the test result, given that they are accepted substrates of cholesterol oxidase. All cholesterol methods making use of this enzyme are expected to give unreliable results with plasma samples from SLO patients. Cholesterol values found with these methods may be low-normal in individual cases with SLO. Therefore, other techniques for measuring cholesterol, 7-DHC, and 8-DHC, e.g., gas chromatography, should be used for diagnosing these patients and for follow-up during therapy. However, a normal value for plasma cholesterol, as obtained by gas chromatography, does not exclude SLO. The diagnosis should always be confirmed or excluded by testing for the presence of high concentrations of 7-DHC and 8-DHC in plasma. We found that one patient with a severe form of the disease had a plasma cholesterol concentration of 20 μmol/L—to our knowledge, the lowest value ever recorded in a human being.
Measurement of lactate in cerebrospinal fluid in investigation of inherited metabolic disease
Authors: Hutchesson Andrew , Preece Mary Anne , Gray George , Green Anne
Published: January 2020

Measurement of lactate concentrations in cerebrospinal fluid (CSF) has been suggested as part of the investigation of inborn errors of the electron transport chain, but little information exists regarding the reference range in children or the relationship between CSF and plasma concentrations. In 39 children without bacterial meningitis, diabetes, or recent seizures, we determined that the median (range) lactate concentrations in CSF and plasma collected concurrently were 1.4 (0.8–2.2) and 1.5 (0.6–2.3) mmol/L; the regression equation was CSF lactate = (0.38 ± 0.06) plasma lactate + 0.83 (r2 = 0.14). In 8 of 11 (73%) children with electron transport chain defects, CSF lactate was ≥3.0 mmol/L; however, 2 of these 8 had a normal plasma lactate concentration. CSF lactate was also increased in 2 children with nonketotic hyperglycinemia. The finding that CSF lactate concentrations may be increased despite a normal plasma lactate value in children with electron transport chain defects is an important clue to the diagnosis of these disorders.
Sandwich-type enzyme immunoassay for big endothelin-1 in plasma: concentrations in healthy human subjects unaffected by sex or posture
Authors: Aubin Philippe , Le Brun Gaelle , Moldovan Florina , Villette Jean-Marie , Créminon Christophe , Dumas Jacques , Homyrda Laurence , Soliman Hany , Azizi Michel , Fiet Jean
Published: January 2020

A sandwich-type enzyme immunoassay has been developed for measuring human big endothelin-1 (big ET-1) in human plasma and supernatant fluids from human cell cultures. Big ET-1 is the precursor of endothelin 1 (ET-1), the most potent vasoconstrictor known. A rabbit antibody raised against the big ET-1 COOH-terminus fragment was used as an immobilized antibody (anti-P16). The Fab′ fragment of a monoclonal antibody (1B3) raised against the ET-1 loop fragment was used as the enzyme-labeled antibody, after being coupled to acetylcholinesterase. The lowest detectable value in the assay was 1.2 pg/mL (0.12 pg/well). The assay was highly specific for big ET-1, demonstrating no cross-reactivity with ET-1, <0.4% cross-reactivity with big endothelin-2 (big ET-2), and <0.1% with big endothelin-3 (big ET-3). We used this assay to evaluate the effect of two different postural positions (supine and standing) on plasma big ET-1 concentrations in 11 male and 11 female healthy subjects. Data analysis revealed that neither sex nor body position influenced plasma big ET-1 concentrations. This assay should thus permit the detection of possible variations in plasma concentrations of big ET-1 in certain pathologies and, in association with ET-1 assay, make possible in vitro study of endothelin-converting enzyme activity in cell models. Such studies could clarify the physiological and clinical roles of this family of peptides.
Quantitative polymerase chain reaction for human herpesvirus diagnosis and measurement of Epstein–Barr virus burden in posttransplant lymphoproliferative disorder
Authors: Bai Xin , Hosler Gregory , Rogers Beverly Barton , Dawson D Brian , Scheuermann Richard H
Published: January 2020

