bluuebunny/crossref_metadata_2025 huggingface dataset:
Total and direct-reacting bilirubin values by automated methods compared with liquid chromatography and with manual methods for determining delta bilirubin
Authors: Rosenthal P , Keefe M T , Henton D , Cheng M , Lee C R , Hall R L , Newton M K
Published: January 2020

This study compares total and direct-reacting bilirubin values in 40 serum samples from patients with various diagnoses, as measured by automated methods (Beckman Synchron CX-5, Beckman Astra 8, Kodak Ektachem 700) and HPLC and by a manual method for delta bilirubin. For total bilirubin, within-run CVs were less than 6%. The Ektachem 700 method underestimated bilirubin with serum samples from patients with Crigler-Najjar syndrome and from newborns in whom unconjugated bilirubin concentrations were increased but conjugated bilirubins were not present or were present only in small amounts. The Astra 8 and Synchron CX-5 methods were inaccurate with cholestatic serum samples, in which conjugated bilirubin concentrations were increased and other compounds such as bile acids could be expected to interfere. We conclude that each automated method examined provides reasonable estimates for total and direct-reacting bilirubin values for routine clinical use. The need for each laboratory to select the appropriate bilirubin method for its particular situation is obvious.
Variant acute intermittent porphyria in a child
Authors: Badcock N R , Zoanetti G D , O'Reilly D A , Robertson E F
Published: January 2020

A child who was grossly malnourished and who showed increased excretion of porphyrin and porphyrin precursor had normal activity of erythrocyte porphobilinogen deaminase (EC 4.3.1.8) and leukocyte protoporphyrinogen oxidase (EC 1.3.3.4). Clinical symptoms, coincident with the excretion of rose-colored urine, were consistent with the diagnosis of an acute porphyria. The disease resolved spontaneously after the withdrawal of carbamazepine and sodium valproate and the commencement of parenteral nutrition with subsequent carbohydrate loading. In addition to normal concentrations of enzyme activities, the patient is unusual in presenting before puberty and in having no family history of porphyria.
Desialylated transferrin and mitochondrial aspartate aminotransferase compared as laboratory markers of excessive alcohol consumption
Authors: Kwoh-Gain I , Fletcher L M , Price J , Powell L W , Halliday J W
Published: January 2020

Concentrations of both desialylated transferrin (dTf) and the mitochondrial isoenzyme of aspartate aminotransferase (EC 2.6.1.1, mAST) have been claimed to be increased in sera of alcoholic subjects. To investigate the diagnostic usefulness of these new biochemical markers of alcoholism and to compare them with more conventional markers, we measured dTf and mAST in the sera of controls, alcoholic subjects, and patients with nonalcoholic liver diseases (NALD). Alcoholic subjects had significantly (P less than 0.001) higher ratios of dTf to total transferrin than did either healthy controls or patients with NALD (sensitivity 81%, specificity 97%). The mAST was increased in 92% of alcoholic subjects but also in 48% of patients with NALD. The mAST/total AST ratio differentiated the alcoholic subjects from those with NALD (P less than 0.001) with a sensitivity of 92%, but the specificity was only 70%. In contrast, the conventional markers were less sensitive and less specific. We conclude that the best available single laboratory marker for current heavy alcohol consumption is the ratio dTf/total transferrin.
Urinary excretion of cyclohexanediol, a metabolite of the solvent cyclohexanone, by infants in a special care unit
Authors: Mills G A , Walker V
Published: January 2020

Using gas chromatography-mass spectrometry, we investigated the urinary excretion of organic acids of 278 newborn babies in a special care unit to obtain reference data and monitor metabolism. In 101 of 584 urine samples analyzed, we found isomers of cyclohexanediol. trans-1,2-Cyclohexanediol was always most abundant, with small amounts of 1,3- and 1,4-cyclohexanediol and, sometimes, traces of cis-1,2-cyclohexanediol. Glucuronide conjugates were not detected. The probable source was the solvent cyclohexanone, which was found as a contaminant of intravenous dextrose and the parenteral feeding solution, and was also leached into the infusion fluids from the administration set. We recovered 0.89 mg (range 0.74-0.98 mg, n = 5) of cyclohexanone from 150 mL of dextrose pumped through the infusion apparatus over 24 h, the normal rate for a 1-kg premature baby. Although this is well below toxic doses reported for mature animals, more data are needed for the newborn, particularly preterm infants who have a decreased capacity for glucuronide conjugation.
Improved radioassay of anti-acetylcholine receptor antibody: application for the detection of extremely low antibody titers in sera from patients with myasthenia gravis
Authors: Ohta M , Ohta K , Mori F , Itoh N , Nishitani H , Hayashi K
Published: January 2020

We examined sera from 113 patients with myasthenia gravis (MG). Most of the patients with ocular MG without thymoma and 15% of the patients with generalized MG had immunoprecipitation (IP) titers of anti-acetylcholine receptor (anti-AChR) antibodies within the normal range for healthy subjects. We developed a highly sensitive radioassay using Staphylococcus aureus cells, and re-examined the 86 serum samples that had negative titers by IP. Using the radioassay, we detected anti-AChR antibodies in 27 (31%) of these myasthenic sera, of which 19 were from ocular MG patients without thymoma. By combining the standard IP assay and our new radioassay, we increased to 50% the overall percent positivity of detecting nonblocking-type antibodies in ocular MG patients without thymoma. We detected no anti-AChR antibodies in nearly all patients with various immunological and neurological diseases other than MG, and in all the healthy controls. The data for these sera indicate that in some cases the standard IP assay gives false-negative reactions. Thus, use of the more sensitive radioassay is preferable for accuracy.
Time-related changes in the diagnostic utility of total lactate dehydrogenase, lactate dehydrogenase isoenzyme-1, and two lactate dehydrogenase isoenzyme-1 ratios in serum after myocardial infarction
Authors: Galbraith L V , Leung F Y , Jablonsky G , Henderson A R
Published: January 2020