Human herpesviruses can cause acute diseases such as chicken pox or mononucleosis, but also may reactivate during immunosuppression and result in severe or life-threatening illnesses such as shingles or lymphoproliferative disorders. We report the development and validation of a quantitative PCR method to measure viral burden for all eight human herpesviruses (HSV1, HSV2, VZV, EBV, CMV, HHV6, HHV7, and KSHV) in patients’ samples. The method uses an internal standard that is coamplified with the viral target, allowing quantification of viral genomes in absolute terms (e.g., viral targets/mL of blood) and ruling out false-negative results. We demonstrate that transplant patients with lymphoproliferative disorder carry an EBV viral burden 3 logs higher than nontransplant patients. EBV titers in transplant patients without a lymphoproliferative disorder are between these values. This quantitative PCR method may aid in differentiating clinically significant vs latent viral burden in immunosuppressed patients.
ELISA determination of soluble urokinase receptor in blood from healthy donors and cancer patients
Authors: Stephens Ross W , Pedersen Anders N , Nielsen Hans Jørgen , Hamers Maria J A G , Høyer-Hansen Gunilla , Rønne Ebbe , Dybkjær Esben , Danø Keld , Brünner Nils
Published: January 2020

Measurement of urokinase receptor (uPAR) in tumor extracts has prognostic value, but assay of the soluble uPAR (suPAR) in peripheral blood may offer wider applications in cancer patient management. A tumor extract uPAR ELISA was modified to eliminate nonspecific plasma protein interference, enabling specific detection of suPAR in plasma and sera with >90% recovery of added calibrator. suPAR concentrations in citrate plasma correlated with sera in 93 healthy blood donors (r = 0.84, P <0.0001), with a median value for both of 1.2 μg/L. The plasma median for 19 advanced breast cancer patients was 2.9 μg/L suPAR, and a similar increase was found for 10 advanced colon cancer patients, consistent with release of suPAR from tumors into blood. Repetitive monitoring of suPAR in cancer patients’ blood may have value in assessment of prognosis and tumor recurrence.
Early assessment of patients with suspected acute myocardial infarction by biochemical monitoring and neural network analysis
Authors: Ellenius Johan , Groth Torgny , Lindahl Bertil , Wallentin Lars
Published: January 2020

Neural network analysis was applied for early diagnosis/exclusion of acute myocardial infarction (AMI), prediction of infarct size, and estimation of “time from onset of infarction.” Eighty-eight patients admitted within 8 h after onset of chest pain were included. Blood samples for measurement of myoglobin, creatine kinase isoform MB, and troponin T were obtained every 30 min during the first 3 h and then after successively longer intervals. Data from 50 patients were used to train a set of neural network components of a decision support system. The performance of the system was evaluated and compared with experienced clinicians for the remaining 38 patients. The computer system detected myocardial infarction and predicted infarct size earlier than the clinicians, but did not differ significantly in terms of diagnostic sensitivity, specificity, and predictive values when disregarding time for diagnosis. With a cross-validation procedure the cumulated sensitivities of the computer system for the first five measurements were estimated to be (mean ± 2SEM, n = 100): 0.77 ± 0.03, 0.89 ± 0.02, 0.94 ± 0.02, 0.97 ± 0.01, and 0.99 ± 0.01, respectively, with corresponding cumulated specificities between 0.93 ± 0.01 and 0.91 ± 0.01. We concluded that neural network analysis of serial measurements of biochemical markers might provide useful support for the early assessment of patients with suspected AMI.
Kinetic assay of serum and urine for urea with use of urease and leucine dehydrogenase
Authors: Morishita Yoshitaka , Nakane Kiyoshi , Fukatsu Toshiaki , Nakashima Nobuo , Tsuji Katsumi , Soya Yoshihiro , Yoneda Keizo , Asano Shigeki , Kawamura Yoshihisa
Published: January 2020

We describe a new kinetic assay for determining urea in serum or urine with use of urease (EC 3.5.1.5) and leucine dehydrogenase (EC 1.4.1.9). The latter enzyme is suitable for the kinetic assay of NH4+ because itsKmvalue for NH4+ at pH 8.75 is large (∼500 mmol/L). Interference from endogenous NH4+ in serum or urine is obviated by subtraction of the assayed endogenous NH4+value in a sample blank. For serum, within-assay CVs (n = 10) were 0.39–0.58%; day-to-day CVs (n = 10) were 1.56–2.30%. In urine, within-assay CVs (n = 10) were 0.86–1.15%. Analytical recovery of urea (0.893–71.4 mmol/L) added to patients’ sera (urea 6.14 mmol/L) was 99.2–105.2%. The calibration curve for serum was linear through zero for urea concentrations up to 142.9 mmol/L and for urine up to 714.3 mmol/L. No influences of added ammonium ion, bilirubin, hemoglobin, ascorbic acid, or Intralipid were observed. The regression equations for this method (y) and conventional methods (x = Determiner-LUN for serum assays, Serotec UUR-R for urine) were: y = 1.016x − 0.12 mmol/L (r = 0.999, Sy|x = 0.34 mmol/L, n = 100) for sera, and y = 1.070x − 12.6 mmol/L (r = 0.998, Sy|x = 7.41 mmol/L, n = 100) for urine.
HLA-B27 phenotyping with flow cytometry: further improvement by multiple monoclonal antibodies
Authors: Hoffmann Johannes J M L , Janssen Willy C M
Published: January 2020

To establish the optimal flow cytometric method for HLA-B27 phenotyping, we compared several strategies, using three monoclonal anti-B27 antibodies (from the HLA-ABC-m3, GS145.2, and FD705 clones). We used a triple-color direct immunofluorescence assay, including a T-lymphocyte-specific antibody as an internal control and an anti-HLA-Bw4 antibody. Blood samples from >400 subjects were tested. From ROC curve analysis none of the three antibodies appeared to be suitable for use as a single typing reagent. The efficiency of the test was affected by cross-reactions with other HLA antigens, notably the HLA-B7 antigen. Preincubation with anti-B7 serum efficiently inhibited this cross-reaction and raised the test efficiency considerably. We concluded that none of the anti-B27 antibodies investigated is suitable for use as a single typing reagent. Additional typing of Bw4 is not valuable, whereas inhibition of cross-reactions due to the B7 antigen will considerably improve the performance of the test. We recommend that two different monoclonal anti-B27 antibodies be used for accurate and reliable HLA-B27 phenotyping with flow cytometry.
Minimizing interferences in the quantitative multielement analysis of trace elements in biological fluids by inductively coupled plasma mass spectrometry
Authors: Hsiung Chiung-Sheng , Andrade Joseph D , Costa Robert , Ash K Owen
Published: January 2020

The determination of trace and ultratrace elements in biological fluids, including urine and serum, by inductively coupled plasma mass spectrometry (ICP-MS) is discussed. Nonspectral interferences and their corrections by external calibration and calibrator addition are discussed in detail. External calibration with internal calibration and dilution is mostly sufficient to correct for encountered biological matrix effects. For some elements, such as Cs and Zn, the use of calibrator addition provides more accurate results. The importance of spectral interferences and their elimination by isotope selection was also studied. Two examples, Cu and Zn, demonstrate the prime importance of selecting an isotope with minimal polyatomic interferences for analysis. By using 65Cu and 68Zn, accurate results for urine and serum can be obtained without excessive pretreatment of samples. Two reference materials, Bio-Rad Lyphochek urine and Kaulson Contox sera, were analyzed. Accuracy was evaluated by comparison with target values, and precision was estimated by the CV within 95% confidence.
7α-Biotinylated testosterone derivatives as tracers for a competitive chemiluminescence immunoassay of testosterone in serum
Authors: Luppa Peter , Brückner Christine , Schwab Ingrid , Hauck Sabine , Schmidmayr Stefan , Birkmayer Christian , Paulus Birgit , Hauptmann Hagen
Published: January 2020

Ring core-biotinylated testosterone tracers were synthesized with bridges of three different lengths connecting the biotin moiety to the steroid core (7α-Cn-Bio-T, n = 3, 6, or 11). Together with a position 7-specific polyclonal anti-testosterone antibody, we used the 7α-C11-Bio-T tracer to develop a novel, labeled-hapten competitive immunoassay for total testosterone in serum. (The C3 and C6 tracers proved to be not suitable for analogous immunoassays.) Enhanced chemiluminescence signal was generated by use of a second immobilized antibody and a streptavidin–horseradish peroxidase conjugate. The measuring range of the assay is 0.2–20.0 nmol/L, linearity of serial dilutions can be demonstrated, the lower detection limit is 0.125 nmol/L, and the interassay imprecisions are 13–16%. Accuracy determinations in mass spectrometry-controlled reference specimens showed a mean recovery of 95%. In addition, the assay shows low cross-reactivities, demonstrating the favorable specificity of the combination of a “nearly native” tracer with a position analog antibody. The optimized steric structure and the long spacer arm of the biotinylated testosterone tracer make this chemiluminescence assay well-suited for measuring total testosterone concentration in serum.
Age-specific distribution of plasma amino acid concentrations in a healthy pediatric population
Authors: Lepage Nathalie , McDonald Nancy , Dallaire Louis , Lambert Marie
Published: January 2020