Using receiver-operating characteristic (ROC) curve and likelihood ratio analysis, we examined the diagnostic utility of total lactate dehydrogenase (LD; EC 1.1.1.27) activity (I). LD isoenzyme-1 activity (II), and the LD-1 percentage of total LD activity (III), LD-1 LD-2 (IV), and LD-1/LD-4 (V) in 347 persons admitted to the Cardiac Care Unit (of whom 173 were subsequently proven to have had myocardial infarction). Blood was sampled from these subjects at about 6-h intervals for up to 96 h from the onset of chest pain. Defining an "effective" test as one having an area under the ROC curve of greater than or equal to 0.9, we determined the ranked utility (greatest to least) of these tests as V = IV greater than III greater than II greater than I. Tests III, IV, and V had by this criterion, diagnostic effectiveness equivalent to measurements of creatine kinase-2 in serum but in samples obtained at later time intervals. The decision thresholds for both high (constant) test sensitivity and specificity varied with time, to differing extents, over the entire 96-h period, a finding with important diagnostic implications. We document positive and negative likelihood ratio values for each of these tests throughout the entire period of study.
Coupled-enzyme determination of catalase activity in erythrocytes
Authors: Van Lente F , Pepoy M
Published: January 2020

This coupled-enzyme method for determining the activity of catalase (EC 1.11.1.6) in erythrocyte lysates is based on measuring the absorbance at 340 nm of NADH produced from the peroxidic reaction between ethanol, hydrogen peroxide, and catalase. Hydrogen peroxide is produced as a substrate in situ from the oxidation of glucose catalyzed by glucose oxidase (EC 1.1.3.4). Catalase oxidizes ethanol to acetaldehyde in the presence of hydrogen peroxide. Acetaldehyde is then oxidized by aldehyde dehydrogenase (EC 1.2.1.5) to produce acetate with concomitant conversion of NAD+ to NADH. The reaction did not follow strict zero-order kinetics; enzyme activity was quantified by using initial rates and standards prepared from purified catalase. The method demonstrated within-run and between-run CVs of 1.0% to 2.9% and 2.4% to 3.3%, respectively. This semiautomated method correlated well (r = 0.92) with the more tedious manual method involving measurement at 240 nm.
Interference in an automated radial partition fluorescent immunoassay of thyrotropin associated with liver-function abnormalities
Authors: Sacks D B , Lim M M , Parvin C A , Kessler G
Published: January 2020

In a previous evaluation of a "sensitive" radial partition fluorescent immunoassay on the Stratus system, thyrotropin (TSH) values exhibited a positive bias in icteric samples when compared with results of a nonsensitive radioimmunoassay. In the present study, we evaluated 366 patients samples to assess whether any biochemical markers of liver function could identify samples for which TSH values would be falsely increased. gamma-Glutamyltransferase and total bilirubin concentrations were unrelated to discrepant TSH values. In contrast, alkaline phosphatase (ALP) was significantly positively correlated with differences in Stratus and RIA TSH concentrations (P less than 0.001). However, this correlation explained only 34% of the observed residual variability around the estimated regression line. On average, the higher ALP values were associated with larger discrepancies between Stratus and RIA TSH values, although several samples with increased ALP did not have falsely increased Stratus TSH values. TSH measurements performed with a Stratus should be interpreted with caution in patients with abnormal biochemical markers of liver function.
A simple method for estimating association constants between monoclonal antibodies and derivatized or native antigens
Authors: Schramm W , Yang T , Meyerhoff M E , Bachas L G
Published: January 2020

We describe a simple method for estimating the association constant between an antibody and an antigen, based on a theoretical treatment of experimental dose-response data. We used this method to calculate the association constants of an anti-progesterone monoclonal antibody for native progesterone and for progesterone 11 alpha-hemisuccinate. These association constants provide a quantitative measure of the bridging-group recognition by the antibody.
Identification of an ascorbic acid metabolite among "uremic middle molecules"
Authors: Gallice P M , Monti J P , Braguer D L , Monti H M , Elsen R E , Berland Y F , Crevat A D
Published: January 2020

Among uremic toxins in the middle molecular mass range, 1H, 13C-nuclear magnetic resonance, ultraviolet spectrometry, and chromatographic analyses allow identification of the main component of the so-called "2-5-3 fraction" as ascorbic acid 2-sulfate, a conjugated metabolite of ascorbic acid. We previously (Clin Nephrol 1986;25:212-8) showed an inhibitory effect of the 2-5-3 fraction on microtubule formation. Therefore, we tested the action of ascorbic acid 2-sulfate and its synthetized enantiomers on tubulin polymerization. Because these molecules did not exert any inhibitory effect, we hypothesize that the 2-5-3 fraction is a mixture of compounds in which only a very low quantity of the inhibitory factor is present.
Ethics and Laboratory Medicine
Authors: McQueen Matthew J
Published: January 2020