Reference values were determined for 23 plasma free amino acids from measurements done in 148 healthy children ranging from 0 to 18 years of age. Amino acid analysis was performed by ion-exchange chromatography. We propose a graphic form of presenting the age-specific distribution of plasma amino acid concentrations where the 10th, 50th, and 90th quantiles are illustrated. Although each amino acid possesses its own pattern of distribution, we can identify five different profiles. Nine amino acids (alanine, arginine, asparagine, methionine, ornithine, phenylalanine, proline, threonine, and tyrosine) demonstrate a decrease in their concentrations during the first year of life; their concentrations then tend to increase throughout childhood and adolescence. Nine others (cystine, glutamine, glycine, histidine, isoleucine, leucine, lysine, tryptophan, and valine) show a steady increase throughout infancy, childhood, and adolescence. Five amino acids (aspartic acid, citrulline, glutamic acid, serine, and taurine) do not follow these two common profiles. For the first time, quantile curves are produced to illustrate the age-dependent variation of amino acid concentrations from infancy to adulthood. This alternative way of presenting amino acid concentrations may facilitate the follow-up of patients with inborn errors of amino acid metabolism.
Human prostate-specific glandular kallikrein is expressed as an active and an inactive protein
Authors: Herrala Annakaisa , Kurkela Riitta , Porvari Katja , Isomäki Ritva , Henttu Pirkko , Vihko Pirkko
Published: January 2020

A polymorphism in the human prostate-specific glandular kallikrein (hKLK2) gene was described by direct sequencing (by PCR) of genomic DNAs isolated from prostatic cancer tissue, benign prostatic hyperplasia tissue, and blood leukocyte specimens. Results showed two forms of human prostate-specific glandular kallikrein protein (hK2), a consequence of a change from C to T at base 792 in the hK2 coding region. Producing the two forms as recombinant proteins in insect cells demonstrated that Arg226-hK2 (CC genotype) is an active protein and Trp226-hK2 (TT genotype) is inactive. Polymorphism studies of 36 patients with prostatic diseases identified only 1 with the TT genotype. The same kind of polymorphism was not detected in the human prostate-specific antigen (hKLK3) gene. Arg226-hK2 possessed only trypsin-like enzyme activity, whereas recombinant human prostate-specific antigen (hPSA) had only chymotrypsin-like activity. Monoclonal and polyclonal antibodies raised against hPSA purified from seminal plasma detected both active and inactive hK2. Thus, because inactive as well as stable hK2 protein may be present, a lack of trypsin-like activity in hPSA standards is not enough to confirm that the materials are free of hK2 contamination.
Clinical evaluation of serial blood processing at point of care
Authors: Estey Christopher A , Felder Robin A
Published: January 2020

The Axial Separation Module (ASM™), which separates whole-blood specimens serially in Axial Process Containers (APC™), was evaluated for clinical performance at the University of Virginia Health Sciences Center (UVA HSC) in a community-based outpatient laboratory (North Ridge Clinic). We hypothesized that moving the task of blood separation to point of care would reduce specimen turnaround time within the main laboratory. Blood drawn into an APC was separated in the ASM at point of care at the North Ridge Clinic. Blood drawn into a Vacutainer Tube™was separated in a conventional centrifuge at the main laboratory. Turnaround time was calculated for the “chem 17” test from files stored in our laboratory information system. Blood serially separated at point of care yielded turnaround time savings for specimens originating from the North Ridge Clinic. Average turnaround time decreased by 24%. Phlebotomists found no appreciable workload increase from incorporating the ASM as a point-of-care blood separation device. Phlebotomists also found that they could immediately detect hemolysis. We concluded that serial separation at point of care reduces specimen turnaround time at the main laboratory. The ASM/APC was found to be better suited for point-of-care blood separation than a conventional centrifuge. We speculate that immediate blood separation has the potential to improve the quality of analytical results.
HPLC method for monitoring SDZ PSC 833 in whole blood
Authors: Scott Mitchell G , Hock Karl G , Crimmins Daniel L , Fracasso Paula M
Published: January 2020

P-glycoprotein (Pgp) is a 170-kDa membrane transporter that mediates drug efflux and is an effector of multidrug resistance. SDZ PSC 833 (PSC), a nonimmunosuppressive cyclosporine that potently modulates Pgp, is currently under clinical evaluation in patients with cancer. We have developed a reversed-phase HPLC assay for determining PSC blood concentrations that utilizes a step gradient with linear segments to resolve PSC into two distinct peaks (likely to be keto and enol isomers). To clinically validate the assay, PSC concentrations were obtained by HPLC from nine patients receiving oral doses of 5 mg/kg every 6 h. Values ranged from 0.91 to 5.4 mg/L during the dosing period, comparable with concentrations of PSC that modulate Pgp in vitro. In addition, we investigated the immunoreactivity of the Abbott TDx cyclosporin A (CsA) monoclonal whole-blood assay for PSC. The TDx CsA assay cross-reacts ∼17% with PSC as determined by adding known amounts of PSC to whole blood. When PSC concentrations obtained by the TDx CsA assay were divided by 0.17, we found agreement between the TDx CsA assay and the HPLC PSC assay for samples from nine patients.
Comparative evaluation of three assay systems for automated determination of hemoglobin A1c
Authors: Halwachs-Baumann Gabriele , Katzensteiner Susanne , Schnedl Wolfgang , Pürstner Peter , Pieber Thomas , Wilders-Truschnig Martie
Published: January 2020

We evaluated three newly introduced systems for automated determinations of hemoglobin (Hb) A1c, which allow the processing of large amounts of samples in a routine clinical laboratory. We compared these methods—the Variant HPLC, the Hi-Auto A1c analyzer system, and the Roche immunoassay—with the Diamat HPLC system. All showed good precision and good concordance with the Diamat HPLC. The reference range for Hb A1c has to be determined by the laboratory for each assay system. Interference study showed no statistically significant influence of anemia, polycythemia, rheumatoid factor, or chronic hemodialysis, although individual Hb A1c values can be influenced by polycythemia (when measured with the Hi-Auto A1c analyzer) and by chronic hemodialysis (when measured with the Variant HPLC). HPLC was not suitable for measuring Hb A1c in the examined cases of hemoglobin variants; assaying fructosamine seems to be better for monitoring these patients.
Analysis of a polyadenine tract of the transforming growth factor-β type II receptor gene in colorectal cancers by non-gel-sieving capillary electrophoresis
Authors: Oto Michiei , Koguchi Akira , Yuasa Yasuhito
Published: January 2020

We developed a method to analyze a polyadenine tract, the (A)10 repeat, within the cysteine-rich domain of the transforming growth factor-β (TGF-β) type II receptor gene using a non-gel-sieving capillary electrophoresis technique and applied it to the DNA diagnosis of colorectal cancers. This method consists of single-strand DNA amplification of the (A)10 repeat by an asymmetric PCR technique and capillary electrophoresis. A higher concentration of dATP in the PCR reaction mixture led to more specific amplification of the (A)10 repeat. Under the optimal electrophoretic conditions, one nucleotide difference could be determined in 8 to 32 nucleotides. One or two base deletions of the (A)10 repeat in colorectal cancers could be detected under these conditions within 30 min, and the results coincided with those obtained on DNA sequencing analyses. According to a sensitivity study, we could detect the deleted sequence if it was present in 12.5% or more of the wild-type allele. The reproducibility of this technique was satisfactory because the intraassay imprecision (CV) (n = 10) was 1.4%. These results indicate that capillary electrophoretic analysis of small repeated sequences results in easier handling and more feasible automation, compared with conventional gel electrophoretic analysis.
How many mistakes, how to find them
Authors: Blase Amy B
Published: January 2020

The topic of quality control often evokes prolific discussion among those whose business is its administration. Reliable methods for identifying mistakes must be developed in both the manufacture and use of test devices. Unit test devices are uncomplicated to run and provide quick results in a world where speed and simplicity are paramount, yet their very nature as individual assay units introduces questions about the relevance of conventional quality control procedures. Hybritech’s ICON® QSR® CKMB assay is a unit test device that requires daily monitoring according to CLIA’88 regulations. The challenge is to ensure that quality- control testing is value-added, assuring clinicians valid patient sample results although controls are run in a separate “assay.” We find that conventional quality- control procedures are indeed valid; however, the fundamental difference of unit test devices must be recognized and accounted for by understanding the capability of the assay in each laboratory.
Assessment of a portable clinical blood analyzer during space flight
Authors: Smith Scott M , Davis-Street Janis E , Fontenot Tina B , Lane Helen W
Published: January 2020