Ethical issues have been given limited attention by professionals in laboratory medicine. Professional ethics is the moral bond that links a profession, the people it serves, and society. Understanding the complexities of individual and common good is essential for full professional participation in major issues in health care. Specific issues that challenge laboratory professionals in clinical research are allocation of health-care resources, testing conducted nearer the patient, confidentiality, screening tests, and molecular biology. A voice in ethical issues is an essential element of professional independence. The ethical attitudes we display influence the kind of people who choose to work in our profession. More open discussion about ethics is necessary in our professional literature.
A Decade of Development in Immunoassay Methodology
Authors: Gosling James P
Published: January 2020

Immunoassays are now very widely used in the clinical laboratory, either because no other type of assay system is feasible or because they are often the most effective and suitable of the possible analytical methods. The last decade has seen the development and refinement of many new immunoassay reagents and systems. The major trend has been away from liquid-phase assays involving radioisotopic labels, towards fast homogeneous or solid-phase assays capable of operation anywhere; and towards precise and reliable nonisotopic, automated or semi-automated laboratory assays, often with detection limits measured in pico- or attomoles. The use of monoclonal antibodies is now widespread, and the methodologies of labels and of solid-phase components are much more sophisticated. New assay formulations, novel homogeneous systems, immunosensors, free-analyte assays, the importance of thorough validation and of interfering substances, and future trends are discussed.
Differential electroimmunoassay of human LpA-I lipoprotein particles on ready-to-use plates
Authors: Parra H J , Mezdour H , Ghalim N , Bard J M , Fruchart J C
Published: January 2020

We describe a method for directly measuring LpA-I lipoprotein particles containing apolipoprotein A-I (apo A-I) not associated with apolipoprotein A-II (apo A-II), by differential electroimmunoassay of plasma on ready-to-use plates. Lipoprotein particles containing both apo A-I and apo A-II (LpA-I:A-II) are retained close to the wells when a very high excess of anti-apo A-II is used as compared with anti-apo A-I, whereas the LpA-I particles migrate and react with anti-apo A-I. The method is specific, rapid, and precise. Within- and between-run CVs at three concentrations (high, medium, and low) ranged between 1.51% and 2.72% and 3.01% and 4.56%, respectively. Analytical recovery of isolated LpA-I was from 93% to 115%. Results correlate well with those obtained by two-phase electroimmunoassay, enzyme-linked differential-antibody immunosorbent assay, and immunoaffinity chromatography coupled to enzyme-linked immunosorbent assay. The average normolipidemic concentration of LpA-I was 600 mg/L in 45 women and 490 mg/L in 40 men (P less than 0.0001).
Prostatic Acid Phosphatase in Serum of Patients with Prostatic Cancer Is a Specific Phosphotyrosine Acid Phosphatase
Authors: Nguyen Linh , Chapdelaine Alcide , Chevalier Simone
Published: January 2020

We developed an assay to measure at acid pH the phosphotyrosine phosphatase activity in sera from patients with prostatic cancer. The method used quantifies the inorganic phosphate liberated from phosphotyrosine after incubation with serum, followed by the deproteinization of the reaction mixture. A high acid phosphatase (EC 3.1.3.2) activity towards phosphotyrosine was observed in all sera from patients with increased activity of prostatic acid phosphatase. This activity represented 96% of prostatic acid phosphatase and 77% of total acid phosphatase activities. Moreover, it was correlated (r = 0.91) with the amount of serum prostatic acid phosphatase determined by radioimmunoassay. When serum acid phosphatase activity was measured on several phosphorylated substrates, preferential hydrolysis was demonstrated for those in which the phosphate group was esterified on an aromatic ring rather than those presenting an aliphatic chain. Among phosphoamino acids, only phosphotyrosine was a good substrate, with little or no activity observed with phosphoserine and phosphothreonine. Human seminal plasma and partially purified prostatic acid phosphatase, tested for their activity on some of these substrates, gave similar results. On the other hand, sera from patients with above-normal alkaline phosphatase activity and no prostatic disease showed little or no activity on phosphotyrosine at both acid and alkaline pH values. Evidence is presented that the prostatic acid phosphatase in serum is a specific phosphotyrosine acid phosphatase.
Use of zinc protoporphyrin in screening individuals for exposure to lead
Authors: Zwennis W C , Franssen A C , Wijnans M J
Published: January 2020

We studied the relation between the concentrations of lead in blood (PbB) and zinc protoporphyrin in blood (ZPP) in a group of 801 men occupationally exposed for more than one year to lead or inorganic lead compounds. Linear regression of PbB on log ZPP provided 95% tolerance intervals for PbB values for a given ZPP value. The intervals we found are too large to warrant the estimation of PbB on the basis of ZPP measurements in health surveillance of lead workers. Instead we propose a procedure in which ZPP can be used as an indicator to decide which individuals exposed to lead need further investigation of PbB in light of existing limit values for PbB. The procedure is applicable only for PbB values of 2.4 mumol/L or more but may reduce considerably the costs for screening individuals or groups of people exposed to lead.
Critical appraisal of two methods for determining aluminum in blood samples
Authors: Hewitt C D , Winborne K , Margrey D , Nicholson J R , Savory M G , Savory J , Wills M R
Published: January 2020

We report two methods for determining aluminum concentrations in blood. Method 1, proposed for routine monitoring of patients with chronic renal failure, includes a collection procedure that can be adopted by any renal dialysis unit, with a minimum of sample contamination. Plasma samples are diluted fourfold with HNO3/Triton X-100 matrix modifier. Method 2 is proposed for determining aluminum concentrations in patients with normal renal function, e.g., in drug studies and environmental monitoring. Samples are diluted with an equal volume of Mg(NO3)2 matrix modifier and atomized from a L'vov platform. By either method, analytical recovery of aluminum added to serum ranged between 92% and 105% throughout the linear calibration range. The reference interval (mean +/- SD) for aluminum in 22 healthy subjects by method 2 was 0.044 +/- 0.030 mumol/L.
Cross-correlation of cyclosporine concentrations and biochemical measures of kidney and liver function in heart and heart-lung transplant recipients
Authors: Trull A , Hue K , Tan K , Gore S , Whitewood S , Smyth R , Scott J , Price C , Wallwork J
Published: January 2020

Cross-correlation of cyclosporine concentrations with results of biochemical tests of renal and liver function, measured during the first three months post-operatively, was carried out retrospectively in 24 heart and eight heart-lung transplant recipients to assess the temporal relationship between cyclosporine treatment and the development of possible toxic side-effects. We found a statistically significant negative correlation (95% confidence interval of the mean correlation coefficient did not overlap zero) between the five-day mean concentration of cyclosporine in whole blood (but not plasma) as measured with nonselective (NSRIA) and selective radioimmunoassays (SRIA) and the mean reciprocal creatinine concentration measured in the subsequent five days. In 15 of 32 (47%) patients the negative correlation coefficient exceeded 0.7 (high susceptibility), whereas in 11 of 32 (34%) it was between 0.5 and 0.7 (medium susceptibility), and in only six of 32 (19%) was it less than 0.3 (low susceptibility). We found no consistent correlations between cyclosporine measurements and results of other renal-function tests or liver-function tests. This suggests that therapeutic doses of the drug are not hepatotoxic in most patients. There was, however, a significantly correlated decrease in the NSRIA/SRIA ratio and in serum bilirubin concentration with time post-operatively, reflecting improvement in hepatic function and clearance of the cyclosporine metabolites that are detected by NSRIA. Assays of cyclosporine in whole blood, but not in plasma, are of value in anticipating changes in renal function after heart and heart-lung transplantation.
Consensus Document: Hawk's Cay Meeting on Therapeutic Drug Monitoring of Cyclosporine
Authors: Kahan Barry D , Shaw Leslie M , Holt David , Grevel Joachim , Johnston Atholl
Published: January 2020

The optimal measurement method and clinical application of the therapeutic drug monitoring of cyclosporine remain uncertain (1,2). At a workshop held at Hawks Cay, FL, from January 14 to January 17, 1990, 57 scientists presented their latest research findings, either in formal papers or as discussants. Lively debate and discussion followed presentation of extant and new methodologies for drug measurements as well as multicenter validation studies; applications of trough-concentration monitoring in renal, hepatic, and bone-marrow transplants as well as in autoimmune disease; and alternative pharmacokinetic approaches to guide cyclosporine therapy. The process of inducing and maintaining optimal immunosuppression to facilitate graft success is a complex and often challenging task, requiring the combined expertise of multiple disciplines. Thus, the assembly of four of the groups essential to the transplant process—clinicians, laboratory scientists, the pharmaceutical company, and the manufacturers of cyclosporine measurement kits—provided a unique opportunity to evaluate therapeutic drug monitoring issues facing the transplant field. Here we present the major conclusions reached at the meeting, brief discussions of the study data on which they are based, and a summary of unresolved problems that will require further rigorous investigations. The Consensus Document was reviewed by all the workshop participants before we submitted this final manuscript.
Physiology of blood flow and oxygen utilization by peripheral tissue in circulatory shock
Authors: Rackow E C , Weil M H
Published: January 2020

The primary defect that characterizes circulatory shock is acute perfusion failure, in which oxygen metabolism is critically impaired by decreased delivery of oxygen to tissues. Four categories of hemodynamic deficits are described as the basic mechanisms of circulatory shock: hypovolemia, cardiac failure, distributive deficits, and vascular obstruction. Perfusion failure can be identified by the development of lactic acidosis, because anaerobic metabolism is the consequence of the oxygen deficit during circulatory failure. Lactic acidosis at present represents the best single objective measure of the severity of shock.
Current analytical approaches to measuring blood analytes
Authors: Burritt M F
Published: January 2020

In recent years, laboratory testing in the critical-care setting has increased, a trend due, in part, to the evolution of electrochemical sensors. Various innovations have extended sensor lifetimes, reduced sensor maintenance, and led to the development of single-use and unit-use disposable sensors. These sensor technologies allow the accurate and precise determination, either at or near the bedside, of several analytes including pO2, pCO2, pH, Na, K, Cl, ionized calcium, hematocrit, total hemoglobin, and glucose. Use of these new systems, however, has raised new issues regarding sensor calibration and sample handling and collection. The number of direct-reading analyzers for electrolyte determinations has also increased dramatically. Issues regarding calibration of ion-selective electrodes (ISEs) for Na/K have also been raised after demonstrations of between-instrument variation. Recently, collaborative efforts between eight ISE instrument manufacturers and the National Institute of Standards and Technology resulted in the development of a Standard Reference Material, SRM 956, for the purpose of standardizing direct-reading Na/K ISEs to the flame photometer. Other widely used technologies that provide noninvasive, continuous monitoring include pulse oximetry and transcutaneous gas electrodes. These trends are expected to continue and to produce a new generation of electrochemical and optical sensors.
Through a glass darkly: the lung as a window to monitor oxygen consumption, energy metabolism, and severity of critical illness
Authors: Siegel J H
Published: January 2020