This study was designed to validate the utility of a commercial portable clinical blood analyzer (PCBA) in ground-based studies and on the space shuttle. Ionized calcium, pH, electrolytes, glucose, and hematocrit were determined. Results agreed well with those from traditional laboratory methods, and the PCBA demonstrated good between-day precision for all analytes. In-flight analysis of control samples revealed differences in one analyte (sodium). There were few changes in crew members’ results during flight, and these were expected. Potassium increased in flight compared with before flight, and potassium, pH, and hematocrit decreased after flight. Ionized calcium was decreased in flight and on landing day. Changes during flight were likely related to sample collection technique. Postflight changes likely reflected the fluid redistribution that occurs after exposure to weightlessness. These data confirm that the PCBA is a reliable instrument for most analytes, and can provide important medical data in remote locations, such as orbiting spacecraft.
Diagnostic strategies and test algorithms in liver disease
Authors: Black Edgar R
Published: January 2020

As clinicians evaluate patients, they first develop problem lists based on the history, physical examination, and basic laboratory studies. Synthesis and analysis result in a differential diagnosis with associated disease probabilities. Experienced clinicians then selectively use diagnostic tests to rule in or rule out these possibilities. For example, in a patient presenting with jaundice, anorexia, fever, and abdominal pain, the relative increases of the serum aminotransferase activity and the serum alkaline phosphatase will help to guide the subsequent evaluation. If the aminotransferase activity is markedly increased, then the subsequent evaluation will be targeted toward identifying an etiology for hepatocellular injury. In contrast, if the alkaline phosphatase is markedly increased, then the evaluation would be targeted toward identifying an etiology for obstructive jaundice. This paper reviews clinical decision making, discusses characteristics of diagnostic tests, and presents examples of how basic clinical information can guide the use of the laboratory in evaluating patients with suspected liver disease.
Serum concentrations of carboxyl-terminal propeptide of type I procollagen, amino-terminal propeptide of type III procollagen, cross-linked carboxyl-terminal telopeptide of type I collagen, and their interrelationships in schoolchildren
Authors: Crofton Patricia M , Wade Jean C , Taylor Mervyn R H , Holland Celia V
Published: January 2020

We report pediatric age- and sex-specific 95% reference intervals for procollagen type I C-terminal propeptide (PICP), the cross-linked C-terminal telopeptide of type I collagen (ICTP), and procollagen type III N-terminal propeptide (P3NP), measured in plasma from 302 schoolchildren (156 boys, 146 girls) ages 4–19 years. All three markers displayed a significant variation with age (ANOVA P ≤0.0015). PICP showed no detectable increase during adolescence for either sex, but decreased towards adult concentrations after the age of puberty, with an earlier decrease for girls than for boys (P <0.01). ICTP and P3NP both increased in pubertal-aged children (P <0.05), with an earlier increase in girls than in boys (P <0.05), before decreasing towards adult concentrations (P <0.01). All three collagen markers were highly correlated with one another (P <0.001). The patterns observed mirrored the childhood growth curve and reflected the high turnover of bone and soft tissue during childhood growth.
Thiocyanate in smokers interferes with the Nova magnesium ion-selective electrode
Authors: Rehak Nadja N , Cecco Stacey A , Niemela Julie E , Elin Ronald J
Published: January 2020

Thiocyanate found in serum ordinarily is the metabolite of cyanide that is inhaled with tobacco smoke and ingested with cyanogenic foods. We investigated the effect of the thiocyanate ion (SCN−) on the ionized magnesium (iMg) and ionized calcium (iCa) results determined with the AVL and Nova magnesium and calcium ion-selective electrodes (ISEs). We analyzed saline and pooled serum with added SCN−, and serum from apparently healthy nonsmokers (n = 20) and smokers (n = 20). The mean (and range) of the measured serum SCN− concentration was 0.019 (0.008–0.046) mmol/L for nonsmokers and 0.077 (0.020–0.138) mmol/L for smokers. Only the Nova iMg results decreased with increasing SCN−concentration, and the change was dependent on the baseline iMg concentration. In the absence of Mg, SCN− decreased the voltage response of the Nova Mg ISE to calcium ions. At apparently normal serum iMg and iCa concentrations, the interference by SCN− appeared to be equimolar (iMg = −1.04 × SCN− + 0.52). Thus, the serum SCN− commonly found in smokers causes a significant (P <0.0001) decrease in the Nova iMg results.