Medical diagnosis and therapeutic monitoring for critical illness require adaptation of laboratory analyses to the bedside. These are greatly helped by the modification of physiological and biochemical data-acquisition techniques to increase the number and accuracy of noninvasive variables that can be obtained from the patient. This paper addresses the choice of noninvasive measurements and is largely directed at the assessment of oxygen debt as a measure of the severity of ischemic and septic metabolic processes. Especially considered are those noninvasive measures of cardiorespiratory adequacy, key variables that need to be considered together with the metabolic function to adequately reflect the patient's state of accommodation to critical illness or injury. I describe a noninvasive sensor system linked to a computer work-station that functions in a pattern recognition mode to permit classification of patients as to the type and severity of their physiological adaptation. This system can serve as a sophisticated bedside monitor of the severity of the patient's condition, as a guide to therapy.
Orchestrating a dignified death in the intensive-care unit
Authors: Youngner S J
Published: January 2020

Approximately 2 million people die in the United States each year, 80% of them in acute- or chronic-care institutions. Physicians now have at their disposal interventions that can postpone death in almost every instance. In these circumstances the critical-care physician cannot avoid the responsibility of orchestrating death by balancing factors such as the patient's autonomy and best interests, medical uncertainty and futility, and notions of "passive" (permissible) and "active" (forbidden) euthanasia. Pressures to make decisions unilaterally and without patient input threaten to undermine important physician/patient/family dialogue. On the other hand, the fact that medical resources are becoming increasingly expensive and scarce will inevitably lead to rationing. The critical-care physician will be caught in the middle--orchestrating clinical care to balance the interests of individual patients and families against those of the larger community.
Robotic transportation
Authors: Lob W S
Published: January 2020

Mobile robots perform fetch-and-carry tasks autonomously. An intelligent, sensor-equipped mobile robot does not require dedicated pathways or extensive facility modification. In the hospital, mobile robots can be used to carry specimens, pharmaceuticals, meals, etc. between supply centers, patient areas, and laboratories. The HelpMate (Transitions Research Corp.) mobile robot was developed specifically for hospital environments. To reach a desired destination, Help-Mate navigates with an on-board computer that continuously polls a suite of sensors, matches the sensor data against a pre-programmed map of the environment, and issues drive commands and path corrections. A sender operates the robot with a user-friendly menu that prompts for payload insertion and desired destination(s). Upon arrival at its selected destination, the robot prompts the recipient for a security code or physical key and awaits acknowledgement of payload removal. In the future, the integration of HelpMate with robot manipulators, test equipment, and central institutional information systems will open new applications in more localized areas and should help overcome difficulties in filling transport staff positions.
Laboratory robotics and artificial intelligence
Authors: Isenhour T L , Marshall J C
Published: January 2020

Intelligent robots, which incorporate artificial intelligence in their controlling software, are the next step in bringing the laboratory robot to its full potential. The areas currently under study in our laboratory are improved user interfaces for laboratory robotics, the integration of object-oriented databases into robot control programs, and strategies to optimize multi-step procedures. The ultimate goal of this work is the Standard Robotics Method. The Standard Robotics Method we envision would allow a robotic method to be transferred from one laboratory to another.
A standard clinical instrument interface for robotic applications
Authors: Margrey K S , Martinez A , Vaughn D P , Felder R A
Published: January 2020

Many clinical laboratory instruments are not designed for robotic compatibility, hence the need for standardization of data communications and analyzer interface hardware. We developed an interface with supporting software that simplifies communication between a microcomputer and clinical instruments. Our interface establishes a standardized bidirectional communications protocol, which is useful in many clinical laboratory robotic projects. Instruments targeted for interfacing require no prior on-board communications capabilities. Additionally, modifications to the clinical instrument are minimized. Once installed, the interface translates input commands to codes or actions recognizable by the analyzer. Features not normally available to the user, such as electrode real-time response and full instrument status, are also reported by the interface, thereby establishing a remote monitor and control mechanism for the interfaced instrument. We have written an operating system to control the interface microcomputer, which in turn commands and monitors the clinical analyzer. A host computer controls the information flow to the interface and provides (a) requests to the interface for instrument operation and status and (b) commands to the interface to initiate the desired instrument operation. This arrangement maintains complete instrument functionality as designed by the manufacturer while allowing remote monitoring and operation of the instrument.
Characterization and rapid diagnostic analysis of DNA polymorphisms closely linked to the cystic fibrosis locus
Authors: Horn G T , Richards B , Merrill J J , Klinger K W
Published: January 2020

Six genetic polymorphisms, closely linked to the cystic fibrosis gene and useful in clinical linkage analysis, have been characterized and converted to a more rapid form of assay. Sequences flanking the metD (Ban I), metH (Msp I), XV-2c (Taq I), KM.19 (Pst I), MP6d-9 (Msp I), and J3.11 (Msp I) polymorphic restriction sites have been determined and used to design specific polymerase chain reaction (PCR) amplification primers and allele-specific oligonucleotide probes. All six of these polymorphisms were found to involve single-base alterations, and the XV-2c polymorphism was found to lie within an Alu repeat segment. These PCR-based tests, in conjunction with the CS.7 (Hha I) assay described elsewhere (Stanier P et al. Hum Genet 1988;80:309-10; Williams C et al. Lancet 1988;ii:102-3), provide a convenient, rapid, and reliable method of haplotype and linkage analysis, clinically useful in those situations where direct detection of mutations is not possible.
Measurement of serum bone gla-protein (BGP) in humans with an ovine BGP-based radioimmunoassay
Authors: Pastoureau P , Delmas P D
Published: January 2020

Most RIAs of serum bone gla-protein (BGP; also called osteocalcin) used for clinical investigation are based on bovine BGP for standard, tracer, and immunogen because of the homology between bovine and human BGP. However, ovine BGP differs from human BGP by only five amino acids, being identical from residues 11 to 49, as compared with homology at residues 20-49 between bovine and human BGP. In screening various anti-ovine BGP polyclonal anti-sera we selected one (R310) that exhibits apparently complete cross-reactivity with human BGP, as assessed by dilutions of 13 human sera from normal subjects and from patients with bone disease. This RIA gave a 42% binding at a 10,000-fold final dilution, with intra- and interassay variations less than 7% and 11%, respectively. Gel-filtration chromatography of human serum showed a single immunoreactive peak. Synthetic fragments of human BGP 1-10, 7-19, 25-37, and 37-49 were not recognized by R310, suggesting that either a mid-molecule region or a conformational epitope was its target. Using this RIA, we determined that serum BGP increased with age in women (P less than 0.02), by a mean of 90% from ages 30 to 70 years. Serum BGP was also increased in patients with primary hyperparathyroidism, renal osteodystrophy, and Paget's disease. In contrast with the "normal" concentrations of BGP detected with an anti-bovine BGP antiserum (R102), serum BGP was increased in patients with postmenopausal osteoporosis as measured with the R310 ovine assay, suggesting a greater sensitivity for the latter assay.
Effect of reticulocytosis on lactate dehydrogenase isoenzyme distribution in serum: in vivo and in vitro studies
Authors: Kazmierczak S C , Castellani W J , Van Lente F , Hodges E D , Udis B
Published: January 2020

We investigated the effect of reticulocytosis on the lactate dehydrogenase (LD; EC 1.1.1.27) isoenzyme LD1/LD2 ratio in patients with and without evidence of hemolytic disease. Analysis of sera from patients with reticulocytosis and in vivo hemolysis showed a mean LD1/LD2 ratio of 0.92 compared with a ratio of 0.69 in patients with in vivo hemolysis and normal reticulocyte counts. Determination of LD isoenzymes in erythrocyte lysate revealed significantly increased LD1/LD2 ratios for patients with marked reticulocytosis compared with those for patients with normal-to-minimal increases in reticulocytes. Finally, separation of mature erythrocytes and reticulocytes by flow cytometry revealed marked differences in the LD1/LD2 isoenzyme distribution between these two cell types. The ability of hemolysis to cause a "flipped" LD1/LD2 ratio is dependent on the proportion of the hemolyzed cells that are reticulocytes.
Electrode measurement of glucose and urea in undiluted samples
Authors: Gourmelin Y , Gouget B , Truchaud A
Published: January 2020

The development of ion-selective electrodes (ISEs) for electrolyte measurements necessitates a re-evaluation of the biological and clinical interpretation of a result. In pathological situations (e.g., hyperlipidemia and hyperproteinemia) direct potentiometry is the method of choice for ion measurements in blood. However, the "plasma water effect" exists also in normal samples, requiring new reference values for physiological ranges. A compromise between medical and instrumentation workers retained the old reference values (flame photometry for Na+ and K+) by introducing correction factors into the ISE instruments, so that the results for direct ISE and flame photometry are the same for "normal" samples. Analyses of "abnormal" samples will reveal biases between the two methods. Now, a new generation of electrodes for assaying additional metabolites reopens the issue. Although classical methods measure a quantity of substance in a predetermined volume of sample, the majority of the substance is usually in the aqueous phase, and the volumes occupied by lipid and protein are not taken into consideration. In evaluating the NOVA 12 instrument (NOVA Biomedical), using electrodes for direct measurement in serum or plasma of Na, K, Cl, total CO2, urea, and glucose, we have demonstrated the inadequacy of classical measurements of urea and glucose, especially in pathological situations characterized by a large variation in the plasma water fraction.
Molar absorptivities of bilirubin (NIST SRM 916a) and its neutral and alkaline azopigments
Authors: Doumas B T , Perry B W , McComb R B , Kessner A , Vader H L , Vink K L , Koedam J C , Paule R C
Published: January 2020

Three laboratories in the U.S. and two in the Netherlands determined molar absorptivities (epsilon) of Standard Reference Material (SRM) 916a Bilirubin from the National Institute of Standards and Technology. In caffeine reagent the average epsilon values were 50,060 and 48, 980 L.mol-1.cm-1 at 432 and 457 nm, respectively. The epsilon value of the blue azopigment, obtained with the Reference Method for total serum bilirubin, was 76,490 L.mol-1.cm-1 at 598 nm. When the addition of alkaline tartrate was omitted, the molar absorptivity of the red azopigment was 56,600 L.mol-1.cm-1 at 530 nm.
Effect of calibration on dispersion of glycohemoglobin values determined by 111 laboratories using 21 methods
Authors: Weykamp C W , Penders T J , Muskiet F A , van der Slik W
Published: January 2020

One hundred eleven laboratories, using 21 different methods based on five different principles, determined glycohemoglobin (GHb) percentages in two identical series of six lyophilized hemolysates and three similarly processed calibrators, distributed 3 months apart. To assign GHb percentages to calibrators, we used HbA1c results from nine participants who used the Bio-Rad Diamat high-performance liquid chromatographic method. Three-point calibration with assigned values improved mean intralaboratory variation (CV) from 6.6% to 3.5%. For samples with low (5.5%) and high (14.1%) GHb percentages, respectively, calibration decreased interlaboratory variation per method (from 10% to 4% and from 6% to 3%), inter-method variation (from 18% to 4% and from 16% to 3%), and overall interlaboratory variation (from 25% to 7% and from 15% to 4%). Without calibration, 71% of the laboratories did not meet the clinically desirable intralaboratory CV of 3.5%; calibration reduced this proportion to 39%. We conclude that, irrespective of the analytical method used, calibration greatly reduces all sources of GHb variation.
Concanavalin A-bound selenoprotein in human serum analyzed by graphite furnace atomic absorption spectrometry
Authors: Daher R , Van Lente F
Published: January 2020

We developed an assay for the direct determination of selenium in serum with a Perkin-Elmer Model 4100ZL Zeeman atomic absorption spectrometer and Ag-Cu-Mg modifier. We used this assay to analyze concanavalin A-bound selenoprotein (CABSP) in human serum after concanavalin A (ConA) affinity chromatography. The CABSP was identified as a single-chain glycoprotein of 57.3 kDa. Carbohydrate units were N- and O-linked to the protein. The selenium moiety was selenocysteine. Total selenium, glutathione peroxidase (GPX; EC 1.11.1.9), ConA-bound selenium (CABS), and alpha 1-acid glycoprotein (AAG) were determined in normal subjects and patients with various pathological conditions. CABS accounted for 44.1% +/- 6.3% of total selenium in sera from normal subjects and 46.5% +/- 3.9% to 55.1% +/- 8.1% in sera from patients with a variety of diseases. Total selenium in serum was well correlated with serum CABS (r = 0.860), but not with serum GPX activity (r = 0.117), for all patients studied. Serum CABS increased in normal subjects after selenium supplementation. Serum CABSP did not behave as an acute-phase reactant, compared with AAG.
Semiautomated detection of human papillomavirus DNA of high and low oncogenic potential in cervical smears
Authors: Terry G , Ho L , Szarewski A , Cuzick J
Published: January 2020

Detection of DNA from human papillomaviruses (HPV) of high and intermediate oncogenic risk in cervical smears may predict the presence of cervical cancer or may indicate precancerous changes. Here we describe a semiautomated polymerase chain reaction system for the detection and classification of HPV DNA that is present in clinically significant amounts in routine cervical scrapes.
Felbamate measured in serum by two methods: HPLC and capillary electrophoresis
Authors: Shihabi Z K , Oles K S
Published: January 2020

We have developed two methods for determining serum concentrations of felbamate, a new anticonvulsant drug. The first method is based on protein precipitation with acetonitrile, followed by HPLC. The between-run CV for this method is 5.7% (mean 55 mg/L), and the linearity extends from 5 to 175 mg/L. Results by this method compared well with those by an HPLC method based on chloroform extraction (r = 0.98, n = 21). In the second method, based on micellar electrokinetic capillary chromatography, the drug is measured by capillary electrophoresis with direct injection of serum. This method can be completed in 5 min compared with 12 min for the HPLC method, and there is no need for sample extraction. The between-run CV is 5.2% (mean 58 mg/L) and the linearity range is 5-160 mg/L. Results of this direct method correlated well (r = 0.98, n = 37) with those by the HPLC assay. The mean trough serum concentration of felbamate in 123 patients taking this drug was 44.9 mg/L (range 12-129 mg/L).
Allowable imprecision for laboratory tests based on clinical and analytical test outcome criteria
Authors: Westgard J O , Seehafer J J , Barry P L
Published: January 2020

The allowable imprecision for laboratory tests has been estimated from criteria based on clinical and analytical test outcome. The analytical outcome criteria studied are the Clinical Laboratory Improvement Amendments (CLIA) criteria for proficiency testing. The clinical outcome criteria are estimates of medically significant changes in test results taken from a study in the literature. The estimates of allowable imprecision were obtained from quality-planning models that relate test outcome criteria to the allowable amount of imprecision and inaccuracy and to the quality control that is necessary to assure achievement of the desired outcome criteria in routine operation. These operating specifications for imprecision are consistently more demanding (require lower CVs) than the medically useful CVs originally recommended in the literature because the latter do not properly consider within-subject biological variation. In comparing estimates of allowable imprecision, the CLIA outcome criteria are more demanding than the clinical outcome criteria for aspartate aminotransferase (asymptomatic patients), cholesterol, creatinine (asymptomatic patients), glucose, thyroxine, total protein, urea nitrogen, hematocrit, and prothrombin time. The clinical outcome criteria are more demanding for bilirubin (acute illness), iron, potassium, urea nitrogen (acute illness), and leukocyte count. The estimates of allowable imprecision from analytical and clinical outcome criteria overlap for aspartate aminotransferase (acute illness), bilirubin (asymptomatic patients), calcium, creatinine (acute illness), sodium, triglyceride, and hemoglobin.
Bilirubin production in healthy term infants as measured by carbon monoxide in breath
Authors: Stevenson D K , Vreman H J , Oh W , Fanaroff A A , Wright L L , Lemons J A , Verter J , Shankaran S , Tyson J E , Korones S B
Published: January 2020

To describe total bilirubin production in healthy term infants, we measured the end-tidal breath CO, corrected for ambient CO (ETCOc), with an automated sampler and electrochemical (EC) CO instrument. For infants of mothers with a negative Coombs' test, the ETCOc was 1.3 +/- 0.7 microL/L (n = 397) and the serum bilirubin on day 3 postpartum was 73 +/- 35 mg/L (n = 381). In contrast, the ETCOc for infants with ABO or Rh incompatibility, a positive direct Coombs' test, and bilirubin > 130 mg/L (n = 9) was significantly higher, 1.8 +/- 0.8 microL/L, than for those who had a positive Coombs' test result but whose bilirubin was < or = 130 mg/L (n = 12), 1.0 +/- 0.5 microL/L (P < 0.05). At 2 to 8 h postpartum seven term babies from mothers with insulin-dependent diabetes had ETCOc of 1.8 +/- 0.7 microL/L, significantly higher than that in the other term infants [1.3 +/- 0.7 microL/L (n = 390), P < 0.04]. Their bilirubin concentration at 72 +/- 12 h was also higher: 121 +/- 45 mg/L (n = 7) vs 73 +/- 34 mg/L (n = 374; P = 0.03). We conclude that ETCOc measurements may be helpful in understanding the mechanisms of jaundice in healthy term infants in a variety of conditions.
Systematic differences between commercial immunoassays for free thyroxine and free triiodothyronine in an external quality assessment program
Authors: Zucchelli G C , Pilo A , Chiesa M R , Masini S
Published: January 2020

Data collected in a national external quality assessment program for free thyroxine (fT4) and free triiodothyronine (fT3) were analyzed to evaluate the performance of 10 method/kits with 26 control samples distributed to approximately 170 laboratories. The control materials were normal serum pools, pooled sera supplemented with thyroid hormones, a pregnancy serum pool, serum pooled from patients with familial dysalbuminemic hyperthyroxinemia (FDH), and a normal serum pool progressively diluted. The between-laboratory variability (CV) was approximately constant in normal and supplemented pools for fT4 (15.3%) and fT3 (24.0%) but markedly increased in diluted, pregnancy, and FDH pools (21.9-35.2% for fT4 and 28.6-66.5% for fT3) because of increases in systematic between-kit differences in control samples with altered binding-protein capacity. Moreover, free hormone concentrations measured in progressively diluted sera averaged lower than in undiluted samples. This decrease of concentration was less for back-titration or labeled-antibody techniques and greater for labeled-analog methods; only the method involving adsorption to cross-linked dextran (Sephadex) was unaffected by dilution. Evaluation of the reproducibility of the method/kits showed between-assay, between-laboratory precision ranging from 7.8% to 17.0% for fT4 and from 9.8% to 20.3% for fT3.
Fully enzymatic method for determining 1,5-anhydro-D-glucitol in serum
Authors: Fukumura Y , Tajima S , Oshitani S , Ushijima Y , Kobayashi I , Hara F , Yamamoto S , Yabuuchi M
Published: January 2020

We have developed a fully enzymatic method to measure 1,5 anhydro-D-glucitol (1,5-AG) in serum through use of pyranose oxidase (PROD: EC 1.1.3.10), glucokinase (EC 2.7.1.2), and an ATP-regenerating system. In a previous report (Clin Chem 1989;35:2039-43) the glucose interfering with the measurement of 1,5-AG was removed with a minicolumn. In the method used here, glucokinase and an ATP-regenerating system efficiently convert glucose to the unreactive compound, glucose 6-phosphate, making the method selective for 1,5-AG. The hydrogen peroxide produced in the oxidation of 1,5-AG by PROD is detected with a standard enzymatic color-developing system. The within-run and day-to-day precision (CV) of this method was 0.52-1.29% and 1.17-4.48%, respectively. The correlation (r) between the results obtained with our proposed method (y) and those obtained with the mini-column method (x) was 0.998 (y = 1.007x + 0.493 mg/L; n = 100; Sy/x = 0.641 mg/L). This newly developed method allows quicker and easier measurement of serum 1,5-AG than previously described methods.
Variance function as basis for assessment of test performance: methodological studies with two assays of prostate-specific antigen
Authors: Hänseler E , Keller B , Keller H
Published: January 2020

We evaluated the usefulness of a recently described procedure to assess the analytical performance of an assay. To demonstrate the advantages of this approach, we compared the performance of two analytical systems for determining prostate-specific antigen (PSA). Triplicate measurements of PSA with the IMx (Abbott) and the ACS 180 (Ciba Corning) were used to calculate the variance function. This function was the basis for the derivation of the critical limit (LC), the limit of detection (LD), the power of definition (PD), and the lower limit of the quantification interval. The standard deviation of the blank was extrapolated by means of the variance function. LC was calculated as the concentration at which the normal distribution of the blank intersects an adjacent normal distribution (with a defined overlap, e.g., 5%). The mean of the adjacent normal distribution represents the LD. The PD is a new mathematical approach to describe the analytical sensitivity of an assay in different ranges of the quantification interval. The procedure is statistically well defined and allows one to obtain the data on the test performance directly from patients' samples, without artificial zero controls. Therefore, use of the variance function could be a general model for the assessment of the analytical performance of an assay.